# Sticky  Acoustical Treatments Master Thread



## JBS

OK, this seems straightforward from searching AVS and studying theater wall treatment...


FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.

CEILING: No acoustical treatment - none, nada.

FLOOR: Thick, plush carpet is fine.


But here's where it gets confusing, and I need help...


SIDEWALLS

A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.

--or--

B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.


These 2 theories seem to contradict each other. So which is it?



BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:


Owens Corning Select Sound Black Acoustic Board

Owens Corning Fiberglas 703 Series duct insulation.

Johns Manville Insul-Shield

Johns Manville Linacoustic Permacoate rolls.

Certainteed Certpro Acoustaboard Black

Knauf Duct board EI-475

Knauf Duct liner EM


...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.


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## Dennis Erskine

First, (B) is wrong. Virtually every surface is a first reflective surface (speaking of walls). "B" is actually treating those early reflections which meet the listener's ears within a time frame described by Helmut Haas (further researched by Toole and Olive). Depending upon the delay due to the longer path to the ear will result in the sound being perceived as a distortion, or echo. As well, sounds reflecting off a surface suffer timbre shift. Next, you don't care a twit about "early reflections" that don't intersect the listening position.


The 'early reflections' technique is more typically found in two channel playback environments where higher reverberation times in the room are required to make up for the absence of surround channels (or intelligent surround processing techniques).


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## Ethan Winer

JB,


I agree with Dennis that B is wrong. I'll go even further and say you should never cover any large surface area with material that absorbs the mids and highs. It makes the room too dead sounding, and does nothing to solve the inevitable low frequency problems. Much better is a mix of bass trapping and mid/high absorption, with no one area all live or all dead.


--Ethan


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## Dennis Erskine

Now "A".


Requirements for multi-channel (more than 2) are different than that required for 2 channel.


In multi-channel, the entire wall behind the front speakers is treated. You want none of the back reflections to overlay the surround field or the bring the reverberent field forward (your reverberent field and surround field is created by the multi-channel processor or mix, not so much the room as is mandatory for 2-channel). Depending on speaker placement, this treatment is brought forward along the side walls. Wall treatments are floor to slightly above ear level (where exactly is also a function of front speaker heights). While one could argue the sound at their feet is of no concern, often that square footage of treatment is required to bring the room's RT60 down to the lower levels required for multi-channel playback.


If you have soffits, the bottom of the soffits is also treated...several reasons, right tricorners among them.


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## JBS

Sorry, two additional questions...


1) Is 1" Insul-Shield (or equivalent) adequate for the front wall, or should it be increased to 2" if possible?


2) If side wall treatment is only be up to early level, then what should be done to fill out the 1" fabric above ear level: polyester batting or 1" styrofoam insulation to maintain the full reflective surface? I've heard both argued, but don't know if there's much difference.


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## Dennis Erskine

I would not use the 2" material...it will very likely be too absorptive.


The fill out is polyester batting. Don't use styrofoam.


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## gregr1

The diferent reqiurements for 2 channel and multi channel is interesting. So obviously there is no way to make a room work as well for both uses as it would for each task specifically. However what should be the general guidelines for a room that would be used for both 2 and multi channel - so as to do the least damage to either format?


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## Dennis Erskine

Compromise between the two playback scenarios is not a good option. Effectively you're saying you're (a) willing to spend a bunch of money and (b) happy to make the room sound poorly in either case.


If you have a good surround processor and a well set up multi-channel room, play your 2 channel recordings in multi-channel mode...a better result. I can assure you a good surround processor will do a whole bunch better job of creating the spaciousness than your room can accomplish.


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## obie_fl




> Quote:
> _Originally posted by Dennis Erskine_
> *If you have soffits, the bottom of the soffits is also treated...several reasons, right tricorners among them.*



Very informative thread as usual from Dennis. So are the undersides of the Soffits treated for absorption (Insulshield) or diffusion (batting)?


Tom


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## PamW

Since this thread is going, I also have a question -


You have mentioned the front wall and the side walls for acoustical treatment, but what about the rear wall? Is it different with a 5.1 setup vs a 6.1 or 7.1?


Pam


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## chs4




> Quote:
> _Originally posted by obie_fl_
> *Very informative thread as usual from Dennis. So are the undersides of the Soffits treated for absorption (Insulshield) or diffusion (batting)?
> 
> 
> Tom*



Tom,


I don't want to speak for Dennis but the underside of your soffits should be treated for absorption. (Insul-Shield)


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## JBS

Treating the underside of cove lighting soffits will have to be explained to me... especially if they are at 8' height (with the majority of ceiling at 9'). If one is using dipole surround speakers, it would seem that treating the soffits could make the surrounds less diffusive and more identifiable to the ear.


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## DennisBP

I am also interested in the question Pam asked about the rear wall in a 7.1 setup. I will likely use duct wrap on the front wall and below ear level on the side walls. The consensus seems to be nothing on the rear walls or ceiling - correct?


Another question - A non-perf screen reflects quite a bit of sound, but does it pass enough to acoustically treat the wall behind it?


Dennis


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## RRBOOGIE

I am curious about the room treatment used specifically on the front wall behind Omnipolar speakers(Mirage OM 10). Does too much apsorption defeat the Omnipolar characteristics of a speaker?


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## Dennis Erskine




> Quote:
> Does too much apsorption defeat the Omnipolar characteristics of a speaker?



Yes. And, that's what you want.


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## proufo




> Quote:
> _Originally posted by JBS_
> *These 2 theories seem to contradict each other. So which is it?
> *



Hello JBS.


You may want to check my free Mediaroom spreadsheet. Send me email at [email protected] .


As Dennis points out, music listening has different requirements than HT, especially with stereo/mono sources.


At this point I believe the best arrangement for a multi-purpose room is to make it deadish for HT and perhaps m-ch mixes, and use the same setup for recreating or extracting ambiance for 2-ch music sources.


Best regards.


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## Ted White

I would offer that treating the undersides of large soffits could overdamp a room. Ideally you'd leave it alone until tested.


Ted


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## PamW

But what about that rear wall guys???


Do you treat it or not? Do you treat it differently if it were 5.1, 6.1, or 7.1 surround?


(Can you tell I'm getting close to that part of my construction?)


Please help this pitiful female...

Pam


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## CptnRandy

Mine is treated the same as the sides.


Of course, I was just following the plans, which was a great relief to me.


Randy


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## PamW

Thank you, Randy! I feel better now....


Crisis averted for now. Hysteria is gone.


Pam


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## Ted White

Yep, That's classic Dennis construction right there!


There are two types of walls: Front walls and all others.


Again, this is for HT rooms, multi-channel playback not dedicated two channel.


Ted


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## bpape

For what it is worth, my opinion is that the rear wall is a bit different than the sides.


In smaller rooms, you can use the rear wall as a point to place diffusion. This helps with standing waves a little, helps RT60 a little, and does not overly damp the room making it sound too dead. You can mix a bit of absorbtion ( I do opposite the screen since you can't treat that on the front wall) but not so much that you kill the surround reflections you want/need.


Overall, I prefer strips of absorbtion, say 9-12" wide by 1- 1 1/2 " thick by 5' tall. Put these at first reflection points for the main fronts, and the rest every 3-5' along the side walls with the center of the panel (vertically) being about your ear level. You end up with about the same sq. ft. coverage as the whole bottom up to ear level but it is distributed throughout the room more effectively IMO. Yes, the front wall should be totally dead.


Keep in mind that mine is for music and for theater. Personally, I think HT can sound very good in a 'properly designed' 2 channel room with just a few mods that don't hurt 2 channel that much. I have not heard the same results from 2 channel in a 'properly designed' multichannel room. Usually sounds very dead and the soundstage is severely closed in. If I am going to err to one side or the other, I will err toward the 2 channel design.


As for having to play all my music through multichannel because I did the room for HT, I'll pass. I spent a ton of cash getting components that recreate music well without a lot of processing. I'm not going to pass them through multiple signal modifications.


Don't misunderstand me. Dennis is describing good practice, theory, and lots of experience with DEDICATED HT environments. If that is your goal exclusive of music listening, go for it. If you are like many of us who also use this space for a high quality music listening space, play with it a little and see what you like. After all, that is what it's all about - what YOU like. It's your room.


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## Dennis Erskine

A couple of minor points: diffusors do not affect RT60 in the manner described nor will they have any impact on standing waves.


While vertical strips can create a moderate amount of diffusion, you cannot cover all the early reflection points to all seats effectively. In the 'ear level' scenario, you do have 'stuff' bouncing around above your head; but, if you watch your angle of incidence against where your speakers are placed (height), you've covered all the bases within the curve. This is also a much more effective method with rows of seating since you'll have more people close to the side/back walls than in a two channel, single seat of excellence environment.


In multi-channel...no bad seats not one good seat.


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## bpape

Not suggesting that you hit all the first reflection points, just the side wall points from the main L and R.


Diffusion (diffraction) does indeed assist with RT60 and elimination of standing waves. Look at any anechoic chamber. There is NO abosrbtion. ALL diffusion. No standing waves in there. What is the RT60 in an anechoic chamber (understand they are all different, rhetorical question.)


If the the absorbtion is placed appropriately (not directly across from other absorbtion) and diffusion allows the wave to be changed from a first axial to a tangential reflection onto various absorbtive features, you are in fact lenghtening the time till it hits another reflective or absorbtive surface, thereby extending the time and distribuiting the wave across more absorbtive surfaces (assuming good polar plots on the diffusors).


Like I said Dennis, don't get me wrong. For pure HT, your way is probably best. I want it all. I want 1 good seat AND no bad ones. Your 'non-bad' ones may be a tiny bit better but my 1 good one is killer when its just me sitting down listening to music.


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## Dennis Erskine

An anechoic chamber is all absorption (ever done research in one?). Like this one for example:
http://www.bell-labs.com/org/1133/Re...icChamber.html 


Sound decays (STP in air) at the rate of 1/r squared. The rate of decay is not affected by reflection (a form of diffusion). It is affected by distance and absorption.


The purpose of diffusion is to randomize reflections which will result in axial, tangential and oblique reflections.


RT60 is the time it takes for the sum of all reflections to decline 60dB once the sound source ceases. The calculation is RT60=0.049(V/Sa). [where V is volume, S is surface area, and a the absorption coefficient). In an anechoic chamber RT60 is statistically 0 since there is no reflection. Sound reflecting from a wall surface or a diffusor will decay at the same rate.


The location of absorptive materials (except in certain cases in small venues) has no impact on the RT60; however, the placement and type of diffusors will have impact on the proper creation of the reverberent field.


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## bpape




> Quote:
> _Originally posted by Dennis Erskine_
> *An anechoic chamber is all absorption (ever done research in one?). Like this one for example:
> http://www.bell-labs.com/org/1133/Re...icChamber.html
> 
> 
> Sound decays (STP in air) at the rate of 1/r squared. The rate of decay is not affected by reflection (a form of diffusion). It is affected by distance and absorption.
> 
> 
> The purpose of diffusion is to randomize reflections which will result in axial, tangential and oblique reflections.
> 
> *



Learn something every day. I always thought the wedges were all edge hardened in those chambers so they acted more like diffusors. Guess I will have to stand corrected on that one.


My comments were only made to present the poster with options, not to rebutt any other previous statements. They were also stated understanding that I was trying to provide a compromise solution not knowing what the poster's use was for the room.


Even though what I was describing may not be significant in pure RT60 terms, I still don't get how forcing a portion of a wave to travel through more air and through more absorbers before bouncing back at the user from the front can't help. Remember, I was only discussing diffusion on the rear wall, not the sides. If it takes the same amount of time to decay but each wave bounces back at my position fewer times and from more different directions within that space of time, how can that not help the situation?


Besides the above stated, it appears to my ears, to provide 2 other benefits. In surround mode, the rear portion of the surround field gets scattered more evenly thereby increasing the sense of envelopment. In 2 channel, forcing the wave to travel a longer distance before coming back off the front wall makes the space appear acoustically larger than it actually is. Not all rooms require this but you don't run the risk of sucking the life out of the sound if you put some up. Like you said, reflection does not effect the rate of absorbtion.


Also, if I the room is a bit live, the only time I would worry about it is when it is just me in there. At that point, I am probably listening to music so it works better that way. When we are watching movies, there are 4-12 wonderful abosobers that get added to the room called people spread throughout the middle of the space.


I have heard rooms done both ways. Both can sound very good when doing multichannel duty. Like I said before, I have just never been able to find that one sweet spot for stereo when you totally optimize for surround, even when sitting in the nearfield of the front speakers. Just my opinion but I'll sacrifice a tad on the ultimate in multichannel quality to get that sweet spot back.


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## Dennis Erskine

Diffusion is helpful. Placement is important. The object is the creation or (or preventing the destruction of) the reverberent field.


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## Mancubus

I have a quick question for you guys regarding sound treatment....


I've read and understand that the area below ear level should covered with Insulsheild (or an equivalent) and above should be covered with batting. My question is, for the second and possibly third rows, should you raise the height of the insulsheid to accomodate what would be below ear level for those on risers? I.E. from front wall to first row Insulsheild is installed to the height of 4ft. Once you get to the row with a 12" riser, do you then increase the height of the insulsheild to 5ft or do you go with 5ft from front to back? What is the 'general' rule to follow?


TIA.


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## bpape

Some do, some don't. The idea is to cover a certain percentage of the wall with more absorbtion. If you go higher on shorter walls, you are actually increasing the percentage of the wall that is covered.


I don't know any general rule of thumb about this. Dennis could probably provide a more experienced answer for this type of implementation.


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## dmcvie

So to follow up on dpape's last question...


What goes above the lower panels? I was thinking of just wraping "board" with polyfill and then covering in GOM. I'm hoping to have all the panels just look the same size and appearace.


My concern is the sound absorption (or lack of) if I dont use the right materials for the foundation of the upper panels.


Anyone have a sugesstion?


Thanks


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## PamW

Polyester quilt batting is the recommended upper covering right on the drywall - the hard part is finding the 1" thick stuff. I have discovered it at Hancock Fabrics. Also check quilt stores.


pam


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## dmcvie

Thanks Pam,


It seems (from post & pictures) that people are just putting the batting directly on the wall and covering it with fabric? This seems pretty difficult to me?


I was thinking of using 2'x4' sheets of "board" (1/4" plywood?), covering them with the batting and wrapping them in GOM fabric. The trick (and I still don't know how I'll do this) is to then mount these on the wall. My thinking is that this will give me a nice "matched" look of panels (some sized differently for looks), and I should be able to get the upper wall panels and lower wall panels to match - much like the custom theater rooms I've seen.


This method also allow me to build the panels on the floor and glue/staple the fabric perfectly before I hang them on the walls. I think it should give a better result than trying to cover the batting directly on the walls?


Am I missing something here (other than how to attach the panels to the wall), or shouldn't this give a very finished look??


Dave


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## akshark




> Quote:
> _Originally posted by dmcvie_
> *Thanks Pam,
> 
> 
> It seems (from post & pictures) that people are just putting the batting directly on the wall and covering it with fabric? This seems pretty difficult to me?
> 
> 
> I was thinking of using 2'x4' sheets of "board" (1/4" plywood?), covering them with the batting and wrapping them in GOM fabric. The trick (and I still don't know how I'll do this) is to then mount these on the wall. Dave*



Dave,


This is a great idea. I seen a similar project on HGTV the other day. They were using 2X2 panels and alternating colors. They attached them with 2-3 inch wide Velcro. Makes it easy to change patterns?


This was not a theater project but would work just the same.


Just a thought.


Scott


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## dmcvie

Thanks Scott,


Good idea on the Velcro. I'm wondering if there any any "accoustical" concerns for this type of construction or method of hanging them? (Dennis







)??


Sure it has to sound good, but it has to look good too.


Dave


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## adamf

Dave,


The reason for the polyfill on the upper wall is due to the fact most build out the wall with the firing strips and insulshield on the bottom. Covering the upper, drywalled half with fabric and no polyfill gives a sag in the middle of the stretched fabric.


The polyfill only serves as fill, it theoretically has little acoustical impact (some diffraction, eh?) but still lets the sound waves hit the dry wall and be reflective and alive.


One could due 'hard" reflective panels above and soft, absorbent below ear level (keeps dialog and such clean from first reflections).


There are some heavy duty picture mounting "spikes" which could be used for mounting purposes. We used them to secure our pictures so they wouldn't rattle.


Good Luck,

Adam


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## dmcvie

Thanks Adam, that helps my understanding. I took a look at your pictures, Great Job! I hope to accomplish a similar look.


Is the entire rear of you screen wall covered in Insulshield? Can you tell me where you got it? I was going to use sound board, but I think Insulshield does a better job at lower freqs.


Thanks again for you input.


Dave


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## adamf

Thanks.


Yes, we covered the entire area behind the screenwall (the screen is actually mounted on a false wall about 18" in front of the real wall. We also covered the side walls next to the speakers, top to bottom (the speakers are another couple inches in from of the screen wall).


Think of a theater stage and my speakers are in the "wings" in front of where the Theater curtains would be (my hope eventually is to mount some drapes).


I actually used the Owens Corning Sound Select due to some issues about getting the Insulshield locally. The specs are quite similar. Let me know if you need it, I have the PDF or web address around somewhere if you can't find it on their website.


Adam


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## Eric Desart

Hello Dennis:











> Quote:
> _Originally posted by Dennis Erskine_
> *
> 
> The location of absorptive materials (except in certain cases in small venues) has no impact on the RT60*













You REALLY shouldn't say that:


Look at picture (copyright) below:

Measured by me in official University Lab.

Method as per ISO 354 - standard reverberation room method (except for position) on the same day with exactly the same rigid rockwool slabs framed with very light metal frame to screen off edges.

You could almost ask: which one do you like best.

So the only varying factor is the position in the room and how it's used.


Also look here:
http://www.ib-neubauer.com/Literatur...001_Rome_1.pdf 

Predicting Reverberation Time: Comparison between Analytic Formulae and Computer simulation with CATT room acoustic program.


Sabine and Norris Eyring assume statistical distributed absorption, boundary conditions and reflections.

Millington allows assymetric absorption.


Fitzroy and the improved Higini Aray Puchades approach try to solve the shortcomings of the above approaches in function of assymetric distribution of absorption.


An official Reverberation Room is tuned with added diffusers to the MAIN material sample spot.

There is the edge effect and so much more.


Best regards

Eric


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## Eric Desart




> Quote:
> _Originally posted by Eric Desart_
> *Look at picture (copyright) below:
> *



Sorry I've no idea how to enter the picture.

I resized it it's not too large (nor size nor bandwidth) but it doesn't appear.


If somebody can give a hint (no time to try for hours just for a picture).


Regards

Eric


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## Dennis Erskine

Well, Eric, you are exactly correct. As it is true that making glittering generalities about any complex process can get one into hot water when shifting through the details later.


However, as I've noted in other postings, as room size decreases, traditional methods of predicting RT60 cannot be considered terribly accurate without use of ray tracing techniques. (In actuality, as architectural and other elements -- people for example -- become larger with respect to total room size. As you are aware, the same would hold true for any attempts to accurately model or predict modal resonances without both ray tracing and finite element analysis. As well, with variances in physical "as built and installed" properties, we find stochasic analysis in monte carlo simulation helpful. These models, however, have the down side of running for multiple hours. In the end, models are useful to prevent expensive errors and the effort is to be statistically accurate such that once we can measure the actual space we're faced with 'tuning' rather than rebuilding.


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## Eric Desart




> Quote:
> *Originally posted by Eric Desart
> 
> Look at picture (copyright) below:
> *



Tryed it once more. Hope it appears.

It's hard to believe this are results from the same material measured in environment designed to exclude as much as possible site phenomena.


Please respect the Copyright of this picture resulting (as part of) extensive study.

It mainly shows how difficult it is to transfer Sabine values to real life circumstances.

It also shows that one should be really careful when interpreting Sabines.


Sabines are only partly a material property.


Best Regards

Eric


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## Eric Desart

Dennis,


I agree with you.


This subject goes to far in detail.

Real life alpha is indeed one of the most difficult things to define exactly.

A lot of it is empirical.

In geometric acoustics (ray or cone tracing) it's a bit easier (averiging affect), with BEM and FEM, however accurate the models, the problem indeed remains the input (boundary impedance).

A lot of it are statistical empirical approaches.


I'm just responding to general statements, which can cause confusion.


Best regards

Eric


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## Dennis Erskine

Well, yes, we're always faced with the garbage in/out problem...the accuracy of models are highly dependent upon the accuracy of the data (and our assumptions). What we've found with out monte carlo in finite element analysis (data input by density function, point estimate or normal distribution) is we can begin to refine the estimates based upon a result history. I also have found in many cases the assumption is the data is right so when the measurements are done and do not follow prediction prediction, there's a tendency to be looking in the right place...sort of follows along with the issue that many are not properly interpreting the measured results. (Now, I am rambling. Sorry all.)


My research (grant approval not withstanding) now is in the area of various construction techniques (as applied to acoustic solutions) and am looking to generate some research into the issues of Timbre matching surround speakers.


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## gjlowe

I like the idea of using panels on the walls instead of a complete batting covering for the top half of the wall. In fact, if you put a ledge molding instead of chair rail around the walls, do you even need treatment on the upper half? If so, could you use the panels as dmcvie suggests? How far apart would you have to place them on the wall?


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## bugman72

In reference to making panels for the upper half of the side walls, here's a link that I've kept handy for quite some time. It's from the AVScience website and was written by Andrew Tierney. While it might not be the end-all beat-all way to do acoustic panels, it gives someone a good guideline to follow if they want to go this route.


As for which one is easier to do, I have no idea. I'm not even to that stage of construction (going to be putting up drywall in the next week or so). Someone else might be able to chime in and enlighten us on the matter.


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## Ethan Winer

Greg,


> it might not be the end-all beat-all way to do acoustic panels


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## bugman72

Like I said, it's not the end-all beat-all way...but it gives someone who has never seen an acoustic panel or has no knowledge on how to make one a guideline. I can neither confirm nor deny their effectiveness as I have not built any. I simply put the link out there, if for no other reason, to help someone figure out how to create their own acoustic panels.


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## gjlowe

Thanks for the link. Bottom line is if possible, I would prefer to NOT cover the entire upper wall with the batting, but if that is the easiest and cheapest way to do it, I will go that route. I just can't see it being the cheapest because of the wall fabric.


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## smithb

I am very interested in an answer to "gjlowe" question:


"if you put a ledge molding instead of chair rail around the walls, do you even need treatment on the upper half?"


My plan is to treat the whole lower half (ear level and below) of the room as suggested (except full treatment on front wall). However, I have read mix messges on the value of using cloth covered batting on the top. Some say it is for acoustical purposes and some say that it just pushes the upper wall out to meet the treatments of the bottom half. I personally would like to just paint the top half and build a ledge in the chair rail to save money if batting doesn't add any additional value. So which is it?


What is the rule about hanging pictures on the upper walls?


Some treat the lower half of columns and others do not. Is there a reason to go one way or the other?


I see many putting heavy curtains along the front wall which looks very nice. What impacts does this cause on the front wall treatment? No impact or cancel it out?


Finally, do people treat the wall area behind the screen?


Thanks for any feedback.


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## Ethan Winer

Greg,


> Like I said, it's not the end-all beat-all


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## smithb

I really could you use some advice based on the following questions:


-----------------------------------------------------------------------------------------

I am very interested in an answer to "gjlowe" question:


"if you put a ledge molding instead of chair rail around the walls, do you even need treatment on the upper half?"


My plan is to treat the whole lower half (ear level and below) of the room as suggested (except full treatment on front wall). However, I have read mix messges on the value of using cloth covered batting on the top. Some say it is for acoustical purposes and some say that it just pushes the upper wall out to meet the treatments of the bottom half. I personally would like to just paint the top half and build a ledge in the chair rail to save money if batting doesn't add any additional value. So which is it?


What is the rule about hanging pictures on the upper walls?


Some treat the lower half of columns and others do not. Is there a reason to go one way or the other?


I see many putting heavy curtains along the front wall which looks very nice. What impacts does this cause on the front wall treatment? No impact or cancel it out?


Finally, do people treat the wall area behind the screen?


Thanks for any feedback.

-----------------------------------------------------------------------------------------


Any response from the experts would certainly be appreciated: Dennis or Eric?


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## proudx

now obviously we use the insulshield to get the RT60 down to a good level.


Is the general rule of using insulshiled up to ear level and below all the way around still followed when using a drop ceiling with acoustical tile?


I would think the acoustical tile would lower the RT60 somewhat and less insulshield would be needed.


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## filmnut




> Quote:
> _Originally posted by gjlowe_
> *I like the idea of using panels on the walls instead of a complete batting covering for the top half of the wall. In fact, if you put a ledge molding instead of chair rail around the walls, do you even need treatment on the upper half?*



No, you don't. The batting, as I understand it, is not there for acoustical purposes, but simply to provide some support under the fabric that you would install so that the upper wall surface is flush with the lower wall surface. If you don't care about that, as I don't, then simply install any type of molding on the top of the ledge to hide the staples.


In my case, I simply stapled fabric directly to the drywall surface on the upper walls. If you do this, I highly recommend painting the drywall surface flat black first. Otherwise, the white drywall surface can sometimes reflect light back through the fabric.


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## Jeff Hovis

Great thread! I have a complex situation. I'll provide some background, then a question:


We have (for now) a multi-use room in our basement. It is 14x30 and I have a theater in a section that is 14x16. The rest is a playroom for our daughters.


I have treated the front wall. The screen, front and center speakers are 30" from the wall. There is a 36" TV and 72" tall cylinder sub behind the screen and curtains on the sides.


Behind the seating area which is 12' from the screen are two MDF columns that are 4' apart. These columns are 16' from the front wall. There are MDF shelves running between the columns that actually form 2x2 cubes. The idea was to form a room divider and a diffusive surface with these (imagine a tic-tac-toe grid between the columns). The side walls are currently treated with acoustic panels at reflective points back to the rear columns (16').


I plan to rework the room and treat the sidewalls with GOM.


I know that's a lot of description and visualization.


My question:

Do I need to treat the entire 14x30 room or can I stop at the 16' mark? Remember, the rear columns/shelves form a room divider which is probably more visual than anything. But, the wall treatment could stop there and it would look fine. I'm just not sure about the sound.


Maybe I should just leave it as is until I can repossess the entire room from our daughters.


Jeff


----------



## mark haflich

OK. Into the fray regarding wall, ceiling, and floor treatments to tune the room. Construction of the walls and ceilings (assume a concrete floor) is a whole different issue.


The screen wall wall should be soft absorptive. Ditto for the first couple of feet from that wall along the sides. The side wires generally should hard absorptive, say absorptive below 1000 cycles, reflective above. However spot soft absorptive is absolutely required. The placement is determined by the first reflective point for each of the three front speakers for each seat in each row of chairs. The idea is that each seat wants to hear only direct sound from each of the front three speakers. NO refctive sound please. Go to a commercial theater. You will soft absoeption just above your head on each side. That is there to ensure that the row behind you just like the row in front of you hears onle direct sound. LCR speakers in a commercial theater and hopefully yours as well have wide horizontal dispersion and narrow vertical dispersion. I assume risers for the second and more rows in your HT. Dependent on room dimensions and seat locations, you will need some spot soft absorption for the first row, and behind it but higher some for the second row and so on. Assuming close rear wall location to the last row, the rear couple of feet of the side walls and the rear wall should be diffusion on the top half and hard absorption below that.


The ceiling is another issue and is dependent on ceiling hight (I assume about 8 ft) and whether your center speaker is above, behind, or below the screen. High mounted left and rights enter also. Basically, with an above screen center (i.e., with the center mounted very close to the ceiling), you will need some soft absorption right in front of the center (a 2x4 ft) panel. With high mounted left and rights but with some distance to the ceiling, you will need some soft spot absorption (say four 2x2 ft panels) probably 2 spots just in front of the center two chairs and above the chairs on either end assuming a four chair row of HT type recliners.


Side and rear surrounds are generally mounted near the ceiling and these locations cry out for ceiling diffusion in front of each speaker. The rest of the ceiling depends on the type of ceiling. You do not want a painted sheet rock surface. At a minimum use some acoustical bubble filler in the paint or a textured sand. Hard absorption is good but expensive. Acoustical tile say with an NRC of .75 but you should weight down the tile by gluing sheet rock to the back and then you should put some fiberglass wall or ceiling insulation over that. Treatment of the space between the joists is an issue of room isolation rather than room tuning though it will affect the tune.


Your floor should be carpeted but do not use a foam or rubber pad. Horse hair jute is the best but is generally no longer available because of youths smoking it for the hemp. 1/2 inch felt padding to me is the next best thing BUT put the bonding surface side down (normal carpet insulation is to put it up so that the tape the installers use to hold pad sections together will not tear the pad).


----------



## gjlowe

So how do you figure the first reflective points for the LCR speakers?


----------



## mark haflich

You can pay a qualified acoustician to calculate the room modes, reflection points etc, and recommended surface treatments and the locations for those treatments. We charge our clients $1700 for this service and do the interfacing with the acoustician for the client. There are a variety of of the shelf programs which can also be used.


A simple way to locate first reflective location points if the room is built is to replace each front speaker with an incandescent light bulb. Use the woofer for the center point assuming a 2 way speaker. Next sit in each seat and have an assistant move along the walls with a small mirror. You will see a reflective point for each of the 3 front speakers along each of the 2 side walls for each chair. These points are the first reflective points. Ditto for ceiling reflections.


----------



## Dennis Erskine

The mirror method is "close enough for government work". Some thoughts:

1. be sure the mirror is flat against the wall/floor/ceiling;

2. consider all the seats (no bad seats);

3. check height as well as distance down the wall;

4. the tweeter is more critical than the woofer, none-the-less, your speaker or light bulb should be at the exact position of the speaker once installed (height, distance from wall etc.);

5. recognize you are *not* interested in just the first reflections...it's early reflections which would include reflections from the wall behind the speaker (unless you're treating that surface).

6. recognize that not all early reflections are bad...you're looking at the initial time delay gap along with the "Haas" effect, so "time" is more important than "first".


----------



## Ethan Winer

Dennis,


> recognize you are *not* interested in just the first reflections...it's early reflections which would include reflections from the wall behind the speaker (unless you're treating that surface).


----------



## MBK

Mark,


So you can't get the floor treatment because bozos are smoking it to get high?


That is hilarious!


----------



## Dennis Erskine




> Quote:
> There's no question that loudspeakers radiate low frequencies in all directions



Sound from the speaker radiates as a sphere. Thus all frequencies radiate in all directions. The speaker cabinet causes defraction but does not "cast a shadow". (One of the reasons the formula for determining acoustic energy decay (SPL) is 1/r^2.)


[If sound at all frequencies did not radiate spherically, you couldn't hear a speaker standing behind it. Although, I do claim I cannot hear what my son is saying when he's looking the other way.







]


----------



## mark haflich

I agree with Dennis.


Normally HTs are small, ranging from say 300 to 700 sq ft. The smaller the room, the more need for treatment behind the seats (rear wall and side walls). As to reflection points between the speakers and the seat, many will fall very close together so it's not like you have to treat a lot of spots. For a two row theater with the second row on risers, say 20 ft wide and 25 ft in depth, the side-wall soft treatment need not exceed about 24 sq ft per side.


The wall behind the front speakers needs to be dead. You want imaging. So by deadening the front wall you increase the point source characteristics of the front array. The problem here is that the screen often occupies a significant portion of the front wall and that sucker is reflective.


And yes, horse hair jute, in my many years of 2 channel experience, the best carpet pad for making a room sound good, is no longer commercially available. Too many "utes" were smoking it with bad side effects.


----------



## proudx

So treatment is a room 13ft by 20ft would need to be more aggressive on the side and rear walls than in a room 20X25ft.


----------



## mark haflich

I would say as a generalization, the closer you sit to the rear wall, the more it needs to be treated (with diffusion). Obvioiusly, if the rear is an an infinite distance behind you, there is no need to treat it. Likewise for the side walls. On the other hand, the bigger your room, the further away you will likely sit from the screen, say 15 or 16ft away at the closest instead of say 12 1/2 ft. The further away the more near reflections rather than just a first order you will need to treat, so there really is no clear generalization.


As Dennis says below (the power of an edit







), you really can't get a small room to sound (e.g., decay) like a large room. However, diffusion will help.


----------



## Dennis Erskine

As Mark pointed out, this really not a good thing for generalizations. Having said that, as a room gets smaller the time delay between the initial sound and the reflected sound decreases and the relative dB SPL increases. This would suggest different treatments. Part of the difficulty in smaller rooms, is developing the capability to create the reverberent field. As the delay becomes shorter and the difference in dB SPL between direct and reflected sound decreases, you can easily have problems.


----------



## Mancubus

My room is very small compared to most here. My finished dimension will be approx. 9'3"W x 21'L with 18' in the length visible since I will have a false screen wall with an acoustically transparent screen.


I am going to cover the front wall as suggested with sound absorbing material, but given the width of my room, would I need to add more insulsheild to the side walls than the standard 4' (or ear level) height? Also, when it's mentioned that the insulsheild is placed below ear level, does this ear level refer to those on the riser(s) or just those in the first row?


----------



## Ethan Winer

Proudx,


> So treatment is a room 13ft by 20ft would need to be more aggressive on the side and rear walls than in a room 20X25ft.


----------



## Dennis Erskine

Mancubus:


Haven't seen your room...but, I'd not suggest you use more Insul-Shield. I'd suggest you start six inches higher from the floor and bring the top higher.


Ear level...whether or not it's in the nose bleed seats or orchestra pit.


----------



## mark haflich

I disagree with Ethan. The closer you sit toward a rear wall, the more you need diffusion.


----------



## jschlege

Sorry to lower the tone of the conversation, but I'm a little confused about how this stuff is used. Is it a layer that would be placed over sheetrock (and then covered, for example, with GOM), or is it used in place of sheetrock? Or is it something else entirely?


----------



## Ethan Winer

Mark,


> I disagree with Ethan. The closer you sit toward a rear wall, the more you need diffusion.


----------



## Jeff Hovis

jschlege

I know how you feel. I stay semi-confused about acoustics all the time. I have some 4x8 Homasote that I bought from Home Depot. I'm going to use it on my front wall only. It's too expensive at nearly $18/sheet. I'll try to find something else for the sides.


This is a question for the experts: I'm placing mine over the sheetrock but shoud I place firring strips over the sheetrock first and leave a space or is it OK to screw it directly to the sheetrock. My screen and speakers are all 30" from the wall. Also, I see lots of HT sites that don't have fabric on the walls. I've also seen some in AV Interiors that really look like paint. I assume that it is not absolutely necessary to cover this stuff with fabric?

Jeff



> Quote:
> _Originally posted by jschlege_
> *Sorry to lower the tone of the conversation, but I'm a little confused about how this stuff is used. Is a layer that would be placed over sheetrock (and then covered, for example, with GOM), or is it used in place of sheetrock? Or is it something else entirely?*


----------



## gjlowe

My room is 14x20 with a drop ceiling at just under 8 feet. I plan on putting Linacoustic on the entire front wall (except where the screen is), from top to bottom on the first 2 feet on the side walls, and from ear-level down on the other three walls. I plan on painting the sheetrock on the upper half of the rest of the walls with some sort of treatment at the first reflection points of the front speakers. I also plan to use a thick carpet pad. Does this sound like effective treatments?


----------



## Ethan Winer

Jeff,


> I'm placing mine [homosote] over the sheetrock but shoud I place firring strips over the sheetrock first and leave a space or is it OK to screw it directly to the sheetrock.


----------



## jschlege

I guess I'm still a little confused. I was planning on using Insul-Shield. Is that installed on the studs like sheet rock, or over the sheet rock. I appreciate that you could probably set it off from the sheet rock and insulate in between, but that would give me insulation insul. shield over insulation over sheetrock over insulation, and I'm not sure I want to go there. If insul. shield can replace sheetrock, I would prefer just to do that (with the appropriate insulation behind.


----------



## BousquetP

Insulshield is placed over the sheetrock. Sheetrock is screwed to the studs.


Do some searches and you will find how all the acoustic treatments come together. The begining of this thread is a good start.


----------



## jschlege

Thanks. The begining of the thread has very useful information on placement/type, but not installation. I just need very basic installation info. for the acoustic treatments and GOM.


----------



## jmsun

All the comments have been very helpful. Although I have one question regarding corner treatment.

I am planning to put some corner bass traps in my HT. But at $500 each, It's not an option for me. Is there anything less expensive yet work as effectively? Thanks for your advice!


----------



## Ethan Winer

JS,


> The begining of the thread has very useful information on placement/type, but not installation.


----------



## David Bott

Ethan Winer...Please remove from your signature your link to your site and also please stop directing people to you for business. Please be so kind to re-read the rules of the site for this is not allowed on AVS Forum.


Thank you kindly.


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## two-rocks




> Quote:
> _Originally posted by jmsun_
> *All the comments have been very helpful. Although I have one question regarding corner treatment.
> 
> I am planning to put some corner bass traps in my HT. But at $500 each, It's not an option for me. Is there anything less expensive yet work as effectively? Thanks for your advice!*



google.com


Cut and paste (many links)!! 


DIY will save significant $, and [done properly] give the same result.


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## Ethan Winer

Mark,


> I disagree with Ethan. The closer you sit toward a rear wall, the more you need diffusion.


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## mark haflich

Having a need and being able to use are two different things.


Dr. D's rule of 3 times the lower limt wave length, is, to the most causual of observers, dependent on the lower cut off limit of the diffusor panel. I often use a 1 1/4 inch deep diffusor panel directly mounted onto the rear wall, all covered by Guilford fabric. Dr. D's panels are considerably deeper and correspondingly have a much lower cutoff, thus requiring that the listener be a further distance away from the wall to negate the adverse near field effects of a diffusor.


When a listener is close to a rear wall (the optimum design would indeed be different if there were 8 to 10 ft between the rear wall and the last row listener), the wall needs to be treated-not with heavy absorption and cetainly not with a bass trap (although the room may indeed need bass traping, try thr rear corners with a couple of bass traps (and I do not mean something labeled by some company as a bass trap but something tuned to pick up the room's specific bass resonance). Diffusion is what is indeed needed. But with a close wall position we want shallow depth diffusers or diffusers with a rather high lower limit. Here a diffuser could be such things as a bookshelf full of books, or some half round ASC tube traps with the reflective side out with a few inches of spave between each one (which would offer some absorption below 300 cycles), a rough sand paint wall etc. The point I am making is that you do not want a smooth hard reflective wall but you certainly do not want heavy absorption. You do not want a Dr. D difffuser because you would be sitting to close to it. Just some light diffusion.


----------



## LarryChanin




> Quote:
> _Originally posted by mark haflich:_
> 
> *When a listener is close to a rear wall, rhe wall needs to be treated-not with a lot of absorption and cetainly not with a bass trap (although the room may indeed need bass traping, try thr rear corners campers with a couple of bass traps (and I do not mean something labeled by some company as a bass trap but something tuned to pick up the rooms specific bass resonance). Diffusion is what is indeed needed. But with a close wall position we want shallow depth diffusers or diffusers with a rather high lower limit. Here a diffuser could be such things as a bookshelf full of books, or some half round ASC tube traps with the reflective side out with a few inches of spave between each one (which would offer some absorption below 300 cycles), a rough sand paint wall etc. The point I am making is that you do not want a smooth hard wall but you certainly do not wantabsorption to any extent. You do not want a Dr. D difffuser because you would be sitting to close to it. Just some mild diffusion.*



Mark and Dennis,


I'm in the process of designing a home theater with dimensions 24'x15'x10'. I want to place two equipment racks on the rear wall along with a little kitchenette with sink, microwave, below-counter refrigerator with a few wall and floor-mounted cabinets.


With the exception of the rear wall, I plan on using the acoustic approach typical of Dennis' designs with fiberglass on the front wall and front sides, and soffit. The rest of the side walls would be treated with fiberglass from ear level to the floor. However, in the rear of the room I've been considering some sort of diffusion since if left untreated the cabinets would be very reflective. I was toying with the idea of fastening half-round bamboo to the cabinets to serve as diffusers. An alternate absorption approach would be to hang heavy retractable drapes in front of all those reflective surfaces.


Short of forgetting about the kitchenette in the first place, do you have any opinions or recommendations regarding these approaches? The rear row of seating will be between 6 and 8 feet from the rear wall.


Thanks.


Larry


----------



## Dennis Erskine

Larry:


The bambo cabinet doors would provide diffusion. You could also use something like http://www.rpginc.com/products/topakustik/index.htm (reflector style) for your cabinet faces. With a handy table saw you could like build something similar.


----------



## LarryChanin




> Quote:
> _Originally posted by Dennis Erskine_
> *Larry:
> 
> 
> The bambo cabinet doors would provide diffusion. You could also use something like http://www.rpginc.com/products/topakustik/index.htm (reflector style) for your cabinet faces. With a handy table saw you could like build something similar.*



Hi Dennis,


Thanks for the suggestion. If you were using this approach on one of your designs would you first partially complete the room's standard acoustic treatments, then measure the room's response, and finally select the appropriate Topakustik product to fine tune the reverberation time, and other acoustic parameters?


Although these RPG products are listed as diffusor systems, the literature mainly discusses the absorption properties of the perforated styles. Does the reflector style provide significant amounts of diffusion?


For my design the cabinet faces would be 4 to 6 feet from the rear seating positions. Do you share Mark's opinion that as the listener gets closer to the rear wall diffusion makes more sense? Would you mind discussing the pros and cons of rear wall diffusion versus absorption with regard to rear seating location?


Thanks very much.


Larry


----------



## Ethan Winer

Mark,


I still don't follow your logic. If the last row of seats is closer to the rear wall than you'd like, it seems to me the goal should be to make the rear wall seem acoustically farther back. This is exactly what happens when the wall is made absorbent. There's no difference acoustically between a wall that is infinitely absorbent and one that is infinitely far away. Now, you might say the goal is _not_ to make it seem infinitely far away, but just somewhat farther back. Okay, but in that case...


> with a close wall position we want shallow depth diffusers or diffusers with a rather high lower limit. 
although the room may indeed need bass traping, try thr rear corners with a couple of bass traps (and I do not mean something labeled by some company as a bass trap but something tuned to pick up the room's specific bass resonance)


----------



## Dennis Erskine




> Quote:
> For my design the cabinet faces would be 4 to 6 feet from the rear seating positions.



But we're missing some critical data...how high above the floor are the cabinets...you have below counter cabs and above counter cab?



> Quote:
> Do you share Mark's opinion that as the listener gets closer to the rear wall diffusion makes more sense?



I neither share it or reject it. There's plenty of other factors to be considered...characteristics of the room, distance of the wall from the source, height of the source vs ear height vs wall height, etc., etc.


> Quote:
> Would you mind discussing the pros and cons of rear wall diffusion versus absorption with regard to rear seating location?



Again, there are no pros and cons, this is entirely a room dependent matter that would be studied during the design phase of a project.


I cannot say whether your room requires more or less absorption (for RT60 purposes) nor more or less diffusion. However, the product(s) I referenced can provide either absorption/diffusion or diffusion only. I believe the spec sheets can be downloaded from that page.


----------



## mark haflich

Once again, I agree with Dennis. Every room is different and that is why, if one is going to do it right, you need the services of an expert acoustician, I am not one! I do know where to go to get one or more, though my favorite is Norman Varney (I am biased, he is an old friend, too).


No, we haven't solved anything, Ethan, Every HT room to be optimized requires some strong absorption. Very broadband. This is required on the front wall, the front corners, and on the side walls (to kill the reflections between the LCR speakers and the listeners). That is every listener should hear these three speakers only directly and not also bounced off both side walls. That is very very clear.


HOWEVER, and note well, the side wall absorption need not go deep into the bass region. The 3db down point of the front speakers should be sufficient for this absorption. Elsewhere along the sides we do not want much if any absorption above 1000 HZ or so. Below 1000 hz we indeed want broadband absorption. You can go as low as you want here but there are practical reasons as to how low you can go. There are limits as to how much absorption you have room for in wall or on wall.


To deal with very low bass absorption by side wall treatment is generally not praticable. Dedicated broad band bass absorbers (say from 300 cycles down (upper mid bass and below). We need to depressurize the bass waves so they do not inhibit the ability of the front speakers to work optimumly. High bass back pressure will really screw the midrange up. Fact. Most rooms will have a bass resonance peak, A flat broadband absorper will tame this but the peak will still be there because of the other bass frequencies attenuation. So measure where the peak is is, or you can easily calculate what it will be from the room dimensions, and then treat it if is severe. Nothing really wrong with broad band bass absorption but it is not the end all.


By no means do we want rhe rear wall to be highly absorptive. That would be a very big mistake. The room will sound overly dead, decay times will go to hell and a handbasket. We want the wall to sound like it is relatively far away but seill there, and not like the listener is in an open field or an anachoic chamber. Diffusion (and many diffusors will absorb as well) is what is called for.


And not that I waqt to give everything away, but on the rear wall my mild diffusion goes on the upper half of the wall and below that I generally treat with broadband diffusion (below 1000 HZ). No reason this broad band can't be as low as you want. The lower rear wall is generally hidden acoustically by the seats so you can make it as dead as you want, Hide you deep bass absorption there if you want. Just do not make the wall above halfway up absorptive. OK you can have some absorption but mostly diffusion


----------



## formerly HTbuph




> Quote:
> _Originally posted by jmsun_
> *All the comments have been very helpful. Although I have one question regarding corner treatment.
> 
> I am planning to put some corner bass traps in my HT. But at $500 each, It's not an option for me. Is there anything less expensive yet work as effectively? Thanks for your advice!*



Jmsun,


See this thread,

http://www.avsforum.com/avs-vb/showt...hreadid=278701


----------



## dsinder




> Quote:
> A couple of minor points: diffusors do not affect RT60 in the manner described nor will they have any impact on standing waves.
> 
> 
> While vertical strips can create a moderate amount of diffusion, you cannot cover all the early reflection points to all seats effectively. In the 'ear level' scenario, you do have 'stuff' bouncing around above your head; but, if you watch your angle of incidence against where your speakers are placed (height), you've covered all the bases within the curve. This is also a much more effective method with rows of seating since you'll have more people close to the side/back walls than in a two channel, single seat of excellence environment.
> 
> 
> In multi-channel...no bad seats not one good seat.



Dennis,


In the deciding the height for the insulation on side and rear wall where should the refelection point for the front speakers to the listening positions be with respect to the top of the insulation? Above, at, or below? Which elememt of a 3way speaker to use as the reference?


Thanks


Dale


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## patrickwebb

Thought I would give this a bump as a great thread, thanks everyone!


----------



## jasplat88




> Quote:
> _Originally posted by Dennis Erskine_
> *The mirror method is "close enough for government work". Some thoughts:
> 
> 1. be sure the mirror is flat against the wall/floor/ceiling;
> 
> 2. consider all the seats (no bad seats);
> 
> 3. check height as well as distance down the wall;
> 
> 4. the tweeter is more critical than the woofer, none-the-less, your speaker or light bulb should be at the exact position of the speaker once installed (height, distance from wall etc.);
> 
> 5. recognize you are *not* interested in just the first reflections...it's early reflections which would include reflections from the wall behind the speaker (unless you're treating that surface).
> 
> 6. recognize that not all early reflections are bad...you're looking at the initial time delay gap along with the "Haas" effect, so "time" is more important than "first".*



Does this hold true when using Bi-Polar speakers for LR? Would the treatment of the front wall then change?


----------



## Terry Montlick




> Quote:
> _Originally posted by smithb_
> *
> 
> My plan is to treat the whole lower half (ear level and below) of the room as suggested (except full treatment on front wall). However, I have read mix messges on the value of using cloth covered batting on the top. Some say it is for acoustical purposes and some say that it just pushes the upper wall out to meet the treatments of the bottom half.*



Regardless of the intended purpose, polyester batting is a very efficient sound absorber. We have certified lab test data, but it is proprietary. Sorry!










Regards,

Terry


----------



## BasementBob

Polyester Acoustical Blanket Absorption Coefficients


inches mm 125 250 500 1000 2000 4000 NRC

1/2" 12.7 0.05 0.1 0.18 0.28 0.39 0.48 0.25

1" 25.4 0.08 0.18 0.33 0.49 0.61 0.66 0.40


from: http://www.jm.com/insulation/perform..._insultone.pdf 


For more polyester data, please see
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Dan Woodruff

patrickwebb,

Thanks for bumping this. Great information!


I have a question though . . . where is everyone buying their insulshield?


----------



## suffolk112000

This is a great thread...


I have a question.


How much of an acoustical difference will it make if I treat the upper walls and have painted sheet-rock on the lower three feet of the wall?

My thinking is, I have a 5 year old and sooner or later he or one of his toys will make its way through the GOM. Actually it just seems like it would be vulnerable to accidentally being kicked. My ceilings are 9+ feet tall and the room is going to be about 16X23. (Roughly)


Thanks


Craig


----------



## adamf

Craig,

The typical thinking is (in part) the "lower wall" treatments are to minimize the fronts first reflections (indirects) of the speakers back to your ears muddying up the sound due to timing differences. Where one draws the line how far up to go depends on multiple factors that others are more qualified to answer but one important one is how tall are your seats and the people who sit in them (ie ear level), vs tweeter/speaker level.


Good luck,

Adam


----------



## suffolk112000




> Quote:
> _Originally posted by adamf_
> *Craig,
> 
> The typical thinking is (in part) the "lower wall" treatments are to minimize the fronts first reflections (indirects) of the speakers back to your ears muddying up the sound due to timing differences. Where one draws the line how far up to go depends on multiple factors that others are more qualified to answer but one important one is how tall are your seats and the people who sit in them (ie ear level), vs tweeter/speaker level.
> 
> 
> Good luck,
> 
> Adam*



So this is a bad idea then? About 2/3 of the wall would be treated. Roughly three feet from the floor to the crown molding.

Thankns


Craig


----------



## Terry Montlick

Hi Craig,


Use the mirror method. If a mirror placed flat against the wall at your treatment area will reflect the front speakers when viewed from your sitting position(s), you are OK for early reflections from that wall.


- Terry


----------



## adamf

As Terry said....










One compromise would be to do the drywall as you note but use just a couple treatment panels mounted on the walls (sort of like long pictures) in select areas of the first reflections (ie those you see in the mirror from your prime seat/sweet spot). There are examples of this in several HT mags showing this concept/idea.


Good luck.


----------



## suffolk112000

Terry, adam... thanks!










Craig


----------



## jasplat88

My question was never answered, so I thought I would try again....


How does the acoustical treatment change (if at all) when you are using bi-polar speakers (Def's in my case)?


My guess is that the only change might be the treatment of the front wall. Would I then NOT want to treat the front wall OR would I want to treat the front wall with diffusion?


Also, Dennis or someone more familiar with it.....is the key to treating the side walls really only important for the ear levels of the listerners? Here's where I'm going with this.....can you INSTEAD of treating the ENTIRE bottom portions of the walls (as seen and described in this and many other threads) just treat a PORTION of the side walls (I am thinking of treating my walls similar to a racing strip on a car---i.e. the treatment would not go all the way to the floor. Would this provide the same benefit as treating the entire bottom below ear level?


I think this might be of benefit to others who don't or can't go back and retro-fit adjustable outlet boxes etc (although I installed them--I was merely thinking of others in this case). If this would provide the same results, it might be a way for others to achieve the same benefit without all the hassle of trying to modify or work around things that might not have been planned for.


It's a VERY crude illustration, but see attached for what I am talking about. Thanks for your help.


-Jason


----------



## Dennis Erskine

Jason:


There are two matters to consider when looking at placement of the acoustical materials:


1. The total amount of absorption across the frequency spectrum required to meet target reverberation times in the room; and,

2. The placement of those materials to address such considerations as early reflections, speaker boundary interface response, etc.


You can certainly create a "racing stripe" type of layout. On the other hand, if the entire wall is fabric covered (without regard to the colors, placement of colors, etc), there is no reason to restrict the placement of acoustic materials to match the layout of the fabrics.


Bipolar speakers would not be handled significantly different than dipolar other than perhaps placement of the speakers.


----------



## Jeff Hovis

Where in the Atlanta area can I purchase the Insul-Shield type insulation?


----------



## BasementBob

Dennis:


Way back on 05-04-03 in this thread in this post you wrote when given a choice between 1" and 2"


> Quote:
> I would not use the 2" material...it will very likely be too absorptive.



That has me very confused.


I thought that thicker made it more broadband (more lows), which is usually a good thing.

The only reason not to go with thicker I thought was economics -- it just costs twice as much to double the thickness.


----------



## Dennis Erskine

Jeff - The JM Coated Insul-Shield Black (or Theater Shield) is available from Alpha Insulation in Marrietta.


Bob - 2" is not enough for broadband (low frequency) applications when placed on a wall surface. On the other hand, in most of our rooms, using the 2" material provides more absorption than we need (or want). It is a balancing act. Once we determine all the absorptive surfaces we want and model 2" we're too absorptive.


----------



## Ethan Winer

Bob,


> I thought that thicker made it more broadband (more lows), which is usually a good thing.


----------



## Terry Montlick

I agree with you, Ethan.


Furthermore, if you cover a wall with an absorber which abuts other surfaces, there is no extra edge absorption effect like that in a reverberation room measurement. The absorption coefficients cannot go above 1, as when the edges are exposed. So the extra thickness simply extends bass absorption.


Regards,

Terry


----------



## krasmuzik

When you do the calculations for the other bass absorption in the room which likely cover


----------



## proudx

what is the most cost effective way to measure a rooms RT60 Value?


----------



## ChrisWiggles

proud: you can do it crudely, but cheaply with an impulse response program (i have a cheesy one if you want it), a cheap mic, and some loud noise like a clap, a wood clap, a starter pistol.


----------



## Dennis Erskine

As the fiberglass increases in depth, it's absorption characteristics at lower frequencies improves (the greater improvement occurs from 1" to 2"); however, one is wanting to achieve a reasonably uniform RT60 across the frequency spectrum requiring a balance in the materials utilized in the room. The would include the absorption characteristics of people in upholstered seats, unoccupied leather covered upholstered seats, gypsum board, etc. These are also small rooms where typical RT60 prediction models are less than reliable. In our experience, we find we're over absorbed in the general area of the 250-500Hz range with the 2" product


----------



## dochlywd

Maybe it's just me but.........I have always sat in the front middle seats of my theater(see my gallery) and thought that it sounds great. However, we had company over the other night and I sat in the left end seat which is turned slightly sideways to the front wall because of the curvature of the seating arrangement. I swear that I picked up more detail in this seat than ever before. Is this because the angle of seat (and my ears) changed the reflection points? If so, and it's not just in my head, than I definitely need to get some treatments on my walls. I swear I heard things in the movie that I hadn't before!


Dennis, do you know of anyone in St.Louis that can come out and do a reading for me? I have DIYed my entire theater and would like to build my own panels, but need someone to lay it out for me.


Thanks so much for all your help!


Mike


----------



## Dennis Erskine

Mike:


Gerry Lemay, founder of the Home Acoustics Alliance ( www.homeacoustics.net ) is based in the St. Louis area.


----------



## avare

Dennis:


I was always curious of your preference for 1" on the side walls. Thanks for the explanation!


Andre


----------



## Jeff Hovis

OK,

I had decided to use the OC703 but it is becoming a major pain to find it and once I did find it, the shipping was ridiculous. I assume Insul-Shield and Linacoustic are both similar products used for treating reflections. I'll now check DE's suggestion.


QUOTE]_Originally posted by Dennis Erskine_
*Jeff - The JM Coated Insul-Shield Black (or Theater Shield) is available from Alpha Insulation in Marrietta.


Bob - 2" is not enough for broadband (low frequency) applications when placed on a wall surface. On the other hand, in most of our rooms, using the 2" material provides more absorption than we need (or want). It is a balancing act. Once we determine all the absorptive surfaces we want and model 2" we're too absorptive.* [/quote]


----------



## Dennis Erskine

Jeff:


You can visit my showroom in Marietta and "hear" for yourself.


----------



## Jeff Hovis

Dennis,

I plan to do just that! I can only hope I don't spend too much money while I'm there.



> Quote:
> _Originally posted by Dennis Erskine_
> *Jeff:
> 
> 
> You can visit my showroom in Marietta and "hear" for yourself.*


----------



## jasplat88

It's been a couple of months and as members near this phase of their project this thread becomes VERY important....so BUMP!


----------



## 704set




> Quote:
> And yes, horse hair jute, in my many years of 2 channel experience, the best carpet pad for making a room sound good, is no longer commercially available. Too many "utes" were smoking it with bad side effects.



I guess it's back to the mushrooms.


----------



## fdlozano

I will be putting velvet curtains on the front wall all around the screen. The generally accepted wisdom is to treat the front wall to absorb as much sound as possible ("dead end").


Is the addition of heavy velvet curtains along the front wall negate the need to put sound panels behind the curtain?


Also, since the velvet is not acoustically transparent what use would putting acoustically transparent ("expensive") fabric over the panels should I choose to treat the wall.


----------



## GetGray

Hi Guys:


I read the entire thread and there was still one question that I think never got answered. And of course it applied to me, too







. My room:

Plan View 
View toward room front 
View toward room back 


It's larger than several discussed in the thread and my seating is not against the back wall.


It appears from this thread that I should:

1) Treat the screen wall top to bottom (linacoustic or equiv).

2) Treat some portion of the side walls.


I will have a drop tile ceiling in the area inside the soffit.

I will have a carpeted and padded floor.


My side walls due to construction and foundation issued will have a curtain wall with a shelf-cap instead of chair rail. That is, it's 2-walls thick at the bottom for lack of a picture). I have no need to put fabric on the upper section of the wall if not needed, it woudl be drywall. Is it necesary to use the upper treatment?


I have a lot of flexibility on the side curtain wall's height. Minimum 12" off floor, maximum - ceiling. I planned on about 4' all the way back. Maybe thats too much and I shoudl only do first reflection area?


For my elevated rear sofa, do I need to elevate the sidewall first reflection points, too?


I'm not sure but since my rear wall is relatively far away, should I treat it or not?


As for my soffits, how woudl one treat them? RIgid fiberglass panels covered with fabric on the floor facing part, or up the sides of the soffit's too?


With all this absorpion will the room be too dead?


Thanks,

Scott


----------



## Ethan Winer

FD,


> The generally accepted wisdom is to treat the front wall to absorb as much sound as possible ("dead end"). 
Is the addition of heavy velvet curtains along the front wall negate the need to put sound panels behind the curtain? 
since the velvet is not acoustically transparent


----------



## bpape

Curtains will do very little below very high frequencies. You still need to treat the front wall. The curtains do so little that it won't matter if they are in front of the treatments.


----------



## BasementBob

Actually, heavy curtains with a thick drape, covering 3.25 walls (floor to ceiling, rear wall, two side walls, some of front wall) can look very nice and have a huge effect on sound. Whether that is good or bad depends on the rest of the room. But you're right, even the best of them still absorb more highs than lows. But one can always put more absorbtion (wool and/or membrane) behind the curtains to extend into the low end and still look nice.



> Quote:
> 1105 Cotton curtains (0.5 kg/m2) draped to 3/4 area approx. 130 mm from wall (Ref. 17)
> 
> 0.3000 0.3000 0.4500 0.6500 0.5600 0.5900 0.7100 0.7100



Thin curtains with no drape are worse than carpet


> Quote:
> 1107 Curtains of close-woven glass mat hung 50 mm from wall (Ref. SBI/13)
> 
> 0.0300 0.0300 0.0300 0.1500 0.4000 0.5000 0.5000 0.5000


----------



## adamf

Scott,

The polybatting used on the upper half of rooms is usually just to provide a backing to keep the GOM or other fabric treatment even to the base. I don't believe Polyfill makes too much of a practical impact on diffusion/dispersion. Now whether you need treatments in this area (or around the soffits is a separate issue and depends on the RT60 and other features of your room. A couple well placed panels in the drywall areas once the room is built could be done to "tune" the room.


The first reflection points from your rear couch should be treated (theoretically) as that will improve the sound for those sitting there a well.


rear wall again varies. Most use dispersion/diffusion. I needed some increased deadening so I treated th bottom of my wall with soundselect. I do note some boomy base in the 2 back-corner seats and may some day try and find out what frequency and then apply a basstrap in those corners.


Dennis E. had addressed the soffit issue in the past, do a search in the builders area with soffit treatment and dennis's name and you might come up with it. Will try taking a look later if you can't find it.


Good luck,

Adam


----------



## GetGray

Adam:


Thanks, no batting on the upper area is good for me.


I will look into varying the height of my first reflection point treatment to accomodate the 2nd sofa.


I'll plan to leave rear wall alone for now, or roll the dice and cover the same as side walls.


I couldn't find anything helpful about the soffit treatments. If you think you know where to look I'd love to.


With my walls at almost 50% coverage, presmuably with soffits treated, my ceiling with acoustic tile, my floor with carpet, and my front wall at 100% treatment, should I expect the room to be too dead? bpape indicated it woudl go a long ways toward deading, but being new to this I don't know how much is too much.


Thanks,

Scott


----------



## Carlton Bale




> Quote:
> _Originally posted by JBS_
> *BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:
> 
> 
> Owens Corning Select Sound Black Acoustic Board
> 
> Owens Corning Fiberglas 703 Series duct insulation.
> 
> Johns Manville Insul-Shield
> 
> Johns Manville Linacoustic Permacoate rolls.
> 
> Certainteed Certpro Acoustaboard Black
> 
> Knauf Duct board EI-475
> 
> Knauf Duct liner EM
> 
> 
> ...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.*



OK, I've done quite a bit of reading and feel like I know where in the room to apply the acoustic materials. However, I have a very basic question about the materials themselves. Are some of these more like rigid boards and others more like blankets? If so, it looks like there should be two different categories, with one for boards and the other for blankets, as some people may prefer one over the other. Is the following break-down accurate?

*Board-style:*
Owens Corning SelectSound Black Acoustic Board 
Johns Manville Insul-Shield 
Certainteed Certapro Acoustaboard Black 
Knauf Duct board EI-475 


*Blanket-style:*
Owens Corning Fiberglas 703 Series duct insulation 
Johns Manville Linacoustic Permacote rolls 
Knauf Duct liner EM 
Owens Corning SelectSound Black Acoustic Blanket


----------



## fdlozano

Ethan,


I over generalized in my original post. I've been reading alot of the posts here about acoustics and about LEDE, first, second reflections, etc. I've seen quite a few theaters from posters on this site that put either insul-shield or OC 703 panels or similar material along the front wall (Dead end) and cover that with acoustically transparent fabric. I was planning on starting with the front wall and then move to the side and rear walls as time and money allow. I was intending for the panels along the front wall behind the heavy velvet curtain to absorb high frequencies only. I intend to build bass traps like Jon Risch's to cover the low end.


Regarding putting panels of OC 703 or similar material, What I REALLY want to find out is if I still need to put panels behind the heavy velvet curtains. It looks like I do not need to based on the numbers that Basement Bob posted regarding cotton curtains. I could and probably am wrong.


If I do put panels behind the curtains, would I still need to go through the expense of putting acoutically transparent fabric over the panels? I would think that since the curtains are NOT acoustically transparent that it would be a moot point. Again, I could be wrong.


I willingly bow the massive collective wisdom of the people who frequent this great site for help. Thanks again for the replies!


----------



## BasementBob

fdlozano:



> Quote:
> What I REALLY want to find out is if I still need to put panels behind the heavy velvet curtains. It looks like I do not need to based on the numbers that Basement Bob posted regarding cotton curtains.



Those examples were the best and worst absobtion figures for curtains that I found. And even the best, the heavy cotton ones that are way out from the wall and huge drape, still absorb a lot more in highs than in lows.


OK, let's talk about what's going on here.


We've got modes, flutter, and SBIR (first reflection).


Curtains will do wonders for flutter.

Curtains will do nothing perceptable for modes.

Curtains will do a bit for side reflections (mid and high), but nothing for SBIR reflections off the front wall (which tend to be louder lower).


DE designs seem to have about 1" of linacoustic or InsulSheildBlack for the front wall. ( 0.09 0.29 0.67 0.89 1.03 0.99 ).

If you have lots of couches and thin walls then some of your modal issues may already be handled.


In the stereo control room world there are two designs for front speakers - baffles and thick absorbtion on the front wall on either side of the speakers. Either handle SBIR.


LEDE may not be appropriate for small rooms, unless you're doing a dual purpose room which is also for playing musical instruments.


OK, you want a bit of a dead room from all sides for 7.1

But you don't want to absorb everything because it has three bad effects:

1) it's expensive

2) it requires you to turn up your amplifier possibly to the point of distortion

3) it removes the reflected sound which is needed for spaciousness


So what you're really after is

a) absorb first reflections and SBIR for the best imaging

b) a flat RT60 (even absorbtion at all frequencies)

c) Any reflection path less than 20ms you might want to absorb or diffuse so that it hits the listener area down about 30db or more relative to the direct sound.



> Quote:
> If I do put panels behind the curtains, would I still need to go through the expense of putting acoutically transparent fabric over the panels? I would think that since the curtains are NOT acoustically transparent that it would be a moot point.



You got it. Curtains over absorbers are fine.


----------



## bpape

Yes. You should still put other absorbtion behind the curtains. When you cover the panels, just make sure it is a somewhat porous, non-shiny finish material. Muslin does wonderfully. The idea of the panels is to absorb. Don't cover them with a cloth that reflects and you'll do fine.


----------



## jasplat88

I agree with bpape and based on discussions with Dennis, you STILL will want to treat the front wall. You will also want to treat the first reflection points on the side walls, but it sounds like you plan on doing that anyways.


Ethan, I'm curious as to why you disagree with Dennis and others about treating the front wall. I've seen you state this in another thread---most recently above where you said "Not necessarily." in reference to the generally accepted practice of doing this in a Home Theater enviroment. It appears you disagree with this statement by Dennis from this thread :


"In multi-channel, the entire wall behind the front speakers is treated. You want none of the back reflections to overlay the surround field or the bring the reverberent field forward (your reverberent field and surround field is created by the multi-channel processor or mix, not so much the room as is mandatory for 2-channel). Depending on speaker placement, this treatment is brought forward along the side walls. Wall treatments are floor to slightly above ear level (where exactly is also a function of front speaker heights). While one could argue the sound at their feet is of no concern, often that square footage of treatment is required to bring the room's RT60 down to the lower levels required for multi-channel playback."


Actually after re-reading that thread....I see YOU (Ethan) asked Dennis the front wall treatment question here:


"Dennis,


> recognize you are *not* interested in just the first reflections...it's early reflections which would include reflections from the wall behind the speaker (unless you're treating that surface).


----------



## bpape

I believe what I said in the other thread was that with carpet, acoustic tile ceilings and 50% wall coverage, the room would likely be too dead in the upper frequencies and still too live at lower ones.


----------



## GetGray




> Quote:
> I believe what I said in the other thread was that with carpet, acoustic tile ceilings and 50% wall coverage, the room would likely be too dead in the upper frequencies and still too live at lower ones.



Thank you for the clarification, that helps me understand what the problem might be anyway. If I have to stay with carpet and ceiling, what woudl be a course of action then? Wall treatment only at first reflection points? or just less overall treatment at some percentage of coverage? Then bass traps for lows? Would a drywall ceiling cure or help the overdeadened highs? Or what?










Thanks,

Scott


----------



## Terry Montlick

From the perspective of early reflections, it is generally not necessary to treat the front wall. A commonly cited figure for the sound level at which early reflections cause imaging shift problems is 10 dB below the level of the direct sound. This is the recommendation chosen by a few professional organizations.


Looking at the directivity patterns of typical baffled loudspeakers, the rear sound radiation does not reach -10 dB at medium to high frequencies. Non-directional low frequencies are too broad to contribute early reflection "spikes" to the impulse response. So the possibility of a -10 dB early reflection from the front wall of a home theater is pretty low.*


If you are acoustically treating a home theater room, the front wall is a readily available surface which, if treated, will help lower reverberation time. Also, the same research which showed that an approximately -10 dB reflection is necessary to shift the image away from a speaker also showed that lower levels can be perceived as changing the sound.


Any reflections from the front wall, while not usually causing specific acoustical harm, can do no good. It is not a hard and fast rule to treat the front wall of a home theater. It is generally just a good idea -- a no-brainer if your theater design allows it.


Regards,

Terry


* If you are using an "acoustically transparent" microperforated projection screen in front of speakers, this can bounce significant high frequency energy toward the front wall, which will reverberate between screen and front wall if not absorbed. In this case, front wall treatment is mandatory, IMHO.


----------



## Dennis Erskine

SBIR is something different than "early reflections". None-the-less, have speakers (various from speaker to speaker) near a boundary can have unfortunate side effects unless that boundary (or the speaker) has been modified to adjust (or eq is used). It is a great place for absorption to achieve RT60 targets as Terry noted.


Whether or not the reflected sound from the front wall surfaces will be perceived as an echo or 'fused' to the direct sound will depend again, on speaker distance from the boundary. HAAS effects not withstanding, such out of phase early reflections can have a negative impact on intelligibility.


Flutter echo is seldom a problem in a home theater as is isolated to only a few seating locations should it occur. None-the-less, front wall absorption will reduce the opportunity for flutter echo to become an issue.


----------



## jasplat88




> Quote:
> _Originally posted by Terry Montlick_
> *Looking at the directivity patterns of typical baffled loudspeakers, the rear sound radiation does not reach -10 dB at medium to high frequencies. Non-directional low frequencies are too broad to contribute early reflection "spikes" to the impulse response. So the possibility of a -10 dB early reflection from the front wall of a home theater is pretty low.**



Terry,


Thanks for your take on the front wall treatment. I guess in my particular case (having bi-polar mains) where the front wall has speakers directed at and bouncing off of it, it becomes even more important to treat the front wall. Regardless of speaker design, you basically said the same thing Dennis said and what I and bpape stated above.....treat the front wall! It still doesn't answer my question as to why Ethan disagrees with this. I can guess that he might think that treating that large of a surface will deaden a room too much and cause even muddier (if that's even a word) bass...but that's what I am trying to find out.


It's helpful (at least for me) to seperate room acoustic treatments in two categories: high and mid treatments (i.e. 703 and the like) and bass treatments/traps. The front wall treatment I am curious about (with regards to Ethan) is the high and mid treatment of the front wall.


-Jason


----------



## bpape

Drywall ceiling will significantly reduce the amount of high frequency absorbtion. Look at the square footage of the ceiling in relation to the square footage of all the room's surfaces.


If you stay with tiled ceiling, you might do more scattered absorbtion and hit the reflection points. It is a good thing to have absorbtion throughout the room for more effective decay control. Do some calculations on what you think your room will be like. There is a spreadsheet floating around from Eric Desart that has a lot of good stuff in it regarding decay time calculations. Fill in the blanks and see where you fall at given frequencies. You'll see quickly where you still need help.


----------



## CPanther95

Threads Merged


----------



## nirvana_av




> Quote:
> _Originally posted by Terry Montlick_
> *From the perspective of early reflections, it is generally not necessary to treat the front wall. A commonly cited figure for the sound level at which early reflections cause imaging shift problems is 10 dB below the level of the direct sound. This is the recommendation chosen by a few professional organizations.*



Exactly. High frequency, off-axis response is significantly attenuated. Tweeters, typically above 2.5k-3k Hz have dispersion patterns like flashlights. The point where midrange off-axis response is only 6dB down can be as low as 200 Hz.


----------



## nirvana_av




> Quote:
> _Originally posted by jasplat88_
> *Thanks for your take on the front wall treatment. I guess in my particular case (having bi-polar mains) where the front wall has speakers directed at and bouncing off of it, it becomes even more important to treat the front wall.*



Don't you mean dipole mains? Dipole mains (open baffle speakers), by design, rely on the contribution of the backwave. That is why proper placement is critical.


----------



## jasplat88




> Quote:
> _Originally posted by nirvana_av_
> *Don't you mean dipole mains? Dipole mains (open baffle speakers), by design, rely on the contribution of the backwave. That is why proper placement is critical.*



Well in my case I actually meant bi-polar (I own Def Tech BP2000's). But in either a bi or di-polar situation my point is still vaild (I think the only main difference between bi and di-polars is the drivers opperate out of phase in a di-polar setup and in phase in a bi-polar setup---but I might be wrong). The point I was making is now you definitely have early reflection points off the front wall and it's still important to treat it (the front wall).


-Jason


----------



## krasmuzik

But if the speaker was designed for bipolar operation - are you not destroying the speaker designers intended sound by covering up the front wall?


Why use the bipoles then - best go for monopole! In other words - if reflections are bad - then why choose a speaker that is designed for reflections?


----------



## nirvana_av




> Quote:
> _Originally posted by jasplat88_
> *Well in my case I actually meant bi-polar (I own Def Tech BP2000's). But in either a bi or di-polar situation my point is still vaild (I think the only main difference between bi and di-polars is the drivers opperate out of phase in a di-polar setup and in phase in a bi-polar setup---but I might be wrong). The point I was making is now you definitely have early reflection points off the front wall and it's still important to treat it (the front wall).
> *



Ah, the Def Techs. Some of the top-end Wilsons do this with a tweeter on the back. I might be wrong, but I think the point of this alignment is to improve imaging and "space". I would agree with Kras, they might not be the best for an HT application.


----------



## jasplat88

From a acoustical treatment (in regards to the front wall) standpoint, I already asked this question and was provided the following answer by Dennis:


"Bipolar speakers would not be handled significantly different than dipolar other than perhaps placement of the speakers." (see page 6 of this thread)


I realize some people THINK these speakers are not ideal for HT.....I happen to THINK they are. That's why there are so many manufacturers of speakers....so people can pick and choose what they like










-Jason


----------



## krasmuzik

The point is that that the rear facing tweeter of a bipolar (or dipolar) speaker is useless if the front wall is absorbing those treble frequencies. It essentially becomes a monopole.


If you like the bipolar (or dipolar) sound - then you should NOT treat early reflections. You are wasting money on an unused tweeter if you do treat.


----------



## nirvana_av

With the Def Tech, you're not just wasting the tweeter, you're pretty much wasting a whole MTM.


----------



## jasplat88




> Quote:
> _Originally posted by krasmuzik_
> *The point is that that the rear facing tweeter of a bipolar (or dipolar) speaker is useless if the front wall is absorbing those treble frequencies. It essentially becomes a monopole.
> 
> 
> If you like the bipolar (or dipolar) sound - then you should NOT treat early reflections. You are wasting money on an unused tweeter if you do treat.*



Kras...I am well aware of your version of "the point".... however, you are wrong. Treating the front wall with 703 or similar WILL NOT absorb 100% of the sound from the rear facing tweeters and drivers, and warrant them "useless." It will help tame them, which is what I want. I have yet to hear a speaker that sounds as good as the Def's I have. If achieving the sound I like is "wasting my money" oh well, I can live with that. BTW, it's NOT the sound of bi-polars or di-polars that I like....it's the sound of Def Techs.


It's the Holidays....you need to stop being so Anti-Def Tech and live a little!


-Jason


----------



## jasplat88




> Quote:
> _Originally posted by nirvana_av_
> *With the Def Tech, you're not just wasting the tweeter, you're pretty much wasting a whole MTM.*



Oh well....I guess I will have to rip them out (the rear facing MTM's) and sell them on Ebay to retrieve some of my wasted money


----------



## krasmuzik

From BasementBob's web page.


Product thickness density mounting 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC


703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00


Ignoring the excess absorption of exposed edges which will not occur with a covered wall - OC703 absorbs pretty much 100% of the treble frequencies. Of course an absorption coefficient like this has insufficient accuracy to tell you how many -dB down the reflection will actually be.


I never said anything negative about Def. Tech speakers (my opinion of bipolar front speaker is irrelavent to this discussion). The point is if YOU like the expansive reverberant sound-stage that a rear facing bipolar gives you - treating the wall to absorb treble makes that sound-stage go away.


If you want to just tame that sound-stage a bit and like the bipolar sound - then use a less aggressive absorption scheme that leaves some % of that front wall facing reflective.


----------



## jasplat88

Kras,


I'm not using 2" 703 and Dennis does not recommend using 2" material as it absorbs too much (but I'm sure you knew this if you have already read this thread--it's in his third post on the first page). I am using a 1" equilivant (it's not 703), and it does not absorb the entire high end frequency and even less in the mids.


Not that's it's important, but I did set up the 1" ductboard and spent a few hours listening to different music and movies with and without the 1" material on the front wall before I permanently covered it, and I do prefer it treated.


-Jason


----------



## krasmuzik

Well OK 1" maybe down 10% at 1KHz - but the higher frequencies are still pretty close to 100% absorption - at least with the Linacoustic numbers I see on BasementBob's page. The difference with the thinner stuff is at mids at 250-500Hz.


IS Black 1" (25mm) 1.5pcf (24kg/m3) 0.09 0.29 0.67 0.89 1.03 0.99 0.70

Linacoustic RC 1" (25mm) 0.08 0.31 0.64 0.84 0.97 1.03 0.70


So I still maintain that you like it because the bipolar has been converted to monopolar (or technically a directional front firing tweeter)- at least in treble frequences the back wall wave is being absorbed.


----------



## jasplat88




> Quote:
> _Originally posted by krasmuzik_
> *So I still maintain that you like it because the bipolar has been converted to monopolar (or technically a directional front firing tweeter)- at least in treble frequences the back wall wave is being absorbed.*



Kras,


You may be correct, but I maintain that I still like the way my Def's sound even over other monopoles....so oh well.


The point I was making was......in general, the front wall of a HT should be acoustically treated. Period!


----------



## nirvana_av

Kras is just making some valid technical points here. If the speakers work for you, then that's great. Enjoy. Given the HT application and desire for front wall treatment, it simply wouldn't be advisable for the next guy who's shopping around for speakers.


----------



## Dennis Erskine

One must understand the genesis of speaker designs with a significant amount of "back radiation" or "back wave" (bipolar, rear firing tweeters, etc.) Back in the two channel only days, the only way to create room filling spaciousness was to rely upon reflected sound throughout the room. On method of augmenting this was to make better (more?) use of the front wall...which also helped fill the coverage hole in the middle.


You can get excellent sound stages with treated front walls and even better sound stages with three channels. In the multi-channel world it is most often very counterproductive to use such designs...effectively using your room as a surround processor...since ambiance extraction techniques and multi-channel recording can do a much better job.


(...and, I invite anyone to come and hear this in our demo facility in Atlanta)


----------



## Ethan Winer

FD,


> What I REALLY want to find out is if I still need to put panels behind the heavy velvet curtains.


----------



## Ethan Winer

Jason,


> I'm curious as to why you disagree with Dennis and others about treating the front wall


----------



## Kal Rubinson




> Quote:
> _Originally posted by Ethan Winer_
> *I still have not gotten around to measuring the free-field response of my Mackie HR624, and I plan to do that eventually. I'm not convinced that loudspeakers radiate a significant amount of mids and highs out the rear (or that mids and highs wrap around) enough to worry about treating the front wall. Listening rooms I've been in that had absorption over the entire front wall always sounded too dead to me.
> 
> --Ethan*



I see a conundrum here, Ethan. If there is minimal direct radiation of mids and highs to the front wall, why does treating it make the room too dead? Of course, it may be that anyone who covers the entire front wall has also put too much treatment elsewhere.


Kal


----------



## Ethan Winer

Kal,


Sorry, I was still editing/adding while you were replying.


> If there is minimal direct radiation of mids and highs to the front wall, why does treating it make the room too dead? Of course, it may be that anyone who covers the entire front wall has also put too much treatment elsewhere.


----------



## Kal Rubinson

OK. So are you saying that concentrating it on the front wall deadens more than spreading it around? What I am really asking is why the front wall is any more or less effective a site for mid-, hi- absorbtion if its proximity to the speakers is not an issue?


Kal


----------



## Ethan Winer

Kal,


> So are you saying that concentrating it on the front wall deadens more than spreading it around? What I am really asking is why the front wall is any more or less effective a site for mid-, hi- absorbtion if its proximity to the speakers is not an issue?


----------



## Dennis Erskine

Kal:

In the overall scheme of things, deadens more or less is less a function of placement than it is a matter of the total amount of absorption (and characteristics) in the space. In small rooms, placement of absorption becomes significantly important. Now with respect to your specific question above, the answer becomes "well that depends". While you elminated the proximity issue to the front wall, we have other factors to consider...for example distance to side and rear walls as we manage not only room reverberation times but path differences and their related effects. Typically, however, as long as you're NOT using full range speakers, you'll find the L/C/R in the 3' range from the front wall...then considering the other issues, the front wall becomes a very effective place for absorption.


----------



## Dennis Erskine




> Quote:
> You get obvious echoes off the rear wall, floor to ceiling flutter echo if there's no carpet, and also flutter echo between the side walls where they're not treated



You may have an overly reverberant space; but, flutter/slap echoes will not be the issue (unless you have a speaker on the floor or ceiling, this cannot happen).


----------



## SanchezGZ

Dennis how far is your business from Buckhead? I will be in Atlanta late January early February....


Edit for not reading before posting:

What happens Dennis in the case that your L/R are full range?


----------



## GetGray




> Quote:
> The front wall is no less effective than any other surface if the goal is to reduce ambience generally. But treating the entire front wall and leaving the entire rest of the room reflective gives an unbalanced sound. You get obvious echoes off the rear wall, floor to ceiling flutter echo if there's no carpet, and also flutter echo between the side walls where they're not treated.
> 
> 
> All of this depends entirely on the room in question! There are tiny rooms and huge rooms, so that too is a factor. I'm speaking in general terms about smallish rooms like you find in most homes.
> 
> 
> --Ethan



Ethan:


Then can you offer a suggestion on a good starting point for this room for treatment? I was planning on entire front and 42" of side all the way around. Floor=carpet, ceiling=tile, soffit=drywall.

http://www.mlec.net/scott/HTBigRoom1.gif 
http://www.mlec.net/scott/HT3DNorth.jpg 

Thanks,

Scott

The more I listen the less I know


----------



## rontron

I am finishing out our basement and am putting a theater/ media room down stairs. Due to family consideration I cannot dedicate the space to just a theater. I was thinking about using a curtain on a track as a means of "creating" a back wall when i want to watch a movie. The benefit of course would be that when the theater is not in use the curtain could be pulled back, opening the whole space. The question is what would the effects be of the curtain on the acoustics of the room? Thanks for your help!!


Ron


----------



## ChrisWiggles

The curtain is a great idea for light control, but it will absorb a lot of HF and do nothing about the bass. Bass traps or thicker panels elsewhere behind the curtains can help with the bass absorption.


----------



## Dennis Erskine




> Quote:
> Dennis how far is your business from Buckhead? I will be in Atlanta late January early February....



About 11 miles north.



> Quote:
> Edit for not reading before posting:
> 
> What happens Dennis in the case that your L/R are full range?



As you move a speaker closer to the wall the SBIR notch frequency increases. With non-full range + a subwoofer, you can move the sub toward a boundary to raise the notch frequency above 80 Hz. You move your mains out from the wall (about 3') to move the notch below 80 hz. With full range, your speakers need to be on the order of 15 feet from any boundary. Further, the locations required for your main speakers to achieve the best imaging will not be the best location for LF to achieve smooth bass response in the room.



> Quote:
> but it will absorb a lot of HF and do nothing about the bass. Bass traps or thicker panels elsewhere behind the curtains can help with the bass absorption.



But you also have a much larger room from a bass point of view so you must deal with modal response, smooth bass reponse, and amplifier power based upon the larger space.


----------



## HuskerHarley

I've noticed a lot of abbreviations used in the Home Theater section of AVS, is there a sticky or a Faq somewhere that has the definitions?


HH


----------



## Terry Montlick

Since Dennis brought up the SBIR (Speaker-Boundary Interference Response), some of you may be wondering how to measure it. You can do this with a program like ETF.


The idea is based on the fact that SBIR is a short-time effect. It happens within the first tens of milliseconds of the sound, where 1 millisecond = about 1 foot of sound travel. So if you take the frequency response using a short impulse-response time window (20 milliseconds or so), you will see what is going on during the time period when the direct sound from the speaker interferes with its reflection from a nearby wall.


On the other hand, if you look at a long-term frequency response (time window of a hundred or more milliseconds) it will span several wall reflections back and forth through the room. You now see the effects of room modes added to the SBIR, since the modes need time to build up over several wall reflections. Get it?


Now, there is one gotcha. With a small time window, you automatically get less detail in the frequency domain. It is a fundamental trade-off in the signal processing world. So if you set the time window to 20 milliseconds for example, you won't see any frequencies below 50 Hz. ETF will show you a smooth response above this, but there is still limited low frequency information, and you will not see a lot of detail. Nevertheless, you still should be able to spot any dip corresponding to the 1/4 wave cancellation which Dennis described.


Apologies to those for whom this discussion was too technical, but it seemed like a good opportunity to explain more about the "mysterious" SBIR.


- Terry


----------



## LarryChanin




> Quote:
> _Originally posted by Dennis Erskine_
> *As you move a speaker closer to the wall the SBIR notch frequency increases. With non-full range + a subwoofer, you can move the sub toward a boundary to raise the notch frequency above 80 Hz. You move your mains out from the wall (about 3') to move the notch below 80 hz. With full range, your speakers need to be on the order of 15 feet from any boundary. Further, the locations required for your main speakers to achieve the best imaging will not be the best location for LF to achieve smooth bass response in the room.*





> Quote:
> _Originally posted by Terry Montlick_
> *
> 
> Since Dennis brought up the SBIR (Speaker-Boundary Interference Response), some of you may be wondering how to measure it. You can do this with a program like ETF.
> 
> 
> The idea is based on the fact that SBIR is a short-time effect. It happens within the first tens of milliseconds of the sound, where 1 millisecond = about 1 foot of sound travel. So if you take the frequency response using a short impulse-response time window (20 milliseconds or so), you will see what is going on during the time period when the direct sound from the speaker interferes with its reflection from a nearby wall.
> 
> 
> On the other hand, if you look at a long-term frequency response (time window of a hundred or more milliseconds) it will span several wall reflections back and forth through the room. You now see the effects of room modes added to the SBIR, since the modes need time to build up over several wall reflections. Get it?
> 
> 
> Now, there is one gotcha. With a small time window, you automatically get less detail in the frequency domain. It is a fundamental trade-off in the signal processing world. So if you set the time window to 20 milliseconds for example, you won't see any frequencies below 50 Hz. ETF will show you a smooth response above this, but there is still limited low frequency information, and you will not see a lot of detail. Nevertheless, you still should be able to spot any dip corresponding to the 1/4 wave cancellation which Dennis described.
> 
> 
> Apologies to those for whom this discussion was too technical, but it seemed like a good opportunity to explain more about the "mysterious" SBIR.
> 
> 
> - Terry*



Hi Dennis and Terry,


Thanks for the great information on a subject that, as Terry notes, is rather mysterious to the layperson.


I have been attempting to use EFT to aid in selecting my crossover points. I've been using a long time window and comparing the logarithmic frequency responses of various pairs of crossover points for my mains and LFE subwoofer. Based on this long time window it appears to me that selecting 60 hz for my mains and sub yielded the smoothest frequency response. However, based on your information it would appear that I am missing the short time effects of Speaker Boundary Interference. Should I be attempting this with a 20 ms time window? I realize I won't see the lowest bass response, but I assume the object would be to see how smooth I can get the responses at the crossover points?


Due to practical trade-offs of accommodating a moderately sized non-perforated screen, my floor standing main speakers are located less than the ideal distance from the side walls. The manufacturer's instructions recommend maintaining more than three feet from the side walls to the sides of the speaker cabinets. The sides of my speakers are 1'4 from the side walls or 2' from the walls to the center of the bass driver. (Surprisingly they state that the back of the speaker cabinet are permitted to be as close as 1-1/2 from the front wall. The back of my speakers are about 5 from the front wall.)


I have 1 of fiberglass on the front and side walls. Given that I can't change the horizontal orientation of the mains, is there anything I can do to mitigate SBIR effects?


Would merely setting the crossovers higher tend to overcome these effects?


In addition, would filling the space between the speakers and the side walls with rolls of my left-over 1 fiberglass be helpful? If so, since my overall reverberation time measures fairly low, would it be wise to cover the rolls with paper or some other reflective covering to avoid further reductions in the higher frequency reverberation times?


In order to center my main's tweeters vertically on the screen, I have placed them on concrete blocks. However, that puts the centers of the bass drivers at the same distance to the stage floor as they are from the side walls. Do these common dimensions aggravate SBIR effects?


Thanks in advance.


Larry


----------



## kromkamp




> Quote:
> _Originally posted by Dennis Erskine_
> *As you move a speaker closer to the wall the SBIR notch frequency increases. With non-full range + a subwoofer, you can move the sub toward a boundary to raise the notch frequency above 80 Hz. You move your mains out from the wall (about 3') to move the notch below 80 hz. With full range, your speakers need to be on the order of 15 feet from any boundary. Further, the locations required for your main speakers to achieve the best imaging will not be the best location for LF to achieve smooth bass response in the room.
> *



In my room I have full-range towers and am forced to put them approx 14" from the sidewalls. I also measure using ETF a null at ~220Hz. This to my thinking is SBIR (1130/(220*4) = ~15"). Where would wall treatment go to correct this - directly to the sides of the speakers, or more towards where the first reflection points are?


I did try heavily trapping the side walls beside the speakers with 2" fiberglass at one point, and it made the speakers sound dead. However, I may have used too much of it. I just checked my speaker specs - the woofer crossover is at 250Hz. I may try just treating the wall down low where the woofer is.


From a general point of view, do you recommend non-full range + sub even for 2-channel audio?


Thanks,


Andy K.


----------



## LarryChanin




> Quote:
> _Originally posted by kromkamp_
> *In my room I have full-range towers and am forced to put them approx 14" from the sidewalls. I also measure using ETF a null at ~220Hz. This to my thinking is SBIR (1130/(220*4) = ~15").*



Hi Andy,


What did you set your time window for your measurement?


Thanks.


Larry


----------



## Terry Montlick

Larry -

The idea with the crossover frequency and SBIR is to arrange sub and main speaker so that neither generates an audible 1/4 wavelength frequency. Just a simple calculation based on speaker distance to the wall is necessary.


Take the distance of the speaker or subwoofer to the wall in feet, and divide 282.5 by this distance. (282.5 = 1130 feet/sec, the speed of sound at room temperature, * 1/4 wavelength). The result is the frequency in Hz that would generate 1/4 wave cancellation.


This frequency calculated for your subwoofer, should be above the crossover point. This frequency calculated for the mains should be below the crossover point. Then, both sources completely avoid the problem.


Andy -

Wall treatment should be centered around the first reflection points, but it also needs to cover a broad area since the wavelength is relatively large. Without doing the math, I would guess that dimensions of 1/2 wavelength, or around 30", would be pretty safe.


One idea would be using a narrow tuned bass absorber for this specific frequency. That way, it will not affect the overall sound that you like. A 220 Hz tuned bass absorber (either Helmholtz or limp acoustic mass panel) shouldn't require a great deal of physical depth.


- Terry


----------



## LarryChanin




> Quote:
> _Originally posted by Terry Montlick_
> *Larry -
> 
> The idea with the crossover frequency and SBIR is to arrange sub and main speaker so that neither generates an audible 1/4 wavelength frequency. Just a simple calculation based on speaker distance to the wall is necessary.
> 
> 
> Take the distance of the speaker or subwoofer to the wall in feet, and divide 282.5 by this distance. (282.5 = 1130 feet/sec, the speed of sound at room temperature, * 1/4 wavelength). The result is the frequency in Hz that would generate 1/4 wave cancellation.
> 
> 
> This frequency calculated for your subwoofer, should be above the crossover point. This frequency calculated for the mains should be below the crossover point. Then, both sources completely avoid the problem.
> 
> *



Hi Terry,


Thanks for the response.


When measuring the distance from the speaker or subwoofer to the wall, are we measuring from the center of the bass drivers, or the side of the cabinet nearest the wall?


Thanks.


Larry


----------



## Terry Montlick




> Quote:
> _Originally posted by LarryChanin_
> *
> 
> When measuring the distance from the speaker or subwoofer to the wall, are we measuring from the center of the bass drivers, or the side of the cabinet nearest the wall?
> *



Center of the bass drivers, mostly. There will be diffraction at the edges of the cabinet which will create secondary sound sources, but these will be lower in volume.


However, in the case of a side wall, you need to consider the time DIFFERENCE between direct and reflected sound, since the sound is not reflecting at right angles as it would be (more or less) from the front wall. Use the tape measure technique that Dennis suggested to determine this difference.


CORRECTION: When using the measured difference method, use 1/2 the wavelength, not 1/4 the wavelength. This means dividing 565 (2*282.5) by this distance difference.


- Terry


----------



## jasplat88

Is there is general forumla or theory on what % of sq/ft needs to be covered with (1") acoutic treatment to achieve correct RT60? Or is this just WAY too dependent on too many moving variables? Basically I am looking to see if it is generally accepted that treating the front wall and ear level down to floor on the side walls in most HT's is appropiate does that equate to ~30-35%? More? Less? Any general rules that would be helpful in getting close (or in the ballpark) without measuring?


-Jason


----------



## bpape

You can use some of the better spreadsheets and calculate it based on all of the materials in the room. It's far from exact but will get you in the ballpark.


How much you cover and in what depends so much on furnishings, concrete or wood subfloor, wall construction, # of people, etc. that it's awfully hard to give even a ballpark number. Also, the 'correct' RT60 is dependent on what you want to do with the room. The correct number is different for music listening than it is for HT.


----------



## LarryChanin




> Quote:
> _Originally posted by Terry Montlick_
> *Center of the bass drivers, mostly. There will be diffraction at the edges of the cabinet which will create secondary sound sources, but these will be lower in volume.
> 
> 
> However, in the case of a side wall, you need to consider the time DIFFERENCE between direct and reflected sound, since the sound is not reflecting at right angles as it would be (more or less) from the front wall. Use the tape measure technique that Dennis suggested to determine this difference.
> 
> 
> CORRECTION: When using the measured difference method, use 1/2 the wavelength, not 1/4 the wavelength. This means dividing 565 (2*282.5) by this distance difference.
> 
> 
> - Terry*



Hi Terry,


Thanks.


Just to be sure I know what you mean by Dennis' tape measure technique I've attached a crude diagram showing the speaker, listener and walls. The object is to measure the direct path sound (red line) and the reflected path of sound (black lines) and then use the difference in your half wave calculation. Correct?


Thanks.


Larry


----------



## Terry Montlick

Exactly, Larry, where the angles hitting the wall are equal.


----------



## Ethan Winer

Scott,


> I was planning on entire front and 42" of side all the way around.


----------



## Ethan Winer

Jason,


> what % of sq/ft needs to be covered with (1") acoutic treatment to achieve correct RT60?


----------



## Drew Eckhardt




> Quote:
> _Originally posted by Terry Montlick_
> *
> 
> The idea with the crossover frequency and SBIR is to arrange sub and main speaker so that neither generates an audible 1/4 wavelength frequency. Just a simple calculation based on speaker distance to the wall is necessary.
> 
> 
> Take the distance of the speaker or subwoofer to the wall in feet, and divide 282.5 by this distance. (282.5 = 1130 feet/sec, the speed of sound at room temperature, * 1/4 wavelength). The result is the frequency in Hz that would generate 1/4 wave cancellation.
> *



What do you do with a dipole main that has its null aimed aproximately at the side wall?


----------



## kromkamp

Thanks Terry. To sum up, the first reflection points need to be treated for two reasons:


1)For high frequencies, you get a time domain reflection that can be seen in the impulse response


2)For low frequencies, you get boundary interference at a certain frequency causing cancellations to occur.


Ethan has great plans for a high-bass membrane trap that is centered precisely where I need it (150-300Hz).


----------



## Terry Montlick




> Quote:
> _Originally posted by Drew Eckhardt_
> *What do you do with a dipole main that has its null aimed aproximately at the side wall?*



You don't have to worry much about dipole mains and side wall SBIR. Unlike a

monopole, a dipole doesn't become a uniform spherical radiator at low frequencies.


----------



## Terry Montlick




> Quote:
> _Originally posted by kromkamp_
> *Thanks Terry. To sum up, the first reflection points need to be treated for two reasons:
> 
> 
> 1)For high frequencies, you get a time domain reflection that can be seen in the impulse response
> 
> 
> 2)For low frequencies, you get boundary interference at a certain frequency causing cancellations to occur.
> *



Yup. And they are both dependent on distance from the wall, or more correctly, path difference to your ears, as in Larry's diagram. This path difference determines:


1. For high frequencies, the time at which an early reflection can occur. If this time is greater than 15 milliseconds or so, it does not get merged by the brain into a single spatially-shifted sound image, and you don't have to worry about it screwing up your front sound stage.


2. For low frequencies, the frequency at which SBIR phase cancellation can occur.


- Terry


----------



## GetGray




> Quote:
> _Originally posted by Ethan Winer_
> *Scott,
> 
> 
> > I was planning on entire front and 42" of side all the way around.*


----------



## jasplat88




> Quote:
> --------------------------------------------------------------------------------
> 
> Originally posted by Ethan Winer
> 
> Jason,
> 
> 
> > what % of sq/ft needs to be covered with (1") acoutic treatment to achieve correct RT60?


----------



## SanchezGZ

I am kind of in the same boat as jasplat88, in regards to proper setup to determine accurate measurements because I have NHT T6's and a W1 sub to recreate bass...


----------



## Dennis Erskine

The position of a sub in the room will affect the level of excitement of the room's modes. For example, if you have a peak at the seating position, placing the sub in a null for that frequency will eliminate the peaks for that mode. Having said that, placing two or three subs in the room will create a "virtual" sub at some altogether different location in the space. In other words, the three subs together will behave as though there was a single sub in some other location.


Yes, setting up a room with multiple subs is more difficult than with a single sub...although significant benefit can be gained with this method. HOWEVER, you have a difficult problem. You cannot move two of your subwoofers. To do so would place your sound stage at risk. The best you can do is move the single sub around to optimize (favorably) your bass response at the listening position(s). That may leave the sub in the middle of the floor somewhere. Next, using parametric equalization, you tame the remaining peaks at the listening position. You are now left with nulls. These nulls can be addressed with specific band frequency absorption.


Using full range speakers in a small room (residential sized, for example) will simply mean that if you don't like the sound, move 6" and it'll change.


----------



## jasplat88

Dennis....thank you for the response. That helps---kind of







You are right about my two front subs and the fact that they are pretty much set. I do have the option with my mains (L/R) since they are side firing to have the subs fire inside the room or towards the side walls. I have already tested both of these positions and found better bass for the rear seats by having them fire at the side walls. The front seating location bass did not improve much if any by this change--although I think it got a little more boomy in the higher bass freq's when the subs were firing towards the center of the room.


I have not moved my dedicated sub down there yet, but will do that this weekend. I will also graph my bass response once all subs are down there. After our earlier discussion about the front wall treatment with my particular speakers I have decided to continue testing different acoustic treatments for the highs and mids (1" 703 equilivant), but am more concerned about the bass at this point.


I did not mention, but I am limited on where I can place the sub IF I choose to place it in the rear of the HT. Otherwise, I can put it up front as well, but want to try the rear location first (and possibily settle for a acceptable vs. preferred) bass response curve---aesthetics reasons. I will try to chart out some response curves tomorrow and post them.


-Jason


----------



## kromkamp

Terry,


Just out of curiousity, does SBIR repeat across multiples of the fundamental? (ie. If I get cancellation at 220, will I also get it at 440,660,880 etc)


Andy K.


----------



## marjen

I am trying to find either 703, insulshield or comperable product somewhere in CT. I have spend the last hour calling around and NO one seems to cary anything. Help!! I am redoing the front of my theater and really want to do it right. Any suggestions.


----------



## Brucemck2

Great thread!


Early on someone asked about perf screeens ...


I'm treating screen wall with 4" 703 mounted 4" off the wall.


Would a perforated screen (mounted approx 4" in front of the 703) improve overall sound quality? Seems like it should, as it eliminates a largely reflective surface over a large fraction of the front wall.


On the other hand, my inuition vis-a-vis acoustics is often confounded by physics.


ps -- if answer is "it depends": room is 18' by 15' by 12'; first reflections off the side walls are being handled by 2" RPG binary diffusor panels or 7" skylines (will decide by ear); rear wall ceiling has soffit with bass trapping.


----------



## Terry Montlick




> Quote:
> _Originally posted by kromkamp_
> *Terry,
> 
> 
> Just out of curiousity, does SBIR repeat across multiples of the fundamental? (ie. If I get cancellation at 220, will I also get it at 440,660,880 etc)
> 
> 
> Andy K.*



Yes, it does. However the higher frequency nulls are generally not a problem. They get lost in the increasingly large number of room modes which form the reverberant sound field.


- Terry


----------



## kromkamp

Thanks, thats what I thought. If I take a linear plot of my room with ETF, I do see these multiples of the fundamental. However, on the logarithmic graph the multiples are not an issue (you can see a dip at 440 but its small)


----------



## Dennis Erskine




> Quote:
> I have already tested both of these positions and found better bass for the rear seats by having them fire at the side walls.



This actually has little to do with the low frequency performance of the room...or impacts on modal response. We aim the drivers away from the audience and place a 1" acoustic (fiberglass) panel on the wall the driver points to. The problem is the mechanical noises of the sub, and the slap of the driver against the air creates an artifact of the sub's motion. That artifact can be (a) distracting and (b) fool you into thinking you can localize sounds below 80Hz.


----------



## LarryChanin




> Quote:
> _Originally posted by Dennis Erskine_
> *
> 
> Yes, setting up a room with multiple subs is more difficult than with a single sub...although significant benefit can be gained with this method. HOWEVER, you have a difficult problem. You cannot move two of your subwoofers. To do so would place your sound stage at risk. The best you can do is move the single sub around to optimize (favorably) your bass response at the listening position(s).*



Hi Dennis,


I was hoping you could help me with a theory question.


If I understand Jason's situation correctly two of his subwoofers, which are integral to his mains, are on the right and left main channels. His third sub is a dedicated LFE subwoofer.


In the white papers I've read about using multiple subwoofer to smooth bass response I was under the impression all the subs were operating on the same signal.


My guestion is even if Jason could reposition his mains without adversely affecting their sound stage, wouldn't the fact that his three subs are on three different channels mean there would be little or no effect on smoothing bass?


In other words for purposes of discussion suppose his mains were comprised of a right and left satellite and a right and left subwoofer (with suitable crossovers so the subwoofers integrated well with the satellites). In this example the three subs could be repositioned independently without adversely effecting the sound stage of the satellites. However, would it be reasonable to expect to see improvement in the bass response if the subs were operating independently on three different channels?


If we ran test sweeps on the above configuration in an attempt to test this no doubt we could come up with an arrangement that would appear to smooth the bass response. That might be due to the fact that during testing the same signals are being delivered to all speakers. However, in normal operation when the subs were on different channels would the smoothing effects of opposing subs disappear?


Thanks.


Larry


----------



## jasplat88

Here's a quick follow-up on my room and sub situation. I moved down my dedicated sub which I have running through the BFD. The mains (with subs) are still run only feeding full channel to each main (no LFE feed). I placed my rear sub where I would *like* it to be and graphed the response curve. I then used the BFD to adjust for the TOTAL room peaks (i.e. I did NOTHING to change the bass response feed or produced by the front main speakers).


Prior to the BFD, the room was pretty boomy. After the BFD adjustments the bass response is significantly better. A lot of the boominess is gone and I am able to crank deep bass songs and notes much louder without the ringing.


HOWEVER, is it possible, I (and potentially others) *like*


----------



## Terry Montlick




> Quote:
> _Originally posted by jasplat88_
> *
> 
> Dennis/Terry/Ethan, I know we have talked about adjusting the response curve, but have you noticed in your experience that some people actually prefer a response curve that is not flat?*



Yes. For example, the characteristic Bose sound has boomy bass, and some people love it.


It is ultimately a matter of personal preference. However to me, the original meaning of "high fidelity" is something to consider. Audio equipment has improved over the years so as to be capable of much more accurate response -- that is, fidelity to the original sound recording.


But we are currently experience a boom in bass (sorry!







) due to unprecedented ease in reproducing very low frequencies. In the older days of hi-fi, you struggled to get much of any very low bass any way you could. You put speakers right in the corners to get the most room mode boost, regardless of uneven frequency response.


So IMHO, the emphasis on huge bass is in some sense a current fashion. Also, something very important to consider is that psychologically, we vertebrates perform accommodation to sensory stimuli. Without both high and low levels of any stimulus, we tend to just tune it out because it becomes the norm.


A good movie sound mix will make judicious use of loud bass, so that when it is important dramatically, you really hear it, and the movie becomes that much more exciting. The bass should really be there when it is needed, hence the need for power and accuracy in subwoofer response. But to have it cranked up all the time is not necessarily desirable.


Regards,

Terry


----------



## Dennis Erskine

The fact that each sub is playing something different is no really relevant to smooth bass reponse. Each sub is still producing frequencies which excite room modes. Now, having said that, if each of three subs is playing something different, you cannot use mutual placement as a means to smooth response between them. Full range speakers are a real problem in small rooms...everyone in the room will hear something different whether discrete bass channels are used or not. The non-directionality of bass makes it rather moot do to this in any case.

---

Your mains and your subs typically have a path difference between the drive and the listening position. At the crossover point (usually 80Hz) the sub and the main speaker are playing exactly the same sound. At the crossover you want the sub to be in phase with the main with respect to the listening position. If you don't, you'll have a peak or null at the crossover point. The phase knob allows you to adjust the phase of the sub to match the mains at the listening position. In your case, they must be in phase at 55Hz.

----

It is true that most do not prefer flat frequency response. We prefer a roll off in the high frequencies and, today, there's a lust for boom. You might do a search on "X Curve" for some background on this area of psychoacoustics.

http://www.screensound.gov.au/glossa...e?OpenDocument


----------



## BobL

It does come down to preference. Also, most peoples' reference material (music or otherwise) is probably boomy. Currently, fashionable as Terry states







Many people listen to music in cars or in areas which aren't close to being accurate. And many people have not heard a reference system. So, when one listens to something in a room with a relatively flat frequency response they will wonder. Where's the bass?


I agree with Terry that you will hear the bass if it was meant to be there. Another consideration is how boosting the bass affects the rest of the frequency spectrum. If you are having a conversation in a quiet room and each person is talking at the same volume level say 75db it is pretty easy to understand them. Now, would you be able to understand them if you were sitting in a Dodge Viper zipping down the road or just at idle for that matter without raiding the volume of your voices. That low frequency rumble is interfering with the intelligibility of your dialogue. The same thing happens when you boost a frequency range. You have raised the overall SPL of the room and this can make dialogue intelligibility and detail tougher to discern.


Now whether you'd rather be in the Viper or able to hear the conversation is your choice. OK, maybe a bad analogy! But, you get the point.


Bob



Bob


----------



## jasplat88

Terry/Dennis/Bob...thanks for the responses. I think in my personal experience (as a DJ for serveral years) I was suckered into the "pump up the bass" mentality where you help entertain your audience by helping them *feel* the music. Since that time (that was about 12 years ago) I have become accustomed to bass (although I have never owned a car where you could "feel" the bass a car or two away....but I have always had sub in my cars and in my home system. I think I (and at least many of my friends) prefer some boom


----------



## Newk2

I am installing rigid fiberglass on the screen wall of my family room/HT (plus 2' back on the sidewalls from floor to ceiling). For each of the 2 front wall/wall corners I have 2'X5'X4" rigid fiberglass to span the corners and act as base traps. How high off the floor should the bottom edge of the 'traps' be?


Continuing from the trap up to the ceiling, is spanning the corner with the 1" rigid fiberglass for mid/high absorption ok or should it be placed flat on the walls? I save a little material by spanning and I think I am cutting it close as it is. If I span with the 1", should I leave a gap between it and the trap?


----------



## LarryChanin




> Quote:
> _Originally posted by Dennis Erskine_
> *The fact that each sub is playing something different is no really relevant to smooth bass reponse. Each sub is still producing frequencies which excite room modes. Now, having said that, if each of three subs is playing something different, you cannot use mutual placement as a means to smooth response between them. Full range speakers are a real problem in small rooms...everyone in the room will hear something different whether discrete bass channels are used or not. The non-directionality of bass makes it rather moot do to this in any case.
> *



Hi Dennis,


Thanks very much for the response.


Aside from perhaps wasting money, is the simple solution to someone who has full range speakers to merely set them to small and set the crossovers sufficiently high?


Thanks.


Larry


----------



## LarryChanin




> Quote:
> _Originally posted by jasplat88_
> *
> 
> Can someone please provide some guidelines on what RT60 should be in:
> 
> 
> 1) A home theater enviroment?
> 
> 2) A music enviroment?
> 
> *



Hi Jeff,


Try this thread for a start.

RT60 what is a good value! 


If you are refering to two-Channel music then there should be different Reverberation Times. However, I believe that multi-channel music can happily coexist in a room whose acoustics were designed for multi-channel movies.


Larry


----------



## Ethan Winer

Scott,


> if the poster was correct on cost of good tiles (about $2000 for my room tiles only). 
The FAQ directs that the corners are the best spots for the traps.


----------



## Ethan Winer

Jason,


> When I take test measurements and attempt to identify where and how much bass traping I need


----------



## BobL

You are probably better off setting your mains to small and connecting your subs to the LFE output from your BFD. Then I would try to find the best location for your subs and seating if that is a possibility. Before we work with three subs, let's start with one.


1. Put your sub in the corner and move your mic between the corners of the room and take a reading of Pink noise on the LFE channel only. Theoretically, that same corner should be fine. But, I like to double check especially if it is not rectangular. This should show all your room modes.


2. Now move your seating to get the smoothest response possible.


3. Place sub in your seating location and move the mic around the room and find the areas that give the smoothest response. This will be somewhere into the room. Not along the walls.


4. Next place your subs so that if you draw a line from each sub. That line would intersect one of your ideal sub loacations. This is probably a good starting point for your sub placement. Start moving each one individually now and find the best spot. This is the virtual sub technique. Note: if your fronts and seatings is fixed. I'd probably just use this technique first and just take measuments each time you move your third sub and find the best spot this way.


5. EQ out whatever peaks you have left.


Also, when doing this you might want to play with your crossover point a bit. Since the placement affects this. Changing your crossover might yield a smoother response as well. 80 works for the majority of small rooms but sometimes you can fix various problems by altering the crossover point.


About RT-60. Dennis gave great recommendations in the other thread referenced. But, remember RT-60 measures overall room reverberation. You can have a good RT-60 and still poor sound becuase you didn't treat the first reflections. So just having enough absortion to achieve a good RT-60 will not necessarily bring good sound. The absorptions has to be placed in the correct areas.


Larry,


Search Dennis' name. He had a relatively recent thread about why setting your speakers to small and using subs to correct for SBIR effect is useful. The answer to your question is probably yes. Again depends on placement and how the best placement for low frequency information isn't the best placement for the mids and highs.


Bob


----------



## Ethan Winer

Bob,


Just a little nitpicking:


> That low frequency rumble is interfering with the intelligibility of your dialogue.


----------



## Terry Montlick




> Quote:
> _Originally posted by Ethan Winer_
> *ou already got good advice on sub placement, but I'll add that bass traps do more than flatten the low frequency response. Just as important is the way they reduce ringing, and in a way that EQ cannot.
> *



I thought we'd been over this already, Ethan.










Remember when we were discussing the cancellation of room modes by EQ, and though you didn't intuitively understand it (quite reasonable, since it's not intuitively obvious), your engineer friend explained to you that there was such a thing as an "inverse filter" for a linear system? That such a filter could fix resonance in both the frequency and time domains simultaneously, and that the order of signal processing in a linear system doesn't matter?


Or maybe you are referring to something else by the term "ringing."


Regards,

Terry


----------



## BasementBob

LarryChanin/jasplat88:


> Quote:
> Can someone please provide some guidelines on what RT60 should be in: 1) A home theater enviroment?



Another good thread, other than the one Larry provided, IMHO, is:
http://www.avsforum.com/avs-vb/showt...60#post4011194 

where RT60 based on room volume is used. (A control room is not like a music environment room.)


----------



## tonybradley

I read the first couple pages and was hoping someone could carify something that Dennis stated on the first page.


His Statement:


*"Now A.


Requirements for multi-channel (more than 2) are different than that required for 2 channel.


In multi-channel, the entire wall behind the front speakers is treated. You want none of the back reflections to overlay the surround field or the bring the reverberent field forward (your reverberent field and surround field is created by the multi-channel processor or mix, not so much the room as is mandatory for 2-channel). Depending on speaker placement, this treatment is brought forward along the side walls. Wall treatments are floor to slightly above ear level (where exactly is also a function of front speaker heights). While one could argue the sound at their feet is of no concern, often that square footage of treatment is required to bring the room's RT60 down to the lower levels required for multi-channel playback.


If you have soffits, the bottom of the soffits is also treated...several reasons, right tricorners among them.*



The statment that says "Wall Treatments are floor to slightly above ear level...". I plan not to use Linacoustic, but treat my room with Bass Traps and Absorption panels at the First Order Reflection Points.


Question 1. Should my Sound Absorption panel only be from the floor to above the ear, or should it extend the height of the wall?


Question 2. After reading the first few posts, I see that the front wall should be treated. I have checked my area for Linacoustic or Insulshield and cannot find it. So, if I was NOT to put drywall on my front wall, but instead, stuff R19 between the studs, and cover it with GOM....would that be an effective way to treat the front of the room?


----------



## jasplat88

Bob/Dennis/Terry/Ethan,


Here's a follow-up on our earlier discussion. I re-measured my room---this time with ONLY the dedicated sub, and I moved the sub from the rear of the room to the front. I ran one measurement set with the sub set about 1/3 the width of the room (attached blue line), and another with it very close to the center of the width of the room (pink like). I think both of these results are worse than what I had running all three when the dedicated was in the rear of the room. It's possible that the main L/R subs (full range) were helping mask that nasty null at 56Hz I guess. Is it strange the null did not move when moving the sub (just reduced the null---but added another null at 125? Should I keep moving it around the front stage and measuring? Should I avoid the front corners?


Pink noise generated no more than 2dB difference between the front left center and right corners. The rear corners also read within 2dB....so basically all the corners showed very similar dB levels (sub placed in the center of the front wall). Is that suppose to tell me anything? I have not tried putting the sub in my listening position. If I do that how do I tell if the bass is smoother (without measuring)? If measuring is envolved, that's ok, but just a PITA to do it in potentially dozens of spots around the room.


-Jason


Edit: It's helpful if I attach the chart huh?


----------



## BobL

Hi Ethan,


I agree it might not be the best analogy and I wasn't factoring the road noise/ wind noise for the analogy. Not to mention if I was driving the Viper I wouldn't care as much about conversation







Masking is a bigger problem! A good analogy for that would be to trying to understand somebody in a crowded restaurant with everybody having conversations.


I was just pointing out that if you had the bass frequencies playing at 120db and dialogue at 70db the dialogue would be more difficult to understand than if the bass was at 70db. And that overly exaggerating the bass region or any region can affect the overall quality of the sound.


Bob


----------



## Terry Montlick




> Quote:
> _Originally posted by jasplat88_
> *It's possible that the main L/R subs (full range) were helping mask that nasty null at 56Hz I guess. Is it strange the null did not move when moving the sub (just reduced the null---but added another null at 125? Should I keep moving it around the front stage and measuring? Should I avoid the front corners?
> *



Good chart, Jason. There should be some sub position which doesn't fall in that 56 Hz null for your listening area. Of course, that position may have its own problems. What are your room dimensions and where are you putting the measurement mic?


As for the dip at around 125 Hz, why worry about it? It will be well above your crossover frequency.


Regards,

Terry


----------



## jasplat88

Terry,


My room is 11'2" x 23'6" x 7'2" (the 7'2" is an average of ceiling heights that range from 7'6" to 6'6"


----------



## marjen

A treatment question for all of you. Is there anything other than rigid fiberglass that will work for the front wall? How about those rigid insulation panels at the lumber yards? Rigid fiberglass is proving to be VERY difficult to track down.


----------



## jasplat88

Mark,


Have you tried your local HVAC dealers and ask for ductboard or ductliner...it has VERY similar properties as 703 and Linacoustic and is MUCH easier to find. I was able to get 2 boxs (10 2'x4' sheets per box) for $65. Works great!


-Jason


----------



## marjen

NO I haven't Jason, what does it look like? Is it rigid our a role? I will ask, but I did call two plumbing/heating places asking for ductboard or rigid fiberglass and they had no idea what i was talking about.


Another questions for everyone. Uf I plan on having curtains in the front to the sides of the screen, bo they negate any effects of using GOM and rigid fiberglass in the first place on the front wall?


----------



## jasplat88

Mark,


It is rigid and they use it to line ducts. Here's a pic of what mine looks like on the wall before covering.


-Jason


----------



## ChrisWiggles

See here:

http://www.ethanwiner.com/acoustics....d%20fiberglass 


Any competent commercial insulation/heating company or supplier should know what this is. Small home-type installers may not.


----------



## BasementBob

marjen:


You can use anything found on this page:
http://www.bobgolds.com/AbsorptionCoefficients.htm 

(fiberglass, rockwool, cotton, polyester, even open cell foam)


----------



## Newk2




> Quote:
> _Originally posted by Newk2_
> *I am installing rigid fiberglass on the screen wall of my family room/HT (plus 2' back on the sidewalls from floor to ceiling). For each of the 2 front wall/wall corners I have 2'X5'X4" rigid fiberglass to span the corners and act as base traps. How high off the floor should the bottom edge of the 'traps' be?
> 
> 
> Continuing from the trap up to the ceiling, is spanning the corner with the 1" rigid fiberglass for mid/high absorption ok or should it be placed flat on the walls? I save a little material by spanning and I think I am cutting it close as it is. If I span with the 1", should I leave a gap between it and the trap?*



Is my question not detailed enough or just stupid?


----------



## ChrisWiggles




> Quote:
> How high off the floor should the bottom edge of the 'traps' be?



Shouldn't really matter at all. Obviously resting the panels on the ground with gravity is easier than suspending them in the air, but there's no performance difference or nuthin.



> Quote:
> If I span with the 1", should I leave a gap between it and the trap?



Maybe I'm confused, but it sounds like you are using thicker panel across the corner for your trap right? And thin fiberboard elsewhere on the walls? All spanning the corner does is help get more of the bass, and the thicker the better (for ANY panel, including on the walls). Continuing a corner-spanned trap up to the ceiling makes for a neat corner of course, ideally you'd want the whole thing with thicker paneling there, but if you're running low there's no "problem" with using a thinner amount on the upper part of your corner span.


----------



## Newk2

Chris,


Thank you. I was starting to feel like a pariah. I posted long ago in the Home Theater Builder Forum with no response.


When I purchased the Certainteed 4'X10'X2" ductboard I kind of freaked at the price. I decided, after seeing that Ethans traps were only 4' long, that 5' ones would work and quarterd the sheet to make (2) 4" thick.


Realizing now what a relatively small amount of money that was, I would go ahead and buy 2 sheets to do both corners the full 9' 6". But alas, I live in Bremerton and the business I deal with is in Renton. It is only open during regular business hours. It ends up being an almost all day venture and a hard way to justify a day's use of leave.


I will run my curtain diagonally across the corner to conform to the spanning of the trap so thought that if there was no problem I would span the corner the same with the 1" material from the top of the trap to the ceiling.


I remember reading somewhere that someone recommended leaving a space at the bottom of the trap. I did not know if the space was necessary, but if so, how much?


Again, thanks. After your post, I'm feeling a little more secure and a little less sensitive...







... possibly a little silly as well.


----------



## Terry Montlick




> Quote:
> _Originally posted by jasplat88_
> *
> 
> My room is 11'2" x 23'6" x 7'2" (the 7'2" is an average of ceiling heights that range from 7'6" to 6'6"*


----------



## dynamowhum

Please explain the term right tricorner. Is this were a soffit meets the corner formed by the walls or is it the staggered corner formed by both the soffit facial and walls?

Along these same thoughts is it best to make a trayed ceiling into an octagon rather than a rectangle?


----------



## marjen

Thanks you so much guys for the list of alternatives and additional info on the duct board, etc. Looks like I have some phone calls to make.


----------



## bpape

Tri-corner describes where 2 walls and the floor or 2 walls and the ceiling meet (or any other 3 surfaces for that matter). If you can point to a position and have it be the end of 3 different dimensions, it's a tri-corner.


That's why that place is particularly effective for treatments. It is at the end of 3 different dimensions and therefore has the opportunity for maximal absorbtion of all frequencies AND modes from all 3 dimensions.


----------



## Ethan Winer

Terry,


> your engineer friend explained to you that there was such a thing as an "inverse filter" for a linear system? That such a filter could fix resonance in both the frequency and time domains


----------



## Terry Montlick

Ethan,


Bill is right on both points, however for low frequency room modes, the theory works quite well in practice.


For point 1, inversion of the low frequency room modal response can be done with extremely simple EQ. This works because low frequency room modes are (for all practical purposes) minimum phase. All you need is another minimum phase filter to cancel them. Any parametric equalizer provides such filters - they are simple 2nd order sections, with symmetrical pairs of poles and zeros. So for low frequency mode cancellation, the fanciest DSP offers no advantage over a simple analog filter.


As for point 2, the space that the filter is effective over is proportional to the wavelength of the room mode. So here again low frequencies make it practical. EQ for can cover not just a very precise position (such that you have to keep your head in a Mayfield clamp), but a reasonable listening area.


I too am skeptical of practical inverse filtering for high frequencies, at least for the near future. Current research has not show a whole lot of progress. The preciseness of head positioning is indeed a problem in this case. Particularly troublesome are the nasty artifacts which are audible BEFORE the main portion of a sound is heard.


Regards,

Terry


----------



## jasplat88




> Quote:
> _Originally posted by Terry Montlick_
> *Hmm, there is no obvious modal source for that deep 56 Hz null, given the info you provided. The mic position is kind of close to the rear wall, and I suspect SBIR. It's hard to diagnose exactly, because an n'th octave frequency response is typically a composite of multiple FFTs with their own time windows. It's pretty "processed", and one doesn't know the details of the short-term vs. long-term analysis characteristics -- how much SBIR vs. modal response is represented in the display. If the distance to the back wall is more like 5', a 1/4 wave null at 56 Hz can occur.
> 
> - Terry*



Terry, thanks for the post. I thought 4'6" off a back wall in a 23'6" deep room was actually pretty far away from the back wall....no? I measured this morning and it is entirely possible that the mic location has been closer to 4'10" (maybe even 5') off the back wall. So you are saying if I move the mic back....say to 4' or even 3'6" (i.e closer to the back wall) and the null moves up in frequency, then the null is casued by SBIR? I will try taking some measurements at and around my previous null location and report back.


-Jason


----------



## jasplat88

Bob has been helping me behind the scenes, and here is part of one of his pms:


[qoute]Anyway, you have room modes at:


Length

24, 48, 72 hz


Width

51, 102 hz


Height

79 hz Basically don't have your ear height at about 1/2 this dimension, this would create a null around 80hz. Not a good spot for a nulll with the crossover at 80hz.


Now as I said real world measurments are not as perfect as calculated. Now using your seating measurement you have basically placed yourself in a null at 48 and 51 Hz. Which between the 1/6 octave measurment and real world fudge factor I bet is the 56hz on your graph. You have a double whammy there causing that nice dip.


Move your seat forward (only the mic for now) 1.5 feet and move the sub about 62" from the side wall and then move it 44" into the room. Now take your measurements." [/quote]


Well Bob, I did as you suggested and moved my main (only using dedicated sub for these tests) sub 66" from the side walls (BTW this places it almost dead center in the middle of my stage, and then moved it ~44" out from the front wall (I will attach a pic in a minute so you can see physically where it is). Since I wasn't sure if the 44" was to the front of the sub, or driver or middle of sub enclosure, I placed it ~44" to where the magnet on the driver probably is. The front of the sub is 48" to the wall and the middle of the enclosure is 40" if that helps any.


Well the response curve (green) is much better and the 56Hz null is much improved and there is a slight dip now at 50Hz. Overall though this is better. Now the problem is....the sub can't stay there (see next pic...it's exactly where the center channel will go), and the listening position is fixed at slightly 1' back from where I moved the mic (the mic in this measurement was 6' from the back wall, and 3' from the side wall). But I think we are just trying to determine the IDEAL sub location and understand my room modes. Based on Bob's curve (green one) I should be able to flatten out at about 80dB from 25Hz-111Hz using the BFD no?


I have been measuring from what will be my music listening postion (rear row), however, my main movie watching location will be on the front row and I have not taken any measurements there....should I?


-Jason


----------



## jasplat88

Here's a follow-up pic to show where the sub is located in the latest measurements I took (green line from previous post).


----------



## ChrisWiggles

Newk: you must be in the navy then? I see how that would be a little difficult to make it all the way to renton. You might be getting your stuff at the same place I got my fiberboard, i forget the place's name, like JR or something i forget.


In any case, I don't know of any reason for gaps for your trap. The only thing I could think of was maybe airflow to behind the trap so it doesn't get stale, but it's not like people are breathing behind the trap in your corner, and the thing is porous, so...


----------



## HT-DJ




> Quote:
> _Originally posted by jasplat88_
> *Here's a follow-up pic to show where the sub is located in the latest measurements I took (green line from previous post).*




I'm wondering if that "extra" insulation that's leaning against the walls in this pic has been there all along for all the measurements you taken so far? I think that could effect your results. Best to either put it where it belongs, or take it out of the room, I think.


----------



## HT-DJ




> Quote:
> _Originally posted by Terry Montlick_
> *
> 
> For point 1, inversion of the low frequency room modal response can be done with extremely simple EQ. This works because low frequency room modes are (for all practical purposes) minimum phase. All you need is another minimum phase filter to cancel them. Any parametric equalizer provides such filters - they are simple 2nd order sections, with symmetrical pairs of poles and zeros. So for low frequency mode cancellation, the fanciest DSP offers no advantage over a simple analog filter.
> *




Terry,


I appreciate all your posts, but would it be possible for you to explain the above paragraph in layman's terms? I'm trying to digest all of this information, and do not understand what you wrote.


Thank you.


----------



## jasplat88




> Quote:
> _Originally posted by HT-DJ_
> *I'm wondering if that "extra" insulation that's leaning against the walls in this pic has been there all along for all the measurements you taken so far? I think that could effect your results. Best to either put it where it belongs, or take it out of the room, I think.*



It has not moved during any of these tests, but it should have little to NO impact on the frequencies I am measuring (bass). It is there as I am thinking I will need to add more acoustic panels (and that is where they would go or at least where I would like them to go) to drop my RT60 when I get to that phase. I did remove all the panels I had along the front wall prior to any measurements (i.e. my front wall is reflective and not treated with anything at the moment). Good observation










-Jason


----------



## Dennis Erskine

A right tricorner is a reflector as well (that's how bicycle reflectors are made)...it has the characteristic of reflecting something (light, HF sound) back at the same angle it originated from.


----------



## Newk2

Chris,


Not in the Navy but work for the Navy as a civil servant. The place I purchased my ductboard from is actually in Kent and the business name is Paragon Pacific. They sell to individuals but are really set up to sell in large quantities to contractors etc. It is kind of a pain to get one or two sheets (mostly for the warehouse guys). They are friendly and helpfull though. One sheet of 2"X4'X10' rigid liner board with tough guard on the face was about $93 with tax. If I thought there would be much improvement by going all the way to the ceiling, I might go back and buy another sheet on Jan 6 because I will be taking that day off with leave I must take or lose.


----------



## Terry Montlick




> Quote:
> _Originally posted by HT-DJ_
> *Terry,
> 
> 
> I appreciate all your posts, but would it be possible for you to explain the above paragraph in layman's terms? I'm trying to digest all of this information, and do not understand what you wrote.
> *



That's a tall order, but I'll try.


A minimum phase filter is one which alters the phase delay of a signal through it down to its theoretical minimum. There are implications for stability of the filter (its response is guaranteed to be stable and not blow up over time) as well as causality (no sound through the filter can create an earlier effect in time, which is, believe it or not, not true for every possible filter).


Every linear filter (one for which 2X the input produces 2X the output) can be decomposed into two different filters: a minimum phase filter and what's termed an all-pass filter. The latter introduces a delay across all frequencies. One example of a process which cannot be modeled without an all-pass filter is slap-echo, or any other discrete echo.


But the cool thing about minimum phase filters is that any particular one always has an inverse filter, which is also minimum phase. This means that you can cascade a minimum phase filter with its inverse (in either order), and completely undo the filtering process.


So what has all this got to do with room modes? Simply that the resonance of a single room mode, the back and forth wall reflection and amplification at a particular frequency, is minimum phase. So that means it can be completely canceled by its inverse filter. You can readily make such an inverse filter using an off-the-shelf parametric equalizer. You just dial in the frequency, bandwidth, and gain which reverses the effect of the room mode, and you have zapped it. And it doesn't matter that the inverse filter of the EQ came BEFORE the room resonance. The minimum phase principle doesn't care about what comes before what.


Hope this helps,

Terry


----------



## Jeff Hovis

Guys, I have a bit of a situation in my new room. Tonight, I finished hanging all the rigid fiberglass. I'm using CertainTeed UltraGold Duct Board. My room is 26'L x 14'W 9'H (in center). There are two soffits on each side of the room. They extend 2ft into the room and down 1ft. I have covered the entire front wall from floor to ceiling. I have also extended the floor to ceiling treatment out three feet on each side wall. The rest of the room is covered from floor up to 4ft. I clapped my hands and was horrified to hear that awful concrete echo. My room has three exterior/underground walls that are concrete (front, left and right). The right concrete wall is separated by an airspace (alley) that is 26" wide and then a 2x6 wall with drywall that forms the HT interior wall. The left wall has a much smaller airspace of about 2" and is framed with 2x4. The front wall is also similar to the left. The rear wall is an interior wall and has a room on the other side. It is framed with 2x6 studs. ALL walls have R19 batts and one layer of drywall (damn!). The ceiling also has insulation. Could this echo be caused by the soffit?


My fiberboard properties can be seen here:
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Terry Montlick




> Quote:
> _Originally posted by BasementBob_
> *jasplat88:
> 
> There's no axial mode for that room near 56hz, but there is a tangental mode at 55.8hz (1,1,0).*



Yes, but a center front subwoofer position cannot excite this mode. Yet there was a significant null in the corresponding frequency response.


----------



## BasementBob

jasplat88:


> Quote:
> My room is 11'2" x 23'6" x 7'2" ... Hmm, there is no obvious modal source for that deep 56 Hz null



There's no axial mode for that room near 56hz, but there is a tangental mode at 55.8hz (1,1,0).


First few modes (axial, tangental and oblique): 24, 47.3, 50.4, 55.8, 69.6, 71.3, 78.6, 82.2, 87.8, 92, 93.4, 95.9, 96.4, 100.9, 103.7, 105.0, 106.5, 108.3, 111.7


----------



## Jeff Hovis

OK, I went back and read a little about right tri-corners. I think I definitely need to treat the bottom of my soffits. On the other hand, it's quite different if I clap or whistle while seated in my chair...there is virtually no echo. I guess that's why you treat up to ear level while seated. Maybe, I'll only treat the soffit area in front of the seating area.



> Quote:
> _Originally posted by Jeff Hovis_
> *Guys, I have a bit of a situation in my new room. Tonight, I finished hanging all the rigid fiberglass. I'm using CertainTeed UltraGold Duct Board. My room is 26'L x 14'W 9'H (in center). There are two soffits on each side of the room. They extend 2ft into the room and down 1ft. I have covered the entire front wall from floor to ceiling. I have also extended the floor to ceiling treatment out three feet on each side wall. The rest of the room is covered from floor up to 4ft. I clapped my hands and was horrified to hear that awful concrete echo. My room has three exterior/underground walls that are concrete (front, left and right). The right concrete wall is separated by an airspace (alley) that is 26" wide and then a 2x6 wall with drywall that forms the HT interior wall. The left wall has a much smaller airspace of about 2" and is framed with 2x4. The front wall is also similar to the left. The rear wall is an interior wall and has a room on the other side. It is framed with 2x6 studs. ALL walls have R19 batts and one layer of drywall (damn!). The ceiling also has insulation. Could this echo be caused by the soffit?
> 
> 
> My fiberboard properties can be seen here:
> http://www.bobgolds.com/AbsorptionCoefficients.htm *


----------



## BasementBob

jasplat88:

If you get bored and find yourself with nothing to do, what happens with the subwoofer/mic at these locations:

- subwoofer at (6', 2'6.6", 1') and the microphone at (13'3.1"", 7', 3'8.9")

- subwoofer at (5'11.9, 1'11.9", 1') and the microphone at (12'4.7"", 7', 3'8.9")

( RPG Room Optimizer, 20hz to 80hz)


----------



## jasplat88




> Quote:
> _Originally posted by BasementBob_
> *jasplat88:
> 
> If you get bored and find yourself with nothing to do, what happens with the subwoofer/mic at these locations:
> 
> - subwoofer at (6', 2'6.6", 1') and the microphone at (13'3.1"", 7', 3'8.9")
> 
> - subwoofer at (5'11.9, 1'11.9", 1') and the microphone at (12'4.7"", 7', 3'8.9")
> 
> ( RPG Room Optimizer, 20hz to 80hz)*



Hey Bob,


I will do this. Probably tomorrow (Monday) night and report back. I assume these are locations off the BACK wall correct? Read....for example in your first measurement (6' from the back wall, 2'6.6" from either side wall, 1' off the floor)? Just want to make sure before I get started. Thanks!


-Jason


----------



## BasementBob

jasplat88:

The program assumes a symetrical/rectangular room. So they are measurments off either the back or the front wall, as you prefer. They are all (23'6" dimension, 11'2" dimension, 7'2" dimension). I would have tried them from (front, left, floor), because then the microphone positions seem about right for a chair. I wouldn't swap start points between sub and microphone (i.e. sub measured from _back_ and microphone measured from _front_ -- would be bad).


----------



## ChrisWiggles

Leon:


I paid about 120 bucks for two entire batts of 703-type fiberboard, so that sounds like a very high price...?


----------



## bpape

Jeff,


Did you do the batting on the 'untreated' area or is it still plain drywall?


----------



## Brucemck2

Once again, asking whether it matters or not to room acoustics to use a perforated screen or not -- is the decision solely based on whether there's a speaker behind the screen?


I've treated screen wall with 4" 703 mounted 4" off the wall.


Speakers are out in the room, NOT behind the screen.


Would a perforated screen (mounted approx 4" in front of the 703) improve overall sound quality? Seems like it should, as it eliminates a largely reflective surface over a large fraction of the front wall. On the other hand, seems like most frequencies can find themselves around the screen anyway.


ps -- if answer is "it depends": room is 18' by 15' by 12'; first reflections off the side walls are being handled by 2" RPG binary diffusor panels or 7" skylines (will decide by ear); rear wall ceiling and screen wall corners all have soffits with bass trapping.


----------



## BasementBob

Brucemck2:


If you have a perforated screen, then by definition a lot of sound goes through it virtually without change (well they attenuate high frequencies a bit). If it's not perferated I've always assumed that it reflects highs but lows go right through it, but I've never seen measurements so I can't define 'highs' and 'lows'.

With the exception of first reflections, it makes less (none?) difference where absorbtion goes, as opposed to the absorbtive surface area and thickness (Sabine formula).


If your "Speakers are out in the room, NOT behind the screen", then I wouldn't get a perferated screen. The problem with perferated screens is moire, which is an visual interference pattern between the hole spacing of the perferations and the projector grid pattern. The second problem with perferated screens is you loose 10% of your brightness.


In my case I want a big screen in a short room, so I can't put my center above or below my screen, so it has to be perferated, so all the speakers are going behind it, along with, probably, a bunch of absorbtion.


----------



## Ethan Winer

Terry,


> Bill is right on both points 
inversion of the low frequency room modal response can be done with extremely simple EQ


----------



## Ethan Winer

Jeff,


Your question seemed to have gotten lost among all the chit-chat over phase response and axial modes.










> Could this echo be caused by the soffit?


----------



## Jeff Hovis

bpape and Ethan,

First, I didn't want to add batting to the upper section because from all I've read, it isn't necessary and is only used if one wishes to add fabric to the upper half of the wall. We wanted to do some special paint treatments to the upper half.


As for the echo, it is only bad in a couple of spots. I'm pretty sure it is being caused by the soffit. I'm going to add some additional fiberglass to that area.


----------



## kromkamp

If I were to use a parametric Eq to correct low frequencies (in my case 90Hz for example) on a full-range speaker, does it introduce phase errors across the entire spectrum or only around the center frequencies I am correcting?


Andy K.


----------



## Newk2

Chris,


I am not sure when you bought yours but the price has increased quite a bit since January of this year. How thick was your 703 and how big is a bat? I could have purchased the 1"X10'X4' boards for less than half the price of the 2" ductboard per piece.


----------



## ChrisWiggles

it was 1-inch thick boards, 16 per batt. I paid like 130 for two batts, more than enough for the whole room.


----------



## marjen




> Quote:
> marjen:
> 
> 
> You can use anything found on this page:
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> (fiberglass, rockwool, cotton, polyester, even open cell foam)



So if I understand the info on this page. I could actually just put R-11 or R19 unfaces batts on the front wall, cover it will GOM or something similar and it would have the same effect as using something like 703, JM or other rigid fiberglass?


----------



## jaysoffian




> Quote:
> _Originally posted by marjen_
> *So if I understand the info on this page. I could actually just put R-11 or R19 unfaces batts on the front wall, cover it will GOM or something similar and it would have the same effect as using something like 703, JM or other rigid fiberglass?*



If you look at the absorption coefficients, you'll see that R11 has signifigantly more absorption at some frequencies than 703:


125 250 500 1000 2000 4000 NRC

703: 0.11 0.28 0.68 0.90 0.93 0.96 0.70

R11: 0.34 0.85 1.09 0.97 0.97 1.12 0.95


Now here's the part I'm not sure about, because I was thinking of using R11 as well. The vast majority of my front wall is taken up by the screen. The screen is reflective to certain frequencies (I'm guessing > 500 hz or so...). Since most of the insulation will be behind the screen, does the screen serve to "counter" the extra absorption of the R11. So in practice, perhaps I can use R11 behind the screen, and then save the $$ 703 panels for elsewhere in the room.


But I won't know w/o measuring, and I unfortunately don't have any measuring equipment yet (I'm an all Macintosh/Linux shop at home, still need to build my Windows HTPC and even then, I'd need to invest the mic and whatever else is needed to measure).


j.


----------



## bpape

Having the R11 behind the screen will give you the absorbtion from the lower mids down while the screen will reflect the highs.


You CAN use R11 everywhere IF that is what your room needs and if you have a way to hide it. It doesn't tend to be as easy to make 'visually friendly' as the 703 @ 1".


----------



## Ethan Winer

Andy,


> If I were to use a parametric Eq to correct low frequencies (in my case 90Hz for example) on a full-range speaker, does it introduce phase errors across the entire spectrum or only around the center frequencies I am correcting?


----------



## BasementBob

Ethan:


I thought there were several types of phase shift (time delay > 1ms):

a) equal delay on all speakers, but may be out of sync with the video.

b) different delay between two (or more) speakers -- as you mentioned

c) different delay for different freqeuencies - caused by bad EQ electronics, or bad crossover electronics, or bad bass management electronics, or a bad filter.

d) different delay because some speakers are further away from the listener than others (always happens, think 'two' listeners)

e) multi-driver (single speaker) time delay because if you're head is higher than the speaker then likely the tweeter is closer to you than the woofer

f) subwoofer phase shift control knob (really useful for modally placed subs that are tied to the front left and right channels using high-low filter hardware in the subwoofer), or for a center placed subwoofer.


----------



## dynamowhum

Okay back to tri corners for a moment please. I will have a trayed ceiling in my room so I will have soffit on all walls. Do I treat the corners in the facial area of the soffit as well, they are 11" high? Also is the treatment at 45 degrees on all 3 axies for any tri corner treatment?


----------



## bpape

When you deal with a tri-corner, you are dealing with the intersection of length width and height. Treat the soffit tri-corner as the real one. The other one (depending on how wide the soffit is) is generally pretty far away from the length dimension.


----------



## jasplat88




> Quote:
> _Originally posted by BasementBob_
> *jasplat88:
> 
> If you get bored and find yourself with nothing to do, what happens with the subwoofer/mic at these locations:
> 
> - subwoofer at (6', 2'6.6", 1') and the microphone at (13'3.1"", 7', 3'8.9")
> 
> - subwoofer at (5'11.9, 1'11.9", 1') and the microphone at (12'4.7"", 7', 3'8.9")
> 
> ( RPG Room Optimizer, 20hz to 80hz)*



Ok Bob,


I finally got to it....and wow....pretty impressive. Now what? The sub is off my front stage at both those locations, and the mic height is about a foot higher than where a head will be (although the seating location is almost spot on----from my front row prime viewing seat).


-Jason


----------



## Terry Montlick




> Quote:
> _Originally posted by kromkamp_
> *If I were to use a parametric Eq to correct low frequencies (in my case 90Hz for example) on a full-range speaker, does it introduce phase errors across the entire spectrum or only around the center frequencies I am correcting?
> 
> 
> Andy K.*



A phase change is introduced on both sides of the frequency you are correcting.


It may be argued that this is not a phase error, but a phase correction. If the result of parametric equalization is a flatter spectrum, then the "distorted" spectrum of the room before EQ can be regarded as having incorrect phase, which the equalizer corrects. The resulting signal phase after parametric EQ will be the same as if the offending room modes weren't present to begin with.


----------



## kromkamp

Thanks Terry and Ethan. So, can you tell me why EQ is considered a last resort then? I agree that it doesnt solve the 'ringing' and long decay of problem frequencies, but I've always always read that EQ causes phase distortions which lead to a 'smearing' of the sound.


Andy K.


----------



## Terry Montlick

Andy,


Acoustic correction should always be attempted first, if at all possible. The problem with EQ is that it can only improve a localized area. Very low frequency absorption will improve the entire room, so there will not be seating issues.


While bass traps will improve a room and are advisable, a room with serious low frequency problems cannot be completely corrected without Herculean measures -- devoting a very major portion of the space to bass trapping. While possible for a studio, this is generally not a practical alternative for a home theater due to space, aesthetic, and/or budgetary considerations.


EQ is the next step after acoustical correction. In many cases, though, it can fix a room which is simply too problematic for completely effective very low frequency acoustic treatment. Unfortunately, the latter is the rule rather than the exception.










Regards,

Terry


----------



## Ethan Winer

Bob,


> I thought there were several types of phase shift (time delay > 1ms) 
subwoofer phase shift control knob


----------



## Ethan Winer

Andy,


> I've always always read that EQ causes phase distortions which lead to a 'smearing' of the sound.


----------



## Tweakophyte

Hi-


How kid and pet friendly are these materials? Do you need to cover them? Do they pull apart if messed with? Is one better than the other?


I am concerned with the stuff you put on the walls (versus in the walls).


Thanks,


----------



## gels

Jeff over in another new HT suggested I repost this here.


I'm hoping to start my HT early in January and am quite excited but know very little about acoustics, but no doubt after reading through and following this thread I hope to be up and running











Just wondering:


Would it be possible not the mud and finish the sheet rock especially as the CertainTeed UltraDuct Gold covers the walls??? I can certainly do the framing and sheet rock but would Never dare do the mud and tape work - lol


Thanks so much for your advice.


Cheers,


Geoffrey


----------



## bpape

You really should do the joints with tape and at least a rough mud job even if it is going to be covered. You wouldn't have to sand it though or worry too much, just seal up the joints.


Good luck.


----------



## gels

Thanks bpape:


I'll certainly take your advise and thanks again.


Cheers,


Geoffrey


----------



## JamesE

I recently bought some Owens Corning 2 inch 703 from a roofing wholeseller for about 50 cents a sq. ft. They carried OC shingles and were able to get all OC products.


----------



## marjen

Man around here they are charging over $1 a sq. ft for any rigid fiberglass. I have called about 30 places and only 2 carry it so far. Ordering online would be more expensive do to shipping. This stinks.


----------



## JamesE

Sorry, it was over 1 per sq ft. I just thru it out there as an option for getting the stuff. If you can just have it thrown on a load that is already coming in, the shipping isn't much.


----------



## BasementBob

marjen:


> Quote:
> Man around here they are charging over $1 a sq. ft for any rigid fiberglass.



Some people have been successful bartering over the price, offering to pick it up, etc. For example, one guy in england bartered from $1.50 per square foot down to $0.30 a square foot.


----------



## David Luks

Help:


I can not find INSUL-Shield but I have found Owens Corning SelectSound Black in blanket form for about $216.00 for a 48"X100' roll.


Can I get a couple of quick opinions on using this instead of the INSUL-Shield?


Thank you,


Dave


----------



## HuskerHarley

My room is 20 by 14 by 7.5 I'm going to try and find some of the material listed at the very beginning of this thread.


If I'm able to find THIS in the rigid form would it look OK to leave it uncovered?


My system will be 7.1, 6 of the speakers will be floor standing towers.


I must admit that this is all very confusing (figuring out which method of treatment to use).


I intend to use the room approximately 90 percent of the time for home theater.


So this is what I plan on doing (correct/stop me if I'm wrong)


Cover the entire front wall with 1 inch and the other three walls to match the height of my speakers.


Cover the bottom of the soffit with 1 inch as well.


HH


----------



## bpape

I guess you could leave it uncovered - it seems to be designed for that.


The perimeter of the room should be done to ear level - not to the top of the speakers necessarily.


Don't forget to do the first reflection points.


----------



## HuskerHarley




> Quote:
> _Originally posted by bpape_
> *I guess you could leave it uncovered - it seems to be designed for that.
> 
> 
> The perimeter of the room should be done to ear level - not to the top of the speakers necessarily.
> 
> 
> Don't forget to do the first reflection points.*



I would like to cover with fabric but I don't have the skills to do it right and haven't found a GOOD tutorial on DIY with pictures.


I will do ear level.


Doesn't ear level on three walls take care of the First reflection points?


HH


----------



## Carlton Bale




> Quote:
> _Originally posted by HuskerHarley_
> *My room is 20 by 14 by 7.5 I'm going to try and find some of the material listed at the very beginning of this thread. If I'm able to find THIS in the rigid form would it look OK to leave it uncovered?
> 
> 
> I intend to use the room approximately 90 percent of the time for home theater.
> 
> 
> So this is what I plan on doing (correct/stop me if I'm wrong)
> 
> 
> Cover the entire front wall with 1 inch and the other three walls to match the height of my speakers. Cover the bottom of the soffit with 1 inch as well.*



I'm in the exact same situation. Today, I will have 60 of the 2 ft x 4 ft black acoustic panels delivered. I will be applying them to the front wall, primary reflection pionts, around the perimeter at and below ear level, and on the bottom of the soffit. I'm not sure if it looks acceptable without a fabric covering but I hope so. I'll let you know after I see it tonight.


----------



## HuskerHarley




> Quote:
> _Originally posted by Carlton Bale_
> *I will have 60 of the 2 ft x 4 ft black acoustic panels delivered.
> 
> 
> I'll let you know after I see it tonight.*



How much do they cost?


Please post a picture if you can.


HH


----------



## bpape

The insulation up to ear level gets the majority. Don't forget the ceiling though.


----------



## HuskerHarley




> Quote:
> _Originally posted by bpape_
> *The insulation up to ear level gets the majority. Don't forget the ceiling though.*



Please tell me what I should do so I get it somewhat correct the first time.


HH


----------



## bpape

You'll be fine on the walls. Some do the ceiling, some don't. If you want to calculate where to put them (mirrors are a lot harder on the ceiling!







), draw it out. If you measure from the mid/tweeter center to the ceiling and then draw a phantom ABOVE the ceiling the same distance, then draw a line from that point to your ears, you have the hypotenuse (sp?) of a triangle. The other sides of it are the straightline distance from the real speaker to your ears and double the distance from mid/tweet to the ceiling.


Once you get that triangle trigged out, then you know the angles. From there, calc the triangle (phantom) above the ceiling and use the base for the distance from the speaker front out toward you. From side to side, put it in a straight line between you and the speaker.


This seems like a lot of math to some but to me it's easier than trying to get someone else to hold a mirror of decent enough size that I can actually see anything flat on a ceiling and move it around without being in the way.


----------



## HuskerHarley




> Quote:
> _Originally posted by bpape_
> *You'll be fine on the walls. Some do the ceiling, some don't. If you want to calculate where to put them (mirrors are a lot harder on the ceiling!
> 
> 
> 
> 
> 
> 
> 
> ), draw it out. If you measure from the mid/tweeter center to the ceiling and then draw a phantom ABOVE the ceiling the same distance, then draw a line from that point to your ears, you have the hypotenuse (sp?) of a triangle. The other sides of it are the straightline distance from the real speaker to your ears and double the distance from mid/tweet to the ceiling.
> 
> 
> Once you get that triangle trigged out, then you know the angles. From there, calc the triangle (phantom) above the ceiling and use the base for the distance from the speaker front out toward you. From side to side, put it in a straight line between you and the speaker.
> 
> 
> This seems like a lot of math to some but to me it's easier than trying to get someone else to hold a mirror of decent enough size that I can actually see anything flat on a ceiling and move it around without being in the way.*



I grew up in the crayon age and I'm embarrassed to say but I don't understand most of what you instructed me to do.


HH


----------



## bpape

Then get a stepladder, a decent sized mirror, a good patient friend, and some beer (not till after the mirrors are down







) and find them that way.


It's tough to describe a math problem for 2 - 2 dimensional triangles in a 3 dimensional space with just text.


----------



## mikemav




> Quote:
> _Originally posted by HuskerHarley_
> *How much do they cost?
> 
> 
> Please post a picture if you can.
> 
> 
> HH*



Agreed, curious about looks (uncovered) and cost. Thanks!


----------



## mikemav

Couple of questions in the early planning stages of my theater.


What do you think of pre-made acoustic panels like these ? Are they good performance-wise? My company can get them as a dealer, and I like the way a darker color GOM covered panel looks on a black lower wall. If I got some 4'x4' or 4'x longer, and did them across the bottom, would an inch or more of space in between each panel for aesthetics hurt performance much? I think butting them right up to each other might look strange, but spaced slightly apart, they kind of look like art. How about some idea on cost for the "right" way to do it, with GOM fabric stretched over the JM duct liner stuff? Any idea about how much it costs to do it that way for a room 14'x 18' to 4' high? I would prefer to just do a moulding at the top & paint above instead of fabric all the way up if I use the fabric method. I will be having a GC build the room. So I would need to factor cost of materials and understand if an average competent GC can install this stuff & how long it might take. The pre-made panels are in the range of $280 for 4' x 10' so that gives me an idea to compare against. Let's leave the front wall out of the equation for now as I will need to treat it either way. And that brings me to my next issue:


I will be moving a very nice family room projection system into a new dedicated room. More info & pics of current setup here Note I have not updated that thread yet, but I am now thinking of abandoning the dual front/ rear two sided projection. I will update that thread as to why. Still not 100% sure.


Regardless, I LOVE my rear projection image and deep blacks I get from the screen, and think I now want to use that in my new dedicated theater if I can swing it. The question is how will it impact the acoustics (I'm guessing not well) and what if anything can I do to help? The screen is 80"x45" and it is 1/2" thick optical rear projection glass (not plexi.) It will go into a wall that is probably about 14' wide. It will have a rear projection room behind it. Glass screen framed into that separator wall like a window. I can treat that wall (and the back side too, if necessary) with whatever will help. But of course, unlike most of you, I cannot treat the area behind the screen, as the screen is glass.


Other info: the room will probably be about 17' to 18' deep. I have two full range tower L/R speakers w/ 12" sub/10" passive radiator for mains. One additional 15" stand alone sub. Thinking two rows of 3-4 seats each, back row on small riser. Probably a modified stage with three decoupled sections, sides filled w/ sand & middle w/ insulation (this is not on ground level.) Ceiling height to be 8' range, with two small areas about 17" lower. Screen (if I go RP, or keep my original dual FP theater/ RP family room idea) will be on the lower side, about 29" AFF due to where the RP screen is now. Actually, if I build the RP room over I can make that higher if needed. So I could put the center above or below.


Any info or tips on these issues for planning my acoustics most appreciated. Also, are there any good room planning software programs out there that are free or close to it, so I can play around with ideal room dimensions and seat/speaker placement while in the planning stages?


----------



## bpape

I've seen those from Acoustics First before. Unfortunately, they do not list individual absorbtion numbers at different frequencies. They also specify that they use 'high density fiberglass'. Generally, something around 3pcf is desirable. Higher densities can have issues with being too reflective at higher frequencies. Without knowing the specs, it would be almost impossible to determine what they will do in your application.


----------



## Carlton Bale

I received my Owens Corning SelectSound Black 2 ft x 4 ft panels yesterday; pictures are below. This is probably the best looking non-covered fiberglass panel there is, but I still don't think it is quite nice enough to hang on the wall uncovered, due mostly to the edges showing but also because the front isn't completely smooth and uniform. The front isn't too bad, but it's not as nice in appearance as a fabric covering would be. I'll probably cover mine with black grill cloth.


Front:







Back:










Side:


----------



## rudee

can anyone help with this scenerio?

I'm using the Danzian Celtic Cloth for an accoustically transparent screen (54"x96") with three in-walls for the LCR duties. The room is sorta large @ 24x24x8 and right now, the in-walls are pretty close with maybe a 1/4" gap between the screen fabric & front speaker baffle. Should i be concerned with treating the whole front wall or the area just behind the screen with a deadening material? Should i "float" the screen out and away from the speakers more than they are now even if i do/don't treat the area behind the screen?


rudee


----------



## Ethan Winer

Rudee,


> The room is sorta large @ 24x24x8 ... Should i be concerned with treating the whole front wall


----------



## Scott Jelsma

Ethan, I have a couple of questions about your previous post to Rudee. Please forgive me if these questions sound like I'm a novice. I am.


First, does it matter that Rudee's room has a huge resonance specifically at 71 Hz, and also at 24 and 47 Hz, as compared to having resonances at some other frequency? Let me explain where I'm coming from with this question... I have done quite a bit of reading on your web site at realtraps.com about bass traps. (By the way, the educational information and videos you provide are amazing!) Based on my understanding of your video on "Non-modal peaks and nulls in small rooms", it really doesn't matter what the resonances are related to a room's dimensions. Your video seems to prove to me that all rooms need broadband bass trapping and not trapping at specific frequencies. So would Rudee's room be treated any differently than a room that had equally huge resonances at some other frequency?


My second question is this, Would you treat a room differently if it has "huge" resonances at some particular frequency (like Rudee's), vs. a room that has more moderate resonances? Again, let me explain where I'm coming from with this question... Your educational materials indicated to me that you believe most rooms need 8 to 10 broadband base traps placed in corners. Is this true regardless of the bass problems that a room has, or is this an average? Would a room like Rudee's need more panels, or would the recommended 8 - 10 be sufficient?


Finally, I know the broadband bass traps ideally should go in the corners. However, if I place 8 - 10 traps in my room, does it matter if they are equally disbursed? For example, if due to aesthetics or practicality, I can not put a trap in one particular corner, Can I double-up in another corner to compensate? (By "double-up", I mean stack the traps so they cover the entire 8 foot tall area in the corner.) Or even more drastically, could I put all eight in the corners behind the proscenium and get satisfactory results?


----------



## rudee

wow - i hope all the questions above get answered b/c inquiring minds want to know! I have often thought what dreadful things were happening in here due to the square vs rectangle dimensions so often mentioned . The room doesn't sound half bad as is...

I am running a two tempest i/b located dead center between the mains in the front of the room and about 24" into the room and since it's an ib it's not going anywhere. Here's the very first frequency response i ran a few weeks ago.

Numbers below:

HZ r/s meter adjusted

17.5 80 87.3

20 88 94.2

22 88 93.4

25 88 84.4

28 80 79.6

32 72 75

36 80 82.5

40 80 82

45 92 93.7

50 102 103.3

56 102 103

63 104 104.8

71 106 106.7

80 102 102.5

89 106 106.4

100 112 112.3

112 91 91.25

126 95 95.2


sorry i don't know how to insert the graph but the numbers show a good dip from 25 to 45. These are the first numbers i have ever taken in this room and will be doing more testing as time permits. I'm thinking of doing a built in trap in each front corner as seen in some of the links on bobgolds site with oc 703 or equal. I didn't think the raw room numbers were too bad- i do have a bfd to help in the end but i wanted to address the room to some extent.

ethan, to the trained eye are my numbers relfecting the bad things you say are happening to the lower frequencies in this size space?



rudee


----------



## mikemav




> Quote:
> _Originally posted by mikemav_
> *clip...
> 
> 
> I will be moving a very nice family room projection system into a new dedicated room. More info & pics of current setup here Note I have not updated that thread yet, but I am now thinking of abandoning the dual front/ rear two sided projection. I will update that thread as to why. Still not 100% sure.
> 
> 
> Regardless, I LOVE my rear projection image and deep blacks I get from the screen, and think I now want to use that in my new dedicated theater if I can swing it. The question is how will it impact the acoustics (I'm guessing not well) and what if anything can I do to help? The screen is 80"x45" and it is 1/2" thick optical rear projection glass (not plexi.) It will go into a wall that is probably about 14' wide. It will have a rear projection room behind it. Glass screen framed into that separator wall like a window. I can treat that wall (and the back side too, if necessary) with whatever will help. But of course, unlike most of you, I cannot treat the area behind the screen, as the screen is glass.
> 
> 
> Other info: the room will probably be about 17' to 18' deep. I have two full range tower L/R speakers w/ 12" sub/10" passive radiator for mains. One additional 15" stand alone sub. Thinking two rows of 3-4 seats each, back row on small riser. Probably a modified stage with three decoupled sections, sides filled w/ sand & middle w/ insulation (this is not on ground level.) Ceiling height to be 8' range, with two small areas about 17" lower. Screen (if I go RP, or keep my original dual FP theater/ RP family room idea) will be on the lower side, about 29" AFF due to where the RP screen is now. Actually, if I build the RP room over I can make that higher if needed. So I could put the center above or below.
> 
> 
> Any info or tips on these issues for planning my acoustics most appreciated. Also, are there any good room planning software programs out there that are free or close to it, so I can play around with ideal room dimensions and seat/speaker placement while in the planning stages?*



Sorry to bump, but I could really use some advice. Does anyone have any thoughts on how badly the glass RP screen will impact acoustics, or ideas to help? I need to make a decision later this week on which direction to go:

keep the RP screen for the family room & drop down a custom motorized front screen in front of it for the new theater room side (original idea in my post.) That screen would be custom built much like a blackout shade, and rise/lower in side channels to block light from coming from behind.

Or I may move the RP screen into the theater and bag the dual room idea, if I can find enough room for an RP booth and seating area in the new space.

Option three is to just go front projection in the new room like most people do, and that would make for best acoutsics, but that would mean wasting the $700 RP screen and custom integration I have now (and paying extra to have it removed.)

So the real question is, will an RP screen w/ a front screen directly in front if it be horrible for the sound or is there some way to deal with it? What do you think?


----------



## Ethan Winer

Scott,


> does it matter that Rudee's room has a huge resonance specifically at 71 Hz, and also at 24 and 47 Hz, as compared to having resonances at some other frequency? 
Based on my understanding of your video on "Non-modal peaks and nulls in small rooms", it really doesn't matter what the resonances are related to a room's dimensions. 
So would Rudee's room be treated any differently than a room that had equally huge resonances at some other frequency? 
Would you treat a room differently if it has "huge" resonances at some particular frequency (like Rudee's), vs. a room that has more moderate resonances? 
if I place 8 - 10 traps in my room, does it matter if they are equally disbursed? 
if due to aesthetics or practicality, I can not put a trap in one particular corner, Can I double-up in another corner to compensate?


----------



## Ethan Winer

Rudee,


> to the trained eye are my numbers relfecting the bad things you say are happening to the lower frequencies in this size space?


----------



## Ethan Winer

Mike,


> how badly the glass RP screen will impact acoustics


----------



## mikemav




> Quote:
> _Originally posted by Ethan Winer_
> *Mike,
> 
> 
> > how badly the glass RP screen will impact acoustics*


----------



## ChrisWiggles




> Quote:
> Unless your speakers are pointing directly at the glass it's probably not a problem. Otherwise it's just one more reflective surface out of many others in the room.



I disagree. I've not played around with RPTVs which are smaller, but I will be including some movable thick curtains or panels for when I'm listening to music because my screen (FP, non-acoustically transparent) definitely damages the imaging and flattens the depth front/back.


----------



## rudee

ethan thanks so much for the further detail.

From the questions asked answered by you i can assume the following:

With the size of my room and the overall dimensions i have my work cut for me for getting this room treated to tame these ugly things- which is okay cause i'm at the point i'm ready to address the room.


I will go at it a bit blindly in the beginning and hopefully be able to devote more time to some of the room calc software as time permits.


-bass traps in corners- i can do both fronts and one rear fully and only a small top corner due to cabinets in the fourth corner. From what i gather i need heavy trapping- the denser the better?


-treat the whole front wall with a 1" oc 703 type material or linacoustic covered with a GOM or similiar material.


-treat the bottom half of the wall with a 1" oc 703 type material or linacoustic covered with a GOM or similiar material.


I could make a soffit trap using three sided wedges of compacted rigid fiberglass material wraped with GOM or simiar around the two side walls & rear if it would help do the trick in this room- Is there any chance this would be too much damping?


thanks much-

rudee


----------



## HuskerHarley

I have found a local place to purchase OC 703 or 705 & would like to see a detailed DIY Tutorial or guide that show's how to do EVERY step, especially how to cover with fabric.


I don't have the funds to hire some one to TEST my room for proper placement/location for the 703, so I will cover entire front wall and sides and rear to ear height.


Would it matter if I only covered from top of wall plates (electrical ect.) up to ear level (44"-48") for the sides & rear?


My room is 20'X14'5"X7'9" (LWH)


HH


----------



## ChrisWiggles




> Quote:
> & would like to see a detailed DIY Tutorial or guide that show's how to do EVERY step, especially how to cover with fabric.



I think once you get it you'll realize it's pretty easy to figure out. The two main ways that are used are a spray on glue and fabric right onto the fiberboard, or to make some kind of simple frame (or you can make it a spiffy elaborate frame if you so desire).


I just used a really cheapo frame idea, just a bunch of 1x4 boards nailed together, put the fiber board in there, and staple-gunned the fabric to it. I have no woodworking skills, so I went uber-simple. The only difficult thing was that home depot wood is total crap so the boards were warpy or would split, so I spent a few bucks for some little L brackets for a couple corners. Really easy.


----------



## HuskerHarley




> Quote:
> _Originally posted by ChrisWiggles_
> *I think once you get it you'll realize it's pretty easy to figure out. The two main ways that are used are a spray on glue and fabric right onto the fiberboard, or to make some kind of simple frame (or you can make it a spiffy elaborate frame if you so desire).
> 
> 
> I just used a really cheapo frame idea, just a bunch of 1x4 boards nailed together, put the fiber board in there, and staple-gunned the fabric to it. I have no woodworking skills, so I went uber-simple. The only difficult thing was that home depot wood is total crap so the boards were warpy or would split, so I spent a few bucks for some little L brackets for a couple corners. Really easy.*



Do you have pictures..










Did you make several frames and butt them side by side all the way around the 3 walls or did you leave gaps?


HH


----------



## BasementBob

HuskerHarley


> Quote:
> Do you have pictures



Have a look at http://www.bobgolds.com/AbsorptionCoefficients.htm and scroll down about 85% of the way and click on all the links from
_Jon Risch's Absorbers_

through
_Vshine's Wall Absorbers_.

That should give you some ideas


----------



## HuskerHarley




> Quote:
> _Originally posted by BasementBob_
> *HuskerHarley
> 
> 
> Have a look at http://www.bobgolds.com/AbsorptionCoefficients.htm and scroll down about 85% of the way and click on all the links from
> Jon Risch's Absorbers
> 
> through
> Vshine's Wall Absorbers.
> 
> That should give you some ideas*



Thanks for the link..










Lot's to digest there.


I get the impression that I don't need to cover entire front wall and not cover other 3 sides all the way around to ear height after looking through those sites...Very confusing based on info in this thread...










HH


----------



## BasementBob

HuskerHarley

This forum talks a lot about home theatre with 5.1 to 7.2 sound.

The links on my site include stereo for musicians.

I provided the links to show examples of manufacture of panels, not about placement, nor quantity.


----------



## loquatsoft

By looking at the http://www.bobgolds.com/AbsorptionCoefficients.htm chart, should 703 2 FRK be the best solution for bass absorption but not overkill the high frequency?


----------



## Carlton Bale




> Quote:
> _Originally posted by loquatsoft_
> *By looking at the http://www.bobgolds.com/AbsorptionCoefficients.htm chart, should 702 2� FRK be the best solution for bass absorption but not overkill the high frequency?*



I believe the general consensus is that 2" material provides too much absorption in the mid-bass range. To adequately absorb high frequencies, a certain % coverage of wall surfaces within the room is required. Using the 1" material results in the desired performance; using the same amount of 2" material would provide too much mid-bass absorption and using less 2" material would start to provide too little high frequency absorption. This is the way I understand it, but I'd like to hear confirmation from someone with more experience.


----------



## Terry Montlick




> Quote:
> _Originally posted by loquatsoft_
> *By looking at the http://www.bobgolds.com/AbsorptionCoefficients.htm chart, should 702 2� FRK be the best solution for bass absorption but not overkill the high frequency?*



Do you mean 703 instead of 702? Owens Corning 702 is not a standard product.


The answer is "it depends."










There is mounting away from the wall, which is always better for low frequencies. There is faced (FRK) vs. unfaced, where faced with the facing mounted towards the room will reflect high frequencies but absorb low frequencies.


And there is also a grain of salt to be taken with any absorption coefficient chart. While these are nearly always made using certified laboratory data, there is also a fair amount of variation in measured absorption coefficients using the standard Reverberation Room method. There is significant variation from lab to lab, and even variation for samples measured in the same lab. So consider the coefficients good to only one decimal place, even though they are given for two!


- Terry


----------



## loquatsoft

Carlton,

Seems like OC 703, FRK 2" even outperform the 703 1" plain on the midrange.

Terry,

Will you recommend the FRK (Foil reinforced kraft)? "This facing consists of an aluminum foil laminated to a kraft paper backing reinforced with a fiber glass scrim (yarn)"


----------



## Clarence

Here's a chart I made to try to choose between the 1" and 2" OC's.


But instead of helping, I think I'm jut more confused because I still don't know how much is too much and how little is too little.


703 plain 1" (pink line) is what I was origninally looking at, and it still looks fine in comparison...


----------



## bpape

It's only too much or too little in comparison to a furnished room full of people. You can't decide just based on these numbers. You have to know what your room needs, where it will be applied, etc.


----------



## ptwood

I am not sure if his is covered elsewhere in the forum but I plan to use the GOM fabric on the 703 and used speay adhesive and works fine,I also plan to use the same fabric on the upper part of wall (above 2 panels of 703 ) my question- what method have those of you who have applied this fabric to the wall applied it I wastold I should use the same spay adhesive, but definitely not wall paper paste, any help is appreicated

Peter


----------



## ptwood

I am not sure if this is covered elsewhere in the forum but I plan to use the GOM fabric on the 703 and used speay adhesive and works fine,I also plan to use the same fabric on the upper part of wall (above 2 panels of 703 ) my question- what method have those of you who have applied this fabric to the wall applied it I wastold I should use the same spay adhesive, but definitely not wall paper paste, any help is appreicated

Peter


----------



## loquatsoft

I was so surprised by the mighty 703. It really works. Now I can enjoy the deep bass that I'm longing for and it allows my 12 sub to do its work. Thanks you all(including OC).


ptwood, will you let me know how you do it(GOM) once you figured it out?


----------



## ptwood

I hae another question, I have seen recommendation to put the adsoring 703 style panels on lower portion of walls, I was planning to just do GOM glued to walls above but found pictures and references to use a poly batting material above and cover this with GOM, can anyone comment on what this does

Thx for any help, if this is way to go then won't ned to glue

Thx


----------



## ptwood

I hae another question, I have seen recommendation to put the adsoring 703 style panels on lower portion of walls, I was planning to just do GOM glued to walls above but found pictures and references to use a poly batting material above and cover this with GOM, can anyone comment on what this does

Thx for any help, if this is way to go then won't ned to glue

Thx


----------



## Terry Montlick

Polyester batting provides additional sound absorption, though not as much as 703 for the equivalent area.


- Terry


----------



## ptwood

Thank you Terry I appreciate your reply, would you suggest just going ahead using the batting in addition to the 703 (top portion of the wall and about 2 panels of 703 hung horizontally) or shall I check room and go from there,

also I have soffitts (6-7 inches vertical 18 inches, horizontal) all around the room as well as columns on the side and rear walls holding the surround speakers should these be filled with insulation (mineral wool, fiberglass batts...?) any suggestions

Thank you

Peter


----------



## HuskerHarley

DIY VS REAL TRAPS


Besides the obvious difference in cost between REAL TRAPS and DIY OC 703 designed Traps.


Do they both deliver what were after?


I want to save money but I'm not sure if the DIY route would deliver what the REAL TRAPS promise to deliver, are the REAL TRAPS using the same insulation or do they have something special inside to separate them from the DIY versions.


In my situation money matters but I don't want to waste it doing a DIY that won't deliver what I'm after...


Convince me that DIY is as good as REAL TRAPS or just a few percentage points away from being as good.


HH


----------



## loquatsoft

The article Room Acoustics: Acoustic Treatments- Absorption is quite interesting. But the following statement get me all confuse. Maybe they use something more sophisticate than the OC703.

Note that 1 acoustical panels only work down to 1000Hz which is above most of the primary vocal frequencies and thus just about useless in affecting vocal intelligibility. Two inch material gets down to 500Hz or so and 4 down to 250Hz. 
http://www.audioholics.com/techtips/...reatments3.php 


-------------

Adam


----------



## Terry Montlick




> Quote:
> _Originally posted by loquatsoft_
> *The article �Room Acoustics: Acoustic Treatments- Absorption� is quite interesting. But the following statement get me all confuse. Maybe they use something more sophisticate than the OC703.
> 
> �Note that 1� acoustical panels only work down to 1000Hz which is above most of the primary vocal frequencies and thus just about useless in affecting vocal intelligibility. Two inch material gets down to 500Hz or so and 4� down to 250Hz. �
> http://www.audioholics.com/techtips/...reatments3.php
> 
> 
> -------------
> 
> Adam*



Hi Adam,


It's not the material (703) but the way in which it is mounted which makes a huge difference in bass absorption. That article assumed you were mounting the absorber right against the wall ("A" mounting). If it is spaced away from the wall, the extra depth provides a very effective way to absorb the longer, low-frequency wavelengths. Ditto for corner mounting, which gives a continuous range of depths.


- Terry


----------



## bpape

I'll let Ethan describe exactly how the RealTraps are put together since it's his product.


Also understand that the recommended mounting for RealTraps is @ 45 degrees across a corner or at a tri-corner. They can be mounted other places but will not yield the bass absorbtion in that confiburation.


Standard 703 will also yield good bass trapping when placed @ 45 degrees across a corner.


----------



## ptwood

Need some help from the experts on 703 vs 705 when I look at the ascoustical numbers comparing the 703 3#pcf vs 705 6#pcf the numbers don't llok all that much different for the 1" thick material, and the NRC value of plain (no facing) 703 is .70 and plain 705 is .65 (these nubers are when material is placed against a solid backing

willthe denser 705 be better - to get good numbers in the 125 and 250 octave range the 2 inch thick material 703 or 705 do much better

any comments pls

Thx

Peter


----------



## ptwood

Need some help from the experts on 703 vs 705 when I look at the ascoustical numbers comparing the 703 3#pcf vs 705 6#pcf the numbers don't llok all that much different for the 1" thick material, and the NRC value of plain (no facing) 703 is .70 and plain 705 is .65 (these numbers are when material is placed against a solid backing

willthe denser 705 be better - to get good numbers in the 125 and 250 octave range the 2 inch thick material 703 or 705 do much better

any comments pls

Thx

Peter


----------



## krasmuzik

You need to do the reverb calculation for your room and see if you need better bass numbers (125Hz and 250Hz) or not. All depends on the overall treatment, furnishings and architecture of your room.


There is no such thing as better numbers when it comes to acoustical treatment - rather are the numbers what you need, or can you revise your treatment to make the numbers fit your room based on what you can get.


Also consider that a 0.1 delta in numbers is meaningless - combined with corner-backed vs. hard-backed treatment are entirely different numbers. Good luck getting standardized corner-backed numbers - as no standard exists for that measurement!


----------



## Ethan Winer

Adam,


> Maybe they use something more sophisticate than the OC703.


----------



## Ethan Winer

Peter,


> will the denser 705 be better


----------



## krasmuzik

Ethan,


Interesting read.


Your ETF measurements are maxing out at 100dB. It assumes the max response is that for each graph unless a SPL meter has been used to calibrate the mike reading and entered into ETF. This would make the charts more comparable.


----------



## audiguy

Great thread guys. It has taken a couple of weeks, but I now have made it through the entire 17 pages of the post and know a lot more about this subject than I ever thought I would. The post has caused me to have four more questions that hopefully, you experts can field. As a matter of background, I have a bonus room with a HT/Stereo in it (TAW 3 chip, Theta Casablanca, Vandersteen, etc). This is not one of those dedicated jobbies like most of the guys on this post are doing. It started out as a bonus room and it is still a bonus room, though I am taking it over bit by bit. I use it quite a bit more for HT than for music (now that we can watch "24" and the like in HD on the big screen, usage has gone up! But I am far more critical of the sound with music. I would never think of giving up anything on the music front for the HT. I am getting around to the acoustic treatment part of the program and read this thread. So here are my questions. Your insight is appreciated.


1. On the subject of the OC 703/back and side walls/music vs. HT and you can't have both...I read in one of the posts that the 705 was a little more reflective and absorbed bass better. Wouldn't I possibly prefer it to the 703 on the side walls if music is important?


2. I know a lot more than I did before I read this thread, but I am by know means more sure of myself. Would it not be smarter to just pay an expert to come look at my situation and tell me what to do? OR....


3. Instead of planning this thing out to the hilt, considering the fact that I can screw up two ways...too much OR too little dampening...why wouldn't I just design it as I go. In other words, why wouldn't I put some panels on the back and the sides (first reflection included), then I listen to it. See it I like it. And if I don't, put on some more. Then I put in a bass trap, see if I like it and if I don't, put in some more. I am pretty much thinking that I will standardize on some sort of frame size like 2 X 8 feet. And finally,


4. The right side of the room (9 1/2' X 23') is completely void of any insulation. Upon banging on it, it acts like quite the bass drum. Seems to me like this can be a problem and/or an opportunity. Should I fill this wall with insulation? Will it do any good? I am thinking that it will slow that wall down from acting like a drum and if I am lucky make it act like one of those bass traps that Ethan was talking about.


Thanks in advance for your advice.


Randy


----------



## Ethan Winer

Kras,


> Your ETF measurements are maxing out at 100dB


----------



## Ethan Winer

Randy,


> Wouldn't I possibly prefer it to the 703 on the side walls if music is important? 
why wouldn't I just design it as I go


----------



## krasmuzik

Ethan Winer


But those measurements are not relative - they are scaled.


Assume you measured the empty room and the max modal peak was 100dB.


Assume you put in the bass traps and damped down the max modal peak to 80dB.


When you measure again with ETF with the bass traps - the max modal peak will be again 100dB.


The max peak in ETF is always 100dB without calibrating with the SPL meter. Otherwise it has no idea what the sound card numbers mean - and it does not relate subsequent measurements to prior measurements.


Look closely at your charts - they are all max peak 100dB (sometimes right at the last frequency so hard to see)


So the charts are only relative with themselves - not each other. So the charts can tell you that the second highest peak is 20dB less than the highest peak on the same graph. But they cannot tell you is did this or that fiberglass - raise or lower the peak by 6dB?


----------



## audiguy

Ethan-


Thanks for the response and the help. I think what I am going to do is use my 703 for bass traps and first reflections, and then when I need to buy more for phase two, I will use 705.


A couple of follow ups.


First, what is a ballpark amount for a designer to come advise me as to what to do?


Second, as far as the wall with no insulation (I didn't say, but I meant inside of the wall), I don't have access to the other side, but I can access the inside of the wall. Wouldn't I just want to take regular un-face batting and stuff it down in there?


Thanks for your help.


Randy


----------



## krasmuzik

audiguy


You can find audio calibrators at www.homeacoustics.net that can plan/measure your acoustic treatment. Expect to pay more than your average AV wire puller would make. The most basic service offered is the Acoustic Design Review - they will just go over your room plan and make up a checklist of the most important things to do in your room.


----------



## Brian Ravnaas




> Quote:
> _Originally posted by krasmuzik_
> *Ethan Winer
> 
> 
> But those measurements are not relative - they are scaled.
> *



hey kraz, everybody


if i can offer a thought: they are both


the scaling to the 100dB default for uncalibrated mic makes them scaled, yes, but you can still observe the decay rates at each of the modes and compare them relatively.


you can also still see (and i'm sure ethan's files would let this be explored more by him) the relative sharpness/roundness of the modal peaks and nulls


and i think that Ethan's experiment accomplishes his goal of relative comparison. Or, a better way to put it would be how he did in some post or other "a first step" towards understanding these twin phenomenon - FRK and density.


i like Ethans test, from what i gather in the description on his page, they took care to ensure that they changed one variable here, and not many.


g'day all


Brian


----------



## Ethan Winer

Kras,


> So the charts are only relative with themselves - not each other. 
So the charts can tell you that the second highest peak is 20dB less than the highest peak on the same graph. But they cannot tell you is did this or that fiberglass - raise or lower the peak by 6dB?


----------



## Ethan Winer

Randy,


> what is a ballpark amount for a designer to come advise me as to what to do?


----------



## Ethan Winer

Brian,


> i think that Ethan's experiment accomplishes his goal of relative comparison. Or, a better way to put it would be how he did in some post or other "a first step" towards understanding these twin phenomenon - FRK and density.


----------



## krasmuzik

Ethan


If things are just shifted to max 100dB - then the decay times are still valid. But if they are scaled to max 100dB then they are not.


Lets assume that the real SPL peak was 60dB and it decayed to nothing in 1s. Thus RT60 for that mode is 1. But in ETF it reads the SPL peak of 60dB as 100dB max since it has no idea what the real SPL is - but it does not scale time so it still decays to nothing in 1ns. But that means RT60 for that mode from ETF is 0.6s - even though in SPL terms it is 1s.


I like the idea of the experiment - it is just I don't know what to conclude from it because I don't see how any of the graphs are comparable with other graphs - as none of them have the same scale.


To me this is like using autoscale in Excel Graphs - but then leaving the Yaxis labels off.


Maybe I am misunderstanding and TF dB steps DO correlate to SPL steps - but it just does not know the peak value to use without calibration (better to represent peak as 0dB then - and everything else as -dB from peak). Maybe this is something Doug from AcoustiSoft can answer.


----------



## Brian Ravnaas

hey again everybody,


the decay times, as viewed on the bottm of the plots can be skewed, yes, by this scaling.


however, what we want is the decay rate, or in a waterfall, for example, the # of decibels of decay per line of time coming toward you. And those comparisons - and there are some cases on EW's density page where it is obvious that things are faster - are still valid relative to one another.


i do not consider it impossible to attain a sabin figure from non-reverb room tests, but that's a wild tangent to this topic and i've not the time this evening.


pleasure reading everybodies thoughts,


Brian


----------



## BasementBob

Brian Ravnaas



> Quote:
> the # of decibels of decay per line of time coming toward you



Isn't krasmuzik's point that because the y scale is dynamic, you don't know the # of decibles of decay per line.


----------



## Brian Ravnaas

hey bob,


because the scale is random, the time (# of lines) where the decay enters the "floor" of the graph is misleading.


but waterfall plots do not innately skew the decay rate. Decay rate is not related to where any given peak enters the floor of the graph, but is related to the db/time, or db/line going forward.


you can't count lines starting at the top of the peak, you have to count the lines over some amount of decay, which you can loosely diving by drawing lines parallel to the various axis.


more ideally, you would calibrate the mic or find some way to make ETF (or alternate software) deliver a more direct answer as to what this decay rate was.


And i konw this topic borders, in places, on being so controversial that nobody even wants to talk about it or think about it, they just want it to be XXX or YYY, but... take a look at the definition of a sabin, and how it's calculated in ASTM C-423...


Brian


----------



## BasementBob

Brian Ravnaas


Just in case we're talking apples and oranges, I've made this little graph to show what I'm talking about.

By slope alone the graph on the right appears to have a larger decay rate when viewed on an ETF5 'artificial 100db all peak' scale (sub rights), but knowing the Actual Db scale (sub lefts), I think the graph on the left has the higher 'Actual' decay.

i.e. the left decays at 50db / 6 units of time, and the right decays at 8db / 4 units of time.













> Quote:
> more ideally, you would calibrate the mic or find some way to make ETF (or alternate software) deliver a more direct answer as to what this decay rate was.



Yea, that would be great.


----------



## Terry Montlick

Brian's right about the slope of a mode (dB over time) in a waterfall chart indicating its decay rate.


Bob, I'm afraid your example graph isn't right because dBs are logarithmic and scale by addition, not multiplication.


- Terry


----------



## BasementBob

Terry Montlick:



> Quote:
> Brian's right about the slope of a mode (dB over time) in a waterfall chart indicating its decay rate.



Yes, but it assumes that you know the db otherwise you don't know the slope.


With ETF5 waterfalls the y axis scale is always converted so that the peak is at a fake '100dB'. In my graphs I didn't show that peak, so above please assume that '100db' mark is somewhere else not shown on the graph, and that what is shown is two other peaks merely provided to show that the visual slope is independant of the actual slope/decay rate.


My point is that if you have two independant measurements (two ETF5 test runs), and are looking at the visual slope on the waterfalls, they can't be compared from one waterfall chart to the next waterfall chart because you don't know the real slope because the y axis isn't fixed/constant between them.


Within a single waterfall chart two peaks could be compared because the slope would be consistant, but that's not what we're doing today.



> Quote:
> Bob, I'm afraid your example graph isn't right because dBs are logarithmic and scale by addition, not multiplication.



I know dBs are logarithmic, but I'm afraid I (just me) don't follow that sentence.


----------



## Brian Ravnaas

hey bob,


the dB on the sides aren't the CORRECT values, for example, 100dB might actually be 77 or 89 or 107


but the decibel increments on the graph (each 3dB line) do represent 3dB.


hence the decay rate from picture to picture can be assessed.


it would be preferable to use another function of ETF to assess the decay rate in a more formal way, but the waterfalls do reflect the decay in a consistent manner from graph to graph. with the exception of how high on the plot each given mode/decay starts - that is arbitrary.


----------



## Terry Montlick




> Quote:
> _Originally posted by BasementBob_
> *
> 
> ...
> 
> I know dBs are logarithmic, but I'm afraid I (just me) don't follow that sentence.
> 
> 
> 
> 
> 
> 
> 
> *



It means that when ETF scales the y axis so that the maximum is 100 dB, it does so by adding a fixed number of dBs to the graph. As Brian said, a 3 dB change is always a 3 dB change. So scaling a graph upward by 30 dB means ADDING 30 dB to every point in the graph, not multiplying it by some factor.


- Terry


----------



## Ethan Winer

Bob,


> Isn't krasmuzik's point that because the y scale is dynamic, you don't know the # of decibles of decay per line.


----------



## krasmuzik

Brian Ravnaas, Terry Montlick, Ethan Winer


How do you know that a 3dB change in ETF - is indeed a 3dB SPL change?


Are you sure ETF (or mic input) does not have a gain expander function in there - as in the minimum reading is 0dB and the maximum reading is 100dB? Thus 3dBETF!=3dBSPL?


----------



## BasementBob

krasmuzik


> Quote:
> Are you sure ETF (or mic input) does not have a gain expander function in there - as in the minimum reading is 0dB and the maximum reading is 100dB? Thus 3dBETF!=3dBSPL?



The minimum on the ETF5 waterfall charts is always 70db.

The maximum on the ETF5 waterfall charts is always 100db

There are always points on both.


So I'll rephrase what you wrote a bit

_"Are you sure ETF (or mic input) does not have a gain expander function in there - as in the minimum reading is 70dB and the maximum reading is 100dB? Thus 3dBETF != 3dBSPL ?"_



BTW, Terry, Brian, Ethan -- I get what Terry meant now. Thanks.


----------



## Terry Montlick




> Quote:
> _Originally posted by krasmuzik_
> *
> 
> Are you sure ETF (or mic input) does not have a gain expander function in there - as in the minimum reading is 0dB and the maximum reading is 100dB? Thus 3dBETF!=3dBSPL?*



Yuck -- that would be a pretty nasty feature (bug!).


----------



## kromkamp

The waterfall plots go from 70db to 100db, but signals 'flat-line' at 70 ie. you can infer that the levels were measured to go below that the GUI just wont let you see it. Other plots will let you go below 70db.


If there was a 'normalization' function going on I would be really annoyed







You cant tell what the absolute SPL is at any frequency but I still believe you can tell it is exactly #dB larger than the frequency next to it.


----------



## krasmuzik

It could be a nasty feature of the sound card mic/line input - I use the ETF mixer which is supposed to bypass everything - but you can never be sure. ETF only cancels out frequency response errors with the feedback channel- but can never know if there is auto/nonlinear gain on both channels.


Yes indeed the waterfall plots have a waterline - just makes it easier to see the mountains without all the garbage on the ocean floor.


I sure hope it is the case the delta dBETF = dBSPL - but I have not seen any tests that (dis)prove that. Maybe this only occurs with SPL calibration in ETF.


For doing reverb/modal decay and Sabine calculations that would be important - but for just doing continuous measurements to see relative impact of a panel should not matter as long as you are aware of the dB shift to max peak=100dB.


But this max=100dB feature can get you into trouble - suppose you build a resonator to target a peak mode as some on here have been attempting. In reality the resonator could be successful at killing the peak - but now some other peak is at max=100dB - leaving you scratching your head - as that peak was not there before! Even though in reality the peak SPL dropped from 100dB to 80dB.


I have not checked continuous mode to see if it scales up to max 100dB. It seems it could use differences between readings to make better relative scales - at least within the same ETF session - so that you have max=100dB only once per session rather than per graph. But that would require that successive runs be able to show >100dB. Then the user would have to watch out for the continuous graph scale changing - which could itself be misleading.



So I still think it is worth doing the SPL calibration!


----------



## Ethan Winer

Bob,


> The minimum on the ETF5 waterfall charts is always 70db.

> The maximum on the ETF5 waterfall charts is always 100db


Not so! When displaying a waterfall graph, click the icon at the lower far-left of the window and you can set both limits to anything you want. That's why I suggested yesterday that maybe I should display my Density graphs again setting a new lower bottom limit to better see more of the decay.


--Ethan


----------



## Ethan Winer

Kras,


> suppose you build a resonator to target a peak mode as some on here have been attempting. In reality the resonator could be successful at killing the peak - but now some other peak is at max=100dB - leaving you scratching your head


----------



## Brian Ravnaas




> Quote:
> _Originally posted by Ethan Winer_
> *Bob,
> 
> 
> > The minimum on the ETF5 waterfall charts is always 70db.
> 
> > The maximum on the ETF5 waterfall charts is always 100db
> 
> 
> Not so! When displaying a waterfall graph, click the icon at the lower far-left of the window and you can set both limits to anything you want. That's why I suggested yesterday that maybe I should display my Density graphs again setting a new lower bottom limit to better see more of the decay.
> 
> 
> --Ethan*



that would be very interesting, Ethan.


also, are there any other means of presenting the data? like a frequency-filtered (filter between two of the nulls) "o-scope" view that would let you see the decay over time at a given frequency?


----------



## bpape

My God Brian - don't you ever sleep!?


----------



## Ethan Winer

Brian,


> a frequency-filtered (filter between two of the nulls) "o-scope" view


----------



## Brian Ravnaas

Ethan,


i guess the possible analogy with assessing mechanical damping via individual modes and peeking at absorber performance via individual modes has kind of intrigued me through all this discussion.


i understand if you're not interested, but you can mail me at [email protected] , and if you don't mind emailing the files (i'm sure they are huge) i'll take an hour and try to process them on some equipment here at the lab. ASCII files or .wav files, if they are possibilities.


just a thought, and just for my own curiosity.


Brian


----------



## Ethan Winer

Brian,


> if you don't mind emailing the files (i'm sure they are huge) i'll take an hour and try to process them on some equipment here at the lab. ASCII files or .wav files, if they are possibilities.


----------



## Brian Ravnaas




> Quote:
> _Originally posted by Ethan Winer_
> *Brian,
> 
> 
> The 13 files I have are native ETF data files, and each is about 790 KB. If you have ETF I'll be glad to send them to you so you can do whatever analysis you'd like. But if you don't have ETF these files will be of no use.
> 
> 
> --Ethan*



i've got no ETF, so i guess for now i can't do anything.


Brian


----------



## strange_brew

I have been reading through this thread and although I have gleaned a ton of great information, I don't think this question ever got answered definitively (pg.3 of the thread). I have seen one response saying it doesn't matter if you treat above ear level at all (its only for aesthetics) and another which says it is part of the sound characteristics of the room. Which is it? I would love to just paint that part of it and be done.



> Quote:
> _Originally posted by smithb_
> 
> I really could you use some advice based on the following questions:
> 
> 
> -----------------------------------------------------------------------------------------
> 
> I am very interested in an answer to "gjlowe" question:
> 
> 
> "if you put a ledge molding instead of chair rail around the walls, do you even need treatment on the upper half?"
> 
> 
> My plan is to treat the whole lower half (ear level and below) of the room as suggested (except full treatment on front wall). However, I have read mix messges on the value of using cloth covered batting on the top. Some say it is for acoustical purposes and some say that it just pushes the upper wall out to meet the treatments of the bottom half. I personally would like to just paint the top half and build a ledge in the chair rail to save money if batting doesn't add any additional value. So which is it?
> 
> 
> What is the rule about hanging pictures on the upper walls?
> 
> 
> Some treat the lower half of columns and others do not. Is there a reason to go one way or the other?
> 
> 
> I see many putting heavy curtains along the front wall which looks very nice. What impacts does this cause on the front wall treatment? No impact or cancel it out?
> 
> 
> Finally, do people treat the wall area behind the screen?
> 
> 
> Thanks for any feedback.
> 
> -----------------------------------------------------------------------------------------
> 
> 
> Any response from the experts would certainly be appreciated: Dennis or Eric?


----------



## Terry Montlick

strange_brew,


Batting is definitely not just for aesthetics. It provides significant sound absorption.


Whether or not you need it depends on your room. There is no "one size fits all" in room acoustics.


For example, suppose your front speakers are mounted high up, and the first reflection points between speakers and ear are above the level of the fiberglass treatment. Then you definitely want to put up polyester batting (or additional fiberglass) to absorb these reflections.


On the other hand, if the fiberglass itself provides the right amount of absorption for correct reverberation times, adding batting may over-absorb high frequencies.


The only way to know is to test and/or computer model your room.


Regards,

Terry


----------



## strange_brew

Thanks Terry.


Then I'm guessing that in most cases it must be required from the number of theaters (particularly DE designs) that include it. I suppose that answers another of the questions that has been bothering me as well - when I look at many of the professionally designed theaters (again, mostly DE designs), it looks to me like the lower "insulshield" portion is lower than ear level? Or maybe its just hard to tell from the screenshots I have seen.


To be honest I glossed over much of the thread that dealt with computer modelling the rooms since what I gathered (particularly from Dennis' posts) is that it just depends too much on people, furniture etc... as those things become a large portion of the volume of the room. And I don't know that i'm up for trying to Ray Trace my room. Obviously this is where the value of hiring a pro designer comes in, but if by mimicking rooms similar to mine I can get 80% of the way there, I'll probably be happy.


Craig.


----------



## Ethan Winer

Craig,


> I have seen one response saying it doesn't matter if you treat above ear level at all


----------



## strange_brew

Thanks Ethan. I think I'll follow the crowd on this one and go with the Polyester batting and GOM.


----------



## kg2kg

Hello,


I have been reading and learning a lot. Thank you very much for all your time you put into this.


Here are two pictures of my dedicated home theater that is in the beginnings of construction by me. I am interested in your thoughts about my design? I have some options right now while under construction.


1) Most dedicated home theaters I see pictures of have the front speakers close to the screen. Am I making this more difficult by trying to have the speakers far forward for an equilateral triangle? Complicates #2 below.


2) As it stands now, I would have to go behind the speaker to access the equipment. AV equipment can be moved toward the screen more and not have a corner trap. Or back and then move the speaker toward the screen. Thoughts on this.


3) Are the rear surrounds placed in the room properly with the door and walkway to the seating? Door can be moved only back. If I move it back further is there any advantage?


To answer these questions more fully, I know you will need the RT60 and the sound adjustment ideas. I am working on the RT60 calculation and so far it looks like this:


Preliminary results from Chris Whealy's 2004__V 2.61


1.5? Ductboard with Foil facing NRC =.90

Frequency___________125Hz___________250Hz___________500Hz___ ________1KHz___________2KHz___________4KHz

Sabine_______ _ _ _ _ ___0.43___________ __0.43__________ _ _ 0.27______ _ _ _____0.21__ _________0.23________ ___0.21

_

1? Ductboard with Matt facing NRC =.70

Frequency___________125Hz___________250Hz___________500Hz___ ________1KHz___________2KHz___________4KHz

Sabine___________ _ _ _ _0.45___________ _ _0.56___________ _ 0.36_______ _ _ ____0.26___________0.23_________ ___0.21


Room details:

I currently have the 1.5" and 1" ductboard.

Room size 88.25" H x 139.75" W x 235"L (in basement). Room Volume 1,677 ft3

Fabric covered Insulation on Lower 48? side wall coverage and entire front wall

Upper side walls and back is painted

Ceiling and walls are basic 1/2" drywall, no insulation in Ceiling, walls have R-13 in standard wood studs.

Carpet is a shag with a 1/2" pad over concrete

Seating is one large cloth pillow back sofa 110" x 36" (4 seats) plus two ottomans (18" x 31")

Door is a can be either hollow or solid core?

AV equipment will have a glass door over the front of it (approximately 60" x 18")

Screen is 96" wide and is Gatorfoam painted.

Projector AE700, ceiling mounted


Thanks for your help,


Kevin

 

top down view.pdf 23.6708984375k . file


----------



## kg2kg

Here is the speaker firing diagrams to go along with the top down view in previous post.


Thanks, Kevin


----------



## Toeside

Question regarding OC703 on my front wall.


My plans include covering the front wall with OC703. I'll have a false wall about 30" out from that covered in black GOM FR701 fabric. My L/C/R speakers and my sub will be behind this false wall. My RPTV will be recessed into this false wall.


Should I cover the OC 703 on the wall to keep the fiberglass from possibly becoming airbourne inside this false wall area? I've never seen OC703, so I don't know if this is a valid concern or not.


----------



## ChrisWiggles

It's fairly well-contained as far as fiberglass goes, fluffy insulation seems to let loose a lot more fibers, it seems that the fiberboard tends to release fibers mainly with physical contact, so you should still wear gloves. I have an MD in the family, so I definitely made sure to cover all the fiberglass to keep from breathing it in, but if you have a false wall covered in fabric, I think that barrier is relatively effective for that unless there is a lot of air blowing around in there.


I'm really not qualified to know, but my common sense tells me that you'd at least avoid having bare fiberglass in areas where people are, or where there are air vents and such.


----------



## BasementBob

I haven't tried 703 nor linacoustic, but with Roxul's rigid rockwool I found that when I carried some around with my bare hands that eventually my hands started to feel prickly and turned red. Nevertheless I'd say the effect was much less than I've had on exposed arms (holes in workshirt near buttons at wrists) and neck when I've worked with fluffy insulation insulating a house and attic. Also some little pieces (1/4") and dust fell off when the Roxul panels were moved or bumped. Thereafter I handled it with rubber gloves and a jumpsuit.


----------



## LarryChanin




> Quote:
> _Originally posted by Toeside_
> *Question regarding OC703 on my front wall.
> 
> 
> My plans include covering the front wall with OC703. I'll have a false wall about 30" out from that covered in black GOM FR701 fabric. My L/C/R speakers and my sub will be behind this false wall. My RPTV will be recessed into this false wall.
> 
> 
> Should I cover the OC 703 on the wall to keep the fiberglass from possibly becoming airbourne inside this false wall area? I've never seen OC703, so I don't know if this is a valid concern or not.*



Hi,


I used coated Insulshield behind my fabric false wall and I've never experienced any problems with airborne fiberglass. As Chris cautions, there were no air vents behind the false wall.


Larry


----------



## Toeside

I don't have any vents where my false wall will be, so that's not a concern.


However, I am concerned with the air movement caused by the sub that will be behind the fabric wall.


I think I'll try to find insulshield locally (there's a place to get OC703). If I go the OC703 route, maybe I'll cover it with fabric to be safe.


----------



## LarryChanin




> Quote:
> _Originally posted by Toeside_
> *I don't have any vents where my false wall will be, so that's not a concern.
> 
> 
> However, I am concerned with the air movement caused by the sub that will be behind the fabric wall.
> 
> 
> I think I'll try to find insulshield locally (there's a place to get OC703). If I go the OC703 route, maybe I'll cover it with fabric to be safe.*



Hi,


I've got a decent size subwoofer and full range main speakers behind the fabric false wall, and still no problems.


Larry


----------



## Erikb

From this thread, it seems that curtains can help with high frequencies, but not really low frequencies. In my case, I plan to put a large front projector screen in front of an even larger set of picture windows. I could pull thick drapes across when using the room, but would the windows still severely damage the sound quality?


Is there anything I could do with other materials, while still having the option of seeing out the windows when I wasn't using the projector?


What about the idea of angling the windows a bit so that the reflections go to the sides instead of straight back to the viewer/listener?


----------



## Terry Montlick




> Quote:
> _Originally posted by Erikb_
> *From this thread, it seems that curtains can help with high frequencies, but not really low frequencies. In my case, I plan to put a large front projector screen in front of an even larger set of picture windows. I could pull thick drapes across when using the room, but would the windows still severely damage the sound quality?*



Cheap, wimpy curtains won't do much. But heavy velour drapes of 18 ounces per square yard, hung in loose folds, provide pretty good sound absorption:


absorption coefficients (from L.L. Beranek's "Acoustics")

0.14 at 125 hz

0.35 at 250 hz

0.55 at 500 hz

0.75 at 1000 hz

0.70 at 2000 hz

0.60 at 4000 hz


Theatrical supply houses stock this really heavy material. I use Georgia Stage -- www.gastage.com. 


- Terry


----------



## Erikb

Thanks, Terry. That was exactly what I was looking for.


Your reply also led me to find this book:


Noise and Vibration Control Engineering : Principles and Applications

by Leo L. Beranek


which has some great additional information (found using the "search inside this book" feature at Amazon).


----------



## craig john

I have ordered some 1" OC 705 for my front wall. I will have enough to put some behind my screen, (92" Da-Lite HCCV, non-perforated). The screen is mounted 3" off the wall, so I could get some in there, but is it even worth doing if the screen is non-perf'd?


Also, what is the recommended mounting method for OC 705? It will be covered by burgundy velvet drapes, so it won't be seen.


Thanks,


Craig


----------



## Terry Montlick




> Quote:
> _Originally posted by craig john_
> *I have ordered some 1" OC 705 for my front wall. I will have enough to put some behind my screen, (92" Da-Lite HCCV, non-perforated). The screen is mounted 3" off the wall, so I could get some in there, but is it even worth doing if the screen is non-perf'd?*



Hi Craig,


If the screen is not micro-perforated, then it's not worth putting fiberglass behind. The solid screen would reflect frequencies above a few hundred hertz. But below this frequency, the absorption ability of even 3 inches of fiberglass falls off significantly. So you'd end up with an absorber peaking at a few hundred hertz.


- Terry


----------



## LarryChanin




> Quote:
> _Originally posted by Terry Montlick_
> *If the screen is not micro-perforated, then it's not worth putting fiberglass behind. The solid screen would reflect frequencies above a few hundred hertz. But below this frequency, the absorption ability of even 3 inches of fiberglass falls off significantly. So you'd end up with an absorber peaking at a few hundred hertz.
> *



Hi Terry,


What about a non-perforated screen that is 24" off of the wall?


I have my screen mounted across a recess that is 24" deep. There is 18" of space over and 22" of space under the screen for sound to get behind it.

Plan View 

Front View 


I have 1" of Insulshield covering the entire front wall, including the insides of the recess. I would like to add more insulation to improve the bass response, but I feared that it might make the room too dead at the mid and higher frequencies. I've attached a graph the Reverberation Time of the room, which you can see is fairly low.


However, I had not considered that the screen might reflect most of the mid and high frequencies traveling to the recess. Do you think adding 2-3 more inches of insulation in the recess behind the screen might make the room too dead. The recess is roughly 7' wide by 9' high. The room is 15' wide x 26' long (including the recess) x 10' high.


Thanks.


Larry


----------



## Terry Montlick




> Quote:
> _Originally posted by LarryChanin_
> *I would like to add more insulation to improve the bass response, but I feared that it might make the room too dead at the mid and higher frequencies. I've attached a graph the Reverberation Time of the room, which you can see is fairly low.
> 
> 
> However, I had not considered that the screen might reflect most of the mid and high frequencies traveling to the recess. Do you think adding 2-3 more inches of insulation in the recess behind the screen might make the room too dead.*



It would be fine, Larry. It should only affect the low frequencies, because your screen is already reflecting the highs.


- Terry


----------



## krasmuzik

Terry


Have you done the calculation of vinyl movie screen (nonperf) over fiberglass as a membrane bass trap? One of the things on my list of things to do.


----------



## HuskerHarley

Will the spray glue on the GOM and 703 wreck any of the acoustic capabilities of either?


Is it necessary to glue the two together?


I was hopping to be able to just use staples but I've read that most seem to spray glue on both materials and I am concerned that it might cause a reflection instead of absorption????



Husker


----------



## mendes9

Well.. I finally picked up some OC 703, and I'm still waiting on my GOM fabric samples.. so I can't make my panels and bass traps yet.. but for the heck of it, I decided to place some on the wall and behind my screen anyway... Now I wish I could do a simple A/B, panels off panels on quickly ... but with DVD's I'm very familiar with I noted the following...


1. Significant dialouge improvement from center channel (B&W Matrix HTM), I had to turn the level down 2 levels (had it +3 compared to front channels)


2. Surround speakers much more defined, and localized. Example, when listening to Bugs life.. I heard the ambient rear surround channels much more distincly..


3. The room just sounds much more dead... don't know how else to say it, it's just not alive as it used to be...


I haven't done a frequency response comparison of the room yet... I only use test tones and Rat Shack SPL meter...


Overall, the sound is just more defined, and I can better tell from what speaker the sound is coming from.. I woudl say that's the biggest difference. I couldn't play anything too loud to tell any bass differences...


----------



## Terry Montlick




> Quote:
> _Originally posted by krasmuzik_
> *
> 
> Have you done the calculation of vinyl movie screen (nonperf) over fiberglass as a membrane bass trap? One of the things on my list of things to do.*



I'm not sure that this would be a good idea.


For one thing, you'd have to seal your screen to a box. Also, the very low frequency absorption wouldn't be great because of the hole size and hole/area ratio of the screen.


Having said that, here is the predicted 0-incidence response (transfer matrix method) of a 0.4 mm thick Stewart microperf screen covering a 1-foot deep box completely filled with uncompressed fiberglass batt.



















Not a bad broad-band absorber, though I wouldn't call it a bass trap.


- Terry


----------



## HuskerHarley




> Quote:
> _Originally posted by HuskerHarley_
> *Will the spray glue on the GOM and 703 wreck any of the acoustic capabilities of either?
> 
> 
> Is it necessary to glue the two together?
> 
> 
> I was hopping to be able to just use staples but I've read that most seem to spray glue on both materials and I am concerned that it might cause a reflection instead of absorption????
> 
> 
> 
> Husker*




Please...










Husker


----------



## Terry Montlick




> Quote:
> _Originally posted by HuskerHarley_
> *Will the spray glue on the GOM and 703 wreck any of the acoustic capabilities of either?
> 
> 
> Is it necessary to glue the two together?
> 
> 
> I was hopping to be able to just use staples but I've read that most seem to spray glue on both materials and I am concerned that it might cause a reflection instead of absorption????
> 
> 
> 
> Husker*



A thick enough layer of spray glue could create some high frequency reflection. I'd avoid glue if possible, or confine it to the edges.


----------



## LarryChanin




> Quote:
> _Originally posted by Terry Montlick_
> 
> 
> quote:
> 
> --------------------------------------------------------------------------------
> 
> Originally posted by krasmuzik
> 
> 
> Have you done the calculation of vinyl movie screen (nonperf) over fiberglass as a membrane bass trap? One of the things on my list of things to do.
> 
> --------------------------------------------------------------------------------
> 
> *I'm not sure that this would be a good idea.
> 
> 
> For one thing, you'd have to seal your screen to a box. Also, the very low frequency absorption wouldn't be great because of the hole size and hole/area ratio of the screen.
> 
> 
> Having said that, here is the predicted 0-incidence response (transfer matrix method) of a 0.4 mm thick Stewart microperf screen covering a 1-foot deep box completely filled with uncompressed fiberglass batt.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Not a bad broad-band absorber, though I wouldn't call it a bass trap.
> 
> 
> - Terry*



Hi Terry,


Kevin's question was in regard to a non-perforated screen.


Neverthess, very interesting information.


Thanks.


Larry


----------



## Terry Montlick

krasmuzik,


Sorry, I misread your posting. You asked about a non-perforated screen. I'll do the calculations for this, and get back to you.


- Terry


----------



## Terry Montlick

Here it is.


Identical to the earlier device I posted, but the screen does not have the perforations.


- Terry


----------



## mooney

JM INSUL-SHIELD question.


Trying to buy and must buy a "unit" ie 48 pieces regardless of size. (I will use 2x4)


I assume I need the" knitted faced" but they come in densities ranging from 1.5 to 6.0 lbs/sq ft.


Which density do I need for lower 48 inch side walls and complete front wall? The theater is 12x20x9 ft.


Yes I have read the entire thread but after 18 months of house building I am in overload.


----------



## Ethan Winer

Bob,


> Which density do I need


----------



## mooney

Density


Is the spec 3 lbs/cubic ft OR 3lbs/square foot as my supplier told me. Big difference ie 2x4=8 sqft x 3 = 24 lbs for one sheet. ??


Anyone using a different density?


----------



## bpape

3 lb/cu ft. If it were by the SQ FT, then you'd have different ratings for different thicknesses (1", 2", 4", etc.)


Some people use 6lb for bass trapping purposes. 3lb is a more genral purpose, all around good density for bass absorbtion, reflection points, etc.


----------



## mooney

bpape


OK then I should use 3 lb/cuft for entire front wall and lower 4' of both side walls?


----------



## mendes9

mooney,


I put 1" OC 703, on my front wall ( behind my screen and velvet curtains), and put 1" OC 703 at my reflection points. I didn't put anything upto ear level, since I'm not doing the room from scratch, so only the reflection points. I'm doing these treatments after the fact.


Intially, I had only treated my reflection points, and I really liked the difference, as I posted above. This weekend, after also treating my wall behind my screen ( 1" OC 703 beghind screen and light duty velvet curtatins), I don't know.. I'm having 2nd thoughts, I have to try it without because it may be too dead.. Maybe the light duty velvet curtains were enough.. and for me the refletion points will suffice.. I just hate to take it all down again...







to see what it sounds like without an treatment on my front wall....


----------



## jschmidt

First, let me apologize for my ignorance. I have tried to read this thread along with a bunch of articles on the web such as Audioholics, etc. I am trying to figure out how to acoustically treat my new home theater. I'm not stupid, honestly, but for some reason I just can't seem to figure out all this acoustical business. My new home theater is fairly big: 26x15x8. I don't have the furniture in yet, but it will be leather, which won't help acoustics much. I would like to improve the acoustics of the room for use with multi-channel sound.


My questions/concerns:


1. Can someone point me to a source that can help a beginner out with what is needed from a practical standpoint? I find the science/physics of sound interesting, but I don't really get it. I need a source of practical how-to information on how to treat the room. I need information on placement of panels, number of panels, reflection points, bass traps, materials, etc. In the end, all I want is to have a great-sounding theater.


2. I would prefer not to cover the entire surface of every wall. I have sconces already installed so that may also pose an obstacle. Further, I want to make sure that whatever is installed is aesthetically pleasing.


3. I don't want to spend thousands of dollars. Are there places out there that sell completed panels/bass traps at a reasonable price? I am willing to do some work myself to make them, but I am confused by all the different terminology and materials discussed.


Any help is appreciated!


Thanks,


Jonathan Schmidt


----------



## krasmuzik

jschmidt


contact homeacoustics.net to find an audio calibrator in your area. They know the science and are familiar with treatment solutions.


----------



## jschmidt

Thanks, Krasmuzik. The nearest engineer is about an hour and a half away. (I live in a rural area.) I'll give him a call, but I'm worried about the cost of hiring someone like that. But, I suppose if I want it done right, I'll need the help.


If anyone else has any other suggestions, I would appreciate it.


----------



## Ethan Winer

Jonathan,


> it will be leather, which won't help acoustics much.


----------



## krasmuzik

jschmidt


HAA is to Audio techs much like ISF is to Video techs. They are not expensive acoustic engineers - they just have been trained on acoustic science so they stay away from audiophile voodoo that some AV places participate in. So they should give you bang for the buck solutions - maybe even just moving stuff around the room, or a list of things to get at industrial warehouses.. Most calibrators realize their market is limited to how far they can travel - I just did a three hour trip last weekend!


Of course there are several acoustic engineers and acoustic treatment companies that hang out in this thread who would be willing to help you.


----------



## jschmidt

Well, I got the estimate back from the place I was referred to by HAA. I'm not a good judge of whether ehtier pricing is reasonable, but it is definitely a LOT more than I was thinking. To start, they recommended the following:


* Seating and speaker placement modelling - $695

* Modelling of first order reflection points - $695

* Modelling of reverberation control (where to put the accoustical treatment and what size) - $1500


Mind you that this does not include any on-site visit. I would have to provide them with all measurements of the room. This also does not provide any actual accoustical treatment. Only provides a mapping of where the speakers and seats need to go along with a diagram of where the accoustical treatment needs to be applied.


I don't know about you guys, but spending nearly $3000 for no actual sound improvement to the room is not my idea of value.


Thanks, Ethan for the very informative article! When it comes to actually putting up some accoustical treatment, I will get some OC from my local HVAC company. I have a call into them to see if they can special order from 705-FRK. It's not something that they normally use for ducts. Instead, they typically use Enduragold, which does not appear to have the accoustical properties needed. Your article helped a ton!


Now I just need to find a cheaper way to figure out the first order reflection points to at least make sure those are covered... without spending $3000.


----------



## Terry Montlick




> Quote:
> _Originally posted by jschmidt_
> *
> 
> ...
> 
> Now I just need to find a cheaper way to figure out the first order reflection points to at least make sure those are covered... without spending $3000.*



That's pretty easy, unless somebody wants to sell you a $3000 mirror.







All you need is one other person and a mirror. Do a search on the forum - their are a number of discussions on the mirror method for finding the first reflection points.


- Terry


----------



## Ethan Winer

Jonathan,



> Quote:
> * Seating and speaker placement modelling - $695
> 
> * Modelling of first order reflection points - $695
> 
> * Modelling of reverberation control (where to put the accoustical treatment and what size) - $1500
> 
> 
> Mind you that this does not include any on-site visit.



Yikes, you can get all that for free on the Articles page of my company's web site!


--Ethan


----------



## nirvana_av

For $3K you could buy a boat-load of Ethan's traps.


----------



## krasmuzik

All this depends if you value your money more than your time. Everyone on here is always happy to educate - but you have to be willing to make the investment in time to learn. If you consider that calibration is normally charged at a higher rate than the guys pulling the wire - say $100/hr instead of $75/hr -their fees are not that unreasonable considering contractor overhead is usually 3x take-home pay. It probably takes half the time quoted - but you have to leave room for the back and forth on the design and multiple redos. You could look into Dennis and Terry on this forum to find out what they charge for design/calibration as they both work nationally.


* Seating and speaker placement modelling (1 day)


Good resources for this are Harman Kardon white papers, RPG Room Sizer/Optimizer, and CARA. To be most effective you will need to know the directivity and crossover data for your drivers.


* Modelling of first order reflection points (1 day)


Two people and a mirror, as already suggested. Don't forget to check all reflective surfaces - any soffits, ceilings, floors, stages, proscenium, columns, etc. This needs done in every seat for every front speaker. RPG Room Optimizer will do this for a rectangular room. You also need to know how much reflection to cut, and how much to keep (how deep - how long - how wide - in space and time)


* Modelling of reverberation control (where to put the accoustical treatment and what size) (2 days)


Here is where it gets difficult. You have to know the frequency absorption curves of your material and how much total to use in the room, to achieve what reverb time. Absorption varies depending on how much the edges are exposed and how far it is from the wall. SpreadSheets or CARA are useful tools for this.


BasementBob has been an avid collector of absorption data - his website is a good start. Don't forget that your carpet, chairs, risers, walls, stage, etc. all have variant absorption curves, as well as people.



Finally, what you were not quoted was calibration& verification of the design. This involves taking impulse or sweep measurements of the room. ETF5 is a popular program for this - mostly because it is free, unless you expect to save your work for later analysis or use a calibrated mike/preamp, or use useful special features.


What the HAA tech should have told you is they have a 50pt design checklist they can use on your room - this is always a good start with a site visit or floorplan review, and should be done for a much more nominal fee. If you have some fatal flaws in your room - you may want to fix those before pursuing treatment.


----------



## Terry Montlick




> Quote:
> _Originally posted by krasmuzik_
> *You could look into Dennis and Terry on this forum to find out what they charge for design/calibration as they both work nationally.
> *



I currently charge $95/hr for everything - acoustical device design, custom theater design, measurement, calibration, computer simulation from 3D DXF files using professional ray-tracing software, etc. Also 1/2 that rate for actual travel time. And of course, there's the Great Food Discount if you live in someplace like New Orleans.










- Terry


----------



## Dennis Erskine

...I charge extra for New Orleans. That way I have more to spend on food.


----------



## Terry Montlick




> Quote:
> _Originally posted by Dennis Erskine_
> *...I charge extra for New Orleans. That way I have more to spend on food.
> 
> 
> 
> 
> 
> 
> 
> *



Okay, we can buy each other oysters at the Acme Oyster House.










Regards,

Terry


----------



## kromkamp

For what its worth, I tried to engage every single listed HAA contractor in the Southern Ontario area to do room measurements, treatment suggestion and followup and every single one denied me. They all wanted to only handle turnkey HT setups (ie. designing & building the entire space from scratch).


I dont know if this is typical of all HAA certified contractors.


Andy K.


----------



## krasmuzik

kromkamp


I think that is typical of most CEDIA contractors, which tend to ignore the DIY marketplace. ISF indicates if calibrations are available with installations only or if calibrator is independent. Sounds like something HAA should do as well!


----------



## mikemav

 www.rivesaudio.com 

They have packages from basic planning for DIY up to full design & CAD work and after-install calibration/tweaking. They do not sell treatments, so they show how to DIY home build them in the sample drawings I saw. The pro-AV company I work for has signed on as a local delaer so we can use their services for commerical installations where acoustic treatment and/or sound control isolation planning are needed, but their bread and butter is 2-channel high end rooms and home theater. I was referred by Dennis since he was at the time also only doing turnkey design of the full system (that may still be the case; not sure.) Being an AV designer myself, I did not need the system wiring and site planning help, only the acoustic modeling and tweaking. If I can ever find a contractor to build out my room, I am going to become a Rives customer as well. The way it works, the local dealer has a test kit to come out and measure the room before and after. That data, along with answers about the room, aesthitcs, and system equipment is sent to Rives designers, who generate the plans for a DIYer or GC to build. Then after the room is built to plans and the treatments added, the room is measured again and any necessary tweaks are suggested.


PM me if you are in the DC area and are interested in learning more. As I said, my employer does not install home theater, but we can probably do the measurements for a Rives design sale locally.


----------



## Terry Montlick




> Quote:
> _Originally posted by mikemav_
> * www.rivesaudio.com
> 
> They have packages from basic planning for DIY up to full design & CAD work and after-install calibration/tweaking. They do not sell treatments, so they show how to DIY home build them in the sample drawings I saw. The pro-AV company I work for has signed on as a local delaer so we can use their services for commerical installations where acoustic treatment and/or sound control isolation planning are needed, but their bread and butter is 2-channel high end rooms and home theater. I was referred by Dennis since he was at the time also only doing turnkey design of the full system (that may still be the case; not sure.) Being an AV designer myself, I did not need the system wiring and site planning help, only the acoustic modeling and tweaking. If I can ever find a contractor to build out my room, I am going to become a Rives customer as well. The way it works, the local dealer has a test kit to come out and measure the room before and after. That data, along with answers about the room, aesthitcs, and system equipment is sent to Rives designers, who generate the plans for a DIYer or GC to build. Then after the room is built to plans and the treatments added, the room is measured again and any necessary tweaks are suggested.
> 
> 
> PM me if you are in the DC area and are interested in learning more. As I said, my employer does not install home thester, but we can probably do the measurements for a Rives design sale locally.*



Any existing Rives dealer is also eligible to become an Alpha Certification Representative, if they're good enough







. We can utilize the data from their test kit as well. We analyze it using our own proprietary software, and can award certification if the room meets our strict acoustical standards. We provide a detailed 6-page acoustical report on the room, which includes early reflection analysis, reverberation times, and dialog quality including Speech Transmission Index. We do all this for $299.


In addition to analysis and certification, we also offer all the design services that Rives does. We can do *very* advanced acoustical analysis and modeling (including the same professional quality ray-tracing as is done for concert halls), plus complete HT design, all for very reasonable prices. Our complete custom design and acoustical evaluation packages range in price from $395 to $1595. We give you CAD plans for use by DIYers or professional builders.


Regards,

Terry


----------



## kromkamp

I agree. I've heard good things about Rives but for my money, I would prefer to support someone like Terry who hangs around here and gives away so much free advice.


And I probably will enlist Terry's services at some point in terms of remote analysis. However it would be nice to have local options too.


----------



## jschmidt

Okay, thanks for the help everyone so far. I have a few more questions that I was hoping to get some more help with.


After thinking things through, I think I will probably try to make some treatments myself to save some dough. Thanks for all the advice and links!


One problem I am having is locating a place to buy OC rigid fiberglass. Based on the info provided here, I would like to try OC 705-FRK in 1" and 2" to make different styles of treatments. I have contacted several HVAC places and no one seems to use it. The closest I have found is a place that uses EnDuraGold. It is an FRK-type board, but the accoustical properties on OC's web site are much lower than 705. Any ideas on how I can get my hands on a box or two of 705?


Second, I'm trying to find fabric. I have been to two different local fabric stores, but can't really find anything suitable. Can anyone offer suggestions of places to find good material to use to cover the treatments?


Thanks,


Jon


----------



## dsinder

For fabric: http://www.silentsource.com/gom_index.html


----------



## Ethan Winer

Jon,


> One problem I am having is locating a place to buy OC rigid fiberglass.


----------



## Dennis Erskine




> Quote:
> If I can ever find a contractor to build out my room, I am going to become a Rives customer as well.



Our Certified Home Theater Builder program will be rolling out shortly ... once a NARI member is certified by us to build acoustic spaces, dealers and home owners will be able to seek out builders that have been specifically trained to build these special purpose rooms. Starting at CEDIA EXPO, those individuals who've met the training and experience requirements can sit for the Home Theater Designer exam. The Master Designer practical exam (a two day exam) will not be "in the can" for a few more months.


----------



## Terry Montlick




> Quote:
> _Originally posted by Dennis Erskine_
> *Our Certified Home Theater Builder program will be rolling out shortly ... once a NARI member is certified by us to build acoustic spaces, dealers and home owners will be able to seek out builders that have been specifically trained to build these special purpose rooms. Starting at CEDIA EXPO, those individuals who've met the training and experience requirements can sit for the Home Theater Designer exam. The Master Designer practical exam (a two day exam) will not be "in the can" for a few more months.*



This sounds like a much-needed program for the industry. In addition to the mystery of sound isolation construction, contractors typically have no experience with stretch fabric (GOM etc.) installation. I hope you are making this a significant part of the curriculum. Track-based fabric installation is extremely important, in addition to the easier "cover the edges with trim" method that is possible for some but not all room designs.


Regards,

Terry


----------



## krasmuzik

Dennis


Is this Design Cinema Privee certification or are you talking about CEDIA Home Theater Designer certification. Will there be a CEDIA Home Theater Installer certification (for fabric, stage, riser construction techniques)?


BTW can you PM me who to bug about updating CEU records - I sent to the generic mail on the web page with no response. Really reluctant to spend more money on training if I am not getting credited!


----------



## cinemascope




> Quote:
> _Originally posted by kromkamp_
> *For what its worth, I tried to engage every single listed HAA contractor in the Southern Ontario area to do room measurements, treatment suggestion and followup and every single one denied me. They all wanted to only handle turnkey HT setups (ie. designing & building the entire space from scratch).
> 
> 
> I dont know if this is typical of all HAA certified contractors.
> 
> 
> Andy K.*



This is fairy typical in my market as well.


IMO, there are DIYs, and then there are strokes... and DIYs are always welcome to call me.


I also specialize in turnkey HT and multi-room audio systems, but I always return calls from DIYs seeking assistance and guidance and I give everyone the benefit of the doubt. I would much rather deal with an upfront person that is honest about their intentions to do the work themselves rather than a stroke who is leading me on under the guise of getting a job bid, with every intention to sponge up some info and go e-shopping for all the gear.


With all the tremendous resources like this that allow anyone to research on their own, I feel pretty insulted when someone wants me to design their systems for them for free.


Everyone wants a fair price, and many here also want the satisfaction of building a portion of their dream system, but I get turned off by guys that lead me on... We have to make money at what we do for a living just like everyone else in the world.


I have also been known to come over and lay eyes on the project in question even if we are not able to get involved in any way because of scheduling issues, etc. If I meet someone who is building an ambitious project that wants do do a lot of it themselves, I would rather help them out if I have the time rather than snub them. Maybe I only provide a small piece of the overall project, or even nothing at all.


Who knows, someday I may get a referral from a less mechanically inclined friend of a DIY person I helped out, rather than have a snob reputation and force his friends go to the big box places and get bad advice and wind up with mediocrity.


We even hired a guy that we met as a DIY guy when he was shopping for a projector we carried. He worked for a retail a/v store, and was/is an avid enthusiast and AVS lurker. He now works for a competitor, but we have a lot of respect for him and his new employer, that's just the way it worked out.


As I said, I have been known to provide tons of advice and resources for the very low, low price of free... HT has been pretty good to me over the years, and I don't mind spending some spare time speaking with enthusiasts or contributing at places like this.


Andy,

I am in the Chicago area, but I will likely be visiting Toronto the first weekend in June to take the CEDIA Designer I exam I have been putting off. If you are interested at all, I could bring my laptop and mics with me and stop over. PM me if you are interested in discussing this.


----------



## cinemascope




> Quote:
> _Originally posted by Dennis Erskine_
> 
> Our Certified Home Theater Builder program will be rolling out shortly ... once a NARI member is certified by us to build acoustic spaces, dealers and home owners will be able to seek out builders that have been specifically trained to build these special purpose rooms.



Are you speaking of NARI remodeling contractors??


This is a good idea, but the dealers we deal with every day sure are hesitant to listen to us "audio guys" when it comes to building methods.


What has your experience been with relaying advice/recommendations to builders and actually having them follow it??

In the time I take explaining WHY I want linear diffusors and staggered stud walls with USG acoustic sealant applied to the sole plate/wallboard seams to the manufacturer's specs, I could probably construct the rooms myself.


The electricians are cool with us, and when we specify dedicated circuits, specific light fixtures, home run wiring for Grafik Eye or HWI panels, etc. they understand that there are legit reasons.


On the other hand, the builders think we are nuts, and that the isolation/noise control methods we advocate are overkill, and that we are simply blowing the clients' budget.


> Quote:
> Starting at CEDIA EXPO, those individuals who've met the training and experience requirements can sit for the Home Theater Designer exam. The Master Designer practical exam (a two day exam) will not be "in the can" for a few more months.



I hope you are not planning to actively invite builders to come to CEDIA, the old timer integrators will lynch you. As an integrator who has been a member of CEDIA since the early days, I do not want the suppliers that display on the floor to mistakenly solicit builders standing before them at a TRADE show when they are not a part of our trade.


I am interested in acquiring the Home Theater Designer Certification and/or Designer II Cert. as soon as they are available. Do you expect DII to be available by Expo??


Thanks,

Rick


----------



## Dennis Erskine

Kras.... contact Scott McCormack at CEDIA.


The Home Theater Designer and Master Designer are CEDIA certifications and will be challenges.


The Home Theater Builder will not be a CEDIA course but rather one I am working on outside of CEDIA.


The Home Theater Designer Exam will be ready by Expo and those with Designer Certification will be provided the announcement in advance of CEDIA. The Exam is rigorous and will require a broad base of knowledge to pass. The Master exam will not be ready this year and is a practical exam (which is why it is taking soooo long to prepare).


Yes, NARI is the remodelers organization. In general, we've found builders to be receptive and by and large follow our direction EXCEPT ...

The exception has been home builders that build on spec. They, as a general group, once they find out what needs to be done, don't care to do so since the additional expense is not part of their original budget and they have no certainty the future homeowner would even want such a room. But, where a homeowner is involved and willing to pay for the additional expense, they are all ears.


We have had a couple of cases where the builder didn't follow our instructions and took shortcuts (without consulting us or the client). In those two cases, the builder (at the builder's expense) had to rip out the work and start over.


----------



## cinemascope

Good morning Dennis!!


Sorry I was editing my post as you posted...


Thanks for the reply, and I am relieved to hear that the builders' spec is outside of our trade organization.


Best of luck with this, and if you need any more participants to provide field perspective to the process, I am rarely at a loss for words and would be happy to contribute. Feel free to PM me to discuss.


----------



## cinemascope

I had to pull a Sony 400 disc changer recently and replace it with a Pioneer 300 disc just to save a couple inches of depth in a whole house music rack on a modest job where the client didn't want to give up a closet for us.


I gave the GC and the lead carpenter of a CUSTOM builder that we work for a rack tools drawing of the AXS rack that was going to be used with very large type o the measurements... but they did not accommadate me on the dimension change.


Funny thing is, the HVAC guy ran my ventilation run to basement, but opened one of my holes to do it!! I had to move aside insulation and drill a new one in my dress clothes standing on borrowed ladder the day the rockers were there to cover it!!


The reply from the other carpenter regarding the cabinet was that the change orders have to come from the client, not the other subs. It was like a bratty little child saying "you're not my boss, I don't have to listen to you".

It was all I could muster to keep from stuffing him in that cabinet.


I had to switch to a Slim5, lace the wiring on the INSIDE of the rear rails, build and test the rack on a piece of carpet, then lift it and slide it by hand into the cavity shoving it ALL the way against the rear of the carcass and secure it through the bottom blanks w/ a right angle drill/driver.


That will be a service nightmare is anything ever needs attention.


----------



## cinemascope

As a pro, I am excited to see THX, CEDIA, and others taking an active role in promoting acoustics in the advanced Certifications.


I have heard that someone at this year's Expo will feature two identically sized rooms with idential equipment, except the one will be acoustically treated with advanced methods and products to compare to the other totally untreated room.


Dennis, Terry?? Either of you involved in this of have any additional info about this??


----------



## Dennis Erskine

I am involved with this as part of the Acoustics Guild.


----------



## krasmuzik

Thanks Dennis!


I see Theo K. has retired from CEDIA Architecture award participations and is now sponsoring the award. Maybe a HAA/ISF award for best Technical Theater? I hate cringing when I see the awards catalog! Or maybe a Home Theater Designer award once there is a large enough pool of designers - say they have to submit a certification checklist sheet for the theater.


----------



## Terry Montlick




> Quote:
> _Originally posted by krasmuzik_
> *
> 
> ...
> 
> Or maybe a Home Theater Designer award once there is a large enough pool of designers - say they have to submit a certification checklist sheet for the theater.*



Better yet, measured and certified acoustical performance data!


Regards,

Terry


----------



## cinemascope




> Quote:
> _Originally posted by krasmuzik_
> 
> I hate cringing when I see the awards catalog!



Oh man... I just got the notice that we missed the deadline for "best dressed" competition. My partner is super anal about dressing the racks, and we always joke that the top 2 or 3 awards are actually nice, but it tapers off REALLY fast which leads us to believe that not too many people submit.



> Quote:
> Or maybe a Home Theater Designer award once there is a large enough pool of designers



This is a great idea.

I am concerned at how practical this would be. It would likely be a salesmanship/machismo contest unless the details of the client meetings, builder meetings, and designer/decorator meetings are outlined with can and cannot requests and idiosycratic requests from homeowners. The totals would need to be offset somehow to compensate an interference factor.


I'm not a bad designer because a client insists on a screen that is too small because they want the front pillars HERE, flimsy sconce bezels that buzz from LF, or chairs that have super tall back cushions... I do what I can to educate the clients on more appropriate choices to right the wrongs, but ultimately I am just doing what they want a lot of the time.


----------



## krasmuzik

cinemascope,


But I bet Theo and Russ get their way what with their $$$$$ retainers just to decide if they want to take the $$$$$$$ job or not!


I think awards like that should be based on ultimate performance - if it was checklist or metric based - you could get dinged for the high backed chairs. But if that was the only thing wrong compared to the competition that year - maybe you could win.


Still would beat the other stuff in the "spent a ton of money for a lousy sounding washed out video room" categories. Also I bet the high end customer given a target of - "Do you want to be award winning?" would be more likely to give in.


Why do you think Terry is doing his Alpha certification that exceeds THX specs?


----------



## cinemascope




> Quote:
> _Originally posted by Toeside_
> *Question regarding OC703 on my front wall.
> 
> 
> My plans include covering the front wall with OC703. I'll have a false wall about 30" out from that covered in black GOM FR701 fabric. My L/C/R speakers and my sub will be behind this false wall. My RPTV will be recessed into this false wall.
> 
> 
> Should I cover the OC 703 on the wall to keep the fiberglass from possibly becoming airbourne inside this false wall area? I've never seen OC703, so I don't know if this is a valid concern or not.*



I know someone piped in to say that these types of panels rarely "shed" any fibers, but I wanted to re-open this and say that there are specifications for shedding, although they have a different term that escapes me at the moment.


You may still want to cover the panels, because if any portion is guilty of losing fibers, it is the rough cut ends. In place of the pricy GOM in this low visibility application, you can go econo and seek out some upholstery fabric locally that has a similar ANSI/ASTM rating for fire retardancy as the GOM.


Also, the areas where you are using the panels is not entirely important from the perspective of high velocity air hitting the panels. Ductboard is made from the same material, and in a very similar manner to OC-703 panels. These materials are used to construct or line duct runs to achieve serious reductions in noise transmission through the dusctwork without causing issues from airborne fibers.


Since these products have a proven track record of maintaining their integrity when faced with the high velocities inside air ducts, you can rest easy that your panels behind a false wall will not be contributing to the "itch" factor, regardless of the proximity to the HVAC vents..


The only time you have the possibility of itching is when you are cutting and trimming the panels for size, electrical boxes, etc.


I prefer to do this outside or in a garage and immediately shop-vac everything to keep the fibers from being tracked into the house, and most importantly, off of my skin.


Companies like Kinetics that custom fabricate these panels on a production level use a chemical hardening procedure on the all ends that ensures that the ends will not fray or lose fibers, and also the performance ratings of the panels is actually different with the hardened ends.


Also, their mitering, custom radius shaping and upholstery abilities far outweigh my own, I have never been dissapointed in the fit and finish.


----------



## Dennis Erskine

...there is a move afoot, BTW, to have independent audio/video measurements made in rooms submitted to CEDIA for design competitions at EXPO. Several different methods have been discussed but I'll leave it at that for now.


----------



## cinemascope

Wow.


By "independant" you mean a select group of accredited individuals that maintain calibrated mics/systems of particular requirements??


I would get involved a program like that from both sides, submitting rooms as well as independantly measure/verify/certify rooms for other companies for the Expo contests.


----------



## Dennis Erskine

Yes...the measurement would be either by:


1. a non-related competent and trained individual using approved devices; or,

2. a device would be shipped to the site, plugged into the system, run an established scenario capturing the data that would be sent back for analysis (audio and video).


The dealer submitting the room would bear a cost for the testing. Obviously, there's alot of holes which is what we're working through. However, in plan (1) above, the individual doing the measurement would never be allowed to submit his/her own project to avoid any direct or indirect conflicts of interest.


----------



## pajama sam

I'm building a cabinet to house my center channel speaker and form the base of my screen wall. The cabinet has to be movable for access to the screen wall, so it is built of 3/4" ply and 5.2mm ply front with medium bracing. Approx size is 8' wide 2' high and avg. 1' deep with a bowed front. Finished weight will be about 60 lbs.


My question is this: the cabinet has several unused (unopenable) airspaces in it: 2 are approx 7400 cubic inches and one is 5040 cubic inches. I was planning on stuffing these with fiberglass insulation batts. I want to avoid the cabinet resonating. Should I leave the compartments sealed, or add air ports? If so, is there any way to calculate the area of the ports? Can these chambers be used to serve a useful purpose beyond being acoustically inert (I.E. serving as bass traps)?


Thanks in advance for any advice given, I'm already deeply indebted to this forum!


----------



## cinemascope

Although I have included some ideas, I might just skip the idea of creating an trap/absorber from this and laminate a few layers of thin ply together to make a thick and rigid front and then wrap that in curved pieces of acoustic treatment or a perhaps a matching piece of carpet up to the proscenium apron/stage.


Your medium bracing remark is a little vague, but that panel material is not very rigid on it's own. Because that front panel is not likely to be very rigid as it is, it will likely behave like a diaphramatic absorber, but the range and level of absorption will be a little bit difficult without physical testing because of the additional rigidity provided by the curve will make it behave differently than a flat piece of stock of those same dimensions.


Since the front panel will be less than 1/4" material, you may have been able to turn it into a panel trap, but since it's bowed it will have additional rigidity and behave like a thicker panel. Maybe Terry, Dennis or Ethan can shed further light on what can be done.


Perhaps you could use a thinner material or create an open frame that can be wrapped in a more acoustically transparent material like GOM and then tradtional traps could be placed within the cavities to wither side of the center channel cavity.


Either way, I would definitely seperate the cavity for the size of the speaker and stuff that speaker cavity with something very absorptive, not to treat the room, but to minimize the cave like resonance of having a speaker in a cavity like that.


If you decide to skip the traps in the stage plan, the side cavities should be filled with someting inert so that tey do not add to the resonances you will be dealing with.


Many posters here prefer sand in the stage cavities. But since you mentioned moving them, perhaps stuffing the heck out them with unfaced acoustic batts would be a better choice.


Are you planning to have the speaker protruding from the face of this stage to clear the stage/apron lip?? or are you flush mounting it and making grille cloth cover to match the cloth/carpet on the face??


----------



## pajama sam

Thanks for the detailed response. I will attempt to attach a sketch of the cabinet. Since it is mostly constructed, I am reluctant to make major changes in the design. The front will be thin, but fairly rigid. I intend to paint the cabinet to integrate it with the doors and other millwork in the room. The center channel speaker has its own compartment, which is only slightly larger than the speaker itself (about 3/4" all around) and is open at the front and back, so that the grill of the speaker is visible, but flush with the cabinet front (Vienna acoustics maestro FWIW). The "hollow" 3 compartments (which I intended to stuff with insulation) are in addition to the speaker compartment. The main option still open to me is whether to seal these chambers, or provide opening ports (on the back of the cabinet), and if so, how large?


----------



## cinemascope




> Quote:
> _Originally posted by cinemascope_
> *You may still want to cover the panels, because if any portion is guilty of losing fibers, it is the rough cut ends. In place of the pricy GOM in this low visibility application, you can go econo and seek out some upholstery fabric locally that has a similar ANSI/ASTM rating for fire retardancy as the GOM.
> 
> 
> Also, the areas where you are using the panels is not entirely important from the perspective of high velocity air hitting the panels. Ductboard is made from the same material, and in a very similar manner to OC-703 panels. These materials are used to construct or line duct runs to achieve serious reductions in noise transmission through the dusctwork without causing issues from airborne fibers.
> 
> 
> Since these products have a proven track record of maintaining their integrity when faced with the high velocities inside air ducts, you can rest easy that your panels behind a false wall will not be contributing to the "itch" factor, regardless of the proximity to the HVAC vents.*



I know I am quoting my own previous post, but I just wanted to throw this on to the sticky for all eternity.


This product from Johns Manville...
http://www.jmairhandling.com/pdf/AHS-202.pdf 

...can be used to seal off the cut ends of any fiberglass sheet panels that are DIY or cut open for any reason.


The major reason is to give the panels a more sealed egde for durabilty, to prevent fraying and denting. This is especially importent for outside corners on walls, soffets, hish boxes, etc, where the edges can be dented or begin to fray with repeated contact.


A side benefit is that this is the equivelant user applied product to the solution that is factory applied to the airstream surfaces and edges of the JM duct liner material.


If ultimate peace of mind regarding shedding or fraying is an issue, you may choose to cover your panels with this product, or just choose a duct liner product to begin with.


The absorptive characteristics are different and I would count on significantly less HF absorption, but all of the specs are published so you can compare the various products and decide your plan of attack.


----------



## Ethan Winer

Scopes,


> Since the front panel will be less than 1/4" material, you may have been able to turn it into a panel trap, but since it's bowed it will have additional rigidity and behave like a thicker panel.


----------



## pajama sam

Is it essential that the "open" side be the front, I.E facing the room? The cabinet will be a few inches from the wall behind it. Would it be possible to cover the back with grill cloth instead? I was under the impression that the low frequency sound waves targeted were not very directional. Thanks!


----------



## Ethan Winer

Sam,


> Is it essential that the "open" side be the front


----------



## DennyL

I have some nasty echos in my family room which houses my home theater system. Hardwood floors, lots of glass (30%) and relatively bare walls. My wife has agreed to covering some of the bare walls with sound absorbing materials if that in turn can be covered with wallpaper. GOM or fabric may not be acceptable.


The room is 18x30 with 14ft angled ceiling. The rear of the room is open to the kitchen (18x15) and a hallway to the rest of the house.


The wallpaper is not extremely hard, but definitely stiff (but thin). I am considering covering areas with a .25" to .5" materials, some of which are recommended in this thread. My questions are as follows:


1) Will the wallpaper surface defeat the purpose here and be reflective?

2) Must I use instead a more absorbant fabric (GOM?) over the panels?

3) Is .25" or .5" enough to kill the echo and give a relatively damp room? I could do about 35% of the wall area with it if needed.

4) Should I just cover the maximum amount of wall area I can with .5", wallpaper it and hope for the best?


Thanks very much.


----------



## cinemascope




> Quote:
> _Originally posted by DennyL_
> 
> I have some nasty echos in my family room which houses my home theater system. Hardwood floors, lots of glass (30%) and relatively bare walls. My wife has agreed to covering some of the bare walls with sound absorbing materials if that in turn can be covered with wallpaper. GOM or fabric may not be acceptable.
> 
> 
> The room is 18x30 with 14ft angled ceiling. The rear of the room is open to the kitchen (18x15) and a hallway to the rest of the house.
> 
> 
> The wallpaper is not extremely hard, but definitely stiff (but thin). I am considering covering areas with a .25" to .5" materials, some of which are recommended in this thread. My questions are as follows:
> 
> 
> 1) Will the wallpaper surface defeat the purpose here and be reflective?
> 
> 2) Must I use instead a more absorbant fabric (GOM?) over the panels?



The paper isn't the issue as much as the adhesive that soaks into it and dries stiff which makes that paper so crispy. If you havce ever removed old paper without a steamer or the release agent, you understand the term.


I have seen some wonderful papers based on softer materials that look tremendous. It's just that they get stiff as a board when the adhesive soaks into the back layer of paper.


Some of the finest homes I have ever been in had expensive fine fabric with a wallpaper style pattern strecthed over the walls and suspended just off the wall surface. I don't know what this method is called, but then again I don't subscribe to Architectural Digest...

There was a little bit of deflection to another wall substrate if you pressed your finger against it. Something like this would allow you to use a thin duct liner of fiber panel material in the trouble spots determined by the mirror method or a ray trace.


This may be a better solution if you can give up a little more space and fit it into your budget.



> Quote:
> 3) Is .25" or .5" enough to kill the echo and give a relatively damp room? I could do about 35% of the wall area with it if needed.
> 
> 4) Should I just cover the maximum amount of wall area I can with .5", wallpaper it and hope for the best?
> 
> 
> Thanks very much. [/b]



.5" is better than .25", and .25" is better than nothing...

I am still not sure that fiber panels are the best solution for your application.

Even if the stiff paper didn't reflect, I doubt it would bond well to fiber panels.


If you research the stretched fabric method and it is not your wife's cup of tea, or it is a budget breaker, another option to look into is a skimcoat of acoustical plastering.


Nearly any plaster contractor in the phone book has availiability to acoustical plaster and understands it's application.


The absorption characteristics, and therefore the results, are based on variables like how thicky it is applied, etc. and an acoustician would generally specify these variables for it's use.


To read more for yourself, go here:
http://www.usg.com/navigate.do?resou...ter_Finish.htm 


Another choice is a new system from Switzerland called BASWAphon that RPG offers in the US.


Famous acoustical guru John Storyk used this system on a This Old House project, and you can read about that here.
http://www.thisoldhouse.com/toh/know...216779,00.html 


Read the section of the article called "Mid- to High-Frequency Reflection Control" where he descibes a new product he used in that room.


As I said, RPG distributes this material, and you can read more info here:
http://www.rpginc.com/products/baswaphon/ 


I am not positive if you can paper over this.

I'm thinking you cannot, because you actually don't even paint it.


You tint the plaster material before it is troweled and skimmed.


I would send out a letter to RPG to confirm.


Either this new material, or the skimcoat method with traditional acoustical plaster to a lesser extent, can help make a room less "live" yet still retain the traditional aesthetic apperance.


Either method should allow your wife to paper the space, but as I said, double check with the manufacturer of the panels before you order them.


If you want the best results (and some quality entertainment) call in a acoustician and an interior designer and let them battle it out.

Right now you and your wife are having that debate on a smaller scale, when it's two pros that are each dead set against each other's plans and both very good at what they do, it's not pretty...


----------



## rabident

Any words of wisdom for non-standard rooms?


All the advice in this thread seems to assume a basic rectangle / shoebox / golden ratio room. What about sloping ceilings/walls on both sides? Basically a barn like room that many people get when they finish off attic space. Also, how about half walls that form ear level and below U shaped squares in the back of the room. Or hallways / stairwells leading into the room?


----------



## Terry Montlick




> Quote:
> Originally Posted by *rabident* /forum/post/0
> 
> 
> Any words of wisdom for non-standard rooms?
> 
> 
> All the advice in this thread seems to assume a basic rectangle / shoebox / golden ratio room. What about sloping ceilings/walls on both sides? Basically a barn like room that many people get when they finish off attic space. Also, how about half walls that form ear level and below U shaped squares in the back of the room. Or hallways / stairwells leading into the room?



Such rooms can make excellent theaters. Acoustical modeling and prediction isn't straightforward, however. Ray-tracing will model a room well at most frequencies. But it doesn't perform well at the lowest frequencies, so it won't tell you much about room modes. The Finite Element Method (FEM) is the technique of choice for analyzing modes in odd-shaped rooms. We do pre-construction HT analysis at reasonable prices, and have capabilities to do both professional ray-tracing and FEM. If interested, PM me.


Regards,

Terry


----------



## bpape

Every room is different. We'd need more information and specifics like sizes, seating locations, speaker locations, how many people, usage, etc. before being able to give even a basic recommendation.


That said, the basics are pretty much the same. Kill the front wall, kill the reflection points, address the reverb time in the room appropriately throughout the spectrum, etc. How much, what kind, and where will depend on the answers to the specifics.


----------



## Westshorestudios

I want to treat my dedicated theater for absorbtion at first reflection points. My first question is: (1) What are the pros / cons of attaching OC 703 / 705 / or equivalent (covered in acoustically transparent fabric) directly to the drywall rather than in wood framed panels? If attached directly to the drywall, am I really helping any or just spending money?


My second question pertains to sound insulation (i.e., keeping outside of the theater sounds out, and inside the theater sounds in). My construction is double 2x4 walls with a 1/4 inch air gap between the 2 walls. The outer wall will be filled with 3 1/2 inches of expanding polyicynene foam (the spray in stuff that expands 120x). The inner wall I intend to fill with fiberglass batts.


(2) For the fiberglass batts, does it matter if they are faced or unfaced, and if faced, whether the face "faces" in or out? And does the foam or fiberglass in the wall provide any acoustic benefit?


Thanks


----------



## bpape

First for the isolation... IMO the expanding foam does little or nothing to assist in isolation as I believe most of them are closed cell foams. You'd be better off with standard fiberglass and a barrier on the outside of the outer wall.


For the absorbtion inside the room... You can certainly be effective mounting 703 directly on the wall - provided it is thick enough to do what you need done. 2" of 703 framed 2" out from the wall will reach deeper than 2" directly on the wall but not as deep or as tight as 4" directly on the wall. Also, the 4" and the 2" spaced off the wall will do no more from say 1kHz up than the 2" mounted to the wall. What changes is how far down they're effective and at what level of effectiveness.


As for facing, again it depends on what you need. Usually one uses unfaced. However, if you only want bass/low mids absorbtion, you can certainly use FRK with the facing out into the room.


The insulation inside the wall keeps it from ringing and assists the drywall over stud construction to act like a broadband resonant panel trap that is pretty effective from say 100Hz through around 250Hz+.


----------



## Westshorestudios

Bpape - Thanks for the info.


Next: Is there a material that can be used in place of gypsum drywall (i.e., paintable, firm, etc.) but has the characteristics of rigid fiberglass with respect to absorbtion? If so, wouldn't that be a good solution for walls and ceiling? That way, all surfaces are built in bass traps, then, to prevent room from being too dead, reflectors / diffusors could be added as needed. Benefit would be that a diffuser / reflector doesn't need to be inches deep.


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## BasementBob

Most expanding foam insulation in the wall is worse than having nothing in the wall. It's rigid and closed cell and conducts sound. It's a good thermal insulator, but worse than useless for acoustics and sound proofing.

'Expanding polyicynene' you mention may be Icynene, which is an open cell foam with absorbtion , in which case it's fine. Less absorbtion than some other products, but probably better air tight seal. Search for Icynene at AVS and you'll find someone who's had it installed.


If you can avoid faced fiberglass, it's probably better. But if you must use faced, I believe the recommendation is to put the facing against the drywall rather than into the gap, both because that has acoustic benefits, as well as it's the way it's designed to be installed. There may be vapor barior issues. Lightly filling the entire cavity (no airgap) with insulation may have firestopping benefits.


Attaching the absorber directly to the wall is fine. Impailing clips may be what you want to attach it with. Spacing it out from the wall gives you more absorbtion at lower frequencies for free, which may be a good or bad thing depending on what other absorbtion you have in your room (e.g. 20 leather seats).


The job of gypsum/drywall is to be cheap and reflective and firesafe, i.e to use it's mass and reflectivity to keep the sound energy in the room, rather than letting it out of the room. Similarly to keep the sound energy outside of the room out, to lower the noise floor and thus increase the dynamic range of the HT. If you're into soundproofing, don't think of it as an absorber, and don't try to make it into an absorber.


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## Westshorestudios

Thanks. It is icynene foam. I'll do the search for icynene & see what the avs experience / expertise is.


Greg


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## cinemascope

There are two types of polyicynene spray in foams, high density and low density.


The high density variety is the closed cell product that the fellows are warning you to avoid. It makes a very rigid wall system that will transfer noise through with little loss.


This type of foam is generally used below grade where moisture is a concern.

Remodelers love to use it against stacked stone and block foundations because it expands into every crack and crevice and has enough structural holding power to bond the wall together and help keep the foundation from future disentegration.

In addition, it is an absolute moisture barrier for these notoriously leaky foundations.


Low density, or open cell polyicynene foam insulation is a great product to use in your application, but in the outer most portion of the double wall. It has similar vapor barrier characteristics of the closed cell products, but it will not trap moisture. (no mold)

It is generally specified for use above grade.
http://www.icynene.com is the major player in open cell.


Faces in or out on batts has to do with vapor barrier, and this varies by your location.

Gulf coast areas need the barrier out, or more likely they will use an external barrier and unfaced batts. The rest of the country requires it to be on the inner most section of the cavity.


If none of these walls is an exterior wall, use unfaced batts. If one or more walls are exterior, use the open cell spray, or consult the insulation contractor or building inspector to make sure your walls will meet any code requirements.


Nothing will slow down a project faster than having to re-do an expensive part of the project that you have done incorrectly. It's worth getting right the first time, air quality concerns are high on everyone's list when selling/buying a home, and mold remediation is EXPENSIVE.


In the wall closest to the room, I would recommend acoustic fiberglass batts. I like the Johns Manville batts because they perform well and are also formaldehyde-free.


It sounds like you have a nice project going, you should create a thread and post photos and updates as to the progress.


Best of luck.

--Rick


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## Westshorestudios

Rick - thanks for the help. I agree that getting it right the first time costs a lot less than changes later. I'm trying to do everything possible to get it right! In fact, I made the a/c people come out today and replace the existing "boots" on the end of the ducts with oversized boots, so that the conditioned air as it enters the room will be slowed down somewhat.


Is creating a thread for one's own room pictures ok? Not sure of the protocal and whether that is something ya'll do and is in good "form" or whether that is "bad form," etc. If it's "proper", I'd be pleased to share my labor of love (or maybe lust is a better word when talking about a home theater!) with all of you!



Greg


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## kromkamp

I personally did use closed-cell foam in my basement HT, and I'll tell you why.


I'm firmly convinced that the BSC method of insulating basement walls is the correct way to go. This method employs no vapor barrier but instead a vapor retarder, to allow moisture to dry to the interior at a slow, controlled rate (since it cannot dry to the exterior below-grade).


Closed cell foam of approx. 1" is a vapor retarder (perm ~1.4). Open cell foam is not (perm ~15). I've also heard a lot of bad things about open cell foam - the expansion rate is so great that there are often huge (ie. inches wide) air bubbles in the foam that severely compromise the R-rating.


Yes, this may mean I have compromised sound attenuation. IMO the fact that they are foundation walls (ie. only consideration is flanking noise) and the fact that double-drywall w/ damping is going to do 100X more than 3.5" of fiberglass ever would just isnt worth the tradeoff of possible mold issues. Yes lots of homes dont face mold but lots do. If you consider all those older homes that have a 'musty basement', thats a mold issue.


Just my 2 cents.


Andy K.


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## suffolk112000

I have a friend with a set-up that is on the bright side. (Klipsch 7.1 with a Yamaha 2500 receiver)

Originally, his room was horrible. His system was in an 18X23 drywalled room with 9 foot ceilings and a ceramic tiled floor.







It was an echo chamber.

He has since put in two large, thick rugs and hung some dense curtains all the way across the front of the room. (Helped a ton) Now that he has seen these improvements, he wants more.

He now wants to tone down the brightness of his set-up.

He really does not want to put up GOM if he does not have to, but would if there are no alternatives.

I told him he should treat the room (Knauf/batting/GOM) and be done with it.

It is probably what he will end up doing anyways.

Is there a way to reduce brightness in a room with out going all out with treatments.

And, if he does treat the room, will his speakers not sound as bright?


Craig


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## bpape

Treating the room will not change the frequency response that the speakers yield. What it can do is to tame the reflections and bring the reverb time more under control.


However, treating only the mid/top of the spectrum is not a good idea. The whole spectrum should be addressed.


As for covering, you can use Muslin dyed to the color of his choice - for treatments this will work just fine. You can get lightweight muslin at JoAnn Fabrics for


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## suffolk112000




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Treating the room will not change the frequency response that the speakers yield. What it can do is to tame the reflections and bring the reverb time more under control.
> 
> 
> However, treating only the mid/top of the spectrum is not a good idea. The whole spectrum should be addressed.
> 
> 
> As for covering, you can use Muslin dyed to the color of his choice - for treatments this will work just fine. You can get lightweight muslin at JoAnn Fabrics for
> 
> 
> Thanks bpape,
> 
> 
> I will show him this post... except the part I called his room an echo chamber.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I think he is seriously considering using wall treatments.
> 
> He is not a real audiophile and at least for now I think he is going to live with what he has.
> 
> He wants to see what my theater sounds like when I am finished with mine before he undertakes it though.
> 
> Next, I have to get him to paint his white walls and ceiling a dark color.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If anyone has more to add on this please feel free to chime in.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Craig


----------



## Equusz

Hi all, great thread - I finally made it through! I'd like to post some questions and get expert feedback.


Building a dedicated theater room in the basement of my new home. The room will be 16' x 24' with two levels of riser. Top level will have concession stand, equipment rack, maybe a popcorn machine, etc. 2 theater seats centered on it, room permitting. Next level, row of 4 reclining theater seats. Floor level, another row of 4 theater seats. When they frame it I'm going to just have them mud, tape and prime the front wall but not texture it, and that will be my screen, after I've Goo'd it and trimmed it. 7 speakers in the ceiling (I was thinking of the Russound series of ceiling speakers that you can aim so the sound goes in the right direction instead of straight down).


So, for acoustic treatments, I was reading from this article which maintains it's acceptable to keep some of your painted drywall as reflective surface and put up panels in the hot spots. I was thinking of building shaped panels like in their models and putting them in the primary reflective areas as discovered using the mirror test. I would also put bass traps in each corner like the ones described here . There will be thick carpet and I'll also put panels on either side of the screen, and perhaps a bookshelf along the back wall to diffuse some of the sound without deadening.


Do you think this would work well? The room doesn't have to be perfectly tuned but I'd like it to be nicely acoustic with not too much echo.


Also, does the subwoofer have to be in the front? I was going to put it next to my equipment rack in the back.


And how thick do those panels have to be? I think anything more than 4" would stick out like a sore thumb.


Thanks for your advice!


Equus


----------



## bpape

Yes. That plan will work fine. The trick is getting not only panels in the right places, but getting the right balance of materials so you're dealing with the enitre spectrum equally from a decay time standpoint.


The thickness of the panels will be determined by what the room needs and what the specific application of each panel is.


As for speakers, at a minimum, get speakers that fire toward the audience for the front 3. If you must do in-ceilings for the rest, at least that's not as bad. If you put in-ceilings in the front, you'll have absolutely no shot at locking the sound to the image and you won't get anything in the way of an aural image. Check out some other companies. If you're budget challenged, there are still other companies that make reasonably priced ceiling and/or in-wall speakers that will do a lot better than the Russounds.


Good luck.


----------



## Equusz

Hi bpape:


Thanks for your response. I know in-ceilings are generally not good for imaging, but I was "told" these Russound speakers with their aimability would work well. Do you think that's not the case? If so, do you then have better suggestion in the same price range? I don't think I'm going to have much room over the top of the screen for the center-channel speaker, as I'm going to try to make the screen height almost the entire 10' floor-to-ceiling distance. That's what got me looking at in-ceilings in the first place.


And do you think it's OK to put the subwoofer in the back? Or is that a bad idea? I forgot to mention that each of the seats also has a "buttshaker" sub in them as well.


Equus


----------



## bpape

First, you need to see what your room, your seating distances, and your PJ will support in terms of picture size. Bigger is not always better. On top of that, if your screen is almost to the ceiling, you're probably going to be pretty uncomfortable watching movies with it up that high. Usually, you want your eye level about 1/3 up on the screen.


If you can't put the center above, then do it below. No. I don't think ANY in ceiling speaker is going to do a good job across the front. You really need to lock the sound to the image. The movable tweeters are OK but the rest is still firing straight down and that extreme off axis response is not going to be even close to flat across multiple seating positions.


You might want to put this in the normal area of home theater construction. It really doesn't belong in the acoustics thread.


----------



## Equusz

Well bpape my main questions were of acoustic panels and bass traps, so I though appropriate to this forum. I'll look into what you said about ceiling speakers and screen size. Thanks for the advice.


Equusz


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## usualsuspects

My room is 22x14x8. I am looking at bass trapping and first reflection sidewall treatments as a staring point. My thought on corner bass traps: floor to ceiling OC 705 two foot hypotenuse with no airspace behind - basically fill the entire corner out to two feet. My grade school math is a little rusty but my calcs make it: 2' hypotenuse = 1.4142 feet out on each side wall = 1 square foot = 1 cubic foot per vertical foot x 8' = 8 cubic feet per corner. I can only do 3 corners because a door is in one corner - I could put 1 cubic foot above the door. That's 25 cubic feet and that's before any first reflection point treatment. My questions: is 25 cubic feet of 705 as a starting point too much? I know that different frequencies are absorbed at different rates, but I have no idea what this will do to the sound of a room that size - any opinions? Also: to FRK or not FRK? My plan was to cut triangles of 705 and stack them - that puts the FRK (if any) as a horizontal sandwich.


----------



## BasementBob

usualsuspects :

Studiotips Super Chunk including 24" and 34" cut pattern 
Harder's super chunk 
48" cut pattern 

Studiotips Corner Absorber 



> Quote:
> I can only do 3 corners because a door is in one corner



Left/Right symmitry is a good thing. Consider 2 corners.


Just say no to FRK.



> Quote:
> That's 25 cubic feet and that's before any first reflection point treatment.



Yes, but two corner chunks, even floor to ceiling, are not very much surface area. As you'll likely have modes down to 25hz or so, broadband traps effective down to bass are a good thing -- big traps are probably fine. Consider wall/ceiling corners (overhead like soffits).


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## Westshorestudios

Hi - If I want to do some sound deadening between rooms (not theater, just other rooms like bedrooms and bathrooms) and plan to use fiberglass battes between the 2x4 wood studs, am I better off with 3 1/2" batts (those that are designed for thermal insulation between 2x4 studs), OR going with a 5 1/2" thick thermal batte, and "squishing it in" between the sheet rock (probably not good for thermal insulation, but possibly better for killing sound transmission)?


I'm not interested in double sheet rock, green glue, quiet rock, RC, staggered stud, etc., etc., etc. Just what is the best thickness of fiberglass batte to use in a 2x4 interior stud cavity for reducing sound transmission.


Any ideas?


Thanks.


Greg


----------



## PAP

For that application, the more the better.


----------



## Todd_zilla

Westshores,


You may want to check with your friendly HVAC guy before throwing that kind of insulation between interior walls. Unless you have air returns in each room, you may be causing some issues with your air flow and temperature regulation... just a thought.


----------



## Todd_zilla

Hi Guys,


I'm toying around with the idea of using acoustical ceiling tile to cover the walls of my theater (velcroed onto the walls - floor to ceiling - either wrapped in fabric or painted). These acoustic panels have a Noise Reduction Coefficient (NRC) of .55 up to .90. Can some of you sound experts help explain what this would do to the acoustics in the room? Also, are the acoustical properties of these panels affected if you paint them? The panels are 5/8 of an inch wide... which is good, because I don't have any inches to spare in the width of the room. Please help...


----------



## Carlton Bale




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/0
> 
> 
> Hi Guys,
> 
> 
> I'm toying around with the idea of using acoustical ceiling tile to cover the walls of my theater (velcroed onto the walls - floor to ceiling - either wrapped in fabric or painted). These acoustic panels have a Noise Reduction Coefficient (NRC) of .55 up to .90. Can some of you sound experts help explain what this would do to the acoustics in the room? Also, are the acoustical properties of these panels affected if you paint them? The panels are 5/8 of an inch wide... which is good, because I don't have any inches to spare in the width of the room. Please help...



I think it was mentioned earlier in this thread that ceiling tiles are too rigid and not as effective at the necessary frequency ranges. The fiberglass materials mentioned in this thread are a better option.


----------



## Todd_zilla

Do you know of any fiberglass panels that are approximately 1/2 inch wide that would help?


Also, I'm not sure I understand what rigidity would have to do with sound absorption...


----------



## Terry Montlick




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/0
> 
> 
> Do you know of any fiberglass panels that are approximately 1/2 inch wide that would help?
> 
> 
> Also, I'm not sure I understand what rigidity would have to do with sound absorption...



Hi Todd,


1/2" thickness is usually too thin to extend down enough into the bass frequencies. There is actually an acoustical tile which works very well. This is Armstrong OPTIMA Open Plan, but it is 1" thick and fiberglass.










Rigidity doesn't effect sound absorption, but fiberglass density does. The best fiberglass for HT sound absorption ranges from around 2.5 pcf to 6 pcf.


Regards,

Terry


----------



## Todd_zilla

Hi Terry and thanks for the info...


Would an acoustic tile treatment on the walls and ceiling using a 1/2 inch acoustic tile (like the Armstrong Pebble - .70 NRC) combined with bass traps in the front corners of the room work OK? Would putting the Optima Open Plan everywhere be OK, or would it be over kill?


Also, does it affect the acoustic performance of these tiles if they are painted?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/0
> 
> 
> Hi Terry and thanks for the info...
> 
> 
> Would an acoustic tile treatment on the walls and ceiling using a 1/2 inch acoustic tile (like the Armstrong Pebble - .70 NRC) combined with bass traps in the front corners of the room work OK?



I think you may be likely to end up with a reverberant "hump" in the middle frequencies, where neither the tiles nor the bass traps give sufficient coverage. And the NRC of 0.70 for Armstrong Pebble is for E-400 mounting, which has a 400 mm air space in back of the tiles. Your mid to low frequency absorption will be nowhere near the E-400 mounting specs when the tiles are mounted right against a wall (A mounting).



> Quote:
> Would putting the Optima Open Plan everywhere be OK, or would it be over kill?



Everywhere may overkill, depending upon your room. But if you use these tiles, you could also just go with 1" fiberglass. The only advantage to the tiles is that they have a finished surface, which doesn't need fabric covering.



> Quote:
> Also, does it affect the acoustic performance of these tiles if they are painted?



Yes. Don't even think about painting them.










Regards,

Terry


----------



## Todd_zilla

hmmm... bummer. I thought I would save the expense of the fabric if I could simply paint the tiles. Plus, I'll have to paint the ceiling tiles black for the starfield... or I guess I could just cover those in fabric too. I just need to put a "loose" fabric that permits the sound to travel through to the tiles or fiberglass, right?


----------



## Todd_zilla

Anyone ever hear of "AudiMute Pro Acoustical Covering (NRC=.70)"? It basically looks like a quilted blanket that is supposed to be used for acoustics. Curious to see if anyone knows anything about it...


----------



## bpape

If it looks like a blanket, unfortunately, it will also likely perform like one. Good absorbtion in the highs and down into the mids and nothing on the bottom.


----------



## Todd_zilla

Lab report for this product can be found here:

http://www.audimute.com/AMP.pdf 


Maybe you guys could help with interpreting the numbers or if this sounds legit. Would this product combined with some bass traps perhaps do the job???


----------



## HTNewbie1974

Hi guys,


I decided to bring my HT questions to this thread since this is the one about acoustic treatment, so here goes>


See attached pictures to get the idea of what I'm talking about in the questions


1.- For high freq abs. I'll build 4 panels, put 2 in the right wall and 2 in the left wall, but I'll make an array. The 2 panel arrays I'm thinking would be composed of 2 2 X 4 panels and 2 2 X 2 paintings, all combined to form a big square, that absorbs the high f. and also decorates a little.


2.- What are the consecuences of hanging a large Horse painting in the back wall? Could I put something behind the painting to improve absorption?


3.- With all the information about bass traps I am really confused. Should I just buy a tube and fill it with dirt or sand? or should I build a couple of tick panels and put them on 2 corners? up front?


4.- I will put a rug on the floor, so should I also consider something for the ceiling?


5.- What sould I do about the front wall? another 2 2X4 panels on both sides of the TV?


6.- Is the back wall in need of diffusors?, maybe 1 difusor on each side of the Horse painting?


----------



## HuskerHarley




> Quote:
> Originally Posted by *HTNewbie1974* /forum/post/0
> 
> 
> 
> 2.- What are the consecuences of hanging a large Horse painting in the back wall? Could I put something behind the painting to improve absorption?



Straw/Hay










HH


----------



## Terry Montlick




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/0
> 
> 
> Lab report for this product can be found here:
> 
> http://www.audimute.com/AMP.pdf
> 
> 
> Maybe you guys could help with interpreting the numbers or if this sounds legit. Would this product combined with some bass traps perhaps do the job???



Hi Todd,


This spec sheet gives numbers for G75 mounting. That means hung as a drapery, 75mm from the wall. This is such a rare spec that it's nearly impossible to compare it to any other material! It is only valid if you hang this product 75mm (3 inches) from a wall, which gives it a big bass absorption boost.


Regards,

Terry


----------



## Todd_zilla

Thanks Terry... I thought it was fishy, but I didn't know what the "catch" was...


I guess I'm back to 1 or 1.5 inch rigid fiberglass insulation and wrapping it in fabric. What do I need to look for and how much should I expect to spend? I guess I can compare that price to the price of the Armstrong Optima Open Plan tiles and go from there. I'll have to wrap either one in fabric.


I'm guessing that I'll also need bass traps to go along with the wall treatments...


----------



## bgarner

I figured I would post my question in this thread rather than starting a new thread.


I have read thru the entire thread as well as read lots of recommended sites and I was able to get rid of about 80% of the echo problems I was having. First I insulated the right wall where the furnance room is which helped quite a lot, then I puchased some Roxul Safe N'Sound 3" insulation and placed it around the speakers and front wall to see if I could elimanate this wierd echo I was getting.


Well after watching some movies, I did notice that it was still there, althought not as bad as before and only during silent parts where the person is talking. This echo problem seems to happen only when something is coming out of the center channel. The problem doesn't seem to appear when I put the receiver in stereo mode. Also, I have the fronts and center bi-amped to an external amp, which is when I started noticing the problem.


Anyways, the echo it seems is coming from my Da-lite 16x9 screen. If you go under it and talk, you get an echo and you can tell it clearly comes from the metal around the screen. I have attached a picture and as you can see, my center channel is below the screen in the cabinet about 1/2 foot behind the screen, although the screen isn't covering it as the screen only drops to the top of the cabinet covering the television.



My question is, What can I do to get rid of the echo coming from the metal around the actual screen.


I will be shopping around for material to use to cover the insulation and I will do the mirror trick as well. I figure to use 8 of these between the front and side by the speakers. The room is 30' x 11' and has an opening to a hall between the first and 2nd row of seating.


Any suggestions on my next steps?


Thanks,


----------



## BasementBob

bgarner:

What happens if you hang a duvet/comforter down the back of your screen?


----------



## bgarner

Haven't tried that but will get right on it to see what happens.


----------



## bpape

My suggestion would be to get that center channel out from under that shelf by moving it forward at least past the front of the cabinet. That, in itself, will cause some issues regardless of the screen.


----------



## bgarner

Unfortunately, the Center Channel is bigger than the actual cabinet, so I don't have too many options. If I put it on top of the cabinet, then it will be louder when the screen is not down, if I set it up with the screen down and vice versa if I set it up with the screen not down.


----------



## Todd_zilla

Can anyone give me a ballpark price on what 1 and/or 2 inch rigid fiberglass should cost? Thanks in advance...


----------



## Todd_zilla

Also, can anyone tell me if a "basketball shorts" mesh fabric is OK to use... very porous, so I'm thinking it will be OK. Please advise...


----------



## Ethan Winer

Todd,


> ballpark price on what 1 and/or 2 inch rigid fiberglass should cost?


----------



## bpape

From my supplier, the FRK facing products are over a 50% premium AT MY COST over unfaced. I've started the process of just getting the FRK scrim to sell so people can make their own - even then it will add about $2 to a 2x4 panel.


----------



## bgarner

When building the panels, is it necessary to cover the back with fabric, or do you cover only the front with fabric? I will be using 3" Roxul insulation.


Any help is appreciated.


Brian


----------



## BasementBob

bgarner:

Acoustically, assuming that you can breath through the fabric, it makes no difference at all.


The purpose of the fabric is to keep the insulation in place, to keep the fibers in place, to protect the trap from people touching or brushing against it, and for asthetics (i.e. it looks better).


If none of those are a concern with the back (such as a frame is against the wall), then you don't need covering on the back.


----------



## bgarner

Thanks for the informaton. Off to get some materials and start building.


----------



## HTNewbie1974

What's better? a cilinder bass trap or an absorption panel cut like a triangle and installed on a 2 wall/celining corner?


I was thinking of adding 2 triangles to the corners, using unicel panels covered with fiber glass and fabric, what do you guys think?


By the way, anyone knows if unicel is a good sound absorver?


Regards!


----------



## bpape

Why the limitation? Obviously, the cylinder has a LOT more surface area and will provide more absorbtion. However, if you're willing to give up the floorspace the cylinder takes up, why not consider using flat panels straddling the corner at 45 degrees for the top 4' or maybe even floor to ceiling?


----------



## GetGray




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Why the limitation? Obviously, the cylinder has a LOT more surface area and will provide more absorbtion. However, if you're willing to give up the floorspace the cylinder takes up, why not consider using flat panels straddling the corner at 45 degrees for the top 4' or maybe even floor to ceiling?



In this config, what do you recommend to "cap" the end of the partial corner covering? Or leave it open?


----------



## Ethan Winer

Gray,


> do you recommend to "cap" the end of the partial corner covering?


----------



## GetGray




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Gray,
> 
> 
> > do you recommend to "cap" the end of the partial corner covering?


----------



## bpape

No need to do anything to it unless you want to for looks purposes and/or to have something to staple the fabric to on the bottom.


----------



## Ethan Winer

Gray,


> for a corner with a 2x4 panel stood in the corner, from ceiling down the wall 4', capping it (in other words, adding a base to it) it will have no significant effect?


----------



## GetGray




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Gray,
> 
> 
> > for a corner with a 2x4 panel stood in the corner, from ceiling down the wall 4', capping it (in other words, adding a base to it) it will have no significant effect?


----------



## bpape

You'll be fine if you put a bottom on it. As I said, you need something to staple to anyway unless you're doing a free hanging frame. If you want the best of both worlds, cut a triangle for the bottom and then cut a hole in it to leave say 1-1/2 inch all around for attachment.


----------



## GetGray




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> You'll be fine if you put a bottom on it. As I said, you need something to staple to anyway unless you're doing a free hanging frame. If you want the best of both worlds, cut a triangle for the bottom and then cut a hole in it to leave say 1-1/2 inch all around for attachment.



Understood, sounds like a plan. Thanks.


----------



## HTNewbie1974

Good question about the 3 scenarios


I was thinking of doing a triangle to cover the corner, but would it be better just to build a 2X4 panel and hang it on the corner, touching the ceiling? As in case 2?


I like the triangle idea because of the looks


Now, I know this has been explained a million times, but, if I do a panel as a bass trap, the paper side of the fiber glass would face the room and the pink stuff would face the corner right?, oposed to a high freq. panel where you place the pink stuff facing the room. Am I correct?


----------



## Ethan Winer

Gray,


> This "floor" caps the bottom of the trap


----------



## Ethan Winer

Newbie,


> the paper side of the fiber glass would face the room


----------



## bpape

Ethan,


His point was that if you run an absorber floor to ceiling straddling the corner, you'll not get anything in behind it either. Very true.


----------



## Ethan Winer

Bryan,


> His point was that if you run an absorber floor to ceiling straddling the corner, you'll not get anything in behind it either.


----------



## bpape

No. You'd just have 2 smaller cavities for it to get into. The whole idea was that you were saying that putting a bottom on it lost the ability for sound to get in via the bottom where it was open. In a floor to ceiling, it's the same thing. Anything that gets in has to come through the panel.



Sure, if you leave the bottom of a half corner trap open, there is more opportunity for sound to get in from the bottom. However, that does not make what is dealt with via that which comes in from the panel any less effective. You just don't get the 'bonus'.


----------



## HTNewbie1974

Hi guys!


I finished my 2 triangles for bass traps


The are aprox 2 feet on each side


Now the problem is, how on earth do you hang those on the top corner? I have concrete walls and would probably have to drill.


Anybody has any idea on how to do it?


----------



## bpape

So these are equilateral triangles that just sit in the tri-corner? If so, and there's a wood frame around it, heavy duty velcro might do the trick - otherwise, a SMALL dab of construction adhesive would likely work - you'd just have to hold them in place somehow till it dries.


These assume you made the sides of the frame at the appropriate compound angle so each edge will sit flush with the wall/ceiling.


----------



## DMF

Can you hang them from the ceiling?


----------



## RJP3

(MISTAKENLY POSTED IN MAIN FORUM, WHEN I MEANT TO PUT IN THIS THREAD.)


Looking for appropriate combination and placement of acoustical wall panels for sound absorption and diffusion.


Room specs are as follows:


- basement location

- 18w x 16d x 7.75h

- 2x4 stud walls with 5/8" sheetrock, painted

- drop ceiling with pretty good "acoustic tile"











HT system specs:


- 50" Plasma, wall mounted (PIO 5050HD)

- 7.1 surround

- DefTech speakers, as indicated on diagram

- speakers wall mounted

- surround back speakers are bipolar


Aside from all the usual concerns, I'm particularly worried about:


- the angled corners on the back wall

- not "killing" the effect of the bi-polar speakers on the rear surrounds


Would love for any of the cogniscenti to provide a "stepped" recommendation? ("First you MUST do this, then you SHOULD do this, and then you COULD do this...etc")


While I'm pretty handy from a DIY standpoint, I'm really hoping to go with "ready to wear" fabric wrapped panels and the like.


Thanks in advance for your time and consideration!


----------



## bpape

This should probably be in the main forum or in the audio theory area.


----------



## HTNewbie1974

Hi guys!


Yesterday I had a hard time hanging my triangle bass traps, I decided to use fishing line to hang them to the corners, but it was fisically imposible to put the triangles all the way up, so I left some space between the triangle and the ceiling.


Ethan once mentioned that if air can enter this type of bass trap, it would be a good thing, so in my case, I'm in the good zone right?


Check out the diagram...



2 more weeks to get my Samsung 60"!!!


... almost there... stay on target....they came .. from... behind!!!


----------



## Ethan Winer

Newbs,


> Check out the diagram...


----------



## kromkamp




> Quote:
> Originally Posted by *HTNewbie1974* /forum/post/0
> 
> 
> fisically



Hmm.... (sorry, not usually a spelling nazi but.... )


----------



## HTNewbie1974

Sorry about the word I invented!, feel free to correct me if I write something crazy like "fisically"


In other news , yesterday I finished hanging the treatment panels on the walls, and I figured a way to put the triangles exactly in the corners, using the same fishing line.


Attached are a couple of pictures of the left and right walls , as well as the treated corners.


The rooms looks small, but I think it's fine.


Feel free to comment on my panels, I haven't tested that configuration since I still don't get the equipment. You guys think it'll work?


Panels are 2X4, 2" deep

Triangles are 2X2X2, 2" deep


----------



## bpape

It should help some. It would be more effective if they were 4" thick and maybe had a little more surface area - but they look very nice - good job.


----------



## HTNewbie1974

Thanks!


I will also add a nice rug that covers some area of the floor, but for the ceiling, back and front walls I'll do nothing


So, would you guys say, "ok, you're good to go" or more like "dude, you just covered the tip of the iceberg and you need to add more!!!!"


The wife acceptance factor is limiting the amount of panels, I was lucky to be allowed to have 4 and 2 triangles










Regards,


----------



## bpape

Try it and see. IMO, you're likely to need more bass absorbtion but what you have is better than nothing. At least with the panels you have, if placed correctly, you'll be way ahead of the game over most people in terms of controlling decay times, taming early reflections, and at least minimal broadband bass absorbtion.


----------



## HTNewbie1974

How dangerous is it to place a spot light near a fiberglass panel? you guys know of any case of a panel bursting into flames because of overheating from direct light from a spot light?


----------



## DMF

I didn't know fiberglass was flammable ??


Is it straight fiberglass, cloth-covered, resin-impregnated? What kind of light? How far away?


----------



## HTNewbie1974

it's covered in fabric and poly batting, with a wood frame


----------



## HTNewbie1974

here's a picture


notice the spot light just ahead of the tiangle panel, that's the one that has me worried


----------



## bpape

If the cloth is fire rated, there should be NO concern. Even if so, you're far enough away from it that it shouldn't cause a problem IMO. Direct contact is another issue but you're inches away.


----------



## BasementBob

HTNewbie1974:


> Quote:
> How dangerous is it to place a spot light near a fiberglass panel?



How about "if you can keep your hand between the heat source and what you're worried about for ten minutes, then it probably won't ignite or prematurely discolour. If you can't keep your hand there, then move it away or put drywall between them."


BTW, first glance at your left wall.JPG , I thought the text on the wall was "Parking Area". (After resizing the image, it turns out to be "Painting Area".)


----------



## usualsuspects

I am about 1/3 of the way done reading - Master Handbook of Acoustics - 4th edition - Everest. I wish I would have bought this book long ago. It is the best $40 I have ever spent on my theater. If you are in any way interested in theater / music acoustics - get this book!


----------



## piercedb

Yet another question about panel construction...


Has anyone tried to make a panel wider than 2'? I could spare a wider than 2' panel in the corners of my room, but don't want to make a tube trap as the fibreglass tubes are far more expensive ($24 per lineal foot, 20" dia, 2" th, ouch!). I could make them 2.5' or 3' wide, but am unsure if just gluing them together would work. I have only been able to find 2" 705 and 3" 703 locally. Not sure if this will solve the issue completely so want to overdo it the first time. I included a drawing of the room in case it helps.


Another question, which is more theoretical. If the FRK (faced) panels also work, then is the fibreglass actually slowing the air velocity or is the panel simply flexing? If I really care more about bass absorption than high freq reflection, do I want faced panels?


----------



## Ethan Winer

pierce,


> Has anyone tried to make a panel wider than 2'?


----------



## bpape

It will work fine to be wider - though I wouldn't get too ridiculous. If you need 2.5' or 3' wide - why not just turn the 2x4 panels on their side - cut to the appropriate width. Use the leftover on the inside to help tighten things up a bit.


There is no need to glue pieces together. For extra thickness, just frame them together or set them together and the framing/cloth will hold them in place. There is no need for them to be physically attached (or even touching totally) for them to function as the equivalent to 4".


----------



## piercedb

Thanks bpape and Ethan! The density study was quite interesting and helpful. I think its interesting that the panels can be set in the corner and still work without rigid mounting. That is good though, it means less work!


----------



## mbegala

I am in the process of acoustically treating my dedicated home theater. I'll be installing JM Insul-Shield on the walls and am looking for advice on locations for bass traps.


My room is 23 x 14. The ceiling slopes from the side wall to the ceiling starting at 70" up from the floor (see diagram below). The flat part of the ceiling is approximately 5' wide and 9' tall.


__

/ \\

| |

-------


The "barn" shaped walls are at the two ends (long dimension) of the room, one of which has the screen and front speakers, and the opposite wall contains the entry door as well as equipment and storage cabinets. Links to pictures of each can be found in my signature (sorry no URL's allowed as this is my first post).


On the front (screen) wall, there is 70" of vertical corner available to install a corner base trap. On the back (equipment) wall the vertical corners are occupied by cabinetry. Above the cabinetry there is an open area along the sloped portion of the ceiling.


With this limited space, I was planning on installing base traps in the front vertical corners, as well as above the cabinets on the back wall.


Is there an alternate placement that would work better?


Thanks...


Michael


----------



## bellm

I am in the process of deciding how acoustically treat my dedicated home theater.


My room is 20' 7" x 17' 1" with 9' drywall ceiling. I have Jamo D7 THX Ultra II speakers (7) and a Martin Logan Descent sub. There will be a 7' riser the width of the room along the back wall. front speakers will be mounted at 5' and surrounds and rears will be mounted at 6'. If I will use the room for 80% home theater and 20% music, what acoustic treatments should I install?




Thanks,


Michael Bell


----------



## ChrisWiggles




> Quote:
> what acoustic treatments should I install?



A combination of absorption and some diffusion, basically, like always.


I recommend F Alton Everests master handbook of acoustics.


----------



## Ethan Winer

Michael,


> what acoustic treatments should I install?


----------



## SevenOut

Great info, thanks for the help!


----------



## almd

I am building a room 14'x9'x28' with the ceilings sloping to 6'5" because it is a bonus room above the garage. the rest of the house is on the first floor. Screen wall and left wall are to exterior. Right wall is to attic. floor to garage. back wall to pretheater room.

I am concerned about sound in the rest of the house. I do not intend on watching loud movies into the wee hours of the night but I just don't want the attic or garage to act like a speaker box. I used to live in a poorly constructed apt and the guys TV upstairs would just echo in my bedroom so I am fearful of this. my AV guy says I don't need special insulation techniques...just using cocoon blowin insulation around the room and regular drywall with 2x4 framing. Anyone have experience with this. I was thinking about greenglue or quietrock but would love to save the money.

He is also recommending Sonance inwall/inceilings and sunfire sub. Do the Sonance inwalls allow a lot of sound out the back of these and can I still blow insulation over them?

One more random question. The HVAC guy has started to put the 3 vents along the right side of the room at about 5 feet off the ground. I just realized there has to be a grill or something on the wall there which will be ugly. Any ideas on where else to put them?

ARthur


----------



## ESGSeattle

I was hoping that someone could connect me to a good acoustic guy in Seattle. Any Ideas?


Thanks


Evan


----------



## ChrisWiggles

How good is good?


i.e. what are you trying to, and budgetwise?


----------



## ESGSeattle

My theater is built, at least the room and sound system. I have an inwall Triad system. However, I'm experiencing a lot of reflected sound. The room has just aquired carpet. I have seats on order. But, playing audio sounds like I'm waiting for a concert and the sound is bouncing around the auditorium. Well, I've been reading about others making their own panels. Sounds interesting. But, I want the job done right. I see you're in Seattle, what's your experience? Would you like to see my echo chamber?


----------



## ChrisWiggles

I'm just a DIYer, so if you want to go that route...


I've pmed you some other info though.


----------



## SuprSonik

Hi everyone, I am just about finished painting my theatre room and am ready to do some acoustic treatment. I needed a few things cleared up though...


When finding the first reflection points using a mirror, am I supposed to do this for just the Front R/L speakers, or the center/rears as well? I read that only the point up to where your ears are should be covered as well, does this mean I shouldn't put any rigid fiberglass above ear level or on the ceiling?


I'm not totally sure why the entire front wall needs to be covered too. It seems like no sound would be bouncing off that area. But if it's recommended, I'll do it. However, what about the area with the screen? Should I put the fiberglass up all over the wall first, then put the screen up? Or put the fiberglass around the screen (making the screen appear as though it's impressed into the wall?)


I'm planning on using 2" thick stuff, and I want to space it out from the wall a bit. What would be the best material to mount between the fiberglass and drywall? Wood?


Thanks for any help. I'm almost done with the painting, so I hope to get started on this soon.


----------



## BasementBob

SuprSonik:


> Quote:
> I'm not totally sure why the entire front wall needs to be covered too.



'Needs to' depends on how good you want it.

Have a look for SBIR and 'speaker radiation pattern'.

You can still hear music and lyrics if you are beside, or even behind, a speaker. So sound bounces off the front wall, and superimposes with the sound that you hear, perhaps cancelling out some frequencies.


I recently found this good explanation of Speech Intelligibility
http://meyersound.com/support/papers/speech/index.htm


----------



## Terry Montlick




> Quote:
> Originally Posted by *SuprSonik* /forum/post/0
> 
> 
> Hi everyone, I am just about finished painting my theatre room and am ready to do some acoustic treatment. I needed a few things cleared up though...
> 
> 
> When finding the first reflection points using a mirror, am I supposed to do this for just the Front R/L speakers, or the center/rears as well?



No. Only the front speakers need to have their early reflections absorbed. This is to keep the front sound-stage tight and accurate. Reflection is *good* for the surround speakers.



> Quote:
> I read that only the point up to where your ears are should be covered as well, does this mean I shouldn't put any rigid fiberglass above ear level or on the ceiling?



Not necessarily. It depends on how much absorption your room needs. As for the ceiling, sometimes there are early reflections which need to be absorbed there. This depends on the directivity pattern of your speakers, as well as how they are place.



> Quote:
> I'm not totally sure why the entire front wall needs to be covered too. It seems like no sound would be bouncing off that area. But if it's recommended, I'll do it.



It may not be absolutely necessary. If you know beforehand that your front speakers do not significantly radiate at medium to high frequencies toward the screen wall (considering toe-in!), you don't need it. It is always a good safety measure, however. In commercial cinemas, where the speakers are located behind a perforated screen, front wall absorption is used largely to kill reflections from the screen back towards the front wall.


Absorption on the front wall also follows the live-end dead-end model (room is live in back, dead in front), which works well for home theater surround sound. The front wall is also generally a convenient, available area for absorption.



> Quote:
> However, what about the area with the screen? Should I put the fiberglass up all over the wall first, then put the screen up? Or put the fiberglass around the screen (making the screen appear as though it's impressed into the wall?)



If you are using an ordinary non-perforated screen, you don't need fiberglass behind it.



> Quote:
> I'm planning on using 2" thick stuff, and I want to space it out from the wall a bit. What would be the best material to mount between the fiberglass and drywall? Wood?



You could space it out with furring strips. Spacing the absorption from the wall enhances low frequency performance.


Regards,

Terry


----------



## bpape

Just for clarity, all 3 front speakers should have reflection points covered - not just L and R.


Also, I've found in some cases that even without a perforated screen, having some 3lb fiberglass behind the screen tends to help focus things from a center image standpoint. I don't worry about this too much unless the person is also going to be doing a lot of music listening - especially 2 channel. However, this is WAY less important than taking care of the reflection points elsewhere IMO.


----------



## BasementBob

bpape


> Quote:
> However, this is WAY less important than taking care of the reflection points elsewhere IMO.



Yep.

It's a time and volume thing.

The volume/loudness/signal (speaker radition pattern) out the front of the speakers is louder out the front than the sides.

Reflections off the side walls (and floor and ceiling) arrive much closer in time to the dirrect sound than any reflection off the front wall.


----------



## KWhite

"Spacing the absorption from the wall enhances low frequency performance."


Do you have any absorption coefficients for 1" OC 703 mounted with 1" spacing off the wall?


----------



## Ethan Winer

K,


> Do you have any absorption coefficients for 1" OC 703 mounted with 1" spacing off the wall?


----------



## SuprSonik

Thanks guys, I think I've got it now. If I have enough spare fiberglass left over, I'll put it behind the screen like bpape suggested. I've always preferred headphones for music, so this is mostly home theatre I'm talking about here.


The only place I've been able to find OC703 is this place , and I'll have to order in bulk of 96ft, and it will have to be shipped to me. I'd prefer to avoid this problem if possible. I know John Manville makes a similar material called Spin-Glas, but I haven't been able to find that locally either. Do you know of any other brands that make rigid fiberglass so I could check on those too?


----------



## bpape

CertainTeed makes a 3lb/cu ft equivalent as does Johns Manville


96sq ft is a pretty standard purchase for 1" - that's half a carton (12 pcs). For 2", it's a whole carton.


You can get less but by the time you pay the shipping, the cost per piece will kill you if you're only buying a couple of pieces. Shipping cost on something that size is purely by size - not weight. IOW, you'll pay the same amount to have 2 pcs of 1" shipped to you as you will 12 pcs.


----------



## SuprSonik

I see...thanks. I have one more question; which is best for this type of use? "Plain", "Foil Scrim Kraft", or "All Service Jacket"? I decided on going with 1" because I don't want it to sound too dead. Here's the specs of Plain vs FSK vs ASJ according to Knauf's site:



---------------125hz 250 500 1000 2000 4000 NRC

Plain 1" (25mm) .08 .23 .62 .88 .96 .99 .65

FSK 1" (25 mm) .21 .63 .84 .93 .51 .22 .75

ASJ 1" (25 mm) .15 .71 .65 .82 .41 .16 .65


(Sorry, it's hard to get the frequencies to line up with the numbers.)


I'm not sure which frequencies I want the most absorption at for the best results?


Wouldn't the foil material reflect sound rather than absorbing it? Or am I confused? I was planning on wrapping it in some cloth material.


FSK and AJS seem to be better at low/mid frequencies, while plain is better at higher frequencies. Should I assume that plain is the best choice then?


----------



## stef2

Hi everyone. I live in Quebec, Canada:



Around here I'm having a hard time finding OC 703 or OC 705 to treat my home theater.



At the local Home Depot, they sell some Roxul Safe and Sound Mineral Wool which is 3 inches thick and 2.5 pcf. The absorption coefficients for this material looks a lot like the ones listed for OC703 (2 inches thick), according to bobgolds.com tables (The only significant difference I see is more absorption at 125Hz).


I've worked with this material in the past for wall insulation. To me it looks more like normal (not rigid) wool than rigid fiberglass.


Does anyone know if I can use those roxul "panels" instead of OC703 for every well described OC 703 usage? From an absorption point of view, they seem to be quite equivalent (am I right?). But if I use the Roxul Mineral Wool, lets say to treat first reflection points ,my whole front wall or to build corner bass traps, is there any special thing I must do (for example, should I compress it? Should I space the panels from the walls or leave them flat on the wall since Roxul seems to absorb more of the low freqs?)


To summarize, how can I get the OC703 effect while using the Roxul Panels?


Your help will be greatly appreciated...I've been reading this whole thread with a lot of interest!



Stephane Olivier


----------



## bpape

Having additional absorbtion at 125Hz is not generally a problem. Also, the difference between the 2 sets of specs is pretty insignificant - even at 125Hz.


I'd plot out what the room needs from a decay time perspective and plug in those values. I doubt you'll have any issues using it.


----------



## tonybradley

I'm on vacation this week and have been reading a lot of the acoustic threads. I can't remember where I read this, as it may have been a link from a link from a link. Anyway, for Bass Traps, I read that you could purchase Rolls of Fluffy insulation (didn't matter which type, i.e. R13, R19, R25), stack them three high with the plastic wrapping on, and cover them.


Will this work as an effective bass trap? If so, does it matter which thickness I purchase or if I buy them faced or unfaced?


----------



## ChrisWiggles

that would work ok, the reason to leave it in the packaging is because it's compressed down to a lot denser, similar to the density of fiberboard that is often discussed here as the effective and economical route to treatments.


On the other hand, you could just buy batts of fiberboard and leave the batt in the corner if you wanted, too. Don't think the cost would be too different, and then if you did want to make some absorbing panels for reflection points etc to tame the RT60 time of the room, you could use some of those boards for that. Fluffy fiberglass rolls insulation won't be useful for that.


----------



## tonybradley

Thanks Chris. I'm definitely going to either use 1" or 2" OC703 Rigid Fiberglass for the First Reflection points. I've read quite a bit on here and it appears the rule of thumb is to use the 1" OC703 panels over the 2"?


I'm trying to decide now whether to use Rigid Fiberglass boards for the Bass Traps, or the rolls of fluffy insulation.


----------



## Terry Montlick




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Thanks Chris. I'm definitely going to either use 1" or 2" OC703 Rigid Fiberglass for the First Reflection points. I've read quite a bit on here and it appears the rule of thumb is to use the 1" OC703 panels over the 2"?



If I might jump in, either 1" or 2" will work for early reflections. 2" gives you some addition absorption toward the bass because of the added depth. However early reflections are strictly higher frequency effects, so bass absorption doesn't matter.


Regards,

Terry


----------



## tonybradley

Thanks Terry. So, as long as I use some Bass Traps in my theater for the lows, I should be OK with 1" OC703 panels for my first reflections?


----------



## Dennis Erskine

...that's where doing some models is helpful. Early reflections are a higher frequency issue; but, we also find most residential sized rooms will have a bump in decay times in the 250 to 500Hz range. So if that will be an issue, that can be part of an overall strategy to address both issues.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> ...that's where doing some models is helpful. Early reflections are a higher frequency issue; but, we also find most residential sized rooms will have a bump in decay times in the 250 to 500Hz range. So if that will be an issue, that can be part of an overall strategy to address both issues.



I agree, Dennis. And measurement can trump models. I recently measured a built but not treated room which had extremely good bass through mid-frequency reverberation times -- not so good high frequency characteristics.


Turns out that the room had an acoustical tile ceiling, which would explain the response I measured in this bare-walled, carpeted room. Now, I didn't have the specifics on the tiles, or how they had been installed. A model would have been a shot in the dark.


But the measurements told me what I need to know for treatment. This room is going to get 1/2" thick fiberglass absorption on the walls. Any thicker, and we run the risk of deadening the mid-range too much.


Regards,

Terry


----------



## PAD

Never purchased from them, but am going to buy some 703 material:

http://www.insulationworld.com/default.asp


----------



## kjohn

I am a dedicated audiophile with a home theater I listen to music and movies in this room but if I had to go one way or the other I would lean to the music side for sound treatment. I had my room done by a contractor with no sound treatment accept thick velvet curtains on the front wall around the screen covering 95% of the front wall I have become so confused with what to do I have given up for now on doing anything for sound treatment and reading this board has done nothing but to confuse me even more is there a simple way to figure out what I can atleast start with for room treatment and a source to buy them ( I'm thinking sound treatment panels for mid to upper frequency) with out a lot of technical jargon can you guys give me some basic suggestions I do have pictures of the room if you would like me to e-mail them to you











Only recently after reading many many hours on this board and other material have I somewhat got an understanding of the terms and practices of proper treatment and still after thinking I got it I read Dr Dennis and Dr Terry's post and I feel dumb again, I call them doctors because if you ever had a doctor explain something in medical terms sometimes you can go away feeling am I going to die or did he say maybe







I myself sometimes when talking to people about my profession or interest get carried away with terms that someone else in my field can understand but someone who does not might say is he on prozac. So to summarize HELP!! in terms I can understand and knowing it won't be perfect


----------



## Terry Montlick




> Quote:
> Originally Posted by *kjohn* /forum/post/0
> 
> 
> I am a dedicated audiophile with a home theater I listen to music and movies in this room but if I had to go one way or the other I would lean to the music side for sound treatment. I had my room done by a contractor with no sound treatment accept thick velvet curtains on the front wall around the screen covering 95% of the front wall I have become so confused with what to do I have given up for now on doing anything for sound treatment and reading this board has done nothing but to confuse me even more is there a simple way to figure out what I can atleast start with for room treatment and a source to buy them ( I'm thinking sound treatment panels for mid to upper frequency) with out a lot of technical jargon can you guys give me some basic suggestions I do have pictures of the room if you would like me to e-mail them to you



Hi kjohn,


Lacking acoustical measurements of the room (which I recommend because it is hard to do treatment without first having a diagnosis), I would start by putting 1"-2" thick acoustical panels at the 1st reflection points on the side walls. This is the equivalent of an acoustical vitamin pill for your room.







Do a web search for "fiberglass acoustical panels."


Regards,

Terry


----------



## kjohn

Terry thank you now I live in Canada is there someone here that you know of that can come out and give me a measurement.


----------



## Terry Montlick




> Quote:
> Originally Posted by *kjohn* /forum/post/0
> 
> 
> Terry thank you now I live in Canada is there someone here that you know of that can come out and give me a measurement.



I recommend purchasing ETF, a product developed and sold by a fellow Canadian, Doug Plumb. This will perform a variety of acoustical measurements. A professional can then help you interpret these measurements, or you can simply post some graphs on this forum and see what responses you get. Our acoustical analysis software and procedures are now 100% compatible with ETF. So we can do our own detailed analysis, and even issue Alpha Certification, just from the ETF files.


Regards,

Terry


----------



## warrenP

Hey folks,


Currently I'm in the planning stages of our next theater. I have decided that we will be going with a fixed 2.35:1 screen. The width will end up at 10 foot, which will force me to place all three front speakers behind the screen. (The room is actually 16 feet wide, but there is a concrete foundation angle where the right front would go, so to be equal the L/R fronts will be at the edges of the screen).


Due to the depth of the room, the speakers are essentially in the room (a storage room) that is behind the screen. I need to build 'back' into that room versus build out into the theater space.


Would you frame the front wall with three holes, the exact size of the speakers, and treat the remainder of the wall? If so, what is the ideal treatment in that scenario?


thanks.


----------



## stef2

From reading the different tables about panels density and absorption coefficients, I wonder what would be the effect of compressing the material to make it denser.


For example, if I use Roxul Safe'n Sound rockwool, which is three inches thick, and has a density of 2,5 pfc, and I compress it to get half the original thickness, my conclusion is the density should be doubled. Am I right? I would then get 5,0 pfc, very close to the OC705 density. Is my assumption right? My panel would be twice as dense, but half as thick. Would that change its absorption coefficients?


And what would then be the best way to absorb bass? the same amount of material uncompressed or compressed to half its original thickness?


Probably my questions are not very clear, but What I'm wondering about is the difference (or relation) between density and thickness. Can anyone answer my question(s).


The reason I'm asking this is that I want to make my sidewall panels as thin as possible...and the roxul wool I've got is quite easily compressible (lets say using a metal grid like I've seen once on this forum)...



Stephane Olivier


----------



## bpape

Yes. It would be twice as dense but half as thick. Would that change things? Yes it would. What would the result be? Impossible to say without testing it.


The material's ability to absorb bass frequency depends on a combination of thickness, density, and placement from a boundary or boundaries. They all work together. Can you get good bass absorbtion from 12" of 1lb/cu ft. material? Sure. Can you use 6" of 703 instead of 4" of 705? Sure - might even do better.


There is a point though where you just need a certain amount of thickness no matter what. I wouldn't try to get any kind of even relatively deep bass absorbtion with anything less than 3" thick - 4 to 6" is better no matter the material.


Density basically determines how much it will slow down larger waves. Thickness determines how much of a wave can be contained within the absorbant material. Distance (spacing) determines what part of the waves are in the absorbtion.


These are all velocity absorbers - not pressure absorbers. At a wall boundary, the velocity is zero - not a good place. As you move farther out, the velocity is higher - so the absorbers are more effective. Corner mounting is desirable for a couple of reasons:


- They are at the end of ALL of the frequencies and will grab a bit of everything.

- When you straddle a corner, you get almost a foot of airspace behind them (assuming 2' wide panels)

- You are exposing the material to both the length and the width of the space (assuming vertical wall/wall corners). For your 2' of material, you're actually covering 1.4' of the front wall and 1.4' of the side wall.


----------



## weight

I will be using 703 oc 2" mount on the wall in a 2by 2 frame cover with fabric then using 1" trim on the outside to hold the fabric and the 703 in place also could this behave maybe a little like a diffusor and absorber since i'm using some wood on the outside of the panel.


----------



## bpape

Framing the panels can provide some deflection - not really diffusion - unless they're spaced at controlled intervals in relation to their width and height. Then, the whole array could provide some diffusive properties.


----------



## myfipie

Weight,


You may want to think about drilling holes in the wood so sound will get in the sides also.. Bryan will say that is only a bonus, but that is kind of like my girlfriend saying she saved us money because the shoes where on sale.


----------



## bpape

???


More like the other way around. Why buy them just because they're on sale? If you do the analysis based on the surface area of the panel, what you get from the sides IS extra - and maybe not desirable.


----------



## myfipie

maybe not desirable?? Not so sure about that. Unless you think you could do to good of a job and knock down to much. For a bass trap you just can't have to much.


----------



## bpape

That's a nice thing to say but you actually can have too much - though it's very tough. The issue is that you're also exposing more HF absorbtion to the room which may not be desirable. OTOH, it may be just fine.


Realistically, the amount of square footage you gain by poking holes is debatable in regard to the overall picture. In most cases, you'd probably be fine doing it if you want to spend the time. How much will you really get? Well let's see. If you poke a 2" dia hole every 6" (that's a LOT ) on both sides of an 8' tall frame, that would give you about 30 holes at approx 3.1 sq in each. That's about 94 sq inches. 144 sq inches in a sq ft so you're getting about an extra .6 sq foot of exposed area from 16 linear feet of edge 4" wide. The panel itself yields 16 sq ft (2' wide, 8' tall) so you're gaining an extra 3.8%


----------



## myfipie

Guess you would have to build it to see if 6" is "a lot"... I think it is more like 3 inchs apart and 3 inch holes.. Now your talking more in the 10% range.. I see where you are going with that Bryan and most people just have a hard enough time building the frame without cutting there finger off!! ha ha ha


----------



## bpape

Yeah. Absolutely. If you really want to expose the sides, just get out your trusty router and route out the center 2" all the way down leaving some 'braces' every couple of feet. If you look at the design on Ethan's panels, that's providing some serious side exposure. Now with those, at least the numbers that are posted that you figure with include that side exposure so you can plan accordingly when doing your calculations.


BTW, if you cut 3" holes in a 4" panel side, you're getting pretty skinny on the outside (1/2"). And 3" holes on 3" centers will just exactly meet each other. I assume you meant 3" in between the edges of the holes. I was just throwing out some basic numbers to show what drilling 30 holes in the sides would do as far as surface area compared to the face itself.


----------



## ebr

Okay, after reading this entire thread (I think I'm now cross-eyed) you guys have convinced me I need to consider some bass trapping in my new room. Two questions:


1) My sub will be in one of the front corners (please save the "OMG - don't put that thing in the corner" argument as this is really my only option







). Will it be a good idea to build a corner trap above the sub - basically spanning the corner with fiberglass from the top of the sub to the ceiling?


2) My new room will have a cubby/alcove much like this one:










Would it be helpful to put a trap in that thing - or is the fact that it is not "connected" to the main boundary walls going to negate the effectiveness of a trap there? I was thinking that I could just build out the rear wall of the cubby with a couple of inches of fiberglass that is another couple of inches from the actual wall giving me a kind of panel trap across the back of the cubby hole area. Make sense?


----------



## myfipie

I think putting a trap back in that area would be great. Though you are going to need more then just one..


----------



## bpape

Yes. That would be good. Also put one in the corner on the other side left to right at a minimum. You'll probably need more as Glenn alluded to but it's a start - then you'll be hooked.


----------



## ebr

Great - is the way I described building it correct?


kinda like this (view from top):

Code:


Code:


back wall    -------------
air space    x           x
fiberglass   -------------
             |           |
             |           |
             |           |

Also, do you think the corner trap over the sub is a good idea?


----------



## swithey

ebr,


I KNOW bpape will tell you he would like at least 12" of total depth for this trap. He'll also probably tell you to put in 4" to 8" thick material. I'm sure Bryan will ring in soon










I only say this because he's helping me with my room. I'm going with dual 2' deep x 2' wide monsters in rear of the room (which is about the exact same size as yours) behind a hidden wall.


Good luck on the build







Oh, and great looking room!! I'm going to steal your light tray idea for mine -- hope you don't mind.


Steve


----------



## myfipie

_


2 feet of rigid fiberglass???? Do you have some kind of 5hz problem we should know about... ha h aha_


----------



## swithey




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> 2 feet of rigid fiberglass???? Do you have some kind of 5hz problem we should know about... ha h aha



Actually, Bryan is talking about a 2' wide x 4" (might be 8") thick piece of a cotton material. Well put it floor to ceiling. Hell, it could be a small baby bed matress for all I know







We're still discussing what exactly he wants to put inside. All I know is it will go VERY low and just do wonders for the room.


Steve


----------



## bpape

Actually, 2' deep is only equivalent to the 1/4 wave of somewhere around 125Hz. Originally I had planned to do a REAL bass trap but we just didn't have the depth and also didn't have the luxury of doing just that since these are pretty much the only 2 bass absorbers we'll have in the room due to aesthetic concerns, no risers, etc. There will be cloth covered panels on all of the wall surfaces - except the back wall which is false (smaller panels) so sealed membrane absorbers are out. One rarely has an option like this in an existing space but when you do, it's nice to take advantage of it. The fill will likely be a mix of materials. I'm still doing the calculations.


In addition, once the room is mostly done and we take some measurements, we'll likely add a sealed membrane on the bottom 1/3 of the space between these 2 beasts tuned appropriately. The upper is still being decided. The whole back wall is false and about 2' deep to house the rear surrounds, the bass absorbers, and eventually a second HSU VTF3.


I wish there was some way we could get some bass control other places in the room but it's just not feasible with the design constraints. We'll make the most of what we have to work with.


----------



## mleineke




> Quote:
> Originally Posted by *SuprSonik* /forum/post/0
> 
> 
> I see...thanks. I have one more question; which is best for this type of use? "Plain", "Foil Scrim Kraft", or "All Service Jacket"? I decided on going with 1" because I don't want it to sound too dead. Here's the specs of Plain vs FSK vs ASJ according to Knauf's site:
> 
> 
> 
> ---------------125hz 250 500 1000 2000 4000 NRC
> 
> Plain 1" (25mm) .08 .23 .62 .88 .96 .99 .65
> 
> FSK 1" (25 mm) .21 .63 .84 .93 .51 .22 .75
> 
> ASJ 1" (25 mm) .15 .71 .65 .82 .41 .16 .65
> 
> 
> (Sorry, it's hard to get the frequencies to line up with the numbers.)
> 
> 
> I'm not sure which frequencies I want the most absorption at for the best results?
> 
> 
> Wouldn't the foil material reflect sound rather than absorbing it? Or am I confused? I was planning on wrapping it in some cloth material.
> 
> 
> FSK and AJS seem to be better at low/mid frequencies, while plain is better at higher frequencies. Should I assume that plain is the best choice then?



I did not see a response to this reply. I am also curious about this.


Thanks.


Mark


----------



## Terry Montlick




> Quote:
> Originally Posted by *mleineke* /forum/post/0
> 
> 
> I did not see a response to this reply. I am also curious about this.
> 
> Thanks.
> 
> Mark



Use one of the faced insulations if you do not want high frequency absorption. These get largely reflected off the facing. In treating early reflections, for example, which will be at medium to high frequencies, you would *not* use it.


Regards,

Terry


----------



## bpape

Exactly. The facing will reflect the mids and highs but bass the bass. Think about it logically - if you're worried about bass getting out of your room through drywall, this kraft paper has no shot at stopping it.


The FSK or FRK is fine - no need for FSJ - not even sure how that would work - never tried it. Also, what you need absorbed is part of the analysis that you do or hire someone to do for you that identifies all of the things in the room - floor, wall construction, windows, doors, furniture, people, etc. coupled with what you're using the room FOR (HT, 2 channel, recording studio, etc.) to determine how much absorbtion you need at each frequency range and where is the optimal place(s) to put it.


----------



## out2lnch

Since this appears to be the best place to ask: has anyone looked into Enermax rigid fiberglass ( http://www.emcobp.com/en/02/p_02_01_01.aspx?p_prid=22 ). It has a foil facing and is said to be 14.5 lb/ft^3 and is made for sound applications.


Wondering if this would make a decent choice, covered in a porous material, for taming slap echo and the like (foil side against wall of course) and maybe used in combination with fluffy fibreglass/mineralwool to make bass traps.


For example, what about faux columns in the corners of the room made out of four pieces of rigid glass with a top and bottom, and filled with fibreglass/wool, and slid into the corner and covered with fabric to blend into the decor? It would then span the corners like is recommended, but would be more substantial than just 1 sheet put at an angle.


Probably already been raised somewhere, but I couldn't find it so I thought I'd ask.


Great source of info. by the way.


----------



## Ethan Winer

> Wondering if this would make a decent choice 
what about faux columns in the corners of the room made out of four pieces of rigid glass with a top and bottom, and filled with fibreglass/wool, and slid into the corner and covered with fabric to blend into the decor?


----------



## out2lnch

I may try this myself, but am hesitant to go through the trouble if it's likely not worth it (OC 703/705 aren't available around here as far as I can tell). I realise the absorption data aren't listed, but would it likely be decent for first reflections and/or high feq. absorption (and maybe a little mid-range if only 1 panel thickness is used)? I imagine that the materials are probably similar in many of these products, but would this density be too high for this sort of application, or is there such a dramatic difference that it could range from "fantastic" to "piece of ___" in the absence of said absorption data? I figure, even if it's not as good as the OC stuff, it may be easier for some people to find (Canadian HD stores).


Thanks.


----------



## bpape

I'd be very leary of using something with that high a density for early reflection point absorbtion. Even something like 8lb can cause high frequencies to just skip off instead of being absorbed.


Without numbers it's hard to say but it might very well do a decent job with the foil toward the room as a bass absorber.


----------



## out2lnch

I guess I should be looking for something else for this then. When I get around to tackling bass absorption maybe I'll pick up a sheet and see what happens.


Thanks for the feedback.


----------



## Terry Montlick




> Quote:
> Originally Posted by *out2lnch* /forum/post/0
> 
> 
> Since this appears to be the best place to ask: has anyone looked into Enermax rigid fiberglass ( http://www.emcobp.com/en/02/p_02_01_01.aspx?p_prid=22 ). It has a foil facing and is said to be 14.5 lb/ft^3 and is made for sound applications.



The link specs said it was a wood product, not fiberglass. It was described as a being for noise isolation. It looks similar to Homosote, which has no value as a sound absorber. For a sound isolator, nothing beats sheetrock for the price!


Regards,

Terry


----------



## out2lnch

Oops, missed that. Just assumed it was fibreglass-based by the "look" of it at the Depot. Guess I'll hit the phone book and start calling around for the OC boards, it has to be here somewhere....


----------



## myfipie

Out2inch,


Try SPI if you have one close to you.


Glenn


----------



## vfrjim

Ethan (or other experts)

I am currently selecting my ceiling tiles for my theatre and have selected a USG one, here is a link to it's specs: http://www.usg.com/products/ViewProd...ing_Panels.htm 


It has a .75 NRC, does this mean it has a better accoustic rating then using drywall? Any benefit of the perfed (.75) over the non-perfed (.60) tiles?


Thanks for any and all info.


----------



## Terry Montlick




> Quote:
> Originally Posted by *vfrjim* /forum/post/0
> 
> 
> Ethan (or other experts)
> 
> I am currently selecting my ceiling tiles for my theatre and have selected a USG one, here is a link to it's specs: http://www.usg.com/products/ViewProd...ing_Panels.htm
> 
> 
> It has a .75 NRC, does this mean it has a better accoustic rating then using drywall? Any benefit of the perfed (.75) over the non-perfed (.60) tiles?
> 
> 
> Thanks for any and all info.



0.75 is good for a 5/8" acoustic ceiling tile. A 1" tile will yield greater absorption. But this number doesn't tell you much, since it does not break down the absorption by frequency. It also assumes an E-400 mounting - a 400 mm (16 inch) space above the tiles.


It is both better and worse than drywall. Much better at absorbing sound within the theater, and much worse at keeping sound in or out of the theater.


Regards,

Terry


----------



## vfrjim




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> 0.75 is good for a 5/8" acoustic ceiling tile. A 1" tile will yield greater absorption. But this number doesn't tell you much, since it does not break down the absorption by frequency. It also assumes an E-400 mounting - a 400 mm (16 inch) space above the tiles.
> 
> 
> It is both better and worse than drywall. Much better at absorbing sound within the theater, and much worse at keeping sound in or out of the theater.
> 
> 
> Regards,
> 
> Terry




So, does this mean that I will need less acoustic treatments on my walls? Keeping sound within the room is not a goal of mine, so that is OK to me. Sound quality is more important. Also, I am planning to mount these tiles with the CeilingMAX system (for headroom constraints) so that 16" clearance above them will not exist, wish it could though.


Also, planning on R-25 insulation above the tiles, does it do anything for sound performance in addition to the USG tiles?


Thanks


----------



## JamesE

I got mine from a roofing wholesaler that sold Owens Corning roofing materials. If you can get it thrown on the next truck from the factory, shipping won't be that expensive.


----------



## bpape

The insulation above will provide some extra control in the lower frequencies and is definitely recommended. The drop ceiling will provide some absorbtion in-room in the mids and highs but not much in the bottom end. You'll still need to control the bass but watch how much other HF absorbtion you have in the room so you don't overdo it in the highs.


----------



## Terry Montlick

With absorption above, you still cannot ignore the walls. At a minimum, they will need treatment at early reflection points between front speakers and seating area. This can be either absorption or diffusion. Also, be careful that opposite, parallel wall surfaces are not bare. Again, absorption or diffusion is required.


All absorption on the walls is not a good idea in light of the ceiling absorption, and mostly diffusion should probably be used. There should be sufficient vertical diffusion so that the sound hitting the walls will scatter towards the ceiling. Otherwise, the reverberation may be uneven and long, with a slower decay horizontally (between wall surfaces) than vertically (between ceiling and floor).


Regards,

Terry


----------



## RicosRevenge

Story time... sorry, I'm excited and ready to get to work!


After an exhaustive search all over the Dallas area with no luck, I stopped by a large HVAC place 2 buildings down from my office and asked about duct board. I made a list thanks to Bob Gold's site that included (9) Popular Rigid Fiberglas boards from: J/M, OC, Certainteed and Knauf.


They didn't have any of them but they had OC 475 EnDuraGold in 4'X10'X1"


I came back to my office and tried to look it up and Bob's list didn't include it... so I did a search and in page 14 of this thread there was mention made of it and the poster said that the Absorption Properties were not good. I continued to searched the OC site and found the specs on the product.

*Product------------- thickness 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC*

Average of 9 Products--1" (25mm) 0.08 - 0.26 - 0.64 - 0.89 - 0.97 - 0.99 - 0.69

Type 475 EnDuraGold---1" (25mm) 0.08 - 0.19 - 0.69 - 0.94 - 0.99 - 0.98 - 0.7



SCORE!! That is perfect! The properties are dead on.


I was going to buy it from the HVAC place at $45 a sheet, but instead the parts guy did me a favor and called in an order for me at another place on the other side of me office and I got it for about $30 a sheet. All that looking and it was right under my nose...


----------



## swithey

Ricos,


I live in Dallas also and found a few other places that sell fiberglass that may work for you too. Check out these two threads:


This place sells Mineral Wool
http://www.avsforum.com/avs-vb/showt...as#post5847246 


Check out this post and the one a few down from this one for Insulshield (and the like)
http://www.avsforum.com/avs-vb/showt...&post6017867 


Let me know how it goers. I'm going to need to purchase some around the end of the year.


Steve


----------



## ebr

Not sure I want to re-flame this debate, but I am interested in the experiences of those who have used the "first reflection point" method of acoustical treatment for theater rooms with multiple rows of seating.


I used this tool --> http://www.avsforum.com/avs-vb/showthread.php?t=604400 (thanks Easley) to model just some of the first reflection points for my setup and pretty much found that I would need to cover most of the side walls (at ear level) with absorption (this is what I've always done as my first room was designed by DE).


I got reflection points ranging from 45 to over 110 inches out and this tool is calculating precise points. In reality, the speaker doesn't emit sound from a precise point - it is from a cone ranging from a few inches to several inches across. In addition it doesn't radiate in a straight line - it radiates in a sphere - producing a larger and larger area of "affected" sound waves the further away from the speaker you get.


Accounting for this broader band of sound as well as the range for all the seats, it seems like trying to target absorption at exact reflection points for such a setup of multiple speakers and seating would be futile and just end up with basically the same setup I've always had - absorption all along the side wall at ear level.


For those of you who have treated your rooms with this "first reflection" method - have you found the same thing, or did you target just a couple of "sweet spots" for your treatments?


----------



## vfrjim

Terry, at one of my midpoint areas(along my long wall) is a door, is there a way to treat a door to "diffuse" the sound?


Thanks for all your help.


----------



## Terry Montlick




> Quote:
> Originally Posted by *vfrjim* /forum/post/0
> 
> 
> Terry, at one of my midpoint areas(along my long wall) is a door, is there a way to treat a door to "diffuse" the sound?
> 
> 
> Thanks for all your help.



Sure. Just build some diffusers onto the door. Here is a rather fancy one made of hardwood that I designed for a client:











Those are RPG Skylines on either side of the door. They might just as well have been fastened to the door, except for the aesthetics of the Skylines, which didn't go with the room. So we buried 'em behind some nice Guilford fabric.


Regards,

Terry


----------



## bpape

ebr,


Yes. You can end up with a lot of points - specifically one for each seat for each of the LCR speakers. I personally don't generally absorb reflections deliberately from the surrounds. I prefer to leave the surround field more lively. This does not mean that there is no absorbtion in the rear half and rear wall - just more judicious and more broadband. Some will disagree with that. Works for me.


----------



## ebr

Thanks Brian. I was only modelling LCR as I knew we didn't want to mess too much with the reverberant field for the surrounds. I guess I was just a little surprised to find that the two supposedly different methods of treatment - really weren't *that* different. But, that's a good thing, I guess







.


----------



## Terry Montlick

I'm with Brian. I only deal with LCR early reflections. Surround sound reflections are not an issue for home theaters, as they do not affect the front sound stage.


- Terry


----------



## WoodMonkey

Hey guys. I was wondering what you folks thought about acoustic panels (for absorption) being made out of a solid panel (mdf or ply) with a layer thick carpet padding, covered with some fabric. I am going for a nice clean look and I want to save money. Is that too much to ask??










What do you think about that idea?


----------



## Terry Montlick




> Quote:
> Originally Posted by *WoodMonkey* /forum/post/0
> 
> 
> Hey guys. I was wondering what you folks thought about acoustic panels (for absorption) being made out of a solid panel (mdf or ply) with a layer thick carpet padding, covered with some fabric. I am going for a nice clean look and I want to save money. Is that too much to ask??



Yes.










Go with 1-inch or more Johns Manville Linacoustic or other roll-type fiberglass. It is not that expensive, and is much more effective than thick carpet padding.


- Terry


----------



## myfipie

Using carpet padding as a acoustic panel is not the right thing to do... If you want to save money that is fine, but use mineral wool or oc 703. Treating your room with products that do not have any testing at all is really flirting with disaster. Companies like ours and others spend big money to test our products in a lab. This is so people know what they are using.

Ask yourself a question, would you buy a speaker with no testing or build a speaker without some kind of proven method behind it? Your room acoustics are more important then any other gear you have to achieve good sound.













> Quote:
> Originally Posted by *WoodMonkey* /forum/post/0
> 
> 
> Hey guys. I was wondering what you folks thought about acoustic panels (for absorption) being made out of a solid panel (mdf or ply) with a layer thick carpet padding, covered with some fabric. I am going for a nice clean look and I want to save money. Is that too much to ask??
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> What do you think about that idea?


----------



## RicosRevenge




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> ... flirting with disaster.



LOL! That was the name of my race boat.


Woodmonkey - man from one "non-expert" to another. Call a couple HVAC installers and ask them what kind of 1" fiberglas duct board they use. Chances are it will be Owens Corning or Certainteed. Then ask who their supplier is.


This stuff is EXTREMELY easy to cut to size and cover. A little spray glue and some staples and you are done. Put some finishing nails in the wall at a slight upward angle and push the pieces into place. The end.


I'm sure I'll get blasted for a non-technical approach and that the acoustic coefficients of the spray glue will discombobulate the space-time continuity or something like that... but it is very effective.


----------



## Terry Montlick




> Quote:
> Originally Posted by *RicosRevenge* /forum/post/0
> 
> 
> LOL! That was the name of my race boat.
> 
> 
> Woodmonkey - man from one "non-expert" to another. Call a couple HVAC installers and ask them what kind of 1" fiberglas duct board they use. Chances are it will be Owens Corning or Certainteed. Then ask who their supplier is.
> 
> 
> This stuff is EXTREMELY easy to cut to size and cover. A little spray glue and some staples and you are done. Put some finishing nails in the wall at a slight upward angle and push the pieces into place. The end.
> 
> 
> I'm sure I'll get blasted for a non-technical approach and that the acoustic coefficients of the spray glue will discombobulate the space-time continuity or something like that... but it is very effective.



Yes, the spray glue *will* in fact discombobulate the space-time continuum, but a little bit works quite nicely.










- Terry


----------



## RicosRevenge

^^^ That wasn't as bad as I thought...


----------



## myfipie

"LOL! That was the name of my race boat."


Sailboat??? What kind?? I have spent many of days racing sailboats. boy I miss those days.


----------



## myfipie

"I'm sure I'll get blasted for a non-technical approach and that the acoustic coefficients of the spray glue will discombobulate the space-time continuity or something like that... but it is very effective. "


Not at all.. It is a matter of looks, time and if you want to know what is going into the room..


----------



## RicosRevenge

myfipie... I raced offshore powerboats on the APBA Pro-Series circuit. I have a 34' Eliminator V-bottom with twin 500 HP Mercs in Factory 2 class, she ran 96.5 MPH on radar. I love going fast on the water (Top speed 165 MPH in a 46' Skater cat with twin 1400 hp Sterlings).


Thanks for not lighting me up on my lay-person's description. I find that there are many times when the incredible knowledge on this forum can overpower the novice. If I was given a more direct approach, it would have taken me MUCH less time to track down the stuff I needed. BobGold's co-efficient charts are key!


----------



## storminorm

I did a search for Auralex sound panels but received no hits. My HT is 18x26 9' ceilings with speakers behind screen, 2 long side walls and back wall is a patio door with 2 side windows which are covered with heavy curtains. I'm planning on ordering Sonoflat panels from Auralex, local dealer, but I'm wondering if anyone has any experience with placement and installation? Behind my screen is a 2' x 12'

cavity for my 2 fronts, center, and sub, should I place panels behind the screen, behind the speakers? Where would you put them on the side walls. Side walls from floor to ceiling are 7'6" then a 18" soffit = 9', floor is carpet, wall with screen covered with black fabric. Can anyone help me sort this out? I definitely need bass traps.


----------



## magking




> Quote:
> Originally Posted by *storminorm* /forum/post/0
> 
> 
> I did a search for Auralex sound panels but received no hits. My HT is 18x26 9' ceilings with speakers behind screen, 2 long side walls and back wall is a patio door with 2 side windows which are covered with heavy curtains. I'm planning on ordering Sonoflat panels from Auralex, local dealer, but I'm wondering if anyone has any experience with placement and installation? Behind my screen is a 2' x 12'
> 
> cavity for my 2 fronts, center, and sub, should I place panels behind the screen, behind the speakers? Where would you put them on the side walls. Side walls from floor to ceiling are 7'6" then a 18" soffit = 9', floor is carpet, wall with screen covered with black fabric. Can anyone help me sort this out? I definitely need bass traps.



Try this * dedicated Auralex forum *.


I use Aurlaex in my cinema and it's the best upgrade I've ever done.


----------



## Ethan Winer

Norm,


> should I place panels behind the screen, behind the speakers? Where would you put them on the side walls ... Can anyone help me sort this out? I definitely need bass traps.


----------



## myfipie




> Quote:
> Originally Posted by *RicosRevenge* /forum/post/0
> 
> 
> myfipie... I raced offshore powerboats on the APBA Pro-Series circuit. I have a 34' Eliminator V-bottom with twin 500 HP Mercs in Factory 2 class, she ran 96.5 MPH on radar. I love going fast on the water (Top speed 165 MPH in a 46' Skater cat with twin 1400 hp Sterlings).
> 
> 
> Thanks for not lighting me up on my lay-person's description. I find that there are many times when the incredible knowledge on this forum can overpower the novice. If I was given a more direct approach, it would have taken me MUCH less time to track down the stuff I needed. BobGold's co-efficient charts are key!



Well 6 knotts is really fast to me!!! ha h aha


I got to tell you that sometimes we get so lost in the science that people get plan turned off to acoustics, throw up there hands and say for get it, in fear of doing it wrong.. Really the only thing you can do wrong is do nothing at all.









We all owe a lot to Bob!!


Glenn


----------



## WoodMonkey

I have a question for you HT gurus. Forgive my newbie-ness.









Why do so many folks use GoM fabric on their walls? I can understand its use when its hiding speakers, but what purpose does it serve on the wall? An accoustically transparent material seems like it would do nothing for sound. Hopefully someone can set me straight. Thanks.



Marc


----------



## ChrisWiggles

because usually there is absorbing material behind it, or diffusors or other acoustical devices and speakers and whatnot. It's mainly for aesthetics, and to be transparent to any of the aforementioned devices that would be behind it.


----------



## bpape

Exactly. The idea is not no have to worry about the look of what's behind. Whether it's a full covered wall of batting/duct liner or scattered treatments so you don't have to worry about aesthetics of patterns and spacing - the cloth does the trick.


----------



## jacampbell

In the same vein, I need advice on two things;


1. What other fabrics besides GOM can I use? Names would be nice.


2. I can't find OC 703 anywhere. Mind you I have only checked HD and Rona?

Where should I look?


Thanks

John


----------



## myfipie

My understanding is that OC is going to get harder and harder to find... If you want to build yourself you may want to contact Bryan about getting some.. BTW Bryan I got the notice that OC is going up 9%..


Glenn


----------



## oakbluff

John- I see you're in Canada as well (I'm in winnipeg). I phoned a few places too- and actually had luck with a local building supply store this week. They had no issues ordering in 703. The only catch was that I had to buy a minimum of 12 2x4 sheets of it. Kind of pricey though- they wanted cdn$18 per sheet. So my advice is to phone local places. If they carry OC product, they should be able to get it in.


----------



## ChrisWiggles

fiberglass board like OC 703/705 is more industrial/commercial insulation you usually wont find it at HD or similar. Look in the yellow pages for insulation supply places, hvac supply etc and call and ask for rigid fiberglass board such as OC 703, they'll know what you're talking about shouldn't take you long. If you're on the boonies obviously you'll probably need to find places near civilization, but shouldn't be hard to find, there are other brands than OC its all the same stuff and bout the same price so they'll know what you mean. BTW it's usually used for big HVAC ducting and such, but any competent commercial supply guy will know exactly what you're talking about.


----------



## diegolifer

Can anyone direct me to someone in San Diego who sells any of the accepted 1" absorption materials listed on this thread? I'm coming up with absolutely nothing so far. Thanks.


----------



## Tweakophyte

Hi-


I finally got through this thread and am well on my way to reading Ethan's FAQ. It is still not clear to me what might happen to bi-polar speakers if you treat the front wall. I am okay the thought of removing the first reflection from the speakers I have, but I'd like to hear from people that have heard them. Has anyone done this?


----------



## HuskerHarley




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> I finally got through this thread and am well on my way to reading Ethan's FAQ.



Congratulations...










HH


----------



## Tweakophyte




> Quote:
> Originally Posted by *HuskerHarley* /forum/post/0
> 
> 
> Congratulations...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> HH



At least I have pics of MY HT online...


----------



## Tweakophyte

I have a few more...


- What does putting in a broadband bass absorber do for total output? I understand it will tame my peaks (and reduce smearing). Will my max SPL drop a few db? Will it just flatten the response but allow the SPL to flow? (Let's assume I EQ'd my peaks out with regards to max SPL... make sense?)


- It's pretty easy to understand how absorbtion will reduce a peak. How does it effect a null? For converstation, assume both a dip and a deep drop.


- What are some good ways to treat a null with bass traps? Would you only trap a portion of the room (i.e. one wall with the room dimension causing the null)?


- I am considering broadband bass traps in certain corners of my room. Only one corner allows for floor to ceiling (soffit) treatment using the 2' hypotenuse 703 method I have read about. How effective would it be do only do from the floor to half way up? I might go from 2' to 1' to smaller (so I can make it all the way up). Any comments on that?


- My current surrounds are bi-polar and would be located close to any corner bass trap I might construct. Is it advisable to use a semi-reflective surface on a portion of the trap so I can keep the surround non-locatable?


PS... pics of my HT in the link in my sig...


Thanks!


----------



## LarryChanin




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> I have a few more...
> 
> 
> - What does putting in a broadband bass absorber do for total output? I understand it will tame my peaks (and reduce smearing). Will my max SPL drop a few db?



Hi,


Over at Siegfried Linkwitz's web site there's a discussion of how to calculate Amplifier power needed to sustain a Reference Level if you know the type of speaker, the volume of your room, the Reverberation Time of your room, the efficiency of your speakers and the reference level desired.


As mentioned above the amount of amplifier power needed to sustain a particular sound pressure level depends on a number of factors, including the overall Reverberation Time of the room. So depending on how much the broadband bass absorber decreases Reverberation Time there could be a measurable effect on power requirements, and therefore maximum SPL level.


For example, when I used Mr. Linkwitz's method to calculate the per channel requirements of my home theater it came out to about 152 watts to sustain a 100 dB sound pressure level from one of my main speakers based on my room's Reverberation Time of 230 ms. If my room had a Reverberation Time at twice that duration (460 ms) the required power would only be about 76 watts to maintain a 100 dB sound pressure level.


However, while my power requirements might be reduced if I removed half of my absorption, the increase in Reverberation Time would adversely impact the sound quality for multi-channel listening, which depending on whose formula you use, should ideally be roughly 230 ms for my room size.


Larry


----------



## dallas27

After reading this thread, it is obvious to me that no matter what I would do to treat a room, it would be wrong.


Is there not a good book or two out there with full intructions or specifications on how to build a quality (not nerd-prefect) HT of varying sizes? Maybe THX Specs or the like.


Honestly, the amount of varying opinions and minute details in this thread seems very piecemeal to me.


----------



## dallas27




> Quote:
> Originally Posted by *LarryChanin* /forum/post/0
> 
> 
> Hi,
> 
> 
> 
> 
> As mentioned above the amount of amplifier power needed to sustain a particular sound pressure level depends on a number of factors, including the overall Reverberation Time of the room. So depending on how much the broadband bass absorber decreases Reverberation Time there could be a measurable effect on power requirements, and therefore maximum SPL level.
> 
> 
> For example, when I used Mr. Linkwitz's method to calculate the per channel requirements of my home theater it came out to about 152 watts to sustain a 100 dB sound pressure level from one of my main speakers based on my room's Reverberation Time of 230 ms.
> 
> 
> Larry



Wouldn't it just have been a hell of a lot easier to use a dB meter and turn it up until you reached 100dB's? Save your pencil lead maybe?


----------



## Tweakophyte

Larry-


EDIT

[strikethrough]

Thanks for the link... I am too tired for math in the morning, but it looks like a reduction in ring time equates to a reduction in power requirement. Did I miss a section on the SPL being absorbed by traps?


Now I wonder if the reduction in ring time offsets the absorbed sound? ...check my math (if you like)... like I said, I am generally too tired to think in the morning.







[/strikethrough]


...no more math before coffee


----------



## Terry Montlick




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Larry-
> 
> 
> Thanks for the link... I am too tired for math in the morning, but it looks like a reduction in ring time equates to a reduction in power requirement.



No. 'Fraid its the other way around. A reduction in reverberation time results in an increase in power requirement. That's because increased reverberation provides more sound energy storage in the room. An amplifier doesn't need to put out as much power to excite the room to a particular sound level. The downside, however, is a reduction in clarity of transient sound.


Regards,

Terry


----------



## Ethan Winer

Tweaks,


> Did I miss a section on the SPL being absorbed by traps?


----------



## Tweakophyte




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> No. 'Fraid its the other way around. A reduction in reverberation time results in an increase in power requirement. That's because increased reverberation provides more sound energy storage in the room. An amplifier doesn't need to put out as much power to excite the room to a particular sound level. The downside, however, is a reduction in clarity of transient sound.
> 
> 
> Regards,
> 
> Terry



No more math before coffee!










That was more intutive anyway.


----------



## Tweakophyte




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Tweaks,
> 
> 
> > Did I miss a section on the SPL being absorbed by traps?


----------



## Ethan Winer

Tweak,


> My concern is I am going to improve my room so much that I'll need (... REALLY need) another sub.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Tweaks,
> 
> 
> > Did I miss a section on the SPL being absorbed by traps?


----------



## BasementBob

Tweakophyte:



> Quote:
> What does putting in a broadband bass absorber do for total output? I understand it will tame my peaks (and reduce smearing). Will my max SPL drop a few db? Will it just flatten the response but allow the SPL to flow? (Let's assume I EQ'd my peaks out with regards to max SPL... make sense?)



Absorbtion reduces the height of modal peaks, and reduces the depth of modal nulls.


Absorbtion also reduces the sound pressure level of a steady noise, according to the formula:

reduction in SPL = 10 log (a2 / a1)

where a1 is the absorbtion in sabins of the before room, and

a2 is the absorbtion in sabins of the room after additional treatment.


As you add absorbtion you will turn your volume knob up to achieve the same SPL.

You can keep adding absorbtion until your speakers start distorting, or melt and fail completely.



> Quote:
> - What are some good ways to treat a null with bass traps? Would you only trap a portion of the room (i.e. one wall with the room dimension causing the null)?



Have one.


Absorbers damp a mode. They treat both peaks and nulls of that mode.




> Quote:
> - I am considering broadband bass traps in certain corners of my room. Only one corner allows for floor to ceiling (soffit) treatment using the 2' hypotenuse 703 method I have read about. How effective would it be do only do from the floor to half way up?



It would be a little more than half as many sabins.


----------



## LarryChanin




> Quote:
> Originally Posted by *dallas27* /forum/post/0
> 
> 
> Wouldn't it just have been a hell of a lot easier to use a dB meter and turn it up until you reached 100dB's? Save your pencil lead maybe?



Hi Dallas,


Either I'm missing the humor in your posting, or you are missing the point. Since I didn't see any of those cute smilely faces





















etc., in your posting indicating your response was tongue-in-cheek, I'll assume that you're serious.


Tweakophyte asked whether adding a broadband bass trap would effect his maximum SPL, not how far should he twirl his dial to reach a given SPL dB. My calculation was intended to demonstrate that there could be a significant difference in power required to reach a given SPL if the total absorption of a room were to change significantly.


I appreciate your concern, but with today's computers not a lot of expensive pencil lead was harmed in the making of these calculations.










Seriously, I had recently gone through the exercise to calculate the how much amplifier power I would need to sustain reference levels in my home theater when playing some of the more energetic action movies. It was virtually no additional effort to substitute another value for Reverberation Time. On the other hand, ripping out half of my insulation to empirically demonstrate the differences, now that would have been an effort.










Larry


----------



## Tweakophyte

Bpape gave me this info from another area:


> Quote:
> If you're looking at answers about the bipolar surrounds then the answer is that yes - it will absorb some of the mids and highs depending on if they're angled or not will determine how much to a certain extent.
> 
> 
> To negate this (on the rear wall anyway and for surrounds), the bass absorbers in the corners could (maybe should depending on the room analysis and what it needs in terms of HT absorbtion - don't want to overdo the highs) be covered with a scrim of some sort. I have the FRK (just the facing) that you can attach via spray adhesive - or you can use kraft paper. This will reflect the highs and make the mid frequency absorbtion less efficient. Think of an absorbtion 'curve' that starts out at about 1.2 or so at 125Hz and gradually goes down after 250Hz to around .3 at 4kHz.
> 
> 
> On the front wall, that's a bit trickier. Bipolar speakers in front present some challenges and issues. If it's just a rear tweeter, I'd scrim face just behind the tweeter - maybe 1 sq ft and leave the rest of the front wall soft to deal with surround reflections from the front. Whether or not you can scrim face the bass corner absorbers depends on how close your speakers are to the corners. Normally, I'd say leave the middle soft and scrim the top and bottoms. But, with the rear tweeter, you might not be able to do that - might have to scrim the whole thing - or just the middle foot or 2 for the rear tweeter.
> 
> 
> Some people just treat bipoles in a room like a normal speaker and absorb the rear wave. While this gets rid of the anomolies generated by a bipolar design, it also can tend to skew the frequency response as those were voiced with that tweeter in the equation.
> 
> 
> The cotton is a great product. It's class A fire retardant, non-shedding, non-itching, totally natural, etc. No gloves or long sleeves required to work with it. Cutting it is a bit of a trick but if you take your time and use a VERY sharp razor knife at a shallow angle and with multiple light strokes it's not too bad. This is for the thicker stuff. For the thinner 3lb and 6lb material, you can acutally use a good sharp pair of scissors (big ones) or can also use the knife as described above. I have people who cut it into triangles to stack up solid all the time.


----------



## Tweakophyte

Some material cost/handling questions... With kids, I am concerned with contamination.


How many of you have worked with Cotton absorbers compared to the semi-rigid fiberglass (703)? How does the performance compare for say, a Mondo Trap? How is the cost?


Also, I have access to some excess (maybe 30-40ft) of Linacoustic. How is that to work with compared to the 703?


I am thinking about making some front-wall absorbers behind the mains, some mondo and semi-mondo (2' and 1' sides) traps in the back corners (and maybe front), and some treatment above the screen-wall. (see the pics in my gallery or my sig.)


Any comments?


----------



## Tweakophyte

PS Ethan, Terry... I bumped your eq vs treatments thread...

nudge, nudge


...and thanks to all of you for you comments...


----------



## Thedarksyde

Answers! And Questions?!?!


Hello people of the acoustic treament thread, I would like to give you some info on my experiecnes. I decided that using 703 wasnt gonna work for me becuase I didnt want to wrap all that stuff in fabric. So I went in the search for Black Acoustic Sound Board. I have found it. Available by Knauf, at a place is round rock TX called, General Insulation (they have a website). I found this loaction out by contacting Knauf directly from thier site, and I got an email back in a very short time.


I called this place, and they do not have it in thier Round Rock store, only in Dallas, but can get it to me, it sells in 4'X10'X1" sheets. It is 1 dollar per square foot, and only sells in 100 square foot sets. So I have to buy 200 or 300 square feet. That is the info, now here is the questions...


I wanted to use it on my front wall completly and my celing. The celing to make the celing black, and the front wall for front wall absorption, along with bass traps, I figured that I would do all of celing and wall, and corners, and that was 288 square feet. I was not sure how much this stuff was when I mad this decision. It will cost me $356.40 total for delivery and tax. I am not sure if I wanted to spend this much (was thinking $200). So I was thinking about cutting back to 200 square feet, which will allow the whole celing (to make it black) and some of the front wall and bass traps. The area is 16X12X8 rectangle, with the screen on the 12 foot wide wall. What would you do? Thanks for the replies.


----------



## HuskerHarley




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Bpape gave me this info from another area:





> Quote:
> The cotton is a great product. It's class A fire retardant, non-shedding, non-itching, totally natural, etc. No gloves or long sleeves required to work with it. Cutting it is a bit of a trick but if you take your time and use a VERY sharp razor knife at a shallow angle and with multiple light strokes it's not too bad. This is for the thicker stuff. For the thinner 3lb and 6lb material, you can actually use a good sharp pair of scissors (big ones) or can also use the knife as described above. I have people who cut it into triangles to stack up solid all the time.



I did exactly what Bpape suggested (Thank-U Bpape) "cut it into triangles to stack up solid" I did this in all four corners (BAC stacked floor to ceiling covered with GOM)


I don't have fancy gear to test everything for showing graphs, just the Excel & Rat Shack type of things...


But my ears tell me that my room is a lot better with BAC in corners and 103 panels on the walls and it looks OK to the WAF part.


HH


----------



## Ethan Winer

Terry,


> let's go to the videotape, and see if this matches our recent experiment!


----------



## rudedoggy

I am a bit confused....I read on manufacturer sites that sound absorbing cloth and other insulation types can be installed behind the drywall between the studs....I am assuming that you would only do that in the case that you want to stop noise from passing through....A set-up like that would not actually help within the room at all right? I mean the drywall would be reflecting the sounds back and forth correct? I am may be way off, but from what I've read I was under the impression that the absorbing material must be directly exposed to the sound....


In any case, I am about at budget's end but I need to do some accoustic treatments for the walls/ceiling (absorbtion). I do not want to use fiberglass because I worry about my childrens exposure to material that will be "exposed" behind GOM. Can someone give me a reasonably priced alternative that is not in any way toxic? Also, *please post where they may be ordered from*... Reminder: I am seriously low on funds after renovating the entire basement and all the new equipment, so I am looking for effective but inexpensive treatments (I don't mind if it requires a lot of labor.)


Thanks,

Rudedoggy


----------



## Tweakophyte




> Quote:
> Originally Posted by *HuskerHarley* /forum/post/0
> 
> 
> I did exactly what Bpape suggested (Thank-U Bpape) "cut it into triangles to stack up solid" I did this in all four corners (BAC stacked floor to ceiling covered with GOM)
> 
> 
> I don't have fancy gear to test everything for showing graphs, just the Excel & Rat Shack type of things...
> 
> 
> But my ears tell me that my room is a lot better with BAC in corners and 103 panels on the walls and it looks OK to the WAF part.
> 
> 
> HH



Did you worry about the color of the BAC? Did you make any panels with this for you front wall? It looke like the cotton has a little more acoustic absorbtion than the 703 down low, and is pretty close to the Linacoustic I grabbed from bob's site.


Product thickness mounting density 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC

703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00

Echo Eliminator (Cotton) 2" 3pcf A 0.35 0.94 1.32 1.22 1.06 1.03 1.15

Permacote® Linacoustic® R-300 2" (51mm) 3.0 pcf (48 kg/m3) 0.26 0.73 1.10 1.10 1.04 1.03 1.00


Harley, did you check out the price of other options? Why cotton?


Does anyone have pics of this stuff?


Thanks,


----------



## swithey




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Harley, did you check out the price of other options? Why cotton?
> 
> 
> Does anyone have pics of this stuff?
> 
> 
> Thanks,



bpape (Bryan) has a few pics of the cotton on his website. Here are a few -- left is the 2", right is 4" material:


















Steve


----------



## HuskerHarley




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Did you worry about the color of the BAC? Did you make any panels with this for you front wall?
> 
> 
> Harley, did you check out the price of other options? Why cotton?



No worry GOM covered it up.


Corner panels are BAC covered with GOM.


Yes on price options....BAC at the time seemed the way to go and it was so easy.


I took a few Pics of the room but I don't know how to get them to display?


PM me with your email and I'll send them to you if you want to see what a amateur can do to mess up good intentions


HH


----------



## rudedoggy

Here is a thought...What do you anticipate the problems would be if I did NOT drywall the inside of the theatre room, and instead. filled the space between the studs with accoustic cloth insulation, walled it with duct liner, and used gom attached to 1 X 2" firring strips which I will attach to the door stud. Then stretch the fabric to the inside of a stud roughly 50 inches horizontally and the take a second piece of gommed firring strip and attach it likewise to the same stud and continue on down the wall.... (I probably didn't explain it right) It should appear boxed that way (I can use molding over top and bottom) but there would be no drywall used (two side are concrete with 2 X 4 's used as furring strips to give a little width for the duct liner - duct liner only on the concrete sides - maybe double sheeted). I could then 2 layer the drywall on the outside of the theatre walls for sound deadening... Would this be a dysfunctional setup? I am concerned about how the wall sound would play out and if there are any drawbacks for not using the drywall on the interior of the walls... Any comments/concerns would be appreciated...


It would seem to me that the 4" of cloth between the studs and the duct liner covering it would be a pretty absorbent combo, but then again I know very little about anything audio...



Thanks,

Rudedoggy


----------



## ebr

I'm no expert, but I'm guessing much too absorbent.


Also, I'm not sure that construction would pass code.


----------



## rudedoggy

Is drywall required under code in a basement? The accoustic cotton I am talking about is actually used to replace R13 and R19 fiberglass and in and of itself would meet code...I don't know about the replacing of drywall will duct liner as a violation of code. Both have some fire resistance ( I am pretty sure that was listed under the liner..)...maybe someone can answer that? Also, how much is too absorbent? Anyone else have any suggestions on my earlier post?


Thanks,

Rudedoggy


----------



## Hughman

Looks like I'll be constructing some floor to ceiling corner bass absorbers the next couple weeks and have a few questions.


I can not source Owens corning 703 or 705 locally so will be using Ottawa Fibre OFI-48 3lb 2x4 foot 2" thick material doubled up, maybe tripled, the acoustic properties of the FRP faced material look excellent


First question.....when doubling up faced material should only the first outside layer be faced or is there any bass advantage to using faced material for both layers? I'm not too concerned about mid to high frequency absorption at this point.


Secondly, should doubled layers be glued together or would a slight space between them absorb bass better.


Third, I was planning on making enough absorbers for four corners of the primary HT area but due to the room(s) configuration might it be better if one or two were situated elsewhere. I don't have any analyzing programs at this point except for the usual meter and test cd's so am looking for general/probable positioning advice for the room(s).


Attached is the room layout which is a basement, doubled up 1/2 inch drywall over 3" styrofoam board over concretre /fiberglass insulated 5/8 drywall ceiling. Flooring is (soon to be again) carpet over pad. The viewing area is about 19' long and 12' wide at the front and back, obviously wider in central area. Entire speaker/screen area and back wall lined with black velvet.


I'm am not using subwoofers and my general bass response shows a belled hump from 80 to 200 hz will lulls on either side and an 10db gain between 25 and 30hz. While the FR doesn't really look that bad the bass definitely is a little indistinct and needs improvement.


Thank-you


----------



## bpape

When using faced product, you should remove the facing from everything except the face that is toward the room. The other pieces should be unfaced.


You don't need to glue multiple layers together. If you want to add air space, that can only help by getting the front one further into the room.


Looking at your sketch, I'd do the front corners and the wall/ceiling corners in the front and rear of the theater area. It's such an odd shaped room that you'll still need some more but that will be a start.


Some of your FR issues are likely due to SBIR from the mains being close to boundaries andnot absorbed. You might also want some bass absorbtion beside the speakers to help smooth things out. If you got a sub, you could tune the bass response without having to move the mains.


Also, the seating appears IIRC to be pretty close to the back wall. I'd move it out - that will help smooth things also.


----------



## Hughman




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> When using faced product, you should remove the facing from everything except the face that is toward the room. The other pieces should be unfaced.
> 
> 
> You don't need to glue multiple layers together. If you want to add air space, that can only help by getting the front one further into the room.




Ok great, this will reduce the cost and simplify the construction.




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Some of your FR issues are likely due to SBIR from the mains being close to boundaries andnot absorbed. You might also want some bass absorbtion beside the speakers to help smooth things out. If you got a sub, you could tune the bass response without having to move the mains.



My room is still packed away due to a water leak but IIRC the speakers average about 10" from the side walls and the rear of the 18" deep speakers are about 35" from the rear wall. I just downloaded Ethan Winers Boundary Frequency/Distance calculator and this would indicate the side wall distance shouldn't really come into play at the frequencies I'm having problems with but the rear wall distance very well could be contributing to the problem. Regardles, my side walls are covered with velvet attached to a frame which I can easily fit some absorption panels behind to experiment.



> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Also, the seating appears IIRC to be pretty close to the back wall. I'd move it out - that will help smooth things also.



The seating puts the listeners head in the 40-44" range from the rear wall. Moving out definitely helps the bass response but then puts me too close to the video screen plus it encroaches on the path to the door beside the bar. I can only hope the traps will help somewhat.


Thank-you for spending time answering my questions.


----------



## Terry Montlick

Great answers as usual, Bryan!


Regards,

Terry


----------



## rudedoggy

Still want to get some expert accoustical advice on the following:


Here is a thought...What do you anticipate the problems would be if I did NOT drywall the inside of the theatre room, and instead. filled the space between the studs with accoustic cloth insulation, walled it with duct liner, and used gom attached to 1 X 2" firring strips which I will attach to the door stud. Then stretch the fabric to the inside of a stud roughly 50 inches horizontally and the take a second piece of gommed firring strip and attach it likewise to the same stud and continue on down the wall.... (I probably didn't explain it right) It should appear boxed that way (I can use molding over top and bottom) but there would be no drywall used (two side are concrete with 2 X 4 's used as furring strips to give a little width for the duct liner - duct liner only on the concrete sides - maybe double sheeted). I could then 2 layer the drywall on the outside of the theatre walls for sound deadening...


Would this be a dysfunctional setup?


I am concerned about how the wall sound would play out and if there are any drawbacks for not using the drywall on the interior of the walls... Any comments/concerns would be appreciated...


It would seem to me that the 4" of cloth between the studs and the duct liner covering it would be a pretty absorbent combo, but then again I know very little about anything audio...



Thanks,

Rudedoggy


----------



## Terry Montlick




> Quote:
> Originally Posted by *rudedoggy* /forum/post/0
> 
> 
> Still want to get some expert accoustical advice on the following:
> 
> 
> Here is a thought...What do you anticipate the problems would be if I did NOT drywall the inside of the theatre room, and instead. filled the space between the studs with accoustic cloth insulation, walled it with duct liner, and used gom attached to 1 X 2" firring strips which I will attach to the door stud. Then stretch the fabric to the inside of a stud roughly 50 inches horizontally and the take a second piece of gommed firring strip and attach it likewise to the same stud and continue on down the wall.... (I probably didn't explain it right) It should appear boxed that way (I can use molding over top and bottom) but there would be no drywall used (two side are concrete with 2 X 4 's used as furring strips to give a little width for the duct liner - duct liner only on the concrete sides - maybe double sheeted). I could then 2 layer the drywall on the outside of the theatre walls for sound deadening...
> 
> 
> Would this be a dysfunctional setup?
> 
> 
> I am concerned about how the wall sound would play out and if there are any drawbacks for not using the drywall on the interior of the walls... Any comments/concerns would be appreciated...



Hi Rudedoggy,


It would be dysfunctional for sound isolation. Sound would travel easily to adjacent rooms, and vice-versa. I don't know about your local building code requirements, but this could be a show-stopper.


For sound quality otherwise, it *might* be good. I say might because one would have to calculate the absorption of what you propose, and see if it is well balanced for all frequencies. You might have to use some drywall or better, diffusive treatment to reduce absorption. You might also have to use different thicknesses and densities of absorber than just duct liner.


Regards,

Terry


----------



## jandawil

Anyone ever hear of a product called sound board by Weyerhauser. I saw some at Home Depot when I was looking for a solution for some accoustic paneling. It is a very fibrous soft wood product 1/2" thick and they are 4'X8' sheets and they are only $8 each. I was going to double them up for 1" and than wrap with a nice cloth and than hang on walls about 1' off the walls. They also had some JM 2" thick foam stuff also in 4'X8' sheets for about $20 each. I was also thinking I could manufacture some bass traps out of those by cutting into 12" squares and stacking them or 12" strips and attaching them all together to make a sort of 12" sq pillar 8' high. Would this work as a bass trap as well.


----------



## Terry Montlick




> Quote:
> Originally Posted by *jandawil* /forum/post/0
> 
> 
> Anyone ever hear of a product called sound board by Weyerhauser. I saw some at Home Depot when I was looking for a solution for some accoustic paneling. It is a very fibrous soft wood product 1/2" thick and they are 4'X8' sheets and they are only $8 each. I was going to double them up for 1" and than wrap with a nice cloth and than hang on walls about 1' off the walls. They also had some JM 2" thick foam stuff also in 4'X8' sheets for about $20 each. I was also thinking I could manufacture some bass traps out of those by cutting into 12" squares and stacking them or 12" strips and attaching them all together to make a sort of 12" sq pillar 8' high. Would this work as a bass trap as well.



Forget about them both.










What you need is fibrous, open material with moderate air flow resistance (fiberglass, mineral fiber, cotton, polyester). Neither of these materials will work.


Regards,

Terry


----------



## Westshorestudios

I'm not sure if this question goes in this forum or in the construction forum . . .


My speakers are built into my screen wall, to be flush with the screen. They sit about 4 inches above the stage area. The stage area is poured concrete and extends about 24-30 inches in front of the speakers. My concern is about early reflections from the stage. My questions are:


(1) should this be a concern?


(2) if it should be a concern, what should I cover the stage with? Carpet? GOM over linacoustic / sound board? Other? Rarely will anyone stand on the stage, but I'm sure it will happen from time to time.


Thanks


----------



## bpape

I'd cover in carpet generally. Whether it's a reflection point or not depends on where your seats are.


----------



## Thedarksyde

I am sorry if this has been answered before, There is soo much in here now it is hard to read it all, im trying.


I just called SPI, and they said they carry 703! (Victory) in single sheets of "non-faced" that I can buy at 1.30 a sqare foot. Or Faced in bundles of 192 square feet at .73 a sqare foot. Could someone please exaplain the difference between faced and non-faced? And what should I do if I get the non-faced?


----------



## rudedoggy

Terry,


I have a 19.5 X 11.5 ft room 7.5 tall. Two basement walls. 6.1 sound system. I am thinking about taking the carpet up the first 3 or so feet of the wall and doing a chair rail and some framed "boxes" with GOM covering holding cotton duct liner (.60NRC I believe) along all back and side walls. Will this be sufficient you think? I have no understanding of the underlying science of all this - which I might add you all have me in awe of.


Thanks,

Rudedoggy


----------



## Borky

I need to sound proof my dorm room a little so that I don't get complaints from the people living upstairs and downstairs anymore. They've mostly been about the bass coming through. What are some cheap solutions I can get for this? I was thinking placing a dynmat mat under the sub and acoustic panels like these http://www.envisiononline.net/acousticpanel.html on the ceiling. Would this do the job or do I need some sort of sound proofing material?


I already have carpet on the floor, but the sub isn't on carpet. The floor is made of cermaic tiles and the ceiling looks like some stone or something.


I really don't know about this stuff and I don't need anything fancy.


----------



## bpape

DarkSyde - 1.30 for 1" 703 unfaced is pretty steep but they'll sell it to you a piece at a time. Conversely, 1" FACED 703 for .73 sq foot is pretty reasonable. If you can use all of the material, you can easily peel the facing off.


For reflection points you want unfaced. The faced has a kraft paper and foil scrim on one side. This can be very useful when place on top of thicker material for bass absorbtion without overdeadening the highs.


Doggy, that will be VERY overly dead IMO. I wouldn't do the carpet up the wall thing.



Sorry Borky. Hate to break it to you but you're not going to soundproof a dorm room no matter what. Even if you could, cheap and soundproofing don't go together. It's all in how the structure is built which you can't control. Nothing you do inside the room (other than may be a LITTLE but by putting the sub on something like an Auralex SubDude) is going to do much of anything in the way of soundproofing - sorry.


Oh, and thanks Terry.


----------



## Borky

What would putting a few acoustic panels like maybe this kit http://www.sweetwater.com/store/detail/RoomDST36B/ do? Wouldn't they "absorb" some of the sound?


----------



## myfipie

Bork,


That is a kit that is used to control the acoustics in the room.. It has nothing to do with soundproofing at all.. Soundproofing is totally differant thing, as Bryan is trying to point out to you..


Glenn


----------



## rudedoggy




> Quote:
> Originally Posted by *rudedoggy* /forum/post/0
> 
> 
> Terry,
> 
> 
> I have a 19.5 X 11.5 ft room 7.5 tall. Two basement walls. 6.1 sound system. I am thinking about taking the carpet up the first 3 or so feet of the wall and doing a chair rail and some framed "boxes" with GOM covering holding cotton duct liner (.60NRC I believe) along all back and side walls. Will this be sufficient you think? I have no understanding of the underlying science of all this - which I might add you all have me in awe of.
> 
> 
> Thanks,
> 
> Rudedoggy



Is it really bad to do partial carpeting on the walls? I could have sworn I read someone saying to do it....Also, this is going to be used almost entirely for movies/home theatre, so shouldn't I want it to be "dead" as possible? It is all very confusing. Please help a newbie out with some advice guys...


Does anyone know if carpet padding has any absorbtion (NRC). I don't know what to look for for absorbant materials but it would seem to be a low cost alternative if ti does have any NRC value... Is there any common materials you can think of that have a respectable NRC other than fiberglass? Certain cloth types, batting you get form a fabric store etc etc etc


thanks,

Rudedoggy


----------



## Thedarksyde

bpape, yea, I know 1.30 is kinda high, but I figured that is the price I pay for not buying a whole bundle. I think 2 sheets to play with is worth the price hike.


Simpler question for the non-faced vs faced. What should I do for corner bass traps? Faced or non- and if faced, facing which way?


This is what I am gonna start with and go from there, see how I like it and then think about buying a bundle or 2. Thanks.


----------



## darkhorror

Well I am getting ready to put my acoustic pannels together, I have mineral wool, speaker grill cloth, trying to figure out what I want to attach the stuff too. Maybe some lighter wood, foam board, who knows. I hope to put them together tomorrow. I hope everything works as planned.


----------



## Ethan Winer

Dog,


> Is it really bad to do partial carpeting on the walls? I could have sworn I read someone saying to do it


----------



## rudedoggy

Ok thanks, carpet should be out...Now, lets say instead I do ceiling to midway to floor with boxes (covered with GOM) with batting in them and use some silence FR fabric at the bottom instead of carpet.... Would that be a better solution?


Also, I was still wondering if anyone know if carpet padding has any absorbtion (NRC). I don't know what to look for for absorbant materials but it would seem to be a low cost alternative if ti does have any NRC value... Is there any common materials you can think of that have a respectable NRC other than fiberglass? Certain cloth types, batting you get form a fabric store etc etc etc.



thanks,

Rudedoggy


P.S. If anyone is interested in splitting a bolt of black silence fabric contact me. It is like $3 less per yard that way.... I plan on ordering some in the next week or so.


----------



## Borky

I guess I'll put a subdude under the sub and see what that does. I was considering a dynmat too, has anyone ever tried one of those with a subwoofer?


----------



## myfipie




> Quote:
> Originally Posted by *Thedarksyde* /forum/post/0
> 
> 
> bpape, yea, I know 1.30 is kinda high, but I figured that is the price I pay for not buying a whole bundle. I think 2 sheets to play with is worth the price hike.
> 
> 
> Simpler question for the non-faced vs faced. What should I do for corner bass traps? Faced or non- and if faced, facing which way?
> 
> 
> This is what I am gonna start with and go from there, see how I like it and then think about buying a bundle or 2. Thanks.



You would want to keep the facing to the front of the panel, NOT THE BACK.









Keep it on if you want to not absorb high end, but also keeping the facing on will act as a membrain which will absorb more low end.. For only having 2 I would go with them faced and see if that helps..


Glenn


----------



## bpape

Doggy,

If you want some acoustical value, use acoustical materials - sorry. Don't mess with carpet pad, boxes, etc. Get some rigid fiberglass, acoustical cotton, or mineral wool that is specifically tested for use as acoustical materials. You'll spend more time and hassle trying to save a few cents, not really save much, and end up with something that doesn't work NEARLY as well.



Dark,

If you're going to make a judgement as to what it can do for you in the bottom end, you're going to need more than 2 pcs - especially as it's only 1" material if my calcs are correct. To do much of anything in the bass, you'll want 4". A box isn't a bad investment.


----------



## WoodMonkey

Hey guys. Do any of you use those accoustic foam panels (the wedge type) as sound absorbers in your rooms? Compared to the prices of standard accoustic panels, these things are a steal! Is there a drawback to using this material?


Some of these room kits are really reasonable.


marc


----------



## myfipie

If you are going to use foam then you want to use 3" or more and from Auralex.. Companies like Foam by mail sell junk.. But even with 3" foam from Auralex you are going to still have to put bass trapping to absorb low end. Foam will not absorb that and if you just put foam in without bass traps then your high end will be tamed but the low end will be bouncing all around in your room. Making the bass unclear and muddy... Low end is the area you really want to focus on first...


Glenn


----------



## rudedoggy

bpape,


I already went the route of trying to locate rigid fiber and linacoustic in my area and it was a no-go. It seems that for the most part hardware/building supplies wish to deal only with contractors or in larger orders. I spent weeks trying to find the formaldehyde free rigid fiberglass with no success. Besides that, markup on anything listed as 'acoustic' seems to be fairly ridiculous for the most part. No blame for that, its just high in demand - especially any type of installation right now... Add shipping on to it and your talking some serious money for the most part...As for the acoustic cotton, it seems like a reasonable alternative, but of all the companies supposed to carry it, only yours has even replied to my requests for a quote.


Thats why I was wondering if anyone has tested the NRC of some of the more readily available/household type items that you can pick up at say Walmart/Lowes (like the carpet padding I mentioned)?


I realize this will probably yield second rate alternatives and not necessarily a 'made for acoustic' material - which may not be an option for the audio purists in the house, but would be a convenient for those of us on a tight budget with little time to scour the nation for JM black acoustic board sources...


I have even been considering wrapping some of the contractor ceiling tiles listed as acoustic ($23 for box of 10 - 24" X 48"X 5/8" - .55 NRC tiles at Lowes) in GOM...


Before I take that route though, I wanted to challenge the more curious/industrious experts here to provide some other pedestrian and readily found options that might be comparable to some of the professional stuff. I would bet some of you audio geeks ( I say that with affection) have already tested the NRC's of stuff like Walmart pillow stuffing and stuff for NRC values - so now is the time to sing out.


Thanks,

Doggy


----------



## myfipie

>I have even been considering wrapping some of the contractor ceiling tiles listed as acoustic ($23 for box of 10 - 24" X 48"X 5/8" - .55 NRC tiles at Lowes) in GOM...


----------



## BasementBob

rudedoggy:


Where are you in the world?

Did you try internet dealers?


Home Depot around here sells acoustic ceiling tiles that are made out of yellow fiberglass. Just take the plastic wrapper off the box and leave them 4" thick. I don't know how expensive that is. In Ontario Canada, Roxul Safe N Sound is also available at home depot.


There's a variety of things that can be done with fluffy fiberglass pink. Including compressing your own absorber out of it, or just using it as fill for deep (2' +) bass traps.


Walmart pillow stuffing is Polyester Batting. Probably OK. Don't know about the cost / ft^3 though.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *WoodMonkey* /forum/post/0
> 
> 
> Hey guys. Do any of you use those accoustic foam panels (the wedge type) as sound absorbers in your rooms? Compared to the prices of standard accoustic panels, these things are a steal! Is there a drawback to using this material?



I assume you mean aside from their ugliness. My wife would not tolerate any of these in any color.


Kal


----------



## rudedoggy

Actually guys, I was hoping someone could point out some more novel materials rather than the fiberglass route.


The challenge is to find common materials (ie packing styrofoam, pillow stuffing, ball of tape - I don't know...) and come up with a "true find" in terms of absorbtion - with NRC numbers. The material needs to be common, non-toxic, inexpensive, and have a decent NRC. Making something out of a combo of such materials would be good too.


I just thought it might be cool to get the acoustical geniuses out there to stretch those minds a bit and think out of the box.With the obvious talent assembled throughout this thread, I'm betting some really interesting ideas might come to light...



I am in Southern Illinois by the way... Also, why would I have to remove the facing off the ceiling tiles? I assume the NRC of .55 is as installed (in a ceiling) which would have the facing intact and towards the room. So what would be the difference draped in GOM and facing out from the wall?


Thanks guys,

Doggy


----------



## ebr

Actually, I think that NRC rating for the ceiling tiles assumes a 16" airspace above (behind) them...


Stuck flat on a wall, I don't think they do that much.


----------



## Terry Montlick




> Quote:
> Originally Posted by *rudedoggy* /forum/post/0
> 
> 
> Actually guys, I was hoping someone could point out some more novel materials rather than the fiberglass route.
> 
> 
> The challenge is to find common materials (ie packing styrofoam, pillow stuffing, ball of tape - I don't know...) and come up with a "true find" in terms of absorbtion - with NRC numbers. The material needs to be common, non-toxic, inexpensive, and have a decent NRC. Making something out of a combo of such materials would be good too.



Doggy,


Acousticians have tried just about everything over the years. What works ideally well are thick, fibrous materials that permit air to penetrate. This rules out closed-cell foam and pretty much anything heavy and board-like.


The good news is that there are *lots* of materials that qualify: fiberglass, mineral wool, acoustical cotton, and dense polyester batting. Open-cell foam also works, though not as efficiently so you have to use a thicker layer of it.


I don't think that there are any secret materials to be found at Home Depot or Lowes. Their stuff is pretty ordinary, since it is sold for common, high-volume applications.










Regards,

Terry


----------



## rudedoggy

Terry - I thought I had heard you mention that a 'dead' room was better for HT(98%). However, another member told me I should avoid carpeting the lower half of my wall because it would make the room too dead...Can you clear this up for me? Do I want it roadkill dead or just critically injured...If dead is better, shoudln't the carpet be ok then?


P.S. I also was thining of putting some traps in the back two corners. and a off/on mix of batting/duct liner in boxed squares above the chairrail....


Thanks,

doggy


----------



## BasementBob

rudedoggy:


There's a few insulation contractors in Illinois listed here
http://www.bobgolds.com/InsulationContractors.htm 



> Quote:
> avoid carpeting the lower half of my wall


 http://www.bobgolds.com/AbsorptionCoefficients.htm 

lists

1" linacoustic 0.04 0.26 0.69 1.00 1.07 1.02


I chose that because several Dennis Erskine theatres seem to have 1" linacoustic on the lower half of 3 walls (left, right, rear).


That's read, for 1" linacoustic:

near 125hz has an absorbtion coefficient of 0.04

near 250hz has an absorbtion coefficient of 0.26

near 500hz has an absorbtion coefficient of 0.69

near 1000hz has an absorbtion coefficient of 1.00

near 2000hz has an absorbtion coefficient of 1.07

near 4000hz has an absorbtion coefficient of 1.02


1.00 is sort of 100% absorbtion. 0.00 is sort of 0% absorbtion. (it's not a percentage, it's the results of a test, so you can get values like 1.50 without much problem, but anything around 1.00 is about as good as it gets)


A broadband absorber, to me, is one that has 1.00 absorbtion from 125hz through 4000hz.


Carpet.


2291 Floors, 10 mm soft carpet on concrete Ref. Dalenbäck, Datensatz der CATT-Software, November 2000. Data-Category in CATT: CARPET_SOFT, C: Floors, D: 10

0.09 0.08 0.21 0.26 0.27 0.37


506 6mm pile carpet bonded to closed-cell foam underlay (Ref. 18)

0.03 0.09 0.25 0.31 0.33 0.44


2006 Carpet heavy, on concrete Ref. Harris:Handbook of Acoustical Measurements and Noise Control, McGraw Hill 1991

0.02 0.06 0.14 0.37 0.60 0.65


Two things you'll notice about carpet:

a) it's much less absorbant than linacoustic,

b) it's very unpredictable absorbtion depending on what kind of carpet you use


Multiplying absorbtion coefficients, by square footage, gives absorbtion in Sabins.


Everything in the room -- couches, people, cats, walls, whatever --

a) absorbs some sound (how much is frequency dependant as well as material)

b) reflects some sound (how much is frequency dependant as well as material)

c) transmits (through) some sound (how much is frequency dependant as well as material)


The goal is for each frequency to have the sum of the Sabins in the room, be about equal. That is the Sabins at 4000hz, be about the same as the Sabins at 63hz.

Another goal is to have the right number of Sabins (to many and the room is too dead, too few and the room may be echoey).


Wierd sounding rooms are ones with lots of HF absorbtion, but little or no MF or LF absorbtion, or have the absorbtion in the wrong places giving reflection problems that affect speach inteleigibility and imaging.


----------



## bpape

Doggy. I believe what was said was that you shouldn't carpet the bottom of the walls and put batting on the top as the room would be too dead AND UNBALANCED. It would IMO have too much HF absorbtion and not enough in the mids/bass.


As for the materials, unfortunately, finding a non-fiberglass material that is cheap is almost impossible. To get enough high density batting is going to cost you. Acoustical cotton can be reasonable in some cases. Mineral wool has some of the same chemicals you're trying to avoid as fiberglass, foam is either more expensive or not worth much depending on the quality of the foam.


----------



## rudedoggy

Has anyone even used Autex Quietstuf or rigid duct liner? Is it even available in the U.S? If so where?


Thanks,

Doggy


----------



## bighoot

Is it possible to design a wall so that it would absorb lows mids and highes simular to the way they did on the DIY show..... except only drywall every other stud pocket and fill the other pocket with say oc 703 and covering with GOM leaving a 6-8 inch pocket of dead space behind the 703 panels. (sorry if I am showing my ignorance on this subject. but I am trying to understand the best construction methods BEFORE is cover my walls in drywall)

Not sure if this would work or not. If not what would. I have approx 6" behind the studs before you get to the styro foam covered concrete walls on 3 sides and 8" to the drywalled forth wall. (basically a room in a room.)


----------



## bpape

You can certainly design treatments into the wall structure. If you're going to leave the drywall off of A VERY FEW stud cavities, then the back side of those cavities will need to be drywalled or you'll lose your isolation.


Also, bass absorbtion is best done at the end of the boundaries. The wall is certainly at the end of one boundary and a little of it is at the then of a second. Corners are at the end of both and the tri-corners are at the end of all 3. Those are the most efficient places to provide bass control.


----------



## bighoot

So it sounds like the best solution is going to be fiberglass batt insulation in all stud caveties covered by drywall and I see there are pre packeged room treatments that would have tri-corner base traps in the upper corners of all 4 corners and gom covered pannels for the first and second reflective points for the side walls all for less than 400.00 (this seem like a great deal to me). My next problem is I have a beam 6x8 that spand the width of my room at about 9 1/2 feet fron the front wall. will I need to treat the corners on the front and back side of the beam. ( it is covered in drywall ) or can I get by withe the four room corners ant the front 2 heam corners.


----------



## bighoot

A question on front wall treatment. I am usin all inwall speakers. so how do i treat my front wall if the speakers are in wall. the front wall is 12 x 7 the screen is 100in. and the left and right speakers are just outboard of the screen. the center channel is below due to low celing height. Need some help please.


----------



## bpape

For the front wall, treat around the speakers to leave them exposed. It can actually work quite well with them in-wall and all of the wall treated.


Don't worry about the corners around the beam. Deal with the 4 room corners if you can - and don't forget that you have 4 other corners you can also use - the ones that run horizontally at the wall/ceiling intersections.


----------



## Borky

Has anyone ever purchased this kit: http://www.sweetwater.com/store/detail/RoomDST36B/ ? It seems like an inexpensive way to lightly treat my HT/music listening room at home and make things sounds better. Also, what's the difference between panels that are flat and those that have wedges? I really don't know anything about this acoustic treatment stuff, but I would like to get some general understanding.


----------



## BasementBob

Borky:


I think of absorbers as tools to meet a goal.

I have no opinion on the suitability of anything mentioned in this post for your room.


Your 'sweetwater' link is actually this product:

Auralex Roominator 36 (contains 18 Charcoal Gray DST-112 panels and 18 DST-114 panels). http://www.auralex.com/sound_control...ontrol_D36.asp 


Absorbtion coefficients for those two are:

DST-112: 0.12 0.27 0.54 0.71 0.83 0.99

DST-114: 0.16 0.26 0.57 0.75 0.90 1.00


They are 1'x1' panels, so that's 36 ft^2 of surface area, for $139, or $3.86 / ft ^2.


vs


1" linacoustic: 0.08 0.31 0.64 0.84 0.97 1.03

2" 703: 0.17 0.86 1.14 1.07 1.02 0.98

4" 703: 0.84 1.24 1.24 1.08 1.00 0.97


2" 703 is about $0.75 / ft ^2, but probably needs covering cloth and time to build and mount.


4" 703 is about $16 per 2'x4'x4" panel, and you can buy a wrap kit for $30 (TeaBagz), so that's $46 / 8 ft^2, or $5.75 / ft ^2 -- but you get 7 times the absorbtion at 125hz with that (0.84 / 0.12 = 7), and you can make corner traps out of them for bass absorbers. GoM as covering may be cheaper per ft^2 than TeaBagz, but I haven't checked prices on GoM lately. GoM is more work and a better look.


----------



## Borky

Do you have any links for the above mentioned acoustic panels?

Also I understand Teabagz is just something to put the material inside, sort of a liner? Why do I need that, can't I just use the panels on the walls?


----------



## BasementBob

Borky:


> Quote:
> Do you have any links for the above mentioned acoustic panels?



Linacoustic is manufactured by Johns Mansville and is acoustical HVAC duct liner, but works well on walls.

703 is a rigid fiberglass product made by Owens Corning.

Neither is really an 'acoustical panel' in the sense of a finished product, but rather a building material, thus happens to be relatively inexpensive, yet works well.

For a decent list of typical alternatives (other than and including linacoustic and 703) please see
http://www.bobgolds.com/AbsorptionCoefficients.htm 



> Quote:
> Also I understand Teabagz is just something to put the material inside, sort of a liner? Why do I need that, can't I just use the panels on the walls?



In the case of the auralex foam product you found, you can just glue them to the walls and you're done. Same with auralex MegaLENRD's. Being able to just place them and you're done, has a lot of appeal to a lot of people.


In the case of 703, if you bump into it you may get fiberglass into the air, and if you hang it over your head you're almost certain to get more dust on everything in the room than you're accustomed to -- unless you cover it. It's relatiely easy to rip off a bite sized chunk, so I wouldn't want babies crawling near it for a variety of reasons.

In the case of linacoustic, as duct liner, it is treated so that even a stiff wind won't blow fiberglass into the air, but the black twoards-the-room side isn't pretty, so most people cover it with something that's pretty.


----------



## Ethan Winer

Borky,


> Why do I need that, can't I just use the panels on the walls?


----------



## ebr

I have an odd SBIR question that I hope you acoustic gurus can shed some light on.


The front of my room will have a "notch" in it due to the foundation walls that make up the front part. Like this:

Code:


Code:


-----------------------------
          |                              |
          |                              |
---------                                |
|                                        |
|                                        |

The notch will never be visible because it will be hidden behind the proscenium wall. However, this means I cannot put the speakers where I normally would - out wide behind the proscenium wall.


In another thread, it was pointed out that putting my L/R speakers behind my screen (as I planned) would create a very narrow angle to the listening position and be detrimental to the imaging of the front sound field.


So, my question is, if I were to put a speaker here (where the 'S' is):


Code:


Code:


-----------------------------
          |                              |
          |                              |
---------  S                             |
|                                        |
|                                        |

Would I have SBIR issues (the face of the speaker would be in front of the side wall, but the speaker body would be right up against it). Or, other issues due to having one side of the speaker right up against a boundary and not the other?


----------



## Borky

I wouldn't be opposed to buying the fiberglass insulation like the 703, but problem is, I called a few stores in my area that the main OC site claims are dealers and they carrying nothing like that.


Also, does anyone know the absorbtion coefficients for these panels: http://www.envisiononline.net/acousticpanel.html ?

I don't see them anywhere on the site.


----------



## BasementBob

Borky:


There's a couple of stores in New Jersey listed at
http://www.bobgolds.com/InsulationContractors.htm 


I think that:

a) http://www.gikacoustics.com/ 

b) Auralex TrueTraps ( test data )

c) and of course ethan's http://www.realtraps.com 

sell ready made acoustic panel absorbers, and perhaps more importantly list absorbtion coefficients for them.


----------



## tonybradley

Hi Guys. I have a question about treating my side walls with OC703 1" panels at the First Reflection points.


I am very clear that I need to use Unfaced fiberglass. However, the ONLY place in my area where I can purchase 703 (found on the spi website) does not carry Unfaced boards. They can order them for me, but I have a feeling it will be more expensive. What will be the effect of using Foil or Paper covered (I don't know which acronym goes with which one FSK, etc.) fiberglass panels, with the paper or Foil facing the drywall? I plan on just covering these with Muslin or GOM and gluing to the back of the panel.


If someone could let me know, I'd greatly appreciate it. I'm going to have the company give me a price quote on the Unfaced (and faced depending on what is said here).


----------



## ebr

Any thoughts on my delimma?


----------



## Terry Montlick




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Hi Guys. I have a question about treating my side walls with OC703 1" panels at the First Reflection points.
> 
> 
> I am very clear that I need to use Unfaced fiberglass. However, the ONLY place in my area where I can purchase 703 (found on the spi website) does not carry Unfaced boards. They can order them for me, but I have a feeling it will be more expensive. What will be the effect of using Foil or Paper covered (I don't know which acronym goes with which one FSK, etc.) fiberglass panels, with the paper or Foil facing the drywall?



No difference at all.










If the faced insulation was the other way 'round, there would be a big difference. You would no longer have as efficient a wide-band absorber, but one better at absorbing low frequencies.


Regards,

Terry


----------



## tonybradley




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> No difference at all.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If the faced insulation was the other way 'round, there would be a big difference. You would no longer have as efficient a wide-band absorber, but one better at absorbing low frequencies.
> 
> 
> Regards,
> 
> Terry



Thanks Terry, that's great to hear. Let me ask you this. I really like nice shapes and overlayed effects from makers, such as kinetic, etc. However, I want my panels to be DIY. I was thinking of this, and you tell me if this would be a big No No!


Use a piece of MDF either painted or covered with fabric at the First Reflection Points. On top of the MDF, I would have a 1" rigid board (OC703) covered in fabric. That would give me a nice 3D look to my panels without Over Absorbing by using (2) 1" panels to create the depth. Would using MDF as a back layer be OK as I'd think that would be similar to the panel attached to drywall?


----------



## Terry Montlick




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Thanks Terry, that's great to hear. Let me ask you this. I really like nice shapes and overlayed effects from makers, such as kinetic, etc. However, I want my panels to be DIY. I was thinking of this, and you tell me if this would be a big No No!
> 
> 
> Use a piece of MDF either painted or covered with fabric at the First Reflection Points. On top of the MDF, I would have a 1" rigid board (OC703) covered in fabric. That would give me a nice 3D look to my panels without Over Absorbing by using (2) 1" panels to create the depth. Would using MDF as a back layer be OK as I'd think that would be similar to the panel attached to drywall?



An MDF back should be no problem when covered with rigid fiberglass. Just make sure that it is fastened to the wall firmly and doesn't rattle.


You mean "either painted or covered with fabric" at the exposed sides, right? Otherwise, I don't understand.


- Terry


----------



## tonybradley

You got it. In simplistic design, the MDF will be a larger rectangle and the Fiberglass panel will be a smaller rectangle attached to the MDF. It will just give my panels a layered effect to look nicer (IMO)


----------



## BasementBob

tonybradley


> Quote:
> What will be the effect of using Foil or Paper covered (I don't know which acronym goes with which one FSK, etc.) fiberglass panels, with the paper or Foil facing the drywall?



Acoustically, it'll be just fine.

Structurally it might be easier to support, or even glue, the facing to the wall.

If you covered your entire wall in them, then you'd have humidity/mold issues, but just a first reflection point, or even half the wall, shouldn't be a problem IMO.


For 1" first (and early) reflection points, go ahead and buy whatever's cheapest, such as faced 703.


I presume you're covering them in something eventually.


----------



## Ethan Winer

Tony,


> What will be the effect of using Foil or Paper covered


----------



## tonybradley

Bob and Ethan,


Thanks. I knew I'd want the 'unfaced' portion towards the room. I just wasn't sure if there would be some wild effect with the foil or paper against the drywall.


----------



## guymon

I am using OC 703 on side walls up to ear level. On floor I have concrete and rear area is on a 12 inch riser. When I carpet should I use padding under or glue carpet down directly to cement and riser?


----------



## ChrisWiggles

I would use padding because it makes the carpet more comfortable and last longer. I don't think it's going to have too much of an impact on deepening the absorption of the carpet, it won't absord much bass because it's so thin, so I don't think I would say that acoustics is something I'd consider when deciding about carpet padding. But I'd certainly use very thick padding(as thick as you can get) on cement because it makes the space more comfortable over cement without subflooring. You might not need as thick padding on the riser if you wanted to save some cash.


----------



## Westshorestudios

In a recent thread I asked about faux fur covered fiberglass for acoustical panels (safari theme type room). Here is a related, but different question:


One of my subwoofers will be in a cabinet / enclosure that is built into the wall, so that the front of the sub will be flush with the wall (and all space around the sub packed with insulation so that the enclosure does not result in boominess).


The sub enclosure is located directly opposite where one of my acoustical panels will go. I would like for the room to appear symetrical in regards to the treatments on the walls. Accordingly, instead of a cabinet front with speaker grill cloth covering the sub woofer enclosure, I'm thinking of covering the sub enclosure's opening with the same type of faux fur fabric that will cover the acoustical panel on the other side of the room. However, I don't want to do something that distorts the sound from the sub.


The faux fur fabric can be blown through. There is about the same resistance in doing so as blowing through 2 layers of GOM. The "fur" is about 1/3" - 1/2" long.


My thought is that since the sub (Klipsch thx ultra 2 sub) will only be playing from around 15hz up to somewhere between 80hz and 150hz (depending on where it is set on installation, calibration, etc.), the faux fur fabric would not have any discernable effect on these frequencies, right???? Can anyone confirm that I'm ok doing this?


Thanks much.


----------



## Westshorestudios

I'm confused over how to treat my rear wall and would like to hear some acoustical treatment expertise. My room is 15'9" wide and 19' long. (The rear wall and the front / screen wall are the 15'9" walls). I have 2 rows of seats. My rear row of seats is about 6" - 12" from the rear wall. I have a 7.2 setup with side surrounds and 2 rear surronds.


My question is whether, with the rear seats so close to the rear wall, should I treat the wall with absorbtion or diffusion or some combination of both?


Thanks.


----------



## myfipie

Westshorestudios,


I myself would go with abortion on the back wall. Diffusion, IMO, really is good in a large room and with the back sets so close the the back I can't see how diffusion is going to work for you.


Glenn


----------



## pandasys




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Westshorestudios,
> 
> 
> I myself would go with abortion on the back wall.
> 
> Glenn



I think that is illegal in most states.


Happy New Year!


----------



## myfipie

Oh God Eric, way to much partying last night!!!!!!! Sorry about that. "Absorption"


----------



## mrohde

Hello,

I am new here I know I am about to ask a question that has already been asked (can't seem to find it)


Insul-Shield, I called the manufacturer and they told that they did not make that product anymore. I called to see where I could buy it in my location (Columbus, OH).

So, what are folks using in its place?


Thanks


----------



## ebr

Any number of things are comparable. From JM - the Linacoustic RC coated black is what I used and is very similar to the old InsulShield.


----------



## pandasys




> Quote:
> Originally Posted by *mrohde* /forum/post/0
> 
> 
> Hello,
> 
> I am new here I know I am about to ask a question that has already been asked (can't seem to find it)
> 
> 
> Insul-Shield, I called the manufacturer and they told that they did not make that product anymore. I called to see where I could buy it in my location (Columbus, OH).
> 
> So, what are folks using in its place?
> 
> 
> Thanks



Owens Corner 703 unfaced 1" is popular. I bought an bonded acoustical cotton equivalent. I'm not using the cotton on a wall and it's a little more money.


----------



## Tweakophyte

Speaking of JM...


Is the Johns Manville Spin-glass board basically the same thing as the OC 703? I am looking at the 2" thick 815 (3pcf) because I can find it locally and in-stock.


The specs look different here:
http://www.bobgolds.com/AbsorptionCoefficients.htm 

FR ....125hz 250hz 500hz 1000hz 2000hz 4000hz NRC

815...0.27 0.91 1.11 1.09 1.09 1.09 1.05

703...0.17 0.86 1.14 1.07 1.02 0.98 1.00


----------



## Tweakophyte

...another quick one... I think...


If I mount the rigid fiber board (like 703 or the JM 815) on a thin piece of wood for support, then space it away from the wall, will I still get the benefit of absorbing lower freqencies? Also, if I take one of these panels and put it in a corner, will it work to absorb deeper bass?


This way is easier and cheaper than making a frame, but I am not sure if I need the back of the fiber board to be open.


----------



## mleineke




> Quote:
> Originally Posted by *mrohde* /forum/post/0
> 
> 
> Hello,
> 
> I am new here I know I am about to ask a question that has already been asked (can't seem to find it)
> 
> 
> Insul-Shield, I called the manufacturer and they told that they did not make that product anymore. I called to see where I could buy it in my location (Columbus, OH).
> 
> So, what are folks using in its place?
> 
> 
> Thanks



FYI, I recently (about 6 weeks ago) purchased InsulShield IS300 unfaced 2x4 1" thick panels special ordered from Menards.


Mark


----------



## bpape

703 and 815 are very similar.


If you mount either on a board then there is no benefit to spacing it off the wall. If you need to mount it to something, just leave the perimeter of the board so most of the fiberglass is not backed. Then you'll benefit from the spacing.


----------



## Tweakophyte

When I am treating my front, is it generally effective to just have the 2" (OC703 or JM815) basically flush with the wall, or should I go for some spacing.


My thought is for the front wall and first reflection points, I can take the easy route and use the plywood. When I get to the corners I will either double up (and make a 4") or build a frame and create some space.


Not that this gets repeated a lot, but if I am going for bass trapping in the corners using a panel, it is better to double up to make a 4" panel, or space a 2" panel 2" away from the wall? In that case if I have foil scrim, I assume it faces the wall for general absorbtion and faces the room for "bass only"? How about for the front corners versus the rear?


They should also call this the acoustical treatment validation thread










Thanks again,


----------



## Westshorestudios

Is 86 cents per foot an ok price for OC 703?


----------



## BasementBob

Westshorestudios:

For 2" thick 703 material, I've seen prices over the past two years between $0.50 and $1.50US per square foot.

My rule of thumb that for 2" thick material, once you've found stuff for less than $1 per square foot, stop looking -- it's not worth the effort any more.

So, 86 cents is an ok price per square foot of OC 703 2".


----------



## BasementBob

Tweakophyte:


> Quote:
> If I mount the rigid fiber board (like 703 or the JM 815) on a thin piece of wood for support, then space it away from the wall, will I still get the benefit of absorbing lower freqencies?



It depends on lots of things. I'd try to stick with one of the known and tested designs -- otherwise you're just hoping and who knows what you'll end up with.


If you have

- porous absorbtion, then wood, then a 2" air gap, then your wall (gypsum/drywall)

worst case you'll get a resonance that will reduce your soundproofing.


Generally speaking, wood is a reflector.

If you have wood in a sealed enclosure, it can be a membrane trap.

FRK (basically paper or foil) on the outside of fiberglass certainly reflects, but is light enough that it lets some sound through.


Ignoring what you might get for absorbtion -- why would you cover the entire back with plywood and then space it from the wall? Are you trying to hold up the fiberglass?

I'm trying to figure out how and why you're mounting the fiberglass to this piece of floating plywood. Why not just have the four corners. And if you're gluing the 703 to the wood, could you fill the wood with holes (i.e. 80% holes, 20% wood). Why not just six spacers (2"x4x"4") and use impailing clips on them to hold up the fiberglass. (BTW, I've never heard of anyone glueing fiberglass to wood. Usually they are some kind of nailed/clipped, or held by gravity, or a frame, or spring ties. Mine were friction fit into an exoskeliton frame)


----------



## Tweakophyte

Hi Bob-


Thanks for the response. The reason for the plywood backing is to give the fiberglass additional structural support, to give me something I can staple fabric to, to make it easier to hang, and to save a few bucks and time compared to making a frame (the 1/4" board is about $3.50 and is already 2'x4'). I would take the fibreglass panel and wrap it with fabric to attach it to the plywood. I was thinking I would use these types of panels for general absorbtion, hung directly on the wall.


I would use another approach for bass trapping in the corners. I am thinking of 2" or 4" of fibreglass in a frame, possibly spaced away from the wall. For example, I could use a 1"x3" frame with 2" of fiberglass and, hung flush on the wall have 1" of spacing for the fiberglass, itself. I could also use the foil scrim (availble to me from the same supplier) facing the room, away from the room, or in the middle of two, 2" pieces of fiberglass in a 4" frame.


I have not played with any type of rigid fiberglass, so I am not familiar with how it would stand on its own with. Do you need a frame (either for support or to attach it to a wall)? How easy does it dent? Can you attach fabric directly to it? I have young kids and a wild, yellow lab, keeping them whole is a concern, as is having exposed nails (for mounting on a wall).


I've seen some simple frames made from 1"x2" and L-brackets... the problem is I have no electric cutting tools. Any other money saving shortcuts here?


One more clarification. I won't be able to just cover the whole front wall, so I was planning on hanging a few panels for absorbtion on the front wall and first reflection points. I was also planning on bass traps (i.e. thicker than 2" or spaced away from the wall) in the rear corners, and maybe the front corners. Is that okay?


Thanks again,


----------



## Tweakophyte

Bump... any comments on my post above?


Thanks,


----------



## BasementBob

Tweakophyte:


I'm a DIY guy with carpentry/plumbing/electrical/welding skills -- so I tend to think in those terms.



> Quote:
> I have not played with any type of rigid fiberglass, so I am not familiar with how it would stand on its own with. Do you need a frame (either for support or to attach it to a wall)? How easy does it dent? Can you attach fabric directly to it?



Without a frame you can wrap it up like a christmas present in fabric. If it's against the wall you can lean gently against it and it won't dent (much), but if you push your finger into it you'll make a hole quite easily. If it's across a corner then leaning against it, or hitting it with a vacume cleaner will sooner or later snap it in two.



> Quote:
> I've seen some simple frames made from 1"x2" and L-brackets... the problem is I have no electric cutting tools.



That might be your best course. Home Depot can cut the wood for you, and you can screw them together. I'm thinking 1/2"x4"x4' and 1/2"x4"x2'1" boards as an outer edge frame, without L brackets. That would create a frame that's got a 2'x4' inside surface. Wrap 2" of 703 (or whatever) in polyester batting (optional), and put that in the front of this frame (friction fit), then wrap the whole frame in any fireresistant fabric you can blow through. The rigid rockwool will keep the frame square, the wood of the frame will keep it stiff, and the fabric may help to pull it together. There is no 'back' to this style. A vaccume cleaner would bounce off the wood. And if anyone falls on it, the 703 will simply push back further into the frame without breaking. It would look something like (but not exactly like) this http://www.bobgolds.com/Absorber/OLD/IMG_0152.jpg 


Any variation you come up with based on skills and parts availability is likely fine.


----------



## tonybradley




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Tweakophyte:
> 
> 
> I'm a DIY guy with carpentry/plumbing/electrical/welding skills -- so I tend to think in those terms.
> 
> 
> 
> Without a frame you can wrap it up like a christmas present in fabric. If it's against the wall you can lean gently against it and it won't dent (much), but if you push your finger into it you'll make a hole quite easily. If it's across a corner then leaning against it, or hitting it with a vacume cleaner will sooner or later snap it in two.
> 
> 
> That might be your best course. Home Depot can cut the wood for you, and you can screw them together. I'm thinking 1/2"x4"x4' and 1/2"x4"x2'1" boards as an outer edge frame, without L brackets. That would create a frame that's got a 2'x4' inside surface. Wrap 2" of 703 (or whatever) in polyester batting (optional), and put that in the front of this frame (friction fit), then wrap the whole frame in any fireresistant fabric you can blow through. The rigid rockwool will keep the frame square, the wood of the frame will keep it stiff, and the fabric may help to pull it together. There is no 'back' to this style. A vaccume cleaner would bounce off the wood. And if anyone falls on it, the 703 will simply push back further into the frame without breaking. It would look something like (but not exactly like) this http://www.bobgolds.com/Absorber/OLD/IMG_0152.jpg
> 
> 
> Any variation you come up with based on skills and parts availability is likely fine.



Bob, after looking at the coefficient chart, I noticed that R-11 Unfaced (On Wall) 3.5" has better absorption numbers than the 1" OC703. I want to make sure I'm reading this correctly. Could I make a frame and use R-11 with pollyester batting overtop of it, wrapped in fabric and get the same/better results than 1" 703? Only thing is, the panels would be about 4" thick instead of around 1". If I were to compress some of the fluffy fiberglass, would that negate it's properties at 3.5" thick?


----------



## bpape

Basically, the reason you're getting better numbers is because of the thickness. If you compress it, you'll lose that and end up with basically the same thing as 703 (if you take it to about 1.5" thick).


Remember that the determining factors for how deep and absorber will reach is a combination of thickness, density, and mounting position in relation to a boundary. You can go lower by increasing any or some combination of those factors. For example, 4" of 703 will do a better job down low than 2" of 705. 2" of 705 will do a better job spaced 2" off the wall than mounted flat to the wall, etc.


----------



## tonybradley

Thanks. I'm just trying to look at all my options. The only place in my area that sells Rigid Fiberglass boards has a minimum you have to buy, which I don't need that many.


----------



## ebr

Brian - in that vein - which is better (absorbs more down low):


2" spaced 2" from the wall or 4" flat against the wall?


----------



## Tweakophyte

Hi-


I am re-reading Ethans's paper and I have a question. When putting a panel across a corner for bass trapping, is it better or worse to also have a panels along the walls in that corner? I was originally planning on putting 4" of 703 (actually JM equivalent) in a frame on each of the corner walls for bass trapping. The article shows a 705 panel spanning the corner with nothing behind it.


Should I build a 4" panel to span the corner, then to 2" traps along the walls? I am not sure I can give up that much space, which is why I was going for two on the wall in the corner.


Any thoughts?


Thanks,


----------



## bpape

ebr - a solid 4" will outperform the 2" spaced 2" assuming the same material.


Tweak - If you don't mind spending the extra money, make it a 6" panel spanning the corner - that's a much better, more effective use of the matieral.


----------



## Ethan Winer

Tweaks,


> When putting a panel across a corner for bass trapping, is it better or worse to also have a panels along the walls in that corner? 
The article shows a 705 panel spanning the corner with nothing behind it.


----------



## Tweakophyte

Thanks guys.


I have another one. I looked at some material... burlap will not work for me. Many of the nylon materials are too sheer. Is felt okay? Are there any other good, inexpensive materials that the wife (and I) will like? It looks like speaker cloth is $5-6/yard but at 30" wide, which compares to the ~$3/ yard I was looking at at 72" wide (i.e. 4x the cost).


I will use the same fabric for both the front wall, general abosorbers and the bass traps.


Also, for a 4-6" thick panel spanning the corner at 2', how deep will I have useful bass absorbion? What if that same panel was only 1' wide?


Thanks again,


----------



## myfipie




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Thanks guys.
> 
> 
> I have another one. I looked at some material... burlap will not work for me. Many of the nylon materials are too sheer. Is felt okay? Are there any other good, inexpensive materials that the wife (and I) will like? It looks like speaker cloth is $5-6/yard but at 30" wide, which compares to the ~$3/ yard I was looking at at 72" wide (i.e. 4x the cost).
> 
> 
> I will use the same fabric for both the front wall, general abosorbers and the bass traps.
> 
> 
> Also, for a 4-6" thick panel spanning the corner at 2', how deep will I have useful bass absorbion? What if that same panel was only 1' wide?
> 
> 
> Thanks again,



As far as fabric goes, if you are wanting to hit the hf also then any breathable fabric should be fine..


It is hard to say how much better 6" is with out testing it, but only using 1' wide panels would not work very well. One reason is you need surface area coverage for the room. Second the space behind a 1' panel straddling corners is not enough to efficiently hit the low end.. Stick with 2' panels..


Glenn


----------



## tonybradley

I apologize for all the questions...just trying to get all the info I can. I've pretty much decided on using OC703 panels for the treatments in my room. I was going to place them vertically at the First Order Reflection Points. The more I read, I'm wondering if it would be better to hang Vertical, or Horizontally? If Horizontally, they would only be 2' high and 4' wide. That would probably hit both points on one wall (possibly). But, would I want to mount them just above my outlets and go 2 feet up, or mount them higher? If doing Horizontally, I was thinking of wrapping about 4 or 5 panels for each wall and attaching them horizontally from front to back. Would this be nonsense? Should I just stick with hanging panels vertically at the reflection points?


----------



## rudedoggy

I could us some expert advice... I am planning on purchasing soem accoutic foam and some bass traps, but I have a couple of questions first.


1) If I would like to take the accoustic foam - wedge shaped ruffles - and use it at the top of my theatre aong the wall and along the bottom along the floor - like crown molding, will I be shorting my absorbtion? I was thinking about 12" section coming down from the cieling and a 18" to 24" section near the bottom. This "bordering" would be consistent on the 2 side and back walls. I wil also use it in conjunction with corner foam bass traps... Does this sound like a workable solution or will the fact that the middle of the wall is purely drywall ( and some boxed poster) hurt the overall accoustics?


2) I have 4 - 6" columns I made along the side walls. Would it make sense to put 6" bass traps along the sides (the corner area) of each side of each column? Or will the use of 12" traps from ceiling to floor in the back corner of the room be sufficient?



I would appreciate any comments you all might have on the subject and on the subject of placement..


Thanks,

Doggy


----------



## bpape

Using any treatment just along the top and bottom will still help with decay times somewhat but ignores the reflection points which are most critical and are at ear level approximately.


For the corners, you'll want whatever you can spare. The wider, thicker, and deeper the better. Normally you would do something like straddle a 4" thick material at 45 degrees across the corner floor to ceiling. You can also use the horizontal corners where the wall and ceiling meet if you can't lose the floorspace or have door issues.


Lastly, I'd strongly recommend looking at something other than foam. Don't get me wrong - the Auralex brand is pretty good. The rest are not worth using IMO. For bass absorbtion, I would recommend using OC fiberglass (or equivalent), mineral wool, or acoustical cotton. Dollar for dollar, they'll all do a better job for less money than the foam for bass absorbtion purposes.


----------



## Tweakophyte

Yesterday I picked up my first batch of JM814 (an OC703 equivalent). I took a few pieces out to play around with. When I was done, I put all five, 2" panels back in the plastic bag and stuck the whole thing in the corner. I had been playing an older Orbital track that has several long, deep, reverse bass sweeps in it. That track has always exposed the FR of the room (i.e. louder and softer portions of the sweep).


Anyway, with the panels shoved into that rear corner there was a night and day difference! The sweep played very flat until I would guess about 40hz. This was just with 4' (tall of stuff in ONE CORNER!


----------



## Tweakophyte

Now my questions...

I have 2" thick material. I will build frames and wrap them with felt.

- For the front wall I am thinking of building either a 2" or 3" deep frame, and mounting it on the wall. The 3" frame would allow for a 1" air gap. Which configuration is better? If space is a concern, is it worth making the frames even deep (i.e. 4" frame with 2" of material and 2" of air gap)?


- For the side walls I am thinking of either a 3" or 4" deep frame mounted on the wall to cover the first reflection points. This would have 2" of material and an air gap. Comments?


- Inside of my shadow box (see my gallery) I am thinking of doing the same (3" or 4" frame). Space is a small concern here.


- Is 2" of material, wrapped and mounted flush with the ceiling okay, or should I work in an air gap?


- I had a great, initial result from bass trapping in only one corner with 5 pieces of material. How important is symmetry here? My front-right and rear-right corner could hold a 4' tall trap like that fairly easily. My inital plan for a bass trap is a 6" deep frame with foil scrim facing the room. What if I only trapped one corner? What if I did only the right corners? Would it be better to fill one corner (i.e. with the 5 peices) or do two corners with thinner traps. In other words, is it better to have one really thick trap or two thinner traps?


- What is the best way to mount these frames on the wall? I was thinking of putting two nails in the wall and hanging the frame on there. That would pierce through some material that I'll wrap behind a bit. Any other ways? Is it okay to mount these flush to the wall? (If not, I'll probably opt for the thinner version of the frame.)


Thanks!


----------



## myfipie

I think any of the ways you are thinking of doing this is fine, but here are a few things just to point out.


>Now my questions...

I have 2" thick material. I will build frames and wrap them with felt.

- For the front wall I am thinking of building either a 2" or 3" deep frame, and mounting it on the wall. The 3" frame would allow for a 1" air gap. Which configuration is better? If space is a concern, is it worth making the frames even deep (i.e. 4" frame with 2" of material and 2" of air gap)?
- For the side walls I am thinking of either a 3" or 4" deep frame mounted on the wall to cover the first reflection points. This would have 2" of material and an air gap. Comments?
- Is 2" of material, wrapped and mounted flush with the ceiling okay, or should I work in an air gap?


----------



## Tweakophyte

Glenn-


Thanks for your comments. Regarding the spacing off of the wall to let the sound in, is there any kind of minimum to be effective? I'm really talking about the difference between a crack (say 1/4") and an inch or two.


I am thinking of getting some rubber feet and tapping them into each corner of the frame for spacing away from the wall.


Thanks again,


----------



## myfipie

>Thanks for your comments. Regarding the spacing off of the wall to let the sound in, is there any kind of minimum to be effective? I'm really talking about the difference between a crack (say 1/4") and an inch or two.


----------



## Tweakophyte

Glenn-


Thanks again for the comments. I wandered around Lowes yesterday and found some glides you put on the bottom of a chair. These are designed to recess into a hollow portion of the chair, so they are 1/2" thick instead of the standard 1/4". From there I am going to add some thick felt (also used for glides) and the net spacing off of the wall should be about 3/4".


Ethan, if you are reading this, for the purpose of letting the sound in from the sides, how much is enough? Is 1/4" too little? How about the 3/4" solution I am looking at?


Because of that additional spacing and the space constraints, I think I'm going with 2"x3" fir for the frames. That should net me about a 1 5/8" air gap for the 2" of rigid fiberglass. Silly question, but does having a non-integer distance as an airgap reduce the effectiveness of the panel? If it does, I can use 3 1/2" MDF, which is a true 3 1/2" and net out to 1/2" of spacing, which would put a 2" gap for the rigid fiberglass.


PS Is "master of all acoustics IN THE WORLD" meant to be read in a monster truck announcers voice?


----------



## jponder209

I'm planning to build some pannel traps. Is there a way to figure out the sabens for each trap?


John


----------



## kwill

more bass trap questions:


In my HT room, I have 2 15inch Titanic MKIII subs on opposite sides of the room in the corners. I only have three corners in the room, as one opens into a hallway. This leaves me with one open corner for a large trap, or I could move the subs out from the corners a little and have one large trap, and two smaller traps. I found a local dealer who stocks 2 by 4 foot JM814 (similar to OC 703)

To the questions:


1. Will a trap directly behind the sub (within a few inches) adversely affect it's performance?


2. How exactly does the surface area of the material come into play? It seems to me that a hollow core trap would be less effective than a "superchunk" type. If I took 4 of the 2 inch thick, 2x4 foot panels and cut the material into one foot sections and stacked them in the corner to 64 inches, would this be more, less, or equally as effective as any other configuration with the same amount of material? I am assuming that the low frequency waves, due to their omni directional nature, will enter the center panels in the stack, just as they would the panels on the top and bottom. Is this right?


3. In a stacked corner configuration, is there a need to seal the top and bottom of the traps?


4. Has anyone used bass traps behind Magnepan 1.6 or similar planar speakers? As it is now, one of the subs is just behind the 1.6. If I add a trap to this corner, it will be within three to 3.5 feet of the speaker. Would this be a problem?


I know, the questions are all over the map, but I am really trying to understand this.

Thanks.


----------



## bpape

No need to seal them.


Bass radiates omnidirectionally so an absorber there should not be a major issue.


Can't say about the Maggies.


As for solid or straddling, the solid has the potential to do a better job down deeper in the frequency range.


When considering where to place bass absorbers, remember that you also have the wall/ceiling horizontal corners that will work pretty much the same as the vertical wall/wall corners. This frees up a LOT more area for you to get the bass under control and also doesn't take up any floorspace and maintains symmetry in the room.


----------



## kwill

Bpape,


Thanks for the reply.


Can you elaborate on this? "As for solid or straddling, the solid has the potential to do a better job down deeper in the frequency range."


Do you mean that the uncut sheats will work better than stacked one foot sections?

If so, can you explain why?


----------



## Tweakophyte

Ethan, any additional comments to what Glenn said regarding the spacers I am considering using? (Others are welcome to add, too.)


Thanks,


----------



## bpape

Think about this...


Your two options are:


- Take 2 of the 2'x4' sheets - 2 thick to make 4" - and set them in the corners straddling it at 45 degrees. You now have 8 sq ft of 4" thick absorbtion facing the room with a 15" or so airspace behind it (variable due to the corner).


- Take 3 of the 2'x4' sheets and cut them into triangles (you'll get 8 equal triangles of 1.4' x 1.4' x 2' from each 2'x4' sheet - so 1 sheet will give you 16" of height). Stack them up in the corner. You'll end up with the same size absorber in the corner BUT it will be a solid piece of absorbtion instead of 4" of absorbtion and 15" of airspace. This puts more of the wave and, more importantly, a reasonable part of longer (lower frequency) waves in the absorbtion at any one time.


The solid has the potential to do a better job at lower frequencies albeit at a 50% premium for the cost of the absorbtive material. The cost for mounting and cloth will not change.


Some people do a mix where they make it solid in the upper and lower tri-corners for a foot or 2 and then straddle the 4" in the middle. Also, for the same 3 sheets if you don't want to do all the cutting and making the slats to hold the stack in place, you can just make a 6" thick absorber in a frame straddling the corner. This will also provide an improvement in extension.


----------



## Ethan Winer

Tweaks,


> Ethan, any additional comments to what Glenn said regarding the spacers I am considering using?


----------



## dennisgg

Hi,



I have a question about bass traps. DIY Network (TV network) had made a Quiktube (4' tall concrete forms in 8:, 10:, and 12" diameters from quikrete company), filled it with sand and put it in the corners for bass traps in their home theater series show. This would be very cost effective to be sure. How effective would this be for a bass trap? Alot of the research I see is using porous ones like fiberglass and a sort of foam rubber. I would really appreciate some help on this. I know that acoustics are a whole science and does'nt have black and white answers, but I would appreciate some guidance on this. Here is the link to their plan:

http://www.diynetwork.com/diy/hi_fam...471072,00.html 





Thank you in advance,




Dennis


----------



## bpape

This has been discussed before. In short - nobody here or anywhere else I hang out has been able to explain how that would even remotely work. The ONLY thing it MIGHT do is to act as a difffusor - but the diameter isn't large enough to work below maybe 100-150Hz or so.


Somehow, someway, a bass absorber has to absorb bass. It can be thick porous material that turns the waves into heat, it can be a tuned absorber where either an air column or a tuned membrane vibrate at specific frequencies and are damped, or it can be an active system wher the inverse of certain waves is generated out of phase to cancel certain frequencies. It can even be hanging panels that literally move when the waves hit them thereby sucking energy from the wave.


The sand filled tube cannot do any of these things. It won't pass a wave, it has no way to vibrate due to being damped with sand, it can't move due to its mass, and has no air column (damped or not) that can be tuned.


Look for another solution.


----------



## Tweakophyte




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Think about this...
> 
> 
> Your two options are:
> 
> 
> - Take 2 of the 2'x4' sheets - 2 thick to make 4" - and set them in the corners straddling it at 45 degrees. You now have 8 sq ft of 4" thick absorbtion facing the room with a 15" or so airspace behind it (variable due to the corner).
> 
> 
> - Take 3 of the 2'x4' sheets and cut them into triangles (you'll get 8 equal triangles of 1.4' x 1.4' x 2' from each 2'x4' sheet - so 1 sheet will give you 16" of height). Stack them up in the corner. You'll end up with the same size absorber in the corner BUT it will be a solid piece of absorbtion instead of 4" of absorbtion and 15" of airspace. This puts more of the wave and, more importantly, a reasonable part of longer (lower frequency) waves in the absorbtion at any one time.
> 
> 
> The solid has the potential to do a better job at lower frequencies albeit at a 50% premium for the cost of the absorbtive material. The cost for mounting and cloth will not change.
> 
> 
> Some people do a mix where they make it solid in the upper and lower tri-corners for a foot or 2 and then straddle the 4" in the middle. Also, for the same 3 sheets if you don't want to do all the cutting and making the slats to hold the stack in place, you can just make a 6" thick absorber in a frame straddling the corner. This will also provide an improvement in extension.




Bryan-


Thanks for the comments. I was, infact planning on using 3 pieces for the rear bass traps. I had considered cutting the material into wedges. If I do my math right, isn't it only 4 triangles per sheet? In that case I would need 6 pieces to make it 4' tall. (Did I do that right?)


I wonder if it would be better to do a 6" thick panel, which would be spaced a little further away from the wall (based on the 2' span of the first panel) or do the thicker, wedge-type absorber that is only 2' tall. How about another variation where there outer-most piece of rigid fiberglass is still 2', and you have two more pieces that get thinner. That might be easier to self-contain.


If I interpreted Ethan's paper correctly, it would be surface area and spacing as factors to consider.


----------



## Tweakophyte




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Tweaks,
> 
> 
> > Ethan, any additional comments to what Glenn said regarding the spacers I am considering using?


----------



## Tweakophyte

One more...


Regarding the bass traps in the corner. Is it better to have two 6" thick 4' tall panels straddling the rear corners, or one 4' tall wedge trap in only one corner. How important is symmetry?


----------



## Ford Prefect




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> 
> If I do my math right, isn't it only 4 triangles per sheet? In that case I would need 6 pieces to make it 4' tall. (Did I do that right?)



Hi, Tweak. I think Bryan's original math is correct. You will only get four 1.4' x 1.4' _squares_ from a 2' x 4' sheet, but each square yields two triangles, making 8 triangles altogether.


/FP


----------



## bpape

If you cut the sheet in half so you have 2 pcs that are 2x2, then cut those ONCE on the diagonal, you end up with 2 triangles that are 2'x2'x2.8' from each of the 2 pieces for a total of 4.


If you cut the same sheet in half and then cut each of those 2'x2' piecs with an 'X' pattern, you get 4 triangles that are 1.4'x1.4'x2' from each of the 2 pieces for a total of 8.


Either way works, just a matter of how big you want the face of the absorber to be and how much wall space you have.


----------



## mmmkam

Accoustically is there any advantage in putting a non-perf screen on a false wall so that linacoustic can be placed on the entire real wall behind it vs putting the screen on the real wall with just linacoustic on the wall around it?


----------



## Terry Montlick




> Quote:
> Originally Posted by *mmmkam* /forum/post/0
> 
> 
> Accoustically is there any advantage in putting a non-perf screen on a false wall so that linacoustic can be placed on the entire real wall behind it vs putting the screen on the real wall with just linacoustic on the wall around it?



Not under ordinary circumstances, Mike. Special circumstances would include:


Fixing a low-frequency 1/4 wavelength cancellation dip from the front wall. This would typically require a few inches thickness of absorption to be effective at low frequencies.


Deadening early reflections from bi/di-polar or omnidirectional front speakers.


- Terry


----------



## dennisgg




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> This has been discussed before. In short - nobody here or anywhere else I hang out has been able to explain how that would even remotely work. The ONLY thing it MIGHT do is to act as a difffusor - but the diameter isn't large enough to work below maybe 100-150Hz or so.
> 
> 
> Somehow, someway, a bass absorber has to absorb bass. It can be thick porous material that turns the waves into heat, it can be a tuned absorber where either an air column or a tuned membrane vibrate at specific frequencies and are damped, or it can be an active system wher the inverse of certain waves is generated out of phase to cancel certain frequencies. It can even be hanging panels that literally move when the waves hit them thereby sucking energy from the wave.
> 
> 
> The sand filled tube cannot do any of these things. It won't pass a wave, it has no way to vibrate due to being damped with sand, it can't move due to its mass, and has no air column (damped or not) that can be tuned.
> 
> 
> Look for another solution.




Thank you for your response. I am sorry if it was addressed before - this thread is huge and I read the first 3-4 pages, but haven't had time for the rest of it (working too many hours). I will look into another alternative. Thank you for the quick and informative response.





Dennis


----------



## mmmkam

Thanks for the feedback Terry!


----------



## Tweakophyte




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> If you cut the sheet in half so you have 2 pcs that are 2x2, then cut those ONCE on the diagonal, you end up with 2 triangles that are 2'x2'x2.8' from each of the 2 pieces for a total of 4.
> 
> 
> If you cut the same sheet in half and then cut each of those 2'x2' piecs with an 'X' pattern, you get 4 triangles that are 1.4'x1.4'x2' from each of the 2 pieces for a total of 8.
> 
> 
> Either way works, just a matter of how big you want the face of the absorber to be and how much wall space you have.



Doh... Bad math again on my part. I need to wake up before I type some days. (Thanks Ford, too)


I've read about these wedge traps and just assumed you were going for the 2' SIDES instead of the 2' face. I think there was an article these... If I find it I'll link it (and if someone else has it, go ahead an post it).


It still begs the question... for that given volume of rigid fiberglass (three 2'x4'x2") which configuration makes a better bass trap? We can make a 4' tall wedge with a 2' face and continuous thickness to the wall, or a 4' tall, 6" thick panel with a 2' face and variable spacing from the wall.


... and then I will try to stop with the questions...


----------



## trystan

Can anyone comment on this product, vs the fibergalss boards..are they really the same ?

Can the boards be put up without covering them ?



Owens Corning Select Sound Black Acoustic Board


Thanks


----------



## bpape

Tweak,


It's kind of apples and oranges. When you make 1 16 Sq Ft and 1 8 Sq Ft, you're changing everything. The 4' tall one will absorb deeper but you'll only have half the surface area of bass absorbtion in the room. If you're limited to an either/or situation, I'd go with 4" of fiberglass floor to ceiling since that will also address all of the tri-corners instead of just half of them - and you'll have more surface area in general. The solid thickness is really only helping in the deep bass over 4" straddling a corner.


Dennis - sorry if I came across wrong. No problem repeating the information. When you see something like that from professionals it does make you wonder. I can't see how it would work. I've asked several people who are acoustics pros and none of them thought it would work either.


----------



## BasementBob

Tweakophyte:

Studiotips Corner Absorber 
Studiotips Corner Chunk 



> Quote:
> for that given volume of rigid fiberglass (three 2'x4'x2") which configuration makes a better bass trap? We can make a 4' tall wedge with a 2' face and continuous thickness to the wall, or a 4' tall, 6" thick panel with a 2' face and variable spacing from the wall.



If three 2'x4'x2" panels are all the materials you have to build with, I suspect you'll be happier with three Studiotips Corner Absorbers that are 2" thick, 4' tall diagonals with a 2' face. That would give a little less bass absorbtion in the low frequencies per surface ft^2, but probably more sabins of absorbtion in all frequencies including bass for the room.


----------



## Megalith

Quick bass traps question:


I've got a room that only has one traditional corner where regular bass traps would fit...the rest are tougher since the ceiling is actually angled upwards.


How effective would regular bass traps be in angled corners. If I were to put one in, they'd only be touching the side walls, with the ceiling part open.


----------



## bpape

Try them in the horizontal corners from side wall to side wall.


----------



## fisherman

I've read every post on this thread (whew, what a brain spinner) and It didn't seem to answer a fundamental wall treatment type - sheet rock. I've read complaints that it has to be used. Is it the best covering, particulary inside where resonance not isolation is the concern. What is the best covering to attach to the wall studs?


----------



## LarryChanin




> Quote:
> Originally Posted by *fisherman* /forum/post/0
> 
> 
> I've read every post on this thread (whew, what a brain spinner) and It didn't seem to answer a fundamental wall treatment type - sheet rock. I've read complaints that it has to be used. Is it the best covering, particulary inside where resonance not isolation is the concern. What is the best covering to attach to the wall studs?



Hi,


By discounting sound isolation you may have inadvertently clouded the issue. Even if you are not concerned about sound getting out of your theater, if you are truly concerned about acoustics then you must logically address sound getting into the theater.


This ultimately gets back to your question of "best". What do you mean by "best"? Many home theater builders are correctly concerned about BOTH the absorption of the walls and their sound isolation properties. Therefore in terms of economics, and reasonably balancing both concerns, starting with drywall walls and treating them (any number of ways) does represent a pretty good alternative to walls constructed of other materials.


For purposes of illustration suppose we follow this reasoning about ignoring isolation to an absurd degree. In such a case we don't need solid walls at all. In such an extreme case we could substitute the appropriate type of fabric walls, and poof, the resonance problems would be solved.










Larry


----------



## BasementBob

I think of 'best' as good sounding HT room.


'best for individual' involves

a) budget

b) concerns (how close is that noisy furnace!. I don't care if it sounds nice I just want to hear what they say!)

c) local(able) materials.


For materials it's just a question of knowing what they do, and applying them to solve (b) given (a).


Everything (products [gypsum, wood, steel, mineral wool] and systems [walls, rooms, couch]) : transmits, absorbs, and reflects sound to different degrees.


A room is a big system, with lots of these parts.

The pursuit of 'best' room, means using these parts in a combination that results in the best room, givin (a)/(b)/(c).


sheetrock - has mass, and tends to reflect a lot. One layer drywall and no insulation on a flexable wall (G13_WS90(610)_G13) might be soundproof to STC-30 with 20dB TL at 50hz -- and thus let a fair bit of 50hz noise out of the room making it a reasonably effective (higher sabins per ft^2 - it's still an inefficient and uneven and unpredictable absorber as absorbers go but you tend to have A LOT of ft^2 of it) bass centric absorber. Same materials, but combined as a double stud wall, with two layers of drywall and green glue (G16_GG_G16_WS90(610)_GFB90_AIR25_WS90(610)_GFB90_G16_GG_G16 ), might be soundproof to STC-71 with 30dB TL at 50hz -- this wall reflects a lot more of the sound back into the room (real lousy absorber because it's WAY innefficient at absorbtion).


fiberglass, rockwool, acoustic cotton, decent foam, polyester: much better at absorbtion than drywall. Leaps and bounds better at absorbtion than drywall. Placement affects its absorbtion rate at various frequencies (diagonal corner placement boosts LF absorbtion a lot extending its broadband absorbtion)


Too much HF absorbtion in the room and you want more LF absorbtion -- cover what you've got:

a) 100micrometer PVC foil - reflects HF, lets LF through it.

b) slats

c) membrane or helmholtz


Have an annoying reflection producing comb filtering or imaging problems, but you already have too much absorbtion at all frequencies -- consider diffusion to scatter/reduce one of the reflections. Sound reflecting off something causing a problem, how about a twist poly. The walls themselves are good reflectors, as are cabinets. Cabinets can block a reflection - or move it a bit.


You want speach inteligibility (low background noise, few early reflections, masking, FR, distortion, time), and ambiance and spaciousness -- these are a blancing act -- that combine everything the room is made of, from the walls, to the carpet, to the couch, and everything else.


A friend of mine bought a HomeTheatre-In-A-Box with 10" LCD screen for his 8 year old son. Who promptly took it into his bedroom where he has built (leaned and tied with rope) a few 4'x4' sheets of plywood into a sort of 'fort' in the corner of the room. Set the HTIB up inside the 'fort' and watched Bambi. He bragged about it to all his friends. "It's just the best!" The 8 year old had (a) no budget, (b) extremely good hearing, and (c) local is defined as what's under the christmas tree and what's in the garage. I understand the neighbour's 'fort' occupant is jelous.


----------



## fisherman

I see how I left the interpretation I was discounting isolation. To clarify, I have found lots of information on isolation. For my DIY theater in progress I'll be using QRock 545 THX with RSIC-1. Also, by best I mean what the major knowledgeable AVS members would say about: 'this is the way to go about no bad seat in a HT'.


What is not clear is reflected in the points made by both and BasementBob and LarryChanin "Everything (products [gypsum, wood, steel, mineral wool] and systems [walls, rooms, couch]): transmits, absorbs, and reflects sound to different degrees" and LarryChanin For purposes of illustration suppose we follow this reasoning about ignoring isolation to an absurd degree. In such a case we don't need solid walls at all. In such an extreme case we could substitute the appropriate type of fabric walls, and poof, the resonance problems would be solved Why do we need drywall (besides cheap and available).


It seems by trying to understand all members' advice; you all have a best practice' in mind. What is that best practice for inside covering once you have isolation - no sound in, no sound out - accomplished


You're needed for you for you mind not you're


----------



## jandawil

Hey everyone....I found a dealer close by that exclusively deals in Roxul mineral wool and their prices are very good. I am planning on doing corner bass traps in the rear 2 corners of my HT and will cut 4" thick wool into triangles with a 2' face and they will go 12" deep into the corners. If my math is correct I can get 8 triangles out of a 24'X 48" sheet and at 4" thickness one sheet will get me 2' high. Their price is about $19.00 for 24 sq feet (4 24"X48" sheets) so that will give me 8' high corner traps for less than $20 each!!! That sounds very reasonable. I often hear of people spending far more than that. Am I missing something??


Also since they do not carry rigid fiberglass, I am limited to 1 1/2" mineral wool for sound panels for my early reflection points on the side walls. Has anyone used this for that purpose?? Is it rigid enough to simply cover in a fabric and hang it on a wall?? Will I need some sort of backing or frame to support it?? Any experience out there would be greatly appreciated.


Thanks a bunch.....


----------



## bpape

Jon,


Yes. You can get 8 1.4 x 1.4 x 2' triangles from a single 2'x4' piece. Each piece being 4" thick will yield 32" vertical inches of solid triangle from a single sheet. So from 24 Sq Ft, you can get 96" vertically or 8'. For clarity, 24 Sq Ft is 3 sheets, not 4 - each is 8 sq ft. Just make sure of the density of the material. That's a very good price if it's 8lb/cu ft.


As for the refleciton panels, if you can get a lighter density - like around 3-4 lb/cu ft. If it's all 8lb, I'd look at something different as those are too dense IMO.


----------



## jandawil




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Jon,
> 
> 
> Yes. You can get 8 1.4 x 1.4 x 2' triangles from a single 2'x4' piece. Each piece being 4" thick will yield 32" vertical inches of solid triangle from a single sheet. So from 24 Sq Ft, you can get 96" vertically or 8'. For clarity, 24 Sq Ft is 3 sheets, not 4 - each is 8 sq ft. Just make sure of the density of the material. That's a very good price if it's 8lb/cu ft.
> 
> 
> As for the refleciton panels, if you can get a lighter density - like around 3-4 lb/cu ft. If it's all 8lb, I'd look at something different as those are too dense IMO.



Thanks bpape...the density is 4.5 lb BTW. The co-effecients are 1.03 at 125 Hz for the 4" thickness. Will this work for bass trapping for what I am planning to do??? Can it be compressed by cramming it in there???


----------



## mccabem

Just jumping in here with a question relating to putting carpet on the walls. From what I've read on this thread, I obviously need to put absortion material below ear level. Most likely I'll just go the entire length of the room or at least the distance from screen wall to seating instead of trying to figure out the point of reflections and putting absorbing panels at that point.


My question is with the upper portion of the wall. Can I cover the sheetrock with a real tight woven carpet? I want to do this so I don't have to build a lot of frames and cover with GOM and I don't really have the sheetrock finishing skills to just paint it either?


Any good or bad characteristics of carpeting the upper half of my side walls?


If this has been previously addressed elsewhere, please direct me to that thread.


Thanks,

Matt


----------



## myfipie




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> Just jumping in here with a question relating to putting carpet on the walls. From what I've read on this thread, I obviously need to put absortion material below ear level. Most likely I'll just go the entire length of the room or at least the distance from screen wall to seating instead of trying to figure out the point of reflections and putting absorbing panels at that point.
> 
> 
> My question is with the upper portion of the wall. Can I cover the sheetrock with a real tight woven carpet? I want to do this so I don't have to build a lot of frames and cover with GOM and I don't really have the sheetrock finishing skills to just paint it either?
> 
> 
> Any good or bad characteristics of carpeting the upper half of my side walls?
> 
> 
> If this has been previously addressed elsewhere, please direct me to that thread.
> 
> 
> Thanks,
> 
> Matt



You do not want to put carpet on the walls.. It is only going to help with the high end and leave the low end bouncing around the room.. The low end is the biggest problem areas in rooms. Stick with rigid fiberglass panels on first reflections and bass traps in the corners... Bass traps should be 4" thick and first reflection panels should be 2 " thick..


Glenn


----------



## bpape

Jon.


The 4.5lb will work. If you want it a bit better at lower frequencies, you can use 6" to compensate somewhat for the lower density.


----------



## mccabem

Glenn,


Thanks for your reply. To clarify, is the carpet going to absorb too much of the mids/highs and cause the room to sound dead?


I plan to use the fiberglass insulation below ear level and just have concerns with the material above the ear, no carpet below ear leve.


Thanks,

Matt


----------



## myfipie




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> Glenn,
> 
> 
> Thanks for your reply. To clarify, is the carpet going to absorb too much of the mids/highs and cause the room to sound dead?
> 
> 
> I plan to use the fiberglass insulation below ear level and just have concerns with the material above the ear, no carpet below ear leve.
> 
> 
> Thanks,
> 
> Matt



Sounds like to me you are going to have way to much HF absorption.. I am not going to say it will go dead, because of type of carpet and so on, but carpet is really not recommend for acoustic treatment.. For the upper wall it would be best to straddle 4" panels in the corner where the wall meets the ceiling.. That will act as a bass trap..


Glenn


----------



## Tweakophyte

...just thought I would lay this out in case I had confused anyone.



> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Tweakophyte:
> 
> Studiotips Corner Absorber
> Studiotips Corner Chunk
> 
> 
> If three 2'x4'x2" panels are all the materials you have to build with, I suspect you'll be happier with three Studiotips Corner Absorbers that are 2" thick, 4' tall diagonals with a 2' face. That would give a little less bass absorbtion in the low frequencies per surface ft^2, but probably more sabins of absorbtion in all frequencies including bass for the room.



Thanks (again) for the links. I can clarify what I was trying to describe for my options. This is what I said


> Quote:
> Is it better to have two 6" thick 4' tall panels straddling the rear corners, or one 4' tall wedge trap in only one corner.


 Studiotips Corner Absorber is what I am describing when I said "a 4' tall, 6" thick panel with a 2' face and variable spacing from the wall " and "two 6" thick 4' tall panels straddling the rear corners" In this case the Studiotips corner absorber is suggesting at least 4" thick (I am looking at 6"). They also suggest adding some additional fiberglass behind the panel that is straddling the wall, by tucking in an additional piece of OC703 into the corner itself.

Studiotips Corner Chunk is what I meant when I said "wedge trap". There are two cutting patterns: one for a 24" face (8 wedges per piece of rigid fiberglass) and one for a 34" face (4 wedges per piece of rigid fiberglass).


Unfortunately the only measured the 4" thick "corner absorber" compared to a 34" face "corner chunk" aka "Super Chunk". Neither are the options I am considering since I am looking at a 6" thick "corner absorber" (with a 24" face) compared to a 24" faced "corner chunk". The comparison would be neat because they use the same amount of material.


My current thought is to make a corner absorber, 4-6" thick for ease of construction and portability if the WAF becomes a factor. If I want to improve the performance of that, in the future I can add "fluffy" insulation, or other material behind the corner absorber to improve the bass trapping performance.


Thanks again.


----------



## stef2

Hi everyone. I've been following this thread for a while and a few details about sound treatment remain unclear to me. Would anyone be kind enough to enlighten me?



1- I am about to finish drywalling my home theater and I still have the possibility to change the dimensions of my room when I'll build a faux wall for my screen. My room's dimensions would be 141 inches wide by 93 inches high by 242 inches long. This is close to a 1:1,5:2,5 ratio. Is this a good room size ratio? The dimension that I could modify is the lenght. Any suggestions?



2 - My second question is about corner bass traps. Considering a constant dimension and using the same materials, is it better to completely fill the corner or to leave an air gap behind the fiberglass panels ? (My corner traps would be triangular with a diagonal of 2 feet and I plan to use OC703 for those)



3 - And at last...Centered in the wall behind my (non perforated) screen there is a recess about the three feet wide and two feet deep that goes from the floor to the ceiling. It was intended for a fireplace and its chimney. What should I do with this? I thought about filling it with insulation and leaving it in contact with the room using GOM. But since this "shape" is directly behind the screen, should I just make it disappear by running drywall in front of it, making the front screenwall completely linear? If so I would probably also fill the cavity to avoid creating a Huge drum...



Thanks in advance for your precious feedback!


----------



## Ethan Winer

Stef,


> This is close to a 1:1,5:2,5 ratio. Is this a good room size ratio? 
is it better to completely fill the corner 
It was intended for a fireplace and its chimney. What should I do with this?


----------



## Ready2Buy

Hi all,


I just discovered this thread and let me say that I am very impressed with the quality of the content and the many excellent contributions made by the acoustics experts here. It is really a joy to come across this jem.


I too am one of those with limited DIY skills and limited budget who is trying to transform an EXISTING room in our home to a home theater. (Yes I too got infected by the bug.) Already bought the 7.1 speakers (actually the ".1" has not been bought yet), the receiver/amp, the DVD player and the Radioshack digital SPL meter. The new objective is to improve the room acoustics with the simplest possible design and the least amount of labor.


With that said I have to second BasementBob's view that one of the most important issues facing the DIYer is the availability of materials in his local area. For example, I live in Los Angeles and after already calling eight different insulation suppliers in my area I found that none of them has the 4 thick fiberglass boards for sale. Some of them don't even carry any fiberglass rigid board insulation at all. BTW, if anybody in this forum knows where to get 4 thick boards anywhere near Los Angeles please tell me. I am willing to drive up to 100 miles from downtown.


The best I was able to locate in my area are 2 thick boards:


(1) JM-IS300: Cost $79 for nine 2x2x4 boards per bundle ($1.10 per sq.ft.)

(2) JM-814: Cost $122 for only six 2x2x4 boards per bundle ($2.54 per sq.ft.)

(3) OC-703: Cost $76 for ten 2x2x4 boards per bundle ($0.95 per sq.ft.)


The absorption coefficients (from bobgolds.com) for 2 JM-IS300 and 2 JM-814 are identical and both are a little better at low frequency than the 2 unfaced OC-703. Obviously the best deal is the OC-703 if cost per unit is the only factor. However, considering that the above three suppliers are 15 miles 35 miles and 75 miles away from my house it appears that the JM-IS300 is my best option.


So I have two questions for the bass trap experts and those who have already done a fair amount of thinking on this subject.


First is the JM-IS300 2-thick a good material to build bass traps? Or should I continue to look for other materials or thickness?


Second, I have come up with a simple design to make these and would like to invite comments from this forum. In fact this design is so simple that I am even embarrassed to describe it. It doesn't require any cutting of the fiberglass (we know this material is unpleasant to work with) and it doesn't require that I build a frame of any kind. What it does require is a lot of panels. Here it is:


At each of the 4 corners in the room I will use twenty-four 2x2'x4' panels as follows. Stack 12 2x2'x4 panels together creating a 2'x2'x4' solid shape. Wrap it like a Christmas gift using speaker fabric (Joann's fabrics has it for $6/yard) and then stand it up in the corner. Build another one just like the first one and stand up on top of the first one. This is now a 2'x2'x8' square pillar placed against the walls into the corner of the room. Repeat this process three more times to block all four of the room's corners and you are done. These square pillars are free-standing and do not require a frame. To pull this off in all four corners I will need a total of 4x24=96 2x2'x4' boards. This will cost me about $850 for the fiberglass alone but should work great! This design should be even more effective than the prismatic Superchunks design Bob mentioned with the 34 exposed face as my square pillars will have an even larger 48 (2 faces of 24 each) exposed into the sound field of the room.


Please comment on the effectiveness of this extremely simple design. Of course I would rather have the 4 thick boards so that I spend a bit less for fiberglass but I can't find any at the moment. Yes I know that I am using too much fiber but the simplicity of the design outweighs having to get cute with the framing and the wrapping issues.


Thanks again to everyone contributing to this thread. It's a real asset for those of us who are DIY-challenged and have a limited budget that doesn't allow for purchasing the good stuff (i.e., realtraps, megalenrds, tubetraps etc.) but still want to reach deep down and damp those low frequency acoustic waves.


John


----------



## Terry Montlick

Design looks good, John. JM-IS300 is just as good as any other fiberglass. You can ignore small differenced in published absorption coefficients of fiberglass, particularly at low frequencies. It is just measurement error. Just go by the density, and all of these are 3 pcf.



> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> It's a real asset for those of us who are DIY-challenged and have a limited budget that doesn't allow for purchasing the good stuff (i.e., realtraps, megalenrds, tubetraps etc.) but still want to reach deep down and damp those low frequency acoustic waves.



You are building the good stuff!! There is no difference between acoustical treatments bought ready-made with cash or with sweat equity.


- Terry


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> You are building the good stuff!! There is no difference between acoustical treatments bought ready-made with cash or with sweat equity.
> 
> 
> - Terry



I appreciate this Terry. The only other question I have on these materials has to do with the health risk issue (if there is one). I see a number of posts that mention that fiberglass materials either cause cancer or that they are generally unhealthy to be around. I have also seen an equal number of posts disputing these claims. I understand that we have to wrap these panels possibly twice with polyester batting and then again with a nicer looking breathable fabric. But is this enough for these panels to not interfere with our health? I mean do we know of anybody who got sick or developed respiratory problems from having too many panels in his room?


Also do we know how the different fiberglass brands compare on the health issue? Is for example the JM-IS300 material "healthier" to have inside your room than the OC-703 material? Or are they all pretty much the same health-wise?


John


----------



## JamesE




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> At each of the 4 corners in the room I will use twenty-four 2x2'x4' panels as follows. Stack 12 2x2'x4 panels together creating a 2'x2'x4' solid shape. Wrap it like a Christmas gift using speaker fabric (Joann's fabrics has it for $6/yard) and then stand it up in the corner. Build another one just like the first one and stand up on top of the first one. This is now a 2'x2'x8' square pillar placed against the walls into the corner of the room. Repeat this process three more times to block all four of the room's corners and you are done. These square pillars are free-standing and do not require a frame. To pull this off in all four corners I will need a total of 4x24=96 2x2'x4' boards. This will cost me about $850 for the fiberglass alone but should work great! This design should be even more effective than the prismatic Superchunks design Bob mentioned with the 34 exposed face as my square pillars will have an even larger 48 (2 faces of 24 each) exposed into the sound field of the room.
> 
> 
> John



This is a brilliant idea. Fill the blocks with regular fiberglass insulation for added low end absorbtion and buy yourself "The Master Handbook of Acoustics" to fill in the gaps of information on this forum. Although, this forum is pretty hard to beat.


----------



## Tweakophyte

John-


I don't know if you saw that I took 5 peices of JM-814 that were in a bag and stuck them in one corner for a quick a/b. I experience a HUGE difference in frequency response. I played a techno tune that has a lot of long, reverse, bass sweeps. This normally exposes all the ups and downs of the FR. The simple bag in the room trick was instant validation.


Some will tell you to take a few unwrapped bales of R30 and stick them in a corner... not as clean as the mega-pillar approach.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> I appreciate this Terry. The only other question I have on these materials has to do with the health risk issue (if there is one). I see a number of posts that mention that fiberglass materials either cause cancer or that they are generally unhealthy to be around. I have also seen an equal number of posts disputing these claims. I understand that we have to wrap these panels possibly twice with polyester batting and then again with a nicer looking breathable fabric. But is this enough for these panels to not interfere with our health? I mean do we know of anybody who got sick or developed respiratory problems from having too many panels in his room?
> 
> 
> Also do we know how the different fiberglass brands compare on the health issue? Is for example the JM-IS300 material "healthier" to have inside your room than the OC-703 material? Or are they all pretty much the same health-wise?
> 
> 
> John



The fibers are contained by the fabric. They do not float in the air to be breathed. Future research may turn up health risks for people (nothing so far), but I believe that any such risk would be confined to installation, and dealt with by wearing a dust mask.


- Terry


----------



## Ready2Buy




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> John-
> 
> 
> I don't know if you saw that I took 5 peices of JM-814 that were in a bag and stuck them in one corner for a quick a/b. I experience a HUGE difference in frequency response. I played a techno tune that has a lot of long, reverse, bass sweeps. This normally exposes all the ups and downs of the FR. The simple bag in the room trick was instant validation.



Did you just stand them up into the corner in the shape of a box 4' high trapped between the 2 walls of a corner? At 2" thick and using 5 boards you have built a 10"x2'x4' solid rectangular absorber. I am surprised that you notice such a big difference in your music with only 5 panels of material and in only one corner of your room.


Have anybody done a study in how to best place these panels in a room? I mean given a a specific number of panels (say 96 2"-thick panels) would you stack 24 in each of the 4 corners and be done? Or would you try to maximize exposed area by sacrificing the thickness of the material in the 4 corners of the room?


What would help greatly here is an acoustic model of an empty room with the ability to add rectangular absorption panels all around the corners and predict the resulting sound field. The user would enter the dimensions of his room and proceed to place 2'x4' panels at various locations (that only he knows is allowable) until the right number and the right placement emerges that satisfies his sound requirements. Obviously I am dreaming here but hey why not? This would definitely be worth a "sticky"


----------



## Kal Rubinson

Take a look at CARA 2.1. You can put almost anything in to the model.
http://www.rhintek.com/cara/cara21desc.php 


Kal


----------



## Ready2Buy

I am now the proud owner of 63 JM-IS300 2" 2x4 boards. All for $500 and I cleaned out the guy's stock!


I was speaking to another fellow on the net about making these 2'x2'x8' square pillars and he suggested that I don't lean them against the corners because the velocity of the acoustic waves on the wall is zero and they wouldn't be very effective. He instead suggested that I space them 6" away from both walls to gain even more effectiveness down low.


If I were to do that I would probably have to make a rectangular frame for them to gain more stability to stand up straight and then attach the fabric to the wood frame instead of gluing it directly on the panels. It's a bit more effort to build it but because its a simple square frame I think I can give it a try.


My question is, does spacing a 2'x2'x8' fiberglass tower 6" away from both corner walls really gain you anything as compared to having it resting directly on the walls? (My room is 20'x20'x8' and has a pair of modes at 28 Hz and then again at 56 Hz.)


John


----------



## bpape

You'd be just as well off to make them 6" thick and put them up straddling the vertical room corners at 45 degrees. That gives you MORE distance from the boundary and gives you extra thickness for even better control down low. Doing all 4 corners this way will still cover 1.4'x8' on each of the wall surfaces and only use up 24 of the 2" panels.


Bryan


----------



## Ready2Buy




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> You'd be just as well off to make them 6" thick and put them up straddling the vertical room corners at 45 degrees. That gives you MORE distance from the boundary and gives you extra thickness for even better control down low. Doing all 4 corners this way will still cover 1.4'x8' on each of the wall surfaces and only use up 24 of the 2" panels.
> 
> 
> Bryan



Hmmm, thanks for the reply. I read somewhere in an Ethan Winer article that you need to "trap" a quarter of the wavelength of sound for maximum absorption but even if you trap 1/8 of the wavelength will also give good results. I got modes down at 28 Hz whose wavelength is 40 feet long so to trap even 1/8 of that I would need 5-foot thick panels. I am using 2' panels wich means I am trapping a mere 1/20 wavelength at this frequency which is probably not enough. Why would a mere 6" spaced off the wall work just as good as 2'-thick bricks? At a frequency of 28 Hz? I am confused ...


John


----------



## Brock225

First of many questions to come. In making diagonal bass traps for corners, should the surface facing the room have a paper, vinyl or foil facing on it under the fabric to allow low frequency and not higher frequency sound waves to be absorbed.

I have subs in the back 2 corners of the room. Do I ignore any bass trap of any kind at the back of the room?


Brad


----------



## Glenn Baumann

Brad,


I believe the conventional wisdom is that all corners are valid and effective. Treatment is also very effective at not only the wall-wall corners as in your case but at the wall-ceilng and wall-floor junctures as well. I have also read that the juncture where two walls and the ceiling corner meets is another very effective absorption spot, this being the tri-corner.











...Glenn


----------



## Stima

First, let me THANK YOU for reading this long post and helping me out. You will receive many rewards in heaven for your good deeds!!










As it seems with many others I have reached the Acoustical Treatment phase so I turn to the experts here for opinions.

*Background:*

Room is essentially rectangular (11' wide x 16' long x 8' high (height varies over rear riser and front mini-stage).


Seating is at 11' and 14'. (Riser is 10" high)


Whats odd about my room is the front has a "half-hexagon" extension for a bay window above.


I plan to put an acoustically transparent screen and wall at the beginning of this hexagon extension to visually square off the room. Speakers will be mounted behind the wall. The room has a thick berber carpet, and I don't have any plans to treat the ceiling with AT. (I will treat the undersides of the lighting softis however with 703).


I am not extremely worried about bass leaving the theater. However, I did build separate floating walls and a ceiling. I decided to only do a single layer of Drywall rather than "beef" them up with GG and a second layer. I did this to allow the walls\\ceiling to absorb bass rather then reflect it into the room. Also, I filled the void between the two walls and ceiling\\floor with fiberglass.

*More Background:*

Went and visited Dennis E.'s 2.35:1 theater for advice and he suggested I do the following:
Put 703 from floor to ceiling on the "extension walls" all the way to the first listening position.
Cover approximately half the remaining walls with 703.
Cut faux AC vents into my riser and shove batting into the cavities to utilize it as a base trap.
Tear down the drywall from my front wall (now acoustically transparent) and go with a 2.35:1 setup placing all speakers behind the AT screen\\wall.

*Questions:*

1.) My riser is formed by 12 square areas approximately 16"x 24". How many (if any) of these areas should I make into bass traps?

2.) Should I utilize the large area behind the screen for bass trapping since it will be hidden and won't affect the cosmetics of the room?

3.) Putting 703 from floor to ear height is an approximation mainly for amount of 703, not position. Therefore, I can put panels in the "middle" of the remaining walls surrounded by batting. Correct?

4.) Finally, was my thought process with the single layered walls\\ceiling completely inaccurate? I only ask this because I still have the opportunity to put a second layer on the walls before I put acoustical treatments up. (A second layer on the ceiling would be very difficult now given lighting and painting is completed.) More pertenant: Is there even any reason to add this second layer to the walls since the ceiling is single layered?


Hope that wasn't to many questions.


I REALLY do appreciate any help and will carefully consider any suggestions. (I already am tearing down the permanent wall I _*WAS*_ going to use to "visually square" off the room per Dennis's suggestion.)


Thanks,

Dan


----------



## BasementBob

Ready2Buy:



> Quote:
> the velocity of the acoustic waves on the wall is zero



That's not quite true.


Sound going straight towards a wall, will have it's velocity drop to zero and pressure go up at the wall surface.

See "Reflection of a sound wave at a hard wall"

at http://www.isvr.soton.ac.uk/SPCG/Tut...ter-reflex.htm 


Think of a swiming pool. Make a splash (wave) on the surface, and the wave goes towards the wall, goes up the wall (stops velocity at the wall as the wall changes the wave from horizontal velocity to vertical potential energy), reflects, and returns.


But sound going along the wall (parallel to it), doesn't convert velocity to pressure -- it stays as velocity.


Think of a river, or a water pipe, certainly water flows along the 'walls'.

Think of a swimming pool, you've seen waves traveling along walls of a swimming pool (both parallel and at angles).


----------



## Tweakophyte

Bob-


Great clarification. I guess it's more common than not that the sound "splashes" versus bounces straight back (which would cause it to go to zero). This also highlights why tri-corners are a great place to focus.


----------



## Ready2Buy




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Ready2Buy:
> 
> 
> That's not quite true.
> 
> 
> Sound going straight towards a wall, will have it's velocity drop to zero and pressure go up at the wall



Hi Bob,


I think I understand the swimming pool analogy but it still doesn't explain to me why people get more damping out of their panels when they space them several inches away from the wall versus placing them directly against the wall. Reading these forums there are countless statements from experts pointing out that large airgaps between the panels and walls somehow increase the absorption of sound while using the same amount of fiberglass material. And they have measurements to prove this. The only explanation I was able to glean from what I read had to do with the wave velocity being zero at the wall.


But why would a 6"x24"x96" fiberglass panel placed diagonally in the corner of the room give about the same performance as a 24"x24"x96" fiberglass brick placed in the corner? Bpape's opinion is that you will probably get about the same damping out of both even if you spaced the 24"x24"x96" brick 6" out from the corner. I am trying to understand why this would be right because it stands against the basics physics of sound I thought I knew. If he is right, then there must be some fundamental limit of absorption that, once we reach it, adding more fiberglass will not bring more dividends. Is this what it is?


(My room is pretty square 20'x20'x8' without any openings and I've got double modes at 28 and 56 Hz. That's why I went out amd bought all these fiberglass boards. I thought the more boards the better. )


John


----------



## bpape

John,


OPTIMAL is to get the wave at a quarter wavelength from the wall. This does not mean that you can't be effetive at other places. This does however explain why spacing panels off the wall helps - you're getting closer to longer waves' 1/4 length spacing from the wall.


There are several things that control how deep an absorber will reach effectively.

- Thickness (more of the wave in absorbtion at any time and more absorbtion to slow things down in general)

- Density (slow down larger waves more per inch of thickness)

- Distance from the wall - see above.


You have a lot of stock to work with - use it wisely. As I said previously, make the absorbers 6" thick. This gets the leading edge of the absorbtion farther from the wall (see #3 above) and also give you more thickness for the same density material (see #1 above).


Adding more SURFACE AREA will still increase absorbtion. The problem is that you can get to a point where OTHER frequencies are now too damped. The idea is to bring the decay time in the room down to an even balance across the whole spectrum. Some things in the room are already doing absorbing.

-air

-carpet

-people

-furniture

-drywall walls


The trick is to know what they've all done so far and then see where you stand in relation to the target time for your particular room size and usage.


----------



## Ready2Buy




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> John,
> 
> 
> OPTIMAL is to get the wave at a quarter wavelength from the wall. This does not mean that you can't be effetive at other places. This does however explain why spacing panels off the wall helps - you're getting closer to longer waves' 1/4 length spacing from the wall.
> 
> 
> There are several things that control how deep an absorber will reach effectively.
> 
> - Thickness (more of the wave in absorbtion at any time and more absorbtion to slow things down in general)
> 
> - Density (slow down larger waves more per inch of thickness)
> 
> - Distance from the wall - see above.
> 
> 
> You have a lot of stock to work with - use it wisely. As I said previously, make the absorbers 6" thick. This gets the leading edge of the absorbtion farther from the wall (see #3 above) and also give you more thickness for the same density material (see #1 above).
> 
> 
> Adding more SURFACE AREA will still increase absorbtion. The problem is that you can get to a point where OTHER frequencies are now too damped. The idea is to bring the decay time in the room down to an even balance across the whole spectrum. Some things in the room are already doing absorbing.
> 
> -air
> 
> -carpet
> 
> -people
> 
> -furniture
> 
> -drywall walls
> 
> 
> The trick is to know what they've all done so far and then see where you stand in relation to the target time for your particular room size and usage.




I am with you. So to summarize, the three keys to building good bass traps using fiberglass are


1. Panel Thickness

2. Panel Density

3. Spacing from wall


With regards to the first key point, I have now bought so much fiberglass material that I can make pretty much any thickness from 2" all the way to 24". I think everyone seems to agree that the thicker we make'em the better the result. (Does anyone disagree on this point?)


With reqard to panel density, I am pretty much stuck with the 3 pounds-per-cubic-foot matrial due to local availability (JM-IS300).


The third key point however, is the most difficult to interprete because it addressses the PLACEMENT issue. The best placement requires that we accept a larger reduction in our usefull room space and placing the traps really far from the walls.


In my case, I am under the constraint of not wanting to dedicate more than 6 square feet per corner trap (or 24 square feet for four) from the 400 square feet available in this 20'x20' room. (That's about 6% of the total area of the room going to the corner treatments). If I were to go with traps that straddle the corners diagonally as you suggest I would at least use 10" thick ones (using five 2"-thick panels one behind the other). These traps would still fall inside a 24"x24" corner envelope wasting about 4 square feet of space per corner (16 sq. ft. total) of my room. To pull this off I would have to use a total of 40 panels for all four corners which would leave me with the remaining 23 panels to treat first reflections. Hmmm, I may have bought too many










The problem you mentioned about overdoing it by absorbing too much of the mid and high frequencies has me worried however. I bought this many panels because I though I was going to use most in the corners and was going by what Ethan said in a previous correspondence, i.e., "you can't have too many bass traps".


(At first I thought this was not too hard to figure out, now I am not so sure ...)


----------



## myfipie

If you put some FRK on your bass trap panels you would be fine.. That should keep the room alive... Not making it dead but absorbing the low end.. But for the first reflections you should not use the FRK... I can't see needing 23 panels for first reflection points..


Glenn


----------



## Brock225

On first reflections using a mirror would the following affect dampening material on side walls. My main L&R are toed in approx. 18 degrees, 9 ft. apart and 15 ft in front of me. Do I need to make any adjustment for the fact that (this is an assumption I am making) the sound waves would hit closer to me on the side wall even though I see the speaker in the mirror? I see more of the side of the speaker than if it was facing straight forward. Is this nothing to be concerned about or does it depend on the disperion pattern of the Martin Logan SL3's.


----------



## Stima

Anyone have opinions on my few questions?


----------



## ebr

Stima - I'm afraid you are getting into some things that are very specific to your room so the answers to your questions are going to be "it depends..."


You have to realize most of the true experts who contribute out here solve the very detailed problems you are asking about for (at least some part) of their living. So, it may be very difficult to get complete answers to your questions in this forum. If you really want to be sure you do this right, I would suggest contacting one of these guys and talking to them about providing you with specific service.


Now, that being said - someone like Bryan or Terry or Ethan may jump in here and help you out at least to some extent. I am continually amazed at the amount of time, effort, and advice these guys lay out here for free.


----------



## Ready2Buy




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> If you put some FRK on your bass trap panels you would be fine.. That should keep the room alive... Not making it dead but absorbing the low end.. But for the first reflections you should not use the FRK... I can't see needing 23 panels for first reflection points..
> 
> 
> Glenn



Hi Glenn,


Instead of FRK how bout using a less breathable fabric? I don't know where to get FRK but I can certainly get some nice upholstery fabric which is not as air-transparent as burlap or GoM. I could use that to wrap the panels instead of speaker cloth.


This should help by removing less of the high frequencies and not over-deadening the room, yes?


----------



## Stima




> Quote:
> Originally Posted by *ebr* /forum/post/0
> 
> 
> Stima - I'm afraid you are getting into some things that are very specific to your room so the answers to your questions are going to be "it depends..."
> 
> 
> You have to realize most of the true experts who contribute out here solve the very detailed problems you are asking about for (at least some part) of their living. So, it may be very difficult to get complete answers to your questions in this forum. If you really want to be sure you do this right, I would suggest contacting one of these guys and talking to them about providing you with specific service.
> 
> 
> Now, that being said - someone like Bryan or Terry or Ethan may jump in here and help you out at least to some extent. I am continually amazed at the amount of time, effort, and advice these guys lay out here for free.




I was afraid to list all my basement spec's for the very reason you mention. However I always seem to find the no-win situation on forums. If I ask for help, it seems I am always not giving enough info or giving to much.










Perhaps, If I simply had written my initial post as follows, people (anyone) would reply:


What is the final concensus on OC703 placement as absorption?

What do people suggest for using a riser as a bass trap?

Can bass traps go behind a screen?


----------



## BasementBob




> Quote:
> OPTIMAL is to get the wave at a quarter wavelength from the wall. This does not mean that you can't be effetive at other places. This does however explain why spacing panels off the wall helps - you're getting closer to longer waves' 1/4 length spacing from the wall.



Close.

Porous absorbers are velocity absorbers -- they absorb the most where the wave is moving the fastest. Spacing them off the wall does extend lower frequency absorbtion for the same cost in material.

For a sine wave the highest velocity is at the 1/4 and 3/4 wavelength points.

But

a) most sound doesn't go straight into a wall, so 1/4 wavelength out from the wall is just about meaningless. With 7 speakers, best case is 1/7th of the direct sound is hitting one spot on one wall straight into it. The rest is hitting at some angle. And after a few milliseconds all of the reverberant field can probably be considered fairly diffuse (all angles). Although the rear wall, relative to the front center speaker, might apply to this 1/4 wavelength (not a diffuse absorbtion test like those at http://www.bobgolds.com/AbsorptionCoefficients.htm ), certainly all the sound hitting the first reflection point absorbers wouldn't be going straight-in-and-straight-out from the fronts because it's all hitting at an angle.

b) most sound isn't a sine wave, thus it probably doesn't have its maximum velocity at 1/4 wavelength

c) Just because the absorber is most efficient at the highest velocity part of the wave (1/4 wavelength for a sine wave), that doesn't mean it doesn't still work well at lower frequencies. As long as the air is moving it still works, just to a lesser degree. 701 plain 1" on wall has a 0.17 absorbtion coefficient at 125hz, even though 1" 1/4 wavelength would be 3390hz.

d) I think that most sound is travelling wave (as opposed to standing) may be relevent too.



> Quote:
> There are several things that control how deep an absorber will reach effectively.
> 
> ... - Density (slow down larger waves more per inch of thickness)



Density is not a guarantee that it will work better at lower frequencies. There's not a lot of dependable lab work at under 100hz. One thing that higher density is known to do is reflect high angles of incidence for higher freqeuncy sound -- thus high density shouldn't be used for first reflection point absorbers, although you might try it on the rear wall.

Normal vs Grazing incidence 



> Quote:
> The idea is to bring the decay time in the room down to an even balance across the whole spectrum.



Actually the best thing to do is to match the DVD recording engineer's RT60 spectrum, but that's impossible. Jeff of Auralex fame has done thousands of rooms, and he managed to get about two of them +-3db from 100hz to 8000hz. A little extra in the bass is apparently ok.


This is a pretty good comparison of absorbtion between

a) 4cm on the wall

b) 4cm, with a 4cm space behind it

c) 8cm on the wall
Theoretical Effect of Moving an absorber out from the wall 


Note how absorbers flat parallel to the wall tend to absorb a lot of HF, but little LF, and it's pretty much a gentle slope between them with no peaks (other than the right hand side).

A lot of things you're likely to have in your HT, like carpet, have this absorbtion trend.


A corner absorber has an absorbtion curve like this
Studiotips Corner 

Note how its got a peak of absorbtion near 100hz, and the higher frequencies are relatively lower absorbtion.

This is one of the few (only?) porous things that have a different absorbtion trend.




> Quote:
> That should keep the room alive



Actually you want the room to be fairly dead. Not anechoic chamber dead, but certainly not 'live'.


----------



## vinyl




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Actually you want the room to be fairly dead. Not anechoic chamber dead, but certainly not 'live'.



Great post Bob - The above statement couldn't be truer for HT.


----------



## Tweakophyte

Hi Bob-


Was that corner chunk profile pulled from a thread? Is that "corner chunk" the version with the 24" face, or the "super chunk" with the 34" face (both are called "corner chunk" from what I can tell.


I am still wonder what the best bass trapping configuration is for 3 pieces rigid fiberglass... 6" thick corner trap or corner chunk with a 24" face. I could not find a direct comparison in the links you helped me with (only the "super chunk" vs corner trap).


Also, based on that normal vesus grazing pic you posted, it seems you should cover first reflection panels made with OC703 with something fluffier to improve the high-frequency absorbtion profile.


----------



## Stima

Just wanted to say thanks to -BB- for the PM.










I will do some more reading\

esearch and then re-post.


----------



## bpape

Off to a meeting pretty quick - will try to post some answers later.


Bryan


----------



## BasementBob

Tweakophyte:



> Quote:
> Was that corner chunk profile pulled from a thread? Is that "corner chunk" the version with the 24" face, or the "super chunk" with the 34" face (both are called "corner chunk" from what I can tell.



You might have noticed that there are no numbers on the vertical axis called "absorbtion". So basically I meant all of them. I was speaking more of trends than actual absorbtion coefficients. (That said, the data I used to make the graph was from the 24" face with 4" material Studiotips Corner Absorber.)




> Quote:
> I am still wonder what the best bass trapping configuration is for 3 pieces rigid fiberglass... 6" thick corner trap or corner chunk with a 24" face. I could not find a direct comparison in the links you helped me with (only the "super chunk" vs corner trap).



That sounds like "Hi doctor, I'm an 18 year old olympic athlete. I found these two containers of pills on the ground. This bottle says it's to be taken during a stroke to reduce future problems, and this bottle says it's to be injected during a heart attack. Which should I take every day?"


It's called acoustic _treatment_.


Isn't it better to start with an acoustic problem you're trying to solve, and then build treatment that corresponds to the problem, and then measure before and after to see if its actually done what it was supposed to?



> Quote:
> 6" thick corner trap or corner chunk with a 24" face



I believe you mean that both would have a 24" face, one is full of fiberglass, and the other has an airspace behind it. And those are compared at studiotips (4" with airspace and 24" face, vs full of fiberglass chunk with 34" face) .


The short answer about the 'difference' between two with a 24" face, one full and the other with 6" of fiberglass and air behind, is not much. From 200hz and up they'd probably be identical. From 63hz and below the chunk that is full would probably have significantly more sabins of absorbtion. Between 63hz and 200hz I'm not sure, but I'd bet that the full one would have a bit more absorbtion.


The question "which is the best absorber" is the wrong question to ask. If you have a room that's acoustically perfect, then adding Auralex MegaLENRDs would be a bad thing. If your immediate problem is flutter, then corner traps are a waste of money. If the problem is a floor ceiling mode, then placing absorbtion on the walls probably isn't going to help. If it's an imaging problem caused by SBIR, then ceilingwall traps aren't going to help. The question is either "what's the complete acoustic treatment plan that I need for my room", or "what's the next thing that will give me the biggest improvement of sound for my dollar for my room". In all cases the words "for my room" are important, and relative to what's going on in that room right now. Because for which is best for the room, that depends on what else is in there, and how sound is bouncing around.


Start a thread. State what's in the room right now (furniture, carpet, treatment), with drawings with measurements and photos. State what you perceive the acoustic problems to be (observations, anomolies, difficulties, examples, and/or measurements). State the budget, restrictions (like floorspace), and your "criteria for success". There are other acoustic issues than absorbtion, and moving speakers and furniture is a lot cheaper and easier.


----------



## Ready2Buy




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Close.
> 
> Porous absorbers are velocity absorbers -- they absorb the most where the wave is moving the fastest. Spacing them off the wall does extend lower frequency absorbtion for the same cost in material.
> 
> For a sine wave the highest velocity is at the 1/4 and 3/4 wavelength points.
> 
> But
> 
> a) most sound doesn't go straight into a wall, so 1/4 wavelength out from the wall is just about meaningless. With 7 speakers, best case is 1/7th of the direct sound is hitting one spot on one wall straight into it. The rest is hitting at some angle. And after a few milliseconds all of the reverberant field can probably be considered fairly diffuse (all angles). Although the rear wall, relative to the front center speaker, might apply to this 1/4 wavelength (not a diffuse absorbtion test like those at http://www.bobgolds.com/AbsorptionCoefficients.htm ), certainly all the sound hitting the first reflection point absorbers wouldn't be going straight-in-and-straight-out from the fronts because it's all hitting at an angle.
> 
> b) most sound isn't a sine wave, thus it probably doesn't have its maximum velocity at 1/4 wavelength
> 
> c) Just because the absorber is most efficient at the highest velocity part of the wave (1/4 wavelength for a sine wave), that doesn't mean it doesn't still work well at lower frequencies. As long as the air is moving it still works, just to a lesser degree. 701 plain 1" on wall has a 0.17 absorbtion coefficient at 125hz, even though 1" 1/4 wavelength would be 3390hz.
> 
> d) I think that most sound is travelling wave (as opposed to standing) may be relevent too.
> 
> 
> Density is not a guarantee that it will work better at lower frequencies. There's not a lot of dependable lab work at under 100hz. One thing that higher density is known to do is reflect high angles of incidence for higher freqeuncy sound -- thus high density shouldn't be used for first reflection point absorbers, although you might try it on the rear wall.
> 
> Normal vs Grazing incidence
> 
> 
> Actually the best thing to do is to match the DVD recording engineer's RT60 spectrum, but that's impossible. Jeff of Auralex fame has done thousands of rooms, and he managed to get about two of them +-3db from 100hz to 8000hz. A little extra in the bass is apparently ok.
> 
> 
> This is a pretty good comparison of absorbtion between
> 
> a) 4cm on the wall
> 
> b) 4cm, with a 4cm space behind it
> 
> c) 8cm on the wall
> Theoretical Effect of Moving an absorber out from the wall
> 
> 
> Note how absorbers flat parallel to the wall tend to absorb a lot of HF, but little LF, and it's pretty much a gentle slope between them with no peaks (other than the right hand side).
> 
> A lot of things you're likely to have in your HT, like carpet, have this absorbtion trend.
> 
> 
> A corner absorber has an absorbtion curve like this
> Studiotips Corner
> 
> Note how its got a peak of absorbtion near 100hz, and the higher frequencies are relatively lower absorbtion.
> 
> This is one of the few (only?) porous things that have a different absorbtion trend.
> 
> 
> 
> Actually you want the room to be fairly dead. Not anechoic chamber dead, but certainly not 'live'.



Wow, what a great post!!! I think your point that a 1" panel still works at 125 Hz even though the popular "quarter wavelegth" theory states that maximum absorption happens for waves of frequency 3390 Hz and higher is an excellent point. Maybe a better theory is needed to understand this.


With regard to density, here is another observation. From your site I see the following absorption coefficients at 125 Hz:


701 plain 1" 0.17

703 plain 2" 0.17

705 plain 2" 0.16


Doubling up on both density and thickness did not change the absorption coefficient. Can we attribute this to bad measurements or is it real?


With respect to the measurements you posted on the wall with zero degrees incidence angle, the 4cm/4cm panel absorbs better than the 8cm/0cm panel even down low. Why? Meanwhile for diffuse sound field, the 8cm/0cm is best as would be expected. In any case, your graph clearly shows that the airgap does improve absorption under all circumstances. It also proves that panels on/parallel to the wall do not absorb low frequency sound very well.


Now WHY does the corner absorber show a large peak at 100 Hz? Does it have something to do with the air column between the absorber and the two corner walls?


The more you think you understand this stuff the more questions arise ...


John


----------



## Ready2Buy




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> The question is either "what's the complete acoustic treatment plan that I need for my room", or "what's the next thing that will give me the biggest improvement of sound for my dollar for my room". In all cases the words "for my room" are important, and relative to what's going on in that room right now. Because for which is best for the room, that depends on what else is in there, and how sound is bouncing around.



Hi Bob,


What happened to the popular:


"You can't have too many bass traps"


I thought this was true for any room that doesn't already have corner treatments. Is this NOT true?


John

PS: Thanks for all the help you provide in this forum and the outstanding website you keep.


----------



## BasementBob

Ready2Buy:



> Quote:
> Doubling up on both density and thickness did not change the absorption coefficient. Can we attribute this to bad measurements or is it real?



It's real.

125hz is well within the acceptable results testing range. (lower frequencies are not)

However, two things:

1) The same sample measured the same way in multiple labs has this uncertainty 

2) The effectiveness of absorbtion drops as you put more absorbtion into a room. These tests/results were done in a large reverb chamber, with an 8'x8' sample in the middle of the floor. If you do the same thing, you'll get the same results. If you put these things into your room, still flat on a surface and away from other surfaces (e.g. the middle of a wall), you'll get different values, but with a similar TREND.



> Quote:
> It also proves that panels on/parallel to the wall do not absorb low frequency sound very well



I hope you mean 'shows', rather than 'proves'.

Mostly I just wanted to show more detail than the simple statement

4" on the wall IS LESS THAN 4" spaced 4" out from the wall IS LESS THAN 8" on the wall

Because the graph shows the relative difference as well.



> Quote:
> Now WHY does the corner absorber show a large peak at 100 Hz?



Nobody knows. There are no standards for corner trap measurments. Some experts have a half dozen educated guesses, all possibly true to greater or lesser degrees. One of my favourites is "edge effect without edges" -- think outside the corner trap too.


The corner trap measurements available to the public are

a) http://forum.studiotips.com/viewtopic.php?t=536 

b) http://www.gikacoustics.com/absorption.htm 

c) http://www.realtraps.com/data.htm 

In all cases assume the tests are performed honestly, but don't take the values out of context. They are valid only for the way they were installed, and shouldn't be compaired. A little fiddling and I can make any of those products absorb more than the others at any frequency you'd care to name. Where the exact test is not described, it's like providing no information at all, other than perhaps the TREND. And the TREND is ultimately possibly all you could use anyway, because your room is not a reverb chamber. The studiotips example goes on and on about how the test is valid for comparison between the devices they tested, but can't be used outside of that narrow scope.


----------



## BasementBob

Ready2Buy:


> Quote:
> "You can't have too many bass traps"
> 
> I thought this was true for any room that doesn't already have corner treatments. Is this NOT true?



I think Ethan Winer started that quote. And for the kinds of rooms that you and five of your friends are likely to walk into in your lifetime, and Ethan's experience installing his traps as corner traps into typical rooms, it's an honest observation.


But corner traps are not only bass traps, they affect higher frequencies too, so I'd have to disagree with your variation on his words. Also, corner traps are not the only bass traps -- I can't think of a DE Designed theatre that has a diagonal corner trap in it, but I can think of lots of membrane and helmholtz absorbers in those.


Worst stupid/insane case: if you 80% by volume filled a six-sided-concrete-room with 30hz tuned helmholtz port absorbers (bass traps), and no other treatment, not only would the sound be awful, but you couldn't see the movie because there's these big bass traps between the screen and the wooden dining room chair (as well as everywhere else). Adding another 30hz tuned helmholtz port absorber to the room because "You can't have too many bass traps" wouldn't help.


(BTW, I use the words "DE Designed" to mean something that Dennis was paid to do, as opposed to "DE Style" which is "cover the front wall in absorbtion, and the side and rear walls 50% of the way up". DE Designed is better than DE Style, every time.)


I should mention again, that I give ideas, not advice. I am, by far I suspect, the most _over_thinking amature on this forum. I've been thinking about HT for three years, and what I've got is this: http://www.bobgolds.com/HomeOffice/home.htm Most (all?) people shouldn't delay and waste as much time as I have. I want to do it once, and getting that last 5% of performance is taking me a rediculous amount of time.


----------



## stromand

_I should mention again, that I give ideas, not advice. I am, by far I suspect, the most overthinking amature on this forum. I've been thinking about HT for three years, and what I've got is this: http://www.bobgolds.com/HomeOffice/home.htm Most (all?) people shouldn't delay and waste as much time as I have. I want to do it once, and getting that last 5% of performance is taking me a rediculous amount of time._


BasementBob,


I almost fell off my chair LOL after I read this quote and viewed your pictures. I think your pictures should be titled "What happens when you buy the projector before finishing the construction"


Thanks, sometimes these threads get a little to serious.


----------



## Stima




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> (BTW, I use the words "DE Designed" to mean something that Dennis was paid to do, as opposed to "DE Style" which is "cover the front wall in absorbtion, and the side and rear walls 50% of the way up". DE Designed is better than DE Style, every time.)



Glad you cleared that up. I was a little cunfuzz'd about "DE style", ect.


----------



## Ethan Winer

John,


> "You can't have too many bass traps" I thought this was true for any room that doesn't already have corner treatments. Is this NOT true?


----------



## Ready2Buy




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Ready2Buy:
> 
> The same sample measured the same way in multiple labs has this uncertainty
> 
> 
> One of my favourites is "edge effect without edges" -- think outside the corner trap too.
> 
> 
> And the TREND is ultimately possibly all you could use anyway, because your room is not a reverb chamber. The studiotips example goes on and on about how the test is valid for comparison between the devices they tested, but can't be used outside of that narrow scope.



BasementBob:


Good stuff, brings up even more questions.


(1) From the uncertainty graph you posted I see that measuring absorption below 100 Hz produces errors as large as 50%! If this is the case then all absorption numbers posted by the various bass trap vendors, including the three links you posted, could be half of their posted values! This means that one could seriously under-estimate the amount of low frequency trapping he needs by as much as a factor of 2.


(2) What do you mean by "edge effect without edges"? Is this another concept/design for bass traps? Excuse my ignorance I just started learning this stuff but, like you, I want to do this once and do it right.


(3) I think it's clear from the studiotips example that if you want any bass traping below 100 Hz you have got the fill up the corners of your room. In that comparison graph it looks like the superchunks with the 34" face does a great job below 100 Hz even though its TREND is dropping fast below the 100 Hz peak. It looks like it will still absorb good at 56 Hz where I got a couple of big room modes. (My room is square 20'x20'x8' with carpet and two leather couches in it).


(4) In one of the studiotips corner trap designs the following statement appears:

"Owens Corning 703 is a material which has been used with success, but lower density products of this class may be cheaper and actually work slightly better low in the band." LOWER DENSITY products work better at lower frequencies??? This is contrary to other statements made here and elsewhere that OC-705 is better at lower frequencies because its denser and therefore more difficult for the longer waves to pass through it. Yet another of the conflicting pieces of loose information out there.


(5) The studiotips excel file:
http://forum.studiotips.com/download.php?id=970 

shows the two fiberglass-based corner trap designs. The classic "studiotips corner absorber" was a 2'x8'x4" tower straddling the corner. It was made by stacking TWO 2'x4'x4" OC703 panels. However, the 34"-face "Superchunks" was made using SIX 2'x4'x4" panels. That's three times more fiberglass than the classic design which resulted in only 50% more absorption at 63 Hz. First it is clear to me that this is an unfair comparison. A more fair comparison would be to modify the classic design so that it uses six panels instead of two. The easiest way to have done this is to create a 2'x8'x12" tower using six 4"-thick panels and straddle the corner. I bet the classic design would be better than SuperChunks if it was made three times thicker. The problem with this comparison would be that the 6-panel classic "system" would now have an airgap behind it while the superchunks doesn't. So a fair comparison might have been the 6-panel superchunks against a 4 panel classic (2'x8'x8").


(6) My own thinking led me to a design that was a 2'x8'x24" square tower shoved in the corner. But I only have 63 2"-thick panels and I would 96 to implement this at 4 corners. I am now rethinking that I could go with 2'x8'x10" towers stradlling the corners. I am still thinking about this and other options too.


Best,


John


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> (4) In one of the studiotips corner trap designs the following statement appears:
> 
> "Owens Corning 703 is a material which has been used with success, but lower density products of this class may be cheaper and actually work slightly better low in the band." LOWER DENSITY products work better at lower frequencies??? This is contrary to other statements made here and elsewhere that OC-705 is better at lower frequencies because its denser and therefore more difficult for the longer waves to pass through it. Yet another of the conflicting pieces of loose information out there.



Not conflicting, John. Just more complicated than a simple rule.


There is a tradeoff between density and thickness. Too dense an absorber, though theoretically thick enough to absorb very low frequencies, won't allow sound waves to penetrate sufficiently to its entire depth. So for an absorber of large depth, a less dense material works better beyond a certain point.


An alternative is to add an airspace behind dense material. This lowers the total amount of absorber thickness the waves have to travel through, while still affecting low frequencies comparably. This airspace approach doesn't come for free. You get "ripple" in the frequency response, rather than smooth absorption.


Make sense?


Regards,

Terry


----------



## Ready2Buy




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> But corner traps are not only bass traps, they affect higher frequencies too



I thought one way to deal with this is to use a less breathable fabric that reflects high frequencies. I still don't know what exact fabric to use though.



> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> but I can think of lots of membrane and helmholtz absorbers in those.



I am afraid I can't build those but I sure can throw fiberglass in the corners in vast quantities



> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> I've been thinking about HT for three years, and what I've got is this: http://www.bobgolds.com/HomeOffice/home.htm Most (all?) people shouldn't delay and waste as much time as I have. I want to do it once, and getting that last 5% of performance is taking me a rediculous amount of time.



Nice office/HT combo. But where are the bass traps? I can't see them in the pictures. Are they cleverly hidden from view?


John


----------



## Ready2Buy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> John,
> 
> I have found they can vary by _300 percent_ at 100 Hz and below. But as Bob said you can see trends when testing the same material in the same places in the same lab.
> 
> --Ethan



Thank you Ethan. But if they vary by 300% below 100 Hz, then there is no way of estimating anything. And what am I suppose to make of the "trend" other than it goes down at low frequencies? In fact that's exactly where I need the traps to work!!!


The important thing I am getting is that the more fiberglass you use the better off you are provided that you do something to avoid over-absorbing the high frequencies.


John


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Not conflicting, John. Just more complicated than a simple rule.
> 
> 
> There is a tradeoff between density and thickness. Too dense an absorber, though theoretically thick enough to absorb very low frequencies, won't allow sound waves to penetrate sufficiently to its entire depth. So for an absorber of large depth, a less dense material works better beyond a certain point.
> 
> 
> An alternative is to add an airspace behind dense material. This lowers the total amount of absorber thickness the waves have to travel through, while still affecting low frequencies comparably. This airspace approach doesn't come for free. You get "ripple" in the frequency response, rather than smooth absorption.
> 
> 
> Make sense?
> 
> 
> Regards,
> 
> Terry



Very nice explanation Terry. But how are we supposed to know where the threshold is? And why aren't more people using 705 for corner traps? Seems like 703 or 703-equivalent (i.e., the 3-pound densities) is the flavor of choice from what I see on the net.


Best,


John


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> Very nice explanation Terry. But how are we supposed to know where the threshold is? And why aren't more people using 705 for corner traps? Seems like 703 or 703-equivalent (i.e., the 3-pound densities) is the flavor of choice from what I see on the net.
> 
> 
> Best,
> 
> 
> John



Hi John,


Finding the threshold is part of my business. I design bass traps, other acoustical treatments, and entire rooms for money







. I've spent years studying the theory and practice of sound absorption. You can slog through the equations in the professional literature yourself for a few years, or hire me (low hundred of bucks) to design the bass trap of your dreams







.


I can't reveal my proprietary tricks for free. But I try to give away as much info as practical, and steer people in the right direction.


Regards,

Terry


----------



## Joel DuBay

One of the reasons people steer clear of using OC705 is cost, and if you look at published acoustical data for FRK and FSK 705, you'll see spikes at 100hz. This is not true of all commercially made acoustic panels that use 705, but it is true or many. There is some test data available through Belgian laboratories and US reverb chambers that should some of the best overall results come from using OC 703 (unfaced) as a broadband absorber. The advantages to the DIY guy are that it is easier to work with, offers a wider broadband absorption coefficient, and costs less than half the price of OC705...and..... it is typically more readily available to the DIY'ers.



We'll be publishing a DIY solution at the website that will show you just how to make your own, with little fuss and a high WAF. (wife approval factor).



Stay tuned, and good luck.


----------



## Terry Montlick




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> ...
> 
> At low frequencies, the change in the Diffraction Effect is much more powerful (in sabins) than the increase in surface area -- and since we're ga ga about bass absorbtion, this is worth paying attention to.
> 
> 
> When a porous material is separated, such as in a checkerboard pattern, its absorbtion changes.
> 
> Usually more absorbtion in the bass, with little change in the trebble
> 
> "The discontinuity in the wave field at the edge of the specimen create a diffraction effect that warps the sound field to make the specimen appear as much as a quarter-wavelength larger in each direction." (from Proceedings of Noise Con 90, David A. Nelson, P.E., INCE Bd. Cert., "Diffraction Effect" in Sound Absorption Tests: Why is the sound absorption coefficient greater than 1.00?)



The first paper I have describing this phenomenon is from 1930. !!!


- Terry


----------



## Ready2Buy




> Quote:
> Originally Posted by *Joel DuBay* /forum/post/0
> 
> 
> There is some test data available through Belgian laboratories and US reverb chambers that should some of the best overall results come from using OC 703 (unfaced) as a broadband absorber. The advantages to the DIY guy are that it is easier to work with, offers a wider broadband absorption coefficient, and costs less than half the price of OC705...and..... it is typically more readily available to the DIY'ers.



Hi Joel, thanks for confirming this. Most of the reputable reports on fiberglass absorbers appear to favor the 3-pound densities.



> Quote:
> Originally Posted by *Joel DuBay* /forum/post/0
> 
> 
> We'll be publishing a DIY solution at the website that will show you just how to make your own, with little fuss and a high WAF. (wife approval factor)



Looking forward to your DIY article. Will you be posting it any time soon?


John

PS: The "bag" product idea is quite interesting as it allows for local purchase of the fiberglass which practically eliminates the hefty shipping costs of finished panels. You may want to consider making it available for thicker panels (i.e., 6" and 8" thickness).


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Hi John,
> 
> You can slog through the equations in the professional literature yourself for a few years, or hire me (low hundred of bucks) to design the bass trap of your dreams
> 
> 
> 
> 
> 
> 
> 
> .
> 
> 
> I can't reveal my proprietary tricks for free.
> 
> Regards,
> 
> Terry



I read you loud and clear Terry







I just happen to be one of those guys who must understand the basics prior to attempting to do anything. The goal is to try to acquire enough basic knowledge about a topic so as to not screw my own self (pardon my language) in the implementation phase










Best,


John


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> The first paper I have describing this phenomenon is from 1930. !!!
> 
> 
> - Terry




Hey guys, did we lose a post from BasementBob? (the one Terry is replying to on "diffraction effects")


----------



## Ethan Winer

John,


> if they vary by 300% below 100 Hz, then there is no way of estimating anything. 
And what am I suppose to make of the "trend" other than it goes down at low frequencies? In fact that's exactly where I need the traps to work!!!


----------



## tonybradley

I've been following this thread and will be purchasing my 2" 703 boards in a week or two. I have a VERY general question. I know my room needs treatments as it's a total reflective room now (drywall all around, drywall tiles for drop ceiling, and thin carpet). Currently, any movie with High Pitched sounds (i.e. Menu screen of Jurassic Park III when the claw marks enter the screen) is extremely painful to the ears. Same with the Glass shattering when the machine first enters on War of the Worlds.


Will the panels at first reflections help tame those highs to where they won't be so painful?


I can't localize my surrounds at all. Honestly, you can't even really tell they are there until it's one of the only speakers working. Again, I think this is because it's being covered up so much with all the reflections going on in my room. The volume levels are calibrated. Will the panels help this problem as well?


I've been experimenting with sub placement. Today I found the best place for my room (between the center speaker and the right main). Thing I'm discovering (volume level is calibrated to the same level as other speakers) is that the sub isn't too loud on SOME scenes where it should be. Would the High frequencies that are reflecting all around the room also hinder what I hear from the Sub..maybe drowning it out some? I will be adding bass traps as well, but just wondering if adding the 2" 2x4 panels on the side and front walls will at least help the sub a little. I've ran some frequency sweeps and there are peaks and dips through the frequency range (of course..no treatments).


----------



## Tweakophyte




> Quote:
> See my Density Report:
> 
> www.ethanwiner.com/density/density.html



Jeez... how could I have missed that one? I skimmed it an am going to read it later...


...hope it's a slow day at work today


----------



## bpape

Tony,


On the bass, it's more likely that the ringing and excessive decay times on the bottom end are in effect covering themselves up. When you get the decay under control, you'll find it smoother and more articulate. It will also likely appear louder and deeper in the bottom end.


As for the highs, it's hard to say. Controlling the reflecions will help to make things more dynamic and 'image' better. Some overlap due to excessive decay times can cause some harshness. What speakers are you using?


----------



## tonybradley




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Tony,
> 
> 
> On the bass, it's more likely that the ringing and excessive decay times on the bottom end are in effect covering themselves up. When you get the decay under control, you'll find it smoother and more articulate. It will also likely appear louder and deeper in the bottom end.
> 
> 
> As for the highs, it's hard to say. Controlling the reflecions will help to make things more dynamic and 'image' better. Some overlap due to excessive decay times can cause some harshness. What speakers are you using?




I have some older Infinity speakers. RS-5 for the mains and the CC-3 center speaker. My receiver is a Denon 2805. Anything that's high pitched is very painful. I don't even listen at Reference Level (slightly lower). That's why I was curious (in a totally reflective room - carpet on floor and chairs) if reflections could magnify these harsh high frequencies and the treatments would tone them down. For example, a few of my friends watched a couple of scenese from War of the Worlds at my house. When the glass shattered in the buildings, it was screatching loud. My ears were actually hurting. We took it to my friends house who has floor to ceiling carpet (yes I know, bad idea). His sounded so much better, but maybe a little too dead as the glass shatter didn't appear dynamic enough. Are you thinking this could be more my speakers and not so much reflections in the room?


----------



## Ready2Buy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> John,
> 
> 
> See my Density Report:
> 
> www.ethanwiner.com/density/density.html
> 
> 
> It's all in there.
> 
> 
> --Ethan



Hi Ethan,


First let me congratulate you on your report. Nice work and an excellent attempt to fill in the knowledge gap in the density/thickness area. The only problem I have with your work is that the differences you observed at low frequencies between the various densities/thicknesses and mountings appear to be rather miniscule to justfy any really strong conclusions. In fact I am wondering if you are not reporting measurements that are "below the noise level". If you were to repeat this test how sure would you be that you would get the same small differences in these results?


From your density report:


"So what can we learn from these graphs? First, it's evident that for all of the fiberglass types it's better to have twelve thinner panels spread more completely around the room than only six thicker panels covering less total surface area."


I definitely agree with this. It says that for thick panels, more absorption occurs in the first half of material thickness than the last half of material thickness. So spreading thinner material all around produces the conclusion you reached. Spreading does produce more bass absorption but at what cost? Certainly at the cost of consuming more surface area. But the bigger cost maybe that it results in over-absorption of the mid- and high frequencies, a problem we don't want.


Another piece from your report:


"For the density comparisons with 12 panels, in each case increasing the density reduced the ringing time and lowered each mode's Q more than the less dense versions."


This is not a quantitative result. How much did it lower it and what are the statistics of the error in your measurements? Also, how much damage did it do to the high frequency range? These are good questions that would need to be addressed in a test like this.


Another:


"This also shows that density appears to become less important when the panels are made thicker."


I like this one, and I believe it. Good result.


Another:


"However, even with only six 6-inch panels 705-FRK still emerges the clear winner, if only by a small amount at 42 Hz."


Now this one I am not so convinced. "Clear winner" but by a nano-Sabin! The magnitude of the difference could easily be attributed to measurement noise.


John


----------



## Ready2Buy




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Will the panels at first reflections help tame those highs to where they won't be so painful?



Hi Tony,


If you already have a finished room and you spend enough time reading these threads you will notice the following trends emerge:


(1) Buy fiberglass (OC-703 or equivalent) and frame/wrap in fabric

(2) Straddle as much as you can in all corners of you room for bass

(3) Place "thinner" panels on walls/ceiling at all first reflection points

(4) If you have material left-over, consider putting in on the front wall

(5) Make the back wall diffusive (i.e., bookcases will work)


The challenge is to pull this off with style and make everything look good in the room (high WAF). The challenge presented in this last point should not be under-estimated.


Best,


John


----------



## bpape

Tony.


In a former life long ago and far away, I used to sell the Infinity's you have. Yes. They can be a bit forward. IMO, it's not so much the highs as it is the upper mids and the xover execution in those speakers. I do think that taming the reflections and the overall decay time will help. Those tweeters are pretty beamy so getting them under control should be relatively easy in comparison to some other drivers.


When you went to the other house, did you take your speakers? Just trying to compare apples and apples.


----------



## Ethan Winer

John,


> I am wondering if you are not reporting measurements that are "below the noise level". 
This is not a quantitative result. How much did it lower it and what are the statistics of the error in your measurements?


----------



## Ready2Buy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> John,
> 
> > how much damage did it do to the high frequency range?


----------



## tonybradley




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Tony.
> 
> 
> In a former life long ago and far away, I used to sell the Infinity's you have. Yes. They can be a bit forward. IMO, it's not so much the highs as it is the upper mids and the xover execution in those speakers. I do think that taming the reflections and the overall decay time will help. Those tweeters are pretty beamy so getting them under control should be relatively easy in comparison to some other drivers.
> 
> 
> When you went to the other house, did you take your speakers? Just trying to compare apples and apples.




I guess I need new speakers (refering to them in your past life is a bad sign)










Unfortunately, I did not take my speakers to his place, which is my next project. I've had these speakers for about 6 or 7 years. I've never noticed them this screatching until this room with the Denon receiver.



> Quote:
> Hi Tony,
> 
> 
> If you already have a finished room and you spend enough time reading these threads you will notice the following trends emerge:
> 
> 
> (1) Buy fiberglass (OC-703 or equivalent) and frame/wrap in fabric
> 
> (2) Straddle as much as you can in all corners of you room for bass
> 
> (3) Place "thinner" panels on walls/ceiling at all first reflection points
> 
> (4) If you have material left-over, consider putting in on the front wall
> 
> (5) Make the back wall diffusive (i.e., bookcases will work)
> 
> 
> The challenge is to pull this off with style and make everything look good in the room (high WAF). The challenge presented in this last point should not be under-estimated.
> 
> 
> Best,
> 
> 
> John



My wife is cool with whatever I do to the dedicated room. I already have my plan on how I"m going to do the treatments. Now to just find the time with two little ones running around.


----------



## Ciscokid

Hi all, I am just beginning to change my family room into a theatre area. I know its not the perfect spot for it since my home is a totally open floor plan. I need to pick your brains on some ideas to help my room out (acoustically). The biggest thing bothering me is echo. Here are the dimensions of my room. 13.5 wide by 21 feet long with 8 foot ceilings. This is just my Family room,its another 22 feet to the back of the kitchen. The room is rectangle in shape with 2 windows and a fireplace between them on one side. The other wall is solid all the way to 18 feet where there is a hall area that branches off to my bathroom and laundry room.I am setting up a projector in the room. Do I need to worry about the front wall behind the screen? Should i put some absorbtion on this wall? I was thinking of putting a bass trap in both front wall corners. Also putting absorbtion on first reflection points on sidewalls and ceiling, if the wife will let me. She is not to fond of the looks of the panels I have been showing her.









Another concern is not having a back wall. Since my room is open to the kitchen is there anything I can do that will help? I have a soffit at 21 feet that kind of divides the family room and kitchen. My wife had an idea of building a coffer ceiling in the family room. Which I kind of shot down cause I thought it would make the room even worse than it already is.Well Thanks for any information you can provide me.


----------



## bpape

Cisco.


If that's the room you have to work with then you'll just have to work with it.


If you can do the front 2 corners and the side refleciton points, that will help a lot. As for the back being open, well, not much you can do there. Deaden the front wall. That will help overall and also will help minimize issues from the rear. Honestly, that dimension is likely not your biggest issue since it's SO long.


Sounds to me that you have some serious issues in the room middle with glass and brick on one side and drywall on the other. I'd shoot for nice heavy curtains over the windows and panels on the side wall opposite it.


Tony,


If you've not had this problem before, then it's either the room or the receiver/speaker interaction, or both. I'd try to eliminate things one at a time - though IMO going to a room with carpet all over the walls is not a good comparison - sorry.


I'd first try borrowing a different receiver (though the Denon is generally considered anything but harsh - if anything too laid back). Then go back to the Denon and even just go get some decent smaller rugs from HD and tack them to the walls where your reflections are just as an experiment.


----------



## Tweakophyte

Ethan-


Nice write-up. I am still trying to decide what the best way to use 3 pieces of 2" thick rigid fiberglass (each 4' tall due to constraints) for low-to-broadband bass trapping. The original options were to make a 6" thick corner trap, a 24" face cornerchunk, or a 4" thick coner trap with another peice wedged in the corner itself.


Based on it you can almost infer it to be best to make a 4" thick panel ("corner absorber") and use the other peice to cover more area. This is because it looks like there's diminishing returns on pure thickness. Now I am thinking of using the additional piece to maker a wedge for the top of the panel, which would add more surface area.


Also, I wonder if part of what you measured is due to the water splashing effect Bob mentioned, and the top-to-bottom configuration handling that better than the half-wall. (make sense?) Next time (if we're lucky enough) maybe you could double up on the vertical corners and create several thicker top-to-bottom panels instead of half-height panels.


Thoughts?


----------



## Ethan Winer

John,


> By "damage" I meant over-absorption. You can't just try to optimize for absorption at low frequencies without regard to the absorption at higher ones.


----------



## Ethan Winer

Tweaks,


> I am still trying to decide what the best way to use 3 pieces of 2" thick rigid fiberglass (each 4' tall due to constraints) for low-to-broadband bass trapping.


----------



## Ciscokid

Bpape,


Thanks for the information. Now your saying to deaden the wall behind the screen right? Do I need to cover the entire wall top to bottom, or just put some absorbtion panels centered on the front wall behind the screen. Along with the two bass traps in the corners. Should I also do the ceiling if possible at the first reflection point? Thanks again for the information.


----------



## Ready2Buy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> John,
> 
> You continue to miss that this was pure research into the relationship between density and low frequency performance. It is not an article explaining how best to treat a room.
> 
> 
> --Ethan



Ethan,


I got you. As you can see my interest is in the big picture, i.e., how to best treat a room. The entire room and over the entire frequency range, 20Hz-20KHz.


Best,


John


----------



## Tweakophyte




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Tweaks,
> 
> 
> > I am still trying to decide what the best way to use 3 pieces of 2" thick rigid fiberglass (each 4' tall due to constraints) for low-to-broadband bass trapping.


----------



## rsante

I read these posts....then reread these posts and I still come away scratching my head. Highs..mids...lows....density vs. thickness...it's almost enough to make my mind turn to jelly.


Is there a place (or book, or video) that I can get that will show me the basics of acoustics to that I can understand the posters in this forum better? Say, an "Acoustics for Dummies" kinda thing?


----------



## Terry Montlick

Roger,


Try any of the books by F. Alton Everest, such as "Master Handbook of Acoustics." These are highly readable and provide a good layperson's intro to the basics.


- Terry


----------



## bpape

Cisco.


I do recommend doing the entire front wall. There is some disagreement on this but IMO it's important to do it in a multichannel environment. This is done in addition to the bass absorbtion.


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Roger,
> 
> 
> Try any of the books by F. Alton Everest, such as "Master Handbook of Acoustics." These are highly readable and provide a good layperson's intro to the basics.
> 
> 
> - Terry



I just got this book last night. From the little that I have read so far I would recommend it highly. Very easy to read if you have a little bit of technical background.


----------



## Ethan Winer

John,


> my interest is in the big picture, i.e., how to best treat a room.


----------



## Ethan Winer

Roger,


> Is there a place (or book, or video) that I can get that will show me the basics of acoustics to that I can understand the posters in this forum better?


----------



## Ethan Winer

Tweaks,


> My thought is with half-height panels that don't have the benefit of two tri-corners you could cap-off the open end of a simple corner panel and trap some portion of the splash. If anything it would add a small amount of surface area to the bass trap.


----------



## Joel DuBay




> Quote:
> Originally Posted by *rsante* /forum/post/0
> 
> 
> I read these posts....then reread these posts and I still come away scratching my head. Highs..mids...lows....density vs. thickness...it's almost enough to make my mind turn to jelly.
> 
> 
> Is there a place (or book, or video) that I can get that will show me the basics of acoustics to that I can understand the posters in this forum better? Say, an "Acoustics for Dummies" kinda thing?




Roger, I understand that acoustics information here and elsewhere can be confusing. There are many books available and many additional resources on the net that make the complicated matter of acoustics, much easier to digest. One way to understand acoustical "treatment" is to visualize it. You might be able to grab more of the info available via its practical application. For instance, you can see an acoustically treated room in this diagram. Typical Home Theater with Acoustic Treatment And, you can view a 3D image tour of an acoustically treated home theater here: Tour an Acoustically Treated Home Theater This Quiktime movie is about 6MB, but gives you a good idea of how a room is typically treated. Hopefully, images with help information make sense.



I hope this helps.


Cheers,


----------



## Ready2Buy




> Quote:
> Originally Posted by *Joel DuBay* /forum/post/0
> 
> Tour an Acoustically Treated Home Theater This Quiktime movie is about 6MB, but gives you a good idea of how a room is typically treated. Hopefully, images with help information make sense.
> 
> www.readyacoustics.com



Joel,


Thanks for posting the animation, very easy to understand. Two questions for you regarding the treated room pictures:


(1) The bass traps at the 4 corners from floor to ceiling are only 4" thick. Jon Risch recommends at least 8" thickness to get down lower in frequency. Do you agree or disagree?


(2) Are the 4 panels behind the couch necessary? (They are not at first reflection points)


John


----------



## edfowler

I've waded thru hours of reading and may have missed it. I know it has been asked but I didn't see an answer.


I plan on putting 1" Certainteed duct board on the entire front wall. BUT...


do I drywall it first or leave the studs and the 6" of fiberglass insulation directly behind the duct board?


thanks


ed


----------



## Stima

Ethan,


I have read through many pages on your site. It appears you have done a ton of empherical study from which I am going to base my acoustical treatments.


To that end, can you please advise if I have missed anything:


Bass traps: I don't have space to put bass traps along the walls, but will utilize the corner trapping method. I plan to straddle the rear corners with 24" wide by 4" deep foil backed OC705 covered in any "breathable cloth" with the foil facing the room. Also, I am going to make several columns of stacked and coiled R12 insulation behind my screen wall. (I have a "bay window" area behind the screen, thus no 90deg corners to "straddle").


Mid\\High Wall treatments: 2" OC703 covered in any "breathable" cloth. Floor to ceiling treatment of the "three sides" of my front wall behind the screen, and both side walls just past first reflection. Don't want foil covered OC703 as it refelcts hi's. I also plan to treat the bottom half of the rest of the side walls with OC703 and the entire (floor to ceiling) back wall. The top half will use 1" batting covered by an acoustically transparent cloth (GOM 701). I don't plan to put anything on my ceiling and have thick burber carpet on the floor.



As a sidebar: your article didn't go into sound decoupling between rooms, but I was wondering how a prodcut such as Dynamat would work behind the acoustical treatments? This product would GREATLY increase the weight of the walls. There is a foil covered version that could be used on the upper half of the walls to preserve "reflectiveness". Any thoughts?


Thanks a bunch,

Stima


----------



## bpape

John.


The panels in the rear of the room and on the rear sides are more for overall decay time control rather than early reflections. It is important to have absorbtion throughout the space for efficient control.


As for the bass absorbers, various things will work. 4" of a denser material straddling a corner with some space to the boundary will work well. If you're going to use a less dense material then more thickness added to the mix will certainly help.


----------



## Joel DuBay




> Quote:
> Originally Posted by *edfowler* /forum/post/0
> 
> 
> I've waded thru hours of reading and may have missed it. I know it has been asked but I didn't see an answer.
> 
> 
> I plan on putting 1" Certainteed duct board on the entire front wall. BUT...
> 
> 
> do I drywall it first or leave the studs and the 6" of fiberglass insulation directly behind the duct board?
> 
> 
> thanks
> 
> 
> ed




Ed,


There are a number of ways to do this. For better bass response, insulating behind you drywall will work well. However, this will do little to help your first reflections. If I am seeing your wall and room layout in my head correctly, using rigid insulation behind the drywall might offer a better aesthetic, but you will probably want to do 'some" first reflection treatment as well there. But, not so much that you lose all of your highs.


----------



## Ethan Winer

Stima,


> please advise if I have missed anything: 
your article didn't go into sound decoupling between rooms


----------



## Ready2Buy

Any comments on the following materials for wrapping fiberglass :


(1) First polyester batting:

http://storesonline.com/site/490194/...M-CG-2028-CASE 



(2) Then grille cloth:

http://www.partsexpress.com/pe/pshow...44&rak=260-335 



I am a little unsure about the polyester batting. There are so many different types, weights, lofts, etc that it is not clear which one works best with the fiberglass trap. (For example I have seen conflicting information on the internet boards regarding whether it should be low loft or high loft.) Please help on this one.


I am now converging on the following process for bass traps:


-First tape together several 2"-thick fibeglass boards

-Then wrap the assembly in polyester batting

-Then insert into wood frame

-Then wrap frame with grille cloth and staple to wood in back

-Then vacuum the surfaces of the fabric

-Then bring inside the house and place straddling the corner

-Done. Now go build the "thin ones" for first reflections.


John


----------



## jimsiff

I've read through the thread, and I've put together a rough draft treatment plan.


My HT is a multi-purpose family room with bar. It's roughly 14'10" x 18'6" with 8' ceilings. The floor is berber carpet and pad over a concrete slab. The two outside facing walls are 1' concrete covered in drywall up to 4', with standard 2x6 stud and drywall from 4' to the ceiling. The other walls are stud and drywall. WAF dictates general theater layout and furniture positions, so I have put together my plan based on those requirements.


I have included a few pictures of the room as well as a drawing showing my treatment plan.











































I would appreciate feedback on my general layout and treatment plans. I plan to first find the best spot for my sub within my available areas, then treat the room, then use my BFD to fine tune the bass FR.


I have some questions as well:


1) For my corner traps, I'm contemplating either an 8' 4" thick panel across the corner, or a "super chunks" style trap. Would I gain a lot of absorption by going with the "super chunks" style trap? It would use roughly 50% more material.


2) What material (acoustical cotton, mineral wool, fiberglass) would be most suitable for a kid friendly environment? I've got a toddler and 6 and 7 year old. I plan on covering whatever I use with grill cloth or muslin.


3) Where can I find absorption coefficients for 8# minneral wool vs. 4" acoustical cotton vs. 4" OC703/705? Is there a significant difference between the three?


4) If you look at my pictures and drawing, the first reflection points for my L/C/R speakers is mostly covered by the back of the couch and loveseat. There is about 1' between the top of the couch and the shelf at 4'. Would I be okay just putting the absorption panel on the shelf, or should I make a 1' tall absorber to treat that small area as well?


Thanks a bunch!


----------



## Terry Montlick

John -

The grill cloth is just fine, but the polyester batting is an unknown quantity. There is no density information given, and without that I don't know the absorption. Generally, when you pack light polyester batting to make it denser, it will "pillow out," and create an unsightly bulge.


Jim -

Acoustic cotton has about the same flow resistance as fiberglass of the comparable density, which is to say it has comparable absorption. Mineral wool has significantly more flow resistance for the same density as the other two, which means it has somewhat different absorption. I don't have measured coefficients for mineral wool this thick (don't think it is sold in 100mm thickness), but it should reach slightly lower in the lowest bass (maybe


----------



## Terry Montlick

John -

The grill cloth is just fine, but the polyester batting is an unknown quantity. There is no density information given, and without that I don't know the absorption. Generally, when you pack light polyester batting to make it denser, it will "pillow out," and create an unsightly bulge.


Jim -

Acoustic cotton has about the same flow resistance as fiberglass of the comparable density, which is to say it has comparable absorption. Mineral wool has significantly more flow resistance for the same density as the other two, which means it has somewhat different absorption. I don't have measured coefficients for mineral wool this thick (don't think it is sold in 100mm thickness), but it should reach slightly lower in the lowest bass (maybe


----------



## Meddy

I am getting close to the insulation phase of my basement theatre and was at HD the other night looking at the different insulation products. I have read about the Roxul Safe'n'Sound as being a good product to use but noticed in the bin next to it the Flexibat. Safe'n'Sound is about $5 a bag more expensive (both cover the same area)/ However the Safe'n'Sound is only a 3" thick batt while the Flexibat is 3.5" thick.


The Roxul website says the Safe'nSound has a density of 2.5lbs/ft3 while Flexibat is only 2lbs/ft3. Am I paying the $5 a package extra for the fire retardant in the Safe'n'Sound or is the 1/2 lb of density worth the extra price paid. Thanks in advance!


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> John -
> 
> The grill cloth is just fine, but the polyester batting is an unknown quantity. There is no density information given, and without that I don't know the absorption. Generally, when you pack light polyester batting to make it denser, it will "pillow out," and create an unsightly bulge.
> 
> Regards,
> 
> Terry



Thank you Terry.


It's becoming apparent to me that most sellers of polyester batting don't even bother to report their densities. Having said that I have found densities from 3 oz to 20 oz. Will all of these work equally well?


I have also seen a post from John Risch stating that we should be using "high loft" batting 0.5"-0.75" thick. I don't know why he said that, he doesn't explain it.


I guess I should say that my goal with the polyester batting is not to improve the absorption but primarily to prevent the fiberglass dust from getting outside the trap. I too have young kids running in the house.


Best,


John


----------



## jimsiff




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Jim -
> 
> Acoustic cotton has about the same flow resistance as fiberglass of the comparable density, which is to say it has comparable absorption. Mineral wool has significantly more flow resistance for the same density as the other two, which means it has somewhat different absorption. I don't have measured coefficients for mineral wool this thick (don't think it is sold in 100mm thickness), but it should reach slightly lower in the lowest bass (maybe


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> ...
> 
> I guess I should say that my goal with the polyester batting is not to improve the absorption but primarily to prevent the fiberglass dust from getting outside the trap. I too have young kids running in the house.
> 
> 
> Best,
> 
> 
> John



Then I would go with acoustical cotton, John.


Regards,

Terry


----------



## Ready2Buy




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Then I would go with acoustical cotton, John.
> 
> 
> Regards,
> 
> Terry



Terry,


Unfortunately, I already have purchased a ton of fiberglass boards. (They are stacked out in the back yard) I just have to find the right material to seal these traps. As last resort I might consider wrapping them in thin plastic bags.


Best,


John


----------



## jimsiff




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> Terry,
> 
> 
> Unfortunately, I already have purchased a ton of fiberglass boards. (They are stacked out in the back yard) I just have to find the right material to seal these traps. As last resort I might consider wrapping them in thin plastic bags.
> 
> 
> Best,
> 
> 
> John




John,


I would wonder whether or not the plastic bag approach would reflect mids and highs too much for your 1st reflection panels? The plastic would certainly be sealed and fairly durable.


I'm thinking aloud here, so discard any ideas you don't think will work. I wonder if you could effectively seal the surface of the fiberglass with some 3M spray adhesive before applying the fabric wrap. Or, there was some fiberglass panel edge sealer manufactured by JM that might reduce or eliminate loose fibers. You could also experiment with wrapping the fiberglass in thin tissue paper or florist paper using 3M spray adhesive to hold it in place before wrapping it in fabric. I would think that would be more acoustically transparent than plastic, but I'm not really sure.


I'm thinking of making panels for the corners using 1x6 frames, and 4" of unfaced 703 sandwiched between a layer of cotton batting, then wrapping the cotton/fiberglass and frame with cheap muslin fabric. The frame, cotton, and fabric should do a decent job of sealing the fiberglass from prying little fingers. For the walls, I'm thinking of doing 1x4 frames with 2" of 703 between cotton batting and muslin.


I could always go with acoustic cotton, but I would want to find a local supplier to reduce shipping costs. There seems to be a significant premium as it is for cotton vs. fiberglass.


----------



## bpape

Absolutely. If you wrap the fiberglas in bags, you'll defeat their purpose as reflection absorbers. Your options are:


1. Put some batting around them that will hold things in but not significantly change their absorbtion characteristics.


2. Sell the fiberglass (should be easy - always people looking) and use acoustical cotton.


----------



## Ready2Buy

Guys, I appreciate your input but I think I made up my mind. I am not going to wrap the fiberglass in plastic bags and I am not going to trade it for acoustic cotton (I bet getting cotton will probably be even harder). I have done enough work already to acquire my fiberglass.


I am going to use 1/4" thick polyester batting on the fibeglass and then frame and wrap speaker grille cloth over it. If we all start itching after I place the traps in the room I will know what to do.










Jim:

If you are building 4 inch thick traps then your 1x6 frames should work fine. You would however be blocking the sides of your fiberglass material with your wood frame. That's an additional 8"x96" of blocked surface area that could be used to absorb even more sound. In my case I'll be using 10" thick traps (five 2-inch boards placed back-2-back) and I want the sides of the traps to be exposed to the sound field. I will probably go with 1x2 front frame and 1x2 back frame with the two attached together using 10" long 2x2 strips. This should let sound come inside the traps from the sides as well as the front and back.


Best,


John


----------



## air2mag

I could sure use everyone's help. I have been reviewing posts for the last six months and have finally worked up the courage to start my theater room. The room is approximately 13 X 19 and is located in the basement (7 foot ceiling). Currently the room is finished in wood paneling. Two of my walls are outside basement walls with 2X4 studs, rolled insulation, and then the paneling over the concrete. The front/screen wall is also 2X4 framing with insulation sandwiched between the paneling and chip board which is in the laundry room. The four wall is pretty much taken up by the stairs. I plan to cover all the walls with GOM. Since my room is already on the small side, I am thinking of removing the paneling and using the existing wall studs for my framing. I plan on using OC 703 and batting as many other have done. I know the 2X4 framing will leave a space of approximately 3 ¼, but I think with the insulation already installed and the 703 it should be just about right. If not, I could always add some batting to make up the difference. I know this is not the optimum solution, but it seems better than going to all the work of adding furring strips over the paneling. Anyway, you all are the experts, what do you think?


----------



## pandasys




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> Guys, I appreciate your input but I think I made up my mind. I am not going to wrap the fiberglass in plastic bags and I am not going to trade it for acoustic cotton (I bet getting cotton will probably be even harder). I have done enough work already to acquire my fiberglass.



Not trying to change your mind, but getting the cotton is easy. See bpape's homepage.


----------



## Ready2Buy




> Quote:
> Originally Posted by *pandasys* /forum/post/0
> 
> 
> Not trying to change your mind, but getting the cotton is easy. See bpape's homepage.



Well it's best to get the material locally to avoid transportation costs. But I did look at bpape's site and he sells 2"-thick cotton for about $28 a piece. I bought 2"-thick fiberglass for a little under $8 a piece. In the quantity I wanted, I am not ready to pay 3.5 times more for the material.


Best,


John


----------



## simon_templar_32

Now I know this is probably a stupid question, so don't jump all over me. Suppose I am trying to control the ceiling reflection. What is wrong with putting a piece of foam (or acoustical cotton, etc.) on top of the speaker cabinet but jutting out front a bit to catch the wave before it even gets to the ceiling?


----------



## bpape

I certainly understand John. Just a couple of clarifications.


1. That price is for 1 single piece.


2. For bass control, there are other products that are considerably more cost effective. The 2" 3lb is primarily sold for reflection point usage.


----------



## Terry Montlick




> Quote:
> Originally Posted by *simon_templar_32* /forum/post/0
> 
> 
> Now I know this is probably a stupid question, so don't jump all over me. Suppose I am trying to control the ceiling reflection. What is wrong with putting a piece of foam (or acoustical cotton, etc.) on top of the speaker cabinet but jutting out front a bit to catch the wave before it even gets to the ceiling?



Not a stupid question at all. This actually works! It comes down to an aesthetic call. If you don't mind a piece of absorber hanging off the top of your speaker, then go for it.


- Terry


----------



## ebr




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Not a stupid question at all. This actually works! It comes down to an aesthetic call. If you don't mind a piece of absorber hanging off the top of your speaker, then go for it.
> 
> 
> - Terry



Wow, what a great idea - especially for those of us who's speakers are hidden behind fabric walls.


----------



## J-dubb16

That is an awesome solution for hidden speakers. How would we calculate the length the absorber would overhang. I would assume that an angular measurement from the speaker cone to the absorber would be needed. But what angle is typical and is it from the tweeter or midrange driver or both?


J-dubb


----------



## bpape

Just be careful when behind a wall. To avoid reflections off the false wall framing you want the speakers pretty close to the fabric. That would likely not leave enough space for sufficient overhang to deal with the vertical reflection on the ceiling.


To figure what you'd need....


If your speaker tweeters are at about ear level, then the reflection on the ceiling will be basically halfway between you and the speaker along a straight line from tweeter to ear. Transfer that to the ceiling (do this all on paper). Then, look at how far up from the tweeter the cabinet top is. Do the trig for that little triangle using the angle established before and the height difference and it should give you the distance out to cover the line from tweeter to reflection point on the ceiling.


Hope that made sense.


----------



## Terry Montlick




> Quote:
> Originally Posted by *J-dubb16* /forum/post/0
> 
> 
> That is an awesome solution for hidden speakers. How would we calculate the length the absorber would overhang.



Another way is a variation on the classic mirror method. With an assistant, place a mirror on the ceiling at the spot where you can see tweeter and midrange drivers reflected in the mirror from your theater seat. Then, just extend the absorber forward until it completely hides the drivers' reflections in the mirror.


Regards,

Terry


----------



## Ktulu_1

Mirrors on the ceiling? Is this the "How to Acoustically Treat Your Bordello" thread?


----------



## LarryChanin

Hi Guys,


Not to be a party pooper, I think this may be more difficult to achieve than you think even if your speakers are hidden behind fabric.


Attached is a drawing of the profile of my room. The drawing focuses on ceiling reflections from the upper center channel speaker. The situation would likely be more problematic for lower speakers such as the mains because the reflection points on the ceiling would be further into the room and would require great amounts of overhanging insulation.


You'll notice that even for the first row of seating, with an upper center channel close to the ceiling, the amount of absorber sticking out to block the first reflection point would put it outside the fabric shadowbox.


Terry: One other question. Even if we could conveniently locate a blocking piece of insulation, wouldn't the edges of the insulation introduce diffraction which would reintroduce the early reflections we were trying to avoid?


Larry


----------



## ebr

I think you're right, Larry. The absorber would probably have to stick out too far to be practical and, If you got the absorber overhanging enough it might also block some direct sound from certain positions.


As Rosanne Rosannadanna would say...


----------



## LarryChanin




> Quote:
> Originally Posted by *J-dubb16* /forum/post/0
> 
> 
> That is an awesome solution for hidden speakers. How would we calculate the length the absorber would overhang. I would assume that an angular measurement from the speaker cone to the absorber would be needed. But what angle is typical and is it from the tweeter or midrange driver or both?
> 
> 
> J-dubb



Hi,


As bpape described we can calculate the reflection points, then position he absorber to intercept the reflection point. If you recall we described the calculation in your Reflection Points thread .


In addition to all the tweeters (some speakers have more than one) we would also need to deal with all the midrange drivers locations. If your seating reclines this would introduce additional complexities since each driver-seating position combination would result in a different ceiling reflection point. The placement of the absorbers would have to handle all the resulting reflection points.


Larry


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ktulu_1* /forum/post/0
> 
> 
> Mirrors on the ceiling? Is this the "How to Acoustically Treat Your Bordello" thread?



What have you got against a Theo K. theater?










Larry -


You won't get significant diffraction unless you use a hard frame for such an absorber. Also, any diffracted sound will be spread out, and _should_ be at a lower amplitude in any direction than specularly reflected sound from the ceiling.


In any case, I think this technique would only be practical for a first row of seats.


- Terry


----------



## LarryChanin




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Larry -
> 
> 
> You won't get significant diffraction unless you use a hard frame for such an absorber. Also, any diffracted sound will be spread out, and _should_ be at a lower amplitude in any direction than specularly reflected sound from the ceiling.
> 
> 
> - Terry



Hi Terry,


Thanks for the response.


No doubt the density of the chosen absorber and its proximity with the tweeter will also determine whether or not we are introducing diffraction problems.


Recently I've been experimenting with those rings you place near tweeters to reduce diffraction. I was hoping to do essentially what simon suggested, but by placing the absorber very close to the tweeter I hoped to avoid the problem I described regarding large amounts of overhanging absorber.


I then measured the frequency response before and after the placement of the absorber. I found that more often than not, for very close placement, this resulted in either hurting the frequency response, or yielded an insignificant change (less than .25 dB). I reasoned that the negative effect on frequency response was probably due to the introduction of more reflections due to diffraction rather than reducing the reflections that were hitting the ceiling.


Larry


----------



## Stima

Ethan,


I have a quick question regarding the OC703.


If you recall I planned the following:


> Quote:
> Mid\\High Wall treatments: 2" OC703 covered in any "breathable" cloth. Floor to ceiling treatment of the "three sides" of my front wall behind the screen, and both side walls just past first reflection. Don't want foil covered OC703 as it refelcts hi's. I also plan to treat the bottom half of the rest of the side walls with OC703 and the entire (floor to ceiling) back wall. The top half will use 1" batting covered by an acoustically transparent cloth (GOM 701). I don't plan to put anything on my ceiling and have thick burber carpet on the floor.



However, after re-re-re-re (you get the point) reading this thread, I believe I still don't have everything correct.


According to some of the very first posts in this thread by yourself and D.E., I should NOT treat the side or back walls from floor to ceiling EVEN at the first reflection points. Rather, I should treat the side and back walls from floor to ear height and then batting above. Also, I should use 1" OC703 NOT 2" everywhere.


If you can't tell, I am ordering my OC703 TOMORROW and really want to get it right.


Thanks for any help here!!

Dan


----------



## bpape

Dan,


I think the issue is that with the front wall and first X of the side walls covered floor to ceiling in 2" material, covering the rest of the walls with a mix AND the whole rear wall floor to ceiling would make it too dead and unbalanced (though better than 1" everwhere).


There are several different schools of thought on how to treat a room. They can use very different methods to achieve the same end. The goals are:


- Get the bass under control (nothing you've adressed above will do that)

- Tame the early reflections

- Kill the front wall

- Get the decay time for the space under control relatively evenly across the board. The target time to shoot for is dictated by your room volume.


Now, HOW you do the above, is up to you. Sounds to me like you're trying to mix a couple different methods and it's not working out well.


----------



## SC Bones

WOW This site is great...something happen to my last post so I will post again....I have a 1200 sq foot basement...I have been looking for help w/ a home theater for MONTHS, until three days ago, when i found this site!!! You guys have tons of pics AND knowledge.....Estimates for a home theater run $30,000 but some of you have spent 1/2 that!!!


Soooo I am thinking about doing most of the work myself....My question is.....is a home theater hard to plan and build....I have most of the tools.....I'm just a little scared to get started.....I have a space in my basement that's 25 x 13'6...I would like to have a 100 maybe 110 inch screen, and two rows of four chairs...do you guys think this room is big enough???? I am concered that I will not be able to get a row of 4 theater chairs w/in the accross 13'6''


----------



## bpape

Don't be scared - there are plenty of people here who will help. I'd recommend starting your own thread with a sketch of the space and what you want to do. Planning is the critical part. Don't get ahead of yourself. Know your goals and plan ahead.


----------



## Stima

bpape,


Thanks for the reply.


I think I have decided upn the following:


Front wall: 1" 703 mounted to 2x4 stud wall with R12 binsulation between studs. (no drywall between 703 and R12)


Side walls: floor to ceiling 1" 703 up to fst refelction for both rows of seating. (will be about to first row actually)


Side walls cont': after first row, will cover up to ear height with 1" 703. Upper "half" will be filled with 1" thick, 10oz batting.


Rear wall: Same as side (cover up to ear with 1" 703)


Sofits: Bottom covered with 1" 703


Bass trapping: Straddle rear corvers (24" surface area from floor to ceiling) with 4" 705 (or 6" 703 if 705 is not available)


Bass trap cont: Behind AT screen\\wall, two stacks of rolled R12 (still in wrapping) from floor to ceiling.



I am hoping all this 703 doesn't result in too dead a room and teh bass traping will be sufficient.


A couple side notes: The walls and ceilings are "floating" and completely seperate (secondary) from exterior walls\\upstairs floor joists, however they only have 1 layer of drywall. My idea was to "decouple" the room while still providing "fleixable" enough walls to reduce room modes. Also, my back row is only a couple feet off the rear wall, so diffusion is not an option.


----------



## THE_COW_IS_OK




> Quote:
> Now I know this is probably a stupid question, so don't jump all over me. Suppose I am trying to control the ceiling reflection. What is wrong with putting a piece of foam (or acoustical cotton, etc.) on top of the speaker cabinet but jutting out front a bit to catch the wave before it even gets to the ceiling?



Unlike general concensus here, I don't think this is a good idea. having any solid surface near the speakers drivers will affect air impedence and will create bass boost at some frequencies.


Do this experiment:


surround your speaker with 4 rigid fiberglass panel. 1 on top, 1 on bottom, 1 left, and 1 right. you won't need any SPL Meter to nitice the difference in bass even if you sit very close to the speaker.


----------



## THE_COW_IS_OK

Another side effect is diffraction in mid-high frequency. Even when using non-wooden frames. Speaker design factors in cabinet construction as the only object surrounding the drivers and thus they are opimized for that. Any other object coming close to the drivers, will affect performance.


----------



## bpape

Stima,


That is a lot and there are some things I'd not do - like the no drywall on the front.


Maybe you should start your own thread to discuss.


----------



## bpape

air2mag,


Sorry your question got lost in the shuffle. You might want to start your own thread on this - there will be a lot of different input.


Bryan


----------



## air2mag

Thanks Bryan I will give that a shot.


Mike


----------



## myfipie




> Quote:
> Originally Posted by *SC Bones* /forum/post/0
> 
> 
> WOW This site is great...something happen to my last post so I will post again....I have a 1200 sq foot basement...I have been looking for help w/ a home theater for MONTHS, until three days ago, when i found this site!!! You guys have tons of pics AND knowledge.....Estimates for a home theater run $30,000 but some of you have spent 1/2 that!!!
> 
> 
> Soooo I am thinking about doing most of the work myself....My question is.....is a home theater hard to plan and build....I have most of the tools.....I'm just a little scared to get started.....I have a space in my basement that's 25 x 13'6...I would like to have a 100 maybe 110 inch screen, and two rows of four chairs...do you guys think this room is big enough???? I am concered that I will not be able to get a row of 4 theater chairs w/in the accross 13'6''



Keep looking around this site.. There are plenty of people that have a room that size and make it work... Just make sure you can fit a bar in it!










Glenn


----------



## Terry Montlick




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Stima,
> 
> 
> That is a lot and there are some things I'd not do - like the no drywall on the front.



I ditto Bryan.


- Terry


----------



## Stima

Terry, Brian...I started my own thread. "Load, Aim, Fire...'


Please feel free to elaborate on anything you don't like in the setup.


I am ALWAYS open for suggestions.


Thx,

Dan


----------



## LarryChanin




> Quote:
> Originally Posted by *SC Bones* /forum/post/0
> 
> 
> Soooo I am thinking about doing most of the work myself....My question is.....is a home theater hard to plan and build....I have most of the tools.....I'm just a little scared to get started.....I have a space in my basement that's 25 x 13'6...I would like to have a 100 maybe 110 inch screen, and two rows of four chairs...do you guys think this room is big enough???? I am concered that I will not be able to get a row of 4 theater chairs w/in the accross 13'6''



Hi,


I think that if you are planning for typical sized cinema recliners that your width dimension will make it difficult to fit four seats across. For example, my four Jaymar recliners are a little narrower than the wider Berlines at a total width of roughly 10 feet, versus 11 feet 5.5 inches for the Berkines (model 90).


Here's a drawing of my configuration in a room that is 15 feet wide.











You'll notice that I had to shift the seating to the left to provide a wider single isle on the right. You should also try to get as much distance as feasible between the seating and wall to reduce boomy bass problems.


If by "theater chairs" you mean ones like this , four of these would be about 8 feet wide. So you should be able to fit four of this type of seating allowing two isles of about 2'9" on either side.


Larry


----------



## Phil Olson

Well, I finally finished reading the entire thread







and one thing I noticed is that there is a general consensus on a balanced absorption through the frequency range, but since everyones room is different, the advice given here is really more of a very rough guesstimate, the true test being measurement and tuning.


When the insulation stuffing begins, etf Acoustics, ($150), can measure RT-30, RT-60, etc. and allow you to know exactly what needs to be done.


Even though this tool costs some coin, there is really no substitute for knowing where you are vs guessing.


Instead of asking "I've installed 10 panels of xyz insulation on the wall and put 2 abc base traps in the corners, what else do I need to do?", the person could just attach his etf graph and that would point to exactly what needs to be done, (more bass traps, less high end absorption, etc.).


Specifically, what I am advocating is that the first bit of advice to give to people embarking on a theater construction project is to pick up at least etf and a cheap mic.


Of course if one is on a seriously tight budget general advice is better than nothing, but if there is room in the budget for insulation, framing lumber, speaker cloth or GOM, etc., spending a little on a tool that tells you when to stop is a small price to pay. It could easily pay for itself by allowing one to apply just the right amount of absorption in the right places.


So am a nuts or what?


----------



## BasementBob

Phil Olson:


Ignoring noise floor, soundproofing, video, seating, HVAC, bells and whistles...


ETF5 is a tool. The trick is to know how to read the graphs, and how to do tests (mic placement, gate times, etc) to get graphs that are easy to interpret. Without correct interpretation, a lot of the information on the graphs is not helpful. Without correct tests, correct interpretation is impossible.


I think the best place to start for anyone is Master Handbook Of Acoustics , and learn what RT60 and SBIR and so on are.


Thereafter there are four types of rooms depending on WAF restrictions

1) a few early reflection and flutter controlling absorbers scattered about the room (DIY, semi-DIY bags, pre-manufactured)

2) corner traps (with or without #1 due to windows etc) - very effective in an otherwise empty room

3) DIY whole 9 yards acoustically - Able to cover any amount of the room surface (e.g. 60% of the room surface) with acoustic treatment. Able to figure out ETF5. You're way beyond corner traps and purchased absorbers if you're doing this.

4) Hire professionals (DE before the room is built, eor Terry after the room is built).


If you're considering #3, then the second book to buy is How to Build A Small Budget Recording Studio From Scratch : With 12 Tested Designs .


Knowing the possibilities (the book MHOA, and others), and knowing what you hear (problems, boomyness, missing frequencies, speach inteligibility, imaging, spaciousness, sweet spot, flutter, etc), and knowing what problems ETF5 detects at the listening position (first test) in details that you don't hear, and knowing how to conduct tests to identify the problem that's causing the anomoly and the limits of ETF5, then knowing how to treat it economically (speaker placement, listener placement, room size and shape, absorbers (porous, membrane, helmholtz), inter-absorbtion effects, diffusers, reflectors, couplers, EQ, etc).


BTW, if you're going to buy ETF5, you might as well pick up their calibrated microphone.


----------



## Ethan Winer

Phil,


You definitely get it, and I'll add just one point:


> etf Acoustics, ($150), can measure RT-30, RT-60, etc.


----------



## mtmason

I've been reading.. a lot... of this thread and been inspired to tackle some accoustic treatments to my Home Theater/Family Room. When I went back to my room to listen with a more critical ear I instinctively turned off my projector, because it was distracting me from really listening to the "room." Then I realized, what did I just do? Maybe I should be starting with silencing my projector (IF 7200). It's not terribly loud, but definitely adds a high frequency sound to the room from mostly the fan and also the color wheel.


I prefer to focus on one thing at a time. Does it make sense to start with a hush box as my rooms most effective accoustical "treatment." Are the typical improvements to a room by adding bass traps and first reflection treatments usually so dramatic that they over shadow noise introduced by a projector? I know a lot comes down to how bad my room sounds now and personal preference, but I'm interested in people's opinions here and wonder for all the talk about sound isolation from outside the room, HVAC, etc... I haven't seen anything about addressing projector noise (could have easily missed it).


Also, what would be the best type of accoustical material to line a hush box with? Thanks for your opinions.


MM


----------



## ebr




> Quote:
> Originally Posted by *mtmason* /forum/post/0
> 
> 
> ...Are the typical improvements to a room by adding bass traps and first reflection treatments usually so dramatic that they over shadow noise introduced by a projector?...



Yes.


That is not to say that a hush box won't do you good. I have no idea how much noise pollution is being introduced there, but, proper room treatments, imo, are one of the best, and least expensive, improvements you can make to your audio system.


----------



## Ready2Buy

This past weekend it rained pretty hard here in beautiful Southern California and even though I had covered the fiberglass with a tarp, a small amount of water still managed to get through it as well as the plastic bags that the fiberglass boards are wrapped with. Today the sun came out and I removed the tarp and relocated the material to a dry spot in the back yard. I am hoping that the sun will dry out the material in a few days but I have also heard that once fiberglass gets wet (even a little) it poses the risk for mold. Is this true?


Is it pointless to expect to dry-out the material or should I just throw away the bottom few boards in the pile that got wet the most?


Thanks guys,


John


----------



## myfipie

John,


You can try to dry it out, but I hate to tell you but it probably is trash! Trust me you will smell it if it does not dry out..


Glenn


----------



## Westshorestudios

Can you soak the wet area in bleach, then put out in the sun? the bleach should kill any mold spores, then you'll just have to let the chlorine smell dissapate.


How thick is the fiberglass and how dense?


----------



## Ready2Buy




> Quote:
> Originally Posted by *Westshorestudios* /forum/post/0
> 
> 
> Can you soak the wet area in bleach, then put out in the sun? the bleach should kill any mold spores, then you'll just have to let the chlorine smell dissapate.
> 
> 
> How thick is the fiberglass and how dense?



They are 2'x4' boards, 2" in thickness, 3 pounds per cubic foot in density. (The brand name is Johns-Manville Insul-Shield IS-300.)


Only the bottom four panels in the pile of 63 look like they are affected because they have a little bit of a rusty looking color in spots. I opened the plastic yesterday and expose the boards to the open air and the sun. This afternoon they look pretty dry except for this discoloration on those four boards. They don't smell though and I put my nose one inch from the boards.


You think they are still good? I mean should I still pour a galon of bleach on them or should I just toss those four?


Thanks guys, I appreciate the advice.


John


----------



## lakeeliza

Is there an alternative product to Green Glue? Thank goodness they are around and seem to be half the cost of Quiet Rock. Still, the price is way beyond my budget. It seems that Viscoelastic glue, is Viscoelastic glue. Is this correct, or is Green Glue something special? I see that 3M makes it, car manufacturers use it, and others have it under other names. This discussion group seems to only talk about Green Glue and wonder if there is anything else out there.


Thank you,

Rick


----------



## myfipie




> Quote:
> Originally Posted by *Ready2Buy* /forum/post/0
> 
> 
> They are 2'x4' boards, 2" in thickness, 3 pounds per cubic foot in density. (The brand name is Johns-Manville Insul-Shield IS-300.)
> 
> 
> Only the bottom four panels in the pile of 63 look like they are affected because they have a little bit of a rusty looking color in spots. I opened the plastic yesterday and expose the boards to the open air and the sun. This afternoon they look pretty dry except for this discoloration on those four boards. They don't smell though and I put my nose one inch from the boards.
> 
> 
> You think they are still good? I mean should I still pour a galon of bleach on them or should I just toss those four?
> 
> 
> Thanks guys, I appreciate the advice.
> 
> 
> John



All you can do is try, but with that said I have read a lot of posts that talk about a mold smell after getting wet.. Hate to see you waste money but just pointing it out to you..










Glenn


----------



## Westshorestudios

I haven't had to deal with the wet fiberglass issue, so take this for what its worth.


Just because a fiber based material gets wet doesn't mean it's ruined or will grow mold and mildew. We wash clothes every day. We then dry those clothes. no problem. Even when we leave the clothes in the washer wet for a couple of days days, and then dry them, no problem.


Your fiberglass boards, if they got a little wet but the next day you put them in the sun to dry, i don't see how they will develop a mold / mildew problem.


Also, mold / mildew spores are everywhere: in our houses, floating in the air, in our cars, in our carpets, in our closets, on newly purchased rigid fiberboards, etc. If, after your boards dry and bake in the sun for a few days, you don't smell mold / mildew mustiness, I think you are fine, even without pouring bleach on them.


Before using bleach, I would test a 1'x1' piece by pouring bleach on it and letting that dry and the bleach / chlorine evaporate. My biggest concern would be a lingering bleach smell.


I just hate to see you throw those fiberboards away for no reason.


Just my .02.


Good luck.


----------



## myfipie

You are totally right you can dry out fiberglass, but you have to make sure it is totally dry.. Problem is if it is moist at all then you rap it, you get into problems...

Just give it a few days out in the sun and see how it goes.. I would take them in at night because of morning dew..


----------



## Ready2Buy




> Quote:
> Originally Posted by *Westshorestudios* /forum/post/0
> 
> 
> If, after your boards dry and bake in the sun for a few days, you don't smell mold / mildew mustiness, I think you are fine, even without pouring bleach on them.
> 
> 
> I just hate to see you throw those fiberboards away for no reason.



WestShore,


Thanks for the advice, I am gonna leave them out there in the sun for another week and if there is no odor by then I'll build them into bass traps. You make a lot of sense my friend



Glenn:


I hear you as well and you may eventually turn out to be right but I am not sure yet that these boards can't be saved. They have been drying out nicely.


Best,


John


----------



## myfipie

I will say that you are out on the west coast so you do have more dry air.. Heck yes a week should do it... If you lived in Florida I would say "sorry charley"!










Glenn


----------



## dknightd

Great thread. I finally made it to the end - yea!

I think all my questions, for now, have been answered.

I'm just posting to subscribe to the thread - couldn't see

another way to do that - probably my mistake.

Anyway, caryy on, and thanks . . .


----------



## Ktulu_1

dknightd, if you click "Thread Tools" on the top or bottom of each thread you can subscribe to the thread and get an email when someone posts to it.


----------



## rmlowz

Hello,


What product can be placed in a room to make it not as bright sounding . Is there a simple solution that can be bought and placed in corners or walls? The room is 15x19 and is already being used as a movie room. I appreciate your help.


rmlowz


----------



## Ready2Buy

Regarding treating the FRONT wall with absorption:


A large projection screen looks great when it's attached directly onto the front wall but how do you treat the first reflections? (can't put fibergalss panels infront of the screen)


I would like to use a fixed-wall screen if it wasn't for the above problem. The alternative is to use a ceiling mount placing the screen about 6" infront of the front wall. Then I can hang fiberglass panels in the 6" inch space between the projector screen and the front wall.


Only problem is that the ceiling mount looks a bit amateurish. Is there a better option?


----------



## Eldoradophoto




> Quote:
> Originally Posted by *rmlowz* /forum/post/0
> 
> 
> Hello,
> 
> 
> What product can be placed in a room to make it not as bright sounding . Is there a simple solution that can be bought and placed in corners or walls? The room is 15x19 and is already being used as a movie room. I appreciate your help.
> 
> 
> rmlowz



This question has a lot of answers. I am not the expert on this, but would refer you to posts in this thread by bpape, and others. If you start reading at the beginning of the thread you'll read a lot about OC 703 (i.e., rigid fiberglass), linacoustic, and other mineral wool type products that can be placed in the corners for bass traps, placed on the walls to absorb at first reflection points, and others. You will likely get more people chiming in if you read this thread and then ask more specific questions oriented toward you're specific situation or to clarify your understanding of the material already posted, since this question when phrased this broadly has been covered pretty extensively.


----------



## bpape

Eldorado is right on the money. Kill 2 birds with one stone by using something soft as a broadband absorber in the corner that will also double for bass control.


To get additional taming, you'll need to address your reflection points - which will NOT be in the corners but are important to cover.


As for treating the front wall, you can still use a fixed screen and still treat the front wall. Do the whole thing. Most screens still have 1-2" behind them. Having some absorbtion behind will not deal much with the highs but will still help in the mids and upper bass a bit and help to focus vocals.


----------



## tonybradley

I did the mirror test for first reflections last night. I did it for all six seating locations (3 in front, 3 in rear). Based on the test, I will need absorption from about the from speakers to the first row. I had originally hoped to make panels and space them out on the wall for a nice clean look. However, they will now have to be butted up against each other (4 Panels) and not sure how good that will look. I've been playing around with some ideas and here is what I'm thinking.


Start the first panel quite low, the next panel a little higher, and so on. Step configuration. I don't care for the horizontal look. Is the goal to be sure the Panel covers the height of the drivers on the speaker? Since I may do the Step approach, will I be good as long as the drivers are covered?


Second Option: Makie a frame that is 8feet long by 4 feet high and inside the frame, place four rigid fiberglass panels side by side and cover with the fabric. I realize this would result in a HORIZONTAL panel, but it would be much bigger. I think I would get better absorption this way as I wouldn't have multiple frames (sides of the frame being reflective) to contend with. Would this still work by butting the fiberglass boards up against each other in one large frame?


----------



## bpape

Either will work. Just make sure you're covering the mid/tweeter height.


I've seen people do the 1 big panel and then sew designs from a couple different colors, like maroon diamonds on black background or the opposite to give it some interest. That way it doesn't look like a monolith.


As for 1 or more frames, sometimes you can use them to your advantage. Many narrower panels (like 6" or so) spaced out can act as both an absorber and provide some diffusion. All you're really looking for is to not have a direct bounce to your ear from the side walls. If a point falls on the side of a frame, then it's going to bounce back off the wall and toward the front again - mission still accomplished - assuming you've deadened the front wall so it will get absorbed there.


----------



## tonybradley




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Either will work. Just make sure you're covering the mid/tweeter height.
> 
> 
> I've seen people do the 1 big panel and then sew designs from a couple different colors, like maroon diamonds on black background or the opposite to give it some interest. That way it doesn't look like a monolith.
> 
> 
> As for 1 or more frames, sometimes you can use them to your advantage. Many narrower panels (like 6" or so) spaced out can act as both an absorber and provide some diffusion. All you're really looking for is to not have a direct bounce to your ear from the side walls. If a point falls on the side of a frame, then it's going to bounce back off the wall and toward the front again - mission still accomplished - assuming you've deadened the front wall so it will get absorbed there.



Thanks Bryan. I'm planning on some sort of design for the wider panels to give it appeal. I think I'll go this way as it's less wood cutting and I think will look better in my room.


----------



## tonybradley

Bryan,


I remember I quickly asked you this question months ago, but can't remember the reason you said this may not be a good idea. After hanging my panels, I was thinking of cutting out a diamond from a piece of 2" OC703, wrapping it, placing velcro on it and the large panel and sticking the diamond in the center to give it a Three Dimensional Look. What would the CONS to this approach be?


----------



## bpape

That would work OK. The only problem is that getting 703 to be wrapped tight so you have nice clean edges can crush the edges. 705 is stout enough to handle it. Or, you could do the drywall corner bead frame thing as it doesn't add much weight and will give you a nice clean look.


----------



## tonybradley




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> That would work OK. The only problem is that getting 703 to be wrapped tight so you have nice clean edges can crush the edges. 705 is stout enough to handle it. Or, you could do the drywall corner bead frame thing as it doesn't add much weight and will give you a nice clean look.



Good idea. I have some spare corner beading for the other drywall work. I"ll experiment with that.


----------



## LLA2

Hello all,


Excellent forum btw.....


I have a typical plaster room measuring 15'x28'x8' that I'd like to turn into a HT, and was wondering if the techniques for treating an existing room are the same as those mentioned on this forum for new construction?


Any advice will be greatly appreciated.


Thanks


tony


----------



## bpape

Welcome to the forum. The answer is somewhat YES and somewhat NO. There are SO many topics that have been covered in this thread that it's hard to address everything that may and may not be the same.


I'd suggest starting your own thread and asking some more specific questions with a description of your space included.


----------



## unclebooboo

Hi,


Is it possible to cover the front wall with wood paneling for aesthetics or does that entirely ruin the whole point of covering it first with absorption panels? Also, I want to cover all of the side and back walls with faux suede fabric over the absorption panels and polyester batting, but does that also ruin the intended acoustic effect?


Thanks,


Bruce


----------



## unclebooboo

Does anyone know of a quality acoustic testing service in Salt Lake City?


----------



## Stima

As the foremost expert in sound absoportion I would say....oh wait, I am just a beginner like you!!!










Actually, the front wall treatment varies between two camps. Dennis says the entire wall NEEDS absoprtion making hard paneling impossible. However, I believe either Ethan or Terry claim front wall absoption is NOT necessary, making paneling o.k. So, you get to choose whom to believe.


For the side and back walls: Suede is not even CLOSE to acoustically transparent making whatever you put behind it for absorption nearly useless. I am sure SOME mids and highs will penetrate teh suede and be absorbed, but not nearly as much as would be with an acoustically transparent cover.


Now, all that said to say this: It's YOUR theater. This is a forum of self proclaimed experts. Do what makes YOU happy...not any of us. If the sound isn't PERFECT but you LOVE how it looks and can compromise the two in your head....then DO IT. Don't let the idea your theater has to have audio perfection stop you from enjoying your hard work!!


----------



## BasementBob

unclebooboo:


Any fabric you can breath through will have no effect on the absorbtion. If you can't breath through the fabric, then it depends on the fabric (vinyl and leather would reflect high frequencies, velvet would absorb high frequencies).

Any fabric you cover the walls in should be fire rated or fire retardant treated.

4x8 wood paneling will reflect mid to high frequencies, and probably the lows too. So, covering absorbtion with wood is well, building a reflective wall.


I like to say I'm not an expert - I give ideas not advice.


----------



## unclebooboo

Thanks for the responses.


I have seen a design that uses fabric panels for the speakers and additional design elements with paneling trim, that should make a good comprimise for me for aestetics and acoustics. I will check the fake suede to see if I can breathe through it, but I suspect I will have to switch to fabric even though it decreases that warm feeling I am looking for.


Thanks again.


----------



## bpape

Well, let's take a quick time out here. Just breathing through it (relatively easily), while OK for a quick test to put in front of treatments is not enough to assure it will be acceptable in front of a speaker.


----------



## Bigsmith

Three of the four vertical wall corners in my theatre have doors in close proximity and thus will not accomodate the typical corner bass trap configuration. I know the tri-corners at the junction of two walls and ceiling can be used, but in my case these are compromised as well.


Do fiberglass panels oriented horizontally to bridge the corners where the walls meet the ceiling (around the perimeter of the room) work as bass traps?


----------



## Stima

Yep, wall to ceiling and wall to floor junctions are both prime places for bass traps. You can pretty much treat as much ceiling to wall intersection as possible and not hurt the sound in the room.


Go with MORE 4" OC703\\705 panels (or 4x1") as opposed to less\ hicker panels.


----------



## Stima




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Well, let's take a quick time out here. Just breathing through it (relatively easily), while OK for a quick test to put in front of treatments is not enough to assure it will be acceptable in front of a speaker.




Agreed. Breathable doesn't guarantee acoustical transparency.


----------



## Don_Kellogg

I currently have 48 Aulex 2" 2x4 foot wedge panels can I use these acoustic panels on side and front walls in place of the owens, and other insulation that has been mentioned in this thread. Also I have 12 large wedge bass traps from Aulex, I plan to use them in the corners to help with Bass. Is this too much, What if I use the 2" on the front wall and then put the bass traps in place as well.


----------



## Ethan Winer

Don,


> I have 12 large wedge bass traps from Aulex, I plan to use them in the corners to help with Bass. Is this too much


----------



## stromand




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Well, let's take a quick time out here. Just breathing through it (relatively easily), while OK for a quick test to put in front of treatments is not enough to assure it will be acceptable in front of a speaker.





> Quote:
> Originally Posted by *stima* /forum/post/0
> 
> 
> Agreed. Breathable doesn't guarantee acoustical transparency.



Come on guys. For the education of the home theater novice please post the answer, not more of the question. I have read more than once in this forum that "breathing through it" is a test for acoustically transparency. Now you both say it isn't without qualifying what is. I am not looking for third party lab verification of your answers but how about a little more detail.


I have been to fabric shops and tested materials I am considering for acoustical treatment covering, curtains, corner bass trap covering, etc., and I have breathed though countless materials with varying degrees of ease/difficulty. My standard has been the closer the material is to speaker cloth the more acceptable it is. But I am prepared to compromise a little for aesthetics. The question is how far should I go?


----------



## Joel DuBay




> Quote:
> Originally Posted by *Don_Kellogg* /forum/post/0
> 
> 
> I currently have 48 Aulex 2" 2x4 foot wedge panels can I use these acoustic panels on side and front walls in place of the owens, and other insulation that has been mentioned in this thread. Also I have 12 large wedge bass traps from Aulex, I plan to use them in the corners to help with Bass. Is this too much, What if I use the 2" on the front wall and then put the bass traps in place as well.




Hey Don, that sounds like a good start! Auralex is a well known, very good product for some applications.


Could you list your room dimensions and any structural anomolies you might have in said room? Would love to help you out and make sure you are getting what you "need".



Cheers,


Joel DuBay Sr


----------



## Joel DuBay




> Quote:
> Originally Posted by *stromand* /forum/post/0
> 
> 
> Come on guys. For the education of the home theater novice please post the answer, not more of the question. I have read more than once in this forum that "breathing through it" is a test for acoustically transparency. Now you both say it isn't without qualifying what is. I am not looking for third party lab verification of your answers but how about a little more detail.
> 
> 
> I have been to fabric shops and tested materials I am considering for acoustical treatment covering, curtains, corner bass trap covering, etc., and I have breathed though countless materials with varying degrees of ease/difficulty. My standard has been the closer the material is to speaker cloth the more acceptable it is. But I am prepared to compromise a little for aesthetics. The question is how far should I go?




Agreed Dave.


The "breathe" test is a standard, albeit non-scientific way of determining if a material is NOT breathable, more so than to determine if it is "breathable". Many fabrics are NOT breathable/ transparent in the acoustical sense. Thick canvas is NOT breathable in the acoustical sense, but, it doesn't (for instance) impede the ability to affect low feequency sound waves when used as a bass trap (only) cover. For speaker covers however, a material must not just be "breathable", it must be VERY easy to breath through. Thin nylon (such as stocking material) is a very breathable fabric, especially when stretched. Grill cloth is "breathable". And as such, this is the standard by which other materials are gernerally judged. In a non-scientific world, I believe as you do, that the more a fabric acts (when breathed through), like speaker cloth, the more likely it is going to work for said purpose. This does NOT have to be complicated, but we certainly can make it so.


Just my tiny 2 cents...



Joel DuBay Sr


----------



## Bigsmith




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> Yep, wall to ceiling and wall to floor junctions are both prime places for bass traps. You can pretty much treat as much ceiling to wall intersection as possible and not hurt the sound in the room.
> 
> 
> Go with MORE 4" OC703\\705 panels (or 4x1") as opposed to less\ hicker panels.




Great, thanks!


----------



## bpape

Wasn't trying to ask questions - just cautioning that what Bob said was true for treatment coverings it isn't conclusive enough necessarily for going in front of speakers.


Now putting it in front of a reflection point absorber that's supposed to absorb highs anyway is just fine. That's what's pretty much always been said here - if you can breathe through it easily, it's OK to put in front of treatments. I don't know that anyone's ever said it was a conclusive test for in front of speakers.


Even some cloth that is relatively easy to breathe through (some of the non FR701 GOM for example) can have some pretty serious attenuation in the high frequencies - hence not acceptable for in front of a speaker.


----------



## Don_Kellogg

The theater is 28' in length 12.5 feet wide and probably a 7.5 average height. Room has been framed out of 2x4's, insulated with R13 thermal acoustical insolation. All walls covered with 2 layers of 5/8" drywall, ceiling has a single layer. I didn't know about Green Glue at the time so the second layer of drywall is held up by drywall adhesive some screws. Floor made of cement, covered with thick padding and carpet. There are 3 doors in the room and there is an arch that opens to the stairwell to upstairs (Door up top). Also one egress window which I have covered with thick curtains and set foam in.


I'm in the process of trying to hack this together while I save to enlist Dennis to do a projob. The room seems to have some what of a flat response according to my Pioneer amp MCACC or what ever it is called







Currently I have the 2" aurlex foam covering the undersides of the soffits, which are 4' (Do to air ducts). The bass traps are in each corner and cover from carpet to soffit. I used the mirror trick to figure out where the side wall reflects are. Other than that there is no treatment.


Two limiting factors for me are width and height, unfortunately we had only 8' ceilings in the basement. I would hack up the floor and lower it but I'm not sure that is a good idea as it would be lower than the footers.


----------



## myfipie




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Don,
> 
> 
> > I have 12 large wedge bass traps from Aulex, I plan to use them in the corners to help with Bass. Is this too much


----------



## BasementBob

myfipie:

Actually, Auralex MegaLENRDs are pretty good broadband absorbers, right down into bass.


----------



## Don_Kellogg

I just wondered I have a bunch of money tied up into these would be nice to use them


----------



## Stima




> Quote:
> Originally Posted by *Don_Kellogg* /forum/post/0
> 
> 
> I'm in the process of trying to hack this together while I save to enlist Dennis to do a projob.



Don,


If you are going to spend the money to fly Dennis from Atlanta to Michigan, may I suggest you STOP NOW and not spend another dime!! I can't see the sense in building your room completely wrong and THEN flying the expert in. You will spend thousands for him to tell you the theater was built completely wrong and would have to be torn down to get it to his standards.


Just a thought....but I am simply paraphrasing what Dennis told me when I did the same thing. (I have the luxury of living in the same town as he, so I saved on the airfare.). If Dennis is brutally honest, you are not going to like what you hear...I didn't.


----------



## Joel DuBay




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> I think I would disagree with Ethan on this point (
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ).. One problem with foam bass traps is not only do they absorb bass (a little) but absorb way more of the high end.. I really think you should look into putting a few bass traps with a membrane system in them.. This will help tame the low end and let the 2 inch foam work on the high end.. It is all about balance in a room.
> 
> 
> Glenn





Interesting. I did not know you were a proponent of membrane systems Glenn. I thought you were of a different opinion. So, do you think that (in general for Home Theaters specifically) corner absorption should not include HF _as well as_ Bass Absorption?


By the way, I don't think that opinion is good or bad, wrong or right....I just think it is interesting and that this discussion is very informative. We certainly never tire of learning.


I am interested to hear your opinion.

(I have an email into you Glenn)





Joel R DuBay Sr


----------



## bpape

I think Glenn's point is well taken. It might be possible to overdo the high frequency absorbtion. That said, Ethan generally is a proponent of FSK faced absorbtion so that would not be nearly as big an issue - and does in fact act as a damped membrane. His MiniTraps are also of a membrane type design.


----------



## Joel DuBay




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> I think Glenn's point is well taken. It might be possible to overdo the high frequency absorbtion. That said, Ethan generally is a proponent of FSK faced absorbtion so that would not be nearly as big an issue - and does in fact act as a damped membrane. His MiniTraps are also of a membrane type design.



That sounds like and endorsement Bryan. And, I do not think that is neccessarily wrong. Are you a proponent as well?



Cheers for a good discussion.





Joel R DuBay Sr


----------



## myfipie




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> myfipie:
> 
> Actually, Auralex MegaLENRDs are pretty good broadband absorbers, right down into bass.



I don't think I said they where bad (if I did then sorry) but not the best thing for bass trapping..


----------



## myfipie




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> I think Glenn's point is well taken. It might be possible to overdo the high frequency absorbtion. That said, Ethan generally is a proponent of FSK faced absorbtion so that would not be nearly as big an issue - and does in fact act as a damped membrane. His MiniTraps are also of a membrane type design.



Actually I was talking about a damped membrane.. Wood panels are great, but not for smaller rooms.. Sorry if I miss typed, I think I still have ski brain from last week.










Glenn


----------



## bpape

Joel.


I'm a proponent of the right mix of materials for a given room. Almost always, some will be faced (damped membrane) and some will be unfaced. I've found it very rare where the room 'falls into place' with all unfaced materials without overdamping the highs.


Glenn,


Gotta get those ski-bunnies out of your dreams


----------



## Scott R. Foster




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> myfipie:
> 
> Actually, Auralex MegaLENRDs are pretty good broadband absorbers, right down into bass.



True that - A true broadband device. Easiest thing in the world to install also.


1) Open box


2) Stack units


3) Open 2nd beer - aaaahhhhh!


Pricey though, at about $75 per linear foot of treatment last time I checked.


That kind of number adds up quick. You could easily spend an additional $2000 on your room's corner treatments alone versus use of one of the available panel type mineral fiber based products - and all that for only modest gains in Sabin content.


If you are even thinking about a DIY solution the cost of ML's is a strong incentive.


----------



## myfipie

"Gotta get those ski-bunnies out of your dreams "


I must say that Whistler Mountain outside of Vancouver offers some really nice bunnies!!! To bad they can spot a poor person a million miles away..










Glenn


----------



## Terry Montlick




> Quote:
> Originally Posted by *Joel DuBay* /forum/post/0
> 
> 
> Agreed Dave.
> 
> 
> The "breathe" test is a standard, albeit non-scientific way of determining if a material is NOT breathable, more so than to determine if it is "breathable". Many fabrics are NOT breathable/ transparent in the acoustical sense. Thick canvas is NOT breathable in the acoustical sense, but, it doesn't (for instance) impede the ability to affect low feequency sound waves when used as a bass trap (only) cover. For speaker covers however, a material must not just be "breathable", it must be VERY easy to breath through. Thin nylon (such as stocking material) is a very breathable fabric, especially when stretched. Grill cloth is "breathable". And as such, this is the standard by which other materials are gernerally judged. In a non-scientific world, I believe as you do, that the more a fabric acts (when breathed through), like speaker cloth, the more likely it is going to work for said purpose. This does NOT have to be complicated, but we certainly can make it so.
> 
> 
> Just my tiny 2 cents...
> 
> 
> 
> Joel DuBay Sr



I agree about the "blow-through" test. It is a quick and dirty way to get some idea of acoustic resistance, as specified precisely in ASTM C522-87, "Standard Test Method for Airflow Resistance of Acoustical Materials." As such, it tells you something about the "DC" resistance -- not as good as the frequency-dependent resistance, but pretty useful.


It is kind of like the acoustician's "hand clap" test to judge the general acoustics of a space. It is also quick and dirty, but gives you some very useful information. Last year there was a visit to a local cavern as part of an Acoustical Society of America function. Leo Beranek, one of the deities of modern acoustics and founder of many of its principles, was along (and going strong after more than 90 years on the planet). The first thing he did in the cavern was clap his hands and listen!


Regards,

Terry


----------



## Joel DuBay

Right on Terry...
























That's quite a signature ya got there!!














Joel R DuBay Sr


----------



## Scott R. Foster

Pfft.. forget about the siggy, check out the web site.

http://www.tmlaboratories.com/ 


Nice pics.










I especially like use of "The Scream" under the title "Symptoms of Inadequate Home Theater Acoustics":











classy AND funny.. you don't see that every day.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Scott R. Foster* /forum/post/0
> 
> 
> Pfft.. forget about the siggy, check out the web site.
> 
> http://www.tmlaboratories.com/
> 
> 
> Nice pics.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I especially like use of "The Scream" under the title "Symptoms of Inadequate Home Theater Acoustics":
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> classy AND funny.. you don't see that every day.



Thanks, Scott! And since that little caper in Oslo I now have it in my private collect...


Oops! Nevermind.


----------



## Don_Kellogg




> Quote:
> Originally Posted by *Scott R. Foster* /forum/post/0
> 
> 
> True that - A true broadband device. Easiest thing in the world to install also.
> 
> 
> 1) Open box
> 
> 
> 2) Stack units
> 
> 
> 3) Open 2nd beer - aaaahhhhh!
> 
> 
> Pricey though, at about $75 per linear foot of treatment last time I checked.
> 
> 
> That kind of number adds up quick. You could easily spend an additional $2000 on your room's corner treatments alone versus use of one of the available panel type mineral fiber based products - and all that for only modest gains in Sabin content.
> 
> 
> If you are even thinking about a DIY solution the cost of ML's is a strong incentive.





Yeah you correct the price was a little steep, I bought 12 of the bass traps, and 48 of the 2 x 4' panels for the walls and soffits. Oh well what can you do I do got to admit it did make the room sound allot better.


----------



## Scott R. Foster




> Quote:
> I do got to admit it did make the room sound allot better.



I bet they did.. Auralex makes good stuff. Their top of the line is highly effective and easy to use... good looking too IMO.


----------



## Don_Kellogg

I saw some of the Auralex ceiling panels in the transporter room on Star Trek The Next Generation. Looks like this stuff has multiple purposes....


I just worrie that maybe this is not as good as the insulation treatments most people are putting behind fabric on the forums. But it did make the room sound better I don't have the ping effect when I clap...


----------



## bpape

The Auralex stuff is perfectly fine for general mid/high decay control and reflection point control. The bass treatments are IMO not as effective. Comparing apples to apples, put 4" of Auralex foam across a corner and compare it to 4" of 703, 705, or mineral wool and the 4" of foam will finish last every time.


The Auralex bass treatments are solid. To compare fiberglass/mineral wool/cotton to them, you'd need to replicate the same solid absorbers of the same dimensions.


Don't get me wrong - if you want something easy to put up and don't mind the look (some like it - some don't) it's certainly an easy - though much more expensive solution.


----------



## BasementBob

bpape:


> Quote:
> Comparing apples to apples, put 4" of Auralex foam across a corner and compare it to 4" of 703, 705, or mineral wool and the 4" of foam will finish last every time.



That seems an unexpected statement.

I wasn't aware that Auralex made uniformly 4" thick foam panels. They make a variety of contoured (e.g. wedge) and 2" designer-fabric looking beveled-edge stuff. Which Auralex product are you thinking of?


----------



## srthomas21

Now I'm confused as hell. My plan was to insulate, drywall and paint. My room is 17 ft wide by 30 ft deep with 8 ft cielings and soffits on both sides of the cieling.


I really don't have the technical skills to figure all this acoustical treatement stuff out so if I dont' do anything is the room going to sound like crap?


It seems like there are a lot of experts that post on this thread so what advice would you recommend for a complete newbie to at least add some acoustical treatement to my room?


From what I've read it seams I should add some type of soundboard to the entire front wall as well as the sides of the room up to ear level.


I really don't want to mess with fabrics and such so if put the soundboard up on the wall and then put drywall over it and paint it would that work or would the drywall defeat the purpose of the soundboard?


Anybody dare to make a summary of the 34 pages of this post geared toward newbies just wanting to add some acoustical treatment to their room without getting technical if that's even possible? Most of the posts on this thread are way way over my head










I found this stuff but I don't know if its any good:

http://www.4seating.com/accessories/...WallPanels.htm 


Thanks


Scott


----------



## bpape

Agreed Bob. I'm just trying to compare apples and apples. At it's thickest point, the Auralex is 2" or 3" or 4" or whatever. You can put 2 pcs of 3" face to face and get solid 4". Just trying to make a fair comparison. 4" of 705 of the same surface area of the LENRD (solid) doesn't seem quite right since thickness plays a part in the equation - not to mention that the LENRD is STILL more expensive.


Scott,


Yes - you're defeating the purpose by putting drywall in front of it. Insulation IN the wall helps with isolation. Absorbtion inside the room is what helps with the in room acoustics.


----------



## Stima




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> ... if I don't' do anything is the room going to sound like crap?



Well, since "crap" isn't defined in acoustical terms, it's hard to get you a yes\

o reply. However, I would say if you're going to spend all the money on a home theater room, you will be disappointed in it's performance if you completely skip sound treatments.




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> ...would the drywall defeat the purpose of the soundboard?



Yes and no. Putting drywall over the acoustical panels make them useless for mid\\high frequency absorption but they will act as very poor base traps. For what you are looking for, however, DO NOT put the panels behind the drywall.



> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> Anybody dare to make a summary of the 34 pages of this post geared toward newbies just wanting to add some acoustical treatment to their room without getting technical if that's even possible?



Basic design:


Mid\\High Frequency Absorption:


Use 1" 3lb (density) rigid fiberglass material (Owens Corning, Johns Mansville, others) on entire front wall (floor to ceiling) and on side walls up to ear height. The ear height number is more a rough AREA and less to do with placement. You can put the panels in the middle of the wall if you desire. You also need to treat several points on the side walls from floor to ceiling. These points are called First Reflection points. It takes two people to find these points. First, place a light at each front speaker location, then have on person move a mirror on the side wall as you sit in the each seat. Watch for the light to appear in the mirror. This is a reflection point and NEEDS to be treated. Repeat for each speaker and each seat. You can also do this for the ceiling if you are feeling adventurous.



Mid\\High Frequency Diffusion:


Since you have a very long room, it would be good to put some diffusion on your rear wall. This can be as simple as book shelves, or as exotic as retail foam diffusion panels found online. Smaller rooms don't need this, but at 30', you should consider it.


Low Frequency Absorption:


Bass traps are a good thing. Typical placement is in each corner either straddling or filling the corner. Typical material is 4" (3 or 5lb density) rigid fiberglass...again Ownes Corning, Johns Mansville, ect. Typically these run from floor to ceiling and are 24" across. These panels can also be placed across ceiling to wall or floor to wall corners.


I hope all this helps. If you REALLY don't want to mess with all this stuff, I would suggest you have a pro come out and install the correct panels in the correct spots for you. They can use premade panels and save you a load of trouble, albeit at a decent cost.


----------



## srthomas21




> Quote:
> Basic design:
> 
> 
> Mid\\High Frequency Absorption:
> 
> 
> Use 1" 3lb (density) rigid fiberglass material (Owens Corning, Johns Mansville, others) on entire front wall (floor to ceiling) and on side walls up to ear height. The ear height number is more a rough AREA and less to do with placement. You can put the panels in the middle of the wall if you desire. You also need to treat several points on the side walls from floor to ceiling. These points are called First Reflection points. It takes two people to find these points. First, place a light at each front speaker location, then have on person move a mirror on the side wall as you sit in the each seat. Watch for the light to appear in the mirror. This is a reflection point and NEEDS to be treated. Repeat for each speaker and each seat. You can also do this for the ceiling if you are feeling adventurous.



So to make this paneling would you use a piece of plywood for the backing and attach the rigid fiberglass to the plywood then cover it with a fabric material? How is it attached to the drywall? With screws or some sort of adhesive?


Can you get the fiberglass from Home Depot or is it more of a specialty item?




> Quote:
> Mid\\High Frequency Diffusion:
> 
> 
> Since you have a very long room, it would be good to put some diffusion on your rear wall. This can be as simple as book shelves, or as exotic as retail foam diffusion panels found online. Smaller rooms don't need this, but at 30', you should consider it.



I am planning on having a bar area on the back wall of the room with cabinets. Would that serve the purpose as far as diffusion goes?



> Quote:
> Low Frequency Absorption:
> 
> 
> Bass traps are a good thing. Typical placement is in each corner either straddling or filling the corner. Typical material is 4" (3 or 5lb density) rigid fiberglass...again Ownes Corning, Johns Mansville, ect. Typically these run from floor to ceiling and are 24" across. These panels can also be placed across ceiling to wall or floor to wall corners.



The entrance to the theater is in one rear corner of the room so I don't think I could put a bass trap there. Any idea how to work around that?


Thanks for your answers. It helps to have it summarized like that. What would you recommend as a fabric covering for the panels? Also I have pillars that outline my 108 inch screen. It would not be aestetically pleasing to have those covered with the sound panels. Would it hurt to leave the sound treatement off the pillars?


Scott


----------



## srthomas21

Ethan,


Thanks for the FAQ page. I'll spend the next couple of nights reading it over.


Scott


----------



## srthomas21

Stima,


I forgot another question I had. As far as the side wall full treatments go, how wide should you make the panels for the first reflection points?


----------



## ifeliciano

Is 0.65¢ a sqr. ft. of JM 814 rigid fiberglass board a reasonable price ?


----------



## Terry Montlick




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> Stima,
> 
> 
> I forgot another question I had. As far as the side wall full treatments go, how wide should you make the panels for the first reflection points?



These reflections are relatively localized, so allowing about half a foot around the boundaries of all your reflection points should be sufficient. Just make sure you've got one or more rectangular panels that cover them all, and round up to the nearest foot.


- Terry


----------



## Stima




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> So to make this paneling would you use a piece of plywood for the backing and attach the rigid fiberglass to the plywood then cover it with a fabric material? How is it attached to the drywall? With screws or some sort of adhesive?



There are several ways to make these panels. If you are going to make them separate from the wall (which is completely acceptable), you can make them like Christmas wrapped picture. (You know, the way they do it in McDonald's around Christmas) Then, hang the panel on the wall with a hook and wire method. You could also integrate these panels into the wall by using furring strips (thin pieces of 1"x2"). Make "picture frames" on the walls and fill the "picture area" with either fiberglass or polyester batting.



> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> 
> Can you get the fiberglass from Home Depot or is it more of a specialty item?



I have never seen Lowes or HD carry the correct product, so I would say no. It took me calling nearly EVERY insulation dealer in my local area before I found the Knauf brand version.




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> 
> I am planning on having a bar area on the back wall of the room with cabinets. Would that serve the purpose as far as diffusion goes?



Yeah, that sounds like a good idea. The front of the bar might be a bit reflective, but the back wall (with shelves, etc.) sounds just right.




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> The entrance to the theater is in one rear corner of the room so I don't think I could put a bass trap there. Any idea how to work around that?



It's rare to find a room that allows you to put traps in every corner. Perhaps you could put a trap that straddles the corner above the door. This corner is called a "tri-corner" and is the MOST important area to treat of any corner. Remember, bass traps are an accumulative thing. In most instances, the more the better. So, if you can't cover an entire corner, but can hit the other three...you are still doing OK. Just consider the fact that ANYTHING you do will be a 1000x better than most home theaters you will ever visit.











> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> 
> Thanks for your answers. It helps to have it summarized like that. What would you recommend as a fabric covering for the panels? Also I have pillars that outline my 108 inch screen. It would not be aesthetically pleasing to have those covered with the sound panels. Would it hurt to leave the sound treatment off the pillars?



Glad to help. I assume I haven't give TO bad of advice as the real experts haven't come screaming as of yet.










Fabric to cover the panels can be almost anything breathable. If you can put the material against your mouth and blow through it without much effort...it is going to be a decent material. The status quo here on the forums is a product called Guilford of Maine. (GOM). It resembles burlap, but much much finer. Also, it is fire retardant making it a acceptable wall covering (code wise.)


For your pillars. If they are to the side or slightly behind your speakers I would say let them be. If they are in front, they really need some absorption just as your walls do.


Again, remember your room has to be pleasing to you for years to come. If covering the pillars looks like crap and your going to cringe every time you see them...then by all means leave them be. It is MUCH better to enjoy your theater then to sacrifice the enjoyment just to make it sound just a little better.


----------



## Stima




> Quote:
> Originally Posted by *ifeliciano* /forum/post/0
> 
> 
> Is 0.65¢ a sqr. ft. of JM 814 rigid fiberglass board a reasonable price ?



Not to bad. I got the Knauf 3lb non-fsk for $0.40 ish and 5lb for $0.60ish. Fsk 5lb was almost double at $0.60ish and $1.10ish.


Ish=I can't quite recal exact price.


----------



## srthomas21

Hi Stima


Thanks again, maybe this isn't as daunting as I once thought. Do you have any pictures of a tri-corner Bass trap?


Also any pictures of these acoustical panels? I'm a picture guy










Is all the GOM fabric basically the same but in different colors and patterns? I went to their website and there are a ton of different choices.


Thanks

Scott


----------



## Stima




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> Hi Stima
> 
> 
> Thanks again, maybe this isn't as daunting as I once thought. Do you have any pictures of a tri-corner Bass trap?
> 
> 
> Also any pictures of these acoustical panels? I'm a picture guy
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Is all the GOM fabric basically the same but in different colors and patterns? I went to their website and there are a ton of different choices.
> 
> 
> Thanks
> 
> Scott



I don't have any pics of anything, but here is a better description:


A tri-corner trap looks like a spider web up in a corner. The trap is triangular shaped and extends from the corner an equal distance.


For acoustical panels...just think of a wrapped gift box. Make a frame with wood, put a back on it if you want to have something to hold the fiberglass boards against (NO front as the fiberglass needs to be exposed to the theater to do any good), and wrap the entire thing in GOM.


The standard GOM used is FR 701 - 2100. There are a BUNCH of colors in 701.


Dan


----------



## dknightd

Hi, I can get Knauf rigid plenum board
http://www.knauffiberglass.com/index...odDetail&ID=16 

3.0 PCF acoustic properties

(48 kg/m3) 2"

(51 mm) .33 .67 1.07 1.07 1.03 1.06 .95


(knauf seems to seems to sell the same plenum liner product as Black Acoustical Board
http://www.knauffiberglass.com/index...odDetail&ID=21 )


or knauf Insulation board (faced or plain - I'd get plain)
http://www.knauffiberglass.com/index...odDetail&ID=12 

3.0 PCF acoustic properties

(48 kg/m3) Plain 2"

(51 mm) .29 .65 1.11 1.13 1.06 1.03 1.00


Both are about $1 per square foot for 2" thick 3lb/ft**3 (the plenum board

is a little more expensive).


It appears to me based on the specs that either would work, but the plenum board has slightly better absorbsion at 125 khz - maybe that is within measurement error.


I'll probably stack these to make 4" think panels.

Will the black polymer overspray cause a problem with this?


I'll be covering with fabric. Do you think the black will show through?


I'd like to use the same fibreglass product for both corner "bass" traps

and first reflection points.


Which one would you recommend using?


----------



## myfipie




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> I don't have any pics of anything, but here is a better description:
> 
> 
> A tri-corner trap looks like a spider web up in a corner. The trap is triangular shaped and extends from the corner an equal distance.
> 
> 
> For acoustical panels...just think of a wrapped gift box. Make a frame with wood, put a back on it if you want to have something to hold the fiberglass boards against (NO front as the fiberglass needs to be exposed to the theater to do any good), and wrap the entire thing in GOM.
> 
> 
> The standard GOM used is FR 701 - 2100. There are a BUNCH of colors in 701.
> 
> 
> Dan



Do not put any kind of solid wood backing on the back of panels.. The air gap between the back of the panel and the corner is very important and the panel will not work if you cover it with plywood.. Even with 2" panels that you put on first reflections should not really have solid wood backings and should be spaced 2" off the wall.


Glenn


----------



## dknightd




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> Not to bad. I got the Knauf 3lb non-fsk for $0.40 ish and 5lb for $0.60ish. Fsk 5lb was almost double at $0.60ish and $1.10ish.
> 
> 
> Ish=I can't quite recal exact price.



What thickness was that for?


----------



## srthomas21




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Do not put any kind of solid wood backing on the back of panels.. The air gap between the back of the panel and the corner is very important and the panel will not work if you cover it with plywood.. Even with 2" panels that you put on first reflections should not really have solid wood backings and should be spaced 2" off the wall.
> 
> 
> Glenn



What should you use as backing then? Also how do you space it 2" off the wall? with furring maybe?


----------



## dknightd




> Quote:
> Originally Posted by *srthomas21* /forum/post/0
> 
> 
> What should you use as backing then? Also how do you space it 2" off the wall? with furring maybe?



furring strip will work fine, but from a cost and labor standpoint just using more

fibreglass seems to make the most sense to me.


----------



## Stima




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Do not put any kind of solid wood backing on the back of panels.. The air gap between the back of the panel and the corner is very important and the panel will not work if you cover it with plywood.. Even with 2" panels that you put on first reflections should not really have solid wood backings and should be spaced 2" off the wall.
> 
> 
> Glenn




YES!! I should have noted about the bass traps and the hard backing not mixing.


For the first reflections, I would be hard pressed to understand why a hard backing flush against the wall would be any different from drywall. Now, if you are spacing your panels off the wall, I could understand that position.


----------



## myfipie

Even for first reflections it is better to space them off the wall. Not only do you get 2" more absorbing (saying that the panel is 2" thick) from sides (this was against the wall and now out in the room) but you get sound coming in from the open area of the back and hitting the wall to the panel.. It will also pick up more of the low end..


Glenn


----------



## Stima

I understand now about spacing, and would agree you wouldn't want a hard backing in that case. However, flush against the wall...I still don't see any harm in a hard backing. Do you agree???


----------



## myfipie

Sure if your going to put it against the wall, but









Hey your in Atlanta also, hello neighbor.


Glenn


----------



## Stima

Fellow Hotlanta resident?


----------



## myfipie

Yes sir!


----------



## Joel DuBay




> Quote:
> Originally Posted by *ifeliciano* /forum/post/0
> 
> 
> Is 0.65¢ a sqr. ft. of JM 814 rigid fiberglass board a reasonable price ?




Depending on where you are geographically, the answer would be "yes".



Joel DuBay


----------



## pepar

A friend's recent visit with an SMS-1 snapped me out of my complacency and lead me back to working on my room's problems. I have a parametric EQ (Rane PE17) on the .1 channel that I had setup when I first built the theater. I used ETF software, but somehow a few bands that I *know* were online bacame bypassed. Re-visiting the EQ and ETF reminded me that I had "cheated" by only looking at the 80Hz and below part of the 20Hz - 250Hz sweep, and that my room is an absolute mess from ~100Hz - 200Hz. Even my 80Hz crossed-over sub (Hsu dual 1220HO's) excites it and excites it to the point where it's 50dB-60dB above the sub's 80Hz & below output. (Very weird.) And I purposely turned off the 7-ch amp so I didn't have to look at their contribution.


Room details: "crooked" walls and ceiling (by 1 degree) nominal 8' H x 13' W x 21' L


False wall in front 24" of room - lined - ceiling and walls - with 2" J-M Linacoustic


2" OC SelectSound - framed, backed and GOM'ed at all first reflection-to-audience points (ceiling, front sides and back)


I have excellent clarity, imaging and front/surround integration. Whispers are crystal clear and sound like whispers. Explosions sound like explosion with no audible distortion.


What and where? I could certainly load up behind the false wall, and I could place "something" in the right rear corner. Head-end and DVDs in the left rear. Soffits are a possibility, too.


Anyway, I think I need bass traps. But what and where? I feel like a noob.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Yes, exactly - you need bass traps. What and where? I though you'd never ask.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Look here:



Thanks, I'm on it . . .


----------



## pepar

I have questions; what's the best way to communicate?


----------



## ifeliciano




> Quote:
> Originally Posted by *Joel DuBay* /forum/post/0
> 
> 
> Depending on where you are geographically, the answer would be "yes".
> 
> 
> 
> Joel DuBay



Joel...Im in the D/FW area in Texas. I checked for oc 703 of the same density as the JM 814 and prices were a bit higher.


Thanks for your reply.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> A friend's recent visit with an SMS-1 snapped me out of my complacency and lead me back to working on my room's problems. I have a parametric EQ (Rane PE17) on the .1 channel that I had setup when I first built the theater. I used ETF software, but somehow a few bands that I *know* were online bacame bypassed. Re-visiting the EQ and ETF reminded me that I had "cheated" by only looking at the 80Hz and below part of the 20Hz - 250Hz sweep, and that my room is an absolute mess from ~100Hz - 200Hz. Even my 80Hz crossed-over sub (Hsu dual 1220HO's) excites it and excites it to the point where it's 50dB-60dB above the sub's 80Hz & below output. (Very weird.) And I purposely turned off the 7-ch amp so I didn't have to look at their contribution.
> 
> 
> Room details: "crooked" walls and ceiling (by 1 degree) nominal 8' H x 13' W x 21' L
> 
> 
> False wall in front 24" of room - lined - ceiling and walls - with 2" J-M Linacoustic
> 
> 
> 2" OC SelectSound - framed, backed and GOM'ed at all first reflection-to-audience points (ceiling, front sides and back)
> 
> 
> I have excellent clarity, imaging and front/surround integration. Whispers are crystal clear and sound like whispers. Explosions sound like explosion with no audible distortion.
> 
> 
> What and where? I could certainly load up behind the false wall, and I could place "something" in the right rear corner. Head-end and DVDs in the left rear. Soffits are a possibility, too.
> 
> 
> Anyway, I think I need bass traps. But what and where? I feel like a noob.



sounds like to me your room is in good shape on the high end but a mess at the bottom.. Yep you guessed it bass traps would be in order I would think.. 4" or thicker rigid fiberglass in as many corners as possible would work pretty well for you..


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> sounds like to me your room is in good shape on the high end but a mess at the bottom.. Yep you guessed it bass traps would be in order I would think.. 4" or thicker rigid fiberglass in as many corners as possible would work pretty well for you..
> 
> 
> Glenn



Thanks, Glenn. While I haven't built a Rialto, I still need to do something aesthetically pleasing, or at least minimally disturbing. And it looks like that'll be a challenge.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Thanks, Glenn. While I haven't built a Rialto, I still need to do something aesthetically pleasing, or at least minimally disturbing. And it looks like that'll be a challenge.



Take your time, you can do it!


Glenn


----------



## Penniman

Quick question:


Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.


I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.


Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?


----------



## swithey




> Quote:
> Originally Posted by *Penniman* /forum/post/0
> 
> 
> Quick question:
> 
> 
> Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.
> 
> 
> I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.
> 
> 
> Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?



AVS member bpape sells this stuff also. You can PM him or check out his WWW site here:
http://www.sensiblesoundsolutions.com/


----------



## pepar




> Quote:
> Originally Posted by *Penniman* /forum/post/0
> 
> 
> Quick question:
> 
> 
> Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.
> 
> 
> I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.
> 
> 
> Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?



Go to the "source." Try an HVAC distributor. In construction jargon, that's "HVAC" as in heating, ventilation and air conditioning. That's where I got both my J-M Linacoustic and OC SelectSound Black. The bigger ones usually have some in stock. The Linacoustic comes in roll and I was able to use our SUV, but I had to rent a big van for the more ridgid OC stuff.


----------



## myfipie




> Quote:
> Originally Posted by *Penniman* /forum/post/0
> 
> 
> Quick question:
> 
> 
> Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.
> 
> 
> I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.
> 
> 
> Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?



Sure you can use the fluffy stuff and compress it.. Only problem is you don't really know what you got after your done.. Bryan is a good source also for oc703..

How many pieces are you looking for? Maybe I could have my supplier drop some off to me and i could send it to you.. I am feeling nice today!!










Glenn


----------



## Terry Montlick

You could compress it by 4x and have something equivalent to Owens Corning 703. But the problem is maintaining this fixed amount of compression.


Try:

Homans Associates

4 Armand Lane, Production Park

Williston, VT 05495

802-863-0355


- Terry


----------



## myfipie




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> You could compress it by 4x and have something equivalent to Owens Corning 703. But the problem is maintaining this fixed amount of compression.
> 
> 
> Try:
> 
> Homans Associates
> 
> 4 Armand Lane, Production Park
> 
> Williston, VT 05495
> 
> 802-863-0355
> 
> 
> - Terry



I did see one panel one time that someone built. The person used chicken wire on the front and back.. Would not be my first choice, but it could work..


Glenn


----------



## Penniman

You guys rock! (And roll, all night long)


Terry,


Homan's carries rolls of 1" Linacoustic 4'x100' for a very reasonable price. They're delivering it to my door on Monday.


Thank you all very much. I love this forum!


Kip


----------



## pepar




> Quote:
> Originally Posted by *Penniman* /forum/post/0
> 
> 
> Quick question:
> 
> 
> Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.
> 
> 
> I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.
> 
> 
> Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?



Try the source that Terry recommended. They either will have the ridgid stuff or be able to get it in a flash.


----------



## pepar




> Quote:
> Originally Posted by *Penniman* /forum/post/0
> 
> 
> You guys rock! (And roll, all night long)
> 
> 
> Terry,
> 
> 
> Homan's carries rolls of 1" Linacoustic 4'x100' for a very reasonable price. They're delivering it to my door on Monday.
> 
> 
> Thank you all very much. I love this forum!
> 
> 
> Kip



One inch won't do much . . . and what it will do may not be desireable.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> One inch won't do much . . . and what it will do may not be desireable.



He could double it up to 2" or make a bass trap with 4"....


Glenn


----------



## myfipie

"You guys rock! (And roll, all night long)"


and party every day!!!!! Every one sing! To bad there is not a little symbol that could breath fire and spit up blood..


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> He could double it up to 2" or make a bass trap with 4"....
> 
> 
> Glenn



Doh! Of course. But that leads me to wonder if it's more cost effective to buy 4' x 50' of 2" than to buy 4' x 100' of 1"?


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Doh! Of course. But that leads me to wonder if it's more cost effective to buy 4' x 50' of 2" than to buy 4' x 100' of 1"?



ha ha ha.. sorry I seee your point now..


----------



## Penniman

I'm going to try the 1" on the front wall behind my speakers. I have room to get as thick as I need in the corners (both front and back walls). I'm also stuffing my columns with it, the first columns are in the first reflection point area. I intend to use it in the ceiling at the first reflection points as well in conjunction with a star ceiling. Away from the first reflection points I am planning on using panels made of 1/4" hardboard, strapped and wrapped in black GOM.


My room is rectangular, 13' x 23.5' x 7.5'. There are three windows on the back wall - each is 22" x 60". The floors are bamboo, but will be covered in front by a large, thick area rug. Behind the 1" material in the ceiling is 6.5" of R19 fiberglass, then 1" rigid foam board, and a 2" air space housing the radiant heating tubes for the floor above it. There will be a row of three and a row of four leather chairs in the room.


I guess I'll play with additional absorbtion on the walls if it's still too bright.


Any recommendations?


By the way, I haven't completed the order with Hamon yet, so I could see if they have the 2" material...


----------



## myfipie

I would stick with the 2" if you can.. Also it is best to space it off the wall 2"...


Glenn


----------



## pepar




> Quote:
> Originally Posted by *Penniman* /forum/post/0
> 
> 
> I'm going to try the 1" on the front wall behind my speakers. I have room to get as thick as I need in the corners (both front and back walls). I'm also stuffing my columns with it, the first columns are in the first reflection point area. I intend to use it in the ceiling at the first reflection points as well in conjunction with a star ceiling. Away from the first reflection points I am planning on using panels made of 1/4" hardboard, strapped and wrapped in black GOM.
> 
> 
> My room is rectangular, 13' x 23.5' x 7.5'. There are three windows on the back wall - each is 22" x 60". The floors are bamboo, but will be covered in front by a large, thick area rug. Behind the 1" material in the ceiling is 6.5" of R19 fiberglass, then 1" rigid foam board, and a 2" air space housing the radiant heating tubes for the floor above it. There will be a row of three and a row of four leather chairs in the room.
> 
> 
> I guess I'll play with additional absorbtion on the walls if it's still too bright.
> 
> 
> Any recommendations?
> 
> 
> By the way, I haven't completed the order with Hamon yet, so I could see if they have the 2" material...



It's sort of the other way around - 1" will absorb the highs, but the highs only leaving everything else. 2" will absorb lower frequencies, but even it will leave the mid- and upper-bass virtually unaffected. Check my link and scroll through the pages. I've got the false wall thing, too, and have the entire cavity lined with 2" of J-M Linacoustic. And I've got all of the first reflection points (to audience) covered with panels of 2" OC SelectSound Black. I have two problems. First, I have a VERY flabby 100Hz - 300Hz range. It's a real mess in fact. Why? My 2" does diddly at those frequencies. And my second problem is that the room has no "air" - the highs are being absorbed. Oh, I forgot to mention that I've got inexpensive carpet partially up the walls and that contributes to the too dead problem. The fix is to add diffusion.


Really, IMO, you won't be happy using only 1" anywhere. If it's cheaper to do double 1" to get the 2" then go for it. If not, get the 2". As for bass traps, I'm not sure that doubling 2" achieves the same result as real 4" stuff.


----------



## myfipie

>As for bass traps, I'm not sure that doubling 2" achieves the same result as real 4" stuff.


----------



## Ethan Winer

Pepar,


> I have questions; what's the best way to communicate?


----------



## Penniman

Glen, I feel cooler already!


For some reason the 2" material was $1.05 per square foot while the 1" was $0.45. I went with the 1". I bought extra so I can experiment with corner traps.


Thanks all!


Kip


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Pepar,
> 
> 
> > I have questions; what's the best way to communicate?


----------



## Ethan Winer

> You did. And I did.


----------



## myfipie

>Whew, I thought it my early Alzheimer's kicking in.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Cold-rolled steel?



CRS = Can't Remember ****



In it's advanced stages it becomes a far more serious condition known as CRAFT.

Can't Remember A Flipping (not allowed to use that "other" word, ya know) Thing


----------



## Meddy

A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.


Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet


----------



## pepar




> Quote:
> Originally Posted by *Meddy* /forum/post/0
> 
> 
> A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.
> 
> 
> Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet



Not a pro, but evidently the first to see your question, so I'll take a run at it. I think the answer may rest almost entirely on just what kind of insulation it is. Fiberglass, foam?


----------



## Meddy

Sorry, I should have mentioned it's pink fiberglass and if memory serves me correctly, as I'm not at home, it's only R-8.


----------



## pepar




> Quote:
> Originally Posted by *Meddy* /forum/post/0
> 
> 
> A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.
> 
> 
> Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet



And perhaps you could post a cross-sectional diagram of your wall construction from the concrete in?


----------



## pepar




> Quote:
> Originally Posted by *Meddy* /forum/post/0
> 
> 
> Sorry, I should have mentioned it's pink fiberglass and if memory serves me correctly, as I'm not at home, it's only R-8.



Without seing a diagram of the entire construction, I'll say that the pink fluffy stuff doesn't have much absorption at low bass frequencies, especially at 2" thick.


----------



## pepar




> Quote:
> Originally Posted by *Meddy* /forum/post/0
> 
> 
> A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.
> 
> 
> Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet



'Ere ya go - absorption coefficients of various insulations . .


----------



## myfipie




> Quote:
> Originally Posted by *Meddy* /forum/post/0
> 
> 
> Sorry, I should have mentioned it's pink fiberglass and if memory serves me correctly, as I'm not at home, it's only R-8.



It is not doing much for you.. You will still need to put bass trapping within the room..


Glenn


----------



## BasementBob

Meddy:


If you have an exposed concrete foundation wall, then having insulation go 4' below the outside earth, covered by vapor barior is fine.

If you put a wall in front of the concrete wall, then you should insulate right to the floor, including vapor barier right to the floor.


Walls (drywall) reflect a lot of sound. Think of walls as reflectors, more than as absorbers.


With drywall in front of the fiberglass, the fiberglass stops being an in-the-room absorber. It damps the resonance of the wall, so it's a good thing, but I wouldn't think of the fiberglass in the wall cavity as being an in-the-room-absorber, because the drywall is stopping a significant % of the sound energy from getting to the fiberglass (drywall reflects sound into the room). Nor would I think of the fiberglass in the wall cavity as being a bass trap.


----------



## clarkeven

After reading lots and lots about sound isolation.... I think I have an idea of what to do. As with most people I want to keep this as inexpensive as possible. So details...

My room is 14 x 19 with duct work going right down the middle of the room with about a foot in between the duct work. That brings the ceiling height down to around 7 feet in spots. My biggest concern is the duct work since I can't move it I have to deal with it. I was planning on wrapping the duct work with something... not sure yet. After that put R-19 insulation then a layer of MLV then double dry wall with green glue.


Does that sound like a good plan? Or is that a bit of over kill?


The walls I was just going to do R-19 and double dry wall with green glue.


The kitchen is right above where the movie theater will be...


I know there is so much to sound isolation, and I can't do it all... but this is the way I was planning on going. I found the MLV on a site that will cover the ceiling for around $300.00 this is the cheapest I have found anywhere. It is only the 1lbs per square inch. The green glue will run me around $400 for the entire room. That just leaves the dry wall and R-19 insulation.


So any of the guru's out there... could you let me know if this would be a waist?


Thank you in advance..


----------



## Joel DuBay




> Quote:
> Originally Posted by *clarkeven* /forum/post/0
> 
> 
> After reading lots and lots about sound isolation.... I think I have an idea of what to do. As with most people I want to keep this as inexpensive as possible. So details...
> 
> My room is 14 x 19 with duct work going right down the middle of the room with about a foot in between the duct work. That brings the ceiling height down to around 7 feet in spots. My biggest concern is the duct work since I can't move it I have to deal with it. I was planning on wrapping the duct work with something... not sure yet. After that put R-19 insulation then a layer of MLV then double dry wall with green glue.
> 
> 
> Does that sound like a good plan? Or is that a bit of over kill?
> 
> 
> The walls I was just going to do R-19 and double dry wall with green glue.
> 
> 
> The kitchen is right above where the movie theater will be...
> 
> 
> I know there is so much to sound isolation, and I can't do it all... but this is the way I was planning on going. I found the MLV on a site that will cover the ceiling for around $300.00 this is the cheapest I have found anywhere. It is only the 1lbs per square inch. The green glue will run me around $400 for the entire room. That just leaves the dry wall and R-19 insulation.
> 
> 
> So any of the guru's out there... could you let me know if this would be a waist?
> 
> 
> Thank you in advance..




As I read it, this does not sound too overkill. Indeed the Green Glue is a good choice if I understand its intended application here. And, as always, you will save money with a DIY approach. From reading this, I assume the duct work is running from your screen wall, to the back of your seating, not acros your seating from left to right, correct?

This is a mite bit better than the other way around I believe, as ceiling acoustic treatments (if you have a hard floor), may be easier to install and may yield a better overall sonic field. I am certain you know this, but you will require bass trapping if you currently do not have any. It is worth repeating this for anyone not familiar with basic acoustic treatment of a critical listening environment.


It sounds like you might be a bit "handy" and I think you'll have an easy go of this.


Good luck as always!


----------



## myfipie




> Quote:
> Originally Posted by *clarkeven* /forum/post/0
> 
> 
> After reading lots and lots about sound isolation.... I think I have an idea of what to do. As with most people I want to keep this as inexpensive as possible. So details...
> 
> My room is 14 x 19 with duct work going right down the middle of the room with about a foot in between the duct work. That brings the ceiling height down to around 7 feet in spots. My biggest concern is the duct work since I can't move it I have to deal with it. I was planning on wrapping the duct work with something... not sure yet. After that put R-19 insulation then a layer of MLV then double dry wall with green glue.
> 
> 
> Does that sound like a good plan? Or is that a bit of over kill?
> 
> 
> The walls I was just going to do R-19 and double dry wall with green glue.
> 
> 
> The kitchen is right above where the movie theater will be...
> 
> 
> I know there is so much to sound isolation, and I can't do it all... but this is the way I was planning on going. I found the MLV on a site that will cover the ceiling for around $300.00 this is the cheapest I have found anywhere. It is only the 1lbs per square inch. The green glue will run me around $400 for the entire room. That just leaves the dry wall and R-19 insulation.
> 
> 
> So any of the guru's out there... could you let me know if this would be a waist?
> 
> 
> Thank you in advance..




Just keep in mind that if you ever get a leak in the kitchen then you are in for a lot of repair..







Is sounding proofing that important to you? If so then you should be fine..


Glenn


----------



## clarkeven

Thank you for your reply's. I do realize I will need bass trappings and have planned it as part of my install along with covering the first reflection points with pannels and adding some more pannels along the wall for looks and more sound dispersion/absorbsion. I know I should probably do the whole Linacoustic just above ear level and GOM and the rest. But for me putting up the pannels will work just fine. I was going to put bass traps in the front two corners and maybe in the back as well. But I was going to wait and see how well everything sounded before I did that, I was planning on putting up some shelving on the back wall. Along with my Equipment rack.


Thanks again.


----------



## myfipie

Just take it slow.. No need to throw 12 bass traps in your room when 8 could have done the trick.. Take a look at Ryan's (member here) case study he did on adding room treatment.. He started with 4 then went to 8..


Glenn


----------



## Kevin12586

WOW, I can't believe I read through all 36 pages. It took me a few weeks reading a few pages a day, but I did it, and I am GLAD I did, I am definitely much more knowledgeable (at least I hope I am) then when I started.


One thing that I read a few days ago, that I hadn't realized is that I need to do the 'mirror' method for the center channel as well as the front left and right speakers. Because of this, it is possible to have 3 first reflection panels per seat, is this correct?


If I place the 2x4 panels horizontally, is that a 'bad' thing? One advantage is that one panel, 4 feet across, may be able to hit more than one reflection point.


Be warned, I will have a few more questions/clarifications as I get closer to building my panels, but I figured I would start with the easy questions.


----------



## Stima




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> One thing that I read a fes days ago, that I hadn't realized is that I need to do the 'mirror' method for the center channel as well as the front left and right speakers. Because of this, it is possible to have 3 first reflection panels per seat, is this correct?



Yep...3 points per speaker per wall, ceiling and floor.


As far as using the panels horizontally....no problem there. The sound waves don't care...so you shouldn't either.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> WOW, I can't believe I read through all 36 pages. It took me a few weeks reading a few pages a day, but I did it, and I am GLAD I did, I am definitely much more knowledgeable (at least I hope I am) then when I started.
> 
> 
> One thing that I read a few days ago, that I hadn't realized is that I need to do the 'mirror' method for the center channel as well as the front left and right speakers. Because of this, it is possible to have 3 first reflection panels per seat, is this correct?
> 
> 
> If I place the 2x4 panels horizontally, is that a 'bad' thing? One advantage is that one panel, 4 feet across, may be able to hit more than one reflection point.
> 
> 
> Be warned, I will have a few more questions/clarifications as I get closer to building my panels, but I figured I would start with the easy questions.



Do not overlook the REAR wall. When adding my panels - check my link - I happened to add the rear one first and was blown away by the improvement in clarity and imaging of the FRONT speakers. Much improved main/surround integration as well. Next added were the front sides - I already had a rug in room front with the thickest padding I could find - which further improved clarity, imaging and surround integration. Last added was the front ceiling panel which added even more improvement in the same areas. I now have nearfield listening at my second row.


Unless you have a very small room, 2' x 4' panels may not do it. You really need to visualize incidence/reflection from all front speakers to all seats. My front side panels are 4' x 4', ceiling 4' x 8' and rear is 2' x 8'.


Have fun!


----------



## bpape

And if you have 2 rows of 4 seats, you'll have 8 points per speaker per wall.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> And if you have 2 rows of 4 seats, you'll have 8 points per speaker per wall.



If you do it right, you can "cover" all points from all speakers to all seats with one panel per surface.


----------



## Kevin12586

I am going to have 5 seats and found that I can use 3 panels for the front speakers reflection points, now I need to figure out the center. Maybe I will get lucky and some of those points will fall on the same panels.


----------



## bpape

Pepar.


That all depends on how far the speakers are from each other, how far from the walls, how far apart the rows are, etc. I could show you plottings in 18'-20' long rooms with 2 rows and speakers behind a false wall where the distance from the first point to the last point on the wall is almost 10' apart.


Now, if you want 1 big 8-10' long panel in your room on each wall, I'm sure you could cover them in most rooms with 1 panel







Personally, if I'm going to see the panels and not have them hidden behind a cloth facade, I try to put up something that is visually interesting instead of just a monolith. Just a matter of personal taste.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> That all depends on how far the speakers are from each other, how far from the walls, how far apart the rows are, etc. I could show you plottings in 18'-20' long rooms with 2 rows and speakers behind a false wall where the distance from the first point to the last point on the wall is almost 10' apart.



Yes, of course. My suggestion falls apart in large rooms.


----------



## bpape

Oh, you'll still find 'groupings' of points even in larger rooms. Many times you'll find points for 1 seat in the front row and 1 seat in the back row that have almost identical points. You can still do multiple points with a single panel. Sometimes you get lucky and everything falls right and you can cover all the points with 3 - 2' wide panels - sometimes not.


This is one of the reasons that working behind a cloth covered wall is nice. You can put up panels where they're needed or even do something solid without worrying about what it looks like, is it symmetric between 2 columns, etc.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Oh, you'll still find 'groupings' of points even in larger rooms. Many times you'll find points for 1 seat in the front row and 1 seat in the back row that have almost identical points. You can still do multiple points with a single panel. Sometimes you get lucky and everything falls right and you can cover all the points with 3 - 2' wide panels - sometimes not.
> 
> 
> This is one of the reasons that working behind a cloth covered wall is nice. You can put up panels where they're needed or even do something solid without worrying about what it looks like, is it symmetric between 2 columns, etc.



Are you using false walls all around?!


----------



## Kevin12586

Along my basement walls I have a chair rail, and of course it is located horizontally exactly where the panels need to be mounted. Other than removing the chair rail wherever I place the panels, which would be a last resort, does anyone have any ideas of something I can put behind the panels so that when mounted over the chair rail it can remain level and perform its intended purpose?


----------



## Stima




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Along my basement walls I have a chair rail, and of course it is located horizontally exactly where the panels need to be mounted. Other than removing the chair rail wherever I place the panels, which would be a last resort, does anyone have any ideas of something I can put behind the panels so that when mounted over the chair rail it can remain level and perform its intended purpose?




I wouldn't go through all that trouble. Just make your panesl stop 4" above and below the chair rail. As long as the rail isn't perfectly at ear height, I would say the gap in the panels would cause minimal effect to the absorbtion.


----------



## bpape

Pepar.


I'm talking about when you use a track system or just firring strips to space the cloth out from the drywall by an inch or 2.


----------



## Kevin12586




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> I wouldn't go through all that trouble. Just make your panesl stop 4" above and below the chair rail. As long as the rail isn't perfectly at ear height, I would say the gap in the panels would cause minimal effect to the absorbtion.



That is the problem, the chair rail is at ear height when seated upright and just above when reclined.


----------



## Stima

Then perhaps you could make the panels appear to "float" off the wall over the chair rail by making your panels stand off a few inches from the wall??


Spacing panels off the wall actually HELPS in absorption so don't be worried about the acoustics if you float the panels.


----------



## Kevin12586

What could I mount behind the panels to make them float over the chair rail?


----------



## 1kevinm

You could try using pvc pipe cut to the appropriate length. There is even some that is already grey or black that is used for irragation system risers, it is probably around 1.25" od. Depending on how your panels are made they may just rest in the corners, or drill a hole across the diameter and screw them in, or you could even use hot melt glue to glue them to a wood frame.


Of course, you could also just use some pieces of wood in the same way.


Just a few thougths for some simple solutions, I'm sure there are many other ways also.


Kevin


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> What could I mount behind the panels to make them float over the chair rail?



You could stand them off - mount them on stand-offs - that clear the rail . . . wood blocks, metal blocks or even genuine stand-offs - metal sleeves that slip over screws. Or, if you are building the panels, scribe and cut the rail profile out of the frame members where they hit the rail. The fiberglass inside would esaily mold itself to the rail. The panel would be flat against the wall and the rail will continue under - through actually - the panel and out the other side. The scribing/cutting would, IMO, produce the most elegant result.


----------



## Kevin12586

Thanks for the suggestions guys. I don't plan to put a frame around my panels, so I will look into either the pvc (in black), stand offs or wood.


Any other ideas?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Thanks for the suggestions guys. I don't plan to put a frame around my panels, so I will look into either the pvc (in black), stand offs or wood.
> 
> 
> Any other ideas?



How will you cover the fiberglass bats and then mount them without a frame? They do not have enough rigidity, in my experience, without a frame.


----------



## Kevin12586

From reading through this thread, and seeing pictures of others that have mounted theirs, I was just planning to wrap them in fabric and use screws with washers and mount them. That is what I have seen and read others have done.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> From reading through this thread, and seeing pictures of others that have mounted theirs, I was just planning to wrap them in fabric and use screws with washers and mount them. That is what I have seen and read others have done.



10-4. I've heard of that as well. It seems to yield less of a "finished" look, but that's a matter of preference. Here's some specialized hardware to do just that -

Here 


and here .


----------



## dknightd




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Thanks for the suggestions guys. I don't plan to put a frame around my panels, so I will look into either the pvc (in black), stand offs or wood.
> 
> 
> Any other ideas?



I'd just put some more rigid fiberglass behind them to fill in the gap above the chair rail.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> 10-4. I've heard of that as well. It seems to yield less of a "finished" look, but that's a matter of preference. Here's some specialized hardware to do just that -



Or, for compressed panels, here: http://www.rotofast.com/home.htm 


Really neat.


Kal


----------



## stromand




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> Or, for compressed panels, here: http://www.rotofast.com/home.htm
> 
> 
> Really neat.
> 
> 
> Kal



Kal, Have you used these? They really look simple and effective. Is there a on-line retail source you used? I was considering a french cleat installation but this looks much better.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *stromand* /forum/post/0
> 
> 
> Kal, Have you used these? They really look simple and effective. Is there a on-line retail source you used? I was considering a french cleat installation but this looks much better.



Used them this weekend for the first time and I am sold. Got them as samples but you should ask at the website.


Kal


----------



## jandawil




> Quote:
> Originally Posted by *stromand* /forum/post/0
> 
> 
> Kal, Have you used these? They really look simple and effective. Is there a on-line retail source you used? I was considering a french cleat installation but this looks much better.



I looked at their site and they are .89 each. So at 4/panel cost is $3.50 each panel for hangers. I plan on about 15 panels so that is $52.50 for hangers. Sounds a little pricy, but I have not compared alternatives. I was considering these speaker grill guides from Parts Express. They are only 1.45 for a kit of 12 and they would work well if you have any sort of wood frame around your panel like a lot of people do. Just not sure how well they would work with hanging on drywall though...


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/0
> 
> 
> I looked at their site and they are .89 each. So at 4/panel cost is $3.50 each panel for hangers. I plan on about 15 panels so that is $52.50 for hangers. Sounds a little pricy, but I have not compared alternatives. I was considering these speaker grill guides from Parts Express. They are only 1.45 for a kit of 12 and they would work well if you have any sort of wood frame around your panel like a lot of people do. Just not sure how well they would work with hanging on drywall though...



From the looks of those grill guides, they pre-suppose being mounted to a frame. Absent a frame, somehing will need to be driven through an "un-structured" fibelglass panel to have any chance of holding it.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> From the looks of those grill guides, they pre-suppose being mounted to a frame. Absent a frame, somehing will need to be driven through an "un-structured" fibelglass panel to have any chance of holding it.



Agreed. Also, I am not sure that you wouldn't need more than four per panel if you wanted to sit beneath them.










In addition, the Rotofasts are really easy to set up, align and mount in minutes.


Kal


----------



## stromand




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> Used them this weekend for the first time and I am sold. Got them as samples but you should ask at the website.
> 
> 
> Kal



I just send a request for information to Rotafast. I like these better than the grill guides since they mount directly to the material versus having to fabricate wood frames.


----------



## Kevin12586




> Quote:
> Originally Posted by *dknightd* /forum/post/0
> 
> 
> I'd just put some more rigid fiberglass behind them to fill in the gap above the chair rail.



From everything that I have read, you want to have either 1" or 2" rigid fiberglass, if I used more fiberglass behind them, that would make them too thick for their purpose.


I se all the different suggestions for how to hang the panels above, but is there anything wrong with just using screws and washers or is it more for the appearance?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> From everything that I have read, you want to have either 1" or 2" rigid fiberglass, if I used more fiberglass behind them, that would make them too thick for their purpose.
> 
> 
> I se all the different suggestions for how to hang the panels above, but is there anything wrong with just using screws and washers or is it more for the appearance?



Oh no, there is no such thing as "too thick" for their purpose, at least not from a purely performance standpoint. (An SO may have other "issues" though.) In fact, if you use 2" like I did you will probably find yourself - like I did - going back and adding bass traps. Two inch of fiberglass - I used OC SelectSound black - will NOT reach effectively to mid- and upper-bass frequencies. And doesn't come close to deep bass. If I had had the room - and the understanding I have now - I would have used *four inches* of 'glass. I would still need to go back and add some bass traps, but my room wouldn't be such a mess 100Hz - 300Hz.


And 1" is useless for first-reflection-point control.


----------



## jandawil

I do like the idea of not building frames. I just want these things done!! Where is everyone getting their rigid fiberglass???


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/0
> 
> 
> I do like the idea of not building frames. I just want these things done!! Where is everyone getting their rigid fiberglass???



I looked for and fouind a local "insulation distributor" for Owens Corning. I am about to contact them again for 4" 703 for bass traps. There's alot of things I'd rather not do, but no frames was not even considered. I did not build a Rialto, but aesthetics mean something. Frames allowed me to tightly stretch GOM and have a very finished look. Mounting on the wall and CEILING was a breeze with frames.


YMMV.


Check the link in my sig for what I did.


----------



## stromand




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Oh no, there is no such thing as "too thick" for their purpose, at least not from a purely performance standpoint. (An SO may have other "issues" though.) In fact, if you use 2" like I did you will probably find yourself - like I did - going back and adding bass traps. Two inch of fiberglass - I used OC SelectSound black - will NOT reach effectively to mid- and upper-bass frequencies. And doesn't come close to deep bass. If I had had the room - and the understanding I have now - I would have used *four inches* of 'glass. I would still need to go back and add some bass traps, but my room wouldn't be such a mess 100Hz - 300Hz.
> 
> 
> And 1" is useless, even for first-reflection-point control.



I do not understand this at all. I have seen, more than once, the bonafide experts like Dennis Erskine state that 1" on the walls at ear level and below is sufficient for most home theaters. More than this will cause the room to be too dead. From what I understand, you are not trying to trap much base on the walls that is what room boundaries like in the corners are for.


Pepar, sounds like you need one of these acoustic engineers to bring their equipment in, test your room, and make specific recommendations.


----------



## pepar




> Quote:
> Originally Posted by *stromand* /forum/post/0
> 
> 
> I do not understand this at all. I have seen, more than once, the bonafide experts like Dennis Erskine state that 1" on the walls at ear level and below is sufficient for most home theaters. More than this will cause the room to be too dead. From what I understand, you are not trying to trap much base on the walls that is what room boundaries like in the corners are for.
> 
> 
> Pepar, sounds like you need one of these acoustic engineers to bring their equipment in, test your room, and make specific recommendations.



I've not seen anything re 1" being sufficient for first reflection points. As for a room being made too dead, that's a function of the percent of room surface area covered with absorptive material. If only the "first reflection" points are being covered, I can't see how that'd be enough to make it too dead - 1", 2" or 4". Why would you cover all of the walls at and below ear level? That most likely would deaden the room too much (even if you only used carpet).


Are you talking about the entire room at and below ear level, or only first reflection points?


----------



## Terry Montlick




> Quote:
> Originally Posted by *stromand* /forum/post/0
> 
> 
> I do not understand this at all. I have seen, more than once, the bonafide experts like Dennis Erskine state that 1" on the walls at ear level and below is sufficient for most home theaters.



A 1" thickness of fiberglass is sufficient to control early reflections. These cause imaging problems at medium to high frequencies, and the lower frequency absorption of thicker fiberglass is unnecessary.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> A 1" thickness of fiberglass is sufficient to control early reflections. These cause imaging problems at medium to high frequencies, and the lower frequency absorption of thicker fiberglass is unnecessary.
> 
> 
> - Terry



Bingo! Thanks, I've been enlightened. I thought reaching lower was a benefit with the corollary being 1" was insufficient.


----------



## bpape

Nope. 1" is plenty - if all you need from those panels is reflection control. If you need additional overall control in lower frequencies, then 2" or more is certainly not going to hurt anything.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Nope. 1" is plenty - if all you need from those panels is reflection control. If you need additional overall control in lower frequencies, then 2" or more is certainly not going to hurt anything.



I guess that was my point/question; if you've got the physical space, why not apply 2" as you will most likely need to control lower frequencies anyway?


----------



## myfipie

I am with you on that pepar... Most rooms need as much low end absorption as it can get.. Not saying bryan or Terry is wrong..

Glenn


----------



## bpape

I was just agreeing with Terry that 1" is sufficient IF all you need is reflection control. In a small room where you don't have a lot of space, sometimes the reflection panels need to do double duty.


If you're already addressed the bottom end in other ways and don't need it or there are corners free where it's more effective, then 1" would be sufficient.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> I was just agreeing with Terry that 1" is sufficient IF all you need is reflection control. In a small room where you don't have a lot of space, sometimes the reflection panels need to do double duty.
> 
> 
> If you're already addressed the bottom end in other ways and don't need it or there are corners free where it's more effective, then 1" would be sufficient.



If I've learned anything in building my own home theater, and that's always debatable, it's that a holistic approach must be employed for acoustical treatments. Knowing a little - or even a lot - about one aspect doesn't cut it. Sooo, for every true statement - 1" is sufficient for first reflection control - there are two (or more) "ifs" that may not be obvious unless you have a broad understanding of the whole - a big part of the fact that people make a living at acoustics.


----------



## myfipie

Bryan, I think you and I are saying the same thing here.. Most rooms can not fit enough bass trapping in it anyway, so the 2" panels can help with the rest..

Glenn


----------



## Kevin12586

Now I am unsure again if I am supposed to use 1" or 2" panels for my first reflection points. My basement is over 6000 cubic feet, with about 1/3 of that for the actual theater. The theater itself is open to the entire basement and my plan is to put either 1" or 2" panels at my FRP and 4" thick base trapping at all corners and soffits, a total of 13 corners.


Based on this, should I stick with the 1" or go with 2" for my FRP?


----------



## bpape

For a room that large, just off the top of my head, I'd probably use 2".


----------



## myfipie

sorry double post


----------



## myfipie

Would that be 13 bass traps or 13 panels all together?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Now I am unsure again if I am supposed to use 1" or 2" panels for my first reflection points. My basement is over 6000 cubic feet, with about 1/3 of that for the actual theater. The theater itself is open to the entire basement and my plan is to put either 1" or 2" panels at my FRP and 4" thick base trapping at all corners and soffits, a total of 13 corners.
> 
> 
> Based on this, should I stick with the 1" or go with 2" for my FRP?



Is this not a rectangle? The 13 corners thing makes me ask.


----------



## Kevin12586

It is 13 bass traps, not including the FRP.


Please see the attachment for a layout of my basement. It isn't a perfect square, far from it, but the reason that I have 13 corners is because I am also including the corner created with the soffits and the ceiling.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> It is 13 bass traps, not including the FRP.
> 
> 
> Please see the attachment for a layout of my basement. It isn't a perfect square, far from it, but the reason that I have 13 corners is because I am also including the corner created with the soffits and the ceiling.



Just a comment, Kevin12586. The sound coming from the front left speaker will probably sound very different from the right front speaker due to the left's proximity to the wall. Hopefully, someone more knowledgable will chime in, but I don't think any amount of sound treatment will change that. Not able to locate your theater in the "lower left" corner of the diagram facing "west?"


----------



## Kevin12586

Pepar, I haven't noticed a difference in sound between the 2 fronts (the left is actually about 6-9" off the wall), but I am no expert so maybe that is the case. Because of my screen, I can't move the speaker any further away from the wall but I am happy with the sound I get now. Currently I don't have a center speaker so the 2 fronts are setup as a phantom center and I don't notice a difference when something panes across the front sound stage. Based on what I have read, if I am happy now I will be ecstatic once I get my basement treated.


The basement is a multi function area, the theater is in the top portion of the drawing where you see the screen and speakers, the rest is used for other things. Because everything is open, that is why I am planning on so many base traps.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Pepar, I haven't noticed a difference in sound between the 2 fronts (the left is actually about 6-9" off the wall), but I am no expert so maybe that is the case. Because of my screen, I can't move the speaker any further away from the wall but I am happy with the sound I get now. Currently I don't have a center speaker so the 2 fronts are setup as a phantom center and I don't notice a difference when something panes across the front sound stage. Based on what I have read, if I am happy now I will be ecstatic once I get my basement treated.
> 
> 
> The basement is a multi function area, the theater is in the top portion of the drawing where you see the screen and speakers, the rest is used for other things. Because everything is open, that is why I am planning on so many base traps.



Yeah, I tend to be fixated on symetricality, but if you hear no difference, that's the bottom line. And you *will* be a very happy camper with acoustical treatments added. I'd definitely go for 2" on the wall with the close speaker, and elsewhere as well. You will notice a big improvement in imaging, left-to-right, and probably front-to-back (depth) as well. One more thing; the FRONT wall is a FRP. And since it it the closest to the speakers, it produces the closest reflection temporally speaking. The "speaker wall" and the back wall tend to get overlooked.


----------



## Kevin12586

With the front wall, I plan to put some 2" panels behind my screen and both on top and to the right of it. To the left of it will have a bass trap that will come up right next to the screen.


Since reading this thread I have noticed that I don't 'notice' the pans from left to right or front to back as much as I feel I should. I can't wait to get started to experience more of my system.


----------



## myfipie

Let us know how it comes out.. Glad to hear you are going with the 2" panels.. I think it is better to be safe then sorry!!


Glenn


----------



## Westshorestudios

I understand that sound moves in waves and that virtually all materials, whether sheet rock, rigid fiberglass, mineral wool, plywood, people, etc. absorb some, reflect some and transmit through the material some of those sound waves.


My question is, how do the materials being hit with the sound waves "know" which to reflect and which to absorb? (I know that don't "know" anything, but go with me on this, ok?).


For example, my risers are over a sunken concrete sub floor. The risers are 18" deep and 9" deep. I have blown in cellulose under those risers (about 15" deep and 8" deep, respectively). The risers are topped with 2 layers of 3/4" plywood, separated by roofing felt. The plywood is covered with carpet pad and carpet. The plywood floor should absorb some and transmit some and reflect some of the waves, right? (Maybe to simplify this we should focus on low to medium waves, because I assume that at some mid to high frequency range, the plywood is going to reflect all of the wave).


If the frequency is long enough / low enough to penetrate the carpet / pad / plywood / felt / plywood floor, shouldn't it all be absorbed either going through the cellusose (going down) or if not, then absorbed when it bounces offf the concrete sub floor and travels back through the cellulose going up, or hitting the plywood riser floor, etc.? Seems like I wouldn't need bass trapping in corners, etc.?


Another example: the walls. Higher frequencies are going to be reflected off the sheet rock walls and stay in the room. Lower frequencies will penetrate the walls to the other rooms but some will also be reflected around in the room, right? Why do some penetrate and some stay in the room? If low bass is penetrating the walls, why do we need bass trapping in the room?


Confused in Dallas


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Since reading this thread I have noticed that I don't 'notice' the pans from left to right or front to back as much as I feel I should. I can't wait to get started to experience more of my system.



With a completely untreated room, all of the first reflections are at their max. And there is generally nothing to attenuate the reverberance - where all the reflections "merge" to become one big mess. The early reflections (from the FRPs) confuse the brain, robbing the original sound of its clarity and all the subtleties that give us width and depth. In this context, I mean "depth" as part of the FRONT soundstage, not front-to-back pans. Good acoustical treatments will intergrate the surrounds with the front speakers, too, but I mean being able to hear that one person speaking - or singing - is behind a second.


I remember the first time I distinctly heard that. It was the first time I heard a 5.1 DD system and Indiana Jones/lLast Crusade with Harrison Ford and Sean Connery in the front seats of the car and John Rhys-Davies in the back. A sentence or two were exchanged between Ford and Connery and then Rhys-Davies chimed in. Oh - my - god, I thought. And when Rhys-Davies leaned forward and joined the conversation, that was conveyed in the soundtrack as well.


The more you can reduce the early reflections and, to a certain extent, the reverberance, the more the sountrack - or album - will . . take you away. And when it ALL comes together, the A/V gear will disappear and it'll be you and the movie/album. Sorry to sound like an evangelist.


----------



## myfipie




> Quote:
> Originally Posted by *Westshorestudios* /forum/post/0
> 
> 
> I understand that sound moves in waves and that virtually all materials, whether sheet rock, rigid fiberglass, mineral wool, plywood, people, etc. absorb some, reflect some and transmit through the material some of those sound waves.
> 
> 
> My question is, how do the materials being hit with the sound waves "know" which to reflect and which to absorb? (I know that don't "know" anything, but go with me on this, ok?).
> 
> 
> For example, my risers are over a sunken concrete sub floor. The risers are 18" deep and 9" deep. I have blown in cellulose under those risers (about 15" deep and 8" deep, respectively). The risers are topped with 2 layers of 3/4" plywood, separated by roofing felt. The plywood is covered with carpet pad and carpet. The plywood floor should absorb some and transmit some and reflect some of the waves, right? (Maybe to simplify this we should focus on low to medium waves, because I assume that at some mid to high frequency range, the plywood is going to reflect all of the wave).
> 
> 
> If the frequency is long enough / low enough to penetrate the carpet / pad / plywood / felt / plywood floor, shouldn't it all be absorbed either going through the cellusose (going down) or if not, then absorbed when it bounces offf the concrete sub floor and travels back through the cellulose going up, or hitting the plywood riser floor, etc.? Seems like I wouldn't need bass trapping in corners, etc.?
> 
> 
> Another example: the walls. Higher frequencies are going to be reflected off the sheet rock walls and stay in the room. Lower frequencies will penetrate the walls to the other rooms but some will also be reflected around in the room, right? Why do some penetrate and some stay in the room? If low bass is penetrating the walls, why do we need bass trapping in the room?
> 
> 
> Confused in Dallas



that is a very big question you asked and to really understand it I would recommend reading the Master handbook of Acoustics.

Just a couple comments,

Yes when you have dry wall SOME of the low end will go through the wall but not all of the sound. So you need bass traps to help with that.. Now if you have concrete walls then most of the LF sound is staying in the room, so you are going to need even more bass traps to help with the sound.. The first question I ask people is dry wall or contrate..

As far as your riser that is only going to absorb HF because it is a thin material.. Sound absorbtion is achieved from Density of material and thickness..


Hope that helps answer some of what you are wondering..


Glenn


----------



## sdspga

I've been lurking this thread for a few weeks and want to thank all of you for your insight. BTW, great job on your panels, Pepar. I made mine in almost the same way using the same materials. HUGE improvement in the sound quality of my room.


I had a question about Kevin's last quote:



> Quote:
> With the front wall, I plan to put some 2" panels behind my screen and both on top and to the right of it.



Does it make a big difference to put treatments behind the screen if the screen is not accoustically transparent? I thought that the screen itself reflects the sound. again, many thanks,


scott


----------



## pepar




> Quote:
> Originally Posted by *sdspga* /forum/post/0
> 
> 
> Does it make a big difference to put treatments behind the screen if the screen is not accoustically transparent? I thought that the screen itself reflects the sound.



The screen is more "acoustically transparent" than you think. For the purposes of placing a center speaker behind, it is not, but still a lot of sound goes through it. And lower frequencies go around it like a wave going around a small rock.


----------



## pepar




> Quote:
> Originally Posted by *sdspga* /forum/post/0
> 
> 
> I've been lurking this thread for a few weeks and want to thank all of you for your insight. BTW, great job on your panels, Pepar. I made mine in almost the same way using the same materials. HUGE improvement in the sound quality of my room.



Thanks, and 10-4 on the HUGE improvement. I am now working on designing, building and installing bass traps. Pictures of the whole process to follow.


----------



## sdspga

thanks, I did not realize that. makes sense on the lower end, though. If the lower frequencies are penetrating my drywall, the screen shouldn't offer much resistance.


----------



## ciotime

Im also in the process of building a dedicated home theater room. The room is 14'x21' with an 8 foot ceiling. I know about placing absorber panels to treat the 1st reflection points but what else do I do with the remaining side walls? Leave them reflective? I keep reading about bass traps placed in corners. You mean the corners on the side and front walls? Or just the side wall thats nearest to the corners?


----------



## pepar




> Quote:
> Originally Posted by *ciotime* /forum/post/0
> 
> 
> Im also in the process of building a dedicated home theater room. The room is 14'x21' with an 8 foot ceiling. I know about placing absorber panels to treat the 1st reflection points but what else do I do with the remaining side walls? Leave them reflective? I keep reading about bass traps placed in corners. You mean the corners on the side and front walls? Or just the side wall thats nearest to the corners?



Ideally, the corner formed by two walls and the ceiling (or floor, if possible). Ceiling/wall (one of them) corners come next.


----------



## myfipie




> Quote:
> Originally Posted by *ciotime* /forum/post/0
> 
> 
> Im also in the process of building a dedicated home theater room. The room is 14'x21' with an 8 foot ceiling. I know about placing absorber panels to treat the 1st reflection points but what else do I do with the remaining side walls? Leave them reflective? I keep reading about bass traps placed in corners. You mean the corners on the side and front walls? Or just the side wall thats nearest to the corners?



You want to hit as many corners as possible in your room.. Starting with the front two corners and working from there.. take a a look at a case study a member did on AVS..
http://www.sbrjournal.net/currentiss.../Acoustics.htm 

It really shows how bass traps work and the benefit you will get..


Glenn


----------



## ciotime

So what do I do with the rest of the side walls? Other than the absorbers do I just leave the other walls reflective or do I put panel traps?


----------



## MUCHO

I'm building some room treatments, and can't remember the name of that cloth that is popular to cover them in. Starts with an A? I remember seeing an inexpensive place to buy it on the web.


Also I have heard any cloth will do, so long as you can "blow through it" - right?


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> You want to hit as many corners as possible in your room.. Starting with the front two corners and working from there.. take a a look at a case study a member did on AVS..
> http://www.sbrjournal.net/currentiss.../Acoustics.htm
> 
> It really shows how bass traps work and the benefit you will get..
> 
> 
> Glenn



Ah, 45's and reel-to-reel . . .


----------



## pepar




> Quote:
> Originally Posted by *MUCHO* /forum/post/0
> 
> 
> I'm building some room treatments, and can't remember the name of that cloth that is popular to cover them in. Starts with an A? I remember seeing an inexpensive place to buy it on the web.
> 
> 
> Also I have heard any cloth will do, so long as you can "blow through it" - right?



Blow through it equally at all audible frequencies.


----------



## MUCHO




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Blow through it equally at all audible frequencies.



What do you reccomend?


----------



## pepar




> Quote:
> Originally Posted by *MUCHO* /forum/post/0
> 
> 
> What do you reccomend?



I used/use Guilford of Maine, referred to as "GOM". It is not cheap, and perhaps something of equal performance could be found, but it has been tested and they have a nice assortment of colors and textures. My thinking is that for the amount I need to use, it wasn't going to break the bank. I suggest you google "grille cloth" and do a LOT of reading.


Just my $.02.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Blow through it equally at all audible frequencies.



LOL










Fortunately, the DC blow-through test generally extends to high frequencies!










Regards,

Terry


----------



## ciotime

I'd like some advice on how to treat my HT room. The room is 14x21 with 8 foot celings. Right now its still bare cement walls. Im gonna be doing 2x4 studs with soft insulation in between then cover with drywall to add to isolation.Ive listed below different options for treatments so please advice me on which one should I use.


1) 2 4x8 mid/hi absorbers for the 1st reflection points on the side walls ( 1 panel on each side ) all remaining walls will be deep bass traps.


2) 2x2 deep bass panels for the upper and bottom part of the side walls from front to back. 2x4 mid/hi absorbers for the middle part of the wall also from front to back.


3) back wall is all mid/hi absorbers


4) BACK WALL in between the 2 rear surround speakers are mid/hi absorbers while the left and right side of the rear wall s

urround speakers are diffusers.


----------



## bpape

That should really go in your own thread.


----------



## bighoot

This is going to sound crazy but I saw in a friends house a ceiling covered in peg board. ( tHIS was done for some other reason than accoustics) and then covered in textured wall paper.It looked dam good considering. If it was painted flat black it may look great, and it was cheap. I was wondering how well this would work in my theater in place of drywall if the joist cavities where filled with insulation. and the holes in the peg board where for 1/4 in. hooks. I am clueless as to whether this would work or not. But I am temped to try it because like I said, It was very cheap. Maybe $100.00 for my room --- 12 x 20 x 7 (Dam low ceilings)


----------



## myfipie

Bighoot,


It would work better then drywall, but it is not going to let the HF absorb enough... I would not do it.. You are much better off putting a drop ceiling in..


Glenn


----------



## TumaraBaap

A Problem of Too Much Absorption



I'm planning on using 2" rigid fiberglass for 1st reflection points & flutter echo on the side, front, rear walls and ceiling. In addition I plan on 4" to 6" panels of the same in the corners for bass absorption. Room is 16 X 13 X 9. Too much fibergass for a fairly small room! My concern is making the room too dead. I looked at ASC tube traps, Studiopanel bazorbers & springtraps, mondo traps etc for bass absorption but prices are sobering to say the least. Any tricks to keep the room somewhat "alive"?


I'm thinking of having open back bookcase towers (interspersed with books) in front of corner fibergass panels to add to HF dispersion without too adversely affecting bass absorber performance. Will this work? In fact I understand this would actually assist mid-bass absorption.


Also, will it help going with a wood floor instead of wall to wall carpet? Of course with a wood floor I would have carpet pad plus area rug midway between listening seats and front loudspeakers.


I've ruled out using thinner fibergass panels... my understanding is thinner panels greatly reduce broadband range without affecting amount of absorption at most (mid to high) frequencies.


Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> A Problem of Too Much Absorption
> 
> 
> 
> I'm planning on using 2" rigid fiberglass for 1st reflection points & flutter echo on the side, front, rear walls and ceiling. In addition I plan on 4" to 6" panels of the same in the corners for bass absorption. Room is 16 X 13 X 9. Too much fibergass for a fairly small room! My concern is making the room too dead. I looked at ASC tube traps, Studiopanel bazorbers & springtraps, mondo traps etc for bass absorption but prices are sobering to say the least. Any tricks to keep the room somewhat "alive"?
> 
> 
> I'm thinking of having open back bookcase towers (interspersed with books) in front of corner fibergass panels to add to HF dispersion without too adversely affecting bass absorber performance. Will this work? In fact I understand this would actually assist mid-bass absorption.
> 
> 
> Also, will it help going with a wood floor instead of wall to wall carpet? Of course with a wood floor I would have carpet pad plus area rug midway between listening seats and front loudspeakers.
> 
> 
> I've ruled out using thinner fibergass panels... my understanding is thinner panels greatly reduce broadband range without affecting amount of absorption at most (mid to high) frequencies.
> 
> 
> Tumara Baap



Well, there's probably something more tuned to the room's problem bass area that wouldn't absorb too much high frequencies, but it may not be a DIY item and therefore much more expensive that the 'glass you mention. Based on what I've done so far, I'd do the first reflection points and then take some measurements before and after adding the bass traps, including RT60. (I'm sure the traps are needed.) If it's too dead, research diffusors.


Just my novice $.02.


----------



## HardDrive

First, the Setup:


My theater is in a basement alcove. LCR speakers hang from chains about 1 foot out from an untreated masonry wall. Surrounds are along the sidewalls, also untreated masonry. There is no back wall, it opens to the rest of the basement and is visually separated from the rest of the basement by a painting tarp, floor to ceiling. Room is roughly 15x15 or so. Floor is carpeted and there's a big couch that spans the width of the room. Ceiling is unfinished. I've heard this type of setup called "Live in front, dead in back."


The Sound:


Bass is good and deep, not too boomy, with the SVS subwoofer at the back of the room behind where the side walls end. My only complaint is that the sound gets rather harsh at loud volumes. I think this comes from reflections between the side walls, as the harshness does not depend on where you are in the room (first reflection issues would be location-specific, right?). I hear multiple echos when I clap my hands.


The Question:


I am planning wall treatments for the side walls. Given there are no reflections from the back of the room, do I need treatments on the front wall too? Also, would diffusors on the side walls do any good in my case? I could always do a layer of 703 as an absorber and put pyramid or egg-crate diffusors on top. Give it that post-modern recording studio look.










Thanks for any and all advice!


HDD


----------



## Dangeresque




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> A Problem of Too Much Absorption
> 
> 
> 
> I'm planning on using 2" rigid fiberglass for 1st reflection points & flutter echo on the side, front, rear walls and ceiling. In addition I plan on 4" to 6" panels of the same in the corners for bass absorption. Room is 16 X 13 X 9. Too much fibergass for a fairly small room! My concern is making the room too dead. I looked at ASC tube traps, Studiopanel bazorbers & springtraps, mondo traps etc for bass absorption but prices are sobering to say the least. Any tricks to keep the room somewhat "alive"?
> 
> 
> I'm thinking of having open back bookcase towers (interspersed with books) in front of corner fibergass panels to add to HF dispersion without too adversely affecting bass absorber performance. Will this work? In fact I understand this would actually assist mid-bass absorption.
> 
> 
> Also, will it help going with a wood floor instead of wall to wall carpet? Of course with a wood floor I would have carpet pad plus area rug midway between listening seats and front loudspeakers.
> 
> 
> I've ruled out using thinner fibergass panels... my understanding is thinner panels greatly reduce broadband range without affecting amount of absorption at most (mid to high) frequencies.
> 
> 
> Tumara Baap



Don't know if you know about some of the newer sound absorbing materials being used in the world of faux finishes.There's an all-natural material that I install that you can custom color and design, trowel on, and get a 20% sound absorption. What is nice is that you can put it on any surface (ceilings, doors, etc.), repair it if needed, and even strip it. The thickness is only about 1/8" too. So if you are worried about thickness I thought I'd mention this other alternative.


----------



## myfipie

>I am planning wall treatments for the side walls. Given there are no reflections from the back of the room, do I need treatments on the front wall too? Also, would diffusors on the side walls do any good in my case? I could always do a layer of 703 as an absorber and put pyramid or egg-crate diffusors on top. Give it that post-modern recording studio look.


----------



## HardDrive

Thanks for the treatment advice. As for the bass, I have done a very simple set of tests. I burned a bunch of test tones onto a CD and measured each with my Radioshack meter. No glaring peaks or valleys, and the transition at 80HZ crossover between mains and sub was smooth. I also verified this with my ears when listening to frequency sweep tones on DVE.


Regards,


HDD


----------



## bpape

Dangeresque -

Treatments like that are upper mid/high frequency only - at best. They're also inherently something that's done to the whole wall surface - which may or may not be acoustically correct for a given room. While I'm sure it would work wonderfully for board rooms and other places where the vocal range is paramount, in a broadband room I'd avoid them.


HardDrive,


When you take your measurements, you need to do them at 1 -2Hz intervals. Anything coarser will hide problems that can be pretty steep. I'll guarantee you that you're having bass issues. While it may not be frequency response related, it's absolutely decay time related.


In that room, you're going to need some control spread throughout the room. For starters, as Glenn said, kill the front wal and make sure you have ALL of the early reflection points covered on the side walls. From there, you can do an analysis and determine where you stand in terms of a target for your room and usage.


I'd just plan on some soft broadband bass absorbtion in at least 2 of the corners. This will not only help with the bottom end control but will also, if constructed correctly, provide some of the overall decay time absorbtion you need.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> When you take your measurements, you need to do them at 1 -2Hz intervals. Anything coarser will hide problems that can be pretty steep.



HardDrive might be referring to burning Ethan's test tones to CD and those are, I believe, at 1 Hz intervals. It's certainly not the easiest way to check system/room response, but he's ahead of a lot of people who do nothing. This method can also serve as a "gateway" that whets one's appetite and leads to acoustical testing software and a better microphone. It has for me.


----------



## bpape

Agreed. Absolutely better than not doing anything. Just trying to make him aware that issues may be 'hiding' in the details that can easily be missed with 1/6 or even 1/12th octave tones. I don't know what he is using specifically.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Agreed. Absolutely better than not doing anything. Just trying to make him aware that issues may be 'hiding' in the details that can easily be missed with 1/6 or even 1/12th octave tones.



Very good point, and he's now aware of it, which hopefully will cause him to dig deeper into the subject of his test tones.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> HardDrive might be referring to burning Ethan's test tones to CD and those are, I believe, at 1 Hz intervals. It's certainly not the easiest way to check system/room response, but he's ahead of a lot of people who do nothing. This method can also serve as a "gateway" that whets one's appetite and leads to acoustical testing software and a better microphone. It has for me.



Actually doing the test that way SUCKS!!! Trust me you will want to go kill someone after spending 1 hour listening to test tones..









If you are going to test it is best to download ETF software.. Doing the test takes about 5 seconds and as I have learned you really should do 10 tests to to get things right.. so if you use the test tones give yourself 10 hours!! ha ha ha


BTW, this is in no way taking away from the fact that Ethan Winner took the time to put this on his website, which you can download for FREE!!!!


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Actually doing the test that way SUCKS!!! Trust me you will want to go kill someone after spending 1 hour listening to test tones..



True, but I was practicing tact.


----------



## Kevin12586

If we shouldn't use 1Hz increments, what would be better, 5Hz, 10Hz?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If we shouldn't use 1Hz increments, what would be better, 5Hz, 10Hz?



Oooh, 1 Hz is the right increment. Respectfully to Ethan, it's the test CD generated from his website that's, um . . . unwieldy.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> True, but I was practicing tact.



sorry if I came off untactful, I just remember doing the test that way myself.. It cost me a lot of years of therapy..










Glenn


----------



## HardDrive

Thanks for all of the advice. I'm sure the tones I used were more like 5-10HZ steps. So I'm missing alot, woundn't be the first time. My plan is now to treat front and side walls with DIY absorbers, then build a bass trap for each front-side corner. Unfortunately, there are many projects on my honey-do list, so it could be several months before I get to making the treatments and traps.


In the meantime, can anyone point me to some ETF software and the required equipment? In the past this seemed pretty expensive, so I went the burn your own test tones and use an SPL meter route. That was over a year ago, so maybe things have gotten more affordable since then.


Thanks for the help and advice!


HDD


----------



## pepar




> Quote:
> Originally Posted by *HardDrive* /forum/post/0
> 
> 
> In the meantime, can anyone point me to some ETF software and the required equipment? In the past this seemed pretty expensive, so I went the burn your own test tones and use an SPL meter route. That was over a year ago, so maybe things have gotten more affordable since then.



ETF and its successor, RPlusD can be found here . The software is $150 and the calibrated mic and preamp are another $325. On the brighter side







, Room EQ Wizard is free and can be found here . The ETF package is still _relatively_ inexpensive, but free is obviously better. I've got them both, but have not yet used REQ, nor am I qualified to compare the two tit-for-tat. Regardless, I recommend a better mic than the Rat Shack unit.


----------



## HardDrive




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> The software is $150 and the calibrated mic and preamp are another $325. Room EQ Wizard is free ... I recommend a better mic than the Rat Shack unit.



The mic and preamp are going to cost far more than the room treatments themselves, though it does seem that the RS meter can work as a mic. Still need a soundcard with line-level ins and outs. I'll take the advice of many and treat first, EQ second.


Thanks for the info.


HDD


----------



## ebr

Just FYI - a Behringer mic and pre-amp can be had for around $100 for the pair if you look around...


----------



## David French

I've been wondering if the Nady CM-100 might be an even more economical solution. Plus, you could sleep easier knowing that you haven't supported Behringer!


----------



## pepar




> Quote:
> Originally Posted by *HardDrive* /forum/post/0
> 
> 
> The mic and preamp are going to cost far more than the room treatments themselves, though it does seem that the RS meter can work as a mic. Still need a soundcard with line-level ins and outs. I'll take the advice of many and treat first, EQ second.



I'm not so sure about the first part. I did mine DIY and have "somewhat" more than $325 in them so far and am about to add a bit more for bass traps. The RS meter _can_ work as a mic, but not a particular accurate one. There are chartsx floating around - "inaccuracy charts" in my jargon - but that assumes a level of QC (unit-to-unit) that I just don't think is there.


----------



## pepar




> Quote:
> Originally Posted by *David French* /forum/post/0
> 
> 
> I've been wondering if the Nady CM-100 might be an even more economical solution. Plus, you could sleep easier knowing that you haven't supported Behringer!



Inside joke?


----------



## Kevin12586

Does anyone have any experience, good or bad, with the NCH Tone Generator ?


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Inside joke?



I think he is referring to Behringer not being the most up to par stuff on the market.. They have always been know for have the bottom line quality when it comes to studio equipment..



Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> I think he is referring to Behringer not being the most up to par stuff on the market.. They have always been know for have the bottom line quality when it comes to studio equipment..



Gotcha! But how is the BFD for notching out a few nodes in a home theater? It's my understanding that ADC/DAC conversions and signal degradation is not an issue at subwoofer frequencies. Bottom line: How does it SOUND compared to an SMS-1?


----------



## David French

Yes, Glenn nailed it. I sometimes forget that not everyone is coming from a recording engineering background like I am.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Gotcha! But how is the BFD for notching out a few nodes in a home theater? It's my understanding that ADC/DAC conversions and signal degradation is not an issue at subwoofer frequencies. Bottom line: How does it SOUND compared to an SMS-1?



I have no idea on that maybe Terry could chime in.. I would tend to think that the SMS-1 (which I have not used) is better quality.. Also I am not a big fan of EQ anyway..









Behringer's stuff works, but if you work in music day in and day out you will find it breaks down a lot and the sound quality is not as good as other products.. I am talking more the studio side of things so this may not apply to the listening rooms/HT market..


Glenn


----------



## bpape

For a sub only, it would be fine IMO. I'd never put it on my mains though.


If you don't want to spend the $$$ on ETF, you can check out JohnPM's freebie Java based tool. There's a thread for it in this forum titled Room EQ Wizard.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> For a sub only, it would be fine IMO. I'd never put it on my mains though.
> 
> 
> If you don't want to spend the $$$ on ETF, you can check out JohnPM's freebie Java based tool. There's a thread for it in this forum titled Room EQ Wizard.



Thanks. Actually, I purchased ETF a year or so ago and have d/l'd the free upgrade to RPlusD. Got John's app as well. Haven't looked at either yet, but will soon. Until I can build bass traps, I just need to generate a sweep up to 100Hz or so and set my PEQ to enjoy the system with some friends next month.


----------



## Kevin12586

Can anyone tell me if this is a good price for some rigid fiberglass.


The manufacture is Knauf and the panels are the equivalent of OC 703, 2" thick and 2x4 panels. For this I am being charged $55 for a bundle of 10-2x4 panels.


What do you think?


----------



## sdspga

I think I am embarrassed by what I paid for OC 703!! That sounds pretty good to me.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Can anyone tell me if this is a good price for some rigid fiberglass.
> 
> 
> The manufacture is Knauf and the panels are the equivalent of OC 703, 2" thick and 2x4 panels. For this I am being charged $55 for a bundle of 10-2x4 panels.
> 
> 
> What do you think?



I just ordered 2" Owens Corning 703 plain (unfaced) 24" x 48" for $.65/SF. That's $5.20 per panel with *12* per pack being $62.40. If all things are equal, the price you paid seems pretty good.


----------



## bpape

Agreed. Knauff makes several 2" products - just verify what you're getting. If it is the equivalent product, it's a very good price.


----------



## JamesE

I paid $.91 \\sq ft. 1 1/2 years ago. I'd say it was a very good price.


----------



## Kevin12586

Thank you everyone, I just wanted to make sure that it is a good price before I purchase


----------



## myfipie

Really guys if you plan to build them then I would go with Sensible Sound Solutions.. Yes you may pay a little more but you can rob Bryan of free advise..










Glenn


----------



## jmprader

I recently purchased DIY material from Bryan, so I hope I have a few credits for a bit of free advice that might help some others at the same time.


My room is about 16.25 x 22.75 and has a ceiling that starts at 8' along the long walls rising to 10' in the center of the room. Facing material came this week and we are ready to make the frames for the 703 material and acoustical cotton corner traps, but I'd like to take into consideration anything that you smart guys deem important due to the ceiling. We are going to do some corner traps for the bass and some panels to tame slap echo on the walls and ceiling.


I'm curious if there are any "general rules" that apply to non parallel ceilings when it comes to additional treatments, especially as it pertains to the lower registers. I have some problems with a couple of nulls in the bottom end (mid-30's and early 60's) and and mid-bass (don't recall the frequencies offhand). Any general hints that apply when we are dealing with something other than a traditional 6 surface cubical room (ceiling soffit at the peak, higher likelihood of needing soffit treatments at the wall/ceiling vertex).


Thanks guys.


----------



## bpape

Hey John.


There are a couple of things with a ceiling like that.


- There is no real corner so you can't run bass absorbtion there (unless you want to square it off and make it look like a rectangular soffit - done that before - works well)


- Angles surfaces like that can reflect things back at the seating position at odd angles. Just like the others though, you can plot the points with a buddy and a mirror and address them. Also potentially right beside each row of seating on the angle.


If you did the fake soffit thing, it will deal with both issues if you fill it with absorbtion - you get some bass control, good speading of absorbtion throughout the space, and killing any direct reflections off that angle.


Bryan


----------



## Equusz

What's the best way to cut a rigid fiberglass panel if you need to contour it?


----------



## bpape

What kind of contour? If you're just wanting to cut a bevel, you can use a table saw with a very fine blade. If you want a radius, you'll almost have to resin harden the edges and use a router on it though that's pretty tough.


----------



## pepar




> Quote:
> Originally Posted by *Equusz* /forum/post/0
> 
> 
> What's the best way to cut a rigid fiberglass panel if you need to contour it?



I've done contouring with a cheap electric razor. I emphasize "cheap" because you will not want to shave with it after cutting 'glass. Cutting it in a straight line, as Brian said, can be done with a fine blade on a table saw. If precisenss is not an issue, a _very sharp_ - *razor-sharp* six-inch knife works.


----------



## MisterG12

The method I used was a cheap electric knife I bought

at the grocery store (Procter Silex Easy Slice 9.99.) It will cut any contour you

throw at it. Best 10 bucks I ever spent. No mess to boot.

Matt


----------



## pepar




> Quote:
> Originally Posted by *MisterG12* /forum/post/0
> 
> 
> The method I used was a cheap electric knife I bought
> 
> at the grocery store (Procter Silex Easy Slice 9.99.) It will cut any contour you
> 
> throw at it. Best 10 bucks I ever spent. No mess to boot.
> 
> Matt



Cool, that sounds even better. I've got a bass trap project coming up soon and will give it a shot. Thanks!


----------



## Westshorestudios

I want to make absorbtion panels to tone down the mid to low high (basically foot traffic and speech and radio) frequencys in a bonus room which is being turned into an art studio for teaching. I'm not concerned about low / subwoofer type frequencies.


The room is about 900 feet, with wood (laminate) floors, windows, and sheet rock walls. There will not be carpets, rugs, etc. The room is very, very, very live. I have a few questions:


1. Is there a formula / rule of thumb for determining how many square feet of absorbtion panels I need to tame this room?


2. I plan to buy OC 703 (3 pound density rigid fiberglass) and wrap those panels in fabric (adhere fabric to fiberglass with spray adhesive), then velcro the panels to the walls and/or ceiling. For simplicity, I don't really want to build frames around the fiberglass.


Is this a recommended way to do this? Or do I need the frames for structural integrity? If the frames are needed, I can do that, but from a time and money standpoint, if they aren't necessary, I'd rather not.


(The panels need to look good, but not as good as GPowers theater! )


Thanks for you help.


----------



## Westshorestudios

I finally found a good search that answered some of my questions. I still need help with:


1. Is there a formula / rule of thumb for determining how many square feet of absorbtion panels I need to tame this room?



Thanks


----------



## Tweakophyte

Hi-


I found a great deal on Speaker Cloth to use for acoustic panels that you might like. I posted it here. 


Hope this helps,


----------



## BritInVA

I've been auditioning speakers ($2,000 to $2,500 for full 7.1) and thought I had made up my mind using Def Tech BP7006 Fronts. However, these are Bipolar speakers and I have read some earlier comments in this thread that even with Bipolar speakers the screen wall should still be treated with 1" of acoustic material.


This obviously is going to wipe out majority of that rear propagated sound.


I just can't get my head around why a reputable company like Def Tech (and others) design Bipolar front speakers if these rear reflections are so bad.


I'm no audiophile and room will be 99% movies.


I'm really not sure what to do.










My options seem to be:

1) Stick with the Bipolars and not treat screen wall (just 1st reflections that impact listening position and bass traps) and hope I still like the sound (and make sure good return policy).

2) Keep looking for Mono pole speakers (going to try to adition 3x CLR2003 to see if they sound similar)


Are there are others out there that have used Bipolar speakers in a HT proscenium build? (especially if your in the NoVA area).


[EDIT] I did ask some Q's in Speaker Forum but thought some advice from the acoustic folks would be useful [/EDIT]


----------



## pepar




> Quote:
> Originally Posted by *BritInVA* /forum/post/0
> 
> 
> I've been auditioning speakers ($2,000 to $2,500 for full 7.1) and thought I had made up my mind using Def Tech BP7006 Fronts. However, these are Bipolar speakers and I have read some earlier comments in this thread that even with Bipolar speakers the screen wall should still be treated with 1" of acoustic material.
> 
> 
> This obviously is going to wipe out majority of that rear propagated sound.
> 
> 
> I just can't get my head around why a reputable company like Def Tech (and others) design Bipolar front speakers if these rear reflections are so bad.
> 
> 
> I'm no audiophile and room will be 99% movies.
> 
> 
> I'm really not sure what to do.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> My options seem to be:
> 
> 1) Stick with the Bipolars and not treat screen wall (just 1st reflections that impact listening position and bass traps) and hope I still like the sound (and make sure good return policy).
> 
> 2) Keep looking for Mono pole speakers (going to try to adition 3x CLR2003 to see if they sound similar)
> 
> 
> Are there are others out there that have used Bipolar speakers in a HT proscenium build? (especially if your in the NoVA area).



I'm not the expert here, nor did I stay at a Holiday Inn Express last night







, but I *think* the front wall should be covered regardless of the speakers used. I happen to have a false wall to hide such things, but my front is completely lined with 2" J-M Linacoustic.


----------



## bpape

The issue with a bipole in a multi-channel environment is that you're between a rock and a hard place. The speaker is voiced and balanced to have that back information as part of the balance. But if you leave the wall live, then you're messing up your front soundstage with information from the surrounds coming back at you. In a 2 channel environment, this is not as much of an issue as the front wall can be left a bit less dead.


I think you have 3 options.


1. Use diffusion behind the speaker. This will at least still scatter the sound from the rear wave and from any reflections to minimize the effects. Downside is that effective diffusion is relatively 'thick' for front wall usage unless you have a false wall.


2. Do nothing behind the speaker. ONLY do this behind the rear driver(s) over maybe a 30 degree cone. This will still keep most of the wall relatively dead but allow the speaker to retain it's voicing and balance with a minimal compromise to reflection control.


3. Don't use a speaker with this type of design so it's a non-issue.


To me, in your situation where you don't yet have speakers and HT is 99% of the usage, #3 seems like a no-brainer. If not, then #2.


----------



## BritInVA

bpape - for now I'm going with #3 and will revert to #2 should I not find anything else to my liking (and in my budget).


Thanks,

Mark


----------



## bpape

Don't get me wrong - #2 will work if you have the room and money for the diffusion.


----------



## BritInVA

By diffusion you mean using Linacoustic or similar accross screen wall and 2ft up side? If yes this is my plan.


I'm going to continue to demo speakers ----- got at least a month before I need to start making final decision ---- so plenty of time.


I was really trying to home in on speaker choice so I can build for my in-ceiling rear surrounds. From those I've looked into so far (DefT, Polk, Sonance) providing I box and leave 0.75 to 1 cu ft of volume I should be OK.


----------



## pepar




> Quote:
> Originally Posted by *BritInVA* /forum/post/0
> 
> 
> By diffusion you mean using Linacoustic or similar accross screen wall and 2ft up side? If yes this is my plan.



Linacoustic, as far as I know, is only a fiberglass product. I've never heard of it as being anything else.


----------



## BritInVA




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Linacoustic, as far as I know, is only a fiberglass product. I've never heard of it as being anything else.



But this is what many have been using on their screen walls and along side walls up to 44" (or so).......are you saying this is wrong?


----------



## pepar




> Quote:
> Originally Posted by *BritInVA* /forum/post/0
> 
> 
> But this is what many have been using on their screen walls and along side walls up to 44" (or so).......are you saying this is wrong?



No, I have it there too, but it's fiberglass for absorption. Diffusion is always hard - reflective. Go here and click on the two styles of diffusion they sell.


----------



## BritInVA

OK - Thanks - Think I get it now










Diffusion is not in my current plan - just absorption on Screen wall and on panels along the side walls. Not decided yet about bass traps (still need to do some research)


----------



## pepar




> Quote:
> Originally Posted by *BritInVA* /forum/post/0
> 
> 
> Not decided yet about bass traps (still need to do some research)



Skip the research, unless you have a HUGE room, you _will_ benefit from bass traps. Notice I did not say you NEED them, only that you'll benefit. Of course, once you have them, you will NOT want to be wthout them. And then you'll think that you needed them.


----------



## mavromatis

Gentlemen,


I don't understand which type of acoustical backing I should use on my back and side walls. What is the rule of thumb? Over 40 pages of posts, and I still don't understand what you all are talking about.











I was thinking of using homosote? Would that do the trick?


Danny


----------



## bpape

Panels can be done several ways. Some people use Linacoustic up to ear level then batting above. Others use hard or empty panels in some places and 703/cotton panels in others depending on reflections and general distribution of absorbtion througout the room.


----------



## Dennis Erskine

Whether or not you want diffusion or absorption in the areas indicated will depend on several factors:

1. Are these panels in mirror points for the seating positions? If so, if your speakers have excellent off axis response, you want diffusion. With poor off axis response you'll want absorption.

2. Based upon the total of all materials in the room, what is the predicted decay time and, based on that, is more, or less, absorption needed (at what frequency ranges)

3. And, be real careful about bass traps. Most of them do nothing in the 80Hz and below range ... the first three or four (and most audible) axial modes in the typical room are below 80Hz. Most bass traps are also serious absorbers at all frequencies above 120Hz and can result in over absorption, reduction of room reverberation way below what you'd want, and you can find yourself needing to get more powerful amps and then speakers that can handle the addition power.


----------



## Kevin12586




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> 3. And, be real careful about bass traps. Most of them do nothing in the 80Hz and below range ... the first three or four (and most audible) axial modes in the typical room are below 80Hz. Most bass traps are also serious absorbers at all frequencies above 120Hz and can result in over absorption, reduction of room reverberation way below what you'd want, and you can find yourself needing to get more powerful amps and then speakers that can handle the addition power.



If I read this correct, it is possible to have too many bass traps in a room? I was always under the impression from reading this thread that as long as you have a bass trap in each corner, you won't do any 'damage' to the sound, only improve it. Am I mistaken?


----------



## myfipie




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If I read this correct, it is possible to have too many bass traps in a room? I was always under the impression from reading this thread that as long as you have a bass trap in each corner, you won't do any 'damage' to the sound, only improve it. Am I mistaken?



In the context of what he is talking about the answer is no. What Dennis is speaking about is using bass traps that are more broad band. Meaning the traps are actually picking up more high end then low end. This is sometimes good, but we have found that a bass trap that has a limp membrane system in it has the proper balance. More low end then high end. Leaving the room with tight bass but keeping life (high end) within the room. Dennis is right about most bass traps don't perform as well below (ok I am going to change that







) 50 to 60 hz.


Glenn


----------



## Terry Montlick




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If I read this correct, it is possible to have too many bass traps in a room? I was always under the impression from reading this thread that as long as you have a bass trap in each corner, you won't do any 'damage' to the sound, only improve it. Am I mistaken?



Yes, you *can* have too many bass traps, though it would take quite a few. With too much low frequency absorption compared to high, the room will sound too bright. There are optimal levels of reverberation for different room sizes and room purposes (2 channel, movie surround, etc.), and the ideal thing is to make these reverberation times close to the same over all frequencies.


Regards,

Terry


Edit: Glenn, we seem to disagree.


----------



## Kevin12586

So as long as I place my bass traps in each corner (about 14) and treat the first reflection points from each seat and speaker, as well as the front wall, then my room shouldn't be too dead or live? Is this 'fairly' accurate?


----------



## myfipie




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> So as long as I place my bass traps in each corner (about 14) and treat the first reflection points from each seat and speaker, as well as the front wall, then my room shouldn't be too dead or live? Is this 'fairly' accurate?



I believe you would be fine. Not sure if you really need 14 bass traps though.


Glenn


----------



## myfipie




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Yes, you *can* have too many bass traps, though it would take quite a few. With too much low frequency absorption compared to high, the room will sound too bright. There are optimal levels of reverberation for different room sizes and room purposes (2 channel, movie surround, etc.), and the ideal thing is to make these reverberation times close to the same over all frequencies.
> 
> 
> Regards,
> 
> Terry
> 
> 
> Edit: Glenn, we seem to disagree.



No I think we agree.







It is all about balance. But it takes a lot more bass traps then HF treatment and that is the reason why I like the membrane system in bass traps. It seems to give the right balance.







Now not every room is the same so this is a general statement and for small rooms.


Glenn


----------



## mavromatis

Thanks Dennis & bpape for the response.


Dennis, I do have a couple questions...


1) you state that if the panels are in mirror points (first order reflection point), I'll want diffusion. What material is recommended for diffusion? Then for the reset of the panels, what is recommended? Plywood? Homosote? Fiberglass?


2) How do I figure out the predicted decay time? The room is 20x15 but the actual area (non-stage) is about 16x15. The stage and room is carpeted, I do have wood panels on the angled part of the stage left and right (see rendering above).


3) Bass traps... I'm clueless... wasn't even considering them.


Thanks for the help... I'm doing fabric stretch walls, so if I don't get it all right the first time... the idea is, I can tweak them later...


Danny


----------



## Kevin12586




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> I believe you would be fine. Not sure if you really need 14 bass traps though.
> 
> 
> Glenn


 Here is the layout of my basement, my theater is in the top portion, from left to right, but it is also open to the rest of the basement. Because of this, and the soffits that run across the basement, if you count all corners and soffit corners, it comes to 14 bass traps. Because it is open, I figured it would be best to treat all corners, not just the ones in the theater.


----------



## myfipie




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> Here is the layout of my basement, my theater is in the top portion, from left to right, but it is also open to the rest of the basement. Because of this, and the soffits that run across the basement, if you count all corners and soffit corners, it comes to 14 bass traps. Because it is open, I figured it would be best to treat all corners, not just the ones in the theater.



Well 14 traps will work pretty well, but I would start with 8 traps and see how it sounds. Focus on the front corners and corners close to sitting. I can see why you want to do what you are saying though. I would start with 14 panels myself (maybe more) but I get them for FREE.










Glenn


----------



## Kevin12586

Where I am buying my panels from, they come in bundles of 10 and I will be buying 2 bundles. I might as well do the 14 at once since I will have so much left over if I only did 8 panels. Thanks for the advice though.


----------



## mavromatis

What do bass trap panels look like?


----------



## affeking




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Where I am buying my panels from, they come in bundles of 10 and I will be buying 2 bundles. I might as well do the 14 at once since I will have so much left over if I only did 8 panels. Thanks for the advice though.



Confused - couldn't you just buy 1 bundle if you were to try 8?


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> 3. And, be real careful about bass traps. Most of them do nothing in the 80Hz and below range ... the first three or four (and most audible) axial modes in the typical room are below 80Hz. Most bass traps are also serious absorbers at all frequencies above 120Hz and can result in over absorption, reduction of room reverberation way below what you'd want, and you can find yourself needing to get more powerful amps and then speakers that can handle the addition power.



Any suggestions on how to deal with problems at 80Hz and below? TIA!


Edit: OK, after reading subsequent posts, I'm thinking the answer to my question is "membrane" trap? Whazzat and where do I find one (or plans to build one) for my problem frequency?


Further, I just bought 2" unfaced 703 to make "SuperChunks" for three of the four corners in my room and three areas where the wall meets the ceiling, two 48" sections above my front L&R FRP absorbers and one 96" section above my rear FRP absorber. Does this seem, on the face of it, way too much or way too little? TIA, again!


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Any suggestions on how to deal with problems at 80Hz and below? TIA!
> 
> 
> Edit: OK, after reading subsequent posts, I'm thinking the answer to my question is "membrane" trap? Whazzat and where do I find one (or plans to build one) for my problem frequency?
> 
> 
> Further, I just bought 2" unfaced 703 to make "SuperChunks" for three of the four corners in my room and three areas where the wall meets the ceiling, two 48" sections above my front L&R FRP absorbers and one 96" section above my rear FRP absorber. Does this seem, on the face of it, way too much or way too little? TIA, again!



For DYI stuff you would want to use FRK on the fronts to have a membrane.


Glenn


----------



## myfipie




> Quote:
> Originally Posted by *mavromatis* /forum/post/0
> 
> 
> What do bass trap panels look like?



go to our website, you can see pictures of them or go to www.realtraps.com .


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> For DYI stuff you would want to use FRK on the fronts to have a membrane.
> 
> 
> Glenn



Thanks, I'm doing the SuperChunk trap with triangles of 703 stacked as opposed to a single 2x4 panel forming a hypotenuse across a corner. I guess I could make my own "membrane" and place it under the GOM covering the stack. I *think* I saw data that showed a solid stack of 703 as having better absorption at lower frequencies than a single panel - with or w/o a face - across a corner.


Should I "make" a membrane for the face of the SuperChunks? Can you point me to data that shows this would improve the performance at lower frequencies?


----------



## Kevin12586




> Quote:
> Originally Posted by *affeking* /forum/post/0
> 
> 
> Confused - couldn't you just buy 1 bundle if you were to try 8?



8 corners needs more than one bundle of 10-2x4 panels


I have another question, for my first reflection points from my front speakers, the panels will be mounted about 4' from the ground. I will be mounting my center channel speaker above my screen, 7' up in the air pointed down towards the sweet spot. Since it is pointed towards the sweet spot, do I still place a panel about 4' off the ground to treat the reflection from this speaker or should it be mounted higher?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> 8 corners needs more than one bundle of 10-2x4 panels
> 
> 
> I have another question, for my first reflection points from my front speakers, the panels will be mounted about 4' from the ground. I will be mounting my center channel speaker above my screen, 7' up in the air pointed down towards the sweet spot. Since it is pointed towards the sweet spot, do I still place a panel about 4' off the ground to treat the reflection from this speaker or should it be mounted higher?



Use a mirror or visualize your "bank shots" from the center speaker to the ears of the audience . . .


Don't forget to look at your ceiling.


----------



## Stima




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Thanks, I'm doing the SuperChunk trap with triangles of 703 stacked as opposed to a single 2x4 panel forming a hypotenuse across a corner. I guess I could make my own "membrane" and place it under the GOM covering the stack. I *think* I saw data that showed a solid stack of 703 as having better absorption at lower frequencies than a single panel - with or w/o a face - across a corner.
> 
> 
> Should I "make" a membrane for the face of the SuperChunks? Can you point me to data that shows this would improve the performance at lower frequencies?




A solid stack does SLIGHTLY better than a thick layer. Also, I plan to do the same "chunk" style as you, however I plan to put one FSK piece on the "front" of the stack to A) give it a smooth appearance, and B) provide a membrane for mid-hi freq. reflection. (As some have pointed out...bass traps made of 703 are essentially broad band absorbers. I already have enough absorption...thus the membrane for the "front".)


----------



## Kevin12586




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Use a mirror or visualize your "bank shots" from the center speaker to the ears of the audience . . .
> 
> 
> Don't forget to look at your ceiling.



Thinking of it as a bank shot makes 'perfect' sense and easier to figure out.


Thanks


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> A solid stack does SLIGHTLY better than a thick layer. Also, I plan to do the same "chunk" style as you, however I plan to put one FSK piece on the "front" of the stack to A) give it a smooth appearance, and B) provide a membrane for mid-hi freq. reflection. (As some have pointed out...bass traps made of 703 are essentially broad band absorbers. I already have enough absorption...thus the membrane for the "front".)



I'm now contemplating running some tests with and w/o a DIY "membrane" applied to the edges of the 703 pieces that make up the SuperChunk. As it is DIY, I get to select the material; _*can anybody give me some guidance on what weight paper to use? Or, should I use someting else entirely?*_


Is there something I can use to extend lower the effectiveness without losing the absorption up to ~300Hz?


A HUGE TIA on this one!!


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> A solid stack does SLIGHTLY better than a thick layer. Also, I plan to do the same "chunk" style as you, however I plan to put one FSK piece on the "front" of the stack to A) give it a smooth appearance, and B) provide a membrane for mid-hi freq. reflection. (As some have pointed out...bass traps made of 703 are essentially broad band absorbers. I already have enough absorption...thus the membrane for the "front".)



Two of the corners in my theater and one wall/ceiling juncture that are getting superchunks are behind my false wall, an area that is already lined with 2" J-M Linacoustic, so I don't believe they will be contributing any "additional" mid-/hi-frequency absorption to my room. And the remaining superchunks have such a small surface area compared to the rest of the untreated room I'm hoping they won't complicate things for me at the non-bass frequencies.


----------



## myfipie

How wide our the fronts of the super chunks?


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> How wide our the fronts of the super chunks?
> 
> 
> Glenn



I'm doing the 24" version.


----------



## mooney

What is FRK...and where do you get it?


Would it be used where my front corners are bridged with 24" wide 4" thick BAC floor to ceiling (9') ?


----------



## pepar




> Quote:
> Originally Posted by *mooney* /forum/post/0
> 
> 
> What is FRK...and where do you get it?
> 
> 
> Would it be used where my front corners are bridged with 24" wide 4" thick BAC floor to ceiling (9') ?



FRK is a Kraft paper facing that comes on fiberglass panels. I don't think it can be added later; the panels must be ordered that way.


Seen this ? The linked site has a wealth of information on all acoustical treatments.


----------



## bpape

Actually, FSK scrim is available separately. It can be attached using Scotch 77 spray adhesive very easily. This is generally a more cost effective solution than buying it already faced. While it won't act exactly the same as the factory bonded material, in practice, it's very, very close - probably closer than the variances in coefficients.


----------



## jandawil

I am about to figure out where to place my mineral wool sheets (24"X48"X4"). I was originally going to make corner traps with triangles in the back corners, but I think it will be difficult to make them look good. I have room behind my screen wall and than I don't need to worry about a finished look. Is there any benefit to putting them on the back wall corners as opposed to front?? Also any advantage over corners vs. where ceiling meats walls. Thanks everyone.


----------



## Stima

From what I understand...a corner is a corner, regardless of location. Every corner will produce some kind of "hump" in the bass frequency response.


Given that understanding...I would say go ahead with bass traps behind your screen. I will be putting traps behind my screen and have said so here on a couple occasions. I haven't heard any warnings or cautions yet.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Actually, FSK scrim is available separately. It can be attached using Scotch 77 spray adhesive very easily. This is generally a more cost effective solution than buying it already faced. While it won't act exactly the same as the factory bonded material, in practice, it's very, very close - probably closer than the variances in coefficients.



OK, I really need to stop answering questions that I specifically do not know the answer to.










If one is attaching something after the fact (of buying them plain), is there something BETTER to use than FSK?


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/0
> 
> 
> I am about to figure out where to place my mineral wool sheets (24"X48"X4"). I was originally going to make corner traps with triangles in the back corners, but I think it will be difficult to make them look good. I have room behind my screen wall and than I don't need to worry about a finished look. Is there any benefit to putting them on the back wall corners as opposed to front?? Also any advantage over corners vs. where ceiling meats walls. Thanks everyone.



I'd start there - I will be as I have the same situation - and maybe that'll do it. If not, additional traps may be needed. I will also be "chunking" the ceiling/wall intersection behind my false wall as well.


----------



## jandawil




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> From what I understand...a corner is a corner, regardless of location. Every corner will produce some kind of "hump" in the bass frequency response.
> 
> 
> Given that understanding...I would say go ahead with bass traps behind your screen. I will be putting traps behind my screen and have said so here on a couple occasions. I haven't heard any warnings or cautions yet.



Nice thanks guys for the info. It will make my job MUCH easier and actually allow me some wider traps.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> From what I understand...a corner is a corner, regardless of location. Every corner will produce some kind of "hump" in the bass frequency response.



Corners produce tangent or oblique room mode "humps," which are generally lower in size than axial room modes. Axial room modes are produced by opposing wall surfaces only. To the degree that a corner trap will cover a wall, it may reduce an axial room mode. However, the relationship between how much you have to span a wall or corner and how much the room modes are reduced is neither simple nor well understood.


Keep those traps a-trappin'!


Regards,

Terry


----------



## Stima

After watching the videos over on Realtrap...I got to thinking the amount of bass traps I am planning on will not be enough.


I roughly have a 18'x11'x8' room (not counting the area behind my AT screen). The Q will be pretty low as I only used a single layer of drywall. I had planned on 6, 24"x48"x4" 703 FSK panels (1"x4 sheets).


I had planned on the following layout: one each across the rear\\side wall corners, one behind the rear seats (floor to rear wall corner), and three behind my AT screen. Since the wall behind my screen is actually the area under a bay window, the wall is made of three 50" sections. I plan to put one trap across the floor to center portion corner, and one each across the two 145 degree angles.


On to my questions: in the video, they state 8 traps is generally the right amount to use in a typical home theater room. So, A) is my room typical, B) should I sacrifice aesthetics to put traps along the left and right sides of the theater in order to get 8 traps instead of 6, C) can I make my 6 traps 2" thicker to achieve the same bass control, and D) finally, EVERY sheet of 703 I have is FSK...I can't remember if I am supposed to tear off all the FSK except one, or leave it on every sheet.


THANKS IN ADVANCE for any help!!


----------



## TumaraBaap

Stima,


making 6 traps thicker will help a little but probably won't make up for the surface area of 8 traps. Bass absoption is challenging, and short changing the number of traps won't help.


703 is an adequate material for 1st reflaction points, but denser stuff is preferred for bass traps. 705 FSK perhaps. FSK should only be on one side of the trap; the side facing into the room.


Ethan goes over all of this at http://www.ethanwiner.com/acoustics.html


----------



## Stima

Oops, I meant 705!! I have been putting up 703 all day and had that on the mind!










SURFACE AREA!! Yeah...that would be more important than thickness. I will re-read Ethan's write up. I will also look into it about FSK. I don't remember him stating anything about removing ALL the layers or just leaving them be with the last layer facing the room.



***EDIT***


After re-reading...I confirmed your advice to remove all but one layer.










Surface area was also discussed, but I didn't quite understand how to correctly compute absorption coefficients since the manufacture doesn't take into consideration all surfaces.


----------



## myfipie




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> After watching the videos over on Realtrap...I got to thinking the amount of bass traps I am planning on will not be enough.
> 
> 
> I roughly have a 18'x11'x8' room (not counting the area behind my AT screen). The Q will be pretty low as I only used a single layer of drywall. I had planned on 6, 24"x48"x4" 703 FSK panels (1"x4 sheets).
> 
> 
> I had planned on the following layout: one each across the rear\\side wall corners, one behind the rear seats (floor to rear wall corner), and three behind my AT screen. Since the wall behind my screen is actually the area under a bay window, the wall is made of three 50" sections. I plan to put one trap across the floor to center portion corner, and one each across the two 145 degree angles.
> 
> 
> On to my questions: in the video, they state 8 traps is generally the right amount to use in a typical home theater room. So, A) is my room typical, B) should I sacrifice aesthetics to put traps along the left and right sides of the theater in order to get 8 traps instead of 6, C) can I make my 6 traps 2" thicker to achieve the same bass control, and D) finally, EVERY sheet of 703 I have is FSK...I can't remember if I am supposed to tear off all the FSK except one, or leave it on every sheet.
> 
> 
> THANKS IN ADVANCE for any help!!



A) No room is typical, but I have found that 8 traps do work pretty well.. See case study at http://www.sbrjournal.net/currentiss.../Acoustics.htm 

I would focus on the front 2 corners of your room and put the panels floor to ceiling if you can

B) You can put panels on side walls but straddle floor to wall or ceiling to wall, if you are going for bass trapping

C) We have a 6" trap that does VERY well but it does not replace the amount of traps. For the most part.

DA) I would leave the FSK on the panels that are straddling walls. For first reflections you want to remove it.


Glenn


----------



## DMF

Remember that there are more corners in a room than the vertical corners. Where the wall joins the ceiling is also a corner - one that I rarely see used for bass traps.


----------



## Stima




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> A) No room is typical, but I have found that 8 traps do work pretty well.. See case study at http://www.sbrjournal.net/currentiss.../Acoustics.htm
> 
> I would focus on the front 2 corners of your room and put the panels floor to ceiling if you can
> 
> B) You can put panels on side walls but straddle floor to wall or ceiling to wall, if you are going for bass trapping
> 
> C) We have a 6" trap that does VERY well but it does not replace the amount of traps. For the most part.
> 
> DA) I would leave the FSK on the panels that are straddling walls. For first reflections you want to remove it.
> 
> 
> Glenn



Thanks for the link; I read through it and came away with the feeling I really need to get my hands on equipment similar to yours. The improvement in your bass response is quite dramatic!!


Concerning your advice to focus on the front corners; Since those corners are 145degree instead of a typical 90 degree....will straddling them still work as a bass trap? It will be very easy to straddle them from floor to ceiling, so if the angle doesn't screw up the functionality, I will be golden.


As far as the FSK, I plan to leave it on the three panels located in the rear of the room. Those were across the wall corners and floor to wall corner. What I had question on was whether to leave the FSK on all 4 sheets or just the sheet facing the room. According to Ethans write up, I would actually HURT the bass absorption if I were to leave it on EVERY sheet.


So, my new plan given straddling a 145 degree corner is viable:


Front wall behind screen: Two, 4 in. thick, floor to ceiling (@7.5 ft.) panels one each across the 145 degree corners. One, 4 in. thick, 4 ft. long panel across the floor to front wall corner. One layer of FSK left on, but facing wall rather open theater.


Rear wall behind seats: Two 4 in. thick, 4 ft. tall panels one each across the rear 90 degree corners. One 4 in. thick, 5 ft. long panel across the floor to rear-wall corner. One layer of FSK left on, however FACING theater.


This gives me essentially 8 panels worth of surface area coverage. This layout puts essentially 5 panels in front and 3 in the rear. I am hoping that is OK.


AGAIN everyone thanks for the thoughts and helping me talk through my ideas. If this forum wasn't here I don't know WHAT I would do for help! (Well besides pay big bucks for a pro to do it all.







)


----------



## myfipie

>As far as the FSK, I plan to leave it on the three panels located in the rear of the room. Those were across the wall corners and floor to wall corner. What I had question on was whether to leave the FSK on all 4 sheets or just the sheet facing the room. According to Ethans write up, I would actually HURT the bass absorption if I were to leave it on EVERY sheet.


----------



## TomBonge




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I just ordered 2" Owens Corning 703 plain (unfaced) 24" x 48" for $.65/SF. That's $5.20 per panel with *12* per pack being $62.40. If all things are equal, the price you paid seems pretty good.




Where did you find it for this Price?


----------



## pepar




> Quote:
> Originally Posted by *TomBonge* /forum/post/0
> 
> 
> Where did you find it for this Price?


 Here , but fuggedibout getting it there unless you're local and can pick it up. It is not practical to ship it UPS, Fed Ex or USPS. You need to find a large insulation contractor or an insulation distributor that is local to you. You now know what's possible pricewise; use that information to get the best deal you can.


----------



## David French

Here's another one that I never see mentioned:

LW Supply


----------



## TomBonge




> Quote:
> Originally Posted by *David French* /forum/post/0
> 
> 
> Here's another one that I never see mentioned:
> 
> 
> LW Supply




I went to the LW website and found that the have a location here in miami, but when I called they said they don't carry it. I have called a few other places and have had no luck yet.


----------



## pepar




> Quote:
> Originally Posted by *TomBonge* /forum/post/0
> 
> 
> I went to the LW website and found that the have a location here in miami, but when I called they said they don't carry it. I have called a few other places and have had no luck yet.



You should be able to go to your yellow pages or even YellowPages.com and search for "insulation." Or to to the manufacturer's website and look for distribution information. I located a Johns-Manville distributor in Philly and an Owens Corning one in Balto. that way with YellowPages.com or SuperPages.com. Recently, AVS'er craig john turned me on to a more local OC source - with even better pricing. This stuff is used by the TRUCKLOAD in the HVAC industry everywhere commercial construction is occurring.

Here's a raw list of twenty-five greater-Miami companies listed under "Insulation Materials Dealers." Call some more.


----------



## Bookhouseboy

I've just finished treating the first reflections in my HT with acoustic panels, and it's now time to address the bass frequencies.


Here's my plan:

I'm going to make bass traps out of 6" (2 x 3") thick rockwool acoustic panels. They are 2 feet wide and 4 feet long. I'm going to make frames and feet so I can move them around, not unlike the Mondotraps from Realtraps.com They're going to be placed in the five corners of the room, floor to ceiling.


My questions are:

1. How effective will these traps be, down to 80hz or is that too ambitious?


2. Should I make them even thicker, or is 6" enough?


I've gotten a lot of good tips from this thread, and Ethan Winers articles were really informative, but it's better to be a 100% sure what to do before I start. I hope you understand that.


----------



## pepar




> Quote:
> Originally Posted by *Bookhouseboy* /forum/post/0
> 
> 
> I've just finished treating the first reflections in my HT with acoustic panels, and it's now time to address the bass frequencies.
> 
> 
> Here's my plan:
> 
> I'm going to make bass traps out of 6" (2 x 3") thick rockwool acoustic panels. They are 2 feet wide and 4 feet long. I'm going to make frames and feet so I can move them around, not unlike the Mondotraps from Realtraps.com They're going to be placed in the five corners of the room, floor to ceiling.
> 
> 
> My questions are:
> 
> 1. How effective will these traps be, down to 80hz or is that too ambitious?
> 
> 
> 2. Should I make them even thicker, or is 6" enough?
> 
> 
> I've gotten a lot of good tips from this thread, and Ethan Winers articles were really informative, but it's better to be a 100% sure what to do before I start. I hope you understand that.



At this point I think you should "discover" StudioTips . This is a site devoted entirely to acoustics and acoustical treatments and is chock full of helpful information, including graphs comparing absorption of various traps. You might even get some trap design ideas. I'm doing SuperChunks myself.


----------



## Bookhouseboy

Thanks for the link, pepar.


The SuperChunk traps seem great, but it will take a lot of work to fill five corners, and it will also cost more because I would need more panels, if I were to use acoustic panels. I also like the idea of having mobile traps that I can move around or remove easily if I want to.


Is the SuperChunk more effective than the type of trap that I'm planning on using?


----------



## David French

As one of the resident StudioTippers here at AVS, with great pleasure, I give you this:

http://forum.studiotips.com/viewtopic.php?t=536


----------



## Bookhouseboy

Thanks, David, that's good information.


English is not my first language, and I don't understand what "sabins" mean, but is the conclusion that all three do a good job absorbing LF and that the Lenrd's has a bit of an advantage on the other two constructions? I could be very wrong.


----------



## pepar




> Quote:
> Originally Posted by *Bookhouseboy* /forum/post/0
> 
> 
> Thanks, David, that's good information.
> 
> 
> English is not my first language, and I don't understand what "sabins" mean, but is the conclusion that all three do a good job absorbing LF and that the Lenrd's has a bit of an advantage on the other two constructions? I could be very wrong.



Sabins are a unit of measure, but knowing any more than that is not necessary to interpret the graphs. To me, it looks like MegaLENRDs and SuperChunks perform closely, with StudioTips Corner Absorber - the design most like what you contemplate making - absorbing less at all frequencies. So yes, SSC is more effective than what you're planning. Apparently, the additional material "in the corner" is exactly what makes them more effective. So yes it will cost more. But even then, it's still pretty darn cheap - if you're "buying right." I just ordered 2" Owens Corning 703 plain (unfaced) 24" x 48" for $.65/SF. That's $5.20 per panel with 12 per pack being $62.40.


----------



## bpape

When you view those graphs on the studiotips site, just remember that those are normalized and for linear foot of corner - not for square foot of absorbtion. That said, the SuperChunk has almost 100% more square footage than the LENRD.


Now, if it were done per square foot of surface area, you'd see that the SuperChunk will outperform the LENRD. I'd bet at least 1 beer that below 60Hz (in the real world) that the chunk would pull away even further from the other 2.


----------



## Bookhouseboy

Thanks for clearing that up, pepar.


Both the MegaLenrd and the Superchunk seem to outperform the type of bass trap I'm planning on building. That's unfortunate, and I might have to reconsider my plans. Since I don't live in USA, I wont be able to buy these OC 703 that seem very popular to use as bass trap materiale. What other materiale is recommended - glass, fiber rockwool?


I'm glad that there are people with experience and knowledge about acoustic treatment on the Internet. I would otherwise be lost.


----------



## pepar




> Quote:
> Originally Posted by *Bookhouseboy* /forum/post/0
> 
> 
> Thanks for clearing that up, pepar.
> 
> 
> Both the MegaLenrd and the Superchunk seem to outperform the type of bass trap I'm planning on building. That's unfortunate, and I might have to reconsider my plans. Since I don't live in USA, I wont be able to buy these OC 703 that seem very popular to use as bass trap materiale. What other materiale is recommended - glass, fiber rockwool?
> 
> 
> I'm glad that there are people with experience and knowledge about acoustic treatment on the Internet. I would otherwise be lost.



Something to put this into context is that if you now have NO bass traps, adding almost anything will help. Owens Corning fiberglass products are sold internationally. Where do you live?


----------



## Bookhouseboy

pepar:

You have a good point, and putting some bass traps in the corners is a good idea wether I use the most effective construction or not. My problem is that I'm a bit afraid that making the wrong decisions would actually make the room even more unsuited for movie soundtracks. I'm not expecting my HT to sound like a million dollar theater, but I know there are things I can do for a moderate price. The first step was treating the ceiling, sidewalls and rear wall with acoustic panels, and I'm very pleased with the result. I probably should've started with bass traps since LF is the biggest problem in small rooms, but it's definitely next on my to do list.


I live in Norway, and I would have to pay a lot in taxes, and of course shipping and handling.


----------



## pepar




> Quote:
> Originally Posted by *Bookhouseboy* /forum/post/0
> 
> 
> pepar:
> 
> You have a good point, and putting some bass traps in the corners is a good idea wether I use the most effective construction or not. My problem is that I'm a bit afraid that making the wrong decisions would actually make the room even more unsuited for movie soundtracks. I'm not expecting my HT to sound like a million dollar theater, but I know there are things I can do for a moderate price. The first step was treating the ceiling, sidewalls and rear wall with acoustic panels, and I'm very pleased with the result. I probably should've started with bass traps since LF is the biggest problem in small rooms, but it's definitely next on my to do list.
> 
> 
> I live in Norway, and I would have to pay a lot in taxes, and of course shipping and handling.



The materials we've been discussing are specifically made for thermal and acoustical insulation and isolation, much of it in the HVAC trade (Heating, Ventilation and Air Conditioning). If they are building commercial buildings in Norway with heating and/or cooling systems, then there are contractors installing this stuff. If there are contractors installing it, then odds are there are distributors selling it to them. I must admit complete ignorance of the Norwegian construction industry and perhaps my assumptions are bogus. Have you searched the equivalent of our "yellow pages" telephone directory?


----------



## bpape

In Europe in general, I think you'd probably want to look toward mineral wool (rockwool). That seems to be more readily available there.


----------



## Kevin12586

Bookhouseboy, did you notice a difference in your sound after treating your first reflection points?


----------



## Stima

While skimming through http://www.bobgolds.com/AbsorptionCoefficients.htm , I noticed 705 has LOWER absoportion numbers than 703, yet everyone suggests 705 over 703 for bass traps.


Can anyone shed a little light on this?



Also, I was wondering what would be the effects of alternating 703 and 705 sheets in a Chunk style trap. Anyone care to guess?


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> While skimming through http://www.bobgolds.com/AbsorptionCoefficients.htm , I noticed 705 has LOWER absoportion numbers than 703, yet everyone suggests 705 over 703 for bass traps.
> 
> 
> Can anyone shed a little light on this?



I saw the same data and simply went with the 703. The traps on StudioTips seem to be made with it as well, as are many other commercially available traps I looked at before deciding to stick with DIY..


----------



## myfipie

There seems to be a lot of talk about which is better on low end, but I think everyone would agree that either way you go it is going to help.


Glenn


----------



## Bookhouseboy

Yes, Kevin12586, I did notice an improvement. The first thing that struck me was a better separation of instruments and sound effects. It's like the soundstage is clearer. The second thing I noticed was a better upper mid bass. The panels that I use don't absorb very low, but I guess cleaning up in the high frequencies does have an effect on mid bass. I also feel that the sound is much more pleasent and less "hard" than before. I can play at higher volumes without the treble being too aggressive.


pepar:

The rockwool panels I'm refering to are used in the industry, and are specially made for acoustical treatment, so I'm sure they'll do a good job as bass traps, as well as being safe.


I've decided to go on with my plans. Is 6" thickness enough, or should I use 8"?


----------



## Kevin12586

Thanks Bookhouseboy, I will be putting up panels in the next few weeks and I enjoy reading about other people's improvement; it makes me look forward to my improvement once I put up my treatment.


----------



## pepar




> Quote:
> Originally Posted by *Bookhouseboy* /forum/post/0
> 
> 
> Yes, Kevin12586, I did notice an improvement. The first thing that struck me was a better separation of instruments and sound effects. It's like the soundstage is clearer. The second thing I noticed was a better upper mid bass. The panels that I use don't absorb very low, but I guess cleaning up in the high frequencies does have an effect on mid bass. I also feel that the sound is much more pleasent and less "hard" than before. I can play at higher volumes without the treble being too aggressive.



Covering my FRP's with 2" OC SelectSound Black (see my link), including ceiling, L&R front walls *and* rear wall, made the same improvements; cleaned everything up, better front imaging, widened soundstage and better surround field/mains integration. And the fattening of the upper bass frequencies. Of course, I've since learned - by running some tests - that my fat upper bass is W-A-Y too fat, which is one of the main reasons I'm now working on bass traps.


----------



## Kevin12586




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Covering my FRP's with 2" OC SelectSound Black (see my link), including ceiling, L&R front walls *and* rear wall, made the same improvements; cleaned everything up, better front imaging, widened soundstage and better surround field/mains integration. And the fattening of the upper bass frequencies. Of course, I've since learned - by running some tests - that my fat upper bass is W-A-Y too fat, which is one of the main reasons I'm now working on bass traps.



Wow pepar, I didn't realize you didn't have bass traps yet. When you get them up, can you let us know and tell us of your overall impression?


----------



## Ethan Winer

Stima,


> While skimming through http://www.bobgolds.com/AbsorptionCoefficients.htm , I noticed 705 has LOWER absoportion numbers than 703, yet everyone suggests 705 over 703 for bass traps. Can anyone shed a little light on this?


----------



## Stima

Ethan,


Do you know of any data utilizing the "chunk" method?


As with your tests, any test with the chunk method would raise questions such as alternating material densities and FSK placement\\existance.


----------



## Bookhouseboy

kevin12586:

I'm sure you'll be happy with treating the first reflection points. Good luck!


pepar:

Good to hear that I'm not imagining the improvements. Before I install the bass traps, I'm gonna do a measurement in the lower frequencies to see how the graph changes after the traps are in place. I'm inspired by this link: http://www.sbrjournal.net/currentiss.../Acoustics.htm 



Ethan Winer:

If you have the time, could you give me some advice?

Your articles on room acoustics are great, but since my English is only ok, and my math skills likewise, I would be grateful for a little help.


The room is rectangular (20 x 13,5 feet) except for a 6,5 feet wide and 2 feet deep "outgrowth" in the left, front corner of the room. I'm planning to use five, one for each corner, bass traps similiar to the panels in your test. I'm gonna make them out of Rockwool acoustic panels, and I was planning to use 6" or 8" thickness and stack them from floor to ceiling like you did in your test, but after reading your conlcusion, I wonder if I maybe should go for a higher number of traps. What do you recommend? I'm new to acoustics, so please use as simple language as possible.


----------



## myfipie

I am sure Ethan will chime in but the more area you can cover the better it will work, instead of thickness. Now I believe this is comparing 8 4' panels will work better then 4 8' panels- this is only to a point-Bass trapping needs 4 or more inchs so spreading around 1" panels in your room is not going to do the job for the low end.



Glenn


----------



## myfipie

>Good to hear that I'm not imagining the improvements. Before I install the bass traps, I'm gonna do a measurement in the lower frequencies to see how the graph changes after the traps are in place. I'm inspired by this link: http://www.sbrjournal.net/currentis...s/Acoustics.htm


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Wow pepar, I didn't realize you didn't have bass traps yet. When you get them up, can you let us know and tell us of your overall impression?



Sure will, and will chronical it on my HT website. I will try to take some measurements before and after. As long as DIY projects like this take me, another day or two for taking proper measurements shouldn't make any difference.


----------



## Bookhouseboy

Thanks for taking the time to answer my question, myfipie.


I've used 1" panels (which works fine for frequencies above 500hz, if the lab numbers don't lie) for the first reflection points, but I'll use at least 2 x 3" panels for the bass traps. The panels are 2 feet wide and 4,7 feet long. Putting as many as eight or more traps that big in my HT is going to be a problem, but I guess compromising is not an option if you want to get the best out of your surround system.


I got the link from one of your earlier posts, and it was really interesting and inspiring to see the results Ryan got with his bass traps. It would be awesome to see my graph go from bumpy to near flat. He did use the BFD to flatten the last peaks, but I would be overly happy with anything even close to his graph.


----------



## BasementBob

Stima:



> Quote:
> I noticed 705 has LOWER absoportion numbers than 703, yet everyone suggests 705 over 703 for bass traps



I don't.

Do not use 705 for superchunks.

Optimal for a superchunk might be 701 as a face, and then 34" diagonal 703 behind it -- but it might depend on the room what's 'optimal'.


Depth is more effective at lower frequencies than more density -- and too much density simply means the sound won't go far enough into the material to be absorbed. Around a meter deep I'd consider using fluffy fiberglass pink instead of anything rigid.


You might want to play around with Chris Whealy's Porous Absorber Calculator.
http://www.bobgolds.com/whealy.com/a...cs/Porous.html 

IR-761 lists several materials and their Rayls

R11 3.5" 89mm fluffy fiberglass pink batt is 4800 mks rayls/m

Rockwool RWA45 (flow resistivity = 16,500 Rayls/m),

rockwool at 83mm, 98kg/m^3, 58800 mks rayls/m


----------



## Stima




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Stima:
> 
> 
> Do not use 705 for superchunks.
> 
> Optimal for a superchunk might be 701 as a face, and then 34" diagonal 703 behind it ...Depth is more effective at lower frequencies than more density...





> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> You might want to play around with Chris Whealy's Porous Absorber Calculator.




Currently, I *had* planned to do the 24" chunks with alternating 703 and 705 with a face of 703 (FSK facing out) to maximize materials on hand. If I needed more surface area, I could remove some 705 and put spaces in the columns hidden by the GOM. (I had planned to leave the FSK on the sheets because the membrane is at an extreme angle to the sound source. (180 +/- 30deg.)


So to prove to myself this setup is not best (as you suggest), I downloaded and ran the calculator. I did a search via Google to try and find a rayls/m for 703 and 705, and found an old NASA document quoting 14000 for 701, 27000 for 703 and nothing for 705. I would guess the number would almost double to 54000 for 705 given it doubled from 701 to 703. Also the numbers don't give any reference to FSK material...which we know affects absorption. Since it's missing on all materials, I could also guess the effect would be similar across the board. That being the case, if someone knows the rayls/m value of FSK, I would appreciate it to get a better feel for the true absorption of each product.


While playing around, I still found at 4", the 705 had better lower end absorption compared to the 703. Not by much after 60hz, but it did extend quite a bit lower.


Now, to put your 703 over 705 to the test, I went to 8" and 12". (Using the 24" pieces for superchunk would give a maximum depth of 12") Since there was no way to get a true reading for the superchunks method in the calculator, I could only look at differences between 4", 8" and 12". The difference was VERY apparent as the material got thicker. At 12" the 703 became the better trap than the 705 and MUCH MUCH better than either at 4".


All this to say, according to your calculator, given a choice between 703 and 705, when going above 4", the better choice is in fact the 703. (As you stated in your reply.








)


However, since there really is very little empirical data for various methods of chunk formation, I will probably have to resort to multiple in-home tests to figure which is best.


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> However, since there really is very little empirical data for various methods of chunk formation, I will probably have to resort to multiple in-home tests to figure which is best.



We look forward to your test results.


----------



## Ethan Winer

Books,


> after reading your conlcusion, I wonder if I maybe should go for a higher number of traps.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Books,
> 
> 
> > after reading your conlcusion, I wonder if I maybe should go for a higher number of traps.


----------



## BasementBob

pepar



> Quote:
> At what point do all those traps begin to negatively impact mids and highs?



If you have too many of them, then

a) you have to turn your speakers up to the point of distortion

b) you can overabsorb at higher frequencies, resulting in a less than pleasing room (aka anechoic)

c) the more absobers you put into a room there's a diminishing returns for absorbtion

d) more absorbers in the room may reduce the bass absorbtion average per square foot of absorber (i.e. you get a lot more HF absorbtion, but much less than the advertised bass absorbtion -- this isn't 'lying' manufacturers, it's just that the room is significantly different than the measured room).


----------



## Ethan Winer

Pepar,


> At what point do all those traps begin to negatively impact mids and highs?


----------



## BasementBob

Stima:



> Quote:
> Currently, I had planned to do the 24" chunks with alternating 703 and 705 with a face of 703 (FSK facing out)



It's not a studiotips superchunk if you've got FSK anywhere. It's an experiment.



> Quote:
> I did a search via Google to try and find a rayls/m for 703 and 705, and found an old NASA document quoting 14000 for 701, 27000 for 703 and nothing for 705.



I think I know the one you mean.



> Quote:
> Also the numbers don't give any reference to FSK material



Rayls is flow resistivity.

FSK is air tight so its flow resistivity is "infinity rayls/m"

The calculator is for porous absorbers, and FSK is not what I'd call porous.



> Quote:
> While playing around, I still found at 4", the 705 had better lower end absorption compared to the 703. Not by much after 60hz, but it did extend quite a bit lower.



Yep. Try it again at 24" thick. (EDIT: you did! see below)

Did you try multiple angles of incidence?

0.003% (i.e. 0.00003 multiplyer) of the sound goes straight into an absorber. Most of it is diffuse sound.

Here's an example of the effect in the first post of http://forum.studiotips.com/viewtopic.php?t=2254 




> Quote:
> Since there was no way to get a true reading for the superchunks method in the calculator



True. It's in a corner and separated from other things, whereas the calculator assumes it's infinite surface area.



> Quote:
> I could only look at differences between 4", 8" and 12". The difference was VERY apparent as the material got thicker. At 12" the 703 became the better trap than the 705 and MUCH MUCH better than either at 4".



Yep



> Quote:
> All this to say, according to your calculator, given a choice between 703 and 705, when going above 4", the better choice is in fact the 703. (As you stated in your reply. )



Yep. It's not MY calculator. It's Chris Whealy's. (He had a temporary hosting company problem, so I'm hosting his website on mine for a month or so.)



> Quote:
> However, since there really is very little empirical data for various methods of chunk formation



Personnally I'd just trust the acousticians who discovered it. And remember that corner chunks are probably incompatable with DE style absorbtion.


> Quote:
> I will probably have to resort to multiple in-home tests to figure which is best.



I gave that a try once. I don't have any conclusions, nor a lot of confidence in my results, but here's what I did.
http://www.bobgolds.com/CornerTrap/20040627/home.htm 
http://www.bobgolds.com/CornerTrap/20040627/table.htm 
http://www.bobgolds.com/CornerTrap/20040627/compare.htm


----------



## Stima




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> And remember that corner chunks are probably incompatable with DE style absorbtion.










WHAT!?!? Why is this? Do the corner chunks generally push the room past optimum absorption? If this is the case, can it be countered by using one sheet with FSK as a face for the chunk? (FSK facing into room.)


----------



## BasementBob

Stima:


My thinking (without measurements, so take this with a grain of salt) on corner absorbers vs DE Style absorbtion is that

a) DE style is (front wall fully absorbed, carpet, side walls and rear wall 50% thin absorbtion on lower half of walls, porous absorbtion in soffets and membrane absorbtion in columns, leather seats)

b) studiotips corner absorbers require space around them to work as predicted. (edge effect - read Eric Desart's PlayingWithBaffles.doc)


So, if you put studiotips corner absorbers in the front vertical corners, they'd be touching the fully absorbed front wall. Simiarly on the rear vertical corners they'd be touching the lower 50% absorbed walls. This ruins the edge-effect LF absorbtion boost.

The DE soffets are separated from this wall of absorbtion, so they may already be corner trap-ish (ceiling/wall corner).


It's not that DE style treatment absorbtion turns corner traps into thin HF traps, but just that corner traps change. I'm not sure how significant the change would be.


FSK doesn't change any of my concerns.

I'd use FSK if I were overabsorbed in HF -- and for nothing else.

I'd try to design a room without FSK.


I define "DE Style" as above, includes DIY.

I define "DE Designed" to include about a hundred other criteria done by Dennis's company, including ray tracing of the sound.


I believe that Ethan Winer's "I have 38 traps in my 25 by 16 living room home theater," doesn't suffer from this, because his traps are placed with space between them (bare gypsum/drywall), and not against a 16'x8' wall of absorbtion.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Stima:
> 
> 
> My thinking (without measurements, so take this with a grain of salt) on corner absorbers vs DE Style absorbtion is that
> 
> a) DE style is (front wall fully absorbed, carpet, side walls and rear wall 50% thin absorbtion on lower half of walls, porous absorbtion in soffets and membrane absorbtion in columns, leather seats)
> 
> b) studiotips corner absorbers require space around them to work as predicted. (edge effect - read Eric Desart's PlayingWithBaffles.doc)
> 
> 
> So, if you put studiotips corner absorbers in the front vertical corners, they'd be touching the fully absorbed front wall. Simiarly on the rear vertical corners they'd be touching the lower 50% absorbed walls. This ruins the edge-effect LF absorbtion boost.



[Mr. Bill]Oooh, nooo![/Mr. Bill] My front - behind a false wall - is lined with 2" J-M Linacoustic. Front ceiling has a 4'x8'x2" OC SelectSound panel. L&R front walls a 4'x4' OC SelectSound Panel. Rear wall a 2'x8' of same. Thin carpet all around up to chair rail. Wood floors. Plaster walls and ceiling. Six LaZBoys. Room 13'x21'x8' (nominal-slightly canted walls and ceiling). My plan is (was?) to place 24" face SSCs both corners and ceiling/wall behind false wall and ceiling/wall in rear, and maybe 4' SSCs above 4'x4' L&R panels. I "assumed" the ones lying against the Linacoustic would be enhanced by it. Your post seems to be telling me not only won't it be enhanced, it will be less effective. Right?


----------



## Bookhouseboy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Books,
> 
> 
> > after reading your conlcusion, I wonder if I maybe should go for a higher number of traps.


----------



## Bookhouseboy

Ethan:

Your HT is only a little bigger than mine, and you have 38 traps!? I must say that I'm impressed, because I can't see how I would fit a number close to 38 in my HT.


They must be all over the place!


----------



## BasementBob

pepar:


Studiotips superchunks work best isolated. If you have no other treatment in the room, superchunks are perfect.


Putting them up against a bunch of other absorbtion reduces the edge effect boost, but

a) they're still deep absorbtion (good)

b) they're still in corners (all modes active in tri-corners, good)


----------



## BasementBob

Bookhouseboy


There's a picture of what I think is Ethan's HT on the bottom left of this page
http://www.realtraps.com/placing_mt.htm 

There's 16 out of 38 shown in that picture.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Bookhouseboy
> 
> 
> There's a picture of what I think is Ethan's HT on the bottom left of this page
> http://www.realtraps.com/placing_mt.htm
> 
> There's 16 out of 38 shown in that picture.



Yea, my wife would go for that . . . if she were blind.










(No offense, Ethan!)


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> pepar:
> 
> 
> Studiotips superchunks work best isolated. If you have no other treatment in the room, superchunks are perfect.
> 
> 
> Putting them up against a bunch of other absorbtion reduces the edge effect boost, but
> 
> a) they're still deep absorbtion (good)
> 
> b) they're still in corners (all modes active in tri-corners, good)



Thank you.


----------



## Bookhouseboy

Thanks for the link, BasementBob.


That actully doesn't look half bad considering the amount of traps. The color and finish matches the walls and ceiling, so I think it looks pretty good. But If I were to sell the house, I would probably take them out before showing the room to the potentional buyers.


----------



## Ethan Winer

Bob:


> I believe that Ethan Winer's "I have 38 traps in my 25 by 16 living room home theater," doesn't suffer from this, because his traps are placed with space between them (bare gypsum/drywall), and not against a 16'x8' wall of absorbtion.


----------



## myfipie




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Bob:
> 
> 
> > I believe that Ethan Winer's "I have 38 traps in my 25 by 16 living room home theater," doesn't suffer from this, because his traps are placed with space between them (bare gypsum/drywall), and not against a 16'x8' wall of absorbtion.


----------



## Ethan Winer

Glenn,


> really you don't need that many ... the first 8 made the BIGGEST difference.


----------



## Stima

So Ethan,


In your opinion, will the "chunk" style bass trap work when placed against mid\\hf freq absorption?


More to the point: Do you have any opinion or testing to show the affects of chunk style traps when used in a theater treated using via Dennis Erskine style of absorption? (Full front and side walls up to 1st reflection, then 50% remaining walls.)


NO OFFENSE BOB! Just always like to get more of a consensus opinion.


----------



## Petrucci

What is the best software to measure RT60 ?? I have read a fww places on this thread that it can be bought off the shelf. What are the majority of folks using here ?


----------



## pepar




> Quote:
> Originally Posted by *Petrucci* /forum/post/0
> 
> 
> What is the best software to measure RT60 ?? I have read a fww places on this thread that it can be bought off the shelf. What are the majority of folks using here ?



That's true, but it can also be free .


----------



## BasementBob

Ethan:


> Quote:
> I don't understand how a bass trap is affected at mid/high frequencies depending on what else the traps are touching. Or is that not what you meant?



I think that's backwards.


The edge effect quote that I'm most fond of is


> Quote:
> from: Proceedings of Noise Con 90, David A. Nelson, P.E., INCE Bd. Cert
> 
> The discontinuity in the wave field at the edge of the specimen create a diffraction effect that warps the sound field to make the specimen appear as much as a quarter-wavelength larger in each direction. This increases the sound absorption coefficient to such a degree that it often exceeds the theoretical limit of 1.00.



So, to re-write what you wrote

- A bass trap is NOT affected at high frequencies by what else the traps are touching.

- A bass trap is affected at low frequencies by what else the traps are touching.


But those two lines are also misleading.

The quote by David A. Nelson is much more predictive, and is the best definition of "edge effect" that I've seen.

For example, it's not so much that "touching" is the criteria, but rather proximity relative to wavelength.


Certainly an absorber's contribution to the change in the sound of the room is dependant on the contents of the room. That includes how the absorber is placed (corner, spacing from the wall, proximity to other absorbers, sound paths, etc), and how much absorbtion is in the room (moving from 5% room-surfaces coverage to 15% coverage will have a dramatic effect, whereas moving from 85% coverage to 95% coverage won't be perceptable, even though it's the same volume-and-surface of additional absorbtion product).


Just looking at your HT I can see lots of reasons why you could have a good RT60. I'd bet you have a good sweet spot too. I'm not so sure you have a good sweet _area_ (which DE Designs do).


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> The edge effect quote that I'm most fond of is:
> 
> 
> "The discontinuity in the wave field at the edge of the specimen create a diffraction effect that warps the sound field to make the specimen appear as much as a quarter-wavelength larger in each direction. This increases the sound absorption coefficient to such a degree that it often exceeds the theoretical limit of 1.00."



Should I seek therapy if that makes perfect sense?


----------



## Ethan Winer

Stima,


> Do you have any opinion or testing to show the affects of chunk style traps when used in a theater treated using via Dennis Erskine style of absorption?


----------



## Ethan Winer

Bob,


> I think that's backwards. 
That includes how the absorber is placed (corner, spacing from the wall, proximity to other absorbers, sound paths, etc)


----------



## Bookhouseboy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> But man oh man, those last 34 really add the crowning touch.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



That had me laughing out loud. The first four traps were most important, but the last 34 did the finishing touch.


----------



## BasementBob

Ethan:



> Quote:
> To me that could either be diffraction (probably irrelevant at 80 Hz)



Nope.

There's data from Cath. Univ. Leuven showing as much as a 160% boost due to edge effect at 80hz.



> Quote:
> having a panel's edge surface exposed which simply increases the total surface area.



Nope.

All "edges" have to have length.

But the above quote is true for "edges" that have no area.

A 2'x4'x4" absorber placed on the floor has an edge length of 12', and an edge surface area of 4 ft^2. (Your Number's Game stuff)

A 24" diagonal corner trap in an 8' vertical corner has an edge length of 20', and an edge surface area of 0 (zero) ft^2.

In both cases it's irrelivent for the edge effect how big the edge surface *area* is.

Only the location of the edge, and the surface area of the sample, and the proximity to other samples.


----------



## BasementBob

Ethan:

Do you have any more pictures of your room on the www than the one that I found? (front, sides)


----------



## Stima




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Stima,
> 
> 
> > Do you have any opinion or testing to show the affects of chunk style traps when used in a theater treated using via Dennis Erskine style of absorption?


----------



## BasementBob

Stima:


I don't know how corner traps will perform when placed between and against walls full of absorbtion. I just think it'll be different than any corner measurement data we have.


I remember looking for diagonal corner traps in Dennis' gallaries once, but didn't find any. So I guessed he solved the same problem (bass absorbtion) in another way, a way that combined well with other acoustical/asthetical issues for the listeners.
http://www.designcinema.com/galleries.html 

You could search for Dennis's posts on corner traps in the archives.



> Quote:
> so it's NOT the surface area...but the EDGE area!



It's not the area at all. It's the proximity of the edges. If they're touching there's no edge at all. Corner traps should behave as predicted if the separation to the nearest absorber is greater than 1/4 wavelength.


----------



## sastre

[/quote]Hmmmm....now I have two differing opinions on bass traps next to Mid\\HF absorption.


> After countless hours of reading, I have a high level of respect for the opinions of both Ethan and Bob.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have planned on doing a DE style treatment with some sort of bass trapping. I have been considering "chunk style".(and still am)
> 
> 
> What are the opinions of a Jon Risch DIY bass trap(I guess thats the proper name) found here ?
> 
> Or these ?
> 
> 
> I was thinking of putting them behind a false wall in the L&R corners. Maybe stack them two high.


----------



## jandawil

Question for everyone. I am thoroughly enjoying my new HT and have tried to follow a lot of the great advise in this thread. One issue though. I used to listen to music in Pure Direct on my receiver (Yamaha RX-V2600 with Axiom M80 speakers) and in my untreated living room it sounded fantastic. I have regular plain ol'walls of course and wood flooring with a rug so it is a pretty live room. In my theater it sounds too muddy and compressed in Pure Direct. My back wall is dead with 1" linacousic and I also have carpet and I'm sure that's why. Is this a compromise I will have to live with if I primarily want it to sound good for movies? I am currently listening to music in 7 channel stereo on the Yamaha and it sounds wonderful, but I do miss that Pure Direct a little. Any thoughts???


----------



## Ethan Winer

Bob,


> There's data from Cath. Univ. Leuven showing as much as a 160% boost due to edge effect at 80hz. 
A 2'x4'x4" absorber placed on the floor has an edge length of 12', and an edge surface area of 4 ft^2. (Your Number's Game stuff)


----------



## Ethan Winer

Jon,


> In my theater it sounds too muddy and compressed in Pure Direct. 
My back wall is dead with 1" linacousic and I also have carpet


----------



## jandawil




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Jon,
> 
> 
> > In my theater it sounds too muddy and compressed in Pure Direct.
> My back wall is dead with 1" linacousic and I also have carpet


----------



## Bookhouseboy

Hmm, I was set on buying 6" rockwool acoustic panels to use as bass traps in the five corners of my HT, but the representative for the company recommended to start with 2" panels and then add an extra panel if I didn't get the results I wanted. The first reflection points on the left and right wall, ceiling and some of the rear wall is treated with 1" panels that absorbs down to 500hz. He meant that using 6" panels as bass traps could make the room to dead.


So should I listen to his advice, or should I go for my initial plan?


I know I'm asking questions about things that are elementary, but I just want to make sure before ordering the panels. Please be overbearing.


----------



## Ethan Winer

Jon,


> I also have a very large bass trap in the front corner


----------



## Ethan Winer

Boy (doesn't anyone use names here?),


> the representative for the company recommended to start with 2" panels 
He meant that using 6" panels as bass traps could make the room to dead.


----------



## Bookhouseboy

Ethan,


"Boy (doesn't anyone use names here?)"


I know my nick is kinda long, so just use Boy for short.


"Listen to us, not him. Really. This is a big problem I see all the time. Just because someone sells acoustic materials doesn't mean they automatically know how best to use them."


Yeah, I was thinking that when I spoke to him. I'm ordering twelve 6" panels tomorrow. I can't wait to do a frequency measurement after installing the traps.


"Always glad to oblige!"


Thanks. It's a great thing when professionals take their time to answer questions from beginners on the Internet, wether the subject is gardening or rocket science. It makes me believe in the more positive aspects of the Internet, such as communicating with people from all over the world and sharing useful information.


----------



## jandawil




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Jon,
> 
> 
> > I also have a very large bass trap in the front corner


----------



## bpape

I'd agree. For bass control, 2" is basically worthless unless you have a TON of it. To straddle corners, you'll want AT LEAST 4" - 6" is better if you want to get some bass control.


Bryan


----------



## Bookhouseboy




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> I'd agree. For bass control, 2" is basically worthless unless you have a TON of it. To straddle corners, you'll want AT LEAST 4" - 6" is better if you want to get some bass control.
> 
> 
> Bryan



I'm glad to hear that 6" is a good number. Is it ambitious to think that 6" rockwool panels will absorb as low as 50-60 hz? I know it depends on placement and so forth, but I would like to know the general effect these kind of corner traps have.


----------



## bpape

Is it realistic to expect 6" of mineral wool to absorb down to 50-60hz? Not at all. Is it unrealistic to expect it to have a 1.0 absorbtion coefficient at 50hz? Yeah - probably. It'll still do a good job though.


IMO, 50hz is getting down toward the bottom of what you can effectively deal with via velocity absorbers (unless you have the luxury of building some 2-3' deep absorber recesses in the corner of your room - which some people do). You can still have some effect below that but not of the magnitude that you can above it.


----------



## myfipie

I agree with Bryan. Bass traps with help down to 40hz, but remember I am using the word "help" not solve.


Glenn


----------



## Bookhouseboy

Thanks for the information guys. It's comforting to know that the traps will have a positive effect on the lowest frequencies. I'm not expecting a perfect frequency response, but I'm hoping for a good starting point. The biggest problem in my HT is a terrible dip around 30hz, but I'm gonna buy another sub that I'm sure will cure this problem. I guess HT is a never ending hobby.


I've now ordered 12 x 6" panels, and I'll post results when they are finished, if that's of interest.


----------



## Ethan Winer

Jon,


> It is 14" X 22" X 8'. I will put one more in the other corner and probably two more in the back corners as well. Do you think this will "brighten' up my music any????


----------



## Ethan Winer

Books,


> It's a great thing when professionals take their time to answer questions from beginners on the Internet


----------



## BasementBob

bpape


> Quote:
> IMO, 50hz is getting down toward the bottom of what you can effectively deal with via velocity absorbers (unless you have the luxury of building some 2-3' deep absorber recesses in the corner of your room - which some people do).



I'm considering doing my entire front wall with 2.5' of fluffy. Haven't worked it out yet though. I note that I've NEVER seen a HT like that.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> bpape
> 
> I'm considering doing my entire front wall with 2.5' of fluffy. Haven't worked it out yet though.


 FYI


----------



## BasementBob

pepar:

As near as I can tell from your link, you have 1" of linacoustic there (including a nice speaker cutout).

I'm talking about having 30" of fluffy fiberglass pink.


----------



## Kevin12586




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Jon,
> 
> 
> 
> 
> In my opinion, a 22 by 14 foot room needs at least 8 bass traps, and even twice that is not too many. I wouldn't say it will brighten up your room per se because bass traps are supposed to affect mainly the bass range. Some bass traps absorb the full range, and that type might take you in the wrong direction. But generally speaking, once the bass is tamed the mids and highs _by contrast_ will improve.
> 
> 
> --Ethan



If we are supposed to put one bass trap per corner in a room, how do we fit 8 in a square room? Are you saying to treat other areas besides corners with bass trapping?


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> pepar:
> 
> As near as I can tell from your link, you have 1" of linacoustic there (including a nice speaker cutout).
> 
> I'm talking about having 30" of fluffy fiberglass pink.



Well, it's 2", but I thought your post said "2.5". 30" - whoaaa!


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If we are supposed to put one bass trap per corner in a room, how do we fit 8 in a square room? Are you saying to treat other areas besides corners with bass trapping?



I had the same concerns and am going the StudioTips SuperChunk route with the 24" stack face. I have a novel idea to mount and cover them. I do not have a Taj Mahal, but I still have aesthetic concerns. Realistically, I am a few weeks away from completion, but I will try to take (meaningful) before and after measurements.


----------



## jandawil




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If we are supposed to put one bass trap per corner in a room, how do we fit 8 in a square room? Are you saying to treat other areas besides corners with bass trapping?



I do know corners can also mean where wall and ceiling meet, not just 2 walls. I need to find a good way to implement more traps and still have the room look nice. Thanks Ethan for your help. I think part of my issue may be the speakers are too close to the back wall and thus can't breath. My description of the sound was "muddy", but I don't think that is entirely accurate. Restricted may be a better term. I'll try to move them out (if there is room) and see if that helps.


----------



## jbaracelona

Help,

After treating my room with 3, 2x4x8' 3-4" thick panels, 2 in the front and one corner wall in the rear. 5 wall panels, 3, 2x4x4' 3-4" thick on the right wall, 2 on the rear wall, and 2 covering 36" square windows on the rear wall also. I use 703 on the walls, 3" from the wall, and in the windows, and 705 in the corners.

I have peaks from fq. 28 to 40 to 95 db. The nulls are 75 db between 80 and 90, and fq. 225 to 250 are from 75 to 65 db.

Prior to treatment, the peak from 28 to 40 was only 87. The nulls at fq. 75 to 90 were 65 db, 100 to 120 to 67 db, and 180 to 200 were 73 db.

I mixed the wall panels, two with the paper to the front, bass, and two others with the paper to the rear, one had no paper, front or back.

The room which was live and has toned down and it does take more amp. too get the same loudness from the speakers, but I don't see how I could've increased the peak in lower bass.

Placing the sub in the front left position did help some, but it is not practical because it would be in a walk way. The sub. is behind the sofa and against the rear wall. The room is app. 17x25, but a curtain separates the listening and viewing area from another part of the room at 14'. Listening area is 17x14', setting at 14' from the speakers.

I do have pictures of the room, but don't know how post them on this site. I have read Ethans material and this thread. Thanks if you can help.


----------



## Ethan Winer

Jon & Kevin,


> corners can also mean where wall and ceiling meet, not just 2 walls. 
I think part of my issue may be the speakers are too close to the back wall and thus can't breath.


----------



## jandawil




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Jon & Kevin,
> 
> 
> > corners can also mean where wall and ceiling meet, not just 2 walls.
> I think part of my issue may be the speakers are too close to the back wall and thus can't breath.


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/0
> 
> 
> That's interesting. I think I'll wait to get my additional traps in and than mess with it. I did move the speakers out about 4" and the bass did improve, but my speakers are flanked on the outsides by a wall on one side of the room and my AV rack on the other. Nothing I can do about that unless I go with an acoustical transparent screen and that's not in the plans. 2 channel stereo sounds wonderful now because the crossover kicks in at 80Hz and my SW takes care of the lows. No more tweaking until the additional traps are in.



Yes, at some point practical and aesthetic concerns trump ideal speaker/sub placement. At that point, treatments and EQ are all that's left to employ.


----------



## MBK

I've got a slightly odd situation I'm hoping I can get some advice on.


I live in a loft, with some rooms carved out of it. None of the walls go to the ceiling, so think overgrown cubicles. The ceiling is 12' high, the walls go to about 8.5'.


I'm enclosing a shot of the floorplan for the theater (a bad scan). As you can see, it's a somewhat odd shape (being in NYC real estate is always a compromise). The distance from the back of the couch to the screen is about 13'. It's all worked out quite nicely, but I'm sure it would be even better if I could cut down on a bit of the liveness. We've put carpet down which helped quite a bit, but I'm wondering what the best method to tame the remaining reverb is.


Any suggestions?


----------



## pepar




> Quote:
> Originally Posted by *MBK* /forum/post/0
> 
> 
> I've got a slightly odd situation I'm hoping I can get some advice on.
> 
> 
> I live in a loft, with some rooms carved out of it. None of the walls go to the ceiling, so think overgrown cubicles. The ceiling is 12' high, the walls go to about 8.5'.
> 
> 
> I'm enclosing a shot of the floorplan for the theater (a bad scan). As you can see, it's a somewhat odd shape (being in NYC real estate is always a compromise). The distance from the back of the couch to the screen is about 13'. It's all worked out quite nicely, but I'm sure it would be even better if I could cut down on a bit of the liveness. We've put carpet down which helped quite a bit, but I'm wondering what the best method to tame the remaining reverb is.
> 
> 
> Any suggestions?



None of the walls going to the ceiling sounds like the entire loft area outside of your theater is the culprit. If so, treatment is needed there.


----------



## MBK

No, the reverb is definitely more evident in the theater. Anywhere else in the apartment you don't hear it. Probably because there are enough soft surfaces (furniture, lots of books in shelves, etc.). In the theater it's very spare, really just the screen and the couch. I had a setup in the same location before the walls went up and reverb wasn't much of an issue because things were so open. With the new walls the inside of the theater is a much more "live" space.


----------



## Stima




> Quote:
> Originally Posted by *MBK* /forum/post/0
> 
> 
> No, the reverb is definitely more evident in the theater. Anywhere else in the apartment you don't hear it. Probably because there are enough soft surfaces (furniture, lots of books in shelves, etc.). In the theater it's very spare, really just the screen and the couch. I had a setup in the same location before the walls went up and reverb wasn't much of an issue because things were so open. With the new walls the inside of the theater is a much more "live" space.




Then you have solved your own problem!







If the walls have screwed up your sound field...which it appears you now have 1st reflections to deal with when before you didn't....you now need to treat those walls with some absorption. Find your first reflection points using the simple light and mirror trick. Once you find them, threat those areas with absorption panels. This should do the trick.


----------



## MBK

Thanks Stima, I figured it would be something like that but wanted to check with the collective brain and make sure that there was nothing else I was missing there. I'm guessing I should be able to do it with a few panels on each side and behind the speakers.


----------



## pepar




> Quote:
> Originally Posted by *MBK* /forum/post/0
> 
> 
> Thanks Stima, I figured it would be something like that but wanted to check with the collective brain and make sure that there was nothing else I was missing there. I'm guessing I should be able to do it with a few panels on each side and behind the speakers.



You should also consider the ceiling, floor and, many times overlooked, the back wall.


----------



## MUCHO

Can someone tell me about why you have to be able to breathe through the cloth to use it?


I just built some panels, 2 bass traps and 3 panels that will hang on the walls to absorb some of the mids/highs.


The cloth I used I couldn't blow through - but I used it anyways. Did I waste my time? All the cloth I found I could blow through I could see through to some extent and since the panels are supposed to be black I wanted them black. (Err I mean wife wanted them black







)


----------



## bpape

If you can't breathe through it much at all, you'll change the absorbtion characteristics as the fabric will act somewhat like a membrane. For the mid/high reflection absorbers, this is a non-starter.


A good quality fabric like GOM will still appear black but is easy to blow through. If you need more 'blackness', you an put a layer of dyed muslin or burlap behind it to add some more darkness without restricting the airflow.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *MUCHO* /forum/post/0
> 
> 
> Can someone tell me about why you have to be able to breathe through the cloth to use it?
> 
> 
> I just built some panels, 2 bass traps and 3 panels that will hang on the walls to absorb some of the mids/highs.
> 
> 
> The cloth I used I couldn't blow through - but I used it anyways. Did I waste my time? All the cloth I found I could blow through I could see through to some extent and since the panels are supposed to be black I wanted them black. (Err I mean wife wanted them black
> 
> 
> 
> 
> 
> 
> 
> )



Bryan's nailed it; if you can't breathe through it, air molecules don't pass through it, and if air molecules don't pass through it, sound waves won't pass through it.


----------



## Kevin12586




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Jon & Kevin,
> 
> 
> > corners can also mean where wall and ceiling meet, not just 2 walls.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If #2, how to determine which tri corners and which wall/ceiling corners to treat. I was all set to just treat all my tri corners until I read this statement and now I am unsure.
> 
> [/url] is the layout of my basement.




I looked at your layout to see what the room dimentions are and it isn't clear. You show a side wall that is offset and split? The reason I'm asking is that it is my understanding that when you are deciding which walls/corners to treat (other than first and second reflection points) you should go with the walls causing the most problems with the sound. You can use a "mode" calculator to tell you which walls are causing the most problems due to the size of the room.


I'm sure one of the other guys can give you detailed instructions on how to go about this much better than I can.


----------



## Kevin12586

All of the dimensions are on the drawing (except for the far right wall which is 31'9"). As for the offset, use the inner portion, the outer portion is just where the concrete wall is in reference to my drywall.


Where can I find this 'mode' calculator that you mention?


----------



## myfipie




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> If you had to choose, and you are limited with how many panels you can install, which would be a better solution:
> 
> 
> 1. Treat all tri corners (where wall/wall/ceiling meet) with bass trapping?
> 
> 
> 2. Treat some tri corners and some wall/ceiling corners with bass trapping?
> 
> 
> If #2, how to determine which tri corners and which wall/ceiling corners to treat. I was all set to just treat all my tri corners until I read this statement and now I am unsure.
> 
> 
> I am buying 20-2'x4' panels and I have to treat my open basement with those. This includes hitting the first reflection points from my front speakers on the side walls, putting panels on my screen wall, bass trapping in all tri corners (unless I am told otherwise) putting a panel in the staircase due to the 2 parallel walls (the basement space is completely open so sound in the theater should be affected by the sound heading up the staircase) and depending on how many panels I have left, treat the ceiling for FRP.
> 
> Here is the layout of my basement.



To do the job right I would start with bass traps floor to ceiling in the front corners and then focus on ceiling to wall or floor to wall corners.


Glenn


----------



## Kevin12586




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> To do the job right I would start with bass traps floor to ceiling in the front corners and then focus on ceiling to wall or floor to wall corners.
> 
> 
> Glenn



So I should start with bass traps in the front corners then the wall/ceiling corners? So not 'all' the tri-corners need to be addressed since I am limited?


If you look at the plans, the red lines running from left to right are support beams that run across the ceiling, they are about 6" in height and form a tri-corner when they reach a wall, I was planning to put bass traps there as well, do you agree?


Counting the tri-corners that are formed by the support beams, how many tri-corners would you recommend be treated?


----------



## Dan Woodruff




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> All of the dimensions are on the drawing (except for the far right wall which is 31'9"). As for the offset, use the inner portion, the outer portion is just where the concrete wall is in reference to my drywall.
> 
> 
> Where can I find this 'mode' calculator that you mention?



It doesn't show ceiling height, unless it's there and I missed it.


----------



## Ethan Winer

Kevin,


> If you had to choose, and you are limited with how many panels you can install, which would be a better solution:


----------



## MUCHO




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Bryan's nailed it; if you can't breathe through it, air molecules don't pass through it, and if air molecules don't pass through it, sound waves won't pass through it.



Well - don't take this the wrong way - but it sounds like conventional wisdom. Considering the work and $$$ it will take me to redo my absorbers I want to make sure this is accurate.


I guess what I'm saying is, are you certain this is true?


Certainly I could put up a wall of this cloth and hold a conversation through it.


Any tests been done on this type of thing?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Bryan's nailed it; if you can't breathe through it, air molecules don't pass through it, and if air molecules don't pass through it, sound waves won't pass through it.



Air molecules don't need to pass through it. They just need to vibrate it to transmit sound waves.


Regards,

Terry


----------



## pepar




> Quote:
> Originally Posted by *MUCHO* /forum/post/0
> 
> 
> Well - don't take this the wrong way - but it sounds like conventional wisdom. Considering the work and $$$ it will take me to redo my absorbers I want to make sure this is accurate.
> 
> 
> I guess what I'm saying is, are you certain this is true?
> 
> 
> Certainly I could put up a wall of this cloth and hold a conversation through it.
> 
> 
> Any tests been done on this type of thing?



And don't you take this the wrong way either. Before you spent the $$$ and did all the work, did you research building absorbers?


To use your example, the metric is not that you can carry on a conversation through it, but that your voices sounds the same with the cloth between you and the other conversant as they do without.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Air molecules don't need to pass through it. They just need to vibrate it to transmit sound waves.
> 
> 
> Regards,
> 
> Terry



Wouldn't the air molecules need to be touching each other to pass the energy along losslessly? Otherwise the cloth gets involved in the transaction and then it's characteristics come into play.


----------



## MUCHO




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> And don't you take this the wrong way either. Before you spent the $$$ and did all the work, did you research building absorbers?
> 
> 
> To use your example, the metric is not that you can carry on a conversation through it, but that your voices sounds the same with the cloth between you and the other conversant as they do without.



Don't worry I'm not sensative at all. I did lots of research and everything I read said I should buy cloth I could blow through. I just didn't.










I haven't yet hung them up on the wall and now I'm having second doubts about my decision to use a cloth weave I couldn't blow through.


I'm simply trying to find an accurate answer to my question - by someone who knows based on fact and data not conventional wisdom. If you're the guy who knows - then you're the guy. I'm just the guy asking questions!


If I have to go back to the store, spend a couple bucks, and redo the coverings - so be it. I'm just trying to avoid it.


But based on your logic - are you saying the voice would sound the same through a cloth wall I could breath through?


----------



## Kevin12586




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/0
> 
> 
> It doesn't show ceiling height, unless it's there and I missed it.



Sorry, the ceiling is 7.5' high, I didn't realize you wanted that dimension as well.




> Quote:
> That drawing doesn't show where the speakers and listener will be, so it's impossible to say what traps will be best where. But even if you had included that on the drawing, it's still impossible to predict. As Glenn said, for bass trapping you treat as many corners as possible, especially in the front, using rigid fiberglass at least four inches thick.



The left speaker is 6" off the left wall, the center will be located above the screen and the right speaker is parallel to the left. Both left/rights speakers are 2 feet from the front wall. The center is in a window well on the front wall. The front row of seats is 12' from the front wall and 10' from the front speakers.


I understand it is impossible to predict and thank you for your help. Based on what everyone has stated, this is what I am now going to do, please let me know if anyone sees any problems with this:


1. Add bass trapping, at least 4" thick, to all tri-corners (including where the support beams meet the walls to form a tri-corner)

2. Add bass trapping to the front wall, where the wall and ceiling meet

3. Treat all first reflection points for all 3 front speakers from each seat in the theater with 2" panels

4. Treat the front wall with 2" panels

5. Treat behind the screen with 2" panels

6. Put 1 panel in the staircase on one of the 2 parallel walls

7. If I have panels left, treat the FRP on the ceiling


If I have missed anything, please let me know.


Thanks


----------



## pepar




> Quote:
> Originally Posted by *MUCHO* /forum/post/0
> 
> 
> 
> But based on your logic - are you saying the voice would sound the same through a cloth wall I could breath through?



No, while you can blow through acoustically transparent cloth, I'd bet that not all cloth that can be blown through is acoustically transparent. I don't know where to find acoustical data on cloth not being sold as specifically having some partticular usage for that purpose. I imagine others here could though . . .


----------



## MUCHO




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> No, while you can blow through acoustically transparent cloth, I'd bet that not all cloth that can be blown through is acoustically transparent. I don't know where to find acoustical data on cloth not being sold as specifically having some partticular usage for that purpose. I imagine others here could though . . .



Good point.


I await the experts who will tell me I should have just gotten the right cloth the first time around - or not.


----------



## BasementBob

MUCHO:


If you can easily breath through it, then it's acoustically transparent, and the acoustical properties of whatever you put behind it will be the final acoustical properties of it in the room.


But that doesn't mean that you MUST use a covering that you can breath through.


I can't easily breath through the fabric of my shirt, so it will change the absorbtion of the fiberglass behind it if that fabric were used as a cover. Bass will probably still go through it as if it wasn't there. But some frequencies will be reflected some amount. Who knows how much.


Putting a thin light air-tight covering over the fiberglass, such as SaranWrap, will reflect just a bit of highs.


Putting a heavier material, such as a heavy velour curtain, will reflect more frequencies -- but may absorb some on its own too. It might even be six of one and half a dozen of the other.


A heavier still material, such as leather, as you might have on a couch, will reflect sound all the way down to the mid frequences.


Heavier still material, such as drywall, will reflect sound all the way down to the bass frequencies. A 'wall' like this will still absorb something -- but it's so BAD an absorber that it's called a reflector.



Variations on this theme are actually quite useful.

For example, if your RT60 is too low in the HF, but just fine in the LF, you can cover some of your absorbers with something reflective to increase the HF RT60 without changing the LF RT60, such as the FRK or foil etc.

Similarly, if you've got a cloth couch, you can buy a leather couch.


And the knowledge of what happens when you cover things is also useful.

For example, your first reflection point absorbers you probably want to catch all the MF to HF sound (to improve stereo imaging) -- so a cover that's acoustically transparent to take maximum HF use of the absorber fiberglass would be a good thing.


----------



## bpape

Realistically, if the material is breathable easily or even relatively easily, it will work fine for covering treatments and can be considered transparent for that purpose.


For purposes of putting cloth in front of a speaker, that's a whole different story. Even some relatively breathable fabrics - some even by Guilford - are not suitable for this use as they tend to absorb extreme high frequencies by as much as 10db in some cases.


----------



## myfipie




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Realistically, if the material is breathable easily or even relatively easily, it will work fine for covering treatments and can be considered transparent for that purpose.
> 
> 
> For purposes of putting cloth in front of a speaker, that's a whole different story. Even some relatively breathable fabrics - some even by Guilford - are not suitable for this use as they tend to absorb extreme high frequencies by as much as 10db in some cases.



10db???? Is this a guess or do you have data to back that up? That just seems like a lot for a piece of fabric. I guess high frequencies only dogs can hear could be possible.










Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> 10db???? Is this a guess or do you have data to back that up? That just seems like a lot for a piece of fabric. I guess high frequencies only dogs can hear could be possible.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Glenn



Naugahyde?


----------



## bmackrell




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Realistically, if the material is breathable easily or even relatively easily, it will work fine for covering treatments and can be considered transparent for that purpose.
> 
> 
> For purposes of putting cloth in front of a speaker, that's a whole different story. Even some relatively breathable fabrics - some even by Guilford - are not suitable for this use as they tend to absorb extreme high frequencies by as much as 10db in some cases.



Bryan,


In the Guillford fabric line, I found the FR series material to be somewhat coarse and extremely low on the WAF (at least for covering wall treatments). We ordered up a bunch of other samples and settled on several colors from their Anchorage line (can't remember the style number). The material is much smoother, seems "breathable" and meets the WAF. I'm not sure the blow through test helped me determine if this material was suitable to cover the wall treatments. Have you used any of the GOM lines other than the FR701 series?


This has also got me looking at the decision to use something like speaker grill cloth for the front screen wall instead of Black FR701 GOM.


Thoughts?


Regards,


BillMac


----------



## Kevin12586




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Sorry, the ceiling is 7.5' high, I didn't realize you wanted that dimension as well.
> 
> 
> 
> 
> 
> The left speaker is 6" off the left wall, the center will be located above the screen and the right speaker is parallel to the left. Both left/rights speakers are 2 feet from the front wall. The center is in a window well on the front wall. The front row of seats is 12' from the front wall and 10' from the front speakers.
> 
> 
> I understand it is impossible to predict and thank you for your help. Based on what everyone has stated, this is what I am now going to do, please let me know if anyone sees any problems with this:
> 
> 
> 1. Add bass trapping, at least 4" thick, to all tri-corners (including where the support beams meet the walls to form a tri-corner)
> 
> 2. Add bass trapping to the front wall, where the wall and ceiling meet
> 
> 3. Treat all first reflection points for all 3 front speakers from each seat in the theater with 2" panels
> 
> 4. Treat the front wall with 2" panels
> 
> 5. Treat behind the screen with 2" panels
> 
> 6. Put 1 panel in the staircase on one of the 2 parallel walls
> 
> 7. If I have panels left, treat the FRP on the ceiling
> 
> 
> If I have missed anything, please let me know.
> 
> 
> Thanks



No one has any opinions on my plans? At least tell me if this sounds sufficient or if you would make any changes to my plans........all help is appeciated


----------



## MUCHO

Thanks for all the info guys. Really appriciate it. For now I guess I'll take the lazy mans way and go with what I got


----------



## Kevin12586

I have a question about first reflection points. In my basement, the left wall is 6" from the left speaker and 9' from the right speaker, the right wall is 21' from the right speaker and 30' from the left speaker.


Because of the extreme difference in distance distance from the right wall to the listening position, does the right wall need to be treated as well? I ask because I am assuming it will take longer for sound to bounce off the right wall and reach the listener than the left wall, and by the time the sound has reached the listener the brain has already processed what has happened. Am I mistaken?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> I have a question about first reflection points. In my basement, the left wall is 6" from the left speaker and 9' from the right speaker, the right wall is 21' from the right speaker and 30' from the left speaker.
> 
> 
> Because of the extreme difference in distance distance from the right wall to the listening position, does the right wall need to be treated as well? I ask because I am assuming it will take longer for sound to bounce off the right wall and reach the listener than the left wall, and by the time the sound has reached the listener the brain has already processed what has happened. Am I mistaken?



If I were you (and without further ado), I'd treat *all* first reflection points - ceiling, front L&R walls, floor AND back wall) and then add bass traps in the front. And THEN I'd make some acoustical measurements to see if I needed more traps and/or some diffusion. That's what I'd do . . .


----------



## Terry Montlick




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> I have a question about first reflection points. In my basement, the left wall is 6" from the left speaker and 9' from the right speaker, the right wall is 21' from the right speaker and 30' from the left speaker.
> 
> 
> Because of the extreme difference in distance distance from the right wall to the listening position, does the right wall need to be treated as well? I ask because I am assuming it will take longer for sound to bounce off the right wall and reach the listener than the left wall, and by the time the sound has reached the listener the brain has already processed what has happened. Am I mistaken?



If the difference between the direct speaker-to-ear distance and the billiard-shot distance reflecting off the wall is greater than around 15', you are OK. The reflection does not get integrated into the direct sound, and your front sound stage is undisturbed.


Regards,

Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> If the difference between the direct speaker-to-ear distance and the billiard-shot distance reflecting off the wall is greater than around 15', you are OK. The reflection does not get integrated into the direct sound, and your front sound stage is undisturbed.
> 
> 
> Regards,
> 
> Terry



Still, with all that space, he may still need to put some absorption on that wall, right?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Still, with all that space, he may still need to put some absorption on that wall, right?



Sure. Depends upon the reverberation times of the room, but typical home theaters need *lots* of wideband absorption.


- Terry


----------



## Ethan Winer

Terry,


> typical home theaters need *lots* of wideband absorption.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry,
> 
> 
> > typical home theaters need *lots* of wideband absorption.


----------



## myfipie




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> I just measure reverb times and adjust them, using acoustical treatment, to where they should be!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> - Terry



Glad to see you are coming around to the right way of thinking...














I am just kidding Terry don't flame me..


Glenn


----------



## bpape

Bill,


IIRC, the Anchorage is one of the worst acoustical performers in the Guilford line. However, most of that issue is due to HF attenuation. For walls in front of soft broadband absorbtion it should be fine - just don't put it in front of speakers.


Bryan


----------



## bmackrell

Right! That's what I figured. Thanks.


----------



## Kevin12586




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Still, with all that space, he may still need to put some absorption on that wall, right?



So it would be best to treat the far wall.


Thanks, I think I _FINALLY_ have a plan to acoustically treat my theater


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> So it would be best to treat the far wall.
> 
> 
> Thanks, I think I _FINALLY_ have a plan to acoustically treat my theater



I'm not sure there's a consensus on treating that wall or if there is, that there's consensus on why. It seems likely you'll need more broadband absorption than what the "other" first reflection point absorbers will provide, but Terry's point of the wall being so far away so as not to cause an "early" reflection is a good one.


I recommend that you should get some acoustical testing software, a decent microphone and take some measurements. If that sounds daunting, bear in mind that it's pretty much the only way to know what you really need beyond those first reflection points. And it's not really that daunting once you get into it.


----------



## Kevin12586

Any advice on good acoustical testing software?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Any advice on good acoustical testing software?


 Room EQ Wizard is a good one, and it's free. And I use the calibrated mic from ETF Acoustics which is excellent, but far from free. Perhaps someone else here can point you to a lesser expensive mic that will still do the job.


----------



## KERMIE

New to this but there is great info from everyone.


I have a question of the "Front Wall"


I have an existing wall from previous owner that is insulated. I have built and Wall inside of that and that is where I am at.


I have read many things on the "Front Wall" and that it should be "Dead"


My question is this (2 fold) (More concerned with "in room" acoustics then sound transmission thorughout the rest of the house.


To make the wall better for acoustics should I:


a. Fill with 3.5 inch "acoustical Cotton Bats that I have, ,put a layer of 1" Linacoustic over the whole thing including the face of the studs. Then cover the wall with GOM?


or



b. Fill with 3.5 inch "Acoustical cotton bats that I have, then Drywall, then 1" Linacoustic, Then GOM.



c. do "a" or "b" on the bottom half of the wall only.


Not sure if "a" will make the wall or room too dead.


Need a little expert advice.


thank you,


----------



## Stima

You may need to clarify what you are trying to do here.


Where do you want your front speakers to be located? In front of the new wall, mounted flush in the wall, behind the wall\\screen like at a theater?


----------



## KERMIE

actually the speakers will be in front of the new wall or attached to the new wall.


there is not enough depth to put the speakers into the wall.


basically the original wall was crooked and done rather poorly, in has drywall on it and standard insulation behind it.


We built a new wall 1" decoupled from the original wall just to level it out and make it square. It is open for whatever I need to do acoustically.


hope that helps.


----------



## KERMIE

Basically, my question is since there is an existing wall with Drywall on it. Can I fill the new wall with insulation and cover with GOM? or do I need to Drywall the new wall on the side facing the viewing area? (then have to treat that)


thank you for your help.


----------



## Terry Montlick




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> To make the wall better for acoustics should I:
> 
> 
> a. Fill with 3.5 inch "acoustical Cotton Bats that I have, ,put a layer of 1" Linacoustic over the whole thing including the face of the studs. Then cover the wall with GOM?
> 
> 
> or
> 
> 
> b. Fill with 3.5 inch "Acoustical cotton bats that I have, then Drywall, then 1" Linacoustic, Then GOM.



"a" will give you some pretty good bass absorption on the front wall. "b" won't. It depends on what the room needs. But extra bass absorption is generally a very desirable thing, especially since you can add it invisibly and with little trouble or expense.


Regards,

Terry


----------



## exipnos




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> My question is this (2 fold) (More concerned with "in room" acoustics then sound transmission thorughout the rest of the house.
> 
> 
> To make the wall better for acoustics should I:
> 
> 
> a. Fill with 3.5 inch "acoustical Cotton Bats that I have, ,put a layer of 1" Linacoustic over the whole thing including the face of the studs. Then cover the wall with GOM?
> 
> 
> or
> 
> 
> 
> b. Fill with 3.5 inch "Acoustical cotton bats that I have, then Drywall, then 1" Linacoustic, Then GOM.



I'm no expert but after long time researching my HT build this is what I picked up.


You mentioned that acoustics is the issue and not sound insulation. When you are using option b its for sound insulation purposes. You are basically building a double wall which will be very good for sound insulation. Is the wall in question common to the rest of the house?


The way you should look at the issue is how much sound insulation do you need.


If you don't need the sound insulation help from the additional layer of drywall then go with option a. You will then in effect have started your acoustical treatments. But you, still need to figure out what the optimal combination of depth of cotton bats plus linacoustics would be for your room.


Cheers,


Exipnos


----------



## KERMIE

thank you guys for your help.


My room is 14 x 18 x 8


Front wall is the double wall.


Original wall is attached to the frame of the house, the wall I added is not, except where the RSIC clips meet.


When Left wall and Right walls are Linacoustic 1" floor to ceiling about 4 feet out. Both side walls the rest of the 14 feet are Linacoustic 44 inches from floor and dry wall the rest of the way. (plan on using acoustical panels where needed above 44 inches)


back wall is the same as the sides. but may us some diffusers on that if needed.


I will have bass traps 18" diag. floor to ceiling on front wall in both corners, and the back wall a bass trap from the floor up to 44" (Chair Rail Height) in both corners. Then a small bass trap in the upper corners of back wall. (Functional and cosmetic)


I have carpet with 3/8 pad on floor.


Have not thought much about the ceiling yet, there is currently a drop ceiling 2 inches from joist. might have to use some first reflection panel across the ceiling after i get things fired up.


Am I on the right path??


----------



## bpape

In order to help balance things a bit better, use the drop ceiling to your advantage. Plan on filling the gap above the drop with fluffy insulation as well as the joist cavities. This will broaden the absorbtion othe drop ceiling.


----------



## myfipie




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> thank you guys for your help.
> 
> 
> My room is 14 x 18 x 8
> 
> 
> Front wall is the double wall.
> 
> 
> Original wall is attached to the frame of the house, the wall I added is not, except where the RSIC clips meet.
> 
> 
> When Left wall and Right walls are Linacoustic 1" floor to ceiling about 4 feet out. Both side walls the rest of the 14 feet are Linacoustic 44 inches from floor and dry wall the rest of the way. (plan on using acoustical panels where needed above 44 inches)
> 
> 
> back wall is the same as the sides. but may us some diffusers on that if needed.
> 
> 
> I will have bass traps 18" diag. floor to ceiling on front wall in both corners, and the back wall a bass trap from the floor up to 44" (Chair Rail Height) in both corners. Then a small bass trap in the upper corners of back wall. (Functional and cosmetic)
> 
> 
> I have carpet with 3/8 pad on floor.
> 
> 
> Have not thought much about the ceiling yet, there is currently a drop ceiling 2 inches from joist. might have to use some first reflection panel across the ceiling after i get things fired up.
> 
> 
> Am I on the right path??



wow sounds like you have really thought through your room acoustics, hats off to you sir. As Bryan said the fluffy fiberglass above the drop ceiling works great.


Glenn


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> "a" will give you some pretty good bass absorption on the front wall. "b" won't. It depends on what the room needs. But extra bass absorption is generally a very desirable thing, especially since you can add it invisibly and with little trouble or expense.
> 
> 
> Regards,
> 
> Terry



Kermie: My room is 13 x 21 x 8 and it needs a LOT of absorption in the 100Hz-300Hx range. I'd imagine your room will be pretty much the same.


----------



## KERMIE




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> wow sounds like you have really thought through your room acoustics, hats off to you sir. As Bryan said the fluffy fiberglass above the drop ceiling works great.
> 
> 
> Glenn




Thanks to about 2 months of reading this sight prior to starting. There are some great minds on here. I do not have an unlimited budget so I am just doing what I can with what I have.


Great idea about the ceiling. It should not cost much so I will put that on the list.



As far as the "absorption in the 100Hz-300Hx range" what is the best way to go about that. "Acoustical Panels"?



I have a friend that sets up for a local band and he has some good knowledge of sound but he won't be around until July. He said he would come over with some of his computer equipment to help with the location and panels.


Hopefully I will be at that point by then. A few hours here and there, you can't get much done.....lol.


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> Thanks to about 2 months of reading this sight prior to starting. There are some great minds on here. I do not have an unlimited budget so I am just doing what I can with what I have.



The DIY route, after lots of reading - here and everywhere you can find, can produce near-pro results. Certainly results that will have your friends' jaws dropping. And not cost a lot of money. If you can source the raw material and build your own panels, traps, etc., you can spend but a fraction of what some have in their theaters.



> Quote:
> Great idea about the ceiling. It should not cost much . . .



Precisely!



> Quote:
> As far as the "absorption in the 100Hz-300Hx range" what is the best way to go about that. "Acoustical Panels"?


 Bass traps .



> Quote:
> I have a friend that sets up for a local band and he has some good knowledge of sound but he won't be around until July. He said he would come over with some of his computer equipment to help with the location and panels.



Excellent! As close as the "great minds" here can get to diagnosing and prescribing for your theater _from their keyboards_, acoustical testing IN THE ROOM is quite necessary for your theater to be all it can be. And a laptop with a modest amount invested in software and hardware is an economical way to pull the room together acoustically.


----------



## myfipie

>As far as the "absorption in the 100Hz-300Hx range" what is the best way to go about that. "Acoustical Panels"?


----------



## Kevin12586

I have a metal 6 panel fire-proof door at the back of my theater, about 28' from the front wall, should this door be treated?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> I have a metal 6 panel fire-proof door at the back of my theater, about 28' from the front wall, should this door be treated?



What are the walls? Probably, it should be treated however it would be treated if it were a wall - first reflection point and/or as part of an overall absorption/diffusion strategy.


----------



## sri777

sorry if this has already been asked and answered but I havent' come across..


With all this fiberglass packed on all outsides of the room walls, aren't you all concerned about the health hazards? If yes, what care are you taking?



thanks

sri


----------



## pepar




> Quote:
> Originally Posted by *sri777* /forum/post/0
> 
> 
> sorry if this has already been asked and answered but I havent' come across..
> 
> 
> With all this fiberglass packed on all outsides of the room walls, aren't you all concerned about the health hazards? If yes, what care are you taking?



Is this a general question, or asked specifically of one member? All of my fiberglass panels are covered with fabric, I vacuum them every now and then, and our house has a few ion breeze filters.


----------



## Kevin12586




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> What are the walls? Probably, it should be treated however it would be treated if it were a wall - first reflection point and/or as part of an overall absorption/diffusion strategy.




The walls are sheetrock with the first reflection points going to be treated. I will be treating the front wall so now I am looking at the back wall. I will be adding a bar to the rear of my theater, is treatment still recommended back there?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> The walls are sheetrock with the first reflection points going to be treated. I will be treating the front wall so now I am looking at the back wall. I will be adding a bar to the rear of my theater, is treatment still recommended back there?



Well, the back wall is one of the first reflection points (though distance may make it moot). Some go for absorption, others for diffusion. A bar may be diffusive by itself, while bar patrons would be absorptive - and absorbing.







Barring using some sophisticated room modeling software, just built the darn thing and *then* use some simple and relatively inexpensive testing software/hardware to determine what you need beyond first reflection points. Just don't make the bar concave.


Just my $.03.


----------



## Kevin12586

As usual, thanks Pepar


----------



## bpape

If you're out of room (or WAF) and need to deal more with the 100-300Hz range, simply modding your reflection absorbers from 1" to 2" and potentially from 703 to acoustical cotton will provide excellent additional absorbtion in that range without any more loss of wall or floor space.


----------



## Lindahl

Is HF comb filtering on acoustically transparent screens due to interference from reflections between the speaker face and the screen, or is it due to the screen attenuating different HFs by different levels? I'm wondering what, if any, benefits would be had by treating the speaker face with absorpative material.


----------



## pepar




> Quote:
> Originally Posted by *Lindahl* /forum/post/0
> 
> 
> Is HF comb filtering on acoustically transparent screens due to interference from reflections between the speaker face and the screen, or is it due to the screen attenuating different HFs by different levels? I'm wondering what, if any, benefits would be had by treating the speaker face with absorpative material.



The comb filtering is from the sound reflecting from the back of the screen to the face of the speaker and back out through the screen - out of phase, of course, with the direct sound. If you click on my link and navigate to pg 14, you'll see the recommended (by THX) acoustical treatment to minimize the comb filtering. This is present only with microperfed screens; the cloth screens seem to not have the issue. But then, they are at most, only approaching unity gain, where a Stewart, for example, can have gain. Mine is a microperfed Stewart Firehawk, a 1.3-ish screen. Perfing cuts gain by 11%, but that's still a nice gain.


----------



## Dennis Erskine




> Quote:
> This is present only with microperfed screens; the cloth screens seem to not have the issue.



Actually, this is not the case even for the highly touted SR products. It can be heard and can be measured. Both Tony Grimani and I have measured and demonstrated this.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Actually, this is not the case even for the highly touted SR products. It can be heard and can be measured. Both Tony Grimani and I have measured and demonstrated this.










You mean their advertising is false???!!!


edit: Perhaps John Dahl's quote is most accurate; "No screen we've tested to date matches the acoustical transparency . . "


----------



## Dennis Erskine




> Quote:
> "No screen we've tested to date matches the acoustical transparency . . "



...that should be extended to include light transparency as well.


----------



## Lindahl

So Dennis (or anyone else), how effective is placing absorpsion on a speaker face in reducing comb filtering of AT screens? Does it all but eliminate it? Or are the reflective properties of the tweeters and woofers enough to keep a significant portion of the comb filtering intact?


There's been some discussion about it, starting here . Unfortunately, you'll have to weed through some cleverly disguised flames and insults (fluff and sarcasm).


----------



## pepar




> Quote:
> Originally Posted by *Lindahl* /forum/post/0
> 
> 
> So Dennis (or anyone else), how effective is placing absorpsion on a speaker face in reducing comb filtering of AT screens? Does it all but eliminate it? Or are the reflective properties of the tweeters and woofers enough to keep a significant portion of the comb filtering intact?
> 
> 
> There's been some discussion about it, starting here . Unfortunately, you'll have to weed through some cleverly disguised flames and insults (fluff and sarcasm).



The mask and treatment of the cavity behind the speaker mitigates the comb filtering, and the 1/3 octave EQ shapes the sound to compensate for the loss due to getting sound through the little holes, but try as I might, I cannot get the center spkr's sound identical to the L & R spkrs.


Having said that, dialog issuing forth from the actor's mouths is a wonderful thing and I don't think I will ever have any other setup than the center channel behind the screen.


Just my $.03.


----------



## BasementBob

sri777 :



> Quote:
> With all this fiberglass packed on all outsides of the room walls, aren't you all concerned about the health hazards? If yes, what care are you taking?





> Quote:
> Originally Posted by *Rod Gervais* /forum/post/0
> 
> 
> from: http://www.recording.org/ftopict-21013.html
> 
> 
> Folks,
> 
> 
> People have heard all kinds of stories about fiberglass and it's hazzards. It has been stated:
> 
> 
> 
> 
> Quote:
> I mean that cutting fiberglass can be a bit of a health hazard because the fibers, which are a known carcinogen, are released into the air and can be inhaled. Studies have shown that glass fibers from a stationary piece of rigid fiberboard will not be released into the air in significant numbers, especially when the board is covered in fabric, but you should definitely wear gloves and some type of facemask when cutting 705. I'm pretty sure that a paper mask will be enough, but you should definitely double check me on this before you start.
> 
> 
> 
> 
> OK,
> 
> 
> There have been more than a few questions/statements regarding health issue relating to fiberglass in the past few weeks - and tis time to maybe put the "myths" to rest.
> 
> 
> It was reported in the late 80's early 90's about the possibility of fiberglass being a possible carcinogen - and many claims from various sources since then that it actually is.
> 
> 
> However the following comes directly from the American Lung Association:
> 
> 
> 
> 
> Quote:
> Direct contact with fiberglass materials or exposure to airborne fiberglass dust may irritate the skin, eyes, nose and throat. Fiberglass can cause itching due to mechanical irritation from the fibers. This is not an allergic reaction to the material. Breathing fibers may irritate the airways resulting in coughing and a scratchy throat. Some people are sensitive to the fibers, while others are not. Fiberglass insulation packages display cancer warning labels. These labels are required by the U.S. Occupational Safety and Health Administration (OSHA) based on determinations made by the International Agency for Research on Cancer (IARC) and the National Toxicology Program (NTP).
> 
> 
> 1994- NTP listed fiberglass as "reasonably anticipated to be a human carcinogen" based on animal data.
> 
> 
> 1998- The American Conference of Govern- mental Industrial Hygienists reviewed the available literature and concluded glass wool to be "carcinogenic in experimental animals at a relatively high dose, by route(s) of administra- tion, at site(s), of histologic type(s) or by mechanism(s) that are not considered relevant to worker exposures".
> 
> 
> 1999- OSHA and the manufacturers volunta- rily agreed on ways to control workplace exposures to avoid irritation. As a result, OSHA has stated that it does not intend to regulate exposure to fiberglass insulation. The voluntary agreement, known as the Health & Safety Partnership Program includes a recom- mended exposure level of 1.0 fiber per cubic centimeter (f/cc) based on an 8-hour workday and provides comprehensive work practices.
> 
> 
> 2000- The National Academy of Sciences (NAS) reported that epidemiological studies of glass fiber manufacturing workers indicate "glass fibers do not appear to increase the risk of respiratory system cancer". The NAS supported the exposure limit of 1.0 f/cc that has been the industry recommendation since the early 1990s.
> 
> 
> 2001- The IARC working group revised their previous classification of glass wool being a possible carcinogen. It is currently considered not classifiable as a human carcinogen. Studies done in the past 15 years since the previous report was released, do not provide enough evidence to link this material to any cancer risk.
> 
> Click to expand...
> 
> 
> Here is the link if you wish to check it out yourself:
> 
> http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35439
> 
> 
> In addition i would point out that the American Cancer Society does not even take the time to reference fiberglass.
> 
> 
> The advice given above - protecting both your body and lungs from this product - that makes sense - but the claim that the product is a known carcinogen is not recognized by any government agency of any country that i know.
> 
> 
> The only claims I know that support the cancer myth are made by fringe groups not recognized by any govt or medical agencies that i am aware of. Apparently without any hard scientific backup to support the claims.
> 
> 
> Be safe - be smart - but don't be afraid.........
> 
> 
> Sincerely,
> 
> 
> Rod
Click to expand...


----------



## Dennis Erskine




> Quote:
> but try as I might, I cannot get the center spkr's sound identical to the L & R spkrs.



This can be as a result of any number of issues. First on the diagnostic list is to perform a nearfield RTA of each speaker to determine how much, if any, of the difference is directly related to speaker design, rather than placement (and often you'll find a broken speaker!). Second would be to plot the RTA of the center channel speaker, move the L or R into the same position as the center, measure its RTA and overlay on the original plot. Any differences would be as a result of speaker position.


The fact that one speaker is mounted differently (with respect to the listener) with respect to height, orientation, proximity to boundaries, or angle will change the timbre of the speaker.


Solutions include baffle mounting each speaker to minimize differences or placing all three speakers behind the screen. Regardless of any manufacturer's, or third party party's, claims no screen is 100% acoustically transparent (and, in some cases while measured differences exist, audible differrences do not).


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> This can be as a result of any number of issues. First on the diagnostic list is to perform a nearfield RTA of each speaker to determine how much, if any, of the difference is directly related to speaker design, rather than placement (and often you'll find a broken speaker!).



The speakers are identical. (M&K S-150's and S-150AC)



> Quote:
> Second would be to plot the RTA of the center channel speaker, move the L or R into the same position as the center, measure its RTA and overlay on the original plot. Any differences would be as a result of speaker position.



You're probably onto something here because the left sounds a bit different from the right on the pre/pro's pink noise. However, all spkrs are Omnimounted to the wall and can't easily be swapped around.



> Quote:
> The fact that one speaker is mounted differently (with respect to the listener) with respect to height, orientation, proximity to boundaries, or angle will change the timbre of the speaker.



Another good one, Dennis, and one that never occurred to me. The L&R are level with each other, but while the center spkr is less than one "spkr height" higher than the other two, it is nonethelsss higher. I got lazy when I mounted them and even had to flip it upside down to get it where it is (and use the original mounting location). As part of an upgrade involving bass traps, I plan on lowering all of the speakers and placing them on the same plane.



> Quote:
> Solutions include baffle mounting each speaker to minimize differences or placing all three speakers behind the screen. Regardless of any manufacturer's, or third party party's, claims no screen is 100% acoustically transparent (and, in some cases while measured differences exist, audible differrences do not).



Only the center is behind the screen now and it's not practical to mount L&R behind the screen. Everything sounds fine during use though a hard left to hard right pan can be a bit distracting . . to me . . . but no one else.


With the center speaker being higher, it is firing downward and the sound strikes the screen at an angle. I think that may be contributing to the different timbre and reducing that angle of incidence - or eliminating it - may make my EQ'ing job easier. When "viewed" off axis, a circle is an ellipse (with less area). I'm reasoning that the ellipses are restricting the sound much more than the circles. Does that sound logical?


----------



## Kevin12586

Talk about being lucky. A couple of weeks ago, I went to Joan Fabrics to price out fabric to wrap my panels. I found some acousticallytransparentt fabric for $5.99/yd on sale. They told me based on my panel sizes I would need about 17-20 yards to do what I needed. I decided to wait and shop around a little more.


This week, my wife tells me that Rag Tag had a 'store closing' sign and was trying to get ride of everything, she said that they had fabric, but she was unsure what type I needed. So today we went there and I was able to find some acoustically transparent fabric again, a little difficult with the store being in shambles, and also finding the right color (black). The first fabric I found they only had about 10 yds left, but I noticed they had some more black fabric behind the counter and to my surprise, it was just what I needed. I gave the salesperson the dimensions of my panels and was told I would need about 22 yards. I asked her to check how much was on the roll, and of course it was 1 yard short. So I told her I would take all of it and I also bought 3 yards of the one I originally found.


Oh, by the way, the best part of the story.........the fabric was on sale for *$1.00/yd*










When I reminded my wife how much we almost spent a few weeks ago, she smiled 'almost' as much as I did.


----------



## Irv Kelman




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> 
> Solutions include baffle mounting each speaker to minimize differences.



Dennis, don't you suggest placing the fiberglass on the baffle wall rather than the front of the speaker?.


I can not remember a recommendation to cover the speaker face with fiberglass when I attended THX training.


I would think that would contribute to the difference in sound between treated and non treated speakers.


----------



## pepar




> Quote:
> Originally Posted by *Irv Kelman* /forum/post/0
> 
> 
> Dennis, don't you suggest placing the fiberglass on the baffle wall rather than the front of the speaker?.
> 
> 
> I can not remember a recommendation to cover the speaker face with fiberglass when I attended THX training.
> 
> 
> I would think that would contribute to the difference in sound between treated and non treated speakers.



I occasionally correspond with John Dahl on my home theater project and he is always at the ready to provide assistance. Here is one of his replies re center speaker behind a perfed screen:


"_Jeff,


What you're probably hearing is not so much screen attenuation which can be corrected with EQ, rather you're hearing comb filtering which cannot be corrected with EQ. Two things to do. 1. Make sure that there is at least 6 space between the front face of the speaker and the back of the screen (10 is a bit better). 2. Put a couple of inches of (black color) acoustic absorption material on the front of the speaker with cut outs only for the drivers. This should clean things up considerably. For EQ you want a first order filter hinged at 6KHz. Rolling gradually up from 6KHz to +2dB at 20K.


You've probably done this but be sure you're using broadband (20-20K) pink when you EQ but the internal band limited (500-2K) pink to set the levels. The levels MUST be set accurately before you do a listening test.


Whatever you do pink noise will reveal some differences. To reassure yourself that you've done a good thing play program material through each channel in turn. I doubt you'll be able to hear any differences attributable to the screen and not to room interactions.


Let me know how it works out.


Best regards,


John Dahl

Technical Product Marketing Manager

THX Ltd._


----------



## Westshorestudios

Would 4" - 6" thick rockwool or rigid fiberglass placed underneath my couches provide meaningful bass trapping? I know corners are best, etc., but if that isn't an option for asthetics, how effective would locating these under sofas?


----------



## Ethan Winer

> Would 4" - 6" thick rockwool or rigid fiberglass placed underneath my couches provide meaningful bass trapping?


----------



## pepar




> Quote:
> Originally Posted by *Westshorestudios* /forum/post/0
> 
> 
> Would 4" - 6" thick rockwool or rigid fiberglass placed underneath my couches provide meaningful bass trapping? I know corners are best, etc., but if that isn't an option for asthetics, how effective would locating these under sofas?



For bass traps, especially


----------



## myfipie




> Quote:
> Originally Posted by *Westshorestudios* /forum/post/0
> 
> 
> Would 4" - 6" thick rockwool or rigid fiberglass placed underneath my couches provide meaningful bass trapping? I know corners are best, etc., but if that isn't an option for asthetics, how effective would locating these under sofas?



Have you thought about building a super chunk in the corner? You can put a false wall in front of it and it looks pretty nice.


Glenn


----------



## Weavols

I'm currently setting up new speakers+sub in an ongoing diy home theater project in my living room. After reading through a lot of this thread I think i have a good idea about how to go about treating the room but I have some questions specific to the awkward room design. For one thing, there's a giant un-centered window covering about 40% of the front wall. Does sound generally pass through a window or is it a source of reflection? I mention the window isn't centered because if I push my speakers out as wide as I'd like them one of them is backed by wall while the other is still behind window. I was thinking I could build extentions to the frame of my screen hanging from the ceiling to put absorbtion material behind both speakers. good idea or no?


Also, the house is supported on blocks with wood floors. I'm planning on getting a big throw rug for the front of the room to handle first reflections from the l/c/r but bass seems to stay in the room longer than it should (standing wave?) like my head is inside a speaker cabinet. Are there ways to bass trap via floor modification? I can do some corner and maybe a few wood traps on the wall but if there's a way to stop the floor from shaking so much maybe that would be a good first step? I have plenty of crawlspace and willingness to fight the snakes for it


Thanks in advance!


----------



## pepar




> Quote:
> Originally Posted by *Weavols* /forum/post/0
> 
> 
> I'm currently setting up new speakers+sub in an ongoing diy home theater project in my living room. After reading through a lot of this thread I think i have a good idea about how to go about treating the room but I have some questions specific to the awkward room design. For one thing, there's a giant un-centered window covering about 40% of the front wall. Does sound generally pass through a window or is it a source of reflection?



The window will most likely reflect sound as uniformly as it passes light.



> Quote:
> Also, the house is supported on blocks with wood floors. I'm planning on getting a big throw rug for the front of the room to handle first reflections from the l/c/r but bass seems to stay in the room longer than it should (standing wave?) like my head is inside a speaker cabinet. Are there ways to bass trap via floor modification? I can do some corner and maybe a few wood traps on the wall but if there's a way to stop the floor from shaking so much maybe that would be a good first step? I have plenty of crawlspace and willingness to fight the snakes for it.



The floor *is* trapping when it's shaking. Whatever freequency or frequencies makes it vibate is/are being absorbed. It's the frequencies that are not shaking the floor that are not being trapped and are, most likely, the source of your "head in a speaker cabinet" sensation. Need to know more about your room and it's construction to go further.


----------



## Kevin12586

When I hang my 2'x4' panels vertically on the wall, approximately how far off the ground should they be placed? I know that it depends on the locations of my speakers (I have floorstanders and my center is mounted close to the ceiling pointed down), and of course they have to be mounted so that all FPR from all speakers hit each panel.


I have 2 rows of seats, with the second row on a 12" high riser, and I would prefer to have all my panels mounted level across the room so all/any help would be greatly appreciated.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> When I hang my 2'x4' panels vertically on the wall, approximately how far off the ground should they be placed? I know that it depends on the locations of my speakers (I have floorstanders and my center is mounted close to the ceiling pointed down), and of course they have to be mounted so that all FPR from all speakers hit each panel.
> 
> 
> I have 2 rows of seats, with the second row on a 12" high riser, and I would prefer to have all my panels mounted level across the room so all/any help would be greatly appreciated.



It entirely depends on the locations of the speakers and the audience. If you can do the mirror trick, do it. If not, you need to visualize what the path of each speaker's sound is to each seat. Angle of incidence = angle of reflection. Think bank shots in pool. I know aesthetics are important, but it just shouldn't figure into this equation.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> The window will most likely reflect sound as uniformly as it passes light.



Glass will reflect higher frequencies and pass lower ones. Where that transition is will depend on the thickness of the glass.


Kal


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> Glass will reflect higher frequencies and pass lower ones. Where that transition is will depend on the thickness of the glass.
> 
> 
> Kal



Thanks for "revising and extending" my comment.


----------



## bpape

Kevin,


In general, in most settings, if you mount the panels starting a 2' from the floor and extending to 6' up (assuming 2'x4' panels), you'll cover it. It offers enough vertical coverage for low or high speakers, risers, etc.


Bryan


----------



## Kevin12586

Thanks Bryan, that is the advice I was looking for, now I just need to get my chairs so I can find the actual spots on the wall for my panels


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Thanks Bryan, that is the advice I was looking for, now I just need to get my chairs so I can find the actual spots on the wall for my panels



Ceiling and back wall are first reflection points, too. IN my theater, "doing" the back wall made a huge difference.


----------



## Kevin12586

I have the panels to treat the ceiling, so that is no problem, but I don't have anymore for the rear wall. I am not going to buy a 10 panel bundle, for only a few panels. When I am done, I will have all FRP on one wall treated for all seats (the second wall is over 25' away and decided to leave that alone; no decision either way was made when I asked about it in this thread), bass traps in all corners and 2 ceiling to wall corners, ceiling treated for the front row but not for the 2nd row (I hardly have guests over so if I am going to sacrifice I figured I would do it here).


Maybe in the future I will get more panels and add to the above but considering I had no treatment whatsoever to now having a considerable amount, even though I had to sacrifice in a few places, is good for me.


By the way, last night, just having my FRP panels leaning on the walls, until I get my chairs to put them in their permanent positions, I heard such a great difference that it put a smile on my face. I am far from an audiophile so I won't attempt to describe whether I heard a difference in the mids or highs, but the ability to hear panning from one side of the theater to the next was AMAZING compared to how it was pre-treatment. I clearly heard voices coming from the center of my screen and effects happening in either the left or right speakers. That alone was worth all the effort and money spent, I can't wait until they are up on the walls and I put the FRP on the ceiling.


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> I have the panels to treat the ceiling, so that is no problem, but I don't have anymore for the rear wall. I am not going to buy a 10 panel bundle, for only a few panels. When I am done, I will have all FRP on one wall treated for all seats (the second wall is over 25' away and decided to leave that alone; no decision either way was made when I asked about it in this thread), bass traps in all corners and 2 ceiling to wall corners, ceiling treated for the front row but not for the 2nd row (I hardly have guests over so if I am going to sacrifice I figured I would do it here).
> 
> 
> Maybe in the future I will get more panels and add to the above but considering I had no treatment whatsoever to now having a considerable amount, even though I had to sacrifice in a few places, is good for me.
> 
> 
> By the way, last night, just having my FRP panels leaning on the walls, until I get my chairs to put them in their permanent positions, I heard such a great difference that it put a smile on my face. I am far from an audiophile so I won't attempt to describe whether I heard a difference in the mids or highs, but the ability to hear panning from one side of the theater to the next was AMAZING compared to how it was pre-treatment. I clearly heard voices coming from the center of my screen and effects happening in either the left or right speakers. That alone was worth all the effort and money spent, I can't wait until they are up on the walls and I put the FRP on the ceiling.



Please let us know how big a smile you have when everything's in place! I'm especially interested in hearing your comments on the bass traps.


----------



## Kevin12586

Unfortunately, I won't be getting my chairs for 4-6 weeks (I just ordered them), but I should have the bass traps up in a few weeks and I will let you know.


Have you put up your bass traps yet pepar?


----------



## pepar




> Quote:
> Originally Posted by *Kevin12586* /forum/post/0
> 
> 
> Unfortunately, I won't be getting my chairs for 4-6 weeks (I just ordered them), but I should have the bass traps up in a few weeks and I will let you know.
> 
> 
> Have you put up your bass traps yet pepar?



No, I haven't. I've gotten bogged down in home maintenance/repairs/upgrades and guests who just _have_ to watch a movie. That's part of my interest in your comments after completing your installation.


I did buy an electric knife on ebay, though, and hope to rip the front of my theater apart next week and start stuffing it with 'glass chunks.


----------



## Stima

Well I finally got the room finished and the screen hung all to find out I am very UNDER impressed by the rooms sounds.


Using RoomEQ wizard confirms what my ears are telling me.


Between the two HUGE humps at 100hz and 6khz, there is SERIOUS comb filtering with or without my screen. Turning off the sub(s) does NOTHING to help the bump at 100hz. Running a room mode calculator found at www.RealTraps.com shows there is a mode right at 100hz. I have NO idea why there is such a huge bump at 6khz and a dip at 1khz. The only thing I can think of is my use of all Klipsch speakers. I have KLF-15's for the front, KLF-C7 for a center, and 4x KSP-S6's for surrounds.



So, anyone have any ideas on where to start? I have already tried putting 8, 4"x2'x4' OC705 (also tried left over OC703) panels in the front and back, but they only helped mildly.


I can include screen shots of the full frequency response and\\or waterfall response of the bass end.


----------



## BasementBob

Stima:


Please:

a) start your own thread

b) 3D room dimensions and layout (a drawing or photos would be nice), including doors, windows, speakers, and listener and measurement positions.

c) What's in the room - chairs, carpet, absorbers, diffusers, strange shapes, etc

d) the RoomEQ shots

e) Have you tried single speaker near field measurements to see if there is a defective speaker?

f) What is a KLF-15 ? (I know what a KLF-C7 is)

g) Do you have your receiver's bass management turned on, and is it working (everything lower than 80hz going to a sub). Is it set to 100hz instead of 80hz?

h) Have you tried moving the sub into a null ?

i) Can you describe "UNDER impressed by the rooms sounds" in more detail. What didn't you like? In my case, for example, people are always talking about how great Master And Commander sounds with the cannons -- and they're not impressive at my place.


----------



## Stima

I did start my own thread...no one must of seen it. I mistakenly put it in the game room\\media room area.







I will start one in this area and post back with the info.


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> I did start my own thread...no one must of seen it. I mistakenly put it in the game room\\media room area.
> 
> 
> 
> 
> 
> 
> 
> I will start one in this area and post back with the info.



Maybe just post a link directly to the new thread so that those interested members on this thread can jump directly to it to follow your situation.


----------



## Stima

*EDIT* Corrected link










Direct link to my thread: http://www.avsforum.com/avs-vb/showt...98#post7964198 


Any and all help will be welcomed.


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> Direct link to my thread: http://www.avsforum.com/avs-vb/newre...te=1&p=7964198
> 
> 
> Any and all help will be welcomed.



That link leads to a "post reply" screen to your thread . . .


----------



## Tweakophyte

Hi-


Well... after making my first purchase towards this project 6 months ago







I finally had the time (where the wife and kids were gone) to make my first "superchunk" style, corner, bass trap.


I used

3 - pieces of a JM equivalent to OC703, 2" thick.

1 - FRK panel.

3 - 48"x1" dowels (from HD)

1 - 2'x2' 1/4" hardboard panel (from HD)

6 - screws

about 2 yards of speaker cloth from Joanns Fabrics


You can check out the superchunk info here . I used the 24" pattern on the 3 pieces of fiberglass, and also added the full panel of FRK in front of that. To cut the triangles I used a straight-edge to score the panel with a utility knife, first lightly, then a little deeper. This created an internal channel for the $10 electric carving knife that I used to make the final cut. By the way, this method of scoring then cutting works really well. The internal channel guides the carving knife to the point where you could literally make the cut with little concentration.


The frame is made from the hardboard panes cut a little shorter than in half, diagonally. I used a hand saw because I don't own many power tools. The triangle was estimated using a dry-fit of the 1" dowel, the triangular fiberglass, and the 2" of the FRK.


The bolt of speaker cloth at Joanns was wide enough to use a straight peice of fabric.


No pics (yet) because my wife has the digital camera... sorry.


I'll try to measure the FR at a later date. I want to make a few more panel first.


...just excited to share...


----------



## pepar




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Hi-
> 
> 
> Well... after making my first purchase towards this project 6 months ago
> 
> 
> 
> 
> 
> 
> 
> I finally had the time (where the wife and kids were gone) to make my first "superchunk" style, corner, bass trap.
> 
> 
> I used
> 
> 3 - pieces of a JM equivalent to OC703, 2" thick.
> 
> 1 - FRK panel.
> 
> 3 - 48"x1" dowels (from HD)
> 
> 1 - 2'x2' 1/4" hardboard panel (from HD)
> 
> 6 - screws
> 
> about 2 yards of speaker cloth from Joanns Fabrics
> 
> 
> You can check out the superchunk info here . I used the 24" pattern on the 3 pieces of fiberglass, and also added the full panel of FRK in front of that. To cut the triangles I used a straight-edge to score the panel with a utility knife, first lightly, then a little deeper. This created an internal channel for the $10 electric carving knife that I used to make the final cut. By the way, this method of scoring then cutting works really well. The internal channel guides the carving knife to the point where you could literally make the cut with little concentration.
> 
> 
> The frame is made from the hardboard panes cut a little shorter than in half, diagonally. I used a hand saw because I don't own many power tools. The triangle was estimated using a dry-fit of the 1" dowel, the triangular fiberglass, and the 2" of the FRK.
> 
> 
> The bolt of speaker cloth at Joanns was wide enough to use a straight peice of fabric.
> 
> 
> No pics (yet) because my wife has the digital camera... sorry.
> 
> 
> I'll try to measure the FR at a later date. I want to make a few more panel first.
> 
> 
> ...just excited to share...



And it is appreciated, too! Especially by me, as I have the materials, right down to the ebay-bought electric carving knife, to install SSCs behind my false wall. Pics, FR measurements, whatever you can post, will all be appreciated as well.


Thanks!


----------



## Kevin12586

For those of you that didn't notice this thread in the subwoofer section, here is a thread that I started before I installed any treatments and after I installed some bass traps around my basement. If you go to post 53 of this thread you will see what I did and my frequency response before and after.


Let me know what you think.


----------



## sgx33

Acoustical Treatments question


what is the cheapest way to achive desired acoustics in a home theater?


----------



## Tweakophyte

Okay... here are a few shots from the second trap I made. Since this one was a little smaller than the first, I used 3/4" dowels. There are a few more shots in my gallery.


Empty Frame:










Laying in the wedges:










Getting ready for the final stretch and staple...










Finished product:










The dowel that goes in the corner is peppered with staples... it ain't pretty but it works.


----------



## Tweakophyte

Here are some shots of the beefier panel I made. In this case I put another piece of 2'x4'x2" FRK in front of the wedges and made the top and bottom panels a little larger. It came out very nice, imho. So nice, my wife said it looked good without me asking her opinion!



















...and a view on the top...


----------



## GetGray

It's better to have a filled tringular cavity than a hollow one?


----------



## pepar




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Here are some shots of the beefier panel I made. In this case I put another piece of 2'x4'x2" FRK in front of the wedges and made the top and bottom panels a little larger. It came out very nice, imho. So nice, my wife said it looked good without me asking her opinion!



Very nice indeed, Tweakophyte. Will you be posting any measurements?


----------



## pepar




> Quote:
> Originally Posted by *GetGray* /forum/post/0
> 
> 
> It's better to have a filled tringular cavity than a hollow one?



Hi GetGray, here's a very helpful site for acoustical treatments, including comparisons of different designs. I believe it is where Tweakophyte got his design/ideas.


----------



## Tweakophyte

Hi-


It will be a while before I can have a measurement session. It will only be FR... sorry.


----------



## pepar




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Hi-
> 
> 
> It will be a while before I can have a measurement session. It will only be FR... sorry.



How does it _sound_?


----------



## Tweakophyte

Hi-


I started a break-out thread here because...
I made a short video of me doing my cuts, here. Please note I could not find my mask, so that is part of an old t-shirt







covering my face. Also, since I filmed this myself, my technique is not perfect. Really I just wanted to show how easy this stuff is to work with so you people on the fence can just go do it.


----------



## Tweakophyte




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> How does it _sound_?










I'd love to give you a complete a/b, but that will be a while. I want to do some first-reflection treatment (6 more 2'x4' panels to make) and it will be a while before I can do some critical listening. I also will want to re-calibrate and re-eq the room with the treatments (I'll save the current curve for a potential, future a/b with and without the treatements.)


That said, I did do a little listening. There is a Chemical Brothers track that has a series of long, reverse bass sweeps. These sweeps are very revealing of the FR response of the room. They then go into a deep, musical bass beat which, in the worst of set-ups could sound obviously late (i.e. lots of smear and delay). I did notice it being tighter and smoother, but again, without an a/b session it could all be in my head


----------



## pepar




> Quote:
> Originally Posted by *Tweakophyte* /forum/post/0
> 
> 
> Hi-
> 
> 
> I started a break-out thread here because...
> I made a short video of me doing my cuts, here. Please note I could not find my mask, so that is part of an old t-shirt
> 
> 
> 
> 
> 
> 
> 
> covering my face. Also, since I filmed this myself, my technique is not perfect. Really I just wanted to show how easy this stuff is to work with so you people on the fence can just go do it.



EXCELLENT!! Very informative!


Razor knife and an electric carving knife did make me wonder if it would turn into a self-amputation video . . .


----------



## Sirquack

Just got done using a very sharp fishing knife to cut 12 pieces of OC 703 into 17" x 17" x 24" superchunks. This will be enough to fill the 8ft void from my corners on both sides of the screen, ceiling to stage. I did like the video Tweak







, however I found it easier to cut everything on a board on top of some saw horses.







It was easier on the back....


Tonight I'll be working on the framing to hold the chunks from falling over which will be covered with some nice black felt. Then onto some reflection point treatments.


----------



## Tweakophyte




> Quote:
> Originally Posted by *Sirquack* /forum/post/0
> 
> 
> I did like the video Tweak
> 
> 
> 
> 
> 
> 
> 
> , however I found it easier to cut everything on a board on top of some saw horses.
> 
> 
> 
> 
> 
> 
> 
> It was easier on the back....



See... you missed my point. I wanted to show everyone what you could do with no tools, just a carving knife and an old T-shirt.


----------



## pepar




> Quote:
> Originally Posted by *Sirquack* /forum/post/0
> 
> 
> Just got done using a very sharp fishing knife to cut 12 pieces of OC 703 into 17" x 17" x 24" superchunks. This will be enough to fill the 8ft void from my corners on both sides of the screen, ceiling to stage. I did like the video Tweak
> 
> 
> 
> 
> 
> 
> 
> , however I found it easier to cut everything on a board on top of some saw horses.
> 
> 
> 
> 
> 
> 
> 
> It was easier on the back....
> 
> 
> Tonight I'll be working on the framing to hold the chunks from falling over which will be covered with some nice black felt. Then onto some reflection point treatments.



Make sure you check the acoustical properties of the felt. If it's not acoustically transparent (at mid to higher frequencies) it will be reflective. You may want that, but you should be aware of its effect before applying.


----------



## Sirquack

These are used for rear corner bass traps. I most likely will not use the felt when I work on my reflection treatments. BPape and Ethan did not see a problem with using this felt for corner bass traps. Besides, you can see light through the material, and it also passes the breath test. Low frequencies should not be an issue.


----------



## pepar




> Quote:
> Originally Posted by *Sirquack* /forum/post/0
> 
> 
> These are used for rear corner bass traps. I most likely will not use the felt when I work on my reflection treatments. BPape and Ethan did not see a problem with using this felt for corner bass traps. Besides, you can see light through the material, and it also passes the breath test. Low frequencies should not be an issue.



Sounds like you've already researched and addressed that issue then.


----------



## Trevdor

Ok, here's a couple of dumb questions for you all... Does a Insul-Shield type product have a surface that can be painted after it is installed? And rather than putting filler above it to even out the wall could I just place some moulding above it to separte it visually from the area above? The moulding might look like it is a little high on the wall but it seems like it would be easier than the other methods I've seen mentioned...


----------



## bpape

No - don't paint it - you'll mess up the absorbtive properties.


As far as not doing the wall tops and just covering the bottom - sure, you can do that.


Bryan


----------



## Trevdor

So then do the Insul-Shield type products come in different colors? I've also seen fabric panels, do those do basically the same thing as the Insul-Shield?


----------



## Dennis Erskine

Insul-shield is not a room finish...it is a room treatment. Insul-shield is either installed behind fabric or wrapped in fabric.


----------



## BasementBob

GoM Fabric colour charts (pictures of the fabric's weave)
http://www.silentsource.com/gom_index.html 
http://www.getridofnoise.com/FabritecColorChart.html


----------



## titch--

Hello guys










I got a question for the pros here. I made 1 of 8 little bass traps thats going up across the ceiling/front wall. They are 1 ft chunks that are 5 1/2'' thick. Im just wondering if Im wasting my time by making these?











thx


----------



## pepar




> Quote:
> Originally Posted by *titch--* /forum/post/0
> 
> 
> Hello guys
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I got a question for the pros here. I made 1 of 8 little bass traps thats going up across the ceiling/front wall. They are 1 ft chunks that are 5 1/2'' thick. Im just wondering if Im wasting my time by making these?
> 
> 
> thx



this size will not have any effect at the low end - maybe not even into subwoofer frequencies.


----------



## bpape

Well, if you make enough of them, you'll get enough square footage to make some difference. The problem is that each one isn't that much surface area and they're not terribly thick.


Hey, they're better than nothing for sure - depending on what's inside and how they're constructed.


Bryan


----------



## Sirquack

I just finished my 8ft high 17" x 17" x 24" superchunk bass traps for the rear corners next to my HT Screen. I used OC 703 and built some frames out of 1" x 2" pine that I covered with black felt. Thanks to Bryan P. for all his advice.





























Below is a before/after graph, what do you all think. I think overall, there is some good improvement. I do notice a difference when I listen to music now, only with these 2 traps.



















I plan to do some more bass traps asap, and then maybe look at some first reflection treatments. The room is about 30ft x 31ft overall, however, the HT portion is set back in one corner about 6ft, so really it is kinda L shaped. The back wall where the screen resides is 15ft wide and sits back 6ft to make it more private. After that 6ft, it opens up into the larger room. I also have 9ft ceilings.


----------



## pepar




> Quote:
> Originally Posted by *Sirquack* /forum/post/0
> 
> 
> I just finished my 8ft high 17" x 17" x 24" superchunk bass traps for the rear corners next to my HT Screen. I used OC 703 and built some frames out of 1" x 2" pine that I covered with black felt. Thanks to Bryan P. for all his advice.
> 
> Below is a before/after graph, what do you all think. I think overall, there is some good improvement. I do notice a difference when I listen to music now, only with these 2 traps.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I plan to do some more bass traps asap, and then maybe look at some first reflection treatments. The room is about 30ft x 31ft overall, however, the HT portion is set back in one corner about 6ft, so really it is kinda L shaped. The back wall where the screen resides is 15ft wide and sits back 6ft to make it more private. After that 6ft, it opens up into the larger room. I also have 9ft ceilings.



That's GREAT that your 24" face SSCs are absorbing below 80Hz, and especially below 50Hz. My plan is to build the 24" face version, but I was concerned that it would be necessary to build 'em with the full 34" face in the Studiotips design to get to the lower frequencies.


And excellent job aesthetically as well! Thanks for the post!


----------



## titch--

I guess I should of said that I already have 2 bass traps in my front corners, from floor to ceiling. I just wanted maximum coverage of the corners of my room. So I thought I would try and put something up by the ceiling/front wall as well.


These traps are made of some very dence/heavy fiberglass that I found, never seen anything like it before.


thx


----------



## BasementBob

Sirquack:


By any chance are your FL and FR speakers about 2' from the side wall and about 14" from the front wall (measured from center of tweater)?


Where in the room was that measurement taken?


----------



## Scott R. Foster

SQ:


You Rock!


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Sirquack:
> 
> 
> By any chance are your FL and FR speakers about 2' from the side wall and about 14" from the front wall (measured from center of tweater)?
> 
> 
> Where in the room was that measurement taken?



Beside the pictures showing that to be - roughly - the case, I get the impression that something in the FR charts told you this. Right?


----------



## Sirquack

Thanks Scott










Hi Bob! Off the top of my head the mains are about 22-23" from the front wall (the Axioms are 15" deep) and are about 26" from the side walls. I also have them toed in a bit, maybe to far? I saw on Ethan Winers website he has a picture where all the speakers point right at the prime listening position. I've never toed my mains in this much. Even if my Axioms are facing straight forward, the soundstage is great.


In both situations the SPL meter was placed on a tripod in my center recliner, exactly where my ears would be. This is also exactly 38% back from the front wall.


This is an old picture that does not include the above bass traps, in addition, the center channel is now mounted up further on the wall right below the screen.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> That's GREAT that your 24" face SSCs are absorbing below 80Hz, and especially below 50Hz. My plan is to build the 24" face version, but I was concerned that it would be necessary to build 'em with the full 34" face in the Studiotips design to get to the lower frequencies.
> 
> 
> And excellent job aesthetically as well! Thanks for the post!



If you can fit a 34" one in your room then go for it. We built a prototype and found it to be HUGE! But if you have the space then go for it.


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> If you can fit a 34" one in your room then go for it. We built a prototype and found it to be HUGE! But if you have the space then go for it.
> 
> 
> Glenn



Even behind my false wall the 34" faced SSC would be a problem as it would encroach upon speaker mounts and even the false wall itself. If I ever build another house though . . .


----------



## TumaraBaap




> Quote:
> Originally Posted by *GetGray* /forum/post/0
> 
> 
> It's better to have a filled tringular cavity than a hollow one?



A hollow one is definitely not as effective as a filled one. My concern is that if you're filling the entire cavity, the density of the fiberglass is less critical, and using a solid 703 superchunk style trap appears wasteful. A less dense product for starters is more "inviting" to moving air particles. It will reflect less sound. Energy conversion to heat through friction won't be as efficient as 703 or 705, but if you have enough fiberglass depth it will eventually happen deeper in the bowels of interstitial spaces. So if you place a 1 inch or 2 inch 703 FSK panel (with 45 degree miter cut sides) against a corner, floor to ceiling, and just stuff the cavity behind with fluffy R-38 insulation, you'd have an equally well performing bass trap. And it will cost a fraction of a solid 703 superchunk trap.

Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> . . . So if you place a 1 inch or 2 inch 703 FSK panel (with 45 degree miter cut sides) against a corner, floor to ceiling, and just stuff the cavity behind with fluffy R-38 insulation, you'd have an equally well performing bass trap. And it will cost a fraction of a solid 703 superchunk trap.
> 
> Tumara Baap



You're right about the cost, but I'd want to see data on the "equally well performing" part vis-a-vis 703.


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> You're right about the cost, but I'd want to see data on the "equally well performing" part vis-a-vis 703.



Sorry, I was too casual in my choice of words. I meant something along the lines of "respectable performance" or "acceptable performance", or "for all practical purposes, very effective performance." As a matter of fact if one could shift some of the cost advantage to treating a greater surface area, any superchunk 703 superiority would be further negated, and maybe even trumped.

I don't know how the hard numbers would pan out of one versus the other. However, Ethan Winer has done tests juggling a number of variables, such as fiberglass density, surface area, and panel depth. The take home point was that beyond a certain depth of 8 inches or so, density of fiberglass makes a piddling difference to performance.


Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> Sorry, I was too casual in my choice of words. I meant something along the lines of "respectable performance" or "acceptable performance", or "for all practical purposes, very effective performance." As a matter of fact if one could shift some of the cost advantage to treating a greater surface area, any superchunk 703 superiority would be further negated, and maybe even trumped.
> 
> I don't know how the hard numbers would pan out of one versus the other. However, Ethan Winer has done tests juggling a number of variables, such as fiberglass density, surface area, and panel depth. The take home point was that beyond a certain depth of 8 inches or so, density of fiberglass makes a piddling difference to performance.
> 
> 
> Tumara Baap



If I hear you correctly - if finances make the choice between doing it as you suggest and not doing it at all, definitely choose the former. A large majority have nothing, so it would be a great improvement.


----------



## Sirquack

I thought I would update the above drawing to give you all a better idea of what the room looks like. Keep in mind this is not to scale.










Since I have completed my Superchunk Traps on the front wall, my next plans are to build some column traps to go in the rear corners.


I would also like to put some bass traps where the walls/ceiling meet in the HT area above where I'm thinking about putting some 1st reflection treatments. Also, I eventually might put some 1st reflection on the ceiling locations.


As you can see, there is a 10" bulk head dropped along the entire width of the room, I might be able to put some smaller bass traps up in the corner facing the screen?


What do you all think?











Also, I have a few questions for using 703 for 1st Reflection Treatments:


1) First of all, am I correct in saying I want to leave some space behind the 703 and the wall, within the frame I build?


2) Also, do I want to use the FRK(scrim) on the side facing the room, or use regular 703 with no facing?


3) For those wall/ceiling treatments do most people use 2" thick or double up and use 4" thick 703?


Thanks in advance, Randy


----------



## Terry Montlick




> Quote:
> Originally Posted by *Sirquack* /forum/post/0
> 
> 
> ...
> 
> Also, I have a few questions for using 703 for 1st Reflection Treatments:
> 
> 
> 1) First of all, am I correct in saying I want to leave some space behind the 703 and the wall, within the frame I build?
> 
> 
> 2) Also, do I want to use the FRK(scrim) on the side facing the room, or use regular 703 with no facing?
> 
> 
> 3) For those wall/ceiling treatments do most people use 2" thick or double up and use 4" thick 703?
> 
> 
> Thanks in advance, Randy



For the treatment of first reflections:


1. There is no need to leave any space.

2. Don't face the FRK side towards the room.

3. A 2" thickness is enough.


- Terry


----------



## myfipie

As Terry said you don't have to leave a space, but if you do it will pick up not only a little more low end (which all rooms need) but will also pick up more high end due to sound coming in from the sides also. If you do space it you don't want to have any facing on the back of the panel.


Glenn


----------



## Sirquack

Thanks guys,


Glenn, one question. When looking at the pictures of your 244's on the Audioholics review, it appears your spacing is built into the framing, however, I don't see any holes that would allow sound to come in from the sides? Are you saying the high end is traveling through the wood framing? Now when I look at the RealTraps design, it appears they have a slotted hole design around the perimeter of the frame, which appears to be aluminum?


Thanks, Randy


----------



## KERMIE




> Quote:
> Originally Posted by *Sirquack* /forum/post/0



Looking at this, is it important to have a bass trap in the bottom right hand corner (by your fridge) even thourgh it is 31 feet away.


Just looking for some expert advice. I have a similar set up....


thanks


----------



## Sirquack

Hey Kermie, BPape on this forum had told me once this might be a good idea. I'm still looking for suggestions as this is a very large room. I've noticed with my Axiom EP500 Sub, that this opposite corner seems to have a lot of low bass.


----------



## myfipie




> Quote:
> Originally Posted by *Sirquack* /forum/post/0
> 
> 
> Thanks guys,
> 
> 
> Glenn, one question. When looking at the pictures of your 244's on the Audioholics review, it appears your spacing is built into the framing, however, I don't see any holes that would allow sound to come in from the sides? Are you saying the high end is traveling through the wood framing? Now when I look at the RealTraps design, it appears they have a slotted hole design around the perimeter of the frame, which appears to be aluminum?
> 
> 
> Thanks, Randy



Our frame is built to the back so the sides are open for sound to come in. Even though the panel does have a natural spacer to it I still recommend spacing it off the wall to let sound come in from the back. It will also increase the low end absorption.


Glenn


----------



## Tweakophyte




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> A hollow one is definitely not as effective as a filled one. My concern is that if you're filling the entire cavity, the density of the fiberglass is less critical, and using a solid 703 superchunk style trap appears wasteful. A less dense product for starters is more "inviting" to moving air particles. It will reflect less sound. Energy conversion to heat through friction won't be as efficient as 703 or 705, but if you have enough fiberglass depth it will eventually happen deeper in the bowels of interstitial spaces. So if you place a 1 inch or 2 inch 703 FSK panel (with 45 degree miter cut sides) against a corner, floor to ceiling, and just stuff the cavity behind with fluffy R-38 insulation, you'd have an equally well performing bass trap. And it will cost a fraction of a solid 703 superchunk trap.
> 
> Tumara Baap



Itchy!


Btw, it only took 3 panels to make the basic superchunk, and 4 when I added a piece of FRK to the larger one. It does take more time to cut, but I am not sure how much you'll save versus the PIA factor of using the fluffy stuff. I thought you were supposed to pack the fluffy stuff when you used it for trapping, like the way it is in the package. The panels cost me $9 (round numbers), so $18 for two. Just curious... How much would the fluffy stuff cost to fill the cavity?


I am itchy just thinking about it!


----------



## Tweakophyte

I used some chair glides and thich felt to give my panels some space away from the wall. I found that I liked having the space away from the front wall for deeper absorbtion, but the side walls looked better with thinner panels... until my wife saw them...











Here are some more shots...


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Our frame is built to the back so the sides are open for sound to come in. Even though the panel does have a natural spacer to it I still recommend spacing it off the wall to let sound come in from the back. It will also increase the low end absorption.



Hi Glenn, can you point me to some data on that spacing? Every SSC installation I've seen has them tight in the corner.


----------



## myfipie

If you goto our website it has the 244 as A mount, Recommended wall mount and recommended corner mount. The Recommended wall mount is spaced off the wall. If you can not find it drop me a email and I can send it to you. AVS really does not want companies putting links to there websites.


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> If you goto our website it has the 244 as A mount, Recommended wall mount and recommended corner mount. The Recommended wall mount is spaced off the wall. If you can not find it drop me a email and I can send it to you. AVS really does not want companies putting links to there websites.
> 
> 
> Glenn



Oh, OK, I'm familiar with standing panels off the wall. I evidently misunderstood (or didn't read) you to be saying the "chunk" bass trap should be spaced out - no pun intended from the corner.


----------



## McCall

Can anyone tell me how Auralex Sheetblock sound barrier would be used? Would it be placed like the linacoustic or other such things to absorb, or deaden a wall? or is it for some other purpose? How would something like that over Homosote work?


I know these are insanely simpleminded questions, but I know NOTHING about acoustics and after reading here and other sites for two weeks I still Know NOTHING about acoustics. I am a 54 year old mother of five and this stuff is not going to come easy for me.


I have a room that was my bedroom that already has a "stage" area and the makings of a home theather it is down a downsloping hallway 30 ft from my main house on a concrete slab. I will be retrofiting it not redoing from scratch.


My stage is 140" wide and my speakers in front will all be behind an SMX screen of yet undertermined size. currently there is a 30" deep bookcase area along this entire wall and I would like to use that as the area to mount the various speakers behind the screen but I see I need to either put backing behind them or encase them more or something.


It will be a 7.1 speaker system with a B&W cm center speaker, front speakers are KEF 102's , rears are KEF Q3's and surrounds are KEF TDM 34 DS Sub is Velodyne 12" forget model number.


the room is about 170" wide by 18' long I say about because it has some closets and other small side areas off the main part of the room.

I am going to have three rows of Stadium style seating.


I am finding many of these sound treatment items very hard to find, I can get Auralex items online but not many of the other things.


Any suggestions? and please remember I am a lady at least try to be nice! LOL


----------



## KERMIE

I am building some acoustical frames and some are 1.5 inches deep.


I have 1" Linacoustic to use for this.


My question is how tight should I have the Linacoustic up against the GOM Fabric. I tried to just snug fit it in there but it still falls too deep and I have about 1/4" gap between the GOM and the Linacoustic.


Options


1. build out the depth to 1"


2. add 1/4" or 1/2" of batting (the linacoustic is attached to the wall already.) ....


thank you for you help..



One more thing...


Would using plastic door screen material over the frame hurt. You can get it in rolls at HD. It would keep everything in and the GOM tight on top.


----------



## dcollin4444

I'm soundproofing my ceiling in my basement, R-19 in-between joists & I'm trying to figure out what's the best way to go for the buck.

Would people suggest:

A. RSIC-1 Sound Isolation Clip snapped into a 7/8" drywall furring channel attached to 1/2" drywall

or

B. IsoMax Resilient Sound Isolation Clip snapped into a 7/8" drywall furring channel attached to 1/2" drywall?


Both seem to run about the same amount of money, but if I go with a RC-1, the price goes down quite a bit. I'm on a budget, but I don't want to do to little & regret it later, but if most think the RC-1 would keep most of the lows downstairs, it'd save me $ in the long run, but if not, would you recommend RSIC-1 or IsoMax clips?

Thanks!


----------



## myfipie

"Would using plastic door screen material over the frame hurt. You can get it in rolls at HD. It would keep everything in and the GOM tight on top. "


Speak into it and if you can not hear it reflecting back at you then you might just be ok. I have never tried it but I could see how it could work.


Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> "Would using plastic door screen material over the frame hurt. You can get it in rolls at HD. It would keep everything in and the GOM tight on top. "
> 
> 
> Speak into it and if you can not hear it reflecting back at you then you might just be ok. I have never tried it but I could see how it could work.
> 
> 
> Glenn



I think he means (simply) plastic "screen." So, yes, you can talk through it.


----------



## KERMIE




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I think he means (simply) plastic "screen." So, yes, you can talk through it.




That is funny...yep it is a "Screen". Something like this..


----------



## jvgatto

I am in the process of finishing a 16 wide by 22 deep dedicated theater, and would like to add ~8 acoustic panels plus bass traps in 3 corners. The theater is located on the 3rd floor, with bedrooms below. The walls are 1/2 in sheetrock and the floor is 3/4 with carpet and no special padding. Ceiling height is 8 feet; walls are 6 feet with a 45 degree pitch from 6 feet to 8 feet.


Sound transmission to the floors below is surprising low, so my main objective is to reduce room reflections and control bass.


I can get Roxul RHT 80 mineral wool (2", 8 pcf) for 60 cents a sq ft, or the 703 OC 2" FRK for $1.07. The acoustic properties for the RHT 80 listed on Bob Gold's site are comparable, but I have seen concerns in various threads about 8 pcf being too dense. I have not seen a conclusive explanation on the difference. At approximately 150 sq ft, we are only talking $60, but would like to understand if there is enough of a difference. (The RHT supplier is closer, easier to get)


Thanks


----------



## CriticalListener

I've always liked referencing Bob Gold's Coefficient chart http://www.bobgolds.com/AbsorptionCoefficients.htm , but I noticed he stopped the chart after Owens Corning 1280. While 1280 had an absorption coefficient (a.c.) of 1.11, which is bested by 703 (1.19), I couldn't help but notice this information available from Owens Corning ( http://sti.fmpdata.net/ftp/datasheet/PDS-SSAMW.pdf ), that type 1212 has a 12lb/ft density, where as 1280 has an 8lb/ft density. Looking at Bob's chart, one could assume that density is the big factor in why 4" thick 1280 has an a.c. of 1.11 @ 125 hz, while 4" thick 1240 only has 0.88 a.c. @ 125 hz.


My thinking is that if 1280's 100% greater density than 1240 amounts to an additional a.c. of .23, 1212's 50% greater density than 1280 could add at least another .11, pushing 1212 to an a.c. of 1.23 @ 125hz.


I know I'm coming late to this party, but if someone has information on 1212, I'd greatly appreciate learning about it. As Dennis Erskine can attest, fiberglass bass absorption is not part of the HAA curriculum.


----------



## Ethan Winer

> 1280 had an absorption coefficient (a.c.) of 1.11, which is bested by 703 (1.19)


----------



## CriticalListener




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> > fiberglass bass absorption is not part of the HAA curriculum.


----------



## pepar




> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> No, I'm not saying that. But in the three days of training, so much was packed in that bass trapping (and Helmholtz resonators) were only spoken about for about an hour. There wasn't the kind of time to go into building bass traps for clients, what materials to make them out of, etc.



What was the bulk of the course focused on?


----------



## CriticalListener




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> What was the bulk of the course focused on?



We focused on the length of sound waves and their interaction with walls, reflective surfaces, goals of good sound (focus, response, dynamics), speaker placement, when sound waves become omnidirectional, math equations, using acoustic test equipment and test tones - the list goes on and on. We discussed bass trapping, but not building one.


Now back to my original question - anyone use and/or test the Owens Corning 1212 material?


----------



## myfipie




> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> No, I'm not saying that. But in the three days of training, so much was packed in that bass trapping (and Helmholtz resonators) were only spoken about for about an hour. There wasn't the kind of time to go into building bass traps for clients, what materials to make them out of, etc.



Isn't that like learning how to build a car but not telling you how to put the wheels on?

















Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Isn't that like learning how to build a car but not telling you how to put the wheels on?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Glenn



It's only a tree-day course; they can't go into depth on everything. And, IMO, a more apt analogy is that it's like learning how to build a car, but not telling you how to spin balance the wheels. The car will still run, but it's not "optimized."


----------



## CriticalListener




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> It's only a tree-day course; they can't go into depth on everything. And, IMO, a more apt analogy is that it's like learning how to build a car, but not telling you how to spin balance the wheels. The car will still run, but it's not "optimized."



I think I have been unclear in explaining the HAA course. We are not told how to BUILD bass traps, we are told to buy them. I'm trying to figure out how to build them.


So a better analogy would be we are being told how to fine-tune a car, but aren't told how to make our own spark plugs.


----------



## Ethan Winer

> We are not told how to BUILD bass traps, we are told to buy them.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> A couple of minor points: diffusors do not affect RT60 in the manner described nor will they have any impact on standing waves.



Hi Dennis,


I have observed, and the literature strongly suggests, that RT60 is lowered with added diffusion, at least when the absorptions of different room surfaces vary.


See:

M. R. Hodgson, Evidence of diffuse surface reflections in rooms, J. Acoust. Soc. Am. 89, 765-771 (1991).

M. Lam, A comparison of three diffuse reflection modeling methods used in room acoustics computer models, J. Acoust. Soc. Am. 100, 2181-2191 (1996).

M. Lam, The dependence of diffusion parameters in a room acoustics prediction model on auditorium sizes and shapes," J. Acoust. Soc. Am. 100, 2193-2203 (1996).

M. Hodgson and E. Nosal, "Experimental evaluation of radiosity for room sound-field prediction," J. Acoust. Soc. Am. 120, 808-819 (2006).


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> I have observed, and the literature strongly suggests, that RT60 is lowered with added diffusion, at least when the absorptions of different room surfaces vary.



Hi, Terry, will you please expand on that, especially your qualification with different room surface absorptions? And, if possible, perhaps couch it in layman's terms?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Hi, Terry, will you please expand on that, especially your qualification with different room surface absorptions? And, if possible, perhaps couch it in layman's terms?



Sure!


The notion is that when you have a range of different absorption coefficients on surfaces in a room, the surfaces with less absorption have greater influence on the reverberation time. These "more-live" surfaces make the reverberation time longer -- longer, in fact, than would be predicted by a reverberation time formula such as the Eyring equation. [With a mix of absorption coefficients, some of them being large, the Eyring reverberation time formula should be used instead of the Sabine formula.]


But when you add diffusion, you mix up the wave directions a lot. This causes waves that might otherwise get stuck reflecting only between less absorptive surfaces to hit and be absorbed by surfaces with higher absorption coefficients. The reverberation dies out quicker. The results conform much better with the Eyring equation, which in fact presumes a diffuse sound field. And that's just what diffusion provides.


- Terry


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> It's only a tree-day course; they can't go into depth on everything. And, IMO, a more apt analogy is that it's like learning how to build a car, but not telling you how to spin balance the wheels. The car will still run, but it's not "optimized."



So would you like to go back and forth and insult each other about this for about 4 pages?






































Glenn


----------



## myfipie




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> > We are not told how to BUILD bass traps, we are told to buy them.


----------



## CriticalListener

It seems that, in my area, 705 & 1212 are nearly impossible to find. So I took Ethan's suggestion on his website and found a Knauff FSK board that is 6lbs/foot and ordered that (not a great price $1.71 sq ft) but with nothing else available I took it.


Normally I would buy the bass traps, but I'm having my carpenter build 7' x 2' frames of stained wood that match the other carpentry work in my showroom. I'm going to cover them with my left over 1" Owens Corning Black Acoustic board, and I hope they will come out looking very sharp.


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> So would you like to go back and forth and insult each other about this for about 4 pages?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Glenn



I have a strict one-page limit on that.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Sure!
> 
> 
> The notion is that when you have a range of different absorption coefficients on surfaces in a room, the surfaces with less absorption have greater influence on the reverberation time. These "more-live" surfaces make the reverberation time longer -- longer, in fact, than would be predicted by a reverberation time formula such as the Eyring equation. [With a mix of absorption coefficients, some of them being large, the Eyring reverberation time formula should be used instead of the Sabine formula.]
> 
> 
> But when you add diffusion, you mix up the wave directions a lot. This causes waves that might otherwise get stuck reflecting only between less absorptive surfaces to hit and be absorbed by surfaces with higher absorption coefficients. The reverberation dies out quicker. The results conform much better with the Eyring equation, which in fact presumes a diffuse sound field. And that's just what diffusion provides.
> 
> 
> - Terry



Thanks, I see and understand the premise. Is this always the case? Isn't it just as likely that sound that would have been reflected onto an absorptive surface instead is reflected onto a reflective surface?


----------



## pepar




> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> It seems that, in my area, 705 & 1212 are nearly impossible to find. So I took Ethan's suggestion on his website and found a Knauff FSK board that is 6lbs/foot and ordered that (not a great price $1.71 sq ft) but with nothing else available I took it.
> 
> 
> Normally I would buy the bass traps, but I'm having my carpenter build 7' x 2' frames of stained wood that match the other carpentry work in my showroom. I'm going to cover them with my left over 1" Owens Corning Black Acoustic board, and I hope they will come out looking very sharp.



I ordered my 703 from an HVAC insulation distributor. (I could have just as easily ordered 705.) Got my J-M Linacoustic and OC SelectSound Black from them as well. Killer pricing, but I had to pick it up. Got the roll of Linacoustic into the SUV, but had to rent a truck to pick up the 4x8x2 sheets of SelectSound.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Thanks, I see and understand the premise. Is this always the case? Isn't it just as likely that sound that would have been reflected onto an absorptive surface instead is reflected onto a reflective surface?



Yes, but that reflected sound will soon have more chances to hit the absorptive surfaces. The randomness added by the diffusion provides this.


"Always" is a word I am hesitant to use. In the papers I referred to earlier, the lowering of RT60 with increased absorption was consistently shown. The rooms ranged from simple boxes to complex concert halls. This doesn't mean that one could not come up with an artificial example room which exhibited the reverse.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> In the papers I referred to earlier, the lowering of RT60 with increased absorption was consistently shown. The rooms ranged from simple boxes to complex concert halls. This doesn't mean that one could not come up with an artificial example room which exhibited the reverse.



You mean "diffusion" there, right?


I'm thinking of adding diffusors - Skyline LPs - to my theater to make it a bit livelier. I will run some RT60 tests first to be sure it's needed, but my ears and experience (live sound and a bit of studio work) lead me to think that I do. Some of the Skylines would be mounted onto parts of my false wall, behind which is 2" Linacoustic, and soon some superchunks. As this will, for above-bass frequencies, be "replacing" absorption with diffusion, is it likely that this *will* increase my RT60?


Other spots I've eyed are directly fired at by my side dipoles and are now plaster. My thinking was that this would contribute to a greater sense of envelopment by the surround fields. Am I on the wrong track?


Thanks again.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> You mean "diffusion" there, right?
> 
> 
> I'm thinking of adding diffusors - Skyline LPs - to my theater to make it a bit livelier. I will run some RT60 tests first to be sure it's needed, but my ears and experience (live sound and a bit of studio work) lead me to think that I do. Some of the Skylines would be mounted onto parts of my false wall, behind which is 2" Linacoustic, and soon some superchunks. As this will, for above-bass frequencies, be "replacing" absorption with diffusion, is it likely that this *will* increase my RT60?
> 
> 
> Other spots I've eyed are directly fired at by my side dipoles and are now plaster. My thinking was that this would contribute to a greater sense of envelopment by the surround fields. Am I on the wrong track?
> 
> 
> Thanks again.



Yes, I meant "diffusion."










If you are mounting Skylines over what is now 2" thick Linacoustic, I wouldn't worry at all about driving down the reverberation time. You are effectively reducing the existing absorption by covering up some highly absorptive material. The studies I cited kept the absorption the same while changing the diffusion coefficients only. And a few small diffusers on the walls shouldn't measurably affect RT60, while they may signficantly enhance the sense of spaciousness.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> . . The studies I cited kept the absorption the same while changing the diffusion coefficients only. And a few small diffusers on the walls shouldn't measurably affect RT60, while they may signficantly enhance the sense of spaciousness.



That seems to be a THX-driven issue - envelopment. And personally, I like that feeling. But I rarely read anything on that. Home theater acoustics seem to be limited to RT60 and frequency response. CriticalListener mentioned his HAA Level 1 course touched on "sound waves become omnidirectional", but I'm not sure that could be contrued as envelopment. Your comment on spaciousness is one of the few on that topic that I've read from an acoustician. Am I just missing that discourse?


----------



## CriticalListener




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> That seems to be a THX-driven issue - envelopment. And personally, I like that feeling. But I rarely read anything on that. Home theater acoustics seem to be limited to RT60 and frequency response. CriticalListener mentioned his HAA Level 1 course touched on "sound waves become omnidirectional", but I'm not sure that could be contrued as envelopment. Your comment on spaciousness is one of the few on that topic that I've read from an acoustician. Am I just missing that discourse?



The point about omnidirectional was a topic at HAA training and is based on when listeners can no longer pinpoint where sound is coming from. For most people this occurs below 125 hz. Thus a sub placed in any part of a room, with the crossover set to 125 hz or lower, should be impossible for a blindfolded person to point to. This has nothing to do with envelopment.


However we all discussed in detail the important aspects of sound quality, which I remember by using the acronym FRED C. [Focus, Response, Envelopment, Dynamics, Clarity].


----------



## pepar




> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> 
> However we all discussed in detail the important aspects of sound quality, which I remember by using the acronym FRED C. [Focus, Response, Envelopment, Dynamics, Clarity].



Ahh yes, there it is; envelopment.


----------



## bpape

Having the ONLY sub in the room behind me is, to me, very distracting - even with an 80Hz xover. May just be me.


Also, especially with a 125Hz or 100Hz xover, it would have to be a very good sub with zero port noise, little to no distortion, etc - as those things are absolutely very localizable and can't be filtered with the xover.


Lastly, you have to have the flexibility to delay the sub enough to appropriately align with the mains - many receivers don't have enough play on the sub to do this. And, you can't do it with the phase control as some will try to do as that is frequency dependent.


Just a thought.


Bryan


----------



## Kal Rubinson




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Having the ONLY sub in the room behind me is, to me, very distracting - even with an 80Hz xover. May just be me.



As you indicate, it is implementation-dependant. However, for most applications, I use it for LFE and bass-manage only the rear channels. Thus, with a 70Hz crossover, sealed enclosure, servo-control and adequate delay (and phase and EQ) control, it works just fine for me.










Kal


----------



## bpape

Absolutely Kal. Every application is different.


Bryan


----------



## nowandthen

Whew! I just finshed reading through this entire thread.


One area that has not been discussed: Using a riser for a base trap. I have seen this mentioned but have not seen any discussion in this thread. Assuming I have a 12" riser that is roughly 12' x 9', can this be used for a base trap? If so how would that be done? Also, I do plan to add buttkickers to the risers if that matters.


Thanks,


Todd


----------



## Ethan Winer

Terry,


> I have observed, and the literature strongly suggests, that RT60 is lowered with added diffusion


----------



## pepar




> Quote:
> Originally Posted by *nowandthen* /forum/post/0
> 
> 
> Whew! I just finshed reading through this entire thread.
> 
> 
> One area that has not been discussed: Using a riser for a base trap. I have seen this mentioned but have not seen any discussion in this thread. Assuming I have a 12" riser that is roughly 12' x 9', can this be used for a base trap? If so how would that be done? Also, I do plan to add buttkickers to the risers if that matters.
> 
> 
> Thanks,
> 
> 
> Todd



If your riser is buttkicker driven, it may not be very effective as a bass trap.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry,
> 
> 
> > I have observed, and the literature strongly suggests, that RT60 is lowered with added diffusion


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Yes, the added absorption for QRD-type diffusers which RPG publishes is over and above the diffusion-absorption effect I described.
> 
> 
> - Terry



Are they absorbing frequencies that they are not diffusing? Are they absorbing any _significant_ amount of the frequencies that they are diffusing?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Are they absorbing frequencies that they are not diffusing? Are they absorbing any _significant_ amount of the frequencies that they are diffusing?



The QRD-specific absorption (which is measured in a diffuse sound field, via the standard reverberation room method) is significant. It was first noticed in concert halls in the early days of QRD installation. The RT60 became unusually low, and diffusers needed to be removed.


Since then, the theory for this extra absorption has been worked out by a researcher in Japan -- I forgot who. He also found that some kind of surface coating can reduce this absorption. My simplistic understanding of the theory is that the sharp changes in phase at adjacent QRD wells also causes pressure change, and this induces lateral air movement (much like adjacent high and low pressure weather systems) which removes energy via friction.


- Terry


----------



## BasementBob

Terry Montlick:


I believe QRD's are also quarter wavelength resonator absorbers [I probably phrased that a bit off].

And the absorption increases if you put a membrane (even acoustically transparent cloth) in front of a diffuser, according to RPG (recall that marketing page).


----------



## mschiff

Hi Ethan,


I downloaded your Real Traps Test Tone CD yesterday, and did a quick check of my home theater space. I set the level to 70db using the pink noise, and then just did a quick check at the beginning of each track. I had nothing below 60db, and nothing significantly above 80db. From 100 Hz up, I don't think it varied more then 5db either side of 70. Does this mean I'm in pretty good shape, or do I really need to check each tone?


-- Martin


----------



## pepar




> Quote:
> Originally Posted by *mschiff* /forum/post/0
> 
> 
> Hi Ethan,
> 
> 
> I downloaded your Real Traps Test Tone CD yesterday, and did a quick check of my home theater space. I set the level to 70db using the pink noise, and then just did a quick check at the beginning of each track. I had nothing below 60db, and nothing significantly above 80db. From 100 Hz up, I don't think it varied more then 5db either side of 70. Does this mean I'm in pretty good shape, or do I really need to check each tone?
> 
> 
> -- Martin



I'm not trying to speak for Ethan, but +/-5dB is pretty "flat."


----------



## ctviggen




> Quote:
> The point about omnidirectional was a topic at HAA training and is based on when listeners can no longer pinpoint where sound is coming from. For most people this occurs below 125 hz. Thus a sub placed in any part of a room, with the crossover set to 125 hz or lower, should be impossible for a blindfolded person to point to. This has nothing to do with envelopment.



Based on my own tests, I simply do not believe this. I can EASILY point to a sub that's below 80 Hz (and even below 60 Hz). Get near 20Hz, then it becomes hard, but that's because I can no longer hear that frequency anyway.


----------



## Ethan Winer

Martin,


> just did a quick check at the beginning of each track.


----------



## CriticalListener




> Quote:
> Originally Posted by *ctviggen* /forum/post/0
> 
> 
> Based on my own tests, I simply do not believe this. I can EASILY point to a sub that's below 80 Hz (and even below 60 Hz). Get near 20Hz, then it becomes hard, but that's because I can no longer hear that frequency anyway.



That's quite impressive. While many studies have shown humans are incapable of localizing anything below 100hz, there are always people on the edge of the bell curves who are capable of amazing things.


----------



## Ethan Winer

Guys,


Often you can localize what seems like low frequencies by buzzes and rattles from nearby furnishings, and by distortion components that are well above the sub's crossover but still are emitted by the sub.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> That's quite impressive. While many studies have shown humans are incapable of localizing anything below 100hz, there are always people on the edge of the bell curves who are capable of amazing things.



[small voice]Maybe his sub rattles or has port noise.[/small voice]










edit: Sheesh, I should hit F5 more often. Ethan already covered this.


----------



## Sirquack




> Quote:
> Originally Posted by *ctviggen* /forum/post/0
> 
> 
> Based on my own tests, I simply do not believe this. I can EASILY point to a sub that's below 80 Hz (and even below 60 Hz). Get near 20Hz, then it becomes hard, but that's because I can no longer hear that frequency anyway.




ummmm yeahhhhh Ok


----------



## nowandthen




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> If your riser is buttkicker driven, it may not be very effective as a bass trap.



Would you please explain the principles of using a riser as a bass trap? I'd like to understand how it is done. Is it more trouble than it's worth? Or is it just not a good place to make a bass trap.


Also, you said if I had buttkickers it probably couldn't be done. I'd like to understand why.


Sorry about the noob questions.


----------



## pepar




> Quote:
> Originally Posted by *nowandthen* /forum/post/0
> 
> 
> Would you please explain the principles of using a riser as a bass trap? I'd like to understand how it is done. Is it more trouble than it's worth? Or is it just not a good place to make a bass trap.
> 
> 
> Also, you said if I had buttkickers it probably couldn't be done. I'd like to understand why.
> 
> 
> Sorry about the noob questions.



Well, when it comes to this, I'm a noob as well. But here's my explanation. For bass traps, one can use gobs (a highly precise and technical term) of fiberglass or a resonance absorber, a bass trap designed so that its mass has a resonance at the frequency (or band) that needs to be "trapped" (absorbed). The trouble frequencies strike it and excite it, and the bass energy at those frequencies is removed from the room and converted into motion. If your riser is being driven by a buttlicker, it will have its own agenda and won't be free to absorb energy.


Theoretically, a riser could be used as a trap, but the resonance would change as different people sat on it. To me, that would seem to remove it as a viable trap.


Check my link and go to the riser design & construction. I built it with adding Buttkickers (or Clark Synthesis) in mind, but the darn thing has a fortuitous vibration that seems to be centered at 25Hz. So, when something happening in the soundtrack around that frequency - a quite common occurance in LFE - the riser vibrates. Is it trapping those frequencies? Of course. But that's not what it's for. When the monsters stomp, my audience feels it. With the first movie I played after completing it - Jurassic Park - I realized I needed no Buttkickers.


I'm sure someone (on this thread!) could design a riser to be a trap or just vibrate at a certain frequency (band) for a passive buttkicer-effect. Me? I got lucky.


----------



## BasementBob

Pepar:



> Quote:
> Theoretically, a riser could be used as a trap, but the resonance would change as different people sat on it.



Think helmholtz.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Pepar:
> 
> 
> Think helmholtz.



Doh! Of course. It's called a "resonator" and not a "resonance absorber."


----------



## BasementBob

Two styles:

a) ported helmholtz -- with port in tri-corner (all modes active in tri-corners)

b) several 1/8" x ?foot long slots (cut with circular saw).


----------



## zductive

I have a 13' x 21' x8' dedcated theater. My acoustic treatment will be soffit absorbers plus 4" oc705 bass traps in the front corners. The rear wall opens at 50" high into a larger room.


I think that I want to coat the front wall with 1" oc703 spaced 2" off the wall. If I do this, should I frame each 2x4 piece and cover it with gom cloth? Should I wrap the poly bolster across the frame and into the space between boxes? OR, should I just mount the oc703 to the wall and tuft the gom at the corners of the insulation.


Can someone post a url to an example of a treated front wall.


Loking at this, I will have most of the oc703 behind the screen. I intend to mount the screen 6" off the wall with lightrope for illumination behind it.


I will also place one 2x4 panel at the sidewall reflection points.


Does this make sense? The room sounds reasonable now and has a large leather sofa 9' from the screen (92") I took car to space the speakers 3' from the side walls and the sub is 3' x 5' from the corner.


----------



## zductive

A little more info on the room.


Not to perfect scale.


The soffit would be 16" x 12 of oc703 along front and side walls.


dipole klipsch speakers are aligned with sides of sofa


92" screen

Any thoughts?

 

down sourh studio.pdf 24.5283203125k . file


----------



## pepar




> Quote:
> Originally Posted by *zductive* /forum/post/0
> 
> 
> I have a 13' x 21' x8' dedcated theater. My acoustic treatment will be soffit absorbers plus 4" oc705 bass traps in the front corners. The rear wall opens at 50" high into a larger room.
> 
> 
> I think that I want to coat the front wall with 1" oc703 spaced 2" off the wall. If I do this, should I frame each 2x4 piece and cover it with gom cloth? Should I wrap the poly bolster across the frame and into the space between boxes? OR, should I just mount the oc703 to the wall and tuft the gom at the corners of the insulation.
> 
> 
> Can someone post a url to an example of a treated front wall.
> 
> 
> Loking at this, I will have most of the oc703 behind the screen. I intend to mount the screen 6" off the wall with lightrope for illumination behind it.
> 
> 
> I will also place one 2x4 panel at the sidewall reflection points.
> 
> 
> Does this make sense? The room sounds reasonable now and has a large leather sofa 9' from the screen (92") I took car to space the speakers 3' from the side walls and the sub is 3' x 5' from the corner.



Check the theater construction at my link. My room is 13x21x8. And I have a 92" wide screen. I took a different route with a false wall.


I remember devouring members' websites when I was planning my theater whether theirs was what I wanted to have or not. Hopefully, you'll see something you like (or don't like) and that will help.


----------



## zductive

Thanks

I hadn't considered the false wall approach that you show. It looks like it may cut down on the construction time. However, it means that I will be doing more work inside the house.


Why did you select the 1" material over 2" oc703?


Did you find that the room was too dead when you finished?


----------



## pepar




> Quote:
> Originally Posted by *zductive* /forum/post/0
> 
> 
> Thanks
> 
> I hadn't considered the false wall approach that you show. It looks like it may cut down on the construction time. However, it means that I will be doing more work inside the house.
> 
> 
> Why did you select the 1" material over 2" oc703?
> 
> 
> Did you find that the room was too dead when you finished?



The cavity behind the wall is lined with 2" Johns-Manville Linacoustic. The first reflection point absorbers are made from 2" Owens Corning SelectSound Black. I have 2" 703 from which I am going to make Studiotips SuperChunks. Info on them and a WHOLE lotta data can be found here .


The room doesn't seem too dead, but I plan on taking some measurements when I start the trap project.


----------



## nowandthen

Thanks pepar and BasementBob. I think I'll forget trying to use the riser as a base trap. The two front corners are available as well as some soffit wall areas and floor wall areas.


----------



## KERMIE

I see that some people have their corner base traps starting on top of lets say a 7 inch high stage. When the base travels across the floor to into the corners does it hit the stage front which is usually wood/carpet and deflect? Newbie question...


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> I see that some people have their corner base traps starting on top of lets say a 7 inch high stage. When the base travels across the floor to into the corners does it hit the stage front which is usually wood/carpet and deflect? Newbie question...



That's not quite how bass frequencies "travel", but to keep it simple, they wash around something like a 7" stage like a _huge_ wave would.


----------



## bpape

The size of the waves you're talking about are huge compared to a 7" stage. Also, you can't generally think of bass waves like rays. The higher you get, the more sound acts as you would think - hit something and bounce off. Bass radiates as a sphere and more of a wavefront.


----------



## BasementBob

Objects significantly smaller than the wavelength are ignored by the wave.

Objects significantly large than the wavelength cause the wave to bounce off.
http://www.bobgolds.com/Diffusion/Di...nFrequency.GIF


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Objects significantly smaller than the wavelength are ignored by the wave.
> 
> Objects significantly large than the wavelength cause the wave to bounce off.
> http://www.bobgolds.com/Diffusion/Di...nFrequency.GIF



And in between?


----------



## BasementBob

pepar:


> Quote:
> And in between?



See the GIF link. Figure 4.2b.


Variations on this happen at the edges of free standing speakers (some diffusion in phase, some diffusion out of phase).


----------



## bpape

If the wave is even double the size of the object, it will pretty much ignore it. For a 7" height, that's up into the lower midrange.


Bryan


----------



## CriticalListener

Took the better part of two weekend, but I've finished two bass traps. After taking measurements (hopefully before summers out) I will decide if I need more bass traps. I did buy an extra box of insulation, so I'll just need the wood to build more.


I used my extra OC Acoustic Board {1" thick} on both sides to sandwich in the 4" of Knauff 6lb/ft insulation. Below is a picture of one, but the two are identical.


----------



## pepar




> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> Took the better part of two weekend, but I've finished two bass traps. After taking measurements (hopefully before summers out) I will decide if I need more bass traps. I did buy an extra box of insulation, so I'll just need the wood to build more.
> 
> 
> I used my extra OC Acoustic Board {1" thick} on both sides to sandwich in the 4" of Knauff 6lb/ft insulation. Below is a picture of one, but the two are identical.



Nice! How about a side view?


----------



## zductive

I am getting ready to build two bass traps for the front corners of my theater.

The extremely unprofessional forum thread on bass traps installation (now closed) raised many questions that I hadn't considered.


Experts - please clear this up possibly a moderated thread is in order


I want to build corner traps that have two layers of unfaced oc705. The top bottom and sides will be made from 3/4" mdf. I am treating the trap as if it were a pressurized vessel. That is, the seams will all be caulked and care will be made to ensure that the foam is held tightly against the box. This is all because of the "information" in the referenced thread.


I can not run the corner trap from the floor to the ceiling. It sits on a carpeted riser and has to terminate below the crown moulding.


I don't want to have to build this piece again! It would be much easier to frame out the drywall (single 1/2" layer) so that the oc705 would be held against the frame. I would then forget about the top and bottom also.


Based on current knowledge (the referenced thread insists that the bass traps must be held in proximate contact with the walls and the top and bottom must be in place to maintain the spring constant (at maximum) How does this type of trap really need to be fabricated??? Please don't refer to existing threads. I would like to get some yes/no information from ethan/bpape etc. No catfighting guys.


I don't care about sabines etc., what is your opinion about how the corner bass trap (not superchunk) should be fabricated!


Why was the raytracing method shot down out of hand.


----------



## BasementBob

zductive:


You could click on any of the links from "ChristianG's Corner Traps" on down at:
http://www.bobgolds.com/ 


Similarly on this page
http://www.bobgolds.com/AbsorptionCoefficients.htm 

any of the links between "Jon Risch's Absorbers" and "David French's absorption cloud design with aluminum guttering material"

should give you construction ideas.


And there's also ---k--- 's
http://racarris.com/HT/Corner%20Trap/ 

(with some text about it at
AVS Thread: Upgrades, Treatments & fun w/ ETF )

I think he ended up making three short corner traps and was reasonably content that he had done so. The reason I reference this thread, even though you asked not to, is you wrote


> Quote:
> I can not run the corner trap from the floor to the ceiling. It sits on a carpeted riser and has to terminate below the crown moulding.



and ---k--- both did that, and posted a bunch of good observations both human and ETF5 graphed.



> Quote:
> I am getting ready to build two bass traps for the front corners of my theater.



In an otherwise untreated room, I believe corner traps are an excellent LF bang for the buck/effort. All modes are active in tri-corners, so that's a good spot to put an absorber. (there are other alternatives to corner traps, but I'm unsure how to discuss them without using the temporarily evil 'Sabin' word.)



> Quote:
> I want to build corner traps that have two layers of unfaced oc705. The top bottom and sides will be made from 3/4" mdf. I am treating the trap as if it were a pressurized vessel. That is, the seams will all be caulked and care will be made to ensure that the foam is held tightly against the box.



Don't go gung ho on the sealing. If it has to be portable then simply glue and screw the wood (skip the acoustic caulk).



> Quote:
> I don't want to have to build this piece again! It would be much easier to frame out the drywall (single 1/2" layer) so that the oc705 would be held against the frame. I would then forget about the top and bottom also.



Sounds a bit like the Dave Portocarrero corner trap at http://www.bobgolds.com/TrapDave/home.htm (bottom two pictures).



> Quote:
> Based on current knowledge (the referenced thread insists that the bass traps must be held in proximate contact with the walls and the top and bottom must be in place to maintain the spring constant (at maximum) How does this type of trap really need to be fabricated???



Don't bother going gung ho sealing the edges. Just keep the absorber touching the sides if you can. If there's a 1/4" gap some places, don't worry about it. (A 2" hole is just being lazy - fix it).



And of course, last but not least
Studiotips Corner Absorber 


Anyway, building a corner trap is not rocket science. The main points are:

a) put 4" of rigid absorption on 2' diagonal as tall as you can and in as many corners as you can and touching the drywall.

b) Cover it with something fire retardant that'll keep the fibers in place when the wind blows on them. If your room has lots of HF absorption already consider something HF reflective, otherwise something you can breath through.

c) any framing you might do is simply to hold (a) and (b) in place.


If you can make observations of what you hear that's different, that's great.

We want pictures!


----------



## zductive

Thank you Bob for a very reasoned response.


It appears that there is a controversy about the need for the corner panel to come in contact with the corner walls. The discussion is confusing but, the safe way seems to have the glass touching the walls.


I con't think that my original idea of 3/4" mdf on the sides is required even though, it would make the corner reflector stiffer and less transparent to lower frequencies.


The compilation of various traps is great.


I will proceed with caution. Hopefully, I can make a few measurements from my listening position before I continue.


Biggest problem is integrating the corner trap into the remainder of the wall structure. I intend to have 2" oc703 spaced 2" from the walls. Since the corner trap is laid back into the corner, I guess that the best approach would be to have the oc703 run up to the point where it intersects the corner trap.



The problem that I am trying to address is the mismatch between speaker sound when I go through the alignment process. Each speaker sounds different. I believe that it is the result of the differences in high frequency reflections in the room. Time for sidewall reflection baffles!


Thanks for comments!


----------



## BasementBob

zductive:



> Quote:
> The problem that I am trying to address is the mismatch between speaker sound when I go through the alignment process. Each speaker sounds different.



(I'm not a fan of horizontal centers -- I don't care if the drivers are matched -- I prefer the fronts to be identical right down to the model number.)

In my basement I have three identical fronts that are good off axis, and four identical surrounds. There's a scene in Mission To Mars chapter 11, where the mission commander's voice goes through each of the 4 surround speakers one at a time in a seamless arc, as well as the three front speakers, demonstrating that all 7 speakers get individual signals with Pro Logic IIx -- and there's a big timbre mismatch between my fronts and my surrounds.

For my smaller HT I'm thinking of buying 5 identical speakers (two monopole surrounds).


Wall/floor/ceiling reflections (and SBIR) can make speakers sound different (because the reflections don't reflect all the frequencies evenly resulting in colouration) -- but I'm wondering if there's something different about your speakers themselves, or perhaps a blown driver.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> zductive:
> 
> 
> 
> (I'm not a fan of horizontal centers -- I don't care if the drivers are matched -- I prefer the fronts to be identical right down to the model number.)
> 
> In my basement I have three identical fronts that are good off axis, and four identical surrounds. There's a scene in Mission To Mars chapter 11, where the mission commander's voice goes through each of the 4 surround speakers one at a time in a seamless arc, as well as the three front speakers, demonstrating that all 7 speakers get individual signals with Pro Logic IIx -- and there's a big timbre mismatch between my fronts and my surrounds.
> 
> For my smaller HT I'm thinking of buying 5 identical speakers (two monopole surrounds).
> 
> 
> Wall/floor/ceiling reflections (and SBIR) can make speakers sound different (because the reflections don't reflect all the frequencies evenly resulting in colouration) -- but I'm wondering if there's something different about your speakers themselves, or perhaps a blown driver.



I completely agree. Using pink noise, a timbre difference can be noted among my three identical front speakers but it is MUCH smaller than it was when I had the so-called matched and dedicated center speaker from the same company. Position in the room and relationship to other objects will affect any speakers but it always is best to start out with a match. BTW, I could further reduce the discrepancy with Meridian MRC but the change was small.


Kal


----------



## zductive

klipsch towers on left and right.

left goes shii

right goes shewww


High frequency reflection is not the same for both speakers. Could it be the large pain of glass - you bet!


----------



## pepar




> Quote:
> Originally Posted by *zductive* /forum/post/0
> 
> 
> klipsch towers on left and right.
> 
> left goes shii
> 
> right goes shewww
> 
> 
> High frequency reflection is not the same for both speakers. Could it be the large pain of glass - you bet!



How does it sound with movies/music?


----------



## zductive

Sounds very good. No obvious distortion. Just annoying.


BTW - I did decide to go with the false wall approach that you show in your theater. Right now, I am trying to figure how I will bring the AC outlets to the front of the wall. Kind of tough if you bring the wall out 4" or more.


----------



## Monty Williams

I'm planning a remodel (mostly a change of furniture and surface treatments, i.e. change the color scheme of my GOM, carpet, and furniture) of my HT this fall/winter and wanted to get some feedback on if my acoustical treatments need to be readdressed. My room is used primarily for HD HT and HDTV, with minor usage for high resolution audio such as SACD/DVD-A.


I have attached a Visio of the current room which measures approximately 18' 5" x 24' 6" with 8', acoustical drop tile ceilings. Above the ceiling tiles, the ceiling joists are filled with 9" of rolled OC insulation.


I have a 110" Stewart GH RS on the front 18' 5" wall, and my primary seating position is about 11-12' away. The front wall is currently treated with 1" OC 703 from floor to ceiling. The side walls are treated similarly, except only the bottom 48" is treated, the top 48" or so is left untreated drywall. At the rear of the room a wet bar area is going to be built which is not shown in the Visio diagram, but there are no treatments currently on the rear wall.


The room is located in the basement, so behind all the walls is poured concrete. The external walls are standard 2x4 stud construction although they are staggered 1/2" away from the concrete. R13 insulation fills the void between the poured concrete and the inside of the drywall. The drywall is double layer/GG 5/8". The interior equipment closet at the rear left corner of the room is standard 2x4 with a single layer of 5/8" drywall with a Middle Atlantic Slim5 rack flush mounted with the wall as shown (a smoked plexiglass door covers the equipment). The floor is poured concrete with heavy padding and cut pile carpet.


L/C/R speakers are M&K S150 THX Ultra, SR/SL/SBR/SBL are M&K SS150 THX Ultra in tripole configuration. Subs are a pair of M&K MX350's controlled by a Velodyne SMS-1.


Any suggestions are appreciated.


----------



## pepar




> Quote:
> Originally Posted by *Monty Williams* /forum/post/0
> 
> 
> I'm planning a remodel (mostly a change of furniture and surface treatments, i.e. change the color scheme of my GOM, carpet, and furniture) of my HT this fall/winter and wanted to get some feedback on if my acoustical treatments need to be readdressed.
> 
> 
> I have attached a Visio of the current room which measures approximately 18' 5" x 24' 6" with 8', acoustical drop tile ceilings. Above the ceiling tiles, the ceiling joists are filled with 9" of rolled OC insulation.
> 
> 
> I have a 110" Stewart GH RS on the front 18' 5" wall, and my primary seating position is about 11-12' away. The front wall is currently treated with 1" OC 703 from floor to ceiling. The side walls are treated similarly, except only the bottom 48" is treated, the top 48" or so is left untreated drywall. At the rear of the room a wet bar area is going to be built which is not shown in the Visio diagram, but there are no treatments currently on the rear wall.
> 
> 
> The room is located in the basement, so behind all the walls is poured concrete. The external walls are standard 2x4 stud construction although they are staggered 1/2" away from the concrete. R13 insulation fills the void between the poured concrete and the inside of the drywall. The drywall is double layer/GG 5/8". The interior equipment closet at the rear left corner of the room is standard 2x4 with a single layer of 5/8" drywall with a Middle Atlantic Slim5 rack flush mounted with the wall as shown (a smoked plexiglass door covers the equipment). The floor is poured concrete with heavy padding and cut pile carpet.
> 
> 
> L/C/R speakers are M&K S150 THX Ultra, SR/SL/SBR/SBL are M&K SS150 THX Ultra in tripole configuration. Subs are a pair of M&K MX350's controlled by a Velodyne SMS-1.
> 
> 
> Any suggestions are appreciated.



Nice speakers; I have the same myself.


How does the system sound now? The best recommendation would be that you get some acoustical testing software and microphone and run some tests.


----------



## Monty Williams

Thanks. I really like M&K speakers and it continues to surprise me that they don't get talked about much here on AVS despite their use in movie/music studio monitoring and mastering.


I think my room sounds great now (better than it ever has), but the nature of this hobby is the endless pursuit of audio/video perfection. As much as we all like to think we've hit the nail on the head with our own HT, there's always room for improvement. Regardless of how many comparisons you do with other HT's/demo rooms/etc it's hard to say one is better than another unless there is an obvious problem due to our poor auditory memory. Plus you have all the other enthusiasts here commenting on their own rooms/HT's so it makes one wonder if there's more to be done.


While my room was built with HT in mind, there are some design/construction shortcomings and compromises. Your advice to have the room tested is a good one and I know that I should probably go ahead and do it, but I was just wondering if there were any glaring deficiencies that could be corrected prior to going that route in order to realize a more detailed assessment of my room's areas for improvement.


----------



## pepar




> Quote:
> Originally Posted by *Monty Williams* /forum/post/0
> 
> 
> Thanks. I really like M&K speakers and it continues to surprise me that they don't get talked about much here on AVS despite their use in movie/music studio monitoring and mastering.



I know what you mean, but I posted a thread on upgrading them and drew out a slew of M&K owners advising against it. I'm guessing that we're a smug bunch not needing approval from anyone else to know what we've got.











> Quote:
> I think my room sounds great now (better than it ever has), but the nature of this hobby is the endless pursuit of audio/video perfection. As much as we all like to think we've hit the nail on the head with our own HT, there's always room for improvement. Regardless of how many comparisons you do with other HT's/demo rooms/etc it's hard to say one is better than another unless there is an obvious problem due to our poor auditory memory. Plus you have all the other enthusiasts here commenting on their own rooms/HT's so it makes one wonder if there's more to be done.
> 
> 
> While my room was built with HT in mind, there are some design/construction shortcomings and compromises. Your advice to have the room tested is a good one and I know that I should probably go ahead and do it, but I was just wondering if there were any glaring deficiencies that could be corrected prior to going that route in order to realize a more detailed assessment of my room's areas for improvement.



Making changes to a room that "sounds great now" without acoustical measurements would be like . If it sounds that good already, there _may_ be a tweak that would improve it, but you're more likely to go backwards.


----------



## Monty Williams

Do you know my wife or something?










Seriously, I guess I need to qualify where I'm at now before I decide to make any changes.


----------



## Dennis Erskine

How do you know it sounds great?









The reason I say that is our hearing mechanisms are very good at adapting to "bad stuff" (the result is fatigue). I can't tell you the number of times we've been in "this room sounds great" but after we calibrate the comment is "I had no idea it was so bad."


I would strongly advise having a pro do some extensive measurements to see where you are at. These initial plots can target areas for improvement (if any) and give you something to compare once changes are made.


----------



## BasementBob

Dennis Erskine:



> Quote:
> The reason I say that is our hearing mechanisms are very good at adapting to "bad stuff" (the result is fatigue). I can't tell you the number of times we've been in "this room sounds great"



My mother says in the same breath "I don't know why you spend so much time thinking about acoustics. My living room sounds great. BTW, thanks for the new DVD player. I really like the subtitles button. When I can't understand what they're saying I can just rewind and read it."


----------



## Monty Williams




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> How do you know it sounds great?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The reason I say that is our hearing mechanisms are very good at adapting to "bad stuff" (the result is fatigue). I can't tell you the number of times we've been in "this room sounds great" but after we calibrate the comment is "I had no idea it was so bad."
> 
> 
> I would strongly advise having a pro do some extensive measurements to see where you are at. These initial plots can target areas for improvement (if any) and give you something to compare once changes are made.



You're right, as I mentioned my assessment of my HT is entirely based upon my limited experience with my previous environments and comparisons with other rooms (albiet admittedly via ear/auditory memory - also admittedly faulty at best ). I know my room is not perfect, possiblty not even ideal, hence my post here and interest in improving my situation. My area of expertise has nothing to do with this hobby or interest.


I'm all for having a "pro" come in and do measurements, I'm just wondering if there are any basics or otherwise glaring omissions I've missed prior to going through that exercise so that I can make it more meaningful be alleviating flagrent issues and focus more on "fine tuning".


If however, the proper starting point is simply starting with whatever you have whether it be a raw room or a room treated in any way, then that would be an appreciated suggestion as well.


Recommendations for the NW suberbs /North Shore of Chicago would be appreciated as well.


----------



## BasementBob

Monty Williams


You might enjoy having a look at this: Sencore 10 Steps to Optimized Sound


----------



## Dennis Erskine

Here's some starts:


LF/RF too far apart for imaging and sound stage

LR/RF too close to side and front walls (SBIR)

One of two subwoofers are mis-located

Rear surrounds have timbre mismatches

Where is the center channel with respect to the screen?

Center channel too close to front wall


----------



## Monty Williams

Thanks Bob,


There's some good info there - some of which I've already considered and implemented, but some which I haven't. I think the responses to my initial and follow up posts confirm that if I want to quantify my efforts then I need to establish a baseline with what I have now.


However, I must point out that I can't recall a thread on this forum where someone had their room measured in raw form, incorporated the recommendations, and then remeasured after the the suggested corrections were made. I'm sure there have been some, but if anyone can point them out I'd be very appreciative.


I've been entertaining the idea of THX, Alpha, or the like, certification for about a year now, and I am most interested in pursuing it this fall/winter.


----------



## Monty Williams




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Here's some starts:
> 
> 
> LF/RF too far apart for imaging and sound stage
> 
> LR/RF too close to side and front walls (SBIR)
> 
> One of two subwoofers are mis-located
> 
> Rear surrounds have timbre mismatches
> 
> Where is the center channel with respect to the screen?
> 
> Center channel too close to front wall



Okay, what do I need to do to get more detailed information from you, i.e. let's talk about consultation. PM or email would probably most appropriate at this point I'm assuming.


However, I must quickly ask for clarification on one point though - Why would the rear surrounds have "timbre mismatches" when they are the exact same speaker as the side surrounds and all the tweeters are the same/timbre matched according to M&K?


Again, if it is appropriate to contact you via email/PM or via telephone please let me know. I'd like to get my remodel going this fall.


----------



## BasementBob

Monty Williams:



> Quote:
> However, I must quickly ask for clarification on one point though - Why would the rear surrounds have "timbre mismatches" when they are the exact same speaker as the side surrounds and all the tweeters are the same/timbre matched according to M&K?



If the side surrounds are the same as the fronts, right down to the model number, then ignoring reflections and broken drivers/cones, they're as good a timbre match as you're going to get.


If the side surrounds have the same size drivers/cones as the fronts, but the speaker cabinets are different, or the configuration of the drivers (e.g. two midrange vs one midrange) is different, then there's a strong chance they are not timbre matched.


To try it yourself, throw in a copy of Mission To Mars and go to chapter 11. The sound of one man's voice is paned slowly through all speakers. With my setup it's easy to hear a difference between the fronts and the rears. I have three identical fronts, right down to the model number (no horizontal center).


----------



## BasementBob

Monty Williams:



> Quote:
> However, I must point out that I can't recall a thread on this forum where someone had their room measured in raw form, incorporated the recommendations, and then remeasured after the the suggested corrections were made.



Alpha Certification example:
Building the Music Vault - part 1 , part 2 , and part 3 .

AVS thread: ---k---'s Upgrades, Treatments & fun w/ ETF -- not the whole 9 yards, but it was the first one I thought of.


----------



## Monty Williams




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Monty Williams:
> 
> 
> 
> 
> If the side surrounds are the same as the fronts, right down to the model number, then ignoring reflections and broken drivers/cones, they're as good a timbre match as you're going to get.
> 
> 
> If the side surrounds have the same size drivers/cones as the fronts, but the speaker cabinets are different, or the configuration of the drivers (e.g. two midrange vs one midrange) is different, then there's a strong chance they are not timbre matched.



All four surrounds are exactly the same, same model, same part number etc. The onle difference is the orientation each is facing so that the phase is correct. The surrounds are M&K's recommended match for the S150 L/C/R's (as well as the subs) I'm using. There is no mismatch, at least according to M&K, within my speaker system.


Obviously placement and room acoustics affect it afeter the fact, hence the purpose of my posts.


----------



## BasementBob

Monty Williams:



> Quote:
> All four surrounds are exactly the same, same model, same part number etc.



I meant are your four surrounds the same as your three fronts.



> Quote:
> The surrounds are M&K's recommended match for the S150 L/C/R's (as well as the subs) I'm using. There is no mismatch, at least according to M&K, within my speaker system



I think this means the answer is no. The surrounds are different from the fronts.


To tell if they are timbre matched, try Mission To Mars.


----------



## Dennis Erskine

Timbre mismatch is due to the close proximity of the left rear surround to the side wall as contrasted to the distance of the right rear surround from any side boundry.


We can do a THX Certified Home Theater. Alpha Certification is Terry's domain.


----------



## Ethan Winer

Monty,


> I can't recall a thread on this forum where someone had their room measured in raw form, incorporated the recommendations, and then remeasured after the the suggested corrections were made.


----------



## nowandthen




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Monty Williams
> 
> 
> You might enjoy having a look at this: Sencore 10 Steps to Optimized Sound



From step 2 "Front L & R Main Speakers


Form an equilateral triangle with the center of the listening area


Locate at least 3 feet from walls


Position about 1/4 of room width from side walls & 1/4 of room length from front wall"


Realistically, how many of us have the room to do this, or perhaps should I say the desire to do this? In my 24' long room, according to this I need to place my fronts 6' out from the front wall. Therefore my AT screen needs to be 7' from the front wall. My 24' room is now effectively 19' long. Are there solutions to this ideal situation that won't eat up 1/4 of my room? e.g front wall treatments.


Thanks,


Todd


----------



## bpape

Remember the title "OPTIMIZED sound" (in their opinion). It says nothing about real world rooms or practical solutions. Unfortunately, there is no one perfect way to set up every speaker in every room.


Basic rules of thumb:


- Maintain symmetry left to right in front of you.

- Dont' put any speaker or any seat right up against a wall

- Place the seating first and let it guide the rest of the setup

- The equilateral triangle is a decent starting point but be willing to move from there.

- Be willing to treat the walls if the speakers (front) need to be placed close to the walls because you bought too big a screen or you have a very long narrow room.

- Set your speakers to small and let the sub handle the bottom. This lets you move the sub for best response without messing up imaging. The best place for your mains is almost never the best place for bass response.


Pretty much everything else is unique to a specific situation.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *nowandthen* /forum/post/0
> 
> 
> From step 2 "Front L & R Main Speakers
> 
> 
> Form an equilateral triangle with the center of the listening area
> 
> 
> Locate at least 3 feet from walls
> 
> 
> Position about 1/4 of room width from side walls & 1/4 of room length from front wall"
> 
> 
> Realistically, how many of us have the room to do this, or perhaps should I say the desire to do this? In my 24' long room, according to this I need to place my fronts 6' out from the front wall. Therefore my AT screen needs to be 7' from the front wall. My 24' room is now effectively 19' long. Are there solutions to this ideal situation that won't eat up 1/4 of my room? e.g front wall treatments.
> 
> 
> Thanks,
> 
> 
> Todd



I've never seen a theater where LCR are that far from the front wall. Mostly, they are a few feet out or mounted ON the wall. Mine are like that, but I've treated the front wall with 2" J-M Linacoustic and am planning to add bass traps there as well.


----------



## Dennis Erskine

If your mains are crossed over with the sub(s) at 80Hz, the mains would be about 3.5' from the front wall. Since this isn't a practical solution in most cases, the front wall needs to be treated with a combination of absorption and diffusion to diminish boundary effects.


----------



## Andrew Hornfeck

WHAT would you suggest I use to attach 2' x 2' "accent" panels built of 1-1/2" Knauff board to my walls which are also made of GOM-covered Knauff panels. Does Velcro work? How about some kind of spike strips? Where can I buy them?


----------



## Kal Rubinson

You can buy spike strips cheaply at Home Depot. Also, take a look at the various models of RotoFast fasteners at http://www.rotofast.com A little pricey but elegant and effective.


Kal


----------



## Andrew Hornfeck




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> You can buy spike strips cheaply at Home Depot. Also, take a look at the various models of RotoFast fasteners at http://www.rotofast.com A little pricey but elegant and effective.
> 
> 
> Kal



THANKS for the quick reply!


When you say spike strips, are you speaking of the mending plates they sell in the lumber/truss section or something else?


I'd never seen these Rotofast jobs -- I'm (essentially) attaching one panel TO another, so only the double one would work. That's why I was looking into the spikes or velcro.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Andrew Hornfeck* /forum/post/0
> 
> 
> THANKS for the quick reply!
> 
> 
> When you say spike strips, are you speaking of the mending plates they sell in the lumber/truss section or something else?



Yup.


Kal


----------



## pepar




> Quote:
> Originally Posted by *Andrew Hornfeck* /forum/post/0
> 
> 
> THANKS for the quick reply!
> 
> 
> When you say spike strips, are you speaking of the mending plates they sell in the lumber/truss section or something else?
> 
> 
> I'd never seen these Rotofast jobs -- I'm (essentially) attaching one panel TO another, so only the double one would work. That's why I was looking into the spikes or velcro.



Spike strips = I think are used to install carpet and are installed around the room's perimeter.


----------



## BasementBob

Kal Rubinson:


The rotofast looks cool -- I like that it can be used THROUGH fabric.


This is what I've done before: http://www.bobgolds.com/AbsorberMount/home.htm


----------



## Kal Rubinson




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Kal Rubinson:
> 
> The rotofast looks cool -- I like that it can be used THROUGH fabric.
> 
> This is what I've done before:



Nice. BTW, I used plastic stand-offs with the Rotofasts to space the panels off the wall.


Kal


----------



## CriticalListener




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> The rotofast looks cool -- I like that it can be used THROUGH fabric.



It looks so cool I emailed the company. Then I got back a Mail Delivery Error for [email protected] , which cools my enthusiasm as I have to question their competence in either putting up the wrong email address or choosing a bad internet provider or, worst case scenario, failure to pay some bills.


----------



## Kal Rubinson

That address has worked for me. I understand your feeling but perhaps you might try again.


Kal


----------



## kiwishred

Based on what I have read in this thread I was contemplating making sound absorbers by placing a single 2'*4'*2" OC 703 panel in a 3" deep frame so it would be held out from the wall by 1". 3" total depth is as much as I want to go for aesthetics reasons.


However, the first source I have found for OC 703 in Seattle, R-Factor, only has 1" sheets. So, the questions I have are these:


1) If I stack two 1" sheets do I have the acoustic equivalent of a 2" sheet ? Is it necessary for them to be pressed tightly together to achieve this ? I am inclined to think so because, otherwise, some sound passing through the first sheet might reflect off the second sheet and therefore not get absorbed in the second sheet...


2) For a 3" total frame depth, rather than have 2" 703 + 1" back air gap, am I better off using 3" 703 and no air gap ? Use of 1" 703 allows this possibility whereas 2" panels do not.


BTW, here are some sources for unfaced, 2'*4'*1, 3 pfc density, rigid fiberglass in the Seattle area (who will sell to the public):


R-Factor, 16750 Woodinville-Redmond Rd. Woodinville. 425-488-7600.

Owens Corning 703, $145 per pack of 24 sheets (192 sq feet). 75.5 c/sq foot


Bay Insulation, 7043 S 190th St, Kent. 425-251-6750.

Owens Corning 703, Sell by the sheet, 64 c/sq foot.


E J Bartells, 700 Powell Ave SW, Renton, 425-228-8807.

Johns Manville 814 "SpinGlas" (same acoustic specifications as Insul-SHIELD I/S 300 but targeted at duct insulation rather than general construction), $63.36 per pack of 18 sheets (144 sq feet). 44 c/sq foot


Note: "SpinGlas/Insul-SHIELD has nominally better absorption ratings than OC 703, eg:











However, I suspect this might just be measurement variability.


Brent


----------



## BasementBob

kiwishread



> Quote:
> 1) If I stack two 1" sheets do I have the acoustic equivalent of a 2" sheet ?



Yes.



> Quote:
> Is it necessary for them to be pressed tightly together to achieve this ?



No.

However, it's better to have them pressed together so that they are both out from the wall as far as possible within that 3".



> Quote:
> I am inclined to think so because, otherwise, some sound passing through the first sheet might reflect off the second sheet and therefore not get absorbed in the second sheet...



Don't worry about it.



> Quote:
> For a 3" total frame depth, rather than have 2" 703 + 1" back air gap, am I better off using 3" 703 and no air gap ?



Yes, but not much.


----------



## RyanJNielson

Hey, guys-


I'm building my dedicated HT room and have a question:


The room is 8 x 12.5 x 17.5 and I am planning to line my side walls with 1" Linacoustic RC (up to ear level). I am also planning to cover the front wall (floor to ceiling) with 1" of the Linacoustic. With a 100' roll, I'll still have about 40' of Linacoustic left over.


My question is this:


Would it be feasable to cut the Linacoustic into triangles and stack them floor to ceiling to provide some rear-room bass absorption?


I am planning some good sized superchunk style front-room bass absorption using 5.5" acoustical cotton.


What do you think...?


----------



## jandawil




> Quote:
> Originally Posted by *RyanJNielson* /forum/post/0
> 
> 
> Hey, guys-
> 
> 
> I'm building my dedicated HT room and have a question:
> 
> 
> The room is 8 x 12.5 x 17.5 and I am planning to line my side walls with 1" Linacoustic RC (up to ear level). I am also planning to cover the front wall (floor to ceiling) with 1" of the Linacoustic. With a 100' roll, I'll still have about 40' of Linacoustic left over.
> 
> 
> My question is this:
> 
> 
> Would it be feasable to cut the Linacoustic into triangles and stack them floor to ceiling to provide some rear-room bass absorption?
> 
> 
> I am planning some good sized superchunk style front-room bass absorption using 5.5" acoustical cotton.
> 
> 
> What do you think...?



That would be a lot of cutting if you used 1" material as opposed to 4", plus to my knowledge linacoustic is not very dense. You want something more dense that will give you better absorbtion at the lower frequencies such as OC703 or in my case I used Roxul mineral wool. It was only $78 for enough to do 8' high corner traps 24" across. I'm sure others more knowing than I will also pipe in


----------



## RyanJNielson

Thanks for the tip, Jon-


Rockwool seems to be a great solution for my corners. VERY economical!


Great job on your theater, btw!


----------



## jandawil




> Quote:
> Originally Posted by *RyanJNielson* /forum/post/0
> 
> 
> Thanks for the tip, Jon-
> 
> 
> Rockwool seems to be a great solution for my corners. VERY economical!
> 
> 
> Great job on your theater, btw!



Thanks man!!! It's always a work in progress but I'm really enjoying it. Good luck with your project.


----------



## nowandthen




> Quote:
> Originally Posted by *Bpape* /forum/post/0
> 
> 
> Remember the title "OPTIMIZED sound" (in their opinion). It says nothing about real world rooms or practical solutions. Unfortunately, there is no one perfect way to set up every speaker in every room.
> 
> 
> ....





> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I've never seen a theater where LCR are that far from the front wall. Mostly, they are a few feet out or mounted ON the wall. Mine are like that, but I've treated the front wall with 2" J-M Linacoustic and am planning to add bass traps there as well.





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> If your mains are crossed over with the sub(s) at 80Hz, the mains would be about 3.5' from the front wall. Since this isn't a practical solution in most cases, the front wall needs to be treated with a combination of absorption and diffusion to diminish boundary effects.



Thanks Bryan, pepar and Dennis. I knew the 6' from front wall was not realistic for most people. I'm glad to heat the experts have "ways" to compensate.


Todd


----------



## pepar




> Quote:
> Originally Posted by *nowandthen* /forum/post/0
> 
> 
> Thanks Bryan, pepar and Dennis. I knew the 6' from front wall was not realistic for most people. I'm glad to heat the experts have "ways" to compensate.
> 
> 
> Todd



FYI, the other two are experts.


----------



## zductive

Can anyone direct me to a diy for an acoustic soffitt??


I am planning to install a 16w x 10 h " soffit made from oc703 material and wrapped in gom. The soffit will wrap across the front stage and then down the two sidewalls.


If I am lucky, I can incorporate a hushbox into an extension of the soffitt across the room at the projector location.


I am having a little trouble determining what the internal structure of the soffit should be. Also having a little trouble with how the edge away from the wall should be supported.


The soffitt will be a little heavier because I am going to install miniature downlights from HD (low voltage).


----------



## BasementBob

zductive:


There's a bunch of ways.


Here's one:

- Build a bunch of downward struts on 2' centers.

- Then build a ladder (two 12' 2x2's with 13" 2x2's across on 2' centers)

- add extra cross pieces (ladder steps) where the lights will go.

- Then screw the ladder to the downward struts.

- build wood boxes lined with drywall for the lights, and put them in place

- wire the lights, and run any speaker wire or other wires you intend to use

- run any HVAC ducts you want to run.

- Fill it with 703 (notches optional, duct stocks cuts optional, put them in diagonally, turn them upright).

- Cover it with GoM

- Add trim over the staples.


Another variation:

- build two ladders (two 12' 2x2's with 7" 2x2's across on 2' centers)

- turn it into a box frame by adding more 7" 2x2's to join the ladders

- fasten it to the walls and ceiling.

-


----------



## zductive

Bob - your on the right track but, I was thinking more about the soffit bass traps that ASC sells http://www.asc-home-theater.com/products-soffit2.htm .


What does the internal structure of that trap look like?


It looks like it is two pieces of oc703 wrapped in cloth. What I can't see is how the two pieces are held together structurually and what the track looks like.


Any ideas?


T


----------



## Scott Mat

I have a small room in my basement that I am considering adapting to use as a HT. It has sheetrock walls and a drop ceiling. Should I re-sheetrock with green glue? What can be done about the ceiling and floor (carpet over concrete)?


Thanks,


Scott


----------



## BasementBob

zductive:


I don't know. You could buy 2' of them and find out.

I'm guessing it's foam; eor two pieces of 703, each fully wrapped in GoM, with 90 degree bent clothes hangers, and glue on the join.


However, if you want to build it that way (hollow inside), you could try a variation on this with sheet metal or aluminum guttering as framing: http://www.recording.org/ftopict-26889.html


----------



## BasementBob

Scott Mat:

That sounds to me like a question for your own separate thread.


----------



## kiwishred

Is speaker cloth (specifically the black polyester variety that can be had from Joann fabrics for about $7 per 60" wide yard) sufficient to contain all the nasties that might potentially flake off rigid fiberglass ?


I have seen some people add a layer of batting but then others just wrap their naked OC 703 in nothing but burlap. So I am wondering if the batting is really necessary or just an extra precaution for the sake of peace of mind ...


TIA,

Brent


----------



## myfipie

IMO it is just a extra precaution. I have never heard of fiberglass even leaking out of burlap. Now if you HIT the panel with a bat I am sure something would come out.


Glenn


----------



## nirvana_av




> Quote:
> Originally Posted by *kiwishred* /forum/post/0
> 
> 
> Is speaker cloth (specifically the black polyester variety that can be had from Joann fabrics for about $7 per 60" wide yard) sufficient to contain all the nasties that might potentially flake off rigid fiberglass ?
> 
> 
> I have seen some people add a layer of batting but then others just wrap their naked OC 703 in nothing but burlap. So I am wondering if the batting is really necessary or just an extra precaution for the sake of peace of mind ...
> 
> 
> TIA,
> 
> Brent



I have had success using the very thin, dark gray fabric similar to what you will find covering the bottom of upholstered chairs and sofas. I attach it to the fiberglass using 3M Super 77 spray adhesive. The fiberglass panel is then inserted into a GOM wrapped wood frame. This provides one more containment for the fibers if you are concerned. On the other hand, I've also applied GOM directly to OC705 and I haven't seen any evidence of fibers coming through.


----------



## chillinintheoc

I need to buy some 1" Linacoutsic...how much is that stuff for a roll?



chillinintheoc


----------



## KERMIE

Was it ever really decided if a corner bass trap Floor to ceiling is better as a:


1. 24 inch triangle filled with wedges of acoustical cotton from top to bottom


or


2. Roughly 3-4 " thick just across the face and a 45 degree angle, a space from there to the wall corner.



In my room I wanted to do 4 corner base traps floor to ceiling but I can only do the back two walls. The front corners have a corner trap, floor up to 52" then a tri corner by the ceiling.


I still have to do the back corners and wanted to know the best solution.


Room is 13 x 17


thanks


----------



## Stima

Good question...I don't recall any definitive comparisons. I am eager for a reply as well.


----------



## bpape

If all else is equal, the solid ones will reach a bit deeper into the bottom end more effectively. In effect, you'll use the same amount of material to do a solid one as you would to do a 6" thick straddling panel.


Bryan


----------



## myfipie




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> If all else is equal, the solid ones will reach a bit deeper into the bottom end more effectively. In effect, you'll use the same amount of material to do a solid one as you would to do a 6" thick straddling panel.
> 
> 
> Bryan



And you will take up far less room.


Glenn


----------



## GetGray

Can you elaborate, I'm not following. Do you mean the solid triangle literally in the corner is more effective than the panel straddling the corner? If it's less material and more effective, why wouldn't everyone do it that way?


----------



## pepar




> Quote:
> Originally Posted by *GetGray* /forum/post/0
> 
> 
> Can you elaborate, I'm not following. Do you mean the solid triangle literally in the corner is more effective than the panel straddling the corner? If it's less material and more effective, why wouldn't everyone do it that way?



I think I picked up that the same amount of material is used as in a *6"* "straddling" type. Previously, the cross-corner style with a 3"-4" thick panel had been discussed.


----------



## bpape

Yes. If you do the solid chunk, you're going to have a 17x27x24" corner with the farthest part being out 12" from the corner at 45 degrees.


If you have a 6" thick panel (2' wide and framed so about 25.5") straddling the corner, the BACK of that panel will be at 17" (along the wall) from the corner - 12" out at 45 degrees. From there, it will stick out another 6".


In addition, for the same amount of upper bass, mid and HF absorbtion, you'll get slightly better really deep bass control.


Bryan


----------



## GetGray




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> ... 17x27x24" corner with the farthest part being out 12" from the corner at 45 degrees.



You meant 17x17x24 I presume.


> Quote:
> In addition, for the same amount of upper bass, mid and HF absorbtion, you'll get slightly better really deep bass control.



to be sure I am clear, you meant slightly better when using the solid design.[/quote]Let me know if I have that incorrect. Thanks for the clarification.


----------



## pepar




> Quote:
> Originally Posted by *GetGray* /forum/post/0
> 
> 
> You meant 17x17x24 I presume. to be sure I am clear, you meant slightly better when using the solid design. Let me know if I have that incorrect. Thanks for the clarification.


 Corner Absorption Comparision test


----------



## GetGray

That appears to show foam outperforming the fiberglass. Thought the foam wasn't so good realtive to the FG?


----------



## pepar




> Quote:
> Originally Posted by *GetGray* /forum/post/0
> 
> 
> That appears to show foam outperforming the fiberglass. Thought the foam wasn't so good realtive to the FG?



I think the point of the test was to show that the DIY SSC (Studiotips Super Chunk) performed nearly identical to a commercial bass trap.


----------



## Meddy

A quick question for the experts. I have just completed framing out my basement and had to box-in two I-beams with the heating ducts in between (8' span). This "box " hangs approx 1' down from the ceiling,and is 14' wide (width of room) The two faces of the box are approx 12" high, 6" deep from face of 2x4's to the I-beam. Is it of any benefit to stuff this opening with Safe and Sound and cover with GOM and use as two bass traps, even though the trap wouldn't straddle the ceiling/box intersection? I plan on two super chunk style bass traps from floor to ceiling at the back of room (room is 29' long) and wondered if the 2 faces of the box would add anything or should I just drywall over them. Thanks


----------



## KERMIE

I have a question on my wall treatment bottom half.


I am using a 1" acoustical cotton behind GOM with 1 1/4" frames to keep it a little off the wall.


After I put the frames up it seems like the padding is not touching the GOM and I am afraid that it is laying up against the wall.


My concern is that when you push on the GOM it is just tight fabric and you have to push down hard to feel the padding.


I know most of the HT's that I have been in when you push on the walls it is like a firm mattress like feel. What am I going to experience in the future with sound and GOM issues..?


thank you


----------



## bpape

If you're using 1" cotton with only 1/4" behind it, it really doesn't matter. That 1/4" won't make diddly difference. If you want a nice padded feel (for those that must poke walls...), put a 1/4" slat across the back at 1/4, 1/2, and 3/4 of the height of the panel.


Bryan


----------



## Stima

I went the other route. Since fiberglass panels measure nearly exactly 1" thick...I made "picture frames"on my walls using long pieces of 1.5" x 8' x .75" boards with 1.5"x 1.5" x 1/4" cut spacers\\shims. Instead of running the 1/4" material the full length behind the .75" material, I only placed the spacers\\shims where I nailed gunned through the into a stud. On pieces that didn't have a stud to nail, I put in drywall anchors and used screws. This required drilling through holes in the wood, but it worked almost as well as the nail gun nails into studs.


After the frame was up and the fiberglass installed, I then stretched GOM from frame piece to frame piece over the fiberglass. For each wall, I ran two pieces of GOM the of the length of the wall room. (Two pieces since GOM is 64" wide and my room was 96" high.) This left GOM "seams" at each frame piece which I covered with stained wood "chair rail" pieces, floor board, and crown molding.


Whatever you do...do NOT try and use cotton batting in places you don't have acoustical cotton. The batting will NEVER maintain the same "thickness" and your eye will ALWAYS know where the two materials are different. If I had to do it over, I would simply put drywall or particle board in the places I didn't use fiberglass to maintain the proper depth.


----------



## tek-noid

After calling a dozen+ "local" (within 100 miles) HVAC distributors, I've had no luck finding Linacoustic, Insulshield, etc. I do have a line on "Knauf Wall & Ceiling Liner M", but all I know of its properties are a 1.5 PCF and a NRC of 0.70.


Q1. Does anybody know if this is a suitable replacement for Linacoustic, 703, etc?


Q2. I've asked this dealer (as well as an e-mail to Knauf) what the Absorption Coefficients are for this material, as they aren't posted on the website. Of course, I don't know what do with this info when/if I get it. If I compare this data with comparable product data from http://www.bobgolds.com/AbsorptionCoefficients.htm , what tolerances are acceptable?


Thanks,

James


----------



## Terry Montlick

Hi James,


This is a tough call, because "suitable replacement" is hard to define. Most home theaters are (unfortunately) not designed to particular acoustical specifications. If I had designed and modeled a theater which *required* 2.25-3 pcf fiberglass, then 1.5 pcf would not be a suitable replacement.


Knauf's published absorption coefficients for this product are:


1.5 PCF 1" .18 .36 .59 .86 .95 .90


However, there is also a 2 pcf version with the following published absorption coeffficients:


2.0 PCF 1" .25 .35 .69 .89 .96 1.01


If your supplier can get the 2 pcf Knauf, I would use that instead. BTW, I don't rely on any single set of reported absorption coefficient measurements, since the reverberation room method has a pretty high margin of error. We have our own proprietary absorption coefficent database.


Regards,

Terry


----------



## Felgar

This is a question on the general principles of sound absorbtion, as I find I'm usually better able to understand real-world situations by first understanding the underlying scientific/physical mechanisms in play.


I'm wondering what is it about a material that makes it able to absorb a sound wave. It is known that 3" of pink fiberglass will pretty much absorb all of the sound at 10,000 Hz, but very little at 40 Hz. Why is this? What is it about the higher frequencies that make them able to be absorbed by insulation (or ANY material for that matter), and what is it about lower frequency sound that enables it to pass right through insulation without being touched?


These questions drive a desire for me to understand how to effectively treat a room for appropriate bass atenuation, and it comes as a result of a conversation I has with a dealer about room accoustics. Intuitively it made sense to me that a thicker material might be needed in order to absorb a longer wavelength (lower frequency) sound wave. So I was asking the dealer how much of a corner will a bass trap that's effective down to 50Hz take up? Like, will a triangle of pink insulation in the corner that spans a distance 18" out from the corner on each wall work?


The response I got is that sound absorbtion is much more dependent on mass than shape. So I got to wondering, could a 1 or 2" thick panel in the corner work as a bass trap if it was heavy enough? Can a 1" thick layer of sand (being very heavy) over a wall effectively absorb the low frequency sound hitting the wall? One of the heaviest foams I know of comes in the form of those blue foldout gymnastic mats... Maybe that material could make an effective low frequency absorbtion material...


----------



## Terry Montlick




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> I'm wondering what is it about a material that makes it able to absorb a sound wave. It is known that 3" of pink fiberglass will pretty much absorb all of the sound at 10,000 Hz, but very little at 40 Hz. Why is this?



There's more going on than the following description, but a simple explanation of absorption in porous material like fiberglass involves material thickness vs. wavelength. A material can only absorb sound if its depth is at least some reasonable fraction of a wavelength (like 1/8).


To get the wavelength in feet of any frequency, divide 1000 (speed of sound) by that frequency. So a 10,000 Hz wave has a wavelength of 1/10 ft ~= 1". 3" fiberglass is 3 wavelengths thick, and has no trouble absorbing this sound.


A 40 Hz wave has a wavelength of around 1000/40 = 25 feet = 300". The 3" fiberglass is only 1/100 of this wavelength, so it can do very little to absorb it.


Regards,

Terry


----------



## Felgar

Ok, that's exactly what I was wondering, and is also more in line with what my intuition was telling me originally... So lets say pink fiberglass can absorb frequencies of wavelengths up to about 8 times its thickness. So 3" might absorb well until about a 24" wavelength, or a frequency of 500 Hz. Would putting it on a wall work to double the effectiveness because the wave has to travel in and then back out after reflecting off the wall?


And can I assume that different materials will have different properties for effectiveness? Like, maybe the special insulation that's supposed to improve sound isolation may be able to absorb 10 or 12 times it's thickness instead of just 8?


And of course, is there any documentation that can be found on what materials work in what way?


----------



## Ethan Winer

Felgar,


To expand on Terry's explanation a bit:


The _reason_ fiberglass absorbs best when a substantial portion of the wave fits within its thickness is because "porous" absorbers like fiberglass act on wave velocity. If you picture a sine wave in your mind, the portion where the wave is all the way at the top or bottom has more velocity (greater absolute level) than the portions near the center.


When a sound wave hits a room boundary the velocity is zero at that point, and rises as you get farther from the wall. At 100 Hz the wave achieves maximum velocity 34 inches away from the wall. At 1000 Hz the maximum is only 3.4 inches away. So fiberglass four inches thick appied to the wall will absorb 1000 Hz completely, but at 100 Hz the wave has barely gotten started, so to speak, so there's not much to absorb.


I think of porous absorbers as working sort of like a person trying to run through chest-high quicksand. If you don't try to walk too fast you can slog your way through it. But the faster you try to go, the more friction is created and the harder it is to proceed. Fiberglass (and acoustic foam and rock wool etc) all work by creating the same sort of friction, but in this case for sound waves.


> Would putting it on a wall work to double the effectiveness because the wave has to travel in and then back out after reflecting off the wall?


----------



## kiwishred

Ethan -


You could have saved some typing by quoting your own excellent article on the subject







. Also, I found this article describing different types of absorbers, including porous.


Let me add a couple of speculations:


- I think you actually mean the _particle velocity_ not the _wave velocity_, no ? The distinction being that the wave velocity is an intrinsic property of the propagation medium (it is a constant for a given material, temperature, etc) whereas the particle velocity is extrinsic (it varies in space and time) and describes how fast the air molecules themselves are moving.


- The problem with using a high density material is getting the sound to get into it in the first place. If it is too dense then too much of the sound will be reflected from the front surface and it won't matter how good an absorber it is.


I say speculation above because I am still in the process of digesting all the information in this thread myself.


Brent


----------



## Terry Montlick




> Quote:
> Originally Posted by *kiwishred* /forum/post/0
> 
> 
> Let me add a couple of speculations:
> 
> 
> - I think you actually mean the _particle velocity_ not the _wave velocity_, no ? The distinction being that the wave velocity is an intrinsic property of the propagation medium (it is a constant for a given material, temperature, etc) whereas the particle velocity is extrinsic (it varies in space and time) and describes how fast the air molecules themselves are moving.
> 
> 
> - The problem with using a high density material is getting the sound to get into it in the first place. If it is too dense then too much of the sound will be reflected from the front surface and it won't matter how good an absorber it is.
> 
> 
> I say speculation above because I am still in the process of digesting all the information in this thread myself.
> 
> 
> Brent



Correct, Brent! Higher density means higher flow resistance. The exact relationship depends on the material, in ways that we don't fully understand but can at least measure. For a material of a certain flow resistance, there is an optimum absorption thickness for a given frequency. Much thinner, and the porous absorber is not very effective due to wavelength size, as you already know. Much thicker, and the higher flow resistance (higher acoustical impedance) kicks in and prevents some of the wave from getting into the material to be absorbed.


Regards,

Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Correct, Brent! Higher density means higher flow resistance.



Eureka! That's right, we are talking about moving air molecules! Slow the air molecules, attenuate the frequency.


----------



## Caspyr

Wow, really long thread, and I am trying to get through it all.


My room is 22' long and 18.5 wide, but it isn't square. At the 16' mark the rest of the rear is "half a hexagon", like the top half of a stop sign.


What do you do for a room like that. I have 1" channels built in to all the moulding and around the windows to put in panels or whatever, just have no clue how/what I need.


I think it sounds way good now, what will putting the extra money in do for me.


If it matters, I have Martin Logan SL3's up front and Aerius in the rear.


----------



## Stima

My room is identically shaped but slightly smaller.


For my room, I built a 10" riser in the "back\\square" portion of the room and built my screen (with curtians) in front of the half hexagon making the room appear square. This allowed me to put all my front speakers behind the screen. My sound stage is nearly perfect as I have all speakers at the exact same height at midpoint of the screen.


Acoustically I treated the room as follows:


Entire hexagon area and side walls up to the first row of seats: fully lined with 1" OC703. I lined the ceiling behind the screen as well.


Side walls after first row of seats and rear wall: 50% coverage with 1" OC703. The other 50% areas I used cotton batting to fill in the 1" space. I SERIOUSLY regret this however as the batting pushes against the GOM covering it producing a "bubble" effect. Even stretching the material as best I could did not remove this bubble and some minors puckers.


Bass traps: I put "super chunk" style traps (made of OC703) in the ceiling to wall corners behind the screen. I also built a very large, free standing frame to hold 12, OC705 sheets. (2 sections at 6" thick each...held 4" off the wall). The back piece of 705 has FSK facing the front wall.


I also put a 8' long "super chuck" style trap behind the rear row along the back wall\\ riser floor corner.


All in all, I would have liked to have a little more bass trapping in the back corners (especially the tri-corners), but I just didn't like how they looked. The bass response is actually nearly perfect in the back row. There is a slight room mode in the front row giving a hump around 100hz. Its not horrible, and I may look into controlling it with a BFD.


I can share picks of how I did all the acoustic stuff if you wish...just let me know.


Hope this helps.


----------



## pepar




> Quote:
> Originally Posted by *Caspyr* /forum/post/0
> 
> 
> Wow, really long thread, and I am trying to get through it all.
> 
> 
> My room is 22' long and 18.5 wide, but it isn't square. At the 16' mark the rest of the rear is "half a hexagon", like the top half of a stop sign.
> 
> 
> What do you do for a room like that. I have 1" channels built in to all the moulding and around the windows to put in panels or whatever, just have no clue how/what I need.
> 
> 
> I think it sounds way good now, what will putting the extra money in do for me.
> 
> 
> If it matters, I have Martin Logan SL3's up front and Aerius in the rear.



Hopefully, you'll get the brians, the terrys and the ethans to comment, but from my limited knowledge I'd say that there's no way to "predict" how it will sound, and therefore know what treatments to install. All of the spreadsheets and calcs I've seen are for rectangles and - horrors! - squares. More sophisticated acoustical modeling is no doubt available, but not as a free or relatively free download. The best recommendation may be for you to consult/hire a professional to analyze the room. (This advice is from someone who's a devout DIY'er.)


As for the windows, I will go out on a limb and say that the more complete your light control is, the better it will be for the video part of the theater.


----------



## Caspyr




> Quote:
> I can share picks of how I did all the acoustic stuff if you wish...just let me know.



I would love to see any pics. The hex part of my room is the back, two Berk's on a platform in the center of it. I would have to totally rebuild to put the screen back there, and I think losing that extra 5 feet would make th room to small for my 123" screen.



> Quote:
> As for the windows, I will go out on a limb and say that the more complete your light control is, the better it will be for the video part of the theater.



There are five total windows, double wide on the side walls, and singles on each of the "hex" walls, all completley light controlled. Black fabric covered panels that fit fit snugly into the window frames. It's wired for curtains, but I like the look of the panels and they work great.


Light control is "perfect" right now, as a flat black room, you are blind in the room if the lights are out and the projector isn't on.


----------



## Ethan Winer

Caspyr,


> What do you do for a room like that.


----------



## Caspyr




> Quote:
> You'd place bass traps in the corner sections as usual.



Either corner in front would be tough to do anything. Looking at the screen the left side is the entry. The door is about 2 ft back from the screen edge. The other side is the audio cabinet doors.


----------



## pepar




> Quote:
> Originally Posted by *Caspyr* /forum/post/0
> 
> 
> Light control is "perfect" right now, as a flat black room, you are blind in the room if the lights are out and the projector isn't on.



I'd say you've got that taken care of.


----------



## Ethan Winer

Caspyr,


> Either corner in front would be tough to do anything.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Caspyr,
> 
> 
> > Either corner in front would be tough to do anything.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I *think* he was referring to "corner" as in "Go sit in the corner." Gravity being what it it, it tends to limit the number of corners one can actually sit in.



Huh? Here's what I read:


"You'd place bass traps in the corner sections as usual."


"Either corner in front would be tough to do anything."


What did you read?


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Huh? Here's what I read:
> 
> 
> "You'd place bass traps in the corner sections as usual."
> 
> 
> "Either corner in front would be tough to do anything."
> 
> 
> What did you read?



HEY, look over there!


----------



## Caspyr

What I am trying to say is that at the left of the screen, there is no corner. Currently about 2' behind the sceen on the left side is a curtain that is the entrance. The left side wall heads straight down past the screen, then a curtain, then the hallway to the rec room/bar area.


Plus, I was thinking of "corners" being where walls meet. I was not thinking top corner/bottom corner where the walls meet ceiling/floor. I am a 1k brain, to me a room has 4 corners not 8










That's why I need places like this, gotta love the amount of information you can get from all you guys. Thanks !!


----------



## kiwishred

In the spirit of giving back something to this great thread, here are construction details for my absorbers (ideas borrowed from here and Bob Golds).


I chose to go with an open frame construction for reasons of (a) light weight, (b) open sides for greater total area of fiberglass exposed, & (c) ease of custom-tailoring thickness. For room aesthetics reasons, total thickness was limited to 3. I used a stack of three 1 sheets of 3 pfc rigid fiberglass in each frame. However, the construction method would also easily allow 2 of fiberglass with a 1 gap to wall (or any other desired combination). While the third sheet might not increase acoustic absorption much, it apparently does no harm and only adds a relatively small incremental cost ($3.52).










Top and bottom frames constructed from 3/4*1/2 hemlock and clamped square. Top frame used shoe moulding and mitred corners to provide a rounded front edge. Bottom frame used rectangular molding and butted corner joints.










Nailing and gluing the top and bottom frames together. Pillars are 2 1/8 for 3 1/8 total thickness.










Drilled guide holes for the #17 * 1 wire nails used to tack the mitred top frame pieces onto 3/4" square pillars using a cut-off #18 * 1 nail (an old trick my dad taught me







).










Front views of finished raw frame (left) and completed, covered, frame (right).










Speaker cloth stretched and stapled onto frame following instructions here. Cloth is actually a lot darker than it appears in this photograph. Yellow stuff is the "rigid fiberglass" acoustic absorber.



BOM (per absorber):

- 4' * 2' * 1 Johns Manville 3 pfc rigid fiberglass sheets. Source: E J Bartells, 700 Powell Ave SW, Renton, WA. 425-228-8807. Cost: 3 sheets @ $3.52 = $10.56.

- 3/4 * 1/2 hemlock 1/4 rounded shoe for front frame. Source: Lowes. Cost: 2 8' lengths at $3.36 each = $6.72.

- 3/4 * 1/2 hemlock rectangle (for back frame and 6 mid posts). Source: Lowes. Cost: 2 8' lengths at $3.36 each = $6.72.

- 3/4 * 3/4 hemlock square (for pillars). Source Dunlumber. Cost 2' @ 85 c/foot = $1.70.

- 60 wide black speaker cloth. Source Jo-Ann. Cost: 1 yd @ $6.80/yd = $6.80.

- miscellaneous (nails, glue, sandpaper, etc) $0.50.


Total cost per absorber = $33. This includes some waste as could only buy the molding in 8' lengths.


Total time per absorber (once in production mode & not counting time for glue to dry !) approx 2 - 3 hrs. So, I probably spent less time making them than reading about how to make them plus the multiple trips to various stores buy materials







.



Observations & tips:


- Top and bottom frames were laid out on a sheet of 3/4 MDF to provide a nice flat surface as the glue set. Didn't have any significant problems with warping.


- I mitred the top frames and made them out of shoe moulding to provide a nice rounded appearance. The rounding was hard to actually notice once the black grill cloth was on the frame. Despite this, and the fact that this approach requires twice as many cuts, I still think it was worth the extra effort.


- All cuts were made by hand using a 16 point dovetail saw and mitre box. All lengths were marked using pre-cut wood pieces rather than a tape measure. This really helped speed & consistency.


- Added 1/4 clearance for fiberglass so that total outside dimensions were 49 3/4 * 25 3/4 * 3 1/8.


- Didn't bother painting the wood. The bare frames and the (yellow) fiberglass are not visible through the speaker cloth.


- I was pleased with the way the finished absorbers turns out. Not too obvious that they are DIY. The 3/4" * 1/2" hemlock provided a nice balance between rigidity and weight (although something a bit beefier would be required for frames any larger than these).



Hope the above is useful to other would-be DIY'ers and thanks to other contributors to this thread


Brent


----------



## Felgar

Wow Brent, looks terrific. I think the rounded edges are a great touch. I only have 2 questions:


1) How are you planning on mounting them to the wall?


2) Did your rigid foam have a paper backing like 703 does? If so, what did you do with it?


----------



## kiwishred

Felgar - Thanks for the comments. I guess the edges could also be rounded with a router. Problem is, I don't own one.


This is a works in progress so mounting has not yet been determined







. First thought is to just hang them over a couple of nails that are 5/8" proud of the wall. Nails would fit in gap between upper horizontal cross piece and fiberglass. The heads of the nails would provide a lip to help stop them falling off. However, these things are fairly light (or more accurately, have a high surface area to weight ratio) so I am not all that concerned about what would happen if they fell of the wall. Would be more of a "thud" than a "crash". The alterative would be to make little flat plate hangers, or perhaps use a short length of chain (anything that is an inch or so long and has a couple of holes) that could be screwed into both the frame and wall.


I am yet undecided if I am going to put some sort of cloth backing on the these. Once on the wall, the fiberglass cannot fall out. And the fibers seem fairly well bonded......


The rigid fiberglass I used was "unfaced". 703 is for sure available unfaced as well.


Brent


----------



## PYD

I am just starting planning after months of reading. I have a room 22x22x10. (I know square is not good). Do I need to build 2x4 walls with GG and two layers of sheetrock or will the 12" cement walls keep sound from traveling. This room is under a garage with an 10" slab. Only one entry door and three sides totally underground and one side into the rest of the house. Was thinking I could just put strapping on walls and not sheetrock? Will this work or do I need to frame walls? Thanks


----------



## TAllen01

I am on going to buy 1" Linacoustic to line the lower half of my side and front walls. I finally found it locally. I will have some left over. Can I make panels out of this (stuffing it into frames), instead of buying rigid fiberglas panels (which I am having a heck of a time finding locally)? Just trying to save cost, and to use what I have. Also, how is everyone dealing with with outlets once you mount and cover the Linacoustic? Cut holes in Linacoustic and cloth cover, and then extend the outlets 1" from the drywall? With speaker wires, RCA outs, and electric outlets, I'm not sure it will look right (e.g., nice and flat). Any thoughts on how to deal with this issue?


----------



## texas teacher

Ya'll seem pretty detailed. What's wrong with a little Quietrock sheetrock on the walls and Quietwood on the floors? Seems a lot simpler.


----------



## patrickjherbert

Let me start by saying that it is a little intimidating entering a thread where some of the participants are clearly experts in their field, and are willing to go to great lengths in the pursuit of perfection. I've been plowing through this thread a little at a time over the last couple of months while in the planning stages for the re-do of my basement, and would like to get your opinions on getting the maybe 85-90% of perfection that I think should be realistically and easily achievable in my circumstance.


I'm dealing with a typical tri-level basement, not very large with ceilings that are about 7'6" when finished. This will be a VERY mixed use room - more than a dedicated home theater. In fact, I will probably do more (casual to serious) music listening than movie watching. I'm building a bar at one end and shoe-horning in a 7' pool table next to that. There will be a number of compromises as a result of everything we are attempting to do, but my goal is to achieve the best acoustic response I can, with the greatest range of usability for the room.


This room had been "finished" by the former owner of the house, and I first had to undo pretty much everything they did. So far I've torn down the sheetrock (which never had the seams taped,) reframed most of the walls (which had stud spacing anywhere from 12" to 20" on center as the mood struck,) and redone the electrical (which could have burned down the house.)


At the end of this post is my hand drawn sketch of the room. Sorry, but I haven't had time to work on this project more than 1 1/2 days a week on average, and I didn't want to spend a couple of days trying to figure out how to use SketchUp.


I'm going to put R-13 behind the drywall and in the ceiling, and was going to put 2" OC 703 behind the stage area. OC 703 superchunks in all four corners (above and below the two rear corner speakers.) I know that putting the rear surrounds in the corners is not optimum, but windows, the pool table, and other space considerations make that compromise necessary. Ditto for the side surrounds.


Finally, my thought was to cover the bottom 40 or so of the right side wall and rear wall with fabric we have picked out that is fairly heavy and passes about 50% of the acoustically transparent breath test. Behind the fabric would be 2 OC 703 for a padded wall effect. On the left side of the room there is almost no available space for doing the padded wall thing.


I was thinking that using 2 703 on the side and rear wall instead of the 1 that seems to be more the norm on these forums would make up for the lack of 703 on the left wall. In the end I decided to ask for informed directions before I got too carried away with my assumptions.


Thanks in advance for all the time and information you all share with these groups. Immediately after this post I'll post a panoramic picture of this space as it looked last week, taken from the bottom left corner of the sketch.


----------



## patrickjherbert

Here is a panoramic shot of the carnage so far. This picture was shot

from the back corner of the bar (lower left-hand corner in the diagram.)

That big empty space on the left side will be a 90 gallon saltwater reef tank someday.


The wall studs are not really crooked, that and some "ghostly" tools are from the stitching program I use.

A seven foot (bar size) pool table will be going to the right of the

bar, and a curved leather sectional sofa will be in front of the Plasma, angled slightly towards the upper right-hand corner of the room.


Don't laugh, you should have seen this room a week ago!


----------



## Terry Montlick




> Quote:
> Originally Posted by *texas teacher* /forum/post/0
> 
> Ya'll seem pretty detailed. What's wrong with a little Quietrock sheetrock on the walls and Quietwood on the floors? Seems a lot simpler.



These products are used for sound isolation -- to make your room quiter, and allow less sound to escape to other rooms. They do not improve in-room acoustics, as do absorber panels and other sound treatments. You need *both*. Sorry that it is even more complicated.










Oh, and for sound isolation, you can't just do one part of a room, because sound will happily travel right through the areas you haven't done. So a "little Quietrock sheetrock" becomes "a lot" -- enough for all your wall surfaces and ceiling.


Regards,

Terry


----------



## eugovector

I've put up some pics and diagrams of my project and have several questions about Positioning Acoustic Panels in an Apartment. I could really use some of the brainpower in this thread. Thanks in advance.


Please comment in this thread:
http://www.avsforum.com/avs-vb/showthread.php?t=734181


----------



## TumaraBaap




> Quote:
> Originally Posted by *patrickjherbert* /forum/post/0
> 
> 
> Let me start by saying that it is a little intimidating entering a thread where some of the participants are clearly experts in their field, and are willing to go to great lengths in the pursuit of perfection.



Sometimes I think the thread ought to be unstickied. Many views expressed at the beginning by some of the "experts" have probably evolved considerably. The use of absorption for one is over rated in this thread. (And absorption that defies room symmetry has thankfully never been highly rated.)


Firstly, one is no way NEAR perfection in terms of acoustics if the loudspeaker being used is shoddy. Clearly enthusiasts ought to be demanding better but the infatuation with loudspeakers featuring primitive easily saturated passive crossovers continues. There are indeed very few consumer loudspeakers with the requisite on and off axis flat frequency response.


Once you start with a superb loudspeaker, it's better to optimize reflection and diffusion in the horizontal plane. Early reflections can aid musicality and speech intelligibility. Diffusion affords an enveloping passive surround that complements active surround of multichannel setups. Screw the linacoustic. Any absorption, reflection or diffusion ought to be as broad in bandwidth as possible lest it unbalance the off axis prowess of the loudspeaker being used. Whereas reflections may work laterally, the front and rear reflections are best attenuated or diffused (the latter preferred with adequate distance from diffusor -quadratic residue or prime root- to listening seat). Bass distortion is the worst offender in typical rooms and the ceiling/or wall ceiling corners is a strategic choice for broadband bass traps. The rest of the ceiling can be interspersed with broadband diffusion and absorption. Tortuous calculation of reverberation times is hogwash. With a treated ceiling and furniture, one may already have enough absorption to get away with hardwood floors and area rugs. The Welti/Toole configuration of multiple subs and parametric eq of peaks below 300 Hz should round out amelioration of bass distortion not fixed by broadband bass traps and drywall flex.


Most of this is a far cry from the linacoustic loving advice you'll find in this thread. Balance out whatever advice you typically would get here with what Richard Bird, Russ Berger, John Storyk, or Floyd Toole would advocate (even though they're not always right). Google away.

Tumara Baap


----------



## Ethan Winer

Tumara,


That's a great post and I agree with almost everything you said. I too don't understand why this was even made a sticky in the first place. It's way too much for anyone to digest, it's full of contradictory and often wrong opinions, and the signal to noise ratio is low.


> enthusiasts ought to be demanding better but the infatuation with loudspeakers featuring primitive easily saturated passive crossovers continues.


----------



## ciotime

Are stages and risers in HT rooms bolted/nailed/screwed to the floor? I would think that they're not so as to decouple them from the floor. But in so doing arent the stage and riser susceptible to movement considering that its not attached to anything? Also is it ok if I only put sand only for the stage where the speakers and sub will be and insulation inside the risers?


----------



## pepar




> Quote:
> Originally Posted by *ciotime* /forum/post/0
> 
> 
> Are stages and risers in HT rooms bolted/nailed/screwed to the floor? I would think that they're not so as to decouple them from the floor. But in so doing arent the stage and riser susceptible to movement considering that its not attached to anything? Also is it ok if I only put sand only for the stage where the speakers and sub will be and insulation inside the risers?



FWIW, my riser is not attached to te floor, but it is of sufficient weight that it might as well be. And my LZBoys, feet cradled in "channels," are held only by gravity as well. I constricted the outer frame of the riser from 2 x 12's and the cross members from 2 x 10's effectively suspending the top. I had done this thinking thAt I might add a bass transducer at some point in the future, but it resonates on it's own at around 25Hz so nicely that no active driver is required. Check my link and navigate to the appropriate page to see how I did it.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> 
> > Early reflections can aid musicality and speech intelligibility.
> Tortuous calculation of reverberation times is hogwash.


----------



## Ethan Winer

pepar,


I think your "I came, saw, got drunk" sig is having an effect.







I can't tell which side you're taking here:


> I've experienced the exacty opposite with absorbers at the first reflection points - ALL first reflection points - making a HUGE difference in the intelligibility of music and speech.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> pepar,
> 
> 
> I think your "I came, saw, got drunk" sig is having an effect.
> 
> 
> 
> 
> 
> 
> 
> I can't tell which side you're taking here:














> Quote:
> > I've experienced the exacty opposite with absorbers at the first reflection points - ALL first reflection points - making a HUGE difference in the intelligibility of music and speech.
> am I now to believe that decay is not important because I don't have any reverb?


----------



## KERMIE

How do you handle First Reflection points for Surrounds and rear (Dipole). Are they not suppose to follow the wall a little?


Or should you address these with some treatment?


Thank you


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> How do you handle First Reflection points for Surrounds and rear (Dipole). Are they not suppose to follow the wall a little?
> 
> 
> Or should you address these with some treatment?
> 
> 
> Thank you



I think dipole surrounds are _supposed_ to reflect from the surrounding surfaces to develop the soundfields.


----------



## KERMIE

So if I have a 13 foot wide room and 24 " face base traps in each of the back corners (Floor to Ceiling) it will leave me about 10 feet for a flat back wall. If the rear speakers are on the back wall about 5-6 feet apart will there be enough room between the outside driver of the dipoles shooting towards the base trap. (approx 2 feet from base trap)


thank for the help.


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> So if I have a 13 foot wide room and 24 " face base traps in each of the back corners (Floor to Ceiling) it will leave me about 10 feet for a flat back wall. If the rear speakers are on the back wall about 5-6 feet apart will there be enough room between the outside driver of the dipoles shooting towards the base trap. (approx 2 feet from base trap)
> 
> 
> thank for the help.



I like dipole surrounds in a 5.1 system to be on the sides for movies. If I listened more to music I'd rather have monopole (or tripole) speakers in the back.


I'm pretty sure I didn't (directly) answer your question. How far from the rear wall is you back row of seats?


----------



## TumaraBaap

I consider Ethan an authority, and his views are duly noted. In any case, I recommend anyone on an acoustics forum to read Toole's paper for themselves: Loudspeakers and Rooms for Sound Reproduction - A Scientific Review, J. Audio Eng. Soc., Vol.54, No.6, June 2006. This paper is excellent and will prove to be seminal for years to come.


Toole does not upend the conventional wisdom for using side wall absorption; to lock an image in place. If anything, he and Olive have demonstrated in earlier studies how varying the amplitude and delay of lateral reflections affects our perception of spaciousness and image shifting and spreading. He further allows room for standards of reflection control to be developed for multichannel configurations. That said, the paper is unequivocal in enthusing about early lateral reflections.


"Persuasive evidence points to several beneficial and few negative effects of early reflections" ... "Multiple reflections improve the audibility of timbral cues from resonances in the structure of musical and vocal sounds" ... "Early reflections improve speech intelligibility" ... "Early lateral reflections increase our preference for the sound of music and speech. Individual reflections in small rooms may be too low in level to have the optimum effect, thus providing opportunities for multichannel sound"


A notable caveat: Toole insists that for the precedence effect (whereby the brain correctly localizes a sound source in the wake of strong early reflections) to work, the tonality of the direct and reflected sounds should be very close. "If the spectrum of a reflection is different from that of the direct sound, the probability that it will be heard as a separate spatial event is increased - not a good thing." In that case, for most audiophiles with their allegedly cool loudspeakers, the drawl of an Alabama Sheriff upon meeting up with a wrongdoer ought to apply; "Tell you what son, yo ass is s*** outa luck!" They are better off sticking with OC 703 and calling it a day. I might point out that Toole's findings seems to be in line with the observations of those who have designed (or reviewed) highly accurate systems with an excellent polar response, such as teams behind DEQX/ NHT Xd, Seigfried Linkwitz and his Orion, and above all my guru Peter Aczel.


Frankly, I'm not technically inclined enough to argue the merits or otherwise of early reflections in small rooms. I just wanted to give fellow enthusiasts a glimpse of what's in the paper and strongly urge them to read it themselves. As always, I'm in utter awe of Toole's scientific flair. He ruffles many an arbitrary belief, and boy isn't that a lot of fun.










Tumara Baap


----------



## KERMIE

Pepar, my rear speakers will be about 6 feet from the back of the seating area about 1.5 -2 feet above the ears. The same height as the sides.


So if you can picture the back wall like I tried to describe firing about 2 feet from a corner base trap on each of the outside drivers. and about 6 feet apart (inside driver) from each other mounted on the back wall.


I will probably not do anything with that drywall that the speakers will be mounted two but just had some concerns on the outside drivers and the corner base trap.


TumaraBaap, I will look into that......thanks


----------



## Schwingding

"Flabbergasted" is what I'd like to title this post.


This is probably my first post in this thread/forum. I'm still in reading and learning mode, but have digested enough info that I'm ready to tackle accoustic treatments in my new basement/HT room.


I've spent the last 3 days calling every local (Baltimore) insulation provider listed, and most of the "Home Theater" installers, too, searching for a source of OC703/705. What have I succeeded in? NOTHING. What have I learned? I have learned that there is a shocking lack of knowledge and experience in room treatments. A good 1/2 of the "HT installers" I spoke to don't do anything with regards to room treatments. A salesmen at the local Tweeter was completely in the dark, and most of the insulation supply houses don't carry it or want to sell me something completely unsuitable for the application. They all think I want to "soundproof" a room. In short, you guys are making me look like I'm the one who's nuts!










I could buy OC703, oh sure, if I wanted to order a truckload. I need about 30 sheets. So, until I find a suitable local supply, (help anyone? please?) I've had to order it off of the internet, which cannot be anywhere near cost effective.


Flabbergasted. But I'm sure its worth it. You should hear my new 20'x25' room with its bare walls, YIKES! Eww!


Thanks for letting me get that out there. I feel much better.


----------



## MarkMac




> Quote:
> Originally Posted by *Schwingding* /forum/post/0
> 
> 
> I could buy OC703, oh sure, if I wanted to order a truckload. I need about 30 sheets. So, until I find a suitable local supply, (help anyone? please?) I've had to order it off of the internet, which cannot be anywhere near cost effective.



Schwingding-

I had similar issues until I found SPI. I'm not sure what the closest location is to you (Lancaster, PA?), but I was able to get boxes (24sheets) of 2x4 OC703 1" for ~$80. 45cents/sq.ft. was better than any other price I found.


You may want to look into that:
http://www.spi-co.com/servicecenterdirectory.cfm


----------



## Schwingding




> Quote:
> Originally Posted by *MarkMac* /forum/post/0
> 
> 
> Schwingding-
> 
> I had similar issues until I found SPI. I'm not sure what the closest location is to you (Lancaster, PA?), but I was able to get boxes (24sheets) of 2x4 OC703 1" for ~$80. 45cents/sq.ft. was better than any other price I found.
> 
> 
> You may want to look into that:
> http://www.spi-co.com/servicecenterdirectory.cfm



That link should be in a master list of references! One call to the Lancaster office and I was speaking with Rick Remington, who proved extremely knowledgable, friendly, and willing to help out on a small homeowner sized requirement. You just made my day, thank you!


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> Pepar, my rear speakers will be about 6 feet from the back of the seating area about 1.5 -2 feet above the ears. The same height as the sides.



Sooo, this is a 7.1 system?


----------



## Felgar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> A notable caveat: Toole insists that for the precedence effect (whereby the brain correctly localizes a sound source in the wake of strong early reflections) to work, the tonality of the direct and reflected sounds should be very close. "If the spectrum of a reflection is different from that of the direct sound, the probability that it will be heard as a separate spatial event is increased - not a good thing." In that case, for most audiophiles with their allegedly cool loudspeakers, the drawl of an Alabama Sheriff upon meeting up with a wrongdoer ought to apply; "Tell you what son, yo ass is s*** outa luck!" They are better off sticking with OC 703 and calling it a day.



It seems ludricrous to me to think that for the sound reflected off a sheet of drywall, the wall itself would have little to no effect on the tonal characteristics of the sound. The wall is not perfectly smooth and will also vibrate, thus adding it's own sound to the reflected sound. Even differing wall constructions will yield different behaviour so I don't see how the reflected sound could be considered close to accurate. The ceiling is probably even worse, suffering from (typically) less accurate vertical off-axis dispersion of the speaker and a surface that's not nearly as smooth with a typical stippled construction.


----------



## pepar




> Quote:
> Originally Posted by *Schwingding* /forum/post/0
> 
> 
> That link should be in a master list of references! One call to the Lancaster office and I was speaking with Rick Remington, who proved extremely knowledgable, friendly, and willing to help out on a small homeowner sized requirement. You just made my day, thank you!



I, too, bought my OC703 from Rick. Did you know he has a musical and recording studio background? A few others in the office as well.


----------



## KERMIE

Yes it is 7.1,


so basically I would have 1 side of each of the 4 dipole surrounds firing towards a Corner Base trap. I see this a lot on some of these theaters but what effect does that have on Dipole for surrounds.


----------



## eugovector




> Quote:
> Originally Posted by *Schwingding* /forum/post/0
> 
> 
> That link should be in a master list of references! One call to the Lancaster office and I was speaking with Rick Remington, who proved extremely knowledgable, friendly, and willing to help out on a small homeowner sized requirement. You just made my day, thank you!



So how much did everything cost, does he ship?


I went with ejdavis.com, based in CT, who shipped 2" unfaced 703 in cartons of 6. I bought 12 2x4 sheets @ 77 cents/sqft. Shipped in 2 boxes, my total was $118.94.


ejdavis was a much better price than I found anywhere else, and though I can't afford any more right now, I'll probably be building some more panels in the future. So far, simply putting a single panel at the first refelction points on my left and right walls produced a noticably more clarity in center channel dialogue. I've started recommending this to everyone,and by far the most complicated part of the whole process is finding 703 at a decent price.


----------



## Ethan Winer

pepar,


> Does not a room with "decay issues" have a "reverb" problem?


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> Yes it is 7.1,
> 
> 
> so basically I would have 1 side of each of the 4 dipole surrounds firing towards a Corner Base trap. I see this a lot on some of these theaters but what effect does that have on Dipole for surrounds.



OK, my preference is to use monopoles for the rears in a 7.1. If your's are not adjustable, I would suggest moving them a wee bit closer together. As there are no discrete rear channels (yet) you will not be losing any separation. And you'll probably generate a more enveloping rear soundfield by hetting them away from your traps.


Just my $.01, $.02 or $.03.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> pepar,
> 
> 
> > Does not a room with "decay issues" have a "reverb" problem?


----------



## TumaraBaap




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> It seems ludricrous to me to think that for the sound reflected off a sheet of drywall, the wall itself would have little to no effect on the tonal characteristics of the sound. The wall is not perfectly smooth and will also vibrate, thus adding it's own sound to the reflected sound. Even differing wall constructions will yield different behaviour so I don't see how the reflected sound could be considered close to accurate. The ceiling is probably even worse, suffering from (typically) less accurate vertical off-axis dispersion of the speaker and a surface that's not nearly as smooth with a typical stippled construction.



Those reflections apply to frequencies above the schroeder/transition frequency where the drywall would be more or less uniformly reflective. Below the transition frequency, drywall flex actually aids modal issues. Any texturing of the typical wall would only affect frequencies way above 20KHz. Rest assured, there is absolutely no need to be looking into a smooth as glass concrete wall. As for vertical off axis problems, you're on top of things. Hence the operative word "lateral" when speaking of the beneficial early reflection in question.

Tumara Baap


----------



## Felgar

Well, thanks for sharing Tumara. If nothing else I'll be sure to keep an open mind and A/B with and without treatments on my first reflection points.


----------



## pepar




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> Well, thanks for sharing Tumara. If nothing else I'll be sure to keep an open mind and A/B with and without treatments on my first reflection points.



The first absorber - 2" OC Selectsound Black - I placed at a first reflection point was the REAR wall, a surface that sometimes gets overlooked by us layman. The difference was ASTONISHING - improvements in clarity, main/surround integration and somewhat tightened bottom. The next surfaces I treated were left and right front walls. This produced an incremental improvement in clarity and main/surround integration. The final surface treated was the front ceiling. This made a larger improvement in the aforementioned areas than the side wall treatment, but not as great as the rear wall did.


Just my $.01, $.02 or $.03.


----------



## KERMIE

So on my back wall, which will be about 14-15 feet away from my Front speakers, should I use some sort of diffusion panels? if I keep it away from my rears (like above or below)?


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> So on my back wall, which will be about 14-15 feet away from my Front speakers, should I use some sort of diffusion panels? if I keep it away from my rears (like above or below)?



I used absorption. Others recommend diffusion, and I might give that a try myself - just to see the effect. If you used diffusion, you would (probably) not need to worry about it's proximity to your surrounds.


----------



## Ron Jones

For item (a) I don't understand what is being implied by the "polyester batting above". Where and how is the polyester batting used?


Ron Jones


----------



## Felgar




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> The first absorber - 2" OC Selectsound Black - I placed at a first reflection point was the REAR wall, a surface that sometimes gets overlooked by us layman. The difference was ASTONISHING - improvements in clarity, main/surround integration and somewhat tightened bottom. The next surfaces I treated were left and right front walls. This produced an incremental improvement in clarity and main/surround integration. The final surface treated was the front ceiling. This made a larger improvement in the aforementioned areas than the side wall treatment, but not as great as the rear wall did.



Wow, thanks for the tip. I was thinking to target the sides first and go from there but this is interesting food for thought. In my case the main LP will be a home theatre recliner at front-center, and behind that will be a leather sofa on a 12" riser. I expect the reflection point to be the lower portion of the back of the sofa. So hopefully the sofa behaves better than a wall in terms of absorbtion and reflection. It will probably reflect high frequencies a fair amount; I guess I'll play around to see if buying a cloth sofa would make a substantial difference in SQ...


----------



## eugovector




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> Wow, thanks for the tip. I was thinking to target the sides first and go from there but this is interesting food for thought. In my case the main LP will be a home theatre recliner at front-center, and behind that will be a leather sofa on a 12" riser. I expect the reflection point to be the lower portion of the back of the sofa. So hopefully the sofa behaves better than a wall in terms of absorbtion and reflection. It will probably reflect high frequencies a fair amount; I guess I'll play around to see if buying a cloth sofa would make a substantial difference in SQ...



I had the same results, but did the sides first. Based on my temp placement so far, I'd say you should do sides, back, and ceiling.


Instead of buying a cloth sofa, how about just putting a think blanket over the back of the leather one?


----------



## chillinintheoc

Im getting ready to put the 1" Linacoustic RC on my walls....is there a front and back to this stuff?

What part do I put agents the wall?

And what is the best thing to use for your 1" Furring strips?


Thanks

Chillinintheoc


----------



## bpape

Ron.


The batting is used on the upper half of the walls to fill in behind the GOM to the same level as the Linacoustic below. If you don't want the extra HF absorbtion you can use something inert like styrofoam that will not absorb anything but will provide a more solid backing.


Chillin,


Use the side with the coating on it out toward the room. You'll have to rip the 1" strips yourself - or spend a lot of money buying craft lumber.


Bryan


----------



## Stima




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Ron.
> 
> 
> The batting is used on the upper half of the walls to fill in behind the GOM to the same level as the Linacoustic below. If you don't want the extra HF absorption you can use something inert like Styrofoam that will not absorb anything but will provide a more solid backing.



Damn it...had a nice thought out response as to why I hate my batting...and then I hit the wrong button and it all disappeared.










So, long story short....I hate my batting above my OC701 so much so I actually considered tearing down all my GOM and wood work to replace the batting with wood, drywall or even Styrofoam as Bryan suggests. I found it impossible to get the batting to lay perfectly smooth as it does over the fiberglass. The fiberglass fibers hold the GOM nice and smooth while the batting causes it to "poof" out.


Anyway, do what you want...but the very very small amount of high freq. absorption afforded by the batting is FAR outweighed by the PITA poofy factor. (IMHO)


----------



## Stima




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> 
> Use the side with the coating on it out toward the room. You'll have to rip the 1" strips yourself - or spend a lot of money buying craft lumber.
> 
> 
> Bryan




I went a different route than the above suggestions:


I looked around my local Home Depot and of course didn't find any wood that was perfect for 1" tall firring strips. However, I DID find some .75" tall pine and some .25" tall pine that stacked up to be the perfect height. Now, while I *could* have bought the exact same length for each material...I went the even MORE economical route of cutting the .25" stripes into 2" long "spacers". I simply nailed\\screwed the .75" strips to the wall every foot or so with a spacer between it and the wall. I found I had to pre-drill holes in the spacers to keep them from cracking, but it worked very well. I pretty much only air-nailed\\screwed at the wall studs. If I had a piece of firring that didn't line up on a stud, I used cheap drywall hangers (the plastic butterfly things that expand when you screw into them). This took a little extra time to put in the hangers, but I probably saved 50$ in wood. In either case, I would have had to use drywall hangers for some short firring pieces around outlets and at the riser steps.


To get a better idea here are a few pics of my room. Every where you see brown trim, there is firring strips behind the trim. This allowed my to make a pattern with my GOM and NOT have ANY visible seams. The GOM on each wall is a single continuous piece. FYI: I used outlet covers to hide the staples around the outlets along with small pieces of window molding under my soffits to hide staples and generic floor board molding at the floor. (It was all generic pine I stained.)


Front:










Back:


----------



## pepar

Stima, do you not find you get a lot of light reflecting off of the light surfaces, especially the ceiling, that washes out the projected image on the screen?


----------



## Stima

I do see some light reflecting off the ceiling and walls, but it does not deter the picture any that I can see.


I will take a picture of a paused movie with a wide angle lens and post it back.


edit: added pictures and modified above sentence regarding reflected light.


Didn't level tripod well, but you'll get the idea. Also, chromatic distortion by unicorns head is only seen on camera, not on screen.










Sony DSC-H5 F3.5, 1/2 sec, ISO-125










Sony DSC-H5 F3.5 1/6 sec, ISO-125

Zoomed to show lack of "wash out"


----------



## TAllen01

I agree with some of the posts from last week. We need a sticky for "where to buy" DIY materials for acoustic treatments. I, like many others, called high and low and spent hours drvingin around trying to find OC 703 or Johns Manville stuff at the Do It Best stores, HD, Lowes, etc. I finally found it by going to the spi website after reading one thread from someone building a theater in my neck of the woods. Once I found them, I made one call and went to pick up as much as I needed. It was all in-stock, 15 miles away, but SOOO hard to find them. I ended up getting a 1.5" thick, Johns-Mansville equivalent to OC 703 for about .80 per square foot near Cincinnati.


----------



## eugovector




> Quote:
> Originally Posted by *TAllen01* /forum/post/0
> 
> 
> I agree with some of the posts from last week. We need a sticky for "where to buy" DIY materials for acoustic treatments.




There's one here: Ethan's Forum


----------



## pepar




> Quote:
> Originally Posted by *TAllen01* /forum/post/0
> 
> 
> I agree with some of the posts from last week. We need a sticky for "where to buy" DIY materials for acoustic treatments. I, like many others, called high and low and spent hours drvingin around trying to find OC 703 or Johns Manville stuff at the Do It Best stores, HD, Lowes, etc. I finally found it by going to the spi website after reading one thread from someone building a theater in my neck of the woods. Once I found them, I made one call and went to pick up as much as I needed. It was all in-stock, 15 miles away, but SOOO hard to find them. I ended up getting a 1.5" thick, Johns-Mansville equivalent to OC 703 for about .80 per square foot near Cincinnati.



These materials can be purchased most economically at an HVAC (Heating Ventilation and Air Conditioning) supplier, but you must find a smaller one unless you need a lot of material or find one who'll accomodate you. I purchased two rolls of J-M Linacoustic at a distributor in the Philly area and three packs of four 4x8 sheets of OC SelectSound Black at a distributor close to MD. When I wanted to buy OC 703, I again priced it at the Balto place, but also found SPI . Coincidentally, their headquarters is 20 miles from my home. Their price was SO much better than the Balto one that I was insulted! The link is to their service center directory and shows locations all over the country with the highest concentration east of the Mississippi. They carry many brands, have favorable pricing and are the best resource I've run across for acoustical materials.


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> I do see some light reflecting off the ceiling and walls, but it does not deter the picture any that I can see.



I guess it's a matter of preference - and how easily one is distracted. Personally, the light reflecting off the ceiling and the side walls would distract me too much. I prefer flat black so there is NO light coming at me from anywhere other than the screen.


----------



## Stima

The light reflection would probably be more noticeable if the viewing distance to screen diag ratio wasn't so close to 1. (10' wide screen with seating at 12" and 16")







The picture is just so huge, my eyes just don't ever notice the extra light on the walls and ceiling.


----------



## eugovector




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> The light reflection would probably be more noticeable if the viewing distance to screen diag ratio wasn't so close to 1. (10' wide screen with seating at 12" and 16")
> 
> 
> 
> 
> 
> 
> 
> The picture is just so huge, my eyes just don't ever notice the extra light on the walls and ceiling.



I'm assuming you meant 12' and 16'. What's your source, don' t you find that too large/close for viewing?


Watching DVDs at a little less than 2 times the screen diagonal, I start to see some softness in the picture.


----------



## Stima




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> I'm assuming you meant 12' and 16'. What's your source, don' t you find that too large/close for viewing?
> 
> 
> Watching DVDs at a little less than 2 times the screen diagonal, I start to see some softness in the picture.




Yeah, 12' and 16'. I currently am running a InFocus SP4805 with a Panamorph Horizontal Expansion Lens to achieve 2.35:1. Source material is DVD and an old HD OTA receiver for Monday Night Football. I have a media server with DVD rips just itching to be used, but I don't have the cash to purchase a Media Extender that can handle ISO's.


Once I save some more pennies, the FIRST thing I will do is replace the source, projector and lens. I decided to first focus my money on the building of the room and it's audio properties. I can easily upgrade a projector...redoing acoustical treatments on the other hand ain't so easy.


BTW, one of the VERY FEW benefits of poor eyesight is the ability to have a bigger picture and not be able to tell it is soft or pixelated. I have 20/30 and 20/40 vision due to a degenerative eye disease.










Now my brother-in-law who has better than 20/20 can see the pixels at 12' but not 16' where I can only see them at a couple feet.


----------



## eugovector




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> Yeah, 12' and 16'.
> 
> 
> One of the VERY FEW benefits of poor eyesight is the ability to have a bigger picture and not be able to tell it is soft or pixelated.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> My brother-in-law who has better than 20/20 can see the pixels at 12' but not 16' where I can only see them at a couple feet.



My mom always used to say that sitting to close to the television would give me bad eyesight. I guess with your experience to back that up, I'd better scoot back a couple feet


----------



## Stima




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> My mom always used to say that sitting to close to the television would give me bad eyesight. I guess with your experience to back that up, I'd better scoot back a couple feet




sorry for the edit while you were replying.


Yeah, my problem wasn't sitting to close...rather genetics. My twin brother has also been diagnosied. Sucks for us


----------



## kjohn

I am still trying to under stand about treating the rear wall my room is appox. 13'.5" x 8' x 26' should I put a panel on the rear wall.


----------



## eugovector




> Quote:
> Originally Posted by *kjohn* /forum/post/0
> 
> 
> I am still trying to under stand about treating the rear wall my room is appox. 13'.5" x 8' x 26' should I put a panel on the rear wall.



I'm obviously far from an expert, but in my limited experience, I found benefits in treating all first relection points (left, right, front, back, ceiling, floor) for both music and movies.


I'd say yes, at least at 1st reflection points.


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> I'm obviously far from an expert, but in my limited experience, I found benefits in treating all first relection points (left, right, front, back, ceiling, floor) for both music and movies.
> 
> 
> I'd say yes, at least at 1st reflection points.



Treating my back wall made a bigger difference than doing the ceiling or left/right front walls.


----------



## myfipie

Treating the back wall is going to help with nulls and peaks that you would get off the back wall. Treating the side walls is going to help with imaging of the speakers. So yes you do want to treat the back wall and the side walls. For the back wall it might be best to go with a 4" panel spaced off the wall 4". For the side walls a 2 inch panel should work fine.


Glenn


----------



## ciotime

When you say treat the back wall do you mean the entire back wall? Coz on a 7.1 setup Ive read a lot of posts' that say to treat only the middle part of the back wall...ie divide the back wall into 3 parts and leave the right/left back wall reflective.


----------



## pepar




> Quote:
> Originally Posted by *ciotime* /forum/post/0
> 
> 
> When you say treat the back wall do you mean the entire back wall? Coz on a 7.1 setup Ive read a lot of posts' that say to treat only the middle part of the back wall...ie divide the back wall into 3 parts and leave the right/left back wall reflective.



That's good thinking. The rear surrounds, especially if dipole, need reflective surfaces in order to create enveloping soundfields. Determining where *to* treat can be done with the classic "mirror method." I've never used a mirror, but applied the concept by eyeballing. You might be able to visualize it easier if you think of bank shots on a pool table. Angle of incidence = angle of reflection. I've seen some recommending DIFFUSION on the rear wall instead of absorption. With that, one does not need to be concerned about deadening too much rear wall and negatively impacting rear surrounds.


----------



## fredpamm

Guys I need a little help to understand.


Currently I am building out my basement part of which is a home theater. I am in the drywall stage.


I have a room that is 22'6" by 15'3" with two 45 degree angled walls next to the screen (part of foundation).


Technology includes Yamaha 2600, Panny ae900, Dalite da-snap cinema vision 133 diagonal, klipsch rf5, rs52, rc52 rw12d home theatre, oppo 971 dvd player


I have single walls next to the foundation and double decoupled walls on the sides and back of the HT. The cavities are full of insulation walls and ceiling.


All of this I learned on this web site (thanks so much)


Then I started to read this thread about acoustical treatments.


There are so many opinions that I am not sure what's right or wrong.


My eyes glaze over and I am confused....


Can anyone simply break down for me what is needed in my little corner of the world? I have attached somewhat of a drawing of my theater....


Thanks in advance...


----------



## BasementBob

myfipie


> Quote:
> Treating the back wall is going to help with nulls and peaks that you would get off the back wall.



True.


But that's a little like saying the drug digoxin can reduce the ventricular rate of the heart. That is also true, but that doesn't mean that we want to take digoxin all the time.


If the room is large enough and far enough behind the listeners, treating the back wall with absorption might not help at all. In this case the room is 26' long -- which seems to fall into that 'ask more questions' category because the wall is possibly more than 11' behind the listener.


Absorption just isn't something you do. Absorption is a treatment. I'm a big proponent of: Diagnose/describe the problem that needs solving, then treat it.


e.g. Absorption on the rear wall can affect Haas, and/or it can treat a mode, etc. Although the front wall might be better than the rear because the same treatment can also deal with SBIR, and still maintain ambiance. Absorption anywhere can affect RT60, envelopment, as well as the speaker watts required to fill room.


(Side wall reflection taming seems to be good by hugely far most of the time in home theatre. Or to put it another way I'd have to work fairly hard to dream up an example of a in-the-home-theatre where it wasn't the case. Interestingly enough, my living room has a reflection free zone due to the drywall geometry that falls into this category, but it's rare and odd, and unfortunately for me will suffer from other less than optimal problems)


----------



## myfipie




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> myfipie
> 
> True.
> 
> 
> But that's a little like saying the drug digoxin can reduce the ventricular rate of the heart. That is also true, but that doesn't mean that we want to take digoxin all the time.
> 
> 
> If the room is large enough and far enough behind the listeners, treating the back wall with absorption might not help at all. In this case the room is 26' long -- which seems to fall into that 'ask more questions' category because the wall is possibly more than 11' behind the listener.
> 
> 
> Absorption just isn't something you do. Absorption is a treatment. I'm a big proponent of: Diagnose/describe the problem that needs solving, then treat it.
> 
> 
> e.g. Absorption on the rear wall can affect Haas, and/or it can treat a mode, etc. Although the front wall might be better than the rear because the same treatment can also deal with SBIR, and still maintain ambiance. Absorption anywhere can affect RT60, envelopment, as well as the speaker watts required to fill room.
> 
> 
> (Side wall reflection taming seems to be good by hugely far most of the time in home theatre. Or to put it another way I'd have to work fairly hard to dream up an example of a in-the-home-theatre where it wasn't the case. Interestingly enough, my living room has a reflection free zone due to the drywall geometry that falls into this category, but it's rare and odd, and unfortunately for me will suffer from other less than optimal problems)



Well said and I would agree. There really is not a "one size" fits all in any of this stuff. We just got back from treating 3 rooms at the RMAF out in denver and all the rooms where the same size. But because of the different speakers we did have to tweak somethings a little different. So it is not only the room but the kind of speakers will matter also.


Glenn


----------



## Ethan Winer

Fred,


> Can anyone simply break down for me what is needed in my little corner of the world?


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> 
> * Broadband bass traps (absorption)
> 
> 
> * Mid/high frequency absorption
> 
> 
> * Some additional amount of mid/high absorption
> 
> 
> * with seating right up against the rear wall you'll want additional broadband absorption



Has diffusion fallen out of favor?


----------



## fredpamm

Thanks Ethan.


So it sounds to me like some of the OC703/GOM installations that I have seen would handle the angled corners and on the side and back walls. Then put bass traps in the corners...


The floor will be carpet and there is a 12" riser filled with insulation in the back of the room. That should help some, right?


----------



## Stima




> Quote:
> Originally Posted by *fredpamm* /forum/post/0
> 
> 
> Thanks Ethan.
> 
> 
> So it sounds to me like some of the OC703/GOM installations that I have seen would handle the angled corners and on the side and back walls. Then put bass traps in the corners...
> 
> 
> The floor will be carpet and there is a 12" riser filled with insulation in the back of the room. That should help some, right?




For the riser to be useful as a bass trap, it would need to be tuned through the use of a port (think sub woofer port). Just thinking about it in the simplest of ways...having a solid riser in back will do nothing to help treat bass since the bass can't travel well through the solid mass walls and floor to be properly attenuated. So I would have to say the riser stuffed with insulation will do very little to help the room response.


As far as 703 and GOM. Some would say the front wall needs to be as dead as possible, while others say it should be as live as possible to allow the front speakers to produce the correct ambiance. I personally, went the route of Dennis Erskine's personal suggestions and treated the entire front area floor to ceiling with 703. (I also have a "bay window" foundation cutout behind my screen and front speakers.)


----------



## fredpamm

Thanks Stima... I appreciate your input....


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Has diffusion fallen out of favor?



ROFL. The moment we start shipping, you can bet I'll change my tune.


I'm kidding!
























Seriously, there's been a huge amount of interest in our new diffusor, and I'm even getting calls from magazines asking to review them. But when a customer calls and asks, I still explain that absorption is the staple and diffusion is the icing on the cake. Then again, once I load up my own listening room with diffusors to hear them in context properly, maybe I really will change my tune.










I brought a bunch of traps and "HF" panels to a local potential customer not long ago. He had a really nice setup with RPG classic QRD well diffusors all over the place, including at the first reflection points. The diffusors really did help make the room sound larger, but he ended up buying all of the traps we brought plus two more because they made things even more focused.


--Ethan


----------



## Dennis Erskine

Actually, the latest research by Toole, Olive, et. al. strongly suggests that diffusion is very much under used and absorption is very much over utilized.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> ROFL. The moment we start shipping, you can bet I'll change my tune.



RealDiffusors?


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> RealDiffusors?



Yes, I thought that's what you were referring to. We announced a new diffusor last week, and will begin shipping Real Soon Now. In November, anyway.


--Ethan


----------



## Stima

Please don't take this as anything but a friendly gesture.


I have seen a couple other threads closed due to "sales talk" recently.


I would HATE to see this thread locked for that reason.


Again...I mean NO disrespect to anyone. Just looking out for the greater good!


----------



## BasementBob




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Actually, the latest research by Toole, Olive, et. al. strongly suggests that diffusion is very much under used and absorption is very much over utilized.



I don't know if this is the 'latest', but the below quote is from: "Loudspeakers and Rooms - Working Together" by Floyd E. Toole, Ph.D.



> Quote:
> Diffusion refers to the degree of randomness in the directions of arrival of sounds at a point in space. Diffusion in the sound field surrounding a listener in a concert hall is an absolutely essential requirement. It is of some use in home theater rooms. It is of little use in stereo rooms.
> 
> In a concert hall, diffusion helps communicate all of the sound from all of the instruments on stage, to all of the listeners in the audience. If there were total diffusion, listeners would not know where the sounds are coming from, so there must be a balance among direct, reflected and diffuse sounds.
> 
> In a surround sound application, Dolby ProLogic requires low correlation in the sounds arriving at the ears from the surround channel speakers in order to generate a sense of ambiguous spaciousness. In THX systems, electronic decorrelation in the signals sent to the left and right surrounds helps, and bidirectional out-of-phase dipole surround speakers can be of further assistance. The latter is an attempt to increase the diffusion in the sound field. Acoustically dead rooms work against that effort, and irregular reflective surfaces and objects in the room work with it. Unfortunately, the front channels really need to see a relatively dead room, which creates a dilemma that has not been satisfactorily solved. Dolby Digital / AC-3 and DTS multichannel music call for five identical channels and loudspeakers, thus presumably calling for a relatively dead room. On the other hand, multichannel music might well be better in a normally live room. Then there are systems like Lexicon's Logic-7 and Citation 6-axis that go directly to the core issue - five channels are not enough. They add channels in the rear of the room. And so it goes. This issue is not settled yet.
> 
> Conventional two-channel stereo is another real dilemma. Here loudspeakers range from highly unidirectional through multidirectional to omnidirectional. Each category requires different room treatment and positions. Listener preferences cannot be ignored. Some like a large spacious illusion (a relatively live room), others like pinpoint imaging (a relatively dead room).
> 
> A common compromise is to avoid the decision of whether to absorb or to reflect, and opt to diffuse the sound with any one of the several available irregular reflecting devices. A diffuser is an elaborate reflector, in that it sends any incoming sound off in many different directions. This is not a bad idea, and diffusers have an important place in the repertoire of acoustical devices. Just remember that they are still reflectors, and the sound energy is merely redirected. Stereo is a system in which fragile phantom images are an essential part of the illusion. I have been in rooms where many dollars were spent on diffusers which did little more than destroy the stereo image that every other device in the signal path attempted to preserve. One can have too much of a good thing.
> 
> A simple test is to reproduce monophonic pink noise at equal levels through both loudspeakers. For a listener on the axis of symmetry, the result should be a compact auditory image midway between the loudspeakers. Moving the head slightly to the left and right should reveal a symmetrical brightening, as the acoustical-cross talk interference is changed, and the stereo axis should "lock in" with great precision.


----------



## sdurani

Bob, how old is that paper? They still reference old Pro Logic and Citation 6-Axis.


Sanjay


----------



## BasementBob

sdurani:

Good catch. I thought it was the one I downloaded recently, turns out I downloaded it in 2002, and it was written August 1999. So it's not 'latest'.


----------



## Dennis Erskine

Toole's most recent work is published in the AES library.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Toole's most recent work is published in the AES library.



So, has the thinking changed since '99 on the issues discussed in the paper quoted by Bob?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Toole's most recent work is published in the AES library.



His latest paper in the June JAES is actually a review article, not new research. But it is an excellent, detailed presentation of his current "stump speech."


I think he is wrong on some implications (he's pushed for his views as far as he reasonably can in a peer-reviewed journal). This is principally because he does not consider the case of movie soundtrack reproduction in any detail. We cannot necessarily lump this together with multichannel music reproduction. Still, his questions are provocative, and when Floyd Toole talks, we listen.


- Terry


----------



## pepar

Speaking strictly as a layman with only a somewhat educated ear from 40 years of music appreciation and a smattering of live sound reinforcement and studio work, I find the things I knew/thought I knew/assumed about 2-channel reproduction are difficult to reconcile with the 7.1-ness of my current hobby/passion/obsession. While obviously dated, referring to "decorrelation" in THX systems' surrounds when it is now discrete, Bob's Toole quote *does* somewhat address what he considers the needs of the mains vis-a-vis those of the (dipole) surrounds. Perhaps after treating the mains/audience first reflection points with absorption and using a lot of diffusion elsewhere is the way to go. The FRP absorbers would seem to have little effect on sound radiating from the surrounds while the diffusion would help both. Does this make sense at all?


----------



## Dennis Erskine




> Quote:
> when Floyd Toole talks, we listen.



Indeed.







I'm working on a spectral analysis/measurement problem with Todd and Floyd's input is certainly thought provoking.


----------



## Ethan Winer

Terry,


> I think he is wrong on some implications ... when Floyd Toole talks, we listen.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry,
> 
> [snip]
> 
> ... this returns us to whether the listening room should impart its own character onto the playback, versus all desired ambience is already in the recording so the room should add nothing further. The latter approach is the only way a recording can be heard as intended in different rooms. I contend that all needed and desired localization is (or should be) already present in the recording through the use of panning and reverb and ambience effects added by the mix engineer.



Exactly. If you are playing a dry stereo recording of a string quartet and you want it to sound like they are playing right in your livingroom, you want the room to maximally contribute its ambiance. The solution to this was found by Amar Bose, in his invention of the 901 speaker. But today's multichannel recordings require different solutions.


- Terry


----------



## Ethan Winer

Terry,


> The solution to this was found by Amar Bose, in his invention of the 901 speaker. But today's multichannel recordings require different solutions.


----------



## Terry Montlick

I'm agreeing.










My point was that the acoustical goals in the stereo, Bose 901 days were very different from the goals for current multichannel reproduction.


----------



## kiwishred

FWIW, if I really want to hear something clearly, for example pick out a vocal from the entire mix, I put on headphones. That should tell us something about the drawbacks of of additional room ambience shouldn't it ?


The only problem with this approach is the voice seems to be coming from within my head rather than in front of m







.


Brent


----------



## Kal Rubinson




> Quote:
> Originally Posted by *kiwishred* /forum/post/0
> 
> 
> FWIW, if I really want to hear something clearly, for example pick out a vocal from the entire mix, I put on headphones. That should tell us something about the drawbacks of of additional room ambience shouldn't it ?
> 
> 
> The only problem with this approach is the voice seems to be coming from within my head rather than in front of m
> 
> 
> 
> 
> 
> 
> 
> .
> 
> 
> Brent



And skulls are resonant as well.










Kal


----------



## Texas Aggie

I am currently in the design/build stage of a new house. I have read most of these posts(whew!) and will be using the green glue. My room is 28'4' D 18.4' W and 10' H at the screen then 9' for middle tier then 8' for rear tier/entrance.


This will be an upstairs HT over the garage. It will also have a 5.5' deep by 18' W entrance/equipment rm at the rear of the HT. (see pic).


My biggest concern is that my two kids rooms will be upstairs with this room.

Two things that make me feel better are the TWO sealed solid core doors that isolate(hopefully) the hallway and rest of upstairs, AND the staggered stud GG combo.


I worry about transmission through the floor and ceiling plates which I would assume will be connected to the rest of the house. Can I have my builder simply not connect these or is that simply not structually sound?


I think I am close on this but want to run by the experts for some thoughts.



THANKS!!!


----------



## Stima

As always, I preface every reply in this thread with "I AM NOT AN EXPERT!"










That said, you should research "floating floors" and "floating walls" for examples of each. I can't remember the write up I found a few years back that described how to build said items (the book was for building a recording studio in a home...but the same techniques would apply), but I am certain someone here knows of some good reading material.


In a nutshell, for the highest degree of isolation you need to build a second complete room within a room. First, build a new floor that is isolated from the existing floor via elastic material. After you have a new floor you continue with floating walls and then a floating ceiling. Given you have a 10' room height, even though you definitely lose head room with this approach, I still think its a feasible approach.


I would say, if you can't build a floating floor, the MINUMUM you would want to do is get one of those pads you can set your sub on which decouples it from the floor. If you have large woofers in your fronts, you might want to consider getting pads for them as well. Again, I don't know the exact name of what I am referencing, but I know they are out there and are used with good results.


Hope this helps.


----------



## star_gazer

I have noticed a few other posters express concerns about (nearly exposed) fiberglass in reach of small children. I share this concern, but don't know what the alternatives are. Any suggestions? A small price and or performance penalty is acceptable.


Thanks for any input.


----------



## eugovector




> Quote:
> Originally Posted by *star_gazer* /forum/post/0
> 
> 
> I have noticed a few other posters express concerns about (nearly exposed) fiberglass in reach of small children. I share this concern, but don't know what the alternatives are. Any suggestions? A small price and or performance penalty is acceptable.
> 
> 
> Thanks for any input.



You just need some thin polyfill and loose cotton fabric. See the pictures and walkthrough in my thread: http://www.avsforum.com/avs-vb/showthread.php?t=734181


----------



## Stima

Honestly, GOM is VERY thick. You can not see or feel the fiberglass through it. I would honestly have no concerns with only using GOM.


----------



## Terry Montlick

If you want something equivalent in performance to semirigid fiberglass, use acoustic cotton in either 3 pcf or 6 pcf density. This is available from Acoustical Surfaces Inc. under the name " Echo Eliminator":

http://www.acousticalsurfaces.com/ec...cho_photos.htm 


Regards,

Terry


----------



## KERMIE

Guys I know this in not ideal but it is what I have to work with..cosmetics is a part of it (WAF)


Here is a sketch of my room.


i have a wall that comes into play that goes about 2/3 rds of the way, then an opening, then a small wall (2 foot)


The hallway is about 3 feet wide that goes upstairs.


I have base traps floor to ceiling in black in these corners. I know the small wall corner may not do much but it was the WAF again.


What can I do where the yellow Star is and will it make a difference.


----------



## KERMIE

This is not to great scale, the rears are close than they look....


where is says "Wall" that is open


thanks for the help


----------



## TumaraBaap




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Actually, the latest research by Toole, Olive, et. al. strongly suggests that diffusion is very much under used and absorption is very much over utilized.



That's the conclusion I too would draw reading most of the posts here. However, I think Toole's take home point was that reflections, absorption and diffusion when used should not be frequency specific lest it unbalance the off-axis endeavor of the loudspeaker. Absorption and diffusion aren't discussed in great depth. As pointed out on post #1660 and #1671 of this thread, the oomph of his review paper was in the discussion of reflections. Given how entrenched some acoustics ideas are here, I'd anticipate a fair amount of resistance to his enthusiasm for lateral reflections.


Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> Given how entrenched some acoustics ideas are here, I'd anticipate a fair amount of resistance to his enthusiasm for lateral reflections.



My observation in my theater is that eliminating the first reflections coming from the left and right front side walls increased clarity, improved imaging, widened the front sound stage and improved mains/surround integration. Any thoughts on why when that doesn't square with Toole's position?


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> My observation in my theater is that eliminating the first reflections coming from the left and right front side walls increased clarity, improved imaging, widened the front sound stage and improved mains/surround integration. Any thoughts on why when that doesn't square with Toole's position?



This is indeed the opposite of what Toole claims in his paper, with the exception of imaging, which he claims can change size and position. And when it does happen it is not necessarily bad. The width of the soundstage should actually widen with reflections. One reason I hazard to put forth for your observations is that very few loudspeakers will yield a spectrally similar reflection to its on-axis response. The NHT Xd or Linkwitz's Orion just may be one of a kind. Aczel's review of the Orion (which was way before the Toole paper) corroborates just about everything Toole claims in his paper.


In line with conventional wisdom my room currently has side wall absorption. I haven't had time yet to conduct comparisons with and without the absorption. I have a set of B&W CDM1Se's. Like the vast majority of "iconic" brands of loudspeakers on the consumer market, they're hardly up to par. I won't even be bothering with them. It's my Mackie HR624 that I'll run through the paces.


One thing that impressed upon me from the paper is how any acoustic implementation ought to be weighed on its degree of reduction of interaural cross correlation. If what impinges at a given moment in the right ear is different from the left ear, it gives the organ in between a wealth of cues in determining the richness of the sound field. That comb filtering in a room can under certain circumstances be a pleasant thing is not the only surprise in the paper.


Toole is unwaveringly scientific in his approach. Speculation or hard evidence is accordingly delineated. His methods for experiment or literature review rigorously account for bias and confounding effects. What he proclaims should never be taken lightly, my man!


Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> Toole is unwaveringly scientific in his approach. Speculation or hard evidence is accordingly delineated. His methods for experiment or literature review rigorously account for bias and confounding effects. What he proclaims should never be taken lightly, my man!



I hear you. I am not, in any way, trying to refute, but rather trying to understand why my admittedly limited experience is different.



> Quote:
> This is indeed the opposite of what Toole claims in his paper, with the exception of imaging, which he claims can change size and position. And when it does happen it is not necessarily bad. The width of the soundstage should actually widen with reflections. One reason I hazard to put forth for your observations is that very few loudspeakers will yield a spectrally similar reflection to its on-axis response. The NHT Xd or Linkwitz's Orion just may be one of a kind. Aczel's review of the Orion (which was way before the Toole paper) corroborates just about everything Toole claims in his paper.



My speakers are M&K S-150s which are THX Ultra2 certified with very controlled dispersion and off-axis response. Is it possible that by removing confusing early reflections, more of the nuance comes through allowing the listener to more complelely experience the soundfield created by the engineer/producer? My main listening position is in the nearfield; before I added the (six) first reflection point absorbers, it was not.


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> My speakers are M&K S-150s which are THX Ultra2 certified with very controlled dispersion and off-axis response. Is it possible that by removing confusing early reflections, more of the nuance comes through allowing the listener to more complelely experience the soundfield created by the engineer/producer? My main listening position is in the nearfield; before I added the (six) first reflection point absorbers, it was not.



In the vein of aiming for a reduced interaural cross correlation, Toole reports that reflections at 0 degrees and 180 degrees have found to be least beneficial ... both ears are exposed to the same change at the same instant in time. Also most loudspeakers have an uneven off-axis response in the vertical plane. And he says too many reflections can worsen things. So there is no question that broadband absorption (200-300 Hz and above) at the first reflection points on the ceiling, front wall and center portion of back wall can only be a good thing.


Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> In the vein of aiming for a reduced interaural cross correlation, Toole reports that reflections at 0 degrees and 180 degrees have found to be least beneficial ... both ears are exposed to the same change at the same instant in time. Also most loudspeakers have an uneven off-axis response in the vertical plane. And he says too many reflections can worsen things. So there is no question that broadband absorption (200-300 Hz and above) at the first reflection points on the ceiling, front wall and center portion of back wall can only be a good thing.
> 
> 
> Tumara Baap



Perhaps my experience is not so contradictory after all; the absorber that made the BIGGEST difference was the one on the rear wall. The one on the front ceiling was a close second. The "chamber" behind my false wall had been lined with fiberglass from the gitgo, so I had no opportunity to A/B that absorber.


----------



## TAllen01

Just wanted to add my two cents to this thread. I finally found some fiberglas here locally (1.5" thick, Johns Mansville) and made some 2 x 4 panels, beveled edge, with Pearl GOM fabric. Finished about 8 of them (with more to come) in anticipation of placing them around my new theater that will be finished in late April. Could not wait, of course, and placed them around my existing room, which is open at one end. Put on a demo surround DVD, and could not stop smiling!! This really improved the room. I even got out some old SACDs that I had not listened to in a while, and continued the "I can't believe what I am hearing" amazement. Still smiling hours later. So for a few trips to Lowe's for staples and lumber, a trip to a housing insulation contractor, an order on the web for the fabric, and about 20 hours of labor, I am in heaven right now! If you have not treated your room (but you probably have if you are reading this), I highly recommend it!


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> My speakers are M&K S-150s which are THX Ultra2 certified with very controlled dispersion and off-axis response.



I'm not sure what entails THX Ultra2 certification, but the datasheet graph of the Genelec 8040a (at Genelec's website) is an example of an excellent off-axis response. Not only do you have significant dispersion off-axis, but the signature profile of the response is more or less retained at 15, 30, 45 and 60 degrees off axis, only gradually being attenuated in amplitude with increasing angle. While this has been recognized as a desirable attribute for a while, it's becoming clear how absolutely critical it is to have that sort of performance from an acoustics perspective. It ought to be a cardinal requirement and everything else in acoustics follows.


Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> I'm not sure what entails THX Ultra2 certification, but the datasheet graph of the Genelec 8040a (at Genelec's website) is an example of an excellent off-axis response. Not only do you have significant dispersion off-axis, but the signature profile of the response is more or less retained at 15, 30, 45 and 60 degrees off axis, only gradually being attenuated in amplitude with increasing angle. While this has been recognized as a desirable attribute for a while, it's becoming clear how absolutely critical it is to have that sort of performance from an acoustics perspective. It ought to be a cardinal requirement and everything else in acoustics follows.
> 
> 
> Tumara Baap



The THX cert mandates pretty much what you've described as your Genelecs' dispersion and off-axis response; a relatively tightly controlled vertical dispersion and smooth off-axis response in the horizontal plane.


----------



## llj

I would like to find a source for acoustically transparent fabric panels. Think

of a speaker grill, except that I'm looking for a panel size of approximately 2'x4'.


----------



## pepar




> Quote:
> Originally Posted by *llj* /forum/post/0
> 
> 
> I would like to find a source for acoustically transparent fabric panels. Think
> 
> of a speaker grill, except that I'm looking for a panel size of approximately 2'x4'.



Built them yourself?


----------



## KERMIE




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> Guys I know this in not ideal but it is what I have to work with..cosmetics is a part of it (WAF)
> 
> 
> Here is a sketch of my room.
> 
> 
> i have a wall that comes into play that goes about 2/3 rds of the way, then an opening, then a small wall (2 foot)
> 
> 
> The hallway is about 3 feet wide that goes upstairs.
> 
> 
> I have base traps floor to ceiling in black in these corners. I know the small wall corner may not do much but it was the WAF again.
> 
> 
> What can I do where the yellow Star is and will it make a difference.




Any takers on this..


thank you in advance..


K


----------



## bpape

So is that like the end of a hall or a bare wall at the bottom of the stairs or am I missing something?


The first thing I see in that room is that it looks like your seating is centered in the room. Not a good idea.


Bryan


----------



## eugovector




> Quote:
> Originally Posted by *llj* /forum/post/0
> 
> 
> I would like to find a source for acoustically transparent fabric panels. Think
> 
> of a speaker grill, except that I'm looking for a panel size of approximately 2'x4'.



For DIY, most recommend Burlap or a loosely woven natural fiber fabric. www.fabric.com hs burlap in a number of colors. I myself went with some $1/yard fabric from walmart.


----------



## sdurani




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> The width of the soundstage should actually widen with reflections.



Sure, because the speaker and its reflection can create a phantom image (almost a phantom speaker) in between them, stretching the soundstage outside the speaker. While it can sound spectacular (at least it has in my experience), there are a couple of problems that I've noticed.


Sounds at the edges of the soundstage tend to become less clear, maybe because they're being reproduced as multiple mono sources (speaker, reflection and phantom image combine). Also, sounds just inside the L/R speakers can get swamped by sounds just outside. So you get this lush, wide soundstage but things get soft as you move inward of the speakers until you get to the centre. It's actually a little easier to hear this with three speakers up front than with the typical two-speaker front soundstage.


Absorbing side wall reflections tends to restore imaging inward of the speakers (or at least makes them easier to hear) at the expense of a wider soundstage. I don't think one is more right or wrong than the other, just a matter of priorities and personal preferences.


Sanjay


----------



## KERMIE




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> So is that like the end of a hall or a bare wall at the bottom of the stairs or am I missing something?
> 
> 
> The first thing I see in that room is that it looks like your seating is centered in the room. Not a good idea.
> 
> 
> Bryan




bpape,


You come down the stairs and there is a wall on the right side that runs the length of the room. The wall on the left stops about 6 feet from the end of the steps and that is where you enter the theater. Where it says " It is open into the theater area. The short wall was there since the home was built...


The seating is very close to the center at about 10 feet from the front wall and about 7 feet from the back wall...the drawing is not exactly to scale....is that going to give me some problems???


----------



## bpape

OK. Where the star is, I'm not seeing a lot of benefit to doing much of anything.


That seating distance should be pretty good. You're about 60% back unless my math is really bad this early in the morning.


Bryan


----------



## llj

I live in an area with expansive soil. Basements (like mine) are usually built

with "floating floors", and curtain walls hang from the main floor. This provides

for a ~1 inch gap between the bottom of the wall and the floor. As soil moisture

levels vary, the floating floor can move up and down without causing structural

problems.


This creates an acoustic challenge for basement theater builders... the operation

of this 1" gap cannot be interfered with, but most acoustic treatments are based

on application of rigid materials such as wallboard.


Surely, I do not have a unique problem. What's the standard procedure for

acoustically treating the 1" gap between the bottom of a hanging wall, and

a floating concrete slab?


----------



## pepar




> Quote:
> Originally Posted by *llj* /forum/post/0
> 
> 
> I live in an area with expansive soil. Basements (like mine) are usually built
> 
> with "floating floors", and curtain walls hang from the main floor. This provides
> 
> for a ~1 inch gap between the bottom of the wall and the floor. As soil moisture
> 
> levels vary, the floating floor can move up and down without causing structural
> 
> problems.
> 
> 
> This creates an acoustic challenge for basement theater builders... the operation
> 
> of this 1" gap cannot be interfered with, but most acoustic treatments are based
> 
> on application of rigid materials such as wallboard.
> 
> 
> Surely, I do not have a unique problem. What's the standard procedure for
> 
> acoustically treating the 1" gap between the bottom of a hanging wall, and
> 
> a floating concrete slab?



Treat it for what reason? Acoustical isolation from adjoining rooms or acoustical treatment for the room itself? If the former, then it doesn't seem like you can put anything in there. If the latter, I can't see how a 1" area makes any difference.


----------



## ScottJ0007




> Quote:
> Originally Posted by *llj* /forum/post/0
> 
> 
> I live in an area with expansive soil. Basements (like mine) are usually built
> 
> with "floating floors", and curtain walls hang from the main floor. This provides
> 
> for a ~1 inch gap between the bottom of the wall and the floor. As soil moisture
> 
> levels vary, the floating floor can move up and down without causing structural
> 
> problems.
> 
> 
> This creates an acoustic challenge for basement theater builders... the operation
> 
> of this 1" gap cannot be interfered with, but most acoustic treatments are based
> 
> on application of rigid materials such as wallboard.
> 
> 
> Surely, I do not have a unique problem. What's the standard procedure for
> 
> acoustically treating the 1" gap between the bottom of a hanging wall, and
> 
> a floating concrete slab?



No, you do not have a unique problem. Try treating it like this...











This treats it for both sound isolation and for in-room acoustics.


This topic was discussed in depth a while back. Try a search on "floating walls". I tried to find the link for you, but the search engine is disabled right now.


- Scott


----------



## cubedude

Okay, I've been reading up on acoustic treatments for months. I'm taking all next week off, and the in-laws just cancelled on coming out here for Thanksgiving, so I'm hoping to grab the opportunity to get some acoustic treatments into my home theater (5.1, BTW).


The room is 15x18' with the screen along the 18' wall. One side wall is mostly windows, the other has two doors, one in the middle and one in the back corner.


My plans:


-DIY Absorbers on the front wall, as much as possible. I'd really rather not cut rigid fiberglass.


-Bass traps in front corners, floor to ceiling.


-Side walls: Floor to ear height treated with more absorbers.


-Floors are already carpeted.


-Rear wall/floor corner: I'm talking about the corner behind the seating that's made by the rear wall and floor. Since I've got my projector there anyways, no one can walk behind the seating, so I was going to put another corner bass trap there.


-Ceiling: Not planning anything. I'd like to, but I didn't even trust myself with building the shelf for my projector, I'm not going to even try hanging acoustic treatments.


Now, one side wall is mostly windows, which presents a problem. I've heard that I should put *diffusion* opposite the windows. Opinions?


So, any glaring mistakes or omissions?


----------



## bpape

Hard to make general statements like diffusion opposite windows. As soon as you do, there will be a situation where it's not right. Personally, I prefer to put curtains over the windows and absorbtion on the opposite wall.


If this yields too much HF absorbtion, then consider not doing the whole bottom up to ear level thing to compensate.


Bryan


----------



## Stima




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Hard to make general statements like diffusion opposite windows. As soon as you do, there will be a situation where it's not right. Personally, I prefer to put curtains over the windows and absorption on the opposite wall.
> 
> 
> If this yields too much HF absorption, then consider not doing the whole bottom up to ear level thing to compensate.
> 
> 
> Bryan



I second Bryans opinion. Cover those early reflection points no matter where (side wall, ceiling, ect.) they occur.


----------



## jojos960

Stupid newbie question here.....I thought the front projection wall was typically painted in a dark flat paint like black or gray for refectivity purposes but reading through this thread, it appears I should be acoustically treating the front wall. Do people just use a dark GOM for their front walls? I seem to remember seeing alot of HT pics where the front wall appeared painted dark????


----------



## eugovector




> Quote:
> Originally Posted by *jojos960* /forum/post/0
> 
> 
> Stupid newbie question here.....I thought the front projection wall was typically painted in a dark flat paint like black or gray for refectivity purposes but reading through this thread, it appears I should be acoustically treating the front wall. Do people just use a dark GOM for their front walls? I seem to remember seeing alot of HT pics where the front wall appeared painted dark????



Yep, black GOM, Walmart Bedsheets, whatever. You can also shoot for a neutral grey if you prefer that look.


----------



## Andrew Hornfeck

I used 1.5" Knauff for my front wall and from 8' to 3' for my others. I simply DID the front wall because it seemed reasonable, but the rest I installed beadboard below 3' since it wasn't necessary from a primary reflection point (to treat) unless I were sitting on the floor! I actually have my sheetrock screen ON the front studs. I then added a 2x2 frame on top of it to 'establish' the screen. Casing the 2x2's yeilds a 1-1/2" boarder around the screen -- it looks very professional. Oh, and once all these marerials are installed, there is a natural pocket for the treatment to go.


I used Black for the front wall, Deep Burgundy for the rest and Medium Grey 'diamond' accents. So, YES, the front wall appears Black.


----------



## cubedude




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Hard to make general statements like diffusion opposite windows. As soon as you do, there will be a situation where it's not right. Personally, I prefer to put curtains over the windows and absorbtion on the opposite wall.
> 
> 
> If this yields too much HF absorbtion, then consider not doing the whole bottom up to ear level thing to compensate.
> 
> 
> Bryan



I've already got fairly thick curtains over the windows, so I'll scratch the diffusors.


There actually won't be much bottom-up-to-ear-level absorption on the side walls, probably 6-8' wide at most.


Now, I forgot to ask about the rear wall. Should I put absorption across from the screen or leave it as is? I think that if I had any more absorption than what I've already got planned the room will be way too dead, so I'm inclined to leave it as is, with the exception of the bass trap I mentioned earlier.


----------



## bpape

Well, on the back wall, you can put up some absorbtion but with an FSK facing on it. That will help tame nulls off the rear wall in the bottom end without sucking up any more of the highs.


Bryan


----------



## Stima




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Well, on the back wall, you can put up some absorbtion but with an FSK facing on it. That will help tame nulls off the rear wall in the bottom end without sucking up any more of the highs.
> 
> 
> Bryan



If you are equating "bottom end" absorption to bass management, I don't know if I can agree with that comment. Even 2" thick fiberglass will not provide much "bottom end" absorption. From everything I have read, bass traps need to be thicker and spaced off a wall to provide any significant benefits.


Please correct me if I am wrong as I am always learning things.


----------



## pepar




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> If you are equating "bottom end" absorption to bass management, I don't know if I can agree with that comment. Even 2" thick fiberglass will not provide much "bottom end" absorption. From everything I have read, bass traps need to be thicker and spaced off a wall to provide any significant benefits.
> 
> 
> Please correct me if I am wrong as I am always learning things.



You are correct.


----------



## bpape

To a point - yes. However, even 2" thick material provides SOME absorbtion in the lower frequencies. No - it's not going to have a 1.0 coefficient. BUT, enough square footage with even a .25 coefficient will provide a cumulative effect. The trick is to not overdo the rest of the spectrum at the same time.


Compare 2" of unfaced to 2" of FRK:


2" 703 Plain on wall - 0.17 0.86 1.14 1.07 1.02 0.98


2" 703 FRK on wall - 0.63 0.56 0.95 0.79 0.60 0.35


2" 705 FRK on wall - 0.60 0.50 0.63 0.82 0.45 0.34


As you can see, the faced material is significantly better in the bottom end but not going to overdo the top in the grand scheme of things. That many square feet of .6 at 125Hz is not an insignificant amount of absorbtion.


Will it be effective at 40Hz? No. Not much will. Will it still provide SOME additional control in the 50's to 250Hz range where many bottom end issues exist and the ringing masks a lot of the dialog? Absolutely.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Compare 2" of unfaced to 2" of FRK:
> 
> 
> 2" 703 Plain on wall - 0.17 0.86 1.14 1.07 1.02 0.98
> 
> 
> 2" 703 FRK on wall - 0.63 0.56 0.95 0.79 0.60 0.35
> 
> 
> 2" 705 FRK on wall - 0.60 0.50 0.63 0.82 0.45 0.34
> 
> 
> As you can see, the faced material is significantly better in the bottom end but not going to overdo the top in the grand scheme of things. That many square feet of .6 at 125Hz is not an insignificant amount of absor*p*tion.



Membrane effect?


----------



## BasementBob

pepar:


> Quote:
> [FRK]membrane effect



Yep.

What you look for is a fall, rise, fall pattern -- and that's a tell tale of a membrane effect.

And a low, little higher, little higher, higher, is indicitive of a porous effect (in octave bands).

In this case

2" 705 FRK on wall - 0.60 0.50 0.63 0.82 0.45 0.34

There's a rise at 125hz, a fall at 250hz, a rise rise at 500hz to 1000hz, a fall at 2000hz.

So, no porous effect (the kraft is towards the room), and two resonances (probably).


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> pepar:
> 
> 
> Yep.
> 
> What you look for is a fall, rise, fall pattern -- and that's a tell tale of a membrane effect.



Of course, as the room frequencies approach the resonant frequency of the membrane, it begins to vibrate taking that energy out of the room.


----------



## cubedude




> Quote:
> Originally Posted by *Stima* /forum/post/0
> 
> 
> If you are equating "bottom end" absorption to bass management, I don't know if I can agree with that comment. Even 2" thick fiberglass will not provide much "bottom end" absorption. From everything I have read, bass traps need to be thicker and spaced off a wall to provide any significant benefits.
> 
> 
> Please correct me if I am wrong as I am always learning things.



Now, as bpape just mentioned, bass ringing that masks dialog is a problem I'm trying to correct. Would having 7 2x4' panel bass traps straddling three different corners help this? Or should I build two column-type bass traps and place it in two of the corners?


----------



## pepar




> Quote:
> Originally Posted by *cubedude* /forum/post/0
> 
> 
> Now, as bpape just mentioned, bass ringing that masks dialog is a problem I'm trying to correct. Would having 7 2x4' panel bass traps straddling three different corners help this? Or should I build two column-type bass traps and place it in two of the corners?



Have you done any acoustical testing? Ethan has a file on his website that burns to a CD that can be used with a Radio Shack meter to roughly graph your room's response.


----------



## cubedude




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Have you done any acoustical testing? Ethan has a file on his website that burns to a CD that can be used with a Radio Shack meter to roughly graph your room's response.



I'll do that tonight or tomorrow and report back. I have a Radio Shack meter that I used to calibrate the system.


edit: My laptop's audio IO isn't playing well with RoomEQ Wizard, so I'm going to have to buy a USB soundcard or fiddle with it quite a bit to get it to work. I'll see what I can do but I don't have my hopes up.


----------



## rockemsockem

I just made my second set of panels, and these came out much better than my first set. My 1st ones were a terrible color, and even though they were only 2'x2x, they were too big.


This time I cut the 2x4 panels into 18"x36"x2", and picked a burlap that better matched the room. I used some Celotex rigid fiberglass from my local menards, 1 roll of quilt batting, and 5 ft. of burlap. Total cost $30. I already had a can of 3M adhesive.


----------



## bpape

General bottom end decay time control can help with dialog issues quite effectively.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *cubedude* /forum/post/0
> 
> 
> edit: My laptop's audio IO isn't playing well with RoomEQ Wizard, so I'm going to have to buy a USB soundcard or fiddle with it quite a bit to get it to work. I'll see what I can do but I don't have my hopes up.



Rarely do laptops have full duplex onboard audio required by software like REW. Fortunately, they work well with the least expensive Sound Blaster USB "card."


----------



## BasementBob

pepar:

Actually, my laptop doesn't work with the soundblaster USB card, although it does have a USB port. And you're right that ETF5 also doesn't work with my laptop's audio (which can be shut off). (My laptop was free from my IT department after my asking the question: "What do you have that you can't give away")


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> pepar:
> 
> Actually, my laptop doesn't work with the soundblaster USB card, although it does have a USB port. And you're right that ETF5 also doesn't work with my laptop's audio (which can be shut off). (My laptop was free from my IT department after my asking the question: "What do you have that you can't give away")



My laptop(s) automatically turn off onboard audio when the SB USB is plugged in. Is your laptop an older model?


----------



## BasementBob

pepar:



> Quote:
> Is your laptop an older model?



Oh yea.

I wanted something to surf the net with (not something I do with my development computers). It has no software installed that didn't come with the operating system, other than a virus checker. It has very little memory, and the CPU is so slow that I can instantly detect when malware starts to run because even the most efficent malware slows down this slow laptop perceptibly. That's not a planned/wanted feature, that's just the way it is. I can type into notepad and watch the TaskManager performance hit 50%. The LCD doesn't work (I'm using a Samsung SyncMaster 970e - very nice). It takes 15 minutes to boot, and another 15 to log on. CPU usage never drops below 5%.


Frankly I probably wouldn't have enjoyed running ETF5 on it anyway, but there was a day I really really tried. (Purchased copy of RplusD is installed on my testing computer)


----------



## bogg

i was doing some experimenting in my listening room/theater that I just finished trying to get the best setup for the GIK Acoustics panels that I bought. I have the 4" panels in the front corners, 2" panels at the side first reflection points, and used to have 2 2" panels on the front wall reflection points. I currently am running just a stereo setup with Tyler Linbrook Signature monitors. After getting the speakers in the best place in my 13X12 room, I still noticed that the center of the soundstage wasn't articulate enough, especially given imaging and soundstage that the speakers can give. So on a whim I moved the 2 2" panels off the front wall and put them right behind each speaker (actually leaning on them), so that it blocks any path from the speakers to the front wall at all. Now the soundstage and imaging are perfect.


I realize that many damp their entire front wall, but for me that was not an option. I wonder if anyone else actually puts treatments right on or next to their speakers and whether this is actually not a good thing? It sure sounds better, particularly with the Audyssey auto EQ in my Denon receiver.


----------



## cubedude




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Rarely do laptops have full duplex onboard audio required by software like REW. Fortunately, they work well with the least expensive Sound Blaster USB "card."



I have a old PowerBook, so I'll have to see what works with OSX and REW. I'll check around a bit and see what I can find.


----------



## mikeryan




> Quote:
> Originally Posted by *cubedude* /forum/post/0
> 
> 
> I have a old PowerBook, so I'll have to see what works with OSX and REW. I'll check around a bit and see what I can find.



cubedude,


It's always nice to hear about other Mac users. I'm in the very early construction phase and am lusting to upgrade to a new Intel MacBook







, so I'm pretty sure Windows on Parallels or Boot Camp will be a fallback option for me by the time I'm in that phase. Anyway, I'll be interested to hear what you find.


Mike


----------



## cubedude




> Quote:
> Originally Posted by *mikeryan* /forum/post/0
> 
> 
> cubedude,
> 
> 
> It's always nice to hear about other Mac users. I'm in the very early construction phase and am lusting to upgrade to a new Intel MacBook
> 
> 
> 
> 
> 
> 
> 
> , so I'm pretty sure Windows on Parallels or Boot Camp will be a fallback option for me by the time I'm in that phase. Anyway, I'll be interested to hear what you find.
> 
> 
> Mike



I wish I could afford a MacBook right now, but I'm still saving up for an anamorphic lens and video processor.










Anyways, I asked just asked about the Griffin iMic over in the REW thread, so I'll see if anyone over there knows anything about it.


----------



## pepar




> Quote:
> Originally Posted by *bogg* /forum/post/0
> 
> 
> i was doing some experimenting in my listening room/theater that I just finished trying to get the best setup for the GIK Acoustics panels that I bought. I have the 4" panels in the front corners, 2" panels at the side first reflection points, and used to have 2 2" panels on the front wall reflection points. I currently am running just a stereo setup with Tyler Linbrook Signature monitors. After getting the speakers in the best place in my 13X12 room, I still noticed that the center of the soundstage wasn't articulate enough, especially given imaging and soundstage that the speakers can give. So on a whim I moved the 2 2" panels off the front wall and put them right behind each speaker (actually leaning on them), so that it blocks any path from the speakers to the front wall at all. Now the soundstage and imaging are perfect.



The area on the wall behind the LCR speakers is a first reflection point. So's the ceiling. And many times overlooked - the back wall.


----------



## bpape

Actually, directly behind and directly beside the speakers deal more with SBIR - which is still a good thing.


Bryan


----------



## bpape

Actually, directly behind and directly beside the speakers deal more with SBIR - which is still a good thing.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Actually, directly behind and directly beside the speakers deal more with SBIR - which is still a good thing.
> 
> 
> Bryan



So, being *that* close makes those surfaces boundaries in addition to first reflection points? Within a certain distance based on wavelength?


----------



## bpape

Not sure I understand the question. Those places directly around the speaker offer the opportunity for the spherical wavefront of the bass frequencies to bounce off and combine with the direct, front moving waves in either a constructive or destructive manner - either creating a peak or dip in response. Treating those surfaces with appropriate materials reduces the intensity of the reflected waves, thereby reducing the effect of the constructive or destructive combining of the waves.


The frequencies which are most affected are those where the distance from the baffle to the surface and back to the baffle are equal to or 1/2 of the length of the wave in question. Those where it is equal will have a peak (coming back in phase with the direct signal), those at 1/2 will have a dip (coming back 180 degrees out of phase with the direct signal, thereby causing a cancellation).


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Not sure I understand the question. Those places directly around the speaker offer the opportunity for the spherical wavefront of the bass frequencies to bounce off and combine with the direct, front moving waves in either a constructive or destructive manner - either creating a peak or dip in response. Treating those surfaces with appropriate materials reduces the intensity of the reflected waves, thereby reducing the effect of the constructive or destructive combining of the waves.
> 
> 
> The frequencies which are most affected are those where the distance from the baffle to the surface and back to the baffle are equal to or 1/2 of the length of the wave in question. Those where it is equal will have a peak (coming back in phase with the direct signal), those at 1/2 will have a dip (coming back 180 degrees out of phase with the direct signal, thereby causing a cancellation).
> 
> 
> Bryan



Seems like you understood it just fine.


----------



## TumaraBaap

I'm not sure why you perceive a benefit. However, when using professional loudspeakers, broadband absorption behind the speaker can be useful. First you would have to engage the acoustic space switch for placement near a wall. Doing so rolls off the bass for a flat response. The 1/4 wavelength from the loudspeaker face to the wall behind is small enough that the SBIR frequency of relevance will be both more directional, (and therefore will not radiate rearwards to the same extent as deeper bass) and the little that will radiate is within the performance frequency range of the broadband absorber being used.


In order to minimize SBIR with a regular consumer loudspeaker, one can use a sub with the crossover engaged (80 to 90 Hz) and place the loudspeaker 4 feet or more out into the room. The SBIR frequency in question will then be low enough that the processor would have handed over that job from the loudspeaker to the subwoofer.


Tumara Baap



> Quote:
> Originally Posted by *bogg* /forum/post/0
> 
> 
> So on a whim I moved the 2 2" panels off the front wall and put them right behind each speaker (actually leaning on them), so that it blocks any path from the speakers to the front wall at all. Now the soundstage and imaging are perfect.


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> I'm not sure why you perceive a benefit. However, when using professional loudspeakers, broadband absorption behind the speaker can be useful. First you would have to engage the acoustic space switch for placement near a wall. Doing so rolls off the bass for a flat response. The 1/4 wavelength from the loudspeaker face to the wall behind is small enough that the SBIR frequency of relevance will be both more directional, (and therefore will not radiate rearwards to the same extent as deeper bass) and the little that will radiate is within the performance frequency range of the broadband absorber being used.
> 
> 
> In order to minimize SBIR with a regular consumer loudspeaker, one can use a sub with the crossover engaged (80 to 90 Hz) and place the loudspeaker 4 feet or more out into the room. The SBIR frequency in question will then be low enough that the processor would have handed over that job from the loudspeaker to the subwoofer.
> 
> 
> Tumara Baap



"professional loudspeakers" = "full range" ?


"regular consumer loudspeaker" = "sat/sub" ?


(Got the Toole paper on deck for review. Thanx!)


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> "professional loudspeakers" = "full range" ?



It may or may not be full range. What I had in mind was an active monitor, with built-in amplifiers and electronic crossover. These will almost always be sonically superior (and hence more amenable to room acoustics) than similar size consumer loudspeakers irrespective of price. They will typically have an acoustic space switch for placement near a wall or corner. Examples of which are Mackie HR624, Genelec 8040a, Dynaudio BM5a ... all of which can make for truly excellent and versatile HT speakers. Some placement options such as near a wall also yield additional benefits such as superior dynamic headroom, lower distortion, minimizing SBIR, permitting more usable room space, and reducing cable clutter on floors. I have a processor with balanced XLR outs such as B&K Reference 50 S2. Outlaw Model 990 is an alternative.


Tumara Baap


----------



## BasementBob

TumaraBaap:



> Quote:
> Some placement options such as near a wall also yield additional benefits such as superior dynamic headroom, lower distortion, minimizing SBIR,



Can you give a few more words on that topic please?


----------



## TumaraBaap




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> TumaraBaap:
> 
> 
> Can you give a few more words on that topic please?



Most people are already aware that a subwoofer will play more efficiently when placed against a wall versus out in the room. The same goes for a loudspeaker. Bass sucks up most power, and when those demands are reduced, the ability of the loudspeaker to play everything else with aplomb improves. However you cannot attenuate the bass on a consumer loudspeaker with the precision of a dedicated acoustic space switch. Turning down bass on the receiver by 2 decibels or blocking speaker ports are crude measures. I would still keep loudspeakers about 3 feet away from the closest lateral surface, as I believe that plays a role in how the mid and upper frequencies "illuminate" the room.


The benefits of this approach are similar to those of "soffit mounting" or "flush mounting" monitors in high-end recording studios or screening rooms designed by top acousticians, though of course not to the same extent. Proper flush mounting also completely eliminates edge diffraction. (though that was never a significant distortion to begin with ... rounding off cabinet edges for example probably has more to do with vagaries of fashion). Genelec's web site at http://www.genelec.com/support/flushmount.php has some good info on the SBIR phenomenon and the advantages of soffit mounting. But soffit mounting correctly is hideously expensive and hampers future changes and upgrades. However, I can get fairly close to reaping at least some of the benefits with careful positioning and setting up of my Mackie HR624's.

Tumara Baap


----------



## bpape

In order to effectively use soffit mounting, one must use a speaker that is designed for that. It's not simply edge diffraction but also how the crossover is designed in terms of baffle step compensation - which will be totally messed up if soffit mounted and no way to compensate.


Also, simply crossing a speaker over at 80Hz doesn't do anything to eliminate SBIR - it simply removes the lower few octaves to a speaker better designed and more flexible in placement for smoothest response. SBIR will have an effect well up into the hundreds of Hz.


Bryan


----------



## electronrx

I am severely limited in my options for room treatments(WAF). I got the big TV an speakers and she gets the majority of the aesthetics. I was hoping someone could give me a "real world" thought on use plants as a supplement to soft furniture area rugs and a few bass traps in the corner. My room is about about 15x19 and has an angled ceiling. The right side is 9 feet and slants up to about 13-14 feet. I use it 70/30 HT/2channel. The linked website shows the absorbant coefficients of certain plants. Could I put the ficus at the first reflection point of my mains and expect any improvemnets?Any thoughts? Am I hoping for too much??


P.S I am a newbie

http://www.ri-research.com/tropplan/...c/acoustic.htm


----------



## eugovector

Hang treatments in a complementary color and put a plant in front of it. I really like the way mine turned out and think they add to the aesthetics, not detract from it. Let you wife go to the fabric store and pick out the fabric, any loosely woven, natural fiber fabric will work.



> Quote:
> Originally Posted by *electronrx* /forum/post/0
> 
> 
> I am severely limited in my options for room treatments(WAF). I got the big TV an speakers and she gets the majority of the aesthetics. I was hoping someone could give me a "real world" thought on use plants as a supplement to soft furniture area rugs and a few bass traps in the corner. My room is about about 15x19 and has an angled ceiling. The right side is 9 feet and slants up to about 13-14 feet. I use it 70/30 HT/2channel. The linked website shows the absorbant coefficients of certain plants. Could I put the ficus at the first reflection point of my mains and expect any improvemnets?Any thoughts? Am I hoping for too much??
> 
> 
> P.S I am a newbie
> 
> http://www.ri-research.com/tropplan/...c/acoustic.htm


----------



## Ethan Winer




> Quote:
> Originally Posted by *electronrx* /forum/post/0
> 
> 
> I was hoping someone could give me a "real world" thought on use plants as a supplement to soft furniture area rugs and a few bass traps in the corner.



Don't expect much from plants. Maybe _really_ big plants can help reduce the worst of the echoes a tiny amount. But all rooms need absorption well down into the bass range, and no plants will help there.


--Ethan


----------



## TumaraBaap

Simply plopping a monitor into a wall not specifically designed for soffit mounting will invariably color the sound. But those with the money and intention to undertake such projects usually know better. Even Mackie HR824's have been successfully soffit mounted with provision for redirection of rear passive radiator output and the requisite outboard equalization.


The topic of soffit mounting was brought up to shed light on a few acoustic principles. I doubt anyone here will actually commit to something so unwieldy ... who knows, this is the dedicated theater forum and WAF is as good as it gets...


When optimizing loudspeaker placement in conjunction with subwoofer crossover for its effect on SBIR, the operative word is amelioration, not elimination. What matters is that having a loudspeaker 4 feet away from the wall behind, instead of say 2 feet away, will yield advantages. Whereas a frequency is almost obliterated at where distance from transducer to wall is 1/4 wavelenth, there are further tooth-like distortion dips across the bass spectrum. Judicious loudspeaker placement/ crossover selection will ameliorate (not eliminate) that distortion profile.


Tumara Baap



> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> In order to effectively use soffit mounting, one must use a speaker that is designed for that. It's not simply edge diffraction but also how the crossover is designed in terms of baffle step compensation - which will be totally messed up if soffit mounted and no way to compensate.
> 
> 
> Also, simply crossing a speaker over at 80Hz doesn't do anything to eliminate SBIR - it simply removes the lower few octaves to a speaker better designed and more flexible in placement for smoothest response. SBIR will have an effect well up into the hundreds of Hz.
> 
> 
> Bryan


----------



## bpape

Agreed. Your previous post(s) seemed to color you a proponent for just the opposite - as in getting everything close to a boundary to 'engage the acoustic space'.


... and you'd be amazed how many people try to build subs into cubicles in walls, put speakers inside shelving units (just as bad if not worse than in-wall mounting), etc.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Don't expect much from plants. Maybe _really_ big plants can help reduce the worst of the echoes a tiny amount. But all rooms need absorption well down into the bass range, and no plants will help there.



A VERY large Venus Flytrap next to his wife's seat may help.


----------



## nowandthen

I posted this in a new thread but no one responded so I'll ask in here.


I have extra Acoustik mat. When building my front stage would it help to put Acoustik mat between the plywood layers instead of 30# roofing felt?


If not then I will sell the extra Acoustik mat. If it helps, fine! I'll still have extra Acoustik mat just not as much.










I already have a layer of Acoustik mat between my concrete slab and my 2 x10 framing (that is filled with sand).


Stack up is as follows


3/4" plywood

roofing felt or Acoustik mat?

1/2" plywood

roofing felt or Acoustik mat?

3/4" plywood

2x10 framing, 1' on center, filled with sand

3/4" plywood

Acoustik mat

concrete slab


Thanks!


edit to add 3/4" plywood between framing and Acoustik mat


----------



## bpape

If you want to use 1 layer of the mat, that'd be fine. I think 2 is a bit of overkill. If you can get some money back out of it, go for it. Heaven knows you'll go over budget elsewhere! If not, then it certainly won't hurt to use it.


Bryan


----------



## nowandthen

Thanks Bryan! Hope you get caught up soon. I'm waiting to hear from you!


----------



## KERMIE

When you are looking at RT60 values. What is it that you want to have as an optimum RT60 value after treatments.


Also, is there a starting point or a calculator that shows "approximate" square footage of treatment based on room size, speaker location...etc.


for example my room is 17 x 12 x 8 - carpet on a pad and false ceiling tiles at this time.


thanks


----------



## pepar




> Quote:
> Originally Posted by *KERMIE* /forum/post/0
> 
> 
> When you are looking at RT60 values. What is it that you want to have as an optimum RT60 value after treatments.
> 
> 
> Also, is there a starting point or a calculator that shows "approximate" square footage of treatment based on room size, speaker location...etc.
> 
> 
> for example my room is 17 x 12 x 8 - carpet on a pad and false ceiling tiles at this time.
> 
> 
> thanks



There are a few Excel spreadsheets available for download that will do this. Some are very detailed with hundreds of materials with acoustical properties integrated into the sheet. Selecting a material and inputting the surface area that it covers results in its properties being incorporated into the overall room equation.


----------



## BasementBob

Kermie:



> Quote:
> is there a starting point or a calculator that shows "approximate" square footage of treatment based on room size


 http://www.bobgolds.com/Mode/RoomModes.htm 



> Quote:
> Computed Information:
> 
> Room Dimensions: Length=17 ft, Width=12 ft, Height=8 ft
> 
> Room Ratio: 1 : 1.5 : 2.12
> 
> R. Walker BBC 1996:
> 
> - 1.1w / h
> - l
> - no integer multiple within 5%: Pass
> 
> Nearest Known Ratio:
> 
> - "7) M. M. Louden: 1971: 3rd best ratio" 1 : 1.5 : 2.1
> 
> RT60 (IEC/AEC N 12-A standard): 238 ms
> 
> - ±50ms from 200Hz to 3.5kHz = 188 to 288ms
> 
> - ±100ms above 3.5kHz = 138 to 338ms
> 
> -


----------



## KERMIE

Thanks BasementBob - I will have to study some of that info to understand what half of that means. I will surf arounc bobgold.com to help understand.


thanks


----------



## BasementBob

KERMIE:

The best book I've ever read on RT60 calcs for studio design is How to Build A Small Budget Recording Studio From Scratch : With 12 Tested Designs by Michael Shea


----------



## skijunkie

I wasn't sure where I should post this question, but is seems mainly an acoustical question. I've done searches throughout the forums and can't seems to find anything on this specific topic. Most sound isolation searches come back with green glue and drywall techniques.


I am interesting in sound isolation pads to place underneath my speakers (honestly only my sub really needs a pad). They currently sit on/in a cabinet and transfer some of their vibrations to the cabinet. DIY methods or cost effective bought pads are what I am looking for.


In my search I did see one picture of a person who put their sub on a scap piece of carpet padding, but the thread made no mention if it helped or not. Anyone have any ideas that would help?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *skijunkie* /forum/post/0
> 
> 
> I wasn't sure where I should post this question, but is seems mainly an acoustical question. I've done searches throughout the forums and can't seems to find anything on this specific topic. Most sound isolation searches come back with green glue and drywall techniques.
> 
> 
> I am interesting in sound isolation pads to place underneath my speakers (honestly only my sub really needs a pad). They currently sit on/in a cabinet and transfer some of their vibrations to the cabinet. DIY methods or cost effective bought pads are what I am looking for.
> 
> 
> In my search I did see one picture of a person who put their sub on a scap piece of carpet padding, but the thread made no mention if it helped or not. Anyone have any ideas that would help?



Do a search for the Auralex SubDude or Gramma.
http://www.stereophile.com/musicinth...itr/index.html


----------



## pepar




> Quote:
> Originally Posted by *skijunkie* /forum/post/0
> 
> 
> I wasn't sure where I should post this question, but is seems mainly an acoustical question. I've done searches throughout the forums and can't seems to find anything on this specific topic. Most sound isolation searches come back with green glue and drywall techniques.
> 
> 
> I am interesting in sound isolation pads to place underneath my speakers (honestly only my sub really needs a pad). They currently sit on/in a cabinet and transfer some of their vibrations to the cabinet. DIY methods or cost effective bought pads are what I am looking for.
> 
> 
> In my search I did see one picture of a person who put their sub on a scap piece of carpet padding, but the thread made no mention if it helped or not. Anyone have any ideas that would help?



Suspend it?


----------



## Ktulu_1





> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> Do a search for the Auralex SubDude or Gramma.
> http://www.stereophile.com/musicinth...itr/index.html


 "Auralex Subdude a MUST HAVE!!"


----------



## skijunkie

Thanks! After reading about the subdude I ordered one.


----------



## nvarner

Acoustical Masters---I have a question. My HT is finally to the point where I can ask this question...Can I create my fabric panels with OC Pink Foamboard 3/4? ( I got a great deal on 4 pieces).

My HT room is in my basement. The left side wall is all concrete, the front wall is 1/2 concrete, and the right wall has a window and is 1/3 concrete. I have insulated the walls which are studded 16oc with rock wool and I've blown insulation into the ceiling. There are 2 layers of 1/2 drywall with gg and the whole font wall, back wall and the top side walls are covered in 3/4 Oak HardwoodPlywood which is gg'ed and nailed into studs.The floor will have carpet and I have installed an 3/4 OSB subfloor. I am only putting the gom fabric on the bottom half ( at about 49"). My LCR speakers are inside a column built ofthe 3/4 Oak and my sub is in a hidden window seat which is located at about the first 1/3 of the room (about 8 feet in the room).


----------



## pepar




> Quote:
> Originally Posted by *nvarner* /forum/post/0
> 
> 
> Acoustical Masters---I have a question. My HT is finally to the point where I can ask this question...Can I create my fabric panels with OC Pink Foamboard 3/4? ( I got a great deal on 4 pieces).
> 
> My HT room is in my basement. The left side wall is all concrete, the front wall is 1/2 concrete, and the right wall has a window and is 1/3 concrete. I have insulated the walls which are studded 16oc with rock wool and I've blown insulation into the ceiling. There are 2 layers of 1/2 drywall with gg and the whole font wall, back wall and the top side walls are covered in 3/4 Oak HardwoodPlywood which is gg'ed and nailed into studs.The floor will have carpet and I have installed an 3/4 OSB subfloor. I am only putting the gom fabric on the bottom half ( at about 49"). My LCR speakers are inside a column built ofthe 3/4 Oak and my sub is in a hidden window seat which is located at about the first 1/3 of the room (about 8 feet in the room).



You could create panels with that stuff, but it would not do much more than keep your room warmer. It is an insulation, not an acoustical absorber.


----------



## nvarner

Thanks pepar! Having said that then I guess you would reccomend that I get some linacoustic or something to put behind the fabric. Do you think that would add anything to the sound quality? Just trying to see if the extra money for the linacoutic is justifiable.


----------



## pepar




> Quote:
> Originally Posted by *nvarner* /forum/post/0
> 
> 
> Thanks pepar! Having said that then I guess you would reccomend that I get some linacoustic or something to put behind the fabric. Do you think that would add anything to the sound quality? Just trying to see if the extra money for the linacoutic is justifiable.



I'm not an expert, but I can say that from my experience most rooms benefit from absorbers at the first reflection points. I've got 2" OC SelectSound Black, but some recommend 4". For me that would have have negative aesthetics.

Here is a helpful chart listing absorption coefficients of "Fiberglass, Rockwool, Polyester, Cotton, and Sheep." (I think they mean "wool" for the last one, at least I hope they do.)


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I'm not an expert, but I can say that from my experience most rooms benefit from absorbers at the first reflection points. I've got 2" OC SelectSound Black, but some recommend 4". For me that would have have negative aesthetics.



Yup. Absorbers at first reflection points kill two birds with one stone: They reduce said reflections to prevent poor accuracy in localizing the front sound stage, and they add general wide-band absorption which lowers reverberation time to reduce the intrusion of the room's own acoustical signature on that of the recorded sound.


1" of rigid or semi-rigid fiberglass is all you need for first reflections, but 2" or more extends the absorption to lower frequencies. It's generally a practical and space issue. High performance rooms are professionally designed to yield an optimal sound treatment for room geometric, aesthetics, and the specific listening needs/preferences of the owner.


Regards,

Terry


----------



## Grayson73

I have a 'music' room with grand piano, drums, and guitars. The room has 2 windows and is hardwood floor, so it is VERY loud and sound is reflecting off the walls and floor. The piano's upper keys are especially harsh.


I am looking into buying an 8'x10' wool rug for the floor.


Any low-cost suggestions for the walls?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Grayson73* /forum/post/0
> 
> 
> Any low-cost suggestions for the walls?



Rigid fiberglass wrapped in soft open weave fabric is the standard material for DIY acoustic treatment.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Yup. Absorbers at first reflection points kill two birds with one stone: They reduce said reflections to prevent poor accuracy in localizing the front sound stage, and they add general wide-band absorption which lowers reverberation time to reduce the intrusion of the room's own acoustical signature on that of the recorded sound.
> 
> 
> 1" of rigid or semi-rigid fiberglass is all you need for first reflections, but 2" or more extends the absorption to lower frequencies. It's generally a practical and space issue. High performance rooms are professionally designed to yield an optimal sound treatment for room geometric, aesthetics, and the specific listening needs/preferences of the owner.



If I were to build another home theater, I'd build the room and then build a room inside of that so that absorption/diffusion/whatever would present smooth walls, as opposed to the "wall hangings" I have now protruding into my room. I guess this would be like the panelized systems commercially available.


----------



## hardax

Picking up a set of two tri-traps to see if they make a big difference in my basement home theater.


Just wondering if anyone has an opinion if these should go in the back corners of my room or the front corners?


I do have my sub in the front left corner of the room so it kind of seems silly to have a bass trap directly behind that?


Thanks all.


----------



## BasementBob

hardax:


If it's a very powerful sub, the sub probably shouldn't be in the corner anyway.

If it's a weak sub (i.e. underpowered for the room) then put your absorption as far away from it as possible (the back), and leave your sub in the front corner.

Putting broadband absorbers/traps on the front corners may help imaging/speach, at the cost of reducing envelopment/spacousness a bit.

I've seen people put deep absorbers on top of their front corner subs, and at least one manufacturer sells absorbers to go under front corner subs.


----------



## hardax

Thanks for the reply BasementBob.


My sub is pretty powerful. It is a HSU STF-3 in a room aproximately 19x24x7.


doing the crawl test I did determine that the front left corner was the best place for it.


Based on the above do you still think they should go in the front or the back?


Thanks


----------



## Grayson73

Someone found sheets of fiberglass backed ceiling panels (2' x 4')(1" thick), $4.74 each at Menards. Is this similar to OC 703? If so, sounds like a great low cost solution!


Unfortunately, there is no Menards near me. Any other ideas of where I can find this?


----------



## pepar




> Quote:
> Originally Posted by *Grayson73* /forum/post/0
> 
> 
> Someone found sheets of fiberglass backed ceiling panels (2' x 4')(1" thick), $4.74 each at Menards. Is this similar to OC 703? If so, sounds like a great low cost solution!
> 
> 
> Unfortunately, there is no Menards near me. Any other ideas of where I can find this?



Without knowing anything about the stuff at Menard's, it's impossible to say. There are a number of different types/densities with different properties.


----------



## ccapozzoli

Where is the best place to purchase Mass loaded Vinyl?

Thanks

Chris


----------



## longfellowfan

In the near future I will building some bass traps. I have some questions though. Each trap will be 2'x4' My traps will consist of 2" thick mineral wood and 2 pieces of OC 705 2" thick apiece all covered with GOM fabric. My question is what should I use to bond the mineral wood with the 2 pieces of fiberglass. Should I use chalk or glue or some spray on adhesive glue or maybe even green glue. Input on this subject would be much appreciated.


----------



## BasementBob

longfellowfan:


Why not just make the GoM into a bag. Then you won't have to bond them together with anything. Or wrap the mineral/705 up in GoM like a christmas present, and glue the GoM to at the back, using 3M 77 spray adhesive.


Chalk wouldn't hold.

Certainly don't use green glue in a porous absorber.


I don't know what mineral wood is. I thought it might have been a typo, but you did it twice. Mineral wool is anything that's made out of rocks (mineral) that have been made into fibers (wool). So mineral wool includes rockwool and fiberglass. 705 is made of fiberglass.


With your corner absorbers now being 6" thick, you might want to use 703 instead of 705. It's probably cheaper too, unless you already have 705 lying around.


----------



## longfellowfan

Mineral wood showing here


----------



## Grayson73

Anyone try fiberglass ceiling panels from Lowes or Home Depot? It's called "Strata", yellow on one side and white on the other. (2'x4') one inch thick.


EDIT: Apparently, the person got it from Menards. Has anyone checked Lowes or Home Depot for fiberglass panels? I'll check this weekend.


----------



## causeofhim




> Quote:
> Originally Posted by *longfellowfan* /forum/post/0
> 
> 
> Mineral wood showing here



What would work better for room panels, mineral wool or 703?


----------



## causeofhim




> Quote:
> Originally Posted by *mark haflich* /forum/post/0
> 
> 
> Your floor should be carpeted but do not use a foam or rubber pad. Horse hair jute is the best but is generally no longer available because of youths smoking it for the hemp. 1/2 inch felt padding to me is the next best thing BUT put the bonding surface side down (normal carpet insulation is to put it up so that the tape the installers use to hold pad sections together will not tear the pad).



I may have missed this but, why would you not want to use a foam or rubber pad under the carpet?


----------



## bpape

703 is more user friendly for panel construction but mineral wool will work and is cheaper - as long as you don't jostle it too much - crumbles easily.


On the floor pad, the foam or rubber will do nothing to assist with absorbtion. The felt or jute will effectively thicken the absorbtive layer ande broaden the frequency range over which it is effective.


Bryan


----------



## longfellowfan




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> 703 is more user friendly for panel construction but mineral wool will work and is cheaper - as long as you don't jostle it too much - crumbles easily.
> 
> 
> 
> Bryan



Could I then use one layer of mineral wood as the back with 2 layers of 703 2" thick apiece in front with a frame and wrap it in GOM fabric.


----------



## causeofhim

It's not actually wood. It's mineral wool.


----------



## longfellowfan

So I am a skim reader and it looked like wood my bad.


----------



## pepar

Thank goodness! I was thinking I had to pressure treat all my trim.


----------



## longfellowfan

So here is what the wife and I want to do. My room is 16x11x8. The room is a living room and wear we watch all of our movies.( I may post pics later some older pic are in my signature. I wanted to by two panel bass traps for the back two conners being 2'x4' and 4 to 6" thick. We also want 4 absorption panel 2'x2' 2 to 4" thick for the first reflection point and 2 for the back wall of the room. I wanted to simply buy them but my wife want to go the diy method so she can pick out the fabric from GOM and it is a little cheaper for diy. I was going to use a pine frame to around the absorption material and wrap it in GOM Fabric. My question is what to use as the absorption material. 4 to 6" of 703 for bass traps and 2 to 4" of 703 for the absorption panels. I am open to suggestions I am not going to built them for a few month after my wife goes over the fabric color samples and a income tax refund comes. Thanks in advance.


----------



## causeofhim

Can someone give me some ideas about my basement theater area. The room is 30'x12' with a strange layout. The large window opening on the left side is open to a playroom and the large doorway behind the theater is open to a small kitchenette.











I plan on acoustical treatment surrounding the projection screen. I'm not sure if I should do the whole wall or just a few feet aroundthe screen, behind the speakers. I really dont have any side walls. Should I place acoustical treatment behind the seating on the back wall? What about bass traps?


Thanks


----------



## Warpdrv

Could someone give me some suggestions on what I should or might be able to do with reguards to accoustic treatment, and toning down the Bright/reflective nature of this room..


http://i34.photobucket.com/albums/d1...r/IMG_1643.jpg 
http://i34.photobucket.com/albums/d1...r/IMG_1642.jpg 
http://i34.photobucket.com/albums/d1...r/IMG_1641.jpg 
http://i34.photobucket.com/albums/d1...AVsetup003.jpg 
http://i34.photobucket.com/albums/d1...12Plus2006.jpg 


Im not sure what company's are out there, asthetically pleasing.. form and function..


thanks


Warp


----------



## Ethan Winer




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> Can someone give me some ideas about my basement theater area.



My first suggestion is to rearrange things so you're not right in front of a wall. That's where the inevitable peaks and nulls are worst.


> Should I place acoustical treatment behind the seating on the back wall? 
What about bass traps?


----------



## Ethan Winer

Warps,


Nice clock!


> Could someone give me some suggestions on what I should or might be able to do with reguards to accoustic treatment, and toning down the Bright/reflective nature of this room.


----------



## cyberbri

There's no picture of what it looks like directly behind the couches.


That would be a challenging room, especially without moving anything around. It's in a corner itself, facing out, without many real "corners" to put bass traps in. Plus the walls and ceilings are extremely high.


You can't put a 1st ref absorber in front of the fireplace (well, you could...) or a big bay window (I actually have a panel in front of a window - and a very understanding wife - see this picture ). The left side, where the window is, probably isn't too bad for direct reflections, because it's so open.


A panel behind the TV might help, as would some bass traps in corners, if you have any regular corners that could hold bass traps. Triangular columns, like GIK Acoustic's Tri-Traps , allow you to add bass traps that don't stand out like big acoustic panels.



The rest depends on how many panels you are willing to put on the walls. I suggest getting fabric to match the color of your walls so they don't stand out like sore thumbs - unless you're divorced and don't have a wife to worry about.











But for starters, covering more of your hardwood floor with a bigger rug, especially directly in front of the speakers, is something that is relatively painless.


----------



## cyberbri




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> Can someone give me some ideas about my basement theater area. The room is 30'x12' with a strange layout. The large window opening on the left side is open to a playroom and the large doorway behind the theater is open to a small kitchenette.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I plan on acoustical treatment surrounding the projection screen. I'm not sure if I should do the whole wall or just a few feet aroundthe screen, behind the speakers. I really dont have any side walls. Should I place acoustical treatment behind the seating on the back wall? What about bass traps?
> 
> 
> Thanks




Project onto the left wall, not the top wall. Rerrange everything around that.


----------



## cyberbri

Just a quick question about placing panels on the front wall behind the center speaker.


I have a left-over 2" thick panel (4" w/ frame) that I currently have stacked between two bass trap panels in the front right corner. It would take some effort to put it on the front wall behind the TV/center speaker, but if it would be worth it for sound quality, I'll do it.


What benefits could I expect by putting the 2'x4' panel on the wall behind the center speaker here?


(Note - image was taken before panels purchased)











This is one side my room w/ the panels (center channel seen on left edge of picture) and very close to what it looks like now:


----------



## causeofhim




> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> Project onto the left wall, not the top wall. Rerrange everything around that.



I cannot. There is not enough room on that wall to project a picture. That would be much nicer if it was possible.


----------



## cyberbri

A wall 12' wide isn't big enough to project a picture?


----------



## causeofhim




> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> A wall 12' wide isn't big enough to project a picture?



The wall is not 12' wide. There are two doors and an opening in that 12' space.


----------



## eugovector




> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> A wall 12' wide isn't big enough to project a picture?



The diagram is a little confusing, but I think he has a doorway and window on that wall.


Maybe a pull down screen?


----------



## causeofhim

It really can only work with the rest of the basement if it is configured the way that it is. I just have to design my theater to work with what I have.


----------



## cyberbri

Back to my question - what benefit would there be to putting an absorber panel behind the center channel on the front wall?


----------



## eugovector




> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> Back to my question - what benefit would there be to putting an absorber panel behind the center channel on the front wall?



Sound radiates in all direction from a speaker (stick your head back there, it's alittle muffled, but it's there). By putting some absorption at the first reflectionpoint behind thespeaker, you'll improve clarity. Not as beneficial as hitting the first reflection points on your sidewalls (and back wall in my opinion), but if you've already done those, it definately can't hurt.


P.S. Unlike many in this forum, I'm no professional when it comes to this stuff. I just know from personal experience.


----------



## cyberbri




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Sound radiates in all direction from a speaker (stick your head back there, it's alittle muffled, but it's there). By putting some absorption at the first reflectionpoint behind thespeaker, you'll improve clarity. Not as beneficial as hitting the first reflection points on your sidewalls (and back wall in my opinion), but if you've already done those, it definately can't hurt.
> 
> 
> P.S. Unlike many in this forum, I'm no professional when it comes to this stuff. I just know from personal experience.




Thanks. The sides are covered (no pun intended). I just had the third extra panel left over and it's just between two thicker bass trap panels in the front right corner. If I can get around to it, I'll try to put it up on the front wall.


----------



## Tiga

Hello everyone, I'm still in the planning stages of my theater as my basement remodeling project gets underway. I'm currently working on the adjacent bathroom and will move to the theater next. (hopefully I can get some pictures up). I've been trying to educate myself as much as I can by reading from this forum. I've got to get my theater moving quickly as we are having a baby in July.







Consequently I have to scale things back - including the theater budget.










Anyway - my question is will plain old pink fluffy fiberglass insulation work for treating the screen wall? My thought is I would attach 2x3 furring strips to the poured concrete wall, two layers of rigid foam insulation between strips, then attach two layers of drywall (with GG depending on budget). From there I thought I could build a false wall/proscenium a few inches back and staple in some R-13. I would then cover the wall in fabric and a nice velvet curtain. The wall is only 10' 6" wide and will have columns built into the sides (~ 10" wide) to cover some piping. Will this effective treat the screen wall? I'm planning on a 100" screen. Thank you all for the help.


David


----------



## eugovector




> Quote:
> Originally Posted by *Tiga* /forum/post/0
> 
> 
> Hello everyone, I'm still in the planning stages of my theater as my basement remodeling project gets underway. I'm currently working on the adjacent bathroom and will move to the theater next. (hopefully I can get some pictures up). I've been trying to educate myself as much as I can by reading from this forum. I've got to get my theater moving quickly as we are having a baby in July.
> 
> 
> 
> 
> 
> 
> 
> Consequently I have to scale things back - including the theater budget.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Anyway - my question is will plain old pink fluffy fiberglass insulation work for treating the screen wall? My thought is I would attach 2x3 furring strips to the poured concrete wall, two layers of rigid foam insulation between strips, then attach two layers of drywall (with GG depending on budget). From there I thought I could build a false wall/proscenium a few inches back and staple in some R-13. I would then cover the wall in fabric and a nice velvet curtain. The wall is only 10' 6" wide and will have columns built into the sides (~ 10" wide) to cover some piping. Will this effective treat the screen wall? I'm planning on a 100" screen. Thank you all for the help.
> 
> 
> David



I think it's been noted several times in this thread that the pink stff will do nothing more than keep your room warm.


I'd just look to do it right the first time. I got 12 sheets of 2inch 703 for $120 shipped from ejdavis. Assumming your wall is 10'x6', this will be more than enough to do your whole wall. Even if you have to pay $200 to do it, it will be worth it to do it right.


In case you need anecdotal evidence to convince you, I've hung 8 pieces of 2 inch 703, framed and covered in my 13x14 livingroom/theater. My girlfriend, who loathes my constant tweaking, and wierd stuff hanging on the wall, has begrudgingly admitted, unsolicited, that dialogue is much clearer now and that she can tell the difference, especially when she watches movies at a friends house.


12 sheets of 703 - $120

Fabric, PolyBatting, and Frames - $80

Vindication from the girlfriend/wife - Priceless


In short, it's the best $200 I've put in my audio this year.


----------



## Tiga

Thanks Eugovector, I've been trying to get through this whole thread but it's a daunting task (63 pages).


I'll pass on the pink insulation then. Is the 703 typically installed right onto the drywall or should it be moved back a few inches? Another question I have is fabric - I see a lot of folks using fabric from GOM or Dazian - is there an accoustical consideration here or is it because of design? I guess what I'm asking is can I use any old fabric on this wall as I'm most likely putting a curtain in front of it? Thanks again!


----------



## eugovector




> Quote:
> Originally Posted by *Tiga* /forum/post/0
> 
> 
> Thanks Eugovector, I've been trying to get through this whole thread but it's a daunting task (63 pages).
> 
> 
> I'll pass on the pink insulation then. Is the 703 typically installed right onto the drywall or should it be moved back a few inches? Another question I have is fabric - I see a lot of folks using fabric from GOM or Dazian - is there an accoustical consideration here or is it because of design? I guess what I'm asking is can I use any old fabric on this wall as I'm most likely putting a curtain in front of it? Thanks again!



Anyone else, feel free to chime in...pretty much everything I know, I learned in forums like these (and this one specifically), so you are technically my source.


Tiga,


I think there is a question here of what you are trying to achieve. Most of the time, by treating a front wall, you are creating a "dead end", a wall that will not create unwanted reflections that mask/muddy the sound created by the main speakers. You'll want to treat all frequencies equally (not just high or mid).


To this end, you will want 2" of 703 outside the drywall. If you space it out 2 inches, all the better (you'll extend slightly the lower frequency absorption). This won't absorb a lot of low, low bass frequencies, but if you're going to put 4" of 703 anywhere, the tri-corners are a more effective spot.


To cover, I used thin cotton fabric from the $1 bin at walmart (and I think it looks great). Natural fibers is the key. Hell of alot cheaper than GOM, easier to find, just as effective, and not bad looking (though not as duriable).


Some curtains are designed to absorb sound. If you are going to put a sound absorbing curtain up, you can probably save putting insulation on the front wall. These curtains can be very expensive though, and hard to find. You can also stick with the 703, not even cover it all all (though I would put a layer of polybatting over the top to keep the fibers in) and get an acoustcally transparent curtain. This may not be the velvety look that you are going for.


The trouble with shiny, velvety curtains made from synthetic fibers is that some are actually very reflective. Put these in front of your 703, and it's like the 703 isn't even there. If this is what you have your eyes on, ust make sure that you get a very large curtain that, when hung, will have lots of folds in it. This will act to difuse the sound, i.e., send it out in all directions instead of straight at your ears. Make sure that you have plenty of absorbtion on your side walls, and this would still help to make you sound more defined.


----------



## vfrjim




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> 
> 12 sheets of 703 - $120
> 
> Fabric, PolyBatting, and Frames - $80
> 
> Vindication from the girlfriend/wife - Priceless
> 
> 
> In short, it's the best $200 I've put in my audio this year.



What size sheets are those? How long did it take to arrive after ordering them? Did you use a piece of plywood on the backs of those panels or just frames around them? Your pictures were not detailed in the making of them.


Thanks


----------



## eugovector




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> You just need some thin polyfill and loose cotton fabric. See the pictures and walkthrough in my thread: http://www.avsforum.com/avs-vb/showthread.php?t=734181



Post 18 in this thread. Stadard 2x4x2", no plywood.


----------



## ekdo




> Quote:
> Originally Posted by *JBS* /forum/post/0
> 
> 
> OK, this seems straightforward from searching AVS and studying theater wall treatment...
> 
> 
> FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.
> 
> CEILING: No acoustical treatment - none, nada.
> 
> FLOOR: Thick, plush carpet is fine.
> 
> 
> But here's where it gets confusing, and I need help...
> 
> 
> SIDEWALLS
> 
> A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.
> 
> --or--
> 
> B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.
> 
> 
> These 2 theories seem to contradict each other. So which is it?
> 
> 
> 
> BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:
> 
> 
> Owens Corning Select Sound Black Acoustic Board
> 
> Owens Corning Fiberglas 703 Series duct insulation.
> 
> Johns Manville Insul-Shield
> 
> Johns Manville Linacoustic Permacoate rolls.
> 
> Certainteed Certpro Acoustaboard Black
> 
> Knauf Duct board EI-475
> 
> Knauf Duct liner EM
> 
> 
> ...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.




Just wanted to find out out whether the insul-shield product (like Linacoustic) goes on top of drywall? or do you attach it directly to the studs?


----------



## BasementBob

eugovector



> Quote:
> I think it's been noted several times in this thread that the pink stff will do nothing more than keep your room warm.



From a practical point of view, that's sort of true.


But actually, as it gets thicker, the adding denser stuff does nothing, because the lower frequency sound doesn't go through it, it just sort of bounces off.

If you're building an absorber that's more than 12" deep, fluffy fiberglass pink is the stuff to use. Not rigid fiberglass.

But for 2 inches, or 2 inches with a 2 inch air gap, rigid is the way to go.

http://www.bobgolds.com/Suntower/Abs...fiberglass.gif


----------



## BasementBob

Tiga


GoM is acoustically transparent (more or less), and fire resistant. Fire resistant is a big plus when you start doing entire walls with it.



If you're curious, you may as well read this if you haven't already.
http://www.infinitysystems.com/homea...nf-rooms_3.pdf 



I'm not saying that I'm recommending this, or that it's a good idea, but I covered a significant amount of my front wall in absorption.
http://www.bobgolds.com/LivingRoomPl...ction/home.htm


----------



## Tiga

Thanks Bob - so it sounds like if I can find a fabric that is acoustically transparent I'm ok. I'm thinking about going with a medium grey fabric around the screen wall with a dark blue curtain going across the front. However I'm considering building out the columns around the corner piping out to the screen and placing the speakers inside of these and covering them with an acoustically transperent fabric and skipping the curtain.


Just curious if others regret using a curtain? Any issues with it. cleaning nightmare? Thanks.


----------



## causeofhim




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> My first suggestion is to rearrange things so you're not right in front of a wall. That's where the inevitable peaks and nulls are worst.
> 
> 
> --Ethan



I will not be able to move the seating off the wall. What can I do to keep the peaks and nulls to a minimum?


----------



## cyberbri

Bass traps, lots. But still, room boundaries (right next to walls) are the worst spots in the room for bass.


----------



## eugovector




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> I will not be able to move the seating off the wall. What can I do to keep the peaks and nulls to a minimum?



Use RoomEQ wizard and a BFD to EQ your sub. You'll be able to kill your peaks, and boost your nulls slightly, but don't get carried away.


----------



## causeofhim




eugovector said:


> Use RoomEQ wizard and a BFD to EQ your sub. QUOTE]
> 
> 
> I'm sorry but you may as well be speaking Dutch. I dont know what any of those letters stand for. But, thanks for trying.


----------



## cyberbri




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> 
> 
> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Use RoomEQ wizard and a BFD to EQ your sub.
> 
> 
> 
> 
> I'm sorry but you may as well be speaking Dutch. I dont know what any of those letters stand for. But, thanks for trying.
Click to expand...



Room EQ Wizard is a freeware program for taking instant measurements of frequency response (need: computer, SPL meter, tripod, cables)


BFD = Behringer Feedback Destroyer, $100 piece of pro audio equipment people use as a customizable "parametric eq" to equalize subwoofer output to attain flatter frequency response


----------



## BasementBob

eugovector:


Once upon a time, Room EQ Wizard was written to make setting the Behringer Feedback Destroyer DSP1124P and FBQ2496 easy. Last I heard, they were no longer for sale. This is the list of currently available equalizers 


Room EQ Wizard should be good for doing room measurements though. Instead of an SPL, I'd use a pre-amp and a microphone such as the ECM8000 .



causeofhim:

EQ is Equalization. In this case it's multiple parametric equalization filters. Each of these has a center frequency and bandwidth (bell curve center and width), and an amplitude -- basically a boost percentage or cut percentage. It gives you the ability to make some frequencies louder or quieter. If you have a modal peak(s), that's too low to absorb, PEQ (parametric equalization) can be used to tame it/them a bit.


----------



## eugovector




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> eugovector:
> 
> 
> Once upon a time, Room EQ Wizard was written to make setting the Behringer Feedback Destroyer DSP1124P and FBQ2496 easy. Last I heard, they were no longer for sale. This is the list of currently available equalizers


 Behringer-Feedback-Destroyer-Pro-DSP-1124P 


You can also find them all day long on ebay. Look into the BFD 1100 also, it's what I use, is identical except for a lower sampling rate, works perfectly with REQW, and can be found on the cheap.


This system costs hundreds less then systems from sub companies such as velodyne, offers much more customizability, and improves your low end significantly. For a $150 investment, everyone with a decent sub should invest in this solution.


The hometheater shack has a great forum post about a wish list for a product that Behringer could make specifically for hometheater subs. Everytime behringer make a product announcement, I hold my breath hopeing that they will, officialy, enter the Home Theater market.


----------



## Ethan Winer




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> I will not be able to move the seating off the wall. What can I do to keep the peaks and nulls to a minimum?



The best (only, really) solution is a broadband absorber that's as thick as possible so it works well to low frequencies.


--Ethan


----------



## BasementBob

eugovector:



> Quote:
> The hometheater shack has a great forum post about a wish list for a product that Behringer could make



I'd read it. I concur that it's a great post.









The day I read it I was looking for something in that forum that said what Behringer products Room EQ Wizard currently suported. I haven't played with Room EQ Wizard myself. I've used RplusD which lists the parameters (frequency, bandwidth, boost) for as many filters as you'd care to try.

Nice to hear that it works with something else.

I was looking at Behringer FBQ2496 the other day on their website -- it comes with a Panic button.










Going far far the other way in terms of money is this gaget http://www.audyssey.com/faq.html


----------



## causeofhim

Do you think that 2" 703 would be enough or should I try to make it 4"?


----------



## eugovector




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> Do you think that 2" 703 would be enough or should I try to make it 4"?



I'm not even sure where are you putting the abosrbers yet. Behind you?


I hate to say it, but you've got a little bit of a mess here. Maybe you could post some pics or a different sketch? I'm just not seeing a lot of options.


How tall is your ceiling? Where are your speakers?


Going from the info that you've given, I'd put 2" panels on the wall behind you and at the 1st reflection points behind the front/center speakers. Put 2" on the ceiling and a thick rug/carpet on the floor if it isn't already carpeted. Put 4" at the corners where 2 walls and the ceiling meets as much as possible, and use the Room EQ/BFD solution described to try to tame other peaks.


Ethan will tell you that te BFD solution will do nothing to tame how long the waves bounce around the room, only how loud they are when they do (you can take out boominess, but not droning/smearing). He'll also tell you that you should cover every wall intersection in your entire room in 4" fiberglass (and, other than being overzealous, he's probably right). But, for a cheap, unobtrusive bandaid, the $100 BFD does wonders.


----------



## causeofhim




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> I'm not even sure where are you putting the abosrbers yet. Behind you?
> 
> 
> I hate to say it, but you've got a little bit of a mess here. Maybe you could post some pics or a different sketch? I'm just not seeing a lot of options.
> 
> 
> How tall is your ceiling? Where are your speakers?
> 
> 
> Going from the info that you've given, I'd put 2" panels on the wall behind you and at the 1st reflection points behind the front/center speakers. Put 2" on the ceiling and a thick rug/carpet on the floor if it isn't already carpeted. Put 4" at the corners where 2 walls and the ceiling meets as much as possible, and use the Room EQ/BFD solution described to try to tame other peaks.
> 
> 
> Ethan will tell you that te BFD solution will do nothing to tame how long the waves bounce around the room, only how loud they are when they do (you can take out boominess, but not droning/smearing). He'll also tell you that you should cover every wall intersection in your entire room in 4" fiberglass (and, other than being overzealous, he's probably right). But, for a cheap, unobtrusive bandaid, the $100 BFD does wonders.



I'll post a different pic when I get home later tonight. My ceiling is 7'6" and I will have a 5.1 set-up. The two fronts will be on each side of the screen with the center directly below. The rears will be on each side of the seating, facing the seating. The sub will be on the front wall, with the screen, I'm not sure where yet.


I was planning on placing 1" on the screen wall and ceiling reflection points and then placing 2"-4" on the back wall (behind our heads). Do you think I should go 2" everywhere? The floor had thick pad and carpet now.


I hope that helps.


----------



## eugovector




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> I was planning on placing 1" on the screen wall and ceiling reflection points and then placing 2"-4" on the back wall (behind our heads). Do you think I should go 2" everywhere? The floor had thick pad and carpet now.



2" is significantly more effective, just ask Bob:

Bob Gold's Extensive Measurements 


2" is kind of the sweetspot for sound-suck. 4" minimum is the rule for bass absorption.


----------



## causeofhim




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> I would not use the 2" material...it will very likely be too absorptive.



I was using info from this thread. It seems that the consensus on here that 1" is the "sweet spot".

If people think that 2" would be better in my situation, I will use it.


----------



## eugovector




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> I was using info from this thread. It seems that the consensus on here that 1" is the "sweet spot".
> 
> If people think that 2" would be better in my situation, I will use it.



I'm not sure where the 1" comes from. The idea behind broadband absorption is that you want to absorb all frequencies equally, so you're not changing the tonal response of your room.


Now some rooms need a little tuning. If you have lots of hard reflective surfaces, you may want to focus on the high frequencies with 1". If you have a smaller room that has bass problems, but you don't want to make it too dead (can sound like listening to your room with a headcold, just very unnatural), you can used faced (FRK) fiberglass (better low end absorption, much less high end absorption).


But, a safe starter solution is almost always attacking 1st reflection points with broadband. This will help with dialogue clarity in movies and definition in music. In my experience, probably the biggest improvement you can make in a system for $150.


Then, look at low end control. This will balance your sound so it doesn't seem boomy or too thin. Try the BFD for an inexpensive half-solution, and add some corner traps as time, money, space, and significant others will allow.


From there, you can hit up the rest of the room with more absorption if it's too live, or diffusion if it's starting to sound dead (diffusion should also help to expand the listening sweetspot).


To others out there: Am I off on any of this?


----------



## Daniel Hutnicki

My situation is a little tricker I would guess. I am moving into a house with an attached garage. The original owner closed off the garage and made it into a room with a dropped ceiling. I have been in this has before as I know the current owner and I would imagine that the garage has no real insulation as its hot in the summer and cold inthe winter.


I am not planning on doing any real construction to this room. Both the front wall where the screen would be and the right wall have long built in closets that go from one end of the wall to the other. They have metal folding doors.


I am going to replace the dropped ceiling tiles with black accoustic tiles.


I guess my question is, what should I do about the screen wall and the right wall. As my wife wont let me close off the closets space, at the very least I will need to change out the metal doors to wood.


Is there anything I can do to treat these wood closet doors which basically will wind up being the side and screen wall and secondly, as the rear and left walls are completely walls and cannot be touched, is there anything I can do for them


Although its not part of the topic, but woild placing insulation of over the top of the dropped ceiling and possibly in the closets help with the heat and cold.


----------



## christer W.

Have read most of this thread. Lots of opinions! Am ready to apply some treatments using panels of 1" Knauf duct board, which I was able to find locally without trouble as opposed to 703, which has eluded me. Acoustic properties are close.


My question has to do with how to treat rear wall ompared to the front wall. My screen is painted directly to the drywall, so getting an absorbing material behind it is not going to be possible, unless you count the R11 behind the drywall already. I will make panels to surround the screen as best I can. The images below are what the room looks like, although there have been some minor changes.


The general consensus I have been able to glean is that the panels for first refelction points along the side walls need to extend from floor to ear height, more or less.


What about the rear wall? Should these extend from floor to ceiling, or continue with the ear height concept? Should I make the panels on the rear wall thicker than the front wall?


I am sure that if I build a dozen or do panels for the room, I will improve the sound quality over that of my drywall box regardless, but it would be nice to have made the most out of my effort.


I am planning using the mirror method to help me locate the panels for the side walls and maybe for the ceiling as well, although I will have to see how this all looks. The dimensions of the room are approx. 23' front to back 12' wide along the screen wall, and 15' wide at the seating area. Preliminarily, my plans are as follows. I hope that someone will leap in and either applaud me, rescue me from ruin, or offer a couple of tweaks:











I will flank the screen with panels along the left and beneath. I have a new PJ, and have grown the screen size to the right almost to the wall to the right and up, almost to the ceiling, so ther is no option to the right or above.


Along the left wall where the left channel and sub sit there will be a panel coming out of corner about 3' towards the sconce shining down as well as a matching one in the opposite corner. The speakers have been change to Klipsch Heresys for the front line, sitting on the floor. I will have panels behind these. Going down the right wall will be floor to ear height panels at probably two reflection points.

























Looking back to the rear, you can't see because I compressed the images too much, but there are two rear surround in-walls that will impact how I treat this surface. A bass trap straddling the corner from floor to ceiling is planned but may be no more than a double layer of the 1" board (foil backing removed). It is the rest of the rear wall that I am unsure of. How tall should they be? Ceiling height at the rear of the room is barely 7'. I am thinking about a panel on the door. What about the rest of that wall? With the equipment rack where it is, trapping across the rear corner is not going to work. All the cabling emerges from a good sized opening behind the equipment. What would anyone suggest for this corner? Coming down the wall from the equipment rack corner I will place probably two panels at the reflection points. This has been complicated by the addition of a relatively large free-standing open shelf which replaces the black shelf shown in the pictures. I will have to pull it out from the wall to determine the locations for these panels. If you want to see all the pictures of my completed room, take a look here: http://www.chriswhitworth.com/complete.htm 


I am looking forward to this project to tighten up my sound. I can tell it just isn't what it should be. Will be very grateful to anyone offering some advice.


Christer Whitworth


----------



## causeofhim

That is a nice little theater! Those seats look pretty comfy for having a slim profile.


----------



## cyberbri

Very nice room.


A few questions...


So the screen isn't centered on the wall, but up against the right wall (you say the screen has grown to the right wall)? Meaning the right speaker is basically up against the right wall? That's how it looks in the pictures, anyway. And now the speaker is in front of the screen?


Ideally the screen would be centered and the speakers would be much further away from the side walls, symmetrically spaced from the front and side walls. That would be ideal, even if it meant reducing the size of the screen slightly.


Can you center the seating and screen in the room? That would be the absolute best for the sound, and allow you to properly place 1st ref point absorbers on the sides.


But the speakers should also be moved forward more, away from the front wall. You can place bass panels in the front corners, either straddling the corner, or cut into triangles and turned into wedges. Do the rear right corner, but don't worry too much about the corner behind the equipment rack. If you treat the other three corners, you're already doing much better than most people, even here on AVS.


----------



## eugovector

What are the areas that you feel your sound is lacking? Is dialogue unintelligible? Boomy or flabby bass? Instrument imaging lacking?


My opinion, if this were my room:


Front wall: the off center screen is throwing me. You're going to wind up w/ asymetrical sound regardless w/ center channel off center, more so if you treat one side of the wall. With no room for a bass trap in the right corner, I'd leave the front as is, with the possible exception of treating the 1st reflection points behind the speakers themselves. If you can bring the fronts forward a bit, and have enough room, then try a bass trap in the right corner (superchunk style)


Side Wall: 1st reflection points for sure (all the speakers, don't miss center, side, or back), sandwich 2 layers to give you 2". Focus on ear level, don't need to go to the floor or the ceiling.


Rear wall: Put 2 inch on as much as possible, focusing on the first reflection points. Bass trap in corner? Why not. Once again, Superchunk seems to be the easiest and most effective (fiber cut into triangles and stacked in corner to make a solid fiberglass tri-post)


Ceiling: 1st reflection point between your center channel and your seating positions.


Speaking of bass traps, if your material is anything like 703, you'll want 4 inches (had this pointed out to me when I asked a similar question). 2 inches won't do much of anything (trust me, I've tried and had Room EQ wizard confim that I was wasting my fibergass)


----------



## eugovector




> Quote:
> Originally Posted by *causeofhim* /forum/post/0
> 
> 
> That is a nice little theater! Those seats look pretty comfy for having a slim profile.




If those are the poyang (sp?) chair, they are amazing comfy (and should be for over $100 for wood and a pad). They have a new chair that looks like the poyang, only cheaper, stay away!


----------



## eugovector

That was my first reaction too, but he says the screen is painted on. Re paint, I guess, is an option.



> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> Very nice room.
> 
> 
> A few questions...
> 
> 
> So the screen isn't centered on the wall, but up against the right wall (you say the screen has grown to the right wall)? Meaning the right speaker is basically up against the right wall? That's how it looks in the pictures, anyway. And now the speaker is in front of the screen?
> 
> 
> Ideally the screen would be centered and the speakers would be much further away from the side walls, symmetrically spaced from the front and side walls. That would be ideal, even if it meant reducing the size of the screen slightly.
> 
> 
> Can you center the seating and screen in the room? That would be the absolute best for the sound, and allow you to properly place 1st ref point absorbers on the sides.
> 
> 
> But the speakers should also be moved forward more, away from the front wall. You can place bass panels in the front corners, either straddling the corner, or cut into triangles and turned into wedges. Do the rear right corner, but don't worry too much about the corner behind the equipment rack. If you treat the other three corners, you're already doing much better than most people, even here on AVS.


----------



## Winkelmann

Chris,

Other than the tweaks you know you need, you might want to move the left speaker the same distance from the center of the screen as the right speaker. An SPL monitor wouldn't hurt.


Winkelmann


----------



## christer W.

Talk about speedy replies! Don't you guys work?










In looking at my photos again, I can see your confusion. What you don't see is that I have a length of soffit running the full length of the left wall which houses HVAC vent and gas line. It starts out about 30" wide at the screen wall and grows to nearly 6' by the time it reaches the rear of the room as you can see here. You can also see how the riser has nowhere to go as far as re-positioning:











This gives you a better idea of the design issues I faced. In my previous shots, you can't see the entrance to the room. The white door in the shot above is to access HVAC and water heaters, not the entrance to the room. The shot below shows how the soffit and entrance (door with poster on it) affected the look of the room.











The screen is centered on the section of wall which has full ceiling height (8'). You can see a vertical seam that drops straight down from the soffit just to the right of the two electrical boxes in the corner in the picutre above. This section to the right is what the screen is centered on. The seating is centered in front of the screen. The speakers are in the corners. When you are in the room, if you really pay attention, you can tell the screen if offset to the right _relative to the speakers_ , but not to the wall/ceiling interface. If I had centered the screen on the wall, not the ceiling, the left section of the screen would be under the soffit. If I did that, apart from making the room look out of balance, it would also have meant having to extend the riser to the left (looking forward) to center the seating, blocking access to my furnaces and water heaters. I really did give this a lot of thought. Regarding the perceived problem of the speakers being offset to the screen, I think the visual imbalance of having one speaker in the corner and the other two feet in from the corner is too high a price to pay for the very nominal improvement in imaging I would experience, but I will give it a try! The center channel is centered under the screen which is centered relative to the seating. Since in a movie, all/most dialog comes out of the center, I think my problems in this area are not as great as you may think. The only thing off center is the left speaker.


Funny, when I got my Heresys back in the 70's Klipsch themselves counciled putting all their speakers in corners. You may have heard of Klipschorns? I have always had them in the corner of every room they have ever been in. Nothing else ever ocurred to me. I suppose I could move them forward and inward, slightly. With grandkids LEAPING on to the Lovesac (basically a giant beanbag you can see in the earlier post), the idea of having the speakers out in the room is not one that thrills me. As you get older, the idea of life being a series of compromises comes home, over and over!










The screen itself is a product of Mississippi Man's Mudd formula that was popular when I built this three years ago. A combination of silver metallic udercoat and top coats consisting of a mix of clear base, ultra pure white and pearl opalesence. At Home Depot, they thought I was crazy when I had them mix it up for me. I have since re-painted it so that it is still in the same space, but slightly wider, and slightly taller. It was 106", now up to 118" diagonal. The black frame is now butting up against the right wall, and the top molding is pretty close to the ceiling, so there isn't any way to get anything meaningful on either side. Bottom and left are what's available.


The chairs are indeed from IKEA. I paid 69.00 for the Poang chairs and 40.00 for the ottomans. You could spend far more for something far less comfortable, so I consider them a good buy. Also, their trim lines keeps the room 'spare' if you will. They are very comfy. I went to a friend's house who had his HT done professionally and watched a movie sitting in his Berklines. I didn't find them any more comfortable, and they had no head rest support.


Eugovector,


I really appreciate your input on the treatments. I doubt that I would have doubled up all the panels. Maybe I can get a discount now that I will have to buy twice as much or perhaps I will get the 2" stuff to start with.


----------



## cyberbri

I see. Didn't realize the room was wider in the back, or that there was a riser. But you said the screen now goes to the edge of the wall on the right.


No matter what, the screen and speakers should still ideally be symmetrical on the wall they reside, even with the soffit in the upper left corner. The screen area needs to be moved to the left, in the center of the wall (regardless of the soffit - move the screen down if needed).


Try putting on some 2-channel music, and play around with the location of the speakers. Even if they are close to the front wall, changing their proximity to the side walls will drastically change their sound. The point of side-wall absorption is to absorb the sound at the first reflection point. But with the speakers right next to the side walls, you are making that much worse than it should be. And you don't want to put a panel to the side of a speaker inches away from it.


----------



## christer W.

cyberbri,


Your suggestion means my seating will not be centered, or best case, the floor seats are centered, but the riser seats are off-set to the right.


In your gallery you have a picture of your daughter(?) kneeling on a bench/shelf. Next to her is an absorber shown wrapped in lilac. Is that mounted there full time? If so, I think we are coming from very different spaces in regards to how the balance of aesthetics vs sound performance needs to be addressed.


Don't get me wrong, and I am not criticizing, but I cannot imagine moving my screen down and to the left. The sight lines for the rear viewers, offest to the right in this new scenario would be like being in an old theater; they would have to look around the heads of the people in front of them to see the bottom of the screen. With my Heresys in place before I moved the screen up, the center was just flush with the bottom of frame. Moving it down at all would require either laying them on their sides, or making the screen narrow enough that the L&R would fit on either side and perhaps a different center channel. Neither of those sound good to me, no pun intended.


----------



## cyberbri

I just said "ideally." In the end, you have to do what works for you. Having speakers right next to the wall, and/or place asymmetrically, is very bad for the sound. If you only watch movies and don't listen to music in the room, that's probably not much of a concern for you. If you can find a way to treat the side walls and maybe the ceiling, that should help a lot, especially with the speakers so close to the side walls.


And no, the panels are not mounted or permanent. But they are there full-time. There's a window there, which is presumably even worse for reflections than a regular wall. We need the bench/shelf there, so putting the panel sideways on top of it worked the best. On the other side, the matching panel is sitting on the floor, propped against the wall.


So the balance of aesthetics vs sound for my living room is 45-55. If it was a dedicated room not used for anything but TV/movies/music/games, it would be 10-90 or 20-80, aesthetics vs sound. I would make sure everything (screen, speakers, seating) was centered and symmetrical and set everything up for the best sound and picture. Plus a lot more room treatments. I have done that as much as I can in my living room, to the extent that we have to have other furniture in the room because it functions as a living room as well, with a fireplace on the left and a large bay window on the right (and a desk w/computer in rear of room under R surround speaker). But I have kids (8yo and 2yo) and I still have my speakers out and not against the walls. They know not to touch or play around with them, and this is in our _living room_.


----------



## christer W.

When I get everything put together, I will post new shots and PM you and eugovector.


Thanks again for your input.


----------



## Winkelmann




christer W. said:


> Talk about speedy replies! Don't you guys work?
> 
> 
> 
> 
> 
> 
> 
> /QUOTE]
> 
> 
> Nope, I retired in 96'. Piddling around with construction projects, art and the like keeps me busy.


----------



## Felgar

Christer,


I think you've been given some very good advice and I agree with it for the most part. Normally with 3 seats in the front you want to keep the main center position just a bit (6-12") off dead-center but with only 2 in the front it'd be perfect to center the seats exactly. IMO the solution for you is to make the screen smaller. A large screen is not necessarily better. What's needed (IMO) is a screen that's large enough to see all of the detail presented in the image. Too close and/or large and you see imperfections that you're better off never seeing, and too small will have you missing details. I suspect even an 70-90" screen would be plenty but you could test this yourself by just projecting a smaller image for a bit and seeing how the PQ looks. Some of the benefits of a smaller screen is that it'll be brighter and will also look like a more clear, detailed image from any given distance compared to a larger screen.


What I'd like to stress is for you to try things out for yourself. For Sound Quality, get some good music that you know inside and out, and then listen to it with your speakers where they are, vs pulling them 2 feet out from the rear and 2 feet in from the side walls. Then you can hear the difference that pulling them off the side walls makes, and judge the tradeoff for yourself. The consensus is that even toed in towards the listenner, speakers should be at least 18" away from the sides and from the rear also. Being too close to the sides will affect the voices and highs, while being to close to the rear will affect bass and lower frequencies.


----------



## christer W.

Felgar,


Thanks for your reasoned response. I have been grateful of the advice given and will use it to the best advantage for my room.


Regarding the screen, what you may have missed is that I have made by screen BIGGER after having lived with the one you see in the pictures for near on 3 years, so this is not an impulsive newbie move. My earlier PJ was the Panasonic L200u that had/has 1/4 HD panels. On my 106" diagonal screen at 12", if I really looked hard, I could see a little SDE. So what? Still looked great. Still would have looked great if I had sprung for a new bulb. But, for only a little more, a 720p seemed like the way to go.


I went over to a fellow AVS'er who has a Panasonic L500 with 720p panels and the difference was very noticeable, this in spite of his projecting onto a 122" diagonal screenl. I was amazed at how those extra inches seemed to make such an impact. Had to go home and plan it all out. While I was at it, the idea of doing some sound treatments came to mind, which is how we all got here.


I am looking forward to making the panels. I am figuring about a dozen in various shapes, thicknesses,, and types. It should be fun and for not very much money.


----------



## eugovector

I'm with you on some level, as viewing distance is, IMO, the most overlooked aspect in our bigger is better world. However, Christer is right on THX spec w/ his screen/seating distance. As long as he's watching high-res material on good equipment, it'll look fine. In the end though, unless you have a acoustically transparent screen and have positioned speakers behind it, you'll likely be sacrificing acoustics for image size in THX spec.


The rule of thumb that I use is seating distance should equal 2 times the 16:9 screen diagonal. Now, THX specs will tell you that this is way to small. Check out this calculator here:

THX Seating Distance Calculator 


I currently sit 7.5 feet away from my 51" screen, a little closer than 2x the diagonal. THX tells me that I should either be sitting less than 6 feet away, or that I should have a 67" screen. But I won't bemoving closer, or buying a bigger TV, and this is why.


Let me start by saying that I'm throwing out approximate numbers here, just working off the back of a piece of scrap paper. I'm sure my math is a little off with rounding and what not, but close enough for our purposes.


Speaker placement: Dolby recommends front speaker placement 22-30 degrees off center. THX suggests similar placement. Many opinions that I've read say that for movies, you should shoot for the 22 degrees, for stereo music, the 30. Break out our 11th grade trig books and we see that the distance between speakers should be between 0.8 (for movies) and 1.15 (for music) of the seating distance.


My screen is about 45 inches wide, with the bezel my TV is 48. On my fronts (JBL S38II), the tweeters are atleast 14 inches from the side of the speaker. That means that if I butt the speakers right against the edge of my screen, the tweeters are 73" apart. Realistically, leaving an inch or two in between, we're at 75-77". At my THX recommended seating distance of 5.7 feet (68.4 inches), the tweeters of the speakers should be between 55 (movies) and 79 inches (music) apart. That doesn't leave a lot of wiggle room, and I found that in my room, the 79" was even too wide for music. I also needed a wider sweetspot, as I'd be watching most movies as at a pair, not a single.


So what did I do? Buy smaller speakers? Nah, I compromised. Good sound was more important to me than the biggest picture image (especially considering that I won't be watching HD exclusively, but also a lot of upscaled and processed 480P). I spent a lot of time listening, and moving, and listening, and measuring, and listening, and moving, and listening some more.


So, long story short, I postioned my speakers correctly and use a rule of thumb that you should sit slightly less than 2x the screen diagonal away from your display. No complaints yet.


Christer, with your current screen size, you'll probably be sacrificing acoustics for screen size. If that works for you, don't worry about it. Do what you can with your current setup, and sit back, and enjoy. However, if you want to improve your sound, positioning everything correctly is the start.




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> IMO the solution for you is to make the screen smaller. A large screen is not necessarily better.


----------



## christer W.

I plan on moving things around a little to see what sounds best. It should be interesting. Documenting all the changes will be the hardest part


----------



## christer W.

Getting ready to enlist some help from a family member to sit in the chairs while I wander around the room with a mirror to figure out where to place my yet-to-be-built panels/traps. Was thinking about the idea of putting an incandescent light where the speakers are to help you get your reflection points, as suggested elsewhere on this thread.


What exactly do you get out of seeing the bulb that you don't get out of seeing the speakers themselves in the mirror? I am guessing you are trying to make it easier to see??? Why not just have your assistant aim a flashlight at the speaker itself, if necessary? Place the center of the speaker in the middle of the mirror, attach piece of tape/Postit note on wall behind mirror to mark center of panel....


Is there something I am missing?


----------



## LewisCobb




> Quote:
> Originally Posted by *christer W.* /forum/post/0
> 
> 
> Getting ready to enlist some help from a family member to sit in the chairs while I wander around the room with a mirror to figure out where to place my yet-to-be-built panels/traps. Was thinking about the idea of putting an incandescent light where the speakers are to help you get your reflection points, as suggested elsewhere on this thread.
> 
> 
> What exactly do you get out of seeing the bulb that you don't get out of seeing the speakers themselves in the mirror? I am guessing you are trying to make it easier to see??? Why not just have your assistant aim a flashlight at the speaker itself, if necessary? Place the center of the speaker in the middle of the mirror, attach piece of tape/Postit note on wall behind mirror to mark center of panel....
> 
> 
> Is there something I am missing?



Hi Chris - The main thing is to see the speaker in the mirror at your seated position. Whether the speaker is lit up, there's a light bulb in place of it, or there's a small statue of Elvis where the speaker will be, should pose no difference in the outcome. There could be some unexpected trauma for the seated person suddenly seeing Elvis when he really should be working at the 7-11 across town, but that's not an acoustic issue and outside the scope of this discussion.....


----------



## Winkelmann

Going solo? Use a laser with the mirror method to find first reflection point.


----------



## christer W.

Ahh,


The laser. Hmm....something to use my pointer for other driving my cat crazy making her chase the red dot on the floor.


Not sure how the laser helps with going solo. Can you elaborate on this technique? Doesn't the mirror have to move back and forth until the person in the chair sees the speaker? I suppose if you had a large enough mirror, you eye-ball where you think it should appear, place the mirror there (hoping you have the correct vertical angle so your beam doesn't go right over or under the target) and then use the laser to pinpoint the location of the center of the panel....


----------



## BasementBob

christer W.


I'd use the laser for direct pointing your speakers, and not for the mirror trick.


The problem with the light bulb, is that you have to move your speaker to put it there. And it would only work if you walls were painted gloss so the light would reflect. Or for example if you have a plant in the way, it's not going to work.


You can calculate mathematically where the wall reflection point is (if your walls aren't square mathematically is a little trickier, and if they're curved use a mirror), or if you have a 3"x3" mirror and some post it notes, then you can sit and someone else can move the mirror along the wall until you can see the speaker in the mirror and then they can put a post it note there labeling the name of the speaker you can see. So each left/right wall should have three post it notes (left speaker, right speaker, center speaker) for each seating position. Then where you want first reflection point absorbers is a minimum 1' outside of all the post it notes.


The phrase you may recall from grade school is "angle of reflection equals angle of incidence". Sound is bouncing off that wall.


Later, if you do measurements with RTA software, the difference in time/distance (because sound travels at 1130ft/s, 1 foot is approximately 1ms) between the direct sound path length (e.g. 3'), and one of The Mirror Trick reflection sound path lengths (e.g. 13'), is the corresponding spike that appears in your impulse graph (e.g. 13' - 3' = 10', aka a spike that appears 10ms after the direct sound).

In this graph there's a spike at 29.9ms (direct sound), and another one at 31.1ms (reflection) and another one at 39.5ms (reflection).

31.1 - 29.9 = 1.2 feet. (approximately)

39.5 - 29.9 = 9.6 feet.

On a frequency response graph it appears as comb filter dips.


See the Direct vs Reflected macromedia flash at
http://www.acoustics.salford.ac.uk/a.../duck/duck.htm 

http://www.audioholics.com/news/uploads/slide02.gif 
http://www.audioholics.com/techtips/...reatments3.php 

http://www.msr-inc.com/sp_installation.php 

http://www.etfacoustic.com/mirrortrick.html 

http://www.bryston.ca/newsletters/43_files/vol4is3.html 

http://www.asc-hifi.com/acoustic_basics.htm 

http://www.auralex.com/auralex_acous...mirrortest.asp 

http://www.stjohngroup.com/downloads...EL_install.pdf (see page 2)

http://forum.studiotips.com/viewtopic.php?p=14288#14288 

look at "1st Ceiling Reflections.pdf", "1st Side Reflections.pdf"

http://www.audioholics.com/techtips/...ics101THX2.php 

http://psbg.emusician.com/ar/emusic_...ered_studio_2/ 

http://www.realtraps.com/art_room-setup1.gif 

http://www.realtraps.com/art_room-setup3.gif


----------



## christer W.

BasementBob,


Thanks for the links. Most interesting. I have now come upon something that has me even more slightly confused than before. The MSR site you suppled to a link to has a very complete installation guide to their products. What has me confused is this image and subsequent text:











My confusion stems from the advice given throughout this thread that the treatment of side walls should extend up to ear level, or a figure of 44"- 48" is seen often. The diagram is hard to make out, but their instructions are not:


"Fasten a V-Bar so the bottom of this bar is 64 inches from the floor onto the wall using either drywall screws into studs, using wallboard inserts and screws, or other appropriate fasteners."


You then hang the panel with its already attached V bar mate. In the diagram, you can see that their panels extend a couple of inches higher than the V bar, and they are off the floor about 18-24" - hard to tell exactly.


So which is it? Obviously, I can experiment, but am loath to put holes in my walls that may later need to be patched and painted


----------



## BasementBob

christer W:


Both are valid.


There are a bunch of different styles of applying acoustical treatment.


One is Dennis Erskine Style (i.e. copying the romours, not an actual DE designed theater which is almost certainly better).

Another is putting a bunch of 2'x4' panels, roughtly evenly spaced throughout the room.

There are others.


The only example of a bunch of 2'x4' panels, in a home theatre, that I have handy are these:
http://www.realtraps.com/cust_ht1.jpg 
http://www.realtraps.com/cust_ht2.jpg 
http://www.realtraps.com/cust_ht3.jpg 
http://www.realtraps.com/cust_ht4.jpg 
http://www.realtraps.com/cust_ht5.jpg 
http://www.realtraps.com/cust_ht6.jpg 


In a DE Style theatre, the rule is

a) front wall, floor to ceiling, wall to wall, 1" of linacoustic

b) side and rear walls, floor to half way up the wall, 1" of linacoustic. Assumption that the mirror point of all speaker drivers to all listener's ears is lower than the half way up the wall point.

c) side and rear walls, half way up the wall to ceiling, polyester batting

d) lots of leather covered couches (bass absorption)

e) rear riser and columns with bass traps (helmholtz, membrane)

f) deeper absorption (e.g. 6" 703 with 4" air gap behind) on some side/rear wall surfaces

g) carpet with thick underlay

h) soundproof rigid walls, preferably decoupled with something such as RSIC, and green glue to damp the wall resonance.


So, the absorption is used to do two things:

1) change the RT60 of the room so it's a little on the dead side

2) handle first reflections and SBIR issues.


Where the absorption is not, the idea is to let the sound reverb (bounce) around the room to increase ambiance and spaceousness, and reduce knowledge of directivity. Notice how the front 3 speakers have absorption on all sides, but the left/right/rear surround speakers have reflective surfaces near them (walls without absorption). Imagine the sound bouncing around above your head for many reflections.


What it sounds like where your ears are not, who cares.


An obvious side effect of treating the entire room's bottom half, is that it doesn't matter where the seats are placed, or where the listener sits, it's guranteed that first reflections are handled. No mirror trick is required.


If you're putting 2'x4' panels up, the mirror trick is required. If it's possible to spread them out with space between each, that's better (a diffusive and a LF absorptive effect) -- but for the main left/right reflection point in a home theatre with 3 or 4 front seats, and a second row, this is usually impossible.


So, in summary, you want to absorb the actual reflection. But you also want to have sound bounce around the room a bit. Both the designs/recommendations you spotted do that in different ways.


----------



## christer W.

BasmentBob,


Thanks very much for your concise distillation of the entire 64 page thread. Had I known to ask, I could have saved myself hours of reading.


I look forward to the the mirror exercise.


----------



## Ethan Winer

Chris,


> I look forward to the the mirror exercise


----------



## eugovector




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> christer W:
> 
> 
> Another is putting a bunch of 2'x4' panels, roughtly evenly spaced throughout the room.
> 
> There are others.
> 
> 
> The only example of a bunch of 2'x4' panels, in a home theatre, that I have handy are these:
> http://www.realtraps.com/cust_ht1.jpg
> http://www.realtraps.com/cust_ht2.jpg
> http://www.realtraps.com/cust_ht3.jpg
> http://www.realtraps.com/cust_ht4.jpg
> http://www.realtraps.com/cust_ht5.jpg
> http://www.realtraps.com/cust_ht6.jpg




If I'm not mistaken, that's Ethan's house. May not be your cup of tea, but probably sounds great.


----------



## longfellowfan

I have started a new thread on needing help with Acoustical Treatment with room dimentions and graphs. I did not where would be the best place to put it so Here is the link over to my thread in the audio theory section.


----------



## ad-man

Great reading. Thank you one and all for the primer. Now, lets talk specifics about ME! I am building a new room. I don't need to worry about sound bleed to other parts of the house. The room is approx.. 17' long and 15.5 wide. I treated under the drywall with a sound barrier material (about 5/8" thick soft fiber material recommended by the builder). At one end is screen. Screen is surrounded by a full wall cabinet. Two ends of cabinet are tall storage to ceiling. Screen is centered on room between two tall end cabinets (106" horiz.). Under screen across bottom is OPEN area of cabinet (fabric covered) where I plan to include center speaker and a sub (hidden away). Two front speakers sit 5' from front wall on carpet. Room has two levels, with first row of seats back about 11/12' and second row against back wall (17'). I will have a second, smaller sub in back of room to supplement bass. Here's my plan--

NO treatment for front wall (behind screen and cabinets). Use pre-made 1" thick fabric covered panels all around room, starting at chair-rail height and going up to ceiling. I want to find the best of both worlds for listening to 2-channel (hence no treatment on bottom 24" of all walls) and heavy treatment above 24". 2 side and 2 rear speakers are NOT dipole -- placed just above ear level. Ceiling has a 1' soffit all around (except front) but I was thinking about NOT treating that. I want to keep some liveliness to room because I am, at heart, a 2-channel guy struggling to get great sound from both HT and stereo. Am I completely off base???


----------



## cyberbri

Interesting article, rather technical, but good reading:
http://support.siasoft.com/Downloads...udy2/case2.pdf


----------



## ad-man

cyberbri, good info. Did you ever actually address these issues with specific tools/solutions? What was the outcome after solutions?


----------



## cyberbri

No, someone just posted it on a thread at hometheatershack.com. I'm on those forums mainly for REW/BFD stuff. I'm learning as well.


But I do have some room treatments (@ side wall 1st ref points, 1 behind center channel, and panels in front corners for bass traps), plus a BFD for my sub.


Treatments made a dramatic difference. I could elaborate...




Here's a few more good reads, although it's more fundamental stuff:
http://www.soundandvisionmag.com/ide...?topicID=28194 
http://www.soundandvisionmag.com/ide...?topicID=38945 



And another article:
http://www.prosoundweb.com/install/s...2/interact.php


----------



## ad-man

Thanks. I will review this.


----------



## eugovector

Be carefule putting your center channel in a bookshelf or other "box", it can dramatically affect the Sound Quality, and not in a good way.


I found wall treatment beneficial, even in 2 channel listening. With out reflections smearing and masking the sound, I started hearing instruments and background noises that I never heard before. If you want to keep the room live, treat the first reflection points only and keep the rest of the walls bare, but treat on as many of the 6 surfaces as you can.



> Quote:
> Originally Posted by *ad-man* /forum/post/0
> 
> 
> Great reading. Thank you one and all for the primer. Now, lets talk specifics about ME! I am building a new room. I don't need to worry about sound bleed to other parts of the house. The room is approx.. 17' long and 15.5 wide. I treated under the drywall with a sound barrier material (about 5/8" thick soft fiber material recommended by the builder). At one end is screen. Screen is surrounded by a full wall cabinet. Two ends of cabinet are tall storage to ceiling. Screen is centered on room between two tall end cabinets (106" horiz.). Under screen across bottom is OPEN area of cabinet (fabric covered) where I plan to include center speaker and a sub (hidden away). Two front speakers sit 5' from front wall on carpet. Room has two levels, with first row of seats back about 11/12' and second row against back wall (17'). I will have a second, smaller sub in back of room to supplement bass. Here's my plan--
> 
> NO treatment for front wall (behind screen and cabinets). Use pre-made 1" thick fabric covered panels all around room, starting at chair-rail height and going up to ceiling. I want to find the best of both worlds for listening to 2-channel (hence no treatment on bottom 24" of all walls) and heavy treatment above 24". 2 side and 2 rear speakers are NOT dipole -- placed just above ear level. Ceiling has a 1' soffit all around (except front) but I was thinking about NOT treating that. I want to keep some liveliness to room because I am, at heart, a 2-channel guy struggling to get great sound from both HT and stereo. Am I completely off base???


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Be carefule putting your center channel in a bookshelf or other "box", it can dramatically affect the Sound Quality, and not in a good way.
> 
> 
> I found wall treatment beneficial, even in 2 channel listening. With out reflections smearing and masking the sound, I started hearing instruments and background noises that I never heard before. If you want to keep the room live, treat the first reflection points only and keep the rest of the walls bare, but treat on as many of the 6 surfaces as you can.



I agree completely. We strive for timbre match of all speakers in a surround system, especially the LCRs. Placing one closer to a boundary - or in a "box" - will change it's sound.


My experience with adding absorbers at the first reflection points is that it made a dramatic difference in the clarity of everything, especially speech, and greatly improved mains/surround integration. The space behind my false wall is lined with 2" J-M Linacoustic, the front floor has a thick rug with the heaviest rubber pad I could find and the ceiling, front left & right walls and the _back wall_ have 2" OC SelectSound Black. So that I wouldn't use more absorption than I needed, I was very careful to cover only the area needed to do the job. BTW, the absorber that made the BIGGEST difference? Rear wall.


----------



## Ethan Winer




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> If I'm not mistaken, that's Ethan's house. May not be your cup of tea, but probably sounds great.



Yes, it's my home and it sounds excellent. Hey, what's wrong with acoustic panels hanging all over the place?!










If audiophiles will accept huge tower speakers with a pile of gear in the middle of the floor, all on pedestals and with cable elevators holding up speaker wire as thick as garden hose, then why not 40 bass traps?










--Ethan


----------



## cyberbri

I put a bunch of new pictures of my home theater and treatments (GIK Acoustics) in a new gallery (see signature). I don't have a ton, but I do have enough to make a big, noticeable difference. I have bass traps in the front corners and absorber panels on the left/right sides at the first reflection points, with a panel behind the center speaker.


----------



## Felgar

cyberbri, have you considered a helmholtz resonator at 95 Hz to try to do something about that null? Or is that not a concern for you?


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Yes, it's my home and it sounds excellent. Hey, what's wrong with acoustic panels hanging all over the place?!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If audiophiles will accept huge tower speakers with a pile of gear in the middle of the floor, all on pedestals and with cable elevators holding up speaker wire as thick as garden hose, then why not 40 bass traps?



Ummm . . . our wives?


----------



## cyberbri




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> cyberbri, have you considered a helmholtz resonator at 95 Hz to try to do something about that null? Or is that not a concern for you?




I haven't thought about it much. That dip/null appeared when I recently moved my speakers to their new location - it wasn't there with the speakers at their previous location. I'd have to run some 0/180 degree phase sweeps again, but assuming it's due to interaction between sub and speakers, I plan on adding some more bass traps in the future anyway. I am hoping to build some wedges to go behind the current corner panels. Hopefully that will fix or at least alleviate that drop.


----------



## pepar




> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> I haven't thought about it much. That dip/null appeared when I recently moved my speakers to their new location - it wasn't there with the speakers at their previous location. I'd have to run some 0/180 degree phase sweeps again, but assuming it's due to interaction between sub and speakers, I plan on adding some more bass traps in the future anyway. I am hoping to build some wedges to go behind the current corner panels. Hopefully that will fix or at least alleviate that drop.



If you're crossed at 80Hz, then the subs are probably not involved in producing such a steep/deep null.


----------



## cyberbri

I'll have to run some 0/180 phase sweeps again. But I think, at least in my situation, changing the phase had a large effect on the 80~160Hz range.


----------



## Felgar

That's cool cyberbri. I'm no expert but I interpretted those results as possibly needing a resonator, and was wondering if you'd tried it and what success you'd had. I'll be interested to see what your further efforts yield...


----------



## eugovector




> Quote:
> Originally Posted by *cyberbri* /forum/post/0
> 
> 
> I'll have to run some 0/180 phase sweeps again. But I think, at least in my situation, changing the phase had a large effect on the 80~160Hz range.



I think moving the speakers might be a much more effective and less costly solution than more bass traps.


----------



## cyberbri




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> I think moving the speakers might be a much more effective and less costly solution than more bass traps.




Before I had them in an equilateral triangle, spread pretty far apart. Then I used the formula provided by Ascend to reposition them (340SEs), which tightened up the already tight center stage - and the sweet spot on the couch is wider now too. I can experiment a little more with placement, but imaging and soundstage are more important overall to me than a narrow null there.



Actually, I went back and looked at my old graphs. I had them up on the HSU Research forum. These show the response of the sub in its current location, combined with the left/right mains in the previous location (equilateral triangle):
http://forum.hsuresearch.com/showpos...9&postcount=10 


You can see the dip/null in the "crossover disengaged" graphs. The 0/180 degree phase interaction at 60-80Hz and 100-200Hz is interesting to watch.



Phase = 0, Sub Crossover Engaged (max 80 or 90Hz):











Phase = 180, Sub Crossover Engaged (max 80 or 90Hz):












Phase = 0, Sub Crossover disabled (playing full signal):











Phase = 180, Sub Crossover disabled (playing full signal):


----------



## wgilpin

Howdy Y'all,


I wasn't satisfied with anything I saw commercially available, so a few months ago I bought a bunch of 8lb rock wool insulation to treat my room. Until now, it's just been leaning up against the walls in the theater, doing a fine job making the room sound good, and look awful.


I finally got going on doing something about it, and today I finished building my first panel absorber. I'll make 4 more to hang between each of my poster frames, then tackle the problem of dressing up the 4" thick corner pieces.


Eventually the wall and ceiling will be painted more appropriate colors, but that'll be no problem since the panel is hung on cleats. Easy on, easy off!


The vitals:


84" x 25.5" x 2.25" hardwood frame (stained & oil-rubbed)

Open back, spaced 1.75" from the wall

GoM Black fabric on the front

8lb 2" thick rock wool insulation

More pics here. 


Thoughts?


Thanks to everyone who posted information about room treatment, sound absorbent materials and GoM fabric! This forum is an inspiring place.


Cheers,


----------



## causeofhim

They look great!


----------



## longfellowfan

Wes those are sweet. I am going to make some panels in a few months and I never thought of staining the frames that was brilliant. And my wife saw it and fell in love with the idea.


----------



## bpape

Nicely done. I like that color combo of the cloth and stain.


Bryan


----------



## eugovector




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> 
> The vitals:
> 
> 
> 84" x 25.5" x 2.25" hardwood frame (stained & oil-rubbed)
> 
> Open back, spaced 1.75" from the wall
> 
> GoM Black fabric on the front
> 
> 8lb 2" thick rock wool insulation



Looks great. Where did you get the rockwool? How much was it? I'm assuming it's stiff like 703, or atleast stiff enough to stay in the frame with only your two braces?


----------



## causeofhim

I asked a similar question about rockwool vs. 703 in this thread:
http://www.avsforum.com/avs-vb/showthread.php?t=794904


----------



## wgilpin

Thanks for all the compliments y'all!



> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Looks great. Where did you get the rockwool? How much was it? I'm assuming it's stiff like 703, or atleast stiff enough to stay in the frame with only your two braces?



I bought the rock wool from SPI (Specialty Products & Insulation) here in Austin. They had the 4" thickness in stock, but I had to order the 2". Still, it was MUCH less expensive than similar OC products. I got 8 4" batts and 12 2" batts for approx. $150.


8lb rock wool is denser than OC703 or OC705. That's part of the reason I chose it. It's relatively stiff, and will stand up on its own. In fact, the 4" pieces will stack vertically without the bottom one collapsing. You can see a couple of the remaining 2" pieces leaning up against the wall in one of my pictures.


The two braces you're seeing don't actually touch the insulation. They're the cleats that the frame hangs on, and are attached at the ends of the spacers.


The frame is 1/4" deeper than the insulation, so there's room for me to staple in some retainers behind the batt if I need to. However, the pieces that are in this first panel are just friction-fit. The frame ended up a little bit tighter than I wanted it to be, so the insulation is in there quite snugly and won't be going anywhere. I'll build the rest of them 1/8" wider so the fit is looser.


Cheers,


----------



## eugovector

Wow, that sounds like an amazing price. I bought 12 4'x2' of OC 703 for $120 and thought I was getting a deal. I take it these pieces were 4'x2'?


Any concerns about the fibers getting into the air from the back?



> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> Thanks for all the compliments y'all!
> 
> 
> 
> I bought the rock wool from SPI (Specialty Products & Insulation) here in Austin. They had the 4" thickness in stock, but I had to order the 2". Still, it was MUCH less expensive than similar OC products. I got 8 4" batts and 12 2" batts for approx. $150.
> 
> 
> 8lb rock wool is denser than OC703 or OC705. That's part of the reason I chose it. It's relatively stiff, and will stand up on its own. In fact, the 4" pieces will stack vertically without the bottom one collapsing. You can see a couple of the remaining 2" pieces leaning up against the wall in one of my pictures.
> 
> 
> The two braces you're seeing don't actually touch the insulation. They're the cleats that the frame hangs on, and are attached at the ends of the spacers.
> 
> 
> The frame is 1/4" deeper than the insulation, so there's room for me to staple in some retainers behind the batt if I need to. However, the pieces that are in this first panel are just friction-fit. The frame ended up a little bit tighter than I wanted it to be, so the insulation is in there quite snugly and won't be going anywhere. I'll build the rest of them 1/8" wider so the fit is looser.
> 
> 
> Cheers,


----------



## wgilpin




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Wow, that sounds like an amazing price. I bought 12 4'x2' of OC 703 for $120 and thought I was getting a deal. I take it these pieces were 4'x2'?
> 
> 
> Any concerns about the fibers getting into the air from the back?



Yes, they're 24" x 48" batts. The rockwool I have is not Owens Corning brand. I *think* it's Roxul brand. SPIs price on OC was much higher than what I got, but after checking the acoustic performance numbers for the rockwool, I decided that it would do just fine for me.


I'm not too terribly concerned about the fibers from the back. Unless someone reaches back there and pokes at the insulation, it should be stable and not just spontaneously throw off fibers at random. If I'm ever convinced that it's an issue, I can just staple some of my left-over GoM scraps in the back, since the frame is deeper than the insulation.


Cheers,


----------



## colonelsnow

I have heavy velvet curtains on both sides of my screen. Is there a reason to put Insul-Shield on the front wall behind the curtains?


----------



## eugovector




> Quote:
> Originally Posted by *colonelsnow* /forum/post/0
> 
> 
> I have heavy velvet curtains on both sides of my screen. Is there a reason to put Insul-Shield on the front wall behind the curtains?



If the curtains are acoustically transparent, yes. Odds are they're not, so no, not really. In theory, you could put ~4" panels behind to absorb bass, but you'd probably be better going with corner placeet on those anyway.


----------



## Felgar




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> I finally got going on doing something about it, and today I finished building my first panel absorber. I'll make 4 more to hang between each of my poster frames, then tackle the problem of dressing up the 4" thick corner pieces.



They look great. One thing I couldn't tell from the pics is how you fastenned the GOM to the frame. It looks like it's attached to the inner side wall but I couldn't see how you did that while making the GOM flush with the front and pulled nice and smooth. It surely isn't just stapled, right?


----------



## wgilpin




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> They look great. One thing I couldn't tell from the pics is how you fastenned the GOM to the frame. It looks like it's attached to the inner side wall but I couldn't see how you did that while making the GOM flush with the front and pulled nice and smooth. It surely isn't just stapled, right?



Good catch! No, it's not just stapled.


I wanted to avoid the pillow-like look that would result from just stapling the fabric to the inside of the frame. I needed a sharp, crisp corner, but it was also important to me that the nice wood frame remain a visible part of the design.


I figured that the best way to do this would be to sandwich the fabric between the frame and a thin strip of wood around the inside perimeter of the frame. However, I didn't want the strip to leave a "step" on the the inside of the frame. Such a step would get in the way of installing the insulation. So, I made a rabbet in the inside-front edge of the frame to allow the fabric and the retaining strip to be stapled flush with the inside of the frame.


I've attached an image that shows the inside of the frame after the upholstery is stapled and trimmed. You can see the strip stapled into the rabbet, with the fabric sandwiched in between.


Maybe a little bit of overkill, but the results are worth it, IMO.


Cheers,


----------



## Felgar




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> I've attached an image that shows the inside of the frame after the upholstery is stapled and trimmed. You can see the strip stapled into the rabbet, with the fabric sandwiched in between.
> 
> 
> Maybe a little bit of overkill, but the results are worth it, IMO.



Thanks for the extra description. Going back I can see the rabbet is just barely visible in some of the pictures of the frame also. Excellent work, and I agree that the results are most certainly worth it.


----------



## longfellowfan

Wgilpin,

What did you use to fasten your panels to your wall. I am going to make some diy panels this weekend or next.


----------



## wgilpin




> Quote:
> Originally Posted by *longfellowfan* /forum/post/0
> 
> 
> Wgilpin,
> 
> What did you use to fasten your panels to your wall. I am going to make some diy panels this weekend or next.



I used french cleats. They're easy to make and even easier to use. Just rip a board with the saw blade set at 45 degrees. Trim one piece about an inch shorter. Attach the longer part to the frame with the cut pointing down, and the shorter part to the wall with the cut pointing up.


In my case, I used the cleat as a horizontal support as well, spanning the width of the frame between the spacers. Since I didn't want any visible fasteners, I used dowels to attach the cleats to the spacer blocks.


If you look at the attached picture you can see the cleat in action. The top part that's attached to the frame is stained, and the part screwed to the wall is not, so the parts and how they mate is easy to see.


Cheers,


----------



## Dominic S

Hi All:


Please for give me if these questions have already been asked and answered. There is tons of info in this thread. I intend on fabricating some acoustic panels for the first reflection points for my 12'x16'x10 listening/theater room.


From what I've been seeing on the board many of the DIY'ers use Owens Corning 703 semi ridged fiberglass insulation in the construction of their panels. Where have you been able to buy this stuff? I've tried Lows, Home Depot, & Menards no joy. It looks like the OC 703 and 705 are readily available from on line retailers but I'd like to avoid the shipping cost. Plus I enjoy making that extra trip back to the store after realizing that I forgot to buy something for a project.










Also, while doing some research on the Owens Corning website I found a product called SelectSound Black Acoustic Fiber glass. From the spec sheet it comes in one or two inch thick, 4'x8' sheets. Is anyone familiar with this product? Would this be better for making bass traps?


----------



## longfellowfan

If you call Owens Corning's 1-800 # they will tell you places that locally carry a particular product.

I called them and they directed me to a place locally (in St. Louis) that carry it and it was 703 2" thick 2'x'4' for 10.75 a sheet no min. order.


----------



## MarkMac




> Quote:
> Originally Posted by *Dominic S* /forum/post/0
> 
> 
> Where have you been able to buy this stuff?



I see you're in Milwaukee. You may want to try SPI...
http://www.spi-co.com/servicecenterdirectory.cfm 


The location in Lake Bluff, IL is probably ~an hour from you. I got very good prices from them, and they were able to get the material I needed within about a week.


----------



## cyberbri

I've seen it on eBay in cases, and here in cases:
http://sensiblesoundsolutions.com/pr...products_id=29


----------



## Bobkbusch

I'm planning on trying some Superchunk style corner bass traps. It seems the Roxul RHT 40 semi-rigid boards at 3.5 pcf are close to OC 703 at 3 pcf.


Any recommendations regarding this particular density vs. more or less dense mineral wool for a corner bass trap in the Superchunk style?


----------



## Habs4life




> Quote:
> Originally Posted by *Bobkbusch* /forum/post/0
> 
> 
> I'm planning on trying some Superchunk style corner bass traps. It seems the Roxul RHT 40 semi-rigid boards at 3.5 pcf are close to OC 703 at 3 pcf.
> 
> 
> Any recommendations regarding this particular density vs. more or less dense mineral wool for a corner bass trap in the Superchunk style?


 http://www.hometheatershack.com/foru...-traps-eq.html 

http://www.hometheatershack.com/foru...ht-layout.html 


Here are a couple of informative threads regarding corner traps that may help.







.


----------



## Bobkbusch




> Quote:
> Originally Posted by *Habs4life* /forum/post/0
> 
> http://www.hometheatershack.com/foru...-traps-eq.html
> 
> http://www.hometheatershack.com/foru...ht-layout.html
> 
> 
> Here are a couple of informative threads regarding corner traps that may help.
> 
> 
> 
> 
> 
> 
> 
> .



Thanks!!! Those are excellent threads. They lead me to this thread which also helped.

http://www.hometheatershack.com/foru...ass-traps.html 


Looks like my answer is to stay with the lower density 3.5 pcf mineral wool!


----------



## Dominic S

First thanks for all of you responses to my inquiry.


The fine peeps at SPI (Lake Bluff Ill) were able to point me in the direction of a retailer in the MKE area. If you need to contact them there info is as follows.


Lake Bluff, IL

1301 Laura Lane

Lake Bluff, Illinois 60044

847-362-0925

847-362-7889 FAX
http://www.spi-co.com/servicecenterdirectory.cfm 


For anyone looking in Milwaukee or Madison check out.


Acoustech Supply Inc

1710 South 106th Street

Milwaukee, WI 53214
http://www.acoustechsupply.com/ 


Both of these vendors are very helpful and do have OC703 & 705 available at very reasonable prices. You must purchase a full carton of either though.


703 2 comes 12ea 2'x 4' sheets to a carton. $1.30 sq/ft

705 1 comes 10ea 2' x4' sheets to a carton. .60 sq/ft


Dom


----------



## Bobkbusch

I was at a local JoAnn's Fabrics store today and came across some nice synthetic suede material. I'm considering it to cover the 1" thick Linacoustic panels I'll be putting up on my side and rear walls. Trouble is, it didn't pass the "blow through" test.


I noticed SoundSuede at AcousticalSolutions.com and SonoSuede at Auralex.


I'm guessing they are similar to what I saw at JoAnn's, but perhaps they are more "acoustically transparent."


Anybody having experience using this type of fabric to cover panels for first reflections care to comment on how well it works and whether SoundSuede or SonoSuede passes the "blow through" test?


----------



## christer W.

I was having a hard time finding OC703 here in Salt Lake, but did find a source for both Knauf and Johns-Manville who make similar products with similar acoustic properties. the J-M was slightly less money for 2" - 1.40/ft compared to 1.75 for the Knauf, so I was all set to go. When I got there, a very helpful guy asked me what I was doing with this stuff, so I told him and he suggested Rockwool. Said a local HT installer bought tons of it all the time. Same size panels - 2X4', 6 pcf, slightly better performance on paper, and barely half the cost.


I bought black burlap at JoaAnn's for 2.99/yd. They thought I was nuts when I told them I wanted 15 yards! The burlap was a bit of a mess to work with (leaves a lot of broken fibers on the table you are working with, but it does look good. No sheen to it, and it has a nice texture.


I faced the panels with 1/2" poly batting to give the panel surface some 'spring'. Spray adhesive to attach the batting to the panels. Hot glue to fasten the fabric over the batting onto the back of the Rockwool. It would be a stretch to say they have a lot of structural strength, but all they have to do is look good. Doing it again, I would frame the Rockwool to give me something solid to work with for mounting. If you go here , you can find pre-cut artist frames for making canvases for painting. The come in all sizes, require no tools other than a mallet to pound the corners together, and are pretty cheap when you consider you can put together a rock-solid frame in a matter of a couple of minutes without creating a ton of sawdust. A 2X4' panel frame would run you less than $10. Interesting, anyway.


I tried using Velcro to attach them to the walls, but the Rockwool panels (and OC too, I suspect) just don't have enough density for the Velcro adhesive to grip onto. Probably wind up using hot glue to fasten a couple of relatively large (6"x6") piece of thin board to the panel that I can then either screw eye hooks into, use Velcro though kind of pricey, or the 45 degree miter cut board trick.


Pretty happy with the results. Dialog is more distinct, sound overall is more precise. Subtle, though. Perhaps more panels?


----------



## pepar




> Quote:
> Originally Posted by *christer W.* /forum/post/0
> 
> 
> Pretty happy with the results. Dialog is more distinct, sound overall is more precise. Subtle, though. Perhaps more panels?



If I've missed it, I apologize - did you "do" the ceiling and _back_ wall?


----------



## hardax

Hi all.


Got a question about treating my first reflection point.


Quick diagram attached to show you what I mean below.


I purchased some acoustical panels from GIK (fantastic company to deal with BTW).


I have a panel at my first reflection point (Red).


I have an extra panel and am wondering if I need to put it in the green area?


Since that far wall is over 18' away and partially blocked by the stairwell walls I am not sure if it would do any good there? My screen and speakers are blocked by the right hand side (stairwell walls) so wouldn't all the reflections just happen there?


Bryan? (sorry I lost your e-mail address) any comments?


Thanks for any suggestions


Edit: fixed the link. Sorry about that. Any ideas all?


----------



## christer W.

Pepar,


I did three panels under the screen measuring 17" high by 36" long, covering most of the lower portion of the screenwall. I may place a couple of smaller panels to the left of the screen above the lower panel in some sort of decorative pattern. Need to resolve the mounting solution first.


I also placed two 24"x48" panels on their sides along the back wall just above the riser. This spans most of the width of the riser Ear height for the two front seats is about 36", so this puts the rear panels at that height. There are seldom viewers in the rear row, so it is not of consequence. I have considered using the remaining three 7"x48" strips as some sort of corner trap where the rear wall meets the ceiling at the rear of the riser.


I put panels coming out of each corner flanking the screen, as well as another at the first refelction point, all 36" high. The left panel could be moved and replaced with corner trap. No such option on the right side. So, a total of 8, all 2" thick. I did not put a panel on the ceiling.


My overall sense is that it is a good start, but for not a lot more dough, I could add another half dozen panels here and there. One of the problems I ran into when I did the mirror trick was that there always seemed to be something in the way where I wanted to place a marker for a panel. Like a door, or electrical outlets, or speaker hookups. Thought I had planned it all out.










Given the relative incremental improvement in sound, not sure how far I want to go with this experiment. I like my rooms to have clean lines with spare furnishings, so am not too gung-ho about filling this room with panels on every surface. May need to find a different color to provide some contrast to the heaviness of the black.


I will get some shots taken this week.


----------



## eugovector

I'd say that you should be getting very significant changes, unless things are positioned wrong.


What do I mean by significant?

1) My Girlfriend noticed the dialogue being easier to understand.

2) Her friend who still watches his 37" LCD with a composite cable connecting the DVD player, and listens through the built in speakers, made an unsolicited comment about how the room didn't sound "like a small livingroom. It's creepy actually"


I have 9 2'x4' panels up in a 14x15 room, so t be 10 if I get around to covering the final one this weekend.



> Quote:
> Originally Posted by *christer W.* /forum/post/0
> 
> 
> Pepar,
> 
> 
> I did three panels under the screen measuring 17" high by 36" long, covering most of the lower portion of the screenwall. I may place a couple of smaller panels to the left of the screen above the lower panel in some sort of decorative pattern. Need to resolve the mounting solution first.
> 
> 
> I also placed two 24"x48" panels on their sides along the back wall just above the riser. This spans most of the width of the riser Ear height for the two front seats is about 36", so this puts the rear panels at that height. There are seldom viewers in the rear row, so it is not of consequence. I have considered using the remaining three 7"x48" strips as some sort of corner trap where the rear wall meets the ceiling at the rear of the riser.
> 
> 
> I put panels coming out of each corner flanking the screen, as well as another at the first refelction point, all 36" high. The left panel could be moved and replaced with corner trap. No such option on the right side. So, a total of 8, all 2" thick. I did not put a panel on the ceiling.
> 
> 
> My overall sense is that it is a good start, but for not a lot more dough, I could add another half dozen panels here and there. One of the problems I ran into when I did the mirror trick was that there always seemed to be something in the way where I wanted to place a marker for a panel. Like a door, or electrical outlets, or speaker hookups. Thought I had planned it all out.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Given the relative incremental improvement in sound, not sure how far I want to go with this experiment. I like my rooms to have clean lines with spare furnishings, so am not too gung-ho about filling this room with panels on every surface. May need to find a different color to provide some contrast to the heaviness of the black.
> 
> 
> I will get some shots taken this week.


----------



## christer W.

I didn't say it wasn't significant, only that from this point forward, the improvement would be incremental. I would say the room is still 'lively', but 'better' than it was. Not my goal. Dialog is more distinct, staging is more precise. Clearly, if I put enough Rockwool in there, I could smother all the highs and create a 'dead' room. As I did not take any measurements (not that I know how to do that anyway), it is all gut feel.


Still, for only $125, it has been a fun experiment. Just have to figure out a good way to fasten them to the walls and move on to the next project - bigger screeen, and then on to the next: rope light in a crown molding trough up near the ceiling. Good excuse to buy a compressor/nailer.


----------



## pepar




> Quote:
> Originally Posted by *christer W.* /forum/post/0
> 
> 
> I didn't say it wasn't significant, only that from this point forward, the improvement would be incremental. I would say the room is still 'lively', but 'better' than it was. Not my goal. Dialog is more distinct, staging is more precise. Clearly, if I put enough Rockwool in there, I could smother all the highs and create a 'dead' room. As I did not take any measurements (not that I know how to do that anyway), it is all gut feel.
> 
> 
> Still, for only $125, it has been a fun experiment. Just have to figure out a good way to fasten them to the walls and move on to the next project - bigger screeen, and then on to the next: rope light in a crown molding trough up near the ceiling. Good excuse to buy a compressor/nailer.



The biggest improvements in my room were made by placing absorbers at the first reflection points that produce delayed sound at 0° and 180°, i.e. the front wall (behind the LCR spkrs), the ceiling and the rear wall. I "think" the left and right front wall panels made a difference as well, but no where near as much as the ones I just mentioned. Beyond the FRP panels, I would only use additional absorption if the acoustics of the room needed it.


----------



## christer W.

I realize in my previous post that there is a line out of place. My phrase "Not my goal" was meant to go AFTER my assertion that I could load the room up with Rockwool and make the room dead.


I think the rear wall will get more attention next. The front wall just doesn't have the real estate to work with.


Without frames, these panels that are 2'x4' weigh about 8-9 lbs. I wonder if I couldn't do a picture hanger method. IOW's secure two anchors to the back of the panel with a wire across and a nail-syle hanger in the wall. Don't like punching holes in the wall unless I have to.


Pepar,


Where did you put your panels in the ceiling relative to your speaker placement and seating position? I am sitting about 12' from the back. Ceilings are 8'. speakers are flanking the screen with the center in the center.


----------



## pepar




> Quote:
> Originally Posted by *christer W.* /forum/post/0
> 
> 
> pepar, where did you put your panels in the ceiling relative to your speaker placement and seating position? I am sitting about 12' from the back. Ceilings are 8'. speakers are flanking the screen with the center in the center.



Tip: Forget about the mirror trick. Think pool and bank shots. Angle of incidence = angle of reflection. Stand to the side and look at a front speaker and the seating positions. Visualize a line from the speaker to a seat bouncing off the ceiling in between "leaving" at the same angle that it "arrived." Repeat for all front speakers and all seating positions and cover the "bounce points."


I was able to cover three speakers to six seating positions with a panelized 4x8 sheet of OC SelectSound Black. You can click on the link in my sig and see the whole process documented.


----------



## vfrjim

First(or early reflection) points question. Do Dipole front speakers have a first reflection point like a typical box-type speaker? Specifically a Magenpan panel type speaker. Do they need to be treated differently?


----------



## pepar




> Quote:
> Originally Posted by *vfrjim* /forum/post/0
> 
> 
> First(or early reflection) points question. Do Dipole front speakers have a first reflection point like a typical box-type speaker? Specifically a Magenpan panel type speaker. Do they need to be treated differently?



Oh man, dipole fronts certainly complicate things, but yes. Obviously, you wouldn't be treating the first reflection point _behind_ the speaker, but all of the others, especially floor, ceiling and rear wall would benefit from proper treatment.


----------



## Speedskater

For more (much more) on dipole's and dipole placement see the Linkwitz Lab.
http://www.linkwitzlab.com/


----------



## pepar




> Quote:
> Originally Posted by *Kevin Graf* /forum/post/0
> 
> 
> For more (much more) on dipole's and dipole placement see the Linkwitz Lab.
> http://www.linkwitzlab.com/



And probably MUCH more than he needs - or has time - to read. If he's going to get anything usable at all from that site, he should probably start with the room acoustics section.


----------



## vfrjim




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Oh man, dipole fronts certainly complicate things, but yes. Obviously, you wouldn't be treating the first reflection point _behind_ the speaker, but all of the others, especially floor, ceiling and rear wall would benefit from proper treatment.




Technically, I would be treating that point with bass traps in the corner, would that have a detrimental effect on the dipoles?


----------



## pepar




> Quote:
> Originally Posted by *vfrjim* /forum/post/0
> 
> 
> Technically, I would be treating that point with bass traps in the corner, would that have a detrimental effect on the dipoles?



The point behind the dipoles would get traps? Wouldn't that suck out the highs along with the lows?


----------



## vfrjim




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> The point behind the dipoles would get traps? Wouldn't that suck out the highs along with the lows?




How would you deal with bass traps in the corners then? I'm all ears.


----------



## pepar




> Quote:
> Originally Posted by *vfrjim* /forum/post/0
> 
> 
> How would you deal with bass traps in the corners then? I'm all ears.



Well, there are more "corners" in a room than the vertical ones at front left and front right where the L&R mains are located.


----------



## eugovector




> Quote:
> Originally Posted by *vfrjim* /forum/post/0
> 
> 
> How would you deal with bass traps in the corners then? I'm all ears.



And you can always go with FRK 703 foil side out. Highs will reflect off, and it's actually better at absorbing low Freqs according to Bob Gold.


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> And you can always go with FRK 703 foil side out. Highs will reflect off, and it's actually better at absorbing low Freqs according to Bob Gold.



Wouldn't it just be better to avoid any treatments around the dipoles?


----------



## eugovector




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Wouldn't it just be better to avoid any treatments around the dipoles?



No, I agree. I'm just offering options. His room setup and sense of asthetics may not allow him to adequately treat the room otherwise, and if he doesn't like the sound of FRK, simply peal the foil off, and you've got the makings of a broadband panel that can go elsewhere in the room. It can't hurt to try.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Wouldn't it just be better to avoid any treatments around the dipoles?



Maybe I can clarify something.










The fact that dipole speakers radiate equally front and rear is a _byproduct_ of their design, not necessarily a design goal. Sort of like a figure 8 microphone. It is what it is. This does not mean the rear radiation is a good thing. IMO it is not because it guarantees you'll have SBIR peaks and nulls up into the higher frequencies, not just at bass frequencies as with typical box loudspeakers.


If it were me I'd put a fair amount of absorption on the front wall behind the speakers. In fact, this is one of the few cases where I think front wall absorption is really necessary.


--Ethan


----------



## Felgar

So then you disagree with many of the conclusions of that Linkwitz lab Room Accoustic site posted a few days back Ethan? Some of the arguments showing the level of ambient noise vs. sound directly from the speaker I felt were very convicing. Since I've spent 20K+ on monopoles I'm not about to switch, but if you shared your thoughts about that topic it might make me feel a bit better.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> The fact that dipole speakers radiate equally front and rear is a _byproduct_ of their design, not necessarily a design goal. Sort of like a figure 8 microphone. It is what it is. This does not mean the rear radiation is a good thing. IMO it is not because it guarantees you'll have SBIR peaks and nulls up into the higher frequencies, not just at bass frequencies as with typical box loudspeakers.



I'm not so sure it's a byproduct. I'm more sure that it's the way the designer wants them. Which is why I haven't liked anything other than front radiators including Amar Bose's claim to fame. Sorry, not looking to flame or get flamed; it's just my personal taste.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Maybe I can clarify something.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The fact that dipole speakers radiate equally front and rear is a _byproduct_ of their design, not necessarily a design goal. Sort of like a figure 8 microphone. It is what it is. This does not mean the rear radiation is a good thing. IMO it is not because it guarantees you'll have SBIR peaks and nulls up into the higher frequencies, not just at bass frequencies as with typical box loudspeakers.
> 
> 
> If it were me I'd put a fair amount of absorption on the front wall behind the speakers. In fact, this is one of the few cases where I think front wall absorption is really necessary.
> 
> 
> --Ethan



I am not so sure that's the case. The rear radiation does contribute considerably to the overall sound field resulting in a difference in how the sound pressure falls off with distance. In my experience with Apogee full range dipoles, putting absorbtion across the front wall (behind the speakers) made them sound closed in and undynamic. Diffusion worked well.


----------



## pepar

If two speaker systems sound different, at least one of them is wrong. If that isn't controversial, the rest of it might be: And probably both are wrong.


If we are to be transported to the "environment" created by the artist/producer/enginer, the room needs to be REMOVED from the equation. Dipoles depend mightily on the room.


----------



## BasementBob

Dipoles are intended to create non-localizable sound. They do this two ways, firstly they are out of phase so the direct sound from the speaker is not localizable, and secondly they bounce the sound off multiple walls enhancing the effect. This is optimal for movie background sounds such as music, raindrops, crouds, and traffic noise -- which are often delivered through the side and rear surround speakers, taking advantage of this intended and expected effect.


Personally I watch a lot of action movies, so I prefer monopoles for my side surrounds, giving me more directionality than is recommended by THX. This is optimal for sounds like bullets and jets flying overhead from front to back. I bought surrounds with a monopole/dipole switch in them, and I've tried both settings.


IMO, buying dipole surround speakers, and then absorbing the front and rear walls (or side walls for rear dipoles in a 7.1 system), is probably silly. Diffusion on the other hand is probably a good idea. You may have noticed that in DE Style theatres, the side and rear walls do not have absorption above the ear level, and that's where the dipole speakers go -- far away from absorption at their level, to maximize bouncing of that sound around the room, increasing ambience.


Dipole front speakers would be odd. I can't see a point in those. Since localization is required for imaging, and there's lots of intended and required L/R imaging in the front speakers in movies.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Dipole front speakers would be odd. I can't see a point in those. Since localization is required for imaging, and there's lots of intended and required L/R imaging in the front speakers in movies.



BINGO!


----------



## Kal Rubinson




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Dipole front speakers would be odd. I can't see a point in those. Since localization is required for imaging, and there's lots of intended and required L/R imaging in the front speakers in movies.



Good point. They rely more on room acoustics for their soundstage presentation than do monopoles. Of course, such soundstaging is artificial and particular to each room. I used to have dipole and bipole front speakers when I was a 2 channel guy but I realized how incompatible they would be in multichannel. By extension, I also realised the same about their stereo performance, as well.


----------



## BasementBob

Kal Rubinson:


I was just about to post something very similar. Heck, I'll post anyway










For stereo music, thin dipoles placed close to the front wall, or omnipole speakers also close to the wall, sound great. I've heard them. It's not so much that it's relying on the room (well, speakers always do that) but rather that they give the room another opporutunity to create spaciousness by bouncing off the unabsorbed front wall. And the delay is pretty short, so you probably won't notice any degridation if you get the distance from the wall right.


But I once did a test with an omnipole, and the results kinda scared me for home theatre -- even though off axis response with omnipole is pretty even (i.e. almost exactly the same awful curve as the straight out axis).
http://www.bobgolds.com/SpeakerTests/20060810/home.htm 
A monopole speaker response 
An omnipole speaker response


----------



## Kal Rubinson

On the one hand, one can criticise your tests because all these speakers require different boundary relationships to sound right and you tested them even-handedly.


On the other hand, the more they depend on those relations, the more sensitive they are to particular rooms and placement and the more the overall sound is that of the room, rather than the speaker.


----------



## vfrjim

Hmmm, now I am even more confused. I know that I was warned before I purchased my Maggies for Home Theatre use, but the love of thier sound was too good to ignore. When I called Magnepan, they told me that I could reduce the reflective sound(from the rear) using extra acoustic fabric attached to (or under the existing fabric), they told me that using wall treatments behind them is not necessary.


My main problem in my room is a spike @ 500hz and I need to tame that (in addition to some minor bass trapping ) and I have modal ringing that needs to be addressed. My ceiling is acoustic-type ceiling tiles(NRC rating of .75) and carpeted floor (on Drycore) with a 1/2" solid rubber padding(commercial quality). The room is a small room, approx size of 10x15 with 7' ceiling height.


Jim


----------



## Ethan Winer

*Felgar:*


> So then you disagree with many of the conclusions of that Linkwitz lab Room Accoustic site posted a few days back Ethan?


----------



## pepar

Perhaps a "preference" is, as with an opinion, to be more respected (and valid) when it is an educated one. Are dipoles the Pepsi Challenge of speakers? Is the rear radiation - in the right room - the sugar that causes people to prefer dipoles even though they are probably not hearing a faithful reproduction of what the engineer/producer heard? When I was young, I preferred a goosed bass. Not until I became more experienced and educated in sound reproduction did I learn what "flat" was. Until I was enlightened, flat bass sounded anemic. When I finally heard flat bass down to 20Hz, I realized that that was correct. Almost immediately, goosed bass sounded artificial. I overcame my preference for the sugar of a fat bass with education.


I've heard Magnepans a few times and they sounded incredible, but I couldn't say that what I heard was accurate.


----------



## Felgar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> *Felgar:*
> 
> 
> > So then you disagree with many of the conclusions of that Linkwitz lab Room Accoustic site posted a few days back Ethan?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Felgar* /forum/post/0
> 
> 
> the article asserts that the dipole actually has more directly radiated SPL at the listenning position than a monopole in a given room.



It's not clear if those numbers were predicted or actually measured. Small rooms don't really have true reverb, so I'm not sure the same metrics can be applied.


I don't have a lot of personal experience with dipoles, though of course I've heard them. When people used to ask me if they should put absorption on the front wall, I'd always tell them to ask their speaker maker and report back. Finally someone did, and the speaker maker told them that absorption there is good. I don't recall which brand of speaker it was though. Then a few months later I visited a customer with a pair of dipoles, and the speaker maker's rep was there. The rep told me he always recommends front-wall absorption.


If anyone reading this who has dipoles, and is local to me (near Danbury CT), and wants to experiment and run a few tests, send me an email from my company's web site:

www.realtraps.com/contact.htm 


Then we can report the results here.


--Ethan


----------



## Dennis Erskine




> Quote:
> However the article asserts that the dipole actually has more directly radiated SPL



You sure it says SPL not energy? There would be more energy but less audible sound due to phase cancellation...at least in the case of surrounds.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> You sure it says SPL not energy? There would be more energy but less audible sound due to phase cancellation...at least in the case of surrounds.



I haven't gone through the calculation myself, but I believe that the on-axis gain property of a dipole is being used here. A doublet sound source will produce more concentrated on-axis sound pressure at low frequencies*. Same as a dipole surround which is aimed front-rear will produce more pressure along the front-rear axis, rather than the sides. No energy gets lost, of course -- only redirected by a change in directively pattern.


- Terry


* with respect to the source spacing distance


----------



## Felgar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> You sure it says SPL not energy? There would be more energy but less audible sound due to phase cancellation...at least in the case of surrounds.



Well, I interpret "Thus, at 3 m distance from the source, the direct sound would be 20*log(3/0.72) = 12.4 dB below the reverberant sound field for the monopole and only 20*log(3/1.24) = 7.7 dB below it for the dipole." as being SPL, but admittedly it's a little over my head which is the reason I'm asking for more input from the experts here. I believe in this context the speakers in question are the LR mains in a stereo configuration.


----------



## vfrjim




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> It's not clear if those numbers were predicted or actually measured. Small rooms don't really have true reverb, so I'm not sure the same metrics can be applied.
> 
> 
> I don't have a lot of personal experience with dipoles, though of course I've heard them. When people used to ask me if they should put absorption on the front wall, I'd always tell them to ask their speaker maker and report back. Finally someone did, and the speaker maker told them that absorption there is good. I don't recall which brand of speaker it was though. Then a few months later I visited a customer with a pair of dipoles, and the speaker maker's rep was there. The rep told me he always recommends front-wall absorption.
> 
> 
> If anyone reading this who has dipoles, and is local to me (near Danbury CT), and wants to experiment and run a few tests, send me an email from my company's web site:
> 
> www.realtraps.com/contact.htm
> 
> 
> Then we can report the results here.
> 
> 
> --Ethan




I'd be willing, but I am about 100 miles away from you.


----------



## TumaraBaap

Pitting against what the room may contribute to sound appears very fashionable. Taken to the nth degree then, nothing could be better than listening to headphones or having ones he-man rig set up outdoors. It's the sort of specious logic leading some to advocate extensive absorption, in order that the room may not overlay the intended reverb of, say, a subway station or a concert hall.


Granted, a room will usually have an adverse effect on bass tightness, and hence an area where headphones will trump rooms. All other vilification of the room is largely baloney, in my opinion. Of course a well set up room shouldn't be excessively reverberant or have flutter echo issues. For one, distances in such a room are typically so short that it is unlikely reflections will ever overpower reverberation and reflection cues in recorded material. The psycoacoustic Haas or precedent effect with these shorter reflections may actually enhance accurate musical reproduction. If anything, a room with a good balance of reflective/absorptive/ diffusive or scattering surfaces will flatter the output of competent wide dispersion loudspeakers, be they monopole, dipole or omnipole. This is not so because of a taste that has veered to loudspeaker inaccuracy. A mastering engineer's need for clinical evaluation is not the same as that of the end consumer whose goal is simply the most profound enjoyment. The latter also aims for accuracy. However it is accuracy in the context of a wide polar radiation in a well balanced, somewhat lively room, that imparts the most satisfying and enriching reproduction. The mix engineer may have tweaked all the placement cues expediently and efficaciously, but the full musical glory to realize may be for the end consumer with his stellar dipoles in a sensible, "neutral" room. The contribution of a room in such a scenario does not militate against the intentions of the recording and mastering crew.


Indeed, it's interesting to note what sort of loudspeakers earn the highest accolades by the most respectable writers in audio journalism. (please don't refer to stereophile, or I'll prematurely pop an aneurysm)

http://theaudiocritic.com/blog/index...Id=33&blogId=1 


Tumara Baap


----------



## syncophant

Going back to the top of this thread, the following products were listed as good choices for acoustic board:


Owens Corning Select Sound Black Acoustic Board

Owens Corning Fiberglas 703 Series duct insulation.

Johns Manville Insul-Shield

Johns Manville Linacoustic Permacoate rolls.

Certainteed Certpro Acoustaboard Black

Knauf Duct board EI-475

Knauf Duct liner EM


I am hoping someone can suggest where to get one of these products in Canada (Burlington, Ontario area (west end of Toronto)). Failing that, I am willing to drive to Buffalo NY to pick it up. I tried to track down the O/C Black Acoustics board, with no luck.


Thanks.


----------



## LewisCobb




> Quote:
> Originally Posted by *syncophant* /forum/post/0
> 
> 
> Going back to the top of this thread, the following products were listed as good choices for acoustic board:
> 
> 
> Owens Corning Select Sound Black Acoustic Board
> 
> Owens Corning Fiberglas 703 Series duct insulation.
> 
> Johns Manville Insul-Shield
> 
> Johns Manville Linacoustic Permacoate rolls.
> 
> Certainteed Certpro Acoustaboard Black
> 
> Knauf Duct board EI-475
> 
> Knauf Duct liner EM
> 
> 
> I am hoping someone can suggest where to get one of these products in Canada (Burlington, Ontario area (west end of Toronto)). Failing that, I am willing to drive to Buffalo NY to pick it up. I tried to track down the O/C Black Acoustics board, with no luck.
> 
> 
> Thanks.





Do a search for Ottawa Fibre - ofigroup.com I think is the site- they have products similar and I read a thread here a few weeks back from someone in TO area that was using it in his home therater.


Also - you can look on bob golds side for the coefficients that compare all products including the ottawa fiber stuff to see how close or how far off it is from the others.


That's what I'm going with if I ever get around to building my theater and not blasting the money on other toys in the meantime......


Lewis


----------



## Ethan Winer




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> All other vilification of the room is largely baloney, in my opinion. Of course a well set up room shouldn't be excessively reverberant or have flutter echo issues. For one, distances in such a room are typically so short that it is unlikely reflections will ever overpower reverberation and reflection cues in recorded material.



I agree with much of that, but with a few caveats:


Once all of the early reflection points are treated with absorption (or possibly diffusion), other sources of ambience are not particularly damaging. But in the case of dipole speakers, reflections off the front wall are early too. The main problem is not Haas as far as I'm concerned - rather, it's the horribly skewed frequency response from all those separate comb filtering sources.


--Ethan


----------



## TumaraBaap

Of course I'm no expert on this, but I've often wondered why the best dipoles garner the sort of praise they do. What Ethan sees as needless higher frequency SBIR, David Greisinger of Lexicon probably views through the prism of Interaural Cross Correlation and Interaural Time Delay. Maybe the secret to the rich expansive sound of the best dipoles has to do with our binaural hearing mechanism's ability to revel in the chaos of room comb filtering and the brain's skill at extracting sublime beauty out of it. Just a thought.


Tumara Baap


----------



## TumaraBaap

Just thought I'd add no disrespect intended towards any one individual at Stereophile or any other audio medium. I do have a problem with exotic cable sniffing culture. That said I note that the tradition breaking NHT Xd monopole got its due respect in Stereophile. This is a sharp counterpoint to what was meted out to the excellent Paradigm Active 20 a few years ago. Thankfully, there are a few brainy ones who carry their weight around.


----------



## Terry Montlick

Ethan and Tumara,


I see the issue of rear radiation of a dipole speaker as distinct from its directivity. The rear radiation could be absorbed or diffused to eliminate comb filtering, and no change to the front directivity pattern will occur. Of course, it will change the sound to something you may no longer like.










In the sweet spot, which is fairly confined for a dipole, the sound will be minimally affected by the room. In fact, it is less affected by the room at low frequencies than a monopole. A benefit of the "figure eight" dipole directivity pattern is that it has zero side radiation, even at lowest frequencies. If you oriented the dipole so that it is aligned with the front-to-back axis of room, there will be no excitation of the widthwise and heightwise axial room modes. This is true to the extent that the speaker is acting as an ideal dipole. And there are dipole subwoofers, too!


Ethan, to better understand dipole speakers in familiar recording studio terms, think "ribbon microphone" (the kind Johnny Carson used throughout his career). This is just a dipole speaker run in reverse!







In fact, you can make a dipole speaker using a similar ribbon, but it can't move much air so it produces very little bass.


- Terry


----------



## Ethan Winer

Terry,


> Ethan, to better understand dipole speakers in familiar recording studio terms, think "ribbon microphone"


----------



## Ethan Winer




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> Maybe the secret to the rich expansive sound of the best dipoles has to do with our binaural hearing mechanism's ability to revel in the chaos of room comb filtering and the brain's skill at extracting sublime beauty out of it.



As one who agrees with Occam, for now I'll stick with comb filtering as the most plausible explanation.










BTW, comb filtering can be perceived as an improvement in sound quality. If a comb filter null aligns with an "obnoxious" frequency such as the tubby region around 250 Hz or the harsh range around 3 or 4 KHz, the presence of the null might be considered an improvement. Likewise for a comb filter peak that falls on the fullness range around 80 to 120 Hz.


I also mentioned this in the comb filtering video on my company's web site in the context of recording with microphones. Sometimes you'll see recording engineers obsess with tiny changes in microphone placement, especially when recording pianos. I'm convinced this is often a matter of finding peak/null frequencies that complement the instrument more than anything else.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry,
> 
> 
> > Ethan, to better understand dipole speakers in familiar recording studio terms, think "ribbon microphone"


----------



## pepar

Aren't the "teeth" on a comb filter close together and usually thought of as being at higher frequencies (than 250Hz)? Of are you referring to peaks and nulls in the bass region as being part of the comb?


----------



## Tukkis

I don't have 4 solid corners in my room. In a couple I have windows. I won't really need to access these.


Wll bass traps still work well if I have it straddling a room corner and some of it is covering the window?


There are more corners than just vertical room corners. Ceiling to Wall. I want to maximize with the space I have though.


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Aren't the "teeth" on a comb filter close together and usually thought of as being at higher frequencies (than 250Hz)? Of are you referring to peaks and nulls in the bass region as being part of the comb?



The higher frequencies are certainly what I had in mind discussing the inaudibility or even positive effects of room comb filtering.


I suppose the "teeth" can show up elsewhere, like the SBIR distortion in bass when a loudspeaker playing full range without a sub is placed a few feet away from the wall behind.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> As far as I know, figure eight pattern == dipole. I don't think that it is possible to achieve this directivity pattern in any other way.



A regular cone driver not mounted inside a box?


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Aren't the "teeth" on a comb filter close together and usually thought of as being at higher frequencies (than 250Hz)?



Yes, "usually thought of" is the case, but it's not really correct. As TB pointed out, SBIR is also comb filtering. Whatever the cause, comb filtering starts at some low frequency and repeats indefinitely at regular intervals. With acoustic comb filtering caused by reflections, the pattern repeats only at frequencies that are reflected. So for a wall covered with one inch thick 703 the peaks and nulls start low but stop when the 703 kicks in.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> A regular cone driver not mounted inside a box?
> 
> 
> --Ethan



Correct. That's most easily understood as an acoustic doublet == dipole. There is sound radiating from the front and back with opposite phase.


----------



## longfellowfan

Here are my completed Bass Traps and Acoustic Panels. I built 2 2'x2'x2" panels for my early reflection points and 2 2'x4'x4" bass traps for my corners. Also I built 1'x2'x2" panels and placed them behind my Left and Right front speakers, those the panels are not covered with fabric yet. Now the traps and the early reflection panels and consist of owens corning 703 fiberglass framed in pine lumber. The back of the panels are covered in black gardening fabric, which does let air pass but very ugly although it was free from my father. The front of the panel and sides are covered in Guilford of Maine fabric. The difference in audio clarity is dramatic. High freq's are tamer. Bass is tighter. And surround affects are more pinpoint. So here are the photos:
     

Also, you can click my signature for more photos.


----------



## myfipie




> Quote:
> Originally Posted by *longfellowfan* /forum/post/0
> 
> 
> Here are my completed Bass Traps and Acoustic Panels. I built 2 2'x2'x2" panels for my early reflection points and 2 2'x4'x4" bass traps for my corners. Also I built 1'x2'x2" panels and placed them behind my Left and Right front speakers, those the panels are not covered with fabric yet. Now the traps and the early reflection panels and consist of owens corning 703 fiberglass framed in pine lumber. The back of the panels are covered in black gardening fabric, which does let air pass but very ugly although it was free from my father. The front of the panel and sides are covered in Guilford of Maine fabric. The difference in audio clarity is dramatic. High freq's are tamer. Bass is tighter. And surround affects are more pinpoint. So here are the photos:
> 
> 
> Also, you can click my signature for more photos.



It is kind of hard to see and maybe you did, but are you sure you have the thinner panels in the first reflections? Did you use a mirror to find those spots? The one side panel looks kind if high on the wall.




Glenn


----------



## longfellowfan




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> It is kind of hard to see and maybe you did, but are you sure you have the thinner panels in the first reflections? Did you use a mirror to find those spots? The one side panel looks kind if high on the wall.
> 
> 
> 
> 
> Glenn



Yes my fronts are high and I did use the mirror trick before and after placing the panels.


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> It is kind of hard to see and maybe you did, but are you sure you have the thinner panels in the first reflections?



Thinner? I probably missed something along the way here, but isn't thicker better so that first reflection absorption extends as low as possible?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Thinner? I probably missed something along the way here, but isn't thicker better so that first reflection absorption extends as low as possible?



For early lateral reflections which create image shift problems, there is no need to go below 1 kHz. Perceptually, this is a high frequency phenomenon.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> For early lateral reflections which create image shift problems, there is no need to go below 1 kHz. Perceptually, this is a high frequency phenomenon.
> 
> 
> - Terry



Thanks, that makes sense. What about skewing the decay unfavorably toward the upper bass by not using the "opportunity" - no additional HF would be removed - to trap some upper bass?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Thanks, that makes sense. What about skewing the decay unfavorably toward the upper bass by not using the "opportunity" - no additional HF would be removed - to trap some upper bass?



Sure, I never pass up an opportunity to absorb lower frequencies if a room needs it (which a room typically does). Side wall absorbers can do double-duty here. Note that effective treatment of decay times typically requires *many* square feet of absorption, not just the "spot" absorption necessary to handle early reflections.


- Terry


----------



## TumaraBaap




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> For early lateral reflections which create image shift problems, there is no need to go below 1 kHz. Perceptually, this is a high frequency phenomenon.
> 
> 
> - Terry



Surely there's more to it than just an effect on image shift. Also affected (adversely by absorption) is image size. The thickness would also determine the tonality of what's heard (affected adversely by thinner panels). There may also be reason to believe that absorption smothers important spatial cues.


It increasingly seems to me that absorption seems to have a benefit only when listening to mediocre speakers. The Holy Grail of top performance probably lies in attaining perfection in polar response. What's called for is not only a respectable off-axis performance (and a subsequent absence of absorption for this prowess to be realized), but a darn good robust showing in a loudspeaker's extreme off-axis performance. Very few loudspeakers could pull this off well.


A must reading should be the highly regarded Siegfried Linkwitz' ebullient 2007 update of his pet project:
http://www.linkwitzlab.com/orion++.htm 

Also very informative is an older Mix Magazine article summarizing the work of Professor David Moulton at Sausalito Audio Works.
http://www.sawonline.com/wp_mix_article1.shtml 


Tumara Baap


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Thanks, that makes sense. What about skewing the decay unfavorably toward the upper bass by not using the "opportunity" - no additional HF would be removed - to trap some upper bass?



Sure if you can fit them and afford them, then thicker panels are better. But someone should never think that using thicker panels in the early reflections is going to give enough bass control. I always assume people have plenty of bass trapping in the corners.










Glenn


----------



## Terry Montlick




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> Surely there's more to it than just an effect on image shift. Also affected (adversely by absorption) is image size. The thickness would also determine the tonality of what's heard (affected adversely by thinner panels). There may also be reason to believe that absorption smothers important spatial cues.
> 
> 
> It increasingly seems to me that absorption seems to have a benefit only when listening to mediocre speakers. The Holy Grail of top performance probably lies in attaining perfection in polar response. What's called for is not only a respectable off-axis performance (and a subsequent absence of absorption for this prowess to be realized), but a darn good robust showing in a loudspeaker's extreme off-axis performance. Very few loudspeakers could pull this off well.
> 
> 
> A must reading should be the highly regarded Siegfried Linkwitz' ebullient 2007 update of his pet project:
> http://www.linkwitzlab.com/orion++.htm
> 
> Also very informative is an older Mix Magazine article summarizing the work of Professor David Moulton at Sausalito Audio Works.
> http://www.sawonline.com/wp_mix_article1.shtml
> 
> 
> Tumara Baap



This is the Dedicated Theater Design and Construction area, so we should take a cue from that. It is important to remember that any Holy Grail is for a specific ideal listening purpose: 2 channel music, for example. Choose another purpose, and you get a different Grail, and potentially, a completely different engineering solution.


Another must read, and a good example of this, is everything at the ambiophonics site:
http://www.ambiophonics.org 


It comes to a very different conclusion regarding speaker polar response and the use of room treatments. Its rooms are deader than home theaters, and its speakers directional criteria are not the polar response, at least in the normal sense. Compared to other approaches to sound reproduction (high-end two channel music, livish room; high-end movie surround sound, deadish room), it is completely sideways. But its purpose is to create an extremely realistic spacial music experience for a single listener only. And it only needs two channels of source material (old stereo recordings) to do this!


- Terry


----------



## pmeyer

I need advice:


As you can see in this picture, I have three cabinet cavities across the planned screen wall and one on the front of the right wall. The right front corner (where the TV hole is now) is going to be squared off. The cabinets are going away. The screen will be flush with that wall.











Options:


a) remove the cabinets completely and drywall the wall.


b) remove the cabinet fronts and leave them flush to the wall. Fill them with cotton or 703. They'll be covered by GOM or equivalent when I treat my front wall. Essentially free bass traps in non-ideal positions. No implication that they would be the only bass traps (I'm still looking at soffit and corner possibilities).


General plan for now is dead front wall, first reflections left and right, carpet. I'm using CARA to model how much further absorption/diffusion I'll need.


Thoughts?


Paul Meyer

Bee Cave, TX


(see MeyerHT for more pictures and details of my project)


----------



## pepar

I am thoroughly enjoying the discourse between TumaraBaap and Terry Montlick. Having waded through the Toole paper so graciously provided by the former, I know from where he comes.


Absolutely not to take anything away from Dr Toole, but I still need to reconcile his direction - he didn't present it as a conclusion - on absorption with my own senses. And my senses tell me that reducing/eliminating the first (and strongest) reflections will improve imaging. I know that when I added my absorbers (2" OC SelectSound Black) to the first reflection points, I achieved nearfield listening vis-a-vis the LCR speakers at my main seating positions. How can _anything_ be better than nearfield listening? How can letting the room affect what the artist/engineer/producer mixed be better?


----------



## Terry Montlick

pepar,


Again, I think the consequences of side reflections with regard to imaging are dependent upon the specific purpose of the reproduction. Is it for multichannel home theater, for which there are reference theaters which one would like to match? Or is it for conventional stereophonic playback, which has no such reference environments?


Indeed, for the latter, side reflections can be beneficial if done properly, as they can widen the front sound stage (which was Tumara Baap's point). This sense of widening can be accomplished without image shifting or smearing if you play by the correct psychoacoustic rules. This means that the reflections should be below the threshold for such shifting or smearing, but still be audible. Side wall diffusers -- rather than absorbers -- can work very well for this purpose.


- Terry


----------



## Dennis Erskine

...although, Floyd Toole's recent work suggests that the choice of diffusion and absorption (quantity and type) should be dependent upon the quality of the off axis response of the speakers.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> pepar,
> 
> 
> Again, I think the consequences of side reflections with regard to imaging are dependent upon the specific purpose of the reproduction. Is it for multichannel home theater, for which there are reference theaters which one would like to match? Or is it for conventional stereophonic playback, which has no such reference environments?



My multi-channel home theater match a reference theater? Nah, that's not my goal. I think a good home theater goes way beyond any "movie theater." If I'm in the nearfield of "proper" speakers - I'm basically using what a lot of studios use (M&K 150s) - then I'm hearing exactly what the mixdown team did. Am I missing something? How is this not As Good As It Gets?


----------



## TumaraBaap




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I am thoroughly enjoying the discourse between TumaraBaap and Terry Montlick.



Of course, I'm merely a health professional. Terry is an acoustician. I seek concepts and answers from other audio professionals, and largely base my own beliefs on their credibility. I listen to a 7.1 channel system with wide dispersion active loudspeakers myself but otherwise have very limited exposure to the best systems. Frankly, I doubt I'll have the time to fully peruse through extensive links as the one provided by Terry (gracias by the way...will check it out). I don't always have an answer for the ever inquisitive Honcho of this thread either ;-) So take what I have to say with a grain of salt.


However, my thoughts on this: If a Theater/Music enthusiast wants to choose seven wide dispersion loudspeakers such as the NHT Xd over the ample competition, design a room with broadband absorption on the center portion of the backwall and ceiling, go with extensive bass trapping, and otherwise eschew the thin panel absorption elsewhere that seems to be the acoustic norm, it would indeed be a stride taken with the grail in mind. I concede that with multi channel systems, one can get away with directional loudspeakers or poor loudspeakers plus lots of early reflection absorption. The more the channels, the more the leeway with that approach. But that doesn't amount to respective stereo and muli-channel speaker/room systems being at an absolute tangent in their quest for perfection. In that vein proprietary 10 channel surround formats such as by Audyssey try to make up for the dearth of reflection cues in a 5.1 or 7.1 channel formats, especially the front soundstage. Linkwitz' system, already enriched with sonic energy from the front soundstage thanks to its inherent dipole design with excellent polar radiation raises the bar with four wide dispersion omnipoles utilizing a surround format similar to Chesky's six speaker setup. Granted the role of reflections in a multi channel system are far from established. But there seems nothing incompatible with an *accurate* wide dispersion loudspeaker system/lively room combo and multi channel formats either. The NHT Xd owner just might as well be making a precocious move to reference systems of the future based on such central ideas...

Tumara Baap


----------



## Dennis Erskine




> Quote:
> Am I missing something? How is this not As Good As It Gets?



Yup. Room size.


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> Of course, I'm merely a health professional. Terry is an acoustician. I seek concepts and answers from other audio professionals, and largely base my own beliefs on their credibility. I listen to a 7.1 channel system with wide dispersion active loudspeakers myself but otherwise have very limited exposure to the best systems. Frankly, I doubt I'll have the time to fully peruse through extensive links as the one provided by Terry (gracias by the way...will check it out). I don't always have an answer for the ever inquisitive Honcho of this thread either ;-) So take what I have to say with a grain of salt.
> 
> 
> However, my thoughts on this: If a Theater/Music enthusiast wants to choose seven wide dispersion loudspeakers such as the NHT Xd over the ample competition, design a room with broadband absorption on the center portion of the backwall and ceiling, go with extensive bass trapping, and otherwise eschew the thin panel absorption elsewhere that seems to be the acoustic norm, it would indeed be a stride taken with the grail in mind. I concede that with multi channel systems, one can get away with directional loudspeakers or poor loudspeakers plus lots of early reflection absorption. The more the channels, the more the leeway with that approach. But that doesn't amount to respective stereo and muli-channel speaker/room systems being at an absolute tangent in their quest for perfection. In that vein proprietary 10 channel surround formats such as by Audyssey try to make up for the dearth of reflection cues in a 5.1 or 7.1 channel formats, especially the front soundstage. Linkwitz' system, already enriched with sonic energy from the front soundstage thanks to its inherent dipole design with excellent polar radiation raises the bar with four wide dispersion omnipoles utilizing a surround format similar to Chesky's six speaker setup. Granted the role of reflections in a multi channel system are far from established. But there seems nothing incompatible with an *accurate* wide dispersion loudspeaker system/lively room combo and multi channel formats either. The NHT Xd owner just might as well be making a precocious move to reference systems of the future based on such central ideas...
> 
> Tumara Baap



Wow, you've obviously given this a lot of thought, so who besides you would be best suited to execute it? I'll gladly provide you with server storage space for the blog of your new project!


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Yup. Room size.



In the nearfield (of a room with smooth bass response), there is no spoon, er . . room.


----------



## Dennis Erskine

But, if you're in the nearfield to the extent the room effects are not audible, then you don't really care about the room, reverberent field, surround channels, etc. Equally to the point, the more in the nearfield you are, the more critical that you have exactly the same speakers as the engineer used during the mix...the closer to the speaker the greater the impact of speaker differences on the mix and what you hear.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> But, if you're in the nearfield to the extent the room effects are not audible, then you don't really care about the room, reverberent field, surround channels, etc.



That's exactly my point. It's in fourth place in having one-to-one control of our eardrums, just behind in-ear monitors, and high quality on- and around-ear headphones. You are there.



> Quote:
> Equally to the point, the more in the nearfield you are, the more critical that you have exactly the same speakers as the engineer used during the mix...the closer to the speaker the greater the impact of speaker differences on the mix and what you hear.


_Exactly_ the same speakers or very good and very close? I would think it more comes down to the skills of the artist, producer and engineer in creating a believable environment (in their mix). If it's a hackneyed mix, it will be (painfully) obvious to the listener.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> If I'm in the nearfield of "proper" speakers - I'm basically using what a lot of studios use (M&K 150s) - then I'm hearing exactly what the mixdown team did.



Not necessarily. You'd have to put your ears literally next to the loudspeakers to be close enough to overcome the room effects. Now _that_ would be nearfield!










--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Not necessarily. You'd have to put your ears literally next to the loudspeakers to be close enough to overcome the room effects. Now _that_ would be nearfield!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Or we could just wait for the HeaDMI interface.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Or we could just wait for the HeaDMI interface.



Only if you have your head retrofitted to be compatible with HeadDCP!


----------



## Tukkis

Why not just wear headphones. Then you would never have to worry about room acoustics and bass traps. I wonder what the first reflection points between headphones and ears would be?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Tukkis* /forum/post/0
> 
> 
> Why not just wear headphones. Then you would never have to worry about room acoustics and bass traps. I wonder what the first reflection points between headphones and ears would be?



Cute. My personal issue with headphones is that they simply cannot recreate the soundstage on stereo or mch recordings unless they are binaural recordings or subjected to lots of reprocessing.


----------



## pepar




> Quote:
> Originally Posted by *Tukkis* /forum/post/0
> 
> 
> Why not just wear headphones. Then you would never have to worry about room acoustics and bass traps. I wonder what the first reflection points between headphones and ears would be?



Ethan: Are you following this? There could be a whole new untapped market for wee lit'l traps and diffusors. And you'll need wee wee WEE lit'l microphone capsules for testing.


"My mommy said not to put traps in my ears . . . "


----------



## Terry Montlick

A major problem with headphone imaging is that center channel sound often appears to be coming from your brainstem.










- Terry


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> A major problem with headphone imaging is that center channel sound often appears to be coming from your brainstem.
> 
> 
> 
> 
> 
> 
> 
> - Terry



Some people listen only with their brainstems.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> Some people listen only with their brainstems.



In the end, it all goes through the brainstem.


I had hoped to stop with this silliness, but . .


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Ethan: Are you following this? There could be a whole new untapped market for wee lit'l traps and diffusors. And you'll need wee wee WEE lit'l microphone capsules for testing.
> 
> 
> "My mommy said not to put traps in my ears . . . "



We sell them!!!! It is called the GIK Cuetip. Just mount them in all corners of the headphones.










Glenn


----------



## S2G-Unit

My screen wall if covered in rigid fiberglass. MY false wall is only 2 feet deep.


All the fiberglass is currently spaced out about 1.5", with 2" fiberglass. I'm very limited in space back there. So could I double up on fiberglass in some places back there (where the speakers aren't). So half would 2" spaced 1.5". The other half would be 4" spaced 1.5".



Or does it all have to be the same thickness.


----------



## BasementBob

S2G-Unit:

The difference in absorption between {4" spaced 1.5} vs {2" spaced 1.5} is relatively minor. Pretty much no change at all above 250hz.

The 4" will do more absorption in frequencies lower than that, but not a lot more, and not a lot lower.

The significant change would be from about 50hz to 200hz. With 50hz moving from about 0.02 to 0.10, and 100hz moving from about 0.20 to 0.40, and 200hz moving from about 0.40 to 0.70. (source: ChrisW's spreadsheet, 0 degree incidence not diffuse)


----------



## S2G-Unit

OK perfect,


So would it be ok to have some 2 thick and some 4 thick all behind the screen? Do they all have to be the same thickness?


Last thing for Bob, Terry or Ethan and Bpape.

I used to have a bookshelf in the room along the wall. I did not dry wall over the space it fit in. I did not want the long walls would to be perfectly parallel (would have more echo I think). The size is approx 24"W x 13"Dx 7'H.


I'm guessing I could make 2 small floor to ceiling superchunks in the right?

But it would not be symmetrical to the other side of the room.


----------



## Emanuele

Some times ago (back to 2005) Easley posted a *First Point of Reflection Calculator*.


Somebody can send me a copy ?


I've used the mirror method to calculate first point of reflections, but a tool can be useful to confirm my findings.


bye

Emanuele


----------



## Ethan Winer




> Quote:
> Originally Posted by *Emanuele* /forum/post/0
> 
> 
> I've used the mirror method to calculate first point of reflections, but a tool can be useful to confirm my findings.



This article on my company's site explains how to calculate the reflection points without needing a mirror:

http://www.realtraps.com/art_room-setup.htm 


--Ethan


----------



## Emanuele




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> This article on my company's site explains how to calculate the reflection points without needing a mirror:
> 
> http://www.realtraps.com/art_room-setup.htm
> 
> 
> --Ethan



thanks Ethan, I'll read it.


bye

Emanuele


----------



## Emanuele




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> This article on my company's site explains how to calculate the reflection points without needing a mirror:
> 
> http://www.realtraps.com/art_room-setup.htm
> 
> 
> --Ethan




Ethan,

may I use the same formula you suggest for wall reflection, also for calculating the first reflection on ceiling ?

Because I have my central channel lower than my ear, so just going at half the way between my ear and that channel doesn't work.


Another question: my sofa is really close (10 cm) to rear wall.

May I use just absorber here or you think it's better diffusion ?

Or may I mix it, using absorber just rear my head and diffusion upper ?


thanks

Emanuele


----------



## Ethan Winer




> Quote:
> Originally Posted by *Emanuele* /forum/post/0
> 
> 
> may I use the same formula you suggest for wall reflection, also for calculating the first reflection on ceiling ?



Sure.


> my sofa is really close (10 cm) to rear wall. May I use just absorber here or you think it's better diffusion ?


----------



## bpape

If you have some room behind the couch down low, you'll find that some good thick absorbtion there will also help considerably.


Bryan


----------



## Winkelmann

Has anyone here used RPG Flutter Free for a rear wall?


----------



## DMF

I'd like some thoughts on an optimum treatment, please. Particularly what absorption spectrum to shoot for.


The room is about 22'x13'x8', not counting the AV alcove in the front wall. (It used to be a fireplace.) Standard drywall construction, floor on joist. Viewing position is about room center, and the rear is broken up by another alcove and hallway openings to each side. Most of the floor is covered by area rugs. Subs are close to the midpoints of the side walls. There is 100 sq ft of acoustic panels (2" 6.0 pcf JM Whispertone with a 2" air gap) on the front sidewalls, from before the first reflection points past and surrounding the side speakers.


The ex-fireplace alcove at the front is flanked by windows. To hide the equipment when not watching, and cover the windows when watching, I have installed two sliding panels, each 7'6" x 3'4" (48 sq ft). The panels are wood-frame, open front and back, and will be covered by fabric. They are built to accept 4" of something. The question is what?


Before I put in the side panels there was a definite slap echo. That's largely gone and the room is not hideously live, but the live front wall (windows and glass TV screen) doesn't help. So I need some mid-high absorption up there. The primary need is for bass absorption. The floor tends to ring at around 40 Hz. There are acoustic decouplers under the subs, but response is still uneven.


Bob Golds tables for 4" OC700 show these numbers
Code:


Code:


Product         thickness       mounting        density         125hz   250hz   500hz   1KHz    2KHz    4KHz 

701, plain      4" (102mm)      on wall         1.5 pcf         0.73    1.29    1.22    1.06    1.00    0.97  
701, plain      4" (102mm)      16" air         1.5 pcf         0.87    1.14    1.24    1.17    1.18    1.28 
703, plain      4" (102mm)      on wall         3.0 pcf         0.84    1.24    1.24    1.08    1.00    0.97    
703, plain      4" (102mm)      16" air         3.0 pcf         0.65    1.01    1.20    1.14    1.10    1.16 
705, plain      4" (102mm)      on wall         6.0 pcf         0.75    1.19    1.17    1.05    0.97    0.98    
705, plain      4" (102mm)      16" air         6.0 pcf         0.59    0.91    1.15    1.11    1.11    1.19 
703, FRK        4" (102mm)      on wall         3.0 pcf         0.88    0.90    0.84    0.71    0.49    0.23    
705, FRK        4" (102mm)      on wall         6.0 pcf         0.65    0.52    0.42    0.36    0.49    0.31    
1240            4" (102mm)      A               4.0 pcf         0.88    1.14    1.17    1.08    1.06    1.10 
1260            4" (102mm)      A               6.0 pcf         0.99    1.01    1.10    1.03    1.03    1.05 
1280            4" (102mm)      A               8.0 pcf         1.11    0.91    1.07    1.03    1.06    1.07

"Differences in coefficients of less than 0.15 are not significant."


1) Does it make sense to use FRK (faced) to keep from eating too much of the mid/highs? Or is there enough coverage to matter?


2) Ethan Winer reports that increasing density increases bass absorption (up to a point). Yet, at least with the 700 series, the data appears to illustrate the opposite trend. Might he have been working at lower frequencies?


3) Like the density correlation, the air gap seems to have a contrary influence. (Gap behind mine will be 2-4".)


4) Can we extrapolate these numbers below 125Hz with any confidence?


Anything other significant factors, like cost and availability? (OC705 seems hard to come by, for instance.)


----------



## BasementBob

DMF



> Quote:
> Bob is adamant elsewhere that increasing density increases bass absorption



Really?

I guess that's true in the fairly thin (0.5" to 2"-ish).

What increases bass absorption is deeper/thicker material. Anything over a foot deep, consider much less dense.


BTW, Eric Desart did a really nice graph with comments based on the data on my page and others.



> Quote:
> 1) Does it make sense to use FRK (faced) to keep from eating too much of the mid/highs? Or is there enough coverage to matter?



Depends on what else is in the room, and where you're placing these. For example, FRK covered are probably not appropriate at the first reflection points.


----------



## DMF

Oops. It was Ethan Winer's site. "My own tests in a certified acoustics lab confirm this, showing denser types of rigid fiberglass absorb as much as 40 percent more than less dense types at 125 Hz and below." here 


When my panels are open they butt into the corner, adjacent to the 2" panels.


----------



## bpape

IMO, since it's on the front wall, FRK/FSK is not recommended. We want the front wall dead in the mids and highs.


Bryan


----------



## DMF

Bryan, how does 4" mineral wool compare acoustically to 705? How is it to handle?


----------



## bpape

Mineral wool is more 'crumbly' than 705. It's OK to handle but a bit itchy and very dusty.


To me, for the front wall application, I'd stay with 703.


Bryan


----------



## Ethan Winer




> Quote:
> Originally Posted by *DMF* /forum/post/0
> 
> 
> Oops. It was Ethan Winer's site. "My own tests in a certified acoustics lab confirm this, showing denser types of rigid fiberglass absorb as much as 40 percent more than less dense types at 125 Hz and below." here



Also see my Density Report:

www.ethanwiner.com/density/density.html 


--Ethan


----------



## TumaraBaap




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Mineral wool is more 'crumbly' than 705. It's OK to handle but a bit itchy and very dusty.
> 
> 
> To me, for the front wall application, I'd stay with 703.
> 
> 
> Bryan



From what I understand, OC 703 and 705 tend to hold their shape better than mineral wool. This would make 703 or 705 better for panels. But what about superchunk style traps? These devices are easy to build, easy to place, easy to stack up and are very effective absorbers. The downside is that the mass closest to a wall has little air particle velocity and contributes little to absorption. Cost then becomes a consideration with 703 or 705 as the raw material. But wastage isn't a big issue if using the far less expensive and easily procured mineral wool boards. Since the device is a solid mass block, rigidity of the starting panels shouldn't be an issue either.

This is how I am planning to do my corner traps. I'll dress up the mineral wool superchunks with weed fabric, and incorporate them behind the layers of stage velour at the proscenium. They'll be out of sight and provide superb broadband absorption.

Tumara Baap


----------



## pepar




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/0
> 
> 
> . . . what about superchunk style traps? These devices are easy to build, easy to place, easy to stack up and are very effective absorbers. The downside is that the mass closest to a wall has little air particle velocity and contributes little to absorption. Cost then becomes a consideration with 703 or 705 as the raw material. But wastage isn't a big issue if using the far less expensive and easily procured mineral wool boards. Since the device is a solid mass block, rigidity of the starting panels shouldn't be an issue either.
> 
> This is how I am planning to do my corner traps. I'll dress up the mineral wool superchunks with weed fabric, and incorporate them behind the layers of stage velour at the proscenium. They'll be out of sight and provide superb broadband absorption.



The Studiotips SuperChunks seems to me to be the easiest and most economical way to DIY yourself into some seriously effective bass traps. Not everyone's theater can accommodate the 34" cut, but even the 24" cut seems quite effective.


OC 703/705 can be difficult to find at a price reasonable enough to meet the "most economical way to DIY" criteria I mentioned above; many acoustical treatment companies and individuals sell it, but one needs to get to the "source" for the best pricing. The original, and still by far the largest, use of this material is HVAC insulation. Sooo, the source is a distributor of HVAC materials. I am fortunate enough to live a mere 30 mins from the corporate headquarters of just such a company, Specialty Products & Insulation , but they have locations all over the U.S. I know from reading here and on other forums, this company is well known among home theater enthusiasts.


----------



## bpape

As you get thicker, density has less of an effect. Doing a solid chunk style absorber is thick enough that 703 is plenty dense and easy to work with - not to mention being half the price of 705.


Bryan


----------



## HT-Naimee

Hi all!


I have a lot of problems with echos and reverberations. Even during normal conversations I can hear my voice get distorted. Not to mention clapping my hands or snapping my fingers.


Now I am new to room acoustics and unfortunately there is no professional within a 100miles of where I live in Germany.


So could you guys give me some tips as to where to start and what to do?


I can post some pictures if that helps. It's currently a living room/music/HT room as I do not own a house yet. I looked into buying absorbers but they are so expensive I do not want to just spend 1k on absorbers and end up with the same poor sound I left off with.


----------



## S2G-Unit

Ok guys,

I have bass traps in all 4 corners of my HT room. I also have a small indentation in the room, where a bookshelf was (13"Dx28"W). I have already put 2 superchunks in that space. Should I instead just fill the caivity completly instead of having 2 superchunks there? More mass?


I've got tons of Fiberglass left.


----------



## pepar




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> Hi all!
> 
> 
> I have a lot of problems with echos and reverberations. Even during normal conversations I can hear my voice get distorted. Not to mention clapping my hands or snapping my fingers.
> 
> 
> Now I am new to room acoustics and unfortunately there is no professional within a 100miles of where I live in Germany.
> 
> 
> So could you guys give me some tips as to where to start and what to do?
> 
> 
> I can post some pictures if that helps. It's currently a living room/music/HT room as I do not own a house yet. I looked into buying absorbers but they are so expensive I do not want to just spend 1k on absorbers and end up with the same poor sound I left off with.



Absorption can be overdone. It's common to treat only the first reflection points - all of them - and see what that does. I can't imagine that NOT making a HUGE improvement. Front wall and back wall are first reflection points along with ceiling, floor and left/right front sidewalls. A nice thick rug can be used on the floor.


----------



## BasementBob

HT-Naimee:


Flutter echo (that twang you hear when you snap your fingers) is the easiest of acoustic problems to get rid of.


The easiest way is to let a woman loose in the room. By the time they're done decorating usually flutter echo is gone.



The next thing to work on is knowing that flutter echo is caused by sound bouncing back and forth between large parallel surfaces. In this case 'large' can be as small as 4'x4'. These surfaces are usually wall-wall, or floor-ceiling.


The next thing to know about flutter echo is that the annoying sound you are hearing isnot actually the sound that's going past. What you're hearing is the interaction of two higher frequency waves, causing a 'beat' like lower frequency to be heard. This is really great because it's easier to absorb higher frequencies than lower ones.


All you need to do is to stop flutter is to put something that will either:

a) reflect the sound away from the other parallel surface (e.g. a diffuser, an unevenly shapped armoir, a book case, etc)

b) absorb the high frequency sound


For (b) you can use anything soft. Even thin drapes. Or a lot of big plants.


As an experiement, hang a couple of comforters/duvets or sleeping bags on a wall (wall-wall flutter). If you have friends handy, they can hold it in place. If not you can temporarily hold it in place with anything from broom handles, to a horizontal piece of wood attached to the wall.

Cover the floor in carpet/rug(s) (floor-ceiling flutter).


If the problem is floor-ceiling or front-wall-back-wall, then treating one surface is fine.

For left-wall-right-wall, you probably want to maintain symmetry, so treat both surfaces equally.



Using 1" of rigid fiberglass (eg Linacoustic) is better than a comforter, particularly at the first reflection points, because rigid fiberglass's absorption is more even above 1000hz. Ignoring imaging, optimally you want reflections to have the same tonality as the speaker -- and if you can't get that then you want the reflections absorbed/diffused into insignificance.

DIY 2'x4'x2" absorbers are easy to make. I've done woodworking since I was quite young, so that's how I did it. But you can also buy bags to cover rigid fiberglass, which isn't any harder than putting on a shirt.


----------



## BasementBob

S2G-Unit:

Post a scale floor plan.


----------



## Ethan Winer




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> I have a lot of problems with echos and reverberations. Even during normal conversations I can hear my voice get distorted ... So could you guys give me some tips as to where to start and what to do?



Start here:

http://www.ethanwiner.com/acoustics.html 


Understand that obvious echoes are only half the story. Just as important is getting the bass range correct. But you may not notice the bass problems until after you tame the mids and highs.



> Quote:
> I do not want to just spend 1k on absorbers and end up with the same poor sound I left off with.



If you get _good_ acoustic treatment you will greatly improve the sound at all frequencies.


--Ethan


----------



## HT-Naimee

Thank you both for your interest and help. First thing tomorrow morning (it's 10:30pm now) I will take some pictures and post them.


I will try to read up everything I can by then. I hope you two will be able to help me with this.


By the way, if it is ceiling to floor (laminate floor and bare white ceiling), will it suffice to "treat" the floor or is it necessary to treat the ceiling?


I hope the pictures will be able to help analyze my room.


Room is 3.4m x 5.6m . I am firing across the room and sitting against the rear room. Not ideal acoustically, but for some reason it still sounds best (and is the best and currently only way to position the system).


Looking forward to your views and thanks again!


Alex


----------



## DMF




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> By the way, if it is ceiling to floor (laminate floor and bare white ceiling), will it suffice to "treat" the floor or is it necessary to treat the ceiling?



Doing the floor, two side walls, and maybe one other wall (might be pointless with your configuration) is usually quite enough.


Also, beware reflective surfaces between you and the speakers. No glass coffee tables.


----------



## BasementBob




> Quote:
> By the way, if it is ceiling to floor (laminate floor and bare white ceiling), will it suffice to "treat" the floor or is it necessary to treat the ceiling?



From a flutter perspective, it is not nessessary to treat the ceiling if the floor is carpeted. "If the problem is floor-ceiling or front-wall-back-wall, then treating one surface is fine."



> Quote:
> Also, beware reflective surfaces between you and the speakers. No glass coffee tables.



This is a different effect -- comb filtering. For it to be flutter you'd have to be leaning over the table (without a pillow).

Although comb filtering is easy to detect with real time analyzer equipment, most people do not hear it.


----------



## HT-Naimee

I do not know what effect precisely I have, nor whether I only have one sole effect causing the sonical problems.


Unfortunatly I had to go to university early this morning and was unable to take any pictures.


My room is more or less bare, though. No curtains (I don't like them), one big carpet on the laminate floor (between me and the speakers) which is about 1-2cm thick, but quite "rigid". The walls are more or less empty with only a few picture frames but nothing really diffusing.

I hope to be able to take some pictures when I get home tonight.


----------



## HT-Naimee

I do not know what effect precisely I have, nor whether I only have one sole effect causing the sonical problems.


Unfortunatly I had to go to university early this morning and was unable to take any pictures.


My room is more or less bare, though. No curtains (I don't like them), one big carpet on the laminate floor (between me and the speakers) which is about 1-2cm thick, but quite "rigid". The walls are more or less empty with only a few picture frames but nothing really diffusing.

I hope to be able to take some pictures when I get home tonight.


----------



## CriticalListener




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> I have a lot of problems with echos and reverberations. Even during normal conversations I can hear my voice get distorted. Not to mention clapping my hands or snapping my fingers.



Let me first say I agree with the advice already given from Ethan and the others, but I'll try to make this less technical. Based on your quote above, I would not bother with reflection points - yet. What you need to do is fill your room with stuff (preferably soft stuff). Get a couch or loveseat, hang things on the walls. I know you said you don't like drapes, but get something - acoustical panels would be wonderful.


Sound needs to be absorbed or it will keep bouncing around until it loses all its energy - soft things tend to absorb sound. After you fill the room, then you should begin thinking about bass treatment, frequency response measurements and the rest. Take it slow and you'll notice a great improvement - then immerse yourself in this thread, Ethan's site and other online material. Don't try to do it all at once.


Good luck!


----------



## vipercompany

is it necessary to go from the floor to ear level on the side walls? Also any acoustic experts, please check out my thread in this forum, I need help putting up my panels. Thanks!


----------



## bjolish

Please note that I posted this message outside the thread a few days ago, but didn't receive a response. Maybe this is the better place for help.


Thanks


--------------------------------------------------------------------------------


Dear home theater gurus,


I'm in the process of planning a new house and, of course, home theater. I've spent many hours on the forum, and now have a vague sense of my options. I'm hoping some of you can take a few minutes to help me firm things up re acoustical treatments. (I've posted a separate question re noise isolation.)


The room layout is in the image below. The is about 18' long, from the screen wall to the rear wall. The room will be about 13.5' wide. The ceiling will be 8' high. I'll have one or two rows of sofas or large home theater chairs, no closer that 2' to the back wall.











Please also note that the screen wall will have an opening to the closet, so that I can access the DVD player, receiver, etc. The opening will be below the screen, about 12 high and about 8' long (and would be closed with glass doors). (I've planned the closet equipment shelf opening so as to avoid IR repeaters, see the cable box channel display, easily load DVD's, etc.) The closet will have a vent to an exterior room. There are also a door and window in the rear wall.


The projector will be mounted on a rear wall shelf. The speakers will all be wall- mounted KEF KHT6000s (6.2 configuration). I'm not sure where the sub should sit.


Here's my acoustical treatment strategy:


Font wall: I know the general rule is to treat the front wall with lots of absorptive material, but I'm wondering if this would be a mistake given that the KEF 6000s are specifically designed to be wall-mountedi.e., their design probably already compensates for rear-wall reflections.


Rear wall: Curtains backed with thick blackout shades along entire wall, for diffusion and light control. I know having the rear seats so close to the rear wall is not ideal, but I want to maximize seating. Should I add more diffusion behind the curtains (e.g. with some foam products from partsexpress.com)?


Side walls: 1 OC 703 velcroed to the walls to 48 from floor (i.e., to ear level). Note, however, that the LEF 6000s will be wall mounted. Does that mean I should adjust the OC 703 on the walls? If so, how?


The whole wall would then be covered by a light curtain (i.e., like at a modern movie theater). Hopefully I can use something inexpensive and pre-made (i.e., not GOM)--maybe a thin velvet. I don't want to make the room too dead, but I don't see how the thin curtain material would be any more absorptive than the cotton batting lots of people are using on the walls.


Ceiling: No treatment.


Floor: Wood subfloor (over concrete slab) with pad and carpet.


Rear corners: Bass traps, consisting of 2 layers of OC 703 at 45 degree angle to wall. They would start about 4' up, and extend to the ceiling. I don't think I can fit 2' wide panels, but I assume any width is better than nothing. Should I stuff the traps with something to add mass?


2 final miscellaneous questions:

Projector shelf: I'm planning on a Panasonic PT-AX100U, which is supposed to be pretty quite. Nonetheless, would it do any good fine to line the inside bottom of the shelf with OC 703? I don't think I need to bother with an entire hush box.


Subwoofer: I'd like to keep the subwoofer (or maybe 2 subwoofers) away from the front wall, so that the kids can use the area. I know I'm supposed to do the subwoofer seating position test for optimal placement, but at this point can anyone opine on whether it may be OK to place the sub(s) along the rear walls, about 4' from the corner?


Thanks to all who take the time to help. I'm eager to for your feedback.


----------



## HT-Naimee

OK, sorry for the delay but now I hopefully have the info needed to judge my room.


Here is the layout. As you can see I am using half of the room for my music. I tried using the lenght of the room but that was not satisfactory at all. I quite like it the way it is now....except for the reverberations/echoes









 


First of the front speakers. Please ignore that tiny old TV but mine died on me and I am currently looking for a 50"-60" flatscreen. So, ignore that part
















 



In the left part of the picture you can see a big cupboard. Wooden, more or less even surface.


Next the far corner. On the layout picture this would be left and you can see the cupboard on the right.

 


Moving further (counter-clockwise)

 


And arriving at the listening position or rather the wall opposite te fronts. You can see the rear left speaker at the bottom.

 


And further (you can just see the top of my rack with my DVDP in the bottom left corner.


----------



## bpape

1. Get the sub out of the corner.

2. Move the front speakers out away from the front wall a bit

3. Get the listening position away from being right up against the wall.


Those are all the 'free' things you can do to improve the sound.


Bryan


----------



## HT-Naimee




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> 1. Get the sub out of the corner.



Two subs actually. But they are not being used for stereo and the bass is fine.



> Quote:
> 2. Move the front speakers out away from the front wall a bit



These speakers (Naim Audio Allae) are made to be up against walls and you can adjust the amount of bass they do by moving them closer or away. I like the amount of bass they give that close and the reverberations do not change when moved away (tried it







).



> Quote:
> 3. Get the listening position away from being right up against the wall.



Well, I tried moving away about 30-50cm but it didn't change the problem. It only looks bad and feels weird sitting in the room like that. Unfortunately not a cure for my problems.



> Quote:
> Those are all the 'free' things you can do to improve the sound.
> 
> 
> Bryan



Unfortunately I think those will be the tweaks once the vital room acoustics have been dealt with


----------



## BasementBob

HT-Naimee:


What happens if you rotate your viewing 90 degress

by putting the TV under the shelf instead of under the photos.

That'll give you more symmetry, and air behind your head.


Two subs in the new front corners may be fine. (Floyd Toole sub paper)


----------



## HT-Naimee

I tried turning 90° (I think I mentioned it before), but unfortunatly it actually made the sound worse. The reverberations remained more or less the same (impossible to say without measuring). But the music lost its life and everthing sounded dull to me.


On top of the poor sound, it also looked pretty awefull










I guess I would really be interested in all of your views on where to install treatments and how much I would need to kill off all reverberations.


----------



## Ethan Winer




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> I would really be interested in all of your views on where to install treatments and how much I would need to kill off all reverberations.



It's all explained in my Acoustics FAQ:

http://www.ethanwiner.com/acoustics.html 


--Ethan


----------



## CriticalListener

I know this sounds over simplified, but after looking at your pictures you have nothing on your walls. You need soft stuff to absorb the sound. I'd definitely go to www.realtraps.com and get at least two MicroTraps (2' by 4'). It's not enough to make your room perfect, but you will be amazed at how an under $300 investment can impact on your sound quality.


I can honestly say that the


----------



## eugovector

Or take that same $300 and build 12 of your own panels.



> Quote:
> Originally Posted by *CriticalListener* /forum/post/0
> 
> 
> I know this sounds over simplified, but after looking at your pictures you have nothing on your walls. You need soft stuff to absorb the sound. I'd definitely go to www.realtraps.com and get at least two MicroTraps (2' by 4'). It's not enough to make your room perfect, but you will be amazed at how an under $300 investment can impact on your sound quality.
> 
> 
> I can honestly say that the


----------



## HT-Naimee

OK. So the two walls I could work with are the one behind the listening position and the wall to my left, where the two brwon picture frames are.


Now my question would be, how much do I need and what sizes? Would I really need to cover the entire far wall and all of the wall behind me or will I just need three or four absorbers overall with each the size of those picture frames?


----------



## Terry Montlick




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> OK. So the two walls I could work with are the one behind the listening position and the wall to my left, where the two brwon picture frames are.
> 
> 
> Now my question would be, how much do I need and what sizes? Would I really need to cover the entire far wall and all of the wall behind me or will I just need three or four absorbers overall with each the size of those picture frames?



It depends on the quality/accuracy you want to achieve. But covering 25% of the wall area with wideband absorption is not at all unreasonable. Front wall and side walls toward the front of the room are prime areas. Every room is different, but 2" thick mineral wool or other dense porous absorber should make a *dramatic* difference.


Regards,

Terry


----------



## DMF




> Quote:
> Originally Posted by *bjolish* /forum/post/0
> 
> 
> Font wall: I know the general rule is to treat the front wall with lots of absorptive material, but I'm wondering if this would be a mistake given that the KEF 6000s are specifically designed to be wall-mountedi.e., their design probably already compensates for rear-wall reflections.



If speakers could compensate for room acoustics, we wouldn't need sound treatments. Disabuse yourself of this notion. The only time you'd worry about nearby wall treatments is if the speaker configuration is that of a dipole. Rear (high frequency) radiators rely on reflections.



> Quote:
> The whole wall would then be covered by a light curtain (i.e., like at a modern movie theater). Hopefully I can use something inexpensive and pre-made (i.e., not GOM)--maybe a thin velvet. I don't want to make the room too dead, but I don't see how the thin curtain material would be any more absorptive than the cotton batting lots of people are using on the walls.



First off, the material needs to be fire resistant/flame retardant. It isn't the acoustic properties that make (e.g.) GOM expensive, it's the fire rating. You don't have to use it, but use something equally safe.


Second, the cloth covering is not intended to absorb anything. Quite the opposite - it's intended not to absorb anything. Likewise it's intended not to _reflect_ anything either. The absorptive material underneath will be pointless if energy is reflected by the covering fabric before it ever gets there.


----------



## HT-Naimee

OK, now, if I were to make my own of mineral wool, glas-wool, say 2" thick, would I be allowed to squeeze it or would it need to remain as loosly as possible?


And is it important at which height I hang the absorbers? e.g. how about one lonish one (2m x 0.50m) over the wooden door, one on the door itself and then one big one behind my listening position?


----------



## eugovector

You won't be able to squeeze it, it's already compressed and set in a resin. My frames were a little too small for your standard 2x4 slab, and I literally had to break down the ends to get it to fit (though it's in there good now).


If you're thinking of using the fluffy stuff, you're thinking of the wrong material.


Please read Ethan's FAQ on placement. Yes, height is crucial.



> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> OK, now, if I were to make my own of mineral wool, glas-wool, say 2" thick, would I be allowed to squeeze it or would it need to remain as loosly as possible?
> 
> 
> And is it important at which height I hang the absorbers? e.g. how about one lonish one (2m x 0.50m) over the wooden door, one on the door itself and then one big one behind my listening position?


----------



## HT-Naimee

OK, I will have to go to our shops again and look around. Most stuff was the fluffy kind rather than rigid. Maybe I overlooked it.


Did I miss the part in Ethan's text where to place the absorbers? By the way, Ethan, very nice work! Now I just need to find the German fibreglass stuff that corresponds to 703 and need to know where to hang the absorbers.


----------



## CriticalListener




> Quote:
> Originally Posted by *HT-Naimee* /forum/post/0
> 
> 
> OK, I will have to go to our shops again and look around. Most stuff was the fluffy kind rather than rigid. Maybe I overlooked it.
> 
> 
> Did I miss the part in Ethan's text where to place the absorbers? By the way, Ethan, very nice work! Now I just need to find the German fibreglass stuff that corresponds to 703 and need to know where to hang the absorbers.



Search the web for a Knauf dealer and ask them to order you Knauf Black Acoustical Board . Sound absorption coefficients are at the bottom of the page, but I would definitely recommend the 2" product.


If I remember correctly you need to buy a minimum of one carton (six sheets). Each sheet is 2' x 4' - so you'll get 48 sq. ft. of coverage. I would expect to pay around $300 per carton, but its been a while since I ordered any and building materials have skyrocketed in price so I tried to build that into my estimate.


They also sell some very absorptive Insulation Board - so find a local dealer and price it out. This stuff will require you put some fabric around it to give it a clean look, the black stuff looks pretty sharp framed with some cheap molding.


Of course you can just order nice looking absorbers over at realtraps.com, but this is definitely an option.


----------



## dreamhost

This is my first post reguarding acoustical treatments so please be kind, I really am quite new to this area.


About 6 months ago I moved from a condo to a home where I have no worries about sound levels anymore. Finally I can do anything I like with the rooms. Until the weather gets nicer outside I have moved my 'theater' into a small 12x11 room. It's somewhat crowded but ok for 2 people to watch movies or 1 person to listen to music, very small sweetspot.


After spending the last month really tweaking out the htpc side of things I finally have a decent source for music, but that's another story. The problem I have now, is things seem to 'ring' when at fairly high volumes. I don't know how else to explain it, but I really believe I can hear a slight ringing in my ears and it's really taking away from the effect I am trying to achieve.


This problem is why I am making the post in this forum. As the room serves multiple purposes I can't do much with the position of equipment or furniture, it's also my office.


Here is a picture of the front wall









It is about 8.5' before getting to the door on the right side.

The curtains on the left side are double doors going out to the balcony. They take up about 1/2 of the side wall.

What I was thinking about was using some kind of treatment on the wall below the screen, just need to know what would work best there. I really can't move the speakers further out into the room, as it's quite shallow to begin with, can go a few more inches if needed. From the picture you can see that I have run all the wires for the speakers through the walls to the server closet.


Would building panels with the 703 stuff that I read about on here, that take up the entire bottom portion of the wall, below screen, help here?


Here is the rear wall









There is about 6-8" between the wall and the seats when reclined. Curtains cover up a window, just have not gotten around to cutting the curtains down yet.

Rear speaker will be placed on a shelf up where the backplate is located. Problem I ran into is the corners are not square so I could not use 'off the rack' corner shelves, yeah really sucks....


I was thinking about using the same 703 stuff below a 'chair rail' level, though not sure if that would help. Should I also put some panels up above the chairs?


Here is the side wall with the desk









Same problem with rear speaker, walls not being square. No idea at all what to do in this part of the room. The first door on the left goes to the 'server closet' that holds all the gear including computers. Far left door is exit to the room.


Also not sure what to do reguarding bass traps in the room. It's already quite crowded, but could use something for sure.


I am open to any advice here as I am not sure where to start this project, and it's been sitting like this for a few months now. Definately time to kick it in gear.


As to equipment I am using the following

infocus 7210

monitor audio gr 10's x4

I have 2 gr60's that I put in the bedroom for now as it was overkill for such small room, though with treatments I hope to bring them back.

Velodyne dls

sunfire mkII

denon 5800

denon 3910

htpc with hd setup


----------



## eugovector




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> This is my first post reguarding acoustical treatments so please be kind, I really am quite new to this area.
> 
> 
> About 6 months ago I moved from a condo to a home where I have no worries about sound levels anymore. Finally I can do anything I like with the rooms. Until the weather gets nicer outside I have moved my 'theater' into a small 12x11 room. It's somewhat crowded but ok for 2 people to watch movies or 1 person to listen to music, very small sweetspot.




If you could sketch up an overhead view, that would be helpful. I like "Room Arranger" for simplicity of use. Google it.


----------



## pepar

In replying to a post with big pics, unless your reply deals specifically with the pics, please consider deleting them from your reply as they scroll the thread onto the next page very quickly . . .


----------



## dreamhost




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> If you could sketch up an overhead view, that would be helpful. I like "Room Arranger" for simplicity of use. Google it.



Here it is









each square is 12 inches, room is almost exactly 12x11x8.5high I would have put text on each item but the program doesn't seem to allow it. Hope that between the diagram and the actual pics that it's clear what I am dealing with.


----------



## dreamhost




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> In replying to a post with big pics, unless your reply deals specifically with the pics, please consider deleting them from your reply as they scroll the thread onto the next page very quickly . . .



Not sure if you mean me....

If you do, yeah the pics are kinda important to describe what I am dealing with. It's so difficult to work and describe such a small room without them, esp with so much going on in such a small space.


I was able to track down a local dealer for the rigid fiberglass today. Pickup tomorrow. Only thing is not sure if to go with 1" or 2" 6lb or 7lb board insulation. I believe the brand was 'kanuff" spelling wrong I'm sure....


From what I gather in this very long thread, I may be better off going with 1" with a 1" space between the insulation and the wall vs. going with 2" flush mounted. As the stuff is only like $3/sq' I figure it's cheap enough that I can't loose either way. My biggest problem I see myself is that my first reflection points on the side walls both have doors there. One going to server closet, and the other is going to the balcony, covered by drapes. Expert advice on placement and types is def going to be needed in such a small room.


The first thing I want to tackle is the 'ringing' I hear at fairly loud volumes. It's not terrible but definately there. I would say it's in the upper middle range. I find myself getting fatigued listening to long in here, esp late night with jazz prior to bed, though I do listen to just about anything in here. I want a huge soundstage, well as big as possible for such a small room. I want the vocals to be crystal clear, and I really want to feel like I'm actually there. Of course everyone says that....


Afte that I'll tackle the bass. Believe it or not, it's not to bad, though there are definately some peaks and valleys in play. Esp around 40 and 80 hz. I was thinking about a softit in the back by the projector and turning it into a bass trap, if that would even work, no idea. Also as my rear walls are not square, hence the speakers still not mounted, I could use floor-ceiling corner traps with the speaker inside. Of course the side with the desk would only go from the desk up as not possible below desktop.


Well that's about all I can think of. I'll leave it up to the experts now.


----------



## pepar




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> Not sure if you mean me....



Nope, not you - you needed the pics. It was the next poster who has now edited his post and removed them.


----------



## eugovector




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> Here it is
> 
> 
> each square is 12 inches, room is almost exactly 12x11x8.5high I would have put text on each item but the program doesn't seem to allow it. Hope that between the diagram and the actual pics that it's clear what I am dealing with.



Well, seeing as how no one else has chimed in yet (thread must be getting a little stale)...


First, if you're using room arranger, the text is called "labels", in the object properties.



Between windows, doors, and your screen, you don't have a whole lot of wall left. Assuming you don't want to reorient the room 180 degrees, block out that window w/ your screen, and get rid of that desk, I suppose your positioning is about as good as it gets. You could center up the screen as much as possible, and move your right channel whenever you want to enter/exit the room, but I'm sure that will get old quick.


It looks like your seating is a little far back. Assuming you like your seating distance/screen size, I'd move your L/R out a bit to give them some breathing room, even up the distance between the seating position and your L/C/R, and give you a 45 degree listening angle.


That ringing is probably flutter echo, so you've got to damp your parallel surfaces.


Since your emphasis is is on the big sound stage (which, as the former owner of a 12x12x10 I can tell you is a losing battle): Put 2" over as much of the front wall as you can, spaced out 2" if you can. Get some sound reflective curtains for that back window (thick manmade fibers, even vinyl), and hang diffusors to the right and left of it. A couple tall bookcase paked with thrift store books would work on the cheap.


See where that gets you. If the ringing is still there, you'll need to add more diffusion/absorption, probably absorption. New carpet with a thick pad? More fiberglass?


Anyone else have thoughts?


----------



## dreamhost

Thank you eugovector for the input.


Your right about the placement of equipment/furniture. I tried just about everything I could think of prior to placing things where they are at now. This was the best scenario I could come up with.


I found a company that sells the 703/705 in both 1" and 2" thick panels. Will drive down tomorrow and pick up a bunch. From everything I have read in this thread and other sources I think I am going to go with the 1" 705 and space it 1" away from the wall. I'm initially going to start by covering the entire front wall below the screen with this. In the future I may rebuild my screen so that I can place it behind there as well.


As to the rear walls, I can probably go with corner traps from the desk to ceiling on the left side, and floor to ceiling on the opposite side. Seems concensis is to use 705 for the bass traps. I may even have enough room between the bass traps to place a small 2x6 705 panel on the back corners and rear windows.


the hardest part has been figuring out which materials to go with for the panels, and wether or not to purchase it with facing or without.


Another idea I had was to build a triangle bass trap along the front wall ceiling all the way across the room. I can't go an entire 2' triangle but could probably come close to 16" or so. Heck it may even look kind of cool, who knows.


Curious if I should do any treatment on the side walls at all. As the reflection points both have doors there, one wall being my closet, and the other being the balcony doors, there is no way to properly place panels. I can easily put them further toward the back of the room on the side walls though. Just not sure if it would have any effect at all, or if it would harm the sound.


I don't want to kill the room, dead, but it does need to be toned down. It's just as important to me to maintain a semblance of a soundstage as well.


If I'm barking up the wrong tree, or going to far with ideas, please let me know.


----------



## dreamhost

Well I ran out today and purchased 50 of the 2x4 2" 6lb '705' panels to see if they would help out or not. Wish they had at least some 1" in stock but no luck there so I bought what I could get my hands on.


I figured that before taking the time to build/stain and cover the panels that I would try setting them around the room first to see if they made any difference. First I started by placing 8 panels around the room, listened for awhile, wasn't exactly blown away by the change so I made some changes.


I read about people cutting them into triangles and stacking them into a corner. So a few hrs later I had one big pile ready. Really only having one corner in the room available I decided to start there.









The sound change wasn't really all that evident. I wonder If I should continue all the way up the wall or not. Takes a lot of time and energy cutting these suckers, so if people here believe it wont help I'd like to hear before going through the motions.


If it is worth it, was thinking about leaving the rear speaker there, filling in the sides, and just continuing up the wall until I reach the ceiling. Of course if it does sound better, then I will build enclosers and wrap them to make it look right.


I also tried laying a few across the front to see if there was an effect









I may only be imagining things but it does seem to help a little bit with the harshness. It's not a huge change like I was hoping for, but there is a little.


Also, do you guys think it would help if I rebuilt my screen so that I could place this stuff behind it as well?


If I can find a scenario where this stuff really helps the room out, then I will build 1x2 frames for them, router edges, and stain them, probably deep mohogany. Will use french cleats on the back so that they are sticking about an inch out from the walls.


As I'm not getting many replies I just wanted to show that I'm serious about trying this, and doing everything I can think of from reading the threads. Any expert advice is GREATLY appreciated.


----------



## eugovector

50 panels? Good God!! what did that run you. I only bought 12 of the 703 for $120, and I thougt that was a good deal. Are you getting this stuff really cheap?


Before we go any further, please be careful when cutting and stacking that fiberglass. If you get a bunch of those fibers in your lungs you're not going to like it. It won't kill you, but you're not going to like it.


I'm not sure what you mean by staining the fiberglass. I framed mine and covered it with a thin, natural fiber (cotton) fabric. Check out the walmart bargin shelf. You can also affix it directly to the panels w/ 3m spray adhesive.


On to the room. First you should understand what you're doing, and how sound works. With the fiberglass in the corner, you are taming room modes. Google that one if you're not familiar with it. Fiberglass in the corner will smooth out bass a little, should help shorten bass reverb time a bit. With as much fiberglass as you have, you might as well use the leftovers for this purpose.


One of your original problems was flutter echo. If you clap your hands, and you get a pringy reverb, this is flutter echo. It's cause by sound bouncing back and for between parallel surfaces, so anywhere you have 2 flat, reflective surfaces, you want to hang fiberglass on atleast one of those surfaces. Like I recomended, the front wall should be as dead as possible. Given that your room is so small and you have that screen taking up a lot of your front wall, you'll want to deaden or diffuse the first reflection points on the back wall, the space right behind your ears.


Putting fiberglass behind your screen won't do a damn thing unless your screen is perforated, or otherwise acoustically trandparent.


What to listen for? Do a clap test, then hang your fiberglass, then repeat the clap test. The results should be quite evident. That same improvement will carry over to music and movies. Dialogue should be clearer. You should be able to hear quiet details in music that were masked by room reverb before. All of these things I notice after hanging only 9 2x4 2" 703 panels in my 15.2x13.8x8 room.


If you feel the room is too dead. Take down a panel or two from the side or back walls. Like that better? Then hang the panels you just took down in another room, or make super chunk bass traps out of them.




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> Well I ran out today and purchased 50 of the 2x4 2" 6lb '705' panels to see if they would help out or not. Wish they had at least some 1" in stock but no luck there so I bought what I could get my hands on.
> 
> 
> I figured that before taking the time to build/stain and cover the panels that I would try setting them around the room first to see if they made any difference. First I started by placing 8 panels around the room, listened for awhile, wasn't exactly blown away by the change so I made some changes.
> 
> 
> I read about people cutting them into triangles and stacking them into a corner. So a few hrs later I had one big pile ready. Really only having one corner in the room available I decided to start there.
> 
> 
> The sound change wasn't really all that evident. I wonder If I should continue all the way up the wall or not. Takes a lot of time and energy cutting these suckers, so if people here believe it wont help I'd like to hear before going through the motions.
> 
> 
> If it is worth it, was thinking about leaving the rear speaker there, filling in the sides, and just continuing up the wall until I reach the ceiling. Of course if it does sound better, then I will build enclosers and wrap them to make it look right.
> 
> 
> I also tried laying a few across the front to see if there was an effect
> 
> 
> I may only be imagining things but it does seem to help a little bit with the harshness. It's not a huge change like I was hoping for, but there is a little.
> 
> 
> Also, do you guys think it would help if I rebuilt my screen so that I could place this stuff behind it as well?
> 
> 
> If I can find a scenario where this stuff really helps the room out, then I will build 1x2 frames for them, router edges, and stain them, probably deep mohogany. Will use french cleats on the back so that they are sticking about an inch out from the walls.
> 
> 
> As I'm not getting many replies I just wanted to show that I'm serious about trying this, and doing everything I can think of from reading the threads. Any expert advice is GREATLY appreciated.


----------



## eugovector

Dreamhost,


Just read your other thread. Since you don't seem to be afraid of throwing a little money at a problem, and you mention boominess, take out what your bass traps can't help with the Behringer FBD and Room EQ Wizard. Google it.


----------



## dreamhost




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> 50 panels? Good God!! what did that run you. I only bought 12 of the 703 for $120, and I thougt that was a good deal. Are you getting this stuff really cheap?
> 
> 
> Before we go any further, please be careful when cutting and stacking that fiberglass. If you get a bunch of those fibers in your lungs you're not going to like it. It won't kill you, but you're not going to like it.
> 
> 
> I'm not sure what you mean by staining the fiberglass. I framed mine and covered it with a thin, natural fiber (cotton) fabric. Check out the walmart bargin shelf. You can also affix it directly to the panels w/ 3m spray adhesive.
> 
> 
> On to the room. First you should understand what you're doing, and how sound works. With the fiberglass in the corner, you are taming room modes. Google that one if you're not familiar with it. Fiberglass in the corner will smooth out bass a little, should help shorten bass reverb time a bit. With as much fiberglass as you have, you might as well use the leftovers for this purpose.
> 
> 
> One of your original problems was flutter echo. If you clap your hands, and you get a pringy reverb, this is flutter echo. It's cause by sound bouncing back and for between parallel surfaces, so anywhere you have 2 flat, reflective surfaces, you want to hang fiberglass on atleast one of those surfaces. Like I recomended, the front wall should be as dead as possible. Given that your room is so small and you have that screen taking up a lot of your front wall, you'll want to deaden or diffuse the first reflection points on the back wall, the space right behind your ears.
> 
> 
> Putting fiberglass behind your screen won't do a damn thing unless your screen is perforated, or otherwise acoustically trandparent.
> 
> 
> What to listen for? Do a clap test, then hang your fiberglass, then repeat the clap test. The results should be quite evident. That same improvement will carry over to music and movies. Dialogue should be clearer. You should be able to hear quiet details in music that were masked by room reverb before. All of these things I notice after hanging only 9 2x4 2" 703 panels in my 15.2x13.8x8 room.
> 
> 
> If you feel the room is too dead. Take down a panel or two from the side or back walls. Like that better? Then hang the panels you just took down in another room, or make super chunk bass traps out of them.



Panels were just under $20 each, so not to bad. I got them somewhat local, 50 mile drive, so no shipping involved. They didn't have any 703 in stock, only had 2" 705 so I bought what they had.


Your right about the lungs. Took long cold shower to stop the itching, totally sucked, and I've only just begun.


Do you think continuing the corner trap all the way to the ceiling would help? I was going to leave the rear speaker where it's at and just continue adding 705 above it. Just got tired of cutting this stuff. Will continue it up this weekend if it's advised. I just wish I could do the other corners. I do have enough that I could do the entire ceiling circ like I did the corner, though I have never seen that done before.


I am NOT going to leave it as is. If I like the effect I was trying to say that I would build enclosures for all the 705, and stain the enclosure itself where you would see the wood boarders. Think speaker cabinet with cloth grill, only the cloth would cover the 705. I want to keep this room looking as nice as possible.


So far I have noticed a substantial increase in perceived bass in the room. I literally jumped up to turn off the buttkickers, only to find they were already off. The room is still a bit boomy, but it's def tighter.


I put two large panels on the front wall below the screen, temp covered in fabric just sitting there, and it has indeed cleared up the front stage. Hands down the biggest difference though was putting a sheet on top of the coffee table. I was cutting it there, and noticed sound was kinda cool, so sat back and wow..... big difference.


Even without treating the side walls, the harshness is now gone, or close to it. I'm certain that I am pushing such a small room beyond it's volume capability. I'll keep bringing in pieces and putting them around the room until I find a level I like. Then I'll build the frames etc.


Question about framing the panels:

As I have 2" I know that I still want an airgap between the panel and the wall, prob close to an inch. Now if I use wood that is 3" wide and have the panel in the front part, that leaves the back 1" open, but the sides of the wood would be touching the walls. Is that optimal?

Or should I just build the frame 2" thick and then th 705 would fill it up, and then just use a crossbrace french cleat to keep it away from the wall?

Hope this makes sense.... photoshop is not on this computer so can't diagram it out to well.


----------



## dreamhost




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Dreamhost,
> 
> 
> Just read your other thread. Since you don't seem to be afraid of throwing a little money at a problem, and you mention boominess, take out what your bass traps can't help with the Behringer FBD and Room EQ Wizard. Google it.



Should I go that route, or just purchase a Audyssey setup? It's only $2500 plus install, so not talking a ton of $ here. Never heard of the Behringer FBD before.


----------



## Tukkis




> Quote:
> Should I go that route, or just purchase a Audyssey setup? It's only $2500 plus install, so not talking a ton of $ here. Never heard of the Behringer FBD before.



Honestly, if you're willing to spend that type of money I would go ahead and contact Terry from HAA.


He's a specialist and can not only recommend good treatments but also back it up with graphs etc. to show you the difference.


----------



## eugovector




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> Should I go that route, or just purchase a Audyssey setup? It's only $2500 plus install, so not talking a ton of $ here. Never heard of the Behringer FBD before.



Dude, I need your problems for a day.


Yeah, you've already spent $1000 on fiberglass. Just hire somebody.


----------



## bpape

Eugo.


What you've done and heard only a little improvement is simply because there just isn't enough there yet. Doing half of one room corner isn't going to give a significant improvement in bass control For what you're doing, save some money and use 703 instead of 705 - will work just fine in a solid chunk like that.


As for the front wall, you need to do the whole thing. It's not just boundary effects but also killing surround reflections off the front wall mucking things up.


Bryan


----------



## dreamhost




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Eugo.
> 
> 
> What you've done and heard only a little improvement is simply because there just isn't enough there yet. Doing half of one room corner isn't going to give a significant improvement in bass control For what you're doing, save some money and use 703 instead of 705 - will work just fine in a solid chunk like that.
> 
> 
> As for the front wall, you need to do the whole thing. It's not just boundary effects but also killing surround reflections off the front wall mucking things up.
> 
> 
> Bryan



No go on the 703 as I already have all the 705 I would ever need.

As to having only done 1/2 of 1 corner, do you think it would be more effective to carry that all the way to the ceiling? As the room is so small that would equate to about 1.5% of the entire room volume.


I'm going out today to pickup a mic adaptor so that I can take some frequency sweeps of the room. I'm curious if there is a formula involved with bass traps and how much vs. density to help with the problem tones? MEaning that if I have a hole at say 80hz, is there a formula to follow that tells me exactly how much of the 705 to use and where and in what configuration? Obviosly I am quite new to this acoustic stuff but eager to learn.


----------



## chinaclipper

...I have all the pieces, the Lincoustics, the poly batting, and the furring strips, etc.


I have 84" high ceilings.


I have heard 1/2 way up from floor is Lincoustic, remainder is poly batting.


Question: I am rather tall, can I extend the lincoustic to 48 inches? Remainder finished with poly batting of course.

Reasoning-Lincoustics comes in 48" rolls. one less cut...










I plan on putting the chair rail moulding about 1/3 of the distance from floor-ie black GOM lower ~1/3, burgundy GOM ~ upper 2/3.


Question: Will that make the walls look weird if the moulding is not located at the lincoustic/poly batting seam?


Won't the 1" furring strips elimate this wierd interface?


Thanks for the advice,

Best,

Tom

Chinaclipper


----------



## rockemsockem

This weekend, I will be making (2) 36" x 18" x 4" panels to mount in the corners of my room.


They will be wrapped in batting, and covered with Burlap across the front. They will not have frames of any kind. But I can attach small wood strips if needed.


Does anyone have any ideas on how I can mount them straddling the upper corners?


See pics attached.




















Thanks


----------



## Terry Montlick




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> I'm curious if there is a formula involved with bass traps and how much vs. density to help with the problem tones? MEaning that if I have a hole at say 80hz, is there a formula to follow that tells me exactly how much of the 705 to use and where and in what configuration? Obviosly I am quite new to this acoustic stuff but eager to learn.



Unfortunately, no. But your speakers are so close to one wall and your chairs so close to another, I can't imagine *not* having some significant acoustical issues. Boundary interference effects are strongest under these circumstances, as are room mode peaks.


I would start by putting the 2" fiberglass over all of the wall right behind the seating, and over all of the wall behind speakers and screen. Putting fiberglass behind your screen will only affect low frequencies, but you say you have problems in this area. Flutter echo is a higher frequency phenomenon, and can only occur when you have parallel surfaces *with both you and the sound source between them*. Since your speakers are below the screen, there can't be any audible flutter echo between the screen and the back wall.


Regards,

Terry


----------



## eugovector




> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> As to having only done 1/2 of 1 corner, do you think it would be more effective to carry that all the way to the ceiling?



Yes.



> Quote:
> Originally Posted by *dreamhost* /forum/post/0
> 
> 
> I'm curious if there is a formula involved with bass traps and how much vs. density to help with the problem tones? MEaning that if I have a hole at say 80hz, is there a formula to follow that tells me exactly how much of the 705 to use and where and in what configuration? Obviosly I am quite new to this acoustic stuff but eager to learn.



No, no formula. IF you are eager to learn, you should read this whole thread, as well as Ethan's FAQ and the information on Room EQ Wizard, The Behringer BFD, and and anything else that googling "acoustic treatment" and "Room Acoustics" turns up.



Look before you leap.


----------



## Ethan Winer




> Quote:
> Originally Posted by *rockemsockem* /forum/post/0
> 
> 
> Does anyone have any ideas on how I can mount them straddling the upper corners?



That's always a tough one. Maybe long picture wire or nylon fishing line? Of course, that's the whole point of DIY - the fun of figuring out what to do and how to do it.


--Ethan


----------



## BasementBob

rockemsockem:



> Quote:
> Does anyone have any ideas on how I can mount them straddling the upper corners?



There's a few ways. There's some ideas in this thread .


----------



## ineluki

My house building is about to start. My media room is 3.5 x 5.9m.


I was hoping to have a multipurpose/minimalist room with stealthed equipment, stealthed motorized screen, etc. So is there any way to improve the room for both 2ch and surround without it looking like a dedicated room? Is it even possible to improve the sound to a certain extent for both 2ch and surround or is any benefit for one a hinderance to the oher?


I can always move my 2ch setup into a different room so what are the best "bang for the buck" treatments I can do for surround without doing large parts of the room?


----------



## myfipie




> Quote:
> Originally Posted by *ineluki* /forum/post/0
> 
> 
> My house building is about to start. My media room is 3.5 x 5.9m.
> 
> 
> I was hoping to have a multipurpose/minimalist room with stealthed equipment, stealthed motorized screen, etc. So is there any way to improve the room for both 2ch and surround without it looking like a dedicated room? Is it even possible to improve the sound to a certain extent for both 2ch and surround or is any benefit for one a hinderance to the oher?
> 
> 
> I can always move my 2ch setup into a different room so what are the best "bang for the buck" treatments I can do for surround without doing large parts of the room?



The more bass traps you put into the room the flatter the response will be. Most rooms are going to take quite a few bass traps to get it to a point of "HEAVEN", but there is no reason why starting with 4 bass traps with one in each corner and panels for the first reflection points will not help a lot.


Glenn


----------



## Ethan Winer




> Quote:
> Originally Posted by *ineluki* /forum/post/0
> 
> 
> what are the best "bang for the buck" treatments I can do for surround without doing large parts of the room?



There's no good answer. As Glenn said, even four bass traps, one in each wall-wall corner, will help. But if your goal is truly excellent sound you'll need a lot of acoustic treatment. There's no way around that.


You can hide treatments behind faux fabric walls etc, but it's more expensive. So you have to balance cost, appearance, and audio quality. Personally, I don't mind the look of acoustic treatment. I think it looks cool! And when you dim the lights to watch a movie or listen to a great CD, how many panels you see is irrelevant.


--Ethan


----------



## pmeyer

By the way, does anybody have good suggestions for modelling corner bass traps in a program like CARA?


CARA works on the concept of surfaces with absorption coefficients applied to each area of the surface. I can easily model the angled front of the corner trap as the new wall surface, but what absorption coefficient would I apply across it's face? In reality, it seems like the absorption would actually vary across the face (more bass absorption in the middle, where it's deeper).


Has anyone measured/estimated the average absorption coefficient equivalent across the front surface of a superchunk style corner bass trap?


----------



## grprez81121

I finally made it to the end of this Thread. I now have enough information to be dangerous. I would like to thank Dennis, Ethan, Terry, pepar,BasementBob and bpape. I hope to complete my theatre in the next 90 days. I will be posting questions as we proceed.


Thanks

Guy


----------



## Glenn Baumann

Dennis, Ethan, Terry, pepar, BasementBob, bpape and others I really need some input...





I was not sure whether or not to post here in the Acoustical Treatment thread and after consideration I felt that this issue would in all probability full under acoustic treatment... so here goes...


I have a theater room that I would consider Quasi- dedicated as there is an opening through a wall into another room and I will also ultimately be acoustically treating this room to some degree with the requisite first reflection and bass absorption treatments.


The theater room is 12.5 ft. wide and 21 ft. long with a shed type slanted ceiling which rises from an 8 ft high wall on the right to a 10 ft. high wall on the left. The theater room has a 5 ft. wide X 3 ft. high opening which is centered on the left wall and is 3.5 ft. off the floor and opens into a 8 ft. wide X 11 ft. long galley style kitchen.


There is also a 5 ft. wide X 3.5 ft. high glass window centered on the right side wall opposite the left side wall opening and has a blackout cellular shade installed running in light control tracks.


The two rooms can be completely sealed off from the rest of the house via doorways so in essence the two sealed rooms are only linked together via the 3 ft. X 5 ft. opening and I was wondering how to effectively handle and work with this opening and the opposing window?


Remember, I will ultimately be placing acoustic panels within the room to some degree and the window on the right side wall already has the cellular blackout shade installed.


Should I install some wooden blinds over the opening into the kitchen? Would this help contain some of the High/ Mid frequency sound and help in room acoustics?


Should I also place similar wooden blinds over the cellular shade treated glass window on the right side of the room for symmetry?


Basically, how is this opening on the left side of my theater going to possibly impact my in room acoustics and how should I deal with it?


Any and all suggestions will be greatly appreciated!



...Glenn


----------



## Terry Montlick




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> By the way, does anybody have good suggestions for modelling corner bass traps in a program like CARA?



CARA, or even an actual ray-tracer, will not produce correct results if you just plug in the geometry and absorption coefficients. The reason is that at low frequencies (where the size of the surface is comparable to or smaller than a wavelength) diffusion, in the sense of diffraction/scattering, will become a significant factor at the edges of the absorber. The simple ray model is no longer a correct description, because rays effectively bend into the absorber near boundaries. They are no longer straight. This causes the effective surface area to be significantly greater at low frequencies than geometric acoustics would predict.


Regards,

Terry


----------



## Terry Montlick

Glenn -- I am too stupid to visualize your room, even though you've given an extensive textual description.







Can you post some kind of diagram or plan?


Thanks,

Terry


----------



## pmeyer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> CARA, or even an actual ray-tracer, will not produce correct results if you just plug in the geometry and absorption coefficients.
> 
> ...
> 
> Regards,
> 
> Terry



Thanks, Terry, good input.


Is CARA completely useless below a certain frequency (say 200 Hz)? Or is it useful but it under/overestimates the effectiveness of bass traps? Is there a way to compensate? A rule of thumb for fudging the geometry or the coefficients up or down to roughly compensate for the edge effects/bending?


If not, I'll just plan on using CARA for higher frequency stuff: localization, speech intelligibility, etc. and drop in as many bass traps as the room can handle without looking too silly.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> Thanks, Terry, good input.
> 
> 
> Is CARA completely useless below a certain frequency (say 200 Hz)? Or is it useful but it under/overestimates the effectiveness of bass traps? Is there a way to compensate? A rule of thumb for fudging the geometry or the coefficients up or down to roughly compensate for the edge effects/bending?



CARA is one of two general classes of geometric acoustic modeling programs: image source modelers and ray tracers. CARA is an image source modeler. Professional programs are pure ray tracers or hybrids which use the image source technique for the first few reflections and ray tracing for the rest. More about this later.


With all geometric modelers, you have the absorption diffraction problem. I know of one technique to deal with it, which I developed myself. I started writing this up for a professional journal last year. But then I realized it is worth much more to me as trade secret who's use is part of what my clients pay for than as a journal paper. Sorry!



> Quote:
> If not, I'll just plan on using CARA for higher frequency stuff: localization, speech intelligibility, etc. and drop in as many bass traps as the room can handle without looking too silly.



There are many tricks of the trade which turn geometric modelers from amusing curiosities which draw pretty diagrams into useful prediction tools. One of the biggest issues is correct absorption coefficients. The "book values" measured in the lab simply don't cut it in many cases, and they have to be tuned through experience to reflect realistic field conditions. So its often a case of "garbage in -- garbage out."


Another issue which is particular to CARA is sufficient computation time to yield accurate results. An image source modeler is very efficient for purely rectangular rooms, and can yield results as good as any ray tracer for these. But add *any* more complex room geometry (furniture, for example), and the accuracy plummets for the same computation time. This is why professional programs don't use the pure image source technique.


So take the CARA results with a very large grain of salt. IMO, it is a good qualitative tool for interactively learning some of the effects which rooms have on sound. But as a serious prediction tool, it is lacking. Which is not to say that if you had a pro tool like ODEON, for example, you would necessarily get great results. The proper use of complex prediction software requires experience. There are elements of uncertainty, sensitivity to particular conditions, and interpretation which can take years to learn. If is somewhat akin to using a CAD architecture program. You can draw pretty buildings with it, but this does not automatically make you an architect!










Regards,

Terry


----------



## Ethan Winer

Glenn,


> I was wondering how to effectively handle and work with this opening and the opposing window? 
Should I install some wooden blinds over the opening into the kitchen? Would this help contain some of the High/ Mid frequency sound and help in room acoustics?


----------



## Glenn Baumann

Ethan,


Sound isolation between the two rooms is not an issue at all, I am speaking strictly in an acoustical sense.


I was curious as to any possible acoustical anomolies that might be created such as additional ringing, slap echo or a general break down in the acoustic bubble and or envelopment issues particularly on the left side of the room where the opening is into the kitchen.


My thinking was that maybe some wooden blinds installed over the opening might help contain and or allow some of the sound to bounce around the room a little better. If that strategy would help and in the interest of balance/symmetry I thought that maybe I should also install similar blinds over the cellular blackout shade treated window which is directly across the room on the opposing right side wall.


Remember, the 3 ft. X 5 ft. opening is on the left side of the room and the 3 ft. X 5 ft. window is directly opposite the opening on the right side wall like mirrors of each other... I hope that makes sense.


The total room length is 21 feet and the opening and window are about centered on the side walls. My 3 abreast theater seats are just within the back third of the room and when sitting upright my head is about 6 to 6.5 feet from the back wall.


A cursory examination appears to place the opening and window just behind the first side wall reflection point and I might be able to adjust that somewhat via seating and speaker placement changes.


I am probably reading to much into this, and I know of course that I should set everything up and listen and evaluate the sound before passing any real judgements! I am sure however that I will be installing room treatments in the form of first reflection/ broadband absorption and bass absorption as I do have some slap echo that I can hear and the room will definitely require some taming.



...Glenn


----------



## Ethan Winer

Glenn,


> My thinking was that maybe some wooden blinds installed over the opening might help contain and or allow some of the sound to bounce around the room a little better.


----------



## craig john

For an HT/MC Music Room, would it be a good idea to cover the entire front wall with 4" 703? Would this make a good bass trap? Or, would it be better to place the traps in the corner and use a thinner material, (1" or 2") on the rest of the wall? Which would provide more bass trapping?


Thanks.


Craig


----------



## cyberbri

The latter. Put the thicker stuff in corners and at room boundaries (straddling corners and places where floor/ceiling and walls meet), with thinner 2" panels at specific points arond the room. Don't cover every wall.


----------



## bpape

Agreed mostly.


How thick you go on certain parts of the front wall will depend on what you're needing to do in terms of SBIR control. For pure reflection control, 1-2" is fine.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> Agreed mostly.
> 
> 
> How thick you go on certain parts of the front wall will depend on what you're needing to do in terms of SBIR control. For pure reflection control, 1-2" is fine.
> 
> 
> Bryan



Should acoustical measurements be taken before the 2" - 4" decision is made? The front wall in question here is behind a false wall, so no aesthetics are harmed by doing whatever there. It was my recommendation to use 4" instead of 2" thinking that it may reduce the need for chunky-style traps in the listening/viewing are by reaching lower in frequencies absorbed. Is my thinking wrong? If so, why?


----------



## BasementBob

pepar:



> Quote:
> lower in frequencies



Please define 'low', in hz range, that you mean. (To me, when I write 'low', what I mean is the typical-HT-room-volume's modal problems range, which would be in the 15hz to 115hz.)


Then define the % increase in normal incidence absorbtion at 125hz (and lower) to 1khz, and % increase in diffuse absorption at 125hz to 1khz, of going from 2" to 4" mounted on the wall.


Then cost justify it, including mounting technique differences. This is all from a 'how good is it as an absorber' point of view, not from a is it needed for some-specific-room point of view.


(also remember the ITU/EBU rule "Early reflections are defined as reflections from boundary surfaces or other surfaces in the room which reach the listening area within the first 15 ms after the arrival of the direct sound. The levels of these reflections should be at least 10 dB below the level of the direct sound for all frequencies in the range 1 kHz to 8 kHz.")


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Please define 'low', in hz range, that you mean. (To me, when I write 'low', what I mean is the typical-HT-room-volume's modal problems range, which would be in the 15hz to 115hz.)



His room sounded tubby and to me that's 125Hz to 250Hz, maybe 300Hz. Note that I said "low*er* in frequency" not "low frequency."



> Quote:
> Then define the % increase in normal incidence absorbtion at 125hz (and lower) to 1khz, and % increase in diffuse absorption at 125hz to 1khz, of going from 2" to 4" mounted on the wall.



Incidence absorption? Is that different from plain ol' absorption?







Is is a straight calculation, e.g. 4" 703, plain, has ~5x the absorption (.84 vs .17) at 125Hz of 2" 703, plain?



> Quote:
> Then cost justify it, including mounting technique differences. This is all from a 'how good is it as an absorber' point of view, not from a is it needed for some-specific-room point of view.



I know what I paid for plain 2" 703, but I've never priced 4". If it was much more, then couldn't one simply use two layers of 2"? On your last sentence - huh?



> Quote:
> (also remember the ITU/EBU rule "Early reflections are defined as reflections from boundary surfaces or other surfaces in the room which reach the listening area within the first 15 ms after the arrival of the direct sound. The levels of these reflections should be at least 10 dB below the level of the direct sound for all frequencies in the range 1 kHz to 8 kHz.")



Wrong it may have been, but my thinking was that he'd get more absorption in the range that sounded, to me, like it was a problem.


----------



## BasementBob

pepar:


I'm just muttering in general terms -- not about any specific room.










'normal incidence' is an angle, in this case straight into the face. There aren't many published results about these. But there's a lot of theory, and calculation tools. ChrisW's spreadsheet for example.


'diffuse absorption' is sound coming from everywhere, and is the style for all the results at this page: http://www.bobgolds.com/AbsorptionCoefficients.htm 



> Quote:
> Wrong it may have been, but my thinking was that he'd get more absorption in the range that sounded, to me, like it was a problem.



You're not nessessarily wrong -- you may be 100% right. I was just hoping you'd make me some graphs of the expected difference between the two absorbers you're considering to see what you think the actual difference is between them.

I figure moving from 2" to 4" of 703 gives a

a) diffuse: 400% increase in diffuse absorption at 125hz, and a 20% increase in diffuse absorption at 250hz, and no increase above that frequency. (see bottom of graph)

b) normal: well, I'll do the graphs I was hoping for












> Quote:
> His room sounded tubby and to me that's 125Hz to 250Hz, maybe 300Hz. Note that I said "lower in frequency" not "low frequency."



Yep, I see a reasonable change in the 125hz to 300hz range moving from 2" to 4" in the normal and grazing and diffuse coefficients. (16000rayls/m may not represent 703, and neither may a computer simulation)


So, how many square feet of this do you think this specific room will need to make a perceptable difference? Where do you want to put it, and what side effects will it have?


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> pepar:
> 
> 
> I'm just muttering in general terms -- not about any specific room.



Roger that.







craig john and I have a specific room in mind.



> Quote:
> 'diffuse absorption' is sound coming from everywhere, and is the style for all the results at this page: http://www.bobgolds.com/AbsorptionCoefficients.htm



Roger that as well. (That's you, right, you're da Bob in bobgolds?)










> Quote:
> . . . what you think the actual difference is between them.
> 
> I figure moving from 2" to 4" of 703 gives a
> 
> diffuse: 400% increase in diffuse absorption at 125hz, and a 20% increase in diffuse absorption at 250hz, and no increase above that frequency.
> 
> 
> Yep, I see a reasonable change in the 125hz to 300hz range moving from 2" to 4" in the normal and grazing and diffuse coefficients. (16000rayls/m may not represent 703, and neither may a computer simulation)
> 
> 
> So, how many square feet of this do you think this specific room will need to make a perceptable difference? Where do you want to put it, and what side effects will it have?



Thanks, and that's exactly what I had in mind. The "where" is behind his false wall. Can you point me to information and/or calculations for determining in advance how much it would take to make a perceptible difference and what "side effect" it would have? (I suppose I should be looking for _negative_ side effects?)


----------



## BasementBob

Perceptable

a) changing any reflection at some frequency band by 6db

b) halving RT60 at some frequency band

c) increasing the absorption in some frequency band by 30%


There's lots of side effects. One, from an RT60 perspective would be that if the room sounds good now with little absorption (no draps, no cloth couch, no carpet), and you cover an otherwise bare front wall with absorption that does a much larger job of absorbing 500hz to 8khz, than it does from 15 hz to 300 hz, you might create more problems than cures.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Perceptable
> 
> a) changing any reflection at some frequency band by 6db
> 
> b) halving RT60 at some frequency band
> 
> c) increasing the absorption in some frequency band by 30%
> 
> 
> There's lots of side effects. One, from an RT60 perspective would be that if the room sounds good now with little absorption (no draps, no cloth couch, no carpet), and you cover an otherwise bare front wall with absorption that does a much larger job of absorbing 500hz to 8khz, than it does from 15 hz to 300 hz, you might create more problems than cures.



Right now, it does not sound good. There's carpet and a large comfy sectional, but otherwise it is plaster walls and ceiling.


Here is a pic of my J-M Linacoustic-lined false wall cavity - http://www.peparsplace.com/assets/images/HT_009.jpg . My room sounds good, but I need to add traps to control the 125Hz to 250Hz range. I would have lost no more mids and highs by using 4" in my false wall cavity instead of the 2" I did use and I'd have less of a problem - or maybe NO problem - in that range. That is what's at the root of my thinking.


----------



## bpape

"Should acoustical measurements be taken before the 2" - 4" decision is made? The front wall in question here is behind a false wall, so no aesthetics are harmed by doing whatever there. It was my recommendation to use 4" instead of 2" thinking that it may reduce the need for chunky-style traps in the listening/viewing are by reaching lower in frequencies absorbed. Is my thinking wrong? If so, why?"


Yes. IMO we set up speakers and tweak location to get the smoothest response. Then based on what's left and what's being reinforced by SBIR, we deal with it accordingly. This is more of an iterative way to go about it but it works well in real rooms where there isn't always enough space to do what we'd like.


If we could get by with just 4" on the front wall and that was all that was needed, you'd be correct - assuming that you're not making the SBIR issues worse. You may in fact not WANT to deal with the really lower frequencies as they're already relatively flat in which case we'd go thinner. Also, the corners provide better efficiency over a number of different axial, tangential, and oblique modes where the front wall is going to deal with less of those and less efficiently.


Bryan


----------



## BasementBob

pepar:


One should define 'sounds good' a bit better.


For example

I had my room like this









and when I played the end credits to We Were Soldiers DVD, with the men's choir, I was in acoustic heaven. Room support was fantastic. I litterally stopped what I was doing and couldn't stop listening. I played that bit over and over, turned the volume up, showed that bit to all of my friends and relatives. It was fantastic. Easilly the best sound I've ever heard, anywhere.


But that layout wasn't what I wanted.

And the imaging was off and speach inteligibility seemed low.


I tried different speaker positions and treatment layouts.





























and although the last one above sounded really great,

what I ended up building was a little different:











That's 4" thick rockwool, with a 4" airgap behind it.

And I can tell you without a shadow of a doubt, it's not that heavenly room support I had before. It's dull and lifeless.


(for more about this and some more detailed acoustic observations regarding each picture please see
http://www.bobgolds.com/LivingRoomPl...ction/home.htm 

at 2006/12/01 about 60% of the way down)


Speach inteligibility is pretty good though.


I had some imaging problems, pod race from Star Wars I couldn't tell left from right. Room geometry takes care of left speaker off the left wall, and right speaker off the right wall. But the problem turned ot to be left speaker off right wall, which a right side wall absorber took care of and solved the imaging. Pod race is better with good imaging.


I've been meaning to do some ETF tests and tweaks, but I haven't gotten around to it.


That room will never be optimal acoustically due to other constraints -- and I haven't tried more or less surface area, nor more or less absorbtive material, in that front wall yet. Although I built it so I could fiddle.



A year ago I had the same speakers in the basement (five concrete surfaces walls and floor) and even with two subwoofers never had any bass. Upstairs in the living room (above pictures) I've got bass to burn. I'm hearing things I've never heard before and really enjoying them.



My point is 'sounds good' can actually be a bad thing.


With my lifeless room now, I've tried a bunch of the DSP modes on my receiver (DSP pretend to be a church, DSP pretend to be a concert hall, DSP pretend to be a rock studio, ...) and I've found that while I can get some of that heavenly sound with that particular spot in We Were Soldiers (although not nearly the stop dead in your tracks as if you've fallen under a spell like the first time you fall in love and think that all's right in the world that I had with the two other layouts), if I leave that DSP setting on there's some DVDs that I can't understand speach with -- but I turn off the DSP modes (output 'STRAIGHT') and it clears up immediately.


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> If we could get by with just 4" on the front wall and that was all that was needed, you'd be correct - assuming that you're not making the SBIR issues worse. You may in fact not WANT to deal with the really lower frequencies as they're already relatively flat in which case we'd go thinner. Also, the corners provide better efficiency over a number of different axial, tangential, and oblique modes where the front wall is going to deal with less of those and less efficiently.



OK, that gets my attention; thicker on a wall isn't as effective as corners. So that is a point in favor of saving money on 2" on the front wall and spending it on more effective corner treatments. In fact, that is probably the tipping point in favor of that.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> pepar:
> 
> 
> One should define 'sounds good' a bit better.



I have nearfield listening at all six listening positions. Once I tame the under 300Hz range, I will be a happy camper. So, actually, I misspoke. The room doesn't sound good, the _system_ does, and the room is not in the way.



> Quote:
> I had my room like this and when I played the end credits to We Were Soldiers DVD, with the men's choir, I was in acoustic heaven. Room support was fantastic. I litterally stopped what I was doing and couldn't stop listening. I played that bit over and over, turned the volume up, showed that bit to all of my friends and relatives. It was fantastic. Easilly the best sound I've ever heard, anywhere.
> 
> 
> But that layout wasn't what I wanted. And the imaging was off and speach inteligibility seemed low.



Not sure what you mean by "room support." And in light of poor imaging and low intelligibility, it's obvious your room's _support_ was interfering. Perhaps the room's signature was complementary to a choir, but not other sounds. This is exactly why I prefer nearfield listening.



> Quote:
> I tried different speaker positions and treatment layouts. and although the last one above sounded really great, what I ended up building was a little different:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> That's 4" thick rockwool, with a 4" airgap behind it.
> 
> And I can tell you without a shadow of a doubt, it's not that heavenly room support I had before. It's dull and lifeless. Speach inteligibility is pretty good though.
> 
> 
> I had some imaging problems, pod race from Star Wars I couldn't tell left from right. Room geometry takes care of left speaker off the left wall, and right speaker off the right wall. But the problem turned ot to be left speaker off right wall, which a right side wall absorber took care of and solved the imaging. Pod race is better with good imaging.
> 
> 
> I've been meaning to do some ETF tests and tweaks, but I haven't gotten around to it.
> 
> 
> That room will never be optimal acoustically due to other constraints -- and I haven't tried more or less surface area, nor more or less absorbtive material, in that front wall yet. Although I built it so I could fiddle.
> 
> 
> 
> A year ago I had the same speakers in the basement (five concrete surfaces walls and floor) and even with two subwoofers never had any bass. Upstairs in the living room (above pictures) I've got bass to burn. I'm hearing things I've never heard before and really enjoying them.
> 
> 
> 
> My point is 'sounds good' can actually be a bad thing.



To the extent that a room has a noticeable "sound" at all, yes. See my response above.



> Quote:
> With my lifeless room now, I've tried a bunch of the DSP modes on my receiver (DSP pretend to be a church, DSP pretend to be a concert hall, DSP pretend to be a rock studio, ...) and I've found that while I can get some of that heavenly sound with that particular spot in We Were Soldiers (although not nearly the stop dead in your tracks as if you've fallen under a spell like the first time you fall in love and think that all's right in the world that I had with the two other layouts), if I leave that DSP setting on there's some DVDs that I can't understand speach with -- but I turn off the DSP modes (output 'STRAIGHT') and it clears up immediately.



DSP, IMO, is worse than worthless. Artists, engineers and producers go to great length to create an ambiance. Monkeying with that can only degrade what the creators intended. If a particular DSP setting, or room environment, enhances a particular recording - We Were Soldiers for example - but nothing else, then it is likely that We Were Solders is not "right" either.


----------



## daxhughes

Dennis, Ehtan, and anyone else


I am doing a Ht room and i line around Memphis, TN. I have the room sheetrocked and want to get the acoustics right. My room is small 10 (width)x16 (length)x8.5(height). My room "T''s out in the back to 25 foot wide for about 4 feet.


I will sit around 12 feet from the front and thus 4 feet from the back.


Here are my thoughts:


1) Acoustic panels behind the front left and right placed on the sheetrock.

2) Acoustic panels atthe first reflective points (using mirror suggestion)

3) Basss traps in the corners in the front and in the back corners (the room is shaped in a "T" shape. SHould I put bass traps in the corbers created by the "T" as well.

4) Should i consider diffusors on the back walls or acoustic shields for absorbtion.


I mentioned where i live in case you could recommend someone locally I could have come and help me.


It seems that acoustic shields behind the front speakers is very important as well as shields at the first reflective points in relation to where the listener is sitting.


thanks for the help!


Dax


----------



## Ethan Winer

Dax,


> Here are my thoughts: 
I mentioned where i live in case you could recommend someone locally I could have come and help me.


----------



## Terry Montlick

Re: cost of diffusers, you can make inexpensive polycylindrical diffusers out of bent sheets of practically anything hard and relatively flexible. They are as good as the modern "well-type" diffuser in nearly all situations.


Both types of diffusers have the drawback of needing a lot of depth -- much more than an absorber of equivalent frequency effectiveness.


- Terry


----------



## davestern




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> I would not use the 2" material...it will very likely be too absorptive.
> 
> 
> The fill out is polyester batting. Don't use styrofoam.




Dennis, you sound pretty firm on not using styrofoam. Is there a valid reason, if it is fire rated.


----------



## nirvana_av




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Re: cost of diffusers, you can make inexpensive polycylindrical diffusers out of bent sheets of practically anything hard and relatively flexible. They are as good as the modern "well-type" diffuser in nearly all situations.
> 
> 
> Both types of diffusers have the drawback of needing a lot of depth -- much more than an absorber of equivalent frequency effectiveness.
> 
> 
> - Terry



Terry,


Can you offer any pointers on building "bent-sheet" diffusers such as what radius of curvature is needed to be effective and what the orientation of the arc should be?


----------



## daxhughes

I have my theater room sheetrocked and painted. Almost my whole front wall will be covered with the screen.


I keep hearing that shielding the front wall is big but what about my situation?


Should I treat all the areas around the screen or go ahead and treat behind the screen as well?


What should I use? Anything I can get at Lowes or Home Depot? Can I paint it to match the other walls in my theater room (brown).


I was goign to put acoustic shields right behind the front, left, and center channels. Would this not be enough treatment for my front wall.


The dimension are 9.5'wideX16'long.


Thanks for your advice


----------



## eugovector




> Quote:
> Originally Posted by *daxhughes* /forum/post/0
> 
> 
> I have my theater room sheetrocked and painted. Almost my whole front wall will be covered with the screen.
> 
> 
> I keep hearing that shielding the front wall is big but what about my situation?
> 
> 
> Should I treat all the areas around the screen or go ahead and treat behind the screen as well?
> 
> 
> What should I use? Anything I can get at Lowes or Home Depot? Can I paint it to match the other walls in my theater room (brown).
> 
> 
> I was goign to put acoustic shields right behind the front, left, and center channels. Would this not be enough treatment for my front wall.
> 
> 
> The dimension are 9.5'wideX16'long.
> 
> 
> Thanks for your advice



Start by reading this whole thread. This question has been asked and answered severall times.


Short version:


What about your situation?

Depends on if your screen is perforated.

OC 703 or similar. No. No.


----------



## daxhughes

i have read all the thread but i still am confused on how I am going to treat my front wall that has a non-perforated screen that takes up most of that front wall.


Should I go ahead and put OC 703 on the whole wall ebfore my screen goes up even though the scren will cover msot of it up??


----------



## eugovector




> Quote:
> Originally Posted by *daxhughes* /forum/post/0
> 
> 
> i have read all the thread but i still am confused on how I am going to treat my front wall that has a non-perforated screen that takes up most of that front wall.
> 
> 
> Should I go ahead and put OC 703 on the whole wall ebfore my screen goes up even though the scren will cover msot of it up??



No, the screen will reflect high frequencies and make the absorption ineffective and narrowband.


----------



## Terry Montlick




> Quote:
> Originally Posted by *nirvana_av* /forum/post/0
> 
> 
> Terry,
> 
> 
> Can you offer any pointers on building "bent-sheet" diffusers such as what radius of curvature is needed to be effective and what the orientation of the arc should be?



You have a lot of flexibility here.










A larger arc will diffuse down to lower frequencies. To a first approximation, a radius of curvature r will be effective at diffusing frequencies whose wavelengths are less than 2 pi r. This is not a sharp boundary -- you approach the maximum diffusion at maybe 3 or 4 times this frequency. To get the frequency for a particular wavelength in feet, just divide it into 1130 feet per second, the speed of sound. How much of a circular arc you use will depend on how much depth you are willing to allow. Varying the spacing and radius of curvature for multiple diffusers is a good idea.


One nice thing about polycylindrical diffusers is that, unlike the now-common discrete varying depth type of diffuser, they have no high frequency limit on the sounds they will effectively diffuse. As for orientation, it depends on the specific purpose of the diffusion. If it is to maintain a broad sound stage, then vertical orientation is often preferable. On the other hand, horizontal orientation will improve the uniformity of reverberation decay if you have a very uneven balance of horizontal and vertical absorption -- "dead" walls and "live" ceiling and floor, for example.


- Terry


----------



## Ethan Winer

Terry,


> polycylindrical diffusers ... are as good as the modern "well-type" diffuser in nearly all situations.


----------



## eugovector

Anyone know of any good sites dealing a DIY 2D Quad Diffuser? I found this page, with a link to the infamous BBC paper that looks helpful: http://www.mhsoft.nl/DiffusorCalculator.html 


Some people have used wood, but that seems aweful heavy. ANyone have ideas for a hard foam that would reflect well, hold it's shappe, weigh little, cost less, and come in nice, long, square lengths?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry,
> 
> 
> > polycylindrical diffusers ... are as good as the modern "well-type" diffuser in nearly all situations.


----------



## nirvana_av




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> You have a lot of flexibility here.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> A larger arc will diffuse down to lower frequencies. To a first approximation, a radius of curvature r will be effective at diffusing frequencies whose wavelengths are less than 2 pi r. This is not a sharp boundary -- you approach the maximum diffusion at maybe 3 or 4 times this frequency. To get the frequency for a particular wavelength in feet, just divide it into 1130 feet per second, the speed of sound. How much of a circular arc you use will depend on how much depth you are willing to allow. Varying the spacing and radius of curvature for multiple diffusers is a good idea.
> 
> 
> One nice thing about polycylindrical diffusers is that, unlike the now-common discrete varying depth type of diffuser, they have no high frequency limit on the sounds they will effectively diffuse. As for orientation, it depends on the specific purpose of the diffusion. If it is to maintain a broad sound stage, then vertical orientation is often preferable. On the other hand, horizontal orientation will improve the uniformity of reverberation decay if you have a very uneven balance of horizontal and vertical absorption -- "dead" walls and "live" ceiling and floor, for example.
> 
> 
> - Terry



Thanks for the tips. Now to find some time to build a few. One point of clarification on horizontal and vertical orientation. Is this diffuser oriented vertically or horizontally?

http://www.rpginc.com/products/monoradial/index.htm


----------



## Terry Montlick




> Quote:
> Originally Posted by *nirvana_av* /forum/post/0
> 
> 
> Thanks for the tips. Now to find some time to build a few. One point of clarification on horizontal and vertical orientation. Is this diffuser oriented vertically or horizontally?
> 
> http://www.rpginc.com/products/monoradial/index.htm



Vertically, at least according to my convention.


- Terry


----------



## Ethan Winer

Terry,


> http://www.rpginc.com/products/monoradial/index.htm 
http://www.rpginc.com/products/opticurve/index.htm


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> > Sorry, but this distinction is incorrect.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> If you would like to declare yourself "the winner" on this basis, go right ahead.



Woo hoo! I won!










> My interest is in promoting the understanding and practice of acoustics. 
If an "Acoustics Specialist" doesn't know what a diffuser is, this ain't my problem.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Woo hoo! I won!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> > My interest is in promoting the understanding and practice of acoustics.
> If an "Acoustics Specialist" doesn't know what a diffuser is, this ain't my problem.


----------



## eugovector

Ethan and Terry,


Out of respect for the valuable expertise that both of you possess (and that I have availed myself of), and to keep a positive vibe in this thread, could you edit your past couple post to keep things friendly, and take any other discourse to private messaging.


I'm not blowing smoke up your rears when I say this. I'm devouring everything on acoustics that I can, and this thread has some of the best info that I've found on a subject that few people want to tackle (most would rather just buy more expensive speakers for their crappy rooms). I love disagreement, but bickering could turn people off.


Finally, I for one, hope that both of you continue to contribute your honest opinions to this thread.


Thanks,


Marshall


----------



## pepar

If everyone follows one simple rule - no disrespectful posts - much space- and bandwidth-wasting banter could be avoided. Differing opinions are to be expected, but questioning someone's professionalism is out of line.


----------



## Terry Montlick

If Ethan removes his first "That's wrong on so many levels I'm not even sure where to start" message and subsequent ones, I will be happy to delete mine and forget the whole matter.


- Terry


----------



## eugovector

Anyone have any thoughts on this:

http://remixmag.com/mag/remix_diy_acoustics/index.html 


Bass Trap:


Buy a large rubber 30- or 40-gallon trash can at least 3 feet tall and without any holes in its bottom, sides or lid; then, line its circumference with bats of high-density mineral insulation (same as used for the absorbers), and loosely zigzag one or two more bats inside, being careful to leave large air pockets. Caulk around the rim of the trash can, as well as the lip of the lid, with nonhardening acoustical caulking or weather sealant, and put the lid on the can. Duct-tape the lid so that it won't accidentally come undone when you move or bump into it, and feel free to drape a decorative fabric over it. Because bass frequencies collect most in corners, bass traps are often placed in the two front corners of the room. And because bass is omnidirectional, placing them asymmetrically if space is tight won't diminish their performance one bit.


----------



## ChrisWiggles




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Anyone have any thoughts on this:
> 
> http://remixmag.com/mag/remix_diy_acoustics/index.html
> 
> 
> Bass Trap:
> 
> 
> Buy a large rubber 30- or 40-gallon trash can at least 3 feet tall and without any holes in its bottom, sides or lid; then, line its circumference with bats of high-density mineral insulation (same as used for the absorbers), and loosely zigzag one or two more bats inside, being careful to leave large air pockets. Caulk around the rim of the trash can, as well as the lip of the lid, with nonhardening acoustical caulking or weather sealant, and put the lid on the can. Duct-tape the lid so that it won't accidentally come undone when you move or bump into it, and feel free to drape a decorative fabric over it. Because bass frequencies collect most in corners, bass traps are often placed in the two front corners of the room. And because bass is omnidirectional, placing them asymmetrically if space is tight won't diminish their performance one bit.



Sounds like a silly idea. Not only do the air pockets serve no purpose, neither does caulking the lid.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *ChrisWiggles* /forum/post/0
> 
> 
> Sounds like a silly idea. Not only do the air pockets serve no purpose, neither does caulking the lid.



To say nothing of the high WAF of adding several trash cans to the family room.


----------



## eugovector




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> To say nothing of the high WAF of adding several trash cans to the family room.



Well they said you could drape a cloth covering over them ("could" implies they haven't, and just have garbage cans full of fiberglass in their home theaters)


But would it work? Not seriously considering it, just curious what people's thoughts are.


----------



## Kal Rubinson

I have no idea how effective it is but, seems to me, that should be the responsibility of the guy who designed it. Besides, are there any acoustic standards for plastic trash cans?


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> To say nothing of the high WAF of adding several trash cans to the family room.



Shabby chic?


----------



## Bobby D.

So, this is my first post on the forums and I will confess to being mostly ignorant to many of the theories discussed in this thread. I have a couple of questions about wall treatments that I have not seen answers to. I did search, with no luck, so please excuse me if I am asking something that has already been covered.


I am about 75% of the way finished with my home theatre. All of the walls in my room are insulated but I would like to block the sound a little more on the wall that is behind my tv and front channels. It seems like everyone agrees that this will benefit sound quality and that wall is common with my 2 year old's room. It sounds like insul-shield is the best stuff for the job, but I didn't have any luck at the typical home improvement stores. Lowes sells Johns Manville products but all I got was blank stares when I inquired about insul shield. Who is a common retailer for this stuff? What are some alternatives that are more readily available. Looks are not important to me as I will be hanging fabric in front of the wall anyway. What about covering the wall with acoustical ceiling tiles?


Sorry for the long post, thanks in advance for help with my noobie questions.


bd


----------



## eugovector




> Quote:
> Originally Posted by *Bobby D.* /forum/post/0
> 
> 
> So, this is my first post on the forums and I will confess to being mostly ignorant to many of the theories discussed in this thread. I have a couple of questions about wall treatments that I have not seen answers to. I did search, with no luck, so please excuse me if I am asking something that has already been covered.
> 
> 
> I am about 75% of the way finished with my home theatre. All of the walls in my room are insulated but I would like to block the sound a little more on the wall that is behind my tv and front channels. It seems like everyone agrees that this will benefit sound quality and that wall is common with my 2 year old's room. It sounds like insul-shield is the best stuff for the job, but I didn't have any luck at the typical home improvement stores. Lowes sells Johns Manville products but all I got was blank stares when I inquired about insul shield. Who is a common retailer for this stuff? What are some alternatives that are more readily available. Looks are not important to me as I will be hanging fabric in front of the wall anyway. What about covering the wall with acoustical ceiling tiles?
> 
> 
> Sorry for the long post, thanks in advance for help with my noobie questions.
> 
> 
> bd



It's a lot I know, but please read this thread all the way through. There are several links for OC 703 and the like. SPI is a popular choice, but I didn't have one in my area so EJ Davis shipped from CT to NY for me.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Shabby chic?



Shabby and trashy are quite different.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/0
> 
> 
> Shabby and trashy are quite different.



But many times they do hang out together.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> But many times they do hang out together.



Yeah. See it all the time in system pix on AVS.


----------



## DKaps




> Quote:
> Originally Posted by *Bobby D.* /forum/post/0
> 
> 
> So, this is my first post on the forums and I will confess to being mostly ignorant to many of the theories discussed in this thread. I have a couple of questions about wall treatments that I have not seen answers to. I did search, with no luck, so please excuse me if I am asking something that has already been covered.
> 
> 
> I am about 75% of the way finished with my home theatre. All of the walls in my room are insulated but I would like to block the sound a little more on the wall that is behind my tv and front channels. It seems like everyone agrees that this will benefit sound quality and that wall is common with my 2 year old's room. It sounds like insul-shield is the best stuff for the job, but I didn't have any luck at the typical home improvement stores. Lowes sells Johns Manville products but all I got was blank stares when I inquired about insul shield. Who is a common retailer for this stuff? What are some alternatives that are more readily available. Looks are not important to me as I will be hanging fabric in front of the wall anyway. What about covering the wall with acoustical ceiling tiles?
> 
> 
> Sorry for the long post, thanks in advance for help with my noobie questions.
> 
> 
> bd



Welcome, Bobby. Insul-shield will do very little to nothing to keep sound from going through (and around) that wall. Insulshield and similar products are used to improve the sound in the room, not trying to keep it in. Two different goals there. I'd add a layer of green glue and another layer of drywall on that wall. Also, don't ONLY focus on that one wall.


One last thing, find a professional HVAC supplier in your area for Insulshield and similar products.


Dan


----------



## Glenn Baumann




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Ethan and Terry,
> 
> 
> Out of respect for the valuable expertise that both of you possess (and that I have availed myself of), and to keep a positive vibe in this thread, could you edit your past couple post to keep things friendly, and take any other discourse to private messaging.
> 
> 
> I'm not blowing smoke up your rears when I say this. I'm devouring everything on acoustics that I can, and this thread has some of the best info that I've found on a subject that few people want to tackle (most would rather just buy more expensive speakers for their crappy rooms). I love disagreement, but bickering could turn people off.
> 
> 
> Finally, I for one, hope that both of you continue to contribute your honest opinions to this thread.
> 
> 
> Thanks,
> 
> 
> Marshall




I heartily concur... Ethan and Terry, you guys are very valuable to this forum and I enjoy and respect both of your opinions!



...Glenn


----------



## DMF




> Quote:
> Originally Posted by *davestern* /forum/post/0
> 
> 
> Dennis, you sound pretty firm on not using styrofoam. Is there a valid reason, if it is fire rated.



Fire rated styrofoam? Is there such a thing?


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> If everyone follows one simple rule - no disrespectful posts - much space- and bandwidth-wasting banter could be avoided. Differing opinions are to be expected, but questioning someone's professionalism is out of line.



I agree, and I apologize for coming off as combative. I will point out that I was not the first to question the other person's professionalism and competence. That's what set me off. There's some history to this and I'm frankly tired of being on the receiving end of it. But that's no excuse for me to be insulting back.


I also agree that the difference between curved surfaces and real QRD diffusors is worth exploring further. I already stated the reasons I consider a QRD to be much better than curved plywood. Not just via logical explanations and understanding of how each surface type reflects, but also based on having heard both many times.


So let's discuss, okay? I also think some measurements are in order, which is why I offered to visit Terry in person and bring along some real diffusors. Does anyone else here live near me (within a few hours) and have poly type surfaces in their room? I suppose I could fabricate one easily enough at our factory, but it probably makes more sense to have a "second opinion" for listening evaluations.


Also, Glenn Kuras at GIK told me today he thinks the subject of "poly versus QRD" deserves a thread all its own. So Glenn, or anyone else, by all means do that and we can move the discussion there if y'all agree this warrants further exploration.


--Ethan


----------



## eugovector




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> So let's discuss, okay? I also think some measurements are in order, which is why I offered to visit Terry in person and bring along some real diffusors. Does anyone else here live near me (within a few hours) and have poly type surfaces in their room? I suppose I could fabricate one easily enough at our factory, but it probably makes more sense to have a "second opinion" for listening evaluations.
> 
> 
> --Ethan



I live 1 hour away, Pleasant Valley, NY, but I live in a townhouse with shared walls, and have plenty of absorption but no diffusion. However, I'd love to offer a second opinion if a test ever comes about.


----------



## Terry Montlick

This work has already been done 13 years ago.


Trevor J. Cox & Y. W. Lain, "The Performance of Realisable Quadratic Residue Diffusers (QRDs)" Applied Acoustics 41 (1994) 237-246.


Anyone who is *honestly* interested in the subject should read this paper.


- Terry


----------



## eugovector




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> This work has already been done 13 years ago.
> 
> 
> Trevor J. Cox & Y. W. Lain, "The Performance of Realisable Quadratic Residue Diffusers (QRDs)" Applied Acoustics 41 (1994) 237-246.
> 
> 
> Anyone who is *honestly* interested in the subject should read this paper.
> 
> 
> - Terry



Do you have a link to that paper? I'd love to read it.


----------



## Ethan Winer




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> I live 1 hour away, Pleasant Valley, NY, but I live in a townhouse with shared walls, and have plenty of absorption but no diffusion. However, I'd love to offer a second opinion if a test ever comes about.



Do you have a poly on one of those walls? Or are you willing to put one on a wall?


--Ethan


----------



## pmeyer




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Do you have a link to that paper? I'd love to read it.



I found a synopsis. The only links to the paper I've found are $$:


3. T J Cox and Y W Lam. The Performance of Realisable Quadratic Residue Diffusers (QRDs). Applied Acoustics. 41. 237-246. (1994).


The scattering performances of realisable quadratic residue diffusers (QRDs) have been tested. The scattering has been compared to (i) the original design theory of the QRD; (ii) optimum diffusion; and (iii) the performance of plane and curved reflectors. The QRDs do produce similar diffusion to that predicted by the original design theory. Only at low frequencies, however, is this close to optimum diffusion. For oblique incidence the QRD produced greater diffusion than the curved and plane panels. At normal incidence, however, the curved panel was as good as the QRD.


----------



## Ethan Winer

Terry,



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> This work has already been done 13 years ago.



Great. A big part of the scientific method is for others to duplicate and see if they get the same results, so another round of tests isn't necessarily redundant. This also brings up two new questions:


1) What's the punch line? Did they determine that polys are as good as QRD or not?


2) If polys were considered subjectively (or measured) to be as good as QRD diffusors in small rooms at close distances, why did Dr. D'Antonio go into business selling QRDs? His curved stuff is much more recent, no?


I'm with Eugo - ya got a link? If not, a summary is a good start.


--Ethan


----------



## eugovector




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Do you have a poly on one of those walls? Or are you willing to put one on a wall?
> 
> 
> --Ethan



I really don't know how much my humble little room would tell use (14'x15x'8'), and with the shared walls, I don't get to let my system breathe fire as much as I would like for fear of disturbing the neighbors. I've certainly considered hanging a poly if I could find the time to build one, but I'm pretty happy with the 703 panels for now.


Mostly, I'd just like to be in on the fun if anyone in the area starts doing a listening test and would be more than willing to drive a ways.


----------



## pmeyer

A quote from the paper (stolen from a post in another thread with a similar discussion on 1/24/06 titled 'diffusion')



4.1 Normal incidence case


"In Fig. 6 two examples are given of the scattering from the three surfaces at

1.5 kHz and 7.5 kHz. The plane panel gave less uniform scattering than

either of the other two panels at all frequencies. The scattered field also has

much more pronounced minima and maxima, particularly the central

maxima at high frequencies. The result is hardly new; acousticians tend to

avoid plane reflectors in difficult areas which are likely to produce strong

specular reflections and echoes.


"Overall there seems to be little difference in the relative performances of

the curved panel and the QRD. Below about 3.5 kHz the QRD did produce

more scattering to large angles, but at the expense of having large minima at

some receiver positions. Above 3.5 kHz the amount of scattering away from

the normal direction was similar for both panels. Again the QRD had many

more, well defined minima and maxima. As illustrated in Fig. 6(a), a

particular problem for the QRD at high frequencies was that the central

maximum was large and similar to the central lobe for the plane panel.

Consequently, there seems to be a risk of strong specular reflections and

echoes from this QRD. The QRD and curved panel were constructed so that

the maximum 'depth' of the curved panel (28 cm) was of similar size to the

maximum depth of the QRD wells (35 cm). So for the same overall size in all

dimensions, and for on-axis incidence, it was possible to achieve as good if

not better diffusion with the curved panel. Curved panels are generally

cheaper to construct. So, if near normal incidence can be guaranteed, as

would be the case for reflectors over the stage area in auditoria, the curved

panel is to be preferred."


----------



## Ethan Winer

Excellent Paul, thanks!


Any others?


--Ethan


----------



## mccabem

If you "toe in" the L&R front speakers, how would that effect the positioning of acoustic panels using the mirror method? It would seem that since the speaker is pointed toward the middle listening area that the reflection would be more on the wall opposite that speaker vs. right beside it.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> If you "toe in" the L&R front speakers, how would that effect the positioning of acoustic panels using the mirror method? It would seem that since the speaker is pointed toward the middle listening area that the reflection would be more on the wall opposite that speaker vs. right beside it.



YOur speakers are not lasers. Their output is dispersed over an angle and, as long as the postion of the drivers does not change when you change the aiming, the first reflection point should not change.


----------



## mccabem

Thanks for the reply.


To apply your response to the mirror method of determining reflection points, should I only consider it a point of reflection when I can see the driver (in my case it's a 60' x 90' Horn loaded tweeter - Klipsch KL 650THX)? It seems with it being angled away from the wall that this would move your reflecting point further down the wall vs. just seeing the reflection of the speaker cabinet. Is that accurate?


Thanks,

Matt


----------



## Kal Rubinson

YOu should also recall that there is no one 'point' but an area around the mirror-determined point that needs absorption.


----------



## mccabem

Thanks. The reason I'm needing more flexibility in placement is because I'm trying to locate these in a somewhat uniform distance from my columns. I'm just trying to determine just "how much" flexibility I have by knowing where the most critical point is for placement and judging placement options from there. I plan to do panels approximate 1-2'W x 4'H.


So is the critical point just where I will see the Tractix Horn?


Matt


----------



## Scott R. Foster




> Quote:
> I've certainly considered hanging a poly if I could find the time to build one



Polys are pretty easy to build... even if you want to make them somewhat fancy by using a hardwood veneer or some such. These came out pretty nice and it doesn't look like too ambitous a project for most handy folks. [scroll down for a pic of a very simple design, and a link to a thread on more stylish unit]

http://forum.studiotips.com/viewtopic.php?t=48 


PS: If you are trying to read up a bit on diffusion, his gentleman's work might also be of interest.

http://pcfarina.eng.unipr.it/Public/.../135-AES00.PDF 

http://pcfarina.eng.unipr.it/Public/.../136-AES00.PDF 

http://pcfarina.eng.unipr.it/Public/.../138-Sem00.PDF 

http://pcfarina.eng.unipr.it/Public/...0-ACTA2000.PDF 


PPS: This thread had some interesting ideas on how to make a poly as well

http://forum.studiotips.com/viewtopic.php?t=2787 


but my all time favorite was the guy who decided to build a poly faced bar at the back of the room.


----------



## eugovector

Awesome, thanks.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> This work has already been done 13 years ago.
> 
> 
> Trevor J. Cox & Y. W. Lain, "The Performance of Realisable Quadratic Residue Diffusers (QRDs)" Applied Acoustics 41 (1994) 237-246.



Correction: that's Y.W. Lam. This was an error in Adobe Acrobat's OCR software when I copied and pasted it from my PDF version of the paper. I didn't notice it because my eyes were fooled as well.










- Terry


----------



## craig john




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> Thanks. The reason I'm needing more flexibility in placement is because I'm trying to locate these in a somewhat uniform distance from my columns. I'm just trying to determine just "how much" flexibility I have by knowing where the most critical point is for placement and judging placement options from there. I plan to do panels approximate 1-2'W x 4'H.
> 
> 
> So is the critical point just where I will see the Tractix Horn?
> 
> 
> Matt



The Klipsch THX Ultra2 speakers are designed with a wide horizontal dispersion pattern, and a narrow vertical dispersion pattern. The wide horizontal dispersion means there will be a significant amount of sound energy striking the side walls. Toeing the speakers in a little bit will reduce the amount of energy somewhat, but the first reflection point will stay physically where you see the speaker in the mirror. This is true for *each* front speaker. Therefore, there will be 3 first reflection points on each side wall, one for each of your 3 front speakers. You want to cover all 3 of them. One wide absorption panel on each side wall should do it for all 3 speakers.


Craig


----------



## pepar




> Quote:
> Originally Posted by *craig john* /forum/post/0
> 
> 
> The Klipsch THX Ultra2 speakers are designed with a wide horizontal dispersion pattern, and a narrow vertical dispersion pattern. The wide horizontal dispersion means there will be a significant amount of sound energy striking the side walls. Toeing the speakers in a little bit will reduce the amount of energy somewhat, but the first reflection point will stay physically where you see the speaker in the mirror. This is true for *each* front speaker. Therefore, there will be 3 first reflection points on each side wall, one for each of your 3 front speakers. You want to cover all 3 of them. One wide absorption panel on each side wall should do it for all 3 speakers.



A bit more needs to be added to this advice; there are three first reflection points on each side wall for EACH listening position. The conclusion remains the same though - one panel should do it for all of the points.


This is not only true for the side walls, but the ceiling, the front wall and the rear wall as well.


----------



## Scott R. Foster




> Quote:
> I didn't notice it because my eyes were fooled as well.



Dammit Terry, go get those eyeballs fixed. A blind acoustician is more irony than the any of us should have to put up with.


----------



## eugovector

I know Ethan is speaking at HES , and if anyone else is going, we should have a meetup, maybe after one of the acoustics seminars? Anyone game?


----------



## mccabem

Pepar and Craig,


Thanks for your input on the reflection point issue. How much will it matter if I have a 4"D x 12" W wood column in a reflection point area? I know it's a hard surface and it will reflect sound, but since it sticks out from the flat wall, will that help any?


Matt


----------



## mccabem




> Quote:
> Originally Posted by *craig john* /forum/post/0
> 
> 
> The Klipsch THX Ultra2 speakers are designed with a wide horizontal dispersion pattern, and a narrow vertical dispersion pattern. The wide horizontal dispersion means there will be a significant amount of sound energy striking the side walls. Toeing the speakers in a little bit will reduce the amount of energy somewhat, but the first reflection point will stay physically where you see the speaker in the mirror. This is true for *each* front speaker. Therefore, there will be 3 first reflection points on each side wall, one for each of your 3 front speakers. You want to cover all 3 of them. One wide absorption panel on each side wall should do it for all 3 speakers.
> 
> 
> Craig




Craig,


Since they do have a wide horizontal disperson pattern, would it be ok not to "toe in" the front speakers (assuming I treated the side walls properly)?


Thanks,

Matt


----------



## pepar




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> Craig,
> 
> 
> Since they do have a wide horizontal disperson pattern, would it be ok not to "toe in" the front speakers (assuming I treated the side walls properly)?
> 
> 
> Thanks,
> 
> Matt



I think it's common practice to aim all monopole (direct-radiating) speakers at the geographical center of the listening positions. Dipoles, too, but "directly at" is more of a concept with them; I suppose one aims the null at the geographical center. I use a special laser pointer system and a target balloon to do my speakers. Better speakers, including all THX-approved ones, have tightly controlled vertical dispersion, so it is especially important to properly aim them.


----------



## Ethan Winer




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> I know Ethan is speaking at HES , and if anyone else is going, we should have a meetup, maybe after one of the acoustics seminars? Anyone game?



I would love to meet you, and anyone else here. I'm sure I'll be hanging around several minutes before the discussion panel starts, so please come by and say Hi. Then we can hook up after and chat. I'll be the guy holding the big fat ***** cat.










--Ethan


----------



## mccabem

Any thoughts on having my 4"D x 12"W wood column in an area which is a first reflection point?


Thanks,

Matt


----------



## pmeyer




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> Any thoughts on having my 4"D x 12"W wood column in an area which is a first reflection point?
> 
> 
> Thanks,
> 
> Matt



Not an expert, so grain of salt time.


For medium/high frequencies that you'll worry about for first reflections, 12" wide is plenty wide to give you a reflection from a speaker. If your reflection point for your center speaker/right ear is in the middle of the column on the right side, it would act just like a wall and should be treated as such.


If your reflection point for a given speaker/ear combo is right on the front edge, you'll get ~half a reflection (the rest will be reflected forward and not be an issue). If your point is at the back edge of the column, you'll get half (the rest will continue on and hit the wall).


Bottom line: the column complicates the calculation, but it doesn't really change anything.


Have you considered curved columns? Can you move them out of the reflection point or treat them? What about moving speakers?


----------



## mccabem

The center speaker might be hidden by a fabric covered frame beneath the screen. What if I moved it towards the back of the framed area and placed some 1" 703 panels to the immediate sides and extended the panels out past the face of the speaker. This would keep it from reflecting to the side walls, but would it keep the sound of the center too localized?


Thanks,

Matt


----------



## eugovector




> Quote:
> Originally Posted by *mccabem* /forum/post/0
> 
> 
> The center speaker might be hidden by a fabric covered frame beneath the screen. What if I moved it towards the back of the framed area and placed some 1" 703 panels to the immediate sides and extended the panels out past the face of the speaker. This would keep it from reflecting to the side walls, but would it keep the sound of the center too localized?
> 
> 
> Thanks,
> 
> Matt



Yeah, that would not be good. Basically you'll kill any horizontal dispersion of high frequencies and create a very narrow sweetspot.


----------



## Terry Montlick

Hi Matt,


Paul is right. Wood column faces at early reflection points are not a great idea. This is a trade-off: aethetics vs. acoustics. The best thing would be to face the columns with 1" fiberglass and cover with fabric.


- Terry


----------



## mccabem

Thanks for all your responses. I have enough info now to weigh the options out.

Great Advice!!!!

Matt


----------



## Scott R. Foster

Perhaps slip some upholstered pipe insualtion on them?

http://einsulation.com/products-fibe...glass_pipe.php


----------



## patrickd12

Due to some of the pipes we have we had to put in a couple of soffits. We did straight 45 degree soffits on the side walls to the ceiling to conceal the pipes. I was thinking to match the room up I was going to put in bass traps in the front and rear walls and create a tray ceiling in the room. From an athetics stand point this would work, but how would this help with bass? I have room to put corner traps in 3 corners but one corner has a door too close in the rear of the room so I was leaning toward not putting corner traps in and was hoping this might help enough to offset that. or am I wasting time and money on something that really won't help much.


Any input would be great.


Thanks


----------



## Scott R. Foster

Patirck:


Corner mounted bass traps are the most effective way to control low frequencies, but preserving symmetry is also important. Can you use any floor/wall or ceiling /wall corners and keep things even [left to right]?


----------



## bpape

Do the front and back in a matching soffit but with just absorbtion and cloth. Do the front 2 room corners that you can. That should be sufficient to make a difference.


If you need more, you can square off the angled soffits on the side walls again with absorbtion.


Bryan


----------



## patrickd12

So the traps at the front and back ceiling/wall junction aren't going to help as much as a bass trap in each of the front corners?


Also not sure what to think of this but I have a friend that works at an industrial filter plant. He was telling me that he can get me a ton of free felt (more high tech then that but easy way to explain it as felt). Some of this stuff is extremely dense. I was wondering if this might be worth looking into. It won't be expensive so I might give it a shot, but I was thinking 3 or 4 layer of this on the screen wall might help absorb some sound. Any thoughts?


----------



## Scott R. Foster




> Quote:
> So the traps at the front and back ceiling/wall junction aren't going to help as much as a bass trap in each of the front corners?



Depends... both cases are corner mounted panels and will work equally well as bass traps. And either may, or may not, also be useful for controlling SBIR and/or early reflections.



> Quote:
> ...he can get me a ton of free felt (more high tech then that but easy way to explain it as felt). Some of this stuff is extremely dense. I was wondering if this might be worth looking into.



No harm in looking into it I suppose... but you need to find out what the stuff is to make a determination. If its a medium density thermal insulation product, it probably has reasonably good acoustic absorption properties. Find out exactly what it is and look it up. Though I wouldn't settle for anything that didn't have good lab numbers... and good handling properties... as excellent materials in either semi-rigid fiberglass or rockwool are available in mosts markets for modest costs.


----------



## myfipie




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> I would love to meet you, and anyone else here. I'm sure I'll be hanging around several minutes before the discussion panel starts, so please come by and say Hi. Then we can hook up after and chat. I'll be the guy holding the big fat ***** cat.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Wish I could go, but will be pretty much stepping off a plane back from the UK. Would be way to much "out of town time" for me.

Hope it all works out well for you. BREAK A LEG.










Glenn


----------



## Ethan Winer




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Wish I could go, but will be pretty much stepping off a plane back from the UK. Would be way to much "out of town time" for me.
> 
> Hope it all works out well for you. BREAK A LEG.



I'll try hard _not_ to break a leg.










But I will mention your name when I speak on the panel.










--Ethan


----------



## myfipie




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> I'll try hard _not_ to break a leg.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> But I will mention your name when I speak on the panel.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Would it be to much to ask for you to pass out some of our brochures also?


----------



## wgilpin

Back in February I posted about building my first prototype panel absorber.


Well, last night I finally finished the last of five planned panels of this design, so I thought I'd share with y'all the fruits of the knowledge in this thread. So far everything is turning out pretty well. Thanks again for everyone who has posted.


The original prototype is in the center of the second shot. Note also that the panels hanging behind the sofa are shorter to leave room for a yet-to-be-built second row riser.


I will be making at least one more of similar design. It will go behind the door seen in the first shot, but it will need to be thinner and mount flush to the wall instead of spaced away like the others.


I'm also planning to do something about the corners, and I have a couple questions about that. (See next post.)


----------



## wgilpin

Now that I'm done with my side-wall panel absorbers, I need to turn to my corner bass trapping.


Currently I have eight 2' x 4' x 4" 8lb rockwool batts straddling the room's vertical corners. For aesthetic reasons, I'd like my corner absorbers to extend 14.25" from the corners instead of the 17" you get with a full 24" panel.


(1) Would reducing the width of the panel this much reduce the effectiveness of the absorber more than the simple reduction in the volume of the material?


and on a very related note:


(2) Would building "chunk" style absorbers using all my available material recover the absorption lost due to the width reduction?


Cheers,


----------



## pmeyer

Those are great looking absorbers. Are they just a wood frame/cloth over fiberglass? or are they tuned panel absorbers?


----------



## wgilpin




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> Those are great looking absorbers. Are they just a wood frame/cloth over fiberglass? or are they tuned panel absorbers?



Thanks.

They are frames & fabric around 8lb 2" rockwool.

I tried to tune them, but I couldn't figure out where to put the knobs.










Cheers,


----------



## Terry Montlick




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> I tried to tune them, but I couldn't figure out where to put the knobs.



I have had that problem, too!

















- Terry


----------



## myfipie




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> (1) Would reducing the width of the panel this much reduce the effectiveness of the absorber more than the simple reduction in the volume of the material?
> 
> 
> and on a very related note:
> 
> 
> (2) Would building "chunk" style absorbers using all my available material recover the absorption lost due to the width reduction?
> 
> 
> Cheers,



Just so I understand correctly. You are going to build the panels that straggle the corners shorter? or are you going to build super chunks that are shorter? Sorry kind of early here.









It is all about coverage, so the shorter you make them the less area it has to pick up sound and it will reduce the air gap in the back. So all and all it will pick up less bass over all. How much, is really hard to tell, but if it was me I would stick with the face to be 24" across the corner. May it be super chunks or panels.


Hope that helps.


Glenn


----------



## jchretien4




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Now "A".
> 
> 
> In multi-channel, the entire wall behind the front speakers is treated. You want none of the back reflections to overlay the surround field or the bring the reverberent field forward (your reverberent field and surround field is created by the multi-channel processor or mix, not so much the room as is mandatory for 2-channel). Depending on speaker placement, this treatment is brought forward along the side walls. Wall treatments are floor to slightly above ear level (where exactly is also a function of front speaker heights). While one could argue the sound at their feet is of no concern, often that square footage of treatment is required to bring the room's RT60 down to the lower levels required for multi-channel playback.
> 
> 
> If you have soffits, the bottom of the soffits is also treated...several reasons, right tricorners among them.



***

I am finishing a rather narrow home theater (11' by 20') in an unfinished part of the basement by building a 'room within a room' with 2"x4" studs, thermal insulation in the walls, and 1/2 " drywall around the walls. I plan to use two 5/8" drywall layers for the ceiling, using green glue to dampen the sound through the ceiling (plus 8" of thermal insulation above). Got a 12" soffit perpendicular to the main axis of the room about 14 ' back from the front (narrow end) wall. Rug covering concrete floor. 6 reclining seats. Set-up will include a 45" HDTV centered on the front wall. Using Klipsch spkrs for 7.1 sound (Synergy F-3 series). A front projection screen will descend for movies, covering much of the front wall.


First questions concern spkr placement for the mains and the subwoofer:


1) Should mains be placed as close to the screen as possible to minimize corner effects in this set-up (i.e., maybe 6-8 feet apart?). With the screen down, spkrs will be awfully close to the corners ... will this cause a problem?


2) Should the subwoofer be placed in the center to minimize smearing?


3) With respect to acoustic treatments in such a narrow room (and with insulation in the walls), should I use 1" batting or insul-shield around the sidewalls, up to ear height, and no treatment above that? Or something else?

More (or higher) treatment because the room is narrow?


4) Front side of soffet (i.e., side facing the speakers) should be treated, I bet...?


5) Back wall treated same as sides in this case?


-Thanks for sharing your expertise -


jchretien4


----------



## eugovector

_1) Should mains be placed as close to the screen as possible to minimize corner effects in this set-up (i.e., maybe 6-8 feet apart?). With the screen down, spkrs will be awfully close to the corners ... will this cause a problem?_

*Yes, and you'll need to adjust your seating distance. Take the distance between your speakers and multiply it by 1.25 and 0.87. That's the distance from the midpoint between your speakers that your seating distance should be.


Move your fronts forward from the front wall and screen to minimize rear boundry effects and any potential acoustic reflection off the side of the screen. Is the screen perforated, or will you have you center channel below it?*
_

2) Should the subwoofer be placed in the center to minimize smearing?_
*

You'll have to listen and measure to find the best place for the subwoofer. Read up on Room EQ Wizard for free software that will help tremendously.*

_3) With respect to acoustic treatments in such a narrow room (and with insulation in the walls), should I use 1" batting or insul-shield around the sidewalls, up to ear height, and no treatment above that? Or something else?

More (or higher) treatment because the room is narrow?_

*Consider building a false front wall w 2" of absorption. This will give you better acoustics, and will get the demensions of the room a little further away from being multiples of each other. How tall are your ceilings?*

*As far as te rest, it's hard to say w/o listening to it, but you'll want to treat the first reflections for sure, at ear height. I'd start by putting in your system and seeing what it sounds like. There's no magic acoustic bullet.*
_

4) Front side of soffet (i.e., side facing the speakers) should be treated, I bet...?_

*Better yet, put in a soffit on the opposite side to keep the room symmetry.

Treat both, might even make a good place for your rear speakers if I'm doing my seating distance math correctly. What's in the soffit?*

_5) Back wall treated same as sides in this case?_

*Once again, have to listen, but it sound like you'll have a significant amount of space between you and the back wall if you do your seating distance correctly (2x screen diagonal at most. Assuming a seating distance of about 14 feet, you'll probably have 4-5 feet behind you, and you might benefit from some dispersion back there. Once again, you'll just have to give it a listen.*


----------



## jchretien4

Center channel will be below display and screen, mounted forward about 6". Screen will not be perforated. Soffit is drywall enclosing a steel girder.


So, above ear height on the sides, I should leave alone, at least to start?


Thanks for your help -


jchretien4


----------



## pmeyer

Anybody know how much of a difference 1/2" vs. 3/4" OSB will make as a second floor layer with Green Glue? I'm looking at sound isolation from the room below in a new home theater (pictures of current status here) . I'm trying to get a feel if it is worth the extra weight/expense to go for 3/4" OSB. I don't see much on the Green Glue site other than "3/4 OSB or 11/16 OSB are best, 1/2" is good". I'm trying to see if there is any more data than that. If 3/4" makes a 20%+ difference in perceived noise levels in the room below, I'm all over it. If it's a barely noticable difference, I'll go lighter.


By the way, I know this is very difficult to answer, hard to quantify, and it will vary from room to room and depend on my weakest link. For this discussion, assume the floor is my weakest link and the only path for sound getting to the room below. I'm just looking for informed gut feels.


My theater is going in an existing room in a room. The current floor is 3/4" OSB on 2x8 floor joists 16" OC with a 3" gap over the 2x6 ceiling joists in the room below. Blown in insulation on the ceiling below, R-30 pink between the floor joists.


The walls are 1/2" drywall on 2x4 studs with minimum 3" spacing to another 2x4 wall. Most of the walls and the ceiling actually face attic or roof. I'm already planning on GG/double drywall (another layer of 1/2") on the walls (5 cases of green glue up there right now).


I've just thrown GG/OSB for the floor into the plan (my wife's idea, I've been trying to avoid overdoing it). It'll cost me 12 sheets of OSB and another two cases of GG, but it'll be easy to do now that the floor is torn up.


However, I have to decided between 3/4", 11/16", or 1/2" OSB (or something else, if there are better/cheaper/lighter options) I haven't explored price yet, but the lighter the better as my wife and I have to lug it upstairs. Also, the hallway outside the room has 3/4" wood floors on top of the same subfloor. If I put 3/4" OSB, my pad/carpet will start flush with the outside floor. I'm worried about dealing with the step up on entering the room. I don't want people tripping.


Any thoughts?


----------



## patrickd12

Has anyone tried this product?

http://www.fibratec.com/ 


The blanket sounds like it could work, just waiting to see what the sound attributes are for it before I order any.


----------



## triage1998

.


----------



## wgilpin




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> Just so I understand correctly. You are going to build the panels that straggle the corners shorter? or are you going to build super chunks that are shorter?



Currently I have my 4" batts straddling the corners. The room sounds OK. I could use some more absorption from 30hz to about 80hz...but then who couldn't? (See the waterfall charts in my gallery)


What I want to do is make them shorter - from the 17" of wall space they currently occupy, down to 14.25". This will reduce the front-side length from 24" down to just over 20". I know that this will reduce the effectiveness of the panel...So, I'm wondering if switching to a "super chunk" design will adequately compensate.


Therefore, what I'd like to know is how the performance of a 20" wide "super chunk" compares to that of a 24" wide panel?


----------



## eugovector




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> Currently I have my 4" batts straddling the corners. The room sounds OK. I could use some more absorption from 30hz to about 80hz...but then who couldn't? (See the waterfall charts in my gallery)
> 
> 
> What I want to do is make them shorter - from the 17" of wall space they currently occupy, down to 14.25". This will reduce the front-side length from 24" down to just over 20". I know that this will reduce the effectiveness of the panel...So, I'm wondering if switching to a "super chunk" design will adequately compensate.
> 
> 
> Therefore, what I'd like to know is how the performance of a 20" wide "super chunk" compares to that of a 24" wide panel?



Look into a roomeqwizard/BFD combo. Google "Room EQ Wizard". If you pull down those two huge peaks, you'll notice a world of difference, and it'll only cost you about $150, which is much less than most eq solutions.


If you like it, throw the guy a couple bucks so he'll keep developing the program.


----------



## padd54

The more I read, the more confused I become.

Can I use 2" rockwool to deaden the entire front wall?

I am going to use 4" rockwool for bass traps in all four corners.

Can I treat the lower half of the side walls with 2" rock wool like the frontwall?

Does the rear wall get treated like the front wall or just some panels placed to help absorb and diffuse?

I will be placing quilt stuff on the outside of the rockwool before covering with GOM.

The floor will have pad and carpet over cement. The cieling will be treated with a few panels if I have the materials left over,

My room is 17X12.5X8.3,

I have a Sony 60XBR2, Rocket 760(l&r), Bigfoot, 300's (ss) and MFW-15 sub.

My seating will be about 7'&11" from front of TV(3"from wall).

Any comments or suggestions on my plans and questions are greatly appreciated.

Humbly.


----------



## eugovector




> Quote:
> Originally Posted by *padd54* /forum/post/0
> 
> 
> The more I read, the more confused I become.
> 
> Can I use 2" rockwool to deaden the entire front wall?
> 
> I am going to use 4" rockwool for bass traps in all four corners.
> 
> Can I treat the lower half of the side walls with 2" rock wool like the frontwall?
> 
> Does the rear wall get treated like the front wall or just some panels placed to help absorb and diffuse?
> 
> I will be placing quilt stuff on the outside of the rockwool before covering with GOM.
> 
> The floor will have pad and carpet over cement. The cieling will be treated with a few panels if I have the materials left over,
> 
> My room is 17X12.5X8.3,
> 
> I have a Sony 60XBR2, Rocket 760(l&r), Bigfoot, 300's (ss) and MFW-15 sub.
> 
> My seating will be about 7'&11" from front of TV(3"from wall).
> 
> Any comments or suggestions on my plans and questions are greatly appreciated.
> 
> Humbly.



The 2" on the front wall, and 4" bass traps should be a safe bet (are you going wih superchunk or panel style?). So would treating the first reflection points from the floor to a foot or two above ear level. Beyond that, you'll want to put you system in and give it a listen. I'd say a panel on the ceiling is a safe bet also.


Beyond that, you're going to have to see how the room sounds. If it's starting to feel dead, stop. If it sounds small, try some diffusion in the back. If it's still really live, go with absorption.


----------



## padd54

eugovector;


I was going to cut the 4" into 2' triangles and stack in the corners.

So do you think treating the entire length of the side walls up to 4' would be too much?

This all completely new to me, but I have a clean slate with my garage conversion and I want to do it the best that I can.

Thanks again.


----------



## eugovector




> Quote:
> Originally Posted by *padd54* /forum/post/0
> 
> 
> eugovector;
> 
> 
> I was going to cut the 4" into 2' triangles and stack in the corners.
> 
> So do you think treating the entire length of the side walls up to 4' would be too much?
> 
> This all completely new to me, but I have a clean slate with my garage conversion and I want to do it the best that I can.
> 
> Thanks again.



Without hearing it it's hard to say. There are no hard and fast rules. Put in a sytem, fire it up, and then add or remove absorption, and listen some more. This isn't baking, it's a fine saute.


----------



## Wesleyjr

Dennis or whomever,

Hey guys I usually build home theaters and am currently doing a commercial acoustic job. I have mostly done fabric over 1x lumber and have started using fabric mate recently. Usually I do the lighting and audio also and am dealing with any cutting that is done myself. A large local company is doing the audio and a large electical outfit is installing about 150' of track light over my fabric. Any ideas besides glueing the fabric to lumber blocking so they don't destroy my fabric when they install the track? Thanks


----------



## padd54

eugovector,


Thanks again for your response. If you are in the neighborhood in the next few weeks, stop buy and you could help me place my treatments







. This invitation is open to everyone here at AVS, I could really use the guidance and support.

But, irregardless(really a word?), I will continue on and hope for the best. I know it has got to turn out better than my chainsaw modification to the spare bedroom. That is where everything is right now.


----------



## myfipie




> Quote:
> Originally Posted by *padd54* /forum/post/0
> 
> 
> eugovector,
> 
> 
> Thanks again for your response. If you are in the neighborhood in the next few weeks, stop buy and you could help me place my treatments
> 
> 
> 
> 
> 
> 
> 
> . This invitation is open to everyone here at AVS, I could really use the guidance and support.
> 
> But, irregardless(really a word?), I will continue on and hope for the best. I know it has got to turn out better than my chainsaw modification to the spare bedroom. That is where everything is right now.



I think starting out I would go with the bass traps in the corners, 4" panels on the back wall with 2" panels in the first reflections on the side walls. Putting panels on the front wall will help but I would not deaden it right away.

Hey I would come over but you are WAY FAR!!!!!!!!!!!!











Glenn


----------



## padd54

Thanks to all for your suggestions. I will be incorporating much of them in the comming days. I will let you all know how it turns out.

Thanks again.


----------



## Avatar8481

I just got quoted a price for 1.5" insul-shield of $31.25 for 144 sqft. It comes in 2'x4' panels in a bag of 18 pieces for that price.


Now the question is just how much can I fit in my car.


----------



## pepar




> Quote:
> Originally Posted by *padd54* /forum/post/0
> 
> 
> eugovector,
> 
> 
> Thanks again for your response. If you are in the neighborhood in the next few weeks, stop buy and you could help me place my treatments
> 
> 
> 
> 
> 
> 
> 
> . This invitation is open to everyone here at AVS, I could really use the guidance and support.



Any good Pinots nearby?


----------



## eugovector




> Quote:
> Originally Posted by *Avatar8481* /forum/post/0
> 
> 
> I just got quoted a price for 1.5" insul-shield of $31.25 for 144 sqft. It comes in 2'x4' panels in a bag of 18 pieces for that price.
> 
> 
> Now the question is just how much can I fit in my car.



That's a great price. What company did you get this from?


----------



## eugovector




> Quote:
> Originally Posted by *padd54* /forum/post/0
> 
> 
> eugovector,
> 
> 
> Thanks again for your response. If you are in the neighborhood in the next few weeks, stop buy and you could help me place my treatments
> 
> 
> 
> 
> 
> 
> 
> . This invitation is open to everyone here at AVS, I could really use the guidance and support.
> 
> But, irregardless(really a word?), I will continue on and hope for the best. I know it has got to turn out better than my chainsaw modification to the spare bedroom. That is where everything is right now.



You're welcome. I'll be in Portland in late June, don't wait for me though.


----------



## kbgl

I want to cover some wood frames with GOM cloth. Is it hard, or easy to do?


Does the fabric stretch? What about wrinkles? Should I do a small roundover on the edges with a router? Other suggestions?


----------



## pepar




> Quote:
> Originally Posted by *kbgl* /forum/post/0
> 
> 
> I want to cover some wood frames with GOM cloth. Is it hard, or easy to do?
> 
> 
> Does the fabric stretch? What about wrinkles? Should I do a small roundover on the edges with a router? Other suggestions?



Visit _here_ and then ask any follow-up/remaining questions you might have.


----------



## wgilpin




> Quote:
> Originally Posted by *kbgl* /forum/post/0
> 
> 
> I want to cover some wood frames with GOM cloth. Is it hard, or easy to do?
> 
> 
> Does the fabric stretch? What about wrinkles? Should I do a small roundover on the edges with a router? Other suggestions?



It can be easy, or it can be hard. It's pretty easy if you're OK with covering the frame, like Pepar's site shows. If you want the wood of the frame to be exposed, it's a little more involved. ( See pics here )


In either case, if you begin stapling at the center of each side, then gradually work your way out to the corners you'll have a nice flat wrinkle-free surface. It's not the fastest method, since you switch sides 10 or 20 times, but it'll generate the best results. A pneumatic stapler is your friend.


GoM is some pretty tough stuff. There's no real need for rounding the edges over unless it gives you a look that you're after.


The fabric does not stretch much at all. If you pull really hard you can stretch it a bit, but the moderate amount of tugging you'll use to get a flat wrinkle-free surface will not stretch the fabric.


Cheers,


----------



## pepar




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> 
> It can be easy, or it can be hard. It's pretty easy if you're OK with covering the frame, like Pepar's site shows. If you want the wood of the frame to be exposed, it's a little more involved. ( See pics here )
> 
> 
> In either case, if you begin stapling at the center of each side, then gradually work your way out to the corners you'll have a nice flat wrinkle-free surface. It's not the fastest method, since you switch sides 10 or 20 times, but it'll generate the best results. A pneumatic stapler is your friend.
> 
> 
> GoM is some pretty tough stuff. There's no real need for rounding the edges over unless it gives you a look that you're after.
> 
> 
> The fabric does not stretch much at all. If you pull really hard you can stretch it a bit, but the moderate amount of tugging you'll use to get a flat wrinkle-free surface will not stretch the fabric.



Something to keep in mind is that when you are done, you want the material slightly stretched in all directions. To do this w/o creases/wrinkles, the GOM should be stretched outward from the first staple as additional staples are made. Go to the opposite side, stretch it away from the just-stapled side AND stretch it also from the first middle staple as more staples are placed. That way when you start stapling the opposite sides, it will be "pre-stretched" and all you need to do is tighten it up a bit.


Hope this makes sense. I know how to do it and what I was trying to say and it still is confusing to see it in words.


----------



## bommai

What kind of room treatments do I need? Here are some pictures from my home theater setup. I have never done room treatments before. There is a wall next to might right speaker. But there is plenty of space (18 feet) to the left of the left speaker. This is an L-shaped room in the basement. My rear speakers are mounted on the beam and there is plenty of space behind the rear speakers (18-20 ft). I have a 5.1 setup. Thanks.


----------



## eugovector




> Quote:
> Originally Posted by *bommai* /forum/post/0
> 
> 
> What kind of room treatments do I need? Here are some pictures from my home theater setup. I have never done room treatments before.




Pictures aren't anywhere near as valuable as an overhead sketch w/ room demensions. If you provide those, yo'll get lots of help.l


----------



## Terry Montlick

Bommai:


Based on your plan view over on "Are Linacoustic and Duct Liner the same?" I would revisit the layout of your room. The "missing" wall directly to the left of your front speakers is a significant issue because it makes the left/right sound field highly asymmetrical. Is there any way you could use the room at the upper right end of the "L" instead, placing the screen at the far end of the L? How about building a wall to create a symmetrical room? These sorts of measures depend on your level of commitment to the acoustic quality of the space, of course.


Oh, and I would definitely get that ugly lady off the TV screen!










Regards,

Terry


----------



## padd54

OK, here a prop[osed layout of my currently under construction.











I am soliciting any and all comments/suggestions for treatments, speaker placement, etc...


BT = 4" rockwool bass traps. I have lots of 2" rockwool for treatment of room.

Thanks.


----------



## BasementBob

padd54:


By the dots between the couch and the TV, I'm assuming you drew the room to scale at one square = 6".


Nevertheless, what's the room HEIGHT/width/length.


----------



## padd54

Sorry, 8.3hX12.5wX17.2l. The dots were me counting, like I do on my fingers.

Thanks,


----------



## BasementBob

padd54:


from: http://www.rpginc.com/products/roomoptimizer/index.htm 
http://www.bobgolds.com/padd54/RoomOptimizer.GIF 



from: http://bobgolds.com/Mode/RoomModes.htm 

Computed Information:

Room Dimensions: Length=17.2 ft, Width=12.5 ft, Height=8.3 ft

Room Ratio: 1 : 1.5 : 2.07

R. Walker BBC 1996:

- 1.1w / h 
- l 
- no integer multiple within 5%: Fail (ratio3 = ratio1 * 2)

Nearest Known Ratio:

- "7) M. M. Louden: 1971: 3rd best ratio" 1 : 1.5 : 2.1

RT60 (IEC/AEC N 12-A standard): 242 ms

- ±50ms from 200Hz to 3.5kHz = 192 to 292ms

- ±100ms above 3.5kHz = 142 to 342ms

-


----------



## padd54

Could you please translate this for me??


----------



## BasementBob

padd54:


There's lots of debate as to wether either of the two algorithms I've choosen are suitable to any purpose. i.e. computer simulation is a waste of time without a lot more thought, and RT60 as a basis ( http://bobgolds.com/Mode/RoomModes.htm ), and simple frequency response modeling http://www.rpginc.com/products/roomoptimizer/index.htm ) is a waste of time.


That said

a) RoomOptimizer. Have a look at the .GIF link I provided. It shows a 'best' (yellow) location for 3-front-speakers/2-dipole-speakers/listener. It puts your speakers in places less likely to energize modes, and your head in a spot least likely to be met by trouble some modes, and reasonable angles for imaging and so on. Basically a possibly good frequency response spot.

b) A sabin is a unit of absorption per square foot. If you've got 1.0 absorption coefficients for some frequency band on the materials on your front walls and floor
http://www.bobgolds.com/AbsorptionCoefficients.htm 
http://www.bobgolds.com/Sabin%20Data_sorted.htm 

Then the ( RoomModes.htm ) line
*(sabins - front wall - carpet) / Left+Right+Rear wall: 31 %*

means that you may treat up to 31% of the surface area of your left/right/rear wall with absorption and still be ok. Start with the first reflection point locations shown in the GIF.


For a room of your volume, the ITU formula suggested an RT60 of 199 ms.

That means you can have up to 439 sabins of absorption in your room.

So if you're using things with 1.0 absorption coefficients, that means you can't exceed 439 square feet of absorptive materials (linacoustic, carpet, curtains, fuzzy couches, etc). [gross simplification] That's part of where that 31% comes from -- handilly calculated for you.


The key phrase there is "up to". Build a couple, put them in, if it sounds better, that's good.


If your speakers have bad off-axis response, then toe your speakers in a bit. Try to ensure that all reflections are reduced by 10dB by whatever means possible, relative to the direct sound.


The next thing you do is follow the 10 steps shown here, as far as you can. Ignore the equipment they use, and use whatever you have that does the same job.
http://www.sencore.com/newsletter/No...ioCalpart2.htm 


Position your subwoofers so that they minimally energize modes, and then using the "p q r mode frequency" chart above to decide where to place bass traps and what kind of bass traps for those modes that will still be energized due to the subwoofer placement.


----------



## BasementBob

padd54:


There are three traditional techniques for room treatment, that seem to be popular at AVS, that each take advantage of different things.



> Quote:
> Originally Posted by *DE Style* /forum/post/0
> 
> 
> a) dedicated home theater room with leather seating for 5 and 7.1 sound
> 
> b) reasonably soundproofed (walls/ceiling/floor, doors, HVAC)
> 
> c) front wall covered with 1" linacoustic, including behind the screen
> 
> d) side and rear walls covered from floor to half way up with 1" linacoustic. This 'half way point' must be at least 6" higher than the reflection point from the front speakers tweaters to the listener's ears
> 
> e) side and rear walls covered from ceiling to half way down with 1" Polybatting 16oz
> 
> f) bottom of soffets covered with 1" 703
> 
> g) really thick carpet on the floor
> 
> h) columns, except where the speakers were, filled with fluffy pink insulation with GoM sides
> 
> i) some sort of bass trap system (6" 703 with 4" air gap, membrane absorbers, helmholtz riser, etc)
> 
> j) 2 or more subwoofers, placed optimally





> Quote:
> Originally Posted by *studiotips style, aka Scott R. Foster's ABCs of room design* /forum/post/0
> 
> 
> 1)keep all absorption broad band to the very end - treat specific frequencies only if you can find no way around it;
> 
> 2) start in the corners (superchunks), floor to ceiling. Panels as wide and as deep as you dare - catch em all big and small;
> 
> 3) treat the front of the room for early reflections with absorption / front wall-ceiling shaping / adjusting mix-speaker position / voodoo dolls;
> 
> 4) defeat flutter [either absorbers, or diffusion] keeping in mind that if you have a flat ceiling, the floor to ceiling flutter is by far the largest area of parallel flat surfaces and therefore probably needs the most attention;
> 
> 5) Add broadband absorption to hit your desired RT60 [wall panels / clouds /
> 
> ceiling grid].
> 
> 
> Start with the corners and remember that ceiling grid is a cheap and effective tool in trying to piece a solution together for your room - keep in mind that if polys are used for wall
> 
> flutter [vs. wall mounted absorption panels] then treating whole ceiling is a great way to go - it just about takes that giant floor to ceiling thingy out of the equation entirely - you can almost forget 3d and start thinking in 2d [plan view].
> 
> 
> Jeff adds
> 
> "At least 20% to 35% coverage of walls and ceiling with good acoustical treatment fairly evenly distributed will go a long way in a small room. For mixing areas, treating the early reflection points first is key. After that, so on and so forth into bass and diffusion and the rest as appropriate."





> Quote:
> Originally Posted by *several panels, just everywhere* /forum/post/0
> 
> http://www.realtraps.com/cust_ht1.jpg
> http://www.realtraps.com/cust_ht2.jpg
> http://www.realtraps.com/cust_ht3.jpg
> http://www.realtraps.com/cust_ht4.jpg
> http://www.realtraps.com/cust_ht5.jpg




And there are other styles.


Then there's HAA, and designers (DesignCinema, Alpha Cert, etc).


----------



## padd54

BasementBob, thanks so much for taking the time to do this. Your input has been the most eyeopening of any that I have been given. I am much more prepared to tackle my room acoustics now. Still very intimidated, but better prepared. This should be fun.

Thanks again, you have been a tremendous help.


----------



## S2G-Unit

Some help needed here guys.


I drew in some places were I'm guessing the panels should go. Will there be too many in my small 11x20 room?

1st reflections points are all done.


I want to get rid of the little bit of echo above the seat near the side speakers.

So 1 panel above the 1st row? and then panels beside the side speakers?


What do you guys think?










What do you guys think of the huge bass trap I made where the was space for a bookcase before?


----------



## Ethan Winer




> Quote:
> Originally Posted by *S2G-Unit* /forum/post/0
> 
> 
> So 1 panel above the 1st row? and then panels beside the side speakers?



Absorbers on the sides walls (and ceiling) should go at the first reflection points. These are specific locations and you need to measure to find them, or use a mirror. These two articles explain the basics:

http://www.realtraps.com/art_room-setup.htm 
http://www.realtraps.com/rfz.htm 


Then feel free to follow up here with any questions. Or better, start a new thread since this one is _long past_ being manageable.










--Ethan


----------



## S2G-Unit




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Absorbers on the sides walls (and ceiling) should go at the first reflection points. These are specific locations and you need to measure to find them, or use a mirror. These two articles explain the basics:
> 
> http://www.realtraps.com/art_room-setup.htm
> http://www.realtraps.com/rfz.htm
> 
> 
> Then feel free to follow up here with any questions. Or better, start a new thread since this one is _long past_ being manageable.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan




Sorry, forgot to show in the pictures. My 1st reflection points are already done with the mirror, for the ceiling and side walls.


Any other info would be great


----------



## pepar




> Quote:
> Originally Posted by *S2G-Unit* /forum/post/0
> 
> 
> Sorry, forgot to show in the pictures. My 1st reflection points are already done with the mirror, for the ceiling and side walls.
> 
> 
> Any other info would be great



Well, how does it _sound_?


----------



## S2G-Unit




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Well, how does it _sound_?



Obviously amazing. I was just wondering at what point will I have too much absoprtion?


I don't really plan to use RTA or any fancy gadgets to test and make sure.


----------



## myfipie




> Quote:
> Originally Posted by *S2G-Unit* /forum/post/0
> 
> 
> Obviously amazing. I was just wondering at what point will I have too much absoprtion?
> 
> 
> I don't really plan to use RTA or any fancy gadgets to test and make sure.



As far as bass trapping you will never have enough, but for the high end you really want to focus on those early reflections and see how it sounds. If all is good then stop! If you feel as you want to tame a little more but not wanting the room to be to dead you can cover the bass traps with FRK which will reflect some of the high end but absorb lows.


Glenn


----------



## drin




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Absorbers on the sides walls (and ceiling) should go at the first reflection points. These are specific locations and you need to measure to find them, or use a mirror. These two articles explain the basics:
> 
> http://www.realtraps.com/art_room-setup.htm
> http://www.realtraps.com/rfz.htm



Alternatively, save yourself all that trouble and use this .


-drin


----------



## S2G-Unit




> Quote:
> Originally Posted by *myfipie* /forum/post/0
> 
> 
> If all is good then stop! Glenn




thanks


----------



## rutlian

newbie question here....


Anybody familiar with insulfoam that you can find with lowes hardware store?

can this be use as sound absorber by just covering them with a fabric?

they have a size of 2x4x8 that can be cut into diff sizes. And have anybody use

Owens corning 700 series If I use this 700 series can I just covered it with fabric?


I would like to improve the sounds quality of my hometheater

it is 14x20 room. Any suggestions is very much appreciated.


I have polk audio speakers

Onkyo reciever 6.1



Thanks


----------



## eugovector




> Quote:
> Originally Posted by *rutlian* /forum/post/0
> 
> 
> newbie question here....
> 
> 
> Anybody familiar with insulfoam that you can find with lowes hardware store?
> 
> can this be use as sound absorber by just covering them with a fabric?
> 
> they have a size of 2x4x8 that can be cut into diff sizes.
> 
> 
> I would like to improve the sounds quality of my hometheater
> 
> it is 14x20 room. Any suggestions is very much appreciated.
> 
> 
> I have polk audio speakers
> 
> Onkyo reciever 6.1
> 
> 
> 
> Thanks



Not familiar with the product, but generally speaker:


It it is a glass or mineral based board or sheet that is comprised of woven fibers, it will probably absorb pretty well.


If it is what I think it is, and it's a hard, rigid foam like the kind a beer cooler would be made out of, it will reflect sound, and won't help you a bit unless you're planning on building a diffuser out of it.


If you have a product link, post it.


Thanks,


Marshall


----------



## ChrisWiggles

If it's the solid foam insulation that I'm thinking about, not that would be a horrible absorber and would not at all be effective whatsoever.


----------



## rutlian

Marshall and Chriswiggles,


I think both of you are right about this insulation, it is just a solid foam insulation. This are

very visible in lowe's store and I always wonder if they are ok to use as sound absorber.

any other option that you guys might suggest. or a link that I can check out. I am looking for atleast 4 piece of 2x4x8 thank you guys .


Peter


----------



## ChrisWiggles

You should get fiberglass board as is suggested regularly. EJ Bartells has JM product right there in Renton, I drive out there to get what I need. They usually have everything in stock too.


----------



## rutlian




> Quote:
> Originally Posted by *ChrisWiggles* /forum/post/0
> 
> 
> You should get fiberglass board as is suggested regularly. EJ Bartells has JM product right there in Renton, I drive out there to get what I need. They usually have everything in stock too.




Thank you very much I will check them out.


----------



## rutlian




> Quote:
> Originally Posted by *ChrisWiggles* /forum/post/0
> 
> 
> You should get fiberglass board as is suggested regularly. EJ Bartells has JM product right there in Renton, I drive out there to get what I need. They usually have everything in stock too.




Hi there first thanks for giving me this information about ej bartells it is a big help

specially that they are located locally. I checked their product lines and I noticed

they have rigid and semi rigid insulation section under that section they have fiberglass board can you just cover this with tick frabic that you can get at jo-anns?



Thanks


----------



## eugovector




> Quote:
> Originally Posted by *rutlian* /forum/post/0
> 
> 
> Hi there first thanks for giving me this information about ej bartells it is a big help
> 
> specially that they are located locally. I checked their product lines and I noticed
> 
> they have rigid and semi rigid insulation section under that section they have fiberglass board can you just cover this with tick frabic that you can get at jo-anns?
> 
> 
> 
> Thanks



Tere are a number of different approaches. Some people, like me, build wooden frames, then cover the fiberglass with thin quilt stuffing to keep the fibers from getting out, and cover the frames with a thin, cotton fabric. Some people forego the frames and just use 3m spray adhesive to glue the fabric to the fiberglass. Once again, stick w/ natural fiber fabric.


Here's a thread with my construction pics:

Pics of Acoustic Frame Construction


----------



## rutlian




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> Tere are a number of different approaches. Some people, like me, build wooden frames, then cover the fiberglass with thin quilt stuffing to keep the fibers from getting out, and cover the frames with a thin, cotton fabric. Some people forego the frames and just use 3m spray adhesive to glue the fabric to the fiberglass. Once again, stick w/ natural fiber fabric.
> 
> 
> Here's a thread with my construction pics:
> 
> Pics of Acoustic Frame Construction




Thank you very much for the info. I am writing all of this info so this will be a

great help for building the panels again thanks for all the reply.


Peter


----------



## BasementBob

rutlian:

Consider fire treated fabric (either bought fire treated, or post-purchase treated)


----------



## Terry Montlick




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> rutlian:
> 
> Consider fire treated fabric (either bought fire treated, or post-purchase treated)



Absolutely! And 100% polyester, though not a natural fabric, is naturally flame retardent. You can often get certified Class A fire rating documentation if it is wall panel fabric produced by a major manufacturer.


- Terry


----------



## ChrisWiggles




> Quote:
> Originally Posted by *rutlian* /forum/post/0
> 
> 
> Hi there first thanks for giving me this information about ej bartells it is a big help
> 
> specially that they are located locally. I checked their product lines and I noticed
> 
> they have rigid and semi rigid insulation section under that section they have fiberglass board can you just cover this with tick frabic that you can get at jo-anns?
> 
> 
> 
> Thanks



Yes, that's what many people do. You'll want to get fabric that *IS* acoustically transparent though.


edit: sorry, that *IS* acoustically transparent. I was writing is *not* acoustically reflective but I lost my train of thought.


----------



## jchretien4

Small home theater is halfway there; got 2" x 4" studs up, with insulation between studs (3 - 4" of fiberglass, 16 inches o.c.); wiring and everything else done. To drywall or not to drywall, that is the question. After reading so many discussions re: the need for absorption, I wonder if I should leave off the drywall -- at least in some areas -- and cover the insulation with something acoustically transparent. In other words, I can drywall the whole room and then install absorbent panels at the early reflective points, and basstraps in the corners. But as an alternative, what about leaving sections without drywall where I would otherwise put absorbent panels or basstraps, and instead cover the studs (and the insulation) with something acoustically transparent, maybe covering it with fabric, so that the installed insulation serves as the absorbing panel (and the studs may serve as diffusers, I imagine)? In the corners I could add add to the insulation, building it out so that the corner is no longer 90 degrees, but two 45-degree angles, with about a 12-inch depth to the corner. Then cover the bass trap with transparent fabric. Maybe put something different in the corner to better trap bass frequencies, but you get the idea. Maybe use something with some rigidity for strength to cover the insulation, but not drywall.


This approach saves me the time to drywall those areas/corners and also might increase useable volume, since the walls won't be built out so much.


Am I crazy, or just lazy?


jchretien4


----------



## Terry Montlick




> Quote:
> Originally Posted by *jchretien4* /forum/post/0
> 
> 
> Small home theater is halfway there; got 2" x 4" studs up, with insulation between studs (3 - 4" of fiberglass, 16 inches o.c.); wiring and everything else done. To drywall or not to drywall, that is the question. After reading so many discussions re: the need for absorption, I wonder if I should leave off the drywall -- at least in some areas -- and cover the insulation with something acoustically transparent.
> 
> ...
> 
> Am I crazy, or just lazy?
> 
> 
> jchretien4



No comment on your motivation!







But without drywall, you will not have the opportunity to acoustically isolate your room, either from outside noise or from movie sound reaching other areas of your home. And your local building code may not allow a lack of drywall.


Regards,

Terry


----------



## Dennis Erskine

Not to take anything away from Terry's comment, you also run the risk of over absorption in the room.


----------



## Sands_at_Pier147




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Not to take anything away from Terry's comment, you also run the risk of over absorption in the room.



Which brings up a point that has been nagging me for a while. It seems the conventional wisdom is 1" linacoustic on the entire front wall, something diffusive on the real wall, nothing on the ceiling, 1" linacoustic on the lower portion of the side walls, and 1" poly batting on the upper portion of the side walls. I have always just assumed that for the side wall that meant the entire wall. The engineer in me, however, needed to calculate something, and I decided that that much absorption was waaayyyy too much. Multiple methodologies confirmed that for me.


If one were to follow the conventional wisdom, is it true that one would over absorb their room? Or am I wrong in thinking I need to treat the entire side wall on both sides? Does the conventional wisdom need to be applied with the knowledge that treating the entire room is too much, and only a portion of the side walls should be treated?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Sands_at_Pier147* /forum/post/0
> 
> 
> Which brings up a point that has been nagging me for a while. It seems the conventional wisdom is 1" linacoustic on the entire front wall, something diffusive on the real wall, nothing on the ceiling, 1" linacoustic on the lower portion of the side walls, and 1" poly batting on the upper portion of the side walls.



The "conventional wisdom" is one particular design strategy. In the rooms that I design, I use many different approaches. It depends on the specific goals of the theater owner, room configuration, constraints, etc. When acoustic measurement and modeling tools are used, the range of possibilities become greater than a one-size-fits-all approach.


Regards,

Terry


----------



## Sands_at_Pier147

That's what I thought. Thanks for clarifying that for me. I guess I can proceed with my revised plan (less absorption) and still expect satisfactory results.


----------



## myfipie




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> The "conventional wisdom" is one particular design strategy. In the rooms that I design, I use many different approaches. It depends on the specific goals of the theater owner, room configuration, constraints, etc. When acoustic measurement and modeling tools are used, the range of possibilities become greater than a one-size-fits-all approach.
> 
> 
> Regards,
> 
> Terry



There are general things in a room you can do which will yield some pretty nice results,(Bass Trapping and RFZ) but I could not agree more with you, that is why we have guys like you, Dennis and Bryan (bpape) in the world.











Glenn


----------



## Ethan Winer




> Quote:
> Originally Posted by *Sands_at_Pier147* /forum/post/0
> 
> 
> It seems the conventional wisdom is 1" linacoustic on the entire front wall, something diffusive on the real wall, nothing on the ceiling, 1" linacoustic on the lower portion of the side walls, and 1" poly batting on the upper portion of the side walls ... The engineer in me ... decided that that much absorption was waaayyyy too much.



Yes, that's not only way too much, but also the wrong type of absorption. The problem with using only "thin" absorption is it leads to an imbalanced decay time versus frequency. The room becomes too dead at mid and high frequencies, while the bass still bounces around the room yielding a muddy boomy sound.



> Quote:
> Does the conventional wisdom need to be applied with the knowledge that treating the entire room is too much, and only a portion of the side walls should be treated?



In this case the conventional wisdom is wrong. A better approach is as much bass trapping as possible, plus broadband absorption at all first reflection points including the ceiling, and more broadband absorption as needed elsewhere such as on opposing parallel surfaces. By "broadband" I mean effective down to 250 Hz or even lower, which requires using materials at least two inches thick.


--Ethan


----------



## daxhughes

Ok, I have completed my theater room and I am stupified by the thought that I cannot even tell if my room sounds acoustically good or not.


I have the following equipment:


B&W 804s

B&W HTM3s center

B&W DS8's in the back

Sub is a SVS PB12-Ultra


My receiver is a Denon 4806Ci.


I know I have decent equipment and to be honest, it sounds good to me. This is frustrating to admit but I do not know how to tell if it would sound better with acoustic treatment or not.


I am considering gettign an acoustic package from Ethan whose opinion I trust but I hate to spend the money if my ears are nto goign to eb able to tell the difference.


So why not leave it alone and enjoy? Because I cannot stand the idea that I might be able to hear a difference!


I have this eery feeling that some could come and begin pointing out to me acoustical issues that I would then see but now I am pretty clueless.


Is it a 100 percent fact that if I pur Acoustic shields at first reflective points and bass traps in the corners, that my room will sound better when it sounds pretty good already.


I attached a picture under the attach files. hopefully you see it.


----------



## DKaps

Dax,


That's a valid question. Keep in mind that we only "know" what we've been exposed to. What sounds great to you now, may not after some 1st hand education of what's possible. That said, there's no question that your equipment is capable of greatness.


You could post your general location and chances are, someone on this forum will have a suggestion for a treated room that you could demo nearby. On the other hand, the trouble with that is, you may not know if that room is actually "good" either. Hopefully, there will be one that you can visit where the design and treatment was done by a known respected designer.


Dan


----------



## pepar




> Quote:
> Originally Posted by *daxhughes* /forum/post/0
> 
> 
> Ok, I have completed my theater room and I am stupified by the thought that I cannot even tell if my room sounds acoustically good or not.
> 
> 
> I have the following equipment:
> 
> 
> B&W 804s
> 
> B&W HTM3s center
> 
> B&W DS8's in the back
> 
> Sub is a SVS PB12-Ultra
> 
> 
> My receiver is a Denon 4806Ci.
> 
> 
> I know I have decent equipment and to be honest, it sounds good to me. This is frustrating to admit but I do not know how to tell if it would sound better with acoustic treatment or not.
> 
> 
> I am considering gettign an acoustic package from Ethan whose opinion I trust but I hate to spend the money if my ears are nto goign to eb able to tell the difference.
> 
> 
> So why not leave it alone and enjoy? Because I cannot stand the idea that I might be able to hear a difference!
> 
> 
> I have this eery feeling that some could come and begin pointing out to me acoustical issues that I would then see but now I am pretty clueless.
> 
> 
> Is it a 100 percent fact that if I pur Acoustic shields at first reflective points and bass traps in the corners, that my room will sound better when it sounds pretty good already.
> 
> 
> I attached a picture under the attach files. hopefully you see it.



#1 - Any room with NO acoustical treatment will sound better with SOME acoustical treatment. And you _will_ hear the difference.


#2 - DIY is w-a-y less expensive than any commercial solution.


----------



## pepar




> Quote:
> Originally Posted by *daxhughes* /forum/post/0
> 
> 
> Ok, I have completed my theater room and I am stupified by the thought that I cannot even tell if my room sounds acoustically good or not.



Is all of the dialog intelligible/easy to understand? Do whispers sound like whispers and explosions like explosions?


----------



## brianunknown

Just beginning to build my theatre. Some of the answers I am looking for are probably in here but at 77 pages long it would take forever to read.


My room is approx 19' long by 11' wide at the front and 12' wide at the back. Ceiling height is 7' 10". Two walls are exterior walls and I have done nothing except 1/2" drywall. The other two walls have double 5/8" with GG and the ceiling is the same except it is on hat channel. All wiring and lighting will be in the soffit around the room which I will install after I complete the screen wall.


I plan to use screen paint directly on the drywall and then frame around the whole thing to mount the speakers and equipment. This means the framing will come out approx 22" and then be covered with fabric.


Now my questions:

Because I am trying to have the biggest screen possible I will only have approx 16" on either side of the screen. I also have an electric panel to deal with. As a result I can not build triangle style corner bass traps. I will only be able to fit in ones that would be rectangular (approx 15" x 12" and running floor to ceiling) I was thinking of using Roxul Safe n Sound. Will these work? Is it worth it?


If I do the traps described above they will cover both sides of my screen which leaves the only other area left on the front wall what's above and below the screen. Should this area be treated with duct liner? Will it make any difference.


Due to my limited space I may have a similar challenge on the back wall should I put small rectangular bass traps in the corner or is it a waist of time?


I am hoping to put some wall treatments up to at least deal with first reflections. I have seen some threads where people have used there soffits to deal with sound management issues as well but I would prefer the simpler approach of closing them in. How much extra sound quality can be gained by using the soffits in some way?


----------



## jv225

Hi guys. I'm starting to treat my room and had a couple questions. I just picked up some 2" rigid fiberglass and plan to double it up in the corners for bass traps and use a single layer for first reflections.

I have a drop ceiling with 2' x 2' acoustic tiles now. I was planning on cutting some of this rigid fiberglass to drop in the grids and cover them in fabric. But then I got thinking is it really necessary on the ceiling with these tiles? If so could I put a few panels on top of the tiles and get the same effect?

Thanks in advance

Jim


----------



## padd54

I would say save your ceiling for last, you may not need to treat it at all







.


----------



## Terry Montlick




> Quote:
> Originally Posted by *jv225* /forum/post/0
> 
> 
> Hi guys. I'm starting to treat my room and had a couple questions. I just picked up some 2" rigid fiberglass and plan to double it up in the corners for bass traps and use a single layer for first reflections.
> 
> I have a drop ceiling with 2' x 2' acoustic tiles now. I was planning on cutting some of this rigid fiberglass to drop in the grids and cover them in fabric. But then I got thinking is it really necessary on the ceiling with these tiles? If so could I put a few panels on top of the tiles and get the same effect?
> 
> Thanks in advance
> 
> Jim



If the room has a high level of wall diffusion, such ceiling-mounted fiberglass with an airspace or light fiberglass batts above can be effective in lowering overall reverberation and improving bass performance. It's hard to say for sure without doing the necessary acoustical measurements and modeling. I have observed this in rooms which had a ton of nooks and crannies, uneven shelves, cabinets, etc.


Regards,

Terry


----------



## jv225

Ok thanks a lot guys. I think I'll hold off on the ceiling for now and see how it goes after I build the bass traps and panels for the side wall. If I still need more I'll try insulating the whole ceiling with 12" batts since I was thinking of doing that anyway for sound isolation.


----------



## surfshoptom

There's a source in town for Linacoustic. A 100' roll is $202. Should I shop around or that a decent price?


I plan to attach 2 layers of the 1" Linacoustic to the screen wall and build covered 1" panels for the side walls.


Does Linacoustic have a backing? If so, does the backing go against the wall or on the outside? When I double it up, how do I place the backing?


Thanks.


----------



## antropos

hi


after thousand search I buy the Daad.

this one is italian product so expensive but really good acoustic tractament for room.this really good beetween tub trubs.

actualli have almost end my room dedicated a home theatre.


----------



## Fatawan

Can fabrics other than the GOM types be used to cover the acoustical treatments? I want it to look nice as well, and am looking at a fabric that is 63% polyester/37% cotton with an acrylic latex backing. It's 13 oz. per linear yard.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Fatawan* /forum/post/0
> 
> 
> Can fabrics other than the GOM types be used to cover the acoustical treatments? I want it to look nice as well, and am looking at a fabric that is 63% polyester/37% cotton with an acrylic latex backing. It's 13 oz. per linear yard.



Two problems come to mind immediately:


Polyester/cotton blends can be highly flamable, and not meet the NFPA 701 flame propagation standard required for safety by most building codes.


The acylic latex backing will likely render the fabric acoustically reflective, at least for medium and high frequencies. This will prevent sound from getting absorbed by porous acoustic treatment materials.


Regards,

Terry


----------



## Fatawan




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Two problems come to mind immediately:
> 
> 
> Polyester/cotton blends can be highly flamable, and not meet the NFPA 701 flame propagation standard required for safety by most building codes.
> 
> 
> The acylic latex backing will likely render the fabric acoustically reflective, at least for medium and high frequencies. This will prevent sound from getting absorbed by porous acoustic treatment materials.
> 
> 
> Regards,
> 
> Terry



Thanks Terry--that makes perfect sense. How about something like 100% cotton that I could fire-treat myself?


----------



## drin




> Quote:
> Originally Posted by *Fatawan* /forum/post/0
> 
> 
> Thanks Terry--that makes perfect sense. How about something like 100% cotton that I could fire-treat myself?



My understanding is that self-treated fabric doesn't conform to building code. I know for sure that if a fire occurs in your home and the insurance company determines you have self-treated fabrics they won't pay out.


I'd be happier personally just spending the money to get pretreated, code-compliant, insurance company happy-fiying







fabrics.


-drin


----------



## BasementBob

drin:



> Quote:
> I'd be happier personally just spending the money to get pretreated, code-compliant, insurance company happy-fiying fabrics.



I thought for it to be code-compliant it was the assembly that had to be code compliant, not just the fabric.

(Although it's likely that if the fabric if flamable, so will be the assembly.)


----------



## ddingle

I am looking for a quick and cheap upgrade for bass response in a custom built theater. The budget ran out of gas and we compromised(did not use any) on bass traps. Now that we have things fired up somewhat,it seems even more important. I am going to use the Lexicon Equalizer built into their MC12,but I know some bass absorbtion would be valuable. I have a space behind the screen and front speakers that would allow me to stack a few big bags of fiberglass insulation or the like. It is going to be a GOM cover over the whole thing so aesthetics is not important. Am I going to buy anything?? Thanks for any input or suggestions.


----------



## Terry Montlick




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> drin:
> 
> 
> I thought for it to be code-compliant it was the assembly that had to be code compliant, not just the fabric.
> 
> (Although it's likely that if the fabric if flamable, so will be the assembly.)



If the fabric is mounted as a wall or ceiling covering, as specified in International Building Code 2003, section 803.4, then the fabric only is required to have been tested and given a Class A rating according to ASTM E 84. This will be true for typical permanently-installed fabric -- stapled over furring strings, or attached via a track fabric system.


If the fabric is mounted otherwise, as covering an acoustical panel, then NFPA 701 testing applies instead the the ASTM testing. That's where the "701" comes from in "Guilford FR701®," which is used a great deal for commercial acoustical panels. The entire assembly must be tested under NFPA 701, unless it covers less than 10% of the room wall and ceiling area (which would qualify it as a "decorative finish"). Technically, acoustical panel manufacturers must provide proof of this testing.


Regards,

Terry


----------



## Fatawan




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> If the fabric is mounted as a wall or ceiling covering, as specified in International Building Code 2003, section 803.4, then the fabric only is required to have been tested and given a Class A rating according to ASTM E 84. This will be true for typical permanently-installed fabric -- stapled over furring strings, or attached via a track fabric system.
> 
> 
> Regards,
> 
> Terry



Terry:


Interesting--that original fabric I was looking at says "Passes California Bulletin #117; ASTM E-84 adhered method Class I; NFPA 260, UFAC Class I. "


How does "Class A" compare to "Class I"?



Thanks.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Fatawan* /forum/post/0
> 
> 
> Terry:
> 
> 
> Interesting--that original fabric I was looking at says "Passes California Bulletin #117; ASTM E-84 adhered method Class I; NFPA 260, UFAC Class I. "
> 
> 
> How does "Class A" compare to "Class I"?



Different beasts entirely. One cannot substitute one for the other. ASTM E-84 is for building material flame spread and smoke development. NFPA 260 is for upholstered furniture fabric ignition from cigarettes.


Regards,

Terry


----------



## Fatawan

I asked this question in another thread, but I will repeat it here, where the acoustic folks hang! MY HT is a basement build, with 2 of 4 walls being concrete outside walls. In the rest of my basement that is finished, walls are first covered with a permeable foam board, which is sealed to the concrete, then a 1" air gap, then the 2x4 wall with R-13 fiberglass. I plan the same technique here. Since these walls are against concrete, do they need the whole DD+GG treatment? Any sound that "gets through" will then have to go up and through the floor upstairs to be heard. The joist will be filled with fiberglass insulation 1' thick, plus another 2" below that(ceiling will be suspended with the 2" RSIC clips). Just curious what the latest is on these basement walls.


----------



## Lindahl

I can get this locally:

http://www.jm.com/insulation/perform..._microaire.pdf 


How good would this material be compared to the popular OC703 for both treating first reflection points and making bass traps? It's type 475 and comes in 4x10x1" sheets with FSK. The absorption coefficients look close, but I couldn't find the density spec.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Lindahl* /forum/post/0
> 
> 
> I can get this locally:
> 
> http://www.jm.com/insulation/perform..._microaire.pdf
> 
> 
> How good would this material be compared to the popular OC703 for both treating first reflection points and making bass traps? It's type 475 and comes in 4x10x1" sheets with FSK. The absorption coefficients look close, but I couldn't find the density spec.



Type 475 = 4.75 pcf. This is about midway between OC703 and OC705, and should work fine for both functions. For early reflection and wideband absorption, you definitely want to have the FSK side so that it is *not* facing the room.


Regards,

Terry


----------



## ddingle




> Quote:
> Originally Posted by *ddingle* /forum/post/0
> 
> 
> I am looking for a quick and cheap upgrade for bass response in a custom built theater. The budget ran out of gas and we compromised(did not use any) on bass traps. Now that we have things fired up somewhat,it seems even more important. I am going to use the Lexicon Equalizer built into their MC12,but I know some bass absorbtion would be valuable. I have a space behind the screen and front speakers that would allow me to stack a few big bags of fiberglass insulation or the like. It is going to be a GOM cover over the whole thing so aesthetics is not important. Am I going to buy anything?? Thanks for any input or suggestions.



We added several bags of insulation behind the scrim wall. Used the auto equalization feature of the Lexicon. Ouila! Great bass! It is better near the microphone location,but functional in most seating locations.

I really like the Lexicon Eq feature. It makes us look good.


----------



## drunkpenguin

Hey guys, I just bought some owens corning ductliner, type 150 for use in my HT. I hope this stuff will work ok, I live in a small town and it is the only thing I could find. So from my reading I've concluded that I should cover the entire front wall with this stuff. Now the sidewalls I've read 42" and down. Would this be true for a 10' ceiling also? What about the back wall and the ceiling. Should anything be done there?


I also want to look into bass traps, is this something I need in each corner of the room? I generally see them placed up high in the corners, is there a method to determining where the traps would go?


----------



## Ethan Winer




> Quote:
> Originally Posted by *drunkpenguin* /forum/post/0
> 
> 
> I also want to look into bass traps, is this something I need in each corner of the room? I generally see them placed up high in the corners, is there a method to determining where the traps would go?



All corners are viable - where two walls meet, where a wall and ceiling meet, and even on the floor at the bottom of a wall. Three-way corners are especially prized. I have many traps in wall-floor corners.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *drunkpenguin* /forum/post/0
> 
> 
> Hey guys, I just bought some owens corning ductliner, type 150 for use in my HT. I hope this stuff will work ok, I live in a small town and it is the only thing I could find.



This is somewhat on the low density side. I wouldn't use less than a 2" thickness.



> Quote:
> So from my reading I've concluded that I should cover the entire front wall with this stuff. Now the sidewalls I've read 42" and down. Would this be true for a 10' ceiling also?



Yes, 42 is the answer. Don't forget to bring a towel!










Seriously, different rooms need different treatments. I routinely use side wall absorption right up to the ceiling. And of course the standard poly batting "diffusion" for the upper wall is really absorption anyway.


Regards,

Terry


----------



## drunkpenguin

Well, its what I've got to work with at this point. I am not going for a THX theater here I just want it to sound alot better than it does with 4 bare walls like I currently have. Plus I think the look of it really adds to a dedicated room. I guess I'll staple it up and do some sound testing.


Couple more questions..


I plan to have 2 rows of seating, the back seats on a riser (which I have not built yet), so should the side walls be treated higher near the back to compensate or will 42" accrost the board be good enough?


Next question, should any of this stuff go on the back wall at all or do I want to leave it untreated?


----------



## Terry Montlick

If you have depth on the front wall, a few inches of fiberglass thickness will do double-duty for reflections and bass absorption. I have also used the rear wall for bass absorption, but not without verifying that the back of the room will still be sufficiently "live" for the surround channels.


The thing about bass absorption, be it in the corners or on the walls, is that you need to cover a substantial area with the absorber. Little tri-corner absorbers won't make much difference.


Regards,

Terry


----------



## drunkpenguin

Terry, what do you mean if I have depth on the front wall? My room is 22x17x10.



If I use the stuff I bought, owens corning 150, and build 4 traps like the ones on this web page, will that help?

http://www.runet.edu/~shelm/acoustic...html#BassTraps


----------



## Terry Montlick




> Quote:
> Originally Posted by *drunkpenguin* /forum/post/0
> 
> 
> Terry, what do you mean if I have depth on the front wall? My room is 22x17x10.



Only that you will need 4" or more of depth from the surface of the absorber to the wall for significant bass absorption. With screen and seating requirements, this is sometimes too much to ask for.



> Quote:
> If I use the stuff I bought, owens corning 150, and build 4 traps like the ones on this web page, will that help?
> 
> http://www.runet.edu/~shelm/acoustic...html#BassTraps



Yes, it should make a significant difference! Floor to ceiling corner bass absorbers give you lots of depth in otherwise unused spaces. The WAF can be rather low, though.










Regards,

Terry


----------



## drunkpenguin

I don't have to deal with WAF, I have the luxury of having the GFDWIW (girlfriend does what i want) factor.










I am the king of my castle! But my castle lacks sound treatment and a moat! Sound treatment first, the moat is still being dug out, 1 shovel full at a time. Anyways, thanks for the help, Im going to get started today. Wish me luck!


----------



## Terry Montlick

Luck!


- Terry


----------



## drunkpenguin

Well I did a quick calculation and the amount of material I have would only only me to do the front wall, side walls, and 2 traps if I built them like the above link. I'd have to buy another 400 sq/ft roll just for 2 more traps. So, would 2 traps be ok or pointless?


What If I framed up the corners for a triangle and just shoved in whatever leftovers I have left, would that work or no? And lastly, I have a huge amount of pink wall insulation left over from building my house, could I utilize it in the traps or is it not dense enough?


----------



## Terry Montlick

One thing you can do is use (unfaced) fiberglass batting to fill space behind your more dense fiberglass. This often gives very good results. It alleviates the frequency "ripple" that you can get if you have just an airspace behind a layer of fiberglass absorption.


- Terry


----------



## drunkpenguin

I've started putting the stuff on the front wall. Wow what a difference already in echo reduction! How do you guys fasten this stuff to the wall and keep it smooth and flat without any dents? I've tried screws but they either create a dent or the head sticks out to far.


I also have a question about treating the side walls. I've been planning on ear level down but then I read about batting above that. What is that for? I would like to leave the top portion of the wall untreated for asthetic reasons. Will this still work ok?


----------



## Lindahl

Look at impaling cleats for hanging the fiberglass on the walls. They're flats of metal with screw holes and spikes on them. You screw the metal flats onto the wall, and impale the fiberglass on the spikes.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Lindahl* /forum/post/0
> 
> 
> Look at impaling cleats for hanging the fiberglass on the walls. They're flats of metal with screw holes and spikes on them. You screw the metal flats onto the wall, and impale the fiberglass on the spikes.



I've had mixed success with those, especially with thicker panels. My preference is to use these: http://www.rotofast.com/


----------



## drunkpenguin

Screws seem to be working ok if I drive them half way into the duct liner. If I get enough screws I don't think it will go anywhere. Plus the fabric will hold it on once up anyways i think.


New question, It looks like I'm going to have enough left over to cover the back wall from ear level down also. Asthetically this would look nice I think. Any positives or negatives to doing this vs leaving the wall drywall?


----------



## hardax

New question if I may (just posted this in the main forum but realize it is better suited here).


During really low bass moments I always hear rattling coming from my basement windows. Upon further investigation I see that it is the slats in between the panes of glass that are causing the rattle.


Since I can't really fix that short of getting new windows does anyone have any suggestions on how to dampen the bass hitting the windows?


I have heavy theater curtains covering the windows and bass traps in the corners with GIK panels on the walls already.


I was thinking of buying some OC703 insulation (4 inches thick?) and covering that with fabric - sort of like a big pillow and stuffing that into the window opening. Would that be effective in dampening the bass from reaching the window?


Any other suggestions would be much appreciated.


----------



## drunkpenguin

I am in no way an expert on sound but I do know somethings about construction and I'm guessing its the base on the walls that are vibrating the walls and causing your windows to shake. Kinda like when you slam the door and the window behind you rattles. I would think filling in the window with sound obsorbing material might stop the rattle sound from reaching your ears, even tho its still rattling. Maybe some ductliner or a whole bunch of wall insulation compressed together and fastened into the window frame?


Just a thought, maybe one of the pros can recomend a doodaddogimmic that will work better.


----------



## myfipie

Hardax,

Think of your window like a drum set. If the tones hits it then it will vibrate (raddle). If you put 703 on it then the raddling should stop.


Glenn


----------



## hardax

Thanks drunkpenguin and Glenn. Looks like we are all thinking on the same level.


One other question Glenn (or if Bryan is reading). Do I really have to worry about the material I use to cover the 703 in this application? I have some basic black fabric (old curtains) that I could use but wonder if I would be messing anyhing up acoustically?


Also, I am sure it has been covered here before but can anyone tell me where to get OC703? Searches seem to be coming up short.


----------



## pepar




> Quote:
> Originally Posted by *hardax* /forum/post/0
> 
> 
> 
> Also, I am sure it has been covered here before but can anyone tell me where to get OC703? Searches seem to be coming up short.



Many sharp shoppers buy their acoustical insulation from this company . These materials are generally made for insulating/quieting HVAC ducts and the best prices can always be had when one buys close to the source. All of the commercially available acoustical absorption products for home theater start with these materials.


----------



## Terry Montlick

The fabric *can* make a difference acoustically. Tight-weave fabrics can reflect high frequencies, making them less able to pass sound through to be absorbed. You are then reducing the absorber's efficiency.


On the other hand, some highs will get through virtually any fabric, so it is a matter of degree. If you don't know what fabric you have, you are taking pot luck.


Regards,

Terry


----------



## tonybradley




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> The fabric *can* make a difference acoustically. Tight-weave fabrics can reflect high frequencies, making them less able to pass sound through to be absorbed. You are then reducing the absorber's efficiency.
> 
> 
> On the other hand, some highs will get through virtually any fabric, so it is a matter of degree. If you don't know what fabric you have, you are taking pot luck.
> 
> 
> Regards,
> 
> Terry



I'm using Felt over my 2" rigid fiberplass panels. Do you find that acceptable? I originally used Muslin, but felt (pun) it was ugly, so I changed it to felt. It could be me, but it appears that I don't have as much absorption now as when the Muslin was over the panels. I'm wondering if Felt is acceptable, or if I should re-wrap my panels (located at the 1st reflection points) with GOM?


----------



## pepar




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> I'm using Felt over my 2" rigid fiberplass panels. Do you find that acceptable? I originally used Muslin, but felt (pun) it was ugly, so I changed it to felt. It could be me, but it appears that I don't have as much absorption now as when the Muslin was over the panels. I'm wondering if Felt is acceptable, or if I should re-wrap my panels (located at the 1st reflection points) with GOM?



You might have increased absorption at some lower frequencies by adding a "diaphram", but felt is NOT acoustically transparent, so you've decreased the overall effectiveness of your absorbers. Why not just bite the bullet and buy the RIGHT product for the job - Guilford of Maine FR701???


----------



## myfipie




hardax said:


> Thanks drunkpenguin and Glenn. Looks like we are all thinking on the same level.
> 
> 
> One other question Glenn (or if Bryan is reading). Do I really have to worry about the material I use to cover the 703 in this application? I have some basic black fabric (old curtains) that I could use but wonder if I would be messing anyhing up acoustically?
> 
> 
> QUOTE]
> 
> 
> The thing to do is to use open celled fabric. So if you can blow through it you should be fine. If you are only trying to focus on the low end that it really is not going to matter to much. Bass will go right through it.
> 
> 
> Glenn


----------



## Fatawan

Question:

http://www.bobgolds.com/AbsorptionCoefficients.htm From Bob's site, it would appear that UltraTouch Cotton batts(Bonded Logic, near the end) would make a great insulation to fill theater walls vs. fluffy pink fiberglass. It is a great absorber, all the way down to 125Hz. I wonder how well it does even lower? Is it worth using? All opinions welcome. An R-13 batt is not as expensive as I thought.


----------



## BasementBob

Fatawan


re Utratouch cotton:


R-13 3.5" (mm) A 0.95 1.30 1.19 1.08 1.02 1.00 1.15


It's often mentioned when people start talking about avoiding man-made fibers.


But I was watching Holmes On Homes Pasadena part 2 and heard a couple of things:


1) They used to dilute boric acid in water, and use it to wash newborn babies eyes out in hospitals with it

2) The boric acid is added to make it a class A fire retardant material

3) As a side benefit it repells all the insects you might encounter. Termites will not live in it. Repells mice and roof rats.

4) The boric acid, because of the acidic environment mold will not grow in it. If you get this wet and dry and wet and dry 50 times, it'll dry out because cotton breaths and gives off the water, but you'll never have mold or mildew.

5) environmentally friendly (recycling blue jeans)


----------



## tonybradley




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> You might have increased absorption at some lower frequencies by adding a "diaphram", but felt is NOT acoustically transparent, so you've decreased the overall effectiveness of your absorbers. Why not just bite the bullet and buy the RIGHT product for the job - Guilford of Maine FR701???




Because I was told by folks on this forum that for absorption (such as panels at the first reflection points), your fabric didn't need to be "acoustically transparent" and that was more for covering your speakers, etc. However, once I changed to felt, it appears I lost some absorption I had when I used Muslin. I wanted to check in again to see if Felt was 'OK' to use to cover Rigid Fiberglass at the First Reflection points. GOM is expensive for me, and when I found out Felt would be ok, that was good for me as it was less expensive. I wanted to find out if someone can tell me "Technical Reasons" why felt would be good or bad to cover broadband absorption panels.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Fatawan* /forum/post/0
> 
> 
> Question:
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm From Bob's site, it would appear that UltraTouch Cotton batts(Bonded Logic, near the end) would make a great insulation to fill theater walls vs. fluffy pink fiberglass. It is a great absorber, all the way down to 125Hz. I wonder how well it does even lower? Is it worth using? All opinions welcome. An R-13 batt is not as expensive as I thought.



It won't help or hurt as wall cavity insulation. Any low-density porous absorber will work as well. There really isn't any way to get improved performance for this function.


Regards,

Terry


----------



## Fatawan




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> It won't help or hurt as wall cavity insulation. Any low-density porous absorber will work as well. There really isn't any way to get improved performance for this function.
> 
> 
> Regards,
> 
> Terry



Ok--thanks Terry---fluffy pink fiberglass it is then! I am saving money left and right!


----------



## John Ballentine

What's the best way to attach 4'X8' fabric wrapped panels to the ceiling? Can't screw or nail them as this will ruin the fabric I have chosen (which is black speaker grill cloth).

The panels are only 1/2" thick - so Rotofast Snap-on anchors won't work. Glue? Liquid nails?

And what spray on adhesive works best to ensure the fabric doesn't come loose?

Thanks for your help.


----------



## pepar




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Because I was told by folks on this forum that for absorption (such as panels at the first reflection points), your fabric didn't need to be "acoustically transparent" and that was more for covering your speakers, etc. However, once I changed to felt, it appears I lost some absorption I had when I used Muslin. I wanted to check in again to see if Felt was 'OK' to use to cover Rigid Fiberglass at the First Reflection points. GOM is expensive for me, and when I found out Felt would be ok, that was good for me as it was less expensive. I wanted to find out if someone can tell me "Technical Reasons" why felt would be good or bad to cover broadband absorption panels.



I'd be interested in being pointed to a post where someone said broadband absorbers didn't need to be covered with acoustically transparent material. As your ears have told you, you've lost absorption because the felt is reflecting some frequencies instead of allowing them to pass and be absorbed. GOM certainly is expensive and I understand your desire to find a lower cost alternative that meets your aesthetic sensibilities. As for technical reasons that give the thumbs up or down on felt, see Glenn's post above .


----------



## McCall

As to fabric adheavsive Super 77. As to nails or screws, You certanly CAN screw through it. you simply punch a hole first. there are various caps you can put on screws as well.


----------



## pmeyer




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Because I was told by folks on this forum that for absorption (such as panels at the first reflection points), your fabric didn't need to be "acoustically transparent"



I have seen similar things posted, but you have to be careful. I can see three categories of cloth:


1) Acoustically Transparent:

All (most) sound gets through, any slight absorption is even across frequencies so it won't color your sound.


Uses: covering speakers, covering broadband or mid-high frequency absorbing wall treatments.


Examples: speaker cloth, good AT screen material, some types of GOM.


2) Acoustically non-reflective:

Very little sound is reflected from the cloth. However, some sound may be absorbed by the cloth and not make it out the other side. This would color your sound if put in front of speakers.


Uses: fine for covering treatments.


3) Acoustically reflective:

Reflects significant sound energy back into the room at some frequencies (typically mid to high frequencies are reflected, bass gets through). Sometimes this is what you want (to cover a bass trap if you have enough high frequency absorption.)


So, while it may be true that speaker-cloth quality acoustically transparent cloth isn't needed on your first reflection points, anything that reflects mid-high frequencies defeats the purpose of the panels. Your ears are telling you that the felt is doing that. Trust your ears and switch to GOM or some less expensive non-reflective fabric (muslin, etc.)


----------



## Fatawan

Where do you think 100% cotton would fall in this list of cloth categories?


----------



## tonybradley




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> I'd be interested in being pointed to a post where someone said broadband absorbers didn't need to be covered with acoustically transparent material. As your ears have told you, you've lost absorption because the felt is reflecting some frequencies instead of allowing them to pass and be absorbed. GOM certainly is expensive and I understand your desire to find a lower cost alternative that meets your aesthetic sensibilities. As for technical reasons that give the thumbs up or down on felt, see Glenn's post above .



I'll do some searches and post the links. I was told by a few of the "Acoustic Gurus" on the forum that Felt would be perfectly acceptable for broadband absorption. But, as you pointed out, it does sound different to me in comparison to the ugly muslin I was using. For the price I spent for the Muslin, the dye, and now the felt, I could have purchased the GOM. Price lesson learned I guess.


----------



## tonybradley

As requested, here is the thread regarding the use of Felt:

http://www.avsforum.com/avs-vb/showt...highlight=felt


----------



## pepar




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> As requested, here is the thread regarding the use of Felt:
> 
> http://www.avsforum.com/avs-vb/showt...highlight=felt



There is conflicting information there and, IMO, Bryan's post is at conflict internally. For an absorber to be broadband, it must receive the broadest band of frequencies. Cloth that is not acoustically transparent, and does not outright absorb what it does not pass, will reflect. Therefore, the underlying absorptive material will not do it's thing on those frequencies. Perhaps the different posters in that thread are not on the same page. Anyway, if felt is not appropriate to use in front of speakers, it is not appropriate to use to cover _broadband_ absorbers.


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Anyway, if felt is not appropriate to use in front of speakers, it is not appropriate to use to cover _broadband_ absorbers.



I will agree that if felt _reflects_ some sound energy back into the room, it is not appropriate for first reflection point treatment coverage.


I disagree that the material used on broadband absorbers must be appropriate for use in front of speakers. In speaker covering cloth there should be very little absorption. In broadband absorber covering cloth, absorption is just fine, as long as there is no reflection/diffusion of sound energy back into the room.


That said, it's definitely safer to go with AT material. You can get data on acoustic transparency. I haven't seen a lot of data on acoustic reflectivity across frequencies.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> I will agree that if felt _reflects_ some sound energy back into the room, it is not appropriate for first reflection point treatment coverage.
> 
> 
> I disagree that the material used on broadband absorbers must be appropriate for use in front of speakers. In speaker covering cloth there should be very little absorption. In broadband absorber covering cloth, absorption is just fine, as long as there is no reflection/diffusion of sound energy back into the room.
> 
> 
> That said, it's definitely safer to go with AT material. You can get data on acoustic transparency. I haven't seen a lot of data on acoustic reflectivity across frequencies.



Ahh yes, I see the distinction now. Transmission good. Absorption good. Reflection bad.


Couldn't one derive reflectivity by frequency by looking at NRC and STC? If it's not absorbed and not transmitted, it is reflected?


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Ahh yes, I see the distinction now. Transmission good. Absorption good. Reflection bad.
> 
> 
> Couldn't one derive reflectivity by frequency by looking at NRC and STC? If it's not absorbed and not transmitted, it is reflected?



To add to the complexity: if it reflects the energy back, but in a diffuse way (diffuse reflection as opposed to specular reflection), it might still be ok for first reflection points. The mid-high energy will still be in the room, but will not arrive at the listener's ears as a short-delay echo that would affect localization.


I'd stick with GOM, or go with the 'if you can breathe through it relatively easily it's ok' test.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> 
> I'd stick with GOM, or go with the 'if you can breathe through it relatively easily it's ok' test.



I like that; everyone has the necessary gear to do that test.


----------



## Ethan Winer

Paul,



> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> if it reflects the energy back, but in a diffuse way (diffuse reflection as opposed to specular reflection), it might still be ok for first reflection points.



Just to be clear, nothing as thin as cloth can offer a useful amount of diffusion.


--Ethan


----------



## tonybradley

So,


Should I rip my felt off my first reflection absorption panels and use something else? I'm receiving conflicting information. I was told a while back that Felt would be fine, but am now reading that it probably isn't for the use of covering absorption panels at the first reflection. Does Felt reflect too much sound back into the room, making my panels ineffective at high frequencies? I respect everyone's replies and suggestions, but please note that I was told by two well respected folks in this thread that Felt was fine, so I ask that you aren't harsh to me. I just DON'T KNOW the answers and am willing to follow the suggestions of those that do.


----------



## pmeyer




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Just to be clear, nothing as thin as cloth can offer a useful amount of diffusion.
> 
> --Ethan



Thanks. When I think about the depth requirements for the quadratic residue diffusors to get any useful frequency range, that makes sense.


----------



## pmeyer

Tony,


A few things are clear:


1) first reflection point treatment should not reflect mid-high sound.


2) When you switched from muslin to felt on your first reflection points you did not like the change in the sound.


Assuming nothing else changed, that could indicate that the felt was reflecting more high frequency sound than the muslin was. As muslin is a very open weave and felt is denser, this is plausible.


I don't think you are getting any conflicting advice at this point: if the felt sounds worse than the muslin, switch to a more open fabric. What sounds good to you in your room always trumps any theoretical advice you get.


The fact that previous advice indicated felt would be ok is irrelevant. Perhaps there are different thicknesses/densities/types of felts. Maybe some pass sound better than others. Maybe felt doesn't pass high freq sound and the advice was bad. It doesn't much matter. I'm sure the advice was given in good faith.


Bite the bullet and try again. Let us know what you end up with and whether it works better.


----------



## Terry Montlick




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> So,
> 
> 
> Should I rip my felt off my first reflection absorption panels and use something else? I'm receiving conflicting information. I was told a while back that Felt would be fine, but am now reading that it probably isn't for the use of covering absorption panels at the first reflection. Does Felt reflect too much sound back into the room, making my panels ineffective at high frequencies? I respect everyone's replies and suggestions, but please note that I was told by two well respected folks in this thread that Felt was fine, so I ask that you aren't harsh to me. I just DON'T KNOW the answers and am willing to follow the suggestions of those that do.



Felt reflects significantly above around 2 kHz. It should *not* be used to cover broadband absorbers. Sometimes free advice is worth exactly that.










Yes, I'm afraid you need to remove the felt and replace it with a much more acoustically transparent fabric.


Regards,

Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Yes, I'm afraid you need to remove the felt and replace it with a much more acoustically transparent fabric.



I wouldn't be so quick to have Tony go to all that trouble. Maybe some felt reflects, but the stuff I've seen does not.


Tony, try this simple test: Stand in front of one of your panels and "talk into" it. Does it sound like you're talking into a total void? If so, then the felt is probably fine. If you still have some raw fiberglass, use that as a comparison. If they both sound the same, then the felt is fine. If you hear more of your voice coming back on the panel with felt, then you must have bought some of that "reflective felt" Terry is referring to.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> Thanks. When I think about the depth requirements for the quadratic residue diffusors to get any useful frequency range, that makes sense.



Exactly.


----------



## BasementBob

Felt, contact with wall, absorption coefficients

125hz 0.13

250hz 0.41

500hz 0.56

1000hz 0.69

2000hz 0.65

4000hz 0.49


At low frequencies, low absorption coefficients might mean that the sound is going right through it.

At high frequencies, low absorption coefficients mean that the sound is reflecting off it. In this case, at 4000hz, according to that test, more than half the sound energy is reflecting off the felt.



> Quote:
> Early reflections are defined as reflections from boundary surfaces or other surfaces in the room which reach the listening area within the first 15 ms after the arrival of the direct sound. The levels of these reflections should be at least 10 dB below the level of the direct sound for all frequencies in the range 1 kHz to 8 kHz.
> 
> 
> from: EBU Tech. 3276



50% of the energy is 3dB

90% of the energy is 10dB


----------



## tonybradley




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> I wouldn't be so quick to have Tony go to all that trouble. Maybe some felt reflects, but the stuff I've seen does not.
> 
> 
> Tony, try this simple test: Stand in front of one of your panels and "talk into" it. Does it sound like you're talking into a total void? If so, then the felt is probably fine. If you still have some raw fiberglass, use that as a comparison. If they both sound the same, then the felt is fine. If you hear more of your voice coming back on the panel with felt, then you must have bought some of that "reflective felt" Terry is referring to.
> 
> 
> --Ethan



Thanks Ethan. I can definitely tell a difference when talking into my felt covered fiberglass than say, the wall. However, I haven't tried to test between the felt covered fiberglass and fiberglass in general. Not sure why I didn't think of it. I do have a few pieces of rigid boards left. I'll do this simple test today and see how it fairs. Thanks!!!


----------



## Ethan Winer

Bob,


> At high frequencies, low absorption coefficients mean that the sound is reflecting off it. In this case, at 4000hz, according to that test, more than half the sound energy is reflecting off the felt.


----------



## pepar




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> Thanks Ethan. I can definitely tell a difference when talking into my felt covered fiberglass than say, the wall. However, I haven't tried to test between the felt covered fiberglass and fiberglass in general. Not sure why I didn't think of it. I do have a few pieces of rigid boards left. I'll do this simple test today and see how it fairs. Thanks!!!



Get someone to snap your picture when you're talking to your acoustical treatments. This could really be helpful to others.


----------



## Parkytivo

I have 2 windows on each side of my 118" Carada theater screen. What would be the easiest way or cost effective way to treat/cover this area. I know the search function is my friend but my father in-law just passed away unexpectantly and we have family coming in. I want to get it up and running as this is a new build and I don't have a lot of time. I am having a hard time thinking straight. I would like to be able to take their minds off of the situation. Thanks for any suggestions.


----------



## pepar




> Quote:
> Originally Posted by *Parkytivo* /forum/post/0
> 
> 
> I have 2 windows on each side of my 118" Carada theater screen. What would be the easiest way or cost effective way to treat/cover this area. I know the search function is my friend but my father in-law just passed away unexpectantly and we have family coming in. I want to get it up and running as this is a new build and I don't have a lot of time. I am having a hard time thinking straight. I would like to be able to take their minds off of the situation. Thanks for any suggestions.



Depends on how permanent you want the coverings to be. In a similar situation, I installed strips inside the window "well" leaving 3/4" space between them and the wall surface. I then screwed particle board to the strips for a flush covering and went on about my business of adding acoustical treatments.


----------



## eugovector

Light blocking drapes from Bed, Bath, Beyond, target, walmart or the like. Unless you're going to make fiberglass plugs/panels for the windows, which will render them usless as windows until you remove the panel plug.


You can still treat below the screen, and @ first reflection points, but it sounds like you have a lot on you plate. Go with the curtains, and worry about the rest later.



> Quote:
> Originally Posted by *Parkytivo* /forum/post/0
> 
> 
> I have 2 windows on each side of my 118" Carada theater screen. What would be the easiest way or cost effective way to treat/cover this area. I know the search function is my friend but my father in-law just passed away unexpectantly and we have family coming in. I want to get it up and running as this is a new build and I don't have a lot of time. I am having a hard time thinking straight. I would like to be able to take their minds off of the situation. Thanks for any suggestions.


----------



## tonybradley




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Get someone to snap your picture when you're talking to your acoustical treatments. This could really be helpful to others.



LOL!! I made sure I did this test with the door to the HT closed







It was too dark in the room to take a good pic anyway..heheheh.


Seriously though, I did try testing between the Fiberglass wrapped with Felt and a piece of plain rigid fiberglass (both 2", 3pcf). When talking into them, I heard no discernable difference to my ear in regards to any sound bouncing back to me. I used standard Felt from Joanne Fabrics, so I'm not sure the thickness of it.


----------



## pepar




> Quote:
> Originally Posted by *tonybradley* /forum/post/0
> 
> 
> LOL!! I made sure I did this test with the door to the HT closed
> 
> 
> 
> 
> 
> 
> 
> It was too dark in the room to take a good pic anyway..heheheh.
> 
> 
> Seriously though, I did try testing between the Fiberglass wrapped with Felt and a piece of plain rigid fiberglass (both 2", 3pcf). When talking into them, I heard no discernable difference to my ear in regards to any sound bouncing back to me. I used standard Felt from Joanne Fabrics, so I'm not sure the thickness of it.



I'm a believer in using one's ears to detect gross problems and differences in sound, but maybe the speaking into the absorber wasn't valid test in this situation. More likely in my mind, based on what Terry posted re felt reflecting above 2k, your voice doesn't produce the frequency range where the felt falls down as an absorber covering.


----------



## Terry Montlick

Talking is not a good test for fabric transparency. Reflection from fabric typically occurs at high frequencies (2-3 kHz and above). However most speech sounds -- the voiced ones (i.e. vowels) -- are below this. The unvoiced sounds, like the fricative  and the plosive [t], extend to this higher frequency range. But their timbre qualities may not be easily discerned from talking to a wall.


If you want to do a real test, use a program like ETF or REW (free!). Put your mic at the listening position (though remove any seating right there). Directing the test signal to a single main speaker, take one wideband measurement with the felt absorber covering, and one without, and don't change anything else. Set a time slice (windowed frequency response) after the initial impulse, but including this first reflection off the fiberglass or fiberglass-felt combination. Overlaying these graphs should show pretty clearly the reflection effects of your felt.


Regards,

Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Talking is not a good test for fabric transparency. Reflection from fabric typically occurs at high frequencies (2-3 kHz and above). However most speech sounds -- the voiced ones (i.e. vowels) -- are below this.



Terry, I suggest you record yourself speaking normally, then use an EQ to boost frequencies above 3 KHz and report back what you hear. If you hear no change (implying no content above 3 KHz) I'll be astonished.



> Quote:
> If you want to do a real test, use a program like ETF or REW (free!).



Agreed. I already did that. Below is a pair of graphs showing the response with and without one inch thick 705 rigid fiberglass covered with 1/16th inch felt at nearby side-wall reflection points.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Agreed. I already did that. Below is a pair of graphs showing the response with and without one inch thick 705 rigid fiberglass covered with 1/16th inch felt at nearby side-wall reflection points.



No. That is the wrong experiment! In order to see the effect of felt, you need to change just this variable, leaving the fiberglass in place. You also need to set the analysis window so that it only sound during the reflection delay is used.


- Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry, I suggest you record yourself speaking normally, then use an EQ to boost frequencies above 3 KHz and report back what you hear. If you hear no change (implying no content above 3 KHz) I'll be astonished.



I did NOT say there was no content above 3 kHz. Please read what I posted again. And again, if necessary.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Terry, I suggest you record yourself speaking normally, then use an EQ to boost frequencies above 3 KHz and report back what you hear. If you hear no change (implying no content above 3 KHz) I'll be astonished.



Perhaps that's why Terry said "However most speech sounds -- the voiced ones (i.e. vowels) -- are below this. The unvoiced sounds, like the fricative  and the plosive [t], extend to this higher frequency range. But their timbre qualities may not be easily discerned from talking to a wall." Besides, just how one would boost their 3k and up vocal content while speaking into their absorbers escapes me. Sheesh.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> I did NOT say there was no content above 3 kHz. Please read what I posted again. And again, if necessary.
> 
> 
> - Terry



I know you can defend yourself, but I couldn't resist.


----------



## tonybradley

What if I have my 2 year old scream really loud into the treatments? I have a feeling some of those squeels are over 4KHz. LOL!!!! Kidding.


I guess for me, what I can do (I know this isn't very technical) is to listen to a few movie soundtracks I'm familiar with, with the felt on. Take the felt off all the panels and do another listen. It may be a conincidence, but I do hear a difference in my treatments after I placed felt on them from the Muslin I had prior, but no real tests were peformed. If it sounds much better to me with the felt off the treatments, I'll know the felt is not for me and replace them with GOM. If I'm unable to determine a difference in the sound, then I'll put the felt back over my treatments and save my cash.


----------



## krasmuzik

Crying babies are at 4kHz. This is why many speakers are not accurate and reduce that range - they know the men buying them don't want to really hear crying babies accurately.


----------



## tonybradley




> Quote:
> Originally Posted by *krasmuzik* /forum/post/0
> 
> 
> Crying babies are at 4kHz. This is why many speakers are not accurate and reduce that range - they know the men buying them don't want to really hear crying babies accurately.



Maybe that's why my wife wondered why I occasionally yelled for her to get up when I was listening to a sountrack.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> No. That is the wrong experiment! In order to see the effect of felt, you need to change just this variable, leaving the fiberglass in place. You also need to set the analysis window so that it only sound during the reflection delay is used.



Of course, but my graph shows that normal felt is fine. Which is the real issue. BTW, one of your pals is arguing on another forum that silk and other tight weave fabrics are fine for first reflection treatment. I can't agree with that, but felt is fine. You don't like felt? No problem. Don't use it!










--Ethan


----------



## BasementBob

krasmuzik:



> Quote:
> Crying babies are at 4kHz.



I believe babies are loudest between 2khz and 4khz -- and have a scream/cry frequency/volume distribution roughly the equivilent of an inverted Fletcher-Munson curve ( or your pick of any equal-loudness contour: Robinson-Dadson, ISO 226:2003 ). Evolution has made the loudest thing we can hear, a baby's cry.


----------



## Stew4msu

OK, several of what might be more questions for some kind soul:


1. I want to add some treatments to my front wall. However, my front wall is a bit unusual (see picture). I plan on treating the exposed front wall (around the screen), but should I also treat the angled ceiling/wall where the speakers are? In case it's hard to tell in the photo, the front wall is 8' high and then the wall slopes up to the 10' ceiling. I put my speakers on that slope and they're naturally angled right at the seating area. If I should treat that angled wall/ceiling, how do I do that with the speakers there? If it matters, the rear speakers are at about 7' high.


2. Using the reflection point calculator, my reflection points are quite high (due to the speaker placement), so is there any need to treat the walls below 44" (ear height), or should I just put some panels along the wall where the actual reflection points are (and I'll probably remove the posters that are visible in the third picture)?


3. The wall in the rear of the room is the same as what you see in the front (wall slopes up to meet the ceiling). How do I do a floor to ceiling bass trap in that case (was thinking about the stacked triangle thingamagigs)? Or should I just put an 8' tall bass trap?


4. Due to the equipment/DVD storage shown in the pic, I can't but a bass trap there. I was going to do both back corners, should I do the other front as well? There's open space behind the equipment/DVD storage (about 1.5' deep - see second pic). Should I put bass traps in those corners (there's 2 of them)?


5. I currently have a chair rail around the room (see third pic) with fabric underneath. I have no idea if the fabric is accoustically transparent, reflective or what. When I built the room, I didn't want the fabric right against the wall, so I put extra carpet padding behind it (the 1/2" thick blue stuff - see fourth pic and pardon the quality of the pic). Is that good, bad or indifferent?


I should add that to my ears the room sounds good right now. With no treatments at all, it's very pleasant and everyone raves about it. However, sometimes it seems that dialogue is a bit hard to hear (reflections?) and the bass seems a bit "rattley" from time to time, so I'm looking to make some improvements.







































Thanks


----------



## Ethan Winer

Stew,



> Quote:
> I want to add some treatments to my front wall.



Looking at your setup I'd say you need corner bass traps and side wall first reflection treatment much more than absorption on the front wall.



> Quote:
> I put my speakers on that slope and they're naturally angled right at the seating area.



Any chance to change that? All speakers should be at ear level for best results.



> Quote:
> or should I just put some panels along the wall where the actual reflection points are



Yes.



> Quote:
> Due to the equipment/DVD storage shown in the pic, I can't but a bass trap there.



Then put a trap flat on the front wall, as near to the corner as you can.



> Quote:
> I should add that to my ears the room sounds good right now. With no treatments at all, it's very pleasant and everyone raves about it. However, sometimes it seems that dialogue is a bit hard to hear (reflections?) and the bass seems a bit "rattley" from time to time, so I'm looking to make some improvements.



Imagine how great it will sound once it's treated properly!










--Ethan


----------



## Mr.Tim




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> If the fabric is mounted as a wall or ceiling covering, as specified in International Building Code 2003, section 803.4, then the fabric only is required to have been tested and given a Class A rating according to ASTM E 84. This will be true for typical permanently-installed fabric -- stapled over furring strings, or attached via a track fabric system.



True, but where the International Residential Code has been adopted, and the home theater is in a 1 or 2 family or townhome, a Class C rating (200 flame spread) is required. R315. However, as you stated, the testing is required.


You cannot treat with a home-grown solution (eg boric acid) for a compliant installation. You could ask the building official about a product listed for the use (eg fabric shield). Probably not worth the effort.


The fabric is an interior finish, not part of an assembly. The listing of a the fabric alone should be sufficient.


(not all of this pertains to you, Terry-- just answering a few of the questions that came up)


Regards,

Tim


----------



## McCall

I have a question for you AT experts here, I mean the ones making a living at it, I have two panels in my theater that I covered with felt early on. my others are covered with Stetch velvet that You can easily blow through, yeah I know not a perfect test but has worked great for me, but that is not the issue I am asking about.

the other day I walked very close to each panel the velvet and the felt. Nothing going on in theater at the time, meaning no sound on. when I was close to the velvet covered the everything sounded exactly the same as if I were feet away in the room, but when I walked near the felt covering there was a very perceptible deadening sound change, I mean just the ambient sound of the room itself, nothing on whatever, no fans no AC etc. just different degrees of silence.

What would that indicate with regard to the felt in this case over the velvet?

I found it so strange that I just wondered if you guys could tell me.


----------



## Ethan Winer




> Quote:
> What would that indicate with regard to the felt in this case over the velvet?



If you hear more of a drop in ambient sound level as you approach a panel, that implies more absorption. A better test is to "talk into" each panel and see how dead your voice sounds coming back. If you do that with a bare wall first you'll have something to compare to. After a while you can tell easily which materials absorb (voice frequencies) better than others.










--Ethan


----------



## tonybradley




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> If you hear more of a drop in ambient sound level as you approach a panel, that implies more absorption. A better test is to "talk into" each panel and see how dead your voice sounds coming back. If you do that with a bare wall first you'll have something to compare to. After a while you can tell easily which materials absorb (voice frequencies) better than others.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



This is basically what you told me, and others discarded it. Now that you were more detailed in saying it's easy to determine which materials absorb "Voice Frequencies", can we get a little more detailed on which is better for an HT environment, since most of us aren't building one for poetry readings? No disrespect, it's just tough to swallow so many different views. Is there a chart that shows reflective coefficients of various materials (felt, Muslin, Cotton, Velvet, different types of GOM, etc.) when covering absorption material? Otherwise, unless a person spends a great deal of money and time experimenting, we will go into this blindly. I Understand people such as myself could have went with GOM in the first place, and in hind sight, I should have from the time and money I've spent changing out my muslin for felt. But, with all the knowledge around this forum, and true tests that have been done, I'd like to know more about the Plus and Minus of felt outside the voice range. Again, this is of no disrespect to you as I have read many of your posts and I thank you for the wealth of knowledge. Nobody really discards GOM, but some are discarding Felt, and would be good to know how it will really affect my room. In movie soundtracks, is there a lot of information over the 4khz frequencies that felt supposedly reflects, etc.


----------



## Terry Montlick

Tony,


Here's an ancient graph for felt absorption/reflection/transmission, which I found in my files:











Sorry that I don't have time right now to do some modern tests for you. This is from a 1916 paper by F.R. Watson, "An Investigation of the Transmission Reflection and Absorption of Sound by Different Materials." It may in fact be the oldest journal paper I have!


The felt was hair felt, which would probably be hard to find an exact match for today. Heck, the anechoic wedge tables that Leo Beranek published in the 1940's became obsolete soon after, when the flow resistivity for 3 pcf fiberglass completely changed. The felt thickness layer units are 1/2".


There are a couple of things to notice:

The reflection component is significant.

It does not change nice and linearly with thickness.


Different felt materials will no doubt behave differently. This is the main reason for going with a known material like GOM fabric.


Regards,

Terry


----------



## Stew4msu

Thanks Ethan for your response.



> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Looking at your setup I'd say you need corner bass traps and side wall first reflection treatment much more than absorption on the front wall.



I plan on doing that too, should I not do the front wall as well? If I do, should I treat the angled wall too?



> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Any chance to change that? All speakers should be at ear level for best results.



Probably not, it's a sacrifice I had to make.



> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Then put a trap flat on the front wall, as near to the corner as you can.



I might not have the room for his either, due to the amount of space between the screen and the equipment rack. Would it not be beneficial to put some type of bass trap behind the DVD/equipment storage. It's just a cavity back there and the built in DVD storage is just made out of 2X6's with plywood backing.


What about where the wall corners hit the angled ceiling/wall in the front and back? I can't really to floor to ceiling, because of the angle. Just make the bass traps 8' high?



Thanks,


Stew


----------



## uxbridge

Does anyone know of a calculator/spreadsheet that you can input your room size and your acoustical treatments specs. to determine how much you will need to reach the RT60 you desire? Thanks in advance.


Bill


----------



## Phil Olson

The problem is that you have to account for all the 'natural' treatments like couches, rugs, shelving, windows, even people, in addition to the room size.


If you want to do better than just ballpark standard treatments like front wall/lower half of side walls, etc., pick up a copy of ETFA and measure where you are. You can then ask what treatments to add for any deficiencies you may find.


----------



## pepar




> Quote:
> Originally Posted by *uxbridge* /forum/post/0
> 
> 
> Does anyone know of a calculator/spreadsheet that you can input your room size and your acoustical treatments specs. to determine how much you will need to reach the RT60 you desire? Thanks in advance.



Be prepared to be daunted; the more accurate detail you feed it, the more accurate will be the results. Phil's right about simply getting some free software, a mic and a laptop and actually measuring, but here ya go . _Prepare to be daunted!_


----------



## Ethan Winer

Tony,



> Quote:
> can we get a little more detailed on which is better for an HT environment, since most of us aren't building one for poetry readings?



For panels at reflection points you want the absorption to be as high as possible at all frequencies. It's that simple.



> Quote:
> No disrespect, it's just tough to swallow so many different views.



I agree fully, and that's the main problem with this thread. It's too long, it's full of conflicting opinions expressed by experts and newbies alike, yet it's stuck at the top so people feel they need to read and understand it all. Nobody can understand it all because much of it is not understandable. And much of it is wrong.



> Quote:
> Is there a chart that shows reflective coefficients of various materials (felt, Muslin, Cotton, Velvet, different types of GOM, etc.) when covering absorption material?



Not that I know of. Even if there were such a thing, its value would be limited. For example, Terry's graph is really neat from a historical perspective, but nobody makes felt from horse hair today, and nobody uses 1/2 inch thick felt over rigid fiberglass. Likewise for cotton. There's a lot of ways to make cotton fabric, and they're not all equivalent acoustically.


All that said, in my experience typical 1/16th inch felt is fine.










--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Here's an ancient graph for felt absorption/reflection/transmission, which I found in my files



Very cool! Thanks for posting that.



> Quote:
> The reflection component is significant.



It sure is. Now, if only there were an axis showing frequency this would actually be useful information.










Useful for half inch thick horse felt, that is!










--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *Stew4msu* /forum/post/0
> 
> 
> I plan on doing that too, should I not do the front wall as well? If I do, should I treat the angled wall too?



I won't say don't treat the front wall, but it's less important than other places in the room. Also, treating a room is often an ongoing process, especially for DIY'ers. You start with a few panels, and see what that does, then you're in a better position to know what else is needed.



> Quote:
> What about where the wall corners hit the angled ceiling/wall in the front and back? I can't really to floor to ceiling, because of the angle. Just make the bass traps 8' high?



The more bass trapping the better. Always.


--Ethan


----------



## pepar

Other than Linus Van Pelt, I've never seen anyone hang onto a piece of cloth so tightly.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Now, if only there were an axis showing frequency this would actually be useful information.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Useful for half inch thick horse felt, that is!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Would pass your criticisms on to the paper's author, Floyd R. Watson (first editor of JASA), but he died in 1974.










- Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> Would pass your criticisms on to the paper's author, Floyd R. Watson (first editor of JASA), but he died in 1974.



I'm not criticizing at all! I think it's really cool. Just irrelevant today.










--Ethan


----------



## Stew4msu




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> I won't say don't treat the front wall, but it's less important than other places in the room. Also, treating a room is often an ongoing process, especially for DIY'ers. You start with a few panels, and see what that does, then you're in a better position to know what else is needed.
> 
> 
> --Ethan



Will do, but I have no idea whether it will matter or not to treat the angled ceiling/wall where the speakers are (not the front wall). Would that have any benefit if I treated it like the front wall, if I deem it necessary.


Here's the pic again as a reminder:


----------



## Ethan Winer




> Quote:
> Originally Posted by *Stew4msu* /forum/post/0
> 
> 
> I have no idea whether it will matter or not to treat the angled ceiling/wall where the speakers are (not the front wall).



Yes, _all_ junctions are a great place for bass traps, even if the angle is not 90 degrees. Do it.










--Ethan


----------



## Stew4msu

Thanks Ethan, but I actually meant the entire angled wall (behind the speakers), as if it were an extension of the front wall.


I was already planning bass traps at the junctions.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Stew4msu* /forum/post/0
> 
> 
> I actually meant the entire angled wall (behind the speakers), as if it were an extension of the front wall.



I don't see the value unless your speakers happen to send sound that way making the angled part a reflection point.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Stew4msu* /forum/post/0
> 
> 
> Thanks Ethan, but I actually meant the entire angled wall (behind the speakers), as if it were an extension of the front wall.
> 
> 
> I was already planning bass traps at the junctions.



Well, I would treat it the area *just* behind the speakers. As the distance between them and the wall is essentially nil, an area perhaps only 3" beyond the footprint of the mounted speaker would do it. Sound does emanate from the rear of the speaker cabinet and this treatment will address that particular first reflection.


Just my $.02.


----------



## rutlian

Anybody ever use ATS ACCOUSTICS? service wise and feedback of their wall panels

seems that they have a good price.


----------



## bpape

If the speakers are relatively close to the wall, treating it is a good idea to minimize the impact of SBIR.


Bryan


----------



## dae3dae3

I was pricing materials to build my acoustic panels and found that the cotton batting that I was planning to put over the rock wool to prevent it from sending insulation dust into the room when the panels are handled is about four times the cost of the polyester batting. Is there any reason the polyester would not be suitable? It seems just as light and airy as the cotton.


----------



## dae3dae3

Geez, I've always suspected that I had the skills to kill a thread. I've never done it to a 2400+ post thread before though.


I don't know if I should be proud of myself or not.


----------



## eugovector

Poly batting should be fine. Go to Joann's, and buy some quilt padding. Thinner is better unless you're really going to be roughing up your panels.


----------



## BasementBob

dae3dae3:


I haven't subjected this to any ASTM C423 testing nor fire testing, but I can tell you it absorbs pretty good:
http://www.bobgolds.com/Absorber/home.htm 


The white stuff in the pictures is polyester batting I bought from wall-mart. I used it as a wrap.


----------



## dae3dae3

Thanks for the replies.


----------



## drunkpenguin

whats wrong with skipping the batting part? Is the fiberglass really going to float around the room if nobody is touching it?


----------



## eugovector




> Quote:
> Originally Posted by *drunkpenguin* /forum/post/0
> 
> 
> whats wrong with skipping the batting part? Is the fiberglass really going to float around the room if nobody is touching it?



Probably not, but for most people, it's a better safe than sorry approach. For me, I didn't have to worry about breathing the stuff, irritating my hands while cramming it into my frames if I wrapped it in poly first.


----------



## RobertR

I don't know if this question has been answered in this thread. The first post says use Linacoustic up to ear height (about 44 inches) for side walls. But what about risers? Is the same height maintained all the way to the back of the room? If so, "ear height" is no longer maintained for rows further back. For a 12 inch riser, there's only 32 inches of Linacoustic for the back row.


----------



## eugovector

Yep, if you have a riser, it would be a good idea to treat that area up to ear height.


----------



## BasementBob

RobertR:


The rough idea is to do the walls up to the point that the mirror reflection point is six inches lower than the top of the linacoustic. (The assumption is that imaging, over many seats, is more important than room reverb and spaciousness. You can go higher if you need to reduce room reverb further)


You can use that rough idea to determine how high to put the linacoustic on the walls, combined with knowing how high your mains tweaters are, and where your front row ears are, and where your riser row ears are.


If your mains tweaters are higher than your ears, then having the linacoustic just up to your ears is too short.


If your mains tweaters are the same height as your ears, then having the linacoustic up to your ears is too short, but six more inches would be fine.


If your mains tweaters are under your screen, then having the linacoustic up to your ears is just fine (unless your screen is really way up there).


----------



## RobertR

Thanks for the detailed response, Bob!


----------



## wgilpin

 Here's a site detailing how I built my DIY absorbers. 


Cheers,


----------



## BasementBob

wgilpin
Good jointery you have there .


----------



## pepar




> Quote:
> Originally Posted by *wgilpin* /forum/post/0
> 
> Here's a site detailing how I built my DIY absorbers.



Very nice, and nice website, too. Your mounting method spaces them away from the wall; was this intentional to get some beneficial acoustical effect, or just a by-product of the mounting method?


----------



## wgilpin




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Very nice, and nice website, too. Your mounting method spaces them away from the wall; was this intentional to get some beneficial acoustical effect, or just a by-product of the mounting method?



Thanks!


Spacing them away from the wall was intentional. I wanted to use both sides of the insulation to maximize their effectiveness. Plus, it looks kinda cool.


----------



## bpape

Nice looking wes. The Cherry and black is a nice combination.


Bryan


----------



## Fatawan

If one was to do a star ceiling using black velvet as the covering material on the ceiling, what would the acoustics effects be?


Thanks


----------



## McCall

It really depends on what velvet you are using here. I use stretch velvet in my theater it is over my speakers and does not affect them any more than speaker cloth did. I also have it over my acoustic all treatments.

A solid velvet, non stretch, may absorb more but the stretch one, WHEN STRETCHED if pretty transparent.


----------



## Stereodude

I read through the entire thread and have a question that wasn't exactly answered. I understand a bass trap can be nearly any size shape, but both obviously of those dictate effectiveness... Most bass traps get placed into a corner at a 45 degree angle. What is the impact if the bass trap isn't at a 45 degree angle?


For example, how would these (see attachment) bass traps work? They are in the corners of the walls and ceiling. Would they be only marginally effective? What could be done to improve them without having them extend down more than 1 foot from the ceiling?


----------



## bpape

They'll still work - they just won't have the hump in absorbtion nor extend as deep (depending on thickness) as the same thing stradding the corner. The difference is the distance from the leading edge of the absorbtion to the boundary behind.


Bryan


----------



## Stereodude




> Quote:
> Originally Posted by *bpape* /forum/post/0
> 
> 
> They'll still work - they just won't have the hump in absorption nor extend as deep (depending on thickness) as the same thing straddling the corner. The difference is the distance from the leading edge of the absorption to the boundary behind.
> 
> 
> Bryan



So, does 4" of 705 8" from the wall have nearly the same effect as 8" of 705" 4" from the wall? Also, at what point does the thickness of the material hit the point of diminishing returns, or is that material dependent? Is there a rule of thumb for surface area on bass traps? Like less than 4 square ft of surface don't bother?


----------



## bpape

Generally, the max 'extra benefit' IMO is an airspace equal to the thickness of the absorbtion. So, 4" gap behind 4" of material. More than that, and it can actually begin to be more like a filter and introduce a different peak in absorbtion.


Also, once you start getting thicker, you can save some money and use 703 instead of 705. How thick you go depends on how deep you need to go. More is better to a point. As far as surface area, it's really more a function of what else is going on in the room and how large the room is (proportion of control to room volume). 4 sq ft in a 3x3x8 closet is absolutely worth doing. In a 15x20x8 room, it certainly won't hurt but don't expect miracles.


Bryan


----------



## Deathwish238

Moved...


----------



## techshare31

Hopefully, the pictures say it all. I'm just looking for some ideas on how I can make this kind of undefined room sound better. You'll notice on the rear of the room I've got three windows. I'm planning on addding some heavy curtains to those windows anyway ... however I'm not sure how much benefit that will give me in the way of acoustics as it's only the rear wall.


The room has no right wall with just a half "bar" type wall which joins into the kitches as you can see. On the left there is a wall which opens on the front left corner to a rather large opening to the next room and hallway. I believe the room is roughly 15X18ft with "vaulted" ceilings that go from 8-10ft. Thanks for any ideas and as always I'm looking for the most bang for the buck. I'm not opposed to the pre-fab acoustic stuff, but I think I'll need to try something I can experiment with do to the odd shape and setup of this room.


----------



## techshare31




> Quote:
> Originally Posted by *techshare31* /forum/post/0
> 
> 
> Hopefully, the pictures say it all. I'm just looking for some ideas on how I can make this kind of undefined room sound better. You'll notice on the rear of the room I've got three windows. I'm planning on addding some heavy curtains to those windows anyway ... however I'm not sure how much benefit that will give me in the way of acoustics as it's only the rear wall.
> 
> 
> The room has no right wall with just a half "bar" type wall which joins into the kitches as you can see. On the left there is a wall which opens on the front left corner to a rather large opening to the next room and hallway. I believe the room is roughly 15X18ft with "vaulted" ceilings that go from 8-10ft. Thanks for any ideas and as always I'm looking for the most bang for the buck. I'm not opposed to the pre-fab acoustic stuff, but I think I'll need to try something I can experiment with do to the odd shape and setup of this room.



Well! No replies yet but as an update I went out and got some fairly heave suede type drapes. They aren't even pressed yet but I got 'em up there and played some movie sound. I am now a believer in room treatment. Just those drapes on the rear window seemed to improve the sound. I was able to hear more surround and the clarity at higher volume was better. For lack of a better word, there seems to be less "racket" between the sound I want to hear.


Now what to do next ....


----------



## jeppe

hi,whats up with them stacked triangle corner traps floor to ceeling in each corner of the room? sounds like a great idea

whats the imortant notes on the size, density&windfloow of the mineralwool ?

im from europe and sorry too say it seems that i cant find any Owens corning over here...

just isover,paroc and knauf insulations.


----------



## Jason Jones




> Quote:
> Originally Posted by *jeppe* /forum/post/0
> 
> 
> hi,whats up with them stacked triangle corner traps floor to ceeling in each corner of the room? sounds like a great idea
> 
> whats the imortant notes on the size, density&windfloow of the mineralwool ?
> 
> im from europe and sorry too say it seems that i cant find any Owens corning over here...
> 
> just isover,paroc and knauf insulations.



These are usually made 2 feet (61 cm) wide and with material that is 3-6 pcf (48-96 kg/m^3).


Jason


----------



## BasementBob

jeppe:


What you're talking about is called a Studiotips SuperChunk .

http://www.bobgolds.com/TrapHarder/home.htm 


The largest that I know of anyone making diagonal corner Studiotips SuperChunks is this
http://www.bobgolds.com/CornerTrapCut.GIF 


You can use anything on this page: http://www.bobgolds.com/AbsorptionCoefficients.htm 

In your case perhaps RW3 or RWA45 is what you want. I think there's a store called "Travis Perkins" that sells the stuff.
http://www.bobgolds.com/InsulationContractors.htm might have an address near the bottom.



Generally speaking, the bigger you make them, the less dense you want to fill it with, but not so loose that it falls over.


----------



## jeppe

hi thanks for them very nice links man









so more absorption volyme on the tringle superchunks than a simple 4"board against the corner right...does it have any negative effects when the triangle are right against the wall whith no air behind?


----------



## BasementBob

jeppe



> Quote:
> so more absorption volume on the tringle superchunks than a simple 4"board against the corner right



Yes, a Studiotips SuperChunk uses a lot more material to get a slighly more even broadband absorber than just a simple 4" board placed diagonally across the corner.



> Quote:
> does it have any negative effects when the triangle are right against the wall whith no air behind?



No. For any single diagonal size, filling the space right to the wall is believed to be optimum. For any single triangle cut size, it's possible to pull them out from the wall and that might or might not be better acoustically/absoratively, but I'd think it would fall over to make a in-the-room-pillar like that without wall support.


----------



## jeppe









man thats great too hear,so now i try too find me some nice 4" rockwool or something like that and start cutting hallelulia, i must match my room acoustics with my 15" sub... some modal ringing there...


----------



## bpape

Just for completeness, if you're going to do the chunks (which work very well), the amount of material is exactly the same as straddling the corner with 6" of thickess (assuming a 2' face) and will use less space in the room.


Each 2'x4' piece will cut into 8 pcs that are 17x17x24". So, a 2" thick 2'x4' piece will give you a solid triangular chunk that is 17x17x24 and 16" tall. For an 8' ceiling, you'll need 6 pcs - same as 2'x4'x6" straddling the corner on top of each other.



Bryan


----------



## QueueCumber

I'm constructing some panels and was curious about using 3M 77 Spray adhesive to attach the GoM fabric. What is the best way to do this so that it won't affect the acoustic properties of the 2" OC 703? Can I spray it on the front face of the OC703 and the fabric that will be on the front of the OC703 to bond them together, or will this seal them and make the OC703 useless underneath? What do people recommend?


Also, if anyone has worked with Rotofast Snap-ins before and had to remove treatments from them, does anyone have a method that will work without destroying the absorption panel?


Thanks.


----------



## BasementBob

QueueCumber:


The usual recommendation is to wrap the 703 like a christmas present, spraying the 3M 77 only on the back.


If you use 3M 77, do it outside -- when it sprays it puts glue on everything in the room.


----------



## jeppe









hello again thanks for that idea...

but maybe a little bit to small for me?

my rectangular room is; 1579^3

16.1'

12,0'

8,2'




first length specific roomresonance is @35hz.rigth?


i think i would need some bigger triangels than that no?

i was aiming to cut 3 pieces of one 2'wide 4'long piece

each triangle to measure= 33*33*47"

now thats something for my ugly standing wawe @70hz on my wall behind my chair where i am seated right?

now thats pretty big too have 4 of them the same size in my thiny little living room (i would like to have a place where i can have my sofa!) so i was thinking what about only putting one 12 feet tall @ the ceiling/wall corner angle horizontally....

now seriosly what do you think about it? is this a good idea or is there something better that comes too your mind? it is doable...


(sorry i am not so good on english)

/cheers jeppe


----------



## Petrucci

I am about to treat the front wall of my theater with linacoustic duct liner. I am only gong to need about 90sq foot of duct liner to do the front wall so I will have alot of linacoustic left over. I was considering using the leftover linacoustic to build corner traps. Do you folks think it would be effective to cut the duct liner to about an 8ft length and then just roll it up like a poster to stand 8ft vertically and then fasten it to the corners with some kind of adhesive??


----------



## eugovector

How thick/Wide is the linacoustic?


----------



## Petrucci




> Quote:
> Originally Posted by *eugovector* /forum/post/0
> 
> 
> How thick/Wide is the linacoustic?



I havnt purchased the roll yet but the local HVAC supplier in my area sells rolls that are 1" thick and 48" wide. I think the smallest roll would be 200 linear feet.


Eric


----------



## eugovector

I think you'd be better off building a panel to straddle the corner, 6" thick or so. Or cut it up super chunk style. I just don't think that rolling 48" is going to give you enough mass, but someone here may correct me.


It's more work, but I think it will be more effective and look better when it's done.


----------



## nathan_h

I'm building a dedicated room inside my detached garage.


Main thread: http://www.avsforum.com/avs-vb/showthread.php?t=782601 


Without filling this thread with posts copied from my main thread and the specific topic on what size to build the room-within-the-garage -- or whether to just Green Glue more drywall to the existing drywall -- I'll reference the thread and just include some of the details, here.


Here are the details of what I'm struggling with now: http://www.avsforum.com/avs-vb/showt...8#post11233278 


-----



> Quote:
> Now it's time to make some dimension and construction decisions. From what I can estimate, the cost different between putting a second layer of drywall over the existing drywall (using the case of Green Glue a gracious fellow AVS-er set me up with) is less expensive than building four new interior walls... though I will have to build one new interior wall, anyway, to break up the room.
> 
> 
> But I'm thinking it may be worth it to essentially build a room within the garage, that is almost as wide, and similarly as tall, as the current space -- because it lets me choose a more optimum size for acoustics, and the air gap between the false room on the slab, the walls of the actual garage, perhaps 6 to 12 inches, will help contain sound within the space AND prevent sound from leaking in.
> 
> 
> And building a 2x4 frame for four walls to enclose a space of approx 13' x 16' is not astronomically more than doing a single wall....
> 
> 
> But it raises the question of the RIGHT dimensions.
> 
> 
> I've re-oriented the room to have the screen on the long wall -- so the room is wider than deep. I've got it figured out to have the seating at 2/3 of the way back from the screen. And, of course, the sweet spot seat will be centered on the screen and equidistant from each side wall.
> 
> 
> Plugging all this into the calculators tells me:
> 
> 
> 13 x 17 x 7 room (17 is the max width, and 7 is the max ceiling with out having some cross beams visible): I've got single peaks at 66,161, and 199 hz. Double peaks at 132 and 256 hz. And single nulls at 33, 80,100, 166, and 299 hz. And a double null at 242 hz. AND 5 problem frequencies: 132, 166, 173, 241, 256.
> 
> 
> NOT SO GOOD!
> 
> 
> But, if I do 12.5 x 16 x 7.33, I get no peaks and no nulls! Of course, there are still 4 problematic frequencies, according to the calculator: 141, 180, 230, and 282 hz.
> 
> 
> Other options can reduce the "problem frequencies" to just two, BUT then introduces two peaks. 13 x 16 x 7.33 is an example.



Calculators are attached:

http://www.avsforum.com/avs-vb/attac...chmentid=86462 



> Quote:
> The best bet according to the experts appears to be to remove the drywall on the existing wall and increase the cavity between that and a new wall I build.
> 
> 
> BUT: The existing walls are insulated, which is nice. That's one reason I hesitate to pull the drywall off and create a VERY WIDE cavity between the garage exterior and the new "wall" inside the garage: I'll lose that insulation. I also REALLY like the idea that this theater could be an isolated room within the garage -- only really touching the garage in that it sits on the same concrete slab.
> 
> 
> Plus, one day if we reconstruct the theater, we'll be left with a garage without drywall and insulation (which I realize is not that unusual but still).
> 
> 
> Budget is always of concern BUT I already have a case of Green Glue. And if doing it "right" (or better) costs a bit more, and that becomes a budget issue, I'll just push out my timeline a bit. Luckily, I can watch movies in the living room for now. It's far from ideal, but it works.
> 
> 
> What I don't want to do is save $1k in materials and end up with something far less workable (sound bad inside and sound leaks more outside) because I was cheap/impatient.



And the layout:

http://www.avsforum.com/avs-vb/attac...chmentid=86552 


Note that the entrance to the garage is at the bottom of the picture and is cut off. Right now, the garage is empty, so I have a blank slate.


Another idea is to use non-parallel walls -- which is intriguing to me. I guess that would be good -- but it's not clear to me whether that helps only with problem frequencies related to combing, modes/peaks/nulls, and/or? And then, would I want to maximize my square footage and stop trying to build to "ideal dimensions"?


----------



## Deathwish238

What's the best acoustical material to buy on a budget? I assume there'ld be a best for bass traps and another for normal panels


----------



## jeppe

well arent you a lucky guy to live in US i have a hell of a problem finding me some decent wool over here in europe check out this man it seems pretty nice to me!


RHT 40 Industrial Board


some really nice absorptioncoefficents numbers in the pdf-file on the roxull homepage...


----------



## nathan_h




> Quote:
> Originally Posted by *Deathwish238* /forum/post/0
> 
> 
> What's the best acoustical material to buy on a budget? I assume there'ld be a best for bass traps and another for normal panels



For bass traps, try doubling or tripling up 2" thick boards of Owens Corning 703 brand 3 lbs. per cubic foot density semi-rigid fiberglass board -- 48"x24"x2" Panels at about $15 each. Of course, you'll want to cover them up, which adds to the cost, and you'll need to pay for shipping, since it's only sold to contractors and not directly to consumers.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> For bass traps, try doubling or tripling up 2" thick boards of Owens Corning 703 brand 3 lbs. per cubic foot density semi-rigid fiberglass board -- 48"x24"x2" Panels at about $15 each. Of course, you'll want to cover them up, which adds to the cost, and you'll need to pay for shipping, since it's only sold to contractors and not directly to consumers.



Not completely true. Specialty Products & Insulation Co. (SPI) sells to end-users and at very favorable prices - IMO - as well. They have branches all over the U.S. Of course, they will not sell individual sheets, but most home theater projects (can) use bulk.


----------



## jeppe

speciality products&insulation co.

is a buisness partner with Roxul, maybe they have the rth-40 industrialboard


the absorption numbers for 4" are; 1.07 1.01 1.07 1.06 1.07 1.06 1.05

isnt that better values than owens corning 703?


wonder how many dollars they would quote me for one pallete to europe hmm... probably over 1000$


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Not completely true. Specialty Products & Insulation Co. (SPI) sells to end-users and at very favorable prices - IMO - as well. They have branches all over the U.S. Of course, they will not sell individual sheets, but most home theater projects (can) use bulk.



Thanks for the tip about other suppliers. Very good to know.


----------



## jeppe

if you like to go with thicker like 6"

here another tipp for you..


owens corning 1240


absorption numbers; 1.32 1.14 1.11 1.09 1.06 1.07 1.10 thats some nice numbers allright...


----------



## lavarenne

This approach has worked for me on the basis of having the wall behind the front speakers needing replastering - therefore the acoustic high density foam approach with overlaying quilt wadding and a final layer of suede efffect material seemed much cheaper and more appealing (I am no plasterer). Furthermore the rear wall is divided by a large double french door with a thick velvet curtain across, so there didn't seem much point in any further treatements. There is also a small diagonal wall (where the chinmey was once in the corner next to the front wall) which has the same treatment as the rest of the front wall. Overall the room is adequately assymetrical and sounds dead without deadening the AV sound. Thick curtains, a sofa complete the sound absorbtions as well as the door having the same treatment as the front wall. Bass has not been a problem as the sub is kept under check and the main fronts with their transmission line construction handle bass in the lower ocatves quite well. It was not scientific in its approach but more driven by decorative requirements and circumstance. However, the soft wall behind the screen also does a good job of mopping up stray light reflection as well.


----------



## nathan_h




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> I'm building a dedicated room inside my detached garage.
> 
> 
> Main thread: http://www.avsforum.com/avs-vb/showthread.php?t=782601
> 
> 
> Without filling this thread with posts copied from my main thread and the specific topic on what size to build the room-within-the-garage -- or whether to just Green Glue more drywall to the existing drywall -- I'll reference the thread and just include some of the details, here.
> 
> 
> Here are the details of what I'm struggling with now: http://www.avsforum.com/avs-vb/showt...8#post11233278
> 
> 
> -----
> 
> 
> 
> 
> Calculators are attached:
> 
> http://www.avsforum.com/avs-vb/attac...chmentid=86462
> 
> 
> 
> 
> And the layout:
> 
> http://www.avsforum.com/avs-vb/attac...chmentid=86552
> 
> 
> Note that the entrance to the garage is at the bottom of the picture and is cut off. Right now, the garage is empty, so I have a blank slate.
> 
> 
> Another idea is to use non-parallel walls -- which is intriguing to me. I guess that would be good -- but it's not clear to me whether that helps only with problem frequencies related to combing, modes/peaks/nulls, and/or? And then, would I want to maximize my square footage and stop trying to build to "ideal dimensions"?



To follow on to these questions, my most recent thought has been since I can construct anything within the outer limits of the existing garage, I could do something asymmetrical -- like a modest trapezoid and/or with something like chevrons along the sides.


----------



## haslip

I am looking for outside the box acoustic treatment looks, and thus have a question.


I can put two pieces of Owens Corning 703 behind this 53" x 53" tapestry. I have black walls, and I was just going to put black around the edges of the 703 and put this over top? Could it work?











This finely crafted wall tapestry is made in the USA by skilled artisans, using Jacquard looms and pure cotton yarn. An iron rod and finial are included, in addition to brackets and hardware for easy hanging.


----------



## Ethan Winer

Yes, that'll be great, as long as the tapestry is reasonably "soft" and absorbent.


--Ethan


----------



## GB_KSU

I have a couple of questions for the experts:


First off, this past winter I did some DIY treatment to my room, consisting of front corner treatment and an angled soffit using 703 in a super wedge fashion. (I believe that is what it is called). The only difference is that I used 1' wedges vs. 2'. I also hung some 2x4 panels for first reflection points on the side walls. To my ear the room improved a good deal. However I am looking to rework the room as I am unhappy with how the fabric coverings turned out. When I do this I will essentially be removing all of the treatment. I only took simple measurements of the room with an spl meter before adding the treatments. With that said I would really like to take some good base measurements of the room minus treatment before I finalize another plan. I have been looking at the software and equipment on the Rives site and was curious as to what the opinions are regarding these programs. Is it worthwhile to invest in one of the test kits? I will say that I am young, and this is my first home so it certainly won't be the last room I ever work in.


I also noticed a room on the Audiogon forums that I found very attractive. The owner had some very unique absorption panels installed. Here is a link to a site documenting the build:
http://www.zerogain.com/forum/showthread.php?t=15669 

I love the look of these panels, but I don't quite understand how they "work". I am assuming that the size and spacing of the openings in both the "top" panel and mdf panel would make them more efficient at certain frequencies? I would think that they would be highly reflective for the most part? Please enlighten me!


----------



## Mike N Ike

I have a less than ideal room, 19' x 16', carpeted , drapes, sofa, loveseat and one wall of bookcases. I think my biggest issue is the cathedral ceiling. Starts at about 10' and is 18' high. At at the high point it opens into a loft area. Lots of cubic ft.! Room seems to have a certain amount of echo/reverb. I was considering absorption panels at the side 1st reflection points and the back wall. Possibly in the front below the screen also. If it matters, the screen is along the 19' wall and the ceiling rises frm left to right when facing the screen.


Will acoustic treatments be a bit of wasted effort given the ceiling? Anyone have any suggestions?


Thanks,

Mike


----------



## BasementBob

GB_KSU:


What you're looking at is a slot absorber, a variation of the Helmholtz resonator.


It tends to resonate at a single frequency (sort of a bell curve with a single peak), depending on the ratio of slot width to surface area, depth of the cavity, and amount of absorption within the cavity.


This page will give you some of the ideas, but unfortunately some of the formulas are wrong
http://www.mhsoft.nl/helmholtzabsorber.asp 


The correct formula can be found here
http://forum.studiotips.com/viewtopic.php?t=94 


In practice, getting these things to resonate/absorb at the desired frequency is hard, as is keeping them from ringing (also bad). Ringing is when the panel continues to vibrate at that frequency, emitting sound, after the speaker has stopped producing it.


----------



## nathan_h




> Quote:
> Originally Posted by *Mike N Ike* /forum/post/0
> 
> 
> I have a less than ideal room, 19' x 16', carpeted , drapes, sofa, loveseat and one wall of bookcases. I think my biggest issue is the cathedral ceiling. Starts at about 10' and is 18' high. At at the high point it opens into a loft area. Lots of cubic ft.! Room seems to have a certain amount of echo/reverb. I was considering absorption panels at the side 1st reflection points and the back wall. Possibly in the front below the screen also. If it matters, the screen is along the 19' wall and the ceiling rises frm left to right when facing the screen.
> 
> 
> Will acoustic treatments be a bit of wasted effort given the ceiling? Anyone have any suggestions?
> 
> 
> Thanks,
> 
> Mike



Nope, not wasted effort -- and starting with first reflection points (walls, floors, ceilings) is a good place to start.


----------



## nathan_h




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> I'm building a dedicated room inside my detached garage.
> 
> 
> Main thread: http://www.avsforum.com/avs-vb/showthread.php?t=782601
> 
> 
> Without filling this thread with posts copied from my main thread and the specific topic on what size to build the room-within-the-garage -- or whether to just Green Glue more drywall to the existing drywall -- I'll reference the thread and just include some of the details, here.
> 
> 
> Here are the details of what I'm struggling with now: http://www.avsforum.com/avs-vb/showt...8#post11233278
> 
> 
> -----
> 
> 
> 
> 
> Calculators are attached:
> 
> http://www.avsforum.com/avs-vb/attac...chmentid=86462
> 
> 
> 
> 
> And the layout:
> 
> http://www.avsforum.com/avs-vb/attac...chmentid=86552
> 
> 
> Note that the entrance to the garage is at the bottom of the picture and is cut off. Right now, the garage is empty, so I have a blank slate.
> 
> 
> Another idea is to use non-parallel walls -- which is intriguing to me. I guess that would be good -- but it's not clear to me whether that helps only with problem frequencies related to combing, modes/peaks/nulls, and/or? And then, would I want to maximize my square footage and stop trying to build to "ideal dimensions"?



I may not have made it clear what I meant by non-parallel walls. I mean something like this, since I can modify the interior dimension:











or even this, though I couldn't really do a ceiling like that, as the photos of my room indicate:


----------



## GB_KSU




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> GB_KSU:
> 
> 
> What you're looking at is a slot absorber, a variation of the Helmholtz resonator.
> 
> 
> It tends to resonate at a single frequency (sort of a bell curve with a single peak), depending on the ratio of slot width to surface area, depth of the cavity, and amount of absorption within the cavity.
> 
> 
> This page will give you some of the ideas, but unfortunately some of the formulas are wrong
> http://www.mhsoft.nl/helmholtzabsorber.asp
> 
> 
> The correct formula can be found here
> http://forum.studiotips.com/viewtopic.php?t=94
> 
> 
> In practice, getting these things to resonate/absorb at the desired frequency is hard, as is keeping them from ringing (also bad). Ringing is when the panel continues to vibrate at that frequency, emitting sound, after the speaker has stopped producing it.




Thanks for the links Bob I appreciate it. I was considering making just the faces of the corner treatments and soffits similar to this but it sounds like it would be a bad idea. Am I correct to assume that any sort of wood panel, slotted or not will resonate at a given frequency?


Any input at all on the software? I don't own a PARC, so the BARE software seems unnecessary? Would ETF with a quality mic setup give me enough information to make good choices for treatment options?


----------



## Ethan Winer




> Quote:
> Originally Posted by *GB_KSU* /forum/post/0
> 
> 
> Would ETF with a quality mic setup give me enough information to make good choices for treatment options?



Yes, and you don't even need a "quality mic" since even the cheap ones are fine at bass frequencies - below 300 Hz is where all the action is.


--Ethan


----------



## GB_KSU




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> Yes, and you don't even need a "quality mic" since even the cheap ones are fine at bass frequencies - below 300 Hz is where all the action is.
> 
> 
> --Ethan




Thanks for the advice Ethan. I know that a Radio Shack spl meter can be used with the ETF software, would I gain anything by using a mic? I assume that using a mic would allow for the data to be automatically inputted? If so do you have suggestions for something that would be adequate?


----------



## monkeychucker

I have a question about bass trap construction. I am using 1" linacoustic to treat first reflections and the front of the theater. I will likely have a fair amount left over and am wondering if I can some how use the remainder to build some base traps? Also, for decorative purposes we are creating faux columns using 10" cardboard tubes used for concrete. If I packed some sort of material inside such as compressed regular fibreglass insulation or even paper would this create an effective trap?


Thanks,

Dwayne


----------



## pepar




> Quote:
> Originally Posted by *monkeychucker* /forum/post/0
> 
> 
> . . . for decorative purposes we are creating faux columns using 10" cardboard tubes used for concrete. If I packed some sort of material inside such as compressed regular fibreglass insulation or even paper would this create an effective trap?
> 
> 
> Thanks,
> 
> Dwayne



Only if the sonotubes are acoustically transparent at bass frequencies. (I'm sure that they are not.)


----------



## Ethan Winer




> Quote:
> Originally Posted by *GB_KSU* /forum/post/0
> 
> 
> Thanks for the advice Ethan. I know that a Radio Shack spl meter can be used with the ETF software, would I gain anything by using a mic?



A Radio Shack SPL meter _is_ a microphone, and it also has a preamp which makes it easier to connect to consumer-grade sound cards through their line input. The next step up in microphones probably costs more than you want to spend, and won't be appreciably better for "home" use anyway.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *monkeychucker* /forum/post/0
> 
> 
> wondering if I can some how use the remainder to build some base traps?



If you stack four pieces adjacent to be four inches thick you can use them as corner traps as explained in my Acoustics FAQ:

http://www.ethanwiner.com/acoustics.html 


--Ethan


----------



## jeppe











Todays scope;


Here are the Most important site for you northern americanos...

that are on the hunting for some nice insulation products check it out

it list EVERY insulation plant in north amerika from mexico up to canada...


also links to every insulation manufactor.and much more...

www.naima.org 

http://www.naima.org/pages/about/members/map.html 





-------------------------------------------------------------------------------------------------------

AND for mechanical&special insulation products only...


http://www.insulation.org/about/


----------



## nathan_h

That's funny! Actually, I can see an Owens Corning facility when driving to and from work, but trying to find a place that will sell their quietzone products or the rigid insulation that is ideal for bass traps, locally in person, is almost impossible.


----------



## jeppe











Todays scope number 2;


Here are the Most important site for us european folks thats on the hunt for some nice insulation...

the European eqivalent from spain to russia...even turkey

www.eima.org 

http://www.eurima.org/our_members.cfm 




--------------------------------------------------------------------------------------------------------


AND for mechanical&special insulation products only...


http://www.insulation.org/links/fesi.cfm 


whith memberlinks for many countries all over europe...

now aint that something!!!


----------



## jeppe











i dont know if there are any japaneese folks reading this forum but anyway...

http://www.glass-fiber.net/ 




australian folks...look at; www.farima.net 


Fibreglass and Rockwool Insulation Manufacturers Association of Australia (FARIMA)

under construction for now...


----------



## jeppe




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> That's funny! Actually, I can see an Owens Corning facility when driving to and from work, but trying to find a place that will sell their quietzone products or the rigid insulation that is ideal for bass traps, locally in person, is almost impossible.



have you tried to e-mail them

or; [email protected] (Western Insulation Contractors Association) ?

http://www.insulation.org/links/regional.cfm#8 


seems vierd if they dont have some information...


naima.org for regular home insulation products

insulation.org for special insulation (like industrial ventilations etc.. i think...)


----------



## nathan_h

I'm sure I'll be able to find a place to sell me what I want, but Owens Corning's customer support said, essentially, that they are not consumer products so I won't be able to buy them.


----------



## jeppe

man that sucks!


i talk to owens corning here in europe and they said something similar to me too

one container or more! , they dont distubute smaller to europe...

any nice ideas on Certain tead wool?

i read its a part of the giant

Saint gobain/Isover.

europes biggest manufactor of rigid fiberglass...


----------



## haslip

I am framing 2inch Owens Corning in 1x3s and placing them on my walls with a little spacing.


I wrapped them first in batting material which is very porous, but I wonder if I choose wisely for the black fabric covering and need help.


For some reason, I thought that a natural material, like wool or cotton was superior to a man-made like polyester, but now I see a major manufacturer of wraps uses man-made, so I don't know if that is correct.


I choose 100% cotton, and my question is, is the weave to tight. If I put it up to light, i can see some filter through, but the blow through test is where it may fail.


I can blow through it, and breath in through it, but it takes effort. Do I need to rethink my material choice??


Scott


----------



## nathan_h

While I haven't resolved my room dimensions issue noted above, yet -- it's nice to be able to create a room of "any" size, but it's tough deciding what size is best because though the calculators are awesome it's hard to decide which peaks and which nulls and which problem frequencies matter most -- I'm working on other angles as well.


Today's question:


I've got REAL bass traps (thanks, Ethan), auralex foam, and a desire to add diffusion to the mix. Remember, this is a dedicated, custom built room and I won't have anything like shelving in there.


I've seen lots of info about building one's own bass traps, and one's own absorption panels. But I've not seen any DIY info about building diffusion panels. Can anyone point me in that direction?


----------



## Scott R. Foster

DIY diffusers... scroll down

http://forum.studiotips.com/viewtopic.php?t=48 


For ratio exploration err to the side of larger room volume.


A comprehensive tool for looking at the modal structure of a proposed room

http://www.bobgolds.com/Mode/RoomModes.htm 


Some very neat charts that map the phase space of "good" ratios

http://forum.studiotips.com/viewtopi...r=asc&start=40 


Good Luck!


PS: try these guys for mineral fiber

http://www.spi-co.com/servicecenterdirectory.html


----------



## nathan_h

Thanks. That's a great calculator. It doesn't take into account seating position, and speaker position, which some do -- but it's a really quick easy way to see what dimensions are doing -- and then once I find a good dimension, I can go to the more complicated calculator and worry about speaker and seating location.


The thread about homemade diffusers was interesting. Not sure how ambitious I am yet but the idea of using curved surfaces is very interesting. I was wandering around Lowes looking for stuff that I could adapt into one of a panel of many different height surfaces and didn't find anything. The idea of using curved items is appealing.


(I was going to buy a bunch of 2 inch PVC pipe, and cut pieces of random lengths between one inch and three inches, and then clue them perpendicular onto a board.... When on the wall, it would look like you're flying above a city full of round buildings with not roofs. But now I'll keep thinking about ideas.)


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> I've not seen any DIY info about building diffusion panels. Can anyone point me in that direction?



See this:

http://www.mhsoft.nl/user/acoustic%20calculator.asp 


--Ethan


----------



## nathan_h

That looks very promising. I submitted me email address and will hopefully get the download link, soon. Thanks.


----------



## drunkpenguin




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> 
> (I was going to buy a bunch of 2 inch PVC pipe, and cut pieces of random lengths between one inch and three inches, and then clue them perpendicular onto a board.... When on the wall, it would look like you're flying above a city full of round buildings with not roofs. But now I'll keep thinking about ideas.)




depending on how you do it, it could look like the death star in star wars! that would be neato.


----------



## Jason Jones




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> (I was going to buy a bunch of 2 inch PVC pipe, and cut pieces of random lengths between one inch and three inches, and then clue them perpendicular onto a board.... When on the wall, it would look like you're flying above a city full of round buildings with not roofs. But now I'll keep thinking about ideas.)



For the diffuser design to work as intended, your buildings will need roofs.










Jason


----------



## nathan_h

! That's funny, but after looking around a bit more, I see what you mean.


I'm actually thinking that buying a batch of 2x2 boards, and cutting them into pieces of predetermined lengths, might be easier and look better.


But I think that once I get access to the software on the mentioned site:

http://www.mhsoft.nl/user/acoustic%20calculator.asp 


I'll have more detailed understanding. Trouble is, one has to wait for that site owner to send one the link, and that person hasn't responded to my emails, yet


----------



## Jason Jones




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> ! That's funny, but after looking around a bit more, I see what you mean.
> 
> 
> I'm actually thinking that buying a batch of 2x2 boards, and cutting them into pieces of predetermined lengths, might be easier and look better.
> 
> 
> But I think that once I get access to the software on the mentioned site:
> 
> http://www.mhsoft.nl/user/acoustic%20calculator.asp
> 
> 
> I'll have more detailed understanding. Trouble is, one has to wait for that site owner to send one the link, and that person hasn't responded to my emails, yet



Are you planning on doing the "Skyline-type" or the "well-type" diffuser? If you want, I'll show you how to figure the lengths.


Jason


----------



## nathan_h

I'm thinking the skyline type is easier to create (with my limited skills). If there's a handy way to figure for a given number of "buildings" what the relative heights should be, etc., I would love to be pointed to that information. Thanks!


----------



## eugovector




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> I'm actually thinking that buying a batch of 2x2 boards, and cutting them into pieces of predetermined lengths, might be easier and look better.
> 
> (



I think the problem with this approach when building a skyline style is that it will weigh a ton.


----------



## Jason Jones




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> I'm thinking the skyline type is easier to create (with my limited skills). If there's a handy way to figure for a given number of "buildings" what the relative heights should be, etc., I would love to be pointed to that information. Thanks!



Use this map: http://www.mhsoft.nl/DiffusorCalculator.html 


You then need to pick a depth for your longest "building"







. Six or seven inches is about ideal for this plan. Now convert your map into inches. So, where you have a 1 on the map your "building" will be 1/4*6", where you have a 2 it will be 2/4*6", etc.


After the heights are figured then you need to decide the size of board (or whatever) to use. Here 2" by 2" is a good size. This will give you a 24" x 24" panel.


Yes, it will be really, really heavy. Good luck!


Jason


----------



## nathan_h

Very cool. Now I gotta figure out the weight thing.... I wonder if Home Depot carries balsa wood?


----------



## tonybradley




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/10803652
> 
> 
> I wouldn't be so quick to have Tony go to all that trouble. Maybe some felt reflects, but the stuff I've seen does not.
> 
> 
> Tony, try this simple test: Stand in front of one of your panels and "talk into" it. Does it sound like you're talking into a total void? If so, then the felt is probably fine. If you still have some raw fiberglass, use that as a comparison. If they both sound the same, then the felt is fine. If you hear more of your voice coming back on the panel with felt, then you must have bought some of that "reflective felt" Terry is referring to.
> 
> 
> --Ethan



Sorry to bring this up again, but I need some more answers. I was surfing the web trying to find some Acoustically Transparent Fabric that was not $15-$20 a yard like GOM. I then remembered I had some left over MUSLIN and FELT.


I did the 'blow' test and blew through both fabrics. I felt much more air when blowing through the FELT than I did when I blew through the MUSLIN. Some said Felt would reflect at frequencies higher than 4khz. My question is this: Since I've determined that I can blow more air through my Felt than my Muslin, and Muslin is acceptable to cover Fiberglass at the 1st reflection points, can one assume the Felt I have (based on the air test) will work as well as the Muslin?


----------



## HeyNow^

Tony,


You may want to try Dazian. I am going to use the Janus and Black Celtic cloth. Good color selection and 701 IFR rated.


----------



## tonybradley




> Quote:
> Originally Posted by *HeyNow^* /forum/post/11406701
> 
> 
> Tony,
> 
> 
> You may want to try Dazian. I am going to use the Janus and Black Celtic cloth. Good color selection and 701 IFR rated.



Where can you purchase Dazian fabric? I'd like to check out the prices and colors.


----------



## HeyNow^

Dazian.com


----------



## Ethan Winer

Tony,



> Quote:
> Originally Posted by *tonybradley* /forum/post/11402339
> 
> 
> can one assume the Felt I have (based on the air test) will work as well as the Muslin?



You may be over-thinking this. Felt is fine. Really.










--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11410457
> 
> 
> Felt is fine. Really.



Didn't we touch on this recently and wasn't the takeaway that there are several kinds of "felt" and some would be fine while others wouldn't?


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/11410496
> 
> 
> Didn't we touch on this recently and wasn't the takeaway that there are several kinds of "felt" and some would be fine while others wouldn't?



Okay, I'll clarify - normal felt from a normal fabric store is fine. You know, like the kind he said he tested and was able to blow through easily.










--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11410572
> 
> 
> Okay, I'll clarify - normal felt from a normal fabric store is fine. You know, like the kind he said he tested and was able to blow through easily.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan










I knew there was something that I missed.


----------



## Petrucci

What are your thoughts about treating the area of wall directly to the left and right of the viewing positon? I have already treated the front wall with 1" linacoustic and 4" oc 703 traps on the corners. I also have all of the first reflection points covered with 2" oc703 and things sound pretty good at this point. I do however have some extra 2" panels and didnt know if I should just stop where I am at or treat that area to the left and right of the viewer.


Any thoughts?


Thanks,

Eric


----------



## jchretien4

Time to put in ceiling in a small (12' x 20') theater in basement. 8' ceiling, with 12" space between joists filled with pink insulation.


I think the drop ceiling would be easier, but the drywall ceiling better for acoustics. Any thoughts?


Drywall, I know, will be more difficult to put up, and there are potential future problems if I need access to pipes, wiring, etc. But as far as noise-dampening for the rooms above, isn't drywall better?


jchretien4


----------



## Scott R. Foster

Some folks do both... lay squares of drywall on top of acoustic ceiling tiles to add mass to reduce the rattles from the grid caused by large subwoofer output... also the drywall panels are fairly absorptive at lower frequencies [about 30% at 125 Hz as I recall].


Or you could use a high NRC tile and a roll insulation topper.


I wouldn't consider a drywall ceiling unless noise isolation was an issue.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Scott R. Foster* /forum/post/11433445
> 
> 
> Or you could use a high NRC tile and a roll insulation topper.



This can actually work really well for HT sound, low frequency isolation issues aside. It puts a lot of very wideband absorption on the ceiling, improving lower frequencies than can be readily dealt with by typical wall treatment. By itself, this wouldn't handle lengthwise and widthwise reverberation very well, typically resulting in a double-slope decay curve (fast decay from heightwise room modes and slow decay from lengthwise and widthwise modes),with a long overall reverberation time. But if you have many uneven wall surfaces to diffuse the sound upwards and all around, the reverberation decay can become smooth and clean.


- Terry


----------



## mauitime

Here's my deal, I am renting a new house that has an unfinished basement; walls are concrete and ceiling is rafters. The room is 10x25 but am only gonna use about 10x20 for HT. I need something I can put up temporarily so it will look decent and sound decent until I can get a lease option on the house and do what I want with it!! I know most of the material is kinda expensive but is there anything I can "hang" up?


Thanks for any suggestions!


----------



## Petrucci

Is it better to use absorbtion directly to the left and right of the listening position or is it best to leave the wall untreated for proper surround effect?


----------



## nathan_h




> Quote:
> Originally Posted by *mauitime* /forum/post/11436426
> 
> 
> Here's my deal, I am renting a new house that has an unfinished basement; walls are concrete and ceiling is rafters. The room is 10x25 but am only gonna use about 10x20 for HT. I need something I can put up temporarily so it will look decent and sound decent until I can get a lease option on the house and do what I want with it!! I know most of the material is kinda expensive but is there anything I can "hang" up?
> 
> 
> Thanks for any suggestions!



Into the rafters in the ceiling, staple batts of fiberglass insulation, and then cover it all with acoustic fabric (doesn't have to be expensive Guildford of Maine stuff -- just anything dark and that you can blow air through).


Along the walls, especially at first reflection points, hang absorbing material -- could be acoustic foam, or buy some rigid fiberglass and cover in acoustic fabric.


One idea I've been thinking of is using curtains covering every wall floor to ceiling, of a lightweight (acoustically permeable, can blow through it) fabric -- and then putting ugly but effective treatments behind it all.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Petrucci* /forum/post/11436665
> 
> 
> Is it better to use absorbtion directly to the left and right of the listening position or is it best to leave the wall untreated for proper surround effect?



The first reflection points on the side walls (and ceiling and floor) should be treated with absorption. Left untreated your room will destroy surround effects, not enhance them.










--Ethan


----------



## Petrucci




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11438230
> 
> 
> The first reflection points on the side walls (and ceiling and floor) should be treated with absorption. Left untreated your room will destroy surround effects, not enhance them.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan




I have covered the first reflection points on the side walls but they do not extend all the way to the point directly to the right and left of the the listening position. I have enough treatment to cover that area also but I am afraid of having to much absorbtion.


----------



## mauitime




> Quote:
> Originally Posted by *nathan_h* /forum/post/11438126
> 
> 
> Into the rafters in the ceiling, staple batts of fiberglass insulation, and then cover it all with acoustic fabric (doesn't have to be expensive Guildford of Maine stuff -- just anything dark and that you can blow air through).
> 
> 
> Along the walls, especially at first reflection points, hang absorbing material -- could be acoustic foam, or buy some rigid fiberglass and cover in acoustic fabric.
> 
> 
> One idea I've been thinking of is using curtains covering every wall floor to ceiling, of a lightweight (acoustically permeable, can blow through it) fabric -- and then putting ugly but effective treatments behind it all.



Thanks Nathan! I am really trying to keep the cost down as with this much space I'm sure it can add up quickly.. I was also thinking of some sort of curtains with acoustical treatment behind.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Petrucci* /forum/post/11439274
> 
> 
> I have enough treatment to cover that area also but I am afraid of having to much absorbtion.



Better too much absorption than too little. To my way of thinking, the idea that the sound of your room should influence what you hear from the speakers is misguided. Small room ambience is generally bad sounding ambience. I'm not saying to make your room totally dead. But there's a good amount of leeway with this, and generally more absorption leads to cleaner sound that is _more_ realistic and lifelike.


--Ethan


----------



## Petrucci




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11447049
> 
> 
> Better too much absorption than too little. To my way of thinking, the idea that the sound of your room should influence what you hear from the speakers is misguided. Small room ambience is generally bad sounding ambience. I'm not saying to make your room totally dead. But there's a good amount of leeway with this, and generally more absorption leads to cleaner sound that is _more_ realistic and lifelike.
> 
> 
> --Ethan



Ok, Thanks for your expert advice Ethan. I will hang the rest of my treatments tonight.


----------



## Dennis Erskine

One can easily over deaden a room...be careful. Whether or not diffusion is used, or absorption is used, on the early reflection points is based upon the quality of the off axis response of the speakers.


----------



## CAK

What is the rule of thumb for acoustics in a small, 2 channel *ONLY* listening room (12wx14lx8h). Is it deaden front end, liven back or do I have that in reverse? Any tips or tricks you may suggest would be highly appreciated.


My seating position is an equilateral triangle 8' apart.


Thanks!


----------



## Petrucci




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/11451961
> 
> 
> One can easily over deaden a room...be careful. Whether or not diffusion is used, or absorption is used, on the early reflection points is based upon the quality of the off axis response of the speakers.



All of my fronts are Ascend 340s. They seem to be pretty good off axis. I added some more 2" absorbers to the left and right of the viewing postion last night and it definately made a difference. The bass seemed tigher with more clarity and the imaging was improved. I am still having problems flattening out the response on my sub but I may need to just break down and buy an EQ of some sort.


Thanks for your help guys.


----------



## gnolivos

I am looking for advice on a post-mortem fix for sound leaking through the A/C ducts. I spent quite a bit of money ($3,000) in double drywall + GG + insulation, so I think I must take care of this.


Unfortunately the ducts themselves were already in place when the build began, so I need a solution that will accomodate to the current state of things... Linacoustics would have been great, but not something I could apply to an enclosed ductwork...

Can someone point me in the right direction please? Anything is help... even if it just cuts the sound by half.


----------



## myfipie




> Quote:
> Originally Posted by *Petrucci* /forum/post/11458624
> 
> 
> All of my fronts are Ascend 340s. They seem to be pretty good off axis. I added some more 2" absorbers to the left and right of the viewing postion last night and it definately made a difference. The bass seemed tigher with more clarity and the imaging was improved. I am still having problems flattening out the response on my sub but I may need to just break down and buy an EQ of some sort.
> 
> 
> Thanks for your help guys.



You may need to get a EQ to flatten out some of the sub low frequencies, but you may want to add a few more bass traps (if you can) before hand. I may be over looking this but you only have 2 right now?


Glenn


----------



## Jon V

I have a basement theater 11' wide, 20' long and 92" high. 3 walls are treated up to 42" height with OC703, which has worked well for damping refletions. the 4th wall is bookcases and heavy floor to ceiling cabinet doors (faced partially with absorption panels. The back 6 feet of the room has a 9" riser for second row seats and is stuffed with fiberglass. The ceiling is also partially absorptive due to a home built star ceiling made with FRK OC 703 with the foil facing the room and partially removed in a sort-of checkerboard pattern.


Now its time for bass trapping. There is an AC soffit running down one side of the room. When i put up the crown molding, I left some space at the back of the room for a soffit bass trap that would be about 12" in height and 16" front to back, matching the size of the AC soffit. I have some 1" FRK OC 703 left over and was thinking about cutting and gluing 4 layers of it to form an L shaped soffit, covering it with GOM to match the stuff in the room now, and mounting it to look like the existing soffit.


Questions: Will this be an effective part of a bass trapping solution for the room? Should i remove the foil from the room-facing side of the 703? (i will remove from all the other layers). Should i stuff the inside cavity with additional fiberglass, like the stuff on rolls?


I plan to span the floor/rear wall intersection with 2'x4'x4" 703 panels and perhaps put Ethan's tricorner traps in the lower rear corners. There is no place to put bass traps at the front of the room as the right front 5' of the room is an open arch, the front12' on the left is the floor to ceiling cabinets and the screen is too close to the ceiling to put anything above it (also, the WAF thing).


----------



## Petrucci




> Quote:
> Originally Posted by *myfipie* /forum/post/11469273
> 
> 
> You may need to get a EQ to flatten out some of the sub low frequencies, but you may want to add a few more bass traps (if you can) before hand. I may be over looking this but you only have 2 right now?
> 
> 
> Glenn



Glenn,


I have two 4" absorbers in the front two corners and I lso built two 4" triangle traps for the ceiling corners.


----------



## Jon V




> Quote:
> Originally Posted by *nathan_h* /forum/post/11329765
> 
> 
> Very cool. Now I gotta figure out the weight thing.... I wonder if Home Depot carries balsa wood?



One homemade skyline diffuser i saw was made from stiff 2" thick exterior foam insulation - like the stuff you see at HD in 4x8 sheets. The guy cut 12 2" x 24" skyline profiles out of the stuff , then glued them together to form a 24" x 24" square. If you're careful, you can get 2 skylines out of one rectangle with one continuous cut. i think you can get hot wire cutters for that stuff at hobby shops. It would beat cutting 144 balsa sections and putting them together.


----------



## nathan_h

That's an interesting idea. I would have thought it would be too porous / absorbing -- but I suppose a little of that is not bad. Thanks!


----------



## myfipie




> Quote:
> Originally Posted by *Petrucci* /forum/post/11473066
> 
> 
> Glenn,
> 
> 
> I have two 4" absorbers in the front two corners and I lso built two 4" triangle traps for the ceiling corners.




I would put some more in first. Most rooms at minimum need 4 2x4s and really something more like 8 or more for the "wow" factor. All rooms are not the same, but 2 is a pretty small amount.


Glenn


----------



## Lindahl

If you have a fully treated (absorptive) front wall, and your speakers are all behind an AT screen, can you use black velvet across the rest of the entire fake screen wall? I would assume that if the black velvet is not reflective at all, then it's not any different than an acoustically transparent cloth, like speaker grill. However, I'm concerned that it may reflect some frequencies. Does anyone know if typical black velvet will reflect some sound, or if it is only absorptive and transparent across the entire frequency range?


----------



## pepar




> Quote:
> Originally Posted by *Lindahl* /forum/post/11509076
> 
> 
> If you have a fully treated (absorptive) front wall, and your speakers are all behind an AT screen, can you use black velvet across the rest of the entire fake screen wall? I would assume that if the black velvet is only absorptive, then it's not any different than an acoustically transparent cloth like speaker grill. However, I'm concerned that it may reflect some frequencies. Does anyone know if typical black velvet will reflect some sound, or if it is only absorptive and transparent across the entire frequency range?



If the black velvet is ONLY ABSORPTIVE, then it is not acoustically transparent and is ENTIRELY different than speaker grill cloth.


----------



## Lindahl




> Quote:
> Originally Posted by *pepar* /forum/post/11509722
> 
> 
> If the black velvet is ONLY ABSORPTIVE, then it is not acoustically transparent and is ENTIRELY different than speaker grill cloth.



You missed the entire point. If everything behind that passes through the material is absorbed, then, effectively, an absorbent material is no different than acoustically transparent material, because when the audio passes through the acoustically transparent cloth, it becomes absorbed.


----------



## pepar




> Quote:
> Originally Posted by *Lindahl* /forum/post/11510381
> 
> 
> You missed the entire point. Almost any cloth will be transparent below some frequency (not enough mass), hence a cloth really can't be only absorptive. I'm just worried about some frequencies that may be reflected by typical black velvets.



If I had read it after you edited it, I may not have.










I don't know where you'd find data on reflectivity. Transmission and absorption data, yes.


----------



## BasementBob

pepar:


Where is there absorption coefficients on velvet ?


(velvet is certainly absorptive, and is not acoustically transparent speaker cloth)




Lindahl:

I have no idea if velvet makes a good absorber cover. Nevertheless, that's what I used.
http://www.bobgolds.com/LivingRoomPl...ction/home.htm 

However I used it mostly so the surrounding space would be blackest black.


I believe SandmanX did exactly what you're proposing: speakers behind an acoustically transparent screen, and the rest of the front wall covered in black velvet.
http://www.smxscreen.com/images/curv...n/IMG_1441.jpg


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> Where is there absorption coefficients on velvet ?
> 
> 
> (velvet is certainly absorptive, and is not acoustically transparent speaker cloth)



My mistake. When he said "black velvet" I thought of felt. And Ethan recently was saying that felt was OK. Again, my mistake.










Lindahl: It would not have mattered if I had read your edited post, I *still* would have got it wrong.


----------



## Lindahl

No prob... any acousticians want to chime in on the suitability of black velvet in this application?


----------



## bpape

Felt is fine for in front of treatments. It is most definitely not recommended in front of speakers.


Bryan


----------



## Lindahl




> Quote:
> Originally Posted by *bpape* /forum/post/11524276
> 
> 
> Felt is fine for in front of treatments. It is most definitely not recommended in front of speakers.



Hmm, my concern was about velvet... did you mean velvet too? Or just felt?


----------



## caesar1

My room sounds okay as is, but would probably benefit, like most rooms, from acoustic treatment. Obviously, at a minimum, I would need panels or something at the first reflection points. Here is my room:

http://ericbeth.home.comcast.net/theater.html 


Now I read most of this thread, but most of it deals with DIY stuff. I'm not a DIY guy, but would like some cost effective acoustic treatment.


Who can you hire to decide what treatments (basic) your room needs acoustically and who will also actually put the stuff up (or get someone to do it)?


I'm not looking to spend a fortune, but I'm not looking to spend just a few hundred either.


----------



## eugovector

I'd imagine there are several folks in this thread who make treatments for a living who would love to help you out. If you're anywhere near Poughkeepsie, NY, I'll give you my opinion for what it's worth.


----------



## caesar1




> Quote:
> Originally Posted by *eugovector* /forum/post/11527471
> 
> 
> I'd imagine there are several folks in this thread who make treatments for a living who would love to help you out. If you're anywhere near Poughkeepsie, NY, I'll give you my opinion for what it's worth.



I'm in the Philadelphia suburbs.


----------



## eugovector

Well, so much for that then. My amateur opinion based only on your pictures is to fill the space above your ceiling with the pink fluffy stuff if you haven't already. If those aren't acoustic tiles, replace them with some that are, at least at your First reflection points. For your walls, if you're not DIY, get a couple panels from one of the suppliers in this thread and hang them at you first relection points on the side walls. Bonus points if you treat your front wall. Since the room is a pretty tight fit, use Bass Trapping in your front corners, and couple that with a parametric EQ. Check out the Behringer feedback destroyer and Room EQ Wizard on hometheatershack.com, or go with Velodyne if you want simple, yet expensive.


P.S. While I'm here, is anyone elses view of this forums screwed up? Here's what my screen looks like:  




Please PM me if you know what I'm doing wrong.


----------



## caesar1




> Quote:
> Originally Posted by *eugovector* /forum/post/11527660
> 
> 
> Well, so much for that then. My amateur opinion based only on your pictures is to fill the space above your ceiling with the pink fluffy stuff if you haven't already. If those aren't acoustic tiles, replace them with some that are, at least at your First reflection points. For your walls, if you're not DIY, get a couple panels from one of the suppliers in this thread and hang them at you first relection points on the side walls. Bonus points if you treat your front wall. Since the room is a pretty tight fit, use Bass Trapping in your front corners, and couple that with a parametric EQ. Check out the Behringer feedback destroyer and Room EQ Wizard on hometheatershack.com, or go with Velodyne if you want simple, yet expensive.
> 
> 
> P.S. While I'm here, is anyone elses view of this forums screwed up? Here's what my screen looks like:
> 
> 
> 
> 
> Please PM me if you know what I'm doing wrong.



Thanks, the ceiling tiles are acoustic and there is insulation in the ceiling joists (where possible -- as ductwork also runs through the ceiliing).


I'm most concerned with acoustic panels/fabric (wall treatments) at this point. I need someone to decide where the panels/fabric should go EXACTLY -- and who will also install them. What companies do that?


----------



## eugovector




> Quote:
> Originally Posted by *caesar1* /forum/post/11527725
> 
> 
> Thanks, the ceiling tiles are acoustic and there is insulation in the ceiling joists (where possible -- as ductwork also runs through the ceiliing).
> 
> 
> I'm most concerned with acoustic panels/fabric (wall treatments) at this point. I need someone to decide where the panels/fabric should go EXACTLY -- and who will also install them. What companies do that?



Well, "exactly" is easy, you and a buddy with a mirror get get the job done. Search "mirror trick". As for hanging them, you and a handheld drill, some screws, maybe a drywall anchor or two.


As for companies, Realtraps (Ethan) and GIK Acoustics (bpape) are well represented here, offering lots of free advice in this thread. Appologies to other contributing members in the business that I didn't mention, please make yourselves known.


----------



## caesar1




> Quote:
> Originally Posted by *eugovector* /forum/post/11527832
> 
> 
> Well, "exactly" is easy, you and a buddy with a mirror get get the job done. Search "mirror trick". As for hanging them, you and a handheld drill, some screws, maybe a drywall anchor or two.
> 
> 
> As for companies, Realtraps (Ethan) and GIK Acoustics (bpape) are well represented here, offering lots of free advice in this thread. Appologies to other contributing members in the business that I didn't mention, please make yourselves known.



I'm looking for a company that will actually do the installs (I don't even own a drill, nor would I know which kind to buy). From their websites I think these companies provide analysis and materials, but not installation of fabric or panels.


----------



## nathan_h

 http://rivesaudio.com/ can help you out. They can do the analysis remotely, and then give you the details (and probably names) to talk to, locally, to get their ideas implemented.


----------



## JimP

caesar1,


Where are you located??


You might want to add your location to your visible profile.


----------



## rossandwendy




> Quote:
> Originally Posted by *caesar1* /forum/post/11528184
> 
> 
> I'm looking for a company that will actually do the installs (I don't even own a drill, nor would I know which kind to buy). From their websites I think these companies provide analysis and materials, but not installation of fabric or panels.



If you can hang a piture on your wall, you can hang an acoustic panel







And corner bass traps just rest on your floor, no hanging. I am definitely not a DIY kind of guy and I totally understand where you are coming from here, but finding a local installer to do what you can do with a screwdriver is going to add a lot of labor costs (believe me, if I can hang a panel than anyone can, I am a real mechanical/tool idiot!).


I just worked with Glenn at GIK, emailed him pics of my room which he expertly analyzed and he came up with a game plan for basic treatment consisting of a total of 7 traps & panels with exact intructions of where to place each piece, all for about $950 delivered from the east coast to the west. I'll be setting them up when they arrive next week and am really looking forward to hearing the improvement in SQ.


Cheers,

Ross


----------



## caesar1




> Quote:
> Originally Posted by *JimP* /forum/post/11528460
> 
> 
> caesar1,
> 
> 
> Where are you located??
> 
> 
> You might want to add your location to your visible profile.



Philadelphia suburbs.


----------



## tonybradley




> Quote:
> Originally Posted by *caesar1* /forum/post/11528184
> 
> 
> I'm looking for a company that will actually do the installs (I don't even own a drill, nor would I know which kind to buy). From their websites I think these companies provide analysis and materials, but not installation of fabric or panels.



Who built your room for you? It's nice by the way.


Honestly, anyone with a knowledge of building a room, hanging speakers could do the work for you. I think a number of us could point you to step by step directions for making the panels and hanging them. Maybe you have a friend or family member that can help you...it would save a lot of money. I'm not very handy, so if I can do them, I know you could.


----------



## caesar1




> Quote:
> Originally Posted by *rossandwendy* /forum/post/11528547
> 
> 
> If you can hang a piture on your wall, you can hang an acoustic panel
> 
> 
> 
> 
> 
> 
> 
> And corner bass traps just rest on your floor, no hanging. I am definitely not a DIY kind of guy and I totally understand where you are coming from here, but finding a local installer to do what you can do with a screwdriver is going to add a lot of labor costs (believe me, if I can hang a panel than anyone can, I am a real mechanical/tool idiot!).
> 
> 
> I just worked with Glenn at GIK, emailed him pics of my room which he expertly analyzed and he came up with a game plan for basic treatment consisting of a total of 7 traps & panels with exact intructions of where to place each piece, all for about $950 delivered from the east coast to the west. I'll be setting them up when they arrive next week and am really looking forward to hearing the improvement in SQ.
> 
> 
> Cheers,
> 
> Ross




They send you panels already completely made and ready -- and you just hang them on the wall with a nail (like a picture)?


----------



## caesar1




> Quote:
> Originally Posted by *tonybradley* /forum/post/11528723
> 
> 
> Who built your room for you? It's nice by the way.



Thanks. This is a new construction home -- so I worked with the home builder on a custom partially finished basement -- including the home theater room. I gave the builder the basic specs as far as room size desired, the riser location, etc. (mostly from reading AVS) and I worked with the builder's electricians on placement of the speaker positions and projector and rack location for wiring purposes (as well as lighting).


After we closed on the house, we hired painters for the room colors (builder did every room in one basic color) and the place I bought my projector from did the projector, screen and speaker mounting.


This was my "construction" thread:

http://www.avsforum.com/avs-vb/showt...hlight=caesar1


----------



## Ethan Winer




> Quote:
> Originally Posted by *caesar1* /forum/post/11528754
> 
> 
> They send you panels already completely made and ready -- and you just hang them on the wall with a nail (like a picture)?



Yes, that's the way our RealTraps panels mostly work. If you're not handy at all you can probably find someone locally to do this for you for $100. But it's not that big a deal, even if you're all thumbs.










--Ethan


----------



## bpape

Lindahl.


Yes - that applies to velvet also. If a material is absorbtive, it is not suitable for in front of speakers. Many of GOM's materials themselves are not suitable. There are maybe 8-10 of them that are really transparent enough to put speakers behind.


Bryan


----------



## zmisst

On a DIY network show on home theaters, they showed construction using double drywall, hat channel, acoustic caulk and some other good things, but they also showed using rigid fiberglass panels BEHIND the double drywall.


They alternated every other panel so that it looks like this:











More info is at http://www.diynetwork.com/diy/hi_fam...208_02,00.html 


Does this work? Is there any benefit to putting rigid fiberglass panels behind the drywall on top of the r13 batts? They described it in the actual show, as I recall, as a kind of acoustic treatment -- not just sound isolation. sort of a bass trap behind the drywall. would that work?


----------



## Terry Montlick




> Quote:
> Originally Posted by *zmisst* /forum/post/11558767
> 
> 
> Does this work?



No. I'm afraid it was pure stupidity on the part of the TV show.










- Terry


----------



## pepar

Anybody??


I am preparing to make some changes in my home theater and would like some input. Along with lowering to a wee bit above ear level of my M&K S-150s and adding superchunk style bass traps, I am contemplating REMOVING or reducing the size of the front left & right first reflection point absorbers. They are now 4' x 4'. Lowering LCR would mean I could cover the points with 2' x 4' panels. The "removing completely" thought comes from reading Toole's June 06 AES paper (so kindly provided by TumaraBapp) and how lateral reflections are good. As I have black carpet on the wall (for light control), I would - I guess - be replacing the absorbers with diffusion.


I'd like to hear comments on what I am considering, including what diffusion I should use. Skyline LPs are so so expensive.


TIA!!


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/11560600
> 
> 
> The "removing completely" thought comes from reading Toole's June 06 AES paper (so kindly provided by TumaraBapp) and how lateral reflections are good.



This has been part of Floyd Toole's stump speech for the last few years. I think he makes these overstatements to shake up the professional acoustics community from their traditional complacency and indifference toward small room acoustics.


Early reflections will improve speech intelligibility in low-quality environments. They are of great benefit in classrooms, for example. But they will also lower the accuracy of front sound stage spacial imaging for a high-quality HT room. His and Sean Olive's 1988 paper demonstrated this "image shift" phenomenon pretty clearly.


- Terry


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/11560600
> 
> 
> Anybody??
> 
> 
> I am preparing to make some changes in my home theater and would like some input. Along with lowering to a wee bit above ear level of my M&K S-150s and adding superchunk style bass traps, I am contemplating REMOVING or reducing the size of the front left & right first reflection point absorbers. They are now 4' x 4'. Lowering LCR would mean I could cover the points with 2' x 4' panels. The "removing completely" thought comes from reading Toole's June 06 AES paper (so kindly provided by TumaraBapp) and how lateral reflections are good. As I have black carpet on the wall (for light control), I would - I guess - be replacing the absorbers with diffusion.
> 
> 
> I'd like to hear comments on what I am considering, including what diffusion I should use. Skyline LPs are so so expensive.
> 
> 
> TIA!!



Opinions differ, and I'm not an expert, but one line of thought is that in a larger room, for two channel music, diffusion would be ideal for what you describe. It would increase the sound stage width and depth.


But for surround sound, in a more modest room, the absorption at the first reflection points will keep the imaging focussed -- and you'll hear only the sound stage in the recording, with the room adding less to the character of the recording.


----------



## sdurani




> Quote:
> Originally Posted by *pepar* /forum/post/11560600
> 
> 
> The "removing completely" thought comes from reading Toole's June 06 AES paper (so kindly provided by TumaraBapp) and how lateral reflections are good.



Rather than an all or nothing approach, discussing Toole's paper with a friend got me to consider which first reflections I wanted to absorb and which I wanted to diffuse.


For example, I know I don't want to hear sounds from the right speaker coming from the left wall, because it'll mess with directionality. So I'll absorb the first reflection from the opposite speaker. However, I do like it when sound from my right speaker reflects off the right wall, because it helps widen the soundstage. So I'll diffuse the first reflection from the nearby speaker. The diffusion will keep the reflection from being a mirror image and causing image shifting (where sounds from the right channel will phantom image between the right speaker and its first reflection on the right wall).


I'm undecided on what to do with the first reflections from my centre speaker. For movies, absorbtion tends to make dialogue clearer. For music (which is what I use my system for primarily) diffusion seems to work better, helping the vocalist blend more naturally with the widened soundstage rather than be a crystal clear dot in the middle of it. This sometimes works well for movies, but I'm still experimenting.


BTW, the above assumes that your speakers maintain somewhat consistent tonality off-axis. If the frequency response of the first reflections is very different than what's coming directly from your speakers, then I would absorb them (the reflections, not the speakers). Don't get me wrong, I love a wide lush soundstage, but not if it's going to make a noticeable change to the sound of instruments and vocals.


Sanjay


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/11562121
> 
> 
> This has been part of Floyd Toole's stump speech for the last few years. I think he makes these overstatements to shake up the professional acoustics community from their traditional complacency and indifference toward small room acoustics.
> 
> 
> Early reflections will improve speech intelligibility in low-quality environments. They are of great benefit in classrooms, for example. But they will also lower the accuracy of front sound stage spacial imaging for a high-quality HT room. His and Sean Olive's 1988 paper demonstrated this "image shift" phenomenon pretty clearly.





> Quote:
> Originally Posted by *nathan_h* /forum/post/11562163
> 
> 
> Opinions differ, and I'm not an expert, but one line of thought is that in a larger room, for two channel music, diffusion would be ideal for what you describe. It would increase the sound stage width and depth.
> 
> 
> But for surround sound, in a more modest room, the absorption at the first reflection points will keep the imaging focussed -- and you'll hear only the sound stage in the recording, with the room adding less to the character of the recording.



My room is ~13' x 21' x 8', so it is not a large room. Going by what I heard as I installed my absorbers, the first one up - the rear wall - made a huge difference in the clarity and imaging of LCR and greatly improved surround/mains integration. The front left and right ones went up next and, while they made an improvement in both of those areas, it was incremental. The front ceiling was last and it also improved front imaging to a slightly greater degree than the left and right front absorbers. But with these, the 2" J-M Linacoustic lining the cavity behind the false wall, the six fat LaZBoys and the wall carpet to ear level all around, I feel that there is no "air" or at least not enough. The front sound stage is wide and deep, so I do not want to monkey with that.


Perhaps what I should start with is to lower LCR to close to ear level. They are higher now and aimed down at the 3D "center" of the seats and with the tight vertical dispersion - M&K S-150 THX (pre Select & Ultra) - I feel that I will get more even coverage. I already have 2' x 4' absorbers made, so it will be a simple matter to swap them with the 4' x 4' ones, and the smaller ones will be a closer match for the angles to the ears from the new location(s). And then I would like to try adding diffusion to the area above the 2' x 4' absorbers. The first reflection points will still be covered and perhaps I can increase the airiness. Have my cake and eat it, too.


Can you recommend some diffusors? I've been looking at Skyline LP, but they are very proud of them and command a price that just looks out of whack for what would seem to be a few dollars worth of styrofoam, if that. I will bite the bullet, though, if they are the right tool for the job.


Thanks for the advice.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *sdurani* /forum/post/11562574
> 
> 
> Rather than an all or nothing approach, discussing Toole's paper with a friend got me to consider which first reflections I wanted to absorb and which I wanted to diffuse.
> 
> 
> For example, I know I don't want to hear sounds from the right speaker coming from the left wall, because it'll mess with directionality. So I'll absorb the first reflection from the opposite speaker. However, I do like it when sound from my right speaker reflects off the right wall, because it helps widen the soundstage. So I'll diffuse the first reflection from the nearby speaker. The diffusion will keep the reflection from being a mirror image and causing image shifting (where sounds from the right channel will phantom image between the right speaker and its first reflection on the right wall).
> 
> 
> I'm undecided on what to do with the first reflections from my centre speaker. For movies, absorbtion tends to make dialogue clearer. For music (which is what I use my system for primarily) diffusion seems to work better, helping the vocalist blend more naturally with the widened soundstage rather than be a crystal clear dot in the middle of it. This sometimes works well for movies, but I'm still experimenting.
> 
> 
> BTW, the above assumes that your speakers maintain somewhat consistent tonality off-axis. If the frequency response of the first reflections is very different than what's coming directly from your speakers, then I would absorb them (the reflections, not the speakers). Don't get me wrong, I love a wide lush soundstage, but not if it's going to make a noticeable change to the sound of instruments and vocals.



Thank you, Sanjay. I like the thinking behind what you suggest, but with two front speakers - three if you count center channel - and six seats that I am trying like the dickens to have all be good seats - it seems too complex and perhaps not even doable. Absorption that would catch the right speaker's sound coming from the left wall to ears in the right rear seat would also absorb the left front speaker's sound going to the left rear seat.


You have made me think; I visited my theater two times over the course of typing this post and sat in several seats to visualize the angles.







I'd be interested in hearing any further comments you have on your experimentation.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/11562663
> 
> 
> Can you recommend some diffusors? I've been looking at Skyline LP, but they are very proud of them and command a price that just looks out of whack for what would seem to be a few dollars worth of styrofoam, if that.



I would never stoop so low as to recommend my own company's products.











The best diffusor would be rugged enough to withstand being bumped into without snapping into pieces, and would offer bass trapping at low frequencies where diffusion is not needed or useful.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11562854
> 
> 
> The best diffusor would be rugged enough to withstand being bumped into without snapping into pieces, and would offer bass trapping at low frequencies where diffusion is not needed or useful.



Teaching me how to fish; I like that.


----------



## BasementBob

sdurani:



> Quote:
> For example, I know I don't want to hear sounds from the right speaker coming from the left wall, because it'll mess with directionality.



I've experienced that particular one first hand -- well the left/right mirror of it.

I was watching the Star Wars Pod Race, and couldn't tell where the pods were coming from. Turned out the left speaker was bouncing off the right wall. I put an absorber by my right shoulder, and bingo imaging was MUCH MUCH better.


----------



## Lindahl




> Quote:
> Originally Posted by *sdurani* /forum/post/11562574
> 
> 
> However, I do like it when sound from my right speaker reflects off the right wall, because it helps widen the soundstage.



I don't want on-screen action to sound like it's happening off-screen. While this may be nice for music, I find this effect to ruin the immersion aspect of movies. I can barely stand having my speakers just barely outside my screen (which will soon be remedied with an AT screen). For music, yes, an artificially wide soundstage can be nice. But this is all the more reason to have separate rooms, if it's feasible.


----------



## sdurani




> Quote:
> Originally Posted by *pepar* /forum/post/11562761
> 
> 
> I like the thinking behind what you suggest, but with two front speakers - three if you count center channel - and six seats that I am trying like the dickens to have all be good seats - it seems too complex and perhaps not even doable.



I can't imagine doing it successfully for multiple seats. I just do it for the sweet spot and let the other seats fall where they may. Same for time alignment, levels calibration, speaker placement, toe-in, etc. I can't do all that based on a sweet spot and then pretend the other seats are equally important.


Since there is one location from where I calibrate, that's the seat I keep in mind for the rest of the set-up. It doesn't mean the other seats sound bad, just that "all good seats" to me means all seats compromised. I'd rather have one optimized seat in there. YMMV.


Sanjay


----------



## sdurani




> Quote:
> Originally Posted by *Lindahl* /forum/post/11563424
> 
> 
> I don't want on-screen action to sound like it's happening off-screen.



Not everything in the front L/R channels is meant to be on-screen, since sound mixers vary in their approach.


There's a scene at the begining of the movie _'Speed'_ where a phone is ringing off-screen and the camera pans to bring it on-screen. The sound itself starts in the left channel and moves to the centre channel. If you spread your speakers way outside the screen, it sounds much more natural than having the sound of an off-screen object come from where your screen is.


There are other movies where the L/R channels define the limits of the image. For that, it would be better to have the L/R speakers within the edges of the screen. But there is no consistency. You have to choose what type of set-up you prefer, and live with it for both types of mixes.


> Quote:
> _For music, yes, an artificially wide soundstage can be nice._



What do you mean by "artificially" wide soundstage? Like when an orchestra sounds like it is larger than the width of my living room? I think it would sound more artificial, at least to me, if the entire soundstage was limited to the spread of my front L/R speakers. I think this comes down to personal taste, both for music and movies.


Sanjay


----------



## Lindahl




> Quote:
> Originally Posted by *sdurani* /forum/post/11565669
> 
> 
> There's a scene at the begining of the movie _'Speed'_ where a phone is ringing off-screen and the camera pans to bring it on-screen. The sound itself starts in the left channel and moves to the centre channel. If you spread your speakers way outside the screen, it sounds much more natural than having the sound of an off-screen object come from where your screen is.



True, but I've found it infinitely more distracting when on-screen action sounds off-screen. It's the whole "your brain sees one thing, your ears hear another" conflicting of the senses that really rattles my cage. When the action is off screen, and the sound is on-screen, it's like pyschoacoustics kicks in, and it's a lot less distracting (maybe because the brain shifts what you thought you heard?). It could also be because the eyes are more precise in locating something than the ears, so your brain will discard the locational cues from your ears? Who knows... all I know is that I don't notice those problems. However, I do *really* notice the other mismatch.



> Quote:
> What do you mean by "artificially" wide soundstage? Like when an orchestra sounds like it is larger than the width of my living room?



No, not that kind of artificial. Artificial because the sound is coming from well outside the placement, due to the wall artificially expanding it.


----------



## sdurani




> Quote:
> Originally Posted by *Lindahl* /forum/post/11566410
> 
> 
> True, but I've found it infinitely more distracting when on-screen action sounds off-screen.



I've had the opposite reaction, probably because I think of the soundstage as being a seamless circle extending around me and the screen as a window seeing only part of it. When watching a movie, I'm used to sounds continuously imaging off-screen (outside my front L/R speakers, at my sides, behind me, etc).


> Quote:
> _Artificial because the sound is coming from well outside the placement, due to the wall artificially expanding it._



Understood. But that's no more artificial than having phantom imaging outside your mains due to blending with the surround speakers or decorrelated sounds in the front channels or certain speaker designs or anything else that causes the soundstage to extend beyond speaker placement. Home audio is an artificial construct to begin with. I don't see why limiting the soundstage between a couple of arbitrary points (the distance between your L/R mains) is any less artificial than having the soundstage extend wider.


Sanjay


----------



## JimP

I would think the difference would involve having phantom imaging placed where they're intended to be versus where they show up by mistake due to unintended reflections.


----------



## Lindahl




> Quote:
> Originally Posted by *sdurani* /forum/post/11567477
> 
> 
> I've had the opposite reaction, probably because I think of the soundstage as being a seamless circle extending around me and the screen as a window seeing only part of it. When watching a movie, I'm used to sounds continuously imaging off-screen (outside my front L/R speakers, at my sides, behind me, etc).



I suppose it has to do with the size of the screen. My screen almost fills my peripheral vision (2.35 AR). If I see something happen on-screen and it sounds like it's off-screen, then it destroys this immersion. Even if you consider the soundstage to be a seamless circle, around you, then only the action that happens off screen should sound like it's coming off-screen. If the sound needs to image off-screen, it should be softly matrixed (and almost always is) with the surrounds. Sound engineers mix for the theater, in which the front speakers are behind the screen. They very rarely mix on-screen action with off-screen sound.



> Quote:
> Originally Posted by *JimP* /forum/post/11567802
> 
> 
> I would think the difference would involve having phantom imaging placed where they're intended to be versus where they show up by mistake due to unintended reflections.



Yes, this is what I mean.


----------



## BasementBob

sdurani and Lindahl:



> Quote:
> There's a scene at the begining of the movie 'Speed' where a phone is ringing off-screen and the camera pans to bring it on-screen. The sound itself starts in the left channel and moves to the centre channel. If you spread your speakers way outside the screen, it sounds much more natural than having the sound of an off-screen object come from where your screen is.



With a 2.35:1 aspect ratio and constant height, and most movies being 16:9, most times the left/right speaker behind an acoustically transparent screen would be outside of the image.

So, I looked it up.

"Speed (1994)" - Aspect Ratio: 2.35:1

Oh well.


----------



## sdurani




> Quote:
> Originally Posted by *Lindahl* /forum/post/11569392
> 
> 
> I suppose it has to do with the size of the screen.



Sure. If I stretched my screen to the width of the soundstage I hear, then the soundstage wouldn't extend beyond the screen.


> Quote:
> _If the sound needs to image off-screen, it should be softly matrixed (and almost always is) with the surrounds._



What should be done is not always what is done. There was an on-line article I read years ago where lots of soundtracks were compared in order to figure out optimal front speaker placement. Turned out that roughly half the tracks had sounds in the L/R channels for off-screen action while half used the L/R channels to define the limits of the sceen. There was no consistency in mixing philosophy. So placing the speakers within screen boundries and placing them outside the screen both had compromises, depending on soundtrack. Made it impossible to for them to conclude a right or wrong placement; they ended up going on personal preference, which included what was less distracting for each individual.


Sanjay


----------



## Lindahl




> Quote:
> Originally Posted by *sdurani* /forum/post/11570595
> 
> 
> Turned out that roughly half the tracks had sounds in the L/R channels for off-screen action while half used the L/R channels to define the limits of the sceen.



That's not at all been my experience, but eh, oh well.


----------



## stanger89




> Quote:
> Originally Posted by *BasementBob* /forum/post/9145292
> 
> 
> Kermie:
> 
> 
> 
> http://www.bobgolds.com/Mode/RoomModes.htm
> 
> 
> 
> 
> A sabin can be defined loosly as "an open window one square foot in size".
> 
> So, if you have a material that absorbs 100% of the sound at all frequencies, and you need *413 sabins*, then you'd need 413 square feet of that material.
> 
> 
> For HF absorption, the above line
> 
> (sabins - front wall - carpet) / Left+Right+Rear wall: 30 %
> 
> means assuming you have the front wall and floor completely covered, then you should cover about 30% of the left/right/rear walls with HF absorption, assuming there's nothing else in the room.
> 
> 
> In practice, different materials absorb different amounts per frequency band (as well as placement, diminishing returns, etc)
> 
> For example carpet tends to absorb lots of HF, and less LF.
> 
> Leather couches tend to reflect HF, and absorb more around 200hz.
> 
> Your walls tend to reflect HF, and absorb low frequency.
> 
> What you want to do is add up the sabins for each frequency band, and add (or possibly remove) material until you hit around 413 sabins.
> 
> I say 'around' because who can really tell the difference between RT60=.20 and RT60=.30.
> 
> Once you have the right amount of material in the room, then it's a question of placing it to deal with other things. You don't want to put it all on one wall for example. Imaging might be improved if you put it on the front wall and first reflection points (particularly the absorber on the right wall at the left front speaker reflection point).
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> http://www.bobgolds.com/Sabin.htm



Hey all, apologies for not reading the whole thread but I'm looking into improving/fixing the acoustics in my HT, and at the moment, I'm trying to figure out how much absorption I need, and I'm having a little trouble narrowing down the more scientific methods to do it.


Starting with what I know, I've got a (roughly) 24x40 basement that houses my HT. Of that, roughly a 12 x 20 corner of that is closed off (half in both directions) portion, and opposite that, is a stair well (closed under solid walls, no door). So basically I've got a 12x40 "room" that makes up the HT with a stair well in the back, and that room opens up (via an 8' opening) into another

12x20 room. The two room form basically and open L but broken up by the stair well. About 7.5' ceilings.


Floor is shag carpet on pad. Walls are framed sheetrock, drop ceiling.


So I've been playing with ETF a bit, with my Galaxy 140 SPL meter as the mic and I get an RT60 of up to 3 seconds over much of the bass range (not entirely convinced the wiring is up to snuff for ETF), but that does somewhat jive with the "snap" or clap test, I can hear a snap reverberate for probably 2 seconds.


The big question I have is I see things like: "Absorbtion to achieve ITU RT60: 1112 sabins". Problem is (if I understand right) RT60 is a function of frequency, not a simple number. So I'm having a bit of trouble reconciling the two.


Is it (for example) RT60(f) = k * V / S(f)? With RT60 and Sabines being functions of frequency? Do you go through and say "I need x Sabines at this frequency and y Sabines at this other frequency?


Assuming my RT60 graph is right, and my basement is 7200ft^3, if I've got an RT60(400Hz) = 1400ms, (1400ms-200ms)=0.049*7200/S, so S = 252 Sabines currently @ 400Hz. If I want an RT60(400Hz) = 200ms, that would be 1764 Sabines? So I would need to add absorbtion "worth" ~1500 Sabines @ 400Hz? Looking at GIK 244 panels , that would be about 100 panels?


Is that right, mathematically (ignoring for the moment if an RT60 of 1.4s is reasonable, or if 7200ft^3 is reasonable for my setup) or am I horribly lost?


----------



## BasementBob

stranger89



> Quote:
> The big question I have is I see things like: "Absorbtion to achieve ITU RT60: 1112 sabins". Problem is (if I understand right) RT60 is a function of frequency, not a simple number. So I'm having a bit of trouble reconciling the two.



When the page says "Absorbtion to achieve ITU RT60: 1112 sabins", what it means is

1112 sabins at 63hz

1112 sabins at 125hz

1112 sabins at 250hz

1112 sabins at 500hz

1112 sabins at 1000hz

1112 sabins at 2000hz

1112 sabins at 4000hz



I believe that in a pre-build, that RT60 calculations are a useful and simple to understand metric to give you a starting point.

There are better models for pre-build.


For post-build, you'll find that your RT60 calculations will not match any measurements, and it's debateable if RT60 is something that even exists by it's definition and assumptions in a room as small as an HT.


And then there's ETF. You should talk to the author of that program for his opinions on RT60 measurements, and how to do them. ETF's RT60 measurements I never was happy with. R+D's (the successor to ETF by the same author) are supposed to be a little better. Even still, focusing on RT60 as a post-build room tuning isn't something I'd start with. ETF/R+D are great for proving lots of room hypothesis, as well as before/after changes, using measurements other than RT60.


----------



## stanger89

So it assumes a flat RT60? That makes sense.


So in reality, if I've got the real, measured RT60 curve for my room, at each frequency it's:


Sabins for recommended RT60 - Sabins calculated from measured RT60 = Sabins needed


Roughly?


Thanks for the quick response


----------



## BasementBob




> Quote:
> So it assumes a flat RT60? That makes sense.



Yes, it assumes a flat RT60.

Note that the RT60 curve doesn't have to be flat -- a little longer in the low isn't a problem. There's graphs about the acceptable limits somewhere. And I think that page lists some of them, although the wording is a bit cryptic.


(BTW, I edited the above post a bit)


----------



## Dennis Erskine




> Quote:
> The "removing completely" thought comes from reading Toole's June 06 AES paper (so kindly provided by TumaraBapp) and how lateral reflections are good.



There's a "yeah, but" here. In speaking with Floyd, he thinks this whole topic is a worthy PhD project. His recent work suggests these reflections can be good and they can be bad. Bad particularily if the off-axis response of the speakers happens to be poor. The threshold, and mechanism, between what makes them "good" and what makes them "bad" is not clearly understood (from not only the physics of what's going on; but, the psychoacoustics as well). It all rather falls into this rather broad category of small room acoustics and more specifically into the entire spectral decay issues (in small rooms). So, if anyone wants a PhD topic, here it is. (I'm tempted







)


----------



## stanger89




> Quote:
> Originally Posted by *BasementBob* /forum/post/11625803
> 
> 
> And then there's ETF. You should talk to the author of that program for his opinions on RT60 measurements, and how to do them. ETF's RT60 measurements I never was happy with. R+D's (the successor to ETF by the same author) are supposed to be a little better. Even still, focusing on RT60 as a post-build room tuning isn't something I'd start with. ETF/R+D are great for proving lots of room hypothesis, as well as before/after changes, using measurements other than RT60.



Hm, for some reason I didn't get an email to about the replies... Oh well.


Thanks again the responses. As far as ETF goes, it's more a case of, I know there's something wrong, both based on my own "clap" tests (long reverb) and noticing that my system sounds increasingly harsh at higher volumes which if I'm reading this thread right, could be attributed to the increasing audibility of decay issues at higher volumes.


So, I figured I'd play with ETF a bit to see if I can confirm some of the problems I suspect and get an idea for "where" they are and a rough magnitude of how big they are.


Oh, and in searching for "acceptable RT60 curve" I ran across this very interesting paper:
http://www.acousticsciences.com/arti...-acoustics.pdf 


Reading it now, looks like it might be exactly what I'm looking for...


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/11627589
> 
> 
> There's a "yeah, but" here. In speaking with Floyd, he thinks this whole topic is a worthy PhD project. His recent work suggests these reflections can be good and they can be bad. Bad particularily if the off-axis response of the speakers happens to be poor. The threshold, and mechanism, between what makes them "good" and what makes them "bad" is not clearly understood (from not only the physics of what's going on; but, the psychoacoustics as well). It all rather falls into this rather broad category of small room acoustics and more specifically into the entire spectral decay issues (in small rooms). So, if anyone wants a PhD topic, here it is. (I'm tempted
> 
> 
> 
> 
> 
> 
> 
> )



So this is just an academic exercise? I need to formulate a plan now based on what is known now, not what might be sussed out in the future. My M&K S-150s are to have wide and even horizontal dispersion, but I still can't grok how my experience will be better by hearing a reflection delayed from 5ms to 12ms (due to the additional distance of "LCR to front side wall to my ears"). When I reduce the size of my absorbers there due to leveling out LCR vis-a-vis the listeners, I need to mount something over the newly exposed carpeted wall. What choice do I have other than diffusion? And then WHAT diffusors do I use? 1D or 2D?


----------



## BasementBob

stanger89:


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/11632416
> 
> 
> stanger89:



This is relative. Is there an absolute recommendation? THX recommends 300ms midband decay.


----------



## BasementBob

pepar:

http://www.bobgolds.com/Mode/RoomModes.htm 

calculates all these things for you, as well as the IEC and ITU RT60 ranges for frequencies (a little different than the above graph).


The ITU RT60 specification for rooms 
Control Room Recommended RT60 = 0.3 *{(volume cu ft / 3531.34 cu ft) raised to 1/3 power}

Control Room Recommended RT60 = 0.25 * (( ProposedRoomVolume / 100 m^3 ) ^ .3333)

(1 cubic foot = 0.0283168 cubic meter)


This is the value I'd use for 500hz in the above graph.



ITU RT60

v, RT60 if V m^3, RT60 if V ft^3

i.e. if you calculate your room volume in ft^3, then go down the 1st column and find the volume of your room, and then get the RT60 from the 3rd column.

if you calculate your room volume in m^3, then go down the 1st column and find the volume of your room, and then get the RT60 from the 2nd column.

63 1.8 0.07 (shower stall - waterproof acoustical treatment required?)

1000 28.3 0.16

1250 35.4 0.18

1500 42.5 0.19

1750 49.6 0.20 (approximately 16' x 16' x 7')

2000 56.6 0.21

2250 63.7 0.22

2500 70.8 0.22

2750 77.9 0.23

3000 85.0 0.24

3250 92.0 0.24

3500 99.1 0.25

3750 106.2 0.26

4000 113.3 0.26

4250 120.3 0.27

4500 127.4 0.27

4750 134.5 0.28

5000 141.6 0.28

5250 148.7 0.29

5500 155.7 0.29

5750 162.8 0.29

6000 169.9 0.30

6250 177.0 0.30

6500 184.1 0.31

6750 191.1 0.31

7000 198.2 0.31

7250 205.3 0.32

7500 212.4 0.32

7750 219.5 0.32

8000 226.5 0.33

8250 233.6 0.33

8500 240.7 0.34

8750 247.8 0.34

9000 254.9 0.34

9250 261.9 0.34

9500 269.0 0.35

9750 276.1 0.35

10000 283.2 0.35

11000 311.5 0.37

12000 339.8 0.38

13000 368.1 0.39

14000 396.4 0.40

15000 424.8 0.40

16000 453.1 0.41

17000 481.4 0.42

18000 509.7 0.43

19000 538.0 0.44

20000 566.3 0.45

22500 637.1 0.46

25000 707.9 0.48

27500 778.7 0.50

30000 849.5 0.51

32500 920.3 0.52

35000 991.1 0.54

37500 1061.9 0.55

40000 1132.7 0.56

50000 1415.8 0.60

60000 1699.0 0.64

70000 1982.2 0.68

80000 2265.3 0.71

90000 2548.5 0.74

100000 2831.7 0.76

125000 3539.6 0.82

150000 4247.5 0.87

175000 4955.4 0.92

200000 5663.4 0.96

225000 6371.3 1.00 (approximately 100' x 100' x 22')



> Quote:
> THX recommends 300ms midband decay



On the above list, 0.3 seconds is at 6000 ft^3, or about a 24x24x10 room.


----------



## stanger89




> Quote:
> Originally Posted by *BasementBob* /forum/post/11632416
> 
> 
> stanger89:



Thanks!


That paper didn't turn out to be quite as helpful as I thought. But I did find Ethan's writeup on ETF so I'll give some of those suggestions a try and see if I end up with anything more reasonable.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/11633276
> 
> 
> pepar:
> 
> http://www.bobgolds.com/Mode/RoomModes.htm
> 
> calculates all these things for you, as well as the IEC and ITU RT60 ranges for frequencies (a little different than the above graph).



Wow, that'll keep me occupied for a while! Thanks!


----------



## WaveyD4vey

heres my situation guys...ive got two windows that i need to treat to prevent sound from getting out...i know its almost impossible to make them "sound proof" but i need something to hang over them that would help deaden the sound that blasts out of them and into the neighbors houses...hehe...any ideas?


----------



## eugovector




> Quote:
> Originally Posted by *WaveyD4vey* /forum/post/11773338
> 
> 
> heres my situation guys...ive got two windows that i need to treat to prevent sound from getting out...i know its almost impossible to make them "sound proof" but i need something to hang over them that would help deaden the sound that blasts out of them and into the neighbors houses...hehe...any ideas?



Simply hanging a heavy curtain will do a little to help the sound from getting out, but very little. Mostly, it will be good for keeping light out.


Best solution, close your windows. If that doesn't work, and you're sure the noise is leaking through your windows, you can cut a styrofoam or other hard foam piece to fit the window cavity.


Odds are though, all of these will have little effect if your HT is being heard from houses away. Move it to the basement, and build a soundproof room.


----------



## BasementBob

eugovector:


Styrofoam won't help either.

http://www.bobgolds.com/Window/Windo..._home_win1.gif 
http://www.bobgolds.com/Window/Windo...eShea_pg67.jpg


----------



## cuzed2

Good Morning,


I am trying to salvage some acoustical qualities for my basement theater/game room project. I do plan to finish the space with consideration for all practical acoustical treatments (absorption, reflection, diffusing sound, etc,etc...). I am not terribly worried about sound leaking out to the surronding areas - I just want to optimize the acoustics within the theater area of this open floor plan.


I am now at the point of framing my screen wall and have some basic layout questions that may be of acoustical benefit later on:


From the sketch and photos below:





























In the upper RH corner, to the right of my screen, I will need to frame and box-in some plumbing, my water meter is in this space. This will result in a 22" wide x 6' deep bump-out to the RH side of my screen.


I'm thinking I might gain an acoustical advantage (at the cost of floor space) if I were to put a matching wall like structure to the LH side of the screen?


What does everyone think, well this help acoustically?


I was also thinking of filling a portion of this hollow space to end up with bass traps?


Open to all suggestions (and your questions) that will help me in optimizing this open floor plan?


Thanks

CuzEd2 - Craig


----------



## yngdiego

I'm looking to turn a 10'W x 11'L x 8'H bedroom into a cozy HT. I've been reading this thread, and I'm at the point of information overload. The room is located upstairs with solid Sheetrock on all sides and plush carpet.


I will be mounting my 50" plasma on one wall, and will be using a 5.1 speaker setup for purely movies/TV (no stereo music). Speakers are the Energy Veritas line with a HSU VTF-3 subwoofer.


I did the "clap" test in the room and yikes, there is a lot of ringing in the room. So I know it needs some serious acoustic help.


From my reading, it sounds like I should start with the front wall. Now I'm a bit confused on how much of the wall I should cover and with what. Floor to ceiling with 1" OC 703 wrapped in cloth? Or should I alternate different panel types for broader frequency coverage? Or just panels half way up the wall?


It also sounds like in this small of a room that ceiling treatments are not recommended. Can I start with just treating the front wall, then see how it sounds and add additional treatments? Or are the room dimensions such that I seriously need more to really accomplish much of an improvement?


Sorry for the noob questions.


----------



## Ethan Winer

Guys,


Start here:

http://www.ethanwiner.com/acoustics.html 


Then follow up with any questions. Yes, left-right symmetry is important, as is reducing ringing and bass resonances.


--Ethan


----------



## cuzed2

Ethan,


Thanks for the link containing the tutorial. I skimmed it and am printing for more leisurly reading later.


I believe I will go ahead and build out both front corners for better symmetry (both acoustically and to be more visually balanced).


Thanks Again

Cuzed2 - Craig


----------



## mobius

I have some spare 1" CertainTeed 475 Ultra Duct Gold that I want to play around with. If I'm making panels for my front wall (where my projector screen is) should I remove the foil backing or just face it towards the wall?


EDIT: I assume the foil backing is similar to OC's "FRK" backing material.


TIA


----------



## cuzed2

As you can see I have taken your advice


I have since gone ahead and balanced the screen area by "boxing" in both sides.

This leaves cavities about 18" deep on both sides of the screen, floor to ceiling high, and about 6' from the front edge back to the screen wall.


Looking for suggestions on how best to treat (fill) these caivities - bass traps. etc ???


Thanks in advance!

CuzEd2 - Craig


----------



## Terry Montlick




> Quote:
> Originally Posted by *mobius* /forum/post/11849334
> 
> 
> I have some spare 1" CertainTeed 475 Ultra Duct Gold that I want to play around with. If I'm making panels for my front wall (where my projector screen is) should I remove the foil backing or just face it towards the wall?
> 
> 
> EDIT: I assume the foil backing is similar to OC's "FRK" backing material.
> 
> 
> TIA



You can leave the foil if it faces the wall. Sound passing through the fiberglass won't "see" any difference between a layer of sheetrock and a layer of sheetrock with a thin layer of foil directly covering it.


- Terry


----------



## mobius




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/11853252
> 
> 
> You can leave the foil if it faces the wall. Sound passing through the fiberglass won't "see" any difference between a layer of sheetrock and a layer of sheetrock with a thin layer of foil directly covering it.
> 
> 
> - Terry



Thanks a bunch Terry. I'll just leave the foil on then. They'll be spaced off the wall roughly 1" as I plan on using a french cleat to mount them.


----------



## MarkMac




> Quote:
> Originally Posted by *mobius* /forum/post/11853762
> 
> 
> Thanks a bunch Terry. I'll just leave the foil on then. They'll be spaced off the wall roughly 1" as I plan on using a french cleat to mount them.



Uhhh...I'll wait for someone much more knowledgeable to answer this, but I believe if you are going to have a space between the wall and the treatment, then you would want to remove the foil. If it were right up against the wall, then foil or not wouldn't matter since sound would reflect off the wall regardless of whether it were the foil or drywall; however, with a 1" space behind the treatment, removing the foil will have an impact.


----------



## Terry Montlick




> Quote:
> Originally Posted by *MarkMac* /forum/post/11864513
> 
> 
> Uhhh...I'll wait for someone much more knowledgeable to answer this, but I believe if you are going to have a space between the wall and the treatment, then you would want to remove the foil. If it were right up against the wall, then foil or not wouldn't matter since sound would reflect off the wall regardless of whether it were the foil or drywall; however, with a 1" space behind the treatment, removing the foil will have an impact.



Yup, exactly. I guess what I said to mobius was not completely unambiguous: _"a layer of sheetrock with a thin layer of foil directly covering it"_. This does not mean you can add an air space in between foil and sheetrock!


Regards,

Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *MarkMac* /forum/post/11864513
> 
> 
> with a 1" space behind the treatment, removing the foil will have an impact.



There's no real detriment to having foil in the rear of a panel, even if it's spaced off the wall. I've tested this in a lab, and it works fine. If anything, you'll get even more bass absorption, as well as no reduction in HF absorption.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11868200
> 
> 
> There's no real detriment to having foil in the rear of a panel, even if it's spaced off the wall. I've tested this in a lab, and it works fine. If anything, you'll get even more bass absorption, as well as no reduction in HF absorption.
> 
> 
> --Ethan



Would there not be more absorption at a certain band of bass frequencies due to diaphragmatic action, but less at others due to them not passing through the panel two times?


----------



## jay131011

yngdiego-


Let me know how your room sounds with the energies, my ht room is 13x15 and was told the vientas would be to much for my room to accomadate.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/11868439
> 
> 
> Would there not be more absorption at a certain band of bass frequencies due to diaphragmatic action, but less at others due to them not passing through the panel two times?



Sure, but the main difference is the amount of absorption at high frequencies on the face exposed to the room.


--Ethan


----------



## yngdiego

I'm trying to work out the optimal acoustic treatments for the room below. Basically it's a small bedroom and not many placement options. Drawing is to scale, where one small block is 4 inches. The angled lines you see under the drawing are the Dolby 5.1 recommended angles for placement of speakers.


Equipment:


Onkyo 905 Receiver

Pioneer 1150HD 50" Plasma

Energy Veritas speakers (v2.4, 2.0C, 2.0R)

HSU VTF-3 subwoofer

DTV HR20-100


Room:

Upstairs bedroom, two outside walls, plush carpet, sheetrock walls, 8' ceilings. Approximately 105 degrees to the rear surrounds.


My design reflects a 6.5' equilateral triangle between speakers and primary listening position, plus 6.'5 to the center speaker. Viewing distance is 7.5'. TV and center speaker are on a stand, so their relative distances cannot change. Rear surrounds are as far back into the room as possible given the door placement.


Questions:

1. The bass traps in the front corners eat up a TON of space and thus the front speakers are very close to them. Is this a significant problem? I know 1' from the back wall is recommended but this room is tiny. Toeing the speakers makes it that much worse.


2. On the left and right sides of the window I would have about one foot where I could put acoustic panels. Is that worth it? I plan to have drapes over the window. Should they be 2" or 4" OC703?


3. Should I put an acoustic panel directly under the window behind the center channel? It would be about 22" high. 2" or 4" OC703?


4. (Not on diagram). On the left and right walls at the reflection points one web site recommended a horizontal 2'x'4 panel, but my speakers are 45" high. Should they be vertical instead? 2" or 4" OC703?


5. (Not on diagram) In addition the site recommended two 2'x4' ceiling panels directly over the L and R main speakers, PLUS two more centered towards the middle of the room between the loveseat and TV. I've read elsewhere that in a room as small as mine, ceiling treatments are usually not needed. Four panels seems like a lot to me. Ideas?


6. Should the back wall in the closet get any treatments such as bass traps?


7. Do I need any diffusion panels?


Any and all feedback is appreciated. The room has pretty bad slap echo, BTW. Thanks!


----------



## eugovector




> Quote:
> Originally Posted by *yngdiego* /forum/post/11882650
> 
> 
> 
> 
> 
> Questions:
> 
> 1. The bass traps in the front corners eat up a TON of space and thus the front speakers are very close to them. Is this a significant problem? I know 1' from the back wall is recommended but this room is tiny. Toeing the speakers makes it that much worse.
> 
> 
> 2. On the left and right sides of the window I would have about one foot where I could put acoustic panels. Is that worth it? I plan to have drapes over the window. Should they be 2" or 4" OC703?
> 
> 
> 3. Should I put an acoustic panel directly under the window behind the center channel? It would be about 22" high. 2" or 4" OC703?
> 
> 
> 4. (Not on diagram). On the left and right walls at the reflection points one web site recommended a horizontal 2'x'4 panel, but my speakers are 45" high. Should they be vertical instead? 2" or 4" OC703?
> 
> 
> 5. (Not on diagram) In addition the site recommended two 2'x4' ceiling panels directly over the L and R main speakers, PLUS two more centered towards the middle of the room between the loveseat and TV. I've read elsewhere that in a room as small as mine, ceiling treatments are usually not needed. Four panels seems like a lot to me. Ideas?
> 
> 
> 6. Should the back wall in the closet get any treatments such as bass traps?
> 
> 
> 7. Do I need any diffusion panels?
> 
> 
> Any and all feedback is appreciated. The room has pretty bad slap echo, BTW. Thanks!



1. You could give yourself a little breathing room by going superchunk style.


2. I think most folks would say that in a room that small, Yes, Every little bit on your front wall will help to keep reflect sound from bouncing back from your primary sound source. I'm no (insert title of one who excels at geometry), but it looks like the angles aren't quite right for a centered seating position, but those sitting on the sides will reap the benefits since that would be a first reflection point for you mains and center. 2" should be fine.


3. For the same reasons, I think so. Is you center channel free standing or tucked in an equipment stand? Center channels tend to sound better if they aren't living in a box, but are out in the open, free to breathe.


4. Use the mirror trick to find the First Reflection points for your tweeters and mids at all seating locations. If it takes 2 panels on each wall, make sure you cover them all.


5. I still haven't put up my ceiling panels, so I can't tell you from personal experience, but at the 2007 HES, Richard Bird of Rives Audio cited a study that found that the ceiling was the most important spot to treat. I'd at least hit the Front Reflection for you 3 front speakers and you main seating location.


6. Does the closet have a door? If so, you may actually want to treat the door.


7. I think the rule I was quoted by auralex (I should have written it down) was that you need 4' of space for a 4" skyline diffussor. IF you're going to do diffussion anywhere, it would be on that back wall, but I think most people will tell you that you're probably sitting a little too close. Am I remembering wrong guys?


-------------


Unless you're going to hire a professional, start with the basic treatments, fire up your system, takes some measurements with a program like REW, and see how it sounds. Then add more treatment, listen and measure some more, and so forth.


Small rooms are nice (I have to say that because I can't afford a big room), but they have more noticeable room modes. Ethan does a great job explaining it all on the real traps site, but it goes something like...in a smaller room, the first mode occurs at a higher frequency, and at less frequent intervals thereafter, making them more noticeable. You're room measurement ratios match almost perfectly one of the recommended ratios of 1:1.26:1.59, so the modes that you do have should be pretty evenly spaced. Still, I'd plan on supplementing your bass traps with an eq like the Behringer BFD.


----------



## Black Magic

My local SPI is offering a wrapped panel product. They can wrap most of their panels in GOM 701 for a modest fee. For example, 1 panel of 2x4x2" 703 FRK (foil) costs $8.25. The same panel wrapped with GOM 701 with mounting hardware costs $41.72. Discounts start at orders of 100 or more. The panels are wrapped at their Illinois factory, and then shipped to the local store. They need about 3-5 days lead time. If you interested in buying some inexpensive panels, call up your local SPI store and find out if they have a sample panel you can check out.


----------



## yngdiego




> Quote:
> Originally Posted by *eugovector* /forum/post/11884302
> 
> 
> 1. You could give yourself a little breathing room by going superchunk style.
> 
> 
> 2. I think most folks would say that in a room that small, Yes, Every little bit on your front wall will help to keep reflect sound from bouncing back from your primary sound source. I'm no (insert title of one who excels at geometry), but it looks like the angles aren't quite right for a centered seating position, but those sitting on the sides will reap the benefits since that would be a first reflection point for you mains and center. 2" should be fine.
> 
> 
> 3. For the same reasons, I think so. Is you center channel free standing or tucked in an equipment stand? Center channels tend to sound better if they aren't living in a box, but are out in the open, free to breathe.
> 
> 
> 4. Use the mirror trick to find the First Reflection points for your tweeters and mids at all seating locations. If it takes 2 panels on each wall, make sure you cover them all.
> 
> 
> 5. I still haven't put up my ceiling panels, so I can't tell you from personal experience, but at the 2007 HES, Richard Bird of Rives Audio cited a study that found that the ceiling was the most important spot to treat. I'd at least hit the Front Reflection for you 3 front speakers and you main seating location.
> 
> 
> 6. Does the closet have a door? If so, you may actually want to treat the door.
> 
> 
> 7. I think the rule I was quoted by auralex (I should have written it down) was that you need 4' of space for a 4" skyline diffussor. IF you're going to do diffussion anywhere, it would be on that back wall, but I think most people will tell you that you're probably sitting a little too close. Am I remembering wrong guys?
> 
> 
> -------------
> 
> 
> Unless you're going to hire a professional, start with the basic treatments, fire up your system, takes some measurements with a program like REW, and see how it sounds. Then add more treatment, listen and measure some more, and so forth.
> 
> 
> Small rooms are nice (I have to say that because I can't afford a big room), but they have more noticeable room modes. Ethan does a great job explaining it all on the real traps site, but it goes something like...in a smaller room, the first mode occurs at a higher frequency, and at less frequent intervals thereafter, making them more noticeable. You're room measurement ratios match almost perfectly one of the recommended ratios of 1:1.26:1.59, so the modes that you do have should be pretty evenly spaced. Still, I'd plan on supplementing your bass traps with an eq like the Behringer BFD.



Thanks for your input.

1. Does the superchunk style have better/worse absorption properties than a typical "hollow" bass trap? I do agree the extra few inches gained might be very valuable.


2. Not sure what angle you are talking about. If you are referencing the front speaker toe-in, I just took a stab at that in the diagram. They might need more/less, and I'm certainly open to suggestions.


3. The center channel will be on a open suspended glass shelf just under the TV, so it will have lots of breathing room.


4. When using the mirror, should I cover any wall area that I see any part of the speaker, or just from the front grill forward?


6. Closet does currently have sliding doors, but I was thinking of taking them out and putting up a sheer curtain so there was more depth behind the listening positions.


7. If I left the closet doors off, there is significant surface area I could put diffusion and it's 4.5' feet from the listening position.


So sounds like 2" of 703 for everything except the bass traps?


----------



## yngdiego




> Quote:
> Originally Posted by *Black Magic* /forum/post/11888664
> 
> 
> My local SPI is offering a wrapped panel product. They can wrap most of their panels in GOM 701 for a modest fee. For example, 1 panel of 2x4x2" 703 FRK (foil) costs $8.25. The same panel wrapped with GOM 701 with mounting hardware costs $41.72. Discounts start at orders of 100 or more. The panels are wrapped at their Illinois factory, and then shipped to the local store. They need about 3-5 days lead time. If you interested in buying some inexpensive panels, call up your local SPI store and find out if they have a sample panel you can check out.



Pardon my ignorance, but who/what is SPI? Google didn't find much for me. Is there a site we can plug in a zip or city to find local dealers?


----------



## MarkMac




> Quote:
> Originally Posted by *yngdiego* /forum/post/11888803
> 
> 
> Pardon my ignorance, but who/what is SPI? Google didn't find much for me. Is there a site we can plug in a zip or city to find local dealers?


 http://www.spi-co.com/servicecenterdirectory.cfm


----------



## nathan_h




> Quote:
> Originally Posted by *MarkMac* /forum/post/11888845
> 
> http://www.spi-co.com/servicecenterdirectory.cfm



Anyone work with the one near San Francisco? They really didn't seem interested in my business.


----------



## yngdiego

I just called the SF office and talked to Rene. She was actually very helpful and even looked up shipping to San Diego. Her price was $1.50/sqf for Manville 814 and OC703.


----------



## BasementBob

 http://www.bobgolds.com/InsulationContractors.htm


----------



## yngdiego

I was looking at doing OC703 "super chunk" triangles in four corners of my tiny 10x11 HT. I wasn't looking forward to all of the cutting and assembly. I came across the RPG ProCorner system, which is vastly easier to install. Now it's a lot more expensive than just stacking up OC703, but the sound absorption coefficients under 500 Hz are significantly better than what OC publishes for 703.


Are they really that much better, or will 'super chunking' the corners with 17x24" triangles be just as good or better bang for the buck?


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/11910331
> 
> 
> I was looking at doing OC703 "super chunk" triangles in four corners of my tiny 10x11 HT. I wasn't looking forward to all of the cutting and assembly. I came across the RPG ProCorner system, which is vastly easier to install. Now it's a lot more expensive than just stacking up OC703, but the sound absorption coefficients under 500 Hz are significantly better than what OC publishes for 703.
> 
> 
> Are they really that much better, or will 'super chunking' the corners with 17x24" triangles be just as good or better bang for the buck?



There are free spreadsheets around the internet that allow you to input your room dimensions and get a graph of the room nodes. If your room has a "big" problem in the range which the RPG is superior, then perhaps it is worth more. But the SSC traps are darned good for a darned good price.


Wait for the pros, though, to answer!


----------



## Terry Montlick




> Quote:
> Originally Posted by *yngdiego* /forum/post/11910331
> 
> 
> I was looking at doing OC703 "super chunk" triangles in four corners of my tiny 10x11 HT. I wasn't looking forward to all of the cutting and assembly. I came across the RPG ProCorner system, which is vastly easier to install. Now it's a lot more expensive than just stacking up OC703, but the sound absorption coefficients under 500 Hz are significantly better than what OC publishes for 703.
> 
> 
> Are they really that much better, or will 'super chunking' the corners with 17x24" triangles be just as good or better bang for the buck?



One cannot compare the raw material spec (OC703) with a *device* spec. The size and configuration makes all the difference! Check the "SuperChunks" device measurements here:
http://forum.studiotips.com/viewtopic.php?t=536 


Generally, an open-cell foam product will _not_ outperform semirigid fiberglass of the same shape and dimensions.


Regards,

Terry


----------



## jandawil

OK all you acoustic DIYers...a couple of panel questions... I want to make some panels out of 2'X4'X2" thick OC 703 or 705. If I simply wanted to wrap the panels in GOM and mount to my walls, would the 703 be rigid enough for that or should I go 705? Also how would I achieve a beveled edge look to the the panels. Not quite sure how to cut that or what tool(s) would be best? I would think that my table saw would just tear it up. Thanks in advance..


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/11932334
> 
> 
> OK all you acoustic DIYers...a couple of panel questions... I want to make some panels out of 2'X4'X2" thick OC 703 or 705. If I simply wanted to wrap the panels in GOM and mount to my walls, would the 703 be rigid enough for that or should I go 705? Also how would I achieve a beveled edge look to the the panels. Not quite sure how to cut that or what tool(s) would be best? I would think that my table saw would just tear it up. Thanks in advance..



I doubt that either are rigid enough to do what you ask, especially the 703. Most of us make or buy frames, brackets, etc for our fiberglass panels. For cutting and/or sculpting, a cheap electric carving knife works quite well. But again, it is not rigid enough to bevel and have that bevel still be a bevel after stretching cloth over it. Commercial panel makers chemically harden (google it) the edges so that bevels and such are maintained after covering.


----------



## jandawil

OK...than what type of rigid fiberglass is used in the panels you can get from bpape and Sensible Sound Solutions? Here is the link:

http://sensiblesoundsolutions.com/pr...products_id=42 


It appears to be some sort of figid fiberglass with GOM over it. That is what I am going for. Is this a different type of fiberglass panel?


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/11933707
> 
> 
> OK...than what type of rigid fiberglass is used in the panels you can get from bpape and Sensible Sound Solutions? Here is the link:
> 
> http://sensiblesoundsolutions.com/pr...products_id=42
> 
> 
> It appears to be some sort of figid fiberglass with GOM over it. That is what I am going for. Is this a different type of fiberglass panel?



Without speaking for either of the companies you mention, I'll reiterate that any frame-less covered fiberglass panels of 703/705 with a (distinct and well-defined) beveled edge has been chemically hardened to maintain the shape. And it is to be expected that a vendor would not be too specific on how they make their products.


If you follow the link in my sig and go to the pages on building absorbers (starting at pg 16) you will see how to get an edge profile without messing with chemicals. I've applied an eased edge, but could have just as easily beveled it.


----------



## jandawil

Thanks...I'll check it out for sure. I may end up just contacting bpape and having him set me up with some panels that look professionally done. They look great and mine as of now do not.


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/11934066
> 
> 
> Thanks...I'll check it out for sure. I may end up just contacting bpape and having him set me up with some panels that look professionally done. They look great and mine as of now do not.



Reason #1 to buy commercial solutions.


----------



## jandawil

BTW...I saw your panels. Very nicely done, but I just don't want to go to that much trouble.


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/11934187
> 
> 
> BTW...I saw your panels. Very nicely done, but I just don't want to go to that much trouble.



Reason #2 why to buy commercial solutions.


----------



## jandawil

OK...plan B...


The custom panels are just a little too pricey for me. I was thinking of framing up basically a 4'X8' frame on the walls and than placing two layers of Linacoustic in them. Would that work? I am only looking to treat the walls as reflection points to deaden the room a little more. I am not looking to address bass with these. Would this be an effective solution for that? To finish it up I would stretch my left over speaker cloth from Parts Express over it and glue and staple that. Than cover the edge and staples with some finish grade molding.


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/11943371
> 
> 
> OK...plan B...
> 
> 
> The custom panels are just a little too pricey for me.



Reason #1 to DIY absorbers.











> Quote:
> (And) why I was thinking of framing up basically a 4'X8' frame on the walls and than placing two layers of Linacoustic in them. Would that work? I am only looking to treat the walls as reflection points to deaden the room a little more. I am not looking to address bass with these. Would this be an effective solution for that? To finish it up I would stretch my left over speaker cloth from Parts Express over it and glue and staple that. Than cover the edge and staples with some finish grade molding.



At this point you should go to Bob Gold's wonderfully informative absorption coefficients and research the materials typically used for absorbers. I don't know a thing about your room, but unless it's huge, 4x8 absorbers on the walls seems really big. It's really easy to over dampen a room, and more absorption can be added later if needed. And, with that same thinking, if you are already absorbing highs and mids, you should go for as much LF absorption as is practical. As opposed to highs and mids, nearly all rooms (in homes) need bass trapping, so you might as well go low there, too, as separate traps added elsewhere later will also suck out highs and mids.


----------



## Black Magic




> Quote:
> Originally Posted by *jandawil* /forum/post/11943371
> 
> 
> OK...plan B...
> 
> 
> The custom panels are just a little too pricey for me.



The cheapest I've see is from SPI. My local one quoted me $41.72 for a GOM 701 wrapped 703 FRK 2'x4'x2".


----------



## jandawil




> Quote:
> Originally Posted by *Black Magic* /forum/post/11943933
> 
> 
> The cheapest I've see is from SPI. My local one quoted me $41.72 for a GOM 701 wrapped 703 FRK 2'x4'x2".



SPI?? I Googled them and couldn't find anything. Do you have any more info.


Also pepar...I have addressed bass some already but I am not done. I have LOADS of 6lb Roxul mineral wool in the front corners behind the screen wall as well as several 2X4X4" Roxul batts on the floor behind the screen in the corner of the floor and back wall. See pic...









I will also hang a few 4" thick pannels on the back wall spacing away from the wall some to help more with bass. The bass traps I have already added have helped a ton. My room is 16' by 21' so it's decently big. The 4X8 panel would cover maybe 1/4 of the two side walls so that would still leave a lot of wall. If you or others think that is too much I will certainly heed you warnings.


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/0
> 
> 
> 
> Also pepar...I have addressed bass some already but I am not done. I have LOADS of 6lb Roxul mineral wool in the front corners behind the screen wall as well as several 2X4X4" Roxul batts on the floor behind the screen in the corner of the floor and back wall. See pic...
> 
> 
> I will also hang a few 4" thick pannels on the back wall spacing away from the wall some to help more with bass. The bass traps I have already added have helped a ton. My room is 16' by 21' so it's decently big. The 4X8 panel would cover maybe 1/4 of the two side walls so that would still leave a lot of wall. If you or others think that is too much I will certainly heed you warnings.



Again, I would size first reflection point absorbers as small as possible to get the job done. Do the mirror trick, or think of bank shots in pool. Just an observation - from your pic, your right speaker pretty much "sees" only the Roxul to it's left. As such, your first reflection point absorber on the left is already in place. And another observation is that I'd toe-in the speaker so that it aims at the geographical center of the audience.


----------



## myfipie




> Quote:
> Originally Posted by *Black Magic* /forum/post/11943933
> 
> 
> The cheapest I've see is from SPI. My local one quoted me $41.72 for a GOM 701 wrapped 703 FRK 2'x4'x2".




$41.72??????? are you sure on that?? We offer GOM on our GIK242 panel ($54.99) for a $30.00 upcharge and that pretty much just covers the fabric.










Glenn


----------



## myfipie




> Quote:
> I will also hang a few 4" thick pannels on the back wall spacing away from the wall some to help more with bass. The bass traps I have already added have helped a ton. My room is 16' by 21' so it's decently big. The 4X8 panel would cover maybe 1/4 of the two side walls so that would still leave a lot of wall. If you or others think that is too much I will certainly heed you warnings.



That is a great idea but just make sure you build them so the backs do not have a solid piece of wood (or anything solid) covering the back. I saw pepar's build and did see a hard back, which would not work for spacing off the wall.




Glenn


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/11944427
> 
> 
> That is a great idea but just make sure you build them so the backs do not have a solid piece of wood (or anything solid) covering the back. I saw pepar's build and did see a hard back, which would not work for spacing off the wall.



True, Glenn. I didn't want them encroaching into the room any more than necessary, so they are flat-mounted. Also, I was not looking for enhanced LF absorption preferring instead to install bass traps for that.


----------



## jandawil




> Quote:
> Originally Posted by *myfipie* /forum/post/11944427
> 
> 
> That is a great idea but just make sure you build them so the backs do not have a solid piece of wood (or anything solid) covering the back. I saw pepar's build and did see a hard back, which would not work for spacing off the wall.
> 
> 
> 
> 
> Glenn



That was my plan..


pepar...why I was thinking 4X8 because some very good HT's here cover the entire lower half of their wall in Linacoustic and GOM. My coverage would be less than that. Not sure how much is "too dead".


----------



## jandawil




> Quote:
> Originally Posted by *myfipie* /forum/post/11944384
> 
> 
> $41.72??????? are you sure on that?? We offer GOM on our GIK242 panel ($54.99) for a $30.00 upcharge and that pretty much just covers the fabric.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Glenn



Hey myfipe....I just went to your website and saw your panels...what do you use rather than GOM. They look pretty good.


----------



## pepar




> Quote:
> Originally Posted by *jandawil* /forum/post/11944895
> 
> 
> That was my plan..
> 
> 
> pepar...why I was thinking 4X8 because some very good HT's here cover the entire lower half of their wall in Linacoustic and GOM. My coverage would be less than that. Not sure how much is "too dead".



I have the lower half of my room covered with "wall" carpet, the cavity behind my false wall lined with 2" Linacoustic and strategically sized/placed absorbers of 2" OC SelectSound Black and I think my room is too dead. If I were building it today, I'd skip the carpet around the perimeter and keep the carpet on the front right and left walls for light control. YMMV.


----------



## bpape

If you're going to DIY and want a beveled edge, a perimeter frame is almost mandatory. For frameless, it's OC705. The 703 simply will not hold up to getting the cloth stretched tight enough to look decent. As was stated earlier, to treat the edges with a detail, they are chemically resin hardened to hold that shape and around the perimeter to withstand the cloth stretching without crushing.


In all honesty, while a bit more work, I'd rather see you do 3 2'x4'x2" panels with a bit of space between them. It's not all about coverage, it's about getting a good distribution of the absorbtion also.


Bryan


----------



## jandawil




> Quote:
> Originally Posted by *bpape* /forum/post/11988166
> 
> 
> If you're going to DIY and want a beveled edge, a perimeter frame is almost mandatory. For frameless, it's OC705. The 703 simply will not hold up to getting the cloth stretched tight enough to look decent. As was stated earlier, to treat the edges with a detail, they are chemically resin hardened to hold that shape and around the perimeter to withstand the cloth stretching without crushing.
> 
> 
> In all honesty, while a bit more work, I'd rather see you do 3 2'x4'x2" panels with a bit of space between them. It's not all about coverage, it's about getting a good distribution of the absorbtion also.
> 
> 
> Bryan



Would 1" linacoutic work for that. I was thinking of building 1" frames and using the linacousic inside. What would be the difference practically speaking between 2" 703 and linacoustic. Obviously there would be no bass or broadband absorbtion, but for early reflections would that work. I am just looking to deaden the room a bit more.


----------



## bpape

I'd need to know what else is in the room to know what's appropriate. The 2" will extend significantly lower - well into the male vocal range (low hundreds). The idea is to keep the room balanced. Just deadening highs more may not be preferable without some lower absorbtion also depending on what the balance is right now.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/11997515
> 
> 
> I'd need to know what else is in the room to know what's appropriate. The 2" will extend significantly lower - well into the male vocal range (low hundreds). The idea is to keep the room balanced. Just deadening highs more may not be preferable without some lower absorbtion also depending on what the balance is right now.
> 
> 
> Bryan



As someone who has installed a lot of wall carpet in my room and now has a dead, but boomy room, I can attest to this. Use the 2".


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/11998567
> 
> 
> As someone who has installed a lot of wall carpet in my room and now has a dead, but boomy room, I can attest to this. Use the 2".



You have 7,142 posts here yet you put carpet on your walls anyway?


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/12001261
> 
> 
> You have 7,142 posts here yet you put carpet on your walls anyway?



I know exactly what you mean, Ethan, . . . NOW. But that was 7000 posts ago.










I can at least serve as a bad example.


----------



## Justletmein

I see some walls of the theaters in here completely covered in GOM ( or equivalent ) with acoustic insulation underneath ... wont these rooms be referred to as " dead "


I am in the framing/rough-in stage of my theater now and am a bit unclear as to what direction to take



I can add corner traps at the front and was was considering linocoustic ( or equivalent ) on the walls/ceiling ... this would be my preference as I can then use fabric/trim only for the finishing of the room


Room is 23'5" X 14'5" X 8'6"


Thanks for any advice


----------



## pepar




> Quote:
> Originally Posted by *Justletmein* /forum/post/12005605
> 
> 
> I see some walls of the theaters in here completely covered in GOM ( or equivalent ) with acoustic insulation underneath ... wont these rooms be referred to as " dead "?



Are you certain that underneath *all* of the GOM is insulation? There are panelized systems of acoustical treatments that, when installed, give the appearance of entirely GOM'd walls. These panels are either absorbers, diffusors or reflectors, but all look the same. Could this be what you saw?


----------



## darrellh44

Are there any guidelines for adding soffits for bass absorption (dimensions, amount/type of aborption material, etc)?


My room is 26' x 19.5' x 9.2'. I would like to add soffits all around that come out 2' from the walls and drop about 10" from the ceiling. My plan is fill the space by stacking 703 or 705 panels with FRK facing on the outer surfaces to minimize high frequency absorption. Should I stack as many of the heavier panels as I can, or is there a point where the diminishing returns aren't worth the added cost?


Thanks,

Darrell


----------



## Justletmein




> Quote:
> Originally Posted by *pepar* /forum/post/12005863
> 
> 
> Are you certain that underneath *all* of the GOM is insulation? There are panelized systems of acoustical treatments that, when installed, give the appearance of entirely GOM'd walls. These panels are either absorbers, diffusors or reflectors, but all look the same. Could this be what you saw?




Well then lets not dispute whether ALL the walls have acoustic absorption and take a look at my future theater room using the first reflection program from this forum


The room will have a 7.1 surround system ... what would be the suggestion for acoustic absorption/diffusors/reflectors in this case ? ( also assuming all walls/ceilings covered with a GOM type fabric )


----------



## bpape

When calculating the reflections, don't forget the 2nd row. Not only is this another set of reflections off the side walls in the length dimension, but if it's on a riser, it will also have that set up higher than the first set due to higher seated ear position in the rear.


Based on that drawing, the acoustic center of those speakers appears to be very low in comparison to the screen image.


Bryan


----------



## Justletmein




> Quote:
> Originally Posted by *bpape* /forum/post/12007890
> 
> 
> When calculating the reflections, don't forget the 2nd row. Not only is this another set of reflections off the side walls in the length dimension, but if it's on a riser, it will also have that set up higher than the first set due to higher seated ear position in the rear.
> 
> 
> Based on that drawing, the acoustic center of those speakers appears to be very low in comparison to the screen image.
> 
> 
> Bryan



It maybe a little difficult to see in that picture but there are 2 rows of seats illustrated there in green.


Also I was considering a stage which would raise the height of the main speakers


However ... assuming it all remained as is ... from what I have read using linocoustic under the GOM in those early reflection points


what would you suggest to use in the areas that are not highlighted as a first reflection point ? cotton batting ?


----------



## pepar




> Quote:
> Originally Posted by *Justletmein* /forum/post/12006826
> 
> 
> Well then lets not dispute whether ALL the walls have acoustic absorption and take a look at my future theater room using the first reflection program from this forum
> 
> 
> The room will have a 7.1 surround system ... what would be the suggestion for acoustic absorption/diffusors/reflectors in this case ? ( also assuming all walls/ceilings covered with a GOM type fabric )



Missing from your way cool model is the reflections from the back wall. The biggest difference in my room occurred when I added the rear wall absorber. There's some disagreement about lateral reflections, but I'm still confident about recommending the rear wall and front ceiling with 2" 703 (or equivalent). And placing a heavy rug in the front floor area.


----------



## Justletmein

Actually I do have those reflections in the model ( just cant see from that angle







) they occur mostly below chair rail height


----------



## bpape

What you do in the areas not showing reflections depends on what else is done in the room, the room construction, number and type of seating, number of people, etc. All of those things act on the decay in the room. I'm personally not a big fan of batting. It looks nice but it offers only high frequency absorbtion and filling all the rest of the wall surface with that IMO skews the decay curve to being too dead up high.


Bryan


----------



## nathan_h




> Quote:
> Originally Posted by *darrellh44* /forum/post/12006626
> 
> 
> My plan is fill the space by stacking 703 or 705 panels with FRK facing on the outer surfaces to minimize high frequency absorption. Should I stack as many of the heavier panels as I can, or is there a point where the diminishing returns aren't worth the added cost?



In general, more is better.


What is FRK facing?


----------



## jchretien4

Finishing drywall in small home theater; intend to put 1" insul-shield on the front and on the bottom 44" of the sides, with batting above. I want to cover it all with fabric, probably a deep red or burgundy.


Any recommendations for fabric and a fabric source for this purpose?


Is GOM fabric appropriate and cost-effective for this purpose?


Thanks -


jchretien4


----------



## Justletmein




> Quote:
> Originally Posted by *bpape* /forum/post/12018662
> 
> 
> What you do in the areas not showing reflections depends on what else is done in the room, the room construction, number and type of seating, number of people, etc. All of those things act on the decay in the room. I'm personally not a big fan of batting. It looks nice but it offers only high frequency absorbtion and filling all the rest of the wall surface with that IMO skews the decay curve to being too dead up high.
> 
> 
> Bryan




Although not shown in that diagram ... I want to build a enclosure for the sub and center channel up front and also enclose the side speakers with Roxul in the front corners ( behind the side speakers and also behind the sub/center channel )


There are 2 rows of 4 Coaster studio seats 12' and 18' from the screen and the room size is 23'5" X 14'5" X 8'6" ... resilient channel on walls and ceiling with double drywall , 136" Carada BW 237:1 Scope screen and a HD80


all the other walls/ceiling I would like covered in fabric


It will be a 7.1 Axiom speaker system ( 2 X M80 mains, 1 X VP150 center, 2 X QS8 surround, 2 X QS8 surround rears & EP600 sub )


so I assume using 1" linocoustic on those first reflections would work but if batting would deaden the sound too much then what could I use in lieu of batting to keep the areas without linocoustic the same 1" depth so it all looks smooth when covered in fabric ?


----------



## darrellh44




> Quote:
> Originally Posted by *nathan_h* /forum/post/12018735
> 
> 
> In general, more is better.
> 
> 
> What is FRK facing?



FRK is a foil like covering on one side of the panel that reflects higher frequencies but still allows low frequencies to be absorbed. Compare the absorption coefficients for same density and thickness panels on this webpage:

http://www.bobgolds.com/AbsorptionCoefficients.htm 


-Darrell


----------



## nathan_h

Interesting. I guess I can see why one would worry about too much high frequency absorption.


But I assume you will have to cover the FRK with something else? Fabric?


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/12031301
> 
> 
> Interesting. I guess I can see why one would worry about too much high frequency absorption.
> 
> 
> But I assume you will have to cover the FRK with something else? Fabric?



Well, yes, and it must be acoustically transparent so that the sound can get through it to be absorbed.


----------



## Justletmein

So is that what you guys are using in areas outside of first reflection points is a FRK faced insulation ?


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/12031376
> 
> 
> Well, yes, and it must be acoustically transparent so that the sound can get through it to be absorbed.



Do you mean acoustically permeable? Transparent would be important covering a speaker, but covering a treatment it wouldn't matter so much whether it is absorbing some and transmitting some through to the insulation beneath, right?


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/12036628
> 
> 
> Do you mean acoustically permeable? Transparent would be important covering a speaker, but covering a treatment it wouldn't matter so much whether it is absorbing some and transmitting some through to the insulation beneath, right?



This has come up before and perhaps it's semantical, but to be precise, whether the sound is absorbed by the covering itself or passed through for absorption by the 'glass underneath doesn't matter. So the cloth covering really only needs to _not be reflective_. Personally, though, the GOM FR701 Style 2100 I used to cover my false wall - with speakers behind it - is also covering my absorbers. It was just simpler that way.


----------



## bpape

FSK facing is NOT used on panels where you're trying to address first and early reflections. You want those to absorb all the way up.


The FSK is useful when you need to add some additional bass/low mid absorbtion without overdoing the highs. Rear corners, soffits, LOW lower portions of side walls, etc. are places where this can be effective.


Bryan


----------



## Justletmein

Here is a better shot of the first reflections using the first reflection program from jeffreylebowski

http://www.avsforum.com/avs-vb/showt...ection+program 


no suggestions as to what to cover the remaining walls ? ... it sounds from Bryan's response that a FSK facing may be used in the areas outside the first reflection points but possibly not ALL those surfaces ... is that correct ? ... should I wait till the room is complete to determine what to cover the remaining walls ?


----------



## pepar




> Quote:
> Originally Posted by *Justletmein* /forum/post/12038115
> 
> 
> Here is a better shot of the first reflections using the first reflection program from jeffreylebowski
> 
> 
> no suggestions as to what to cover the remaining walls ? ... it sounds from Bryan's response that a FSK facing may be used in the areas outside the first reflection points but possibly not ALL those surfaces ... is that correct ? ... should I wait till the room is complete to determine what to cover the remaining walls ?



Here is what I would do based on my own experience. (Visit my link.) First, I would cover, as precisely as possible, the first reflection points of the three front speakers. I would use 2" of OC 703 (or equiv.) Next I would install bass traps Studio Superchunks-style. The more two-surface junctions you can do, the better. Aesthetics will no doubt be a limiting factor, but all four corners would be good - floor to ceiling. And then I would listen to the room/system. If you have the know-how, use one of the freeware/shareware programs, like Room EQ Wizard, and a mic and do some testing. From this you can decide whether or not you need any further treatments.


If nothing else, my stepping up to post this may cause the _real_ acoustical experts to chime in!


----------



## Justletmein




> Quote:
> Originally Posted by *pepar* /forum/post/12038484
> 
> 
> Here is what I would do based on my own experience. (Visit my link.) First, I would cover, as precisely as possible, the first reflection points of the three front speakers. I would use 2" of OC 703 (or equiv.) Next I would install bass traps Studio Superchunks-style. The more two-surface junctions you can do, the better. Aesthetics will no doubt be a limiting factor, but all four corners would be good - floor to ceiling. And then I would listen to the room/system. If you have the know-how, use one of the freeware/shareware programs, like Room EQ Wizard, and a mic and do some testing. From this you can decide whether or not you need any further treatments.
> 
> 
> If nothing else, my stepping up to post this may cause the _real_ acoustical experts to chime in!



All good advice ... thanks ... I did d/l the wizard proggy a little while back now that I think about it







... I will plug away at finishing the room/basement and then revisit this topic once I can test the results


----------



## Texas Tuck

I did a search on Acoustiblok in this forum and I really didnt find the good or bad. Anyone ever use it? Worth the time and trouble? Their demo at CEDIA Denver was impressive.


We are considering being a dealer and installer for them. Of course, I like others opinions here first.


THanks!


----------



## pepar

Just a thought, Justletmein, that your chairs and listeners will block the sound getting directly to the rear wall . . .


----------



## pepar




> Quote:
> Originally Posted by *Justletmein* /forum/post/12041633
> 
> 
> All good advice ... thanks ... I did d/l the wizard proggy a little while back now that I think about it
> 
> 
> 
> 
> 
> 
> 
> ... I will plug away at finishing the room/basement and then revisit this topic once I can test the results



I think your take away here should be that it's very easy to over-dampen a small room, and care needs to be taken to absorb sound as _evenly_ as possible at all frequencies.


----------



## bpape

Exactly. You're not going to get an exact answer without doing a full analysis of the space. For the basics:


Front corners - broadband bass control.


Front wall - dead broadband 100% coverage.


Side walls - reflection coverage.


Balance - depends on desired room finish and a ton of other options. You can use some online calculators to determine what your target decay curve SHOULD be for your usage and then use REW as a free tool to measure what you actually have.


The other option is to hire someone to do the design for you.


Bryan


----------



## zmisst




> Quote:
> Originally Posted by *bpape* /forum/post/12043939
> 
> 
> Front wall - dead broadband 100% coverage.



I think this must have been discussed somewhere but I haven't come across it.


If a front wall is otherwise covered with all absorption panels other than the screen, how much difference is there between:


1) AT screen with absorption behind it

2) non AT screen with absorption behind it (I presume higher freqs would tend to reflect off the screen, but mid-lower freqs would be absorbed).

3) non AT screen mounted traditionally against the drywall


And assume an average HT front wall is 14 x 8 = 112 sq feet; and an average 106" screen @ 4.33 x 7.66 = 33.22 sq feet. So the screen makes up 30% of the front wall.


It seems than 1) would be ideal, but how much worse is 2) or 3)?


----------



## bpape

It all depends on your situation. I don't mean to sound like a broken record but every room and every situation is different.


Most non AT screens have a gap behind them that will allow maybe some 1" absorbtion even when mounted flush frame to wall. Yes - the highs will still reflect (nothing you can do about this) - but - the mids (vocal range) will still be absorbed and help to focus things to the screen even more.


Bryan


----------



## zmisst

Interesting. I forgot that I had previously read another view which was:


"If the screen is not micro-perforated, then it's not worth putting fiberglass behind. The solid screen would reflect frequencies above a few hundred hertz. But below this frequency, the absorption ability of even 3 inches of fiberglass falls off significantly. So you'd end up with an absorber peaking at a few hundred hertz."


from this same thread at: http://www.avsforum.com/avs-vb/showt...89#post5359089 


Presumably creating a hole in the mid freqs that pass the screen and are absorbed behind it? But it's just 30% of the wall, and probably some high freqs would pass the screen and be absorbed?


Anyone have any direct experience with trying it both ways? Absorber behind a non AT screen and not? Or replacing a non AT screen with an AT screen?


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/12057946
> 
> 
> Interesting. I forgot that I had previously read another view which was:
> 
> 
> "If the screen is not micro-perforated, then it's not worth putting fiberglass behind. The solid screen would reflect frequencies above a few hundred hertz. But below this frequency, the absorption ability of even 3 inches of fiberglass falls off significantly. So you'd end up with an absorber peaking at a few hundred hertz."
> 
> 
> from this same thread at: http://www.avsforum.com/avs-vb/showt...89#post5359089
> 
> 
> Presumably creating a hole in the mid freqs that pass the screen and are absorbed behind it? But it's just 30% of the wall, and probably some high freqs would pass the screen and be absorbed?
> 
> 
> Anyone have any direct experience with trying it both ways? Absorber behind a non AT screen and not? Or replacing a non AT screen with an AT screen?



I think that there are two things going on here. First, that some recommend fully treating the front wall a la the Live End Dead End philosophy. And second, that the cavity behind a false wall and AT screen should be fully treated so as to reduce/eliminate comb filtering. I happen to follow both myself.


edit: I even have sculpted a 2" 'glass "mask" for the center speaker.


----------



## BasementBob

pepar:


I don't know if treating the front wall qualifies for "Live End Dead End".

a) what if one treats the back wall too? Is that DeadEndDeadEnd.

b) the reason for treating the front wall is that with 7.1 we can get a lot of artificial ambiance from multiple speakers, but for films we're more paranoid about imaging (I'm not suggesting anechoic chambers).

c) the front wall treatment usually tends to be a bit thin (HF absorption) for what I think of as "Dead End", at least from what I remember of Don and Carolyn Davis's LEDE invention. I think they really wanted to kill an end (more than a wall). As opposed to Non-Environment where they want to kill 3 walls and 1 ceiling -- which I believe is probably not a good idea for home theatre.



> Quote:
> And second, that the cavity behind a false wall and AT screen should be fully treated so as to reduce/eliminate comb filtering.



I did some measurements of that somewhere....
http://www.bobgolds.com/SmX720/20060708/home.htm 



> Quote:
> I even have sculpted a 2" 'glass "mask" for the center speaker



Did you measure what that did to your speaker? I found that it turned my very nice speaker into a not so nice one. See "The rockwool baffel" on the same page.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/0
> 
> 
> 
> Did you measure what . . (the 2" glass mask) . . did to your speaker? I found that it turned my very nice speaker into a not so nice one. See "The rockwool baffel" on the same page.



I really meant sculpted. The holes around the drivers were beveled at a 45 degree angle so the drivers could "see" a very wide angle. Test it? No, I didn't, but I took the precaution I just mentioned. I applied the mask at the recommendation of John Dahl.


----------



## BasementBob

pepar: sorry. link repaired.


BTW, when I put together my living room plasma setup, I elected not to have the edges of my speakers near anything. Seemed more idiot proof.
http://www.bobgolds.com/LivingRoomPl...ction/home.htm 

YMMV - especially with speakers behind an acoustically transparent screen.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/12059698
> 
> 
> pepar: sorry. link repaired.
> 
> 
> BTW, when I put together my living room plasma setup, I elected not to have the edges of my speakers near anything. Seemed more idiot proof.
> http://www.bobgolds.com/LivingRoomPl...ction/home.htm
> 
> YMMV - especially with speakers behind an acoustically transparent screen.



Thanks, I'm there now . .


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/12059698
> 
> 
> pepar: sorry. link repaired.
> 
> 
> BTW, when I put together my living room plasma setup, I elected not to have the edges of my speakers near anything. Seemed more idiot proof.
> http://www.bobgolds.com/LivingRoomPl...ction/home.htm
> 
> YMMV - especially with speakers behind an acoustically transparent screen.



Was there a "conclusion" to your AT screen distance from speaker test? It looked like the greater the distance, the less there was an effect on response.


BTW, here's my sculpted 'glass mask.


----------



## BasementBob

pepar:



> Quote:
> Was there a "conclusion" to your AT screen distance from speaker test? It looked like the greater the distance, the less there was an effect on response.



True, but there's a diminishing returns. I don't remember the officially accepted distance, but 6" to 8" rings a vague bell. (i.e. speaker distance behind AT screen)

The discussion, and conclusions, were over at Rubin's SMX forum.


----------



## agbrander

Hi all


I am setting up a dedicated HT space in my basement, however it is a rental so I cannot do too much modification. My front wall has a window behind the screen, and also a heavy metal-framed exterior door to the left of the screen. I am looking for advice on proper acoustical treatment.


Kit and dimensions first:


I am using an Onkyo 705 receiver to power an Aperion 5.1 setup with the 10" Sub, 533-VAC center, two 533-T towers, and a pair of 422-LR sats for surround. For picture I am projecting a Sharp XVZ-12000 MKII onto a 106" Greywolf.


My screen wall is 17'W x 8'H. The seating position is about 15' from the wall, on a 10' wide couch.. The two side walls are blank. Behind the seating there is another 8' of open space then the basement narrows to a 20' long 6' wide corridor. There is no rear wall as such, because there are wooden slatted doors to one side of the corridor and a large metal spiral staircase on the other side


The front wall contains a 7'H x 3'W door that is set 18" in from the left wall, and a 5' W x 42" H window 1' in from the door and 1' down from the ceiling; the window is recessed 8".


Because of the door placement, my screen is 4" off-center on the front wall, and the towers will need to at least 3' in from the front wall in order to allow the door to be opened. The screen (not AT) will cover the window completely.


The center will be be mounted on a 18" stand about 1' away from the screen wall, and the sats will most likely be on stands.



THANKS TO ANYONE WHO HAS WADED THROUGH ALL THAT!!! NOW TO THE QUESTIONS!


I have read up on acoustical treatment, but have never worked with it. My questions are:


1) I hear it is important to treat the screen wall. I am concerned due to the door and window that it will be harder to treat, and cause weird sound artifacts. Will it be enough to put a fabric curtain on the window and the door's glass panel, or should I be treating the rest of the wall with foam? Do I not even need to worry about treating the window as it is behind the screen and I have no rear wall reflecting anything?


If I don't want to cover the whole wall with foam because of aesthetic issues (my wife's more than mine), does it make sense particularly to treat behind the speakers??


2) What is the minimum suggested treatment for the side walls? Floor to ear-height, 2 foot wide covering on the primary reflection points for each of the 3 speakers on each wall? Or is that total overkill and I should set up the system and see what the issues are before I order any foam?


3) Given that my towers will be a few feet in diagonally from the room corners, does having corner bass absorbers help?


(The foam I was looking at was the 2" wedge foam from foambymail)


Thanks for comments on these questions, and any pointers that could suggest a different way of looking at this... I am here to learn.


Thanks


Alex


----------



## bpape

In general, foam is an inferior product. The Foam By Mail is pretty worthless. They've been caught putting up cheap products for sale and then copying Auralex's specs to their site and touting them as their tested results. I'd stay way away from any company with those kinds of business ethics.


The front wall should be treated fully. Not sure what you mean about no rear wall reflecting.


Side walls need to be addressed minimally for early reflections and then again to finish bringing general decay times into line for the room volume and usage.


Bryan


----------



## agbrander

Thanks bpape. Will steer clear of FBM... what should i use instead that works but is cheap? In terms of fully treating the front wall, with a big door and a recessed window does that mean treating the wall around those, or should i be concentrating on treating those spaces?


i said no rear wall reflecting bc there is to all intents and purposes no single rear wall to the space - a third of the wall is slatted wooden doors at 25' away that will diffuse sound, a third is 50' away at the end of a corridor and a third is an irregularly shaped large spiral staircase at 25' with no flat surface.


Thanks again


Alex



> Quote:
> Originally Posted by *bpape* /forum/post/12066595
> 
> 
> In general, foam is an inferior product. The Foam By Mail is pretty worthless. They've been caught putting up cheap products for sale and then copying Auralex's specs to their site and touting them as their tested results. I'd stay way away from any company with those kinds of business ethics.
> 
> 
> The front wall should be treated fully. Not sure what you mean about no rear wall reflecting.
> 
> 
> Side walls need to be addressed minimally for early reflections and then again to finish bringing general decay times into line for the room volume and usage.
> 
> 
> Bryan


----------



## agbrander

Just so I understand... would you say don't use even Auralex foam? Or just steer clear of FBM?



> Quote:
> Originally Posted by *bpape* /forum/post/12066595
> 
> 
> In general, foam is an inferior product. The Foam By Mail is pretty worthless. They've been caught putting up cheap products for sale and then copying Auralex's specs
> 
> 
> Bryan


----------



## eugovector

Auralex is good stuff, FBM is not, Fiberglass is better than both.


A picture is worth a thousand words, and as much as it will pain you, you should probably start at the beginning of this thread.


I have a rental, non-dedicated space, and for $300, was able to DIY 12 2x4 panels that hang to the wall with a french cleat system, 2 3/8" holes in the wall for each. A little spackle and paint when I move out, and voila.


1) I would be good to see a picture. You may opt to reverse your room by 180 degrees to have the window and door at your back. Curtain both with light blocking fabric.


2) You can accomplish a lot with 2x4 panels, you don't need to go all the way to the floor, assuming that you have other absorption in the room (carpet or rugs, soft furniture).


3) Ethan will tell you that you'll need bass traps. The rest of us would probably say that you'll want bass traps


----------



## bpape

Eugo hit it. IF you must do foam, use Auralex. However, for the same or less money, you can use OC703 or an equivalent or even cheaper is mineral wool (though a PITA to work with IMO) both of which inch for inch are a better solution.


Cover as much of that wall as you can. User THICK curtains over the window. A door is a door - not much you can do but put a panel on it.


Bryan


----------



## SteveMo

I was going to go with some Auralex bass traps in the corners of my room. I have done testing and thats where the problems seem to be. In the rear of the room I do not hear a breeze going by like I do standing in the front of the room. That may have something to do with the bass traps I added to the rear speakers area by adding holes to it lining it with some fiberglass insulation and covering it in the same outdoor carpet as the rest of the room. I have my sub pointing at my screen across the room and I plan on putting a 2nd sub under my center channel. I was thinking some framed fiberglass and then some cloth at the store would help tame the midrange and possibly address some of the standing waves I have as a result of the big woofers in my mains I think. I would also use those as diffusers and the same for the rear row in my room. I am supposed to do something to the front of the room but I have not figured out what exactly. I have been reading and testing the room as fast as I can. I think I may have around $1000.00 or so to spend. If anyplace took payments for their products over a time period that would also help. I had it picked out but it has been so long in my build I lost the kit I had picked out. There are more details in the theater build thread and specifically on this page. I have some wood working experience not much though. I have a heated garage to work in and I could rent tools if I needed. Whatever works best without being a waste of money is what I am interested in. If anything is unclear or if I am going to fast just let me know.


----------



## bpape

For $1k budget and DIY skills, you can go a LONG way toward a total room treatment solution.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/12080151
> 
> 
> For $1k budget and DIY skills, you can go a LONG way toward a total room treatment solution.



Indeed, DIY is a huge "force multiplier."


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/12080220
> 
> 
> Indeed, DIY is a huge "force multiplier."



Yes, I bought 256sqft of 2" 3Lb Fibre glass insulation, plus a crapload of GOM fabric for about $700. That's enough for 4 super chunk corner bass traps, and several wall/ceiling panels.


Thrown in a turkey carving knife, Velcro, a little molding, Roto fasteners, and I'm set!


----------



## SteveMo

I can only fit 12" diagonal across the corners of the room. Do you recommend something on the top of the sides of the room also then? Is treating only a partial amount of the front wall ok? It is important to mention that my ceiling acts like diffusers on the sides and that the rest is also PVC ceiling tile but it is not as rigid.


Eidt: Or rather they are more rigid type of an abortion of lower frequencies I mean. Can I put carpet on the front wall to make it soft with some padding?


----------



## SteveMo




> Quote:
> Originally Posted by *yngdiego* /forum/post/12080450
> 
> 
> Yes, I bought 256sqft of 2" 3Lb Fibre glass insulation, plus a crapload of GOM fabric for about $700. That's enough for 4 super chunk corner bass traps, and several wall/ceiling panels.
> 
> 
> Thrown in a turkey carving knife, Velcro, a little molding, Roto fasteners, and I'm set!



Velcro? Where?


----------



## SteveMo

I see... for the panels to the wall you are saying. I agree it looks safer that way. Alright thank you I think I got the list now.


Edit: There was some miscommunication on my end. I should have taken more time making the list. I'm not really interested in building one panel a week. Save $ up then build. I see a whole room treatment at one time being best so I will wait.


----------



## bpape

The 12" diagonal will still help - though I'd build them solid as opposed to straddling some 4". Just remember that not only are you losing surface area, but you're also losing depth of the absorber (ability to absorb deeper frequencies) so additional treatments elsewhere can make up for part but not the other.


Bryan


----------



## dunragit

Do I still need to treat the front wall if my mains will be away from the wall?


The way I understand it, I don't need to?


----------



## dunragit




> Quote:
> Originally Posted by *dunragit* /forum/post/12117659
> 
> 
> Do I still need to treat the front wall if my mains will be away from the wall?
> 
> 
> The way I understand it, I don't need to?



Nevermind I figured it out.


----------



## SteveMo

Thank you Bryan I will look at some columns today.


----------



## SteveMo




> Quote:
> Originally Posted by *bpape* /forum/post/12109257
> 
> 
> The 12" diagonal will still help - though I'd build them solid as opposed to straddling some 4". Just remember that not only are you losing surface area, but you're also losing depth of the absorber (ability to absorb deeper frequencies) so additional treatments elsewhere can make up for part but not the other.
> 
> 
> Bryan



Could you specifically describe for us what material needs to be in the corners please?


Edit: Never mind we understand what you mean about solid. I argued with the crew to make them solid before but they would not go to get more insulation.


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/12118861
> 
> 
> Could you specifically describe for us what material needs to be in the corners please?



Owens Corning 703, or equivalent.


----------



## eugovector




> Quote:
> Originally Posted by *SteveMo* /forum/post/12118861
> 
> 
> Could you specifically describe for us what material needs to be in the corners please?



I'd bet money that this is mentioned a dozen times in this thread, but you need mineral wool or rigid fiberglass. OC703 is the most common choice.


Look for a material with high numbers in the 125HZ column here: http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/12118965
> 
> 
> I'd bet money that this is mentioned a dozen times in this thread, but you need mineral wool or rigid fiberglass.



You'll not find anyone to give you odds on that.


----------



## SteveMo

Sorry. See the edit above. I think Bryan thought I meant to have my bass traps partially filled.


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/12118861
> 
> 
> Could you specifically describe for us what material needs to be in the corners please?
> 
> 
> Edit: Never mind we understand what you mean about solid. I argued with the crew to make them solid before but they would not go to get more insulation.



Did "the crew" not work for you?


----------



## agbrander

I am looking to use Roxul 60 for my bass traps. The guy I spoke to at the supplier said that some people are chopping the Roxul 60 into 2' right triangles and stacking them floor to ceiling rather than just fixing them across the corner in order to build the bass traps.


Three questions for the esteemed panelists ;-)


1) Cost and time aside, does it make sense to do this? Will a corner with essentially 14" deep of absorbing material be more effective as a trap than 4" deep with air behind? (This may seem like a silly question but this is not always intuitive, and I want someone here to confirm)


2) The Roxul is pretty cheap so if its worth it I don't mind the addnl cost - but I have heard it is a pain to cut - any tips or comments?


3) Finally, is the Roxul really a good alternative to the OC 705 for this purpose?



Thanks and have a nice day!


Alex


----------



## yngdiego




> Quote:
> Originally Posted by *agbrander* /forum/post/12131422
> 
> 
> 
> 1) Cost and time aside, does it make sense to do this? Will a corner with essentially 14" deep of absorbing material be more effective as a trap than 4" deep with air behind? (This may seem like a silly question but this is not always intuitive, and I want someone here to confirm)
> 
> Alex



I'm no acoustical expert, but this last week I just got done installing two "super chunk" bass traps using OC703 material. Each triangle is 17" along the wall and a 24" room-facing side. I was told this was a better solution than 4" of 2'x8' material stacked in the corner with air behind.


----------



## agbrander

To be clear - I have a sub-$2k system, with an Onkyo-705 powering an Aperion S10 subwoofer - enough to make a little noise, but not huge or high-end... so please comment with that in mind when answering the "is it worth it" question




> Quote:
> Originally Posted by *agbrander* /forum/post/12131422
> 
> 
> I am looking to use Roxul 60 for my bass traps. The guy I spoke to at the supplier said that some people are chopping the Roxul 60 into 2' right triangles and stacking them floor to ceiling rather than just fixing them across the corner in order to build the bass traps.
> 
> 
> Three questions for the esteemed panelists ;-)
> 
> 
> 1) Cost and time aside, does it make sense to do this? Will a corner with essentially 14" deep of absorbing material be more effective as a trap than 4" deep with air behind? (This may seem like a silly question but this is not always intuitive, and I want someone here to confirm)
> 
> 
> 2) The Roxul is pretty cheap so if its worth it I don't mind the addnl cost - but I have heard it is a pain to cut - any tips or comments?
> 
> 
> 3) Finally, is the Roxul really a good alternative to the OC 705 for this purpose?
> 
> 
> 
> Thanks and have a nice day!
> 
> 
> Alex


----------



## uncle phil




> Quote:
> Originally Posted by *agbrander* /forum/post/12131422
> 
> 
> I am looking to use Roxul 60 for my bass traps. The guy I spoke to at the supplier said that some people are chopping the Roxul 60 into 2' right triangles and stacking them floor to ceiling rather than just fixing them across the corner in order to build the bass traps.
> 
> 
> Three questions for the esteemed panelists ;-)
> 
> 
> 1) Cost and time aside, does it make sense to do this? Will a corner with essentially 14" deep of absorbing material be more effective as a trap than 4" deep with air behind? (This may seem like a silly question but this is not always intuitive, and I want someone here to confirm)
> 
> 
> 2) The Roxul is pretty cheap so if its worth it I don't mind the addnl cost - but I have heard it is a pain to cut - any tips or comments?
> 
> 
> 3) Finally, is the Roxul really a good alternative to the OC 705 for this purpose?
> 
> 
> 
> Thanks and have a nice day!
> 
> 
> Alex



I'm using also Roxul 60 for my panels, for bass trap I cut 17" right triangle and stack them from floor to ceiling. cover it with polyester batting and panel. I use hack saw blade to cut it.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12131741
> 
> 
> I'm no acoustical expert, but this last week I just got done installing two "super chunk" bass traps using OC703 material. Each triangle is 17" along the wall and a 24" room-facing side. I was told this was a better solution than 4" of 2'x8' material stacked in the corner with air behind.



That is what the test data shows. What difference has it made in the sound?


----------



## Ethan Winer




> Quote:
> Originally Posted by *agbrander* /forum/post/12131924
> 
> 
> To be clear - I have a sub-$2k system, with an Onkyo-705 powering an Aperion S10 subwoofer - enough to make a little noise, but not huge or high-end... so please comment with that in mind when answering the "is it worth it" question



Yes, it's worth it! I have two state of the art systems in my house, and both systems added together cost _way_ less than many audiophiles drop on their turntable alone. What makes my system state of the art is extensive room treatment. Well, that and professional quality loudspeakers.


Bass traps and other acoustic treatment are not a silly audiophile tweak that can be appreciated only with $40k apiece loudspeakers.










--Ethan


----------



## DanLW

A picture of my layout is attached.

http://www.realmsoftracon.com/wet/ht.bmp 


General info: 5.1 (5.2 next year) HT only room, carpeted floors, smooth paint on sheetrock ceiling. The screen if about 3' off the front wall to allow for the television. (The screen is suspended from chains and is swung up to a 3rd hook when not in use) Unfortunately, there isn't enough room to have the speakers beside the screen, so they are under the screen.


So, next year I plan to do super chunks in the 3 corners. But for now, I want to reduce the RT60 of the room as it is pretty echoey.


Now, the simple answer is to just start building 703 absorbers. But is there a more quick n dirty way that will work about as well?


I ask because in an apartment I used to live in, I lined all the walls with black sheets in an effort to darken the room. But suprisingly, those thin Wal-Mart sheets also did a good job of deadening the room.


That's what I want for now, because the echo is the most obvious problem. So, here's my main idea for a quick, dirty, and cheap way to do it.


What if I got those $20 4x8 carpets, and mounted two behind the screen, two on the back wall, and two or three along the right wall? I'm thinking of simply screwing them onto the studs.


The advantages I see using carpets is if I get the darker red stuff, it would also help darken the room a bit, and would also look nicer than 2x4 absorbers all over the place.


And if I've been reading correctly, 2x4 4" absorbers won't do much for low frequencies anyway unless they are mounted 12-16" from the wall.


So, would this work well, or am I an idiot who would be better served with $180 worth of 703 or mineral wool?


And one other question on super chunks. The standard way is 703 stacked floor to ceiling. Has anybody tried stacking bags of fiber fill insulation floor to ceiling? It's basically pulverized newspaper squeezed into 25lb bags with dimensions of approx. 2'x1.5'x1'. And it's about $10/bag. Would that possibly work?


Thanks!


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/12133287
> 
> 
> That is what the test data shows. What difference has it made in the sound?



Unknown. I haven't moved my equipment into the room yet. It will be a few weeks before all of that goes in. So I won't have a before and after impression of the space.


----------



## agbrander

Thanks Ethan - but my question is whether it is worth the effort to *fill* the corners with Roxul, requiring 24 sheets and 72 cuts, or whether having 4" roxul in the corner with an air gap behind it (8 sheets, 8 angle cuts), would be sufficient for my needs... I certainly don't think the bass traps are a silly tweak, just don't know whether I would be able to tell the difference in the sound between one approach and the other.


Particularly interested in your opinion, since it was your FAQ i got the air gap bass trap design from








. Thank you SO much for putting that together, it was very informative


Alex









> Quote:
> Originally Posted by *Ethan Winer* /forum/post/12133778
> 
> 
> Yes, it's worth it! I have two state of the art systems in my house, and both systems added together cost _way_ less than many audiophiles drop on their turntable alone. What makes my system state of the art is extensive room treatment. Well, that and professional quality loudspeakers.
> 
> 
> Bass traps and other acoustic treatment are not a silly audiophile tweak that can be appreciated only with $40k apiece loudspeakers.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan


----------



## yngdiego




> Quote:
> Originally Posted by *agbrander* /forum/post/12134296
> 
> 
> ...but my question is whether it is worth the effort to *fill* the corners with Roxul, requiring 24 sheets and 72 cuts, or whether having 4" roxul in the corner with an air gap behind it (8 sheets, 8 angle cuts), would be sufficient for my needs...
> 
> Alex



If you get an electric turkey carving knife from walmart for $15, it makes cutting OC703 like slicing butter. I don't know how easy to cut the Roxul is though. It's really no effort, clean, and VERY quick. I was surprised how fast it went. I cut 96 'super chunks' in pretty short order.


----------



## Ethan Winer

Alex,



> Quote:
> Originally Posted by *agbrander* /forum/post/12134296
> 
> 
> my question is whether it is worth the effort to *fill* the corners with Roxul, requiring 24 sheets and 72 cuts, or whether having 4" roxul in the corner with an air gap behind it (8 sheets, 8 angle cuts), would be sufficient for my needs.



Filling the corner is better, but not proportionately. So if the total cost of material is the limiting factor, you'll do better to spread the material around into other corners. But if "best" is the priority, and you don't mind three times more fiberglass and labor to get (approx) 25 percent better, then filling is great.


--Ethan


----------



## Landho

We're not at the liberty to consume the corners in the rear of our our room with angled bass traps... there will be 14" fiberglass columns with speakers on or in them (this will be a 9.1 setup)... Fortunately, we are at the liberty to consume the wall and behind the corners do to the coincidental "room in room" we're working with... I was wondering if this concept, the one on the right in the image, would be considered an acceptible solution for the rear corner bass traps... there will be an Earthquake SuperNova 15" in the front of the room, not sure how we will phase it but the mfg recommends pointing it at an angle towards the centeral listening point... the room dimensions are 22' long and 18' wide, w/ 8' ceilings and it will be a mostly sealed room, thick carpeted floors, sheetrock &/or fabric walls.


We also have the freedom to create recessed, fabric covered cavities in the wall almost whereever is necessary... but we're focusing only on the reflection point and the corners.


Also, R19 doesn't have to be used there, that was just entered to convey the concept and because we have lots of it...


----------



## dunragit

I am about to build a 2x6 floor over a concrete garage floor and I was wondering if I should fill the spaces between the floor joists with insulation? Will this improve my acoustics?


----------



## yngdiego

I'm working on building out my cozy 10x12x8 HT. The 50" plasma TV will be placed in front of a window, with the center speaker directly under it. I want to get some heavy velvet blackout curtains for the window. I have a whole stack of OC703 I'm using for treatments around the room. The window is about 24" off the floor.


So my question is, should I order short curtains and cover the wall directly under the window with OC703, or order curtains that go to the floor and forget about the OC703? I'm thinking the OC703 would be the better acoustical solution. But I think the curtains going to the floor would look better.


Since the area in question is only 24" high and about 40" wide, does it really make much of a difference?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Landho* /forum/post/12156860
> 
> 
> ...
> 
> We also have the freedom to create recessed, fabric covered cavities in the wall almost whereever is necessary... but we're focusing only on the reflection point and the corners.
> 
> 
> Also, R19 doesn't have to be used there, that was just entered to convey the concept and because we have lots of it...



Using a denser fiberglass such as 703, this may work. How much depth do you have for cavities? Does this depth exist behind all 4 walls?


Regards,

Terry


----------



## Landho




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/12159464
> 
> 
> How much depth do you have for cavities? Does this depth exist behind all 4 walls?



Behind the rear wall of the room there is about 4 feet if we needed it, the front of the room will have a false wall made of fabric and there will be about 2' up there.


thanks!


----------



## agbrander

Thanks Ethan, that's exactly the info I was looking for. Given that I am only going to be living here another 9 months, I will live with the air gap, and then fill when I build a permanent HT next time.




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/12142567
> 
> 
> Alex,
> 
> 
> 
> 
> Filling the corner is better, but not proportionately. So if the total cost of material is the limiting factor, you'll do better to spread the material around into other corners. But if "best" is the priority, and you don't mind three times more fiberglass and labor to get (approx) 25 percent better, then filling is great.
> 
> 
> --Ethan


----------



## DanLW

My post here was a serious one...


----------



## Ethan Winer

Sorry Dan, I guess everyone thought someone else would help you.











> Quote:
> Originally Posted by *DanLW* /forum/post/12133793
> 
> 
> Now, the simple answer is to just start building 703 absorbers. But is there a more quick n dirty way that will work about as well?



Moving blankets?


The problem with thin treatments is they affect only the highest frequencies, and proper treatments absorbs over as wide a range as possible.



> Quote:
> suprisingly, those thin Wal-Mart sheets also did a good job of deadening the room.



Maybe not as good as it might seem at first blush. Again, thin materials help a little, but they're not a good solution if you're at all serious about sound quality.



> Quote:
> What if I got those $20 4x8 carpets



Same problem.



> Quote:
> And if I've been reading correctly, 2x4 4" absorbers won't do much for low frequencies anyway unless they are mounted 12-16" from the wall.



Not so, assuming you mean rigid fiberglass. Further, if you put them across corners they'll do an even better job at bass frequencies.



> Quote:
> Has anybody tried stacking bags of fiber fill insulation floor to ceiling?



Sure, and I mention using bagged insulation in my Acoustics FAQ , which will be a useful read for you generally.


--Ethan


----------



## DanLW

Wow, a reply from the great one himself! (And that's meant in all sincerity)


Okay, so as I feared, while something as simple as sheets or carpet does help a little (and noticeably), it won't help near as well as even just 2" rigid fiberglass treatments. So I guess the sheet lined room was just a small taste of the improvement I can obtain from going "all the way".


I did read your FAQ several days ago, and it had lots of excellent info. I didn't remember reading about the bagged insulation...


[ checks]


I tried searching for bag, bags, bagged, and insulation and can't seem to find anything about bagged insulation. After a bit of searching, all I could find is a post on another forum where somebody said he asked you about the cellulose bag design, and you said it should work decently.

http://www.audiocircle.com/circles/i...?topic=44090.0 


I even tried registering at the musicplayer forums and searching, without much luck. (stupid 6 month search window).


So, whereas for stacking bagged insulation I'd probably end up spending $40-$50 per corner trap, whereas if I used 12 sheets of rigid fiberglass, I'd end up spending roughly twice as much. So, I guess my question is, do rigid fiberglass super chunks perform much better than cellulose super chunks, or is the advantage of fiberglass mainly the fact that it fits into the corner better and can be made to look nicer?


I think I may go ahead and do the carpet thing and add 4" absorbers down the road. While they won't do much for all but the higher frequencies (above 5KHz? 10?), they'll at least darken the room a bit. And they'd look much nicer than hanging the sheets like I did last time!


Thanks!


----------



## nathan_h

"Another great and inexpensive way to make a bass trap - if you have a lot of room - is to place bales of rolled up fluffy fiberglass in the room corners. These bales are not expensive, and they can be stacked to fill very large spaces. Better still, they are commonly available and you don't even have to unpack them! Just leave the bales rolled up in their original plastic wrappers, and stuff them in and near the room corners wherever they'll fit. Stack them all the way up to the ceiling for the most absorption." from http://www.ethanwiner.com/acoustics.html


----------



## Ethan Winer

Thanks Nathan, that's exactly the part of my FAQ I was referring to.


----------



## DanLW

The thing is, the cellulose fiber is a little more compact, but still quite dense, at 25lb/bag. Definitely denser than fiberglass rolls.


I guess the only way to find out for sure is to get both and run LF sweeps with rolls, and again with bags.


One quick question. Which db meter is preferrable - the Radio Shack analog or digital meter? I thought I read somewhere that the analog meter was preferrable.


----------



## Ethan Winer




> Quote:
> Originally Posted by *DanLW* /forum/post/12172651
> 
> 
> Which db meter is preferrable - the Radio Shack analog or digital meter?



I prefer the digital, but either is fine.


--Ethan


----------



## yngdiego




> Quote:
> Originally Posted by *yngdiego* /forum/post/12157895
> 
> 
> I'm working on building out my cozy 10x12x8 HT. The 50" plasma TV will be placed in front of a window, with the center speaker directly under it. I want to get some heavy velvet blackout curtains for the window. I have a whole stack of OC703 I'm using for treatments around the room. The window is about 24" off the floor.
> 
> 
> So my question is, should I order short curtains and cover the wall directly under the window with OC703, or order curtains that go to the floor and forget about the OC703? I'm thinking the OC703 would be the better acoustical solution. But I think the curtains going to the floor would look better.
> 
> 
> Since the area in question is only 24" high and about 40" wide, does it really make much of a difference?




Haven't seen any replies to my question. Thoughts?


----------



## bpape

Why don't you do both if they're in a place and of a size that you need that much surface area? You can easily do 703 behind the curtains.


Bryan


----------



## Sax

What are you using to cover 48x24x2 703, and are you putting it in a frame or just covering it with some kind of speaker cloth. And what are you using to hang it on the wall.


----------



## pepar




> Quote:
> Originally Posted by *Sax* /forum/post/12185179
> 
> 
> What are you using to cover 48x24x2 703, and are you putting it in a frame or just covering it with some kind of speaker cloth. And what are you using to hang it on the wall.


 Start researching here . It's OC SelectSound Black, but it could have just as easily been OC 703.


----------



## eugenep01

Can I use some other/cheaper material to cover panel frames? I went to

fabric store and saw some good cotton material and was thinking if I could wrap my panels with that $8/yard material?

I read through forums and couldn't find a reason for using GOM - which is

polyester and it is see thru material versus higher thread cotton or something

else. Please suggest.


----------



## pepar




> Quote:
> Originally Posted by *eugenep01* /forum/post/12195611
> 
> 
> Can I use some other/cheaper material to cover panel frames? I went to
> 
> fabric store and saw some good cotton material and was thinking if I could wrap my panels with that $8/yard material?
> 
> I read through forums and couldn't find a reason for using GOM - which is
> 
> polyester and it is see thru material versus higher thread cotton or something
> 
> else. Please suggest.



No experimentation is needed, it works. First time and every time. No posting on AVS to find out is anyone else has successfully used . No spending my valuable time trying to "save a buck."


----------



## jon8christine




> Quote:
> Originally Posted by *eugenep01* /forum/post/12195611
> 
> 
> Can I use some other/cheaper material to cover panel frames? I went to
> 
> fabric store and saw some good cotton material and was thinking if I could wrap my panels with that $8/yard material?
> 
> I read through forums and couldn't find a reason for using GOM - which is
> 
> polyester and it is see thru material versus higher thread cotton or something
> 
> else. Please suggest.



I just purchased the burlap they sell at atsacoustics.com for $7 a yard. Don't know, but I'm sure it works.


----------



## yngdiego




> Quote:
> Originally Posted by *Sax* /forum/post/12185179
> 
> 
> What are you using to cover 48x24x2 703, and are you putting it in a frame or just covering it with some kind of speaker cloth. And what are you using to hang it on the wall.



I'm using a different and cheaper method. I went to my local Home Depot and got some fiberglass resin. I brushed some on all the edges, and it produces a nice firm edge.


Then I use some 3M spray adhesive to attach my GOM 701 black material. Finally, I'm using the rotofast hangers for wall mount.


Now I'm just part way through my project and at the resin stage. But later today I'll be gluing the fabric on two panels. I think they will look just fine, and I didn't need to take the time to build a wood frame.


----------



## bpape

People use GOM for the following reasons:


- It's fire rated.

- It comes in 48 colors

- It matches their false walls with speakers behind them where you NEED the acoustical transparency of the FR701-2100 GOM


Bryan


----------



## Duaned

I wonder, does the glue keep any of the sound from being absorbed?




> Quote:
> Originally Posted by *yngdiego* /forum/post/12197094
> 
> 
> I'm using a different and cheaper method. I went to my local Home Depot and got some fiberglass resin. I brushed some on all the edges, and it produces a nice firm edge.
> 
> 
> Then I use some 3M spray adhesive to attach my GOM 701 black material. Finally, I'm using the rotofast hangers for wall mount.
> 
> 
> Now I'm just part way through my project and at the resin stage. But later today I'll be gluing the fabric on two panels. I think they will look just fine, and I didn't need to take the time to build a wood frame.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Duaned* /forum/post/12214556
> 
> 
> I wonder, does the glue keep any of the sound from being absorbed?



If used too much, yes. This can take the "porous" out of "porous absorber."







It is best to confine spray adhesive to the back edges and corners of panels. Use the lightest amount to get the job done.


Regards,

Terry


----------



## yngdiego




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/12214796
> 
> 
> If used too much, yes. This can take the "porous" out of "porous absorber."
> 
> 
> 
> 
> 
> 
> 
> It is best to confine spray adhesive to the back edges and corners of panels. Use the lightest amount to get the job done.
> 
> 
> Regards,
> 
> Terry



Oh that's good to know. I'm ready to cover a few 2x4 sheets with GOM today, and was planning on spraying the front and sides with the spray adhesive. I'll be sure to go extra light....very good input!


I did try and go very light on the sides with resin, so that much did cross my mind.


----------



## nathan_h

Anybody using these? They look very promising.

http://www.waveguideacousticsolutions.com/index.html 


I've been talking with the proprietor, and will hopefully see some measurement data related to them.


----------



## yngdiego




> Quote:
> Originally Posted by *nathan_h* /forum/post/12224238
> 
> 
> Anybody using these? They look very promising.
> 
> http://www.waveguideacousticsolutions.com/index.html
> 
> 
> I've been talking with the proprietor, and will hopefully see some measurement data related to them.



Would this be a product to use on the back wall behind the listening position?


----------



## eugovector




> Quote:
> Originally Posted by *nathan_h* /forum/post/12224238
> 
> 
> Anybody using these? They look very promising.
> 
> http://www.waveguideacousticsolutions.com/index.html
> 
> 
> I've been talking with the proprietor, and will hopefully see some measurement data related to them.



Great price if they work. Not factoring in time, There has to be, what, about $20 in Material cost to DIY one of these?


----------



## eugovector




> Quote:
> Originally Posted by *yngdiego* /forum/post/12224385
> 
> 
> Would this be a product to use on the back wall behind the listening position?



That would be the most common position, but it all depends on the size, shape, and setup of your room.


----------



## yngdiego

I'm in the final stages of getting my small HT set up. The room has 8' ceilings, and is located on the second story. Walls are typical modern home construction dry-wall. The closet doors have been completely removed. Attached is to-scale drawing of the room and equipment.


Installed treatments are:


1) OC703 super chunk bass traps in all four corners, floor to ceiling.

2) 12" x 2" x 8' OC703 mounted on both sides of the window behind the main speakers.

3) Pending: Thick velvet blackout curtains in front of the window, behind the plasma.


Pending placement: Six 2'x4'x2" OC703 panels.


Now my questions are:


1) I plan on putting two panels at the FRPs on the left and right for the main speakers. The mains are floor standing Veritas v2.4 models. Should orient the OC703 panes in the vertical position or horizontal? The free FRP software I used showed a 4' long horizontal area on the side walls as the FRP, and one company that does freebie recommends for treatments also recommended horizontal. But given the speakers are tall floor standing models, I would think a vertical orientation would be better?


2) The same company that recommended the horizontal side panels, also recommended one panel _directly_ above each main speaker, butted up against the corner bass traps. These aren't FRPs, so do I really need to treat directly above the speaker?


3) For the ceiling FRP, the freebie software shows a 2' deep (top to bottom of the picture) by 6' wide (left to right). Could I do two 2'x4' panes pointing top to bottom in the picture, spaced apart say six inches? Or should I put them end-to-end left-to-right to form a 2' x 8' panel? I'm thinking the first option is preferable.


4) Along the back closet wall, should I have a diffusion panel inbetween the two bass traps?


5) Should I place an additional two panels along the side walls more towards the loveseat?



Thanks!


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12234228
> 
> 
> I'm in the final stages of getting my small HT set up. The room has 8' ceilings, and is located on the second story. Walls are typical modern home construction dry-wall. The closet doors have been completely removed. Attached is to-scale drawing of the room and equipment.
> 
> 
> Installed treatments are:
> 
> 
> 1) OC703 super chunk bass traps in all four corners, floor to ceiling.
> 
> 2) 12" x 2" x 8' OC703 mounted on both sides of the window behind the main speakers.
> 
> 3) Pending: Thick velvet blackout curtains in front of the window, behind the plasma.
> 
> 
> Pending placement: Six 2'x4'x2" OC703 panels.



It's very easy to over-deaden a small room. I'd do the bass traps, the walls behind the front speakers AND the FRP on the REAR wall. And then I would listen and take measurements before adding any more treatments. I might also do the ceiling before the "listen and measure" step.


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/12234356
> 
> 
> It's very easy to over-deaden a small room. I'd do the bass traps, the walls behind the front speakers AND the FRP on the REAR wall. And then I would listen and take measurements before adding any more treatments. I might also do the ceiling before the "listen and measure" step.



I was considering a 30"x30" diffusion panel on the rear wall...but haven't bought it yet. Is diffusion needed in this small of a space? Or like you said, should the rear wall get an OC703 panel at the FRP?


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12235100
> 
> 
> I was considering a 30"x30" diffusion panel on the rear wall...but haven't bought it yet. Is diffusion needed in this small of a space? Or like you said, should the rear wall get an OC703 panel at the FRP?



Diffusion could work, and maybe even be better than absorption. I think it depends on the distance between the wall and your seats. In looking at your drawing, I see a closet and a door behind your listening position. Where would you place treatment back there?


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12235100
> 
> 
> I was considering a 30"x30" diffusion panel on the rear wall...but haven't bought it yet. Is diffusion needed in this small of a space? Or like you said, should the rear wall get an OC703 panel at the FRP?



FWIW, I am considering placing diffusors over some of my wall carpeting to breathe some "air" back into my room. If you want to see what I'm talking about, visit my site linked in my sig.


My room is 13' x 21' x 8'.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12234228
> 
> 
> I'm in the final stages of getting my small HT set up. The room has 8' ceilings, and is located on the second story. Walls are typical modern home construction dry-wall. The closet doors have been completely removed. Attached is to-scale drawing of the room and equipment.



I'd move the side surrounds forward to just inches behind the ears of your audience.


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/12236425
> 
> 
> Diffusion could work, and maybe even be better than absorption. I think it depends on the distance between the wall and your seats. In looking at your drawing, I see a closet and a door behind your listening position. Where would you place treatment back there?
> 
> ...
> 
> I'd move the side surrounds forward to just inches behind the ears of your audience.



I would place the diffuser on the rear closet wall between the two super chunk bass traps. A 30"x30" would fit nicely in the space. The distance from the rear wall to listening position is 5 feet.


The rear surrounds are located very close to the Dolby recommended 110 degrees. How would moving them closer to the listener be beneficial?


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12236798
> 
> 
> I would place the diffuser on the rear closet wall between the two super chunk bass traps. A 30"x30" would fit nicely in the space. The distance from the rear wall to listening position is 5 feet.
> 
> 
> The rear surrounds are located very close to the Dolby recommended 110 degrees. How would moving them closer to the listener be beneficial?



They are tight against the rear wall. Right now the rear lobes are crashing into the corners. I'll bet that they perform more like monopole than dipole mounted like this. And I subscribe to the THX recommendation that they by even with, or _slightly_ behind listeners.


Just my $.02.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12236798
> 
> 
> I would place the diffuser on the rear closet wall between the two super chunk bass traps. A 30"x30" would fit nicely in the space. The distance from the rear wall to listening position is 5 feet.



That would work fine, I imagine, if he left the closet doors open and had nothing hanging in the closet.


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/12237029
> 
> 
> That would work fine, I imagine, if he left the closet doors open and had nothing hanging in the closet.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ...
> 
> They are tight against the rear wall. Right now the rear lobes are crashing into the corners. I'll bet that they perform more like monopole than dipole mounted like this. And I subscribe to the THX recommendation that they by even with, or slightly behind listeners.



Closet doors have been removed, and nothing is in the closet except the bass traps.










How high does THX recommend the rear surrounds be placed? I've always heard at ear level when stand up, which puts them a couple of feet higher than the listening position.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12237065
> 
> 
> Closet doors have been removed, and nothing is in the closet except the bass traps.



DOH! Well, if he's not going to use the closet as a closet, I'd consider removing it (or at least the small stub on the left rear). But whether he removes it or not, I'm not sure how much the trap in the door-side of the closet would do. If he hangs anything there, any mid- to upper-frequency treatments will not be effective.



> Quote:
> How high does THX recommend the rear surrounds be placed? I've always heard at ear level when stand up, which puts them a couple of feet higher than the listening position.



Yep, height-wise a couple of feet above the ears.


----------



## eugenep01

I am building stage for my home theater, and was wandering if sand filled stage a must. What else can be used. I am new to theater building and

looking for suggestions.

I have been reading a lot during my theater construction phase and getting

all sorts of useful info from this forum.

What I have done is put carpet pad underneath theater stage to separate it

from floor, and have about 1/2" space to the walls.

I would appreciate your suggestions/advise.


Eugene.


----------



## pepar




> Quote:
> Originally Posted by *eugenep01* /forum/post/12255100
> 
> 
> I am building stage for my home theater, and was wandering if sand filled stage a must. What else can be used. I am new to theater building and
> 
> looking for suggestions.
> 
> I have been reading a lot during my theater construction phase and getting
> 
> all sorts of useful info from this forum.
> 
> What I have done is put carpet pad underneath theater stage to separate it
> 
> from floor, and have about 1/2" space to the walls.
> 
> I would appreciate your suggestions/advise.
> 
> 
> Eugene.



FWIW, I wanted mine coupled to the floor and built the riser so that I could (some time in the future) add bass transducers. You can see my construction and comments here .


----------



## eugenep01

I am talking about stage in front, where front speakers and sub will be placed.

It seems like most of people fill it with sand, and try to decople from walls, not sure about floor though. By the way I have been to your page a few times, getting ideas, thank you. One thing I noticed you have hardwood on the floor, you don't have problems with that?


----------



## pepar




> Quote:
> Originally Posted by *eugenep01* /forum/post/12259006
> 
> 
> I am talking about stage in front, where front speakers and sub will be placed.
> 
> It seems like most of people fill it with sand, and try to decople from walls, not sure about floor though. By the way I have been to your page a few times, getting ideas, thank you. One thing I noticed you have hardwood on the floor, you don't have problems with that?



DOH! I'm sorry. Yes most are filling front stages with sand. I would, too, if I had one.


In the area between the first row and the screen, there is a throw rug with the heaviest, springiest rubber pad I could find. In other areas, the amount of *hard*wood exposed is dwarfed by the LaZBoys, the 2" fiberglass covering the cavity behind my false wall and first reflection points, as well as the wall carpet. IN fact, I am planning on lowering the LCR speakers allowing a reduction in the size of the front side absorbers and installing some diffusors to recover some "air" in the room.


----------



## zmisst




> Quote:
> Originally Posted by *yngdiego* /forum/post/12137221
> 
> 
> If you get an electric turkey carving knife from walmart for $15, it makes cutting OC703 like slicing butter. I don't know how easy to cut the Roxul is though. It's really no effort, clean, and VERY quick. I was surprised how fast it went. I cut 96 'super chunks' in pretty short order.



Stanley Sharptooth Saw (can get on amazon) cuts Roxul (and thermal fiber brand rock wool) and rigid foam board like butter. It seems that it would cut OC703 well also.


----------



## Bluewaterboy

Well, I have been following this and other threads for a long time and have been reluctant to take the plunge because it seemed complicated to get it right and the cost was too much especially looking at off the shelf products. I liked the look of the studio foams like Sonex and Aurelex but the cost to treat my room was approximately $800. I saw several comments on here that the cheap foam does not work, B.S. I bought foam from the foam factory on e-bay and installed 8 bass traps in (2) 8 ft columns in the front of the theater and 54 1 foot sq. 3" wedges at all of the FRP's and the results were dramatic. The sound improved so much that my 7 year old and my wife both described the sound improvement much the way I heard it. I am extremely happy and all for $140 delivered to my door. Thanks for all of the info I guess all I am trying to say is it is not as complicated as it may seem.


Rich


----------



## GsHTPC

Hey guys,

I have a couple of questions regarding DIY Acoustic Panels. I'm trying to do this the economical way DIY BABY! The retail products are just too expensive and from what I've seen the DIY stuff is just as effective but at a fraction of the cost. Here are my questions.


1) Is there a good substitue to OC703. Can I just use any old fiberglass insulation of R13 rating? Or does it have to be OC703? Cant find this in any local hardware store :-(


2) My plan was to build a tiered type of panel. Build a rectangular wooden frame stuff it with fiberglass insullation, peg board on one side wrap it in poly matting then cover it with speaker covering. Second would be to build a smaller panel same way and just change the color to mix up the contrast for astethic reasons to match the decor of the room. The question is if I tier the acoustic panels two levels will this affect the reflective properties and efecttiveness of the panel?


3) can people post some pics of thier panels. I'm looking for some ideas and I've already seen a couple of really good ones.


I have an 18x20x8 foot room with 2 15" 1000w subs sealed enclosure and 7.1 surround 650w reciever. PSB Silver's all around.


----------



## BasementBob

GsHTPC:


You can use anything with similar absorption coefficients, and get similar results.

This page lists a few alternatives
http://www.bobgolds.com/AbsorptionCoefficients.htm 


Your local hardware store won't sell rigid insulation. But you can get them from many insulation distributors in your area. Check your yellow pages.
http://www.bobgolds.com/InsulationContractors.htm 



> Quote:
> can people post some pics of thier panels. I'm looking for some ideas and I've already seen a couple of really good ones.



There's lots of them around. Once upon a time I collected a few links and put them at
http://www.bobgolds.com/AbsorptionCoefficients.htm 

starting about 80% of the way down look for "Jon Risch's Absorbers" through "Vshine's Wall Absorbers"


----------



## bpape




> Quote:
> Originally Posted by *Bluewaterboy* /forum/post/12319447
> 
> 
> Well, I have been following this and other threads for a long time and have been reluctant to take the plunge because it seemed complicated to get it right and the cost was too much especially looking at off the shelf products. I liked the look of the studio foams like Sonex and Aurelex but the cost to treat my room was approximately $800. I saw several comments on here that the cheap foam does not work, B.S. I bought foam from the foam factory on e-bay and installed 8 bass traps in (2) 8 ft columns in the front of the theater and 54 1 foot sq. 3" wedges at all of the FRP's and the results were dramatic. The sound improved so much that my 7 year old and my wife both described the sound improvement much the way I heard it. I am extremely happy and all for $140 delivered to my door. Thanks for all of the info I guess all I am trying to say is it is not as complicated as it may seem.
> 
> 
> Rich



Imagine the improvement if you'd used something that was actually effective below 100Hz or so. Yes - it will help some - but nothing like thicker mineral wool, 703, etc. down in the deep bass.


In any case, you've at least addressed part of the room acoustics which is more than many people do.


Bryan


----------



## nathan_h




> Quote:
> Originally Posted by *bpape* /forum/post/12327699
> 
> 
> Imagine the improvement if you'd used something that was actually effective below 100Hz or so. Yes - it will help some - but nothing like thicker mineral wool, 703, etc. down in the deep bass.
> 
> 
> In any case, you've at least addressed part of the room acoustics which is more than many people do.
> 
> 
> Bryan



Their corner traps look pretty good down to 125hz (which is the lowest they publish data for). Doesn't look as effective as treatments made of fiberglass but I'm guessing it sounds about as good as auralex foam products. The thing that would worry me is their "life expectancy" of 5-10 years. I've had some auralex panels for more than 5 years, and they are about the same as the day I bought them. And I'm guessing my real traps panels will still be solid, even after I have departed from this life!


But for someone not DIY inclined, on a tight budget, this cheapo foam (which is fire-rated, according to the web site) could be a way to save a few bucks and "get religion" with regard to acoustic treatments. Is it the best solution? Heck no. Would it be worth paying a bit more and getting a fiberglass-based solution? I think so. But I'd guess in almost any room, it would make a positive difference compared to a "no-treatments" option.


----------



## luckybeanbean

Dear all, I am going to construct a home theatre within a month. I just found out that the only thing I can get in my area is 1" 705 FRK. If I am planning to make a 2" one, do I need to peel off the paper facing before combining them? Thanks


----------



## pepar




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/12333647
> 
> 
> Dear all, I am going to construct a home theatre within a month. I just found out that the only thing I can get in my area is 1" 705 FRK. If I am planning to make a 2" one, do I need to peel off the paper facing before combining them? Thanks



Peel? I didn't know it was peel-able.


Where are you located?


----------



## luckybeanbean




> Quote:
> Originally Posted by *pepar* /forum/post/12335445
> 
> 
> Peel? I didn't know it was peel-able.
> 
> 
> Where are you located?



I am located in Hong Kong. So, in that case, I am stuck with 1". If I leave the facing on, and when I stack it, the air can't go through, so 1" +1" FRK can't = 2" FRK, right?


----------



## pepar




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/12335945
> 
> 
> I am located in Hong Kong. So, in that case, I am stuck with 1". If I leave the facing on, and when I stack it, the air can't go through, so 1" +1" FRK can't = 2" FRK, right?



That would be my guess, but hopefully Bob, Bryan or someone will chime in.


----------



## bpape

For places you need only 1", just turn it around. If you need 2", peel off the FRK from one of the pieces, put the foil toward the wall from the other piece and use a bit of spray adhesive to bond them together.


If you want the FSK exposed in some places, you still should peel off one of the pieces and bond together. The other issue with the FSK with the foil out is that it is visible for light reflection through porous cloth. If you can get just the FSK separately, you should attach it with the paper side out so you minimize light reflection issues.


Bryan


----------



## aham23

ducts. how can i treat the existing duct work to reduce sound escaping to other rooms and reduce vibrations and sound when the HVAC is running.


it is not an option to replace the runs in the HT with flex duct. is their anything simple that you all can recommend? what should i wrap the duct work with?


i did a quick search, but came up with zero.


much thanks. later.


----------



## Blackcat2950

Quick question for you guys - haven't seen it addressed yet in this thread:


I have a 15 cu. ft. vented, A/V equipment cabinet that, due to house layout limitations, must be exhausted into the listening room. I'm using quiet DC fans from Active Thermal Mgmt, but still want to acoustically insulate the inside of the exhaust duct (reduce fan & air speed noise). I'm concerned about using any fiberglass-based product since the deadening material will be in the air stream of the living environment.


Is there any commonly agreed-to, best approach/material for this purpose? I know there are many "duct liners" on the market, but it seems you guys are using them for other purposes (walls, external to pipes/ducts, etc.). I need something that will deaden fan whine and air noise, be easily installed a duct, and yet be 100% safe to run within an air steam internal to the home (no fiberglass, no toxic/obnoxious odors) . Any ideas?


----------



## nathan_h




> Quote:
> Originally Posted by *aham23* /forum/post/12372532
> 
> 
> ducts. how can i treat the existing duct work to reduce sound escaping to other rooms and reduce vibrations and sound when the HVAC is running.
> 
> 
> it is not an option to replace the runs in the HT with flex duct. is their anything simple that you all can recommend? what should i wrap the duct work with?
> 
> 
> i did a quick search, but came up with zero.
> 
> 
> much thanks. later.



I think most solutions require replacing a section of the existing duct with something better: a baffle, flexible ducting, etc.


----------



## nathan_h




> Quote:
> Originally Posted by *Blackcat2950* /forum/post/12378135
> 
> 
> Quick question for you guys - haven't seen it addressed yet in this thread:
> 
> 
> I have a 15 cu. ft. vented, A/V equipment cabinet that, due to house layout limitations, must be exhausted into the listening room. I'm using quiet DC fans from Active Thermal Mgmt, but still want to acoustically insulate the inside of the exhaust duct (reduce fan & air speed noise). I'm concerned about using any fiberglass-based product since the deadening material will be in the air stream of the living environment.
> 
> 
> Is there any commonly agreed-to, best approach/material for this purpose? I know there are many "duct liners" on the market, but it seems you guys are using them for other purposes (walls, external to pipes/ducts, etc.). I need something that will deaden fan whine and air noise, be easily installed a duct, and yet be 100% safe to run within an air steam internal to the home (no fiberglass, no toxic/obnoxious odors) . Any ideas?



If possible, add in lots of twists and turns in the ductwork.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/12385861
> 
> 
> If possible, add in lots of twists and turns in the ductwork.



Don't turns produce their own airflow noise?


----------



## GsHTPC

I'm in the process of building accoustic panels, with 1x4 the panels are 4x2. I'm using OC703 2" My question is this. Should I double stack the OC703 so it's 4" thick? Is there any benefit? Should I or is there value to adding some poly batting on the front and backside of the OC703? I want to keep the fiberglass as isolated as possible.


----------



## Terry Montlick




> Quote:
> Originally Posted by *GsHTPC* /forum/post/12393048
> 
> 
> I'm in the process of building accoustic panels, with 1x4 the panels are 4x2. I'm using OC703 2" My question is this. Should I double stack the OC703 so it's 4" thick? Is there any benefit? Should I or is there value to adding some poly batting on the front and backside of the OC703? I want to keep the fiberglass as isolated as possible.



Yes, there is an advantage to a 4" thickness. It will reach about 1 octave lower in bass, all other things being equal (which of course they never are!







). To save money, you can use polyester batting on the *backside* of the panels. This should give comparable low frequency performance, though maybe not as smooth at higher frequencies. 703 fibers are pretty well bound, and I wouldn't worry about them penetrating the fabric faces of the panels.


Regards,

Terry


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/12386495
> 
> 
> Don't turns produce their own airflow noise?



I'm not an expert, but not that I'm aware of unless:


1. There is a very high velocity of air, or

2. There are lots of parallel surfaces


I think twists and turns can help, but guess the ultimate solution might be a dedicated isolation baffle:

http://paulmadison.com/baffle.html


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/12396063
> 
> 
> I'm not an expert, but not that I'm aware of unless:
> 
> 
> 1. There is a very high velocity of air, or
> 
> 2. There are lots of parallel surfaces
> 
> 
> I think twists and turns can help, but guess the ultimate solution might be a dedicated isolation baffle:
> 
> http://paulmadison.com/baffle.html



Cool! Which end gets the cheese?


----------



## Southey

Hey Folks,


Sorry if you have already covered this tons, but I just don't have the time to read through 93 pages of posts. I am having my home theatre set up next Wednesday. I didn't do any soundproofing as far as insulating the walls or ceilings in my basement dedicated room. When I was visiting with my home theatre guy yesterday he showed me these new panels that go on your walls. they are about 2' x 4' and about 3" or 4" thick. My room is about 13.5' x 10'. I am just wondering how many of these you think I would need and what sort of costs I should be paying if I was to buy them or have him install them for me. I would like to buy them myself somewhere and install them, I am just unsure about strategies which is why I hired someone to begin with. Can you guys please offer any advice and maybe mention some brands I could look at. I am just outside of Calgary, Alberta, Canada. Thanks everybody and I love this forum.


----------



## bpape

You'll find pricing all over the place. A general strategy:


Kill the front corners of the room with something relatively thick and preferably straddling the corners for bass control. The balance of the front wall should be completely covered as much as possible for a variety of reasons.


Side walls need at least a couple panels to deal with early reflections off the side wall.


Rear wall again use something thicker in the middle of the wall to help control the length related bottom end issues.


Bryan


----------



## jjackknife

BPape... the rear wall.... treating the middle is preferable to the corners? (for bass?)... just wanting confirmation. that actually would be WONDERFUL for me, since my entry door is in the back corner. *thanks* for your help.


----------



## myfipie




> Quote:
> Originally Posted by *jjackknife* /forum/post/12488411
> 
> 
> BPape... the rear wall.... treating the middle is preferable to the corners? (for bass?)... just wanting confirmation. that actually would be WONDERFUL for me, since my entry door is in the back corner. *thanks* for your help.



Actually both if you can. If a door is in the way then skip it and do the back wall and the other corner.


Glenn


----------



## Ethan Winer




> Quote:
> Originally Posted by *Southey* /forum/post/12486016
> 
> 
> I am just unsure about strategies which is why I hired someone to begin with. Can you guys please offer any advice and maybe mention some brands I could look at.



There are several vendors here that sell acoustic treatment products, we've all now replied.










Seriously, Bryan gave you the right answer, and here's my standard reply:


Room treatment is a deep subject, and a complete answer requires far more than will fit into a single reply here. So here's the short version. All rooms need:


* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further. You simply cannot have too much bass trapping. Real bass trapping, that is - thin foam and thin fiberglass don't work to a low enough frequency.


* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.


* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective. Diffusion on the rear wall behind you is also useful in larger rooms.


For the complete story see my Acoustics FAQ. 


--Ethan


----------



## nycdan




> Quote:
> Originally Posted by *nathan_h* /forum/post/12385775
> 
> 
> I think most solutions require replacing a section of the existing duct with something better: a baffle, flexible ducting, etc.



I've got 20' of straight return running along the top of one side of my soon-to-be media room. It passes through the front wall back to the mechanicals room and I'm worried about vibration when the furnace kicks on.


I was going to box it out with enough room for 3" fiberglass insulation between the duct and the sheetrock. Is this going to help significantly or should I expect to need GG and a second sheet of sheetrock. Are there any other types of baffling treatments to consider? Replacing the duct is a possibility I hadn't considered. Is that far better than the insulation or GG?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *nycdan* /forum/post/12494118
> 
> 
> I've got 20' of straight return running along the top of one side of my soon-to-be media room. It passes through the front wall back to the mechanicals room and I'm worried about vibration when the furnace kicks on.
> 
> 
> I was going to box it out with enough room for 3" fiberglass insulation between the duct and the sheetrock. Is this going to help significantly or should I expect to need GG and a second sheet of sheetrock. Are there any other types of baffling treatments to consider? Replacing the duct is a possibility I hadn't considered. Is that far better than the insulation or GG?



You could use duct liner first and, if necessary, clad the duct as well.


----------



## bpape




> Quote:
> Originally Posted by *jjackknife* /forum/post/12488411
> 
> 
> BPape... the rear wall.... treating the middle is preferable to the corners? (for bass?)... just wanting confirmation. that actually would be WONDERFUL for me, since my entry door is in the back corner. *thanks* for your help.



Treating the corners is a good overall solution. If you can't you can't. Treating the middle of the rear wall is to address a more specific issue which is the potential for nulls off the rear wall based on your seating distance - and also to add some additional general low frequency control in the length dimension opposite the screen which many times can't be treated behind effectively.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/12497545
> 
> 
> Treating the corners is a good overall solution. If you can't you can't. Treating the middle of the rear wall is to address a more specific issue which is the potential for nulls off the rear wall based on your seating distance - and also to add some additional general low frequency control in the length dimension opposite the screen which many times can't be treated behind effectively.
> 
> 
> Bryan



When I added my first reflection point absorbers, by far the biggest difference was the panel on the rear wall (5-6 feet away). The increase in clarity from the front speakers was immense. The rear wall was causing a reflection delayed by ~12ms and really messing with my brain.


----------



## traveler

When our school (private college) was redoing the music practice rooms they lined them with a material they referred to as teknam (don't know if that's the correct spelling). It's about an inch thick, rigid, and looks like it is made up of horsehair-like fibers bound together with some hard bonding agent. Are any of you familiar with the material? I have several sheets of it. Is it more for absorbing sound or diffusing it?


I have no sound treatment in my HT which is 22 ft long and 13 ft wide. The front (without the projection screen down) is all cabinetry and the speakers are inset in the front wall on the extreme right and left). Here is a picture of the front:
http://www.krauses.net/HTFrontNoScreen.JPG 


Here it is with the screen down:
http://www.krauses.net/HTRoomFront.JPG 


Finally, here is a picture of the rear of the room:
http://www.krauses.net/HTRoomRear.JPG 


As you might expect the sound from the mains and center is kinda muddy and I want to clean it up before I invest in some better main and center speakers.


Since there's not much I can do about the front behind the screen and removing the wains coat hardwood would negatively affect the WAF, I plan on running about a 3 foot wide strip of sound diffusing material (or would absorbing be better) at the top of the wains coat from front to back and covering the rear wall with diffusing material.


Your thoughts?


BTW - I have a recording engineer from the school coming over on Monday to give me his suggestions but I fear that all he knows about is deadening rather than optimizing the sound.


----------



## BasementBob

traveler:
Tectum ?

The first PDF on that page shows mounting suggestions -- namely to put it on furing strips in front of fiberglass.

The second PDF on that page shows absorption coefficients.


----------



## BasementBob

traveler:

Do you have a computer (likely, uh you're posting, but one that could be put with 20' of that HT), and a microphone/preamp with a 30' cord and mic stand(private college recording engineer), and a sound level meter (cheap)?

Do you have the DVD's: Mission To Mars, Star Wars 1 (pod race)?

Can you toe-in (turn) your left/right mains?


Some notes

- you can move the couch (modal/imaging)

- your left/right mains are against the side wall and unmoveable (3pi loading), possible PEQ

- front wall has open cupboards


How do you feel about hiring someone like UMR to come and audio calibrate what you have now?

I don't know for sure what UMR does, but it's possibly something like this: http://www.sencore.com/newsletter/No...ioCalpart2.htm


----------



## traveler

Bob,

Yup, that's the stuff. It's actually designed to eliminate sound transmission through the wall, which is not what I'm trying to do. But, will it still work for reducing audio reflection? I don't know. The mounting directions also seem to be for reduction of sound transmission. Would it really do any good to fir out the tectum with fiberglass behind it for my application?

Now, regarding your second post, Yes, I have a computer and I certainly can get a mic/preamp and mic stand (the Media Resource Center reports to me







) and I have a sound level meter. Yes I have Star Wars 1. No, I can't turn the speakers at all. However, once I get the room cleaned-up accoustically I plan on replacing the Left, Right, and center speakers and the L&R will be freestanding towers.


I wouldn't have a problem with hiring UMR to calibrate the room depending what the cost would be. (I work for a school, remember? That means that I get paid peanuts







) Perhaps I'll give them a call next week and find out what they would charge.


I just saw what they charge and the travel costs alone would be prohibitive. Perhaps there's someone in St. Louis that can do this.


----------



## traveler

Bob,

Looking at your notes. Yes, the couch can move but it can't leave the room (the room was actually enclosed with the couch in it and afterwards we learned that it won't fit out the door (Doh!) The front wall does not have open cupboards (unless I removed the doors, but why would I want to do that?)


----------



## jjackknife




> Quote:
> Originally Posted by *pepar* /forum/post/12498838
> 
> 
> ... by far the biggest difference was the panel on the rear wall (5-6 feet away). The increase in clarity from the front speakers was immense...



Wow... that was educational & enlightening. i was going to completely blow off the back wall, thought it was the _least_ important! thanks to both of you, pepar & bpape. I may need to look into a professional calibration before i frustrate myself!


----------



## pepar




> Quote:
> Originally Posted by *jjackknife* /forum/post/12502111
> 
> 
> Wow... that was educational & enlightening. i was going to completely blow off the back wall, thought it was the _least_ important! thanks to both of you, pepar & bpape. I may need to look into a professional calibration before i frustrate myself!



A pro would definitely be able to analyze and treat any acoustical problems. You'll spend more money than DIY, but it would "git 'er done" quickly without reading a lot of forum threads.


----------



## umr




> Quote:
> Originally Posted by *traveler* /forum/post/12501846
> 
> 
> ...
> 
> I just saw what they charge and the travel costs alone would be prohibitive. Perhaps there's someone in St. Louis that can do this.



Bob,


If that is a problem forget the search. You are very unlikely to find anyone for that price that will do a credible job. My pricing for audio is exceptionally low compared to the rest of the market.


----------



## traveler

umr,

I just sent you a PM.


----------



## BasementBob

Pepar:



> Quote:
> A pro would definitely be able to analyze and treat any acoustical problems. You'll spend more money than DIY, but it would "git 'er done" quickly without reading a lot of forum threads.



I'd have worded that a bit differently.


An audio-calibrator such as UMR's technique is to use your existing room and your existing stereo-store equipment, possibly recommend additional existing stereo-store equipment (PEQ, feedback destroyers, etc) or replacement stereo-store equipment (blown speakers, bad cable), possibly moving the couch, and get the best sound with that. Similar to the sencore link I made above.


Then there's acoustic consultants like Terry Montlick who do that as well, but they focus more on changing the room, especially the room boundaries, with absorption and diffusion, to get even better sound than an audio-calibrator.


The latter being more about what this thread is about.


The former being

a) pretty good (worth the cash, noticable improvement) from the various reviews of UMR's work that I've read posted here

b) perhaps really what traveler wants, given the WAF comment in the above post.


IMO, for DIY, one should look at what's coming out of their existing hardware first (check for miswiring, blown drivers, etc) because if your existing system is unfaithful, then that's your biggest bang for the buck to get it fixed, before acoustical tweaks are applied.


----------



## BasementBob

Traveler:


I'm not suggesting you should do these things, even if my wording/phrasing is strong. This is just the first things I thought of when I looked at your room.



> Quote:
> Yup, that's the stuff [Tectum]. It's actually designed to eliminate sound transmission through the wall, which is not what I'm trying to do. But, will it still work for reducing audio reflection? I don't know. The mounting directions also seem to be for reduction of sound transmission.



I believe it's only for reducing audio reflection, and not for 'eliminate sound transmission through a wall'.



> Quote:
> Would it really do any good to fir out the tectum with fiberglass behind it for my application?



Whether you need more absorption/diffusion is another question.



> Quote:
> Now, regarding your second post, Yes, I have a computer and I certainly can get a mic/preamp and mic stand (the Media Resource Center reports to me ) and I have a sound level meter.



Have a look through http://www.etfacoustic.com/ 

RplusD (at that website) is a tool that you can use with your computer to find out what's going on. But it's just a tool it won't tell you what's going on. i.e. you have a hypothosis you want to test, you can set up experiments and use this tool to gather data to prove/disprove that hypothosis. The trick is knowing enough acoustics to use the tool successfully -- it's not that hard, but you won't do it by Monday. (BTW, you might get your computer's sound card to work, but I suggest the USB SoundBlaster is a lot easier to get RplusD to work with.)

I've used it like this
http://www.bobgolds.com/SpeakerTests/ 
http://www.bobgolds.com/CornerTrap/20040627/home.htm 
http://www.bobgolds.com/CornerTrap/20040627/compare.htm 

There are other software that do the same thing -- There's a good list somewhere.


I suspect you'll be happy with UMR, but given your job you might enjoy these books
Master Handbook of Acoustics by F. Alton Everest 
How to Build A Small Budget Recording Studio From Scratch : With 12 Tested Designs by Michael Shea 

both of which are easy to read and contain lots of stuff.



> Quote:
> Yes I have Star Wars 1. No, I can't turn the speakers at all. However, once I get the room cleaned-up accoustically I plan on replacing the Left, Right, and center speakers and the L&R will be freestanding towers.



The pod race is a good test of imaging -- at least if you've heard it in a place that has good imaging and know what to listen for. There's probably better tests, but it's one that I personally found a difference with (left speaker to right wall reflection made an acoustical imaging mess in my home).

Consider rushing out and buy a copy of Mission To Mars (2000) before buying a new set of speakers. At the beginning of chapter 11 from "Mission to Mars" where the guy's voice pans around the room is excellent for front-vs-rear timbre testing. I have "driver matched" speakers, yet my surrounds are quite a bit different than my mains. Fortunately my front three mains are identical (same model#, not a 'horizontal center'). Anyone with a 5.1 or 7.1 system should really try this at least once. It's an easy eye opener.



> Quote:
> The front wall does not have open cupboards (unless I removed the doors, but why would I want to do that?)



Not remove the doors; add doors or fill it with fiberglass. It looked to me like the top left cupboard was open (without door). Turn your stereo on and listen, then put your head in a 2'x2'x2' cardboard box and the same music sounds different. I believe the effect is reciprical, especially near the speaker. The effect is probably minor, but worth testing for I think. (It would be major if you had your speaker inside of a slightly larger cupboard, but you're not doing that.)


pi loading. By putting your main speakers into the front wall enclosure, what you've done is called 'baffle' mounting or 'soffet' mounting. Which is ok if your speakers were designed for it, or you've made adjustments. High frequency sound (1000hz +) is directional, mostly beaming straight out from your speaker. Low frequency sound (100hz -) is omnidirectional, going out in every direction from your speaker. Speaker manufactuers know this, and build their speakers assuming they will be out from the wall, and balance the energy between the tweater and woofer so that you get an even amount of sound from each at your listener position. If you put the same speaker against the wall (2pi loading) then the wall will have little effect on the HF, but will almost double the energy radiated forward in the LF due to the wall reflection, giving a boomy sound. Setting your mains to 'small' or other EQ may help.


3pi loading. This is similar to the above, except in addition to a single wall (as with your center), you now are in a corner (2 walls), giving an even larger bass boost.


Then there's off axis frequency response. Speakers sound different depending on the angle to which you are listening. The best is when the speaker is pointed right at you. But it changes timbre off center (off axis, left or right some degrees). The SpeakerTests link, about 70% of the way down, has some good/good/good/bad/bad/bad examples of off axis.

Anyway, becuase your left/right are

a) pointed straight out from the front wall, and

b) right against the side walls

you're probably more sensitive than most to off axis performance (comb filtering), and may benefit from a side wall absorber or toe-in (which is why I asked if you could turn your left/right mains).


BTW, I hope the top of your couch is shoulder level or shorter -- nothing near your ears. Looks like it is. But your 4 front seats look higher.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/12504992
> 
> 
> Pepar:
> 
> 
> 
> I'd have worded that a bit differently.
> 
> 
> An audio-calibrator such as UMR's technique is to use your existing room and your existing stereo-store equipment, possibly recommend additional existing stereo-store equipment (PEQ, feedback destroyers, etc) or replacement stereo-store equipment (blown speakers, bad cable), possibly moving the couch, and get the best sound with that. Similar to the sencore link I made above.
> 
> 
> Then there's acoustic consultants like Terry Montlick who do that as well, but they focus more on changing the room, especially the room boundaries, with absorption and diffusion, to get even better sound than an audio-calibrator.
> 
> 
> The latter being more about what this thread is about.
> 
> 
> The former being
> 
> a) pretty good (worth the cash, noticable improvement) from the various reviews of UMR's work that I've read posted here
> 
> b) perhaps really what traveler wants, given the WAF comment in the above post.



My exchange was with jjacknife, not traveler, who seems to be on a different arc. jjacknife's post was simply "I may need to look into a professional calibration before i frustrate myself!"


----------



## traveler




> Quote:
> Originally Posted by *BasementBob* /forum/post/12505361
> 
> 
> Traveler:
> 
> 
> I suspect you'll be happy with UMR, but given your job you might enjoy these books



I've exchanged several messages with UMR and may have them do some work next summer.



> Quote:
> Master Handbook of Acoustics by F. Alton Everest
> How to Build A Small Budget Recording Studio From Scratch : With 12 Tested Designs by Michael Shea
> 
> both of which are easy to read and contain lots of stuff.



I have the first one but it's been several years since I read it. Also, since I have a 60 hr/wk job AND volunteer my time as a pastor of a local church, I don't have a lot of free time (or cash) and most of it (both time and spare cash) is spent in the theater room. I was hoping to find here something that I could do fairly quickly without it becoming a major project.



> Quote:
> The pod race is a good test of imaging -- at least if you've heard it in a place that has good imaging and know what to listen for. There's probably better tests, but it's one that I personally found a difference with (left speaker to right wall reflection made an acoustical imaging mess in my home).
> 
> Consider rushing out and buy a copy of Mission To Mars (2000) before buying a new set of speakers. At the beginning of chapter 11 from "Mission to Mars" where the guy's voice pans around the room is excellent for front-vs-rear timbre testing.



I have a 7.1 system (Lexicon MC-12B] and am amazed at the LtoR and front to back imaging I already have. In fact the first time we watched Independence Day as the coke can was shot off the spaceship and bounced around the room only to land in the right rear, both my wife and I actually turned our heads. My current concern is that the fronts sound muddy and I don't think the imaging is right so I will get a copy of Mission to Mars and check it out.



> Quote:
> pi loading. By putting your main speakers into the front wall enclosure, what you've done is called 'baffle' mounting or 'soffet' mounting. Which is ok if your speakers were designed for it, or you've made adjustments. High frequency sound (1000hz +) is directional, mostly beaming straight out from your speaker. Low frequency sound (100hz -) is omnidirectional, going out in every direction from your speaker. Speaker manufactuers know this, and build their speakers assuming they will be out from the wall, and balance the energy between the tweater and woofer so that you get an even amount of sound from each at your listener position. If you put the same speaker against the wall (2pi loading) then the wall will have little effect on the HF, but will almost double the energy radiated forward in the LF due to the wall reflection, giving a boomy sound. Setting your mains to 'small' or other EQ may help.
> 
> 
> 3pi loading. This is similar to the above, except in addition to a single wall (as with your center), you now are in a corner (2 walls), giving an even larger bass boost.



Personally, I would never have put the speakers in the front cabinetry. Unfortunately, that's how it was when we bought the house. At the time it was open to the remainder of the basement and we simply enclosed the room to provide complete light control. I will try setting the cross-over on the fronts to a much higher point and see if that makes any difference (the Lexicon allows a lot of control of this).



> Quote:
> Anyway, becuase your left/right are
> 
> a) pointed straight out from the front wall, and
> 
> b) right against the side walls
> 
> you're probably more sensitive than most to off axis performance (comb filtering), and may benefit from a side wall absorber or toe-in (which is why I asked if you could turn your left/right mains).



That's kind of what I was thinking. And, why I was considering doing a 3 ft high strip of Tectum from the front wall to the back at the top of the wains coat. I could cover it with material and still maintain (perhaps even improve) the WAF.



> Quote:
> BTW, I hope the top of your couch is shoulder level or shorter -- nothing near your ears. Looks like it is. But your 4 front seats look higher.



Yep, we have direct access from all speakers to our ears when sitting on the couch (double recliner, too). The smaller chairs are for when guests come over. My wife and I, along with any children of our friends sit on the "floor rockers" while the guests sit in the sweet spot.


Thanks for your input. For now I think I will run the Tectum as I have described as well as on the entire rear wall and enclose the one open cupboard on the top left corner of the front and see what I end up with.


----------



## umr




> Quote:
> Originally Posted by *BasementBob* /forum/post/12504992
> 
> 
> Pepar:
> 
> 
> 
> I'd have worded that a bit differently.
> 
> 
> An audio-calibrator such as UMR's technique is to use your existing room and your existing stereo-store equipment, possibly recommend additional existing stereo-store equipment (PEQ, feedback destroyers, etc) or replacement stereo-store equipment (blown speakers, bad cable), possibly moving the couch, and get the best sound with that. Similar to the sencore link I made above.
> 
> ....



I am an acoustic consultant as well as a calibrator. I am a degreed engineer unlike most in my craft.


----------



## BasementBob

Umr:


----------



## caesar1

I'm trying to decide how to acoustically treat my existing room (see my signature link to room photos).


I keep reading about traps and absorption, but little on diffusion.


I've also checked out a few sites from companies that post in this thread who sell acoustical treatments (which is probably the way I'll be going, since I'm not a DIY guy). It seems like bass traps are everywhere on all those sites (many different kinds), with little mention or discussion of diffusion.


The basic method of treatment seems to be absorption/traps in the corners and at the first reflection points.


But what if you have dipole side surrounds (actually bipole/dipole)? Shouldn't the concern for dipole surrounds be diffusion -- to spread out sound coming from them as much as possible?


I'm concerned about putting up a bunch of traps/absorbers; but then lessening the effects from my dipole side surrounds.


So what do people do who use dipoles/bipoles?


----------



## txredneckbud

Here is an odd request.


What would happen accoustically if someone wanted to cover their accoustic panels with cowhide? Would it affect absorbtion? Too much? The purpose of the cowhide is obviously from an interior design perspective and desire.


Is it a big no no? Any technical input would be GREATLY appreciated.


----------



## Terry Montlick

Huge no-no. Don't even think about it.










Regards,

Terry


----------



## txredneckbud

Terry, I thought that might be the case. Is the reason because the cowhide doesnt have the right absorbtion quality? Does it reflect more or something? Thanks, just trying to understand more.


I assume if the customer wanted cowhide accents they could simply put it elsewhere whereby it is not a part of the acoustical treatment.


----------



## Terry Montlick

It reflects a lot of mid to high frequency sound, so you are undoing much of the benefit of using an efficient panel absorber material (semi-rigid fiberglass).


Regards,

Terry


----------



## txredneckbud

Ter, thanks bud, got it.


----------



## Ethan Winer




> Quote:
> Originally Posted by *caesar1* /forum/post/12526855
> 
> 
> It seems like bass traps are everywhere on all those sites (many different kinds), with little mention or discussion of diffusion.



Diffusion is more like icing on the cake, where absorption is an important staple. Also, good diffusion costs a lot more than good absorption, so when push comes to shove and folks see the price tag, they often opt for more absorption than a less-capable mix of both. But when "excellent" is more important than "cheap," diffusion is a great choice.



> Quote:
> Shouldn't the concern for dipole surrounds be diffusion -- to spread out sound coming from them as much as possible?



Probably not. Some of this is taste, and my preference is to absorb the rear radiation of L/C/R dipoles, and use diffusion only on the rear wall behind you when listening.



> Quote:
> I'm concerned about putting up a bunch of traps/absorbers; but then lessening the effects from my dipole side surrounds.



I'd say the same applies there too, as least so far as early reflections are concerned. You really want to kill those reflections completely, versus scattering them around the room. But it also depends on the size of the room. A large room has much more leeway for diffusion than a small room.


--Ethan


----------



## caesar1




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/12538500
> 
> 
> Diffusion is more like icing on the cake, where absorption is an important staple. Also, good diffusion costs a lot more than good absorption, so when push comes to shove and folks see the price tag, they often opt for more absorption than a less-capable mix of both. But when "excellent" is more important than "cheap," diffusion is a great choice.
> 
> 
> 
> 
> Probably not. Some of this is taste, and my preference is to absorb the rear radiation of L/C/R dipoles, and use diffusion only on the rear wall behind you when listening.
> 
> 
> 
> 
> I'd say the same applies there too, as least so far as early reflections are concerned. You really want to kill those reflections completely, versus scattering them around the room. But it also depends on the size of the room. A large room has much more leeway for diffusion than a small room.
> 
> 
> --Ethan



Thanks for the comments. I have some follow-up questions.


What's considered a "large" room. My room is 16 x 20 (7' 9" ceiling).


As far as dipole side surrounds (I don't have dipoles anywhere but the sides) -- I thought the point of them was to reflect the sound off the front and rear walls (as opposed to firing directly at the listener), to create an immersive diffuse sound.


So, with that in mind, if you have absorption that effects those reflections, won't that lessen the side surround sound effects? Or am I not understanding absorption? In my mind, it sounds like the sound from the side surrounds would be swallowed up, instead of the reflections reaching the listener as intended.


----------



## pepar




> Quote:
> Originally Posted by *caesar1* /forum/post/12538576
> 
> 
> Thanks for the comments. I have some follow-up questions.
> 
> 
> What's considered a "large" room. My room is 16 x 20 (7' 9" ceiling).
> 
> 
> As far as dipole side surrounds (I don't have dipoles anywhere but the sides) -- I thought the point of them was to reflect the sound off the front and rear walls (as opposed to firing directly at the listener), to create an immersive diffuse sound.
> 
> 
> So, with that in mind, if you have absorption that effects those reflections, won't that lessen the side surround sound effects? Or am I not understanding absorption? In my mind, it sounds like the sound from the side surrounds would be swallowed up, instead of the reflections reaching the listener as intended.



With the exception of the first reflection point on the rear wall, they are all in the front of the room. Obviously, the panels in the front will absorb sound from the dipoles, but not until it has become part of the reverberant room sound. Your sense of envelopment won't be degraded.


----------



## caesar1




> Quote:
> Originally Posted by *pepar* /forum/post/12540617
> 
> 
> With the exception of the first reflection point on the rear wall, they are all in the front of the room. Obviously, the panels in the front will absorb sound from the dipoles, but not until it has become part of the reverberant room sound. Your sense of envelopment won't be degraded.



When you say they are all in the front of the room, are you excluding bass traps? As I have read that it is a good idea to put bass traps in all 4 room corners.


----------



## pepar




> Quote:
> Originally Posted by *caesar1* /forum/post/12542394
> 
> 
> When you say they are all in the front of the room, are you excluding bass traps? As I have read that it is a good idea to put bass traps in all 4 room corners.



OK, I see your point. Bass traps in the rear corners will absorb some of the side dipole surround sound. Clearly, there are competing goals at play in maximizing the home theater experience and I'm not sure that there is a universal strategy that will bring them all into harmony. From my experience, limited as it is to my theater (see link in my sig) and those of some fellow local A/V enthusiasts, effectively treating the frequencies below - say - 500Hz is a primary goal and when done right _greatly_ improves every aspect of the sound of one's theater. Perhaps you could start with traps at the three junctures in the front and see if that provides the necessary trapping?


If you are going to DIY this, then you should consider getting some acoustical analysis software and a calibrated microphone which will allow you to test, add treatments and test again. And listen.


You can ask a lot of questions here and get nearly universally good advice but, short of a pro coming in and testing your room and making recommendations, no one here can tell you with any degree of certainty to place these here and those there and you're good to go.


Have fun!


----------



## caesar1




> Quote:
> Originally Posted by *pepar* /forum/post/12543756
> 
> 
> If you are going to DIY this, then you should consider getting some acoustical analysis software and a calibrated microphone which will allow you to test, add treatments and test again. And listen.



I am definitely not going to DIY. In fact, I'm concerned about my ability to correctly hang an acoustical panel that I purchase from one of the companies in this thread.


My goal is to at least do the minimum treatment for my room (which currently has none).


----------



## pepar




> Quote:
> Originally Posted by *caesar1* /forum/post/12544191
> 
> 
> I am definitely not going to DIY. In fact, I'm concerned about my ability to correctly hang an acoustical panel that I purchase from one of the companies in this thread.



They're going to hang them for you?











> Quote:
> My goal is to at least do the minimum treatment for my room (which currently has none).



If you are not DIY'ing and using the virtually free software available or paying a pro to come in and measure, you really should be minimalist about it. More can be added later if necessary. It is very easy to over-dampen a small room, so stick with "right-sized" 2" OC 703 (or equiv) at first reflection points. And bass traps at the three front junctures. Most of the vendors lurking on this thread can supply bass traps that are, basically, a 2x4 panel of 2" OC 703 that will straddle the corner. You will be MUCH further ahead if you can fill the cavity behind the panel with the same material. gik, I believe, sells material to do this. Maybe the others as well.


If you can afford it, before doing the above, I urge you to call in a pro with the proper test gear to check for room "issues" that the above basics will not fix.


Just my $.02.


----------



## caesar1




> Quote:
> Originally Posted by *pepar* /forum/post/12546638
> 
> 
> 
> It is very easy to over-dampen a small room, so stick with "right-sized" 2" OC 703 (or equiv) at first reflection points.



I see "large" and "small" rooms referenced alot. However, what is the definition of a "large" or "small" room. I'm not sure where my room fits in at 16 x 20 (7' 9" ceiling). Is that considered "small"?



> Quote:
> Originally Posted by *pepar* /forum/post/12546638
> 
> 
> 
> And bass traps at the three front junctures. Most of the vendors lurking on this thread can supply bass traps that are, basically, a 2x4 panel of 2" OC 703 that will straddle the corner. You will be MUCH further ahead if you can fill the cavity behind the panel with the same material. gik, I believe, sells material to do this.



It looks like Gik has these tri corner things that sit on the floor and actually take up the whole corner (triangle shaped columns). Maybe one of each of those in each of the front corners as a minimum -- and I won't need to hang them on the wall (so even I can do that install).


----------



## Ethan Winer




> Quote:
> Originally Posted by *caesar1* /forum/post/12538576
> 
> 
> What's considered a "large" room. My room is 16 x 20 (7' 9" ceiling).



I'd call that a medium size room, but in "acoustics talk" pretty much any room you'll find in a typical home is considered small. To acousticians, a large room is an auditorium.



> Quote:
> As far as dipole side surrounds (I don't have dipoles anywhere but the sides) -- I thought the point of them was to reflect the sound off the front and rear walls (as opposed to firing directly at the listener), to create an immersive diffuse sound.



I don't have any direct experience with dipoles used for surrounds. I am not a fan of having surrounds bounce sound around the room intentionally anyway. That may be useful in a movie theater, but that's not what I'd want in my living room. I prefer "normal" speakers pointed at the main listening position as defined in the Grammy surround standards.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *caesar1* /forum/post/12546729
> 
> 
> I see "large" and "small" rooms referenced alot. However, what is the definition of a "large" or "small" room. I'm not sure where my room fits in at 16 x 20 (7' 9" ceiling). Is that considered "small"?



Yes, most rooms in a residence are going to be "small." I say most because I have a 20x30x18 "great room" that, if turned into a theater (over my wife's dead body) would still not be considered "large" - think auditorium - but would not have the problems of my "small" 13x21x8 home theater.



> Quote:
> It looks like Gik has these tri corner things that sit on the floor and actually take up the whole corner (triangle shaped columns). Maybe one of each of those in each of the front corners as a minimum -- and I won't need to hang them on the wall (so even I can do that install).



That's exactly the product I was thinking about having seen it at a show a few months ago.


----------



## ccapozzoli

I have some questions regarding my room absorbtion. If you click on the link and you will see my room.


I am going to use 2" OC703 on the side walls covered with GOM fabric and the front stage I am going to use 1" lincoustics again with GOM black fabric.


Now for the back wall, I was thinking of using Tectum panels becasue I happen to have some. However, should I just continue with the 703 on the bacl wall or will the Tectum panels better absorb and also diffuse the sound.


You can post your replies to my thread or this thread, Thank you

http://www.avsforum.com/avs-vb/showt...3#post12547443


----------



## bpape

I'd agree Pepar. To really start to treat a room based on 'large room' theory, it's a lot bigger than a normal residential space.


Bryan


----------



## Ethan Winer




> Quote:
> Originally Posted by *ccapozzoli* /forum/post/12549007
> 
> 
> I have some questions regarding my room absorbtion. If you click on the link and you will see my room.



I'd use at least two-inch thick 703 everywhere, including the front wall, and at least four inches thick near all corners. I don't have the specs in front of me for Tectum, but as I recall that stuff is more like ceiling tiles than 703.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/12556670
> 
> 
> I'd use at least two-inch thick 703 everywhere, including the front wall, and at least four inches thick near all corners. I don't have the specs in front of me for Tectum, but as I recall that stuff is more like ceiling tiles than 703.



Not really EVERYWHERE?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/12556871
> 
> 
> Not really EVERYWHERE?



Yeah. He kinda walks funny.


----------



## GsHTPC

Looking for links on DIY bass corner traps. I saw a corner trap where someone just cut OC 705 into 24" triangles Not sure what type of triangles and then just stacked them all the way up. Looking for that post or similar post to get ideas for my room.


I found a local dealer that had a carton of OC 705 2'by48" and wanted to use that to cut some triangles and place them in the corners. My questions are around how to hide them.


----------



## GsHTPC

Looking for links on DIY bass corner traps. I saw a corner trap where someone just cut OC 705 into 24" triangles Not sure what type of triangles and then just stacked them all the way up. Looking for that post or similar post to get ideas for my room.


I found a local dealer that had a carton of OC 705 2'by48" and wanted to use that to cut some triangles and place them in the corners. My questions are around how to hide them.


----------



## yngdiego




> Quote:
> Originally Posted by *GsHTPC* /forum/post/12564446
> 
> 
> Looking for links on DIY bass corner traps. I saw a corner trap where someone just cut OC 705 into 24" triangles Not sure what type of triangles and then just stacked them all the way up. Looking for that post or similar post to get ideas for my room.
> 
> 
> I found a local dealer that had a carton of OC 705 2'by48" and wanted to use that to cut some triangles and place them in the corners. My questions are around how to hide them.



I did this very thing a few weeks ago for all four corners. I must say, it turned out very professional. I attached a picture.


Basically what I did was get 1/2" plastic corner molding from Home Depot and placed a floor to ceiling strip on both sides of the corner trianges. I got it tight enough that it held the chunks in place. I think got GOM fabric and used industrial velcro to stretch it across corner. I then got a quarter round molding, painted it wall color, and pushed it against the edges to hide the fabric.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12564539
> 
> 
> I did this very thing a few weeks ago for all four corners. I must say, it turned out very professional. I attached a picture.
> 
> 
> Basically what I did was get 1/2" plastic corner molding from Home Depot and placed a floor to ceiling strip on both sides of the corner trianges. I got it tight enough that it held the chunks in place. I think got GOM fabric and used industrial velcro to stretch it across corner. I then got a quarter round molding, painted it wall color, and pushed it against the edges to hide the fabric.


_Very nice!_


----------



## eugovector




> Quote:
> Originally Posted by *yngdiego* /forum/post/12564539
> 
> 
> I did this very thing a few weeks ago for all four corners. I must say, it turned out very professional. I attached a picture.



Very nice, please post more pictures, room dimensions, etc. This room looks like an excellent example or a small, simple, yet great theater.


----------



## BasementBob

Superchunk corner traps basic intro:
http://www.bobgolds.com/TrapHarder/home.htm 


Cut patterns
http://forum.studiotips.com/viewtopic.php?t=535 


yngdiego - you've done a nice finishing job (above).


----------



## GsHTPC

Looks great. I just figured out that I need twice as much OC 705 material that I had thought. I wanted to do 24" triangles but I can get 8 pieces out of each 24x48" so I figured the entire box will only go abour 84" and I need 95" per cornoer. I'll need to buy 1 and 1/2 more box's of that.


Do you have an pictures pre construction? It would be great to see how it all went together. The finished product looks great.


----------



## yngdiego




> Quote:
> Originally Posted by *GsHTPC* /forum/post/12566358
> 
> 
> Looks great. I just figured out that I need twice as much OC 705 material that I had thought. I wanted to do 24" triangles but I can get 8 pieces out of each 24x48" so I figured the entire box will only go abour 84" and I need 95" per cornoer. I'll need to buy 1 and 1/2 more box's of that.
> 
> 
> Do you have an pictures pre construction? It would be great to see how it all went together. The finished product looks great.



No I don't have any pre-construction or in-progress pictures. I got 8 triangles from each piece and ended up using an extra piece or two since the weight of the pile compressed the OC703 a bit and I didn't want a gap at the ceiling.


Also, I got a $12 electric turkey carving knife at wal-mart which cut them like butter. DO get a high-quality breathing mask, wear long sleeves, jeans, and I taped around my wrists and neck to keep out stray fibers, in addition to wearing double gloves (rubber and cloth).


For the side and cloud panels I got some resin at HD and dabbed it along the edges to give it some rigidity.


----------



## nathan_h

Is there any reason to not use "speaker grill cloth" like this:

http://www.parts-express.com/pe/show...number=260-335 


instead of GOM fabric to cover a bass trap?


----------



## eugovector




> Quote:
> Originally Posted by *nathan_h* /forum/post/12572083
> 
> 
> Is there any reason to not use "speaker grill cloth" like this:
> 
> http://www.parts-express.com/pe/show...number=260-335
> 
> 
> instead of GOM fabric to cover a bass trap?



I think you'll find that speaker grill fabric is too fine and loose of a weave. You'll be able to see the color of the insulation underneath, it will tear more easily, and stray fiberglass fibers may get out.


----------



## bpape

You can use black Muslin behind the grille cloth to cover the color. It's all cotton and will be fine in that application. You can't use it in front of speakers though.


Bryan


----------



## hdmIII

I just finished my basement theater room and I really need some advice. My room is 12'w x 22'L x 7.4'H. I have the RBH T2 speakers for L/R front and a smaller mtm for center. I have the front corners filled with some 703 , then some 1" lineacoustic panels on one side wall from floor to ceiling and 6 feet wide,and 1, 703 panel on the other wall (until I get some more.) with the subs off I get clear center info but with the subs on I get muddiness and a peak somewhere in the midrange.

Any suggestions will be greatly apreciated.

Thanks


----------



## bigeric

This is a great site and has answered many of my questions as I get ready to build my basement theater.


I've found discussion about potential resonance problems but haven't been able to find a recommendation from the Pros (Dennis, Brian, ...).


What is the proper air gap between concrete walls and stud walls to reduce sound and bass transmission without creating a resonance problem?


Thanks in advance,

Eric


----------



## VA HDman




> Quote:
> My room is 12'w x 22'L x 7.4'H. I have the RBH T2 speakers for L/R front and a smaller mtm for center. I have the front corners filled with some 703 , then some 1" lineacoustic panels on one side wall from floor to ceiling and 6 feet wide,and 1, 703 panel on the other wall (until I get some more.) with the subs off I get clear center info but with the subs on I get muddiness and a peak somewhere in the midrange.



WOW-- T-2s in a room that size can probably cause permenant hearing loss.







My HT is a very similar demension. I was seriously considering the T-2s but opted for the RBH SI-6100s instead. I'd be interested in how you like them once you get the accoustics straighted out. In that regards, you should PM Bryan (Bpape). He is "the man" when it comes to DIY HT accoustics. Very knowledgable on HT set-up and has reasonably priced accoustic materials.












> Quote:
> What is the proper air gap between concrete walls and stud walls to reduce sound and bass transmission without creating a resonance problem?



I used isolation clips to decouple the wall framing from the cement foundation. I also used these clips to decouple my walls from the overhead floor trusses. It maintains about an 1.5" gap.

http://www.pac-intl.com/decoupled.htm 


On the ceiling I used a different style isolation slip. IMO these seem to work better when the load is completely vertical becuase the isolation rubber is below the load.

http://www.kineticsnoise.com/arch/isomax/index.aspx 


If you are serious about sound isolation, I would also recommend using double 5/8" sheet rock with 3 tubes of green glue between each sheet.







[Note: use double sheet rock on both sides of all interior walls-- those that do not back up to the cement foundation.]


Good luck. Take your time -- plannning is the most important phase of HT construction.


----------



## Hiller131

Hey guys,


I have been searching through the forum and can't find an answer to this one... I'm building out my basement like everyone else seems to be and I'm going to go with the GOM/Linacoustic pairing. If I'm not worried about sound bleed-through to other rooms in the basement is it necessary to put up drywall? All the construction threads seem to have drywall but I'm assuming it's only necessary for sound isolation purposes.


Thanks,

Steve


----------



## VA HDman

It's unclear what you mean. You indicate there will be "other rooms" in the basement. How will these be created if you don't have sheetrock walls (i.e., what kind of wall will you have)? Can you explain? Better yet, do you have any drawings of your layout?


----------



## Hiller131

I sorry if I wasn't clear...unfortunately, I don't have a floorplan on the computer yet to be able to share with you guys. Basically what it comes down to is I have already put up standard 2x4 walls. In any normal room drywall would then be attached, you paint, and you are done. What is usually done around here for a theater is drywall, then linacoustic, then acoustically transparent fabric over all that. That I was trying to ask was is does the drywall serve some purpose acoustically for the theater?


Hope that is a little more clear...if it's not I'll start another thread with floor plans and stuff.


Thanks

Steve


----------



## Dennis Erskine




> Quote:
> What is the proper air gap between concrete walls and stud walls to reduce sound and bass transmission without creating a resonance problem?



Anytime you have air movement in a confined space, you'll have resonance ... you just want the resonance to be inaudible. The issue of more importance however, is that the size of the air gap is going to be dictated by local building and fire codes. Typically, you'll find the framing is 1/4 to 1/2" from the foundation walls and a part of this reason is many foundation walls are not straight! Fiberglass insulation is installed between the studs appropriate to the studs you're using (2x4 or 2x6). Now, that remaining air gap will have to be closed. At a minimum at the top of the walls. In some areas, insulation will have to be placed between the back of the stud and the foundation wall (fire code).



> Quote:
> IMO these seem to work better when the load is completely vertical becuase the isolation rubber is below the load.



Actually, makes no difference.


----------



## VA HDman

Hiller


As long as you are not concerned about sound being tranmitted into the adjacent rooms (including the rooms upstairs), your "standard" 2x4 sheetrock walls will work fine. You will still need to do the treatment inside the room to address the accoustics issues there.


----------



## VA HDman

Dennis,


According to the marketing material issued by PAC, you are correct the positioning of the PAC isolation clip should not make any difference.










I was just giving my own personal opinion. I have used both types of isolation clips. I prefer the Kinetic clips for the ceiling and the PAC clips for the walls. If you look closely at the PAC clip it has a metal collar inside the rubber pad, which connects the rubber to the metal frame of the clip. When the clip is nailed or screwed into an overhead floor truss the rubber pad is pointed upward and the weight of the ceiling is pulling downward. The main contact point for the load is located between the nail/screw head and the metal bracket. IMO the rubber pad will not be very effective, unless it was significantly compressed during the install. [In addition, I don't think the metal collar will allow significant compression.] With the Kinetics clip the isolation rubber is located on both the top and bottom of the hat channel. I doesn't matter if the force is downward or upward -- the rubber should minimize and vibration. The Kinetic clip also has a higher load rating, which is important when you are installing two layers of rock on the ceiling.


----------



## bpape




> Quote:
> Originally Posted by *VA HDman* /forum/post/12615586
> 
> 
> Hiller
> 
> 
> As long as you are not concerned about sound being tranmitted into the adjacent rooms (including the rooms upstairs), your "standard" 2x4 sheetrock walls will work fine. You will still need to do the treatment inside the room to address the accoustics issues there.



I would respectfully disagree. From a performance standpoint, sound getting IN to the room is much more of a concern in order to keep the noise floor as low as possible.


Bryan


----------



## Dennis Erskine

Bryan makes an excellent point. Sound Isolation is NOT to avoid waking the family. The lowest sound level on a movie is 22dB. The average noise floor in an urban (quiet) residence is 30-33 dB. Let's look at the impact of this two ways:


(1) If you set your reference level to 74 db, you'll need to set it for 82 (min) to hear the entire sound track. The problem with that, is the 115dB peaks will be 123 dB and it is very likely that neither your speakers, your amplifiers, or your ears will handle that.


(2) Each 3dB is a doubling of energy. So, from 22 to 25, you have 2 times. From 22 to 28 is four times, and from 22 to 31 is eight times louder.


Don't think you really want that. If fact, once you do that, you'll find the sound isolation you didn't think you'd need, you need ... or your wife will want the lawn mowed and the snow shoveled (at the same time, of course).


----------



## VA HDman

My bad -- I agree with Bryan and Dennis. I wasn't considering the noise outside the HT. If you are going for a reference sound level inside the HT, or if you have any significant noise outside the HT you clearly need to address sound isolation issues.


----------



## cheron1701

The all important WAF has appeared when it comes to putting up acoustic treatments in the still being born home theater. Has anyone used this before and/or is it okay or does the suede defeat whatever purpose the acoustic panels might serve. I am planning on 2" first reflection points along with a diffuser in the back. I will probably order some corner traps from GIK along with it. Any thoughts would be appreciated.


----------



## bigeric




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/12614598
> 
> 
> ... Anytime you have air movement in a confined space, you'll have resonance ... you just want the resonance to be inaudible. ...



You've hit on what I was asking about. Based on all the posts I've read, for double walls, it seems that the air cavity depth that you recommend 9 inches (3.5 + 2 + 3.5).


Assuming that I get the fire-stopping right, what's the air cavity depth that I need against a concrete wall for the resonance to be inaudible? (3.5 + ??? + concrete wall) I've searched for a formula or guideline to calculate the resonant frequency and haven't been able to find one.


Thanks for all the great information on this site!


Based on all that I've found here, I'm going to build double walls on the two walls that aren't against the concrete walls. I'm going to do room-within-a-room for the ceiling by running separate ceiling joists, supported by the walls, in between the existing joists. That seems to me to be easier and cheaper than RSIC clips.


Eric


----------



## Terry Montlick




> Quote:
> Originally Posted by *bigeric* /forum/post/12665563
> 
> 
> I've searched for a formula or guideline to calculate the resonant frequency and haven't been able to find one.



This is called the mass-air-mass resonance formula. Here it is for metric units:


f = 1897 √(m1 + m2) / √(D m1 m2)


f is resonant frequency in Hz, m1 and m2 are masses densities of the two wall leaves in kg/m^2, and D is their distance in mm.


Regards,

Terry


----------



## VA HDman

Seperate ceiling joists supported by the interior walls may actually perform better than the isolation clips for the ceiling.


Since it appears you are wanting to maximize your sound isolation, here are a few additional issues you may wish to consider:


How are you going to suport your interior walls? If you make a hard connection to the existing ceiling joists you'll be defeating the whole purpose of the "room within a room" concept. I have used the PAC isolation clips (link above) to isolate the walls in front of the concrete foundation and the inner wall of my double interior walls. I didn't use the isolation clips on the exterior double wall since it was going to make a hard connection to the sheetrock in the room adjacent the HT. Based on my review, double walls on 24" centers performed a little better than those on 16" centers.


Keep in mind, you'll probably want to install communicating doors in the double wall (i.e., two seperate solid wood or metal doors opening in opposite directions) otherwise the double wall will have a significant weak spot. You'll want heavy doors with a very good seal -- more mass = less sound transmission. They sell sound proof doors ($3000 each) -- I went with two exterior grade solid wood doors with full weather seals. You can get these for about $350 each at Lowes or HD. When ordering, keep in mind they need to swing in opposite directions. Don't make any hard connections (or anymore than required) between the double walls, especially at the door jams. [Obvioulsy both walls will touch the same slab -- unless you are doing new construction and can make two seperate slabs. Some people install chalk or rubber pad under the sill plate to increase the isolation from the slab.]


I used double 5/8 inch sheetrock with greenglue (3 tubes per sheet) everywhere! Some folks will say that the two layers should be of different thicknesses to reduce the harmonic vibrations. I spoke with the folks at Greenglue. They recommended two layers of 5/8". I heavlily chalked all of the seams on the initial layer of sheetrock and didn't mounted any electrical boxes in walls. They were all mounted in the columns, riser, stage, soffit or just surface mounted (i.e., behind the AT screen). This helps keep the number of wall penertrations down to a minimum -- basically the only pentrations are for wires and conduit for future wires. If you go with recessed lights, you'll want to install them in a soffit -- this way you will not make any holes in your ceiling.


Are you going to install a floating floor insdie the HT? I didn't. Instead I used isolation pads to decouple the riser from the slab and walls. I used GG between the two layers of plywood on the stage and riser. I have a very heavy pad under the carpet. I install isolation pads under my front row of Berkline. I installed three layers of 30# roofing felt under the stage and then filled the entire stage with (clean and dry) sand.


You'll also want to consider your HVAC and ventilation issues carefully.


Hope this helps.


----------



## Dardog

I am about to mount my linacoustic on my walls. I had planned to cover the full front and then the sides to a height of 44", but only in the half where the HT is located ( the room is 38' deep, but I will only place linacoustic in the front 17'). I'm now thinking I can just mount the full width (47"), but might there be a downside to this? The other dimensions on the room are 12.5' wide and 7' tall (it's in the basement).


Thanks,


----------



## Ethan Winer




> Quote:
> Originally Posted by *Dardog* /forum/post/12697869
> 
> 
> I'm now thinking I can just mount the full width (47"), but might there be a downside to this?



That's not my favorite way to treat a room because it covers places that don't need covering and ignores places that do need treatment. Much better is to treat all the corners with as many bass traps as you can manage, and treat the reflection points with absorption at least two inches thick.


--Ethan


----------



## Dardog




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/12706879
> 
> 
> That's not my favorite way to treat a room because it covers places that don't need covering and ignores places that do need treatment. Much better is to treat all the corners with as many bass traps as you can manage, and treat the reflection points with absorption at least two inches thick.
> 
> 
> --Ethan



I forgot to mention that I plan to put base traps in the two corners by the screen. I will also look at putting a base trap in the one rear corner in the room. The other corner is a staggered walkway to a back room.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Dardog* /forum/post/12710668
> 
> 
> I will also look at putting a base trap in the one rear corner in the room. The other corner is a staggered walkway to a back room.



Most rooms have 12 corners!










The more corners you treat, the better. Always.


--Ethan


----------



## Bing

I apologize if this against rules but what should one pay for case of 6 of 2" OC703 (2'x4')? Maybe someone can PM me the answer. I'm in Canada and close to the border. I'm looking for a US dealer to ship to North Dakota to bypass brokerage and duties.


----------



## pepar




> Quote:
> Originally Posted by *Bing* /forum/post/12723135
> 
> 
> I apologize if this against rules but what should one pay for case of 6 of 2" OC703 (2'x4')? Maybe someone can PM me the answer. I'm in Canada and close to the border. I'm looking for a US dealer to ship to North Dakota to bypass brokerage and duties.


 http://www.spi-co.com/


----------



## Bing

Thanks pepar,


You guys buy the unfaced one right?


----------



## eugovector




> Quote:
> Originally Posted by *Bing* /forum/post/12723750
> 
> 
> Thanks pepar,
> 
> 
> You guys buy the unfaced one right?



Unless your using it exclusively for mid and bass trapping. Highs will bounce right off the facing.


----------



## BasementBob

Bing:


This list is out of date, but it's what people posted in the past:
http://www.bobgolds.com/InsulationContractors.htm 


Depending upon what you're doing, you might consider Roxul SafeNSound. Here it's available at Home Depot. It's not rigid, but it's a good density, and it's cheap and available. The 'not rigid' is why I wrote "Depending upon what you're doing".


BTW, you don't have to use 703. Anything from this page with similar absorption coefficients is probably fine.
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## SPDSpappy

I've been searching for more info on icynene here and haven't seen a bang for buck comparison on this vs. fiberglass insulation w/ 2 layers of sheetrock w/ GG in between. Here's the info on icynene from PrarieFoam.com:


Acoustical Properties

(performance in a 2" x 4" wood stud wall @ 125 250 500 1000 2000 4000 Hz. freq.)


STC Sound Transmission Class - 37

19 30 31 42 38 46 (ASTM E-90)


NRC Noise Reduction Coefficient - 70

.11 .43 .89 .72 .71 .67 (ASTM C-423)


Back in post 459, BasementBob said:

"[Icynene] which is an open cell foam with absorbtion, in which case it's fine. Less absorbtion than some other products, but probably better air tight seal."


If the sound insulating properties are almost as good, but icynene is cheaper (considering the cost of another layer of drywall, GG, clips, my own time, etc.), I'd rather pay someone & go w/ icynene. Your thoughts?


----------



## Bing

Basement Bob:


I know about Roxul. I've built several panels out of them. It's effective but too thick visually for HF along side walls. I can't compress it down with a board and allow sound to pass at the same time. I used chicken wire mesh to keep it together but the panels are 4" thick. The rigid boards are much more manageble in terms of keeping flat, cutting to curves, etc. I'd like 2" at primary reflections and maybe 1" towards the back.


----------



## rick11

Can anyone give me some of the best websites to buy acoustic panels. Looking for panels with no fabric (will cover my own) and roughly 2 or 3 by 4 or 5 ft. Am in the Chicago area


thanks!


----------



## pepar




> Quote:
> Originally Posted by *rick11* /forum/post/12777506
> 
> 
> Can anyone give me some of the best websites to buy acoustic panels. Looking for panels with no fabric (will cover my own) and roughly 2 or 3 by 4 or 5 ft. Am in the Chicago area
> 
> 
> thanks!



Usually, once a vendor has made a "panel" they cover it as well. You can take a section of fiberglass and cover it. GIK, I believe, sells "pillowcases" that are used to cover the sections. Size I know about is 2'x4', but there may be others. Glenn (GIK) hangs here. There are (at least) two other vendors here as well - Ethan Winer and bgape. They'll have to give you rundown on their product offerings, perhaps by PM. Downside to covering a sheet/section of raw fiberglass is lack of rigidity. Check the link in my sig for a completely DIY solution.


----------



## yngdiego




> Quote:
> Originally Posted by *rick11* /forum/post/12777506
> 
> 
> Can anyone give me some of the best websites to buy acoustic panels. Looking for panels with no fabric (will cover my own) and roughly 2 or 3 by 4 or 5 ft. Am in the Chicago area
> 
> 
> thanks!



Why not just buy "raw" insulation if you are going to cover it yourself? Most acoustic panels are simply insulation with a fabric covering. Some may add some edge treatments and enhancements, but basically that is what you are getting.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/12778189
> 
> 
> Why not just buy "raw" insulation if you are going to cover it yourself? Most acoustic panels are simply insulation with a fabric covering. Some may add some edge treatments and enhancements, but basically that is what you are getting.



That is "basically" what you are getting, but purchased "panels" usually have some easy way to mount.


----------



## rick11

Thanks guys - allow me to elaborate. My wife is very particular about design esthetics but she is willing to accept my perspective that the room has to sound good (as long as it still looks good). We could debate whether I should stay married or not but it has worked out for almost 28yrs so I'm willing to compromise and find a way to make it work. So, I have 2 areas of the room (1st reflection point) where we will hang floor to ceiling curtains. I want to put acoustic sound absorbing panels behind the curtains. I am not much of a do it yourselfer -too busy with my day job - so I just want to buy panels I can mount behind the curtains. THey need to be rigid since I may need to remove them at times (the curtains hide windows and although I will place the panels so the windows are covered, my wife wants to be able to open/access the windows from time to time). So a rigid panel would work best - i would just velcro the panel corners to the wall. Can i just buy rigid styrofoam insulation or something else from a HOme Depot - or do i need to buy a special acoustic panel. At the second reflection points on the wall, there will be picture frame molding that the panel would fit into. So the panel should be about 1in thick. My wife wants the panel color to match the paint color - so she has ordered samples, will then pick the fabric and finally match the wall paint to the fabric color (did i mention I am happily married). So again I want to buy some type of rigid sound absorbing panel that can be covered and then mounted.


I appreciate your help - and pls don;t laugh too loud!


rick


----------



## VA HDman

Hopefully your wife is looking at GOM fabric or something similar to cover the panel -- different fabrics will have different accoustical properties. It sounds like what you need is some Owens Corning 703 1" insulation. It comes in sheets that are 2'x4'. I just bought a box (180 sg. ft) for $40 at a local insulation shop. You might find someone locally that will sell it by individual sheets (HD and Lowes don't carry it). It's fairly rigid insulation, however you may still want to build a thin wood or metal frame to make the edges hard if you think people might push on the edge of the panel. HD sells 1x1 metal edging (it looks like 24 ga) in their sheetrock section which you can easily use to make a frame. Use some heavy duty 3M spray adhesive to attach the frabic to the framed panel. Then use 1" industrial velco (much stronger than normal velco) to attach the frame to the wall. If this is too much, PM bpape. He sells the GOM fabric, OC 703 insulation and completed panels -- he can also advise you regarding the accoustical properties of the different GOM fabrics.


Good Luck


28 years is a long time! I've been married 20 years, just not to same woman. You are smart to compromise -- if she leaves, she'll get half of the toys. Trust me, I know this from experience.


----------



## BasementBob

rick11



> Quote:
> Can i just buy rigid styrofoam insulation or something else from a HOme Depot - or do i need to buy a special acoustic panel.



Styrofoam is a reflector of sound, not an absorber.

Any of the materials on this page are good absorbers: http://www.bobgolds.com/AbsorptionCoefficients.htm 

Notice how as they get thicker (e.g. 4") they tend to absorb lower frequencies.

Lots of other things absorb too, but mostly high frequencies: http://www.bobgolds.com/Sabin.txt 



> Quote:
> At the second reflection points on the wall, there will be picture frame molding that the panel would fit into. So the panel should be about 1in thick.



I don't know of anyone selling fiberglass panels that thin, but certainly there are foam panels that thin.

http://www.realtraps.com (ethan)
http://www.readytraps.com (scott)
http://www.gikacoustics.com (bpape)
http://www.auralex.com (pretty and thin stuff)

(not a complete list)


The biggest chunk of fiberglass behind a curtain I'd ever seen is









from: http://www.royaldevice.com/custom.htm (the big floor Horn Subwoofer room with the polys everywhere)



GoM is http://www.guilfordofmaine.com 

Thier 701 series of fabrics (many colours) are mostly acoustically transparent, and fire resistant.


----------



## rick11

Basement Bob - thanks for the links - this will really help me, WIll check them out tonite and over the weekend.


VA HDman - thanks and yes she has GOM samples on order. and thanks for the marriage advice - i guess my 7.1 would become 3 or 4.1 if I left .....


Since u folks are so helpful, indulge me one more questions. Do any of the websites you showed me also offer to do an acoustical design i.e. what type of panels, where in the room, how many etc. Ideally send them the room layout and they would let you know what to do. I'd readily buy panels from someone who did this.


again many thanks


----------



## BasementBob

rick11:


> Quote:
> Do any of the websites you showed me also offer to do an acoustical design i.e. what type of panels, where in the room, how many etc.



All tend to recommend thier own products.

http://www.readytraps.com (scott)

does. I believe they do nice 3D drawings.

http://www.auralex.com (pretty and thin stuff)

does.
http://www.auralex.com/pcf/


----------



## Joel DuBay

Here's a *DIY Bass Trap tutoria*l I created based on the StudioTips Corner Absorber that utilizes readily available materials from local sources.


These "SCA's" have been around for many years and are easy to make.



Also check out the *Bass Traps Network* for free acoustical devices plans and information. It is commercial free, and no sales pitches from vendors. If you have something to submit there, please do.



Cheers,



~ Joel

ReadyAcoustics.com

Come see us at CES with Scaena and Balanced Audio


----------



## Ethan Winer




> Quote:
> Originally Posted by *BasementBob* /forum/post/12782038
> 
> 
> Ethan does telephone support, but beyond that I don't know



Besides telephone support and advice, my associate Scott and I both do drawings when needed. I use Visio mostly, but sometimes I'll draw traps right onto a photograph etc. Whatever it takes to be sure a customer understands what we have in mind for their room.


--Ethan


----------



## myfipie

bob wrote:



> Quote:
> GoM is http://www.guilfordofmaine.com
> 
> Thier 701 series of fabrics (many colours) are mostly acoustically transparent, and fire resistant.



I most say that GOM fabric is one of nicest fabrics around. I am SO glad that Bryan (Bpape) talked me into using it for our own products. Hands down guys if you are building acoustics spend the extra few bucks on GOM..

















Glenn


----------



## rick11

Ethan - thanks. I emailed you my basement drawing - any advice is welcome


rick


----------



## nathan_h

I'm hanging my Stewart (fixed wall mount) screen tomorrow and it doing the fittings today I realized that I have space for 2 inches of insulation behind it.


1) Is it worth it? It's not an acoustically transparent screen... but maybe sound gets through a bit, and it would be good to absorb.


2) Being a Sunday my choices for purchase are limited. Anything at a Home Depot that is acceptable?


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/12794992
> 
> 
> I have space for 2 inches of insulation behind it ... Is it worth it?



Yes, I think so. Though four inches would be better. But even two inches will help, and the lower frequencies absorbed by two-inch fiberglass will pass right through the screen.


--Ethan


----------



## nathan_h

That's cool. The more trapping the better.


But the downside is that means I probably DON'T hang my screen today since industrial places which could sell me something like rigid fiberglass aren't open on a Sunday :-(


I do have some old 2 inch auralex foam that I was going to use on first reflection points.... maybe I'll dump a bunch of that behind the screen, and then use fiberglass on the first reflection points where that stuff was going to go... of course, 2 inch foam doesn't do as much (especially in low frequencies) as 2 inch fiberglass....


Decisions decisions!


----------



## BasementBob

Ethan:



> Quote:
> Yes, I think so. Though four inches would be better. But even two inches will help, and the lower frequencies absorbed by two-inch fiberglass will pass right through the screen.



What's he going to get at Home Depot, that's 2" thick, that won't make the screen bow? Nothing can touch the screen ever.


----------



## tleavit

Well, I just got my first 2 panels of 2" in and played around with it at my front speaker reflection points and man, it really does help in my room. I cant wait to add another good 8 panels (I'll buy 2 at a time over time). The first thing I noticed was that I was able to hear the surround speakers much better.


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/12834437
> 
> 
> Well, I just got my first 2 panels of 2" in and played around with it at my front speaker reflection points and man, it really does help in my room. I cant wait to add another good 8 panels (I'll buy 2 at a time over time). The first thing I noticed was that I was able to hear the surround speakers much better.



Which two points did you treat?


----------



## tleavit




> Quote:
> Originally Posted by *pepar* /forum/post/12834648
> 
> 
> Which two points did you treat?






















I dont have pics of the panel yet since its not mounted yet.


The 2 front speaker reflection points (side wall) at the point shown in my image here. The panels are 2' X 4' x 2". I laid them sideways (horizontal long). In the case of the window to the left, It’s the perfect height for me to place the panel in the window at the exact same spot as the panel right side of the room. You cant see the panel in the window since the window is covered with heavy black drapes. This worked out better then I thought it would (was worried about the window).


My plan is to get 4ish more 2" or 4" panels soon and place them behind my screen that you see there. Theres a good 6+ inches of space back there (want to put an LCD back there still).


----------



## Terry Montlick




> Quote:
> Originally Posted by *tleavit* /forum/post/12834437
> 
> 
> Well, I just got my first 2 panels of 2" in and played around with it at my front speaker reflection points and man, it really does help in my room. I cant wait to add another good 8 panels (I'll buy 2 at a time over time). The first thing I noticed was that I was able to hear the surround speakers much better.



The first absorption you place in the room will make the most difference! More will help, and you have to treat at least 1/3 the room surface to really get to the point of diminishing returns.


I have heard talk of the danger of "overdeadening" a home theater room, but I have yet to encounter such a room in all of my listening and measurements. You can certainly overdeaden a recording or performance space, and this sucks the life out of it. But this is extremely hard to do for a home theater, whose role is to pass on uncolored the acoustic environment of the surround sound.


Regards,

Terry


----------



## pepar

If there's a rear wall, do that and the ceiling next.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/12834814
> 
> 
> The first absorption you place in the room will make the most difference! More will help, and you have to treat at least 1/3 the room surface to really get to the point of diminishing returns.
> 
> 
> I have heard talk of the danger of "overdeadening" a home theater room, but I have yet to encounter such a room in all of my listening and measurements. You can certainly overdeaden a recording or performance space, and this sucks the life out of it. But this is extremely hard to do for a home theater, whose role is to pass on uncolored the acoustic environment of the surround sound.


 Here's a room that's been over-deadened.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/12778003
> 
> 
> Usually, once a vendor has made a "panel" they cover it as well. You can take a section of fiberglass and cover it. GIK, I believe, sells "pillowcases" that are used to cover the sections. Size I know about is 2'x4', but there may be others. Glenn (GIK) hangs here. There are (at least) two other vendors here as well - Ethan Winer and bgape. They'll have to give you rundown on their product offerings, perhaps by PM. Downside to covering a sheet/section of raw fiberglass is lack of rigidity. Check the link in my sig for a completely DIY solution.



Just to clarify we DO NOT sell any kind of pillow case for DYI. We do sell GOM by the yard if someone needs it. Also bpape works with me over at GIK.










Glenn


----------



## nathan_h




> Quote:
> Originally Posted by *BasementBob* /forum/post/12801327
> 
> 
> Ethan:
> 
> What's he going to get at Home Depot, that's 2" thick, that won't make the screen bow? Nothing can touch the screen ever.



So the way this screen mounts, there was probably 2.3" of space so I was able to put a box of these behind the screen before hanging it:











Since I had a box of 24 (I think) I picked up "used" (never opened) in a color that the wife didn't want visible on the walls.....


----------



## pepar

Frequencies that would be absorbed by foam probably won't get through the screen (they'll be reflected) and frequencies that do pass through won't be absorbed much. 2" of this stuff just doesn't reach low enough frequency-wise. Fiberglass would have produced some results.


----------



## nathan_h

The screen is pretty opaque. The wedges mean there is an air gap. But I can see where high freq won't get through much and low freq won't be impacted much.


I wonder whether I should unmount the screen....and remove the panels....though MAYBE the full mass (foam + screen + draps) builds up usefully when I close the drapes over the screen for music listening.


Of course, I've ALSO used industrial strength adhesive, so removing the panels would mean not only unmounting the screen but probably pulling off the paint & plaster -- and ruining the foam.... so maybe that makes my decision for me.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/12851223
> 
> 
> The screen is pretty opaque. The wedges mean there is an air gap. But I can see where high freq won't get through much and low freq won't be impacted much.
> 
> 
> I wonder whether I should unmount the screen....and remove the panels....though MAYBE the full mass (foam + screen + draps) builds up usefully when I close the drapes over the screen for music listening.
> 
> 
> Of course, I've ALSO used industrial strength adhesive, so removing the panels would mean not only unmounting the screen but probably pulling off the paint & plaster -- and ruining the foam.... so maybe that makes my decision for me.



If the screen just barely touched the tips of the foam triangles, instead of the non-reflected frequencies vibrating the screen and passing through, they'd be dampened.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/12849554
> 
> 
> Fiberglass would have produced some results.



Agreed, though one way to get more performance out of foam like that is to mount it backwards, with the pointy side toward the wall. If it's not too late that's a good option. But my guess is it's too late and the stuff is glued solid to the wall, yes?


--Ethan


----------



## nathan_h

Yes, alas, too late. And the pointed bit is just about 1/4 inch shy of touching the back of the screen.


I'm curious: How does putting the pointy side towards the wall improve the performance of the foam? I just assumed the wedge/points was mostly a design/visual thing and that full/thick foam would actually work better -- but that by cutting it that way, they can make twice as many panels from the same amount of foam and just call it "2inch" foam, though about half of the material is actually cut away.


----------



## eugovector




> Quote:
> Originally Posted by *nathan_h* /forum/post/12864900
> 
> 
> Yes, alas, too late. And the pointed bit is just about 1/4 inch shy of touching the back of the screen.
> 
> 
> I'm curious: How does putting the pointy side towards the wall improve the performance of the foam? I just assumed the wedge/points was mostly a design/visual thing and that full/thick foam would actually work better -- but that by cutting it that way, they can make twice as many panels from the same amount of foam and just call it "2inch" foam, though about half of the material is actually cut away.



Most acoustic absorption material absorbs more effectively, and to lower frequencies, with an air gap behind it. Mounting it pointy side in would give you that gap, in a way.


----------



## BasementBob

Aren't we talking about a membrane/diaphragmatic absorber here?


Below is a bunch of guesses.


The screen is about 2oz per square foot. (That's another guess)


So, using f = 170 / sqrt(m d) = 304hz

m = surface density of the panel in pounds per square foot (2oz/16 = .125pounds)

d = 2.5 "


Sticking insulation in there makes compression isothermal rather than adiabatic, multiplying the depth by about 1.4 for whatever percentage volume has changed (not placement, volume). I figure those wedges, plus a bit of clearance to the screen, mean that half the volume is foam. So the adjusted depth would be about 3"


using f = 170 / sqrt(m d) = 277hz


In addition to lowering the peak frequency the foam would also weaken the absorption and widen the absorbed frequencies. (take a bell curve and stand on it)


I'm ignoring other effects (my bad), such as the rear wall, etc...


----------



## nathan_h




> Quote:
> Originally Posted by *BasementBob* /forum/post/12868381
> 
> 
> Aren't we talking about a membrane/diaphragmatic absorber here?
> 
> 
> Below is a bunch of guesses.
> 
> 
> The screen is about 2oz per square foot. (That's another guess)
> 
> 
> So, using f = 170 / sqrt(m d) = 304hz
> 
> m = surface density of the panel in pounds per square foot (2oz/16 = .125pounds)
> 
> d = 2.5 "
> 
> 
> Sticking insulation in there makes compression isothermal rather than adiabatic, multiplying the depth by about 1.4 for whatever percentage volume has changed (not placement, volume). I figure those wedges, plus a bit of clearance to the screen, mean that half the volume is foam. So the adjusted depth would be about 3"
> 
> 
> using f = 170 / sqrt(m d) = 277hz
> 
> 
> In addition to lowering the peak frequency the foam would also weaken the absorption and widen the absorbed frequencies. (take a bell curve and stand on it)
> 
> 
> I'm ignoring other effects (my bad), such as the rear wall, etc...



Which is to say the foam MAY be helping me, if I follow you right, but it wasn't the ideal placement for them...


----------



## BasementBob

nathan_h:


These are not meant to be what you have, just representative of the trends I was thinking of.


This is what I think the difference in absorption would be with those wedges not behind a screen, facing either way:










This is what I think having a screen/insulation would be like -- I'm not sure what the efficiency would be like, so there's two lines:










For helmholtz absorbers, I've read that putting the insulation near the front or the back, makes a difference.

But I don't know if I've read anywhere that it makes much of a difference for a membrane absorber (assuming nothing touches the membrane).


----------



## eugovector




> Quote:
> Originally Posted by *BasementBob* /forum/post/12871744
> 
> 
> 
> This is what I think having a screen/insulation would be like -- I'm not sure what the efficiency would be like, so there's two lines:



So by your estimation, his foam may be doing more harm than good, absorbing a very narrow frequency spectrum (bad, unless you know you have a room peak there), instead of absorbing evenly over a wide range of frequencies (usually, the prefered effect)?


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/12864900
> 
> 
> Yes, alas, too late. And the pointed bit is just about 1/4 inch shy of touching the back of the screen.



Can't you move your screen to hang a few inches farther away from the wall?



> Quote:
> How does putting the pointy side towards the wall improve the performance of the foam?



You are correct that removing foam material in a pattern looks nice and lets them get twice as many panels from the same piece of foam. But now there's only half as much absorbing material! By reversing it on the wall, the thicker portion of the foam slab will be an inch away from the wall, and that extends its absorption to lower frequencies. If you want a more detailed explanation, see the section _Optimizing the air gap_ in my Acoustics FAQ:

http://www.ethanwiner.com/acoustics.html 


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *BasementBob* /forum/post/12871744
> 
> 
> For helmholtz absorbers, I've read that putting the insulation near the front or the back, makes a difference.
> 
> But I don't know if I've read anywhere that it makes much of a difference for a membrane absorber (assuming nothing touches the membrane).



For maximum effectiveness, the porous insulation should be put near the front. This is where maximum air flow occurs, both for Helmholtz and membrane type absorbers.


Regards,

Terry


----------



## BasementBob

Terry:


Thanks.

I have a diagram somewhere that implies that, but I still haven't read a formula for that anywhere. (Figure 6.2 on page 158 of "Acoustic Absorbers and Diffusers. Theory, Design and Application" by Trevor J Cox and Peter D'Antonio.)
RPG's Modex seems to put the little bit of absorption in the middle -- at least according to the sales literature.


----------



## Terry Montlick




> Quote:
> Originally Posted by *BasementBob* /forum/post/12877194
> 
> RPG's Modex seems to put the little bit of absorption in the middle -- at least according to the sales literature.



Yeh, that's what it appears on their schematic representation. But having dissected a Modex Corner, I can state otherwise.







They build them with the absorption in the right place -- right behind, but not up against, the membrane.


Regards,

Terry


----------



## BasementBob




> Quote:
> Originally Posted by *eugovector* /forum/post/12873722
> 
> 
> So by your estimation, his foam may be doing more harm than good, absorbing a very narrow frequency spectrum (bad, unless you know you have a room peak there), instead of absorbing evenly over a wide range of frequencies (usually, the prefered effect)?



I'd go the other way -- putting the foam behind the screen was probably a good thing.


Having the screen 2.5" out from the wall is what makes it a membrane absorber. There are other membrane absorbers in the room, e.g. walls, leather couch.

Obviously I'm more worried about having an un-flat screen (obvious video problem) then having the screen be a membrane absorber (minor audio).


I don't know if you've ever used a kettle drum, but it has a foot peddle to adjust the tension of the drum skin, stepping on the peddle makes it tighter and the frequency of the drum goes up. The drum 'rings', there's an initial impulse when you tap it with the hammer, and the tone continues after the impulse/tap.


Membrane absorbers can also ring, and are damped by adding insulation to reduce that, but damping has other effects: lowers the height of the peak absorption, and widens the bandwidth of absorbed frequencies (while increasing the absorption at other frequencies), and lowers the frequency of the peak (not shown in below diagram, sorry). I sort of mentioned that earlier when I wrote "take a bell curve and stand on it".


In theory it's something like this:










Further reading:
Custom Audio Designs Membrane Absorbers 
Paul White at SoundOnSound talking about Resonant Absorbers 
BBC 1992/10 Design of Modular Sound Absorber for Very Low Frequencies 
BBC 1992/11 Modular Wideband Sound Absorber


----------



## nathan_h

Most interesting. Here's another tid bit. I bought most of the foam "used" for about $0.60 to $0.70 on the dollar, from a fellow on audiogon that bought it but never used it, so I'm discovering what exactly I have as I open each box. Turns out I have a second set of the wedges I put behind the screen. I could add those, inverted (mated) with what is already there, and it actually WOULD then touch the screen (in fact, maybe a little too much, I'd need to test).


It sounds like that would be a useful thing, but here are two caveats:


1) The screen is not easy to unmount & is perfectly aligned right now.

2) I could use this second set of wedges at the first reflection points on the ceiling, which are otherwise bare at this point.


Given those factors, I'm inclined to use this box of foam on the ceiling's first reflection points.


------------


File in the "what I'd do differently next time":


I bought the four boxes of Auralex foam, and six Real Traps, on the used market over the past year, and paid far less than retail.


BUT if I had just started out buying ONLY Real Traps, and got ones that work for high frequency absorption, too, the price NEW would have been only slightly more than buying "used" bass traps and separately "used" foam.


----------



## ginosony

Hi, this thread is very helpful, but man 97 pages it's a lot of stuff to read. I began my room treatment last week, i completely treated my front wall, i've found my first reflection on the side walls and ceiling for 3 front speakers, i treated my ceiling. Now for the side walls i want to treat the bottom of the wall, i have 7 feets under soffit, if i put 30 inches on the bottom, and up to 6 feet where the first reflections are, is that enough cause i wonder if i put 48 inches if my room will sound dead??? I will split the panels every 48 inches with a 2 x 1 piece of wood, it will help for the GOM.


----------



## bpape

No way to know without knowing a lot of other things like:


30" of what? 1"? 2"?


How many seats in the room?


How many people?


Are you doing any 2 channel listening in there?


You're likely better off posting your own thread with some additional details to get more specific answers.


Bryan


----------



## ginosony




> Quote:
> Originally Posted by *bpape* /forum/post/12889673
> 
> 
> No way to know without knowing a lot of other things like:
> 
> 
> 30" of what? 1"? 2"?
> 
> 
> How many seats in the room?
> 
> 
> How many people?
> 
> 
> Are you doing any 2 channel listening in there?
> 
> 
> You're likely better off posting your own thread with some additional details to get more specific answers.
> 
> 
> Bryan



30" of 1"

5 seats, 3 front and 2 on riser

no 2 channel listening

usually 1 to 3 persons

i heard u better treat the room for multi channels or for 2 channels, not try to do both.


my room is 11.5' x 21' x 7.5', front wall completely treated, i found first reflexions on side walls, ceiling first reflexions treated

no bass trap since i have only 15 inches each side of my 110" screen


----------



## Joel DuBay




> Quote:
> Originally Posted by *bpape* /forum/post/12889673
> 
> 
> No way to know without knowing a lot of other things like:
> 
> 
> 30" of what? 1"? 2"?
> 
> 
> How many seats in the room?
> 
> 
> How many people?
> 
> 
> Are you doing any 2 channel listening in there?
> 
> 
> You're likely better off posting your own thread with some additional details to get more specific answers.
> 
> 
> Bryan






Bryan is asking the right questions here. Heed his inquiry.




Joel DuBay

basstraps.net


----------



## bpape

Have you done any broadband bass absorption in the room? How did/do you plan to treat the front wall?


Bryan


----------



## Sands_at_Pier147

There's probably 100 places to post this question, but since the question about "one inch or two" just came up here, I figure I'll ask it here ...


With regards to a blanket-type insulation (linacoustic or OC SelectSound), do two layers of 1" insulation equal one layer of 2" insulation? Or is there a boundary effect between the two layers that would prevent it from performing as if it were one homogenous single layer?


----------



## bpape

They should act the same. It's just not real fun trying to get 2 layers of Linacoustic to stay up right. It's much easier to use 2" of 703 or cotton where needed.


Also, remember that there are density differences for any areas where you may be bonding a facing to get a membrane effect.


Bryan


----------



## Sax

I'm looking to get some Owens Cornings 703, 48x24x2. Will it hurt to put it in a wood frame around the outside of the 703. I want it to hold it's shape and to help with hanging on the wall.


----------



## eugovector




> Quote:
> Originally Posted by *Sax* /forum/post/12906777
> 
> 
> I'm looking to get some Owens Cornings 703, 48x24x2. Will it hurt to put it in a wood frame around the outside of the 703. I want it to hold it's shape and to help with hanging on the wall.



That's what I did. It can be tough to find straight wood planks, though. I went with pine 1x3s.


----------



## pepar

 DIY project


----------



## nathan_h

Have put up temporary treatments in my room, but am of course, waiting to secure some of them until the seating situation is worked out.


Here is some interesting data.


First, the room has very few modes? If I am reading the Bob Gold results right.


Second, according the tool on UltimateAVMag.com, I could have one row of seats essentially against the back wall, and so long as no one sits midway between the side walls, there are few problems there. (In fact, it almost looks more smooth than sitting at 1/3 the room length from the back wall, which is where the first row would be.)


Am I reading this stuff right?

 

www.bobgolds.com Mode RoomModes2.pdf 71.20703125k . file

 

frequency-response-1.pdf 14.2353515625k . file


----------



## jjackknife




> Quote:
> Originally Posted by *pepar* /forum/post/12908164
> 
> DIY project



Pepar... what kind of "adhesive" did you use for those?


----------



## bpape

If you want to do frames and find some straight wood - go to Home Depot and go back in with the Oak and nice clear Pine. They have Poplar craft wood back there in 1/2" thickness that is 1, 1.5, 2, 2.5, 3, 4, and 6" wide and comes in 1', 2', and 4' lengths. It's hard and straight and easy to work with. It's a bit more than pine but not much.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *jjackknife* /forum/post/12913134
> 
> 
> Pepar... what kind of "adhesive" did you use for those?



I used a contact adhesive. I applied it to both surfaces - two coats on the mondo-porous fiberglass, let it dry until just barely tacky and then pressed the 'glass in place.


I thought it was necessary to not only have a frame, but a back as well. Aside from the routing and mitering of the frame members I had a woodworking friend do, it was a DIY project. The frame is poplar and the backer is 1/4" luan plywood.


----------



## jjackknife




> Quote:
> Originally Posted by *pepar* /forum/post/12916472
> 
> 
> I used a contact adhesive....



most "contact cement" are specifically for wood to wood contact. I wonder if your ceiling framed one will droop over time!?! how long has it been hanging? I'm considering trying your method with a large frame (8 ft sq?)


----------



## pepar




> Quote:
> Originally Posted by *jjackknife* /forum/post/12918952
> 
> 
> most "contact cement" are specifically for wood to wood contact. I wonder if your ceiling framed one will droop over time!?! how long has it been hanging? I'm considering trying your method with a large frame (8 ft sq?)



I don't recall if the adhesive was for bonding specific materials, but I can tell you that it held my thumb and forefinger together pretty well.










Seriously though, I believe it said "general purpose" and had a long list of materials that could be stuck together. And that is also why I slathered TWO coats of it onto the _fabric covered side_ of Owens Corning SelectSound Black . The front ceiling absorber has been in place since 6/1/05 and shows no evidence of sagging.


After 2-1/2 years, if I had it to do over again, I'd probably place diffusion there and cover it with the same black GOM (for light reflectivity reasons). My speakers - and any I'm likely to have in there - have tightly controlled vertical dispersion, so I'm probably not getting much "first reflection" from that point. I feel like I've over-dampened my room and diffusion there would address both possible acoustical reflection AND put some air back into the room.


----------



## eugovector

What's diffurion? Are you saying that light is going through the GOM, bouncing off the fiberglass, and bouncing out?


----------



## jjackknife




> Quote:
> Originally Posted by *pepar* /forum/post/12919278
> 
> 
> ... My speakers - and any I'm likely to have in there - have tightly controlled vertical dispersion, so I'm probably not getting much "first reflection" from that point...



hmm... i have Klipsch spkrs.... very directional tweets. i may begin with nothing there (9' ceiling) and see what happens. I will start my construction thread and get some more thoughts on that.


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/12919332
> 
> 
> What's diffurion? Are you saying that light is going through the GOM, bouncing off the fiberglass, and bouncing out?



No, I'm saying that I'm thinking of trying diffusion on the front ceiling area instead of the 4'x8' absorber that's there now. And I'd cover it with GOM.


----------



## pepar




> Quote:
> Originally Posted by *jjackknife* /forum/post/12924480
> 
> 
> hmm... i have Klipsch spkrs.... very directional tweets. i may begin with nothing there (9' ceiling) and see what happens. I will start my construction thread and get some more thoughts on that.



Pls link it here. Or PM me with it.


----------



## jjackknife

started my construction thread... may take a couple days to get updated to the present...

http://www.avsforum.com/avs-vb/showthread.php?t=983731


----------



## eugovector




> Quote:
> Originally Posted by *pepar* /forum/post/12924876
> 
> 
> No, I'm saying that I'm thinking of trying diffusion on the front ceiling area instead of the 4'x8' absorber that's there now. And I'd cover it with GOM.



Got it. I thought there was some great acoustic material that I was missing and the sucker reflected light like mad. A google search didn't turn up anything, so I had to ask.


----------



## CAK

Dedicated 2 channel room 14x12x8. Whats the word on front wall treatment?


I have a 3x5 bay window in the middle of the front wall (in-between speakers). I have 2x4x2" panels on either side of the window, 2" blinds with thin drapes over window. Thinking about adding an additional acoustic panel over window, or possibly an acoustic blanket over window.


That would be a total of (2) 2x4x2" panels and either an additional panel 3x5' or blanket 3x5' covering the 3x5' window. Does this sound like overtreatment for a 12' long wall or am I close?


For reference, I have (2) 2x4x2" panels on either side wall (14' wall) covering 1st and 2nd reflections with (2) more panels on the back wall, 3 feet behind listening chair.


Any suggestions would be appreciated.


----------



## Mit07

Hi guys,


I have a basement HT and music listening room that could benefit from some sound treatment. The space is approxiimately 13 x 30, however it does open to other sections of the basement.


I would like to get the names of some experts in the Boston, MA area that would be willing to examine the room / make recommendations / sell products / and install.


Please PM me.


Thanks for your help.


----------



## eugovector

Well, I'm no expert but I'll give you my two cents if you'd like










I'll be in the Boston area from March 6th - 11th.


----------



## Mit07

I appreciate the offer however, I was looking for a acoustic tech/dealer/installer type.


PS...I use to ski at Pleasant Valley when I was a kid. Great little town.


----------



## eugovector

I just moved here a year and a half a go. They must have built a gas station where your skiing hill used to be, or maybe I just haven't found it yet. God luck with the project, post pictures when you're done.


Marshall


----------



## cpc

I need some advice for a front projector home theatre room with bright sound. My receiver and speakers are bright and forward sounding in the room. Some CD's sound great, while others sound too bright and harsh. Apparently the receiver I have is revealing and my speakers are a little bright. Marantz SR9600 and PSB Image T65. I have a 11' 8" x 17' long room with a 7' 4" ceiling. Two side walls and ceiling are drywall. Floor is carpet and back wall is concrete. I am thinking of painting first and then adding some acoustic treatment.


Any idea's on acoustic panels and/or material that I can use to both soften the sound and keep light reflections low?


----------



## nathan_h




> Quote:
> Originally Posted by *nathan_h* /forum/post/12909713
> 
> 
> Have put up temporary treatments in my room, but am of course, waiting to secure some of them until the seating situation is worked out.
> 
> 
> Here is some interesting data.
> 
> 
> First, the room has very few modes? If I am reading the Bob Gold results right.
> 
> 
> Second, according the tool on UltimateAVMag.com, I could have one row of seats essentially against the back wall, and so long as no one sits midway between the side walls, there are few problems there. (In fact, it almost looks more smooth than sitting at 1/3 the room length from the back wall, which is where the first row would be.)
> 
> 
> Am I reading this stuff right?



Hmmmm. So I did some listening tests by sitting in locations that these tools would indicate are good and bad, and it appears the tools are accurate.


For example, unlike almost every other room I've been in, sitting back against the back wall does NOT create boomy bass. That's REALLY weird. Guess I should not have questioned the science behind the equations, it just flies in the face of most rule of thumb statements and my personal experience.


----------



## btg001

I am early in the design phase of a HT, and very much at the beginning of understanding acoustics, even after reading through 98 pages of posts. To make sure I at least have the basics correct, I'm hoping the folks here can confirm my understanding.


From what I've read, it seems there are two basics categories of acoustics... isolation and absorption / diffusion. It appears to me that design / build (framing and rocking) is where most isolation is done. Absorption / diffusion seems to be typically done after the room is built and you can listen to the sound produced and precisely determine first reflection points, etc.


Isolation won't be much of a concern for me (not to start a firestorm) as my HT is basically housed in a concrete bunker... floor and 2 1/2 walls are poured concrete, and the ceiling is corrugated steel and poured concrete under the garage floor. Remaining walls are doubled but separated 2x6 framing for serious load-bearing purposes (basically 2 freestanding 2x6 walls backed up to each other). HVAC will be baffled, and doors will be treated.


Since I'm early in the design stage, what I'm looking for is advice on whether there are absorption / diffusion treatments that I can build into the room design before starting construction. For example, since the room is 32 x 22 x 8 - 8.5, I'll have nice, long walls to create some serious echo. So I'm thinking about lateral (22 ft) boxed beams along the ceiling, since the steel and concrete is held up by 12" I-beams spaced every 6 feet, with the spaces between the ceiling being rocked and recessed 6" above the bottom of the beams. Breaking up the ceiling should help with diffusion, correct?


Similarly, I'm thinking about building columns that come out from the walls 4" - 6" meeting up the ceiling beams, which again should help with diffusion. The initial thoughts are decorative fiberglass or polyurethane raised panel columns... the paneling introduces more angles to the surface. And there will be soffits down the long walls for HVAC. My basic understanding is that this works like stealth aircraft... breaks in smooth surfaces scatters the signal, cutting down echo. I realize this still leaves a number of 6' x 8' flat walls, but I'm hoping every little bit helps.


Building absorbing panels into the wall instead of sheetrock isn't an option, building code requires all walls to be rocked. But are there other treatments I should be thinking about before the paint goes on the walls?


In summary, since I have an opportunity to design treatments in from the start rather than retrofitting, are there other items I should be considering?


Any help is greatly appreciated. Thanks.


- Steve.


----------



## Terry Montlick




> Quote:
> Originally Posted by *btg001* /forum/post/12948016
> 
> 
> ...
> 
> Building absorbing panels into the wall instead of sheetrock isn't an option, building code requires all walls to be rocked.



Steve,


Absorption, either in the form of discrete panels of continous fabric-hidden sheets, goes *over* the sheetrock, not instead of it. It is always an option according to building code, even for the strictest commercial construction. You just have to assure that the materials have the correct fire/flamespread ratings.


Regards,

Terry


----------



## pepar

I've cut enough sheets of 703 to yield the triangles for the first front vertical corner. From handling them I'm wondering if settling (over time) will decrease the effectiveness of the trap? If so, should I install some sort of support to divide the stack into several groups reducing the weight on the bottom wedges? TIA!


----------



## yngdiego

I asked the same questions a few months ago, and the consensus was NO. So I have several 8' high stacks covered in GOM with no support.


----------



## jjackknife




> Quote:
> Originally Posted by *pepar* /forum/post/13019036
> 
> 
> I've cut enough sheets of 703 to yield the triangles for the first front vertical corner. From handling them I'm wondering if settling (over time) will decrease the effectiveness of the trap? If so, should I install some sort of support to divide the stack into several groups reducing the weight on the bottom wedges? TIA!



I suggest you don't leave it free at the top. Add some sort of weight or pressure on top to compress the stack to begin with. In other words, stack to 8'... then push the stack down & add one more piece.


----------



## yngdiego




> Quote:
> Originally Posted by *jjackknife* /forum/post/13022144
> 
> 
> I suggest you don't leave it free at the top. Add some sort of weight or pressure on top to compress the stack to begin with. In other words, stack to 8'... then push the stack down & add one more piece.



I ended up getting 49 triangles in my corner with about 1/2" gap at the top. If you compress them too much, they will want to bulge out and depending on how you have them held in, might burst out into the room.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/13022209
> 
> 
> I ended up getting 49 triangles in my corner with about 1/2" gap at the top. If you compress them too much, they will want to bulge out and depending on how you have them held in, might burst out into the room.



Well, plus if you compress 703 too much, you will no longer have 703. As it is said to be the ideal density for bass traps, turning it into "704" may not be a good idea.


----------



## BasementBob

702 is the best for superchunk corner traps. You won't find 702 anywhere though.

But I think we're picking nits.(Nitpicking - the practice of meticulously searching for minor, even trivial errors)


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/13028869
> 
> 
> 702 is the best for superchunk corner traps. You won't find 702 anywhere though.
> 
> But I think we're picking nits.(Nitpicking - the practice of meticulously searching for minor, even trivial errors)



So, the bottom of my 703 stack even if compressed to 703.5 will perform essentially the same? Cool!


----------



## jjackknife

My gosh guys... This aint rocket science! bend a little... you won't break it!


----------



## Terry Montlick




> Quote:
> Originally Posted by *jjackknife* /forum/post/13029649
> 
> 
> My gosh guys... This aint rocket science!



Yes. Rocket science is easier.









If you compress 703 to half its original volume (twice the density), its acoustic resistivity increases by only 28 percent. This parameter is what largely determines fiberglass absorption, and that increase is not very large.


Regards,

Terry


----------



## nathan_h

Dropped a note to GIK folks yesterday but perhaps someone here knows: The GIK 244 panel and the GIK242 panel..... do they have the same broadband absorption but with the 244 going LOWER? That is, can I use the 244 at first reflection points? Or is it one of those bass traps that actually deflect higher frequencies (to avoid making the room too dead)?


----------



## pepar

I used eye screws in the floor and ceiling and stretched steel wire between them to hold my SSC bass trap in the corner.


Stacking in a corner is easy, especially one that will be hidden behind a false wall. Placing one at the corner formed by a wall and the ceiling will not be so simple. I've thought of going to a local metal shop and having some thin sheet metal bent into a 45° angle to hold the wedges in place at their two 45° corners. If the bracket is 2" x 2" with one 2" side mounted to the wall (or ceiling) and the other 2" side wrapping around the face (hypotenuse) of the wedge, will there be any reduction in effectiveness of the trap by covering 2" in from each wedge corner, i.e. 20" of each 24" face would be "open."


----------



## eugovector




> Quote:
> Originally Posted by *pepar* /forum/post/13053678
> 
> 
> I used eye screws in the floor and ceiling and stretched steel wire between them to hold my SSC bass trap in the corner.



Great idea, thanks pepar. Do post picture on your website of your progress with the AT screen. My long term plans always included FProj, but have only started to examine AT (though I think I would really like it). Curious to see how yours goes.


----------



## pepar

Yes, I am snapping pics of everything as I go.


Hopefully, I can get some expert comment on this part of my post! TIA!!!


> Quote:
> Originally Posted by *pepar* /forum/post/13053678
> 
> 
> Stacking in a corner is easy, especially one that will be hidden behind a false wall. Placing one at the corner formed by a wall and the ceiling will not be so simple. I've thought of going to a local metal shop and having some thin sheet metal bent into a 45° angle to hold the wedges in place at their two 45° corners. If the bracket is 2" x 2" with one 2" side mounted to the wall (or ceiling) and the other 2" side wrapping around the face (hypotenuse) of the wedge, will there be any reduction in effectiveness of the trap by covering 2" in from each wedge corner, i.e. 20" of each 24" face would be "open."


----------



## MTBDOC

I'm about ready to make my corner 'chunks' as well, and am trying to figure out the same thing...how to keep everything in place. Mine will be in the back corners of a room, 10' high, using rock wool. This is a finished, carpeted room. Crown molding and baseboards too.


Suggestions?


----------



## pepar




> Quote:
> Originally Posted by *MTBDOC* /forum/post/13062041
> 
> 
> I'm about ready to make my corner 'chunks' as well, and am trying to figure out the same thing...how to keep everything in place. Mine will be in the back corners of a room, 10' high, using rock wool. This is a finished, carpeted room. Crown molding and baseboards too.
> 
> 
> Suggestions?



Been to the Studiotips Forum " Treatment " section? It's _all_ interesting and informative, but click on Studiotips SuperChunk (what we're both building) and then the link - http://www.bobgolds.com/TrapHarder/home.htm . From the forum you can follow other links and you can also google to find others who've traveled this way before.


In addition to the SSCs behind my false wall, I will be installing some in the theater itself. For those, I'd like a higher "level" of finish than on the one pictured at the Bob Gold's link. The trim in my theater is American Chestnut, so I will be designing a trim/molding that can be milled from that wood that will hold both the wedges in place and the GOM covering as well. Haven't turned my attention to that design yet.


edit: For rockwool, note the suggestion that "use rockwool at least in the 4 to 5 lbs range" . . .


----------



## yngdiego




> Quote:
> Originally Posted by *MTBDOC* /forum/post/13062041
> 
> 
> I'm about ready to make my corner 'chunks' as well, and am trying to figure out the same thing...how to keep everything in place. Mine will be in the back corners of a room, 10' high, using rock wool. This is a finished, carpeted room. Crown molding and baseboards too.
> 
> 
> Suggestions?



For my OC703 super chunks, I used 1/2" L shaped plastic molding that ran floor to ceiling. I pushed it up against the left and right edges of the stack so that it trapped it against the wall. I then nailed it to the wall every 2', stretched GOM across it using industrial strength GOM, and covered L/R outside edges with quarter round wood molding I painted to match the wall color.


IMHO, it looks great, was easy to do and did the trick.


----------



## nathan_h




> Quote:
> Originally Posted by *nathan_h* /forum/post/13039752
> 
> 
> Dropped a note to GIK folks yesterday but perhaps someone here knows: The GIK 244 panel and the GIK242 panel..... do they have the same broadband absorption but with the 244 going LOWER? That is, can I use the 244 at first reflection points? Or is it one of those bass traps that actually deflect higher frequencies (to avoid making the room too dead)?



Still waiting to hear from GIK. Left another msg on their phone line Thursday. After reading through their site more, although they don't publish the measurements of the 242 panels, they IMPLY that the 242 and 244 are the same UNTIL you get to the lower frequencies, implying I could use the 244 for first reflection points. Guess I'll try again by phone Monday.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/13063441
> 
> 
> Still waiting to hear from GIK. Left another msg on their phone line Thursday. After reading through their site more, although they don't publish the measurements of the 242 panels, they IMPLY that the 242 and 244 are the same UNTIL you get to the lower frequencies, implying I could use the 244 for first reflection points. Guess I'll try again by phone Monday.



I think it's common to use broadband absorbers at first reflection points, but not necessarily ones that extend really deep. Bass is most easily trapped in corners, so that's where I'd place "chunks."


----------



## jjackknife




> Quote:
> Originally Posted by *yngdiego* /forum/post/13062427
> 
> 
> IMHO, it looks great, was easy to do and did the trick.



... & pics would be great, i'd like to see the "how to" & the completed


thanks.


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/13063681
> 
> 
> I think it's common to use broadband absorbers at first reflection points, but not necessarily ones that extend really deep. Bass is most easily trapped in corners, so that's where I'd place "chunks."



Well, in this case I've got 6 Real Traps in the corners, but I am using Auralex at the first reflection points -- which is okay, but can be improved upon (both in terms of WAF [she hates foam] and absorption [fiberglass]).


But if I'm going to hang a "2 inch" panel on the wall, I might as well hang a "4 inch" panel, if it makes it even more broadband, but doesn't sacrifice anything over the "2 inch" panel. I put the measurements in quotes because the GIK panels appear to be 1 or 2 inches bigger than the thickness of the acoustic material.


I'll be buying either their 2inch panels or 4 inch panels (preferably) once I hear from them, methinks.


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/13065235
> 
> 
> Well, in this case I've got 6 Real Traps in the corners, but I am using Auralex at the first reflection points



Auralex foam is okay for reflections if it's at least two inches thick. But it's a mistake to assume that all commercial absorber panels are acceptable for that use. For example, RealTraps offers most panels in both standard and HF styles for either bass trapping or reflections. Using one of our standard panels at a reflection point would be a mistake.


--Ethan


----------



## MTBDOC




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13069098
> 
> 
> Auralex foam is okay for reflections if it's at least two inches thick. But it's a mistake to assume that all commercial absorber panels are acceptable for that use. For example, RealTraps offers most panels in both standard and HF styles for either bass trapping or reflections. *Using one of our standard panels at a reflection point would be a mistake.*
> 
> --Ethan



Why? Am I missing something here? Obviously the higher frequency is the primary component as far as imaging, but what difficulty is created by more broad-band absorption?


----------



## nathan_h




> Quote:
> Originally Posted by *MTBDOC* /forum/post/13069193
> 
> 
> Why? Am I missing something here? Obviously the higher frequency is the primary component as far as imaging, but what difficulty is created by more broad-band absorption?



The traditional Real Traps are designed to REFLECT rather than ABSORB high frequencies. This is because you continue to reap benefits from adding bass trapping to a room, almost ad infinitum -- but after a point absorbing high frequencies can hurt a room. So one places the traditional Real Trap in a corner, where you don't need (and probably don't want) high frequency absorption.


(I think Ethan makes a modified version for use as a true broad band absorber.


----------



## nathan_h




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13069098
> 
> 
> Auralex foam is okay for reflections if it's at least two inches thick. But it's a mistake to assume that all commercial absorber panels are acceptable for that use. For example, RealTraps offers most panels in both standard and HF styles for either bass trapping or reflections. Using one of our standard panels at a reflection point would be a mistake.



Yes, I haven't been too disappointed with the Auralex foam (which is their 2 inch thick panels) at the first reflection points BUT the wife hates the way they look. I was able to get "sign off" on the look of the GIKs so that is what will go on the walls. But I am wanting to make sure that the GIK 4 inch panels are NOT designed to reflect high frequencies the way the traditional Real Trap (for example) panels are designed, otherwise I should use the 2 inch GIK panels.


I'm loving the Real Traps in the corners, though because of the way the roof is conscructed, the ceiling/wall intersections are not usable. So I've got two 2x4ft Minitraps straddling the rear corners/walls, and then two 2x4 and two 2x2 Minitraps straddling the floor/wall juncture at the front of the room -- though with the ones in front I may not get to keep them at a 45 degree angle and have to place them vertical, about 2 inches off the wall.... though I have to ALSO place some 2 inch auralex on them to help deaden high frequency reflections off the front wall. (The front speakers are studio monitors on 16 inch stands.)


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/13069680
> 
> 
> The traditional Real Traps are designed to REFLECT rather than ABSORB high frequencies ... (I think Ethan makes a modified version for use as a true broad band absorber.



Exactly. We offer both types depending on what's needed at each location.


--Ethan


----------



## pepar

Some 1x2's and 1/4x3's and the wall/ceiling superchunk is underway. This design is simple and cheap, though I'll need to come up with something more "finished" for the traps in the room and not behind the false wall. Next I'll install one of these on the ceiling and then "load" the chunks.


----------



## saprano

hi i just finished setiting up my ht and would like to get some pannels, i would like to know what kind do i need, how many and what size? the pannels will be going into a small bedroom.


----------



## pepar

OK, here is the above mounting system in action:


----------



## eugovector




> Quote:
> Originally Posted by *pepar* /forum/post/13094545
> 
> 
> OK, here is the above mounting system in action:



Very nice, I'll be curious to see the final product. What's the plan, fabric soffit?


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/13095353
> 
> 
> Very nice, I'll be curious to see the final product. What's the plan, fabric soffit?



No complete plan yet for the traps that will be seen. I don't like retro'ing soffits into smaller rooms; they're too encroaching. And the squared point seems "unfriendly."










The idea that I'm leaning toward is going to a local metal fabricating shop and having them bend some light sheet metal strips at a 45° angle. This takes the scheme I've used so far of holding the chunks in place by their corners, but eliminates the "external" fastening. A 5" wide strip bent with a 3" base and a 2" hypotenuse will allow for easy fastening to the wall or ceiling. I'm less clear on how to cover it, but molding could be screwed to the bracket and hold GOM in place.


Off to cut more wedges . . .


----------



## TheTurk

I have a long-narrow room I am in the process of setting up the room. I was hoping to put base traps on the two front corners but I only have 18 inches of space between my screen and the side walls. This is basically where my Left and Right speakers were going on stands. Would it make any difference in sound if I cut the Roxul 60 in the shape of 18" - 10" triangles and stick them in the front corners from the floor to the ceiling?


----------



## bpape

Standard chunk style absorbers are 17x17x24" - a 2'x4' piece yeilding 8 triangles that size so that would fit.


Nathan


I sent you a PM. If we've missed something, I apologize. We try to return all calls the same day. PM me with your phone number and I'll be happy to work with you to figure out your needs.


Bryan


----------



## pepar

And one 2x4 sheet of OC 703 yields 16 lineal inches of trap. A SSC-style trap between the floor and an 8' ceiling will use six sheets.


----------



## Dan Woodruff

How does OC 703 and JM Linacoustic RC differ when used in corner traps like these?


----------



## price3

Wow pepar, how many bundles of 703 did you buy?


----------



## BasementBob

pepar


Have you considered a cube of 703 in the corner?









from: http://www.auralex.com/bass_traps_at...aps_atom12.asp


----------



## eugovector




> Quote:
> Originally Posted by *BasementBob* /forum/post/13100153
> 
> 
> pepar
> 
> 
> Have you considered a cube of 703 in the corner?
> 
> [/url]



I'm not a fan of that look, but different strokes for Different Folks. Probably works great though.


----------



## pepar




> Quote:
> Originally Posted by *price3* /forum/post/13100010
> 
> 
> Wow pepar, how many bundles of 703 did you buy?










Three bales consisting of twelve 2x4 sheets in each. And, believe me, my wife is ecstatic to see them disappearing from the basement.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13099960
> 
> 
> How does OC 703 and JM Linacoustic RC differ when used in corner traps like these?



I would think they would perform the same if the Linacoustic is the same density.


----------



## pepar




> Quote:
> Originally Posted by *BasementBob* /forum/post/13100153
> 
> 
> pepar
> 
> 
> Have you considered a cube of 703 in the corner?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> from: http://www.auralex.com/bass_traps_at...aps_atom12.asp



If I do up a corner and continue across the ceiling/wall corner, I would "miter" them for a continuous appearance. Is there something gained, performance-wise, by placing a cube in the corner, or is that just an aesthetic design element?


edit: I'll bet the cube was their way of avoiding mitering . .


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/13101739
> 
> 
> I would think they would perform the same if the Linacoustic is the same density.



Sorry, I should have been more specific. Does anyone know the coefficients of OC 703 that you are using and JM Linacoustic RC 1in? If so, can you post them for me or send me a PM?


Thanks,

Dan


----------



## two-rocks




Dan Woodruff said:


> Sorry, I should have been more specific. Does anyone know the coefficients of OC 703 that you are using and JM Linacoustic RC 1in? If so, can you post them for me or send me a PM?
> 
> 
> It's probably in this long thread somewhere...but I'll add it if not:
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> 
> Thank Bob Gold


----------



## Dan Woodruff

Thanks for the link, two-rocks.


Pepar,

Which OC 703 are you using?


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/0
> 
> 
> Pepar,
> 
> Which OC 703 are you using?



Dan, there's only one kind of 703. I am using it unfaced. Here's the submittal data sheet .


----------



## pepar

This will be my last post on this project as it marks the end of the "acoustical treatment" phase until I install additional bass traps in the theater and that is probably a month or two away.


All superchunk traps in front are complete and LCR speakers are mounted and laser-aligned. After wiring everything, I'll re-hang the 2" Linacoustic and mount the AT screen. I'll move my posts on this project to the SmX thread.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/13104878
> 
> 
> Dan, there's only one kind of 703. I am using it unfaced. Here's the submittal data sheet .



Actually there is the 1", 2", 3", 4", and 6". Which are you working with? It doesn't look like the 1" but pictures can be deceiving.


Thanks,

Dan


----------



## SteveMo

If I am hanging small traps from the wall to the ceiling at the sides of my front rows seating, can I place speakers nearby under them? My ceiling is 7' 6" and I am interested in placing whatever size I can fit there that may be effective but I would also like to correctly place Crystal Acoustics THX-Dipole speakers. Any other advise related to acoustics or my room I am working with while I have the available funds?


----------



## SteveMo

I have 12" traps in the front and back corners and areas around my room are made using fiberglass insulation and plywood. The PVC ceiling (with diffusion) is filled with fiberglass insulation and Roxul 60 above the front row. I also have Roxul 60 in the corner of the rear ceiling. I have 6 Berkline 88 leather seats. I got the result bellow after adding the traps in the corners, and before adding 6 24X24X2" Roxul panels with hardboard backing hung using Velcro in the front of the room.











I was thinking of ordering 12x44x1" open back panels X 2 for the left and right walls, and 12x53x1" open back panels X 2 for the rear wall. They would be ATS panels. Will this help improve the acoustics of the room? Should I do further testing first? I hear some problems in these areas with my mains turned down.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13106119
> 
> 
> Actually there is the 1", 2", 3", 4", and 6". Which are you working with? It doesn't look like the 1" but pictures can be deceiving.



So sorry, Dan. It is 2" 703. IIRC, 4" cost more than twice 2", and 1" not much, if any, less and w-a-y more tedious. If you look at the faces of my traps, you can see that they got more uniform as I became better with the electric turkey carver.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/13107423
> 
> 
> So sorry, Dan. It is 2" 703. IIRC, 4" cost more than twice 2", and 1" not much, if any, less and w-a-y more tedious. If you look at the faces of my traps, you can see that they got more uniform as I became better with the electric turkey carver.



Nothing to apologize for. I should have asked the thickness. Interesting idea on the electric turkey carver.


I have over half a roll of Linacoustic RC 1" left-over and am thinking of trying your idea in the front corners.


Thanks,

Dan


----------



## yngdiego




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13108469
> 
> 
> Nothing to apologize for. I should have asked the thickness. Interesting idea on the electric turkey carver.
> 
> 
> I have over half a roll of Linacoustic RC 1" left-over and am thinking of trying your idea in the front corners.
> 
> 
> Thanks,
> 
> Dan



I used an electric turkey carver as well and it worked great. The cuts weren't perfectly straight but since they aren't showing, it didn't matter. I actually got the Knauff version of OC703 and it works just fine, as well.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13108469
> 
> 
> Nothing to apologize for. I should have asked the thickness. Interesting idea on the electric turkey carver.
> 
> 
> I have over half a roll of Linacoustic RC 1" left-over and am thinking of trying your idea in the front corners.
> 
> 
> Thanks,
> 
> Dan



Did you look at Bob Gold's Absorption Coefficients ? The stuff you have tests similarly to 1" of the 703, so stacking it in wedges should give you similar performance. I have the 2" Linacoustic and will be re-hanging it behind the false wall after I wire the speakers and before hanging the screen.


----------



## Dan Woodruff

I noticed the similarities. I'm not sure I'll run out and get a turkey carver but it looks like wedge cutting is in my near future.


Thanks,

Dan


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13109236
> 
> 
> I noticed the similarities. I'm not sure I'll run out and get a turkey carver but it looks like wedge cutting is in my near future.
> 
> 
> Thanks,
> 
> Dan



I bought it for a song on eBay six to nine months ago for this project. There are a boatload of them there right now . . .


----------



## scientest




> Quote:
> Originally Posted by *pepar* /forum/post/13101855
> 
> 
> If I do up a corner and continue across the ceiling/wall corner, I would "miter" them for a continuous appearance. Is there something gained, performance-wise, by placing a cube in the corner, or is that just an aesthetic design element?
> 
> 
> edit: I'll bet the cube was their way of avoiding mitering . .



That's an interesting question; given that the corner is the _one_ place where you have all three axial modes (length, width, height) there might be more to it than avoiding mitering? I'd guess (and guess it is) that the extra depth of the cube will help with more of the lower frequencies than if you simply miter.


----------



## nathan_h




> Quote:
> Originally Posted by *bpape* /forum/post/13098927
> 
> 
> Nathan
> 
> 
> I sent you a PM. If we've missed something, I apologize. We try to return all calls the same day. PM me with your phone number and I'll be happy to work with you to figure out your needs.
> 
> 
> Bryan



Thanks! Talked with Glenn on the phone for a minute. He confirmed that the 244s are not as absorptive on the high end as the 242s, by design. That makes sense.


He was also able to forward me your email which I now see was eaten by my spam filter! I've left a msg for you this afternoon to ask a couple of questions about your email.


You've recommended all bass trapping and that may be the week point in my room (about 12.5 ft by 16 ft x 7.5 tall, sealed) but I've already got six real traps, and the wife hates the look of the aurlex foam at the first reflection points, so I'm thinking I may want some 242s to replace the foam, before anything else.


Hopefully we'll connect by phone soon and we can close the deal.


UPDATE: Spoke with Bryan and he patiently worked through a scenario that will optimize my room, make use of my existing treatments, and meet my budget (by splitting up the ideal purchases into two phases). I'm actually going to start with what he called phase 2, which acoustically is less of a big impact, because it will have the highest WAF (be more visually noticeable).


----------



## pepar

OK, one last post on my superchunk bass trap installation -


The area behind the false wall is complete; the 2" Linacoustic is back up covering the entire cavity, including the newly installed chunk traps. The dual Hsu's TN-1220HO's are back in place at 1/3 the room width at that part of the room and I did a quick spkr level calibration. No screen yet, but to get audio from the BD30 I needed to fire up the video chain, too. Wanting to hear music with a solid bottom, I popped the Sade live concert DVD-Video in and selected DD5.1. It was certainly not much of a test as I could not sit back in my main listening/viewing chair due to the screen frame members lying across the back, and I wanted/expected to hear an improvement, but nonetheless I _swear_ that I heard one - and a substantial one at that. Every bass note is now distinct, punchy and a discrete musical event. (My room was very flabby from 100Hz to 300Hz before with two serious nulls below 100Hz.) I listened to most of two or three songs before switching to my Denon 3910 and Gaucho on DVD-A. Wow! Granted, it would easier to determine if I really completely smoothed the bottom end if the bass player walked from his lowest note up the scales to his highest note, but again every note was clean, clear and oh sooo solid with no notes standing out or receding back.


When I get the screen up and the false wall buttoned up with velcro-attached panels I'll have a fellow HT enthusiast over with some audio test gear to "see" what the room's doing. I may not need to install any more chunk traps.


----------



## bpape




> Quote:
> Originally Posted by *SteveMo* /forum/post/13106960
> 
> 
> I have 12" traps in the front and back corners and areas around my room are made using fiberglass insulation and plywood. The PVC ceiling (with diffusion) is filled with fiberglass insulation and Roxul 60 above the front row. I also have Roxul 60 in the corner of the rear ceiling. I have 6 Berkline 88 leather seats. I got the result bellow after adding the traps in the corners, and before adding 6 24X24X2" Roxul panels with hardboard backing hung using Velcro in the front of the room.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I was thinking of ordering 12x44x1" open back panels X 2 for the left and right walls, and 12x53x1" open back panels X 2 for the rear wall. They would be ATS panels. Will this help improve the acoustics of the room? Should I do further testing first? I hear some problems in these areas with my mains turned down.



Steve.


Don't know what your room is like size wise so hard to be exact. I'd recommend playing with a couple of 6" thick panels centered on the rear wall of the room to see if that will impact your bottom end response.


As for the side panels, they're important for reflection duties and general decay time. Whether they should be 1 or 2" depends on a lot of other factors.


Bryan


----------



## SteveMo

Bryan,


I will do more testing. I have perfect towers and it is very scientific results for any speakers I may put in there.







I will try with the sub only and use the SPL configuration file. I will probably end up doing the kind of traps you suggested since I read so many good reviews about them. I was looking at those last week and I could now afford those. There is about 4' 1/2" height from the rear platforms to the crown molding. I will look more into it.


1. Size


The attached SketchUp images have the exact dimensions shown. I did this after the room was built and I double (before carpet) & triple checked so I could have a nice 3d model.


2. Current room treatments


The front of my room has some of these traps I made using 4lb Roxul 60 and dowel rods covered in two layers of burlap. From the top dowel rod up, the Roxul is stacked corners, bellow it is put into the frame with the shiny looking side facing out. There are 3 cut vertical compressed with some tiny pieces behind those to fill in gaps. I forced the Roxul 60 in very tightly and during that I had to reinforce my framing with larger deck screws to keep it from coming out the wall even though I used caulk behind the furring strips. I set the dowel rods in (after testing with different configurations) using Elmers high performance wood glue and filled in the holes I drilled out on each side using wood filler afterwards. I painted the frames because I was bored while it was all drying for about a day or two.











It looks like this but I have been trying to touch up the trim using caulk more recently.











There are some in the rear of the room the same but without dowel rods being used since they were short and pretty strong to begin with. Those are between the platforms and the ceiling.


I have four 24X24X2" panels (Roxul AFB mineral wool, 1/4-inch wood back panel, industrial strength Velcro, burlap) for first reflection points I positioned using the mirror method post construction and after. I also have one just sitting behind my sub-woofer, but not the center channel. They need more Velcro. The sub is on a sub dude for isolation.


The walls are a "knock down" finish and are covered with lots of primer and paint. The walls are filled with R45 (if I remember right) and the other areas are filled using R19 that I (with help) removed the paper off of. We went through many rolls of various fiberglass insulation for the entire room. We ran out for the riser and so the center cavity is only 1/3 full. The rear wall was left uncompleted (without insulation at the bottom & drywall) to where I can stuff insulation in there later, fill with sand, or whatever I need to use to place a sub on it. The unfinished area is between the left and right rear platforms. The main reason it wasn't finished was so that I could move my wall plates later on when those go to the equipment closet.


The rear platform area is lined with the insulation but next to the wall it is not . I had nothing to put there. I put holes in the face of the plywood cavity before carpeting. I'm not sure the exact size and I haven't yet really looked into the frequency at which it resonates much. Anyone know if I should line the back wall with something or just blow in some insulation?


----------



## cpc

Hey, what do you guys think of sonex acoustic sound panels?


----------



## SteveMo

My testing didn't get real into much detail this time. The MACC setup on my AVR wouldn't even give me the OK for a setup even after I tried propping up the RS digital mic. I tried both left and right inputs and didn't bother to hunt down the Y connector. I thought about using REW again maybe with the correct settings at least for the program but thought it might not be worth the effort if I can't turn off bass management. I tried DVE only to find that my sub wasn't even played on the HD-DVD side, so I flipped that over and used the DVD. I ran sweeps and put the SPL meter in different locations and it looked decent. After I listened to both left and right mains in the rear of the room it all kind of just blurs together under 100Hz. Using half the spikes for each speaker to aim them seems to really hurt down low. I put the SPL meter to A weighting and checked both the front row and then the back. I checked again with the SPL meter a couple feet from the rear wall and it was really spiking from 78Hz to about 83Hz with the sub. The mains were just spiking all over the place there after about a 100. When I had the towers sitting on the side platforms even when not in use, they would make the ceiling above it rattle. I didn't check that with DVE but discovered the issue with movies pretty fast after I quit using them for 5.1 analog use. The sub seems to rattle the front tower speakers.


Does this look OK or do I need smaller? I scaled the speakers down to the correct size. I can't separate them much more or one aims directly at a beam.


----------



## Terry Montlick




> Quote:
> Originally Posted by *cpc* /forum/post/13165474
> 
> 
> Hey, what do you guys think of sonex acoustic sound panels?



Sonex panels work, but not as efficiently as semi-rigid fiberglass for the 2" variety. It may be that the contoured shape of the foam simply lowers the average thickness too much. The thick 3" Sonex performs pretty well, and the 12" thick wedges can make a nice anechoic chamber.










If you found a great buy on Sonex and you like the look, consider using it. One advantage is that it doesn't need to be covered with fabric to look decent. Otherwise 2 1/4 to 6 pcf fiberglass (OC 703, OC 705, Linacoustic, etc.) is the way to go, giving the most absorption bang for the thickness buck -- at least for the thinner (2") products.


Regards,

Terry


----------



## cpc




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13166865
> 
> 
> Sonex panels work, but not as efficiently as semi-rigid fiberglass for the 2" variety. It may be that the contoured shape of the foam simply lowers the average thickness too much. The thick 3" Sonex performs pretty well, and the 12" thick wedges can make a nice anechoic chamber.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If you found a great buy on Sonex and you like the look, consider using it. One advantage is that it doesn't need to be covered with fabric to look decent. Otherwise 2 1/4 to 6 pcf fiberglass (OC 703, OC 705, Linacoustic, etc.) is the way to go, giving the most absorption bang for the thickness buck -- at least for the thinner (2") products.
> 
> 
> Regards,
> 
> Terry



Thanks. A guy is selling some pre-made sonex panels, so I was curious. Of course, I can always get some sonex myself, and there is the other stuff you mention, so I'll look into it....and I'll check out your site too










thanks,


----------



## bpape

Steve


Any uninsulated wall should be done. Blown in is fine but fill it up.


As for the panels on the back, that can certainly help. I was suggesting just trying to sit them there as a test.


Bryan


----------



## SteveMo

I spoke with Bryan the other day. I decided to try the GIK 244 Bass Traps on the back wall. I will also test them on the front wall but I only have 19" between the traps and the screen so I would require custom sized ones there later on if I find them to help. It would be nice to cover up those speaker plates. The LCR are 8' from the middle seat, and the towers are about 1' 10" from both walls in the photo. The center channel is about 3" from the wall from where it's bass ports are sticking out the back. I could place some under the screen and behind the center channel maybe also. I got set straight about the ATS bass traps and a few other issues. It gets very confusing sometimes. Thanks Bryan!


----------



## cpc




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13166865
> 
> 
> Sonex panels work, but not as efficiently as semi-rigid fiberglass for the 2" variety. It may be that the contoured shape of the foam simply lowers the average thickness too much. The thick 3" Sonex performs pretty well, and the 12" thick wedges can make a nice anechoic chamber.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If you found a great buy on Sonex and you like the look, consider using it. One advantage is that it doesn't need to be covered with fabric to look decent. Otherwise 2 1/4 to 6 pcf fiberglass (OC 703, OC 705, Linacoustic, etc.) is the way to go, giving the most absorption bang for the thickness buck -- at least for the thinner (2") products.
> 
> 
> Regards,
> 
> Terry




Any idea where I can find Linacoustic or any of the other products online or otherwise? I am in Toronto, Canada.


thanks,


----------



## yngdiego

I'm trying to figure out a good way to mount 2x4' OC703 panels diagonally along the sides of the room where the wall meets the ceiling. I got some Rotofast cloud hangers that worked well for my horizontal clouds.


However, trying to use them for a diagonal mount isn't working too well. I put two U shaped hooks in the ceiling near the wall and ran some string through two sets of two cloud mounts up to the hooks, forming a triangle for each support. However, trying to get the string length just right so the panel is snug against the wall/ceiling is tough. Plus, it's pulling the Rotofast anchors at weird angles and I fear they will pull out.


So now I'm thinking about a couple of small but deep brackets/hooks that would go on the wall under the bottom to support the weight, and some type of hook deal in front of the panel on the ceiling to hold the top up.


The panels are just plain OC703 which I covered in tan GOM. So there's no real structure to the panel that I can anchor from behind. I'll go to home depot tomorrow, but wanted some input first.


Thanks!


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/13213087
> 
> 
> I'm trying to figure out a good way to mount 2x4' OC703 panels diagonally along the sides of the room where the wall meets the ceiling. I got some Rotofast cloud hangers that worked well for my horizontal clouds.
> 
> 
> However, trying to use them for a diagonal mount isn't working too well. I put two U shaped hooks in the ceiling near the wall and ran some string through two sets of two cloud mounts up to the hooks, forming a triangle for each support. However, trying to get the string length just right so the panel is snug against the wall/ceiling is tough. Plus, it's pulling the Rotofast anchors at weird angles and I fear they will pull out.
> 
> 
> So now I'm thinking about a couple of small but deep brackets/hooks that would go on the wall under the bottom to support the weight, and some type of hook deal in front of the panel on the ceiling to hold the top up.
> 
> 
> The panels are just plain OC703 which I covered in tan GOM. So there's no real structure to the panel that I can anchor from behind. I'll go to home depot tomorrow, but wanted some input first.
> 
> 
> Thanks!



You may not judge this method suitable for locations that can be seen, but here is my post from earlier in this thread . The "finished" result is pictured some posts after it. It is extremely simple and inexpensive.


----------



## nathan_h

Continuing my saga of replacing the panels that the lady of the house didn't like the look of with something more acceptable.... The GIK panels (model 242) arrived and she likes them! Hey, that's great. Gonna order a second set, soon.


I posted photos in my dedicated construction thread -- http://www.avsforum.com/avs-vb/showt...5#post13216725 -- but since one thing I couldn't find when planning to order some panels were good CLOSE UP photos of them, I'm cross posting those photos, here.


They are black, but the flash washes out the color and shows through the GOM fabric (an upgrade) to the structure underneath. Even under direct sunlight you cannot actually see anything under the GOM. I'm not sure what the default GIK cloth looks like. I decided I wanted to get the "best" covering right out of the gate, in order to make sure I please "she that must be obeyed."


I may try out the standard fabric on the next order and see what that is like and whether she likes it.


The picture hanging wire on the one where you see the back hasn't been tightened on for use, yet.


(For the record: The Auralex foam is slowly be sold on craigslist. Two boxes were never even mounted! But she hates foam and that was the biggest complaint from her about the whole theater... not the black room or anything else. And the Real Traps were sold not because they were ineffective -- far from it -- and of course they are built like tanks -- but because she prefers the "all fabric" look. Almost think I should have just covered the Real Traps in some GOM but it's too late now.)


----------



## Avatar8481

I have two unopened bales of the 703 material in the one inch variety. I have enough room in the theater that I could literally just sit them in the corners of the room as dense absorbers? Would that be productive, or does the material only work if it's had a chance to expand to its unpacked dimension (2x4x1inch) If I do unpack it, my read of the thread is that there isn't a reason, other than aesthetics to go with angled 'chunks' rather than a cube?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *Avatar8481* /forum/post/13217990
> 
> 
> I have two unopened bales of the 703 material in the one inch variety. I have enough room in the theater that I could literally just sit them in the corners of the room as dense absorbers? Would that be productive, or does the material only work if it's had a chance to expand to its unpacked dimension (2x4x1inch) If I do unpack it, my read of the thread is that there isn't a reason, other than aesthetics to go with angled 'chunks' rather than a cube?



I don't think there's much to be gained by having a BIG square column from floor to ceiling over having a half-as-big TRIANGULAR column from floor to ceiling. And there's TWO of the latter in the former.


----------



## Avatar8481

that makes sense, twice as much material for the same amount of money and a triangle isn't half as effective as a cube, so why not. I guess I was trying to avoid having to make lots of cuts, but the electric knife idea is a good one, maybe I'll try that.


----------



## SteveMo

I actually used two electric turkey knives. The first one I used was from the 1950's - 1970's and ran for less than half a minute. The second "good turkey knife" started getting dull after about a third of the way though and was no longer cutting as well. I used the good ones for the corners and used my scraps elsewhere.


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/13220938
> 
> 
> I actually used two electric turkey knives. The first one I used was from the 1950's - 1970's and ran for less than half a minute. The second "good turkey knife" started getting dull after about a third of the way though and was no longer cutting as well. I used the good ones for the corners and used my scraps elsewhere.



My new knife got very warm and smelled a bit almost immediately. I pressed on and cut about a one and a half bales of 703. Got some good wrist workouts in the process.


----------



## AZGAMD

Any ideas for a 4'wx6'l window? I don't want to cover it with framing and drywall, but don't mind putting something over it. I was thinking of an acoustic treatment and mirror another opposite it on the other wall. Any other ideas?


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/13222243
> 
> 
> My new knife got very warm and smelled a bit almost immediately. I pressed on and cut about a one and a half bales of 703. Got some good wrist workouts in the process.



I used a cheapo $15 one from Wal-Mart and I cut two bales without issue. It did get somewhat warm, but never smoked and I didn't notice it getting dull.


----------



## HuskerHarley

Is OC better than BAC for corner traps?


HH


----------



## pepar




> Quote:
> Originally Posted by *HuskerHarley* /forum/post/13225142
> 
> 
> Is OC better than BAC for corner traps?



It's the density that matters, not the manufacturer.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/13225259
> 
> 
> It's the density that matters, not the manufacturer.



True for fiberglass. But for different materials, like BAC (bonded acoustic cotton), you really have to compare flow resistivity.







Some porous materials are essentially equivalent in flow resistivity for a given density, and this just *happens* to be true for fiberglass and acoustic cotton. But this is not the case with rockwool, for example.


Regards,

Terry


----------



## HuskerHarley




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13225434
> 
> 
> True for fiberglass. But for different materials, like BAC (bonded acoustic cotton), you really have to compare flow resistivity.
> 
> 
> 
> 
> 
> 
> 
> Some porous materials are essentially equivalent in flow resistivity for a given density, and this just *happens* to be true for fiberglass and acoustic cotton.



Should I shop the price not the product between OC & BAC?


HH


----------



## Terry Montlick




> Quote:
> Originally Posted by *HuskerHarley* /forum/post/13225734
> 
> 
> Should I shop the price not the product between OC & BAC?
> 
> 
> HH



Yes, but don't restrict yourself to Owens Corning. The other fiberglass manufacturers of the world:


CertainTeed

Johns Manville

Knauf


Regards,

Terry


----------



## HuskerHarley

Thanks Terry.


HH


----------



## tleavit

Window plug.


I can’t go into too much detail because it might violate forum rules.


I just got a quote for a pretty nice window plug from an acoustical company for my front window. Its a 5' x 5' window. They will include a custom 2" of sound paneling on the side facing the HT. They want $1100 for it. Seems a bit high. I’ve been acquiring 2' x 4' x 4" paneling from an AVS selling for $70ish bucks each. But I could really use that thing and its made pretty nice. The window is smack in the middle of my front reflection point so having the panel on t would really help out sound. Right now I lean a panel up against the window. Below is the best pic I got right now. The plug would also help out a lot on some minor lighting streaks that get through the curtains (at the folds) during the day onto the screen.


Any good opinions out there?


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/13228037
> 
> 
> Window plug.
> 
> 
> I can't go into too much detail because it might violate forum rules.
> 
> 
> I just got a quote for a pretty nice window plug from an acoustical company for my front window. Its a 5' x 5' window. They will include a custom 2" of sound paneling on the side facing the HT. They want $1100 for it. Seems a bit high. I've been acquiring 2' x 4' x 4" paneling from an AVS selling for $70ish bucks each. But I could really use that thing and its made pretty nice. The window is smack in the middle of my front reflection point so having the panel on t would really help out sound. Right now I lean a panel up against the window. Below is the best pic I got right now. The plug would also help out a lot on some minor lighting streaks that get through the curtains (at the folds) during the day onto the screen.
> 
> 
> Any good opinions out there?



You could build one yourself. Is that what you're asking?


----------



## tleavit




> Quote:
> Originally Posted by *pepar* /forum/post/13228127
> 
> 
> You could build one yourself. Is that what you're asking?



No, I dont have the skills, tools or drive to build one myself. Im better at building servers.


----------



## yngdiego




> Quote:
> Originally Posted by *tleavit* /forum/post/13228774
> 
> 
> No, I dont have the skills, tools or drive to build one myself. Im better at building servers.



Stack some servers up in the window..vertically.


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/13228774
> 
> 
> No, I dont have the skills, tools or drive to build one myself. Im better at building servers.



Then you better build enough of them to clear $1100.


----------



## penngray

Im having problems sourcing linacoustic RC, fibre glass insulation.


My HVAC guys are wondering if other fibre glass insulation products will work. Is it just a measurement of thickness and R rating? They have other products that are 4x8 sheets, 1" thick and have a R rating of 4 or close to it. They have CertainTeed products and its not rolls but boards so its even easier to install (I think).


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13230990
> 
> 
> Im having problems sourcing linacoustic RC, fibre glass insulation.
> 
> 
> My HVAC guys are wondering if other fibre glass insulation products will work. Is it just a measurement of thickness and R rating? They have other products that are 4x8 sheets, 1" thick and have a R rating of 4 or close to it. They have CertainTeed products and its not rolls but boards so its even easier to install (I think).


 http://www.spi-co.com/


----------



## penngray

Thanks for the link but I still would like to know if different products do the same thing as linacoustic. I have connections with builders so I can get things near cost and no shipping costs, its cheaper for me if I can get some locally.


lol, I could re-read the first page and findout that Certainteed Certpro Acoustaboard Black is the same as linacoustic for sound


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13232659
> 
> 
> Thanks for the link but I still would like to know if different products do the same thing as linacoustic.



Density (not R value) and thickness determine acoustic performance for fiberglass duct liner. Linacoustic has a density of about 2.25 pcf, but I think compares well to 3 pcf fiberglass because of its inner fiber-sealing layer. All 3 pcf insulation is generically termed "type 300", and is essentially equivalent, regardless of manufacturer.


Regards,

Terry


----------



## penngray




> Quote:
> Density (not R value) and thickness determine acoustic performance for fiberglass duct liner. Linacoustic has a density of about 2.25 pcf, but I think compares well to 3 pcf fiberglass because of its inner fiber-sealing layer. All 3 pcf insulation is generically termed "type 300", and is essentially equivalent, regardless of manufacturer.



Thanks! Is it okay to go with 1" 3 pcf? The certaPro Acoustaboard Black has two densities 2.25 and 3.00, Im just confused on which one I should order tomorrow.


----------



## BasementBob

penngray:


You can compare a lot of things, here: http://www.bobgolds.com/AbsorptionCoefficients.htm 

find "CertainTeed" on that page.


If you find absorption coefficients for a product that isn't on that page, just let me know.


----------



## Shock96

Whew! I can't believe I ate the whole thing...101 pages, 3017 post, 3 days.


I have specific questions for the pro's on there so I will start a threat with a Visio drawing of my space and the "plan".


Thanks for all the great info everyone!


mike


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13233074
> 
> 
> Thanks! Is it okay to go with 1" 3 pcf? The certaPro Acoustaboard Black has two densities 2.25 and 3.00, Im just confused on which one I should order tomorrow.



The difference is pretty minimal. While absorption coefficients are reported to 2 decimal places, the margin of error for the standard reverberation room method used limits the accuracy to something only slightly better than 1 decimal place. In theory, the 3 pcf should absorb a bit more at 250 to 500 Hz than the 2.25 pcf of the same area. In practice, I'm not sure at all that you could tell the difference. Check out the prices between the two, and go with the cheapest.


Regards,

Terry


----------



## penngray




> Quote:
> You can compare a lot of things, here: http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> find "CertainTeed" on that page.
> 
> 
> If you find absorption coefficients for a product that isn't on that page, just let me know.



Thanks for the link!!!


btw, My brother and best friend live just of Bronte Rd. in Oakville. Its a great city!!


----------



## AZGAMD

I need some experts to chime in. Would 2 layers of ~0.60-0.75" 1.5pcf fiberglass insulation work o.k. for acoustic panels? I am not sure of the manufacturer. I know it is not ideal to the 3-6pcf, but looking at the numbers for OC701 on Bob's site they do not look horrible. I have the ability to buy some old office cubicle walls very cheap and was wondering if I could use the insulation for acoustic panels. I was also thinking about using the wood from the panels for the frames. The wood alone is worth the price. The fabric covering them, which is a light tan, will not work for me so I would most likely sell it making them even cheaper. Is anyone interested? Does anyone have any thoughts/comments. I am looking for feedback to either help me make the decision to buy them or to just walk away if it would be too much work and not worth my time. Thanks in advance.


----------



## CruelInventions




> Quote:
> Originally Posted by *nathan_h* /forum/post/13216790
> 
> 
> Continuing my saga of replacing the panels that the lady of the house didn't like the look of with something more acceptable.... The GIK panels (model 242) arrived and she likes them! Hey, that's great. Gonna order a second set, soon.



Thanks for the pics, though they may have served only to dissuade me from ordering those from GIK. They're a little too amateurishly "lumpy" in the corners, due to material folding at the ends. Granted, they appear to make them about as well as you'll ever see for this type of construction style. I've seen enough cheesy DIY examples of this type of 2' x 4' treatment and GIK DOES put most of those to shame, but perhaps still not quite taut or crisp-looking enough for my tastes. Then again, theirs are a bit cheaper in price than some of the other ones I am thinking of, so everything is a trade off, I suppose.


I wonder if their tri-traps are a little "tighter" looking? I think the material folded ends are hidden below the end caps, so those might provide a tidier look that I am more disposed to liking.


----------



## penngray

Someone has suggest that I will be okay if I run the acoustic on 100% of my walls and if I do that I should add some bass traps to the ceiling (by the screen) and on the back wall (probably corners too).


I have read here that its not good to run acoustic sound absorption stuff on 100% of the wall so which is it?


My HT build thread..... http://www.avsforum.com/avs-vb/showthread.php?t=1000239


----------



## yngdiego




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13242918
> 
> 
> Thanks for the pics, though they may have served only to dissuade me from ordering those from GIK. They're a little too amateurishly "lumpy" in the corners, due to material folding at the ends.



I too thought those corners were pretty lumpy. I built several 2x4 panels covered in GOM, and I got the corners looking much better. Basically along the two short ends I have a single "triangle" fold that is glued down.


It's not rocket science, but if I had paid for pre-made panels and gotten lumpy corners like that I would have returned them.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13244990
> 
> 
> Someone has suggest that I will be okay if I run the acoustic on 100% of my walls and if I do that I should add some bass traps to the ceiling (by the screen) and on the back wall (probably corners too).
> 
> 
> I have read here that its not good to run acoustic sound absorption stuff on 100% of the wall so which is it?



The latter. Rooms become too deadened long before their walls are 100% covered.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/13245252
> 
> 
> I too thought those corners were pretty lumpy. I built several 2x4 panels covered in GOM, and I got the corners looking much better. Basically along the two short ends I have a single "triangle" fold that is glued down.
> 
> 
> It's not rocket science, but if I had paid for pre-made panels and gotten lumpy corners like that I would have returned them.



Some commercially available panels are made from fiberglass batts with edges/corners which have been chemically hardened. Those are "cleaner" looking, but are m-o-r-e expensive. This design is not practical for DIY. The only design remaining that will produce a more, um . . finished look with taut covering is one with a frame and a back.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/13245378
> 
> 
> Some commercially available panels are made from fiberglass batts with edges/corners which have been chemically hardened. Those are "cleaner" looking, but are m-o-r-e expensive.



Yes. And even for these, it is best to stick to the denser, most rigid fiberglass -- OC 705 or other 6 pcf material.


Regards,

Terry


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/13245378
> 
> 
> Some commercially available panels are made from fiberglass batts with edges/corners which have been chemically hardened. Those are "cleaner" looking, but are m-o-r-e expensive. This design is not practical for DIY. The only design remaining that will produce a more, um . . finished look with taut covering is one with a frame and a back.



I will say that using the fiberglass resin from home depot on the edges did work pretty well. Using tan colored GOM, you can see the edges aren't perfectly square because the resin didn't apply perfectly. On the black GOM covered panels it looks really awesome.


I'm a perfectionist, but I do think the resin route works well for a DIY method. If it didn't cure so darn fast then the edges could be even more square. I mixed it in 8oz batches and working time was maybe 5-7 minutes, tops. 8oz covered about three sides of a 2x4' panel.


Odor is HORRIBLE so get a good VAC mask or you might pass out or suffer brain damage.










Update: By accident I found some much slower curing epoxy that someone might want to use instead of the home depot stuff. http://www.tapplastics.com/shop/product.php?pid=27& The "Slow" version has a 30-minute pot life which would make it vastly easier to apply it in a more controlled and careful manner.


----------



## SteveMo

Here are some black GIK 244 Bass traps. 2'x 4' Acoustic 4" Panel (5.5" total thickness). I picked them up at my neighbors and borrowed his wheel barrow. I have not been feeling well and I missed delivery, but they have arrived. The other day I hooked up my speakers to both sets of in-wall wire and ran some wire from the plates (I am spray painting with satin black Krylon) to my speakers using only my separates as amplification. I didn't explain what I had done...but I had a comment that the pitch had changed, and that the bass seemed to be coming from the back of the room more. I had explained afterwards that these were on the way. Hope they like them.


----------



## nathan_h




> Quote:
> Originally Posted by *yngdiego* /forum/post/13245252
> 
> 
> I too thought those corners were pretty lumpy. I built several 2x4 panels covered in GOM, and I got the corners looking much better. Basically along the two short ends I have a single "triangle" fold that is glued down.
> 
> 
> It's not rocket science, but if I had paid for pre-made panels and gotten lumpy corners like that I would have returned them.



Well, I didn't take them apart to see but I *think* though they have a nice wood frame in the back -- that helps with rigidity and hanging, and adds an air space between the panel and the wall -- the edges and corners of the front are fiberglass. I guess that might mean they don't stay as square as they should be.


Or did I get some damaged goods? The shipping may have messed with them a bit. I guess I should ask the GIK guys. They've been helpful throughout the process. Looking at SteveMo 's pictures, the top/bottom edges don't look totally square, either....


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/13245720
> 
> 
> I will say that using the fiberglass resin from home depot on the edges did work pretty well. Using tan colored GOM, you can see the edges aren't perfectly square because the resin didn't apply perfectly. On the black GOM covered panels it looks really awesome.
> 
> 
> I'm a perfectionist, but I do think the resin route works well for a DIY method. If it didn't cure so darn fast then the edges could be even more square. I mixed it in 8oz batches and working time was maybe 5-7 minutes, tops. 8oz covered about three sides of a 2x4' panel.
> 
> 
> Odor is HORRIBLE so get a good VAC mask or you might pass out or suffer brain damage.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Update: By accident I found some much slower curing epoxy that someone might want to use instead of the home depot stuff. http://www.tapplastics.com/shop/product.php?pid=27& The "Slow" version has a 30-minute pot life which would make it vastly easier to apply it in a more controlled and careful manner.



If I was going this route, I'd experiment with some kind of a form to hold the edges while the resin hardened. As crisp as the commercial ones are, I'd bet they're using some kind of mold.


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/13255248
> 
> 
> If I was going this route, I'd experiment with some kind of a form to hold the edges while the resin hardened. As crisp as the commercial ones are, I'd bet they're using some kind of mold.



I"m sure they do use some type of mold. The but the resin is so tacky, that I would think any type of form would have to be teflon coated. But given the longer working time, I think it would be possible to get pretty good coverage and then sand the edges once it has hardened. Too bad I didn't find this stuff until I was completed with all my panels.


----------



## pepar




> Quote:
> Originally Posted by *yngdiego* /forum/post/13256662
> 
> 
> I"m sure they do use some type of mold. The but the resin is so tacky, that I would think any type of form would have to be teflon coated.(



I'm thinking a "wax paper" lined mold.


----------



## AZGAMD




> Quote:
> Originally Posted by *pepar* /forum/post/13257291
> 
> 
> I'm thinking a "wax paper" lined mold.



We use a "teflon" tape at work all the time for curing epoxy samples. It works very well.


----------



## pepar




> Quote:
> Originally Posted by *AZGAMD* /forum/post/13261780
> 
> 
> We use a "teflon" tape at work all the time for curing epoxy samples. It works very well.



Is that like tape used by plumbers on threaded pipes? Wider, maybe?


----------



## AZGAMD




> Quote:
> Originally Posted by *pepar* /forum/post/13264216
> 
> 
> Is that like tape used by plumbers on threaded pipes? Wider, maybe?



No, it has adhesive on one side and is a clear brown in color. I honestly have no idea where you could even find it, but it is very useful.


----------



## nathan_h




> Quote:
> Originally Posted by *nathan_h* /forum/post/13254051
> 
> 
> Well, I didn't take them apart to see but I *think* though they have a nice wood frame in the back -- that helps with rigidity and hanging, and adds an air space between the panel and the wall -- the edges and corners of the front are fiberglass. I guess that might mean they don't stay as square as they should be.
> 
> 
> Or did I get some damaged goods? The shipping may have messed with them a bit. I guess I should ask the GIK guys. They've been helpful throughout the process. Looking at SteveMo 's pictures, the top/bottom edges don't look totally square, either....



Here are some new photos, with the panels mounted (well, the ones behind the couch aren't really mounted in their final spot, since they'll move to the side walls, and I'll place a couple of 244s behind the couch where you see these). I'm thinking they look pretty good


----------



## penngray

I want to make corner wall bass traps and I have OC 703 1" on order. Can I double the 1" up to make 2" in the corners does this help with Bass sound absorption? Or should I just order OC 705?


----------



## eugovector

My understanding: 703 is fine, but you should use 4" straddling the corners.


----------



## penngray

so correct me if Im wrong....


1" OC 703 100% of the front wall.


1" OC 703 around the bottom of the side and rear walls, 4' high?


4" OC 703 in the corners


and maybe a couple 2x4 1" panels on the celing close to the front wall? My ceiling is drywall and will be painted. I will fabric the side walls. My floor will be carpet.



Also, my room is just a frame so I can maybe add more framing at 45 degree angles with 2x4s to each corner and then it would be easier to apply OC 703 to the corners??


----------



## dododge




> Quote:
> Originally Posted by *AZGAMD* /forum/post/13265005
> 
> 
> No, it has adhesive on one side and is a clear brown in color. I honestly have no idea where you could even find it, but it is very useful.



FWIW McMaster-Carr seems to have a variety of such tapes .


----------



## penngray

I would like to cover my OC 703 (just purchased 12 2x4x1 sheets from ebay for $130 shipped) with Dazian Blackout satin coth (100% Polyester )


would this cause any problems?

http://www.dazian.com/cgi-bin/page.p...=119&cat_id=45


----------



## eugovector

I know Dazian makes acoustically transparent fabrics, but I don't think this is one of them.


And, generally speaking, are man-made fibers more likely to reflect highs rather then pass them through to be absorbed by the panels?


----------



## yngdiego




> Quote:
> Originally Posted by *penngray* /forum/post/13271711
> 
> 
> so correct me if Im wrong....
> 
> 
> 1" OC 703 100% of the front wall.
> 
> 
> 1" OC 703 around the bottom of the side and rear walls, 4' high?
> 
> 
> 4" OC 703 in the corners
> 
> 
> and maybe a couple 2x4 1" panels on the celing close to the front wall? My ceiling is drywall and will be painted. I will fabric the side walls. My floor will be carpet.
> 
> 
> 
> Also, my room is just a frame so I can maybe add more framing at 45 degree angles with 2x4s to each corner and then it would be easier to apply OC 703 to the corners??



I think people would agree that building "super chuncks" for bass traps in the corner is somewhat more effective than just placing full sheets diagonally across and leaving a free space cavity behind them. "Super chunk" is basically a stack of triangle shaped OC70x stacked up so that it's a solid corner. It's more work to get installed, but gives you more material for increased sound deadening.


----------



## penngray




> Quote:
> full sheets diagonally across and leaving a free space cavity behind them. "Super chunk" is basically a stack of triangle shaped OC70x stacked up so that it's a solid corner. It's more work to get installed, but gives you more material for increased sound deadening.



So if I build triangle frames and fill them with OC703, I should get a decent bass traps. That is what Im thinking of doing. I will cut my OC703 to fill the triangle corner frames.



> Quote:
> I know Dazian makes acoustically transparent fabrics, but I don't think this is one of them.
> 
> 
> And, generally speaking, are man-made fibers more likely to reflect highs rather then pass them through to be absorbed by the panels?



I was hoping it wouldnt effect the absorption too much. The GOM stuff so far hasnt passed the wifes approval.


----------



## yngdiego




> Quote:
> Originally Posted by *penngray* /forum/post/13284167
> 
> 
> I was hoping it wouldnt effect the absorption too much. The GOM stuff so far hasnt passed the wifes approval.



What's wrong with GOM? I got their black and tan colors, and I'm very pleased with them. You can order samples and get a better feeling of the color. I got 8-9 samples and found two that were perfect.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13284167
> 
> 
> So if I build triangle frames and fill them with OC703, I should get a decent bass traps. That is what Im thinking of doing. I will cut my OC703 to fill the triangle corner frames.



You will not only get the best traps that a small amount of money can buy, you will get very close to the best traps that nearly any amount of money can buy.


----------



## SRR

 http://www.atsacoustics.com/item--Ro...f-6--RB60.html 


Is what I used for my bass traps, those sheets are 2" thick by 2'x4'. They measure very well compared to OC705 and are a good bit cheaper. And they stand up straight when leaned against a wall, unlike OC703. I use the Rockboard 60 in my studio as well. $60-$65 shipped for a box, +walmart fabric, +adhesive spray...hmmm, yummy. I did two 4" traps for the front corners on the floor going upwards and two 2" traps going from them towards my center speaker. Then I had some acoustic foam left over from a studio I worked in, and shoved them behind the 4" traps, probably doesn't help much, but if it gives a little more absorption all the better.


----------



## penngray




> Quote:
> What's wrong with GOM? I got their black and tan colors, and I'm very pleased with them. You can order samples and get a better feeling of the color. I got 8-9 samples and found two that were perfect.



I have no problems with it, its the WAF thing and she wants some input if Im "stealing" the bonus room and making it a HT










are there different textures of GOM?


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13288501
> 
> 
> I have no problems with it, its the WAF thing and she wants some input if Im "stealing" the bonus room and making it a HT
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> are there different textures of GOM?



There are, but you should limit your choices to the acoustically transparent fabrics.

http://www.silentsource.com/acoustic...lorchart1.html


----------



## penngray




> Quote:
> There are, but you should limit your choices to the acoustically transparent fabrics.



Man, there is so much reading and so many different opinions on this stuff.


I read that 100% polyester products allow substantially all the sound directed against the panel to pass into the glass fiber layers, the Dazian Blackout satin is 100% polyester



I also read that its not really acoustically transparent material we need for sound absorption but its material that does not reflect sound, as long as the material doesnt reflect much sound we are good.


I guess it comes down to how much reflection really happens because logically if the material is not acoustically transparent then it does reflect sound (atleast a little bit).


My freaking head hurts...Atleast I think I got a good deal for OC703 and I just ordered Roxul Rockboard 60 for the bass traps. Things are coming together, I just wish I could figure out the fabric.


btw, Thanks for the link







Im going to order a sample of the Anchorage Style 2016 ONYX color


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13288941
> 
> 
> Man, there is so much reading and so many different opinions on this stuff.
> 
> 
> I read that 100% polyester products allow substantially all the sound directed against the panel to pass into the glass fiber layers, the Dazian Blackout satin is 100% polyester
> 
> 
> 
> I also read that its not really acoustically transparent material we need for sound absorption but its material that does not reflect sound, as long as the material doesnt reflect much sound we are good.
> 
> 
> I guess it comes down to how much reflection really happens because logically if the material is not acoustically transparent then it does reflect sound (atleast a little bit).
> 
> 
> My freaking head hurts...Atleast I think I got a good deal for OC703 and I just ordered Roxul Rockboard 60 for the bass traps. Things are coming together, I just wish I could figure out the fabric.



Yes, the problem is not that it doesn't pass frequencies, but that it might reflect them.


----------



## tleavit

I did this up pretty fast in MS paint. What do you guys think? The panels would be typical 4' x 2' x 4" acoustic panels with black GOM. When the screens down they would be hidden behind it. I'm thinking about placing 1 foot tube traps in the corners next.


----------



## eugovector

Don't forget you side, back, ceiling reflection points. With the screen down, you'll need some other absorption in the room.


----------



## tleavit




> Quote:
> Originally Posted by *eugovector* /forum/post/13291141
> 
> 
> Don't forget you side, back, ceiling reflection points. With the screen down, you'll need some other absorption in the room.



Ya, I already have 2 at the primary front reflection points (you can barely see one on the left, they aren't mounted yet, one is leaning on top of my sub). I'm slowly adding the panels as I can afford them. 2 went in the sides, Ill get 3 to 5 on the front next. Then I'll throw some up on the rear and then a few more on the sides and figure out what to do on the ceiling. I'll throw some tube base traps in the corners and call it as good as it can get in the room after that I recon.


----------



## penngray

pepar, again thanks for the link. I sent an email to silent source for some samples and they are sending them too me now. Great customer service!!!


----------



## TheTurk

I bought a package of 2" Rockwool and just made four 3" thick 2x4 frames. I will cover them with the GOM fabric. Questions is: Should I put a single sheet inside each frame or squeeze two sheets in each frame? Or should I go out and buy a 3" Rockwool package instead?


----------



## MTBDOC

Build 4" frames! Seriously, why did you do 3"...


----------



## pepar




> Quote:
> Originally Posted by *MTBDOC* /forum/post/13298585
> 
> 
> Build 4" frames! Seriously, why did you do 3"...



I had that same comment in the reply window two times and decided against posting it.










Adding another inch to the depth might be possible. I might also load two sheets in and try to cover it with GOM so that the "proud" rockwool got rounded over into nice edges.


----------



## tleavit

I did some more hard core measuring down there and came up with a new pattern. What do you guys think? Between the 2? Both give me space in the corner to put up tube bass traps. In the second picture, I threw in some sides that will go in also. To boot, when the screen is down, they will be hidden.














Or


(that panels actually slip behind the TV perfectly due to its mount)


----------



## eugovector

From my understaning, for the most part, the more coverage up front, the better. However, once again, won't most of this be rendered ineffective with the screen down?


----------



## BasementBob




> Quote:
> From my understaning, for the most part, the more coverage up front, the better.



In theory yes, in practice it's a change so somethings will sound better and some things not as good.


I did my entire front wall in 4" with a 4" air gap (8" total), and that's the way its been for a year and a half now.

Before I did that I remember listening to the closing credits of We Were Soldiers and just being in acoustic awe. It was a perfect moment. I had everyone I knew come by and listen, and they all heard and understood and commented on its accoustic wonderfulness. I played it over and over again while I was alone. Ummmm. Gooood.

Then I wrecked the room support that was absolutely perfectly tuned for those 2 minutes of that one DVD out of my 2500 DVDs.


----------



## AZGAMD




> Quote:
> Originally Posted by *AZGAMD* /forum/post/13223103
> 
> 
> Any ideas for a 4'wx6'l window? I don't want to cover it with framing and drywall, but don't mind putting something over it. I was thinking of an acoustic treatment and mirror another opposite it on the other wall. Any other ideas?



I was hoping someone might have an idea for my situation or is a fiberglass panel the best option? The carpet went in Saturday and now I am changing my focus onto the window and room treatments.


----------



## yngdiego




> Quote:
> Originally Posted by *AZGAMD* /forum/post/13301264
> 
> 
> I was hoping someone might have an idea for my situation or is a fiberglass panel the best option? The carpet went in Saturday and now I am changing my focus onto the window and room treatments.



Since you will see the panels from both sides (right?) you might look at the bass trap bags at Ready Acoustics. You would have to trim one bag down, but should give a professional finished appearance on both sides. I can't remember if you have to buy a whole set, or could just get two bags.


You could also cover it in GOM, paying attention to hide the seams where you won't see them from the front or back.


The panels would be lightweight, so holding them in place would not be hard.


----------



## TheTurk




> Quote:
> Originally Posted by *pepar* /forum/post/13299446
> 
> 
> I had that same comment in the reply window two times and decided against posting it.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Adding another inch to the depth might be possible. I might also load two sheets in and try to cover it with GOM so that the "proud" rockwool got rounded over into nice edges.



When I went to Home Depot, 2" looked really flimsy and 4" did not look esthetically good which would have caused a problem with the wife. I thought i could somehow push the 2" Rockwool towards the front part and keep it staple. I quickly found out after building the frames that it wasn't going be possible to keep the Rockwool in the front part as I wanted. I'll try to squeeze two of them and cover them with GOM and see what happens. Worst case I can mill them at 2".


----------



## luckybeanbean

Dear all, I have a question about fiberglass. The shop that I can find selling OC703 has them on a roll, instead of a 2' x 4' board. It feels very fluffy, like a very light blanket. It is labelling 48kg/m3. Is it the same as a rigid board type? Or they are two different things? Thanks all.


----------



## penngray




> Quote:
> Is it the same as a rigid board type? Or they are two different things? Thanks all.



Im not the expert on this but if its not compressed into a rigid board it wont have enough density for acoustics. I would say very light and fluffy is not good.


Ebay has some 2x4 OC703 recently for a good price, check it out


or


Local HVAC supplier will have something CertainTeed [ToughGard Duct Board] it has decent acoustical performance #s.


I have learned that anything with "acoustical" in the name is extremely marked up these days.

anything with "acoust


----------



## pepar




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/13317479
> 
> 
> Dear all, I have a question about fiberglass. The shop that I can find selling OC703 has them on a roll, instead of a 2' x 4' board. It feels very fluffy, like a very light blanket. It is labelling 48kg/m3. Is it the same as a rigid board type? Or they are two different things? Thanks all.



703 on a roll? Check again to see that it's 703. I'd be surprised because, I believe, the density prevents it from being rolled.


----------



## yngdiego




> Quote:
> Originally Posted by *pepar* /forum/post/13318115
> 
> 
> 703 on a roll? Check again to see that it's 703. I'd be surprised because, I believe, the density prevents it from being rolled.



Ya I can't see 703 being on a roll. I ordered a couple of bales of it, and there's no way you could roll-up 703 without causing *serious* damage to it. I would not describe 703 as a light fluffy blanket. It has density, does not easily bend and I'd certainly describe it as semi-rigid.


Sounds like the stuff you saw is the typical house insulation used in attics or wall cavities that is light and fluffy like a blanket and cannot support its own weight.


OC703 is rigid enough that you can support a 2'x4' sheet on the very ends and it won't deform.


----------



## luckybeanbean

Thanks for all your help. I am not living in US. That's why I am having a hard time finding the OC703. It is strange that the roll has the density 48kg/m3 labelled on the bag, but it feels very light with a large bundle. I will see if other shop sells the board type. Again, thanks all.


----------



## penngray




> Quote:
> Thanks for all your help. I am not living in US. That's why I am having a hard time finding the OC703. It is strange that the roll has the density 48kg/m3 labelled on the bag, but it feels very light with a large bundle. I will see if other shop sells the board type. Again, thanks all.



You can use it, you just need to compress it into a 2x4 DIY box and use chicken wire or something. I saw some pics somewhere about someone creating DIY base traps that way with regular "fluffy" insulation.


----------



## BasementBob

luckybeanbean:


Don't be obsessed with 703. Almost anything on this page will do: http://www.bobgolds.com/AbsorptionCoefficients.htm . Several will work better than 703.


----------



## luckybeanbean




> Quote:
> Originally Posted by *BasementBob* /forum/post/13323521
> 
> 
> luckybeanbean:
> 
> 
> Don't be obsessed with 703. Almost anything on this page will do: http://www.bobgolds.com/AbsorptionCoefficients.htm . Several will work better than 703.



Thanks BasementBob, I finally found a shop selling 703. But the shop owner tells me it is not recommended to use in home environment, because it is carcinogenic. True?


----------



## SRR




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/13325336
> 
> 
> Thanks BasementBob, I finally found a shop selling 703. But the shop owner tells me it is not recommended to use in home environment, because it is carcinogenic. True?



False, you put the same stuff in your walls, just the stuff in the walls is not compressed. It can be a irritation to your skin and lungs if you touch/rub/wave it around, so that the lose particles become airborne and then touch your skin/inhaled by your lungs. Needless to say the stuff won't kill ya, just use nitrate gloves those gloves that nothing can penetrate, don't rub your face in it, wear a mask if you must, and don't wave it around like a flag. Once covered with fabric, even see thru GOM, you are more then covered, or its covered, or the covering, ah...you get the gist.


BTW, when I installed my insulation (in wall) for the basement I didn't do any of that protective stuff, but then it was covered in plastic with little vents, so I really never came in contact with the stuff. But on the other hand (well both hands) I did use gloves for my rockboard 60 bass traps installs.


----------



## penngray




> Quote:
> Once covered with fabric, even see thru GOM, you are more then covered, or its covered, or the covering, ah...you get the gist.




um....the fibers will still break free and flow into the air in the room...how mcuh I dont know but I was thinking about this last night when I was testing putting GOM over the OC703 or Rockboard stuff ( I have both).


There is nothing really stopping the small mciro fibers from getting out. All I can say is Filter the rooms properly


----------



## yngdiego




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/13325336
> 
> 
> Thanks BasementBob, I finally found a shop selling 703. But the shop owner tells me it is not recommended to use in home environment, because it is carcinogenic. True?



What doesn't cause cancer these days?







Just cover it with GOM, and as others have said, wear protective gear when you are cutting it and installing. I even left the back of the my clouds and wall/ceiling pieces uncovered on the back. I have bigger fish to fry than worrying about a random fiberglass fiber working lose and making its way into my lungs.


But while I was cutting it I looked like a space alien...gloves taped to long sleeve shirt, breathing mask, tape around my collar, shoes, etc. Darn hot too..and I ended up throwing away the shirt I worked in because it was covered in little fibers.


----------



## BasementBob




> Quote:
> I finally found a shop selling 703. But the shop owner tells me it is not recommended to use in home environment, because it is carcinogenic. True?



False.


Read this thread Recording.org: Exposing the Myths of Fiberglass . Believe everything Rod Gervais says. Rod is a multi-disciplined engineer. His background in construction is wide ranging, from national museums to recording and movie studios and huge soundproof hotels. They guy literally will not use a product in a way that has not been scientifically proven in a way he and his peers approve of, and as a result his projects work as designed the first time every time. It's why we believe him. He's got a reputation par excellance as long as I've known him.


After you put up a rigid panel, or before you cover it in GoM, vacume it to remove all the little loose fibers. Reduces dust.



That said, you can always go green.

i.e. leave man made fibers and go to Cotton or Sheep Wool as an absorber material:
http://www.acousticotton.com/ 
http://www.bondedlogic.com/ 
http://www.acousticalsurfaces.com/ec..._acou_test.htm 
http://www.secondnatureuk.com/ 


Now for the part where I don't know what I'm talking about:

Watch what they use to fireproof cotton though. Yes, Boric Acid is a weak acid that is used to treat ear infections, cold sores, and vaginal yeast infections and hospitals used to use it an eye wash for children. Mix Boric Acid too dense and suddenly it's rat poison. I don't know.


----------



## luckybeanbean

thanks everyone. I will go ahead with the fiberglass. Here is the framework of my absorber and panel traps. I will link some more photos when I finished treating my place. Thanks again


----------



## pepar




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/13331309
> 
> 
> thanks everyone. I will go ahead with the fiberglass. Here is the framework of my absorber and panel traps. I will link some more photos when I finished treating my place. Thanks again



Nice start!


----------



## SPDSpappy

I'm planning on building the traps w/ OC 703 triangles from floor to ceiling in the front behind the false wall. However, I'm not sure what to do in the back. If you take a look @ my HT design ( image here ), you'll see that the left rear corner of the room is where my equipment closet is. I can probably fit the same triangle built trap on the right side rear (will depend on how the seats actually end up fitting), but not sure if I should put in the 3 corner traps (2 front, 1 rear), or just stick w/ the 2 in the front and do something different in the back. Your thoughts?


----------



## pepar




> Quote:
> Originally Posted by *SPDSpappy* /forum/post/13334512
> 
> 
> I'm planning on building the traps w/ OC 703 triangles from floor to ceiling in the front behind the false wall. However, I'm not sure what to do in the back. If you take a look @ my HT design ( image here ), you'll see that the left rear corner of the room is where my equipment closet is. I can probably fit the same triangle built trap on the right side rear (will depend on how the seats actually end up fitting), but not sure if I should put in the 3 corner traps (2 front, 1 rear), or just stick w/ the 2 in the front and do something different in the back. Your thoughts?



I am a step or two ahead of you. Search this thread for my posts w/pics re the traps behind my false wall. They made a dramatic improvement and had me thinking that I did not need to add traps in the rear. I will be taking some FR and decay measurements soon, but I *think* that I do need more traps.


----------



## penngray

anyone used R-max sheathing?.... http://www.nottatwater.com/specialty...20Plus%203.pdf 
_

R-matte plus 3 is a rigid foam plastic thermal insulation board composed of polyiscyanurate foam bonded to a durable white-matte non glare

aluminum facer and a reflective reinforced aluminum facer._


I was in lowes on the weekend and I saw these 4x8 sheets and I thought they would be great for the upper half of the walls instead of some sort of poly batten.



Anyone have an opinon on this?


----------



## nathan_h




> Quote:
> Originally Posted by *luckybeanbean* /forum/post/13331309
> 
> 
> thanks everyone. I will go ahead with the fiberglass. Here is the framework of my absorber and panel traps. I will link some more photos when I finished treating my place. Thanks again



Very cool looking.


But what are you going to do about that A/C unit? That thing has got to be so loud that the benefits of acoustic treatment are almost lost?


As I near the first summer with my dedicated room, which so far doesn't have A/C, I am struggling with a similar issue.


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13335569
> 
> 
> anyone used R-max sheathing?.... http://www.nottatwater.com/specialty...20Plus%203.pdf
> _
> 
> R-matte plus 3 is a rigid foam plastic thermal insulation board composed of polyiscyanurate foam bonded to a durable white-matte non glare
> 
> aluminum facer and a reflective reinforced aluminum facer._
> 
> 
> I was in lowes on the weekend and I saw these 4x8 sheets and I thought they would be great for the upper half of the walls instead of some sort of poly batten.
> 
> 
> 
> Anyone have an opinon on this?



I do.










Poly batting adds sound absorption at mid to upper frequencies -- though not nearly as efficiently as dense fiberglass. It is a porous absorber. Rigid foam is not, so these two materials are not equivalent.


The facts about poly batting have been long misrepresented on this forum. I was quite dumbfounded when I first came here and learned of the story going around. I can only surmise that the CEDIA acoustical powers that be (I won't mention names







) were just following a rote formula, and didn't know all the "whys" of it.


"Diffusion" was the original claim for upper wall polyester batting. I debunked that, since a homogenous absorber does not add diffusion by any known physical means. Now the story is something like "making the upper space even beneath the upper GOM." The only problem with that explanation is that you don't need anything at all behind stretch-mounted fabric. It is fully supported at its edges. And besides, as I said (and which can easily be shown in testing) polyester batting is not acoustically inert.


So unless, through *acoustical modeling or testing*, you know that you need some absorption in these physical areas, then I say save your money and don't use anything.


Regards,

Terry


----------



## penngray

Thanks Terry,


its hard to figure out what is right and wrong and since this is DIY project I really want to learn how to figure it all out on my own.


I have OC703 on the bottom half of the walls and the full front wall, with Rockwool 60 for bass traps in the corners. Why? well after reading probably 20-30 different HT threads it just seems they all do the same thing and the results are awesome to them.


This leaves the bottom 1" thicker then the top so to keep the wall at the same depth Im just looking to put something on the upper wall. It always helps to have soemthing on the upper walls so that my fabric will look good (using furring strips, etc).

So what should I use if I still want something behind it?


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13336978
> 
> 
> So what should I use if I still want something behind it?



Air is good.










If there is an issue with seeing through the fabric, a second, neutral-colored fabric used as a scrim will solve this.


Regards,

Terry


----------



## penngray




> Quote:
> Air is good.
> 
> 
> If there is an issue with seeing through the fabric, a second, neutral-colored fabric used as a scrim will solve this



Where can I buy this "Air" thing you talk about it










I will see how the fabric looks without at the top without anything behind accept drywall. I will also use 1/4" inch thick furring strips.


I have chair rail between my top section and my bottom accoustically treated section so it might be okay.


----------



## yngdiego




> Quote:
> Originally Posted by *penngray* /forum/post/13340625
> 
> 
> Where can I buy this "Air" thing you talk about it
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I will see how the fabric looks without at the top without anything behind accept drywall. I will also use 1/4" inch thick furring strips.
> 
> 
> I have chair rail between my top section and my bottom acoustically treated section so it might be okay.



Both the black and "straw" GOM provide highly opaque coverage. Both provided me 100% (and I do mean 100%) hiding of the yellow OC703 behind the fabric. So I doubt you would need two layers.


----------



## luckybeanbean




> Quote:
> Originally Posted by *nathan_h* /forum/post/13335977
> 
> 
> Very cool looking.
> 
> 
> But what are you going to do about that A/C unit? That thing has got to be so loud that the benefits of acoustic treatment are almost lost?
> 
> 
> As I near the first summer with my dedicated room, which so far doesn't have A/C, I am struggling with a similar issue.



Oh, that ac unit will be gone and the window will be block. thanks for the reminder.


----------



## nathan_h









Begs the question of how you'll control the room temp after it's gone...


----------



## penngray

anyway to acoustically treat a window without removing it?


I think my window is at a reflection point in the room.


----------



## yngdiego




> Quote:
> Originally Posted by *penngray* /forum/post/13353767
> 
> 
> anyway to acoustically treat a window without removing it?
> 
> 
> I think my window is at a reflection point in the room.



I had a similar dilemma in my HT. I ended up rotating my HT 90 degrees so the TV was in front of the window. If you don't want to look out the window, I don't see why covering it with an acoustical panel(s) wouldn't do the trick.


----------



## Ethan Winer




> Quote:
> Originally Posted by *penngray* /forum/post/13353767
> 
> 
> anyway to acoustically treat a window without removing it? I think my window is at a reflection point in the room.



Put a panel there on a stand. Or hang a panel from the ceiling. Or get a really heavy curtain and close it when listening.


--Ethan


----------



## SteveMo

I recall someone recommending not to have back-panels on my ceiling tiles after I ordered them. I have tried removing those and it causes a slight null at around 160Hz, it smooths out my response from 100Hz to 60Hz and it increases the response from 10Hz to about 25Hz. This is after removing almost a complete row of them from the sides of my room.


Should I continue to remove these?


Above my tiles there isn't much. There is a layer of pink stuff I put across the ceiling joist I put up in a few hours. Above that is steel and concrete. Two steel beams run across the room horizontally and there is gaps between those. I need insulation for the back of my room and I was considering taking all the insulation out of my ceiling and placing those in my back wall area that is not filled with insulation. Then I could fill the ceiling with something else somehow. I was thinking maybe some Roxul but I am not sure how to place it. Any advise?


----------



## SteveMo

I will go ahead and continue removing the back-panels and do some testing without them. My ceiling runners will not support the size weight of them anyway and they keep becoming loose so it is at least worth a try.


----------



## luckybeanbean

Dear all, I was going to make a panel bass trap with a 4" depth with 1/8 plywood. Planned to put 2" oc703 inside with 2" air space, but my worker has accidental stuffed 4" inside the box and sealed it. Although it can still vibrate, but minimally. It will be very painful if I need to remove all of them and do it again







How would it affect the performance? thanks


----------



## Terry Montlick

Did you really want a tuned panel absorber to begin with? The one you describe has a center frequency of about 170 Hz, with a bandwidth of only about 40 Hz. That's pretty limited absorption, unless you know you need to treat these specific frequencies.


Not much changes with the full 4" of porous interior absorber (frequency goes down a bit). I think that plywood is stiff enough not to be effected by the contact. Not so with a limp panel, like mass loaded vinyl.


Regards,

Terry


----------



## penngray




> Quote:
> Put a panel there on a stand. Or hang a panel from the ceiling. Or get a really heavy curtain and close it when listening.



how about build a nice 2" panel that fits into the window, I can remove it when I need too. The Dedicated HT room isnt so dedicated according to the wife










or I was thinking about buying sound "sound absorptions sheets" I found on ebay that I can make curtains out of....

_NRC Rating: .70

Size/Weight: Approx. 80’’x 44’’; Weight: 4.5-6 lbs; Thickness: .25"-.5" (per sheet)

Coverage Area: Approx. 195 square feet

Color: White

Made from natural acoustic cotton/wool technology

Simple to install. Hung on walls, ceilings or over windows in minutes with Megaclips

Lightweight & Durable

Environmentally friendly - No Fiberglass!!
_


----------



## luckybeanbean




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13376879
> 
> 
> Did you really want a tuned panel absorber to begin with? The one you describe has a center frequency of about 170 Hz, with a bandwidth of only about 40 Hz. That's pretty limited absorption, unless you know you need to treat these specific frequencies.
> 
> 
> Not much changes with the full 4" of porous interior absorber (frequency goes down a bit). I think that plywood is stiff enough not to be effected by the contact. Not so with a limp panel, like mass loaded vinyl.
> 
> 
> Regards,
> 
> Terry



Thanks Terry, glad to know that the panel absorber still works. The panel is actually 1/4" instead of 1/8", my mistake. My room is 12' x 18' x 8.6', so I would like more 90-100hz absorption.


----------



## penngray

Another question from the noobie section.


How wide and thick do corner bass traps have to be. Im still considering DIYing them by creating a tri-angle frame for each corner that fits 100% of the corner. I was think of having it 12"x12"x12". is that too much or not enough for bass traps. I would fill the bottom 4 feet with Rockwool 60 and the top with just poly batten.



I can only put them in 3 corners too because one corner is a door.


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13380428
> 
> 
> Another question from the noobie section.
> 
> 
> How wide and thick do corner bass traps have to be. Im still considering DIYing them by creating a tri-angle frame for each corner that fits 100% of the corner. I was think of having it 12"x12"x12". is that too much or not enough for bass traps. I would fill the bottom 4 feet with Rockwool 60 and the top with just poly batten.
> 
> 
> 
> I can only put them in 3 corners too because one corner is a door.



Why not go all the way to the top with the Rockwool? Tricorners are extra-good.


As for the size, you mean 12"x12", with the diagonal of course being greater than 12" right? (~17" according to that Pythagoras guy







)


This is a good size for the 60 kg/m^3 rockwool. If you doubled the size, this would only improve absorption below about 60 Hz, according to my back-of-the-envelope guestimate.


Regards,

Terry


----------



## yngdiego




> Quote:
> Originally Posted by *penngray* /forum/post/13380428
> 
> 
> Another question from the noobie section.
> 
> 
> How wide and thick do corner bass traps have to be. Im still considering DIYing them by creating a tri-angle frame for each corner that fits 100% of the corner. I was think of having it 12"x12"x12". is that too much or not enough for bass traps. I would fill the bottom 4 feet with Rockwool 60 and the top with just poly batten.
> 
> 
> 
> I can only put them in 3 corners too because one corner is a door.



I cut the 2x4 sheets of OC703 into eight triangles. This resulted in lengths along the walls of about 18" if memory serves me right. The hypotenuse is about 24". I agree with the other guy, why not go full height with the Rockwool?


----------



## armstrr

ok, so i started reading this thread about an hour ago, i got to page 4 or so of 104. is there a guide or manual, free or for sale that gives general directions or is this too room specific. i have already begun my home theater and don't want to screw it up (too badly). anyone have any idea what denis E's lowest design package goes for? i already have my room dimentions, chairs picked projector picked etc. i think i'll do ok for the most part, but the room acoustics are going to give me headaches...i'ld rather build the room than read till my eyes bleed. My preference would be not to use furring strips. i can handle installing panels both as an asthetic and acoustic treatment once the room is built. any thoughts on a consolodated resource. perhaps i'll pm this to denis...


----------



## SRR




> Quote:
> Originally Posted by *armstrr* /forum/post/13383631
> 
> 
> ok, so i started reading this thread about an hour ago, i got to page 4 or so of 104. is there a guide or manual, free or for sale that gives general directions or is this too room specific. i have already begun my home theater and don't want to screw it up (too badly). anyone have any idea what denis E's lowest design package goes for? i already have my room dimentions, chairs picked projector picked etc. i think i'll do ok for the most part, but the room acoustics are going to give me headaches...i'ld rather build the room than read till my eyes bleed. My preference would be not to use furring strips. i can handle installing panels both as an asthetic and acoustic treatment once the room is built. any thoughts on a consolodated resource. perhaps i'll pm this to denis...


 http://www.realtraps.com/articles.htm


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13353767
> 
> 
> anyway to acoustically treat a window without removing it?
> 
> 
> I think my window is at a reflection point in the room.



You can make a fabric-covered "plug" for it out of rigid fiberglass which fits tightly into the window recess. This will also block the light from the window.


Make two of them, and hang the other one on the opposite side wall for perfect symmetry!


Regards,

Terry


----------



## BasementBob

Terry Montlick:

I concur with your signature.


----------



## yngdiego




> Quote:
> Originally Posted by *BasementBob* /forum/post/13386710
> 
> 
> Terry Montlick:
> 
> I concur with your signature.



Wow..had no idea..that's terrible the site had to be taken down!


----------



## SteveMo




> Quote:
> Originally Posted by *SteveMo* /forum/post/13354712
> 
> 
> I recall someone recommending not to have back-panels on my ceiling tiles after I ordered them. I have tried removing those and it causes a slight null at around 160Hz, it smooths out my response from 100Hz to 60Hz and it increases the response from 10Hz to about 25Hz. This is after removing almost a complete row of them from the sides of my room.



It seems to me that it is a problem with my back wall...


----------



## eugovector




> Quote:
> Originally Posted by *pepar* /forum/post/13393415
> 
> 
> Indeed. That is an outrage. Is the subject forum accepting donations for their defense fund?



I vote we take all this to another thread. I'll leave it to someone else to start it. I know this main thread is already plenty long, and we don't want to turn off anyone on the fence about acoustic treatment.


----------



## penngray




> Quote:
> Why not go all the way to the top with the Rockwool? Tricorners are extra-good.



Pure cost question.


I have to buy more Rockwool, I was wondering if there is a "diminished returns" effect after I have so much already, more likely I dont have enough yet and there is probably a "diminished returns" effect or "Deading" of the room if I go too far.



bw, yes it wasnt 12x12x12 I had a typo, its 12x12x17 sorry about that.


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13394492
> 
> 
> Pure cost question.
> 
> 
> I have to buy more Rockwool, I was wondering if there is a "diminished returns" effect after I have so much already, more likely I dont have enough yet and there is probably a "diminished returns" effect or "Deading" of the room if I go too far.
> 
> 
> 
> bw, yes it wasnt 12x12x12 I had a typo, its 12x12x17 sorry about that.



Since the greatest benefit for any acoustical treatment is always at the beginning, you could put a "diminishing returns" point anywhere! But to absorb bass in the above-subwoofer range (>80 Hz), all the corners are useful. And it is hard to "overdeaden" a room with just corner treatment. The lower down below around 80 Hz, the more aggressive and extensive the treatment has to be, simply because it becomes less effective.


Regards,

Terry


----------



## NautussutuaN

Need some direction on ideas for front wall treatment.. I know there is tons of stuff mentioned in this thread and have kinda skimmed but want to ask outright with the hopes of a simple answer or a link to what I need to know..

Front wall is about 13' 1/2" drywall and 8' (drop ceiling).. I was hoping to get some kind of curtain or fabric to hang on the front wall from a local JoAnn Fabrics or similar.. can anyone provide a name of a material i should look for at a store like this just to cover the front wall in hopes to help with the acoustics..


----------



## Terry Montlick




> Quote:
> Originally Posted by *NautussutuaN* /forum/post/13394786
> 
> 
> Need some direction on ideas for front wall treatment.. I know there is tons of stuff mentioned in this thread and have kinda skimmed but want to ask outright with the hopes of a simple answer or a link to what I need to know..
> 
> Front wall is about 13' 1/2" drywall and 8' (drop ceiling).. I was hoping to get some kind of curtain or fabric to hang on the front wall from a local JoAnn Fabrics or similar.. can anyone provide a name of a material i should look for at a store like this just to cover the front wall in hopes to help with the acoustics..



No fabric at JoAnns will really help with acoustics. It is too thin to do much of anything. Such fabric can, however, be used to *hide* acoustic treatments, such as fiberglass.


Regards,

Terry


----------



## xp800

I'm planning for the acoustic treatments in my HT room. I will be doing what seems to be the recommended approach: front wall and first 2' of side walls fully covered in OC/Linacoustic and then lower half of side walls treated. I have some questions regarding these materials however.


I will not be making standalone panels. I will be furring out the depth of the product I choose and covering with GOM. So I'll be doing the absorbing 'wall' approach.


Is there a reason to prefer the rigid boards over the rolled product? It seems like the rolls of Linacoustic are significantly cheaper per square foot, but with slightly lower NRCs.


Which leads me to my next question. Is there a reason to prefer the OC703 over the Linacoustic R300? The reason I ask is that most people refer to the OC703 when building panels. Is this simply because they come in 2'x4' sheets rather than 4'x8' R300? I have a lot of surface to cover, so the larger boards are appealing. I just don't see the R300 mentioned as much.


When I look at the NRCs for both rigid products, they appear mostly identical. And the Linacoustic is black with a surface treatment that may make it easier to handle (?). I also think that the 1.5" thick Linacoustic would be friendlier for the furring I'd be doing.


Now for costs. I have an idea what the OC703 and RC products go for, but what have people paid for the R300?


Any input would be helpful.


Thanks!


----------



## Terry Montlick

The acoustical differences between these fiberglasses is so small as to be insignificant for the majority of cases. The rolls of Linacoustic have somewhat lower density, and the facing makes them a bit easier to manage and perhaps not quite as irritating to the skin.


Go with whatever you can get a good price on and install the easiest.


Regards,

Terry


----------



## penngray




> Quote:
> Is there a reason to prefer the OC703 over the Linacoustic R300?




I think its all about price. Anything with "acoustic" in it for some reason is 3x the price, marketing at its best kind of like "Monster"







My local supply company found it shocking that the R300 was extremely over priced compared to TG EI800 or TG EI475, which are similar duct boards.


OC703 isnt even the best price stuff..Rockboard60 is thicker and cheaper.


----------



## penngray

question about using rigid styrofoam.


I have 12 sheets of 2x4 OC703 that Im going to be placing around my walls below ear level in my HT room. Most is going to be front wall and side walls but I will have some on the back wall too.


I will have gaps in my wall and I dont want to frame around the 2x4 sheets, instead I want to fill the gaps. I know poly batting will work but what about rigid styrofoam 1" thick. I see 4'x8' sheets at HD all the time for $10 or so can I use this as a "filler" between the OC703?


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13399341
> 
> 
> question about using rigid styrofoam.
> 
> 
> I have 12 sheets of 2x4 OC703 that Im going to be placing around my walls below ear level in my HT room. Most is going to be front wall and side walls but I will have some on the back wall too.
> 
> 
> I will have gaps in my wall and I dont want to frame around the 2x4 sheets, instead I want to fill the gaps. I know poly batting will work but what about rigid styrofoam 1" thick. I see 4'x8' sheets at HD all the time for $10 or so can I use this as a "filler" between the OC703?



Rigid styrofoam isn't an acoustic absorber. It will fill space -- that's about it.


Poly batting is a reasonable effective absorber, depending on density. Dense (semi-rigid to rigid) fiberglass is an extremely effective absorber.


Regards,

Terry


----------



## xp800




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13398185
> 
> 
> The acoustical differences between these fiberglasses is so small as to be insignificant for the majority of cases. The rolls of Linacoustic have somewhat lower density, and the facing makes them a bit easier to manage and perhaps not quite as irritating to the skin.
> 
> 
> Go with whatever you can get a good price on and install the easiest.
> 
> 
> Regards,
> 
> Terry





> Quote:
> Originally Posted by *penngray* /forum/post/13399247
> 
> 
> I think its all about price. Anything with "acoustic" in it for some reason is 3x the price, marketing at its best kind of like "Monster"
> 
> 
> 
> 
> 
> 
> 
> My local supply company found it shocking that the R300 was extremely over priced compared to TG EI800 or TG EI475, which are similar duct boards.
> 
> 
> OC703 isnt even the best price stuff..Rockboard60 is thicker and cheaper.




Thanks to you both for the replies. This is pretty much what I figured.


What company makes 'TG EI800 or TG EI475'. I Googled it and found Knauf Elcipse Duct Board. Is this correct?


----------



## nathan_h




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13394825
> 
> 
> No fabric at JoAnns will really help with acoustics. It is too thin to do much of anything. Such fabric can, however, be used to *hide* acoustic treatments, such as fiberglass.
> 
> 
> Regards,
> 
> Terry



What about using very thick blackout-style (ie, reflective at high frequencies) pleated curtains for diffusion? Not really useful, either? (I'm guessing not.)


----------



## BasementBob

Studiotips is back on line.


----------



## Terry Montlick




> Quote:
> Originally Posted by *nathan_h* /forum/post/13400983
> 
> 
> What about using very thick blackout-style (ie, reflective at high frequencies) pleated curtains for diffusion? Not really useful, either? (I'm guessing not.)



Depends on the material. Thick velour (18-32 ounce, the kind used for heavy stage curtains) has decent absorption, especially when draped loosely with lots of folds to 1/2 width. But in general, thin fabrics will not absorb, but simply allow sound to pass through and bounce right back out.










Regards,

Terry


----------



## penngray




> Quote:
> Rigid styrofoam isn't an acoustic absorber. It will fill space -- that's about it.
> 
> 
> Poly batting is a reasonable effective absorber, depending on density. Dense (semi-rigid to rigid) fiberglass is an extremely effective absorber.
> 
> 
> Regards,
> 
> Terry



As always thanks Terry!!


I wasnt really worried about acoustic absorption. I just wanted a "filler" so that my bottom half of the wall is an uniform 1" all the way around. I do believe I have enough 1" OC703 and I can just fill the spaces left over with the 1" styrofoam.


----------



## penngray




> Quote:
> What company makes 'TG EI800 or TG EI475'. I Googled it and found Knauf Elcipse Duct Board. Is this correct?



From my printed out quote I think its CertainTeed ToughGard Duct Board.


I do believe its this

http://www.certainteed.com/NR/rdonly...ardSpecSht.pdf 


The 2" EI800 stuff is what we want....NRC of .95


2x48x120" [email protected] (4 sheets) around $190, which i think its great because that is about 20 24x48 sheets. 20 OC703 sheets are over $200.


----------



## xp800




> Quote:
> Originally Posted by *penngray* /forum/post/13401789
> 
> 
> From my printed out quote I think its CertainTeed ToughGard Duct Board.
> 
> 
> I do believe its this
> 
> http://www.certainteed.com/NR/rdonly...ardSpecSht.pdf
> 
> 
> The 2" EI800 stuff is what we want....NRC of .95
> 
> 
> 2x48x120" [email protected] (4 sheets) around $190, which i think its great because that is about 20 24x48 sheets. 20 OC703 sheets are over $200.




I will certainly try to find a Certainteed dealer locally. I found one for this product with the same name.

http://www.knaufusa.com/products/bui...board-agm.aspx 


I'm finding most of these manufacturers have quite similar products the more I look into it...


Then I found this:

http://www.knaufusa.com/products/bui...cal_board.aspx 


Again looks like splitting hairs at NRCs with 2" thick 3pcf boards whether Certainteeed, OC, JM, or now Knauff. I think the challenge is finding a local distributor who even knows what we're talking about when you call and want 'duct liner' and is willing to order it. Especially problematic with the large form factor boards (which I'd prefer) and thicknesses OTHER than 1" or 2" (I'd like 1.5").


I called McCormick Insulation out in Maryland (I'm in MI) based on a post here somewhere for Linacoustic RC. The guy actually knew exactly what I was talking about and offered some alternatives. I'm hoping to hear back from him tomorrow.


----------



## pepar




> Quote:
> Originally Posted by *xp800* /forum/post/0
> 
> 
> I called McCormick Insulation out in Maryland (I'm in MI) based on a post here somewhere for Linacoustic RC. The guy actually knew exactly what I was talking about and offered some alternatives. I'm hoping to hear back from him tomorrow.



They have locations all over the U.S.

http://www.spi-co.com/


----------



## distoga

I've only had luck finding JM (John Manville) IS 300 and IS 600 locally. It also comes in 4'x8' sheets which actually works out better for me since it's mainly to treat the front and rear (if needed) walls.


The specs are:


IS 300 2" (51mm) 3pcf (48kg/m3) 0.24 1.00 1.11 1.08 1.06 1.05 1.05

IS 600 2" (51mm) 6pcf (96kg/m3) 0.38 0.93 1.10 1.07 1.07 1.07 1.05


I've searched the forum with the built in search tool and google but neither can find references to the IS 600. Is the IS 600 a match to the 705 FRK or just 705? Is the IS 600 ideal for bass traps?


My thought is putting is 300 on the entire front wall and then making triangle/chunk bass traps with the is 600 in the front corners.


A minor twist is in my HT I'll have about 40 linear feet of the 70' perimeter covered in a thick theater like fabric which will remove mostly highs, maybe too much... This is why I wonder if the front wall should be the IS 600 so I don't remove too much high?


All surfaces, even the ceiling, in the room are cement, no framing, studs, or sheetrock behind the curtains, columns or AT screen.


----------



## CrashX

Anyone use Johns Manville 475 Duct Board (rigid)? A company my dad works with can get some for a good price. It comes in 4'x10' sheets, 1 in thick. I did find it on jm.com and it has what appears to be good acoustic properties, but then again, I am not an expert in reading it. It has a foil backing, but it could be pulled off it it's a bad thing to have.


Anyone have any experience or opinions on such a product. Is it all the same? Should the foil be pulled off?


----------



## CrashX

Well, I found a PDF on JM's site and it appears to have acoustic properties of everything else:


Thickness Frequency (Hz)

Type (inches) (mm) 125 250 500 1000 2000 4000 NRC

475 1 25 .07 .25 .63 .90 .97 1.00 .70


So it looks fine and just another variation of the same.


----------



## penngray




> Quote:
> It has a foil backing, but it could be pulled off it it's a bad thing to have.



I have read that the foil would reflect the sound, you need to probably pull it off. Of course a true expert here will confirm that at some point.


----------



## CrashX

I also read that if the foil is against the drywall it's no different than the drywall itself reflecting the sound. Plus it would be reflected after being absorbed by the panel, so the amount reflect would be greatly reduced, if not absorbed again going back through the panel. But, I am no expert either


----------



## penngray




> Quote:
> I also read that if the foil is against the drywall it's no different than the drywall itself reflecting the sound.



yes, if its against the wall I believe you are okay....doh! I didnt think of that. Its late


----------



## SRR




> Quote:
> Originally Posted by *distoga*  /forum/post/13418613
> 
> 
> I've only had luck finding JM (John Manville) IS 300 and IS 600 locally. It also comes in 4'x8' sheets which actually works out better for me since it's mainly to treat the front and rear (if needed) walls.
> 
> 
> The specs are:
> 
> 
> IS 300 2" (51mm) 3pcf (48kg/m3) 0.24 1.00 1.11 1.08 1.06 1.05 1.05
> 
> IS 600 2" (51mm) 6pcf (96kg/m3) 0.38 0.93 1.10 1.07 1.07 1.07 1.05
> 
> 
> I've searched the forum with the built in search tool and google but neither can find references to the IS 600. Is the IS 600 a match to the 705 FRK or just 705? Is the IS 600 ideal for bass traps?
> 
> 
> My thought is putting is 300 on the entire front wall and then making triangle/chunk bass traps with the is 600 in the front corners.
> 
> 
> A minor twist is in my HT I'll have about 40 linear feet of the 70' perimeter covered in a thick theater like fabric which will remove mostly highs, maybe too much... This is why I wonder if the front wall should be the IS 600 so I don't remove too much high?
> 
> 
> All surfaces, even the ceiling, in the room are cement, no framing, studs, or sheetrock behind the curtains, columns or AT screen.



Rockboard 60 might be better for down low bass trapping.

http://www.atsacoustics.com/item--Ro...f-6--RB60.html 

http://www.roxul.com/graphics/RX-NA/...d60-8-7-07.pdf 


EDIT: I was looking wrong (wasn't comparing the same thicknesses), the 600 stuff looks great. But what does it cost?


----------



## c-not-k

I've done a search, but this thread is pretty long, so I apologize in advance if my answer is in here somewhere.


Anyway, I want to treat the corners of my theater, but I'm limited in trap size by aesthetics. I want to put two vertical corner traps on the screen wall. A pleasing size would be ~10"x10"x14" (triangle) by ~5' tall.


On the rear wall (wall/ceiling junction) it would be ~11"x11"x16" by ~ 15' wide.

 


My question is how effective will traps of this size be? Is something this size better than nothing?


IIRC, a traps lowest effective frequency is based on the biggest quarter-wavelength that will fit (ignoring the effect of the absorption material. I was going to use OC 703.) This would be easy to calculate this for a rectangular trap. How would you calculate that for a triangular one?


Thanks


----------



## Terry Montlick




> Quote:
> Originally Posted by *c-not-k* /forum/post/13439082
> 
> 
> ...
> 
> IIRC, a traps lowest effective frequency is based on the biggest quarter-wavelength that will fit (ignoring the effect of the absorption material. I was going to use OC 703.) This would be easy to calculate this for a rectangular trap. How would you calculate that for a triangular one?



For a really big flat absorber, a quarter wavelength is the depth at which you typically get close to maximum absorption. But you get some piece of lower frequencies, since absorption in not an all-or-nothing proposition.


And there is a more important thing in acoustics called the "edge effect." This happens when waves are roughly comparable in size to the absorber. The waves bend in toward the surface, so that the effective absorption area is larger. This is a wave diffraction phenomenon, and I don't have a good "cartoon physics" way of portraying it!










But the end result is good. You get additional low frequency absorption which is related to the width of your corner absorber, not just its depth. I don't know of anything like an accurate formula for it, though.


Regards,

Terry


----------



## distoga




> Quote:
> Originally Posted by *SRR* /forum/post/13424582
> 
> 
> Rockboard 60 might be better for down low bass trapping.
> 
> 
> EDIT: I was looking wrong (wasn't comparing the same thicknesses), the 600 stuff looks great. But what does it cost?



It's $.13 more a sqft than 300. The 300 price though seemed a little high.


----------



## bpape




> Quote:
> Originally Posted by *c-not-k* /forum/post/13439082
> 
> 
> I've done a search, but this thread is pretty long, so I apologize in advance if my answer is in here somewhere.
> 
> 
> Anyway, I want to treat the corners of my theater, but I'm limited in trap size by aesthetics. I want to put two vertical corner traps on the screen wall. A pleasing size would be ~10"x10"x14" (triangle) by ~5' tall.
> 
> 
> On the rear wall (wall/ceiling junction) it would be ~11"x11"x16" by ~ 15' wide.
> 
> 
> 
> 
> My question is how effective will traps of this size be? Is something this size better than nothing?
> 
> 
> IIRC, a traps lowest effective frequency is based on the biggest quarter-wavelength that will fit (ignoring the effect of the absorption material. I was going to use OC 703.) This would be easy to calculate this for a rectangular trap. How would you calculate that for a triangular one?
> 
> 
> Thanks



It's not that the 1/4 wave is as low as it will absorb anything, it's that it's where it's most effective. Smaller absorbers will still reach down into lower frequencies, just not with a large coefficient per unit area.


Absorbers the size you're specifying will still do some good down into the subwoofer range and are certainly better than nothing.


Bryan


----------



## penngray

Anyone have any knowledge or links on the acoustical numbers of carpet pad?


I have lots left over still and I was actually thinking of using it on the top half of the walls if it doesnt have much absorption. I have decided that I do want something under my fabric on the top half of the walls still (atleast today I have decided that....flip/flop....flip/flop )


----------



## NautussutuaN

After extensively searching, questioning and reading... I have found a local HVAC dealer that sells OC703 but for $111.00 a case (72 sqft) I am debating on going with a product called Fibrex ( http://www.fibrexinsulations.com/pro...ial_board.html )

which is a hell of a lot cheaper and since I didn't take into account acousitcs when builing my theater (dumb mistake) I don't want to go over board on expensive techniques that might not be much better than the corner trap I am building using this Fibrex.. Does anyone know anything about it and would say for the difference in price which is at $40.00/case (64 sqft) it would be good to use.


----------



## bpape

That's just a brand of mineral wool. It will work fine - though it's nasty to work with compared to 703. Use the 1240 for reflection duties and 1280 for bass absorbers unless you're doing chunk style solid ones, then the 1240 will be fine.


Bryan


----------



## NautussutuaN




> Quote:
> Originally Posted by *bpape* /forum/post/13479281
> 
> 
> That's just a brand of mineral wool. It will work fine - though it's nasty to work with compared to 703. Use the 1240 for reflection duties and 1280 for bass absorbers unless you're doing chunk style solid ones, then the 1240 will be fine.
> 
> 
> Bryan



I'm planning on the corner chunk type trap... but if i try to get this in triangle cuts and wrap with GOM or Speaker cloth what could i use to keep the front of the trap flat and some what decent looking.. I have read that someone used an FRK(?) panel in the front of the trap for a flat surface... where do I find a FRK panel? or what else could be used that would not affect the purpose of the trap itself?


----------



## Vidmaven

OK I just got some reasonably priced 2' x 4' x 6" rigid fiberglass bass traps and placed them in all 4 corners of my HT. The problem I have is that they are directly in line with the backside of my Def Tech bipole towers and are definitely absorbing the highs. My question is can I put something on the face of the trap to reflect the highs or would I be better off opening them up and putting some FRK on the inside of the face? I guess I really don't want to mess with the fiberglass if I don't have to.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Vidmaven* /forum/post/13480760
> 
> 
> My question is can I put something on the face of the trap to reflect the highs or would I be better off opening them up and putting some FRK on the inside of the face? I guess I really don't want to mess with the fiberglass if I don't have to.



You can use ordinary, inexpensive Kraft paper over the fiberglass, then cover it back up with fabric. Be sure to comply with all local building codes, as the Kraft paper (as well as FRK - Foil Reinforced Kraft paper) is not flame retardant or noncombustible.


Regards,

Terry


----------



## nosdude

Anybody with information on where I can purchase OC703 in the Dallas / Plano, TX area.


Thanks


----------



## pepar




> Quote:
> Originally Posted by *nosdude* /forum/post/13514111
> 
> 
> Anybody with information on where I can purchase OC703 in the Dallas / Plano, TX area.
> 
> 
> Thanks


 http://www.spi-co.com/servicecenterdirectory.cfm


----------



## allredp

Hey,


WAF is too low on my plans to have 48" Linacoustic from floor to chair rail, so I'm wondering if I could reverse it and have plain wall from floor up to 34-36" and then take the Linacoustic up to the ceiling? This is a multi-use family/media room, so she's got some aesthetic sensitivities I need to work with...


Would that work for broadband bass absorption, but not "kill" the room with too much absorption? Here's a pic of my friend's room--he's the carpenter I'm having do my room. Attachment 106237 In my case, I would have the Linacoustic inside taller upper boxes, while just having paint or wainscotting (sp) below.


My ceiling is not treated, nor with WAF can it be.


I have carpet on the floor, but one back corner is an 8' wide diagonal wall with fireplace and tile surround (i.e. live acoustically). Attachment 106236 


I also have a window on my far right side and several doors in the room (one double french glass door, and two 36" door to storage areas). Attachment 106234 . Otherwise the whole room would be treated from 36" off the floor to my 8' ceiling (- my crown moulding height).


My room is 15'W x 27'D.


Here's another shot to get a feel for the room--I'm going to build a stage front with columns to house my Dali Mentor 6s and build-in my Mentor Vokal center for behind my screen.


I also plan to cover the front wall with 2" of Linacoustic behind my SmX Cineweave 120" diag screen.


So, will my inverted boxes (filled with 1" Linacoustic) be workable?


Thanks for the help!

Phil


----------



## nathan_h

Someone may have a better set of answers for you but here is my impression:



> Quote:
> Originally Posted by *allredp* /forum/post/13516802
> 
> 
> WAF is too low on my plans to have 48" Linacoustic from floor to chair rail, so I'm wondering if I could reverse it and have plain wall from floor up to 34-36" and then take the Linacoustic up to the ceiling?



Short answer is "No." Long answer is that the Linacoustic is for higher frequency absorption, and you want that at likely first reflection points (like your original plan to have it UNDER the chair rail). You COULD get by with not putting it everywhere, but just at the key first reflection points, found via the mirror method:

http://www.avsforum.com/avs-vb/showthread.php?t=868585 



> Quote:
> Would that [putting it above ear height throughout the room] work for broadband bass absorption, but not "kill" the room with too much absorption?



From what I have experienced, not so much. One or two inch thick linacoustic on the walls doesn't do much for bass trapping. You'll do better with something thicker, filling a corner.


---


There are some nice looking ways to do acoustic treatment. Lots of great photos in this thread and many construction threads.


----------



## allredp




> Quote:
> Originally Posted by *bpape* /forum/post/2274805
> 
> 
> Some do, some don't. The idea is to cover a certain percentage of the wall with more absorbtion. If you go higher on shorter walls, you are actually increasing the percentage of the wall that is covered.
> 
> 
> I don't know any general rule of thumb about this. Dennis could probably provide a more experienced answer for this type of implementation.



While plowing through this amazing thread, I'm wondering if a "general rule" surfaced that will help me with my WAF problem!


I can either go up to 38" (including top trim--either chair or ledge molding) with Linacoustic, or above that height to the ceiling. Either way, I can only get away with a wall that has cloth for 1/3 or 2/3 with the other being painted or other hard-surfaced.


Any help much appreciated!

Phil


If


----------



## allredp




nathan_h said:


> Someone may have a better set of answers for you but here is my impression:
> 
> 
> 
> 
> Short answer is "No." Long answer is that the Linacoustic is for higher frequency absorption, and you want that at likely first reflection points (like your original plan to have it UNDER the chair rail). You COULD get by with not putting it everywhere, but just at the key first reflection points, found via the mirror method:
> 
> http://www.avsforum.com/avs-vb/showthread.php?t=868585
> 
> 
> 
> 
> From what I have experienced, not so much. One or two inch thick linacoustic on the walls doesn't do much for bass trapping. You'll do better with something thicker, filling a corner.
> 
> 
> nathan_h said:
> 
> 
> 
> Thanks for the insight Nathan.
> 
> 
> So, keeping my original idea of having 1" linacoustic all the way around the room up to 38" would still work?
> 
> 
> However, what exactly is it doing for me? What frequencies is it helping me with?
> 
> 
> Thanks,
> 
> Phil
Click to expand...


----------



## penngray

allredp, Im not an expert but Im applying OC703 around most of my room like you.



I have 24 2x4 sheets of OC703 that I will place about 40" high around my room, side and back walls. In the corners Im building thicker bass traps (triangle corner traps) with Rockwool 60. My front wall will have be covered top to bottom with OC703..


I dont have reflection coverage on my cieling yet either







still figuring that one out.



I still dont have enough OC703 and Im Still sourcing out cheaper alternatives. I think I have some certaboard duct liner (1 /12 " 4x10 sheets) 4 sheets for around $200 locally. Thats $1.19 per sq ft.


ebay has 4 cases of 12 OC703 1" stuff for around 125 shipped...thats about $1.30 per sq ft.



The OC703 will absorb the higher frequences 250 and up.....so you need thick corner stuff to absorb your bass frequences.


----------



## nathan_h




> Quote:
> Originally Posted by *allredp* /forum/post/13517919
> 
> 
> 
> So, keeping my original idea of having 1" linacoustic all the way around the room up to 38" would still work?
> 
> 
> However, what exactly is it doing for me? What frequencies is it helping me with?
> 
> 
> Thanks,
> 
> Phil



Yep, putting the treatment at ear level (especially at the angle of incidence that the mirror method indicates) is the right thing to do.


Frequencies:

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Jay0001

Hi all, quick qestion regarding a panel build. I searched this thread with no luck. In some builds, I've see that people have painted wooden frames to keep any light coloured wood from showing through the material used to cover the panel. (black speaker cloth for me)

What about the insulation? The 703 I have is yellow. Will I need to use two layers of speaker cloth?


Thanks for any advice.


Jay


----------



## yngdiego




> Quote:
> Originally Posted by *Jay0001* /forum/post/13521292
> 
> 
> Hi all, quick qestion regarding a panel build. I searched this thread with no luck. In some builds, I've see that people have painted wooden frames to keep any light coloured wood from showing through the material used to cover the panel. (black speaker cloth for me)
> 
> What about the insulation? The 703 I have is yellow. Will I need to use two layers of speaker cloth?
> 
> 
> Thanks for any advice.
> 
> 
> Jay



I used GOM cloth to cover my OC703 and one layer provides 100% coverage. Not sure about regular speaker cloth..


----------



## Jay0001




> Quote:
> Originally Posted by *yngdiego* /forum/post/13521321
> 
> 
> I used GOM cloth to cover my OC703 and one layer provides 100% coverage. Not sure about regular speaker cloth..



Thanks, I have a feeling that GOM is a bit "thicker" than speaker cloth. Oh well, time will tell!


Thanks,

Jay


----------



## PAP

I haven't been in this thread for a LONG time, but just happened back in.


1" linocoustic up to 38" is fine so long as your ears are less than that when listening.


The linocoustic is NOT designed for bass trapping and it will do very little of that. It's for mid and high frequency reflection and the associated flutter echo and other delay induced acoustical problems that come along with that. Accordingly you want it at any reflection point from the speakers to your ears.


There are several calculations that show that linocoustic from floor to ceiling generally will create a room that is too dead.


In my room I've got it up whatever the roll height was - 4 feet I think. And batting above that. All covered up with fabric. Typical Dennis Erskine type design from 3-4 years back. Then I've got a large amount of bass trapping behind my perforated screen.


Has your wife seen the fabric? Personally I think the fabric covered wall is much more attractive than paint, but to each his own. My room is black and dark grey all around including ceiling - totally designed for optimal viewing. Wife loves it, but it's only for movies, we don't use it for anything else. She was a skeptic, until she watched a movie and was amazed how everything but the movie screen just melted away.


cheers.


----------



## CruelInventions




> Quote:
> Originally Posted by *PAP* /forum/post/13523354
> 
> 
> Has your wife seen the fabric? Personally I think the fabric covered wall is much more attractive than paint, but to each his own. .



Depending upon the fabric, of course, a fabric covered wall can look quite attractive and classy. This is based upon a dealer showroom example I've seen using a GOM Anchorage fabric with has a subtle texture to it. Looked elegant, with the added benefit of disguising all the wall treatments hidden behind it.


In other words, I agree.


----------



## allredp




> Quote:
> Originally Posted by *PAP* /forum/post/13523354
> 
> 
> 1" linocoustic up to 38" is fine so long as your ears are less than that when listening.
> 
> 
> The linocoustic is NOT designed for bass trapping and it will do very little of that. It's for mid and high frequency reflection and the associated flutter echo and other delay induced acoustical problems that come along with that. Accordingly you want it at any reflection point from the speakers to your ears.
> 
> 
> There are several calculations that show that linocoustic from floor to ceiling generally will create a room that is too dead.
> 
> 
> ...Then I've got a large amount of bass trapping behind my perforated screen..



Awesome help!


So, I'll keep with the WAF plan and make my 1" linacoustic-filled "boxes" around the whole room up to 38" high.


I'll also try to figure out some side and rear wall treatments that will help with first reflection points.


I'm also going to "kill" my front wall with 2" linacoustic behind my AT screen (SmX CineWeave) and on/in my columns on either side of the screen that house my Dali Mentor 6's.


Bryan Pape of GIK also suggested that I do a chunked triangular floor/wall bass trap all along my back wall behind my sofa/sectional.


Cool--thanks for all the help!


I'm within days of starting the build-out...


----------



## penngray




> Quote:
> This is based upon a dealer showroom example I've seen using a GOM Anchorage fabric with has a subtle texture to it. Looked elegant, with the added benefit of disguising all the wall treatments hidden behind it.



I really like the Onyx anchorage fabric!! Its very WAF too! Buts its $17/yd, YIKES!!!!


Im going to Jo-Anns this weekend (if I can find a 50% coupon somewhere).


----------



## dbbarron

If treating a room, what treatments does one attack first?


I.e., once measurements are taken, I would assume bass traps are added first as they could influence the RT60 numbers at higher frequencies. Then re-measure and address first reflection points. Then re-measure and correct RT60 for high frequencies. Am I correct?


db


----------



## pepar




> Quote:
> Originally Posted by *dbbarron* /forum/post/13529253
> 
> 
> If treating a room, what treatments does one attack first?
> 
> 
> I.e., once measurements are taken, I would assume bass traps are added first as they could influence the RT60 numbers at higher frequencies. Then re-measure and address first reflection points. Then re-measure and correct RT60 for high frequencies. Am I correct?
> 
> 
> db



I think most of us do the general treatments, i.e. thin, first and add traps later. Whether or not that's "by the book" will need to be addressed by the pros on this thread. I will add that the amount of mid- and high-frequency absorption added by corner bass traps is usually relatively minimal.


----------



## dbbarron

A 'protocol' question:


If I am to take various measurements and post for comment as I go through the process, should it be to this thread or my construction thread (Mayflower) or to yet another thread (e.g., Mayflower Acoustics)?


db


----------



## eugovector

My opinion, this thread is plenty long, so a few more posts won't hurt. I say, try to keep it to the meat and potatoes, but post it here.


----------



## brianhutchins

I'm is the design processes of my home theater and have started to look at how I'm going to handle the acoustics. The room is 13'4" by 20' by 9' with a tray ceiling. I'm planing on doing bass traps in the front 2 corners useing 703 or whatever and either 703 or linacoustic on the front wall except behind the screen. I'll do something for the first reflection points as well. My question comes to the rear of the theater. Other then a bar top and pilars where my speakers will be housed, it will be open to my large pool table, bar, card table room. How is this normaly handled, or is it. I'm kind of hopeing that the treatments I mentioned would be enough to allow my room to sound pretty good. I know having an open rear wall is not ideal but it's what I would perfer, as I have alot of people over for fights and big games.


Thanks


Brian


----------



## Anthony1

First, I want to apologize for not reading this thread from beginning to end, or even reading the last 10 pages. After posting this, I'll try to read as much as possible, but was just hoping to throw a couple of quick questions out there, regarding first reflection points.



1. When we are talking about first relection points, are we pretty much talking about the tweeter? What I mean is, if we are using a laser pointer or flashlight with a mirror, and bouncing that off a wall to the speaker, do we want the laser pointer light, or center of the flashlight beam to hit the tweeter, and thus that would be the "eye of the storm" so to speak in terms of the first reflection for that particular speaker?


2. If say, my "eye of the storm" for my left main is around 36 inches up at a particular spot on the wall. How much area around that precise point is also reflecting the sound? What I'm getting at with this question, is what kind of circumference around the "eye of the storm" is reflecting sound? Like 2 feet in every direction, 3 feet in every direction, etc, etc...


3. Continuing from question 2, if my linacoustic is 47 inches up, and the first relection point is 36 or so inches, do I need to be at all concerned with reflections above the 47 inches of linacoustic? Because I could treat just that small portion of the wall (above the furring strip at the 49 inch mark) alot higher, even all the way to the ceiling, but I don't know if that's necessary, or actually overkill. I know that you don't want to cover all your walls from floor to ceiling in linacoustic, cause it will totally deaden the room, but at the spot of first relection, do you actually want to go floor to ceiling in that particular spot? At alot of specialty home theater stores, they typically have oc703 panels wrapped in GOM, and they have them a foot or so off the ground, and they extend well past ear level.


4. Does linacoustic help any at all towards traping bass? What I mean by this, is that in my front corners, I have oc703 superchunks, but I was thinking on the side walls, close to where the superchunks are, I might as well go floor to ceiling with the linacoustic (just close to the corners), just to help out a little bit more with traping bass, but I guess if linacoustic doesn't help whatsoever in that regard it would be a total waste?


5. Regarding the side surrounds, should linacoustic be behind the side surrounds? How large a circumference behind the side surrounds?


Again, I'm sure that all these questions I'm asking right now have been answered somewhere in this thread, maybe even within the last 10 pages or so, and I'm going to begin reading the thread, but I'm going to be putting up the fabric this weekend, and I want to make sure I make any last minute adjustments before the fabric goes up. If any of these questions can be answered, that would be great, if not, hopefully I'll have enough time to read through the thread and find the answers before the fabric goes up above the chair rail.


----------



## allredp




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13523740
> 
> 
> Depending upon the fabric, of course, a fabric covered wall can look quite attractive and classy. This is based upon a dealer showroom example I've seen using a GOM Anchorage fabric with has a subtle texture to it. Looked elegant, with the added benefit of disguising all the wall treatments hidden behind it.
> 
> 
> In other words, I agree.



Yeah, my wife has seen the fabric and is still adamant about not having a "pillowed-room" look.


BTW, the Anchorage is not AT, right? But, that's ok because the upper part is not meant to be "dead" anyway, right?


Thanks for the suggestions and all the help.


One more question: what's the deal with *soffits*?


I see them in most professional rooms and so many of the DIY rooms here! I can't tell if very many have bass-trapping in them, but they are everywhere.


Is that something I should be looking at for my room _acoustically_, or is it mostly for aesthetics and lighting options, etc.?


Thanks!


----------



## Ethan Winer




> Quote:
> Originally Posted by *brianhutchins* /forum/post/13540755
> 
> 
> the rear of the theater ... will be open to my large pool table, bar, card table room.



An opening that gives a lot of space behind you is a Good Thing. The most damaging reflections at bass frequencies come from the wall behind you. So the farther back that wall is, the better.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *Anthony1* /forum/post/13545233
> 
> 
> First, I want to apologize for not reading this thread from beginning to end



No need to apologize. This thread is way too long, is full of conflicting and often wrong information, and has long overstayed its welcome IMO.











> Quote:
> 1. When we are talking about first relection points, are we pretty much talking about the tweeter?



Yes, early / first reflections are mainly a mid and high frequency issue. But it's not a single reflection point as much as an area. 47 inches high is probably okay. Much more here:

http://www.realtraps.com/rfz.htm 


and here:

http://www.realtraps.com/art_room-setup.htm 


--Ethan


----------



## penngray




> Quote:
> BTW, the Anchorage is not AT, right? But, that's ok because the upper part is not meant to be "dead" anyway, right?
> 
> 
> Thanks for the suggestions and all the help.



allredp, what do you mean?


AT is acoustically transparent which is only meaningful if you are covering speakers with it. When just covering walls any material that is not reflective works very well. The goal is to simply allow sound to be absorbed by the panels.


btw, its funny your wife didnt want a pillow room







Mine said the same thing but when I showed her pics and showed her the material I will be using she was amazed. Although Im still having sticker shock with the anchorage GOM stuff....$17/yd???? Give me a break!!!


Its hard to hide 4x2 sheets of OC703 without something







and placing fabric panels around the room looks even worse unless you do panels everywhere and that is very time consuming.


----------



## allredp




> Quote:
> Originally Posted by *penngray* /forum/post/13548580
> 
> 
> allredp, what do you mean?
> 
> 
> AT is acoustically transparent which is only meaningful if you are covering speakers with it. When just covering walls any material that is not reflective works very well. The goal is to simply allow sound to be absorbed by the panels.
> 
> 
> btw, its funny your wife didnt want a pillow room
> 
> 
> 
> 
> 
> 
> 
> Mine said the same thing but when I showed her pics and showed her the material I will be using she was amazed. Although Im still having sticker shock with the anchorage GOM stuff....$17/yd???? Give me a break!!!
> 
> 
> Its hard to hide 4x2 sheets of OC703 without something
> 
> 
> 
> 
> 
> 
> 
> and placing fabric panels around the room looks even worse unless you do panels everywhere and that is very time consuming.



Hey Penngray,


Yes, I didn't mean behind the room, but just around the other three walls. I'm planning on packing 2" of Linacoustic behind my AT screen (as well as my center speaker--the Dali Mentor Vokal).


You know I tried to show her some pics, and it did help me with a few items, but she still isn't going for anything but paint and pictures above my dinky 38" height! You're so right about the individual panels bit...


I did get her to concede that I should have a couple columns in the back to balance out the room. I can fill them with mineral wool, floor to ceiling, though they won't be in the corners.


BTW, *what will two columns 16"W x 6"D x 7.8'H (floor to ceiling) filled with chunks of mineral wool do for bass-trapping?* They would be divided off-center on my back wall which is only 2-3' back from my listening position.


Appreciate the help!


----------



## allredp




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13548308
> 
> 
> An opening that gives a lot of space behind you is a Good Thing. The most damaging reflections at bass frequencies come from the wall behind you. So the farther back that wall is, the better.
> 
> 
> --Ethan



Hey Ethan,


What if your sub is placed right against the back wall?


Does that change where you want treatments?


I'll have 1" linacoustic all along the back wall where I'll have my sub firing sideways.


What do you think?


Thanks,

Phil


----------



## penngray




> Quote:
> You know I tried to show her some pics, and it did help me with a few items, but she still isn't going for anything but paint and pictures above my dinky 38" height! You're so right about the individual panels bit...
> 
> 
> I did get her to concede that I should have a couple columns in the back to balance out the room. I can fill them with mineral wool, floor to ceiling, though they won't be in the corners.



In the end my wife is okay with the HT build (if I ever finish it) but she did ask last night where the toy closet is going (we have a 16 month old!!)....yikes!!!










Columns might work really well for you!! They will be great for bass absorption!!


----------



## allredp




> Quote:
> Originally Posted by *penngray* /forum/post/13549599
> 
> 
> In the end my wife is okay with the HT build (if I ever finish it) but she did ask last night where the toy closet is going (we have a 16 month old!!)....yikes!!!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Columns might work really well for you!! They will be great for bass absorption!!



Funny! I remember well... Mine are all teenagers now, so it's about scheduling time between all the x-box and sleepovers, etc.


Anyone else have insight to my *column/bass-trap idea*?


----------



## CruelInventions




> Quote:
> Originally Posted by *allredp* /forum/post/13546109
> 
> 
> 
> One more question: what's the deal with *soffits*?
> 
> 
> I see them in most professional rooms and so many of the DIY rooms here! I can't tell if very many have bass-trapping in them, but they are everywhere.
> 
> 
> Is that something I should be looking at for my room _acoustically_, or is it mostly for aesthetics and lighting options, etc.?
> 
> 
> Thanks!



first about the Anchorage fabric; as mentioned a little while ago, yes, they are fine for allowing absorption to take place. In fact, I've seen this fabric given as an option on at least 2 or 3 acoustic treatment websites, as an "upgrade" to the standard GOM 701 series of fabrics.


re: soffits. I think they are used because they are one graceful way of secretly adding some extra trapping; thicker bass type trapping, mostly.


----------



## penngray




> Quote:
> re: soffits. I think they are used because they are one graceful way of secretly adding some extra trapping; thicker bass type trapping, mostly.




Also, they hide any ugly pipes, ducts, wires or whatever needs to be hidden.


----------



## CruelInventions




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13548349
> 
> 
> 
> 
> 
> Yes, early / first reflections are mainly a mid and high frequency issue. But it's not a single reflection point as much as an area. 47 inches high is probably okay. Much more here:
> 
> http://www.realtraps.com/rfz.htm
> 
> 
> and here:
> 
> http://www.realtraps.com/art_room-setup.htm
> 
> 
> --Ethan



Ethan, since neither of your links addresses it, I take it that you are not a proponent of treating the front wall?


----------



## SPDSpappy

I thought the Anchorage was AT (I sure hope so, since I was planning on using it in my false wall in front of speakers...)?


I'm using soffit's to put my can lights in so I'm not opening up huge holes in my DD ceiling.


----------



## Ethan Winer




> Quote:
> Originally Posted by *allredp* /forum/post/13548803
> 
> 
> What if your sub is placed right against the back wall? Does that change where you want treatments?



You mean front wall, yes? My sub is in the front left corner, and it's great there. I have bass traps in all corners, and for that corners the trap is above the sub.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13550058
> 
> 
> Ethan, since neither of your links addresses it, I take it that you are not a proponent of treating the front wall?



The front wall is as good a place as any for _general_ absorption to reduce ambience. But unless the room is really tiny it won't be much of a reflection place. I do in fact have an article about this:

http://www.realtraps.com/art_front-wall.htm 


--Ethan


----------



## CruelInventions




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13550504
> 
> 
> The front wall is as good a place as any for _general_ absorption to reduce ambience. But unless the room is really tiny it won't be much of a reflection place. I do in fact have an article about this:
> 
> http://www.realtraps.com/art_front-wall.htm
> 
> 
> --Ethan



ah, thanks.. I'll go and have me a look.


----------



## CruelInventions




> Quote:
> Originally Posted by *SPDSpappy* /forum/post/13550389
> 
> 
> I thought the Anchorage was AT (I sure hope so, since I was planning on using it in my false wall in front of speakers...)?



I think two people just confirmed that it was, one being me. So yes, don't fret about it, the Anchorage is AT.


----------



## CruelInventions




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13550504
> 
> 
> The front wall is as good a place as any for _general_ absorption to reduce ambience. But unless the room is really tiny it won't be much of a reflection place. I do in fact have an article about this:



ok, so by "ambience", you mean what, exactly? Just want to be sure I am understanding you correctly.


From your article, you don't seem high on the concept of front wall treatments*, UNLESS, you have speakers that just so happen to radiate enough mid to high frequencies off to the sides and rear to make it worthwhile, which most speakers apparently do not. Or, unless you have a multi-channel system with rear speakers pointing towards the front wall, in a room that is rather small. Have I accurately portrayed your philosophy on this matter?


I also take it that you would even go so far as to say that placing 4"+ wall panels on the front wall is not all that necessary either, particularly if you are able to sufficiently treat the corners of the front wall/ceiling with 4"+ corner panels or larger diameter tube traps, etc. Or to put it another way, would you advice placing 4"-6" wall panels on the front wall ONLY in situations where you are unable to adequately bass trap in the corners?


_*to be clear, I'm not including 4"+ corner bass trapping within that description of "front wall treatment"_


----------



## Anthony1

Regarding first reflection points, I did the mirror trick thing with a flashlight, and marked the points of first reflection with a tiny patch of blue painters tape. Here is a pic of it:











If you look closely at this picture, from left to right, you'll see three little strips of blue tape on the linacoustic. This wall, is to the right of the screen. The first blue strip, corresponds with the tweeter of my right Energy C8 tower speaker. The second blue strip, corresponds with the tweeter of my Energy AC300 center. The third blue strip, corresponds with the tweeter of the left Energy C8 tower speaker (on the opposite side of the room)


The center channel is really low because I need to build a proper stand for it, and it's on a temporary stand. However, I have to locate it below the screen, and it will only be about 10 inches higher, if that.


Anywho, the blue stips of painters tape towards the top, the reflections coming from the Energy C8 towers, are at about 38 inches or so off the ground, and the linacoustic goes up to 47 inches. Above the linacoustic is a 2 inch furring strip, and I could put additional linacoustic above the furring strip. Since the reflection of sound hits a general area of the wall, I was trying to figure out what might be the circumference of the reflection, to determine if part of the reflection is hitting above the furring strip, to the area that currently doesn't have any linacoustic on it.


I've heard that putting linacoustic above ear-level isn't necessary, but I've also heard that some people go floor to ceiling at the first reflection points. I'm going to be putting my fabric up very soon, and I'm trying to decide if I need to put any linacoustic above the furring strip at the 49 inch mark of the wall. (linacoustic is from floor to 47 inches up, and then the 2 inch furring strip).


I have a riser for the second row of seating, and the riser is approximately 13 inches off the ground, so i'm going to put an extra 13 inches of linacoustic above the furring strip parrallel to the riser, but was wondering if I should put any linacoustic above the furring strip anywhere else.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Anthony1* /forum/post/13551562
> 
> 
> Regarding first reflection points, I did the mirror trick thing with a flashlight, and marked the points of first reflection with a tiny patch of blue painters tape. Here is a pic of it:
> 
> 
> If you look closely at this picture, from left to right, you'll see three little strips of blue tape on the linacoustic. This wall, is to the right of the screen. The first blue strip, corresponds with the tweeter of my right Energy C8 tower speaker. The second blue strip, corresponds with the tweeter of my Energy AC300 center. The third blue strip, corresponds with the tweeter of the left Energy C8 tower speaker (on the opposite side of the room)
> 
> 
> The center channel is really low because I need to build a proper stand for it, and it's on a temporary stand. However, I have to locate it below the screen, and it will only be about 10 inches higher, if that.
> 
> 
> Anywho, the blue stips of painters tape towards the top, the reflections coming from the Energy C8 towers, are at about 38 inches or so off the ground, and the linacoustic goes up to 47 inches. Above the linacoustic is a 2 inch furring strip, and I could put additional linacoustic above the furring strip. Since the reflection of sound hits a general area of the wall, I was trying to figure out what might be the circumference of the reflection, to determine if part of the reflection is hitting above the furring strip, to the area that currently doesn't have any linacoustic on it.
> 
> 
> I've heard that putting linacoustic above ear-level isn't necessary, but I've also heard that some people go floor to ceiling at the first reflection points. I'm going to be putting my fabric up very soon, and I'm trying to decide if I need to put any linacoustic above the furring strip at the 49 inch mark of the wall. (linacoustic is from floor to 47 inches up, and then the 2 inch furring strip).



The wavelengths from a tweeter are pretty small, and I assume the tweeter on this speaker is located several inches above the lower frequency drivers. Because of the small wavelengths, there is very little spread at the first reflection points. So you should be fine with just fiberglass as it is now.


> Quote:
> I have a riser for the second row of seating, and the riser is approximately 13 inches off the ground, so i'm going to put an extra 13 inches of linacoustic above the furring strip parrallel to the riser, but was wondering if I should put any linacoustic above the furring strip anywhere else.



You should be okay here as well, as the reflection geometry should be much the same.


Regards,

Terry


----------



## Dan Woodruff

For those only treating the 1st reflection points, don't forget to do the "mirror/blue-tape-trick" for each seat.


----------



## SPDSpappy




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13550639
> 
> 
> I think two people just confirmed that it was, one being me. So yes, don't fret about it, the Anchorage is AT.



Sorry, the last one I saw I thought said that it was not AT...


----------



## allredp




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13550485
> 
> 
> You mean front wall, yes? My sub is in the front left corner, and it's great there. I have bass traps in all corners, and for that corners the trap is above the sub.
> 
> 
> --Ethan



Hey Ethan,


Actually I did mean "back" wall, as in the back of my room.


I currently have my sub in the front R corner (where it takes advantage of the corner boundary boost); however, I'm seriously considering moving it to the back of my room. I was told by another "pro" that for the best acoustics I really don't want my sub in a corner.


Frankly I'd love to move the sub to the rear for aesthetic reasons also--it is oversized for my space in the front R corner (due to a closet door







) and, it would look better (as in not be seen) in the back.


I've attached a couple pics to show what I mean in my room (15'D x 27'W x 7.8"H). Here's the spot in the back of my seating where I'm considering putting my SVS Ultra (with arrow to potential placement) Attachment 106662 and here's a pic of the front build-out plan where I'm going to be treating the behind the screen area with 2" of linacoustic Attachment 106663 . Notice too, that I'm running 1" linacoustic all the way around the room (shown by the goofy looking "boxes" I've drawn on the pic). I also plan to have some chunked trapping for my one corner in the room, and I'm also going to stuff two rear columns on my back wall full of mineral wool...


So, what are the advantages and disadvantages of a sub in the back of the room, behind, but close to the seating?


Help is much, much appreciated!


Thanks,

Phil


----------



## dbbarron

Subj: Acoustic Treatments (Cross post from Mayflower construction thread)


I took the time to sketch the as-built floorplan and estimated the longitudinal room modes for the different parallel surfaces. I have included them on the floorplan.


My question is whether the irregular parallel surfaces (e.g., the room length has a 22' section at longest, but only 18.5' for the outer 3.5' on each side.) weakens the dominant modes and helps me out or just introduces more strong modes.


From the floorplan, the lenght, width and height are substantially broken up by various room features.


If I do install bass traps (I'll have measurements by next week - carpet goes in tomorrow), any suggestions where? I'm thinking superchunks in the rear corners (under the soffits) and maybe on the stage in the corners against the front wall.


Any other predictions from the group at large?


db


----------



## Ethan Winer




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13551087
> 
> 
> ok, so by "ambience", you mean what, exactly?



Ambience is like reverb, but the term is more appropriate to domestic size rooms that don't have true reverb as you'll find in an auditorium or gymnasium. So ambience is really more a collection of individual reflections that decay quickly over time. But those reflections still make a muddy mess of the sound in much the same way reverb does in a gymnasium. It's just that the decay times are shorter. And ambience doesn't swell initially over time the way true reverb does.



> Quote:
> Have I accurately portrayed your philosophy on this matter?



Yes.



> Quote:
> I also take it that you would even go so far as to say that placing 4"+ wall panels on the front wall is not all that necessary either, particularly if you are able to sufficiently treat the corners of the front wall/ceiling



Thick absorbers on the walls are still useful because they give that much more bass trapping in the room. The main point of my Front Wall article addresses the inadequacy of 1-inch thick material which is very common in DIY home theaters. Even two inches is not thick enough to help at bass frequencies. In my mind (uh oh) the ideal room will have 12-inch thick fiberglass on all walls and the ceiling, but with portions covered by cardboard or thin plastic etc (or reflective diffusors) to avoid being totally dead.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *allredp* /forum/post/13554519
> 
> 
> I was told by another "pro" that for the best acoustics I really don't want my sub in a corner.



Here's my take on that:

http://www.realtraps.com/art_sub-placement.htm 



> Quote:
> what are the advantages and disadvantages of a sub in the back of the room, behind, but close to the seating?



I can theorize a few pros and cons, but I've never actually tried that so it would not be an informed opinion. My gut feeling is it's better to have the sub closer to the mains in the front of the room. As explained in the article linked above, the _only_ way to know for sure is to measure the LF response at high resolution.


--Ethan


----------



## Anthony1

Regarding subs, what's the way to go if you're using two of them? For some reason, I was under the impression to have them located in completely opposite corners. I have one sub in my front left corner, and one sub in my back right corner. Basically, in completely opposite corners. Not sure why I thought that this was the way to do it.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Anthony1* /forum/post/13559177
> 
> 
> Regarding subs, what's the way to go if you're using two of them? For some reason, I was under the impression to have them located in completely opposite corners. I have one sub in my front left corner, and one sub in my back right corner. Basically, in completely opposite corners. Not sure why I thought that this was the way to do it.



Don't know why you thought this either.










Multiple sub placement is a complex subject. For a place to start, there is Floyde Toole's white paper:

http://www.harmanaudio.com/all_about...kers_rooms.pdf 


He has a basic discussion of room modes and how two subs can help.


There is no generally agreed upon procedure, though. Rooms are different, no simple sub configuration can solve all problems. Side sub placement can increase envelopment, but does necessarily improve room modes. More than one sub removes the option of the "crawl" technique, by which you exchange places with your sub and find a good spot easier. Dennis E. advocates a dual sub placement method developed by Gerry Lemay, which kinda sorta works. Etc., etc.










Regards,

Terry


----------



## dbbarron

I went for the four sub design (two on front wall and two on back at 1/2, 2/3 position on each).


Will have testing next week.


----------



## armstrr

ok, so i have actually tried to read some of this thread. i understand that a dead front wall is a good thing and more than 2" of fiberglass is recommended. i am insulating my walls with cellulose behind a material called insulmesh. i will have about 6" of it behind all my walls. would it make sense to NOT cover this insulation on the front wall? i will have a false wall covered with black speaker grill fabric. is this a good idea?


this insulation procedure is called dense packing by regal industries (google for more info). so is cellulose any good or should i do that wall in fiberglass?


----------



## Terry Montlick




> Quote:
> Originally Posted by *armstrr* /forum/post/13562708
> 
> 
> ok, so i have actually tried to read some of this thread. i understand that a dead front wall is a good thing and more than 2" of fiberglass is recommended.



By one person, anyway.











> Quote:
> i am insulating my walls with cellulose behind a material called insulmesh. i will have about 6" of it behind all my walls. would it make sense to NOT cover this insulation on the front wall?



You mean not using inner sheetrock? That would be a gross code violation, not to mention a bad idea in general. You would loss any possible sound isolation.










Regards,

Terry


----------



## armstrr




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13562860
> 
> 
> By one person, anyway.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You mean not using inner sheetrock? That would be a gross code violation, not to mention a bad idea in general. You would loss any possible sound isolation.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards,
> 
> Terry



its a basement theater, so there's poured concrete walls on 3 sides, the front wall being one of them.


----------



## Terry Montlick




> Quote:
> Originally Posted by *armstrr* /forum/post/13563272
> 
> 
> its a basement theater, so there's poured concrete walls on 3 sides, the front wall being one of them.



Once you finish the space, it is now "habitable," and other code regulations kick in. Of course, you don't have to have it inspected. But there could be a problem later, in selling the house to a buyer skeptical of what you have done.


But potentially more important is the sound isolation problem. The concrete walls conduct sound to the upper part of your house, and stud walls with sound isolation construction are necessary to deal with this.


Regards,

Terry


----------



## armstrr

the stud wall above is for the garage. i'm not worried about sound travel as this end of the house is not used for much. i am doing some sound abatement, however, more cellulose.


code and sound isolation aside, how would this cellulose behave compared to fiberglass?


thanks


----------



## Terry Montlick




> Quote:
> Originally Posted by *armstrr* /forum/post/13564867
> 
> 
> code and sound isolation aside, how would this cellulose behave compared to fiberglass?
> 
> 
> thanks



While not the equal of fiberglass, a few inches of thickness would probably provide very good, wide-frequency sound absorption. Exact performance depends on density of packing and specific material, etc.


Regards,

Terry


----------



## dbbarron

Below are my first room measurements. (room is complete except for treatments - see Mayflower Construction thread); fyi, tried to measure STC of the room - first very rough measurement is about 40db for mid frequencies and 30+db for low frequencies. Room is double 5/8+GG w/steel studs and fully insulated. Oh well.


Subjectively, there are lot of higher frequency reflections within the stage alcove containing the LCR speakers. I can walk into that space and hear the increased ambiance.


Also, when music is playing, the whole room, and particularly the alcove inside corners sound very heavy - lots of bass buildup in the inside corners of the alcove. I don't 'hear' any bass buildup in any other room corners.



Floor Plan











Speaker Freqency Response at 1/2m (1/3 oct smooth).










Speaker Freq Response at listening position (1/3 oct smooth)










RT60 at listening position










For initial treatments prior to re-evaluation, it would seem like I need to treat the entire alcove for high and low frequency as a start. Perhaps thinker treatments across the entire alcove walls or just 1" on walls and super chunks in alcove corners?


Comments appreciated.


db


----------



## CruelInventions




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13523740
> 
> 
> Depending upon the fabric, of course, a fabric covered wall can look quite attractive and classy. This is based upon a dealer showroom example I've seen using a GOM Anchorage fabric with has a subtle texture to it. Looked elegant, with the added benefit of disguising all the wall treatments hidden behind it.
> 
> 
> In other words, I agree.



Quoting myself, because I *AM* that important







, I need to make one small correction. There is no real texture to the Anchorage fabric.. it turns out what I thought was Anchorage, was actually a GOM fabric group called "Shagreen" instead. Just in case anybody was keeping track.


----------



## CruelInventions




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13558252
> 
> 
> ........Thick absorbers on the walls are still useful because they give that much more bass trapping in the room. The main point of my Front Wall article addresses the inadequacy of 1-inch thick material which is very common in DIY home theaters. Even two inches is not thick enough to help at bass frequencies. In my mind (uh oh) the ideal room will have 12-inch thick fiberglass on all walls and the ceiling, but with portions covered by cardboard or thin plastic etc (or reflective diffusors) to avoid being totally dead.
> 
> 
> --Ethan



Ok, thank you for the clarifications (and confirmations).


----------



## penngray




> Quote:
> Regarding subs, what's the way to go if you're using two of them? For some reason, I was under the impression to have them located in completely opposite corners. I have one sub in my front left corner, and one sub in my back right corner. Basically, in completely opposite corners. Not sure why I thought that this was the way to do it.



Not sure if this is the thread for sub location discussion but I guess it does relate a little to acoustics










I have two subs and I will be placing them side by side to double the output. I have read that if you place them on opposite ends or complete apart you could have phase issues, etc and the output doesnt double if they are separate by so many feet.


----------



## penngray




> Quote:
> ........Thick absorbers on the walls are still useful because they give that much more bass trapping in the room. The main point of my Front Wall article addresses the inadequacy of 1-inch thick material which is very common in DIY home theaters. Even two inches is not thick enough to help at bass frequencies. In my mind (uh oh) the ideal room will have 12-inch thick fiberglass on all walls and the ceiling, but with portions covered by cardboard or thin plastic etc (or reflective diffusors) to avoid being totally dead.



Very interesting because Im doing that "inadequate" 1" on my walls










but also.....


Im building 3 corner traps too. Triangle traps, 6 feet high, 12"x12"x17", filled with Rockwool60. I can not do 4 corners because I have a door in the way but the door is going to have 4" worth of 2x4 rockwool 60 too, one more thick bass trap!


I believe these bass traps will handle my bass neede, I HOPE!







Its a 13x24 room.


----------



## dbbarron

Further to my prior post, I have measured some higher resolution spectra placing the mic in the front left alcove corner. (I measured in every corner and in this one all the modes are by far the most pronounced).


Again for reference, the floor Plan











Here is the front left corner (in alcove) spectra










The dark blue is the native measurement; the light green is with a large duffel stuffed with blankets and towels in the right front alcove corner.


Taking the modes from left to right:

25 Hz - This mode appears to correspond to room dimensions of the theater plus playroom outside it as demarked by concrete walls. It is small at the LP, and some room lift at this freq is not entirely undesirable - Other treatments may mitigate this mode some - otherwise leave alone.


52 - This mode appears to correspond to the room length. As the back wall should remain unabsorbitive, This can be treated by (1) super chunks in the rear corners or (2) super chunks in the front alcove corners or (3) heavy aborbtion on the screen wall.


78, 169 - I believe these dips correspond to modes relating to the floor to ceiling distances. The floor is carpeted with heavy pad (only absorbtion in room right now). What can I do about this? Strangely enough, the dips are worse with the duffel in place.


120 - Corresponds exactly to the wide of the alcove containing the stage and LCRs. Clearly the duffel bag help this greatly. I believe super chunks in the alcove corners or heavy treatment of the alcove side walls and front wall will help this.


In view of all the above, I plan to pickup some 2'x4'x4" mineral board this week (local mechanical insulation contractor) and experiment some more. I know there is mixed opinion on 4" front wall treatment, but in my case, I think treating the whole alcove (sides of alcove and front wall of alcove) with 4" may solve everything at once with the danger of it being too absorbitive of higher frequencies. Any comments on this point.


Treating the front wall should also bring my overall RT60 down into the 0.34 range. In that regard, some minor 1" treatments of the first reflection points may be all I need after this front wall/alcove work.


Comments appreciated.


db


----------



## Franin

Id just like to say that previously I thought HT was about good equipment equalling awesome sound.I then assumed audyssey was the way to go.But I was wrong, I recentley had a manual calibration (HAA is what we call over here using sencore units) and the difference was clearly night and day.Im just awaiting the room treatment,hopefully next week which I've been told it's even going to improve it more.But you guys on this particular thread are definetley on the ball when it comes to HT, there are many people out there that still believe audyssey(eq) is the way to go.I don't even use it anymore.

Sorry to take off topic, just very excited!


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13568568
> 
> 
> Not sure if this is the thread for sub location discussion but I guess it does relate a little to acoustics
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have two subs and I will be placing them side by side to double the output. I have read that if you place them on opposite ends or complete apart you could have phase issues, etc and the output doesnt double if they are separate by so many feet.



I presently have dual subs placed within one RADIUS (of the driver) so they couple. They are behind my false wall 1/3 the room width from the side wall. Audyssey and SVS are close to releasing a device that will optimize two non-co-located subs for both level, phase, EQ and time domain EQ. When they do that, I will set up an identical pair in the rear.


----------



## Alex solomon

I recently bought some Revel Performa speakers and I found them to be a little to bright for my taste. I think I like warm sounding speaker and I love My Mirage speakers a lot. so I want to treat the room to get the best out of them. I am about to purchase some bass traps (also called broadband traps??) to treat my L-shaped room. I am going to place some traps on the front wall behind my Omnipolar speakers (Mirage OM-9 and OM-C2) and hang some bass traps on the rear wall ( I have OM-R2 x 4 surrounds here). Is this going to cause too much adsorption and defeat the Omnipolar characteristics of a speaker? I googled but nothing came up. I wonder if Ethan, Glenn, Bryan or Mirage owners chime in here. Thanks for your help.


BTW, the front and back wall are the only two places I can put any kind of treatment. Unfortunately I 'm married!!


----------



## Franin




> Quote:
> Originally Posted by *Alex solomon* /forum/post/13584688
> 
> 
> I recently bought some Revel Performa speakers and I found them to be a little to bright for my taste. I think I like warm sounding speaker and I love My Mirage speakers a lot. so I want to treat the room to get the best out of them. I am about to purchase some bass traps (also called broadband traps??) to treat my L-shaped room. I am going to place some traps on the front wall behind my Omnipolar speakers (Mirage OM-9 and OM-C2) and hang some bass traps on the rear wall ( I have OM-R2 x 4 surrounds here). Is this going to cause too much adsorption and defeat the Omnipolar characteristics of a speaker? I googled but nothing came up. I wonder if Ethan, Glenn, Bryan or Mirage owners chime in here. Thanks for your help.



Ill be using fonics, they also have a very nice cosmetic look to them.


----------



## Alex solomon




> Quote:
> Originally Posted by *Franin* /forum/post/13584742
> 
> 
> Ill be using fonics, they also have a very nice cosmetic look to them.



Sorry, I am new to this but what are fonics?


----------



## aaronlinkous




> Quote:
> Originally Posted by *Alex solomon* /forum/post/13584768
> 
> 
> Sorry, I am new to this but what are fonics?



googled, appear to be an australian company for panels

http://www.fonic.com/


----------



## Alex solomon




> Quote:
> Originally Posted by *Franin* /forum/post/13584742
> 
> 
> Ill be using fonics, they also have a very nice cosmetic look to them.



Thanks for your reply but that is just a product recommendation and does not answer my question.


----------



## pepar




> Quote:
> Originally Posted by *Alex solomon* /forum/post/13584688
> 
> 
> I recently bought some Revel Performa speakers and I found them to be a little to bright for my taste. I think I like warm sounding speaker and I love My Mirage speakers a lot. so I want to treat the room to get the best out of them. I am about to purchase some bass traps (also called broadband traps??) to treat my L-shaped room. I am going to place some traps on the front wall behind my Omnipolar speakers (Mirage OM-9 and OM-C2) and hang some bass traps on the rear wall ( I have OM-R2 x 4 surrounds here). Is this going to cause too much adsorption and defeat the Omnipolar characteristics of a speaker? I googled but nothing came up. I wonder if Ethan, Glenn, Bryan or Mirage owners chime in here. Thanks for your help.
> 
> 
> BTW, the front and back wall are the only two places I can put any kind of treatment. Unfortunately I 'm married!!



Broadband absorbers are just that - broad in the range of frequencies absorbed. I've never heard them called "traps." Bass traps of the foam or fiberglass variety (or a few more similar materials) do absorb broadly, but due to the usually small surface area, they do not provide significant absorption at mid and higher frequencies for the purposes of reducing reverb time. And they are placed in corners. Broadband absorbers are typically hung on walls, first at first reflection points and then other locations as needed.


Honestly, in my opinion, the treatment necessary for a good sounding home theater flies in the face of what omnipolar speakers are all about. Many of us have an entirely dead room front, so - poof - there goes the reflections from the front wall. Again, just my opinion . . .


----------



## dbbarron

(see prior posts for room description and initial testing)


I hooked up my four subs tonight - located at the 1/3 and 2/3 position on the front and rear wall.


I compared this to the output of my center channel speaker below.











The top response are the four subs, the bottom response is the center channel. All measured at the listening position. No averaging.


The subs are crossed over to the center channel at 80Hz.


Note the substantial decrease in room mode effect below 100Hz. Did not think it would be so pronounced. This is WITHOUT any room treatment. With the four subs, the 25 Hz mode is gone; the 78Hz dip is substantially mitigated and the remainder of the response is all together nicer. Room treatments should fix this up even more and address the 100hz+ issues (which are easier to deal with using absorbtion than the lower frequencies).


Please also note that the center speaker rolls off below 50Hz; the subs is designed with the 20Hz boost seen - I intent to EQ this to taste.


db


----------



## Anthony1

I started my own thread about this, but so far have no replies in that thread, so I might as well post it in this thread too. Basically, I'm trying to get some opinions on using linacoustic above 4 feet from the floor. I know, normally it isn't recommended to use any linacoustic above ear level, but was wondering if there is certain situations when it makes sense to use it above the 4 foot mark.



Here are my questions:


1. Put 2 feet (width) of linacoustic from floor to ceiling on the side walls right next to the corner?


2. Put 13 inches of linacoustic above the chair rail, parrallel to the riser (or actually where people sitting on the riser would get their first relections). The 13" extra of linacoustic would make sure it was above their ear level. Yes or No?


3. Put linacoustic in the area behind the side surround speakers?


4. Put linacoustic above 4 feet at the points of first reflection to account for the radius of the reflection, part of which is above the 4 foot level?





I'm trying to get any opinions or feelings on these questions, because yesterday and the day before I installed my fabric on the lower sections of the side walls. (to the chair rail). Today and tomorrow, I'm supposed to do the top portion. But before I start stapling the fabric up, I need to put any linacoustic above the chair rail, where it makes sense. Once I get my fabric stapled up, there's no going back.


----------



## Alex solomon




> Quote:
> Originally Posted by *Alex solomon* /forum/post/13584688
> 
> 
> I recently bought some Revel Performa speakers and I found them to be a little to bright for my taste. I think I like warm sounding speaker and I love My Mirage speakers a lot. so I want to treat the room to get the best out of them. I am about to purchase some bass traps (also called broadband traps??) to treat my L-shaped room. I am going to place some traps on the front wall behind my Omnipolar speakers (Mirage OM-9 and OM-C2) and hang some bass traps on the rear wall ( I have OM-R2 x 4 surrounds here). Is this going to cause too much adsorption and defeat the Omnipolar characteristics of a speaker? I googled but nothing came up. I wonder if Ethan, Glenn, Bryan or Mirage owners chime in here. Thanks for your help.
> 
> 
> BTW, the front and back wall are the only two places I can put any kind of treatment. Unfortunately I 'm married!!



Someone with experience with Omnipolar speakers and acoustic treatment please chime in!


----------



## Anthony1

Oh, I should probably mention that my side surrounds are direct radiating. So, I'm not trying to bounce sound off the side walls on purpose.


----------



## pepar




> Quote:
> Originally Posted by *Anthony1* /forum/post/13605641
> 
> 
> I started my own thread about this, but so far have no replies in that thread, so I might as well post it in this thread too. Basically, I'm trying to get some opinions on using linacoustic above 4 feet from the floor. I know, normally it isn't recommended to use any linacoustic above ear level, but was wondering if there is certain situations when it makes sense to use it above the 4 foot mark.



It is sooo easy to over-deaden a small room. I can't think of any situation where I would apply absorption above ear level, at least not the entire area.


----------



## bpape

Omni's in a home theater environment are just not optimal. As has been said, to properly treat a hometheater, the front wall needs to be pretty dead to keep the surround channel reflections from mixing with and smearing the front soundstage. This is the same reason that rear tweeters and speakers like Maggies and ML's don't work the best for home theater duty.


Most of the Revel's are pretty neutral in the frequency response realm. Sounds to me like you want something that's more rolled off rather than neutral. If that's the case, then it sounds like the choice is a speaker that's more laid back but still a direct radiator.


Bryan


----------



## Alex solomon

^^^Thanks, Bryan.


----------



## Anthony1




> Quote:
> Originally Posted by *pepar* /forum/post/13607200
> 
> 
> It is sooo easy to over-deaden a small room. I can't think of any situation where I would apply absorption above ear level, at least not the entire area.



My room is 19.9' wide x 26' long x 8'3" high. Would this be considered a small room? What about the whole poly batting thing? Some people have said that putting poly batting above your linacoustic is a waste of time and money, from a performance aspect, but if you want to do it, to maintain a consistent 1 inch thickness, along with the linacoustic, for aesthetic purposes, then go ahead.


I was going to get the poly batting until I heard that.


----------



## penngray




> Quote:
> What about the whole poly batting thing? Some people have said that putting poly batting above your linacoustic is a waste of time and money, from a performance aspect, but if you want to do it, to maintain a consistent 1 inch thickness, along with the linacoustic, for aesthetic purposes, then go ahead.
> 
> 
> I was going to get the poly batting until I heard that.




I was told that too and I do believe it doesnt have much acoustical absorption value (not enough to matter, just high freq stuff) but Im doing fabric on all my walls so when I put a 1" furring strip up and staple the fabric to it, I will want something about 1" thick so that I dont have fabric slack, fabric sagging and so on. Plus, my corner basstraps are going to be 100% of the corner so to get a nice flow of color, etc Im using fabric on all walls.


Using fabric on upper walls seems to be very popular and it looks better then solid color painted walls from a HT perspective but that is obviously subjective.


Just having painted walls on the upper portion should be 100% okay.



I wonder what absorption value egg crate foam has???? I have picked up some for my two Sub DIY projects but Im now thinking that it might be okay to use on the upper walls. Its denser and seems to create less of a "pillow" effect. Does it absorb too much sound...maybe I should put reflect substrate on top of it? as usual, Im confused!!!!!


----------



## Anthony1




> Quote:
> Originally Posted by *penngray* /forum/post/13609138
> 
> 
> but Im doing fabric on all my walls so when I put a 1" furring strip up and staple the fabric to it, I will want something about 1" thick so that I dont have fabric slack, fabric sagging and so on.




You know, after just stapling a bunch of fabric yesterday and the day before, I'm not too sure if there really would be any slack or sagging. The staples are what holds the fabric in place. The key, is to be pulling on the fabric enough to keep it super tight, but not enough to mess it up, and then while it's like that, staple it to the furring strips. Once that is done, I don't think whether or not you have anything underneath the fabric is going to matter at all in terms of sagging and slack.


Now, having said that.... If you have kids, you might want to have something under the fabric, so if they touch the walls, it's like they are touching something with substance, and they don't poke at it, and make a hole in it or something. Since I have a 5 year old and 7 year old, I might should worry about that a bit. Right now, it would be hard for them to do much of any damage to the fabric above my chair rail, and below the chair rail is all linacoustic, so hopefully they won't be able to puncture that, but eventually as they grow taller, they could touch the top part, and if there isn't anything behind the fabric, it could be easier to puncture the fabric accidentally.


----------



## pepar




> Quote:
> Originally Posted by *Anthony1* /forum/post/13609070
> 
> 
> My room is 19.9' wide x 26' long x 8'3" high. Would this be considered a small room? What about the whole poly batting thing? Some people have said that putting poly batting above your linacoustic is a waste of time and money, from a performance aspect, but if you want to do it, to maintain a consistent 1 inch thickness, along with the linacoustic, for aesthetic purposes, then go ahead.
> 
> 
> I was going to get the poly batting until I heard that.



Almost any room in a residential setting is going to be "small." Movie theaters and concert venues are "large." Personally, I would determine what was needed to "sound good" and then try to make it "look good." When the lights are off, it all comes down to the picture and the sound.


----------



## BasementBob

Alex solomon:


re omni-polars

http://www.bobgolds.com/SpeakerTests/20060810/home.htm


----------



## Kevin_Wadsworth




> Quote:
> Originally Posted by *Anthony1* /forum/post/13609535
> 
> 
> You know, after just stapling a bunch of fabric yesterday and the day before, I'm not too sure if there really would be any slack or sagging. The staples are what holds the fabric in place. The key, is to be pulling on the fabric enough to keep it super tight, but not enough to mess it up, and then while it's like that, staple it to the furring strips. Once that is done, I don't think whether or not you have anything underneath the fabric is going to matter at all in terms of sagging and slack.



Exactly. I bought batting having read these forums and started putting it up on my walls when I realized that it wasn't doing anything - nothing acoustical and nothing structural. It doesn't even have the firmness of linacoustic, so I don't think it will do much to help with kids hands on the wall either. So I stopped putting it up and never looked back.


Unfortunately, I lost me Jo-ann's receipt and they aren't nearly as forgiving as Lowes/HD. So if anyone still wants to put up abtting andlives in central Ohio...


----------



## Terry Montlick




> Quote:
> Originally Posted by *Kevin_Wadsworth* /forum/post/13613843
> 
> 
> Exactly. I bought batting having read these forums and started putting it up on my walls when I realized that it wasn't doing anything - nothing acoustical and nothing structural.



Well, the batting is providing modest amounts of absorption, particularly at high frequencies. Whether or not you *need* this absorption is another matter. Many people use batting sucessfully. I prefer to acoustically measure a room, model what it actually needs, and prescribe specific acoustical treatments accordingly.


Regards,

Terry


----------



## penngray




> Quote:
> Now, having said that.... If you have kids, you might want to have something under the fabric, so if they touch the walls, it's like they are touching something with substance, and they don't poke at it, and make a hole in it or something.



That is my worry even with adults. Someone will place their hand on the wall and it will feel weird, wont it?


Over time too I believe it will sag, no matter how much we think we stretch the fabric when installing I believe it may stretch further over long periods of time if push on. The "padding" may help with this, then again it may not.


Decisions, decisions, decisions.....


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13613892
> 
> 
> Well, the batting is providing modest amounts of absorption, particularly at high frequencies. Whether or not you *need* this absorption is another matter. Many people use batting sucessfully. I prefer to acoustically measure a room, model what it actually needs, and prescribe specific acoustical treatments accordingly.
> 
> 
> Regards,
> 
> Terry



Gosh, what a novel concept - use science.


----------



## penngray




> Quote:
> I prefer to acoustically measure a room, model what it actually needs, and prescribe specific acoustical treatments accordingly.
> 
> 
> Regards,
> 
> Terry





> Quote:
> Gosh, what a novel concept - use science.




Measuring means that the room has to have funiture, carpet and so on before any fabric is up so are you saying the acoustical treatments are the last thing installed.


and what DIY measuring tools are available, outside of flash lights and mirror tricks?


Measuring and modelling is more of a profession install and costs thousands of $$$, I think many DIYers are not going to spend that and are looking to get "best guess" solutions.


In anything there is a diminished returns theory that can be applied. If we place enough 1" around the bottom half of our rooms, full 1" on the screen, speakers front wall and thick bass traps in corners are we not creating a pretty good acoustical room that is probably 90% effective??


That 90% improvement for most of us is far more then we can ever dream to start with. The last 10% are for those who still want to listen too Vinyl


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13614767
> 
> 
> Measuring means that the room has to have funiture, carpet and so on before any fabric is up so are you saying the acoustical treatments are the last thing installed.
> 
> 
> and what DIY measuring tools are available, outside of flash lights and mirror tricks?
> 
> 
> Measuring and modelling is more of a profession install and costs thousands of $$$, I think many DIYers are not going to spend that and are looking to get "best guess" solutions.
> 
> 
> In anything there is a diminished returns theory that can be applied. If we place enough 1" around the bottom half of our rooms, full 1" on the screen, speakers front wall and thick bass traps in corners are we not creating a pretty good acoustical room that is probably 90% effective??



If you do that, you will be creating a dead room. I'm a DIY'er myself. I have a completely dead front and I put carpet on the walls below ear level; I wish I hadn't. I recommend that DIY'ers go s-l-o-w in adding treatments beyond first reflection points and bass traps.


----------



## penngray




> Quote:
> If you do that, you will be creating a dead room. I'm a DIY'er myself. I have a completely dead front and I put carpet on the walls below ear level; I wish I hadn't. I recommend that DIY'ers go s-l-o-w in adding treatments beyond first reflection points and bass traps.



wow, really










Learn as we go but Im happy (for this reason) to be addicted to the forum and slow at getting the room done!!


Okay, now back to the details because Im confused once again! you room is too dead, with just a dead front (is that 1" or 2") and carpet on the lower walls (38" and below) ??


I thought leaving the top half of the walls reflective made sure the room wasnt dead? and I figured I would just place 2x4 OC 703 1" every 2 feet around the bottom, catching the refection points.


Sounds like no matter what Im doing I am better off finishing the funiture, carpet and so on before doing the acoustical stuff


but now there is "schedule" conflict. Baseboard goes in before carpet usually (no?) but I can not put the baseboard on until the OC703 and fabric is up....grrrrrrr!!!


Here was my quick DIY best guess from all the reading and all the happy HT owner posts...I was happy until today











First relection points cover.....use Mirror, flash light to find them....check!!

Add OC703 1" to the whole front wall.....check!!

Add OC703 1" along the wall behind the row of seating (I have one row and its 2 feet from the back wall)...check!!

three corners will have 12"x12"x17" 6 foot tall rectangle bass traps...check!! Last corner has a door so I will add 4" of OC703 to the door itself....check!!

What ever gaps I have on the lower sections I was going to fill with poly batting or eggcrate foam. I wanted a uniform 1" area so I can place fabric over it all.


----------



## dbbarron

I think one must (within your resources) first set some design goals, then in a planned iterative process, measure, treat, measure, treat, measure, treat, measure.


I took baseline measurements and then decided I would first treat room modes (bass absorbtion), remeasure and then address the screen wall, then remeasure and then address first reflection points. If my RT60 is falling too fast, I would go lighter (but adequate) on treatment at the next iterative point.


As an example, corner treatments with 4" roxul appears to have sufficiently addressed bass modes, but has already lowered my RT60 from .42 to .35. This is prior to the screen wall treatment. If after the screen wall treatment, I am in the .2-.3 range of RT60, I will not treat the whole lower side walls, but use strips of absorbtion at 1st reflection points to insure the room does not get 'too dead'.


Also - what is 'too dead' - it would be nice to have some objective criteria. For my purposes, 'too dead' is an RT60 below 0.20.


db


----------



## penngray




> Quote:
> Also - what is 'too dead' - it would be nice to have some objective criteria.



Very true, I have spent a long time reading HT threads to get ideas and so on and one thing I have noticed is that MOST do have OC703 1" or similar all over the bottom half of the walls and from the results posted people love their theaters so if most are doing it and are happy, Im hoping I will be happy too.


pepar's comments was the first time I read someone saying they did too much, maybe I have missed the rest though. Pepar has a great point about doing too much so I want to make sure I dont have it all wrong.




> Quote:
> I think one must (within your resources) first set some design goals, then in a planned iterative process, measure, treat, measure, treat, measure, treat, measure.



That will be just too teadious for me, I simply wont go over it more then once. I was hoping that there is a "blueprint" too it and there are several articles to that effect that have helped me tremendously.


I can always do it and if it sucks too much I will remove the fabric, place tin foil or something similar over parts of the walls to change it.


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13614767
> 
> 
> Measuring means that the room has to have funiture, carpet and so on before any fabric is up so are you saying the acoustical treatments are the last thing installed.



Not really. We routinely measure rooms with just drywall. Acoustical modeling allows us to place any furniture the client likes in them, and then specify treatment.



> Quote:
> Measuring and modelling is more of a profession install and costs thousands of $$$, I think many DIYers are not going to spend that and are looking to get "best guess" solutions.



Not from us it certainly doesn't! If you want "the works" -- sound isolation, HVAC, 3D rendering, then yes. But many people go with as much analysis as they think they need or can afford.



> Quote:
> In anything there is a diminished returns theory that can be applied. If we place enough 1" around the bottom half of our rooms, full 1" on the screen, speakers front wall and thick bass traps in corners are we not creating a pretty good acoustical room that is probably 90% effective??



Maybe yes, maybe no. Certainly, if you want a completely DIY project, you "takes your chances" in not having a professional involved in the pretty technical field of acoustics. Of course, this can be part of a trial-and-error learning process which many people enjoy.


Regards,

Terry


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/13614816
> 
> 
> If you do that, you will be creating a dead room.



Interesting. I had gotten the impression that for Home Theater (*not* for music) a pretty dead room was pretty desirable. Do you find that the room being dead is a problem with accurate sound reproduction during movies, or that it makes the room feel uncomfortable while not watching? Or is this a music listening room for you as well?


In my case (working with bpape), I'll have dead front/rear walls (2" 703), and essentially 1" 703 up to 5' on left and right walls (full height behind the screen to 3' in front of the screen). That sounds pretty close to the room described by penngray (front covered, half-height on side walls). I'll actually have a bit more than he has (and some big bass traps in all corners).


I'm not too worried about over doing it, however. All of my treatments (except for the bass traps) will be in framed panels on the walls, with the panels going floor to ceiling. I'll be able to adjust the treatment amount later if needed after measuring. I plan to go wild with the PC/sound-card/mike measurements, although I've got no idea if I'll be able to do any useful analysis...


----------



## dbbarron

Paul:


It appears you are spending lots of time and resource on the project. Suggest you go over to hometheatershack.com and get a copy of REW (room eq wizard) and read the forums. For the cost of a calibrated mic and mic preamp (about $100 total), you can have quite an effective measuring system.


There are simply too many variables to consider to conclude how any particular room will behave without measuring it.


db


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13615268
> 
> 
> Okay, now back to the details because Im confused once again! you room is too dead, with just a dead front (is that 1" or 2") and carpet on the lower walls (38" and below) ??
> 
> 
> I thought leaving the top half of the walls reflective made sure the room wasnt dead? and I figured I would just place 2x4 OC 703 1" every 2 feet around the bottom, catching the refection points.



It's a small room. Did I mention that it's too easy to over deaden a small room?










The thick rug/foam backing covering the floor between the first row and the screen is being removed. And since I lowered my LCR to very close to ear level, I will be trimming my front L&R first reflection point absorbers - 2" OC SelectSound Black covered with GOM - from 48x48 to 24x48 and am seriously considering installing diffusion (Skyline LP looks interesting) above the new absorber to cover the underlying carpet. I do not have a completely dead room, but I feel as though I need put a little air into it. Also, I'd like to increase the sense of envelopment from my side surrounds - dipoles.


Following my own recommendation to go slow, I will yank the rug and trim the front/side absorbers before adding any diffusors.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/13616679
> 
> 
> Interesting. I had gotten the impression that for Home Theater (*not* for music) a pretty dead room was pretty desirable. Do you find that the room being dead is a problem with accurate sound reproduction during movies, or that it makes the room feel uncomfortable while not watching? Or is this a music listening room for you as well?
> 
> 
> In my case (working with bpape), I'll have dead front/rear walls (2" 703), and essentially 1" 703 up to 5' on left and right walls (full height behind the screen to 3' in front of the screen). That sounds pretty close to the room described by penngray (front covered, half-height on side walls). I'll actually have a bit more than he has (and some big bass traps in all corners).
> 
> 
> I'm not too worried about over doing it, however. All of my treatments (except for the bass traps) will be in framed panels on the walls, with the panels going floor to ceiling. I'll be able to adjust the treatment amount later if needed after measuring. I plan to go wild with the PC/sound-card/mike measurements, although I've got no idea if I'll be able to do any useful analysis...



Well, I certainly will defer to bgape's experience, but is your entire back wall treated?


I have an extremely accurate front stage and excellent mains/surrounds integration. I would say that it is due in equal parts to my acoustical treatments, the M&K S-150 THX-based speaker system and Audyssey built into my OP 885. Having said that, I'll reiterate that I want to increase the sense of envelopment from my surrounds.


There are some new studies from some well known acousticians - Toole, IIRC - who are heading in the direction of recommending completely eliminating absorbers on the sides. I'm not ready to do that, but it is interesting reading.


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/13616880
> 
> 
> It's a small room. Did I mention that it's too easy to over deaden a small room?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ...
> 
> I do not have a completely dead room, but I feel as though I need put a little air into it. Also, I'd like to increase the sense of envelopment from my side surrounds - dipoles.



Makes sense. I can see two issues:

- just walking around the room, if it sounds like one of those anechoic chambers, it might be a bit wierd.

- surround 'atmosphere'.


I hadn't been too worried about the former, but the latter makes sense. In an ideal world you'd have a totally dead room and some kind of speaker array on all sides. 256:12 sound tracks, with a fully enveloping set of speakers.


In the real world, especially with dipole side speakers not pointing at the listeners, if you have a totally dead room you'd hear very little from the sides at all. I hadn't thought about it that way...


----------



## pmeyer




> Quote:
> Originally Posted by *dbbarron* /forum/post/13616815
> 
> 
> Paul:
> 
> 
> It appears you are spending lots of time and resource on the project. Suggest you go over to hometheatershack.com and get a copy of REW (room eq wizard) and read the forums. For the cost of a calibrated mic and mic preamp (about $100 total), you can have quite an effective measuring system.
> 
> 
> db



I've been over there. At one point I downloaded the ETF demo and played with it (using my RS analog sound meter as a mic). I'll look into REQ. Analysis is on the list to do once the room is carpeted and the equipment in (or at least the room dust free).


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/13616994
> 
> 
> Well, I certainly will defer to bpape's experience, but is your entire back wall treated?



My room is 16' wide, with a 10' high ceiling. Soffit and light shelf take up two feet, so the side/back walls are 8' high.


The middle 11' of the back wall, 8' high, will be treated with 2" 703. The angled entrance area near the door won't be, and there is a closet door on the rear right that won't be. See my sig for a link to pictures that may help understand.


One problem I can see with not treating the back wall: It is a first reflection point! My rear seat ears are only 3-4' from the back wall. Back wall reflections will likely be even closer in time than side wall reflections for the back row.


We'll see how it goes.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/13617018
> 
> 
> Makes sense. I can see two issues:
> 
> - just walking around the room, if it sounds like one of those anechoic chambers, it might be a bit wierd.
> 
> - surround 'atmosphere'.
> 
> 
> I hadn't been too worried about the former, but the latter makes sense. In an ideal world you'd have a totally dead room and some kind of speaker array on all sides. 256:12 sound tracks, with a fully enveloping set of speakers.
> 
> 
> In the real world, especially with dipole side speakers not pointing at the listeners, if you have a totally dead room you'd hear very little from the sides at all. I hadn't thought about it that way...



The LEDE (live end-dead end) stuff is a holdover from 2-channel reproduction. No clear and unanimous path has been arrived at for multi-channel. I've got the dead end part down quite nicely, especially with the addition of the superchunk bass traps. As for the rest of the room, with the exception of the rear wall first reflection point absorber, I feel that what I have done is not quite right for 7.1.


Just my $.02.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/13617129
> 
> 
> One problem I can see with not treating the back wall: It is a first reflection point! My rear seat ears are only 3-4' from the back wall. Back wall reflections will likely be even closer in time than side wall reflections for the back row.
> 
> 
> We'll see how it goes.



Try treating only the exact first reflection point.


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/13617221
> 
> 
> Try treating only the exact first reflection point.



I could do that. It would be pretty much the full width, but would only need to be between 3-6' off the ground. For now I'll stick with the plan and see how it feels.


The easy thing would be to make the rear row have high back chairs. Problem solved.


----------



## pmeyer

I just realized something: I left out critical information (and am not accurately representing Bryan's plan).


The rear wall is completely covered with 2" 703 *with FSK* (aka the paper insulation cover). It will therefore act as some absorption in the middle, but not low (too thin) or high (paper). The sides and front are the same as mentioned above.


This will help: [edit: this is Bryan Pape's plan]


----------



## allredp

Paul--I'm not a technician, so I fear this will sound stupid! I'm firing away, anyway...










On your diagram, what are the yellow boxes on the very bottom that look like they are another set of L/C/R with what appear to be the reflections coming off them?


Is that just the 1st reflection pattern?


Also, how do the bass absorbers work placed directly in your double-door way?


Thanks for any insight!


Best to you,

Phil


----------



## pmeyer

I didn't mention it, but that is bpape's plan for my room, I can't take credit for it.

The 'virtual' speakers are just reflections of the front speakers through the left wall to make it easy to draw the first reflection points. If you draw speakers on the other side of the wall the same distance from the wall as the main speakers, and then draw a straight line from them to each head, the intersection with the left wall is the reflection point. Easier than trying to measure all the angles.


As for the bass trap over the door, it's shown as two, but I'm actually doing it as one:











The attic over the left wall/door is actually about 6-8 feet above the ceiling, so I have room to walk around up there. I cut back and rearranged some ceiling drywall supports up there and carved out a 2.5'x4'x2'deep bass trap in the ceiling over the door. It'll be covered with some kind of cloth panel (tbd).


----------



## penngray

Pmeyer...In your analysis, it says bass absorbers 17x17x24 from bulk Cotton.


What is bulk cotton? it can be used instead of rockwool or oc703??


----------



## pmeyer

It's normal house insulation created from recycled blue-jeans. Here's a link for a picture (this isn't the brand I got, I just googled for cotton insulation r-13)

cotton insulation 


Mine is similar to that, but thicker (about 5") and 24" wide.


The only reason Bryan marked my bass traps that way is that I've got three rolls of it lying in the garage and had a local source. It's a lot easier to work with than fiberglass. I picked up three rolls at one point. Unfortunately, my source (Eco-wise in Austin) temporarily doesn't carry it any more.


I'll probably still do my front bass-traps out of 703. My back right bass trap is big enough and deep enough that I'll probably use the cotton. Especially since I can compress it vertically and get it a bit denser in the frame back there.


I don't know what I'll do over the door. 2x4 sheets of 703 will fit up there nicely and will be easier to hold up than the floppy bulk cotton would be. If I do cotton, I'd need to build some kind of grating to keep it from coming down, and compressing it would be difficult.


----------



## eugovector

Hmm, for fabric covered walls, that acoustic cotton looks nice. No harsh fibers, similar price to 703, and good coefficients. Other than it's lack of rigidity, are there any cons I'm missing?


----------



## pmeyer

Its thickness. Look up "Bonded Logic Inc's UltraTouch Cotton" r-13 on Bob Gold's absorption site . The 3.5" thick stuff is very effective (95% down to 125 Hz), but it's 3.5" thick!


I thought about coming up some crazy 2' wide cutter to slice the 3.5" stuff into 1.75" halves and use that (slightly compressed) in a 1.5" frame, but it didn't seem worth the effort.


Interestingly, the stuff I have has a certain amount of plastic fibers (polyester? nylon?). If you compress it and heat it, the fibers melt and it retains it's new thickness/density. I thought about trying to 'densify' my cotton a bit and make it thinner. Again, I couldn't think of a practical way to do it. The acoustical properties of what I had in the end would be unknown anyway.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pmeyer* /forum/post/13628234
> 
> 
> Its thickness. Look up "Bonded Logic Inc's UltraTouch Cotton" r-13 on Bob Gold's absorption site . The 3.5" thick stuff is very effective (95% down to 125 Hz), but it's 3.5" thick!



Compare with AcoustiCotton, right above it on Bob's page. Or Echo Eliminator bonded acoustical cotton, right below it.


Regards,

Terry


----------



## penngray

pmeyer, thanks that is an interesting alternative. I have corner bass traps to fill also and I might use that instead of the more rigid Rockwool 60.


Heck its cheaper and better if you compare 3.5" vs the Rockwool 60 2".. I already spend $150 on the rockwool. I could have spend $160 (edited, shipping is $60) on this stuff and it has better numbers










I wonder why its never talked about before, I guess I just missed it.


----------



## pmeyer

You need to be careful comparing. It looks to me like 4" rockwool has about the same numbers as the 3.5" cotton. I'm betting 2 layers of 2" rockwool are the same as or better than 1 layer of 3.5" cotton.


It comes down to what you can get, what is cheap, and what is easy to work with.


----------



## penngray




> Quote:
> You need to be careful comparing. It looks to me like 4" rockwool has about the same numbers as the 3.5" cotton. I'm betting 2 layers of 2" rockwool are the same as or better than 1 layer of 3.5" cotton.
> 
> 
> It comes down to what you can get, what is cheap, and what is easy to work with.



Well to get the same sqft..I think its about the same cost for 2" vs 3.5" so that alone shows me that the UltraTouch stuff is the better buy, much better coeffecient at low frequencies.


R-13 3.5" (mm) A 0.95 1.30 1.19 1.08 1.02 1.00 1.15


vs


RXL 60 2" 0.32 0.81 1.06 1.02 0.99 1.04 0.95



I was using the Rockwool60 in the corner traps, which will have a frame just like yours. I had to cut the 2x4 rigid sheets to fill the frame. Now I can easily fill the frame with long lengths of the ultratouch, compressing it together is I add more layers. I just seems so much easier in my books.


I just purchased 106 sq ft of the stuff....I will fill one corner trap with it and another one with the Rockwool 60 I own.


Some lucky member will probably get a great deal from me, I think I have too much OC703 and too much Rockwool 60...but we shall see.


----------



## bpape

Actually, the 2" with a facing is relatively good down reasonably low.


Coefficients:


0.63 0.56 0.95 0.79 0.60 0.35


There's a bit of a hump in the middle but it's still respectable down at 125Hz and lower. Just helps in the length dimension with midbass boominess and giving some broadband control opposite the screen area without killing the highs on the back wall in the surround field.


Bryan


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13629251
> 
> 
> Some lucky member will probably get a great deal from me, I think I have too much OC703 and too much Rockwool 60...but we shall see.



Hold onto it! Properly used and placed, this is a pile of gold.










Regards,

Terry


----------



## penngray

I just was using that reflection program from this forum and it shows a reflection on the ceiling.


I dont read much about ceiling treatments. Im thinking that after everything is done, I might build a 2x4 panel and place it on my ceiling at the reflection point.




> Quote:
> Hold onto it! Properly used and placed, this is a pile of gold.



Yeah, its nice to have too much just in case. I also think my bass traps will be better now because I can go thicker with them.


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13653664
> 
> 
> I just was using that reflection program from this forum and it shows a reflection on the ceiling.
> 
> 
> I dont read much about ceiling treatments. Im thinking that after everything is done, I might build a 2x4 panel and place it on my ceiling at the reflection point.



Ceiling reflections may or may not be a problem. If you happen to be using THX front speakers, then they will probably not be. This is because the required dispersion pattern for a THX main is wide horizontally, but narrow vertically.


Regards,

Terry


----------



## ImkSpyPlns

if GOM is too expensive a fabric for me, but I don't want the farm smell of some burlap, what would be a good mid-end fabric that passes the blow test and comes in a variety of colors?


I went to JoAnn's, but it would've taken me hours to blow through every damn fabric. Plus I'd look like a complete moron blowing on every fabric!


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13654561
> 
> 
> Ceiling reflections may or may not be a problem. If you happen to be using THX front speakers, then they will probably not be. This is because the required dispersion pattern for a THX main is wide horizontally, but narrow vertically.
> 
> 
> Regards,
> 
> Terry



That is a very good point. THX-certified speakers have very tightly controlled vertical dispersion just for this very reason - reduce/eliminate ceiling (and floor) reflections. Having said that, and in line with my "I think I did too much" feeling, I did place a front ceiling absorber, which I am now considering removing (and possibly replacing with diffusion). I have THX Ultra speakers.


Pics here .


----------



## bpape




> Quote:
> Originally Posted by *ImkSpyPlns* /forum/post/13654653
> 
> 
> if GOM is too expensive a fabric for me, but I don't want the farm smell of some burlap, what would be a good mid-end fabric that passes the blow test and comes in a variety of colors?
> 
> 
> I went to JoAnn's, but it would've taken me hours to blow through every damn fabric. Plus I'd look like a complete moron blowing on every fabric!



Muslin will work well for treatment covering and is very inexpensive. It is not, however, suitable for in front of speakers. It's also not a fire rated material.


Bryan


----------



## ImkSpyPlns




> Quote:
> Originally Posted by *bpape* /forum/post/13654888
> 
> 
> Muslin will work well for treatment covering and is very inexpensive. It is not, however, suitable for in front of speakers. It's also not a fire rated material.
> 
> 
> Bryan



Thank you. It won't be in front of speakers.


BTW, appropriate that you replied, I have a order on its way from GIK as I type this. Tri-corners and some 442's. I'm finally getting around to treating my extremely small room. Of course I do it now after I spent the last few days tuning my system as best I can. When I get the treatments in, I'm sure I'll have to re-tune.


----------



## Terry Montlick

As for treating rear wall reflections from front speakers, this is often not necessary. Unless you are very near the rear wall, the reflection will not occur within the first 15 milliseconds or so of the direct sound. This means that your brain cannot merge the two sounds into a single sound with degraded spatial localization.


Also, unless you are very near the wall, any significant notch filtering due to interference between direct and reflected sound will be very low in frequency -- low enough to be absent because it has been offloaded to your subwoofer by your bass management system!


Regards,

Terry


----------



## dbbarron

Have now completed acoustic treatment prototyping.


I had a real problem with bass modes in my screen 'alcove' in the front of the room so I choose to treat the entire alcove with 4" mineral wool (covered with 1" linacoustic - cheaper than GOM)


2'x6'x4" bass traps in the rear corners; and


48" high panels of 1" linacoustic on the side walls (just cut pieces of linacoustic - have not framed them yet)


See before and after RT60 and Freq response below (note before is red, after blue)




















Please note that I have 4 subs in 1/3 2/3 positions on the front and rear walls.


Have to say the RT60 may be a bit low. I may scale back the side panels a bit.


However, the room sounds very good, albeit a bit dead. Whenever I listen in a room like this I like to say that it ruins all my recordings. I hear every error in mix, artificial reverb, MP3 (my library is in iTunes) encoding compression, etc. But when a recording is good, its great!


All comments welcome!


----------



## dbbarron

Here is some more data from the prior post. Impulse and waterfall




















On the impulse response, I have identified the first 3 large impulses as the following:


3ms - ceiling first reflection. When I temporarily placed a piece of linacoustic at this reflection point the peak decreased 10db - strategy - will treat


6-8ms - reflections from along the length of the soffit vertical portions - this section is only 8" high but is clearly causing substantial reflections - when I placed a temporary piece of linacoustic here, the reflections decreased 8db - strategy - will treat


9-10ms - side walls, already treated with 1" linacoustic -might be column edges also - likely leave be. Perhaps add another layer?


General questions


How is the performance of this room?


Once treated, are the first reflections sufficiently mitigated (per above)?


Is the RT60 too low (see prior post)?


Regards

db


----------



## Terry Montlick

db,


The only reflection that really needs treatment is the ceiling reflection at 3 ms. The other reflections are low enough not need treatment.


What are the dimensions of this room?


Regards,

Terry


----------



## dbbarron

Thanks Terry - Here is a rough sketch (dimensioned)


----------



## allredp

Hey db,


What equipment are you using to generate your measurements and graphs?


That's great news from Terry about only needing to treat your ceiling, eh?!


Have you got any pics of your room--I'd love to see your quad subs!


Keep up the great work,

Phil


----------



## Terry Montlick

Hi db,


I'd say that your reverberations times in the octave bands 125 Hz and 250 Hz are a bit too high relative to the higher frequency octave bands. These higher frequency octave band reverberation times are not too low on an absolute scale, but too low on a scale relative to the 125 Hz and 250 Hz octave bands. This unevenness can make the room sound too dead. As for the 63 Hz octave band, reverberation time measurement at these low frequencies is too unreliable in small rooms to be useful.


But since your upper frequencies are fine, you just need more absorption at the highly treatable 125 Hz and 250 Hz octave bands. I recommend either DIY bass traps, as described in this forum and on http://forum.studiotips.com/viewtopic.php?t=535 , or ready-made bass traps by forum members RealTraps or GIK Acoustics.


Regards,

Terry


----------



## allredp




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13679943
> 
> 
> As for treating rear wall reflections from front speakers, this is often not necessary. Unless you are very near the rear wall, the reflection will not occur within the first 15 milliseconds or so of the direct sound. This means that your brain cannot merge the two sounds into a single sound with degraded spatial localization.
> 
> 
> Also, unless you are very near the wall, any significant notch filtering due to interference between direct and reflected sound will be very low in frequency -- low enough to be absent because it has been offloaded to your subwoofer by your bass management system!
> 
> 
> Regards,
> 
> Terry



Terry--how close is close to the back wall? My setting is about 2ft. off the back wall.


My room is on the wide orientation (27'w x 15'd x 8'h)...


Thanks for the insight.

Phil


----------



## Ethan Winer




> Quote:
> Originally Posted by *allredp* /forum/post/13734254
> 
> 
> Terry--how close is close to the back wall? My setting is about 2ft. off the back wall.



I'm not Terry but I'll do my best.










Having a reflecting wall close behind you is a problem for two reasons. First, if the wall is less than ten feet away, reflections are considered "early" and harm imaging and clarity at mid and high frequencies. Second, the closer you are to a reflecting wall, the worse the peaks and nulls will be.



> Quote:
> My room is on the wide orientation (27'w x 15'd x 8'h)



This is why it's better to have the speakers fire the longer way down the room - it puts the wall behind you that much farther away. These two short articles explain in more detail, and prove the points with response graphs:

http://www.realtraps.com/art_room-setup.htm 
http://www.realtraps.com/rfz.htm 


--Ethan


----------



## dbbarron

Terry - I see your point from the waterfall regarding the 125 and 250Hz bands.


I'll try experimenting with the existing bass traps positioning and supplementing same.


Since my sidewalls have 1" linacoustic panels, and the 1" absorbtion parallels the issues you identify (absorbtion falls off starting at 250hz), would increasing the sidewall panels to 2" (double 1" - I have the extra material) address the issue? higher frequencies should be unaffected as the panel absorbtion is already near 100% in the upper bands- same for RT60 above 250hz.


allred: See Mayflower Construction Thread for pics - using 4 OEM10s for subs. LCRs are WCW config (Dayton reference 10"+Seas Coax).


db


----------



## Terry Montlick




> Quote:
> Originally Posted by *dbbarron* /forum/post/13734791
> 
> 
> Terry - I see your point from the waterfall regarding the 125 and 250Hz bands.
> 
> 
> I'll try experimenting with the existing bass traps positioning and supplementing same.
> 
> 
> Since my sidewalls have 1" linacoustic panels, and the 1" absorbtion parallels the issues you identify (absorbtion falls off starting at 250hz), would increasing the sidewall panels to 2" (double 1" - I have the extra material) address the issue? higher frequencies should be unaffected as the panel absorbtion is already near 100% in the upper bands- same for RT60 above 250hz.



Yes, the 2" material will help. Also, using ASJ (All Service Jacket) or FRK (Foil Reinforced Kraft) faced fiberglass will dig deeper into the low frequencies and give your room a little less in the highs. An ideal place to do this is on the upper parts of your side wall, above the positions of early reflections. You may may also use your existing fiberglass to 2 inches with a covering of ordinary Kraft paper.


Regards,

Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13734776
> 
> 
> I'm not Terry but I'll do my best.



What Ethan said.










- Terry


----------



## penngray




> Quote:
> Terry--how close is close to the back wall? My setting is about 2ft. off the back wall.
> 
> 
> My room is on the wide orientation (27'w x 15'd x 8'h)...
> 
> 
> Thanks for the insight.
> 
> Phil



My room is very, very similar....25 W x 14 d x 8 h.....one row, 2 feet off the back wall!!!


Yes, going 25 deep would be the better option but its not going to happen so what can we do???


I have read enough to believe that if I have 2" across the back wall 24 to 48 inch high that I should be able to still control the reflections.


----------



## Terry Montlick

2 feet is too close to the back wall to get away without treatment. You'll need about 4 inches of unfaced semi-rigid fiberglass or equivalent. You can also use a 2" thickness, but leave a 2" air gap to the wall.


Regards,

Terry


----------



## allredp




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13737068
> 
> 
> 2 feet is too close to the back wall to get away without treatment. You'll need about 4 inches of unfaced semi-rigid fiberglass or equivalent. You can also use a 2" thickness, but leave a 2" air gap to the wall.
> 
> 
> Regards,
> 
> Terry



OK, so I have been planning on having 1" Linacoustic from the floor up to 38" high all along the back wall in a boxed panel (in fact, it will be around the entire perimeter of the room).


Should I increase the depth of the back wall boxed panel to accomodate some 3" mineral wool or spinglass that I have? Will that work?


I'm assuming that the 4" panel you are describing is meant to be mounted on the wall centered at ear height and most of the length wide.


In my case, WAF will not allow that ideal location of a panel for me, so I'm looking at options!


Big time thanks for the help!


Phil


----------



## penngray




> Quote:
> 2 feet is too close to the back wall to get away without treatment. You'll need about 4 inches of unfaced semi-rigid fiberglass or equivalent. You can also use a 2" thickness, but leave a 2" air gap to the wall.



wow, I didnt expect it too be that bad, thats going to be hard to do







Maybe a 4" thick, 2x8 panel behind of the row is what I might be able to design. Frame it and mount it...it will look a little out of place but if it helps I could try it.



Is it because low frequences are bouncing off the wall too?


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13738335
> 
> 
> wow, I didnt expect it too be that bad, thats going to be hard to do
> 
> 
> 
> 
> 
> 
> 
> Maybe a 4" thick, 2x8 panel behind of the row is what I might be able to design. Frame it and mount it...it will look a little out of place but if it helps I could try it.
> 
> 
> 
> Is it because low frequences are bouncing off the wall too?



Yes. At only a 2 foot distance, I'd expect you'd have a strong interfering reflection at about 141 Hz. This is because 141 Hz sound will be out of phase by 180 degrees after it travels a total distance of 4 feet. This is assuming incident angle reflection. So the reflection from mains will be a little farther, hence a bit lower in frequency.


This is likely to create a nice notch in your frequency response.







This isn't the end of the world by any means, but if you have the opportunity to eliminate it from the start, it is a good idea. It will also fix strong early reflections which would be observed at higher frequencies. That's the reason I am recommending a wideband absorber (unfaced fiberglass), and not a membrane bass trap. And if this was your second row back, rather than your only seating row, I'd worry less about it because you'd still have a row of "prime" seats.


I'd also use a 4'x8' panel, since the wavelength is rather large and would therefore involve a larger area of wall for reflection.


Regards,

Terry


----------



## penngray




> Quote:
> This isn't the end of the world by any means, but if you have the opportunity to eliminate it from the start, it is a good idea.



I will build the 4'x8' 4" thick panel, thanks!


----------



## penngray




> Quote:
> I will build the 4'x8' 4" thick panel, thanks!



Just reading more about diffusors, would a 4x8 diffusor be an alternative?


----------



## Ethan Winer




> Quote:
> Originally Posted by *penngray* /forum/post/13739617
> 
> 
> Just reading more about diffusors, would a 4x8 diffusor be an alternative?



Diffusors are good on a rear wall, but not so good if you're only a few feet away from that wall. Moreover, most diffusors do little below about 1 KHz (depends on their depth), but peaks and nulls extend down to the bass range. See Terry's example of 2 feet giving a deep null at 141 Hz. There's also a peak at 282 Hz, another deep null at 424 Hz, and so forth. These low frequency peaks and nulls are not avoided with typical diffusors.


This page explains a frequency / distance calculator program you can download for free:

http://www.realtraps.com/sbirlbir.htm 


--Ethan


----------



## krasmuzik

Below 500Hz wall reflections are already diffuse - most "bass diffusers" on the market are in fact treble diffusers that provide bass absorption...because a real bass diffuser capable of disrupting modal and SBIR behavior is too huge to ship especially when it is best built into the room. The problem is the bass reflection even though spatially diffuse (spread to all angles but reduced in level) - still causes the frequency notches because it is not time diffused - but since you likely need bass absorption there are simpler ways to solve the problem.


I'l leave the shameless plugs for the experts in that dept....but a treble diffuser with bass absorption will do good for backwall reflections - but so will a broadband absorber (thicker fiberglass/rockwool panel).


You need to know if you have enough treble absorption already and if that spot is better to be treble diffused (with bass absorb) or treble absorbed (broadband bass trap) or treble reflected (bass only panel/membrane trap).


----------



## daxhughes

I am setting up my theater room using the following:


Pioneer Kuro 60 inch plasma 150fd

B&W 804s for fronts

HTM3S center

Ds8 dipolar rears

Sunfire Signature EQ sub

ND preamp and amp



I want to get the best sound possible. I will sit 10' from the monitor so that i am equal with the distance from my fronts from one another. I am trying to create as close to an equalateral triangle as possible.


!) QUESTION- That will put my fronts around 1' from the side walls. Is that enough? They will be around 2 1//2' from front wall.


2) Because I am only sitting 10' from monitor I will be 13' ft from my back wall. That seems pretty far away from the rear wall.


a) Is that an acoustic issue? Does it help or hurt being so far away?

b) What kind of acoustic treatment should I use on the back wall- absorbant shields or dissonance or none?


3) I want to do a good job with acoustic shielding.


a) I am thinking a shield on the front wall behind each front speaker (excluding center).

b) First reflection points on side wall using mirror trick.


1) Should i do ceiling first reflection point (flat drywall)?

2) I have carpet on the floor.


c) What thickness should I use on the absorbant shields 1" or 2"?


d) How important are bass traps and where should I put them in the top 4 corners or just the middle of the four corners?



THANKS FOR THE ADVICE!!!!!!!!!!!!!!!!!!


----------



## allredp

Dang--unlike penngray, I can't do a hanging panel just behind my seating on the rear wall.










So, considering my same wide-room/close-to-the-back-wall problem, WAF will let me have a built-in boxed-panel trim with GOM-covered 1" Linacoustic either from floor up to 38" or from ceiling down to 38". Above or below that I'm stuck with plain painted walls.


Which should I do?


Is is better to have the absorption above the ear-level all around, or below the ear-level all around?










I get one or the other, and WAF will not allow for individualized panels on the walls.


BTW, for bass-trapping I will have columns flanking my screen that I'll fill from the top of the L/R speakers to the ceiling with rockwool chunks, and I will have two columns on the back wall also filled with chunked rockwool.


So, which should I do? Whole-room treatment above or below 38"?


Any help completely appreciated!!!










Thanks,

Phil


----------



## penngray




> Quote:
> So, considering my same wide-room/close-to-the-back-wall problem, WAF will let me have a built-in boxed-panel trim with GOM-covered 1" Linacoustic either from floor up to 38" or from ceiling down to 38". Above or below that I'm stuck with plain painted walls.
> 
> 
> Which should I do?



You can not make the bottom half of your back wall 4" thick? place a shelf (maybe 6" deep) on it to blend it better with the top half. I would look just like a wall then?


----------



## cuzed2

Question(s) for the acoustic experts that are lurking...


The sketch below is the layout of my theater area. As you can see I have compromised in order to have a somewhat open floor plan, leaving an open game area to the left of the theater area.










I have since boxed in the areas (in red) to the LH and RH side of the screen, in the sketch below, this was done to hide utilities in the front RH corner, and (on the left) to keep things symmetrical.










The actual photo below is where I am today.









I will be adding floor to ceiling bass traps (OC703) in the front corners, and I will be insulating the studs with pink stuff between the studs on the screen wall, and plan to cover the front wall with linacoustic and GOM.


My question: should I also treat the sidewalls immediatly adjacent to the LH and RH side of the screen?


Other info and questions:


The finished ceiling height will be 7'9", the ceiling joists will be stuffed with insulation, and then using the ceiling max system will be finished with acoustical tile.


I am planning on stuffing the soffits with pink stuff, then drywalling the underside and vertical surface of the soffits - Is this a mistake?


I will try to hit the reflection points with panels (at least the RH side). Should I treat the back wall? Would there be any benefit to putting corner traps in the upper rear corners instead? How about corner traps in the upper corenrs of the adjoining game room area?


Thanks in Advance!


----------



## affeking

OK, I'm in the final stretch in designing my first crack at room treatments. I have a couple of questions related to absorbers that I haven't seen clearly answered.


1) I'm going to build superchunks for all corners that are avail (back right leads to a hallway so no corner there). I am going to build them floor to ceiling, inside a frame for portability and built-in air gap. My question is actually about the size...I've heard people build them with the outer edge being 2' and some doing 2.8' (the difference between cutting 2x4 panels into 8th or 4ths). I was hoping to get by with the 2' outter edge, but I don't have a clear understanding of the performance difference. Anyone have charts showing this possibly?



2) In the back of the room, I am planning to build some bass abosption panels to mount behind the seating area. These will be 4" thick and have a 1.5" air gap between the wall and panel. So we are talking an almost 6" protrusion. Isn't this going to look pretty ugly? How are people doing these thicker panels that makes them look a little less odd?


Thanks,

Affe


----------



## penngray

Is there a good guide on how to use REW for doing room sound analysis?


I have my carpet and the chairs in, Im going to hook up all my equipment and run tests before I put up acoustical material.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13755258
> 
> 
> Is there a good guide on how to use REW for doing room sound analysis?
> 
> 
> I have my carpet and the chairs in, Im going to hook up all my equipment and run tests before I put up acoustical material.



Been to this page ? You'll need to register at the Home Theater Shack Forum to get the latest files. There are also help files there, plus links to the forum threads themselves devoted to the software.


My home theater website has now been updated with the whole story of the recently installed chunk traps. Check my sig.


- Jeff


----------



## penngray

Thanks! Also, thats a great link...the turkey carver is what I should have used for cutting all my insulation!! What a great tool!


----------



## nathan_h

Should bass trapping be symmetrical? I can add a couple of bass traps along the right side wall/ceiling connection -- but cannot put them on the left side. Should I do it anyway, or will I create something weird? (I know for mid/high freq absorption symmetry is important.)


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/13758530
> 
> 
> Should bass trapping be symmetrical? I can add a couple of bass traps along the right side wall/ceiling connection -- but cannot put them on the left side. Should I do it anyway, or will I create something weird? (I know for mid/high freq absorption symmetry is important.)



Bass trapping does not need to be symmetrical. I have just added some in the front left corner, the front right corner and the front top corner. (See sig.) It has made an INCREDIBLE difference. True, mine is symmetrical with respect to the front L&R, but there is no symmetry from the front to the rear.


- Jeff


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13755700
> 
> 
> Thanks! Also, thats a great link...the turkey carver is what I should have used for cutting all my insulation!! What a great tool!



Thanks.


I seem to have forgotten to link the 3rd page of the bass trap installation . . . try this .


----------



## allredp




> Quote:
> Originally Posted by *penngray* /forum/post/13745684
> 
> 
> You can not make the bottom half of your back wall 4" thick? place a shelf (maybe 6" deep) on it to blend it better with the top half. I would look just like a wall then?



Great point, penngray. I think I might be able to work that after all!







I will be doing 1" linacoustic all around the room anyway, it wouldn't look too different with a thicker version of the same panel boxes I'd imagine. We'll see what the WAF does with that, eh?!


If I did do this, it would make a 4" thick mineral wool or spin-glass (unfaced) GOM covered absorber about 16' long across the back wall from floor to 38"H. Is this too much, or just right to mitigate the seating position being only 2.5' off the rear wall?


Also, which would be better, the spinglass (JM 3" yellow stuff) or mineral wool (JM 3" dark green/brown stuff)? And I'm assuming I would put a 1" space between the 3" stuff and the wall to make my 4" total?


The help is hugely appreciated!


I'm dying to get installing things (my new Dali speakers arrived this week, to compliment my Ultra 13







)


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/13761877
> 
> 
> Thanks.
> 
> 
> I seem to have forgotten to link the 3rd page of the bass trap installation . . . try this .



Hey pepar,


How'd you cut your chunks so uniformly?!


I've used the electric meat cutter knife, but haven't had such nice clean cuts as you...










Any tips for a dummy?


----------



## yngdiego




> Quote:
> Originally Posted by *allredp* /forum/post/13765448
> 
> 
> Hey pepar,
> 
> 
> How'd you cut your chunks so uniformly?!
> 
> 
> I've used the electric meat cutter knife, but haven't had such nice clean cuts as you...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Any tips for a dummy?



Yours probably look like mine then, lol!







I used a turkey carver as well. I did draw lines with a heavy marker to follow, but freehanded the actual cut for all the triangles.


Now when I cut two panels in half for 1'x4' panels I did rig up vice of sorts on the edge of my workbench so my saw would follow a perfectly straight line. Those cuts did come out nearly perfectly. I could have done the same for all the triangles, but since they would be hidden behind fabric I didn't want to take the extra time to do it.


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/13765448
> 
> 
> Hey pepar,
> 
> 
> How'd you cut your chunks so uniformly?!
> 
> 
> I've used the electric meat cutter knife, but haven't had such nice clean cuts as you...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Any tips for a dummy?



Turkey Carvers for Home Theater Dummies?










I used a metal straight-edge to first cut a shallow line and then endeavored to keep the blade(s) vertical as I completed the cut through the piece. It was not easy and my wrist was aching by the end of the cutting session.


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/13766255
> 
> 
> Turkey Carvers for Home Theater Dummies?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I used a metal straight-edge to first cut a shallow line and then endeavored to keep the blade(s) vertical as I completed the cut through the piece. It was not easy and my wrist was aching by the end of the cutting session.



Just what I figured--your excellence was not due to superior technology which I might also get my hands on, but hard, careful, time-consuming, painful, old-fashioned effort--dang...


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/13761794
> 
> 
> Bass trapping does not need to be symmetrical. I have just added some in the front left corner, the front right corner and the front top corner. (See sig.) It has made an INCREDIBLE difference. True, mine is symmetrical with respect to the front L&R, but there is no symmetry from the front to the rear.
> 
> 
> - Jeff



Thanks for the feedback. Mine is symmetrical side to side, but not front to back -- where I have trapping along the front floor/wall connection but in the rear it is across the places where the back wall meets the left wall and where the back wall meets the right wall.


I don't know why I was thinking left right matter more than front back in terms of symmetry -- probably getting confused about the nature of bass.


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/13766592
> 
> 
> Just what I figured--your excellence was not due to superior technology which I might also get my hands on, but hard, careful, time-consuming, painful, old-fashioned effort--dang...



Yea, there was no "easy" button for this task. I might also mention that one of these is an absolute must when working with insulation:


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/13769079
> 
> 
> Yea, there was no "easy" button for this task. I might also mention that one of these is an absolute must when working with insulation:



Got it! I'm a firm believer also--I get a cold or headache or both every time otherwise.


Any breakthroughs on livening-up your room?


----------



## allredp




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13738690
> 
> 
> Yes. At only a 2 foot distance, I'd expect you'd have a strong interfering reflection at about 141 Hz. This is because 141 Hz sound will be out of phase by 180 degrees after it travels a total distance of 4 feet. This is assuming incident angle reflection. So the reflection from mains will be a little farther, hence a bit lower in frequency.
> 
> 
> This is likely to create a nice notch in your frequency response.
> 
> 
> 
> 
> 
> 
> 
> This isn't the end of the world by any means, but if you have the opportunity to eliminate it from the start, it is a good idea. It will also fix strong early reflections which would be observed at higher frequencies. That's the reason I am recommending a wideband absorber (unfaced fiberglass), and not a membrane bass trap. And if this was your second row back, rather than your only seating row, I'd worry less about it because you'd still have a row of "prime" seats.
> 
> 
> I'd also use a 4'x8' panel, since the wavelength is rather large and would therefore involve a larger area of wall for reflection.
> 
> 
> Regards,
> 
> Terry



Great help, Terry and Ethan!
























One question--if I make my 4" unfaced spinglass or mineral wool panel (3" material with 1" gap) across the back wall 9'W x 38"H can it be from floor up to 38" and still be effective?


I'm trying to avoid placing this mid-wall which will be too high for my WAF.


Is the key simply the _amount_ of area on the wall covered, or is it also important about _where_ on the wall that area is covered for my back wall?


----------



## bpape

Having it up higher would give better performance stopping potential bass cancellations off the rear wall. If that's not an option, then I'd recommend something thicker and more of a 'chunk style' absorber behind the furniture catching the wall/floor intersection. This will control some of the boominess but won't do much for reflections off the rear.


Bryan


----------



## Ethan Winer




> Quote:
> Originally Posted by *allredp* /forum/post/13770504
> 
> 
> Is the key simply the _amount_ of area on the wall covered, or is it also important about _where_ on the wall that area is covered for my back wall?



Both.


----------



## percept

Im converting a tiny spare room into a theater, and due to its size i would imagine it needs a ton of treatment. The room is 13' L x 7.25' wide x 8' H. Seating will be about 10 ft. from the front wall, which makes that about 3 ft. from the back wall. I'll be treating the obvious first reflection points as well as the entire front wall that isn't covered by the screen (which will stretch from wall to wall).


I have a few questions:


1. How should i deal with bass trapping? corner traps dont seem possible as the screen stretches from wall to wall on the front wall, the door is located on the rear right corner and a window the rear left corner. I'll be covering that window, but prefer not to place a bass trap in that corner for aesthetic reasons (unless absolutely necessary).


2. How should i treat the back wall? Same as penngray with the 4" panel? How large of a panel?



Any help is greatly appreciated, thanks in advance for the help.


----------



## pepar




> Quote:
> Originally Posted by *percept* /forum/post/13773896
> 
> 
> Im converting a tiny spare room into a theater, and due to its size i would imagine it needs a ton of treatment. The room is 13' L x 7.25' wide x 8' H. Seating will be about 10 ft. from the front wall, which makes that about 3 ft. from the back wall. I'll be treating the obvious first reflection points as well as the entire front wall that isn't covered by the screen (which will stretch from wall to wall).
> 
> 
> I have a few questions:
> 
> 
> 1. How should i deal with bass trapping? corner traps dont seem possible as the screen stretches from wall to wall on the front wall, the door is located on the rear right corner and a window the rear left corner. I'll be covering that window, but prefer not to place a bass trap in that corner for aesthetic reasons (unless absolutely necessary).
> 
> 
> 2. How should i treat the back wall? Same ass penngray with the 4" panel? How large of a panel?
> 
> 
> 
> Any help is greatly appreciated, thanks in advance for the help.



Many times overlooked, there are "corners" formed by walls and the ceiling and walls and the floor.


----------



## affeking

OK...here is my plan for my currently untreated basement home theater. Please let me know if I'm going terribly wrong somewhere. This is just my starter package, and I think I'm hitting the most important points with this.


1) *Superchunk bass traps* floor to ceiling in the 3 corners (there is a hallway in what would be the fourth). I will be using OC703 cut into 8 triangles per 2X4 sheet for a 2' face.


I have yet to see a plan exactly like this, but my idea is to build a complete frame for these. I would put a triangle of plywood on the top and the bottom (perhaps one in the middle as well) connected by 1"X0.5" risers in the 3 corners. I will then cover it with muslin or speaker fabric. My intention with this design is to a) allow a 1" air gap between wall and fiberglass and b) allow me to easily move the traps when necessary. And it will be necessary as one will partially block a closet door.


2) *Broadband absorbers* at the first reflection points of the side walls. These will be 2" of unfaced OC703 seperated from the wall by about 1.5" and covered in muslin or speaker fabric. This will be based on the design found here: http://www.youtube.com/watch?v=iyYUpkpL0gw 

I may add more of these at 2nd reflections, but for now this is it.


3) *Panel bass traps* on the rear wall direclty behind the listeners. My seating is about 5' from the back wall. For these, I'm thinking of going with Ethan's design found here: http://www.ethanwiner.com/BTPlans.gif 

I would go for the 1/4" plywood to capture the deep bass. I was also thinking of making these ticker - 4" deep fiber with the assumption that it would increase the absorbsion. Does this sound right?


So that's it I believe. Please let me know where / how I should modify the overall plan or design of any specific pieces. I'm really uncertain on the panel traps I plan to put in the back. I'm also tempted to just go with a design similar to the broadband traps I mentioned in #2 but with FRK backing on the front of the panel and of course the ticker fiber. Thoughts?


Thanks,

Jeff


----------



## Terry Montlick

Hi Jeff,


These panel bass traps on the back wall are not a good idea in your situation. For one thing, the first and strongest frequency of the phase cancellation due to the reflected wave at a 5 foot distance is about 56 Hz, and such traps will have little effect at this low a frequency.


And a panel trap will reflect mid to high frequencies, and therefore not help with early reflections, which occur at these frequencies. I should add the caveat that rear early reflections are *less* of an issue than side reflections, as the former tend to create less spatial confusion because they are so different in direction. But for most accurate reproduction, they should be eliminated.


Acoustic control tools like panel traps are great, but they must be used under appropriate circumstances. Don't use a hammer when a screwdriver is the correct tool! Or perhaps the better analogy is a medical one, since acoustical design and treatment have their complexities. During surgery, don't use forceps when a retractor is the right tool!










Regards,

Terry


----------



## Franin




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13777270
> 
> 
> Hi Jeff,
> 
> 
> These panel bass traps on the back wall are not a good idea in your situation. For one thing, the first and strongest frequency of the phase cancellation due to the reflected wave at a 5 foot distance is about 56 Hz, and such traps will have little effect at this low a frequency.
> 
> 
> And a panel trap will reflect mid to high frequencies, and therefore not help with early reflections, which occur at these frequencies. I should add the caveat that rear early reflections are *less* of an issue than side reflections, as the former tend to create less spatial confusion because they are so different in direction. But for most accurate reproduction, they should be eliminated.
> 
> 
> Acoustic control tools like panel traps are great, but they must be used under appropriate circumstances. Don't use a hammer when a screwdriver is the correct tool! Or perhaps the better analogy is a medical one, since acoustical design and treatment have their complexities. During surgery, don't use forceps when a retractor is the right tool!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards,
> 
> Terry



Hi Terry out of curiosity do you do manual calibrations? There are many that believe in just do audyssey and your done.MY HAA calibrator ordered my room treatments the other day and he uses Sencore units to measure the room peaks and dips.Whats your thoughts on Audyssey?


----------



## ImkSpyPlns

Glenn from GIK acoustics asked me to write something up about how to install Tri-Traps in upper corners when I did mine, because he gets asked how all the time. He simply didn't have any pictures to explain how to do it. Anyway, I made a separate thread on this. Hopefully this forum was the best place for it.

http://www.avsforum.com/avs-vb/showthread.php?t=1025325


----------



## Ethan Winer




> Quote:
> Originally Posted by *affeking* /forum/post/13776160
> 
> 
> This will be based on the Joel DuBay (Realtraps) design found here: http://www.youtube.com/watch?v=iyYUpkpL0gw


*Please - No!!!!!!!!*


RealTraps is an ethical company that sells high quality products for a fair price. My company has nothing to do with that video, which is a rip-off of the design of another ethical treatment vendor. Joel DuBay has _nothing_ to do with my company, and naming his own company so close to mine is yet another rip-off that has caused such confusion more than once.


I know you didn't mean to confuse the companies intentionally Jeff, but this is a very sensitive issue for me because of all the slimy behavior over many years by said individual above.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Franin* /forum/post/13777472
> 
> 
> Hi Terry out of curiosity do you do manual calibrations? There are many that believe in just do audyssey and your done.MY HAA calibrator ordered my room treatments the other day and he uses Sencore units to measure the room peaks and dips.Whats your thoughts on Audyssey?



Yes, I do manual calibrations. But after room treatment is done. And measurement/calibration may point out the need for further room treatment.


As for Audyssey, I am doing an Audyssey MultEQ Pro calibration next week! In general, I am very impressed with this EQ technology. I've read the journal papers by its developers, Sunil Bharitkar and his Ph.D. advisor, Chris Kyriakakis. I have a reasonably good understanding of the theory behind it. Chris, BTW, is very present on the Official Audyssey Forum here, and is *the* source for practical info on Audyssey.


Audyssey doesn't replace acoustic treatment, but it fine tunes it.


Regards,

Terry


----------



## Franin




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13778586
> 
> 
> Yes, I do manual calibrations. But after room treatment is done. And measurement/calibration may point out the need for further room treatment.
> 
> 
> As for Audyssey, I am doing an Audyssey MultEQ Pro calibration next week! In general, I am very impressed with this EQ technology. I've read the journal papers by its developers, Sunil Bharitkar and his Ph.D. advisor, Chris Kyriakakis. I have a reasonably good understanding of the theory behind it. Chris, BTW, is very present on the Official Audyssey Forum here, and is *the* source for practical info on Audyssey.
> 
> 
> Audyssey doesn't replace acoustic treatment, but it fine tunes it.
> 
> 
> Regards,
> 
> Terry



Thankyou for your reply.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Franin* /forum/post/13779412
> 
> 
> Thankyou for your reply.



You're very welcome, Franin. I travel to do calibrations. Could come to Perth, mate. With plane ticket, it would be an expensive calibration.







But not the most expensive I have done!

















Regards,

Terry


----------



## Franin




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13779550
> 
> 
> You're very welcome, Franin. I travel to do calibrations. Could come to Perth, mate. With plane ticket, it would be an expensive calibration.
> 
> 
> 
> 
> 
> 
> 
> But not the most expensive I have done!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards,
> 
> Terry



He he I could see my wife getting upset, she would prefer a plane ticket to Europe.









I have a HAA calibrator at the moment doing mine Terry.He uses sencore.We'e ordered room treatment and looking forward to hear the end results.I have to say there is not many people that know about manual calibrations, they all think put the mic on that is supplied with the unit and you have the perfect sound(far from it, I reckon).if anything you guys are top when it comes to HT, because after you guys are finished I've never heard my subs sound so smooth and tight everthing was perfect.


----------



## affeking




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13778568
> 
> 
> Joel DuBay has _nothing_ to do with my company, and naming his own company so close to mine is yet another rip-off that has caused such confusion more than once.



Sorry Ethan - I changed my post to remove that info. I usually don't trust something I see in a youtube vid, but I wasn't expecting someone to misrepresent their affiliation with your company.



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/0
> 
> 
> And a panel trap will reflect mid to high frequencies, and therefore not help with early reflections, which occur at these frequencies.



Thanks for the correction Terry. Any suggestions on what I use for the first reflections instead? And I went for the traps on the back wall with the thought of 'the more bass traps the better' and I'd heard it was important to treat them behind the listening spot. Any alternate suggestions??


Thanks...

Jeff


----------



## pepar




> Quote:
> Originally Posted by *affeking* /forum/post/13781543
> 
> 
> SAny suggestions on what I use for the first reflections instead? And I went for the traps on the back wall with the thought of 'the more bass traps the better' and I'd heard it was important to treat them behind the listening spot. Any alternate suggestions??



Most of us use - successfully - 2" Owens Corning 703. Some use 4", but that can become an aesthetic issue and still doesn't reach into bass trap absorption frequencies. 1" is, IMO, too thin to be considered broadband absorption.


Just my $.02.


----------



## affeking




> Quote:
> Originally Posted by *pepar* /forum/post/13781690
> 
> 
> Most of us use - successfully - 2" Owens Corning 703. Some use 4", but that can become an aesthetic issue and still doesn't reach into bass trap absorption frequencies. 1" is, IMO, too thin to be considered broadband absorption.



Thanks pepar. It sounds like we are on the same page. I was trying to figure out what Terry was telling me and I realized I may have used the wrong terminology in my original post. Does 'panel trap' imply the use of a membrane such as plywood with absorbsion material behind it? As I tried to describe, I was just planning on tossing up a 2" thick piece of OC703 with a 1" air gap behind it. I said panel because its a flat object.


With this clarification, does this sound correct for a broadband first reflection absorber? What is the appropriate terminology for this type of....ummm...panel?


Thanks,

Jeff


----------



## percept

What purpose does the air gap between the panel and wall serve? I'd like to build some panels with as little depth as possible.


Sorry for the newb question, and thanks in advance for the response.


----------



## pmeyer

In general, air does not move at the wall. Standing waves 'vibrate' such that the air at the wall has no motion, and the air moves more and more (towards and away from the wall) as you move further from the wall, until you hit the 'peak' (1/4 wavelength of the frequency of sound you are talking about).


Therefore, the maximum air movement for any given frequency is at 1/4 of the wavelength off the wall.


The panels are designed to 'slow down' this movement. They are more effective the faster the air is moving (they can't slow down air that isn't moving right at the wall).


A thick panel solves this because the outer part of the panel is pretty far from the wall and slows down the air most effectively near the outer surface. The part of the panel near the wall isn't as effective as the air isn't moving much there.


You can make a panel more effective at lower frequencies (1/4 wavelength is bigger) if you move the panel a few inches off the wall where the air is moving more...


paul


----------



## yngdiego




> Quote:
> Originally Posted by *pmeyer* /forum/post/13783368
> 
> 
> In general, air does not move at the wall. Standing waves 'vibrate' such that the air at the wall has no motion, and the air moves more and more (towards and away from the wall) as you move further from the wall, until you hit the 'peak' (1/4 wavelength of the frequency of sound you are talking about).
> 
> 
> Therefore, the maximum air movement for any given frequency is at 1/4 of the wavelength off the wall.
> 
> 
> The panels are designed to 'slow down' this movement. They are more effective the faster the air is moving (they can't slow down air that isn't moving right at the wall).
> 
> 
> A thick panel solves this because the outer part of the panel is pretty far from the wall and slows down the air most effectively near the outer surface. The part of the panel near the wall isn't as effective as the air isn't moving much there.
> 
> 
> You can make a panel more effective at lower frequencies (1/4 wavelength is bigger) if you move the panel a few inches off the wall where the air is moving more...
> 
> 
> paul



So would 4" of OC703 right next to the wall be better or worse than a 2" panel 2" out from the wall for first reflection points?


----------



## pmeyer




> Quote:
> Originally Posted by *yngdiego* /forum/post/13783564
> 
> 
> So would 4" of OC703 right next to the wall be better or worse than a 2" panel 2" out from the wall for first reflection points?



I'll defer to the experts, but my take:


First reflection point treatment is generally about making sure that your ears correctly identify the location of sounds coming from the front speakers. Mid to high frequency sounds travel (generally) in straight lines and bounce off of things like rays of light. The direct sound and the first reflection sound off the side wall hit your ear around the same time and muddle the direction the sound came from.


The important point in the above is "mid-to-high frequency sound". Low frequency sound generally does not travel in such nice light ray paths, and isn't easy to localize (hence your subwoofer can be shoved anywhere in the room and it doesn't make you think all the bass is coming from that direction).


Therefore: first reflection point treatment is about mid-high frequencies. 1-2" of treatment is plenty for that.


For bass traps, filling a separate treatment function, you want to absorb very low frequencies (as low as you can go). Thicker treatment or treatment spaced off of the wall help with this.


Those are sort of the two ends of the spectrum: thin mid-high absorption for FRP, thick low frequency absorption for bass traps.


The other treatment often done is 'broadband absorption', 2-4" thick stuff that is trying to knock down the rt60 (echo decay time) of the room as evenly as possible across the frequencies. It's not uncommon to see thicker than 1" at first reflection points, but in general it's not because the first reflection points need it, it's because it works just fine to knock down the first reflection and is also a bit more effective at evenly absorbing lower frequencies. Two birds with one stone.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/13783368
> 
> 
> In general, air does not move at the wall. Standing waves 'vibrate' such that the air at the wall has no motion, and the air moves more and more (towards and away from the wall) as you move further from the wall, until you hit the 'peak' (1/4 wavelength of the frequency of sound you are talking about).
> 
> 
> Therefore, the maximum air movement for any given frequency is at 1/4 of the wavelength off the wall.
> 
> 
> The panels are designed to 'slow down' this movement. They are more effective the faster the air is moving (they can't slow down air that isn't moving right at the wall).
> 
> 
> A thick panel solves this because the outer part of the panel is pretty far from the wall and slows down the air most effectively near the outer surface. The part of the panel near the wall isn't as effective as the air isn't moving much there.
> 
> 
> You can make a panel more effective at lower frequencies (1/4 wavelength is bigger) if you move the panel a few inches off the wall where the air is moving more...



Paul, I was under the impression that absorbers were most effective at bass frequencies the _closer_ they are to the wall _because_ the air is moving more slowly and the waves are _easier_ to impede. Standing a panel off the wall produces a diaphramatic effect that extends the absorption to lower frequencies, but more than an inch of standoff, though, and the effectiveness because of the first point lessens.


-Jeff


----------



## pepar




> Quote:
> Originally Posted by *affeking* /forum/post/13781761
> 
> 
> Thanks pepar. It sounds like we are on the same page. I was trying to figure out what Terry was telling me and I realized I may have used the wrong terminology in my original post. Does 'panel trap' imply the use of a membrane such as plywood with absorbsion material behind it? As I tried to describe, I was just planning on tossing up a 2" thick piece of OC703 with a 1" air gap behind it. I said panel because its a flat object.
> 
> 
> With this clarification, does this sound correct for a broadband first reflection absorber? What is the appropriate terminology for this type of....ummm...panel?
> 
> 
> Thanks,
> 
> Jeff



To me, "trap" means bass trap. The panels you mention I would call broadband absorbers. "Broadband" may seem to imply _all_ frequencies, but not in acoustical treatment parlance. Corner bass traps are still required to reach the lowest frequencies. A 1" standoff can lower the lowest effective frequency of a panel through a diaphram effect, i.e. instead of absorbing from impeding the vibration of the air molecules, it absorbs by vibrating as a panel.


FWIW, I did not want my panels encroaching into my room any more so they are tight against the wall. Besides, I have bass traps for the bottom frequencies. And absorbers in the corners are much more effective at lower frequencies than panels, stood off or not, mounted on a wall.


- Jeff


----------



## affeking




> Quote:
> Originally Posted by *pepar* /forum/post/13784331
> 
> 
> FWIW, I did not want my panels encroaching into my room any more so they are tight against the wall. Besides, I have bass traps for the bottom frequencies. And absorbers in the corners are much more effective at lower frequencies than panels, stood off or not, mounted on a wall.



OK, I'm feeling a lot more confident about this after reading your posts. Might be we are in synch sharing the same name and all










Based on what you are saying, I think I will build my broadband absorbers with the lowest profile frame as possible, to minimize the airgap and focus on the mid-high frequencies. These will be 2" for the same reason.


For the LF, I will be counting on those superchunk traps. I'm still not postive this is the best route to go, but I think I will space those about 1" to increase the distance of the outside of the trap and thus get down to some lower frequencies.


At this point, I'm not sure what I'm going to do on that back wall, if anything.


BTW - love the step by steps on your site - very helpful.


Thanks,

Jeff


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/13784172
> 
> 
> Paul, I was under the impression that absorbers were most effective at bass frequencies the _closer_ they are to the wall _because_ the air is moving more slowly and the waves are _easier_ to impede. Standing a panel off the wall produces a diaphramatic effect that extends the absorption to lower frequencies, but more than an inch of standoff, though, and the effectiveness because of the first point lessens.
> 
> 
> -Jeff



Paul gave some excellent answers. For a wave which hits the wall at a normal angle, the wave velocity is highest at the 1/4 wavelength distance from the wall. It is zero right at the wall because the rigid wall prevents the air from moving.


Now, there is a significant difference between a bass absorber with and without a diaphragm on its front surface. A diaphragm is anything from a thin membrane, like a facing of FRK, to a panel of plywood.


Staying for the moment with a non-diaphragm bass trap, one whose surface is a porous absorber like the rest of it, this is a *velocity* type absorber. Air has to physically move between the open pores of the absorber for the absorber to work. And without velocity, there is no air movement.


So for a pure porous bass absorber, the deeper the better (in general), and the farther from the wall the better for low frequencies.


A diaphragmatic absorber is a more complicated beast. This is a *pressure* type absorber, and pressure is greatest right at the wall surface! But this type of absorber also requires depth, because once the diaphragm translates pressure into velocity, you are back to a porous absorber which needs depth to absorb low frequencies.


Hope this helps.


Regards,

Terry


----------



## suffolk112000

This question may have been asked several times in this thread already, but I have not been able to find the answer with searching.










I want to treat the first reflection point for my center channel. I know rule of thumb is you need at least two inches thick of an adequate treatment material to do an adequate job.

I have some leftover knauf that is 1” thick from my theater build a few years ago. Can I just double up two pieces of knauf and get the same performance as 1 panel of 2” OC 703 or 705 that is always recommended?

Or should I just buy some 705 and use that?

Another slightly off topic question. For those that have used 703 and 705, it seems like the lighter yellowish color of the insulation would show through black GOM. Especially when light hits it. My center is VERY close to the ceiling. Because I will have to put the panel somewhat close to the screen. This is a big concern for me.


Thanks in advance.


----------



## Terry Montlick




> Quote:
> Originally Posted by *suffolk112000* /forum/post/13785308
> 
> 
> This question may have been asked several times in this thread already, but I have not been able to find the answer with searching.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I want to treat the first reflection point for my center channel. I know rule of thumb is you need at least two inches thick of an adequate treatment material to do an adequate job.



I don't know where this "rule of thumb" came from, but you need only 1" of efficient absorber, like semi-rigid fiberglass, to specifically treat early reflections.


Regards,

Terry


----------



## suffolk112000




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13785360
> 
> 
> I don't know where this "rule of thumb" came from, but you need only 1" of efficient absorber, like semi-rigid fiberglass, to specifically treat early reflections.
> 
> 
> Regards,
> 
> Terry




Well thank you Terry.







Ask and yea shall receive a prompt answer.









Well, I have read many times that 2 inch is best for first reflection points because it takes care of the highs and mid range frequencies better than 1 inch.

I was not expecting anyone to tell me that 1" would be sufficient. So would my knauf be sufficient to use as a first reflection point absorber for my center channel?

Would I get better performance if I doubled it?


Thank!!!


----------



## Terry Montlick




> Quote:
> Originally Posted by *suffolk112000* /forum/post/13785503
> 
> 
> Well thank you Terry.
> 
> 
> 
> 
> 
> 
> 
> Ask and yea shall receive a prompt answer.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Well, I have read many times that 2 inch is best for first reflection points because it takes care of the highs and mid range frequencies.
> 
> I was not expecting anyone to tell me that 1" would be sufficient. So would my knauf be sufficient to use as a first reflection point absorber for my center channel?
> 
> Would I get better performance if I doubled it?



Not for specific control of early reflections. It is hard to know whether your room would benefit from the extended lower frequency absorption of 2" material without acoustical measurements and analysis.


Regards,

Terry


----------



## yngdiego




> Quote:
> Originally Posted by *suffolk112000* /forum/post/13785308
> 
> 
> Another slightly off topic question. For those that have used 703 and 705, it seems like the lighter yellowish color of the insulation would show through black GOM. Especially when light hits it. My center is VERY close to the ceiling. Because I will have to put the panel somewhat close to the screen. This is a big concern for me.
> 
> 
> Thanks in advance.



No, it does not show through at all. 100% opaque.


----------



## Dan Woodruff

Terry,


Can I get a bit of clarification, please?


I noticed that earlier in this thread you suggested, when using this method, you prefer 2" of semi-rigid fiberglass on the front wall as opposed to 1". In the post above, I believe you have also said this many times before, you tell us that 1" inch is sufficient for early reflection points.


Can you help me better understand why the front wall needs to be "deader" than the first reflection points along the side walls? I know that this helps imaging but I'm not quite understanding how that happens. How much improvement will the extra inch of semi-rigid fiberglass offer? I have some extra and wonder if I should go ahead put it up since I'm still in the building phase.


I have already built and installed the "chunk style" or "wedge" bass traps (24x17x17) in the front-side corners and have 1" Linacoustic covering the entire front wall. The side walls (at the moment) have 1" Linacoustic from the floor to 49". The rear wall is bare. The room is 13x21.2x7.5. The floor is not carpeted yet but that will go down over the heart pine as soon as the A/C is complete next week.


My room images very well, as it is now, and I am certain the sound will change quite a bit once the carpet is down. I suspect that I may need to reduce the amount of linacoustic on the side walls. Any suggestions you might have are greatly appreciated.


Thanks,

Dan


----------



## Terry Montlick




> Quote:
> Originally Posted by *affeking* /forum/post/13781543
> 
> 
> Any suggestions on what I use for the first reflections instead? And I went for the traps on the back wall with the thought of 'the more bass traps the better' and I'd heard it was important to treat them behind the listening spot. Any alternate suggestions??
> 
> 
> Thanks...
> 
> Jeff



Hi again Jeff,


Specifically for first reflections, you need only 1" of fiberglass or equivalent absorber. But with only 5 feet to your back wall, you have other problems.










You are likely to have some low frequency notches starting pretty far down. Use as much absorption depth, and/or space the absorber as far from the wall as humanly possible, or as WAF will allow!










Regards,

Terry


----------



## affeking

Thanks for the response Terry.


With the 5' issue...would I be better off violating the 38% guideline and moving the couch further up? I would also consider building free standing frames for the panels and putting them just behind the listener, but it may get in the way of the A/V rack.


Here's a pic of my layout roughly.
http://picasaweb.google.com/jrames/T...82471775025394 


The speaker layout is approximate, and is going to change as I test / add absorbers. I don't have all of the relative distances in there, but the listeners ears are just about 5' from that rear wall as I stated. The main theater area is 18x21 with 81" ceilings (yes, its like a hobbit cave). Most of the remaining area is enclosed with drywall, except for that hallway just to the bottom right of the theater area and the nook leading into the stairway.


Jeff


----------



## Terry Montlick

Hi Jeff,


You realize that acoustical consulting is my sole source of income (I don't sell *any* treatment products), right?










I am more than happy to provide general treatment guidlines, tips, etc. But at some point, one gets into more detailed design, everything interacts with everything else, and one cannot isolate just one piece of a design and provide a "sound" recommendation. For that I need much more information and would have to devote significant time resources to analyze it. It is like an MD giving diagnosis and treatment over the web. This is not a good idea, and to some degree, constitutes malpractice because a detailed medical exam has not been performed.


Feel free to take the advice of others. But it is really hard for me to weigh in any further as a profession without quite possibly being off base, and compromising my standards. Hope you understand.










Regards,

Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13785524
> 
> 
> Not for specific control of early reflections. It is hard to know whether your room would benefit from the extended lower frequency absorption of 2" material without acoustical measurements and analysis.
> 
> 
> Regards,
> 
> Terry



Terry,


One inch absorption falls off dramatically under 1k compared to 2". Shouldn't first reflection point absorbers go at least to 500Hz? And don't most spaces used for home theaters benefit, generally, from the additional absorption down to ~250Hz of the 2"?


- Jeff


----------



## affeking




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13786791
> 
> 
> Feel free to take the advice of others. But it is really hard for me to weigh in any further as a profession without quite possibly being off base, and compromising my standards. Hope you understand.



No problem. I was actually posting the layout and specifics for everyone to comment on. The only reason I asked for some specific clarification was because you'd given me some specific advice. Point taken...


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/13787133
> 
> 
> Terry,
> 
> 
> One inch absorption falls off dramatically under 1k compared to 2". Shouldn't first reflection point absorbers go at least to 500Hz? And don't most spaces used for home theaters benefit, generally, from the additional absorption down to ~250Hz of the 2"?
> 
> 
> - Jeff



I have found that in practice, 1" thick rigid or semi-rigid fiberglass is completely adequate to sufficiently attenuate early reflections as measured by an energy energy time curve.


Regards,

Terry


----------



## Dennis Erskine

...also, some current research suggests that diffusion can be appropriate for early reflections. This decision would hinge upon the quality of the off axis response of the specific speaker being used.


----------



## cuzed2

Terry, Bryan, Ethan,


Need your input on the post below. I have a dywaller coming soon, and I need to decide if I should drywall, or treat the walls immediatly adjacent to my screen.


My screen wall will be treated with 6" of insulation (possibly with 2" of OC if you reccomend) and covered with 1" linacoustic, and GOM.


The vertical front corners will include floor to ceiling Basstraps, 17x17x24.

I will also be making panel(s) to cover my first reflection points about 7' away from the screen.


Not sure with my semi-open floorplan >> if there is much advantage to covering the first 3~5 feet of sidewall adjacent to my screen...?


Thanks In Advance,

Craig




> Quote:
> Originally Posted by *cuzed2* /forum/post/13749391
> 
> 
> Question(s) for the acoustic experts that are lurking...
> 
> 
> The sketch below is the layout of my theater area. As you can see I have compromised in order to have a somewhat open floor plan, leaving an open game area to the left of the theater area. I have since boxed in the areas (in red) to the LH and RH side of the screen, in the sketch below, this was done to hide utilities in the front RH corner, and (on the left) to keep things symmetrical.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The actual photo below is where I am today.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I will be adding floor to ceiling bass traps (OC703) in the front corners, and I will be insulating the studs with pink stuff between the studs on the screen wall, and plan to cover the front wall with linacoustic and GOM.
> 
> 
> My question: should I also treat the sidewalls immediatly adjacent to the LH and RH side of the screen?
> 
> 
> Other info and questions:
> 
> 
> The finished ceiling height will be 7'9", the ceiling joists will be stuffed with insulation, and then using the ceiling max system will be finished with acoustical tile.
> 
> 
> I am planning on stuffing the soffits with pink stuff, then drywalling the underside and vertical surface of the soffits - Is this a mistake?
> 
> 
> I will try to hit the reflection points with panels (at least the RH side). Should I treat the back wall? Would there be any benefit to putting corner traps in the upper rear corners instead? How about corner traps in the upper corenrs of the adjoining game room area?
> 
> 
> Thanks in Advance!


----------



## Terry Montlick




> Quote:
> Originally Posted by *cuzed2* /forum/post/13791851
> 
> 
> Not sure with my semi-open floorplan >> if there is much advantage to covering the first 3~5 feet of sidewall adjacent to my screen...?
> 
> 
> Thanks In Advance,
> 
> Craig



Yes, I would build it out as much as possible. Symmetry at the front of the room can make a *big* difference in the evenness of sound from your front speakers.


Regards,

Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *cuzed2* /forum/post/13791851
> 
> 
> Not sure with my semi-open floorplan >> if there is much advantage to covering the first 3~5 feet of sidewall adjacent to my screen...?



I agree with Terry that symmetry is important, especially in the front part of the room. Also, the side walls reflection points probably extend further back in the room, so be sure to treat back far enough. Likewise, the ceiling reflection points. The rear wall can be a source of "early" reflections if it's closer than 10 feet from any seats. The rear wall is also a prime source of peaks and nulls at low frequencies.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *cuzed2* /forum/post/13791851
> 
> 
> Terry, Bryan, Ethan,
> 
> 
> Need your input on the post below. I have a dywaller coming soon, and I need to decide if I should drywall, or treat the walls immediatly adjacent to my screen.



I don't think "or" is the right question. Drywall and then treat.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13785758
> 
> 
> Terry,
> 
> 
> Can I get a bit of clarification, please?
> 
> 
> I noticed that earlier in this thread you suggested, when using this method, you prefer 2" of semi-rigid fiberglass on the front wall as opposed to 1". In the post above, I believe you have also said this many times before, you tell us that 1" inch is sufficient for early reflection points.
> 
> 
> Can you help me better understand why the front wall needs to be "deader" than the first reflection points along the side walls? I know that this helps imaging but I'm not quite understanding how that happens. How much improvement will the extra inch of semi-rigid fiberglass offer? I have some extra and wonder if I should go ahead put it up since I'm still in the building phase.
> 
> 
> I have already built and installed the "chunk style" or "wedge" bass traps (24x17x17) in the front-side corners and have 1" Linacoustic covering the entire front wall. The side walls (at the moment) have 1" Linacoustic from the floor to 49". The rear wall is bare. The room is 13x21.2x7.5. The floor is not carpeted yet but that will go down over the heart pine as soon as the A/C is complete next week.
> 
> 
> My room images very well, as it is now, and I am certain the sound will change quite a bit once the carpet is down. I suspect that I may need to reduce the amount of linacoustic on the side walls. Any suggestions you might have are greatly appreciated.
> 
> 
> Thanks,
> 
> Dan



Sorry I missed your question earlier, Dan.


Basically, early reflection image problems happen at medium to high frequency. At these frequencies, your speakers are mostly radiating forward, not omnidirectionally. So early reflections travelling backwards from speakers to the front wall are not an issue. They certainly *can* be for the side walls, ceiling, and floor, depending on the directivity and positions of your front speakers.


The thicker absorption at the front wall is to help deal with low frequency reflections, which are much more omnidirectional. In fact, at subwoofer frequencies emanating from a typical subwoofer-sized box, the sound radiation is perfectly omnidirectional.


Now, 2" isn't going to get you much into the subwoofer range at all. But it is a good practical compromise for most people. It will help a lot with potentially interfering reflections in the 3 figures of hertz, which will be fairly omnidirectional.


Regards,

Terry


----------



## Dan Woodruff

Terry,


Thanks for the answers. That helps clear it up somewhat.


Given the limited information I have already provided, do you feel my room would benefit from the extra inch of linacoustic on the front wall or are the "wedge" bass traps and 1" sufficient? If the extra inch will make a difference, what difference(s) should I expect and/or notice?


Thanks,

Dan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13792890
> 
> 
> Terry,
> 
> 
> Thanks for the answers. That helps clear it up somewhat.
> 
> 
> Given the limited information I have already provided, do you feel my room would benefit from the extra inch of linacoustic on the front wall or are the "wedge" bass traps and 1" sufficient? If the extra inch will make a difference, what difference(s) should I expect and/or notice?
> 
> 
> Thanks,
> 
> Dan



I'd recommend using an extra inch on the front wall, if you have the fiberglass. This will not affect imaging, but can improve the response (reduce coloration) in above-subwoofer frequency bass. I cannot tell you what you will personally experience or notice. But I would expect there to be some measurable improvement in the steady-state frequency response.


Regards,

Terry


----------



## Dan Woodruff

Terry,


Thanks again! I have plenty of spare linacoustic so I'll put an another inch up tomorrow while the A/C guys are installing the ductwork.


Thanks,

Dan


----------



## BasementBob

Re 1" or 2":


> Quote:
> Early reflections are defined as reflections from boundary surfaces or other surfaces in the room which reach the listening area within the first 15 ms after the arrival of the direct sound. The levels of these reflections should be at least 10 dB below the level of the direct sound for all frequencies in the range 1 kHz to 8 kHz.



from: EBU Tech. 3276 - 2nd edition


----------



## Terry Montlick

Thanks for bringing up this reference, Bob. At 1 kHz, 1-inch of rigid or semi-rigid fiberglass will absorb about 90+% of the energy incident upon it. This corresponds to a drop in reflected energy of 10 dB or more. Since the position of the early reflection surfaces are off-axis, they will get somewhat less than the full on-axis response, and the reflection will be even weaker. Hence 1-inch fiberglass is more than enough to sufficiently reduce early reflections.


Or just try it. It works.










Regards,

Terry


----------



## distoga

For a room with all wall, floor and ceiling surfaces of 8"-20" of concrete, how does 2" front insulation (AT screen), 4" ceiling, 6" rear, 2" sides up to 48" and two 24"x24"x34" super chunks in the front corners sound? The local supplier has Rockwool RHT 40:


RHT 40 2" (51mm) 3.5 pcf (56 kg/m3) 0.26 0.68 1.14 1.13 1.06 1.07 1.00

RHT 40 4" (100mm) 3.5 pcf (56 kg/m3) 1.07 1.01 1.07 1.06 1.07 1.16 1.05


To get 4" and 6" I'll be layering 2" 4'x8' sheets.


The walls have eight 20" wide columns made of 1" MDF (about 20%-30% of the side and back wall surface area is MDF with no treatment) and 1' wide soffit around the room's ceiling, made of MDF with 7" of crown made of the ultralight decorative molding (so really only 5" of flat face on the soffit is exposed). Between the columns will be thin fabric (to be picked) to let most sound through to get some reflections above ear level.


Because of water problems, all insulation and columns are held 1" off the wall to allow water to flow behind it to drains and there is no framing or drywall except near the entry into the room. Carpet is outdoor carpet/commercial like that can get wet and not very thick.


I've bought a feedback pro, test microphone, mixer, and all the other equipment to do testing but before I buy all this insulation I wanted to make sure I was fairly close on my choices.


I will be getting some paper to adhere to possibly the back wall or ceiling insulation to reflect highs. The main reason for all the insulation is try to kill the massive amounts of bass that the cement walls will reflect. That's why I'm looking at 2" min on walls, so I can get something with over a 1.x noise reduction in the bass range and evenly kill everything rather than taking too much highs but not bass.


For audio equipment it will likely be the Denon AVR-4308CI with 140Watts per channel in a 7.1 configuration and RBH or Energy speakers. Two subs, yet to be picked.










(Column will be covered in Dazian celtic cloth so they look full height and surround speakers will be placed in some columns)


----------



## distoga

I just got a price quote for the insulation for my room and it was well over a grand... :O I can get linacoustic RC for nearly a forth of the price and other threads say linacoustic is fairly close to 703 even though linacoustic is slightly less dense? How about a rear wall with three 2" linacoustic layers to get the 6"?, ceiling done with linacoustic (or atleast one of two layers with it) and everything but the bass traps in 2" linacoustic, also maybe do 17x17x24 rather than 24x24x34 bass traps?


----------



## Dan Woodruff

Terry,


I placed the extra inch of linacoustic on the front wall this morning and had a chance to check out the sound briefly. The A/C guys took an hour for lunch so I didn't have a lot of time. It definitely improved the quality of the mids and high bass. The room sounds "deader" overall. I guess I was getting a bit of resonance from the screen or something but whatever it was, that is gone. Is this the "coloration" you mentioned?


Anyway, THANKS!!!!! The room sounds better.


----------



## CruelInventions




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/13788484
> 
> 
> ...also, some current research suggests that diffusion can be appropriate for early reflections. This decision would hinge upon the quality of the off axis response of the specific speaker being used.



as in, the greater off axis speaker response, the more applicable diffusion types of treatment might be? or would it be the converse, i.e., absorption more often applicable?


----------



## pepar




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13801238
> 
> 
> as in, the greater off axis speaker response, the more applicable diffusion types of treatment might be? or would it be the converse, i.e., absorption more often applicable?



I believe Dennis is referring to Toole's recent work. If so, it's as in the flatter the off-axis response, the more diffusion may be better than absorption. Or no treatment at all. This applies only to lateral reflections.


----------



## Dennis Erskine

Not exactly the flatter the off axis response ...


You'd expect response to roll off as you go off axis...good off axis response would mean the shape of the response curves would be the same except for the roll off.


----------



## CruelInventions

Let me put my question another way, in hopes of eliciting a response that even my feeble mind can grasp.







...


To put it more simply, the better your speakers are at providing good sound outside of the "sweet spot" (or at least, similar sound to what you hear in the sweet spot), the more applicable the diffusion or 'no treatment at all' tactics might be for those particular speakers?


For example, I've been considering the purchase of some Ascend Sierra speakers, which have a design priority for just that, to sound just as good or very nearly as good from more than just the primary seating location, as opposed to some other speaker designs which are designed to sound great in the "sweet spot", but fall down a bit more when the listener is positioned in other secondary seating locations.


----------



## pepar




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13802211
> 
> 
> Let me put my question another way, in hopes of eliciting a response that even my feeble mind can grasp.
> 
> 
> 
> 
> 
> 
> 
> ...
> 
> 
> To put it more simply, the better your speakers are at providing good sound outside of the "sweet spot" (or at least, similar sound to what you hear in the sweet spot), the more applicable the diffusion or 'no treatment at all' tactics might be for those particular speakers?
> 
> 
> For example, I've been considering the purchase of some Ascend Sierra speakers, which have a design priority for just that, to sound just as good or very nearly as good from more than just the primary seating location, as opposed to some other speaker designs which are designed to sound great in the "sweet spot", but fall down a bit more when the listener is positioned in other secondary seating locations.



I think the off axis we're talking about with regards to treating the left and right front first reflection points is much further off axis than a few seats left and right of a sweet spot. Beyond that, I don't think it's knowable in advance of installing the Ascends in your theater whether they will sound better with absorbers, diffusors or nothing at those points.


Just my feeble $.02.


----------



## bpape

IMO, very very few speakers have the kind of smooth, identical off-axis response to qualify. When you consider how many seats we're talking about and the severe off axis waves that are reflected to seating, IMO, absorbtion is still appropriate 99% of the time.


As for the front wall, while there are no mid and high frequency issues from the mains, thicker absorption can absolutely be used to tame SBIR issues - or - NOT used to deliberately allow SBIR to be USEFUL in compensating for anomolies caused by other issues that may not be able to be dealt with any other way.


This is where what Terry was saying earlier comes into play. It's great to get general recommendations but to really get into the details takes a lot of information and a lot of work doing an analysis.


Bryan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/13800527
> 
> 
> Terry,
> 
> 
> I placed the extra inch of linacoustic on the front wall this morning and had a chance to check out the sound briefly. The A/C guys took an hour for lunch so I didn't have a lot of time. It definitely improved the quality of the mids and high bass. The room sounds "deader" overall. I guess I was getting a bit of resonance from the screen or something but whatever it was, that is gone. Is this the "coloration" you mentioned?
> 
> 
> Anyway, THANKS!!!!! The room sounds better.



You are very welcome, Dan. Glad this worked for you!


Regards,

Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/13801632
> 
> 
> Not exactly the flatter the off axis response ...
> 
> 
> You'd expect response to roll off as you go off axis...good off axis response would mean the shape of the response curves would be the same except for the roll off.



Yup. And most speaker manufacturers (especially at the high, very expensive end) just hate to make public their off-axis responses. They are often less than ideal.


Regards,

Terry


----------



## dromayn

Will this type of Material be as absorbent as the other JM acoustic insulation mentioned here? Here is the link...

http://www.jm.com/insulation/perform..._microlite.pdf


----------



## BobL

Also, off axis response has to account for 'toe in' of the speakers. So a good off axis response facing forward might not be if you prefer to 'toe in' your speakers.


Bob


----------



## CruelInventions




> Quote:
> Originally Posted by *pepar* /forum/post/13802417
> 
> 
> I think the off axis we're talking about with regards to treating the left and right front first reflection points is much further off axis than a few seats left and right of a sweet spot. Beyond that, I don't think it's knowable in advance of installing the Ascends in your theater whether they will sound better with absorbers, diffusors or nothing at those points.
> 
> 
> Just my feeble $.02.





> Quote:
> Originally Posted by *bpape* /forum/post/13803942
> 
> 
> IMO, very very few speakers have the kind of smooth, identical off-axis response to qualify. When you consider how many seats we're talking about and the severe off axis waves that are reflected to seating, IMO, absorbtion is still appropriate 99% of the time.



I'm not building a home theater. I'm just here to absorb more info on acoustic treatments in general.


So if I'm reading you both correctly, then sidewall diffusion or even no treatment at all on side walls _could_ be within the realm of possibility for less taxing environments (those rooms which aren't very large across, nor having to contend with several rows/columns of seating, etc., coupled with owning that rare speaker which performs smoothly enough off-axis in the ways being described here).


So, still.. probably not very likely, but at least something to bare in mind (that treating side wall first reflections shouldn't be considered an automatic absolute given). In other words, MOST rooms of any kind would need sidewall first reflection absorption, but there are those occasional exceptions where this won't be necessary. So don't force yourself to keep absorption treatments in place if you find that it doesn't sound as good as without because it just might not sound as good, afterall.


Hope I got this right.


----------



## pepar




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13809415
> 
> 
> I'm not building a home theater. I'm just here to absorb more info on acoustic treatments in general.
> 
> 
> So if I'm reading you both correctly, then sidewall diffusion or even no treatment at all on side walls _could_ be within the realm of possibility for less taxing environments (those rooms which aren't very large across, nor having to contend with several rows/columns of seating, etc., coupled with owning that rare speaker which performs smoothly enough off-axis in the ways being described here).
> 
> 
> So, still.. probably not very likely, but at least something to bare in mind (that treating side wall first reflections shouldn't be considered an automatic absolute given). In other words, MOST rooms of any kind would need sidewall first reflection absorption, but there are those occasional exceptions where this won't be necessary. So don't force yourself to keep absorption treatments in place if you find that it doesn't sound as good as without because it just might not sound as good, afterall.
> 
> 
> Hope I got this right.



Most people have NO acoustical treatments. That they're on your list puts you ahead of the game already. If you're going it alone (w/o a pro), then go slow. FWIW, in my room with my rear (money) row 6' from the rear wall, the absorber that made, by far, the biggest improvement in sound was the one on the rear wall. Getting rid of that 12ms delayed reflection was a real eye-(and ear-)opener.


The new thinking by some regarding diffusion or nothing on the front side walls is just that - new. Though it's being put forth by well-respected acoustician, I think most people you'll find here are still firmly in the "treat it" camp.


----------



## allredp




pepar said:


> FWIW, in my room with my rear (money) row 6' from the rear wall, the absorber that made, by far, the biggest improvement in sound was the one on the rear wall. Getting rid of that 12ms delayed reflection was a real eye-(and ear-)opener.
> 
> 
> 
> Hey Pepar,
> 
> 
> What did you do for your rear absorber (materials, thickness, dimension, wall placement)? Sorry if you said earlier...
> 
> 
> I'm only 3' off the back and I'm experienceing some serious "notches" (per Terry/Ethan/Bryan) in my bass response.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks man,
> 
> Phil
Click to expand...


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/13810006
> 
> 
> Hey Pepar,
> 
> 
> What did you do for your rear absorber (materials, thickness, dimension, wall placement)? Sorry if you said earlier...
> 
> 
> I'm only 3' off the back and I'm experienceing some serious "notches" (per Terry/Ethan/Bryan) in my bass response.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks man,
> 
> Phil



My absorbers are 2" Owens Corning SelectSound Black.


----------



## bpape




> Quote:
> Originally Posted by *CruelInventions* /forum/post/13809415
> 
> 
> I'm not building a home theater. I'm just here to absorb more info on acoustic treatments in general.
> 
> 
> So if I'm reading you both correctly, then sidewall diffusion or even no treatment at all on side walls _could_ be within the realm of possibility for less taxing environments (those rooms which aren't very large across, nor having to contend with several rows/columns of seating, etc., coupled with owning that rare speaker which performs smoothly enough off-axis in the ways being described here).
> 
> 
> So, still.. probably not very likely, but at least something to bare in mind (that treating side wall first reflections shouldn't be considered an automatic absolute given). In other words, MOST rooms of any kind would need sidewall first reflection absorption, but there are those occasional exceptions where this won't be necessary. So don't force yourself to keep absorption treatments in place if you find that it doesn't sound as good as without because it just might not sound as good, afterall.
> 
> 
> Hope I got this right.



Actually, just the opposite. Diffusion could be used in LARGER environments and with speakers that have exceptional off axis sperformance. Absorbtion is needed if either or both of those conditions are not met. IMO, no treatment at side wall reflections in any normal sized residential enivornment is not a viable option.


Bryan


----------



## Dennis Erskine




> Quote:
> Also, off axis response has to account for 'toe in' of the speakers. So a good off axis response facing forward might not be if you prefer to 'toe in' your speakers.



All the "toe-in" will do, is change the axis from which the side wall reflections reach the ears from the speaker (well, axis and dB).


Cruel...

Speakers don't know if they are in a home theater or some other type of environment. Acoustic treatments are dictated by the room, seating, speaker characteristics, etc. All rooms require some form of acoustic treatment. In a typical residential sized space, on the order of 80% of the sound you hear is NOT coming directly from the speakers ... it's coming from the room. That's a significant share (good or bad). At the end of the day, no speaker ($80K or otherwise) and no magic electronic device can overcome the effects of the room, nor violate the rules of physics.


----------



## Mupi

I am just venturing into the area of bass traps after folks suggested that bass traps is the way to go to take care of peaks and dips instead of parametric EQ.

I noticed that OC 703, Rockwool 60 etc only start from 125Hz.

I was wondering what other material I could consider if I have to

cover from say 30hz to 200Hz. Any feedback is appreciated

Thanks


----------



## pepar




> Quote:
> Originally Posted by *Mupi* /forum/post/13813949
> 
> 
> I am just venturing into the area of bass traps after folks suggested that bass traps is the way to go to take care of peaks and dips instead of parametric EQ.
> 
> I noticed that OC 703, Rockwool 60 etc only start from 125Hz.
> 
> I was wondering what other material I could consider if I have to
> 
> cover from say 30hz to 200Hz. Any feedback is appreciated
> 
> Thanka



Those numbers are for sheets. When bass traps are constructed like this , they reach lower. Also, check the link in my sig as I just installed some.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Mupi* /forum/post/13813949
> 
> 
> I noticed that OC 703, Rockwool 60 etc only start from 125Hz.



That's because most labs that measure absorbers are not certified to report below 100 Hz. This doesn't mean the materials suddenly stop working below that frequency. Much more info here if you care:

http://www.realtraps.com/art_testing.htm 


--Ethan


----------



## Mupi

pepar, ethan thanks for the explanation.


I am considering the rockwool as people say that it is cheaper than the OC703. Also I can get the rockwool panels in 4'' thickness where as the 703 only comes in 1 or 2'' thickness.


Now my question is whether I should get the rockboard or the RHT.

I guess the rockboard is rigid where as the RHT is semi rigid. I may not cut them into triangles. I am going to just place the panels at the corner and sides. If that is promising then I will take the trouble of cutting.


Also I prefer to order either the rockwool or OC703 online instead of hunting down a local dealer, arranging for a transport etc. Is there a reliable online place for either of these? One of my coworkers has already done a lot of search and I dont think he found an online place.


Thanks


----------



## armstrr




> Quote:
> Originally Posted by *Mupi* /forum/post/13817910
> 
> 
> pepar, ethan thanks for the explanation.
> 
> 
> I am considering the rockwool as people say that it is cheaper than the OC703. Also I can get the rockwool panels in 4'' thickness where as the 703 only comes in 1 or 2'' thickness.
> 
> 
> Now my question is whether I should get the rockboard or the RHT.
> 
> I guess the rockboard is rigid where as the RHT is semi rigid. I may not cut them into triangles. I am going to just place the panels at the corner and sides. If that is promising then I will take the trouble of cutting.
> 
> 
> Also I prefer to order either the rockwool or OC703 online instead of hunting down a local dealer, arranging for a transport etc. Is there a reliable online place for either of these? One of my coworkers has already done a lot of search and I dont think he found an online place.
> 
> 
> Thanks



do a search for acoustic insulation on ebay...both are available


----------



## dbbarron

From a few weeks ago after I posted some room response data, Terry commented:



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13734166
> 
> 
> Hi db,
> 
> 
> I'd say that your reverberations times in the octave bands 125 Hz and 250 Hz are a bit too high relative to the higher frequency octave bands. These higher frequency octave band reverberation times are not too low on an absolute scale, but too low on a scale relative to the 125 Hz and 250 Hz octave bands. This unevenness can make the room sound too dead. As for the 63 Hz octave band, reverberation time measurement at these low frequencies is too unreliable in small rooms to be useful.
> 
> 
> But since your upper frequencies are fine, you just need more absorption at the highly treatable 125 Hz and 250 Hz octave bands. I recommend either DIY bass traps, as described in this forum and on http://forum.studiotips.com/viewtopic.php?t=535 , or ready-made bass traps by forum members RealTraps or GIK Acoustics.
> 
> 
> Regards,
> 
> Terry



I have since then doubled the sidewall linacoustic to 2" in hopes of absorbing some lower frequencies without further absorbing the higher frequencies. I also treated the ceiling first reflection point.


Data is below:


First, measurements of impulse response in the room with 1" sidewall linacoustic and no ceiling treatement:











Second, with ceiling (first reflection point) and 2" sidewall treatement











Now RT60: Red is no treatment, green is with one inch sidewall treatment and yellow is with two inch treatment. These are 1 octave averages, with 1/3 octave averaging the 2" graph is lower than the 1" as expected except for one errant point which sets off the 1 octave average.











Lastly, waterfalls; first no treatment











Second, with 1" sidewall treatement











Third with 2" sidewall treatment











I think, to Terry's point, I have addressed the 125-250hz region and ceiling reflection as (separately) suggested. The sound is good, but subjectively, now a bit thin in the mid bass. Will have to think about this a bit.


The big question....am I there yet?


Comments welcome..


db


----------



## penngray

db, Im about to do the same measurements. Its that REW that does all that?


I have carpet installed, my 4 berkliners and audio setup to do measurements before treatments and after.


----------



## pepar




> Quote:
> Originally Posted by *Mupi* /forum/post/13817910
> 
> 
> pepar, ethan thanks for the explanation.
> 
> 
> I am considering the rockwool as people say that it is cheaper than the OC703. Also I can get the rockwool panels in 4'' thickness where as the 703 only comes in 1 or 2'' thickness.
> 
> 
> Now my question is whether I should get the rockboard or the RHT.
> 
> I guess the rockboard is rigid where as the RHT is semi rigid. I may not cut them into triangles. I am going to just place the panels at the corner and sides. If that is promising then I will take the trouble of cutting.
> 
> 
> Also I prefer to order either the rockwool or OC703 online instead of hunting down a local dealer, arranging for a transport etc. Is there a reliable online place for either of these? One of my coworkers has already done a lot of search and I dont think he found an online place.
> 
> 
> Thanks



A local "dealer" would actually be an HVAC insulation distributor such as SPI . Any online source you find will likely be selling the stuff as home theater acoustical absorption instead of HVAC insulation for commercial construction projects. Think about that and the impact on pricing. Also, you will probably find out quickly that, due to the volume (size), shipping costs are high.


Just my $.02.


----------



## dbbarron




> Quote:
> Originally Posted by *penngray* /forum/post/13818748
> 
> 
> db, Im about to do the same measurements. Its that REW that does all that?
> 
> 
> I have carpet installed, my 4 berkliners and audio setup to do measurements before treatments and after.



Yes - all with REW, a behringer measurement mic and a small mixer to provide phantom power. About a $125 setup additional to the PC.


----------



## penngray




> Quote:
> Also I prefer to order either the rockwool or OC703 online instead of hunting down a local dealer, arranging for a transport etc. Is there a reliable online place for either of these? One of my coworkers has already done a lot of search and I dont think he found an online place.



I bought my OC703 from ebay (best price I could find for 12 1" sheets)


I bought ULTRA touch cotton fibre from soundaway.com .....CHECK THIS STUFF OUT!!! Great for corner bass chunks and its not fibreglass or rockwool, nicer to work with.


I bought rockwool 60 from ATSAcoustics.com


I could have bought some DUCT LINER that works the same way as above from my local HVAC supplier but I already ordered the stuff online. The stuff was from CertainTeed Corp and its also perfect for sound absorption. Call your local HVAC company first BUT DO NOT ask for acoustical liner, instead just ask about duct liner....products with Acoustical in them have a premium price tag!!


----------



## penngray




> Quote:
> Yes - all with REW, a behringer measurement mic and a small mixer to provide phantom power. About a $125 setup additional to the PC.



I have REW, a RS digital SPL meter and a PC. I dont have a clue about the small mixer to provide phantom power. I have used REW before to test my sub but never did waterfall stuff. I guess its time to read the REW FAQ on hometheatershack.com and get it working this weekend again.


----------



## eugovector

Question on RT 60, how low it too low to go?


In dbbarron's post above, there's this graph:

http://idisk.mac.com/dbbarron1-Publi...comparison.jpg 


I've heard that you want to hit about .3 seconds, and he closes in on .2 for most of the range. Is .2 too dead? Is this a matter of personal taste?


----------



## eugovector




> Quote:
> Originally Posted by *penngray* /forum/post/13820447
> 
> 
> I bought ULTRA touch cotton fibre from soundaway.com .....CHECK THIS STUFF OUT!!! Great for corner bass chunks and its not fibreglass or rockwool, nicer to work with.



I'm very intrigued by this product, it seems when making superchunk bass traps and absorption behind a fabric wall (not rigid enough to frame in panels?), this is a fairly attractive solution.


This is what I see...


Pros:

Non irritating

"Green"

Great acoustical performance, especially in the lower frequencies.

Comparatively priced compared to OC703 (For $120 shipped, I got 96 sq.ft. of 2" 703, $180 shipped for 126 sq.ft. of 3.5" cotton)


Cons:

not rigid enough to frame in panels?

hard to stack into super chunks?


Can you tell us about your experiences working with this material. Is it easy to frame? Will it stack into superchunks and not sag and tip over? Anything in the list that I'm missing?


----------



## cavchameleon




> Quote:
> Originally Posted by *eugovector* /forum/post/13820605
> 
> 
> I'm very intrigued by this product, it seems when making superchunk bass traps and absorption behind a fabric wall (not rigid enough to frame in panels?), this is a fairly attractive solution.
> 
> 
> This is what I see...
> 
> 
> Pros:
> 
> Non irritating
> 
> "Green"
> 
> Great acoustical performance, especially in the lower frequencies.
> 
> Comparatively priced compared to OC703 (For $120 shipped, I got 96 sq.ft. of 2" 703, $180 shipped for 126 sq.ft. of 3.5" cotton)
> 
> 
> Cons:
> 
> not rigid enough to frame in panels?
> 
> hard to stack into super chunks?
> 
> 
> Can you tell us about your experiences working with this material. Is it easy to frame? Will it stack into superchunks and not sag and tip over? Anything in the list that I'm missing?



Hi eugovector,


I was interested in this product also and contacted them. They have two products, regular wall insulation and Acoustic Cotton Panels:

http://www.soundaway.com/acoustic_co...anels_s/91.htm 


These are pretty ridgid and will hold up if cut for bass traps in corners. As for panel mounting without sagging, this is one of the emails sent to me (I too wanted to us them for panels an not to use fiberglass):

Here is the approximate weight per panel:



1" thick x 2' x 4' = 2 lbs.

2" thick x 2' x 4' = 4 lbs.

4" thick x 2' x 4' = 8 lbs.



It is recommended to mount them with a spray adhesive that bonds quickly and a long-term adhesive that will secure on a long-term basis. The spray adhesive is sprayed across the back of the panel while the second adhesive is applied in a bead around the perimeter and across the diagonal of the opposite corners. They will not sag if you use both adhesives.



The spray adhesive covers 64 square feet per can and is priced at $9.95 each. The long-term adhesive, Acoustic-Bond Adhesive, covers 80 lineal feet at 1/4" bead and is priced at $9.95 also. Plan on using 1 can of Acoustic-Bond Adhesive per 4 panels (2' x 4' per panel).



Alex
[email protected] 


760-599-3985

760-599-4508 (Fax)

Visit us at www.SoundAway.com


I also asked them about material sloughing off and this is their response:

One of the key benefits of using UltraQuiet Acoustic Cotton Panels is being able to hang them without a fabric finish. The panels are made from tightly compressed cotton fibers and do not shed nor release anything into the air. You may, for aesthetic reasons, choose to cover them with GOM fabric that we carry.


Attached you'll find the sound absorbency performance for the panels along with their respective NRC rating.


Call me if you need further assistance.


I look forward to hearing from you.


Alex
[email protected]


With the last email they sent me a PDF of the NRC's of their ascoustic cotton pannels. They look pretty good. Contact them, they are very helpful. I'm still deciding what I need for my room.


Ray


----------



## penngray




> Quote:
> With the last email they sent me a PDF of the NRC's of their ascoustic cotton pannels. They look pretty good. Contact them, they are very helpful. I'm still deciding what I need for my room.



I have order the 3.5" utratouch from soundaway.com, 230 sq ft of it, Shipping is a little pricey at $60 but overall the price is similar too OC703 or Rockwool 60. It was easy to order and shipment came pretty fast!


The only thing cheaper is to order duct liner from local HVACs because its closer to $1/sq ft because you can pick it up...its the shipping that is increasing the prices by 50%.


As for the NRCs, ALL of them are on Bob Golds website link that is constantly referred to here....

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## cavchameleon




> Quote:
> Originally Posted by *penngray* /forum/post/13820762
> 
> 
> I have order the 3.5" utratouch from soundaway.com, 230 sq ft of it, Shipping is a little pricey at $60 but overall the price is similar too OC703 or Rockwool 60. It was easy to order and shipment came pretty fast!
> 
> 
> The only thing cheaper is to order duct liner from local HVACs because its closer to $1/sq ft because you can pick it up...its the shipping that is increasing the prices by 50%.
> 
> 
> As for the NRCs, ALL of them are on Bob Golds website link that is constantly referred to here....
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm



Thanks penngray,


I didn't realize that. I try to keep up with some of the forums, but with a 20month old, I'm pretty busy with other things. Great and informative forum by the way!!! Thanks for all the info.


----------



## penngray

Here are some comparisons of the ultratouch....


OC703, plain 4" (102mm) on wall 3.0 pcf (48 kg/m3) 0.84 1.24 1.24 1.08 1.00 0.97 1.15

Rockwool RXL 40 4" (100mm) 4.0 pcf (64 kg/m3) 1.03 1.07 1.12 1.04 1.07 1.08 1.10

Ultra Touch R-13 3.5" (mm) A 0.95 1.30 1.19 1.08 1.02 1.00 1.15



From this I think Ultra touch is the best $$$ choice....to get 4" OC you have to buy more!!


----------



## penngray




> Quote:
> but with a 20month old, I'm pretty busy with other things




lol, I have a 17 month old girl...but I work out my house and she is in bed at 7:30 pm so lots of time to waste on here










btw, Im building my corner bass traps this weekend...I have 7 big boxes of acoustical material waiting in my garage to get this stuff done but Im holding off on doing it until I run all the numbers before treatment so I can have a baseline for results.


----------



## eugovector




> Quote:
> Originally Posted by *cavchameleon* /forum/post/13820689
> 
> 
> 
> With the last email they sent me a PDF of the NRC's of their ascoustic cotton pannels. They look pretty good. Contact them, they are very helpful. I'm still deciding what I need for my room.
> 
> 
> Ray



Can you post or link the NRC measurements of the panels? Thanks Ray.


Aesthetically, they actually look pretty good. And if they supposedly hold up over time, and their measurements are good, that the lowest price you can find on a finished panel (even my DIY 2" OC 703 panels cost me about $25 each, not counting man-hours). A great deal for those looking to dip their toes into room treatment.


----------



## penngray




> Quote:
> Can you post or link the NRC measurements of the panels? Thanks Ray.



I did above....


----------



## dbbarron




> Quote:
> Originally Posted by *eugovector* /forum/post/13820503
> 
> 
> Question on RT 60, how low it too low to go?
> 
> 
> In dbbarron's post above, there's this graph:
> 
> http://idisk.mac.com/dbbarron1-Publi...comparison.jpg
> 
> 
> I've heard that you want to hit about .3 seconds, and he closes in on .2 for most of the range. Is .2 too dead? Is this a matter of personal taste?



My worries also, but I understand for multichannel surround .2 is an acceptable target. .3 is for two channel (stereo).


To my previous comments, subjectively it is a bit neutral/analytical for stereo listening (actually I am listening in mono during testing)


db


----------



## eugovector




> Quote:
> Originally Posted by *penngray* /forum/post/13820858
> 
> 
> I did above....



I think those are for the flexible rolls, not the rigid panels.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13820447
> 
> 
> I bought my OC703 from ebay (best price I could find for 12 1" sheets)
> 
> 
> I bought ULTRA touch cotton fibre from soundaway.com .....CHECK THIS STUFF OUT!!! Great for corner bass chunks and its not fibreglass or rockwool, nicer to work with.
> 
> 
> I bought rockwool 60 from ATSAcoustics.com
> 
> 
> I could have bought some DUCT LINER that works the same way as above from my local HVAC supplier but I already ordered the stuff online. The stuff was from CertainTeed Corp and its also perfect for sound absorption. Call your local HVAC company first BUT DO NOT ask for acoustical liner, instead just ask about duct liner....products with Acoustical in them have a premium price tag!!



What was the cost for shipping your purchases?


----------



## cavchameleon




> Quote:
> Originally Posted by *eugovector* /forum/post/13820852
> 
> 
> Can you post or link the NRC measurements of the panels? Thanks Ray.
> 
> 
> Aesthetically, they actually look pretty good. And if they supposedly hold up over time, and their measurements are good, that the lowest price you can find on a finished panel (even my DIY 2" OC 703 panels cost me about $25 each, not counting man-hours). A great deal for those looking to dip their toes into room treatment.



eugovector,


Penngray already gave the best link for NRC's for multiple materials. I checked it out, it's incredible and very informative (thanks penngray!). This is what I received from SoundAway:

SoundAway

UltraQuiet Panels

NRC Table

Frequency (Hz) 1" 2" 4"

125 0.08 0.35 0.95

250 0.31 0.94 1.30

500 0.79 1.32 1.19

1000 1.01 1.22 1.08

2000 1.00 1.06 1.02

4000 0.99 1.03 1.00

NRC 0.80 1.15 1.15


I am looking at both the 2" (for reflections), and 4" for bass traps. The finish does already look good, but I may need to still cover with GOM for the WAF.


penngray,

It must be nice to be able to work at home - you get to spend much more time with your kid (except when you're working). I work 10hour days, so have to spend as much time with my son afterwards, then get other things done around the house when he's asleep (at 8pm). I've been thinking of finding work that will allow me to do that also! Thanks for sharring all your info - read some of your other posts/threads. This is a great hobby!!!


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13820451
> 
> 
> I have REW, a RS digital SPL meter and a PC. I dont have a clue about the small mixer to provide phantom power. I have used REW before to test my sub but never did waterfall stuff. I guess its time to read the REW FAQ on hometheatershack.com and get it working this weekend again.



While the RS meter *can* be used as a mic, it is nearly worthless. You would need to buy a suitable mic to get acceptable results with REW. Many use a Beringer mic. The phantom power reference is in re to some mics needing power to operate and that power is supplied over the signal cable . . remotely . . invisibly . . from either a phantom power supply or, in the case of the poster you quoted, a mixer with builtin phantom power.


----------



## eugovector




> Quote:
> Originally Posted by *cavchameleon* /forum/post/13820969
> 
> 
> eugovector,
> 
> 
> Penngray already gave the best link for NRC's for multiple materials. I checked it out, it's incredible and very informative (thanks penngray!). This is what I received from SoundAway:
> 
> SoundAway
> 
> UltraQuiet Panels
> 
> NRC Table
> 
> Frequency (Hz) 1" 2" 4"
> 
> 125 0.08 0.35 0.95
> 
> 250 0.31 0.94 1.30
> 
> 500 0.79 1.32 1.19
> 
> 1000 1.01 1.22 1.08
> 
> 2000 1.00 1.06 1.02
> 
> 4000 0.99 1.03 1.00
> 
> NRC 0.80 1.15 1.15
> 
> 
> I am looking at both the 2" (for reflections), and 4" for bass traps. The finish does already look good, but I may need to still cover with GOM for the WAF.



Yes, Bob Gold's is very informative, but I didn't see the measurements for the panels on there, and didn't know how much the response was affected by making the cotton "rigid". If you have the original PDF, perhaps you could forward it to Bob to add to his site.


Strangely enough, the number quoted for the 4" panels are exactly the same as the 3.5" rolls. To the 2nd decimal point, a coincidence?


Still, except in the lowest frequencies, the 2" panels are outperforming OC703. If you're okay with the look, or willing to spend a little more to custom cover them, it would seem to be a great fiberglass alternative.


----------



## penngray




> Quote:
> Still, except in the lowest frequencies, the 2" panels are outperforming OC703. If you're okay with the look, or willing to spend a little more to custom cover them, it would seem to be a great fiberglass alternative.



Im not sure I understand, you cover all of these products no matter what so they all need custom cover?? In the end they all look the same wont they?


Rolls or panels, does it really matter? You can roll it on a wall and it will stick with 3M adhesive spray, then you just cover over it with GOM.


----------



## penngray




> Quote:
> What was the cost for shipping your purchases?



$60 to ship the ultra cotton rolls (8 strips 24"x94"), $30 to ship 12 1" OC703 panels.



> Quote:
> While the RS meter *can* be used as a mic, it is nearly worthless. You would need to buy a suitable mic to get acceptable results with REW. Many use a Beringer mic. The phantom power reference is in re to some mics needing power to operate and that power is supplied over the signal cable . . remotely . . invisibly . . from either a phantom power supply or, in the case of the poster you quoted, a mixer with builtin phantom power.



bummer....more money to spend







I will have to figure out what to buy now and in a hurry because I wanted to start testing this weekend


----------



## cavchameleon




> Quote:
> Originally Posted by *penngray* /forum/post/13822054
> 
> 
> Im not sure I understand, you cover all of these products no matter what so they all need custom cover?? In the end they all look the same wont they?
> 
> 
> Rolls or panels, does it really matter? You can roll it on a wall and it will stick with 3M adhesive spray, then you just cover over it with GOM.



penngray,


The cotton rolls are actually made for insulation, not attractive. But the cotton panels:

http://www.soundaway.com/acoustic_co...anels_s/91.htm 


Are actually quit attactive already, which is why they already come in colors. They are much stiffer than the rolls (denser) and when mounted with adhesive, may be left as-is without GOM (which I what I may do if my wife accepts the color/look). The pannels have a finished cloth look already, take a look at them.


Also, I'm very sensitive to fiberglass (even if I don't do the install and some fibers leak through the fabric) which is why I was looking for an alternative. The cotton panels are also 'green', made from excess material from making jeans and other clothing, so is more environmentally friendly (something important to me).


As far as covering up, you're right. The material won't matter as far as looks if being covered up.


Thanks!


----------



## cavchameleon




> Quote:
> Originally Posted by *penngray* /forum/post/13822086
> 
> 
> $60 to ship the ultra cotton rolls (8 strips 24"x94"), $30 to ship 12 1" OC703 panels.
> 
> 
> 
> 
> bummer....more money to spend
> 
> 
> 
> 
> 
> 
> 
> I will have to figure out what to buy now and in a hurry because I wanted to start testing this weekend



Here is a fairly good mic (I use this one) for REW:


Behringer ECM8000 Measurement Microphone

http://www.partsexpress.com/pe/showd...number=248-625 

around $50


Very flat respone, here are the specs:

Precise electret condenser measurement microphone

Ultra-linear 15 Hz to 20 kHz frequency response

Well-balanced, true omni-directional pattern

Phantom powered, +15V to +48V

Microphone stand adaptor and windscreen for outdoor measurement included


You will need phantom power to operate. You can use the same brand:

Behringer XENYX 802 Mixer 8-Input 2-Bus
http://www.partsexpress.com/pe/showd...number=248-576 


Or some other (I'm using one from Tascam).


----------



## penngray




> Quote:
> Are actually quit attactive already, which is why they already come in colors. They are much stiffer than the rolls (denser) and when mounted with adhesive, may be left as-is without GOM (which I what I may do if my wife accepts the color/look). The pannels have a finished cloth look already, take a look at them.



ah, I understand now....










btw, thanks for the links for the mic and phantom power. I guess I will need cables too







I have a Notebook with a USB soundcard that I used with my RS SPL meter now I dont have a clue what to hook up.


----------



## cavchameleon




> Quote:
> Originally Posted by *penngray* /forum/post/13822397
> 
> 
> ah, I understand now....
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> btw, thanks for the links for the mic and phantom power. I guess I will need cables too
> 
> 
> 
> 
> 
> 
> 
> I have a Notebook with a USB soundcard that I used with my RS SPL meter now I dont have a clue what to hook up.



Yes, you will need a cable (XLR) to connect the mic to the mixer. Instead of the mixer, you can get a computer interface that already has phantom power onboard and a USB out connection for connection to the computer. This costs a bit more (but you need some type of interface anyway). I use:


TASCAM US-144 USB 2.0 4X4 Audio MIDI Computer Interface, about $150

http://www.musiciansfriend.com/produ...ace?sku=242193 


If you want a cheaper route, you can use the original mixer with phantom power I mentioned above and purchase a separate interface:


Behringer U-CONTROL UCA202 USB-Audio Interface (about $30)
http://www.musiciansfriend.com/produ...ace?sku=702540 


There will be more connections with this option.


btw, this site also sells the mic I mentioned (including all the mixers with phantom power), a great site for any recording gear:
http://www.musiciansfriend.com/produ...one?sku=270400


----------



## pepar

btw, penngray, it is the "electret condenser" design of the aforementioned microphone that needs powered. that design has two charged "plates" in close proximity to each other that produce a signal when vibrating in relation to each other. the charge is maintained by the phantom power.


----------



## pepar

You don't need to buy a mixer to get phantom power. Behringer has a "standalone" model for $20 here . But cavchameleon's USB thingy might kill two birds with one stone.


----------



## cavchameleon




> Quote:
> Originally Posted by *pepar* /forum/post/13822606
> 
> 
> You don't need to buy a mixer to get phantom power. Behringer has a "standalone" model for $20 here . But cavchameleon's USB thingy might kill two birds with one stone.



Acutally, that's a much cheaper option, paired with:

Behringer U-CONTROL UCA202 USB-Audio Interface


The total cost is only $50, not bad! With the mic, a total of $100!


Thanks pepar, I didn't know they had a standalone (I'm used to using large mixer that handle >10 mics at once).


----------



## dbbarron

I find the mixer quite valuable for level adjustments of inputs/outputs of the soundcard and other purposes, for the extra $25 or so, well worth it IMHO.db.


----------



## cavchameleon

Agreed! Forgot to mention that.


----------



## pepar




> Quote:
> Originally Posted by *dbbarron* /forum/post/13822700
> 
> 
> I find the mixer quite valuable for level adjustments of inputs/outputs of the soundcard and other purposes, for the extra $25 or so, well worth it IMHO.db.



Soundcards (and the O/S) have control panel/mixer software to do that.


----------



## cuzed2




> Quote:
> Originally Posted by *pepar* /forum/post/13792344
> 
> 
> I don't think "or" is the right question. Drywall and then treat.



First my Thanks to Terry/Ethan/Pepar on their inputs to my earlier questions.


Actually your responses lead me to seek just a bit more advice on the treatment of my back wall. First a few measurements:


- My screen to back wall distance is 18.5'


- My primary front row seating will be 11' from the screen and 7.5' away from the back wall


- My second row seating will only be 2~3' from the back wall.

*Reducing reflections off the back wall seems to be something I need to take seriously - I need to get considerable absorption on or built into that back wall. I am limited in how much "thickness" I can add.*


Does anyone know if it would be wise (in other words-safe) to entirely skip the drywalled surface and do the following instead?


1) fill between the 2x4 studs with mineral wool

2) Then cover with 1~2" of linacoustic

3) topped off by an appropriate "wife-approved" GOM covering


Again; I am looking to skip the drywall on the theater side of the wall, and use the full wall depth for additional absortion material? (I do aplogize if this a redundant question in this string).


Thanks Again!

Craig


----------



## SPDSpappy




> Quote:
> Originally Posted by *penngray* /forum/post/13820805
> 
> 
> Here are some comparisons of the ultratouch....
> 
> 
> OC703, plain 4" (102mm) on wall 3.0 pcf (48 kg/m3) 0.84 1.24 1.24 1.08 1.00 0.97 1.15
> 
> Rockwool RXL 40 4" (100mm) 4.0 pcf (64 kg/m3) 1.03 1.07 1.12 1.04 1.07 1.08 1.10
> 
> Ultra Touch R-13 3.5" (mm) A 0.95 1.30 1.19 1.08 1.02 1.00 1.15
> 
> 
> 
> From this I think Ultra touch is the best $$$ choice....to get 4" OC you have to buy more!!



I was planning on building my superchunk bass traps w/in the next couple weeks, but now I guess I'll wait to hear how the superchunks made from this stuff work out. I'd much rather use something like this over fiberglass.


----------



## penngray

okay, so Im confused today...


to get measurements of the acoustics in my room I need the following...


Notebook - Own it

REW softare - Have it


Measurement Condenser Microphone -Nady CM100 Reference Measurement Condenser Microphone ?? its cheaper on musicians friend and the Berhinger one is backordered.


Phantom Power Supply - Behringer MICROPOWER PS400 Phantom Power Supply (will it work with the nady mic, I assume it will?


Behringer U-CONTROL UCA202 USB-Audio Interface - this is so I can connect it all to my notebook. WAIT, I have a USB audio device like this from SoundBlaster, wouldnt that work?


Musician friend will ship free if Im over $99....and this stuff does it with a cable or two.


----------



## penngray




> Quote:
> I was planning on building my superchunk bass traps w/in the next couple weeks, but now I guess I'll wait to hear how the superchunks made from this stuff work out. I'd much rather use something like this over fiberglass.



If I can get the measurements done pre bass chunks I can put the chunks in and measure again. Now I have to wait for the equipment so it will be next weekend







I know I need bass chunks no matter what Im just being silly about the pre-treatment measurements because I just want to see the charts before hand.


I dont think there is a question that they utratouch cotton will work. The NRC numbers says it will so I dont doubt it for one minute. If I actually knew about the stuff before I bought the OC703 and rockwool I would have just purchased a large amount the ultratouch stuff. I HATE FIBREGLASS


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13823495
> 
> 
> okay, so Im confused today...
> 
> 
> to get measurements of the acoustics in my room I need the following...
> 
> 
> Notebook - Own it
> 
> REW softare - Have it
> 
> 
> Measurement Condenser Microphone -Nady CM100 Reference Measurement Condenser Microphone ?? its cheaper on musicians friend and the Berhinger one is backordered.
> 
> 
> Phantom Power Supply - Behringer MICROPOWER PS400 Phantom Power Supply (will it work with the nady mic, I assume it will?
> 
> 
> Behringer U-CONTROL UCA202 USB-Audio Interface - this is so I can connect it all to my notebook.
> 
> 
> Musician friend will ship free if Im over $99....and this stuff does it with a cable or two.



you might want to verify that the nady has an individual calibration file with it. no mic is perfectly flat, but if it has been measured and a corresponding file generated then REW will take the mic's output, applies whatever correction is needed to achieve flat and badda bing!


----------



## Ethan Winer




> Quote:
> Originally Posted by *cuzed2* /forum/post/13823155
> 
> *Reducing reflections off the back wall seems to be something I need to take seriously*



Yes.



> Quote:
> if it would be wise (in other words-safe) to entirely skip the drywalled surface and do the following instead?



Yes, that will be excellent acoustically.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *cuzed2* /forum/post/13823155
> 
> 
> Again; I am looking to skip the drywall on the theater side of the wall, and use the full wall depth for additional absortion material? (I do aplogize if this a redundant question in this string).



Craig, the only suggestion I have is to check and see if any fire or building codes impact your plan.


----------



## percept

Hey guys, thanks for the help with my previous questions. I have another to ask...


I'm worried about sound escaping through my window and disturbing my neighbor, whose window is 16 ft. directly across from my window. I'm looking to build a soundproof window plug that doubles as an acoustic panel for my back wall. Here is what i plan to make:


1/2" MDF - Green Glue - 1/2" MDF - 4" OC703


I plan on having the 4" OC703 protrude from the wall while the 1" of MDF fits snugly in the window lined with weatherstripping. This leaves about a 2" airspace between the window and the plug. Would this be effective with regards to soundproofing? Are there any additions I can make that would improve performance? Thanks in advance for the help.


----------



## eugovector




> Quote:
> Originally Posted by *cavchameleon* /forum/post/13822196
> 
> 
> penngray,
> 
> 
> The cotton rolls are actually made for insulation, not attractive. But the cotton panels:
> 
> http://www.soundaway.com/acoustic_co...anels_s/91.htm
> 
> 
> Are actually quit attactive already, which is why they already come in colors. They are much stiffer than the rolls (denser) and when mounted with adhesive, may be left as-is without GOM (which I what I may do if my wife accepts the color/look). The pannels have a finished cloth look already, take a look at them.



Yes, and the panels should be dense enough to just hang on a wall, not have to use adhesive. They say they can be used as ceiling tiles, so they should be able to hang just fine.


----------



## cuzed2

Thanks Ethan!


Now all i have to do is make sure I'm not getting sideways with a safety code somewhere.


Regards,

Craig


----------



## Terry Montlick

Craig,


Yes, definitely check with your local building code department. Once a space is finished and therefore considered "habitable," code generally requires drywall to cover all the wall studs. Plus you should know that you are giving up any possibility of good sound isolation for the room.










Regards,

Terry


----------



## cuzed2

Thanks Terry!


Safety and inspections will be key for me.


As for sound control - Good point. However; this is a bit of an open floor plan and this particular wall defines an adjoining room that is unlikely to be in use when the theater is being used.


----------



## bpape




> Quote:
> Originally Posted by *cavchameleon* /forum/post/13822196
> 
> 
> penngray,
> 
> 
> The cotton rolls are actually made for insulation, not attractive. But the cotton panels:
> 
> http://www.soundaway.com/acoustic_co...anels_s/91.htm
> 
> 
> Are actually quit attactive already, which is why they already come in colors. They are much stiffer than the rolls (denser) and when mounted with adhesive, may be left as-is without GOM (which I what I may do if my wife accepts the color/look). The pannels have a finished cloth look already, take a look at them.
> 
> 
> Also, I'm very sensitive to fiberglass (even if I don't do the install and some fibers leak through the fabric) which is why I was looking for an alternative. The cotton panels are also 'green', made from excess material from making jeans and other clothing, so is more environmentally friendly (something important to me).
> 
> 
> As far as covering up, you're right. The material won't matter as far as looks if being covered up.
> 
> 
> Thanks!



FYI - the 3lb density cotton shown there can be had for considerably less cost.


Bryan


----------



## eugovector




> Quote:
> Originally Posted by *bpape* /forum/post/13848550
> 
> 
> FYI - the 3lb density cotton shown there can be had for considerably less cost.
> 
> 
> Bryan



This is something dense enough that could be used as a panel or ceiling tile, like this , or this is the flexible stuff that must be glued to the wall, or framed in some way?


Do the performance numbers match up with Sound Away's numbers?


Freq - 2" Panels - 3.5 rolls

125 - 0.35 - .95

250 - 0.94 - 1.30

500 - 1.32 - 1.19

1000 - 1.22 - 1.08

2000 - 1.06 - 1.02

4000 - 1.03 - 1.00

NRC - 1.15 - 1.15


And could you provide a link (or pm me and I'll link it.)?


----------



## penngray




> Quote:
> FYI - the 3lb density cotton shown there can be had for considerably less cost.



really, could we have a link? Not that it matters to me now, I have more then enough material to use in two HT rooms


----------



## nathan_h




> Quote:
> Originally Posted by *bpape* /forum/post/13848550
> 
> 
> FYI - the 3lb density cotton shown there can be had for considerably less cost.
> 
> 
> Bryan



Count me in as another interested in a source.


I have 10 GIK panels in my room (you may recall we talked a couple of times) but I have a few "cavities" that I'd love to stuff with some bulk materials and cotton is more appealing to me for that.


----------



## bpape

The 3lb density panels you showed above are still floppy somewhat but considerably denser than the UltraTouch. The pieces I was referring to are the 3lb panels.


Bryan


----------



## dbbarron

Bump...(Looking to finalize the panels and fabricate).....


From a few weeks ago after I posted some room response data, Terry commented:



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13734166
> 
> 
> Hi db,
> 
> 
> I'd say that your reverberations times in the octave bands 125 Hz and 250 Hz are a bit too high relative to the higher frequency octave bands. These higher frequency octave band reverberation times are not too low on an absolute scale, but too low on a scale relative to the 125 Hz and 250 Hz octave bands. This unevenness can make the room sound too dead. As for the 63 Hz octave band, reverberation time measurement at these low frequencies is too unreliable in small rooms to be useful.
> 
> 
> But since your upper frequencies are fine, you just need more absorption at the highly treatable 125 Hz and 250 Hz octave bands. I recommend either DIY bass traps, as described in this forum and on http://forum.studiotips.com/viewtopic.php?t=535 , or ready-made bass traps by forum members RealTraps or GIK Acoustics.
> 
> 
> Regards,
> 
> Terry



I have since then doubled the sidewall linacoustic to 2" in hopes of absorbing some lower frequencies without further absorbing the higher frequencies. I also treated the ceiling first reflection point.


Data is below:


First, measurements of impulse response in the room with 1" sidewall linacoustic and no ceiling treatement:











Second, with ceiling (first reflection point) and 2" sidewall treatement











Now RT60: Red is no treatment, green is with one inch sidewall treatment and yellow is with two inch treatment. These are 1 octave averages, with 1/3 octave averaging the 2" graph is lower than the 1" as expected except for one errant point which sets off the 1 octave average.











Lastly, waterfalls; first no treatment











Second, with 1" sidewall treatement











Third with 2" sidewall treatment











I think, to Terry's point, I have addressed the 125-250hz region and ceiling reflection as (separately) suggested. The sound is good, but subjectively, now a bit thin in the mid bass. Will have to think about this a bit.


The big question....am I there yet?


Comments welcome..


db


----------



## eugovector




> Quote:
> Originally Posted by *bpape* /forum/post/13857400
> 
> 
> The 3lb density panels you showed above are still floppy somewhat but considerably denser than the UltraTouch. The pieces I was referring to are the 3lb panels.
> 
> 
> Bryan



Are they more/less floppy than 703?


----------



## bpape

More. Even the 6lb cotton board isn't as stiff as 703 boards. Not sure how they're saying this will work in ceiling grids. I work with the cotton material all the time and I don't see how that would fly.


Bryan


----------



## eugovector




> Quote:
> Originally Posted by *bpape* /forum/post/13864817
> 
> 
> More. Even the 6lb cotton board isn't as stiff as 703 boards. Not sure how they're saying this will work in ceiling grids. I work with the cotton material all the time and I don't see how that would fly.
> 
> 
> Bryan



Very good to know. Thank you.


----------



## Dan Woodruff

I have a quick question about sand for those of you who may know.


When building your stage, what type of sand are you guys using to fill it? All

I seem to be able to find locally is play sand (child's sand box).


----------



## Terry Montlick

Dry play sand is the stuff.


- Terry


----------



## notoriousmatty

Im wondering what size and how many acousitc cotton panels I need for 10x12 room. Im sitting in my bed right on the back wall and have listening fatigue quick because of the hollowness of the room. Thanks.


----------



## eugovector




> Quote:
> Originally Posted by *notoriousmatty* /forum/post/13903760
> 
> 
> Im wondering what size and how many acousitc cotton panels I need for 10x12 room. Im sitting in my bed right on the back wall and have listening fatigue quick because of the hollowness of the room. Thanks.



It's tough to give a general answer with as little information as we have about your room. Post a layout (I like using "room arranger", google it) and maybe some pictures. Even then it will still be best if you do some tests using Room EQ Wizard or something similar.


----------



## Mupi

well I tried the bass trap using 2'' OC 703.


I stacked up to some 6ft as shown in the picture.

Earlier I had just placed a single 2'' 2x4 panel at the

corner.


I am surprised to see that a stack of 6' wedges didnt

make any difference at all compared to a single 2x4 panel.


Also, either with the stack or a single panel, there was not much

change in the peaks and nulls. I also have 2x4 panel at the other 2 corners

in my room.


I was just wondering if I am doing anything wrong for not seeing

any improvement.


----------



## eugovector




> Quote:
> Originally Posted by *Mupi* /forum/post/13907955
> 
> 
> well I tried the bass trap using 2'' OC 703...



Do you have pics of your measurement graphs. There are a number of reasons why you may not be seeing the results you're hoping for:


1) The frequency you're looking to affect is too low.

2) 1 stack is not enough treatment to make a big difference

3) Treatment is in the wrong place


I'm not saying these are the case, I'm just saying that it's a possibility.


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/13907988
> 
> 
> Do you have pics of your measurement graphs. There are a number of reasons why you may not be seeing the results you're hoping for:
> 
> 
> 1) The frequency you're looking to affect is too low.
> 
> 2) 1 stack is not enough treatment to make a big difference
> 
> 3) Treatment is in the wrong place



My money's on #2.


----------



## chrhon

FYI I am totally new to acoustic treament. I've skimmed through the thread but have not read in detail - sorry if I bring something up that has been covered.


Quick question... I have some 1.5" deep Canvas "paintings" (movie posters printed on canvas actually - pm me if you want the details) for use in our combination living room / home theater. I ordered the 1.5" deep ones over the shallow ones so that I could have some level of acoustical treatment that was wife approved (the only pure sound treatment thing she has approved is some bass traps from acoustical solutions in the sound suede - still trying to decide how much of those I want to do because money is tight right now). I also have some tapestries which I am thinking of putting wall panels behind.


My question is what would be the best material to stuff these canvas paintings with? (keeping in mind they are only 1.5" deep) Just fiberglass from home depot or should I look at ordering some special materials? (edit to add: These are on the side walls)


----------



## percept

fiberglass from home depot won't be dense enough.


----------



## chrhon

Any recommendations of something readily available? (or something inexpensive online)


Right now I am having the trouble that for acoustic treatment stuff the shipping costs as much or more than the items (thats one of the problems with the "wife approved" sound suede from acoustical solutions, the shipping is as much as the treatments!)


----------



## pepar




> Quote:
> Originally Posted by *chrhon* /forum/post/13910514
> 
> 
> Any recommendations of something readily available? (or something inexpensive online)
> 
> 
> Right now I am having the trouble that for acoustic treatment stuff the shipping costs as much or more than the items (thats one of the problems with the "wife approved" sound suede from acoustical solutions, the shipping is as much as the treatments!)



The way around that is to source the material locally from an HVAC distributor and make your own treatments.


----------



## Mupi




> Quote:
> Originally Posted by *pepar* /forum/post/13909166
> 
> 
> My money's on #2.




I have 2x4 panels at all other corners in my room and a 6' stack at one corner that is near the sub. I also have put panels at 1st reflection points. I used up all 12 panels that came in the box. I really dont see much improvement in the low end. I have attached the curves. Like I said I see the peaks at the same frequencies as before. They have not changed much at the low end. The peak at 142.5Hz has come down a lot but the sound is still as boomy as before because the rest of the curve is still as bad as before with peaks and nulls.


In fact I got better results with just the BFD (DSP1124P) and no panels.

I was ridiculed at the subwoofer forum for just trying the BFD and not the acoustic treatment.


Right now my sub (Sunfire Junior) can only go up to some 90Hz. It is rated as 22-100Hz but rolls off at 90 or so. So I cant control the peaks over 90 using the BFD. I was planning to try the SVS SB10 as it goes up to 200hz. I can set the cross over at 150 or 180hz on my receiver. But I was ridiculed for even having this idea of setting a high cross over and was asked to try the bass traps. Apparently the bass traps dont seem to be working as miraculously as I expected.


BTW the FR is not in log scale. I guess it doesnt matter for display purposes. I use the REW software which gives in log scale but I dont know how to import 2 measurements into REW. So I just used Excel.


My speakers are Klipsch RB81. Receiver is Yamaha RX-V795a (which has a fixed cross over at 90Hz). DVD player OPPO 980H (mainly for 2ch music).

I do have the Onkyo 705 but I really dont see any improvement in sound with the onkyo. Infact my 7 yr old Yamaha RX-V795 sounds better than the Onkyo. Anyway... that is a different story.


----------



## Mupi

just ignore the tall black frames. That is something I had built for my

HT and it is not part of the room treatment.


----------



## pepar




> Quote:
> Originally Posted by *Mupi* /forum/post/13912439
> 
> 
> I have 2x4 panels at all other corners in my room and a 6' stack at one corner that is near the sub. I also have put panels at 1st reflection points. I used up all 12 panels that came in the box. I really dont see much improvement in the low end. I have attached the curves. Like I said I see the peaks at the same frequencies as before. They have not changed much at the low end. The peak at 142.5Hz has come down a lot but the sound is still as boomy as before because the rest of the curve is still as bad as before with peaks and nulls.
> 
> 
> In fact I got better results with just the BFD (DSP1124P) and no panels.
> 
> I was ridiculed at the subwoofer forum for just trying the BFD and not the acoustic treatment.
> 
> 
> Right now my sub (Sunfire Junior) can only go up to some 90Hz. It is rated as 22-100Hz but rolls off at 90 or so. So I cant control the peaks over 90 using the BFD. I was planning to try the SVS SB10 as it goes up to 200hz. I can set the cross over at 150 or 180hz on my receiver. But I was ridiculed for even having this idea of setting a high cross over and was asked to try the bass traps. Apparently the bass traps dont seem to be working as miraculously as I expected.



Focusing only on the corner treatments - very little bass absorption takes place with your FRP panels - single 2x4 panels across the corners are nowhere near enough. Floor-to-ceiling 2x4 panels mounted like this would be better. And one 6' stack of triangles in one corner is, likewise, not enough. The fully filled triangle corner trap style goes deeper than 2" thick panels crosswise (with space behind them; try two corners with that style floor to ceiling. Check the link in my sig for an idea of where you need to head to get results. They should not have dissed you, but bass traps are definitely the way to go. Electronic correction corrects - at best - for one listening position whereas traps improve everywhere. Electronic correction can only be used to reduce peaks. Room nulls cannot be EQ'd out. Bass traps reduce the peaks and the nulls.


Post info on your room size and shape, too.


----------



## penngray




> Quote:
> In fact I got better results with just the BFD (DSP1124P) and no panels.
> 
> I was ridiculed at the subwoofer forum for just trying the BFD and not the acoustic treatment.



You have to do both to create the best sub sound, Did you Eq those peaks yet? Honestly, treatment will not do much in solving those peaks and I dont think anyone ever said it would in that thread.


----------



## bpape

The chunks will reach lower but are no more surface area than a panel straddling. You'll need to do at least the other symmetric corner and try going higher.


Treatment can deal with both frequency and decay time issues. Your waterfalls clearly show improvement in decay time but in the bottom end, it's still just not enough thickness in enough places.


Some of the frequency abberations are likely due to a combination of seating position, speaker position and sub position along with potential mismatch in phase settings from sub to mains.


EQ deals only with the frequency domain and can be used after properly treating a room and setting up the speakers/sub/seating correctly to minimize those issues. You can EQ down the last few stubborn peaks to smooth things a bit. It can also be helpful for VERY low frequencies which are very stubborn to deal with via treatment due to physical size limitations.


Bryan


----------



## penngray




> Quote:
> It can also be helpful for VERY low frequencies which are very stubborn to deal with via treatment due to physical size limitations.



Yes, that was my point above actually, I was only making a point that very low frequencies need EQing no matter what you have in treatment....I have learned that a 25 Hz or 40Hz wavelength is really large and to actually handle that with treatment is physically impossible in many rooms.


----------



## Mupi




> Quote:
> Originally Posted by *bpape* /forum/post/13915128
> 
> 
> The chunks will reach lower but are no more surface area than a panel straddling. You'll need to do at least the other symmetric corner and try going higher.
> 
> 
> Treatment can deal with both frequency and decay time issues. Your waterfalls clearly show improvement in decay time but in the bottom end, it's still just not enough thickness in enough places.
> 
> 
> Some of the frequency abberations are likely due to a combination of seating position, speaker position and sub position along with potential mismatch in phase settings from sub to mains.
> 
> 
> EQ deals only with the frequency domain and can be used after properly treating a room and setting up the speakers/sub/seating correctly to minimize those issues. You can EQ down the last few stubborn peaks to smooth things a bit. It can also be helpful for VERY low frequencies which are very stubborn to deal with via treatment due to physical size limitations.
> 
> 
> Bryan




I guess my pictures are misleading. I dont have symmetric corners at the

front. I had a picture of the same corner with a 2x4 panel and a 6' stack.


I will try to fill the stack all the way to the ceiling and also try full height

2x4 panels on the other corners. It was really difficult to cut the panels using that slicer in pepar's page. I bought the same thing.


May be I need to use a thickner wooden piece as pepar did so that the slicer will go all the way through the panel. it took me some 5 hrs or so to make that 6' stack !


----------



## Mupi




> Quote:
> Originally Posted by *penngray* /forum/post/13915019
> 
> 
> You have to do both to create the best sub sound, Did you Eq those peaks yet? Honestly, treatment will not do much in solving those peaks and I dont think anyone ever said it would in that thread.



yep with the BFD (DSP1124P) I was able to EQ the peaks. I tried the FBQ2496 as it is supposed to be better but looks like mine is defective because it lowers the entire output even if I set a genative gain at one frequency. I also verified this using full range signal. Anyway...I will post that in the BFD thread as it is out of topic here.


----------



## pepar




> Quote:
> Originally Posted by *Mupi* /forum/post/13916099
> 
> 
> I guess my pictures are misleading. I dont have symmetric corners at the
> 
> front. I had a picture of the same corner with a 2x4 panel and a 6' stack.
> 
> 
> I will try to fill the stack all the way to the ceiling and also try full height
> 
> 2x4 panels on the other corners. It was really difficult to cut the panels using that slicer in pepar's page. I bought the same thing.
> 
> 
> May be I need to use a thickner wooden piece as pepar did so that the slicer will go all the way through the panel. it took me some 5 hrs or so to make that 6' stack !



No doubt it is a wrist-killer, but in 5 hours I did about 4x what you did. The knife dulls right away and from then on it's muscling through it. It was good that I use my right wrist regularly.


----------



## Jason Pancake

Planning on putting up my Linacoustic and GOM this weekend in my 16'x20' theater. I'm planning on putting Linacoustic on the entire front wall and on the bottom half of the rest of the room to just above ear level. The big question I have is: Poly or no poly on the top half of the room?

Photos of the room


----------



## pepar




> Quote:
> Originally Posted by *Jason Pancake* /forum/post/13916780
> 
> 
> Planning on putting up my Linacoustic and GOM this weekend in my 16'x20' theater. I'm planning on putting Linacoustic on the entire front wall and on the bottom half of the rest of the room to just above ear level. The big question I have is: Poly or no poly on the top half of the room?
> 
> Photos of the room



Poly?


It is sooo easy to overdeaden small theaters. My walls are walls are painted plaster above the wall carpet. Check the site linked in my sig.


BTW, some nice dust on your camera lens!


----------



## SPDSpappy




> Quote:
> Originally Posted by *penngray* /forum/post/13823515
> 
> 
> If I can get the measurements done pre bass chunks I can put the chunks in and measure again. Now I have to wait for the equipment so it will be next weekend
> 
> 
> 
> 
> 
> 
> 
> I know I need bass chunks no matter what Im just being silly about the pre-treatment measurements because I just want to see the charts before hand.
> 
> 
> I dont think there is a question that they utratouch cotton will work. The NRC numbers says it will so I dont doubt it for one minute. If I actually knew about the stuff before I bought the OC703 and rockwool I would have just purchased a large amount the ultratouch stuff. I HATE FIBREGLASS



Hey penngray, any updates on this? I have my front wall mostly treated, now I'm just waiting to do the superchunks.


----------



## penngray




> Quote:
> Hey penngray, any updates on this? I have my front wall mostly treated, now I'm just waiting to do the superchunks.



The pre-treatment measurements are done now and this weekend Im building my bass traps.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13930655
> 
> 
> The pre-treatment measurements are done now and this weekend Im building my bass traps.


*Very anxious* to see the before and after measurements!!!


----------



## penngray




> Quote:
> Very anxious to see the before and after measurements!!!



me too!! I did three different Mic placements because they all had different results. My room design isnt perfect and my Subs are "locked" in certain positions so there are limits to my success










My whole HT build thread is VERY OUTDATED so I have to update it with lots of pics and charts. I will do so this weekend.


----------



## allredp




> Quote:
> Originally Posted by *penngray* /forum/post/13931756
> 
> 
> me too!! I did three different Mic placements because they all had different results. My room design isnt perfect and my Subs are "locked" in certain positions so there are limits to my success
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> My whole HT build thread is VERY OUTDATED so I have to update it with lots of pics and charts. I will do so this weekend.



Cool! Looking forward to your results/impressions.


I'm in the middle of getting my REW outfit set up and then I'm ready to work over similar before/after graphs and charts.


Good luck...


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13931756
> 
> 
> me too!! I did three different Mic placements because they all had different results. My room design isnt perfect and my Subs are "locked" in certain positions so there are limits to my success



Most are. Mine certainly are. IMO, that's where SSC traps come in, if one is able to incorporate them into one's theater. They are not easy to hide.


Do you know about the upcoming AVS AS-EQ1 ?


----------



## penngray




> Quote:
> Do you know about the upcoming AVS AS-EQ1?



Nope, thats a pretty cool product...if its cheap enough I will own it







but I already have the BFD DSP1124p and the eD EQ.2, add to that two velodyn SC-1250s that do EQing....lol. I doubt I need all those!


----------



## penngray

When running REW to get my room measurements do I only look at Waterfalls up to around 1K Hz? then beyond that use RT60?


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13933030
> 
> 
> Nope, thats a pretty cool product...if its cheap enough I will own it
> 
> 
> 
> 
> 
> 
> 
> but I already have the BFD DSP1124p and the eD EQ.2, add to that two velodyn SC-1250s that do EQing....lol. I doubt I need all those!



Projected at $750. What it does differently than what must now be called "conventional" electronic correction (EQ) is set filters in both the frequency domain and the time domain. Plus, this unit "does" two separate and independent sub channels. It phases them, sets the levels and then applies the Audyssey filters I mentioned. Even if you could EQ two separate sub channels, the time domain stuff is new and proprietary. If your BFD is playing checkers, Audyssey-powered units (AVRs and pre/pro, and now this) are playing chess . . _*3D chess*_.


- Jeff


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13933041
> 
> 
> When running REW to get my room measurements do I only look at Waterfalls up to around 1K Hz? then beyond that use RT60?



The waterfalls are a visualization of decay. RT60 is easy to determine from a waterfall; simply look at the time it takes for the level to drop 60 dB.


----------



## penngray

Any information on Tube traps ???

http://www.acousticsciences.com/pricing.htm 


It seems this is the only way to really control the sub 80Hz frequencies. Im planning on building triangle corner traps but if they are not as effect as tube traps then maybe I should build tube traps.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/13934873
> 
> 
> Any information on Tube traps ???
> 
> http://www.acousticsciences.com/pricing.htm
> 
> 
> It seems this is the only way to really control the sub 80Hz frequencies. Im planning on building triangle corner traps but if they are not as effect as tube traps then maybe I should build tube traps.



What is the first column - the frequency? Do they go to that or are they tuned to that? If the latter, then they are not broadband like SuperChunk traps.


----------



## Terry Montlick




> Quote:
> Originally Posted by *penngray* /forum/post/13934873
> 
> 
> Any information on Tube traps ???
> 
> http://www.acousticsciences.com/pricing.htm
> 
> 
> It seems this is the only way to really control the sub 80Hz frequencies. Im planning on building triangle corner traps but if they are not as effect as tube traps then maybe I should build tube traps.



This is a price list. It can say anything. The manufacturer can claim anything. Ask them for the *complete* ASTM C-423 lab reports on these products. These are the standardized, independent tests for sound absorption over a wide range of frequencies. If these cannot be furnished, I would not even consider buying the product.


Regards,

Terry


----------



## Ethan Winer

Terry, just to be clear, ASC is a respected (by me) company who has been around for a long time, and their products do work. Maybe not the skinny little tubes and quarter-rounds, but their large and expensive 20-inch full-round model definitely works. Bang for the buck is a different issue, but the performance is there on the largest model.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/13938763
> 
> 
> Terry, just to be clear, ASC is a respected (by me) company who has been around for a long time, and their products do work. Maybe not the skinny little tubes and quarter-rounds, but their large and expensive 20-inch full-round model definitely works. Bang for the buck is a different issue, but the performance is there on the largest model.
> 
> 
> --Ethan



Of course, I know that Ethan. But if they are going to put Hz numbers on their tube traps, the burden of objective proof is on them. They didn't have to give them any specs at all. But since they are, well, ...


Art is a big boy. He should be able to handle such a request.


Regards,

Terry


----------



## Dennis Erskine

No lab test results....no buy. A gem of wisdom for an product claiming acoustical (or other magic) properties.


----------



## yngdiego




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/13939847
> 
> 
> No lab test results....no buy. A gem of wisdom for an product claiming acoustical (or other magic) properties.



+1 on that. Without hard facts, anyone can claim just about anything. Specially at their steep prices, I want scientific proof they do what they claim.


----------



## AnthemAVM

I had used the GIK Tri Traps in my family room, had 4 of them. Do to a change in furniture I had to let them go. I was thinking of using the RPG Modex traps in the top of the corners.


Any thoughts on the RPG Modex Bass Traps?


Thanks


----------



## Terry Montlick

The RPG Modex traps are tuned membrane absorbers. They are fabricated and sold for specific center frequency bands. They are meant to absorb over relatively narrow frequency regions, and are not wide-band like the GIK traps.


You could use multiple Modex traps tuned to cover multiple adjacent frequency bands. RPG purposely varies the tuning within the specific band. But this is very expensive. You'd need *many* of these costly devices to achieve this.


On the subject of testing, RPG provides absorption data on their bass traps, measured in their own facility by the impedance tube method. But I've never seen any ASTM C-423 reverberation room measurements for Modex absorbers. So we don't actually know how the absorption coefficients, limited to 1.0 by virtue of the impedance tube method, translate into sabins of reverb room absorption!


Regards,

Terry


----------



## AnthemAVM




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13942105
> 
> 
> The RPG Modex traps are tuned membrane absorbers. They are fabricated and sold for specific center frequency bands. They are meant to absorb over relatively narrow frequency regions, and are not wide-band like the GIK traps.
> 
> 
> You could use multiple Modex traps tuned to cover multiple adjacent frequency bands. RPG purposely varies the tuning within the specific band. But this is very expensive. You'd need *many* of these costly devices to achieve this.
> 
> 
> On the subject of testing, RPG provides absorption data on their bass traps, measured in their own facility by the impedance tube method. But I've never seen any ASTM C-423 reverberation room measurements for Modex absorbers. So we don't actually know how the absorption coefficients, limited to 1.0 by virtue of the impedance tube method, translate into sabins of reverb room absorption!
> 
> 
> Regards,
> 
> Terry



Terry,


Thanks, do you know of any bass traps about the size of modex?


----------



## Terry Montlick




> Quote:
> Originally Posted by *AnthemAVM* /forum/post/13942690
> 
> 
> Terry,
> 
> 
> Thanks, do you know of any bass traps about the size of modex?



Yes. One is the Studiotips SuperChunk:
http://forum.studiotips.com/viewtopic.php?t=535 


Another is the Auralex MegaLENRD (not pretty, but effective):
http://www.sweetwater.com/store/detail/LENRD4PUR/ 


Test data for both are here:
http://forum.studiotips.com/viewtopic.php?t=536 


The SuperChunk is a DIY solution, but I would venture a guess that you could get someone on the AVS forum to build and ship a version to you, covered in nice Guilford fabric, for a fraction of the price of the RPG Modex Corners!










Regards,

Terry


----------



## armstrr

loose fill cellulose insulation for superchunks.


i am about to insulate my basement. i used a product called insulweb which is glued and stapled to the studs. a 4" slit is made in the insulweb "fabric" as required and a hose inserted into the cavity through which cellulose is blown. unlike loose fill cellulose in attics, the object is to achieve a cellulose density of 3.5lb/cubic foot. this is recommended to insure no settling.


my thought is i could build "nooks" into the corners covered with insulweb and then blow the insulation in. i could later build fabric panels to pretty it up.


does anyone see this as viable? i guess the question is how 3.5lb/cubic foot cellulose compares to the traditional dense fiberglass products normally used.


any ideas guys? if this works, it would likely be the cheapest way to do these as long as you get more than 20-25 bags (lowes lends their blower free is you get a minimum amount).


thanks for your replys!!


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/13942969
> 
> 
> Test data for both are here:
> http://forum.studiotips.com/viewtopic.php?t=536



Since we're being sticklers for accurate and valid test data, the "data" on that page is not certified and suffers from two big problems:


1) ASTM tests require at least 60 square feet of surface area for reliable results, and those tests had less than one third that. Just because a test is performed in a certified lab does not mean the test is legitimate.










2) ASTM has no standard for corner mounted traps. They should have this! But they don't. Yet. I'm sure you saw my article in Sound and Vibration magazine addressing the failure of the current test standards, but for the benefit of others who may be interested here's the link:

http://www.realtraps.com/art_testing.htm 


BTW, I agree that Art Noxon (ASC head) is a big boy, and I agree with Dennis that data is what separates snake oil from legitimate products. But I didn't want people here who have not heard of ASC to think ASC is suspect. (Yikes, I can't believe I'm supporting the reputation of a direct competitor! But what's fair is fair...)


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *armstrr* /forum/post/13943207
> 
> 
> loose fill cellulose insulation for superchunks.
> 
> 
> i am about to insulate my basement. i used a product called insulweb which is glued and stapled to the studs. a 4" slit is made in the insulweb "fabric" as required and a hose inserted into the cavity through which cellulose is blown. unlike loose fill cellulose in attics, the object is to achieve a cellulose density of 3.5lb/cubic foot. this is recommended to insure no settling.
> 
> 
> my thought is i could build "nooks" into the corners covered with insulweb and then blow the insulation in. i could later build fabric panels to pretty it up.
> 
> 
> does anyone see this as viable? i guess the question is how 3.5lb/cubic foot cellulose compares to the traditional dense fiberglass products normally used.



This density of cellulose has roughly the same acoustic resistivity as OC 705 fiberglass. I would therefore expect it to perform about as well in this application.


Regards,

Terry


----------



## beatboy77

I have read through this thread and cannot find an answer to my questions.


1. How do you attach the Linacoustic to the drywall?


2. How do you attach the GoM to the Linacoustic?


~Josh


----------



## Mupi

ok I added 703 to the 3 corners in my room.

I really see no improvement in the peaks/nulls.


May be it sounds a little better than before but

that may be psychological.


To be honest this has been just a waste of time and effort.

I dont care much about the money as I spent just under $200

for the 703 and other supplies. But considering very negligible

impact it had to the curve I feel this has all been just a waste of

time. Sorry I just dont buy the argument that I have to go all the way to the

ceiling. Now I have upto some 7ft at all 3 corners and going another 2 feet is not going to make the curve flat.


I am sure I can make the curve a lot better using the BFD FBQ2496 without any of the 703. Sure it is only for one position. I dont care much about other positions as I am single 

So only my seating position matters. I guess I will try the SVS SB12 or SB10 as it can go upto some 200Hz (pretty flat ) and then set the cross over very high and EQ using FBQ2496. Then I dont

have to worry about my mains. Now my sub can go only up to some 90Hz and the rest

of the curve is due to the mains/fronts. In fact the SVS SB12 or SB10 can go up to 300Hz without significant drop. So I could set the cross over at 200hz which I guess is as high as it gets on any AVR.


I will go against convensional wisdom that subs are meant to be under 80Hz. Now I am going my convensional wisdom and it sucks. I dont think it can get any worse. Like I have mentioned in other posts, I can always move the sub to the center if I find it directional when I set the crossover high. Other than becoming directional I really dont see any drawbacks of using a high cross over on the sub.


People just keep arguing but how many people here or in the subwoofer forum have used a sub like SVS SB12 (that can go as high as 200-300Hz ) with a high cross over to see how it sounds before just denouncing it as a bad idea. Now I know that 703 wasnt a good idea so I shall try the other route and see what it has to offer. I can always return the sub as SVS offers a 60-day return.


BTW: just ignore that black frame and the fact that the FR is not in log scale. I made those

black frames for the screen that I had in that recess. I havent found a better place

to move the frames since I moved the screen to the wall where the other corner is.


----------



## r_pogo

My new media room is nearing completion. After dong quite a bit of testing and listening (and contrary to most comments here) I have sort of settled on a modified live end - dead end design using DIY panels. Front half of the room is almost totally dead down to about 250hz, and the back half has a bunch of bass traps to attenuate the 250 and below but is quite live above 250HZ. I built the speakers with a matching 250 HZ crossover to the woofers and will eventually tune the port frequency rolloff to match the room response and tidy up any leftovers with a little EQ if required. Yes, a bit tricky. I'm still working on the front wall so the final design is not quite done.


My source is mostly CDs through a Behringer Uultracurve (temporary, I hope) then to a Yamaha DSP3000 (COAX) which does the final D-A for the L&R mains, L&R front surrounds, and L&R rear surrounds. Will not use a center channel with the Yamaha. The Yamaha recommends a "dead" room but I find it a little too creepy, hence the live back end, at least for the higher frequencies. The final consideration is 5.1 decoding by a Sony E800 which is my last can of worms The outputs of Yamaha and the Sony will be switched to the amps. Now I gotta figure what to do about the center channel (already got the speaker built.)


Not mentioned much in all the discussions is how the dead end cuts left-right crosstalk to the listener (up close you even get the headphone effect.) This apparently focuses the mono image in a very surprising way. The speakers are about ten feet apart and the center mono image is distinctly about three to four feet wide and dead center, and solid as a rock. Seating position seems less critical - moving right to left does not seem to change the apparent center much. The mono image seems more natural and in the same plane as the six foot wide projection screen. I am beginning to like this effect, especially for dialog. At first listen it seems more theater like than a dedicated center channel speaker. I and am considering ditching the center channel speaker.


Has anybody observed this in their setup? If so I'd love to know more. Comments? Opinions? Speculations?


----------



## penngray

I just stacked my Rockwool 60 panels in all corners 12" thick to do a simple test.




No treament waterfall (ignore greater than 300 Hz, I forgot to set the ranges)











Initial simple corner bass treatment











Current Sub FR plot











Some questions, can I really control the sub 80Hz stuff? Do I really care? Its sounding pretty good, I like the huge compression I feel and the fact that I can shake the room with my dual subs










Im actually going to install all treatments this week.....FINALLY!!!


----------



## Mupi




> Quote:
> Originally Posted by *Mupi* /forum/post/13991116
> 
> 
> ok I added 703 to the 3 corners in my room.
> 
> I really see no improvement in the peaks/nulls.
> 
> 
> May be it sounds a little better than before but
> 
> that may be psychological.
> 
> 
> To be honest this has been just a waste of time and effort.
> 
> I dont care much about the money as I spent just under $200
> 
> for the 703 and other supplies. But considering very negligible
> 
> impact it had to the curve I feel this has all been just a waste of
> 
> time. Sorry I just dont buy the argument that I have to go all the way to the
> 
> ceiling. Now I have upto some 7ft at all 3 corners and going another 2 feet is not going to make the curve flat.
> 
> 
> I am sure I can make the curve a lot better using the BFD FBQ2496 without any of the 703. Sure it is only for one position. I dont care much about other positions as I am single
> 
> So only my seating position matters. I guess I will try the SVS SB12 or SB10 as it can go upto some 200Hz (pretty flat ) and then set the cross over very high and EQ using FBQ2496. Then I dont
> 
> have to worry about my mains. Now my sub can go only up to some 90Hz and the rest
> 
> of the curve is due to the mains/fronts. In fact the SVS SB12 or SB10 can go up to 300Hz without significant drop. So I could set the cross over at 200hz which I guess is as high as it gets on any AVR.
> 
> 
> I will go against convensional wisdom that subs are meant to be under 80Hz. Now I am going my convensional wisdom and it sucks. I dont think it can get any worse. Like I have mentioned in other posts, I can always move the sub to the center if I find it directional when I set the crossover high. Other than becoming directional I really dont see any drawbacks of using a high cross over on the sub.
> 
> 
> People just keep arguing but how many people here or in the subwoofer forum have used a sub like SVS SB12 (that can go as high as 200-300Hz ) with a high cross over to see how it sounds before just denouncing it as a bad idea. Now I know that 703 wasnt a good idea so I shall try the other route and see what it has to offer. I can always return the sub as SVS offers a 60-day return.
> 
> 
> BTW: just ignore that black frame and the fact that the FR is not in log scale. I made those
> 
> black frames for the screen that I had in that recess. I havent found a better place
> 
> to move the frames since I moved the screen to the wall where the other corner is.



here is the before-after FR


----------



## allredp

Are your before and after reverse labeled? If not, then stick with the before, eh?!


----------



## Mupi




> Quote:
> Originally Posted by *allredp* /forum/post/13993513
> 
> 
> Are your before and after reverse labeled? If not, then stick with the before, eh?!



nope the labels are correct. "After" is the one with bad nulls.

yep like I said all those effort was just a waste of time.


The only thing 703 could do is probably give me lung cancer!


I guess I am going to pursue the EQ route using the SVS SB12 and FBQ2496


I am going to ask my coworker who is building his HT to come get

all the 703 crap out of my living room before they find their way

into my lungs 


BTW: has anyone been concerned that having all that fiber glass stuff in the room is a health hazard? The fibers dont come out or spread unless the panels are rubbed or cut and they are no finer than the dust from the carpets. I dont want to spend several hundread bucks on GOM to cover up all the 703 stuff. I would rather dump them in trash in those plastic bags I got from the place where I bought them.


----------



## penngray




> Quote:
> I dont want to spend several hundread bucks on GOM to cover up all the 703 stuff. I would rather dump them in trash in those plastic bags I got from the place where I bought them.



You have to cover 703 with something, it should never be left exposed.


----------



## r_pogo

I used dense 3/4" thick polyester batt (comes in a big roll for upholstery and bedding) over the glass in my panels -- looks like air filter material. It provides a mechanical barrier against disturbing the glass, including air flowing from the AC/heat vents across the surface. Because it has low density compared to glass it probably has very little acoustic effect but it might cut high frequency reflections at shallow angles where glass might be a little reflective. It is white so it will show through dark color fabric. Looks OK under light beige Wallymart burlap.


----------



## Mupi




> Quote:
> Originally Posted by *penngray* /forum/post/13994448
> 
> 
> You have to cover 703 with something, it should never be left exposed.



is it due to health reasons?


----------



## Mupi

Considering the fact that they didnt make a big difference and that it may be a health hazard if left uncovered, I am going to get rid of them. My coworker is not ready with his HT for him to take them. So I am going to just dump them in trash in the plastic bags they came in.


Total 24 2'' panels. 8 of them are still uncut. I might keep 3 to cover the

fire place as it seems to insulate the fire place from cold draft (I dont use the fire place). Only for those 3 I will add some cheap cover.


I live in Detroit metro. If anyone is interested in taking them let me know.

I am not asking for a lot of money. May be $25 to cover the cost to wrap those 4 panels with some cloth/frame.

They are well cut. oh yeah you can take the slicer too. I had of them.

One got very dull so I trashed it. Other one is new and I only cut some 5-6 panels using that.


I may not wait too long. The sooner I get rid of them the lower the risk of getting any health issues. I may even start dumping them in the next couple of days, keeping only 3 penals in the garage. I am not sure if waste management will have any issues if I dump them in my drive way. Will test it first with a few panels 


And for those of you trying to put the 703: Good luck and god bless


----------



## eugovector




> Quote:
> Originally Posted by *Mupi* /forum/post/14000237
> 
> 
> Considering the fact that they didnt make a big difference and that it may be a health hazard if left uncovered, I am going to get rid of them. My coworker is not ready with his HT for him to take them. So I am going to just dump them in trash in the plastic bags they came in.



Woah, don't trash 'em dude. Someone here will take them. Post them in the classifieds, and I bet you could get some money for them. If I were in the Detroit area, I'd be there in a hot minute.


----------



## yngdiego




> Quote:
> Originally Posted by *eugovector* /forum/post/14000446
> 
> 
> Woah, don't trash 'em dude. Someone here will take them. Post them in the classifieds, and I bet you could get some money for them. If I were in the Detroit area, I'd be there in a hot minute.



Ya I could use several uncut ones, but I think shipping would be too much to the west coast.


----------



## Peter M

I think the mistake you're making is to concentrate on frequency rather than time.


I've just installed bass absorbers in my two front corners, and whilst my frequency response hasn't changed a great deal, I could immediately hear the benefit of the reduced reverb times (which I haven't measured).


I have absolutely no hesitation in recommending this for others to try.


And if you're worried about the health effects, then re wrap the pieces in thin plastic garbage bags. This has no effect on the frequencies we're trying to absorb.


----------



## Mupi




> Quote:
> Originally Posted by *Peter M* /forum/post/14002133
> 
> 
> I think the mistake you're making is to concentrate on frequency rather than time.
> 
> 
> I've just installed bass absorbers in my two front corners, and whilst my frequency response hasn't changed a great deal, I could immediately hear the benefit of the reduced reverb times (which I haven't measured).
> 
> 
> I have absolutely no hesitation in recommending this for others to try.
> 
> 
> And if you're worried about the health effects, then re wrap the pieces in thin plastic garbage bags. This has no effect on the frequencies we're trying to absorb.



yeah you have a point. The FR has not changed but the boominess is not there as much. Earlier the bass guitar sound was just boomy and the boominess use to linger for a while now the boominess is not there as much and also I noticed that the same base guitar sound seems to be shorter in time i.e as if the guy took his finger off from the guitar.


Is this what you are talking about reverb time etc.


How do I make that waterfall plot. I have REW but I dont know how to make the impulse reading and I also dont know how to interpret the waterfall plot.


So are are saying that putting them in plastic bags does not hurt its effectiveness. Some folks in this thread were debating if felt would be acoustically transparent. Well if plastic bag does not hurt then anything would be fine right?. Now is the plastic bag ok only for low frequencies or for both low and high. I have the uncut panels on the side and front walls as absorbers for high frequencies.


I have put in so much effort into this so I dont want them to go waste.

*If the health risks are not worse than the fibers from the carpet and if I dont have any vents near the panels, can I just leave them uncovere*?


----------



## penngray




> Quote:
> Total 24 2'' panels. 8 of them are still uncut. I might keep 3 to cover the
> 
> fire place as it seems to insulate the fire place from cold draft (I dont use the fire place). Only for those 3 I will add some cheap cover.
> 
> 
> I live in Detroit metro. If anyone is interested in taking them let me know.
> 
> I am not asking for a lot of money. May be $25 to cover the cost to wrap those 4 panels with some cloth/frame.
> 
> They are well cut. oh yeah you can take the slicer too. I had of them.
> 
> One got very dull so I trashed it. Other one is new and I only cut some 5-6 panels using that.



Sorry you feel that they didnt do much but I posted a long time ago (here and in your thread) that sometimes treatments does very little for problem FR plots. Your treatements I suspect did a great job in the reverb times (as Peter posted above). I think you have other setup and room issues that treatments can not solve.


I think they will still work for you and fabric is cheap over at Jo-ann fabric so get some and cover them up. Anything looks better then OC703







You can put anything over them, more reflective fabric will stop the absorbtion of only high frequences, lower frequencies are still absorbed


----------



## r_pogo

Walmart burlap is cheap and for me looks just fine. Coarse weave is good at higher frequencies also. Does not stretch much and requires lots of staples for a smooth appearance. I worry that plastic might buzz up against a fixed surface.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/14003939
> 
> 
> Sorry you feel that they didnt do much but I posted a long time ago (here and in your thread) that sometimes treatments does very little for problem FR plots. Your treatements I suspect did a great job in the reverb times (as Peter posted above). I think you have other setup and room issues that treatments can not solve.
> 
> 
> I think they will still work for you and fabric is cheap over at Jo-ann fabric so get some and cover them up. Anything looks better then OC703
> 
> 
> 
> 
> 
> 
> 
> You can put anything over them, more reflective fabric will stop the absorbtion of only high frequences, lower frequencies are still absorbed



His traps still fell a few feet short of the ceiling. And, depending on the size of his room, perhaps three wall/wall corners are not enough trap. First, I'd fill them to the ceiling. And being the firm believer in SSC bass traps that I am, I would suggest that the OP consider placing some at ceiling/wall "corners." In my 13x21x8 room, the two front wall/wall corners and the front wall/ceiling corner traps made a HUGE improvement. (See sig)


Just my $.02.


----------



## zmisst

looking for low profile, reasonably attractive ceiling diffusion, preferably in black; anyone have any experience with:



GIK D1 Diffusor http://www.gikacoustics.com/gik_d1_diffusor.html 


RPG Hemiffusors http://www.rpginc.com/products/hemiffusor/index.htm 


or


Studio Outfitters Roundffusor http://www.studiooutfitters.com/roundffusor.html 


or other suggestions?


----------



## eugovector

Has there ever been a definitive answer to how far you need to sit away from a diffuser for it to be effective?


----------



## Peter M

Mupi,


Bass boominess is exactly what we mean by reverb time. According to most measurement standards the reverb time, measured in seconds, is the time it takes the sound level to drop 60dB. It's obviously frequency dependent and so the reverb time can be quoted for any particular frequency or as a graph covering all frequencies. An important design goal is to have similar reverb times at all frequencies, and many designers aim for around 0.35 seconds, in a typical sized home theatre. As room size increases the target reverb time also increases.


It's obviously much harder to tame the reverb time in the lower frequencies, due to the absorber size required, but my experience has certainly made me a believer. I went pretty large with my corner absorbers; the side lengths of the triangles are 24" / 24" / 35".


The facing or wrapping to be used depends entirely on the frequency range you're trying to absorb. For bass traps almost anything is OK. For full range absorbers the open weave fabrics are best.


The main problem with the fibres is not long term health problems, but severe itchiness from them getting into your skin. If this happens the best remedy is to rinse in COLD water.


----------



## pepar




> Quote:
> Originally Posted by *Peter M* /forum/post/14010023
> 
> 
> The main problem with the fibres is not long term health problems, but severe itchiness from them getting into your skin. If this happens the best remedy is to rinse in COLD water.



Warm water opens pores allowing the fibers to penetrate deeper making them harder to remove. Cool/cold water does the opposite.


----------



## penngray




> Quote:
> I went pretty large with my corner absorbers; the side lengths of the triangles are 24" / 24" / 35".



Im going 17"/17"/24" in two corners but I might build a 24"/24"/35" in the one other corner.


Is there a huge difference between those sizes?


----------



## penngray

Also on my back wall, Im put up that 4" thick treatment suggested a long time ago but Im back wondering if I should leave an 1" air gap between it and the wall?


What does that improve again? Why 4" thick and a 1" air gap, why not 5" thick instead? No doubt, Im constantly confused.


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/14011519
> 
> 
> Im going 17"/17"/24" in two corners but I might build a 24"/24"/35" in the one other corner.
> 
> 
> Is there a huge difference between those sizes?



Being a DIY and non-commercial solution, testing has been nearly non-existent. The test referenced at the Studiotips Forum is for the 24" face version. Even behind my false wall, I could not fit that size. So I went with the 24" face. Material costs factored in as well. If you search and find commercial product comparisons to the 24" face, please post.


- Jeff


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/14011550
> 
> 
> Also on my back wall, Im put up that 4" thick treatment suggested a long time ago but Im back wondering if I should leave an 1" air gap between it and the wall?
> 
> 
> What does that improve again? Why 4" thick and a 1" air gap, why not 5" thick instead? No doubt, Im constantly confused.



I believe I remember a pro or two recommending that, but I only have 2" OC SelectSound Black panels on the back wall sized *exactly* as needed for first reflection point absorption. If that's what this is for - I apologize for not following your project closer - then the 4" with or without the gap will no doubt be better than my 2". The gap enhances the panel's LF absorption be adding a diaphramatic component to it. Personally, I like my bass absorption in the corners where _all_ of the bass frequencies can be found.


----------



## penngray




> Quote:
> I believe I remember a pro or two recommending that, but I only have 2" OC SelectSound Black panels on the back wall sized *exactly* as needed for first reflection point absorption. If that's what this is for - I apologize for not following your project closer - then the 4" with or without the gap will no doubt be better than my 2". The gap enhances the panel's LF absorption be adding a diaphramatic component to it. Personally, I like my bass absorption in the corners where all of the bass frequencies can be found.



Yeah, I total suck at keeping my build thread going. Been keeping my DIY sub thread up to speed just have so many pics to add to my HT build thread.


The reason for the 4" treatment on the back wall is because I sit 1' from the back wall in my HTRoom so it was recommended that I need some serious treatment behind my seating. Room design and seating is FIXED so no need to discuss why I shouldnt do that







I just want to try and handle the problems I created.


The real question is more of a generic one that I can seem to find in a search.


What is the difference acoustically between 4" acoustical treatment up against drywall vs 3" acoustical treatement, then a 1" air gap, then the drywall?


----------



## pepar




> Quote:
> Originally Posted by *penngray* /forum/post/14011673
> 
> 
> The real question is more of a generic one that I can seem to find in a search.
> 
> 
> What is the difference acoustically between 4" acoustical treatment up against drywall vs 3" acoustical treatement, then a 1" air gap, then the drywall?



The difference is what I posted above. As for quantifying the difference, I haven't a clue on where to find tests. Maybe ask whoever made the recommendation?


----------



## penngray




> Quote:
> The gap enhances the panel's LF absorption be adding a diaphramatic component to it. Personally, I like my bass absorption in the corners where all of the bass frequencies can be found.



Ah...cool. I missed that.


The 4" behind the seating was discussed in this thread a bit ago. One of the experts gave me that recommendation.


----------



## Ethan Winer




> Quote:
> Originally Posted by *eugovector* /forum/post/14009211
> 
> 
> Has there ever been a definitive answer to how far you need to sit away from a diffuser for it to be effective?



The closest "test" I have is a short video that lets you hear the sound when _very_ close to a diffusor. Bottom of this page:

RealTraps Videos 


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14013841
> 
> 
> The closest "test" I have is a short video that lets you hear the sound when _very_ close to a diffusor. Bottom of this page:
> 
> RealTraps Videos
> 
> 
> --Ethan



Very nice. Great idea.


----------



## beatboy77

I have read through this thread and cannot find an answer to my questions.


1. How do you attach the Linacoustic to the drywall?


2. How do you attach the GoM to the Linacoustic?


~Josh


----------



## Dan Woodruff




> Quote:
> Originally Posted by *beatboy77* /forum/post/14014273
> 
> 
> I have read through this thread and cannot find an answer to my questions.
> 
> 
> 1. How do you attach the Linacoustic to the drywall?
> 
> 
> 2. How do you attach the GoM to the Linacoustic?
> 
> 
> ~Josh



1) Short sheetrock screws. Don't screw them all the way in though (1/4 to 3/8 inch is more than sufficient). It only takes a couple, even for the largest pieces.


2) Place 1 inch furring strips at the ceiling, floor and corners. Fasten the GoM to the furring strips.


----------



## r_pogo

Here is a link about fiberglass health issues:

http://www.lungusa.org/site/c.dvLUK9...Fiberglass.htm 


Does not seem to be a major problem but more studies are likely on the way.


----------



## Peter M

I went with the largest corner absorbers I could fit in, without encroaching on the placement of my front speakers. There was no testing or calcs behind my decision at all. Getting material isn't a problem as we use about 300,000 cubic feet of rockwool per annum at work.










When I eventually move home and build a dedicted room my mad plan is to use 3 foot thick rockwool covering about 1/2 of the front wall and 2/3 of the rear wall.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Peter M* /forum/post/14017899
> 
> 
> I went with the largest corner absorbers I could fit in, without encroaching on the placement of my front speakers. There was no testing or calcs behind my decision at all. Getting material isn't a problem as we use about 300,000 cubic feet of rockwool per annum at work.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> When I eventually move home and build a dedicted room my mad plan is to use 3 foot thick rockwool covering about 1/2 of the front wall and 2/3 of the rear wall.



Beware, Peter. Rockwool is generally pretty dense, and has a very high flow resistivity at higher densities. This translates to ineffective absorption for a really thick (like 3 ft) layer.


What happens is that the waves don't penetrate all the way through the thickness, some fraction being reflected. So the whole depth isn't really used. You get better low frequency absorption with less dense material. This can be approximated/predicted through relatively simple mathematical methods.


Regards,

Terry


----------



## Peter M

Terry,


We typically use 40kg/m3 rockwool. I believe at this density it should be OK ?


----------



## Peter M

Terry,


I should have also added that as I move into the real design stage I intend to employ the services of a reputable acoustician, location unimportant. Know anyone you can recommend ?


----------



## SaraJ

Anyone have a sugesstion?

Like this one for example:
http://wroclaw.gumtree.pl/c-Firmy-Us...QAdIdZ54992719


----------



## Terry Montlick




> Quote:
> Originally Posted by *Peter M* /forum/post/14037885
> 
> 
> Terry,
> 
> 
> We typically use 40kg/m3 rockwool. I believe at this density it should be OK ?



Sorry, but substantially less density rockwool for a 3 foot thickness is much more effective at lowest frequencies.







I do not recommend 40 kg/m^3 if you are after best low frequency performance.


I am of course available for detailed hourly consulting via email. And I work pretty cheap, especially considering the current dollar exchange rates.







Just PM me.


Regards,

Terry


----------



## zmisst




> Quote:
> Originally Posted by *zmisst* /forum/post/14008713
> 
> 
> looking for low profile, reasonably attractive ceiling diffusion, preferably in black; anyone have any experience with:
> 
> 
> 
> GIK D1 Diffusor http://www.gikacoustics.com/gik_d1_diffusor.html
> 
> 
> RPG Hemiffusors http://www.rpginc.com/products/hemiffusor/index.htm
> 
> 
> or
> 
> 
> Studio Outfitters Roundffusor http://www.studiooutfitters.com/roundffusor.html
> 
> 
> or other suggestions?



anyone use these or other ceiling diffusors?


Or recommend someone who designs/builds aethetically appealing (i.e., no skylines) ceiling diffusion?


I've heard that ceiling diffusion is often preferable to absorption but it is difficult to find an acceptable way to implement this.


I'm considering just putting in coffers with some trim with absorption in the coffers at the first reflection, and get whatever diffusion the coffers can give for the rest of the ceiling.


Anyone have any pics of Hts with coffered ceilings?


thanks for any ideas.


----------



## Ethan Winer




> Quote:
> Originally Posted by *zmisst* /forum/post/14052414
> 
> 
> I've heard that ceiling diffusion is often preferable to absorption but it is difficult to find an acceptable way to implement this.



I disagree with that advice. I much prefer absorption at reflection points.


--Ethan


----------



## zmisst




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14053542
> 
> 
> I disagree with that advice. I much prefer absorption at reflection points.
> 
> 
> --Ethan



Anyone have any info on comparisons between the two? (That is, specifically comparisons btw types of absorption vs types of diffusion -- not btw absorption vs no treatment.) especially for ceilings, but walls wld be interesting too. and not just reflection points but also general broader treatment? (my original query actually mentioned absorption at first reflection and diffusion elsewhere -- what I thought was a reasonable splitting of the difference).


Or info on whether varies types of diffusion is more or less broadband that various types of absorption? (some claim diffusion is more broadband)


Or have info on why Rives seems to get very good reviews when they seem to always specify diffusion for ceiling treatment? especially low ceilings?


----------



## Ethan Winer




> Quote:
> Originally Posted by *zmisst* /forum/post/14056700
> 
> 
> Anyone have any info on comparisons between the two?



There's no way to measure if diffusion versus absorption is "better" other than subjective impression. I have absorption at all reflection point in my 16 foot wide living room, including the ceiling. When I put diffusors at the side-wall reflection points the degradation in imaging and overall quality compared to absorption was immediately obvious. Yes, this was subjective, but it was so obvious nobody could conclude otherwise.



> Quote:
> Or info on whether varies types of diffusion is more or less broadband that various types of absorption? (some claim diffusion is more broadband)



Absorption will be more broadband, which is another argument in favor of absorption. Now, you could compare a 9-inch deep QRD diffusor versus 1-inch thick sculpted foam, and in that case the diffusor might work over a wider range. It will certainly work to a lower frequency. But a four inch absorber is much more broadband than any practical diffusor. Practical meaning not four feet deep etc.


--Ethan


----------



## Fatawan

In the sketch of my room below, the red area has a very pronounced increase in bass at about 40Hz. You walk over there, and its waaaaay louder than the rest of the room. The subs are in black. Both front and back walls have 2" OC703, front has superchunks in the corners, the back has half sized versions. The face of that bumpout has 2" OC703, and the walls have 1" OC703 at first reflection points. So my question is this---does it matter if there is a big peak over there since I don't sit there, and neither does anyone else? Or, should I try and soak it up with all my leftover OC703? Would it do me any good?


Thanks!


----------



## Terry Montlick

Fatawan,


If it is not broken (in the listening area), don't fix it!


Low frequency room modes will sound really bad at the sides and corners of the room, where their pressures are always maximum. These are also good places to treate them, because if a specific room mode is partly absorbed anywhere, its effect will diminish to some degree everywhere else.


But if it is not an audible problem at the listening area, your effort will be wasted. And depending upon the type of bass absorber placed at that front area, it could adversely effect your sound stage.


Regards,

Terry


----------



## mcneilms

I have a difficult acoustical problem that I need help solving. The rough sketch below shows the general layout of my room. The yellow area is a wet bar that I want to keep and the blue area is the entrance. This makes for difficulty putting bass absorption in the corners. The general dimensions of the main room is about 18' x 17.5' the wetbar and entrance are about 3x3. I plan on having a riser with absorption underneath don't know how else. The screen wall is on the wall along the bar end of the room on the left side of the sketch.


Any help?


----------



## Terry Montlick

Hi mcneilms,


Is this room already built? If so, the best thing is to listen to it from your seats, and measure the frequency and time/frequency response with a program like the free Room EQ Wizard. This can tell you whether you have significant offending room modes, which ones they are, and therefore where treatment can be effective.


If the room is not built, bass absorbers in the two available corners and/soffits running around the room can be an effective deterrent.


Regards,

Terry


----------



## pmeyer




> Quote:
> Originally Posted by *mcneilms* /forum/post/14066609
> 
> 
> I have a difficult acoustical problem that I need help solving. The rough sketch below shows the general layout of my room. The yellow area is a wet bar that I want to keep and the blue area is the entrance. This makes for difficulty putting bass absorption in the corners. The general dimensions of the main room is about 18' x 17.5' the wetbar and entrance are about 3x3. I plan on having a riser with absorption underneath don't know how else. The screen wall is on the wall along the bar end of the room on the left side of the sketch.
> 
> 
> Any help?



If you do measure and decide you need bass traps, you may be able to get creative in where they go. If this room has attic above it, can you punch a hole in the ceiling above the wet bar or entrance and put a bass trap up there? If the bump-out between the wet-bar and the entrance is a closet in another room, can you turn part of that into a bass trap?


If this room has unused basement below it, another weird option would be bass trap built into the floor (think big metal grate). You could get double duty out of it by making the grate a trap-door and dropping guests you dislike through the floor as they are standing at the wet bar...


Hopefully you can get away without bass traps in those corners, but something to think about. Here is a shot of the bass trap over my entrance (2' x 4' by 2' deep):


----------



## CruelInventions




> Quote:
> Originally Posted by *pmeyer* /forum/post/14067166
> 
> 
> .......You could get double duty out of it by making the grate a trap-door and dropping guests you dislike through the floor as they are standing at the wet bar...



lol, a grate for the grating!


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/14067166
> 
> 
> If you do measure and decide you need bass traps, you may be able to get creative in where they go. If this room has attic above it, can you punch a hole in the ceiling above the wet bar or entrance and put a bass trap up there? If the bump-out between the wet-bar and the entrance is a closet in another room, can you turn part of that into a bass trap?
> 
> 
> If this room has unused basement below it, another weird option would be bass trap built into the floor (think big metal grate). You could get double duty out of it by making the grate a trap-door and dropping guests you dislike through the floor as they are standing at the wet bar...
> 
> 
> Hopefully you can get away without bass traps in those corners, but something to think about. Here is a shot of the bass trap over my entrance (2' x 4' by 2' deep):



Not that your entrance ceiling (or similarly located) trap won't do anything at all, but the idea is to put the traps where the bass "is." First, that is corners formed by three surfaces and second is corners formed by two surfaces. Cleverness and ingenuity are good, but effectiveness is king.


Just my $.02.


----------



## Ethan Winer




> Quote:
> Originally Posted by *mcneilms* /forum/post/14066609
> 
> 
> This makes for difficulty putting bass absorption in the corners.



Most rooms have 12 corners. Listen to Terry. Wall-ceiling corners are very effective, and even wall-floor corners are good if you have any available, such as the bottom of the screen wall.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14070313
> 
> 
> Most rooms have 12 corners. Listen to Terry. Wall-ceiling corners are very effective, and even wall-floor corners are good if you have any available, such as the bottom of the screen wall.
> 
> 
> --Ethan



Indeed, it's not like it requires thinking outside the box, but continuing the metaphor, it surely requires thinking about everywhere _in_ the box.


----------



## pmeyer




> Quote:
> Originally Posted by *pepar* /forum/post/14068740
> 
> 
> Not that your entrance ceiling (or similarly located) trap won't do anything at all, but the idea is to put the traps where the bass "is." First, that is corners formed by three surfaces and second is corners formed by two surfaces. Cleverness and ingenuity are good, but effectiveness is king.
> 
> 
> Just my $.02.



Agreed. Ideally the more room modes a bass trap will hit, the better.


A middle of a wall trap (not touching floor/ceiling) can work on the cross room modes (100 or 010, depending on the wall). A middle of ceiling trap can help with 001 modes. A trap suspended off the floor in a corner (not touching the top/bottom tricorners) will get cross-room modes (110).


A full height corner trap is often standard because it gets you some effectiveness on all of the above. It's got a bit on each wall to cover 100 010, it's in the horizontal plane corner, and therefore gets 110, and it's got the top/bottom tricorners covered, getting some coverage on the 111.


(and higher order modes, but I hate writing x00, etc.)


You can't see the rest of my room, by my entrance is actually in the back left corner. It's canted at 45 degrees to the room. mcneilms sketch seems to imply his entrance is in a corner as well. Because of that, traps in the ceiling or floor right up against the corner will actually have some effectiveness on the XXX eigenmodes (left-back-ceiling corner to right-front-floor). Tricorner traps out in the room, or traps on multiple walls in the corner would help even more.


I'll have two standard superchunks in the front, and a near-corner full upright trap in the back right. When working with Bryan, I suggested big side-wall traps to the left/right of the door (there is space there), but he preferred the ceiling trap. I've got a weird enough shaped room the only way I'll be able to tell what is working is to try it out and measure.


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/0
> 
> 
> I've got a weird enough shaped room the only way I'll be able to tell what is working is to try it out and measure.



Yep, it will be interesting to see the test results.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pmeyer* /forum/post/14067166
> 
> 
> If you do measure and decide you need bass traps, you may be able to get creative in where they go. If this room has attic above it, can you punch a hole in the ceiling above the wet bar or entrance and put a bass trap up there?



Great suggestion. These sorts of bass absorbers would occasionally be used in old recording studios that had free space above the ceiling. There may even be a name for them, though I don't remember what it was. You can use a larger space than the opening size, and just hide the opening with acoustically transparent fabric. Pre-calculating the net absorption is a bear, but in the old days, they just built it and fiddled with it until it sounded good.










Regards,

Terry


----------



## byte02553

Hello all,


I have been reading here for a long time but have not located/found information about the optimum spacing of the corner SSC traps from the corner walls. Should they be tight to the walls or if one was to space them off the wall a certain distance....several inches maybe......would this help for the much deeper bass that is hard to tame....like below 30 Hz? If not...how can we address the very low bass? I will be installing my SSC traps in the next week or so. Thanks.


Wayne


----------



## pepar




> Quote:
> Originally Posted by *byte02553* /forum/post/14076543
> 
> 
> Hello all,
> 
> 
> I have been reading here for a long time but have not located/found information about the optimum spacing of the corner SSC traps from the corner walls. Should they be tight to the walls or if one was to space them off the wall a certain distance....several inches maybe......would this help for the much deeper bass that is hard to tame....like below 30 Hz? If not...how can we address the very low bass? I will be installing my SSC traps in the next week or so. Thanks.
> 
> 
> Wayne



Tight in the corner. For lower absorption, more 'glass needs to be used. That means instead of the 24" face - 24" x 48" sheet cut into eight 17" x 17" x 24" triangles - you need to do the 34" face - each 24" x 48" sheet cut into *FOUR* 24" x 24" x 34" triangles.


----------



## byte02553

Thank you for the response pepar. I will have only little 703 2" left after making the larger SSC corner traps for the four main corners front and back. I will, however, have quite a bit of linacoustic 1" left after treating the front wall with 2". To do a front wall....wall-ceiling trap...could I stack layers of 1" linacoustic to a height of maybe 8"...and put it in a frame...and straddle the wall ceiling corner? Would that work for additional bass trapping? Thanks.


Wayne


----------



## pepar




> Quote:
> Originally Posted by *byte02553* /forum/post/14077292
> 
> 
> Thank you for the response pepar. I will have only little 703 2" left after making the larger SSC corner traps for the four main corners front and back. I will, however, have quite a bit of linacoustic 1" left after treating the front wall with 2". To do a front wall....wall-ceiling trap...could I stack layers of 1" linacoustic to a height of maybe 8"...and put it in a frame...and straddle the wall ceiling corner? Would that work for additional bass trapping? Thanks.
> 
> 
> Wayne



Mmmm, I don't think so. Go here and compare the absorption of the two materials. The 703 goes a LOT lower than Linacoustic.


----------



## zmisst




> Quote:
> Originally Posted by *eugovector* /forum/post/11884302
> 
> 
> 5. I still haven't put up my ceiling panels, so I can't tell you from personal experience, but at the 2007 HES, Richard Bird of Rives Audio cited a study that found that the ceiling was the most important spot to treat.



from a few months back. . . anyone know what this "study" was?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/14077483
> 
> 
> Mmmm, I don't think so. Go here and compare the absorption of the two materials. The 703 goes a LOT lower than Linacoustic.



Beware of reading too much accuracy into reverberation room absorption coefficients, particularly at 125 Hz!


Regards,

Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *byte02553* /forum/post/14076543
> 
> 
> Should they be tight to the walls or if one was to space them off the wall a certain distance....several inches maybe......would this help for the much deeper bass that is hard to tame....like below 30 Hz?



Unfortunately, bass this low is very hard to make a measurable dent in by adding just a few more inches of thickness.










Regards,

Terry


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/14077483
> 
> 
> Mmmm, I don't think so. Go here and compare the absorption of the two materials. The 703 goes a LOT lower than Linacoustic.



Make sure you're comparing the same thing. The 703 is 2" while the Linacoustic is he is using is 1". If you take into consideration the same Linacoustic at 2" the coeffecients are very similar to the 703. They are listed on the coeffecients page.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/14078250
> 
> 
> Make sure you're comparing the same thing. The 703 is 2" while the Linacoustic is he is using is 1". If you take into consideration the same Linacoustic at 2" the coeffecients are very similar to the 703. They are listed on the coeffecients page.



Umm, yeah, so are the 1" specs . . . DOH!


703, plain 1" (25mm) on wall 0.11 0.28 0.68 0.90 0.93 0.96 0.70


Linacoustic RC 1" (25mm) 0.08 0.31 0.64 0.84 0.97 1.03 0.70


----------



## Dan Woodruff

Thanks for posting that, Pepar. So many use the 2" 703 I forgot that it also comes in 1".


I have to admit, when I made my traps, (I used the 1" Linacoustic RC because I had lots of extra) I wished I had purchased the 703. At 1" thick it was, at least, twice the work cutting enough wedges to fill the corners all the way to ceiling.


----------



## byte02553

I have one back corner that has only a 12" length one side and unlimited on the other. So a conventional 17x17x24 is out. Are there other tested shapes that would give me depth enough to be effective?


Wayne


----------



## pepar




> Quote:
> Originally Posted by *byte02553* /forum/post/14093894
> 
> 
> I have one back corner that has only a 12" length one side and unlimited on the other. So a conventional 17x17x24 is out. Are there other tested shapes that would give me depth enough to be effective?
> 
> 
> Wayne



I don't recall seeing any tests of other shapes, but I'd probably build it as a 17x17x24 minus the volume of 'glass occupied by whatever limits the space to 12".


----------



## mcneilms

Thanks guys. Knew y'all could help.


----------



## byte02553

Thank you for your input.


----------



## byte02553

Does anyone know the Johns Mansville equivalent for OC 703? I think I can get it locally to do ceiling first reflection 2x4 panels but am not sure what they call it. Thanks.


Wayne


----------



## Dan Woodruff




> Quote:
> Originally Posted by *byte02553* /forum/post/14110456
> 
> 
> Does anyone know the Johns Mansville equivalent for OC 703? I think I can get it locally to do ceiling first reflection 2x4 panels but am not sure what they call it. Thanks.
> 
> 
> Wayne



Linacoustic RC


It generally comes 1" thick in a 47.5" x 100 foot roll (others lengths are available). It also comes in 2" thickness.


----------



## avare




> Quote:
> Originally Posted by *byte02553* /forum/post/14110456
> 
> 
> Does anyone know the Johns Mansville equivalent for OC 703?


 IS 300 . Linacoustic is 1.5lb/ft^3 while OC 703 and JM IS 300 are 3.0lb/ft^3 material.


Andre


----------



## byte02553

Dan,


I have the Linacoustic RC....but I thought they made a rigid dense fiberglass in panels like the OC703 that had acoustic absorption properties that were very similar. I may be mistaken.......


Wayne


----------



## Dan Woodruff

Wayne,


You're right, sorry about that. I see that Andre gave us a link to what you are looking for.


edit - I do know that the Linacoustic has very similar coefficients to the OC 703 though. http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Fatawan




> Quote:
> Originally Posted by *byte02553* /forum/post/14110745
> 
> 
> Dan,
> 
> 
> I have the Linacoustic RC....but I thought they made a rigid dense fiberglass in panels like the OC703 that had acoustic absorption properties that were very similar. I may be mistaken.......
> 
> 
> Wayne



JM 814 is what I used--same as OC703


----------



## byte02553

thanks Fatawan.....I knew that my memory would be jogged....it was JM 814 I was thinking of.


Wayne.


----------



## bpape




> Quote:
> Originally Posted by *byte02553* /forum/post/14093894
> 
> 
> I have one back corner that has only a 12" length one side and unlimited on the other. So a conventional 17x17x24 is out. Are there other tested shapes that would give me depth enough to be effective?
> 
> 
> Wayne



You can build a 12x12" square absorber using the same amount of material as a 17x17x24 triangle. While not as thick right at the wall edges, it's thicker over a larger area and considerably thicker at 45 degrees to the corner. You also have the same amount of surface area exposed. I have people build these like this all the time.


Bryan


----------



## byte02553

I just might try the square version. Thanks.


Wayne


----------



## R Harkness

Hey folks.


I'm struggling with the age old problem of trying to fit the biggest screen I can into the room, while also fitting in things like acoustic treatment etc. I'm wondering if there might be any solution to my dilemma I haven't thought of.


My screen wall is 160" wide. I'm trying to achieve a 124" wide screen, to be used with a side-masking system, using automated sliding panels. (They actually save me some room on the side over using curtains).


I'm attaching 2 google sketchups of the room. You can see my speakers will be in the corners and I'm going to need some corner acoustic treatment to tame the bass frequency lift. The problem is: how to fit the acoustic corner treatment in?


On the right side of the image near the room opening you can see I have very little _side_ wall before it hits the room opening. Due to space a triangular corner trap is out. An acoustician suggested perhaps two panels for the corner: one narrow one to fit between the edge of the screen frame and the side wall, then another one on what is left of the side wall.













The side wall only extends 14" _including trim for the doorway_ and only 10" to the doorway trim (so I can use an acoustic panel on the side wall that is either going to be 10" wide, or 14" wide if I'm willing to cover the doorway trim). You can see how tight for space I am on this side of the wall near the doorway:











The biggest problem I'm dealing with at the moment is the stacking of the side masking panels to the side of the screen. The panel stack will be almost 7" thick. But if I put an acoustic panel on the side wall that is 3" thick - one on each side of the screen - that will restrict the width at which the masking panels can retract to the side. Adding 3" of acoustic panelling on either side wall of the screen essentially reduces the viewable screen area from 124" wide screen to a 118" wide screen.


I could make the side acoustic panel (near the doorway) start AFTER the width of the masking panels - so the masking panels can go all the way to the side wall to preserve image size. But then that would mean a gap between that sidewall panel and the panel on the screen wall, and make for a sidewall acoustic panel only 3" wide, or 7" wide (if I extend it to cover the doorway trim).


Would this work?


Any other ways out of this dilemma. I'm really trying to maintain the image size I want.


Thanks.


----------



## Kal Rubinson

Remove the rest of the sidewall and eliminate the corner.


----------



## Electric_Haggis

I'm in a similar situation.


Try these things, if you haven't already. They'll make a HUGE difference in both deadening the room and reducing bass boost...


1. Put as much padding around AND behind the screen as possible. Put up a layer of egg cartons, foam or whatever you can manage, followed by black carpet like Wonderwall. You'll have a black "feature wall", and it'll make your projected picture stick out more.


2. Experiment with plugging up the bass ports on your front speakers.


3. Get the front three speakers as far out from the wall as you can manage.


4. Toe in the left and right speakers.


5. If you have a subwoofer, experiment with placement, levels and crossover.


Good luck!


----------



## R Harkness




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/14167145
> 
> 
> Remove the rest of the sidewall and eliminate the corner.



Do you mean take out the drywall on the sidewall and inset the acoustic treatment so it doesn't stick out?


----------



## R Harkness




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/14167841
> 
> 
> I'm in a similar situation.
> 
> 
> Try these things, if you haven't already. They'll make a HUGE difference in both deadening the room and reducing bass boost...
> 
> 
> 1. Put as much padding around AND behind the screen as possible. Put up a layer of egg cartons, foam or whatever you can manage, followed by black carpet like Wonderwall. You'll have a black "feature wall", and it'll make your projected picture stick out more.
> 
> 
> 2. Experiment with plugging up the bass ports on your front speakers.
> 
> 
> 3. Get the front three speakers as far out from the wall as you can manage.
> 
> 
> 4. Toe in the left and right speakers.
> 
> 
> 5. If you have a subwoofer, experiment with placement, levels and crossover.
> 
> 
> Good luck!



Thanks. I have planned to do acoustic treatment on the screen wall as well, but I figured I needed the treatment to wrap around the corner somewhat since my L/R speakers will be about 1 1/2 feet out from the room corners.


----------



## nathan_h




> Quote:
> Originally Posted by *R Harkness* /forum/post/14166999
> 
> 
> 
> Would this work?
> 
> 
> Any other ways out of this dilemma. I'm really trying to maintain the image size I want.
> 
> 
> Thanks.



From personal experience I would say figure out a way to not have the speakers so close to the side wall on the left. The space on the right looks pretty ideal. The proximity of the left side wall can create imaging problems and bass problems that would otherwise be less severe.


"If I had it to do over again" I would sacrifice some screen size for more flexibility with speaker placement.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/14169145
> 
> 
> From personal experience I would say figure out a way to not have the speakers so close to the side wall on the left. The space on the right looks pretty ideal. The proximity of the left side wall can create imaging problems and bass problems that would otherwise be less severe.
> 
> 
> "If I had it to do over again" I would sacrifice some screen size for more flexibility with speaker placement.



I was thinking the same thing. To maximize screen size and still have optimum speaker placement, I'd be looking at an acoustically transparent screen on a false wall - or a drop down AT screen - with the speakers behind the screen.


Just my $.02.


- Jeff


----------



## twenty/twenty

Drop your screen size to a 120"D 2.35 to 1 screen. Move the screen up higher on the wall. Place 3 identical center channel or 3 small identical bookshelf/monitor speakers horizontally beneath the screen as LCR.


----------



## Dennis Erskine




> Quote:
> bookshelf/monitor speakers horizontally beneath the screen as LCR



ONLY if the speakers are specifically designed to be used horizontally. Just because the say "LCR", doesn't mean you can install them anyway you want.


----------



## twenty/twenty

Yep, that didn't come out right.


I meant to say 3 center channels as LCR under the screen, mounted horizontally as designed, well away from the sidewalls, or 3 small bookshelf/monitors mounted vertically as designed, but spread out as LCR in a horizontal fashion, under the screen, well away from the sidewalls. Therefore, if you elect to use Bookshelf/monitors, they have to be short vertically speaking.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *R Harkness* /forum/post/14169077
> 
> 
> Do you mean take out the drywall on the sidewall and inset the acoustic treatment so it doesn't stick out?



That's an idea but I meant that, if you remove the rest of that sidewall (with the big opening), you eliminate the corner as an acoustic issue.


----------



## R Harkness

Great feedback folks,


So you think it would actually sound better if I put the L/R speakers _beneath_ the screen so they would get away from the side walls?


I have contemplated that before. I have little angled stands meant for a similar application. The speaker is held about 6" off the ground but angled up toward the listener...which is how my center channel is sitting at the moment. Acoustic treatment could go on the wall behind the speakers.


All the speakers (which I love and intend to use) are Hales Transcendence speakers - the T1 L/R monitors on stands and the (at one time very expensive) Transcendence Cinema Center Channel, which is quite big and provides a very hefty sound, while matching very well, timbrally, with the L/Rs. I actually do have a second pair of T1 monitors so if I wanted to I could have 3 perfectly matched speakers beneath the screen, but I'd like to try it first with the center channel since it sounds gorgeous.


For those who've tried that L/C/R under the screen, how does the sound match the picture vs the L/R higher and to the side of the screen?


(Kal, thanks, but that's a no-can-do in my room.)


Thanks,


----------



## twenty/twenty

I have personally discussed this concept with two different Cedia level whatever certified designers, a Revel rep, and had several positive reponses from AVS members on a couple different posts. All have stated this approach is much better than sticking the LR near the sidewalls. Your particular room looks like an acoustical nightmare from a timbre matching POV for the L/C/R, having the closed wall on the left and the open wall on the right. I would try to reduce the effects of those sidewalls as much as possible by getting the LR away from them and into the room if possible.


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/14174387
> 
> 
> Great feedback folks,
> 
> 
> So you think it would actually sound better if I put the L/R speakers _beneath_ the screen so they would get away from the side walls?



Definitely get the speakers away from the sidewalls, but *I* think it would sound best with the speakers behind the on-screen image.


----------



## Dennis Erskine

What's the difference between being near a side wall and being near the floor? Not much. Only highly directional speakers can work to help resolve that. None-the-less, even if you move the speakers in from the one side wall, you're going to have a timbre issue...and a big one if you don't have your crossovers at 80Hz and the speaker 3.5' (or better) from any boundary. You can treat the boundary to help; but, you cannot make up for a missing wall.


Getting the speakers higher, like behind the screen (or in front if you prefer), treating the boundary, and getting more directional speakers will all go to improve the situation.


As to your speaker choice. Ok choice; but, what criteria are you using to select those speakers? If you did not put them in YOUR room, positioned where you intend to, the speakers you heard are NOT the speakers you will hear. Just beware. What sounded good in one place may not sound good in another.


----------



## R Harkness

Thank you for weighing in Dennis...



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14175233
> 
> 
> What's the difference between being near a side wall and being near the floor? Not much. Only highly directional speakers can work to help resolve that. None-the-less, even if you move the speakers in from the one side wall, you're going to have a timbre issue...and a big one if you don't have your crossovers at 80Hz and the speaker 3.5' (or better) from any boundary. You can treat the boundary to help; but, you cannot make up for a missing wall.



I'm not sure I followed that. Wouldn't the scenario be somewhat evened out by having the 3 speakers beneath the screen, well away from the side walls (since I have a very uneven side-wall situation)? One other issue is that if you look at the sketches I posted you'll see that the speaker on the right is very close to the fireplace which is reflective metal and tile about 2 feet from the right of the tweeter. Not ideal







so I think maybe getting it away from there could help (in putting the L/R beneath the screen...with the wall treated behind them). No?


FWIW I don't intend to use a subwoofer (various reasons).



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14175233
> 
> 
> Getting the speakers higher, like behind the screen (or in front if you prefer), ...



Sorry I'm a bit confused again. When you say "or in front if you prefer" do you mean following the suggestion of others in putting the speakers below the screen?



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14175233
> 
> 
> As to your speaker choice. Ok choice; but, what criteria are you using to select those speakers? If you did not put them in YOUR room, positioned where you intend to, the speakers you heard are NOT the speakers you will hear. Just beware. What sounded good in one place may not sound good in another.



Oh yeah...I'm all too aware of that. This used to be my high-end audio listening room. In order to make it into a Home Theater I've had to flip the location of the sofa and speakers 180 degrees. In doing so I went from having wonderful acoustics, and beautiful smooth response from practically any decent speaker I put in there...to...yuck! Suck-outs, peaks, crappier sound all around, even moving the speakers away from boundaries. I'm not happy.


Still, the Hales speakers are sounding "themselves" enough that I still like them and wish to salvage the enterprise somehow. The center channel were it is, beneath the screen actually sounds terrific (despite some bass bloat as I haven't treated anywhere).


To make all these matters worse, I'm STILL trying to use this as my 2 channel listening room too! My plan was to have the L/R speakers on stands and when I want to listen to 2 channel, pull the stands out into the room closer to the listening sofa for what I would hope would be better acoustics (or at least cutting out more of the room effects).


Thanks.


----------



## twenty/twenty

Rich,


I have been reading your posts now for over 3 years.


Quite frankly, I am very surprised at what you are trying to do with this room.


The Rich I have known from your previous posts would never consider using a front projection set up in this room for a multitude of reasons both on the audio side and the video side.


I I were you, an extremely picky videophile, I would either pick a different room for your HT, give up on the front projector and go with a big LCD or Plasma, or rip out the columns and close that room off with a new sidewall and door.


Wait for the new 70 inch Sony LCD with LED backlighting. Mount it high enough on the wall so that you have room to get the LCR's well off the floor and in from the sidewalls. Anyway you do it with this room, you are going to hate seeing the tops of those speakers lit up from the light coming from the screen.


----------



## Dennis Erskine

Dang nabit. It's too early for this.










Exchanging one boundary condition for another isn't necessarily going to result in improvement (wall vs floor). Although floors tend to have moderate treatments (carpet & pad). What needs some investigation is the off axis response of the speakers. As well, a perfectly symmetrical placement simply means the SBIR from the left speaker is reinforced by the SBIR from the right. Here, however, the L/R differences are to the extreme.


The in front of the screen comment was tongue in cheek. Sorry.


Here's a telling comment, however. For two channel you're putting the speakers on stands and moving yourself closer to the near field. Why should speaker placement change? If the sound is better with the speakers pulled away from the walls and placed higher for two-channel, why would you degrade the sound just because you have your center channel running? In the end (in this case), to get a big picture, audio becomes the sacrificial lamb simply because the space doesn't lend itself well to boundary treatments.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14175233
> 
> 
> What's the difference between being near a side wall and being near the floor?



Well, I can see that the big difference would be that the speaker designers "know" where the floor is and, if they are worth their salt, design for it. They have no idea where the side walls are. Some designers will include a SBE adjustment, but it needs to be engaged by the customer and then it is usually only a coarse correction. The simple solution is, as was recommended, keep speakers away from side walls.


----------



## Dennis Erskine




> Quote:
> Well, I can see that the big difference would be that the speaker designers "know" where the floor is and, if they are worth their salt, design for it.



I wish that were true. In a better world CE speaker manufacturers would give us polar plots like we have in the Pro side. Unfortunately, while only makers of floor standing speakers "know" where the floor is, measurements don't show any effort to minimize floor/ceiling interactions except for those few with directed wave guides (and similar mechanisms like horns (ala JBL for example). This is before we even get to the lobing effects. Typically horizontally aligned (or "center") speakers tend to be more forgiving of floors/ceilings and less forgiving of adjacent walls.


Again, because designers know that listeners tend to be on a very narrow vertical plane, above and below driver off axis response tends to be very poor while left to right off axis response is (in some cases) given some attention. These factors become very critical in room set up and design. With good off axis response, we want more reflection (and diffusion) and less absorption. With bad off axis response, we want absorption.


----------



## R Harkness




> Quote:
> Originally Posted by *twenty/twenty* /forum/post/14177971
> 
> 
> Rich,
> 
> 
> I have been reading your posts now for over 3 years.
> 
> 
> Quite frankly, I am very surprised at what you are trying to do with this room.
> 
> 
> The Rich I have known from your previous posts would never consider using a front projection set up in this room for a multitude of reasons both on the audio side and the video side.
> 
> ......
> 
> 
> Wait for the new 70 inch Sony LCD with LED backlighting. Mount it high enough on the wall so that you have room to get the LCR's well off the floor and in from the sidewalls. Anyway you do it with this room, you are going to hate seeing the tops of those speakers lit up from the light coming from the screen.



If you'd been reading my posts you should know a 70 inch LCD is probably the last display I'd buy

















I've never really cared for LCDs, can't stand the off-axis performance among other things. I'd been planning the room around a 65" plasma but once I borrowed a friend's projector I was hooked on the cinematic experience. Plasmas are too small.


I won't see the tops of the speakers lit up: I've already experimented and will be covering the speakers with black material - they totally disappear when I do this.


Thanks twenty/twenty.


----------



## R Harkness




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14178075
> 
> 
> Dang nabit. It's too early for this.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Exchanging on boundary condition for another isn't necessarily going to result in improvement (wall vs floor). Although floors tend to have moderate treatments (carpet & pad). What needs some investigation is the off axis response of the speakers. As well, a perfectly symmetrical placement simply means the SBIR from the left speaker is reinforced by the SBIR from the right. Here, however, the L/R differences are to the extreme.



Thanks for the info.


What I have to do, I think, is get an AV receiver into the room so I can experiment to see what the speakers sound like in the corners vs aligned below where my screen would go.


The Hales speakers were known for good off-axis performance - one of the design goals. Previous to switching the room design, I'd had the Hales L/R monitors on the small stands that angle them from the floor. They sounded quite good, aside from a bit too much bass, which I hope I can tame somewhat with treatment. Anyway, I guess we can speculate only so long so it's time for me to try this out. I certainly appreciate your input.



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14178075
> 
> 
> 
> Here's a telling comment, however. For two channel you're putting the speakers on stands and moving yourself closer to the near field. Why should speaker placement change? If the sound is better with the speakers pulled away from the walls and placed higher for two-channel, why would you degrade the sound just because you have your center channel running? In the end (in this case), to get a big picture, audio becomes the sacrificial lamb simply because the space doesn't lend itself well to boundary treatments.



Audio is essentially the sacrificial lamb here, in terms of maximising picture over sound.


Unfortunately in this room orientation (and it's the only one that will work with a projection set up), the speakers simply can not be left in an optimal position for 2 channel listening, as they would be too far into the room and especially with respect to the doorway, be in people's way, might be knocked over and just destroy any possible traffic flow in the room. Not only that, optimally setting up for 2 channel in this room would mean a very small projection screen to fit between the L/R speaker positions, at which point it would be "why bother?"


So the best solution I can figure is I could have the speakers on stands put more toward the corners and with treatment get good, if not optimal sound for movies from them. And when I'm going to listen "critically" to 2 channel music, I'd just pull the L/R speakers out to my standard position, more nearfield - not that much of a physical hassle. That's the best I can come up with since this is the only room I have for such things and have to deal with the challenges of trying to satisfy my desire for both Home Theater projection and my two channel listening.


Thanks.


----------



## nytheaternoob




> Quote:
> you are going to hate seeing the tops of those speakers lit up from the light coming from the screen.



i can say that i definitely do hate it in my ht.


i was wondering, if i put velvet on top of my speakers to absorb the light, will that hurt the sound? i'm trying to make these suckers disappear when they movie is on. my room is a bat cave: everything is painted black, black seats, and charcoal gray carpet. but those gosh darn speakers (even tho black) are annoying under the screen. i don't have room to put them behind the screen


----------



## R Harkness

I'm in the same position in wanting the speakers to dissapear, so I've tried black velvet

on the speakers. It certainly made them disappear when on the sides of the screen. And I do remember it seeming to work with my center channel as well.


Even if you have black speakers they are still going to reflect light, hence if you really want to make them disappear it seems covering the reflective surface with some material is the way to go. The other thing I've done to minimize reflection is to angle the speakers upward toward the listening position, such that I can't see the tops of the speaker - the only thing facing me is the black grills so I don't see the speaker with the lights off.


----------



## nytheaternoob

actually, maybe velvet would be bad (high frequencies). i dunno.


btw, do any of you sound gurus know if this is bad for the sound: to black out light from windows, i cut these and thumbtacked them to interior of the windows, but material is not cushy or foamy, it's like plastic.

http://www.lnt.com/product/index.jsp...entPage=family 



53% polyvinyl chloride, 35% polyester, 12% polyurethane



my room: two windows on the side wall (about 1 foot above LCR and begin at 1 foot from the front of the speakers). one 70 inch window behind the screen. one 70 inch window on the back wall.


if i should put acoustical treatments in the windows (for example, the auralex foam i have blocks light), do you reommend any certain thickness/material types?


----------



## nytheaternoob

i will try to take some pics if that's easier


----------



## nytheaternoob

never mind the previous posts. the two side windows are not at the first reflection points. front and back windows i'll figure out at some point. i guess i'll try to create a bass trap that fits.


----------



## snookfisher

O.K. sorry to do this but ive just started the process of finishing the garage and need a little help....here is the basics:


ROOM..A standard two car garage. almost square dimensions.


equiptment... paradigm studio 60s the larger studio center from paradigm and the seismic 12 sub.


can you guys recomend a source for me to refer to regarding acoustical treatments. this thread is HUGE and Im sure its all here but i just don have the time to read it all. Thanks in advance!!


----------



## Ethan Winer




> Quote:
> Originally Posted by *snookfisher* /forum/post/14191372
> 
> 
> can you guys recomend a source for me to refer to regarding acoustical treatments. this thread is HUGE and Im sure its all here but i just don have the time to read it all.



No kidding. Some of the posts in this thread discuss how useless this thread has become because of the size and so much conflicting advice.










Room treatment is a deep subject, so here's the short version which will get you 99 percent of the way there. All rooms need:


* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further. You simply cannot have too much bass trapping. Real bass trapping, that is - thin foam and thin fiberglass don't work to a low enough frequency.


* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.


* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective. Diffusion on the rear wall behind you is also useful in larger rooms.


For the complete story see my Acoustics FAQ. 


There's a lot of additional non-sales technical information on my company's web site - articles, videos, test tones and other downloads, and much more.


--Ethan


----------



## snookfisher

thanks Ethan.. ill check it out now!!!


Randy


----------



## CJO

I was wondering if anyone could help me out with an acoustics question-


When I first designed my theater, I was going to use inwalls (Triad Classic Gold Inwall LCR's) in the front wall and purchased the speakers on that assumption. I later decided, for sound isolation purposes, that it would be better to sheetrock that wall and build a false wall in front of it for the screen and the LCR's.


Would I be better off putting up sheetrock on the false wall since the inwall speakers were designed to mount against a reflective surface, just mount them to the studs and leave the screen wall open, or put the sheet rock most of the way up, but leave the top open so that I can put bass trapping behind the false wall? I would assume the last option, but wanted to check before proceeding.


Here is my build thread with a drawing:
http://www.avsforum.com/avs-vb/showthread.php?t=1043747 


Thanks,

CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/14191874
> 
> 
> I was wondering if anyone could help me out with an acoustics question-
> 
> 
> When I first designed my theater, I was going to use inwalls (Triad Classic Gold Inwall LCR's) in the front wall and purchased the speakers on that assumption. I later decided, for sound isolation purposes, that it would be better to sheetrock that wall and build a false wall in front of it for the screen and the LCR's.
> 
> 
> Would I be better off putting up sheetrock on the false wall since the inwall speakers were designed to mount against a reflective surface, just mount them to the studs and leave the screen wall open, or put the sheet rock most of the way up, but leave the top open so that I can put bass trapping behind the false wall? I would assume the last option, but wanted to check before proceeding.
> 
> 
> Here is my build thread with a drawing:
> http://www.avsforum.com/avs-vb/showthread.php?t=1043747
> 
> 
> Thanks,
> 
> CJ



For bass traps to work behind a false wall, the false wall needs to be acoustically transparent - at least at the lower frequencies. Will your speakers be behind an AT screen?


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/14191997
> 
> 
> For bass traps to work behind a false wall, the false wall needs to be acoustically transparent - at least at the lower frequencies. Will your speakers be behind an AT screen?



The speakers will be behind an AT screen. However, I don't think I described very well what I thought the best option would be. That would be to mount the speakers in a false wall that is sheetrocked up to about 2 feet below the ceiling. I'm covering the wall in fidelio velvet, so the bass should be able to pass right through that opening.


Here's a diagram:










Thanks,

CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/14192432
> 
> 
> The speakers will be behind an AT screen. However, I don't think I described very well what I thought the best option would be. That would be to mount the speakers in a false wall that is sheetrocked up to about 2 feet below the ceiling. I'm covering the wall in fidelio velvet, so the bass should be able to pass right through that opening.
> 
> 
> Thanks,
> 
> CJ



Sorry to seem like I want to spend your money, but with your design change (solid drywalling instead of in-wall spkrs there), have you considered non-inwall speakers? The inwalls' reason for being is no longer. And "regular" speakers don't have the compromises that inwalls have. They might be getting better, but they are still compromised.


A wall closely spaced behind an AT screen would cause comb filtering.


Just my $.02.


- Jeff


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/14192571
> 
> 
> Sorry to seem like I want to spend your money, but with your design change (solid drywalling instead of in-wall spkrs there), have you considered non-inwall speakers? The inwalls' reason for being is no longer. And "regular" speakers don't have the compromises that inwalls have. They might be getting better, but they are still compromised.
> 
> 
> A wall closely spaced behind an AT screen would cause comb filtering.
> 
> 
> Just my $.02.
> 
> 
> - Jeff



Don't worry- it's a good balance. You try to convince me to spend my money and my wife tries to convince me not to! I'm guessing that I'll be using the inwalls for the next year or two.


I thought that the screen being too close to the speakers cause the comb filtering.. I plan to have the screen offset about 6 inches from the false wall. Also, I forgot to mention that I will put 2" of OC 703 or similar on the drywall (but obviously not in front of the speakers).


Thanks,

CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/14192658
> 
> 
> Don't worry- it's a good balance. You try to convince me to spend my money and my wife tries to convince me not to! I'm guessing that I'll be using the inwalls for the next year or two.
> 
> 
> I thought that the screen being too close to the speakers cause the comb filtering.. I plan to have the screen offset about 6 inches from the false wall. Also, I forgot to mention that I will put 2" of OC 703 or similar on the drywall (but obviously not in front of the speakers).
> 
> 
> Thanks,
> 
> CJ



You also have the recommended distance between speaker baffle and screen. I've always thought it to be at least 9" with +12" being better. I guess my point is that you may make the effort to use the inwalls only to find that the performance is unacceptable. And then have to expend even more effort to correct it - with wall mounted speakers instead of inwalls. And 12" plus speaker depth between wall and false/screen wall.


Check the website linked in my sig - the neverending home theater upgrade. I've passed this way already.


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/14193567
> 
> 
> You also have the recommended distance between speaker baffle and screen. I've always thought it to be at least 9" with +12" being better. I guess my point is that you may make the effort to use the inwalls only to find that the performance is unacceptable. And then have to expend even more effort to correct it - with wall mounted speakers instead of inwalls. And 12" plus speaker depth between wall and false/screen wall.
> 
> 
> Check the website linked in my sig - the neverending home theater upgrade. I've passed this way already.



Boy- not what I wanted to hear! Aren't onwall speakers designed with the same near-wall boundary considerations as inwall speakers? At least I have a few months before I'm far enough along to where I really have to make a decision.


Thanks for the information and advice,

CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/14196930
> 
> 
> Boy- not what I wanted to hear! Aren't onwall speakers designed with the same near-wall boundary considerations as inwall speakers? At least I have a few months before I'm far enough along to where I really have to make a decision.
> 
> 
> Thanks for the information and advice,
> 
> CJ



I'm pretty sure that inwall speakers are designed specifically to be flush with a wall. As for "non-inwall" speakers, they are not designed with any boundaries in mind. Some users will put them on stands, some wall-mounted and others perhaps in home entertainment furniture.


But my caution is re the distance between speaker face and screen and your wall and screen for reasons of comb-filtering. If you haven't, check my website.


You have time, so seek the opinions of others before deciding.


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/14197135
> 
> 
> I'm pretty sure that inwall speakers are designed specifically to be flush with a wall.



They are.



> Quote:
> Originally Posted by *pepar* /forum/post/14197135
> 
> 
> As for "non-inwall" speakers, they are not designed with any boundaries in mind. Some users will put them on stands, some wall-mounted and others perhaps in home entertainment furniture.



Sorry- I didn't pay close enough attention. I thought that you were using onwall speakers rather than free standing speakers. Good onwall speakers also take into account the boundary effects of the wall on which they are mounted.



> Quote:
> Originally Posted by *pepar* /forum/post/14197135
> 
> 
> But my caution is re the distance between speaker face and screen and your wall and screen for reasons of comb-filtering. If you haven't, check my website.
> 
> 
> You have time, so seek the opinions of others before deciding.



You are now using an SmX screen, which is what I'm going to be using. According to Ruben and based on measurements that he has taken, you can mount their screen within a couple of inches of the speaker without any noticeable comb filtering. I'm not sure that I buy that, which is why I was extending that to 6 inches...


Thanks again,

CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/14197348
> 
> 
> Sorry- I didn't pay close enough attention. I thought that you were using onwall speakers rather than free standing speakers. Good onwall speakers also take into account the boundary effects of the wall on which they are mounted.



That was my thinking until Mr. Erskine posted this .



> Quote:
> You are now using an SmX screen, which is what I'm going to be using. According to Ruben and based on measurements that he has taken, you can mount their screen within a couple of inches of the speaker without any noticeable comb filtering. *I'm not sure that I buy that*, which is why I was extending that to 6 inches...



Me neither, but Ruben knows his product and I am not able to reconcile it. Anyway, I'll remeasure tonight as I might have misremembered the distance between the screen and the speaker baffle.


- Jeff


----------



## nytheaternoob

ugh this is becoming a pain trying to get tweeters to be ear level without being in the way of the screen. speakers have to be lower than screen's bottom edge obviously.


if speakers are low (say, 16 inches off the floor), should i add another plush rug under them to reduce the reflections?


----------



## pepar




> Quote:
> Originally Posted by *nytheaternoob* /forum/post/14198421
> 
> 
> ugh this is becoming a pain trying to get tweeters to be ear level without being in the way of the screen. speakers have to be lower than screen's bottom edge obviously.



a c o u s t i c a l l y t r a n s p a r e n t s c r e e n.



> Quote:
> if speakers are low (say, 16 inches off the floor), should i add another plush rug under them to reduce the reflections?



The thickest carpet pad you can find would be good.


----------



## Don_Kellogg

I'm sure I already know the answer to this but here goes. Would there be a huge issue of using Knauff? board to patch an area in a theater that has Lin RC 1" everywhere else. I only need a 4'x12' piece of Lin but of course I have to buy a roll of 50' to get it. Knauff comes in 4x10' and several places stock it.


I'm probably going to go with a roll of Lin RC but just wondered if there was a big enough difference between the two to cause issues.


----------



## Terry Montlick

No, Knauf won't work!!


Just kidding.










Knauf 2.25 pcf fiberglass is fully equivalent to JM Linacoustic RC.


Regards,

Terry


----------



## Dennis Erskine

Knauf, Knauf, who's there?


What Terry said (the second time).


----------



## LDD1

On GIK website it says that GIK’s design of the 244 (and The GIK Monster Trap) is to allow it to be used in quantity, to absorb as much bass as possible without over absorbing the high end, which leaves life inside of the room.


What is designed into GIK Panels to prevent over absorbtion at the mid and high ends?


How does this compare to the membrane on the Realtraps panels?


----------



## pepar




> Quote:
> Originally Posted by *LDD1* /forum/post/14258120
> 
> 
> On GIK website it says that GIK's design of the 244 (and The GIK Monster Trap) is to allow it to be used in quantity, to absorb as much bass as possible without over absorbing the high end, which leaves life inside of the room.
> 
> 
> What is designed into GIK Panels to prevent over absorbtion at the mid and high ends?



Not GIK, nor do I play GIK on television, but the highs are absorbed at the surface and total absorption depends entirely upon _surface area_. Absorbing mids requires more depth (thickness), but no additional _surface area_, i.e. no more highs are absorbed. And lows require even more depth in the absorber - the more depth, the more absorption. Again, this is all accomplished with no additional (high frequency absorbing) _surface area_.


Usually, the amount of deep bass traps needed does not contain enough surface area to over deaden the room. It's not that anybody's traps are designed to prevent over absorption, it's just that the amount required to do the job doesn't deaden the room. It is a happy coincidence of physics.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/14259319
> 
> 
> Absorbing mids requires more depth (thickness), but no additional _surface area_, i.e. no more highs are absorbed. And lows require even more depth in the absorber - the more depth, the more absorption. Again, this is all accomplished with no additional (high frequency absorbing) _surface area_.



Have to disagree with you here, pepar. The Sabin is the fundamental unit of sound absorption *at any frequency*. Metric Sabins have the dimensions of square meters, and Imperial Sabins the dimensions of square feet. Surface area is implicitly involved in computing and using sound absorption materials.


At low frequencies (wavelengths comparable or large with respect to the dimensions of the surface), diffraction effects come into play, and there is not a simple linear relationship with area. But surface area still plays a significant role. I have built very low frequency bass traps which were many feet across, and extending floor to ceiling. Yes, these were also very deep (about 3 feet). As you correctly point out, absorption frequency is related to depth of absorber. but this does not allow one to skimp on surface area!


Regards,

Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/14260337
> 
> 
> Have to disagree with you here, pepar.



Thanks, Terry. From LDD1's post, a quote he says is from GIK's site, how would you answer his query:


"_*GIK's design of the 244 (and The GIK Monster Trap) is to allow it to be used in quantity, to absorb as much bass as possible without over absorbing the high end, which leaves life inside of the room.*_


What is designed into GIK Panels to prevent over absorbtion at the mid and high ends?"


----------



## allredp




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/14260337
> 
> 
> I have built very low frequency bass traps which were many feet across, and extending floor to ceiling. Yes, these were also very deep (about 3 feet). As you correctly point out, absorption frequency is related to depth of absorber. but this does not allow one to skimp on surface area!



Terry,


So what effect did this kind of enormous "very low FR" bass trap have on mid/high frequencies?


What frequencies are absorbed exactly with such a huge bass trap?


Thanks for the help!


Phil


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/14260657
> 
> 
> What is designed into GIK Panels to prevent over absorbtion at the mid and high ends?"



I don't know what they use. But one typically uses a thin membrane on the surface, such as paper or foil, which will reflect high and mid (depending on the membrane weight, cavity depth, etc.) frequencies.



> Quote:
> What frequencies are absorbed exactly with such a huge bass trap?



I have designed some to absorb with a peak frequency below 30 Hz. I have also designed wideband absorbers that absorb very efficiently from 50 Hz all the way up to 20,000 Hz.


The important thing is that a bass absorber does not generally have neatly separable components, each with their own independent characteristics -- membrane, porous absorption layer, etc. All of these interact to form a system with certain composite properties.


The interactions are, for the most part, relatively simple. This is physics, guys! You can't say that you have a mass that resonates at 100 Hz, or a spring that resonates at 100 Hz. You may have a mass on top of a spring (on top of the earth), which together resonate at 100 Hz.










Regards,

Terry


----------



## Amon

I am not sure this is the right place to put this question, so please let me know if this question should be in a different forum.

I am currently in the process of looking for a house to rent and one of the good candidates has a room with walls made of wood logs (on the inside). The outside of the house is brick, and I am not sure how much insulation there is between the logs and the bricks. One of the walls is drywall, and I plan of putting a screen/tv there. There is only one level in the house. This is the biggest living area in the house and there is not much outside light, so I'm thinking it may make for a good theater/game room. The log room is carpeted. The ceiling is constructed with wood as well. There is another smaller living area with drywall, but there are hardwood floors and much more light coming in. Which room would sound best, untreated? Which room is easiest to treat - financially and labor-wise ? I plan on putting a 5.1 system in that room. Any help would be greatly appreciated.


----------



## R Harkness
























Just reporting back in for a moment. I had the dilemma of where to put my speakers for the best sound, especially as the very wide screen puts the speakers into the corners. I finally got hold of an AV receiver to get an idea of what kind of sound I'm getting with the speakers configured as above. I tried a couple things:


1. I tried the Hales dedicated Center channel with the Hales monitors on the sides. They are timbrally quite close and the center channel is a killer speaker in of itself. However I was fairly aware of the "center-channel" insofar as voices coming from the speaker. I'm really trying to free the sound up to get "out" of the speakers and "on to" the screen.


As I have _two_ pairs of the Hales L/R monitors, I tried replacing the centre channel with another monitor, hence 3 of the exact same speakers for L/C/R, all arranged vertically (the center monitor below the screen on a stand angled up to the listener). Not surprisingly, this really did result in a greater cohesiveness to the sound, making it more like a continuous soundfield across the image. The monitor isn't _quite_ as direct or clear as the center channel it replaced, but I think the coherency makes up for it and the sound does seem to stick more to the screen (you lucky folks who can do behind-the-screen speakers!).


At this point I'm wondering how much of this coherent quality I might get if I put the center speaker back in and use the Audyssee room eq from this amp. (One of the next things to try).


2. As per some other suggestions (and I was going to try it anyway), I also tried taking the speakers off the stands and aligning them under the screen, to get them away from the side walls. I figured this would actually work better but it actually did not. The sound was more congested when placing the speakers under the screen. I lost that open, expansive spaciousness and the sound did seem to come from "under" the image. The L/R speakers, when on their stands to the side of the screen, actually sounded better and seemed to "lift" the soundfield up more to screen height.


So I think I know where my speakers will be placed. I have to say I was actually surprised given the speaker placement how darned good movies sounded! Pretty smooth and spacious. More serious 2 channel listening with only the L/Rs shows I have acoustic work to do, though. It still sounds somewhat crude.


All this...and I am actually also doing an experiment trying some other speakers which could be amazing or a disaster.










Anyway, that's it for my update. I appreciate very much the input of folks on the thread. I'll no doubt be getting to some more questions as things progress (and my acoustician is doing up a design at the moment that I wouldn't mind passing by the people here as well).


Thanks,


----------



## rbuck

Hello everyone,


First of all, i am extremely green on sound treatments and principles. All that i know is from reading these forums.


I am in the final stages of remodeling my basement room into a home theater. I have read most of this thread but there is so much to process. I am looking for some simple directions on how to treat my room.


Some information:

Since the room was already finished, i was limited with what i could do with regards to placement of speakers.

My room is 14.5 x 25 x 8.5. I am using half the room for the HT, so that is approx 14.5 x 13 x 8.5.

I really only have 1 90 degree corner in the room, that is in the back by the riser. The other "corners are angles, or doorways, or a wet bar.


The front wall is a floor to ceiling wall unit made from Oak, with speaker boxes for LCR. all the cavities are filled with insulation.

The sub is in a small half height cabinet on the right side of the room

In the back of the room i have a 12" riser, and there are 2 in ceiling speakers. The riser is also filled with insulation

The back wall and 1 side wall have windows


All the equipment is brand new. I haven't even powered it up yet, so i don't know what anything sounds like. i was waiting until the "construction" phase was complete before i unpacked the equipment due to dust, etc.


All the speakers are B&W, and the Sub is Velodyne DD-10

The receiver is the Sony STRDA5300ES Receiver.


Both the receiver and the sub have microphones and software for eq'ing the room.


In all the speaker boxes, i treated the inside with 1" OC705. I have more left over and could build panels with the extra.


So would like to treat the room, but not really sure where to start.


Should i start with the utilities with the receiver and sub? Not sure what type of information/output that would provide me to understand what to do next though.


I have read a little bit on REW, would that be better?


- Should i treat first reflections with the 705? Something else?

- In my 1 90 corner, i imagine i should put a base trap there? Make it out of the 705 or something else?


I am not an audiophile by any means, i would just like to provide the best HT environment within the limits that i have. I cant afford a professional to come test/treat my room. besides i like the DIY aspect of it anyway.


I am open to suggestions. Please ask me more more information as needed.


Thanks for any help.


----------



## Ethan Winer




> Quote:
> Originally Posted by *rbuck* /forum/post/14342613
> 
> 
> I am looking for some simple directions on how to treat my room.



Yeah, there's too much information in this thread, and much of it is conflicting and confusing. Start here:

How to set up a room 
Bass traps article 


--Ethan


----------



## rbuck

Thanks Ethan.

I read over the information. Good stuff.


My challenge is that since i have no flexibility as to where to place the speakers, i need to maximize what i can with what i have.


What would be a good way to do that?

Should i get REW and start running tests?


Will the EQ software included with my equipment be sufficient? - i suspect not.


Also, should i build some panels out of the OC705? or would it be better to use it for a base trap and get something else for panels?


Thanks for the help.


----------



## pepar




> Quote:
> Originally Posted by *rbuck* /forum/post/14343447
> 
> 
> Thanks Ethan.
> 
> I read over the information. Good stuff.
> 
> 
> My challenge is that since i have no flexibility as to where to place the speakers, i need to maximize what i can with what i have.
> 
> 
> What would be a good way to do that?
> 
> Should i get REW and start running tests?
> 
> 
> Will the EQ software included with my equipment be sufficient? - i suspect not.
> 
> 
> Also, should i build some panels out of the OC705? or would it be better to use it for a base trap and get something else for panels?
> 
> 
> Thanks for the help.



There are quite a few knowledgeable acousticians on this thread. I recommend that you get a few opinions before taking any particular course of action.


----------



## rbuck

Thanks pepar,

Nice build BTW.


Feel free to lob in your recommendations as well


----------



## pepar




> Quote:
> Originally Posted by *rbuck* /forum/post/14344857
> 
> 
> Thanks pepar,
> 
> Nice build BTW.
> 
> 
> Feel free to lob in your recommendations as well



I am not an acoustician and could only tell you that what I've done in my room has made a huge improvement and has resulted in a room/system that is quite impressive.


BTW, the "conflicting" information on this thread is mostly with regard to which of it is "too much."


----------



## Ethan Winer




> Quote:
> Originally Posted by *rbuck* /forum/post/14343447
> 
> 
> Should i get REW and start running tests?



You could measure your room, but it won't tell you much. Mostly it will show you how bad things really are.







Regardless of what you measure the solution is more or less the same: As many corner bass traps as is practical, and absorption at the reflection points on the side walls and ceiling.



> Quote:
> Will the EQ software included with my equipment be sufficient?



EQ is never a substitute for bass traps and other room treatment.


--Ethan


----------



## rbuck

Thanks Ethan.


That will get me going.

A few more questions:


I have a box of OC705, so that is the basis for some of these questions.


- is OC705 good for first reflections? Or better for a base trap?

- for side walls, how high/long should i add OC70x? is a 2x4 panel sufficient dimension? My speakers are 39" tall, and are close to the side wall.

- does a corner trap need to be 100% filled with material (ie corner wedges) or can it be a series of progressively smaller vertical panels behind each other.

- for a corner that is greater than 90, would a trap be needed?

- my sub is in a cabinet, my intent was to fill the cabinet space around the sub with OC70x, hoping it would alleviate any potential issues. Worthwhile?


Thanks Ethan!


----------



## rbuck

also, for those interested. Here is a rough markup of my room. Maybe it will help make recommendations.


There is/will be furniture in the room.

4 recliners on the platform. Table and chairs on the left side of the room.

sofa in front of the platform.


I am concerned with the windows on the right side of the room, as well as the back wall. Any suggestions there will be appreciated.


Thanks,

Roby


----------



## pepar




> Quote:
> Originally Posted by *rbuck* /forum/post/14349371
> 
> 
> also, for those interested. Here is a rough markup of my room. Maybe it will help make recommendations.
> 
> 
> There is/will be furniture in the room.
> 
> 4 recliners on the platform. Table and chairs on the left side of the room.
> 
> sofa in front of the platform.
> 
> 
> I am concerned with the windows on the right side of the room, as well as the back wall. Any suggestions there will be appreciated.
> 
> 
> Thanks,
> 
> Roby



I'd be concerned about the right wall, too. But my concern would be about the speaker so close to it. As laid out, the left and right speakers will sound dramatically different. Any way to rotate your theater 90° clockwise putting the screen over the window and having L&R speakers well off - and equidistant from - the walls?


----------



## Ethan Winer




> Quote:
> Originally Posted by *rbuck* /forum/post/14349084
> 
> 
> - is OC705 good for first reflections? Or better for a base trap?



Sure, 705 is good for both.



> Quote:
> for side walls, how high/long should i add OC70x? is a 2x4 panel sufficient dimension?



It depends on how deep your room is and other factors. For a home theater I'd think you want at least two panels on each side wall. And more on the ceiling.



> Quote:
> - does a corner trap need to be 100% filled with material (ie corner wedges) or can it be a series of progressively smaller vertical panels behind each other.



Panels four inches thick are fine, and filled is better. But only a little better. Not proportionally better for the amount of extra material needed.



> Quote:
> for a corner that is greater than 90, would a trap be needed?



Yes.



> Quote:
> my sub is in a cabinet, my intent was to fill the cabinet space around the sub with OC70x, hoping it would alleviate any potential issues. Worthwhile?



I don't know what you mean. But generally, you want bass traps in as many corners as you can, including those where the walls meet the ceiling (and floor if possible).



> Quote:
> Here is a rough markup of my room.



Is the screen at the top and your seating at the bottom? If so, you'll do a _lot_ better rotating the setup 90 degrees clockwise so the screen is on the right side.


--Ethan


----------



## rbuck




> Quote:
> Originally Posted by *pepar* /forum/post/14350320
> 
> 
> Any way to rotate your theater 90° clockwise putting the screen over the window and having L&R speakers well off - and equidistant from - the walls?



Hi pepar,

Unfortunately no. everything is fixed. So i am trying to improve the areas that I can, realizing there will be some challenges that i may not be able to overcome.


Can you suggest anything to help to alleviate the fact the speakers are not equidistant from the walls?


----------



## rbuck




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14350769
> 
> 
> - I don't know what you mean. But generally, you want bass traps in as many corners as you can, including those where the walls meet the ceiling (and floor if possible).
> 
> 
> - Is the screen at the top and your seating at the bottom? If so, you'll do a _lot_ better rotating the setup 90 degrees clockwise so the screen is on the right side.
> 
> 
> --Ethan



Thanks Ethan,

Let me see if i can offer a better description. My sub is in a cabinet in the right side of the room. the cabinet opening is larger than the sub itself, so i was going to fill the remainder of the open space with OC705. Is this reasonable? Waste of time?


Regarding the layout of the room, its fixed (completed). i cant move anything. Can you offer any suggestions to improve the situation, given that I cant move anything?


Thanks for the help!


----------



## pepar




> Quote:
> Originally Posted by *rbuck* /forum/post/14357314
> 
> 
> Hi pepar,
> 
> Unfortunately no. everything is fixed. So i am trying to improve the areas that I can, realizing there will be some challenges that i may not be able to overcome.
> 
> 
> Can you suggest anything to help to alleviate the fact the speakers are not equidistant from the walls?



You can reduce the side boundary effect (SBE) with heavy duty absorption and make it better, but it still may sound different. An AVR/pre-pro with Audyssey would help.


----------



## rbuck




> Quote:
> Originally Posted by *pepar* /forum/post/14357365
> 
> 
> You can reduce the side boundary effect (SBE) with heavy duty absorption and make it better, but it still may sound different. An AVR/pre-pro with Audyssey would help.



Hi pepar,

Can you help me understand what is heavy duty?

I have treated the "inside" of the speaker column with OC705. I can put absorption panel(s) on the side wall as well.


What would you recommend?


Also, my AVR (Sony) has eq software, but i dont believe its Audyssey.


Thanks for the help!


----------



## Ethan Winer




> Quote:
> Originally Posted by *rbuck* /forum/post/14357363
> 
> 
> i was going to fill the remainder of the open space with OC705.



Okay, sure, that's fine and probably a good idea..


--Ethan


----------



## mazekl

I just bought 114 sf of 2" 6 lb rockboard and 96 sf of 4" 8 lb rockboard for $184.27 including tax and shipping.










I bought it in Birmingham Alabama from Shook and Fletcher , but they have several other locations in the Southeast. They are also a dealer for Certainteed, J-M, Knauf and Owens Corning, so I bet they can get your Certainteed Commercial Board 300, J-M I/S 300, Knauf Insulation Board and O-C 703 fiberglass board too. I'd guess they'd probably also have great deals on those fiberglass board products, but I really didn't check.


A week ago I talked to the folks at the Shook and Fletcher central phone number - they were just as disinterested in our small projects as all the other commercial suppliers seem to be.







Today I just walked into one of their offices and met Randy Durbin. He is happy as heck to handle the kinds of little sales we need - so I told him I'd post his name and number out on the forums we frequent. Contact him directly at (205) 595-8441 or [email protected] .


DISCLAIMER: I'm not affiliated with Shook and Fletcher, nor related to, nor otherwise acquainted with Randy - I'm just a happy customer.


BTW, I spent a whole week exchanging emails and phone calls with manufacturers and dealers all over the country. Originally I was very ignorant about their own perspective regarding the purpose for their products, but by the time I finally got to Randy I knew exactly what manufacturers and model names I was actually interested in. More importantly, I knew exactly what applications the dealer thought those models were used in (even though we would all be using them in soundrooms and theaters).


You'll find that the above list is a pretty good list of products you should be asking for in your first conversations. The dealers think that all the rockboard and the fiberglass board products referred to above are used for insulating commercial buildings.


As documented on Bobs Gold , there are a bunch of other products, like duct board for example, that work just fine for us. But my experience is, if you bring up these alternative products AND the commercial building insulation products in the same conversation, you'll just confuse the dealer and make him more resistive to helping you. I'd suggest if you need to explore these alternative products, do so in DIFFERENT conversations with the dealer.


Enjoy!


Kirk


----------



## Randy Ta

My dedicted HT is 16x27 with 9ft ceilings. I'm about ready to paint and wanted to install some basic accoustical treatments before I start. In the attached picture, a false wall will be constructed about 2 ft in front of the front wall and my speakers will all go behind an 11ft wide AT screen. From what I have read, I should put 2" OC703 panels on the front wall from floor to ceiling and maybe 4 ft down the side walls. Not sure what else I should do at this time. When the room is completed and furnished I will have a pro come in, take some measurements, and tell me what else needs to be done. Just trying to save a little money and mess at this time. Any recommendations would be appreciated.


Thanks Randy


----------



## Ethan Winer




> Quote:
> Originally Posted by *Randy Ta* /forum/post/14392043
> 
> 
> From what I have read, I should put 2" OC703 panels on the front wall from floor to ceiling and maybe 4 ft down the side walls. Not sure what else I should do at this time.



If you have two feet of empty space in front, I'd put foot-thick fiberglass on the front wall. Two feet thick is even better. You also need absorption on the rear wall, the side-wall and ceiling reflections points, and very thick fiberglass in every corner including where the walls and ceiling meet. If you do that, you won't need to hire a pro later.










Much more here:

Acoustics FAQ 


--Ethan


----------



## Randy Ta




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14399654
> 
> 
> If you have two feet of empty space in front, I'd put foot-thick fiberglass on the front wall. Two feet thick is even better. You also need absorption on the rear wall, the side-wall and ceiling reflections points, and very thick fiberglass in every corner including where the walls and ceiling meet. If you do that, you won't need to hire a pro later.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Much more here:
> 
> Acoustics FAQ
> 
> 
> --Ethan



Thanks for the response Ethan. I may not really have that much empty space behind my false wall as that is where my speakers will go. Might only be a foot because I don't know at this time what kind of speakers I'll get. Or are you saying to put fiberglass everywhere except where the speakers go? If so, what kind of fiberglass?


Thanks Randy


----------



## stjoh

I'm in the same situation. I've got a false wall approximately 1 foot from the actual front wall. I was going to cover it with 1" Linacoustic or similar. Would it be better to fill the whole area (1 foot thickness) with regular fiberglass? If I do Linacoustic is it better to attach it to the actual wall or to the front or back of the false wall (creating an air gap between the fiberglass and the actual wall)?


Also, is there any value at all in treating the area behind the screen (non acoustically transparent)?


----------



## dbbarron

In my situation (and this was arrived at by testing):


4" of rockwool covered by another 1" linacoustic across front wall behind screen.

4" panels of rockwool on back wall (2'x7'x4"x2 panels toward the corners)


1" linacoustic up to 44" on sidewalls- several panels with about 1' between each

1" linacoutic 3x5 panel on ceiling at first reflection point.


----------



## Ethan Winer

Guys, if you have a cavity a foot thick or more, fluffy R38 fiberglass is very good. And it costs less than rigid fiberglass and is easier to find.


--Ethan


----------



## dbbarron

The front and side wall treatment of the alcove (I have an alcove 9' wide and 3.5' deep within which the screen is inset) made the largest single audible and measureable difference in the room. Recall I used 4" of mineral wool (Roxul) covered by 1" linacoustic (easier than covering with black fabric).


----------



## golgi15

I am nearing the completion of my d-i-y home theater and have a quick question concerning bass traps that hopefully all of you out there can help me with.

I currently have clothed covered, wood framed panels that straddle the two front corners of my home theater and go from floor to ceiling. They have an 1 1/2" of Linacoustic backing the cloth, not much help acoustically, but every little bit helps. I was originally going to build superchunk bass traps with OC 703 but I am running out money/time/patience for the bass trap portion of this build.

I can get my hands on as much Linacoustic as I need for the bass traps. I was thinking that maybe I could create a triangular box out of cardboard and then fill it with Linacoustic in odd shapes and pack as much in as I can while still being able to put a top on the triangular box. Would this setup work in a bass trap application?


----------



## CJO




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14408810
> 
> 
> Guys, if you have a cavity a foot thick or more, fluffy R38 fiberglass is very good. And it costs less than rigid fiberglass and is easier to find.
> 
> 
> --Ethan



That's good news. I have a little over a foot behind my screen wall as well as an 18" deep by 23" wide soffit running around the room. The bottom of the soffit will be GOM. It sounds like filling these with fiberglass insulation should do a good job at bass trapping?


CJ


----------



## Glenn Riehl

I'm asking a question here myself, but one suggestion for CJ: Use recycled denim instead of fiberglass. It performs similarly, and you avoid using fiberglass which has tiny particles which tend to get airborne and get into your lungs and is an irritant at best. It can be sealed up, but during construction you should take precautions. Recycled denim is 100% safe and a pleasure to install in this regard.

OK, my question: I am looking to find ideas on a source of pre-made bass traps--the box type with a front membrane that is tuned to a specific frequency. Something competitively priced but still works well. Something modular, like 2' x 2', for ease of installation in a variety of room sizes. Would be a special order. If anyone knows of reliable suppliers or manufacturers of these, please let me know.

Also, if anyone knows an better way to absorb low-end bass in a tight space (i.e., can only fit something on the wall a few inches thick, not much more), please let me know. E.g., I heard of building the tiers under the seats as bass traps, but don't know how well they perform.


----------



## Dennis Erskine

Using the seating platform as a bass trap can work well; however, I would suggest you engage either Terry or myself to get this right. Best results can be obtained when the seating platform extends the full width of the room and runs to the back wall.


----------



## CJO

Thanks Glenn for the recommendation for the recycled denim. A lot of people here have used it with excellent results but I had forgotten about it. Recycled denim makes a lot more sense than fiberglass for these areas as I may want to access them in the future, without bothering with the itchiness and hazards of fiberglass.


CJ


----------



## Ethan Winer




> Quote:
> Originally Posted by *golgi15* /forum/post/14408969
> 
> 
> I was thinking that maybe I could create a triangular box out of cardboard and then fill it with Linacoustic in odd shapes and pack as much in as I can



Yes, that's a good idea.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *CJO* /forum/post/14409305
> 
> 
> It sounds like filling these with fiberglass insulation should do a good job at bass trapping?



Yes.


----------



## Glenn Riehl

Thanks Dennis. Is there any tests done on these sort of things (bass trap tiers) that gives the figures on how much per sq ft of tier it absorbs at what frequency? I just don't know if it will be enough or not, and whether I'll still need other bass trapping of the low bass frequencies.


----------



## Randy Ta

I have been looking for OC 703 to make some traps and just ordered some from Readyacoustics.com on sale for $69 a case, $10 off. Best price I have found so far.


----------



## pepar




> Quote:
> Originally Posted by *Randy Ta* /forum/post/14424258
> 
> 
> I have been looking for OC 703 to make some traps and just ordered some from Readyacoustics.com on sale for $69 a case, $10 off. Best price I have found so far.



What is in a "case?" And how much was shipping?


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/14426152
> 
> 
> What is in a "case?" And how much was shipping?



I took a look at the website and a case is 6 sheets, each 48"x24"x2" (i.e., 48 SF). I'm not sure about shipping.


CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/14427820
> 
> 
> I took a look at the website and a case is 6 sheets, each 48"x24"x2" (i.e., 48 SF). I'm not sure about shipping.
> 
> 
> CJ



That's half of the "bale" that comes from Corning. What I bought had 12 sheets and was 24" x 24" x 48". The price seems reasonable and that quantity is great for making flat panel absorbers. For 17" x 17" x 24" SSC bass traps it would make 8 lineal feet. For the bigger version, 24" x 24" x 34", it would make only 4 lineal feet.


Shipping costs are probably "not insignificant" as a former Sec of Defense liked to say, for the quantity needed for the amount of SSC traps most rooms require.


Just my $.02.


- Jeff


----------



## warlord260

i finished my panel traps last night

oc 703 4" thick covered in muslin stradeling 4 corners

i was very impressed with the difference in sound, bass quality

have not treated first reflection points yet, but so far huge difference

i need to spend some more listening time and also rerun audussy

thanks to all for a very informative thread,

mike


----------



## Randy Ta




> Quote:
> Originally Posted by *pepar* /forum/post/14426152
> 
> 
> What is in a "case?" And how much was shipping?



Shipping was about $20 for a case of 6 sheets. I have contacted everyone that I know of that might sell this stuff and they don't even return the call or e-mail. I should have the 703 in a week.


Randy


----------



## pepar




> Quote:
> Originally Posted by *Randy Ta* /forum/post/14430675
> 
> 
> Shipping was about $20 for a case of 6 sheets. I have contacted everyone that I know of that might sell this stuff and they don't even return the call or e-mail. I should have the 703 in a week.
> 
> 
> Randy



Congratulations!


----------



## warlord260

i have a question i hope someone could answer for me.

my first reflection point for my mains are leather couch one side, leather loveseat other.

what should i do about this?


----------



## Terry Montlick

Did this thread loss about a week of posts after the first of this month??


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/14439215
> 
> 
> Did this thread loss about a week of posts after the first of this month??



All the threads did.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/14439393
> 
> 
> All the threads did.



Well, that's a relief!


Egbert Sousé: Was I in here last night and did I spend a twenty dollar bill?

Bartender: Yeah.

Egbert Sousé: Oh boy, what a load that is off my mind! I thought I'd lost it.

_From "The Bank Dick," W.C. Fields, 1940_


----------



## warlord260

i have another question

i have a window 2 ft. behind the screen. i would like to cover it up, then put 703 panels.

my question is, will the space between window, and board used to cover it up resonate, or cause me any sound issues?

after covered it will be basiclly a hollow box.

what would any of you do?

thanks for your help,

mike


----------



## warlord260




> Quote:
> Originally Posted by *warlord260* /forum/post/14439172
> 
> 
> i have a question i hope someone could answer for me.
> 
> my first reflection point for my mains are leather couch one side, leather loveseat other.
> 
> what should i do about this?



anyone?


----------



## Ethan Winer




> Quote:
> Originally Posted by *warlord260* /forum/post/14442847
> 
> 
> will the space between window, and board used to cover it up resonate, or cause me any sound issues?



Yes, it could. If you pack some fluffy fiberglass inside that will avoid any such problems.


--Ethan


----------



## Cramer_a

I'm looking for a low-cost option for acoustic panels. My theater has a polished concrete floor, so I've got plenty of echo










Will these do the trick?

http://www.acoustimac.com/index.php?...mart&Itemid=19 


Remember, I'm not looking to spend a lot here. I already spent too much on the rest of the basement remodel project.


Thanks for your help.


----------



## eugovector




> Quote:
> Originally Posted by *Cramer_a* /forum/post/14465346
> 
> 
> I'm looking for a low-cost option for acoustic panels. My theater has a polished concrete floor, so I've got plenty of echo
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Will these do the trick?
> 
> http://www.acoustimac.com/index.php?...mart&Itemid=19
> 
> 
> Remember, I'm not looking to spend a lot here. I already spent too much on the rest of the basement remodel project.
> 
> 
> Thanks for your help.



Make your own for about half the price out of 703.


----------



## warlord260

cramer_a:

panels are very easy to make just wrap 703 in speaker cloth, and glue with 3m 77.

i did mine like this then stuffed them in stained frames that i made. they look very nice.

u can get everything local.

i am in kent if you want pm me and maybe i can help


----------



## snookfisher

Ive just finished painting my 16' x 20, room and the carpet is due in in a few days so I need to get on with the acoustic panels. I will be making these with OC 703 and 705 pannels 4" off the wall... Here is my plan:



- Screen wall - 8 pcs of 1" thick 2'x4' OC 703 covered with polly batting and

burlap for complete coverage of screen wall. mounted flush


- side walls - two 4' x4' pannels of OC 703 2" thick on each wall (first reflection points) mounted 4" off the wall


- back wall - one 4' x4' pannel of 2" 703 centered 4"of the wall


- corners - "triangle" traps made with 4" thick OC 705 floor to cieling.....BUT i can only do the two front corners and the LEFT rear corner (there is a door right smack in the RIGHT rear corner.


- ceiling - two 2' x4' 1" 703 pannels just in front of seating positions



A couple questions.....



Any thoughts on this plan....Im all ears


Is three corners going to be a problem ( off balance ect) would I be better off just doing the fronts??


would doubling the thickness of the side and rear wall pannels make any improvements? Is it really worth the extra $


ANY help or suggestions would be MUCHO apreciated!!


----------



## warlord260

snookfisher:

are your corner traps ssc style?

if so save your money and just use the 703,it is said the 703 better performance for these anyway


----------



## snookfisher

Warlord...


Im not sure what ssc style is...


----------



## pmeyer

"studiotips" superchunk. Stacked triangles of fiberglass floor to ceiling.

http://forum.studiotips.com/viewtopic.php?t=535 


They are very common around here for front corners, especially for folks with false screen walls that can hide them.


----------



## snookfisher

No ...Iwas going to basicly make a panel and wedge it in the corner to make a space behind the panel in the corner. I guess it would be a triangle but not "filled"...just 4" thick 705 on the "face" .


----------



## pepar




> Quote:
> Originally Posted by *pmeyer* /forum/post/14470017
> 
> 
> "studiotips" superchunk. Stacked triangles of fiberglass floor to ceiling.
> 
> http://forum.studiotips.com/viewtopic.php?t=535
> 
> 
> They are very common around here for front corners, especially for folks with false screen walls that can hide them.



Check the link in my sig.


----------



## snookfisher

HMMMMMMM...looks like i may reconsider my corner plan...thanks!!


----------



## snookfisher

OH yea...


Any thoughts on doing the left rear corne or would it be better to keep it "balanced" and just do the fronts?


----------



## pepar




> Quote:
> Originally Posted by *snookfisher* /forum/post/14470768
> 
> 
> OH yea...
> 
> 
> Any thoughts on doing the left rear corne or would it be better to keep it "balanced" and just do the fronts?



A corner is a corner. Use all you got.


----------



## pepar

I read on another forum thread that while the mixing engineer for movies sits within the critical distance (nearfield) when mixing, the critical distance extending to one's primary listening position means that the room is over-deadened. The member went on to mention a spec for the correct decay. Now, I've heard the 300ms midband decay spec somewhere, but I thought having one's seats in nearfield is even better. Nirvana even. Can someone please comment on this before I start ripping out treatments!


----------



## avare




> Quote:
> Originally Posted by *pepar* /forum/post/14478646
> 
> 
> I read on another forum thread that while the mixing engineer for movies sits within the critical distance (nearfield) when mixing, the critical distance extending to one's primary listening position means that the room is over-deadened. The member went on to mention a spec for the correct decay. Now, I've heard the 300ms midband decay spec somewhere, but I thought having one's seats in nearfield is even better. Nirvana even. Can someone please comment on this before I start ripping out treatments!



Links would be helpful to know what you read and are referring to. The nominal for small, as in home theaters, is 250 ms for a 3,500 ft^3 room. The smaller the room, the lower. Using an 18x12x8 room as an example, the critical distance is 13.1' if treated per the EBU spec. How large is your room and what is your current treatment. Better yet, what is reverb time also?


Andre


----------



## allredp

Hey, just getting ready to do my room and have a 10' wide area just behind my seating on the back wall that I will be covering with GOM.


What kind of DIY diffusion can I put behind the GOM? I have only got about 1" of depth to play with.


FYI, the rest of the room (upper 1/2 of the wall) will be Linacoustic covered with GOM & I'm planning on running 2" of linacoustic (or 3" of JM 3lb. spinglass) behind my AT screen...


Really appreciate the help!


----------



## cuzed2

I know these questions have already been answered somewhere in this thread already - but this thread is huge, I will apoligize in advance and ask again anyway:


1) I am closing in on my trimwork and theater details. It is time to order GOM fabric samples and select colors to cover my screen wall, bass traps and speaker grills. Would prefer to do business with someone who is active on these forums . Reccomendations?


2) Also; I will be going with two fabric colors; a red/burgundy, and a black for the screen wall and front corner traps. As for the black fabric - which GOM product is everyone using.


Thanks !


----------



## pepar

Not really much "support" required for buying bolts of fabric. I purchase mine from Silent Source .


----------



## Carmen Roebuck

I'll go even further and say you should never cover any large surface area with material that absorbs the mids and highs. It makes the room too dead sounding, and does nothing to solve the inevitable low frequency problems.

You want none of the back reflections to overlay the surround field or the bring the reverberent field forward (your reverberent field and surround field is created by the multi-channel processor or mix, not so much the room as is mandatory for 2-channel).


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/13811035
> 
> 
> My absorbers are 2" Owens Corning SelectSound Black.



Hey pepar (and anyone else who would be kind enough to help!),


Two questions:


1. Is Linacoustic fairly equivalent to the OC SSB you used? If not, is there something "better" at the 1" depth that I could/should use on my *back wall* instead of Linacoustic?


2. Seems like you have begun to feel like you over-dampened your room. I'm planning on 1" Linacoustic all around the upper half of my room (GOM covered) and using a MinWool (6lb RT 80) behind my AT screen. Is that more or less than what you've done (excluding your corner studiotips traps)?


Thanks for the insight!


Phil


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14507206
> 
> 
> Hey pepar (and anyone else who would be kind enough to help!),
> 
> 
> Two questions:
> 
> 
> 1. Is Linacoustic fairly equivalent to the OC SSB you used? If not, is there something "better" at the 1" depth that I could/should use on my *back wall* instead of Linacoustic?
> 
> 
> 2. Seems like you have begun to feel like you over-dampened your room. I'm planning on 1" Linacoustic all around the upper half of my room (GOM covered) and using a MinWool (6lb RT 80) behind my AT screen. Is that more or less than what you've done (excluding your corner studiotips traps)?
> 
> 
> Thanks for the insight!
> 
> 
> Phil



Linacoustic RC comes in rolls making it easier to cover expanses of walls easier than sheets. My room has wall carpeting from floor to ear level of seated persons. It was recommended to me that the wall _above_ ear level be untreated. Any surrounds other than monopoles need reflective walls to create envelopment. Since upgrading to the OP 885 and Audyssey my room/system sounds fabulous. While I have removed the rug w/heavy padding in the theater front, I probably will not make any other changes.


----------



## allredp

Thanks for that reply--though I'm concerned about the upper/lower treatment question.


I'm sure I read earlier on this thread that the it is the ratio of wall treatment to wall area that is the key stat for general absorption, not the upper/lower placement. I'm not talking about 1st reflection points, just general surface treatment.


As per the surrounds, I have in-ceiling units just above and to the side of my seating positions. They have a ribbon and a dome tweeter. So I'm curious how they'll do with this setup!


Anyone able to comment on the question of upper vs. lower absorption wall-placement?


Big thanks,

Phil


----------



## sebberry

Ok, seeing how there are thirty-six hundred posts in this thread I am not going to read through them all..










I have a quick question. If I want to stop sounds from crossing through a wall between two bedrooms (roommate likes late night Star Trek marathons) would it be more effective to double drywall/green glue the side of the wall in the room that is producing the sound or on the side of the wall in the room that I want to stop the sound from entering? (my room).


Thanks!


----------



## Dennis Erskine

Better to have the treatment in the room producing the sound.


----------



## pepar




> Quote:
> Originally Posted by *sebberry* /forum/post/14515751
> 
> 
> Ok, seeing how there are thirty-six hundred posts in this thread I am not going to read through them all..
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have a quick question. If I want to stop sounds from crossing through a wall between two bedrooms (roommate likes late night Star Trek marathons) would it be more effective to double drywall/green glue the side of the wall in the room that is producing the sound or on the side of the wall in the room that I want to stop the sound from entering? (my room).
> 
> 
> Thanks!



There are also some wall construction measures that can be taken to reduce transmission.


----------



## sebberry

Thanks guys, that's what I was wanting to hear.. he has so many electronics and computers and stuff on shelves on his wall that I am sure he doesn't want to move anything so I can soundproof.. Seeing that it is better to DD/GG his side of the wall, it might be inscentive to simply turn down the volume










It's a condo, and while I own it, I would rather not tear down the wall to build an isolation chamber


----------



## allredp

Another quick question (I hope!):


As per the pic, I have a 36" wide (floor to fir-down) opening that will now be behind my AT screen on my front wall.


Should I just rock it closed and then apply my 6" of absorption evenly across the entire area (sans Center speaker) behind the AT screen? Or, can/should I go deeper with the absorption in that 36" wide area, since there is more room behind it?


If the absorption isn't "even" would that introduce comb-filtering?


BTW, other than the bottom shelving and my Center speaker, I won't be using the shelves/opening at all. I do want to have some access to the closet behind, but there's a crawl-way to it from another room.


Big thanks on the help!


I'm really excited about getting this done--finally.


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/14507589
> 
> 
> Linacoustic RC comes in rolls making it easier to cover expanses of walls easier than sheets. My room has wall carpeting from floor to ear level of seated persons. It was recommended to me that the wall _above_ ear level be untreated. Any surrounds other than monopoles need reflective walls to create envelopment. Since upgrading to the OP 885 and Audyssey my room/system sounds fabulous. While I have removed the rug w/heavy padding in the theater front, I probably will not make any other changes.



Great info Pepar!


Even though I have mono-poles, I'll probably go for just a "band" of Linacoustic all around the room at ear height and a few inches above.


Would there be a problem if I filled the rest of the height on the upper panels with some quilting batting? I heard that doesn't absorb much of anything. It would have the aesthetic ability to keep my GOM uniformly tight across the whole panel.


Here's some pics of the construction of the wall panels so far.


This thread rocks--I really appreciate everyone's help!


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14518920
> 
> 
> Great info Pepar!
> 
> 
> Even though I have mono-poles, I'll probably go for just a "band" of Linacoustic all around the room at ear height and a few inches above.
> 
> 
> Would there be a problem if I filled the rest of the height on the upper panels with some quilting batting? I heard that doesn't absorb much of anything. It would have the aesthetic ability to keep my GOM uniformly tight across the whole panel.
> 
> 
> Here's some pics of the construction of the wall panels so far.
> 
> 
> This thread rocks--I really appreciate everyone's help!



Quilted batting not absorbing much? Well, it'll absorb the highs.


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/14519330
> 
> 
> Quilted batting not absorbing much? Well, it'll absorb the highs.



Yikes--I didn't realize that!










So, what should you do if only part of your panel is being filled with Linacoustic?


Would you use a faced foam board, or would that also do some absorbing?!


The trick I have is getting my fairly large spans of GOM to look uniformly "tight" or "pillowed" inside my upper panels if I only fill a part of them with absorption.


BTW, pepar, I appreciate your point about preserving the ambient field above for proper surround.


Any ideas?


----------



## allredp




> Quote:
> Originally Posted by *allredp* /forum/post/14518753
> 
> 
> Another quick question (I hope!):
> 
> 
> As per the pic, I have a 36" wide (floor to fir-down) opening that will now be behind my AT screen on my front wall.
> 
> 
> Should I just rock it closed and then apply my 6" of absorption evenly across the entire area (sans Center speaker) behind the AT screen? Or, can/should I go deeper with the absorption in that 36" wide area, since there is more room behind it?
> 
> 
> If the absorption isn't "even" would that introduce comb-filtering?
> 
> 
> BTW, other than the bottom shelving and my Center speaker, I won't be using the shelves/opening at all. I do want to have some access to the closet behind, but there's a crawl-way to it from another room.
> 
> 
> Big thanks on the help!



Bump?


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14521742
> 
> 
> Yikes--I didn't realize that!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> So, what should you do if only part of your panel is being filled with Linacoustic?
> 
> 
> Would you use a faced foam board, or would that also do some absorbing?!
> 
> 
> The trick I have is getting my fairly large spans of GOM to look uniformly "tight" or "pillowed" inside my upper panels if I only fill a part of them with absorption.
> 
> 
> BTW, pepar, I appreciate your point about preserving the ambient field above for proper surround.
> 
> 
> Any ideas?



Which of your pics shows the panels you are referring to?


----------



## allredp

Sorry about the dead links--these should work now...


The following pics are of the upper panels (without any treatment yet, nor GOM), and the Front Wall.


I'm also wondering about whether to sheetrock over that 36" wide opening on my Front Wall (where the TV/equipment/shelves are) in order to get uniform absorption behind my screen. Or, should I take advantage of the depth to create a deeper absorption layer in that 36" area? But, would that introduce some comb filtering?


I'm upgrading to a projector and an AT fixed screen that will be part of a large proscenium I'm building. You can see the width of my screen (roughly) by the blue tape in the pic...


Thanks for the help!


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14521957
> 
> 
> Sorry about that.
> 
> 
> It is this one--my front wall. I'm upgrading to a projector and an AT fixed screen that will be part of a large proscenium I'm building.
> 
> 
> Thanks for the help!



Right, but do you have a picture/drawing of the panels you are constructing completely covered with GOM? BTW, no pic at this link, but I went back to your prior post to the image with the same name.


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/14522175
> 
> 
> Right, but do you have a picture/drawing of the panels you are constructing completely covered with GOM? BTW, no pic at this link, but I went back to your prior post to the image with the same name.



I've fixed my original post above--the links should work now.


Thanks for the help!


----------



## stepyourgameup

Regarding the latest quick and dirty method by Jon Risch's, he said that any thickness will do when you just stack 3 rolls of insulation in the corners and tape some fabric to them. Does he mean any thickness of OC705 or any thickness of fiberglass period? I assume that there is no thickness variation in OC705 so he must be saying that ANY type of insulation would work. Am I wrong?


----------



## CJO

I haven't seen the article, but from everything I've read, any unfaced insulation should work.


CJ


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14521742
> 
> 
> Yikes--I didn't realize that!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> So, what should you do if only part of your panel is being filled with Linacoustic?
> 
> 
> Would you use a faced foam board, or would that also do some absorbing?!
> 
> 
> The trick I have is getting my fairly large spans of GOM to look uniformly "tight" or "pillowed" inside my upper panels if I only fill a part of them with absorption.
> 
> 
> BTW, pepar, I appreciate your point about preserving the ambient field above for proper surround.
> 
> 
> Any ideas?



Can you build your panels with an uncovered and hard surface on top?


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/14525594
> 
> 
> Can you build your panels with an uncovered and hard surface on top?



I sure could--though that would mean I have no room treatment other than my front wall 6" absorption behind my AT screen. And the 4" of treatment in the 2 rear-wall columns (18" wide by 6.5' high).


My side-walls are pretty wide though--8' & 10' away from my Mains--is it possible that I won't have FRP problems at that distance?


Also, what should I do with my front wall opening? Should I close it off with sheetrock and then apply the 6" of Roxul (RHT80-6lb 3" thick x 2) or yellow spin-glass (JM 1000-3lb 3" thick x 2)?


Or leave it open and use the extra depth for more absorption?


Big thanks on the help!


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14526512
> 
> 
> I sure could--though that would mean I have no room treatment other than my front wall 6" absorption behind my AT screen. And the 4" of treatment in the 2 rear-wall columns (18" wide by 6.5' high).



I was only asking if you could leave the tops of the panels reflective while still using absorption on the lower half (up to ear level?).



> Quote:
> My side-walls are pretty wide though--8' & 10' away from my Mains--is it possible that I won't have FRP problems at that distance?



There will be reflections. You would need to look at your speakers' off-axis response/output to get an idea of how loud it would be. Sound travels about one foot per millisecond. Subtract the direct path time from the reflected path time and you would know how much of a delay there is.



> Quote:
> Also, what should I do with my front wall opening? Should I close it off with sheetrock and then apply the 6" of Roxul (RHT80-6lb 3" thick x 2) or yellow spin-glass (JM 1000-3lb 3" thick x 2)?
> 
> 
> Or leave it open and use the extra depth for more absorption?



I've seen others suggest stuffing it with fiberglass for a down and dirty trap. If I had a hole like that, that's what I would do.


----------



## stepyourgameup




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14408810
> 
> 
> Guys, if you have a cavity a foot thick or more, fluffy R38 fiberglass is very good. And it costs less than rigid fiberglass and is easier to find.
> 
> 
> --Ethan



Cool, so if I build a cylinder bass trap for my corners, I can just use R38 as long as the diameter of the cylinder is over a foot?


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/14526749
> 
> 
> I was only asking if you could leave the tops of the panels reflective while still using absorption on the lower half (up to ear level?).



I get it--yes, I certainly could put some hard reflective board, etc. up there above whatever height of my Linacoustic at 1" depth and cover it all with GOM. Would that work?




> Quote:
> Originally Posted by *pepar* /forum/post/14526749
> 
> 
> There will be reflections. You would need to look at your speakers' off-axis response/output to get an idea of how loud it would be. Sound travels about one foot per millisecond. Subtract the direct path time from the reflected path time and you would know how much of a delay there is.



Cool. I have an equilateral triangle between my LP and my Mains (11' between each speaker and LP). My Center is also going to be between 11-11.5' - so, using the RP - DP I come up with 14ms for my L-side L speaker, and 18.5ms for my L-side Center & I have 10.5ms for my R-side R speaker, and 15.5ms for my R-side Center. I used the mirror-method. How do those look?



> Quote:
> Originally Posted by *pepar* /forum/post/14526749
> 
> 
> I've seen others suggest stuffing it with fiberglass for a down and dirty trap. If I had a hole like that, that's what I would do.



Wow, that could be a very large bass trap! Do I not need to worry about comb-filtering across the front with that 36" opening being much deeper/more absorption than the other 2.5' on either side that will only have 6" deep?


If I did stuff the back closet, would I do the 6" across the whole wall behind the AT screen (opening and all) and then take the further "fluffy" absorption behind that, or would I begin the "fluffy" stuff flush with the stiff board-type absorption?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14527663
> 
> 
> I get it--yes, I certainly could put some hard reflective board, etc. up there above whatever height of my Linacoustic at 1" depth and cover it all with GOM. Would that work?



Covering it all with GOM is an aesthetic thing? Even though GOM is billed as acoustically transparent, nothing is 100% acoustically transparent. And the sound will be going through it two times. I have seen commercial panel systems that are 100% covered though.



> Quote:
> Cool. I have an equilateral triangle between my LP and my Mains (11' between each speaker and LP). My Center is also going to be between 11-11.5' - so, using the RP - DP I come up with 14ms for my L-side L speaker, and 18.5ms for my L-side Center & I have 10.5ms for my R-side R speaker, and 15.5ms for my R-side Center. I used the mirror-method. How do those look?



That will depend on the level of the delayed sound. the conventional wisdom that I have always bought into is treat all of the first reflections, install bass traps and then listen and measure.



> Quote:
> Wow, that could be a very large bass trap! Do I not need to worry about comb-filtering across the front with that 36" opening being much deeper/more absorption than the other 2.5' on either side that will only have 6" deep?
> 
> 
> If I did stuff the back closet, would I do the 6" across the whole wall behind the AT screen (opening and all) and then take the further "fluffy" absorption behind that, or would I begin the "fluffy" stuff flush with the stiff board-type absorption?



IIRC, you got that 6" recommendation from one of the acousticians here on the thread. That is three times the thickness that I have been told. My understanding is that 2' will do and that the extra 4" spread over the entire wall will not reach low enough to to provide bass trapping, which is best done in corners where all of the nodes "end."


----------



## allredp

Pepar, I appreciate the help.


So, I'm clear, how would I treat only a part of any of those upper panels without using GOM or something similar to cover/make flush the rest of the untreated panel? Just for clarity, the bottom panels are all bead-board and not available for treatment as per WAF.


Man this stuff is complicated, eh?! So, just 2" on the front wall behind the screen would do fine?


How effective will the "down and dirty" closet trap (which is mid-wall behind my screen) be? I can make that about 36" deep and down about 25" from the floor. That may be impossible to say exactly, I know, but is it worth doing?


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14528217
> 
> 
> Pepar, I appreciate the help.
> 
> 
> So, I'm clear, how would I treat only a part of any of those upper panels without using GOM or something similar to cover/make flush the rest of the untreated panel? Just for clarity, the bottom panels are all bead-board and not available for treatment as per WAF.



Dunno, make sure she stands on her head then when in the room?


If you shouldn't place absorption on the top half and you are not allowed to place absorption on the bottom half, I don't know where it can go.











> Quote:
> Man this stuff is complicated, eh?! So, just 2" on the front wall behind the screen would do fine?



It works just fine in my theater.



> Quote:
> How effective will the "down and dirty" closet trap (which is mid-wall behind my screen) be? I can make that about 36" deep and down about 25" from the floor. That may be impossible to say exactly, I know, but is it worth doing?



Three feet of 'glass can't hurt and won't absorb any additional highs and mids over the 2". Plus, it won't be seen and subject to the WAF.


----------



## allredp

I better not quit my day job and become a technical manual writer! Sorry to be confusing--I'm not trying to be.


The bottom panels are decorative, so I'm out of luck there; however, the upper panels are wide-open for full, none, or some treatment.


So, I've been wondering about the viability of creating at least some FPR absorption in those upper panels with smaller-than-the-panel sized pieces of Linacoustic. If I only treated the FPR up to a 52" or so and left the rest of the upper panel untreated, but filled with a hard, non-absorbant board, then I figured I could cover the whole panel with its mixed Linacoustic and reflective with GOM and get something out of it. What do you think?


I could also perhaps fill the entire upper panels on the front wall (the ones outside the screen area) as well, unless that would hurt the surround field. Would I do something similar on the back wall upper panels also?


Great points about the bass trap, etc.


Thanks a lot.


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/14528665
> 
> 
> I better not quit my day job and become a technical manual writer! Sorry to be confusing--I'm not trying to be.
> 
> 
> The bottom panels are decorative, so I'm out of luck there; however, the upper panels are wide-open for full, none, or some treatment.
> 
> 
> So, I've been wondering about the viability of creating at least some FPR absorption in those upper panels with smaller-than-the-panel sized pieces of Linacoustic. If I only treated the FPR up to a 52" or so and left the rest of the upper panel untreated, but filled with a hard, non-absorbant board, then I figured I could cover the whole panel with its mixed Linacoustic and reflective with GOM and get something out of it. What do you think?
> 
> 
> I could also perhaps fill the entire upper panels on the front wall (the ones outside the screen area) as well, unless that would hurt the surround field. Would I do something similar on the back wall upper panels also?
> 
> 
> Great points about the bass trap, etc.
> 
> 
> Thanks a lot.



Your design criteria have put you well beyond my skills. I strongly suggest that you engage a professional who can model your room, work with your decor goals and recommend the correct acoustical treatments for your room. I am afraid that if I "help" you any further, I will screw it up.


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/14529797
> 
> 
> Your design criteria have put you well beyond my skills. I strongly suggest that you engage a professional who can model your room, work with your decor goals and recommend the correct acoustical treatments for your room. I am afraid that if I "help" you any further, I will screw it up.



I appreciate your insight--sorry my room/decor criteria are so complicated.


That's a smart suggestion about a professional. I just happen to be in a lightly-populated part of Idaho, so retaining an acustician locally is impossible!


Still, I'm enjoying the pursuit at any rate and hope to have a great looking and and great sounding room soon.


----------



## SteveMo

I have an acoustical product that is not tested by third party. The product is made by Empire West Inc. and they are known for the Ceilume ceiling tiles. I have the Metro style Ceilume tiles installed and above these are a steel reinforcement ceiling to support the concrete garage above which is a little over a foot higher. The tiles are attached using ceiling link that is ran along the joist using furring strips. The item I have a question about is the back panels which are designed to be added above the existing tiles to add more absorption. They sit like "meat tray" on top of the existing tiles between the runners. These add a significant weight to my tiles for which I may need to reinforce by adding support screws, caulk, or any sollution that would work.


In the past while measuring the effect of adding these panels I made note of absorption in the 40Hz area and bellow that. I am now experimenting with adding two layers of each back panel to observe the effect and they seem to add absorption to the area for which I am targeting. Pictured bellow is the effect of adding two layers to three tiles on the left side center of the front of the room (just above where my four subwoofers are located), and then adding another pair of three back panels to more tiles located directly next to the others so that they are centered in the room.











None











Three pairs of two at the left center front of the room.











Six pairs of two at the front center of the room.


My question is do I continue to add these or is there a more better approach that I could be taking to treat the area above my tiles? I already have enough of these to at least complete half the room.


----------



## SteveMo

I took the pair of back panels and put them on 30 tiles in the front of my room. I added a half layer of R19 between the back panel and tiles then duct tape them together so that it would not show when installed. I also duct taped the tile to the top of each horizontal runner as I went. Here is the result. My subwoofers measure 80dB but for testing purposes I choose to measure 75dB.


----------



## cuzed2

SteveMo,


Thanks for sharing this info - it is helpful as I have just received some of the ceiling-lume Stratford samples, and am still trying to decide if I want to go this route. Love the "look", but am concerned about the acoustic properties, they are so thin and light...


Your ceiling structure seems to make for an even bigger challenge - Seems this is why you are adding the "sandwich insulation absorption" layers to the top-side of the tiles?


I will also be using the Celing Max grid system for mounting. However; I will be mounting directly to the bottom of 2x10 wood joists, that have been packed nearly full with fibergalss insulation. I'm hoping > I will have enough absorptin directly above my tiles that I can skip the ceiling lume backer panels - your experienced opinion?


Thanks,

Craig


----------



## SteveMo

Yes the pressure of off the air off the steel above makes it espicially a challenge. I found that the back panels only made things worse. They make them heavy and difficult to install, then there is the matter that they themselves begin to trap noise but the noise they trap is then reflected back because there is no damping whatsoever. For the higher frequencies the tiles themselves are plenty for absorbing the highs and I have always had no complaints there.


I had tried with the ceiling link, the tiles, and with a layer of R14 laying above the joist. This I found to do more harm than good my particular situation. I would recommend playing a sine wave on a cd or program such as REW and sweep around until you can get them to start shaking. If they are lightly installed they should move very fast, gentle, and make no audible noise. If they are bouncing or causing the grid to slip up then somethings wrong and you may want to try a different type of absorption. The area the insulation above will help treat is your floot ceiling axial node which is when the sound is reflected from both the floor and ceiling. If these waves meet at the level you are sitting at the same instance you have cancellation. This is what we want to avoid. As you can see from the measurements above I have one at around 60Hz that I have been watching for a very long time with other treatments as well.


----------



## cuzed2

SteveMo,


Thanks for the quick response. Seems you have begun characterizing these tiles very well.


What I amtaking away from this is the following:


- The celinglume backer panels are probably not beneficial for our applications, (or at least not worth the added effort/costs)?


- As for noise with them vibrating or moving around in the Ceiling Link system - should not be a problem?


- I get the impression that when compared to conventional commercial/acoustical suspended tiles - that they are NOT detrimental? Perhaps it comes down to just the big question >> the degree of absorption one is expecting?


----------



## SteveMo




> Quote:
> Originally Posted by *cuzed2* /forum/post/14542828
> 
> 
> - The celinglume backer panels are probably not beneficial for our applications, (or at least not worth the added effort/costs)?



I don't see them as worth the cost. The effective difference is quite obvious but these exhibit strange characteristics in absoprtion effeciency when dealing with room boundries and they do not effectively treat an effective area with benificial absorption. They add an interesting reverberation effect. I think this is probobly targeted towards people with taller ceilings.



> Quote:
> - As for noise with them vibrating or moving around in the Ceiling Link system - should not be a problem?



That depends. As I was suggesting with the playing of a sine wave, notice if they are laying directly in a peak or not. If they are, I'm afraid there may be some problems. One very easy way I could find peaks in my room was to simply observe where a tile would rattle. If you have some absorption in your corners your probobly alright. The largest concern here is that a support holding the tile is not firmly in place. I have to resize a few by my door that were cut to short with my extra ceiling link now. I can play Transformers through the whole movie (105dB peaks etc) with no rattles right up until the last explosion shot out of bumblebees cannon. Then the short ceiling link rattles. I will fix that for now but probobly I will be putting some more absorption, perhaps the same in the rear of my room once I get new surround speakers.


I measured the effective rattling limits of these tiles before treatments using one subwoofer in my build thread somewhere. As I recall it had been the entire room was buzzing around 80dB at 63Hz-65Hz and some around other frequencies. In other words other treatments are really going to decrease your chances of having any issues with a rattle here or there. You would have to be listening pretty loud to get that happening I would think. I have seen some suggesting to use weather stripping. Also having an object such as a speaker or other resonant cavity within near proximity will increase the likelyhood there will be an issue. When adding a back panel this becomes the most plausable cause of a rattle. If you run into real serious problems you may try placing the subwoofer in the back of the room which I found to help.[/quote]



> Quote:
> - I get the impression that when compared to conventional commercial/acoustical suspended tiles - that they are NOT detrimental? Perhaps it comes down to just the big question >> the degree of absorption one is expecting?



No much has to do with the installation. How well they are installed will make all the difference. These are really good if you don't like tiny holes because you feel like your at school and want to though pencils at them. Yes, certainly the effective absorption is somewhat a mystery. There is actually an official spokesperson for Ceilume here that showed up right after I changed my title to read Ceilume Expert. You can search/read that thread if you want the official take on the absorption. My room is somewhat very similar to a testing facilty. Concrete square room with a steel ceiling. Placed tiles up there and measured with a HT in it.


----------



## elee532

Can someone clarify reccomended treatment for my front wall...


I thought I had a room treatment plan until I stumbled upon this thread. I read the first dozen pages and I'm more confused than ever.  I'm pretty much a complete amatuer at this and I would appreciate any help that folks can offer...


I'm using my room for 50% surround music, 25% two-chanel music, and 25% home theater.


I'm pretty sure that I understand that I need some treatments on the side walls to deal with first reflections. I'm figuring some 2" panels from either GIK or ATS and using the "mirror test" to determing where the treatments should go.


I'm also thinking something like GIK Tri-Traps to treat the corners, but I'm not sure I could afford any more than two of them right now (although I intend to add more in the future)


I'm not clear on reccomended front wall treatment though. Can anyone offer me some advice here? Am I treating for bass or broadband frequency on the front wall? How do I know where to place treatments on the front wall?


Anything else I am missings? Other treatments that should be in the plans for the future?

Some photos of my room here. 


Note that the first photo shows the end of the room that I will be using as the front. I'll have a 50" plasma mounted on the front wall. Also, you can't tell, but the left wall has a ledge about 4' from the floot with a window above is about 3' tall and 4.5' wide.


Thanks for any help!


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14556401
> 
> 
> Can someone clarify reccomended treatment for my front wall...
> 
> 
> I thought I had a room treatment plan until I stumbled upon this thread. I read the first dozen pages and I'm more confused than ever.  I'm pretty much a complete amatuer at this and I would appreciate any help that folks can offer...
> 
> 
> I'm using my room for 50% surround music, 25% two-chanel music, and 25% home theater.
> 
> 
> I'm pretty sure that I understand that I need some treatments on the side walls to deal with first reflections. I'm figuring some 2" panels from either GIK or ATS and using the "mirror test" to determing where the treatments should go.
> 
> 
> I'm also thinking something like GIK Tri-Traps to treat the corners, but I'm not sure I could afford any more than two of them right now (although I intend to add more in the future)
> 
> 
> I'm not clear on reccomended front wall treatment though. Can anyone offer me some advice here? Am I treating for bass or broadband frequency on the front wall? How do I know where to place treatments on the front wall?
> 
> 
> Anything else I am missings? Other treatments that should be in the plans for the future?
> 
> Some photos of my room here.
> 
> 
> Note that the first photo shows the end of the room that I will be using as the front. I'll have a 50" plasma mounted on the front wall. Also, you can't tell, but the left wall has a ledge about 4' from the floot with a window above is about 3' tall and 4.5' wide.
> 
> 
> Thanks for any help!



Minimum is to treat the first reflection points and corners for bass. Think in all three dimensions - all room surfaces have first reflection points. The biggest difference in my room was from the rear wall absorber. Check the site linked in my thread. Start at the first page.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14557167
> 
> 
> Minimum is to treat the first reflection points and corners for bass. Think in all three dimensions - all room surfaces have first reflection points.



Are first reflection points on the side wall next to the front speakers?


So, given limited starting budget, would it make the most sense to put some 2" panels on the side wall and some bass traps in the corner and treat front and rear walls later?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14558516
> 
> 
> Are first reflection points on theside wall next to the front speakers?
> 
> 
> So, given limited starting budget, would it make the most sense to put some 2" panels on the side wall and some bass traps in the corner and treat front and rear walls later.



Do you have a diagram of the space with all of the important items drawn in?


----------



## eugovector




> Quote:
> Originally Posted by *elee532* /forum/post/14558516
> 
> 
> Are first reflection points on the side wall next to the front speakers?



Side walls, back wall, front wall, ceiling, and floor. Search this thread for "mirror trick" for more info.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14558805
> 
> 
> Do you have a diagram of the space with all of the important items drawn in?



Link #1 and #7...

http://www.avsforum.com/avs-vb/showt...hlight=elee532


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14560309
> 
> 
> Link #1 and #7...
> 
> http://www.avsforum.com/avs-vb/showt...hlight=elee532



Speakers . . screen/display . . seats?


----------



## union1411

lords of the acoustics, what say ye about my lair? does it need thine traps?


----------



## stepyourgameup

I just built a 6" riser out of 2x6s and a 4'x8' piece of plywood. The bottom is hollow. Should I pack it with some R30 insulation to keep it from affecting the bass? It is sitting on carpet with pad on a concrete floor.


----------



## Ethan Winer




> Quote:
> Originally Posted by *union1411* /forum/post/14563334
> 
> 
> lords of the acoustics, what say ye about my lair? does it need thine traps?



All rooms need and benefit from bass traps.


--Ethan


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14562007
> 
> 
> Speakers . . screen/display . . seats?



Is the image below any more helpful? Unfortunatley, it's not drawn to scale or anything. Also, I have't exactly figured out where my surround speakers or sub are going to be placed.


So, I think I understand that I need some absorption panels on the side walls. What's not clear to me is whether I need some on the front wall as well.


I'm also thinking some bass traps in some corners. How do I determing the optimum place for bass traps? The corner created where the ceiling drops down toward the back part of the room would make a nice out of the way place to put some bass traps. However, I'm not sure if this would be an effective location.


Also, I'm on a limited budget, so I'll probably be doing this in phases. As a starting point, I'm thinking I can afford about six 2' x 4' x 2" panels and two or three corner bass absorption traps.


Two other questions while I'm at it...


Is it ok to put absorption panels behind drapes?


I had always heard that carpeted floors are better than wood floors. However, in reading through the first dozen pages of this thread, I see suggestions that a hard surfaced floor is better that carpeting. Can anyone clarify?


Thanks for any help!!











These photos were taken before I started remodeling the room...


----------



## R Harkness

Hey folks,


I'm at the point where I have to decide how much money I have to throw at my HT project and have just received one design for acoustic treatments, from the acoustician I've been working with. I'm just looking for second opinions because this stuff is darned expensive!


Here is an overview of my room, with screen and speakers indicated:











Here is a view from the couch:











The acoustician's design suggests re-building the whole screen wall behind the speakers, with acoustic paneling behind the screen, screen wall, and some low bass traps spread along the floor and over top the screen.


There is an additional suggestion of acoustic panels on the ceiling, filling in the area within the ceiling bulk-head. The general areas of the acoustic treatment are represented in blue:











Here's an image from the screen wall, facing the back of my room:











As the room stands now, the general issues I'm having are a bass lift from the speakers being near the screen wall/room corners and a bit of lumpiness (dips) in the mid-range.


Any opinions on this design for acoustic treatment? It's quite expensive and I'm wondering how much I need to do to get some decent level of benefit. Could I forgo having the whole wall re-done and use traps in the corners or whatever?


Thanks mightily.


Rich H


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14570183
> 
> 
> Is the image below any more helpful? Unfortunatley, it's not drawn to scale or anything. Also, I have't exactly figured out where my surround speakers or sub are going to be placed.
> 
> 
> So, I think I understand that I need some absorption panels on the side walls. What's not clear to me is whether I need some on the front wall as well.
> 
> 
> I'm also thinking some bass traps in some corners. How do I determing the optimum place for bass traps? The corner created where the ceiling drops down toward the back part of the room would make a nice out of the way place to put some bass traps. However, I'm not sure if this would be an effective location.
> 
> 
> Also, I'm on a limited budget, so I'll probably be doing this in phases. As a starting point, I'm thinking I can afford about six 2' x 4' x 2" panels and two or three corner bass absorption traps.
> 
> 
> Two other questions while I'm at it...
> 
> 
> Is it ok to put absorption panels behind drapes?
> 
> 
> I had always heard that carpeted floors are better than wood floors. However, in reading through the first dozen pages of this thread, I see suggestions that a hard surfaced floor is better that carpeting. Can anyone clarify?



Maybe it's the not drawn to scale thing, but I'd move the front speakers away from the side walls as much as possible. Will the center speaker be under/above the display? If so, it will be very close to the front wall. If it is essentially the same as the L & R fronts, it's proximity to the front wall will probably make it sound very different and no longer timbre-matched.


I would definitely treat the front wall as well as the side walls at the first reflection points.


- Jeff


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/14572391
> 
> 
> Hey folks,
> 
> 
> I'm at the point where I have to decide how much money I have to throw at my HT project and have just received one design for acoustic treatments, from the acoustician I've been working with. I'm just looking for second opinions because this stuff is darned expensive!
> 
> 
> As the room stands now, the general issues I'm having are a bass lift from the speakers being near the screen wall/room corners and a bit of lumpiness (dips) in the mid-range.
> 
> 
> Any opinions on this design for acoustic treatment? It's quite expensive and I'm wondering how much I need to do to get some decent level of benefit. Could I forgo having the whole wall re-done and use traps in the corners or whatever?



Did your acoustician say anything about the glass window?


----------



## R Harkness

Yeah, it's not great having it there but he doesn't think it's too big a deal. I can't use curtains over the windows (for various reasons) so I'm sort of stuck with them.


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/14572527
> 
> 
> Yeah, it's not great having it there but he doesn't think it's too big a deal. I can't use curtains over the windows (for various reasons) so I'm sort of stuck with them.



No curtains at all will impact your display selection process and maybe even your viewing hours/pleasure.


----------



## stepyourgameup




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14565199
> 
> 
> I just built a 6" riser out of 2x6s and a 4'x8' piece of plywood. The bottom is hollow. Should I pack it with some R30 insulation to keep it from affecting the bass? It is sitting on carpet with pad on a concrete floor.



Could anyone comment on this? Haven't got the sub yet but I was wanting to finish this riser up this week.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14574353
> 
> 
> Could anyone comment on this? Haven't got the sub yet but I was wanting to finish this riser up this week.



I made mine specifically so that it would resonate. Fortuitously, it does and in the Hertz range of the mid-20's. Explosions, stomping olyphants, whatever, produce a real kick in the pants!


Check the site linked in my sig. Navigate to the "building the riser" section.


----------



## R Harkness




> Quote:
> Originally Posted by *pepar* /forum/post/14573060
> 
> 
> No curtains at all will impact your display selection process and maybe even your viewing hours/pleasure.



I've got that covered: Electric black out shades will be used for the windows.

Besides, I only watch films at night (and any stray light from streetlamps should be blocked by the black-out shades).


Anyway, I hope some of the experts here can have a look at what I posted to give an opinion.


Thanks.


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14574546
> 
> 
> I made mine specifically so that it would resonate. Fortuitously, it does and in the Hertz range of the mid-20's. Explosions, stomping olyphants, whatever, produce a real kick in the pants!
> 
> 
> Check the site linked in my sig. Navigate to the "building the riser" section.



Nice. Question for you. Didn't you want to mount your absorbers about 4" away from the wall?


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14574798
> 
> 
> Nice. Question for you. Didn't you want to mount your absorbers about 4" away from the wall?



Ummm, no. Why?


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14575208
> 
> 
> Ummm, no. Why?



Everything I have read suggests that the more space between your wall and your absorber, the more effective they are. I figured you would know that or am I crazy? If that's incorrect, it sure would make it easier to mount to a wall without having to find a way to space it.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14572497
> 
> 
> Maybe it's the not drawn to scale thing, but I'd move the front speakers away from the side walls as much as possible. Will the center speaker be under/above the display? If so, it will be very close to the front wall. If it is essentially the same as the L & R fronts, it's proximity to the front wall will probably make it sound very different and no longer timbre-matched.
> 
> 
> I would definitely treat the front wall as well as the side walls at the first reflection points.
> 
> 
> - Jeff



How do I determine where to place treatments on the front wall? Above the TV? Below the TV? Right/left of the TV?


Thanks. FYI, I don't have a center channel. I can probably move my speakers another 12 inches or so from the side wall.


Thanks!


----------



## elee532

1. I had always heard that carpeted floors are better than wood floors. However, in reading through the first dozen pages of this thread, I see suggestions that a hard surfaced floor is better that carpeting. Can anyone clarify?


2. My funds are limited, but I would like to add at least a few corner bass traps to my room. How do I determine where I should place them?


3. Is it ok to put absorption panels behind drapes?


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14575354
> 
> 
> Everything I have read suggests that the more space between your wall and your absorber, the more effective they are. I figured you would know that or am I crazy? If that's incorrect, it sure would make it easier to mount to a wall without having to find a way to space it.



Not crazy. I've heard that. The idea is to add some diaphramatic absorption to it. At what frequency it absorbs, i.e. vibrates, is calculable, but not by me or anyone I know. I have bass traps, so I don't need it for bass. And I didn't want the darn things encroaching into my room any further.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14575894
> 
> 
> How do I determine where to place treatments on the front wall? Above the TV? Below the TV? Right/left of the TV?
> 
> 
> Thanks. FYI, I don't have a center channel. I can probably move my speakers another 12 inches or so from the side wall.
> 
> 
> Thanks!



Do the mirror thing. Your L&R front speakers have first reflection points on the front wall.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14575932
> 
> 
> 1. I had always heard that carpeted floors are better than wood floors. However, in reading through the first dozen pages of this thread, I see suggestions that a hard surfaced floor is better that carpeting. Can anyone clarify?



It's not that wood is better than carpet, or vice versa. It depends on the rest of the room and how it is treated. In a room with plaster walls and ceiling, carpet or area rug on the floor might be a good thing. Something else to ponder is the thinking that one should not have two parallel reflective surfaces - anywhere - as that will cause slap echo. Hard ceiling? Absorbant floor. Plaster back wall? Treat the entire front wall. Real home theater designers will use a mix of reflective, absorptive and dispersive treatments distributed throughout the room.



> Quote:
> 2. My funds are limited, but I would like to add at least a few corner bass traps to my room. How do I determine where I should place them?



Corners.







(Do as many as you can; it doesn't matter acoustically where you start.)



> Quote:
> 3. Is it ok to put absorption panels behind drapes?



Sure, the drapes are already absorbing the higher frequencies. Might as well get mid absorption there, too.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14576136
> 
> 
> It's not that wood is better than carpet, or vice versa. It depends on the rest of the room and how it is treated. In a room with plaster walls and ceiling, carpet or area rug on the floor might be a good thing. Something else to ponder is the thinking that one should not have two parallel reflective surfaces - anywhere - as that will cause slap echo. Hard ceiling? Absorbant floor. Plaster back wall? Treat the entire front wall. Real home theater designers will use a mix of reflective, absorptive and dispersive treatments distributed throughout the room.



Is drywall a hard or absorbant surface? My walls are drywall, ceiling is drywall, and floor is carpeted. I need to make a decision about whether to have the carpet restretched or replace with laminate flooring. Any reccomendation?



> Quote:
> Originally Posted by *pepar* /forum/post/14576136
> 
> 
> Sure, the drapes are already absorbing the higher frequencies. Might as well get mid absorption there, too.



So, are you saying that drapes won't impede the panels?


Thanks!


----------



## knight427




> Quote:
> Originally Posted by *pepar* /forum/post/14576062
> 
> 
> Not crazy. I've heard that. The idea is to add some diaphramatic absorption to it. At what frequency it absorbs, i.e. vibrates, is calculable, but not by me or anyone I know. I have bass traps, so I don't need it for bass. And I didn't want the darn things encroaching into my room any further.



A fiberglass panel will have very little absorption due to panel vibrations ("diaphramatic"). I'll try to explain the primary reason airspace behind a panel improves low freq absorption.


Fiberglass and other soft absorbers work by transferring the motion of air particles (sound) into heat. The fibers are pushed back and forth by the air molecules, but lacking a restoring force, the motion of the fibers is highly damped, dissipating the energy into friction/heat.


At a boundary (wall), the sound waves are forced to maximum pressure, which means the air molecules are changing direction (effectively they have no velocity and are not moving). Since the air molecules aren't moving at the wall, the wall is a terrible place for "soft" absorbers. Fortunately, the air molecules are moving with maximum speed at a distance of (wavelength/4) from the wall. For high and mid frequencies, this is close enough to the wall for a 1" or 2" panel to encounter moving air particles. For lower frequencies, you need a thicker absorber or to move the panel out towards the "velocity zone".


I hope that is more helpful than it is confusing.



> Quote:
> Originally Posted by *elee532* /forum/post/14577549
> 
> 
> Is drywall a hard or absorbant surface? My walls are drywall, ceiling is drywall, and floor is carpeted. I need to make a decision about whether to have the carpet restretched or replace with laminate flooring. Any reccomendation?



Yes, it is both. Gypsum will reflect mid and high frequencies, but absorb a fair amount of low freq due to panel vibration. I'd go with carpet since all your other surfaces are hard.



> Quote:
> Originally Posted by *elee532* /forum/post/14577549
> 
> 
> So, are you saying that drapes won't impede the panels?
> 
> Thanks!



I'll step in and say that the drapes will allow low frequencies to pass through with minimal absorption, then hopefully those lower frequencies will get absorbed by the panel (given sufficient thickness and density). You'll get more Abs/$ if you seperate the drapes and panels, but you'll get more balanced absorption across the frequency spectrum if you stack them.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14577549
> 
> 
> Is drywall a hard or absorbant surface? My walls are drywall, ceiling is drywall, and floor is carpeted. I need to make a decision about whether to have the carpet restretched or replace with laminate flooring. Any reccomendation?



The simple answer is that drywall is reflective. A more complete answer, and probably one that you can safely ignore for the purposes of acoustical treatments, is that it is reflective at mids and highs, but has a resonant frequency "somewhere" below those frequencies where it absorbs and then a range of frequencies that it passes. (Think about hearing a booming bass coming through a wall from another room.)



> Quote:
> So, are you saying that drapes won't impede the panels?



Yes. Unless they are vinyl







or metal







, what the curtains do not absorb, they will pass through to the panels.


----------



## pepar




> Quote:
> Originally Posted by *knight427* /forum/post/14578163
> 
> 
> Fiberglass and other soft absorbers work by transferring the motion of air particles (sound) into heat. The fibers are pushed back and forth by the air molecules, but lacking a restoring force, the motion of the fibers is highly damped, dissipating the energy into friction/heat.
> 
> 
> At a boundary (wall), the sound waves are forced to maximum pressure, which means the air molecules are changing direction (effectively they have no velocity and are not moving). Since the air molecules aren't moving at the wall, the wall is a terrible place for "soft" absorbers. Fortunately, the air molecules are moving with maximum speed at a distance of (wavelength/4) from the wall. For high and mid frequencies, this is close enough to the wall for a 1" or 2" panel to encounter moving air particles. For lower frequencies, you need a thicker absorber or to move the panel out towards the "velocity zone".



I was under the impression that the best place to absorb bass was where the molecules are moving their slowest - right at the wall and where all of the frequencies are present - in corners.


I think it's time for some real acousticians to speak up!


----------



## knight427




> Quote:
> Originally Posted by *pepar* /forum/post/14579146
> 
> 
> I think it's time for some real acousticians to speak up!



Define "real acoustician"


----------



## warlord260




> Quote:
> Originally Posted by *warlord260* /forum/post/14439172
> 
> 
> i have a question i hope someone could answer for me.
> 
> my first reflection point for my mains are leather couch one side, leather loveseat other.
> 
> what should i do about this?



would it help to hang panels on the wall over the couches to absorb relections that might bounch off them. they are both right in the line of fire for my first refection points of my mains.

also would it be benificial to put cloth coverings over them, the couches.

in a perfect world i would move them, and hang panels where they are.

anybody know a solutions to this?


----------



## krasmuzik

pepar


you might want to wash that **** of your foot before you stick it in your mouth...


check knight427 profile and do a google search (hint -football). He has a masters degree in architectural acoustics and a BA in physics and worked at very respected firms.

http://www.knightacoustics.com/Corpo...tAcoustics.pdf 


Look closely at GreenGlue test reports - yep it is same guy that was at the test lab.

http://www.soundproofingcompany.com/...414_Report.pdf 


Note to knight427 - usually pros are allowed to indicate such in their .sig to avoid such confusion - the forum just does not like .sig links from those looking to improve their google page rank. As long as you are giving back as much as you get by helping people that would never hire you.



And I would only improve your answer by saying the quarter wavelength is the maximum velocity point - you still have some velocity even at tenth wavelength. Only at half and begin/end of the wave is the velocity zero and pressure max. That is why performance of absorbers "roll-off" in the bass - they don't immediately switch to non-absorbing at some magic frequency. Corners are at maximum pressure - which means pressure traps rather than velocity traps are most effective - but that does not mean a velocity trap cannot have some effect - or that traps are all one type or the other.


----------



## pepar




> Quote:
> Originally Posted by *knight427* /forum/post/14580908
> 
> 
> Define "real acoustician"



Edited my post . . .


. . before reading krazmuzik's.


----------



## pepar




> Quote:
> Originally Posted by *krasmuzik* /forum/post/14581123
> 
> 
> pepar
> 
> 
> you might want to wash that **** of your foot before you stick it in your mouth...



In the spirit of being self-effacing, I'll leave my "real acoustician" comment up. And apply a generous amount of salsa habanero to my foot.



> Quote:
> check knight427 profile and do a google search (hint -football). He has a masters degree in architectural acoustics and a BA in physics and worked at very respected firms.



Honestly, it's not real practical to google every member before participating in a thread discussion.


Isn't the best place for bass traps in corners, and aren't solid superchunk-style traps more effective than a 2" sheet straddling a corner?


----------



## SteveMo




> Quote:
> Originally Posted by *pepar* /forum/post/14581250
> 
> 
> In the spirit of being self-effacing, I'll leave my "real acoustician" comment up. And apply a generous amount of salsa habanero to my foot.
> 
> 
> 
> Honestly, it's not real practical to google every member before participating in a thread discussion.
> 
> 
> Isn't the best place for bass traps in corners, and aren't solid superchunk-style traps more effective than a 2" sheet straddling a corner?



Corners are not always the _only_ best. For example, I could significantly treat 80Hz - 150Hz by placing panels at the rear side walls. It would work very well. Yes the superchunks are superior.


- Steven


THX Tech I


----------



## knight427

@krasmuzik: You spoiled my fun! Also, I sort of glossed over the (1/4) wavelength thing in the interest of brevity, but I did hint at it.


@pepar: No worries, I am actually looking for a good reference to support my explanation, there are none easily found on the internet as everyone seems content to just blindly accept conventional wisdom w/o a rigorous explanation. I have something from a book, but I'll have to type it out when I have a chance.


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/14581510
> 
> 
> Corners are not always the _only_ best. For example, I could significantly treat 80Hz - 150Hz by placing panels at the rear side walls. It would work very well. Yes the superchunks are superior.
> 
> 
> - Steven
> 
> 
> THX Tech I



Some - many - of us are using rooms that are already small-ish and standing panels off the wall 4" - 6" (or whatever) not only encroaches upon valuable space, but can be an obstacle that people using the theater must avoid hitting. Is it not easier to achieve any given level of bass absorption in a corner than mid-wall? If one is already using panels at the first reflection points, how much additional LF absorption can be gained by "optimizing the air gap" between the panels and the wall?


----------



## amirm




> Quote:
> Originally Posted by *knight427* /forum/post/14578163
> 
> 
> Yes, it is both. Gypsum will reflect mid and high frequencies, but absorb a fair amount of low freq due to panel vibration.



Indeed.... leaving one to wonder what to do with sound isolation in presence of such an effect. Double drywall is surely going to make the panel more stiff, making it less of an absorber for low frequencies.


Advice I have gotten is to put double-drywall on the outside wall (and don't use one at all in front of concrete foundation wall). It doesn't work as well that way since it is not against the source of the noise but seems like an interesting compromise.


What do you think?


----------



## SteveMo

Yes that is why I don't have panels there. Although they would work good, it is just not practical to have some GIK 244 traps hanging on the walls with one right next to a door. Not sure about the air gap improvement. I moved my speakers already so to re-measure after spacing them might not show a very good example with my measurement. I could show you anyway but you would have to keep in mind that there is no system, just a computer,mic, amp and a speaker... Did you want to see a before/after? I can tell you that I can hear an immediate difference.


Here is how I spaced them with Velcro, furring strips, and the supplied clips. They stick right to the carpet walls up front. They would fall off the walls or become loose and hang crooked otherwise. The velco only method (on texture drywall) quit working after I stuffed insulation around the corners of my ceiling. I was amazed when one fell.


This is working fine so far and has survived plenty of abuse. I will be redoing the riser soon I think (raising some seats) so that a ceiling node improves with all my subwoofers located in the corners. It's the best I have heard yet. I will have to see if they still stay on the walls but something tells me they will be fine with less ringing around 20Hz - 30Hz. The lowest I have seen my 2" first reflection panels effecting was 40Hz, but I have not tested with the newer install. I'm still stuck enjoying the subwoofers and testing those.


----------



## CJO




> Quote:
> Originally Posted by *krasmuzik* /forum/post/14581123
> 
> 
> And I would only improve your answer by saying the quarter wavelength is the maximum velocity point - you still have some velocity even at tenth wavelength.



So, for a 20 Hz sound wave, you'd want to try have your absorber approximatly 14' from the boundary? I'm glad it is still somewhat effective at 5'!


CJ


----------



## pepar




> Quote:
> Originally Posted by *amirm* /forum/post/14581708
> 
> 
> Indeed.... leaving one to wonder what to do with sound isolation in presence of such an effect. Double drywall is surely going to make the panel more stiff, making it less of an absorber for low frequencies.
> 
> 
> Advice I have gotten is to put double-drywall on the outside wall (and don't use one at all in front of concrete foundation wall). It doesn't work as well that way since it is not against the source of the noise but seems like an interesting compromise.
> 
> 
> What do you think?



Hi Amir,










Do you know about building two walls that don't touch, or touch only minimally? Plus, there is material that can be included in the wall construction that can help isolate. An example is here .


----------



## amirm




> Quote:
> Originally Posted by *pepar* /forum/post/14581927
> 
> 
> Hi Amir,



Hello pepar







. Good to see you in another context.



> Quote:
> Do you know about building two walls that don't touch, or touch only minimally? Plus, there is material that can be included in the wall construction that can help isolate. An example is here .



Yes I do although I had not seen the above product (so thanks for that!).


The issue is that this and other similar techniques are about decoupling and mechanical transmission of sound. It doesn't stop the drywall from flexing and with it, transmit the sound to the other side. Hence the usual suggestion of using double drywall and green glue between them in addition to such isolation.


My point was that the very act of attempting to stop the noise from going into adjacent cavity by using twice as much mass, is going to make it less of an absorber (with or without green glue between them). The two goals appear in conflict here.


----------



## knight427




> Quote:
> Originally Posted by *amirm* /forum/post/14581708
> 
> 
> Indeed.... leaving one to wonder what to do with sound isolation in presence of such an effect. Double drywall is surely going to make the panel more stiff, making it less of an absorber for low frequencies.
> 
> 
> Advice I have gotten is to put double-drywall on the outside wall (and don't use one at all in front of concrete foundation wall). It doesn't work as well that way since it is not against the source of the noise but seems like an interesting compromise.
> 
> 
> What do you think?



I guess I'd rather invest in the sound isolation and rely on corner bass traps for LF absorption. Of course, the corner bass trap may not be as effective at ultra-low frequencies, but I have a hard time seeing how you design your gypsum walls to have an optimal amount of LF absorption given the resonant issues of the wall panel, and the fact that your room may not even be able to fit 1/2 wavelength @20 Hz. In my opinion, it is in-calculable. But if someone with vast amounts of experience tells you it makes a positive difference, then I guess I would defer to their experience.


----------



## R Harkness

Hi folks,


Since this one expense is holding me from pulling all the triggers on my HT, I'm hoping I can get the attention of a Pro here. My post from the last page asking thoughts on my acoustician's suggested plan for my room:

http://www.avsforum.com/avs-vb/showt...1#post14572391


----------



## pepar

knight427 makes a good point, Amir. Design the walls for maximum isolation and then use acoustical treatments for quality sound in the room. Then there is no conflict.


As a side project, you could devote your spare time to solving the equation of isolating/sound absorbing walls.


----------



## SteveMo




> Quote:
> Originally Posted by *knight427* /forum/post/14582129
> 
> 
> I guess I'd rather invest in the sound isolation and rely on corner bass traps for LF absorption. Of course, the corner bass trap may not be as effective at ultra-low frequencies, but I have a hard time seeing how you design your gypsum walls to have an optimal amount of LF absorption given the resonant issues of the wall panel, and the fact that your room may not even be able to fit 1/2 wavelength @20 Hz. In my opinion, it is in-calculable. But if someone with vast amounts of experience tells you it makes a positive difference, then I guess I would defer to their experience.



My recepie is staggered studs that are liquid nailed to a concrete wall with felt on the studs between the 1/2" wall at a specific height. I also have a partition wall on the other side that is 1/2" DW, R19 pink, then 5/8 DW in the front of the room. The back of the rooms walls are 1/2" with R14 same as the other walls. My walls are not weight bearing and nothing in the room is attached to them including the ceiling. The partition wall is also offset. That is my isolation/walls.


My seats all measure practically the same. Here is -10dB at my worst seat.











Do you see anything wrong with what I did? Sounds great.


----------



## SteveMo

That is ok knight427. Nobody has commented on that one in years.


----------



## knight427

Hey Steve,


I browsed through some of your pictures trying to get a better idea of your design. Sounds like you did box-in-box construction.


I saw some of the comments on your photos where it appears you did a vibration survey of the studs before mounting the gypsum. What exactly did you do to treat these areas of vibration?


You also mentioned "felt on the studs between the 1/2" wall at a specific height". I'm not sure what you meant by this, nor am I familiar with using felt as part of an isolation system. Perhaps you can elaborate more on what you did, and why you did it.


Finally, what are the dimensions of your room?


----------



## elee532




> Quote:
> Originally Posted by *knight427* /forum/post/14578163
> 
> 
> Yes, it is both. Gypsum will reflect mid and high frequencies, but absorb a fair amount of low freq due to panel vibration. I'd go with carpet since all your other surfaces are hard.



Thanks!



> Quote:
> Originally Posted by *knight427* /forum/post/14578163
> 
> 
> I'll step in and say that the drapes will allow low frequencies to pass through with minimal absorption, then hopefully those lower frequencies will get absorbed by the panel (given sufficient thickness and density). You'll get more Abs/$ if you seperate the drapes and panels, but you'll get more balanced absorption across the frequency spectrum if you stack them.



I'm not clear what you mean by "seperate the drapes and panels" vs. "stack them." Sorry if I'm not understanding something simple, but would you mind explaining this to me?


Thanks!


----------



## elee532




> Quote:
> Originally Posted by *SteveMo* /forum/post/14581510
> 
> 
> Yes the superchunks are superior.



Wow, I was just going to ask which was the better option. Thanks for asking the question Pepar and thanks for answering it SteveMo.


When putting superchunks in a corner, is there a minimum size that they need to be? I'm thinking about trying to create something like the photo below from floor to ceiling. I have a 6" ledge about half way up the wall. I was planning to use 17" x 17" x 24" chunks on the top half of the wall and then small triangles on the bottom half to account for the 6" ledge. Is this an acceptable size (FYI, the room is approx. 9.5' x 17.5').


BTW, can anyone point me to some step-by-step directions showing how the fabric might be attached in a corner setup like the one below?


Thanks!


----------



## knight427




> Quote:
> Originally Posted by *elee532* /forum/post/14584948
> 
> 
> I'm not clear what you mean by "seperate the drapes and panels" vs. "stack them." Sorry if I'm not understanding something simple, but would you mind explaining this to me?
> 
> Thanks!



By "stack", I meant put the drapes in front of the panels. Then separating them just means to hang the panels and drapes in different locations so there is no overlap.


----------



## stepyourgameup




> Quote:
> Originally Posted by *elee532* /forum/post/14585177
> 
> 
> Wow, I was just going to ask which was the better option. Thanks for asking the question Pepar and thanks for answering it SteveMo.
> 
> 
> When putting superchunks in a corner, is there a minimum size that they need to be? I'm thinking about trying to create something like the photo below from floor to ceiling. I have a 6" ledge about half way up the wall. I was planning to use 17" x 17" x 24" chunks on the top half of the wall and then small triangles on the bottom half to account for the 6" ledge. Is this an acceptable size (FYI, the room is approx. 9.5' x 17.5').
> 
> 
> BTW, can anyone point me to some step-by-step directions showing how the fabric might be attached in a corner setup like the one below?
> 
> 
> Thanks!



How much is it gonna cost you to do the superchunk thing?


----------



## knight427




> Quote:
> Originally Posted by *knight427* /forum/post/14578163
> 
> 
> link to original post



I felt compelled to provide some citation for my explanation of how sound absorption works. The following is the best I could find for now. It does not specifically support my claim that the absorber must occupy some space away from the wall because it needs to interact with molecules in motion (or velocity zone as I called it), but I think if you put the two paragraphs together, it essentially says the same thing.


All typos are my own, I hope this much text falls under fair use.

_Handbook of Acoustical Measurements and Noise Control

Third Edition

Cyril M. Harris


Chapter 30

pgs 30.1-30.2


The element which accounts for the dissipation of sound energy in most acoustical materials is a layer of highly porous material (at least ½ in thick) in which the pores intercommunicate throughout. The pores may be formed by felted mineral or fiberglass, by the interstices between small granules, or by a foamed composition in which the solidified bubbles interconnect throughout the material. When a sound wave enters the porous material, the amplitude of vibration of the air molecules is progressively damped out by friction against the surfaces of the fibers or particles forming the porous structure. This friction acts as an acoustical resistance whose value depends on the resistance of the material to direct airflow; such friction depends only slightly on frequency.


Another factor which affects sound absorption, principally in the low-frequency range, is the depth of airspace between the face of the material and a rigid backing surface behind it. The volume of air between these two surfaces includes both the air in the pores of the material and any airspace between the material and its backing. The latter may vary from zero, when the material is secured directly to a rigid backing, to 3 ft or more in the case of suspended acoustical ceilings. When the total depth is less than about one-fourth wavelength, the low-frequency absorption coefficient of the material decreases with decreasing frequency.
_


----------



## SteveMo




> Quote:
> Originally Posted by *knight427* /forum/post/14584674
> 
> 
> Hey Steve,
> 
> 
> I browsed through some of your pictures trying to get a better idea of your design. Sounds like you did box-in-box construction.
> 
> 
> I saw some of the comments on your photos where it appears you did a vibration survey of the studs before mounting the gypsum. What exactly did you do to treat these areas of vibration?
> 
> 
> You also mentioned "felt on the studs between the 1/2" wall at a specific height". I'm not sure what you meant by this, nor am I familiar with using felt as part of an isolation system. Perhaps you can elaborate more on what you did, and why you did it.
> 
> 
> Finally, what are the dimensions of your room?



There were alot of studs touching the concrete walls. I went around the room hammering on them and marking the places with marker. I also found that many of the 2X4's had a certain tone to them when hit kind of like a tunning fork. The frequency at which they vibrated was very familiar to me as my previous HT was a basement with 2X4 wall construction. This was the flanking noise I heard across my walls at just above ear level. I would end up watching the wall and tracking the vibration move horizontally to each corner in my room. I decided since I had not been able to use the wood I wanted and I knew that I was in for trouble, to secure every 2X4 directly to the concrete using the liquid nails. I could not get isolation clips or anything else such as green glue, so I put strips of felt about 4 feet high starting just bellow ear level, and ending at around 6 feet high. The drywall was not screwed in at these areas. The partiton wall for the room within a room went in mostly as planned but I have since modified it by moving the equipment closet door out of the HT, and into the lobby. This is how it got the different thickness wall on the other side. The area where the door was got 2X2's that attached to new 2X4's.


Besides the 2X4's being nailed together, they are all glued at every joint using painters caulk or silicone. All sconces, light switches, electrical boxes, and anything else inside the concrete structure got caulk also. There is caulk filled between the door and frame of the HT door as well. Any plywood got wood glue. Dozens of tubes.


The crown molding is attached using deck screws only except for the molding on the carpet which attached using Velcro except for one peice next to 2X4 I used slicone on. The basebord is attached using trim nails. My quarter round trim at the top of the wall where the carpet is (next to the crown molding) only a friction fit as so are the other ones next to my screen. They look nice and neat without holes in them.


Basically I anticpated everything in the room to resonate and vibrate uncontrollably. What I was wondering if somehow by leaving the walls so flexable, and everything else very solid, I did something wrong? It seems most people here want very solid heavy walls but occasionally add additional means to make them decoupled. Someone was telling me that walls in a concrete room are supposed to be flexable, but I wanted to see if I get an opinion on if my method was practical or not. The builder (place was a last minute thought that was built in weeks) removed them, but I put them back. I saw one in the wall next to a stud when I was redoing the closet area and there was no space between it and drywall.


The ceiling has no drywall but is instead a layer of steel and concrete, with a Ceilume tile attached to the joist using ceiling link. I filled the tiles using "back panels" which were desingned to add more absorption, but I found that not to work very well. I filled the front of the room with them (2 layers) with pink inside and they sound much better. The drop ceiling above in my garage rattles. So does the garage door opener, the shelves etc. Sconces outside the house, the deck, candy counter, dishes in the sink (with the door open) all rattle as well. I think I may have done a decent job of isolation. I was playing WOTW at 5:00am and didn't wake up anyone.











The concrete area is 20 X 20 X 8' 7". That is an aprox on the ceiling height. The room including the ceiling tiles (not relevant for LF) is 20' X 13' 6" X 7' 6". There is also room treatments.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14585177
> 
> 
> When putting superchunks in a corner, is there a minimum size that they need to be? I'm thinking about trying to create something like the photo below from floor to ceiling. I have a 6" ledge about half way up the wall. I was planning to use 17" x 17" x 24" chunks on the top half of the wall and then small triangles on the bottom half to account for the 6" ledge. Is this an acceptable size (FYI, the room is approx. 9.5' x 17.5').
> 
> 
> BTW, can anyone point me to some step-by-step directions showing how the fabric might be attached in a corner setup like the one below?
> 
> 
> Thanks!



Follow the 4/29/08 link in my sig and then on to the StudioTip Forum link. There you will find design and construction information. As for attaching fabric, I believe that there is a step-by-step where you found the image.


I went for the 17x17x24 version of the SSC traps.


- Jeff


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14585372
> 
> 
> How much is it gonna cost you to do the superchunk thing?



I paid about $10-$12 per sheet in bulk for OC 703. Each sheet makes 1.3 lineal feet (16") of 17x17x24 SuperChunk trap. Check the link in my sig.


- Jeff


----------



## GatorSteve

Couple of quick questions - (1) I have easy access to either Knauf EI-475 or EI-800 but they both have FSK. In making the SSC's for the bass traps, will the FSK be a problem or should I rip it off or find a different material?, (2) I will have an AT screen mounted to a false wall 2 1/2' from the front wall. As far as the front and side wall treatments, should I remove the FSK or just mount the FSK against the wall or again find another product?


Steve


----------



## pepar




> Quote:
> Originally Posted by *GatorSteve* /forum/post/14587045
> 
> 
> Couple of quick questions - (1) I have easy access to either Knauf EI-475 or EI-800 but they both have FSK. In making the SSC's for the bass traps, will the FSK be a problem or should I rip it off or find a different material?, (2) I will have an AT screen mounted to a false wall 2 1/2' from the front wall. As far as the front and side wall treatments, should I remove the FSK or just mount the FSK against the wall or again find another product?



If you check here , you will see the difference between FSK and un-faced. But that is for flat panels, not chopped into triangles. I don't recall seeing any SSC testing with facing. You could go on the StudioTips forum and ask.


For lining the false wall cavity, I would place the Kraft against the wall.


----------



## GatorSteve




> Quote:
> Originally Posted by *pepar* /forum/post/14588207
> 
> 
> If you check here , you will see the difference between FSK and un-faced. But that is for flat panels, not chopped into triangles. I don't recall seeing any SSC testing with facing. You could go on the StudioTips forum and ask.
> 
> 
> For lining the false wall cavity, I would place the Kraft against the wall.



I have searched and searched and have not seen any mention of whether the facing would affect the results in any way for the SSC. I will go over there and ask. Thanks


Steve


----------



## R Harkness

Gotta bump my post again:




> Quote:
> Originally Posted by *R Harkness* /forum/post/14572391
> 
> 
> Hey folks,
> 
> 
> I'm at the point where I have to decide how much money I have to throw at my HT project and have just received one design for acoustic treatments, from the acoustician I've been working with. I'm just looking for second opinions because this stuff is darned expensive!
> 
> 
> Here is an overview of my room, with screen and speakers indicated:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here is a view from the couch:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The acoustician's design suggests re-building the whole screen wall behind the speakers, with acoustic paneling behind the screen, screen wall, and some low bass traps spread along the floor and over top the screen.
> 
> 
> There is an additional suggestion of acoustic panels on the ceiling, filling in the area within the ceiling bulk-head. The general areas of the acoustic treatment are represented in blue:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here's an image from the screen wall, facing the back of my room:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> As the room stands now, the general issues I'm having are a bass lift from the speakers being near the screen wall/room corners and a bit of lumpiness (dips) in the mid-range.
> 
> 
> Any opinions on this design for acoustic treatment? It's quite expensive and I'm wondering how much I need to do to get some decent level of benefit. Could I forgo having the whole wall re-done and use traps in the corners or whatever?
> 
> 
> Thanks mightily.
> 
> 
> Rich H


----------



## pepar

Rich, just a thought here, perhaps the reason that no one has offered a second opinion - not even after three bumps - is that your situation is too complex to render an opinion without taking measurements and/or getting into it on a level not possible on a forum and for free.


Just a thought.


- Jeff


----------



## Ethan Winer




> Quote:
> Originally Posted by *GatorSteve* /forum/post/14587045
> 
> 
> In making the SSC's for the bass traps, will the FSK be a problem or should I rip it off or find a different material?



FSK is good for corner bass traps, but not for absorbers at reflection points. More here:

Density Report 


--Ethan


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14586877
> 
> 
> Follow the 4/29/08 link in my sig and then on to the StudioTip Forum link. There you will find design and construction information.



Actually Jeff, it was the your "Pepar´s Home Theater Upgrade Project" website and the link I found there to the Studiotips SuperChunk page that made me aware of the "Superchunk" approach. Thanks!!



> Quote:
> Originally Posted by *pepar* /forum/post/14586877
> 
> 
> As for attaching fabric, I believe that there is a step-by-step where you found the image.



The only mention that I could find about attaching the cloth was here:
_A light frame covered in cloth and mounted in the corner to cover the panels is then installed to finish off the look of the appliance. Or a series of face panels could be cloth covered and mounted over the stacked triangles to enlarge the volume of the device and provide the finished face._
I was hoping for something a bite more detailed. Are you aware of anything that might help an amatuer?



> Quote:
> Originally Posted by *pepar* /forum/post/14586877
> 
> 
> I went for the 17x17x24 version of the SSC traps.



So, the chunks on the top half of my wall will be 17" x 17" x 24". However, due to the 6" ledge on the bottom half of the wall, the chunks on the bottom half would only be about 6" x 6" x 9". Is this too small to be effective?


Thanks.


----------



## Lonely Raven

First off, I believe this is my first post here. I've been pursuing this thread for a bit, looking for ideas and some guides...and I'm hoping I can get some suggestions as to what pitfalls to look out for with my setup from those of you with more experience than me. My fiance and I just moved into this house a few months ago, and I'm focusing on the Home Theater setup. I'm at the point where my speakers should arrive soon, and I'd like to get a basic idea for treatment layout. I'm familiar with absorption and diffusion as I've built several from the old Decware plans. I still have some of my first Decware Bass Traps and Quadratic Diffusers I built 10 years ago, but I'm looking into making some OC703 absorbers and super chunks and maybe a few skyline diffusers.


Secondly, forgive the Paint drawing. I got really fed up with trying to figure out Room Arranger, and I whipped this up in 25 minutes (about how long I wasted just starting a room in Room Arranger). The drawing is somewhat scaled having whipped it up by eye. But it's close enough for Rock n Roll.











* EDIT: Drawing is up now!



So I'm working with an L Shaped Living Room Dining Room combo. I drew in the kitchen to the right of the main seating, because I have a very large opening cut between the kitchen and living room with 3 bar stools there (three circles behind big L shaped opening in wall). And open doorways between the living room and kitchen, and dining room and kitchen (bright green)


The X marks my seat on the big leather theater chairs with a small leather couch to the left. Behind the main seating is a stair railing and stairs down to the lower level and front door of the house.


The light blue on the left wall and right wall are Windows which will have blackout drapes completely blocking out light (going almost floor to ceiling).


The viewing wall has an 84" projection screen, two glass gear racks under the screen, and my Elemental Design Home Theater speakers. The black box on the left is a 36" X 36" folded horn.


I absolutely plan on testing the room and seeing how this Home Theater responds. I have the RAW program and a Mackie Mixer, and I already have a HTPC connection to my receiver. I just need to order the Behringer ECM 8000 online since I can't find it locally (wasted most of the morning looking locally).


As it stands now, I have a couple of concerns I figure I'll have to deal with.


1) Left Speaker too close to left Corner.


2) Wide open (asymmetrical) right half


3) I have major flutter echo front to back that is terribly obvious with just clapping.


4) limited subwoofer placement due to its size. Though I suppose I could put it on edge so instead of being 36" X 36" table, it would be a very tall and wide...something...


I don't expect a complete diagnostic of my room, just some tips as to what to look out for, and how to correct or at least tweak the problems I have with this room setup.


After reading up in the thread here, and reading on other people's theater builds I'm thinking...


1) portable diffusers to left and right of mains to help make the room sound symmetrical


2) Super Chunks in front left, front right, and corner between dining room and kitchen.


3) If possible without making the room look trashy, Super chunks along the ceiling sides and rear and maybe some of the front.


4) cloud at ceiling first reflection point?


5) skyline diffusers or absorbers on huge open back wall behind main seating, and possibly on side walls under proposed spots for rear channels.


If this is too much of a post for this ongoing thread, I'll start my own, just say so and I'll take care of it.







Any and all help is greatly appreciated!


----------



## elee532




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14585372
> 
> 
> How much is it gonna cost you to do the superchunk thing?



I'm not sure yet. I don't know how many I need and haven't figured out where i'm going to buy materials.


----------



## elee532

Any general rule re: the amount of bass trapping needed in a room?


I'm planning to build some superchunks from floor to ceiling in the two front corners and one rear corner (no room in the 4th corner - there is a door).


Will this be enough?


The next two locations, if needed, would be the front wall-ceiling edge and the edge where the ceiling drops down by 13" (see photo below).











My room is about 9.5' x 17.5' (more pictures in post #3718).


----------



## bpape

The amount required will be determined by the room size, room construction, furniture, # of people, and usage of the space, It's difficult to get too much in most cases.


As a general rule of thumb, if you can do the front 2 corners floor to ceiling and deal with potential bass nulls off the rear wall, that's a good start and certainly never going to be too much. Then we have to deal with more specific things like SBIR, positional issues to assist with frequency response, etc.


Bryan


----------



## elee532




> Quote:
> Originally Posted by *bpape* /forum/post/14608825
> 
> 
> The amount required will be determined by the room size, room construction, furniture, # of people, and usage of the space, It's difficult to get too much in most cases.
> 
> 
> As a general rule of thumb, if you can do the front 2 corners floor to ceiling and deal with potential bass nulls off the rear wall, that's a good start and certainly never going to be too much. Then we have to deal with more specific things like SBIR, positional issues to assist with frequency response, etc.
> 
> 
> Bryan



Thanks Bryan. Can you elaborate on what you mean by "deal with potential bass nulls off the rear wall?" Do you mean corner traps in rear corner or more like a GIK Monster Bass Trap on the rear wall?


Also, do you see any value in making a trap in that corner where the ceiling drops down? It would end up being like a 12" x 12" x 17" corner trap. I could run it the full 9.5' width of the room. Are those dimensions even large enough to have an impact?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14600594
> 
> 
> Actually Jeff, it was the your "Pepar´s Home Theater Upgrade Project" website and the link I found there to the Studiotips SuperChunk page that made me aware of the "Superchunk" approach. Thanks!!



Glad to help. I remember when I started planning my theater and _devouring_ every enthusiast website I could find.



> Quote:
> The only mention that I could find about attaching the cloth was here:
> _A light frame covered in cloth and mounted in the corner to cover the panels is then installed to finish off the look of the appliance. Or a series of face panels could be cloth covered and mounted over the stacked triangles to enlarge the volume of the device and provide the finished face._
> I was hoping for something a bite more detailed. Are you aware of anything that might help an amatuer?



I think you are on your own. After all, this is a *D*o-*I*t-*Y*ourself project. You'll have to use a little ingenuity! FWIW, when I return to working on my theater, I am adding more SSC traps to the rear of the room which will be visible and therefore need to be "finished" and aesthetically pleasing. Maybe I can copy what you come up with?











> Quote:
> So, the chunks on the top half of my wall will be 17" x 17" x 24". However, due to the 6" ledge on the bottom half of the wall, the chunks on the bottom half would only be about 6" x 6" x 9". Is this too small to be effective?



If you have the room (and $$$), you could go with the 24x24x34 version . . .


----------



## Lonely Raven

Anyone in the Chicagoland area (preferrably western suburbs) know where I can pick up some OC703?


Is there a listing or thread somewhere in the forums where we have mabey compiled information of good places to pick up OC703?


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14611413
> 
> 
> Anyone in the Chicagoland area (preferrably western suburbs) know where I can pick up some OC703?
> 
> 
> Is there a listing or thread somewhere in the forums where we have mabey compiled information of good places to pick up OC703?


 http://www.spi-co.com/servicecenterd...y.cfm?state=IL


----------



## T Morris




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14611413
> 
> 
> Anyone in the Chicagoland area (preferrably western suburbs) know where I can pick up some OC703?
> 
> 
> Is there a listing or thread somewhere in the forums where we have mabey compiled information of good places to pick up OC703?



Not sure how close the location is to what you re looking for but I bought my 2 cases of OC703 24X48X2 from these folks.

http://www.risris.com/Contact-Us/


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14611243
> 
> 
> Glad to help. I remember when I started planning my theater and _devouring_ every enthusiast website I could find.



Indeed!











> Quote:
> Originally Posted by *pepar* /forum/post/14611243
> 
> 
> Maybe I can copy what you come up with?



I'll certainly share if I come up with anything good.











> Quote:
> Originally Posted by *pepar* /forum/post/14611243
> 
> 
> If you have the room (and $$$), you could go with the 24x24x34 version . . .



So, I'm thinking 24x24x34 on the top half of the wall and 17x17x24 on the bottom half. Any reason this wouldn't work?


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14611838
> 
> 
> So, I'm thinking 24x24x34 on the top half of the wall and 17x17x24 on the bottom half. Any reason this wouldn't work?



Sure. Actually I was thinking the stack would be the 24x24x34 on top and keep that "line" to the floor notching out whatever is necessary to accommodate the encroaching ledge or whatever it is that protrudes.


----------



## Lonely Raven




> Quote:
> Originally Posted by *pepar* /forum/post/14611420
> 
> http://www.spi-co.com/servicecenterd...y.cfm?state=IL





> Quote:
> Originally Posted by *T Morris* /forum/post/14611478
> 
> 
> Not sure how close the location is to what you re looking for but I bought my 2 cases of OC703 24X48X2 from these folks.
> 
> http://www.risris.com/Contact-Us/



Thanks guys. I've sent an E-mail to both to see who's closer and can give me a good deal on the OC703.


----------



## Lonely Raven

New Question that I've not seen come up exactly (Granted I didn't read every post out of 127 pages).


For OC703 diffusers, does the cover material have to be acoustically transparent? Or can I wrap in whatever cloth I like the looks of?


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14612909
> 
> 
> New Question that I've not seen come up exactly (Granted I didn't read every post out of 127 pages).
> 
> 
> For OC703 diffusers, does the cover material have to be acoustically transparent? Or can I wrap in whatever cloth I like the looks of?



It only needs to NOT be reflective. But I used Guilford of Maine (GOM) acoustically transparent cloth.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14612040
> 
> 
> Sure. Actually I was thinking the stack would be the 24x24x34 on top and keep that "line" to the floor notching out whatever is necessary to accommodate the encroaching ledge or whatever it is that protrudes.



Thanks!


BTW, here's another DIY project that me some ideas for covering up the absorbers .


----------



## warlord260




> Quote:
> Originally Posted by *warlord260* /forum/post/14439172
> 
> 
> i have a question i hope someone could answer for me.
> 
> my first reflection point for my mains are leather couch one side, leather loveseat other.
> 
> what should i do about this?



i have asked 4 times i think.

was wondering.....


----------



## warlord260




> Quote:
> Originally Posted by *warlord260* /forum/post/14581102
> 
> 
> would it help to hang panels on the wall over the couches to absorb relections that might bounch off them. they are both right in the line of fire for my first refection points of my mains.
> 
> also would it be benificial to put cloth coverings over them, the couches.
> 
> in a perfect world i would move them, and hang panels where they are.
> 
> anybody know a solutions to this?



2nd bump

i am not a leper


----------



## CJO




> Quote:
> Originally Posted by *warlord260* /forum/post/14614753
> 
> 
> i have asked 4 times i think.
> 
> was wondering.....



Do you have a diagram?


CJ


----------



## stepyourgameup




> Quote:
> Originally Posted by *warlord260* /forum/post/14614758
> 
> 
> 2nd bump
> 
> i am not a leper



move the couches out of the way.










I would cover them with an accoustic absorbing blanket or sumsuch.


----------



## elee532




> Quote:
> Originally Posted by *warlord260* /forum/post/14614758
> 
> 
> 2nd bump
> 
> i am not a leper



I've never tried this product (nor any acoustical treatment yet, for that matter







), but maybe this is what you are looking for:

http://www.realtraps.com/p_cover.htm


----------



## javadoc

I'm thinking really simply but wouldn't the ugly bags of mostly water sitting on said couches while watching the movie absorb the sound well enough?


Also, I was looking at some really cool metal frames yesterday and I can't for the life of me find the website again. Does anyone have the link? They were decorative and had some designs cut into the frames.


----------



## Dennis Erskine

...that would be salt water bags.


----------



## blackbelt

Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.


----------



## stepyourgameup




> Quote:
> Originally Posted by *blackbelt* /forum/post/14626853
> 
> 
> Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.



I assume it would help with higher freq. but not low, could be wrong of course.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *blackbelt* /forum/post/14626853
> 
> 
> Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.



I hope this isn't too brutal an answer but....


There are so many variables to take into consideration that your carpet idea is far from practical.


Of course, if you were to build, then test it and post your results it might make for an interesting read. But the first questions you will get are:

1) which carpet

2) what pile

3) what was the density

4) which manufacturer,

5) did you use the pad,

6) which pad, etc., etc., etc.


I mean really..... there are over a thousand different carpets out there when just looking at density, depth, loop/cut loop before they add dyes for color.


Answers such as "standard carpet" will not cut it.


----------



## pepar




> Quote:
> Originally Posted by *blackbelt* /forum/post/14626853
> 
> 
> Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.



But blackbelt, expensive and hard to find is all part of the suffering that we do for our art, er . . home theaters.









http://www.spi-co.com/servicecenterd...y.cfm?state=MO


----------



## SteveMo




> Quote:
> Originally Posted by *blackbelt* /forum/post/14626853
> 
> 
> Sorry if this has been said already. Has anyone tried to use carpet instead of oc 703 boxed with cloth around it? Does that work at all? Oc 703 is expensive and hard to find unless you order it.



Yes I have tried carpet with cloth around it. There were also some tiles laying under it there. I tried using outdoor/indoor carpet. It was the plush kind not the stiff stuff. I put about a 15' X 5' roll in the front right corner of my room in the ceiling extending out into the length of the room. The results were not good.


----------



## blackbelt

Hmm thanks for the responses, and the info stevmo. I am just looking for something to try. I have seen the link for spi before but thanks again pepar. A local home theater store said that they use sound board with cloth material around it. I did not get a chance to listen to the room they had it in as they were changing things around the store. I might give it a try.


----------



## pepar




> Quote:
> Originally Posted by *blackbelt* /forum/post/14628442
> 
> 
> Hmm thanks for the responses, and the info stevmo. I am just looking for something to try. I have seen the link for spi before but thanks again pepar. A local home theater store said that they use sound board with cloth material around it. I did not get a chance to listen to the room they had it in as they were changing things around the store. I might give it a try.



"Sound board?"


----------



## SteveMo

Sound board is very expensive


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/14629764
> 
> 
> Sound board is very expensive



OK, but what is it?


----------



## blackbelt

I think ( correct me if I am wrong) It is the stuff you put behind drywall for sound insulation. Really firm material black I think.


----------



## pepar




> Quote:
> Originally Posted by *blackbelt* /forum/post/14629909
> 
> 
> I think ( correct me if I am wrong) It is the stuff you put behind drywall for sound insulation. Really firm material black I think.



To look at it's specs, we'd need to know the manufacturer and product name.


----------



## SteveMo

It is a product I found at an insulation sales store. They said they sold it to manufactor facilities and they wanted around $150.00 a sheet. It is the industrial equivalant to acoustimat.


----------



## stepyourgameup

hooray, I just found some John Mansville with the foil backing locally for $7.20 a sheet. Time to do some bass traps.
























I plan on 4" corner traps and 1" reflection traps. Is that ok? Is 1" enough?


Never mind, I figured it out.


----------



## Lonely Raven




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14633297
> 
> 
> hooray, I just found some John Mansville with the foil backing locally for $7.20 a sheet. Time to do some bass traps.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I plan on 4" corner traps and 1" reflection traps. Is that ok? Is 1" enough?
> 
> 
> Never mind, I figured it out.



I got a car load of the John Mansville 814 I think it was. $1 a square foot for the 2" stuff.


I'm still looking for cloth I like to wrap these in...or maybe just wimping out and buying some of the pre made bags...but I'd much rather do something custom.


----------



## stepyourgameup




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14635094
> 
> 
> I got a car load of the John Mansville 314 I think it was. $1 a square foot for the 2" stuff.
> 
> 
> I'm still looking for cloth I like to wrap these in...or maybe just wimping out and buying some of the pre made bags...but I'd much rather do something custom.



Save your money and make your own. I've seen some premades for like $25 a piece.


----------



## blackbelt

Do you have to use oc 703? Or will any r-? insulation do? faceless or not?


----------



## Dan Woodruff




> Quote:
> Originally Posted by *blackbelt* /forum/post/14638404
> 
> 
> Do you have to use oc 703? Or will any r-? insulation do? faceless or not?



Everything absorbs/reflects sound differently. Thickness and density makes a difference as well. Your questions do not lend themselves well to a yes or no answer because there are so many variables in play.


Here is a list of products that have been tested and their coefficients.
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## hdmi4ever

Those "Foam by Mail" people are really sad. Getting a shill to jump in here and shout how great their cheap foam is, in their one and only post on the whole forum.



> Quote:
> Originally Posted by *Bluewaterboy* /forum/post/12319447
> 
> 
> Well, I have been following this and other threads for a long time and have been reluctant to take the plunge because it seemed complicated to get it right and the cost was too much especially looking at off the shelf products. I liked the look of the studio foams like Sonex and Aurelex but the cost to treat my room was approximately $800. I saw several comments on here that the cheap foam does not work, B.S. I bought foam from the foam factory on e-bay and installed 8 bass traps in (2) 8 ft columns in the front of the theater and 54 1 foot sq. 3" wedges at all of the FRP's and the results were dramatic. The sound improved so much that my 7 year old and my wife both described the sound improvement much the way I heard it. I am extremely happy and all for $140 delivered to my door. Thanks for all of the info I guess all I am trying to say is it is not as complicated as it may seem.
> 
> 
> Rich


----------



## pepar




> Quote:
> Originally Posted by *blackbelt* /forum/post/14638404
> 
> 
> Do you have to use oc 703? Or will any r-? insulation do? faceless or not?



It's not the "R". Check 703's absorption coefficients here and then compare to whatever else you are considering. Some go more dense than 703. I don't recall anyone going less dense. Faced sheets are listed as well.


----------



## stepyourgameup

wierd how john mansville whispertone is 6pcf has less absorbtion in the 125hz range as the IS Black which is only 1.5pcf.

Attachment 119530


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14639996
> 
> 
> wierd how john mansville whispertone is 6pcf has less absorbtion in the 125hz range as the IS Black which is only 1.5pcf



At some point it becomes too dense.


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14640493
> 
> 
> At some point it becomes too dense.



Could you elaborate? That seems strange to me. Are you saying that it starts to reflect the sound wave instead of absorbing it?


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14640653
> 
> 
> Could you elaborate? That seems strange to me. Are you saying that it starts to reflect the sound wave instead of absorbing it?



Well, if it doesn't absorb it, then it either transmits it or reflects it. If the flat panel is mounted on a wall and it transmits sound through to the wall, the wall will either absorb it, transmit it or reflect it, probably some of each. The transmitted sound is heard in the adjacent room and the reflected sound goes back through the panel and back into the room.


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14642871
> 
> 
> Well, if it doesn't absorb it, then it either transmits it or reflects it. If the flat panel is mounted on a wall and it transmits sound through to the wall, the wall will either absorb it, transmit it or reflect it, probably some of each. The transmitted sound is heard in the adjacent room and the reflected sound goes back through the panel and back into the room.



Some people are making super chunk corner traps with OC703/705. If their wedges are 17x17x24, then the thickest part of the trap in the middle is 12". If you say that at some point the OC becomes too dense, then these super chunks are a bad idea?


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14643012
> 
> 
> Some people are making super chunk corner traps with OC703/705. If their wedges are 17x17x24, then the thickest part of the trap in the middle is 12". If you say that at some point the OC becomes too dense, then these super chunks are a bad idea?



No, they are a great idea and more effective than most commercial traps. At some point, the _fiberglass_ is too dense and will not be as effective at absorbing. Neither 703 or 705 fall into that category for chunk traps though. Bob Gold's chart is not for chunk traps. In the StudioTips Forum on SSC traps there is comparison data on sheets straddling the corner and the chunk style.


----------



## blackbelt

Thanks for the links and info. All.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14643012
> 
> 
> Some people are making super chunk corner traps with OC703/705. If their wedges are 17x17x24, then the thickest part of the trap in the middle is 12". If you say that at some point the OC becomes too dense, then these super chunks are a bad idea?



Density is not the same thing as thickness.


----------



## stepyourgameup




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/14643637
> 
> 
> Density is not the same thing as thickness.



I knew that, stupid of me.


BTW, one of my corners is next to a door. I only have 12" from the wall to the door so a normal piece of 2'x4' will be too big. Will it hurt too much to make the trap smaller so that it doesn't interfere with the door or should I just live with it?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14643704
> 
> 
> BTW, one of my corners is next to a door. I only have 12" from the wall to the door so a normal piece of 2'x4' will be too big. Will it hurt too much to make the trap smaller so that it doesn't interfere with the door or should I just live with it?



Depends on which way the door opens.


----------



## stepyourgameup




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/14643812
> 
> 
> Depends on which way the door opens.



The door will open just fine as it opens to the back bedroom. So would making the trap smaller hurt its effectivness too much?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14645409
> 
> 
> The door will open just fine as it opens to the back bedroom. So would making the trap smaller hurt its effectivness too much?



I meant: Does it open in or out. In any case, if it is a superchunk, I would not make it smaller since the depth is the most important parameter for the bass. I would cut the protruding corner at the door, if absolutely necessary.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14645409
> 
> 
> The door will open just fine as it opens to the back bedroom. So would making the trap smaller hurt its effectivness too much?



It's probably better to put a trap there even if it is not the full profile (within reason) than to not have one there at all. Post a sketch of the full triangle w/dimensions and then show the reduction for the door.


Also, wall-to-wall corners are not the only corners in your room . . .


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/14643309
> 
> 
> In the StudioTips Forum on SSC traps there is comparison data on sheets straddling the corner and the chunk style.



Do you happen to have a link?


Thanks,

CJ


----------



## pepar

 http://forum.studiotips.com/viewtopic.php?f=8&t=536


----------



## CJO

Thanks!


CJ


----------



## Lonely Raven

Have there been any tests or studies on the difference in absorbtion at LF with a Super Chunk pressed up to the wall vs leaving say a 1" or 2" space between the chunk and the wall?


Has anyone compared a solid LF absorber like the Decware C.W.A.L. (I think that's the name for the Decware bass trap) vs a Super Chunk?


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14650493
> 
> 
> Have there been any tests or studies on the difference in absorbtion at LF with a Super Chunk pressed up to the wall vs leaving say a 1" or 2" space between the chunk and the wall?
> 
> 
> Has anyone compared a solid LF absorber like the Decware C.W.A.L. (I think that's the name for the Decware bass trap) vs a Super Chunk?



The only comparisons that have been done are the ones at the link. Being a DIY product with no company making any money on them, there is no commercial backing for testing. In fact, I imagine that no commercial trap maker wants their products going anywhere near a test against SSC traps.


----------



## stepyourgameup

Here is what I bought. This is all I could find local. How does 4" corner traps, not super chunks, and 1" wall panels look?

Attachment 119586 


looks like 100% absorption at 1000hz.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14651486
> 
> 
> Here is what I bought. This is all I could find local. How does 4" corner traps, not super chunks, and 1" wall panels look?
> 
> Attachment 119586
> 
> 
> looks like 100% absorption at 1000hz.



Lower would be better.


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14652508
> 
> 
> Lower would be better.



So I should go 2"? 100% absorption at 250hz.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14652880
> 
> 
> So I should go 2"? 100% absorption at 250hz.



Yes, much better. What traps? 4" panel(s) straddling the corners?


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14653341
> 
> 
> Yes, much better. What traps? 4" panel(s) straddling the corners?



Yes. I think the superchunks are gonna cost too much.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14653637
> 
> 
> Yes. I think the superchunks are gonna cost too much.



Understood. That type works quite well and is much less $$$ than filling the triangle. Just make sure that the edges of the panels touch the walls.


----------



## Lonely Raven




> Quote:
> Originally Posted by *pepar* /forum/post/14650603
> 
> 
> The only comparisons that have been done are the ones at the link. Being a DIY product with no company making any money on them, there is no commercial backing for testing. In fact, I imagine that no commercial trap maker wants their products going anywhere near a test against SSC traps.



I have heard that before (about going up against the SC).


Well, I have two of the Decware bass trapes. They are only 6' tall, so it wouldn't be fair to test against a floor to ceiling Chunk...but once my speakers show up and I can start doing some testing, I'll see what happens with two Decware traps vs two Chunks of equal size.


What interests me is that the Decware bass trap is solid, and the build directions state that alternating acoustic insulation with air (in the case 1" bubble wrap) causes it to reach deeper than just acoustic insulation.


Just food for though. I have no idea if this is true or not, and my theater setup isn't going to be ideal for testing...


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14656175
> 
> 
> I have two of the Decware bass trapes. They are only 6' tall, so it wouldn't be fair to test against a floor to ceiling Chunk...but once my speakers show up and I can start doing some testing, I'll see what happens with two Decware traps vs two Chunks of equal size.
> 
> 
> What interests me is that the Decware bass trap is solid, and the build directions state that alternating acoustic insulation with air (in the case 1" bubble wrap) causes it to reach deeper than just acoustic insulation.
> 
> 
> Just food for though. I have no idea if this is true or not, and my theater setup isn't going to be ideal for testing...



Do you have a link? I am on the Decware website and the only acoustical treatments I can find are diffusors.


----------



## SteveMo

Does anyone else have DIY Helmholtz Resonators? Is anyone interested in seeing results of a couple of them? I'm about to fill some with insulation.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *SteveMo* /forum/post/14657064
> 
> 
> Does anyone else have DIY Helmholtz Resonators? Is anyone interested in seeing results of a couple of them? I'm about to fill some with insulation.




Uhmmm........ this is an acoustical treatment thread.... of course we're interested.







Yes, please post your results.


----------



## SteveMo

Will do then.


----------



## SteveMo

The audience is growing impatient so not much time to go into details at this time. There are two 12" woofers in the left front corner and two 12" woofers in the back right corner.


This is a measurement from yeterday night I did at the same location. I did not calibrate the SPL but turns out to be a 75dB target with speakers small, 80dB large on my XA2 with DVE. No equalization with all of these.











Animation of opening a Helmhotz Resonator and filling with pink. The second was then opened and filled. Then both access areas were sealed with plywood and the covering and couch went back for the final pic. Measurements were taken in the front row, but there is a larger difference in the back row. The bass in the room becomes more even in all areas.











End result with 80dB calibration.


----------



## elee532

I'm planning to build some superchunk corner bass traps. For aesthetic reasons (there is a ledge and some molding), I'm looking at having a 3" break in the trap about half way up the wall. Is this a problem for any reason? (FYI, I'm also planning some additional traps in one of the back corners and the front wall-ceiling corner.


Thanks.


----------



## Lonely Raven




> Quote:
> Originally Posted by *pepar* /forum/post/14656962
> 
> 
> Do you have a link? I am on the Decware website and the only acoustical treatments I can find are diffusors.



Looks like Decware no longer sells plans for the old style diffusers and absorbers. I happened to find my blueprints for them just the other day, so when I have time I'm going to review them a bit and see if I can glean any more information off them.


Doing a little Googling, I found this page:

http://www.decware.com/achowto.htm 


Which has a few photos of the diffusers and absorbers that look exactly as I built. The bass traps are the big coffin like devices. Basically imagine a corner trap 6' tall, completely enclosed, and filled with alternating layers of acoustic insulation and bubble wrap. The insulation recommended was Thermafiber (don't recall which model but I'll figure it out as I still have 10 sheets in storage).


The Decware stuff was my introduction to room treatment. The bass trap made a huge improvement to my little apartment living room theater. So they do *something*, but I'm wondering if they do as well as Super Chunks. So I'll do some testing as I get my setup together (hopefully later this week). I have my ECM8000, Mackie Mixer, Computer, and REW...I'm just waiting on speakers and I need to find my Rat Shack DB meter(and trying to learn the software).


----------



## Lonely Raven

I just found this old photo of my living room of the apartment I used to have. You can see some of the MDF bass trap in the corner, plus all my diffusers piled up on one wall behind the guitar amps. I sorta gave up the living room to aquariums so I just packed everything up till we got a house just recently.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14658581
> 
> 
> I'm planning to build some superchunk corner bass traps. For aesthetic reasons (there is a ledge and some molding), I'm looking at having a 3" break in the trap about half way up the wall. Is this a problem for any reason?



That won't be a problem. But maybe you could devise a way to not have the gap by running the trap continuously. Your edge trim would need to follow the irregularity of the ledge but, aesthetically, the continuous trap may be better.


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14659296
> 
> 
> Looks like Decware no longer sells plans for the old style diffusers and absorbers. I happened to find my blueprints for them just the other day, so when I have time I'm going to review them a bit and see if I can glean any more information off them.
> 
> 
> Which has a few photos of the diffusers and absorbers that look exactly as I built. The bass traps are the big coffin like devices. Basically imagine a corner trap 6' tall, completely enclosed, and filled with alternating layers of acoustic insulation and bubble wrap. The insulation recommended was Thermafiber (don't recall which model but I'll figure it out as I still have 10 sheets in storage).
> 
> 
> The Decware stuff was my introduction to room treatment. The bass trap made a huge improvement to my little apartment living room theater. So they do *something*, but I'm wondering if they do as well as Super Chunks. So I'll do some testing as I get my setup together (hopefully later this week). I have my ECM8000, Mackie Mixer, Computer, and REW...I'm just waiting on speakers and I need to find my Rat Shack DB meter(and trying to learn the software).



The corner traps look very similar to SSC traps except that they are movable and, as you pointed out, do not go from floor to ceiling. No way to know their performance compared to SSC traps without a comparison under the same test conditions. Have you ever see _any_ test data?


The advantage that I see with a movable trap is that it is . . . movable. But the downside is that it cannot be integrated into the room structure. And with most rooms having base 1/2" - 3/4" thick base molding, it will have that gap between it and the wall. I mention that only as an aesthetic concern of mine, not performance. And that "sitting there" look is my objection to all commercially available traps.


Just my $.02.


----------



## AnthemAVM

Hello everyone.


I want to build some superchunks corner traps. I want them to be portable. Is there any plans of how to make them.


I am thinking of traingle end caps, then some 2x1 wood strips. Anyone have any good plans?


Thanks


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14660475
> 
> 
> That won't be a problem. But maybe you could devise a way to not have the gap by running the trap continuously. Your edge trim would need to follow the irregularity of the ledge but, aesthetically, the continuous trap may be better.



Thanks Pepar. I am planning to put some curtains on the top half of the wall that would hang down to the ledge (this would be partly to cover a window and partly for pure aesthetic reasons). Given this, I was thinking it would look odd for the traps to come out from under the drapes. However, I'm willing to give up a little bit of aesthetics if there is a good acoustic reason to do so.


Thanks for any thoughts.


----------



## pepar




> Quote:
> Originally Posted by *AnthemAVM* /forum/post/14661205
> 
> 
> Hello everyone.
> 
> 
> I want to build some superchunks corner traps. I want them to be portable. Is there any plans of how to make them.
> 
> 
> I am thinking of traingle end caps, then some 2x1 wood strips. Anyone have any good plans?



You'll be the first! All of the implementations of the SSC traps that I have seen have been "built in."


----------



## amirm

Ran into the nice folks at A/V RoomService at CEDIA. Looking on their web site, I found these nice set of links, showing a comparison of studio recording and then in treated and untreated room. Worth a quick listen for folks not knowing what they are solving for with traps and such







.

http://www.avroomservice.com/sounds/


----------



## eugovector




> Quote:
> Originally Posted by *amirm* /forum/post/14662110
> 
> 
> Ran into the nice folks at A/V RoomService at CEDIA. Looking on their web site, I found these nice set of links, showing a comparison of studio recording and then in treated and untreated room. Worth a quick listen for folks not knowing what they are solving for with traps and such
> 
> 
> 
> 
> 
> 
> 
> .
> 
> http://www.avroomservice.com/sounds/



Interesting, but from reading their descriptions, it seems that the rooms, in addition to having different acoustic treatment, may also have different construction, dimensions, etc. Would be more interesting if it were the same room with the treatments covered/removed.


----------



## pepar




> Quote:
> Originally Posted by *amirm* /forum/post/14662110
> 
> 
> Ran into the nice folks at A/V RoomService at CEDIA. Looking on their web site, I found these nice set of links, showing a comparison of studio recording and then in treated and untreated room. Worth a quick listen for folks not knowing what they are solving for with traps and such
> 
> 
> 
> 
> 
> 
> 
> .



Educating the consumer. What an insidious way for them to sell more products.


----------



## Lonely Raven

Pepar, Agreed on the aesthetics of the CWAL. And the directions did say that 1/2" gap improves performance. I'm just curious of being in a sealed box enhances the low frequency absorption. If it does, then I might just have to make an enclosed floor to ceiling version...imagine a super chunk inside one of these.


As for measurements...I did see some measurements back in the day, but they weren't published exactly. Just something shown to me while I was visiting their listening room.


elee, I did see someone made a portable super chunk. He did like you are imagining with a triangle top and bottom, held together with what looked like 1/2" dowel at the three corners, then wrapped in fabric. It looked like it was 4' tall so it would take two of them stacked to fill a corner.


That exact method was going to be my plan as well. I figured I'd use dowels drilled through the base and top piece, glued in for stability. Then I'd just trim out the corners of the insulation so it doesn't bunch up and show through the fabric. My ceilings are exactly 8', so I'm going to lose a couple inches making two of these to stack. Not a big deal I figure...but I want to be able to measure before and after and compare the super chunks to the CWAL and see how well they work.


Hell, if the CWAL holds it's own in the double digit frequency, I may just use a combo of CWAL with portable Super Chunk stacked. But I'm guessing that's asking too much of a bass absorber to reach down so low without being tuned specifically for a double digit freq.


----------



## amirm




> Quote:
> Originally Posted by *eugovector* /forum/post/14664048
> 
> 
> Interesting, but from reading their descriptions, it seems that the rooms, in addition to having different acoustic treatment, may also have different construction, dimensions, etc. Would be more interesting if it were the same room with the treatments covered/removed.



I didn't read it as much as advertisement for their services but rather, what the difference is between the source and and a room with lots of reverbrations. And then ponder if the "treated" room is the sound folks would like better.


Agree that the more before and after tests, the better.


----------



## elee532

Lonely Raven, FYI, you directed your response above to me but I but it was actually AnthemAVM who asked about building portable super chunks.


My question was whether there was any major acoustic drawback to having a 3" break half-way up the wall in a corner superchunk?


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14670306
> 
> 
> Lonely Raven, FYI, you directed your response above to me but I but it was actually AnthemAVM who asked about building portable super chunks.
> 
> 
> My question was whether there was any major acoustic drawback to having a 3" break half-way up the wall in a corner superchunk?



No performance "drawback."


----------



## Dennis Erskine

See Floyd Toole's new book, Sound Reproduction. Available on Amazon.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14671866
> 
> 
> See Floyd Toole's new book, Sound Reproduction. Available on Amazon.



Thanks, headed to Amazon right now.


And am picking up T. Holman's as well.


- Jeff


----------



## cavchameleon




> Quote:
> Originally Posted by *pepar* /forum/post/14672153
> 
> 
> Thanks, headed to Amazon right now.
> 
> 
> And am picking up T. Holman's as well.
> 
> 
> - Jeff



Add me to that! I've read some of Floyd Toole's papers, great insite. I'm heading over to Amazon also.


Thanks!

Ray


----------



## AnthemAVM




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14665586
> 
> 
> Pepar, Agreed on the aesthetics of the CWAL. And the directions did say that 1/2" gap improves performance. I'm just curious of being in a sealed box enhances the low frequency absorption. If it does, then I might just have to make an enclosed floor to ceiling version...imagine a super chunk inside one of these.
> 
> 
> As for measurements...I did see some measurements back in the day, but they weren't published exactly. Just something shown to me while I was visiting their listening room.
> 
> 
> elee, I did see someone made a portable super chunk. He did like you are imagining with a triangle top and bottom, held together with what looked like 1/2" dowel at the three corners, then wrapped in fabric. It looked like it was 4' tall so it would take two of them stacked to fill a corner.
> 
> 
> That exact method was going to be my plan as well. I figured I'd use dowels drilled through the base and top piece, glued in for stability. Then I'd just trim out the corners of the insulation so it doesn't bunch up and show through the fabric. My ceilings are exactly 8', so I'm going to lose a couple inches making two of these to stack. Not a big deal I figure...but I want to be able to measure before and after and compare the super chunks to the CWAL and see how well they work.
> 
> 
> Hell, if the CWAL holds it's own in the double digit frequency, I may just use a combo of CWAL with portable Super Chunk stacked. But I'm guessing that's asking too much of a bass absorber to reach down so low without being tuned specifically for a double digit freq.



Thanks, didn't think of the dowels, I was thinking of using 1x2 strips at the corners, for a total of six.


Michael


----------



## BILLSID29

Can anyone tell me if this Duct board will work for my acoustic panels.

http://www.certainteed.com/NR/rdonly...ardSpecSht.pdf 


Thanks


----------



## stepyourgameup




> Quote:
> Originally Posted by *BILLSID29* /forum/post/14675075
> 
> 
> Can anyone tell me if this Duct board will work for my acoustic panels.
> 
> http://www.certainteed.com/NR/rdonly...ardSpecSht.pdf
> 
> 
> Thanks



It looks like your getting 100% absorption at 500hz at 2" thick and 77% at 1" thick. Should work good. I would definately do 2" though.


----------



## elee532

Two questions re: superchunck corner bass traps...


1. When building a superchunk corner bass trap (i'm using Roxul Rockboard 60), is it necessary for the triangle pieces to sit right up against the two walls or can there be a gap of 2" or 3" between the trap and the walls?


2. Is there a substantial difference between traps that are 24" x 17" x 17" and traps that are 34" x 24" x 24"? Both my floor space and budget are limited, so I'm really hoping to use the smaller triangles, but only if the tradeoff in absorption is minimal.


Thanks!


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14699737
> 
> 
> Two questions re: superchunck corner bass traps...
> 
> 
> 1. When building a superchunk corner bass trap (i'm using Roxul Rockboard 60), is it necessary for the triangle pieces to sit right up against the two walls or can there be a gap of 2" or 3" between the trap and the walls?
> 
> 
> 2. Is there a substantial difference between traps that are 24" x 17" x 17" and traps that are 34" x 24" x 24"? Both my floor space and budget are limited, so I'm really hoping to use the smaller triangles, but only if the tradeoff in absorption is minimal.



The 34's reach lower, but they are truly super-chunky and not everyone can tolerate them aesthetically. Consider the corner formed by the juncture at the wall and ceiling and install the 24" design there in addition to the wall-to-wall corners when you can.


With even one corner trapped you will be ahead of most home theaters.


----------



## elee532

Thanks Pepar. Any idea whether it matters if the trap actually touches the two walls, or can it sit out from the wall. I thought I read somehwere that there might be an problem with certain frequencies if there is a gap between the trap and the wall.


I am planning to do at least one wall-ceiling corner. I'm pretty sure this one will be hidden by a curtain, so the 34" x 24" x 24" design shouldn't be an issue.


Is there any value in a superchunk smaller than 24" x 17" x 17"? There is a corner formed about 2/3 of the way toward the back of my room where the ceiling drops down about 12". I was thinking about making a 17" x 12" x 12" trap to fill this corner. Is it worth it?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14704760
> 
> 
> Thanks Pepar. Any idea whether it matters if the trap actually touches the two walls, or can it sit out from the wall. I thought I read somehwere that there might be an problem with certain frequencies if there is a gap between the trap and the wall.



I don't know about that for the "solid" trap, but the corner absorber that is simply a 24" x 48" x 2" panel straddling the corner needs to be touching the walls. FWIW, I have never seen a DIY SSC trap that wasn't built tight in the corner. I have seen commercial corner traps that sit out from the walls because of the base molding. Those manufacturers, no doubt, will tell you that a gap is OK/better.











> Quote:
> Is there any value in a superchunk smaller than 24" x 17" x 17"? There is a corner formed about 2/3 of the way toward the back of my room where the ceiling drops down about 12". I was thinking about making a 17" x 12" x 12" trap to fill this corner. Is it worth it?



2/3 of the way back - is it a corner that is not one of the four room corners?


----------



## mike_wassell

I have several questions.


Can I use diffusion in a small HT 17’ x 13’ x 8’ when sitting less than 8’ from the walls?


I am thinking about putting absorption on approximately 35% of my walls and ceiling space (not counting the floor space). Is this a good number? I don’t want to make my HT too dead. I will put bass traps in the corners and absorption on the sidewalls and ceiling (reflection points) and behind the speakers. What should I do on the rear wall – leave it alone, diffusion or absorption? I was thinking of putting diffusion on the rear walls until I read that some references think that diffusion should not be used in small rooms.


I will be using Rockwool (because it is economical and I can get it locally) in lumber frames covered with an acoustically transparent fabric. I will be using 1” x 4” lumber for the frames w/2” thick Rockwool except for the bass traps. I will mount the frames flat against the wall which will give me a 1.5” air gap behind the Rockwool (the room is small and I don’t have much room for air gaps). Do I need to put a back (fabric) on the rock wool? I was thinking that I would not need to put a back on the Rockwool since the frame is flat against the wall and I do not plan on disturbing the Rockwool. I will hold the Rockwool in place with small wood blocks screwed into the back of the frame. I will use 6" of Rockwool mounted in the front corners for bass traps. I can't mount bass traps in rear due to doors.


I would be grateful for any other suggestion.


----------



## stepyourgameup




> Quote:
> Originally Posted by *mike_wassell* /forum/post/14712535
> 
> 
> I have several questions.
> 
> 
> Can I use diffusion in a small HT 17' x 13' x 8' when sitting less than 8' from the walls?
> 
> 
> I am thinking about putting absorption on approximately 35% of my walls and ceiling space (not counting the floor space). Is this a good number? I don't want to make my HT too dead. I will put bass traps in the corners and absorption on the sidewalls and ceiling (reflection points) and behind the speakers. What should I do on the rear wall - leave it alone, diffusion or absorption? I was thinking of putting diffusion on the rear walls until I read that some references think that diffusion should not be used in small rooms.
> 
> 
> I will be using Rockwool (because it is economical and I can get it locally) in lumber frames covered with an acoustically transparent fabric. I will be using 1 x 4 lumber for the frames w/2 thick Rockwool except for the bass traps. I will mount the frames flat against the wall which will give me a 1.5 air gap behind the Rockwool (the room is small and I don't have much room for air gaps). Do I need to put a back (fabric) on the rock wool? I was thinking that I would not need to put a back on the Rockwool since the frame is flat against the wall and I do not plan on disturbing the Rockwool. I will hold the Rockwool in place with small wood blocks screwed into the back of the frame. I will use 6" of Rockwool mounted in the front corners for bass traps. I can't mount bass traps in rear due to doors.
> 
> 
> I would be grateful for any other suggestion.



If your using 6" for bass traps in the corner, you can use the same amount of material and make 4' tall superchunk bass traps. Assuming the rockwool is 2'x4'.


----------



## BILLSID29




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14675272
> 
> 
> It looks like your getting 100% absorption at 500hz at 2" thick and 77% at 1" thick. Should work good. I would definately do 2" though.



Step,

Thanks for the response, I'll use the 2"!


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14707832
> 
> 
> 2/3 of the way back - is it a corner that is not one of the four room corners?



I included a photo below of the back of the room. As you can see, the ceiling drops down 12 inches and forms a corner. This is the area that I was thinking about filling with some 17" x 12" x 12" Rockboard triangles. Will it have any effect?


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14717319
> 
> 
> I included a photo below of the back of the room. As you can see, the ceiling drops down 12 inches and forms a corner. This is the area that I was thinking about filling with some 17" x 12" x 12" Rockboard triangles. Will it have any effect?



I'm sure it would have some effect. Don't know how much though. FWIW, I'd do it if it were my room for aesthetics - to soften it visually. And I'd take whatever absorption I got in the process.


Just my $.02.


----------



## byte02553

I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.


Wayne


----------



## stepyourgameup

Here is some pics of the end of day 1 building my superchunk bass traps. I have a question, as you can see the right has a door there. When I stick my head in that corner, the bass is practically nill. Probably has something to do with the door. Should I even worry about treating that corner? It seems like an LFE black hole.

Attachment 120484 

Attachment 120485 

Attachment 120486


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14723410
> 
> 
> Here is some pics of the end of day 1 building my superchunk bass traps. I have a question, as you can see the right has a door there. When I stick my head in that corner, the bass is practically nill. Probably has something to do with the door. Should I even worry about treating that corner? It seems like an LFE black hole.



It's where LFE goes to die?










Did you listen with the door closed and before stacking fiberglass? Did you listen to the other corners?


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14723455
> 
> 
> It's where LFE goes to die?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Did you listen with the door closed and before stacking fiberglass? Did you listen to the other corners?



door closed, before stacking fiberglass. The corner that is getting the chunks definately had strong bass. The back right corner sounds good and the back left corner is facing the stairs going up. The front right corner also has a return air vent going into the a/c.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14723684
> 
> 
> door closed, before stacking fiberglass. The corner that is getting the chunks definately had strong bass. The back right corner sounds good and the back left corner is facing the stairs going up. The front right corner also has a return air vent going into the a/c.



I guess room layout, doors and such could be the reason. You could place a stack there - loose - and see if it makes any audible difference. Being a corner, in spite of your observation, it has to help.


----------



## Lonely Raven

Interesting.


Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?


Just throwing this idea out there...if there is a null in a corner, that just proves that there is as much bass (if not more?) since it takes both positive and negative waves to make a null. So maybe it's *more* important to treat that null than it is to treat the loud corner?


Just thinking out loud. Especially since I have an L shaped room with open doorways, and I'm not sure which corners are going to be the important ones that *have* to be treated. I'm not sure I have the option to treat them all (both budget wise and aesthetically).


At this point, I'm thinking about throwing some money at one of the gurus here just to point me in the right direction. Something I recommend anyone do who can't measure a room (or in my case doesn't understand the measurements! LOL)


----------



## stepyourgameup




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14728350
> 
> 
> Interesting.
> 
> 
> Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?
> 
> 
> Just throwing this idea out there...if there is a null in a corner, that just proves that there is as much bass (if not more?) since it takes both positive and negative waves to make a null. So maybe it's *more* important to treat that null than it is to treat the loud corner?
> 
> 
> Just thinking out loud. Especially since I have an L shaped room with open doorways, and I'm not sure which corners are going to be the important ones that *have* to be treated. I'm not sure I have the option to treat them all (both budget wise and aesthetically).
> 
> 
> At this point, I'm thinking about throwing some money at one of the gurus here just to point me in the right direction. Something I recommend anyone do who can't measure a room (or in my case doesn't understand the measurements! LOL)



From my understanding, room treatments will not improve a null. Room treatments are there to help reduce boominess so the bass sounds tighter. So if you stick your head in a corner and the bass sounds louder or "boomier" then you need treatments. Nulls can only be eliminated by moving the sub or adding another sub.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14728350
> 
> 
> Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?



Yes, bass traps work best where bass builds up. Then they have something to act on. More on that here:

Pink noise aids placing bass traps 


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14728852
> 
> 
> From my understanding, room treatments will not improve a null.



This is not correct. Bass traps reduce peaks, raise nulls, and reduce decay time.


--Ethan


----------



## Kal Rubinson




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14728852
> 
> 
> From my understanding, room treatments will not improve a null.



Nope. Nulls and peaks are caused by the same thing (interactions of reflected energy) with the peaks being additive (in phase) and the nulls being subtractive (out of phase). So, if one reduces the peaks by reducing the room's ability to sustain energy at that frequency, one also reduces the nulls at that frequency as a concomitant.


BTW, moving a sub or other source can have an ameliorating effect but, since it does not change the basic acoustics of the room, peaks/nulls will remain. It's just that the sub and/or the listener will not be in the same place.


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14728350
> 
> 
> Interesting.
> 
> 
> Would you say that sticking your head in a corner and audibly sampling the bass would help you choose a corner if you could only treat one or two corners?
> 
> 
> Just throwing this idea out there...if there is a null in a corner, that just proves that there is as much bass (if not more?) since it takes both positive and negative waves to make a null. So maybe it's *more* important to treat that null than it is to treat the loud corner?
> 
> 
> Just thinking out loud. Especially since I have an L shaped room with open doorways, and I'm not sure which corners are going to be the important ones that *have* to be treated. I'm not sure I have the option to treat them all (both budget wise and aesthetically).



Well, room resonances are at "zero" at a boundary (wall) and all room resonances are present in corners, so not hearing a boom in a corner, now that I think about it, would be expected. Depending on the frequency/wavelength, a distance from a wall is where the boom (or null) would occur. If you have a square/rectangular room without any openings or irregularities, I think a corner is a corner and choosing wouldn't matter acoustically which ones were treated. It might aesthetically though.



> Quote:
> At this point, I'm thinking about throwing some money at one of the gurus here just to point me in the right direction. Something I recommend anyone do who can't measure a room (or in my case doesn't understand the measurements! LOL)



That is an excellent idea!


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14728948
> 
> 
> Yes, bass traps work best where bass builds up. Then they have something to act on. More on that here:
> 
> Pink noise aids placing bass traps
> 
> 
> --Ethan



I understand the metaphor, but it isn't correct, is it, that bass "builds up" in corners? There isn't more of it there than anywhere else, is it?


----------



## stepyourgameup




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14728965
> 
> 
> This is not correct. Bass traps reduce peaks, raise nulls, and reduce decay time.
> 
> 
> --Ethan



BruceK at Hometheatershack.com seems to disagree somewhat. He said that you would need a massive bass trap to improve a null, but it would be too big to get it into the room.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14729160
> 
> 
> BruceK at Hometheatershack.com seems to disagree somewhat. He said that you would need a massive bass trap to improve a null, but it would be too big to get it into the room.



I am with Ethan on this one. Bass traps reduce bass energy. Reducing bass energy reduces the magnitude of the waves bouncing around the room and the amount of interference, with "interference" being a frequency going in one direction meeting it's reflection traveling in, more or less, the opposite direction. Where both of those are at the top (or bottom) of their sine wave and out of phase, they cancel producing a null. Where both of them are at top (or bottom) of their sine wave and in phase, they add producing a boom. The null is destructive interference and the peak is constructive interference. If the waves meet and they are at zero, there is no peak or boom. They are ALL at zero at the boundaries, which is why there should be no boom (or null) in a corner.


Trapping bass smooths out both peaks and nulls equally. Don't know what BruceK is thinking.


----------



## Lonely Raven

Thanks for clearing those points up, Ethan and Kal.


I'm going to be working on trying to understand REW and my "L shaped" room acoustics better...and if I come up more confused than going into this, I'll probably be hiring someone to at least make suggestions for me.


This was much easier when I had an 11' X 16' room in my apartment! Blah!


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14729235
> 
> 
> I am with Ethan on this one. Bass traps reduce bass energy. Reducing bass energy reduces the magnitude of the waves bouncing around the room and the amount of interference, with "interference" being a frequency going in one direction meeting it's reflection traveling in, more or less, the opposite direction. Where both of those are at the top (or bottom) of their sine wave and out of phase, they cancel producing a null. Where both of them are at top (or bottom) of their sine wave and in phase, they add producing a boom.
> 
> 
> Trapping bass smooths out both peaks and nulls.



I have a null at around 70hz so I will take another measurement tonight with my new superchunk corner trap and see if it helped any. I also have some peaks at 25hz and another at 40hz.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14729296
> 
> 
> I have a null at around 70hz so I will take another measurement tonight with my new superchunk corner trap and see if it helped any. I also have some peaks at 25hz and another at 40hz.



Please report your observations.


----------



## krasmuzik




> Quote:
> Originally Posted by *pepar* /forum/post/14729235
> 
> 
> They are ALL at zero at the boundaries, which is why there should be no boom (or null) in a corner.



You got this wrong again - velocity is zero at a boundary - pressure (what you hear) is at a max at the boundary - which is why it is the best place to hear all the modal booms. In fact for the fundamental mode it is the only place - only the higher modes have pressure peaks within the room. The only place to not hear a null at any frequency will be in fact - the boundary (though there may be response dips between modal frequencies)


It is indeed correct that a pure velocity trap would be so large to be unuseable if you tried to reach the pressure nulls (velocity max) within the room. So any bass trap that works in corners is not trapping maximum velocity - as that is physically impossible. But that does not mean some can say they do not work - they may instead be trapping just some of the velocity or even be a pressure trap or even converting pressure to velocity.


----------



## pepar




> Quote:
> Originally Posted by *krasmuzik* /forum/post/14730128
> 
> 
> You got this wrong again - velocity is zero at a boundary - pressure (what you hear) is at a max at the boundary - which is why it is the best place to hear all the modal boom. In fact for the fundamental mode it is the only place - only the higher modes have pressure peaks within the room.



Thanks . . again. So, from where this all sprung, sticking one's head in a corner and not hearing any boom means a trap wouldn't have anything to trap there?


----------



## krasmuzik

It just means that corner does not have that modal frequency. It is entirely possible that a rectangular room coupled to another rectangular room has different corners with different modal response - you cannot predict these rooms using simple spreadsheet calculations.


----------



## SteveMo

90% of where I put treatments in my HT is based on where I feel pressure, the other 10% is measurements.


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/14730355
> 
> 
> 90% of where I put treatments in my HT is based on where I feel pressure, the other 10% is measurements.



Are you running a sweep or listening to music/movie?


----------



## SteveMo

I currently play sine waves -30dB FS, and watch movies while sitting in places one would not normally watch movies, such as standing on chairs or sitting in the front of my room next to my stage. The less difference it makes the more difficult it becomes. It is really really difficult to improve my room now. I started my treatments with a DIY subwoofer in a room with no framing. I then got a newer subwoofer after drywall went up and some few treatments such as the Helmholtz Resonator etc.. and started with loud rave music and walking around feeling the drywall move. It moved in the corners about 2ft away so I based my traps on that. I was carefull not to make the traps absorb an area that I heard while standing in a corner. A lower frequency ringing actually sounds quite similar to waking to an alarm clock before you awake. If adding Quiet Batt does nothing to improve my right corner and if it makes my 55Hz null worse again as it did with insulation I will be putting nothing there, because as far as I am concerned my left and right side of the room sound and feel the same. Coincedently my back left corner is very similar. Now I am basing the treatments based on where removing my tile ceiling improves.. I was always tought subwoofer measurements cannot be trusted. I am finding that there is really no telling where a bass ringing in the room may be, because although it shows on my measurements on the right side of my front row seats, I only hear it standing in the front of my room. If anyone was to use the program I wrote to delay REW measurements until sitting in the seat, they would probobly find that they themselves absorb a null, or cause a peak. Now getting that to work in multiple locations that is something different.


----------



## stepyourgameup

I will probably go ahead and treat both front corners with superchunks anyway cause it can't hurt right?


Last night I was playing some games and listening to music with my left superchunk in place and I could definately tell an audible difference. The left front speaker was placed directly in front of the chunk and sounded much cleaner and crisper. I'm also sure that it helped my subwoofer although I am not an audiophile so I couldn't say how much.


Would you guys say that corner bass traps is essential in practically every home theater with a basic rectangular room?


----------



## SteveMo




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14730889
> 
> 
> I will probably go ahead and treat both front corners with superchunks anyway cause it can't hurt right?
> 
> 
> Last night I was playing some games and listening to music with my left superchunk in place and I could definately tell an audible difference. The left front speaker was placed directly in front of the chunk and sounded much cleaner and crisper. I'm also sure that it helped my subwoofer although I am not an audiophile so I couldn't say how much.
> 
> 
> Would you guys say that corner bass traps is essential in practically every home theater with a basic rectangular room?



Yes should be good. You would not be asking if not.


----------



## pepar




> Quote:
> Originally Posted by *stevemo* /forum/post/14730943
> 
> 
> yes should be good. You would not be asking if not.



+1


----------



## byte02553

Attaching Acoustic Panels to ceiling......


I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.


Wayne

____________________________________________________________ _

No takers....no one has any suggestions? Surely there must be something that someone has used to attach these light panels to the ceiling without hardware...


Wayne


----------



## elee532

Speaking of ceiling mounting, anyone know of any how-to's for mounting a superchunk trap in a ceiling-wall corner?


----------



## pepar




> Quote:
> Originally Posted by *byte02553* /forum/post/14735148
> 
> 
> Attaching Acoustic Panels to ceiling......
> 
> 
> I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.
> 
> 
> Wayne
> 
> ____________________________________________________________ _
> 
> No takers....no one has any suggestions? Surely there must be something that someone has used to attach these light panels to the ceiling without hardware...
> 
> 
> Wayne



I don't recall anyone attaching panels of any kind to a ceiling w/o fasteners. Small angle brackets are usually used and they can be painted to blend in with the ceiling. But I see your dilemma with not having a frame.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/14729055
> 
> 
> I understand the metaphor, but it isn't correct, is it, that bass "builds up" in corners? There isn't more of it there than anywhere else, is it?



There certainly is more bass in the corners. This is very easy to measure. Use REW and measure the response at the listening position and then again in a corner. Or just play THIS bassy pink noise and move an SPL meter around.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14729160
> 
> 
> BruceK at Hometheatershack.com seems to disagree somewhat. He said that you would need a massive bass trap to improve a null, but it would be too big to get it into the room.



Well, of course it depends on the frequency of the null. But your friend is wrong and doesn't understand the science. There are before / after graphs all over my company's web site showing peaks _and_ nulls being improved with bass traps. Below is a perfect example, with obvious improvements in nulls from about 50 Hz and higher.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/14730197
> 
> 
> So, from where this all sprung, sticking one's head in a corner and not hearing any boom means a trap wouldn't have anything to trap there?



Yes, but what you hear depends a lot on the key of the music and what frequencies it contains. This is why measuring using REW or equivalent is always better than by-ear just listening. Also, if you move your speakers, or buy new speakers, or add/change a subwoofer, that can affect what frequencies get to various places in a room. My approach is to treat all available corners if possible.


--Ethan


----------



## stepyourgameup




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14736314
> 
> 
> Well, of course it depends on the frequency of the null. But your friend is wrong and doesn't understand the science. There are before / after graphs all over my company's web site showing peaks _and_ nulls being improved with bass traps. Below is a perfect example, with obvious improvements in nulls from about 50 Hz and higher.
> 
> 
> --Ethan



That is good news for sure.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14736278
> 
> 
> There certainly is more bass in the corners.



And I have been disabused of the thinking that lead me to post what I did.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/0
> 
> 
> My approach is to treat all available corners if possible.
> 
> 
> --Ethan



Yes, and I am limiting myself to posting only that succinct and sage advice.


----------



## SteveMo

Mine was not a very conrtrolled test from where I started to where I am but you can see my first measurments, and where I am currently with bass trapping added bellow. The frst one has one sub on the back center wall, and the newer one is four of the same sub up front on the floor.


----------



## pepar

Thanks, SteveMo. Wonder what was happening on the "before" at around 120Hz?


----------



## SteveMo

The first one had a crossover engaged and was measured with the mains on, the second one does not have a crossover and the mains were off. I have no means to test with a crossover unless I use sound out of my XA2 DVD player and observe with an RTA. I'm guessing the 120Hz area with the ringing was related to the mains, and having not covered the first reflection points because it went away when I did that.


----------



## SteveMo

Here is ETC of my left and right mains before, and more recently a measurement on a single main, which was positioned pretty close to where I have it now. I will be investigating both more after I am done with the ceiling.


----------



## SteveMo




> Quote:
> Originally Posted by *SteveMo* /forum/post/13354712
> 
> 
> I recall someone recommending not to have back-panels on my ceiling tiles after I ordered them. I have tried removing those and it causes a slight null at around 160Hz, it smooths out my response from 100Hz to 60Hz and it increases the response from 10Hz to about 25Hz. This is after removing almost a complete row of them from the sides of my room.
> 
> 
> Should I continue to remove these?
> 
> 
> Above my tiles there isn't much. There is a layer of pink stuff I put across the ceiling joist I put up in a few hours. Above that is steel and concrete. Two steel beams run across the room horizontally and there is gaps between those. I need insulation for the back of my room and I was considering taking all the insulation out of my ceiling and placing those in my back wall area that is not filled with insulation. Then I could fill the ceiling with something else somehow. I was thinking maybe some Roxul but I am not sure how to place it. Any advise?



So I have almost finished the new install of these back panels with tape around the edges and half layers of OC R19 in them. Excellent for knocking creapie crawlies off the house, but now that I have removed most of the insulation from most of the ceiling coverage there is lots of bass up there, and most of the bass just all sounds like a big explosion. I narrowed down most of the problem to my front wall ceiling/wall corner, and my rear ceiling/wall corner. In the front of the room it almost sounds like someone slamming a door above me.










The ceiling here is 20' L X 13.5' W and between the tiles and the steel is 15.5" or 13.5". The closest distance from the joist and the steel is 7". On the left side of the room between the joist and the wall is 3.5" filled with insulation, on the right side it is 8.5", with heavy PVC I made into tiles and on the back wall it is currently lightly filled and with some tiles I made out of cork board 6.5". There are two steel support beams running from the left to right (filled spaces above where gaps were with the steel using pink) side, and a projector hush box with a 4" flexable duct and panny ceiling fan that I have insulation around.


Which would be best? I have found good results with GIK 244 traps up there for example. Pink insulation batts are difficult to install, and don't seem to work well for my application. The height to the ceiling tiles is 7' 6".


- 8 cases (X6) of 24 x 48 x 2 inch Roxul AFB 2.5 pcf (use two 2" layers)


- 2 orders of R-19 x 24 in. x 24 ft. Quiet Batt (5.5" thick)

- order more later because having nothing in an area is not good? Will not sound right?


- 4 cases (X6) of 24 x 48 x 2 inch Rockboard 60 - more later?


----------



## elee532

Can I use a microfiber material as the cover to my superchunk bass traps?


I bought these curtains to cover up a window and I was hoping I could also use them to cover the "grills" that I am making for my superchunk bass traps.


----------



## stepyourgameup

If you don't mind them reflecting higher frequencies then yes.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14761924
> 
> 
> Can I use a microfiber material as the cover to my superchunk bass traps?
> 
> 
> I bought these curtains to cover up a window and I was hoping I could also use them to cover the "grills" that I am making for my superchunk bass traps.



I would not use material in acoustical treatments for which the manufacturer made no claims regarding it's suitability for that purpose. And even then I'd want to see the test data. Can't address your wanting to cover the windows because I don't know what your goal is there.


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14762325
> 
> 
> I would not use material in acoustical treatments for which the manufacturer made no claims regarding it's suitability for that purpose. And even then I'd want to see the test data. Can't address your wanting to cover the windows because I don't know what your goal is there.



There is no way that material is going to reflect lower frequencies.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14762356
> 
> 
> There is no way that material is going to reflect lower frequencies.



That's true. And not in conflict with my position.


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14762613
> 
> 
> That's true. And not in conflict with my position.



So why do you care if he uses it on his superchunk?


----------



## Randy Ta

As you can see in the attached picture, I'm working on the acoustical treatment of my theater. I'm at this point due to the help you guys have give me so far & I appreciate it. Just finishing up on the super chunk install and will need to order a little more OC 703 for the front wall.


My question is for the first reflection points on the side walls and the ceiling, should I make 1" or 2" 703 panels? Also, how big should the panels be? The room is 16X 25 with 9' ceilings. On my rear wall I only have one corner that I can put super chunks in. Should I do it or leave both rear corners untreated?


Thanks for your help.


----------



## stepyourgameup




> Quote:
> Originally Posted by *Randy Ta* /forum/post/14763198
> 
> 
> As you can see in the attached picture, I'm working on the acoustical treatment of my theater. I'm at this point due to the help you guys have give me so far & I appreciate it. Just finishing up on the super chunk install and will need to order a little more OC 703 for the front wall.
> 
> 
> My question is for the first reflection points on the side walls and the ceiling, should I make 1" or 2" 703 panels? Also, how big should the panels be? The room is 16X 25 with 9' ceilings. On my rear wall I only have one corner that I can put super chunks in. Should I do it or leave both rear corners untreated?
> 
> 
> Thanks for your help.



2". The panels will be 2'x4'. In my HT, I will use 3 of these on each side for 2 rows of seats.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14763055
> 
> 
> So why do you care if he uses it on his superchunk?



Well, it it does in fact reflect higher frequencies, is that what is best for the overall acoustics of the room? If in the rear corner, would they create first reflection points bouncing sound at the listeners? Those would be my questions.


----------



## pepar




> Quote:
> Originally Posted by *Randy Ta* /forum/post/14763198
> 
> 
> As you can see in the attached picture, I'm working on the acoustical treatment of my theater. I'm at this point due to the help you guys have give me so far & I appreciate it. Just finishing up on the super chunk install and will need to order a little more OC 703 for the front wall.
> 
> 
> My question is for the first reflection points on the side walls and the ceiling, should I make 1" or 2" 703 panels? Also, how big should the panels be? The room is 16X 25 with 9' ceilings. On my rear wall I only have one corner that I can put super chunks in. Should I do it or leave both rear corners untreated?
> 
> 
> Thanks for your help.



Three corners are better than two. Have you considered the "corners" formed by the walls and ceiling?


----------



## Randy Ta




> Quote:
> Originally Posted by *pepar* /forum/post/14763367
> 
> 
> Three corners are better than two. Have you considered the "corners" formed by the walls and ceiling?



Pepar, I have not considered the rear wall where the wall meets the ceiling. Should that also have super chunks?


Regarding the front wall, I want to keep down the fiberglass dust and was thinking about covering the entire front wall with a black breathable fabric. Any problems there?


----------



## pepar




> Quote:
> Originally Posted by *Randy Ta* /forum/post/14763545
> 
> 
> Pepar, I have not considered the rear wall where the wall meets the ceiling. Should that also have super chunks?



It could. Your front wall/ceiling juncture has one. Whether or not it _should_ depends on your room's acoustics. But I have heard it said that you can't have too many bass traps. FWIW, I'm adding some to the rear of my room in addition to what I have behind my false wall.



> Quote:
> Regarding the front wall, I want to keep down the fiberglass dust and was thinking about covering the entire front wall with a black breathable fabric. Any problems there?



Nope. And if you are using an AT screen, you want the stuff behind it black or at least very dark.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14763351
> 
> 
> Well, it it does in fact reflect higher frequencies, is that what is best for the overall acoustics of the room? If in the rear corner, would they create first reflection points bouncing sound at the listeners? Those would be my questions.



I'm definitely concerned about my choice now.










I will have a superchunk in at least one rear corner of the room.


Also, I was thinking that I could hide the broadband absorption/diffusion panels that I might be getting behind these curtains.


I was really hoping to match my curtain fabric with my superchunk grills.


Is there any way to tell whether these curtains will reflect higher frequencies? They're pretty thin... when I hold them up, I can see light through them.


Thanks for any help!


----------



## stepyourgameup




> Quote:
> Originally Posted by *elee532* /forum/post/14763677
> 
> 
> I'm definitely concerned about my choice now.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I will have a superchunk in at least one rear corner of the room.
> 
> 
> Also, I was thinking that I could hide the broadband absorption/diffusion panels that I might be getting behind these curtains.
> 
> 
> I was really hoping to match my curtain fabric with my superchunk grills.
> 
> 
> Is there any way to tell whether these curtains will reflect higher frequencies? They're pretty thin... when I hold them up, I can see light through them.
> 
> 
> Thanks for any help!



Cover your mouth with it and see how easy it is to breath thru.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14763766
> 
> 
> Cover your mouth with it and see how easy it is to breath thru.



And remember to pull it away if you cannot breath.


----------



## elee532




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14763766
> 
> 
> Cover your mouth with it and see how easy it is to breath thru.



How easy should it be?


If I cover my mouth tight with the fabric and blow moderately, my breath does flow through the fabric.



> Quote:
> Originally Posted by *pepar* /forum/post/14765159
> 
> 
> And remember to pull it away if you cannot breath.



Good thing I read the rest of this thread before I tried!










Oh, and if anyone would be willing to offer their consulting services, I could easily mail you a small swatch of the fabric for a more informed opinion. Just PM me. Thanks!


----------



## ScruffyHT

OK ... I have tried to use sketchup to give a idea of what I am dealing with in trying to get some bass trapping in this room


sides at first reflection points will be oc703 or linacoustic


on the screen wall will be oc703 chunked in the corners ... speakers will sit in front of that with a audiotransparent enclosure ( did not draw that part )


the side soffits are filled with HVAC etc


but the back soffit is empty except for the projector


the notch out at the back in the soffit is the projector location ( did not turn out like it will in reality but you get the idea )


because of the doors at the back there is no good way to do any bass trapping down low so my question is ...


can I use the back soffit area for bass trapping ?


what I am thinking is to line it with MDF and fill with fiberglass and use audiotransparent material on either side of the projector location


good idea ? ... will it work ?


----------



## stepyourgameup




> Quote:
> Originally Posted by *elee532* /forum/post/14765589
> 
> 
> How easy should it be?
> 
> 
> If I cover my mouth tight with the fabric and blow moderately, my breath does flow through the fabric.
> 
> 
> 
> 
> Good thing I read the rest of this thread before I tried!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Oh, and if anyone would be willing to offer their consulting services, I could easily mail you a small swatch of the fabric for a more informed opinion. Just PM me. Thanks!



Well, you should be able to breathe better with it than you can with a 100% cotton shirt. Cotton is no good for higher freq.


----------



## elee532




> Quote:
> Originally Posted by *pepar* /forum/post/14763351
> 
> 
> Well, it it does in fact reflect higher frequencies, is that what is best for the overall acoustics of the room? If in the rear corner, would they create first reflection points bouncing sound at the listeners? Those would be my questions.



Pepar,


A few pages earlier in this thread you mentioned that it would be OK to put my acoustic treatments behind drapes because "the drapes are already absorbing the higher frequencies."


However, this most recent conversation has me understanding that the drapes will reflect the higher frequencies.


Can you clarify for me? My whole plan is based on putting my treatments (broadband and bass) behind these curtains. I even have my wife bought into the plan.










Thanks for your help!


----------



## RobZ

(I posted a specific thread with this but I may find more suggestions here)


I'm trying to improve on the acoustics in my open designed room (actually enclosed with curtain panels). I've covered the windows with heavy velvet drapes and light blocking shades (left side of room). I'm going to be ordering ATS Acoustics 24x48 4" thick panels to place behind the four window coverings. Should I opt for the open backed design or does the glass not reflect lower frequencies?


Also, I'm considering ordering two additional 24 x 48" 4" thick open backed panels (total of 8") to lay sideways against the wall behind the true sub (it's used for sub 60 Hz because there's an MBM-12 nearfield). Does this appear to be a good option for bass trapping? Will it actually be effective for sub 60 Hz frequency absorption?


Next to the sub (see pic, in the right front corner of the room) there is a cabinet in the corner. I was thinking it could be used as a bass trap by removing the door, covering it with a DIY grill cloth/frame, and stuffing it with fiberglass batting. Am I on the right track with this idea or am I missing something?


----------



## eugovector




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14765935
> 
> 
> Cotton is no good for higher freq.



Could you clarify this? Do you mean that cotton absorbs HF, or reflects it?


----------



## stepyourgameup




> Quote:
> Originally Posted by *eugovector* /forum/post/14768717
> 
> 
> Could you clarify this? Do you mean that cotton absorbs HF, or reflects it?



It reflects it. If you want to absorb high freq. then you need to use something highly breathable like burlap or muslin.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14766488
> 
> 
> Pepar,
> 
> 
> A few pages earlier in this thread you mentioned that it would be OK to put my acoustic treatments behind drapes because "the drapes are already absorbing the higher frequencies."
> 
> 
> However, this most recent conversation has me understanding that the drapes will reflect the higher frequencies.
> 
> 
> Can you clarify for me? My whole plan is based on putting my treatments (broadband and bass) behind these curtains. I even have my wife bought into the plan.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks for your help!



The truth is that unless test data exists for a particular fabric, I have no certainty on what it does. My sense is that most fabrics either absorb highs or pass them. In either case that fabric would be OK for broadband absorbers. But I think that there are also fabrics that could reflect them, which takes me back to wanting test data.


On the other hand, if the drapes are pleated and reflective, the highs will be diffused.










- Jeff


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14768796
> 
> 
> It reflects it. If you want to absorb high freq. then you need to use something highly breathable like burlap or muslin.



Got some test data on that?


----------



## Dennis Erskine




> Quote:
> Cotton is no good for higher freq.



This would not be correct. Nylon, polyester, burlap or otherwise makes no difference. The differences between each fabric is not based upon the material...it is based upon the weave and weight.


----------



## ScruffyHT

Any thoughts on post # 3930 ? - it may get lost & forgotten in this myriad of posts or should I make a seperate thread for it ? Thanks


----------



## budk

ScruffyHT - your best to make your own post for your question. My opinion of master threads or sticky threads is that they should be for general questions about common or best practices and materials and not for individual theater questions.


This thread would be 10% of it's size if we applied this criteria.... of course, it's just my opinion.


----------



## Weasel9992




> Quote:
> Originally Posted by *RobZ* /forum/post/14766629
> 
> 
> Also, I'm considering ordering two additional 24 x 48" 4" thick open backed panels (total of 8") to lay sideways against the wall behind the true sub (it's used for sub 60 Hz because there's an MBM-12 nearfield). Does this appear to be a good option for bass trapping? Will it actually be effective for sub 60 Hz frequency absorption?
> 
> 
> Down to 60Hz? Probably. Sub-60Hz? Not much using 4" panels. You'll get some gains there if you increase the panel thickness to 6".
> 
> 
> Next to the sub (see pic, in the right front corner of the room) there is a cabinet in the corner. I was thinking it could be used as a bass trap by removing the door, covering it with a DIY grill cloth/frame, and stuffing it with fiberglass batting. Am I on the right track with this idea or am I missing something?



That could work. It's a very small amount of surface area and volume so I'm not sure what kind of results you could expect, but in theory it should work.


Frank


----------



## pepar




> Quote:
> Originally Posted by *budk* /forum/post/14770062
> 
> 
> ScruffyHT - your best to make your own post for your question. My opinion of master threads or sticky threads is that they should be for general questions about common or best practices and materials and not for individual theater questions.
> 
> 
> This thread would be 10% of it's size if we applied this criteria.... of course, it's just my opinion.



People tend to post where they see activity. This thread stays active and therefore near the top.


----------



## Joe741

I've decided to try two GIK 244 bass traps in my cluttered (damn furniture ) living room and ran some LF pink noise through my system to see about good locations. LP1 and LP2 were both reading 75 db. The front right corner was reading 81 db while the left front corner was reading 85 db. The rear left corner was reading 77 db and the rear center was reading 76 db while no treatments can be made to the rear right corner.


From the above it seems the front corners are the locations in need of treatment. But... My TV is located in the left corner, I think a trap will fit behind the HDTV/stand with some breathing room but will it still be effective being boxed in?


----------



## stepyourgameup




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14769253
> 
> 
> This would not be correct. Nylon, polyester, burlap or otherwise makes no difference. The differences between each fabric is not based upon the material...it is based upon the weave and weight.



So why the hell did I buy all that burlap when I could have just used some nice fabric like cotton or polyester?


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14768828
> 
> 
> Got some test data on that?



I thought it was common knowledge. Otherwise why would I need to buy burlap as has been suggested many times on this forum?


----------



## ScruffyHT




> Quote:
> Originally Posted by *pepar* /forum/post/14770547
> 
> 
> People tend to post where they see activity. This thread stays active and therefore near the top.



OK then ... before I post another thread asking the same question is there any opinion on my post #3930 regarding bass traps in the soffit ?











Thanks


----------



## pepar




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/14774869
> 
> 
> OK then ... before I post another thread asking the same question is there any opinion on my post #3930 regarding bass traps in the soffit ?



Your drawing is confusing as well - unusual viewing angle, surfaces cut away. Sure, you could fill it with 703. I probably would not fill the entire width of the soffit, but keep it to the same width as the soffit around the rest of the room. For it to be effective though, the entire surface needs to be covered with AT material not just the "front."


----------



## krasmuzik




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14774858
> 
> 
> I thought it was common knowledge. Otherwise why would I need to buy burlap as has been suggested many times on this forum?



Burlap makes great firestarter for your campfire - that is why wood bags are usually burlap. People suggesting it are expensing their expendable life for a few bucks a yard.


The more commonly suggested Guilford Of Maine FR701 is a polyester with a very coarse open weave much like most burlap. More importantly it is named after the fire resistance standard which should be considered just as important for your use to have that rating. Even though it has a burlap look - it also has a much softer feel. I suspect that WAF on both issues outweigh any bucks saved - and it is one of the best performing for acoustical transparency fit for absorber and speaker covers - so there really is no WAF tradeoff (other than it looks like burlap - so they will want to spend more)


Most organic materials are inherently flammable unless retardant is added - but beware that humidity can "soak" out the retardant requiring annual reapplication. You will find most acoustical fabrics are indeed polyester because it just melts itself out. This same standard is used for drapes because they are the same application - a vertical hanging of fabric that can easily spread a fire.


Here is a random google hit on the topic....fire depts are the first to see the horrific results of flammable fabrics. Before you say my house never burnt down so I will save the bucks - ask yourself why do we have fire depts then?

http://www.ci.pasadena.ca.us/fire/Pr...blefabrics.asp 


While they recommend tight weaves over loose weaves for improved flammability ratings - but that is not good for acoustics as it will reflect high frequency. Since it is so hard to balance that fire/acoustics tradeoff - this is why it is best to just buy GOM FR701 - the desired open weave with a good flammability rating.


----------



## ScruffyHT




> Quote:
> Originally Posted by *pepar* /forum/post/14776322
> 
> 
> Your drawing is confusing as well - unusual viewing angle, surfaces cut away. Sure, you could fill it with 703. I probably would not fill the entire width of the soffit, but keep it to the same width as the soffit around the rest of the room. For it to be effective though, the entire surface needs to be covered with AT material not just the "front."



Is it difficult to see the soffit ? ... I rotated the sketchup so you could see the room layout as well as the soffit ... not sure I could make it open on both sides like you suggest and pass the WAF










the question is ... bass trapping is ideal in the corners right ? ... but since I have 2 doors at the back of the room will putting a bass trap in the soffit be effective or should I be looking at utilizing the riser as a supplemental bass trap instead ( back of riser will be 5 feet from rear wall ... dimensions are 12'x6'X16" ) ... is it possible for the riser to be used for bass trapping to compensate for rear corner traps ?


I am concerned that having bass traps in only the front corners will create problems in the back


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14774858
> 
> 
> I thought it was common knowledge. Otherwise why would I need to buy burlap as has been suggested many times on this forum?



Where did you read that you should use burlap?


----------



## pepar




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/14778272
> 
> 
> Is it difficult to see the soffit ? ... I rotated the sketchup so you could see the room layout as well as the soffit ... not sure I could make it open on both sides like you suggest and pass the WAF



Well, if the frequencies don't hit it, the trap will not absorb them.



> Quote:
> the question is ... bass trapping is ideal in the corners right ? ... but since I have 2 doors at the back of the room will putting a bass trap in the soffit be effective or should I be looking at utilizing the riser as a supplemental bass trap instead ( back of riser will be 5 feet from rear wall ... dimensions are 12'x6'X16" ) ... is it possible for the riser to be used for bass trapping to compensate for rear corner traps ?
> 
> 
> I am concerned that having bass traps in only the front corners will create problems in the back



To quote Ethan - or at least paraphrase him as I haven't bookmarked the page - bass hangs out in the corners, so that is the best place to, umm . . kill it.










Too bad your soffits contain HVAC ducts as that area would be perfect locations for traps. Do the corners that you can and you will be ahead of many people. One corner is better than none, two corners are better than one, etc.


----------



## ScruffyHT

Thanks ... is the use of the riser for bass trapping effective for helping out with the rear of the room since it is " close " to the back of the room and I am filling it with insulation anyway


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14779865
> 
> 
> Where did you read that you should use burlap?



It's all over this thread.


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14782883
> 
> 
> It's all over this thread.



I either missed it or, more likely, ignored it. I understand the resistance that some have to spending the money that GOM costs and that leads to members coming up with all sorts of bargain fabrics that they found at the hardware store or fabric shop. Some of them are real eye-rollers.










Expensive as it is, GOM is designed for use in acoustical applications. Any fabric that isn't is a pig in a poke.


Sorry, but that's just the way it is.


- Jeff


----------



## ScruffyHT

I know it has been said before but a FAQ would be cool ... "most" theatres here are rectangular with 4 walls and either have a AT screen ( so certain process to follow there ) or standard fixed or roll down screen


example


screen wall - corner traps ( and how to make them including insulation and material to cover it







) also what insulation to use on rest of the screen wall


side walls - first reflection points ( link to first reflection program or description of mirror test )


rear wall - corner traps ... also maybe treated for reflections


ceiling/floor - first reflections


Risers as bass traps ( my current question














)


How to use testing programs like Room EQ Wizard to get a baseline on your room and determine what else needs to be added and where


links to theatres here as examples of what correct setup looks like


I have seen the link to all the different types of insulation out there and the corresponding data but as far as I know the only ones that I know for sure will work in our applications are linacoustic( screen wall/first reflection ), OC703( screen wall/first reflection ), OC705( bass trapping ), R13/19 ( walls/ceiling/risers )

But there are many more brands that are available that can do the same thing that maybe cheaper/more accessable in your own hometown but I have no clue what the equivalent brand would be to the above as a example


what fabrics are commonly used for covering acoustic insulation and why


just a suggestion


----------



## pepar

Scruffy, any member here with the depth and breadth of knowledge to put such an FAQ together is a professional who sells their consultation services and/or acoustical treatments. And the rest of us are reading a lot here and wherever we can and trying to sort through it all on our own.


----------



## ScruffyHT

OK ... lets plow ahead then







... any thought on the bass trap idea for he rear of the room using the riser ? ... is it possible ?


----------



## pepar




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/14790899
> 
> 
> OK ... lets plow ahead then
> 
> 
> 
> 
> 
> 
> 
> ... any thought on the bass trap idea for he rear of the room using the riser ? ... is it possible ?



As long as they are taken solely as "thoughts" and not expert advice . . .


I don't think an enclosed riser stuffed with 'glass will do much. It will do "something" because it will have some natural resonance. How much I do not have a clue. Not being in a corner, it would not be in the best place to trap bass.


FWIW, I built my riser so that it would vibrate. Actually, I built it with the top deck "sprung" in anticipation of installing a motion transducer. (You can find it being built in the link in my sig.) Imagine my pleasant surprise when I found that it resonated at around 25Hz with a very satisfying amount of excursion.


----------



## Lonely Raven

Wow, so your riser is working as an absorber around the 25hz range?? Nice!



Since my theater setup was too complex for anyone but a paid pro to comment on, and I'm on a budget (which is pretty much spent at this point) I figured I'd just forge ahead and let my ears and REW be my guide.


So I just thought I'd throw this out there for others to check out. I'm building a semi-portable Super-Duper-Chunk that I can pull and move to another corner, test, retest, then try again somewhere else. Unfortunately I have very limited locations, so it's more an exercise in woodworking/design and practice in REW.


But here is what I'm working on:


































It's maybe a bit overbuilt, but it's strong enough to be able to pick up, carry up two flights of stairs (boy, that was fun!), drop in a corner and take measurements. It's 48" tall, and made from all 3/4" parts cobbled together from scraps. In fact, the frame is made from 2 X 4 I ripped down and the base and top are actually two different boards left over from speaker cab projects that I've glued end to end to make larger boards.







The insulation triangles are 34" face, the face of the cage is about 36" from corner to corner...it's a bit big and I should have trimmed it down, but I have a lot of space in this one corner. My plans include building it's twin to stack on top, and then a large grill that will velcro to the face of the twin base absorbers as many others have done with their Super-Chunks.


For those who mentioned about sub-traps helping with nulls, I completely agree. I did before and after tests last night, and I saw nulls and peaks in the 60Hz-80Hz smooth out...but only about 1.5db. Other frequencies...well, not really any change worth noting. Hopefully with the second half of this semi-portable SDC stacked in the corner, I'll get a full 3db of smoothing where I need it.


Next up will be some 4' X 4' free standing absorbers and some baseboard chunks (probably square rather then triangle), and I'm still working out if my rear wall should be diffusion or absorption to help with the flutter echo which is probably what's killing my response in the 500-900Hz range and again further up the audio scale.


----------



## pepar

Cool!


----------



## CJO

Lonely Raven- I've got some of what you are asking for in the beginning my my theater build.


CJ


----------



## Lonely Raven

I was confused as to what you were talking about...but then I saw all the research and links in your thread. WOW! That's a lot of info! You must have been researching for YEARS!


I have a suggestion for you about those movie posters, I'll PM you.


----------



## AnthemAVM

what are the thoughts about building superchuncks or using GIK tri traps?


I used the tri traps in the past, and didn't think they worked. Well I was wrong, and need some absorption for the bass in my room.


I am afraid the superchunks will lok like crap, as I am not a diy.


----------



## elee532

Anyone aware of a layman's "how-to guide" for using software to measure changes in my room acoustics as I add/move various acoustical treatments? Any inexpensive/freeware applications you reccomend? What type of mic would I need to take such readings?


Thanks.


----------



## AnthemAVM




> Quote:
> Originally Posted by *elee532* /forum/post/14796104
> 
> 
> Anyone aware of a layman's "how-to guide" for using software to measure changes in my room acoustics as I add/move various acoustical treatments? Any inexpensive/freeware applications you reccomend? What type of mic would I need to take such readings?
> 
> 
> Thanks.



Wouldn't REW work for what you are lokking for?


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14783904
> 
> 
> I either missed it or, more likely, ignored it. I understand the resistance that some have to spending the money that GOM costs and that leads to members coming up with all sorts of bargain fabrics that they found at the hardware store or fabric shop. Some of them are real eye-rollers.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Expensive as it is, GOM is designed for use in acoustical applications. Any fabric that isn't is a *pig in a poke*.
> 
> 
> Sorry, but that's just the way it is.
> 
> 
> - Jeff



Not sure what that means, but burlap will work just fine and no I don't have any test data.


----------



## elee532




> Quote:
> Originally Posted by *AnthemAVM* /forum/post/14796605
> 
> 
> Wouldn't REW work for what you are lokking for?



Thanks Anthem. Unfortunately, if I'm reading the requirements of REW correctly, a typical laptop soundcard is not sufficient (I have Lenovo X61 w/SoundMAX Integrated Digital HD Audio). Am I correct?


On the positive side, it seems I can use my SPL meter rather than having to buy some type of microphone.


I also looked at ETF, which sounds like it will work with my soundcard but costs much more than I can afford.


Any other reccomendations?


----------



## pepar




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14797093
> 
> 
> Not sure what that means, but burlap will work just fine and no I don't have any test data.



A "pig in a poke" is an idiomatic expression for something unknown, or taking a chance.


I don't think anyone said that burlap would not work.


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/14798806
> 
> 
> Thanks Anthem. Unfortunately, if I'm reading the requirements of REW correctly, a typical laptop soundcard is not sufficient (I have Lenovo X61 w/SoundMAX Integrated Digital HD Audio). Am I correct?
> 
> 
> On the positive side, it seems I can use my SPL meter rather than having to buy some type of microphone.
> 
> 
> I also looked at ETF, which sounds like it will work with my soundcard but costs much more than I can afford.
> 
> 
> Any other reccomendations?



Any "soundcard" with bi-directional capabilities will work. Laptops _usually_ do not meet that requirement, in which case an external USB solution is needed. SoundBlaster has one as do many others.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/14798861
> 
> 
> 
> 
> Quote:
> Originally Posted by *stepyourgameup* /forum/post/14797093
> 
> 
> Not sure what that means, but burlap will work just fine and no I don't have any test data.
> 
> 
> 
> 
> A "pig in a poke" is an idiomatic expression for something unknown, or taking a chance.
> 
> 
> I don't think anyone said that burlap would not work, but some may have aesthetic objections to it.
Click to expand...


Or fire/safety concerns and perhaps even code restrictions as well.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/14799875
> 
> 
> Or fire/safety concerns and perhaps even code restrictions as well.



I'm giving up on commenting on bargain materials members have found (or already bought). They are intent on using it anyway and don't to want to hear possible reasons why they shouldn't.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/14799929
> 
> 
> I'm giving up on commenting on bargain materials members have found (or already bought). They are intent on using it anyway and don't to want to hear why they shouldn't.



Sounds like the wiser way to go. At least, less stressful anyway.


----------



## CJO




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/14795491
> 
> 
> I was confused as to what you were talking about...but then I saw all the research and links in your thread. WOW! That's a lot of info! You must have been researching for YEARS!
> 
> 
> I have a suggestion for you about those movie posters, I'll PM you.



I have been researching for years, but I only started putting links up for a few months. It amazing how much accessible information is out there once you start looking for it.


CJ


----------



## stepyourgameup




> Quote:
> Originally Posted by *pepar* /forum/post/14799929
> 
> 
> I'm giving up on commenting on bargain materials members have found (or already bought). They are intent on using it anyway and don't to want to hear possible reasons why they shouldn't.



As far as fire safety is concerned, I just don't see it. I'm sure there are lots of things in my house that could be flammable if someone tried to light it. Are you guys saying that it might spontaneously combust or something? Maybe i'm missing something, which is entirely possible.


----------



## krasmuzik

Fire codes are about fire spread control - not about being flame proof - you would be amazed how fast burlap explodes into a fullout blaze - better fire starter than newspaper which flames out too quick. Polyester might just drip a bit before it flames itself out - for sure does not spread a fire.


There is a reason you don't see drapes made of burlap - ask your local fire chief who HAS seen it. Survival of the fittest - its your house and life- not mine.


If you don't care - buy a yard sample of each and lite it with a bic and see if the WAF cares.


----------



## kjohn

Just a quick ? for you guys I am using 6" thick bass trap panels should I put them in all four corners of the room or just the front.


----------



## pepar




> Quote:
> Originally Posted by *kjohn* /forum/post/14847784
> 
> 
> Just a quick ? for you guys I am using 6" thick bass trap panels should I put them in all four corners of the room or just the front.



Do as many corners as you can. I would start with the fronts.


----------



## kjohn

Thanks.


----------



## kjohn

Ok one more ? should I use 6" panels in the four corners of the room or 4" for bass absorption.


----------



## eugovector

According to the posted numbers, 6" is better, but 4" is sufficient. Correct me if I'm wrong, but 17"x24" super chunks outperform a 6" panel for the same amount of materials used (Am I remembering this incorrectly?)


----------



## pepar




> Quote:
> Originally Posted by *eugovector* /forum/post/14882236
> 
> 
> According to the posted numbers, 6" is better, but 4" is sufficient. Correct me if I'm wrong, but 17"x24" super chunks outperform a 6" panel for the same amount of materials used (Am I remembering this incorrectly?)



I used 2" x 24" x 48" to make my 17x17x24 SSC traps. One sheet made eight triangles which translates into 1.5 lineal feet of trap. A 6" x 24" x 48" sheet would make 4.5 lineal feet of that same size trap, but only 4 lineal feet of "trap" if used whole and straddling a corner. So, it makes more and is more effective as SSC trap. However, it is considerably more expensive _per lineal foot of trap_ to use 6" over 2".


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/14884291
> 
> 
> I used 2" x 24" x 48" to make my 17x17x24 SSC traps. One sheet made eight triangles which translates into 1.5 lineal feet of trap. A 6" x 24" x 48" sheet would make 4.5 lineal feet of that same size trap, but only 4 lineal feet of "trap" if used whole and straddling a corner. So, it makes more and is more effective as SSC trap. However, it is considerably more expensive _per lineal foot of trap_ to use 6" over 2".



Exactly right...well put.


Frank


----------



## mjg100

My room is not a dedicated room, but I do not see a better place to ask my questions regarding panel location. One end of my family room is set up for HT. All of my equipment is built into my front wall (see pic below). I am running a 7.1 system. I have RBH in-wall speakers for my front right, front left and rear speakers. My center channel is an RBH 661SE (cabinet speaker) and so are my side channel speakers. Not shown in the picture is my projection screen. Out to out of my screen is 8 feet so it lines up with the doors when they are open.


The width and depth of my room (end that I use) is not large, but since I use in-walls for most of my speakers the speaker distance is larger that what you would have for a small room. The end of the room that I use is 17' wide, 16' deep and I have a 17' flat ceiling (4,624 CF). One whole side is open (16' side). The whole room totals almost 12,000 CF and I have large crown molding at the ceiling. I have two large windows on my end of the room, one centered on the back wall (2nd pic) and another identical window on my side wall.


Much of what I have read has told me to cover as much of the front wall and back wall as posable. Then install panels at the reflection points on the side wall and panels or bass traps in the corners. Do the same rules apply with in-wall speakers? I am using 2"x24"x48" mineral wool, with wood frames covered with fabric. The frames are 2-3/4" of depth so that I have a 3/4" air space at the back of the panel.


Bass traps in the corners is out since this is a family room, but I could install a panel across the front right corner and the back right corner, but I would not want to stack a bunch of panels in these corners due to looks. Any and all suggestions direction is appreciated. Thank you.


----------



## Ethan Winer




> Quote:
> Originally Posted by *mjg100* /forum/post/14893644
> 
> 
> Then install panels at the reflection points on the side wall and panels or bass traps in the corners. Do the same rules apply with in-wall speakers?



Yes, in-wall speakers also have reflections off the side walls and ceiling. In a very wide or tall room where the reflection points are far away, the reflections are weaker simply due to distance. But with your width I'm pretty sure absorption on the side walls will help.


--Ethan


----------



## will1383




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14901912
> 
> 
> Yes, in-wall speakers also have reflections off the side walls and ceiling. In a very wide or tall room where the reflection points are far away, the reflections are weaker simply due to distance. But with your width I'm pretty sure absorption on the side walls will help.
> 
> 
> --Ethan



ugh. I really want to read through this thread as I am RIGHT at the point of buying my acoustical treatments to begin finishing up my walls, but man oh man I don't even know where to start in this thread.


----------



## mjg100




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14901912
> 
> 
> Yes, in-wall speakers also have reflections off the side walls and ceiling. In a very wide or tall room where the reflection points are far away, the reflections are weaker simply due to distance. But with your width I'm pretty sure absorption on the side walls will help.
> 
> 
> --Ethan



Thank you Ethan. Right now my plan is to install panels on my back wall since I am about 5 feet from it. My panels are 2.75" deep with 2" of rock wool and 3/4" air space at the back. I will also install this same panel on my side wall at all of the reflection points that I can hit. For the corners I will also use panels, except they will have 4" of rock wool. On my front wall I had planned on using the same panels (2.75" thick with 2" rock wool) as on my back wall. Only problem is I only have enough space for one or two panels, from the top of my screen to the floor. I have plenty of space above my screen, enough for seven panels.


The panels (2.75" thick with 2" rock wool) above the screen would be in the area between 9 feet and 16'-4" above the floor. Would panels that high help? Panels will not be used at the intersecting joint of wall and ceiling, but I do have large crown molding there.


My other question is in regards to the side wall. Since I have such high ceilings, would it help to stack two panels at the reflection points?


As to my ceiling, I was not too worried about reflections since it is so far away. I assume that the same rules regarding reflections apply to the ceiling that apply to the rear wall. Long distance, less of a problem. Besides my wife would not be too pleased if I placed panels over the crown molding.


Thank you,


Mike


----------



## will1383




> Quote:
> Originally Posted by *PamW* /forum/post/2275987
> 
> 
> Polyester quilt batting is the recommended upper covering right on the drywall - the hard part is finding the 1" thick stuff. I have discovered it at Hancock Fabrics. Also check quilt stores.
> 
> 
> pam





> Quote:
> Originally Posted by *proudx* /forum/post/2514889
> 
> 
> So treatment is a room 13ft by 20ft would need to be more aggressive on the side and rear walls than in a room 20X25ft.



This is all Very good information, and comes to where I am. My room is 210 square feet, 15' x 14'. It is a low-ceiling room, and will end up being roughly 7' 4" in height once the ceiling and floor is in place. So does this basically mean that I am better served not putting up drywall at all and spending the money on some type of acoustical treatment for all my walls? I want it to sound very good (I'm spending a fair buck on speakers, screen and projector) but I do have a limited budget that I need to use putting the walls in, sealing up the room and applying the acoustical treatments.


I thought that I could use isomax isolation clips and put two layers of 1/2" drywall, and then make 2" thick, 24" x 56" panels to place at the reflective points, and then a couple of larger acoustical panels in the rear of the room.


I didn't realize that I needed to make the entire front wall dead as a doornail... Are there any relatively inexpensive solutions that I can apply to the surface of the drywall I intended to put up? I also have one other, major problem with the front wall - it's where the door to the room is..


Is there something I should and could do to help deaden the door? put panels on the back of it? Buy a wooden door?


bty, great thread. I'm only on post number 80, though. lol


----------



## mjg100




> Quote:
> Originally Posted by *will1383* /forum/post/14906734
> 
> 
> ugh. *I really want to read through this thread* as I am RIGHT at the point of buying my acoustical treatments to begin finishing up my walls, but man oh man I don't even know where to start in this thread.



I am up to page 122. When you include reading the links it is a lot to read, but it has taught me a lot.


----------



## Ethan Winer




> Quote:
> Originally Posted by *will1383* /forum/post/14906734
> 
> 
> man oh man I don't even know where to start in this thread.



This thread is way too long and has too much contradictory information. My Acoustics FAQ is very detailed, and while a lot to read it's much more manageable.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *mjg100* /forum/post/14906896
> 
> 
> my plan is to install panels on my back wall since I am about 5 feet from it. My panels are 2.75" deep with 2" of rock wool and 3/4" air space at the back.



The wall behind you needs thicker absorption. You should use 4 inches thick minimum if possible.



> Quote:
> Would panels that high help?



Sure, if that's where the reflection points are.



> Quote:
> Since I have such high ceilings, would it help to stack two panels at the reflection points?



The size of the area covered is more a function of how far back you are from the speakers. They call it a reflection point but it's really an area.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14909832
> 
> 
> This thread is way too long and has too much contradictory information. My Acoustics FAQ is very detailed, and while a lot to read it's much more manageable.
> 
> 
> --Ethan



Perhaps if you put it in the public domain it wouldn't make it seem like you are using this thread for selling.


----------



## mjg100




> Quote:
> Originally Posted by *byte02553* /forum/post/14735148
> 
> 
> Attaching Acoustic Panels to ceiling......
> 
> 
> I have a quick question.....I will be attaching several 2' x 4' x 2" thick OC 703 panels to the ceiling to tame first reflections that come from the ceiling. These panels are light. I am going to bevel the fiberglass and cover with black GOM. I would rather not frame the fiberglass or hang using mollies and such...the hardware would be seen. Has anyone used any type of strong adhesive to attach these light panels to the ceiling? I have the panels that have the silver foil backing which would be the side attached to the ceiling. Am I crazy? Thanks.
> 
> 
> Wayne
> 
> ____________________________________________________________ _
> 
> No takers....no one has any suggestions? Surely there must be something that someone has used to attach these light panels to the ceiling without hardware...
> 
> 
> Wayne



Over the last several days I have read all of the posts in this thread and I recall reading about a guy that did just that. His ceiling was concrete so he used construction adhesive. If you are doing your whole ceiling you have several choices. You could run a 2" thick board around the perimeter of your room and run a 2" board across your room every 4 feet. Glue panels to the ceiling and use the 2" board to secure the fabric covering the ceiling.


You could grid your ceiling into slightly larger than 4' x 4' areas using a board 2-1/2" thick and use a 1" x 4" finished board on the bottom to make a ledge. Think upside down "T". This would hold up the 2" OC. Cover each piece of 2" OC with fabric. You could do this as a strip across the room rather than squares. You would need to screw or glue the middle of the panel so that it did not sag over time.


Added

You could glue a couple of small wood strips to the back of each 2" fabric wrapped OC panel and that should support each panel that sits on the "T" shaped ledge.


----------



## yngdiego




> Quote:
> Originally Posted by *mjg100* /forum/post/14910883
> 
> 
> Over the last several days I have read all of the posts in this thread and I recall reading about a guy that did just that. His ceiling was concrete so he used construction adhesive. If you are doing your whole ceiling you have several choices. You could run a 2" thick board around the perimeter of your room and run a 2" board across your room every 4 feet. Glue panels to the ceiling and use the 2" board to secure the fabric covering the ceiling.
> 
> 
> You could grid your ceiling into slightly larger than 4' x 4' areas using a board 2-1/2" thick and use a 1" x 4" finished board on the bottom to make a ledge. Think upside down "T". This would hold up the 2" OC. Cover each piece of 2" OC with fabric. You could do this as a strip across the room rather than squares. You would need to screw or glue the middle of the panel so that it did not sag over time.
> 
> 
> Added
> 
> You could glue a couple of small wood strips to the back of each 2" fabric wrapped OC panel and that should support each panel that sits on the "T" shaped ledge.




One word: Rotofast! Get their cloud hangers and it couldn't be easier. I use four per panel and they work great. Plus they hang down about 2-3" from the ceiling, which I think provides even better acoustical treatment.


I spaced mine about 6" in from the long sides and one foot from the short edges. This seems to support them quite well, and no sagging after almost a year of hanging.


----------



## will1383

Yuk. This thread does seem to be an interesting discussion at worst, but man it is very long, and I quite frankly don't have enough time just to read this thread... So... I suppose I'm off to read some other stuff and see if I can make sense of what I need.


I have a small room, which seems to warrant more absorbtion than diffusion, and tonight my wife and I finally got everything laid out with regards to screen location and seating locations.


So I need to nail down my construction methods by the end of this week so I can being wiring up and getting the materials to build the walls.


So now I have a 14wx15dx7'h that has a door on the front wall. I'm offsetting all of the seating and screen so this is going to be an interesting delimina in how I handle the acoustics in the room... Especially since the main seating is black leather, with the listening/viewing position 11ft from the front wall, and there is going to be a small 'bar' (more like table) with bar stools for additional seating behind the main sofa seating, so I have a bunch of accoustical stuff to figure out, including where to put the speakers.


So... I'm off to figure out how I'm going to construct the walls, and the stage, and figure out where to place my in wall speakers. The fronts will be going behind a perforated screen, so treating the front wall is going to be critical to starting things off properly.


I live in upstate NY, and I'm thinking I'm going to need professional help calibrating my room and final determination of proper acoustic handling... Hopefully, I'll be able to find someone locally...


----------



## mike_wassell

My home theater has an entrance door in one of the back corners. The room has 8’ ceilings and I am putting 8’ bass traps in the two front corners. My question is should I keep the base traps symmetrical or can I put a third bass trap in one of the rear corners and not the other?


Mike


----------



## pepar




> Quote:
> Originally Posted by *mike_wassell* /forum/post/14917861
> 
> 
> My home theater has an entrance door in one of the back corners. The room has 8' ceilings and I am putting 8' bass traps in the two front corners. My question is should I keep the base traps symmetrical or can I put a third bass trap in one of the rear corners and not the other?
> 
> 
> Mike



Do as many corners as you can. Assymetricity will not matter to the sound, only the eye. BTW, there are "corners" formed by the walls and the ceiling . . .


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/14909912
> 
> 
> Perhaps if you put it in the public domain it wouldn't make it seem like you are using this thread for selling.



Not sure what your point is. My Acoustics FAQ is on my personal site, and intentionally has no "sales" content. It's also free, and I even answer support questions for free. How much more "public domain" could I make it?










--Ethan


----------



## bigbadbob

OK. Starting from scratch with new construction. Left wall and front wall are ICF (insulated cement form) construction, back wall and right wall are 2x4 studs with sheet rock. Ceiling and non-icf walls insulated with R13. Screen wall is basic acoustically transparent fabric. Riser is 4" for first step with 10" after that filled with R13.


I have read this thread until my eyes hurt and everything now is clear as mud. Can someone explain to me in simple english terms (I'm not an acoustic techy by any means) what I need to do to my room for acoustic treatments. The rooms is 20' wide, 37' long and 8' ceiling. I have downloaded the Sweetspot from Guide to Home Theater and it said I may have 11 frequency zone issues. I don't want to spend a gazillion dollars just want a good sounding home theater. First row seating at 9', second at 15' and bar at 21' with 7.1 system. Denon, Klipsch with 50" Pioneer 5010.


Can someone help? I have looked into computer programs too and I am no techy at this either. I'm a meat and potatoes guy. I don't want to hire a home theater tech to design all of this either. Hope this isn't offensive to anyone.

RG


----------



## mjg100




> Quote:
> Originally Posted by *bigbadbob* /forum/post/14928274
> 
> 
> OK. Starting from scratch with new construction. Left wall and front wall are ICF (insulated cement form) construction, back wall and right wall are 2x4 studs with sheet rock. Ceiling and non-icf walls insulated with R13. Screen wall is basic acoustically transparent fabric. Riser is 4" for first step with 10" after that filled with R13.
> 
> 
> I have read this thread until my eyes hurt and everything now is clear as mud. Can someone explain to me in simple english terms (I'm not an acoustic techy by any means) what I need to do to my room for acoustic treatments. The rooms is 20' wide, 37' long and 8' ceiling. I have downloaded the Sweetspot from Guide to Home Theater and it said I may have 11 frequency zone issues. I don't want to spend a gazillion dollars just want a good sounding home theater. First row seating at 9', second at 15' and bar at 21' with 7.1 system. Denon, Klipsch with 50" Pioneer 5010.
> 
> 
> Can someone help? I have looked into computer programs too and I am no techy at this either. I'm a meat and potatoes guy. I don't want to hire a home theater tech to design all of this either. Hope this isn't offensive to anyone.
> 
> RG



Are your ICF (Insulated *Concrete* Form) walls covered with drywall? What are your goals? Are you looking for good sound only or are you looking for sound isolation along with good sound quality?


----------



## Weasel9992




> Quote:
> Originally Posted by *mjg100* /forum/post/14930417
> 
> 
> Are your ICF (Insulated *Concrete* Form) walls covered with drywall? What are your goals? Are you looking for good sound only or are you looking for sound isolation along with good sound quality?



Yep...need to know more about your goals. That's a pretty big space, so low end modal issues won't be as much of a problem, but intelligibility may be. I mean, you're always safe with the general answer: bass trapping in the corners and the back wall plus treatment at the reflection points for your seating area, but with HT things get a little more complicated once you start adding sconces, movie posters, aesthetic concerns, etc.


Frank


----------



## bigbadbob

No rock on the ICF yet at this point. I thought about just putting the sound treatments directly over the ICF and then covering those with fabric.


Goal: sound isolation isn't a huge concern - want a good sounding home theater. Not afraid to do some DIY stuff.


----------



## Weasel9992




> Quote:
> Originally Posted by *bigbadbob* /forum/post/14932409
> 
> 
> Goal: sound isolation isn't a huge concern - want a good sounding home theater. Not afraid to do some DIY stuff.



Cool...tons of DIY threads on this board and many others, so I won't belabor that here. Any way you can post a Google Sketchup of the space complete with furnishings/fixturing? Pictures maybe? It's really hard to tell you what to use and where to put it if I don't know what all to work around.


Frank


----------



## bigbadbob

I can't get Google Sketch-up to work. My wife is the computer genius not me. I hope this works... I attached an overview of the floorplan. Curved/false wall at the front of the room built 3 feet from front wall. Riser/stage covered with carpet and the rest of the floor hardwood/laminate.


----------



## mjg100

Received my FabricMate AudioFine samples today. Stuff looks good and meets NFPA 260. I will place my order tomorrow. If you have not looked at FabricMate, I would check them out.


----------



## zmisst




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14671866
> 
> 
> See Floyd Toole's new book, Sound Reproduction. Available on Amazon.





> Quote:
> Originally Posted by *pepar* /forum/post/14672153
> 
> 
> Thanks, headed to Amazon right now.
> 
> 
> - Jeff





> Quote:
> Originally Posted by *cavchameleon* /forum/post/14672286
> 
> 
> Add me to that! I've read some of Floyd Toole's papers, great insite. I'm heading over to Amazon also.
> 
> 
> Thanks!
> 
> Ray




So has anyone looked through this book? Care to give a review? summary? Any takeaways relevant to the discussions here? He is rumoured to say that early reflections can be good? (and thereby contradicting about 60% of all posts in this thread?)


----------



## Dennis Erskine

Early reflections are not necessarily bad. They are not good if the off axis response of your speakers is poor...then you want to absorb (but a flat sheet of fiberglass panel on the wall isn't going to help much). If the off axis response is good, then you'd be looking for diffusion.


----------



## SteveMo

I added 5/8" Poly Foam Caulk Saver under my 1/2" weather stripping to my HT door. It looks decent, holds very very tight, and the door opens very easy. When I turn the knob the door flys open about a foot. I will be measuring the difference between the weather stripping, and new installation later. I thought I would share since it works so well, and does not look all that bad. The door does not rattle or shake as it did. I tested with the ending to Matrix Revolutions and it passed with flying colors. Total cost, about $2.00.


----------



## ddgtr

I am planning on making bass traps for the four corners of my room out of 2" OC703 panels. Since it's only the bass that hangs out in the corners, do I need a reflective foil like an FRK to prevent absorption of mids and highs (which sound great in the room) installed on the hypotenuse of the bass traps?? Can I just glue a reflective foil instead of getting FRK panels and if yes, what is the best kind? Thanks in advance.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *ddgtr* /forum/post/14991991
> 
> 
> I am planning on making bass traps for the four corners of my room out of 2" OC703 panels. Since it's only the bass that hangs out in the corners, do I need a reflective foil like an FRK to prevent absorption of mids and highs (which sound great in the room) installed on the hypotenuse of the bass traps?? Can I just glue a reflective foil instead of getting FRK panels and if yes, what is the best kind? Thanks in advance.



For bass traps, you probably want panels thicker than 2".


----------



## ddgtr




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/14992875
> 
> 
> For bass traps, you probably want panels thicker than 2".



Sorry, I meant to say that I was going to cut those into triangles which I would then stack and glue together to fit in the corner...


Do I still want the reflective side of the FRK panel facing out to reflect highs and mids? Any substitutes for the FRK panels, like some kind of foil that would still absorb bass but reflect everything else?


Thanks.


----------



## LHD21

I just put together 6 knauf board panels. I've got a ton of polyester batting. Can I turn it into a worthwhile bass trap by framing it into a 4" thick enclosure? Is it worth the time or should I skip it?


----------



## pepar




> Quote:
> Originally Posted by *ddgtr* /forum/post/14992981
> 
> 
> Sorry, I meant to say that I was going to cut those into triangles which I would then stack and glue together to fit in the corner...
> 
> 
> Do I still want the reflective side of the FRK panel facing out to reflect highs and mids? Any substitutes for the FRK panels, like some kind of foil that would still absorb bass but reflect everything else?



That really depends on the acoustics of the entire room. Without knowing that, it is probably not possible to give the right answer. A generalization perhaps . . . which may or not be right for your room.


----------



## ddgtr

^^

The room is 15' x 26' rectangular shape, 8' ceilings. Except for the fact that I have standing bass waves in the 2 corners (16' side) where my tv, sub and fronts are located, the acoustics are really good - at least to my ears. So I was thinking to start with bass traps since that seems to be what most recommend. This is why I was asking about the FRK's reflective side, because I didn't want to mess with the sound too much, just want to get rid of the darn corner bass, which is really pronounced by the way... Opposite corners are fine...


----------



## pepar




> Quote:
> Originally Posted by *ddgtr* /forum/post/14995050
> 
> 
> ^^
> 
> The room is 15' x 26' rectangular shape, 8' ceilings. Except for the fact that I have standing bass waves in the 2 corners (16' side) where my tv, sub and fronts are located, the acoustics are really good - at least to my ears. So I was thinking to start with bass traps since that seems to be what most recommend. This is why I was asking about the FRK's reflective side, because I didn't want to mess with the sound too much, just want to get rid of the darn corner bass, which is really pronounced by the way... Opposite corners are fine...



Carpet? Drapes? Anyway, in the front I would NOT cover the traps with anything reflective. Some deaden the entire front wall. I did.


----------



## Ethan Winer




> Quote:
> Originally Posted by *ddgtr* /forum/post/14992981
> 
> 
> Sorry, I meant to say that I was going to cut those into triangles which I would then stack and glue together to fit in the corner



In that case you'll remove the facing. However, you could apply a new facing to what is now the front surface of the entire trap, which is really all those 2-inch edges. That not only reduces absorption at higher frequencies, but increases bass absorption too. Since these traps are in corners away from reflection points, reflections off the trap fronts will not be a problem.


--Ethan


----------



## Megalith

Bass trap question.


I know that it's best to treat all corners, but what are the integral spots (where would you start)? Tri-corners? Wall (side) corners? Ceiling corners?


Also, has anyone seen real measurements of Auralex Mega LENRD performance? I don't believe they're effective to 50 Hz.


----------



## ddgtr




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14996928
> 
> 
> In that case you'll remove the facing. However, you could apply a new facing to what is now the front surface of the entire trap, which is really all those 2-inch edges. That not only reduces absorption at higher frequencies, but increases bass absorption too. Since these traps are in corners away from reflection points, reflections off the trap fronts will not be a problem.
> 
> 
> --Ethan



Thank you everyone, I really appreciate the responses. Any specific facing I should be looking for?


----------



## SteveMo

Here are those measurements I promised with my two dollar door seal addition.


All seats measured before door seal

 


All seats mesured after door seal

 


Mic centered in front row before door seal

 


Mic centered in front row after door seal

 


Left seat before door seal

 


Left seat after door seal

 


Back row left seat before door seal (largest difference here. this is very close to the door)

 


Back row left seat after door seal

 


Please ignore the SPL, this was not calibrated.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Megalith* /forum/post/15000519
> 
> 
> Also, has anyone seen real measurements of Auralex Mega LENRD performance? I don't believe they're effective to 50 Hz.



Here are measurements that go down to the 63 Hz 1/3 octave band:
http://forum.studiotips.com/viewtopic.php?f=8&t=536 


The absorption trend is downward at this point. They hit peak absorption in the 100 Hz 1/3 octave band. But I would hesitate to conclude that they are not effective at 50 Hz.


- Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *Megalith* /forum/post/15000519
> 
> 
> I know that it's best to treat all corners, but what are the integral spots (where would you start)? Tri-corners? Wall (side) corners? Ceiling corners?



It depends on a lot of factors such as where your speakers are. This article describes a way to identify the best places for bass traps in any given room:

Pink noise aids placing bass traps 



> Quote:
> Also, has anyone seen real measurements of Auralex Mega LENRD performance? I don't believe they're effective to 50 Hz.



Any competent bass trap can get down to 50 Hz if it's large enough and you have enough of them. I'm sure MegaLENRDs can absorb 50 Hz if you have a bunch of them.


--Ethan


----------



## Megalith

Thanks guys.


Does anyone have any experience with the Primacoustic Australis?











I think they look way better than a MegaLENRD, but I'm assuming they are much less effective---though they are 36" in length, they only spread out 12" on each wall, and this is where it really matters, doesn't it?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Megalith* /forum/post/15006845
> 
> 
> they only spread out 12" on each wall, and this is where it really matters, doesn't it?



Yes, with bass traps size is very important.


--Ethan


----------



## zmisst




> Quote:
> Originally Posted by *zmisst* /forum/post/14986431
> 
> 
> So has anyone looked through this book? Care to give a review? summary? Any takeaways relevant to the discussions here? He is rumoured to say that early reflections can be good? (and thereby contradicting about 60% of all posts in this thread?)



To answer my own question, I've been looking through the Toole book and found that it has a few helpful sidebars labeled "Memo for listening room recommendations" which provide some quick highlights.


These recommendations are:


* add sound absorbing material to front wall


* for stereo listening, leave side walls reflective at first reflection points (sic!)


* add sound absorbing material or diffusers to center portion of rear wall


He specifically says the first reflections of lower frequencies are most useful to a desirable sense of "envelopment" and that using 2" panels on the side walls is a still a bad thing because even though the thin panels do allow the reflection of the lower frequencies, the "spectral fidelity" suffers since "the higher frequencies have been disproportionately attenuated"


The caveats to allowing side wall reflections are:


1) Should avoid flutter echoes between the sidewalls, typically from the side surround speakers. And so an additional "memo for listening room recommendation is to "use reflecting or scattering surfaces on walls opposite surround speakers to enhance envelopment" and help avoid flutter echoes.


2) while side wall reflections are defintely preferred in stereo applications (he states this repeatedly and refers to some experiement that someone did where listeners preferred music with side wall reflections), in multichannel applications, the surrounds may provide the desired sense of "envelopment" and side wall reflected sound may not be necessary and anyway maybe overwhelmed by the side surrounds.


3) recording control rooms which may want to add their own electronic delays/reflections to the sound, may not want to be distracted by the side reflections since they are analysing the music rather than just enjoying it.


So his view at the end of the day is that trying to absorb first order side wall reflections is generally not helpful and is likely even harmful.


Another common theme is that all absorption should be at least 3-4" thick so that it will be a broadband absorber rather just absorb the higher frequencies.


----------



## Weasel9992




> Quote:
> Originally Posted by *zmisst* /forum/post/15028582
> 
> 
> To answer my own question, I've been looking through the Toole book and found that it has a few helpful sidebars labeled "Memo for listening room recommendations" which provide some quick highlights.
> 
> 
> These recommendations are:
> 
> 
> * add sound absorbing material to front wall
> 
> 
> * for stereo listening, leave side walls reflective at first reflection points (sic!)
> 
> 
> * add sound absorbing material or diffusers to center portion of rear wall
> 
> 
> He specifically says the first reflections of lower frequencies are most useful to a desirable sense of "envelopment" and that using 2" panels on the side walls is a still a bad thing because even though the thin panels do allow the reflection of the lower frequencies, the "spectral fidelity" suffers since "the higher frequencies have been disproportionately attenuated"
> 
> 
> The caveats to allowing side wall reflections are:
> 
> 
> 1) Should avoid flutter echoes between the sidewalls, typically from the side surround speakers. And so an additional "memo for listening room recommendation is to "use reflecting or scattering surfaces on walls opposite surround speakers to enhance envelopment" and help avoid flutter echoes.
> 
> 
> 2) while side wall reflections are defintely preferred in stereo applications (he states this repeatedly and refers to some experiement that someone did where listeners preferred music with side wall reflections), in multichannel applications, the surrounds may provide the desired sense of "envelopment" and side wall reflected sound may not be necessary and anyway maybe overwhelmed by the side surrounds.
> 
> 
> 3) recording control rooms which may want to add their own electronic delays/reflections to the sound, may not want to be distracted by the side reflections since they are analysing the music rather than just enjoying it.
> 
> 
> So his view at the end of the day is that trying to absorb first order side wall reflections is generally not helpful and is likely even harmful.
> 
> 
> Another common theme is that all absorption should be at least 3-4" thick so that it will be a broadband absorber rather just absorb the higher frequencies.



His opinion on reflection points is common, but it requires a room that sounds good to start with...the hard boundaries around the listening position have to provide an balanced field with respect to the listening position. If they don't, and that's much more common, then absorption at the reflection points becomes important to avoid comb filtering, imbalanced imaging and other issues typical of first order reflection.


All that said, there are lots of people who like a room more lively...if you know that requirement going into it, you simply tailor your design strategy to accommodate it.


Frank


----------



## zmisst




> Quote:
> Originally Posted by *Weasel9992* /forum/post/15029207
> 
> 
> His opinion on reflection points is common, but it requires a room that sounds good to start with...the hard boundaries around the listening position have to provide an balanced field with respect to the listening position. If they don't, and that's much more common, then absorption at the reflection points becomes important to avoid comb filtering, imbalanced imaging and other issues typical of first order reflection.



One of the good qualities of the book is that many of his points are based on actual experiments/studies of people's listening preferences (usually blind) rather than just armchair theorizing after looking at FR graphs and waterfalls (although he does plenty of that too -- although usually to explain the preferences in the listening tests).


He cites tests of rooms with various degrees of simulated and real reflections. Of comb filtering he says that comb filtering isn't a bad thing as often people aren't sensitive to it (6.1.3) and while popular audio culture has conditioned people to think it is a technical flaw, it is actually "perceptually complex and beneficial" (7) and often people actually prefer it. (9.1).


He summarizes "We are left, though, with a problem: how to explain why the often mentioned comb filtering engendered by early refelctions is not a problem. None of the listeners heard it, or at least didn't comment on it except to say that they prefer sounds with reflections. . . . If there is a subjective response to comb filtering, it is that it appears to have a beneficial effect. (p. 140)


As far as imaging, his whole chapter 8 is about it and the conclusion is that first reflections help imaging. Specifically he wrote that


"When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.' Adding absorption to the front wall, behind the loudspeakers, reportedly improved image localization and reduced coloration." (p. 116)


----------



## Ethan Winer




> Quote:
> Originally Posted by *LHD21* /forum/post/14993407
> 
> 
> I just put together 6 knauf board panels. I've got a ton of polyester batting. Can I turn it into a worthwhile bass trap by framing it into a 4" thick enclosure? Is it worth the time or should I skip it?



If the raw panels are 4 inches thick they'll make fine bass traps. How you hang them is entirely up to you. A wood frame, wrapped in fabric - whatever you're DIY skills are capable of. The important thing is just to get them across corners.


--Ethan


----------



## Irv Kelman




> Quote:
> Originally Posted by *zmisst* /forum/post/14986431
> 
> 
> So has anyone looked through this book? Care to give a review? summary? Any takeaways relevant to the discussions here? He is rumoured to say that early reflections can be good? (and thereby contradicting about 60% of all posts in this thread?)



I have not read Floyd's latest book but let's be sure we are talking apples to apples.


We know the audio setup for home theater (multi channel) is different from stereo.


We generally optimize for the dominate use. Or better yet have two different rooms.


Another consideration is the processor. Yamaha and Lexicon are two that create their own reverberant sound fields and work better in a more sound dampened environment.


From the discussion, it sounds like Floyd is referring to Stereo envelopment. That does not go against the general principals we trust for home theater.


The final decision on the acoustical treatment of the room depends on equipment and use.


----------



## Weasel9992




> Quote:
> Originally Posted by *zmisst* /forum/post/15029887
> 
> 
> "When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.' Adding absorption to the front wall, behind the loudspeakers, reportedly improved image localization and reduced coloration." (p. 116)



Hmmmm...interesting. I like his approach...I'm going to have to read that book. The only thing is, my own experience is that discriminating listeners *definitely* notice comb filtering. They don't know what to call it, but they hear it...and treatment at or around the reflection points generally clears it up.


I do agree that there are varying preferences in terms of liveliness in a room. Some people like lots of bounce, others like it very dry.


Frank


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/15028582
> 
> 
> So his view at the end of the day is that trying to absorb first order side wall reflections is generally not helpful and is likely even harmful.



He is not alone in this, but he does not have the Verizon network behind him either. I found nothing harmful in my room by adding 2" 'glass at the front sidewall reflection points. To the contrary, all of my FRP absorbers incrementally added clarity and mains/surrounds integration. The REAR wall absorber made the single largest incremental improvement. After reading Toole's paper, I have considered swapping absorption for diffusion on the ront side walls. But the absorbers there were not harmful.


Just my $.02.


- Jeff


----------



## zmisst




> Quote:
> Originally Posted by *Irv Kelman* /forum/post/15031253
> 
> 
> We know the audio setup for home theater (multi channel) is different from stereo.
> 
> 
> We generally optimize for the dominate use. Or better yet have two different rooms.
> 
> 
> Another consideration is the processor. Yamaha and Lexicon are two that create their own reverberant sound fields and work better in a more sound dampened environment.
> 
> 
> From the discussion, it sounds like Floyd is referring to Stereo envelopment. That does not go against the general principals we trust for home theater.



Floyd discusses multichannel quite a bit -- his whole final chapters where he gives specific recommendations are based on multichannel rooms and he still maintains lateral reflections are at worst neutral (and may even be beneficial) there also. Here are few relevant quotes:


"The locations of the first side-wall reflections at the front of the room are specified as areas for optional treatment. Leaving these areas as flat wall surfaces provides an open and spacious soundstage for those customers who listen in stereo. In television and movies these reflections will "soften" the image of the commonly dominant center channel. Well-designed wide-dispersion front loudspeakers will generally sound better in the presence of lateral reflections. When multiple channels are operating simultaneously, these reflections are swamped by the recorded sounds and become neutral factors. So, the effects of these side-wall reflections range from neutral to slightly beneficial. In any event, they are not large effects, so the choice can be left to the designer."


"In professional environments, like recording control rooms, it has been common practice to absorb these side-wall reflections from the front loudspeakers. As discussed in Chapter 8, most recreational listeners have voted that they enjoy them in stereo reproduction. In a multichannel context, the matter is open for discussion. If the surround channels are active, it is probable that the modest spatial contributions of these front-channel reflections will be masked. If only the front channels, especially the center channel, are active, it is possible that a small spatial effect may be beneficial. "


and also,


"The most common problem in custom home theaters is that they are too 'dead.' In conversation, voices sound muffled, and more than the usual amount of vocal effort is required. It is not a relaxing situation. However, I know of designers who have done this deliberately to make the theater seem 'special.'"


He also mentions Lexicon and THX surround processing and suggests that those surround processing modes sound better in part because they add their own "artificial" reflections to the sound from the front speakers -- in a sense duplicating the those reflections that some go to great lengths to abolish. And since the surround speakers are usually much louder than the real reflections, the surrounds will tend to cover up the front reflections -- although it of course depends on the audio engineer doing the surround tracks and the listening mode selected.


Bottom line for me is, I've delayed for months now doing my first order side wall treatment (couldn't figure out how to do it so that it looked nice); things sound great without it, and with Toole's suggestion (backed up by real empirical data) that I'm probably better off with reflective walls at that area, I'm happy to not bother with it.


Two caveats to the benefits of first order reflections:


1) Toole does suggest absorbing/diffusing the first order reflections from both the ceiling and the floor. -- I don't recall reading why those are different. I think he suggests absorbing the floor reflections because having carpet is part of a standard room anyway and very helpful in getting the RT down. (Although throughout the book he insists that all absorption has to be 3-4" thick so that it is a broadband absorber, and that would seem to be impossible for any normal carpet even with the thickest pad. So the floor absorption is going to have to be of only the higher frequencies, but that seems unavoidable.)


2) As alluded to by Dennis above, Toole does mention that speakers with poor off-axis repsonse may benefit from first reflection absorption. In other words, if your front speakers send out the equivalent of acoustic flatulence to the side to be reflected off the walls, then you probably don't want that acoustic flatulence to be bounced back to you, so you might as well absorb it.


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/15038431
> 
> 
> "The locations of the first side-wall reflections at the front of the room are specified as areas for optional treatment. Leaving these areas as flat wall surfaces provides an open and spacious soundstage for those customers who listen in stereo. In television and movies these reflections will "soften" the image of the commonly dominant center channel. Well-designed wide-dispersion front loudspeakers will generally sound better in the presence of lateral reflections. When multiple channels are operating simultaneously, these reflections are swamped by the recorded sounds and become neutral factors. So, the effects of these side-wall reflections range from neutral to slightly beneficial. In any event, they are not large effects, so the choice can be left to the designer."
> 
> 
> "In professional environments, like recording control rooms, it has been common practice to absorb these side-wall reflections from the front loudspeakers. As discussed in Chapter 8, most recreational listeners have voted that they enjoy them in stereo reproduction. *In a multichannel context, the matter is open for discussion.*



To the extent that there is discussion, it is good. My understanding, however, is that the goal is to get our theater acoustics - and therefore "sound" - as neutral as possible so that we hear what the mixdown engineer heard. New technologies such as Audyssey even factor _time_ into the filters. What purpose would analyzing over time have if not to correct for reflections and RT? Early reflections, from any angle, confuse the brain. Similarly, for our eyes, our displays need to be calculated to the standard used by the team that produced the movie.


----------



## Irv Kelman




> Quote:
> Originally Posted by *zmisst* /forum/post/15038431
> 
> 
> Bottom line for me is, I've delayed for months now doing my first order side wall treatment (couldn't figure out how to do it so that it looked nice); things sound great without it, and with Toole's suggestion (backed up by real empirical data) that I'm probably better off with reflective walls at that area, I'm happy to not bother with it.



Keeping in mind that my perspective is home theater rather than multi channel music, I don't think there is a conflict between Floyd's findings and generally held small space acoustical practice.


Remember, our goal in home theater is to take a movie soundtrack mixed for a commercial theater space and reproduce it in a small space as the director intended. Not an easy task or we would not spend so much time and energy searching for the Holy Grail of perfect home theater acoustics.


As we perfect the space and introduce more capable electronics, we discover more flaws in the soundtracks we play. Some time accurate sound reproduction does not sound right when compared to what we are used to hearing. Most of us are happy with what we have until we experience another theater that is more immersive.


Irrespective of all this chatter, the idea in movie watching is the suspension of disbelief. Once you are satisfied that you have accomplished that, all else is superfluous.


----------



## pepar




> Quote:
> Originally Posted by *Irv Kelman* /forum/post/15040194
> 
> 
> Remember, our goal in home theater is to take a movie soundtrack mixed for a commercial theater space and reproduce it in a small space as the director intended. Not an easy task or we would not spend so much time and energy searching for the “Holy Grail” of perfect home theater acoustics.



Many - and more and more - movies are remixed for home theater.


----------



## glaufman




> Quote:
> Originally Posted by *pepar* /forum/post/15040625
> 
> 
> Many - and more and more - movies are remixed for home theater.



Perhaps, but this remixing automatically takes a "one size fits all" approach, whereas everyone's home theater has different properties...


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/15040708
> 
> 
> Perhaps, but this remixing automatically takes a "one size fits all" approach, whereas everyone's home theater has different properties...



Well sure. And that is why everyone's home theater should be as neutral as possible removing (as many/much of) the variables as possible allowing us to hear what the mixer heard. I'm just not buying that the room should contribute to or subtract from what was heard in the studio.


----------



## Dennis Erskine




> Quote:
> Hmmmm...interesting. I like his approach...I'm going to have to read that book. The only thing is, my own experience is that discriminating listeners *definitely* notice comb filtering. They don't know what to call it, but they hear it...and treatment at or around the reflection points generally clears it up.



The are not hearing comb filtering which is part of the problem (particularly if they are sitting in a chair and not moving around). They are hearing other artifacts (generally horrible off axis response) and it is being called "comb filtering".



> Quote:
> Many - and more and more - movies are remixed for home theater.



And this practice MUST come to a screeching halt (this view point is held even by the Audyessey folk). It is horse manure, BS and krap. (Strong words, eh?)


Heres a couple of the problems with it. First, the DVD specification provides a significant number of "flags" these producers and re-mixers think they are too good to use (and manufacturers are too cheap to read). Since a flag is not being set (or used) the consumer has no clue he has just purchased a 'remix' and his bzillion dollar reference room has been carefully designed and calibrated to meet the acoustic specifications of a SMPTE reference room and can't figure out why his new BR disk sounds nasty. Since there's no flag, there's no chance to modify playback parameters.


Secondly, what are the acoustic parameters of "home theater"? This has never been defined. So basically these remixes are being done different by every post house and to a different definition of what a "standard" home playback space is (size, shape, RT, etc., etc.,). So, in the end, regardless of how much money you have, or how many smarts you can apply, you have absolutely no clue as to whether this remix is going to sound good in your RV's back seat, your living room, or your home theater (regardless of your definition of home theater). If the clowns who singularly decided this was a good idea want to persist with this hair brain idea, they need to (1) leave the original sound track available on the disk for use; (2) use the flags the DVD gods left for them to use; and, (3) define the acoustic parameters of the "standard home play back space" so we know what we are building to.


Multichannel music DVD's failed in the market for exactly the same reason ... every sound engineer had a different definition of what the proper playback space ought to be and the consumer wasn't about to pay a premium for a recording that might, or might not, sound good in his system. These "clowns", who believe they are smarter than we are have forgotten that it is you and I who are paying their salaries and they are close to being fired.


End of rant (but if you're one of the "clowns" I haven't spoken with already, please feel free to contact me...I'll be more than happy to read the riot act to you directly).


----------



## Irv Kelman




> Quote:
> Originally Posted by *glaufman* /forum/post/15040708
> 
> 
> Perhaps, but this remixing automatically takes a "one size fits all" approach, whereas everyone's home theater has different properties...



Beyond that, it opens a whole new "Can of worms".


Movie soundtracks are mixed to an international standard. THX. Ltd pioneered small space reproduction standards to preserve the integrity of the sound as mixed. Proprietary circuits were licensed to processor manufacturers to modify the X-Curve for home (small space) reproduction.


If a movie is re-mixed for DVD, those of us with more sophisticated processors will have to manually adjust for it. If not our equipment will add processing to a "corrected" soundtrack.


Isn't this fun!! ;-)


OOPS!! I was typing this when Dennis answered it. He explained it much better than I can.


----------



## will1383

Dennis,


Is there a way you would be willing to speak with me over the phone regarding some specific issues I have in my HT design that are related to the acoustical properties of the room? This thread, as informative as it is, is just way to overwelming for me to make any sense of due to the sheer amount of varying philosophies.


If so, how can I get in contact with you?


Thanks in advance,

D


----------



## glaufman




> Quote:
> Originally Posted by *Irv Kelman* /forum/post/15040950
> 
> 
> THX. Ltd pioneered small space reproduction standards to preserve the integrity of the sound as mixed. Proprietary circuits were licensed to processor manufacturers to modify the X-Curve for home (small space) reproduction.
> 
> 
> If a movie is re-mixed for DVD, those of us with more sophisticated processors will have to manually adjust for it. If not our equipment will add processing to a "corrected" soundtrack.



True. Being THX certified myself, this is one area where I disagree with THX... their new X-curve is precisely one of the problems, it assumes a certain room response for the home theater, yet I've never seen them define exactly what that response is, so the odds of it being the perfect shape for any given room are astronomical, and it becomes more of a gimmick than a useful feature...


----------



## Dennis Erskine

Actually, it is pretty well defined. It defines what the room response ought to be (or at least the starting point for it). The skill is either designing a room with proper response and/or proper calibration of the room. The X curve wasn't just pulled out of the air, it was based upon a large body of evidence and research suggesting what listeners prefer. Even THX says it's not a law, it is a reasonable starting point.


----------



## glaufman




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15041104
> 
> 
> Actually, it is pretty well defined. It defines what the room response ought to be (or at least the starting point for it). The skill is either designing a room with proper response and/or proper calibration of the room. The X curve wasn't just pulled out of the air, it was based upon a large body of evidence and research suggesting what listeners prefer. Even THX says it's not a law, it is a reasonable starting point.



Well then, please point me to it...

nonetheless, this still is a contradiction, as THX always spouts "what the director intended" and not "what people prefer to hear"


----------



## Dennis Erskine

You'd need to go back to the THX folks to get that from them. I can't pass it around.


Sure, "what the director intended" is true; but, what the director intended was determined in a room considerably larger (and what do you think their target curve was?). Part of what the director intends is that you enjoy (prefer) the sound. More to the point, those judging the picture in the AMPAS reference room(s) prefer the sound (Clarity, Focus, Envelopment, Response & Dynamics).










I'm certain your THX texts (and the class room sessions) discussed the purpose and history of the "X curve".


----------



## zmisst




> Quote:
> Originally Posted by *pepar* /forum/post/15039517
> 
> 
> Early reflections, from any angle, confuse the brain.



Toole's chapters 6 and 7 and in many places throughout the whole book, refer to studies and experiments that say just the opposite: When tested and asked in controlled experiments, people prefer early reflections for music and early reflections help speech intelligibilty.


So long as reflections are not so delayed that they start to resemble echoes, people prefer them.


Toole's experiments seem to indicate that this is just a psychoacoustic fact. And not too surprising when you consider that most people grow up and develop their listening skills indoors in fairly reflective rooms. (How could we learn anything in school classrooms and college lecture halls if our brains were "confused" by early reflections?)


Use the "Search inside this book" function on his actual book text in Amazon and read many of the pages on this and see if it seems plausible to you -- it did to me. Although I'd love to hear of contrary evidence.


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/15041962
> 
> 
> Toole's chapters 6 and 7 and in many places throughout the whole book, refer to studies and experiments that say just the opposite: When tested and asked in controlled experiments, people prefer early reflections for music and early reflections help speech intelligibilty.
> 
> 
> So long as reflections are not so delayed that they start to resemble echoes, people prefer them.
> 
> 
> Toole's experiments seem to indicate that this is just a psychoacoustic fact. And not too surprising when you consider that most people grow up and develop their listening skills indoors in fairly reflective rooms. (How could we learn anything in school classrooms and college lecture halls if our brains were "confused" by early reflections?)
> 
> 
> Use the "Search inside this book" function on his actual book text in Amazon and read many of the pages on this and see if it seems plausible to you -- it did to me. Although I'd love to hear of contrary evidence.



I did not stay at a Holiday Inn Express last night; all I know is what I heard in my theater when I added the 2" OC SelectSound Black at the first reflection points on the left and right front walls, the ceiling and the rear wall. My entire front wall was already covered with 2" of a J-M product.


I have read Toole's paper, but not the referenced book. I do not know how to reconcile his work and what I heard.


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/15041156
> 
> 
> Well then, please point me to it...
> 
> nonetheless, this still is a contradiction, as THX always spouts "what the director intended" and not "what people prefer to hear"



Isn't the director present when remix for home theater is done? If so, given the different environment to simulate a small home theater, wouldn't the remix also be the artist's intention?


----------



## pmeyer

I have trouble basing my decisions on studies that state 'people prefer' A or B.


The reason consumer electronics stores crank up the saturation and brightness on their displays is because it catches peoples eyes and 'looks better' than the calibrated set next to it. That doesn't mean that the oversaturated display is accurately reflecting the intent of the creator of the material, or that it is 'better'. However, you could do a study showing that people 'prefer it'.


I don't mind if my HT is 'dead' for conversation. I've got 8 recliners in two rows all facing forward. It is NOT a space that is amenable to conversation. I'm not going to optimize my space for stereo music listening or for conversation. It's for films.


I've got a 7.1 system. I want the room pretty dead. If the sound track editor wants a 'lively' room, he can make it using the surround speakers.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Irv Kelman* /forum/post/15031253
> 
> 
> We know the audio setup for home theater (multi channel) is different from stereo. We generally optimize for the dominate use. Or better yet have two different rooms.



I don't know why that would be the case. I have a fabulous room that works perfectly for both stereo and multi-channel. Whether you're using only the front left and right speakers, or watching a movie (I believe most movies have music), the goals are identical:


* Tight controlled bass with minimal peaks and nulls and ringing.


* No early reflections that harm imaging and cause comb filtering.


* A low acoustic noise floor so ambient sounds don't mask low-level detail.


--Ethan


----------



## Dennis Erskine




> Quote:
> Isn't the director present when remix for home theater is done? If so, given the different environment to simulate a small home theater, wouldn't the remix also be the artist's intention?



In that space. You're missing the other half of the problem. We have to recreate what the director heard and that cannot be done unless we can go back to the baseline ... and there's no baseline. We have no clue what the acoustic properties of the post room were like (or not) as the case may be.



> Quote:
> I don't know why that would be the case.



Very simple. With two channel you have to create the entire immersive effect with two speakers. With multi-channel, you do not want the reflections from the mains overcoming the effects (or surround) channels. Further, when stereo is mixed, the reflected sounds from the venue are recorded in the front speakers along with the direct sound. Even the way the reflected sounds are mixed is different between a multi-channel and two channel mix. You may like what you hear, but, that does not necessarily mean "accurate".


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Very simple. With two channel you have to create the entire immersive effect with two speakers. With multi-channel, you do not want the reflections from the mains overcoming the effects (or surround) channels. Further, when stereo is mixed, the reflected sounds *from the venue* are recorded in the front speakers along with the direct sound. Even the way the reflected sounds are mixed is different between a multi-channel and two channel mix. You may like what you hear, but, that does not necessarily mean "accurate".



Are you speaking from a live performance perspective?


----------



## Dennis Erskine




> Quote:
> Are you speaking from a live performance perspective?



No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15048074
> 
> 
> No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.



It was that "from the venue" that caused me to ask that question. That, in my mind, suggests symphonic music when most of my home theater usage is for movies. No venue there, so no venue to recreate in my theater.


IMO, Ethan nailed it:


* Tight controlled bass with minimal peaks and nulls and ringing.


* No early reflections that harm imaging and cause comb filtering.


* A low acoustic noise floor so ambient sounds don't mask low-level detail.


Oh, and comfortable seating with cup holders, too.


----------



## glaufman




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15048074
> 
> 
> No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.



Well, certainly not in the mass market, but I do remember something about an experiment where 2 mics (L+R) were placed in the ears of the dummy head which was in turn placed in a concert hall and a recording made which could then reproduce very well the complete effects of a live performance, at least when listened to on headphones...


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15048074
> 
> 
> No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.



I know, I know. You would not be surprised to hear that I get lots of flack from the Stereophile crowd when I make that point.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15048074
> 
> 
> No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.





> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15049661
> 
> 
> I know, I know. You would not be surprised to hear that I get lots of flack from the Stereophile crowd when I make that point.



What would account for the great 2-ch listening possible with high end headphones? No "room reflections" there, just the ambiance in the recording. And a v-e-r-y neutral "room."


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/15049805
> 
> 
> What would account for the great 2-ch listening possible with high end headphones? No "room reflections" there, just the ambiance in the recording. And a v-e-r-y neutral "room."



Sorry but that is nonsense. Listening to stereo over headphones will not provide anything that approaches recreation of the original ambiance and soundstage. It will be very clear due to the avoidance of listening room acoustics but everything else is in your head.


Now, with binaural recordings (also 2 channel), you can recreate some/much of the original acoustic since the recording encompasses the HRTF of the dummy head. How much each listener resembles the dummy is for him to decide.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *glaufman* /forum/post/15049412
> 
> 
> Well, certainly not in the mass market, but I do remember something about an experiment where 2 mics (L+R) were placed in the ears of the dummy head which was in turn placed in a concert hall and a recording made which could then reproduce very well the complete effects of a live performance, at least when listened to on headphones...



That is not stereo, by definition, but binaural and there are very, very few such recordings available.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15050007
> 
> 
> Sorry but that is nonsense. Listening to stereo over headphones will not provide anything that approaches recreation of the original ambiance and soundstage. It will be very clear due to the avoidance of listening room acoustics but everything else is in your head.
> 
> 
> Now, with binaural recordings (also 2 channel), you can recreate some/much of the original acoustic since the recording encompasses the HRTF of the dummy head. How much each listener resembles the dummy is for him to decide.



The impression that I continue to get here is that the proponents of counting on reflections in the room to create envelopment are talking about recordings of live music. With movies - and music recorded in a multitrack studio and subsequently mixed down - the only "environment" is the one created artificially by the engineer/producer/director. In that case, I just don't see how "proper" room acoustics create envelopment. The envelopment comes from the surround channels. Where is the nonsense in that?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/15050057
> 
> 
> The impression that I continue to get here is that the proponents of counting on reflections in the room to create envelopment are talking about recordings of live music.



Indeed. Guilty.











> Quote:
> With movies - and music recorded in a multitrack studio and subsequently mixed down - the only "environment" is the one created artificially by the engineer/producer/director. In that case, I just don't see how "proper" room acoustics create envelopment. The envelopment comes from the surround channels. Where is the nonsense in that?



The nonsense comes from the statements about headphones. Even given the arbitrary and artificial sound field created by the engineers for speaker listening, there's no way that headphones can reproduce it. Elimination of the presumed room interactions and HRTF precludes it.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15050100
> 
> 
> 
> The nonsense comes from the statements about headphones. Even given the arbitrary and artificial sound field created by the engineers for speaker listening, there's no way that headphones can reproduce it. Elimination of the presumed room interactions and HRTF precludes it.



Ummm, ever listen to Moody Blues' "Legend Of A Mind" with Timothy Leary's astral plane on headphones?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/15050338
> 
> 
> Ummm, ever listen to Moody Blues' "Legend Of A Mind" with Timothy Leary's astral plane on headphones?



Nope, with or without phones. The issue is not whether you can gain enjoyment from this but how it presents the recorded material. If you like it, go for it.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15050535
> 
> 
> Nope, with or without phones. The issue is not whether you can gain enjoyment from this but how it presents the recorded material. If you like it, go for it.



High end, in-ear monitors don't present the material, they _reproduc_e it and nearly 100% faithfully at that.


I'm not proposing them or any other "headphone" for multichannel home theater, but rather as a way of making my point about the most neutral room being the best. A few cubic millimeters of ear canal are as neutral as it can get.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/15050629
> 
> 
> High end, in-ear monitors don't present the material, they _reproduc_e it and nearly 100% faithfully at that.
> 
> 
> I'm not proposing them or any other "headphone" for multichannel home theater, but rather as a way of making my point about the most neutral room being the best. A few cubic millimeters of ear canal are as neutral as it can get.



Forgive the interruption but I think (correct me if I'm wrong Kal) the point Kal is making is that headphones cannot recreate the effect that a concert hall has on the sound in regards to spaciousness. By design, they physically never could. While we certainly hear sound pass from left to right, the perception of any sound depth front-to-back is added by the listener.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/15050696
> 
> 
> Forgive the interruption but I think (correct me if I'm wrong Kal) the point Kal is making is that headphones cannot recreate the effect that a concert hall has on the sound in regards to spaciousness. By design, they physically never could. While we certainly hear sound pass from left to right, the perception of any sound depth front-to-back is added by the listener.



I understand Kal's concert hall-centric point, but this is the Acoustical Treatments Master Thread thread on the Dedicated Theater Design & Construction forum and most home theaters are for enjoying 5.1 to 7.1 multi-channel movies. The "environment" and "envelopment" are in the surrounds.


Me mentioning headphones was obviously a mistake.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/15050629
> 
> 
> High end, in-ear monitors don't present the material, they _reproduc_e it and nearly 100% faithfully at that.
> 
> 
> I'm not proposing them or any other "headphone" for multichannel home theater, but rather as a way of making my point about the most neutral room being the best. A few cubic millimeters of ear canal are as neutral as it can get.



I am not disputing the neutrality of decent in-ear monitors. It is that almost all program material is mixed and mastered for in-room reproduction. Whether the ambiance is real or synthetic, it was monitored and was intended for reproduction over speakers in an acoustic space. Eliminate the space (with everything that implies) and the HRTF and the intended effect cannot be recreated.


----------



## zmisst




> Quote:
> Originally Posted by *pepar* /forum/post/15042476
> 
> 
> all I know is what I heard in my theater when I added the 2" OC SelectSound Black at the first reflection points on the left and right front walls, the ceiling and the rear wall. My entire front wall was already covered with 2" of a J-M product.
> 
> 
> I have read Toole's paper, but not the referenced book. I do not know how to reconcile his work and what I heard.



It occurs to me that perhaps what you heard was simply the benefit of having additional absorption/diffusion in your room. That you happened to put it at the first reflection didn't really matter. Try moving the panels above or below the first reflection line and you might find that you like that even better: -- keeping the additional absorption in the room while also getting the benefit of the envelopment and spatial imaging (and low IACC) that listeners in Toole's experiments prefer from first reflections.


Also, another tidbit in Toole's book that is that he points out the 2" absorbers covered with GOM are actually reflecting and diffusing quite a bit rather than acting as good broadband absorbers. Because they are only 2" thick, the lower frequencies are mostly being reflected; and while GOM is often thought of as acoustically transparent, Toole has tests that show that GOM FR701 it is actually quite reflective of higher frequencies, especially at the grazing angles that would be present on side wall first reflections (p. 483, showing that uncovered fiberglass attenuates 6k-20k Hz about 25-40db while fiberglass covered with GOM FR701 only attenuates that same range ~12-20db.)


So 2" side wall "absorbers" are actually reflecting much of the low and high frequencies and absorbing mostly in the midrange.


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/15076248
> 
> 
> It occurs to me that perhaps what you heard was simply the benefit of having additional absorption/diffusion in your room. That you happened to put it at the first reflection didn't really matter. Try moving the panels above or below the first reflection line and you might find that you like that even better: -- keeping the additional absorption in the room while also getting the benefit of the envelopment and spatial imaging (and low IACC) that listeners in Toole's experiments prefer from first reflections.
> 
> 
> Also, another tidbit in Toole's book that is that he points out the 2" absorbers covered with GOM are actually reflecting and diffusing quite a bit rather than acting as good broadband absorbers. Because they are only 2" thick, the lower frequencies are mostly being reflected; and while GOM is often thought of as acoustically transparent, Toole has tests that show that GOM FR701 it is actually quite reflective of higher frequencies, especially at the grazing angles that would be present on side wall first reflections (p. 483, showing that uncovered fiberglass attenuates 6k-20k Hz about 25-40db while fiberglass covered with GOM FR701 only attenuates that same range ~12-20db.)
> 
> 
> So 2" side wall "absorbers" are actually reflecting much of the low and high frequencies and absorbing mostly in the midrange.



You make some good points. The 2" 'glass was selected knowing that it did not reach deep because I planned on adding superchunk bass traps (linked in my sig) to deal with LF and because 4" would have encroached on the walk path and just generally detracted aesthetically.


I was not aware that FR701 reflected/diffused higher frequencies at grazing angles and perhaps that is a fortunate thing in my case. All I know is that everything is crystal clear. Dialog, whether one person or many, whispering or shouting, is equally clear. People speaking in the foreground sound like they are in the foreground and distant voices sound distant. That "gross" distance difference in their voices might be expected, but the acoustic depth perception is there with much, much smaller variations as well. The overall front sound stage is quite detailed as well with the width you'd expect, but with depth as well. Envelopment? That comes from the surrounds.


I've been in rooms where it seemed like if you just turned it up a bit more the dialog could be understood. Of course, that raised the cacaphony as well and the dialog was still obscured. One of the rooms I've been in that had that problem was MINE. In it's previous incarnation I had only drapes on the front side walls. I had no other treatments. It was terrible.


I do not know what I would have "preferred" if I were one of Toole's test subjects, but I know I really like my theater's sound as do all of the guests - many of them fellow home theater enthusiasts - that drop by.


----------



## harrisonbound

My front wall is 80" tall and about 13 feet wide.... I covered it floor to ceiling with OC 703 and now want to cover it with GOM... So, what is the best way to do this... I have wood strips on all four sides... However, the material is maximum 64" wide.... So, I am going to have a seem..... Do I sew the material together? I am not good at sewing.... Is there an easier way to do this? Thoughts?


----------



## will1383




> Quote:
> Originally Posted by *harrisonbound* /forum/post/15093438
> 
> 
> My front wall is 80" tall and about 13 feet wide.... I covered it floor to ceiling with OC 703 and now want to cover it with GOM... So, what is the best way to do this... I have wood strips on all four sides... However, the material is maximum 64" wide.... So, I am going to have a seem..... Do I sew the material together? I am not good at sewing.... Is there an easier way to do this? Thoughts?



I'm actually going to do the same thing, and I will have the same issue. My solution is actually to just sew it together. But I have sewing machine and a wife who knows her way around it.


Even so, you can sew it very easily with a basic sewing machine. I'd visit Joann's and see what they suggest in sewing it together. Heck, they might even suggest a small class they have for sewing where you could take the material in and sew it up that way.


----------



## Terry Montlick

Make sure you have any pattern or texture matched up when sewing Guilford fabric. It may not be obvious up close, but step back, and you can see it.


Regards,

Terry


----------



## Dennis Erskine

I haven't followed your interior design here; but, if you space your columns or just use pilasters (vertical trim) to be 65" or less, then no seams (no matter how hard you try, you'll see the seams).


----------



## will1383

I do know the seam that I will have will be located behind my AT screen, so it should be less of an issue in my specific case.


bty, Dennis, my Atlantic Technologies speakers arrive today.


----------



## harrisonbound




> Quote:
> Originally Posted by *will1383* /forum/post/15093476
> 
> 
> I'm actually going to do the same thing, and I will have the same issue. My solution is actually to just sew it together. But I have sewing machine and a wife who knows her way around it.
> 
> 
> Even so, you can sew it very easily with a basic sewing machine. I'd visit Joann's and see what they suggest in sewing it together. Heck, they might even suggest a small class they have for sewing where you could take the material in and sew it up that way.



I am not sure about the sewing.... I am a horrible sewer and would probably screw it up... How easy to make sure the two parts match up?


----------



## will1383




> Quote:
> Originally Posted by *harrisonbound* /forum/post/15093438
> 
> 
> My front wall is 80" tall and about 13 feet wide.... I covered it floor to ceiling with OC 703 and now want to cover it with GOM... So, what is the best way to do this... I have wood strips on all four sides... However, the material is maximum 64" wide.... So, I am going to have a seem..... Do I sew the material together? I am not good at sewing.... Is there an easier way to do this? Thoughts?





> Quote:
> Originally Posted by *harrisonbound* /forum/post/15109365
> 
> 
> I am not sure about the sewing.... I am a horrible sewer and would probably screw it up... How easy to make sure the two parts match up?



Depends on the material. If it is a basic, polyester weave, it's not too bad, you just have to make sure the grain is going the same way. If you are using a machine to sew that part, the most difficult thing to do is sew a straight line







.


you basically overlap the two pieces of material a very small amount, and pin it together. then you run it through the machine and literally run right through the pins (the timing of the machine allows you to basically miss them 98% of the time. Then you pull the pins out when you are done.


It's tedius, and the first time you use a machine is a bit alien, but it's not too bad, at least not for what this is. It's basically a straight line seam.


----------



## Terry Montlick

You could also just find a local seamstress (or seamster). There are lots of skilled people out there who do clothing alterations etc. part time.


- Terry


----------



## BIGmouthinDC

If you are using black GOM you never really see the seams unless you shine the front wall with a bright light.


Let's play find the seams:











Hint: the black is actually 4 panels sitting around the screen.


----------



## Dan Woodruff

Here are the seams I found in just a few seconds. I wouldn't count the lines at the bottom as seams because that is a step


----------



## will1383

Big mouth, that looks nice!


----------



## mobius




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15040942
> 
> 
> Multichannel music DVD's failed in the market for exactly the same reason ... every sound engineer had a different definition of what the proper playback space ought to be and the consumer wasn't about to pay a premium for a recording that might, or might not, sound good in his system. These "clowns", who believe they are smarter than we are have forgotten that it is you and I who are paying their salaries and they are close to being fired.
> 
> 
> End of rant (but if you're one of the "clowns" I haven't spoken with already, please feel free to contact me...I'll be more than happy to read the riot act to you directly).




You are exactly correct about multichannel music.


Their inability, or refusal to create an iron-clad standard which unified the medium doomed it from the start. Some mixes used the center channel, some did not. Some mixes gave instruments their own channel to play with...Like I want to hear a track with the guitar or drums mixed predominately in a surround channel- stupid.


I created a thread on AVS several years ago which complained about the degree to which AV reviewers use music to gauge audio components they've tested. My justification was the aforementioned hodgepodge of mixes.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *mobius* /forum/post/15116088
> 
> 
> I created a thread on AVS several years ago which complained about the degree to which AV reviewers use music to gauge audio components they've tested. My justification was the aforementioned hodgepodge of mixes.



Less of an issue with classical music than with studio-produced music.


----------



## pepar




> Quote:
> Originally Posted by *mobius* /forum/post/15116088
> 
> 
> You are exactly correct about multichannel music.
> 
> 
> Their inability, or refusal to create an iron-clad standard which unified the medium doomed it from the start.



Not sure I'd agree that that was what doomed it, or even if doomed is the correct term. DVD-A/SACD did certainly wither to virtually nothing. If a single format could have been agreed upon (a la CD), or if a single format had emerged victorious (VHS or BD), then perhaps hi-res multichannel music would have had more success.


Perhaps we will have it again with Blu-ray. There are concerts in 5.1, but the surrounds contain only ambiance and crowd noise. I *really* like studio mixes in multichannel, but with Blu-ray being an audio/*video* format, we may never get that. I am clinging to my DVD-A collection and am seriously considering buying my first SACDs in the form of the Genesis catalog.


> Quote:
> Some mixes used the center channel, some did not. Some mixes gave instruments their own channel to play with...Like I want to hear a track with the guitar or drums mixed predominately in a surround channel- stupid.



These, at least your latter comment, comes down to the aesthetics/artistic decision of the artist or, more lkely, the producer/engineer.


My comments are in re rock, jazz and pop, and with those I have no problem with a solo instrument in a surround speaker as long as the mix as a whole is more or less balanced. I would not want to listen to a jazz quartet with an instrument "per corner."


Anyway, just my $.02.


----------



## Pfdjr1

Pretty sure I know the answer to this question, but I'm gonna throw it out there anyway. Is there any way to turn a room with hardwood floors into dedicated HT without covering up the hardwood floors?? If so, how??


----------



## pepar




> Quote:
> Originally Posted by *Pfdjr1* /forum/post/15120196
> 
> 
> Pretty sure I know the answer to this question, but I'm gonna throw it out there anyway. Is there any way to turn a room with hardwood floors into dedicated HT without covering up the hardwood floors?? If so, how??



Generally, it is not a good idea to have parallel reflective surfaces. A throw rug, perhaps, or you could mount acoustical treatments on the ceiling. Beyond that in a room with all hard surfaces, you should research controlling reverberance. Most of us also recommend absorption at the first reflection points. There is not universal agreement on that though.


----------



## mobius




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15116966
> 
> 
> Less of an issue with classical music than with studio-produced music.




As I recall, you responded to the prior thread Kal. Hello again.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *mobius* /forum/post/15121361
> 
> 
> As I recall, you responded to the prior thread Kal. Hello again.



Hi. My point is that, if there is a standard for the balance and layout, even from a traditional musical score, it sets conventional limits on the inventiveness of the mixing/mastering.


----------



## nathan_h




> Quote:
> Originally Posted by *Pfdjr1* /forum/post/15120196
> 
> 
> Pretty sure I know the answer to this question, but I'm gonna throw it out there anyway. Is there any way to turn a room with hardwood floors into dedicated HT without covering up the hardwood floors?? If so, how??



"cover" the ceiling.


Depending on the shape/color, you could get panels that blend in OR ones that make an architectural statement.


----------



## srubenst

Does anybody know where I can purchase acoustically transparent fabric that looks like this? Or, any other place online where I can get some interesting, fancy, etc patters? I've run across a few but the samples they send me are very bland. They almost look like canvas.


I would like to use this fabric to cover places where the speakers will go, as well as for absorption panels that will go on the walls.


Thanks!


----------



## CruelInventions

Gilford of Maine (GOM) has a ton (by "ton" I mean dozens) of different patterned fabrics, some more acoustically transparent than others, but many of which would be acceptable for acoustic treatments, or at least, with minimal acoustical compromise. Most acoustical treatment companies stick with the most basic/bland GOM fabrics, but will often allow you to use one of the other many GOM fabrics if you request one (usually with an upcharge for the fabric).


Sorry, can't find my GOM related links right now.


----------



## AnthemAVM

Was wondering why Acoustic Sciences Corporation (ASC) doesn't get any talk in this thread?


----------



## krasmuzik

Because the owner does not participate here trolling for biz?


----------



## pepar




> Quote:
> Originally Posted by *krasmuzik* /forum/post/15147975
> 
> 
> Because the owner does not participate here trolling for biz?


----------



## CruelInventions

and with their insane mark-ups, they can afford to sell only a few per month and then sit back and gleefully count the cash between setting up tee times.


----------



## mobius




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15122366
> 
> 
> Hi. My point is that, if there is a standard for the balance and layout, even from a traditional musical score, it sets conventional limits on the inventiveness of the mixing/mastering.




I understand what you're saying, but I don't think establishing a standard would've eliminated creativity. At the very least, a _baseline_ of five-channels should've been specified for all multichannel mixes IMO. If an engineer wanted to get funky with his/her mix, then market the performance as a multi-disc set/special edition which includes the standard five-channel performance, stereo, and mixes with guitars flying around the back speakers.










Anyway, back to acoustic treatments discussion. We've (or I've) strayed off the subject, so I'll shut up.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/15122366
> 
> 
> Hi. My point is that, if there is a standard for the balance and layout, even from a traditional musical score, it sets conventional limits on the inventiveness of the mixing/mastering.





> Quote:
> Originally Posted by *mobius* /forum/post/15151529
> 
> 
> I understand what you're saying, but I don't think establishing a standard would've eliminated creativity. At the very least, a _baseline_ of five-channels should've been specified for all multichannel mixes IMO. If an engineer wanted to get funky with his/her mix, then market the performance as a multi-disc set/special edition which includes the standard five-channel performance, stereo, and mixes with guitars flying around the back speakers.



I should have put "inventiveness" in italics with a smiley.


----------



## Dennis Erskine

Picasso, DaVinci, VanGogh didn't seem to have their creativity (inventiveness) limited by sticking to canvas.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15154410
> 
> 
> Picasso, DaVinci, VanGogh didn't seem to have their creativity (inventiveness) limited by sticking to canvas.



Geniuses are excepted.


----------



## allredp




> Quote:
> Originally Posted by *mobius* /forum/post/15151529
> 
> 
> I understand what you're saying, but I don't think establishing a standard would've eliminated creativity. At the very least, a _baseline_ of five-channels should've been specified for all multichannel mixes IMO. If an engineer wanted to get funky with his/her mix, then market the performance as a multi-disc set/special edition which includes the standard five-channel performance, stereo, and mixes with guitars flying around the back speakers.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Anyway, back to acoustic treatments discussion. We've (or I've) strayed off the subject, so I'll shut up.



Good points mobius--and an even better one in your signature.


----------



## mike_wassell

How I Built Economical Acoustical Treatment Panels


I started looking into acoustical treatment several months ago. I decided I did not want to spend a lot of money on treatment and I would make it myself. I read every web site I could find on the subject. Originally I thought I would use Owens Corning 703 and 705 attached to a frame covered with burlap on the front only. I was going to use pieces of 1” x 1” screw to the back of the frame to hold the rigid fiberglass in place. I decided on doing bass traps and reflection point treatment. However for this post I mainly wanted to concentrate on the panels I made for the reflection points since they comprised the majority of what I made. I was thinking about diffusers in the back of my home theater but the more I read I decided that diffusion would not be as effective as absorption in my room due to its size and the proximity of the walls to the seating area. I have a relatively small HT room 13’ x 17’ x 8’.


I decided to let my fingers do the walking and called several local insulation companies to avoid shipping charges. Shipping on the insulation is very expensive. I found Owens Corning and Knauf locally cheaper than I could buy it on the net mainly due to savings on shipping costs. Then I one of the companies I called told me that they could get whatever I wanted (Owens Corning, Knauf, etc.) but that they had some IIG Sound Attenuating Fire Batt in stock that was left over from a previous job and they would sell it do me at a discounted price. So I picked up about 40 panels of 2’ x 4’ x 2” IIG MinWool Sound Attenuation Fire Batt Insulation at approximately $0.20 a SF that’s about $1.60 a panel. Calling locally really save me some big bucks on the insulation. I paid $1.60 for a panel of IIG MinWool as opposed to $15.00 for a panel OC 703. The sound attenuating propertied of these two items are practically identical and can be found on their web sites.


The first problem I encountered is the MinWool was very flexible and friable. I would think the more rigid stuff would be easier to work with. This material would definitely require a frame with a back. So I decided to use burlap for the back instead of the 1 x 1s. The 1 x 1s would never have worked with the MinWool because it is very flexible and friable. However I was not too crazy about the texture and color of the burlap so I decided to use acoustically transparent fabric from Acoustimac http://www.acoustimac.com/index.php?...tpage&Itemid=9 for the front of the panels. The fabric is about $9.00 a yard however it is 60-64” wide. This material has a great texture is stretchable and comes in a nice variety of colors. I spend a little extra on the fabric because a yard of 60” burlap can be bought for about $2.00. Then on the other hand a yard of Guilford of Maine fabric costs at least $15.00 a yard.


For the frame I use 1” x 4” x 8’ pine stripping. This is the lowest grade of pine that can be found it was $1.65 for an 8’ board. I had to inspect every board carefully before I bought it because most of them are bowed, warped, or damaged. However after weeding through the boards I was able to find enough good boards to make all of the frames for my panels. I had much better luck finding good boards at Home Depot as opposed to Lowes.


It cost me about $15.00 to make a 2’ x4’ acoustical treatment panel. I treated about 30% of my room’s surface area not counting the floor. This includes bass traps that were placed in the corners. I made approximately 30 panels. I could have made them a lot cheaper if I would have used burlap to cover both the front and back of the panels. In that case they would have been approximately $7.50 a panel. However the panels I made turned out real nice. The main reason they were so cheap is because I was flexible on the type of insulation, wood, and fabric I used and called around to get the best price. Most of this type of insulation (rigid fiberglass, mineral wool and rock wool) has very similar acoustical properties. The acoustical properties for the individual products can usually be found on the manufactures web site.


----------



## citizen arcane

Has anyone built or had any experience w/ these DIY tube traps?

http://web.archive.org/web/200702080...m/tubetrap.htm 


They look very interesting for broadband absorption.


----------



## Ethan Winer

Those satisfy the basic requirement of getting absorption into the room, but they're not large enough for great results at low frequencies. Typical 2x4 foot panels, 4 inches thick are known to work well. Flat panels are also easier to make.


--Ethan


----------



## citizen arcane

Thanks for the reply Ethan, knowing they're acceptable by your standards helps and I will incorporate them in my media room. For lows I got a great buy on 6" Auralex Sonocolumns (which haven't been mentioned here much) enough to do floor to ceiling on all four vertical corners and will add two 2x4x4 inch panels to a wall as well.


----------



## cuzed2

Ethan (All),


I understand the limitations for deep base with these unique 1/2 round "traps".


However:


In my case I have treated all 4 corners of my room, floor to ceiling with 17" x 17" x 24" cornertraps. My problem is a reflective back wall.


I wonder if making an alternating and staggered pattern of these (10" length x by 10" wide, might make an effective diffusor panel for a back wall, (with the added bonus of some absorption..???


Comments?






> Quote:
> Originally Posted by *citizen arcane* /forum/post/15175849
> 
> 
> Thanks for the reply Ethan, knowing they're acceptable by your standards helps and I will incorporate them in my media room. For lows I got a great buy on 6" Auralex Sonocolumns (which haven't been mentioned here much) enough to do floor to ceiling on all four vertical corners and will add two 2x4x4 inch panels to a wall as well.


----------



## reece

Hi all,

I have a question regarding treating the sidewalls of my theater. I have done the corner bass traps ( 5" cotton ), the entire front wall, and the first reflection points (703c fiberglass). All floor to ceiling. I need to treat the sidewalls, but do I build 2x4 panels or do I go floor to ear level and nothing above that? In either case I will be using the 703 fiberglass. I will be covering them with GOM.

I dont have a rear wall to my theater. I left it open so that we can see the screen from the rear bar area which is about 17' feet behind the theater.


Thank you very much.

Here are a couple of pictures:


----------



## SteveMo




> Quote:
> Originally Posted by *reece* /forum/post/15180325
> 
> 
> Hi all,
> 
> I have a question regarding treating the sidewalls of my theater. I have done the corner bass traps ( 5" cotton ), the entire front wall, and the first reflection points (703c fiberglass). All floor to ceiling. I need to treat the sidewalls, but do I build 2x4 panels or do I go floor to ear level and nothing above that? In either case I will be using the 703 fiberglass. I will be covering them with GOM.
> 
> I dont have a rear wall to my theater. I left it open so that we can see the screen from the rear bar area which is about 17' feet behind the theater.
> 
> 
> Thank you very much.
> 
> Here are a couple of pictures:



Floor to ear level. Covering the entire walls will usually not sound right in small room acoustics.


----------



## reece

I only did the front wall, corner bass traps, and first reflection point floor to ceiling. My sidewalls will not be floor to ceiling. I am referring to the area between the columns. My room is 16' wide and 17' long( rear row ).

The second picture shows the back of the room.


Thanks


----------



## will1383




> Quote:
> Originally Posted by *reece* /forum/post/15180325
> 
> 
> Hi all,
> 
> I have a question regarding treating the sidewalls of my theater. I have done the corner bass traps ( 5" cotton ), the entire front wall, and the first reflection points (703c fiberglass). All floor to ceiling. I need to treat the sidewalls, but do I build 2x4 panels or do I go floor to ear level and nothing above that? In either case I will be using the 703 fiberglass. I will be covering them with GOM.
> 
> I dont have a rear wall to my theater. I left it open so that we can see the screen from the rear bar area which is about 17' feet behind the theater.
> 
> 
> Thank you very much.
> 
> Here are a couple of pictures:



I'd make sure that what you are hearing in the room is not what you are looking for before going down the road of additional absorbtion materials because it sounds like you already have alot in the room.


But, if you do feel you need to add additional treatments on the side walls, do not go any higher than the listener's ear level. From that point up, hit the early reflection points (which it seems like you already have).


----------



## Ethan Winer




> Quote:
> Originally Posted by *reece* /forum/post/15180325
> 
> 
> do I build 2x4 panels or do I go floor to ear level and nothing above that?



My preference is to have absorber panels _centered_ at ear height. Absorption much lower or much higher will not affect those reflections, but will affect overall ambience in the room which you may or may not need. Understand that sound from loudspeakers radiates outward - it's not a laser thin beam. So you want to treat at least a foot or two above and below ear level.


--Ethan


----------



## reece




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15186769
> 
> 
> My preference is to have absorber panels _centered_ at ear height. Absorption much lower or much higher will not affect those reflections, but will affect overall ambience in the room which you may or may not need. Understand that sound from loudspeakers radiates outward - it's not a laser thin beam. So you want to treat at least a foot or two above and below ear level.
> 
> 
> --Ethan



Thanks guys,


So putting 2 panels of 2x4 on each side should do the trick? Placing them about 1' above the ground?


Thanks again.


----------



## JimmyLeggs

Anyone know where I can purchase Owen Corning's SelectSound® Black Acoustic Boards? I'm in Montreal Quebec Canada. Owens Corning has been no help at locating a dealer for me or providing me with a product number I can try at Home Depot. Home Depot has no idea what I'm talking about either. Any help would be greatly appreciated. What's the going rate per sq ft?


----------



## pepar




> Quote:
> Originally Posted by *JimmyLeggs* /forum/post/15187920
> 
> 
> Anyone know where I can purchase Owen Corning's SelectSound® Black Acoustic Boards? I'm in Montreal Quebec Canada. Owens Corning has been no help at locating a dealer for me or providing me with a product number I can try at Home Depot. Home Depot has no idea what I'm talking about either. Any help would be greatly appreciated. What's the going rate per sq ft?



You will need to contact an HVAC distributor. (HVAC = heating, ventilation, air conditioning) Basically, the raw materials used in ABSORPTION are from the commercial construction world, and it is there where the prices are the lowest. Once the word "acoustical" becomes involved, the pricing goes up.


----------



## Ethan Winer




> Quote:
> Originally Posted by *reece* /forum/post/15187872
> 
> 
> So putting 2 panels of 2x4 on each side should do the trick? Placing them about 1' above the ground?



Yes.


----------



## velvet396

I have a massive "sound leak" problem in that I live in a small apartment and the sound from my living room is often just as loud in the next room (kitchen), which also continues to the bedroom. The problem is that while there is a wall between the kitchen and living room, there's just an open doorway and the kitchen floor is all tile.


I don't think WAF will let me hang treatments in the living room. What I was hoping to do was to build something that I could place in the doorway to block the sound (like when the wife goes to bed and I'm still up watching a movie or playing Gears of War 2).


I've done some basic research on acoustic damping but I'm not finding what I'm looking for... let alone knowing that I'm looking for the right item.


What do you, oh esteemed experts, suggest?


Room diagram:

_________TV & LCR spk's______

l

O

P

E

N

l

l

l

l

l

l

l___________i--fire--i__________


pretend the right wall is there... it has two windows with just blinds so I was hoping curtains would help


EDIT: my diagram failed. redid it just so you know where the open doorway is.


----------



## Weasel9992




> Quote:
> Originally Posted by *velvet396* /forum/post/15198554
> 
> 
> What I was hoping to do was to build something that I could place in the doorway to block the sound (like when the wife goes to bed and I'm still up watching a movie or playing Gears of War 2).



I think you already know the answer...it's not going to work real well. You might get some transmission loss up in the high mids and highs, but it'll leak like a sieve where low end is concerned. You'd have to build something far too massive to be portable in order to be useful for low end TL.


Frank


----------



## Terry Montlick




> Quote:
> Originally Posted by *velvet396* /forum/post/15198554
> 
> 
> ...
> 
> What I was hoping to do was to build something that I could place in the doorway to block the sound (like when the wife goes to bed and I'm still up watching a movie or playing Gears of War 2).



That would be a "door."









And a heavy, well-sealed one.


----------



## CruelInventions

I see wireless headphones in your future. Unfortunately, as already suggested, there's just no easy or quick or reasonable cost way around it.


----------



## pepar




> Quote:
> Originally Posted by *CruelInventions* /forum/post/15199437
> 
> 
> I see wireless headphones in your future. Unfortunately, as already suggested, there's just no easy or quick or reasonable cost way around it.



And maybe strap a Buttkicker on his . . .butt for the full range of sound.


----------



## velvet396




> Quote:
> Originally Posted by *Weasel9992* /forum/post/15198687
> 
> 
> I think you already know the answer...it's not going to work real well. You might get some transmission loss up in the high mids and highs, but it'll leak like a sieve where low end is concerned. You'd have to build something far too massive to be portable in order to be useful for low end TL.
> 
> 
> Frank



Fortunately the bass doesn't seem to travel, it's the highs and mids. Explosions and voices.


And it's a leased apartment, I can't build/add a door.


----------



## reece




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15188420
> 
> 
> Yes.



Thank Ethan.


----------



## yngdiego




> Quote:
> Originally Posted by *velvet396* /forum/post/15198554
> 
> 
> I don't think WAF will let me hang treatments in the living room.



Get rid of the WAF and put up good treatments.


----------



## velvet396




> Quote:
> Originally Posted by *yngdiego* /forum/post/15211986
> 
> 
> Get rid of the WAF and put up good treatments.



I'll keep the wife and I guess figure out how to put up a sound barrier type thing on my own. Anything is better than nothing. Maybe we have some foam insulation I can cover with fabric...


----------



## SteveMo




> Quote:
> Originally Posted by *velvet396* /forum/post/15214012
> 
> 
> I'll keep the wife and I guess figure out how to put up a sound barrier type thing on my own. Anything is better than nothing. Maybe we have some foam insulation I can cover with fabric...



I am surprised nobody has mentioned Sonic Print Acoustic panels by auralex. I have heard these have pretty high WAF. Maybe I am missing something.


----------



## pepar




> Quote:
> Originally Posted by *SteveMo* /forum/post/15214163
> 
> 
> I am surprised nobody has mentioned Sonic Print Acoustic panels by auralex. I have heard these have pretty high WAF. Maybe I am missing something.



I've seen some here ding them for their prices . . .


----------



## Ethan Winer

The problem with acoustic panels isn't so much the appearance of each one, but the fact that they need to be large and you need a lot of them. So even if each is a fabulous work of art, by the time you treat a room sufficiently the panels still dominate.


--Ethan


----------



## petee_c

I've got a 20x25'x94" size HT/Media/Games room. It's almost finished. My main seating area is about 12' back from a 120" screen. The front mains are on either side of the 9' screen.


I was listening to a new sub and speakers the last couple of nights, and the sound is horrible. It's way too bright. (Having 4 DD/GG walls, DD/GG Ceiling and concrete floor and a lone folding lounge chair as furniture will do that.)


Tonight, I'm hoping the sound will get better. We are adding 450sq ft of shag carpet and 8lb (the good stuff) underlay to cover the concrete floor. I may even move in a couch tonight.


I've called around locally, and a building supply place has Roxul Rockboard 40 (rigid mineral wool) instock for about $50Cdn for 80sq ft. This is the 2" thickness. The Rockboard 60 is not available at this time, and the Roxul factory is way behind on orders.


I want to frame it with 0.75x2" pine, and cover it with appropriate fabric.


I want to use it to cover the primary reflective spots on the side walls. Looking at BasementBob's numbers, I believe 2" Rockboard 40 has similar coefficients to other DIY materials.


My speed reading on the subject of basic acoustics is:


1. use mirrors to determine 1st reflectance points of your speakers. Do so at ear level of the seated position.


2. Place sound absorbers at 1st reflectance positions (centered at ear level)


3. Consider treating behind the speakers?


4. Consider corner bass traps.


Is the orientation (vertical/horizontal) of 1st reflectance sound absorbers important? I am thinking horizontally placed (2x4') absorbers would look better in my room (i.e under wall sconces) It may also mean I can use less of them.


The other option is to use some of the rockboard 40 and make 2x2' size panels.....


----------



## akakillroy

From my experiance:


> Quote:
> Originally Posted by *petee_c* /forum/post/15216299
> 
> 
> 1. use mirrors to determine 1st reflectance points of your speakers. Do so at ear level of the seated position.



Correct, but you might want to do it from EACH seat you have in the room. You may have to treat more than one location for each reflection point.



> Quote:
> Originally Posted by *petee_c* /forum/post/15216299
> 
> 
> 2. Place sound absorbers at 1st reflectance positions (centered at ear level)



See above



> Quote:
> Originally Posted by *petee_c* /forum/post/15216299
> 
> 
> 3. Consider treating behind the speakers?



Yes, if you are doing a dedicated room, then for sure as well as the front/screen wall.



> Quote:
> Originally Posted by *petee_c* /forum/post/15216299
> 
> 
> 4. Consider corner bass traps.



Defiantly



> Quote:
> Originally Posted by *petee_c* /forum/post/15216299
> 
> 
> Is the orientation (vertical/horizontal) of 1st reflectance sound absorbers important? I am thinking horizontally placed (2x4') absorbers would look better in my room (i.e under wall sconces) It may also mean I can use less of them.



See the first response, place them where they will cover the most area for the reflected source. Remember sound "cones" out from the speaker so the farther away the speaker is from the reflection point the wider the area of the reflection point.



> Quote:
> Originally Posted by *petee_c* /forum/post/15216299
> 
> 
> The other option is to use some of the rockboard 40 and make 2x2' size panels.....



Oh don't do that, get some OC703 in 1" or 2" and cover with GOM or equivalent for the best sound absorption.


You did good researching though, and I have been at it for about 6 months.


----------



## akakillroy

I am working on my acoustical panels and I picked up some 1/2 Berch hardwood plywood at Home depot and there was a guy there who was kind enough to rip it up into 2" strips (Saved me a lot of effort and time). I have all my pieces cut but I am not sure yet if I want to bevel or round the edges before covering them in GOM.


What have others done?


If I do bevel the edges, I though about doing each board before I assembled them but the corners would be messed up, so I suppose I will have to assemble them then cut them on the table saw or bench router.


Next I am covering them with Deep Burgundy GOM (Thanks bpape!). I tested the fabric over the OC703 and I can't see any color bleeding through, but when its pulled tight I can see some of the "light" of the wood showing through the fabric. Would you paint the wood a similar color of the fabric before you covered the panels or you think from any distance I will not see it.


Thanks!


----------



## petee_c




> Quote:
> Originally Posted by *akakillroy* /forum/post/15217066
> 
> 
> 
> Oh don't do that, get some OC703 in 1" or 2" and cover with GOM or equivalent for the best sound absorption.
> 
> 
> You did good researching though, and I have been at it for about 6 months.



Thanks for the reply


re: Rockboard 40 vs 2" OC703


703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00


RXL 40 2" (51mm) 4.0 pcf (64 kg/m3) 0.26 0.68 1.12 1.10 1.03 1.04 1.00


The Roxul Rockboard 40 has almost the same numbers as the OC703..... OC703 is hard to get /expensive in my area....


P


----------



## giomania

I read this entire thread from start to finish. I printed it off and read it on the train over the course of about six weeks. I highlighted and saved the pages with good information on it, and wound up with a 3/4" thick bundle of papers.


So, now I am armed (with information) and dangerous. But I do have one question after all this...what do I win? A set of FRP absorbers?


Seriously, I hope to start my acoustical treatment project in January.


Mark


----------



## akakillroy




> Quote:
> Originally Posted by *giomania* /forum/post/15217856
> 
> 
> I read this entire thread from start to finish. I printed it off and read it on the train over the course of about six weeks. I highlighted and saved the pages with good information on it, and wound up with a 3/4" thick bundle of papers.
> 
> 
> So, now I am armed (with information) and dangerous. But I do have one question after all this...what do I win? A set of FRP absorbers?
> 
> 
> Seriously, I hope to start my acoustical treatment project in January.
> 
> 
> Mark



You win the knowledge that you worked so hard to obtain. Well done congratulations! ;-)


----------



## Frank D




> Quote:
> Originally Posted by *petee_c* /forum/post/15217581
> 
> 
> Thanks for the reply
> 
> 
> re: Rockboard 40 vs 2" OC703
> 
> 
> 703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00
> 
> 
> RXL 40 2" (51mm) 4.0 pcf (64 kg/m3) 0.26 0.68 1.12 1.10 1.03 1.04 1.00
> 
> 
> The Roxul Rockboard 40 has almost the same numbers as the OC703..... OC703 is hard to get /expensive in my area....
> 
> 
> P





Have you considered using Linacoustic RC? Sold in a 1" thick in a roll. Cost is about $165 Cdn. You can buy it at Glass Cell in Etobicoke ph# 416 241-8663(for a charge they deliver too).


They also sell rigid fibreglass. They come in 2" thick 4x8 sheets are OFI 48 from Ottawa fibre.


----------



## mobius




> Quote:
> Originally Posted by *pepar* /forum/post/15187968
> 
> 
> Once the word "acoustical" becomes involved, the pricing goes up.




:LOL


Good point.


----------



## mobius




> Quote:
> Originally Posted by *giomania* /forum/post/15217856
> 
> 
> I read this entire thread from start to finish. I printed it off and read it on the train over the course of about six weeks. I highlighted and saved the pages with good information on it, and wound up with a 3/4" thick bundle of papers.
> 
> 
> So, now I am armed (with information) and dangerous. But I do have one question after all this...what do I win? A set of FRP absorbers?
> 
> 
> Seriously, I hope to start my acoustical treatment project in January.
> 
> 
> Mark





If you want to feel even more inadequate, by F. Alton Everest's Master Handbook of Acoustics.

http://www.mhprofessional.com/produc...sbn=0071360972 


It's not that bad really. Lots of equations and stuff.







Seriously though, it offers a good primer on acoustics. I wouldn't have known about it had I not read this thread. This thread offers more practical recommendations for the average home though.


----------



## mobius




> Quote:
> Originally Posted by *akakillroy* /forum/post/15217131
> 
> 
> I am working on my acoustical panels and I picked up some 1/2 Berch hardwood plywood at Home depot and there was a guy there who was kind enough to rip it up into 2" strips (Saved me a lot of effort and time). I have all my pieces cut but I am not sure yet if I want to bevel or round the edges before covering them in GOM.
> 
> 
> What have others done?
> 
> 
> If I do bevel the edges, I though about doing each board before I assembled them but the corners would be messed up, so I suppose I will have to assemble them then cut them on the table saw or bench router.
> 
> 
> Next I am covering them with Deep Burgundy GOM (Thanks bpape!). I tested the fabric over the OC703 and I can't see any color bleeding through, but when its pulled tight I can see some of the "light" of the wood showing through the fabric. Would you paint the wood a similar color of the fabric before you covered the panels or you think from any distance I will not see it.
> 
> 
> Thanks!




From what you're describing, it sounds like it may be easier to miter the edges (I assume you're only talking about the plywood) after assembly on the table saw. To prevent the wood from showing you could paint it burgandy or flat black most likely.


----------



## petee_c




> Quote:
> Originally Posted by *Frank D* /forum/post/15218674
> 
> 
> Have you considered using Linacoustic RC? Sold in a 1" thick in a roll. Cost is about $165 Cdn. You can buy it at Glass Cell in Etobicoke ph# 416 241-8663(for a charge they deliver too).
> 
> 
> They also sell rigid fibreglass. They come in 2" thick 4x8 sheets are OFI 48 from Ottawa fibre.




Hi Frank,


That Linacoustic RC has the same coefficient numbers as the other 2 products I mentioned.....


Looking at some websites... 80ft2 of panelling should be enough to treat my room. I can get 80ft2 for $50cdn locally.


----------



## ScruffyHT

petee_c ... Are you planning to treat the whole wall behind the screen ? ... it has been recommended here that for home theater the screen wall should be as dead as possible ... if you decide to do this then that would be 160 sq ft right there


----------



## petee_c

Hi Scruffy,


I hadn't really planned on treating the whole screen wall. My screen is 5x9' (120") BOC.


I was originally going to do (assuming 2x4' panels)


2 panels front wall (behind LR mains)

2 panels Left side wall (1st mirror reflection from LCR)

2 panels Right side wall (1st mirror reflection from LCR)


The carpet was installed last night, and we moved in an old couch into the room. Both seem to have helped the sound a bit.


--------------------------------------------------------------------

I've got another idea for sound absorbers.


I've got some left over S&S insulation. (15.25"x48"x3"). I'm thinking about making pillows out of it and seeing if that helps.


The plan I dreamt up this morning is to go to the fabric store and get suitable material to make the covers out of it, and sew a basic pillow case a little larger than the surface area of each S&S batt.


1. I am thinking along the lines of a pillow case about 17"x 52" finished size.


2. Cut out 2 cardboard pieces, each 15.25x48".


3. Sandwich 1 batt of S&S insulation between the 2 sheets of cardboard.


4. Compress the cardboard/S&S sandwich enough so it will slide into the 'pillow case'


5. Slide cardboard/S&S/cardboard sandwich into the pillowcase.


6. Slide out the topsheet of cardboard, and fold over and sew the open end of the pillow case.


I'm hoping this gives me an adequate temporary sound absorbing panel. The backlayer of cardboard should help the S&S batt maintain it's shape, and the pillow case should help the S&S from falling apart.


P


----------



## Webb

I made a seperate thread but perhaps this is better posted here.


I am aware that there should be a minimum seating distance when using diffusion to avoid phase artifacts. However I believe that the distance is based upon 3 times the lowest frequency being diffused.


So say I build a diffuser that goes down to 300 Hz which would be 3.75 feet in terms of wave length, multiplied by three I get a minimum 11.25 feet seating distance not doable for me.


However If I build my diffuser to tackle say 600 Hz (596 HZ) I would have to only sit 5.62 feet away from it which is totally doable.


If I designed it with a well width of .5, a 6 ½ depth and 7 wells per period I could diffuse 596 - 13560 Hz which covers a decent range.


Assuming that it is three times the lowest wave length and my seating distance is correct, does the frequency range look good enough? I would add absorption for the lower frequencies to help with those of course


I have heard a room with diffusion and really enjoy what it can do so this would be great to have.


Any thoughts????????????


----------



## bdubs1

Lots of info in this thread to be digested. I plan to do the chunk corner traps in all corners, and first reflection points to start. Do first reflection point pannels made form 703 have to be spaced away from the wall, or can the fiberglass go right aginst the wall? I think I read that it is better to be spaced, but I dont want the pannel sticking to far out form the wall.


----------



## akakillroy




> Quote:
> Originally Posted by *bdubs1* /forum/post/15227218
> 
> 
> Lots of info in this thread to be digested. I plan to do the chunk corner traps in all corners, and first reflection points to start. Do first reflection point pannels made form 703 have to be spaced away from the wall, or can the fiberglass go right aginst the wall? I think I read that it is better to be spaced, but I dont want the pannel sticking to far out form the wall.



Against the wall is fine, the gap give a little better performance out of the absorption panel but I agree they stick too far away from the wall if you add the gap. I am going to use 2" 703 in a wood frame covered in GOM and I will place some small felt pads on the back that will give it a little bit of a gap but not enough to matter.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Webb* /forum/post/15226093
> 
> 
> I made a seperate thread but perhaps this is better posted here.



Actually, a separate thread is better. This dinosaur should be allowed to die.











> Quote:
> does the frequency range look good enough? I would add absorption for the lower frequencies to help with those of course



Yes, and yes on needing absorption for lower frequencies.


--Ethan


----------



## mave198

Hello everyone.


Just wanted some input on what I plan to do in my living room. By the way, it's a leased apt so changing the dimensions is not a option.


Plan to add about 6 acoustic panels to my living room which is 16x11x10. along the side walls. Have pretty thick carpet and have black out suede curtains covering my 2 windows and living room entrance which I close when I game or watch movies. (Are blackout curtains recommended, or should I opt for something like regular suede curtains that don't have the extra lining?)



With that said, when I clap my hands I still have a pretty back echo and I know it's killing my 5.1 setup.


With regard to the panels, should I place 2 panels on each wall between my sitting area and the TV that are 2 inches thick and place 1 panel behind me on each wall that is 4 inches thick for better bass response?


My sub is in the front right hand corner of my living room.


Or is my plan overkill??


Thanks for any advice and responses.


----------



## R Harkness

*ACOUSTIC BASS TRAP MATERIAL RECOMENDATION?*


Folks,


I'm doing a home theater reno in my living room. In testing with my L/C/R speakers hooked up to a Denon receiver I've decided the sound is actually pretty good and I'm not going to go to "heroic" measures in terms of putting acoustic treatment everywhere. The main issue is some "bass lift" (re-inforced bass, a bit bloated) due to the speakers being close to the screen and room corners.


A while back I paid an acoustician for consultation. He suggested I could add a sort of bass trapping idea along the bottom and top of the screen. His services are pretty expensive to do the work so I'm looking at perhaps having my main contractor do it. So I'm looking for recommendations of what material would do the best job and where to buy it.


Here is a GoogleSketchup of the screen wall. The two bright blue areas above and below the screen would be the bass trap material.


The bottom trap would be 9 1/2 inches tall and 7 inches deep from the wall.

The top is about 14 inches tall, about 10 inches deep from the wall.


What do people recommend here, and would this in fact be effective at all as acoustic treatment for the issue I'm having? Thanks.


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/15351050
> 
> *ACOUSTIC BASS TRAP MATERIAL RECOMENDATION?*
> 
> 
> Folks,
> 
> 
> I'm doing a home theater reno in my living room. In testing with my L/C/R speakers hooked up to a Denon receiver I've decided the sound is actually pretty good and I'm not going to go to "heroic" measures in terms of putting acoustic treatment everywhere. The main issue is some "bass lift" (re-inforced bass, a bit bloated) due to the speakers being close to the screen and room corners.
> 
> 
> A while back I paid an acoustician for consultation. He suggested I could add a sort of bass trapping idea along the bottom and top of the screen. His services are pretty expensive to do the work so I'm looking at perhaps having my main contractor do it. So I'm looking for recommendations of what material would do the best job and where to buy it.
> 
> 
> Here is a GoogleSketchup of the screen wall. The two bright blue areas above and below the screen would be the bass trap material.
> 
> 
> The bottom trap would be 9 1/2 inches tall and 7 inches deep from the wall.
> 
> The top is about 14 inches tall, about 10 inches deep from the wall.
> 
> 
> What do people recommend here, and would this in fact be effective at all as acoustic treatment for the issue I'm having? Thanks.



If they are the only traps in the room, I would also do the sides up front as well. The bottom one is a bit on the smallish side. If you go to my site linked in my sig you will see that I've done the top and two sides up front. It helped GREATLY, but I am going to add the SSC traps to the ceiling/back wall juncture, the right rear wall/wall corner and part way along the left wall/ceiling as well.


Just my $.02 that your room will benefit from more trapping than what you've indicated.


----------



## R Harkness

I appreciate your reply Pepar.


Does anyone know which type of acoustic material I should use for the top bottom portions (obviously it will have to be able to be cut/formed to the proper dimensions) and where to get it?


Thanks.


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/15361182
> 
> 
> I appreciate your reply Pepar.
> 
> 
> Does anyone know which type of acoustic material I should use for the top bottom portions (obviously it will have to be able to be cut/formed to the proper dimensions) and where to get it?
> 
> 
> Thanks.



Many use Owens Corning 703 sold by HVAC distributors. Not sure where to get it in GTO. If you want to cross the 703 to other products, go here , find the 2" 703 and look for comparable products.


----------



## Frank D




> Quote:
> Originally Posted by *r harkness* /forum/post/15361182
> 
> 
> i appreciate your reply pepar.
> 
> 
> Does anyone know which type of acoustic material i should use for the top bottom portions (obviously it will have to be able to be cut/formed to the proper dimensions) and where to get it?
> 
> 
> Thanks.



ofi 48 (3 lbs density like 703) or ofi 72 (4 lbs density like 705). The ofi 48 should be fine for you. Go to glass cell in etobicoke. You want it non-faced (it is cheaper too).


----------



## Weasel9992




> Quote:
> Originally Posted by *Frank D* /forum/post/15362485
> 
> 
> ofi 48 (3 lbs density like 703) or ofi 72 (4 lbs density like 705). The ofi 48 should be fine for you. Go to glass cell in etobicoke. You want it non-faced (it is cheaper too).



That's the right answer. It's also easy to shape, so no worries there.


Frank


----------



## R Harkness

Thanks a million for the answers.


I checked Glass Cell and it looks like were I'll get the material.


This will certainly be cheaper than having the acoustician do all the work!


----------



## GoCaboNow

Another alternative product question. Long story short, I ended up with a bunch of sheets of Temple Inland "sound choice" sound deadening fiber boards. http://www.templeinland.com/Building...d/SoundChoice/ 


So instead of doing a double drywall treatment for my ceiling I used these as a first layer in finishing my ceiling and underside of soffits. This is a single basement room that is 13' x 23' x 9' and will be a dedicated HT. The room will then be finished in drywall OVER the sound board. (next week?) Since I have a bunch of these boards left over I am wondering what kind of performance they would do as accoustical treatments if I wrapped them in GOM and used on the wall as first reflecting point or cut up and used in Bass traps? They are a pressed fiber board but I am not sure how they would compare to typical wall treatment or OC703 for the traps.


I have enough left over that I could line the screen wall and entire sides of the room IF it makes sense. Kind of a weird question, but any thoughts are appreciated.


----------



## rutlian

I've been reading this thread on and off for a few days now and it is very informational and a lot of experts are in here. and I am no expert when it comes to acoustics treatment. However I am building an acoustic panel my room is 13ft wide, 18feet long and 7.5 high, I am planning to put bass trap in front wall corners but not for now anyway for this time I have a budget for 6 2'x4'x2'' panel board and I plan to used them in this. and this are all be hang 1 ft from the floor.


1 panel board behind my each main speakers

3 panel board for the left wall (for the first reflection point)

1 panel board for the right wall, it will be closer to the right corner with about 1 foot space between panels behind my right main speaker (I have 3 windows in my right wall with thick curtains covering all 3 windows.

2 2x4x2 right behind the seating area (2nd row seat) I plan to put these 2 panel on each side of my back sorrounds.


are my panel placement okey for now?

thanks any advise is welcome and again I am a newbie when it comes to acoustic treatment. thank you all for the advise.


I know my panels are not much but this is only a starter for me, I plan to put bass traps in 3 corners in a future like 2'x4'x4" from the floor up in the corners, having stock up like some other members is way to much for my budget.


----------



## SteveMo

Getting 6 2" panels could be a mistake. They might work well for treating some spot areas but this is light absorption when you consider 2". 2" panels work down to about 500Hz where as 3" or 4" will work down to around 300Hz. Spacing them away from the wall would also help if possible.


I have 2" panels at my first reflection points. I ended up spreading them out and they will need to have thicker panels placed over them later.


----------



## rutlian

stevemo Thanks,


when you said you ended up spreading your 2" panel like how far apart are they, so it is not good to place them together for atleast 2' apart to each other? I wished I can still

return them. I already placed 1 from each behind my main speakers and 1 in the right wall where my windows are, that's only 3 panel yet but honestly I could hear the difference between not having acoustic panel even my wife noticed it, before I have to crank up my Onkyo 705 now I don't have to, honestly it improved, The bass, two main speakers are more details now I can hear better background while my center is in action,

that is why I would like to get more information about the acoustic panel, I am really impressed eventhough I know I need more panel to build. I might just get the 4" panel then for bass trap it will be standing in the corners and for the ceiling just above my screen (ala pepar style). Thanks for the advised everyone I appreciate it.


----------



## rutlian




> Quote:
> Originally Posted by *SteveMo* /forum/post/15368738
> 
> 
> Getting 6 2" panels could be a mistake. They might work well for treating some spot areas but this is light absorption when you consider 2". 2" panels work down to about 500Hz where as 3" or 4" will work down to around 300Hz. Spacing them away from the wall would also help if possible.
> 
> 
> I have 2" panels at my first reflection points. I ended up spreading them out and they will need to have thicker panels placed over them later.



as I read more and more on this thread and I am now on page 112 it was mentioned on page 112 that 1" thick is good enough to treat the first

reflection point, I am confused and you are saying that 2" might be a mistake?

I am hoping 2" is good enough for my first reflection point.


----------



## ExToker

Happy Holidays to you all,

I'd like opinions on the best approach to a wall 'project'. I have a HT with one very live Side wall (studs and 1/2" drywall). This is in a basement and all the other walls were built with acoustics in mind. (block/foamboard/batt insulation/drywall)

I'm beginning to explore room treatment but this wall obviously gets first attention since its pretty much a 8' x 13' drum.

Adjoining on the back side is a large utility room, in which the wall is open and pretty much a clean palette. I can beef it up by doubling studs/horizontal bracing etc. to stabilize it structurally.

My question is ways to approach LFE treatment though. Should I treat the inside of the wall or would I be just as well off using batt insulation for the HF and using the adjoining utility room as kind of a giant bass trap?

I know corner traps will be needed also but just trying to make something good out of a bad, if possible.


----------



## SteveMo




> Quote:
> Originally Posted by *rutlian* /forum/post/15370986
> 
> 
> as I read more and more on this thread and I am now on page 112 it was mentioned on page 112 that 1" thick is good enough to treat the first
> 
> reflection point, I am confused and you are saying that 2" might be a mistake?
> 
> I am hoping 2" is good enough for my first reflection point.



1" is useless. You would be as well off hanging drapes on the wall. I'm saying that it could be, not that it will be. 2" is good, but 3" is better.


----------



## rutlian




> Quote:
> Originally Posted by *SteveMo* /forum/post/15371068
> 
> 
> 1" is useless. You would be as well off hanging drapes on the wall. I'm saying that it could be, not that it will be. 2" is good, but 3" is better.



Thanks I would stick with 2" then


----------



## SteveMo




> Quote:
> Originally Posted by *rutlian* /forum/post/15371076
> 
> 
> Thanks I would stick with 2" then



Your welcome


----------



## Dennis Erskine

Actually, 1" is not useless. Whether or not 1", 2" or 100" is required depends on a long list of factors. Among these are:


1. Reverberation decay times ought to be pretty much consistent throughout the frequency spectrum so you need to consider the impact on the entire space;

2. Too much absorption is not a good thing;;

3. While many just look at the absorption of the panel on the wall, you also must consider the absorption characteristics of the material behind the panel (this is where almost all 'panel plans' go south and you're actually getting absorption at frequencies below what you'd expect the panel to provide);

4. The more you absorb at the early reflection points, the more you run the risk of decreasing the width of the sound stage;

5. The near field and off axis response of the speakers must be considered before you execute a plan of hanging fuzz on the walls ... diffusion may be the better choice.

6. Also, at the early reflection points, you will not be achieving as much HF absorption as you may think due to the oblique angle of incidence from front speakers.


----------



## SteveMo




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15371148
> 
> 
> Actually, 1" is not useless. Whether or not 1", 2" or 100" is required depends on a long list of factors. Among these are:
> 
> 
> 1. Reverberation decay times ought to be pretty much consistent throughout the frequency spectrum so you need to consider the impact on the entire space;



Does not look very even in my left seat. Thoughts?












> Quote:
> 2. Too much absorption is not a good thing;;
> 
> 3. While many just look at the absorption of the panel on the wall, you also must consider the absorption characteristics of the material behind the panel (this is where almost all 'panel plans' go south and you're actually getting absorption at frequencies below what you'd expect the panel to provide);
> 
> 4. The more you absorb at the early reflection points, the more you run the risk of decreasing the width of the sound stage;



Your saying that I could be doing more harm than good adding more absorption to my first reflection points or just stating how it works? Here is ETC of my left and right seating positions. They are around 3' from the left or right walls. Each left or right speaker is more than a foot from each wall.











Here are the two middle seats, also in the front row.











All seats measured with 1/3 octave smoothing. Green are the seats closest to the walls.












> Quote:
> 5. The near field and off axis response of the speakers must be considered before you execute a plan of hanging fuzz on the walls ... diffusion may be the better choice.



I did some measurements outdoors, although I did not evaluate the off-axis response. You think I should go back and do so?



> Quote:
> 6. Also, at the early reflection points, you will not be achieving as much HF absorption as you may think due to the oblique angle of incidence from front speakers.



I use toe-in on my left and right speakers.


----------



## Dennis Erskine

Give me a call. I don't want to type that much ... Also...I need the magic decoder ring for the first plot. What are each of the colors....particularily the blue. This is all pretty, ah, ugly.


----------



## SteveMo

Thanks I will give a call then. Here is the key code. It is the same for the RT60.


Dark green = right seat

Lighter green = right seat2

Orange = left seat2

Blue = left seat











I will try and remeasure. Sometimes it will go away. If not I might try swapping enclosures on my left channel speaker to see if has something to do with having repaired that. There is also a steel beam in front of the left seat if that makes a difference. I used to measure the same thing in my right seat, or might have been the right speaker I was think of.


----------



## Dennis Erskine

Steve:


Let me ask some questions about what you are measuring here.


1. It appears that your plots of ETG are being done in different seating locations with all speakers driven. Is that the case? What you want is an ETG plot of each speaker individually measured from the same position.


2. How many drivers are in each speaker? ... and do they have front or rear ports? Each driver and each port will have its own initial arrival time.


3. The nominclature on the plots indicates "m" which means meters yet the last label at 8.5 is "ms" meaning milliseconds. What units are you using? Meters or milliseconds? If you look at your ETG of the two middle seats, you have an initial occurance of the direct sound at about .5 ms...that's about 6.5" (if it is meters, it is occuring at 1.5'). That would not be correct...it should represent the distance from your speaker to the microphone.


4. If you have all speakers driven, the first and second occurances of sound arrival would appear to be the difference between the arrival from one speaker vs the other. If that assumption is correct, your decay between the first, and subsequent arrivals would indicate over absorption. (On average it appears to be a 30dB drop ... way, too much).


5. Your last plot (which appears to be an RTA between 15Hz and 200Hz) shows you have a problem at your cross over (which would appear to be at 80Hz). If this is showing all speakers driven, the roll off (starting at about 90Hz) is too extreme. This is echoed in the earlier plot which extends to 2.0kHz. Effectively, your low frequency drivers need to be lowered by something in the range of 8dB. Other than that dip at 63Hz and the cross over issue, that looks good.


The ETG of the left/right front seats have the good news in that they both are pretty much the same. The hump at 8ms shows an 8.5' path difference. So, take a tape measure and stretch it out from the speaker to the seat, then add 8.5'. Next, hold the tape in the middle and move it around and find out what surface(s) it comes in contact with.




So...what exactly are you measuring? (and what are you using for your measurements?)

ETG's should be done one speaker at a time.

RTAs should be full range (20Hz to 20kHz)


----------



## Dennis Erskine

BTW, the 200Hz problem that is sometimes there, sometimes not, is phase related and due to the relatively short wave length, the difference in the measurements is due to small differences in your microphone placement. That's one reason single microphone measurements (as opposed to spatial averaging) is problematic.


----------



## SteveMo




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15382741
> 
> 
> Steve:
> 
> 
> Let me ask some questions about what you are measuring here.
> 
> 
> 1. It appears that your plots of ETG are being done in different seating locations with all speakers driven. Is that the case? What you want is an ETG plot of each speaker individually measured from the same position.



Yes, but the sum of each of the drivers and the individual ones look similar. Due to the large variance in SPL measuring each driver from an angle which is less than ideal (I need to fit more seats) I have been checking both to see how this interacts with the subs, looking for phase related problems. I had figured the ETG might reveal something with a timing related issue, and since I can't use waterfall plots, I don't know what else to use.


I will get some individual ones soon.



> Quote:
> 2. How many drivers are in each speaker? ... and do they have front or rear ports? Each driver and each port will have its own initial arrival time.



They are Polk Rti70 towers, not even the speakers I will be using in this room as I will need to replace these soon. Drivers are begining to fail on me etc. Here are the measurements outdoors. These were taken at ground plane 8' 7" the same distance as to the center of my front row. I fixed the tweeter in the blue measurement.











The two that measure lower are being used as surrounds now. I have looked inside them and the magnets do not look the same on speakers. Some have what looks like protective sheilding, and others do not. I thought the spec was to 20Hz or 22Hz when I bought them, and now looking at the Polk website it says 28Hz. I have the surrounds ports (a downward firing port) filled with foam because these ports are near ear level. The surrrounds not in the previous measurements. My left and right speaker were in the above measurements.

http://www.polkaudio.com/homeaudio/products/rti70/ 



> Quote:
> 3. The nominclature on the plots indicates "m" which means meters yet the last label at 8.5 is "ms" meaning milliseconds. What units are you using? Meters or milliseconds? If you look at your ETG of the two middle seats, you have an initial occurance of the direct sound at about .5 ms...that's about 6.5" (if it is meters, it is occuring at 1.5'). That would not be correct...it should represent the distance from your speaker to the microphone.



REW does not see a distance to the mic unless I use a loopback of my left channel. Should I do that then? 1.5 meters is around the distance they were to my front wall.



> Quote:
> 4. If you have all speakers driven, the first and second occurances of sound arrival would appear to be the difference between the arrival from one speaker vs the other. If that assumption is correct, your decay between the first, and subsequent arrivals would indicate over absorption. (On average it appears to be a 30dB drop ... way, too much).



My drop ceiling has alot of absorption in it above the speakers. Then there are corner traps, one with a GIK Pillar Trap in front of it. The floor ceiling corner has plywood filled with insulation. The left and right walls each have outdoor/indoor carpet at the first reflection points with 4 2" panels spaced 1" or 1 1/2" from the walls. During a remodel there was no option to sand a drywall insualtion, so outdoor indoor/carpet was placed over the area, and panels used to hide the imperfections. Before I treated the room the 200Hz problem with my mains was around the same. I have changed my room around alot. There are not many limitations to what I could change, but I do like it the way it has been turning out with regards to absorption. The measurements you are looking at are with my pre/pro level at -10, and we usually watch movies higher than this. When I listen at a higher SPL, it does not sound very dead. When I listen at lower SPL it is very focussed and transparent, but depending on the movie, I may loose some spaciousness. I hope that it will borderline somewhere from control room, and a listening room, with the potential for playing games, and music. Surround sound music seems to sound best.



> Quote:
> 5. Your last plot (which appears to be an RTA between 15Hz and 200Hz) shows you have a problem at your cross over (which would appear to be at 80Hz). If this is showing all speakers driven, the roll off (starting at about 90Hz) is too extreme. This is echoed in the earlier plot which extends to 2.0kHz. Effectively, your low frequency drivers need to be lowered by something in the range of 8dB. Other than that dip at 63Hz and the cross over issue, that looks good.



Yes that is very tricky and only until recently have I discovered this more in detail getting a pre/pro to measure better with. My actual source is my DVD player for which I have been using the Outlaw 950 crossover with at 80Hz. I can disable this and use my XA2 at a higher crossover of 100Hz, or 120Hz and still use LPCM. I am currently trying 100Hz again. That 63Hz null was around 20dB or so deep to begin with. It has been by far the most difficult to treat.



> Quote:
> The ETG of the left/right front seats have the good news in that they both are pretty much the same. The hump at 8ms shows an 8.5' path difference. So, take a tape measure and stretch it out from the speaker to the seat, then add 8.5'. Next, hold the tape in the middle and move it around and find out what surface(s) it comes in contact with.



I used my side walls and front wall as reference to measure with my meter stick and have not quite gotten that far. I will do so thanks for reminding me. The room is not prefectly symmetrical, so this makes takes awhile to get them right.



> Quote:
> So...what exactly are you measuring? (and what are you using for your measurements?)
> 
> ETG's should be done one speaker at a time.
> 
> RTAs should be full range (20Hz to 20kHz)



I'm using REW. The method for which I setup the speakers is explained here.

http://www.avsforum.com/avs-vb/showthread.php?t=1098205 


Please don't mind the last comment. Last time I asked about setup there someone asked why they were reading my thread, and my AVR died as result to improper setup.


I will get some new measurements and see if it looks better, but I have measurements looking like this currently. I was able to vanish the 200Hz peak in my RT60, but it came back.







It is somehow related to my right speaker, and has been. It shows if I use the speaker independently or measure the two left and right speakers at the same time.


The bellow measurement is after yesterday mornings experement with the crossover and phase. I have moved the speakers to the sides of the four subwoofers at my front wall. The only option I have is to reverse speaker wire connections, and I don't know which is correct. The soundstage sounds very close to me with them as they are now. Sound seems more in the room, less from the screen. I'm not sure it is correct quite yet.


I will remeasure with each speaker and see if that reveals anything. I use a PEQ for subwoofer equalization by the way because I am not allowed to have a false wall.


----------



## SteveMo




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15383609
> 
> 
> BTW, the 200Hz problem that is sometimes there, sometimes not, is phase related and due to the relatively short wave length, the difference in the measurements is due to small differences in your microphone placement. That's one reason single microphone measurements (as opposed to spatial averaging) is problematic.



Not heard about this before. Thanks.


----------



## Dennis Erskine

ah, do you know the difference between an RTA measurement and an RT60 measurement?


----------



## SteveMo




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15385290
> 
> 
> ah, do you know the difference between an RTA measurement and an RT60 measurement?



Yes, but is there is something you wanted to elaborate on? Did I go off topic? I was only trying to show that I canno't measure past 3K with my mic.


Edit: I see where there was some confussion. The last graph you were commenting on is not an RTA measurement of Pink Noise. That is frequency sweep in REW which is different. It actually looks like two swept sine waves but I forget the name. Sorry I missed that. That is the same that is used to generate the RT60.


----------



## SteveMo

I hope that I am doing this right. I took the left channel and used it as a reference, and checked the level after doing so which said I had a 84.3dB target. I had to adjust the channels some to get the levels to match more similar.


Here is how my HT was before treatments with and without equalization. I only had one subwoofer then and speakers were not in the same locations. My equalizer (blue) on the reciever I had added lots of boost. It also seemed to have cut the 100Hz area. Not sure and I could check but looks that way.





























Here are the latest measurements. I measured each channel in the center of the room with my mic at 45 degrees between the center left and right seats. The gold one is my right speaker which has the concrete foundation behind the wall, and the left speaker is with the beam in front of it and the partition wall on the left.





























Spectral Decay of Mains + Subwoofers


Left











Right











If these help, do you think that adding more absorption to the first reflection points is not a good idea? What about my left and right lower walls? I was wanting to add some thiner panels there bellow ear level. I could instead focus on doing that. The ETC window is in milliseconds.


----------



## Dennis Erskine

BTW, your outdoor measurements don't look at all correct. You mic should be approximately 1 meter from the speaker. How far away was your mic? The HF roll off shouldn't be anything like that.


----------



## SteveMo




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15390690
> 
> 
> BTW, your outdoor measurements don't look at all correct. You mic should be approximately 1 meter from the speaker. How far away was your mic? The HF roll off shouldn't be anything like that.



8' 7". I was not sure the high frequencies would be accurate with the lake at the bottom of the hill. The chirp after running sweeps must have been heard a at least 3 seconds afterwards and I could hear it durring the sweep as well. I could try furthur up the hill but I was really trying to focus on the larger drivers, one of which I had to replace.


----------



## SteveMo

I will try the panels for my left and right walls also at the first reflection points and see what happens then. Thank you.


----------



## rutlian

I recently build 2x4x2" and placed right behind my Left and Right channel I've heard improvement over my left/right channel, *Now I am thinking of putting same 2x4x2" behind my center channel how much improvement and is it worth putting a panel behind the* *center channel also*? Thanks my room is 13W'x20L'x8H' I have a 106" screen so treating the corner will be minimal space for me since I already have 2x4x2'' panel with my L/R speakers. I am also treating my first reflection points with 3 2x4x2" (sidewalls)


----------



## Dennis Erskine

Measurement/calibration sequence.


1. With all equipment (and the HVAC on) and no sound from the speakers, produce a 1/3rd octave full range RTA. This will give you the background noise floor in the room. This will provide a boundary between what your speakers are doing and what is ambient in the room.


2. Two near field measurements of each speaker. The microphone should be placed approximately 1' meter from the face of the speaker with the microphone aimed directly at the speaker. You may need to increase the distance beween the speaker and microphone slightly if you have multiple, widely spaced drivers. The measurement should be taken using pink noise first with bass management off (no crossovers active) and secondly with bass management and cross overs active. (We like to do a series of off axis measurements as well.) The subwoofer(s) should be measured as well. The purpose of these measurements are to: (1) establish that all drivers in the speaker are working correctly; (2) to give you a baseline measurement of what the speaker is producing so during calibration you can tell room/treatment impacts from the speakers' response; and, (3) determine if bass management is working correctly (correct slopes, 3 dB down at crossover frequency, etc.).


3. With the microphone (or array) set up for the primary listening position, disconnect all but one speaker at a time, and, using full range pink noise, measure the RTA of each individual speaker. You can, at this time level match the speakers as well. Bass management should be on. These plots can be overlaid against the nearfield to provide a rather obvious display of what the room is doing to response at the seating location. Large peaks and dips above 500Hz are most likely as a result of SBIR and point to a need for treatment (diffusion and/or absorption). Typically, you use 1/12 octave, C weighted pink noise. (1/12th isnt how we hear but provides the granularity needed to see problems). At this time, run an ETG (bass management on) for each speaker. This will show you SBIR and early reflections which are problematic. Based upon the later RT60 you plot for the room, you can determine whether absorption, diffusion or a combination thereof is most appropriate (over absorption of early reflection points is a common mistake). The biggest common cause of SBIR is from the front wall (behind the speakers) and the side wall immediately adjacent to the speakers. You can avoid most SBIR problems by keeping your main speakers at least 3.5' away from any surface (assuming a crossover of 80Hz). Subs should be placed closer than 3.5' from a wall (again assuming an 80 Hz crossover).


4. Turn off all speakers but the subs (bass management on) and position the microphone in a right tricorner of the room. The peaks in this plot will show you the actual modes in the room (real, not calculated) and their relative intensity. (Again, pink noise, full range). Run measurements at the primary seating location as well as other seating locations in the room. These latter measurements will provide the modal peaks and nulls which occur at individual seating locations. You might want to look for a null which is NOT a modal frequency.


5. You now want to position your various subs to reduce, moderate or eliminate nulls at primary listening positions. This measurement is best done using spatial averaging in each individual seating location....forget about seats within about 3.5' of a wall. Various types of tuned, or broadband absorption can be used to reduce both peaks and nulls.


6. Parametric EQ can be used to terminate peaks (won't help on the nulls).


7. Run another RTA of the subs, together (1/3 octave) and bring the average SPL level of the plot up to, or down to, the same average level of your center channel (L/C/R are already level matched).


It's very difficult to determine a treatment strategy until you actually measure what is happening the room. The various prediction models are not 100% accurate but certainly can provide a heads up with respect to what you might need. During calilbration and set up process, once you change something, do your measurements all over again to see what impact the change had. Also, most important...don't forget to LISTEN to your reference materials between changes.


----------



## SteveMo

I can't measure right now as I am out of town visiting family. I do have a measurement of the right corner but was made using a higher resolution and not using the RTA with Pink Noise fb. I was not able to measure with the crossover when I was doing that which is before I had my new pre/pro. I will go back and try again now that I can. I will try doing another measurement of the mains in the HT. Last time I tried doing this in my bedroom where I could position the mic away from the couch, it didn't seem to work and there seemed to be a dip in the response of my mains (probobly related to the angle in the ceiling) fairly large, but I will give it another try. To do this I bring the speaker out into the center of the room.


After that I measure something such as 8 points across the front row instead of the four then overlay them. It is difficult to position the mic however with each seat not being the same height. I will see if I can rig something since I don't have an expensive mic extention. Then I will place the new panels at the first reflection points over the other ones and check results.


listening is what I do more of but hearing anything wrong takes a long time to hear exactly what it is that sounds wrong about it.


----------



## CJO

Thanks Dennis for the excellent go-by.


CJ


----------



## John Schneider

Not quite sure if this is the right place for this, so apologies if I should go elsewhere.


I have problems with rattles and/or vibrations on the HVAC vent covers and returns in my room, and am trying to figure out how to eliminate them, or at least tame them considerably.


I thought about spraying some sort of coating on them (kind of like undercoating for cars), but thought maybe there was a manufacturer who already had a solution for this. My Google searches have been fairly useless.


TIA for any suggestions or pointing in the right direction.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *John Schneider* /forum/post/15422564
> 
> 
> Not quite sure if this is the right place for this, so apologies if I should go elsewhere.
> 
> 
> I have problems with rattles and/or vibrations on the HVAC vent covers and returns in my room, and am trying to figure out how to eliminate them, or at least tame them considerably.
> 
> 
> I thought about spraying some sort of coating on them (kind of like undercoating for cars), but thought maybe there was a manufacturer who already had a solution for this. My Google searches have been fairly useless.
> 
> 
> TIA for any suggestions or pointing in the right direction.



Is it the register that is rattling in it's seat or is it the register itself?


If it's the register you may have to replace it but try a lubricant first (WD-40 or an oil). If the register is rattling in it's seat, you might try a quick visit to Lowe's or Home Depot and have a look in the Caulk/weatherstripping section. There are plenty of solutions available.


----------



## John Schneider




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/15422719
> 
> 
> Is it the register that is rattling in it's seat or is it the register itself?
> 
> 
> If it's the register you may have to replace it but try a lubricant first (WD-40 or an oil). If the register is rattling in it's seat, you might try a quick visit to Lowe's or Home Depot and have a look in the Caulk/weatherstripping section. There are plenty of solutions available.



I think _everything_ is rattling (not the best constructed house out there







).


I probably should look at weatherstripping. I want to do my best not to interrupt the airflow - the AC in this house is already questionable at best (guess what's on the "needs replacing" list?). I know that when designing a dedicated HT room, a good HVAC system is a high priority, and there are designers and products out there for solving these issues. I wanted to look at some of the "professional" solutions and see if they are reasonably priced before I just tried a short term solution.


I'm definitely getting more annoyed by this stuff as I work on improving my system, so I guess I should do _something_ for a short term solution.


Thanks for the suggestions.


----------



## md1953

Over time, I have pretty much read this entire thread. I don't remember if my question has come up - I'm old and have a bad case of CRS. My AT screen will be ~40" from the back wall. I will be using a double layer of 1" of RC linacoustic on that wall. Should I do the same with ceiling and side walls that are behind the false wall? My Aerial speakers are bottom ported if that matters.


----------



## rutlian

According to Cinepanel FAQ's they recommend placing the panels 2 ft above the carpet, I am only placing mine 1 ft above the carpet, what are the pro's and cons of 1 and 2 ft? TIA


----------



## Rock_Hard

Hi there!

I've finally taken a few pictures of my basement/home theater because I'm interested in doing some acoustic treatments. Can someone take a peek at these and maybe give me some suggestions as what I would need, and where to place? I hope these pictures show enough of the basement to make a suggestion! I'm absolutely clueless when it comes to treatments so any help at all is very appreciated.


For the record, upfront there is a 12" and 10" subwoofer, and behind the couch in the corner opposite of the staircase is a 15" subwoofer as well. I know that sounds like it would be a disaster but I'm actually quite pleased with its quality of sound. Its not too boomy and covers the room quite well.


Thanks again!


Finally snapped some pics, unfortunately with a horrible camera.















































crooked picture. I had a phonecall as I was snapping the pic. Ugh, my trays on my ottoman are crooked too.


----------



## R Harkness

Almost on the starting line but need some input.


I'm reposting this GoogleSketchup image of my room. The whole screen wall will actually be black, covered in a yet-to-be-chosen black fabric. But as I said in my previous posts, I'm incorporating some acoustic absorption material above and below the screen to help absorb some of the bass bloat. The areas in which I'd put the acoustic material are represented in Blue.

The top portion is actually a sort of "valance" in which the roller track for the side masking panels (and the motor track) will be fitted. Above that I'm proposing to build acoustic material into the rest of it going up to the top of the ceiling.



 
 


What I need to know is this:


I'm not sure how to implement the acoustic material. As I said all areas of the screen wall will eventually be covered in light absorbing black fabric, including the acoustic material area.


Can the blue areas indicated on the picture be constructed of wood on the outside (and then covered in black fabric) with the acoustic material filling most of the inside? Will the material still do it's work with a shell of wood around it?


Or do we have to find some way of shaping only the acoustic material itself and wrapping it with fabric? (Doesn't sound like a great thing to do: the material I've been suggested to use is fibre-glass. I'd think I'd want wood between me and the fibre-glass wouldn't I?)


Thanks!


----------



## SteveMo

To continue where I left off, I have thought of way to keep the height the same. I could use some string, thread, or line with some push pins on each wall to the side of the seats using a level to check it was correct then mark have correct height to measure at. I could also mark using some tape or marker on the string or line to mark exactly where the RS meter would be for each test.


I have some questions first.


Do I wait until I have my left corner treated same as the right before I check these panels at different locations? I'm worried that it will make my measurements more difficult to look at. I have an idea of what the left corner not having the additional trap will cause, so should I just start with the panels and keep that in mind when looking at results? I am aware of what modes this effects.


I have another Pillar trap for the left corner and another pair of GIK 244's on the way also so I am wondering if I should just wait to measure when I have these also.


Another thing I am concerned with is that if I am moving my speakers out to the center of the room that is going to be a problem I would think having my screen area left untreated. Should I just measure the near field at the location there are at closer to panels and corner traps? I measure at 1 meter or slightly further with the mic aimed between the tweeter and the higher speaker driver?


----------



## David James

I'm thinking about building corner bass traps out of OC703 or eq. Rather then cut up the 2'x4' panels to make rectangles, I was thinking about constructing a corner frame and just putting sheets of the material inside, vertically. Here is an incredible crude and not to scale ascii drawing. The trap would be an 18" triangle, 4' high The "O" represent the 703. There would be air between the two layers. Any thoughts? How might it compare with a normal 24" 4" panel as purchased from the normal places, placed at an angle in the corner? How would adding a third layer of 703 improve it?

______________

|.........O........O

|......O........O

|...O.........O

|O.........O

|........O

|.....O

|...O

|.O


I'm kidding about it being better, I really have no clue, just thinking about it.


----------



## mondaycurse

I just finished my home theater/bedroom/living room area after 100 years of the space being a completely unfinished attic. The dimensions are about 15 wide and 28-29 deep, but I have 3-foot kneewalls which slant at about a 45 degree angle until it reaches the ceiling. Think bungalows. The room is in desperate need of sound treatment. Any ideas from people who tackled such rooms?


I have some OC703 panels that were saved when we remodeled the kitchen.


----------



## R Harkness

Dang, a lot more questions than answers going on in this thread, these days.


----------



## pepar

Accurate. Timely. Free.


Pick two.


----------



## David James




> Quote:
> Originally Posted by *pepar* /forum/post/15534548
> 
> 
> Accurate. Timely. Free.
> 
> 
> Pick two.



Two? At this point, one would be nice


----------



## Screen Shot

I have several 6 panel pine doors in my home theater room including French doors leading into the room, and 2 sets of folding doors on an 8' closet. I am in the process of painting them.


Does anyone know of any acoustic panel/products that could be attached to the panel sections of the doors?


Picture enclosed.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Screen Shot* /forum/post/15542399
> 
> 
> Does anyone know of any acoustic panel/products that could be attached to the panel sections of the doors?



Your best bet is panels on stands that can be moved out of the way when needed. Or, optionally, hinged panels that stay in place without a stand. Photos below.


--Ethan


----------



## Screen Shot




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15544982
> 
> 
> Your best bet is panels on stands that can be moved out of the way when needed. Or, optionally, hinged panels that stay in place without a stand. Photos below.
> 
> 
> --Ethan



Ethan, thanks for the note and pics, however, I don't think those options will work for me. Do you (or anyone else) have a panel that fits in the door panel (i.e., each 6 panel door would have 6 inserts that would be attached)?


----------



## rutlian

Ethan I watched all your acoustical video 101 (I call it that way) they are very informative and very easy to understand, thank you for sharing your knowledge in this forum.


I also would like to cover my entry door (the side inside the room) of acoustic panel, since corner traps is impossible in that area my plan is to cover it with 1 inch OC703. Is the thinkness good enough for absorption purposes?


----------



## Ethan Winer

One inch thick 703 is okay for side-wall reflections, though two inches thick is even better. Or use 705 which absorbs to a lower frequency than 703 when only one inch thick.


--Ethan


----------



## Daveyd

I'm not sure where to post but it does have to deal with acoustics (but not home theater) so I thought I'd throw it in here










I am going to build a bedroom (12.5 x 12.5) in my basement for my 15yr old daughter. Her bedroom will be right below my bedroom










I need to build the bedroom with a drop ceiling. The room will have HVAC via our furnace/central AC. What is the best way to build the bedroom to accomplish 2 things:


1. Retain as much heat as possible so it wont be real cold during the winter months and


2. Provide as much soundproofing as possible so she doesn't keep me up all night


----------



## will1383




> Quote:
> Originally Posted by *Screen Shot* /forum/post/15545108
> 
> 
> Ethan, thanks for the note and pics, however, I don't think those options will work for me. Do you (or anyone else) have a panel that fits in the door panel (i.e., each 6 panel door would have 6 inserts that would be attached)?



I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.


----------



## Weasel9992




> Quote:
> Originally Posted by *will1383* /forum/post/15553373
> 
> 
> I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.



That sounds like a great DIY idea. I don't know of anything ready-made to solve that problem.


Frank


----------



## will1383




> Quote:
> Originally Posted by *Daveyd* /forum/post/15553286
> 
> 
> I'm not sure where to post but it does have to deal with acoustics (but not home theater) so I thought I'd throw it in here
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I am going to build a bedroom (12.5 x 12.5) in my basement for my 15yr old daughter. Her bedroom will be right below my bedroom
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I need to build the bedroom with a drop ceiling. The room will have HVAC via our furnace/central AC. What is the best way to build the bedroom to accomplish 2 things:
> 
> 
> 1. Retain as much heat as possible so it wont be real cold during the winter months and
> 
> 
> 2. Provide as much soundproofing as possible so she doesn't keep me up all night



1. retaining heat is as easy as building walls and putting insulation in them. If you are really worried, use r-19 and build the walls as 2x6. Putting in a drop celing and then putting some insulation between the floor and the drop ceiling will help as well.


2. do you have access to the floor in your bedroom? If so, you can start by putting a sound mat on the floor in your bedroom. Expensive but will help alot. If you have carpet, you can then cover it over with the carpet. The drop ceiling will help as well, just make sure you buy the "sound proof" tiles.

As for the walls, you could use some RISC-2 (I think that's the model) to separate the walls from the floor joists, and that would help isolate the sound even more. Outside of that, there really isn't much else to do without making the build a lot more complicated.


3. you could always deny her the stereo in the room so she's stuck using the computer and ipod for music, and then limit the speaker sizes to something reasonable.











But, these are really sound isolation construction techniques, where as this thread is really aimed at improving room acoustics. They really are two separate entites - sound isolation and acoustical improvements.


----------



## will1383




> Quote:
> Originally Posted by *Weasel9992* /forum/post/15553409
> 
> 
> That sounds like a great DIY idea. I don't know of anything ready-made to solve that problem.
> 
> 
> Frank



I do not know of any ready-made stuff either, and I need to make sure it doesn't vibrate against the back of the door, so this is the technique I'm going to use.


So, I'll hang a thin, permanent frame on the door itself, paint it to match the door (so it'll almost look like an additional trim element). Then my framed, 2" 703 will be hung on that. I don't know yet how I'm going to hang it on there, but I'm still a ways off from doing this part of my build. I don't have a screen yet and I still have to get my rta software running to take a prelim reading of the room. In addition, I don't have all my trim work up yet, so that has to go first.


----------



## Daveyd




> Quote:
> Originally Posted by *will1383* /forum/post/15553422
> 
> 
> 1. retaining heat is as easy as building walls and putting insulation in them. If you are really worried, use r-19 and build the walls as 2x6. Putting in a drop celing and then putting some insulation between the floor and the drop ceiling will help as well.
> 
> 
> 2. do you have access to the floor in your bedroom? If so, you can start by putting a sound mat on the floor in your bedroom. Expensive but will help alot. If you have carpet, you can then cover it over with the carpet. The drop ceiling will help as well, just make sure you buy the "sound proof" tiles.
> 
> As for the walls, you could use some RISC-2 (I think that's the model) to separate the walls from the floor joists, and that would help isolate the sound even more. Outside of that, there really isn't much else to do without making the build a lot more complicated.
> 
> 
> 3. you could always deny her the stereo in the room so she's stuck using the computer and ipod for music, and then limit the speaker sizes to something reasonable.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> But, these are really sound isolation construction techniques, where as this thread is really aimed at improving room acoustics. They really are two separate entites - sound isolation and acoustical improvements.





My floor in my bedroom is all carpeting. Should I stuff R19 insulation in the cliling joists in the basement where the bedroom is going to be built? I've read up on the Owens Corning QuietZone insulation but it seems like peope are saying they are just like regular insulation and not worth the money.


Is there a sound isolation forum on here that maybe I could post this in?


----------



## ScruffyHT




> Quote:
> Originally Posted by *Daveyd* /forum/post/15554032
> 
> 
> My floor in my bedroom is all carpeting. Should I stuff R19 insulation in the cliling joists in the basement where the bedroom is going to be built? I've read up on the Owens Corning QuietZone insulation but it seems like peope are saying they are just like regular insulation and not worth the money.
> 
> 
> Is there a sound isolation forum on here that maybe I could post this in?




Read the library section at this website for soundproofing solutions www.soundproofingcompany.com


----------



## will1383




> Quote:
> Originally Posted by *Daveyd* /forum/post/15554032
> 
> 
> My floor in my bedroom is all carpeting. Should I stuff R19 insulation in the cliling joists in the basement where the bedroom is going to be built? I've read up on the Owens Corning QuietZone insulation but it seems like peope are saying they are just like regular insulation and not worth the money.
> 
> 
> Is there a sound isolation forum on here that maybe I could post this in?



I would just use simple insulation.


I went through a fairly extensive sound isolation build, and outside of bass (low frequencies) there is no other sound going through the house, anywhere, unless I leave the doors open







. I don't have ny door sealed up nor any lfe traps so I should be able to reduce the bass noise some.


----------



## ScruffyHT




> Quote:
> Originally Posted by *Daveyd* /forum/post/15553286
> 
> 
> 
> I need to build the bedroom with a drop ceiling.



Is there a reason why you want a drop ceiling as opposed to drywall ?


your best bet is to use RSIC clips with hat channel and then hang 2 layers of 5/8 drywall ... in between the drywall add 2 tubes of green glue per sheet ( www.greengluecompany.com )


----------



## zamboniman

Any thoughts on putting treatments (either absorbtion or diffusion) behind floor to ceiling curtains made of GOM?


I've got some interesting side wall features which are asymetrical from left wall to right wall (egress window and nook) that I'm looking to clean up asthetically by hiding with maybe curtains or similar on both sides. This area doesn't lend itself well to the typical fabric wall approach. I'm looking to do acoustic treatment at the same time. Was thinking of putting required absorbtion and/or diffusion in proper places but hide all of it with GOM curtains. Easy to pull back and use window or access nook.. ??? Is this destined for failure?


----------



## Daveyd




> Quote:
> Originally Posted by *will1383* /forum/post/15554068
> 
> 
> I would just use simple insulation.
> 
> 
> I went through a fairly extensive sound isolation build, and outside of bass (low frequencies) there is no other sound going through the house, anywhere, unless I leave the doors open
> 
> 
> 
> 
> 
> 
> 
> . I don't have ny door sealed up nor any lfe traps so I should be able to reduce the bass noise some.



Are there any "sound deadening" drop ceiling tiles that are highly recommended?


----------



## will1383




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/15554125
> 
> 
> Is there a reason why you want a drop ceiling as opposed to drywall ?
> 
> 
> your best bet is to use RSIC clips with hat channel and then hang 2 layers of 5/8 drywall ... in between the drywall add 2 tubes of green glue per sheet ( www.greengluecompany.com )



Expensive, time consuming, and you gotta know what you are doing hanging drywall, and making all the proper connections.


My comments are based on the assumption of two things:


1. It's a kids room, so spending a lot of money on sound isolation in an average home isn't worth the extra expense.


2. The person isn't an expert in construction techniques, and was looking for some relatively simple, inexpesive solutions to help reduce the amount of noise that travels between the kid's room and their bedroom.


The GG/drywall/floating wall and ceiling solution is by far the best, but for a room that is 12.5' x 12.5', you can expect to spend an additional $1000+ just for the sound isolation materials if going that route. Not to mention the fact that if you are not experienced in construction, it is going to either take a very long time to build, or you aren't going to build it right. Either way, neither of these options is realistic.


Furthermore, if you are going to get into full sound isolation, then you must address flanking issues such as HVACC pipes, electrical boxes, and of course the doorway.


So, the GG/drywall/hat channel method is going to be wasted money if you don't go through the entire sound isolation construction process.


I'm not saying you shouldn't do it, nor that it is out of reach, but there is a significant amount of effort, planning, design, consideration, and knowledge that is necessary to build it the right way.


So, I recommend some basic techniques to offset the sound, and then just make sure you don't have her put in a 1000-watt stereo system, and it'll be as good as you can get without going through the ordeal of trying to understand, design, and implement a rather intricate building process.


----------



## will1383




> Quote:
> Originally Posted by *Daveyd* /forum/post/15554141
> 
> 
> Are there any "sound deadening" drop ceiling tiles that are highly recommended?



You'd have to look as I went a different construction method and haven't used the tiles personally. I know there are a number of people on this forum who use them. Usually you can find drop tiles that are labelled as sound-deadening or sound proofing.


----------



## David James

My theater is in the basement. There is a staircase which leads from the basement to the main floor. The staircase opening is in the back and directly faces the front left speaker. The stairs go up some steps where there is a small landing then switch back the rest of the way up to the main floor. It seems I'm getting sound bouncing up the stairway and up into the main floor. I don't want to put a door in. Would absorbent panels, like OC703 help reduce the sound. I'm thinking maybe on walls B and C, which face the theater?


A___________

B| ....| | | | | -> Main Floor

C| ....| | | | |


----------



## Daveyd




> Quote:
> Originally Posted by *will1383* /forum/post/15554209
> 
> 
> Expensive, time consuming, and you gotta know what you are doing hanging drywall, and making all the proper connections.
> 
> 
> My comments are based on the assumption of two things:
> 
> 
> 1. It's a kids room, so spending a lot of money on sound isolation in an average home isn't worth the extra expense.
> 
> 
> 2. The person isn't an expert in construction techniques, and was looking for some relatively simple, inexpesive solutions to help reduce the amount of noise that travels between the kid's room and their bedroom.
> 
> 
> The GG/drywall/floating wall and ceiling solution is by far the best, but for a room that is 12.5' x 12.5', you can expect to spend an additional $1000+ just for the sound isolation materials if going that route. Not to mention the fact that if you are not experienced in construction, it is going to either take a very long time to build, or you aren't going to build it right. Either way, neither of these options is realistic.
> 
> 
> Furthermore, if you are going to get into full sound isolation, then you must address flanking issues such as HVACC pipes, electrical boxes, and of course the doorway.
> 
> 
> So, the GG/drywall/hat channel method is going to be wasted money if you don't go through the entire sound isolation construction process.
> 
> 
> I'm not saying you shouldn't do it, nor that it is out of reach, but there is a significant amount of effort, planning, design, consideration, and knowledge that is necessary to build it the right way.
> 
> 
> So, I recommend some basic techniques to offset the sound, and then just make sure you don't have her put in a 1000-watt stereo system, and it'll be as good as you can get without going through the ordeal of trying to understand, design, and implement a rather intricate building process.




That basically sounds like me.


Another reaso for not drywalling the ceiling is for ease of access. The ceiling in her room is the main access point for all the wiring (telephone, coax, etc) coming in from outside.


I do have experience hanging drywall on the ceiling as I finished anohter part of my basement and drywalled that ceiling...which pretty much sucked. Since its just a teenager's room, a drop ceiling would do fine.


I can double up on the drywalls on the walls with Green Glue in needbe but boy that stuff is expensive!!


I would think my main issue would be the ceiling as my HVAC vent runs in a ceiling joist that would be part of her bedroom. As it is now, when someone is beneath my bedroom in that part of the basement I can hear every clearly.


----------



## will1383




> Quote:
> Originally Posted by *David James* /forum/post/15554338
> 
> 
> My theater is in the basement. There is a staircase which leads from the basement to the main floor. The staircase opening is in the back and directly faces the front left speaker. The stairs go up some steps where there is a small landing then switch back the rest of the way up to the main floor. It seems I'm getting sound bouncing up the stairway and up into the main floor. I don't want to put a door in. Would absorbent panels, like OC703 help reduce the sound. I'm thinking maybe on walls B and C, which face the theater?
> 
> 
> A___________
> 
> B| ....| | | | | -> Main Floor
> 
> C| ....| | | | |


----------



## Daveyd

Here is the one side of the basement I built from scratch. Nothing but an open area before...











My daughter's bedroom is going to be on the other side of the door to the right. The 2 sides of the basement are seperated by a block wall


----------



## will1383




> Quote:
> Originally Posted by *Daveyd* /forum/post/15554402
> 
> 
> That basically sounds like me.
> 
> 
> Another reaso for not drywalling the ceiling is for ease of access. The ceiling in her room is the main access point for all the wiring (telephone, coax, etc) coming in from outside.
> 
> 
> I do have experience hanging drywall on the ceiling as I finished anohter part of my basement and drywalled that ceiling...which pretty much sucked. Since its just a teenager's room, a drop ceiling would do fine.
> 
> 
> I can double up on the drywalls on the walls with Green Glue in needbe but boy that stuff is expensive!!
> 
> 
> I would think my main issue would be the ceiling as my HVAC vent runs in a ceiling joist that would be part of her bedroom. As it is now, when someone is beneath my bedroom in that part of the basement I can hear every clearly.



Run a seperate duct to the room below you. You could also change out the current metal duct for a flexible, insulated duct, and that would help out A LOT. It's also pretty cheap, like less than $60, depending how long the run is.


In this case, it seems like you are only worried about an over abundance of noise coming through the floor and into your bedroom. At this point, if you were to spend the $150 for the wall isolation clips, you would separate the wall from the floor joists, which has the same effect as the hatchannel/floating wall design, and is considerably cheaper...


the drop ceiling/insulation route seems to work pretty well from everyone that I've spoken too. So combine that with a separate hvacc duct, and using the soft ducts instead of the metal, and you should have some decent success.


Will it be perfect? No. Will you hear a party going on down there. Ya, most definitely. But it should dissipate the sound enough so that her just living down there normally won't bother you much, if at all. And I believe this is your overall goal, not to drown out parties and loud music.


If it isn't, please let us know and we can point you in a different direction.


----------



## David James




> Quote:
> Originally Posted by *will1383* /forum/post/15554471
> 
> 
> I would do a couple of things. I would start with the door at the top of the stairs. Replace it with a safe and sound door - aka a solid core door. I would then make sure you seal all the edges using a thin, foam seal, similar to an exterior door. You should be able to find a solution that will work with your interior door frame so you don't have to replace the entire frame with slotted jams for exterior door rubber. Then, get a door stop for the bottom of the door that will seal it up against the floor.
> 
> 
> Don't forget to use a really small amount of silcon to seal up the door knob itself as well.
> 
> 
> I would address that FIRST, then worry about the sound bouncing off the walls.
> 
> 
> Once you address the door, then you can begin figuring out where the reflection points are in your stairwell, and then address them with acoustic panels. That will also help.
> 
> 
> Now, of course the type, and amount of panel you use depends on the frequencies you are trying to cover up. Bass (Low Frequencies) is almost a whole different animal.
> 
> 
> My stairwell is outside of my HT, but it abuts the front wall of my HT, and with the door open, base and sound reverburate the stairwell, almost amplifying the sound. I might need to actually do some additional treatments in the stairwell, but I won't do anymore than addressing the door at the top of the stairs until I get the HT completely done.



Thanks for the reply.


We had a door at the top of the stairs, but for various reasons, decided to remove it so that idea, while a good one, isn't a going to happen. I'm not even trying to address the bass, only the higher frequencies. I don't know how sound waves travel so considering the stairway is like a "tunnel", I would think the waves would travel up the "tunnel", bounce against the well in the landing and reflect up the "tunnel" to the main floor, hence my thinking of putting panels on that wall.


Sure sounds good to my simple brain







I suppose I could, before hanging some in the theater temporarily hang them there and see what happens.


----------



## will1383

My HT has duct work, and the water pipes to the front yard (sprinkler system) and to my 1st floor bathroom, and the septic pipes. I had to come up with some unique ways to allow access to what I had to, and change around some plumbing and other things to make sure I could access what I needed if the need ever arose.


All of my main electrical and other stuff is on the backside of my main support beam, and I didn't put a ceiling in that area.


----------



## will1383




> Quote:
> Originally Posted by *David James* /forum/post/15554558
> 
> 
> Thanks for the reply.
> 
> 
> We had a door at the top of the stairs, but for various reasons, decided to remove it so that idea, while a good one, isn't a going to happen. I'm not even trying to address the bass, only the higher frequencies. I don't know how sound waves travel so considering the stairway is like a "tunnel", I would think the waves would travel up the "tunnel", bounce against the well in the landing and reflect up the "tunnel" to the main floor, hence my thinking of putting panels on that wall.
> 
> 
> Sure sounds good to my simple brain
> 
> 
> 
> 
> 
> 
> 
> I suppose I could, before hanging some in the theater temporarily hang them there and see what happens.



Well, having it open to upstairs isn't going to do much for anything, lol. But, I completely understand the customization to meet your living style and needs.


If there's room, I'd put the door back







sounds like problem solved, for considerably less money as well.










Anyways, you are correct in that the frequencies will 'bounce' their way to the top, so you can add panels in appropriate places to help absorb the bounce.


Now, to determine which points to place them? I'm going to have to punt that to one of the people who knows the math off the top of their head...


I'd use a mirror for the first point and base that off the speaker location. That would be my starting point. Then add the others based of the first panel. But hang them temporarily, so you can see if they make any real difference.


Problem is you can't simply buy this stuff and expect to be able to return it if it doesn't work...


----------



## David James




> Quote:
> Originally Posted by *will1383* /forum/post/15554629
> 
> 
> If there's room, I'd put the door back
> 
> 
> 
> 
> 
> 
> 
> sounds like problem solved, for considerably less money as well.



Less money? Do you realize how much a good divorce lawyer charges










> Quote:
> Originally Posted by *will1383* /forum/post/15554629
> 
> 
> Problem is you can't simply buy this stuff and expect to be able to return it if it doesn't work...



Indeed, I'm struggling even to find a place locally (with 50 miles) to even buy this stuff.


Thanks again for your advice.


----------



## ScruffyHT




> Quote:
> Originally Posted by *will1383* /forum/post/15554209
> 
> 
> Expensive, time consuming, and you gotta know what you are doing hanging drywall, and making all the proper connections.
> 
> 
> 
> 
> So, the GG/drywall/hat channel method is going to be wasted money if you don't go through the entire sound isolation construction process.



LOL ... you are joking right ? Expensive, time consuming, additional $1000+ ???


I ran the numbers and came in at less than $400 for RSIC, Hat channel, DD GG for the ceiling with left over green glue











if it was me I would be concerned that if you can hear what it going on below you so well what about sound going the other way too


----------



## David James

One other question. I'm going to put wedges in the corners of my theater, like described here .


I'm wondering if anyone can quantify the impact difference between going halfway up the corner versus all the way or 3/4 way etc. Is it simply linear, go 1/2 achieve 1/2 benefit?


----------



## will1383




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/15554722
> 
> 
> LOL ... you are joking right ? Expensive, time consuming, additional $1000+ ???
> 
> 
> I ran the numbers and came in at less than $400 for RSIC, Hat channel, DD GG for the ceiling with left over green glue
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> if it was me I would be concerned that if you can hear what it going on below you so well what about sound going the other way too



THat's $400 for ONLY the ceiling. Multiply that times 5 for the rest of the room, and you're at roughly $2000... 4 walls and the ceiling.


what I'm suggesting costs that much for the entire room, and should provide enough to meet his needs.


In addition, he stated he needs to have access to the ceiling area because of electrics and such, so going the GG/dry wall route isn't practical, because if he ever has to cut into it, all that money, time, effort is wasted...


----------



## cuzed2




> Quote:
> Originally Posted by *will1383* /forum/post/15554533
> 
> 
> Run a seperate duct to the room below you. You could also change out the current metal duct for a flexible, insulated duct, and that would help out A LOT. It's also pretty cheap, like less than $60, depending how long the run is.
> 
> 
> In this case, it seems like you are only worried about an over abundance of noise coming through the floor and into your bedroom. At this point, if you were to spend the $150 for the wall isolation clips, you would separate the wall from the floor joists, which has the same effect as the hatchannel/floating wall design, and is considerably cheaper...
> 
> 
> the drop ceiling/insulation route seems to work pretty well from everyone that I've spoken too. So combine that with a separate hvacc duct, and using the soft ducts instead of the metal, and you should have some decent success.
> 
> 
> Will it be perfect? No. Will you hear a party going on down there. Ya, most definitely. But it should dissipate the sound enough so that her just living down there normally won't bother you much, if at all. And I believe this is your overall goal, not to drown out parties and loud music.
> 
> 
> If it isn't, please let us know and we can point you in a different direction.



Daveyd,


I can see what you are trying to accomplish (economical sound isolation between living spaces) and think i can give you some practical nput as to how effective the "economy route" is (or isn;t) :


For my theater build, I have an open floor plan that does not lend itself well to DD, GG, and other isolation methods. I just wanted to cut down the "living space noise" coming from the kitchen above into my theater below.


I filled the floor joists above my theater with 12" of batt insulation, and then finished with a decorative dropped ceiling.


What I found: Normal noises from above including sliding chairs on a tile floor, kitchen footsteps, conversations, dishwasher loadings, etc..were reduced by ~80%. However; when I crank the bass in the theater; it seems that the Bass getting to the kitchen above has only been reduced by 20%.


So for the economy route I would guesstimate:


~80% reduction for normal activities,

and only ~20% reduction for bass heavy music or movies


Hope this helps?


----------



## Daveyd




> Quote:
> Originally Posted by *cuzed2* /forum/post/15556136
> 
> 
> Daveyd,
> 
> 
> I can see what you are trying to accomplish (economical sound isolation between living spaces) and think i can give you some practical nput as to how effective the "economy route" is (or isn;t) :
> 
> 
> For my theater build, I have an open floor plan that does not lend itself well to DD, GG, and other isolation methods. I just wanted to cut down the "living space noise" coming from the kitchen above into my theater below.
> 
> 
> I filled the floor joists above my theater with 12" of batt insulation, and then finished with a decorative dropped ceiling.
> 
> 
> What I found: Normal noises from above including sliding chairs on a tile floor, kitchen footsteps, conversations, dishwasher loadings, etc..were reduced by ~80%. However; when I crank the bass in the theater; it seems that the Bass getting to the kitchen above has only been reduced by 20%.
> 
> 
> So for the economy route I would guesstimate:
> 
> 
> ~80% reduction for normal activities,
> 
> and only ~20% reduction for bass heavy music or movies
> 
> 
> Hope this helps?




Thats probably the route I am going to take. I'll fill the ceiling joists and walls with insulation and find a decent sound absorbing tile for a drop ceiling. I'll buy a solid core door and use it for her room as well.


If it gets too cold in the winter time, I can always buy a small electric space heater.


Should the ceiling joists be installed with the paper side up or down...or does it really matter if its covered by a drop ceiling?


Right across from her room is the laundry room. I am not going to but any type of ceiling in there but will put insulation in the ceiling joists so helping with sound. Since there will be no ceiling should the paper side go up, facing the floor above or down facing the basement floor?


----------



## cuzed2

For above my dropped ceiling I went with unfaced, I really don't think it makes any difference for sound.


As for moisture concerns

It should also not make a difference if you are insulating between 2 living (HVAC) spaces.


HOWEVER for code and fire safety issues; I personally would NOT leave either type of insulation exposed in living area, and then there is the "itch factor" with exposed unfaced insulation!


----------



## rutlian




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15552457
> 
> 
> One inch thick 703 is okay for side-wall reflections, though two inches thick is even better. Or use 705 which absorbs to a lower frequency than 703 when only one inch thick.
> 
> 
> --Ethan




Thanks, I have 2'' in my mind, I am just thinking if I put 1'' thick in my door it will not too bulky or thicky, But I will check 705 also thanks for the advise.


----------



## rutlian




> Quote:
> Originally Posted by *will1383* /forum/post/15553373
> 
> 
> I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.



I was thinking the same way too for my door, mine is not 6-paneled door now that you mentioned it I might go for it I was thinking 1'' OC703 but I will use OC705 instead, and you are right about the handle I am thinking how am I go around it.


If you finish yours first, can you post some picture of it? thanks I appreciate it.


----------



## ScruffyHT




> Quote:
> Originally Posted by *will1383* /forum/post/15554872
> 
> 
> THat's $400 for ONLY the ceiling. Multiply that times 5 for the rest of the room, and you're at roughly $2000... 4 walls and the ceiling.
> 
> 
> what I'm suggesting costs that much for the entire room, and should provide enough to meet his needs.
> 
> 
> In addition, he stated he needs to have access to the ceiling area because of electrics and such, so going the GG/dry wall route isn't practical, because if he ever has to cut into it, all that money, time, effort is wasted...



First of all he would not be using RSIC and hat track on the walls










The ceiling is the biggest leak for sound so he could try the ceiling only first of all and then decide if the walls would be necessary


secondly he would be using at least ONE layer of drywall on the walls already plus the cost of the drop ceiling whatever that is


thirdly you are in a mood to argue and I am not ... so no more posts by me on this subject










It is all moot anyway as the OP wants access to the ceiling although that could all be solved with some conduit but hey ... you get what you get


----------



## csamos

After having my theater for 5 years now, I finally got around to analyzing first reflection points and building/mounting acoustic panels. I used 2" thick OC 703 with 2" air gaps for the acoustic panels. I also used 4" thick OC 705 for several corner bass traps. The improvement in the audio is amazing. I've only auditioned a few movie scenes so far, but the difference is tremendous. Even my girlfriend (she's not a video/audiophile) thought the asteroid chase scene in Star Wars Episode II was incredible sounding.










Here are some panels on one wall:











I mounted 4 on the ceiling in front the projector. You can also see a bass trap at the ceiling, as well as part of an acoustic panel to the right of the component cabinet.











There are bass traps in the front corners of the room and along the right side at the ceiling. This was before the acoustic panels were installed, and all mounting hardware has been painted black as well, so it's no longer visible.











It was a much longer task than I anticipated, but I'm so glad I finally did it.


----------



## 04FLHRCI

Does anyone have any insight to provide here?


I've been wondering the same as David; I expect to begin my treatments in early February.


Larry



> Quote:
> Originally Posted by *David James* /forum/post/15554729
> 
> 
> One other question. I'm going to put wedges in the corners of my theater, like described here .
> 
> 
> I'm wondering if anyone can quantify the impact difference between going halfway up the corner versus all the way or 3/4 way etc. Is it simply linear, go 1/2 achieve 1/2 benefit?


----------



## David James

 This link was posted in the subwoofer thread but I think this thread may generate more responses here. I'm specifically looking at their corner bass traps (NC-160).


They list NRC ratings but not specifically for that model (I emailed them for the numbers).


Has anyone else used them or talked to someone who has?


----------



## chasiliff

I am setting up a theater room in my basement with existing ceiling drywall. The cost and work involved to double the drywall would be exorbitant, so right now I am hoping to avoid that. Do any of you have experience with the sound improvement when cellulose is blown into a ceiling or other space? My joists are composed of 2X4 trusses that are about 15 inches deep from floor above to drywall ceiling. I'd like to blow in the insulation. (I know it's messy. I've started sealing all possible holes into the ceiling excepting access ports for blowing the insulation.)


----------



## agmitch

Does anyone know what happed to penngray? Back around page 110(?) he was about to post results on his super chunk trap build with acousitc cotton insulation. I am wondering how it went and how they perform. Anyone else have experience with this stuff. I plan to build several bass traps and perhaps hang some panels in the first reflection points of my room.



bill


----------



## (Berk)

Hi Everyone,


I've been reading, lurking and learning over the past several months. I have finally started on my HT and am hoping to get some advice from the wealth of knowledge that is represented in these forums.


Any suggestions will be very much appreciated. I posted this on the design and construction thread, but my questions are much more about sound accoustics than construction. Plus I got no replies there yet.


The room I am building is a concrete bunker which is under my double car garage. This means that the floor, all four walls and the ceiling (which is a suspended slab) are all 8" thick concrete. Only one of these walls and about 4 feet of another wall is on the other side of the living space of the basement. All of the walls are below grade and there are no windows and only one door. The inside measurements are approximately 22 * 20 feet. Because of the garage above, the ceiling does have a slope of about 4 inches from from front to back. The ceiling height ranges from approximately 7'-6" - 7'-10 inches. So far I have completed framing the interior walls and with a soffit box that the HVAC pipes have been run through and I will also be putting a rope light of some sort up in the box.


This is where I'm at right now.










In the second pic, I'm trying to show how the ceiling slopes slightly.











The last pic shows the room before the ceiling/suspended garage floor was put on. The doorway in the first pic is the same as the opening in this one.











My goal is to have a 5.1 or 7.1 system with a front projector and a 106 inch screen. The room will also be a music room for my kids who play electric guitar, drums, and keyboards and a few other instruments. I have read alot on how to do the accoustic treatments to the walls floor and ceiling, but my question is what do I do about the slope. Is it worth giving a few more inches away to level the ceiling off by doing a drop ceiling, do I just leave it concrete, glue some foam up there or something else? If I keep the slope, what is there a better way to position the screen, with the slope increasing as you move away from the screen or decreasing? I have not done any electrical or electronic wiring yet so all options are still open.


Lastly, I have an 11 year old daughter who is a dancer, I would love to put a cork or laminate floor in here for her to practice would that be a bad idea for sound? Could area rugs on a harder surface floor work or is carpet the only option?




Thanks,

Berk


----------



## pepar




> Quote:
> Originally Posted by *(Berk)* /forum/post/15619867
> 
> 
> my question is what do I do about the slope. Is it worth giving a few more inches away to level the ceiling off by doing a drop ceiling, do I just leave it concrete, glue some foam up there or something else? If I keep the slope, what is there a better way to position the screen, with the slope increasing as you move away from the screen or decreasing? I have not done any electrical or electronic wiring yet so all options are still open.



If the ceiling is concrete and sloped, I don't think any suspended ceiling will change it acoustically where the bass is concerned. And speaking as someone who purposely built (20 years ago) a "media room" with a sloped ceiling, I would build the room rectangular the next time. It's not that is can't be treated properly to achieve good sound, it's just that a non-rectangular room makes it impossible to plan LF treatments in advance as all of the modeling software is for rectangular rooms.


Plan on a LOT of bass traps as you will not have the absorption that normally occurs with studded interior walls.


----------



## cuzed2

Berk,


Wow - A concrete bunker room. I am JEALOUS!! Aside from a slightly low ceiling; it seems you have an EXCELLENT space.


Actually the low ceiling is a minor hurdle because it looks like there are minimal overhead restrictions. As long as you locate you PJ with care it should work out fine.


As for your acoustic questions; i will defer to the experts that lurk on this excellent thread


Best of Luck and please share photos with us on one of the construction threads....


----------



## (Berk)




> Quote:
> Originally Posted by *pepar* /forum/post/15620827
> 
> 
> If the ceiling is concrete and sloped, I don't think any suspended ceiling will change it acoustically where the bass is concerned. And speaking as someone who purposely built (20 years ago) a "media room" with a sloped ceiling, I would build the room rectangular the next time. It's not that is can't be treated properly to achieve good sound, it's just that a non-rectangular room makes it impossible to plan LF treatments in advance as all of the modeling software is for rectangular rooms.
> 
> 
> Plan on a LOT of bass traps as you will not have the absorption that normally occurs with studded interior walls.




Thanks for your reply Pepar, I will finish the interior walls per normal standards.. framed, insulated, drywalled. As shown in the pictures, framing is already complete. Are you saying that without a finished ceiling I will need lots of bass traps or were you thinking all the walls were concrete and unfinished? I need to find out what my best ceiling options are.


Also, excuse my ignorance, what does LF mean?


Thanks,

Berk


----------



## pepar




> Quote:
> Originally Posted by *(Berk)* /forum/post/15624369
> 
> 
> Thanks for your reply Pepar, I will finish the interior walls per normal standards.. framed, insulated, drywalled. As shown in the pictures, framing is already complete. Are you saying that without a finished ceiling I will need lots of bass traps or were you thinking all the walls were concrete and unfinished? I need to find out what my best ceiling options are.
> 
> 
> Also, excuse my ignorance, what does LF mean?
> 
> 
> Thanks,
> 
> Berk



With a concrete room, I think you will need lots of traps with or without the studded walls. The walls you describe will absorb some, but sound will pass through them to the concrete, reflect and then travel back through the walls. You might want to investigate the special construction materials available to help attenuate this.


LF = low frequency


----------



## (Berk)

I am planning to put floor to soffit corner bass traps in. Is it worth considering stuffing the soffit full of insulation (around the HVAC pipes) and then covering the front facing part with fabric?


Is there a spray on insulation that would work on the ceiling? What about egg carton shaped styrofoam?


----------



## whumpf




> Quote:
> Originally Posted by *pepar* /forum/post/15624621
> 
> 
> With a concrete room, I think you will need lots of traps with or without the studded walls. The walls you describe will absorb some, but sound will pass through them to the concrete, reflect and then travel back through the walls. You might want to investigate the special construction materials available to help attenuate this.
> 
> 
> LF = low frequency



How is this any different than all the basements here that have concrete block walls? Is poured concrete that much more reflective than block? What special construction materials besides DD ad GG?


----------



## Todd_zilla

Does anyone here know what the acoustically absorption properties are for upholstery foam rubber???


----------



## Todd_zilla

Gentlemen,


I am planning for a new theater and wanted to see if I am missing anything regarding sound absorption. The room is 18'1" long and 16'1" wide. The four walls are 6'6" high and then angle up at 45 degrees towards the ceiling. The ceiling is 11'2" high.


I plan on bass traps in the front corners, 2" OC 705 around the bottom 2 feet of the two side walls and the rear wall, and heavy insulation in the stage and riser to address the low end sound. I plan on 2" OC 703 on the two side walls and the rear wall on top of the OC 705 up to the 6'6" mark.


What else will I need? Do the slanted walls present any kind of unique problem?


----------



## will1383




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/15630378
> 
> 
> Does anyone here know what the acoustically absorption properties are for upholstery foam rubber???



It's rubber. Run. Run fast and far. Plastics and rubbers are naturally sound reflectors, even in a foam form. They work well to seal up doors, windows, HVACC and other possible sound leak areas, but they are pretty much useless for acoustical treatments.


That is, unless there are some new rubber-type materials which I am unaware of.


----------



## will1383

So, my problem is that I have a sound isolated room, which does really well, with the exception of LF. That stuff reverbarates pretty badly.


I have no acoustical treatments in my room yet, and the room's size/ratio is not one of the preferred acoustical dimensions - its 15'x14'x7'.


Now, I'm pretty confident I've addressed all of my possible flanks, so my guess is that it's simply the long wavelengths of the LF making their way through the walls, insulation and just bouncing every where.


So, I suppose my question is this:


When I add my acoustical treatments, including bass traps, will these help circumvent the excessive LF reverb through the rest of the house?


----------



## pepar




> Quote:
> Originally Posted by *whumpf* /forum/post/15629780
> 
> 
> How is this any different than all the basements here that have concrete block walls?



It is not.


----------



## will1383

And that has got to be the same problem I am having with my basement, but I'm already built with all my walls in, so I'm not left with too many options outside of acoustical treatments.


Guess this is the one thing I miscalculated or flat out missed. And now I have a pretty large LF problem through the house...


----------



## Terry Montlick




> Quote:
> Originally Posted by *will1383* /forum/post/15631093
> 
> 
> So, I suppose my question is this:
> 
> 
> When I add my acoustical treatments, including bass traps, will these help circumvent the excessive LF reverb through the rest of the house?



Sorry, but the answer is no.







This is a sound isolation problem, which cannot be substantially affected by acoustical treatment.


----------



## will1383




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15631296
> 
> 
> Sorry, but the answer is no.
> 
> 
> 
> 
> 
> 
> 
> This is a sound isolation problem, which cannot be substantially affected by acoustical treatment.



So, what can be done to decrease this? This is interesting because I followed all the guidelines regarding sound isolation and yet I still get this.










So, what did I miss??? What did the guys I spoke to miss?


I used whisper clips and acoustical caulk and green glue and the room-within-a-room technique... Hmph... What did I miss...


Or am I simply pushing more power through the room than the sound isolation can handle?


----------



## Terry Montlick




> Quote:
> Originally Posted by *will1383* /forum/post/15631359
> 
> 
> So, what can be done to decrease this? This is interesting because I followed all the guidelines regarding sound isolation and yet I still get this.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> So, what did I miss??? What did the guys I spoke to miss?



Low frequencies are always the hardest to isolate. Do you have your own construction pics of the sound isolation methods you used?


----------



## will1383




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15631490
> 
> 
> Low frequencies are always the hardest to isolate. Do you have your own construction pics of the sound isolation methods you used?



Yes I do. I performed all the construction myself as well, so I saw and understood all of the issues revolving around it.


----------



## Todd_zilla

Thank you Will...


Anybody have any thoughts about the room question I presented?


----------



## will1383




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/15633681
> 
> 
> Thank you Will...
> 
> 
> Anybody have any thoughts about the room question I presented?



I'm not an expert, nor even all that qualified to try and tackle that one. The ceiling... if it were me, I'd try to put in a flatter ceiling lower down, or talk to an acoustic engineer to see about diffusing up there. I really don't know other than that...


----------



## Todd_zilla

Terry,


Any thoughts?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/15634691
> 
> 
> Terry,
> 
> 
> Any thoughts?



None whatsoever.









It's the end of the day here, and my brain is fried!

I'll have a look tomorrow, though.


----------



## Todd_zilla

Thank you so much Terry... I find that a little vodka helps with that situation... Enjoy your evening my good man... ;-)


----------



## Terry Montlick




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/15635007
> 
> 
> Thank you so much Terry... I find that a little vodka helps with that situation...



Rats. I was planning on Bourbon.


----------



## David James

My theater is 16' wide and 19' long. We have one sofa about 12' back and behind that is a 37" high wall which goes about 10' across (see way cool drawing).

Behind the theater is the rest of my finished basement which extends another 30' or so.


Speakers won't move, sub may.


I will treat the front corners (floor to ceiling) and lower right corner (37") with bass traps. Should I be concerned about the wall behind the sofa?


Bonus question. The SPeakers are AV123 X-Statik open baffle speakers (tweeter and mids). I haven't read much about treating rooms with these types of speakers.


Thoughts?


Front

____________

|.................|

|..SP......SP..|

|.................|

|............sub|

|...-Sofa--....|

|.................|

......._______|


----------



## Screen Shot




> Quote:
> Originally Posted by *will1383* /forum/post/15553373
> 
> 
> I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.



Any update on this project? Pics?


I need something to copy.


----------



## Todd_zilla

This is a follow up and more info about the room I mentioned earlier.


In the planning stages for a new theater in a new house. Need some help and input for sound...


The new theater is already "built". The room is on the 2nd floor over a 3 car garage. Please see the pics, which includes a diagram of the rough space.


The floor space of the room is currently 19'4" wide (from the entry to the left wall)) and 20'6" long (from screen wall to rear). Because the current wall heights of the room are too low for what I want to do, I will be creating a "room within a room" effect, that will create some "unused" space that might be able to be used for sound absorption, but it will not be symmetrical.


All four walls will be 6'6" high and then begin angling at 45 degrees to a ceiling height of 11'2". By setting the wall height at 6'6" around the entire room, the room dimensions become 18'1" long and 16'1" wide. I'm including some pics. In the pics, where you see the boards taped to the wall, that is where the "false" wall height will be. The space behind those false walls is the unused space. On the screen and rear wall, I lose about 14" of floor space. On the left wall, I lose 3'3" of floor space. I plan on a 120" diagonal, non-acoustically transparent screen. I'll be running a 7.1 system. Infinite Baffle subwoofer that will have a large manifold opening the floor of my front stage and the manifold will actually be in my garage below the room. The manifold opening in the floor will span about 8' wide and will be centered in the front stage. Stand up floor speakers for L/R and each approximately 3' from the front wall and side walls. The center channel will rest on the stage floor and be aimed upwards.


I plan on using bass traps in all four corners, and either 2" acoustic foam or OC 703 at ear level and below. Perhaps do the bottom 2 feet of the 3 non-screen walls in 2 or more inches of OC 705 for even more evenly-distributed bass absorption. The room is carpeted. Will I need to put some sound absorption (either batting or 703 or 705) in the ceiling or on the slope walls going up to the ceiling? I can make the "inner" walls acoustically transparent and use the space behind the "inner" walls for sound absorption, but it won't be symmetrical. What are my other acoustic concerns for this room? I know angled walls are difficult to model...


Thanks in advance for the help guys... Todd


----------



## Todd_zilla

More pics...


----------



## will1383




> Quote:
> Originally Posted by *Screen Shot* /forum/post/15646527
> 
> 
> Any update on this project? Pics?
> 
> 
> I need something to copy.



I'm just getting the trim painted for the adjacent room and the door way sealed up. So, I have not yet started this phase of the project.


Due to a recent addition to the family, it is probably about a month away from being implemented.


Once I get a chance to get my theater build updated, I'll definitely post what I'm doing in there.


Sorry it's going to be so long, but having a new born in the house keeps you preoccupied.











I still need to figure out if there's anything I can do regarding my LF sound isolation problem. ALL other frequencies - you can't hear a thing... But I might have an idea of where my flank is that's allowing the sound to permeate through the house. I just need to do a few more tests and then come up with a solution - which might actually mean taking up the carpet and floor from the room above the ceiling.


----------



## will1383

Todd, if you haven't done so already, I suggest you start your own theater build thread to help isolate your specific issues, and then direct a bunch of us over there.







We're all here to help as we can.


----------



## will1383




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/15646662
> 
> 
> More pics...



Ah. Now I see what you mean. I would definitely look into using an AT screen and placing the speakers behind the screen and use that space to help with acoustics and asthetics.


----------



## Todd_zilla

Well, I thought I'd just bring up the acoustics part here in this thread since angled walls aren't really covered much... There will be a separate build thread.


----------



## will1383




> Quote:
> Originally Posted by *Todd_zilla* /forum/post/15649911
> 
> 
> Well, I thought I'd just bring up the acoustics part here in this thread since angled walls aren't really covered much... There will be a separate build thread.



OH, I'm not saying you shouldn't have done that. I'm simply stating there sounds like there's more to this build than just the angled ceiling, that's all.


----------



## Cheapbastard

Anyone know where to buy corning 703 in the san francisco bay area?


I'd like to get 12 sheets or less of the 1". I saw one place in oakland that sold it, but it was still cheaper on ebay even with shipping....


----------



## pepar




> Quote:
> Originally Posted by *Cheapbastard* /forum/post/15652335
> 
> 
> Anyone know where to buy corning 703 in the san francisco bay area?
> 
> 
> I'd like to get 12 sheets or less of the 1". I saw one place in oakland that sold it, but it was still cheaper on ebay even with shipping....


 http://www.spi-co.com/


----------



## Erik Westlund

This may be a helpful idea.

In my many years of experience with both home a/v and reading questions regarding How-To info. I've come to realize that there are some patterns of reoccurring questions and responses. Obviously there is not a clear answer to all questions. And all the answers could be debatable in various degrees. But my point remains the same...

I would like to recommend that someone with more time and knowledge put together a general (yet detailed) outline of the basics of how to build a "better" Home Theater room. Kind of like a bible in outline form.

One outline (In like a sideways-tree structure) could address a more appropriate construction from the ground up.

Yet another outline could mirror this, for others who have a room they would like to improve on (as in, a retrofit theme).

And thirdly. A glossary of what the abbreviations and it's definitions would be. So that they can be linked directly when a product, term or abbreviation is mentioned in these outlines. So people who would like to get a basic knowledge of what is involved and how to begin, whey would have a better understanding of how much work it would entail. Then they may plan accordingly. As well as anyone at any given stage in their progress can refer to this to see if they have to step back, sideways or forward with their processes to identify their options for working around a basic/ 'common' acoustic concern.

Again. With most situations there are some general parallels in acoustic properties that must be addressed before step 2-3-4... and so on. This would help me as well as some beginner. And likely minimize excessive forum static/noise.

Your thoughts?

ew


----------



## pepar




> Quote:
> Originally Posted by *Erik Westlund* /forum/post/15656165
> 
> 
> This may be a helpful idea.
> 
> In my many years of experience with both home a/v and in reading questions regarding How-To info. I've come to realize that there are some patterns of reoccurring questions and responses. Obviously there is not a clear answer to all questions. And all the answers could be debatable in various degrees. But my point remains the same...
> 
> I would like to recommend that someone with more time and knowledge put together a general (yet detailed) outline of the basics of how to build a "better" Home Theater room. Kind of like a bible in outline form.
> 
> One outline (In like a sideways-tree structure) could address a more appropriate construction from the ground up.
> 
> Yet another outline could mirror this, for others who have a room they would like to improve on (as in, a retrofit theme).
> 
> And thirdly. A glossary of what the abbreviations and it's definitions would be. So that they can be linked directly when a product, term or abbreviation is mentioned in these outlines. Thereby people who would like to get a basic knowledge of what is involved, how to begin, and how much work it would entail for them to plan on a direction they may want to take with their ideas from there. And anyone at any stage in their progress can refer to this to see if they have to step back, sideways or forward with their processes and to identify other options for working around a basic/ 'common' acoustic concern.
> 
> Again. With most situations there are some general parallels in acoustic properties that must be addressed before step 2-3-4... and so on. This would help me as well as some beginner.
> 
> Your thoughts?
> 
> ew



Those here with the knowledge and experience who could put something like that together are professional consultants, with "professionals" meaning "they work for money." That they answer questions at all for free is greatly appreciated. I am afraid that you will need to research this material on your own - like the rest of us have - or step up and hire a pro.


----------



## will1383

Whats really interesting is that the more I learn, the more apt I am to hire a professional.


Maybe someday when my company takes off and I'm doing a redesign.


----------



## 04FLHRCI

I agree with pepar; I just returned home from spi's KC location with a truckload (384sq.ft.) of 703. Friendly folks with great prices.


Regards,


Larry




> Quote:
> Originally Posted by *pepar* /forum/post/15654750
> 
> http://www.spi-co.com/


----------



## David James




> Quote:
> Originally Posted by *04FLHRCI* /forum/post/15657424
> 
> 
> I agree with pepar; I just returned home from spi's KC location with a truckload (384sq.ft.) of 703. Friendly folks with great prices.
> 
> 
> Regards,
> 
> 
> Larry



That's a bunch of 703







Just curious, what did you pay. I did finally find a place that charged $1.56/sqft.


People need to call first. The Denver SPI place didn't even sell OC


----------



## CJO




> Quote:
> Originally Posted by *Erik Westlund* /forum/post/15656165
> 
> 
> ...I would like to recommend that someone with more time and knowledge put together a general (yet detailed) outline of the basics of how to build a "better" Home Theater room. Kind of like a bible in outline form.



It isn't quite what you've asked, but I tried to outline the links to all of the background material I used in making the decisions for my theater in my first couple posts in my theater build. Maybe it will help.


CJ


----------



## airbeagle

I know this is probably a real dumb questions for a lot of you, but I'm going to ask anyway. I've been reading a lot about OC 703 and Linacoustics and others in the forum. I was wondering if there was something comparable that I can just pick up at Home Depot or Lowes. Or something a little less costly. My space is approximately 24x17x8 and all this adds up. I'm building a theater, it doesn't have to be perfect, but I'd like it to be reasonably nice without blowing my budget. Anyone have any suggestions? I see that most people only go up about 3 feet with the fiberglass insulation, what do you recommend above that? Any help will be appreciated. I'll be honest, I don't know what I'm doing, I'm not real knowledgeable in acoustics, I didn't even think about the insulation when I started, but I'm determined to make a nice theater. Thanks in advance and I apologize if this question sucks.


----------



## 04FLHRCI

David,


I'm almost ashamed to share; I paid $.85/sqft for the 703 (705 was $1.50/sqft). This is their standard price; they didn't have enough in stock, so i had to wait a week for the OC truck to come in.


Larry




> Quote:
> Originally Posted by *David James* /forum/post/15657545
> 
> 
> That's a bunch of 703
> 
> 
> 
> 
> 
> 
> 
> Just curious, what did you pay. I did finally find a place that charged $1.56/sqft.
> 
> 
> People need to call first. The Denver SPI place didn't even sell OC


----------



## csamos




> Quote:
> Originally Posted by *04FLHRCI* /forum/post/15665231
> 
> 
> David,
> 
> 
> I'm almost ashamed to share; I paid $.85/sqft for the 703 (705 was $1.50/sqft). This is their standard price; they didn't have enough in stock, so i had to wait a week for the OC truck to come in.
> 
> 
> Larry



Wow, that's a great price. The best I found around Austin was $1.30/sqft for the 703-plain, and $2.94/sqft for the 705-FRK. 705-plain was a little cheaper at $2.36sqft, but I needed the foil backed 705 for my bass traps.


----------



## pepar

703 comes in a few different thicknesses. Just stating a square foot price without the thickness is like saying that my theater is 20 feet.


----------



## Terry Montlick

OC 703 is 3pcf fiberglass, and the generic name for this is "Type 300." The US manufacturers of fiberglass are Knauf, Owens Corning, Johns Manville, and CertainTeed. 3pcf fiberglass from any of these manufacturers is acoustically equivalent.


Regards,

Terry


----------



## csamos




> Quote:
> Originally Posted by *pepar* /forum/post/15665503
> 
> 
> 703 comes in a few different thicknesses. Just stating a square foot price without the thickness is like saying that my theater is 20 feet.



Ah yes, that's why I saw some different prices, but I was just thinking about the 2" boards I was looking at and got.


----------



## pepar




> Quote:
> Originally Posted by *csamos* /forum/post/15665621
> 
> 
> Ah yes, that's why I saw some different prices, but I was just thinking about the 2" boards I was looking at and got.



Different densities and different thicknesses all, I believe, in the 24" x 48" size. And, IIRC, it was cheaper to buy two 2" panels than one 4" panel.


----------



## csamos




> Quote:
> Originally Posted by *pepar* /forum/post/15665652
> 
> 
> Different densities and different thicknesses all, I believe, in the 24" x 48" size. And, IIRC, it was cheaper to buy two 2" panels than one 4" panel.



Yeah, I bought all 2" thick panels and doubled them up where I needed 4" thick panels, like for the bass traps in the corners especially.


Really, for how little I paid, plus my time, the sound improvement is quite dramatic. I'm glad I finally did it.


----------



## ScruffyHT




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15665599
> 
> 
> OC 703 is 3pcf fiberglass, and the generic name for this is "Type 300." The US manufacturers of fiberglass are Knauf, Owens Corning, Johns Manville, and CertainTeed. 3pcf fiberglass from any of these manufacturers is acoustically equivalent.
> 
> 
> Regards,
> 
> Terry



Terry ... what would the JM 1" Linacoustic equivalent be from those other 3 manufacturers ? ... I am having a helluva time trying to find it in my market


Thanks


----------



## David James

It seems one of the most popular size for acoustic panels is 2'x4'. I'm guessing, but I suspect it's because 703 (and eq.) comes in that size. I'm using Bonded Logic's UltraTouch which comes in 94" batts. Can someone comment on the value of using larger panels, i.e. 2'x6' or up to the full length, 94", other then aesthetics.


----------



## Terry Montlick




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/15666197
> 
> 
> Terry ... what would the JM 1" Linacoustic equivalent be from those other 3 manufacturers ? ... I am having a helluva time trying to find it in my market
> 
> 
> Thanks



Linacoustic is a trade name which JM uses to cover a range of their fiberglass duct liner products. The type usually used by forum members is Linacoustic RC (Reinforced Coating), which comes in rolls and has a dark color.


The RC part is kind of their "secret sauce," and JM doesn't like to give out a lot of specifics on this product, like its density. But density is found by simply dividing the weight of a roll by coverage area times thickness, and that makes this stuff 2.25 pcf.







I wouldn't get hung up on 2.25 pcf vs. 3 pcf. From my own analysis, there's no significant difference in sound absorption between the two.


----------



## Ethan Winer




> Quote:
> Originally Posted by *David James* /forum/post/15666281
> 
> 
> Can someone comment on the value of using larger panels, i.e. 2'x6' or up to the full length, 94", other then aesthetics.



The more total corner surface you cover, the better. Always. You can do this with multiple 2x4 foot panels, or with larger single panels. No difference.


--Ethan


----------



## David James




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15674494
> 
> 
> The more total corner surface you cover, the better. Always. You can do this with multiple 2x4 foot panels, or with larger single panels. No difference.
> 
> 
> --Ethan



Thanks Ethan, I'm doing floor in the ceiling corners, I'm referring to first reflection points on the side walls. Would 2'x6' (or larger) be better then 2'x4'?


Thanks again for you help.


----------



## pepar




> Quote:
> Originally Posted by *David James* /forum/post/15674680
> 
> 
> Thanks Ethan, I'm doing floor in the ceiling corners, I'm referring to first reflection points on the side walls. Would 2'x6' (or larger) be better then 2'x4'?
> 
> 
> Thanks again for you help.



I sized mine to only cover the first reflection points of the L, C & R for all six of my seating positions. If further treatment is required to optimize RT60, it can be added.


Just my $.02.


----------



## David James




> Quote:
> Originally Posted by *pepar* /forum/post/15674755
> 
> 
> I sized mine to only cover the first reflection points of the L, C & R for all six of my seating positions. If further treatment is required to optimize RT60, it can be added.
> 
> 
> Just my $.02.



I'm sorry if my question isn't clear, but I'm not following. How big did you determine how big your reflection points were? I understand the mirror trick to discover where on the wall the reflection point would be, but what determines the vertical size of the panel?


----------



## will1383




> Quote:
> Originally Posted by *David James* /forum/post/15675701
> 
> 
> I'm sorry if my question isn't clear, but I'm not following. How big did you determine how big your reflection points were? I understand the mirror trick to discover where on the wall the reflection point would be, but what determines the vertical size of the panel?



Listening location height. So, if your ear level is between 40" and 60" from the floor, you want to build a panel that covers from say, 36" to 66" vertically to provide the most coverage.


There are also approaches where some engineers prefer to deaden EVERYTHING below the listener's ear level, and then use targeted reflection panels as you are speaking.


So, for us DYI'ers, we have to simply decide what direction we want to go in, and kinda hope we are going to get what we want in the end. Unless you want to spend lots of time doing your own room measurements, etc.


I have a relatively small room, with my entry on the same wall as the screen. I have decided to take the approach of deadening the entire front wall - including the door and behind the screen (I'm doing an AT screen for this reason). Then I'll take measurements and apply the rest of the room as I can.


I am not going to treat the entire lower part of my walls with absorbant materials due to the decor my wife and I want, and what we are willing to live with given our environment... Perfect? No, but it was either that, or hire an engineer to come in an design it all for us and work with us through the entire process, something we did not allocate budgeting for.


If I build another room, however, I will seek professional assistence outside of these forums and researching I did myself and some of the awesome professionals here who I have spoken with.


I hope this helps a little bit.


bty, I found my Low Frequency flank. It's a cold air return in my ceiling that vibrates like hell. I can't get at it from the basement now because of the floating ceiling, but since I'm tearing up the floor in that room above (going to hard wood instead of carpet) I'm going to rip up the floor to access and address that cold air return and try to address the vibrating wall that's right there as well. I also have acoustical floor matting (very, very dense) that I might put under the Hard wood for additional sound control... That's about the best I'm going to be able to do..


----------



## pepar




> Quote:
> Originally Posted by *David James* /forum/post/15675701
> 
> 
> I'm sorry if my question isn't clear, but I'm not following. How big did you determine how big your reflection points were? I understand the mirror trick to discover where on the wall the reflection point would be, but what determines the vertical size of the panel?



The panel size and location are all a function of the locations of the speakers and the seats. Think in 3D. The mirror "trick" can define the outline on the panels, but I more or less used my skill at shooting pool. (The angle of the incidence = the angle of reflection.) Specifically, the vertical size of the panel is determined by the height of the speakers and the height of the listeners. If the speakers and the listeners are ALL ON THE SAME PLANE, then the panel will be pretty darn skinny in the vertical dimension.


Visualize the problem and the solution will come to you.


----------



## will1383

Good point on the plane of the speakers and the listeners. Thinking about how I was going about handling it, that's exactly what I was taking into account without actually pinning exactly what I was doing.


----------



## David James

will and pepar - thanks for your patience and explanations, they have been very helpful.


----------



## Ethan Winer




> Quote:
> Originally Posted by *David James* /forum/post/15674680
> 
> 
> Would 2'x6' (or larger) be better then 2'x4'?



Larger is usually better. It's not a single reflection point, of course, but an area. I suggest using a mirror to identify all places where either loudspeaker is visible. Then extend the area at least a foot in all directions. If the room is too live generally, you could go even larger.


--Ethan


----------



## will1383




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15677380
> 
> 
> Larger is usually better. It's not a single reflection point, of course, but an area. I suggest using a mirror to identify all places where either loudspeaker is visible. Then extend the area at least a foot in all directions. If the room is too live generally, you could go even larger.
> 
> 
> --Ethan



Ya, I know in my case my room is very lively, but I'm not going to be totally sure what I have to do until I get the front wall and screen together. Then I'll measure and see where things stand. My guess is I"ll ahve to go pretty heavy on first and second reflection points, and I know I need some major base trapping, which is going to be VERY difficult in the front of the room due to how close everything is.


Actually, that's a question I have with regards to base traps. I'm going to be hard pressed to fit anything in the front of the room, other than my speaker stands which double as bass traps (can fill them with sand). With this being the case, would you suggest moving the subwoofer to the rear of the room where I'll have a couple of bass traps in the corners (I'm not sure what I'll have there at this point, I just know I will)?


Or should I just take measurements with the woofer in both places and see which comes out a little flatter and roll with that?


Because of this, would you also recommend against a second subwoofer?


----------



## 04FLHRCI

My, what a disposition you have there; this was 2" thick 2' x 4' sheets... I'll remember NOT to include build pictures within this thread











> Quote:
> Originally Posted by *pepar* /forum/post/15665503
> 
> 
> 703 comes in a few different thicknesses. Just stating a square foot price without the thickness is like saying that my theater is 20 feet.


----------



## David James

Here are some pictures of the UltraTouch Cotton attached to the walls with my specially fabricated acoustic panel attachment devices.







The corner traps are 33" across, 24" along the walls.

















Here is a view from the screen back through the theater and on into the pool room and bar area. I'm not sure what I should do if anything on the half wall and the small columns.


----------



## Dennis Erskine

As an FYI, there is a new product (a couple actually) from Quest Acoustical Interiors ( www.questai.com ), ... no I don't work for them.


Perf-Sorber is a combination absorber/diffuser in a single fiberglass panel. An excellent early reflection point product speakers with good off axis response. Also, a good choice around surround speakers. The other (I forget their trade name) is a product with very good absorption down to 150Hz.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15682827
> 
> 
> As an FYI, there is a new product (a couple actually) from Quest Acoustical Interiors ( www.questai.com ), ... no I don't work for them.
> 
> 
> Perf-Sorber is a combination absorber/diffuser in a single fiberglass panel. An excellent early reflection point product speakers with good off axis response. Also, a good choice around surround speakers. The other (I forget their trade name) is a product with very good absorption down to 150Hz.



Thanks, but I could not find the Perf-Sorber.


----------



## Ethan Winer




> Quote:
> Originally Posted by *will1383* /forum/post/15677451
> 
> 
> I'm going to be hard pressed to fit anything in the front of the room



Wall-floor and wall-ceiling corners are just as good as wall-wall corners.



> Quote:
> my speaker stands which double as bass traps (can fill them with sand).



A tube filled with sand is _not_ a bass trap.



> Quote:
> would you suggest moving the subwoofer to the rear of the room where I'll have a couple of bass traps in the corners



Sub location and bass trap location are not really related. If you can post a photo of your room I may be able to suggest something.



> Quote:
> would you also recommend against a second subwoofer?



I do fine with one killer SVS sub and a huge amount of bass trapping, but some people are happy with two subs.


--Ethan


----------



## will1383




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15685307
> 
> 
> Wall-floor and wall-ceiling corners are just as good as wall-wall corners.
> 
> 
> 
> 
> A tube filled with sand is _not_ a bass trap.
> 
> 
> 
> 
> Sub location and bass trap location are not really related. If you can post a photo of your room I may be able to suggest something.
> 
> 
> 
> 
> I do fine with one killer SVS sub and a huge amount of bass trapping, but some people are happy with two subs.
> 
> 
> --Ethan



I have family down your way, and I think we are going to visit sometime in April. I should try and see if I can make an appointment to come and visit you.


Here's a basic layout of my room:












But, it is Tight around the screen and such. There's very little room in the front for bass traps.


Funny, I thought that a sand filled tube would suffice as partly a bass trap, but, I figured that something wasn't quite right about that. The two rear corners, again are going to be pretty tight, but I have more room to work with in those than in the front...


I might put 4" of 703 on the front wall instead of 2 just to help with the lower frequency absorbtion... Thoughts regarding that?


Or should I really take the time to take all the measurements of the room before doing anything?


Also, where those sconces are there are going to be 4 Cherry columns. They are wood, would mass loading the inside of them help absorb some of the low frequencies? They are not at the 1st and 2nd reflection points.


----------



## Dennis Erskine




> Quote:
> Thanks, but I could not find the Perf-Sorber



Call them. It may not be up on the website yet. Works very nicely.


----------



## sound dropouts

I am hoping to make a theater in the upstairs room of a house. The roof slants into the room, creating an odd shape. I am unsure how to acoustically treat the room. Attached is a rough drawing of what I hope the front will look like...where should I put acoustic treatemnts? Should I put them on the slanted parts as well?


----------



## Ethan Winer




> Quote:
> Originally Posted by *will1383* /forum/post/15685754
> 
> 
> I thought that a sand filled tube would suffice as partly a bass trap, but, I figured that something wasn't quite right about that.



There's an article on the DIY TV Network site that shows how to make a "bass trap" from sand in a cardboard tube. That article is the laughing stock of the acoustics industry. I even wrote to them and explained (nicely), but they never replied and the article was still there the last time I checked.



> Quote:
> I might put 4" of 703 on the front wall instead of 2 just to help with the lower frequency absorbtion.



Sure, that can only help. Especially if it's near wall-wall, wall-floor, and/or wall-ceiling corners.



> Quote:
> They are wood, would mass loading the inside of them help absorb some of the low frequencies?



Not likely.


--Ethan


----------



## (Berk)

I previously explained my concrete bunker under the garage that I am currently working on. There is only one wall that is shared with the rest of the home, the other 3 walls are fully below ground level the only thing on the otherside of them is dirt.


If I'm not worried about sound isolation, only a good sounding room, wouldn't it also work to just not drywall the bottom 48" of all the walls? Could I shove regular insulation in there, then some linacoustic (if it is needed?) and then fabric? Then I only have to drywall the top portion.


The one shared wall on the other side of the 8 inch concrete wall is 2X6 framed, and drywalled too.


Also, can anyone tell me if eggcarton shaped foam is a good idea to put on my sloped concrete ceiling?


Thanks,

Berk


----------



## Ethan Winer




> Quote:
> Originally Posted by *(Berk)* /forum/post/15699256
> 
> 
> If I'm not worried about sound isolation, only a good sounding room, wouldn't it also work to just not drywall the bottom 48" of all the walls?



Drywall, cement, it's all the same - reflective. If you want the room to sound good what you really need are corner bass traps, plus absorbers at the side-wall and ceiling reflection points.



> Quote:
> can anyone tell me if eggcarton shaped foam is a good idea to put on my sloped concrete ceiling?



It depends on the quality and thickness of the foam. Generally speaking, better treatments are made from rigid fiberglass.


--Ethan


----------



## (Berk)




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15702270
> 
> 
> Drywall, cement, it's all the same - reflective. If you want the room to sound good what you really need are corner bass traps, plus absorbers at the side-wall and ceiling reflection points.
> 
> 
> 
> 
> It depends on the quality and thickness of the foam. Generally speaking, better treatments are made from rigid fiberglass.
> 
> 
> --Ethan




So if drywall and cement are both reflective, there is no benefit to drywall the areas that will be covered up with treatments anyways?


Okay thanks, that will save me some time and money.


----------



## eugovector




> Quote:
> Originally Posted by *(Berk)* /forum/post/15702454
> 
> 
> So if drywall and cement are both reflective, there is no benefit to drywall the areas that will be covered up with treatments anyways?
> 
> 
> Okay thanks, that will save me some time and money.



Keep in mind that you want the room to be insulated for heat/ac as well as sound. Don't want to be sweating/freezing while you're watching movies.


----------



## ScruffyHT




> Quote:
> Originally Posted by *(Berk)* /forum/post/15699256
> 
> 
> If I'm not worried about sound isolation, only a good sounding room, wouldn't it also work to just not drywall the bottom 48" of all the walls? Could I shove regular insulation in there, then some linacoustic (if it is needed?) and then fabric? Then I only have to drywall the top portion.
> 
> 
> The one shared wall on the other side of the 8 inch concrete wall is 2X6 framed, and drywalled too.
> 
> Thanks,
> 
> Berk



Are you going to have the room inspected by the city ? ( electrical etc ? )


----------



## (Berk)




> Quote:
> Originally Posted by *ScruffyHT* /forum/post/15702583
> 
> 
> Are you going to have the room inspected by the city ? ( electrical etc ? )



No, I'm not planning having inspections done.


----------



## (Berk)




> Quote:
> Originally Posted by *eugovector* /forum/post/15702563
> 
> 
> Keep in mind that you want the room to be insulated for heat/ac as well as sound. Don't want to be sweating/freezing while you're watching movies.



I'm definitely going to insulate still, but I'm thinking of saving the bother of putting drywall on top of the insulation, only to add more insulation for accoustics.


----------



## Ethan Winer




> Quote:
> Originally Posted by *(Berk)* /forum/post/15702454
> 
> 
> So if drywall and cement are both reflective, there is no benefit to drywall the areas that will be covered up with treatments anyways?



Yes, assuming you mean using Liquid Nails etc to glue drywall flat onto the cement. In that case it's bunch of work for no acoustic gain. But making a new stud wall inside the cement wall can help (a little) with acoustics, and that can add thermal insulation too as eugovector said.


--Ethan


----------



## (Berk)




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15709021
> 
> 
> Yes, assuming you mean using Liquid Nails etc to glue drywall flat onto the cement. In that case it's bunch of work for no acoustic gain. But making a new stud wall inside the cement wall can help (a little) with acoustics, and that can add thermal insulation too as eugovector said.
> 
> 
> --Ethan



No, I have a 4 concrete walls that I've framed a new stud walls inside which will be fully insulated.


I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.


----------



## pepar




> Quote:
> Originally Posted by *(Berk)* /forum/post/15710971
> 
> 
> No, I have a 4 concrete walls that I've framed a new stud walls inside which will be fully insulated.
> 
> 
> I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.



Resale value?


----------



## will1383




> Quote:
> Originally Posted by *(Berk)* /forum/post/15710971
> 
> 
> No, I have a 4 concrete walls that I've framed a new stud walls inside which will be fully insulated.
> 
> 
> I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.



I guess in theory you could, but you are only going to be saving maybe $100-150 on a several $1000's build. IMO, it's not worth saving in this case. Build a studded wall inside the concrete walls, and decouple that wall. Put Drywall on the whole thing, and then go from there. It'll be the best bang for the buck.


When I did this, I actually glued insulation onto my concrete walls, to help with both environmental and acoustics. Whether or not it made a difference acoustically, I have no idea.


----------



## Ethan Winer




> Quote:
> Originally Posted by *(Berk)* /forum/post/15710971
> 
> 
> I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.



In that case you'll do well to pack the entire space behind the drywall with fluffy fiberglass. Leaving off the bottom sheet rock will help _a lot_ acoustically, because that gives substantial bass trapping along all the wall-floor corners. I agree with pepar about resale value, though maybe the next owner will want a good sounding room too?


--Ethan


----------



## Erik Westlund




> Quote:
> Originally Posted by *pepar* /forum/post/15656232
> 
> 
> Those here with the knowledge and experience who could put something like that together are professional consultants, with "professionals" meaning "they work for money." That they answer questions at all for free is greatly appreciated. I am afraid that you will need to research this material on your own - like the rest of us have - or step up and hire a pro.



Thanks Pepar for your response. But I feel you have misinterpreted my message a little. It would not intend to weaken the consumer/client relations. I think it would enrich it.


I am in the A/V retail sales industry. And I have been for years. I see with both a consumer-client point of view (it's my hobby) AS WELL as the sales side of things. I always appreciate a more knowledgeable client when I meet one. It makes for a better level of communication. Even if they have the basics down... just a little. I can better understand their motives and interests. It also makes their efforts easier, as well. Since this is a technology based language. It seems obvious to me that one must understand the basics before they can communicate with a more experienced individual.


Often times, a client may not have the full or correct information from what they have learned. But that's OK if they have not executed that idea yet. After talking with a professional, they will be more aware and appreciative of their help and knowledge. They will realize that there is a whole lot more to know. When the client has taken the initiative to attain some knowledge on their own. They then realize it can't be done on their own if they want to do it right and/or done in a reasonable amount of time.


With the intent of this "outline- a/v bible", most of these basics can be covered. This should minimize a level of forum redundancy and advance beginners to intermediate in little time.


no?


----------



## pepar




> Quote:
> Originally Posted by *Erik Westlund* /forum/post/15725382
> 
> 
> Thanks Pepar for your response. But I feel you have misinterpreted my message a little. It would not intend to weaken the consumer/client relations. I think it would enrich it.
> 
> 
> I am in the A/V retail sales industry. And I have been for years. I see with both a consumer-client point of view (it's my hobby) AS WELL as the sales side of things. I always appreciate a more knowledgeable client when I meet one. It makes for a better level of communication. Even if they have the basics down... just a little. I can better understand their motives and interests. It also makes their efforts easier, as well. Since this is a technology based language. It seems obvious to me that one must understand the basics before they can communicate with a more experienced individual.
> 
> 
> Often times, a client may not have the full or correct information from what they have learned. But that's OK if they have not executed that idea yet. After talking with a professional, they will be more aware and appreciative of their help and knowledge. They will realize that there is a whole lot more to know. When the client has taken the initiative to attain some knowledge on their own. They then realize it can't be done on their own if they want to do it right and/or done in a reasonable amount of time.
> 
> 
> With the intent of this "outline- a/v bible", most of these basics can be covered. This should minimize a level of forum redundancy and advance beginners to intermediate in little time.
> 
> 
> no?



Nice thoughts, but it would still be a lot of work on a complex subject with many aspects that lack 100% consensus . . with no immediate . . and perhaps simply no . . return.


You're in marketing, aren't you?


----------



## Triaxtremec

Where is a great place to get rigid fiberglass so I may make my own panels? Also are foam panels bad to use?


----------



## elee532




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15682827
> 
> 
> Perf-Sorber is a combination absorber/diffuser in a single fiberglass panel. An excellent early reflection point product speakers with good off axis response. Also, a good choice around surround speakers. The other (I forget their trade name) is a product with very good absorption down to 150Hz.



So, I was thinking about trying these, or maybe just a plain old absorption panel, at my side reflection points. However, my room has a 6" ledge and then a window about 4' up the wall. The right side wall has no similar constraints. How would I position a panel on this wall?


Here are some photos (see particularly the last one of the bunch):
http://www.avsforum.com/avs-vb/showp...postcount=2825 


Thanks!


----------



## Erik Westlund




> Quote:
> Originally Posted by *pepar* /forum/post/15726365
> 
> 
> Nice thoughts, but it would still be a lot of work on a complex subject with many aspects that lack 100% consensus . . with no immediate . . and perhaps simply no . . return.
> 
> 
> You're in marketing, aren't you?



Perhaps you are right. There are a lot of good books out there to begin with, as well.


p.s. no. I'm not in marketing.









p.s. I've been reading the latest posts. I just would like to throw this out.

If anyone is thinking of putting up a lot of sound treatment on the walls. Be careful of what type of material you use to keep the maintenance low. Mainly mold. For instance. If you live in a humid place and you want to put up something like cotton in a basement wall, consider your options first. You also might want to keep this spider free, too.

ew


----------



## bravo36




> Quote:
> Originally Posted by *Triaxtremec* /forum/post/15730571
> 
> 
> Where is a great place to get rigid fiberglass so I may make my own panels? Also are foam panels bad to use?



Here's where I got mine in Dallas: http://www.spi-co.com/index.html 


And guess what...they have a location in Omaha: SPI (Specialty Products and Insulation Co.)


5010 I Street

Omaha, NE***68117

402-827-3880

402-827-3882 FAX
[email protected] 


Great, friendly folks to deal with at my location. I bought 1 1/2" 3# ridgid panels for about $90.00/case (16-2x4 sheets). Worked like a champ.


----------



## AnthemAVM

Anyone have a good place to buy Guilford of Maine fabric?


I have some GIK panels that need to be recovered in a new color.


thanks


----------



## (Berk)




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15718854
> 
> 
> In that case you'll do well to pack the entire space behind the drywall with fluffy fiberglass. Leaving off the bottom sheet rock will help _a lot_ acoustically, because that gives substantial bass trapping along all the wall-floor corners. I agree with pepar about resale value, though maybe the next owner will want a good sounding room too?
> 
> 
> --Ethan



Thanks Ethan,


I'm more interested in the accoustic results than the resale value, but I'm not sure how anyone would notice that there isn't any sheetrock behind the bottom section if the fluffy fiberglass is covered with fabric wrapped rigid fibreglass panels. What do you think about using painted Tectum board for the bottom section instead of the rigid fibreglass? It would still be on top of the fluffy fibreglass.


Thanks for your input.


----------



## pepar




> Quote:
> Originally Posted by *AnthemAVM* /forum/post/15740412
> 
> 
> Anyone have a good place to buy Guilford of Maine fabric?
> 
> 
> I have some GIK panels that need to be recovered in a new color.
> 
> 
> thanks



The best price I had found when I built my treatments is here . Every online seller that I found was very "proud" of this product (read: it ain't cheap), but it works and has safety aspects that stuff from the local fabric shop lacks.


----------



## nathan_h




> Quote:
> Originally Posted by *AnthemAVM* /forum/post/15740412
> 
> 
> Anyone have a good place to buy Guilford of Maine fabric?
> 
> 
> I have some GIK panels that need to be recovered in a new color.
> 
> 
> thanks



GIK sells GOM fabric separately from the panels for about $15 per yard which seems to be the standard price.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/15742997
> 
> 
> GIK sells GOM fabric separately from the panels for about $15 per yard which seems to be the standard price.



I'm pretty sure that I paid substantially less at the place I linked, but that was some years ago. The poster should compare prices for himself.


----------



## nathan_h

Looks like the same price, these days. I'd love to find a lower priced source, too, since I have some substantial areas to cover but have held off due to the price.


----------



## SteveMo




> Quote:
> Originally Posted by *SteveMo* /forum/post/15494097
> 
> 
> To continue where I left off, I have thought of way to keep the height the same. I could use some string, thread, or line with some push pins on each wall to the side of the seats using a level to check it was correct then mark have correct height to measure at. I could also mark using some tape or marker on the string or line to mark exactly where the RS meter would be for each test.
> 
> 
> I have some questions first.
> 
> 
> Do I wait until I have my left corner treated same as the right before I check these panels at different locations? I'm worried that it will make my measurements more difficult to look at. I have an idea of what the left corner not having the additional trap will cause, so should I just start with the panels and keep that in mind when looking at results? I am aware of what modes this effects.
> 
> 
> I have another Pillar trap for the left corner and another pair of GIK 244's on the way also so I am wondering if I should just wait to measure when I have these also.
> 
> 
> Another thing I am concerned with is that if I am moving my speakers out to the center of the room that is going to be a problem I would think having my screen area left untreated. Should I just measure the near field at the location there are at closer to panels and corner traps? I measure at 1 meter or slightly further with the mic aimed between the tweeter and the higher speaker driver?



Still at it. Here are the left and right speaker measurements again.


----------



## Ethan Winer




> Quote:
> Originally Posted by *(Berk)* /forum/post/15741369
> 
> 
> What do you think about using painted Tectum board for the bottom section instead of the rigid fibreglass? It would still be on top of the fluffy fibreglass.



Sure, or homasote etc works well too and can be painted. Bass goes right through into the fiberglass behind.


--Ethan


----------



## (Berk)




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/15744704
> 
> 
> Sure, or homasote etc works well too and can be painted. Bass goes right through into the fiberglass behind.
> 
> 
> --Ethan




So, just fibreglass in between the studs and painted homesote or tectum on top of that will give me better bass control that covering with sheetrock?


If I did that along the bottom 48" of all walls, and sheetrocked the top, would that be a good balance of absorbtion and reflection?


----------



## mtbdudex

Do you have any before and after H20 plots to show diff in decay time?

I'm also looking at adding panels and am interested in others results, compared to this chart from Rives site http://www.positive-feedback.com/Issue12/rives2.htm 











> Quote:
> Originally Posted by *csamos* /forum/post/15561806
> 
> 
> After having my theater for 5 years now, I finally got around to analyzing first reflection points and building/mounting acoustic panels. I used 2" thick OC 703 with 2" air gaps for the acoustic panels. I also used 4" thick OC 705 for several corner bass traps. The improvement in the audio is amazing. I've only auditioned a few movie scenes so far, but the difference is tremendous. Even my girlfriend (she's not a video/audiophile) thought the asteroid chase scene in Star Wars Episode II was incredible sounding.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here are some panels on one wall:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I mounted 4 on the ceiling in front the projector. You can also see a bass trap at the ceiling, as well as part of an acoustic panel to the right of the component cabinet.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> There are bass traps in the front corners of the room and along the right side at the ceiling. This was before the acoustic panels were installed, and all mounting hardware has been painted black as well, so it's no longer visible.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It was a much longer task than I anticipated, but I'm so glad I finally did it.


----------



## Ethan Winer




> Quote:
> Originally Posted by *(Berk)* /forum/post/15746102
> 
> 
> So, just fibreglass in between the studs and painted homesote or tectum on top of that will give me better bass control that covering with sheetrock?



Yes.



> Quote:
> If I did that along the bottom 48" of all walls, and sheetrocked the top, would that be a good balance of absorbtion and reflection?



Hard to say without seeing the rest of the room. Most HT rooms benefit from more absorption than less. So if it were me I'd have bass traps in the upper corners of the walls too.


--Ethan


----------



## HTPonte

I am need of some help I am not sure if I calculated my first reflection surface correctly and I may need to move my light positions. I have a small room 15' (false wall) x 12' 4. I am borrowing the Arthouse design alternating wood panels 2' 2 x 4' and OC 703 same with 3.5" gap. I will treat behind the screen with linacoustic. I calculated my first reflection surface using info on Ethan's website at around 1' 9.


Speakers are about 1' 5 from the wall.

Offset I am about 6' from the same wall

I estimated the distance from the speaker to me ear at 8'. My stage is about 9' from false wall.


If I estimated correct I only have about 1' of OC in front of the stage before the wood panel starts. Do I need to shift me center wall light back another 1'? In attached Picture lines indicate light placement and center of wood panel. Thanks for your help in advance I was hoping to wire this weekend.


----------



## AnthemAVM




> Quote:
> Originally Posted by *HTPonte* /forum/post/15763129
> 
> 
> I am need of some help I am not sure if I calculated my first reflection surface correctly and I may need to move my light positions. I have a small room 15' (false wall) x 12' 4. I am borrowing the Arthouse design alternating wood panels 2' 2 x 4' and OC 703 same with 3.5" gap. I will treat behind the screen with linacoustic. I calculated my first reflection surface using info on Ethan's website at around 1' 9.
> 
> 
> Speakers are about 1' 5 from the wall.
> 
> Offset I am about 6' from the same wall
> 
> I estimated the distance from the speaker to me ear at 8'. My stage is about 9' from false wall.
> 
> 
> If I estimated correct I only have about 1' of OC in front of the stage before the wood panel starts. Do I need to shift me center wall light back another 1'? In attached Picture lines indicate light placement and center of wood panel. Thanks for your help in advance I was hoping to wire this weekend.



Is the room built? If so, use the mirror method to find your first reflection points.


----------



## HTPonte

No it is just framed out.


----------



## Dennis Erskine

[qutoe]Should I just measure the near field at the location there are at closer to panels and corner traps? I measure at 1 meter or slightly further with the mic aimed between the tweeter and the higher speaker driver?[/quote]

The primary purpose for near field measurements is to measure the speaker's performance eliminating room interactions. To determine the impact of room treatments, you should be measuring (and listening) from the seating locations.


----------



## SteveMo

Thanks Dennis. I will be getting some mineral wool for the back wall and probobly some more bass traps for the side walls. I would then have a total of 6 for the side walls not counting the one on the door already. My projector conked out so until we get the new one I will be moving the front left and right speakers away from the walls further now. That 84Hz second order width mode and the 85Hz first order length mode are a pain to deal with.


----------



## da crusher

I've read for days concerning various DIY bass traps. Tubes, resonating panels, Helmholtz resonators, and all manner of rigid fiberglass designs with and without air gaps and with and without limp mass membranes and reflective materials. For present purposes I am interested in quick and dirty bass absorption with no regard for aesthetics or other frequencies. Rolls of insulation stacked in the corner are said to be useful.


It seems, generally, that the effectiveness of fiberglass products increases with increasing density. Owens Corning Atticat isa loose fiberglass insulation that comes packaged in stackable plastic bags having dimensions of about 9"X 20"x 38" (about 4 cubic feet of volume). The weight is about 35lbs. Therefore, as packaged, it has a density of about 9 pcf. Rolls and other forms of fiberglass are far less dense. With OC 705 having a density of about 5 pcf, would we not expect Atticat to be a bit more effective at bass absorption than OC 705 per unit volume?


I don't find any mention of anyone trying to use this product as a bass absorber. I'm gonna try it, but before I do, perhaps someone out there can tell me that it doesn't work or why it won't work.


Thanks


----------



## Terry Montlick




> Quote:
> Originally Posted by *da crusher* /forum/post/15773802
> 
> 
> I've read for days concerning various DIY bass traps. Tubes, resonating panels, Helmholtz resonators, and all manner of rigid fiberglass designs with and without air gaps and with and without limp mass membranes and reflective materials. For present purposes I am interested in quick and dirty bass absorption with no regard for aesthetics or other frequencies. Rolls of insulation stacked in the corner are said to be useful.
> 
> 
> It seems, generally, that the effectiveness of fiberglass products increases with increasing density. Owens Corning Atticat isa loose fiberglass insulation that comes packaged in stackable plastic bags having dimensions of about 9"X 20"x 38" (about 4 cubic feet of volume). The weight is about 35lbs. Therefore, as packaged, it has a density of about 9 pcf. Rolls and other forms of fiberglass are far less dense. With OC 705 having a density of about 5 pcf, would we not expect Atticat to be a bit more effective at bass absorption than OC 705 per unit volume?



It should work, but how well compared to other fiberglass densities? I don't know.


You see, absorption is a function of material acoustic resistivity, thickness, and frequency. Acoustic resistivity increases with density. For fiberglass, it increases reasonably linearly from the data we have - up to 6 pcf. But I don't know above this point. I have no measured data. Mineral wool, on the other hand, shoots up pretty fast in resistivity (non-linearly) above roughly 5 pcf.


For any given frequency, there is an optimum region of porous absorber resistivity and thickness. If you are too far from this region, the absorption will not be maximum. This is known from a ton of empirical data analyzed back in the 80's.


Fortunately, the region is fairly broad. So if your are off some from the optimum, the absorber will still work very well.


That's about all the detail I can give before the subject gets pretty technical and ugly!










Regards,

Terry


----------



## da crusher

Terry, thank you. I shall try this and report my qualitative observations for whatever they might be worth.


Doug


----------



## DevonS

I did some searching for "Roxul", "Safe n Sound", "Roxul AND Soffits" and didn't quite find what I was looking for, so...


Using the following picture as a loose guide, I'm planning on building soffits along the sides of my theater. I was planning on simply building a skeleton, fill it with Safe n' Sound and basically wrapping it in GOM (or a suitable budget-friendly replacement).











My soffits will be 10 x 24-ish, so I plan on using 3 layers of 3" Safe n Sound. These will be down the sides of the theater. I plan on building some panels for first reflections and for around the screen, likely using the OC-703 if I can find it. I've compared values for Safe n Sound vs 3-inch 703 (plain) on this site. They seem very comparable... when you don't really know what you're reading










My main question is, the chunk between the insulation and light tray appears to be solid, and I've seen it as solid in nearly every soffit I've seen on here. Does it have to be solid or can that be just fabric too?


So... Is this a completely horrible idea? Keeping in mind I'm going from nothing to some SnS soffits and first reflection/screen-wall treatments.


----------



## want2beyounger

I am way back on page 5 of this thread and am planning a build of my own. Can someone help me along by explaining what RT60 refers to.


----------



## David James




> Quote:
> Originally Posted by *want2beyounger* /forum/post/15791770
> 
> 
> I am way back on page 5 of this thread and am planning a build of my own. Can someone help me along by explaining what RT60 refers to.



Google is your friend - first link in the list.


There are many others. Search string was: What is RT60.


----------



## want2beyounger




> Quote:
> Originally Posted by *David James* /forum/post/15791889
> 
> 
> Google is your friend - first link in the list.
> 
> 
> There are many others. Search string was: What is RT60.



I had may head so wrapped around this whole accustical thing, I forgot Google was my friend. Thanks


----------



## HT1

Hello,

I need some help with accoustic treatments. I know that waiting until the room is complete is probably not the best thing to do but since I'm a few days from carpet install I hope I'm not to late. I have a "multi purpose" room that is 19.5 X 46. Although it is one big open room it is basically cut in half with one side being a bar and the other side being a 120" screen with projector and 5.1 layout. The room has 2 entrances that do not have doors on them and one bulk head that runs the 46 feet length of the room. The area around the bar is tile, the area of the screen is to be carpet. All of the walls are painted drywall. I have a rough layout document that I can post if it helps. My goal is to be able to tame some of the echo and get the most out of my speakers and equipment using the layout and design of the current room. My question is where do I start?


----------



## SteveMo




> Quote:
> Originally Posted by *HT1* /forum/post/15806164
> 
> 
> Hello,
> 
> I need some help with accoustic treatments. I know that waiting until the room is complete is probably not the best thing to do but since I'm a few days from carpet install I hope I'm not to late. I have a "multi purpose" room that is 19.5 X 46. Although it is one big open room it is basically cut in half with one side being a bar and the other side being a 120" screen with projector and 5.1 layout. The room has 2 entrances that do not have doors on them and one bulk head that runs the 46 feet length of the room. The area around the bar is tile, the area of the screen is to be carpet. All of the walls are painted drywall. I have a rough layout document that I can post if it helps. My goal is to be able to tame some of the echo and get the most out of my speakers and equipment using the layout and design of the current room. My question is where do I start?



Start with trying to treat the front corners, then think about treating the first reflection points as well.


----------



## Ethan Winer




> Quote:
> Originally Posted by *HT1* /forum/post/15806164
> 
> 
> where do I start?



Steve gave you good advice. Much more here:

RealTraps Articles 
RealTraps Videos 


--Ethan


----------



## frostlich




> Quote:
> Originally Posted by *sound dropouts* /forum/post/15689860
> 
> 
> I am hoping to make a theater in the upstairs room of a house. The roof slants into the room, creating an odd shape. I am unsure how to acoustically treat the room. Attached is a rough drawing of what I hope the front will look like...where should I put acoustic treatemnts? Should I put them on the slanted parts as well?



I have nearly the exact setup as you are planning. My difference being I have smaller speakers which are wall mounted.


This setup not only presents some acoustical challenges, but some light reflection challenges as well. The screen will reflect a significant amount of light on the ceilings and walls. I just received some triple black velvet from syfabrics that does amazing things for light control. VERY impressive stuff.


So, not to hijack your request for info, but this may serve both our purposes:


I have not yet permanently mounted the velvet on the walls/ceilings. I understand that velvet is not optimum for acoustic treatments. However, I was thinking about using this as a covering fabric over some diy acoustic panels. As you can see in the the above picture, 2" thick panels would really push intruding in the viewing area(see sloped ceiling area).


Would 1 to 1.5 inch thick panels with velvet cover offer any noticable improvement worth the money? I believe the general opinion is some treatment is better than nothing. However, I haven't seen this shape of a room addressed very often, if at all. I'm not looking for a definative answer, just some added opinions before I justify spending the cash on the OC703.


----------



## bigeric

I got noticable improvement after putting bass traps in place and lining the front wall with 1" Linacoustic.


I've taken some measurements and am looking for some advice on the next steps.


After reading the recent discussion about not treating first reflection points, I'm not sure whether that is desirable or necessary.


Can you look at my measurements and give me some advice?


Thanks in advance,

Eric


Link to my thread:
http://www.avsforum.com/avs-vb/showt...1#post15820097


----------



## Dan Woodruff

Eric,

After doing it in my own room, I would put up an additional layer of linacoustic on your screen wall.


My wife didn't hear as much improvement as I did but she did notice.


----------



## SteveMo




> Quote:
> Originally Posted by *bigeric* /forum/post/15820138
> 
> 
> I got noticable improvement after putting bass traps in place and lining the front wall with 1" Linacoustic.
> 
> 
> I've taken some measurements and am looking for some advice on the next steps.
> 
> 
> After reading the recent discussion about not treating first reflection points, I'm not sure whether that is desirable or necessary.
> 
> 
> Can you look at my measurements and give me some advice?
> 
> 
> Thanks in advance,
> 
> Eric
> 
> 
> Link to my thread:
> http://www.avsforum.com/avs-vb/showt...1#post15820097



I would recommend a minimum use of 3", but my front wall has over 5". You will want to look at the waterfall tab or spectral decay in REW to observe the improvements in decay time. The different response should ring out more evenly if the treatment is helping the way we want it to. RT60 is not valid for small rooms, but it is interesting to try and figure out how the measurements are generated. Kudos for giving that a try. I think some of us are still stuck reading those articles from the late 90's.


Treating first reflection points is always desirable in home theater.


----------



## Terry Montlick




> Quote:
> Originally Posted by *SteveMo* /forum/post/15820457
> 
> 
> RT60 is not valid for small rooms, ...



It is at all but the lowest frequencies. Floyd Toole's statement is an oversimplification which gets people's attention at conferences. Presumably, it is meant to goose us acousticians into doing more research on residential-sized rooms instead of just concert halls and churches. But the truth is not black and white.


I and others measure very nice, smooth reverberation decays at 500 Hz and above in small rooms. For some rooms, the 250 Hz octave band is not as good, and in general, the 125 Hz octave band is dodgy.


Linearity of scale is a fundamental principle of acoustics. It's what allows us to build scale models of rooms and obtain meaningful acoustical measurements*. All you do is scale the frequencies accordingly. A reverberant sound field at 400 Hz in a 100 foot space translates to an equally reverberant sound field in a 20 foot space at 2 kHz.


Regards,

Terry


* There is an air absorption effect at high frequencies which does not scale. But this is easily adjusted for.


----------



## SteveMo

I beleave that we are not all in agreement with that in other parts of the world, but please don't quote me on that.


----------



## rutlian

After following this thread and gathered very good informations from the experts, I added sound absorption in our HT and my next project will be adding bass trap for the front corners, I am glad I did this and very happy with improvement, Before, my wife hate to watch with me because I have to crank up the volume but now she loves it I told her I've been using same level of volume eversince I put this up and she can't believed the improvement. The only stopping me for the bass trap in the corner is if I needed to build a false wall, If I can find a way of putting a bass trap in the corner without building a false wall to hide it that would be great. My Room is just 13x22x7.5


I am open to suggestions you guys can give base from what I have now. Thanks












































After watching a few movies WOW what really an improvement, before I could not differentiate the sounds coming from my main L/R fronts

now it is very clear and it sounds is more solid and much much better.


----------



## Russell Burrows




> Quote:
> Originally Posted by *JBS* /forum/post/2176287
> 
> 
> OK, this seems straightforward from searching AVS and studying theater wall treatment...
> 
> 
> FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.
> 
> CEILING: No acoustical treatment - none, nada.
> 
> FLOOR: Thick, plush carpet is fine.
> 
> 
> But here's where it gets confusing, and I need help...
> 
> 
> SIDEWALLS
> 
> A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.
> 
> --or--
> 
> B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.
> 
> 
> These 2 theories seem to contradict each other. So which is it?
> 
> 
> 
> BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:
> 
> 
> Owens Corning Select Sound Black Acoustic Board
> 
> Owens Corning Fiberglas 703 Series duct insulation.
> 
> Johns Manville Insul-Shield
> 
> Johns Manville Linacoustic Permacoate rolls.
> 
> Certainteed Certpro Acoustaboard Black
> 
> Knauf Duct board EI-475
> 
> Knauf Duct liner EM
> 
> 
> ...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.






For 18 hertz to 100 hertz standing wave controll you want sonotubes cut to X length depending on offending frequency with a crappy five dollar subwoofer at one end that absorbs standing waves via woofer movement.


NOTE.

The crappy five dollar subwoofer does NOT have any wires going to it.


Its a perfect Hemholtz resonator thats way above any competing products for base absorption in the 18 hertz to 100 hertz ranges.


----------



## R Harkness

HELP: My workers are just about to finish framing a bulkhead we've applied to my ceiling. I'm wondering if there might be a decent opportunity here to apply some acoustic absorption in the portion of the bulk head running along the top of the screen wall. (I'm hoping to tame a bit of bass bloat, ideally, but otherwise I would hope this would do _something_ beneficial).


The bulkhead portion above the screen is 12 foot 9 inches long, 24 inches wide and 6 inches thick from the ceiling. I wonder if we can make a frame that shape and, since I'm going to cover the entire bulkhead with fabric, just fit some sort of acoustic material in the portion over the screen.


Any suggestions? Here are to depictions of my screen wall, looking up so you can see the bulkhead that is being built from the ceiling. In the second image I've indicated a sort of frame idea (to be covered in fabric) in the bulkhead in front of the screen:

 
 


With the bulkhead trap indicated above the screen:


----------



## SteveMo




> Quote:
> Originally Posted by *R Harkness* /forum/post/15827987
> 
> 
> HELP: My workers are just about to finish framing a bulkhead we've applied to my ceiling. I'm wondering if there might be a decent opportunity here to apply some acoustic absorption in the portion of the bulk head running along the top of the screen wall. (I'm hoping to tame a bit of bass bloat, ideally, but otherwise I would hope this would do _something_ beneficial).
> 
> 
> The bulkhead portion above the screen is 12 foot 9 inches long, 24 inches wide and 6 inches thick from the ceiling. I wonder if we can make a frame that shape and, since I'm going to cover the entire bulkhead with fabric, just fit some sort of acoustic material in the portion over the screen.
> 
> 
> Any suggestions? Here are to depictions of my screen wall, looking up so you can see the bulkhead that is being built from the ceiling. In the second image I've indicated a sort of frame idea (to be covered in fabric) in the bulkhead in front of the screen:
> 
> 
> 
> 
> 
> With the bulkhead trap indicated above the screen:



Since it is an area you are concerned about possible bass build up, that area should be very well constucted espicially for the subwoofer. I might check unless you already did. What to do with the area above the screen? I personally would attempt at placing some regular insulation up there, then something rigid under that so as to support the absorption above and keep it from being lumpy. After some sturdy support bracing under the rigid absorption (not overdone) you could place the fabric over the area however you needed for the hidden treatment.


----------



## unclepauly

Sorry to be so off topic but I've just moved into a house that has an awful acoustic environment for loud kids that are easily exciteable. I'd like to absorb some of this mess before it reaches my poor brain. My question is if there is anything I can just make home made that has a 100% or near 100% absorption that also won't look like a complete mess?


I realize I could just tell them to shut up.


Thanks. Please.


----------



## ScruffyHT




> Quote:
> Originally Posted by *unclepauly* /forum/post/15839735
> 
> 
> Sorry to be so off topic but I've just moved into a house that has an awful acoustic environment for loud kids that are easily exciteable. I'd like to absorb some of this mess before it reaches my poor brain. My question is if there is anything I can just make home made that has a 100% or near 100% absorption that also won't look like a complete mess?
> 
> 
> I realize I could just tell them to shut up.
> 
> 
> Thanks. Please.



Are you trying to stop the sound from echoing when they are yelling in the same room as you or ...


are you trying to create a room for them that they can yell away in and you cant hear them in the rest of the house ?


If it is the first then there are lots of examples of DIY acoustic panels in this forum ... just do a search


If it is the latter then visit www.soundproofingcompany.com and read the articles in the library


----------



## unclepauly

A little of both actually. This house echos like crazy and I'd like to treat all the hotspots. I'll look into that link and do a search thanks.


----------



## CJO

earplugs


CJ


----------



## Terry Montlick




> Quote:
> Originally Posted by *SteveMo* /forum/post/15859407
> 
> 
> What would one say my RT60 is? There is alot of trapping in the room.



Perhaps too much.










Looks like this was measured with Room EQ Wizard, which actually does a good job in calculating RT60. The reverberation times should ideally be the same over frequency, at least down to 200 Hz. The EBU recommends to within 0.05 seconds. When they are not, and there is more reverb at high frequencies, the subjective impression can be of a "too live" high end, or a "too dead" low end.


Regards,

Terry


----------



## R Harkness

*Terry Montlick,*


Can you give any comment on my question about possibly employing acoustic absorption above the screen (as in the room sketches I supplied above)?


I'm trying to figure out if it will be worth the hassle (any benefit), and I am at that critical part of construction so I have to make the decision.


Thanks.


----------



## Jerry Parker

I have a large living room, the dimensions are approximately 20 feet by 25 feet. The ceilings are vaulted, and approximately 15 feet tall at the top. My dining room is directly attached to the back of the room and open, so it extends another 12 feet, and is around 15 feet wide. All of the flooring is porcelain tile. The walls are covered with wood paneling that has been painted over. The ceiling is sheetrock.


As you can see, all of these factors contribute to a very live, reverberant space. I just purchased this house recently, and before I moved any furniture in, it was pretty much an echo chamber in my living room. Now, with furniture and a rug, it is slightly better, but still way too reverberant for serious music/movies listening.


I was thinking about purchasing some acoustic panels, these actually: http://www.atsacoustics.com/item--AT...8x4--1008.html 


I was going to purchase 6 of them, but is that even enough to make a difference in such a large room? Their 'calculator' says I need approximately 75 of them, but I figure that is for a veritable anechoic chamber.


Will 6 of these panels make an easy to hear difference, or am I better off spending my money on something else?


----------



## SteveMo




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15859567
> 
> 
> Perhaps too much.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Looks like this was measured with Room EQ Wizard, which actually does a good job in calculating RT60. The reverberation times should ideally be the same over frequency, at least down to 200 Hz. The EBU recommends to within 0.05 seconds. When they are not, and there is more reverb at high frequencies, the subjective impression can be of a "too live" high end, or a "too dead" low end.
> 
> 
> Regards,
> 
> Terry



You answered my post before I could delete it and it wasn't there very long.







I had my speaker ports plugged on accident and I'm not sure how this would have effected the results. I will try again this morning. My mic clips because of the reflections off the back of my couch. I will try and see if I can get one without it clipping. These are without the front wall treated for which I ordered some OC 705 2" to cover it with.


----------



## SteveMo

Here are some mesurements of my progress. I calibrated levels with my THX optimizer, then I turned down the level on my pre/pro to an 80dB target in REW. There was a thin blanket behind the mic, and no clipping this time. At an 85dB target REW said I had .01 headroom. The subwoofer level on my Outlaw was: subwoofer -3 and the other speakers were -3 to -2. It's a bypass multichannel input with the internal 80Hz crossover set to on. Measurements are 0Hz - 2000Hz 1 sweep at 256K. The levels matched so I used the calibration of the soundcard using my external source. The Helmholtz Resonator in the back of my room was converted to a broadband bass trap and the corners have insulation. The back of the rooms ceiling has no insulation exluding the insulation in the tiles. The traps in the back are 1/4 full each from the corners.


Left channel decay


(Treatments in this area are...GIK Pillar Trap, 3 GIK 244's, a 2" panel, GIK Monster Trap, lower and upper walls corner trapping with light or thick insulation, upper ceiling 2" pink inside tiles and Quiet Batt above that.2" panels cover the front wall stage.)











Right channel decay.


(Treatments in this area are...GIK Pillar Trap, 3 GIK 244's, a 2" panel, GIK Monster Trap, lower and upper walls corner trapping with light or thick insulation, upper ceiling 2" pink inside tiles and Quiet Batt above that. 2" panels cover the front wall stage.)


Right channel decay










Center channel decay


The speaker is sitting on a subwoofer with concrete tiles under it between the left and right channels. All speakers including the center channel are the same model at this time. There is no absorbtion on the front wall behind where the screen will be right now.











Right surround decay


(treamtents in this area are a large broadband bass trap under it, small corner trapping with Rockwool 60 above that next to the speaker, and the ceiling tiles. There is concrete laying under the speaker and on the large broadband bass trap that it sits on. Subwoofer nearby is decoupled from the stage now with a hole inside the stage sitting on concrete tiles surrounded by insulation. Walls behind and to the side of the speaker are bare.











Left surround decay


(treamtents in this area are a large broadband bass trap under it, small corner trapping with Rockwool 60 above that next to the speaker, and the ceiling tiles. There is concrete laying under the speaker and on the large broadband bass trap that it sits on. Subwoofer nearby is decoupled from the stage now with a hole inside the stage sitting on concrete tiles surrounded by insulation. The wall behind and to the side of the speaker are bare. There is a hollow core steel door with 4" traps on it nearby.











RT60 of all speakers. I am aware this isn't how to measure RT60 but it's interesting to look at in this case. My left surround measures a higher RT60, the worst looking response I have of all speakers.


Red = Left

Blue = Center

Green = Right


(I always use those colors now)


Surround left = orange

Surround right = purple


(these look like good colors to use???)











Any interpretations of these results? These RT60 measurements are _sort-of_ accrurate?










Edit: There is also corner trapping with Rockwool 60 behind the Pillar traps.


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/15860971
> 
> *Terry Montlick,*
> 
> 
> Can you give any comment on my question about possibly employing acoustic absorption above the screen (as in the room sketches I supplied above)?
> 
> 
> I'm trying to figure out if it will be worth the hassle (any benefit), and I am at that critical part of construction so I have to make the decision.
> 
> 
> Thanks.



In general, absorption at or near the front is good. In general, bass absorption, as afforded by a thick absorber placed in a corner, is good (though SteveMo's recently posted RT60 times from REW appear to show too much LF absorption).


As to whether it is good for your specific room with a reasonable degree of certainty, I don't know. There is a ton of additional detail required, and even then, it can take me hours to come up with an evaluation/diagnosis/treatment plan. Sorry that there is no simple answer.










Regards,

Terry


----------



## SteveMo

I can say that it sounds alot better than 1/2" DW/insulation inside 2X4 stud wall/concrete and it probobly sounds better than DW/steel ceiling. I'm also glad I didn't keep the concrete & steel room a 20X20 square.


----------



## R Harkness




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15869254
> 
> 
> In general, absorption at or near the front is good. In general, bass absorption, as afforded by a thick absorber placed in a corner, is good (though SteveMo's recently posted RT60 times from REW appear to show too much LF absorption).
> 
> 
> As to whether it is good for your specific room with a reasonable degree of certainty, I don't know. There is a ton of additional detail required, and even then, it can take me hours to come up with an evaluation/diagnosis/treatment plan. Sorry that there is no simple answer.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards,
> 
> Terry



Thanks Terry. Just so I am clear, you say in general a thick absorber placed in the corner is good for bass absorbtion.


Does the panel location shown in my pictures counts as "being in the corner?" It's a panel that touches the top corner of the screen wall, but I don't know if that counts as being in a corner in terms of the proper place to

get bass absorbtion benefits. (Or whether you need a trap that somehow actually spans the two sides of a corner, like a corner trap, to do the job).


Thanks,


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/15870312
> 
> 
> Does the panel location shown in my pictures counts as "being in the corner?"



To be technically correct, I should have said "edges" instead of "corners." A shoe box shaped room has 12 edges. They are all good places to absorb bass. Each edge is a high pressure zone for all the room modes in 2 out of 3 dimensions. Only the "real" (3-way) corners, of which there are 8, cover modes in all three dimensions. But it is hard to place really deep absorbers in those corners without cutting off a lot of space in the room.


----------



## R Harkness

Got it, thanks Terry.


My idea is to cover the entire dropped ceiling in a fabric that would be both light absorptive (to cut reflections down for the projected image) and that is also a suitable covering for the portion of the ceiling containing the bass trap. Do I have to limit my choice of fabric somehow? I.e. does the fabric have to have some distinct level of acoustic transparency (like speaker grill) or will most fabrics allow the sound through to let the bass trap material absorb the sound?


Anyone?


Thanks.


----------



## BWG707

Hello, I'm very new to acoustical treatments, I have been reading up on it when I've had the time but I need advice for my small, 10'x12' room. What I need to know is this: on the 12' side walls I have a 5'x6' window on one side and on the other side I have a 7'x6'6" closet with folding doors (made out of the same material that the interior doors are made out of, hollow core). If I use 2" O.C. 703 acoustic panels (4-18"x4') on the folding closet doors and nothing on the other wall with the window will it hurt my SQ, possibly make it uneven? The window is dual paned with miniblinds and lightly insulated curtains. I am also thinking about acoustic panels on the back wall and maybe a couple smaller panels behind my front speakers. Bass traps will probably come a little later. I appreciate any replys at all, I'm planning on starting my DIY panels very soon. Thanks


----------



## SteveMo




> Quote:
> Originally Posted by *BWG707* /forum/post/15877999
> 
> 
> Hello, I'm very new to acoustical treatments, I have been reading up on it when I've had the time but I need advice for my small, 10'x12' room. What I need to know is this: on the 12' side walls I have a 5'x6' window on one side and on the other side I have a 7'x6'6" closet with folding doors (made out of the same material that the interior doors are made out of, hollow core). If I use 2" O.C. 703 acoustic panels (4-18"x4') on the folding closet doors and nothing on the other wall with the window will it hurt my SQ, possibly make it uneven?



It might not be as noticable if there is lots of absorption inside the closet. Be cautious of things in there that are in contact with the wall that is rigid. If you add panels there will be a damping effect but the stiffness of any shelving in there could add a bump to the absorption based on what frequencies are conducted through the panel. It's like hanging a panel with a larger frame versus hanging one with a smaller frame. Consider the mass of the panel and things nearby because as panels vary in there framing, this alters the absorbtion coefficients of very low frequencies and it can cause decay to last longer or shorter to that direction which can become distracting if there are sounds that are low in frequency panning left to right, or only all left, or only all right. You can experement by listening to the tones of your wall with the closet versus next to the other wall. You may find thicker panels on the door to give it a greater mass works best, but thats only a suggestion and to be taken with a grain of salt. Filling the closet with as much of any kind of damping material will help. Try leaving an air space between the wall in the HT, and the damping material.



> Quote:
> The window is dual paned with miniblinds and lightly insulated curtains. I am also thinking about acoustic panels on the back wall and maybe a couple smaller panels behind my front speakers. Bass traps will probably come a little later. I appreciate any replys at all, I'm planning on starting my DIY panels very soon. Thanks



You might place some furniture near the window if there is not already. It may not be a problem. You could try placing a panel on a stand in front of it. Is there room for some panels to straddle the front corners? Might try some thicker panels straddling the corners. Then you can also try them on the back wall and behind the speakers. For smaller rooms it is usually best to avoid thin panels if possible.


----------



## BWG707




> Quote:
> Originally Posted by *SteveMo* /forum/post/15878219
> 
> 
> It might not be as noticable if there is lots of absorption inside the closet. Be cautious of things in there that are in contact with the wall that is rigid. If you add panels there will be a damping effect but the stiffness of any shelving in there could add a bump to the absorption based on what frequencies are conducted through the panel. It's like hanging a panel with a larger frame versus hanging one with a smaller frame. Consider the mass of the panel and things nearby because as panels vary in there framing, this alters the absorbtion coefficients of very low frequencies and it can cause decay to last longer or shorter to that direction which can become distracting if there are sounds that are low in frequency panning left to right, or only all left, or only all right. You can experement by listening to the tones of your wall with the closet versus next to the other wall. You may find thicker panels on the door to give it a greater mass works best, but thats only a suggestion and to be taken with a grain of salt. Filling the closet with as much of any kind of damping material will help. Try leaving an air space between the wall in the HT, and the damping material.
> 
> 
> 
> 
> You might place some furniture near the window if there is not already. It may not be a problem. You could try placing a panel on a stand in front of it. Is there room for some panels to straddle the front corners? Might try some thicker panels straddling the corners. Then you can also try them on the back wall and behind the speakers. For smaller rooms it is usually best to avoid thin panels if possible.



First of all thank you for the quick reply. My closet is filled with lots of clothes hanging on a pole. Also what thickness of CO 703 would you recommend and how much of an air gap should I leave? You are talking about a air gap between the wall and the acoustic panel correct? What treatments in a small room (10'x12') would give me the most improvement? Would it be panels or bass traps? Which area of the room would benefit most from acoustic treatment? I know it's kinda hard to answer these Qs without seeing the room but just general answers would help me. Thanks again. Edit: Is it beneficial to put panels behind speakers that are ported, that includes subs that are rear ported?


----------



## SteveMo




> Quote:
> Originally Posted by *BWG707* /forum/post/15878378
> 
> 
> First of all thank you for the quick reply. My closet is filled with lots of clothes hanging on a pole. Also what thickness of CO 703 would you recommend and how much of an air gap should I leave? You are talking about a air gap between the wall and the acoustic panel correct? What treatments in a small room (10'x12') would give me the most improvement? Would it be panels or bass traps? Which area of the room would benefit most from acoustic treatment? I know it's kinda hard to answer these Qs without seeing the room but just general answers would help me. Thanks again. Edit: Is it beneficial to put panels behind speakers that are ported, that includes subs that are rear ported?



Clothes, yes those work very well.


A thick panel is considered a bass trap, because it gets down into the low frequencies where bass is a problem. A panel that is 4" - 7" or more is considered a bass trap, and those can be good for straddling the corners. You could also use a pair of panels in the corner to increase the thickness. This is good if you don't want to have to install something permanantly in the corner or build a superchunk to only find it is too small or too large. You can experement with one by placing insulation or other damping materials behind it to see what return benifits you have, and this can give an idea what to plan for should you need to have more effective bass trapping in the corners later on.


You want to cover the room in an even amount of absorption spread around the room, and the thicker panels will get into the lower frequencies were most problems will be at. I would try experementing with a pair of thick panels around the room and see where you get the most benifit. The comb filtering can smear the acoustical imaging, and this problem is in the lower fequencies in a small room because the acoustical interferance is greater as speakers are closer to the walls, have more sound reinforcement that is not sound from the speaker, but instead sound reflecting off the wall to the listening area. When you add a bass trap to the wall at your first reflection points the sound is absorbed and what you hear is the off-axis response mixed into the movie that is from the speaker, not effected by the wall. You will probobly want to start with the front of the room, because this is where most sound is being reflected towards what we hear causing the distruction of the soundfield.


I have found that when you put absorption behind a ported speaker there can be a benifit, but this is difficult to predict. It might be treating a problem where in fact the problem is sound of the wall going over into a corner for example. If your not sitting directly in the path of the sounds that are coming off the wall it might not be as noticable a difference with the panel behind the sub. You can easily tune the difference by moving the subwoofer away from the absorption, but it might mean moving it far from the panel. A general rule is to keep the subwoofer X2 the distance from the wall as the diamater of the port on the subwoofer. You can also try experementing as I do by placing you ear right up next to the opposite wall and see if the sound is tight, or muffled with a scene that contains lots of bass bellow the tuning frequency of the subwoofer.


----------



## SteveMo

Here is one of my new bass traps in the rear of the room being built. It's a plywood box that has openings and fabric on the front with trim around it. There is R30 and R19 inside.


----------



## BWG707

In a small room, 10'x12'x8', should I use diffusers or absorbers on the rear wall, behind the listening position? Thanks for any replys.


Nevermind, I found the info, thanks anyway.


----------



## SteveMo

Here are some new results. looks like there are now more peaks around the 60Hz - 167Hz area now instead of the ones around 340Hz - 572Hz since moving the speakers some to make them match better.
Took the kraft paper off insulation in the stage & uncompressed it some
Moved more 2" panels over the stage
Covered the front wall with OC 705 2"
Moved the Pillar Traps away from the corners some & removed insulation under them
Removed alot of concrete from the room awaiting to be filled
Filled rear traps with insulation
Removed plywood, blankets clothes, from the rear ceiling & replaced with insulation
Placed insulation in areas to maintain symmetry
Moved speakers away from the listening position inches
Didn't equalize bellow 50Hz











Left speaker + subwoofers











Right speaker + subwoofers











I tried my best to match the speakers but they have been taken apart and repaired, so that may be impossible. I added one layer of the cloth material from extra speakers behind the lower second drivers in each speaker since they did not have any if that makes any difference to these results. The speakers themselves begin to vibrate and resonate some around 250Hz, but they always did. I thought it might help that. One of them may not have the extra material inside of it but I would have to check to be certain. Guessing I would say the right does not. The RS Meter was pointing up for the measurements.


edit: The right speaker had the extra peice of absorption behind the speaker inside I added recently. I don't think that I will need that anymore so I removed it.


----------



## Terry Montlick

Hi Steve,


Trying to read a series of decay curves is almost as hard as reading the tea leaves in a waterfall diagram. Very pretty, but what do they mean?










Info that must accompany such diagrams in order to have hope of making any sense at all out of them are the analysis window size in ms, plus the time interval between "slices," or the overall time duration and the number of slices which divide up this time.


Regards,

Terry


----------



## Terry Montlick

Also, better to show RT60 graphs on a vertical scale with at least 0.1 second grid markings, like you did earlier. John Mulcahy's REW calculation for RT60 is one of the few out there that I would trust.


----------



## SteveMo




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15899062
> 
> 
> Hi Steve,
> 
> 
> Trying to read a series of decay curves is almost as hard as reading the tea leaves in a waterfall diagram. Very pretty, but what do they mean?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Info that must accompany such diagrams in order to have hope of making any sense at all out of them are the analysis window size in ms, plus the time interval between "slices," or the overall time duration and the number of slices which divide up this time.
> 
> 
> Regards,
> 
> Terry



To empty my ceiling, rear traps, stage trapping, partition wall, are all very difficult to show as an example, but I can remove all of the others ones more easy. The other ones I measure so they are exact on each side to 1/2". I will remove those later today so we can see the difference I am trying to show. Wouldn't it be easier to simply read the thousands of post about it?







The window is the default settings in REW but you can see the vertical and horizontal scale on the graphs.


----------



## SteveMo

Here you are. These show some of the changes in a condensed fashion. Sorry if you not are as impressed with this as I am. I choose each treatment the best I could for an even coverage of absorption. I usually listen to music around 92dB and moves from -14dB reference and more commonly -4dB to 0dB reference.


Room treatments where they are.










Removed 2" panels from the front of the stage.










Removed a pair of 2" ATS panels and 6 GIK 244's from first reflection points.










Removed the pair of GIK Pillar Traps. Ouch!










Removed the pair of GIK Moster Traps.










Removed the 6 panels of OC 705 from the front wall.










Left in the room in that graph is the ceiling absorption, rear traps, stage trapping, corner trapping, panels on the door, and the riser if you wanted to count that.


----------



## rutlian

newbie questions to all experts:


with all these graphic testing, data sheets or anything you like it to be called, how and when a hometheater owner can get satisfied, do I need to do these testing too or just listen with my sounds and if I like the way it sounds in my dedicated hometheater do I stop and enjoy movies or should I continue on calibrating my sounds but when should I stop if I go that route. Currently I have sound abpsortion all 12 24x48x2 2 24x24x2 scattered in my hometheater, should I go with more treatment for me right now I am satisfied and very happy with the result, but should I do testing? or stop right here since I am happy already. Very confused with all these graphics










Thanks


----------



## SteveMo




> Quote:
> Originally Posted by *rutlian* /forum/post/15913195
> 
> 
> newbie questions to all experts:
> 
> 
> with all these graphic testing, data sheets or anything you like it to be called, how and when a hometheater owner can get satisfied, do I need to do these testing too or just listen with my sounds and if I like the way it sounds in my dedicated hometheater do I stop and enjoy movies or should I continue on calibrating my sounds but when should I stop if I go that route. Currently I have sound abpsortion all 12 24x48x2 2 24x24x2 scattered in my hometheater, should I go with more treatment for me right now I am satisfied and very happy with the result, but should I do testing? or stop right here since I am happy already. Very confused with all these graphics
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks



Do you find yourself having to adjust the volume level alot from movie to movie, adjusting the center channel level or perhaps trying to move it to one side? Do sounds from one speaker to the next sound like a smooth transition?


Here is a recording I made awhile back of before making changes to the room and adding treatments and as it is now. It's easy to hear the difference.


Previous recording

http://www.4shared.com/file/76595402...tey_dance.html 


Recording after new treatments with some other changes in the room.

http://www.4shared.com/file/89479731...dance_new.html


----------



## rutlian

Thanks for the info steve, I will listen to it tonight when I go home, I appreciate it I am sure this will help me understand a lot.


Thanks,


----------



## MarkMac




> Quote:
> Originally Posted by *SteveMo* /forum/post/15913686
> 
> 
> Here is a recording I made awhile back of before making changes to the room and adding treatments and as it is now. It's easy to hear the difference.
> 
> 
> Previous recording
> 
> http://www.4shared.com/file/76595402...tey_dance.html
> 
> 
> Recording after new treatments with some other changes in the room.
> 
> http://www.4shared.com/file/89479731...dance_new.html



SteveMo-

No dice on those links. Any chance you could re-post? I'd like to try them out.


----------



## SteveMo




> Quote:
> Originally Posted by *MarkMac* /forum/post/15917384
> 
> 
> SteveMo-
> 
> No dice on those links. Any chance you could re-post? I'd like to try them out.



Try using the sites download page.


Previous

http://www.4shared.com/file/76595402...tey_dance.html 


Recent

http://www.4shared.com/account/file/...dance_new.html 


You will have to excuse the quality of the RS Meter mic in these. The meter was set to 100 and the playback level was 0dB. Right and left channel levels were the same values which gave results like in the graphs above. The previous one needed some level matching, but I have not checked a calibration disc yet.


----------



## rutlian

Listened to both and definitely could tell the diff from the two, I am glad I put some treatment in my HT. Thanks for sharing steve.




> Quote:
> Originally Posted by *SteveMo* /forum/post/15913686
> 
> 
> Do you find yourself having to adjust the volume level alot from movie to movie, adjusting the center channel level or perhaps trying to move it to one side? Do sounds from one speaker to the next sound like a smooth transition?
> 
> 
> Here is a recording I made awhile back of before making changes to the room and adding treatments and as it is now. It's easy to hear the difference.
> 
> 
> Previous recording
> 
> http://www.4shared.com/file/76595402...tey_dance.html
> 
> 
> Recording after new treatments with some other changes in the room.
> 
> http://www.4shared.com/file/89479731...dance_new.html


----------



## dc_pilgrim

I am planning to make a false soffit along the lines of this design:











I am wondering if it is better to


- fill it to the brim with Acoustic cotton or OC 703, or


- do superchunk wedges of OC 703?


Let me guess, it depends on the room and the problem frequencies?


Here are pics of each basic design, since I like pictures.


Cotton-ie:


> Quote:
> Originally Posted by *SandmanX* /forum/post/6635612
> 
> 
> Here is the Side Soffit (without Light Tray). Notice the bass absorbtion in there as well.



Chunky:


----------



## MarkMac




> Quote:
> Originally Posted by *SteveMo* /forum/post/15918943
> 
> 
> Try using the sites download page.
> 
> 
> Previous
> 
> http://www.4shared.com/file/76595402...tey_dance.html
> 
> 
> Recent
> 
> http://www.4shared.com/account/file/...dance_new.html
> 
> 
> You will have to excuse the quality of the RS Meter mic in these. The meter was set to 100 and the playback level was 0dB. Right and left channel levels were the same values which gave results like in the graphs above. The previous one needed some level matching, but I have not checked a calibration disc yet.



Thanks for posting that. There's a significant difference in voice intelligibility. Funny, I didn't think the "old" one was too bad until I listened to the new. That's probably what about 95% of home theater owners would say after they've discovered room treatments (if they ever do).


----------



## pepar




> Quote:
> Originally Posted by *dc_pilgrim* /forum/post/15931517
> 
> 
> I am planning to make a false soffit along the lines of this design:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I am wondering if it is better to
> 
> 
> - fill it to the brim with Acoustic cotton or OC 703, or
> 
> 
> - do superchunk wedges of OC 703?
> 
> 
> Let me guess, it depends on the room and the problem frequencies?
> 
> 
> Here are pics of each basic design, since I like pictures.
> 
> 
> Cotton-ie:
> 
> 
> 
> Chunky:



I think that the SSC profile is triangular because adding the "second" triangle to make it square wouldn't add that much to the performance. And I think the same would apply to the cotton. As for the effectiveness of the two materials, I *think* the 703 is better, but you should consult the absorption chart at http://www.bobgolds.com/AbsorptionCoefficients.htm .


----------



## Triaxtremec

I currently have nearly finished my theater room, now its just a matter of where to place my acoustic panels. I have made six 2ft x 4ft panels and want to know the best placement based on my room design. I have read that you want to absorb any reflective sound between the front of the room and the listener yet leave the back of the room more reflective to liven up the rear channels, is this correct. Any help would be appreciated.


----------



## rigman

Hi guys


silly question but..


If you dont have an acoustically transparent screen (Carada BW 2.35) then is there any benefit in placing acoustic material directly behind the screen?


Will it still absorb some sound reflections?


My speakers will be below the screen.


thanks for any advice

Darren


----------



## Dennis Erskine

Triax ...

You're placing a full range speaker next to a wall boundary and effectively in a corner. You'll need very significant treatment in those areas.


----------



## dc_pilgrim




> Quote:
> Originally Posted by *pepar* /forum/post/15935247
> 
> 
> I think that the SSC profile is triangular because adding the "second" triangle to make it square wouldn't add that much to the performance. And I think the same would apply to the cotton. As for the effectiveness of the two materials, I *think* the 703 is better, but you should consult the absorption chart at http://www.bobgolds.com/AbsorptionCoefficients.htm .



So that is why they are triangles? Its basically bang for buck? So by doing triangles you can cover double the space for the material provided?


I didn't know that. I'd like to see more on the theory around the how's and why's of the chunks. I picked up some rigid fiberglass second hand, I certainly would prefer to stretch out the stock on hand. . .


----------



## pepar




> Quote:
> Originally Posted by *Triaxtremec* /forum/post/15940207
> 
> 
> I currently have nearly finished my theater room, now its just a matter of where to place my acoustic panels. I have made six 2ft x 4ft panels and want to know the best placement based on my room design. I have read that you want to absorb any reflective sound between the front of the room and the listener yet leave the back of the room more reflective to liven up the rear channels, is this correct. Any help would be appreciated.



If it were my room:











4" behind the front speakers, 2" everywhere else. What is the floorcovering?


Also, I would pull the front speakers away from the front wall.


----------



## pepar




> Quote:
> Originally Posted by *dc_pilgrim* /forum/post/15941657
> 
> 
> So that is why they are triangles? Its basically bang for buck? So by doing triangles you can cover double the space for the material provided?



Yes.



> Quote:
> I didn't know that. I'd like to see more on the theory around the how's and why's of the chunks. I picked up some rigid fiberglass second hand, I certainly would prefer to stretch out the stock on hand. . .



Here is the specific section on the Studiotips forum for the SuperChunk trap . I suggest you read it and then pull back to and read the other sections in the Acoustics FAQ. If you still have questions, find the appropriate thread and post your question(s).


----------



## Triaxtremec

Pepar, thanks for the advice. It's a crude diagram, I don't know how to use anything other than Microsoft paint but the speakers are about 4-6in's from the wall and the center is elevated on a stand 21in's tall, also 4-6in's from the wall. The floors are all carpeted and on the back wall, behind the couch, is a window which is covered with a thick curtain.


----------



## pepar




> Quote:
> Originally Posted by *Triaxtremec* /forum/post/15941824
> 
> 
> Pepar, thanks for the advice. It's a crude diagram, I don't know how to use anything other than Microsoft paint but the speakers are about 4-6in's from the wall and the center is elevated on a stand 21in's tall, also 4-6in's from the wall. The floors are all carpeted and on the back wall, behind the couch, is a window which is covered with a thick curtain.



If you have the space, I would suggest moving LCR further from the front wall. A thick curtain is not a broadband absorber and that is very important when the listeners are so close to the rear wall. Moving the sectional farther from the rear wall would help if you cannot use an absorber in the window cavity. The ottoman many need to go as it looks like it would block the entryway if the sectional was moved "north."


Just my $.02.


----------



## David James




> Quote:
> Originally Posted by *pepar* /forum/post/15941771
> 
> 
> Yes.
> 
> 
> 
> Here is the specific section on the Studiotips forum for the SuperChunk trap . I suggest you read it and then pull back to and read the other sections in the Acoustics FAQ. If you still have questions, find the appropriate thread and post your question(s).



I've gone down the SuperChunk path and have a question I haven't seen discussed. Rather then simply putting the wedges into the corner, would there be a negative impact to putting the SuperChunk wedges into an enclosure. Here is an example I built for a small half wall in my theater. Naturally, it's normally pushed into the corner and the front will eventually be covered with cloth.


----------



## Dennis Erskine




> Quote:
> 4" behind the front speakers, 2" everywhere else.



You're going to need at least 4" (depending upon 4" of what) on those walls to the sides of the speakers to about 6' (if not more) from the corner.


----------



## Triaxtremec

I've moved the speakers further away from the wall as well as moved the couch further towards the screen about another 1.5ft(not shown in diagram). That's about all I can go without the room looking odd. Here is where I was thinking of placing my panels, I will eventually place some smaller ones behind the front speakers but my panels are just to large for that.

How's this look? (panels are highlighted in red)


----------



## will1383

I would make those rear corners complete bass traps.


----------



## pepar




> Quote:
> Originally Posted by *David James* /forum/post/15942032
> 
> 
> Rather then simply putting the wedges into the corner, would there be a negative impact to putting the SuperChunk wedges into an enclosure. Here is an example I built for a small half wall in my theater. Naturally, it's normally pushed into the corner and the front will eventually be covered with cloth.



Looks good.


----------



## pepar




> Quote:
> Originally Posted by *Triaxtremec* /forum/post/15944797
> 
> 
> I've moved the speakers further away from the wall as well as moved the couch further towards the screen about another 1.5ft(not shown in diagram). That's about all I can go without the room looking odd. Here is where I was thinking of placing my panels, I will eventually place some smaller ones behind the front speakers but my panels are just to large for that.
> 
> How's this look? (panels are highlighted in red)



"Small" panels on the front wall won't really do it.


----------



## Triaxtremec

Well I don't have the ability to make a false wall or insulate the hell out of the area. But for what I have will the red area's work?


----------



## rigman




> Quote:
> Originally Posted by *rigman* /forum/post/15941068
> 
> 
> Hi guys
> 
> 
> silly question but..
> 
> 
> If you dont have an acoustically transparent screen (Carada BW 2.35) then is there any benefit in placing acoustic material directly behind the screen?
> 
> 
> Will it still absorb some sound reflections?
> 
> 
> My speakers will be below the screen.
> 
> 
> thanks for any advice
> 
> Darren



Oh what the heck I will do it anyway. Otherwise it will go to waste.


----------



## Docj04

We are finishing the move in process in our new home, and I have determinede that with the 20 ft catherdaral ceiling, hard wood floors--and of course, monster echo, I will be adding some treatment.


In the time that I've spent reading this thread, I've gathered that independent of the furniture in the room, I need to determine where and whether to use absorbers or diffusers, and that the application of each is subject to much debate!


At this point, It seems that the front wall should be basically panelled with absorbers(I will be ordering some 703 today). My front wall is actually a corner, with the 61" DLP flanked by 2 JBL L880 towers. Should I basically line the corner behind the TV/Stand with the 703, as well as placing one panel immediately to the side of the 2 front speakers?


As far as the remainder of the room--I was thinking that I would simply place a panel of 703 immediately behind the RIGHT rear, and 2 panels in the corner where the LEFT rear is placed. I have also considered placing a panel or two on the wall behind the sofa, at ear level.


This setup seems minimal, and does not include any diffusers. I need to keep this relatively inexpensive, and more importantly adhere to the WAF for aesthetics.


Am I waaay off??


----------



## sonart

Hi there,


You will probably need far more absorption than planned to control your reverberation time. According to ITU, Rt60 = 0,25 x (V/Vo)^1/3 where Vo = 100 m3. That's between 200 and 400 ms.


Sonart


----------



## Triaxtremec












Where the red is, I'm going 2X4 panels, will this placement work with my room configuration? Keep in mind I have moved the front speakers further from the wall as well as brought the couch closer to the front of the room by nearly 2 feet.


----------



## pepar




> Quote:
> Originally Posted by *Triaxtremec* /forum/post/15954706
> 
> 
> Where the red is, I'm going 2X4 panels, will this placement work with my room configuration? Keep in mind I have moved the front speakers further from the wall as well as brought the couch closer to the front of the room by nearly 2 feet.



It will certainly help. And you will be ahead of most people.


I know a real acoustician recommended at least 4" of absorption, but if you can place even 2" thick panels directly behind each of the front speakers - even if you have moved them away from the wall a foot or two - that would be better than nothing.


----------



## Triaxtremec

Great! Thanks, I will look further into the front panels soon but for now I can enjoy what I have.


----------



## pepar




> Quote:
> Originally Posted by *Triaxtremec* /forum/post/15957132
> 
> 
> Great! Thanks, I will look further into the front panels soon but for *now I can enjoy what I have*.


----------



## Freddie_shreddie

Anyone using cork flooring.

How is it compared to carpet?


----------



## Dennis Erskine

For cleaning? Wear and tear? Oh, I bet you mean acoustics. For acoustics cork is a non-starter.


----------



## pepar




> Quote:
> Originally Posted by *Freddie_shreddie* /forum/post/15961990
> 
> 
> Anyone using cork flooring.
> 
> How is it compared to carpet?



Cork is - essentially - _wood_.


----------



## DevonS

Comparing the values for OC 703 and Roxul Safe n' Sound on bobgolds, they appear very similar. Is the main reason for people preferring 703 because it is rigid?


Productthickness125hz250hz500hz1000hz2000hz4000hzNRC703 plain3" (76mm)0.531.191.211.081.011.041.10Safe‘n’ Sound3" (75mm)0.520.961.181.071.051.051.05

I also posted another question in here that didn't receive any response.


----------



## pepar




> Quote:
> Originally Posted by *DevonS* /forum/post/15968349
> 
> 
> Comparing the values for OC 703 and Roxul Safe n' Sound on bobgolds, they appear very similar. Is the main reason for people preferring 703 because it is rigid?
> 
> 
> Productthickness125hz250hz500hz1000hz2000hz4000hzNRC703 plain3" (76mm)0.531.191.211.081.011.041.10Safen' Sound3" (75mm)0.520.961.181.071.051.051.05
> 
> I also posted another question in here that didn't receive any response.



For those who simply cover it, rigidity is important. For those building a frame, maybe not.


----------



## pepar




> Quote:
> Originally Posted by *DevonS* /forum/post/15791590
> 
> 
> 
> My main question is, the chunk between the insulation and light tray appears to be solid, and I've seen it as solid in nearly every soffit I've seen on here. Does it have to be solid or can that be just fabric too?
> 
> 
> So... Is this a completely horrible idea? Keeping in mind I'm going from nothing to some SnS soffits and first reflection/screen-wall treatments.



If the sound can't get to the absorber, no absorption will occur.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/15968810
> 
> 
> If the sound can't get to the absorber, no absorption will occur.



Low frequencies will pass through sealed, solid panels. But then you have a panel absorber, which is a whole 'nother beast. It typically has a narrow absorption band, which may be just the thing for one or two targeted room modes.


----------



## bernfu




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15963177
> 
> 
> For cleaning? Wear and tear? Oh, I bet you mean acoustics. For acoustics cork is a non-starter.



What does that mean? I'm curious because I have cork floors in my basement and I'm trying to decide what sort of treatments to use. Does having cork floors mean I should think about things differently.


Thanks much for your help!


Adam


----------



## bernfu

 Attachment 135614 I could use some guidance on treatment locations and speaker placement. I have my screen mounted like you see on the pic. The pic is similar to my space except the I have a wall where the table is and my screen is only 1' to the wall. As you can see, the room is actually open to one side and there is a bulkhead running along the ceiling which acts as the room differentiator. My plan for my speakers is:


Centre - under the screen on my low profile stand

Left and right fronts - mounted on the wall on either side of the screen

Left and right side - mounted on the bulkhead and the opposing wall

Left and right rear - mounted on the back wall


Does anyone see any red flags with this setup?


For treatments, I'm not sure if it's worthwhile having something on the wal on the other side of the bulkhead. I thought I'd put something on the back wall and behind either front speaker.


Thanks in advance for any insight you may be able to provide!


Adam


By the way my speakers are the KEF 3005SE set.


----------



## pepar




> Quote:
> Originally Posted by *bernfu* /forum/post/15969441
> 
> 
> I could use some guidance on treatment locations and speaker placement. I have my screen mounted like you see on the pic. The pic is similar to my space except the I have a wall where the table is and my screen is only 1' to the wall. As you can see, the room is actually open to one side and there is a bulkhead running along the ceiling which acts as the room differentiator. My plan for my speakers is:
> 
> 
> Centre - under the screen on my low profile stand
> 
> Left and right fronts - mounted on the wall on either side of the screen
> 
> Left and right side - mounted on the bulkhead and the opposing wall
> 
> Left and right rear - mounted on the back wall
> 
> 
> Does anyone see any red flags with this setup?
> 
> 
> For treatments, I'm not sure if it's worthwhile having something on the wal on the other side of the bulkhead. I thought I'd put something on the back wall and behind either front speaker.
> 
> 
> Thanks in advance for any insight you may be able to provide!
> 
> 
> Adam
> 
> 
> By the way my speakers are the KEF 3005SE set.



Pic?


----------



## bernfu




> Quote:
> Originally Posted by *pepar* /forum/post/15969607
> 
> 
> Pic?



Sorry. I messed up the attachment. Let me try that again.

Attachment 135618


----------



## pepar




> Quote:
> Originally Posted by *bernfu* /forum/post/15969628
> 
> 
> Sorry. I messed up the attachment. Let me try that again.
> 
> Attachment 135618



Nice. Have a floor plan?


----------



## bernfu

floorplan
Attachment 135622


----------



## R Harkness

Whew, the ground beneath my reno keeps shifting as some possibilities get squashed and new ones arise, for instance for acoustic treatment.


I had a visit from a representative from "Whisper Walls."

http://www.whisperwalls.com/default....WhisperCeiling 



As I've mentioned earlier in this thread we have dropped a bulkhead ceiling starting over the screen wall and covering the seating area. I want the dropped portion of the ceiling bulkhead to be covered in a fabric for two reasons. One, for light absorption from the screen and a nice aesthetic look and Two, to possibly hide some acoustic absorption material in the ceiling.


The rep gave some interesting suggestions. Their fabric system (like some others such as fabricmate) use a track system. The track is laid in whatever shape, around the perimeter of where you want fabric to to. Then the big sheets of fabric are tucked into the track (using a tucking tool) to be held firm. Once the fabric is tucked into all of the track the fabric is taught and straight, looking like a straight ceiling.


This gives an intriguing possibility. At this stage the dropped bulkhead/ceiling is only framed and not dry-walled. Instead of drywalling any of the ceiling I could simply have the fabric stretched over the existing framing, and so I could put acoustic absorption wherever I want.


Also, at this point the screen wall is actually being re-constructed, so the screen wall drywall is taken down leaving a huge open cavity. The Whisper Wall guy said I don't have to drywall that screen wall and could simply fill it with accoustic material that would make the screen area a big sound absorber. (The main issue being the bass frequencies of my speakers which are near the screen and room corners). Here is an image I made indicating the current opportunity. All the blue areas (including the screen wall) indicate cavities into which I could place acoustic absorption:











The issue is that, while I want to control the bass frequencies of my speakers, I also I don't want a room that sounds too muffled or too dead.

I will have a fair amount of curtains, a big wall to wall shag rug, a big sectional sofa, and light fabric wall covering.


Also, I generally like the sound of my speakers except for the bass bloat happening now that they are in the room corners. I'm wondering of doing all this acoustic absorption might change their sound substantially...perhaps make them sound anemic or over-emphasize the highs or midrange?


I'm considering putting acoustic material behind the screen, along the bulkhead directly above the screen, and perhaps some in the center ceiling area to cover that "first reflection" point.


----------



## DevonS




> Quote:
> Originally Posted by *pepar* /forum/post/15968810
> 
> 
> If the sound can't get to the absorber, no absorption will occur.



The bottom is open with the exception of the odd brace to hold it all together (covered with fabric, of course). I'm just curious if I'm creating another little bass hide-out in the new little corner where my soffit will meet my ceiling.


----------



## (Berk)




> Quote:
> Originally Posted by *pepar* /forum/post/15954985
> 
> 
> It will certainly help. And you will be ahead of most people.
> 
> 
> I know a real acoustician recommended at least 4" of absorption, but if you can place even 2" thick panels directly behind each of the front speakers - even if you have moved them away from the wall a foot or two - that would be better than nothing.



Does it make a difference if your LCR speakers are front or rear ported? I have front ports so I'm wondering if I should treat directly behind the speakers?


----------



## penngray

cheap 18" driver in a sonotube, has an effect on really low specific frequencies.


Is it a good addition to my room? I can get some 18" drivers extremely cheap and I have sonotube so I was wondering if I could try and build something to add control to my ULF (40Hz - 80Hz range).


I already have the wall treatements and big corner tri-traps.


----------



## pepar




> Quote:
> Originally Posted by *DevonS* /forum/post/15970166
> 
> 
> The bottom is open with the exception of the odd brace to hold it all together (covered with fabric, of course). I'm just curious if I'm creating another little bass hide-out in the new little corner where my soffit will meet my ceiling.



If it's that little, the bass won't be able to hide out there.


----------



## Steve Smith

Is anyone familiar with Fab-Trax? I'm looking for something to use on inside edges between the wall panels and columns. The other track systems I've seen are one piece and the plastic edge that hooks to the latch is left exposed. This is a two piece design that's hidden and supposedly easier to install. The down side is that it's quite expensive. It's only available in beige, I wonder if the track will show through GOM fabric.

http://www.cascadeaudio.com/commerci...-Trax_Data.pdf 

http://www.cascadeaudio.com/commerci...ax_Install.pdf


----------



## pepar




> Quote:
> Originally Posted by *(Berk)* /forum/post/15973169
> 
> 
> Does it make a difference if your LCR speakers are front or rear ported? I have front ports so I'm wondering if I should treat directly behind the speakers?



We're not talking Bose 901's here are we?







Speakers, with or without rear ports, all radiate some sound from the cabinets themselves. When you see cabinets with ""clipped" (45 degree) edges, that is the designer's way of lessening the radiation; the sound likes to jump off of sharp edges. Treatments on the wall behind the speakers absorbs this radiated sound.


----------



## Freddie_shreddie




> Quote:
> Originally Posted by *pepar* /forum/post/15966236
> 
> 
> Cork is - essentially - _wood_.



I heard that it is way better than standard hardwood floor for acoustics. Doesn't really make sense to me.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Freddie_shreddie* /forum/post/15978192
> 
> 
> I heard that it is way better than standard hardwood floor for acoustics. Doesn't really make sense to me.



Cork flooring is way better than hardwood for impact noise. That is, footfall noise from it is quite low, as from carpet. But that's about it.


This fact is frequently simplified/misunderstood/misstated by sellers of cork floors as "better acoustics."


Regards,

Terry


----------



## SteveMo




> Quote:
> Originally Posted by *Freddie_shreddie* /forum/post/15978192
> 
> 
> I heard that it is way better than standard hardwood floor for acoustics. Doesn't really make sense to me.



That is also M&M #5 (not the chocolate candy) in this link.

http://www.cedia.net/homeowners/acoustical2.php


----------



## imuesmail

1. I have ordered some 2" Rockwool 80 (8ib density)---is this adequate to use for use for first reflections or should I double them up for 4" thickness?

http://www.acoustimac.com/index.php?...mart&Itemid=21 


Thanks in advance--I am still on page three of this thread.


Imu


----------



## Terry Montlick




> Quote:
> Originally Posted by *imuesmail* /forum/post/15979044
> 
> 
> 1. I have ordered some 2" Rockwool 80 (8ib density)---is this adequate to use for use for first reflections or should I double them up for 4" thickness?
> 
> http://www.acoustimac.com/index.php?...mart&Itemid=21
> 
> 
> Thanks in advance--I am still on page three of this thread.
> 
> 
> Imu



8 pcf density rockwool? Yikes, that stuff has really high flow resistivity! I think its absorption of frequencies in the low couple of kHz to the 90% point will be marginal at best. And that is what you need to achieve reflections which are the recommended 10 dB down. Doubling the thickness to 4" won't help with those frequencies, either.


----------



## R Harkness

So Terry, what material do you suggest for treating first reflections? I may put something on my ceiling at the first reflection point. Thanks.


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/15980539
> 
> 
> So Terry, what material do you suggest for treating first reflections? I may put something on my ceiling at the first reflection point. Thanks.



The same material that has been successfully used for many decades -- fiberglass, with a density in the range of 2.25 to 6 pcf. Or rockwool, but no more than 5 pcf. Its acoustic resistivity shoots up rather drastically above this point. Oh, and acoustic cotton in the same density range as fiberglass will perform as well. That shouldn't limit your choice too much.










Regards,

Terry


----------



## bernfu




> Quote:
> Originally Posted by *bernfu* /forum/post/15969937
> 
> 
> floorplan
> Attachment 135622



Is it possible to get some guidance on acoustical treatments for my room? My floorplan is pretty elementary so I'm not sure if I've given enough info. My floors are cork. The walls are drywall. And I have a large brick fireplace. I'm using the KEF KHT3005SE system with 2 extra rear speakers.


Any guidance would be appreciated.


All the best,


Adam


----------



## R Harkness

Thanks again Terry. That info is very timely for my HT project.


----------



## imuesmail




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15979316
> 
> 
> 8 pcf density rockwool? Yikes, that stuff has really high flow resistivity! I think its absorption of frequencies in the low couple of kHz to the 90% point will be marginal at best. And that is what you need to achieve reflections which are the recommended 10 dB down. Doubling the thickness to 4" won't help with those frequencies, either.



Thanks--not what I wanted to hear. I should have ordered the cheaper stuff (Rockwool 60 or 40). I will try the 80 for first reflections and hope for the best. Their website gave good specifications in terms of absorption saying it was equivalent to OC 705.


Imu


----------



## Terry Montlick




> Quote:
> Originally Posted by *imuesmail* /forum/post/15982336
> 
> 
> Thanks--not what I wanted to hear. I should have ordered the cheaper stuff (Rockwool 60 or 40). I will try the 80 for first reflections and hope for the best. Their website gave good specifications in terms of absorption saying it was equivalent to OC 705.
> 
> 
> Imu



Sorry, Imu.


Can you give me a link to the specific URL where they claim that the two products are acoustically equivalent? It doesn't hurt for me to at least try to set a manufacturer straight.


- Terry


----------



## imuesmail




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/15982417
> 
> 
> Sorry, Imu.
> 
> 
> Can you give me a link to the specific URL where they claim that the two products are acoustically equivalent? It doesn't hurt for me to at least try to set a manufacturer straight.
> 
> 
> - Terry




Thanks Terry,

Its acoustimac.com and the link is below---click on the details and they have a table listing the absorption characteristics.

http://www.acoustimac.com/index.php?...hk=1&Itemid=21 


"Our Mineral 1280 is sonically comparable to Owens Corning 705. It absorbs as much bass, has similar characteristics but costs a fraction of the price. It is typically used to build bass traps and acoustic panels with a hard frame around it for support, as it is slightly less rigid than Owens Corning 705".


HZ 125 250 500 1000 2000 4000 NRC

MNW-1280 (2")

0.32 0.90 1.11 1.07 1.01 1.05 1.05

4" THICK 1.11 0.91 1.10 1.03 1.06 1.07 1.05


thanks again

Imu


----------



## unclepauly

Alright I've made some frames for some acoustic panels now my question is if I should put just fabric on the back or some kind of wood backing? Also how far should the panel be from the wall, I was thinking about 2-4"?


----------



## pepar




> Quote:
> Originally Posted by *unclepauly* /forum/post/15990739
> 
> 
> Alright I've made some frames for some acoustic panels now my question is if I should put just fabric on the back or some kind of wood backing? Also how far should the panel be from the wall, I was thinking about 2-4"?



Good luck on deciding on that.










I have mine mounted directly on the wall. I think the reason for standing them off is to lower the frequency at which they absorb, but I have bass trap(s?) for the lower frequencies and moving them out from the wall would have encroached more into the space. YMMV.


----------



## firebrick

The front of my dedicated theater is very live, you can hear multiple high pitched echos if you clap you hands in the front of the room. Will putting 2x4 gik panels on the side walls help make my speakers sound better? The room is 25x15, I am thinking of buying 6 panels, 3 on each side, starting at the first reflection point. I think my sound is great right now but I was wondering if it would be better by reducing this echo.


----------



## Dennis Erskine

If you're standing at the front of the room clapping, you're hearing flutter echo or slap echo which would require treating the front or back wall (best the front since it will help deal with SBIR). This little test isn't saying much of anything about side wall reflections; but, yes, treatment would help your room sound better (the output of the speakers won't change a twit...what you hear in the room will change a lot).


[Clapping doesn't tell you much ... your speakers are at the front of the room, your ears at the middle to rear of the room; but, when clapping your hands the sound source and sink are in the same place in the room; but, OK, you've got a problem. Enjoy getting acquainted with fiberglass panels.]


----------



## unclepauly




> Quote:
> Originally Posted by *pepar* /forum/post/15991954
> 
> 
> Good luck on deciding on that.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have mine mounted directly on the wall. I think the reason for standing them off is to lower the frequency at which they absorb, but I have bass trap(s?) for the lower frequencies and moving them out from the wall would have encroached more into the space. YMMV.



I was hoping I wouldn't get an answer like that.







Well, at least I now know the reason for spacing them a bit.



As far as building a cloud, I figure it's basically the same principle as the acoustic panels, except bigger and hanging from the ceiling. Would I be close in this assumption?


----------



## firebrick

I figured it was the side walls because they are just drywall with no coverings. As you walk towards the back of the room the sound changes alot, it is basically dead in the back compared to the front. When I am listening, for example to a sacd in my main seating position, and press pause, I can always here the echo of the last note for a split second, very high pitched. The front of the room has two floor to ceiling superchunk bass traps and 2 velvet curtains but no other treatment.


----------



## csamos




> Quote:
> Originally Posted by *firebrick* /forum/post/15992113
> 
> 
> The front of my dedicated theater is very live, you can hear multiple high pitched echos if you clap you hands in the front of the room. Will putting 2x4 gik panels on the side walls help make my speakers sound better? The room is 25x15, I am thinking of buying 6 panels, 3 on each side, starting at the first reflection point. I think my sound is great right now but I was wondering if it would be better by reducing this echo.



Read this great article on acoustic treatment and design .


There is a section on optimizing the air gap in particular that says:


"For a given thickness of absorbent material, the ideal air gap is equal to that thickness because it avoids a hole in the range of frequencies absorbed."


To locate the first reflection points on the side walls (and ceiling) treat each wall as a mirror and use geometry (or an actual mirror) to locate each speaker as if you could see it reflecting off the wall from each listening position. It's easier with with someone else to hold a mirror up against the wall while you sit in a chair and have that person move the mirror around until you can see each speaker in the mirror. Put a piece of blue painters tape on the wall at each spot. You'll see a cluster of tape. That's where you'll want to put the panels.


Putting acoustic panels at all of the first reflection points will definitely improve the sound quality in your room. It made a big difference in my theater, and I recommend it to anyone who has a live room.


----------



## Terry Montlick




> Quote:
> Originally Posted by *csamos* /forum/post/15994788
> 
> 
> "For a given thickness of absorbent material, the ideal air gap is equal to that thickness because it avoids a hole in the range of frequencies absorbed."



???


A given thickness of absorber will absorb more at lower frequencies the farther it is spaced away from the wall. It does this at the expense of "ripple" in the absorption frequency response. This ripple is greatest for sound waves at zero angle of incidence, but comparatively much less for diffuse sound -- sound which is averaged over all angles of incidence.


Regards,

Terry


----------



## pepar




> Quote:
> Originally Posted by *unclepauly* /forum/post/15994564
> 
> 
> I was hoping I wouldn't get an answer like that.
> 
> 
> 
> 
> 
> 
> 
> Well, at least I now know the reason for spacing them a bit.
> 
> 
> 
> As far as building a cloud, I figure it's basically the same principle as the acoustic panels, except bigger and hanging from the ceiling. Would I be close in this assumption?



Sound doesn't know up or down, front or back or left or right.


----------



## csamos

All 8 posts by the previous poster nopq938 are complete nonsense/spam. Can someone delete that account?


----------



## kappa7krazy

I have an odd shaped small room that I need help with. I have 5 pieces of 3" 703 left and would like to know the best places to put them based on the shape and size of my room. I have already added some, but I don't have the tools to do any measurement with, so I am just going by ear. I have my pics in photobucket, but I am unclear as how to add them to my post. If I could get some help with that, I think it would make things alot easier. Thank you, Brian.


----------



## kappa7krazy

Ok, I think I figured it out.

nope, I guess not


----------



## kappa7krazy

Here we go. This should take you to my gallery
http://img99.imageshack.us/gal.php?g=img0123k.jpg 

Front wall is 13'

Left wall is 14'

Rear wall is 15.5'

Right wall is 5' to where it opens to the doorway. I hope this is enough info to get some ideas on what would be the best use of the remaining 5 pieces of 703. Any help would be greatly appreciated, Brian


----------



## pepar




> Quote:
> Originally Posted by *kappa7krazy* /forum/post/16017476
> 
> 
> Here we go. This should take you to my gallery
> http://img99.imageshack.us/gal.php?g=img0123k.jpg
> 
> Front wall is 13'
> 
> Left wall is 14'
> 
> Rear wall is 15.5'
> 
> Right wall is 5' to where it opens to the doorway. I hope this is enough info to get some ideas on what would be the best use of the remaining 5 pieces of 703. Any help would be greatly appreciated, Brian



Floor-to-ceiling with the "across-the-corner" panels would be an improvement over what you have now.


----------



## kappa7krazy

Cool, thanks for the reply. What I have in mind, is to glue 2 pieces side by side and then make 2 3' equilateral triangles to put up in the tri-corners on the front wall. Then possibly one piece at the front wall ceiling junction. That would leave me 2 pieces. Is it possible to over dampen a small room? TIA, Brian


----------



## pepar




> Quote:
> Originally Posted by *kappa7krazy* /forum/post/16019254
> 
> 
> Cool, thanks for the reply. What I have in mind, is to glue 2 pieces side by side and then make 2 3' equilateral triangles to put up in the tri-corners on the front wall. Then possibly one piece at the front wall ceiling junction. That would leave me 2 pieces. Is it possible to over dampen a small room? TIA, Brian



Side by side? You mean end to end, don't you? Anyway, I don't think you can glue 703 pieces together.


Yes, if you can, take advantage of the "corner" formed by the ceiling with a wall. Too many only consider a wall/wall juncture a corner.


----------



## kappa7krazy

I'm thinking if I glue them side by side, that will give me a 4' square and from that I could get my 2 triangles. I was hoping that some 3M spray adhesive would hold good enough for me to get the triangles cut and then once in their frames all would be fine. What do you think? What else could you recommend for the use of the remaining pieces. Would it be best to just focus on the front wall or should I consider the rear wall/rear wall ceiling junction. It will be a while before I am able to afford any more material so I am trying to make the best of what I have. Brian


----------



## pepar




> Quote:
> Originally Posted by *kappa7krazy* /forum/post/16019827
> 
> 
> I'm thinking if I glue them side by side, that will give me a 4' square and from that I could get my 2 triangles. I was hoping that some 3M spray adhesive would hold good enough for me to get the triangles cut and then once in their frames all would be fine. What do you think? What else could you recommend for the use of the remaining pieces. Would it be best to just focus on the front wall or should I consider the rear wall/rear wall ceiling junction. It will be a while before I am able to afford any more material so I am trying to make the best of what I have. Brian



Bass is usually a big problem in home theaters. But dialog intelligibility can suffer from early reflections, i.e. sound reflecting off of the ceiling, walls and floor, and too much reverberance. More bass traps - the corner mounted things - will help with reverberance, so you get two birds with one shot.


You need to listen to your system for the things I mentioned and decide where to use your additional resources.


You can glue two panels edge to edge, but they will break apart exactly at the spot where the adhesive penetrated no further. . . .


----------



## kappa7krazy

Thanks for the help. I think I will try to rig someting up to experiment with the extra pieces in different spots. But I will definitly get someting up in the front tri-corners. I do wish my sound card worked with rew, it would be nice to see what kind of response I have in room and the difference the panels make. Brian


----------



## pepar




> Quote:
> Originally Posted by *kappa7krazy* /forum/post/16020302
> 
> 
> Thanks for the help. I think I will try to rig someting up to experiment with the extra pieces in different spots. But I will definitly get someting up in the front tri-corners. I do wish my sound card worked with rew, it would be nice to see what kind of response I have in room and the difference the panels make. Brian



Sound card not bi-directional?


----------



## kappa7krazy

Unfortunately no. I would invest in a new sound card but since times are tight that is something that will just have to wait.


----------



## kappa7krazy

Not to go off topic of this thread, but I have been thinking about selling some of my vintage speakers and using those funds for my main listening room. What sound card would you recommend, best bang for the buck? Brian


----------



## pepar




> Quote:
> Originally Posted by *kappa7krazy* /forum/post/16020912
> 
> 
> Not to go off topic of this thread, but I have been thinking about selling some of my vintage speakers and using those funds for my main listening room. What sound card would you recommend, best bang for the buck? Brian



The way REW works, it "works around" any non-linearity in the sound card's response, so the lowest priced Creative Labs/Soundblaster with bi-directional operation will work for REW use. Spending more, of course, will get you better sound quality for music, games and those little system event sounds.


----------



## kappa7krazy

Sounds good! I have a ps3 for the games and I stream my music to it anyways so a new card might be possible. Thanks again, Brian


----------



## R Harkness

Folks,

*Does anyone here know of some acoustically transparent material that does not stretch?*


I'm integrating my home theater into an existing living room and have been working at designing in light reflections control in as discrete manner as possible. I'm going dark with the rug, dark with the ceiling, but the walls have to be left fairly light. I have curtains that will be able to be pulled to cover a portion of the light walls for movie watching, but I'm going to other strategies for other portions of the wall.


I'm using an automated roller panel system as part of my light-reflection control. There will be a roller panel over the bright wall of a fireplace near the screen and the panel will roll down (matte black) to cover the wall when watching a movie.


I want to do the same thing on another portion of the wall but the issue is that it will have a side channel speaker on that wall. So the standard materials that come with the roller shades will block the sound. I'd like to replace the standard material with acoustically transparent material. However, my supplier for the roller shades tells me I'd better be able to find a fabric that does not stretch much at all, or after time it's going to run into trouble as it rolls up and down.


Any suggestions for such a material?


Thanks,


----------



## rigman

Hi can anyone tell me how they attach the OC 703 to their walls.


I have the British equivalent (well 1" 60kg density rockwool) but was wondering what was the best way to fix it. Glue, nails, screws?










thanks for any help

Darren


----------



## pepar




> Quote:
> Originally Posted by *rigman* /forum/post/16062820
> 
> 
> Hi can anyone tell me how they attach the OC 703 to their walls.
> 
> 
> I have the British equivalent (well 1" 60kg density rockwool) but was wondering what was the best way to fix it. Glue, nails, screws?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> thanks for any help
> 
> Darren



I made panels with frames and a backer, and then used angle brackets to mount same to the wall (and the ceiling). Check the link in my sig.


----------



## rigman

Hi there thanks for the reply but I want to stick the material direct to the wall rather than build it into frames.


I will be covering it with black speaker cloth though.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *rigman* /forum/post/16070344
> 
> 
> Hi there thanks for the reply but I want to stick the material direct to the wall rather than build it into frames.
> 
> 
> I will be covering it with black speaker cloth though.



I use the RotoFast connectors. http://www.rotofast.com/


----------



## pepar




> Quote:
> Originally Posted by *rigman* /forum/post/16070344
> 
> 
> Hi there thanks for the reply but I want to stick the material direct to the wall rather than build it into frames.
> 
> 
> I will be covering it with black speaker cloth though.



It doesn't seem dense enough to hold its own weight.


----------



## myfipie




> Quote:
> Originally Posted by *kappa7krazy* /forum/post/16012717
> 
> 
> I have already added some, but I don't have the tools to do any measurement with, so I am just going by ear.



This will give you the tools to measure the room. The best part is it is free.

http://www.hometheatershack.com/roomeq/ 


Glenn


----------



## Weasel9992




> Quote:
> Originally Posted by *myfipie* /forum/post/16075921
> 
> 
> This will give you the tools to measure the room. The best part is it is free.
> 
> http://www.hometheatershack.com/roomeq/
> 
> 
> Glenn



You'll have to add a measurement mic like the ECM8000 from Behringer or the RTA-M by DBX (what I use). The first one is maybe $50...the RTA-M is about $85 most places. You'll also need an audio interface or a soundcard that supports it, but most do.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16077291
> 
> 
> You'll have to add a measurement mic like the ECM8000 from Behringer or the RTA-M by DBX (what I use). The first one is maybe $50...the RTA-M is about $85 most places. You'll also need an audio interface or *a soundcard that supports it, but most do.*



Bi-directional operation is the feature to look for . . .


----------



## kappa7krazy

Thanks for those suggestions. I do have a rat shack spl meter but my sound card is not bi-directional. I am in the process of finishing off the last 5 sheets of 3" 703 focusing mainly on the back wall. I do plan on purchasing the outlaw 997 when it comes out which has the trinnov room correction. I believe trinnov will have the ability to show me my in room response when connected to the computer. If this is the case, no need to spend money elsewhere. Brian


----------



## firebrick

I have two floor to ceiling superchunk bass traps in the front corners of my room. There is no way I can put traps in the corners of the rear of my room. I was thinking of adding one of the 6" thick bass traps to the center of my rear wall. Will this help control bass even better since i have no treatments in the rear of the room? Ive read alot of people put diffusion on the back wall so i didnt know if putting a bass trap there was good or not. Thanks.


----------



## pepar




> Quote:
> Originally Posted by *firebrick* /forum/post/16131362
> 
> 
> I have two floor to ceiling superchunk bass traps in the front corners of my room. There is no way I can put traps in the corners of the rear of my room. I was thinking of adding one of the 6" thick bass traps to the center of my rear wall. Will this help control bass even better since i have no treatments in the rear of the room? Ive read alot of people put diffusion on the back wall so i didnt know if putting a bass trap there was good or not. Thanks.



The real bang for buck is in the corners. How about the corner formed by the front wall and the ceiling? That counts, too.


----------



## firebrick




> Quote:
> Originally Posted by *pepar* /forum/post/16131453
> 
> 
> The real bang for buck is in the corners. How about the corner formed by the front wall and the ceiling? That counts, too.



I am trying to figure out a plan to do that. So do you think placing one on the wall in the back would be a waste?


----------



## pepar




> Quote:
> Originally Posted by *firebrick* /forum/post/16131729
> 
> 
> I am trying to figure out a plan to do that. So do you think placing one on the wall in the back would be a waste?



I didn't say it would be a waste.







How about the corner formed by the rear wall and the ceiling?


----------



## Terry Montlick




> Quote:
> Originally Posted by *firebrick* /forum/post/16131729
> 
> 
> I am trying to figure out a plan to do that. So do you think placing one on the wall in the back would be a waste?



It helps to know what you are trying to treat. A floor to ceiling absorber in the center of the back wall can be effective on lengthwise room modes, but only on half (the even ones) of the widthwise room modes.


----------



## firebrick




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16132192
> 
> 
> It helps to know what you are trying to treat. A floor to ceiling absorber in the center of the back wall can be effective on lengthwise room modes, but only on half (the even ones) of the widthwise room modes.



I am just trying get an optimal room setup, I did the front corners and read the back corners should be done as well, since i cant do that i am thinking of the trap in the center of the wall.


----------



## cinema mad

If you want optimal room treatment placment & the biggest impact on your sound quality, As pepar stated you must treat all 4 corners floor to ceiling with broadband bass traps 4"-6" thick any thing else is just A compromise untill this is accomplished ...


Cheers....


----------



## firebrick




> Quote:
> Originally Posted by *cinema mad* /forum/post/16132613
> 
> 
> If you want optimal room treatment placment & the biggest impact on your sound quality, As pepar stated you must treat all 4 corners floor to ceiling with broadband bass traps 4"-6" thick any thing else is just A compromise untill this is accomplished ...
> 
> 
> Cheers....



I am trying to state that there are no corners to treat. The door is on the one corner and the equipment cabinet is on the other. The rear of the room is not square the walls come together at 45degree angles. Thats why I am asking whether or not it would be worth it to put the trap in the middle of the rear wall. This is the only place it can go in the rear of the room.


----------



## pepar




> Quote:
> Originally Posted by *firebrick* /forum/post/16133066
> 
> 
> I am trying to state that there are no corners to treat. The door is on the one corner and the equipment cabinet is on the other. The rear of the room is not square the walls come together at 45degree angles. Thats why I am asking whether or not it would be worth it to put the trap in the middle of the rear wall. This is the only place it can go in the rear of the room.



Then put one there.


----------



## AnthemAVM

Is GIK the only company that makes a Tri-Trap Bass Trap?


----------



## pepar




> Quote:
> Originally Posted by *AnthemAVM* /forum/post/16133201
> 
> 
> Is GIK the only company that makes a Tri-Trap Bass Trap?



I believe that is one of their product names.


----------



## nathan_h

Real Traps makes something called a "Tri-Corners" trap.


----------



## pepar

The designs are far from proprietary, but everyone has their own names.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16133138
> 
> 
> Then put one there.



I agree. As I pointed out, it helps a lot if you have some measurements to know if this will have any positive effect on treating your room's modes. But if you want one there, by all means, add it! If is a full-range porous absorber (no covering layer) and not just limited to bass, it will likely have other beneficial acoustical effects.


- Terry


----------



## Frank D

Here is another place thast sells bags for corner traps if you want to make some on your own and save a few bucks:

http://www.readyacoustics.com/index....ls&prod=RT426B


----------



## derekintexas

Sorry to interrupt, but I just finished researching the various materials used for acoustic treatments including bass traps, etc... I decided on OC 703 and just bought some and I figured I'd post where I got it from and what I paid to help out any fellow North Texas people (Dallas / Fort Worth) that also choose to go this route. Sorry if I posted it in the wrong place, it's the best place I could find. I just want to give back a little bit of helpful info to this community.


Their website is easy to google but the forum won't let me post it since I'm newly registered (this is my first post actually).


Specialty Products & Insulation Co (SPI-CO)

11232 Leo Lane

Dallas, TX 75229

(800) 927-7742


I bought:


480sf of OC703 2" thick (unfaced) 2x24x48 at $0.84 per square foot

this comes 12 panels to the bundle so I bought 5 bundles


192sf of OC703 1" thick (unfaced) 1x24x48 at $0.42 per square foot

this comes 24 panels to the bundle so I bought 1 bundle


My subtotal was $483.84 plus $39.91 sales tax so grand total $523.75. I know there have been plenty of posts that discuss places to purchase this material but I figured it always helps to have some recent information. Plus, I had never seen anyone mention such a cheap price for the 1" thickness. It's half the thickness and therefore half the price. Most (if not all) other places charge substantially more than this for the 1" stuff. They have other locations in the metrolplex (and nationwide for that matter). This location usually has lots in stock. The Fort Worth location would have transferred some over free of charge but it's Friday and I want to get some work accomplished this weekend so I drove over to Dallas to pick it up. By the way, if you're buying as much as I did, drive your truck (obviously) and don't forget to bring straps, rope, etc... (don't ask me how I know)










I have no affiliation with them whatsoever, but finally decided to post some helpful information since I have spent MONTHS of my time on here reading thousands of posts from other helpful people.


I now return you to your normal broadcasting.










Derek


----------



## pepar

SPI is part of the thread's collective wisdom and the pricing in line with what I paid a few years ago. They actually have locations all over the country.


----------



## jagerbombster

For those of you who have used 3m or other spray adhesive to attach your treatments (OC703) how much was enough?


I'm looking at attaching almost 600sqft and looking at $25/can. Wondering how far a can will go. Wondering if rotofast might be cheaper?


Thanks


----------



## yngdiego




> Quote:
> Originally Posted by *jagerbombster* /forum/post/16139611
> 
> 
> For those of you who have used 3m or other spray adhesive to attach your treatments (OC703) how much was enough?
> 
> 
> I'm looking at attaching almost 600sqft and looking at $25/can. Wondering how far a can will go. Wondering if rotofast might be cheaper?
> 
> 
> Thanks



I use rotofast for my wall and ceiling panels. They work great and only require a few small screw holes. I can't even imagine gluing panels to any permanent surface.


----------



## pepar

And I don't think 703 is dense enough to hold its own weight with applying adhesive directly to it.


----------



## Fabricator

hello, gents. just found this thread.


my questions ?


when using MCACC. looking at the adjustments it makes, is that a way to get an idea of what area/s need treatments ?


i am sure there is a "good" & "waist of effort" material list in here somewhere.

can someone point me to its direction ? thanx a ton.


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16143118
> 
> 
> And I don't think 703 is dense enough to hold its own weight with applying adhesive directly to it.



ya, I'm going to build a small frame around all of mine so the material is actually attached to the frame and the 703 just kinda floats behind it within the frame.


----------



## pepar




> Quote:
> Originally Posted by *will1383* /forum/post/16148491
> 
> 
> ya, I'm going to build a small frame around all of mine so the material is actually attached to the frame and the 703 just kinda floats behind it within the frame.



You can adhere the 703 to the inside of the frame, or to the backer if you have one, and then use fasteners from the frame to the wall. I did mine that way after covering with GOM.


----------



## (Berk)

Hi all, Thanks to all the great advice I got here my HT has come along nicely in the last couple weeks. I was trying to start a build thread but I am having problems posting pictures. I'll try to work on it again soon, but my 'puter with all the pics on it is having some other issues now tool. Once I get it fixed I'll give it another try. In the meantime, does anyone have any suggestions on how to stop sound from going through the HVAC ducts? My room is almost completely sound proof but I can hear sound coming into the room through the ducts. I'd hate to have spent all this time, effort and money and not be able to fix this problem. Is there something that you can do to the ducts that restricts sound without killing the airflow?


Thanks,

Berk


----------



## pepar




> Quote:
> Originally Posted by *(Berk)* /forum/post/16152216
> 
> 
> Hi all, Thanks to all the great advice I got here my HT has come along nicely in the last couple weeks. I was trying to start a build thread but I am having problems posting pictures. I'll try to work on it again soon, but my 'puter with all the pics on it is having some other issues now tool. Once I get it fixed I'll give it another try. In the meantime, does anyone have any suggestions on how to stop sound from going through the HVAC ducts? My room is almost completely sound proof but I can hear sound coming into the room through the ducts. I'd hate to have spent all this time, effort and money and not be able to fix this problem. Is there something that you can do to the ducts that restricts sound without killing the airflow?



Duct liner. Not real practical to retrofit though.


----------



## rigman

Hi all


my new room will be 20' x 12' I plan to cover the screen wall in 4" auralex wedges and Lenrds corner base traps. The side wall will have 1" rockwool from about 1' up to 4' up covered with acoustically transparent cloth.


What should I do with the back wall. I have a 7.1 system with 2 speakers alongside the seats and 2 at the rear around 7' apart. The side speakers are tripoles (M&K SS-150)and the rear speakers are direct front firing (M&K S-85).


The rear settee will be on a 11" riser and there is a heat radiator in the lower centre of the rear wall. I was going to leave the wall untreated (as most of the area will be blocked by the settee and riser) but now reading various reports to others I am confused.


I can have anything on that wall to a 1" depth so should I go for more rockwool or should I go for diffusion tiles to diffuse the rear sound stage.


thanks very much for any help

Darren


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16148808
> 
> 
> You can adhere the 703 to the inside of the frame, or to the backer if you have one, and then use fasteners from the frame to the wall. I did mine that way after covering with GOM.




Right. the only thing is that with my wall being floating (I used RISC clips and/ green glue) I want to minimize the number of fastener holes I have to use to attach stuff to the walls, so I'm going to basically attach some "posts" at the proper weight bearing areas, and then build the frame and attach it to that. Then I think I'm going to attach the gom to that frame, and loosely attach the 703 behind it.


The 703 I'm putting up is 4'x8', 2" thick sheets, and I'm going to double layer them for a total of 4" of 703 material. That should be enough to kill the front wall reflections.


This is just for my front wall, which is going to have an AT screen hung in front of the material.


----------



## nathan_h




> Quote:
> Originally Posted by *Frank D* /forum/post/16134896
> 
> 
> Here is another place thast sells bags for corner traps if you want to make some on your own and save a few bucks:
> 
> http://www.readyacoustics.com/index....ls&prod=RT426B



Another quality resource:

http://sensiblesoundsolutions.com/ 


In fact, they had slightly better prices on several things I was shopping for.


----------



## nathan_h




> Quote:
> Originally Posted by *rigman* /forum/post/16153072
> 
> 
> Hi all
> 
> 
> my new room will be 20' x 12' I plan to cover the screen wall in 4" auralex wedges and Lenrds corner base traps. The side wall will have 1" rockwool from about 1' up to 4' up covered with acoustically transparent cloth.



If it's not already a done deal, I'd recommend buying fiberglass panels/traps instead of the foam ones. In less space, and about the same price, you'll get far more effective treatments.


----------



## rigman

It is an already done deal. it is stuff I had in my old house and old room which I am re-using. I may double stack it so the wedges merge together to give me a more effective treatment as i have more than what I need. this stuff was very expensive at the time and I am loath to throw it away.


I also plan to build some soffits and fill with rockwool. My other base trap will now be my riser which I am going to cut some holes in the front and rear into the chambers which will also be filled with rockwool. Hopefully that should cover all the frequencies.


I have some left over Auralex DST-R's which are polystyrene diffusers. After some more research today I will place these on the rear wall behind the cloth as it cannot do any harm can it?


Now just the ceiling reflections to sort out


----------



## pepar




> Quote:
> Originally Posted by *will1383* /forum/post/16154632
> 
> 
> Right. the only thing is that with my wall being floating (I used RISC clips and/ green glue) I want to minimize the number of fastener holes I have to use to attach stuff to the walls, so I'm going to basically attach some "posts" at the proper weight bearing areas, and then build the frame and attach it to that. Then I think I'm going to attach the gom to that frame, and loosely attach the 703 behind it.
> 
> 
> The 703 I'm putting up is 4'x8', 2" thick sheets, and I'm going to double layer them for a total of 4" of 703 material. That should be enough to kill the front wall reflections.
> 
> 
> This is just for my front wall, which is going to have an AT screen hung in front of the material.



Same setup in my theater, but with 2" J-M Linacoustic on the front wall. I rely on SSC bass traps for absorption at the lower frequencies. 4" will absorb lower than 2", but it will not reach effectively to the bottom two octaves and you would need traps anyway.


Just my $.02.


See my link.


----------



## nathan_h




> Quote:
> Originally Posted by *rigman* /forum/post/16155137
> 
> 
> It is an already done deal. it is stuff I had in my old house and old room which I am re-using. I may double stack it so the wedges merge together to give me a more effective treatment as i have more than what I need. this stuff was very expensive at the time and I am loath to throw it away.



I know the feeling. I was able to sell about 3/4 of my Auralex foam on craiglist locally, and took a bit of a hit, but dumped the proceeds into fiberglass and never looked back.


But the stuff I couldn't sell, I re-used, for sure.



> Quote:
> I also plan to build some soffits and fill with rockwool. My other base trap will now be my riser which I am going to cut some holes in the front and rear into the chambers which will also be filled with rockwool. Hopefully that should cover all the frequencies.



You'll want to read up on what size and variety of holes to drill/cut into the riser. The hoel size impacts which specific frequencies are trapped -- and unless you know you have a problem in one range of frequencies and can readily focus on those, broadband bass trapping is usually preferable.



> Quote:
> I have some left over Auralex DST-R's which are polystyrene diffusers. After some more research today I will place these on the rear wall behind the cloth as it cannot do any harm can it?



My view is that diffusion is almost assuredly better than a plain wall, yes.


----------



## cavchameleon




> Quote:
> Originally Posted by *nathan_h* /forum/post/16154976
> 
> 
> Another quality resource:
> 
> http://sensiblesoundsolutions.com/
> 
> 
> In fact, they had slightly better prices on several things I was shopping for.



Great place to purchase BAC (Bonded Acoustical Cotton), which also comes in 5 1/2" bulk sheets if you want a non-fiberglass route. Bryan is a great guy to deal with there, and yes, great prices too.


Ray


----------



## rigman




> Quote:
> Originally Posted by *nathan_h* /forum/post/16155559
> 
> 
> 
> You'll want to read up on what size and variety of holes to drill/cut into the riser. The hoel size impacts which specific frequencies are trapped -- and unless you know you have a problem in one range of frequencies and can readily focus on those, broadband bass trapping is usually preferable.




Thanks Nathan










Broadband trapping does sound to be the best option.


Are there any formulas for working it out. My riser will be in 2 sections screwed together. The rear section is 8' x 4' The front section will be 8' x 2' with a step at each side. It was easier to build that way but is essentially 2 separate pieces hence the comment about cutting the holes in the front and the rear. The inernals are partitioned into 2' wide sections.


maybe I can just cut different sized holes in each section


----------



## pepar

Lemme just throw this out there - the fiberglass materials we use for treatments are mostly all from the commercial contractor HVAC and insulation world. If one has the knowledge on what to buy and who to call, one can save a boatload of money. If the word "sound" or "acoustical" appears in the company's name, the boat becomes a dinghy.


Just my $.02.


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16155315
> 
> 
> Same setup in my theater, but with 2" J-M Linacoustic on the front wall. I rely on SSC bass traps for absorption at the lower frequencies. 4" will absorb lower than 2", but it will not reach effectively to the bottom two octaves and you would need traps anyway.
> 
> Just my $.02.
> 
> See my link.



Ya, I know I really should do bass traps as the 4" won't go quite low enough, but I am literally out of room to place them, with the exception of possibly the two rear corners of the room. With the door on the front wall, and the screen covering a good portion of it, I really don't have much to work with regarding bass traps. At least not enough depth to be able to do anything.....


I'm open to suggestions, but I knew this going into my build - that bass traps were going to be near impossible to place in the front of my room...


----------



## SteveMo




> Quote:
> Originally Posted by *will1383* /forum/post/16158076
> 
> 
> Ya, I know I really should do bass traps as the 4" won't go quite low enough, but I am literally out of room to place them, with the exception of possibly the two rear corners of the room. With the door on the front wall, and the screen covering a good portion of it, I really don't have much to work with regarding bass traps. At least not enough depth to be able to do anything.....
> 
> 
> I'm open to suggestions, but I knew this going into my build - that bass traps were going to be near impossible to place in the front of my room...



Most do not have the space or funds available to go into a fully blown treated room. My advise would be to get your room the best that you can.


----------



## will1383

Are there any calculations available to show just how deep/shape/size of bass traps I would need to build in order to properly trap them?


----------



## pepar




> Quote:
> Originally Posted by *will1383* /forum/post/16158076
> 
> 
> Ya, I know I really should do bass traps as the 4" won't go quite low enough, but I am literally out of room to place them, with the exception of possibly the two rear corners of the room. With the door on the front wall, and the screen covering a good portion of it, I really don't have much to work with regarding bass traps. At least not enough depth to be able to do anything.....
> 
> 
> I'm open to suggestions, but I knew this going into my build - that bass traps were going to be near impossible to place in the front of my room...



Look up. There are corners formed by the walls and the ceiling.


----------



## pepar




> Quote:
> Originally Posted by *will1383* /forum/post/16158175
> 
> 
> Are there any calculations available to show just how deep/shape/size of bass traps I would need to build in order to properly trap them?



Mouse around here .


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16158362
> 
> 
> Look up. There are corners formed by the walls and the ceiling.



I know. I don't even that THAT much space... It is TIGHT... example:


My door is a 6' 8" door, there's only 4" of clearance between the top of the door and the ceiling. My door is shoe-horned into the front right of the room, and there's only 3" between the door and the side wall.


----------



## rutlian

Hi everyone,


I am planning to add a corner base traps, and due to a limited budget I am opting

a diagonal 4" OC703 (2" back to back together) from floor to ceilling it will be a DIY project and now my question is really about placement of my main speakers should I set my main speakers diagonal also behind the diagonal panel of it is ok facing straight towards the seating area. Thanks in advance, after treating my first reflection points the sounds improved so much that I am now ready to add corner traps.


Peter


----------



## pepar




> Quote:
> Originally Posted by *rutlian* /forum/post/16165312
> 
> 
> Hi everyone,
> 
> 
> I am planning to add a corner base traps, and due to a limited budget I am opting
> 
> a diagonal 4" OC703 (2" back to back together) from floor to ceilling it will be a DIY project and now my question is really about placement of my main speakers should I set my main speakers diagonal also behind the diagonal panel of it is ok facing straight towards the seating area. Thanks in advance, after treating my first reflection points the sounds improved so much that I am now ready to add corner traps.
> 
> 
> Peter



I think your speakers should be positioned based on where the listeners are. Or maybe I'm not understanding your question?


----------



## rutlian

Quote:

Originally Posted by *pepar* 
I think your speakers should be positioned based on where the listeners are. Or maybe I'm not understanding your question?
Well what I mean is, should my main L/R speakers slightly angled facing the listeners or is it okey if my main speakers facing straight to the back wall (not angled.)


I am planning to add corner bass traps in the screen wall.

 

corners.doc 19.5k . file


----------



## pepar




> Quote:
> Originally Posted by *rutlian* /forum/post/16165538
> 
> 
> Well what I mean is, should my main L/R speakers slightly angled facing the listeners or is it okey if my main speakers facing straight to the back wall (not angled.)



Yep, OK, I always aim my speakers at the geographical center of the listening area. Off-axis tweeter response is usually irregular and aiming is a way to spread the highs as evenly as possible.


----------



## rutlian




> Quote:
> Originally Posted by *pepar* /forum/post/16165591
> 
> 
> Yep, OK, I always aim my speakers at the geographical center of the listening area. Off-axis tweeter response is usually irregular and aiming is a way to spread the highs as evenly as possible.



Thanks Pepar, I will angled it towards the center of the listnening area thank you very much.


----------



## allredp




> Quote:
> Originally Posted by *rutlian* /forum/post/16165669
> 
> 
> Thanks Pepar, I will angled it towards the center of the listnening area thank you very much.



You might want to consult your speaker manual or the dealer/company about this question to be sure.


For example, I have Dali speakers with ribbon tweeters and they are not supposed to be angled at all (which was weird to me at first, considering my previous soft-dome tweeters); however, they sound glorious in their non-angled position!


Just check to be sure...


----------



## rutlian




> Quote:
> Originally Posted by *allredp* /forum/post/16168011
> 
> 
> You might want to consult your speaker manual or the dealer/company about this question to be sure.
> 
> 
> For example, I have Dali speakers with ribbon tweeters and they are not supposed to be angled at all (which was weird to me at first, considering my previous soft-dome tweeters); however, they sound glorious in their non-angled position!
> 
> 
> Just check to be sure...



ok thanks I check it to make sure


----------



## belzarrath

Hello, I'm sure this may have been asked before. While shopping at HD i found temple-inland soundchoice sound-deadening fiberboard for about $10 4'X8' 1/2" SHEET. I have looked at serval sites to see its acoustical absorbtion but have not found it. If anyone knows what it is or if it would be good for low frqs absorbtion please let me know.


----------



## Terry Montlick




> Quote:
> Originally Posted by *belzarrath* /forum/post/16173825
> 
> 
> Hello, I'm sure this may have been asked before. While shopping at HD i found temple-inland soundchoice sound-deadening fiberboard for about $10 4'X8' 1/2" SHEET. I have looked at serval sites to see its acoustical absorbtion but have not found it. If anyone knows what it is or if it would be good for low frqs absorbtion please let me know.



A good rule of thumb is to ignore any acoustical claims for construction materials which have "sound" anywhere in the product name.


----------



## belzarrath




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16173924
> 
> 
> A good rule of thumb is to ignore any acoustical claims for construction materials which have "sound" anywhere in the product name.



Thanks Terry,,

When ever possible I like to look at data. "Rule of thumb" is a good norm, however norms are followed as much as broken.

I was hoping someone had some tested values of the substance.



Thanks again for input,


----------



## Dennis Erskine

If the company cannot produce the results of independent certified testing results documenting the product's acoustical properties, then do not use the product. This is a sound reproduction space. Products designed for, and typically used in, noise reduction applications for human speech (offices, conference rooms, homes) are not appropriate for this application.


----------



## entrecour

Hi all,


My first post in this thread, but I have been a silent follower for a while now.


I am planning a dedicated media room and as I can't get OC703 in Sweden I have been looking at alternatives. I found some Isover Technical Insulation products which are not listed on bobgolds list, however I found the following data on their local web site (all measurements according to ISO 354)


Which, if any, of these would you recommend for use as absorption in corners / on walls? Watch the colour coding for the various thicknesses is not consistent.

Attachment 138679 

Attachment 138676 

Attachment 138677 

Attachment 138678 



Densities are between 35Kg (glass fiber) and 100Kg (mineral) per cubic meter. There is a perforated aluminum foil backing material on one side of the Cleantec Plus 6329 sheet.


It seemed to me that the Cleantec 8739 and the VVS sheet were most similar to OC703 at 2" (50mm).


----------



## jay131011

hey everyone been a long time follower of avsforum, however this is my first post im doing my own acoustical treatment in my theatre room and am still kind of confused, i found a website readyacoustics.com sent him my google sketchup (my room is 13x15 with a stage and 2nd row riser as well as soffit above stage and along back wall to house projector) and he recommeneded "If there is no acoustic treatment present, and since you are still at the "build" stage, I'd recommend adding 4" thick absorption in some key locations:



Rear Wall

Side walls

Over your seating

Front left and right corners, and behind the screen



Focusing on these areas should result is better low frequency response and tighter, more predictable sound overall.

Finding the first reflection point is as easy as sitting in your listening position and having someone slide a mirror around on your side walls until you can see the speaker (or surrogate) in that mirror.

Where you see that speaker is the point at which you apply your broadband absorber(s).

Then, installation overhead as well as immediate left and right side walls, rear wall and vertical corners. If you can get 2, 48x24x4 inch bass traps in each corner, (vertically stacked), then your making the most of that installation location. If not, straddle a single broadband absorber across that corner, and try to touch the ceiling (or floor) plus your left and right side walls at the same time. In this manner, the absorber is touching 2-3 resonant surfaces and is helping to tame all of them at once.


does this sound accurate? and also i talked to a guy at home depot about gettin owens corning 705 and he told me to get roxul safe and sound instead anyone know if that will do the trick? any info is greatly appreciated, thanks guys!


----------



## Weasel9992

Sure, that sounds accurate. You can always call them on the phone and get some clarification too.


Safe'n Sound will work fine in most places...705 is a good bit denser.


Frank


----------



## pepar

jay131011 - http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## cavchameleon




> Quote:
> Originally Posted by *pepar* /forum/post/16226991
> 
> 
> jay131011 - http://www.bobgolds.com/AbsorptionCoefficients.htm



Wow! Awesome link, thanks Pepar!


Ray


----------



## jay131011

wow thanks for the link it cleared alot up, I still have some questions though as im still pretty new to this, Ive about half of this thread and early on they say dont use 2" bc it might absorb to much, wouldnt 3" be even more absorbant? good or bad? and as first reflection points do i cover up to ear heigh or whole height of wall? also whats with everyone saying do ear height along side and rear walls, wouldnt you hit the first reflection points by doing that? I also plan to put diy base traps in the corners and some form of treatment on the tri corners where the walls meet the soffits does this sound correct? as you can tell im pretty confused haha. any info would be greatly appreciated!


----------



## Terry Montlick




> Quote:
> Originally Posted by *jay131011* /forum/post/16231755
> 
> 
> wow thanks for the link it cleared alot up, I still have some questions though as im still pretty new to this, Ive about half of this thread and early on they say dont use 2" bc it might absorb to much, wouldnt 3" be even more absorbant?



What's "bc?"

And I've always wondered what "absorb too much" meant!










Regards,

Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *jay131011* /forum/post/16231755
> 
> 
> wow thanks for the link it cleared alot up, I still have some questions though as im still pretty new to this, Ive about half of this thread and early on they say dont use 2" bc it might absorb to much, wouldnt 3" be even more absorbant? good or bad?



No...it doesn't work that way. Assuming it's the same density, it'll just extend the low end coverage of the panel. It'll absorb more down lower not more at the same frequencies.



> Quote:
> Originally Posted by *jay131011* /forum/post/16231755
> 
> 
> and as first reflection points do i cover up to ear heigh or whole height of wall? also whats with everyone saying do ear height along side and rear walls, wouldnt you hit the first reflection points by doing that?



Ear height is fine in most cases. You're looking to control reflection along the plane of the seated listener's ear.



> Quote:
> Originally Posted by *jay131011* /forum/post/16231755
> 
> 
> I also plan to put diy base traps in the corners and some form of treatment on the tri corners where the walls meet the soffits does this sound correct? as you can tell im pretty confused haha. any info would be greatly appreciated!



That sounds just fine.


Frank


----------



## Weasel9992




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16231886
> 
> 
> What's "bc?"



It's the time period before the common era, but that's neither here nor there...










Frank


----------



## Terry Montlick




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16231917
> 
> 
> It's the time period before the common era, but that's neither here nor there...



Thank you, Weasel #9992!


----------



## Ethan Winer




> Quote:
> Originally Posted by *jay131011* /forum/post/16226185
> 
> 
> i talked to a guy at home depot about gettin owens corning 705 and he told me to get roxul safe and sound instead



There are two issues - absorption and ease of use. One of the overwhelming advantages of 705 rigid fiberglass is that it's very rigid, and holds its shape well without sagging. It's also very easy to cut and make clean straight corners etc.


--Ethan


----------



## jay131011

wow thanks for all the fast responses guys! youre all helping come along a lot faster, haha bc is short for because im 21 n text alot so i use short form.. thanks for the info again


----------



## Weasel9992




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16231996
> 
> 
> There are two issues - absorption and ease of use. One of the overwhelming advantages of 705 rigid fiberglass is that it's very rigid, and holds its shape well without sagging. It's also very easy to cut and make clean straight corners etc.



Yep...the Safe'nSound will be less expensive though. Not that that matters necessarily.


Frank


----------



## entrecour




> Quote:
> Originally Posted by *entrecour* /forum/post/16188659
> 
> 
> Which, if any, of these would you recommend for use as absorption in corners / on walls? Watch the colour coding for the various thicknesses is not consistent.
> 
> Attachment 138679
> Attachment 138676
> Attachment 138677
> Attachment 138678
> 
> 
> Densities are between 35Kg (glass fiber) and 100Kg (mineral) per cubic meter. There is a perforated aluminum foil backing material on one side of the Cleantec Plus 6329 sheet.



I'd appreciate any advice on use of either of the above materials instead of OC703. Thanks!


----------



## gamelover360

I am trying to put acoustic treatments in my HT room and I have a general question. Is there any difference between the different companies panels? I have looked at Real traps, and I really like how extensive their offerings are as well as their customer service...I called with a question. But I have found cheaper alternatives, and I am wondering if certain companies use different materials? Or all they are just fiberglass? Thanks


----------



## pepar




> Quote:
> Originally Posted by *gamelover360* /forum/post/16237209
> 
> 
> I am trying to put acoustic treatments in my HT room and I have a general question. Is there any difference between the different companies panels? I have looked at Real traps, and I really like how extensive their offerings are as well as their customer service...I called with a question. But I have found cheaper alternatives, and I am wondering if certain companies use different materials? Or all they are just fiberglass? Thanks



My observation is that they all pretty much use the same materials. The differences will be in the product offerings, customer service/tech assistance and, of course, price. You need to find the balance that is most comfortable for you. Some go completely DIY, some hire a consultant for a turn-key solution and everyone else falls somewhere in between.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/16237875
> 
> 
> My observation is that they all pretty much use the same materials. The differences will be in the product offerings, customer service/tech assistance and, of course, price. You need to find the balance that is most comfortable for you. Some go completely DIY, some hire a consultant for a turn-key solution and everyone else falls somewhere in between.



Pepar pretty much nailed it on all counts. From a performance standpoint everbody's pretty similar, so it comes down to a number of other factors. There's also the option of DIY or a combination of the two.


Frank


----------



## gamelover360




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16238455
> 
> 
> Pepar pretty much nailed it on all counts. From a performance standpoint everbody's pretty similar, so it comes down to a number of other factors. There's also the option of DIY or a combination of the two.
> 
> 
> Frank



Thanks. That was my suspicion.


----------



## Dark05

I have a few questions, not sure if they have been answered before.


I'm moving and my new media room is a 10x10x8 sheet rock walled room. It has horrible flutter echo.


I have 2 questions. I don't have much to spend on acoustical treatment so is treating the first reflection point of each speaker enough to remove the flutter echo or do I need to do a completely 30-50% coverage on every wall?


I'm looking at getting the Auralex wedgies that are $5 for 1 foot squares. These look rather ugly by themselves so I was also wondering if anyone had any good ideas as far as how to make these look attractive in this small room? How to place them in a pattern or Can you paint them without removing their absorbing properties?


How many of these wedgies showed I be budgeting for?


Also there is a closet on the back wall. In that closet I have a couple shelves and I heard this can act as a poor man's diffuser and that the increased opening of the closet could help remove some reflections as is. Is this true, or am I mistaken? Would it be beneficial to just go ahead and remove those two doors? Also How should I position the wedges on the front and back wall?


Thanks for listening to these basic questions.


----------



## yngdiego




> Quote:
> Originally Posted by *Dark05* /forum/post/16251561
> 
> 
> I have a few questions, not sure if they have been answered before.
> 
> 
> I'm moving and my new media room is a 10x10x8 sheet rock walled room. It has horrible flutter echo.
> 
> 
> I have 2 questions. I don't have much to spend on acoustical treatment so is treating the first reflection point of each speaker enough to remove the flutter echo or do I need to do a completely 30-50% coverage on every wall?
> 
> 
> I'm looking at getting the Auralex wedgies that are $5 for 1 foot squares. These look rather ugly by themselves so I was also wondering if anyone had any good ideas as far as how to make these look attractive in this small room? How to place them in a pattern or Can you paint them without removing their absorbing properties?
> 
> 
> How many of these wedgies showed I be budgeting for?
> 
> 
> Also there is a closet on the back wall. In that closet I have a couple shelves and I heard this can act as a poor man's diffuser and that the increased opening of the closet could help remove some reflections as is. Is this true, or am I mistaken? Would it be beneficial to just go ahead and remove those two doors? Also How should I position the wedges on the front and back wall?
> 
> 
> Thanks for listening to these basic questions.



Personally having avoided wedgies all my life, I have no idea how many you need.







My media room is of similar size...10x12x8 with a closet in the rear and a door at 45 degrees. I did super chunk bass traps in all four corners (front left and right, and inside closet left and right). I also have two 2x4 cloud absorbers, one 2x4 panel on each side wall, one 2x4 panel angled at 45 degrees along the side walls/ceiling intersection. Finally, I have four 1x4 panels behind my tv/speakers. There's a large window right behind my TV, so I couldn't fully cover that wall.


After all of these treatments, acoustics are awesome. Whenever I have someone over, they comment even with no audio how different/silent the room feels. Before the treatments the slap echo was pretty bad.


I purchased a bunch of OC703 and covered with the black and tan GOM. Wasn't exactly cheap, but works great. I'd like to do more treatment, but I'm not sure how much more I can improve things. I haven't shelled out the $$ to get some professional readings to see what could use more work.


----------



## Weasel9992




> Quote:
> Originally Posted by *Dark05* /forum/post/16251561
> 
> 
> I have a few questions, not sure if they have been answered before.
> 
> 
> I'm moving and my new media room is a 10x10x8 sheet rock walled room. It has horrible flutter echo.
> 
> 
> I have 2 questions. I don't have much to spend on acoustical treatment so is treating the first reflection point of each speaker enough to remove the flutter echo or do I need to do a completely 30-50% coverage on every wall?
> 
> 
> I'm looking at getting the Auralex wedgies that are $5 for 1 foot squares. These look rather ugly by themselves so I was also wondering if anyone had any good ideas as far as how to make these look attractive in this small room? How to place them in a pattern or Can you paint them without removing their absorbing properties?
> 
> 
> How many of these wedgies showed I be budgeting for?
> 
> 
> Also there is a closet on the back wall. In that closet I have a couple shelves and I heard this can act as a poor man's diffuser and that the increased opening of the closet could help remove some reflections as is. Is this true, or am I mistaken? Would it be beneficial to just go ahead and remove those two doors? Also How should I position the wedges on the front and back wall?
> 
> 
> Thanks for listening to these basic questions.



Oh boy...10x10x8 is a rough set of dimensions. Flutter echo is going to be the least of your concerns. I know you said you don't have a big treatment budget, but you're really going to need to treat the crap out of this place. First, you've got a set of repeating dimensions, second the room is small...that adds up to big low end problems. I wouldn't put a panel under 4" thick in a room like this...you'll need thick bass trapping on the back walls, and straddling the corners floor to ceiling if possible.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16255358
> 
> 
> Oh boy...10x10x8 is a rough set of dimensions. Flutter echo is going to be the least of your concerns. I know you said you don't have a big treatment budget, but you're really going to need to treat the crap out of this place. First, you've got a set of repeating dimensions, second the room is small...that adds up to big low end problems. I wouldn't put a panel under 4" thick in a room like this...you'll need thick bass trapping on the back walls, and straddling the corners floor to ceiling if possible.



I'm thinking "headphones" for this room.


----------



## jay131011

hey guys quick question about treating the back wall and soffit housing the projector, the rears in my 5.1 setup are energy dipoles, how do i properly treat the back wall to take advantage of the sound stage they are supposed to create? thanks!


----------



## Ph0n33z

Alrighty,


First, I just want to thank you guys ahead of time (I am presuming upon your generosity) for your advice and help. Now to the gory details....


I have a thread going for my Home Theater construction (see link ink sig). My latest post addresses the issue of where to put bass traps. I have a large corner in the front left, but absolutely no corner on the right due to a door. However, I have built a false wall (part of the proscenium) that has corners containing the L/C/R speakers (but not the sub).

False Wall Corner 


Would it be beneficial to use these corners for bass traps? If I can't do any of the corners, what about just putting up a triangle/wedge trap made out of OC 703 behind the screen where the ceiling and soffit meet?

Ceiling & Soffit 


(I didn't know if pictures were allowed in this thread, so I just included the links)


Also, I am planning on using linacoustic all around the theater side walls (but only up to 3' due to design constraints). I will then have panels with OC 703 inside at the first reflection points. Of course, I am trying to do arched panels, so figuring out how to make a frame is going to be interesting....


----------



## Dark05




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16255358
> 
> 
> Oh boy...10x10x8 is a rough set of dimensions. Flutter echo is going to be the least of your concerns. I know you said you don't have a big treatment budget, but you're really going to need to treat the crap out of this place. First, you've got a set of repeating dimensions, second the room is small...that adds up to big low end problems. I wouldn't put a panel under 4" thick in a room like this...you'll need thick bass trapping on the back walls, and straddling the corners floor to ceiling if possible.
> 
> 
> Frank



Well the back left corner is actually a 1 foot wall at a 45 degree angel so it's not a PERFECT square 


I'm looking at getting acousticmac panels. They seem like aesthetically pleasing and fairly cheap treatment.


This room is primarily only going to be seating me myself and I so do I really need to worry about flattening out the bass response across the room if I can control it for the sweet spot?


Also, With bass trapping, is it an all or nothing deal or Can I get away with hitting one or two corners?


The front Left corner is where the door is so that'll make putting a bass trap difficult.


The back left corner is that 45 degree wall. Does it need a bass trap?


The front Right is where I'm thinking about putting a single bass trap because the sub is half way along the right wall pointed towards that corner (atleast for now).


The back right is a closet, But I'm leaning more and more to removing those two doors exposing the small closet behind.


I only have a modest system and I'd rather not spend more on treatment then my speakers.


Polk rti4s, csi3, velodyne vrp-1200, onkyo 506.


Any info is greatly appreciated.


----------



## Weasel9992




> Quote:
> Originally Posted by *Dark05* /forum/post/16261706
> 
> 
> Also, With bass trapping, is it an all or nothing deal or Can I get away with hitting one or two corners?
> 
> 
> The front Left corner is where the door is so that'll make putting a bass trap difficult.
> 
> 
> The back left corner is that 45 degree wall. Does it need a bass trap?
> 
> 
> The front Right is where I'm thinking about putting a single bass trap because the sub is half way along the right wall pointed towards that corner (atleast for now).
> 
> 
> The back right is a closet, But I'm leaning more and more to removing those two doors exposing the small closet behind.
> 
> 
> I only have a modest system and I'd rather not spend more on treatment then my speakers.



It's best to treat symmetrically if you can, but if not, remember that there are more than four corners in a room. You can always hit the wall/ceiling corners as well. The front and back wall are still great candidates for bass trapping, as are the reflection points. Even in tough rooms there are almost always opportunities to absorb low end.


Frank


----------



## Dark05




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16263143
> 
> 
> It's best to treat symmetrically if you can, but if not, remember that there are more than four corners in a room. You can always hit the wall/ceiling corners as well. The front and back wall are still great candidates for bass trapping, as are the reflection points. Even in tough rooms there are almost always opportunities to absorb low end.
> 
> 
> Frank



By symmetrically do you mean front to back, or left and right?


----------



## jay131011

hey guys im kinda stressed after my carpet was put in i sat down on my riser clapped my hands and there was a wierd "ttiiiiingg" noise i have all my acoustics up behind my screen wall but not on the side or rear walls yet, any idea what that could be and how i could possible get rid of it?


----------



## Terry Montlick




> Quote:
> Originally Posted by *jay131011* /forum/post/16270730
> 
> 
> hey guys im kinda stressed after my carpet was put in i sat down on my riser clapped my hands and there was a wierd "ttiiiiingg" noise i have all my acoustics up behind my screen wall *but not on the side or rear walls yet*, any idea what that could be and how i could possible get rid of it?



That's your problem.


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *Dark05* /forum/post/16268997
> 
> 
> By symmetrically do you mean front to back, or left and right?



Well, all around really. If you can't though, then you have to look at the room and decide where your treatment opportunities are and go from there.


Frank


----------



## Weasel9992




> Quote:
> Originally Posted by *jay131011* /forum/post/16270730
> 
> 
> hey guys im kinda stressed after my carpet was put in i sat down on my riser clapped my hands and there was a wierd "ttiiiiingg" noise i have all my acoustics up behind my screen wall but not on the side or rear walls yet, any idea what that could be and how i could possible get rid of it?



Yep...Terry already said it, but you've identified your own problem!


Frank


----------



## jay131011

haha thanks guys i feel better now!


----------



## elee532

Are there any general principals for treating wall-mounted bipole surround speakers? Type of treatment? Location? Etc.? Thanks.


----------



## charcoal grey

I am going to start painting my room this weekend. And after paint I am looking to start putting up treatments. But need an opinion regarding bass traps. I was planning to make super chunk style traps from OC703 for the front and rear corners and front wall/ceiling corner also. I was recently doing more research and read that it could be more beneficial to build traps, similar to the Real Traps Mondo traps, that are 2'x4'x4, and using the extra material I would have left over to treat other corners of the room. Basically adding more square foot of coverage. Although I know my diy traps will not perform as well as the Mondo's, I am on a budget so I am trying to make the best with what I have for now.


For more info on the room, size is 11.5'x15'x8', and I will have all the first reflection points treated in addition to the bass traps.


----------



## pepar




> Quote:
> Originally Posted by *charcoal grey* /forum/post/16280547
> 
> 
> I am going to start painting my room this weekend. And after paint I am looking to start putting up treatments. But need an opinion regarding bass traps. I was planning to make super chunk style traps from OC703 for the front and rear corners and front wall/ceiling corner also. I was recently doing more research and read that it could be more beneficial to build traps, similar to the Real Traps Mondo traps, that are 2’x4’x4”, and using the extra material I would have left over to treat other corners of the room. Basically adding more square foot of coverage. Although I know my diy traps will not perform as well as the Mondo’s, I am on a budget so I am trying to make the best with what I have for now.
> 
> 
> For more info on the room, size is 11.5'x15'x8', and I will have all the first reflection points treated in addition to the bass traps.



Test data here indicates that a filled triangle outperforms one not filled. But sometimes compromises need to be made.










Don't sell DIY short. In most cases, there is no difference.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/16280649
> 
> 
> Test data here indicates that a filled triangle outperforms one not filled. But sometimes compromises need to be made.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Don't sell DIY short. In most cases, there is no difference.



+1 to all of that. If you can fill the corner then you should...and I've seen some fantastic DIY jobs. If you're careful and methodical it'll turn out great.


Frank


----------



## Scott Wallace

NEW QUESTION: In a small-ish dedicated theatre room (12'w x 18' D x 7' H), that has a fabric-covered false screenwall that is 30" from the actual wall using a 7' wide 2:35 non-perf screen, should the ENTIRE CAVITY be covered with something? In other words, you have the following areas of bare drywall unless treated....


- wall behind the screen

- sidewalls behind the screen

- ceiling behind the screen


I think most would agree that the wall behind the screen needs treatment, but what about the other two areas?


Again, keep in mind I'm not asking about first reflection sidewall or ceiling treatment as those will be outside of the screenwall and are taken care of. I am talking about whether or not in a false wall set-up you should cover all surfaces behind the screen or not, and why???


Thanks!


----------



## pepar




> Quote:
> Originally Posted by *Scott Wallace*  /forum/post/16288215
> 
> 
> NEW QUESTION: In a small-ish dedicated theatre room (12'w x 18' D x 7' H), that has a fabric-covered false screenwall that is 30" from the actual wall using a 7' wide 2:35 non-perf screen, should the ENTIRE CAVITY be covered with something? In other words, you have the following areas of bare drywall unless treated....
> 
> 
> - wall behind the screen
> 
> - sidewalls behind the screen
> 
> - ceiling behind the screen
> 
> 
> I think most would agree that the wall behind the screen needs treatment, but what about the other two areas?
> 
> 
> Again, keep in mind I'm not asking about first reflection sidewall or ceiling treatment as those will be outside of the screenwall and are taken care of. I am talking about whether or not in a false wall set-up you should cover all surfaces behind the screen or not, and why???
> 
> 
> Thanks!



The advice when I built mine 4-5 years ago for a micro-perfed Stewart screen was to line the entire cavity with 2" of 'glass. The reason as I understood it was to reduce/eliminate comb filtering from the sound bouncing around behind the screen. I imagine that the same thinking would apply today?


----------



## Scott Wallace




> Quote:
> Originally Posted by *pepar* /forum/post/16288297
> 
> 
> The advice when I built mine 4-5 years ago for a micro-perfed Stewart screen was to line the entire cavity with 2" of 'glass. The reason as I understood it was to reduce/eliminate comb filtering from the sound bouncing around behind the screen. I imagine that the same thinking would apply today?



That is what I would think, and how I often see them built. I was told that I only needed to worry about reflections that occurred around my ears and that meant I didn't need to worry about the sliver of sidewall and ceiling behind the screenwall that were untreated. Of course, unless you do something you can't be sure if it is going to be better.


Thanks for the advice.


Anyone else with experience in this area?


----------



## pepar




> Quote:
> Originally Posted by *Scott Wallace* /forum/post/16288967
> 
> 
> That is what I would think, and how I often see them built. I was told that I only needed to worry about reflections that occurred around my ears and that meant I didn't need to worry about the sliver of sidewall and ceiling behind the screenwall that were untreated. Of course, unless you do something you can't be sure if it is going to be better.



My concern is that any sound coming out of that area that is not direct can only blur the direct sound.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/16288297
> 
> 
> The advice when I built mine 4-5 years ago for a micro-perfed Stewart screen was to line the entire cavity with 2" of 'glass. The reason as I understood it was to reduce/eliminate comb filtering from the sound bouncing around behind the screen. I imagine that the same thinking would apply today?



When I did mine just a few months ago, Terry Montlick gave me the same advise. I had only one inch up and the second layer of 1" linacoustic made a big difference. I asked about going with 3 inches since I have plenty of extra but never got a reply. I took that to mean that two was enough.


My scr5een is not micro-perfed.


----------



## Lonely Raven

OK, I have an odd question here.


My fiancé and I are bouncing design (as in aesthetic design) ideas off each other on how we want to put some sound absorption on the ceiling at first reflection points. Patterns, shapes, wood frame exposed or hidden, all that sort of thing.


So I have this great idea that I believe will work both aesthetically as well as sonically, but it involves one of two options because 5 sides of the ridged insulation will be visible:


#1, either I buy a ton of cloth and completely wrap each piece before mounting (super expensive! and very labor intensive)


#2, a light spray of paint to turn the yellow insulation a reasonable shade of black on all sides.


Now, I know having the insulation exposed isn't a good thing, but it's going to be on the ceiling, it's not going to be moved or rustled, and I feel the spray paint will help contain the fibers.


Which brings me back to the original question...would spraying on a couple thin layers of a quality spray paint destroy the insulations acoustic properties? I've been day-dreaming about it for a couple hours, and I honestly think not.


Thoughts?


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/16290163
> 
> 
> When I did mine just a few months ago, Terry Montlick gave me the same advise. I had only one inch up and the second layer of 1" linacoustic made a big difference. I asked about going with 3 inches since I have plenty of extra but never got a reply. I took that to mean that two was enough.
> 
> 
> My scr5een is not micro-perfed.



I've seen some recommend thicker to "reach" lower, but bass traps are needed anyway and in my room it's all worked out nicely.


----------



## pepar




> Quote:
> Originally Posted by *Lonely Raven* /forum/post/0
> 
> 
> 
> Thoughts?


 Frames ? Otherwise, how were you planning on fastening then in place?


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16290748
> 
> 
> I've seen some recommend thicker to "reach" lower, but bass traps are needed anyway and in my room it's all worked out nicely.



Right. In my case, I can actually get 4" on my front wall, but I don't have the room to put bass traps in the front of the room (I know I've mentioned this before, but alas). So I'm going to put 4" of 703 on my entire front wall, except the door. I'm going to hang 2" on my door with a 1" gap behind it, because that's all I can fit in that corner.


Then I'll do the normal early reflection points, a good portion of the back wall, and the rear wall-to-wall corners as bass traps. I don't have enough head room to do the wall-to-ceiling corners...


Hopefully, it'll be a significant improvement over what I Have now.



Actually, that leads to my next question. I bought a lap top - an HP pavillion running Vista home x64. I want to take measurements in my room so I have a better idea of what I'm working with and how my treatments will change the room.


I'm thinking that I can use this: http://www.hometheatershack.com/roomeq/ 


But, what should I get for a microphone? Any suggestions?


----------



## Terry Montlick




> Quote:
> Originally Posted by *will1383* /forum/post/16293325
> 
> 
> But, what should I get for a microphone? Any suggestions?



Behringer ECM8000 Measurement Microphone.

At $50, it is a winner in price vs. performance. You will need a phantom power preamp to go with it, but this is true of most microphones these days.


- Terry


----------



## will1383




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16293371
> 
> 
> Behringer ECM8000 Measurement Microphone.
> 
> At $50, it is a winner in price vs. performance. You will need a phantom power preamp to go with it, but this is true of most microphones these days.
> 
> 
> - Terry



Phantom power preamp? I'm assuming I can just google these and find what I need.


----------



## will1383

A couple more questions regarding corner bass traps:


Is it better to completely fill the corner with material (in this case, OC703) or to leave a gap between the corner and the material?


Is there any rule of thumb to determine how deep the traps should be and/or how wide they should be? At the moment, I was thinking of simply cutting the OC703 sheets into 24" squares, then cutting them in half forming a triangle, then placing that triangle into the corner. That would make for a 24" wide face, and a trap that is roughly 17" deep. Is this going to be satisfactory? Is there a way to calculate what is really needed?


Thanks in advance.


----------



## unclepauly




> Quote:
> Originally Posted by *will1383* /forum/post/16293900
> 
> 
> A couple more questions regarding corner bass traps:
> 
> 
> Is it better to completely fill the corner with material (in this case, OC703) or to leave a gap between the corner and the material?
> 
> 
> Is there any rule of thumb to determine how deep the traps should be and/or how wide they should be? At the moment, I was thinking of simply cutting the OC703 sheets into 24" squares, then cutting them in half forming a triangle, then placing that triangle into the corner. That would make for a 24" wide face, and a trap that is roughly 17" deep. Is this going to be satisfactory? Is there a way to calculate what is really needed?
> 
> 
> Thanks in advance.



The only thing I can think of that would be better than that barring any specialty setup would be to use OC705.


----------



## cuzed2

Not a pure acoustics question, but related:


The areas immediatly to the sides of my screen will be flanked with floor to ceiling drapes. The drywall directly behind these drapes will be covered with JM Linacoustic.


Does anyone feel it necessary to cover the linacoustic with GOM before hanging the drapes. The wall behind the drapes will never be seen, nor disturbed.


Just wondering if covering the Linacoustic is recommended to keep the insulation "dust or fibers" contained, or perhaps this is necessary for code concerns?


Thanks in Advance!


----------



## Ph0n33z




> Quote:
> Originally Posted by *Ph0n33z* /forum/post/16259835
> 
> 
> Alrighty,
> 
> 
> NEW QUESTION:
> 
> 
> I have a thread going for my Home Theater construction (see link ink sig). My latest post addresses the issue of where to put bass traps. I have a large corner in the front left, but absolutely no corner on the right due to a door. However, I have built a false wall (part of the proscenium) that has corners containing the L/C/R speakers (but not the sub).
> 
> False Wall Corner
> 
> 
> Would it be beneficial to use these corners for bass traps? If I can't do any of the corners, what about just putting up a triangle/wedge trap made out of OC 703 behind the screen where the ceiling and soffit meet?
> 
> Ceiling & Soffit
> 
> 
> (I didn't know if pictures were allowed in this thread, so I just included the links)
> 
> 
> Also, I am planning on using linacoustic on the entire front wall and all around the theater side walls (but only up to 3' due to design constraints). I will then have panels with OC 703 inside at the first reflection points. Of course, I am trying to do arched panels, so figuring out how to make a frame is going to be interesting....



BUMP.........seems I got lost in the madness!


----------



## pepar




> Quote:
> Originally Posted by *Ph0n33z* /forum/post/16306488
> 
> 
> BUMP.........seems I got lost in the madness!










It can't hurt.


----------



## elee532




> Quote:
> Originally Posted by *elee532* /forum/post/16277727
> 
> 
> Are there any general principals for treating wall-mounted bipole surround speakers? Type of treatment? Location? Etc.? Thanks.



Anyone?


----------



## pepar




> Quote:
> Originally Posted by *elee532* /forum/post/16307764
> 
> 
> Anyone?



I would not place any acoustical treatments near a dipole or bipole surround speaker.


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16307907
> 
> 
> I would not place any acoustical treatments near a dipole or bipole surround speaker.



What's considered 'near' ? I have both.


Well, actually, that's a decent question:


How do you determine whether or not to use dipole or bipole on the sides and/or rear? Or maybe that question is outside the scope of this thread.


----------



## elee532




> Quote:
> Originally Posted by *will1383* /forum/post/16308533
> 
> 
> What's considered 'near' ?



Yeah, I would like to know this as well. There is a corner bass trap thats about 2 or 3 feet from one of my surrounds. Of course, maybe it's irrelevant sine I can't move either of them.


----------



## Dennis Erskine

Dipole/Bipoles can benefit from diffusion from the speaker to about 2'.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16309483
> 
> 
> Dipole/Bipoles can benefit from diffusion from the speaker to about 2'.



Yes, I thought about adding the word "absorption" to my post, but neglected to do so.


----------



## cuzed2

Bump;


Anyone have an opinion on NOT covering linacoustic...?


----------



## pepar

I am about to add more SSC bass traps to my room that are not behind the false wall and need to be covered. I have black GOM, but would like to cover them with a color that matches my walls. Are there any commercialy available fabrics that should NOT be used to cover this style bass traps?


----------



## Scott Wallace




> Quote:
> Originally Posted by *pepar* /forum/post/16307907
> 
> 
> I would not place any acoustical treatments near a dipole or bipole surround speaker.



Actually, these can benefit quite a bit from adding diffusion to areas in the line of sight of where the drivers are directed. That way, you're taking an already effective design in terms of using the room to good advantage even better by taking what otherwise would be a series of direct reflections and spreading those out even more evenly. Diffusion where the sound of the driver would otherwise hit a bare wall. A good question!


----------



## pepar




> Quote:
> Originally Posted by *Scott Wallace* /forum/post/16311186
> 
> 
> Actually, these can benefit quite a bit from adding diffusion to areas in the line of sight of where the drivers are directed. That way, you're taking an already effective design in terms of using the room to good advantage even better by taking what otherwise would be a series of direct reflections and spreading those out even more evenly. Diffusion where the sound of the driver would otherwise hit a bare wall. A good question!



I think the context was "around" these speakers.


To your point, though, I have a totally dead front end and have considered placing skylines so that the front lobe of the side surround dipoles doesn't die immediately like it does now.


----------



## Weasel9992




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16309483
> 
> 
> Dipole/Bipoles can benefit from diffusion from the speaker to about 2'.



+2. We commonly recommend that for dipoles...depends on the rest of the room context though.


Frank


----------



## cuzed2




> Quote:
> Originally Posted by *cuzed2* /forum/post/16304597
> 
> 
> Not a pure acoustics question, but related:
> 
> 
> The areas immediatly to the sides of my screen will be flanked with floor to ceiling drapes. The drywall directly behind these drapes will be covered with JM Linacoustic.
> 
> 
> Does anyone feel it necessary to cover the linacoustic with GOM before hanging the drapes. The wall behind the drapes will never be seen, nor disturbed.
> 
> 
> Just wondering if covering the Linacoustic is recommended to keep the insulation "dust or fibers" contained, or perhaps this is necessary for code concerns?
> 
> 
> Thanks in Advance!



Does anyone feel strongly either way;


1) covering linacoustic in GOM

or

2) is covering with a curtain not advised


Thanks!


----------



## Dennis Erskine

Covering linacoustic ...


Here is the generic answer to all fiberglass based board products:


Certain manufactured board products (including duct liner and Coated Insul-Shield Black) have been approved for installation in free air spaces. In other words, when installed according to the manufacturer's instructions, these fiberglass products will not "shed" fibers into the air and are allowed to be installed in rooms without additional protective coverings.


If the product is not so certified (review the MSDS for the product), then that product must be covered with another barrier (such as GOM).


----------



## cuzed2

Thanks Dennis - appreciate it !!


----------



## notoriousmatty

Gonna start my first GIK panel trial and error. I have a 11 wide by 17 long 7 foot high ceiling room. The speakers , sub, and 60 inch tv are on the 11wide wall space. Im sitting about 10 feet back from the front. Im using 100 percent HT klipsch speakers. What do you think I should use. Absorb as much as the wall behind the speakers as possible? Diffusors or absorbers along the side walls? I have bipoles and Ive been told not to put absorbers close to them. Since im 7 feet from the back wall do I need to put any treatments back there? It seems like a pretty basic setup and I read as much literature as I can but it seems to get blurred on opinion/fact. Thanks.


----------



## Weasel9992




> Quote:
> Originally Posted by *notoriousmatty* /forum/post/16343205
> 
> 
> Gonna start my first GIK panel trial and error. I have a 11 wide by 17 long 7 foot high ceiling room. The speakers , sub, and 60 inch tv are on the 11wide wall space. Im sitting about 10 feet back from the front. Im using 100 percent HT klipsch speakers. What do you think I should use. Absorb as much as the wall behind the speakers as possible? Diffusors or absorbers along the side walls? I have bipoles and Ive been told not to put absorbers close to them. Since im 7 feet from the back wall do I need to put any treatments back there? It seems like a pretty basic setup and I read as much literature as I can but it seems to get blurred on opinion/fact. Thanks.



Bass trapping on the back wall...look into the possibility of diffusion for the front wall. The rear corners can be used for bass trapping as well...*possibly* the front corners depending on how far apart the speakers are.


Frank


----------



## charcoal grey

Ok, I have the bass traps under control but have a question on the broadband (first reflection point) panels. I am going to use 2" OC703 spaced 2" from the wall. But I was actually going to build spacers that I will attach to the wall, and mount the OC703 to that, then cover that with poly batting. This way the panels are usable while I construct my frames and paint them, then I will mount them over the panels already secured to the wall. Only thing is poly batting seems to only come in white. And since I am making 18+ 2'x2' panels, it will probably take several months to actually complete all of them. Can I paint or dye the batting black? I would like to have the room usable while I am working on the cosmetic frames. And having all that white on the walls is not ideal.


Mark


----------



## Terry Montlick

Poly batting isn't really a finishing material. It doesn't look great exposed. Use acoustically transparent fabric instead.


- Terry


----------



## Weasel9992

Hey Mark...I agree with Terry that it's not a good finishing material, but if you're just putting up temporarily while you finish the frames for the panels, then that's fine. It won't look great, but as long as you can live with it I don't see any harm.


Frank


----------



## velvet396

put curtains up in the living room. What a difference!! (visually)










The wife came back with a much thinner fabric than I was expecting. Oh well, it's our hangout space, not our acoustic perfection space.









I'll get that area going when we buy a house.


----------



## charcoal grey

What I meant was that I am building finish grames with black GOM in the center. This will cover the panels that I am attaching to the walls. I have seen several builds where people use batting between the OC703 and the GOM. I just did not want a bunch of white panels on the walls (for temporary) while I am making my finial frames with GOM inserts. I would not want to watch movies with all the unfinished panels on the walls if left white. Just wondered if painting the batting black would cause a problem with sound? Or is batting really needed? That would cut down on cost also if I eliminated the batting.


Mark


----------



## Weasel9992




> Quote:
> Originally Posted by *charcoal grey* /forum/post/16353141
> 
> 
> Or is batting really needed? That would cut down on cost also if I eliminated the batting.



It really isn't needed. Fabric right over the 703 is just fine.


Frank


----------



## weverb

Good People,


Excuse the nooby question, but is it better to treat the tri-corners (wall-wall-ceiling or wall-wall-floor) or the corners created by two walls with bass traps first?


I went through my room and measured the spl at the different corners in my room. I started with a reference of 75dB at my "sweet spot" and then started measuring with a Rat Shack meter the different corners. I found my wall-wall-ceiling readings to be consistent at about 80dB, my wall-wall corners to be 78-79dB, and my wall-wall-floor readings to be about 83dB. I have pictures available if that would help.


Thanks.


----------



## Terry Montlick




> Quote:
> Originally Posted by *weverb* /forum/post/16358059
> 
> 
> Good People,
> 
> 
> Excuse the nooby question, but is it better to treat the tri-corners (wall-wall-ceiling or wall-wall-floor) or the corners created by two walls with bass traps first?



If you have an untreated room, it is better to get your room reverberation under control with wideband acoustic panels first. Then you can worry about bass traps.


There is more area to effectively treat if you deal with the four 2-corner wall intersections. Going floor to ceiling with a nice deep corner absorber can be very effective. Unfortunately, the sound level measurements you made in the corners don't yield any useful information.










Regards,

Terry


----------



## weverb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16359040
> 
> 
> If you have an untreated room, it is better to get your room reverberation under control with wideband acoustic panels first. Then you can worry about bass traps.
> 
> 
> There is more area to effectively treat if you deal with the four 2-corner wall intersections. Going floor to ceiling with a nice deep corner absorber can be very effective. Unfortunately, the sound level measurements you made in the corners don't yield any useful information.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards,
> 
> Terry



Thanks Terry.


I have a few diy panels that I have placed behind my mains, center, and on the back wall directly behind the listening position.


So could I assume from you comment, that it is better to treat surface area rather than where the spl peaks are? What else could I provide that would be more helpful? Pictures, layout, etc.?


----------



## Weasel9992




> Quote:
> Originally Posted by *weverb* /forum/post/16359299
> 
> 
> What else could I provide that would be more helpful? Pictures, layout, etc.?



Both would be great!


Frank


----------



## Terry Montlick




> Quote:
> Originally Posted by *weverb* /forum/post/16359299
> 
> 
> Thanks Terry.
> 
> 
> I have a few diy panels that I have placed behind my mains, center, and on the back wall directly behind the listening position.
> 
> 
> So could I assume from you comment, that it is better to treat surface area rather than where the spl peaks are?



Yes. The spl peaks will be high in corners and at surfaces. That is where pressures must be high. But you can't really tell anything from the single numbers you read on a meter. Even pressure as a function of frequency is of little use in determining treatment spots.


> Quote:
> What else could I provide that would be more helpful? Pictures, layout, etc.?



Yes.


----------



## weverb




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16359465
> 
> 
> Both would be great!
> 
> 
> Frank



As requested by Terry and Frank:


----------



## Terry Montlick

With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways.







Like the Energizer Bunny, it keeps on going! Especially low frequency sound. This means that subwoofer frequencies can easily escape into larger spaces, and may not be an issue. Higher frequencies, on the other hand, are more readily trapped between parallel walls, and may create problems.


- Terry


----------



## weverb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16359858
> 
> 
> With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways.
> 
> 
> 
> 
> 
> 
> 
> Like the Energizer Bunny, it keeps on going! Especially low frequency sound. This means that subwoofer frequencies can easily escape into larger spaces, and may not be an issue. Higher frequencies, on the other hand, are more readily trapped between parallel walls, and may create problems.
> 
> 
> - Terry



So what are your recommendations? There are very few reflection points left. Ceiling, above the entertainment center, above the picture, etc.?


----------



## Terry Montlick




> Quote:
> Originally Posted by *weverb* /forum/post/16359890
> 
> 
> So what are your recommendations? There are very few reflection points left. Ceiling, above the entertainment center, above the picture, etc.?



Yes. I see lots of lovely open wall space (which your wife may not). Absorbers don't need to be restricted to first reflection points.


----------



## notoriousmatty

Is it better to use absorbers that are effective down below 80hz on the front wall or absorbers that are effective down to 250hz? GIK 242 vs GIK 244 for front wall deadening?


----------



## notoriousmatty

No one seems to visit this board anymore. I ordered gik tri traps and 3 242 panels for first reflection points and behind the center channel. The trip traps cover alot of the 3 feet of space I have from the side of the tv to the wall. Well see how it goes.


----------



## Weasel9992




> Quote:
> Originally Posted by *notoriousmatty* /forum/post/16360841
> 
> 
> Is it better to use absorbers that are effective down below 80hz on the front wall or absorbers that are effective down to 250hz? GIK 242 vs GIK 244 for front wall deadening?



Either one would be fine, honestly...depends on the issues you're having. If it's a small room, then the 244 is probably the right choice because it's a broad band panel. Then again, you might not have the space in a smaller room for a 4" panel on the front wall and reflection points. It depends totally on the room.


Frank


----------



## techtvman

I have a null at 70hz in the vertical plane and it just so happens to be at the same height my head is when sitting on my couch, what kinds of acoustical treatments would help me out?


----------



## pepar




> Quote:
> Originally Posted by *techtvman* /forum/post/16379049
> 
> 
> I have a null at 70hz in the vertical plane and it just so happens to be at the same height my head is when sitting on my couch, what kinds of acoustical treatments would help me out?



34" face SSC Bass traps . Or something tuned to your null.


----------



## Ph0n33z

So you guys don't know what I can do with my situation? I posted twice, but apparently I smell or something....


----------



## Terry Montlick




> Quote:
> Originally Posted by *techtvman* /forum/post/16379049
> 
> 
> I have a null at 70hz in the vertical plane and it just so happens to be at the same height my head is when sitting on my couch, what kinds of acoustical treatments would help me out?



Treatments for vertical modes this low in frequency are largely ineffective. Just raise your subwoofer on a large, heavy box so it is closer to ear level. Assuming it is such a vertical mode (you'd get one with an 8' ceiling), the null should disappear.


- Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ph0n33z* /forum/post/16259835
> 
> 
> Alrighty,
> 
> 
> First, I just want to thank you guys ahead of time (I am presuming upon your generosity) for your advice and help. Now to the gory details....
> 
> 
> I have a thread going for my Home Theater construction (see link ink sig). My latest post addresses the issue of where to put bass traps. I have a large corner in the front left, but absolutely no corner on the right due to a door. However, I have built a false wall (part of the proscenium) that has corners containing the L/C/R speakers (but not the sub).
> 
> False Wall Corner
> 
> 
> Would it be beneficial to use these corners for bass traps?



In general, yes.


> Quote:
> If I can't do any of the corners, what about just putting up a triangle/wedge trap made out of OC 703 behind the screen where the ceiling and soffit meet?



Not nearly as good a solution. Room corners are superior.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16379332
> 
> 
> Treatments for vertical modes this low in frequency are largely ineffective.- Terry



Even a chunk-style trap installed at a wall/ceiling juncture?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16379487
> 
> 
> Even a chunk-style trap installed at a wall/ceiling juncture?



You'd have to put these all the way around the perimeter of the room to have a significant effect.


----------



## Ph0n33z




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16379430
> 
> 
> In general, yes.
> 
> 
> Not nearly as good a solution. Room corners are superior.
> 
> 
> - Terry



Thank you for replying!


Would you recommend doing just one of the front room corners (which is where the subwoofer will be located) without being able to do the other? And then doing the false wall corners as well?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ph0n33z* /forum/post/16394961
> 
> 
> Thank you for replying!
> 
> 
> Would you recommend doing just one of the front room corners (which is where the subwoofer will be located) without being able to do the other? And then doing the false wall corners as well?



Low frequency room mode treatment is equally effective in all corner(s). No advantage to having it in the same corner as the sub.


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16379702
> 
> 
> You'd have to put these all the way around the perimeter of the room to have a significant effect.



Definitely the more square footage you cover, the better.


Frank


----------



## funlvr1965

Im doing a makeover in my existing theater, room is approx 13 x 17 currently with mid/high frequency absorbers on the wall at first reflection points. I want to cover the wall with wallfabric which with the installation tracks that mount to the wall will put the fabric 1 inch off the wall so I figured I could get rid of my absorbers and just do like everyone seems to be doing that do fabric walls which is to put 1" lincoustic up to ear height around the room then cover with wallfabric in front of that. I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?. At this point I guess what I will do is still mount my walltraps on the wall but place the framing tracks for the GOM fabric around them so I can have the best of both worlds. The only thing I dont know is should I still place 1" lincoustic on the wall behind the wallfabric. If I dont get this right it could be a costly mistake. If anyone wants to see pics of my room there are some in my signature from the article that appeared in the electronic house magazine in print and online. Any suggestions would be helpful at this point.


----------



## Mark Seaton




> Quote:
> Originally Posted by *funlvr1965* /forum/post/16404913
> 
> 
> I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?.



I'll second that engineer's recommendation. I see many doing it, and every room I've been in has faced similar issues. I'm still a fan of wider bandwidth devices (usually thicker) in select locations and leaving enough reflective area elsewhere to keep the room from sounding too dead or over damped above 1-2kHz.


----------



## will1383

Bear in mind that we, as humans live in a highly reflective world. So our hearing has adapted to a reflective environment. Because of this, in many cases a 'dead' room actually sounds less appealing to us because we are accustomed to hearing things in a live environment.


So the key is not to make the room totally dead, but to address the focal points of where you are hearing the sound source.


----------



## pepar

Better yet, get some free software and a calibrated mic and take some measurements. Alternatively, one can listen to different conflicting opinions and make a decision w/o any data on the space in question.


----------



## will1383

Yup. I still have to get a microphone. Trying to find a decent preamp for it.


----------



## Weasel9992




> Quote:
> Originally Posted by *will1383* /forum/post/16405285
> 
> 
> Yup. I still have to get a microphone. Trying to find a decent preamp for it.



I'm a mix engineer by trade, and I'd tell you to just get an EMC8000 (Behringer) and an M-Audio DMP3. You'll spend about $150 on both, and they'll work great for measurement purposes.


Frank


----------



## CJO




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16405471
> 
> 
> I'm a mix engineer by trade, and I'd tell you to just get an EMC8000 (Behringer) and an M-Audio DMP3. You'll spend about $150 on both, and they'll work great for measurement purposes.
> 
> 
> Frank



I can find the ECM8000 for pretty cheap ($50 +/-), but where can you find the M-Audio DMP3 for less than $150?


Thanks,

CJ


----------



## nathan_h




> Quote:
> Originally Posted by *funlvr1965* /forum/post/16404913
> 
> 
> I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?



Nice theater. Cool slide show.


The simple answer to your question is: mostly. If you have covered the first reflection points, covering more of the walls at random (or "up to ear level all around") with high frequency absorption is likely to have a negative impact on the quality of the sound in the room.


In fact, looking at your room, I'd say you've got several first reflection points covered -- GOOD. Cover them all and you'll be half way there.


The other half? Bass trapping. Unless there is something hiding somewhere, it looks like you need bass trapping. Which means thick bulky stuff in the corners. Lots of good DIY examples around here, and many good commercial options, as well.


Measurements would be cool, and tell you even more, but there are few rooms that cannot benefit from more bass trapping, so that's a safe suggestion and probably your biggest bang-for-buck improvement option.


----------



## funlvr1965




> Quote:
> Originally Posted by *nathan_h* /forum/post/16405865
> 
> 
> Nice theater. Cool slide show.
> 
> 
> The simple answer to your question is: mostly. If you have covered the first reflection points, covering more of the walls at random (or "up to ear level all around") with high frequency absorption is likely to have a negative impact on the quality of the sound in the room.
> 
> 
> In fact, looking at your room, I'd say you've got several first reflection points covered -- GOOD. Cover them all and you'll be half way there.
> 
> 
> The other half? Bass trapping. Unless there is something hiding somewhere, it looks like you need bass trapping. Which means thick bulky stuff in the corners. Lots of good DIY examples around here, and many good commercial options, as well.
> 
> 
> Measurements would be cool, and tell you even more, but there are few rooms that cannot benefit from more bass trapping, so that's a safe suggestion and probably your biggest bang-for-buck improvement option.



Thanks Nathan, it doesn't look quite so cool now since its in a state of renovation, well it seems like based on my calculations from various seats regarding my reflection points I will end up with a 48" trap on either side of the wall and will forgo any lincoustic material and add about 4" or more of trapping on the front wall below the screen and in back of the front speakers. Thanks for everyone who added a little something to the mix and also thanks to Mark Seaton who picked up the phone and gave me some good advice. I invested in him early on (catalysts,submersives..etc) and its paying off


----------



## Weasel9992




> Quote:
> Originally Posted by *CJO* /forum/post/16405555
> 
> 
> I can find the ECM8000 for pretty cheap ($50 +/-), but where can you find the M-Audio DMP3 for less than $150?
> 
> 
> Thanks,
> 
> CJ



I've seen it on Ebay and on the net for $99.99 from time to time.


Frank


----------



## pepar

There are five or six on ebay Buy It Now at $159, but with the Best Offer option. And there is a regular auction at $61 and four days to go. And one at $12 with five days to go.


----------



## cavchameleon

Sweetwater has the M-Audio DMP3 for 159.99 with free shipping.

http://www.sweetwater.com/store/detail/DMP3 


Here is another option: Tascam US-144 which is 149.99 with free shipping (I'm using this unit and it works very well).

http://www.sweetwater.com/store/detail/US144/


----------



## Ethan Winer




> Quote:
> Originally Posted by *funlvr1965* /forum/post/16404913
> 
> 
> I consulted with a respectable acoustic engineer this morning and he said that I SHOULD NOT use 1" lincoustic around the room as it would be too dead sounding, so everyone who is doing lincoustic around the lower half to ear level is wrong?



Mark Seaton gave you the right answer too. As I explained on the phone, there are three problems with what you propose:


1) Rigid fiberglass only one inch thick does not absorb to a low enough frequency. I suggest two inches thick as a minimum. Otherwise all you'll absorb is treble and a little midrange. If your fabric track is only one inch deep, attach it to firring strips to bring it our farther and make a deeper cavity to accommodate two-inch fiberglass (or two layers of one inch).


2) Absorbing the lower half of a wall up to ear level kinda misses the mark. It covers the very bottom of the wall where absorption is not needed, and leaves the part just above your ears reflective. Sound leaves loudspeakers in an arc, spreading upward, downward, and outward the farther it goes. So absorption should extend to at least a foot above ear level on the side walls.


3) Covering a 4-foot high swath around the room centered at ear level is fine, but covering all of the walls from floor to ceiling is definitely too much absorption. Even a band going all around the room is probably too much since what really matters are the reflection points.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *cavchameleon* /forum/post/16409813
> 
> 
> Sweetwater has the M-Audio DMP3 for 159.99 with free shipping.
> 
> http://www.sweetwater.com/store/detail/DMP3
> 
> 
> Here is another option: Tascam US-144 which is 149.99 with free shipping (I'm using this unit and it works very well).
> 
> http://www.sweetwater.com/store/detail/US144/



I would follow the two auctions and bid in the last five seconds if the price hasn't gotten bid too high before coughing up $160 . . .


----------



## CJO




> Quote:
> Originally Posted by *pepar* /forum/post/16409906
> 
> 
> I would follow the two auctions and bid in the last five seconds if the price hasn't gotten bid too high before coughing up $160 . . .



That would be my preference too. However, I have a while before I need one and I think that Will should have first dibs.


CJ


----------



## cavchameleon




> Quote:
> Originally Posted by *pepar* /forum/post/16409906
> 
> 
> I would follow the two auctions and bid in the last five seconds if the price hasn't gotten bid too high before coughing up $160 . . .



Agreed! I'd do the same.


----------



## funlvr1965




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16409900
> 
> 
> Mark Seaton gave you the right answer too. As I explained on the phone, there are three problems with what you propose:
> 
> 
> 1) Rigid fiberglass only one inch thick does not absorb to a low enough frequency. I suggest two inches thick as a minimum. Otherwise all you'll absorb is treble and a little midrange. If your fabric track is only one inch deep, attach it to firring strips to bring it our farther and make a deeper cavity to accommodate two-inch fiberglass (or two layers of one inch).
> 
> 
> 2) Absorbing the lower half of a wall up to ear level kinda misses the mark. It covers the very bottom of the wall where absorption is not needed, and leaves the part just above your ears reflective. Sound leaves loudspeakers in an arc, spreading upward, downward, and outward the farther it goes. So absorption should extend to at least a foot above ear level on the side walls.
> 
> 
> 3) Covering a 4-foot high swath around the room centered at ear level is fine, but covering all of the walls from floor to ceiling is definitely too much absorption. Even a band going all around the room is probably too much since what really matters are the reflection points.
> 
> 
> --Ethan




Ethan thanks for the reply, heres my game plan as per speaking with you and Mark on the phone last night. I plan on mounting 1" furring strips(top and bottom) horizontally across the wall then add my 1" track around the perimiter of the wall to attach the wall fabric, the fabric is going over the furring strips. I then I will reattach my wall 2" panels to the furring strips on the wall which when attached will have a 1" gap between the wall and the back the panel. In looking at reflection points from ALL my seats is seems that I am in need of two panels measuring 4x4 which is to say 2 2x4 panels right next to each other,same on the other wall, and a panel right on the door which will be a reflection point next to my right speaker. Mark then suggested that with the room I have underneath the screen (about 22"_ high x 8" deep) between the back of the speakers and the front wall that I put 4" or possibly more of fiberglass or rockwool on that wall so thats what I plan on doing. As far as bass traps, all total there will be a total of 7 and thats squeezing in one more trap on the ceiling above the seating area where the ceiling meets a soffited area, currently there is one there and I will add another 4 inch panel. The room will be chock full of panels. Thanks for the help now its time to get to work.


----------



## cuzed2

To All,


Thanks for discussing this topic; "too-much-sidewall" treatments - you have all just helped me make a decision NOT to cover my entire sidewall areas with Linacoustic. For sidewalls I will treat only the sidewall reflection points.


I will now concentrate on the screen-wall and seeing if I can go beyond 3 corner traps.

My corner traps are all up front; 2 vertical corners, and one across the top (wall to ceiling interface). I now need to find a way to get more bass trapping into the rear of my room.


FWIW: Mark/Wayne >> met you both at Zamboniman's first meet, was traveling when the 2nd one occured. Hope all is well for you guys!!


----------



## pepar




> Quote:
> Originally Posted by *cuzed2* /forum/post/16415544
> 
> 
> To All,
> 
> 
> Thanks for discussing this topic; "too-much-sidewall" treatments - you have all just helped me make a decision NOT to cover my entire sidewall areas with Linacoustic. For sidewalls I will treat only the sidewall reflection points.
> 
> 
> I will now concentrate on the screen-wall and seeing if I can go beyond 3 corner traps.
> 
> My corner traps are all up front; 2 vertical corners, and one across the top (wall to ceiling interface). I now need to find a way to get more bass trapping into the rear of my room.



That is exactly where I am right now. My "three corner" front traps are behind my false wall, so I did not have to be concerned that much with appearance. The ones I add in the rear of the room will be visible and will need to be covered to avoid being a sore thumb.


----------



## will1383




> Quote:
> Originally Posted by *pepar* /forum/post/16415603
> 
> 
> That is exactly where I am right now. My "three corner" front traps are behind my false wall, so I did not have to be concerned that much with appearance. The ones I add in the rear of the room will be visible and will need to be covered to avoid being a sore thumb.



Yup. I know what I'm going to do, but I have to get my molding and trim up before I can do it.


----------



## LHD21

It took me a couple of weeks but I think I've made it through this whole thread. Now I may have missed it but what other solutions besides REW are available to take acoustic measurements; and of those, which do the pros use?


I see the DEQ has RTA built in measurement but it looks limited to the tiny LCD.


----------



## Ethan Winer

I'm a pro and I use REW. Hey, it's fabulous and it's free. Why even look further?


--Ethan


----------



## rutlian




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16409900
> 
> 
> Mark Seaton gave you the right answer too. As I explained on the phone, there are three problems with what you propose:
> 
> 
> 1) Rigid fiberglass only one inch thick does not absorb to a low enough frequency. I suggest two inches thick as a minimum. Otherwise all you'll absorb is treble and a little midrange. If your fabric track is only one inch deep, attach it to firring strips to bring it our farther and make a deeper cavity to accommodate two-inch fiberglass (or two layers of one inch).
> 
> 
> 2) Absorbing the lower half of a wall up to ear level kinda misses the mark. It covers the very bottom of the wall where absorption is not needed, and leaves the part just above your ears reflective. Sound leaves loudspeakers in an arc, spreading upward, downward, and outward the farther it goes. So absorption should extend to at least a foot above ear level on the side walls.
> 
> 
> 3) Covering a 4-foot high swath around the room centered at ear level is fine, but covering all of the walls from floor to ceiling is definitely too much absorption. Even a band going all around the room is probably too much since what really matters are the reflection points.
> 
> 
> --Ethan



Hi Ethan I tooked advantage of your comments above, I have a small room and I have some rigid fiberglass 24x48x2 horizontally below ear levels in my sidewalls and I remove them and scattered them 1 foot above ear levels or just about and I am glad I did because I am happy with the results. I removed every rigid fiberglass I have below ear levels except at the front wall.


And thank you for always sharing...


----------



## LHD21




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16424451
> 
> 
> I'm a pro and I use REW. Hey, it's fabulous and it's free. Why even look further?
> 
> 
> --Ethan



I'm very well aware of the unintended consequences that come with application level systems. As little as a java update could skew things or prevent it from working completely. I prefer appliance level reliability and longevity of service.


Of course there's always the line of thinking that you simply don't perform any software upgrades but what happens when you have a drive failure and some facet of your application isn't available anylonger?



Its probably not an issue but old habits die hard.


----------



## Weasel9992




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16424451
> 
> 
> I'm a pro and I use REW. Hey, it's fabulous and it's free. Why even look further?



Me too. I've never had a problem.


Frank


----------



## Terry Montlick

REW is not just any old Java program. John Mulcahy, its author, is one seriously smart guy with a lot of experience in signal processing.


- Terry


----------



## cuzed2

Hope I am not breaking any forum rules with the following. I meant to note this experience last week:

*A big call-out to GIK for outstanding service* (and in this day and age - even average service is hard to find)


Two weeks ago;

- late on a Tuesday afternoon; I ordered some GOM

- To my surprise I had the GOM on my Illinois doorstep on Thursday


Just wanted to share an Excellent experience with GIK (and A Thanks to Frank as well)!


----------



## will1383




> Quote:
> Originally Posted by *LHD21* /forum/post/16425309
> 
> 
> I'm very well aware of the unintended consequences that come with application level systems. As little as a java update could skew things or prevent it from working completely. I prefer appliance level reliability and longevity of service.
> 
> 
> Of course there's always the line of thinking that you simply don't perform any software upgrades but what happens when you have a drive failure and some facet of your application isn't available anylonger?
> 
> 
> Its probably not an issue but old habits die hard.




And on the other extreme of things are companies who see legit products but are either unable to continuously support legacy systems or purposely do not forcing you to pay to upgrade. This particular freeware does seem to work really awesome, at least what playing I've done (I don't have a microphone yet).


----------



## LHD21




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16425731
> 
> 
> REW is not just any old Java program. John Mulcahy, its author, is one seriously smart guy with a lot of experience in signal processing.
> 
> 
> - Terry



I have absolutely no doubt about the app being fantastic. Like I said earlier, old habits die hard. I just get a nagging feeling I'm doing it the wrong way. I probably shouldnt worry too much since I have a dedicated REW laptop. Perhaps I'll satiate myself by getting a better microphone. I see the ECM8000s are about $50. Whats a good mic preamp to go with it?



And just for curiosities sake, what would you guys be using if REW were not available?


----------



## Terry Montlick




> Quote:
> Originally Posted by *LHD21* /forum/post/16426559
> 
> 
> And just for curiosities sake, what would you guys be using if REW were not available?



Other similar products, in no particular order:


ETF

Arta

WinMLS

Easera

DIRAC

TEF20 Analyzer with Sound Lab MLS


- Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *LHD21* /forum/post/16426559
> 
> 
> what would you guys be using if REW were not available?



I started with ETF which works well, but it's not quite as full-featured as the latest version of REW:

Using ETF 



> Quote:
> there's always the line of thinking that you simply don't perform any software upgrades but what happens when you have a drive failure and some facet of your application isn't available anylonger?



I have a separate drive partition where I save all downloaded programs, and of course that's backed up on multiple drives in different locations. Likewise, I keep only Windows and programs on my C: drive, and I use Ghost to make image backups. So no matter what happens to C: I can be back and running in 15 minutes. The value of keeping all data separate from the OS and programs is the OS drive rarely changes and can be backed up less often. And if you do have to restore, none of your data is "restored" to older versions too.


--Ethan


----------



## pepar

There is also backup/sync freeware such as SyncBack that is powerful and easy to use. Upgrading to a registered version in inexpensive, but I have found that the freeware version does everything I need. There is also a PowerToy called SyncToy that is free from Microsoft. With apps like these and the low low cost of storage, internal, external and solid state, there is no reason that any data is ever lost.


----------



## Ethan Winer

Hey, I use SyncBack too! I liked it so much I sent them the money for the Pro version a few years ago. But I prefer the freeware version so I still use that. I was glad to give them the money anyway though. It's a great program. I have more than a dozen profiles for all the data types and multiple round-robin destinations I back up to.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16433946
> 
> 
> Hey, I use SyncBack too! I liked it so much I sent them the money for the Pro version a few years ago. But I prefer the freeware version so I still use that. *I was glad to give them the money anyway though.* It's a great program. I have more than a dozen profiles for all the data types and multiple round-robin destinations I back up to.
> 
> 
> --Ethan



Agreed, Ethan. I do that for quite a few little utilities I find useful.


----------



## notoriousmatty

A few observations with my first acoustic journey. I bought a pair of GIK tri traps and a pair of ATS 4" 24x48 panels and a single 24x24. I put the GIKs in the front wall corners and the 24x48's at the first reflection points of the speakers on the wall. The 24x24 behind the center channel. There is only 18 inches of bare wall between the speakers and the giks next to my 60 inch plasma and the speakers are facing the corners toed in. The ATS stuff seems much better built than the Tri Traps which seem like I would have been able to make with stuff around the house. The tri traps almost have no weight to them. Maybe they forgot to put the acoustic filling in? few questions


1) If I breath in hard with my nose I still get flutter echo in my room. So its still very live. I need more panels in my 11x16 room? Im sitting 8 feet away from the front wall and the back wall is a open closet full of clothes.

2) Where should I put these panels? Ceiling? The first reflection points of the front l/r are covered.

3) The tri traps may have tightened the bass up slightly but are the effective in deadening the wall space behind my speaker?

4) everyone talked about how acoustic treatments would make the biggest difference but the soundstage is still smeared and busy. Do I just need MORE treatment?

Thanks


----------



## unclepauly

First reflection points include ALL first reflection points. So yes ceiling I would say is a must.


Does it hurt your nose to do that because I physically can't make a noise loud enough with my nose to cause an echo I just can't seem to do it.


3/ - yes they deaden


4. ~ Hit all the first reflection points first then work on other suggestions.


----------



## nathan_h

 notoriousmatty ,


Got a photo or three of the room and panel placement? Seems unlikely a single panel on the side wall could get all three first reflection points for the front speakers, but seeing a photo might explain how that is working.


----------



## pepar




> Quote:
> Originally Posted by *notoriousmatty* /forum/post/16436567
> 
> 
> A few observations with my first acoustic journey. I bought a pair of GIK tri traps and a pair of ATS 4" 24x48 panels and a single 24x24. I put the GIKs in the front wall corners and the 24x48's at the first reflection points of the speakers on the wall. The 24x24 behind the center channel. There is only 18 inches of bare wall between the speakers and the giks next to my 60 inch plasma and the speakers are facing the corners toed in. The ATS stuff seems much better built than the Tri Traps which seem like I would have been able to make with stuff around the house. The tri traps almost have no weight to them. Maybe they forgot to put the acoustic filling in? few questions
> 
> 
> 1) If I breath in hard with my nose I still get flutter echo in my room. So its still very live. I need more panels in my 11x16 room? Im sitting 8 feet away from the front wall and the back wall is a open closet full of clothes.
> 
> 2) Where should I put these panels? Ceiling? The first reflection points of the front l/r are covered.
> 
> 3) The tri traps may have tightened the bass up slightly but are the effective in deadening the wall space behind my speaker?
> 
> 4) everyone talked about how acoustic treatments would make the biggest difference but the soundstage is still smeared and busy. *Do I just need MORE treatment?*
> 
> Thanks



Look into "diffusion."


----------



## pepar

I understand that the "thinking" on acoustical treatments is evolving with LEDE being completely out the window now for multichannel listening. Herein lies my dilemma. When I originally build my room, it was recommended that I completely line the cavity behind my false wall with 2" Linacoustic, line the frame around the AT screen with the same material and to install a 2" fiberglass mask over the center channel's baffle - cutout sufficiently for the drivers of course. My screen at the time was a micro-perfed Firehawk and comb filtering was a problem with the aforementioned treatment mitigating it. (Nonetheless, I could never get the center channel EQ'd correctly.)


Now I have moved to a woven AT screen and the material I am reading is making me rethink my treatments behind the wall. (OK, the material - Toole and Holman specifically - actually has me considering swapping my front left and right absorbers for diffusors, but that should probably be the subject of another post.)


Keeping, of course, the SSC bass traps there and the 'glass directly behind each front speaker for first reflection point reasons, should I remove the Linacoustic and leave the wall untreated? Remove and replace the Linacoustic with diffusors?


Is comb filtering from sound reflections in the screen/false wall cavity not an issue with woven screens?


I will probably cross-post this question one or two other places - the SMX thread being one.


TIA!


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16437973
> 
> 
> Now I have moved to a woven AT screen and the material I am reading is making me rethink my treatments behind the wall. (OK, the material - Toole and Holman specifically - actually has me considering swapping my front left and right absorbers for diffusors, but that should probably be the subject of another post.)
> 
> 
> Keeping, of course, the SSC bass traps there and the 'glass directly behind each front speaker for first reflection point reasons, should I remove the Linacoustic and leave the wall untreated? Remove and replace the Linacoustic with diffusors?



This change would affect the reverberation times of the room. If the latter are already at good levels and uniform over frequency, I wouldn't mess with it.


As for first reflection point from the front wall, this depends on the distance of the speakers to the front wall. This reflection will *not* cause image shifting or other distortion of the front sound stage, as will side wall reflections. It has other potential consequences.


Even though your speakers are facing forward, they will typically be very omnidirectional up through at least 250 Hz. A 1/4 wave reflection at 250 Hz and lower corresponds to a speaker to wall distance of about 1 foot or more. If your speaker distance is roughly 1.5 feet or less, then 2+ inches of fiberglass may be effective at treating this potential wave cancellation problem. This is easy to test by temporarily covering the area behind the speaker with something hard, like plywood, and seeing if a dip appears at the expected 1/4 wave frequency.



> Quote:
> Is comb filtering from sound reflections in the screen/false wall cavity not an issue with woven screens?



It is less of an issue, but can still manifest itself as ripple at the highest frequencies.


- Terry


----------



## slider33

This has got me thinking. I have skimmed the thread but have not found an answer for my situation.


I am going to be building a screen wall for my theater, about 18 - 24" deep with a woven screen. I am not going to place the mains behind the screen they will be to the side of the screen in recesses in the screen wall. The center will be on a shelf the same height as the bottom of the screen, directly behind it. I will probably place the sub on the floor with GOM material in front of it.


Should I be treating anything behind the screen wall? Right now the main wall is just unfinished drywall, and I was going to also construct the screen wall of drywall also. I see some people are using fibreglass along the main wall. Is this simply insulation, or is there a special product for it?


I don't imagine I'll get a whole lot of resonance with the sub 2" behind GOM and the center 2" behind the screen, so maybe I don't really need anything back there?


----------



## Terry Montlick




> Quote:
> Originally Posted by *slider33* /forum/post/16439184
> 
> 
> Should I be treating anything behind the screen wall? Right now the main wall is just unfinished drywall, and I was going to also construct the screen wall of drywall also.



Generally, behind the screen wall is an excellent place to stash acoustic treatment, without having to worry about the way it looks. Corner bass traps constructed of semi-rigid fiberglass often fit well here.


- Terry


----------



## slider33




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16439364
> 
> 
> Generally, behind the screen wall is an excellent place to stash acoustic treatment, without having to worry about the way it looks. Corner bass traps constructed of *semi-rigid fiberglass* often fit well here.
> 
> 
> - Terry



Is there a product for this, or is it as simple as cramming some insulation down there?


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16438228
> 
> 
> This change would affect the reverberation times of the room. If the latter are already at good levels and uniform over frequency, I wouldn't mess with it.
> 
> 
> As for first reflection point from the front wall, this depends on the distance of the speakers to the front wall. This reflection will *not* cause image shifting or other distortion of the front sound stage, as will side wall reflections. It has other potential consequences.
> 
> 
> Even though your speakers are facing forward, they will typically be very omnidirectional up through at least 250 Hz. A 1/4 wave reflection at 250 Hz and lower corresponds to a speaker to wall distance of about 1 foot or more. If your speaker distance is roughly 1.5 feet or less, then 2+ inches of fiberglass may be effective at treating this potential wave cancellation problem. This is easy to test by temporarily covering the area behind the speaker with something hard, like plywood, and seeing if a dip appears at the expected 1/4 wave frequency.
> 
> 
> 
> It is less of an issue, but can still manifest itself as ripple at the highest frequencies.
> 
> 
> - Terry



Ummm, yes, thank you, Terry. Seems I should take my own advice and do some measurements before doing anything. FWIW, my front speakers are Omnimount'ed onto the front wall with mere inches between the wall and the cabinet.


----------



## pepar




> Quote:
> Originally Posted by *slider33* /forum/post/16439184
> 
> 
> 
> I am going to be building a screen wall for my theater, about 18 - 24" deep with a woven screen. I am not going to place the mains behind the screen they will be to the side of the screen in recesses in the screen wall. The center will be on a shelf the same height as the bottom of the screen, directly behind it.



Just curious, slider33, why acoustical transparent screen if you are not going to place LCR behind it? As far as syncing the picture and the sounds, that is the bee's knees.


----------



## pepar




> Quote:
> Originally Posted by *slider33* /forum/post/16439416
> 
> 
> Is there a product for this, or is it as simple as cramming some insulation down there?



703 is popular. 2" or 4". This page will enable you to shop and possibly find a lesser expensive alternative. 3.0 pcf is the spec to look for.

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Terry Montlick




> Quote:
> Originally Posted by *slider33* /forum/post/16439416
> 
> 
> Is there a product for this, or is it as simple as cramming some insulation down there?



What pepar said.


- Terry


----------



## slider33




> Quote:
> Originally Posted by *pepar* /forum/post/16439467
> 
> 
> Just curious, slider33, why acoustical transparent screen if you are not going to place LCR behind it? As far as syncing the picture and the sounds, that is the bee's knees.



I have thought about that, and it is a viable option as well. I mainly wanted the mains on the sides for a "business" look, and didn't want to place the center under a regular screen as it would be quite low. Is it really much better to run all the LRC behind it? In this case I would just make the whole screen wall GOM around the screen. I really don't even know if I can fit the mains on the sides anyway as I only have about a foot of space to play with (screen and speakers are about 11' wide combined, room is 12'). Maybe if I do this I can go up a screen size also







.



> Quote:
> Originally Posted by *pepar* /forum/post/16439493
> 
> 
> 703 is popular. 2" or 4". This page will enable you to shop and possibly find a lesser expensive alternative. 3.0 pcf is the spec to look for.
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm



Thanks again


----------



## pepar




> Quote:
> Originally Posted by *slider33* /forum/post/16439662
> 
> 
> I have thought about that, and it is a viable option as well. I mainly wanted the mains on the sides for a "business" look, and didn't want to place the center under a regular screen as it would be quite low. *Is it really much better to run all the LRC behind it?* In this case I would just make the whole screen wall GOM around the screen. I really don't even know if I can fit the mains on the sides anyway as I only have about a foot of space to play with (screen and speakers are about 11' wide combined, room is 12'). Maybe if I do this I can go up a screen size also
> 
> 
> 
> 
> 
> 
> 
> .



Oh yeah!


And for timbre/equalization purposes, locating all three front speakers behind the screen is a plus. Having an AVR or pre/pro with an "automatic" equalization system - such as Audyssey - removes the hassle of tweaking. As you mention, this would also get your L&R away from the wall, too. Check the my home theater website (linked in my sig).


Once you've had LCR behind the picture, you'll have trouble enjoying the home theaters of your mates who do not.


----------



## slider33

Is the rigid fiberglass in the link you posted earlier readily available at most home stores? I have been looking for the 703 on Home Depot's site and I cannot find it on there.


They do have sound absorbent insulation though (several brands). Is this the same idea, just that it can't be easily drilled/stuck to the wall?


----------



## pepar




> Quote:
> Originally Posted by *slider33* /forum/post/16440429
> 
> 
> Is the rigid fiberglass in the link you posted earlier readily available at most home stores? I have been looking for the 703 on Home Depot's site and I cannot find it on there.
> 
> 
> They do have sound absorbent insulation though (several brands). Is this the same idea, just that it can't be easily drilled/stuck to the wall?



The pink fluffy stuff sold by home improvement stores would do the job. What you need is sold through HVAC insulation channels. This company is popular. Seattle and Tuckwila have locations.


----------



## slider33




> Quote:
> Originally Posted by *pepar* /forum/post/16440536
> 
> 
> The pink fluffy stuff sold by home improvement stores would do the job. What you need is sold through HVAC insulation channels. This company is popular. Seattle and Tuckwila have locations.



Excellent, thank you for your time.


----------



## R Harkness

Hey folks, I need some quick opinions here. As mentioned earlier in this thread, I'm doing a home theater reno in a living room.


One issue with this room is that it's a living room right below our bedroom.

Sometimes my wife will go to bed earlier and I want to limit the sound traveling through the floor upstairs into the bedroom. For various reasons we can't do any major acoustic isolation treatment, but what I want to do is at least PRESERVE the isolation I had before this home theater reno. There wasn't too much sound transfer before the reno and my wife never had any problems with the sound at night. (I don't play it loud anyway).


So my fear has been introducing any more pathways for sound to intrude through the ceiling. Which is one reason we dropped the ceiling to add pot lights, rather than risk poking holes into the existing ceiling to add the pot lights.


BUT...of course with all the running of wire and construction, contractors have had to poke many holes in the walls and ceiling. So I have a question on two issues:


1. What should we do to acoustically seal the various holes? Many of them will be re-dry-walled, but some, like in one of the pictures I'm posting, have wires coming out of them.


2. The Screen Wall. As you can see the screen wall has had the drywall taken off. Originally we planned to simply dry-wall it up again (it was being straightened for the screen). But instead, now we plan to fill it with absorptive material, so behind and around the screen will act as an acoustic absorption. (A "dead wall"). So no drywall. But I'm concerned that this could be a route for sound to travel up the cavity into the bedroom above.


Should I be worried about this, given the cavity will be filled with absorption?

Or do I need to somehow have a seal made at the top of the open wall. It's been suggested perhaps to seal it by using spray-in foam. Or perhaps create a dry-wall seal? Any advice?


Thanks. (Please see pictures).











Looking up into screen wall top opening. Above this is our bedroom. Do I need to create a seal up there, or will stuffing the whole wall with absorption be stopping the sound enough as it is?:











A hole in the ceiling where some wires come out. How to acoustically seal this?


----------



## R Harkness

Anyone?


----------



## rutlian

Hang in there Rich,


Experts here are really generous maybe they are just outhere researching for you...too bad I am no expert.


Peter


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/16460254
> 
> 
> Anyone?



Almost nothing you can do will prevent the sound - the bass - from being transmitted though the building elements to the adjacent spaces.


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/16455518
> 
> 
> 2. The Screen Wall. As you can see the screen wall has had the drywall taken off. Originally we planned to simply dry-wall it up again (it was being straightened for the screen). But instead, now we plan to fill it with absorptive material, so behind and around the screen will act as an acoustic absorption. (A "dead wall"). So no drywall. But I'm concerned that this could be a route for sound to travel up the cavity into the bedroom above.
> 
> 
> Should I be worried about this, given the cavity will be filled with absorption?



Yes, be very worried. In fact, *don't do it!* Even with a lot of absorption, much sound will travel right up to the second floor. The porous absorption material will not contain the sound.


Instead, put up at least one layer of drywall (2 is better) to make a proper 2-leaf wall with fiberglass-filled airspace. Put the screen acoustical absorption in front of this inner drywall.


- Terry


----------



## R Harkness




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16460673
> 
> 
> Yes, be very worried. In fact, *don't do it!* Even with a lot of absorption, much sound will travel right up to the second floor. The porous absorption material will not contain the sound.
> 
> 
> Instead, put up at least one layer of drywall (2 is better) to make a proper 2-leaf wall with fiberglass-filled airspace. Put the screen acoustical absorption in front of this inner drywall.
> 
> 
> - Terry



Thank you VERY much for the response Terry. The idea of not drywalling and instead filling the cavity with acoustic absorption material was actually suggested to me by the company doing my room acoustic treatments. But I was obviously still worried about sound transfer to the upstairs and your post adds to that concern.


If you don't mind:


1. So, in reference to the second last picture in my post, looking up into the wall cavity toward the ceiling, would it not be possible to create some sort of inner seal at the point were the drywall starts in that picture? Just to stop the sound travelling upward?


2. If I go the drwall route you suggest, I'm not sure where the drywall layer would go. If we just drywalled it like normal, the drywall would be placed over the wall studs. However, for various reasons, I don't have room to push the screen out any more into the room, so I won't have room to thicken the wall with acoustic material overtop a normal drywall application.

Which is why we were thinking of leaving off the drywall, giving us room to place acoustic material between the studs.


In your drywall suggestion, where would the drywall be placed? Some sort of layer sort of set back into the studs somewhat, with a layer of acoustic material overtop that behind the screen?


We are right at the stage of doing the screen wall so advice like yours is very

pertinent. It will help me decide if I bother putting acoustic material into the screen wall or (possibly make my life easier and) just have the screen wall drywalled and hang the screen.


BTW, we have a 24" wide by 6" deep drop down bulkhead built down from the room ceiling, so we can put acoustic absorption above the screen wall, and some over the general seating area as well. I was just thinking that making the screen wall "dead" would help too.


Many thanks!!!!!!


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/16461086
> 
> 
> Thank you VERY much for the response Terry. The idea of not drywalling and instead filling the cavity with acoustic absorption material was actually suggested to me by the company doing my room acoustic treatments. But I was obviously still worried about sound transfer to the upstairs and your post adds to that concern.
> 
> 
> If you don't mind:
> 
> 
> 1. So, in reference to the second last picture in my post, looking up into the wall cavity toward the ceiling, would it not be possible to create some sort of inner seal at the point were the drywall starts in that picture? Just to stop the sound travelling upward?



Maybe, but not having a standard interior wall covering such as gypsum board over studs is not what I'd consider a "best practice" for either home theater or general residential construction. I wouldn't offer any advice along those lines. Depending on where you live, it may not even be permitted by local building code.



> Quote:
> 2. If I go the drwall route you suggest, I'm not sure where the drywall layer would go. If we just drywalled it like normal, the drywall would be placed over the wall studs. However, for various reasons, I don't have room to push the screen out any more into the room, so I won't have room to thicken the wall with acoustic material overtop a normal drywall application.



You don't have a couple of inches? There are numerous compromises required in building a home theater. I'm afraid this is one of them.










- Terry


----------



## R Harkness

Ok Terry, thank you. That's helpful.


Any comments about creating seals for the other holes in my ceiling from running wires? You can see one of these holes in my last photo.


----------



## nathan_h




> Quote:
> Originally Posted by *R Harkness* /forum/post/16461467
> 
> 
> Ok Terry, thank you. That's helpful.
> 
> 
> Any comments about creating seals for the other holes in my ceiling from running wires? You can see one of these holes in my last photo.



If air can get through, high frequency sounds can get through.


If physical elements are touching (like studs and drywall) then big thumping bass wil transfer throughout the house.


It is VERY worth it to loose as many as six inches on all sides to effectively build space between the theater room and the rooms surrounding it.


----------



## R Harkness




> Quote:
> Originally Posted by *nathan_h* /forum/post/16461669
> 
> 
> If air can get through, high frequency sounds can get through.
> 
> 
> If physical elements are touching (like studs and drywall) then big thumping bass wil transfer throughout the house.
> 
> 
> It is VERY worth it to loose as many as six inches on all sides to effectively build space between the theater room and the rooms surrounding it.



Thank you. But full isolation is simply impossible in my situation (aside from financially). It's a living room and it has a grand, open doorway (no doors) with columns from the 1920s. There is no sealing off this room.


But it's been ok for many years in terms of not too much sound escaping to the upstairs bedroom, so as I said I'm just concerned about changes to the room (new holes/openings) creating additional sound leakage, which might push what has been acceptable to unacceptable noise leakage.


----------



## pepar

Like I said, almost nothing you can do will prevent the sound - the bass - from being transmitted though the building elements to the adjacent spaces.


----------



## BRAC

Hi All,


Sorry, I searched this LONG thread first, but I can't seem to find a good explanation for my present concerns.


I am almost finished covering my light colored walls and ceiling with dark drapes/fabric for the purpose of creating a bat cave like environment for my theater. I'm going with fabric as a temporary solution because it's easily reversable and I may totally overhaul the theater in the not to distant future. Anyway, while trying so hard to improve my viewing environment, I think I may have just compromised my listening environment.







The drapes and fabrics of choice are made of cotton, polyester and acrylic. My current room is only about 12' x 11' with a 7-7.5' tiled drop ceiling. And, I also have some corner bass trapping and acoustic panels in place.


Did I just create a "dead" listening space??? I apologize in advance if this sounds a bit novice.










Thanks...


----------



## Terry Montlick




> Quote:
> Originally Posted by *BRAC* /forum/post/16464233
> 
> 
> Did I just create a "dead" listening space??? I apologize in advance if this sounds a bit novice.



No. The fabric, per se, has very little sound absorption unless it is HEAVY. For example, a _*very*_ heavy velour fabric (40 ounces/square yard!) has significant absorption starting above 1 kHz. It reaches its peak at around 10 kHz.


Typical thin cotton and synthetic should have little acoustical effect, and are relatively transparent. Which means that you can always hide additional porous absorption behind it if you need to do so.


- Terry


----------



## allredp




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16466336
> 
> 
> No. The fabric, per se, has very little sound absorption unless it is HEAVY. For example, a _*very*_ heavy velour fabric (40 ounces/square yard!) has significant absorption starting above 1 kHz. It reaches its peak at around 10 kHz.
> 
> 
> Typical thin cotton and synthetic should have little acoustical effect, and are relatively transparent. Which means that you can always hide additional porous absorption behind it if you need to do so.
> 
> 
> - Terry



Great insight Terry--thanks for chiming in as you and other professionals do! Much appreciated...


----------



## BRAC




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16466336
> 
> 
> No. The fabric, per se, has very little sound absorption unless it is HEAVY. For example, a _*very*_ heavy velour fabric (40 ounces/square yard!) has significant absorption starting above 1 kHz. It reaches its peak at around 10 kHz.
> 
> 
> Typical thin cotton and synthetic should have little acoustical effect, and are relatively transparent. Which means that you can always hide additional porous absorption behind it if you need to do so.
> 
> 
> - Terry



Great! Thanks for that very helpful info...


Btw, I was most concerned with the black suede drapes I'm using on the side walls, because they are actually "moderately" thick blackout drapes with a 100% polyester surface and a 100% acrylic backing.


Any thoughts? Thanks...


----------



## Ethan Winer




> Quote:
> Originally Posted by *BRAC* /forum/post/16464233
> 
> 
> Did I just create a "dead" listening space???



Terry already gave you good answers. I'll add that a home theater in a small room should be mostly on the dead side. That removes the "small room sound" which in turn makes movie sound tracks sound larger. But you need more than thin curtains to achieve this.


--Ethan


----------



## BRAC




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16466933
> 
> 
> Terry already gave you good answers. I'll add that a home theater in a small room should be mostly on the dead side. That removes the "small room sound" which in turn makes movie sound tracks sound larger. But you need more than thin curtains to achieve this.
> 
> 
> --Ethan



Exactly the answers I was hoping for.


Thanks Ethan and Terry...


----------



## R Harkness

I've been having the same anxiety about ending up with too dead a room. Mine's a living room/home theater. The company who will be applying a fabric covering over a 12 x 12' portion of the ceiling, wants to put a 1" (or is it 1/2"?) layer of foam core on to the ceiling, then put the fabric over it. With the big thick rug, many curtains and huge sofa in a relatively small room (15 x 13') I'm worried this will make the sound too dead. I know it should help with some first ceiling reflections, but at the same time I don't want the room to "sound" odd, like entering a recording studio.


----------



## Dennis Erskine

Foam core!? What specific product. This smells bad already.


----------



## weverb

Well, I had some interesting results today. I made a 5.5" thick 2'x4' bass trap today and tried it in a few different spots. It seemed to only help very little in the 70-90Hz. range. There was also no real visable benefit in the waterfall graphs either.


Graph response from on top of the desk:

 


Graph from opposite front corner:

 


Final graph next to couch:

 


Here is a link to one of my posts with pictures and layout so you can understand the trial placements:

http://www.avsforum.com/avs-vb/showt...1#post16359511 


Any thoughts on the results?


----------



## Terry Montlick




> Quote:
> Originally Posted by *weverb* /forum/post/16468694
> 
> 
> Well, I had some interesting results today. I made a 5.5" thick 2'x4' bass trap today and tried it in a few different spots. It seemed to only help very little in the 70-90Hz. range.
> 
> ...
> 
> Any thoughts on the results?



I think your expectations may be too high for these frequencies and a single 2'x4' corner bass trap. You need a lot more coverage to have a significant effect as low as 70 Hz.


But I would start by calibrating your sub with respect to your mains. It is pretty high.


- Terry


----------



## R Harkness




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16468385
> 
> 
> Foam core!? What specific product. This smells bad already.



Maybe I got that wrong. I'm pretty sure he mentioned some kind of "core"...and I think he mentioned "Rocksil" (sp?)


----------



## weverb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16468826
> 
> 
> But I would start by calibrating your sub with respect to your mains. It is pretty high.



It is high due to house curve and to get 30Hz. to "sound" the same volume as 100Hz. What is interesting is, when I play the receiver's test tones, the subs are 1 dB lower than each main (74dB versus 75dB.).


----------



## weverb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16468826
> 
> 
> I think your expectations may be too high for these frequencies and a single 2'x4' corner bass trap. You need a lot more coverage to have a significant effect as low as 70 Hz.



I figured by testing the two different corners, I would get an average of the two if I had two traps to place. Also, I would have been fine with no change in the frequency response, but have a noticeable change some where in the waterfall. Besides, those were the only two corners that I could possible put anything substantial for a bass trap. The last corner available has a large clock and chair in it. There is no room for anything bigger than 1' wide.


From the testing results, I will probably get "more bang for my buck" focusing on broadband traps some more. I have not done anything on the ceiling yet!







Basically like you said previously:



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16359858
> 
> 
> With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways.
> 
> 
> 
> 
> 
> 
> 
> Like the Energizer Bunny, it keeps on going! Especially low frequency sound. This means that subwoofer frequencies can easily escape into larger spaces, and may not be an issue. Higher frequencies, on the other hand, are more readily trapped between parallel walls, and may create problems.



Another question for you. What might happen if I place a broadband trap between the two M&K tripoles on the rear wall? Is that a bad idea based on their design?


Thanks for your help and comments!


----------



## Terry Montlick




> Quote:
> Originally Posted by *weverb* /forum/post/16470164
> 
> 
> I figured by testing the two different corners, I would get an average of the two if I had two traps to place.



Which corners did you try? Can you show us on the diagram you posted in the other thread?


- Terry


----------



## weverb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16473608
> 
> 
> Which corners did you try? Can you show us on the diagram you posted in the other thread?
> 
> 
> - Terry



Here is the layout again:

 


I tried the corner in the far upper left in the dinning area and the corner in the far upper right where the desk is. I placed the trap about mid way up the wall and had it straddling the wall-wall corner. As close to a 45 degree angle as I could. The area that showed the good result was on the left side of the couch/table straddling the wall-floor corner at a 45 degree angle. I already have a 3.5"x2'x3' bass trap on the right side of the couch/table between them and the clock on the floor.


----------



## unclepauly

Do you guys recommend treating first reflection points then running audyssey if I don't have the budget for bass traps yet? Or just leave audyssey off? Also the same question goes for when I do get the bass traps, should I run audyssey afterwards or just try to get as close to optimal as possible with absorption? I tried audyssey before I treated the reflection points and to be honest it sounded like my speakers were turned into a bullhorn, it sounded really weird.


Onkyo 605 and polk rti speakers with a bic h100 sub.


----------



## nathan_h




> Quote:
> Originally Posted by *unclepauly* /forum/post/16475682
> 
> 
> Do you guys recommend treating first reflection points then running audyssey if I don't have the budget for bass traps yet? Or just leave audyssey off? Also the same question goes for when I do get the bass traps, should I run audyssey afterwards or just try to get as close to optimal as possible with absorption? I tried audyssey before I treated the reflection points and to be honest it sounded like my speakers were turned into a bullhorn, it sounded really weird.
> 
> 
> Onkyo 605 and polk rti speakers with a bic h100 sub.



Treatments (as many as you can afford) -- then run audyssey, after every change of traps or speaker or furniture position.


Follow the tips in the Audyssey thread to get the best results.


----------



## Terry Montlick




> Quote:
> Originally Posted by *weverb* /forum/post/16474989
> 
> 
> I tried the corner in the far upper left in the dinning area and the corner in the far upper right where the desk is.



Hmm, I suspected this. Remember when I said,



> Quote:
> With those open doorways, and I assume the opening to the playroom, your "room" is a lot bigger than you think. Sound isn't smart enough to know that the room stops at open doorways.



Well, this is particulary true of the lowest bass frequencies. Subwoofer frequencies don't "see" the dining area as much by way of a room. It is too open for them to generate the strongest room modes at the wimpy dining room corner-shapes which you consider the room boundaries. Big bass waves will not be confined by these (at least horizontally), but blast through into the adjacent spaces. If there were doors enclosing the dining area, things would be very different. But without doors, these wave more likely consider *all* all the space open to it the "room." This has a larger and more complex shape than than the dining area rectangle.


So the important acoustical low frequency corners of the actual room are probably not the little ones in the dining area, but the two at the right-most part of the playroom, and those somewhere in the kitchen and the foyer, which you haven't completely shown, and maybe corners in whatever is beyond the bottom left door out of the dining area.


- Terry


----------



## unclepauly




> Quote:
> Originally Posted by *nathan_h* /forum/post/16475995
> 
> 
> Treatments (as many as you can afford) -- then run audyssey, after every change of traps or speaker or furniture position.
> 
> 
> Follow the tips in the Audyssey thread to get the best results.



OK I'll check that thread out thanks.


----------



## giomania




> Quote:
> Originally Posted by *unclepauly* /forum/post/16476397
> 
> 
> OK I'll check that thread out thanks.



Follow the link in my signature to see the Audyssey Setup Guide mentioned.


Mark


----------



## unclepauly




> Quote:
> Originally Posted by *giomania* /forum/post/16476540
> 
> 
> Follow the link in my signature to see the Audyssey Setup Guide mentioned.
> 
> 
> Mark



Wow. Very nice, exactly the type of thing I was looking for. Very much appreciated.


----------



## weverb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16476296
> 
> 
> Well, this is particulary true of the lowest bass frequencies. Subwoofer frequencies don't "see" the dining area as much by way of a room. It is too open for them to generate the strongest room modes at the wimpy dining room corner-shapes which you consider the room boundaries. Big bass waves will not be confined by these (at least horizontally), but blast through into the adjacent spaces. If there were doors enclosing the dining area, things would be very different. But without doors, these wave more likely consider *all* all the space open to it the "room." This has a larger and more complex shape than than the dining area rectangle.
> 
> 
> So the important acoustical low frequency corners of the actual room are probably not the little ones in the dining area, but the two at the right-most part of the playroom, and those somewhere in the kitchen and the foyer, which you haven't completely shown, and maybe corners in whatever is beyond the bottom left door out of the dining area.



Terry,


First off, thanks for sticking with me and explaining things so us non-experts can understand. Your comments make total sense. The only interesting thing I will add is that when I walk around while playing filtered pink noise of 30-300Hz., the bass sounds heavy/boomy in those small dining area corners. More so than the kitchen and foyer. Also in the playroom, the far upper right corner is composed of all windows. Basically the entire playroom outer walls are windows. If I remember correctly, this means all the low Hz. are going to just pass through them. That in combo with the very open plan is probably why I cannot get my set-up to play lower than 15Hz. Would placing a trap in a corner constructed of windows really do anything? What about placing it in a door way? In a sense, to create a door and try to seal the other smaller spaces off.


Another question for you. What might happen if I place a broadband trap between the two M&K tripoles (a pair of K4's) on the rear wall? Is that a bad idea based on their design?


Thanks again for all your help.


----------



## Ethan Winer




> Quote:
> Originally Posted by *weverb* /forum/post/16474989
> 
> 
> Here is the layout again



The biggest problem I see is you have a reflecting wall right behind your head.


--Ethan


----------



## weverb




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16477791
> 
> 
> The biggest problem I see is you have a reflecting wall right behind your head.
> 
> 
> --Ethan



I have started addressing that with this panel (listening ear level is about in-line with the top of the couch cushions):

 


But I am also wondering, what might happen if I place a broadband trap between the two M&K tripoles (a pair of K4's) on the rear wall? Is that a bad idea based on their design?


----------



## pepar

For what it's worth, if this were my space, I'd pull the couch out from the wall enough and place the rear surrounds *behind* the couch firing UP. Our bedroom system is set up that way and it is the only way to get the proper surround effect.


----------



## weverb




> Quote:
> Originally Posted by *pepar* /forum/post/16478624
> 
> 
> For what it's worth, if this were my space, I'd pull the couch out from the wall enough and place the rear surrounds *behind* the couch firing UP. Our bedroom system is set up that way and it is the only way to get the proper surround effect.



Ideally if space and WAF allowed, the couch would be pulled away. Unfortunately, there is not much space and the WAF factor is more in charge than I.







I am lucky I am getting to do some panels at all. She said they had to blend in as much as possible. It has not been easy trying to duplicate a custom wall treatment on fabric!


----------



## pepar




> Quote:
> Originally Posted by *weverb* /forum/post/16478913
> 
> 
> Ideally if space and WAF allowed, the couch would be pulled away. Unfortunately, there is not much space and the WAF factor is more in charge than I.
> 
> 
> 
> 
> 
> 
> 
> I am lucky I am getting to do some panels at all. She said they had to blend in as much as possible. It has not been easy trying to duplicate a custom wall treatment on fabric!


----------



## bpape

To jump backward a bit....


Doing one corner then another is still giving you way too little coverage to get any kind of real idea of what you're going to get. As Terry said, you simply need some thickness and size to deal with the bottom end to have a significant impact for either frequency response and/or decay time.


Bryan


----------



## Avad

Hi,

This is my first post and i am new to acoustical treatments. I have a media room 13'x10'x8'. The below image shows my media room setup. I will be purchasing six 2'x4' 2" panels(Owens Corning 703). Can anyone please help me with the placements of these panels in the room? Also is my speaker setup correct?











thanks for the help


----------



## funlvr1965




> Quote:
> Originally Posted by *Avad* /forum/post/16491287
> 
> 
> Hi,
> 
> This is my first post and i am new to acoustical treatments. I have a media room 13'x10'x8'. The below image shows my media room setup. I will be purchasing six 2'x4' 2" panels(Owens Corning 703). Can anyone please help me with the placements of these panels in the room? Also is my speaker setup correct?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> thanks for the help



Try to find your first reflection points, this is where you will install you panels. once in your seating area have someone with a full lenght mirror (cheap mirror usually found at wallmart or target) along the wall and when you can see the a speaker in the mirror that is a reflection point and this where you would mount a panel. Mark the midpoint of the panel and mount that to the height of the tweeter in the speaker. Find a reflection point for every seat, you may may surprised at how many panels you end up with. As for your speaker placement, looks good except try and move the sub to the front or side walls if you can otherwise you will get too much localization since its so close. Im sure others will chime in with their recommendations, good luck


----------



## pepar




> Quote:
> Originally Posted by *funlvr1965* /forum/post/16491416
> 
> 
> Try to find your first reflection points, this is where you will install you panels. once in your seating area have someone with a full lenght mirror (cheap mirror usually found at wallmart or target) along the wall and when you can see the a speaker in the mirror that is a reflection point and this where you would mount a panel. Mark the midpoint of the panel and mount that to the height of the tweeter in the speaker. Find a reflection point for every seat, you may may surprised at how many panels you end up with. As for your speaker placement, looks good except try and move the sub to the front or side walls if you can otherwise you will get too much localization since its so close. Im sure others will chime in with their recommendations, good luck



If you have billiard skills, sit in each seat and visualize the line into the wall that produces a strike on the speaker. It's weird, but it worked for me. The mirror think is a PITA.


For your room, the wall just behind the couch will be the biggest challenge to achieving good sound. IMO. I would try to put 4" of 703 there bust behind the heads of listeners.


----------



## Weasel9992




> Quote:
> Originally Posted by *Avad* /forum/post/16491287
> 
> 
> Hi,
> 
> This is my first post and i am new to acoustical treatments. I have a media room 13'x10'x8'. The below image shows my media room setup. I will be purchasing six 2'x4' 2" panels(Owens Corning 703). Can anyone please help me with the placements of these panels in the room? Also is my speaker setup correct?



The other guys have already nailed the placement advice, so I'll just add this: that's a pretty small room, and you're seated right up against the back wall. You're going to need some pretty significant bass trapping in there. Typical placement would be in the corners, on the back wall and on the front wall behind the speakers. The 2" panels will go along way toward dealing with short reflections, but they're not going to do a thing to help with the low end room modes, which will be the biggest problem by far in a room that size and shape.


Frank


----------



## Avad

Thanks a lot guys, I guess i will mount two on each side walls after finding the reflection points and may be two on the back walls. Or the best bet would be is to mount one near each corner and two on the side walls?


pepar: for the back wall maybe i will convert the two 2" into a 4" and mount it behind the sofa.

Weasel9992: I know the room is small, i wish i had a bigger room


----------



## Weasel9992




> Quote:
> Originally Posted by *Avad* /forum/post/16491736
> 
> 
> Thanks a lot guys, I guess i will mount two on each side walls after finding the reflection points and may be two on the back walls. Or the best bet would be is to mount one near each corner and two on the side walls?
> 
> 
> pepar: for the back wall maybe i will convert the two 2" into a 4" and mount it behind the sofa.
> 
> Weasel9992: I know the room is small, i wish i had a bigger room



If you put two up on the back wall you'll probably end up moving them in the near future. Then again, the back wall will be the closest boundary layer to your ears, so it makes some sense for now. 2" panels won't do anything much below 500Hz, so there's no need to bother with corner placement I would think.


Rooms that size work well all the time. You just have to think all the way through treating them is all...get the right stuff in the right places.










Frank


----------



## R Harkness

Here's an odd one. I hope someone has some advice.


In my home theater reno room we recently built down a ceiling bulkhead (just framed at this point). We had move the existing AC pipe a little. My contractor used some form of extension pipe material from, I think, Home Depot. Added about 2 1/2 feet of extension with this pipe and now the output is mounted in the bulkhead.


But just tonight, when our air-conditioning turned on (probably for the first time) I noticed that the sound coming from that newly mounted AC vent sounded odd. It seems to have picked up a rubber-pipe-like resonance, so instead of an atonal rush of air like all the rest of our vents, it's making more of a solid, musical note tone. I find it quite distracting.


Any suggestions? I was thinking maybe I was hearing this tone because, unlike the rest of the AC vents in our house the piping is currently exposed and the bulkhead has not been completed. Except that when I listen up close it's like I can hear the resonant tone coming right out of the vent, not from around the tube.


Any advice? Can I change the resonance of this tube? I know it's some cheap stuff; are there any alternatives likely to make this issue go away?


Many thanks.


----------



## Dan Woodruff

Rich H,


I am no expert at AC installation but you might try replacing the new extension with a length of flex.


----------



## Dennis Erskine

Remove the vent. Music still there?


----------



## nathan_h




> Quote:
> Originally Posted by *weverb* /forum/post/16478913
> 
> 
> Ideally if space and WAF allowed, the couch would be pulled away. Unfortunately, there is not much space and the WAF factor is more in charge than I.
> 
> 
> 
> 
> 
> 
> 
> I am lucky I am getting to do some panels at all. She said they had to blend in as much as possible. It has not been easy trying to duplicate a custom wall treatment on fabric!



Pull the couch out, set a table behind for her favorite nick-knacks.


You could pile up some bass traps under it, invisibly, and perhaps just get thin high frequncy stuff on the wall behind your ears.


Here is a random internet photo of the idea, but not against a wall.


----------



## R Harkness




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16516577
> 
> 
> Remove the vent. Music still there?



I wish I could do that easily to experiment but I can't. One end is now built into a valance over the screen area







So I'm hoping for a likely solution, warranting taking the thing out.


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/16518719
> 
> 
> But just tonight, when our air-conditioning turned on (probably for the first time) I noticed that the sound coming from that newly mounted AC vent sounded odd. It seems to have picked up a rubber-pipe-like resonance, so instead of an atonal rush of air like all the rest of our vents, it's making more of a solid, musical note tone. I find it quite distracting.



Like blowing over the top of a bottle? If so, then in effect that is what is happening somewhere in what you've added or across the opening to what you added. Somehow you need to interrupt the airflow across the "bottletop" or otherwise disturb the resonance. Picture in your mind what was added and "look" for where the bottletop might be.


Is there any fiberglass lining the ductwork?


----------



## Dan Woodruff

It seems I misunderstood. I thought he said the new ductwork is making the noise. If it's the register then it should be a simple and easy fix. I put new registers (decorative) on mine that have no directional/shut-off 'baffles'. Nothing in them to generate noise at all.


----------



## pepar




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/16519347
> 
> 
> It seems I misunderstood. I thought he said the new ductwork is making the noise. If it's the register then it should be a simple and easy fix. I put new registers (decorative) on mine that have no directional/shut-off 'baffles'. Nothing in them to generate noise at all.



I believe the new ductwork _is_ making the noise. but the noise Rich described suggests that it is a resonance, not air turbulance from a grill.


----------



## Tonmeister2008




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/2176537
> 
> 
> First, (B) is wrong. Virtually every surface is a first reflective surface (speaking of walls). "B" is actually treating those early reflections which meet the listener's ears within a time frame described by Helmut Haas (further researched by Toole and Olive). Depending upon the delay due to the longer path to the ear will result in the sound being perceived as a distortion, or echo. As well, sounds reflecting off a surface suffer timbre shift. Next, you don't care a twit about "early reflections" that don't intersect the listening position.



I would not agree totally with the statement that "sound reflecting off a surface suffers timbre shift." It depends on the relative level, spectrum, delay and direction of the reflection. There is a fair amount of research (nicely summarized in Floyd Toole's book) that suggests reflections in typical furnished domestic rooms generally do little harm and, in fact, generally do some good (increases spaciouness, image widening, and intelligibility). Of course, some absorption is required and diffusion is good too. We advocate wide-band absorption and diffusion - which eliminates the use of 1 inch of foam or fiberglass: 3-4 inches is preferred. There is also evidence that we adapt to the room acoustics and the reflections in the multichannel recording (coming from the side/rear speakers) will dominate the spatial/timbre impressions you hear.


I just posted an article on my blog about Harman International Reference Listening Rooms used for listener training, critical listening and product testing. We made the acoustical treatment removable so we can test many of these controversial questions about the perceptual effects of room treatment on sound quality. Stay tuned.


----------



## Dennis Erskine

I was in LA last week. I would have enjoyed seeing your rooms.


I agree "too dead" is a bane; but, diffusion and reflection strategies would need to have some basis in the quality of the off axis response of the speakers, yes?


We do adapt well to, or listening through, some acoustic issues. Is there any recent research (at Harmon) with respect to any resultant listener fatigue as a result?


----------



## R Harkness




> Quote:
> Originally Posted by *pepar* /forum/post/16519265
> 
> 
> Like blowing over the top of a bottle? If so, then in effect that is what is happening somewhere in what you've added or across the opening to what you added. Somehow you need to interrupt the airflow across the "bottletop" or otherwise disturb the resonance. Picture in your mind what was added and "look" for where the bottletop might be.
> 
> 
> Is there any fiberglass lining the ductwork?



Thanks.


The noise only came about once the 2 1/2 foot extension tube was added, to extend the end/grill to a new location in the new ceiling bulkhead. I've bent the tube around while air is flowing through it wondering if it would affect the tone but it doesn't. It's just standard tubing (plastic, I think). No fiberglass.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *pepar* /forum/post/16519409
> 
> 
> I believe the new ductwork _is_ making the noise. but the noise Rich described suggests that it is a resonance, not air turbulance from a grill.



I read it the same as you did then. Sorry for the confusion.


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/16520402
> 
> 
> Thanks.
> 
> 
> The noise only came about once the 2 1/2 foot extension tube was added, to extend the end/grill to a new location in the new ceiling bulkhead. I've bent the tube around while air is flowing through it wondering if it would affect the tone but it doesn't. It's just standard tubing (plastic, I think). No fiberglass.



Perhaps, then, the tube's "mouth" is the bottletop and the air from the existing duct strikes it at such an angle so as to excite the column of air in the tube. Proof of that would be to shorten or lengthen (compress or stretch) the tube. If the tone changes pitch, then that's what it is.


----------



## Tonmeister2008




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16519998
> 
> 
> I was in LA last week. I would have enjoyed seeing your rooms.
> 
> 
> I agree "too dead" is a bane; but, diffusion and reflection strategies would need to have some basis in the quality of the off axis response of the speakers, yes?
> 
> 
> We do adapt well to, or listening through, some acoustic issues. Is there any recent research (at Harmon) with respect to any resultant listener fatigue as a result?



Hi Dennis,

Next time you are in LA, let me know and I can arrange a visit to Harman. Yes, the off axis response should be factored into decisions on treatment but any good home theatre consultant worth his or her commission should be able to recommend loudspeakers that have good off-axis response.


I've done some recent work on room acoustic adaptation. It appears we adapt very quickly (a few seconds), but only up to a point. In the case where the room has a lot of high level late reflections (30-80 msec) listeners will not adapt to the room acoustics, and complain about it's excessive liveliness, loss in clarity,etc. I didn't measure fatigue but if listeners have to work harder to understand dialog/lyrics,etc it wouldn't surprise me if fatigue were not an issue.


----------



## firebrick

at what point does superchunk bass traps become too small? I have several that are 17x17x24 that I use in the corners. I was thinking about making some for where the walls and ceiling meet that are 12x12x17. Is this becoming too small to make a significant difference? Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.


----------



## pepar




> Quote:
> Originally Posted by *firebrick* /forum/post/16532508
> 
> 
> at what point does superchunk bass traps become too small? I have several that are 17x17x24 that I use in the corners. I was thinking about making some for where the walls and ceiling meet that are 12x12x17. Is this becoming too small to make a significant difference? Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.



No doubt about it, the shallower traps do not reach as low. But I haven't seen any comparisons between the different sizes. I think the conmventional wisdom is to make them as deep as possible . . and install as much as possible. Not sure about felt. GOM definitely works, and burlap is usually very open and will work as well.


----------



## Terry Montlick




> Quote:
> Originally Posted by *firebrick* /forum/post/16532508
> 
> 
> Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.



I have measured light velour felt (7.5 oz.) from Jo-Ann, and it has no significant attenuation at low frequencies. Jo-Ann burlap is better only at frequencies much higher than the bass region. The latter is transparent enough to be used as speaker grill cloth.


- Terry


----------



## firebrick




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16534001
> 
> 
> I have measured light velour felt (7.5 oz.) from Jo-Ann, and it has no significant attenuation at low frequencies. Jo-Ann burlap is better only at frequencies much higher than the bass region. The latter is transparent enough to be used as speaker grill cloth.
> 
> 
> - Terry



Excuse me for not understanding but you are saying felt is ok for bass traps correct?


----------



## Terry Montlick




> Quote:
> Originally Posted by *firebrick* /forum/post/16534097
> 
> 
> Excuse me for not understanding but you are saying felt is ok for bass traps correct?



Yes, certainly the light-weight felt which you are likely to encounter at a fabric store such as Jo-Ann. Heavy theatrical curtain felt is a different story.


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *firebrick* /forum/post/16532508
> 
> 
> at what point does superchunk bass traps become too small? I have several that are 17x17x24 that I use in the corners. I was thinking about making some for where the walls and ceiling meet that are 12x12x17. Is this becoming too small to make a significant difference? Also I cover mine with felt as that seems to pass air through it fairly easily. Is this a mistake? Do i need to use GOM or some type of burlap? Thanks.



12x12x17 is too small I'd say. 17x17x24 is the way we build them. That said, it's probably a lot better than nothing at all in the corners.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16534197
> 
> 
> 12x12x17 is too small I'd say. 17x17x24 is the way we build them. That said, it's probably a lot better than nothing at all in the corners.



Frank, have you worked with 24x24x34 and if so, what performance differences have you noticed/measured?


----------



## whumpf

If there is enough space, would it be better to make the superchunks square instead of triangular? A 12" square column would have approx. the same volume as a 17 x 17 x 24 triangle trap.


----------



## pepar




> Quote:
> Originally Posted by *whumpf* /forum/post/16534492
> 
> 
> If there is enough space, would it be better to make the superchunks square instead of triangular? A 12" square column would have approx. the same volume as a 17 x 17 x 24 triangle trap.



It would be better to make it triangular at 17x17x24.


----------



## whumpf




> Quote:
> Originally Posted by *pepar* /forum/post/16534647
> 
> 
> It would be better to make it triangular at 17x17x24.



Why?


----------



## firebrick




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16534197
> 
> 
> 12x12x17 is too small I'd say. 17x17x24 is the way we build them. That said, it's probably a lot better than nothing at all in the corners.
> 
> 
> Frank



the small ones were to go all the way around the ceiling, just trying to find out if it would even be worth it, i dunno, alot of trouble if no gains. i also wondered whether making my sides 24x24x34 would help considerably or just leave them at 17x17x24


----------



## firebrick

I also thought about getting some of your 6" panel traps from gik and just hanging them from the ceiling but I only read about corners being important. I still cant figure out your coffee table and pillar traps, where do you put them to smooth bass response?


----------



## pepar




> Quote:
> Originally Posted by *whumpf* /forum/post/16534939
> 
> 
> Why?



Don't know the scientific reason, but the design is a proven performer. Do some research - http://forum.studiotips.com/viewforu...f4cb76f7c6b9e4


----------



## Weasel9992




> Quote:
> Originally Posted by *firebrick* /forum/post/16535024
> 
> 
> I also thought about getting some of your 6" panel traps from gik and just hanging them from the ceiling but I only read about corners being important. I still cant figure out your coffee table and pillar traps, where do you put them to smooth bass response?



Ceilings are important too...it depends on the specific room and specific situation, but floor/ceiling standing waves can be just as big an issue as length related or width related ones.


Those traps (an others like them) can be deployed in a bunch of different places, but commonly they're put along the walls of a room, in the corners or on the front wall...anywhere you need trapping but don't want something that looks quite so much like an acoustic panel.


Frank


----------



## pepar




> Quote:
> Originally Posted by *firebrick* /forum/post/16535014
> 
> 
> the small ones were to go all the way around the ceiling, just trying to find out if it would even be worth it, i dunno, alot of trouble if no gains. i also wondered whether making my sides 24x24x34 would help considerably or just leave them at 17x17x24



24x24x34 will absorb lower.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/16535162
> 
> 
> 24x24x34 will absorb lower.



Yep. The point is, where corners are concerned the more square footage you can cover at greater depth, the better. Of course, that only works to a certain extent because you also have to be able to use the room...


Frank


----------



## whumpf




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16535186
> 
> 
> Yep. The point is, where corners are concerned the more square footage you can cover at greater depth, the better. Of course, that only works to a certain extent because you also have to be able to use the room...
> 
> 
> Frank



This would seem to suggest that a 24 x 24 square would absorb lower than a 24 x 24 x 34 triangle?


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16535186
> 
> 
> Yep. The point is, where corners are concerned the more square footage you can cover at greater depth, the better. Of course, that only works to a certain extent because you also have to be able to use the room...
> 
> 
> Frank













The OP mentioned them, so it seemed like an option. Space, or the lack thereof, is a big factor in the layout in a lot our our home theaters. And 24x24x34 corner traps are humongous.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/16535208
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The OP mentioned them, so it seemed like an option. Space, or the lack thereof, is a big factor in the layout in a lot our our home theaters. And 24x24x34 corner traps are humongous.



Oh yeah...I agree with you 100%.


Frank


----------



## R Harkness




> Quote:
> Originally Posted by *R Harkness* /forum/post/16455518



Folks, as usual the HT reno is moving s-l-o-w-l-y. Which gives me time to worry and ruminate on my decisions. As I mentioned earlier in this thread the plan is to make this open screen wall into a sound absorber, stuffing the whole thing with acoustic material, behind and around the screen, then covered with a layer of fabric. (Instead of drywalling).


The main thing I want to do is help control bass frequencies given I have to place the speakers pretty close to this wall - about 14 inches to the back of the speaker and somewhat in the corners. We will be having a large "bass trap" put over-top the screen.


My question is: Is it worth it filling the screen wall this way? Will it really help out much, in terms of controlling sound/bass absorption? The whole thing would be easier to drywall if it's not going to do much for me acoustically. FWIW there will be curtains and 5 hanging velvet fabric panels

in each of the screen wall corners behind the speakers (don't know how much that would help things). Also, if I instead drywalled this wall there's a little room between the side edges of the screen and the side walls. I'd have room to place 9" wide, 7 foot tall, 3" deep absorption material between the side ends of the screen and the side walls, if that might help things.


Advice? Opinions?


Thanks.


----------



## Ethan Winer




> Quote:
> Originally Posted by *R Harkness* /forum/post/16551798
> 
> 
> Is it worth it filling the screen wall this way?



Yes, but with only a few inches depth you'll want to use rigid fiberglass rather than the typical fluffy type.


--Ethan


----------



## ggraef

I'm experimenting with acoustics in an unusual shaped room. In terms of acoustics issues, does anyone have an idea how the meeting of two walls at 135 degrees compares to 90 degrees, especially at the ceiling (90 degrees there)? Is it likely to be worth trapping the 8' length of the wall interface? Or maybe just the ceiling corner? The room has 2 90 degree corners, 2 135 degree corners (and one missing corner that is open to a hall).


Thanks!

Gerry


----------



## R Harkness




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16554002
> 
> 
> Yes, but with only a few inches depth you'll want to use rigid fiberglass rather than the typical fluffy type.
> 
> 
> --Ethan



Thanks Ethan. Looks like we have about 3 1/2" depth for filling in that wall. Do you suggest just stacking fibreglass boards solid, or do we need any space in between each board?


----------



## Ethan Winer

Solid, no space.


----------



## Ethan Winer




> Quote:
> Originally Posted by *ggraef* /forum/post/16554625
> 
> 
> does anyone have an idea how the meeting of two walls at 135 degrees compares to 90 degrees



A corner is a corner, so that's still a great place for bass traps.



> Quote:
> Is it likely to be worth trapping the 8' length of the wall interface?



The more total corner surface you treat, the better. Always.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *ggraef* /forum/post/16554625
> 
> 
> The room has 2 90 degree corners, 2 135 degree corners (and one missing corner that is open to a hall).



So the room is 5-sided, with one missing corner? If so, do as Ethan says. I am curious. Can you give the dimensions of the walls and also the corner angle which has the open hall? I may do a quick 2-D finite element analysis to identify the room modes, just for the heck of it.


- Terry


----------



## R Harkness




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16559370
> 
> 
> Solid, no space.



Much obliged, that helps a lot.


Rich


----------



## R Harkness

Oh man, another quick issue has just arisen:


Whether to order some black velvet "backed" or "un-backed" for acoustic reasons.


On either side of my screen I'll have hanging velvet panels, on automated roller panels, which will open and close to reveal the screen (and do various AR widths masking).


So I'll have Five 18" wide by 7 foot tall hanging velvet panels in a stacked-behind-each-other position on either side of the screen. (I figure this may serendipitously help out the acoustics of the speakers in front of them, perhaps a tiny bit).


Anyway, behind those velvet panels is the screen wall which, as discussed above, I'll be filling with 3 1/2" of fibre-board, covered with fabric, for acoustic treatment.


So the question is: I believe the black velvet can be ordered either "backed" (which would help it adhere on to surfaces, as I'll be doing around the screen wall), or "un-backed" which is typically how you want to order fabric that you want sound to pass through.


Do you think it would matter in this case if all the velvet is backed? Would that create a barrier between the back of the side speakers and the acoustic material on the other side of the velvet panels, nullifying some of the effect of the acoustic treatment? Or is the backing a negligible effect in this case?


Thanks.


----------



## ggraef




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16559430
> 
> 
> So the room is 5-sided, with one missing corner? If so, do as Ethan says. I am curious. Can you give the dimensions of the walls and also the corner angle which has the open hall? I may do a quick 2-D finite element analysis to identify the room modes, just for the heck of it.
> 
> 
> - Terry



Here is a quick drawing of the room size. I haven't measured the angles, but by the sizes of the walls (and a little geometry) they should be very close to 135 degrees.


I did do some tests with REW and found that the room starts to clean up nicely with trapping (and Audyssey MultEQ also works quite well). The nodes are very position dependent, however.


Thanks!

Gerry


----------



## Taz1

Guys, I just want to make sure that I am on the right track.


1" Linacoustic RC on lower side walls about 42" from ground , the whole back wall and side wall next the front wall.


1 1/2" Acoustaboard Black Acoustic Tiles by Certainteed on the top portion of the wall and some on the front ceiling.


4" bass traps in each corner.


Is this correct?


Thanks Taz


----------



## funlvr1965




> Quote:
> Originally Posted by *Taz1* /forum/post/16560840
> 
> 
> Guys, I just want to make sure that I am on the right track.
> 
> 
> 1" Linacoustic RC on lower side walls about 42" from ground , the whole back wall and side wall next the front wall.
> 
> 
> 1 1/2" Acoustaboard Black Acoustic Tiles by Certainteed on the top portion of the wall and some on the front ceiling.
> 
> 
> 4" bass traps in each corner.
> 
> 
> Is this correct?
> 
> 
> Thanks Taz




The experts here are going to tell you that all of that is too much absorbtion and may tend to make the room dead sounding, just find primary reflection points and treat those areas


----------



## Ethan Winer




> Quote:
> Originally Posted by *R Harkness* /forum/post/16560006
> 
> 
> Do you think it would matter in this case if all the velvet is backed?



Having a backing is okay for corner bass traps, but probably not for absorbers at reflection points.


--Ethan


----------



## Taz1

So, I treat the primary reflection areas on ceiling and walls. Do I use 703 3" or 2" boards with GOM?


Do I need to do anything with lower part the walls?


What do I use to treat the area behind the false wall?



Thank you for all the Help.










Here is the link to my HT build.

http://www.avsforum.com/avs-vb/showthread.php?t=1148971


----------



## R Harkness

Super...thanks Ethan.


----------



## firebrick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16563774
> 
> 
> Having a backing is okay for corner bass traps, but probably not for absorbers at reflection points.
> 
> 
> --Ethan



why is backed velvet ok to use for corner bass traps if air has a hard time going through it?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Taz1* /forum/post/16564491
> 
> 
> So, I treat the primary reflection areas on ceiling and walls. Do I use 703 3" or 2" boards with GOM?



Sure.



> Quote:
> Do I need to do anything with lower part the walls?



What matters most is ear level, and a few feet above and below.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *firebrick* /forum/post/16564942
> 
> 
> why is backed velvet ok to use for corner bass traps if air has a hard time going through it?



Because the backing serves as a sort of membrane that increases LF absorption. More here:

Density Report 


--Ethan


----------



## firebrick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16571262
> 
> 
> Because the backing serves as a sort of membrane that increases LF absorption. More here:
> 
> Density Report
> 
> 
> --Ethan



So the backed velvet would actually make my superchunk corner traps absorb better than using gom?? That is nice to know, velvet looks so much better.


----------



## Taz1

Thank you Ethan.


----------



## Taz1

I called a local HVAC supply company and they carry JM 800 duct board and OC 1400. I don't see them on Bobgold site:

http://www.bobgolds.com/AbsorptionCoefficients.htm I do see 814 as comparable to OC 703.


I did find these specs. on 800. Will these work for the first reflections and maybe double them for Bass traps?

http://www.jm.com/insulation/perform..._microaire.pdf 

http://www.owenscorning.com/quietzon..._DataSheet.pdf 



125hz 250hz 500hz 1000hz 2000hz 4000hz NRC

0.17 0.86 1.14 1.07 1.02 0.98 1.00 -OC 703


0.17 0.63 1.10 1.05 1.04 1.06 0.95 -JM 800 type


0.14 0.72 1.15 1.12 1.06 1.07 1.00 -OC 1400


They seem very close to OC 703.


----------



## Terry Montlick

EI-800 duct board is a heavy duty product with a density in the range 3pcf-6pcf. The EI rating for fiberglass board is a measure of flexural stiffness. You can substitute this for OC 703 or 705.


- Terry


----------



## Taz1

Thank you Terry.


I just found out that I need an account with the company that sells the OC 1400. However, its good to know that I am able to use IE 800 and I don't need an account with that company.


----------



## R Harkness




> Quote:
> Originally Posted by *R Harkness* /forum/post/16455518



Ugh.


Well I finally got the quote from a company to do the acoustic treatment of this screen wall - that is filling it with acoustic absorption, then covered with fabric and hanging my screen.


A bit over $4,000!


I'm thinkin' my bank account can only handle so much and that's too much to add at this point.


Does anyone think I lose much if I just drywall the screen wall instead? (It would certainly be less of a headache to do so; I'm just not sure how much

benefit I'd lose if I did that over making the wall absorptive...the room will have lots of absorptive surfaces throughout - thick shag rug, massive stuffed sectional sofa, lots of velvet curtain etc).


(I suppose another route perhaps I could get my contractor, the one doing the rest of the work in the room, to fill it with some sort of absorption and essentially "do it ourselves."...??)


----------



## Taz1




> Quote:
> Originally Posted by *R Harkness* /forum/post/16577895
> 
> 
> Ugh.
> 
> 
> Well I finally got the quote from a company to do the acoustic treatment of this screen wall - that is filling it with acoustic absorption, then covered with fabric and hanging my screen.
> 
> 
> A bit over $4,000!
> 
> 
> I'm thinkin' my bank account can only handle so much and that's too much to add at this point.
> 
> 
> Does anyone think I lose much if I just drywall the screen wall instead? (It would certainly be less of a headache to do so; I'm just not sure how much
> 
> benefit I'd lose if I did that over making the wall absorptive...the room will have lots of absorptive surfaces throughout - thick shag rug, massive stuffed sectional sofa, lots of velvet curtain etc).
> 
> 
> (I suppose another route perhaps I could get my contractor, the one doing the rest of the work in the room, to fill it with some sort of absorption and essentially "do it ourselves."...??)




WOW! $4K. Someone correct me if I am wrong, but if it just have screen wall, couldn't you just stuff it with R-11 put the drywall on. Put Linc. RC or 2" OC 703 or a similer product on the wall and make a 2x4 frame for the screen to go on?


the price for JM 800. $58.70 for 48" X 120" x2".


----------



## pepar

I think all you can do - at a reasonable price - is to stuff the cavities with fiberglass and look into something to provide some de-coupling between the studs and the drywall you are about to install. Of course, the "reasonable price" thingy only happens - as you might have guessed now - if you do it yourself, at least on the fiberglass stuffing part.


----------



## R Harkness

I'm a bit confused here.


You guys are talking about both stuffing the screen wall AND doing drywall.


I thought putting on the drywall defeats the purpose of what we were trying to do.

That is, make the screen wall a big "trap" or acoustic absorber to help tame base frequencies in the room, especially behind the L/C/R speakers. I was led to believe that

putting a layer of drywall over the acoustic material would be self-defeating, since it would tend to put a barrier between the acoustic absorption material and the sound it is supposed to absorb. Which is why when you make acoustic panels you surround them with fabric, not some hard substance like drywall or wood.


So I'm unclear about how you think I'd combine drywalling the screen wall, while simultaneously achieving the goal of making it an acoustic absorber. I thought that to make the screen wall act, in essence, like a giant acoustic panel I'd be covering it in fabric, not drywall.


(I'll have a big bass trap on the ceiling above the screen, and could put one near the back of the room hidden in the ceiling treatment as well. I don't know if that will be good enough that I could just forgo trying to make the screen wall an absorber as well).

??


----------



## unclepauly

Yeah I thought drywall wasn't very transmissive for sound?


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/16578152
> 
> 
> I'm a bit confused here.



Maybe me, too.











> Quote:
> You guys are talking about both stuffing the screen wall AND doing drywall.
> 
> 
> I thought putting on the drywall defeats the purpose of what we were trying to do.
> 
> That is, make the screen wall a big "trap" or acoustic absorber to help tame base frequencies in the room, especially behind the L/C/R speakers. I was led to believe that
> 
> putting a layer of drywall over the acoustic material would be self-defeating, since it would tend to put a barrier between the acoustic absorption material and the sound it is supposed to absorb. Which is why when you make acoustic panels you surround them with fabric, not some hard substance like drywall or wood.
> 
> 
> So I'm unclear about how you think I'd combine drywalling the screen wall, while simultaneously achieving the goal of making it an acoustic absorber. I thought that to make the screen wall act, in essence, like a giant acoustic panel I'd be covering it in fabric, not drywall.
> 
> 
> (I'll have a big bass trap on the ceiling above the screen, and could put one near the back of the room hidden in the ceiling treatment as well. I don't know if that will be good enough that I could just forgo trying to make the screen wall an absorber as well).
> 
> ??



My apologies if I missed/forgot where you were not going to drywall and only stuff. I thought acoustical isolation was your only goal. In that case, I would not only place 'glass between the studs, but probably extend the 'glass several inches *beyond* the plane of the wall studs. The thicker it is, the lower the absorption will extend. This will also provide acoustical isolation by reducing/preventing the lows from getting to the studs to be transmitted to the floor above.


----------



## giomania

I have been following this thread for awhile, and am finally getting around to planning the installation of room treatments. I have taken in a lot of information from this thread, so many thanks to all the contributors. I have a few questions before I finalize the plan and obtain the material. My dedicated theater is 27'-3" x 19'-8" x 7'-6.5" and is finished in drywall.


My basic plan was to build a false wall approximately 18"-24" out from the front wall and place SSC bass traps in the front vertical and horizontal corners. I would cover the remainder of the front wall with 2" JM814, and would also use this for the SSC bass traps. JM 814 (2") is what they have in stock at my local SPI store.


I would re-hang my non-perforated screen on the false wall, and cover the remainder of the false wall with GOM FR701. The L/C/R speakers would sit in front of the false wall, as I have plenty of room. I could place the L/R speakers behind the false wall, but it is not a requirement. Due to accessibility requirements on the right side of the front wall, the false wall would not cover the entire 19'-8" length. The false wall would stop short about 3'-4' on each side, and I would hang curtains between the end of the false wall and the side wall.


I would also buy enough 2" JM814 to make side wall and ceiling FRP panels.


So, here are my questions:


1) For the SSC bass traps, I was thinking to make them all the 24" x 24" x 34" triangles, but would I be better off with some of the 17" x 17" x 24" triangles?


2) Should any of the SSC bass traps have FRK / FSK on the face?


3) Are the curtains OK in front of the SSC bass traps?


4) Do I need to ensure there is a gap between the SSC bass traps and the front wall treatment to eliminate the edge effect?


5) I want to use some material to absorb some of the sound of my projector fan, and would appreciate some recommendations. I cannot build a total enclosure, as I cannot cool it.


Thanks for any help.


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/16588089
> 
> 
> I have been following this thread for awhile, and am finally getting around to planning the installation of room treatments. I have taken in a lot of information from this thread, so many thanks to all the contributors. I have a few questions before I finalize the plan and obtain the material. My dedicated theater is 27'-3" x 19'-8" x 7'-6.5" and is finished in drywall.
> 
> 
> My basic plan was to build a false wall approximately 18"-24" out from the front wall and place SSC bass traps in the front vertical and horizontal corners. I would cover the remainder of the front wall with 2" JM814, and would also use this for the SSC bass traps. JM 814 (2") is what they have in stock at my local SPI store.
> 
> 
> I would re-hang my non-perforated screen on the false wall, and cover the remainder of the false wall with GOM FR701. The L/C/R speakers would sit in front of the false wall, as I have plenty of room. I could place the L/R speakers behind the false wall, but it is not a requirement. Due to accessibility requirements on the right side of the front wall, the false wall would not cover the entire 19'-8" length. The false wall would stop short about 3'-4' on each side, and I would hang curtains between the end of the false wall and the side wall.
> 
> 
> I would also buy enough 2" JM814 to make side wall and ceiling FRP panels.
> 
> 
> So, here are my questions:
> 
> 
> 1) For the SSC bass traps, I was thinking to make them all the 24" x 24" x 34" triangles, but would I be better off with some of the 17" x 17" x 24" triangles?



If you have the space in your room (and your budget) for the biguns, I'd recommend that that's what you use. They will reach lower in what they absorb.



> Quote:
> 2) Should any of the SSC bass traps have FRK / FSK on the face?



The facing is not necessary/will not improve performance with the SSC design. I think it adds expense.



> Quote:
> 3) Are the curtains OK in front of the SSC bass traps?



I think so, but an acoustician on this thread should advise if there is any particular material that should be avoided.



> Quote:
> 4) Do I need to ensure there is a gap between the SSC bass traps and the front wall treatment to eliminate the edge effect?



No.


I would strongly recommend that you consider an acoustically transparent screen. At the entry-level, DIY stage, Sheerweave 4500 is dirt cheap. Once you have become accustomed to the sound coming from the picture, you will not be able to enjoy the theaters of your friends w/o AT screens.


----------



## Weasel9992




> Quote:
> Originally Posted by *giomania* /forum/post/16588089
> 
> 
> 1) For the SSC bass traps, I was thinking to make them all the 24" x 24" x 34" triangles, but would I be better off with some of the 17" x 17" x 24" triangles?



The bigger, the better to a point. 24"x24"x34" will do a better job down lower, so if they're just as easy to do, go for it.



> Quote:
> Originally Posted by *giomania* /forum/post/16588089
> 
> 
> 3) Are the curtains OK in front of the SSC bass traps?



Sure, but theater velour is pretty absorbent in the high end. You won't affect the bass trapping performance at all though.



> Quote:
> Originally Posted by *giomania* /forum/post/16588089
> 
> 
> 5) I want to use some material to absorb some of the sound of my projector fan, and would appreciate some recommendations. I cannot build a total enclosure, as I cannot cool it.



I'm not sure what you mean by this. Do you mean that you want the treatment reduce some of the fan noise? If so, then it absolutely won't. One thing has nothing to do with the other. The only way to reduce fan noise is to use the projector on the reduced energy setting or to build an enclosure, which you said you didn't want to do.


Frank


----------



## giomania




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16589893
> 
> 
> I'm not sure what you mean by this. Do you mean that you want the treatment reduce some of the fan noise? If so, then it absolutely won't. One thing has nothing to do with the other. The only way to reduce fan noise is to use the projector on the reduced energy setting or to build an enclosure, which you said you didn't want to do.
> 
> 
> Frank



Frank,


Thanks for the response. The intent is to prevent the sound from coming forward in the room. I was thinking that rigid fiberglass absorbs noise, so would it not reduce the fan noise as well?


Mark


----------



## giomania




> Quote:
> Originally Posted by *pepar* /forum/post/16588331
> 
> 
> No.
> 
> 
> I would strongly recommend that you consider an acoustically transparent screen. At the entry-level, DIY stage, Sheerweave 4500 is dirt cheap. Once you have become accustomed to the sound coming from the picture, you will not be able to enjoy the theaters of your friends w/o AT screens.



Jeff,


Thanks for the response. Was the edge effect regarding the SSC traps actually discussed here? I only recall seeing a passing remark.


For the AT screen, when I upgrade my projector to a Laser DLP







, I will look into switching the screen. My projector is perfectly Optimized (by William Phelps) to my Stewart StudioTek 130. The center channel is right below the screen, and I have the screen mounted as high as possible.


Mark


----------



## Weasel9992




> Quote:
> Originally Posted by *giomania* /forum/post/16590298
> 
> 
> Frank,
> 
> 
> Thanks for the response. The intent is to prevent the sound from coming forward in the room. I was thinking that rigid fiberglass absorbs noise, so would it not reduce the fan noise as well?



No, not the way you're thinking. You'd need a solid wall, air tight...hence the issue of the enclosure. Acoustic treatment will do nothing to reduce the fan noise because it'll just find a flanking path elsewhere.


Frank


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/16590407
> 
> 
> Jeff,
> 
> 
> Thanks for the response. Was the edge effect regarding the SSC traps actually discussed here? I only recall seeing a passing remark.
> 
> 
> For the AT screen, when I upgrade my projector to a Laser DLP
> 
> 
> 
> 
> 
> 
> 
> 
> , I will look into switching the screen. My projector is perfectly Optimized (by William Phelps) to my Stewart StudioTek 130. The center channel is right below the screen, and I have the screen mounted as high as possible.
> 
> 
> Mark



M,


My understanding of edge effect has to do with the edges of speaker cabinets; is there another context? If not, then I don't think the "edge effect" has an . . effect at low frequencies. The chunk traps go tight into the corners. The straddling-sheet-of-fiberglass corner traps must touch the walls. Panels at mid-wall benefit from a gap, but it's not related to the kind of edge effect I just described.


J


----------



## dsmith1

Hey all,


I am installing in wall speakers in a basement. I was thinking of using rigid fiberglass (oc type 475) behind the speakers to minimize any hard reflections from the concrete walls. Also, I was going to use the fiberglass to line enclosures for in-ceiling speakers to minimize bleed through in the floor above. Am I doing the right thing or should I do something else? If this is right which way should the foil side face, or should it be peeled off entirely?


Thanks for any help you can offer. I have been researching acoustics, but it is not an easy subject to understand.


----------



## giomania




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16590650
> 
> 
> No, not the way you're thinking. You'd need a solid wall, air tight...hence the issue of the enclosure. Acoustic treatment will do nothing to reduce the fan noise because it'll just find a flanking path elsewhere.
> 
> 
> Frank



I guess my intent was to flank the path of the sound towards the rear of the room. Do you think that would work to reduce the level?


Thanks.


Mark


----------



## giomania




> Quote:
> Originally Posted by *BasementBob* /forum/post/7669011
> 
> 
> pepar:
> 
> 
> Studiotips superchunks work best isolated. If you have no other treatment in the room, superchunks are perfect.
> 
> 
> Putting them up against a bunch of other absorbtion reduces the edge effect boost, but
> 
> a) they're still deep absorbtion (good)
> 
> b) they're still in corners (all modes active in tri-corners, good)



Jeff, here is the post I saw which generated my "edge effect" question.


Mark


----------



## kainers

I have a pretty small room, and was going to use some soffit style moulding to hide my wiring.

http://www.invitinghome.com/crown_mo...-sunnyvale.htm 


I was wondering, maybe I should make the soffits, so I can bass trap with them. Every soffit I see is pretty big, I'd like to keep it around 5"x5" or. Would that be too small to effectively trap the cieling corners?


Thanks!


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/16592362
> 
> 
> Jeff, here is the post I saw which generated my "edge effect" question.
> 
> 
> Mark



I don't recall the context, but it might have been wrt the absorption of adjacent treatment, not the SSC traps. The SSC traps I've seen all have some sort of framing that serves to hold them in place, whereas flat panel - "broadband" - absorbers can be mounted without a frame increasing, according to those that argue it, their effectiveness. I don't recall seeing any data on that though; perhaps it is one of those things that are accepted on faith.







Perhaps Bob is available for comment.


Here is a post that might give you more insight.


----------



## Terry Montlick

pepar,


I'm not Bob, but can comment on the "edge effect" for absorbers. While there may be some contribution from exposed edges, there is a significant increase in absorption at edges even if the sides of the absorber are masked off/baffled. This has been studied a lot (the earliest journal paper I have on it is from 1930!), and is due to diffraction effects.


- Terry


----------



## giomania




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16597208
> 
> 
> pepar,
> 
> 
> I'm not Bob, but can comment on the "edge effect" for absorbers. While there may be some contribution from exposed edges, there is a significant increase in absorption at edges even if the sides of the absorber are masked off/baffled. This has been studied a lot (the earliest journal paper I have on it is from 1930!), and is due to diffraction effects.
> 
> 
> - Terry



Thanks Terry.


So, to apply this to my original question, would it be OK to "butt" the front wall absorption panels 2" JM 814 right up to the edge of my 34-inch face SSC corner traps, which will also be made from JM 814?


Mark


----------



## Terry Montlick




> Quote:
> Originally Posted by *giomania* /forum/post/16597246
> 
> 
> Thanks Terry.
> 
> 
> So, to apply this to my original question, would it be OK to "butt" the front wall absorption panels 2" JM 814 right up to the edge of my 34-inch face SSC corner traps, which will also be made from JM 814?
> 
> 
> Mark



By abutting two pieces of JM 814 against each other, you will not get an edge effect from either at this common edge. If you left a gap between them, it would have to be roughly comparable in size to the wavelengths involved. So the performance of both absorbers will be reduced a bit compared to ones which have a good distance between them.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16597208
> 
> 
> pepar,
> 
> 
> I'm not Bob, but can comment on the "edge effect" for absorbers. While there may be some contribution from exposed edges, there is a significant increase in absorption at edges even if the sides of the absorber are masked off/baffled. This has been studied a lot (the earliest journal paper I have on it is from 1930!), and is due to diffraction effects.



Hi, Terry. Does the edge effect have an effect on absorption of LF? And the effect that it does have (on any absorber), is it absorptive or diffusive? I ask this because of your use of the word "diffraction."


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16597878
> 
> 
> Hi, Terry. Does the edge effect have an effect on absorption of LF?



Yes, pepar. The edge effect occurs when the dimensions of an absorbent surface become as small as (or smaller than) a wavelength.


> Quote:
> And the effect that it does have (on any absorber), is it absorptive or diffusive? I ask this because of your use of the word "diffraction."



It is absorptive. Diffraction in this case refers to the bending of waves toward the absorber. This bending causes the absorber to "capture" extra waves which would otherwise not be in its geometric path. More sound is absorbed near the edges as compared with any other part of the absorber.


- Terry


----------



## cuzed2

OH NO; I had just managed to get mind around absorption and diffusion, when diffraction had to come into play










Bragg's Angle anyone...??


----------



## Terry Montlick




> Quote:
> Originally Posted by *cuzed2* /forum/post/16600849
> 
> 
> OH NO; I had just managed to get mind around absorption and diffusion, when diffraction had to come into play
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Bragg's Angle anyone...??













Sorry, but I don't make the rules. Nature does.










- Terry


----------



## KERMIE

Are there some pictures of the "edge effect" you are discribing somewhere?


----------



## Terry Montlick




> Quote:
> Originally Posted by *KERMIE* /forum/post/16601985
> 
> 
> Are there some pictures of the "edge effect" you are discribing somewhere?



Yes, as a matter of fact. With new and fast computer techniques, we can now get numerical solutions and graphical plots for acoustical equations which were previously impractical to compute. Here is a 2005 paper by Yasuhito Kawai and Hiroshige Meotoiwa, "Estimation of the Area Effect of Sound Absorbent Surfaces by Using a Boundary Integral Equation":

http://www.jstage.jst.go.jp/article/ast/26/2/123/_pdf 


I don't advise wading through the math.







Just have a look at Figure 2. The arrows are sound velocity vectors near an absorber (impedance boundary) and hard surface (rigid boundary). Notice how arrows which would have otherwise hit the rigid boundary angle toward the impedance boundary when they get close.


- Terry


----------



## funlvr1965




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16534001
> 
> 
> I have measured light velour felt (7.5 oz.) from Jo-Ann, and it has no significant attenuation at low frequencies. Jo-Ann burlap is better only at frequencies much higher than the bass region. The latter is transparent enough to be used as speaker grill cloth.
> 
> 
> - Terry



Terry I went to Joan fabrics today and found black Royal velvet. The material seems to pass the blow test ok and would love to use it because it sucks up light great and I want to use it to cover my bass traps and highfrequency wall traps but do you think it is suitable to use for what Im trying to do?

Thanks in advance


----------



## Terry Montlick




> Quote:
> Originally Posted by *funlvr1965* /forum/post/16604448
> 
> 
> Terry I went to Joan fabrics today and found black Royal velvet. The material seems to pass the blow test ok and would love to use it because it sucks up light great and I want to use it to cover my bass traps and highfrequency wall traps but do you think it is suitable to use for what Im trying to do?
> 
> Thanks in advance



Just fine for bass traps, probably just fine for wideband wall absorption. The blow-through test is amazingly good. If it offers just a little resistance, the fabric most likely blocks just a few dB of the highest frequencies. There are some real dogs of fabrics out there sold for use in acoustical panels. The blow-through test nabs 'em. You can easily feel a lot of resistance to your breath. You can go blue in the face trying to blow through at least one of them.










You probably have the advantage (as do most) of not having specific engineering goals for your room besides "make it sound good."







That gives you a lot of latitude!


- Terry


----------



## CJO




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16605286
> 
> 
> Just fine for bass traps, probably just fine for wideband wall absorption. The blow-through test is amazingly good. If it offers just a little resistance, the fabric most likely blocks just a few dB of the highest frequencies. There are some real dogs of fabrics out there sold for use in acoustical panels. The blow-through test nabs 'em. You can easily feel a lot of resistance to your breath. You can go blue in the face trying to blow through at least one of them.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You probably have the advantage (as do most) of not having specific engineering goals for your room besides "make it sound good."
> 
> 
> 
> 
> 
> 
> 
> That gives you a lot of latitude!
> 
> 
> - Terry



On the subject. Are there any decently acoustically transparent fabrics that don't look like burlap?


Thanks,

CJ


----------



## Taz1




> Quote:
> Originally Posted by *funlvr1965* /forum/post/16604448
> 
> 
> Terry I went to Joan fabrics today and found black Royal velvet. The material seems to pass the blow test ok and would love to use it because it sucks up light great and I want to use it to cover my bass traps and highfrequency wall traps but do you think it is suitable to use for what Im trying to do?
> 
> Thanks in advance



funlvr1964 thanks for posting. I may have to look into that material this afternoon.





Hi Terry, Do you think I can use the black Royal velvet to cover my false wall or look into GOM or Dazian?


The black Royal velvet may look nice with my velvet AC panels.


Thanks Tas


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16602443
> 
> 
> Yes, as a matter of fact. With new and fast computer techniques, we can now get numerical solutions and graphical plots for acoustical equations which were previously impractical to compute. Here is a 2005 paper by Yasuhito Kawai and Hiroshige Meotoiwa, "Estimation of the Area Effect of Sound Absorbent Surfaces by Using a Boundary Integral Equation":
> 
> http://www.jstage.jst.go.jp/article/ast/26/2/123/_pdf
> 
> 
> I don't advise wading through the math.
> 
> 
> 
> 
> 
> 
> 
> Just have a look at Figure 2. The arrows are sound velocity vectors near an absorber (impedance boundary) and hard surface (rigid boundary). Notice how arrows which would have otherwise hit the rigid boundary angle toward the impedance boundary when they get close.
> 
> 
> - Terry





> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16605286
> 
> 
> Just fine for bass traps, probably just fine for wideband wall absorption. The blow-through test is amazingly good. If it offers just a little resistance, the fabric most likely blocks just a few dB of the highest frequencies. There are some real dogs of fabrics out there sold for use in acoustical panels. The blow-through test nabs 'em. You can easily feel a lot of resistance to your breath. You can go blue in the face trying to blow through at least one of them.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You probably have the advantage (as do most) of not having specific engineering goals for your room besides "make it sound good."
> 
> 
> 
> 
> 
> 
> 
> That gives you a lot of latitude!
> 
> 
> - Terry



Whew. Going forward, I will try to limit my "advice" on this thread to pointing to Bob Gold's charts and where to purchase fiberglass. I clearly know squat about acoustics.


----------



## R Harkness

Oh...my gawd...I'm going insane.


Every time I think I know what I'm doing I talk to another contractor and come back with more questions.


As written earlier, we have opened up the screen wall, no drywall, just a bare stud wall. We are going to fill it with absorbtive material then staple fabric over the wall, then place the screen on the wall.


The question is: WHAT ABSORPTIVE MATERIAL TO USE?


My contractor suggested Roxul, as he's worked with it before. I looked it up and noticed some people saying it's a ***** to work with, suggesting harder mineral wool boards (e.g. Rockwood) or Fibreglass boards (e.g. OC 73 or a local made equivolent OFI 48).


We just have to get this stuff in between the studs, then cover the whole thing with fabric. What should we use? Which material would be easiest (and perhaps least messy) to work with?


A company that supplies such materials - GlassCell - suggested using SAFB material.


Also suggested putting a lining of linacoustic over whatever we stuff between the studs.


Opinions?


----------



## Terry Montlick




> Quote:
> Originally Posted by *CJO* /forum/post/16605476
> 
> 
> On the subject. Are there any decently acoustically transparent fabrics that don't look like burlap?
> 
> 
> Thanks,
> 
> CJ



Have a look at Guilford Wilshire 2735. Its acoustical transparency is excellent, as good IMO to be used as speaker grill cloth. Very close behind is Guilford Lido 2858. In the "next tier," marginal for use as speaker grill cloth but still excellent for covering wide band absorbers (and not extremely burlap-looking), are Guilford's Bailey 2299 and Spinel 3582, Acoustimac DMD fabric, and C.F. Stinson Galaxy.


- Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/16606945
> 
> 
> Oh...my gawd...I'm going insane.
> 
> 
> Every time I think I know what I'm doing I talk to another contractor and come back with more questions.



The answer is simple. Stop listening to contractors, and tell them what *you* want!







The advice provided by the members here on acoustically absorptive materials is by and large excellent.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/16606945
> 
> 
> Oh...my gawd...I'm going insane.
> 
> 
> Every time I think I know what I'm doing I talk to another contractor and come back with more questions.
> 
> 
> As written earlier, we have opened up the screen wall, no drywall, just a bare stud wall. We are going to fill it with absorbtive material then staple fabric over the wall, then place the screen on the wall.
> 
> 
> The question is: WHAT ABSORPTIVE MATERIAL TO USE?
> 
> 
> My contractor suggested Roxul, as he's worked with it before. I looked it up and noticed some people saying it's a ***** to work with, suggesting harder mineral wool boards (e.g. Rockwood) or Fibreglass boards (e.g. OC 73 or a local made equivolent OFI 48).
> 
> 
> We just have to get this stuff in between the studs, then cover the whole thing with fabric. What should we use? Which material would be easiest (and perhaps least messy) to work with?
> 
> 
> A company that supplies such materials - GlassCell - suggested using SAFB material.
> 
> 
> Also suggested putting a lining of linacoustic over whatever we stuff between the studs.
> 
> 
> Opinions?





> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16607015
> 
> 
> The answer is simple. Stop listening to contractors, and tell them what *you* want!
> 
> 
> 
> 
> 
> 
> 
> The advice provided by the members here on acoustically absorptive materials is by and large excellent.
> 
> 
> - Terry










http://www.bobgolds.com/AbsorptionCoefficients.htm 


The "3pcf" density spec is what you should look for when you compare. Within materials with that density, see what you can purchase most economically. Here in the US, many of us buy from this company . You may not want to make a road trip, so I would suggest looking for a similar company in GTO.


In terms of the terminology, HVAC insulation = good, and acoustical insulation = bad. It is all the same, but the appearance of the word "acoustical" adds $$$.


----------



## Weasel9992




> Quote:
> Originally Posted by *CJO* /forum/post/16605476
> 
> 
> On the subject. Are there any decently acoustically transparent fabrics that don't look like burlap?
> 
> 
> Thanks,
> 
> CJ



Guilford FR701 doesn't look like burlap.


Frank


----------



## CJO




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16606955
> 
> 
> Have a look at Guilford Wilshire 2735. Its acoustical transparency is excellent, as good IMO to be used as speaker grill cloth. Very close behind is Guilford Lido 2858. In the "next tier," marginal for use as speaker grill cloth but still excellent for covering wide band absorbers (and not extremely burlap-looking), are Guilford's Bailey 2299 and Spinel 3582, Acoustimac DMD fabric, and C.F. Stinson Galaxy.
> 
> 
> - Terry



Great- this is exactly what I need.


Thanks!

CJ


----------



## CJO




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16607662
> 
> 
> Guilford FR701 doesn't look like burlap.
> 
> 
> Frank



LOL- that's actually what I was thinking of when I asked since I didn't like the coarse weave of the 701







Maybe it's just because the sample is so small that it doesn't look good to me.


CJ


----------



## Terry Montlick




> Quote:
> Originally Posted by *CJO* /forum/post/16608055
> 
> 
> LOL- that's actually what I was thinking of when I asked since I didn't like the coarse weave of the 701
> 
> 
> 
> 
> 
> 
> 
> Maybe it's just because the sample is so small that it doesn't look good to me.
> 
> 
> CJ



I've had more than one client reject GOM FR701 for the same reason as you.










- Terry


----------



## KERMIE

My neighbor has 3 boxes of these from his remodel that he will sell me for $30.00 total. I think there is about 30 (2 x 4) tiles.


If i strip the white covering off they leave about 3/4 inch of fiberglass. I was wondering if I double them up to 1.5 inch if the will serve the same purpose to treat the bottom half of my walls or front wall if I triple stack them?


----------



## Dennis Erskine

Actually ... remove the backing on one tile only.


Your layers would be fiberglass, vinyl, fiberglass.


----------



## funlvr1965

Dennis I am assuming that he should follow the same advice that was given to me here by known audio engineers which is to NOT treat the bottom half of the wall around the room because it makes the room sound too dead. Where did all of this get started from anyway, I read it all the time where people want to treat the bottom half of the rooms up to ear level and batting above ear level only to be told that thats incorrect. For something to be so accepted on such a widespread level someone of some assumed authority on the matter must have dictated it to be so.


----------



## Dennis Erskine

I know exactly where that came from. Among the effects of that is to reduce overall reverberation time of the space while not killing the reflections which create envelopment and width of the sound stage. Now, if you want to get into diffusion, we have a different animal. The real challenging part here is to come up with a "rule" which works in all rooms ... and there ain't no such animal. Treating the bottom portion of the room doesn't, of itself, make the room too dead. It depends on (1) what you treat the bottom of the walls with and (b) what did you do to the rest of the walls?


This is also a geometry lesson ... what's the height of the speakers with respect to the ears and room treatments (these are small rooms ... geometry becomes seriously important.


----------



## KERMIE

I have a relatively small room at 12 x 18 and I would think you would want it more "dead" then not. The top half of the wall will be treated at first reflection points that I will have to determine when I get that far. My tweater height after stage is built will be roughly 40-41" on a stage.


Dennis, does leaving the vinyl on (sandwiched) help to not deaden the room as much?


----------



## Dennis Erskine

It lowers the frequencies the absorber will be effective on.


----------



## fab5valentine

Hi I'm new to this thread and I have a small project that I'd like to do right.


I have a pass through above my media center, and it passes thru to a den type room behind it. The base of the pass thru is a 10" sophet shelf that is about 3' deep to the other room. I'd like to seal this space until the time I can afford to build a new media wall. the 3' depth I'd like to split as to make a pot shelf onthe other side for the wifes things. I only need enough space for the center channel to reside. The opening is 11' W x 3' H.


Is there a link to a thread to show me the best way to do this, framing, insulation, sheet rock, glues or adhesives, absorbtion material etc.. The room is an open floor plan opening to a nook, kitchen and entry hall.. I'd like to keep it very simple as the media cenetr that holds the TV and the speakers R/L is solid and broken up fairly well with open storeage of DVD and AV equipment. My plan was to frame it, R13 insulation, sheet rock (maybe two layer on theater side), but didn't decide on finishing..


Any advice? Thanks..


-fab5valentine


----------



## R Harkness

I'm still trying to make sure that the idea of leaving our screen wall unfinished (not drywalled) and filling it with acoustic absorption material will be "to Code" in my area.


If it's not: What if I fill the wall with Roxul or OC 73 or whatever, and then drywall over it? Will this entirely negate the effects of the Roxul/OC 73 for absorbing bass frequencies?


While I'm at it: I've also got a drop ceiling of about 6" depth. It will be covered in stretched felt fabric (which has some acoustic transparency; I can blow through it).

Ideally I don't want the whole thing filled with absorption because I don't want a dead sounding room. So I like the idea of putting some diffusion up there. But if the diffusion (e.g. wood slats or some commercial diffusion panels) ends up beneath the felt ceiling material, does that defeat the diffusion effects? Or will the diffusion still occur even with the diffusers placed behind the felt?


Gotta make my decision within one or two days...


Thanks.


----------



## met64

Hey Guys; My HT room is "acoustically challenged" the bass is relatively flat and the overall sound is just too punchy... the highs are too high and I can do a simple "clap"test and it echoes. I have done e/thing in terms of processor settings- sub and audusey; in the end it is my room. The pics show (hopefully) my front stage... it is the Aperion 6T's... please notice my screen is mounted on the wall and to either side of the screen are cutouts.. directly below screen is my center and sub are both behind the wall (cutouts). The room itself is 13 wide by 19 deep- so space is at a premium. I was thinking acoustic panels at the reflection points and possibly Tri Traps behind my towers... so; am I missing anything here? I am confused by ALL the choices in terms of acoustics and given the cost of these things I want to do it right. I appreciate any ideas or feedback. Thxs in advance! Apologize for my camera skills- hopefully the pics show ok.


----------



## erkq

How important is it that I put a bass trap in a corner as a triangle? I can do that. But my projection booth extends out into the theater by 1 foot, creating a 5' by 1' alcove between it and the rear sidewall that I could completely fill with OC 703. Would this be more effective than a triangular trap?


----------



## R Harkness

Folks,


As mentioned I'm having my dropped ceiling covered in felt fabric. I have about 6" depth in which to place possible acoustic material. But I don't want to just fill it with absorption (over-damp). So I'm curious if some diffusion products will do any good if placed on the ceiling, behind the felt. I found these, *MiniFusor Sound Diffusor* from auralex:

http://www.auralex.com/sound_diffuso..._minifusor.asp 


If I put a bunch on the ceiling behind the felt, would they still be of any use in doing some diffusion to help the room?


Thanks,


----------



## nathan_h




> Quote:
> Originally Posted by *erkq* /forum/post/16628334
> 
> 
> How important is it that I put a bass trap in a corner as a triangle? I can do that. But my projection booth extends out into the theater by 1 foot, creating a 5' by 1' alcove between it and the rear sidewall that I could completely fill with OC 703. Would this be more effective than a triangular trap?



I don't know about "more effective" but yes it would be effective.


----------



## nathan_h




> Quote:
> Originally Posted by *R Harkness* /forum/post/16628719
> 
> 
> Folks,
> 
> 
> As mentioned I'm having my dropped ceiling covered in felt fabric. I have about 6" depth in which to place possible acoustic material. But I don't want to just fill it with absorption (over-damp). So I'm curious if some diffusion products will do any good if placed on the ceiling, behind the felt. I found these, *MiniFusor Sound Diffusor* from auralex:
> 
> http://www.auralex.com/sound_diffuso..._minifusor.asp
> 
> 
> If I put a bunch on the ceiling behind the felt, would they still be of any use in doing some diffusion to help the room?
> 
> 
> Thanks,



Can you blow through (breath through) the felt? If so, chances are good the high frequency sound can get through, and diffusion behind will be helpful, depending on the location and amount and the room.


I'm not sure whether the auralex product is the best one.


It has always impressed me that diffusion products are so much more expensive than absorption products, and that there is so much less scientific data about which are the most effective, and that there are so few DIY approaches.


----------



## Terry Montlick

Be careful when covering a diffuser with fabric. If it is a Schroeder type diffuser (anything which has fixed or variable well depths and flat, non-angled surfaces), you may have a problem. Such diffusers are very sensitive to restrictions in air flow near their front surface. Give them some depth (at least a few inches) behind fabric. Even very acoustically transparent fabric can add enough acoustical resistivity to make them less effective.


With old-fashioned curved diffusers (like the Auralex MiniFusor), there are no issues.


- Terry


----------



## Taz1

Guys,


I bought the JM 800MF (48"X120") duct boards and one side has the matt black finish. It almost feels like fabric and the other side has the aluminum finish. Am I able to keep just the matt black with out loosing the absorptive properities? I will be making the 24" X48" panels and use the rest for the front wall.


In the pic you can see front of one board and the back of the other board.











Thanks Tas


----------



## R Harkness

Nathan and Terry, thank you very much!


Rich


----------



## giomania




> Quote:
> Originally Posted by *giomania* /forum/post/16597246
> 
> 
> Thanks Terry.
> 
> 
> So, to apply this to my original question, would it be OK to "butt" the front wall absorption panels 2" JM 814 right up to the edge of my 34-inch face SSC corner traps, which will also be made from JM 814?
> 
> 
> Mark





> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16597382
> 
> 
> By abutting two pieces of JM 814 against each other, you will not get an edge effect from either at this common edge. If you left a gap between them, it would have to be roughly comparable in size to the wavelengths involved. So the performance of both absorbers will be reduced a bit compared to ones which have a good distance between them.
> 
> 
> - Terry





> Quote:
> Originally Posted by *pepar* /forum/post/16597878
> 
> 
> Hi, Terry. Does the edge effect have an effect on absorption of LF? And the effect that it does have (on any absorber), is it absorptive or diffusive? I ask this because of your use of the word "diffraction."





> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16598046
> 
> 
> Yes, pepar. The edge effect occurs when the dimensions of an absorbent surface become as small as (or smaller than) a wavelength.
> 
> 
> It is absorptive. Diffraction in this case refers to the bending of waves toward the absorber. This bending causes the absorber to "capture" extra waves which would otherwise not be in its geometric path. More sound is absorbed near the edges as compared with any other part of the absorber.
> 
> 
> - Terry



Terry,


Would you please tell me how far the gap between the edge of the 34-inch face SSC corner traps made with JM814 and the 2" JM 814 panels covering the remainder of the front wall should be?


Thanks.


Mark


----------



## Terry Montlick




> Quote:
> Originally Posted by *giomania* /forum/post/16630702
> 
> 
> Terry,
> 
> 
> Would you please tell me how far the gap between the edge of the 34-inch face SSC corner traps made with JM814 and the 2" JM 814 panels covering the remainder of the front wall should be?
> 
> 
> Thanks.
> 
> 
> Mark



For optimal performance, the gap _should_ be on the order of the width of an absorber. But this does not seem to be possible in your situation. So you might as well just abut them. I don't think adding a couple of inches would make a difference.


Note that the absorbers will still work just fine. They just won't be "all that they can be."










- Terry


----------



## erkq




> Quote:
> Originally Posted by *erkq* /forum/post/16628334
> 
> 
> How important is it that I put a bass trap in a corner as a triangle? I can do that. But my projection booth extends out into the theater by 1 foot, creating a 5' by 1' alcove between it and the rear sidewall that I could completely fill with OC 703. Would this be more effective than a triangular trap?



Thanks for answering Nathan. But let me ask this another way. Would a 2' wide triangular corner bass trap be less effective than filling the 5' by 1' alcove? Which should I do?


----------



## nathan_h




> Quote:
> Originally Posted by *erkq* /forum/post/16631239
> 
> 
> Thanks for answering Nathan. But let me ask this another way. Would a 2' wide triangular corner bass trap be less effective than filling the 5' by 1' alcove? Which should I do?



Sorry, the math to compare the two is way beyond me.


I know that either of your options would be beneficial.


And I know that doing both TOGETHER would be even better. So if you have that option, I recommend doing both.


----------



## pepar

Terry, is there any edge effect on a triangular SSC-style bass trap?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16636053
> 
> 
> Terry, is there any edge effect on a triangular SSC-style bass trap?



Sure. That is what likely makes a big corner absorber so good in the 80-100 Hz range:










Link: http://forum.studiotips.com/viewtopic.php?f=8&t=536 


It's not any kind of panel or membrane resonance, because these bass traps don't have any such coverings.


I've never seen a mathematical analysis of a corner bass trap. This is on my "to do" list -- for 2020.










- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16636363
> 
> 
> Sure. That is what likely makes a big corner absorber so good in the 80-100 Hz range



I only ask because there does not seem to be an edge, per se. The edges that are there taper effectively to zero.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16637091
> 
> 
> I only ask because there does not seem to be an edge, per se. The edges that are there taper effectively to zero.



Ah. You see, the edges are at the boundary between absorber and the perpendicular hard wall surfaces. The fact that they have no thickness (no exposed sides) doesn't matter. The "pure" edge effect does not depend at all on having the sides of the absorber exposed. It is a wave diffraction effect created by the sudden impedance change between absorber and wall.


- Terry


----------



## erkq




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16637321
> 
> 
> Ah. You see, the edges are at the boundary between absorber and the perpendicular hard wall surfaces. The fact that they have no thickness (no exposed sides) doesn't matter. The "pure" edge effect does not depend at all on having the sides of the absorber exposed. It is a wave diffraction effect created by the sudden impedance change between absorber and wall.
> 
> 
> - Terry



I've read that the corner absorber is more effective in some way if suspended out about 4" from the wall. I guess that's changing the boundary characteristics somehow.


----------



## giomania




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16631205
> 
> 
> For optimal performance, the gap _should_ be on the order of the width of an absorber. But this does not seem to be possible in your situation. So you might as well just abut them. I don't think adding a couple of inches would make a difference.
> 
> 
> Note that the absorbers will still work just fine. They just won't be "all that they can be."
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> - Terry



Terry,


I have 20 feet across the front wall, so I have the space. However, you guys always say to cover the entire front wall with absorption. I guess the question is, what is the lesser compromise?


Thanks.


Mark


----------



## Terry Montlick




> Quote:
> Originally Posted by *giomania* /forum/post/16639210
> 
> 
> Terry,
> 
> 
> I have 20 feet across the front wall, so I have the space. However, you guys always say to cover the entire front wall with absorption. I guess the question is, what is the lesser compromise?
> 
> 
> Thanks.
> 
> 
> Mark



Sorry Mark, I misunderstood. End your front wall absorption about one corner absorber width (2-3 feet) before the edge of each of the front corner absorbers.


- Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *erkq* /forum/post/16638561
> 
> 
> I've read that the corner absorber is more effective in some way if suspended out about 4" from the wall. I guess that's changing the boundary characteristics somehow.



I've never heard of this.


----------



## Electric_Haggis

Hi all.


I have a quick and very urgent question.
*If you click on my signature below, you'll see pictures of my room, which has double brick rendered walls.*


It's a funny shaped room. Its front and rear walls aren't perpendicular. But on average, there's 4 metres between them, and a glass door on the right which leads to the balcony.

The main listening area is about 3.7 metres wide, with an adjacent entrance to the front door & kitchen adding another 2.5 metres.


The neighbour's apartment is right on the other side of the projection screen wall.


Behind the pull-down projector screen and curtains, I've stashed a jigsaw puzzle of packing foam and styrofoam against the wall.

This serves 2 purposes...

1. It helps to reduce sound transmission to the next apartment (most importantly).

2. It helps to deaden the room a little more.


(Beneath the screen, I'm using a black carpet-like material called Wonderwall, which is tacked onto the foam. This will remain.)



But now, I'm needing to replace the foam with something else.


As you can see, there's only so much I can do.

* For one thing, it's a rented unit. So I can really only tape some sort of material against the wall.

* Ideally, I just want to gaffer tape the material to the underside of the projector screen headbox and let it hang over the wall.

* On either side of the curtained area, I'm wanting to leave that area uncovered. So sound will always transmit unimpeded.

* I have no more than 5 cms behind the screen


After looking into a few materials, I bought 7 square metres of this stuff..

POLYROLL 32/25 BLACK, a third of the way down the list...
http://www.peaceandquiet.com.au/price_list.htm 



Now, holding up some of this Pollyroll material against a speaker, I notice that it's blocking relatively little sound from coming through, compared to styrofoam, cardboard, etc.


I'm wondering if I should swap it for something more like this barrier material...
http://www.peaceandquiet.com.au/NOISEBAR_BASE_PQ.pdf 

...although I was advised that absorbtion on my side would be the best way to stop sound transmission.

A barrier material would be mostly useless as the sound will get in on either side anyway?




What's the best possible (and most cost-effective) material that I could use in this case?

As it's concealed, colour and ugliness are non-issues.



Two other points:

* The left/right main speakers have front & rear bass ports, and go down to around 25Hz.

* I have a slight bass boom problem, which I'll be helping to alleviate by making some bass traps for the corners.




Thank you very much, in advance!


----------



## Terry Montlick




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16640700
> 
> 
> ...
> 
> I'm wondering if I should swap it for something more like this barrier material...
> http://www.peaceandquiet.com.au/NOISEBAR_BASE_PQ.pdf
> 
> ...although I was advised that absorbtion on my side would be the best way to stop sound transmission.



Yes, the heaviest of these materials would help some, but it is a rather expensive option. You need mass. Whoever told you that sound absorptive material would stop sound transmission is basically wrong.


A good cheap type of massive material is interior drywall. Unfortunately, you won't be able to just tape it up. But that's true of the NoiseBarBase stuff as well.











> Quote:
> A barrier material would be mostly useless as the sound will get in on either side anyway?



Which is why you would need to thoroughly and seamlessly cover adjacent "flanking paths" as well.


- Terry


----------



## Electric_Haggis

Thanks Terry. Love your work, by the way.



It sounds like I'd be better off paying a few dollars more and swapping the Pollyroll material with the 4kg Noisebar, right?


Unless I'm able to completely cover and seal the wall with the material, it's always going to be a semi-lost cause. But is it still fair to say that a barrier material like the Noisebar will make more of a difference on the other side, while having a similar effect in deadening my room?


Like I said, simply holding up the material over a loudspeaker made me question the effect of the Pollyroll. It's effectively useless at blocking sound.

The packing foam I used previously seemed to transmit noticeably less, and I imagine its absorbtion properties wouldn't be too bad either(?)


As you can see from my pics, I could use a thumping good bass trap or two - especially in the front right corner!


Is it fair to say that less sound will be transmitted if more of it is being absorbed on my side, whatever the frequency?

When I put in some bass traps, and succeed in reducing booming, summing and standing wave issues on my side, then there'll simply be _less_ of that bloated bass to escape, correct?


----------



## Terry Montlick

Hi Haggis,


> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16644564
> 
> 
> It sounds like I'd be better off paying a few dollars more and swapping the Pollyroll material with the 4kg Noisebar, right?



Yes. But as I said, this is a heavy material, so be prepared to use some really strong tape around the edges to hold it -- duct tape or gaffer's tape. And you can use anything else which comes in sheets and is heavy.



> Quote:
> Is it fair to say that less sound will be transmitted if more of it is being absorbed on my side, whatever the frequency?
> 
> When I put in some bass traps, and succeed in reducing booming, summing and standing wave issues on my side, then there'll simply be _less_ of that bloated bass to escape, correct?



'Fraid not. This is a case of what seems obvious and intuitively correct doesn't really work when you look at the numbers.


Lets consider a typical low frequency, like 125 Hz. This is low enough to be readily treatable by bass traps. It's not even into the subwoofer frequency range, but it can still be annoying as hell when it comes through your neighbor's wall.


Typical single-stud residential walls have a transmission loss of around 10 dB at 125 Hz. That means than if you play a 125 Hz sound at 75 dB (a reasonable volume) in your room, it will be 75-10 dB = 65 dB on the other side of the wall. This will be bothersome to someone trying to carry on a conversation, let alone sleep.


Now you put up a lot of big, aggressive bass traps, and succeed in absorbing 50% of the 125 Hz room energy. This will improve your low frequency sound quite a bit. Room modes at around 125 Hz will be noticeably quieter, and their decay times will be slashed in half.


But in terms of decibels, a 50% reduction in energy is only 3 dB. So now the 75 dB sound at 125 Hz which your neighbor hears is only reduced to 75-10-3 dB = 62 dB. This is still not quiet by any means. Compensating for the fact that we don't hear low frequences as well as mid frequencies, this translates to a Noise Criterion level of NC 50. A typical "quiet room" is about NC 30. The maximum recommended noise level in a sports coliseum is no more than NC 55. This will likely be small comfort to your neighbor.










- Terry


----------



## unclepauly




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16647101
> 
> 
> Hi Haggis,
> 
> 
> Yes. But as I said, this is a heavy material, so be prepared to use some really strong tape around the edges to hold it -- duct tape or gaffer's tape. And you can use anything else which comes in sheets and is heavy.
> 
> 
> 
> 'Fraid not. This is a case of what seems obvious and intuitively correct doesn't really work when you look at the numbers.
> 
> 
> Lets consider a typical low frequency, like 125 Hz. This is low enough to be readily treatable by bass traps. It's not even into the subwoofer frequency range, but it can still be annoying as hell when it comes through your neighbor's wall.
> 
> 
> Typical single-stud residential walls have a transmission loss of around 10 dB at 125 Hz. That means than if you play a 125 Hz sound at 75 dB (a reasonable volume) in your room, it will be 75-10 dB = 65 dB on the other side of the wall. This will be bothersome to someone trying to carry on a conversation, let alone sleep.
> 
> 
> Now you put up a lot of big, aggressive bass traps, and succeed in absorbing 50% of the 125 Hz room energy. This will improve your low frequency sound quite a bit. Room modes at around 125 Hz will be noticeably quieter, and their decay times will be slashed in half.
> 
> 
> But in terms of decibels, a 50% reduction in energy is only 3 dB. So now the 75 dB sound at 125 Hz which your neighbor hears is only reduced to 75-10-3 dB = 62 dB. This is still not quiet by any means. Compensating for the fact that we don't hear low frequences as well as mid frequencies, this translates to a Noise Criterion level of NC 50. A typical "quiet room" is about NC 30. The maximum recommended noise level in a sports coliseum is no more than NC 55. This will likely be small comfort to your neighbor.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> - Terry



So.... a 100% reduction in energy is only 6 db? Or is there some curve I don't know about. Admittedly I'm very new to this.


----------



## Electric_Haggis

Cheers again.


My walls are all rendered brick, with double-brick separating me from the next unit. Not sure how that measures against plaster/gyprock/stud walls ?


I got a call back from another material supplier today.

By all accounts, it sounds like I'm either better off just keeping the 32kg/25mm (NRC- 0.55) Pollyroll material I've got and adding another layer of the same... or better still, a layer of 4kg loaded vinyl between the Pollyroll and the wall?


By the way, is anyone familiar with Audimute? I'm not in the US, but it's woth bearing in mind...
http://www.audimutesoundproofing.com...-blankets.aspx 



But by far, it seems the biggest transmission yields will come from bass traps.


I'm thinking of making two stacks of _Toblerone_-shaped traps for the front left and front right corners. (Again, my signature will take you to the pics).

They'd be 850 to 1000mm wide, and go from the floor to the ceiling, which is 2400mm.

I was looking at this material (minus the foil), which is available in thicknesses of...

50mm (NRC - 0.9)

75mm (NRC - 1.05)

100mm (NRC - 1.1)

All are 48kg per cubic metre...
http://www.acoustica.com.au/hdbatts.html 


At least for now, I was thinking of just cutting up the 75mm or 100mm batts, putting them diagonally into the corners and leaving out the frames and fabric for the time being.


I might also hang a 50mm slab on the back wall behind the listening position, at least 1000mm wide and 500mm high.


I want to stay away from fibreglass. Are these batts a good material, or can I do better without breaking the bank?


----------



## Elill




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16652306
> 
> 
> I was looking at this material (minus the foil), which is available in thicknesses of...
> 
> 50mm (NRC - 0.9)
> 
> 75mm (NRC - 1.05)
> 
> 100mm (NRC - 1.1)
> 
> All are 48kg per cubic metre...
> http://www.acoustica.com.au/hdbatts.html



Check out Ultratel or Supertel by CSR - you'd have to call a CSR place for them to give you a supplier, where'd you live? It's not cheap though, about $350 per bag. You want to look at the absorption across the board i.e. frequency spectrum - not just the overall NRC. I think? I assume your more concerned about lower frequency issues?


See:

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Electric_Haggis

I am. I'm actually very happy with the room's mid-high performance, although I see no reason not to improve it as far as is monetarily possible, without destroying the room.

Bass boom is the *big* issue, in both the absorption and transmission departments.


The CSR suggestion looks great, if pricey.

Another issue is that I'm in... Sydney, Australia! This puts paid to quite a few options, methinks.


Doing what I should perhaps have done in the first place - looking for the most ideal product from the cheapest specialist suppliers - I've come up with these materials...

Dense (no more than 50mm), absorbent material for behind the screen/curtains with reasonable transmission properties...
http://www.thefoambooth.com.au/front...uctID=Acc50/25 

... no need to tape it to the wall or headbox, either.

Bass Traps for the front corners. (Convoluted face)

Two of these for each corner will fit snuggly from floor to ceiling, require no fixtures, and be ready to go...
http://www.acousticalsolutions.com/p...lphacorner.asp 

... As I'm metering out the budget, I might start with two and add two later.


Acoustic panel for the rear wall...
http://www.acousticalsolutions.com/p.../Anchorage.asp 

I'll leave this one till last, using some leftover Sonex-like material in the meantime, and may even build my own in the end.


_Are these materials good bang for buck, compared to similarly priced alternatives?_

(Again, click on my signature to see the room.)


Thanks again...


----------



## Elill

I should have said I live in Sydney too...it took me ages to find a suitble product...not that I've used it yet. But there are a few other Aussies here that use Ultratel...cant buy it from Bunnings though. There are specialist providers - call CSR directly and ask for a local supplier. I know there is one in Castle Hill - Sydney insulation or something. Trust me, you wont find it via google


----------



## Weasel9992




> Quote:
> Originally Posted by *unclepauly* /forum/post/16652024
> 
> 
> So.... a 100% reduction in energy is only 6 db? Or is there some curve I don't know about. Admittedly I'm very new to this.



That's correct, but that's not the same thing as 100% reduction in _transmission_ of course.


Frank


----------



## Terry Montlick

No!!!!!









A decibel is defined as 10 time the log (base 10) of the power ratio.


So a 50% power ratio (50% reduction) = -3dB.

A 25% power ratio (75% reduction) = -6 dB.

A 10% power ratio (90% reduction) = -10 dB.

A 0% power ratio (100% reduction) = -infinity dB.

Etc.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16653332
> 
> 
> No!!!!!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> A decibel is defined as 10 time the log (base 10) of the power ratio.
> 
> 
> So a 50% power ratio (50% reduction) = -3dB.
> 
> A 25% power ratio (75% reduction) = -6 dB.
> 
> A 10% power ratio (90% reduction) = -10 dB.
> 
> A 0% power ratio (100% reduction) = -infinity dB.
> 
> Etc.



Terry,


I'm not following this. Probably because I don't know what is meant by "power ratio". A little help please?


----------



## erkq




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/16654088
> 
> 
> Terry,
> 
> 
> I'm not following this. Probably because I don't know what is meant by "power ratio". A little help please?



A change in db is a ratio at any power level. So, for instance, if you have 100 watts and reduce it to 50 watts, that 50% reduction in power is a 3 db difference. Going from 10 watts to 5 watts is also a 3 db difference. So you have to look at the 3 db change in logarithmic land (db) as a power ratio in linear land (watts/volts/spl/whatever).


Did I add mud to the waters?


----------



## KNKKNK

Hello all,


I have a couple of questions reguarding diffusion.


Below is a picture of "Wooden Cube" Ceiling inserts

The Cubes are 1 1/2 or 2 1/4" deep, and come in sizes of 1/4, 1/2, and 3/4" thick blades











Im looking at using the 2' x 2' "Wooden Cube" panels as the center insets in a 4' x 4' coffered ceiling design. I would end up with 9 of these panels in my ceiling (18.5 x 16.5 room).


So the question is : will these panels offer diffusion benefits.


Second part of the question: Their seems to be a school of thought that Diffusion need to be a min of 10' from the listener.. (if i understand what i have read). Is this an accurate interpretation? If so,, this seems like it would be a deal breaker for diffusion in a lot of rooms, unless placed on the ceiling in the front or rear of the room only. Assuming you would get diffusioin from these panels, would it be detremental to place directly over the listeneing position?


Any feedback would be appreciated.


Thanks

Brad


----------



## Terry Montlick




> Quote:
> Originally Posted by *KNKKNK* /forum/post/16654290
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ..
> 
> So the question is : will these panels offer diffusion benefits.



No. These will not diffuse sound.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *erkq* /forum/post/16654264
> 
> 
> A change in db is a ratio at any power level. So, for instance, if you have 100 watts and reduce it to 50 watts, that 50% reduction in power is a 3 db difference. Going from 10 watts to 5 watts is also a 3 db difference. So you have to look at the 3 db change in logarithmic land (db) as a power ratio in linear land (watts/volts/spl/whatever).
> 
> 
> Did I add mud to the waters?



No mud added. Actually, that last bit "(watts/volts/spl/whatever)" answered my question.


Thanks!


----------



## Electric_Haggis

Can anyone offer their views on the materials I've listed above?


Thanks again.


----------



## nathan_h




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16656918
> 
> 
> Can anyone offer their views on the materials I've listed above?
> 
> 
> Thanks again.



Fiberglass or rockwool will outperform foam, esp for bass trapping.


I don't know what vendors might be accessible in Australia, but I assume shipping from the US would be excessive.


I'm not clear how DIY handy you are, or what aesthetic criteria you have, but something like the corner traps that REALTRAPS sells or like the pedestal or corner traps that GIK ACOUSTIC sells would likely be worth imitating, if you are going to build something yourself.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/16658450
> 
> 
> Fiberglass or rockwool will outperform foam, esp for bass trapping.
> 
> 
> I don't know what vendors might be accessible in Australia, but I assume shipping from the US would be excessive.
> 
> 
> I'm not clear how DIY handy you are, or what aesthetic criteria you have, but something like the corner traps that REALTRAPS sells or like the pedestal or corner traps that GIK ACOUSTIC sells would likely be worth imitating, if you are going to build something yourself.



Well, if they have heating, ventilation and air conditioning in Australia, then they have companies selling the fiberglass we are talking about here.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *nathan_h* /forum/post/16658450
> 
> 
> Fiberglass or rockwool will outperform foam, esp for bass trapping.
> 
> 
> I don't know what vendors might be accessible in Australia, but I assume shipping from the US would be excessive.
> 
> 
> I'm not clear how DIY handy you are, or what aesthetic criteria you have, but something like the corner traps that REALTRAPS sells or like the pedestal or corner traps that GIK ACOUSTIC sells would likely be worth imitating, if you are going to build something yourself.



Well for now, ready-made foam bass traps like the ones above are appealing on many levels. Apart from not having to build them or fix them to the walls, I could simply buy 2 and comfortably wedge them from floor to ceiling.


I'm sure rockwool, fibreglass or glasswool would perform better for bass, although I'm not sure how much (?)


Following Elil's suggestion , I may use this glasswool material for the 3m x 2.2 x 50mm metre area behind the screen/curtains/speakers...
http://www.bradfordinsulation.com.au.../Ultratel.aspx 


It's very dense, quite rigid it should absorb bass nicely, it's quite cheap $30ish for a square metre, and comes two packs of 1500x2400 will do the job.


----------



## nathan_h

Yes, glasswool. That's what you want.


Trying to quantify how much better it is than foam, let's say that for the same size, glasswool is twice as useful for bass trapping.


You could use that Bobgold link mentioned above to the exact figure.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *nathan_h* /forum/post/16658681
> 
> 
> Yes, glasswool. That's what you want.
> 
> 
> Trying to quantify how much better it is than foam, let's say that for the same size, glasswool is twice as useful for bass trapping.
> 
> 
> You could use that Bobgold link mentioned above to the exact figure.



A material like this would seem to be the best of all......?
* http://www.acoustica.com.au/hdbatts.html *



It seems ideal...

* Polyester, so no flaking

* 48kg/m3 density

* I heard somewhere that polyester has a more consistant density than Rockwool (?)

* Available in 50mm, 75mm and 100mm thicknesses

* White

* Two (or more if layered) 1200 x 600 batts would make a floor-to-ceiling bass trap.

* Available with foil backing

* Pretty cheap - around AU$15 a square metre


What do we think of this compared to the alternatives?


----------



## nathan_h

Double up the 100mm batts, and lay that across some corners, and that would likely work well. I didn't do the math, but it does seem like it would work. However, one of the things DIYers like is the semi/rigid nature of the popular Owens Corning stuff that everyone in the US uses. I get the impression that product you reference is not rigid, so that's a lot of work to turn it into panels.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *nathan_h* /forum/post/16665957
> 
> 
> Double up the 100mm batts, and lay that across some corners, and that would likely work well. I didn't do the math, but it does seem like it would work. However, one of the things DIYers like is the semi/rigid nature of the popular Owens Corning stuff that everyone in the US uses. I get the impression that product you reference is not rigid, so that's a lot of work to turn it into panels.




True. I'll see how rigid it is (or isn't) when I go to have a look at the stuff.

The foil backing would help, though.


Acording to the link, it's available in weights of up to 180kg/m3 ! That would be somewhat rigid, methinks!!!
http://www.acoustica.com.au/hdbatts.html 


For the record, I've also found a very dense (and probably rigid) rockwool batt...
http://www.bradfordinsulation.com.au...uct-liner.aspx 



I'm still learning about the wonderful world of traps, but there's an excellent How-to by the _legendary_ Ethan Winer here...
http://www.ethanwiner.com/basstrap.html 


He speaks of using a plywood front face for extra effect. One could loosley bond a couple of layers together, and then on to a 2400 high sheet of thin plywood, perhaps with a base plate for a bit of weight at the bottom.


Making a 2400mm high pinewood frame is pretty easy, especially as it comes in that length.


Another option would be to cut a series of triangles and just pile them up - with or without a frame or front face.

In a way, this may be best for me as my front corners are actually more like 110 and 70 degrees, and on the right side, I'd rather have a broader 900mm wide trap anyway.

(Again, click my signature for pics.)


----------



## Weasel9992




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16665769
> 
> 
> It seems ideal...
> 
> * Polyester, so no flaking
> 
> * 48kg/m3 density
> 
> * I heard somewhere that polyester has a more consistant density than Rockwool (?)
> 
> * Available in 50mm, 75mm and 100mm thicknesses
> 
> * White
> 
> * Two (or more if layered) 1200 x 600 batts would make a floor-to-ceiling bass trap.
> 
> * Available with foil backing
> 
> * Pretty cheap - around AU$15 a square metre




It'll work fine. You can even leave the foil on it for the corner bass traps or the bass traps behind your head (depending on how far away from your head they are). Make sure you take the foil off for the panels at the first reflection points though.


Frank


----------



## Elill




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16667566
> 
> 
> It'll work fine



Are the properties of polyester as good for bass trapping as fibre glass even if they have the same density? Also will it work as well for reflection points?


Happy days if it is, this'll save me quite a bit of coin (about 1/3 of the cost).


----------



## Terry Montlick




> Quote:
> Originally Posted by *Elill* /forum/post/16671956
> 
> 
> Are the properties of polyester as good for bass trapping as fibre glass even if they have the same density? Also will it work as well for reflection points?
> 
> 
> Happy days if it is, this'll save me quite a bit of coin (about 1/3 of the cost).



Yes. Though it is hard to find polyester fiber material as dense as semi-rigid fiberglass. I've never seen it in the US.


- Terry


----------



## Electric_Haggis




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16672462
> 
> 
> Yes. Though it is hard to find polyester fiber material as dense as semi-rigid fiberglass. I've never seen it in the US.
> 
> 
> - Terry



Sounds like a 48kg/m3 100mm polyester batt will not be quite as rigid as a 48kg/m3 100mm fibreglass, although its absorbtion prooperties are very similar?


At any rate, that polyester above comes in densities of up to 180kg/m3.

I imagine for the same thickness, that would be pretty rigid, especially with a backing.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16672496
> 
> 
> Sounds like a 48kg/m3 100mm polyester batt will not be quite as rigid as a 48kg/m3 100mm fibreglass, although its absorbtion prooperties are very similar?



Rigidity actually has nothing to do with acoustic absorption. Since you are in Australia, you are all set! I'd go with the 48kg/m3 polyester batts. They should give performance comparable to Owens Corning 703 (3 pcf) fiberglass.


In the US, we are very fiberglass-based. Owens Corning, a big US company, invented the stuff.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16672669
> 
> 
> Rigidity actually has nothing to do with acoustic absorption. Since you are in Australia, you are all set! I'd go with the 48kg/m3 polyester batts. They should give performance comparable to Owens Corning 703 (3 pcf) fiberglass.




OK, so density is really the determining factor.


However, if you take two 75mm thick batts, one at 48kg/m3 and the other at 180kg, the 180kg will always provide more absorbtion, yes?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16672744
> 
> 
> OK, so density is really the determining factor.
> 
> 
> However, if you take two 75mm thick batts, one at 48kg/m3 and the other at 180kg, the 180kg will always provide more absorbtion, yes?



No.










It's not that simple. Too much thickness of too dense a material (a material with a high acoustic resistivity) may reflect and therefore not absorb high frequencies as well as less thick and dense materials.


And to make matters more complicated, acoustic resistivity does not increase linearly with density. That is, doubling the density does not in general double the resistivity. It is a more complex relationship which is material-specific.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16672774
> 
> 
> No.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It's not that simple. Too much thickness of too dense a material (a material with a high acoustic resistivity) may reflect and therefore not absorb high frequencies as well as less thick and dense materials.
> 
> 
> And to make matters more complicated, acoustic resistivity does not increase linearly with density. That is, doubling the density does not in general double the resistivity. It is a more complex relationship which is material-specific.



Okey dokey, then.


Well the first thing I want to do is to make a 2400mm-high, floor-to-ceiling corner trap for the front right.

I want to make it 900mm wide (so it'll go from the curtain at the front to the curtain at the side wall. Again, click my signature.)



I could either....


1. Stack up a series of triangles to make a Toblerone shape


or


2. Make a pinewood frame and add one or two layers (?) of 75mm (?) 48kg/m3 polyester batts.


Other additions, like material and perhaps plywood (?), would follow shortly after.


Any thoughts on the above?

Reducing bass boom is the goal. No great desire to affect the higher frequencies.


Thanks!


----------



## Terry Montlick




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16673283
> 
> 
> Okey dokey, then.
> 
> 
> Well the first thing I want to do is to make a 2400mm-high, floor-to-ceiling corner trap for the front right.
> 
> I want to make it 900mm wide (so it'll go from the curtain at the front to the curtain at the side wall. Again, click my signature.)
> 
> 
> 
> I could either....
> 
> 
> 1. Stack up a series of triangles to make a Toblerone shape
> 
> 
> or
> 
> 
> 2. Make a pinewood frame and add one or two layers (?) of 75mm (?) 48kg/m3 polyester batts.



Go for the Toblerone.


----------



## Weasel9992




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16674281
> 
> 
> Go for the Toblerone.



Mmmmmmm...Toblerone.


Frank


----------



## Electric_Haggis




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16674281
> 
> 
> Go for the Toblerone.



mmmmmmmm... Toblerone it is.



May as well ask....


50mm / 75mm thick, 48kg/m3 batts with no foil backing are the cheapest.


But 100mm thickness is also available, and densities of up to 180kg/m3.


Is it worth my while getting anything more than 75mm / 48kg ?


----------



## nathan_h

Terry was serious, I think; Frank was making a joke but essentially agreeing.


I'm actually thinking about some DIY diffusion for my front wall (under the screen) and perhaps the side wall and/or ceiling. (I'm using some GIK panels under the screen, but might move the to the ceiling -- or a corner for more bass trapping.)


Would a simple shape, repeated, like the triangle chocolate's box really work well? How big should the triangle be? For example, I could get a bunch of 2x2s and rip them in half the long ways, and glue them to thin plywood or luon.


Previously I was thinking I had to get mathematical and fancy. But maybe I was just over complicating things.


----------



## Terry Montlick




> Quote:
> Originally Posted by *nathan_h* /forum/post/16677810
> 
> 
> Would a simple shape, repeated, like the triangle chocolate's box really work well? How big should the triangle be?



Did you look at the Studiotips SuperChunk corner absorbers I referenced earlier? If not, here's a link:

http://forum.studiotips.com/viewtopic.php?f=8&t=535 


They are easy to make, and work great.


- Terry


----------



## nathan_h

My mistake. I was speaking of a small triangular shaped ridges spaced close together to create a diffuser, not a large trap.


Something that would be far more DIY easy than something like this:











For an application like this:











though I am more interested in the front wall, side walls and ceiling that the back wall right now.


----------



## CJO




> Quote:
> Originally Posted by *nathan_h* /forum/post/16677810
> 
> 
> I'm actually thinking about some DIY diffusion for my front wall (under the screen) and perhaps the side wall and/or ceiling. (I'm using some GIK panels under the screen, but might move the to the ceiling -- or a corner for more bass trapping.)



Why would you use diffusion on the front wall under the screen? I understand on the side walls, back walls, and ceiling, but I'm not sure what diffusion on the front wall would accomplish?


CJ


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16677976
> 
> 
> Did you look at the Studiotips SuperChunk corner absorbers I referenced earlier? If not, here's a link:
> 
> http://forum.studiotips.com/viewtopic.php?f=8&t=535
> 
> 
> They are easy to make, and work great.
> 
> 
> - Terry


 http://peparsplace.com/Pg_23.htm


----------



## nathan_h




> Quote:
> Originally Posted by *CJO* /forum/post/16678070
> 
> 
> Why would you use diffusion on the front wall under the screen? I understand on the side walls, back walls, and ceiling, but I'm not sure what diffusion on the front wall would accomplish?
> 
> 
> CJ




Seems to be one way to increase the sound stage depth, without pulling the speakers even further into the room (they are already about as far into the room as makes sense).


----------



## Terry Montlick




> Quote:
> Originally Posted by *nathan_h* /forum/post/16677810
> 
> 
> I'm actually thinking about some DIY diffusion for my front wall (under the screen) and perhaps the side wall and/or ceiling.



Sorry, I missed seeing this. DIY Schroeder diffusers (the ones with variable depth wells) are difficult for DIY construction. Alternatives are:


Slanted wedges -- good for flutter echo between parallel walls

Luan plywood bent into an arc (polycylindrical) - general purpose


The depth will depend on the frequencies you need to diffuse. Larger and deeper extend lower in frequency. I have no idea what your specific acoustical issues are, but typical diffusers are a minimum of 6" deep.


- Terry


----------



## nathan_h

Thanks for the ideas. Yes, I was intimidated by the DIY Schroeder diffuser idea.


My room is 12.5ft by 17ft by 8 ft.


I've got a pair of 4inch thick 2x4ft bass traps straddling the rear/side walls, and another pair flat against the front side walls near the corner. (The screen prevents them from straddling the corner.)


At the Left and Right first reflection points I have 2inch 2x5ft fiberglass absorbers. And I have two such panels under the screen, and two such panels on the rear wall, as well.


I'm thinking, instead of buying/making two or three panels for the ceiling, perhaps I have built a diffuser for the front wall, increasing the soundstage depth (especially on two channel music) and move the panels from there to the ceiling.


----------



## KeithR

Hey guys-


I am a two channel guy, but looking for someone to come in and do room acoustics for a mixed use room. Are there any recommended folks in Los Angeles?


I have a 24'x28'x8' room (so large), although 1/3 of it is a dining area. I know some basics about acoustics, but would prefer to bring someone in.


I have read up on ASC---but don't like the full absorption model in other rooms i've heard. Rives does stuff to, but figure since i am in LA, the king of recording studios, there might be a local guy who i would pay to come out, measure, and have a consultation.


Thanks,


KeithR


----------



## R Harkness




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16672774
> 
> 
> No.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It's not that simple. Too much thickness of too dense a material (a material with a high acoustic resistivity) may reflect and therefore not absorb high frequencies as well as less thick and dense materials.
> 
> 
> And to make matters more complicated, acoustic resistivity does not increase linearly with density. That is, doubling the density does not in general double the resistivity. It is a more complex relationship which is material-specific.



Whoa. I wonder if my plan has been wrong then (or not).


I can't get into "true" bass trapping in my room but I've been planning to do the best I can. I've been planning to do as big an aborber as I can put over the screen - 24" wide, 12 feet long, of OFI 48 (essentially like OC 703)...piled up 5" thick.


I also planned to put similar 5" thick piles in the ceiling corners.


Is this the right approach (trying to absorb as low a frequency as I can get to help with mid-bass bloat) or might I end up with reflection rather than absorption? And if I'd end up with reflection, what is the better approach?

Would I add something else in between the OFI 48 layers or something?


Thanks again.


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/16696121
> 
> 
> Whoa. I wonder if my plan has been wrong then (or not).
> 
> 
> I can't get into "true" bass trapping in my room but I've been planning to do the best I can. I've been planning to do as big an aborber as I can put over the screen - 24" wide, 12 feet long, of OFI 48 (essentially like OC 703)...piled up 5" thick.
> 
> 
> I also planned to put similar 5" thick piles in the ceiling corners.
> 
> 
> Is this the right approach (trying to absorb as low a frequency as I can get to help with mid-bass bloat) or might I end up with reflection rather than absorption? And if I'd end up with reflection, what is the better approach?
> 
> Would I add something else in between the OFI 48 layers or something?
> 
> 
> Thanks again.



This plan is just fine, Rich. First of all, since you are interested in absorbing bass, any non-absorption of high frequencies (in the kHz!) is moot. Also, 3 pcf fiberglass does not have too much density, even at 5" thick. You can go as thick as you want with it, again, assuming that you don't want a broadband absorber working efficiently up to the highest frequencies -- to place at early reflection spots, for example.


For the screen wall this is fine as well, because speakers are directional at high frequencies and simply won't generate that much sound rearward. And again, any reasonable thickness of 3 pcf fiberglass (even a foot or two) will still absorb more highs than it reflects.


- Terry


----------



## R Harkness

Whew. I sure appreciate your input Terry. Thank you!!!


----------



## Weasel9992




> Quote:
> Originally Posted by *R Harkness* /forum/post/16696121
> 
> 
> Is this the right approach (trying to absorb as low a frequency as I can get to help with mid-bass bloat) or might I end up with reflection rather than absorption? And if I'd end up with reflection, what is the better approach?
> 
> Would I add something else in between the OFI 48 layers or something?



Like Terry said, you'll be fine...definitely down into the low mids if not lower.


Frank


----------



## tleavit

Looking for some honest opinions on my sound panel setup so far:


I feel like I mounted the front reflection points a bit to high.


Please note, I'm not done, I'm just out of panels (I buy about 2 a month).


Any suggestions?


What do people think about a thick rug for the floor in front?


----------



## Kal Rubinson

Instead of the thick rug, put a panel or two on the first reflection points on the ceiling. And then stop and consider whether or how much more you really need. Have you done any measurements?


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/16730602
> 
> 
> Looking for some honest opinions on my sound panel setup so far:
> 
> 
> I feel like I mounted the front reflection points a bit to high.
> 
> 
> Please note, I'm not done, I'm just out of panels (I buy about 2 a month).
> 
> 
> Any suggestions?



I think the white/near white walls and ceiling will wash out your picture from light reflected off the screen onto them and reflected back onto the screen.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *pepar* /forum/post/16731386
> 
> 
> I think the white/near white walls and ceiling will wash out your picture from light reflected off the screen onto them and reflected back onto the screen.



Absolutely!


A dedicated room like yours should be as much of a cave as possible.

You'll be _staggered_ by the difference that dark walls make.

If you don't want to paint them, then perhaps do what I did in my previous place and put up curtains and rails for the side walls. This will noticeably help the sound, too.



Ideally, have a dark ceiling, and a dark floor rug too.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/16731386
> 
> 
> I think the white/near white walls and ceiling will wash out your picture from light reflected off the screen onto them and reflected back onto the screen.



And all those equipment lights lined up in front aren't great either. I know the equipment is on display, but who wants to see all those lights when watching a movie? Boy... we purists are really raggin' on you, aren't we?







Here's a pic of my theater. Nuthin' but screen! (The door and trim have since been dealt with.)


EDIT: You can rag on me for the white couches. I just built the house and am feeling mighty poor right now, otherwise I'd get a nice black leather set.


----------



## Weasel9992




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/16730784
> 
> 
> Instead of the thick rug, put a panel or two on the first reflection points on the ceiling. And then stop and consider whether or how much more you really need. Have you done any measurements?



I'd agree...you've got a lot on the front wall, and you should probably shift some to the reflection points. How about the back wall? What's going on back there?


Frank


----------



## tleavit




> Quote:
> Originally Posted by *pepar* /forum/post/16731386
> 
> 
> I think the white/near white walls and ceiling will wash out your picture from light reflected off the screen onto them and reflected back onto the screen.



The flash lights it up. The paint is actually a really dark gray. When the lights are out its perfectly black. The carpet is also a pretty dark gray. All trim in the room is flat black.


this picture shows it better (lights are even still on),


This picture also shows that I put sound panels on the floor in "movie mode" to hide the front lights.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/16732060
> 
> 
> And all those equipment lights lined up in front aren't great either. I know the equipment is on display, but who wants to see all those lights when watching a movie? Boy... we purists are really raggin' on you, aren't we?
> 
> 
> 
> 
> 
> 
> 
> Here's a pic of my theater. Nuthin' but screen! (The door and trim have since been dealt with.)
> 
> 
> EDIT: You can rag on me for the *white couches*. I just built the house and am feeling mighty poor right now, otherwise I'd get a nice black leather set.



I'm sure they go well with your shag rug.


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/16732878
> 
> 
> The flash lights it up. The paint is actually a really dark gray. When the lights are out its perfectly black. The carpet is also a pretty dark gray. All trim in the room is flat black.
> 
> 
> this picture shows it better (lights are even still on),
> 
> 
> This picture also shows that I put sound panels on the floor in "movie mode" to hide the front lights.



Project an image onto the screen, hit pause and take a flash-free picture. That would be a better test of your wall/ceiling color and whether or not they should be darker.


----------



## tleavit




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16732461
> 
> 
> I'd agree...you've got a lot on the front wall, and you should probably shift some to the reflection points. How about the back wall? What's going on back there?
> 
> 
> Frank




The back is the problem right now and the next focus of attention. I want to cover it pretty good. If I stand at my center speaker and "clap" I still get echo from the rear. If I move to my 5 feet over closer to the front reflection points and clap.. I don't get any echo.


Older pic of the back:











Newer


----------



## tleavit




> Quote:
> Originally Posted by *pepar* /forum/post/16732902
> 
> 
> Project an image onto the screen, hit pause and take a flash-free picture. That would be a better test of your wall/ceiling color and whether or not they should be darker.



These are the best I have. I have always found it hard to take pictures down there (Using my Sony A700 SLR) when the lights are off because the room is dead dark and the image is really bright. One of these has my 46" LCD TV in it. I used to have an LCD TV behind the screen but took it out since I wasn't using it as much as I thought I would. You can see the image reflect of the equipment under the screen.


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/16732926
> 
> 
> These are the best I have. I have always found it hard to take pictures down there (Using my Sony A700 SLR) when the lights are off because the room is dead dark and the image is really bright. One of these has my 46" LCD TV in it. I used to have an LCD TV behind the screen but took it out since I wasn't using it as much as I thought I would. You can see the image reflect of the equipment under the screen.



Yes, but not much off the walls or ceiling. Looks like you've got that under control.


----------



## tleavit

What do you think I should do with the rear? I was thinking 4 to 6 panels?


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/16732886
> 
> 
> I'm sure they go well with your shag rug.



Well! I never! It's NOT a shag rug!










I like what you do with the panels in "movie mode". That's a good solution.


----------



## R Harkness




> Quote:
> Originally Posted by *pepar* /forum/post/16732886
> 
> 
> I'm sure they go well with your shag rug.



Shag rugs have been back "in" for quite a while now! Open any "metropolitan" magazine or attend any design show and you'll see shag rugs

everywhere.


I love them and ordered one for my own HT room. My kids love it, feels awesome, looks funky-cool.


----------



## Electric_Haggis




> Quote:
> Originally Posted by *tleavit* /forum/post/16732910
> 
> 
> The back is the problem right now and the next focus of attention. I want to cover it pretty good. If I stand at my center speaker and "clap" I still get echo from the rear. If I move to my 5 feet over closer to the front reflection points and clap.. I don't get any echo.
> 
> 
> Older pic of the back:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Newer




My friend, having floorstanding towers like that aiming at the back wall, below ear level out of proper ear-shot to all except those in the back row is just wrong.


I've been there. Trust me... you can do _a lot_ better.


Consider wall-mounted bipole or dipole surrounds around half way down your seating area, and ideally another pair of bipole surrounds at the back for 7.1. That'll be a huge improvement.


The layout with your back wall is tricky, so either ceiling-mount the rears, or wall-mount them to the sides behind the seating area, or stand-mount them.


You can also have just one pair of dual-monopole surrounds (like the Infinity BETA ES250 or JBL's P52OWS ) and still go 7.1


In any case, surrounds in your room should be at least a foot above seated ear-level.


The are a couple of dipole-bipole threads here on AVS.

Some excellent speakers include Monitor Audio BFX , Paradigm's ADP surrounds and Axiom's QS8 .


----------



## tleavit




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/16744557
> 
> 
> My friend, having floorstanding towers like that aiming at the back wall, below ear level out of proper ear-shot to all except those in the back row is just wrong.
> 
> 
> I've been there. Trust me... you can do _a lot_ better.
> 
> 
> Consider wall-mounted bipole or dipole surrounds around half way down your seating area, and ideally another pair of bipole surrounds at the back for 7.1. That'll be a huge improvement.
> 
> 
> The layout with your back wall is tricky, so either ceiling-mount the rears, or wall-mount them to the sides behind the seating area, or stand-mount them.
> 
> 
> You can also have just one pair of dual-monopole surrounds (like the Infinity BETA ES250 or JBL's P52OWS ) and still go 7.1
> 
> 
> In any case, surrounds in your room should be at least a foot above seated ear-level.
> 
> 
> The are a couple of dipole-bipole threads here on AVS.
> 
> Some excellent speakers include Monitor Audio BFX , Paradigm's ADP surrounds and Axiom's QS8 .



HEHEE! Guys, I appreciate all the HT advise but I am *really* just looking for the acoustical parts right now.


Those are the 7.1 channel rears/ In that picture I have turned them towards the rear wall in "workout" mode. They are turned around in "movie" mode.


My 5.1 side speakers are Polk Fxi5's that are mounted up on the wall at a 90 degree angle to the center viewing spot.


As seen in this older picture













Please, is there any advise on the rear wall sound panel placing?


----------



## Weasel9992




> Quote:
> Originally Posted by *tleavit* /forum/post/16744868
> 
> 
> Please, is there any advise on the rear wall sound panel placing?



Yep. I'd get the rear corners floor to ceiling with 4" traps, then do maybe two or three 6" traps on the back wall.


Frank


----------



## Electric_Haggis




> Quote:
> Originally Posted by *tleavit* /forum/post/16744868
> 
> 
> HEHEE! Guys, I appreciate all the HT advise but I am *really* just looking for the acoustical parts right now.
> 
> 
> Those are the 7.1 channel rears/ In that picture I have turned them towards the rear wall in "workout" mode. They are turned around in "movie" mode.
> 
> 
> My 5.1 side speakers are Polk Fxi5's that are mounted up on the wall at a 90 degree angle to the center viewing spot.
> 
> 
> As seen in this older picture
> 
> 
> 
> 
> Please, is there any advise on the rear wall sound panel placing?




Ah, I see.


Well it's a little hard to say for sure without listening to the room, but off the batt, I'd say this...


* Your side-wall panels are perhaps a little high. You could try mounting them closer to the listening position, but it isn't too critical.

Ideally, get two rows of panels - one lower down than the current ones, and another higher row.


* As for the back wall, try moving the 3 front-centre traps from your front wall to the back wall and see if you can pick the difference. They'd likely be much better served there. You'll still have two traps at the front, and the projector screen will already be helping somewhat.


* The legendary Ethan Winer (a man who knows more about acoustics than most of us) isn't nearly as fussed about the front wall as the back. Look him up and read through some of his stuff. He's also on YouTube.


* If you're still getting a fair bit of bass-boom - as you'd expect in that room - then more corner traps will always help.


A few pages back, you'll see that I had some questions about bass traps in my room. I resolved to make Toblerone-shaped corner traps, made from stacks of triangular-cut panel (fibreglass, rockwool, polyester, whatever.)


Generally, these will be more effective than just having thinner panels laid against the corners.... and they'll be a damn sight cheaper.


----------



## tleavit




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16746876
> 
> 
> Yep. I'd get the rear corners floor to ceiling with 4" traps, then do maybe two or three 6" traps on the back wall.
> 
> 
> Frank



Thx guys


Where would be the best spots for the rear wall panels, up high, centered or down low?


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/16753090
> 
> 
> Thx guys
> 
> 
> Where would be the best spots for the rear wall panels, up high, centered or down low?



To use a billiards analogy, they would go on the cushion (rear wall) where the ball (sound) would strike going from the LCR speakers to the listeners.


----------



## Ethan Winer




> Quote:
> Originally Posted by *tleavit* /forum/post/16753090
> 
> 
> Where would be the best spots for the rear wall panels, up high, centered or down low?



Centered at seated ear height.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/16753484
> 
> 
> To use a billiards analogy, they would go on the cushion (rear wall) where the ball (sound) would strike going from the LCR speakers to the listeners.



Nice!










Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16754058
> 
> 
> Nice!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Frank



You can use it, Frank.


----------



## KERMIE

Is it necessary to Treat the entire front wall behind the screen if the Screen covers 2/3rds of the wall. If you trying to stop reflections from rear speakers it seems the mid/highs would hit the screen and not go through it.


Just a question...thanks


----------



## Dan Woodruff

Kermie,


I can tell you that my room sounds better with the entire screen wall treated. As a matter of fact, I put up a second layer of 1 inch Linacoustic RC and the sound improved exponentially.


Your mileage may vary.


----------



## tleavit




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16754008
> 
> 
> Centered at seated ear height.
> 
> 
> --Ethan



Even with a long extended rear like that? I was thinking that I need the entire rear treated (kind of like the front). The wall is bare right now but it is double walled (with double R19 in it) and double sheet 5/8ths sheet rock.


That rear wall is a good 25' from the listening position. I figured sound waves back there are all over the place and I don't want them bouncing back.


Is that logical at all?


----------



## nathan_h

Logical, yes, but not accurate. 25 feet is a long way. Some treatment is useful, like what Ethan suggests. But for anything other than that "first reflection point" your ears/brain will easily differentiate between direct and reflected sound.


Bass trapping, even in a room that large, will probably be (more) worthwhile. That's going to be very thick and spread over corners.


----------



## KERMIE




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/16755326
> 
> 
> Kermie,
> 
> 
> I can tell you that my room sounds better with the entire screen wall treated. As a matter of fact, I put up a second layer of 1 inch Linacoustic RC and the sound improved exponentially.
> 
> 
> Your mileage may vary.




Thank you Dan...I was planning on 2" on entire Front wall and Base traps in corners. I will continue to move forward as planned.


----------



## tleavit




> Quote:
> Originally Posted by *nathan_h* /forum/post/16757458
> 
> 
> Bass trapping, even in a room that large, will probably be (more) worthwhile. That's going to be very thick and spread over corners.



For the bass traps the plan was to get the same 4" thick panels without the wood backing.


----------



## firebrick

I finally got a monster subwoofer and have found the best place for it is along the middle of the back wall. I have superchuck bass traps in the front and cant do corner traps in the back. what i could do is a corner trap on the ceiling directly above the sub, and/or a 6 inch trap placed on the wall directly above the sub. The wall is only 1 drywall layer thick unfortunately and it really moves when the sub is hitting low notes. Any thoughts? And yes I do need to get an spl meter to get some readings.


----------



## Terry Montlick




> Quote:
> Originally Posted by *firebrick* /forum/post/16760421
> 
> 
> The wall is only 1 drywall layer thick unfortunately and it really moves when the sub is hitting low notes.



Does it rattle audibly?


----------



## firebrick




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16760579
> 
> 
> Does it rattle audibly?



fortunately no, hopefully wont start either. you can sure feel it though. and the light sconces do rattle so im not sure what to do with them except maybe change them for something rigid.


----------



## Terry Montlick




> Quote:
> Originally Posted by *firebrick* /forum/post/16761752
> 
> 
> fortunately no, hopefully wont start either. you can sure feel it though. and the light sconces do rattle so im not sure what to do with them except maybe change them for something rigid.



Yes. Change the sconces or fasten them so they don't rattle. Feeling the wall vibrate is fine.


Rattles typically happen at high decibel levels. They generate non-linear distortion.


- Terry


----------



## firebrick

how do i know whether or not i need more bass traps? what do you think about putting a gik 6" directly above my sub? good/bad? the sub is a monster, a seaton submersive, so im thinking the more traps the better but i havent done measurements as i am not very calibration educated.


----------



## erkq




> Quote:
> Originally Posted by *firebrick* /forum/post/16761752
> 
> 
> fortunately no, hopefully wont start either. you can sure feel it though. and the light sconces do rattle so im not sure what to do with them except maybe change them for something rigid.



Mine's an IB sub with 8 woofers. Even in a 1 year old well built house it makes the structure in the walls and roof creak. I guess there's nothing to do but turn down the volume?


----------



## Norman Varney

After speaker and listener locations are optimized, I would start out by absorbing each first order reflection for each front speaker on all six surfaces. I would then look at diffusing the first order reflection points for all surround speakers. With a room length well beyond 25' and an opening at the side wall to another room, you probably don't have terrible modal issues. Corner traps in all 8 corners should be a good idea to smooth out existing room modes as well as reverberation times. Have someone clap their hands in front of each speaker as you listen from your primary spot and place treatment (probably absorption in your case) where needed to control any slap echos. From there you'll need to determine if more absorption is needed to control lingering frequencies. The idea is to make the room disappear visually and sonically. Often people use too much mid and high frequency absorption making the room sound too dead above 500Hz. and sloppy below. Be sure to re-calibrate the electronics after physical changes are made.


----------



## tleavit




> Quote:
> Originally Posted by *pepar* /forum/post/16753484
> 
> 
> To use a billiards analogy, they would go on the cushion (rear wall) where the ball (sound) would strike going from the LCR speakers to the listeners.



When I use my laser pointer and mirror trick from my listening postion, I have the speaker well covered at that front refection point (especially the tweeter).


Im actually going to shoot for ceiling mounts now. Im going to use the laser trick to get 2 panels mounted on the ceiling at their reflection points from the center channel. I'll use my 2 2" panels for that (which are currently siting in the front corners as base taps until I get some real base traps.


----------



## jjmbxkb

Hi, I am going to build a home theater as part of finishing my basement. As the the picture shows, the room is 20' by 15', plus bump outs on two sides. The fourth side of the


room (the right side of the drawing) opens to the rest of the basement. I also tried to show locations of the stage (on the right side of the drawing), speakers, subwoofer(s),


and an ajacent finished bathroom.


As a newbie to HT, I've read many, many threads on AVS, but still not sure what I have to do regarding many aspects of acoustic treatment. I plan to spend up to $500.


To start off, my first questions are about the front wall (the wall on right side of the drawing).

1. There is a bump out (4' wide by 2' deep by 8' high) on the screen wall. It's right in the middle of the 15' long wall(red circle 1), and will be right where I plan to put


the center speaker (With grill cloth-covered panel). What kind of treatment should I do to this cavity?

2. Referring to the area labeled by the red circle 2, what kind of materials should I apply at the corner of the stage, where I will be hiding Left, Right speakers and may be


subs?


I am all ears and appreciate any help.


----------



## djakes

Hi all,

I'm continuing my planning for our new HT. You all have put a lot of knowledge out there for us newbies, so thanks. I hope you can take a look at what I'm thinking and provide any sound treatment advice that you may have.


Specs

Finished inside dimensions (including false screen wall) = 12'10 x 25'

Ceiling height = 7'10 for first 11' from screen (to enclose utilities), 9' for remaining depth

West wall and Southwest two small walls = Staggered studs, 5/8 DD + GG

North, East, and South walls = RSIC-DCO4 isolated 2x4 double walls spaced 2 from concrete wall. Apply 5/8 DD + GG

Ceiling = Use RSIC-EXTO4. Apply 5/8 DD+GG

Insulate walls with R13 (plus vapor barrier on concrete walls)

Screen = 2.35:1 SMX 120w X 51.1"h X 130.4"diag

Stage = Sand filled, but not yet sized. Separated from walls.

Riser = Insulation filled, not yet sized. Separated from walls.

Door = Safe N Sound exterior door with exterior trim











1) I plan to put tri corner bass traps in the false wall. But since there are no 90 degree angles in the back of the room is a rear bass trap required? If so, how do you suggest I build it?

2) I'm considering sound absorbing panels on the first reflection point (which is likely to be on the door. Are there any concerns with that?

3) What other suggestions do you have for sound isolation in this room?


Regards, DJ


----------



## pepar




> Quote:
> Originally Posted by *djakes* /forum/post/16774582
> 
> 
> 
> 1) I plan to put tri corner bass traps in the false wall. But since there are no 90 degree angles in the back of the room is a rear bass trap required? If so, how do you suggest I build it?



"Acoustically," why not make the rear square and use superchunk corner traps and acoustically transparent cloth to create the diagonal corners a la your drawing?


----------



## djakes

Thanks pepar,


That's certainly something to think about. I didn't go that route originally because my thinking is that the rear speakers would be too close to the last row. And other discussions I read said that having the rear wall too close to the seats adds a "boomy" sound. Compromise, compromise, compromise! But which would be the best alternative?


----------



## pepar




> Quote:
> Originally Posted by *djakes* /forum/post/16775053
> 
> 
> Thanks pepar,
> 
> 
> That's certainly something to think about. I didn't go that route originally because my thinking is that the rear speakers would be too close to the last row. And other discussions I read said that having the rear wall too close to the seats adds a "boomy" sound. Compromise, compromise, compromise! But which would be the best alternative?



Yes, all definitely true. My suggestion of triangular traps in the corner (as in the link in my sig) would yield the exact same floor plan and hide big hunky traps that a lot of people find difficult to hide.


----------



## KERMIE

If my room is too small to get quality corner traps will soffit traps all the way around work sufficient? I can have corner traps from floor to about 5 feet but above that will be tough with using sconces. In addition to my surrounds being too close to the corners.


Thank you


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *pepar* /forum/post/16774613
> 
> 
> "Acoustically," why not make the rear square and use superchunk corner traps and acoustically transparent cloth to create the diagonal corners a la your drawing?




Those are foundation walls.


----------



## djakes

Yeah Big, you're right that they're foundation walls (not so easily moved!).


Maybe KERMIE's question about using soffits for bass traps is another alternative for my HT?


Regards


----------



## pepar




> Quote:
> Originally Posted by *BIGmouthinDC* /forum/post/16776871
> 
> 
> Those are foundation walls.



The diagonals? Nevermind . .


----------



## KERMIE

If just the soffit is the case, do you leave the face and the bottom open, then fill with 4" ridged fiberglass?


Thank you


----------



## Hudda




> Quote:
> Originally Posted by *pepar* /forum/post/16774613
> 
> 
> "Acoustically," why not make the rear square and use superchunk corner traps and acoustically transparent cloth to create the diagonal corners a la your drawing?





Hey Pepar,


How do the superchunk corner traps compare to thick corner traps with some air behind them? The type with air behind them are much bigger but if you can accommodate them they provide more bass absorption don't they?


TIA


Chris


----------



## pepar




> Quote:
> Originally Posted by *Hudda* /forum/post/16780314
> 
> 
> Hey Pepar,
> 
> 
> How do the superchunk corner traps compare to thick corner traps with some air behind them? The type with air behind them are much bigger but if you can accommodate them they provide more bass absorption don't they?



The solid ones are better, but here is the data for you to look at yourself.


----------



## Weasel9992




> Quote:
> Originally Posted by *Hudda* /forum/post/16780314
> 
> 
> How do the superchunk corner traps compare to thick corner traps with some air behind them? The type with air behind them are much bigger but if you can accommodate them they provide more bass absorption don't they?



The testing we had Riverbanks Acoustic Lab certainly indicates that the corner-filling design does out perform the panel straddling the corner design.


Frank


----------



## Ictusbrucks

I am soon going to be installing some GIK tri-traps and 244 panels, but before I do I'd like to measure my room's frequency response to know where things are now.


I have a Pioneer SC-05 receiver which has the MCACC with EQ, but it doesn't give enough points of adjustment in the bass frequencies to give me enough information. But I can hear some serious "one note bass" and overall boominess. Room is 26'L x 13'W x 12'H




Only trouble is, I am a complete n00b when it comes to which type of product I should use for this. Can this be done relatively well using a laptop and microphone? If so, could I use the microphone that came with my SC-05 receiver, or is do I need to buy an actual SPL meter for these readings???


Is there any free software that can just take input from a mic and spit out nice detailed graphs? I know I saw a link earlier but forgot to bookmark and now can't find much.


Thanks!

Ryan


----------



## erkq




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16784839
> 
> 
> I am soon going to be installing some GIK tri-traps and 244 panels, but before I do I'd like to measure my room's frequency response to know where things are now.
> 
> 
> I have a Pioneer SC-05 receiver which has the MCACC with EQ, but it doesn't give enough points of adjustment in the bass frequencies to give me enough information. But I can hear some serious "one note bass" and overall boominess. Room is 26'L x 13'W x 12'H
> 
> 
> 
> 
> Only trouble is, I am a complete n00b when it comes to which type of product I should use for this. Can this be done relatively well using a laptop and microphone? If so, could I use the microphone that came with my SC-05 receiver, or is do I need to buy an actual SPL meter for these readings???
> 
> 
> Is there any free software that can just take input from a mic and spit out nice detailed graphs? I know I saw a link earlier but forgot to bookmark and now can't find much.
> 
> 
> Thanks!
> 
> Ryan



Prices are very approximate... from memory... just to give you an idea. This stuff is pretty cheap.


I use:


1. Room EQ Wizard is free and GREAT! I run it on Windoze.


2. LinearX M31 calibrated mic. Comes with it's calibration curve you can enter into Room EQ Wizard if you want. About $100


3. Behringer MiniMIC modeling mic pre-amp. I don't use any of the modeling settings, of course. It was just a nice cheap mic pre-amp with an analog VU meter. It's good to 6Hz! About $89


4. Then I got an M-Audio Transit to get the pre-amp output into the laptop's USB port and Room EQ Wizard's test tones into the audio system. About $50


5. Last, I use Behringer's Feedback Destroyer Pro to adjust out those bothersome "humps". It's a multi-band parametric eq that works extremely well for tuning sub-woofers. About $99


----------



## Ictusbrucks

Thanks alot for that info! I just got REW 4.11 and it looks like it does more than I'll need.


Just so I'm clear, what is the difference between using a Microphone and an SPL meter when using RoomEQ??? Does an SPL meter also need any kind of pre-amp?


Also, the M-Audio Transit, that is handling both the Mic into the laptop and also allows you to go from mini to RCA???


The Behringer feedback destroyer sounds neat.... but I think I might be able to adjust the EQ to a finer level if I use the RS232 port from my receiver and then install some software but I haven't gotten that far yet


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/16785193
> 
> 
> 
> 2. LinearX M31 calibrated mic. Comes with it's calibration curve you can enter into Room EQ Wizard if you want.



And you definitely should!


----------



## pepar




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16785237
> 
> 
> Thanks alot for that info! I just got REW 4.11 and it looks like it does more than I'll need.
> 
> 
> Just so I'm clear, what is the difference between using a Microphone and an SPL meter when using RoomEQ??? Does an SPL meter also need any kind of pre-amp?



Not exactly sure what you're asking, but REW has SPL measuring function. It does need a standalone SPL meter to calibrate it to reference once at the beginning of the session.



> Quote:
> Also, the M-Audio Transit, that is handling both the Mic into the laptop and also allows you to go from mini to RCA???



Technically, no _actually_, you are using the line in and line out of the "soundcard." The mic's preamp does not pug into a mic input; it goes into the line input. Line output goes to the device/channel being tested.



> Quote:
> The Behringer feedback destroyer sounds neat.... but I think I might be able to adjust the EQ to a finer level if I use the RS232 port from my receiver and then install some software but I haven't gotten that far yet



What would you be adjusting in your receiver via that RS232 port?


----------



## erkq




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16785237
> 
> 
> Thanks alot for that info! I just got REW 4.11 and it looks like it does more than I'll need.



More than I need too. Just use what you need and forget the rest. It's like Word or Excel.


> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16785237
> 
> 
> The Behringer feedback destroyer sounds neat.... but I think I might be able to adjust the EQ to a finer level if I use the RS232 port from my receiver and then install some software but I haven't gotten that far yet



I dunno... I think you'd be hard-pressed to find a finer level of control than 24 parametric eq bands for a subwoofer. But maybe. I have no idea what's in today's "room eq" receivers.


----------



## Hudda




> Quote:
> Originally Posted by *pepar* /forum/post/16780357
> 
> 
> The solid ones are better, but here is the data for you to look at yourself.




Thanks Pepar and Frank!


Chris


----------



## Ictusbrucks




> Quote:
> Originally Posted by *pepar* /forum/post/16785590
> 
> 
> Not exactly sure what you're asking, but REW has SPL measuring function. It does need a standalone SPL meter to calibrate it to reference once at the beginning of the session.




I am talking about how the HomeTheaterShack guide says you can use a Mic or an SPL meter:



> Quote:
> We recommend the Behringer ECM8000 microphone (with a proper preamp) or the Galaxy CM-140 SPL meter for full range measurements. Limit your measurements with the Radio Shack SPL meters to 3KHz.




So you are saying that you NEED an SPL meter for calibration? HTS seems to suggest you can use either/or. Could the entire setup be done just from a mic or SPL meter?


I'm not sure why you need a preamp with a mic, do you also need a preamp with an SPL meter?


----------



## pepar




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16789772
> 
> 
> I am talking about how the HomeTheaterShack guide says you can use a Mic or an SPL meter:
> 
> 
> "We recommend the Behringer ECM8000 microphone (with a proper preamp) or the Galaxy CM-140 SPL meter for full range measurements. Limit your measurements with the Radio Shack SPL meters to 3KHz. "
> 
> 
> So you are saying that you NEED an SPL meter for calibration? HTS seems to suggest you can use either/or. Could the entire setup be done just from a mic or SPL meter?



I believe that they are referring to using a Radio Shack SPL meter as a measurement mic. In any case, one needs an SPL meter to calibrate REW to a sound pressure level. Generate a test signal, either with REW or from an external source; held next to the test mic, measure it with an SPL meter and "tell" REW what the level is that it is "seeing" on the measurement mic. If one is actually using the RS meter as a measurement mic, then it will both indicate the SPL and send the signal to REW.



> Quote:
> I'm not sure why you need a preamp with a mic, do you also need a preamp with an SPL meter?



The RS meter has a line out that can connect directly to the soundcard's line input. (Mic inputs should NOT be used.) The measurement mics I am familiar with - the EMM8 and the Audyssey Pro mic - need pre-amps because they do not output a line level signal.


I really don't think that they are saying "either or" wrt the RS meter and a calibrated mic when they qualify it with "Limit your measurements with the Radio Shack SPL meters to 3KHz." I got myself into a brouhaha on the Audyssey thread trying to point out the limitations of the RS meter in this application and I don't care to do it here as well. Everybody can use whatever they want to.


----------



## erkq




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16789772
> 
> 
> So you are saying that you NEED an SPL meter for calibration?



As pepar said, "yes." But Personally, I'm not interested in SPL calibration so I don't bother. I have a tri-amp's system and the Behringer FBD for the subwoofer. I just use the emasurements to flatten and balance things out. Then I turn up the volume to where I want for a particular movie/audience/time of day.


----------



## rutlian

Just recently added absorption panels in my HT, enclosed is a few pictures can someone advise me if it is too high from the floor? Thank you very much.

first 2 photos are the new setup (2X4X1) it also shows the panels below but I took that out, should I put it back? last photo was the old setup. (1 2X4X2) is now on each side of the screen and also added 2 2x4x1 just below the screen hanged rectangular. Any advised would be appreciated.


----------



## docwhorocks

In the early planning stage of my dedicated HT. The room is 25'x14'. The current plan is a false wall. From the flase wall to the finished back wall is 22'. On the front left wall next to the false wall is a 4'x4' egress window. I'm trying to figure out the best way to cover this window, but not drywall over it completely.


My first thought was to make a removeable drywall block and then put a 4'x4' sound panel over it. Thus covering up the seems from the drywall block. But then I thought, why not just sink the sound panels into the wall. Is this a bad idea?


The picture below is rough mock up (close to scale, but not exact). It was when I had the thought of sound panels covering the wall, not imbeded in the wall. The red x is where the egress window is.


Currently there are not even stud walls up. The picture is just 1 idea done with sketchup.


Any and all thoughts on this would be apprecited. Everything in the room is up for change, except for the beam across the ceiling. The door placement can be moved to any either of the blue Xs. The columns are just an idea and can be ditched.











Thanks for any and all input


----------



## BrotherAaron

I'm towards the end of my theater build and plan on treating the the whole front wall with linacoustic, the lower side and back wall with linacoustic 44" with polyester batting on the upper wall. I have a front wall "room" that is 4' deep by 12' wide. It is mostly enclosed, much like a closet. Its enclosed on all sides except the right side wall(which will house my components) and the front wall which has a 6-8" wall along the outer edges (top and 2 sides). I am going to do a 120" AT screen and GOM along below the screen down to the stage. In my research about bass traps and room acoustics, I am now wondering that due to the "enclosed" space on the screen wall will bass traps be as big of an issue or have I messed up in my design and do I need to change something now?


----------



## Ethan Winer

I don't totally understand the question, but I can tell you that lack of left-right symmetry is going to be a problem. More here:

How to set up a room 


--Ethan


----------



## BrotherAaron

Hi Ethan, I assume you are referring to my post. As far as the room design, I am stuck with it







My concern is basically having the front wall that is not fully open acoustically. it has been "boxed in by the 8" walls on the side and top. Will this affect bass response acoustically? I have noticed a huge loss in loudness, but seems to reduce the boominess of the room. Is it the loss of the 3 boundry db increase or do i have more serious acoustic issues here?


P.S. Please don't laugh, I stink at those CAD programs


----------



## nathan_h

You could build a dividing wall along the right hand side that makes the main space symmetrical. Leave openings to walk into each row of seats.


It won't be perfect symmetry, because the left hand wall will be contiguous and the right hand "wall" won't be. But it will be better than not having the dividing wall. And you have the added benefit of mids+highs seeing the room as symmetrical (good for non-bass frequencies) and the bass finding the gaps and seeing the larger room as not-symmetrical (good for bass frequencies).


----------



## maxl

I am making a dedicated home theatre in a 12' by 13' (by 8') room. I am planning only one raw of seats and rather simple set-up (no stage or ramp), but want to make sure I am getting best possible picture and sound.


First, few words about personal preferences - I tend to like "dead" rooms with close to no reverb. Also, given that this is a rather small room, and I'll have to put seats close to the rear wall, there is little chance of quality reverb, so I'd rather err on the side of no reverb (not sure how correct my logic is).


So here is my plan:


1. Front wall - completely covered by 2" of Roxul or other mineral wool/board covered by acoustically transparent fabric. Due to space limits, I am not making the stage - the screen will just be attached to the wall over the sound treatment.

2. Rear wall - same as the front + 2 triangular bass traps (superchunks) in the corners

3. Sides - a strip of 2" sound treatment (absorption) along the entire wall, starting about 2 feet from the floor and ending a foot above ear level. non-covered-2 layer drywall everywhere else.

4. Floor - plush carpet on concrete

5. Ceiling - a small spot (something like 2'x3') of the same absorption treatment in the first reflection point and non-covered drywall everywhere else. The ceiling is flat with soffit above the seating area.


Does this make sense? Do I need any diffusion panels? I got an impression diffusion treatment is not useful for such small spaces...


Thanks!


----------



## nathan_h

I'd recommend that you double the thickness, and cover only half the wall area you describe.


Focus on the first reflection points.


And if you can quadruple the thickness and cover just a 1/4 of the wall area (while still getting all the first reflection points), that is even better.


You'll avoid killing off the high end, get much more even, broad band, mid-band, and bass absorption.


----------



## maxl




> Quote:
> Originally Posted by *nathan_h* /forum/post/16817195
> 
> 
> I'd recommend that you double the thickness, and cover only half the wall area you describe.
> 
> 
> Focus on the first reflection points.
> 
> 
> And if you can quadruple the thickness and cover just a 1/4 of the wall area (while still getting all the first reflection points), that is even better.
> 
> 
> You'll avoid killing off the high end, get much more even, broad band, mid-band, and bass absorption.



So just to make sure I understand it right - you are suggesting 4" of sound treatment on the primary reflection points? I cannot get 8 inches, but I could get, for example, two more superchunk bass traps (for 4 total).


Also, what do you suggest I do with the front and back walls? I'm going for a 7.1 setup.


----------



## Ethan Winer




> Quote:
> Originally Posted by *BrotherAaron* /forum/post/16811713
> 
> 
> My concern is basically having the front wall that is not fully open acoustically. it has been "boxed in by the 8" walls on the side and top. Will this affect bass response acoustically?



In all honesty I can't tell, but at least now with your new drawings the situation is perfectly clear. Generally, large open areas are a Good Thing. But lots of insulation as you propose will certainly help further.


--Ethan


----------



## nathan_h




> Quote:
> Originally Posted by *maxl* /forum/post/16817871
> 
> 
> So just to make sure I understand it right - you are suggesting 4" of sound treatment on the primary reflection points? I cannot get 8 inches, but I could get, for example, two more superchunk bass traps(for 4 total).



4 inches is great. Much better than 2 inches.


And more of the superchunk style corner bass traps will be useful. It's almost impossible to have too many of those.



> Quote:
> Also, what do you suggest I do with the front and back walls? I'm going for a 7.1 setup.



Front and back walls have first reflection points, too. Hit those, but don't just generically cover the whole wall or large swaths of wall.


----------



## tleavit




> Quote:
> Originally Posted by *nathan_h* /forum/post/16818562
> 
> 
> 4
> 
> Front and back walls have first reflection points, too. Hit those, but don't just generically cover the whole wall or large swaths of wall.



From what I have gathered from "acoustics 101" from this thread, you should cover the entire front wall (and the side/rear walls completely under ear height). Not true?


----------



## Elill

Every few pages of this thread someone is asking the same question and we never seem to get anywhere with an agreed conclusion. That's fair enough in some respects as people are entitled to a different view of the world.


BUT, because this has been a constant point of frustration I've followed Dennis' advice and got a copy of Sound Reproduction by Floyd Toole and the somewhat older, Master Handbook fo Acoustics by Everest. They contain more information then you could imagine and back up my old view that text books are better than the internet - just to be clear this isn't a shot at this forum.


So, do yourselves a favour and get a copy of Sound Reproduction and start reading (its very long, I've only read a few chapters of interest so far).


One of the main things I've discovered to date is that many of the treatment options many people use here aren't really that necessary or can lead to poor 2 channel quality (for example) - so you need to be very careful in what you spend your cash on and get something suitable for your specific needs, not that of someone else.


Highly Recommended.


P.S. these books aren't that cheap, but in the overall scheme of things they are nothing and will probably save you some coin in the long run.


----------



## tleavit




> Quote:
> Originally Posted by *Elill* /forum/post/16818845
> 
> 
> Every few pages of this thread someone is asking the same question and we never seem to get anywhere with an agreed conclusion. That's fair enough in some respects as people are entitled to a different view of the world.



That's very true. I think a lot of it has to do with the fact that you have to seriously filter what you read here to. you have to filter the advise since there is a lot of people here that have an economic interest in whats said.


----------



## unclepauly




> Quote:
> Originally Posted by *Elill* /forum/post/16818845
> 
> 
> One of the main things I've discovered to date is that many of the treatment options many people use here aren't really that necessary or can lead to poor 2 channel quality (for example)



Well I hope my first reflection absorption panels aren't one of those unnecessary treatment options.


----------



## nathan_h




> Quote:
> Originally Posted by *tleavit* /forum/post/16818586
> 
> 
> From what I have gathered from "acoustics 101" from this thread, you should cover the entire front wall (and the side/rear walls completely under ear height). Not true?



Neither true nor false. But definitely NOT a cookie cutter approach that works well in all (or even most?) situations.


There are advocates on both sides of the issue. But the scientific literature (nicely summarized in the Toole book mentioned above) would answer your question with the statement "Not true".


----------



## unclepauly

Yeah it's definitely true that you can make a room sound too dead. While there's a purity to the sound something just doesn't feel right like that.


----------



## Elill




> Quote:
> Originally Posted by *unclepauly* /forum/post/16819193
> 
> 
> Well I hope my first reflection absorption panels aren't one of those unnecessary treatment options.



I dont want to sit here and re-hash Toole's book, nor do I think I have the necessary knowledge to present sections of it that wont provide a biased view when read in isolation to the rest of his work.


Get the book.


Saying that'd I'd think twice about treating a room if you are into Stereo in a big way - I kind of am. But my problem is that I want to design a room with the treatments it needs, but that is hard to determine that until its built!


For example, I think chair rails look very classy with wall paper above. But I cant have a rail if I need to have some sort of treatment haning over it, because that'll look totally stupid. I dont want to put bass traps in later, because I want to wrap mouldings etc around it all to make it just look like an angled wall....so do I need traps or not? should I build soffits as normal or with 600mm 45degree bass traps in the wall/ceiling joint? These are all things I am trying to come to terms with before the room is built. But its becoming abuldantly obvious I'll have to build it - set up the gear, listen and then take it all out and finish decorating it and then put it all back....this I am trying to avoid.


----------



## pepar

Newer "thinking" encompasses multichannel systems. Some of the older works are from the stereo audio era, and studio acoustics.


----------



## Weasel9992




> Quote:
> Originally Posted by *nathan_h* /forum/post/16818562
> 
> 
> 4 inches is great. Much better than 2 inches.
> 
> 
> And more of the superchunk style corner bass traps will be useful. It's almost impossible to have too many of those...
> 
> 
> Front and back walls have first reflection points, too. Hit those, but don't just generically cover the whole wall or large swaths of wall.



Great advice. Rule-of-thumb type information is common and it's good as far as it goes, but it's kinda like axioms and proverbs. They're meant to cover a lot of ground, but context is important. Sometimes it's definitely the right thing to cover all of the front wall; other times it definitely isn't. Each room is it's own context and should be viewed that way. Personally I like to place lots of 4" broad band panels in smaller rooms because they're more efficient...they cover more sonic ground in a more balanced way using fewer panels.


Frank


----------



## maxl




> Quote:
> Originally Posted by *nathan_h* /forum/post/16818562
> 
> 
> 4 inches is great. Much better than 2 inches.
> 
> 
> And more of the superchunk style corner bass traps will be useful. It's almost impossible to have too many of those.
> 
> 
> 
> 
> Front and back walls have first reflection points, too. Hit those, but don't just generically cover the whole wall or large swaths of wall.



Should I worry about dispersion panels at all? The room is almost a perfect square (12' x 13') with one row about 3 feet away from the back wall and 7.1 setup.


Thanks


----------



## Terry Montlick




> Quote:
> Originally Posted by *nathan_h* /forum/post/16818562
> 
> 
> 4 inches is great. Much better than 2 inches.
> 
> ...
> 
> Front and back walls have first reflection points, too. Hit those, but don't just generically cover the whole wall or large swaths of wall.



I'm afraid such a strategy for the front wall makes no sense. Main speakers face away from this wall, into the room. Very little middle to high frequency energy is directed at the front wall first reflection points. As for low frequencies (which could potentally cause 1/4 wave cancelation via reflection from these points), a mere 4 inches of porous absorption is not going to help.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16823324
> 
> 
> I'm afraid such a strategy for the front wall makes no sense. Main speakers face away from this wall, into the room. Very little middle to high frequency energy is directed at the front wall first reflection points. As for low frequencies (which could potentally cause 1/4 wave cancelation via reflection from these points), a mere 4 inches of porous absorption is not going to help.



"Dead End" is dead for multichannel reproduction?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16823340
> 
> 
> "Dead End" is dead for multichannel reproduction?



Not what I said.







It's just that the front wall early reflection points have no particular importance for treatment.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16823393
> 
> 
> Not what I said.
> 
> 
> 
> 
> 
> 
> 
> It's just that the front wall early reflection points have no particular importance for treatment.



Thanks. On a completely different subject then, is LEDE still recommended for multichannel reproduction?


----------



## Ethan Winer




> Quote:
> Originally Posted by *tleavit* /forum/post/16818586
> 
> 
> From what I have gathered from "acoustics 101" from this thread, you should cover the entire front wall (and the side/rear walls completely under ear height). Not true?



Not true, and Terry gave some reasons why. However, bass traps on the front wall always help. More here:

Front Wall Absorption 


As for the side walls, having absorption down by the floor is a waste, and not going to at least a foot above ear height leaves too much of the wall bare and reflecting. More here:

Early Reflections 
How to set up a room 


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16823412
> 
> 
> Thanks. On a completely different subject then, is LEDE still recommended for multichannel reproduction?












I didn't know that it ever was. LEDE was a fad for control rooms around a quarter century ago. No acoustic design idea ever fully dies.


----------



## maxl




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16823324
> 
> 
> I'm afraid such a strategy for the front wall makes no sense. Main speakers face away from this wall, into the room.



What about reflection of the sound from rears?


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16823560
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I didn't know that it ever was. LEDE was a fad for control rooms around a quarter century ago. No acoustic design idea ever fully dies.



Unfortunately, I built my house about 20 years ago and was still heavily influenced by that scheme when I upgraded my theater 4 years ago. Now I wonder if I should not remove the 2" Linacoustic behind the false wall.


----------



## nathan_h




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16823324
> 
> 
> I'm afraid such a strategy for the front wall makes no sense. Main speakers face away from this wall, into the room. Very little middle to high frequency energy is directed at the front wall first reflection points. As for low frequencies (which could potentally cause 1/4 wave cancelation via reflection from these points), a mere 4 inches of porous absorption is not going to help.



Yep, I was conflating two different goals. Earlier I wrote:


"And if you can quadruple the thickness and cover just a 1/4 of the wall area ... that is even better." That'd be an 8 inch panel.


Or a 4 inch panel bridged across a corner at 45degrees would be better than a 4 inch panel flat against the wall.


----------



## Ictusbrucks

Hello, looking for some feedback and ideas for treating my room. Currently my bass is AWFUL (polk DSW Pro600), many songs hear like one-note-bass and it just sounds muddy.



Dimensions are about 13'w x 26' L x 12' H. Unfortunately it is a kind of ackward space with all sorts of openings.


So with each picture I'll briefly outline my current treatment thoughts, please let me know if I'm in the right direction. For now I'm using all GIK products in my planning....


Sorry this first pic came out so dark:









Was thinking of using 6 Monster-Bass-traps, 3 in each front corner, stacked floor to ceiling. They would be a few inches from the front L/R speakers.


In addition, (3) 242 panels on the 1st reflection point by the recliner (where the picture is hanging), and I'll need some kind of acoustic curtains on the left. Not much I can do for the fireplace I guess?


Another 242 on the left wall between the two top windows, and (2) 242's on the 1st reflection on the ceiling.



Surround Left:









Would it be beneficial to use a Tri-Trap up in these top-rear corners??? Or would I be better off with a Monster-Bass-Trap here also???



Surround Right:









Again, Tri-Trap or Monster-bass in the upper back corner?


Was thinking of putting a single 242 panel on the back wall to soak up the sound, since one whole side is open I dont want uneven echos. Should I use multiple 242s there for that purpose?


Also, was thinking of putting some Tri-Traps in the stair-way ceiling, and possibly a 242 panel by where the banister meets the wall in that photo.


Sorry for what might be poorly constructed post.... I could post back with images depicting where I am thinking of the treatments if its not clear.


----------



## Roger Dressler




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16824403
> 
> 
> Hello, looking for some feedback and ideas for treating my room. Currently my bass is AWFUL (polk DSW Pro600), many songs hear like one-note-bass and it just sounds muddy.



Aside from acoustic treatments, if you can figure out a way to get at least 1 band of PEQ in there to tune out the room's primary resonance, you'd notice a huge benefit in solving the one note bass problem. Several subs have this facility. Not sure if there's a simple outboard box available, though. Which AVR are you using? Does it have any sort of EQ for the sub output?


If your system has no EQ for the sub, an option does exist. This thread describes the Anti-mode 8033. Worth a look.


----------



## tleavit

I read the first 20+ pages again (last time was about 1.5 years ago) and it gave me better direction. Looking for a few more suggestions.


Front bass traps: I'm looking at buying 4 more 2' x 4' ATS acoustics panels in bass trap config. They would be a triangle in the corner with their mount kit. They would be 4 inchs thick with no wood backs. I can stack 2 in the corner and they would fit perfectly and look pretty darn clean.


Here is an example where I threw in some of my normal panels for testing. I also put my sub location and bass trap location in the drawing below.













Here's something different!


I have found that a lot of sound is escaping into my house through my stairs going up (the rest of the room is sealed pretty good since I have double 5/8th sheet rock, double walls and double insulation). I drew this up real fast as an example.











At the end of the stairs is a solid wood door but it also is not "sealed". For example there is a half inch gap open on the bottom between it and the carpet.


What I was thinking of doing is putting some of the 4" 2' x 4' panels in locations that I marked with the red spray paint to help stop the sound bouncing upstairs. I would consider also lining the entire middle stair wall with linacoustic. I also want to figure out how to seal that door better.


Any advise would be apreciated.


----------



## rec head




> Quote:
> Originally Posted by *tleavit* /forum/post/16828863
> 
> 
> I read the first 20+ pages again (last time was about 1.5 years ago) and it gave me better direction. Looking for a few more suggestions.
> 
> 
> Front bass traps: I'm looking at buying 4 more 2' x 4' ATS acoustics panels in bass trap config. They would be a triangle in the corner with their mount kit. They would be 4 inchs thick with no wood backs. I can stack 2 in the corner and they would fit perfectly and look pretty darn clean.
> 
> 
> Here is an example where I threw in some of my normal panels for testing. I also put my sub location and bass trap location in the drawing below.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here's something different!
> 
> 
> I have found that a lot of sound is escaping into my house through my stairs going up (the rest of the room is sealed pretty good since I have double 5/8th sheet rock, double walls and double insulation). I drew this up real fast as an example.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> At the end of the stairs is a solid wood door but it also is not "sealed". For example there is a half inch gap open on the bottom between it and the carpet.
> 
> 
> What I was thinking of doing is putting some of the 4" 2' x 4' panels in locations that I marked with the red spray paint to help stop the sound bouncing upstairs. I would consider also lining the entire middle stair wall with linacoustic. I also want to figure out how to seal that door better.
> 
> 
> Any advise would be apreciated.



weather stripping and a threshold would be a good place to start.


----------



## Artzilla

I initially posted this in the Audyssey thread. It may not be appropriate for this thread because treatments are a final option, if an option at all but at the suggestion of people there, I'm listing it here to see if there are any who have any experience or feedback on this.


Help Please - Sound pressure & Audyssey Trouble-Got an RTA-what to do?


--------------------------------------------------------------------------------


I recently got the Integra DHC 9.9 conviced it was the answer to all my issues with my video and connectivity challenged older Yamaha RXV-1400. Pretty much - it was. But it created a new one.


Now that I've installed the Integra - something painful is happening in the room. It's more prevalent with Multi EQ on, but is present with no EQ whatsoever. After multiple calibrations with two subs from my previously identical set-up except the avr, and reducing the system to a single sub, the room is being pressurized to a painful degree even at very low volumes, with no EQ engaged at all. Audyssey exacerbates the issue. My sub is actually calibrated 3db lower than the other speakers and it still hurts. My wife and I both experience ear pain almost immediately and after a minute or 2, I swallow and my ears pop as if on an airplane. I want to emphasize this isnt' so much a volume issue - it's sound pressure. It doesn't occur on music but I can't even think about watching tv much less a blu ray unless I do the following.


It's not just the sub. To eliminate the issue, I've had to turn the sub off and set my mains at 80hz so nothing below that comes out of my system. Even at that setting, If I engage the eq (not dynamic eq-can't even think about using that) the problem is back even with everything cut off at 80hz.


I have a great contact who was kind enough to let me use their spectrum analyzer. It's an Audio Control SA 3050. I have figured out how to measure each speaker individually and will use the full mono setting to check the summed effect of all speakers.


My question, unless someone has a eureka solution to my issue is: Can I somehow use REW with the RTA to actually get the readings into the computer as opposed to manually logging all of the results. I have a lot of testing to do and it's going to be a ton of data when I look at measuring speakers 7.1, 7.2, 7.3 individually and summed, as well as the inevitable various placements I'll have to experiment with for the sub or subs - whatever works. (Obviously my issue with the Yamaha was not enough bass-thus the 3 subs - I'd like to get down to 2 just to keep headroom but will drop to one if it fixes it)



FYI: I've used the input volume attenuation and other suggestions posted by batpig. No tangible results


Room dimensions: 29' 6" x 22'8" x 7'11" with open doorways on opposite corners of the lenght of the room. Large window and Slider on left & right framing the seating positions.


Equip:


Integra DHC 9.9

Rotel 1095

B&W 803s

B&W 602 S2 (pair for center)

B&W CDM SNT surrounds

SVS 25-31 & 20-39 both tuned to 20hz - this was recommended and approved by Ed at SVS and never caused the problem on the older unit.

Using Old Yamaha to power surrounds til I see if I can fix this before buying an surround amp. This used to be the heart of the system and neither this, nor the previous Yamaha 2090 exhibited this problem with the same room, mains & dual subs. The center & surrounds have changed over the years.


----------



## pepar




> Quote:
> Originally Posted by *Artzilla* /forum/post/16829216
> 
> 
> I guess trial and error is the way to go for the RTA & REW.
> 
> 
> The RTA only emits *wide band pink noise* - no sweeps. But I'll start there.



That might be all you need.



> Quote:
> I could have something wrong in the setup but I've experimented exhaustively and think I've tried every possible combination of settings to avoid this more demanding path and the possibility of room treatment.



Room treatments are always a good idea and necessary to get one's sound to the next level. But your issue is *so* weird that there must be something wrong other than a room node or two. PAIN?!?!



> Quote:
> Check on all the sub notes. Tried with and without processing and am back at no processing, have been for a while.



That is happens without the sub when mains are on large suggests that it is not the sub.


I feel like I'm reading a cliffhanger here, Artzilla!


----------



## Ictusbrucks




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/16825982
> 
> 
> Aside from acoustic treatments, if you can figure out a way to get at least 1 band of PEQ in there to tune out the room's primary resonance, you'd notice a huge benefit in solving the one note bass problem. Several subs have this facility. Not sure if there's a simple outboard box available, though. Which AVR are you using? Does it have any sort of EQ for the sub output?
> 
> 
> If your system has no EQ for the sub, an option does exist. This thread describes the Anti-mode 8033. Worth a look.



Thanks. I have a Pioneer Elite SC-05 which does have MCACC.... but as you said it doesnt really seem set up for the sub since there's really only one band for EQ in the bass range, then the next one is over 100hz (cant recall exactly right now).


I got myself a galaxy SPL meter and I am going to try and do some testing with RoomEQ Wizard to see how bad things are.



I see above people talking about sealing doors at the end of hallways... can I ask why? I thought you just didn't want sound to echo off the walls, what harm is it if sound gets past a door??? I have halls, rooms and stairs all leading out of my HT room, none of which I can 'seal up'


----------



## Artzilla




> Quote:
> Originally Posted by *pepar* /forum/post/16829324
> 
> 
> That might be all you need.
> 
> 
> 
> Room treatments are always a good idea and necessary to get one's sound to the next level. But your issue is *so* weird that there must be something wrong other than a room node or two. PAIN?!?!
> 
> 
> 
> That is happens without the sub when mains are on large suggests that it is not the sub.
> 
> 
> I feel like I'm reading a cliffhanger here, Artzilla!



You are, it's called, Is his wife going to kill him & when? How long does he have? I got lucky with a wife that likes football, Sci-Fi and action movies, and HT, but not being able to watch a movie or tv without this headache has turned her into......well, something else. Truth be told I'm far more bent about it than she is. Talk about expectations being dashed. I just read the praise the unit gets and how thrilled people are with it when they find that secret ingredient after their own brand of troubles for a whilethen "Eureka". I cross my fingers that I'll have my moment.


You're right about it not being the sub, or at least the sub alone. My mains are pretty capable, but they're not subs. Part of the reason for the Integra over the Marantz 8003 was the ability to adjust the spekaer x-overs by pair (And Audyssey XT & Dynamic EQ which make it worse rather than better) so I could run my mains lower than 80hz for the more articulate bass they provide within their comfort zone on music which is easily down to 60 if not 40 depending on individual taste. Make no mistake, I love bass, and prefer to run it a little hot when things are "normal". I was hoping the Integra & Audyssey would fill in the areas where I felt the Yamaha was bright and weak in mid-bass.


In the next hour or three I'm going to check the wiring again and do a quick run through of the speakers all on, full mono, with and without the sub, and post my results to see if they reveal anything.


----------



## glaufman

So let's get this right... when you've made no changes except for replacing the yamaha witht the new AVR, it all goes haywire... and when you go back the problem goes away..


that says it has to be either;

1) the new AVR is so much more capable than the old it's dispalying room/setup problems yuo never knew you had, or

2) a faulty AVR, or

3) a faulty job setting it up...


Not sure what ins/outs you have on the RTA, but I would start by using either the RTA, or preferably (at least in my world) REW, to inject a signal into the Integra's input and read it's preamp output ... make sure that's clean... if not, start looking at what settings affect it in a manner that's advantageous... if you can't find one, it's faulty...


----------



## CJO




> Quote:
> Originally Posted by *tleavit* /forum/post/16828863
> 
> 
> I At the end of the stairs is a solid wood door but it also is not "sealed". For example there is a half inch gap open on the bottom between it and the carpet.
> 
> 
> What I was thinking of doing is putting some of the 4" 2' x 4' panels in locations that I marked with the red spray paint to help stop the sound bouncing upstairs. I would consider also lining the entire middle stair wall with linacoustic. I also want to figure out how to seal that door better.
> 
> 
> Any advise would be apreciated.



This would help with the door issue:
http://www.soundproofingcompany.com/...c_door_bottom/ 


CJ


----------



## maxl




> Quote:
> Originally Posted by *Artzilla* /forum/post/16829276
> 
> 
> I want to emphasize this isnt' so much a volume issue - it's sound pressure. It doesn't occur on music but I can't even think about watching tv much less a blu ray unless I do the following.



This sounds VERY MUCH like a infra-sonic vibration (2-20Hz) - you cannot hear it, but certain frequencies can play pretty bad tricks with your brain. I did it in a lab, and could get similar symptoms of air pressure or even induce nausea and vertigo.


It is pretty much guaranteed that sounds of this frequency are not mixed into any commercial disks, so the frequency can be created either by the sound system or by the room. My bet would be on the room, taking into account how you could get the same result without a sub and with mains cut off at 80Hz. It is possible that something in the room has a sub-sonic resonance frequency that is excited by the sound system. Try moving things around etc.


----------



## erkq




> Quote:
> Originally Posted by *maxl* /forum/post/16830571
> 
> 
> This sounds VERY MUCH like a infra-sonic vibration (2-20Hz) - you cannot hear it, but certain frequencies can play pretty bad tricks with your brain. I did it in a lab, and could get similar symptoms of air pressure or even induce nausea and vertigo.
> 
> 
> It is pretty much guaranteed that sounds of this frequency are not mixed into any commercial disks, so the frequency can be created either by the sound system or by the room. My bet would be on the room, taking into account how you could get the same result without a sub and with mains cut off at 80Hz. It is possible that something in the room has a sub-sonic resonance frequency that is excited by the sound system. Try moving things around etc.



I would agree with only part of that 2-20Hz not occurring on commercial disks. But there is a distribution of likelyhood ranging from 2-5Hz being completely unlikely to 15-20Hz being fairly likely. Parts of Inside Man rattle my teeth and blur my vision. I'm sure it's lower than 20Hz.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/16830762
> 
> 
> I would agree with only part of that 2-20Hz not occurring on commercial disks. But there is a distribution of likelyhood ranging from 2-5Hz being completely unlikely to 15-20Hz being fairly likely. Parts of Inside Man rattle my teeth and blur my vision. I'm sure it's lower than 20Hz.



From his mains? He said "it" is there with the sub OFF and the mains at LARGE.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/16830774
> 
> 
> From his mains? He said "it" is there with the sub OFF and the mains at LARGE.



The quote I was responding to was this: "It is pretty much guaranteed that sounds of this frequency are not mixed into any commercial disks".


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/16830774
> 
> 
> From his mains? He said "it" is there with the sub OFF and the mains at LARGE.



If his mains (or even his sub) are putting out significant sound at 2-5 Hz, I'd like to buy them!


----------



## erkq




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16830838
> 
> 
> If his mains (or even his sub) are putting out significant sound at 2-5 Hz, I'd like to buy them!



Again... I was simply responding to the claim about frequency content of commercial disks; that one sentence I quoted above. That's it. That's all. That's where my comment stops. The disk. Frequency content of disks comes well before subs on or off in the signal chain.


----------



## Artzilla




> Quote:
> Originally Posted by *glaufman* /forum/post/16829710
> 
> 
> So let's get this right... when you've made no changes except for replacing the yamaha witht the new AVR, it all goes haywire... and when you go back the problem goes away..
> 
> 
> that says it has to be either;
> 
> 1) the new AVR is so much more capable than the old it's dispalying room/setup problems yuo never knew you had, or
> 
> 2) a faulty AVR, or
> 
> 3) a faulty job setting it up...
> 
> 
> Not sure what ins/outs you have on the RTA, but I would start by using either the RTA, or preferably (at least in my world) REW, to inject a signal into the Integra's input and read it's preamp output ... make sure that's clean... if not, start looking at what settings affect it in a manner that's advantageous... if you can't find one, it's faulty...



#1 was my first assumption followed by #3. The jury is still out. I have more work to do. I have not tried reinserting the Yamah. That will happen in the next day or two but I will run thoroughly through the RTA tomorrow.


----------



## Tong Chia




> Quote:
> Originally Posted by *Artzilla* /forum/post/16832354
> 
> 
> #1 was my first assumption followed by #3. The jury is still out. I have more work to do. I have not tried reinserting the Yamah. That will happen in the next day or two but I will run thoroughly through the RTA tomorrow.



Have you tried using only 1 of the mains ? If the problems go away it points a

speaker setup issue with the Integra.


A complete factory reset of the Integra may also help. It may have

configuration data that is messed up in NVRAM. You dealer can probably

help you.


If your RTA is capable, I suggest doing spot checks in the 5-15Hz region

to see if there is anything there.


----------



## Artzilla




> Quote:
> Originally Posted by *Tong Chia* /forum/post/16833125
> 
> 
> Have you tried using only 1 of the mains ? If the problems go away it points a
> 
> speaker setup issue with the Integra.
> 
> 
> A complete factory reset of the Integra may also help. It may have
> 
> configuration data that is messed up in NVRAM. You dealer can probably
> 
> help you.
> 
> 
> If your RTA is capable, I suggest doing spot checks in the 5-15Hz region
> 
> to see if there is anything there.



The rta cuts off at 25 hz but I've run test tones with no eq and


from 11.22-17.2 It's varies by only 1db with a 3 db jump at 20hz


10 db spike at 22.45hz. where it stays relatively flat until a 13 db hole at 44.9


I get a 5 db spike at 113.1


5-10 db suckouts from 142.5 - 179.6


a 6 db drop at 254hz, and a 14 db drop at 403 hz


6-7 db drop at 570.2.


Does this indicate any sort of inteligible pattern?


FYI: This was run w/dual subs and mains crossed at 60hz or 80hz. Can't remember which but it was pretty flat through the crossover area regardless.


----------



## KERMIE

Ethan,


Using your file here is what i found:












I read most of what you have on your site but what is this telling me about room treatments?


thank you for your help when you get a chance


----------



## pepar




> Quote:
> Originally Posted by *Artzilla* /forum/post/16834080
> 
> 
> The rta cuts off at 25 hz but I've run test tones with no eq and
> 
> 
> from 11.22-17.2 It's varies by only 1db with a 3 db jump at 20hz
> 
> 
> 10 db spike at 22.45hz. where it stays relatively flat until a 13 db hole at 44.9
> 
> 
> I get a 5 db spike at 113.1
> 
> 
> 5-10 db suckouts from 142.5 - 179.6
> 
> 
> a 6 db drop at 254hz, and a 14 db drop at 403 hz
> 
> 
> 6-7 db drop at 570.2.
> 
> 
> Does this indicate any sort of inteligible pattern?
> 
> 
> FYI: This was run w/dual subs and mains crossed at 60hz or 80hz. Can't remember which but it was pretty flat through the crossover area regardless.



What it doesn't seem like is anything that would cause you pain. Could you elaborate a bit on what you _think_ is causing your distress?


----------



## Weasel9992




> Quote:
> Originally Posted by *Artzilla* /forum/post/16834080
> 
> 
> The rta cuts off at 25 hz but I've run test tones with no eq and
> 
> 
> from 11.22-17.2 It's varies by only 1db with a 3 db jump at 20hz
> 
> 
> 10 db spike at 22.45hz. where it stays relatively flat until a 13 db hole at 44.9
> 
> 
> I get a 5 db spike at 113.1
> 
> 
> 5-10 db suckouts from 142.5 - 179.6
> 
> 
> a 6 db drop at 254hz, and a 14 db drop at 403 hz
> 
> 
> 6-7 db drop at 570.2.
> 
> 
> Does this indicate any sort of inteligible pattern?
> 
> 
> FYI: This was run w/dual subs and mains crossed at 60hz or 80hz. Can't remember which but it was pretty flat through the crossover area regardless.



I have to agree. That's really not bad at all. What are you hearing that's bothering you?


Frank


----------



## Artzilla




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16835724
> 
> 
> I have to agree. That's really not bad at all. What are you hearing that's bothering you?
> 
> 
> Frank



I can only describe it as "pressure". It's progressive. My wife notices it immediately and if you sit there a few minutes I end up with a naggin little pain and a ringing in my ear that lasts a while. With me, it's mostly the right ear and my wofe, the left. She sits on the left side of the couch and I'm on the right so it seems they are reflective sounds not direct, that's as close as I've come to isolating anything.


I can't isolate a particular frequency. Since my last post, I've manageg to use the rta and the single band eq on one of my subs to get the bass pretty darn flat all the way up to 160. Sure I've got some 4 db swings in there but for a little placement experimentation and a single band parametric eq - not too bad.


Problem now is, I got a replacement mic from my dealer to see if maybe that could be faulty, plugged it in and I get speaker detect errors. It's not emitting the test tones now. I'm beginning to think this is a buggy unit.


----------



## pepar




> Quote:
> Originally Posted by *Artzilla* /forum/post/16837934
> 
> 
> I can only describe it as "pressure". It's progressive. My wife notices it immediately and if you sit there a few minutes I end up with a naggin little pain and a ringing in my ear that lasts a while. With me, it's mostly the right ear and my wofe, the left. She sits on the left side of the couch and I'm on the right so it seems they are reflective sounds not direct, that's as close as I've come to isolating anything.
> 
> 
> I can't isolate a particular frequency. Since my last post, I've manageg to use the rta and the single band eq on one of my subs to get the bass pretty darn flat all the way up to 160. Sure I've got some 4 db swings in there but for a little placement experimentation and a single band parametric eq - not too bad.
> 
> 
> Problem now is, I got a replacement mic from my dealer to see if maybe that could be faulty, plugged it in and I get speaker detect errors. It's not emitting the test tones now. I'm beginning to think this is a buggy unit.



Got any A/V nut enthusiast friends that you could have over for a listen?


----------



## Artzilla




> Quote:
> Originally Posted by *pepar* /forum/post/16837940
> 
> 
> Got any A/V nut enthusiast friends that you could have over for a listen?



In my neighborhood, I'm that nut. The only other AV nut I know is my wife and she's had enough.


----------



## pepar




> Quote:
> Originally Posted by *Artzilla* /forum/post/16838042
> 
> 
> In my neighborhood, I'm that nut. The only other AV nut I know is my wife



Well somehow I knew you'd say that.







Where do you live?


----------



## Artzilla

Yeah, I'm the only nut who seems to care much at all about this in my circle of friends. I'm in West Boca just north of Fort Lauderdale.


----------



## glaufman

Well, that's a little far for me to trek to help out...


Have you tried putting the yamaha back in?


----------



## Artzilla




> Quote:
> Originally Posted by *glaufman* /forum/post/16839794
> 
> 
> Well, that's a little far for me to trek to help out...
> 
> 
> Have you tried putting the yamaha back in?



Thanks for the consideration regardless. Haven't put the Yamaha back in but I know what it will do. I've had it for years with the same rig. I know it and it's foibles in and out - thuis, my attempt at an upgrade. If I put it back in, I'll never get it back out unless it spontaneously combusts or something without a major battle ropyal woth my wife. Probably something worse than the one we're havign right now over it. I'm not whipped and my wife's not a B---h but this unit and I have just completely worn through her patience. She likes movies as much as I do and getting a pain in the ear every time you try to watch one doesn't contribute to fun or domestic tranquility.


----------



## Terry Montlick

Artzilla,


I am wondering if maxl (of whose msg I made a sarcastic and stupid remark







) may be correct.


You have open doors, which communicate to other rooms. So the effective size of your room is much larger. It is possible that the lowest room mode for this total space is infrasonic -- say, around 10 Hz. This is probably too low for your mic and electronics to measure. But even if your speaker/sub puts out a small amount of energy down there, it can be greatly amplified by the room mode if the total space is well sealed, and you are at one "end" of it.


Note that this "end" doesn't have to be at a linear extreme. Low frequency room modes happily bend around 90 degree angles, and do not have to be in a straight line. This is a common misconception in acoustics.


- Terry


----------



## Artzilla




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16839963
> 
> 
> Artzilla,
> 
> 
> I am wondering if maxl (of whose msg I made a sarcastic and stupid remark
> 
> 
> 
> 
> 
> 
> 
> ) may be correct.
> 
> 
> You have open doors, which communicate to other rooms. So the effective size of your room is much larger. It is possible that the lowest room mode for this total space is infrasonic -- say, around 10 Hz. This is probably too low for your mic and electronics to measure. But even if your speaker/sub puts out a small amount of energy down there, it can be greatly amplified by the room mode if the total space is well sealed, and you are at one "end" of it.
> 
> 
> Note that this "end" doesn't have to be at a linear extreme. Low frequency room modes happily bend around 90 degree angles, and do not have to be in a straight line. This is a common misconception in acoustics.
> 
> 
> - Terry



That sounds reasonable because my wife noticed it in the bedroom and the problem is detectable at the other end in the den. I have no doors, so I can't really test it. My subs are rated down to 20 & 25 hz in their native tune. I don't know what kind of rolloff there is below that. Your' theory holds water with me but the odd thing is that I get the same issue when running my mains only with EQ engaged (doesn't happen with no EQ & Mains only). They're B&W 803-s. Very capable, but I douby they're capable of putting out anything that low. I think they're rated to 39hz or something in that range.


----------



## glaufman




> Quote:
> Originally Posted by *Artzilla* /forum/post/16839808
> 
> 
> Thanks for the consideration regardless. Haven't put the Yamaha back in but I know what it will do. I've had it for years with the same rig. I know it and it's foibles in and out - thuis, my attempt at an upgrade. If I put it back in, I'll never get it back out unless it spontaneously combusts or something without a major battle ropyal woth my wife. Probably something worse than the one we're havign right now over it. I'm not whipped and my wife's not a B---h but this unit and I have just completely worn through her patience. She likes movies as much as I do and getting a pain in the ear every time you try to watch one doesn't contribute to fun or domestic tranquility.



Ca you at least put it "half in" so you can scan what it's outputting, and compare that to a similar scan of the Integra, so you can see if the Integra is putting anything out that could excite room modes that the Yamaha wasn't putting out?


Point being, unless I'm misunderstanding, you only made one change, the AVR, you didn't change the room setup, the speakers, the doors, acoustic treatments, etc...


So first step SHOULD BE to make sure the new component isn't doing anything funky... if it's not putting out test tones, it sounds like it's doing something funky... try a factory reset and/or firmware upgrade... you didn't buy it open box, did you?


----------



## Artzilla




> Quote:
> Originally Posted by *glaufman* /forum/post/16840632
> 
> 
> Ca you at least put it "half in" so you can scan what it's outputting, and compare that to a similar scan of the Integra, so you can see if the Integra is putting anything out that could excite room modes that the Yamaha wasn't putting out?
> 
> 
> Point being, unless I'm misunderstanding, you only made one change, the AVR, you didn't change the room setup, the speakers, the doors, acoustic treatments, etc...
> 
> 
> So first step SHOULD BE to make sure the new component isn't doing anything funky... if it's not putting out test tones, it sounds like it's doing something funky... try a factory reset and/or firmware upgrade... you didn't buy it open box, did you?



Certainly a sound approach but I think I've got one better in the works. Since Audyssey failed to initiate the test tones (confirmed by Kal the mic failure alone does not cause this) I have concluded with my dealer that I need a new unit as this one has at least one bug. (Audio that is. It also has the gamma bug on rgb video input) As opposed to beating my head agaisnt the wall with this one, I'm going to pick up a new unit (hopefully this afternoon) and beat my head against that one and see what happens.


----------



## glaufman




> Quote:
> Originally Posted by *Artzilla* /forum/post/16840729
> 
> 
> Certainly a sound approach but I think I've got one better in the works. Since Audyssey failed to initiate the test tones (confirmed by Kal the mic failure alone does not cause this) I have concluded with my dealer that I need a new unit as this one has at least one bug. (Audio that is. It also has the gamma bug on rgb video input) As opposed to beating my head agaisnt the wall with this one, I'm going to pick up a new unit (hopefully this afternoon) and beat my head against that one and see what happens.



Now ur talkin! Replacement under warranty, I presume?


----------



## Artzilla




> Quote:
> Originally Posted by *glaufman* /forum/post/16840750
> 
> 
> Now ur talkin! Replacement under warranty, I presume?



Yes, I picked it up at the end of April. I'm assuming any fault in the units would be a warranty replacement with it at 3 years and none of these units being that old yet but my dealer said even that was in question. Not by him, by Integra. I'm hoping this will solve this issue as well as the gamma bug. I had inquired about he gamma bug, even told him before I ordered it "make sure it doesn't have the gamma bug" and of course, it did. Integra, despite at least one memeber on this boards stating that he had the bug, and got a replacement which solved it, denies that they've hear dof it, that the problem exists. Whattcha gonna do?


----------



## glaufman

Um, me personally? That means I'm not going buy Integra. If you bought from an authorized dealer, there should be no question about the warranty if the new unit fixes the problem, and you haven't broken the warranty seal on the unit. Unless they claim it was just set up wrong, which is why we were saying to try a factory reset... and maybe a firmware upgrade... What is this gamma bug of which you speak?


----------



## Artzilla




> Quote:
> Originally Posted by *glaufman* /forum/post/16840872
> 
> 
> Um, me personally? That means I'm not going buy Integra. If you bought from an authorized dealer, there should be no question about the warranty if the new unit fixes the problem, and you haven't broken the warranty seal on the unit. Unless they claim it was just set up wrong, which is why we were saying to try a factory reset... and maybe a firmware upgrade... What is this gamma bug of which you speak?



I agree. That part is a no brainer. I'll refrain from commenting further because my dealer has always been a stand up guy and a complete overachiever in terms of service, (especially for someone on my budget given the scope ot their company) and he was reluctant to carry the line. He finally bent to pressure from outside sources and started carrying them. These were his comments on delaing with "a big Japanese company". Buyer beware I guess.


As for the gamma bug: If you feed the integra DHC 9.9 an rgb video signal via hdmi (don't know about component) and try to adjust the gamma, it only goes from green to red with negative & positive settings respectively. Change the signal from the same source (in my case the Pioneer BD-05) to a ycrbr 4:4:4, or 4:2:2 signal and the gamma adjustment works as it should.


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/16835387
> 
> 
> Using your file here is what i found:



That's actually quite excellent bacause the lowest modes are evenly spaced.



> Quote:
> what is this telling me about room treatments?



Nothing really. Mode calculators are meant to design new room dimensions, not advise how to treat an existing room. _All_ rooms need bass traps and absorption at the reflection points. This readout simply tells you that you're starting from a good place, so after treatment you'll end up better than other rooms with less favorable ratios.


--Ethan


----------



## CJO




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16841917
> 
> 
> That's actually quite excellent bacause the lowest modes are evenly spaced.
> 
> 
> 
> 
> Nothing really. Mode calculators are meant to design new room dimensions, not advise how to treat an existing room. _All_ rooms need bass traps and absorption at the reflection points. This readout simply tells you that you're starting from a good place, so after treatment you'll end up better than other rooms with less favorable ratios.
> 
> 
> --Ethan



How would you use a mode calculator for an L-shaped room? My room, for instance, has a relatively small (3'x5') alcove at the left rear corner of the room.


CJ


----------



## pepar




> Quote:
> Originally Posted by *CJO* /forum/post/16842059
> 
> 
> How would you use a mode calculator for an L-shaped room? My room, for instance, has a relatively small (3'x5') alcove at the left rear corner of the room.



You would not. Nor would it be used for my almost-but-not-quite rectangular room.


----------



## eiger

Hi All,


Long time AVSForum member, short-time "Acoustical Treatment" guy. I just recenly started putting the finishing touches on my room and have some moderate room challenges, that I'd like some advice on.


Room is 26 x 16. Below are some pictures that show my setup and some of the challenges. Room configuration is set up for 7.1. Fairly deep. There is an area to the left of the viewing area that is a fairly open space. Don't know how much sound is escaping here. What I DO KNOW, is that when I clap my hands, there is an echo coming from that area.


Please do not tell me to build a wall. Not really an option. Anyone have ideas of what I can do in terms of other treatments and panels tho?


Feedback welcome. Thx!


----------



## Terry Montlick

eiger,


Your room appears to have no soft, acoustically absorptive surfaces other than the furniture. The rug, while well placed, seems too thin to do much of anything. This makes for way too "live" a space.


Get several 2" thick acoustic panels, and spread them around the walls just about anywhere (though don't fix them permanently, so that they can be moved later). Don't worry about bass traps or covering first reflection points just yet. Your room has more fundamental issues!


- Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *eiger* /forum/post/16845177
> 
> 
> Anyone have ideas of what I can do in terms of other treatments and panels tho?



Besides Terry's always-good advice, I suggest you move some of the stuff that's now in corners and put bass traps there. A room like that needs at least four bass traps, and even more is advisable. Music is much more than just mid and high frequencies, and the entire range needs to be treated including bass frequencies. As a point of reference, I have 51 panels in my 25 by 16 foot living room home theater. You don't need that many for great sound! But you definitely need more than what you have now.










--Ethan


----------



## nathan_h




> Quote:
> Originally Posted by *eiger* /forum/post/16845177
> 
> 
> Please do not tell me to build a wall. Not really an option. Anyone have ideas of what I can do in terms of other treatments and panels tho?



If this were my room, I'd do two things:


1) 4 or 6 inch thick panel traps straddling each corner, floor to ceiling if possible, to help the bass response.


2) 2 or 4 inch think wall panels at the first reflection points -- though as noted above, throwing them anywhere in the room would be useful given the current situation.


Here's a good read: http://www.realtraps.com/art_room-setup.htm 


You are on the right track, with your thinking that you need acoustic panels. And the advice in the two posts above will get you a long way towards a solution.


--


By the way, that's a nice space you have to work with.


----------



## paranormalg35

hi guys. received my panels from ATS they are the micro suede ones in wine color.


questions


o i have these in the right place? want to make sure before i put them up... cause its a pain in the ass


----------



## pepar




> Quote:
> Originally Posted by *paranormalg35* /forum/post/16848162
> 
> 
> hi guys. received my panels from ATS they are the micro suede ones in wine color.
> 
> 
> questions
> 
> 
> o i have these in the right place? want to make sure before i put them up... cause its a pain in the ass



Are you asking if they look good there or if they are helping your room acoustics 'cause they are totally different questions.


----------



## KERMIE

A friend of mine has a few of these DIY base traps that he made for the corners of his room and 2 on the sides of his room. they are about 54" tall and 21 " wide covering in black fabric. Do you think these are effective for Bass Traps?


----------



## nathan_h




> Quote:
> Originally Posted by *paranormalg35* /forum/post/16848162
> 
> 
> 
> do i have these in the right place? want to make sure before i put them up... cause its a pain in the ass



No. http://www.realtraps.com/art_room-setup.htm though it looks like you'll have trouble placing them in the most effective spots. So what you've chosen may be best.


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/16849705
> 
> 
> Do you think these are effective for Bass Traps?



They probably help some, but that doesn't look to me like a particularly good way to make a bass trap.


--Ethan


----------



## tleavit

Installed my ceiling panels. Did the old laser pointer / mirror trick to get the exact location to all 3 front speakers.











Reran Audyssey


----------



## krasmuzik

tleavit


there is no way those LCRs are capable of 20Hz and even if they play at 80Hz it is probably with more distortion/compression than your sub. Set them to small or whatever your receivers equivalent is. Usually 'full band' is called 'large' - but 'full band' is actually a better name because this is a crossover control. What it means is all of the frequencies are sent to the LCRs with none of them sent to the sub - in other words - these frequencies are either not played at all because they are below your LCR range or they are not played well at all because the sub can do better. And if I misunderstand and "full band" means the sub shares the bottom octaves of the LCR's - then the latter comment still applies.


It does requiring properly balancing sub and LCR levels - do it right a plucked bass will sound like it is on the LCR stage even though the fundamental is played by the sub.


Also a panel above the screen and some black velvet on the white case will seriously cut back on the ceiling glare - may not think it is distracting now - but you will realize it was once you fix it!


----------



## pepar




> Quote:
> Originally Posted by *tleavit* /forum/post/16853910
> 
> 
> 
> Reran Audyssey



I know this is not what you're on this thread for, but you did change your speakers - ALL of them - from Full Band to a crossover around 80Hz, didn't you?


----------



## tleavit




> Quote:
> Originally Posted by *pepar* /forum/post/16854434
> 
> 
> I know this is not what you're on this thread for, but you did change your speakers - ALL of them - from Full Band to a crossover around 80Hz, didn't you?



Yup! I usually change them right back to the Onkyo 805's THX recomendation of 80. I had just taken those raw pictures right after I ran it. I find it funny that *every* time I run Aud, it sets them back to Full and drops my Sub WAY down. In this cae, it wasn't as bad, in times before it would go like -20db to -25db on my sub.


----------



## tleavit




> Quote:
> Originally Posted by *krasmuzik* /forum/post/16854423
> 
> 
> Also a panel above the screen and some black velvet on the white case will seriously cut back on the ceiling glare - may not think it is distracting now - but you will realize it was once you fix it!



Thanks! Hahahah, thats been on my wifes "to do list" for 1.5 years now!


----------



## krasmuzik

You could threaten to use her sewing machine and make a case wrap yourself - that will get her motivated to do it soon as she sees you start threading the bobbin - cause you will be doing it all wrong!


So Audyssey sets it up wrong by default?!


----------



## tleavit




> Quote:
> Originally Posted by *krasmuzik* /forum/post/16858884
> 
> 
> You could threaten to use her sewing machine and make a case wrap yourself - that will get her motivated to do it soon as she sees you start threading the bobbin - cause you will be doing it all wrong!
> 
> 
> So Audyssey sets it up wrong by default?!



Ya, every time sets my speakers to full since I bought it 2 years ago.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *krasmuzik* /forum/post/16858884
> 
> 
> So Audyssey sets it up wrong by default?!





> Quote:
> Originally Posted by *tleavit* /forum/post/16858901
> 
> 
> Ya, every time sets my speakers to full since I bought it 2 years ago.



Fine point: Audyssey measures the response. It is the decision of the particular AVR/prepro manufacturer to define a specific FR as full and that varies a lot from one to another. The Audyssey EQ (one of the stand-alone units) is more reasonable, imho, in making this determination.


----------



## djakes

I've read through the choices regarding sound proofing soffits and dead vent systems (thanks John H.). But I was wondering if I would get decent isolation if I built a backer box around the HVAC vent (similar to what is used with recessed lights, but with DD + GG, and not cement board)?


I would load up the gap between the flex duct and backer box with Silenseal or similar. The remainder of the duct work would be behind DD+GG. Sound would still travel down the duct, but I'll try to S shape it to reduce the reflections.


Thoughts?


----------



## Artzilla




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16839963
> 
> 
> Artzilla,
> 
> 
> I am wondering if maxl (of whose msg I made a sarcastic and stupid remark
> 
> 
> 
> 
> 
> 
> 
> ) may be correct.
> 
> 
> You have open doors, which communicate to other rooms. So the effective size of your room is much larger. It is possible that the lowest room mode for this total space is infrasonic -- say, around 10 Hz. This is probably too low for your mic and electronics to measure. But even if your speaker/sub puts out a small amount of energy down there, it can be greatly amplified by the room mode if the total space is well sealed, and you are at one "end" of it.
> 
> 
> Note that this "end" doesn't have to be at a linear extreme. Low frequency room modes happily bend around 90 degree angles, and do not have to be in a straight line. This is a common misconception in acoustics.
> 
> 
> - Terry



I think you hit it Terry, or at least part of it. I'm dead center of the total space and found that I can feel it in my office even running just the mains - no sub. O got a tripod and I'm moving the seating are froward and trying variable mic positions at Chris's suggestion and different sub placements (again) with the doors to 2 of the rooms closed to see what I get.


----------



## BlakeN

Sorry if this has been asked before but after reading +50 pages and some searching my eyes are killing me.


Does anyone have any links to lower wall treatment construction using something like Insul-Shield?


I am not familiar with that material can you just cover it in GOM or does it need a frame.


Thanks


----------



## Ethan Winer

However you can get absorbing materials in the right places is fine. But covering the very bottom of the side walls is not useful unless you're using very thick materials. In that case you're making bass traps, not reflection absorbers.


Reflections occur at specific places, and those are where the treatment should go. Much more here:

Early Reflections 
How to set up a room 


--Ethan


----------



## KERMIE

Ethan,


Is really the main reason for NOT doing the bottom half is the risk of making the room too dead or is there much more at risk here?


----------



## Ethan Winer

^^^ Well, mostly it's just a waste because little sound reflects off the walls down that low.


However, I prefer a room to be more toward dead anyway, at least if the room is on the small side. Small room ambience sounds pretty bad, and it covers up the good larger ambience that's generally present in good recordings. So for a room the size you'll find in most homes, having it on the dead side actually makes the music sound larger and more lifelike.


--Ethan


----------



## allredp




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16882824
> 
> 
> However, I prefer a room to be more toward dead anyway, at least if the room is on the *small side. Small room* ambience sounds pretty bad, and it covers up the good larger ambience that's generally present in good recordings. So for *a room the size you'll find in most homes*, having it on the dead side actually makes the music sound larger and more lifelike.
> 
> 
> --Ethan



Hey Ethan,


Great help as usual!


Could you give some parameters of "small" rooms?


My room is 27' x 15' x 8' - does that qualify for small?


Thanks much.


----------



## pepar




> Quote:
> Originally Posted by *allredp* /forum/post/16882927
> 
> 
> Hey Ethan,
> 
> 
> Great help as usual!
> 
> 
> Could you give some parameters of "small" rooms?
> 
> 
> My room is 27' x 15' x 8' - does that qualify for small?
> 
> 
> Thanks much.



"a room the size you'll find in most homes"


----------



## Dennis Erskine




> Quote:
> Could you give some parameters of "small" rooms?



If you move 2' and the sound changes, it's a small room. Your room will be a small room.


----------



## Franin




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16882824
> 
> 
> ^^^ Well, mostly it's just a waste because little sound reflects off the walls down that low.
> 
> 
> However, I prefer a room to be more toward dead anyway, at least if the room is on the small side. Small room ambience sounds pretty bad, and it covers up the good larger ambience that's generally present in good recordings. So for a room the size you'll find in most homes, having it on the dead side actually makes the music sound larger and more lifelike.
> 
> 
> --Ethan



I was just going to ask the same question regarding making a room dead. My bottom half of the wall has Carpet and Underlay which is divided by skirting( actually it was more aesthetic purposes). I have the room treatments in place which were placed by a certified HAA ( these guys specialize in room treatments and room calibrations over here in Western Australia). I was going to cover the top half of the walls with Acoustic wall tiles to deadned the room. Do you think that is wise decision or is there other products to use.


These are ones im talking about:


> Quote:
> Fonic Acoustic Tiles are specially designed and tested to improve the frequency response and decay time of mid to high frequencies in Recording Studios, Home Theatres and Public spaces. They are typically used on walls and ceilings at reflection points to reduce interference and flutter echoes.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Franin* /forum/post/16885815
> 
> 
> My bottom half of the wall has Carpet and Underlay ... I was going to cover the top half of the walls with Acoustic wall tiles to deadned the room.



That's not a good idea because you don't want or need to make all of the walls absorbent. Not only is that much surface coverage not a good idea, but the materials you propose are not thick enough. The general goal in room treatment is to have decay times that are more or less uniform across the audible range. Thin materials absorb only higher frequencies. So the room is too dead sounding _and_ the bass still rattles around and is boomy etc. The graph below is from my recent video Hearing is Believing , showing how extensive diffusion, coupled with absorption, helps make the decay times more uniform.


--Ethan


----------



## Dennis Erskine

Ethan is not entirely correct, nor is he entirely incorrect either. There are two purposes for the use of absorption in a playback space. One is to solve direct acoustical issues. For example, SBIR when speakers are near a boundary, back reflections from an AT screen, or, in some cases, to knock down the effect of early reflections (usually diffusion is more useful). In this case, the placement of the absorptive treatments becomes part and parcel of their performance.


The second reason is to reduce the overall reverberation time in the room. In this case, the position of the absorptive material is less important than its very presence in the room. For this purpose, ear height and below would work.


In actual practice, you may absolutely want absorptive materials to stay out of early reflection points. An example would be the use of diffusors to expand sound stage width, depth or to enhance the surround channels. At the same time, absorption needs to be placed in the room to reduce reverberation time. This would be a real case where absorptive panels in less than obvious locations is required.


----------



## Franin




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16886712
> 
> 
> That's not a good idea because you don't want or need to make all of the walls absorbent. Not only is that much surface coverage not a good idea, but the materials you propose are not thick enough. The general goal in room treatment is to have decay times that are more or less uniform across the audible range. Thin materials absorb only higher frequencies. So the room is too dead sounding _and_ the bass still rattles around and is boomy etc. The graph below is from my recent video Hearing is Believing , showing how extensive diffusion, coupled with absorption, helps make the decay times more uniform.
> 
> 
> --Ethan



Thank you for your response I will leave it as it is then.


----------



## allredp




> Quote:
> Originally Posted by *pepar* /forum/post/16884713
> 
> 
> "a room the size you'll find in most homes"



Caught that in Ethan's original post, but wondered if there were some general parameters for "small" like cubic feet, etc. But, thanks for the reply.











> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16885810
> 
> 
> If you move 2' and the sound changes, it's a small room. Your room will be a small room.



Ah, that makes sense in practice. It is true, at least of bass in my room.










Thanks for the clarifications, though I'm still curious if there are some numbers to put to "small" or "large" which would help establish whether a room should be damped-down vs. left more natural.


----------



## nathan_h

When talking about acoustics: Large room = concert hall.


Small room = anything you'd find in a home, even a McMansion.


----------



## KERMIE

Two Questions:


1. What makes a good "membrane" to cover corner bass traps in the rear


2. Why do you use it on the bottom of walls (like FSK)?


----------



## erkq




> Quote:
> Originally Posted by *nathan_h* /forum/post/16889270
> 
> 
> When talking about acoustics: Large room = concert hall.
> 
> 
> Small room = anything you'd find in a home, even a McMansion.



Ha, ha! Not always. I had a buddy (lifestyles too different to maintain friendship) who build a 3 story concert hall with a replica of some old-school European pipe organ as part of his ranch house. It was the darndest thing to walk from a nice, but definitely NOT McMansion house into this incredibly ornate concert hall. Stanford used his facilities for a while after the Loma Prieta earthquake damaged their organ recital hall.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/16890585
> 
> 
> Ha, ha! Not always. I had a buddy (lifestyles too different to maintain friendship) who build a 3 story concert hall with a replica of some old-school European pipe organ as part of his ranch house. It was the darndest thing to walk from a nice, but definitely NOT McMansion house into this incredibly ornate concert hall. Stanford used his facilities for a while after the Loma Prieta earthquake damaged their organ recital hall.



Well now, that *would* be a concert hall then, wouldn't it?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16886782
> 
> 
> The second reason is to reduce the overall reverberation time in the room. In this case, the position of the absorptive material is less important than its very presence in the room. For this purpose, ear height and below would work.



Good point Dennis, ands this brings up a related issue. In my experience treating "normal" furnished rooms, there's less need for overall reverb reduction. Once absorption has been placed at the reflection points, and in corners for bass trapping, that's often enough. But you are correct that all treatment is not necessarily position-specific.


--Ethan


----------



## allredp




> Quote:
> Originally Posted by *nathan_h* /forum/post/16889270
> 
> 
> When talking about acoustics: Large room = concert hall.
> 
> 
> Small room = anything you'd find in a home, even a McMansion.



Well I certainly don't have a McMansion, eh! Thanks.


----------



## Weasel9992




> Quote:
> Originally Posted by *allredp* /forum/post/16888481
> 
> 
> Caught that in Ethan's original post, but wondered if there were some general parameters for "small" like cubic feet, etc. But, thanks for the reply.



Everest says 2500Ft3. Dennis' answer was the right one from a practical standpoint though.


Frank


----------



## eiger

All -


Does anyone have experience with the panels from Ready Acoustics? Quality?


On their website I see "ReadyTraps" panels and "Chamelon C2" panels. Both of these are for mid to high frequencies. The ReadyTraps are significantly cheaper and looks like you can get a bundle.


Anyone know the differences between these models? I'm looking to address my side and front walls so guessing this is the right area I need to be looking if I'm not planning DIY components.


Posted my room configuration a couple pages back. Thx!


----------



## nathan_h




> Quote:
> Originally Posted by *eiger* /forum/post/16901466
> 
> 
> All -
> 
> 
> Does anyone have experience with the panels from Ready Acoustics? Quality?
> 
> 
> On their website I see "ReadyTraps" panels and "Chamelon C2" panels. Both of these are for mid to high frequencies. The ReadyTraps are significantly cheaper and looks like you can get a bundle.
> 
> 
> Anyone know the differences between these models? I'm looking to address my side and front walls so guessing this is the right area I need to be looking if I'm not planning DIY components.
> 
> 
> Posted my room configuration a couple pages back. Thx!





After reviewing the test data and materials from both, I compared the price of the roughly equivalent models from Ready Acoustics and GIK Acoustics and chose GIK. Before I completed my purchase, however, I took them up on their offer of a free phone consultation to discuss my room and needs (based on photos I sent them). That was very helpful in terms of getting the most impact for the limited budget I had.


But Ready Acoustics has some DIY options, and some construction methods that GIK doesn't offer. So it's not a easy question to answer.


I've also used Real Traps in my room and found the construction/fit/finish to be superior to the competition. It was, however, a little too "industrial" looking for the lady of the house. If you factor in re-sale value, and/or like the solid look, Real Traps is worth considering.


I think all of these (and some other) reputable brands will give you good results, if you intelligently choose which products you buy, and if you carefully select their placement in your home for the right impact.


----------



## Ictusbrucks




> Quote:
> Originally Posted by *erkq* /forum/post/16785193
> 
> 
> Prices are very approximate... from memory... just to give you an idea. This stuff is pretty cheap.
> 
> 
> I use:
> 
> 
> 1. Room EQ Wizard is free and GREAT! I run it on Windoze.
> 
> 
> 2. LinearX M31 calibrated mic. Comes with it's calibration curve you can enter into Room EQ Wizard if you want. About $100
> 
> 
> 3. Behringer MiniMIC modeling mic pre-amp. I don't use any of the modeling settings, of course. It was just a nice cheap mic pre-amp with an analog VU meter. It's good to 6Hz! About $89
> 
> 
> 4. Then I got an M-Audio Transit to get the pre-amp output into the laptop's USB port and Room EQ Wizard's test tones into the audio system. About $50
> 
> 
> 5. Last, I use Behringer's Feedback Destroyer Pro to adjust out those bothersome "humps". It's a multi-band parametric eq that works extremely well for tuning sub-woofers. About $99




Hi erkq/Pepar,


Sorry to bug you about this again but I just finally ran some measurements last night with my Galaxy CM140 SPL meter and REW using my Laptop.


Unfortunately my laptop only has a Mic in... no line in. So I dont thinnk the curves I got mean much, as its only saying ~45-50db until I hit the 1khz range, then it gets to the 75db area. And this is with my subwoofer turned up to room-shaking levels. And I did calibrate things to the proper level beforehand.



But I am still confused about what the M-Audio Transit does. In the quoted post you said you're going Mic-Preamp-> Transit -> USB.


So would the M-Audio transit allow me to bypass the laptops soundcard somehow? Or do I need to lug down my desktop machine to get a line input?


What Pepar said in this post seems to contradict what erkq said:



> Quote:
> Technically, no actually, you are using the line in and line out of the "soundcard." The mic's preamp does not pug into a mic input; it goes into the line input. Line output goes to the device/channel being tested.


----------



## pepar




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16908103
> 
> 
> Hi erkq/Pepar,
> 
> 
> Sorry to bug you about this again but I just finally ran some measurements last night with my Galaxy CM140 SPL meter and REW using my Laptop.
> 
> 
> Unfortunately my laptop only has a Mic in... no line in. So I dont thinnk the curves I got mean much, as its only saying ~45-50db until I hit the 1khz range, then it gets to the 75db area. And this is with my subwoofer turned up to room-shaking levels. And I did calibrate things to the proper level beforehand.
> 
> 
> 
> But I am still confused about what the M-Audio Transit does. In the quoted post you said you're going Mic-Preamp-> Transit -> USB.
> 
> 
> So would the M-Audio transit allow me to bypass the laptops soundcard somehow? Or do I need to lug down my desktop machine to get a line input?
> 
> 
> Thanks!
> 
> Ryan



I picked up an M-Audio MobilePre USB on ebay for ~$80. Not familiar with the Transit, but a quick visit to their site suggests that it might work. With the stereo line in and stereo line out - as opposed to discrete connectors for each channel - you need to look at your 3-pole-to-whatever adapter to make sure that you are using the same channel for both in and out.


Yes, any measurements you made with your laptop sound are throwaways.







Onboard laptop audio solutions lack the necessary bi-directionality which is why external "soundcards" are needed. I know that there are Firewire interface units, but most use USB. Firewire is more "pro" and that usually means it is more sophisticated and more $$$.


If you are using a mic preamp in addition to the USB soundcard, the mic preamp needs to plug into a line input. One of the reasons I bought the MobilePre USB is so that I could plug a mic into the mic input and do away with the mic's preamp. I've just learned that I am not supposed to do that, but that is another subject entirely and is unrelated to your question.


----------



## Ictusbrucks




> Quote:
> Originally Posted by *pepar* /forum/post/16908161
> 
> 
> With the stereo line in and stereo line out - as opposed to discrete connectors for each channel - you need to look at your 3-pole-to-whatever adapter to make sure that you are using the same channel for both in and out.




Thanks for the reply.


Do you mean making sure that both in/out are using L or R??


I am planning on doing everything at just 1/8" mini. I have a Mini-to-RCA cable so I have separate L and R cables going into the receiver.


Do you still think I need a separate adapter or could I just reverse the RCA cables if it doesn't work? And to be clear, is this a 'works or doesn't work' thing, or are we talking about innacurate measurements?


Also not sure exactly what a 3-pole adapter is, I couldn't find it on google, only standard Y adapters. Are you talking about something that would separate stereo into separate L/R channels? Do they even make that for mini?


----------



## Ictusbrucks




> Quote:
> Originally Posted by *pepar* /forum/post/16908161
> 
> 
> If you are using a mic preamp in addition to the USB soundcard, the mic preamp needs to plug into a line input.





Nope, no preamp for me since I am using an SPL meter... Am I confused? Do I still need a preamp with a Galaxy Cm140 SPL meter?


----------



## pepar




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16908192
> 
> 
> Thanks for the reply.
> 
> 
> Do you mean making sure that both in/out are using L or R??
> 
> 
> I am planning on doing everything at just 1/8" mini. I have a Mini-to-RCA cable so I have separate L and R cables going into the receiver.
> 
> 
> Do you still think I need a separate adapter or could I just reverse the RCA cables if it doesn't work? And to be clear, is this a 'works or doesn't work' thing, or are we talking about innacurate measurements?
> 
> 
> Also not sure exactly what a 3-pole adapter is, I couldn't find it on google, only standard Y adapters. Are you talking about something that would separate stereo into separate L/R channels? Do they even make that for mini?



For using measuring software like REW, pick Left or Right, and use that channel's input and that channel's output. If you have mono 1/8" minis, then they will only use one of the channels - I forget if it is left or right - so you won't need to do anything else but plug in. If your minis go to left and right RCA phono plugs, you do need to pick a channel to use.


Mono 1/8" minis are 2-pole ("tip-and-sleeve" in old jargon - two circuits, one hot and one ground), stereo minis are 3-pole ("ring, tip-and-sleeve" - three circuits, one left, one right and one ground).


----------



## pepar




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16908213
> 
> 
> Nope, no preamp for me since I am using an SPL meter... Am I confused? Do I still need a preamp with a Galaxy Cm140 SPL meter?



Then you have a line level output and need to plug into a line level input. There is a preamp built into the SPL meter.


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/16902964
> 
> 
> I've also used Real Traps in my room and found the construction/fit/finish to be superior to the competition. It was, however, a little too "industrial" looking for the lady of the house. If you factor in re-sale value, and/or like the solid look, Real Traps is worth considering.



Thanks very much Nathan. In case you're not aware, we have some newer products that are more "spouse friendly" than our usual panels, including a bass traps disguised as a large planter.


--Ethan


----------



## Ictusbrucks

Just FIY: I got the Creative SB X-Fi USB soundcard and worked with REW without even installing the drivers. It was the only decent one that BestBuy had in stock so I took a chance and it seems fine.


It didn't specify whether it was full duplex or not, but it did work with REW. However, my baby daughter was sleeping so I had to do the measurement at super-low-volume. Even so, the results look better than before using the laptop's mic input. I'll probably have to wait until this weekend to take measurements at the right volume though.


----------



## KERMIE

My neighbor insists that these louvered shutters from an old barn house that was torn down work very well as diffusers.


he has about 8-10 of them across the back half of the room on his ceiling and back wall. They are on top of 1" rigid fiberglass and all covered in black GOM. I have not been in a room of his size with or without them to compare. I think it sound good but...


he used them because they were free and it only took up 2" of total depth


every other one is opened (angled) forward/backward, up/down depending on ceiling or back wall.











any thoughts


----------



## nathan_h

Better than a bare wall, ie, better than not having them. But more depth, varied depth, and varied slant would be even better.


----------



## pepar




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/16910861
> 
> 
> Just FIY: I got the Creative SB X-Fi USB soundcard and worked with REW without even installing the drivers. It was the only decent one that BestBuy had in stock so I took a chance and it seems fine.
> 
> 
> It didn't specify whether it was full duplex or not,



It is.


----------



## allredp




> Quote:
> Originally Posted by *Weasel9992* /forum/post/16901138
> 
> 
> Everest says 2500Ft3. Dennis' answer was the right one from a practical standpoint though.
> 
> 
> Frank



Ah, that's helpful, Frank. Thanks much...


----------



## tourkala

Hi,


Does anyone know what type of screws to use with Isomax? I am doing a ceiling sound isolation and already nailed 1/8"MLV to the joists. Now it is time to screw the hat tracks with Isomax clips but I cannot figure out which screw to use for the clips and for the sheetrock.. I will have two layers of Type C Gypsum Board. One is 1/2 inch, the other is a 5/8

Thanks


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/16911147
> 
> 
> My neighbor insists that these louvered shutters from an old barn house that was torn down work very well as diffusers.



I wonder if he's ever actually heard real diffusors.











Ask your neighbor to look at this video:

All About Diffusion 


Then, if he's capable of recording things, ask him to do a similar test and assess what he hears. My guess is his louvers will sound more like the bare wood partition than the QRD diffusor.


--Ethan


----------



## snudley

Hey,


I'm keep wanting to pick up a box of the Certainteed Acoustaboard tiles that marc_stan advertises on the forum, but can't convince myself to do it.


Has anyone tried using these tiles for wall applications at reflection points? They aren't the most attractive things out there, but are definitely more in line with my budget. I would like to know if they can be wrapped in cloth of my choosing and possibly trimmed on the edges to create a bevel of sorts.


Thanks,


snudley


----------



## KERMIE




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16915227
> 
> 
> I wonder if he's ever actually heard real diffusors.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Ask your neighbor to look at this video:
> 
> All About Diffusion
> 
> 
> Then, if he's capable of recording things, ask him to do a similar test and assess what he hears. My guess is his louvers will sound more like the bare wood partition than the QRD diffusor.
> 
> 
> --Ethan




If you only have 2 inches to work with on the back wall (maybe 3) what would be the best solution for diffusion


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/16917563
> 
> 
> If you only have 2 inches to work with on the back wall (maybe 3) what would be the best solution for diffusion



A three-inch deep diffusor is better than a bare wall. But it depends on the distance from the listener's head to that wall. If it's like a foot or less I'd probably use absorption instead of diffusion.


--Ethan


----------



## KERMIE




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/16921196
> 
> 
> A three-inch deep diffusor is better than a bare wall. But it depends on the distance from the listener's head to that wall. If it's like a foot or less I'd probably use absorption instead of diffusion.
> 
> 
> --Ethan



The back row will be about 2 feet and the first row will be about 7 feet. There will not be many times the back row will be filled with people though..


There are also rear surround speakers in back on a 12 foot wide wall


----------



## Ethan Winer

^^^ In that case a diffusor six inches deep would be fine.


--Ethan


----------



## KERMIE

Ethan,


is something like this effective above the first reflection and seating area of a "small" room. (12x18)


----------



## nathan_h

I'm not Ethan but here's the general idea: Depending on what the material actually is, and how thick it is, and the relation to the speakers and seats, it could be a good absorption method.


----------



## tony123

I'm curious about how my room is responding to base. Room is 30x17.5x9' so I have 4725 cubic feet.


I have a 15" servo Velodyne and a 15" Klipsch sub. After moving them all over the room, I ended up with them both as end tables to my middle row and firing forward into the room. I'm getting what I might call "almost resonable performance" whatever that is.










I have a preference for above average base and just can't accomplish it in this room with the equipment I have.


The room is unfinished. It is sheetrocked and has linacoustic down the side walls and on the full screen wall. It also has 703 triangular base traps in both the front corners, floor to ceiling. However, the ceiling is not yet sheetrocked. So the ceiling is open rafters that have insulation in them. The insulation is roughly 6" thick then there is 12" or so of air space and then the subfloor for the main level of the house. I got to thinking that the entire ceiling is currently very much like a large base trap...isn't it?


So my question is: Am I just traping all the base in the ceiling? or at least enough of it to take the "umph" out of my subs?


I'm fishing for some reassurance that sheetrocking the ceiling is going to make a difference for me.


Thanks for any input.


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/16931017
> 
> 
> is something like this effective above the first reflection and seating area of a "small" room. (12x18)



You bet. That photos shows the ceiling in my home studio, and I have something similar in my 25 by 16 living room.


--Ethan


----------



## Dan Woodruff




> Quote:
> Originally Posted by *tony123* /forum/post/16933664
> 
> 
> I'm curious about how my room is responding to base. Room is 30x17.5x9' so I have 4725 cubic feet.
> 
> 
> I have a 15" servo Velodyne and a 15" Klipsch sub. After moving them all over the room, I ended up with them both as end tables to my middle row and firing forward into the room. I'm getting what I might call "almost resonable performance" whatever that is.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have a preference for above average base and just can't accomplish it in this room with the equipment I have.
> 
> 
> The room is unfinished. It is sheetrocked and has linacoustic down the side walls and on the full screen wall. It also has 703 triangular base traps in both the front corners, floor to ceiling. However, the ceiling is not yet sheetrocked. So the ceiling is open rafters that have insulation in them. The insulation is roughly 6" thick then there is 12" or so of air space and then the subfloor for the main level of the house. I got to thinking that the entire ceiling is currently very much like a large base trap...isn't it?
> 
> 
> So my question is: Am I just traping all the base in the ceiling? or at least enough of it to take the "umph" out of my subs?
> 
> 
> I'm fishing for some reassurance that sheetrocking the ceiling is going to make a difference for me.
> 
> 
> Thanks for any input.






Yes, sheet rock on the ceiling will make a difference. You also need to remember that you don't have the door in place yet.


Something I learned when placing my subs is to start at opposite corners measuring out 1/5 or 1/3 the length of the room and about 8 inches from the wall.


----------



## Ethan Winer




> Quote:
> Originally Posted by *tony123* /forum/post/16933664
> 
> 
> Am I just traping all the base in the ceiling? or at least enough of it to take the "umph" out of my subs?



You might misunderstand the principle. Bass traps generally _increase_ the perceived level of bass in a room because they absorb the reflections that cause nulls.



> Quote:
> I'm fishing for some reassurance that sheetrocking the ceiling is going to make a difference for me.



Adding sheet rock will likely make the sound worse because you'll be covering whatever amount of absorption you have now. So then you'll need to add more absorption under the sheet rock.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *tony123* /forum/post/16933664
> 
> 
> So my question is: Am I just traping all the base in the ceiling? or at least enough of it to take the "umph" out of my subs?



While you're unfinished ceiling probably is making a difference, it's probably making a positive impact and not a negative one. Bass trapping won't have a subtractive effect on low end the way you're thinking it will; it will even out the peaks and bring up the valleys some, but it's never going to turn a +10 peak into a -10 valley no matter what you do.


I think the lack of bass response really has more to do with the size and shape of the room itself...you may just need more bass trapping. I don't know that putting up sheet rock is going to "help" at all. It'll just create another hard, reflective surface...you're almost certainly getting better low end response with the unfinished ceiling than you would with a 9' sheet rock ceiling or something.


Frank


----------



## tony123

Ethan, Dan, Frank, thanks for the input. I suppose I don't understand exactly what's happening. But I do trust in what you guys have to say.


So assuming I get the room finished you're saying that adding more bass trapping may start to help?


Will dropping some cash on a volkswagon sized sub help !?!?! I'd be willing to do something like a Danley, Submersive or Ed A7-900 Of course, after treating the room. I was starting to wonder if something like that was needed for my size room anyway.


----------



## Ethan Winer




> Quote:
> Originally Posted by *tony123* /forum/post/16941889
> 
> 
> you're saying that adding more bass trapping may start to help?



Yes, of course. Not sure how deeply you want to get into this, but there are a ton of non-sales articles and videos on my company's site that explain all aspects of small room acoustics:

RealTraps Articles 
RealTraps Videos 



> Quote:
> Will dropping some cash on a volkswagon sized sub help !?!?!



Maybe, but it will not help as much as finding the correct acoustic solution.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *tony123* /forum/post/16941889
> 
> 
> So assuming I get the room finished you're saying that adding more bass trapping may start to help?



The corners were the right start, but the back wall can be the culprit for some of the deepest nulls and highest peaks in the room. Some more trapping in the right places will probably help.


Frank


----------



## mhdiab

This thread spans 6 years and 170 pages which is cool. However, it is becoming harder and harder to find a good summary of things that are must do's and things that are good to do. Does anyone have a link to something good like that?


For me - the HT has to be up and running within a month... The room is there, dry-walls are in and paint is in. Cut-outs are there for the speakers. Those things aren't getting moved now. Speakers might move in the future.


What I am doing next is putting up a false wall up front to put the screen on. What I got from the first post here is to cover the

FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling


I guess this still stands correct 7 years later


Then I put the false wall up in front of that. put in the speakers and frame around them. Around that I have been told to put Guilford acoustical fabric.


Everything after this point can be altered going forward. I can put the panels on the sides up etc. So considering that I have an existing room with carpet is there something else that "isn't to late" but that I really should do before I do anything else?


Thanks!


----------



## tony123

Thanks Ethan / Frank. Since my posting I've borrowed a second sub and it has gone a long way to solving my issues. In fact, I'm quite pleased except for the middle two seats in my front row. There is a terrible null right in that location. I'm going to get further along in construction and then revisit the acoustic treatment. I'm open to adding base traps in the rear of the room, and have the place for them.


Right now the placement of both subs is in the middle of the room as end tables to the middle row. My "master plan" was to have them behind the AT screen, but that's just not giving me the performance I want. At least not with my current treatments.


----------



## Terry Montlick




> Quote:
> Originally Posted by *mhdiab* /forum/post/16958430
> 
> 
> What I am doing next is putting up a false wall up front to put the screen on. What I got from the first post here is to cover the
> 
> FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling
> 
> 
> I guess this still stands correct 7 years later



Sometimes.










I find that there is no "one size fits all" treatment plan. Sometimes I use an absorptive front wall and sometimes I don't. The requirements of different rooms vary.


An important goal for any room treatment is to achieve relatively uniform reverberation times (RT60s) over the major range of audio frequencies. Traditionally in architectural acoustics, the classic Sabine or Eyring equation is used for prediction. Here is a calculator for this purpose written by Chris Whealy:
http://www.whealy.com/acoustics/ControlRoom.html 


I favor the more modern (but difficult) ray tracing method, which requires building a 3D CAD model.


Of course, many people just make a guess at room treatment.

















- Terry


----------



## mhdiab

Terry


Thanks for the post that is a really neat calculator. I am guessing Wall 1 is the front wall -- correct? Came up with


User defined absorbant wall surface

Plasterboard on frame

50% each


Not even sure what to do with that information - lol


----------



## CJO




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16959479
> 
> 
> I favor the more modern (but difficult) ray tracing method, which requires building a 3D CAD model.
> 
> 
> Of course, many people just make a guess at room treatment.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> - Terry



Is there any low-cost (or free) software that does the ray tracing method? Is an AutoCAD 3D model sufficient?


Thanks,

CJ


----------



## Kal Rubinson




> Quote:
> Originally Posted by *CJO* /forum/post/16960287
> 
> 
> Is there any low-cost (or free) software that does the ray tracing method? Is an AutoCAD 3D model sufficient?
> 
> 
> Thanks,
> 
> CJ



Here are two aids:
http://www.avsforum.com/avs-vb/showthread.php?t=822273 
http://www.avsforum.com/avs-vb/showt...20#post9615620


----------



## erkq




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16959479
> 
> 
> Of course, many people just make a guess at room treatment.



I took a guess to hold me over while I read up on the subject. What I did with the screen wall (I have an AT screen) and reflection points is effective but I now find sloppy mic'ing really annoying, and there's a lot of it. I find that even in the same scene a character's dialog comes from different recording sessions that have different mic distances (very common), different reverberation, and even (less common) different frequency content. The sudden change is so obvious it take me out of the story. Even my g'friend notices.


----------



## Ethan Winer




> Quote:
> Originally Posted by *mhdiab* /forum/post/16958430
> 
> 
> This thread spans 6 years and 170 pages which is cool. However, it is becoming harder and harder to find a good summary of things that are must do's and things that are good to do. Does anyone have a link to something good like that?



Yes, this is much better:

Acoustics FAQ 



> Quote:
> What I got from the first post here is to cover the
> 
> FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling



I disagree, as explained in detail here:

Front Wall Absorption 



> Quote:
> So considering that I have an existing room with carpet is there something else that "isn't to late" but that I really should do before I do anything else?



You need bass traps.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *CJO* /forum/post/16960287
> 
> 
> Is there any low-cost (or free) software that does the ray tracing method? Is an AutoCAD 3D model sufficient?
> 
> 
> Thanks,
> 
> CJ



Unfortunately, ray tracing software is very expensive. It's designed for high-end architectural acoustics. All such packages (I think) will import AutoCAD DXF files when created and formatted appropriately. Each specific CAD layer maps to an acoustic material with defined absorption and diffusion.


EASE 4.2 ($2200) plus AURA ($1000) is one of the _lower_ priced packages whose performance is as good as any in the world. You need AURA for full ray tracing functionality. And there's still a relatively steep learning curve.


But you can get pretty close with just the Eyring equation, and Chris Whealy's free spreadsheet for this. If the room geometry and distribution of absorption is relatively uniform, and you don't need to model diffusion, the two methods yield the same numbers.


- Terry


----------



## Terry Montlick




> Quote:
> Originally Posted by *mhdiab* /forum/post/16960135
> 
> 
> Terry
> 
> 
> Thanks for the post that is a really neat calculator. I am guessing Wall 1 is the front wall -- correct?



Actually, it doesn't matter. The formulas (Eyring, Sabine, Fitzroy, etc.) compute overall reverberation times for the room. These don't vary much with room position. Though again, ray tracing will provide differences where there are any.


> Quote:
> Came up with
> 
> 
> User defined absorbant wall surface
> 
> Plasterboard on frame
> 
> 50% each
> 
> 
> Not even sure what to do with that information - lol



I recommend the beginner's acoustics book that everyone else does: Everest's Master Handbook of Acoustics .


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16961090
> 
> 
> I recommend the beginner's acoustics book that everyone else does: Everest's Master Handbook of Acoustics .



Great book to start with...accessible but fairly thorough.


Frank


----------



## dogone

Has anyone used GOM Thin Loop Fabric (hook and loop) for their theater?...Just curious. It seems as it would make a great acoustic material covering.


----------



## zmisst




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/16886782
> 
> 
> In actual practice, you may absolutely want absorptive materials to stay out of early reflection points.



This comment seems to have gone unnoticed and that the "put absorption at first reflection points" conventional wisdom seems to still be alive and well, despite Dennis's occasional comments like above and also Floyd Toole's recent book which published his research and blind listening test and studies where he wrote:


"We are left, though, with a problem: how to explain why the often mentioned comb filtering engendered by early reflections is not a problem. None of the listeners heard it, or at least didn't comment on it except to say that they prefer sounds with reflections. . . . *If there is a subjective response to comb filtering, it is that it appears to have a beneficial effect*. (p. 140)


As far as imaging and reflections, his whole chapter 8 is about it and the conclusion is *that first reflections help imaging*. Specifically he wrote that


"When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas *reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.'*" (p. 116).

*Why is absorption at first reflections still such a dogma of acoustic design in this thread*, despite real evidence and informed guidance to the contrary?


----------



## whumpf




> Quote:
> Originally Posted by *zmisst* /forum/post/16970042
> 
> 
> As far as imaging and reflections, his whole chapter 8 is about it and the conclusion is *that first reflections help imaging*. Specifically he wrote that
> 
> 
> "When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas *reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.'*" (p. 116).
> 
> *Why is absorption at first reflections still such a dogma of acoustic design in this thread*, despite real evidence and informed guidance to the contrary?



I have read somewhere, maybe Toole's book or somewhere on this forum, that the typical absorber put at first reflection points is at such a shallow angle of incidence to the sound waves that they act more as reflectors than absorbers.


Question: THe passage you have quoted above is about stereo music. Does it hold for multichannel?


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/16970042
> 
> 
> This comment seems to have gone unnoticed and that the "put absorption at first reflection points" conventional wisdom seems to still be alive and well, despite Dennis's occasional comments like above and also Floyd Toole's recent book which published his research and blind listening test and studies where he wrote:
> 
> 
> "We are left, though, with a problem: how to explain why the often mentioned comb filtering engendered by early reflections is not a problem. None of the listeners heard it, or at least didn't comment on it except to say that they prefer sounds with reflections. . . . *If there is a subjective response to comb filtering, it is that it appears to have a beneficial effect*. (p. 140)
> 
> 
> As far as imaging and reflections, his whole chapter 8 is about it and the conclusion is *that first reflections help imaging*. Specifically he wrote that
> 
> 
> "When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas *reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.'*" (p. 116).
> 
> *Why is absorption at first reflections still such a dogma of acoustic design in this thread*, despite real evidence and informed guidance to the contrary?



For home theater/cinema, why would we want the sound image broader than it was in the mixdown studio? And, especially for those of us with LCR behind an AT screen, why would we want the image wider than the image? And if that is desirable, companies such as Audyssey are working on mathmatically deriving discrete "wide" and "height" channels from the information already in the soundtracks. It makes more sense to me to place speakers for these channels to enlarge the image in a consistent manner than to rely upon varying room acoustics.


Just my $.02.


- Jeff


----------



## CJO




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/16960558
> 
> 
> Here are two aids:
> http://www.avsforum.com/avs-vb/showthread.php?t=822273
> http://www.avsforum.com/avs-vb/showt...20#post9615620



Thanks, Kal. I'm familiar with those. I think that what Terry was talking about was a program that simulates playing a range of sounds and will model how they interact with each other and the room boundaries.



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16961017
> 
> 
> Unfortunately, ray tracing software is very expensive. It's designed for high-end architectural acoustics. All such packages (I think) will import AutoCAD DXF files when created and formatted appropriately. Each specific CAD layer maps to an acoustic material with defined absorption and diffusion.
> 
> 
> EASE 4.2 ($2200) plus AURA ($1000) is one of the _lower_ priced packages whose performance is as good as any in the world. You need AURA for full ray tracing functionality. And there's still a relatively steep learning curve.
> 
> 
> But you can get pretty close with just the Eyring equation, and Chris Whealy's free spreadsheet for this. If the room geometry and distribution of absorption is relatively uniform, and you don't need to model diffusion, the two methods yield the same numbers.
> 
> 
> - Terry



Thanks, Terry. It looks like I'll stick with the spreadsheet for now!


CJ


----------



## Terry Montlick




> Quote:
> Originally Posted by *zmisst* /forum/post/16970042
> 
> *Why is absorption at first reflections still such a dogma of acoustic design in this thread*, despite real evidence and informed guidance to the contrary?



The culprit would be _Floyd Toole_.







His classic 1988 paper with Sean Olive, The Detection of Reflections in Typical Rooms , was the first to quantify image-shifting caused by early reflections. It led to the early reflection limits adopted in 1998 EBU Technical Recommendation 3276, "Listening conditions for the assessment of sound programme material: monophonic and two–channel stereophonic," and its 1999 Supplement, "Listening Conditions for the assessment of sound programme material: multichannel sound."


----------



## rhcorolla

After doing a fair amount of research & analysis, I decided to go w/ DIY acoustical panels for my difficult “live” 16’ w x 11’ d x 8’ h room w/ 4 openings.


My 5.1 HT/ audio system: av123 525 towers & center, Paradigm surrounds, Rythmik F12G subwoofer, Denon avr-1909 w/ Audyssey, Oppo BDP-83 blu-ray, Pio 4280HD plasma.


Total material costs for OC-703 2” thk 4' x 8'- 64 ft2 frk backing panels panels thru local insulation contractor, 11 yds. burlap fabric covering on sale at Hobby Lobby, 2 cans spray adhesive, & fastener hardware was $133.


My total time to make/ mount (5) 2” early reflection panels (3 panels were 24” x 36” to mount above 2’ h bookshelves/ cabinets), & (2) 4” bass traps incl. material purchases was about 20 hrs. or so.


I thought the panels turned out pretty darn good, but believe me, I have a much finer appreciation for RealTraps & GIK Acoustic panel costs (DIY fabrication is somewhat difficult, messy & back-breaking). Wood or metal frames definitely would give a better fit/ finish vs. folded burlap ends (I wrapped like a Xmas present & glued flat). I can of course add wood frames later, but wanted to try & keep the panels lighter for simpler hanging purposes while maintaining 1.5” gap from walls for 2” panels.


Performance-wise, I was truly floored. My problematic room was tamed dramatically w/ acoustical panels installed & a couple small rugs strategically placed. MUCH finer detail, nuance, delicate vocals were immediately evident. Bass was less boomy, much tighter. Of course it is a different sound than I am accustomed to since previously I had sound waves bouncing all over the place, but once the ears/ brain adjust, it’s a dramatic improvement. Only problem I have is that I want to crank up the volume, & Rat Shack SPL meter keeps telling me I’m listening about 6 to 8 dB louder than before.









*Many thanks* to those on this thread, GIK Acoustics articles, RealTrap articles & particularly *Ethan Winer*, whose “Rigid Fiberglss Density Tests” article was instrumental (pun intended) in the methods I employed for my particular situation.

Edit: Attached are pics of my modest attempt @ DIY acoustical panels (which look far better than pics show). I’m well aware that I have a severely compromised room layout. Factoring in WAF & all, I did the best I could w/ what I had to work with... ie. before: 0 panels, after: 5 early reflection panels (2 panels directly behind rear wall bookshelves) & 2 bass traps.


PS, sub is behind blue recliner @ back wall corner. Front wall no panels.... yet.


----------



## allredp




> Quote:
> Originally Posted by *rhcorolla* /forum/post/16973710
> 
> 
> After doing a fair amount of research & analysis, I decided to go w/ DIY acoustical panels for my difficult live 16' w x 11' d x 8' h room w/ 4 openings.
> 
> 
> My 5.1 HT/ audio system: av123 525 towers & center, Paradigm surrounds, Rythmik F12G subwoofer, Denon avr-1909 w/ Audyssey, Oppo BDP-83 blu-ray, Pio 4280HD plasma.
> 
> 
> Total material costs for OC-703 2 thk 4' x 8'- 64 ft2 frk backing panels panels thru local insulation contractor, 11 yds. burlap fabric covering on sale at Hobby Lobby, 2 cans spray adhesive, & fastener hardware was $133.
> 
> 
> My total time to make/ mount (5) 2 early reflection panels (3 panels were 24 x 36 to mount above 2' h bookshelves/ cabinets), & (2) 4 bass traps incl. material purchases was about 20 hrs. or so.
> 
> 
> I thought the panels turned out pretty darn good, but believe me, I have a much finer appreciation for RealTraps & GIK Acoustic panel costs (DIY fabrication is somewhat difficult, messy & back-breaking). Wood or metal frames definitely would give a better fit/ finish vs. folded burlap ends (I wrapped like a Xmas present & glued flat). I can of course add wood frames later, but wanted to try & keep the panels lighter for simpler hanging purposes while maintaining 1.5 gap from walls for 2 panels.
> 
> 
> Performance-wise, I was truly floored. My problematic room was tamed dramatically w/ acoustical panels installed & a couple small rugs strategically placed. MUCH finer detail, nuance, delicate vocals were immediately evident. Bass was less boomy, much tighter. Of course it is a different sound than I am accustomed to since previously I had sound waves bouncing all over the place, but once the ears/ brain adjust, it's a dramatic improvement. Only problem I have is that I want to crank up the volume, & Rat Shack SPL meter keeps telling me I'm listening about 6 to 8 dB louder than before.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Many thanks* to those on this thread, GIK Acoustics articles, RealTrap articles & particularly *Ethan Winer*, whose Rigid Fiberglss Density Tests article was instrumental (pun intended) in the methods I employed for my particular situation.



Pics!!!


----------



## rhcorolla




> Quote:
> Originally Posted by *allredp* /forum/post/16974830
> 
> 
> Pics!!!



I knew that was coming the second I hit the "reply" button.







I'll try to take a couple pics tonight & edit my post.


----------



## Weasel9992




> Quote:
> Originally Posted by *allredp* /forum/post/16974830
> 
> 
> Pics!!!



+1 for DIY acoustic panel porn. DIYAPP for us industry folks.


Frank


----------



## allredp




> Quote:
> Originally Posted by *rhcorolla* /forum/post/16974894
> 
> 
> I knew that was coming the second I hit the "reply" button.
> 
> 
> 
> 
> 
> 
> 
> I'll try to take a couple pics tonight & edit my post.



Looking forward to them, rhcorolla!


I'm at that stage of things myself and have 10 panels of JM spinglass 3" thick, so I'm looking opinions about what I should do with them that will give me the most bang (or should I say least boomy-ness) with my 10 panels!











BTW, the sub position is under advisement as I'm figuring out how to best use my new toy: Mark Seaton's amazing *SubMersive-1*!







So far, without EQ or Audyssey, this thing is really something--especially for music.


As I figure it I have two main options with a third possibility as well considering I only have 10 panels.


Option 1: triangle cut the panels into the classic super-chunk corner trap (17" x 17" x 24"). At 3" thick I can stack them on top of each other to form one room corner floor to ceiling.


Option 2: I can double the panels up to make two 6" thick panels to straddle 2 corners floor-ceiling.


(both options use 8 of my 10 panels, leaving me with options for first reflections or back wall treatment with the remaining 2 panels).


Or the other possibility is to triangle cut chunks of the same size and fill my floor/back wall intersection for 12' directly behind my seating position.


So, it is either 1 corner filled with a super-chunk, or 2 corners covered with panels, or the back wall/floor filled with 12' of super-chunk.


Help much appreciated!


ADDITION:


I have 3" mineralwool panels completely covering behind my AT screen with beveled cut-out for my center speaker. FWIW, I've kept about 1" of space between the mineral wool and the wall creating basically 4" of absorption.


----------



## Ethan Winer




> Quote:
> Originally Posted by *zmisst* /forum/post/16970042
> 
> *Why is absorption at first reflections still such a dogma of acoustic design in this thread*, despite real evidence and informed guidance to the contrary?



Very simple: There's no accounting for taste.










To me, the improvement from having absorption at reflection points is so incredibly obvious that I can't imagine anyone who has heard it both ways disagreeing. Yet some disagree anyway. They are definitely in the minority of people who have heard both. Maybe in a really large room where the reflection points are ten feet away or farther, absorption may not matter as much. In that case the reflections might be "first" reflections, but they won't be "early."


Have you heard it both ways? If not, try it yourself and see what you think. Even a couple of folded over bath towels will absorb enough to make an informed decision. Another way to hear the difference is to watch my recent video Hearing is Believing . The first audible comparison is a smallish room that's fully treated versus no treatment. Ignore the difference in bass clarity and just focus on the mids and highs.


--Ethan


----------



## glaufman

Because for some of us, once you start listening critically, you never truly stop... once you learn to pick out flaws, you hear them everywhere you go...


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/16976019
> 
> 
> Because for some of us, once you start listening critically, you never truly stop... once you learn to pick out flaws, you hear them everywhere you go...



One must know when - and how - to exit evaluation mode and just relax and enjoy.


----------



## glaufman




> Quote:
> Originally Posted by *pepar* /forum/post/16976304
> 
> 
> One must know when - and how - to exit evaluation mode and just relax and enjoy.



A worthy goal to be sure, but more difficult for some than for others.


----------



## CJO




> Quote:
> Originally Posted by *zmisst* /forum/post/16970042
> 
> 
> Quote:
> 
> Originally Posted by *Dennis Erskine*
> _In actual practice, you may absolutely want absorptive materials to stay out of early reflection points._
> 
> This comment seems to have gone unnoticed and that the "put absorption at first reflection points" conventional wisdom seems to still be alive and well, despite Dennis's occasional comments like above...



I think his comment is somewhat ambiguous. He is not saying that you never want absorption, or that you never want some sort of treatment at reflective points. He is saying that there are some cases where you don't and that it depends on the room. In my case, due to the dispersion patterns of my particular speakers, he recommended diffusion at the first reflection points.


CJ


----------



## allredp




> Quote:
> Originally Posted by *allredp* /forum/post/16975288
> 
> 
> Looking forward to them, rhcorolla!
> 
> 
> I'm at that stage of things myself and have 10 panels of JM spinglass 3" thick, so I'm looking opinions about what I should do with them that will give me the most bang (or should I say least boomy-ness) with my 10 panels!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> BTW, the sub position is under advisement as I'm figuring out how to best use my new toy: Mark Seaton's amazing *SubMersive-1*!
> 
> 
> 
> 
> 
> 
> 
> So far, without EQ or Audyssey, this thing is really something--especially for music.
> 
> 
> As I figure it I have two main options with a third possibility as well considering I only have 10 panels.
> 
> 
> Option 1: triangle cut the panels into the classic super-chunk corner trap (17" x 17" x 24"). At 3" thick I can stack them on top of each other to form one room corner floor to ceiling.
> 
> 
> Option 2: I can double the panels up to make two 6" thick panels to straddle 2 corners floor-ceiling.
> 
> 
> (both options use 8 of my 10 panels, leaving me with options for first reflections or back wall treatment with the remaining 2 panels).
> 
> 
> Or the other possibility is to triangle cut chunks of the same size and fill my floor/back wall intersection for 12' directly behind my seating position.
> 
> 
> So, it is either 1 corner filled with a super-chunk, or 2 corners covered with panels, or the back wall/floor filled with 12' of super-chunk.
> 
> 
> Help much appreciated!
> 
> 
> ADDITION:
> 
> 
> I have 3" mineralwool panels completely covering behind my AT screen with beveled cut-out for my center speaker. FWIW, I've kept about 1" of space between the mineral wool and the wall creating basically 4" of absorption.



Any thoughts on which option would maximize my 10--3" x 2' x 4' panels the best for bass-trapping?


Much obliged!


----------



## rhcorolla




> Quote:
> Originally Posted by *allredp* /forum/post/16981880
> 
> 
> Any thoughts on which option would maximize my 10--3" x 2' x 4' panels the best for bass-trapping?
> 
> 
> Much obliged!



allrepdp, Have you read Ethan Winer's excellent article "Rigid Fiberglass Density Tests"?

http://www.ethanwiner.com/density/density.html 


Testing OC-703 w/ frk-backing pretty much indicates more panels is better versus half as many/ twice as thick.


Everything I have read though says 4" minimum for bass traps, & the thicker the better.


Hard to know where to draw the line, isn't it? So many variables/ caveats/etc.. I figure it's all good, esp. compared to untreated walls.


----------



## aboroth00

I was wondering how you guys hung your panels, whether it be fish wire, steel wire, d-hooks.


----------



## pepar




> Quote:
> Originally Posted by *aboroth00* /forum/post/16983539
> 
> 
> I was wondering how you guys hung your panels, whether it be fish wire, steel wire, d-hooks.



Small angle brackets for me.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *aboroth00* /forum/post/16983539
> 
> 
> I was wondering how you guys hung your panels, whether it be fish wire, steel wire, d-hooks.



Rotofast mounts of different types: http://www.rotofast.com/


----------



## allredp




> Quote:
> Originally Posted by *rhcorolla* /forum/post/16982282
> 
> 
> allrepdp, Have you read Ethan Winer's excellent article "Rigid Fiberglass Density Tests"?
> 
> http://www.ethanwiner.com/density/density.html
> 
> 
> Testing OC-703 w/ frk-backing pretty much indicates more panels is better versus half as many/ twice as thick.
> 
> 
> Everything I have read though says 4" minimum for bass traps, & the thicker the better.
> 
> 
> Hard to know where to draw the line, isn't it? So many variables/ caveats/etc.. I figure it's all good, esp. compared to untreated walls.



Thanks for the link--more reading, eh?! And here I thought I was on summer break!


----------



## Ethan Winer




> Quote:
> Originally Posted by *allredp* /forum/post/16983827
> 
> 
> Thanks for the link--more reading, eh?!



That's the hidden cost of DIY.










--Ethan


----------



## mhdiab




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/16983615
> 
> 
> Rotofast mounts of different types: http://www.rotofast.com/



How do you get an air gap with those mounts?


----------



## pepar

I don't think you can.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *mhdiab* /forum/post/16990306
> 
> 
> How do you get an air gap with those mounts?



I bought some plastic pucks from Home Depot for the 1" spacing. For greater spacing, I made up spacers by drilling out appropriate lengths of 1.5" dowel (closet clothes bar stock) and using longer screws but decided not to use them.


----------



## zmisst




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16971701
> 
> 
> The culprit would be _Floyd Toole_.
> 
> 
> 
> 
> 
> 
> 
> His classic 1988 paper with Sean Olive, The Detection of Reflections in Typical Rooms , was the first to quantify image-shifting caused by early reflections. It led to the early reflection limits adopted in 1998 EBU Technical Recommendation 3276, "Listening conditions for the assessment of sound programme material: monophonic and two-channel stereophonic," and its 1999 Supplement, "Listening Conditions for the assessment of sound programme material: multichannel sound."



From the abstract to that paper, it doesn't seem like he was suggesting absorption at first reflections points:



"Reflected sounds influence the timbre and spatial character of live and reproduced sounds. Most investigations of reflections have focused on the performance of live sounds in large halls. Current interest in the acoustical interactions of rooms, loudspeakers, and listeners, requires further and possibly more relevant data than has been available. In this study, the effects of reflected sounds were examined as they would occur in stereophonic reproduction in rooms of domestic or control-room size. Thresholds were determined as a function of level relative to the direct sound, the angle of incidence, spectrum, the temporal form of the signal and reverberation. The relationships between audible effects and measurements, such as ETC and frequency response, are discussed."


When he later reports on blind tests of listener preference in his recent book, he finds that blind test listeners prefer the first order reflections to absorption at that point. I don't believe Toole tested diffusion at first reflection points which seems to be what some acoustic designers often recommend.


Re multichannel: Floyd discusses multichannel quite a bit -- his whole final chapters where he gives specific recommendations are based on multichannel rooms and he still maintains lateral/early reflections are never harmful b/c they are swamped by any actual surround content, and to the extent that there isn't any surround content (i.e., during portions that are essentially stereo) the lateral reflections are beneficial.


Here are few relevant quotes:


"The locations of the first side-wall reflections at the front of the room are specified as areas for optional treatment. Leaving these areas as flat wall surfaces provides an open and spacious soundstage for those customers who listen in stereo. In television and movies these reflections will "soften" the image of the commonly dominant center channel. *Well-designed wide-dispersion front loudspeakers will generally sound better in the presence of lateral reflections. When multiple channels are operating simultaneously, these reflections are swamped by the recorded sounds and become neutral factors. So, the effects of these side-wall reflections range from neutral to slightly beneficial. In any event, they are not large effects, so the choice can be left to the designer.*"


"In professional environments, like recording control rooms, it has been common practice to absorb these side-wall reflections from the front loudspeakers. As discussed in Chapter 8, most recreational listeners have voted that they enjoy them in stereo reproduction. In a multichannel context, the matter is open for discussion. If the surround channels are active, it is probable that the modest spatial contributions of these front-channel reflections will be masked. If only the front channels, especially the center channel, are active, it is possible that a small spatial effect may be beneficial. "


and also,


"The most common problem in custom home theaters is that they are too 'dead.' In conversation, voices sound muffled, and more than the usual amount of vocal effort is required. It is not a relaxing situation. However, I know of designers who have done this deliberately to make the theater seem 'special.'"


Toole also mentions Lexicon and THX surround processing and suggests that those *surround processing modes sound better in part because they add their own "artificial" reflections to the sound from the front speakers -- in a sense duplicating and even amplifying those first reflections that some go to great lengths to abolish with absorption at first reflections*.


Toole did blind tests that showed people preferred first reflections to absorption.


Has anyone done similar blind tests that show that people prefer absorption at first reflections?


and note, you should test just the difference in absorption at first reflection or not -- you shouldn't test the difference between some absorption and no absorption; i.e., to test, don't just put absorption up at first reflection and then take it out of the room. Test the room with equivalent overall absorption the room, but in one case with absorption at first reflection and the other case with the same absorption somewhere else in the room so you are testing just the variable of first order absorption with equivalent overall absorption/reverb in the room (and not just testing two different overall absorption/reverb levels).


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/16999470
> 
> 
> . . .As discussed in Chapter 8, most recreational listeners have voted that they enjoy them in stereo reproduction. *In a multichannel context, the matter is open for discussion.* If the surround channels are active, it is probable that the modest spatial contributions of these front-channel reflections will be masked. If only the front channels, especially the center channel, are active, it is possible that a small spatial effect may be beneficial. "



Many/Most of us here have home theaters with 5.1/7.1 systems with a predominance of usage being cinema. It seems that when this first reflection point absorption issue is being argued discussed, 5.1/7.1 cinema use is ignored, or it is conflated with 2-channel music reproduction. I do not need blind tests to tell me that my theater's performance improved dramatically with the addition of absorbers at the first reflection points.


----------



## Terry Montlick




> Quote:
> Originally Posted by *zmisst* /forum/post/16999470
> 
> 
> From the abstract to that paper, it doesn't seem like he was suggesting absorption at first reflections points:



You have to read the entire paper, not just the abstract. Treatment is not discussed. This is psychoacoustics research.


From the paper:



> Quote:
> In a few experiments, a second kind of threshold was determined. Called the image-shift threshold, this was the reflection level at which there was a just-discernable shift in the location or size of the principal auditory image.


----------



## glaufman




> Quote:
> Originally Posted by *zmisst* /forum/post/16999470
> 
> 
> to test, don't just put absorption up at first reflection and then take it out of the room. Test the room with equivalent overall absorption the room, but in one case with absorption at first reflection and the other case with the same absorption somewhere else in the room so you are testing just the variable of first order absorption with equivalent overall absorption/reverb in the room (and not just testing two different overall absorption/reverb levels).



Issue with doing this is anywhere you put the absorption, it becomes a second variable in the test... to null that out you have to run multiple tests with putting that absorption in a myriad of different places...


I'm more inclined to say, if you're hearing something that's bothering you, that you can trace to FRP, treat it. But if not, it's POSSIBLE an "If it ain't broke don't fix it" attitude is preferable... but I'd sure like to hear more debate...


Of course then we get down to, when he says listener "prefer" it, what kind of profile do these listeners fall into... obviuosly they can discern the difference, but... similar to those people who don't care how accurate the bass is as long as it's LOUD, are these people who want it to sound spacious, even if that spaciousness is incoherent? I know I know, read the whole paper, not just the abstract...


----------



## zmisst




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/16999885
> 
> 
> You have to read the entire paper, not just the abstract. Treatment is not discussed. This is psychoacoustics research.
> 
> 
> From the paper: Quote:
> 
> 
> In a few experiments, a second kind of threshold was determined. Called the image-shift threshold, this was the reflection level at which there was a just-discernable shift in the location or size of the principal auditory image.




I don't know the context of this quote, it seems to simply say that first reflection absorption (or not) just barely shifts the image.


If anything, since the shift is "just-discernable" that suggests that the effect (whether good or bad) is very minor.


In any case, despite whatever this old paper may or may not conclude, in Toole's very recent and authoritative book the message is pretty clear: based on the evidence from blind tests (and those that read the book would know that the test panel was not random listeners), and the opinion of a very well-informed expert, and explained in very reasonable and persuasive terms, first order lateral reflection absorption is of no value in multi-channel setups and is harmful in stereo setups.


He does mention exceptions to this for 1) speakers with poor off-axis response and 2) professional mixing environments where engineers who are working, rather than trying to enjoy the sound, want to listen to the speaker source directly.


Also he does make clear that diffusion, sub location and number, general absorption and especially bass trapping in a room are all very important. But if you read the book you can't help but come to the conclusion that all the fuss with mirrors and protractors and cool-looking reflection-plotting applets does more harm than good.


----------



## pepar




> Quote:
> Originally Posted by *zmisst* /forum/post/17002225
> 
> 
> . . the message is pretty clear: based on the evidence from blind tests and the opinion of a very well-informed expert, and explained in very reasonable and persuasive terms, the opinion of a very well-informed expert, first order lateral reflection absorption is of *no value in multi-channel setups* . .





> Quote:
> if you read the book you can't help but come to the conclusion that all the fuss with mirrors and protractors and cool-looking reflection-plotting applets *does more harm than good*.



In spite of how clear the message is, some seem to conclude what they want to conclude.

















And that is exactly how this issue always plays out whenever it comes up.


----------



## cinema mad

If room Acoustics intrests you I highly recommend Floyd E Toole's latest book Sound Reproduction loudspeakers and rooms..


It is more biased towards surround sound & Home theater setups speaker layout and how to deal with room acoustics & related issues, it give's A different perspective to other related books I have read..


IMO The problem with room Acoustics, as with other complexed specialized fields there is A lot of biased snake oil and misinfomation out there, you cant believe every thing you read or hear rather listen to all sides keeping an open mined and research as much as you can or just hire A pro with A proven back ground like Terry Montlick







....


Cheers...


----------



## Tonmeister2008




> Quote:
> Originally Posted by *zmisst* /forum/post/16999470
> 
> 
> From the abstract to that paper, it doesn't seem like he was suggesting absorption at first reflections points:
> 
> 
> Toole did blind tests that showed people preferred first reflections to absorption.
> 
> 
> Has anyone done similar blind tests that show that people prefer absorption at first reflections?
> 
> 
> and note, you should test just the difference in absorption at first reflection or not -- you shouldn't test the difference between some absorption and no absorption; i.e., to test, don't just put absorption up at first reflection and then take it out of the room. Test the room with equivalent overall absorption the room, but in one case with absorption at first reflection and the other case with the same absorption somewhere else in the room so you are testing just the variable of first order absorption with equivalent overall absorption/reverb in the room (and not just testing two different overall absorption/reverb levels).



I don't think anyone has done a specific experiment where they added and removed the first lateral reflection produced from a loudspeaker in a room and asked listeners which one they preferred. The paper that Floyd and I wrote on reflections was focussed on measuring the absolute detection thresholds of the first lateral reflection, and their various effects (image shift, spaciousness, echo) -- not preference. Most of the evidence that people prefer the first lateral reflection is based on concert hall data, and stereo/mono loudspeaker tests that show that wider dispersion loudspeakers are preferred over narrower ones -- all other things being equal (good on and off-axis response, smooth DI ).


The closest experiment I know is one I at NRC in the anechoic chamber (1985) where I simulated the ceiling and wall reflections produced from a stereo playback system in typical listening room. People rated the fidelity/preference of different music programs reproduced in stereo, with and without the first reflections added. On average, people preferred the music reproduction with the lateral reflections included. I did not include the other room reflections in the simulation so the ecological validity of the results is somewhat lacking.


The best sound field simulation of a loudspeaker in a listening room I know was the Archimedes project done in Denmark around 1990. They simulated many of the early reflections in an IEC listening room using multiple loudspeakers surrounding the listener. Unfortunately, the results did not include a measure of what listeners preferred, rather it focused on which individual reflections were audible. Rather sad that more wasn't learned given the potential opportunities afforded with such a setup. http://www.aes.org/e-lib/browse.cfm?elib=7673


----------



## Roger Dressler




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17006198
> 
> 
> I don't think anyone has done a specific experiment where they added and removed the first lateral reflection produced from a loudspeaker in a room and asked listeners which one they preferred.
> 
> 
> [snip]
> 
> 
> Unfortunately, the results did not include a measure of what listeners preferred, rather it focused on which individual reflections were audible. Rather sad that more wasn't learned given the potential opportunities afforded with such a setup. http://www.aes.org/e-lib/browse.cfm?elib=7673



What a drag. Now we have to leave the question of preference up to the individual...


----------



## pepar




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17006198
> 
> 
> I don't think anyone has done a specific experiment where they added and removed the first lateral reflection produced from a loudspeaker in a room and asked listeners which one they preferred. The paper that Floyd and I wrote on reflections was focussed on measuring the absolute detection thresholds of the first lateral reflection, and their various effects (image shift, spaciousness, echo) -- not preference. Most of the evidence that people prefer the first lateral reflection is based on concert hall data, and stereo/mono loudspeaker tests that show that wider dispersion loudspeakers are preferred over narrower ones -- all other things being equal (good on and off-axis response, smooth DI ).
> 
> 
> The closest experiment I know is one I did an experiment at NRC in the anechoic chamber (1985) where I simulated the ceiling and wall reflections produced from a stereo playback system in typical listening room. People rated the fidelity/preference of different music programs reproduced in stereo, with and without the first reflections added. On average, people preferred the music reproduction with the lateral reflections included. I did not include the other room reflections in the simulation so the ecological validity of the results is somewhat lacking.
> 
> 
> The best sound field simulation of a loudspeaker in a listening room I know was the Archimedes project done in Denmark around 1990. They simulated many of the early reflections in an IEC listening room using multiple loudspeakers surrounding the listener. Unfortunately, the results did not include a measure of what listeners preferred, rather it focused on which individual reflections were audible. Rather sad that more wasn't learned given the potential opportunities afforded with such a setup. http://www.aes.org/e-lib/browse.cfm?elib=7673



Thank you for your post. THANK YOU!


----------



## Terry Montlick

Yes, thank you so much for joining the conversation, Sean!


I was incorrect when I stated that your early reflection research led to the EBU reflection recommendations. Floyd set me straight -- that he didn't think that this research had anything to do with the recommendations. This makes a lot of sense, since the EBU considers only the first 15 ms, while your research covered the first 80 ms.


Regards,

Terry


----------



## Tonmeister2008




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17006437
> 
> 
> Yes, thank you so much for joining the conversation, Sean!
> 
> 
> I was incorrect when I stated that your early reflection research led to the EBU reflection recommendations. Floyd set me straight -- that he didn't think that this research had anything to do with the recommendations. This makes a lot of sense, since the EBU considers only the first 15 ms, while your research covered the first 80 ms.
> 
> 
> Regards,
> 
> Terry



Hi Terry,

Thanks. Yes, I think you're correct. The EBU recommendation also said you only need to attenuate the early reflections > 1 kHz, which doesn't make the reflection much less audible but does make it colored. The people who wrote the standard have admitted they did the best job given what knowledge they had at the time , which was apparently very little


----------



## TumaraBaap




> Quote:
> Originally Posted by *zmisst* /forum/post/17002225
> 
> 
> He does mention exceptions to this for 1) speakers with poor off-axis response and 2) professional mixing environments where engineers who are working, rather than trying to enjoy the sound, want to listen to the speaker source directly.



Toole at the most extends engineers the benefit of doubt that they may be overly sensitized to reflections compared to the non-pro. He doesn't endorse their habits. On the contrary he leans the other way.


Regarding poor off axis speakers, Toole writes:


"....wide dispersion loudspeakers with what would appear to be compromised sound quality are given a higher sound quality and spatial quality ratings than a narrow dispersion loudspeaker with potentially superior sound quality... listeners appeared to prefer the sound from wide dispersion loudspeakers with somewhat colored off-axis behavior to the sound from a narrow dispersion loudspeaker with less colored off-axis behavior. In the years since then, it has been shown that improving the smoothness of the off-axis radiated sound pushes the subjective ratings even further up, so it is something not to be neglected."


This doesn't contradict zmisst since Toole does not address uniformly terrible off-axis performance in this section. But I hope it sheds light on the topic.


So just think about it. What do you do when using just a couple inch thick absorbers at first reflection points? You attenuate the amplitude of reflections making the loudspeaker essentially behave as a narrow dispersion design.Ouch. Furthermore, you worsen the tonal coloration of the loudspeaker. Ouch. That's what's called a double whammy.


Tumara Baap


----------



## pepar

If "most of the evidence that people prefer the first lateral reflection is based on concert hall data, and stereo/mono loudspeaker tests that show that wider dispersion loudspeakers are preferred over narrower ones", can it be safely inferred that the preference would hold for multichannel systems reproducing cinema soundtracks as well? Until there is the experiment that Tonmeister2008 said has never been done "where they added and removed the first lateral reflection produced from a loudspeaker in a room and asked listeners which one they preferred" people will extrapolate for multichannel systems and draw their conclusions based on the way they were leaning in the first place.


Why hasn't this testing ever been done? Why hasn't this subject been updated for modern home theaters?


----------



## Tonmeister2008




> Quote:
> Originally Posted by *pepar* /forum/post/17008165
> 
> 
> If "most of the evidence that people prefer the first lateral reflection is based on concert hall data, and stereo/mono loudspeaker tests that show that wider dispersion loudspeakers are preferred over narrower ones", can it be safely inferred that the preference would hold for multichannel systems reproducing cinema soundtracks as well? Until there is the experiment that Tonmeister2008 said has never been done "where they added and removed the first lateral reflection produced from a loudspeaker in a room and asked listeners which one they preferred" people will extrapolate for multichannel systems and draw their conclusions based on the way they were leaning in the first place.
> 
> 
> Why hasn't this testing ever been done? Why hasn't this subject been updated for modern home theaters?



Good question: why haven't more people done psychoacoustic experiments to learn what the optimal acoustical treatment of the room should be for multichannel music and film/TV broadcast? One reason is that doing a listening experiment that manipulates the acoustical treatment in a controlled manner is challenging. I think binaural room scanning (BRS) is a solution for that problem. BRS allows you in sequence to binaurally scan the room acoustically treated in various ways, and later play them back over head-tracking headphones permitting double blind multiple comparisons among the different room treatments in very controlled way.


We have such a device - and we have a multichannel setup in a room that we can easily vary its acoustical treatment.


It's on my list of research projects. I'm just looking for a PhD student or an acoustical treatment company that might be willing to sponsor it...


----------



## pepar




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17008555
> 
> 
> It's on my list of research projects. I'm just looking for a PhD student or an acoustical treatment company that might be willing to sponsor it...



The cynic in me questions whether or not acoustical treatment companies may not have a vested interest in leaving it up in the air if FRP absorption is a good thing.


----------



## Tonmeister2008




> Quote:
> Originally Posted by *pepar* /forum/post/17008608
> 
> 
> The cynic in me questions whether or not acoustical treatment companies may not have a vested interest in leaving it up in the air if FRP absorption is a good thing.



Yes, that thought too has crossed my mind. It may explain why I've had no luck finding a sponsor so far...










We have broadband diffusers and absorbers in our room, and just purchased some RPG Modex Plate absorbers for a problematic room that had walls that were too stiff (2 layers of drywall)- so I don't think the acoustical treatment companies that build legitimate products need to worry.


It's just a question of how what type and much acoustical treatment you need, how broadband should it be, and where is the best place to put it -- based on results of psychoacoustic experiments. Those are scientific questions that need to be answered.


----------



## Lonely Raven




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17009461
> 
> 
> 
> We have broadband diffusers and absorbers in our room, and just purchased some RPG Modex Plate absorbers for a problematic room that had walls that were too stiff (2 layers of drywall)- so I don't think the acoustical treatment companies that build legitimate products need to worry.



Wow, those look expensive! But what a brilliant concept!


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17008608
> 
> 
> The cynic in me questions whether or not acoustical treatment companies may not have a vested interest in leaving it up in the air if FRP absorption is a good thing.



LOL, if only!










We have about _zero influence_ on the industry. Nobody gives a crap about acoustic treatment. It's all gear, more gear, and yet more gear. No bass? Buy another sub. Still not enough bass? Then buy two more subs! Still not happy? Buy a sub equalizer.










I laughed at Roger's suggestion that it's a shame we have to let people decide for themselves what they like. As I explained in another forum just this morning, there's also the issue of an "educated" listener. Many people could make the right decision if they had extended listening time in a good sounding and well-treated room. But look at the high-end audio dealer showrooms. All gear, little or no treatment. So even if you have $100k to drop on a system, its still really difficult to find a place where you can listen to a treated room and learn over time why treatment makes the sound so much better.










I'm in the wrong business. If I wanted to get rich I'd be selling gear.










--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17033760
> 
> 
> LOL, if only!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> We have about _zero influence_ on the industry. Nobody gives a crap about acoustic treatment. It's all gear, more gear, and yet more gear. No bass? Buy another sub. Still not enough bass? Then buy two more subs! Still not happy? Buy a sub equalizer.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I laughed at Roger's suggestion that it's a shame we have to let people decide for themselves what they like. As I explained in another forum just this morning, there's also the issue of an "educated" listener. Many people could make the right decision if they had extended listening time in a good sounding and well-treated room. But look at the high-end audio dealer showrooms. All gear, little or no treatment. So even if you have $100k to drop on a system, its still really difficult to find a place where you can listen to a treated room and learn over time why treatment makes the sound so much better.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm in the wrong business. If I wanted to get rich I'd be selling gear.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



A fellow HT enthusiast and I went about 2 years ago to a dealer in the Reading area to hear a $150,000 Marantz system that was traveling around the country. "Underwhelming" got a new meaning that day; the sound was a mile high, but an inch deep. The showroom was carpeted, but otherwise all glass and drywall. WTF? Were we expected to be swayed by the price tag? Unfortunately, I'm sure some were.


Gear is a commodity, acoustical treatments are a specialty. I have great respect for you and Terry and all of the others on this thread that make a living at the latter.


----------



## Dennis Erskine




> Quote:
> Buy another sub.



No, no, no. Buy 5000 subs!


----------



## Weasel9992




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17034674
> 
> 
> No, no, no. Buy 5000 subs!



























Frank


----------



## Dennis Erskine

Ok...some anal dude just busted my chops via email on that. The actual purchase would be 4999 since there's already one sub in the room. Jeeze people.


----------



## glaufman




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17040342
> 
> 
> Ok...some anal dude just busted my chops via email on that. The actual purchase would be 4999 since there's already one sub in the room. Jeeze people.



Gotta tell us who that was so I can put him on an ignore list...


----------



## Rade1949

Hi, I'm new to the AVS Forum and to the discussion of room treatments. Have been reading this forum for the last couple of days and find it very interesting and also very confusing. I've been to several web pages offering different treatments but haven't seen any discussion on this forum regarding the *Cathedral Sound Room Dampening Panels*. Different idea, these panels mount in the upper corners where the walls meet the ceiling, are only 11 x 16 x 2 and only cost $179. for a pair. They claim they are better than the 4'-6' panels at treating standing waves and have a primary effect on mid-base and deep-base response below 200 Hz. They deal with something called the "Venturi Effect" I can't post the site (Newbie) but you can search Google and find them through Ultrasystem.

There also a couple of reviews that seem to indicate they work very well. Does anyone have any experience with these or has tried them? Thanks.

--Ron


----------



## Ethan Winer




> Quote:
> Originally Posted by *Rade1949* /forum/post/17042906
> 
> 
> haven't seen any discussion on this forum regarding the *Cathedral Sound Room Dampening Panels* ... Does anyone have any experience with these or has tried them?



Yes, I tested them and they don't work for various reasons including their size which is way too small to have any effect on bass frequencies. Proof below. The top graph pair shows the room with and without the panels. No change. The second graph pair shows the room with three half-filled garbage cans as a "control," and that actually did improve the room a little. The photo below shows one of the garbage cans.


--Ethan


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17043520
> 
> 
> Yes, I tested them and they don't work for various reasons including their size which is way too small to have any effect on bass frequencies. Proof below. The top graph pair shows the room with and without the panels. No change.
> 
> ...



I see a big change in the second low frequency resonance at around 70 Hz, Ethan. The upper graph resonance (with panels?) damps out more quickly, by more than 50 ms over the 28 dB decay range. There are other differences, but this is the most obvious one.


I'm not suggesting that this constitutes proof that these panels work. Only that I *do* see a change in the two graphs.


- Terry


----------



## Rade1949

Interesting to note that these were "recommended" by Robert Deutsch of "Stereophile" and highly recommended by Moreno Mitchell of "Stereo Times" The site selling them also includes a Tech. Info. page with their own graph showing a marked reduction in standing waves under 40Hz. This can be found at ultrasystem.com and then linking to the Cathedral Sound acoustic page. I can't post the page until I have more posts. Thanks for the info.

---Ron


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17043939
> 
> 
> I'm not suggesting that this constitutes proof that these panels work. Only that I *do* see a change in the two graphs.



Agreed, though that hardly makes them what I'd consider "effective." Especially compared to the garbage cans that had much more effect and at many more of the peak frequencies.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *Rade1949* /forum/post/17045073
> 
> 
> Interesting to note that these were "recommended" by Robert Deutsch of "Stereophile" and highly recommended by Moreno Mitchell of "Stereo Times"



Well, hi-fi reviewers recommend all kinds of things that science-minded folks know is nonsense. Like replacement power supply fuses, cable elevators, and a "demagnetizer" for your vinyl records and CDs.



> Quote:
> The site selling them also includes a Tech. Info. page with their own graph showing a marked reduction in standing waves under 40Hz ... I can't post the page



Here you go:

http://www.ultrasystem.com/usfeature...sTechInfo.html 


I'll go out on a limb and call BS because I know my tests are valid, and I have no evidence that their's are valid. Initially, they had a third party test their panels, and the "with" graphs were exactly the same as the "without" graphs except the overall level was different. So it seemed that the ringing was reduced with the panels even though nothing changed. I had several email exchanges with some of the Cathedral people, and they admitted to me they have no idea how to test their own products. That's why they sent them to me to test! Anyway, this is what _used to be_ on the Cathedral Panels web site:











If they don't even know how to run room measuring software, how could they have done "extensive scientific investigation" in the first place?










The new graph is not believable either because _nothing_ that size could make the improvement shown, even if it absorbed 100 percent at 40 Hz and below. Unless they had maybe 40 of them in the room.


IMO, people who sell stuff like this should not even try to use "science" to make their points. They should stick with the usual subjective prose you see for $1,000 replacement AC power cords and bags of magic pebbles.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17040342
> 
> 
> Ok...some anal dude just busted my chops via email on that. The actual purchase would be 4999 since there's already one sub in the room. Jeeze people.



Wow....how funny.


Frank


----------



## Rade1949

If they don't even know how to run room measuring software, how could they have done "extensive scientific investigation" in the first place?










The new graph is not believable either because _nothing_ that size could make the improvement shown, even if it absorbed 100 percent at 40 Hz and below. Unless they had maybe 40 of them in the room.


IMO, people who sell stuff like this should not even try to use "science" to make their points. They should stick with the usual subjective prose you see for $1,000 replacement AC power cords and bags of magic pebbles.


--Ethan[/quote]


Thanks for taking the time to respond, Ethan. As a newbie, that's exactly why I asked about these panels ... appreciate it!

--Ron


----------



## Weasel9992




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17049242
> 
> 
> The new graph is not believable either because _nothing_ that size could make the improvement shown, even if it absorbed 100 percent at 40 Hz and below. Unless they had maybe 40 of them in the room.



+1. That's just not credible at all.


Frank


----------



## Ethan Winer




> Quote:
> Originally Posted by *Rade1949* /forum/post/17064733
> 
> 
> Thanks for taking the time to respond, Ethan. As a newbie, that's exactly why I asked about these panels ... appreciate it!



There are many "acoustic" products that are way too small to possibly be useful. This is one of the most egregious examples because it's so expensive ($3,500):

http://www.synergisticresearch.com/?p=195 


Common sense tells us that something the size of a golf ball cannot possibly affect room acoustics, yet people buy them anyway. Then they post in audio forums how much better the sound became.










--Ethan


----------



## cuzed2

Ethan;


Kind of like 10K$ speaker wires


----------



## erkq

Magnets, warmth and liquidity... magical thinking comes to room treatment.


----------



## Weasel9992




> Quote:
> Originally Posted by *cuzed2* /forum/post/17066074
> 
> 
> Kind of like 10K$ speaker wires



So you're saying they *don't* work?










The example Ethan posted above is one of my favorites.


Frank


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17066054
> 
> 
> Common sense tells us that something the size of a golf ball cannot possibly affect room acoustics, yet people buy them anyway.



Well, you could stick them in your ears!


----------



## Weasel9992




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/17066350
> 
> 
> Well, you could stick them in your ears!



Yep...firmly duct tape them to both sides of your head.










Frank


----------



## Tonmeister2008




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17034674
> 
> 
> No, no, no. Buy 5000 subs!



Dennis I know you are kidding but I thought I would let people in on the joke who don't know the background.


Todd Welti simulated in Matlab the effect of 5,000 subs versus 4 subs on reducing the seat-to-seat variance in the predicted low frequency magnitude response, after a manufacturer suggested that everyone needs 5000 subs for a perfect in-room response at every seat. There is a point of diminishing returns in controlling room modes through destructive interference after adding 4 subwoofers. But for the high-end, discerning, sociable audiophile with many friends (probably an oxymoron), 5,000 subs will probably be the only satisfactory solution for multiple seat listening rooms --- as long as they are Harman subs, of course









The AES paper is here :


----------



## KNKKNK

I've been looking at trying to aesthetically incorporate wooden membrane absorbers as the inner panels in a wainscot.


However the information here:
http://www.ethanwiner.com/basstrap.html 

seems to size the panels at ~ 2'x8'


My question is, if the panels were only 2' x 4' (wainscot insert) would they still be effective at helping to tame the lower bass?


Ie will the reduced diaphragm size inhibit vibrations to the point that the panel is ineffective


Thanks

Brad


----------



## Ethan Winer




> Quote:
> Originally Posted by *KNKKNK* /forum/post/17066910
> 
> 
> if the panels were only 2' x 4' (wainscot insert) would they still be effective at helping to tame the lower bass?



Yes, they'll work, and will be exactly half as effective as traps twice as tall having twice the surface area. If they were only 1 foot square, that might restrict the panel motion enough to not work well. But at 2x4 the wood is large enough to flex and absorb.


--Ethan


----------



## cuzed2




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17066161
> 
> 
> So you're saying they *don't* work?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The example Ethan posted above is one of my favorites.
> 
> 
> Frank



I just checked out that link - and am shaking my head at what I have been missing; Tesla cable, Tibetan "singing" prayer bowls....?


Priceless....What was that famous WC Fields quote? "There's one born every minute"?


----------



## pepar




> Quote:
> Originally Posted by *cuzed2* /forum/post/17067633
> 
> 
> I just checked out that link - and am shaking my head at what I have been missing; Tesla cable, Tibetan "singing" prayer bowls....?
> 
> 
> Priceless....What was that famous WC Fields quote? "There's one born every minute"?



That was P.T. at least according to the urban myth.


----------



## cuzed2

Pepar,


You are correct. My bad...


----------



## Weasel9992




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17066740
> 
> 
> But for the high-end, discerning, sociable audiophile with many friends (probably an oxymoron)...



























I think I just wet myself a little.


Frank


----------



## Dennis Erskine




> Quote:
> What was that famous WC Fields quote?



It was ... edited to socially acceptable standards ...


"Don't drink the water my boy, fish **** in it."


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/17067653
> 
> 
> That was P.T. at least according to the urban myth.



Yup. But Fields did say, "You can't cheat an honest man. Never give a sucker an even break or smarten up a chump," in his movie with part of this quote as the title.


Though OT, one of my favorite Fields quotes is from "The Bank Dick."


Fields (as Egbert Sousé): "Was I in here last night and did I spend a twenty dollar bill?"

Bartender (played by sometimes Stooge Shemp Howard): "Yeah."

Fields (breathing a sigh of relief): "What a load that is off my mind. I thought I'd lost it."


----------



## tlogan6797

and don't forget "Who put this lemonade in my lemonade?"


More apt I think is that WC had a movie called "Never Give A Sucker An Even Break." So as long we're selling you 10K cables, we might as well sell you the signing bowls, too.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17078569
> 
> 
> Yup. But Fields did say, "You can't cheat an honest man. Never give a sucker an even break or smarten up a chump," in his movie with part of this quote as the title.



Well, Terry, you smarten a lot of us chumps on this thread.


----------



## cuzed2

I knew WC would fit in here ...


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/17078665
> 
> 
> Well, Terry, you smarten a lot of us chumps on this thread.



Thanks, pepar.


----------



## Roger Dressler




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17066740
> 
> 
> The AES paper is here:



I think that link has expired. No?


----------



## Dennis Erskine

The paper may still be found on the Harman site.


----------



## Roger Dressler




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17084322
> 
> 
> The paper may still be found on the Harman site.



I would find that unusual, as AES does not allow open distribution of their copyrighted papers. Harman may have cooked an alternative paper with similar content, however. Mayhaps, do you have a link? Harman's website is pretty extensive, yet gives zero hits for a search on "Welti."


BTW, I have the paper, but I cannot post it, either. Just wanted to make a ref to it in another thread.


----------



## LarryChanin




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/17085171
> 
> 
> I would find that unusual, as AES does not allow open distribution of their copyrighted papers. Harman may have cooked an alternative paper with similar content, however. Mayhaps, do you have a link? Harman's website is pretty extensive, yet gives zero hits for a search on "Welti."
> 
> 
> BTW, I have the paper, but I cannot post it, either. Just wanted to make a ref to it in another thread.



Hi Roger,


I couldn't find any papers by searching their website, but I found this "hidden" summary paper by googling.

Subwoofers: Optimum Number and Locations 


Larry


----------



## Speedskater

That's strange, I read that paper from that site Thursday.


----------



## Dennis Erskine

The "paper" that Larry found, is not the original from the site. I have that one but if Harman has taken it down, I'm not about to go sending in about.


So guys...suck it up...pay for the AES paper. Perhaps if enough buy it mine and Roger's dues will go down.


----------



## Tonmeister2008




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/17082098
> 
> 
> I think that link has expired. No?



You're right: that link is dead. This link for the Welti-Devantier paper on subwoofer optimization works for me. If it doesn't work, go the Technology Section of Harman's web site, click on the link "Scientific Publications" under the header "Technology Leadership" and you will find 20 AES papers written by Harman scientists and engineers that you can download for free.


We negotiated a yearly fee with AES that allows us to have audiophiles download these 20 papers. I am in the process of updating this list of 20 papers for the upcoming year - so if there are any Harman AES papers you'd like to see posted - let me know.


----------



## cavchameleon




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17091052
> 
> 
> You're right: that link is dead. This link for the Welti-Devantier paper on subwoofer optimization works for me. If it doesn't work, go the Technology Section of Harman's web site, click on the link "Scientific Publications" under the header "Technology Leadership" and you will find 20 AES papers written by Harman scientists and engineers that you can download for free.
> 
> 
> We negotiated a yearly fee with AES that allows us to have audiophiles download these 20 papers. I am in the process of updating this list of 20 papers for the upcoming year - so if there are any Harman AES papers you'd like to see posted - let me know.



Thanks a lot for the link Sean - and for allowing these interesting paper downloads, great reading!!!


Ray


----------



## sdurani




> Quote:
> Originally Posted by *Tonmeister2008* /forum/post/17091052
> 
> 
> We negotiated a yearly fee with AES that allows us to have audiophiles download these 20 papers.



Much appreciated. Truly.


----------



## CJO

Wow, Sean, that's great! Thanks for the link.


CJ


----------



## Ictusbrucks

I have some GIK Tri-Traps that I need to hang up in the corners overhead. I'm still trying to decide how to mount them.


The acousticalsurfaces.com website has pictures of some clips they call "EC Clips / EZ Clips" but they do not offer them for sale from their storefront that I can see.




















These look EXACTLY like what I want, but I cannot find any products that look similar either googling or at the hardware store.


Can somebody help me out? Is there a generic name for this type of metal clip system? Should be pretty easy to find right?


Any other creative ways of suspending a tri-trap overhead? They will still be oriented vertically but there will be nothing underneath. I think two clips like the ones above on either side would work well.... if I can find them.


----------



## Ictusbrucks

ok I found something similar here, but looks like it will push things further off the wall than the one from acousticalsurfaces:

http://zbarhanger.com/7to50zbarha.html 


might just call acousticalsurfaces and see if theyll sell just the hanger.


----------



## Terry Montlick

Look at these:

http://www.monarchmetal.com/pages/panelclip.html


----------



## MikeWojcik

Looking for some advice given my theater room's smallish size / plans.

It is 12 x 17.5 x 8 with a 11" sofit around the back and side walls. Sheetrocked all around including ceiling. Under my kitchen addition surrounded with concrete walls except for a 36" doorway into the main part of the basement. 2 rows of seating, rear about 1 foot from the rear wall, front 6.5 from rear wall.


I was planning on a 7.2 TRIAD silver in-wall system that will likely run around $9K. Will I be able to realize the potentially better sound over say a more affordable inwall speaker system that costs half that (e.g. Atlantic Technology)?

Am concerned that equalization and acoustic room treatements won't be enough...


Thanks in advance for your thoughts here.

Mike


----------



## pepar

Only one suggestion: Put a thick absorber on the rear wall behind the heads of the people in the rear row. Or eliminate the rear row.


----------



## Papajin




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/17101530
> 
> 
> Can somebody help me out? Is there a generic name for this type of metal clip system? Should be pretty easy to find right?



They seem fairly similar in concept to a french cleat. Same with the other ones you and Terry posted as well. No clue if they're exactly the same or not though.

http://www.hooksandlattice.com/cleat-hangers.html


----------



## Elill




> Quote:
> Originally Posted by *Papajin* /forum/post/17103456
> 
> 
> They seem fairly similar in concept to a french cleat. Same with the other ones you and Terry posted as well. No clue if they're exactly the same or not though.
> 
> http://www.hooksandlattice.com/cleat-hangers.html



Why not just use some split battens? cheaper, easier to install/get level


----------



## Roger Dressler




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17103021
> 
> 
> I was planning on a 7.2 TRIAD silver in-wall system that will likely run around $9K. Will I be able to realize the potentially better sound over say a more affordable inwall speaker system that costs half that (e.g. Atlantic Technology)?
> 
> Am concerned that equalization and acoustic room treatements won't be enough...



I'd be hard pressed to tell you that the Atlantic IWCB-626s wouldn't serve just as well as the Triads in this case. They both are in boxes, and that's essential.


Your room is a virtual clone of mine (diagram at the bottom of this post ). 11.5' x 17' x 8' with soffits all round, 13" riser, rear ears 27" from rear wall, front ears 6.5' from rear. I avoided using recliners so I could keep the seat rows a little closer.


I went with four B&W CWM8180 as their driver compliment better matched the Aerials up front, and I built the back boxes. Not sure I'd do that again, but they do sound great, running zero EQ on the rears.


----------



## pyro2003

any forum members have experience about these decorative sound absorbers, they look quite nice but I'm not sure of their acoustic performance for 2-channel music; seems to be used for classrooms and workspaces for reducing echo, flutter and clarify voice



I am thinking about this in a 12x10x8 room and mostly on the ceiling...


----------



## Ethan Winer

From that site:



> Quote:
> Designed to be used as lightweight sound absorber in the upper frequency range (500 Hz and above).



Stereo and home theater rooms need absorption that is effective all the way down to the bass range, so those panels are not suitable.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *pyro2003* /forum/post/17106062
> 
> 
> any forum members have experience about these decorative sound absorbers, they look quite nice but I'm not sure of their acoustic performance for 2-channel music; seems to be used for classrooms and workspaces for reducing echo, flutter and clarify voice
> 
> 
> 
> I am thinking about this in a 12x10x8 room and mostly on the ceiling...


 These will work.


----------



## KNKKNK




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17067292
> 
> 
> Yes, they'll work, and will be exactly half as effective as traps twice as tall having twice the surface area. If they were only 1 foot square, that might restrict the panel motion enough to not work well. But at 2x4 the wood is large enough to flex and absorb.
> 
> 
> --Ethan



Ethan.. thanks tons for the reply.


When you say it will be 1/2 as effective.. is it safe to assume that it means it aborbs 1/2 the "Amount" ie.. 2 X 2x4 membranes are as effective as 1 2x8.

Or does this mean that it is only effective in 1/2 frequency the range?


Sorry for being dense.









Brad


----------



## FoSheezy

Hello Acoustic experts and enthusiasts. I need your help!

I have created a thread with my situation, pics, ect and could use some acoustic treatment advice.
http://www.avsforum.com/avs-vb/showt...3#post17115283


----------



## Ethan Winer




> Quote:
> Originally Posted by *KNKKNK* /forum/post/17111698
> 
> 
> When you say it will be 1/2 as effective.. is it safe to assume that it means it aborbs 1/2 the "Amount" ie.. 2 X 2x4 membranes are as effective as 1 2x8. Or does this mean that it is only effective in 1/2 frequency the range? Sorry for being dense.



Actually, that's a great question and not dense at all. You'll have half the total amount of sabins in the room, where one sabin (unit of absorption) is equal to a one square foot open window. There is some overlap though. By having only half the absorption you'll have less affect on the lowest frequencies. Related, I once did a comparison of 12 traps three inches thick, versus only six traps that were each six inches thick. I was interested mainly in the role of material density on absorption, and this comparison was just an extra test for fun. The results are here if you care:

Density Report 


I'll give away the ending: 12 thinner traps worked better and to a lower frequency.


--Ethan


----------



## EAS




> Quote:
> Originally Posted by *Ictusbrucks* /forum/post/17101638
> 
> 
> ok I found something similar here, but looks like it will push things further off the wall than the one from acousticalsurfaces:
> 
> http://zbarhanger.com/7to50zbarha.html
> 
> 
> might just call acousticalsurfaces and see if theyll sell just the hanger.



Lowes has the Hangman products.

http://www.lowes.com/lowes/lkn?actio...373&lpage=none 


The beauty of the french cleat with a full angle is that if you mount it to the object correctly the angle can pull the item tight to the wall with it's weight.


----------



## pyro2003




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17108863
> 
> 
> From that site:
> 
> 
> 
> 
> Stereo and home theater rooms need absorption that is effective all the way down to the bass range, so those panels are not suitable.
> 
> 
> --Ethan



thanks Ethan


I've been looking at diffusion+absorption treatments for the ceiling that looks nice, have you tested the Bastoni ceiling panels, the idea looks like it may work :

http://www.asc-hifi.com/in-celing-bastoni.htm 


geoff


----------



## jjmbxkb

A quick question:


I am trying to determine what to do with my front corners for bass traps. The 17" sided (24" across) super chunks would be too big as the space is limited. So:


- Can I make one with 12" sides (17" across)? Will that be very ineffective to make it even not worth it?


- Will I get better results by just hanging bass trap panels on the two adjacent walls?


Thanks.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pyro2003* /forum/post/17131183
> 
> 
> have you tested the Bastoni ceiling panels



No, but even if I did I wouldn't comment because it's not appropriate for me to talk about products from a competing vendor. I can tell you that ASC is a top notch company who makes great stuff.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *jjmbxkb* /forum/post/17132542
> 
> 
> The 17" sided (24" across) super chunks would be too big as the space is limited.



Anything is better than nothing, but it's common to angle panels a little off 45 degrees to make then fit. Or put a panel flat on the wall _near_ the corner.


--Ethan


----------



## glaufman




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17135727
> 
> 
> No, but even if I did I wouldn't comment because it's not appropriate for me to talk about products from a competing vendor. I can tell you that ASC is a top notch company who makes great stuff.
> 
> 
> --Ethan



An expert, who doles out his knowledge, and classy too?


Applause.


----------



## MikeWojcik

I am working through the details of my acoustic treatments for my 12x17.5x8 dedicated theater room. One item that I've read in several threads is the use of the riser as a bass trap by stuffing the riser "bays" with acoustic material and then drilling holes (2" mentioned) in the end of each bay facing the screen.

Possibly also leaving a few inches uncovered by plywood at the wall/riser corner boundary.


How effective is such a riser trap, and is it a broadband bass trap or one that is tuned to control the frequency that's absorbed based on the hole sizes and locations? If tuned, how would one translate resonant frequencies to hole size?


Thanks in advance for the feedback

Mike


----------



## cinema mad




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17156536
> 
> 
> I am working through the details of my acoustic treatments for my 12x17.5x8 dedicated theater room. One item that I've read in several threads is the use of the riser as a bass trap by stuffing the riser "bays" with acoustic material and then drilling holes (2" mentioned) in the end of each bay facing the screen.
> 
> Possibly also leaving a few inches uncovered by plywood at the wall/riser corner boundary.
> 
> 
> How effective is such a riser trap, and is it a broadband bass trap or one that is tuned to control the frequency that's absorbed based on the hole sizes and locations? If tuned, how would one translate resonant frequencies to hole size?
> 
> 
> Thanks in advance for the feedback
> 
> Mike



What your talking about is A Helmholtz Resonator tuned for the low freq's AKA bass trap.. These type of traps are'nt broadband by nature but you can design them to work over an acceptable bandwidth or just add more aimed at different freq...


These type of treatments are good for fine tuning such as ultra low freq absorbtion/room modes, but it is better to first treat the room with BroadBand absorbtion, say in the corners on the rear wall and first reflection points inc ceiling ...


Hope this helps,

Cheers....


----------



## rec head

Without getting into drilling holes and such into the riser I would like to know if in general you would fill any such structure with fiberglass?


----------



## CJO

Definitely! If you look at my thread, there are plans for the construction of a riser from an article written by Dennis Erskine. I've also thrown in a few additions that have come up in the years since the article was written.


CJ


----------



## Roger Dressler




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17156536
> 
> 
> One item that I've read in several threads is the use of the riser as a bass trap by stuffing the riser "bays" with acoustic material and then drilling holes (2" mentioned) in the end of each bay facing the screen. Possibly also leaving a few inches uncovered by plywood at the wall/riser corner boundary.
> 
> 
> How effective is such a riser trap, and is it a broadband bass trap or one that is tuned to control the frequency that's absorbed based on the hole sizes and locations? If tuned, how would one translate resonant frequencies to hole size?



You might ask Dennis Erskine about this, as it is one of his specialties. Here's just one example.


----------



## KB1

Hi all,


I'm in the process of doing some light remodeling in my finished basement to accommodate a 2 channel audio/home theater setup. I have a very old popcorn drop ceiling that I want to replace with either standard commercial or residential Armstrong ceiling tiles. They seem to come in a variety of NRCs, from 0.4 to 0.65 (they also have some high absorption acoustic tiles that I am not considering). Given that my basement is fully carpeted, I was concerned about making the room too dead if I installed ceiling tiles that have a high absorption factor. I seem to recall that some people on this forum recommend against treating a ceiling. My basement is about 16' x 17' and it is busy, bookshelves, etc. Other than the front wall, I won't have too many flat, bare surfaces. I just don't want to make a mistake by ordering tiles that have too much of an absorption coefficient. Thanks in advance for any feedback!


----------



## Ethan Winer

You want as much absorption as possible at the ceiling reflection points. Elsewhere on the ceiling matters less. However, high absorption at bass frequencies is good around the perimeter, near the wall-ceiling corners above the grid.


Making a room dead is not as big a risk as making it dead at only mid and high frequencies.


--Ethan


----------



## pyro2003




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17135727
> 
> 
> No, but even if I did I wouldn't comment because it's not appropriate for me to talk about products from a competing vendor. I can tell you that ASC is a top notch company who makes great stuff.
> 
> 
> --Ethan



my architect suggests that I do a double gypsum ceiling with space between with fibreglass stuffed inside, this seems to be a primarily sound insulation technique and the absorption I see are typically not very high in the 200-500 Hz range, would I be wasting money (it'll cost around $1300 USD) ?


after reading around a bit, I appreciate more and more polycylinder diffusors, especially spherical like ones as they seem to work in quite a few directions and wide angles like 120 degrees (e.g. Saturn); if I find a shape that is visually acceptable I want to end up going this way...


----------



## KB1




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17171135
> 
> 
> You want as much absorption as possible at the ceiling reflection points. Elsewhere on the ceiling matters less. However, high absorption at bass frequencies is good around the perimeter, near the wall-ceiling corners above the grid.
> 
> 
> Making a room dead is not as big a risk as making it dead at only mid and high frequencies.
> 
> 
> --Ethan



Thanks Ethan. So if I proceed with replacing the entire ceiling with 0.5 NRC (let's say) ceiling tiles and also take care of the corners, it would generally be ok? Not too much absorption throughout?


----------



## Ethan Winer




> Quote:
> Originally Posted by *pyro2003* /forum/post/17175287
> 
> 
> my architect suggests that I do a double gypsum ceiling with space between with fibreglass stuffed inside... would I be wasting money (it'll cost around $1300 USD)?



I'm not much of an isolation expert so I'll let others comment. But do you even need sound isolation? Generally, construction that increases sound isolation makes the bass response worse inside the room. So unless you have sleepy and/or crying babies elsewhere in the house, I'd skip the extra isolation and put the funds into better acoustics inside the room.



> Quote:
> after reading around a bit, I appreciate more and more polycylinder diffusors, especially spherical like ones as they seem to work in quite a few directions and wide angles like 120 degrees



I'm not a fan of polys, at least not in most home-sized rooms. I think they're more useful in much larger spaces. For smaller rooms I always recommend QRD type diffusors. This video lets you hear a variety of surface types close-up:

All About Diffusion 


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *KB1* /forum/post/17177341
> 
> 
> So if I proceed with replacing the entire ceiling with 0.5 NRC (let's say) ceiling tiles and also take care of the corners, it would generally be ok? Not too much absorption throughout?



It seems to me a better solution is to use a lesser amount of highly absorbing materials. The problem with "semi-absorbing" materials is the absorption may not be uniform across the audible range.


--Ethan


----------



## KB1




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17177747
> 
> 
> It seems to me a better solution is to use a lesser amount of highly absorbing materials. The problem with "semi-absorbing" materials is the absorption may not be uniform across the audible range.
> 
> 
> --Ethan



ok, very useful advice, thank you.


----------



## cinema mad




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17177733
> 
> 
> I'm not much of an isolation expert so I'll let others comment. But do you even need sound isolation? Generally, construction that increases sound isolation makes the bass response worse inside the room. So unless you have sleepy and/or crying babies elsewhere in the house, I'd skip the extra isolation and put the funds into better acoustics inside the room.
> 
> 
> 
> 
> I'm not a fan of polys, at least not in most home-sized rooms. I think they're more useful in much larger spaces. For smaller rooms I always recommend QRD type diffusors. This video lets you hear a variety of surface types close-up:
> 
> All About Diffusion
> 
> 
> --Ethan



You make An Exellent point Ethan, that Floyd Toole makes mention in his new book as well about the not so well documented down side of room isolation IE: 2/3 layers of dry wall, as it can have an adverse effect on the low freq response due to the walls being made stiff/rigid.. Thus more $$$ then needed for Acoustic treatment & the same can be said for concrete walls....


Cheers...


----------



## Elill




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17177733
> 
> 
> I'm not a fan of polys, at least not in most home-sized rooms. I think they're more useful in much larger spaces. For smaller rooms I always recommend QRD type diffusors. This video lets you hear a variety of surface types close-up:
> 
> All About Diffusion
> 
> 
> --Ethan



Hi Ethan,


I cannot access your video at the moment....stupid work firewalls. Would you mind explaining breifly why you dont like polys in smaller rooms and why QRD is better. Or alternatively point me to a reference I can look up/read that might explain it.


I had more or less decided on polys for my room (mainly becuase they look good and are easy to make







), I would very much appreciate your views.


Also, if QRD's are the way to go, is DIY considered at all possible or just too hard for the "simple minded" to get right?


Many thanks,

Elill


----------



## cinema mad

Nothing is perfict inc Quadratic Residue Diffuser's but What makes well designed QRD diffusers superior to Polys is the favorable uniform pattern in which QRD's diffuse/scatter compared to poly's...


DIY 1D QRD's are of course possible but keep in mined that there are many different types of sequences of numbers 7 prime 11 prime, 13 prime, 17 prime,and then there are 2D primitive root "skyline's" and so on..


Small 1D shallow 7 prime seed diffusors are usefull for mid/high freq, taming flutter Echo.

If you wanted to diffuse A very wide freq range using standard QRD, the QRD Diffusor would be huge some wells as deep as 6ft or more.. This is where Wide band Diffractal type diffusors are the better choice in A smaller room due to there smaller compact size but are extremely complexed to make....


I must admit having made some 1D's myself, Good QRD's are very time consuming complexed to construct... I look & construct them like they are A prosition instrument, but I have made 7 prime QRD's and wideband 13prime 7" deep x30" wide x 4ft 2" high (Abffusors) Absorbtion and Diffusion in one ...


Cheers...


----------



## Terry Montlick




> Quote:
> Originally Posted by *cinema mad* /forum/post/17181721
> 
> 
> Nothing is perfict inc Quadratic Residue Diffuser's but What makes well designed QRD diffusers superior to Polys is the favorable uniform pattern in which QRD's diffuse/scatter compared to poly's...



This is what I thought for a long time. The theory of Schroeder diffusers is so elegant, they perform well, and they look so cool.










However, there are two factors that ultimately limit diffuser performance -- depth and regular periodicity. The first controls the lowest frequency they can scatter, and the second the uniformity of diffusion and the absence of "lobing."


But guess what? These issues are the same for both polycylindrical diffusers and Schroeder diffusers. And if you look at the performance of an individual poly vs. and individual QRD or other Schroeder diffuser, a poly or similar convex curve covers a wider frequency range and is more uniform at normal incidence. Depending on the circumstances, I recommend both types in my consulting practice.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17182296
> 
> 
> This is what I thought for a long time. The theory of Schroeder diffusers is so elegant, they perform well, and they look so cool.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> However, there are two factors that ultimately limit diffuser performance -- depth and regular periodicity. The first controls the lowest frequency they can scatter, and the second the uniformity of diffusion and the absence of "lobing."



How low is diffusion needed in rooms the size of the typical home theater?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Elill* /forum/post/17179874
> 
> 
> Would you mind explaining breifly why you dont like polys in smaller rooms and why QRD is better. Or alternatively point me to a reference I can look up/read that might explain it.



This is something you really need to hear for yourself. If you just read articles, or look at scattering data, polys look like they'd do a fine job. And they do scatter sound. But they don't reduce the hollow boxy sound of comb filtering nearly as well IMO. It seems to me the real value of QRD diffusors is the staggered reflection times due to the varying well depths more than the actual scattering.


When you get home you can see the All About Diffusion video. Another video that's closely related and worth watching / hearing is Hearing is Believing .


--Ethan


----------



## Weasel9992

Jeff Hedback wrote a great article on diffusion that addresses some of these questions pretty directly.


Frank


----------



## KERMIE




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17135735
> 
> 
> Anything is better than nothing, but it's common to angle panels a little off 45 degrees to make then fit. Or put a panel flat on the wall _near_ the corner.
> 
> 
> --Ethan



Ethan, are you saying that these would work to cut a 2' x 4' of rigid so that one side doesn't stick out as far into the room?


----------



## Elill




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17185082
> 
> 
> This is something you really need to hear for yourself. If you just read articles, or look at scattering data, polys look like they'd do a fine job. And they do scatter sound. But they don't reduce the hollow boxy sound of comb filtering nearly as well IMO. It seems to me the real value of QRD diffusors is the staggered reflection times due to the varying well depths more than the actual scattering.
> 
> 
> When you get home you can see the All About Diffusion video. Another video that's closely related and worth watching / hearing is Hearing is Believing .
> 
> 
> --Ethan





> Quote:
> Originally Posted by *Weasel9992* /forum/post/17185497
> 
> 
> Jeff Hedback wrote a great article on diffusion that addresses some of these questions pretty directly.
> 
> 
> Frank



This is a most useful discussion, thankyou both.


I need to pull my finger out and start working up detailed plans. Once this is done and I start my new construction thread. I'd be delighted if you can provide more "feedback" at this point.


In the interim I'm going to have to find somewhere that has both types of diffusers to experiment with....unfortunately it seems to be a cottage industry in Sydney.


----------



## pyro2003

Sorry, am I missing something about diffusion on the bass end ? From reading Ethan's article, very low frequency diffusion seems to miss the point, as bass response polar plot shows 

An acoustic consultant that I'm talking to, has this to say about Poly versus QRD diffusion for ceiling deployment (I'm in a 10'x18' room, sitting on the 18' side :


"... due to their (QRD diffusors) dependence on phase relationships, QRDs tend to exhibit beaming effects at higher frequencies, where more sound energy is reflected at certain sets of angles. These frequencies in turn depend on their design and construction. The most common applications are in the rear wall of a studio control room, which is normally some distance behind the listening position or in the front wall behind the speakers. The beaming effect is less pronounced at this distance from the QRD and it still gives an overall sense of diffusion after considering the direct sound from the speaker and other room reflections.


However, when suspended from the ceiling of a small apartment, the listener is closer to the QRD in relation to the speaker and beaming effects may still be prominent. This can potentially give rise to a sound-field that will vary significantly with position.


A 'Polycylindrical diffusor' relies on a curved surface to provide treble diffusion. While it may be a less efficient diffuser at certain frequencies, its effects are more even across the frequency range and less dependent on distance from the listener. It also provides more bass absorption in the sub-250Hz range, which is important for an apartment with limited space and a comfortable listening environment can be achieved with less of the potential issues of QRDs. If you are only going to get ceiling panels, Polycydrindrical are a more well-rounded solution.


Diffusion is only one aspect of room acoustics. A room with excessive diffusion will also lose some of the "liveliness" and "sense of space" that comes from well-controlled reflection patterns. This is less desirable in a studio control room where the emphasis is on accurate spatial reproduction for monitoring purposes, especially where stereo mixing is being carried out, but these qualities make for a better listening room."


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/17186223
> 
> 
> Ethan, are you saying that these would work to cut a 2' x 4' of rigid so that one side doesn't stick out as far into the room?



I wouldn't use less fiberglass. All I meant is to change the angle as needed to avoid a door or window. A 24" wide panel straddling a corner impinges about 19 inches in both directions. If you change the angle it will extend less in one direction and more in the other.


--Ethan


----------



## cinema mad




> Quote:
> Originally Posted by *Elill* /forum/post/17186418
> 
> 
> This is a most useful discussion, thankyou both.
> 
> 
> I need to pull my finger out and start working up detailed plans. Once this is done and I start my new construction thread. I'd be delighted if you can provide more "feedback" at this point.
> 
> 
> In the interim I'm going to have to find somewhere that has both types of diffusers to experiment with....unfortunately it seems to be a cottage industry in Sydney.



The larger QRDs/Abffusors I built go for around $2000au each here in Auss for A simmlar commercially built RPG Abffusor...


----------



## MikeWojcik

Looking for some advice on where to purchase materials. I live in central New Jersey and have no problems driving an hour or 2 for a good price.


I'll be looking to purchase about 150 square feet of 4" OC703, 60 square feet of 2" OC703, and 80 square feet of 1" linacoustic.


I found a web site, readyacoustics.com that sells the OC703 for $80 for 3 2x4 sheets of 4" and $80 for 6 2x4 sheets of 2". Are those good prices?


Thanks

Mike


----------



## pepar




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17192214
> 
> 
> Looking for some advice on where to purchase materials. I live in central New Jersey and have no problems driving an hour or 2 for a good price.
> 
> 
> I'll be looking to purchase about 150 square feet of 4" OC703, 60 square feet of 2" OC703, and 80 square feet of 1" linacoustic.
> 
> 
> I found a web site, readyacoustics.com that sells the OC703 for $80 for 3 2x4 sheets of 4" and $80 for 6 2x4 sheets of 2". Are those good prices?
> 
> 
> Thanks
> 
> Mike


 http://www.spi-co.com/directory.html 


These are insulation products from the HVAC/construction world. Once the word "acoustics" is attached to them, the price goes up. Contact the branch closest to you and get a quote to compare.


----------



## KERMIE




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17189570
> 
> 
> I wouldn't use less fiberglass. All I meant is to change the angle as needed to avoid a door or window. A 24" wide panel straddling a corner impinges about 19 inches in both directions. If you change the angle it will extend less in one direction and more in the other.
> 
> 
> --Ethan



Ethan, that was kind of what I was checking on. If I cut a 2' x 4' piece in those angles and stack them where one side is short then the other I think we are on the same page.


thanks


----------



## Ethan Winer

^^^ Ah, okay, you mean apply the same "angle theory" to a solid fill design. Yes, that's great.


--Ethan


----------



## Jerry Parker

I have a large living room, the dimensions are approximately 20 feet by 25 feet. The ceilings are vaulted, and approximately 15 feet tall at the top. My dining room is directly attached to the back of the room and open, so it extends another 12 feet, and is around 15 feet wide. All of the flooring is porcelain tile. The walls are covered with wood paneling that has been painted over. The ceiling is sheetrock.


As you can see, all of these factors contribute to a very live, reverberant space. I recently purchased the house, and before I moved any furniture in, it was pretty much an echo chamber in my living room. Now, with furniture and a rug, it is slightly better, but still way too reverberant for serious music/movies listening.


I was planning on making some absorbers out of either R19 or R30 fiberglass. Basically I would take a 4'x8' sheet of 1/4" mdf, and frame it about 4 inches tall, then stuff it full of fiberglass, and cover it with fabric. I would mount them to the ceiling (which is a popcorn ceiling so anything looks better than that), and the side walls.


Would 4 of these make a big difference? I would probably need to install some bass traps too, but I would like to get rid of the terrible echo first.


----------



## sage

Just a quick note on a homemade bass trap(s) I did ("made" is too strong of a word). I haven't been thrilled with the (lack of) effect of some of the commercially available traps. I purchased bales of non-itch, cellulose insullation designed to be blown into ceiling cavities. The bales are wrapped in plastic, and relatively dense; they were about 11.39 per at home depot (I'm sure there are better prices available). They weigh about 15 or 20 pounds each, and are about 25" x 15" x 18" (not exact -- from memory) I taped the seams on the bales, then stacked them angled across the front and rear corners in my room, and obscured them. I measured quite a significant difference on bass down to about 40 hz. The only mode it didn't help with was the one I have at 18hz, but I'm not surprised about that. Net cost was about $70. WAF was good once they were obscured, as this is a semi-dedicated room. I'm pretty sure it would get a no-go in the living room. :=)


----------



## glaufman

pix?


----------



## Jacob B

I posted this as a separate thread, but I guess it belongs in here...


AFter searching the archives for answers, I came up short. The older threads seem to deal with insulation rather than room acoustics.

*Why do people recommend OSB vs. plywood for floating subfloor, besides the price? And what about cement reinforced gypsum floor boards?*


My concerns are low freq absorbtion (room acoustics) as well as sound insulation.


My construction thoughts are (attic HT room above bedrooms - ceilings below are decoupled from joists):

*1.*

- wooden planks subfloor on the joists (cavities filled with rockwool)

- rubbermat 10 mm (~3/8") (isolgomma R10, european brand)

- (GG??)

- 1/2" wood

- GG

- 1/2" wood

- carpet

*OR*

*2.*

- wooden planks subfloor on the joists (cavities filled with rockwool)

- rubbermat 10 mm (~3/8") (isolgomma R10, european brand)

- (GG??)

- 1/2 " cement reinforced gypsum boards

- GG

- 1/2 " cement reinforced gypsum boards

- carpet

Thoughts on Gypsum vs. wood:

Gypsum boards are heavier thus better for low freq insulation, however also less flexible and therefor less absorbing (I think?). In other words, I might have an acoustic penalty for getting better sound insulation...?

Thoughts on OSB vs. plywood:

OSB is cheaper and a little heavier, thus better sound insulation; however, I read somewhere that the multiple layers in plywood creates better absorbtion and less low freq resonans, thus better low freq room acoustics...?

Thoughts on T&G OSB/plywood vs. non-T&G:

Using T&G osb/plywood makes it easier to lay vs. screwing the two layers of OSB/plywood together (GG in between) and using acoustic chalk to seal the seams. However, wouldn't it make the top layer (T&G) act as one big resonater rather than many smaller plates- and isn't that worse for room acoustics?


I appreciate any answer and help, but please state your knowledge level vs. hearsay







(i.e. DE or BP answers will hold higher value to me







)

Added::

My local wood supplier said today that he wouldn't recommend plywood for any kind of floating floor/subfloor, due to the tension in the wood. He said it would be difficult to control it - even if using T&G plywood. He recommended using chipboard as it is completely dead. Any thoughts on this issue?



Thanks!!!!


Jacob

Attic HT in progress


----------



## KERMIE

Does FSK or Scrim make a difference if it is on the back wall behind seating?


----------



## Ethan Winer

^^^ Yes, you do not want anything reflective on a wall that's right behind listeners.


--Ethan


----------



## KERMIE

Sorry guys, should have stated my question better.


Does FSK or Scrim make a difference if it is on the bottom half of the back wall behind seating but below ear level.


----------



## Ethan Winer

^^^ Below ear level is a good place for FRK/FSK because that gives more bass absorption in the wall-floor corner.


--Ethan


----------



## Jacob B




> Quote:
> Originally Posted by *Jacob B* /forum/post/17222958
> 
> 
> I posted this as a separate thread, but I guess it belongs in here...
> 
> 
> AFter searching the archives for answers, I came up short. The older threads seem to deal with insulation rather than room acoustics.
> 
> *Why do people recommend OSB vs. plywood for floating subfloor, besides the price? And what about cement reinforced gypsum floor boards?*
> 
> 
> My concerns are low freq absorbtion *(room acoustics)* as well as sound insulation.
> 
> 
> My construction thoughts are (attic HT room above bedrooms - ceilings below are decoupled from joists):
> 
> *1.*
> 
> - wooden planks subfloor on the joists (cavities filled with rockwool)
> 
> - rubbermat 10 mm (~3/8") (isolgomma R10, european brand)
> 
> - (GG??)
> 
> - 1/2" wood
> 
> - GG
> 
> - 1/2" wood
> 
> - carpet
> 
> *OR*
> 
> *2.*
> 
> - wooden planks subfloor on the joists (cavities filled with rockwool)
> 
> - rubbermat 10 mm (~3/8") (isolgomma R10, european brand)
> 
> - (GG??)
> 
> - 1/2 " cement reinforced gypsum boards
> 
> - GG
> 
> - 1/2 " cement reinforced gypsum boards
> 
> - carpet
> 
> Thoughts on Gypsum vs. wood:
> 
> Gypsum boards are heavier thus better for low freq insulation, however also less flexible and therefor less absorbing (I think?). In other words, I might have an acoustic penalty for getting better sound insulation...?
> 
> Thoughts on OSB vs. plywood:
> 
> OSB is cheaper and a little heavier, thus better sound insulation; however, I read somewhere that the multiple layers in plywood creates better absorbtion and less low freq resonans, thus better low freq room acoustics...?
> 
> Thoughts on T&G OSB/plywood vs. non-T&G:
> 
> Using T&G osb/plywood makes it easier to lay vs. screwing the two layers of OSB/plywood together (GG in between) and using acoustic chalk to seal the seams. However, wouldn't it make the top layer (T&G) act as one big resonater rather than many smaller plates- and isn't that worse for room acoustics?
> 
> 
> I appreciate any answer and help.
> 
> Added::
> 
> My local wood supplier said today that he wouldn't recommend plywood for any kind of floating floor/subfloor, due to the tension in the wood. He said it would be difficult to control it - even if using T&G plywood. He recommended using chipboard as it is completely dead. Any thoughts on this issue?
> 
> 
> 
> Thanks!!!!
> 
> 
> Jacob
> 
> Attic HT in progress



Please, if anyone have good advice on this acoustic issue, I would really appreciate it!

I would like to have the floor done this week, so I need to make a decision soon.


Thanks!!


Jacob


----------



## nathan_h




> Quote:
> Originally Posted by *Jacob B* /forum/post/17255520
> 
> 
> Please, if anyone have good advice on this acoustic issue, I would really appreciate it!
> 
> I would like to have the floor done this week, so I need to make a decision soon.
> 
> 
> Thanks!!
> 
> 
> Jacob



You are right in wondering whether better isolation means worse acoustics in the room. Or, rather, you are right that that is the trade off. Once you have stopped noise from coming into the room, further isolation to reduce all vibrations from leaving the room tend to make the room itself less ideal, acoustically.


----------



## R Harkness

Hey folks,


I am employing various strategies at cutting down light reflections from my wall back to my projection screen. Most of the room is dark; the wall is light and pretty reflective (no, I can't paint it for various reasons). I'm using curtains to cover a lot of the wall are when watching a movie. However I still have a large reflection point on the wall right were my surround speaker is sitting.


What I'd like to do is use a roller shade hidden up in the ceiling above that portion of the wall, and pull it down when watching a movie. However that would be pulling the shade material right over the surround speaker. Therefore I'm looking for an acoustically transparent shade material.


Any suggestions?


I took a look at a local shade store and some of their black semi-transparent shades seem very promising: dark enough to cut down the light walls. The material isn't made to be speaker-grill-like per se, but it is a very open weave, more open than most speaker grill cloth I've seen, and in the "speak-through" and "blow through" test appears to me to be very transparent.

Think it will work, or is there some more fiddly factors that go into a speaker grill clothe/acoustic cloth that makes them better?


There's also the question of the fact the speaker would end up with two sets of "grill cloth" in front of it (the one it comes with and the shade that will drop in front of it). Ought I expect muffled sound at all?


Thanks,


----------



## Jacob B




> Quote:
> Originally Posted by *nathan_h* /forum/post/17257624
> 
> 
> You are right in wondering whether better isolation means worse acoustics in the room. Or, rather, you are right that that is the trade off. Once you have stopped noise from coming into the room, further isolation to reduce all vibrations from leaving the room tend to make the room itself less ideal, acoustically.



Thanks! That still leaves me in the dark on choosing subfloor material..










Jacob


----------



## CJO

Lacking an opinion from a pro, personally, I would use option 1 with T&G OSB and no Green Glue between the rubber and first layer of OSB.

*1.
*- wooden planks subfloor on the joists (cavities filled with rockwool)

- rubbermat 10 mm (~3/8") (isolgomma R10, european brand)

- 1/2" T&G OSB

- GG

- 1/2" T&G OSB

- carpet


----------



## Jacob B




> Quote:
> Originally Posted by *CJO* /forum/post/17259128
> 
> 
> Lacking an opinion from a pro, personally, I would use option 1 with T&G OSB and no Green Glue between the rubber and first layer of OSB.
> 
> *1.
> *- wooden planks subfloor on the joists (cavities filled with rockwool)
> 
> - rubbermat 10 mm (~3/8") (isolgomma R10, european brand)
> 
> - 1/2" T&G OSB
> 
> - GG
> 
> - 1/2" T&G OSB
> 
> - carpet



Thanks  But why?


Jacob


----------



## Dennis Erskine




> Quote:
> Once you have stopped noise from coming into the room, further isolation to reduce all vibrations from leaving the room tend to make the room itself less ideal, acoustically.



How's that?



> Quote:
> Thanks  But why?



Why what? No GG between mat and first layer of OSB? or why OSB?


----------



## CJO

My thoughts- Green Glue is most effective when placed between surfaces of relatively equal rigidity, so it won't do much good between the rubbermat and OSB. T&G OSB is the easiest flooring material and I doubt that using the other materials would make any substantial difference in the sound isolation. If you are still concerned, just add another layer of Green Glue and T&G OSB.


One quick thought- you may want to run the additional dead load for the rubbermat and possible extra layer of OSB on the floor by your structural engineer.


Also, since you are paying so much attention to the sound isolation for the floor, make sure that you pay equal attention to any flanking paths for sound.


CJ


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17259333
> 
> 
> How's that?
> 
> 
> 
> 
> Why what? No GG between mat and first layer of OSB? or why OSB?



Dennis E and CJO,

Understand no GG between rubbermat and OSB and why that is.

However, the acoustic part of the question is still left unanswered and I hope that Dennis might be able to help here










=> Won't T&G OSB make each OSB layer act like basically one big sheet (rather than 12 smaller sheets)?

What will that do to the room acoustics vs. no T&G, 1/8" of space on all four sides between each 2' x 4' OSB sheet and acoustic sealant in this empty space.

Besides making the floor more stable, what will it do to the acoustics, theoretically?


I don't think the different solutions will be that different sound insulation wise, but I have a feeling the acoustic impact will be different.

So the question still is, FOR ROOM ACOUSTICS, why OSB vs. the two other materials? And what will T&G do for acoustics?


Thanks a bunch










Jacob


----------



## Dennis Erskine

Simple answer. No difference.


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17260613
> 
> 
> Simple answer. No difference.



Hi Dennis,

No in-room acoustic difference for both questions? (i.e. T&G vs. not?, and OSB vs. cement reinforced gypsum/drywall boards vs. plywood?)


Jacob


----------



## pepar




> Quote:
> Originally Posted by *Jacob B* /forum/post/17261214
> 
> 
> Hi Dennis,
> 
> No in-room acoustic difference for both questions? (i.e. T&G vs. not?, and OSB vs. cement reinforced gypsum/drywall boards vs. plywood?)
> 
> 
> Jacob



I'd be very surprised if any tests have been conducted on these comparisons. Unless you consider softening footfalls acoustical treatments, floating floors are used for reasons other than room acoustics. Many times they are used over a concrete slab and/or below grade though they can be designed to help isolate the room itself and reduce transmission to adjacent spaces. Mostly though, from my experience, they are used on a slab. I am in the flooring biz.


----------



## Dennis Erskine




> Quote:
> No in-room acoustic difference for both questions?



yup.


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17262185
> 
> 
> yup.



@Pepar

I am aware that the mat mainly will work for impact noise.

However, I will have butt-kickers installed in the riser as well as the two center seats of the first row (Berkline 090). The riser will have sound insulating rubber feets - but still.

*@Dennis E*

I still don't understand that the laminar material of the floor won't impact the absorption properties and therefore the in-room acoustics










I read on a HIFI dedicated forum (danish) that floor construction was very important in regard to avoiding the floor playing along (resonating). The author recommended as many (different) laminar layers as possible to get different structural resonance points, with less amplitude/volume as result:

http://www.hifi4all.dk/content/templ...d=366&zoneid=2 

Using translate.google (edited for major misunderstandings, but not grammar etc







):

"When the room is playing along

In principle, a floor is not much different from a speaker cabinet acoustic set. The idea is that the floor's contribution must be minimized - ie that ideally you should absolutely not be able to feel vibrations in the floor regardless of the frequencies and sound pressure, there is. As with everything else, the ideal state in practice impossible to achieve.
So what is possible and how?

A little common sense can quickly weed out larger floor plates, since they are very difficult to curb. Just as at the cabinet manufacturing and all other products that should not have natural frequencies, the best results are obtained when laminating materials with individual oscillation patterns - preferably with as little surface as possible, as less resonansamplituder means lower volume .. Just the fact that the amplitude must be minimized means that large floor plates require an extraordinary effort in relation to attenuation.

Completely different is the situation with parquet flooring, which is composed of a multitude of small parquets. The best parquets are actually already laminated to a variety of materials and as such constitutes a sound basis for a well dampened. The problem with parquet flooring is that it must be put together. The assembly of the parquet floor is crucial to the final acoustic result regardless of the insulation to the floor. Parquet exist in principle in two versions: The floors are glued together and they are not glued together. It is the logic of ducks that they glued types are clearly the best, then click floors are naturally plenty of air in between sessions and the edges from rubbing against each other. Do you have a click-floor you can be advantageously either glue it together or put a 1-2 mm silicone-line in the lower half of the session if the floor must be dismantled later. The glue must be made so that all contact surfaces are covered with a thin layer.
The subfloor

The subfloors are very different and depends on the individual building design. The hardest cases are older apartments, where wooden floors are often based on a kind of beams, which lies between the levels. It is a huge task to tackle, and the results are seldom targets of such efforts.

Many houses and newer apartment buildings have a concrete deck as a subfloor.

The most ideal solution to floor problems will be to make the best recording studio - namely to make the entire listening space "float" in an acoustic isolation from the building's permanent structure. However, it is not so easy in an ordinary home, and even these floating listening rooms can be very difficult to construct. The idea of constructing a good listening environment is, of course, to get sound energy is converted into heat at selected locations instead of uncontrolled resonances. Even the best designs can be extremely difficult to channel the energy in the sound on to selected points where it can be converted to energy.

At home with concrete deck the trick, therefore, is to transfer sound energy in floors, insulation and concrete deck in an ideal relationship. With the laminated parquet is much already won because laminate is able to convert large amounts of energy to heat, as each layer restricts another's own structural resonance as opposed to a single layer floor.

Even a perfectly sized, laminated parquet is not without side effects since the total area of the parquet floor in principle represents a giant "membrane" which - ceteris paribus - has its own movement pattern with their own overtones. In practice this means that the entire "cone" has a peculiar resonance, while parts of the floor can have its own resonances of larger or smaller areas, depending on the floor adaptation to space, furnishings, etc. The total floor self resonance is almost never a problem because the resonance often very low, and it can be subdued to inaudible by heavy furniture, etc.. It is the - if I may say so - local resonances, which can cause small problems. Here comes the decoupling or insulation between the floor and into the substrate and the task now is to keep logic in check, since relaying a glued floor will be a headless deed. You therefore need to think of energy transmission when you insulate under your floor. Rule No. 1 is that sound energy must not be translated into movements in the floor. The energy not converted into heat in the lamination in Parkett, must therefore continue down the insulation. The energy not converted in the insulated cavity must ultimately be transferred to the concrete deck. It had been wonderful if concrete deck just grabs the last amount of energy. All know that concrete virtually no potential for oscillation. Unfortunately, concrete largely return energy back where it came from. With a well insulated and laminated parquet floor will again be allocated energy in isolation and parquet albeit in much smaller quantities than the other way.

The [rubber or similar mat] insulation has a major responsibility for the final result. Again, laminating is the answer. An insulation consisting of multiple, suitable materials will translate various energy pathways to heat - just like laminating parquet floor. By choosing a laminated insulation can save several cm insulation, compared with an insulation consisting of only one material. I take one only 8 mm thick lamination of 2 mm rubber while the last 6 mm and consists of 3 different filter types plus the obligatory water-damp sealant layer at the bottom"


Any comments from the experts?

















Jacob


----------



## pepar




> Quote:
> Originally Posted by *Jacob B* /forum/post/17264719
> 
> 
> Any comments from the experts?



The comment from this non-expert is that you are over-thinking this.


----------



## Weasel9992




> Quote:
> Originally Posted by *Jacob B* /forum/post/17264719
> 
> 
> Any comments from the experts?



I know it's hard to believe, but Dennis is right. I'm not aware of any specific testing aside from material absorption properties, and the differences tend to fall within the error range given the sample sizes.


Frank


----------



## Jacob B




> Quote:
> Originally Posted by *pepar* /forum/post/17265320
> 
> 
> The comment from this non-expert is that you are over-thinking this.










That's me.









However, I think the majority of the population find us (here on avsforum) to fit That description









Jacob


----------



## pepar




> Quote:
> Originally Posted by *Jacob B* /forum/post/17265464
> 
> 
> 
> 
> 
> 
> 
> 
> That's me.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> However, I think the majority of the population find us (here on avsforum) to fit That description
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jacob



That's true. And humor is the antidote.


----------



## R Harkness

Can anyone reply to this post:

http://www.avsforum.com/avs-vb/showt...5#post17257675 


What kind of acoustic-transfer properties do I need to look for in a roller screen material that will drop down in front of my side FX speaker?


Thanks,


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/17266311
> 
> 
> Can anyone reply to this post:
> 
> http://www.avsforum.com/avs-vb/showt...5#post17257675
> 
> 
> What kind of acoustic-transfer properties do I need to look for in a roller screen material that will drop down in front of my side FX speaker?
> 
> 
> Thanks,



You might be breaking new ground here. I would think that the obvious would be what to look for - something acoustically transparent.


Maybe look at what companies are using for masking systems for AT screens . . .


----------



## Dennis Erskine

It appears to me you already have the answer you're looking for. You actually have two; but, it appears you want to get tied up in knots over laminates and adhesives on flooring material.


----------



## R Harkness




> Quote:
> Originally Posted by *pepar* /forum/post/17266500
> 
> 
> You might be breaking new ground here. I would think that the obvious would be what to look for - something acoustically transparent.
> 
> 
> Maybe look at what companies are using for masking systems for AT screens . . .



Obviously I'm looking for something as acoustically transparent as possible.

The problem is speaker grill cloth doesn't normally come on roller shade mechanisms and you can't just put any material on a roller - typical grill cloth material is too stretchy to roll up and down reliably.


Therefore...since I have to go into non-speaker-cloth territory, most likely what one can find within the offerings from roller shade companies, what types of roller shade materials might I look at that could fit the bill? I know they will come in varying levels of "openness" meant mostly in terms of light transfer, but I wondered if any of the experts could chime in as to whether there are roller shade materials that could work. Perhaps someone - for instance a custom installer here - is familiar with, say a shade with an openness rating of 3 or 5 or 10 and can advise as to whether any of those ought to be suitably acoustically transparent?


Thanks.


(If need be I'll check out what some companies are using for AT masking)


----------



## pepar




> Quote:
> Originally Posted by *R Harkness* /forum/post/17267613
> 
> 
> Obviously I'm looking for something as acoustically transparent as possible.
> 
> The problem is speaker grill cloth doesn't normally come on roller shade mechanisms and you can't just put any material on a roller - typical grill cloth material is too stretchy to roll up and down reliably.
> 
> 
> Therefore...since I have to go into non-speaker-cloth territory, most likely what one can find within the offerings from roller shade companies, what types of roller shade materials might I look at that could fit the bill? I know they will come in varying levels of "openness" meant mostly in terms of light transfer, but I wondered if any of the experts could chime in as to whether there are roller shade materials that could work. Perhaps someone - for instance a custom installer here - is familiar with, say a shade with an openness rating of 3 or 5 or 10 and can advise as to whether any of those ought to be suitably acoustically transparent?
> 
> 
> Thanks.
> 
> 
> (If need be I'll check out what some companies are using for AT masking)



Hmmm, now I'm thinking the material that is used in woven AT _*screens*_ might be the ticket. Can't remember the name of the generic stuff off hand, but it is inexpensive. In real life, it is shade cloth.


But they will know about it in the DIY Screen forum . Sheerweave something or other...


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17266697
> 
> 
> It appears to me you already have the answer you're looking for. You actually have two; but, it appears you want to get tied up in knots over laminates and adhesives on flooring material.



Dennis,

When I read something like the post on the linked Danish HiFi forum, and I don't know the CV of the poster, I look for second opinions. And normally, being a scientist, I look for answers backed by research. Second best is best practice/experience supported by theoretical explanations.

However, I acknowledge this might not be possible in all cases - this included - but I always try, nevertheless.

I think you will find that is the general case in most of the area discussions on the forum.

I don't post a lot, but I have been reading for 8 years know. That solves most of my questions.

When I post, it's because I cannot find the answer in the achives. Or if I think I can contribute. As my post number shows, neither happens very often










I appriciate answers by experienced persons like yourself, and hope you don't take offense when I ask the 'WHY's









I also accept that answering the why might not be possible or just not practical time wise - as posting here probably doesn't pay your rent










Best regards,

Jacob


----------



## pepar




> Quote:
> Originally Posted by *Jacob B* /forum/post/17268529
> 
> 
> 
> I appriciate answers by experienced persons like yourself, and hope you don't take offense when I ask the 'WHY's
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I also accept that answering the why might not be possible or just not practical time wise - as posting here probably doesn't pay your rent



What about his posts lead you to that conclusion?


----------



## Jacob B




> Quote:
> Originally Posted by *pepar* /forum/post/17268961
> 
> 
> What about his posts lead you to that conclusion?



Well, Dennis' last reply seemed to indicate that he was wondering why I kept asking when he already had answered:
_"It appears to me you already have the answer you're looking for. You actually have two; but, it appears you want to get tied up in knots over laminates and adhesives on flooring material."_

So I felt the need to explain that I really like to know the "WHYs"









I understand that an explanation might not be available and, but that Dennis answers from his vast experience in acoustic designs of rooms

- but I would also accept if he knew the theoretical explanation but felt it would take too long to write it - time he didn't want to spend and his experience told him his answer was correct anyway.


Anywhy, I will use the suggested: acoustic mat - OSB T&G - GG - OSB T&G.


Cheers,

Jacob


----------



## Dennis Erskine

What field of science, Jacob?


----------



## glaufman




> Quote:
> Originally Posted by *pepar* /forum/post/17268344
> 
> 
> Hmmm, now I'm thinking the material that is used in woven AT _*screens*_ might be the ticket. Can't remember the name of the generic stuff off hand, but it is inexpensive. In real life, it is shade cloth.
> 
> 
> But they will know about it in the DIY Screen forum . Sheerweave something or other...



Didn't think to test it, but I saw rollup shades in HD today with a perforated fabric that just might work for you.


----------



## JapanDave

Just a question that maybe Dennis or any other experts could help me with.


I have a room that is 20.1ft long X 16.4ft wide and 7.7ft high, all walls and ceiling are 10" concrete, the floor is 18" thick with one heavily soundproofed door.


I am currently researching on how I should go about treating this room acousticly. I am carpeting the room and using an underlay of some sort, other than that I am not sure how I should approach this room. I understand that the base is what is going to give me problems and of coarse bass traps will be used but this is not going to solve everything.


Any help would be appreciated.


----------



## rec head

What did that room used to be?


----------



## JapanDave




> Quote:
> Originally Posted by *rec head* /forum/post/17277504
> 
> 
> What did that room used to be?



Fish room, I had 23 fish tanks including 1 X 18ft (1200g) and 3 X 8ft(400g) tanks, all together over 10,000g of water with tanks from other rooms included. I moved those tank to another room and decided to make a HT. The whole house is solid concrete with the walls ,floors, ceilings all 10" thick. The base of the house has two sections where the floor is 18" and 36" thick. Have to build for earthquakes here.


----------



## erkq




> Quote:
> Originally Posted by *JapanDave* /forum/post/17277586
> 
> 
> The whole house is solid concrete with the walls ,floors, ceilings all 10" thick. The base of the house has two sections where the floor is 18" and 36" thick. Have to build for earthquakes here.



Holy crap, we have to build for earthquakes here too. But a wood frame house with engineered shear strength, proper bolted foundation, tie downs, strapping, etc. do the trick. What size earthquake is the house supposed to survive? a 9? a10??


----------



## JapanDave




> Quote:
> Originally Posted by *erkq* /forum/post/17277606
> 
> 
> Holy crap, we have to build for earthquakes here too. But a wood frame house with engineered shear strength, proper bolted foundation, tie downs, strapping, etc. do the trick. What size earthquake is the house supposed to survive? a 9? a10??



It is designed to handle an earthquake bigger than the one in Kobe in 1995.　I will put it this way, Japan has one of the strickest building codes in regards to earthquakes in the world and in the Kobe earthquake out of 460,000 houses, 104,906 were completely destroyed, 144,274 were partially destroyed and 141,326 houses suffered some kind of substantial damage. Over 90% of the remaining 69,494 houses to be undamaged were solid concrete. No concrete houses were completely or partially destroyed and the ones that did suffer damage was mainly due to fires and other buildings around them causing the damge, 1% suffered structural damge but those houses were over 70 years old. Anyway you look at it, I am not going to risk my families lives by using wood, it is just not strong enough to handle bigger earthquakes.


Sorry for the off-topic remarks, I will get back on topic now.


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17271529
> 
> 
> What field of science, Jacob?



Political science







- albeit I studied mechanical engineering for two years, ages ago.

Cheers,

Jacob


----------



## rec head




> Quote:
> Originally Posted by *JapanDave* /forum/post/17277929
> 
> 
> It is designed to handle an earthquake bigger than the one in Kobe in 1995.　I will put it this way, Japan has one of the strickest building codes in regards to earthquakes in the world and in the Kobe earthquake out of 460,000 houses, 104,906 were completely destroyed, 144,274 were partially destroyed and 141,326 houses suffered some kind of substantial damage. Over 90% of the remaining 69,494 houses to be undamaged were solid concrete. No concrete houses were completely or partially destroyed and the ones that did suffer damage was mainly due to fires and other buildings around them causing the damge, 1% suffered structural damge but those houses were over 70 years old. Anyway you look at it, I am not going to risk my families lives by using wood, it is just not strong enough to handle bigger earthquakes.
> 
> 
> Sorry for the off-topic remarks, I will get back on topic now.



WOW. I thought you were going to say a vault or something.


----------



## JapanDave




> Quote:
> Originally Posted by *rec head* /forum/post/17282045
> 
> 
> WOW. I thought you were going to say a vault or something.



LOL, it could well be made into a bunker!


----------



## BasementBob




> Quote:
> Originally Posted by *JapanDave* /forum/post/17277929
> 
> 
> It is designed to handle an earthquake bigger than the one in Kobe in 1995.　I will put it this way, Japan has one of the strickest building codes in regards to earthquakes in the world and in the Kobe earthquake out of 460,000 houses, 104,906 were completely destroyed, 144,274 were partially destroyed and 141,326 houses suffered some kind of substantial damage. Over 90% of the remaining 69,494 houses to be undamaged were solid concrete. No concrete houses were completely or partially destroyed and the ones that did suffer damage was mainly due to fires and other buildings around them causing the damge, 1% suffered structural damge but those houses were over 70 years old. Anyway you look at it, I am not going to risk my families lives by using wood, it is just not strong enough to handle bigger earthquakes.



Earthquake proof is lots more complicated than just 'build it out of concrete'.


If you're on sandy soil, like Mexico City, foundations disappear like quicksand, and concrete structures over them break.

If you're on bedrock, then minor earthquakes are often less of a problem for concrete structures, but larger earthquakes seem to magnify the damage. Concrete tends to fail suddenly and catastrophically, whereas wood bends. Coupled with steel to keep the wood together (strapping, 30' bolts, triangular-earthquake-welded-8'-wall-bracings, etc), wood may survive earthquakes that concrete would not. Steel is extremely useful structurally when it is under tension.


I was watching a disaster program the other day in which a fellow had a concrete home and a forest fire went through and it collapsed (obviously a wooden home would have collapsed faster). My friends in Europe can't believe we in North America build homes out of wood.



> Quote:
> Japan has one of the strictest building codes in regards to earthquakes



Usually nothing wrong with following building codes -- they tend to be extremely practical for each area. They're usually written due to evolution -- when something falls down, they go have a look, and come back and change the building code.


The funniest example of that that I know of is a municipality where it's legal to build a two storey structure out of manure, but not a three story structure out of manure. A three storey one fell down.


----------



## Peter M

BB,


Good summary.


It's all about ductility. Concrete is fine as long as it's suitably reinforced, particulary at the connections, to ensure appropriate levels of ductility.


Personally I prefer steel ...


----------



## citizen arcane

I now have bass trapping in the four vertical corners and 2x4 broadband panels on the two side walls of my media room. As this room is a den that gets used for socializing and the occasional movie shown with the pj; I want to add diffusion to the rear wall using a rather large floating shelf and assorted square wall cubbies.


I will add that the chairs used for watching/listening are six feet away from the rear wall so I believe I will benefit from this treatment.The question is: will I realize a markable difference in scatter/reflection adding odd sized books, vases, pictures frames angled differently from one another, etc. Any tips/tricks would be greatly appreciated!


----------



## BasementBob




> Quote:
> Originally Posted by *citizen arcane* /forum/post/17292051
> 
> 
> I want to add diffusion to the rear wall using a rather large floating shelf and assorted square wall cubbies. Any tips/tricks would be greatly appreciated!



Maintain left/right symmetry.


For diffusion, periodicity is your enemy.


The two funniest stories I've heard about using bookcases as diffusers are:

1) the fellow who put down tape under the books to mark where the books should be placed on the shelf. The tape is just hidden if the books are placed correctly. The books were purchased not for content, but such that they could be placed according to a QRD pattern, and the maid kept pushing them back against the back of the bookcase so they'd all look flat rather than the in-out style he kept leaving them in. So he put the tape down so he could fix them after the maid left each week.

2) Another fellow, also got rid of his assorted books, and instead went with stone because the book's spines were too soft to some frequencies. He then painted the stone to look like books, and ...


----------



## jvvjvv

I have visited a few other HT sites, but this thread has really been helpful.


I am getting ready to finish off my basement HT room, 8' wide x 7'6" high x 19' long. Stairs, ceiling and outside wall have dictated the size, so I am stuck with the poor width and height. I can shorted the room with a partition wall. The 3 existing wall are double 5/8 GG, then covered with 19/32 finished plywood. (3 walls are earthquake shear walls, hence the plywood).


What would be the best length for the room? The wall will be 5/8 2x4 and double 5/8 with GG between on the HT side. This will be the front wall. What is the good acoustical treatment for this wall?



What is the best treatment for the ceiling? Some say from the speakers to the seating and some the whole room.....which and what material? Double 5/8 GG is going to be the base. Would like to put ply paneling on after that.............(need to have several "trap doors" to quickly get at plumbing shut off valves). I can acoustical panel the speakers to seating area........will that work?


The floor is concrete. Carpet is said to work well, but some have said speakers to seating and others the whole room ?


The back wall can be rows of DVD's on shelving........will the be enough diffusion?


The L/R speakers are going to have to be pretty close to the walls to have some 7' between them.......they are 3' tall.........any thing "special" that can be done to make up for the short spread between them?


Thanks, Jack


----------



## Noah

This isn't strictly home theater related, as you'll see.


I've just moved to a house that's probably 1/4 mile or so from a set of train tracks. You don't so much hear the train (there are no horns/whistles) as you feel a sort of rumble in your ears. Its very low frequency.


So, until Ford stops making the infernal Ranger and shipping them within rumbling distance of my house, is there anything I can do to treat my rooms to reduce that 2 AM train rumble? DD+GG for the whole house is not a viable option.


Right now, I'm thinking the previous owner should have left me a case each of earplugs and Nyquil. The rumble doesn't wake me up, but if I'm up and the train comes by (they're slow and seem to go on for hours) getting to sleep can be difficult. On the positive side, I do catch up on my movie queue and forum browsing.


----------



## Ethan Winer




> Quote:
> Originally Posted by *jvvjvv* /forum/post/17299528
> 
> 
> What would be the best length for the room?



My Graphical Mode Calculator program suggests that making the room shorter will only be worse. Ideally you'd make the width 12 feet instead of only 8.



> Quote:
> What is the good acoustical treatment for this wall? What is the best treatment for the ceiling?



That's a big question, and not necessarily the right one. The very short answer is you need as many corner bass traps as posibile, plus absorbers at the side-wall and ceiling reflection points.



> Quote:
> The back wall can be rows of DVD's on shelving........will the be enough diffusion?



Bookshelves are not diffusors, no matter how many people might claim that on the Internet.







This video is aimed at recording studio types, but the principles apply to HT and listening rooms too:

All About Diffusion 



> Quote:
> The L/R speakers are going to have to be pretty close to the walls to have some 7' between them.......they are 3' tall.........any thing "special" that can be done to make up for the short spread between them?



You and the speakers should form an equilateral triangle as explained here:

How to set up a room 


--Ethan


----------



## JapanDave




> Quote:
> Originally Posted by *BasementBob* /forum/post/17287771
> 
> 
> Earthquake proof is lots more complicated than just 'build it out of concrete'.
> 
> 
> If you're on sandy soil, like Mexico City, foundations disappear like quicksand, and concrete structures over them break.
> 
> If you're on bedrock, then minor earthquakes are often less of a problem for concrete structures, but larger earthquakes seem to magnify the damage. Concrete tends to fail suddenly and catastrophically, whereas wood bends. Coupled with steel to keep the wood together (strapping, 30' bolts, triangular-earthquake-welded-8'-wall-bracings, etc), wood may survive earthquakes that concrete would not. Steel is extremely useful structurally when it is under tension.
> 
> 
> I was watching a disaster program the other day in which a fellow had a concrete home and a forest fire went through and it collapsed (obviously a wooden home would have collapsed faster). My friends in Europe can't believe we in North America build homes out of wood.
> 
> 
> Usually nothing wrong with following building codes -- they tend to be extremely practical for each area. They're usually written due to evolution -- when something falls down, they go have a look, and come back and change the building code.
> 
> 
> The funniest example of that that I know of is a municipality where it's legal to build a two storey structure out of manure, but not a three story structure out of manure. A three storey one fell down.



Understood.

Let me put it this way,from the calculations of the engineer and from past experience with concrete houses in earthquakes, if the foundations were to give out on our house it would simply roll over on itside with out any structral damage. And could be reset after fixing the foundations.


The walls are filled with 13mm re-enforced steel at 4" spacing both vertically and horizontally and due to the thickness of the walls there are two rows built into every wall. And due to the fact that foundations play a big roll our house has 3ft diameter concrete filled bored holes ranging from a depth of 30-50ft, they are strategically placed and reach down to solid rock. There is not much around that is stronger than this house. I put $150K just in the foundations, but like I said before, nothing is better than piece of mind.


----------



## pyro2003

this is suppose to diffuse and absorb, are there any math way to determine the dimensions spacing etc ?


http://www.laudescher.com/images/_PDFCAT_EN_347.pdf


----------



## Ethan Winer




> Quote:
> Originally Posted by *pyro2003* /forum/post/17305571
> 
> 
> this is suppose to diffuse and absorb



That looks like it's meant for use in a large venue, which has _totally different_ requirements than a domestic listening room or home theater.


--Ethan


----------



## velvet396




> Quote:
> Originally Posted by *Noah* /forum/post/17299622
> 
> 
> This isn't strictly home theater related, as you'll see.
> 
> 
> I've just moved to a house that's probably 1/4 mile or so from a set of train tracks. You don't so much hear the train (there are no horns/whistles) as you feel a sort of rumble in your ears. Its very low frequency.
> 
> 
> So, until Ford stops making the infernal Ranger and shipping them within rumbling distance of my house, is there anything I can do to treat my rooms to reduce that 2 AM train rumble? DD+GG for the whole house is not a viable option.
> 
> 
> Right now, I'm thinking the previous owner should have left me a case each of earplugs and Nyquil. The rumble doesn't wake me up, but if I'm up and the train comes by (they're slow and seem to go on for hours) getting to sleep can be difficult. On the positive side, I do catch up on my movie queue and forum browsing.



living near a train myself, I can contest while it's weird at first, you get used to it. I'm no acoustic expert though, so GL.


----------



## pyro2003




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17307804
> 
> 
> That looks like it's meant for use in a large venue, which has _totally different_ requirements than a domestic listening room or home theater.
> 
> 
> --Ethan



probably, if nothing else though I'm using the nicer outlook and half openness to hide/expose my absorption panels and let them work, as a compromise in a typical home. From this viewpoint I think you're suggesting to ignore the spacing and thickness of wood to do anything... in fact they should be as small in total area as possible then.


Just found some equations for slat absorbers if they are considered HR

http://accucalhd.com/documents/audio...t%20Course.pdf


----------



## avare




> Quote:
> Originally Posted by *pyro2003* /forum/post/17310590
> 
> 
> Just found some equations for slat absorbers if they are considered HR
> 
> http://accucalhd.com/documents/audio...t%20Course.pdf



Nice document. Thanks for the link.


Andre


----------



## BasementBob




> Quote:
> Originally Posted by *pyro2003* /forum/post/17305571
> 
> 
> this is suppose to diffuse and absorb, are there any math way to determine the dimensions spacing etc ?



I am not an acoustician, nor do I play on on TV. And I did not even sleep at a holiday inn last night.


This is not a helmholtz absorber. It's more a variation on the 'inside out wall'.


It does have some interesting bits, although I don't think I'd ever do it this way.


1) Structurally, if someone leans against it, they lean against wood, not fabric or compressable insulation. And the wood gives a nice nailing edge to hang a picture.


2) absorptively. It's not a helmholtz absorber. It's a simple foam absorber, spread out between boards. It would be nice to see the absorption coefficients from a lab on this system. But at a guess, I'd say it's just the same as foam, with each absorption coefficient (at each frequency band) halved per surface area due to the wood spacing it out. There might be a bit of a boost due to edge defraction at some frequency band. There might be periodicity issues giving absorptive boosts to some frequencies over others.


3) defusively. The wood will provide spacial and temporal diffusion, relative to the aborptive parts. Not much since it's so long and straight. Also, the absorbers will due to edge effect warp the sound pressure at certain frequency bands and that will give a bit of a diffusive effect too. That said, unless you're very very lucky, this is not likely to be a good thing in your home theatre. Again it would be nice to see diffusive tests from a lab on this system.


4) reflectively. There's wood there. So it will reflect too. If you align the boards so that the speaker, board, ear, are in a line, then high frequency sound going slightly up or slighly down will bounce off the upper and lower parts of the boards back into the absorption. Low and mid frequency sound have wavelengths too big for this to matter. I wonder if this might make the room sound muddy (more highs absorbed than mids), from a home theatre perspective. Or if you'd luck out and get a sence of spaciousness (wouldn't bet a paycheck on that).


-----


I've often thought of putting up what would at first glance look like a slat absorber. Except that I'd have the slats too wide, and the entire cavity filled with insulation, to resonate (i.e. a setup that is so innefficient a resonator, that it wouldn't resonate, and wouldn't behave as a helmoltz slat absorber). Instead of having a peak frequency (helmoltz style), it would combine reflection and low/mid frequency absorption up to the limits of the porous absorption alone. Maybe I'll do that some day. Maybe it will behave the way I expect, and maybe it won't. But it would be a part of a whole room analysis.


----------



## LarryChanin




> Quote:
> Originally Posted by *pyro2003* /forum/post/17310590
> 
> 
> probably, if nothing else though I'm using the nicer outlook and half openness to hide/expose my absorption panels and let them work, as a compromise in a typical home.



Hi,


If you are looking for the wood paneling that disguises absorptive material you might want to research RPG's Topakustik perforated wood panels . RPG's website provides acoustical data for their various designs. I have no idea of the cost of these panels or whether RPG will even work with anyone other than professionals.


Larry


----------



## pepar




> Quote:
> Originally Posted by *LarryChanin* /forum/post/17316268
> 
> 
> Hi,
> 
> 
> If you are looking for the wood paneling that disguises absorptive material you might want to research RPG's Topakustik perforated wood panels . RPG's website provides acoustical data for their various designs. I have no idea of the cost of these panels or whether RPG will even work with anyone other than professionals.
> 
> 
> Larry



Congrats, Larry, on hitting 5k!


----------



## LarryChanin




> Quote:
> Originally Posted by *pepar* /forum/post/17316283
> 
> 
> Congrats, Larry, on hitting 5k!



Hi Jeff,


Thanks.


Now if I could just run 5k without having a coronary.










Larry


----------



## pyro2003

Thanks Larry and BasemenBob,


actually the picture use acoustic wood panels, which I found some local supply, they're either perforated or made from melamine to have specific absorption properties with only a very thin air gap


thats' a middle of the road cost way - usually it is used for entire wall in public places, schools or conference rooms - so can be too much for an entire wall in a home


----------



## citizen arcane

I have some leftover OC 705 equivalent and would like to fill the bottom of some plant stands that are in my media room. The 'glass would be semi circular 16" across, 8" deep and 22" tall to fill these spaces. All sides except for the very bottom (which would sit on a shelf) would be exposed and wrapped in GOM 701. This would be very much like GIK's elite table trap.


FWIW these stands are centered on the front wall behind the L/R mains (the placement is symmetrical); that wall is otherwise untreated besides bass traps. The side walls have mid/high absorption panels (2" 705) and the tri corners are treated with traps - floor to ceiling. The rear wall is untreated but have floating book shelves with books and knick knacks.


So I guess my question is: is there benefits in "getting as much acoustic materials you can" in the room?


----------



## pepar




> Quote:
> Originally Posted by *citizen arcane* /forum/post/17323185
> 
> 
> I have some leftover OC 705 equivalent and would like to fill the bottom of some plant stands that are in my media room. The 'glass would be semi circular 16" across, 8" deep and 22" tall to fill these spaces. All sides except for the very bottom (which would sit on a shelf) would be exposed and wrapped in GOM 701. This would be very much like GIK's elite table trap.
> 
> 
> FWIW these stands are centered on the front wall behind the L/R mains (the placement is symmetrical); that wall is otherwise untreated besides bass traps. The side walls have mid/high absorption panels (2" 705) and the tri corners are treated with traps - floor to ceiling. The rear wall is untreated but have floating book shelves with books and knick knacks.
> 
> 
> So I guess my question is: is there benefits in "getting as much acoustic materials you can" in the room?



It can't hurt, but the size doesn't seem big enough to derive any meaningful trapping from it.


----------



## Jacob B

Hi all,

After having solved the floor construction issues (see post 5251 and 5271 this thread), I am now moving on to the ceiling.


Maybe I should lay out the draft acoustic plan first (based on advice from BPape and from reading this thread):
*Room dimensions (HxWxL):* 5.5'/8.0' x 12.6'/5.0' x 21' (heights are start and end of sloping ceiling, widths are at floor and at ceiling - see attached pictures). Ceiling Joists are currently 5" high, will be 4" after DD with GG between the joists on the current parquet wooden ceiling (which lays on top of the joists and with 8" of fluffy rockwool above, on the loft)
*Speaker setup:*

- Three floor standing Audiovector M3 Signature speakers behind 110" wide 2.40:1 SMX CineWeave™ HD AT screen mounted on false wall 2½ feet from front wall - underneath joist 2 (top of screen will be 5.5' above floor due to sloping ceiling)

- SVS PB12-plus/2 subwoofer between center speaker and left or right speaker.

- 4 x MK 150 SS Tripole surround speakers

*Acoustic treatment plan (all panels will be GOM wrapped):*
*Front wall:* whole wall 2" OC703 (for balanced wall - window will be covered)
*All four vertical corners:* Bass Traps with stacked OC703 triangles 24"x17"x17" up to the start of sloping ceiling.
*Front wall / floor corner:* 12" x 12" OC703 Bass trap
*Front wall / ceiling corner:* OC703 Bass trap panel 6" x 5' x 2' (Whole area between joist 1 and 2).
*Sloping ceiling:* Panels made of 2" OC703 6"x48" with a wooden frame 3½" deep (thus 1½" of air behind the OC703), wrapped in GOM. These panels will be spaced with 8" along the whole length of the sloping ceiling (Bass absorbtion and crude diffusion)
*Side walls:* 1" OC703 panels from floor and 4' up

*Problems/considerations:*
*1)* I also need bass absorbtion at Rear wall / ceiling corner (between joist 7 and 8 counted from front wall). However, there is only 14" from ceiling down to the top of the door and the MK 150 SS Tripole rear surround speakers are 10.6" high. I think I will have to mount the rear surrounds high enough to clear the door, to get the two rear surrounds spaced far enough from each other, but also to clear the second row on a 20" riser (see rear wall picture).

This means I really can't fit more than a 3.4" thick OC703 panel above them (or 4" with small slots cut out for the two rear speakers), as they need sideroom to fire the dipoles.
*Will this be OK?*

*2)* Acoording to Bpape, I also need bass absorption (a 4-6" thick OC703 panel) overhead the seats.
*I don't know whether this should be above only the primary row of Berkline 090 (1st row) or above the second row as well?* Second row will be on a 20" riser (due to the low screen). Therefore, it would actually be nice to keep the 8' ceiling above second row for "head room" when getting seated










The 1st row will have their heads beneath 4 and 5, second row beneath joist 6 and 7.

*3) What to do with the remaining ceiling (between joist 2-3, 3-4, and 5-6)?*

I would like to make a fiber star light ceiling for the whole celing area from joist 2 to joist 8, but can I combine that with the bass absorbtion overhead 1st row (and maybe overhead second row as well) and the rear wall/ceiling panel at joist 7-8?









I studied SandmanX's star light ceiling, but that will only work for the joist 2-4 area in front of 1st row - _masonite star light panels underneath the ceiling OC703 bass absorbtion panels would defeat the purpose of the OC703, wouldn't it?_









_And what about *1st reflections* from the masonite star light panels, in the joist 2-4 area?_ I would use fluffy fiberglass to fill the cavity between joist 2-4, above the star light panels, but that doesn't cover 1st reflections, does it?










This was a lot, I know







, but I hope some of you can give a comprehensive suggestion to my ceiling construction










Thanks in advance,

Jacob


Attic Home Theater under construction


----------



## giomania

I am finally going to start my acoustic treatment installation project this weekend. I am planning to install SSC DIY traps in the front vertical corners of my theater, as well as along the horizontal intersection of the front wall and ceiling. I will then build a screen wall out from the existing front wall. I believe this is similar to Pepar's theater.


Anyway, since the SSC corner traps will be behind the screen wall, I do not see the need for a vertical strip of wood installed at the edges of the corner chunks in the vertical corners. It would seem these vertical strips of wood are typically installed to assist in covering the trap with fabric. I was thinking the wood strips might limit the edge effect?


I was thinking to just install a piece of 2" x 3" wood diagonally along the top and bottom of the vertical corners so that I can string some fishing line or wire from eye bolts to keep the stack from falling over. Here is a crude representation of what I am trying to say: TT


Any input is appreciated.


Thanks.


Mark


----------



## ExToker

While trying to get a handle on my room acoustics, I felt I should at least get somewhat of a idea of the physics of sound, absorption, reflections etc.


I've had 'The Master Handbook of Acoustics' on my nightstand for a couple months, and to say the least it is daunting to grasp the complexity of sound.


I just found this page this morning. In a nutshell I was able to somewhat grasp what is going on as it is very clear and well written.

I wanted to point it out to those with my minimal level of knowledge, like myself.

http://www.novibes.com/NoiseControl/tech_info/ntech.asp


----------



## mike0311

I have a couple of quick questions on panels. I read a great deal of this thread so I have a pretty good idea on what I'd like to do. My questions are this, for my side panels I am going to go with 1" oc703. Should the panels I make have a 1" depth or is it better to have another inch of space between the oc703 and the wall and make them 2" deep? I thought someone had said the space was good to have but I didn't find any further discussion on it. My other question is should I wrap a backing on the panels to stop the particles from escaping?


Mike


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *mike0311* /forum/post/17343841
> 
> 
> Should the panels I make have a 1" depth or is it better to have another inch of space between the oc703 and the wall and make them 2" deep?



You might want to just consider this then, instead of buidling 1 inch space covered by 1 inch of material, just go with a two inch panel. Higher density than air, and thus a bit more effective.



> Quote:
> I thought someone had said the space was good to have but I didn't find any further discussion on it.



Air is an effective absorber, but not as effective as mass...goes back to the density thing.



> Quote:
> My other question is should I wrap a backing on the panels to stop the particles from escaping?



Which particles are you referring to? Air or material? If air is what your referring to, I think you may find it a bit difficult to do that, but you are more than welcome to try.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/17343984
> 
> 
> You might want to just consider this then, instead of buidling 1 inch space covered by 1 inch of material, just go with a two inch panel. Higher density than air, and thus a bit more effective.



And simpler to mount.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *ExToker* /forum/post/17334798
> 
> 
> I've had 'The Master Handbook of Acoustics' on my nightstand for a couple months, and to say the least it is daunting to grasp the complexity of sound.



You ain't seen nothin' yet!







Just keep going in the direction you are...you'll find out.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *kal rubinson* /forum/post/17343991
> 
> 
> and simpler to mount.



+1


----------



## mike0311

SMB...Thanks for the info. I don't remember exactly who but I think it was Dennis that said the 2" was too absorbing in most cases? My theater is only about 14' wide so I'd prefer to go the 1" route unless people say it would be totally ineffective or just really a stupid idea. Also I was talking about the fiberglass particles







Also please don't take this the wrong way because I am actually asking it as a question and not trying to be sarcastic. You say that mass is a better absorber then air. I see what you are saying but wouldn't it depend upon what the mass is? I don't see putting 10" slabs of steel on the wall as being absorbent. I'm just learning this stuff so I am always eager to hear peoples advice. Thanks again.


----------



## SierraMikeBravo

Far be it from me to argue with Dennis, but IMHO, it all depends on what frequencies you are trying to target. Many have different philosphies, but I prefer to go with 2 inch myself when dealing with the lateral reflections. Not saying Dennis is wrong by any means, but it is just the way I do it, and everyone has "their way" so to speak. Also, not sure where he was referring to inch and what frequencies.


As far as the steel thing, we have to remember that we do want air to penetrate the material fairly easily.


----------



## Jacob B




> Quote:
> Originally Posted by *Jacob B* /forum/post/17324299
> 
> 
> Hi all,
> 
> After having solved the floor construction issues (see post 5251 and 5271 this thread), I am now moving on to the ceiling.
> 
> 
> Maybe I should lay out the draft acoustic plan first (based on advice from BPape and from reading this thread):
> *Room dimensions (HxWxL):* 5.5'/8.0' x 12.6'/5.0' x 21' (heights are start and end of sloping ceiling, widths are at floor and at ceiling - see attached pictures). Ceiling Joists are currently 5" high, will be 4" after DD with GG between the joists on the current parquet wooden ceiling (which lays on top of the joists and with 8" of fluffy rockwool above, on the loft)
> *Speaker setup:*
> 
> - Three floor standing Audiovector M3 Signature speakers behind 110" wide 2.40:1 SMX CineWeave HD AT screen mounted on false wall 2½ feet from front wall - underneath joist 2 (top of screen will be 5.5' above floor due to sloping ceiling)
> 
> - SVS PB12-plus/2 subwoofer between center speaker and left or right speaker.
> 
> - 4 x MK 150 SS Tripole surround speakers
> 
> *Acoustic treatment plan (all panels will be GOM wrapped):*
> *Front wall:* whole wall 2" OC703 (for balanced wall - window will be covered)
> *All four vertical corners:* Bass Traps with stacked OC703 triangles 24"x17"x17" up to the start of sloping ceiling.
> *Front wall / floor corner:* 12" x 12" OC703 Bass trap
> *Front wall / ceiling corner:* OC703 Bass trap panel 6" x 5' x 2' (Whole area between joist 1 and 2).
> *Sloping ceiling:* Panels made of 2" OC703 6"x48" with a wooden frame 3½" deep (thus 1½" of air behind the OC703), wrapped in GOM. These panels will be spaced with 8" along the whole length of the sloping ceiling (Bass absorbtion and crude diffusion)
> *Side walls:* 1" OC703 panels from floor and 4' up
> 
> *Problems/considerations:*
> *1)* I also need bass absorbtion at Rear wall / ceiling corner (between joist 7 and 8 counted from front wall). However, there is only 14" from ceiling down to the top of the door and the MK 150 SS Tripole rear surround speakers are 10.6" high. I think I will have to mount the rear surrounds high enough to clear the door, to get the two rear surrounds spaced far enough from each other, but also to clear the second row on a 20" riser (see rear wall picture).
> 
> This means I really can't fit more than a 3.4" thick OC703 panel above them (or 4" with small slots cut out for the two rear speakers), as they need sideroom to fire the dipoles.
> *Will this be OK?*
> 
> *2)* Acoording to Bpape, I also need bass absorption (a 4-6" thick OC703 panel) overhead the seats.
> *I don't know whether this should be above only the primary row of Berkline 090 (1st row) or above the second row as well?* Second row will be on a 20" riser (due to the low screen). Therefore, it would actually be nice to keep the 8' ceiling above second row for "head room" when getting seated
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The 1st row will have their heads beneath 4 and 5, second row beneath joist 6 and 7.
> 
> *3) What to do with the remaining ceiling (between joist 2-3, 3-4, and 5-6)?*
> 
> I would like to make a fiber star light ceiling for the whole celing area from joist 2 to joist 8, but can I combine that with the bass absorbtion overhead 1st row (and maybe overhead second row as well) and the rear wall/ceiling panel at joist 7-8?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I studied SandmanX's star light ceiling, but that will only work for the joist 2-4 area in front of 1st row - _masonite star light panels underneath the ceiling OC703 bass absorbtion panels would defeat the purpose of the OC703, wouldn't it?_
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _And what about *1st reflections* from the masonite star light panels, in the joist 2-4 area?_ I would use fluffy fiberglass to fill the cavity between joist 2-4, above the star light panels, but that doesn't cover 1st reflections, does it?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This was a lot, I know
> 
> 
> 
> 
> 
> 
> 
> , but I hope some of you can give a comprehensive suggestion to my ceiling construction
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks in advance,
> 
> Jacob
> 
> 
> Attic Home Theater under construction



(See post 5302 for pictures)


No one biting? Come on, shots are free


----------



## giomania




> Quote:
> Originally Posted by *giomania* /forum/post/17326327
> 
> 
> I am finally going to start my acoustic treatment installation project this weekend. I am planning to install SSC DIY traps in the front vertical corners of my theater, as well as along the horizontal intersection of the front wall and ceiling. I will then build a screen wall out from the existing front wall. I believe this is similar to Pepar's theater.
> 
> 
> Anyway, since the SSC corner traps will be behind the screen wall, I do not see the need for a vertical strip of wood installed at the edges of the corner chunks in the vertical corners. It would seem these vertical strips of wood are typically installed to assist in covering the trap with fabric. I was thinking the wood strips might limit the edge effect?
> 
> 
> I was thinking to just install a piece of 2" x 3" wood diagonally along the top and bottom of the vertical corners so that I can string some fishing line or wire from eye bolts to keep the stack from falling over. Here is a crude representation of what I am trying to say: TT
> 
> 
> Any input is appreciated.
> 
> 
> Thanks.
> 
> 
> Mark



I finished the trap installation, and wound up with a single piece of wood (2" x 3") placed verticallay in the center of the stack, wedged in tight between the ceiling and carpeted floor. I placed a single screw on an angle through a the top of the wood piece into the drywayll, just to ensure it will not fall over in the future.


Mark


----------



## giomania

I installed my 34" StudioTips Super Chunk (SSC) bass traps this weekend. Since I had plenty of JM 814, I decided to "face" the vertical corner traps with the optional "cover panel". I cut several of the 48" x 24" panels down to 34" wide by 24" high, and stacked them in front of the installed 34" triangles.


This provided a more finished appearance, but I was wondering if the factory surface of panels is more reflective than the cut edges of the triangles. I just thought I would ask.


Thanks for any input.


Mark


----------



## Jacob B

Depending on how your ceiling, walls and floor is constructed sound wise, you might want to consider the tight fit of the 2" x 3" - you normally avoid having any surface directly touching a neighbour surface for resonance reasons / noise flanking. It might not matter, though. Maybe you could use a little piece of rubber or polyerutane at each end to decouple?


As for the reflecting properties of the cut edges of the fiberglass vs the factory surface, I am pretty sure it doesn't matter for low freq - and probably not for mid and high as well. After all, the front surface is what is used for wall panels to absorb first reflections of mid and high.


Cheers,

Jacob


----------



## giomania




> Quote:
> Originally Posted by *Jacob B* /forum/post/17348161
> 
> 
> Depending on how your ceiling, walls and floor is constructed sound wise, you might want to consider the tight fit of the 2" x 3" - you normally avoid having any surface directly touching a neighbour surface for resonance reasons / noise flanking. It might not matter, though. Maybe you could use a little piece of rubber or polyerutane at each end to decouple?
> 
> 
> As for the reflecting properties of the cut edges of the fiberglass vs the factory surface, I am pretty sure it doesn't matter for low freq - and probably not for mid and high as well. After all, the front surface is what is used for wall panels to absorb first reflections of mid and high.
> 
> 
> Cheers,
> 
> Jacob




Thanks for the input. The ceiling of the room is isolated, and the floor is concrete, so I don't think the tight fit of the 2x3 is an issue. However, I had not thought of that before installing it. Regarding the reflectivity, I was thinking along the same lines as you, as the front surface is used on FRP panels.


Mark


----------



## ExToker




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/17344007
> 
> 
> You ain't seen nothin' yet!
> 
> 
> 
> 
> 
> 
> 
> Just keep going in the direction you are...you'll find out.



Thats the intimidating part. I _am_ seeing it. Building my room to preferable ratios was the easy part.


Now I'm hanging around both absorption and equalizing forums. Throw in 1 amazing book by F. Alton Everest and I got a big heaping serving of humble pie










I do have 3 things going for me though.


1. I love math

2. I crave learning

3. We got a helluva long winter just starting here in Minnesota.


I figure I should make some (a little) headway ( I hope) on this given the above.


Great people here. I'm sure I might have a question, or 2, down the road.


----------



## giomania

Here are pictures of my front wall after working this past weekend.


Mark


----------



## Jacob B

*Giomania:*What OC703 thickness do you have on the front wall itself?

*Anyone:*

Is it is better to make a SSC trap at the horizontal intersection of the front wall and ceiling or at the floor and wall intersection - if you have to choose due to lack of OC703 material....


Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??


No comments on my ceiling thoughts (post 5312)?


Thanks,

Jacob


----------



## giomania




> Quote:
> Originally Posted by *Jacob B* /forum/post/17358309
> 
> *Giomania:*What OC703 thickness do you have on the front wall itself?
> 
> *Anyone:*
> 
> Is it is better to make a SSC trap at the horizontal intersection of the front wall and ceiling or at the floor and wall intersection - if you have to choose due to lack of OC703 material....
> 
> 
> Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??
> 
> 
> No comments on my ceiling thoughts (post 5312)?
> 
> 
> Thanks,
> 
> 
> 
> Jacob



Sorry, I forgot to mention that was 2" JM 814, which is equivalent to OC 703.


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17357299
> 
> 
> Here are pictures of my front wall after working this past weekend.



Very nice, Mark!


Next up for me is to install chunk traps in the rear of the room where it will be seen. I have modified my mounting system used behind my false wall to add a GOM-covered . . cover. Over the next few weeks I will execute the plan and post pics here as well as on my site.


have you listened to your system since adding the traps???


Jeff


----------



## pepar




> Quote:
> Originally Posted by *Jacob B* /forum/post/17358309
> 
> 
> Is it is better to make a SSC trap at the horizontal intersection of the front wall and ceiling or at the floor and wall intersection - if you have to choose due to lack of OC703 material....
> 
> 
> Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??



The more you install, the better. It is difficult if not impossible to have too much/many corner chunk traps. Traps at the different wall-to-wall/ceiling/floor junctures all address different modes, so they are all good to have.


----------



## glaufman




> Quote:
> Originally Posted by *Jacob B* /forum/post/17358309
> 
> 
> Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??



IIRC, chunks perform better in any single given corner, but if material is limited, what you gain from treating more corners can outweigh what you lose by going from chunks to obliques, but YMMV depending on how many more corners you can treat due to both material and WAF concerns...


----------



## Jacob B




> Quote:
> Originally Posted by *pepar* /forum/post/17358799
> 
> 
> The more you install, the better. It is difficult if not impossible to have too much/many corner chunk traps. Traps at the different wall-to-wall/ceiling/floor junctures all address different modes, so they are all good to have.



Pepar,


Questions is, with a given number of 2" OC703 sheets, I can make a ceiling/wall *and* a floor/wall corner basstraps using 2' x 4' panels mounted _oblique_ (_with air behind the panels)_

*OR*


I can make *either*

one "solid" SCC trap at ceiling/wall
_*or*_

one "solid" SCC trap at floor/wall


Which would be better? It will be the same amount OC703 material used - just in two different ways..


Cheers,

Jacob


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/17358925
> 
> 
> IIRC, chunks perform better in any single given corner, but if material is limited, what you gain from treating more corners can outweigh what you lose by going from chunks to obliques, but YMMV depending on how many more corners you can treat due to both material and WAF concerns...





> Quote:
> Originally Posted by *Jacob B* /forum/post/17358936
> 
> 
> Pepar,
> 
> 
> Questions is, with a given number of 2" OC703 sheets, I can make a ceiling/wall *and* a floor/wall corner basstraps using 2' x 4' panels mounted _oblique_ (_with air behind the panels)_
> 
> *OR*
> 
> 
> I can make *either*
> 
> one "solid" SCC trap at ceiling/wall
> _*or*_
> 
> one "solid" SCC trap at floor/wall
> 
> 
> Which would be better? It will be the same amount OC703 material used - just in two different ways..
> 
> 
> Cheers,
> 
> Jacob



I'd go with glaufman's advice, but you should do some acoustical measuring to make the final determination.


----------



## dc_pilgrim

Just a tip for folks - a lot of the acoustic books on amazon have the "look inside" preview on amazon. If you are looking for info on specific issues, you have an opportunity to sample some of the information. This includes Floyd Toole's latest and Alton Everest's master handbook.

http://www.amazon.com/Sound-Reproduc...5614139&sr=8-1 

http://www.amazon.com/Master-Handboo..._bxgy_b_text_b 


Obviously, if these books are helping you, you should think about picking up a copy yourself.


----------



## glaufman




> Quote:
> Originally Posted by *Jacob B* /forum/post/17358936
> 
> 
> Pepar,
> 
> 
> Questions is, with a given number of 2" OC703 sheets, I can make a ceiling/wall *and* a floor/wall corner basstraps using 2' x 4' panels mounted _oblique_ (_with air behind the panels)_
> 
> *OR*
> 
> 
> I can make *either*
> 
> one "solid" SCC trap at ceiling/wall
> _*or*_
> 
> one "solid" SCC trap at floor/wall
> 
> 
> Which would be better? It will be the same amount OC703 material used - just in two different ways..
> 
> 
> Cheers,
> 
> Jacob



One interesting consideration is if you go with the obliques, how thick will they be? 2" may lose much more vs the chunks than 6"...


----------



## giomania




> Quote:
> Originally Posted by *pepar* /forum/post/17358767
> 
> 
> Very nice, Mark!
> 
> 
> Next up for me is to install chunk traps in the rear of the room where it will be seen. I have modified my mounting system used behind my false wall to add a GOM-covered . . cover. Over the next few weeks I will execute the plan and post pics here as well as on my site.
> 
> 
> have you listened to your system since adding the traps???
> 
> 
> Jeff



Thanks. What can I say...you inspired me. The only modifications was that I used those metal angle brackets, 1" x 4" wood, and then those wood "straps" to ensure the angle brackets would not bend over time.


I have not listened to it yet. I still have to build the screen wall, re-install the screen, re-position the speakers, re-calibrate with Audyssey, etc.


One thing I was wondering if the (optimal) placement of the subs in the room would change due to the treatments? I found the optimal placement by using the DD-15's built-in SMS-1 software and pushing the subs around on furniture sliders. Will I need to go through this process again?


Logically, I think the optimal placement is based on the room dimensions, and the treatments will only smooth out the room's response. If that is correct, the optimal placement exercise should not need to be re-accomplished?


Thanks for any input.


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17360517
> 
> 
> Thanks. What can I say...you inspired me. The only modifications was that I used those metal angle brackets, 1" x 4" wood, and then those wood "straps" to ensure the angle brackets would not bend over time.
> 
> 
> I have not listened to it yet. I still have to build the screen wall, re-install the screen, re-position the speakers, re-calibrate with Audyssey, etc.
> 
> 
> One thing I was wondering if the (optimal) placement of the subs in the room would change due to the treatments? I found the optimal placement by using the DD-15's built-in SMS-1 software and pushing the subs around on furniture sliders. Will I need to go through this process again?
> 
> 
> Logically, I think the optimal placement is based on the room dimensions, and the treatments will only smooth out the room's response. If that is correct, the optimal placement exercise should not need to be re-accomplished



I'd be in the "logically" camp if the original locations were optimal based solely on room dimensions, but just for kicks you might want to try the SMS thing again. And report back....


You will be amazed after you've re-done Audyssey!


----------



## MikeWojcik

Giomania


Nice clean job - what did you use on the vertical wall to hold the panels in place?

I see black circles in the pictures on each panel - what are they?


Thanks

Mike


----------



## diesel10pilot

Has anyone tried these panels?

http://www.samsclub.com/shopping/nav...&itemid=459945 


Thanks,


Mick


----------



## giomania




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17365407
> 
> 
> Giomania
> 
> 
> Nice clean job - what did you use on the vertical wall to hold the panels in place?
> 
> I see black circles in the pictures on each panel - what are they?
> 
> 
> Thanks
> 
> Mike



Thanks Mike. I used 3" drywall screws (#6) that I had, and I went to home depot to get some fender washers. I placed two screw/washer combinations in each panel, screwed into the stud. They are actually silver, since I haven't painted them black yet.


Mark


----------



## Jacob B




> Quote:
> Originally Posted by *glaufman* /forum/post/17359300
> 
> 
> One interesting consideration is if you go with the obliques, how thick will they be? 2" may lose much more vs the chunks than 6"...



I was thinking maybe 4" obliques to make the OC703 last for more corner treatment.

How about filling out the cavity behind the oblique with standard "fluffy" fiberglass?


Jacob


----------



## Dennis Erskine




> Quote:
> Far be it from me to argue with Dennis



SMB ... please feel free to disagree with me at anytime. Please remember the following three points:


1. Your exam hasn't been scored yet;

2. I know where you live; and,

3. I know the HAARP boys.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *diesel10pilot* /forum/post/17369468
> 
> 
> Has anyone tried these panels?
> 
> http://www.samsclub.com/shopping/nav...&itemid=459945
> 
> 
> Thanks,
> 
> 
> Mick



Only 1" of polyester fiber will do _something_ but not much.


----------



## citizen arcane




> Quote:
> Originally Posted by *diesel10pilot* /forum/post/17369468
> 
> 
> Has anyone tried these panels?
> 
> http://www.samsclub.com/shopping/nav...&itemid=459945
> 
> 
> Thanks,
> 
> 
> Mick



From Stereophile:


Tom Gorzelski of mytheater acoustic panel showed me his simple and inexpensive kits. Don't expect them to work into the bass, therefore, but Tom acknowledges that they are most effective at 1–2kHz


----------



## Kal Rubinson




> Quote:
> Originally Posted by *citizen arcane* /forum/post/17371752
> 
> 
> From Stereophile:
> 
> 
> Tom Gorzelski of mytheater acoustic panel showed me his simple and inexpensive kits. Don't expect them to work into the bass, therefore, but Tom acknowledges that they are most effective at 1-2kHz



So are my drapes.


----------



## pepar

I stopped at "Sam's Club."


----------



## mike0311




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17370862
> 
> 
> SMB ... please feel free to disagree with me at anytime.



So is 1" enough Dennis? If so, should I build a 2" frame so I have 1" of air between the 703 and wall?


----------



## johnbomb




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/15406068
> 
> 
> Measurement/calibration sequence.
> 
> 
> 1. With all equipment (and the HVAC on) and no sound from the speakers, produce a 1/3rd octave full range RTA. This will give you the background noise floor in the room. This will provide a boundary between what your speakers are doing and what is ambient in the room.
> 
> 
> 2. Two near field measurements of each speaker. The microphone should be placed approximately 1' meter from the face of the speaker with the microphone aimed directly at the speaker. You may need to increase the distance beween the speaker and microphone slightly if you have multiple, widely spaced drivers. The measurement should be taken using pink noise first with bass management off (no crossovers active) and secondly with bass management and cross overs active. (We like to do a series of off axis measurements as well.) The subwoofer(s) should be measured as well. The purpose of these measurements are to: (1) establish that all drivers in the speaker are working correctly; (2) to give you a baseline measurement of what the speaker is producing so during calibration you can tell room/treatment impacts from the speakers' response; and, (3) determine if bass management is working correctly (correct slopes, 3 dB down at crossover frequency, etc.).
> 
> 
> 3. With the microphone (or array) set up for the primary listening position, disconnect all but one speaker at a time, and, using full range pink noise, measure the RTA of each individual speaker. You can, at this time level match the speakers as well. Bass management should be on. These plots can be overlaid against the nearfield to provide a rather obvious display of what the room is doing to response at the seating location. Large peaks and dips above 500Hz are most likely as a result of SBIR and point to a need for treatment (diffusion and/or absorption). Typically, you use 1/12 octave, C weighted pink noise. (1/12th isnt how we hear but provides the granularity needed to see problems). At this time, run an ETG (bass management on) for each speaker. This will show you SBIR and early reflections which are problematic. Based upon the later RT60 you plot for the room, you can determine whether absorption, diffusion or a combination thereof is most appropriate (over absorption of early reflection points is a common mistake). The biggest common cause of SBIR is from the front wall (behind the speakers) and the side wall immediately adjacent to the speakers. You can avoid most SBIR problems by keeping your main speakers at least 3.5' away from any surface (assuming a crossover of 80Hz). Subs should be placed closer than 3.5' from a wall (again assuming an 80 Hz crossover).
> 
> 
> 4. Turn off all speakers but the subs (bass management on) and position the microphone in a right tricorner of the room. The peaks in this plot will show you the actual modes in the room (real, not calculated) and their relative intensity. (Again, pink noise, full range). Run measurements at the primary seating location as well as other seating locations in the room. These latter measurements will provide the modal peaks and nulls which occur at individual seating locations. You might want to look for a null which is NOT a modal frequency.
> 
> 
> 5. You now want to position your various subs to reduce, moderate or eliminate nulls at primary listening positions. This measurement is best done using spatial averaging in each individual seating location....forget about seats within about 3.5' of a wall. Various types of tuned, or broadband absorption can be used to reduce both peaks and nulls.
> 
> 
> 6. Parametric EQ can be used to terminate peaks (won't help on the nulls).
> 
> 
> 7. Run another RTA of the subs, together (1/3 octave) and bring the average SPL level of the plot up to, or down to, the same average level of your center channel (L/C/R are already level matched).
> 
> 
> It's very difficult to determine a treatment strategy until you actually measure what is happening the room. The various prediction models are not 100% accurate but certainly can provide a heads up with respect to what you might need. During calilbration and set up process, once you change something, do your measurements all over again to see what impact the change had. Also, most important...don't forget to LISTEN to your reference materials between changes.




Mr. Erskine,


First, thank you for such an informative post. I know it's a bit old, but I would very much appreciate your clarifying a few things for me, if you don't mind.


1) Won't room interference contaminate nearfield (1 meter) speaker measurements? I'm guessing you're using at least cardiod, if not super or hypercardiod mics for this test.


2) Regarding the listening position: do you average the graphs you obtain from the various positions, perhaps weighting the most favored listening position? I'm guessing omnidirectional mics are being used at each spot.


3) When "listening" with the mic in a tricorner, I'm guessing that again the mic is omnidirectional.


4) After initial room treatment, lets say I wanted to target a more narrow band of problem frequencies at the listening positions via the use of a resonating (pressure) panel trap. Would I next use a mic to "listen" along the walls/ceiling/floor to find where those frequencies are loudest, and then install the trap at that point?


All this assumes the use of sweeps from Room Eq Wizard.



Thanks very much for your time,

John


----------



## Dennis Erskine




> Quote:
> 1) Won't room interference contaminate near field (1 meter) speaker measurements? I'm guessing you're using at least cardiod, if not super or hypercardiod mics for this test.



You don't want to do this with the speakers in a corner...in the middle of the room works. What you want is to have the volume sufficiently higher than the ambient noise in the room. The FR display (short gate time) displays peak and is sufficient (reflected sound will be sufficiently below first arrival as to not skew your results for the purpose of this exercise.. If you want a near anechoic measurement, you can do this outside.



> Quote:
> 2) Regarding the listening position: do you average the graphs you obtain from the various positions, perhaps weighting the most favored listening position? I'm guessing omnidirectional mics are being used at each spot.



I cheat. I use multiple mics. You can either take multiple measurements and average them in the software or you can take a single mic, use a 6 to 10 second gate average, and keep the mic in motion around the seating location.



> Quote:
> 3) When "listening" with the mic in a tricorner, I'm guessing that again the mic is omnidirectional.



It is omni directional when oriented obliquely to the source, directional when aimed directly at the source.



> Quote:
> 4) After initial room treatment, lets say I wanted to target a more narrow band of problem frequencies at the listening positions via the use of a resonating (pressure) panel trap. Would I next use a mic to "listen" along the walls/ceiling/floor to find where those frequencies are loudest, and then install the trap at that point?



If you take a measurement in the tricorner, the peaks will show up. You can do the math to determine if those peaks are L, W, or H modal responses OR you can place the mic at the back wall to read only L modes, etc. For example, placing a diaphragmatic or pressure trap on the back wall will do nothing for a width mode. For this purpose, any particular length mode will be equally apparent anywhere along the front or back wall.


----------



## johnbomb




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17374980
> 
> 
> It is omni directional when oriented obliquely to the source, directional when aimed directly at the source.



I'm a bit confused here: when I say "omnidirectional", I'm referring to the mic's pick up pattern. If such a mic is used, then I don't see how directionality with respect to the source matters. I have a CAD 179 large diaphragm condenser mic- it's a lower end mic with a continuously variable pickup pattern whose frequency response is (IIRC) flattest in "omni" mode.


Again, thanks very much!


John


----------



## Jrek

Hello, I was hoping to get a little help,I'll be placing some corner bass traps soon and was looking for placement advise,I will eventually cover floor to ceiling but until I have enough traps for now do I place the panels on the floor stradling the corner or I have seen pictures of panels hung mid way between floor and ceiling which is the correct way to mount?Also should side wall first reflection panels be spaced away from the wall and if yes by how much? Thank you in advance Jim This is all new for me just getting invovled and reading and researching I feel like my head is going to explode. Ha Ha Again Thanks Jim


----------



## BasementBob




> Quote:
> Originally Posted by *Jrek* /forum/post/17386994
> 
> 
> corner bass traps ... I will eventually cover floor to ceiling but until I have enough traps for now do I place the panels on the floor straddling the corner or I have seen pictures of panels hung mid way between floor and ceiling which is the correct way to mount?



All modes are active in tri-corners. Start there.

(wall-wall is a corner. Wall-floor is a corner. Wall-ceiling is a corner.

Wall-wall-ceiling is a tri-corner. Wall-wall-floor is a tri-corner)


If you have measurement software, use that to find your most active/troublesome modes, and that will dictate more efficient placement, and alternative treatments.

i.e. test, hypothesize/diagnose, treat, repeat.



> Quote:
> Also should side wall first reflection panels be spaced away from the wall and if yes by how much?



That depends on other things (speaker-off-axis-response, speaker-wall-placement, envelopment/spaciousness, imaging at various frequencies, other reflections, other issues, over-absorption of high frequencies, etc etc etc). Nothing, or diffusion, are sometimes appropriate.

A rule of thumb is never more air behind a porous absorber than the thickness of the absorptive material.



In an otherwise empty/reflective room, studiotips superchunks and first reflection point absorbers are a good thing. In other rooms, your mileage will vary.


----------



## Weasel9992




> Quote:
> Originally Posted by *BasementBob* /forum/post/17390783
> 
> 
> All modes are active in tri-corners. Start there.



Yep...that'll work just fine. Giving panels a little bit of space will extend their low frequency response a little bit. Every little bit helps.


Frank


----------



## giomania

Here are pictures of my screen wall with the screen installed. I will cover it with GoM and it will be flanked by curtains on both sides.


I installed an extra 8" deep section of triangles in the upper-right corner of the front wall. The remain un-treated area there in the picture has the electrical panel and the structured wiring (low-voltage) box. I was wondering if I should cut a piece of 2" JM 814 to fit in there. It would have to be moveable for occasional access.


If you recall from my previous pictures, I did not have the lower 16" of the front wall treated. My solution is to lean the 2" panels in the bottom corner like you see in the picture behind the screen wall. That should be OK, right?


Thanks for any input.


Mark


----------



## Dennis Erskine

Congratulations to SierraMikeBravo ... he is now HAA Level II certified.


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17396871
> 
> 
> Here are pictures of my screen wall with the screen installed. I will cover it with GoM and it will be flanked by curtains on both sides.
> 
> 
> I installed an extra 8" deep section of triangles in the upper-right corner of the front wall. The remain un-treated area there in the picture has the electrical panel and the structured wiring (low-voltage) box. I was wondering if I should cut a piece of 2" JM 814 to fit in there. It would have to be moveable for occasional access.
> 
> 
> If you recall from my previous pictures, I did not have the lower 16" of the front wall treated. My solution is to lean the 2" panels in the bottom corner like you see in the picture behind the screen wall. That should be OK, right?



How does it sound? Any difference?


----------



## Jacob B




> Quote:
> Originally Posted by *giomania* /forum/post/17396871
> 
> 
> Here are pictures of my screen wall with the screen installed. I will cover it with GoM and it will be flanked by curtains on both sides.
> 
> 
> I installed an extra 8" deep section of triangles in the upper-right corner of the front wall. The remain un-treated area there in the picture has the electrical panel and the structured wiring (low-voltage) box. I was wondering if I should cut a piece of 2" JM 814 to fit in there. It would have to be moveable for occasional access.
> 
> 
> If you recall from my previous pictures, I did not have the lower 16" of the front wall treated. My solution is to lean the 2" panels in the bottom corner like you see in the picture behind the screen wall. That should be OK, right?
> 
> 
> Thanks for any input.
> 
> 
> Mark



Why did you prioritize wall-ceiling corner versus wall-floor corner? Just wondering, as I am planning my own treatment now.


Anyway, it looks great







Can't wait till I get to that point










Best,

Jacob


----------



## Jacob B

What are the pros and cons for a square vs. a triangle corner bass trap using the same amount of absorbing material?


I am considering doing a 1' x 1' square floor-wall bass trap (to leave room for the three tower speakers and the 19" x 28" SVS PB12-plus/2 sub behind the false wall - I win 5" of floor space this way) and I am wondering whether I should do the same for the ceiling-wall corner or make triangles...?? (planning on triangles in the tricorners)


1' x 1' is exactly the same amount of fiberglass material as a SCC trap measuring 17" x 17" x 24" (see attached drawing) - so what are the pros and cons?


I realize that for visible corners, tiangles are easier to make look nice / blend into the room. However, for treatment behind a false wall, that doesn't really matter. So I guess there is an acoustic reason for choosing triangles as well

















Cheers,

Jacob


----------



## CCDC

I just tore out the old wood panneling in our livingroom and am planning insulation and drywall, but before that goes in I was wondering if there were any recomendations for building in some sort of acoustic room treatment that would have high WAF.


ie flush with the drywall or built into the wall or corners of two walls.


Specific areas of interest include the covering (wood, vinyl, fabric) and how it would be attached and matched to the drywall when it is all in. The angled basstrap across the corner is not gonna fly so looking for other ideas that blend into the room a bit better so that I may avoid hearing the phrase "This is our livingroom, not a theater"


----------



## giomania




> Quote:
> Originally Posted by *pepar* /forum/post/17397435
> 
> 
> How does it sound? Any difference?



I don't know yet. Final speaker alignment / FRP absorber installation / Audyssey calibration to occur this weekend.


Mark


----------



## giomania




> Quote:
> Originally Posted by *Jacob B* /forum/post/17398198
> 
> 
> Why did you prioritize wall-ceiling corner versus wall-floor corner? Just wondering, as I am planning my own treatment now.
> 
> 
> Anyway, it looks great
> 
> 
> 
> 
> 
> 
> 
> Can't wait till I get to that point
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Best,
> 
> Jacob



Thanks for the compliment, Jacob.


I assume you mean why did I prefer the wall-ceiling corner for the Studiotips Super Chunks?


1) I have a lot of obstructions at the floor-ceiling area (electrical outlets, and wiring conduit / chase openings)


2) I wanted to have the flexibility to move the subs around behind the screen wall.


3) I was copying Pepar's project.










Mark


----------



## rec head




> Quote:
> Originally Posted by *CCDC* /forum/post/17399967
> 
> 
> I just tore out the old wood panneling in our livingroom and am planning insulation and drywall, but before that goes in I was wondering if there were any recomendations for building in some sort of acoustic room treatment that would have high WAF.
> 
> 
> ie flush with the drywall or built into the wall or corners of two walls.
> 
> 
> Specific areas of interest include the covering (wood, vinyl, fabric) and how it would be attached and matched to the drywall when it is all in. The angled basstrap across the corner is not gonna fly so looking for other ideas that blend into the room a bit better so that I may avoid hearing the phrase "This is our livingroom, not a theater"



Are you looking for sound proofing or just in-room acoustics?


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17400412
> 
> 
> I don't know yet. Final speaker alignment / FRP absorber installation / Audyssey calibration to occur this weekend.



A fellow local HT enthusiast installed a fair amount of SSC traps, but it wasn't until we re-did Audyssey that the full improvement in the sound became obvious.


----------



## CCDC




> Quote:
> Originally Posted by *rec head* /forum/post/17401145
> 
> 
> Are you looking for sound proofing or just in-room acoustics?



in room, acoustics. this is a first for me, but with the walls tore out, i figured now is the time to start.


Room dimensions are 14x21x9h with 'front' on the 14 wall. I had planned to 'treat' the entire front wall with some 703/705 or equivalent but need to find a way to cover that up if possible something seamless. Roof and floor are wood with only an area rug between front speakers and primary listening position.


if this is not the way to go then let me know. I am open to anything that can be concealed on sides and back. got more leeway on the front wall where all the TV & speaker stuff is anyway.


----------



## Jacob B




> Quote:
> Originally Posted by *giomania* /forum/post/17400451
> 
> 
> Thanks for the compliment, Jacob.
> 
> 
> I assume you mean why did I prefer the wall-ceiling corner for the Studiotips Super Chunks?
> 
> 
> 1) I have a lot of obstructions at the floor-ceiling area (electrical outlets, and wiring conduit / chase openings)
> 
> 
> 2) I wanted to have the flexibility to move the subs around behind the screen wall.
> 
> 
> 3) I was copying Pepar's project.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Mark



Makes sense.


Jacob


----------



## citizen arcane




> Quote:
> Originally Posted by *CCDC* /forum/post/17399967
> 
> 
> I just tore out the old wood panneling in our livingroom and am planning insulation and drywall, but before that goes in I was wondering if there were any recomendations for building in some sort of acoustic room treatment that would have high WAF.
> 
> 
> ie flush with the drywall or built into the wall or corners of two walls.
> 
> 
> Specific areas of interest include the covering (wood, vinyl, fabric) and how it would be attached and matched to the drywall when it is all in. The angled basstrap across the corner is not gonna fly so looking for other ideas that blend into the room a bit better so that I may avoid hearing the phrase "This is our livingroom, not a theater"



Look here:

http://www.avsforum.com/avs-vb/showthread.php?t=1047573


----------



## Jacob B




> Quote:
> Originally Posted by *CCDC* /forum/post/17403625
> 
> 
> in room, acoustics. this is a first for me, but with the walls tore out, i figured now is the time to start.
> 
> 
> Room dimensions are 14x21x9h with 'front' on the 14 wall. I had planned to 'treat' the entire front wall with some 703/705 or equivalent but need to find a way to cover that up if possible something seamless. Roof and floor are wood with only an area rug between front speakers and primary listening position.
> 
> 
> if this is not the way to go then let me know. I am open to anything that can be concealed on sides and back. got more leeway on the front wall where all the TV & speaker stuff is anyway.



If you can't have any visible seems, with cloth covered panels, maybe you can make the walls into Helmholz resonators. Google around (or wait for the xperts to show up ), but basicly it is a membrane (plywood, drywall etc) mounted with an air chamber behind with absorbing material like fiberglass. It is not a broadband absorber, but you might be able to construct it to absorb one or two of your room mode peaks (you can use the calculator here: http://www.realtraps.com/modecalc.htm to find frequency candidates). Based on your room dimensions and using modecalc, it looks like frequencies in multiples of 80.71 Hz are potential candidates.

BUT: You will likely need an acoustic expert to help you with the construction design of the Helmholz resonators.


You might be able to get away (WAF) with treating the whole front wall with, say 4-6" of OC703, with vertical wooden strips 1" x 4-6" every two feet and then cover it with some kind of tapestry / paper surface (using the wooden strips to fix the tapestry on). Again, consult with the experts, but this might give you some broadband bass absorption (but reflecting the mids and highs due to use of paper rather than AT cloth). I dont know whether you can make the tapestry look nice and smooth - I am just throwing stuff at ya










Good luck,

Jacob


----------



## CCDC

Appreciate it, that was exactly the kind of info i needed Jacob. I do plan to treat the front wall with some OC and covering that with some fabric stretched and tacked or just hang a theater style curtain over it .


A coworker when presented with my situation recommended stuffing the two voids between the studs on either side of a corner with the OC covering with fabric and then using slats of 5/8" wood to create a diffuser panel over the filling and that would bring the design flush with the 5/8" drywall on the studs next to it and could be painted to match the room.


----------



## giomania




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/14769253
> 
> 
> This would not be correct. Nylon, polyester, burlap or otherwise makes no difference. The differences between each fabric is not based upon the material...it is based upon the weave and weight.



Does anyone have a good source for curtains to use on the ends of my screen wall?


Thanks.


Mark


----------



## giomania

I have installed the FRP Absorption panels (1" JM 817) on the ceiling and the side walls for the front channel speakers. See the first three pictures.


In case you are wondering, the reason why there are two panels each on the side walls is because one controls reflections for the front row seating area, and one controls reflections for the back row seating area. The ceiling-mounted FRP absorbers only controls reflections for the front row seating area.


I have four FRP Absorption panels (1" JM 817) left, but was not planning to install those yet, as I am not certain of the advantages. However, if anyone has any sage advice based on the last picture of the rear part of my room. I also have some 2" JM 814 panels left that I can cut use to treat other areas of the rear of the room.


Today I will run Audyssey and tonight watch a movie.


Thanks for any input.


Mark


----------



## cuzed2




> Quote:
> Originally Posted by *giomania* /forum/post/17410529
> 
> 
> Does anyone have a good source for curtains to use on the ends of my screen wall?
> 
> 
> Thanks.
> 
> 
> Mark



We did the same thing:


We flanked the angled (bass-trapped) front corners with curtains. We found ours on sale at that famous French outfitter >> JC Penneee. Takes awhile; but with patience we found a great sale price.


If you dig into my thread you will see an example


----------



## giomania




> Quote:
> Originally Posted by *cuzed2* /forum/post/17410799
> 
> 
> We did the same thing:
> 
> 
> We flanked the angled (bass-trapped) front corners with curtains. We found ours on sale at that famous French outfitter >> JC Penneee. Takes awhile; but with patience we found a great sale price.
> 
> 
> If you dig into my thread you will see an example



Thanks,


Ideas always help; I found lots of pictures of your curtains. Did you have those tassles on the bottom sewn on, or did you find them like that at JC Pene'?


Thanks.


Mark


----------



## giomania

Well, the results are in:


First, I ran the SMS test tone on one of the Velodyne DD-15's just so I could see the graphed response from the main listening position, and it was pretty flat, within 3 dB, it appeared. I was using a little 7" LCD screen, but I looked really close. I know the response was not that flat before installation of the room treatments.


Next, I performed the Audyssey MULTEQ XT calibration (8 positions), and then watched / listened to the first couple chapters of Master & Commander Blu-ray. It has been awhile since I saw that clip, but I think I heard more subtle details, like more footsteps from above, etc. It definitely sounded more "crisp" and "bright", but not too bright.


I guess as time goes on, I may notice more details. I have two children (2 & 4), so do not have much time for critical listening these days.


Maybe tomorrow we can watch "Monsters vs. Aliens" in the theater.










Mark


----------



## johnbomb

Does anyone know at what Hz FRK begins to reflect frequencies?


John


----------



## giomania

Last night, my wife and I watched "The Soloist", which was the movie we had from Netflix. I had commented earlier in the evening that I was disappointed that was the first movie we had to watch since the installation of the acoustic treatments.


Well, I was pleasantly surprised, to say the least. Even though I have never seen this movie before, I noticed things in my setup that I do not recall experiencing prior to the acoustic treatments. For example: Increased dialogue intelligibility, more low-end subtleties, and better placement of sounds in the front soundstage.


Now, some people may call "BS" because I never saw the movie before, but it was just a sense that I had that everything was better. Even my wife commented that "Everything seemed more contained". Placebo? Perhaps, but ignorance is bliss, my friends. The water is fine...come on in!


Mark


----------



## Terry Montlick




> Quote:
> Originally Posted by *johnbomb* /forum/post/17414040
> 
> 
> Does anyone know at what Hz FRK begins to reflect frequencies?



It depends what is in back of it. But generally speaking, between 1 and 2 kHz.


- Terry


----------



## cuzed2

Mark,


We bought them that way.


BTW - we returned to JCP a few weeks ago looking for some shades for other windows, It appears they still have many choices; however > the curtains we bought for the HT room are no longer carried.


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17415200
> 
> 
> Last night, my wife and I watched "The Soloist", which was the movie we had from Netflix. I had commented earlier in the evening that I was disappointed that was the first movie we had to watch since the installation of the acoustic treatments.
> 
> 
> Well, I was pleasantly surprised, to say the least. Even though I have never seen this movie before, I noticed things in my setup that I do not recall experiencing prior to the acoustic treatments. For example: Increased dialogue intelligibility, more low-end subtleties, and better placement of sounds in the front soundstage.
> 
> 
> Now, some people may call "BS" because I never saw the movie before, but it was just a sense that I had that everything was better. Even my wife commented that "Everything seemed more contained". Placebo? Perhaps, but ignorance is bliss, my friends. The water is fine...come on in!



Mark, you describe the exact improvements that would be expected from installing the treatments that you did. I think it is very easy to listen to even unfamiliar content and notice the things you describe. Please post more when you've listened to _familiar_ content!


Jeff


----------



## thorr

I haven't taken the time to do all of my homework, but I wanted to ask some general questions. I am about to own a new house and I have a room that I will dedicate to my theater. It is rectangular with a closet in the back. The front wall is 95" tall by 145" wide. The side walls are 202" long. It is on the second floor of the house and the ceiling in the room goes up to a peak (because it is under the roof) in the center of the room at 133" high (horizonally when looking at the screen, not front to back). There is a huge window on the left side that I will have to deal with.


I want the room as dark as possible. I am planning on either covering all the walls and ceiling with black felt using push pins or possibly covering the walls and ceiling with something like this: http://www.foamexpress1.com/Acoustic_Sound.php For the window, I will probably get some heavy curtains and fasten the sides down so there is no light leakage.


My questions are, if I were to cover the room in acoustic foam, would it sound better or worse? Is it better to have a higher NRC, or would it make the sound too dead? In the future I could add base traps or whatever else, but I am mostly concerned about making the room dark and making the sound better while making it quieter for my neighbors. If I am better off with black felt for better overall sound quality at the expense of noise for the neighbors, I will go this way.


Thanks!

Mike


----------



## pepar

Just one alert: It is VERY easy to over-dampen the typical room in a residence.


----------



## thorr

So I am better off with just the felt then? Or perhaps just put the foam on the screen wall which is next to the neighbors?


Thanks,

Mike


----------



## kiwishred




> Quote:
> Originally Posted by *pepar* /forum/post/17416543
> 
> 
> Just one alert: It is VERY easy to over-dampen the typical room in a residence.



But, is overdampening actually a bad thing for sound clarity ? What are the effects of over-dampening on sound ?


The reason I ask is that song vocals and such always sound clearest to me listening through headphones. Presumably headphones = zero reverberation. Also, presumably any _desired_ room reverberation effects are already recorded into the sound track. Is it a good thing to allow the theatre room add additional, largely uncontrolled, reverberation ?


This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.


Brent


----------



## pepar




> Quote:
> Originally Posted by *thorr* /forum/post/17417249
> 
> 
> So I am better off with just the felt then? Or perhaps just put the foam on the screen wall which is next to the neighbors?
> 
> 
> Thanks,
> 
> Mike



I am not an acoustician, but I will say that I regret applying carpet up to (seated) ear level all around my room and am looking at installing diffusors.


----------



## pepar




> Quote:
> Originally Posted by *kiwishred* /forum/post/17417522
> 
> 
> But, is overdampening actually a bad thing for sound clarity ? What are the effects of over-dampening on sound ?
> 
> 
> The reason I ask is that song vocals and such always sound clearest to me listening through headphones. Presumably headphones = zero reverberation. Also, presumably any _desired_ room reverberation effects are already recorded into the sound track. Is it a good thing to allow the theatre room add additional, largely uncontrolled, reverberation ?
> 
> 
> This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.
> 
> 
> Brent



I hear ya. But I've been told by someone from THX that they shoot for a midband decay of 300ms. That is certainly something else entirely from "largely uncontrolled" reverberation. Mebbe the headphone experience doesn't scale up to a room?


----------



## pepar




> Quote:
> Originally Posted by *kiwishred* /forum/post/17417522
> 
> 
> 
> This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.



1) Right-sized absorbers at the first reflection points. Look around; there are more than most people think. (The one on my rear wall made the MOST difference in my room.)


2) SSC-style bass traps.


3) Measure. Listen. And go from there.


----------



## johnbomb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17415230
> 
> 
> It depends what is in back of it. But generally speaking, between 1 and 2 kHz.
> 
> 
> - Terry



Thanks, Terry.


John


----------



## bpape

Overdoing coverage, especially in something thin that only impacts high frequencies is not a good idea. The idea is to have a balanced scheme of absorption in the room.


As for target decay times, it depends purely on the usage of the room and the size of the room. A single number isn't adequate nor accurate for every room.


Bryan


----------



## giomania

I was wondering if there is any advice for FRP Absorber installation for surround and surround back speakers in a 7.1 setup? Ethan's article only covers a 5.1 setup with surrounds at 110-120 degrees. I have surround speakers located at 90 degrees and surround back speakers located at ~150 degrees.


For the surround speakers at 90 degrees, I would think there is no FRP absorber required, as they are pointed right at the listener?


For the surround back speakers, Ethan's formula can be used to calculate the placement of FRP absorbers on the side walls, correct?


Last, what is the recommendation for FRP absorbers on the rear wall? If I remember correctly, Toole's new book was discussing diffusion? I suspect this depends on a number of factors. My main lisenting position is about 15 feet from the rear wall.


Thanks for any input.


Mark


----------



## Ethan Winer




> Quote:
> Originally Posted by *giomania* /forum/post/17434650
> 
> 
> For the surround speakers at 90 degrees, I would think there is no FRP absorber required, as they are pointed right at the listener?



It depends on the width of the room. Better safe than sorry, especially if the room is less than 15 or 20 feet wide.



> Quote:
> what is the recommendation for FRP absorbers on the rear wall?



At 15 feet away you could add absorption or diffusion or neither. The "crossover" point is around ten feet away, where the reflections arrive sooner than about 20 milliseconds.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17434650
> 
> 
> I was wondering if there is any advice for FRP Absorber installation for surround and surround back speakers in a 7.1 setup? Ethan's article only covers a 5.1 setup with surrounds at 110-120 degrees. I have surround speakers located at 90 degrees and surround back speakers located at ~150 degrees.
> 
> 
> For the surround speakers at 90 degrees, I would think there is no FRP absorber required, as they are pointed right at the listener?
> 
> 
> For the surround back speakers, Ethan's formula can be used to calculate the placement of FRP absorbers on the side walls, correct?
> 
> 
> Last, what is the recommendation for FRP absorbers on the rear wall? If I remember correctly, Toole's new book was discussing diffusion? I suspect this depends on a number of factors. My main lisenting position is about 15 feet from the rear wall.
> 
> 
> Thanks for any input.
> 
> 
> Mark



Mark,


FWIW, I considered - and even made - absorbers for the rear surrounds (monopole) on the ceiling, but never installed them. The surrounds (side) are dipole and need reflections, imo, so no absorbers for them. I am 5'-6' from the rear wall. If I were 15', I would have installed diffusors.


----------



## LarryChanin




> Quote:
> Originally Posted by *kiwishred* /forum/post/17417522
> 
> 
> But, is overdampening actually a bad thing for sound clarity ? What are the effects of over-dampening on sound ?
> 
> 
> The reason I ask is that song vocals and such always sound clearest to me listening through headphones. Presumably headphones = zero reverberation. Also, presumably any _desired_ room reverberation effects are already recorded into the sound track. Is it a good thing to allow the theatre room add additional, largely uncontrolled, reverberation ?
> 
> 
> This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.
> 
> 
> Brent





> Quote:
> Originally Posted by *bpape* /forum/post/17433112
> 
> 
> Overdoing coverage, especially in something thin that only impacts high frequencies is not a good idea. The idea is to have a balanced scheme of absorption in the room.
> 
> 
> As for target decay times, it depends purely on the usage of the room and the size of the room. A single number isn't adequate nor accurate for every room.
> 
> 
> Bryan



Hi,


Here's a couple of oldies but goodies on the subject of "ideal" reverberation time.

RT60 what is a good value! 

what's the holy grail for rt60? 


Larry


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17396994
> 
> 
> Congratulations to SierraMikeBravo ... he is now HAA Level II certified.




Thanks Dennis! Could not have done it without your help and guidance!


----------



## LarryChanin




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17396994
> 
> 
> Congratulations to SierraMikeBravo ... he is now HAA Level II certified.





> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/17435569
> 
> 
> Thanks Dennis! Could not have done it without your help and guidance!



Hi Shawn,


Congratulations!!


Larry


----------



## giomania




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17435222
> 
> 
> It depends on the width of the room. Better safe than sorry, especially if the room is less than 15 or 20 feet wide.
> 
> 
> 
> 
> At 15 feet away you could add absorption or diffusion or neither. The "crossover" point is around ten feet away, where the reflections arrive sooner than about 20 milliseconds.
> 
> 
> --Ethan



Thanks for the responses, guys.


The room is 20 feet wide, so I am at the border. However, they are Mirage Omnipolar's, so I think the wall should be bare behind them. The one thing I am concerned about are the parallel surfaces. If you clap in the rear part of the room, it reverberates.


Any guidance on parallel surfaces?


Thanks.


Mark


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *LarryChanin* /forum/post/17436426
> 
> 
> Hi Shawn,
> 
> 
> Congratulations!!
> 
> 
> Larry



Thanks Larry!


----------



## lucifers_ghost

What if one was to take a standard movie poster and have it laminated. Then what if one took that laminated picture and installed it over an acoustic panel (say a GIK 242 panel).


Would that effect the functionality of the acoustic panel? Or would it not make a difference?


Just curious.


----------



## Terry Montlick




> Quote:
> Originally Posted by *lucifers_ghost* /forum/post/17437308
> 
> 
> What if one was to take a standard movie poster and have it laminated. Then what if one took that laminated picture and installed it over an acoustic panel (say a GIK 242 panel).
> 
> 
> Would that effect the functionality of the acoustic panel? Or would it not make a difference?
> 
> 
> Just curious.



It would make it reflect high frequencies, and potentially enhance the absorption of lows. Not good for early reflection treatment!


- Terry


----------



## lucifers_ghost




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17439149
> 
> 
> It would make it reflect high frequencies, and potentially enhance the absorption of lows. Not good for early reflection treatment!
> 
> 
> - Terry




Boooo! Thats what I was afraid of.


Just trying to think of some inventive ways to "dress up" the acoustic panels. While they are certainly not unsightly, they are rather .. meh .. bland I guess.


----------



## Terry Montlick




> Quote:
> Originally Posted by *lucifers_ghost* /forum/post/17439321
> 
> 
> Boooo! Thats what I was afraid of.
> 
> 
> Just trying to think of some inventive ways to "dress up" the acoustic panels. While they are certainly not unsightly, they are rather .. meh .. bland I guess.



Digital images can be custom printed on some acoustically transparent fabrics. If it is a dye process and the printing doesn't screw up the acoustical transparency, this is an excellent solution.


But beware of manufacturers claims, and ask for acoustical transparency test results. I came across one fabric printer/manufacturer advertising acoustically transparent fabric images. I asked for a sample, and tested it. The fabric was terrible, even before it was printed on! In this case, the manufacturer simply didn't know enough about acoustical testing. They used the NRC (Noise Reduction Coefficient) of acoustic panels made using the fabric, and this was indeed pretty good. But the NRC is the sound absorption average for major speech frequencies only. There is no testing for frequencies above the 2 kHz band.


When I brought this fact to the manufacturer's attention, they very responsibly withdrew the acoustical transparency claim.


- Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *giomania* /forum/post/17437265
> 
> 
> they are Mirage Omnipolar's, so I think the wall should be bare behind them.



I'm not familiar with that specific model, but generally, dipole speakers benefit from absorption on the front wall behind them. As I see it, when speakers radiate equally front and rear that's a _byproduct_ of the design, not a design goal. Untamed reflections give bass peaks and nulls, and also "smear" (though I hate that word) mids and highs.



> Quote:
> Any guidance on parallel surfaces?



Yes, you need either diffusion or absorption.










--Ethan


----------



## giomania




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17441994
> 
> 
> I'm not familiar with that specific model, but generally, dipole speakers benefit from absorption on the front wall behind them. As I see it, when speakers radiate equally front and rear that's a _byproduct_ of the design, not a design goal. Untamed reflections give bass peaks and nulls, and also "smear" (though I hate that word) mids and highs.
> 
> 
> 
> 
> Yes, you need either diffusion or absorption.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Thanks Ethan. I did cover my front wall, so am "covered" there. Regarding the placement of the diffusion or absorption on the parallel surfaces, is there any guidance on placement?


Mark


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17441994
> 
> 
> I'm not familiar with that specific model, but generally, dipole speakers benefit from absorption on the front wall behind them. As I see it, when speakers radiate equally front and rear that's a _byproduct_ of the design, not a design goal.



Really? Then how do the front and rear lobes create the diffuse soundfield and a sense of envelopment if they are absorbed?


----------



## Dennis Erskine

Omni polar designs came from a necessity to use the room as a surround processor for two-channel applications. They are not well suited for multi-channel applications in small rooms.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/17444277
> 
> 
> Really? Then how do the front and rear lobes create the diffuse soundfield and a sense of envelopment if they are absorbed?



There are different ways to do things of course. I know that we've specified diffusion behind a pair of dipoles with absorption between them (if space and set up permits).


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17446018
> 
> 
> There are different ways to do things of course. I know that we've specified diffusion behind a pair of dipoles with absorption between them (if space and set up permits).
> 
> 
> Frank



The diffusors behind the dipoles would serve to reflect more sound out into the room, right? The absorption in between is for what - general room treatment?


----------



## Ethan Winer




> Quote:
> Originally Posted by *giomania* /forum/post/17443536
> 
> 
> Regarding the placement of the diffusion or absorption on the parallel surfaces, is there any guidance on placement?



This depends on so many things I'd be writing for half a day to explain it all. It also depends on the size of the room and where the listener sits. Here are the high points:


* Diffusion is very common on the rear wall behind the listener.


* Diffusion can be used on the front wall behind dipole speakers if the listener prefers more ambience, but wants to avoid the small-room boxy sound often caused by leaving those early reflections untreated.


* IMO, diffusion is not useful at reflection points, but I've tried that only in my 16 foot wide living room. In much larger rooms diffusion there might be okay.


* Diffusion can be useful elsewhere on the side walls, especially if the room is small and you want to make it sound larger.


These two videos have further information and also let you hear what diffusors sound like:

All About Diffusion 
Hearing is Believing 


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17444277
> 
> 
> Really? Then how do the front and rear lobes create the diffuse soundfield and a sense of envelopment if they are absorbed?



My personal preference is for whatever "envelopment" that's embedded in the recording to come through unchanged. I don't want early reflections to cause comb filtering, which to my ears makes a room sound smaller, not larger. But that's me.










--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17447279
> 
> 
> My personal preference is for whatever "envelopment" that's embedded in the recording to come through unchanged. I don't want early reflections to cause comb filtering, which to my ears makes a room sound smaller, not larger. But that's me.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



I thought the context here was surround speakers and, IIRC, dipoles are used for surrounds because that's what Tom Holman determined was needed to recreate the sound of surround arrays in commercial cinemas. So, the goal as I understand it is not to recreate what is in the soundtrack, but to recreate how the soundtrack sounds in a commercial cinema.


If the context was dipole or omnipolar main speakers, then...nevermind.


----------



## johnbomb

Anyone ever heard of hemispherical diffusion? A (bad) example: mount a big wooden salad bowl on your wall. I wonder if a properly executed solution would be analagous to primitive root (skyline) diffusers, in that 2 dimensional diffusion is provided.


John


----------



## MikeWojcik

Was planning on using some rigid styrofoam behind my fabric walls where i do NOT want any absorption - just to keep the same 2" thickness.

Am using 2" OC703 at first relfection points and a few other reflection points.


Will the styrofoam be relatively equivalent to nothing there?


Thanks!


----------



## SoundProgression

If I have an area behind cloth that doesn't need treatment I leave it bare if the area is not subject to abuse. This is especially true if the cloth is very shear (acoustically transparent). If it's a heavy absortive cloth I'd either bring cheap sheetrock or MDF forward (light fiberglass between the sheetrock and exisiting wall) and keep the fabric very close to the sheetrock.


If you decide to use Styrofoam make sure you paint it because it's light color will telegraph through cloth.


----------



## SoundProgression

There are many companies that make spherical/hemispherical diffusers. The main problem compared to a Skyline is their efficiency and uniformity. Skylines scatter very well and that can be very important if the source or the receiver are close to the diffuser.


So, use a hemispherical diffuser but make sure they you give them a little extra distance to spread the sound, alter their size and you'll probably need to use a few more than you would skylines. You may want to use 2d diffusion and make the sound fan out more effectively in the direction needed than a poor 3d diffuser.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17447565
> 
> 
> dipoles are used for surrounds because that's what Tom Holman determined was needed to recreate the sound of surround arrays in commercial cinemas.



I'd have to see the context of that quote, but on the surface this seems very wrong. You can't "recreate the sound of surround arrays in commercial cinemas" in a small room unless you add artificial delays and reverb. A living room is just too small. And that shouldn't be needed anyway because many DVDs and Blu-rays claim to be re-mixed for home theaters.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17461485
> 
> 
> I'd have to see the context of that quote, but on the surface this seems very wrong. You can't "recreate the sound of surround arrays in commercial cinemas" in a small room unless you add artificial delays and reverb. A living room is just too small. And that shouldn't be needed anyway because many DVDs and Blu-rays claim to be re-mixed for home theaters.
> 
> 
> --Ethan



Perhaps they were the best simple way or they were better than monopoles as used in commercial cinemas, but I'll dig up the info.


----------



## rhcorolla

Follow-up to my post #5108: Utilizing 2” thk. OC703 w/ FRK foil face from a local insulation contractor, I treated my problematic/ severely compromised live/ hot room layout (wood floors w/ area rugs, painted wood panel walls, brick front wall, many openings) w/ (5) 2” thk. early reflection panels (FRK face @ back) & (2) 4” thk. 2’ x 4’ bass traps (FRK face @ front: both panels). I saw greatly improved results: tighter bass, more detail, far less echo.


After reading about the Studiotips Super Chunks (SSC) corner adsorbers, I decided to modify my (2) flat panel bass traps accordingly. My 17.5’ w x 11’ d x 8’ h den only has 1 true corner (back left behind recliners) where I located 24” w x 64” h solid diagonal super chunk to replace diagonal 4” panel & wall 4” panel directly opposite sub.


6.1 System: av123 ELT525 towers & center, Paradigm Cinema diopole surrounds & single surround back, Rythmik F12G subwoofer (sits on DIY subbdude located behind recliners in corner near diagonal trap); Denon avr-1909 w/ Audyssey speaker auto calibration but w/ Multi EQ set to OFF, Front/ sub xover: 80 Hz, Center 90 Hz, Surrounds 150 Hz, Surround back 110 Hz, Oppo BDP-83 Blu-ray player.


Utilizing RealTraps 10 Hz- 300 Hz test tones w/ Rat Shack SPL meter before/ after results are as follows (avr volume set @ 70 dB per track 30 pink noise) Seating/ mic position 3’ from back wall of 11’ room depth


10 Hz: corner super chunk: 64 dB, flat panels: 82 dB

20 Hz: corner super chunk: 76 dB, flat panels: 86 dB

30 Hz: corner super chunk: 81 dB, flat panels: 88 dB

40 Hz: corner super chunk: 81 dB, flat panels: 84 dB

50 Hz: corner super chunk: 82 dB, flat panels: 85 dB

60 Hz: corner super chunk: 84 dB, flat panels: 85 dB

70 Hz: corner super chunk: 78 dB, flat panels: 80 dB

80 Hz: corner super chunk: 84 dB, flat panels: 86 dB

90 Hz: corner super chunk: 83 dB, flat panels: 88 dB

100 Hz: corner super chunk: 90 dB, flat panels: 92 dB

110 Hz: corner super chunk: 89 dB, flat panels: 89 dB

120 Hz: corner super chunk: 83 dB, flat panels: 83 dB

130 Hz: corner super chunk: 86 dB, flat panels: 82 dB

140 Hz: corner super chunk: 78 dB, flat panels: 77 dB

150 Hz: corner super chunk: 74 dB, flat panel: 71 dB

160 Hz- 300 Hz: pretty much the same results for before/ after


While I haven’t tweaked sub location, etc.; I am encouraged w/ initial readings utilizing SSC corner trap. I did try dialing back sub volume an additional 4-5 dB, but overall sound was greatly diminished to my ears. I also prefer Audyssey MultiEQ On vs. Off audio-wise (boosts 10- 80 Hz sub readings on avg. by 5 dB).


I realize any given room can vary & YMMV, but thought a comparison of the 2 bass treatments would be interesting for those considering SSC or 4" bass traps.


Any thoughts/ comments on these results are most welcome.


----------



## pepar




> Quote:
> Originally Posted by *rhcorolla* /forum/post/17462484
> 
> 
> 
> Any thoughts/ comments on these results are most welcome.



Not that you can - or would want to - but your room has corners where the walls meet the ceiling and the floor. The former might be a location to consider if you want to add more traps.


Just throwing that out there . . .


Jeff


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17461485
> 
> 
> I'd have to see the context of that quote, but on the surface this seems very wrong. You can't "recreate the sound of surround arrays in commercial cinemas" in a small room unless you add artificial delays and reverb. A living room is just too small. And that shouldn't be needed anyway because many DVDs and Blu-rays claim to be re-mixed for home theaters.
> 
> 
> --Ethan



' Ere ya go !


----------



## Ethan Winer

That's an interesting article, but I'm not sure how relevant it is today where DVD mixes are done specifically for HT. His tests sound interesting, but I didn't see a room size for either test described. This makes all the difference in the world. Regardless, I'm not a fan of dipole speakers generally, so maybe I'm biased.


--Ethan


----------



## MikeWojcik

Have read in numerous places that it is better to locate the subwoofer as close to the floor as possible. I will be installing the subwoofer inwall at the bottom of the screen wall. Recently decided to add a small stage about 6-8" high.

Will fill it with sand per many plans / recommendations I've read. Will this reduce the performance of my sub?


Thanks

Mike


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17467648
> 
> 
> That's an interesting article, but I'm not sure how relevant it is today where DVD mixes are done specifically for HT. His tests sound interesting, but I didn't see a room size for either test described. This makes all the difference in the world. Regardless, I'm not a fan of dipole speakers generally, so maybe I'm biased.
> 
> 
> --Ethan



I know that some movies are remixed for the home market, but not all are. (Maybe even not that many?) But even with a home mix, do you think that they are doing any more than readjusting levels which still does nothing to create the diffuse field of a surround array in a commercial cinema?


Do you mainly listen to music?


Jeff


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/17468046
> 
> 
> I know that some movies are remixed for the home market, but not all are. (Maybe even not that many?) But even with a home mix, do you think that they are doing any more than readjusting levels which still does nothing to create the diffuse field of a surround array in a commercial cinema?



Very few are remixed. Noteably those from Disney and New Line (RIP). The vast majority are not remixed, but are cleaned up wrt edit gaps, clicks, or other such flaws that were not noticed on the dubbing stage, and the EQ is tweaked if needed.


----------



## pepar




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/17468303
> 
> 
> Very few are remixed. Noteably those from Disney and New Line (RIP). The vast majority are not remixed, but are cleaned up wrt edit gaps, clicks, or other such flaws that were not noticed on the dubbing stage, and the EQ is tweaked if needed.



Roger, what is your thinking on dipole vs monopole surrounds for movies wrt Tom Holman's earlier research?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17467771
> 
> 
> Have read in numerous places that it is better to locate the subwoofer as close to the floor as possible.



Where? It is usually on the floor because it is small and heavy and people do not want to see it, if possible. That, unfortunately, assures that it will maximally excite at least one room mode and, if close to other boundaries, possible more. This give maximal output but the most nonlinear output.


ASC makes a trap ( http://www.acousticsciences.com/subtrap.pdf ) which raises the sub off the floor to prevent this.


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/17468404
> 
> 
> Roger, what is your thinking on dipole vs monopole surrounds for movies wrt Tom Holman's earlier research?



Tom's stated goal was to try to replicate the theatrical experience, circa 1989, when that was dominated by Dolby Stereo, a.k.a Pro Logic, a single U-shaped mono array spanning the side and back walls of the theater. Diffuse rears was the order of the day. THX's dipoles attempted to recreate that same feeling, and it does work reasonably well.


Yamaha had their own approach with Theater DSP. They came to Dolby around that same time and, since they had been developing their DSP concert hall processing for several years prior, were not keen to toss it out and adopt THX as were their various competitors. Rather, they made new DSP modes to mimick theater acoustics. They brought an early unit to Dolby and set it up in our theater to show us how well they succeeded. Our theater experts acknowledged they succeeded, only too well, and reproduced some of the things that happen in theaters with undesirable acoustics--too much reverb mainly. Of course that is an adjustable parameter on the Yamaha products, but too much of a "good thing" turned out not to be on that day.


Getting reverb down in a huge space is no easy task, nor is it inexpensive, but it is desirable in order to improve clarity and detail. If the mixers want to create the sensation of hiding in a clothes closet--it's not easy when the room overlays a long reverb tail. If they want to create a pinpoint sound to the left of the audience, it's not easy when it comes out 6 speakers spanning 50 feet.


While of course there were some 70mm movies with split surrounds long before digital audio arrived on film, it wasn't until the overall theater industry moved to 5.1 discrete that more attention was drawn to the ability to create spot effects in theaters--taking full advantage of the technology. Then EX added one more degree of freedom to directional control. If you look at the SMPTE Digital Cinema specs, there are some 20+ channels identified in an attempt to future proof the path forward, and it includes not only the current Ls/Rs,Cs surround arrays, but discrete speakers in the rear corners for even more precisely focused spot effects.


In other words, one could say that the trend is toward better directional control, and in that sense, theaters are trying to catch up with the capabilities of smaller rooms (home theaters).


My thinking is that theaters suffer certain compromises in order to uniformly cover 200-300 wall-to-wall seats with sound, and we need not faithfully mimic those, nor the sticky floors, when we design home theaters. Let home theaters do what they do best. Clean sound, low reverb, presentation of pinpoint directionality and immersive spatial diffusion (as dictated by the mix, not the acoustics), for movies and music. _Vive la différence._


----------



## pepar




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/17469107
> 
> 
> 
> In other words, one could say that the trend is toward better directional control, and in that sense, theaters are trying to catch up with the capabilities of smaller rooms (home theaters).



I thought that we had gone beyond the commercial cinema experience, and it make sense that they would try to outdo the home theater experience like they did with early television and 'Scoped movies.


So bipoles for home theater surrounds?


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/17469236
> 
> 
> I thought that we had gone beyond the commercial cinema experience, and it make sense that they would try to outdo the home theater experience like they did with early television and 'Scoped movies.



Yes, I'm saying that commercial theaters are the ones trying to catch up.


I think in certain respects Commercial theaters have always exceeded the capabilities of home theatres, and always will--the sense of an event shared by a hundreds of people. If they'd only stop texting...



> Quote:
> So bipoles for home theater surrounds?



Absolutely. They are a good tool. Wide, smooth dispersion. One of Floyd's faves, too. Can't argue with that.


----------



## giomania




> Quote:
> Originally Posted by *pepar* /forum/post/17469236
> 
> 
> So bipoles for home theater surrounds?





> Quote:
> Originally Posted by *Roger Dressler* /forum/post/17469469
> 
> 
> Absolutely. They are a good tool. Wide, smooth dispersion. One of Floyd's faves, too. Can't argue with that.



Whoo-Hoo! Finally, I have the right type of speaker in the right place: Mirage Omnipolar (OM-5, OM-7) in the surround and surround back positions.


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17470823
> 
> 
> Whoo-Hoo! Finally, I have the right type of speaker in the right place: Mirage Omnipolar (OM-5, OM-7) in the surround and surround back positions.
> 
> 
> Mark



Adjustable radiation pattern? Omnipolar is not the same as bipolar.


----------



## giomania




> Quote:
> Originally Posted by *pepar* /forum/post/17470845
> 
> 
> Adjustable radiation pattern? Omnipolar is not the same as bipolar.



They radiate front and back, in phase, at the same time.


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania* /forum/post/17470857
> 
> 
> They radiate front and back, in phase, at the same time.
> 
> 
> Mark



Yep, that's bipole. "Omnipolar" must be part of the product name.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17468046
> 
> 
> I know that some movies are remixed for the home market, but not all are.



I have a bunch that claim to be special HT mixes, but I have no idea how many DVDs do that. If others here say it's rare, I have no reason to doubt that.



> Quote:
> Do you mainly listen to music?



In my living room HT my wife and I watch regular and HD Television, DVD and Blu-ray movies, and we listen to music. Of course, a lot of movies have music!










--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17454509
> 
> 
> Was planning on using some rigid styrofoam behind my fabric walls where i do NOT want any absorption - just to keep the same 2" thickness.



That should be fine. Styrofoam is mostly "inert" for acoustics.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17462556
> 
> 
> ' Ere ya go !



I'll look later and comment when I can. I admit I don't have a lot of experience with dipoles, mostly because the few times I heard them I wasn't impressed. But that doesn't mean they're never useful.


--Ethan


----------



## maxfli

Hi all,


I have been reading this forum for some time and have now decided to begin treating my room. My room is a converted 2-car garage designed more for visual appeal than acoustics. As you'll see it has several design features that may or may not help with acoustics, so I'm not certain as to what and how many treatment panels the room will need.


This is my first attempt at posting images, so I hope this goes as planned.

Attachment 157209 


The projector screen sets on a false wall which is 10" from the back wall. The plasmas on the left and right are on levers that allow them to be moved behind the false wall when just watching the projector screen. This results in a pocket between the back wall and the false wall per the next image.

Attachment 157210 


In the next attachment, you can see the tray ceiling and pillars on the side wall that were added for visual appeal.

Attachment 157211 


The left side wall has arched pillars around the wet bar and door to a storage closet. The room entry is on the far left side of the above image.

Attachment 157222 


The right wall has similar arched pillars with a bay window of sorts.

Attachment 157227


----------



## maxfli

Continued - the back wall has no pillars or shapes like the side and front walls, just 2 rear channel speakers.

Attachment 157239 


So, the room has several arches, a tray ceiling, coveys for wetbar and bay window plus curtains on the walls and carpet that influence the sound in the room, which right now is pretty good.


I am expecting to add some 2' x 4' bass traps on the back wall under the plasma screens, a bass trap on the rear wall between the rear surround speakers, and maybe some traps in the tray ceiling. I also may add a trap or two inside the arched areas as it makes sense.


But I'm trying to maintain the design of the room without adding any eye sores for treatments. Any thoughts or ideas would be appreciated.


thanks,

Max


----------



## Weasel9992




> Quote:
> Originally Posted by *maxfli* /forum/post/17477295
> 
> 
> I am expecting to add some 2' x 4' bass traps on the back wall under the plasma screens, a bass trap on the rear wall between the rear surround speakers, and maybe some traps in the tray ceiling. I also may add a trap or two inside the arched areas as it makes sense.



That sounds like a good plan. You can just see where you are after that and add more if you need to.


Frank


----------



## johnbomb

I've read that FRK is flammable. Does anyone know of a non flammable FRK alternative- one with similar acousitcal properties? Preferably something that reflects frequencies above 1k hz. This may sound silly, but how would tinfoil or thin plastic do (don't worry, I'd cover it w/ fabric







)


Thanks,

John


----------



## pepar




> Quote:
> Originally Posted by *johnbomb* /forum/post/17508499
> 
> 
> I've read that FRK is flammable. Does anyone know of a non flammable FRK alternative- one with similar acousitcal properties? Preferably something that reflects frequencies above 1k hz. This may sound silly, but how would tinfoil or thin plastic do (don't worry, *I'd cover it w/ fabric*
> 
> 
> 
> 
> 
> 
> 
> )



Non-flammable?


----------



## johnbomb




> Quote:
> Originally Posted by *pepar* /forum/post/17509321
> 
> 
> Non-flammable?



Woops! Plastic, not so much (that was an afterthought). I had GOM in mind for fabric- supposed to be non flammable.


----------



## bmwnbnw

hello guys, im new here but can someone provide some insight on treatment for my humble stereo room?

avsforum.com/avs-vb/showthread.php?t=1195503 


thank you


----------



## stgdz

Doing a search for green glue I came upon this thread
http://www.gearslutz.com/board/1480199-post21.html 


So has anyone attempted this blocking technique?


----------



## KERMIE

I don't know what I am talking about but I always understood things need to be able to flex a little- that blocking looks like it won't allow that.


----------



## Bill Mac

I just started looking at room treatments for my HT/Audio/Livingroom. The GIK 242 panels and the Tri-traps look like they will blend in my room if that is possible







. My room is 13' deep by 17' wide which is open on one side to a woodstove hearth/staircase with 8' ceilings. Basically a acoustical nightmare but it is what it is







. I am able to place my LCR (Ascend Sierra-1s) fairly well about 6' apart and my seat is dead center about 8' away. I feel I have a decent system but from what I have read treating my room might improve overall SQ quite a bit.


I am curious at the quality of GIK panels or is the DIY alternative a good choice to save on the cost for an entire room? I saw a post with a link to a company that sold various foam panels as well as cloth but can not recall the name of the company. Are there many companies out there that cater to DIYs for room treatment products? Any advice or thoughts would be appreciated







.


Bill


----------



## yacht422




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/17468684
> 
> 
> Where? It is usually on the floor because it is small and heavy and people do not want to see it, if possible. That, unfortunately, assures that it will maximally excite at least one room mode and, if close to other boundaries, possible more. This give maximal output but the most nonlinear output.
> 
> 
> ASC makes a trap ( http://www.acousticsciences.com/subtrap.pdf ) which raises the sub off the floor to prevent this.



walt here:

this is an expensive unit. how great an effect will it have on the sound? i have a 16' x22' x10' room, two subs on a concrete floor. anyone have real life experience with the concept?

thx

walt


----------



## yacht422

walt again, new question(s).

same 16x22x10 room, concrete floor, carpeted.(man cave!)

1) ihave o/c 703 at 1st and second reflection points, all facings removed, prox 4' X 6'. covered in guliford with wood frames(all diy) the ? is, are these the correct size???

2) said panels rest against the walls. I am considering "framing" the rear of the panels with additional 703 which allows an additional 1.75" behind the panels, but, with open space inside of the "framing". is there any advantage to doing so?

3) i built corner traps (ala super chunk concept i think it is called) - - - floor to ceiling - - - the ?? is, what should they be faced with? since this is a bass control concept, do i face with guilford, or 1/4" plywood, or or pegboard, or diffusion?(additional info - - we have 8 leather recliners, the outermost seats are located 6" from the rear wall, and prox 2.5' from the corners traps)

4) putting a sub on a stand. there are commercial units out there, but, is seems to border on smoke and more smoke to me. so - do they really offer sonic benefits?

finally, the room has a trey ceiling. the plate height is 9' with the trey gaining an additional 12" for a total of 10'. any recommendations as to the need to treat, and if so, how.

many, many thanks for insights about to be gained!!

walt


----------



## Kal Rubinson




> Quote:
> Originally Posted by *yacht422* /forum/post/17533117
> 
> 
> walt here:
> 
> this is an expensive unit. how great an effect will it have on the sound? i have a 16' x22' x10' room, two subs on a concrete floor. anyone have real life experience with the concept?
> 
> thx
> 
> walt



I was not really suggesting that you buy it, only that you read what they have to say for ideas. My experience with it is here: http://www.stereophile.com/musicinth...ic/index1.html


----------



## yacht422




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/17533867
> 
> 
> I was not really suggesting that you buy it, only that you read what they have to say for ideas. My experience with it is here: http://www.stereophile.com/musicinth...ic/index1.html



thx for the insights. i'll look into "the box" on monday.

Taming the mighty bass beast is a task







- especially in a multi-chair movies dedicated room. _[i have read books on how to tune a room (jim smith comes to mind -there are others) and they devote 90% of their teachings to a single chair in a small room - the writings did me next to no good at all in room dedicated to movies (and dvd classical music).]_
_the quest continues_









again, my thanks

walt


----------



## SoundProgression




> Quote:
> Originally Posted by *stgdz* /forum/post/17528667
> 
> 
> Doing a search for green glue I came upon this thread
> http://www.gearslutz.com/board/1480199-post21.html
> 
> 
> So has anyone attempted this blocking technique?



I haven't used this technique exactly. I do use blocking very near the ceiling lid to help with flanking noise that may make it into the wall cavity not going vertically into the joist or floor above.


I'd never use the one shown for noise isolation when there are others about as simple but much more effective. Adding extra blocking (looks like fire-blocking) makes the wall more stiff and adds coupling points for the two sides of the wall and should make it sound transmission worse.


Leaving the cavities alone and adding unfaced fiberglass and carefully sealing the perimeter framing, the GWB and other openings with acoustical caulking would be better.


There are several better ways to improve a simple wall. One way is making the studs staggered (not as simple)(1" offset is fine) and make the studs 16"-24" O.C. Use fiberglass or similar in the cavities. Then you'd have a decoupled wall, it's cavity depth is greater (thicker is better).


----------



## SoundProgression




> Quote:
> Originally Posted by *yacht422* /forum/post/17533117
> 
> 
> walt here:
> 
> this is an expensive unit. how great an effect will it have on the sound? i have a 16' x22' x10' room, two subs on a concrete floor. anyone have real life experience with the concept?
> 
> thx
> 
> walt



I put multiple subs in most room designs. Concrete floors are usually not the issue. The construction of the rest of the room is.


Multiple subs can improve low frequency performance significantly. However, you need to put them in the right places. And, you need to be sitting on the right place.


ASC Sub-Traps work great and I recommend them if: you need to decouple a vibrating sub from an upstairs room so it doesn't vibrate the floor below and annoy people below or the sub (subs) can't be located where they should be and you need to "soften" the subs output (meaning remove from a boundary) a little to help improve (flatten) low frequency response (seems to help above the first order modes).


If possible put the subs where they can be and try the ASC Sub-trap to see if it works in your case.


----------



## yacht422




> Quote:
> Originally Posted by *SoundProgression* /forum/post/17539163
> 
> 
> I put multiple subs in most room designs. Concrete floors are usually not the issue. The construction of the rest of the room is.
> 
> 
> Multiple subs can improve low frequency performance significantly. However, you need to put them in the right places. And, you need to be sitting on the right place.
> 
> 
> ASC Sub-Traps work great and I recommend them if: you need to decouple a vibrating sub from an upstairs room so it doesn't vibrate the floor below and annoy people below or the sub (subs) can't be located where they should be and you need to "soften" the subs output (meaning remove from a boundary) a little to help improve (flatten) low frequency response (seems to help above the first order modes).
> 
> 
> If possible put the subs where they can be and try the ASC Sub-trap to see if it works in your case.



thank you for your response - my h/t is a self contained man cave. totally isolated from everyone/everywhere. that said, i have total location options as the room is dedicated to movies / classical music and there are no wife factors to deal with.

kal seems to like the units, and you are offering conditions where they would be of most assistance: none of those conditions exist for me.

so - - - is the elevation of the sub the trick







, or is it the construction of the box itself that does the trick? this may be unanswerable except by mr noxon himself, and he has a product to sell.

gents: any additional insight you can offer me? i can build a box with a ported tube inside of it (with insulation) which seems to be the heart of the asc unit - - -or, as usual, am i missing something?

thanks

walt


----------



## SoundProgression




> Quote:
> Originally Posted by *yacht422* /forum/post/17539377
> 
> 
> thank you for your response - my h/t is a self contained man cave. totally isolated from everyone/everywhere. that said, i have total location options as the room is dedicated to movies / classical music and there are no wife factors to deal with.
> 
> kal seems to like the units, and you are offering conditions where they would be of most assistance: none of those conditions exist for me.
> 
> so - - - is the elevation of the sub the trick
> 
> 
> 
> 
> 
> 
> 
> , or is it the construction of the box itself that does the trick? this may be unanswerable except by mr noxon himself, and he has a product to sell.
> 
> gents: any additional insight you can offer me? i can build a box with a ported tube inside of it (with insulation) which seems to be the heart of the asc unit - - -or, as usual, am i missing something?
> 
> thanks
> 
> walt



Most guys would envy your situation. Yes, there are lots of ways to make something similar. Art's box is very similar to a short fat Super Tubetrap. But is this the solution you need?


Your right. Getting the sub off the floor is part of it then absorbing some bass is another.


Multiple sub-woofer position, setup, and acoustical and electronic correction is a great subject. I hope others join in. Maybe I should I start another thread?


I'd like to make sure the product you're looking at is actually the solution to the problem. May I ask a few questions so I know where you're at. Let me know if I'm going in the wrong direction.


1) Are you having problems with your subs now and if so can you describe what you hear?

2) Have you experimented with different positions for your seating and sub positions?

3) Have you tried using an SPL meter and graphed the frequency response where you currently sit and with the speakers are? Often we guess at the problem and sometimes there may be two or more convoluted issues that confuses our ears that only looking at a measurement can sort out.

4) How is the rest of the room constructed: sheetrock, wood paneling, lots of doors, windows, symmetrical seating (a sketch usually works, send me one)?

5) How do you set up your processor for your front speakers and subs.


Let me know if can help.


----------



## jvvjvv

Want to thank those you helped me get this far. I have decoupled the ceiling and double SR/GG the room and a few other things I would not have done, save this forum.


The room is 8'W x 17'L x 7'H.......(no choice in the dimensions as to basement lay out).


I have a 60 in monitor on the way with floor speakers about 38" tall and the center speaker will be 38" off the floor. This will pretty much match ear height in the listening area.


If I build DVD storage shelves on both side walls, how will this impact reflection? Or, if I place the shelves above the 4' area and add absorbers from the shelf bottom to the floor. Also does this create another "corner" under the shelf, that has to be treated with a base trap?


Thanks, Jack


----------



## pepar




> Quote:
> Originally Posted by *jvvjvv* /forum/post/17542131
> 
> 
> Want to thank those you helped me get this far. I have decoupled the ceiling and double SR/GG the room and a few other things I would not have done, save this forum.
> 
> 
> The room is 8'W x 17'L x 7'H.......(no choice in the dimensions as to basement lay out).
> 
> 
> I have a 60 in monitor on the way with floor speakers about 38" tall and the center speaker will be 38" off the floor. This will pretty much match ear height in the listening area.
> 
> 
> If I build DVD storage shelves on both side walls, how will this impact reflection? Or, if I place the shelves above the 4' area and add absorbers from the shelf bottom to the floor. Also does this create another "corner" under the shelf, that has to be treated with a base trap?



Bass traps can help everywhere, but bass is "more concentrated" in corners and traps are usually more effective there depending on the problems to begin with.


----------



## SoundProgression




> Quote:
> Originally Posted by *jvvjvv* /forum/post/17542131
> 
> 
> Want to thank those you helped me get this far. I have decoupled the ceiling and double SR/GG the room and a few other things I would not have done, save this forum.
> 
> 
> The room is 8'W x 17'L x 7'H.......(no choice in the dimensions as to basement lay out).
> 
> 
> I have a 60 in monitor on the way with floor speakers about 38" tall and the center speaker will be 38" off the floor. This will pretty much match ear height in the listening area.
> 
> 
> If I build DVD storage shelves on both side walls, how will this impact reflection? Or, if I place the shelves above the 4' area and add absorbers from the shelf bottom to the floor. Also does this create another "corner" under the shelf, that has to be treated with a base trap?
> 
> 
> Thanks, Jack



I'd break the problem into two parts, those above about 100Hz and those below 100Hz. Modes don't start getting smoothed out until about 150Hz (more evenly spaced and dense).


The good news is small rooms generally have shorter decay times than large rooms (less need for general absorption) and the bad news is room modes (hard to treat) and first reflections (need effective spot absorptive treatment) can be severe.


Below 100Hz


Your modes are very widely spaced below 150Hz. They're hard to treat acoustically. The problem is usually not just the peaks but the extreme difference in the amplitude of the peaks that are right next to a null. Basstraps might help a some. You'd need to target your strong length modes first. Upper frequency basstraps (100Hz to maybe 250Hz) would be more useful. Corners are the usually the best choice as another person already mentioned.


You have modes at 33Hz (1st order length), 66Hz (second order length) and 70-80Hz (1st order width and height).


I've put a downloadable chart here, www.soundprogression.com/Download/SPCalc.pdf , showing peaks and nulls for your room (doesn't show expected levels of the peaks and nulls) to help you choose where to sit (where modes cross or meet). At least you'll get an idea of the issues.


You're an ideal candidate for two subs, one in the back center and the other in the front center (see page 75-76 of http://www.harman.com/EN-US/OurCompa...s/multsubs.pdf ). It's works very well eliminating or at least reducing peaks and nulls.


Equalization would be a big help too.


Above 100Hz


I'd spot treat the first reflection points with a minimum of 2" fiberglass. I usually increase that area by 18" or more so often the treament spot is 3-4' x 3'x4'. I also like to use small ASC TubeTraps that can be moved along the reflection path and are free standing. Include the rear wall, sidewall and the ceiling (if possible). Your DVD storage might work but you'd need to purposefully avoid making the DVD's evenly spaced and stack right next to each other(leave holes in rows). Basically, you need to provide spacing so sound will go into an opening but not come out or be "broken up" or diffused so you don't get a strong reflection.


----------



## highcap

Hope this is the correct thread for this question. Does anyone know of a wholesale/retail location in or near St. Louis, MO that sells OC703 or Roxul/Lineacoustic equivalents? ATS has great pricing, but the shipping costs would kill me.


I'll need about 90 2x4 sheets of OC703 to do all my walls.


----------



## pepar




> Quote:
> Originally Posted by *highcap* /forum/post/17543315
> 
> 
> Hope this is the correct thread for this question. Does anyone know of a wholesale/retail location in or near St. Louis, MO that sells OC703 or Roxul/Lineacoustic equivalents? ATS has great pricing, but the shipping costs would kill me.
> 
> 
> I'll need about 90 2x4 sheets of OC703 to do all my walls.



Look in the yellow pages for an HVAC insulation distributor. SPI , the company I always link people to, doesn't seem to have a branch close to you.


Jeff


----------



## audhunt

Does anybody here know anythig about ownes corning SOFTR® All Service Fiber Glass Duct Wrap? It is the only duct wrap i can find in houston Texas. It has a backing on it and its 1 1/2 inches thick. Can this be used on the walls and screen wall?


----------



## audhunt

ok...just came across another type, Knauf Friendly Feel Duct Wrap. Again this is 1 1/2 inches thick and is faced. What to do? I would love some advice on the two options.


Thanks


----------



## pepar

Bob Gold's Absorption Coefficient List is your friend.


----------



## yacht422




> Quote:
> Originally Posted by *SoundProgression* /forum/post/17539903
> 
> 
> Most guys would envy your situation. Yes, there are lots of ways to make something similar. Art's box is very similar to a short fat Super Tubetrap. But is this the solution you need?
> 
> 
> Your right. Getting the sub off the floor is part of it then absorbing some bass is another.
> 
> 
> Multiple sub-woofer position, setup, and acoustical and electronic correction is a great subject. I hope others join in. Maybe I should I start another thread?
> 
> 
> I'd like to make sure the product you're looking at is actually the solution to the problem. May I ask a few questions so I know where you're at. Let me know if I'm going in the wrong direction.
> 
> 
> 1) Are you having problems with your subs now and if so can you describe what you hear?
> 
> 2) Have you experimented with different positions for your seating and sub positions?
> 
> 3) Have you tried using an SPL meter and graphed the frequency response where you currently sit and with the speakers are? Often we guess at the problem and sometimes there may be two or more convoluted issues that confuses our ears that only looking at a measurement can sort out.
> 
> 4) How is the rest of the room constructed: sheetrock, wood paneling, lots of doors, windows, symmetrical seating (a sketch usually works, send me one)?
> 
> 5) How do you set up your processor for your front speakers and subs.
> 
> 
> Let me know if can help.



1) bass was somewhat loose, but, with the addition of the corner traps, (newly installed) things have improved. do not know how much better it really can be - not certain how to determine such a thing!

2) seating (8 leather recliners) are fixed in place. subs can( and have been) _moved about._

3) the short answer is no. the longer answer is i use the anthem room correction (ARC) software, which is similar to the audussey (sp) system, but i am told, better. my processor is the anthem D-2 unit, with the anthem P5 amp. all feeding revel ultima II l/c/r and surround spkrs. ACR smoothes things out, provided the basic room issues are not past +/- 6DB from a 75 DB baseline. using the above i am provided a chart(post measurements) graphing what ARC found and corrected. My issue to date is a -7DB drop in the surrounds in the 1000 to 2000 range, and a room hump at the 20hz to 70 hz range in the mains(which included the subs) which exceeds +7DB. also, the sub profile is not smooth, but, rather, is bimodal.

none of this is extremely troublesome, but i am looking to improve. (are not we all?)









4) the room is concrete block on concrete floor with rigid f/g glued to the block, then wood 2X4 with pink insulation, then 1/2" drywall. there is one door, and one double wide window, located in the rear of the room, covered with velvet drapes. there are other sound containment things that i did to ensure that the neighbors would not be offended by Mahlers' 2nd at 2am!









5) answered above. Anthem D-2 processor + ARC.

the sub box is really an afterthought to my primary concern, which is what to do about the existing reflection point(s) wall units. [posted just prior to the sub post.

walt


----------



## Dennis Erskine

Actually, you'll find the transition to phase based (modal) problems will occur between 500 and 300 Hz depending upon the room. Generally (not always) it is the first three axial modes that will cause the most audible problems. That is not to say other modes will not be problematic. If you have an RTA, the first thing to do is measure response in a right tri-corner of the room to determine exactly what your modal frequencies are. The second is to do a near field measurement of your speakers (you don't want to be fixing speaker problems with acoustical treatments).


----------



## SoundProgression




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17545298
> 
> 
> Actually, you'll find the transition to phase based (modal) problems will occur between 500 and 300 Hz depending upon the room. Generally (not always) it is the first three axial modes that will cause the most audible problems. That is not to say other modes will not be problematic. If you have an RTA, the first thing to do is measure response in a right tri-corner of the room to determine exactly what your modal frequencies are. The second is to do a near field measurement of your speakers (you don't want to be fixing speaker problems with acoustical treatments).



Absolutely couldn't agree more. Thank you for adding that.


----------



## Fire Man

Looking for feedback on panel placements. This is my set up...











Panels are in red.


The entry and the window on the sides will have curtains, hoping those double as panels. My biggest question is to the right of the front left speaker. I'd prefer to put a flat panel on the wall starting at the corner. In the diagram I have a triangle panel simply to match the other corner.


If anyone could offer an insight on what might work for me I'd appreciate it.


----------



## audhunt




> Quote:
> Originally Posted by *pepar* /forum/post/17544336
> 
> 
> Bob Gold's Absorption Coefficient List is your friend.



That's all greek to me. Anyone else have some input on the two types?


----------



## pepar




> Quote:
> Originally Posted by *Fire Man* /forum/post/17545516
> 
> 
> 
> If anyone could offer an insight on what might work for me I'd appreciate it.



What software did you use to generate the room graphic?


----------



## Fire Man




> Quote:
> Originally Posted by *pepar* /forum/post/17545666
> 
> 
> What software did you use to generate the room graphic?


 Gliffy 


Just found it on a simple search. It's free and easy to use. Pretty sweet.


----------



## yacht422




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17545298
> 
> 
> Actually, you'll find the transition to phase based (modal) problems will occur between 500 and 300 Hz depending upon the room. Generally (not always) it is the first three axial modes that will cause the most audible problems. That is not to say other modes will not be problematic. If you have an RTA, the first thing to do is measure response in a right tri-corner of the room to determine exactly what your modal frequencies are. The second is to do a near field measurement of your speakers (you don't want to be fixing speaker problems with acoustical treatments).



walt here. i assume this message related to my recent post.

i lack the RTA ability - part of the problem is i am a MAC person, and the software is PC based.

measuring in a tri corner now is more difficult as i have floor to ceiling corner traps installed(rear only - the front to side wall is angled so there are a pair of 45 deg angles per "corner", in the front.)

and - dumb me, but help with axial, please.

thx

walt


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/17545941
> 
> 
> walt here. i assume this message related to my recent post.
> 
> i lack the RTA ability - part of the problem is i am a MAC person, and the software is PC based.
> 
> measuring in a tri corner now is more difficult as i have floor to ceiling corner traps installed(rear only - the front to side wall is angled so there are a pair of 45 deg angles per "corner", in the front.)
> 
> and - dumb me, but help with axial, please.
> 
> thx
> 
> walt



Axial is along the three axes of a rectangular room. Tangential and oblique are the others. Google work on Mac?


----------



## VideoDrone

I have at least 40' left of a 100' x 48" roll of 1" linacoustics left, $40 plus shipping if outside my area, dayton ohio.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Fire Man* /forum/post/17545516
> 
> 
> Looking for feedback on panel placements.



This isn't what you're asking, but it's important:


If at all possible, you should rotate your setup 90 degrees counterclockwise so the TV is in front of the window on the left side of the drawing. Put the TV on a stand if that's what it takes. The acoustic advantages are overwhelming:


* You won't have a reflecting wall right behind the seating, which will make a huge improvement in the bass response.


* You'll be able to place your surround speakers correctly, rather than directly to the sides as they are now.


* You'll have better choices for sub placement.


Then put bass traps in the corners, and absorbers at the side-wall and ceiling reflection points.


-Ethan


----------



## audhunt

Clearly there are many people here who understand the fine details of frequencies and sound coefficients on this forum. Could you please help out someone who knows absolutley nothing. I have been searching all over my region for the standard insulation everyone mentions here. However I have only been able to come up with some linacoustic in 1 1/2 inch and knauf freindly that also comes in 1 1/2 inch. Will either of these work on my side walls and screen wall?


1 1/2 in linacoustic

Sound Absorption Coefficient at Frequency

Thickness (Cycles per Second) of

in mm 125 250 500 1000 2000 4000 NRC

1/2 13 0.07 0.20 0.44 0.66 0.84 0.93 0.55

1 25 0.08 0.31 0.64 0.84 0.97 1.03 0.70

11/2 38 0.10 0.47 0.85 1.01 1.02 0.99 0.85

2 51 0.25 0.66 1.00 1.05 1.02 1.01 0.95



1 1/2 in knauf

INSERTION LOSS (DB/LF), 1/3 OCTAVE BANDS

(SOUND AND VIBRATION DESIGN AND ANALYSIS, NEBB '94)

Duct

Dimensions Sheet

Metal Nominal Wrap

Thickness Nominal Wrap

Density 63

Hz 125

Hz 250

Hz 500

Hz 1000

Hz 2000

Hz 4000

Hz

12" x 12"

(305 mm x 305 mm) 24 GA 1.5"

(38 mm) .75 PCF

(12 kg/m3) .6 .6 .6 .7 7.4 14.2 20.9

24" x 12"

(610 mm x 305 mm) 24 GA 1.5"

(38 mm) .75 PCF

(12 kg/m3) .6 .6 .6 .7 7.4 14.2 20.9

48" x 12"

(1219 mm x 305 mm) 22 GA 1.5"

(38 mm) .75 PCF

(12 kg/m3) .5 .5 .5 .6 7.4 14.1 20.9

24" x 24"

(610 mm x 610 mm) 22 GA 1.5"

(38 mm) .75 PCF

(12 kg/m3) .5 .5 .5 .6 7.4 14.1 20.9

24" x 12"

(610 mm x 305 mm) 26 GA 1.5"

(38 mm) .75 PCF

(12 kg/m3) .8 .8 .8 .8 7.5 14.2 21.0

24" x 8"

(610 mm x 203 mm) 26 GA 2"

(51 mm) .75 PCF

(12 kg/m3) 1.0 1.0 1.0 3.6 10.4 17.1 23.9


----------



## Fire Man




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17549343
> 
> 
> This isn't what you're asking, but it's important:
> 
> 
> If at all possible, you should rotate your setup 90 degrees counterclockwise so the TV is in front of the window on the left side of the drawing. Put the TV on a stand if that's what it takes. The acoustic advantages are overwhelming:
> 
> 
> * You won't have a reflecting wall right behind the seating, which will make a huge improvement in the bass response.
> 
> 
> * You'll be able to place your surround speakers correctly, rather than directly to the sides as they are now.
> 
> 
> * You'll have better choices for sub placement.
> 
> 
> Then put bass traps in the corners, and absorbers at the side-wall and ceiling reflection points.
> 
> 
> -Ethan



I have no doubt your suggestions would be more ideal, but I don't think I can shift the set up. I appreciate your input but I'll have to work with what I have. I'm not looking for perfection but to better my set up with what I have to work with. When I finally buy my own house I will do things the right way.


----------



## jvvjvv

soundprogression, pepar.....


Thanks for the input, it helps. Sp.......great charts, still trying to "totally" understand all this stuff.


Still wondering if having shelves on both side walls above ear height will hurt.


Jack


----------



## jvvjvv

One last question.......(I think)......I have to raise my center speaker 6 1/2 inches.......(on the stand)...... to get the tweeter the same height as the tweeter in the towers. How important is this?


Jack


----------



## pepar




> Quote:
> Originally Posted by *jvvjvv* /forum/post/17554881
> 
> 
> One last question.......(I think)......I have to raise my center speaker 6 1/2 inches.......(on the stand)...... to get the tweeter the same height as the tweeter in the towers. How important is this?
> 
> 
> Jack



It is optimal that all three front speakers be on the same level. That said, there is more "tolerance" in human perception wrt elevation than there is with left-to-right variations.


I think you're good to go.










Jeff


----------



## Ted White




> Quote:
> Originally Posted by *studs* /forum/post/17528667
> 
> 
> Doing a search for green glue I came upon this thread
> http://www.gearslutz.com/board/1480199-post21.html
> 
> 
> So has anyone attempted this blocking technique?



An infinitely stiff wall would theoretically not be able to create a sound wave, so many look to build such a stiff wall. Sort of like building a perpetual motion machine...


Any partition will resonate. Stiffening could only serve to raise the resonance, however that reduces the systems ability to isolate low frequencies. Generally we are looking to add mass and flex, not stiffen.


----------



## KERMIE

If one is unable to do triangle corner traps in the back of the room can you make 2 end table-like traps on each side of a couch (rear seating)


I am thinking a cube shaped:


36"H x 20"W x 30"D with a hard table top/bottom, 4 legs, filled with rigid FG and covered with GOM placed in the corner?


would that do any trapping?


----------



## Terry Montlick




> Quote:
> Originally Posted by *KERMIE* /forum/post/17566305
> 
> 
> If one is unable to do triangle corner traps in the back of the room can you make 2 end table-like traps on each side of a couch (rear seating)
> 
> 
> I am thinking a cube shaped:
> 
> 
> 36"H x 20"W x 30"D with a hard table top/bottom, 4 legs, filled with rigid FG and covered with GOM placed in the corner?
> 
> 
> would that do any trapping?



It won't work like a corner bass absorber. But you could always mock it up with a plain stack of rigid fiberglass, to see if it did anything at all beneficial.


- Terry


----------



## highcap

I plan on using the DW laminate for my screen. At almost 12 feet wide, it will take up most of my front wall. I plan on putting 2" OC around the edges and 1" along the walls, but should I try to put something behind the screen? Or would it not make a difference since the highs will bounce off the screen anyway?


----------



## Dathon

How safe are acoustic panels that use fiberglass? Is the fiberglass wrapped in a protective bag and then the acoustic cloth put over it? What is the chance of fiberglass shedding or poking through the cloth? I see several companies now offering panels made with recycled paper and polyester fibers. I think I would rather have this or foam panels, than fiberglass hanging on my walls.


----------



## Terry Montlick

If you are concerned about fiberglass, use Bonded Acoustical Cotton. Just Google it. For the same densities and thicknesses, it has equivalent performance.


- Terry


----------



## Electric_Haggis

G'day again.

I've recently put in two small but significant additions.


* A pair of 600 x 600mm acoustic tiles.


Although the rear reflections weren't nearly as audible as they had a right to be, these tiles have helped clean things up a little... and look quite decent too!












* An 850mm-wide x 1000mm-high bass trap that doubles as a corner-stand.

This is filled with triangles of 48 kg/m³ polyester bats .


Does a very nice job of knocking back the room's bass boom problem, which was its biggest failing.







































You can see the room by clicking on my signature.


Combined with the speaker placement, carpet, curtains, etc, it's now an exceptional sounding room.


Thanks to everyone here who threw in advice and suggestions!


----------



## KERMIE




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/17580870



To the experts, is this something that generally works. I like this idea as well since I cannot go from floor to ceiling in my corners.


Nice work EH


----------



## Terry Montlick




> Quote:
> Originally Posted by *KERMIE* /forum/post/17585398
> 
> 
> To the experts, is this something that generally works. I like this idea as well since I cannot go from floor to ceiling in my corners.
> 
> 
> Nice work EH



Yes. Half a loaf is better than none! BTW, Haggis is lucky to be in Australia, where they have easy access to high density (48 kg/m^3 = 3 pcf) polyester. It is tough to find in the US.


- Terry


----------



## A9X-308




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17587675
> 
> 
> Haggis is lucky to be in Australia, where they have easy access to high density (48 kg/m^3 = 3 pcf) polyester. It is tough to find in the US.
> 
> 
> - Terry



Would you have a link or brand/model please Terry?


----------



## Elill




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/17580870
> 
> 
> G'day again.
> 
> * An 850mm-wide x 1000mm-high bass trap that doubles as a corner-stand.
> 
> This is filled with triangles of 48 kg/m³ polyester bats .
> 
> 
> Does a very nice job of knocking back the room's bass boom problem, which was its biggest failing.



G'day mate,


Is that the Acoustica White HD Batts ?


I get to start our room in January from the look of it - cant wait! I'll have the same traps floor to ceiling and across the bottom of the screen in our room. Probably stuff the soffits with it as well.


----------



## Elill

Actually, while we're talking about these batts. My plan for reflection absorbers was to have:


wall - 50mm of 48kgm, 25mm of 32 kg, and 25mm of ~20kg - room


I had read somewhere that having increasing density was more effective then just 100mm of 48kg. Is this correct? I cant find the reference anywhere, been driving me nuts.


----------



## johnbomb

I have two questions regarding primitive root (skyline) diffusers:


1) How would substituting round wooden dowels for square rods affect performance?


2) How would mounting these dowels (or rods) on a curved surface, such as a large polycylindrical diffuser, affect performance?


Thanks,

John


----------



## Weasel9992




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/17580870
> 
> 
> G'day again.
> 
> I've recently put in two small but significant additions.
> 
> 
> * A pair of 600 x 600mm acoustic tiles.



Hmmm...I'd usually want to see some thicker bass trapping back there. Are you finding that you have an exaggerated low end response with your head that close to the back wall?


Frank


----------



## Gelinas

Hi All,


I am considering adding acoustic panels to my theatre. Below are a few pics.

Any advice on location? I'm thinking 2 ATS 24/48/2 Chocolate Microsuede panels could look good behind my mains. I'd probally take down the small square pictures. May even do 3 across if they fit.

Or I could do the 24/24 in place of the square pictures and one 24/28 where the long pic is.


The chocolate microsuede would be a nice match for the sofa.

Currently all that is on the one side wall is that mirror and its unlikely I could talk my wife into letting it go.

Unless I come up with a cool design to go on 3 GIK ArtPanels.

As you can see there is a big bay window to factor in as well.


I'm open to ideas with what to do in the back of the room.


The wall not pictured has a closet door, bathroom door, aquarium, open stairwell to upstairs, and big opening to kitchen.

We have a long picture over the aquarium like the one above the TV so maybe I could put another ATS 24/48/2 Chocolate Microsuede panels in this location.


Finally not sure where I could put bass traps. Only place I can thing of is the back corner behind the sofa, but isn't the sofa like a big bass trap? In addition to the fact that we have to have a table there to hold that lamp up.


thanks in advance for the assistance.


----------



## Weasel9992




> Quote:
> Originally Posted by *Gelinas* /forum/post/17596595
> 
> 
> ...Unless I come up with a cool design to go on 3 GIK ArtPanels.



That would be good right where that mirror is. The bay window is probably helping you in terms of low end response. Hmmm...I'm not sure what else you could do. You've got one of your surrounds too close to the rear corner to treat it, and I'm wary of treating the front corner with nothing on the other side.


Frank


----------



## Gelinas

Thanks for the input, Frank.

Your artpanels are indeed very cool. But also very expensive (for me).

I'll cross my fingers and hope that I am the contest winner over at your Home Theatre Shack contest. Those panels are goergous with the wood frame.


It's funny that you mention the bay window and bass...anything remotely deep makes the windows rattle.


----------



## dweltman

I have 2 questions:


1) The GIK elite bass pillar trap seems like it would more much more acceptable cosmetically (and much less expensive) than ASC Tube Traps or other large bass traps. How effective is it? My middle channel speaker is up about 10dB at 50Hz and down 6dB at 100Hz. My right and left speakers are up 6dB at 40 and 70Hz and down 4-5dB at 200Hz. This is based on my Anthem ARC measurements.


The swing is so big my Anthem ARC is not fully able to compensate for the center channel. So I clearly need room treatment. Would 2 GIK pillars be somewhat effective in the front corners? Or do I need to go with ASC or Real Traps? It is going to be difficult to convince the wife to allow me to put any traps in the room, so I need to make choices that will give me a biggest bang for each trap I convince her to put in the room. (I do understand that most of you will recommend 4 or more bass traps, but it is going to be a work in progress with the WAF. So if the GIK pillars are more acceptable cosmetically, it is a big advantage).


2) As you can guess by these numbers, my home theater is in my living room and not a dedicated space. The hardwood flooring in the master bedroom above the living room is original with the house and sqeaks terribly. So we are going to pull it up and put down new flooring next month. The contracter in question has indicated that he wants to pull up the subfloor and put in a new one to make sure that it stays quiet. So this will be the only time I will ever get access to the living room's framing, albeit the ceiling joists. Should I take the opportunity to put something in the ceiling? My room, aside from the bass issue also has an RT60 which is too high, according to a recent calibrator (umg). What should I put in, and what would be the benefit?


----------



## dweltman

My room is 13'6" x 21'3" x 8'. The listening position is 2'6" from the rear wall. I have attached a quick and dirty Giffy layout of the room, unfortunately I have to put everthing oriented along the long wall because of the windows. The doors in the schematic are actually open archways, and cannot be closed off










It's a tough space to work with










And happy Thanksgiving folks!


----------



## Weasel9992




> Quote:
> Originally Posted by *dweltman* /forum/post/17606343
> 
> 
> IThe GIF elite bass pillar trap seems like it would more much more acceptable cosmetically (and much less expensive) than ASC Tube Traps or other large bass traps. How effective is it?
> 
> 
> Would 2 GIF pillars be somewhat effective in the front corners?



I assume that you mean GIK, so I'll answer. The Pillar Bass Trap falls right in between the Monster Bass Trap and the Tri Trap in terms of effectiveness. Two in the front corners would function somewhere better than two Tri Traps in the same places. The absorption range is the same, but the PBT's absorb a little bit more than the Tri Traps given a corner placement.


Frank


----------



## dweltman




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17611819
> 
> 
> I assume that you mean GIK, so I'll answer. The Pillar Bass Trap falls right in between the Monster Bass Trap and the Tri Trap in terms of effectiveness. Two in the front corners would function somewhere better than two Tri Traps in the same places. The absorption range is the same, but the PBT's absorb a little bit more than the Tri Traps given a corner placement.
> 
> 
> Frank



Sorry about the typo


----------



## dweltman

Anyone have any suggestions about my ceiling?


----------



## KERMIE




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17587675
> 
> 
> Yes. Half a loaf is better than none! BTW, Haggis is lucky to be in Australia, where they have easy access to high density (48 kg/m^3 = 3 pcf) polyester. It is tough to find in the US.
> 
> 
> - Terry



Thanks Terry,


Does it have to be tight into the corner or can it be a inch or so off? I have trim and chair rail up currently>


----------



## Dadshouse




> Quote:
> Originally Posted by *VideoDrone* /forum/post/17549048
> 
> 
> I have at least 40' left of a 100' x 48" roll of 1" linacoustics left, $40 plus shipping if outside my area, dayton ohio.



was curious if you still have this? I sent a PM.


----------



## sebberry

I need some advice please with respect to noise control.


I live in a wood framed condo. Now before you say "end of thread, move out now".. can't.

*Upstairs noises include:*

-Heavy heel walking on both wood and carpet floors

-Constant assorted floor impact noises (perhaps from playing the Wii or something?)

-The "beep beep beep" from the microwave

-Toilet being used (not just flushed, but being peed into)


Needless to say if I can hear that you can imagine what else I can hear.


Anyway, I approached the owner upstairs to mention the noise and he had said that he could hear my movies downstairs. Now I don't usually play my stuff loud. I have all of an 8" sub and a couple of 4.5" booskshelf speakers.

*I was considering the following and am looking for some input:*


-Rip down sheetrock ceiling

-Install sound proofing insulation between ceiling joists

-Suspend new sheetrock from Green Glue clips ( http://www.greengluecompany.com/noiseproofing_clips.php )

-Use green glue and a second sheet of sheetrock


What are everyone's thoughts on this? Despite the conversation with the neighbor, the heavy walking can still be heard loud and clear and any time he has guests over noise is really noticable.


Thanks!


----------



## Jacob B

Sounds like you have done your home work.









My knowledge comes from reading up on this myself, I am not a pro. But my two cents:

As for insulation in the cavity between the beams, standard r13 should be ok, as I understand. No need for special sound proof fiberglass.

You could add two layers of drywall with GG on the underside of the upstairs floor, between the beams. That extra mass will help, especially when combined with your current plan.

Remember use acoustic seal to make it air proof.


Good luck,


Cheers

Jacob


----------



## yacht422




> Quote:
> Originally Posted by *sebberry* /forum/post/17631544
> 
> 
> I need some advice please with respect to noise control.
> 
> 
> I live in a wood framed condo. Now before you say "end of thread, move out now".. can't.
> 
> *Upstairs noises include:*
> 
> -Heavy heel walking on both wood and carpet floors
> 
> -Constant assorted floor impact noises (perhaps from playing the Wii or something?)
> 
> -The "beep beep beep" from the microwave
> 
> -Toilet being used (not just flushed, but being peed into)
> 
> 
> Needless to say if I can hear that you can imagine what else I can hear.
> 
> 
> Anyway, I approached the owner upstairs to mention the noise and he had said that he could hear my movies downstairs. Now I don't usually play my stuff loud. I have all of an 8" sub and a couple of 4.5" booskshelf speakers.
> 
> *I was considering the following and am looking for some input:*
> 
> 
> -Rip down sheetrock ceiling
> 
> -Install sound proofing insulation between ceiling joists
> 
> -Suspend new sheetrock from Green Glue clips ( http://www.greengluecompany.com/noiseproofing_clips.php )
> 
> -Use green glue and a second sheet of sheetrock
> 
> 
> What are everyone's thoughts on this? Despite the conversation with the neighbor, the heavy walking can still be heard loud and clear and any time he has guests over noise is really noticable.
> 
> 
> Thanks!



1) insulate between joists - _thicker_ absorbs more sound.

2) hang the drywall, as per your note above - but - first nail a layer of accoustiblok across the joists - then, the Drywall from clips.

N.B, : acoustiblok ( www.acoustiblok.com ) is both expensive and very heavy - you will NEED help to install. it is a thick rubber based product, difficult to manage, but very effective.

I used it on selective walls of my man cave to minimize _leaking sounds_ to the neighbors. you also want to pay attention to any shared HVAC ducts. They readily convey sound!

GOOD LUCK

walt


----------



## yacht422

the least expensive way out of what is going to be an expensive retrofit is to buy earphones - good ones - - - and you will be very happy with the surround sound, without the noise of a strong stream streaming from upstairs.

just a thought

walt


----------



## velvet396

I was watching the HGTV show Holmes on Homes (cool show) and they were fixing a townhouse with neighbor-sound issues. They used a soundproofing drywall that had the sound-deadening properties of 8 sheets of normal drywall. Check into that stuff as well. Think it might be called ToughRock or Quiet Rock... whatever it was it was drywall with a thin layer of absorbing material in the middle of it.


----------



## Ted White

The assertion that 1 sheet = 8 is a marketing tact. Not ever validated or documented. That product is excellent, but 1=8 is hype, I'm afaid.


----------



## Ted White




> Quote:
> Originally Posted by *yacht422* /forum/post/17636202
> 
> 
> 1) insulate between joists - _thicker_ absorbs more sound.
> 
> Not necessarily so. Tests show that in a joist cavity, a 50% filled cavity is about the same as a 100% filled cavity.
> 
> 
> 2) hang the drywall, as per your note above - but - first nail a layer of accoustiblok across the joists - then, the Drywall from clips.
> 
> Disaster. You've created a triple leaf. Absolutely this method is to be avoided at all costs.
> 
> 
> N.B, : acoustiblok ( www.acoustiblok.com ) is both expensive and very heavy - you will NEED help to install. it is a thick rubber based product, difficult to manage, but very effective.
> 
> Works about as well as anything else that heavy... like drywall.



The overall solution doesn't have to be so complicated.


----------



## Ted White




> Quote:
> Originally Posted by *sebberry* /forum/post/17631544
> 
> 
> I need some advice please with respect to noise control.
> 
> 
> I live in a wood framed condo. Now before you say "end of thread, move out now".. can't.
> 
> *Upstairs noises include:*
> 
> -Heavy heel walking on both wood and carpet floors
> 
> -Constant assorted floor impact noises (perhaps from playing the Wii or something?)
> 
> -The "beep beep beep" from the microwave
> 
> -Toilet being used (not just flushed, but being peed into)
> 
> 
> Needless to say if I can hear that you can imagine what else I can hear.
> 
> 
> Anyway, I approached the owner upstairs to mention the noise and he had said that he could hear my movies downstairs. Now I don't usually play my stuff loud. I have all of an 8" sub and a couple of 4.5" booskshelf speakers.
> 
> *I was considering the following and am looking for some input:*
> 
> 
> -Rip down sheetrock ceiling
> 
> -Install sound proofing insulation between ceiling joists
> 
> -Suspend new sheetrock from Green Glue clips ( http://www.greengluecompany.com/noiseproofing_clips.php )
> 
> -Use green glue and a second sheet of sheetrock
> 
> 
> What are everyone's thoughts on this? Despite the conversation with the neighbor, the heavy walking can still be heard loud and clear and any time he has guests over noise is really noticable.
> 
> 
> Thanks!


 http://www.soundproofingcompany.com/...fing_ceilings/ 


This article describes various ceiling solutions. Pros and cons.


----------



## giomania




> Quote:
> Originally Posted by *yacht422* /forum/post/17636202
> 
> 
> You also want to pay attention to any shared HVAC ducts. They readily convey sound!
> 
> 
> walt



I have this problem now with the metal ductwork in my house. Is there any solution to mitigate this with the existing ductwork?


Thanks.


Mark


----------



## velvet396




> Quote:
> Originally Posted by *Ted White* /forum/post/17641169
> 
> 
> The assertion that 1 sheet = 8 is a marketing tact. Not ever validated or documented. That product is excellent, but 1=8 is hype, I'm afaid.



unfortunate that it lacks that testing, however on the show it solved their problem. They did a good job of showing their testing before and after the installation and showed the difference it made. It's not normally a program to shill a specific product either.


----------



## Ted White

Sorry to be curt, but it's a TV show that really demonstrated nothing. If someone wants to demonstrate something, they head to a lab (which they have done)


Note that I previously stated that this is a good product. Simply stating that the 1=8 is hype not fact.


----------



## Elill




> Quote:
> Originally Posted by *Elill* /forum/post/17589474
> 
> 
> Actually, while we're talking about these batts. My plan for reflection absorbers was to have:
> 
> 
> wall - 50mm of 48kgm, 25mm of 32 kg, and 25mm of ~20kg - room
> 
> 
> I had read somewhere that having increasing density was more effective then just 100mm of 48kg. Is this correct? I cant find the reference anywhere, been driving me nuts.



Anyone know?


----------



## glaufman




> Quote:
> Originally Posted by *velvet396* /forum/post/17643653
> 
> 
> It's not normally a program to shill a specific product either.



Disagree. Although I love the show, and have had that episode tivo'd permanantly since it originally aired years ago, there are a few products that they shamelessly hype over and over again. Not that they're bad products, but c'mon.


----------



## velvet396




> Quote:
> Originally Posted by *glaufman* /forum/post/17647418
> 
> 
> Disagree. Although I love the show, and have had that episode tivo'd permanantly since it originally aired years ago, there are a few products that they shamelessly hype over and over again. Not that they're bad products, but c'mon.



didn't know that, new to watching the series. Still fun to watch and he's like the Jack Bauer of home construction.


----------



## Weasel9992




> Quote:
> Originally Posted by *Elill* /forum/post/17643930
> 
> 
> Anyone know?



I mean, that's fine...there's certainly nothing wrong with that plan. I don't know that you'll get *better* results than if you made all of your panels with 48kg/m3 though.


Frank


----------



## glaufman




> Quote:
> Originally Posted by *velvet396* /forum/post/17647668
> 
> 
> didn't know that, new to watching the series. Still fun to watch and he's like the Jack Bauer of home construction.



Yup.. I can't seem to find new episodes (or even ones I haven't seen) but I do love the show. My buddy and I help each other out on home improvement/repair projects. When we're thinking of cutting a corner, we can actually hear Mike (or Frank, or Dan) talking to the camera saying "Now LOOK at what THIS guy did... SHAMEFUL"...


----------



## erkq




> Quote:
> Originally Posted by *glaufman* /forum/post/17648004
> 
> 
> Yup.. I can't seem to find new episodes (or even ones I haven't seen) but I do love the show. My buddy and I help each other out on home improvement/repair projects. When we're thinking of cutting a corner, we can actually hear Mike (or Frank, or Dan) talking to the camera saying "Now LOOK at what THIS guy did... SHAMEFUL"...



I'm "that guy"...


----------



## yacht422




> Quote:
> Originally Posted by *giomania* /forum/post/17643487
> 
> 
> I have this problem now with the metal ductwork in my house. Is there any solution to mitigate this with the existing ductwork?
> 
> 
> Thanks.
> 
> 
> Mark



the obvious answer is to speak with a HVAC person. metal ducts are impossible to replace unless exposed, which few are.

- - - and replacing is what is in order .

replacing with the newer round insulated non-metal ducts solves the problem, but, again, need to have access.

there are diaphrams that can be placed in the HVAC "run" that will help - not a total solution, however.

good luck

walt


----------



## glaufman




> Quote:
> Originally Posted by *erkq* /forum/post/17648559
> 
> 
> I'm "that guy"...



Well, um, thanks for the great programming?


----------



## R Harkness

Advice Needed:


I have my stand mounted L/R speakers fairly close to the room corners on either side of the projection screen. I had left the dry-wall open on the sides of the screen and filled it with 4" fibre-board to get at least some bass trapping if possible. I plan to add another 4" thickness of the fibre-board (OFI 48) to make the trap 8" thick.


In front of the 8" of fibre board in the room corners are 5 hanging panels of black velvet, on each side of the screen. These travel horizontally to mask different widths of the screen, and when opened the panels stack 5 deep on each side, in the room corner. So I'd presume that adds a tiny bit more absorption.


BUT....the issue is that I'm considering replacing one or two of the velvet panels with a light-weight board material, then wrapping the velvet around the stiff material, to get a nice, flat velvet-covered panel for masking.


I'm looking at using 4mm thick *Coroplast* - a white corrugated plastic sheet. So it's very thin and mostly hollow (due to corrugation - think cardboard). _


ETA picture - this is what I'm talking about, 4mm thick:










I don't intend to replace all 5 panels on each side of my screen with this Coroplast, only one or perhaps two of the panels per side. So a max of 4mm to 8mm of Coroplast would go in the room corners._


Do I need to worry about putting such a panel behind my speaker, between the speaker and the acoustic OFI 48 fibre-board I'm using as "bass" traps?

Will it stop the sound from being absorbed or reduce the effectiveness of

the acoustic absorption behind the speaker?


I'm figuring probably not - that at the type of bass frequencies I'd hope to be absorbing, such a thin piece of corrugated plastic material wouldn't "stop" the sound from being absorbed by the bass traps behind it. But thought I should check before I go ahead.


Thanks.


----------



## Techlord

Wow this thread is a little more into tearing down drywall, I live in a condo and am just looking for acoustic treatments to hang on my walls. My living room is 12 ft. x 18 ft. and I'm sitting 9 1/2 feet from my flat panel display, my room is rectangular but almost square. My problem is I have my back to a wall about 1ft. behind my head, sliding door on my left and to the right go's into my dinning room am tired of the constant reverb ecos, my AV gear consists of MKsound 750 THX 5.1 speaker system, Denon AVR-5700, Oppo BDP-83SE and a Samsung LN52B750 series LCD. My seeting vtwo 12ft I'm not intrested in buying new AV gear with room corrections (tight budget) and would like something affordable that I can just hang on my walls. I have thick carpeting with area rug and nothing in-between me and my speakers. Thank you for any reply/advice, Techlord.










I have my seating position between the wall that meaures 12ft., so my width would be 18ft.


----------



## nathan_h

The mirror trick is a good one. Thick panels where sound bounces like a pool ball from the speaker, off a wall or ceiling or floor, to your ear.

http://www.realtraps.com/art_room-setup.htm 


-


Secondarily, bass trapping in the corners.

http://www.realtraps.com/placing_mt.htm 


-


From the GIK web site, a picture of how it might look. Since you are sitting at the back wall, consider changing that. Sitting out into the room will sound much better.


----------



## Techlord




> Quote:
> Originally Posted by *nathan_h* /forum/post/17677773
> 
> 
> The mirror trick is a good one. Thick panels where sound bounces like a pool ball from the speaker, off a wall or ceiling or floor, to your ear.
> 
> http://www.realtraps.com/art_room-setup.htm
> 
> 
> -
> 
> 
> Secondarily, bass trapping in the corners.
> 
> http://www.realtraps.com/placing_mt.htm
> 
> 
> -
> 
> 
> From the GIK web site, a picture of how it might look. Since you are sitting at the back wall, consider changing that. Sitting out into the room will sound much better.



It's impossible to do it like the picture, I would be looking at my sliding glass door. If you turn it around I'm looking at my kitchen bar area, the way it is is the way it must be done. Here better yet hear are some pictures, excuse the mess I've been painting. My camera makes my place look half as large.


Thank you soo much for you help so far!


----------



## Rob Will

A civic group is seeking to construct a multi-media theater inside of a local museum. Noise transmission to other parts of the building will not be a major issue because of the proposed theater location. What does seem to be a problem is that the existing space has a 16' high 3-faceted vaulted ceiling that concentrates reflected sound back toward the center of the room. Frankly, the existing room sounds horrible!










Otherwise, the room is basically a 27' x 31' rectangle with the screen wall (front) being 27' x 11' high. A 7.1 surround system is proposed with the LCR speakers behind an AT screen.


There are approx. 47 seats in the proposed theater with the back row adjacent to the back (27') wall. The seating is on risers with the back row elevated approx 4' above the main floor.


1.) Will a 2" fiberglass ceiling tile system help kill the concentrated reflections from the ceiling?


2.) How would you treat the screen wall?


3.) How would you treat the back wall?


4.) How would you treat the sides?


5.) If placing bass traps at a 45 degree angle in the corners can't work due to aesthetics and space limitations, how would you kill boomy bass?



Thanks,

Rob


----------



## CJO

Rob- do you have the budget to hire a professional? Especially with the existing conditions and restraints you have, you would end up with a much better result.


CJ


----------



## Weasel9992




> Quote:
> Originally Posted by *CJO* /forum/post/17679180
> 
> 
> Rob- do you have the budget to hire a professional? Especially with the existing conditions and restraints you have, you would end up with a much better result.
> 
> 
> CJ



I completely, totally agree.


Frank


----------



## Weasel9992




> Quote:
> Originally Posted by *Techlord* /forum/post/17678116
> 
> 
> It's impossible to do it like the picture, I would be looking at my sliding glass door. If you turn it around I'm looking at my kitchen bar area, the way it is is the way it must be done. Here better yet hear are some pictures, excuse the mess I've been painting. My camera makes my place look half as large.



That's going to be the tough way to do it...even taking into account that the room is larger than the picture makes it out to be, there's a very short distance between your speakers and the wall behind your head. You'll want thick bass trapping on the back wall behind your head (which may mean moving the couch out from the wall another 6") and at least 4" panels on the front wall behind the speakers. To say it in more general terms, you'll want as much 50-250Hz trapping as you can stand to look at.


Frank


----------



## Rob Will

Here's the problem:


Thus far we only have funding for the preliminary architectural work. Things like:

Overall space considerations

Structural engineering

Electrical engineering

Fire codes

etc.


IF we can advance the project, and there proves to be enough space within the museum to make this happen, and the structural works out, we are going to address the topics of acoustics and outfitting as the next phase of our fund raising. So yes, acoustic professionals WILL be involved BEFORE the design is complete.


Here's our chicken-egg scenario:

We need to get a general feel for the space considerations and overall $$$. Things like: will we have a baffle wall? Will we be looking at a drop ceiling?


The reason that we need to ask these PRELIMINARY questions is because they ultimately impact whether or not the project is doable. For example things like relocating the sprinkler system ($$$).


So these are very preliminary questions to get a feel for the overall space.

We are not going to get formal acoustic work done until we see that things like structural come back OK and will handle the weight of 50 people as a live load.


This is NOT a do it yourself sort of project and we are seeking input from numerous company reps at the highest levels. We even put on a "theater tech" show to help educate ourselves. The Christie rep brought in a 10,000 lumen projector etc. Many other area museums and school districts attended our show and it was a great success.


Any GENERAL SUGGESTIONS that you have will be most helpful in steering the ultimate outcome of this project:







.


Thanks,

Rob


----------



## Techlord




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17679780
> 
> 
> That's going to be the tough way to do it...even taking into account that the room is larger than the picture makes it out to be, there's a very short distance between your speakers and the wall behind your head. You'll want thick bass trapping on the back wall behind your head (which may mean moving the couch out from the wall another 6") and at least 4" panels on the front wall behind the speakers. To say it in more general terms, you'll want as much 50-250Hz trapping as you can stand to look at.
> 
> 
> Frank



I am new at this, where might I find some affordable 50-250Hz trapping and what does it look like? Perhaps they come in colors, I will look at mud on the wall to get better sound!










Thank you Weasel,

Techlord!


----------



## Rob Will

OK guys, has anyone used a decorative column as a bass trap in the four corners of a room?


What would happen if you made a 4-sided box with the outer skin of 1/4" pegboard (Masonite)- then experimented with various acoustic materials inside the "column"?


The dimensions of the column might be something like 12" x 12" x 96" tall. It would be fabric wrapped and positioned a couple of inches from each corner of the room.


Anybody venture a guess as to what the sound absorption characteristics of this "column" would be?


Thanks,

Rob


----------



## Techlord

I have googled 50-250Hz trapping treatments and comes up with nothing?


----------



## pepar




> Quote:
> Originally Posted by *Techlord* /forum/post/17685117
> 
> 
> I have googled 50-250Hz trapping treatments and comes up with nothing?


 StudioTips


----------



## Techlord




> Quote:
> Originally Posted by *pepar* /forum/post/17685977
> 
> StudioTips



Thank you for the link pepar, but I just want to buy it and hang it however strange it might look.


----------



## rhcorolla




> Quote:
> Originally Posted by *Techlord* /forum/post/17686077
> 
> 
> Thank you for the link pepar, but I just want to buy it and hang it however strange it might look.



Phone or e-mail realtraps.com and/or gikacoustics.com. If you provide them your A/V room lay-out/ equipment/ listening preferences/ restrictions/ budget/ etc.; they have expertise & products to acoustically treat your room a little, a lot, or somewhere in-between. Their websites also have excellent articles/ theory/ diagrams/ etc. re: acoustics/ sound treatments/ etc..


If you want to DIY, then a LOT of research, due diligience & hard work is needed.


----------



## Ethan Winer




> Quote:
> Originally Posted by *rhcorolla* /forum/post/17686727
> 
> 
> Phone or e-mail realtraps.com and/or gikacoustics.com.



Exactly, and thanks.










DIY is great, and I help people with that all the time. But not everyone is up for that. Another reason to buy from a vendor is the good ones will tell you what you need and where to put it. For many people that's a lot better than spending literally weeks doing research, and still not being certain they have the correct strategy.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *Techlord* /forum/post/17685117
> 
> 
> I have googled 50-250Hz trapping treatments and comes up with nothing?



A well-built 4" absorber will cover much of that...you'll need thicker absorbers to get down into the 50's.


Frank


----------



## R Harkness

BUMP:


If I'm going to make these panels it has to be by the weekend, so I'm hoping someone can help me with some info on the question below.

Many thanks.



> Quote:
> Originally Posted by *R Harkness* /forum/post/17674752
> 
> 
> Advice Needed:
> 
> 
> I have my stand mounted L/R speakers fairly close to the room corners on either side of the projection screen. I had left the dry-wall open on the sides of the screen and filled it with 4" fibre-board to get at least some bass trapping if possible. I plan to add another 4" thickness of the fibre-board (OFI 48) to make the trap 8" thick.
> 
> 
> In front of the 8" of fibre board in the room corners are 5 hanging panels of black velvet, on each side of the screen. These travel horizontally to mask different widths of the screen, and when opened the panels stack 5 deep on each side, in the room corner. So I'd presume that adds a tiny bit more absorption.
> 
> 
> BUT....the issue is that I'm considering replacing one or two of the velvet panels with a light-weight board material, then wrapping the velvet around the stiff material, to get a nice, flat velvet-covered panel for masking.
> 
> 
> I'm looking at using 4mm thick *Coroplast* - a white corrugated plastic sheet. So it's very thin and mostly hollow (due to corrugation - think cardboard). _
> 
> 
> ETA picture - this is what I'm talking about, 4mm thick:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I don't intend to replace all 5 panels on each side of my screen with this Coroplast, only one or perhaps two of the panels per side. So a max of 4mm to 8mm of Coroplast would go in the room corners._
> 
> 
> Do I need to worry about putting such a panel behind my speaker, between the speaker and the acoustic OFI 48 fibre-board I'm using as "bass" traps?
> 
> Will it stop the sound from being absorbed or reduce the effectiveness of
> 
> the acoustic absorption behind the speaker?
> 
> 
> I'm figuring probably not - that at the type of bass frequencies I'd hope to be absorbing, such a thin piece of corrugated plastic material wouldn't "stop" the sound from being absorbed by the bass traps behind it. But thought I should check before I go ahead.
> 
> 
> Thanks.


----------



## Techlord




> Quote:
> Originally Posted by *rhcorolla* /forum/post/17686727
> 
> 
> Phone or e-mail realtraps.com and/or gikacoustics.com. If you provide them your A/V room lay-out/ equipment/ listening preferences/ restrictions/ budget/ etc.; they have expertise & products to acoustically treat your room a little, a lot, or somewhere in-between. Their websites also have excellent articles/ theory/ diagrams/ etc. re: acoustics/ sound treatments/ etc..
> 
> 
> If you want to DIY, then a LOT of research, due diligience & hard work is needed.



Thank you rhcorolla, I called Realtraps and they have Guilford Minitraps 2 by 4 foot size panel absorbers for $179-$249 and can special order larger sizes available, up to 4 by 8 feet! I think I'll be getting three 4 x 8 foot HF absorbing panels to tame the high frequencies ecos, two verticals and the other horizontal along the top behind of my 52" LCD display. Do you think I should invest in corner absorbing panels or are three 4 x 8 foot HF absorbing panels enough?


----------



## rhcorolla




> Quote:
> Originally Posted by *Techlord* /forum/post/17690806
> 
> 
> Thank you rhcorolla, I called Realtraps and they have Guilford Minitraps 2 by 4 foot size panel absorbers for $179-$249 and can special order larger sizes available, up to 4 by 8 feet! I think I'll be getting three 4 x 8 foot HF absorbing panels to tame the high frequencies ecos, two verticals and the other horizontal along the top behind of my 52" LCD display. Do you think I should invest in corner absorbing panels or are three 4 x 8 foot HF absorbing panels enough?



Bass trap-wise, best bang for the buck is to treat as many corners as you reasonably can either by straddling a 4” min. thk. flat panel at corners or getting even more absorption w/ super chunk or solid fiberglass corner adsorbers. You have 12 corners in a room (4 vertical corners, 4 floor-wall corners & 4 ceiling-wall) that can potentially be treated. Of course furniture/ room openings, windows, aesthetics, wife acceptance factors, budget play into these choices.


This Real Traps article discusses bass traps.

http://www.realtraps.com/lf-noise.htm 


A good initial investment is to utilize a Radio Shack or equivalent Sound Pressure Level meter ($50 or so) & utilize test tones (mp3 file in referenced article for 10 Hz- 300 Hz tones) to determine where you have peaks & nulls in your particular room & primary listening area. Is your room “live” or “dead” or somewhere “in-between”? YOUR specific set-up & room limitations dictate best path forward.

*Again, talking to the fine folks at Real Traps & GIK Acoustics (who have forgotten more about acoustics than I or most posters on this thread will ever know) are the best sources for your particular set-up/ situation.*


Edit: Techlord, At the risk of information overload, here are two excellent articles re: room acoustics & sound treatments from the (2) recommended subject matter experts. Don’t be intimidated by all the info. Just focus on key points re: best placement for early reflection panels & bass traps. The 38% rule for room set-up is also very helpful.

http://www.realtraps.com/art_room-setup.htm 

http://www.gikacoustics.com/education.html


----------



## pepar




> Quote:
> Originally Posted by *Techlord* /forum/post/17690806
> 
> 
> Thank you rhcorolla, I called Realtraps and they have Guilford Minitraps 2 by 4 foot size panel absorbers for $179-$249 and can special order larger sizes available, up to 4 by 8 feet! I think I'll be getting three 4 x 8 foot HF absorbing panels to tame the high frequencies ecos, two verticals and the other horizontal along the top behind of my 52" LCD display. Do you think I should invest in corner absorbing panels or are three 4 x 8 foot HF absorbing panels enough?



I'd like to throw something out there that a consumer of acoustical treatments should know in order to make a completely informed buying decision. In bulk from an HVAC insulation distributor, a 2x4x2" sheet of OC 703, the material that goes into the panels being discussed here, is about $6-$8. The others here make good points about DIY research taking time and companies like Realtraps and GIK doing basic analysis and recommending what should go where, but without the underlying raw material cost you really don't have the whole picture.


----------



## Spaceman

How kid-proof /pet-proof is the GOM fabric? I have visions of my cats using the walls as scratching posts and my kids.....well they're kids. Is it pretty durable? I prefer the seamless look of Big's walls above and below a chair rail but am thinking the panel approach may make repairs easier. Any thoughts?


----------



## pepar




> Quote:
> Originally Posted by *spacemanlee* /forum/post/17692805
> 
> 
> How kid-proof /pet-proof is the GOM fabric? I have visions of my cats using the walls as scratching posts and my kids.....well they're kids. Is it pretty durable? I prefer the seamless look of Big's walls above and below a chair rail but am thinking the panel approach may make repairs easier. Any thoughts?



No, it's not *that* durable. You will not be happy with your cats if they use your panels as scratch pads. And the panel covering would need to be REPLACED; there is no repair that I can think of that would fix the damage.


Parent up and prevent the damage from happening in the first place!


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/17692769
> 
> 
> I'd like to throw something out there that a consumer of acoustical treatments should know in order to make a completely informed buying decision. In bulk from an HVAC insulation distributor, a 2x4x2" sheet of OC 703, the material that goes into the panels being discussed here, is about $6-$8. The others here make good points about DIY research taking time and companies like Realtraps and GIK doing basic analysis and recommending what should go where, but without the underlying raw material cost you really don't have the whole picture.



That's true, but also in the interest of fairness it's only true if you can get the insulation material locally. After you add other materials, a DIY 2" trap is typically around $20 (for just fabric-wrapped insulation), or around $30 (for a panel with an internal frame). That doesn't count installation hardware or the time it takes to make it though.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17693868
> 
> 
> That's true, but also in the interest of fairness it's only true if you can get the insulation material locally. After you add other materials, a DIY 2" trap is typically around $20 (for just fabric-wrapped insulation), or around $30 (for a panel with an internal frame). That doesn't count installation hardware or the time it takes to make it though.
> 
> 
> Frank



Yes, Frank, I neglected to include the important caveat that a local supplier is needed as shipping and handling of a product as voluminous as fiberglass can quickly inflate the per sheet price.


Jeff


----------



## gdc




> Quote:
> Originally Posted by *R Harkness* /forum/post/17690572
> 
> 
> BUMP:
> 
> 
> If I'm going to make these panels it has to be by the weekend, so I'm hoping someone can help me with some info on the question below.
> 
> Many thanks.



What you are planning to do should have NO adverse effect on any other bass trapping you do. Of course, it will have no positive effect either.


It looks like those panels could be slightly reflective at higher frequencies, though.


----------



## gdc




> Quote:
> Originally Posted by *Rob Will* /forum/post/17684647
> 
> 
> OK guys, has anyone used a decorative column as a bass trap in the four corners of a room?
> 
> 
> What would happen if you made a 4-sided box with the outer skin of 1/4" pegboard (Masonite)- then experimented with various acoustic materials inside the "column"?
> 
> 
> The dimensions of the column might be something like 12" x 12" x 96" tall. It would be fabric wrapped and positioned a couple of inches from each corner of the room.
> 
> 
> Anybody venture a guess as to what the sound absorption characteristics of this "column" would be?
> 
> 
> Thanks,
> 
> Rob



Absorption would not be great. You need more thickness.


In addition, you want to straddle the corner.


Finally, the masonite might reflect some energy back into the room. Ideally, you want an open face (fabric covered) to the sound energy coming INTO the corner. Without that, the 'bass doesn't all enter the trap.'


----------



## Techlord




> Quote:
> Originally Posted by *rhcorolla* /forum/post/17692625
> 
> 
> Bass trap-wise, best bang for the buck is to treat as many corners as you reasonably can either by straddling a 4” min. thk. flat panel at corners or getting even more absorption w/ super chunk or solid fiberglass corner adsorbers. You have 12 corners in a room (4 vertical corners, 4 floor-wall corners & 4 ceiling-wall) that can potentially be treated. Of course furniture/ room openings, windows, aesthetics, wife acceptance factors, budget play into these choices.
> 
> 
> This Real Traps article discusses bass traps.
> 
> http://www.realtraps.com/lf-noise.htm
> 
> 
> A good initial investment is to utilize a Radio Shack or equivalent Sound Pressure Level meter ($50 or so) & utilize test tones (mp3 file in referenced article for 10 Hz- 300 Hz tones) to determine where you have peaks & nulls in your particular room & primary listening area. Is your room “live” or “dead” or somewhere “in-between”? YOUR specific set-up & room limitations dictate best path forward.
> 
> *Again, talking to the fine folks at Real Traps & GIK Acoustics (who have forgotten more about acoustics than I or most posters on this thread will ever know) are the best sources for your particular set-up/ situation.*
> 
> 
> Edit: Techlord, At the risk of information overload, here are two excellent articles re: room acoustics & sound treatments from the (2) recommended subject matter experts. Don’t be intimidated by all the info. Just focus on key points re: best placement for early reflection panels & bass traps. The 38% rule for room set-up is also very helpful.
> 
> http://www.realtraps.com/art_room-setup.htm
> 
> http://www.gikacoustics.com/education.html



My room is "live" and more "reflective" that "live" in the extreme, I believe if I can tame the "reflectiveness it would sound much better! I never thought to use my Radio Shac Sound Pressure Level meter for finding peaks & nulls in my room, I guess it has more uses than I thought!







You have mentioned Bass traps, I have an MKSound THX 5.1 sound system where anything below 80Hz go's to the non-ported 12" subwoofer. I only have two corners that are within close proximity to my speakers, the other two corners are bending into the dining room. I definitely need high frequency absorbing panels behind my speakers and flat panel display if I understand it correctly, I will read through those links probably more than once, I'm not easily the kind that would give up do to overload!










Thank you,

Techlord.


----------



## Techlord




> Quote:
> Originally Posted by *pepar* /forum/post/17692769
> 
> 
> I'd like to throw something out there that a consumer of acoustical treatments should know in order to make a completely informed buying decision. In bulk from an HVAC insulation distributor, a 2x4x2" sheet of OC 703, the material that goes into the panels being discussed here, is about $6-$8. The others here make good points about DIY research taking time and companies like Realtraps and GIK doing basic analysis and recommending what should go where, but without the underlying raw material cost you really don't have the whole picture.



So you think I could build my own wooden frame and buy these inexpensive insulation? For the record I do not have early reflection between me and my speakers, my ear is the first thing sounds will intersect.


----------



## rhcorolla




> Quote:
> Originally Posted by *Techlord* /forum/post/17696137
> 
> 
> So you think I could build my own wooden frame and buy these inexpensive insulation? For the record I do not have early reflection between me and my speakers, my ear is the first thing sounds will intersect.










Woah! You really need to read up on the subject as you have first reflection/ early reflection sound waves bouncing all over creation: off your floors, ceiling, side walls, back wall & front wall that come to your listening area. Sound treatment panels in the right locations help minimize/ eliminate these problems to prevent coloration, provide more detail & hopefully provide a flatter frequency response to your ears (improving peaks & nulls @ certain frequencies).


----------



## Terry Montlick




> Quote:
> Originally Posted by *Rob Will* /forum/post/17684647
> 
> 
> Anybody venture a guess as to what the sound absorption characteristics of this "column" would be?



This is a Helmholtz absorber. My guestimate is that it would have peak absorption in the range 200-400 Hz. The material you stuff it with can effect the bandwidth (tightness of the peak) some. It won't reach very much below 100 Hz, though.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Techlord* /forum/post/17696137
> 
> 
> So you think I could build my own wooden frame and buy these inexpensive insulation?



That depends on your shop skills, motivation level and proximity to an HVAC insulation distributor . I built my own .



> Quote:
> For the record I do not have early reflection between me and my speakers, my ear is the first thing sounds will intersect.



If you have a ceiling and floor between you and the speakers, you have early reflections. Even if your room is wide you will have early reflections. Yes, the line between your speakers and your ears is the most direct path, but it's not that the "early" reflections arrive *before* the direct sound, it's that they arrive just after and blur the image.


----------



## Rob Will




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17696374
> 
> 
> This is a Helmholtz absorber. My guestimate is that it would have peak absorption in the range 200-400 Hz. The material you stuff it with can effect the bandwidth (tightness of the peak) some. It won't reach very much below 100 Hz, though.- Terry



Terry, Thanks for the info. Did your answer take into account that I was considering the use of 1/4" _perforated_ pegboard? Would a true Helmholtz absorber have a non-perforated skin? Are there other skin materials that would provide better / different absorption characteristics?


Thanks again,

Rob


----------



## Terry Montlick




> Quote:
> Originally Posted by *Rob Will* /forum/post/17697278
> 
> 
> Terry, Thanks for the info. Did your answer take into account that I was considering the use of 1/4" _perforated_ pegboard? Would a true Helmholtz absorber have a non-perforated skin? Are there other skin materials that would provide better / different absorption characteristics?
> 
> 
> Thanks again,
> 
> Rob



Yes. I assumed common perf board with 1/4" holes on 1" centers.


To make a Helmholtz resonator, you need a chamber with holes. You can have one hole, or a number of them on a regular grid. The hole size, spacing, material thickness (I assumed 1/4") and resonator volume all determine the absorption.


----------



## R Harkness

Terry Montlick,


Would you mind tackling the question I have on this page (see above, with photo) about the effects of putting 4mm thick Coroplast in front of my bass trap area?


(And, if it will act as a barrier to the effectiveness of the bass trap, would heavily perforating the Coroplast help?).


Thanks.


----------



## Terry Montlick




> Quote:
> Originally Posted by *R Harkness* /forum/post/17697385
> 
> 
> Terry Montlick,
> 
> 
> Would you mind tackling the question I have on this page (see above, with photo) about the effects of putting 4mm thick Coroplast in front of my bass trap area?
> 
> 
> (And, if it will act as a barrier to the effectiveness of the bass trap, would heavily perforating the Coroplast help?).



I don't know of any acoustic use for corrugated plastic. It can only interfere with the operation of a bass absorber.


- Terry


----------



## R Harkness




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17697414
> 
> 
> I don't know of any acoustic use for corrugated plastic. It can only interfere with the operation of a bass absorber.
> 
> 
> - Terry



(Sigh)...thanks Terry.


Back to the drawing board for me...


----------



## Rob Will

Does anyone have pics of corner bass traps disguised as decorative columns?

I'm trolling for ideas regarding a theater space in a public building.

The traps would need to be durable enough for groups of school kids to visit the theater.


The space currently has some serious reflections.

Here are the reverb times:








32Hz - 0.8 sec.
63Hz - 1.48 sec.
125Hz - 1.10 sec.
250Hz. - 1.44 sec.
500Hz - 1.48Hz.
1000Hz. - 1.18 sec.
2000Hz. - 1.06
4000Hz. - 0.61 sec.
8000Hz. - 0.33 sec.


Thanks,

Rob


----------



## Techlord




> Quote:
> Originally Posted by *pepar* /forum/post/17696679
> 
> 
> That depends on your shop skills, motivation level and proximity to an HVAC insulation distributor . I built my own .
> 
> 
> 
> If you have a ceiling and floor between you and the speakers, you have early reflections. Even if your room is wide you will have early reflections. Yes, the line between your speakers and your ears is the most direct path, but it's not that the "early" reflections arrive *before* the direct sound, it's that they arrive just after and blur the image.



Yes it's that after effects that blur the image that I trying to get rid of, I probably hear the same blurred image over and over again killing the original image! So would you recommend the Guilford MiniTraps that are 2 by 4 feet, and 2.75 inches thick which are good for reflection control? I will probably get a few for behind my speakers to start with and go from there.


----------



## mrkplatt

Attached is the layout of my room showing the locations of the ATS Traps that I have now. Three 4" traps (2' wide floor to ceiling - 7' ceiling in the room) in the wall-to-wall corners and 2'x4'x2" on the walls.


I'm wondering if anyone can advise me on how to treat my "tunnel" and "cave". A tunnel at the entry way in the front of the theater, and a cave in the rear of the theater.


Thanks for any advice!

 

HT Detail 20091211.pdf 19.62890625k . file


----------



## bpape




> Quote:
> Originally Posted by *Rob Will* /forum/post/17698079
> 
> 
> Does anyone have pics of corner bass traps disguised as decorative columns?
> 
> I'm trolling for ideas regarding a theater space in a public building.
> 
> The traps would need to be durable enough for groups of school kids to visit the theater.
> 
> 
> The space currently has some serious reflections.
> 
> Here are the reverb times:
> 
> 
> 
> 
> 
> 
> 
> 
> 32Hz - 0.8 sec.
> 63Hz - 1.48 sec.
> 125Hz - 1.10 sec.
> 250Hz. - 1.44 sec.
> 500Hz - 1.48Hz.
> 1000Hz. - 1.18 sec.
> 2000Hz. - 1.06
> 4000Hz. - 0.61 sec.
> 8000Hz. - 0.33 sec.
> 
> 
> Thanks,
> 
> Rob



What are the dimensions of the space and are those measured with or without people in the space? The numbers may be good, OK, or bad depending.


Bryan


----------



## Rob Will




> Quote:
> Originally Posted by *bpape* /forum/post/17709680
> 
> 
> What are the dimensions of the space and are those measured with or without people in the space? The numbers may be good, OK, or bad depending.
> 
> 
> Bryan



The proposed space is about 26' wide x 31' deep and has a 3-faceted vaulted ceiling 16' high.


At this time, we are just trying to get some basic layout ideas.


As far as having people in the room for a reverb measurement(?), it does not yet exist with seating - for now just a museum space with a few exhibits - so I can't measure that.


My question would be: How can you take a space with so much reverb that it is hard to understand speech and make it a high quality theater? How can 1.5 second reverb times EVER be a good thing?










Thanks,

Rob


----------



## pepar




> Quote:
> Originally Posted by *Rob Will* /forum/post/17712439
> 
> 
> The proposed space is about 26' wide x 31' deep and has a 3-faceted vaulted ceiling 16' high.
> 
> 
> At this time, we are just trying to get some basic layout ideas.
> 
> 
> As far as having people in the room for a reverb measurement(?), it does not yet exist with seating - for now just a museum space with a few exhibits - so I can't measure that.
> 
> 
> My question would be: How can you take a space with so much reverb that it is hard to understand speech and make it a high quality theater? *How can 1.5 second reverb times EVER be a good thing?*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks,
> 
> Rob



That's rhetorical, right?


----------



## Rob Will




> Quote:
> Originally Posted by *pepar* /forum/post/17712560
> 
> 
> That's rhetorical, right?



Yes, as opposed to outright sarcasm like:


"Everyone on this forum is so forthcoming with information"


I'm just trying to get a basic understanding of some acoustical issues to convey to our architect. Fortunately, Ethan Winer has gone to a lot of effort to share his knowledge and posted some VERY informative articles on the net. I will be sure and tell the architect about RealTraps acoustic ceiling tile and other cost-effective products







.


Aside from that, I am trying to get a feel for how much space we need behind the screen, approx speaker sizes and mounting locations, and most of all...... we are looking for bass trapping ideas that look like architectural elements.


This is a 27' x 31' room.

It will have a ceiling mounted projector and roughly a 15' wide AT screen in 16:9. Any info about that screen wall would be most helpful.


Thanks,

Rob


----------



## pepar




> Quote:
> Originally Posted by *Rob Will* /forum/post/17716560
> 
> 
> Yes, as opposed to outright sarcasm like:
> 
> 
> "Everyone on this forum is so forthcoming with information"
> 
> 
> I'm just trying to get a basic understanding of some acoustical issues to convey to our architect. Fortunately, Ethan Winer has gone to a lot of effort to share his knowledge and posted some VERY informative articles on the net. I will be sure and tell the architect about RealTraps acoustic ceiling tile and other cost-effective products
> 
> 
> 
> 
> 
> 
> 
> .
> 
> 
> Aside from that, I am trying to get a feel for how much space we need behind the screen, approx speaker sizes and mounting locations, and most of all...... we are looking for bass trapping ideas that look like architectural elements.
> 
> 
> This is a 27' x 31' room.
> 
> It will have a ceiling mounted projector and roughly a 15' wide AT screen in 16:9. Any info about that screen wall would be most helpful.
> 
> 
> Thanks,
> 
> Rob



Respectfully, Rob, if you popped in with one question, many here could answer. But you seem to be looking for turnkey design services. Those on this thread that have that ability are pros who make a living at it.


You can either continue to do your own research, or you can become a customer of Ethan's or GIK or Terry Montlick and be told what to place where (and where to buy it in the case of Terry as he is *only*







an acoustician and not a vendor).


Jeff


----------



## Ethan Winer




> Quote:
> Originally Posted by *Rob Will* /forum/post/17712439
> 
> 
> How can you take a space with so much reverb that it is hard to understand speech and make it a high quality theater?



That's a large space, so the answer is a fair amount of absorption placed in various locations around the room. Where depends on many factors, such as the location of the seating and loudspeakers etc.


--Ethan


----------



## bpape

The point Rob was that if the room was 50x100, those times are more acceptable than if it's 10x15.


The room you're describing is not quite big enough for large space acoustics but pretty big for small space acoustics.


For a theater will full range music you'll need some broadband bass control and a reasonable amount of absorption around the space including reflections and the front wall to get it under control.


Behind an AT screen, the amount of space will depend on the speakers, their depth, etc. Broadband bass control can also be hidden behind the false wall if the entire wall is also AT.


Columns are an easy way to get broadband bass control in the room. You can also use sealed panel type absorbers concealed as wood paneling around the bottom of the room.


Can you at least give us an idea of how many seats will be in the space and what type they will be? What is the floor covering like? Is the ceiling hard I assume and not a drop tile design? There are just a ton of variables.


Bryan


----------



## Rob Will

Thanks guys!


A lot of people seem to assume that I'm not covering all the bases







.

The reality is that over the last two years, I have received specific product recommendations from Real Traps *and* GIK. Tomorrow, I am expecting a call from a major speaker manufacturer regarding speaker depth and specific product recommendations. A few months ago, Christie flew in some projector equipment for us to look at. IMHO and regardless of all this manufacturer support, I have not even touched the surface of "turn key" design - and don't intend to.


The reason that I ask a lot of questions and read EVERY Ethan Winer article I can find is that I want to be an informed consumer and be able to ask relevant questions of vendors and design professionals. To be a better consumer, I have purchased FuzzMeasure and am using my guitar amp with an external mic for analyzing a test tone. I'm just getting started but so far, this acoustics stuff looks like a LOT of fun! I even signed up for an SAE Online course (surround sound and auditory environment). I hope it is a good class.


I figure that a public forum is for the open exchange of ideas and information. The Yellow Pages is for seeking work.


When the time comes to recommend a vendor. I'll probably remember the really smart ones who taught me the basics and helped our theater project be the best it could be







.


Hey Ethan, you will think this is funny - I've been weighing samples of insulation board from construction sites to get the density - look what you started!


Thanks all for the info,

Rob


----------



## Techlord




> Quote:
> Originally Posted by *bpape* /forum/post/17720944
> 
> 
> The point Rob was that if the room was 50x100, those times are more acceptable than if it's 10x15.
> 
> 
> The room you're describing is not quite big enough for large space acoustics but pretty big for small space acoustics.
> 
> 
> For a theater will full range music you'll need some broadband bass control and a reasonable amount of absorption around the space including reflections and the front wall to get it under control.
> 
> 
> Behind an AT screen, the amount of space will depend on the speakers, their depth, etc. Broadband bass control can also be hidden behind the false wall if the entire wall is also AT.
> 
> 
> Columns are an easy way to get broadband bass control in the room. You can also use sealed panel type absorbers concealed as wood paneling around the bottom of the room.
> 
> 
> Can you at least give us an idea of how many seats will be in the space and what type they will be? What is the floor covering like? Is the ceiling hard I assume and not a drop tile design? There are just a ton of variables.
> 
> 
> Bryan



I have heard and understand a lot about absorbing panels, I only have bass coming from my subwoofer, why would I need bass absorbers? My sub is truly non-directional, as in I could not tell you where it was in the room if I didn't know where it was.


----------



## erkq




> Quote:
> Originally Posted by *Techlord* /forum/post/17722374
> 
> 
> I have heard and understand a lot about absorbing panels, I only have bass coming from my subwoofer, why would I need bass absorbers? My sub is truly non-directional, as in I could not tell you where it was in the room if I didn't know where it was.



To cut reflections resulting in standing waves and response nodes.


----------



## Techlord




> Quote:
> Originally Posted by *erkq* /forum/post/17722462
> 
> 
> To cut reflections resulting in standing waves and response nodes.



Come to think of it from time to time my sub does rattle the plates in my kitchen, I'll probably buy some bass tone tubes. Will bass absorbers cut down on vibrations in the room?


----------



## Dennis Erskine

Rob...the course may prove interesting and perhaps confusing without understanding of some the fundamentals. I'd suggest you purchase Floyd Toole's book "Sound Reproduction".


----------



## Terry Montlick




> Quote:
> Originally Posted by *Rob Will* /forum/post/17712439
> 
> 
> The proposed space is about 26' wide x 31' deep and has a 3-faceted vaulted ceiling 16' high.
> 
> 
> ...
> 
> 
> My question would be: How can you take a space with so much reverb that it is hard to understand speech and make it a high quality theater? How can 1.5 second reverb times EVER be a good thing?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks,
> 
> Rob



You add a lot of absorption. A space that size should have a reverberation time of under about 0.4 seconds in order to be a high quality movie theater.


Commercial cinemas have their walls lined with acoustically absorbing material. If this isn't possible, more creative solution may be used -- such as hanging a lot of large absorptive acoustical clouds or baffles. I once did a design (for a large residential space) which had fifteen of these, each 4x8 feet!


- Terry


----------



## bpape

Broadband bass control is there to:


- Help with specific bass response issues

- Help extend the bass response by eliminating cancellations

- Maximize intelligibility and tightness by getting the decay time into the proper range.


Bryan


----------



## Terry Montlick

One more note on acoustic treatment. For a reverberant, acoustically hostile environment (such as a typical classroom), research has shown that early reflections actually improve speech intelligibility. So a couple of acoustic panels (either absorptive or diffusive) at early reflection points should _not necessarily_ be your first course of action.


- Terry


----------



## giomania




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17723655
> 
> 
> You add a lot of absorption. A space that size should have a reverberation time of under about 0.4 seconds in order to be a high quality movie theater.
> 
> 
> Commercial cinemas have their walls lined with acoustically absorbing material. If this isn't possible, more creative solution may be used -- such as hanging a lot of large absorptive acoustical clouds or baffles. I once did a design (for a large residential space) which had fifteen of these, each 4x8 feet!
> 
> 
> - Terry



Terry,


Since I will be measuring my room to see what else I might need to add, what should the reverberation time in my ~21' x 27' room?


Thanks.


Mark


----------



## yacht422




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/17724211
> 
> 
> One more note on acoustic treatment. For a reverberant, acoustically hostile environment (such as a typical classroom), research has shown that early reflections actually improve speech intelligibility. So a couple of acoustic panels (either absorptive or diffusive) at early reflection points should _not necessarily_ be your first course of action.
> 
> 
> - Terry



'classroom' as opposed to the typical 16 X 23 h/t? are early reflections not ALWAYS a "bad" thing??

for the diy in this thread, there are some things we ( I ) have taken as an absolute, among those things, reflection points. short of an rta intervention, how are we to know whether _to do or not to do_?(could experiment i guess - panels up - - - panels down - - panels half size etc, ad nauseum







)

walt


----------



## Digity8

I've used the mirror trick to find out the best place for my ATS acoustic panels, it seems its pretty close to the speaker itself, is that normal?


----------



## nathan_h




> Quote:
> Originally Posted by *Digity8* /forum/post/17744170
> 
> 
> I've used the mirror trick to find out the best place for my ATS acoustic panels, it seems its pretty close to the speaker itself, is that normal?



Depends on your room. But it is 100 percent possible.


----------



## bpape

Just remember that you have a reflection point/area for each speaker to each seat on each wall. So, 3 speakers up front, 4 seats, 12 points on each wall for example.


Bryan


----------



## pepar

And then look up and down and, the direction that is commonly missed, to the rear. Absorbing the 12ms delayed reflection from the sound that goes the six feet past me to the rear wall and then the same six feet back made the most difference in my room.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17754664
> 
> 
> Absorbing the 12ms delayed reflection from the sound that goes the six feet past me to the rear wall and then the same six feet back made the most difference in my room.



Yes, a lot of people overlook the difference between first reflections and early reflections. A wall closer than ten feet behind you gives early reflections if left untreated.


--Ethan


----------



## yacht422




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17756732
> 
> 
> Yes, a lot of people overlook the difference between first reflections and early reflections. A wall closer than ten feet behind you gives early reflections if left untreated.
> 
> 
> --Ethan



when dealing with first and second reflections, is there a proper size wall panel for each? what might be considered too large?

walt


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/17771691
> 
> 
> when dealing with first and second reflections, is there a proper size wall panel for each? what might be considered too large?
> 
> walt



It's all about the angles; the angles determine the correct size for *first* reflection point absorbers. (I don't think I've heard or anybody treating the second reflection points.) People talk about the mirror trick, but I prefer to think of pool shots. Angle of incidence equals angle of reflection. In any case, for each surface an analysis should be done projecting a line from _each_ speaker to the surface and on to _each_ listener. The points on the wall where these lines bounce define the size of the absorber.


----------



## glaufman




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17756732
> 
> 
> Yes, a lot of people overlook the difference between first reflections and early reflections. A wall closer than ten feet behind you gives early reflections if left untreated.
> 
> 
> --Ethan



Yes, sometimes the terms get used interchangeably... perhaps you could give a quick refresher on the differences and their implications for the more confused among us...


----------



## Weasel9992




> Quote:
> Originally Posted by *yacht422* /forum/post/17771691
> 
> 
> when dealing with first and second reflections, is there a proper size wall panel for each? what might be considered too large?
> 
> walt



Like Pepar said, there are a bunch of variables which lead to tons of options. Sometimes a 2'x2' panel is enough, but I'd say a 2'x4' panel is more reasonable as a starting place about 90% of the time.


Frank


----------



## Ethan Winer




> Quote:
> Originally Posted by *yacht422* /forum/post/17771691
> 
> 
> when dealing with first and second reflections, is there a proper size wall panel for each? what might be considered too large?



Too large is not likely to be a problem, but too small is. As pepar said, it's not a point, but an area. And the size of the area directly depends on how far you are from the speakers and how far the speakers are from the walls. The farther away, the larger the area you need to treat. In a close-up situation a 2x2 foot panel could be enough. Once you're 10 to 12 feet away or farther, even 4x4 feet is not too large.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *glaufman* /forum/post/17773136
> 
> 
> Yes, sometimes the terms get used interchangeably... perhaps you could give a quick refresher on the differences and their implications for the more confused among us...



A reflection is considered "early" if it arrives at your ears within about 20 milliseconds of the direct sound. Where the reflection comes from, or how many bounces it took to get to your ears, is irrelevant. All that matters is the time delay. A "first" reflection is literally that. A reflection that arrives at your ears on a single bounce, before other bounces.


--Ethan


----------



## glaufman

Thank you!


----------



## Dennis Erskine

Early reflections have two components ... time and intensity (loudness). A second dimension to "loudness" would be the delta between the "loudest" of the early reflections and the softest of those reflections as compared to the direct sound. The frequency at which that will occur will change based upon the primary (direct) distance assuming you keep the same delay (say 20ms) in the ITDG. As the primary distance increases, the degrees off axis from the speakers will also change. Taken with the quality of the off axis response at the seating locations will then begin to suggest a strategy for treatment (diffusive, absorptive, etc.)


----------



## Ethan Winer




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17780724
> 
> 
> Early reflections have two components ... time and intensity (loudness).



Good point Dennis. If early reflections are at least 15 dB below the direct sound, the resulting comb filter peaks and nulls are more tolerable than when they're only 5 dB reduced.


--Ethan


----------



## glaufman




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17780724
> 
> 
> Early reflections have two components ... time and intensity (loudness). A second dimension to "loudness" would be the delta between the "loudest" of the early reflections and the softest of those reflections as compared to the direct sound. The frequency at which that will occur will change based upon the primary (direct) distance assuming you keep the same delay (say 20ms) in the ITDG. As the primary distance increases, the degrees off axis from the speakers will also change. Taken with the quality of the off axis response at the seating locations will then begin to suggest a strategy for treatment (diffusive, absorptive, etc.)



Umm...err... ITDG?


----------



## avare




> Quote:
> Originally Posted by *glaufman* /forum/post/17782684
> 
> 
> Umm...err... ITDG?



Initial Time Delay Gap


Merry Christmas, with no delay,

Andre


----------



## glaufman

Geez, we have an acronym for everything, don't we!


----------



## Techlord

I have my work cut out for me, my THX speaker system has the LCR speakers tweeters angled 4.7 degrees away from the sweetspot while my center speaker has the tweeter angle 4.7 degrees up. I will probably angle the center speaker down rather than up since it's above the listening position, as for angling my LR speakers in is out of the question! I have already tried that and seem to loose the stereo imagining completely, like there out of phase. I think some absorbers in towards the corners of the room will be needed.


Question: once I calibrate all my speakers for the listening possition(sweetspot), am I supposed to find the peak loud areas with my SLPM in the room and treat those areas with absorbers?


Happy Christmas Eve,

Tecklord.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Techlord* /forum/post/17783261
> 
> 
> am I supposed to find the peak loud areas with my SLPM in the room and treat those areas with absorbers?



The first place for bass traps is in the corners. Understand that rectangle rooms have 12 corners, not just four. After the corners are treated, the next place is the rear wall behind the listening position. If that wall is closer than ten feet behind you, the traps need to absorb mids and highs as well as bass.


--Ethan


----------



## Techlord




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17785624
> 
> 
> The first place for bass traps is in the corners. Understand that rectangle rooms have 12 corners, not just four. After the corners are treated, the next place is the rear wall behind the listening position. If that wall is closer than ten feet behind you, the traps need to absorb mids and highs as well as bass.
> 
> 
> --Ethan



I have a foot behind me to the rear wall. I have noticed big difference in surround sound quality and placement of sounds by leaning my head forward a foot, the surround sound effect is more easily heard. I have moved my couch forward 1ft., what a big difference it makes! That's the most effective thing I have even done with speaker positioning that made the most difference! Before the surround sound sounded diffused and reflected!


----------



## Goshwin




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17785624
> 
> 
> The first place for bass traps is in the corners. Understand that rectangle rooms have 12 corners, not just four. After the corners are treated, the next place is the rear wall behind the listening position. If that wall is closer than ten feet behind you, the traps need to absorb mids and highs as well as bass.
> 
> 
> --Ethan



So less then 10 ft means no sound diffusers back there?

I was thinking of putting a line of diffusers across the wall at 3/4 level.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Goshwin* /forum/post/17787519
> 
> 
> So less then 10 ft means no sound diffusers back there?



Not necessarily. My point is that when the rear wall is closer than about ten feet, the reflections at mid and high frequencies are considered "early" and should be addressed. I've used diffusors as close as a few feet behind with good results.


--Ethan


----------



## kevinzoe




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17793845
> 
> 
> Not necessarily. My point is that when the rear wall is closer than about ten feet, the reflections at mid and high frequencies are considered "early" and should be addressed. I've used diffusors as close as a few feet behind with good results.
> 
> 
> --Ethan



~~~~~~~~~~~~~~~~~~~~~~

Goshwin wrote: "So less then 10 ft means no sound diffusers back there?

I was thinking of putting a line of diffusers across the wall at 3/4 level. "


Goshwin, if you're planning on putting diffusion on the back wall behind the listening chair, then ponder the following considerations:


1.) LOW FREQUENCY OPERATING RANGE - as diffusers need to handle long wavelengths and should work down to your room's Schroeder or Transition frequency (typcially 300-500Hz), pick a design with the deepest cell/well depth as you can find or build yourself, with the limitation being distance from diffuser to listening chair (see point 2. below).


2.) DISTANCE BETWEEN BACK WALL & LISTENING CHAIR - should be 3 wavelengths of the lowest frequency that the diffuser will perform well at, so that the sound coalesceses before it reaches your ears and troublesome lobbing isn't heard. If you're considering the more popular QRD- or Skyline-types of diffusers, then a conservative calculation of the lowest frequency wavelength will be to multiply the deepest cell depth in inches by 2 to get the entire wavelength of the lowest freq that the diffuser will work well at and then express it in feet by dividing it by 12 and then divide it into the speed of sound of 1130. For example, a Skyline of max cell depth of 7.5" will perform well down to 904Hz [ 1130/((7.5*2)/12) ]. The diffuser will continue to perform to lower frequencies but with diminishing ability. Now calculate 3 wavelengths of 904Hz as follows: 1130/904 * 12 * 3 = 45inches. So you'd need to sit at least 45inches away from the rear wall with a diffuser of max depth equal to 7.5 inches.


3.) DIFFUSER PLACEMENT - be sure they are centered at ear level so 3/4 height may/may not fit the bill depending on seating height and of course your height! Also it should cover 2ft below and above your ear level so a minimum dimension of 4ft.


4.) WALL COVERAGE AREA - Prof Trevor Cox a diffusion expert, told me that some general diffusion principles exist, most relevant is the less periodicity the more diffuse the scattering. Dr Floyd Toole concurs saying "these designs get better as they get larger." So, to improve scattering efficiency over your desired wall area, choose a Skyline diffuser with the largest prime number or QRD diffuser with the largest number of wells to cover the desired area, and in both cases a max cell/well depth as calculated above. So it's better to have one large diffuser than several smaller ones put together. For a polyfuser pick one with at least a 12" radius however when combined with other polyfusers it loses its ability to diffuse low frequencies, so space them apart, change angles, and change their radius depths too if possible.


Hope these other considerations are useful and helpful.


----------



## yacht422

re: item #2

how does one treat a two row room, when the rear row is 14" from the wall? I have no flexibility regarding the chair(s) location. "they gotta be there".

walt


----------



## Kal Rubinson




> Quote:
> Originally Posted by *yacht422* /forum/post/17800688
> 
> 
> re: item #2
> 
> how does one treat a two row room, when the rear row is 14" from the wall? I have no flexibility regarding the chair(s) location. "they gotta be there".
> 
> walt



Absorbtion, not diffusion.


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/17800688
> 
> 
> re: item #2
> 
> how does one treat a two row room, when the rear row is 14" from the wall? I have no flexibility regarding the chair(s) location. "they gotta be there".
> 
> walt



Yacht422 - with only 14" behind the last row you really only have 1 viable option which is for broadband absorption in the centre of the back wall. As a 14" clearance is not much room to play with, I'd suggest you consider the type of broadband bass trap called "membrane or diaphragmatic" which works on the principle of absorbing sound most efficiently when the sound wave's pressure is maximized, which is right at the point on impact with the wall - so diaphragmatic absorption traps hang on the wall and are usually thin enough to work with your 14" limitation. The other absorption option most seem to select is a "resistive" broadband bass trap which should be a minimum of 4" thick with the thicker the better. However, the resistive traps works best when the sound air partical speed is maximized (not its pressure) which is one-quarter of the wavelength's distance out from the wall. So a 100Hz has a wavelength of 11.3ft so one-quarter equals 34", clearly beyond your 14" distance. Your 14" distance equates to about one-quarter of a 250Hz frequency so the resistive trap type may still be acceptable and is typically less costly than the thinner diaphragmatic type.


You might consider diffusion on either side of the broadband absorption if the distance between it and the rear seats warrants it.


----------



## Weasel9992




> Quote:
> Originally Posted by *kevinzoe* /forum/post/17800929
> 
> 
> You might consider diffusion on either side of the broadband absorption if the distance between it and the rear seats warrants it.



Good point Kevin...diffusion isn't totally precluded. It just can't be placed instead of absorption.


Frank


----------



## yacht422

kal: kevin: weasel9992: many thanks for the insights and the defining math.

i am a diy guy - will fab 4" thick absorbers for the rear wall(currently 2")[ two - 2' X 4' X 2" covered and framed] soooo much to learn, so little time.

( we used to race sailboats on the chesapeake bay - and i thought THAT was complicated! HAH!)

walt


----------



## Weasel9992




> Quote:
> Originally Posted by *yacht422* /forum/post/17817155
> 
> 
> i am a diy guy - will fab 4" thick absorbers for the rear wall(currently 2")[ two - 2' X 4' X 2" covered and framed]



Cool...that'll work a lot better than 2".


Frank


----------



## yacht422




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17821219
> 
> 
> Cool...that'll work a lot better than 2".
> 
> 
> Frank



thx, and a happy new year!









walt


----------



## captainkidd

Hello all! I am building/setting up a dedicated theater room and looking for some help in regards to placement of 6 newly constructed acoustic panels. The panels are 2'X4' constructed with Owens Corning 703 2" fiberglass insulation and will stand about 2.5" off the walls.


I better start with a rundown of my setup. The room is a big rectangle but only about 40% of it is the 'theater'. The rectangle is 30'X20'X16' high and I am using the first 12' for my theater. The 125" projector screen is placed on the end of one long wall with seating positioned along the opposite wall, about 17' from the screen.


My Receiver is a Denon AVR 590 and speakers are a 5.1 system of Klipsch WF-35 towers and matching center with smaller surrounds and an Energy 200 watt, 8" sub. The speakers are placed such that the two on the left side are out in space since there is no dividing wall on the left side to separate the theater area from the gaming area.


The room is a converted RV garage which is why it is so tall. The long walls (front and rear) are concrete block, the right hand (near) wall is sheet rock and the left hand (far) wall, which is about 18' away from the left side of the 'theater' area is a giant garage door. The floor is VCT tile over concrete.


The sound in the room is extremely lively with a lot of echo and I am having a hard time hearing dialogue in movies. I think the bass sound effects might be drowning out the dialogue because when I listen to music that doesn't have much bass the words are crisp and clear.


So, on to my question. I have built 6 of these,

http://www.instructables.com/id/Make...ing-studio-or/ 


And am looking for advice on where to install them. I am not sure weather to orient them horizontally or vertically and weather to use them in corners as bass traps, at early reflection points on the near wall or on the rear wall. There is not enough room between my screen and the right hand wall/floor to position one of them in there at a 45 degree angle so that option is out.


I wish I could draw the room to help show the layout but don't know how. Hopefully my description is good enough. So, any suggestions?


----------



## yacht422

Can you build a room in a room? you can make a manageable rectangle out of a few studs and some drywall -all diy - and then there will be a room you can easily 'sound' treat.









Given the cubes of the _existing_ space, you'll need _way_ more amp power and _far_ larger sub(s) and lots of sound panels to generate satisfying sound ( as opposed to noise







) - and of course, carpeting.

there are industry men that monitor this site and will provide useful insights - but - trying to treat a room of this size is almost industrial in scope, imho.

good luck

walt


----------



## Pete

There seems to be a multitude of manufactures that are selling acoustic treatments. If there were a CW short list of the most competent and comprehensive vendors -- specifically with HT in mind -- who would be on it?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Pete* /forum/post/17834981
> 
> 
> There seems to be a multitude of manufactures that are selling acoustic treatments. If there were a CW short list of the most competent and comprehensive vendors -- specifically with HT in mind -- who would be on it?



Most of them are mentioned and wrung out here in this forum. For a starting list, take a look at the links provided by Rives Audio: http://www.rivesaudio.com/resources/links/frame.html


----------



## WWWestonC

Although I'm constructing my first and a low budget theater, you guys have me convinced to take the time and try and incorporate some acoustical treatments.


Where I'm at now, the walls/soffits are mudded and taped, the stage and cabinets are built, and the riser will be built this week.


I went to Wal-mart and picked up some black fabric (12 yards of it) and am planning to spray with the 3M fire retardant. I'm going to call HVAC contractors this week to try to secure some Linacoustic.


My question is can someone direct me to a good thread with pictures on the install of a similar build. I'm hoping for a thread with pictures detailing the install of the fabric / acoustical treatments. I was planning on painting the wall red above ear level all the way around.


Appreciate any help you can provide.


Here's a link to my build thread which has some (weak) pictures. I can get more if needed.

http://www.avsforum.com/avs-vb/showthread.php?t=1205353


----------



## Kemet

Can OC Foamular 150 panels be used as acoustical panels to absorb early reflection frequencies behind a speaker or would they just be wasting space?


----------



## MikeWojcik

I know I've read in this forum that speakers should not be placed behind Anchorage since it is less transparent than , say 701. Would a subwoofer be impacted as well?


Thanks!


----------



## MarkMac




> Quote:
> Originally Posted by *Kemet* /forum/post/17836577
> 
> 
> Can OC Foamular 150 panels be used as acoustical panels to absorb early reflection frequencies behind a speaker or would they just be wasting space?



I don't know if there is any acoustic data available for this product, but I would _guess_ that it would be a very poor choice for an absorption material. This a rigid foam insulation product, and I would expect that if would be very reflective...(but I don't have any data to back that up).


----------



## Dennis Erskine

This is a closed cell foam product and would not provide the absorption benefit you're looking for.


----------



## Weasel9992




> Quote:
> Originally Posted by *Pete* /forum/post/17834981
> 
> 
> There seems to be a multitude of manufactures that are selling acoustic treatments. If there were a CW short list of the most competent and comprehensive vendors -- specifically with HT in mind -- who would be on it?



Budget, the amount of help you need and how you want to install things all factor into who you use.


Frank


----------



## pepar

Noob question, but I want to be sure ...


Will a simple waterfall measurement at my primary listening position give me all the data I need to determine whether the reduction in absorption and addition of diffusion that I *think* I need is .. really .. needed.










TIA!


Jeff


----------



## CJO




> Quote:
> Originally Posted by *MikeWojcik* /forum/post/17837318
> 
> 
> I know I've read in this forum that speakers should not be placed behind Anchorage since it is less transparent than , say 701. Would a subwoofer be impacted as well?
> 
> 
> Thanks!



I'm no professional, but I wouldn't think that there would be an issue with bass. The Anchorage reflects higher freqencies significantly more than 701, which is why it isn't suggested for full-range speakers.


CJ


----------



## HT1

I have a multi-purpose room that is half bar and home theater. We had our first gathering over the holidays mainly in the bar half of the room where I noticed that conversations where really loud. I'm guessing due to room echo since the bar half is tile floor, wood bar and the entire room is drywall. My question is how can I tame some of this echo? I do not have any fancy measuring device and wouldn't know what to with them if I did. But I would like to build some panels to hang on the walls just to do some low tech experiments to see if I can tell a difference by ear. From what I have read I'm guessing I need sound absorption material? My room dimensions and layout are all in my signature thread. This is has been my first attempt at this bar/ht thing so I'm learning thru trial and error and I go. Any suggestions would be appretiated.


----------



## forestmoonstudio

I am doing a HT from an exisiting room. Walls are drywall. My wife wants hardwood floors. We are going to get a big area rug that will take up alot of the floor space. The room is 16'x14'. The 106'' screen will be on front wall. The back wall is a Bay window that will have block out curtains covering it. One side wall will have a door and a column. The other side wall will have 3 columns built onto it. I was thinking of building panels for the walls out of covered OC 703.

Now getting to my real question. Will putting framed movie posters on the acoustic panels basically void out the panels?


Would the pink or blue insulation foam work good for panels instead of the fiberglass?


----------



## MikeWojcik

Thanks CJ


that is what i was thinking (although without the "qualifications" to do so).


Can any experts confirm? Question is whether subwoofer frequencies are sufficiently less impacted by the use of GOM Anchorage fabric in front to allow that without sound quality impacts...


Thanks

Mike



> Quote:
> Originally Posted by *CJO* /forum/post/17845327
> 
> 
> I'm no professional, but I wouldn't think that there would be an issue with bass. The Anchorage reflects higher freqencies significantly more than 701, which is why it isn't suggested for full-range speakers.
> 
> 
> CJ


----------



## Kemet




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/17844510
> 
> 
> This is a closed cell foam product and would not provide the absorption benefit you're looking for.




Thank you very much for the confirmation on Foamular 150, I was hopeful it might but didn't expect it to provide much benefits.


----------



## Bass Slut

i have an open unfinished poured concrete basement, with some carpet on the floor for office space, wife all upstairs


i have 7.6' x 22.6' x 38.6'

which gives me resonances @ 75hz x 50hz x 14.6hz


i used 3 old speakers from the eighties with 2.0 cubic feet of volume each.

i blanked off the holes & made Helmholtz resonators to spec, one for each dimension


while playing music, i used rolled cardboard & pvc for telescopic ports

it all seemed to tune in quite audibly

then i made the tune sound right by padding the ring time efficiency with rags


the 75hz box got a piece of wood over a 4" open hole, to create an adjustable valve, tuned right in, took 1.6 rags

the half moon finished port appeared close to calc, 2.8"

very audible, to the middle of the basement


the 50hz box, i suspect may be padding the room & maybe the peak in my band pass

tunes right in with 2.0 cu' box, 3.75" id port, 3.6" long

about 1/8" longer than calc, probably stuff still in speaker box reduced actual volume

after listening in the middle of better sounding basement, i added just another 15% of a rag to the 50 hz box

very audible, to the middle of the basement


the 14.6hz box i used a 2.5" ID port, 14.5" long

my third speaker cabinet from the eighties was only 1.77 cu'

& this port tunes 1/4" shorter than calc

i only have 15% of a rag in this box for ring time

if you stuff in one too many rag, it goes to mud instantly

this box does more to clean up the sound than anything

it doesn't appear to eliminate allot of obvious sound, but it's a necessity


i located all three resonators @ the stacked subs for the most energy

which is 6' from the computer/main listening area

i have two stacked 6.6 cu' band pass boxes stacked in the corner, 45 degrees

one port firing @ corner ceiling, one port @ corner floor


placement seemed to be critical to get the most out of them

almost a phasing issue the way they sound good

i tried various arrangements of the resonators around the sub & the best seems to be:

75hz box on top of the subs firing @ ceiling

50hz box on floor, straight out from the back of the 45 degree subs, where it's in phase w something


the 14.6hz box sounds good pointed @ my head

it would make a nice hat

i didn't think it would help much, but it's octaves of 30 45 60

it really cleans up the sound & it's root freq is narrow & fatiguing

it's also on the floor, the furthest out, next to the 50, pointing up


it sounds really really good

it seems like it helped the nulls i experience in the middle of the basement just as much

the ringing is still serious @ the rear corner, next to the furnace


i could listen for days now


i wonder if there's helmholtz dampening effects over a range of freqs & corner loaded calcs, graphs, plots, models over room space??


it sounds good & everything, but i haven't seen much info on efficiency anywhere


would i have a better effect over the entire basement if i used a 5' long 4" diameter port, instead of a 1' long 2.5" diameter port, on the 14.6hz box ??


would i have a better effect over the entire basement if i used a larger box, how much db ??


great forum


----------



## Bass Slut

oh well, so much for the longest first post evar










looks like i made a math error on room width & should be targeting 25hz, not 50

for anyone that could read that


which means 25hz & 125 hz aren't dampened


maybe i'll get out & buy some 4" pvc today


i highly recommend helmholtz boxes for concrete rooms


----------



## Bass Slut

i have an acoustic consulting friend i called today & we spoke @ length

his thoughts were the 38 foot long section of the basement was irrelevant

but the width of the room would be ringing an octave over it's width @ 50hz loud

he said i should keep the 50 hz box because it would be 6db more influential than the 25hz box & there' more music there


it turns out after remeasuring & claculating that my 14.6hz box with it's 1 inch longer port & uncalculated innards volume was actually tuning to 25 hz

that's why it was so obvious to tune with the 50 hz box next to it

home on all three port adjustments is audible to the millimeter

concrete room is nice


to sum it up:

3 helmholtz resonators @ 75hz, 50hz, 25hz placed @ sub corner

75 hz matches floor to ceiling resonance

25 hz matches the width of the room

50 hz offers more help with width of room, octave up

best sounding sub i've evar had


this forum has been a gold mine & i'm sure there's lots more to learn


----------



## maxfli

Hi all,


I am ready to add treatment to my converted 2-car garage HT room. One of the challenges I have is in the corners for adding bass traps. Each corner has a 9" x 9" pillar from floor to ceiling that restricts the area for using certain products.


I've decided on cutting product to fit the area. I understand that foam products though maybe easier to work with aren't good for bass-trapping. So, which of these products would be easier to work with for cutting into sections and fitting into a corner: OC 703, Johns Manville IS 300 or 600, or Certainteed OEM 300 or 600?


Secondly, if 3" of OEM 600 is 64% absorptive at 125 Hz, does it hold that 2 sheets of 3" OEM 600 would be ~ 128% aborptive?


Thanks,

Max


----------



## kevinzoe

Max - regarding your 2nd question, I don't think it's as simple as just doubling the absorption effectiveness for the given 125Hz frequency. (After all, what does 128% mean?!)


At the very best I would think that the 1st panel being 64% effective (whatever that truly means) lets 36% through it so adding a 2nd panel (behind the 1st panel) will absorb 64% of the 36% that it 'sees' or 23%. So I think that the very best you could hope for is 87% (64%+23%), but that is likely stretching things as there will be sound waves that reflect off of it at higher frequencies and propogation loss just through the air as well . . . The thicker you can make the traps the better off it will perform down to lower frequencies.


For what it's worth, my bass traps range in thickness from 12" to 35.5" and have a 6.5" air space behind them all which roughtly equates to a quarter wavelength of 500Hz which is an estimated transition zone (or Shroeder frequency) for my sized room. You might want to calculate what the 1st, 2nd, and 3rd modes are of the garage's dimensions (i.e. length, width, and height) and base the trap's thickness around at least the 3rd mode of each dimension and preferable the 2nd mode too - the first mode of the longest dimension will likely require too thick a fibreglass filled trap to be practical. So if your length is say 25feet, then the 1st, 2nd and 3rd nodes are at 22.6Hz, 45.2Hz and 67.8Hz. (Calculation: speed of sound 1130 divided by 2 times the length of 25ft = 22.6Hz) So, building a trap to deal with the length's 3rd mode of 67.8Hz requires that the bass trap extend out from the wall to a thickness equal to one-quarter of the 67.8Hz wavelength which is 50" !! (Calculation: 1130/67.8*12=200"; 0.25*200=50") It might be more practical to use these calculation for the smaller two dimensions (width and height) and use a parametric eq to deal with remaining bass mode peaks.


If you're building 'resistive-type' bass traps filled with some kind of fibreglass, then remember that they work best when there is an air space behind them, in other words you might consider leaving the 9" airspace to accommodate your pipes. You can always put the bass traps in the opposite walls corners closer to the wall (i.e. smaller air space between wall and edge of trap) as a mix of things often helps to balance things out.


Good luck.


----------



## maxfli

Thanks for your response Kevinzoe. Your explanation makes alot of sense to me. I had always intended to 3X or 4X the 3 inches of product to get closer to a 100% absorption. I like the idea of placing the absorbers away from the wall to increase the rate.


The area where these will go is on a stage that is only about 4' deep at the corner. I'm going to trade out my SVS PB13 subs for their PC 13 cylindar subs to allow for treatment materials. The PB13 are great subs, but are beasts and consume about 2 feet of the 4 feet of stage, the pillars another 9", leaving little or no room for treatment. The PC13 have a much smaller form factor and are a better choice for my size room (20 L x 16 W x 9 H)


I will also look at the calculations as you've suggested, but may have to sacrifice some treatment size to keep the asthetics of the room. The room was built with visual appeal in mind. I'm just now getting to acoustic treatments and plan to treat as much as possible, but may go to a SVS sub equalizer if I don't have room to do the correct size of treatment.


I still am interested in knowing which of these materials is easier for cutting and shaping for the space I have.


Thanks again,

Max


----------



## bob53

Hi everyone,


I was hoping to solicit some help re: the appropriate acoustical treatments for my 2-channel / HT environment in my basement family room.

*The room:*

The room is irregular in shape (see pics below) but the main component is ~ 15 x 20 x 8.5 (ft). The room is open in the rear to the staircase and the HT system is not centered with the space. A fireplace was removed from the room to provide the room in the "space / enclave / nook" behind the proposed AT screen.

*The systems:*

The front screen wall will be AT, composed of Seymour XD material and GOM for the surrounding framing. Behind this wall, the plan calls for the speakers (3 Triad gold monitors, stand mounted), HT sub (1-2 JL F112s), and 2-channel boundary woofers (Lyngdorf W210s x 2 ).

*The issues:*

My 2-channel system relies upon the Lyngdorf software/hardware - including the two boundary woofers. For those not familiar with the Lyngdorf Room Perfect system, the boundry woofers exploit the room by aiming their 4 10 inch speakers at the 2 corners to produce bass, mid-bass, and midrange (the boundary woofers are, by design, digitally crossed over at 300-400 Hz!!!) while retaining 95 dB sensitivity and consuming minimal power. The mains only need to handle frequencies beyond 300-400 Hz.

http://www.lyngdorf.com/index.php?op...d=27&Itemid=55 

http://www.lyngdorf.com/index.php?op...d=76&Itemid=43 

http://www.lyngdorf.com/downloads/pr...on_english.pdf 


So my concern is that traditional acoustic treatments behind the screen wall may negatively impact the performance of this non-traditional arrangement, as the woofers rely upon reflections where bass traps and absorbing materials are traditionally placed.

*Questions:*

1. Should any treatments be used along the front wall? The Triad speakers are not ported, neither is the JL F112, and I assume this may be of some benefit in this case re: reflections behind the screen wall.


2. Should I still treat first reflection points within the room? Is the right.

reflection point less important given the fact it is much further away vs. the right.


3. What can be done about the open staircase at the back wall? It occupies the entire back wall (no door to close, etc.)


While I understand the basics of acoustics and treatments, specific recommendations would be helpful as I am still quite unfamiliar with the finer points of acoustic theory as it relates to this discussion.


Here are drawings of the room, a perspective of the room from the rear, and a more detailed drawing of the proposed screen wall.





























Thank you in advance for the assistance,


Bob


----------



## bighoot

Quick question, the celing in my basement theater is approx 7ft. There is a 8" beam running accrost the room at the mid point, I have been wanting to remove the beam and replace with Steel I beam so the celing would be flush. Got to wondering if I where to drywall down tho the beam and then taper the celing from the beam to the floor joist( it would appear that the celing drops in the middle of the room and tapers back to the front and read walls) would be 8' over a 10ft span. Taking out the beam is going to be a PITA so I am looking for solutions. Saw this in a commercial theater not sure if it was for accoustics or something else. Ideas


----------



## yacht422




> Quote:
> Originally Posted by *pepar* /forum/post/17772171
> 
> 
> It's all about the angles; the angles determine the correct size for *first* reflection point absorbers. (I don't think I've heard or anybody treating the second reflection points.) People talk about the mirror trick, but I prefer to think of pool shots. Angle of incidence equals angle of reflection. In any case, for each surface an analysis should be done projecting a line from _each_ speaker to the surface and on to _each_ listener. The points on the wall where these lines bounce define the size of the absorber.



ARE THERE NO SIDE WALL SECOND REFLECTION POINTS?

IN OTHER WORDS, _TREATING THE FRONT OF THE ROOM SIDE WALLS_ (1st r/p) is all that is needed for SIDE WALLS?

FRONT AND REAR WALLS -DIFFERENT DISCUSSION, FOR NOW.

WALT


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/17870519
> 
> 
> ARE THERE NO SIDE WALL SECOND REFLECTION POINTS?
> 
> IN OTHER WORDS, _TREATING THE FRONT OF THE ROOM SIDE WALLS_ (1st r/p) is all that is needed for SIDE WALLS?
> 
> FRONT AND REAR WALLS -DIFFERENT DISCUSSION, FOR NOW.
> 
> WALT



Speaker to a wall to another wall to your ears? Yes, of course. I've just never heard of anyone treating for that though. Come to think of it, I've never even heard anyone refer to second reflection points. I'm sure the real acousticians here have a better answer, but my guess is that beyond the FIRST reflections, the next ones are more diffuse, more delayed and meld into the reverberant field.


Actually, I think front wall and rear wall *are* part of the same discussion if you want to improve your acoustics.


----------



## yacht422

Quote:

Originally Posted by *pepar* 
speaker to a wall to another wall to your ears? Yes, of course. I've just never heard of anyone treating for that though. Come to think of it, i've never even heard anyone refer to second reflection points. I'm sure the real acousticians here have a better answer, but my guess is that beyond the first reflections, the next ones are more diffuse, more delayed and meld into the reverberant field.


Actually, i think front wall and rear wall *are* part of the same discussion if you want to improve your acoustics.
yes! I have front and rear treatments, but not to the degree of your h/t. This is still a work in progress. The additional work i do follows the knowledge i gain from this thread.









attached is a pdf of the right wall showing the wall treatments walt

 

view of entry h:t.pdf 265.9296875k . file


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/17871738
> 
> 
> yes! I have front and rear treatments, but not to the degree of your h/t. This is still a work in progress. The additional work i do follows the knowledge i gain from this thread.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> attached is a pdf of the right wall showing the wall treatments walt



Wow, Walt, nicely done. WRT the surround - if it is a dipole or bipole, the absorber on which it is mounted is likely interfering with it providing envelopment. FWIW, I probably wouldn't have any treatment there unless it was needed to manage RT60.


Jeff


----------



## yacht422




> Quote:
> Originally Posted by *pepar* /forum/post/17872072
> 
> 
> Wow, Walt, nicely done. WRT the surround - if it is a dipole or bipole, the absorber on which it is mounted is likely interfering with it providing envelopment. FWIW, I probably wouldn't have any treatment there unless it was needed to manage RT60.
> 
> 
> Jeff



i can remove, just sits on the dipoles(2 cones face to front, one 6" into the room, two cones to the rear)

the problem i have been attempting to resolve is reflected in the chart attached.

[i use the anthem room correction software (ARC) which works along the same lines as audessy(sp).]

there is a major hump in the lf/rf as well as an over/under swing at the 500 to 2500 range in the dipoles. i had hoped that the wall treatments hanging on the di's would solve the 'di' problems - did not, but, i never took them down.

still looking for solutions to those issues

walt


----------



## johnbomb

Has anyone utilized drywall for bass trapping? I'm planning on installing 16" to 32" wide panels of drywall around the room with thicknesses alternating between 1/4", 1/2", and 5/8", backed with pink insulation.


By adding weight selectively to the panels, I hope to tune their resonances to those of the involved axial room modes above 80hz (I'm building a "double bass array" to counteract those below 80hz, as linked below).

http://www.avsforum.com/avs-vb/showthread.php?t=837744 


Thanks,

John


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/17870519
> 
> 
> ARE THERE NO SIDE WALL SECOND REFLECTION POINTS?
> 
> IN OTHER WORDS, _TREATING THE FRONT OF THE ROOM SIDE WALLS_ (1st r/p) is all that is needed for SIDE WALLS?
> 
> FRONT AND REAR WALLS -DIFFERENT DISCUSSION, FOR NOW.
> 
> WALT



******************************

Yacht422(a.k.a.Walt):

Regarding your question about treating second reflection points - I had this exact discussion with Dr Sean Olive over the phone recently and he said that 2nd reflection points would not likely require treatment due to several factors that reduce the specular intensity of a 2nd reflection. These factors that reduced the 2nd reflection 'loudness' level included propogation loss before and after the 1st boundary impact (1st reflection point), the impact of the 1st reflection point itself, and the reduced reflected energy if the 1st reflected point was an absorber or diffuser.


So to your point IF you're going to treat side wall or ceiling 1st reflection points, you can forget about treating 2nd reflection points (which is likely a good thing as they could be nasty to pin point without some kind of ray tracing system). I'd agree with Pepar in that reflections after the 1st reflection points become part of the indirect and reverberant sound field.


For music-only rooms (like what I have), treating 1st reflection points isn't really required (unless large slap echo exists between hard parallel surfaces) as Dr Floyd Toole points out in his latest book. The reflections actually add to the sense of listener envelopment and apparent sound source width and helps create a low "Inter Aural Cross-Correlation" which is a fancy scientific term that means that the left and right ears are hearing different things - a high IACC means the ears are hearing very similar or the same thing. Toole goes on to say that treating 1st reflection points is a good idea if you're a musician who is mastering their music or someone doing comparative stereo component evaluations (magazine reviewers?!).


Clear as mud?


----------



## yacht422




> Quote:
> Originally Posted by *kevinzoe* /forum/post/17874846
> 
> 
> ******************************
> 
> Yacht422(a.k.a.Walt):
> 
> Regarding your question about treating second reflection points - I had this exact discussion with Dr Sean Olive over the phone recently and he said that 2nd reflection points would not likely require treatment due to several factors that reduce the specular intensity of a 2nd reflection. These factors that reduced the 2nd reflection 'loudness' level included propogation loss before and after the 1st boundary impact (1st reflection point), the impact of the 1st reflection point itself, and the reduced reflected energy if the 1st reflected point was an absorber or diffuser.
> 
> 
> So to your point IF you're going to treat side wall or ceiling 1st reflection points, you can forget about treating 2nd reflection points (which is likely a good thing as they could be nasty to pin point without some kind of ray tracing system). I'd agree with Pepar in that reflections after the 1st reflection points become part of the indirect and reverberant sound field.
> 
> 
> For music-only rooms (like what I have), treating 1st reflection points isn't really required (unless large slap echo exists between hard parallel surfaces) as Dr Floyd Toole points out in his latest book. The reflections actually add to the sense of listener envelopment and apparent sound source width and helps create a low "Inter Aural Cross-Correlation" which is a fancy scientific term that means that the left and right ears are hearing different things - a high IACC means the ears are hearing very similar or the same thing. Toole goes on to say that treating 1st reflection points is a good idea if you're a musician who is mastering their music or someone doing comparative stereo component evaluations (magazine reviewers?!).
> 
> 
> Clear as mud?



but - - - it covers the ground!

Regrettably, my task is somewhat more complex than 'A' chair with all the audible firepower pointed at it.

I have 8 leather chairs and the Master Audio sound track coming from all sides.

I'm not complaining, just observing a fundamental difference in your and my needs.

I've read thru two _how to_ books, one by jim smith, the other by a reviewer, and both tomes concentrate on the single chair audiophile - not the 8 chair h/t.

so - - - i continue to read and post and slowly kind folks such as yourself offer guidance.

Thanks - and, any additional insights are appreciated.

walt


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/17874945
> 
> 
> but - - - it covers the ground!
> 
> Regrettably, my task is somewhat more complex than 'A' chair with all the audible firepower pointed at it.
> 
> I have 8 leather chairs and the Master Audio sound track coming from all sides.
> 
> I'm not complaining, just observing a fundamental difference in your and my needs.
> 
> I've read thru two _how to_ books, one by jim smith, the other by a reviewer, and both tomes concentrate on the single chair audiophile - not the 8 chair h/t.
> 
> so - - - i continue to read and post and slowly kind folks such as yourself offer guidance.
> 
> Thanks - and, any additional insights are appreciated.
> 
> walt



Walt - much of Dr Floyd Toole's latest book is dedicated to HomeTheatre so your multi-person requirements are addressed in it. I scimmed that section of course so I can only recommend you borrow/buy it.


----------



## yacht422




> Quote:
> Originally Posted by *kevinzoe* /forum/post/17874846
> 
> 
> ******************************
> 
> Yacht422(a.k.a.Walt):
> 
> Regarding your question about treating second reflection points - I had this exact discussion with Dr Sean Olive over the phone recently and he said that 2nd reflection points would not likely require treatment due to several factors that reduce the specular intensity of a 2nd reflection. These factors that reduced the 2nd reflection 'loudness' level included propogation loss before and after the 1st boundary impact (1st reflection point), the impact of the 1st reflection point itself, and the reduced reflected energy if the 1st reflected point was an absorber or diffuser.
> 
> 
> So to your point IF you're going to treat side wall or ceiling 1st reflection points, you can forget about treating 2nd reflection points (which is likely a good thing as they could be nasty to pin point without some kind of ray tracing system). I'd agree with Pepar in that reflections after the 1st reflection points become part of the indirect and reverberant sound field.
> 
> 
> For music-only rooms (like what I have), treating 1st reflection points isn't really required (unless large slap echo exists between hard parallel surfaces) as Dr Floyd Toole points out in his latest book. The reflections actually add to the sense of listener envelopment and apparent sound source width and helps create a low "Inter Aural Cross-Correlation" which is a fancy scientific term that means that the left and right ears are hearing different things - a high IACC means the ears are hearing very similar or the same thing.
> 
> 
> 
> Quote:
> Toole goes on to say that treating 1st reflection points is a good idea if you're a musician who is mastering their music or someone doing comparative stereo component evaluations (magazine reviewers?!).
> 
> 
> 
> 
> Clear as mud?
Click to expand...


am i to understand that treating first reflection points is _not necessarily_ necessary, in Dr. Tooles opinion, if we are treating a home theater? This certainly flies in the face of prevailing wisdom. Obviously, i'll need to read the book.

thx again

walt


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/17879910
> 
> 
> am i to understand that treating first reflection points is _not necessarily_ necessary, in Dr. Tooles opinion, if we are treating a home theater? This certainly flies in the face of prevailing wisdom. Obviously, i'll need to read the book.
> 
> thx again
> 
> walt



Walt, there are those that are saying early _lateral_ reflections are good. Ceiling, floor and rear wall are still treated. You're right about conventional wisdom, and I really have a hard time abandoning my thinking that the room should be neutralized as much as possible and the speakers should re-create the environment the artist created. New tech from companies like Audyssey and Dolby are aimed at expanding the front soundstage.


Jeff


----------



## yacht422




> Quote:
> Originally Posted by *pepar* /forum/post/17880027
> 
> 
> Walt, there are those that are saying early _lateral_ reflections are good. Ceiling, floor and rear wall are still treated. You're right about conventional wisdom, and I really have a hard time abandoning my thinking that the room should be neutralized as much as possible and the speakers should re-create the environment the artist created. New tech from companies like Audyssey and Dolby are aimed at expanding the front soundstage.
> 
> 
> Jeff



i had a series of conversations about a year(+) ago with the fine folks at ASC. They recommended i treat the front of the room first, to the tune of prox.$10,000.00. (just the front:rear to follow!)

Did not do so. Too many $$$! Interestingly enough, they were not concerned about first reflections, but, rather, controlling the lower notes, by using a pair of floor to ceiling half 18"dia and a half 24"dia tubes, matched on each of the front walls, prox where i have my wall treatments now.

(they wanted MY stuff to come down.)

they probably were correct, as i have a lingering spike in the 50H range that will not go away.

(full disclosure: i have Revel Ultima II across the front, plus two subs -there is a lot of bass potential there - that said, it should be controllable - and is not)

as i posted earlier, so much to learn, so little time.









walt


----------



## Weasel9992




> Quote:
> Originally Posted by *yacht422* /forum/post/17881733
> 
> 
> Interestingly enough, they were not concerned about first reflections, but, rather, controlling the lower notes...



I know what they're getting at there, but there's a balance to be struck. It's not one or the other...it's both.


How do we know what to do? With most rooms of a certain size and shape, used for a particular purpose, there are a number of basic steps you can take to solve a bunch of the issues as they tend to be the same or similar from room to room. From there you have to be more targeted based on the clients preferences, specific equipment employed and the particulars of room geometry, furniture placement and so on.


Frank


----------



## yacht422




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17881819
> 
> 
> I know what they're getting at there, but there's a balance to be struck. It's not one or the other...it's both.
> 
> 
> How do we know what to do? With most rooms of a certain size and shape, used for a particular purpose, there are a number of basic steps you can take to solve a bunch of the issues as they tend to be the same or similar from room to room.
> 
> 
> 
> Quote:
> From there you have to be more targeted based on the clients preferences, specific equipment employed and the particulars of room geometry, furniture placement and so on.
> 
> 
> 
> 
> Frank
Click to expand...




> Quote:
> So, at that point, is there a personal visit? I can provide room geometry, etc. but, short of an actual , shall i say RTA [if that is correct] how do we know we have done the best we can do? (poor choice of words, as i feel "best we - - - " etc portends mucho dollars .
> 
> The truth is, with 8 chairs, there is only an average _best sound_(i guess) and so i might be _tilting at windwheels_ in my attempt to go much past where i am now. I JUST DO NOT KNOW!!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Walt, in uncomfortably cold, rainy, florida.



Frank[/quote]


----------



## Weasel9992




> Quote:
> Originally Posted by *yacht422* /forum/post/17882501
> 
> 
> So, at that point, is there a personal visit? I can provide room geometry, etc. but, short of an actual , shall i say RTA [if that is correct] how do we know we have done the best we can do? (poor choice of words, as i feel "best we - - - " etc portends mucho dollars .
> 
> The truth is, with 8 chairs, there is only an average best sound(i guess) and so i might be tilting at windwheels in my attempt to go much past where i am now. I JUST DO NOT KNOW!!



That was a funny edit Walt.


Not usually from us or a company like ours. What you might want to do is call up somebody like Dennis Erskine and have him put together a comprehensive design. It'll cover a ton of bases...best way to go in just about every case if the budget is there. Even if it's not it's worth stretching for. Dennis (or someone like him) will make recommendations that will include a bunch of integrated solutions.


Frank


----------



## yacht422




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17882909
> 
> 
> That was a funny edit Walt.
> 
> 
> Not usually from us or a company like ours. What you might want to do is call up somebody like Dennis Erskine and have him put together a comprehensive design. It'll cover a ton of bases...best way to go in just about every case if the budget is there. Even if it's not it's worth stretching for. Dennis (or someone like him) will make recommendations that will include a bunch of integrated solutions.
> 
> 
> Frank



Thx for the recommendation. probably, at this point, the one best thing i can do.

Tonight is our wedding aniv, so i am taking the missus out to dinner,etc.

To all who offered insights, my thanks.

Have a great weekend (we MAY get snow here tomorrow - florida - snow!







)

Walt


----------



## Weasel9992




> Quote:
> Originally Posted by *yacht422* /forum/post/17882999
> 
> 
> Thx for the recommendation. probably, at this point, the one best thing i can do.
> 
> Tonight is our wedding aniv, so i am taking the missus out to dinner,etc.
> 
> To all who offered insights, my thanks.
> 
> Have a great weekend (we MAY get snow here tomorrow - florida - snow!
> 
> 
> 
> 
> 
> 
> 
> )
> 
> Walt



It's cold as heck here too. No snow though.










Frank


----------



## kevinzoe




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17883275
> 
> 
> It's cold as heck here too. No snow though.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Frank



Cold 'ya say . . .?! Why you southern types are a bunch of pansies - It's -20C with the windchill and -40C a couple of provences west of here, not that's cold!


Walt -before you contact Denise Erskine (or anyone else) I'd highly recommend you read Dr Floyd Toole's book, which if nothing else will educate you enough to better communicate with and understand Denise's recommendations.


I can't imagine that ASC's recommendation for just the front wall was going to cost US$10K - seems rather steep to me for a single wall. The front wall is the least important wall in my opinion and your Revel speakers are forward firing to boot so not sure what basis their reco's were based on.


Cheers,

kevin


----------



## forestmoonstudio




> Quote:
> Originally Posted by *forestmoonstudio* /forum/post/17848661
> 
> 
> I am doing a HT from an exisiting room. Walls are drywall. My wife wants hardwood floors. We are going to get a big area rug that will take up alot of the floor space. The room is 16'x14'. The 106'' screen will be on front wall. The back wall is a Bay window that will have block out curtains covering it. One side wall will have a door and a column. The other side wall will have 3 columns built onto it. I was thinking of building panels for the walls out of covered OC 703.
> 
> Now getting to my real question. Will putting framed movie posters on the acoustic panels basically void out the panels?
> 
> 
> Would the pink or blue insulation foam work good for panels instead of the fiberglass?



I am still wondering about framed movie posters on acoustic panels. Will the panels not work, because I would have a reflective surface on them?


----------



## yacht422

cannot attach orig quote was $9400 + frt. to _manage_ the front of the room.

walt


----------



## yacht422




> Quote:
> Originally Posted by *yacht422* /forum/post/17884203
> 
> 
> cannot attach orig quote was $9400 + frt. to _manage_ the front of the room.
> 
> walt



to clarify: this $$ amount was for the front side walls of the room. i.e two front side walls, not the wall behind the screen.


----------



## yacht422




> Quote:
> Originally Posted by *kevinzoe* /forum/post/17883738
> 
> 
> Cold 'ya say . . .?! Why you southern types are a bunch of pansies - It's -20C with the windchill and -40C a couple of provences west of here, not that's cold!
> 
> 
> Walt -before you contact Denise Erskine (or anyone else) I'd highly recommend you read Dr Floyd Toole's book, which if nothing else will educate you enough to better communicate with and understand Denise's recommendations.
> 
> 
> I can't imagine that ASC's recommendation for just the front wall was going to cost US$10K - seems rather steep to me for a single wall. The front wall is the least important wall in my opinion and your Revel speakers are forward firing to boot so not sure what basis their reco's were based on.
> 
> 
> Cheers,
> 
> kevin



you do need to recognize that in fl we all walk naked!!









so - 20 deg f is extreme shrinkage weather.


----------



## nathan_h




> Quote:
> Originally Posted by *forestmoonstudio* /forum/post/17884015
> 
> 
> I am still wondering about framed movie posters on acoustic panels. Will the panels not work, because I would have a reflective surface on them?



The panels will not work as well, nor as they were designed.


----------



## kevinzoe




> Quote:
> Originally Posted by *forestmoonstudio* /forum/post/17884015
> 
> 
> I am still wondering about framed movie posters on acoustic panels. Will the panels not work, because I would have a reflective surface on them?



***************************

Forestmoonstudio:


If you bought the acoustic panels, then I'd suggest you call the manufacturer (if you haven't already done so) and ask them your question.


Otherwise, if the posters are made from paper then it'll be too thin to adversely affect the panel's performance except for the very highest frequencies; most frequencies will not even 'see' the paper. If it's glass over paper then I'd expect that it'll extend its reflective nature to lower frequencies which may or may not be a good thing. So, will you be able to hear the difference with and without the paper posters over the panels, likely not. As always try both ways and trust your ears.


If it's a bass trap you're using and you want just the low frequencies to be absorbed then by all means put a glass poster in front of it to help reduce the mid/upper frequency abosorption, but if it's mid/upper frequency absorption you seek, then it likely makes sense not to put a glass covered poster in front of the panel.


----------



## forestmoonstudio

Thank you for the advice guys. My room is only 16'x14' I will have columns on the walls and with that it will not leave alot of room. I know I will need the panels but I will try and put the framed posters on the panels and see how it sounds.


----------



## Weasel9992




> Quote:
> Originally Posted by *forestmoonstudio* /forum/post/17884015
> 
> 
> I am still wondering about framed movie posters on acoustic panels. Will the panels not work, because I would have a reflective surface on them?



They'll work, but they'll be much more reflective from the high mid range on up. Won't affect the low end qualities at all. The problem is, in HT set ups the person usually wants to put these kind of panels at the first reflection points, and that won't work. You'd want a more reflective panel away from reflection points...the corners or back wall would be fine.


Frank


----------



## captainkidd

I have recently built a home theater consisting of a 125" projector screen, Epson 1080P projector, Denon AVR 590 receiver and Klipsch Icon W series 5.1 speaker set up all connected through HDMI.

I am wondering if it will be possible for me to get good surround sound considering my rooms limitations.

The room is actually a converted RV garage. The entire garage WAS 70' deep by 20' wide by 16' high. It is built entirely out of concrete block with a VCT tile floor and sheetrock ceiling. The two end walls are huge roll up garage doors.

I walled off the last 30' of it by building a sheetrock wall with a set of double doors going into the 'new' garage. This 30' X 20' x 16' H rectangular room is the new man cave. It has a pool table, dart board, vending machine and now theater in it.


I will try to describe the room as best I can. The theater uses up about 12' of the rectangle starting along the new sheetrock wall. The screen is mounted on one concrete wall and the seating area is backed up near the opposite wall about 16'-18' away. So, the right hand speakers are in corners while the left hand speakers are near the front and rear walls but there is no left hand wall, just open space going over to the pool table ect.


When we attempted to watch our first movie the dialogue was very difficult to understand due to the poor room acoustics. I added a medium sized throw rug over the tile in front of the screen and built (6) 2' X 4' acoustic panels out of 2" thick owens corning 703, framed in pine, covered with a light cloth and stood off the walls about 2". I hung these starting at the first reflection point on the right hand wall and centered at ear height and basically continued them, evenly spaced every 10" along the side wall and along the rear wall, ending just past the seating are.

These changes helped quite a bit but certain parts of movie dialog still seem to disappear. I get the feeling that there is just too much reverb at certain tones and sometimes the bass seems to drown out everything.


So I am wondering if it is even possible to get good sound in a room like this or if I am just going to be stuck with mediocre sound due to the off balance design of the room? Any advice would be greatly appreciated.


----------



## zmisst




> Quote:
> Originally Posted by *pepar* /forum/post/17880027
> 
> 
> Walt, there are those that are saying early _lateral_ reflections are good. Ceiling, floor and rear wall are still treated. You're right about conventional wisdom, and I really have a hard time abandoning my thinking that the room should be neutralized as much as possible and the speakers should re-create the environment the artist created. New tech from companies like Audyssey and Dolby are aimed at expanding the front soundstage.
> 
> 
> Jeff



After taking a sabatical for a while glad to see that the "absorb-all-first-reflection" dogma continues to be under assault. Probably as a result of people reading Toole's book; and finding the occasional nugget of heresy from Dennis and even Terry now I see.


I looked into this issue quite a bit and concluded the following, based on primarily on Toole's book and evidence cited therein, and considering and contrasting all the conflicting advice given on this thread and in this forum:


In order of priority:

* add sound absorbing material (at least 3-4" thick) to front wall.

* add sound absorbing material or diffusers to center portion of rear wall

* consider diffusing/scattering surfaces on walls opposite surround speakers to enhance envelopment and help avoid flutter echoes.


If you think your side wall absorption makes the room sound better, try moving the side absorbers to the front or rear walls instead. (Don't just take them out of the room completely). By testing the absorbers in different locations in the room you will get the same effect on total room reverb, but will not interfere with the lateral reflections and will stead absorb more of the front and rear reflections which are of much more benefit (especially front).


While I was also drawn to the idea (and the cool applet that plotted the reflection points) I have seen nothing to show that there is a benefit to absorbing side wall first reflection points and there is persuasive evidence that absorption on the side walls is harmful since in blind tests people actually prefer side wall reflections: especially for speech intelligibility. 90% of most movie audio is dialogue, the dialogue is what we most concentrate on and lower speech intelligibility is very annoying.


Put your absorption on the front and rear and don't worry about the sides. If you still doubt, read Toole's book.


----------



## yacht422




> Quote:
> Originally Posted by *zmisst* /forum/post/17886639
> 
> 
> After taking a sabatical for a while glad to see that the "absorb-all-first-reflection" dogma continues to be under assault. Probably as a result of people reading Toole's book; and finding the occasional nugget of heresy from Dennis and even Terry now I see.
> 
> 
> I looked into this issue quite a bit and concluded the following, based on primarily on Toole's book and evidence cited therein, and considering and contrasting all the conflicting advice given on this thread and in this forum:
> 
> 
> In order of priority:
> 
> * add sound absorbing material (at least 3-4" thick) to front wall.
> 
> * add sound absorbing material or diffusers to center portion of rear wall
> 
> * consider diffusing/scattering surfaces on walls opposite surround speakers to enhance envelopment and help avoid flutter echoes.
> 
> 
> If you think your side wall absorption makes the room sound better, try moving the side absorbers to the front or rear walls instead. (Don't just take them out of the room completely). By testing the absorbers in different locations in the room you will get the same effect on total room reverb, but will not interfere with the lateral reflections and will stead absorb more of the front and rear reflections which are of much more benefit (especially front).
> 
> 
> While I was also drawn to the idea (and the cool applet that plotted the reflection points) I have seen nothing to show that there is a benefit to absorbing side wall first reflection points and there is persuasive evidence that absorption on the side walls is harmful since in blind tests people actually prefer side wall reflections: especially for speech intelligibility. 90% of most movie audio is dialogue, the dialogue is what we most concentrate on and lower speech intelligibility is very annoying.
> 
> 
> Put your absorption on the front and rear and don't worry about the sides. If you still doubt, read Toole's book.



i just ordered it. Amazon promises Toole's book next tues.









That said, what about the ceiling? I can move the side absorbers to the ceiling, which, again, _most_ posters seem to recommend.









I REALLY hate the thought that all the 2008 advice i've read/received was in error, and most of my room treatments are,basically,incorrect.









walt

but, again, my appreciation for the insights gained here!

(for the benefit on our Canadian friends out on the tundra in snuggies and mukluks, we in florida, the land of orange juice and bikini's, had snow this am.)


----------



## whumpf




> Quote:
> Originally Posted by *yacht422* /forum/post/17887568
> 
> 
> (for the benefit on our Canadian friends out on the tundra in snuggies and mukluks, we in florida, the land of orange juice and bikini's, had snow this am.)



What part of Florida? We have cold here, but not cold enough to snow (supposed to be 34 tonight).


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/17887568
> 
> 
> i just ordered it. Amazon promises Toole's book next tues.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> That said, what about the ceiling? I can move the side absorbers to the ceiling, which, again, _most_ posters seem to recommend.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I REALLY hate the thought that all the 2008 advice i've read/received was in error, and most of my room treatments are,basically,incorrect.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> walt
> 
> but, again, my appreciation for the insights gained here!
> 
> (for the benefit on our Canadian friends out on the tundra in snuggies and mukluks, we in florida, the land of orange juice and bikini's, had snow this am.)



*********************

Yikes, snow in the oranges and bikini belt?! So much for global 'warming.'


Walt, glad to hear that you've order THE book. I'll be sending you a PM regarding Chapter 22 that you'll find of interest.


I was thinking about your bass traps and lack of space and having to swap out SVS box subs for their cylinder cousins to safe floor space . . . Are you familiar with membrane/diaphragmatic bass traps that work differently than fibreglass-filled traps? The former work where the air PRESSURE is maximized (which is at the impact of the wall) and the latter work where the air particle MOTION is maximized which is one-quarter of the wavelength out from the wall. So, I would suggest you look at RPG's website, for example, for the diaphragmatic bass traps that hang on the wall and take up maybe 4"-6" vs the much thicker fibreglass filled resistive-type traps when floor space is scarce.


By the way, mukluks are back in style don't you know!


----------



## Bass Slut

captainkidd

i'm @ 4 post so y not

run you exact room dimensions through a room mode calculator

there are many, but you need to understand what freqs are overlapping

1130 ft per sec speed of sound /20' wide room / two trips = 28.25hz



30' long may not need treatment = 18.83hz & 37.6hz problems

20' = definate problems @ 28.25, but especially @ 56.5hz

16' will ring @ 35.3hz & 70.6hz bad

without running it through a mode overlap calculator, cause you didn't input inches, it looks like 3 homemade helmholtz resonantors place near the listening position would fix it all


i'd just make them 2.0cubic feet each, like a cheap speaker box, & tune each one to 56.5hz, 35.3hz & 70.6hz

i'd use 2.7" hole, no port on the 70hz, a 4" dia port on the 56hz & 3" id port on the 35hz

if your math is all right, you can tune the ports to the mm by ear yourself

i padded each helmholtz eff/ring time/bandwith by throwing in small rags, into the resonator 1 @ a time


the freqs octave up into the voice range & overlap...ooh


nothing else will work


----------



## yacht422

kevin: your pm was blocked - did not receive it - (i am a mac guy -that may be the reason.)

In advance, however, I thank you and will pay particular attention to #22.

Regarding the sub comments: Not me! I am not certain who you wanted to post your recommendation to, but, I do not have a space limitation.(16 X 23 X 10)

walt


----------



## yacht422

Kevin: I have the pm. Thanks mucho!!

Walt


----------



## Bass Slut

well i assume somebody has read all 190 pgs here & more


so my question is, is there a DIY thread on making helmholtz boxes to cancel root freq modes somewhere b4 i attempt to help people by making one w pics ??


i have searched

just trying to help


thx


Joe


----------



## glaufman




> Quote:
> Originally Posted by *Bass Slut* /forum/post/17898633
> 
> 
> well i assume somebody has read all 190 pgs here & more
> 
> 
> so my question is, is there a DIY thread on making helmholtz boxes to cancel root freq modes somewhere b4 i attempt to help people by making one w pics ??
> 
> 
> i have searched
> 
> just trying to help
> 
> 
> thx
> 
> 
> Joe



I'll admit I haven't searched, but I also haven't seen one, and I would love ot see one. Especially is it goes into designing one for certain freqs, BW, etc...


----------



## pepar




> Quote:
> Originally Posted by *whumpf* /forum/post/17887805
> 
> 
> What part of Florida? We have cold here, but not cold enough to snow (supposed to be 34 tonight).



It was 65 and raining in Cancun two nights ago. Had to wear a long sleeve shirt. Brrr.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *glaufman* /forum/post/17899058
> 
> 
> I'll admit I haven't searched, but I also haven't seen one, and I would love ot see one. Especially is it goes into designing one for certain freqs, BW, etc...



Links here:
http://www.mhsoft.nl/Helmholtzabsorb...zPanelAbsorber 
http://forum.studiotips.com/index.ph...4d625053ee43f6


----------



## johnbomb

Thanks, Kal, but the first link doesn't work.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *johnbomb* /forum/post/17907576
> 
> 
> Thanks, Kal, but the first link doesn't work.



I know but I was hoping it was just my computer that was at fault.


----------



## CruelInventions

Quotes edited and bolded for clarity:




> Quote:
> Originally Posted by *zmisst* /forum/post/17886639
> 
> 
> ......
> 
> I looked into this issue quite a bit and concluded the following, based on primarily on Toole's book and evidence cited therein, and considering and contrasting all the conflicting advice given on this thread and in this forum:
> 
> *In order of priority:
> 
> * add sound absorbing material (at least 3-4" thick) to front wall.*
> 
> * add sound absorbing material or diffusers to center portion of rear wall
> 
> * consider diffusing/scattering surfaces on walls opposite surround speakers to enhance envelopment and help avoid flutter echoes.
> 
> 
> If you think your side wall absorption makes the room sound better, try moving the side absorbers to the front or rear walls instead. (Don't just take them out of the room completely). By testing the absorbers in different locations in the room you will get the same effect on total room reverb, but will not interfere with the lateral reflections and will stead absorb more of the front and rear reflections which are of much more benefit (especially front).
> 
> 
> ..........
> 
> 
> Put your absorption on the front and rear and don't worry about the sides. If you still doubt, read Toole's book.





> Quote:
> Originally Posted by *kevinzoe* /forum/post/17883738
> 
> 
> .........
> 
> 
> Walt -before you contact Denise Erskine (or anyone else) I'd highly recommend you read Dr Floyd Toole's book, which if nothing else will educate you enough to better communicate with and understand Denise's recommendations.
> 
> 
> I can't imagine that ASC's recommendation for just the front wall was going to cost US$10K - seems rather steep to me for a single wall. *The front wall is the least important wall* in my opinion and your Revel speakers are forward firing to boot so not sure what basis their reco's were based on.
> 
> 
> Cheers,
> 
> kevin



Seeming descrepancy here regarding the front wall treatment recommendation; one person says it's important, the other, not so much. Both naming Toole's work/advice as a primary source of expertise.


Have one of you misinterpreted Toole's work? Or is there some subtle nuance I am missing in which both of you may be correct?


My previous but somewhat vague impression has been that front wall treatment is recommended for 5.1 or more multi-channel rooms, but not so important for a strictly 2 channel type music room. Of course, corner-type bass treatments being a different discussion.


Thanks in advance.


----------



## mike2060

Covering the whole front wall is good for HT because the surrounds don't get reflected and for SBIR.


For 2 channel as long as your speakers are far enough from the walls usually diffusion is used I believe. If you speakers are close to the walls you need some absorption behind them for SBIR.


----------



## Weasel9992




> Quote:
> Originally Posted by *mike2060* /forum/post/17909066
> 
> 
> Covering the whole front wall is good for HT because the surrounds don't get reflected and for SBIR.



There's some debate on this point, but I would agree.



> Quote:
> Originally Posted by *mike2060* /forum/post/17909066
> 
> 
> For 2 channel as long as your speakers are far enough from the walls usually diffusion is used I believe. If you speakers are close to the walls you need some absorption behind them for SBIR.



This is really room and speaker-dependent. Sometimes diffusion on the front wall is appropriate, but lots of times it's not.


Frank


----------



## Ethan Winer




> Quote:
> Originally Posted by *johnbomb* /forum/post/17907576
> 
> 
> Thanks, Kal, but the first link doesn't work.



That site seems to be gone, for now anyway. I have the calculator (Windows only), and I'm glad to email it to anyone who wants it. Reach me through my home page:

www.ethanwiner.com 


--Ethan


----------



## yacht422




> Quote:
> Originally Posted by *Weasel9992* /forum/post/17909415
> 
> 
> There's some debate on this point, but I would agree.
> 
> 
> 
> 
> This is really room and speaker-dependent. Sometimes diffusion on the front wall is appropriate, but lots of times it's not.
> 
> 
> Frank



what/how does one treat the front wall when it is mostly screen?

although my room is 16+' wide, there are no front corners, as such.

the front of the room has a four foot mini wall at 45deg from the flat walls.

(ref pic : easier than explaining)

walt


----------



## Ethan Winer




> Quote:
> Originally Posted by *yacht422* /forum/post/17911234
> 
> 
> what/how does one treat the front wall when it is mostly screen?



Wall-floor and wall-ceiling corners are good, and flat on the wall behind the screen can help too if you have at least 3 or 4 inches or more space.



> Quote:
> the front of the room has a four foot mini wall at 45deg from the flat walls.



Why are those corners walled off? Can you remove that?


--Ethan


----------



## kevinzoe




> Quote:
> Originally Posted by *CruelInventions* /forum/post/17908081
> 
> 
> Quotes edited and bolded for clarity:
> 
> 
> 
> 
> 
> 
> 
> Seeming descrepancy here regarding the front wall treatment recommendation; one person says it's important, the other, not so much. Both naming Toole's work/advice as a primary source of expertise.
> 
> 
> Have one of you misinterpreted Toole's work? Or is there some subtle nuance I am missing in which both of you may be correct?
> 
> 
> My previous but somewhat vague impression has been that front wall treatment is recommended for 5.1 or more multi-channel rooms, but not so important for a strictly 2 channel type music room. Of course, corner-type bass treatments being a different discussion.
> 
> 
> Thanks in advance.



*******************************

CruelInventions - sorry for the confusion. I expect it's my fault. My statement that the front wall is likely the least important wall to treat was in the context of 2-ch stereo not HT and that the 2-Ch stereo speakers are forward firing. Reason being is that a number of factors combine to make the sound from the front wall much less audible than say 1st reflection points off side walls, ceiling, and floor. From Toole's book, these factors include:

* sound energy propogation loss or decline in steady-state sound level as a function of distance through air at about -3dB per double distance

* reduced sound energy upon impact with surfaces that are absorbing or diffusing before traveling to the front wall

* precedence effect caused our attention to focus on the first arrival/direct sound and we simply are not aware of the reflections as spatially seperate events, or much less so.


For HT, Toole recommends 3-4" minimum thickness of absorption in the centre portions of the front and back walls.


Hope this helps . . .


----------



## Electric_Haggis




> Quote:
> Originally Posted by *yacht422* /forum/post/17911234
> 
> 
> what/how does one treat the front wall when it is mostly screen?
> 
> although my room is 16+' wide, there are no front corners, as such.
> 
> the front of the room has a four foot mini wall at 45deg from the flat walls.
> 
> (ref pic : easier than explaining)
> 
> walt



For what it's worth, I use the inch or so behind my screen & curtains to store the packing foam & cardboard for my speakers. There's also a thin layer of acoustic polyroll material.


Apart from helping to reduce a little transmission to the next apartment, it makes a noticeable difference to the liveness and bass boom of the room.


You can see this below...


----------



## erkq




> Quote:
> Originally Posted by *yacht422* /forum/post/17911234
> 
> 
> what/how does one treat the front wall when it is mostly screen?



I know. That big flat reflective surface can be a problem. This is one of the overlooked advantage of an AT screen.


----------



## yacht422




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17914673
> 
> 
> Wall-floor and wall-ceiling corners are good, and flat on the wall behind the screen can help too if you have at least 3 or 4 inches or more space.
> 
> 
> 
> 
> Why are those corners walled off? Can you remove that?
> 
> 
> --Ethan



no- it has to do with the overall design of the space - there is a full bathroom to the right of the h/t, and we needed space to enter the shower:ergo. angled wall.

the opposite wall holds a small closet, and was built as an "aesthetic".(balanced the room visually.)


----------



## yacht422

ethan, the screen is mounted directly on the wall. i'd need to make standoffs to move it out. are there _sound_ reasons to do so?

then the next question is 4" of what, and wall to wall, i presume.

walt


----------



## LotToLearn

I searched everywhere but can find the answer - is Owens Corning 703 a fire retardant material? I am planning to build panels for my room using these panels covered with GOM FR701 but want to make sure the panels themselves will not be a fire hazard.


----------



## Weasel9992




> Quote:
> Originally Posted by *LotToLearn* /forum/post/17923276
> 
> 
> I searched everywhere but can find the answer - is Owens Corning 703 a fire retardant material? I am planning to build panels for my room using these panels covered with GOM FR701 but want to make sure the panels themselves will not be a fire hazard.



No, it is not. Panels are made with 703, flame tested and certified all the time.


Frank


----------



## Ethan Winer




> Quote:
> Originally Posted by *yacht422* /forum/post/17917899
> 
> 
> are there _sound_ reasons to do so?



Yes, all rooms need plenty of bass trapping.



> Quote:
> then the next question is 4" of what, and wall to wall, i presume.



4 inches of rigid fiberglass. Even more at the bottom if possible, straddling the wall-floor corner fully from left to right.


--Ethan


----------



## yacht422

ethan: many thanks!

walt


----------



## pocoloco

Some food for thought....


I've been reading Sound Reproduction by Floyd Toole and it says that bass traps using resistive absorption (ie: rigid fiberglass) placed at wall boundaries/corners are ineffective because those are high pressure regions. For fiberglass to be effective, it needs to be placed in high VELOCITY regions which work out to be away from wall boundaries. And placing fiberglass away from wall boundaries is not very practical.


So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window. He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.


----------



## pepar




> Quote:
> Originally Posted by *pocoloco* /forum/post/17932316
> 
> 
> Some food for thought....
> 
> 
> I've been reading Sound Reproduction by Floyd Toole and it says that bass traps using resistive absorption (ie: rigid fiberglass) placed at wall boundaries/corners are ineffective because those are high pressure regions. For fiberglass to be effective, it needs to be placed in high VELOCITY regions which work out to be away from wall boundaries. And placing fiberglass away from wall boundaries is not very practical.
> 
> 
> So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window. He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.



well, those who are packing their corners are not just sticking a little there. many use the 17" face chunk design, and some have the luxury (of space) to use the 24" face. my understanding of why to trap the corner is that ALL modes are present there.


wishful thinking?







yeah, maybe that's what cleaned up the overhang in my room that used to be present in the waterfalls.


----------



## mike2060




> Quote:
> Originally Posted by *pocoloco* /forum/post/17932316
> 
> 
> Some food for thought....
> 
> 
> I've been reading Sound Reproduction by Floyd Toole and it says that bass traps using resistive absorption (ie: rigid fiberglass) placed at wall boundaries/corners are ineffective because those are high pressure regions. For fiberglass to be effective, it needs to be placed in high VELOCITY regions which work out to be away from wall boundaries. And placing fiberglass away from wall boundaries is not very practical.
> 
> 
> So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window. He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.



He may be talking about removing the room modes rather than just decreasing decay time.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pocoloco* /forum/post/17932316
> 
> 
> So basically the common rule here to pack corners full of fiberglass to work as bass traps goes out the window.



Not in this universe. My company's video Hearing is Believing shows a huge before/after change with a lot of bass traps, and in this case the traps aren't even straddling corners. Floyd is correct in theory, but in practice you don't have to put panels several feet out from the wall to make a huge improvement. The video above shows a very large improvement in the response and ringing to 40 Hz and below.



> Quote:
> He actually goes as far to say that acoustic companies that produce fiberglass products that fit into corners and marketed as "bass traps" is ineffective and is more "wishful thinking". If you want bass traps at the corners, membrane absorbers or resonators are the way to go.



Again, he is wrong - and easily _proven_ wrong - in the above video as well as in many other articles, videos, and graphs all over my company's web site.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/17937035
> 
> 
> many use the 17" face chunk design, and some have the luxury (of space) to use the 24' face.



34 inches rules!


----------



## yacht422




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17938010
> 
> 
> 34 inches rules!



is this 34" deep, or, 34" across the front of the corner(i.e. the hypotenuse)

i currently am 17" deep X 34" front X eight feet, floot to ceiling, GOM faced.

walt


----------



## yacht422




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17924934
> 
> 
> Yes, all rooms need plenty of bass trapping.
> 
> 
> 
> 
> 4 inches of rigid fiberglass. Even more at the bottom if possible, straddling the wall-floor corner fully from left to right.
> 
> 
> --Ethan



when you say 'more', how much? and, related, is this a product your company mfgs?

you may pm me if you choose not to respond in this thread.

thx

walt


----------



## yacht422

new question.

we _all_ cover the f/g with GOM. is there any knowledge/statistics about covering the rigid f/g with plastic screening? (as in 'screen door' screening.)

walt


----------



## gremmy




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17937997
> 
> 
> Not in this universe. My company's video Hearing is Believing shows a huge before/after change with a lot of bass traps, and in this case the traps aren't even straddling corners. Floyd is correct in theory, but in practice you don't have to put panels several feet out from the wall to make a huge improvement. The video above shows a very large improvement in the response and ringing to 40 Hz and below.
> 
> 
> 
> 
> Again, he is wrong - and easily _proven_ wrong - in the above video as well as in many other articles, videos, and graphs all over my company's web site.
> 
> 
> --Ethan




And to second what you're saying, Ethan, all anyone has to do to actually "see" the difference that can be obtained with corner mounted bass traps is to download REW and measure the in-room response before and after. This is important for people to do anyway, since everyone's room is different and very few match the models exactly. If you put your absorption in the right place (and in the right amounts), the difference, both measured and audible, is *not* subtle.


----------



## Spaceman












In this scenario, do I need corner bass traps beside the screen wall in the main room AND behind the screen, where I currently show the 2" of 703? The cross-hatched patterns indicate the bass traps and the 2" of 703 up against the wall.


I'm hoping to put the sub, mains and ctr behind an AT screen. One concern I have is with imaging. If the mains go behind the screen, they will only be 6' apart at the most. Front row viewing will be from 9 1/2'. Will the mains be too close together? Moving them to the sides gets problematic because they would need to sit in front of the duct, but I don't want to move the screen any further into the room. I'm hoping behind the screen is ok.


----------



## Ethan Winer




> Quote:
> Originally Posted by *yacht422* /forum/post/17938780
> 
> 
> is this 34" deep, or, 34" across the front of the corner(i.e. the hypotenuse)



That was half meant as a joke, because my company recently started offering a filled corner trap that's 34 inches wide across the front face.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *gremmy* /forum/post/17941788
> 
> 
> all anyone has to do to actually "see" the difference that can be obtained with corner mounted bass traps is to download REW and measure the in-room response before and after. This is important for people to do anyway



Yes and Yes.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Spaceman* /forum/post/17943681
> 
> 
> In this scenario, do I need corner bass traps beside the screen wall in the main room AND behind the screen wall in the recessed cavity?



IMO, in _every_ scenario you want as much bass trapping as possible.


--Ethan


----------



## yacht422

so, my present arrangement is ok, i presume.

( i also have two 2'X4'X4" 701 panels on the rear wall, each on either side of a double wide window that i have "faced" with a 4" X 4' X 6' panel.)

you had mentioned bass trapping at the front wall, floor to wall, 4" min. thick.

Do you offer this , and is 6" better than 4"?(or, is this another diy project that will yield acceptable results)

(i am running two subs, and a pair of full range spkrs, front firing, ported 360 deg. at the bottom. (REVEL Ultima Salons)

walt


----------



## yacht422




> Quote:
> Originally Posted by *Spaceman* /forum/post/17943681
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> In this scenario, do I need corner bass traps beside the screen wall in the main room AND behind the screen, where I currently show the 2" of 703? The cross-hatched patterns indicate the bass traps and the 2" of 703 up against the wall.
> 
> 
> 
> 
> Quote:
> I'm hoping to put the sub, mains and ctr behind an AT screen. One concern I have is with imaging. If the mains go behind the screen, they will only be 6' apart at the most. Front row viewing will be from 9 1/2'. Will the mains be too close together? Moving them to the sides gets problematic because they would need to sit in front of the duct, but I don't want to move the screen any further into the room. I'm hoping behind the screen is ok
> 
> 
> 
> 
> .
Click to expand...


toole et al. recommend mains be as far apart as is the distance to the listener.(8 feet apart =8 feet to the listener.) a narrower mains measurement will reduce the sound stage, but, then, speakers behind the screen will cost sonic value as well. your choice.

walt


----------



## tccolv

My head is spinning and my theater is a-waiting....
http://www.avsforum.com/avs-vb/images/smilies/eek.gif 

I was all set to completely cover my front wall (18' x 9') with 2" DIY Rockwool panels. I changed course based on some threads saying that 2" was too much absorption, so instead, in each corner, I hung 2' x 8' 4" thick panels and bought enough 1" 703 to do the center 14'. The 703 will be framed on 1/4" 4x8 luan sheets.


Now I read (at about post 175) that 3"-4" is the cats meow for the front wall. Too late! Panels built. So I'm wondering if my luan backed 1" panels were hung on furring strips giving me 2" gap from the wall, would the 703 faced luan act as a diaphamic basstrap, if so, how much, or would it even be worth bothering with?


Any feedback?


----------



## Weasel9992




> Quote:
> Originally Posted by *tccolv* /forum/post/17949756
> 
> 
> Now I read (at about post 175) that 3"-4" is the cats meow for the front wall. Too late! Panels built. So I'm wondering if my luan backed 1" panels were hung on furring strips giving me 2" gap from the wall, would the 703 faced luan act as a diaphamic basstrap, if so, how much, or would it even be worth bothering with?
> 
> 
> Any feedback?



Well...at some frequency it probably does. There's no way to know unless you test it. 1" 703 is fine for the front wall though...3"-4" is great if the room is small and you need more low frequency absorption, but I think you'll be alright the way you are. How does it sound? Have you had a chance to give the room a test run?


Frank


----------



## jlupo

the equal lateral triangle is always best for stereo imaging. Optimum timbre and imaging is obtained when you point (toe-in) the speakers towards the listening position. Also pulling them away from the wall will open up the sound, increase spaciousness and improve imaging. I have mine 4' off the screen wall with a 15 degree toe-in angle. Just open them up the best you can.


----------



## dweltman

I am thinking about putting some of the panels with art prints in my room. They would go behind my listening position. The listening seats are pretty close to the rear wall, about 2-3 feet. The ASC panels claim to have diffusion strips, which they say are ideal for this sort of location. Something about the sound being too "dead" if you are too close to a panel that is straight absorbing. Would this really be advantageous as compared to other panels?


----------



## Weasel9992




> Quote:
> Originally Posted by *dweltman* /forum/post/17960267
> 
> 
> I am thinking about putting some of the panels with art prints in my room. They would go behind my listening position. The listening seats are pretty close to the rear wall, about 2-3 feet. The ASC panels claim to have diffusion strips, which they say are ideal for this sort of location. Something about the sound being too "dead" if you are too close to a panel that is straight absorbing. Would this really be advantageous as compared to other panels?



No, it's not. The closer you are to the back wall, the more absorption becomes necessary to deal with the strong reflections.


Frank


----------



## jcieutat

OK, since good advice is being dished out here I thought I would jump in. I am new to the home theater world. We are in the construction phase of our addition that will be a home theater. The room is basically 18' x 14' with a 9' ceiling. In the room there is also a 2' x 6' insert for the computer area. So the room is not perfectly rectangular. It would have been 18' x 16' but it is behind our living room fireplace so it goes into this room which is an addition. We are going with spray foam insulation for energy efficiency. The walls and ceiling will be sheetrock and the flooring will be engineered hardwood. My audio will be KEF HTS5005.2 with a set of Proficeint Audio in ceiling speakers for the rear channels. I am told I need to add some acoustical panels into the room. I am kind of confused about the placement. I was going to build columns to house them because I want the room to have a clean look and not have panels hanging on the walls everywhere. Do these things need to be directly across from the speakers? Any advise would be greatly appreciated. Tomorrow I will scan in the floor plan and post it here.


----------



## humyt

I'm planning to install some diffusors on the rear side walls of the room, just wondering if the layout of the diffusors needs to be symmetrical on both side walls?


Can I install say 3 pieces of 2' x 2' diffusors on the left side wall and 1 piece on the right side wall? This is due to an existing cabinet obstructing some parts of the rear right side wall.


----------



## Ethan Winer

^^^ Yes, symmetry is important. But the side walls toward the back of the room are not the first place I'd put diffusors. The rear wall makes more sense.


--Ethan


----------



## dweltman

Ethan:

so then the conclusion is that the rear wall is a good place for diffusion, but diffusors lose efficacy if your listening position is too close to the rear wall?


----------



## kevinzoe




> Quote:
> Originally Posted by *humyt* /forum/post/17970256
> 
> 
> I'm planning to install some diffusors on the rear side walls of the room, just wondering if the layout of the diffusors needs to be symmetrical on both side walls?
> 
> 
> Can I install say 3 pieces of 2' x 2' diffusors on the left side wall and 1 piece on the right side wall? This is due to an existing cabinet obstructing some parts of the rear right side wall.



*****************

Humyt - diffusion on the rear side walls does not need to be symetrical. I have a GIK D1 diffusor on the rear left side wall and a Skyline diffuser across from it on the right side wall and when one is removed there is very little sonic affect because just one is sufficient to attenuate flutter echo between the rear side walls. So, of course you should experiment but I would predict that having 2-3 on one rear side wall and only 1 on the opposite won't hurt things at all. Dr. Floyd Toole in his latest book shows various HT acoustical setups and there are examples of differing diffusion treatments across from each other (e.g. hemicylindrical, QRD diffusers.)


I agree with Ethan that diffusion on the back wall is where I put my first diffusers before the rear side walls. What kind of diffuser are you thinking of using because it's thickness (aka deepest well or cell depth) should be a minimum of 8" and work down to 300Hz and then use bass traps for


----------



## humyt

Thanks for the advice Ethan and Kevinzoe. I am thinking of trying out the Aurelex T-Fusor which is also 6" thick as the GIK D1 diffusor. The planned locations for them are:


a) 1 panel at each corner of the rear wall at ear height


b) 4 panels at first reflection point on the ceiling


c) 1 panel to each side wall of the main listening position at ear height


Front and rear walls (middle part) will use absorption as per Dr.Toole's book Chp. 22.


1 bass trap at each wall/ceiling corners (Auralex LENRD).


Does this sound right? My usage will be mainly for movies (7.2 channels + DSX wides setup). Room size is 4.3m(W) x 6.5m (L) x 2.5m (H).


----------



## kevinzoe

Humyt - If you're buying Auralex then don't expect Ethan to respond as he reqpresents a 'competitor' to Auralex.


6" deep diffusers - GIK D1 or Auralex T-Fusor - aren't really deep enough to diffuse really effectively down to +-300Hz which represents your estimated room's Schroeder frequency or transition frequency. Have you considered building a Skyline or hemicyclindrical diffuser which can be customized to your needs and offers greater depth flexibility? Just a thought . . .


Regarding your point "a) 1 panel at each corner of the rear wall at ear height" I think bass traps should go there not diffusion.


Regarding your point "c) 1 panel to each side wall of the main listening position at ear height" I don't think you need anything on the side walls directly beside the listening chair as reflections hitting this spot will bounce ahead or behind you so aren't an issue. Instead try experimenting with the diffusers on the side wall's 1st reflection points which is slightly ahead of the listening position but not quite to the speakers.


Have you read Toole's book as you mentioned chapter 22 . . .? If so, lots of 'sound' advice in it for you.




> Quote:
> Originally Posted by *humyt* /forum/post/17977132
> 
> 
> Thanks for the advice Ethan and Kevinzoe. I am thinking of trying out the Aurelex T-Fusor which is also 6" thick as the GIK D1 diffusor. The planned locations for them are:
> 
> 
> a) 1 panel at each corner of the rear wall at ear height
> 
> 
> b) 4 panels at first reflection point on the ceiling
> 
> 
> c) 1 panel to each side wall of the main listening position at ear height
> 
> 
> Front and rear walls (middle part) will use absorption as per Dr.Toole's book Chp. 22.
> 
> 
> 1 bass trap at each wall/ceiling corners (Auralex LENRD).
> 
> 
> Does this sound right? My usage will be mainly for movies (7.2 channels + DSX wides setup). Room size is 4.3m(W) x 6.5m (L) x 2.5m (H).


----------



## Lightspeed66

Room treatment is one area I hadn't even considered, and don't know if I would have even missed it if it wasn't there. That said, I'm picky about the sound and have $$ invested.


If I had $100 and DIY, where would be the first place to put something to have the biggest effect? i may add more later, but for now I've got to keep it small.

ATS has some Roxul Rockboard 60 I could use in 2x4 panels.


My room is 8 foot ceiling, maybe 18-20 deep and 12 wide? Curtains along one side wall, back of room has desk and computer setup in one corner and stairs in the other. Viewing/seating is about midway into the room, center.


I could fit:


-1 to 3 panels along side wall on right.

-several panels on the wall behind the mains and tv (50").

-MAYBE something on back wall center, although WAF would crumble.

-corners behind mains and tv, maybe.


$$ wise $100 would get me about 4 panels of that size with cloth and hardware. Where should I focus energy? Will it even do anything?


----------



## Ethan Winer




> Quote:
> Originally Posted by *dweltman* /forum/post/17974103
> 
> 
> So then the conclusion is that the rear wall is a good place for diffusion, but diffusors lose efficacy if your listening position is too close to the rear wall?



Not exactly. In fact, diffusion probably is less necessary if you're very far from the rear wall because the distance alone will spread the sound. Plus, reflections from a distant surface are weaker and so less damaging. My main point is that the side walls are out of the way of the "line of fire" so to speak, so that's a less important location.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *humyt* /forum/post/17977132
> 
> 
> I am thinking of trying out the Aurelex T-Fusor which is also 6" thick as the GIK D1 diffusor.



GIK's diffusor is a genuine QRD type. The T-Fusor is not nearly as good IMO.


--Ethan


----------



## bpape

Just as a follow-up, the D1 has a higher cutoff on the top end as some of the well faces are polys to extend it to over double what a standard well face would do.


I would also agree with Ethan with regard to the side wall placement vs behind the seating. Another location that's 'out of the line of fire' is up high on the walls where you're primarily looking to minimize slap echo.


Bryan


----------



## Lightspeed66

OK read much more. Thanks for the articles Ethan.


I'm going to try one panel on the right wall at a reflection point, and bass traps in the corners behind the mains and tv. Would additional panels behind each main speaker be useful?


Not sure on materials and design of the bass traps themselves, but it will be all DIY. Also, not sure if upper and lower corners or floor to ceiling? Would just one 2x4 panel be effective? BTW, the sub is located in the corner to the left of the mains if that matters.


----------



## yacht422

does rockwool (slab form) offer _as good_ or _better_ performance than oc 703 for floor to wall trapping?

i am considering 6" wlde X 16" hi X 10 feet long.( front wall under screen.)

walt

(this is in response to an earlier comment by ethan - bass trap the front under the screen)


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/17982867
> 
> 
> does rockwool (slab form) offer _as good_ or _better_ performance than oc 703 for floor to wall trapping?
> 
> i am considering 6" wlde X 16" hi X 10 feet long.( front wall under screen.)
> 
> walt
> 
> (this is in response to an earlier comment by ethan - bass trap the front under the screen)



Walt - check out this link for absorption coefficients between various products, including OC and Rockwool and Roxl:
http://www.bobgolds.com/AbsorptionCoefficients.htm 


By the way, how goes the reading of 'the book?'







Your impressions?


If one is to build bass traps and have an air space behind the trap, then why are people using OC 703 when 701 has a higher 125Hz absorption coefficient??? I contrasted OC 701 3" thickness (using the 16" air space specs on the link above) with OC 703 3" and 4" thickness and in both cases the 701 less dense material had better low freq absorption. So why do people seem disposed to get 703 instead?


At 1KHz the trend is reversed with OC 703 being more absorbent than 701, but for bass traps I don't want 1KHz absorbed, I want it either reflected or diffused.


----------



## Elill

Anyone know what the minimum recommended seating distance is from a BAD panel?


Also if anyone can tell me the diameter of the holes that would be useful.


----------



## humyt




> Quote:
> Originally Posted by *kevinzoe* /forum/post/17979446
> 
> 
> Regarding your point "a) 1 panel at each corner of the rear wall at ear height" I think bass traps should go there not diffusion.
> 
> 
> Regarding your point "c) 1 panel to each side wall of the main listening position at ear height" I don't think you need anything on the side walls directly beside the listening chair as reflections hitting this spot will bounce ahead or behind you so aren't an issue. Instead try experimenting with the diffusers on the side wall's 1st reflection points which is slightly ahead of the listening position but not quite to the speakers.
> 
> 
> Have you read Toole's book as you mentioned chapter 22 . . .? If so, lots of 'sound' advice in it for you.



Really appreciate your advice kevinzoe. Perhaps I didn't phrase it correctly, what I meant to say was placing 1 panel each towards the side of the rear wall. I do intend to place bass traps at the corners.


As for the diffusors at the side walls, I was thinking of following what was suggested in Figure 22.3 (page 506) of Dr. Toole's book, specifically Wall B, where a long array of engineered diffusors lined quite a fair bit of the side wall. Is this a good practice for multi-channel setup?


----------



## humyt




> Quote:
> Originally Posted by *bpape* /forum/post/17981274
> 
> 
> Just as a follow-up, the D1 has a higher cutoff on the top end as some of the well faces are polys to extend it to over double what a standard well face would do.
> 
> 
> I would also agree with Ethan with regard to the side wall placement vs behind the seating. Another location that's 'out of the line of fire' is up high on the walls where you're primarily looking to minimize slap echo.
> 
> 
> Bryan



Thanks Bryan, the D1 looks better too! I will definitely look into it.


BTW what can be used to treat slap echo?


----------



## yacht422




> Quote:
> Originally Posted by *kevinzoe* /forum/post/17983024
> 
> 
> Walt - check out this link for absorption coefficients between various products, including OC and Rockwool and Roxl:
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> 
> By the way, how goes the reading of 'the book?'
> 
> 
> 
> 
> 
> 
> 
> Your impressions?
> 
> 
> If one is to build bass traps and have an air space behind the trap, then why are people using OC 703 when 701 has a higher 125Hz absorption coefficient??? I contrasted OC 701 3" thickness (using the 16" air space specs on the link above) with OC 703 3" and 4" thickness and in both cases the 701 less dense material had better low freq absorption. So why do people seem disposed to get 703 instead?
> 
> 
> At 1KHz the trend is reversed with OC 703 being more absorbent than 701, but for bass traps I don't want 1KHz absorbed, I want it either reflected or diffused.



kevin: re: book. pg 86; it's like the bible - cannot read it once and understand it all.


----------



## kamich70

soooo... after reading all of this... what would someone on here charge me to tell me what to put where if I can give room dimensions, etc??


----------



## nathan_h

It's likely, though you mention "soundproofing" whereas most of this discussion is not about keeping sound in the room (ie soundproofing), but, rather, about making the room itself better for the sound inside of it (ie acoustic treatment).


----------



## Weasel9992




> Quote:
> Originally Posted by *kamich70* /forum/post/17990336
> 
> 
> soooo... after reading all of this... what would someone on here charge me to tell me what to put where if I can give room dimensions, etc??



It depends on what you actually need. If it's simple acoustic treatment, then the vendors here won't charge you anything. If it's room design, then there are several highly qualified professionals who post here all the time. I'm not privvy to their rates, but you could simply PM them.


Frank


----------



## pepar




> Quote:
> Originally Posted by *kamich70* /forum/post/17990336
> 
> 
> soooo... after reading all of this... what would someone on here charge me to tell me what to put where if I can give room dimensions, etc??



As you probably "got" from Frank's post, there is more to it than "here are my dims, what do I put where?" It *might* be that simple, but then it might not and you do more harm than good.


If you are taking the DIY route to sound _treatments_, you will need a (free) app like Room EQ Wizard and a (not free) calibrated mic.


Jeff


----------



## jjmbxkb

Hi, in the process of treating my room, and got the following questions:


1. What is the performance difference between a foam corner bass trap and a 4" OC703 panel mounted at the corner?


2. Particularly, has anybody had any experience with this? http://www.prosoundfoam.com/12_in_Pr...p-details.aspx 


Thanks very much for any information.


----------



## Weasel9992




> Quote:
> Originally Posted by *jjmbxkb* /forum/post/18002199
> 
> 
> Hi, in the process of treating my room, and got the following questions:
> 
> 
> 1. What is the performance difference between a foam corner bass trap and a 4" OC703 panel mounted at the corner?
> 
> 
> 2. Particularly, has anybody had any experience with this? http://www.prosoundfoam.com/12_in_Pr...p-details.aspx
> 
> 
> Thanks very much for any information.



I'm really not being a bit flippant when I say the difference is, 4" of OC703 straddling a corner actually works and foam does not. It simply is not a good source for bass trapping. You really only have to view the lab test data to see the very clear distinction. Even if you were to use foam, by the time you'd used enough to equal the effectiveness of a panel trap you'd have spent much more than you would have on even a commercially purchased panel.


Frank


----------



## jjmbxkb




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18002234
> 
> 
> I'm really not being a bit flippant when I say the difference is, 4" of OC703 straddling a corner actually works and foam does not. It simply is not a good source for bass trapping. You really only have to view the lab test data to see the very clear distinction. Even if you were to use foam, by the time you'd used enough to equal the effectiveness of a panel trap you'd have spent much more than you would have on even a commercially purchased panel.
> 
> 
> Frank



Frank, thanks very much for the quick response. That makes it pretty simple, I will use panels then.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *jjmbxkb* /forum/post/18002199
> 
> 
> Hi, in the process of treating my room, and got the following questions:
> 
> 
> 1. What is the performance difference between a foam corner bass trap and a 4" OC703 panel mounted at the corner?



Try www.realtraps.com where there are measurements of similar devices.


----------



## maxfli

Someone had posted previously about placing a movie poster over a 2' x 4' acoustic panel and if I recall other than as a bass trap, this was Ok. How about something like this?

http://cgi.ebay.com/WISCONSIN-BADGER...item20af12e024 


I imagine it's about 1/16" or less think wool banner. Thanks in advance.


----------



## jjmbxkb




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18002675
> 
> 
> Try www.realtraps.com where there are measurements of similar devices.




Thanks for the link. It really helps me with the basics.


----------



## forestmoonstudio

How much would 1.1 life size standups absorb sound? I will have at least three on one side wall and one on the other smaller side wall. The back wall will have curtains covering a bay window. The front wall is the screen wall.


Would I really need acoustic panels if I have these guys blocking most of the wall space?


My Darth Vader:


----------



## pepar

You're kidding, right?


----------



## NJ Jackals

I *think* what he's asking is that he knows the popups are a reflective surface so would that largely defeat a treated wall behind it. Either way, the answer to "would I really need acoustic panels" is "yes".


----------



## forestmoonstudio

PEPAR, no I am not kidding.










NJ, these are not cardboard standups. These are costumes on manniquins. Sorry for the confusion. Do you think they will absorb or reflect sound? I would think that a body ( Human or mannequin ) would absorb sound. I would hate to buy acoustic panels only to be covered up by my mannequins.


----------



## Terry Montlick

Hard and curvy, so in general good diffusers. You could still benefit from acoustic panels, because indirect sound will still reach behind the mannequins and improve reverberation times and dialog intelligibility.


----------



## forestmoonstudio

Thank you Terry. That answers my question.


----------



## KERMIE

Anyone know at what Frequencies the average NON-AT screen reflects and lets pass through?


The thought was since my Screen will be about 2 Feet in front of the front wall to build a 4 inch deep SEALED frame filling with Rigid Fiberglass then set the screen (100" diag) on the frame. You would have a:


94" x 56" x 4" trap floating 2 feet off the front wall centered between the left/right, floor/ceiling.


Would this do any low/mid Bass Trapping even though it is not in a corner?


----------



## yacht422




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18010003
> 
> 
> Hard and curvy, so in general good diffusers. You could still benefit from acoustic panels, because indirect sound will still reach behind the mannequins and improve reverberation times and dialog intelligibility.



This begs the question: is it the _shape_ that matters, or the _construction_ material that matters(or a little of both)?

If one were planning on half round diffusers, floor to ceiling, would it matter if one were to use the _cardboard_ footing tubes(cut in half) or _plastic_ pipe(again, cut in half) etc.

Would they be placed empty against the wall, or filled with f/g or rock wool. - - - or, in the final analysis, are commercially manufactured tubes truely the best way to go?! (toole recommends a combo of tubes and shapes -i am looking at tubes, for now)

Walt


----------



## Terry Montlick




> Quote:
> Originally Posted by *yacht422* /forum/post/18013252
> 
> 
> This begs the question: is it the _shape_ that matters, or the _construction_ material that matters(or a little of both)?
> 
> If one were planning on half round diffusers, floor to ceiling, would it matter if one were to use the _cardboard_ footing tubes(cut in half) or _plastic_ pipe(again, cut in half) etc.
> 
> Would they be placed empty against the wall, or filled with f/g or rock wool. - - - or, in the final analysis, are commercially manufactured tubes truely the best way to go?! (toole recommends a combo of tubes and shapes -i am looking at tubes, for now)
> 
> Walt



I was only addressing the special case of manniquins space somewhat away from the wall. Hard convex rather than concave surfaces should always be used.


----------



## Weasel9992




> Quote:
> Originally Posted by *forestmoonstudio* /forum/post/18009313
> 
> 
> Would I really need acoustic panels if I have these guys blocking most of the wall space?



I just want to be the first one to express my geeky delight at that Darth Vader mannequin. That is super cool.


Frank


----------



## yacht422




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18013293
> 
> 
> I was only addressing the special case of manniquins space somewhat away from the wall. Hard convex rather than concave surfaces should always be used.



thx for the response. however, one question remains: should the hard convex unit be empty or stuffed with adsorbing material? and, if we are diffusing, is the diameter important ( say, 12" vs: 6")[ X 8' long], or is the number of them a bigger factor. (so much to know, so little time)

walt


----------



## highlife

Hi, I am ready to address treatments now that my room is mostly complete. I have read many posts in this thread and have ideas of what and where to place treatments. I would like to confirm my thoughts with the experts in this thread! Here are a few pics so you can see my challenges. Behind the screenwall is a problem and I feel I will need to treat the entire wall area. I have not hooked up components yet so I dont know how bad it may be. So, besides the area behind the screen wall, would you recommend side wall or rear wall treatment? I am not considering ceiling as the height is an issue at only 80".


Many thanks for your thoughts and advice!


----------



## pepar




> Quote:
> Originally Posted by *highlife* /forum/post/18020529
> 
> 
> Hi, I am ready to address treatments now that my room is mostly complete. I have read many posts in this thread and have ideas of what and where to place treatments. I would like to confirm my thoughts with the experts in this thread! Here are a few pics so you can see my challenges. Behind the screenwall is a problem and I feel I will need to treat the entire wall area. I have not hooked up components yet so I dont know how bad it may be. So, besides the area behind the screen wall, would you recommend side wall or rear wall treatment? I am not considering ceiling as the height is an issue at only 80".
> 
> 
> Many thanks for your thoughts and advice!



Check the link in my sig for what I did behind my screenwall. Starts on pg 3 and then jumps to pg 23 with the addition of traps and a different screen.


Jeff


----------



## highlife

Thanks Jeff, I looked through your build site. The back of my screenwall is different in that it is not fully enclosed. I walk through the other side of the basement, behind a water heater, to get to that space. By blocking it off with say, triangle bass traps, I block off my entrance. The panels in front can be removed, but they are wedged in there pretty tight and would be a hassle to remove. The other corner behind that wall has a gas meter, which would limit the corner traps to about 36" high.


Questions:


1. Would it still be somewhat effective to trap the 36" of corner space (floor to gas meter)?

2. For the entrance side, could a thicker panel be placed, say behind the main speaker, for bass traps? Does linacoustic traps all frequencies?

3. How do you determine first reflection points on the sidewalls?

4. With the back of my room being open to a stairwell, is treatment effective?


Many thanks!


----------



## pepar




> Quote:
> Originally Posted by *highlife* /forum/post/18021358
> 
> 
> Thanks Jeff, I looked through your build site. The back of my screenwall is different in that it is not fully enclosed. I walk through the other side of the basement, behind a water heater, to get to that space. By blocking it off with say, triangle bass traps, I block off my entrance. The panels in front can be removed, but they are wedged in there pretty tight and would be a hassle to remove. The other corner behind that wall has a gas meter, which would limit the corner traps to about 36" high.
> 
> 
> Questions:
> 
> 
> 1. Would it still be somewhat effective to trap the 36" of corner space (floor to gas meter)?
> 
> 2. For the entrance side, could a thicker panel be placed, say behind the main speaker, for bass traps? Does linacoustic traps all frequencies?
> 
> 3. How do you determine first reflection points on the sidewalls?
> 
> 4. With the back of my room being open to a stairwell, is treatment effective?
> 
> 
> Many thanks!



At a certain point, you should do some acoustical measuring. But I think it is safe to add bass traps without doing that. Traps are best in corners, and don't only look at wall/wall corners. Floor and ceiling intersections with walls count as well. It is almost impossible to have too much bass trapping.

Here is a site with a LOT of test data for various materials typically used for absorbers. You will probably need to go somewhere like this to learn more about BASS TRAPS.


Calculate where to place absorbers for first reflection points? Ever play pool?


----------



## highlife

I was hoping to get some advice based on the photos I posted, not to become the resident expert on measuring frequency responses. I appreciate your reponses Jeff, don't get me wrong, but reading test data is not what I was looking for.


I believe I will need to cover the entire wall behind the screen with linacoustic, or something similar. The corners will be a challenge due to the reason previously stated, and I can do my best to place as many traps possible given the space. Still clueless on first reflection points on sidewalls, is there a basic distance formula front the front speakers? And rear walls, do they require sound absorption as well?


Thank you.


----------



## pepar




> Quote:
> Originally Posted by *highlife* /forum/post/18023504
> 
> 
> I was hoping to get some advice based on the photos I posted, not to become the resident expert on measuring frequency responses. I appreciate your reponses Jeff, don't get me wrong, but reading test data is not what I was looking for.
> 
> 
> I believe I will need to cover the entire wall behind the screen with linacoustic, or something similar. The corners will be a challenge due to the reason previously stated, and I can do my best to place as many traps possible given the space. Still clueless on first reflection points on sidewalls, is there a basic distance formula front the front speakers? And rear walls, do they require sound absorption as well?
> 
> 
> Thank you.



I would cover the entire wall, no actually the entire _cavity_, behind the wall. Beyond that, this is a place to come to learn how to fish, not to be given fish for free. There are members here who make and sell acoustical treatments that could probably ask you some simple questions and make recommendations to you. To continue with my metaphor, they will recommend which fish you buy from them and where (and how) to mount them.










The first reflection points are all about the locations of the speakers, the locations of the listeners and the distances. You could do the mirror/flashlight trick, or you could visualize pool shot angles.


Back wall? Depends on how the room is laid out and, more importantly, how it _measures._


----------



## Elill




> Quote:
> Originally Posted by *Elill* /forum/post/17983071
> 
> 
> Anyone know what the minimum recommended seating distance is from a BAD panel?
> 
> 
> Also if anyone can tell me the diameter of the holes that would be useful.



Anyone?


----------



## KERMIE




> Quote:
> Originally Posted by *KERMIE* /forum/post/18010408
> 
> 
> Anyone know at what Frequencies the average NON-AT screen reflects and lets pass through?



Guys, any help on this. Or should I ask, what Frequencies does the average screen reflect?


Thanks in advance


----------



## yacht422




> Quote:
> Originally Posted by *KERMIE* /forum/post/18026464
> 
> 
> Guys, any help on this. Or should I ask, what Frequencies does the average screen reflect?
> 
> 
> Thanks in advance



you might call your screen maker - they would have the best info on their own products(which may vary from mfg to mfg)


----------



## adammb

I have a room that is 22'x19'x7'5" and a fireplace in left rear of the room. I was planning on adding OC703 to the entire front wall and the side walls at 4.5' up on the wall. I am also going to have partially false soffits in which I will put cotton batting to absorb the bass. On top of that I have Auralex Lenrds that I will have on the front wall and I am not sure about the rear wall. Can someone please help me find a diagram of some sort of recommended placement. I know every room is different but it seems the more I read about this the more options I get. I can get 1",2", and 4" OC703 and will be placing this behind fabric panels made of GOM. I am going to be using this room for 96% home theater in an 11.1 setup using height channels. I am afraid since my ceiling is so low that I cannot put any treatment on the ceiling but I may change my mind down the road. Can someone have too many bass traps as I was going to make the stage and riser into bass traps.


Any and all help would be greatly appreciated. If you want some more details about my build my thread is Sweetwood 11.1.


Thanks


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/18017858
> 
> 
> thx for the response. however, one question remains: should the hard convex unit be empty or stuffed with adsorbing material? and, if we are diffusing, is the diameter important ( say, 12" vs: 6")[ X 8' long], or is the number of them a bigger factor. (so much to know, so little time)
> 
> walt



***************

Walt,

As luck would have it I'm finishing building TWO hemi-cylindrical diffusers (sometimes called polyfusers or 'those round things on the wall'). I've re-studied Toole's section in his latest book and communicated with his protege Dr Sean Olive a week ago about this very topic, before I made too many mistakes. . .


For the Harman listening room they used a 48" diameter Sonotube concrete forming tube and cut in in half (i.e. 180 degrees) with a radius of 24". They then applied Dynamat Xtreme car panel ( http://www.dynamat.com/products_auto...at_xtreme.html ) on the inside of the tube (concave part) to help stiffen it and reduce resonances. They filled the inside cavity with fibreglas and wrapped it in fabric and used cleats to hang it on the wall. You can see it on the rear walls of their room in this link:
http://seanolive.blogspot.com/2009/0...reference.html 


For my project I also chose a 48" diameter sonotube but used a 130 degree arc to get the right wall width coverage and radius extending into the room (called Sagitta) given my smaller room size and proximity to the listening positions. I used the following program to do "what if?" scenarios with various values for radius and degree arc to calculate the "sagitta," "chord length" and "circumfrence."

http://demonstrations.wolfram.com/Sa...othemAndChord/ 


I also used Dynamat on the interior and they filled the inside cavity with Owens Corning 701 Fibreglas wrapping it in plastic to prevent any loose fibres from entering the room. I made sure to mark a 6.5" line within the cavity which I used to mark where the fibreglass will start in order to create an air space between the wall and the start of the fibreglass, which equates to about 1/4 the wavelength of about 500Hz which I'm being conservative as estimating my Schroeder or transition frequency to be. I used 2-3 1"*2" studs on 'L' brackets to keep the fibreglass from springing back past the 6.5" line. Finally, I wanted a look more luxurious than cloth for a cover so got some red oak veneer with self adhesive glue already on it and all you need is a hot iron to melt the glue to the outside convex part of the tube. Be sure to sand the tube's exterior first to remove the wax so the veneer will bond with it.


The radius or Sagitta that extends into the room is only important if you wish to use it for bass trapping, which never hurts. The deeper the radius/sagitta the lower the bass trapping will work. Also the hard wood veneer will diffuse the mid/high frequencies.


Finally, if you are planning on using multiples of them on the same wall, you have to be careful to space them out and/or randomly place them and/or change the radius of each one.


Clear as mud, again?


----------



## kevinzoe




> Quote:
> Originally Posted by *adammb* /forum/post/18029908
> 
> 
> I have a room that is 22'x19'x7'5" and a fireplace in left rear of the room. I was planning on adding OC703 to the entire front wall and the side walls at 4.5' up on the wall. I am also going to have partially false soffits in which I will put cotton batting to absorb the bass. On top of that I have Auralex Lenrds that I will have on the front wall and I am not sure about the rear wall. Can someone please help me find a diagram of some sort of recommended placement. I know every room is different but it seems the more I read about this the more options I get. I can get 1",2", and 4" OC703 and will be placing this behind fabric panels made of GOM. I am going to be using this room for 96% home theater in an 11.1 setup using height channels. I am afraid since my ceiling is so low that I cannot put any treatment on the ceiling but I may change my mind down the road. Can someone have too many bass traps as I was going to make the stage and riser into bass traps.
> 
> 
> Any and all help would be greatly appreciated. If you want some more details about my build my thread is Sweetwood 11.1.
> 
> 
> Thanks



*****************
_"I was planning on adding OC703 to the entire front wall and the side walls at 4.5' up on the wall"_


Firstly, do you really want/need to absorp the entire front and side walls as it sounds like you'll make it too dead sounding, but to each his own . . . Secondly, use a minimum of 3"-4" thickness of your absorbing panels to act as a broadband absorber -- too thin and it'll just act as a treble attenuator throwing off the spectral balance that you paid dearly for from your beloved speakers.







Thirdly, the acoustical treatment should start 1 foot below your ear level and extend to 3 feet above your ear level, at the very least, which may or may not coincide with your "4.5' up on the wall" statement.


_"Can someone please help me find a diagram of some sort of recommended placement"_


Read Dr Floyd Toole's latest book to educate yourself before you waste money or build things incorrectly. He is as knowledgable and unbiased as any trusted source of info can be. The last chapter is where he lays out where different kinds of HT acoustical treatments ought to go - very helpful! Just so you know, he recommends absorption in the middle of the back and front walls with diffusion on either side of the absorption.


_"Can someone have too many bass traps . .. "_

Great question. You can guess at what the answer is if you ask any of the bass trap manufacturers . . . Since all small rooms suffer from bass modes you will need a combination of multiple subwoofers, bass traps, and parametric EQ to get the bass right. Typically the more bass traps you use the better the peaks and nulls become (i.e. lowering a peak and raising a null) while reducing ringing time and reverb time. BUT you will also need to turn up the bass volume. There are 2 other problems: (i) the bass traps don't magically stop working at say 500Hz which would be ideal, they keep on absorbing higher frequencies, albiet less effectively the higher up in freq you go, which only compounds the dead sounding room problem, and (ii) manufacturers don't always tell you how to properly set the bass traps up to max their effectiveness which may be self serving to get you to buy more of them. For resistive types made from fibreglass you need to pull them away from the wall by about 6-7" and have them extend as far into the room as possible to work at lower frequencies. Diaphragmatic bass traps work differently and work best when hung right on the wall where the air particle pressure is maximum - this obviously has a much smaller foot print. To counter the bass traps absorbing higher frequencies, try putting something hard like a sheet of plywood in front of them so that mid-higher frequencies will reflect off of it while bass frequencies won't even "see" the plywood.


hope this helps . . .


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/17589796
> 
> 
> I have two questions regarding primitive root (skyline) diffusers:
> 
> 
> 1) How would substituting round wooden dowels for square rods affect performance?
> 
> 
> 2) How would mounting these dowels (or rods) on a curved surface, such as a large polycylindrical diffuser, affect performance?
> 
> 
> Thanks,
> 
> John



************************

John - interesting questions you pose.


Question 1: I would expect that replacing square with round wooden pieces will significantly add to the absorption of the diffuser due to the additional open spaces between round shaped dowels. I don't think you want to raise the absorption level of a diffuser, otherwise you'd have put an absorber there instead of a diffuser . . . If round shapes would have worked, then I would surmise that RPG and others would have used it.


Question 2: If you are going to use a hemicylindrical diffuser and attach round dowels perpendicular to the hemicyclindrical's surface, then you are in theory creating a 2 dimensional diffuser; if the hemicylindrical is oriented vertically then it diffuses sound horizontally, while the round dowels are oriented horizontally and would diffuse sound in the vertical plane. Nice idea but I think a better 2D diffuser is the Skyline based on whatever prime number is large enough to cover your desired wall space.


Have you used the following Skyline calculator? I've found it to be the best, but there could be others . . .

http://www.oliverprime.com/prd.php 


If you want some help in using it, PM me.


Hope this helps some . . .


----------



## maxfli

Hi all,


I have (2) sets of triangles of JM 814 2" that are 17" x 17" x 24" that will fill an 8' tall area. I originally planned to use these a superchunk trap in the corners of my stage.


Because I have limited space is this area due to pillars that are built in the corner and large subwoofers, I am considering building a membrane trap instead. Question is: Can I use these triangles in a membrane trap and place a 3/8" mdf sheet in front of them leaving a 1/4 to 1/2" or so between the JM 814 triangles and the mdf sheet? Will this be an effective trap for the corner?


All other diagrams I've seen so far show a 2" flat OC 703/JM 814 behind the mdf sheet, but no more material that the 2" thickness.


Thanks,

Max


----------



## Terry Montlick

You cannot make an effective reasonably wide-band membrane trap with this heavy a panel/membrane. Think in terms of paper thickness, not MDF thickness.







I will often design with faced fiberglass, with the paper facing outward. This reflects highs and boosts lows a bit (though not uniformly).


But if there is no reason not to absorb high frequencies over the very limited surface area of your corner trap (e.g., your room is currently in perfect balance for high frequencies), forget about adding a membrane.


----------



## Dennis Erskine

There is a plastic sheeting with an adhesive back...comes in rolls. It is used by contractors over carpet to prevent soiling the carpet during construction. This makes a good membrane. You can also use 3mil or 6mil plastic sheeting as well.


----------



## maxfli

Thank you both for your replies. I was looking at the 'Resonant Membrane, Flat Panel Traps' section half way down the page of this link.

http://home.comcast.net/~thomasw-2/S...ndEQpage9.html 


The picture with reference to Ethan's website shows a plywood front and then discusses aborption to 1/8" = 150 Hz, 1/4" = 110 Hz, and 3/8" = 87 Hz based on the thickness of the plywood. Is this design outdated or just not as effective?


Also, I should probably know better than to provide a link from a comcast related site.


----------



## 3fingerbrown




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18039377
> 
> 
> You cannot make an effective reasonably wide-band membrane bass trap with this heavy a panel/membrane. Think in terms of paper thickness, not MDF thickness.
> 
> 
> 
> 
> 
> 
> 
> I will often design with faced fiberglass, with the paper facing outward. This reflects highs and boosts lows a bit (though not uniformly).



Terry, I have a question about your response that I posted in my build thread "3FB's Foreclosure Home Theater". I'd be interested in your thoughts or anyone else's thoughts. Thanks.


----------



## Terry Montlick




> Quote:
> Originally Posted by *maxfli* /forum/post/18040233
> 
> 
> Thank you both for your replies. I was looking at the 'Resonant Membrane, Flat Panel Traps' section half way down the page of this link.
> 
> http://home.comcast.net/~thomasw-2/S...ndEQpage9.html
> 
> 
> The picture with reference to Ethan's website shows a plywood front and then discusses aborption to 1/8" = 150 Hz, 1/4" = 110 Hz, and 3/8" = 87 Hz based on the thickness of the plywood. Is this design outdated or just not as effective?
> 
> 
> Also, I should probably know better than to provide a link from a comcast related site.



Yes, those numbers look quite plausible for the 3 1/2" depth which is specified. But remember that these are narrow-band absorbers, tuned to one specific frequency. That's why I qualified my reply with the words "reasonably wide-band." A narrow-band absorber will absorb little outside of its narrow tuned frequency. It can be effective for a single problematic room mode whose frequency you know, but not as a general-purpose device.


----------



## Spaceman

I just received my microsuede samples from ATS Acoustics and it is definately the nicest suede I've received so far. However, I was under the impression that it would be acoustically transparent, or semi-transparent. Using the ever-popular blow test, I failed miserably. Was I incorrect in thinking this was supposed to have a more open weave? Is it supposed to be used as a reflective surface or over an absorptive one?


I have samples from other companies that are definately more open, but they don't look as nice. Has anyone used this material before?


----------



## pepar




> Quote:
> Originally Posted by *Spaceman* /forum/post/18057787
> 
> 
> I just received my microsuede samples from ATS Acoustics and it is definately the nicest suede I've received so far. However, I was under the impression that it would be acoustically transparent, or semi-transparent. Using the ever-popular blow test, I failed miserably. Was I incorrect in thinking this was supposed to have a more open weave? Is it supposed to be used as a reflective surface or over an absorptive one?
> 
> 
> I have samples from other companies that are definately more open, but they don't look as nice. Has anyone used this material before?



Microfiber suede is usually associated - at least in my mind - with SEATS.


----------



## Spaceman

I agree, as I have it on my own loveseat and sofa. However, I was in a demo theater recently that had it on the wall and it looked great. After seeing it for sale by many acoustic panel companies, I started collecting samples. The stuff that looks good seems too thick and the thinner stuff looks terrible. I just thought it might be a nice alternative to GOM.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Spaceman* /forum/post/18063009
> 
> 
> I agree, as I have it on my own loveseat and sofa. However, I was in a demo theater recently that had it on the wall and it looked great. After seeing it for sale by many acoustic panel companies, I started collecting samples. The stuff that looks good seems too thick and the thinner stuff looks terrible. I just thought it might be a nice alternative to GOM.



Even though it might have more HF absorption than GOM, you have to consider whether that is a good or a bad feature for your particular use. I wouldn't use it for a speaker grill...........................


----------



## yacht422

Walt here, with a bass trap question. Assume a round tube, 12" diameter x four feet long, to be filled with rock wool. Does one "stuff the tube" with no open inside space, or does there need to be an void of "x" inches in order to be effective?

Walt


----------



## Ethan Winer

Neither - for good results you need a tube that's at least 18 inches in diameter or larger. The tube should be thin cardboard, stuffed fully with insulation. Or don't use a tube at all. It's the insulation that does all the absorbing!


--Ethan


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/18067417
> 
> 
> Walt here, with a bass trap question. Assume a round tube, 12" diameter x four feet long, to be filled with rock wool. Does one "stuff the tube" with no open inside space, or does there need to be an void of "x" inches in order to be effective?
> 
> Walt



Walt - as per Toole's Toome, he recommends a depth of at least 12 inches so that could mean starting with a 24" diameter tube cut in half for a 180degree arc to provide the 12" radius. Just like other bass traps, an air space between the wall and the back of the tube helps lower the LF bass trap absorption performance, provided it's full of fibreglass etc. You can elect to hang the tube away from the wall to create the air space OR do what I suggested which is to use 1"*2" wood pieces to hold back the insulation from springing towards the wall if the tube is hung flush with the wall.


Obviously there are many other ways to get to a 12" depth meaning using larger diameter tubes to start with and smaller arc angles, but I already sent you some info on that . . . I don't mind sharing it with others if interested . . .


----------



## adammb

I am interested. I am mounting half columns at a diameter of 16-18" on the walls and am thinking of adding some cotton batting or insulation to the back of them. More info would be awesome.


----------



## yacht422




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18070323
> 
> 
> Walt -
> 
> 
> 
> Quote:
> as per Toole's Toome, he recommends a depth of at least 12 inches so that could mean starting with a 24" diameter tube cut in half for a 180degree arc to provide the 12" radius. Just like other bass traps, an air space between the wall and the back of the tube helps lower the LF bass trap absorption performance, provided it's full of fibreglass etc. You can elect to hang the tube away from the wall to create the air space OR do what I suggested which is to use 1"*2" wood pieces to hold back the insulation from springing towards the wall if the tube is hung flush with the wall.
> 
> 
> 
> 
> Obviously there are many other ways to get to a 12" depth meaning using larger diameter tubes to start with and smaller arc angles, but I already sent you some info on that . . . I don't mind sharing it with others if interested . . .
Click to expand...


kevin: thx for the reponse, but, that is not the answer to the question.

is a 12" tube stuffed with rockwool effective, or, does there need to be a void in the center? i recognize that the 'hemi' you sent info about has an opening for air. that would be a different application for me.

again, my thanks

walt


----------



## kevinzoe




> Quote:
> Originally Posted by *adammb* /forum/post/18070623
> 
> 
> I am interested. I am mounting half columns at a diameter of 16-18" on the walls and am thinking of adding some cotton batting or insulation to the back of them. More info would be awesome.



Adammb - If you use say an 18" diameter column (tube?), then even with a 180degree arc your radius is only 9" (i.e. radius = half the diameter) which is too shallow a depth according to Dr Floyd Toole's research. With the tube only extending into the room by 9" at it's deepest point it's not likely to work as low into the bass region as you'd like . . . Can you get a larger tube to start with or live with the column intruding into the room a bit more?


If you can't then here's the data you'll need to make some decisions around your column/tube. For an 18" diameter tube, the following represents (i) the arc angle in degrees, (ii) the arc circumfrance in inches, (iii) the distance it sticks into the room in inches, (iv) the chord length across the wall from one edge of the arc to the other in inches.


90 / 14 / 2.6 / 12.7

120 / 18.8 / 4.5 / 15.6

150 / 23.6 / 6.7 / 17.4

180 / 28.3 / 9 / 18


I hope you don't mind the 30degree increments for the data. For smaller tubes like your's I'd suggest going with a 180degree arc for max benefit.


Hope this answers your question. Do you know how the make the rest of the hemicylindrical tube?


----------



## giomania




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18073366
> 
> 
> Adammb - If you use say an 18" diameter column (tube?), then even with a 180degree arc your radius is only 9" (i.e. radius = half the diameter) which is too shallow a depth according to Dr Floyd Toole's research. With the tube only extending into the room by 9" at it's deepest point it's not likely to work as low into the bass region as you'd like . . . Can you get a larger tube to start with or live with the column intruding into the room a bit more?
> 
> 
> If you can't then here's the data you'll need to make some decisions around your column/tube. For an 18" diameter tube, the following represents (i) the arc angle in degrees, (ii) the arc circumfrance in inches, (iii) the distance it sticks into the room in inches, (iv) the chord length across the wall from one edge of the arc to the other in inches.
> 
> 
> 90 / 14 / 2.6 / 12.7
> 
> 120 / 18.8 / 4.5 / 15.6
> 
> 150 / 23.6 / 6.7 / 17.4
> 
> 180 / 28.3 / 9 / 18
> 
> 
> I hope you don't mind the 30degree increments for the data. For smaller tubes like your's I'd suggest going with a 180degree arc for max benefit.
> 
> 
> Hope this answers your question. Do you know how the make the rest of the hemicylindrical tube?



Great Info. I put it into a spreadsheet for my sanity, but cannot upload .xls files. I pasted it in, but it was all messed up.


Tube Diameter = 18"


Arc Angle (Degrees)

Circumference of Arc (inches)

Distance from wall when flush-mounted (inches)

Total width of circumference (inches)


90 14 2.6 12.7

120 18.8 4.5 15.6

150 23.6 6.7 17.4

180 28.3 9 18


If you have the formulas, I could plug them in so that anyone can plug in their tube diameter and it would automatically calculate the data. If you are interested, please look to see if the labels make sense to you.


Mark


----------



## kevinzoe




> Quote:
> Originally Posted by *giomania* /forum/post/18076522
> 
> 
> Great Info. I put it into a spreadsheet for my sanity, but cannot upload .xls files. I pasted it in, but it was all messed up.
> 
> 
> Tube Diameter = 18"
> 
> 
> Arc Angle (Degrees)
> 
> Circumference of Arc (inches)
> 
> Distance from wall when flush-mounted (inches)
> 
> Total width of circumference (inches)
> 
> 
> 90 14 2.6 12.7
> 
> 120 18.8 4.5 15.6
> 
> 150 23.6 6.7 17.4
> 
> 180 28.3 9 18
> 
> 
> If you have the formulas, I could plug them in so that anyone can plug in their tube diameter and it would automatically calculate the data. If you are interested, please look to see if the labels make sense to you.
> 
> 
> Mark



*************

Mark - glad the info was helpful. I use a great math website called Wolfram and here is a link to the app that will do all the calculations for you:
http://demonstrations.wolfram.com/Sa...othemAndChord/ 


You'll have to download the demo s/w and then you need only to specify what the tube radius is and the arc in degrees and the other variables are automatically calculated.


You'll note that the terms "Sagitta" and "Chord Length" are the math terms for what you called "Distance from wall when flush-mounted" and "Total width of circumference" respectively.


I started off with a 48" diameter (24" radius) and charted all the values from 90-180 degrees for planning purposes. I then settled on 130degree arc for my room's side walls (one hemicylindrical diffuser per side wall).


----------



## adammb

So your saying I would be better to do a larger diameter tube and not use a complete half. So in essence it would be about 10-12 out but have a radius larger than 10-12 inches. So starting with a 24" and using less than half of it and having it come out 12" but still being about a 20" width? Then stuffing it with cotton or insulation and leaving a gap between the wall and the insulation?


----------



## kevinzoe




> Quote:
> Originally Posted by *adammb* /forum/post/18076855
> 
> 
> So your saying I would be better to do a larger diameter tube and not use a complete half. So in essence it would be about 10-12 out but have a radius larger than 10-12 inches. So starting with a 24" and using less than half of it and having it come out 12" but still being about a 20" width? Then stuffing it with cotton or insulation and leaving a gap between the wall and the insulation?



Sounds about right. Just to be clear, if you use a small radius hemicylindrical diffuser with a hard outer layer, it will diffuse the mid/hi frequencies and only effect the upper bass (providing it's stuffed with fibreglass etc). (The radius distance is what determines how low the absorption will work to.) So what's wrong with only affecting 2/3rds of the freq range you ask? It throws off the spectral balance of your speakers you fell in love with. A smaller radius tube will work IF you put some seperate bass trapping above or below it if the intrusion into the room isnt to your liking. . .


By the way, where are you placing these columns and is it for HT for 2-channel stereo music?


----------



## adammb

Here is my plan.


Two columns down the sides of the wall spaced evenly and two columns on the rear wall about 4-5 in from the sides. I also have some auralex megalenrds that I will use in the front corners.


I am also contemplating to have false soffits that come out about 16" and stuffing them with cotton batting and then placing paper backing in front of them so the highs do not get absorbed.


For more than bass I was going to have panels in between the pillars that were filled with 3" cotton batting but not the full size in between the pillars.


My room is 19x22x7'4". If you want to take a closer look at my build it is the sweetwood 11.1 thread.


I have also been trying to figure out how to place my seating depending on the bass wave zones. Could you direct me to a place to determine this?


How does that sound?


----------



## Hughman

I stupidly started a new thread regarding improving RT60 times in my room but will continue on here in this thread. In summary my room is about 2500sqft which I covered with fabric panels a couple years ago. During that time period I experimented with a few acoustic treatments but felt the overall presentation coupled with the fabric was a too dead sounding room. Returning to the issue I measured the RT60 times and posted the graphs in the initial thread here http://www.avsforum.com/avs-vb/showt...093&highlight= 


The past couple days I removed the panels and purchased a case of 2" OFI-48 FSK insulation (Ottawa Fiber) which best approximated the frequency specific absorption values I felt I required. After a day of experimenting with placement of the acoustic insulation I settled on just two 2'x4' pieces placed horizontally touching the ceiling on the left and right front side walls adjacent to the screen. After initially loading up the room with the acoustic panels and measuring about between 2 and 2.5ms across the board and listening to the result it was clear, in an underwater way, the room and music were way too dead for my liking so I decided to try to target RT60 in the mid 3ms range which the results are below, along with an impulse response graph.


Just a note that with a room of this relatively small size the effective RT60 is far from a constant value and easily influenced by typical usage, reclining my 6 theater chairs has a fairly dramatic effect on the overall RT60 as does adding a few people to the arena. As such the multiple conditions the theater will be used should be accounted for and factored into the target RT60.


Though I loved the look of the theater with the fabric on the walls I'll now be leaving the walls bare except for the black velvet on the ceiling and front wall area.


----------



## pepar

Quite a difference in the measurements. How does it _sound_?


Jeff


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18083402
> 
> 
> Quite a difference in the measurements. How does it _sound_?
> 
> 
> Jeff



Overall I like the balance better for both mc movies and 2-channel music, the upper frequencies have a far more natural ting to them now and any recorded high frequency room ambiance is more apparent as well. A great benefit is also the fleshing out of the rear channels, removing the wall fabric has really improved the sense of rear space and the entire presentation is more enveloping. I'll be picking away at a few areas over the next month or so but so far I'm pleased. My wife is pissed however.


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18083501
> 
> 
> Overall I like the balance better for both mc movies and 2-channel music, the upper frequencies have a far more natural ting to them now and any recorded room ambiance is more apparent as well. A great benefit is also the fleshing out of the rear channels, removing the wall fabric has really improved the sense of rear space and the entire presentation is more enveloping. I'll be picking away at a few areas over the next month or so but so far I'm pleased. My wife is pissed however.



Looks like the bottom got cleaned up a lot. My experience is that doing that removes a "veil" that masks the mids and highs, and produces the differences in balance and envelopment you noticed.


The wife thing, too, is not unusual. You know, don't you, that they just .. don't .. understand.


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18083516
> 
> 
> Looks like the bottom got cleaned up a lot. My experience is that doing that removes a "veil" that masks the mids and highs, and produces the differences in balance and envelopment you noticed.
> 
> 
> The wife thing, too, is not unusual. You know, don't you, that they just .. don't .. understand.



Actually my wife is pretty cool with anything I do down here. Regarding the "veil", I watched Surveillance last night and for the first time for a long time was completely mesmerized with the sound, I also threw on Kung Fu Panda which I use for reference purposes and that, not too surprisingly, sounded outstanding as well. It would seem that with a more consistent RT60 individual sounds are more fleshed out and image with more body almost like you can sense a front and a back to it and overall a much better sense of space between them.


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18083615
> 
> 
> Actually my wife is pretty cool with anything I do down here. Regarding the "veil", I watched Surveillance last night and for the first time for a long time was completely mesmerized with the sound, I also threw on Kung Fu Panda which I use for reference purposes and that, not too surprisingly, sounded outstanding as well. It would seem that with a more consistent RT60 individual sounds are more fleshed out and image with more body almost like you can sense a front and a back to it and overall a much better sense of space between them.



I'm sure that overall consistent (ly good) reverb times help, but I vote for the cleaned up LF ringing as the main dif in your sound quality.


Jeff


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18083649
> 
> 
> I'm sure that overall consistent (ly good) reverb times help, but I vote for the cleaned up LF ringing as the main dif in your sound quality.
> 
> 
> Jeff



Astute observation on the LF ringing. With the left over insulation I fashioned a quick and dirty 8" thick trap and placed it in the back left corner. Here's a the updated LF waterfall which does show an improvement.


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18083745
> 
> 
> Astute observation on the LF ringing. With the left over insulation I fashioned a quick and dirty 8" thick trap and placed it in the back left corner. Here's a the updated LF waterfall which does show an improvement.



Still too much ringing way down low. You need more bass traps and to reach that low, they'd need to be biguns. Along with the peaks (ringing), they would reduce the nulls you see in the LF response.

http://www.peparsplace.com/Pg_23.htm 


Play some music - jazz seems to work best IMO - with a walking bass run. Listen for louder and softer - and missing - notes. When you hear all notes equally, you are done.


Jeff


----------



## yacht422

walt here. i asked this question a while back and received no responses.. perhaps because there IS no answer. however, i'll try one more time.

we cover f/g absorbing units with gom, a known material.

what happens if we use either plastic or wire screening material in lieu of the gom?

i have triangle (superchunk) f/g stacks in the rear corners(floor to ceiling), covered w/gom. if i covered with screening, would there be a change in the mid/hi reflection? the lows would not be impacted, but the other freq's??

again, this may be uncharted territory, but somehow i doubt it.

thx

walt


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18083827
> 
> 
> Still too much ringing way down low. You need more bass traps and to reach that low, they'd need to be biguns.
> 
> http://www.peparsplace.com/Pg_23.htm
> 
> 
> Jeff



I'm not too sure how to read the waterfall charts what areas do you see the ringing problem, below 30hz?


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18083852
> 
> 
> I'm not too sure how to read the waterfall charts what areas do you see the ringing problem, below 30hz?



Yes, and it is the most difficult to reduce. Lots of bass trap volume is needed to do it.


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/18083849
> 
> 
> walt here. i asked this question a while back and received no responses.. perhaps because there IS no answer. however, i'll try one more time.
> 
> we cover f/g absorbing units with gom, a known material.
> 
> what happens if we use either plastic or wire screening material in lieu of the gom?
> 
> i have triangle (superchunk) f/g stacks in the rear corners(floor to ceiling), covered w/gom. if i covered with screening, would there be a change in the mid/hi reflection? the lows would not be impacted, but the other freq's??
> 
> again, this may be uncharted territory, but somehow i doubt it.
> 
> thx
> 
> walt



Chicken wire???


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18083865
> 
> 
> Yes, and it is the most difficult to reduce. Lots of bass trap volume is needed to do it.



The 40hz null I'm pretty much pretty stuck with but below that I'm not going to even attempt to attack that with insulation as as you say it will take a lot of cubic feet which, I'm convinced will have likely have more than deleterious effects above 40hz. I suppose I could make my riser into a Helmholtz resonator with a frequency centered around the 20hz but I rather enjoy the free chair and body vibrating anti-nodes down low.


----------



## yacht422




> Quote:
> Originally Posted by *pepar* /forum/post/18083869
> 
> 
> 
> 
> Quote:
> Chicken wire???
Click to expand...


no, screening such as for screen doors, or (here in florida) lanai's.(pool cages)

walt


----------



## glaufman

On the waterfalls, what I see is a much more consistent decay time, not so much improvement of the really bad ringing at the very low end. I think pulling in the 500Hz might have been more significant (as shown on the RT60)...

BTW, with REW, at least in the current version, you can't really trust the waterfall plots unless you've got the frequency axis in LOG mode, you're in LIN mode...


----------



## glaufman




> Quote:
> Originally Posted by *Hughman* /forum/post/18083940
> 
> 
> The 40hz null I'm pretty much pretty stuck with but below that I'm not going to even attempt to attack that with insulation as as you say it will take a lot of cubic feet which, I'm convinced will have likely have more than deleterious effects above 40hz. I suppose I could make my riser into a Helmholtz resonator with a frequency centered around the 20hz but I rather enjoy the free chair and body vibrating anti-nodes down low.



Actually, IF you were to put in enough broadband absorption to tame


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18083940
> 
> 
> The 40hz null I'm pretty much pretty stuck with but below that I'm not going to even attempt to attack that with insulation as as you say it will take a lot of cubic feet which, I'm convinced will have likely have more than deleterious effects above 40hz. I suppose I could make my riser into a Helmholtz resonator with a frequency centered around the 20hz but I rather enjoy the free chair and body vibrating anti-nodes down low.



You seem to have a good grasp of the problem and the associated pluses and minuses of attacking it.


I hear ya on the 20Hz node!


Jeff


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/18083952
> 
> 
> no, screening such as for screen doors, or (here in florida) lanai's.(pool cages)
> 
> walt



That would certainly pass bass frequencies.


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/18084093
> 
> 
> Actually, IF you were to put in enough broadband absorption to tame


----------



## Elill

Greg - I might have missed it, but what type of fabric did you have up before you took is all down?


----------



## Hughman




> Quote:
> Originally Posted by *glaufman* /forum/post/18084093
> 
> 
> Actually, IF you were to put in enough broadband absorption to tame


----------



## yacht422




> Quote:
> Originally Posted by *Hughman* /forum/post/18084457
> 
> 
> 
> 
> Quote:
> A few years ago I attempted to tame the 31hz peak by purchasing a few bundles of the OFI-48. After weeks of experimentation the only remedy of any significance was to create a wall of absortion floor to ceiling about 8 feet out from the back wall (approx 1/4 wavelength) of the offending frequencies. This was prior to the two rows of seating I presently have which now makes implementation of the same solution a rather unpleasant movie-going experience for those in the back row.
Click to expand...


so - - -is the point that we go to the pros for a mega-buck solution?

ASC makes what seems to be an industry recognized product (tube trap) that professes to control the lowest freq.'s. perhaps gik and ethan winers companies have products as well. there is a link earlier in this thread that connects to a _diy_ ASC imitation - no idea if it is as effective as the real thing.

perhaps when kevinzoe logs back on he will have some insights.

walt


----------



## yacht422




> Quote:
> 
> 
> 
> Quote:
> Originally Posted by *pepar* /forum/post/18084132
> 
> 
> That would certainly pass bass frequencies.
Click to expand...


yes, but, would it be more reflective than gom? my guess is that it would, but, how to test?

as stated in my earlier post, i would hope that someone in this _ether_ world would have the answer.

however, my thanks to pepar!

and now to my man cave for some viewing.

walt


----------



## pepar




> Quote:
> Originally Posted by *yacht422* /forum/post/18084967
> 
> 
> yes, but, would it be more reflective than gom? my guess is that it would, but, how to test?
> 
> as stated in my earlier post, i would hope that someone in this _ether_ world would have the answer.
> 
> however, my thanks to pepar!
> 
> and now to my man cave for some viewing.
> 
> walt



One of the acousticians on the thread might have an answer. Otherwise I only know that while there are websites that give test results for commonly used materials, I don't think that door screen is one of them. Is there a reason why you can't/don't want to use what many others have used - GOM?


----------



## SierraMikeBravo

I am always at a loss as to why everyone always assumes that "pros" cost mega-bucks? Some pros can be had for $500 for giving advice to do exactly what you you are looking for, and considering how much went into a room cost and time wise...will that honestly break the bank to bring your room alive! The best answer I can give in that arena is ask a pro how much they cost, get references (do they know what they are doing), and then decide if your time and unanswered questions are worth the cost of the technician.


There are often easier solutions than slapping up tons of fiberglass to tame bass modes. A good place to start is to determine if a peak or null is actually due to a bass mode. Then proceed from there.


I am not familiar with OFI-48, but...if it is not unlike other fiberglass insulation, it works best as a frictional absorber. Understanding how the stuff we breathe is behaving in a theater room is of great benefit to determine how to treat your room.


To answer your question regarding screen or plastic...best answer I can give is give it a try! Not much spent if it turns out to be a failed experiment...and you're right....just about everything you can almost think of has been tried at one time or another. It's not often the materials alone...it's the combination of such materials that may or may not make the difference. Best wishes!


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18085030
> 
> 
> 
> There are often easier solutions than slapping up tons of fiberglass to tame bass modes. A good place to start is to determine if a peak or null is actually due to a bass mode. Then proceed from there.



What else would cause a null?


Jeff


----------



## Hughman




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18085030
> 
> 
> I am not familiar with OFI-48, but...if it is not unlike other fiberglass insulation, it works best as a frictional absorber. Understanding how the stuff we breathe is behaving in a theater room is of great benefit to determine how to treat your room.



The OFI-40/48 material is made by Ottawa Fiber and specs as the equivalent of OC 700 series. The product sheet for the 48 FSK board is below.

http://rds.yahoo.com/_ylt=A0geu.03Gm...-factsheet.pdf


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/18085047
> 
> 
> What else would cause a null?
> 
> 
> Jeff




Technically you are correct. A null is the result of a mode. I should revise that and say if not a null, what else is causing a loss of SPL at a certain frequency...or a dip. Could be several things. First thing to do though is to see if it is a null at that listening position which can be verified just by calculating the modes for the room.


Hughman...thanks for the info.


----------



## kevinzoe




> Quote:
> Originally Posted by *yacht422* /forum/post/18084938
> 
> 
> so - - -is the point that we go to the pros for a mega-buck solution?
> 
> ASC makes what seems to be an industry recognized product (tube trap) that professes to control the lowest freq.'s. perhaps gik and ethan winers companies have products as well. there is a link earlier in this thread that connects to a _diy_ ASC imitation - no idea if it is as effective as the real thing.
> 
> perhaps when kevinzoe logs back on he will have some insights.
> 
> walt



**************

With such a low freq peak, the resistive-type bass traps aren't likely to be the best solution. I think a better alternative would be to use a combination of multiple subwoofers and parametric eq. Then if you still need trapping a membrane/diaphragmatic or helmholtz type would be better suited.


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18086683
> 
> 
> **************
> 
> With such a low freq peak, the resistive-type bass traps aren't likely to be the best solution. I think a better alternative would be to use a combination of multiple subwoofers and parametric eq. Then if you still need trapping a membrane/diaphragmatic or helmholtz type would be better suited.



1. Speaker position.

2. Listener position.

3. Acoustical treatments.

4. Electronic correction.


Many/Most of us do not have the option of #2 as they are usually dictated by room size and layout, seats present, display size and location, etc. In other words ... other factors.


For #1, many times subs can be moved around, but the factors restricting #2 also many times limit #1.


More should be done with #3 but it sometimes runs afoul of aesthetics ... and even room space limitations. Nonetheless, acoustical treatments of room modes can make a HUGE improvement. Certainly moving a sub so as to not excite a particular room mode makes sense - and is free - but the mode is not eliminated .. and other modes are not addressed. Bass traps reduce the reflections that are the cause of room modes ... all of them. Install enough of the right traps and the room's LF response smooths out and sounds amazing. Unfortunately, most people are so unfamiliar with smooth, flat bass that they feel something is missing when they hear it. (But that's another subject entirely.)


Number four is the icing on the cake, but I would strongly recommend that something like the SVS AS-EQ1 (and multiple subs) be used to correct LF response. Simple equalizers don't come close to the improvements from this piece of gear. And it improves over all of the listening positions, not just one. And it works partly in the time domain so it can help with ringing. Electronic correction is not a substitute for acoustical treatments, but it will improve just about any room/system.


Just my $.02.


Jeff


----------



## kevinzoe

***********

Hughman - As RT60 is typically associated with concert halls and generally large volume buildings, have you tried measuring a RT20 or RT30 should be a more realistic measurement for the home-based room size? It might be interesting to compare a RT20/30 measurement with your previous RT60 . . .


Just a thought . . .



> Quote:
> Originally Posted by *Hughman* /forum/post/18082967
> 
> 
> I stupidly started a new thread regarding improving RT60 times in my room but will continue on here in this thread. In summary my room is about 2500sqft which I covered with fabric panels a couple years ago. During that time period I experimented with a few acoustic treatments but felt the overall presentation coupled with the fabric was a too dead sounding room. Returning to the issue I measured the RT60 times and posted the graphs in the initial thread here http://www.avsforum.com/avs-vb/showt...093&highlight=
> 
> 
> The past couple days I removed the panels and purchased a case of 2" OFI-48 FSK insulation (Ottawa Fiber) which best approximated the frequency specific absorption values I felt I required. After a day of experimenting with placement of the acoustic insulation I settled on just two 2'x4' pieces placed horizontally touching the ceiling on the left and right front side walls adjacent to the screen. After initially loading up the room with the acoustic panels and measuring about between 2 and 2.5ms across the board and listening to the result it was clear, in an underwater way, the room and music were way too dead for my liking so I decided to try to target RT60 in the mid 3ms range which the results are below, along with an impulse response graph.
> 
> 
> Just a note that with a room of this relatively small size the effective RT60 is far from a constant value and easily influenced by typical usage, reclining my 6 theater chairs has a fairly dramatic effect on the overall RT60 as does adding a few people to the arena. As such the multiple conditions the theater will be used should be accounted for and factored into the target RT60.
> 
> 
> Though I loved the look of the theater with the fabric on the walls I'll now be leaving the walls bare except for the black velvet on the ceiling and front wall area.


----------



## SierraMikeBravo

I would also consider the Audyssey SubEQ. The designers of the SVS EQ were of course Audyssey. Trust me when I tell you that Audyssey saved the best elements for their product. The prices between the two are very comparable.


----------



## Hughman




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18087571
> 
> 
> ***********
> 
> Hughman - As RT60 is typically associated with concert halls and generally large volume buildings, have you tried measuring a RT20 or RT30 should be a more realistic measurement for the home-based room size? It might be interesting to compare a RT20/30 measurement with your previous RT60 . . .
> 
> 
> Just a thought . . .



No I haven't plotted RT20 or RT30 I just used the RT60 tab in REW, is this a new development on the leading edge of typical HT sized room acoustics? A quick search for RT20 on this entire site shows your post is the very first mention of it.


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18088246
> 
> 
> I would also consider the Audyssey SubEQ. The designers of the SVS EQ were of course Audyssey. Trust me when I tell you that Audyssey saved the best elements for their product. The prices between the two are very comparable.



I do trust you, but think you might be exaggerating a bit.










Using the Audyssey Pro balanced mic would be nice - as I have one - but it's not a deal breaker. Ditto MultEQ Pro. The Pro kits themselves are expensive and that needs to be factored in to the "total cost of ownership" for those who don't already own one. At least there are no license costs to use Pro on the Audyssey Subwoofer Equalizer.


Most people do not need to setup two subs in two independent systems.


Beyond those differences, they are identical.










Jeff


----------



## VirTERM

I finally finished reading this thread from the very beginning. I must say, I was changing my mind (planned approach) several times, as there is lots of contradictions and different opinions










At this point, I decided to start with treating first reflection points (side walls first) and the back of the room (second row is near the back wall). I am still not sure if I want to put any panels behind my speakers (front wall), but most likely yes. I am still shopping around, but definitely I will use 4" for the back wall and probably 2" for the side walls. At this point my room is not treated at all, just the carpet on the floor.

Here is the output from REW, the blue line shows measurements without subwoofer turned on and the brown one shows mains with a sub. Should I be drawing any conclusion from these measurements? I see several peaks and nulls







....


Thanks,

Wojtek


----------



## SierraMikeBravo

Hi Jeff,


Mic sensitivity is quite a bit different between the two as well, and after talking with Audyssey repeatedly over this issue, there are significant differences worthy of the minute cost difference...and, IMHO, SubEQ just looks nicer...but I digress







. In addition, the setup for the SubEQ is so easy, I generally don't ask much at all to install it. Takes me roughly an hour just for the SubEQ if I don't do secondary verification or any other work. There are distinct similarities, but for an extra few bucks, I would lean toward the SubEQ myself for the additional features.. Just personal preference. Nothing more.


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18089403
> 
> 
> Hi Jeff,
> 
> 
> Mic sensitivity is quite a bit different between the two as well, and after talking with Audyssey repeatedly over this issue, there are significant differences worthy of the minute cost difference...and, IMHO, SubEQ just looks nicer...but I digress
> 
> 
> 
> 
> 
> 
> 
> . In addition, the setup for the SubEQ is so easy, I generally don't ask much at all to install it. Takes me roughly an hour just for the SubEQ if I don't do secondary verification or any other work. There are distinct similarities, but for an extra few bucks, I would lean toward the SubEQ myself for the additional features.. Just personal preference. Nothing more.



You're probably right about the calibrated Pro mic being better to use for the subwoofer setup. When I overlayed a Pro calibration on my system, I thought I heard an improvement in the LF and Mains/SW integration. Some of that is undoubtedly due to the better (and individually calibrated) mic.


Jeff


----------



## yacht422




> Quote:
> Originally Posted by *pepar* /forum/post/18085025
> 
> 
> One of the acousticians on the thread might have an answer. Otherwise I only know that while there are websites that give test results for commonly used materials, I don't think that door screen is one of them.
> 
> 
> 
> Quote:
> Is there a reason why you can't/don't want to use what many others have used - GOM?
Click to expand...


no, not really. it is a question of the intellectual type - i covered my treatments with gom, but, the superchunks covered in screen might have added to room reflections, (screen vs:gom) . i was hoping for additional insights, but, this is somewhat arcane, i suppose.

this is all new to me, and at some point, a trained pro will need to make a visit.

walt


----------



## Hughman




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18088246
> 
> 
> I would also consider the Audyssey SubEQ. The designers of the SVS EQ were of course Audyssey. Trust me when I tell you that Audyssey saved the best elements for their product. The prices between the two are very comparable.



HI,


Is your recommendation of the SubEQ a general one or is there something in my graphs which, in your experience, highlights a specific area I would benefit (apart from the sub 30hz decay times)? The graphs depict the output from my front left speaker which has it's low fequency augmented by the Submerive for which I'm utilizing an outboard Mirage LFX-1 for low pass duties but, presently, I do not use any eq on the sub. Ideally I require a unit which will accept and apply a low pass slope from full range left and right input signals. I'd also prefer to send LFE to the same sub therefore at the end of the day three inputs would be required one with an indepedant crossover frequency and all three inputs preferably balanced.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *yacht422* /forum/post/18089724
> 
> 
> no, not really. it is a question of the intellectual type - i covered my treatments with gom, but, the superchunks covered in screen might have added to room reflections, (screen vs:gom) . i was hoping for additional insights, but, this is somewhat arcane, i suppose.
> 
> this is all new to me, and at some point, a trained pro will need to make a visit.
> 
> walt



If you already feel that maybe a "pro" will in your future, why not just do it now and get it over with? Kind of like ripping the band-aid off quick. It won't hurt as much if you do it now and quickly rather than wait and do it slowly.







Heck, you may even decide it was well worth it. If the person you decide to choose is worth their salt, you'll learn more about acoustics in a day than a year sifting through this forum. The problem with this or any other forum is that you have to know the exact question you're seeking to ask, which often leads to another question, etc. Then, you have to sift through a somewhat disorganized jungle in order to perhaps put together an answer for your question. Provided of course that the conclusion or snipets of information are correct to begin with.


----------



## SierraMikeBravo

Hughman,


Audyssey won't really allow you to customize LPF. It's entire purpose is to adjust everything automatically...relatively speaking. There is a rudimentary customizable filter interface in the software, but I never use it. Not high enough resolution nor enough range for me. In addition, if you want balanced inputs, you'll want to go with the balanced SoundEQ rather than the SubEQ. If you want a parametric EQ that can be customized to your heart's content, I would suggest looking into the QSC DSP's.


Regarding your RT60, I would focus on trying to get an actual time decay overall and not frequency based. I only use frequency based decays for large venues where certain frequencies are more important than others such as the speech range...it just depends on the application. For small rooms, it can be argued that RT60 really has no bearing. I do believe you had a waterfall plot, too. I don't remember what was there, but equalization will assist in ringing as will seating and sub placement. They are all factors. Best wishes!


----------



## Dennis Erskine

Technically speaking, there is no RT in a small room.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18092506
> 
> 
> Technically speaking, there is no RT in a small room.



Practically speaking, there is.










And even technically, RT exists in small rooms just as for large -- it just starts at a high frequency. Where a large concert hall may have a smooth, reverberant sound field starting at maybe 20-30 Hz, a small room's may start at 200-300 Hz. Everything scales linearly. And modern multiplex cinema theaters are small enough not to fit neatly into the large or small room category.


- Terry


----------



## pepar

Dueling Acousticians?


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/18093239
> 
> 
> Dueling Acousticians?



Happens all the time in the real world.


----------



## rhcorolla

Den frequency response plot curve utilizing radio shack SPL meter & tripod center listening area after sound treatment panels & corner superchunk.

Attachment 166325 


Sorry for the attachment, as not sure how to make the image show up in post.


Anyways, a look at the results & any comments are most welcome.


Room Set-up-


17' w x 11' d x 8' h

Front main towers full range

Sub xover @ 80 Hz

Early reflection panels: l/ r sides, back, l/ r front & 24" x 64" superchunk left rear corner

Floors wood w/ large rugs (basement underneath)

Walls wood paneling

Ceiling sheet rock w/ R30 insulated attic

*vvvvv Thanks pepar, much appreciated ! vvvvv*


----------



## pepar

Copy this image to your desktop and use the "attachments" button (looks like a paper clip).


----------



## SierraMikeBravo

As much as 20dB between peaks and dips....hmmmm. I don't think the super chunks are a workin'.







Have you calculated the modes for your room and is your sub in the corner? You may want to experiment with placement a little. Best wishes!


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18094139
> 
> 
> As much as 20dB between peaks and dips....hmmmm. I don't think the super chunks are a workin'.
> 
> 
> 
> 
> 
> 
> 
> Have you calculated the modes for your room and is your sub in the corner? You may want to experiment with placement a little. Best wishes!



Haven't seen the "before" ....


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/18093239
> 
> 
> Dueling Acousticians?



Not at all - they're both right.










If the second and subsequent reflections are 60+ dB down, then it's a reflection rather than reverb because it dissipated too quickly to register as reverb which is RT60 by definition. But an empty bedroom size space can have real reverb.


What did I win?










--Ethan


----------



## Hughman




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18095948
> 
> 
> Not at all - they're both right.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If the second and subsequent reflections are 60+ dB down, then it's a reflection rather than reverb because it dissipated too quickly to register as reverb which is RT60 by definition. But an empty bedroom size space can have real reverb.
> 
> 
> What did I win?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan




Apparently everyone wins, my room acoustics have improved measureably just by knowing this.


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18096154
> 
> 
> Doublemint gum?



I was thinking something for diplomacy.


----------



## glaufman

On your waterfall, switch the freq axis to LOG mode.


----------



## Gertjan

(I posted this in its own thread a little while ago, but it was suggested i posted here to get a response.)


I read about the "super chunks" in which you cut a bunch of triangles out of the rigid boards and stack 'm floor to ceiling in a corner. All the DIY "super chunk" corner traps seem to do the triangle shape in the corner. If you have the room to do a full square instead of a triangle, is that a better way to go or is it not? Are there reasons for having the diagonal face instead of a square corner? I have the space to do the full squares in the front corners of my room. I'm thinking 12x12 squares for example, instead of 12x12x17 triangles.


I have several other questions, but they are related specifically to my situation. To avoid clogging up this master thread with a discussion specific to my situation, i'm starting a separate thread for that. If you would, please visit it ( linky ) and let me know your thoughts. Thanks!


----------



## Dennis Erskine




> Quote:
> What did I win?



Nothing ... you missed the homogeneous part.


----------



## Terry Montlick




> Quote:
> Originally Posted by *dennis erskine* /forum/post/18099176
> 
> 
> nothing ... You missed the homogeneous part.



+1


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/18097959
> 
> 
> On your waterfall, switch the freq axis to LOG mode.



Based on a reply a day or two ago to a graph, I'm guessing that these are not showing an acoustically healthy room? My room sounds to dead to my ears...


----------



## graley33

Hey guys,


What about a rear wall where the rear wall is 18 feet behind the listener and 35 feet from the front wall/screen?


----------



## Weasel9992




> Quote:
> Originally Posted by *graley33* /forum/post/18099776
> 
> 
> Hey guys,
> 
> 
> What about a rear wall where the rear wall is 18 feet behind the listener and 35 feet from the front wall/screen?



That's not such a big deal from a modal or from a near-reflection standpoint, but decay times are going to be very long in a room that large. You trade one for the other.


Frank


----------



## graley33

Thanks,


It is a huge room. I know on this thread it may not be considered large but in all other respects it is quite large being that it is 40' wide by 36' long. However it is "T" shaped in that after 14' from the screen the width goes from 40' to 20' wide. The 138" screen and front speakers are mounted at the center of the T. The front row is what you might call "out in the open" in that the back of that row is 14', the second row is located 17-18' which is well inside the narrow portion of the T.


I have an 8' x 12' starceiling printed on 1" 703 (glued to MDF) on the ceiling. The rest is up for suggestions?


----------



## rxtrom

Im sure this has been mentioned before, but... APs are such a little known beneficial part of any HT but moderatly confusing. Should the topic not have its own sub-forum?


I have a bunch of questions and some of the info in this thread is extremely dated.


Does anyone visit an A/V forum that has more info on APs?


Thanks,

Rob


----------



## Ethan Winer




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18099176
> 
> 
> Nothing ... you missed the homogeneous part.



Actually, I mostly agree with you on this Dennis. To me, in order to be true reverb the added sound must swell over some amount of time, not just come quickly and decay.


--Ethan


----------



## pepar

What formula should I use to calc a target decay time for my room??


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18102851
> 
> 
> What formula should I use to calc a target decay time for my room??



I'm unsure of the specific forumula but a mixture of formaldehyde, ethanol, and methanol helps with decay time considerably. Very helpful I know.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/18102851
> 
> 
> What formula should I use to calc a target decay time for my room??



I don't think there really is one. First, it's frequency specific, so we have to start with that. There's so much debate on this in terms of what is "appropriate" and what isn't. It seems highly subjective to me.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18103501
> 
> 
> I'm unsure of the specific forumula but a mixture of formaldehyde, ethanol, and methanol helps with decay time considerably. Very helpful I know.



Can tequila be substituted for the ethanol?


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18103904
> 
> 
> Can tequila be substituted for the ethanol?



Tokillya, Ohh yeah, bad reflections though, what about that slap echo..OUCH! Nice to see this thread is alive and well.


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18103619
> 
> 
> I don't think there really is one. First, it's frequency specific, so we have to start with that. There's so much debate on this in terms of what is "appropriate" and what isn't. It seems highly subjective to me.



Could you point me to a resource that would help me understand the issue?


Jeff


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18104035
> 
> 
> Could you point me to a resource that would help me understand the issue?
> 
> 
> Jeff



I don't wish to impose but I read this last night and thought it was interesting. Perhaps the author is considered a quack within the acoustician society and the writings no more than BS but it's an interesting read anyway.

http://rds.yahoo.com/_ylt=A0geut5GAX...pter%25204.pdf


----------



## kevinzoe




> Quote:
> Originally Posted by *Hughman* /forum/post/18104143
> 
> 
> I don't wish to impose but I read this last night and thought it was interesting. Perhaps the author is considered a quack within the acoustician society and the writings no more than BS but it's an interesting read anyway.
> 
> http://rds.yahoo.com/_ylt=A0geut5GAX...pter%25204.pdf



I see you've paid the good doctor's website a visit. That's Dr. Earl Geddes who's Ph.D. was in small room acoustics and who is now selling his own line of speakers and doing consulting also.


I believe he's reputable although some of his ideas appear to contradict Dr. Floyd Toole's and Todd Welti's. For example, Geddes is a strong believer that 3 subs of different makes/brands and kinds (yes, mixing sealed with ported) randomly placed within the room will give just as good or better small room bass than Todd Welti's research and modeling using up to 5,000 subs within a room. Geddes stipulates that one sub must be in a corner while another must be elevated, so strickly speaking it's not random placement . . .


What aspects of his Chapter 4 from his book do you think are BS? Most of what he writes is pretty mainstream and accepted wisdom. . .


----------



## scsmitty

I have a question for you guys. My room is on 11' x 15' x 8'. I only have 3 wall - wall corners that I can do ssc traps. The front wall I can only manage 17" x 12" x 12" traps in each corner but in the 1 corner I have in the back I can do a 24" x 17" x 17". Would that be ok or should they all be the same size?


----------



## kevinzoe




> Quote:
> Originally Posted by *pepar* /forum/post/18102851
> 
> 
> What formula should I use to calc a target decay time for my room??



Pepar - here's the calculation for rever beration time: RT = 0.049V/A

V = the total volume in cubic feet

A = the total absorption in the room in Sabins, calculated by adding all of the boundary areas multiplied by their respective absorption coefficients. (e.g. square footage of drapes * its absorption coefficient + square footage of carpeting * its absorption coefficient etc etc)


Typical target RT's appear to range from .2 -> .4 +- and is pretty much an individual taste/preference.


----------



## Hughman




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18104466
> 
> 
> I see you've paid the good doctor's website a visit. That's Dr. Earl Geddes who's Ph.D. was in small room acoustics and who is now selling his own line of speakers and doing consulting also.
> 
> 
> I believe he's reputable although some of his ideas appear to contradict Dr. Floyd Toole's and Todd Welti's. For example, Geddes is a strong believer that 3 subs of different makes/brands and kinds (yes, mixing sealed with ported) randomly placed within the room will give just as good or better small room bass than Todd Welti's research and modeling using up to 5,000 subs within a room. Geddes stipulates that one sub must be in a corner while another must be elevated, so strickly speaking it's not random placement . . .
> 
> 
> What aspects of his Chapter 4 from his book do you think are BS? Most of what he writes is pretty mainstream and accepted wisdom. . .



I'm a layman but there was nothing in his writing I considered BS at all, I really enjoyed the article. His wall flex absorption thing might not be a practical solution but I generally agree that there's order and a musicality in chaos. I thought his writings were sensible and easy to understand but I like to leave an open for those who wish to make a counter argument, and there always is. I had no idea who the author was but my own personal listening experience gives some personal merit to his sub location theory.


----------



## kevinzoe




> Quote:
> Originally Posted by *Hughman* /forum/post/18088266
> 
> 
> No I haven't plotted RT20 or RT30 I just used the RT60 tab in REW, is this a new development on the leading edge of typical HT sized room acoustics? A quick search for RT20 on this entire site shows your post is the very first mention of it.



RT60 hogs all the limelight so it's no surprise you haven't heard of RT20 or RT30 for small rooms. It's a concept borrowed from large concert halls and scaled down for domestic sized rooms. Many knowledgable people believe that RT is unimportant or irrelevant including D'Antonio and Eger (1986), Geddes (2002), Jones (2003), Kuttroff (1998). Part of the reason being is that the numbers measured are so small compared to concert halls and the noise levels are usually higher in the home which limits how far the volume can fall before the noise floor limits it falling further . . . make sense?


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18104537
> 
> 
> Pepar - here's the calculation for rever beration time: RT = 0.049V/A
> 
> V = the total volume in cubic feet
> 
> A = the total absorption in the room in Sabins, calculated by adding all of the boundary areas multiplied by their respective absorption coefficients. (e.g. square footage of drapes * its absorption coefficient + square footage of carpeting * its absorption coefficient etc etc)
> 
> 
> Typical target RT's appear to range from .2 -> .4 +- and is pretty much an individual taste/preference.



Maybe I should be looking for a target curve; decay time vs frequency? I think I've already decided that the low 200ms range is too dead ... for me.


----------



## Hughman




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18104616
> 
> 
> RT60 hogs all the limelight so it's no surprise you haven't heard of RT20 or RT30 for small rooms. It's a concept borrowed from large concert halls and scaled down for domestic sized rooms. Many knowledgable people believe that RT is unimportant or irrelevant including D'Antonio and Eger (1986), Geddes (2002), Jones (2003), Kuttroff (1998). Part of the reason being is that the numbers measured are so small compared to concert halls and the noise levels are usually higher in the home which limits how far the volume can fall before the noise floor limits it falling further . . . make sense?



If RT60 times are typcially used for concert halls and othe large venue llive type events then there's going to be a disparity between production values and reproduction values, reproduction for intent and purpose of this thread being in the home. Similar to voicing your speakers to always sound like a piano if you voice the RT of your room to mimic the live event large room RT60, even adjusted for room size, then wouldn't targetting that same RT target for reproduction purposes essentially color the sound??


I'm not too sure I'm convinced noise levels in the home are louder than concert halls, generally when I'm in a concert hall scenerio the breathing, talking, coughing, yapping, bickering etc. generated from a hundred or hundreds of the annoying idiot event goers creates a noiseating floor far higher than what I can achieve at home, where there's generally just one or two offenders.


----------



## kevinzoe




> Quote:
> Originally Posted by *Hughman* /forum/post/18104747
> 
> 
> If RT60 times are typcially used for concert halls and othe large venue llive type events then there's going to be a disparity between production values and reproduction values, reproduction for intent and purpose of this thread being in the home. Similar to voicing your speakers to always sound like a piano if you voice the RT of your room to mimic the live event large room RT60, even adjusted for room size, then wouldn't targetting that same RT target for reproduction purposes essentially color the sound??
> 
> 
> I'm not too sure I'm convinced noise levels in the home are louder than concert halls, generally when I'm in a concert hall scenerio the breathing, talking, coughing, yapping, bickering etc. generated from a hundred or hundreds of the annoying idiot event goers creates a noiseating floor far higher than what I can achieve at home, where there's generally just one or two offenders.



Regarding your sentance: "if you voice the RT of your room to mimic the live event large room RT60, even adjusted for room size, then wouldn't targetting that same RT target for reproduction purposes essentially color the sound"


I highly doubt that you can make a domestic room have an RT of several seconds which often is the case in concert halls etc due to their size and construction, so if you try adding delay from your processor then of course you're going to colour the sound. (By the way, are you really a CDN as you spelled colour without the letter 'u'?!?) Did I misunderstand your question?


----------



## Hughman




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18104829
> 
> 
> Regarding your sentance: "if you voice the RT of your room to mimic the live event large room RT60, even adjusted for room size, then wouldn't targetting that same RT target for reproduction purposes essentially color the sound"
> 
> 
> I highly doubt that you can make a domestic room have an RT of several seconds which often is the case in concert halls etc due to their size and construction, so if you try adding delay from your processor then of course you're going to colour the sound. (By the way, are you really a CDN as you spelled colour without the letter 'u'?!?) Did I misunderstand your question?



Looking at it another way, record a live event in a large hall which has RT60times of X then playback the same recorded event in the same venue under the same conditions. Does the direct/reverberation/overall presentation sound similar to the original or does the original venue reverberation times now color the sound.


And you questioning whether I'm Canadian cuts me to the bone I'm, at these very moments, blowing (in my nicely heated cabbed tractor I might add) and flooding an approx 40,000 square foot hockey rink on lake in in my back yard. I hope you're not one of those Canadian posers.


----------



## kevinzoe




> Quote:
> Originally Posted by *Hughman* /forum/post/18104897
> 
> 
> Looking at it another way, record a live event in a large hall which has RT60times of X then playback the same recorded event in the same venue under the same conditions. Does the direct/reverberation/overall presentation sound similar to the original or does the original venue reverberation times now color the sound.
> 
> 
> And you questioning whether I'm Canadian cuts me to the bone I'm, at these very moments, blowing (in my nicely heated cabbed tractor I might add) and flooding an approx 40,000 square foot hockey rink on the lake in my back yard. I hope you're not one of those Canadian posers.



Sorry to have cut you to the bone - hope you're a fast healer







What do you mean by a "CDN Poser" by the way? I'm in Toronto GTA, where are you?


As for whether the original venue's reverb will colour the recorded reverb of your scenario, I would expect that it might becasue it's equal in length to the recorded amount made in the same venue. For domestic-type rooms I don't think there is an issue becasue the RT time is less than what's been recorded. As Toole writes, "it seems that the basic audible effects of early reflections in recordings are well preserved in the reflective sound fields of ordinary rooms. There is no requirement to absorb first reflections to allow recorded reflections to be heard."


----------



## Hughman




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18105012
> 
> 
> Sorry to have cut you to the bone - hope you're a fast healer
> 
> 
> 
> 
> 
> 
> 
> What do you mean by a "CDN Poser" by the way? I'm in Toronto GTA.



Yes I'm quite resilent, we'd be extinct othewise. Just what I thought.







Quelle heure est-il, colour est-il, color est-il.



> Quote:
> Originally Posted by *kevinzoe* /forum/post/18105012
> 
> 
> As for whether the original venue's reverb will colour the recorded reverb of your scenario, I would expect that it might becasue it's equal in length to the recorded amount made in the same venue. For domestic-type rooms I don't think there is an issue becasue the RT time is less than what's been recorded. As Toole writes, "it seems that the basic audible effects of early reflections in recordings are well preserved in the reflective sound fields of ordinary rooms. There is no requirement to absorb first reflections to allow recorded reflections to be heard."



This appears somewhat constistent with what Geddes is saying regarding keeping, above bass frequency, absorption in small rooms to a minimum. Does Toole provide an opinion on the preservation of later recorded reflections or reveberations. Think I'll buy Tooles book, from the few snippets I've seen on the web it looks to be quite good.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18102672
> 
> 
> Actually, I mostly agree with you on this Dennis. To me, in order to be true reverb the added sound must swell over some amount of time, not just come quickly and decay.
> 
> 
> --Ethan



Think mode density and overlap, Ethan.


- Terry


----------



## Ethan Winer




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18106590
> 
> 
> Think mode density and overlap, Ethan.



I understand, and clearly modal ringing is a type of reverb.


--Ethan


----------



## ninja12

I have B&W CCM817 located in the ceiling. Do you think installing a back box would have any acoustic improvement?


----------



## Dennis Erskine




> Quote:
> I have B&W CCM817 located in the ceiling. Do you think installing a back box would have any acoustic improvement?



It will do something...an improvement? Roll the dice. The speaker's response was based upon some (unknown to us) open cavity behind it. You make the cavity significantly smaller, you significantly change the performance and FR of the speaker. If you want a high performance speaker (and for that kind of money, I think you would), get a speaker that's already in a backbox from the manufacturer.


----------



## scsmitty

I have a question for you guys. My room is on 11' x 15' x 8'. I only have 3 wall - wall corners that I can do ssc traps. The front wall I can only manage 17" x 12" x 12" traps in each corner but in the 1 corner I have in the back I can do a 24" x 17" x 17". Would that be ok or should they all be the same size?


----------



## ninja12




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18111566
> 
> 
> It will do something...an improvement? Roll the dice. The speaker's response was based upon some (unknown to us) open cavity behind it. You make the cavity significantly smaller, you significantly change the performance and FR of the speaker. If you want a high performance speaker (and for that kind of money, I think you would), get a speaker that's already in a backbox from the manufacturer.



I was kind of thinking the same thing. I have been in the HT hobby for a while and one thing that I have learned is that you really don't know how it's going to sound until you try it. People give a lot of good advice; but, you really don't know how it's going to turn out until you try it in your room. Anyway, thanks for responding.


----------



## pepar




> Quote:
> Originally Posted by *scsmitty* /forum/post/18112831
> 
> 
> I have a question for you guys. My room is on 11' x 15' x 8'. I only have 3 wall - wall corners that I can do ssc traps. The front wall I can only manage 17" x 12" x 12" traps in each corner but in the 1 corner I have in the back I can do a 24" x 17" x 17". Would that be ok or should they all be the same size?



The more, the better and the bigger, the better. But they do not have to be the same size. Install what you can.


----------



## Weasel9992




> Quote:
> Originally Posted by *scsmitty* /forum/post/18112831
> 
> 
> I have a question for you guys. My room is on 11' x 15' x 8'. I only have 3 wall - wall corners that I can do ssc traps. The front wall I can only manage 17" x 12" x 12" traps in each corner but in the 1 corner I have in the back I can do a 24" x 17" x 17". Would that be ok or should they all be the same size?



17x12x12 is just a hair small...the arbitrary minimum width is usually 18". That said, you have to treat the room as-is unless you want to change it. The fact that they're different in the back than in the front isn't ideal, but it's not a huge deal.


Frank


----------



## johnbomb

I'm considering building a QRD (slat) diffuser for my back wall, with a design frequency of around 2000 Hz, whose wells will be bottomed by FRK faced rigid insulation. Behind the diffuser will be about 4" thick of rigid insulation on the wall.


The idea is this: frequencies below whatever the FRK reflects (1-2khz) will be absorbed by the 4" insulation (to a low cutoff, of course), and above that will be diffused. I read somewhere that diffusing frequencies above 1-2khz might be most beneficial to creating the aura of spaciousness that diffusion can provide. By keeping the design frequency this high, the minimum listener distance to the diffuser is kept as low as possible.


What do you think? Preferably, I'd like to use something other than FRK, from an aesthetic point of view, such as thin wood, like Luan or even veneer. Would that work?


Thanks,

John


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/18115316
> 
> 
> I'm considering building a QRD (slat) diffuser for my back wall, with a design frequency of around 2000 Hz, whose wells will be bottomed by FRK faced rigid insulation. Behind the diffuser will be about 4" thick of rigid insulation on the wall.
> 
> 
> The idea is this: frequencies below whatever the FRK reflects (1-2khz) will be absorbed by the 4" insulation (to a low cutoff, of course), and above that will be diffused. I read somewhere that diffusing frequencies above 1-2khz might be most beneficial to creating the aura of spaciousness that diffusion can provide. By keeping the design frequency this high, the minimum listener distance to the diffuser is kept as low as possible.
> 
> 
> What do you think? Preferably, I'd like to use something other than FRK, from an aesthetic point of view, such as thin wood, like Luan or even veneer. Would that work?
> 
> 
> 
> 
> Thanks,
> 
> John



John - Lets back up a tad . . . It sounds like your main constrain is to "minimize the listener distance to the diffuser" . . . have I got that right? How far is the back wall from the listeners?


DIFFUSER TYPE OPTIONS: If this is the main constraint, then you may be better to build a Skyline diffuser rather than the QRD; as the QRD only diffuses horizontally, the Skyline diffuses horizontally AND vertically so with less horizontal energy coming at you, you can affort to sit closer to the Skyline than the QRD. Another option is to place absorption in the middle of the back wall and diffusion on either side of it, which may increase the distance between it and the listener(s) . . . Still another option is a hemi-cylindrical diffuser but like the QRD it only diffuses in one dimension - horizontally when oriented vertically. The hemi diffuser allows you to stuff the concave interior with fibreglass and the low freq absorption is a funtion of the radius depth (greater radius=lower freq absorption); just put some wooden veneer/laminate that comes with a pre-glued backing on the front convex part so as not to absorb the mid/high frequencies. (I just finished building two of these hemi-cylindrical diffusers and have also build several Sklyines, so PM me if you want pictures etc.)


DIFFUSER HIGH/LOW DESIGN FREQUENCIES: How high a frequency do you think your QRD will diffuse to?







Most QRDs won't diffuse higher than 3KHz-4KHz which would give you a whopping 1 octave of diffusion from your planned 2KHz "design frequency" - hardly worth it in my mind. With Skylines, it's the block size (not length) that determines the upper freq range -- even with a 1" * 1" block size for a Skyline as used in George Massenburg's famous Studio C, it'll only work as high as about 6.75KHz. The highest note on a piano is about 4,186Hz to give this upper freq design some context.


For the low freq design, I'd suggest it go down to the Schroeder/transition frequency which for domestic rooms seems to be between 300-500Hz, which is only a range of about 9-10 semi-tones (not even an octave). The QRD well depth and Skyline cell depth determines the low freq diffusion effectiveness. I would think your 4" of absorption behind the diffuser (whichever kind you choose) is a good idea or put it below or above it in the floor or ceiling corners. You could build a 'box' to sit your diffuser on and fill the box with fibreglass to act as the bass trap so you'd be absorbing low freq's and diffusing mid/high freq's thereby maintaining the spaciousness you seek.


I would guess that you're thinking is that rigid insulation at the back of the QRD wells will 'reflect' mid/high frequencies which may work for the highs but less likely to work for the mid's so use instead Luan wood or wood laminate that is hard enough not to absorb them.


Hope this helps . . .


----------



## graley33

There is a how-to online from one of the frequent posters here about using plywood and making a resonator. Due to the complexities of a resonator, if I wanted to just make a trap in the corner but wanted it to look like a column, could it be covered with thin 3/8" MDF or will that reflect too much to make it work as a trap? I can use fabric and cover it but I'd rather paint it if possible.


----------



## Ethan Winer

MDF in front of a fiberglass-only absorber will prevent the absorber from working. So the answer is no, don't do that!










However, brown "box" cardboard works fine if it's not really thick, because bass passes through it easily.


--Ethan


----------



## Elill

I beleive that builders plastic also works - but you'd want to cover that with a fabric frame.


----------



## kevinzoe




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18124693
> 
> 
> MDF in front of a fiberglass-only absorber will prevent the absorber from working. So the answer is no, don't do that!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> However, brown "box" cardboard works fine if it's not really thick, because bass passes through it easily.
> 
> 
> --Ethan



Ethan - clarification question if I may - at what general frequency range will the MDF prevent the fibreglass behind it from working as an absorber? Obviously, MDF will reflect high frequencies (with short wavelengths) but where is the line in terms of MDF thickness or low frequency for the a 3/8 or 1/2 inch MDF when bass will still pass through it into the fibreglass behind it?


----------



## graley33

Thanks Ethan,


I see photos of people doing it a lot but I suppose either they just think it will work (and are wrong) or they are making a resonator of some sort which is beyond my skill set at this time. However, I did order Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms today so after 500+ pages of that and sleeping at a Holiday Inn Express I may be closer.


----------



## Gertjan

So uhm... given this graph, where should i start??


----------



## Elill

I'm no expert, but from what I understand that looks aweful, something royal.


What are the dimensions of your room?


I assume zero treatments?


----------



## ufokillerz

built 2 of these for my open living room so far! hope they work well. and baaahhhh to my floor, it is not level at certain places.


first time building these, oc703, 2x2" per frame. birch plywood - homedepot crap grade, birch that looked perfectly flat, but wasn't. ripped to size on a table saw and miter saw i have never used before.

burlap adhered to the sides of the oc703 with scotch 90 spray adhesive. No adhesive on the faces that are not covered with wood. friction fit in the frame. approximately $50 in materials for the both, maybe even less.


----------



## Dennis Erskine




> Quote:
> So uhm... given this graph, where should i start??



Over.










I'd start with a focus on your low frequency issues and then work up the food chain from there. Have you posted pics of this space?


----------



## pepar




> Quote:
> Originally Posted by *Gertjan* /forum/post/18126566
> 
> 
> So uhm... given this graph, where should i start??



Thanks for posting. I don't feel so bad now.










I would start with bass traps ... in the corners. If you are a DIY'er, check here .


----------



## pepar




> Quote:
> Originally Posted by *ufokillerz* /forum/post/18127279
> 
> 
> built 2 of these for my open living room so far! hope they work well. and baaahhhh to my floor, it is not level at certain places.



Nice clamps.


----------



## ufokillerz




> Quote:
> Originally Posted by *pepar* /forum/post/18127779
> 
> 
> Nice clamps.



yea thats to fix a crack in the plywood, applied gorilla wood glue, and clamp for a day till dry, these babies are fresh from my factory in the other half of the living room.


----------



## Weasel9992




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18127581
> 
> 
> Over.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'd start with a focus on your low frequency issues and then work up the food chain from there. Have you posted pics of this space?



I agree. Something doesn't look right though. How big is this space?


Frank


----------



## Gertjan




> Quote:
> Originally Posted by *Elill* /forum/post/18126959
> 
> 
> I'm no expert, but from what I understand that looks aweful, something royal.



That's kinda what i was thinking too yeah











> Quote:
> What are the dimensions of your room?



16'7" x 13'9", ceiling (drop tile) is about 91" in the back 2/3rds, then 94" in the front 1/3rd.



> Quote:
> I assume zero treatments?



Correct. That's why i came to this thread to see if treatments would help cure some of these problems


----------



## Gertjan




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18127581
> 
> 
> Over.



Where's the LOL smiley when you need it







In my old house in Marietta (your neck of the woods, i really need to stop by sometime!) i had a 14'x30' dedicated room, which sounded pretty decent to me. Moved to this new place in Canton in Nov '08, and the basement was the only place i could practically set up a small "HT". The sound here has been less satisfying than at the old place (as should be obvious from the graph!). Been too busy with other things this past year (moved to a horse farm, so there's always something to do), but now i'm finally making some time to sit down and tackle this room to see what i can do with it.



> Quote:
> I'd start with a focus on your low frequency issues and then work up the food chain from there.



I had EQ'd my sub before to try to get a decent bass response in the main seat. I got it fairly flat with a nice roll-off. But i know that EQ should typically be the last thing to do. So reading here about bass traps got me thinking i should probably look into those











> Quote:
> Have you posted pics of this space?



In another thread in the Audio Setup forum, but i'll repost them here if that's alright:











This room is in the basement, which is underground. It's a poured concrete foundation. Drywall all around. Front wall of the HT room has the concrete behind it. All other walls are studs + drywall.


The sub (15", 2'x2'x4') i built myself for the HT room in our previous home, which was 14'x30'. This new room is only 13'9"x16'7", so the sub is a big massive in here now. It seems i have this nasty null at 40Hz. I assume that's partially due to the placement of the sub in the center on the front wall.


The mains are sitting on top of the sub, and the TV (42" LCD) on top of the main center. I'm hoping to get back to a front projection setup in the next year or 2 (waiting for 3D projectors to become more mainstream) and have a ~6' wide acoustically transparent screen.


I can see putting some good size traps (super chunk style) in the front corners. The rear is the PITA. It has three doors (closet, bathroom, garage) which means i can't do anything significant on that wall. In the rear left corner i have barely any room due to the door to the garage swinging in. In the rear right corner i have that funky corner poking out. I've been playing with designs for a super chunk style bass trap there, and came up with this:











That's a LOT of material though! I don't have a big budget allocated for this; a couple hundred bucks is all i can spare at the moment on this. I'm fine with DIY-ing it, just trying to figure out where to start.


----------



## Gertjan




> Quote:
> Originally Posted by *pepar* /forum/post/18127762
> 
> 
> Thanks for posting. I don't feel so bad now.



You're welcome











> Quote:
> I would start with bass traps ... in the corners. If you are a DIY'er, check here .



Thanks, i'll read up some more there as well. Already been reading a ton about bass traps and other acoustic treatments using rigid fiberglass panels, and i'm hoping to be able to do some of that. Just trying to figure out specifics for my situation now.


----------



## Gertjan




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18127823
> 
> 
> I agree. Something doesn't look right though. How big is this space?



Pretty small - 13'9" x 16'7". It could certainly be that i'm doing something wrong with the measurements. I used REW (4.11), my laptop, and a Radioshack SPL meter. Hooked up to my AVR, and did all the calibration in REW (soundcard, mic/meter etc), and then measured. Is there anything in particular that looks off to you in that graph, or just the whole thing? Did i perhaps do something wrong generating the waterfall? I just clicked the "generate" button after the measurement...


----------



## Ethan Winer




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18125207
> 
> 
> at what general frequency range will the MDF prevent the fibreglass behind it from working as an absorber?



It depends entirely on the thickness. I do not have hard data, but I imagine it's out there if you Google it. Or maybe someone here can post a link. I can tell you that 3/8 inch thick MDF is much too thick, but 1/32th inch thick wood veneer is probably thin enough to pass most bass frequencies okay.


--Ethan


----------



## pepar

I do not have any measurements from "before" I installed my acoustical treatrments, but here are the measurements with no electronic correction and then with both the SVS AS-EQ1 and Audyssey MultEQ Pro applied. I will soon be adding more traps to try to clean it up under 100Hz and will post more measurements then.


----------



## Elill

pepar - thats really rather impressive.....I can see another sub and MultEQ in my future


You sure you dont want to rip out your treatments for the fun of it so we can see?










What program/gear do you do your measurements with?


----------



## pepar




> Quote:
> Originally Posted by *Elill* /forum/post/18129708
> 
> 
> pepar - thats really rather impressive.....I can see another sub and MultEQ in my future
> 
> 
> You sure you dont want to rip out your treatments for the fun of it so we can see?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> What program/gear do you do your measurements with?



Umm, no, I'm not that curious. Plus I *remember* how (bad) it sounded before the traps.


Room EQ Wizard, an M-Audio MobilePre sound "card", Audyssey Pro mic w/3rd party cal file and a 32-bit Win 7 HP laptop.


Once you've had two, you can never go back to one ... sub.







Actually, I have four subs - collocated pairs.


----------



## Hughman

Pepar,


Are you using frictional absorption for the bass or something else, and how much? Those decay times look quite low, is there anything about the sound quality which you might refer to as stuffy or dry?


General question for anyone, can floor resonances of the overhead floor cause significant 10-30hz ringing (I've been thinking for a long time this might be my issue ) and if so can absorption be a practical solution other than redesigning the floor?


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18129953
> 
> 
> Pepar,
> 
> 
> Are you using frictional absorption for the bass or something else, and how much?



Twenty-nine lineal feet of 17x17x24 superchunked OC703. Check my website linked in my sig.



> Quote:
> Those decay times look quite low, is there anything about the sound quality which you might refer to as stuffy or dry?



Yes, a bit. And that's why I am going to remove some of the 2" Linacoustic on my front wall, reduce the size of the front left and right first reflection point absorbers (2" OC SelectSound Black), mount diffusors above and below the newly sized absorbers and install some diffusors in the rear of the room. Not sure I'll net much because I am installing about another twenty-four lineal feet of superchunk in the rear. I really want to knock down the ringing below 80Hz.


----------



## Gertjan

So i figured i'd run a waterfall of the soundcard... This is what i got:











I do not know what i was expecting, but this doesn't look right to me. What do you think? What's it supposed to look like? Since it's the loopback, shouldn't it basically drop off right away instead of decaying that slowly?


EDIT:


Well, i ran the same test on a desktop computer, and its soundcard gives me this waterfall:











I guess that's normal for soundcards then? Still puzzles me a bit; I would expect the decay to be immediate...?


----------



## pepar

I don't think that "stuff" below 50Hz on the purple graph should be there. Is that a laptop's integrated sound?


Here is a waterfall of REW's measurement of my USB sound "card" from the process of generating a CAL file. It is more of a professional device, so the nearly ruler flat response doesn't surprise me. What does surprise me is how _very_ non-linear the two are that you measured. Perhaps a waterfall of a looped back sound card is not a valid measurement; mine has a similar falloff like yours, but then has some sort of ongoing broadband noise that ... goes off a cliff like a gate closed just short of 250ms.


----------



## Gertjan




> Quote:
> Originally Posted by *pepar* /forum/post/18132930
> 
> 
> I don't think that "stuff" below 50Hz on the purple graph should be there. Is that a laptop's integrated sound?



Yup, it's the laptop's integrated sound. I guess i should not be surprised that it has those problems in the low end.



> Quote:
> Here is a waterfall of REW's measurement of my USB sound "card" from the process of generating a CAL file. It is more of a professional device, so the nearly ruler flat response doesn't surprise me. What does surprise me is how _very_ non-linear the two are that you measured. Perhaps a waterfall of a looped back sound card is not a valid measurement; mine has a similar falloff like yours, but then has some sort of ongoing broadband noise that ... goes off a cliff like a gate closed just short of 250ms.



Interesting, thanks for posting that. Looks like it might be normal for the soundcard waterfall to have that "horizontal cylinder" look then. And i'm wondering as well if the loopback test is not a valid measurement to graph a waterfall.


The red graph i posted is for the on-board audio of a cheap desktop i had sitting around. It's a Microcenter special, the sound chip is a RealTek. I'm not terribly surprised that it's not ruler flat. The "saddle" type curve seems to be inverse to the FR graph, interestingly enough. I do not know if REW is using the calibration of the soundcard in that waterfall to overcompensate perhaps.


My normal desktop has an Audigy card, and that card's FR is ruler flat as well. The problem was when i hooked it up to my AVR to test, i got a mid-frequency "hum", which i was unable to eliminate, so i couldn't use it to do further measurements


----------



## pepar




> Quote:
> Originally Posted by *Gertjan* /forum/post/18133097
> 
> 
> My normal desktop has an Audigy card, and that card's FR is ruler flat as well. The problem was when i hooked it up to my AVR to test, i got a mid-frequency "hum", which i was unable to eliminate, so i couldn't use it to do further measurements



A laptop on battery power is the way to go. But the integrated sound on laptops is usually not duplex, i.e. cannot output on one channel while inputting (the test mic's signal) on the other channel. So nearly everybody uses a USB device.


----------



## Hughman

Thanks for the info Pepar. Just for kicks I turned off the audio to produce a waterfall of the room/house itself. First graph is room with fridge running upstairs, next is with fridge turned off. As you can see the fridge being situation on the same floor span as the HT ceiling creates quite a spike at 20hz and it's harmonic at 40hz, both would appear to be excitation of floor resonanes at sub-harmonics of the fridge motor. I have no idea what's causing the 34 and 43hz spikes.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Hughman* /forum/post/18133434
> 
> 
> Thanks for the info Pepar. Just for kicks I turned off the audio to produce a waterfall of the room/house itself. First graph is room with fridge running upstairs, next is with fridge turned off. As you can see the fridge being situation on the same floor span as the HT ceiling creates quite a spike at 20hz and it's harmonic at 40hz. I have no idea what's causing the 34 and 43hz spikes.



In professional movie location sound recording, one of the first things they teach is "unplug the refrigerator."










- Terry


----------



## Hughman




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18133534
> 
> 
> In professional movie location sound recording, one of the first things they teach is "unplug the refrigerator."
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> - Terry



That would be lesson #2, lesson #1 is alternative methods of keeping beer chilled.


----------



## pepar




> Quote:
> Originally Posted by *Hughman* /forum/post/18133735
> 
> 
> That would be lesson #2, lesson #1 is alternative methods of keeping beer chilled.



Craft services.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Hughman* /forum/post/18133735
> 
> 
> That would be lesson #2, lesson #1 is alternative methods of keeping beer chilled.



Actually, alcohol on the set is generally a no-no. Otherwise you may never finish shooting the movie! Gotta hold out until the wrap party.


----------



## Hughman




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18133827
> 
> 
> Actually, alcohol on the set is generally a no-no. Otherwise you may never finish shooting the movie! Gotta hold out until the wrap party.



And the shaky-cam was born.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Hughman* /forum/post/18133929
> 
> 
> And the shaky-cam was born.



Actually, the real "shaky cam" was developed by director Sam Raimi.


Enough with the OT already! I'm the worst offender!!


----------



## kevinzoe




> Quote:
> Originally Posted by *Hughman* /forum/post/18133434
> 
> 
> Thanks for the info Pepar. Just for kicks I turned off the audio to produce a waterfall of the room/house itself. First graph is room with fridge running upstairs, next is with fridge turned off. As you can see the fridge being situation on the same floor span as the HT ceiling creates quite a spike at 20hz and it's harmonic at 40hz, both would appear to be excitation of floor resonanes at sub-harmonics of the fridge motor. I have no idea what's causing the 34 and 43hz spikes.



Nice graphs and interesting audio insight from that darn fridge . .

Remember I mentioned a little while back about the "noise" level of the house in relation to RT20/30/60 discussion? You've got at least 65-70dB background noise! Would the other noise be from say the furnace?


----------



## Hughman




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18134105
> 
> 
> Nice graphs and interesting audio insight from that darn fridge . .
> 
> Remember I mentioned a little while back about the "noise" level of the house in relation to RT20/30/60 discussion? You've got at least 65-70dB background noise! Would the other noise be from say the furnace?



Hopefully the fridge noise is temporary, It's been moved while some reno's are being done in the kitchen, if not some isolation devices maybe in order (the wife's going to love that one). I have no other mechanical systems operating in the home except another fridge in a room next to the theater which completely slipped my mind and I suspect is the culprit of the 34/43hz noise.

I've suspected for a long time floor resonances from the span may have been causing problems with decay times down low and evidenced by the excitation of the 20hz peak induced by the fridge I think I may have been correct. I originally designed the ceiling/floor to flex and dissipate energy at 20hz, I wonder went wrong







.


----------



## Hughman

Further to my recent room waterfall, here's the latest with both refrigerators off. Also, with the room at the most quiet I can make it (except for desktop running adjacent to HT to run program) here's a comparison frequency response of the room with and without the projector running.


For the theater designers, what ambient noise levels do you target for a theater with the projector running.


----------



## pepar

Hughman - About all you can do is build a hushbox or buy a quieter projector.


Is that LF rumbling from the projector??


----------



## glaufman




> Quote:
> Originally Posted by *Gertjan* /forum/post/18130703
> 
> 
> So i figured i'd run a waterfall of the soundcard... This is what i got:?



Before we bother talking about decay times, we've got to get the FR looking right... it looks like you've got the "C-Weighted Mic" radio button in the MIC tab of the settings window, which should be unchecked for running a loopback measurement, or for that matter any measurement where you're not using a C-Weighted mic...


----------



## Hughman




> Quote:
> Originally Posted by *pepar* /forum/post/18138470
> 
> 
> Hughman - About all you can do is build a hushbox or buy a quieter projector.
> 
> 
> Is that LF rumbling from the projector??



I think I'll have to leave it as is or by a more quiet projector. I have a shelf system which enables me to raise or lower the PJ to adjust for bulb aging (high power screen). I'm presently running the PJ on high lamp mode.


I surmise at this point the Sub 20hz noise is likely an artifact of the rather large lake I live on and the ice which is in a constant state of expansion/contraction.


----------



## Gertjan




> Quote:
> Originally Posted by *glaufman* /forum/post/18138586
> 
> 
> Before we bother talking about decay times, we've got to get the FR looking right... it looks like you've got the "C-Weighted Mic" radio button in the MIC tab of the settings window, which should be unchecked for running a loopback measurement



I'm 99% certain i had it unchecked for the loopback test. But thanks for that thought, i will check it again tonight or tomorrow night when i get a chance.


----------



## glaufman

A few points about reading REW graphs for everyone:

1: When posting a waterfall, make sure the frequency axis is in LOG mode. There is a known bug with the Freq axis in LIN mode that makes the plot unreliable.

2: Post an FR along with the waterfall with the same graph limits to make it easy to match up.

3: When posting your FR, before making the jpg, make sure to check the soundcard cal and mic cal buttons under the plot to display these traces on the plot. This allow people to see where in the very low or very high end your data becomes unreliable due to the effect of the cal files on your noise floor.

4: Don't sweat persistent noise very low, unless you absolutely have to and are absolutely sure your setup has a noise floor capable of these measurements.


----------



## MUTTS

Somewhat afraid to post here as I think youll have a field day with this but Id love to get your thoughts. I realize the room will never be acoustically perfect.


Ok---been lurking here for years. Now getting serious and actually close to finishing my theater. Heres the catch....its in an outbuilding/barn/playhouse behind our house. Its a neat building with a large playroom/gymnasium. The theater will be in the loft that overlooks the play area. The theater is 20 feet wide by 30 ft deep. The first 20 ft of the loft will be theater, with a bar gathering area in the back 10 ft. Jason from AVS did my prewire when I was very ignorant. Now nearly two years later and I know a lot more (but still learning) and Im doing most of the finish work myself.


Heres the dilemma: the loft is open to the gym below. Roughly 18 of the 30 ft of wall are open to below. Now I know the audiophiles are going to freak, but it is a cool thing to see. Hopefully these pics I post show up.


I dont care about limiting sound in the sense that its a separate building so I dont care about sound getting into the gym. We wont be playing hoops and watching movies simultaneously. I am very concerned when watching movies about echo bouncing back from the gym. So--Id like to be able to close off the opening during movie watching (I dont think it will matter much while watching sports as I likely wont be cranking the sound). Ive got some thoughts but would like to see what the forum thinks.


Thanks in advance....heres the pics to help explain:































Tony


----------



## mike2060




> Quote:
> Originally Posted by *pepar* /forum/post/18130187
> 
> 
> Twenty-nine lineal feet of 17x17x24 superchunked OC703. Check my website linked in my sig.
> 
> 
> 
> Yes, a bit. And that's why I am going to remove some of the 2" Linacoustic on my front wall, reduce the size of the front left and right first reflection point absorbers (2" OC SelectSound Black), mount diffusors above and below the newly sized absorbers and install some diffusors in the rear of the room. Not sure I'll net much because I am installing about another twenty-four lineal feet of superchunk in the rear. I really want to knock down the ringing below 80Hz.



I'd just remove all first reflection point absorption so your room isn't as dead assuming your waterfall is accurate.


----------



## The_Nephilim1

Hi, Looking to improve my Room Acoustics as they are probally needed.. All I have availble is a SPL Meter along with a Test Tones CD. Will I be able to test my room with that or do I need a Fancy Gizmo to do the readings??


Here is a Pic of my Room it is in the Basement with the Right and Rear wall being Cynderblocks with Drywall over... On the Front and Left Wall When I built it I put in 2" Insulation between the Studs to the Ceiling, the Styrofoam kind of Insulation..


Would Someone be able to tell me what to Add or do I need to make Measurments first??











By the_nephilim at 2010-02-16




Also here is my Webpage with some Before and after shots. Also I havea 7' Drop ceiling and did NOT put any insulation inbetween the Joists above the ceiling Should I??


http://home.comcast.net/~glafsr/wsb/...ome.html-.html


----------



## Weasel9992




> Quote:
> Originally Posted by *MUTTS* /forum/post/18148172
> 
> http://s746.photobucket.com/albums/x...t=IMG_3228.jpg



Can't open the link...well, I can but it just takes me to the photobucket home page.


Frank


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18148618
> 
> 
> I'd just remove all first reflection point absorption so your room isn't as dead assuming your waterfall is accurate.



Thanks, Mike. The FRP absorbers are needed. There are other things I can do to increase reverb time if I want to.


Jeff


----------



## MUTTS




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18152437
> 
> 
> Can't open the link...well, I can but it just takes me to the photobucket home page.
> 
> 
> Frank



Fixed....pics now in post. Blame the new guy!


Tony


----------



## mike2060




> Quote:
> Originally Posted by *pepar* /forum/post/18152531
> 
> 
> Thanks, Mike. The FRP absorbers are needed. There are other things I can do to increase reverb time if I want to.
> 
> 
> Jeff



You don't need the FRP treatment. They don't do anything beneficial, probably more harm than good being only 2" thick. They basically take your speaker's off-axis response and strip away the higher frequencies and send you back stuff between 200-500hz. I find treating the FRPs hurt dialogue in my experience. I would at least suggest taking the side and ceiling treatment down and seeing how it sounds. You can always put it back up.


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18152857
> 
> 
> You don't need the FRPs. They don't do anything, probably more harm than good being only 2" thick.



I had the benefit of using my theater without the absorbers for a while and then adding them one or, in the case of the front left and right, two at a time. I can _assure you_ that they are doing a lot in the way of improving imaging of LCR. I understand your comment about them being only 2", but the bass traps handle what would be absorbed by increasing to 4".


----------



## mike2060




> Quote:
> Originally Posted by *pepar* /forum/post/18152896
> 
> 
> I had the benefit of using my theater without the absorbers for a while and then adding them one or, in the case of the front left and right, two at a time. I can _assure you_ that they are doing a lot in the way of improving imaging of LCR. I understand your comment about them being only 2", but the bass traps handle what would be absorbed by increasing to 4".



I'm talking about 200-500hz reflections coming from the FRPs. Bass traps in corners will not magically remove those.



There's a lot of information here if u have a little bit of time.

http://www.harman.com/EN-US/OurCompa...ions/13686.pdf


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18152990
> 
> 
> I'm talking about 200-500hz reflections coming from the FRPs. Bass traps in corners will not magically remove those.



Ahhh, I see. Well, it is possible to up them to 4" because I am considering reducing them from 48x48 to 24x48 and mounting diffusors above and below them, and the diffusors will likely be 4" or so.


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18152990
> 
> 
> http://www.harman.com/EN-US/OurCompa...ions/13686.pdf



Yeah, I've read that doc before. Dueling acousticians is what I see. Toole likes all lateral reflections, Geddes doesn't like the first(/early?) reflections, but likes the rest of them ... and they both can explain why.


Jeff


----------



## mike2060

Toole doesn't mention personal preference but what the experiments tell him. I don't know if Geddes has some preference or he actually has data to say that first reflections are bad.


Edit: I actually have found some of his papers and am reading them over. I found this quote "Toole is a strong proponent of a large amount of VER (me-very early reflections but I don't know what they are) because of its increase of the spaciousness effect. He appears to discount the negative aspects of this on imaging however. (Dr. Toole, does not make many statements about "image", perhaps being concerned over its loose definition).


I think if you are going to tame the early reflections you should make the treatment at least 4" no matter who is correct on this matter.


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18153934
> 
> 
> Toole doesn't mention personal preference but what the experiments tell him. I don't know if Geddes has some preference or he actually has data to say that first reflections are bad.



OK, OK, if you're going to parse it that precisely, I guess I characterized it as personal preference for the purposes of saying it simply. They both use their data to support their positions. Geddes' data "says" first reflection smear the image and I agree based on my own experience in my theater.


Jeff


----------



## adammb

Can anyone clarify on whether or not you need to have A/T cloth on side wall treatments. I am wanting to have a 3-4" side wall treatments and want something that looks better and possible cheaper than GOM. I am going to use GOM for the front wall and speaker cloth for my false soffits but am wondering about the fabric to wrap around the side wall treatments.


The more I read the more that people say the opposite things. My guess is to use a fabric that is somewhat of a loose weeve but looks good and does not have a high reflective amount to it.


Any and all advice would be greatly appreciated as I want to order the GOM today and need to know if I need to order for the side walls.


Also, if I dont use GOM then I have a larger selection of colors.


----------



## Tom Cecc

I am working on building a pair of diffusors to place at the front wall behind my Magnepan 1.6's. The speakers are 19" wide by 65" high and I was going to make the diffusors 2'x4'. Is this a proper size or should they be wider/taller?


Also, how much distance should be between the speakers and diffusors? Is 3' to 4' enough? From what I have read, the distance is more critical between the listener and diffusor than it it is for the speaker and diffusor. Is this correct?


Thanks


----------



## Terry Montlick




> Quote:
> Originally Posted by *adammb* /forum/post/18154149
> 
> 
> Can anyone clarify on whether or not you need to have A/T cloth on side wall treatments. I am wanting to have a 3-4" side wall treatments and want something that looks better and possible cheaper than GOM. I am going to use GOM for the front wall and speaker cloth for my false soffits but am wondering about the fabric to wrap around the side wall treatments.
> 
> 
> The more I read the more that people say the opposite things. My guess is to use a fabric that is somewhat of a loose weeve but looks good and does not have a high reflective amount to it.



You don't need to use GOM for wall treatments. If you want to make the best use of the absorptive material behind the fabric over the largest range of frequencies, make sure that you can blow through it relatively easily.


The rooms I design have calculated characteristics based on the absorption and diffusion of the materials in the room. If somebody is using a marginally acoustically transparent fabric, *I* need to know about it. But most people play it by ear, and don't hire an acoustician or do any math or modeling.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18159383
> 
> 
> You don't need to use GOM for wall treatments. If you want to make the best use of the absorptive material behind the fabric over the largest range of frequencies, make sure that you can blow through it relatively easily.
> 
> 
> The rooms I design have calculated characteristics based on the absorption and diffusion of the materials in the room. If somebody is using a marginally acoustically transparent fabric, *I* need to know about it. But *most people play it by ear*, and don't hire an acoustician or do any math or modeling.



groan


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/18159522
> 
> 
> groan



Hahaha....










Frank


----------



## Tom Cecc




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18159383
> 
> 
> You don't need to use GOM for wall treatments. If you want to make the best use of the absorptive material behind the fabric over the largest range of frequencies, make sure that you can blow through it relatively easily.
> 
> 
> The rooms I design have calculated characteristics based on the absorption and diffusion of the materials in the room. If somebody is using a marginally acoustically transparent fabric, *I* need to know about it. But most people play it by ear, and don't hire an acoustician or do any math or modeling.
> 
> 
> - Terry



I have read other posts saying this same thing about fabrics. Are there any exceptions to this rule?


I just received fabric swatches from a company that makes acoustic absorption panels. My wife picked one but it really doesn't allow air to pass easily. It is a microsuede fabric. Even though the company uses this fabric, is it still acceptable?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Tom Cecc* /forum/post/18160876
> 
> 
> I have read other posts saying this same thing about fabrics. Are there any exceptions to this rule?
> 
> 
> I just received fabric swatches from a company that makes acoustic absorption panels. My wife picked one but it really doesn't allow air to pass easily. It is a microsuede fabric. Even though the company uses this fabric, is it still acceptable?



I have measured only one "microsuede" fabric, and it reflected 4 dB at 1 kHz. That's more than half the sound energy unabsorbed! So you end up wasting a lot of potentially efficient panel area.


I know, companies sell these as acoustic panel fabrics. But they don't necessarily know anything about them.


- Terry


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18162298
> 
> 
> I have measured only one "microsuede" fabric, and it reflected 4 dB at 1 kHz. That's more than half the sound energy unabsorbed! So you end up wasting a lot of potentially efficient panel area.
> 
> 
> I know, companies sell these as acoustic panel fabrics. But they don't necessarily know anything about them.



They point out how good they look and how they match the recliners.


----------



## Tom Cecc




> Quote:
> Originally Posted by *pepar* /forum/post/18162501
> 
> 
> They point out how good they look and how they match the recliners.



Exactly - They do look nice and match the sofa.







Figures that was the one she picked over the other style they sell: Jute burlap. It was already hard enough selling her on the panels.


Are there any better acoustical fabrics out there? I'm going to send for some Guilford swatches to see what their quality is like.


----------



## Terry Montlick




> Quote:
> Originally Posted by *Tom Cecc* /forum/post/18163419
> 
> 
> Are there any better acoustical fabrics out there? I'm going to send for some Guilford swatches to see what their quality is like.



I don't know about "better quality." Guilford FR701 is top quality, and has been used in commercial applications for many years.


As for other fabrics, Jo-Ann has a couple of them that rate high enough in acoustic transparency to be used as speaker grill cloth: their speaker grill cloth (duh!), but also their burlap. I can make no representation as to quality or safety. One thing you buy with Guilford FR701 is peace of mind. It has fire ratings up the wazoo.


----------



## adammb

I am setting up what to use for bass traps in my false soffits and also my acoustical panels. I have been looking for acoustical cotton batting and find it quite expensive. Can I use insulation instead?


Has anyone done this before. I am a bit concerned having it exposed in my room because its itchy but you wont be able to see any of it as it will be behind fabric.


Can anyone chime in on the differences between insulation and cotton batting?


----------



## Weasel9992




> Quote:
> Originally Posted by *adammb* /forum/post/18166653
> 
> 
> I am setting up what to use for bass traps in my false soffits and also my acoustical panels. I have been looking for acoustical cotton batting and find it quite expensive. Can I use insulation instead?
> 
> 
> Has anyone done this before. I am a bit concerned having it exposed in my room because its itchy but you wont be able to see any of it as it will be behind fabric.
> 
> 
> Can anyone chime in on the differences between insulation and cotton batting?



Insulation will work fine...preferably 4-6lbs mineral wool or Owens Corning 703. If you're covering it with fabric it'll be absolutely fine. There won't be any fiber migration to speak of.


Frank


----------



## Tom Cecc




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18165689
> 
> 
> I don't know about "better quality." Guilford FR701 is top quality, and has been used in commercial applications for many years.
> 
> 
> As for other fabrics, Jo-Ann has a couple of them that rate high enough in acoustic transparency to be used as speaker grill cloth: their speaker grill cloth (duh!), but also their burlap. I can make no representation as to quality or safety. One thing you buy with Guilford FR701 is peace of mind. It has fire ratings up the wazoo.



I'm going to try JoAnn's this weekend. The bad thing about their speaker cloth is the limited color choices. My wife liked the microsuede because she thought the burlap would be a "dust collector."










I can get a couple free swatches of the GOM. I will definitely check them out.

Thanks


----------



## adammb




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18166698
> 
> 
> Insulation will work fine...preferably 4-6lbs mineral wool or Owens Corning 703. If you're covering it with fabric it'll be absolutely fine. There won't be any fiber migration to speak of.
> 
> 
> Frank



I was more referring to actual insulation thats rolled like you put into the wall cavity. I am more asking for the false soffits. I would assume filling this with regular insulation would have a similar effect that cotton batting would have in a false soffit and also a riser that would be used as a bass trap.I think I'm going to play it safe with the side treatments and use cotton batting or OC703 4" thick. Although the cotton batting I find is only either 3 or 5" thick.


Also, if I was to use paper backed insulation I wouldnt have to put a paper backing on the bottom to keep the highs from getting soaked up.


Any suggestions on this?


----------



## Gertjan

If you have a drop ceiling, do bass traps in the wall-ceiling corners work well? Do bass waves go right through a drop ceiling, or does a wall-ceiling corner even with drop ceiling still focus the bass and is thus a viable place to put a bass trap?


----------



## Weasel9992




> Quote:
> Originally Posted by *Gertjan* /forum/post/18171272
> 
> 
> If you have a drop ceiling, do bass traps in the wall-ceiling corners work well? Do bass waves go right through a drop ceiling, or does a wall-ceiling corner even with drop ceiling still focus the bass and is thus a viable place to put a bass trap?



Yes, they still work. You're not wholly focused on tri-corner areas, so if you can't get all the way up to the hard ceiling then it's not the end of the world. Corner bass trapping still works well even with a drop ceiling.


Frank


----------



## Gertjan




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18182459
> 
> 
> Yes, they still work. You're not wholly focused on tri-corner areas, so if you can't get all the way up to the hard ceiling then it's not the end of the world. Corner bass trapping still works well even with a drop ceiling.



Since i have access to the space above the drop ceiling, and the joists run parallel to the wall i'm thinking off, would it be better to put the material above the drop ceiling perhaps? (Assuming enough space above the drop ceiling to put a bass trap of the same size.) I know there are no absolute answers, i'm just trying to understand how bass interacts with a drop ceiling- whether it mostly goes through it, or mostly gets reflected, or if it's 50-50, or... Thanks!


----------



## rdeyoung

Hey guys,


Just a quick question -


I visited Best Buy Magnolia Theater a couple times and noticed in one of the demo rooms, they have these big rectangular objects hanging on the wall. Its framed with wood, and has cloth in the middle. They are also shaped in a concave form, if you look at it from the side.


Can anyone explain to me what these do?


They seem to be at all the reflection points in the room. I was thinking about recreating these for my place, but I also was thinking about putting something on the inside of them such as "BMC" board from Ottawa Fibre Inc. (OFI). Or this other faced stuff called "FSK" to help with sound isolation, as to cut down sound from passing through walls. Im living in an apartment, so im looking into ways to help with acoustics, reflection areas, and sound isolation.


Thanks for everyones time.


----------



## eiger

Hi Guys,


I need some help as I continue on the path of treating my dedicated HT room. The image below illustrates my setup with 3 GIK 242s on each side wall.

Room is over 3000 cubit ft.


My room is slightly challenged due to half of the room being pergo (at ain stage) and asymetry from left and right front wall.


I've seen some immediate improvements in echo reflection with my current placements. I don't plan on building a dedicated screen wall, but what additional high priority treatments would you guys reccomend? I have considered putting additional panels behiind the left and right screen speakers. Would 242s or 244s be better here? My sub is located in back of room at the current time. I still get an extremely "live" sound from my main stage currently.


Any advice on next steps are appreciated.


----------



## Weasel9992




> Quote:
> Originally Posted by *eiger* /forum/post/18191303
> 
> 
> I've seen some immediate improvements in echo reflection with my current placements. I don't plan on building a dedicated screen wall, but what additional high priority treatments would you guys reccomend? I have considered putting additional panels behiind the left and right screen speakers. Would 242s or 244s be better here? My sub is located in back of room at the current time. I still get an extremely "live" sound from my main stage currently.



I'd do 244's there simply because you've got all 242's right now, so you could use some work down below 250Hz. It looks like you've got some space on the back wall, so a couple of 244's would be great there as well. Both of these additions will give you some low end control and knock down the roominess a bit as well.


Frank


----------



## eiger




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18192029
> 
> 
> I'd do 244's there simply because you've got all 242's right now, so you could use some work down below 250Hz. It looks like you've got some space on the back wall, so a couple of 244's would be great there as well. Both of these additions will give you some low end control and knock down the roominess a bit as well.
> 
> 
> Frank



Thanks Wesel. Couple of other q's.


1) I have a curtain that currently covers 3 small windows in the back which helps a bit. I don't have any real wall space there other than at the floor level. Does lining the wall with diffusers help in this situation, or are they only for very specific applications?


2) What is the general rule of thumb for applying tri-corner traps? Do they help in all coners of a room, or only where there is a sub near? I considered one in the right corner.


----------



## Weasel9992




> Quote:
> Originally Posted by *eiger* /forum/post/18192410
> 
> 
> Thanks Wesel. Couple of other q's.
> 
> 
> 1) I have a curtain that currently covers 3 small windows in the back which helps a bit. I don't have any real wall space there other than at the floor level. Does lining the wall with diffusers help in this situation, or are they only for very specific applications?
> 
> 
> You could always do 244's on stands if you want...diffusers are effective from about 500hz on up, so I suppose it really depends on what kind of problems you're actually experiencing. If it's just that the room is too live, then absorption is really the way you need to go.
> 
> 
> 2) What is the general rule of thumb for applying tri-corner traps? Do they help in all coners of a room, or only where there is a sub near? I considered one in the right corner.



They help in all corners of the room, but it's important that they be applied as symmetrically as possible. In your case you have two unavailable corners diametrically opposed to one another. You could trap wall/ceiling corners...


Frank


----------



## rdeyoung




> Quote:
> Originally Posted by *rdeyoung* /forum/post/18190000
> 
> 
> Hey guys,
> 
> 
> Just a quick question -
> 
> 
> I visited Best Buy Magnolia Theater a couple times and noticed in one of the demo rooms, they have these big rectangular objects hanging on the wall. Its framed with wood, and has cloth in the middle. They are also shaped in a concave form, if you look at it from the side.
> 
> 
> Can anyone explain to me what these do?
> 
> 
> They seem to be at all the reflection points in the room. I was thinking about recreating these for my place, but I also was thinking about putting something on the inside of them such as "BMC" board from Ottawa Fibre Inc. (OFI). Or this other faced stuff called "FSK" to help with sound isolation, as to cut down sound from passing through walls. Im living in an apartment, so im looking into ways to help with acoustics, reflection areas, and sound isolation.
> 
> 
> Thanks for everyones time.



bump for my question too please.


----------



## Zen Traveler




> Quote:
> Originally Posted by *rdeyoung* /forum/post/18195047
> 
> 
> bump for my question too please.


 http://www.realtraps.com/products.htm


----------



## Redskin

Hi all,


I am VERY new to any kind of acoustic treatments, and am working my way through this thread. I have a small dedicated room in my basement, mostly home theater. It is a pretty small space, about 1400 cubic feet. Sealed space, front projector.


My biggest question/concern is my first reflection points. On my left side, I have glass french doors, and on my right side I have a window at the first reflection points for my main seating positions. I don't have a lot of options. I was thinking about putting up some heavy velvet drapes on each side, which I guess will help some with the highs. Another option would be to push the L/C/R speakers up against the front wall, which would move the first reflection off of the glass structures and at a wall point, which I could put up some panels.


Is it better to position the speakers as they are, 4' out into the room, treat the windows with drapes, and put panels and traps in other places throughout the room, or compromise the speaker location, putting them against the front wall to allow for a proper panel at the first reflection points?


Thanks!

Greg


----------



## The_Nephilim1




> Quote:
> Originally Posted by *The_Nephilim1* /forum/post/18150265
> 
> 
> Hi, Looking to improve my Room Acoustics as they are probally needed.. All I have availble is a SPL Meter along with a Test Tones CD. Will I be able to test my room with that or do I need a Fancy Gizmo to do the readings??
> 
> 
> Here is a Pic of my Room it is in the Basement with the Right and Rear wall being Cynderblocks with Drywall over... On the Front and Left Wall When I built it I put in 2" Insulation between the Studs to the Ceiling, the Styrofoam kind of Insulation..
> 
> 
> Would Someone be able to tell me what to Add or do I need to make Measurments first??
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> By the_nephilim at 2010-02-16
> 
> 
> 
> 
> Also here is my Webpage with some Before and after shots. Also I havea 7' Drop ceiling and did NOT put any insulation inbetween the Joists above the ceiling Should I??
> 
> 
> http://home.comcast.net/~glafsr/wsb/...ome.html-.html



Any Hope or Help..I would really appreciate it ..


----------



## Ethan Winer




> Quote:
> Originally Posted by *The_Nephilim1* /forum/post/18150265
> 
> 
> Hi, Looking to improve my Room Acoustics as they are probally needed.. All I have availble is a SPL Meter along with a Test Tones CD. Will I be able to test my room with that or do I need a Fancy Gizmo to do the readings??



Your questions aren't very specific, so here's some general advice on room measuring (and below that) room treatment:

All About SPL Meters 

Room EQ Wizard, Windows and Linux and Mac OSX 10.4+, Freeware 
ETF, Windows, $150 
FuzzMeasure, Mac, $150 
Using ETF explains how I use ETF, but the principles apply to all such programs.
Comparison of Ten Measuring Microphones 

Acoustic Basics 
How to set up a room 

RealTraps Articles 
RealTraps Videos 


--Ethan


----------



## dweltman

I am planning to put corner loaded bass traps in the front corners of my listening room. They are expensive, but I am wondering about the relative benefit of treating the front corners from floor to ceiling. I could buy 4' high traps, or go the whole 8'. Will I notice the difference?


----------



## nathan_h




> Quote:
> Originally Posted by *dweltman* /forum/post/18220520
> 
> 
> Will I notice the difference?



There will be almost assuredly be a measurable difference.


Will you notice it? There is only one way to find out. Certainly, many people with an ear for audio reproduction would notice it.


Without knowing the rest of the system and room, it's hard to judge -- even excepting for differences in individual perception and experience.


----------



## pepar




> Quote:
> Originally Posted by *dweltman* /forum/post/18220520
> 
> 
> I am planning to put corner loaded bass traps in the front corners of my listening room. They are expensive, but I am wondering about the relative benefit of treating the front corners from floor to ceiling. I could buy 4' high traps, or go the whole 8'. Will I notice the difference?



Here's what I have ... and I'm adding more ....


----------



## hdash

I moved into a new (to me) house and tried to recreate my living room layout as best I can in the below picture, prior to my PR-SC5507 arriving Wed. The room is an open 2 story room and I am hoping to tame this room a little and on a very tight budget (due mostly to the new pre-pro). If I can only afford to spend on either heavy curtains shown as blue lines over the windows with faux wood blinds at the top of the layout or a few acoustic panels in the areas marked with green lines, what would you do? I am also of course open to any giudance and suggestions.



















Links to Picasa posted pictures

http://picasaweb.google.com/hdkash/E...24787087606578 
http://picasaweb.google.com/hdkash/E...57776920064562 


Thanks


----------



## The_Nephilim1




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18217178
> 
> 
> Your questions aren't very specific, so here's some general advice on room measuring (and below that) room treatment:
> 
> All About SPL Meters
> 
> Room EQ Wizard, Windows and Linux and Mac OSX 10.4+, Freeware
> ETF, Windows, $150
> FuzzMeasure, Mac, $150
> Using ETF explains how I use ETF, but the principles apply to all such programs.
> Comparison of Ten Measuring Microphones
> 
> Acoustic Basics
> How to set up a room
> 
> RealTraps Articles
> RealTraps Videos
> 
> 
> --Ethan






Hi, Thnx for the links that should answer my Question.. Not to start and argument with you but I did ask a specific Question..


I had stated I have a SPL Meter and a Test Tone CD.. I then asked will I be able to test my room with the SPL Meter & Test CD I have or do I need a Fancy Frequencey measuring device???


So can I measure my Room with just a SPL Meter & Test Tone CD to find what kind of Acoustic treatment is needed for my Room??


----------



## pepar




> Quote:
> Originally Posted by *The_Nephilim1* /forum/post/18225615
> 
> 
> Hi, Thnx for the links that should answer my Question.. Not to start and argument with you but I did ask a specific Question..
> 
> 
> I had stated I have a SPL Meter and a Test Tone CD.. I then asked will I be able to test my room with the SPL Meter & Test CD I have or do I need a Fancy Frequencey measuring device???
> 
> 
> So can I measure my Room with just a SPL Meter & Test Tone CD to find what kind of Acoustic treatment is needed for my Room??



Well, yes, that is what the Test Tone CD is for - measuring with a sound level meter. The first link Ethan posted explains the process. The other links he posted are for bonus points.


Some of us here are of the "teach them to fish" school of thinking.










Jeff


----------



## Glenn Baumann




> Quote:
> Originally Posted by *pepar* /forum/post/18221855
> 
> 
> Here's what I have ... and I'm adding more ....




Pepar,


Do you plan on treating that maroon colored drywall at the back of your false wall with linacoustic or anything...is it needed?


By the way, nice superchunk bass traps! I bet they are really effective, yes?



...Glenn


----------



## pepar




> Quote:
> Originally Posted by *Glenn Baumann* /forum/post/18226785
> 
> 
> Pepar,
> 
> 
> Do you plan on treating that maroon colored drywall at the back of your false wall with linacoustic or anything...is it needed?
> 
> 
> By the way, nice superchunk bass traps! I bet they are really effective, yes?
> 
> 
> ...Glenn



Glenn, this pic was taken during the addition of those SuperChunk traps. If you follow the home theater upgrade link in my sig, you will find the whole construction and upgrade process. Adding the traps made an incredible difference in my theater not just in the bottom end, but the entire range by cleaning up the ringing that had been masking the higher frequency content.


Yes, there is 2" of Johns-Manville Linacoustic RC on that wall during normal use.




Jeff


----------



## nathan_h




> Quote:
> Originally Posted by *hdash* /forum/post/18223895
> 
> 
> I moved into a new (to me) house and tried to recreate my living room layout as best I can in the below picture, prior to my PR-SC5507 arriving Wed. The room is an open 2 story room and I am hoping to tame this room a little and on a very tight budget (due mostly to the new pre-pro). If I can only afford to spend on either heavy curtains shown as blue lines over the windows with faux wood blinds at the top of the layout or a few acoustic panels in the areas marked with green lines, what would you do? I am also of course open to any giudance and suggestions.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Links to Picasa posted pictures
> 
> http://picasaweb.google.com/hdkash/E...24787087606578
> http://picasaweb.google.com/hdkash/E...57776920064562
> 
> 
> Thanks



Interesting. I'd be real tempted to put the TV where the loveseat is. That would give you more space on the left and right, and even space on the sides -- symmetry is key. It would also let you pull the seats a little further into the room.


Then some heavy (very heavy) curtains would help with the parallel walls in front/behind.


-----


If you want to stay with you current layout, being so close to one side wall is always going to a problem. Heavy curtains may help, but you have a severe lack of symmetry with the other side wall.


The idea of panels on the rear behind you, in your proposed setup, is very good.


----------



## Ethan Winer




> Quote:
> Originally Posted by *The_Nephilim1* /forum/post/18225615
> 
> 
> will I be able to test my room with the SPL Meter & Test CD I have or do I need a Fancy Frequencey measuring device???



It's like saying I have a bicycle now, and asking if I need a car to go to the supermarket. Sorry, I was tired.







The longer answer is an SPL meter and test tone CD can show you the raw response, but none of the time-based problems. It also depends on the test CD. Most have sine waves at third-octave intervals which is useless for assessing bass response. The RealTraps Test Tone CD at the RealTraps site is much better in that regard, but it still shows only the raw response. So if you really want to understand what's going on in your room, you'll need proper software like those I linked to.


--Ethan


----------



## mike2060

I was wonder, at what dimensions do room modes not matter much? 40 feet? 100 feet?


----------



## kevinzoe




> Quote:
> Originally Posted by *mike2060* /forum/post/18227732
> 
> 
> I was wonder, at what dimensions do room modes not matter much? 40 feet? 100 feet?



Mike - by "not matter much" can I assume that you mean that the modes are inaudible, hence not a problem? Is so, then using 20Hz as the lowest freq that we can audibly hear (not feel), would mean a 28.25 foot dimension will have it's first axial mode at 20Hz calculated as 1130/(2*28.25).


Of course its 2nd and subsequent modes will be at 40, 60Hz etc which may be more (less) audible if constructive (destructive) interference causes a peak (null). All this is theoretical and may differ from our residential rooms due to boundary material used and their reflecting (e.g. cinder block) or absorbing (e.g. drywall) characteristics.


The larger the dimensions the lower the Schroeder/transitional frequency will become so build your music/HT 'man cave' as large as possible!


----------



## hdash

Thanks nathan_H, solid advice as I expected frm the folks here.

I tought about trying to rotate the layout but it bunched everything next to the fireplace and the room was already wired for speakers (where the Aplhas are about 12ft up th wall),so I am doing the best I can given what I have and I am leasing. If I could ony close of the room its in making a nice rectagular room above it.

I will get some heavy curtains put up a build a couple of panels to hang on the back wall


----------



## mike2060




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18231157
> 
> 
> Mike - by "not matter much" can I assume that you mean that the modes are inaudible, hence not a problem? Is so, then using 20Hz as the lowest freq that we can audibly hear (not feel), would mean a 28.25 foot dimension will have it's first axial mode at 20Hz calculated as 1130/(2*28.25).
> 
> 
> Of course its 2nd and subsequent modes will be at 40, 60Hz etc which may be more (less) audible if constructive (destructive) interference causes a peak (null). All this is theoretical and may differ from our residential rooms due to boundary material used and their reflecting (e.g. cinder block) or absorbing (e.g. drywall) characteristics.
> 
> 
> The larger the dimensions the lower the Schroeder/transitional frequency will become so build your music/HT 'man cave' as large as possible!



Thanks!


----------



## Dennis Erskine

...Kevin....I disagree. The room must be larger to provide the results you're suggesting and having a 20Hz null in the center of the room is not all that popular. 236" from the front wall ... you'd need some serious LCRs to handle that distance.


----------



## kevinzoe




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18233433
> 
> 
> ...Kevin....I disagree. The room must be larger to provide the results you're suggesting and having a 20Hz null in the center of the room is not all that popular. 236" from the front wall ... you'd need some serious LCRs to handle that distance.




Dennis - as one of the local pro's here, I will defer to your expertise, so could you kindly expand upon your point(s) above for all?

* Is my logic incorrect? Are you suggesting that 20Hz should not be the 1st mode but rather some higher multiple of it instead? E.g. if 20Hz is the 2nd mode then the dimension length should aim to have 10hz as its 1st mode.

* Is my math incorrect?

* 20Hz null in centre of room -> assuming someone sits in the middle of the room (which I would tend to doubt for music but perhaps HT), yes a null would be bad but wouldn't multiple subs ameliorate the problem? Are you suggesting moving the 20Hz null closer to the back wall so hence a longer dimension, similar to my point above by using 20Hz as the 2nd mode not the 1st mode?


thanks in advance,

kevin


----------



## nathan_h




> Quote:
> Originally Posted by *hdash* /forum/post/18232312
> 
> 
> Thanks nathan_H, solid advice as I expected frm the folks here.
> 
> I tought about trying to rotate the layout but it bunched everything next to the fireplace and the room was already wired for speakers (where the Aplhas are about 12ft up th wall),so I am doing the best I can given what I have and I am leasing. If I could ony close of the room its in making a nice rectagular room above it.
> 
> I will get some heavy curtains put up a build a couple of panels to hang on the back wall



I think your plan is reasonable. And having wiring already in place is nice.


About this comment: "bunched everything next to the fireplace", remember, you don't need to put the equipment rack and the sub on that wall next to the fireplace -- just the display and the L and R speakers. Even so, it may not be workable, but I thought I should mention it.


----------



## The_Nephilim1




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18227694
> 
> 
> It's like saying I have a bicycle now, and asking if I need a car to go to the supermarket. Sorry, I was tired.
> 
> 
> 
> 
> 
> 
> 
> The longer answer is an SPL meter and test tone CD can show you the raw response, but none of the time-based problems. It also depends on the test CD. Most have sine waves at third-octave intervals which is useless for assessing bass response. The RealTraps Test Tone CD at the RealTraps site is much better in that regard, but it still shows only the raw response. So if you really want to understand what's going on in your room, you'll need proper software like those I linked to.
> 
> 
> --Ethan




OK THNX. That is what I thought.. will look over the links you sent me..


OK If I used the Rolls of Insulation for a Bass Trap what kind of Material can I encase it in for appearence ??


I am learning thnx fro those links,I am reading them all now..


----------



## Weasel9992




> Quote:
> Originally Posted by *The_Nephilim1* /forum/post/18237345
> 
> 
> OK If I used the Rolls of Insulation for a Bass Trap what kind of Material can I encase it in for appearance ??



Anything acoustically transparent...burlap works perfectly, or you can go with Guilford of Maine FR701 if you want something nicer. There are a million options.


Frank


----------



## dweltman

So my room has several large windows and in conjunction with a 60" plasma and other items is relatively live. We live in the woods, and like natural light during the day. So my wife will probably not go for heavy curtains or drapes, best I could probably do is shades. I realize there is not much you can do absorption wise with shades, but any suggestions on a shade type or material that would somewhat ameliorate the reflectivity of the windows? One of the windows is at a first reflection point, so it is really problematic.


----------



## Weasel9992

I don't know of anything that would add an absorptive element. Well, that's not true...I once saw 48" vertical blinds trimmed in pink fur in a girl's dorm room in college, but I doubt your wife would be down with that.







2" horizontal wood blinds can add a diffusive element, but that's not my favorite thing to do at reflection points.


Frank


----------



## dweltman




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18253853
> 
> 
> I don't know of anything that would add an absorptive element. Well, that's not true...I once saw 48" vertical blinds trimmed in pink fur in a girl's dorm room in college, but I doubt your wife would be down with that.
> 
> 
> 
> 
> 
> 
> 
> 2" horizontal wood blinds can add a diffusive element, but that's not my favorite thing to do at reflection points.
> 
> 
> Frank



Thanks for your early morning reply, Frank. No I don't think pink fur will work for us! Sorry to hear you don't know of any satisfactory solutions for my problem







Anybody else have any ideas? In searching the web this morning, RPG has this:

http://www.rpginc.com/residential/pd...Brochure2t.pdf 


Has anyone tried it? Marketing hype or useful product?


----------



## Dennis Erskine

You can look at AcoustiShades from Stewart Film ( www.stewartfilm.com ). You'll find them under Residential/Products/Special Applications. First reflections are not bad unless your speakers have horrible off axis response.


----------



## dweltman




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18254007
> 
> 
> You can look at AcoustiShades from Stewart Film ( www.stewartfilm.com ). You'll find them under Residential/Products/Special Applications. First reflections are not bad unless your speakers have horrible off axis response.



My speakers are B&W 802D's. I thought after bass trapping, first reflections were the next most important things to address?


----------



## johnbomb

I'll bet this has been addressed in one way, shape, or form, but just in case it hasn't, I'd really like to hear what our local experts have to say about this:

http://www.audioholics.com/education...nt-perspective


----------



## Dennis Erskine

Ah...not certain what you're looking for here. Yes, fabric over fuzz applied to walls reflects a lot of the early reflections. Yes, early reflections can enhance sound quality and dialog intellibility, yes for hard reflections (close to a wall), diffusion is a good thing, and yes most people over absorb and yes many speaker manufacturer's don't give a twit about off axis response quality and yes, if the off axis response is bad, you don't want that "bad" sound reflected all over the room. And, why do you suppose you'll never get a polar response plot, or off axis response plot from B&W?


----------



## Dennis Erskine

Ok...I opened the can of worms about off axis FR plots being "unavailable". Just try and get these things from manufacturers of consumer market gear (even worse, don't even think of asking boutique speaker manufacturers for this stuff). The absolute, only reason for not providing this information is because they know something they don't want you to know. Here are the excuses:


1. We don't measure that. (translation: we don't have a clue how our speakers perform but if you want real answers, talk to the marketing department).

2. We don't provide that information to consumers because they wouldn't understand it. (Translation: you and I are all stupid.)

3. None of customers would ever listen off axis. (Translation: They don't have a clue about in room acoustics OR all of their customers should be listening to their speakers in a freshly harvested wheat field.)

4. What are those? (real answer from a "high end" speaker designer selling really, really expensive two-channel audiophile speakers).

5. Our dealers wouldn't know what to do with them. (Translation: would you buy a speaker from this guy? Alternate translation: don't have 'em, never had 'em and our measurement equipment has been broken since 1970 and never fixed..besides, Mr. A's ears are better than any testing equipment.)


What about "THX" speakers. You may not like THX. You may not like THX speakers. You do know that an independent third party measured everything that can possibly be measured and it passed over their bar. (As far as I can determine, THX testing is on par with, or costs less than the same level of testing provided by other third party labs.)


----------



## giomania

Dennis,


Since you opened the (off-axis response) can of worms, what speakers manufacturers do you recommend? I ask because if this information is unobtainable, how are we supposed to choose speakers with decent or better off-axis response? Did I understand that you are saying THX certified speakers might be a decent option?


Thanks for any info you are willing to divulge.


Mark


----------



## Terry Montlick

6. If we gave you complete polar responses for our speakers, it would reveal them to be imperfect. I had one very high end (read "very expensive") speaker's engineer share some of his off-axis data with me. He was quickly overruled by management, and was forbidden to talk with me again.


----------



## Dennis Erskine




> Quote:
> Did I understand that you are saying THX certified speakers might be a decent option?



If you cannot measure the speakers yourself (accurately), then you know that a THX certified speaker has at least crossed their minimum acceptable (which is rather high) bar...which includes of axis response. This does not mean there are very good speakers which do not have THX testing, nor does it mean all THX speakers are appropriate for all rooms. What else can be said about THX testing? At least the manufacturer cared enough about their product's performance to get a third party opinion.


To Terry's experience, I measured a set of speakers and then called to ask whether I had a bad example or otherwise what was going on. The formal response came from their outside counsel suggesting my publication of that information would result in some very expensive legal fees. (I get a similar 'proforma' letter annually from a supplier (manufacturer) of a mass loaded vinyl product.)


----------



## mike2060

JBL has off axis data, at least in their pro lines.


Also:

http://www.soundstageav.com/speakermeasurements.html


----------



## Dennis Erskine

Virtually all Pro speakers have axis data available. (Actually, I don't know of any pro speakers which do not.)


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18265427
> 
> 
> Virtually all Pro speakers have axis data available. (Actually, I don't know of any pro speakers which do not.)



Would you say that speakers without this testing would not be taken seriously by professionals?


----------



## jamin

The pro space modeling programs are set up to use databases of speaker 3-d response data. The major competitive pro speaker maufacturers provide this data for these databases.


No real way to honestly consider them otherwise.


I guess the old standbys are available-

Looks

Price

"You know who" likes/uses them

and the ever popular "Trust your ears"


----------



## highlife

Has anyone heard or or used this product? It's use is stated on their site as:


Sound absorption in theaters, studios, and entertainment facilities.

For applications requiring a black, sound absorbing insulation.


The manufacturer is CertainTeed. I searched this forum and found nothing, but it looks like it may be a good solution for behind-screen-wall cavities.

http://www.certainteed.com/products/...--rolls/317352


----------



## cuzed2

Looks to be very similar to JM Linacoustic. If so should be great for front wall(s).

I assume it comes in 1" and 2" varieties.


Hopefully others will chime in to confirm


----------



## Weasel9992




> Quote:
> Originally Posted by *highlife* /forum/post/18285502
> 
> 
> Has anyone heard or or used this product?



What specifically do you want to do with it? I agree with the previous poster that it would be great for the screen wall or even reflection points if the room is large enough.


Frank


----------



## yacht422

frank: what would you be considering when you say large enough?

thx

walt


----------



## highlife




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18286084
> 
> 
> What specifically do you want to do with it? I agree with the previous poster that it would be great for the screen wall or even reflection points if the room is large enough.
> 
> 
> Frank



I am considering using it behind my screen in a 3 x 15 area, covering up concrete block and providing sound absorption. I am guessing it is more economical than 2 x 4 panels or OC, very flexible and easy to work with. It is offered in 1, 1 1/2 and 2 inch versions.


----------



## eiger

I'm looking at some GIK 242s. I only need 2 of them. Not 3.


Anyone know why one must order 3 per box? Are they flexible on that?


----------



## dc_pilgrim

Ask them, not us?


----------



## Weasel9992




> Quote:
> Originally Posted by *yacht422* /forum/post/18287094
> 
> 
> frank: what would you be considering when you say large enough?
> 
> thx
> 
> walt



*VERY GENERALLY SPEAKING*, 17'x20'x8 or larger.


Frank


----------



## yacht422




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18292654
> 
> 
> *VERY GENERALLY SPEAKING*, 17'x20'x8 or larger.
> 
> 
> Frank



would this material be effective behind non a/t screens?

walt


----------



## johnbomb




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18257098
> 
> 
> Ah...not certain what you're looking for here. Yes, fabric over fuzz applied to walls reflects a lot of the early reflections. Yes, early reflections can enhance sound quality and dialog intellibility, yes for hard reflections (close to a wall), diffusion is a good thing, and yes most people over absorb and yes many speaker manufacturer's don't give a twit about off axis response quality and yes, if the off axis response is bad, you don't want that "bad" sound reflected all over the room. And, why do you suppose you'll never get a polar response plot, or off axis response plot from B&W?



Thanks for the response, Dennis. What do you think about the discussion of RT60 times?


----------



## kevinzoe




> Quote:
> Originally Posted by *eiger* /forum/post/18291836
> 
> 
> I'm looking at some GIK 242s. I only need 2 of them. Not 3.
> 
> 
> Anyone know why one must order 3 per box? Are they flexible on that?





As a GIK customer I can tell you that 3 242s will fit within their chosen box size but you can buy just 1 or 2 if you wish . . .


Dr. Floyd Toole recommends a minimum absorption depth of 4" so perhaps their 244 or Monster trap may be a better way to go so that your frequency balance isn't thrown out of balance by only attenuating the high frequencies.


----------



## rdeyoung

*HEY GUYS!*


Quick question about noise canceling. I just moved into an apartment that is on the second floor (and has a loft), and I was wondering how I can cancel out some noise coming from another apartment and also from the apartment below me.

*Question #1:* I have a set of Paradigm Studio 100s and im nervous about bothering the people below me. What steps can I take to help that out? I have carpet flooring, not wood - which I know helps in dampening...

_*Question #2:*_ My bedroom wall happens to be lined up next to a kid's bedroom...a very young kid's bedroom - who sometimes throws a fit. What can I do to stop the noise from penetrating through this wall that doesn't involve tearing out the drywall and replacing the insulation with better stuff?



Thanks for your help in advance!


----------



## Elill

Anyone else tried to get off axis data out of their manufacturer this week?...I'd been wanting it for ages, but this recent discussion prompted me to ask....they're pretty much ignoring me now....


.....and I have what I regard to be pretty darn good speakers, its quite annoying, it'd make life much easier if I could allow for certain things (treatments) during construction....I wonder if they know the data or not or if its just really bad, which I suppose I dont want to know given how much coin I've sunk into the things


----------



## Johnnycloud

I read about a technique where you can use a mylar strip to determine where sound from your speakers is reflecting off the wall. You put a light source, such as a lamp without a shade, where the speakers normally sit. Then the place you can see the light on the mylar strip is where the sound reflects off the wall. This then would be where you would place the treatment. The problem I am having is that I cannot find the mylar material anywhere. I have checked the local craft stores and wal-marts. Does anyone know if regular metallic-type paper used for wrapping presents or as bows could be used for this? Or does it require mylar specifically for this to work?


----------



## erkq




> Quote:
> Originally Posted by *Johnnycloud* /forum/post/18302588
> 
> 
> I read about a technique where you can use a mylar strip to determine where sound from your speakers is reflecting off the wall. You put a light source, such as a lamp without a shade, where the speakers normally sit. Then the place you can see the light on the mylar strip is where the sound reflects off the wall. This then would be where you would place the treatment. The problem I am having is that I cannot find the mylar material anywhere. I have checked the local craft stores and wal-marts. Does anyone know if regular metallic-type paper used for wrapping presents or as bows could be used for this? Or does it require mylar specifically for this to work?



Don't over-complicate it. Just use a mirror!


----------



## kevinzoe




> Quote:
> Originally Posted by *Johnnycloud* /forum/post/18302588
> 
> 
> I read about a technique where you can use a mylar strip to determine where sound from your speakers is reflecting off the wall. You put a light source, such as a lamp without a shade, where the speakers normally sit. Then the place you can see the light on the mylar strip is where the sound reflects off the wall. This then would be where you would place the treatment. The problem I am having is that I cannot find the mylar material anywhere. I have checked the local craft stores and wal-marts. Does anyone know if regular metallic-type paper used for wrapping presents or as bows could be used for this? Or does it require mylar specifically for this to work?




Johnny - you're making it too difficult for yourself - forget the mylar strip and get a hand held mirror instead, and an assistant. Sit yourself in your listening position chair and have your assistant slowly move the mirror across the wall starting next to the speaker and moving horizontally towards the back wall at tweeter height. You should see the speaker closest to the side wall first and a short distance away you'll see the speaker across the room. Each side wall has 2 1st reflection points.


Before you spend money foolishly, buy Dr Floyd Toole's latest book to educate yourself on acoustics and room treatments so you don't waste money putting the 'wrong' treatment up. Depending on if you're a HT or stereo listening person the teatment may vary . . .


----------



## gravi

I bougt some corner bass traps and am planning to straddle the front corners, just sitting on the floor. I have drapes, velvet-type material covering the front walls. Can I place the traps behind the drapes, or outside, or does it matter?


----------



## kevinzoe




> Quote:
> Originally Posted by *gravi* /forum/post/18302809
> 
> 
> I bougt some corner bass traps and am planning to straddle the front corners, just sitting on the floor. I have drapes, velvet-type material covering the front walls. Can I place the traps behind the drapes, or outside, or does it matter?



Gravi - What kind of corner bass traps did you get as the kind of trap (i.e. helmholtz, diaphragmatic, resistive) will determine how to properly set them up for max effectiveness. . .


The bass frequencies won't "see" the velvet draps so putting the bass traps behind them is fine, depending on what kind they are. Which brand and model did you buy will help us know more.


----------



## Speedskater

You don't even need a mirror!

You can use a Lazar Level or Lazar podium pointer. It will reflect off most painted walls. Sit in the listening positions and aim it to reflect off the wall towards the speakers.


----------



## Johnnycloud




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18302647
> 
> 
> Johnny - you're making it too difficult for yourself - forget the mylar strip and get a hand held mirror instead, and an assistant. Sit yourself in your listening position chair and have your assistant slowly move the mirror across the wall starting next to the speaker and moving horizontally towards the back wall at tweeter height. You should see the speaker closest to the side wall first and a short distance away you'll see the speaker across the room. Each side wall has 2 1st reflection points.
> 
> 
> Before you spend money foolishly, buy Dr Floyd Toole's latest book to educate yourself on acoustics and room treatments so you don't waste money putting the 'wrong' treatment up. Depending on if you're a HT or stereo listening person the teatment may vary . . .



thanks for the help.


----------



## gravi




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18302929
> 
> 
> Gravi - What kind of corner bass traps did you get as the kind of trap (i.e. helmholtz, diaphragmatic, resistive) will determine how to properly set them up for max effectiveness. . .
> 
> 
> The bass frequencies won't "see" the velvet draps so putting the bass traps behind them is fine, depending on what kind they are. Which brand and model did you buy will help us know more.



They are fiberglass 4 inch thick traps. I bought the at www.acoustimac.com - good site, I liked them. They are basically rectangulat 2' by 2' but has tapered sides to fit against a wall corner. I can easily conceal them behind the draft. I see your point about bass frequencies but curious about higher frequencies and how they would behave.


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18302647
> 
> 
> 
> Before you spend money foolishly, buy Dr Floyd Toole's latest book to educate yourself on acoustics and room treatments so you don't waste money putting the 'wrong' treatment up. Depending on if you're a HT or stereo listening person the teatment may vary . . .



Can you name three or four people other than Dr Toole who shares his position on first and early lateral reflections?


----------



## mike2060

Well most of the people who think early reflections are bad are the people profiting off of it...


Also Toole is just going by his research, not personal opinion. But he doesn't say that attenuating first reflections is bad, he just says that you can if you want, but there are no real downsides to leaving them reflective, only upsides. I would suggest reading his book and deciding for yourself. I think you can find it on Google Books or on Harman's site (not his book but a research paper).


----------



## Ethan Winer




> Quote:
> Originally Posted by *mike2060* /forum/post/18304168
> 
> 
> there are no real downsides to leaving them reflective, only upsides.



In the graph below, which frequency response would you prefer?


--Ethan


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18304814
> 
> 
> In the graph below, which frequency response would you prefer?



Well, if I listened to graphs, the answer is clear.










However, I suspect that this test compared flat, unadorned, completely reflective side-walls with fairly-well treated, absorbent ones. This is certainly demonstrative but extreme, imho. Most cases fall in between these extremes. In addition, the use of wall-hangings and decorations can provide diffusion (rather than absorption) and ameliorate what you demonstrate.


Also, Toole's statements are based, not only on measurements, but on statistical samplings of listener opinion and, even then, he is not dismissive of treating the sidewalls. He discusses a trade-off in imaging specificity for soundstage width and immersion and this trade-off spans the continuum between what I assume are the two extremes you tested.


Another variable is the radiation characteristic of the speakers.


So, I do not think that this is a situation in which all the "right" is on either side.


----------



## yacht422




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18304883
> 
> 
> Well, if I listened to graphs, the answer is clear.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> However, I suspect that this test compared flat, unadorned, completely reflective side-walls with fairly-well treated, absorbent ones. This is certainly demonstrative but extreme, imho. Most cases fall in between these extremes. In addition, the use of wall-hangings and decorations can provide diffusion (rather than absorption) and ameliorate what you demonstrate.
> 
> 
> Also, Toole's statements are based, not only on measurements, but on statistical samplings of listener opinion and, even then, he is not dismissive of treating the sidewalls. He discusses a trade-off in imaging specificity for soundstage width and immersion and this trade-off spans the continuum between what I assume are the two extremes you tested.
> 
> 
> Another variable is the radiation characteristic of the speakers.
> 
> 
> So, I do not think that this is a situation in which all the "right" is on either side.



radiation = off axis performance??


----------



## Kal Rubinson




> Quote:
> Originally Posted by *yacht422* /forum/post/18305304
> 
> 
> radiation = off axis performance??



Yes, unless you are considering something nuclear.


----------



## beatboy77

Would 1/2" Linacoustic be acceptable for walls?


~Josh


----------



## nathan_h

Generally, you don't want to cover "the walls" but hit the "first reflection points" and thicker is better, say 4 inches, to get coverage of more frequencies, without making the room too dead.


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18304168
> 
> 
> Well most of the people who think early reflections are bad are the people profiting off of it...
> 
> 
> Also Toole is just going by his research, not personal opinion. But he doesn't say that attenuating first reflections is bad, he just says that you can if you want, but there are no real downsides to leaving them reflective, only upsides. I would suggest reading his book and deciding for yourself. I think you can find it on Google Books or on Harman's site (not his book but a research paper).



I have read it (and I have an opinion based on my own experience). I am asking if you can cite two or three other researchers whose data is telling them that first lateral reflections are good in a multichannel home theater.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18304883
> 
> 
> I suspect that this test compared flat, unadorned, completely reflective side-walls with fairly-well treated, absorbent ones.



Yes, I measured this in my living room with and without absorbers at the side-wall reflection points.



> Quote:
> Toole's statements are based, not only on measurements, but on statistical samplings of listener opinion



I understand, but I don't know if the listeners were sophisticated or random. A lot of the "general public" will prefer a "smiley face" EQ curve, for example.


--Ethan


----------



## belzarrath

A quick question if possible. I am picking out carpet for my HT.

What are the most important things I need to be concerned about?

Type of carpet ( deep pyle, shagg, etc.)

Pad, thickness and type.

I am limited here sense moisture may be a problem.


----------



## erkq




> Quote:
> Originally Posted by *belzarrath* /forum/post/18319542
> 
> 
> A quick question if possible. I am picking out carpet for my HT.
> 
> What are the most important things I need to be concerned about?
> 
> Type of carpet ( deep pyle, shagg, etc.)
> 
> Pad, thickness and type.
> 
> I am limited here sense moisture may be a problem.



Nothing to do with acoustics, but DARK!


----------



## mike2060




> Quote:
> Originally Posted by *belzarrath* /forum/post/18319542
> 
> 
> A quick question if possible. I am picking out carpet for my HT.
> 
> What are the most important things I need to be concerned about?
> 
> Type of carpet ( deep pyle, shagg, etc.)
> 
> Pad, thickness and type.
> 
> I am limited here sense moisture may be a problem.



Floyd Toole recommends clipped-pile carpet with 40oz/sq yd felt underlay.


----------



## pepar




> Quote:
> Originally Posted by *pepar* /forum/post/18308124
> 
> 
> I have read it (and I have an opinion based on my own experience). I am asking if you can cite two or three other researchers whose data is telling them that first lateral reflections are good in a multichannel home theater.





> Quote:
> Originally Posted by *mike2060* /forum/post/18320011
> 
> 
> Floyd Toole recommends clipped-pile carpet with 40oz/sq yd felt underlay.



How's it going, mike2060, on finding two or three researchers other than Toole who think lateral first reflections in a multichannel home theater are a good thing?


----------



## mike2060




> Quote:
> Originally Posted by *pepar* /forum/post/18320227
> 
> 
> How's it going, mike2060, on finding two or three researchers other than Toole who think lateral first reflections in a multichannel home theater are a good thing?



I don't know of many other researchers in this industry. I do know that Toole has used data from experiments done over the last 30-40 years though. He doesn't pull this stuff out of his ass. Let me guess, you must be like 60 years old because old people NEVER change their opinions.


How about this? Show ME two or three people who actually have research backing them up saying first reflections are bad. You seem to be the one without someone credible backing them up (And no, Ethan Winer's graph doesn't count as one as it's certainly not enough proof).


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18320745
> 
> 
> I don't know of many other researchers in this industry. I do know that Toole has used data from experiments done over the last 30-40 years though. He doesn't pull this stuff out of his ass. Let me guess, you must be like 60 years old because old people NEVER change their opinions.



I will be 60 in June. But it's not that I don't ever change my opinion, it's just that I don't easily change an opinion that is based on my personal experience the first time someone steps out from the conventional wisdom with a new idea.


Have you ever listened to a home theater system with and without treatments at the front side first reflection points?


----------



## AndreasMergner

I am in the planning phase of my HT. I have been looking around why/whether there _is such a thing as too low of a RT60_. I understand you want the RT60 balanced as well as you can for all frequencies. It also seems that for music listening, it might be better to have a minimum RT60 to make it sound more "live".


I am planning on running my HT off my PC. There are settings to add reverb/"environmental settings" so that for music listening I could add reverb if music sounds bad. For movies, I could opt to add that or not....but it seems for movies you might want a low RT60, especially for outdoor scenes that would normally have no reverb/echos.


I also took a look at this site where he mentions anechoic being an ideal for a HT. http://www.lenardaudio.com/education/17_cinema_6.html 


Any thoughts or info you could direct me to? TIA!


----------



## mike2060




> Quote:
> Originally Posted by *pepar* /forum/post/18320794
> 
> 
> 
> Have you ever listened to a home theater system with and without treatments at the front side first reflection points?



Yes I have. I have trouble understanding dialogue on some movies with first reflection points treated. But is your opinion of what it sounds like based on what you are told by others? Like if you are told 1st reflections are bad is that going to make you think that whatever you hear without treatment is bad? Maybe you should try without treatment for a couple of weeks and see how you feel based on the knowledge that first reflections may not be bad. Then you will be able to compare without bias.


----------



## mike2060




> Quote:
> Originally Posted by *AndreasMergner* /forum/post/18320805
> 
> 
> I am in the planning phase of my HT. I have been looking around why/whether there _is such a thing as too low of a RT60_. I understand you want the RT60 balanced as well as you can for all frequencies. It also seems that for music listening, it might be better to have a minimum RT60 to make it sound more "live".
> 
> 
> I am planning on running my HT off my PC. There are settings to add reverb/"environmental settings" so that for music listening I could add reverb if music sounds bad. For movies, I could opt to add that or not....but it seems for movies you might want a low RT60, especially for outdoor scenes that would normally have no reverb/echos.
> 
> 
> I also took a look at this site where he mentions anechoic being an ideal for a HT. http://www.lenardaudio.com/education/17_cinema_6.html
> 
> 
> Any thoughts or info you could direct me to? TIA!



This can give you a recommended RT time for your room:

http://www.bobgolds.com/Mode/RoomModes.htm 


The smaller a room is the shorter the RT time is going to be. So a small room is generally going to sound deader than a large room even when furnished and treated.


----------



## AndreasMergner

That's an interesting mode calculator. It isn't very user friendly, but I should be able to figure it out.


I guess my question is not what is the recommended RT60 for my room, but why can't I go less than that? ....especially if I can add reverb for music if I want?


----------



## pepar




> Quote:
> Originally Posted by *mike2060* /forum/post/18320913
> 
> 
> Yes I have. I have trouble understanding dialogue on some movies with first reflection points treated. But is your opinion of what it sounds like based on what you are told by others? Like if you are told 1st reflections are bad is that going to make you think that whatever you hear without treatment is bad? Maybe you should try without treatment for a couple of weeks and see how you feel based on the knowledge that first reflections may not be bad. Then you will be able to compare without bias.










Hey now, the only "bias" I have is my own experience. And being nearly sixty give me a _lot_ of experience.


I asked you if you had done it because I have done it. To my ears, the front sound stage is much more well-defined _with_ those front left and right absorbers. And, perhaps counter-intuitively, the surrounds integrate better with the front soundstage _with_ those absorbers.


Perhaps your room has other problems?


----------



## pepar




> Quote:
> Originally Posted by *AndreasMergner* /forum/post/18321044
> 
> 
> ....especially if I can add reverb for music if I want?



With what would you add "reverb?"


----------



## AndreasMergner




> Quote:
> Originally Posted by *pepar* /forum/post/18321094
> 
> 
> With what would you add "reverb?"



I would be using a HTPC and the sound card allows you to add "ambiance". You can make it sound like a concert hall, a shower, etc. I assume it is adding reverb with different time delays and reflection percents.


Maybe this is not how it usually done (or it is not done). I am not an audio expert/purist so maybe I just don't know better.


----------



## belzarrath

erka and mike2060 Thank you for your response.

I was concerned becuase I remember reading one of the many posts saying to also treat your floor becuase it has a 1st reflection point as well.


Mike, I did know individuals were using felt, however with my possible moisture problem I was wondering if the pads with a moisture barrier will be a acouticval problem.


I wasn't that concerned about it till I went and priced carpet for the room. At $2000 for the room I thinking I should get my best option.


----------



## pepar




> Quote:
> Originally Posted by *AndreasMergner* /forum/post/18321143
> 
> 
> I would be using a HTPC and the sound card allows you to add "ambiance". You can make it sound like a concert hall, a shower, etc. I assume it is adding reverb with different time delays and reflection percents.
> 
> 
> Maybe this is not how it usually done (or it is not done). I am not an audio expert/purist so maybe I just don't know better.



Just a guess here, but I don't think the Acoustical Treatments thread is frequented by people who have recently added reverb electronically to what they were listening.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/18321073
> 
> 
> 
> 
> 
> 
> 
> 
> Hey now, the only "bias" I have is my own experience. And being nearly sixty give me a _lot_ of experience.



Me. too, and I am even older than you are!



> Quote:
> I asked you if you had done it because I have done it. To my ears, the front sound stage is much more well-defined _with_ those front left and right absorbers. And, perhaps counter-intuitively, the surrounds integrate better with the front soundstage _with_ those absorbers.



The problem with anecdotal arguments is that they are not reliably generalizable. My experience with similar experiments confirms your first finding but confutes your second one.


I am not arguing with Ethan's measurements, although they, too, are anecdotal but objective. I have no doubt that there is interference between direct sound and its reflections as he has demonstrated. Heck, that is a large part of what gives a room or a concert hall its unique sound.


What is open for discussion/analysis/experiment is whether those reflections, particularly in a MCH system, are advantageous or not. Our observations conflict. Toole's are based on a much larger sample size but, again, under a single set of controlled circumstances. OTOH, it is only his approach, imho, that can lead to a reliable conclusion if it was to be extended to a more generalizable result. For example, Ethan rightly wonders how the subjects were selected. Toole does offer some info on that but the ears on this forum may not demand the same things as does the general population.


Perhaps we need someone like Sean Olive to re-examine the issue.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18321419
> 
> 
> The problem with anecdotal arguments is that they are not reliably generalizable. My experience with similar experiments confirms your first finding but confutes your second one.
> 
> 
> I am not arguing with Ethan's measurements, although they, too, are anecdotal but objective. I have no doubt that there is interference between direct sound and its reflections as he has demonstrated. Heck, that is a large part of what gives a room or a concert hall its unique sound.
> 
> 
> What is open for discussion/analysis/experiment is whether those reflections, particularly in a MCH system, are advantageous or not. Our observations conflict. Toole's are based on a much larger sample size but, again, under a single set of controlled circumstances. OTOH, it is only his approach, imho, that can lead to a reliable conclusion if it was to be extended to a more generalizable result. For example, Ethan rightly wonders how the subjects were selected. Toole does offer some info on that but the ears on this forum may not demand the same things as does the general population.
> 
> 
> Perhaps we need someone like Sean Olive to re-examine the issue.



Hmmm, I don't think I've ever been "confuted" before ...










Do you make a distinction between spaces where "content" is created and heard (or recorded) and spaces where content is reproduced? And I guess that is only most germane, IMO, for music that was originally performed live. Movie soundtracks and a lot of pop music are creatures of the studio. My experience there is that the best concerts I have ever heard where the band sounded live _exactly_ as they did on the album.


Jeff


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/18321527
> 
> 
> Hmmm, I don't think I've ever been "confuted" before ...



Take that!



> Quote:
> Do you make a distinction between spaces where "content" is created and heard (or recorded) and spaces where content is reproduced? And I guess that is only most germane IMO for music that was originally performed live.
> 
> 
> Jeff



The physics is the same but the goals are different. I hope you will grant that home listening rooms should not be completely dead but, rather, have controlled acoustics different from those of performance spaces. What we are discussing, I think, is not how or why reflections interact but how much (and of what kind) is desirable in a listening room.


I have to admit that I do not have an answer. Consequently, my rooms are _ad hoc_ projects.


----------



## Peter M

I've been confused about this issue since first hearing of Toole's results, as they go against my own experience. Listening with and without first reflection absorption in 5 separate dedicated rooms has left me with absolutely no doubts.


----------



## erkq




> Quote:
> Originally Posted by *Peter M* /forum/post/18321782
> 
> 
> I've been confused about this issue since first hearing of Toole's results, as they go against my own experience. Listening with and without first reflection absorption in 5 separate dedicated rooms has left me with absolutely no doubts.



Wait... I'm interested in your conclusions. You say you've been confused. Then you say you have absolutely no doubts. So what DID your ears tell you in those dedicated rooms?


----------



## yacht422

toole in his writings seems to suggest that is listeners are trained to do so. (visit the harman site and read dr olives musings on the subject)

given that each of us has a different set of ears, listening in a different room, to different non-reverbated sounds, that there is no good single answer. returning to the harman site, search out the pics of their listening room. looks very little like our own h/t i'll wager.(compare harman to mr winers demo room - there is a lot of difference, and the harman room(s) is(are) what dr toole is, in great measure, basing his findings upon)

regarding age, i am 69, and have my hearing checked once a year - i cannot hear above 5khz. this IS a factor when comparing treatments and results, imo!

at any rate i have been unable to discern a difference in my room with the movement of the front treatments. controlling the bass is a related, but different issue.

for me it continues to be a work in progress.

walt


----------



## mike2060

The listeners were widely varied in most of his test. Some had no clue, some were trained, some were audiophiles, etc.


Ethan's graph just shows that reflections cause comb filtering which does not indicate how it will actually sound with our ears considering the sound being high frequencies and having a high Q.


----------



## Peter M

erkq,


Sorry I didn't express that very well










What I should have said is that my own testing has proven to me beyond any doubt that first reflection absorption is a good thing.


I am therefore confused by the Toole test results which contradict my own experience.



One example was at a high end shop listening to B&W 800s with untreated side walls. Something wasn't right so my friend and I grabbed large cushions, sat the shop owner in the sweet spot, and then walked forward along the side walls to the first reflection points. The look on his face was priceless !! This example is very telling to me, as the shop owner thought we were mad and was convinced he had an optimal setup. He was not expecting any improvement.


----------



## erkq




> Quote:
> Originally Posted by *Peter M* /forum/post/18322181
> 
> 
> erkq,
> 
> 
> Sorry I didn't express that very well
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> What I should have said is that my own testing has proven to me beyond any doubt that first reflection absorption is a good thing.
> 
> 
> I am therefore confused by the Toole test results which contradict my own experience.
> 
> 
> 
> One example was at a high end shop listening to B&W 800s with untreated side walls. Something wasn't right so my friend and I grabbed large cushions, sat the shop owner in the sweet spot, and then walked forward along the side walls to the first reflection points. The look on his face was priceless !! This example is very telling to me, as the shop owner thought we were mad and was convinced he had an optimal setup. He was not expecting any improvement.



Yeah... I have no doubt. I'm a big fan of taking the room out of the equation... especially the small rooms we have in our homes.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/18322301
> 
> 
> Yeah... I have no doubt. I'm a big fan of taking the room out of the equation... especially the small rooms we have in our homes.



+1, but nowhere near the point of anechoism. Is that a word?


----------



## AndreasMergner




> Quote:
> Originally Posted by *pepar* /forum/post/18321370
> 
> 
> Just a guess here, but I don't think the Acoustical Treatments thread is frequented by people who have recently added reverb electronically to what they were listening.



Maybe so, but I bet they listened to music that had electronic reverb added in the recording and/or production.


My question was why a low RT60 was bad for HT? Is it just bad for music listening?


Would a low RT60 room sound as "bad" as headphones?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Peter M* /forum/post/18321782
> 
> 
> Listening with and without first reflection absorption in 5 separate dedicated rooms has left me with absolutely no doubts.



Same here, except many dozens of rooms.










If someone has actually tried it both ways in their own room and prefers the sound with no absorption, that's fine with me. At least they actually tried it! But as a general rule, I think it's bad advice to tell others to avoid absorption at reflection points because, well, because it just sounds lousy!











--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *mike2060* /forum/post/18322023
> 
> 
> Ethan's graph just shows that reflections cause comb filtering which does not indicate how it will actually sound with our ears



Graphs can _very much_ predict what something will sound like, at least when one understands the relation between frequencies and perceived sound. If you happen to live anywhere near me in western CT, you're welcome to visit for some fun audio demos and experiments.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18322661
> 
> 
> If you happen to live anywhere near me in western CT, you're welcome to visit for some fun audio demos and experiments.



Don't do it! You'll end up a puppet like the two in the back of the room...










Frank


----------



## pepar




> Quote:
> Originally Posted by *AndreasMergner* /forum/post/18322571
> 
> 
> Maybe so, but I bet they listened to music that had electronic reverb added in the recording and/or production.
> 
> 
> My question was why a low RT60 was bad for HT? Is it just bad for music listening?
> 
> 
> Would a low RT60 room sound as "bad" as headphones?



Well, it would be "electronic" by definition, but it would not have been produced by any electronics that a homeowner is likely to own. But, in any case, that is different. Individual elements are "wet" or "dry" and mixed together. What would be added in the home would be overall and be on top of what is in the recording.


It is very easy to over-dampen a home theater. I am struggling a bit with that myself right now and am looking at swapping some absorption for diffusion.


Jeff


----------



## Dennis Erskine

Kal/Jeff - Toole is older than both of you.










In his research on this, I rather suspect Sean was doing more than sitting in the wings. OTOH, the arm waving is focused on "Toole says this" ignoring that it really should be "Toole says this under the following circumstances".


----------



## Jacob B

This is an interesting read. Albeit confusing
























My VERY slowly HT project has long been planned for 1st reflection treatment with 1" of OC703, including ceiling.


And since there are two rows with four seats, the 1st reflection points are "all over the place", leaving me to plan for treating 4 feet up on side walls from screen wall and 2/3 back into the room.


I guess I will test it when done. I can always remove the OC703 from the frames and leave them empty.


Jacob


----------



## Dennis Erskine

I doubt you'll want them empty (unless your off axis response is bad). You'll likely want diffusion.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18327878
> 
> 
> Kal/Jeff - Toole is older than both of you.



But, together, we are older.



> Quote:
> In his research on this, I rather suspect Sean was doing more than sitting in the wings. OTOH, the arm waving is focused on "Toole says this" ignoring that it really should be "Toole says this under the following circumstances".



Agreed.


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18328228
> 
> 
> I doubt you'll want them empty (unless your off axis response is bad). You'll likely want diffusion.



Diffusion on the first reflection points on the side walls?

And what kind?


I am considering a mix of diffusion and absorption on the REAR wall - diffusion center at ear height, and absorption around that.


But on side walls, I thought I was too close for diffusion.


----------



## Elill




> Quote:
> Originally Posted by *Jacob B* /forum/post/18328565
> 
> 
> I am considering a mix of diffusion and absorption on the REAR wall - diffusion center at ear height, and absorption around that.



Toole recommends the other way around - having absorption in the middle and diffusion on the sides. If there is enough space from seat to the diffuser depending on what type you're going for. Another option is vertical strips of absorption on the rear wall (wider in middle, gap, thinner, gap, thinner etc - talking width of panel not thickness).


Some highly regarding people on the forum seem to use a BAD type panel for treating first reflection points, assuming the speakers have good off axis response (refer discussion a few posts ago). Others also use these types of treatment around your surrounds


----------



## Dennis Erskine

Kal ... OT. You do OK in the resent weather event (I was in Pound Ridge and Mt. Kisco during it .... nasty, nasty.)


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18330569
> 
> 
> Kal ... OT. You do OK in the resent weather event (I was in Pound Ridge and Mt. Kisco during it .... nasty, nasty.)



I resented that weather, too. Had to drive through it Sat night to get from Ridgefield, CT to Manhattan. Three detours due to downed trees or flooded roads. Coming home the next morning was an adventure as well' the Sawmill was closed in at least two places. By the end of the play, every trash bin in Times Square was stuffed with busted umbrellas.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18330569
> 
> 
> Kal ... OT. You do OK in the resent weather event (I was in Pound Ridge and Mt. Kisco during it .... nasty, nasty.)



No problemo! It seems to have hit Westchester hard but all we had was rain and little wind. Our stream was a roiling torrent as a result and the noise was wild and wonderful but that's all. Of course, for all the money spend in the last 2 years on rearranging the drainage on the property, I am happy with that.


Thanks for asking.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/18330710
> 
> 
> I resented that weather, too.



Hahaha... pretty subtle jab at misspelling.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/18330791
> 
> 
> Hahaha... pretty subtle jab at misspelling.



Well, either I thought that's what he meant or it wasn't subtle enough.


----------



## Dennis Erskine

I took the Sawmill on Friday from Pound Ridge to Manalapan (where I had the accident).


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18331170
> 
> 
> I took the Sawmill on Friday from Pound Ridge to Manalapan (where I had the accident).



Ouch.


----------



## eiger

Guys,


Need your help. I'm looking at adding some panels on the front screen wall behind my L and R.


Given that I'm not really in a position to treat my entire front screen wall or build a false wall at this point.


Is there a happy medium that would ALSO allow me to put something behind my 110" 16:9 screen to help in the process?


What would you reccomend in terms of thin material behind a fixed screen? I have a Carada 110" BW. (A Non AT Screen)


Wasn't sure if there was a best practice here or if such a thing existed, or if it would even be beneficial. Screen wall is single Drywall against foundation.


Thanks!


----------



## Weasel9992

I'm a little confused I think, but I'd just add a 2" or 4" panel behind each speaker (assuming that you've treated the corners already). If that's all you have room for then it'll have to do. Am I missing something?


Frank


----------



## design1stcode2nd

Breaking in with hopefully a simple question, I read through a few pages but most of this is over my head. For those who are creating a HT from scratch I can see how you are able to put the different kinds of material in the walls. However, I'm going to be converting a portion of a finished basement into a HT so the exterior walls already have regular insulation and drywall which I won't be messing with.


I've attached a quickie floor plan of what I have and or plan to do. I'll be able to put sound absorption material behind the screen and speakers and in the new wall that will be built. On the remaining walls I was planning on adding acoustic panels (and from my reading of this thread I should use cotton batting) above a 36 chair rail.


Is that going to work? I don't plan on covering the walls in fabric panels just a chair rail with decorative panels below with paint above.


----------



## SierraMikeBravo

^^^^


For the most part, not the most prudent thing to do. May I suggest taking a look through this thread some more, or if timing is essential, or things continue to remain confusing, consider hiring an acoustical consultant to layout the room and treatment strategy for you. Best wishes!


----------



## mangala8




> Quote:
> Originally Posted by *mike2060* /forum/post/18320011
> 
> 
> Floyd Toole recommends clipped-pile carpet with 40oz/sq yd felt underlay.



I'm converting a living room that has hardwood flooring, and I don't want to damage it by installing wall-to-wall carpet. So I think I am stuck with some kind of carpet tiles.


Does anyone have an opinion about whether the thickness of the carpet tiles matters? Or is it mostly the underlayment that provides acoustic benefits in a traditional carpet setup?


Thinner carpet tiles are cheaper, so that is my preference all else being equal. And I would be willing to add a throw rug at the first reflection point if that would take care of any thin tile downsides.


Thanks for any advice!


----------



## pepar




> Quote:
> Originally Posted by *mangala8* /forum/post/18340466
> 
> 
> I'm converting a living room that has hardwood flooring, and I don't want to damage it by installing wall-to-wall carpet. So I think I am stuck with some kind of carpet tiles.
> 
> 
> Does anyone have an opinion about whether the thickness of the carpet tiles matters? Or is it mostly the underlayment that provides acoustic benefits in a traditional carpet setup?
> 
> 
> Thinner carpet tiles are cheaper, so that is my preference all else being equal. And I would be willing to add a throw rug at the first reflection point if that would take care of any thin tile downsides.
> 
> 
> Thanks for any advice!



I used a throw rug with heaviest padding I could find underneath.


----------



## nathan_h




> Quote:
> Originally Posted by *design1stcode2nd* /forum/post/18335775
> 
> 
> Breaking in with hopefully a simple question, I read through a few pages but most of this is over my head. For those who are creating a HT from scratch I can see how you are able to put the different kinds of material in the walls. However, I'm going to be converting a portion of a finished basement into a HT so the exterior walls already have regular insulation and drywall which I won't be messing with.
> 
> 
> I've attached a quickie floor plan of what I have and or plan to do. I'll be able to put sound absorption material behind the screen and speakers and in the new wall that will be built. On the remaining walls I was planning on adding acoustic panels (and from my reading of this thread I should use cotton batting) above a 36 chair rail.
> 
> 
> Is that going to work? I don't plan on covering the walls in fabric panels just a chair rail with decorative panels below with paint above.



Although we go back and forth about treating first reflection points with absorption, treating a bunch of non first reflection points (ie, below the chair rail) is probably a deprecated approach for most situations.


What the heck am I talking about? Here are some good short explanations of a good starting point:

http://www.realtraps.com/rfz.htm 

http://www.gikacoustics.com/news_020209.html


----------



## belzarrath

Well I am not confused, maybe i don't understand "deprecated" (obsolescent and in the process of being phased out)

I was under the impression, from the start of this thread through the majority. That a person is in general suppose to use from floor up to 44" 1" Insul-Shield and from there to ceiling nothing or batting if doing a full cloth wall. Front wall was entirely 1" Insul-Shield.

What is the good practice for room acoustic in a home theater? If its not what is stated in the beginning of the thread maybe that should be revised.

I'm about to begin my wall covering and acoustics. Do I need a new plan?

All the talk of first reflection points is very interesting but, like wise I need a concrete direction to go.


----------



## nathan_h

The person who posted at the start of this thread did so about 7 years ago, and hasn't been back to this thread in almost that much time (as a poster).


Those two links in my post are the best practices out there. Some people argue for even less absorption.


But almost no one calls for thin (1") in all the places your are talking about.


From personal experience and based on data here and elsewhere, you want thicker panels (say 3 or 4 or 5 inches), and less wall coverage.


----


Two things you want to pay attention to for the best sound (in terms of room treatments):


1. Bass trapping

2. Absorption of first reflection points (though in larger rooms, diffusion can work instead of, or in tandem with, absorption).


----------



## whumpf

Well, I am confused. In post #5 of this thread the poster asks: "1) Is 1" Insul-Shield (or equivalent) adequate for the front wall, or should it be increased to 2" if possible?"


In post #6 Dennis Erskine answers "I would not use the 2" material...it will very likely be too absorptive."


Has this advice changed since the thread started?


----------



## belzarrath




> Quote:
> Originally Posted by *whumpf* /forum/post/18361656
> 
> 
> Well, I am confused. In post #5 of this thread the poster asks: "1) Is 1" Insul-Shield (or equivalent) adequate for the front wall, or should it be increased to 2" if possible?"
> 
> 
> In post #6 Dennis Erskine answers "I would not use the 2" material...it will very likely be too absorptive."
> 
> 
> Has this advice changed since the thread started?



Whumf trust me your not the only one. I thought I had everything planned and figured. Now I'm lost and about to say screw it. you would think after reading and researching for nearly 1 year I 'd have a clue.


I'm not sure why the moderator hasn't change or updated the beginning and posted recomended procedure to acoustically treat your room.

I believe it would decrease their amount of repeated inquaries on topics, I'm sure they are tired of answering, if they would post a procedure to acoustically treat your room.


Yes I know everyroom is different but maybe there is a common practice.


1) Measure RT60

a) What to do with this?

2) Find 1st reflection points ( all surfaces )

a) Method - mirrior.

b) Treatment of 1st reflection points - Clueless

3) Building absorbtion panels and total wall treatment.

a) Materials - list of exceptible material

b) Absorbtion material - OC703, Insul-Shield ect, and thickness

4) Bass traps

a)

5)ect.


Just an Idea, and no this isn't correct. I'm throwing out a starting point and I'm sure theres lots of things that could be included.


----------



## pepar

whumpf and belzarreth, those are all good questions and the information is all "out there." You can probably get a question or two at a time answered here, but no one on a forum thread can start you at the basics and bring you the whole way through all the variables and have you be able to design a theater at the end.


As for changing information, the *thinking* on how to treat rooms has changed over the years. When I research a new topic, I always make sure that the content is relatively recent. And there seems to be different schools of thought on some things.


Jeff


----------



## belzarrath

Well I thought this would be the thread for these questions and information, if not could you lead me to them. I do not mind reading and learning; which i've tried for the last year, however, going through 200 pages of posts which goes all directions is very miss leading and unfortunitly dishearting.

I have asked questions here and other forums which has lead me to the general practice of what was first listed.

If a person follows the listed procedure is it detrimental to the acoustics of the room, better than a cement basement?


----------



## nathan_h

There is a reason the experts get paid a few thousand dollars (and up) to design good acoustic spaces for home theater: It's complicated and a specialized skill set.


However, there are some basics that you can follow, and get good results -- without hiring an expert. The links I provided will NOT steer your wrong, and are an improvement over what you describe as your plan.


If you prefer a video, try this. A 15 minute investment and you'll be miles ahead of most people when it comes to understanding and implementing good home theater acoustic treatment.

http://www.realtraps.com/video_setup.htm 


--------


If you want to get some written details about the variations of the best practices, here are some great links to check out:

http://www.audioholics.com/education...cs-principles/


----------



## mangala8

I agree with nathan_h's suggestion...those links are a good place to start. I've been trying to learn about this subject too and found some of those articles very helpful.


Another resource...I also just started reading the Floyd Toole book that has been discussed here. I skipped ahead to the practical recommendations and have found them very clearly explained so far.


----------



## pepar




> Quote:
> Originally Posted by *belzarrath* /forum/post/18363002
> 
> 
> Well I thought this would be the thread for these questions and information, if not could you lead me to them. I do not mind reading and learning; which i've tried for the last year, however, going through 200 pages of posts which goes all directions is very miss leading and unfortunitly dishearting.
> 
> I have asked questions here and other forums which has lead me to the general practice of what was first listed.
> 
> If a person follows the listed procedure is it detrimental to the acoustics of the room, better than a cement basement?


 'Nother one for you ....


----------



## mangala8




> Quote:
> Originally Posted by *pepar* /forum/post/18340648
> 
> 
> I used a throw rug with heaviest padding I could find underneath.



Thanks pepar. So from your pictures it looks like you left the rest of the room as hardwood?


Then I should be fine with a similar approach. I'll probably still cover the whole room with the thin carpet tiles (for light control), then do a throw rug and pad in between the screen and the front row.


----------



## pepar




> Quote:
> Originally Posted by *mangala8* /forum/post/18364604
> 
> 
> Thanks pepar. So from your pictures it looks like you left the rest of the room as hardwood?
> 
> 
> Then I should be fine with a similar approach. I'll probably still cover the whole room with the thin carpet tiles (for light control), then do a throw rug and pad in between the screen and the front row.



The floor is wood, but not really much of it is exposed due to the carpeted riser. BTW, the next "chapter" is as of now un-written, but the rug was removed and I am looking at replacing some absorption with diffusion.


----------



## highlife

Hello, working on treating my theater room and I want to make sure I am doing the right things. Some of you have already provided great advice, thanks. I am treating behind my screen wall, attempting to reduce noise transmitting to the living room above, and absorb sound for the best sound reproduction from behind the screen into the main room. I have installed safe and sound insulation to reduce noise carrying upward, and it has worked well, see pics attached.


Next question I Have, what should I do, if anything, to the concrete block wall behind the screen? I was thinking a linacoustic RC type product, do I need it?


----------



## belzarrath

Thank you for your help, obviously I will be doing more reading. I not sure what my new direction will be but I'm sure it will envolve taking measurements and much more time.


----------



## gravi

Count me in among the confused. I have also done much reading and based a lot of my treatments on the first 50 to 100 pages of this thread. Obviously, as the thread goes on differing opinions start to emerge, which sometimes contradict each other. I personally took what I thought was a consensus approach to start with - couple of 1" OC703 panels on side walls, behind L/R speakers, and bass traps in the corners. I went with the 1" panels because they look better and the original purpose was to treat high-frequency reflections. Some people reccommend 2" or even 4" (wouldn't that be a bass trap?), on the walls which would look ridiculuous if you are not building from scratch and using panels.


Anyway, so far I like the results and will wait and see before doing any further work.


----------



## pepar




> Quote:
> Originally Posted by *gravi* /forum/post/18368776
> 
> 
> Count me in among the confused. I have also done much reading and based a lot of my treatments on the first 50 to 100 pages of this thread. Obviously, as the thread goes on differing opinions start to emerge, which sometimes contradict each other. I personally took what I thought was a consensus approach to start with - couple of 1" OC703 panels on side walls, behind L/R speakers, and bass traps in the corners. I went with the 1" panels because they look better and the original purpose was to treat high-frequency reflections. Some people reccommend 2" or even 4" (wouldn't that be a bass trap?), on the walls which would look ridiculuous if you are not building from scratch and using panels.
> 
> 
> Anyway, so far I like the results and will wait and see before doing any further work.



Thicker absorbers reach lower frequency-wise. The sound hitting the first reflection points is full range, so the absorber should be as full range as possible. Beyond the first reflections, the concern is that absorbing the highs/mid-highs and not the mids/mid lows will result in a dead, boomy room. (Bass traps are needed for the lows/low lows.) Once you put "looking better" above "working better", you have gone off track, IMO.


Four inch panels might be an odd thing to see and could even encroach into the room space, if not physically then certainly visually. But the benefit of bumping the 1" to 2" seems to me to outweigh the additional 1" of thickness.


Just my $.02.


Jeff


----------



## Jacob B

Count me among the confused as well.

I based my plan (not done yet) on the first 150 pages as well, when concensus seemed to be something like:

- 1st reflection treatment with absorbtion (1" OC703) from floor and up to 4' - from screen and two thirds back into room.

- 2" OC703 on whole front wall behind false screen wall

- Bass traps in corners - as many corners as possible.

- As this is an attic room, I have sloping walls, starting from 5' up the side walls. Therefore, I will treat the sloping walls as well with 2" OC703 in 3.5" deep frames, each panel measuring 40" x 6" on the inside. They will be mounted as vertical strips, with 8" of air between each panel. The will give 1st reflection absorption and crude difussion.

- I also consider 2-3 QRD Diffusor (from Real Traps) for the center back wall - with 6" absorption (OC703) as fallback - the QRDs are expensive...


The whole discussion about using a mirror etc to find first reflections seems to me to be for HT with two seats or something like that - for a dedicated HT room with multiple seats and two rows or more, the first reflection points are going to be all over the place.









I have two rows of four seats, second row on a riser.

1st reflections from the three identical front speakers pretty much include most of the sidewall as described above in plan...










Now, my room is small - 13.4' x 20' x 8'. It's my understanding (based on this thread, Real Traps and GIK homepages etc) that diffusion works best in larger rooms (or rather, when the listener is far away from the diffusor).


When Dennis Erskine now mentions diffusion for 1st reflection points, instead of absorption - does that go for a small room like mine as well?










And what kind of diffusion products for this specific task?










Cheers from Denmark,









Jacob


----------



## Weasel9992




> Quote:
> Originally Posted by *belzarrath* /forum/post/18362599
> 
> 
> 1) Measure RT60
> 
> a) What to do with this?
> 
> 2) Find 1st reflection points ( all surfaces )
> 
> a) Method - mirrior.
> 
> b) Treatment of 1st reflection points - Clueless
> 
> 3) Building absorbtion panels and total wall treatment.
> 
> a) Materials - list of exceptible material
> 
> b) Absorbtion material - OC703, Insul-Shield ect, and thickness
> 
> 4) Bass traps
> 
> a)
> 
> 5)ect.
> 
> 
> Just an Idea, and no this isn't correct. I'm throwing out a starting point and I'm sure theres lots of things that could be included.



I'd make #4 your #1. An RT60 of a small room is not very useful...if you really want to know what things look like across the broad bandwidth at a particular place in the room, then shooting with room EQ Wizard, Fuzzmeasure or whatever, will tell you that and also allow you to generate a waterfall measurement so you can see what your ringing times look like. If you want to go a step further you can use an Energy Time Envelope (ETC) that'll tell you in fairly precise way where your problems are in terms of frequency and position.


Frank


----------



## pepar

If "what to do with waterfall" pops into your mind







, the idea is to get everything to "ring down" at the same time. Anything that rings way beyond the average is a problem.


----------



## Jacob B




> Quote:
> Originally Posted by *pepar* /forum/post/18368863
> 
> 
> Thicker absorbers reach lower frequency-wise. The sound hitting the first reflection points is full range, so the absorber should be as full range as possible. Beyond the first reflections, the concern is that absorbing the highs/mid-highs and not the mids/mid lows will result in a dead, boomy room. (Bass traps are needed for the lows/low lows.) Once you put "looking better" above "working better", you have gone off track, IMO.
> 
> 
> Four inch panels might be an odd thing to see and could even encroach into the room space, if not physically then certainly visually. But the benefit of bumping the 1" to 2" seems to me to outweigh the additional 1" of thickness.
> 
> 
> Just my $.02.
> 
> 
> Jeff



It was my understanding that ringing was a bigger problem than low freq 1st reflections









Therefore, I plan to have a 4" panel to the sides of the 1st row (primary), and 1" panels between that and the screen wall. The two sidewall surround speakers (MK-SS150 tripoles) will be mounted above this 4" panel (=90 degrees to 1st row).


I also plan for a 4" OC703 panel in ceiling right above 1st row, to counter ringing as well.


----------



## Dennis Erskine




> Quote:
> When Dennis Erskine now mentions diffusion for 1st reflection points, instead of absorption - does that go for a small room like mine as well?



I believe he'd said it does apply; however, I believe he'd also say that depends on the quality of the off axis response of your speakers.


----------



## Jacob B




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18369241
> 
> 
> I believe he'd said it does apply; however, I believe he'd also say that depends on the quality of the off axis response of your speakers.



My speakers are known for good off axis response - its a key concept for the company - but whether this measures up, I don't know








I think part of the concept is the rear radiation ports, which I guess I nullify with the front wall treatment anyway










So where does that leave me?


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Jacob B* /forum/post/18369430
> 
> 
> My speakers are known for good off axis response - its a key concept for the company - but whether this measures up, I don't know
> 
> 
> 
> 
> 
> 
> 
> I think part of the concept is the rear radiation ports, which I guess I nullify with the front wall treatment anyway
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> So where does that leave me?



Hi Jacob,


How do you know this? I am sure Dennis "he'd also say" would also say (







)...never, ever believe what the manufacturer has told you. It may or may not be true for your particular speakers. You need to test your individual speakers to make sure their off-axis is response is good. Best wishes!


----------



## Jacob B




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18369806
> 
> 
> Hi Jacob,
> 
> 
> How do you know this? I am sure Dennis "he'd also say" would also say (
> 
> 
> 
> 
> 
> 
> 
> )...never, ever believe what the manufacturer has told you. It may or may not be true for your particular speakers. You need to test your individual speakers to make sure their off-axis is response is good. Best wishes!



How do I measure this (my self) and what does the result mean, i.e.

good off axis response => x treatment of 1st reflection points?

bad off axis response => y treatment of 1st reflection points?


thanks










Jacob


----------



## giomania




> Quote:
> Originally Posted by *gravi* /forum/post/18368776
> 
> 
> Count me in among the confused. I have also done much reading and based a lot of my treatments on the first 50 to 100 pages of this thread. Obviously, as the thread goes on differing opinions start to emerge, which sometimes contradict each other. I personally took what I thought was a consensus approach to start with - couple of 1" OC703 panels on side walls, behind L/R speakers, and bass traps in the corners. I went with the 1" panels because they look better and the original purpose was to treat high-frequency reflections. Some people reccommend 2" or even 4" (wouldn't that be a bass trap?), on the walls which would look ridiculuous if you are not building from scratch and using panels.
> 
> 
> Anyway, so far I like the results and will wait and see before doing any further work.





> Quote:
> Originally Posted by *Jacob B* /forum/post/18368976
> 
> 
> Count me among the confused as well.
> 
> I based my plan (not done yet) on the first 150 pages as well, when concensus seemed to be something like:
> 
> - 1st reflection treatment with absorbtion (1" OC703) from floor and up to 4' - from screen and two thirds back into room.
> 
> - 2" OC703 on whole front wall behind false screen wall
> 
> - Bass traps in corners - as many corners as possible.
> 
> - As this is an attic room, I have sloping walls, starting from 5' up the side walls. Therefore, I will treat the sloping walls as well with 2" OC703 in 3.5" deep frames, each panel measuring 40" x 6" on the inside. They will be mounted as vertical strips, with 8" of air between each panel. The will give 1st reflection absorption and crude difussion.
> 
> - I also consider 2-3 QRD Diffusor (from Real Traps) for the center back wall - with 6" absorption (OC703) as fallback - the QRDs are expensive...
> 
> 
> The whole discussion about using a mirror etc to find first reflections seems to me to be for HT with two seats or something like that - for a dedicated HT room with multiple seats and two rows or more, the first reflection points are going to be all over the place.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have two rows of four seats, second row on a riser.
> 
> 1st reflections from the three identical front speakers pretty much include most of the sidewall as described above in plan...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Now, my room is small - 13.4' x 20' x 8'. It's my understanding (based on this thread, Real Traps and GIK homepages etc) that diffusion works best in larger rooms (or rather, when the listener is far away from the diffusor).
> 
> 
> When Dennis Erskine now mentions diffusion for 1st reflection points, instead of absorption - does that go for a small room like mine as well?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And what kind of diffusion products for this specific task?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Cheers from Denmark,
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jacob



When I read this thread last year from the beginning, I printed it all off and read it during my commute; don't worry, I take a commuter train (2 hours a day)!. For some reason, I cannot absorb technical details and complex information while reading on the computer. Perhaps that is becuase whenever I am at a computer, I am frequently interrupted.


Anyway, this allowed me to fully concentrate on the subject matter and highlight & save the good parts. I started to figure out who was knowledgeable and realized there were differing opinions. I simply collected the relevant posts on various subjects so I could see all opinions when it came time to make my design/purchase decisions for acoustic treatments.


I employed this same technique when I initially read through the Audyssey thread, and then subsequently created the setup guide for my own edification / sanity. When folks asked where I got the information from, I could pull up the relevant post.


To make a long story short, it is difficult in long threads (spanning years) to assimilate the information by simply searching or reading on the computer. Unless, of course, one has a photographic memory. To complicate matters, then Dr. Toole comes out with a new book, and we find ourselves some elements of design / treatment. This is the nature of our hobby, I guess.


Mark


----------



## Speedskater

And then we have to remember that some of the articles we read are about 2 channel music rooms and some are about 5.1 or 7.1 home theater rooms.

In general home theater rooms are much more absorbent. As 2 channel needs the reflections to help with the stereo illusion.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Speedskater* /forum/post/18370707
> 
> 
> And then we have to remember that some of the articles we read are about 2 channel music rooms and some are about 5.1 or 7.1 home theater rooms.
> 
> In general home theater rooms are much more absorbent. As 2 channel needs the reflections to help with the stereo illusion.



Ahh, but what is a home theater setup if not an enhancement upon two channels for multiple listeners? Food for thought. Best wishes!


----------



## nathan_h




> Quote:
> Originally Posted by *Jacob B* /forum/post/18368976
> 
> 
> Count me among the confused as well.
> 
> I based my plan (not done yet) on the first 150 pages as well, when concensus seemed to be something like:
> 
> - 1st reflection treatment with absorbtion (1" OC703) from floor and up to 4' - from screen and two thirds back into room.
> 
> - 2" OC703 on whole front wall behind false screen wall
> 
> - Bass traps in corners - as many corners as possible.
> 
> - As this is an attic room, I have sloping walls, starting from 5' up the side walls. Therefore, I will treat the sloping walls as well with 2" OC703 in 3.5" deep frames, each panel measuring 40" x 6" on the inside. They will be mounted as vertical strips, with 8" of air between each panel. The will give 1st reflection absorption and crude difussion.
> 
> - I also consider 2-3 QRD Diffusor (from Real Traps) for the center back wall - with 6" absorption (OC703) as fallback - the QRDs are expensive...
> 
> 
> The whole discussion about using a mirror etc to find first reflections seems to me to be for HT with two seats or something like that - for a dedicated HT room with multiple seats and two rows or more, the first reflection points are going to be all over the place.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have two rows of four seats, second row on a riser.
> 
> 1st reflections from the three identical front speakers pretty much include most of the sidewall as described above in plan...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Now, my room is small - 13.4' x 20' x 8'. It's my understanding (based on this thread, Real Traps and GIK homepages etc) that diffusion works best in larger rooms (or rather, when the listener is far away from the diffusor).
> 
> 
> When Dennis Erskine now mentions diffusion for 1st reflection points, instead of absorption - does that go for a small room like mine as well?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And what kind of diffusion products for this specific task?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Cheers from Denmark,
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jacob



My room is similar to yours (17'x12.5'x7.5' -- nice of you to translate into feet rather than use metrics...) but even a little smaller.


I have two rows of seats: one couch for each. The second row couch is on a riser.


Using the mirror method I was able to cover the side wall first reflection points for all three front speakers for almost all sitting positions with just two 2'x'4 panels on each of the side walls.


That, plus bass trapping in every corner and under the screen (ie, where the screen wall meets the floor), please two more panels on the back wall, and heavy carpet on the floor, have really made things solid and clear. Yet most of the wall space is still uncovered.


----------



## belzarrath

I'm glad to see others were having the same difficulties.









Wouldn't it be relevant for those individuals with lots of experience to each make a proposed summary of a method to acoustically treat a HT.

Even if they were opposing views. Individuals could choose which they feel best fits their needs and ask questions in this forum based on those summaries.




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18368990
> 
> 
> I'd make #4 your #1. An RT60 of a small room is not very useful...if you really want to know what things look like across the broad bandwidth at a particular place in the room, then shooting with room EQ Wizard, Fuzzmeasure or whatever, will tell you that and also allow you to generate a waterfall measurement so you can see what your ringing times look like. If you want to go a step further you can use an Energy Time Envelope (ETC) that'll tell you in fairly precise way where your problems are in terms of frequency and position.
> 
> 
> Frank



Weasel9992 thank you for your response to my list, I quickly wrote that up with out much thought.

I was just trying to give ideas to enhance the thread. I spend time also on the diy screen thread which employs this method.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Speedskater* /forum/post/18370707
> 
> 
> 2 channel needs the reflections to help with the stereo illusion.



To my ears, avoiding small-room reflections _improves_ stereo imaging, and also makes the music sound larger and wider. When you allow reflections in a typical domestic size room, those reflections drown out the "larger room" reverb that's present in many recordings. So the net result from reflections in a small room is a smaller sound.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18375951
> 
> 
> To my ears, avoiding small-room reflections _improves_ stereo imaging, and also makes the music sound larger and wider. When you allow reflections in a typical domestic size room, those reflections drown out the "larger room" reverb that's present in many recordings. So the net result from reflections in a small room is a smaller sound.
> 
> 
> --Ethan



Big +1 from me.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18375951
> 
> 
> To my ears, avoiding small-room reflections _improves_ stereo imaging, and also makes the music sound larger and wider. When you allow reflections in a typical domestic size room, those reflections drown out the "larger room" reverb that's present in many recordings. So the net result from reflections in a small room is a smaller sound.
> 
> 
> --Ethan





> Quote:
> Originally Posted by *Weasel9992* /forum/post/18377843
> 
> 
> Big +1 from me.
> 
> 
> Frank



How do you reconcile your experience wrt this with Dr Toole's recent work?


I must admit to being confused by this ...


Jeff


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/18377874
> 
> 
> How do you reconcile your experience wrt this with Dr Toole's recent work?



I cannot speak for the others, but for me: I have tried it both ways in several rooms (good rooms, bad rooms, and everything in between), and it typically sounds better (clearer stereo image and soundstage details, I hear more of a small room when the recording is creating a small room sound and more of a large room when the recording is creating a large room sound) to me when treating first reflection points, especially lateral ones, with thick absorption. Some rooms and some speakers benefit more from this.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/18377874
> 
> 
> How do you reconcile your experience wrt this with Dr Toole's recent work?
> 
> 
> I must admit to being confused by this ...
> 
> 
> Jeff



I'll admit in turn that it's not necessarily an objective statement on my part...more of a subjective observation. It's not my intention to contradict Toole...I'm not that arrogant yet.










Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18378169
> 
> 
> I'll admit in turn that it's not necessarily an objective statement on my part...more of a subjective observation. It's not my intention to contradict Toole...I'm not that arrogant yet.



I've read his paper - at least the part that is in English - and I am still not sure that his work was done with/applies to a residential-sized room with a multichannel system. I, rightly or wrongly, thought it was for 2-channel systems ... reproducing "symphonic" music.


Jeff


----------



## Speedskater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18375951
> 
> 
> To my ears, avoiding small-room reflections _improves_ stereo imaging, and also makes the music sound larger and wider. When you allow reflections in a typical domestic size room, those reflections drown out the "larger room" reverb that's present in many recordings. So the net result from reflections in a small room is a smaller sound.
> 
> --Ethan



For 2 channel stereo music Siegfried Linkwitz prefers a more reflective room.

http://www.linkwitzlab.com/stereo%20reproduction.htm


----------



## Kal Rubinson

Sure. Stereo relies on room reflections for any sense of envelopment. MCH provides that from the surround channels.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/18377874
> 
> 
> How do you reconcile your experience wrt this with Dr Toole's recent work?



I wouldn't even try.










Seriously, all I can go by is my ears and my own experience. And of course hard measurements showing a much flatter response with all early reflections absorbed.


--Ethan


----------



## glaufman

One possible way to reconcile that is even Toole's recent work, as quoted here a few moons ago, I haven't read it myself, said that for critical listening, killing early reflections aided imaging, but casual listeners in a casual setting preferred having the envelopment of the early reflections... so it seems to me this would come down to reference vs preference...


----------



## Weasel9992




> Quote:
> Originally Posted by *glaufman* /forum/post/18385303
> 
> 
> One possible way to reconcile that is even Toole's recent work, as quoted here a few moons ago, I haven't read it myself, said that for critical listening, killing early reflections aided imaging, but casual listeners in a casual setting preferred having the envelopment of the early reflections... so it seems to me this would come down to reference vs preference...



Interesting post Greg. That sounds very reasonable.


Frank


----------



## Kal Rubinson




> Quote:
> Originally Posted by *glaufman* /forum/post/18385303
> 
> 
> One possible way to reconcile that is even Toole's recent work, as quoted here a few moons ago, I haven't read it myself, said that for critical listening, killing early reflections aided imaging, but casual listeners in a casual setting preferred having the envelopment of the early reflections... so it seems to me this would come down to reference vs preference...



I see this as preference vs. preference since the sense of envelopment is a component of the original event.


----------



## pepar




> Quote:
> Originally Posted by *glaufman* /forum/post/18385303
> 
> 
> One possible way to reconcile that is even Toole's recent work, as quoted here a few moons ago, I haven't read it myself, said that for critical listening, killing early reflections aided imaging, but casual listeners in a casual setting preferred having the envelopment of the early reflections... so it seems to me this would come down to reference vs preference...



Greg, I think the context here _is_ critical listening. When I am in a casual setting, I prefer a margarita and could give a **** about acoustics.










Jeff


----------



## glaufman




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18385360
> 
> 
> Interesting post Greg. That sounds very reasonable.



Thanks. It's a shame, though, that I just made it up and don't have the foggiest clue what I'm talking about.










> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18385422
> 
> 
> I see this as preference vs. preference since the sense of envelopment is a component of the original event.



Wouldn't that depend on the recording in question? And therefore the intent of the artist? More to the point, I think, is that accurate imaging is not necessarily the same thing as envelopment.


> Quote:
> Originally Posted by *pepar* /forum/post/18385479
> 
> 
> Greg, I think the context here _is_ critical listening. When I am in a casual setting, I prefer a margarita and could give a **** about acoustics.



Understood, but I think you mean that you "couldn't" give a...


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *glaufman* /forum/post/18385805
> 
> 
> More to the point, I think, is that accurate imaging is not necessarily the same thing as envelopment.



Hi Greg,


I am not 100% sure what you are referring to, but I think you may be referring to focus rather than imaging. IMHO, imaging can be defined as both focus and/or envelopment, and the combination of the two contribute to recreating a believable soundstage in three dimensional space if properly employed. Best wishes!


----------



## glaufman

That's probably fair ... I may not be doing a very good job of articulating what I mean here, but haven't we all heard systems (which of course include the room and it's reflections) that sound as if the sound is all around you, but in a random, as opposed to your focussed, way?


The first time I head such a thing I was rather impressed. Now I much prefer listening to a system that produces focussed imaging, as you say. But I could see the uninitiated, as I once was, who may still be unaware that such a thing is possible, being preferring random envelopment to a system that just sounds two dimensional. We're all aware of the success of a company that claims to have invented that sort of random envelopment...


----------



## pepar

Those speakers are _great_ for casual listening!!!


----------



## glaufman











I'm so ashamed I have a friend who works there.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18385422
> 
> 
> I see this as preference vs. preference since the sense of envelopment is a component of the original event.





> Quote:
> Originally Posted by *glaufman* /forum/post/18385805
> 
> 
> Wouldn't that depend on the recording in question? And therefore the intent of the artist?



Perhaps but my focus and concern is always about the accurate reproduction of a real event (and mostly classical music). If the program content was studio-created, your distinctions might be relevant.



> Quote:
> More to the point, I think, is that accurate imaging is not necessarily the same thing as envelopment.





> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/0
> 
> 
> I am not 100% sure what you are referring to, but I think you may be referring to focus rather than imaging. IMHO, imaging can be defined as both focus and/or envelopment, and the combination of the two contribute to recreating a believable soundstage in three dimensional space if properly employed.



Amen.


----------



## Dennis Erskine




> Quote:
> I am not 100% sure what you are referring to, but I think you may be referring to focus rather than imaging. IMHO, imaging can be defined as both focus and/or envelopment, and the combination of the two contribute to recreating a believable soundstage in three dimensional space if properly employed.



You listened well in class, Grasshopper. Now, more wax on, wax off.


----------



## SierraMikeBravo

ahhh...sank you Master!


----------



## glaufman




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18387822
> 
> 
> Perhaps but my focus and concern is always about the accurate reproduction of a real event (and mostly classical music). If the program content was studio-created, your distinctions might be relevant.



That's fair enough. Perhaps the distinction I'm making is more between the believable and, um, other...


----------



## sb1

A little input would be appreciated. I searched, but didn't quite get what I needed.


I work in a manufacturing facility that produces polyurethane foam. We simply make the foam, then ship it to customers who fabricate it to their needs. We produce everything from low density foams (more open cell structure) to high density ones (more closed).


I have virtually unlimited access to these, and can have my guys cut them to whatever size I wish. My question is, would any of this be effective in a cheap DIY solution to acoustic paneling? I can also have them covered with whatever material would work. I'm aware that I can experiment with it, but would really rather know if it would be worth the trouble. Thanks.


----------



## nathan_h

Yes, in fact, one of the big names in acoustic panels (Auralex) uses foam almost exclusively, and it works.


It is not as effective as fiberglass -- meaning thicker panels are needed for the same impact.


I cannot tell you whether low density or high density is better (though there is a difference in the acoustic properties).

*And you want to make very sure that the foam you get is fire-retardant because a lot of industrial foams, like packing materials, are very flammable and therefor dangerous to hang on your walls/ceiling.*


----------



## sb1

Thanks for the response, Nathan. That gives me some hope in using it.


Yes, I'm all too familiar with fire retardant foam. It's one of our big concerns and several of our grades can't get used if they fail the tests.


----------



## bodhisafa

I have both roxul and oc 703, if I use burlap material to cover the panels, do I have to wrap them with cotton batting before I wrap them with burlap?


Trying to keep the fiberglass fibers within the panels? Any suggestions.


----------



## Weasel9992




> Quote:
> Originally Posted by *bodhisafa* /forum/post/18394892
> 
> 
> I have both roxul and oc 703, if I use burlap material to cover the panels, do I have to wrap them with cotton batting before I wrap them with burlap?
> 
> 
> Trying to keep the fiberglass fibers within the panels? Any suggestions.



No, you don't. If it'll make you feel better you can, but it's really not necessary.


Frank


----------



## kevinzoe




> Quote:
> Originally Posted by *sb1* /forum/post/18394043
> 
> 
> A little input would be appreciated. I searched, but didn't quite get what I needed.
> 
> 
> I work in a manufacturing facility that produces polyurethane foam. We simply make the foam, then ship it to customers who fabricate it to their needs. We produce everything from low density foams (more open cell structure) to high density ones (more closed).
> 
> 
> I have virtually unlimited access to these, and can have my guys cut them to whatever size I wish. My question is, would any of this be effective in a cheap DIY solution to acoustic paneling? I can also have them covered with whatever material would work. I'm aware that I can experiment with it, but would really rather know if it would be worth the trouble. Thanks.



sb1 - take a look at this RPG link to their Skyline diffuser which looks to me like it might be made out of high density polyurethane foam:

http://www.rpginc.com/products/skyline/index.htm 


Does this look like the same stuff you have access to? If so then you may wish to build a Skyline diffuser but would need something to cut the varying depth cells with . . . If you're interested then PM me and I can send you the best calculator I found and a write up on how to do it . . .


----------



## pepar

This is probably wacky, but I figure if anybody would know, it would be somebody subscribed to this thread. I need to mount a speaker in a location that has no 2x4 wall studs (there's a pocket door) and am considering mounting it on a pipe flanged between the ceiling and the floor. Besides making the pipe strong enough to hold the speaker, would there be any bad vibrations of the pipe caused by the speaker?


Jeff


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/18417024
> 
> 
> This is probably wacky, but I figure if anybody would know, it would be somebody subscribed to this thread. I need to mount a speaker in a location that has no 2x4 wall studs (there's a pocket door) and am considering mounting it on a pipe flanged between the ceiling and the floor. Besides making the pipe strong enough to hold the speaker, would there be any bad vibrations of the pipe caused by the speaker?



Sure...it's possible. It's hard to say if it's likely or not without knowing what speaker it is and what you're doing with it. If it's a satellite, then it's probably fine though.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18417258
> 
> 
> Sure...it's possible. It's hard to say if it's likely or not without knowing what speaker it is and what you're doing with it. If it's a satellite, then it's probably fine though.
> 
> 
> Frank



Full range, but crossed like the others in the system at 80Hz or maybe 100Hz. Material costs will be negligible, so I might as well try it and find out. I'll just go with a 2" OD steel pipe.


Thanks,


Jeff


----------



## kevinzoe




> Quote:
> Originally Posted by *pepar* /forum/post/18417294
> 
> 
> Full range, but crossed like the others in the system at 80Hz or maybe 100Hz. Material costs will be negligible, so I might as well try it and find out. I'll just go with a 2" OD steel pipe.
> 
> 
> Thanks,
> 
> 
> Jeff



Try filling the pipe with sand to add mass to reduce resonances and put some thick/firm rubber (e.g. carpet underlay) at any points where the speaker touches the pipe, again to absorb and prevent any engery transfer.


----------



## Weasel9992




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18417654
> 
> 
> Try filling the pipe with sand to add mass to reduce resonances and put some thick/firm rubber (e.g. carpet underlay) at any points where the speaker touches the pipe, again to absorb and prevent any engery transfer.



+1 for all that. A hollow pipe seems like it would be an instant problem to me.


Frank


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18417654
> 
> 
> Try filling the pipe with sand to add mass to reduce resonances and put some thick/firm rubber (e.g. carpet underlay) at any points where the speaker touches the pipe, again to absorb and prevent any engery transfer.



The sand adds a bit of potential drama to the process, but should be easy to do. The shock mounting of the speaker might be a bit tricky. I was thinking of U-bolting a flat mounting surface onto the pipe and then attaching the Omnimount to that.











I don't thing I could put rubber between the bracket and the pipe and not have it get squeezed out and fairly quickly. Might be able to custom cut a layer or two of old tire inner tube to the outline of the Omnimount though and place it between the plate and the mount. Interesting.... and thanks!


Jeff


----------



## RobG5589

I am considering some possible room treatment in the future. I was hoping I could photo the room and send the pics for evaluation to someone experienced in acoustical treatments. Anyone that has recommendations feel free to share.


Thanks, Rob


----------



## pepar

How do I compare and evaluate the performance of the plethora of diffusors on the market?


Jeff


----------



## Kal Rubinson




> Quote:
> Originally Posted by *RobG5589* /forum/post/18418221
> 
> 
> I am considering some possible room treatment in the future. I was hoping I could photo the room and send the pics for evaluation to someone experienced in acoustical treatments. Anyone that has recommendations feel free to share.
> 
> 
> Thanks, Rob



Most of the regular players in this business will do this for you. Note that their recommendations, while helpful and useful, will include only their products. As a result, it will still be necessary for you to make a difficult comparison.


Also, pix are useful but a precise diagram of room, major features, equipment and listening position(s) should also be supplied.


Try:
www.realtraps.com 
www.gikacoustics.com 
www.acousticsciences.com 
www.auralex.com


----------



## kevinzoe




> Quote:
> Originally Posted by *pepar* /forum/post/18421738
> 
> 
> How do I compare and evaluate the performance of the plethora of diffusors on the market?
> 
> 
> Jeff



Jeff - armed with a little bit of knowledge you will be better apt to critique or evaluate the various types. Have you read Toole's latest book or this text book written by RPG's CEO and Prof Trevor Cox http://www.amazon.ca/Acoustic-Absorb...254199&sr=1-2? 


Firstly, where do you think you want to put diffusion as that'll dictate whether it should be 1D or 2D which will narrow your choices down . . . 1D is recommended for scattering sound latterly (horizontally) and should be placed on the front wall and side walls in front of the listening seat to widen the apparent sound stage width. 2D should be placed on the rear parts of the side walls and rear wall to create a sense of listener envelopment.


Common 1D types include QRD and hemi-cylindrical (and others?) while 2D would include Skylines and derivations thereof.


Secondly, you want the diffuser to work as broad range as possible so as not to act as a low pass filter and throw off your spectral balance that you paid dearly for in your selection of speakers







HF effectiveness for:

* Skylines is determined by the size of the block (not the depth) with small sizes allowing for higher freq diffusion effectiveness. I could only find 1.5" *1.5" blocks of wood for my Skyline which will work up to and likely beyond 4.5KHz which is higher than the highest note on a piano. Even George Massenberg's famous 'Studio C' uses 1"*1" sized blocks which will take it up to 6.75KHz or so . . .

* Hemi-cylindrical diffusers is a funtion of how hard the outer material is (so as not to absorb mid/high frequencies) and the angle of incidence; the max diffusion occurs head-on (meaning perpendicular) to the centre of the hemi.

* QRD is determined by the thickness of the wells with thinner being better.


The diffuser should work down to your room's transition (or Schroeder) frequency which is about 300Hz. LF effectiveness for:

* Skyline is determined by the max cell depth which should be a substantial % of the 300Hz freq wavelength. 50% would mean a depth of 22.6". Of course you could opt for 25% (11.3") or even 14% (6.5") but it would mean less and less effectiveness at 300Hz . . .

* Hemi-Cylindrical is determined by the length of the radius or strickly speaking the 'Sagita' which is that part of the radius that sticks out from the wall into the room when the hemi's arc is less than 180 degrees. The farther out into the room the radius extends the lower the depth it diffuses to. The same calculations would apply as above meaning a radius of 6.5" will only be about 14% of the 300Hz freq wavelength and be less effective than a 11.3" or 22.6" radius.

* QRD well depths determine the LF limits. I've only seen one manufacturer which makes a 15" well depth. Good on them!


Lastly, the diffusion and scattering coefficients are useful metrics for evaluation purposes except that they haven't been standardized nor widely accepted or mandated for inclusion as part of a company's stock marketing collateral for their respective diffusers lines . . .


Hope this tid bit of education has helped.


----------



## Jacob B




> Quote:
> Originally Posted by *pepar* /forum/post/18421738
> 
> 
> How do I compare and evaluate the performance of the plethora of diffusors on the market?
> 
> 
> Jeff



Add me to the list of persons desiring diffusor evaluation!


And which kind is better for a small HT with 7 feet to 1st reflection points and 8 feet to rear wall?


Jacob


----------



## Elill




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18424704
> 
> 
> 1D is recommended for scattering sound latterly (horizontally) and should be placed on the front wall and side walls in front of the listening seat to widen the apparent sound stage width. 2D should be placed on the rear parts of the side walls and rear wall to create a sense of listener envelopment.
> 
> 
> Common 1D types include QRD and hemi-cylindrical (and others?) while 2D would include Skylines and derivations thereof



Kevin, if 1D should be placed in front of the listen e.g. the first reflection point, then why are we seeing an increase in the use of BAD style panels at first reflection points, they are 2D aren't they?


Also, why does Toole advocate absorbers on the front wall and not diffusion? or are you just saying that IF you/I determined we wanted diffusion at those points the ones you outline are the most appropriate?


----------



## Dennis Erskine




> Quote:
> also, why does toole advocate absorbers on the front wall and not diffusion?



sbir


----------



## kevinzoe




> Quote:
> Originally Posted by *Elill* /forum/post/18425941
> 
> 
> Kevin, if 1D should be placed in front of the listen e.g. the first reflection point, then why are we seeing an increase in the use of BAD style panels at first reflection points, they are 2D aren't they?
> 
> 
> Also, why does Toole advocate absorbers on the front wall and not diffusion? or are you just saying that IF you/I determined we wanted diffusion at those points the ones you outline are the most appropriate?




_"why are we seeing an increase in the use of BAD style panels at first reflection points, they are 2D aren't they"_ I might imagine that any number of reasons could account for what you call the "increased use of BAD-style panels at 1st reflection points, including better/smarter RPG marketing, cost savings of combining diffusion & absorption within a single tool, combined diffusion/absorption functionality means less clutter of devices within a room and higher WAF, flavour of the month etc etc.







The RPG BAD panel and BAD ARC are 1-D devices that only scatter sound in one dimension based on the panel's flat or ARC's hemi-cylindrical shape.


Regarding your 2nd question: Toole does in fact recommend absorption in the centre of the front and rear walls to deal with the pressure maxima of the bass nodes similar to what Dennis called SBIR (adjacent boundry effect). His recommendation is within a HT environment, whereas my comment was within a stereo music listening environment - sorry, I likley forgot to mention that assumption up front. my bad. Yes you are correct that IF you wish to put diffusion on the front/side walls then the 1D types that diffuse laterally are the ones most often recommended so as to add spaciousness by widening the apparent source width, which is commohnly seen as a positive thing.


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18424704
> 
> 
> Hope this tid bit of education has helped.



Yes, it does. Thank you. I'll need to bookmark it and return later. Sitting in the parking lot outside the Starbucks in Dickson City isn't conducive to the focus necessary to properly digest all the meat there.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Jacob B* /forum/post/18424875
> 
> 
> Add me to the list of persons desiring diffusor evaluation!



This video lets you hear a variety of diffusors and other surfaces, close-up as if you were in the same room:

All About Diffusion 


--Ethan


----------



## Elill

Thanks all Kevin and Dennis, thats clarrified that for me. Most useful. I was sure BAD's were 2D.....*slap self in head*


There in lies the problem when I want my room for both stereo and HT, well it may not be a problem, I guess we'll see how it goes and then make a judgement on completion










But treating the first side reflections with both a BAD and a QRD would be useful (seperately of course) and then I just see which one works better?


Have we reached agreement on what is classified as "absorptive"? i.e. fiberous v membrane? at the points where Toole states it should be (middle of front and rear walls)?


----------



## Dennis Erskine

There are more than one variety of "BAD" type panels. Clearly there are the RPG BAD Panels. Kinetics has their own similar version and Quest Acoustical has a PerfSorb product, which frankly, I like a lot better than the other two.


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18427343
> 
> 
> This video lets you hear a variety of diffusors and other surfaces, close-up as if you were in the same room:
> 
> All About Diffusion
> 
> 
> --Ethan



And they are helpful, Ethan. But it is like understanding spelling of a foreign language without comprehending the syntax. The video really doesn't aid in coming up with A Plan based on what someone hears and measures _in their room_.


It does show that that YOU understand the various treatments.










Jeff


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18424704
> 
> 
> Jeff - armed with a little bit of knowledge you will be better apt to critique or evaluate the various types. Have you read Toole's latest book or this text book written by RPG's CEO and Prof Trevor Cox http://www.amazon.ca/Acoustic-Absorb...254199&sr=1-2?
> 
> 
> Firstly, where do you think you want to put diffusion as that'll dictate whether it should be 1D or 2D which will narrow your choices down . . . 1D is recommended for scattering sound latterly (horizontally) and should be placed on the front wall and side walls in front of the listening seat to widen the apparent sound stage width. 2D should be placed on the rear parts of the side walls and rear wall to create a sense of listener envelopment.
> 
> 
> Common 1D types include QRD and hemi-cylindrical (and others?) while 2D would include Skylines and derivations thereof.
> 
> 
> Secondly, you want the diffuser to work as broad range as possible so as not to act as a low pass filter and throw off your spectral balance that you paid dearly for in your selection of speakers
> 
> 
> 
> 
> 
> 
> 
> HF effectiveness for:
> 
> * Skylines is determined by the size of the block (not the depth) with small sizes allowing for higher freq diffusion effectiveness. I could only find 1.5" *1.5" blocks of wood for my Skyline which will work up to and likely beyond 4.5KHz which is higher than the highest note on a piano. Even George Massenberg's famous 'Studio C' uses 1"*1" sized blocks which will take it up to 6.75KHz or so . . .
> 
> * Hemi-cylindrical diffusers is a funtion of how hard the outer material is (so as not to absorb mid/high frequencies) and the angle of incidence; the max diffusion occurs head-on (meaning perpendicular) to the centre of the hemi.
> 
> * QRD is determined by the thickness of the wells with thinner being better.
> 
> 
> The diffuser should work down to your room's transition (or Schroeder) frequency which is about 300Hz. LF effectiveness for:
> 
> * Skyline is determined by the max cell depth which should be a substantial % of the 300Hz freq wavelength. 50% would mean a depth of 22.6". Of course you could opt for 25% (11.3") or even 14% (6.5") but it would mean less and less effectiveness at 300Hz . . .
> 
> * Hemi-Cylindrical is determined by the length of the radius or strickly speaking the 'Sagita' which is that part of the radius that sticks out from the wall into the room when the hemi's arc is less than 180 degrees. The farther out into the room the radius extends the lower the depth it diffuses to. The same calculations would apply as above meaning a radius of 6.5" will only be about 14% of the 300Hz freq wavelength and be less effective than a 11.3" or 22.6" radius.
> 
> * QRD well depths determine the LF limits. I've only seen one manufacturer which makes a 15" well depth. Good on them!
> 
> 
> Lastly, the diffusion and scattering coefficients are useful metrics for evaluation purposes except that they haven't been standardized nor widely accepted or mandated for inclusion as part of a company's stock marketing collateral for their respective diffusers lines . . .
> 
> 
> Hope this tid bit of education has helped.



Thanks again, Kevin. I will check the linked book. I have read Toole's paper on reflections (I forget the title right now) and ... wow, are these guys ever "proud" of this book! I have Geddes's book sitting here to go through after I finish one from Tom Holman. Not sure I'll be dropping $150 on the one you linked though ...


I recently changed my front speaker locations to be very close to ear level and can reduce the left and right front absorbers from 48" x 48" to 24" x 48". Above that, on the now exposed carpeted wall above them, I'd like to add 1D diffusors. I do have 48" x 96" absorber on the front ceiling that could be trimmed down in size, too. And I have an absorber on the rear wall. I'd consider replacing that with some sort of diffusion, but the addition of that absorber made the largest improvement in the sound quality of my theater, so I have some anxiety about doing that.


I'll read your excellent Diffusors 101 post and decide on what I might want to try. I think it would be 1D everywhere but the ceiling.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/18431461
> 
> 
> Not sure I'll be dropping $150 on the one you linked though ...
> 
> Jeff



It's more of a text book and not really a "guide" to anything. I have found some useful equations in it for other purposes in modelling, but you really start getting into the nitty gritty of things. Chris's (Audyssey) book is even worse. Those books are really geared for folks seeking a MS in Acoustical Engineering. If you love differential equations, those books are for you, but most things you need to know can be found in the Master Handbook of Acoustics and to some degree, Toole's book, but I found Toole's book to be more of a compilation of his work (almost autobiographical of a life's work) rather than a true "how to" book. If I were to point out a specific useful book to people, it would be the Master Handbook of Acoustics. Best wishes!


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18432775
> 
> 
> It's more of a text book and not really a "guide" to anything. I have found some useful equations in it for other purposes in modelling, but you really start getting into the nitty gritty of things. Chris's (Audyssey) book is even worse. Those books are really geared for folks seaking MS's in Acoustical Engineering. If you love differential equations, those books are for you, but most things you need to know can be found in the Master Handbook of Acoustics and to some degree, Toole's book, but I found Toole's book to be more of a compilation of his work (almost autobioraphical of a life's work) rather than a true "how to" book. If I were to point out a specific useful book to people, it would be the Master Handbook of Acoustics. Best wishes!



Differential equations are why I did not become an Electrical Engineer.










Thanks. I'll muddle through.


Jeff


----------



## StuBerger

I am a newbie here when it comes to acoustics and I have upgraded my speakers and now am interested in acoustical treatment...

We own a smaller house that I remodeled and plan on only staying a few more years but would like to get some suggestions/help on the room from hell we use for the HT....

There is alot of openings and windows and would like to get any helpful ideas on waht to do to get the most sound from the room.

I am enclosing a drawing of the room with the furniture and equipment...any and all recommendations are GREATLY appreciated!


Note: I have two subs and due to wife and room constraints the subs are both up front but I am planning on getting two more and putting them on the opposite rear wall corners as well.


----------



## snb778

wow what a thread fellas


----------



## Ethan Winer




> Quote:
> Originally Posted by *StuBerger* /forum/post/18434635
> 
> 
> would like to get any helpful ideas on waht to do to get the most sound from the room.



The basics are:


* Proper setup, including placing things symmetrically for good imaging.


* Bass traps to even out the low end, and remove boominess at some bass frequencies and nulls at others.


* Absorption at the side-wall and ceiling reflection points to improve clarity.


Much more here:

How to Setup a Room 


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *StuBerger* /forum/post/18434635
> 
> 
> Note: I have two subs and due to wife and room constraints the subs are both up front but I am planning on getting two more and putting them on the opposite rear wall corners as well.



Just to add to Ethan's wisdom, I'd try some different locations for those subs. The corners might not be the best place for them. Try positioning them using prime numbers...like 1/5th the width of the room and 1/7th the length. Just a thought.










Frank


----------



## dooomi

Quick question regarding front wall treatments.


I use in-wall speakers for my fronts... should I still treat the front wall for absorbtion??

What should I be doing to avoid causing issues with the in-wall speakers (do I need to leave a certain amount of space around them with no treatments, etc...).


Also, I've read through the thread... but there is just a ton of information. I know diffusers are preferred on the rear wall. But, can I use the same acoustic treatment panels I apply in the front; to the back if I cannot do actual diffusers at this time? Or would I be better off using a rockwool type material for the front/side walls and a batting type material for the rear walls?


Ok, one last question for now. I know it's not recommended to treat the ceiling, but for aesthetics I need to do something. One reason is I get a good amount of light reflected onto the ceiling when I use the projector and I would like to eliminate this. Is there a material I can buy for the ceiling to wrap with the same fabric as the rest of my panels that will not cause any issues?


I know these are newbie questions, but that's exactly what I am with regard to acoustic treatments.


Thanks in advance for any assistance!


EDIT: This room is purely for home theater, no 2 channel audio going on.


----------



## gye

This is a great thread with lots of information!


I understand that the first priority should be to treat the corners with bass traps. However, that doesn't seem to apply when the room is not symmetric, which is my case.


This is the listening area (length: 19ft, width: 12ft, height: 8ft), which has a large opening on the left side. On the right side, there is a window up front and a sliding glass door on the back.











Here's a view of the left-side opening:











My budget is somewhere between $300 and $600 and aesthetics are important.


I'm thinking the best option is 4-deep decorative panels in the front wall behind the speakers. Does that sound like a good plan? What would you guys do?


----------



## StuBerger




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18442410
> 
> 
> The basics are:
> 
> 
> * Proper setup, including placing things symmetrically for good imaging.
> 
> 
> * Bass traps to even out the low end, and remove boominess at some bass frequencies and nulls at others.
> 
> 
> * Absorption at the side-wall and ceiling reflection points to improve clarity.
> 
> 
> Much more here:
> 
> How to Setup a Room
> 
> 
> --Ethan



I am stuck with where I can put my subs due to wife and room constraints...

I have been looking into bass traps and am planning on picking some out as well as something as a reflection absorption but I do have problems with room opening and placement of those!

I have already contacted Real Traps...are you psychic?


----------



## StuBerger




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18442723
> 
> 
> Just to add to Ethan's wisdom, I'd try some different locations for those subs. The corners might not be the best place for them. Try positioning them using prime numbers...like 1/5th the width of the room and 1/7th the length. Just a thought.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Frank



I have my subs 8 1/4" from each side wall and 6" from the front walls (rear of sub)...I am limited since I have a room opening near the left sub...and due to room constraints and wife, corners are the only place until we move, to put them!


----------



## glaufman




> Quote:
> Originally Posted by *gye* /forum/post/18446461
> 
> 
> What would you guys do?



I would take some scans of the room response to see where best to put that budget, and consider a DIY approach as opposed to buying commercial ones, to help stretch that budget.


----------



## StuBerger

If this helps...here is what I am working with (and stuck with...) I did notice this thread in Home Theater Shack and would like to build these bass traps but due to the window being so close to the front speakers/sub, I would either have to do something narrower or treat with additional wall treatments...from the pics does anyone have suggestions...on the room and what I could do...until we move in a couple years!


----------



## belzarrath




> Quote:
> Originally Posted by *StuBerger* /forum/post/18447001
> 
> 
> If this helps...here is what I am working with (and stuck with...) I did notice this thread in Home Theater Shack and would like to biuld these bass traps but due to the window being so close to the front speakers/sub, I would either have to do something narrower or treat with additional wall treatments...from the pics does anyone have suggestions...on the room and what I could do...until we move in a couple years!



Is there an attic or another room above the ceiling?

If its an attic look into Infinite baffle subwoofer. For more information on IB subs go to http://ibsubwoofers.proboards.com/in...?board=general .


----------



## StuBerger




> Quote:
> Originally Posted by *belzarrath* /forum/post/18447462
> 
> 
> Is there an attic or another room above the ceiling?
> 
> If its an attic look into Infinite baffle subwoofer. For more information on IB subs go to http://ibsubwoofers.proboards.com/in...?board=general .



No, there was attic directly above but I had put in a room/dormer up there.

However, all the walls and ceilings are insulated..used R13 in walls and R30 in ceiling joists. Under the house is a skirted crawl space...no basement or anything!


I already own subs....


----------



## dooomi

I apologize for bumping my own post, but I'm really looking to get the ball rolling on my treatments. The part I'm most concerned with is how to treat the front wall since I use in wall speakers. But, any help with anything would be extremely appreciated.


Thanks!



> Quote:
> Originally Posted by *dooomi* /forum/post/18443638
> 
> 
> Quick question regarding front wall treatments.
> 
> 
> I use in-wall speakers for my fronts... should I still treat the front wall for absorbtion??
> 
> What should I be doing to avoid causing issues with the in-wall speakers (do I need to leave a certain amount of space around them with no treatments, etc...).
> 
> 
> Also, I've read through the thread... but there is just a ton of information. I know diffusers are preferred on the rear wall. But, can I use the same acoustic treatment panels I apply in the front; to the back if I cannot do actual diffusers at this time? Or would I be better off using a rockwool type material for the front/side walls and a batting type material for the rear walls?
> 
> 
> Ok, one last question for now. I know it's not recommended to treat the ceiling, but for aesthetics I need to do something. One reason is I get a good amount of light reflected onto the ceiling when I use the projector and I would like to eliminate this. Is there a material I can buy for the ceiling to wrap with the same fabric as the rest of my panels that will not cause any issues?
> 
> 
> I know these are newbie questions, but that's exactly what I am with regard to acoustic treatments.
> 
> 
> Thanks in advance for any assistance!
> 
> 
> EDIT: This room is purely for home theater, no 2 channel audio going on.


----------



## Ethan Winer




> Quote:
> Originally Posted by *dooomi* /forum/post/18443638
> 
> 
> I use in-wall speakers for my fronts... should I still treat the front wall for absorbtion?



Probably not. Even with normal speakers, the front wall is not usually the most important place to worry about:

Front Wall Absorption 



> Quote:
> What should I be doing to avoid causing issues with the in-wall speakers (do I need to leave a certain amount of space around them with no treatments, etc...).



The basics of acoustic treatment are bass traps in corners plus absorbers at the side-wall and ceiling reflection points. So again, absorbers on the front wall are not usually needed.



> Quote:
> Also, I've read through the thread... but there is just a ton of information.



Not only too much info, but conflicting and often wrong info.












> Quote:
> I know diffusers are preferred on the rear wall. But, can I use the same acoustic treatment panels I apply in the front; to the back if I cannot do actual diffusers at this time?



Yes, absorption works well on the rear wall.



> Quote:
> I know it's not recommended to treat the ceiling, but for aesthetics I need to do something.



Actually, the ceiling reflection points are very important to treat! More here that may help:

How to set up a room 
Early Reflections 



> Quote:
> I know these are newbie questions, but that's exactly what I am with regard to acoustic treatments.



Tons more info here:

Acoustics FAQ 
RealTraps Articles 
RealTraps Videos 


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *StuBerger* /forum/post/18447001
> 
> 
> If this helps...here is what I am working with (and stuck with...) I did notice this thread in Home Theater Shack and would like to build these bass traps but due to the window being so close to the front speakers/sub, I would either have to do something narrower or treat with additional wall treatments...from the pics does anyone have suggestions...on the room and what I could do...until we move in a couple years!



Stu, you might want to try something like this . It's easier to make them fit into a room like yours aesthetically speaking.


Frank


----------



## dooomi




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18459826
> 
> 
> Probably not. Even with normal speakers, the front wall is not usually the most important place to worry about:
> 
> *Not only too much info, but conflicting and often wrong info*.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Thanks a bunch, this will be a huge help!


And yes, one of the issues I've run in to while going through this thread is a TON of conflicting information. It's hard to decide what really makes sense and what doesn't. I'll check out all of the links.


But, I do have one more quick question regarding the front walls. I do want to get some sort of fabric up there so it will tie in with the rest. Since I do not want absorption, could I just use a thin foam batting covered in fabric... or could that be detrimental to my sound?


Thanks again!


----------



## Ethan Winer




> Quote:
> Originally Posted by *dooomi* /forum/post/18459923
> 
> 
> could I just use a thin foam batting covered in fabric... or could that be detrimental to my sound?



You could just glue the fabric directly to the sheet rock. Nothing else is needed. I'd avoid thin batting because that will absorb very high frequencies possibly skewing the balance in the room. The best type of absorption is broadband, working over as wide a range of frequencies as possible.


--Ethan


----------



## eiger

Hi Guys,


Sorry in advance for the large post. I finally got to spend some time futzing with REW.


Room - 26 x 16 x 8.

Gear Onkyo 805

Klipsch Icons

Klipsch Sub 10

Emotiva Side and Rear Surrounds.


Room has it's own sets of challenges. Mostly asymetry of the front wall between the Left and Right front stage. There is also pergo at the main stage. Carpeting covers the back half of the room and listening position. GIK 242 Panels along left and right side walls at reflection areas.


Let me know how these initial graphs look to you guys and if it looks remotely accurate or if I'm missing something completely. The stuff at 80hz is bothering me a bit. Look at that big azz null. Couple people have mentioned potential phasing issues. I just did the default sweep with all speakers connected. Sub turned on.


I need some fellow super geeks to tell me how to interpret this stuff better than I can.


First one is with no smoothing turned on











Second with smoothing










A waterfall I generated.


----------



## eiger

Update


Green Graph shows what happens when sub is turned OFF!


----------



## Dennis Erskine

To determine if that is a modal null, move the microphone at least 3 feet in a diagonal direction and measure again. If you have your cross over set to 80 hz, that could be because your sub is 180 degrees out of phase from your mains at 80 Hz.


----------



## Terry Montlick

Are you not using a crossover to direct all low frequencies to your sub? If so, this is just asking for phase interaction problems. There are solutions, but they can be quite tricky.


----------



## smokarz

hi everyone, i am looking for some bass traps and absorbers to help treat my movie room. i've looked at sites lite realtraps, gik, etc. though they have great stuff, i just simply can't afford them.


can you point me to some diy alternatives that can be done cheaply? thanks!


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18476405
> 
> 
> hi everyone, i am looking for some bass traps and absorbers to help treat my movie room. i've looked at sites lite realtraps, gik, etc. though they have great stuff, i just simply can't afford them.
> 
> 
> can you point me to some diy alternatives that can be done cheaply? thanks!



Try here . Linked in my sig is the process I went through to add treatments ...


Jeff


----------



## smokarz

thanks pepar.


the bass trap diy instruction is awesome.


question, is owens 703 still the preferred material for diy bass trap? is this something i can easily obtain at a local lowes or home depot? if there are better materials, please do tell. thanks!


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18477292
> 
> 
> thanks pepar.
> 
> 
> the bass trap diy instruction is awesome.
> 
> 
> question, is owens 703 still the preferred material for diy bass trap? is this something i can easily obtain at a local lowes or home depot? if there are better materials, please do tell. thanks!



Seven-O-three or something like it . I think it's a safe bet that home improvement stores do NOT have these materials. The pink-n-fluffy stuff is not the same. These acoustical treatment materials come from the "HVAC world" and to buy them - DIY







- you need to get them from an HVAC insulation distributor such as this one .


Jeff


----------



## NJ Jackals

Pepar-


I commented on that link in another thread but maybe this is a better place for it.


I assumed that the OC703 and JM814 were superior to the Linacoustic RC since they are twice as dense (3 pcf vs 1.5 pcf). That's not the case though according to the data from your link. I added the Knauf numbers in the table below directly from their website.


No OC locally, but I was able to find the Knauf sheets locally for $68 for 20 sheets of 1" or 10 sheets of 2". Is this price reasonable?


Also, given the data below, wouldn't linacoustic be the product of choice since it shows as being equivelent in performance and I'm guessing a roll of linacoustic is a lot easier to work with than the OC703?


Productthicknessdensity125hz250hz500hz1000hz2000hz4000hzNRCOC 703, plain1" (25mm)3pcf (48kg/m3)0.110.280.680.90.930.960.7JM Linacoustic RC1" (25mm)0.080.310.640.840.971.030.7JM 8141" (25mm)3pcf (48kg/m3)0.060.290.750.991.041.020.75Knauf Insulation board1" (25mm)3pcf (48kg/m3)0.080.230.620.880.960.990.65


----------



## pepar




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18478178
> 
> 
> Pepar-
> 
> 
> I commented on that link in another thread but maybe this is a better place for it.
> 
> 
> I assumed that the OC703 and JM814 were superior to the Linacoustic RC since they are twice as dense (3 pcf vs 1.5 pcf). That's not the case though according to the data from your link. I added the Knauf numbers in the table below directly from their website.
> 
> 
> No OC locally, but I was able to find the Knauf sheets locally for $68 for 20 sheets of 1" or 10 sheets of 2". Is this price reasonable?



FWIW, about two years ago I paid $125 for a bundle of 2" 703 consisting of twelve sheets x 24" x 48". I'm pretty sure that the 3pcf stuff is what is recommended by the experts.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18478178
> 
> 
> Pepar-
> 
> 
> I commented on that link in another thread but maybe this is a better place for it.
> 
> 
> I assumed that the OC703 and JM814 were superior to the Linacoustic RC since they are twice as dense (3 pcf vs 1.5 pcf). That's not the case though according to the data from your link. I added the Knauf numbers in the table below directly from their website.
> 
> 
> No OC locally, but I was able to find the Knauf sheets locally for $68 for 20 sheets of 1" or 10 sheets of 2". Is this price reasonable?
> 
> 
> Also, given the data below, wouldn't linacoustic be the product of choice since it shows as being equivelent in performance and I'm guessing a roll of linacoustic is a lot easier to work with than the OC703?



Where I use the J-M Linacoustic product, I think installation was more easily accomplished with it than 703.


Jeff


----------



## NJ Jackals




> Quote:
> Originally Posted by *pepar* /forum/post/18478446
> 
> 
> Where I use the J-M Linacoustic product, I think installation was more easily accomplished with it than 703.
> 
> 
> Jeff



Did you fasten it in any fashion or just use spray adhesive. Am I interpreting the numbers correctly in that the Linacoustic is equivalent in performance to the rigid insulation boards?


----------



## pepar




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18478578
> 
> 
> Did you fasten it in any fashion or just use spray adhesive. Am I interpreting the numbers correctly in that the Linacoustic is equivalent in performance to the rigid insulation boards?



I used drywall screws.







It's behind a false wall and it is the 2" Linacoustic.


Rigid insulation board? Which product it that on the charts?


----------



## NJ Jackals




> Quote:
> Originally Posted by *pepar* /forum/post/18479444
> 
> 
> Rigid insulation board? Which product it that on the charts?



I was referring to OC703, JM814, or the Knauf equivalent. (all the other guys on my chart besides the Linacoustic)


----------



## pepar




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18479563
> 
> 
> I was referring to OC703, JM814, or the Knauf equivalent. (all the other guys on my chart besides the Linacoustic)



It is a wee bit more absorbent at 125Hz, but neither are very effective in that area making bass traps a necessity anyway. I think the 250Hz number is more important and that is where the 703 is about 33% more absorbent. And the 703 is 14% more absorptive at 500Hz. My room, anyway, needed 200Hz to 500Hz absorption and my guess is that so do a lot of others.


----------



## NJ Jackals

Should the ceiling and/or floor behind the screen wall be treated as well?


----------



## pepar




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18481121
> 
> 
> Should the ceiling and/or floor behind the screen wall be treated as well?



My main concern when treating behind my false wall was comb-filtering. That is said to be less of an issue with the woven screen I have now over the micro-perforated one I had previously, but the front wall is also a first reflection point and I would have treated there anyway.


Sorry for the blather; I covered the ceiling but not the floor ... one of the two parallel surfaces. I am not an acoustician, though, so that is only my opinion.


Jeff


----------



## smokarz

this is sad. can't get OC 703 anywhere locally. home depot requires a 60/80 piece minimum for special orders.


none of the OC distributors in my areas carry the 700 series. they too would have to special order. this stinks.


my only option is online order for 2-3x the price. ahhh....


btw, i assume that you can use OC 703 for both bass trap (corncers) as well as absorbers (sidewalls/ceilings)?


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18481872
> 
> 
> this is sad. can't get OC 703 anywhere locally. home depot requires a 60/80 piece minimum for special orders.
> 
> 
> none of the OC distributors in my areas carry the 700 series. they too would have to special order. this stinks.
> 
> 
> my only option is online order for 2-3x the price. ahhh....
> 
> 
> btw, i assume that you can use OC 703 for both bass trap (corncers) as well as absorbers (sidewalls/ceilings)?



Shipping charges will kill you, too, by ordering online. Where are you located?


----------



## smokarz

06110


----------



## smokarz

LOL. This is a ripoff.


One of my local distributors quoted me $258+tax for a bundle (12 pieces) of 2x24x48 OC 703.


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/18481872
> 
> 
> this is sad. can't get OC 703 anywhere locally. home depot requires a 60/80 piece minimum for special orders.
> 
> 
> none of the OC distributors in my areas carry the 700 series. they too would have to special order. this stinks.
> 
> 
> my only option is online order for 2-3x the price. ahhh....
> 
> 
> btw, i assume that you can use OC 703 for both bass trap (corncers) as well as absorbers (sidewalls/ceilings)?



Yeah... I've been trying to find a source on and off for years. I'm in 95472.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18481928
> 
> 
> 06110



Closest in CT is Stratford. http://www.spi-co.com/directory.html 


One in Chester, NY, too.


Call and get a quote.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/18482164
> 
> 
> Yeah... I've been trying to find a source on and off for years. I'm in 95472.



Benecia, CA down around the bay.

http://www.spi-co.com/directory.html


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/18482211
> 
> 
> Benecia, CA down around the bay.
> 
> http://www.spi-co.com/directory.html



Totally cool! Thanks so much. I can drive my truck there and pick up a bunch.


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/18482196
> 
> 
> Closest in CT is Stratford. http://www.spi-co.com/directory.html
> 
> 
> One in Chester, NY, too.
> 
> 
> Call and get a quote.



thanks pepar. man that is going to be one long drive.


----------



## smokarz

btw, i want the "PLAIN" type right?


they also have the ASJ (white) and FKS (silver). not sure what the differences are.


EDIT: i called and was quoted $54 for 6 piece (woot). the other two types were $80/85.


----------



## NJ Jackals




> Quote:
> Originally Posted by *smokarz* /forum/post/18482714
> 
> 
> btw, i want the "PLAIN" type right?
> 
> 
> they also have the ASJ (white) and FKS (silver). not sure what the differences are.
> 
> 
> EDIT: i called and was quoted $54 for 6 piece (woot). the other two types were $80/85.



Yes, get the plain. ASJ and FRK are different kinds of facings. The plain is unfaced.


----------



## Vinculum




> Quote:
> Originally Posted by *pepar* /forum/post/18478425
> 
> 
> FWIW, about two years ago I paid $125 for a bundle of 2" 703 consisting of twelve sheets x 24" x 48". I'm pretty sure that the 3pcf stuff is what is recommended by the experts.
> 
> 
> Jeff



I just bought mine from the exact same place as Pepar and was charged $168.92 for 2 bundles of 2" 703, After reading this I'm getting worried that I ordered the right stuff! It should be in this week, but with surgery in the morning I doubt I'll pick it up till next week.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18482663
> 
> 
> thanks pepar. man that is going to be one long drive.



C'mon, man. CT is just not that big.


----------



## pepar




> Quote:
> Originally Posted by *Vinculum* /forum/post/18482976
> 
> 
> I just bought mine from the exact same place as Pepar and was charged $168.92 for 2 bundles of 2" 703, After reading this I'm getting worried that I ordered the right stuff! It should be in this week, but with surgery in the morning I doubt I'll pick it up till next week.



Yes, I should reiterate that my purchase was at the beginning of '08. Today, $168 seems like a good deal. Two fifty-eight, not so much.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18482714
> 
> 
> btw, i want the "PLAIN" type right?
> 
> 
> they also have the ASJ (white) and FKS (silver). not sure what the differences are.
> 
> 
> EDIT: i called and was quoted $54 for 6 piece (woot). the other two types were $80/85.



Killer price if that's 2" x 24" x 48" for unfaced.


Jeff


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/18483279
> 
> 
> C'mon, man. CT is just not that big.



you have no idea. we're only allowed to drive 55mph.


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/18483319
> 
> 
> Killer price if that's 2" x 24" x 48" for unfaced.
> 
> 
> Jeff



yes, that's a bundle of 6 pc 2" x 24" x 48" plain.

unfortunately, it's currently out of stock. they need to put in an order.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18483441
> 
> 
> yes, that's a bundle of 6 pc 2" x 24" x 48" plain.
> 
> unfortunately, it's currently out of stock. they need to put in an order.



Hmmm, I wonder how much they charge WHEN THEY HAVE SOME?


----------



## Weasel9992




> Quote:
> Originally Posted by *Vinculum* /forum/post/18482976
> 
> 
> I just bought mine from the exact same place as Pepar and was charged $168.92 for 2 bundles of 2" 703, After reading this I'm getting worried that I ordered the right stuff! It should be in this week, but with surgery in the morning I doubt I'll pick it up till next week.



That's not too bad...that works out to about $85 for 12 boards of 2" 703. It's more than Pepar paid a few years ago, but it's still a pretty great price.


Frank


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/18483447
> 
> 
> Hmmm, I wonder how much they charge WHEN THEY HAVE SOME?



lol. you could be surprised.


i just called back to place an order and the guy said their other branch has some in stock. he's going to get them transfer some over.


the new price? $71 for 96 sf of OC 703 2" x 24" x 48" (or 12 pieces).


i plan on having my brother pick them up on Fri so we'll see.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/18483644
> 
> 
> lol. you could be surprised.
> 
> 
> i just called back to place an order and the guy said their other branch has some in stock. he's going to get them transfer some over.
> 
> 
> the new price? $71 for 96 sf of OC 703 2" x 24" x 48" (or 12 pieces).
> 
> 
> i plan on having my brother pick them up on Fri so we'll see.



Be aware that 24" x 24" x 48" is TWO FEET x TWO FEET x FOUR FEET!







Up close and personal, it is HUGE. I can tell you that it was real struggle to get two of them into an SUV.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/18483279
> 
> 
> C'mon, man. CT is just not that big.





> Quote:
> Originally Posted by *smokarz* /forum/post/18483428
> 
> 
> you have no idea. we're only allowed to drive 55mph.



Yeah. I tend to drive a little faster and I run out of state every Sunday night!


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18483832
> 
> 
> Yeah. I tend to drive a little faster and I run out of state every Sunday night!



Are they chasing you?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18483832
> 
> 
> Yeah. I tend to drive a little faster and I run out of state every Sunday night!





> Quote:
> Originally Posted by *pepar* /forum/post/18483846
> 
> 
> Are they chasing you?



I didn't say that I *get* run out of state but, rather, at cruising speed, I am very quickly at the border and into NY.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18483994
> 
> 
> I didn't say that I *get* run out of state but, rather, at cruising speed, I am very quickly at the border and into NY.



Oh, Kal, I would have thought that they were chasing you to get you back.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/18484014
> 
> 
> Oh, Kal, I would have thought that they were chasing you to get you back.



They're chasing me all right. After decades of getting away (with it), I got speeding tix in CT and NY in recent months. It is hard to slow down.


----------



## NJ Jackals




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18485662
> 
> 
> They're chasing me all right. After decades of getting away (with it), I got speeding tix in CT and NY in recent months. It is hard to slow down.



What do you drive? I feel like me BMW 335xi has a bullseye on it. Even with my V1.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18485678
> 
> 
> What do you drive? I feel like me BMW 335xi has a bullseye on it. Even with my V1.



Nothing notable. MB C320 Station Wagon(!)


----------



## erkq




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18485678
> 
> 
> What do you drive? I feel like me BMW 335xi has a bullseye on it. Even with my V1.



Try an M5. The cop who pulled me over knew a lot about it. He was a car nut. Part of my protestation was "but it won't even DO 65 in 2nd." He said, "Yeah it will" and smiled like he knew I was trying to put one over on him.


BTW, I was in a 50mph zone.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *erkq* /forum/post/18485698
> 
> 
> Try an M5. The cop who pulled me over knew a lot about it. He was a car nut. Part of my protestation was "but it won't even DO 65 in 2nd." He said, "Yeah it will" and smiled like he knew I was trying to put one over on him.
> 
> 
> BTW, I was in a 50mph zone.



My best experience was a while back when a cop stopped me as I was leaving the Cross County Expwy. He cited me for speeding and changing lanes without signaling. I immediately responded by challenging the latter as I am an assiduous signaler and never fail at that. In a surprise, he immediately backed off and reduced the whole ticket failure to signal which is a misdemeanor and not reported to the insurance company. Cheap, too.


----------



## pepar




> Quote:
> Originally Posted by *NJ Jackals* /forum/post/18485678
> 
> 
> What do you drive? I feel like me BMW 335xi has a bullseye on it. Even with my V1.


 Electronic countermeasures .


----------



## glaufman




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18485662
> 
> 
> They're chasing me all right. After decades of getting away (with it), I got speeding tix in CT and NY in recent months. It is hard to slow down.



They've really gotten bad in recent months, haven't they?

That's why I love the get-out-of-jail-free card my nephew the State Trooper gave me...


Dang I love that kid!


----------



## smokarz

what is everyone using as fabric for the panel? i've been hearing a bit about the JoAnn's grill cloth?


do you have the exact product number for this? i went to JoAnn, asked an old lady there about it but she looked like she had no idea what i was talking about.


----------



## MarkMac




> Quote:
> Originally Posted by *smokarz* /forum/post/18488041
> 
> 
> what is everyone using as fabric for the panel? i've been hearing a bit about the JoAnn's grill cloth?
> 
> 
> do you have the exact product number for this? i went to JoAnn, asked an old lady there about it but she looked like she had no idea what i was talking about.



It's a little on the pricey side, but Guilford of Maine FR701 material is very popular.


----------



## smokarz

thanks, that is indeed pricey.


i have a 50% off coupon from JoAnn and was hoping to pick up some of this 'grill cloth'


----------



## Weasel9992




> Quote:
> Originally Posted by *smokarz* /forum/post/18493692
> 
> 
> thanks, that is indeed pricey.
> 
> 
> i have a 50% off coupon from JoAnn and was hoping to pick up some of this 'grill cloth'



I mean, just about anything that's breathable will work. I'm not sure Joann's would sell something quite as specific as grill cloth. I've never seen in there...I could be wrong of course.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18493911
> 
> 
> I mean, just about anything that's breathable will work. I'm not sure Joann's would sell something quite as specific as grill cloth. I've never seen in there...I could be wrong of course.
> 
> 
> Frank



Yeah, make sure to get the right thing. Half off something that doesn't work is no bargain!


Jeff


----------



## eiger

Guys,


Treating the screen wall with GIK 242s behind the L and R tower speakers.


Towers = 41"

Panels = 49"


Is there a general rule of thumb of the fraction of speaker height for my specific placement? What do you reccomend? 1/3 above?


Having the top of the panel flush with the top of the screen would be nice, but not required.


Also - What tips and tricks have people used for their ceiling mounted panels?


----------



## zeshane

Hey all,


I need some help in the treatment of sound for my entertainment room. I have attached the layout of the room. Cant do much with windows, glass door which leads to the balcony and the in-wall fitted cupboard. But I can cover the windows and the glass door with thick curtains. The floor will be carpeted wall-to-wall. The only other option as I see fit are to mount two sound deadning panels at the back and right wall from the seating position. Where I live, sound proofing is a mute concept and therefore most of the pro material is unavailable. I'll need some basic solutions to put the wall mounts in place.


I was thinking of using 1 inch thick, 3 x 2 ft plywood panels with normal 1 - 1.5 inch thick foam glued to it. To round it off, thin piece of decorative cloth covering the foam nailed/stapled at the back of plywood.


I need ideas on the size of the plywood (or whether plywood is a good option or is there another surface I can use?) and type of foam to glue to the plywood.


I will also use two down facing lights above each panel to make it look attractive.


Looking forward to ideas.


Zeeshan

Attachment 173123


----------



## Jacob B




> Quote:
> Originally Posted by *Jacob B* /forum/post/18368976
> 
> 
> Count me among the confused as well.
> 
> I based my plan (not done yet) on the first 150 pages as well, when concensus seemed to be something like:
> 
> - 1st reflection treatment with absorbtion (1" OC703) from floor and up to 4' - from screen and two thirds back into room.
> 
> - 2" OC703 on whole front wall behind false screen wall
> 
> - Bass traps in corners - as many corners as possible.
> 
> - As this is an attic room, I have sloping ceiling, starting from 5½' up the side walls. Therefore, I will treat the sloping ceiling as well with 2" OC703 in 3.5" deep frames, each panel measuring 40" x 6" on the inside. They will be mounted as vertical strips, with 8" of air between each panel. The will give 1st reflection absorption and crude difussion.
> 
> - I also consider 2-3 QRD Diffusor (from Real Traps) for the center back wall - with 6" absorption (OC703) as fallback - the QRDs are expensive...
> 
> 
> The whole discussion about using a mirror etc to find first reflections seems to me to be for HT with two seats or something like that - for a dedicated HT room with multiple seats and two rows or more, the first reflection points are going to be all over the place.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have two rows of four seats, second row on a riser.
> 
> 1st reflections from the three identical front speakers pretty much include most of the sidewall as described above in plan...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Now, my room is small - 13.4' x 20' x 8'. It's my understanding (based on this thread, Real Traps and GIK homepages etc) that *diffusion works best in larger rooms* (or rather, when the listener is far away from the diffusor).
> 
> 
> When [many people - edit] now mention diffusion for 1st reflection points, instead of absorption - *does that go for a small room like mine as well?*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And what kind of diffusion products for this specific task?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Cheers from Denmark,
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jacob





> Quote:
> Originally Posted by *Jacob B* /forum/post/18424875
> 
> 
> Add me to the list of persons desiring diffusor evaluation!
> 
> 
> And which kind is better for a small HT with 7 feet to 1st reflection points and 8 feet to rear wall?
> 
> 
> Jacob



Would any one care to sum it up ?


----------



## Jacob B




> Quote:
> Originally Posted by *nathan_h* /forum/post/18372545
> 
> 
> My room is similar to yours (17'x12.5'x7.5' -- nice of you to translate into feet rather than use metrics...) but even a little smaller.
> 
> 
> I have two rows of seats: one couch for each. The second row couch is on a riser.
> 
> 
> Using the mirror method I was able to cover the side wall first reflection points for all three front speakers for almost all sitting positions with just two 2'x'4 panels on each of the side walls.
> 
> 
> That, plus bass trapping in every corner and under the screen (ie, where the screen wall meets the floor), please two more panels on the back wall, and heavy carpet on the floor, have really made things solid and clear. Yet most of the wall space is still uncovered.



thanks for sharing your experiences!










Jacob b


----------



## johnbomb

I have a question for the experts regarding the "double bass array", discussed here:

http://www.avsforum.com/avs-vb/showthread.php?t=837744 


Does it cancel room modes from all 3 directions (front/back wall, side/side wall, and floor/ceiling), or just the front/back modes? I know the description says that it works on all modes, but I'd appreciate a bit more explanation.


Thanks,

John


----------



## Terry Montlick

All modes. By having subwoofer arrays in both front and back, you create waves which travel only from front to back, essentially eliminating widthwise and heightwise modes. If you look up the "image source method" for modeling acoustic shoeboxes, you'll see that the speakers are reflected in side walls, ceiling, and floor. This makes, with proper subwoofer placement, perfect symmetry for not exciting these modes.


So all that's left are the lengthwise modes. That's where the DBA really does its magic. Any wave that hits the back wall gets automatically "sucked up" by the rear subwoofers, eliminating all reflection. This obviously requires careful level adjustment. But it works!


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *eiger* /forum/post/18494924
> 
> 
> Guys,
> 
> 
> Treating the screen wall with GIK 242s behind the L and R tower speakers.
> 
> 
> Towers = 41"
> 
> Panels = 49"
> 
> 
> Is there a general rule of thumb of the fraction of speaker height for my specific placement? What do you reccomend? 1/3 above?
> 
> 
> Having the top of the panel flush with the top of the screen would be nice, but not required.
> 
> 
> Also - What tips and tricks have people used for their ceiling mounted panels?



1/3 above works great.


For ceiling hanging, I like to use #8 sheet rock anchors and #8 hooks, then use zip ties to secure the panel to the hooks.


Frank


----------



## korkster

I'm in the process of finishing up my basement theater; completed the fabric install over the weekend. I have been using an acoustic plan that Brian Pape put together for me with the standard 2" treatement (Linacoustic) covering the front wall, 1" treatment from floor to ceiling on the side walls about four feet back from the front for first reflections, and then 5' high the rest of the way to the back wall. The back wall is covered with 2" of OC 703 for bass absorbtion, and then a foil scrim over that to reflect the highs and mids. I also have two floor to ceiling bass traps in the front corners made up of 2' square pieces of 5" thick cotton.


I haven't had much time to actually sit and listen to things during construction, although I did some two channel listening when I first finished up the acoustic treatments and was pretty impressed with how things sounded, especially the "soundstage." Vocals were dead center and clear. However, last night I "listened" to some of the Eagles "Hell Freezes Over" concert DVD in multi-channel DTS (I don't have the projector hung yet so I just listened), and I have to say I was somewhat disappointed. The center channel material, mainly vocals, seemed almost muted. As I was contemplating this while sitting in a chair, I put my hands behind my head and noticed it sounded a bit clearer. I then "cupped" my hands behind my ears, and the sound seemed much more dynamic. Long story to my question, but is my room too dead, or is there something else that's going on? One concern is that the ceiling is only 7' as this is a basement build in an older home. Could that be contributing to it?


After all of this work I'm really hoping I haven't screwed things up.







I also realize that the "HFO" DVD is not exactly audiophile quality.


----------



## nathan_h

Brian was one of the experts I consulted (and bought from) when putting together my room, and his advise was very helpful.


I'll let others weigh in on whether you have perhaps too much thin treatment, and not enough thick (broadband) treatment, but I assume Brian received detailed measurements of your room, including furniture and speaker layout, and made the recommendations based on those details.


The real way to tell if the room is too dead is to measure it. There are some tools discussed in this and other threads, some of which require your laptop, a mic + preamp + some free software. Other options probably exist if, for example, you have an iPhone and want to buy an app for that.


That said, while I don't know the DVD you are speaking about, one thing about a good room is that you will readily hear imperfections in recordings now. I know that poor ADR in movies and TV shows is now glaringly apparent in my room.... whereas before it was masked by the poor room.


----------



## johnbomb




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18508079
> 
> 
> All modes. By having subwoofer arrays in both front and back, you create waves which travel only from front to back, essentially eliminating widthwise and heightwise modes. If you look up the "image source method" for modeling acoustic shoeboxes, you'll see that the speakers are reflected in side walls, ceiling, and floor. This makes, with proper subwoofer placement, perfect symmetry for not exciting these modes.
> 
> 
> So all that's left are the lengthwise modes. That's where the DBA really does its magic. Any wave that hits the back wall gets automatically "sucked up" by the rear subwoofers, eliminating all reflection. This obviously requires careful level adjustment. But it works!
> 
> 
> - Terry



Thanks, Terry. I'm in the process of building one of these things, with 4 15" drivers on the front and back walls, respectively. Further, these drivers will be mated to ported, closet sized enclosures, about 140 cubic feet per wall. Each box of 4 drivers will be tuned to around 14hz, using the "large and low tuned" guidlines (LLT) found at hometheatershack.com.


I also saw that you ran a simulation on a double bass array a few years ago and concluded that it wasn't a "magic bullet", but was pretty good.

http://www.avsforum.com/avs-vb/showthread.php?t=942585 


In this simulation, did you run the exact same output signal through both the front and back walls (with delay and 180 degrees of phase shift), or did you go further and adjust the rear wall signal to compensate for losses from simulated room objects/people?


Thanks,

John


----------



## pepar




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18508079
> 
> 
> All modes. By having subwoofer arrays in both front and back, you create waves which travel only from front to back, essentially eliminating widthwise and heightwise modes. If you look up the "image source method" for modeling acoustic shoeboxes, you'll see that the speakers are reflected in side walls, ceiling, and floor. This makes, with proper subwoofer placement, perfect symmetry for not exciting these modes.
> 
> 
> So all that's left are the lengthwise modes. That's where the DBA really does its magic. Any wave that hits the back wall gets automatically "sucked up" by the rear subwoofers, eliminating all reflection. This obviously requires careful level adjustment. But it works!



Terry, does your answer apply to any front/back sub setup or just the one with subs in the wall, aka DBA?


----------



## korkster




> Quote:
> Originally Posted by *nathan_h* /forum/post/18511882
> 
> 
> Brian was one of the experts I consulted (and bought from) when putting together my room, and his advise was very helpful.



Yes, Brian's been great, and I haven't bounced (no pun intended







) this phenomena off of him at this point. I'm also not completed with the room as there is no carpet in there yet, nor furniture. I'm hoping that it will all come together when that happens.


----------



## nathan_h

With acoustics design, in a conventional room, there is no need to "hope". You can come up with a very solid plan with very predictable results. I would definitely share your impressions with him.


----------



## ToBeFrank




> Quote:
> Originally Posted by *korkster* /forum/post/18511584
> 
> 
> The center channel material, mainly vocals, seemed almost muted. As I was contemplating this while sitting in a chair, I put my hands behind my head and noticed it sounded a bit clearer. I then "cupped" my hands behind my ears, and the sound seemed much more dynamic.



Are you able to easily remove some of your treatments? You might try removing the panels for the first reflections. Toole presents very good evidence in his book Sound Reproduction for not treating first reflections as it adds to the spaciousness and speech intelligibility. I know when I added treatments for the first reflections I immediately got the "muted" impression that you got. I removed those treatments as I didn't like it and then read Toole's book which sealed it for me. He also states that if you do want to treat the first reflections to use at least 4" absorption or you'll throw off the spectral balance.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18515119
> 
> 
> Are you able to easily remove some of your treatments? You might try removing the panels for the first reflections. Toole presents very good evidence in his book Sound Reproduction for not treating first reflections as it adds to the spaciousness and speech intelligibility. I know when I added treatments for the first reflections I immediately got the "muted" impression that you got. I removed those treatments as I didn't like it and then read Toole's book which sealed it for me. He also states that if you do want to treat the first reflections to use at least 4" absorption or you'll throw off the spectral balance.



There are many products currently on the market that address this issue, and it isn't quite as black and white as broadband absorption or bare wall. You may also want to consider using a Perfsorber or Binary Amplitude Diffsorber. These products preserve much of the higher frequency energy but also treat for frequencies that cause smearing due to path differences. The timing difference is a main source of reduced speech intelligibilty. Toole is correct in the fact that absorbing the higher frequencies is less desirable, but using some type of diffusion/absorber combination is preferable IMHO. Best wishes!


----------



## ToBeFrank




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18515159
> 
> 
> There are many products currently on the market that address this issue, and it isn't quite as black and white as broadband absorption or bare wall. You may also want to consider using a Perfsorber or Binary Amplitude Diffsorber. These products preserve much of the higher frequency energy but also treat for frequencies that cause smearing due to path differences. The timing difference is a main source of reduced speech intelligibilty.



Toole actually devotes an entire chapter in his book to countering this very argument.



> Quote:
> Toole is correct in the fact that absorbing the higher frequencies is less desirable, but using some type of diffusion/absorber combination is preferable IMHO. Best wishes!



You'll have to forgive me if I give much more weight to the opinion of the guy who presents mountains of evidence and studies (many his own) in a 500+ page book versus a guy on an internet forum.


----------



## korkster

I just finished stapling all of the fabric on over the treatments so removing anything would be a real cramp, and a bit premature.


I think that I've got to do some more serious listening with a variety of recordings to get a better idea; like I said, 2-chanel sounds pretty good. And I've got to talk to Bryan as well. He based the design on some very specific room measurements I gave to him when I started. I could always experiment with placing some hard surface material against the walls (plywood, or something) to see what difference it might make. I was just curious as to the phenomena of things sounding better with my hands cupped behind my ears, and what that might indicate as far as room acoustics go.


I guess I could always figure out some kind of headband to wear that would push my ears forward .


----------



## nathan_h

Good idea.


Here's a couple of more thoughts:


1. About Toole: There are dozens of pages of experts in various topics here on AVS talking about the particularities of the Toole results, including important clarifications from his co-researchers. Luckily, you can try it both ways and see what works for you. There is no single correct answer. Your results on the face of it contradict Toole -- since you like the two channel sound with the side treatments -- and fall in line with how much music and film soundtracks are mastered.


2. Related to #1 perhaps, in terms of trying things out: You may be used to hearing music reproduced in sub-optimal ways (it was true of me) so give any change a few weeks of listening before making a decision. And in the end, trust your ears.


----------



## heavyflyr

I posted this on a separate thread and am hoping someone can help. I would really like the best treatment for controlling bass. Right now (totally un-treated), it is boomy (sp?), not tight etc. I have read many threads on this subject, however, the below has me confused.



Thank you,


B.



Hi,


I have been reading about room treatments for some time (read: eyes are bleeding) and frankly I am confused. I am building a small dedicated home theater that is 16x10x8. It has a soffit all around the perimeter. I have Klipsch THX Ultra 2 "horn" loaded speakers behind an acoustically transparent screen. I have two of the KSW 12" subs. Most of the information I have read suggests that a smallish room will need to control bass more than say a larger room. I was planning on making a couple of the "super chunk" type traps for behind the screen, however, after having read your comments here it seams as though I may do a better job with cotton. Is this so? If so, how would you suggest I apply this material? Behind the screen?


Second, someone also mentions that having "horn" loaded speakers negate the need for first reflection point treatment (perhaps I am inferring incorrectly). This is the first I have read of this. Care to elaborate?


Thank you,


B.


----------



## belzarrath

Hello, My basemant just got finalized by the inspector so I'm getting ready for the treatment of my HT.

Front wall and 1st reflection obsorbtion I see most people using OC703, I can not get this in my area, I have spent many hours wasting sales time requesting information.

What can I get, 3" rock wool, and an OEM product that is the same as oc703.

I also found Knauf duct liner and Plenum http://www.knaufusa.com/products/com...liner_e-m.aspx 


It seem the 2" duct liner would be better for obsorbtion than oem or rock wool.

The knauf duct liner is the same price as rock wool or oem, $1.00 square ft.

Should I go with the Knauf duct liner?


----------



## korkster




> Quote:
> Originally Posted by *nathan_h* /forum/post/18516182
> 
> 
> 
> 2. Related to #1 perhaps, in terms of trying things out: You may be used to hearing music reproduced in sub-optimal ways (it was true of me) so give any change a few weeks of listening before making a decision. And in the end, trust your ears.



I think you're right; I need to give it some time and a lot more testing before I get too concerned. Thanks for your time and thoughts Nathan.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18515204
> 
> 
> Toole actually devotes an entire chapter in his book to countering this very argument. You'll have to forgive me if I give much more weight to the opinion of the guy who presents mountains of evidence and studies (many his own) in a 500+ page book versus a guy on an internet forum.



You were offering an opinion, I was offering an alternative opinion. Toole's book is not the be all end all. There are many theories and opinions (including other piles of evidence) that deal with lateral reflections. Why don't you try reading other people's work, including Dr. D'Antonio, or other opinions before you jump to definitive conclusions. Best wishes!


----------



## Terry Montlick




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18515204
> 
> 
> You'll have to forgive me if I give much more weight to the opinion of the guy who presents mountains of evidence and studies (many his own) in a 500+ page book versus a guy on an internet forum.



I respect Floyd Toole, but there are equally experienced professionals who disagree with him. They are just not as vocal about it. Floyd likes to stir the pot!







And there are some things he can say in his book which he cannot say in a refereed journal paper, because he simply doesn't have the scientific proof.


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18519640
> 
> 
> I respect Floyd Toole, but there are equally experienced professionals who disagree with him. They are just not as vocal about it. Floyd likes to stir the pot!
> 
> 
> 
> 
> 
> 
> 
> And there are some things he can say in his book which he cannot say in a refereed journal paper, because he simply doesn't have the scientific proof.



Exactly. Nothing but respect for Floyd Toole, but just know that there's a lot of debate about his findings.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18522246
> 
> 
> Exactly. Nothing but respect for Floyd Toole, but just know that there's a lot of debate about his findings.
> 
> 
> Frank



I must admit to be experiencing the debate .. in my own head. I know what I heard before, during and after adding FRP absorbers to my room, but yet here's this respected researcher whose findings contradict what I've heard.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/18522465
> 
> 
> I must admit to be experiencing the debate .. in my own head. I know what I heard before, during and after adding FRP absorbers to my room, but yet here's this respected researcher whose findings contradict what I've heard.
> 
> 
> Jeff



There is absolutely nothing wrong with approaching this in an empirical manner. My recommendation is to try all suggestions and physically understand what is happening before formulating an opinion. I have formulated my own opinion based on this idea. It does not mean mine is absolutely the correct one. I believe the point here is to stick with what you feel you is best, but always remain open minded about new methods, scientific evidence or ideas. The mark of a good scientist. Best wishes!


----------



## ToBeFrank




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18519422
> 
> 
> You were offering an opinion,



Nope. I was giving him an option, and the reasoning behind the option, to help him figure out why he didn't like his sound. The opinion is Toole's and backed up by Toole.



> Quote:
> I was offering an alternative opinion.



Exactly. So I give way more weight to Toole's than yours. When your book comes out I'll give you more weight.











> Quote:
> Toole's book is not the be all end all. There are many theories and opinions (including other piles of evidence) that deal with lateral reflections. Why don't you try reading other people's work, including Dr. D'Antonio, or other opinions before you jump to definitive conclusions. Best wishes!



You jumped to conclusions that I haven't done any other reading. Toole's opinion just happened to match up with what I liked in my room. And I discovered that before I even read Toole's book.


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/18522465
> 
> 
> yet here's this respected researcher whose findings contradict what I've heard.



There are respected researchers on both (several?) sides of this debate. And when one digs into how the conclusions were drawn, one can get a sense of how to weight the apparently contradictory conclusions.


I don't want to beat a dead horse but the proof is in the listening, and one answer does not fit all people and situations.


For me, in addition to listening tests (ie, living with each scenario), I also researched a bit about how the recordings I listen to were mastered -- both in terms of the room the creation took place in, the treatments and specs for how the sound is reproduced, and in terms of speaker placement, etc. I am trying to hear what the sound designer and mastering engineers intended and heard -- and not, for example, a more spacious soundstage than they heard or intended.


Of course, even with that goal and process, there is more than one way to get there -- and many many ways to get "close" (which is what I'd say I have done, rather than getting a perfect simulacrum, based on feedback from a professional engineering and a pro musician who have experienced my system).


----------



## pepar

The big question that is foremost in my mind with Dr Toole's research on this - and maybe I missed it in his paper - is what was the content his research subjects listened to - music or cinema? If music, classical or pop?


Beyond that, I've done everything I can to remove the room's "environment" from the system's sound so that the artist's "environment" could be heard and he is saying the room adds something desirable.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18522764
> 
> 
> Nope. I was giving him an option, and the reasoning behind the option, to help him figure out why he didn't like his sound. The opinion is Toole's and backed up by Toole. Exactly. So I give way more weight to Toole's than yours. When your book comes out I'll give you more weight.
> 
> 
> 
> 
> 
> 
> 
> You jumped to conclusions that I haven't done any other reading. Toole's opinion just happened to match up with what I liked in my room. And I discovered that before I even read Toole's book.



You are certainly entitled to your opinion. Best wishes!


----------



## ToBeFrank




> Quote:
> Originally Posted by *pepar* /forum/post/18523294
> 
> 
> Beyond that, I've done everything I can to remove the room's "environment" from the system's sound so that the artist's "environment" could be heard and he is saying the room adds something desirable.



From reading Toole's book, one of his main points is there is a spaciousness to music that needs to be recreated during playback. The two channel stereo playback needs the early reflections to increase the spaciousness to sound more like the original music and to what sounds natural to us. He states that it is up to the listener to decide whether to treat early reflections for multichannel since multichannel can recreate the spaciousness. People can agree or disagree with his findings... I'm just stating what he concludes.


----------



## pepar




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18523914
> 
> 
> From reading Toole's book, one of his main points is there is a spaciousness to music that needs to be recreated during playback. The two channel stereo playback needs the early reflections to increase the spaciousness to sound more like the original music and to what sounds natural to us. He states that it is up to the listener to decide whether to treat early reflections for multichannel since multichannel can recreate the spaciousness. People can agree or disagree with his findings... *I'm just stating what he concludes*.



I know, I know.










You seem a good interpreter, so let me follow up with an observation that spaciousness, if even a small home theater can add such a thing, comes from the reflections and resulting reverberant field arriving _after_ the 20ms or so time frame during which reflections are interpreted as part of the direct sound event, but are delayed enough so that they confuse instead of merging.


So, what sayeth Dr Toole on first reflections, early reflections and reverberance?


----------



## ToBeFrank




> Quote:
> Originally Posted by *pepar* /forum/post/18524095
> 
> 
> I know, I know.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You seem a good interpreter, so let me follow up with an observation that spaciousness, if even a small home theater can add such a thing, comes from the reflections and resulting reverberant field arriving _after_ the 20ms or so time frame during which reflections are interpreted as part of the direct sound event, but are delayed enough so that they confuse instead of merging.
> 
> 
> So, what sayeth Dr Toole on first reflections, early reflections and reverberance?



Actually, I didn't do a good job. There is way more involved than just the spaciousness. Needless to say he spends a large part of the book on the precedence effect. It is more complex than "does the reflection arrive before or after 20ms?" There really is no way I could summarize it. Even if you don't end up agreeing with him, I'd recommend getting the book. If anything one gains perspective on the whole issue... by an expert, not from joe schmoes like myself.


----------



## pepar




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18524376
> 
> 
> Actually, I didn't do a good job. There is way more involved than just the spaciousness. Needless to say he spends a large part of the book on the precedence effect. It is more complex than "does the reflection arrive before or after 20ms?" There really is no way I could summarize it. Even if you don't end up agreeing with him, I'd recommend getting the book. If anything one gains perspective on the whole issue... by an expert, not from joe schmoes like myself.



jeff schmoe vs. frank schmoe?










I have his paper, but very little of it is in English.


----------



## Terry Montlick




> Quote:
> Originally Posted by *pepar* /forum/post/18512370
> 
> 
> Terry, does your answer apply to any front/back sub setup or just the one with subs in the wall, aka DBA?



Only DBA. The sound sources have to be on a grid which is no coarser than 1/2 the highest wavelength between centers. Otherwise, you will not get this nice unidirectional flow of waves from front to back. So with anything above subwoofer frequencies, this gets impractical pretty quickly! Also, with higher frequencies, such a front to back wave flow is not desirable. You want these sounds bouncing around and coming from different directions for a variety of reasons.


----------



## Elill

People talk about competing ideas to Toole's work and say they've "got proof", but I am yet to see a reference (as in a scientific paper not Ethan’s video) - can someone point me in the right direction to the following issue -


- Toole says you need membrane absorbers in corners due to an argument around particle velocity v pressure


Obviously there are quite a few people that use fibrous absorbers over membrane traps. I need to understand the maths behind that versus Toole's point of view.


----------



## SierraMikeBravo

Hi Elill,


I don't have any specific reference to guide you to other than a simple physics text book (many answers to understanding audio can be found in one), but the physics is easy enough to understand. Here is how I usually explain it to people. Do you understand the process of reverse osmosis? If you do, understand that it only works when the water on one side is under pressure. The membrane is just big enough to allow water molecules to pass through while leaving the minerals behind due to their size. In essence, that is what is going on along a boundary. Particles are at their slowest speed...indeed...maybe even close to zero. However, they have a bunch of other particles piling up behind them with continued energy input. Since the particles have nowhere to go due to the boundary...the pressure begins to increase. So, we have high pressure, but very slow if not zero velocity. Away from the boundary, it is just the opposite...higher velocity...lower pressure (although the particles are actually at their slowest on the peaks and nulls (think of a pendulum). So, frictional based absorbers work best when the particle is moving (hence the term frictional implying velocity), membrane type absorbers work best when there is higher pressure. This, of course, is an explanation in its simplest form, but I think explanation enough. It really is simple physics. Best wishes!


----------



## Elill

Thanks SMB, I get that, so why do people put frictional absorbers in corners then?


----------



## SierraMikeBravo

Frictional absorbers are low cost and more readily available in comparison and they are effective...just not as effective as membranes. Best wishes!


----------



## Elill

How much "less effective" are they? this is what I have been trying to quantify


----------



## Terry Montlick

Elill,


For textbooks covering this subject in general, see "Room Acoustics," by Heinrich Kuttruff, chapter 6, and "Acoustic Absorbers and Diffusers," by Cox, chapters 5-7.


Something to bear in mind about membrane absorbers is they are inherently tuned to some range of optimal frequencies. This is not a free choice, but is greatly constrained by the depth of the absorber.


- Terry


----------



## Dennis Erskine

Significantly less effective for low frequencies! Still effective for high frequencies. A general target is a frictional (velocity type) absorber needs to have a depth equal to, or greater than, a 1/4 wavelength. Some of these corner frictional absorbers have a vinyl barrier between a couple of layers of the fuzzy stuff...that creates a pressure type absorber. In fact if you take two layers of 1" fuzzy stuff and put it on a wall, you'll get absorption down to frequency "x". If you now put a very thin sheet of vinyl or plastic between those two layers, the absorber suddenly starts performing more like 4" of fuzzy stuff.


Let me give you a slightly better mental picture of pressure vs velocity. Find a very solid wall. Concrete for example. Stand 3 meters from the wall. Now run as fast as you can directly toward this wall. When you hit the wall, your velocity is zero but you're feeling a lot of pressure.


----------



## Elill

Thanks Terry, I have the Cox book somewhere, I'll have a read....again.


So if I were to go down the DIY treatment route, it'd be "give it a go" take some measurements, see if it worked, repeat if/until desired results are acheived.


OR


Alternatively I can just buy off the shelf products which have been tested and "proven".....DIY isn't looking like a good option especially when its only about $1k cheaper for the entire room.....again the curse of buying stuff here...


That said I'll file that suggestion Dennis, it could work well on the under side of my soffits, I had planned on stuffing 100mm or 4" there, so this might save a little height - cant hurt right?


I did a chem. major so SMB's explanation makes perfect sense....not quite as exciting as your suggestion to run at a wall though


----------



## Terry Montlick

Yes, SierraMikeBravo gave a very good explanation, as did Dennis.


Don't assume that off-the-shelf products are "proven." They may just have "proven sales," which ain't the same thing!


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *dennis erskine* /forum/post/18526772
> 
> 
> let me give you a slightly better mental picture of pressure vs velocity. Find a very solid wall. Concrete for example. Stand 3 meters from the wall. Now run as fast as you can directly toward this wall. When you hit the wall, your velocity is zero but you're feeling a lot of pressure.



lol!


----------



## pepar




> Quote:
> Originally Posted by *Elill* /forum/post/18526886
> 
> 
> So if I were to go down the DIY treatment route, it'd be "give it a go" take some measurements, see if it worked, repeat if/until desired results are acheived.
> 
> 
> OR
> 
> 
> Alternatively I can just buy off the shelf products which have been tested and "proven".....DIY isn't looking like a good option especially when its only about $1k cheaper for the entire room.....again the curse of buying stuff here...



For fiberglass absorbers, the raw material comes from the Heating, Ventilation and Air Conditioning "world." The best prices for that material is always from an HVAC insulation distributor. Specifically avoid any product (or seller) that uses the word "acoustical." For example, the going price for a bale (12 pcs x 2" x 24" x 48") of OC 703 is US$100 - US$150. Do the math.


Just my $.02.


Jeff


----------



## KNKKNK




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18526772
> 
> 
> Stand 3 meters from the wall. Now run as fast as you can directly toward this wall. When you hit the wall, your velocity is zero but you're feeling a lot of pressure.



Where do I sign Up?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Elill* /forum/post/18525481
> 
> 
> People talk about competing ideas to Toole's work and say they've "got proof", but I am yet to see a reference (as in a scientific paper not Ethan's video) - can someone point me in the right direction to the following issue -
> 
> 
> - Toole says you need membrane absorbers in corners due to an argument around particle velocity v pressure



Some of my videos have very conclusive proof! This video shows a substantial improvement in the LF response and ringing to below 40 Hz using only porous type absorbers:

Hearing is Believing 


--Ethan


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18526772
> 
> 
> Let me give you a slightly better mental picture of pressure vs velocity. Find a very solid wall. Concrete for example. Stand 3 meters from the wall. Now run as fast as you can directly toward this wall. When you hit the wall, your velocity is zero but you're feeling a lot of pressure.



Replace the wall with a cliff edge and your can experience the converse: high velocity and very little pressure...................any more.


----------



## unavol




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18526772
> 
> 
> Find a very solid wall. Concrete for example. Stand 3 meters from the wall. Now run as fast as you can directly toward this wall. When you hit the wall, your velocity is zero but you're feeling a lot of pressure.





> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18529354
> 
> 
> Replace the wall with a cliff edge and your can experience the converse: high velocity and very little pressure...................any more.



You guys are serious about room treatment!!!


----------



## heavyflyr




> Quote:
> Originally Posted by *heavyflyr* /forum/post/18516688
> 
> 
> I posted this on a separate thread and am hoping someone can help. I would really like the best treatment for controlling bass. Right now (totally un-treated), it is boomy (sp?), not tight etc. I have read many threads on this subject, however, the below has me confused.
> 
> 
> 
> Thank you,
> 
> 
> B.
> 
> 
> 
> Hi,
> 
> 
> I have been reading about room treatments for some time (read: eyes are bleeding) and frankly I am confused. I am building a small dedicated home theater that is 16x10x8. It has a soffit all around the perimeter. I have Klipsch THX Ultra 2 "horn" loaded speakers behind an acoustically transparent screen. I have two of the KSW 12" subs. Most of the information I have read suggests that a smallish room will need to control bass more than say a larger room. I was planning on making a couple of the "super chunk" type traps for behind the screen, however, after having read your comments here it seams as though I may do a better job with cotton. Is this so? If so, how would you suggest I apply this material? Behind the screen?
> 
> 
> Second, someone also mentions that having "horn" loaded speakers negate the need for first reflection point treatment (perhaps I am inferring incorrectly). This is the first I have read of this. Care to elaborate?
> 
> 
> Thank you,
> 
> 
> B.



Anyone wanna take a break from your uber argument and help me with the above?


B.


----------



## pepar

I think what that person might be alluding to is the directivity/dispersion of a horn speaker being such that either there is nothing striking the first reflection points or that the off-axis response is smooth. I don't know whether that is true or not, but I can point to the rear wall as a first reflection point that might need treatment irregardless of the dispersion of the front speakers. I'd add that if I saw a post like that from someone regarding horn speakers, I'd ask them if they've overlooked the rear wall.







Many people do.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *heavyflyr* /forum/post/18532963
> 
> 
> Anyone wanna take a break from your uber argument and help me with the above?
> 
> 
> B.



I would disagree with the aspect of not treating the first reflection points. However, to determine the type of treatment you would need, you really need to measure the off-axis response. If poor, treat it differently than if the response is good, or a better suggestion is if the off-axis is poor, replace the speakers with a different speaker.


Dealing with your bass is far more complicated. It isn't as simple as throwing treatment in the corner (although that would be nice wouldn't it!







). To be perfectly honest, it is difficult to answer your low frequency problems. We have no idea where your seating is placed, where your speakers are placed in relation to any boundaries, where your subs are placed, and the general make up of the room. These questions need to be answered first.


Generally, low frequency problems are addressed through a number of remedies or some combination thereof. It just depends on what the problem is. Proper seating, sub and speaker placement is crucial. Adding treamtment at strategic points is also an essential element. Once the mechanical elements are dealt with, then parametric equalization is often necessary as the finishing touch.


Be warned though, underestimating parametric EQ is a BIIIIIIIGGGG mistake. Throwing the built in Audyssey or some other automajik as the stop gap could lead to bigger problems. Just be careful and understand the limitations if using such a system.


So, there you have it. Probably not what you were hoping for (a lot more questions than answers), but it will at least help you to start looking in the right places to help you with your bass problems! Best wishes!


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18535809
> 
> 
> 
> Generally, low frequency problems are addressed through a number of remedies or some combination thereof. It just depends on what the problem is. Proper seating, sub and speaker placement is crucial. Adding treamtment at strategic points is also an essential element. Once the mechanical elements are dealt with, then parametric equalization is often necessary as the finishing touch.



I think it is great that home theater designers can select and position seats so as to avoid nulls/peaks, but most of us do not have that luxury as our seats are where they are because of factors like the space we have to work with, the number of seats we want, the size and location of our displays, etc. We usually have some more latitude with sub placement, but not always. As you conclude, this leaves us only with - but greatly increases the importance of - treatments and electronic correction.



> Quote:
> Be warned though, underestimating parametric EQ is a BIIIIIIIGGGG mistake. *Throwing the built in Audyssey* or some other automajik *as the stop gap could lead to bigger problems.* Just be careful and understand the limitations if using such a system.



Do you really mean that using Audyssey could lead to bigger problems or could I have misread? If you really do mean that, then I need to call you on it. OT for this thread, so I'll gladly follow you somewhere else to hear your reply.


Jeff


----------



## Dennis Erskine




> Quote:
> Do you really mean that using Audyssey could lead to bigger problems or could I have misread? If you really do mean that, then I need to call you on it. OT for this thread, so I'll gladly follow you somewhere else to hear your reply.



...and I happen to agree with SMB on this (again OT for this thread). Understand Jeff, he used the word "could" and absolutely any suggestion that Audyssey is the fix all is not correct.


...now back to your regularly scheduled commercial interruption.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18536867
> 
> 
> ...and I happen to agree with SMB on this (again OT for this thread). Understand Jeff, he used the word "could" and absolutely any suggestion that Audyssey is the fix all is not correct.
> 
> 
> ...now back to your regularly scheduled commercial interruption.



Oh well, we're here and it seems to be a slow news day...


I saw the "could" and am interested in knowing what the "bigger problems" would be and what circumstances would bring them on? I understand the arguments against automajik correction technology, but the most I've seen alleged before is that they don't work. This is the first time I've seen somebody warning about _bigger problems_.


Jeff


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/18536902
> 
> 
> Oh well, we're here and it seems to be a slow news day...
> 
> 
> I saw the "could" and am interested in knowing what the "bigger problems" would be and what circumstances would bring them on? I understand the arguments against automajik correction technology, but the most I've seen alleged before is that they don't work. This is the first time I've seen somebody warning about _bigger problems_.
> 
> 
> Jeff



Well, if used improperly, they _*can*_ lead to bigger problems. The huge Audyssey thread is testament to that and, personally, I have misused Audyssey (experimentally) and obtained results which are grossly inferior to bypass. "_The fault, dear Brutus, is not in...._" Audyssey but in the consistent failure of AVR/processor manuals to offer more guidance on its use.


That said, I agree that automatic EQ is not panacea but, used properly, rarely ever leads to inferior performance.


----------



## Dennis Erskine

I can give you two, just off the top of my head, and then let SMB swim on his own:


1. Attempting to compensate for the inability of 1" dome tweeters to get HF to a seating location 15' from the speakers ... pop, pop, pop. Oops.

2. After spending multiple hours setting up four subwoofers (different SPL, phase, positions and xovers) to get rid of a 35Hz null in a really bad location and provide great bass reponse across 8 seats, Audyssey promptly went and put the null back in (on the up side, the Audyessy "off" button worked very well.


----------



## LarryChanin




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18536965
> 
> 
> I can give you two, just off the top of my head, and then let SMB swim on his own:
> 
> 
> 1. Attempting to compensate for the inability of 1" dome tweeters to get HF to a seating location 15' from the speakers ... pop, pop, pop. Oops.



Hi Dennis,


I can appreciate Shawn's point that in some cases, a parametric equalizer in the hands of a pro can do magic. However, is your above remark suggesting that Audyssey can destroy 1" dome tweeters, but manual equalization can make up for the high frequency limitations without damaging them?


Thanks.


Larry


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18536935
> 
> 
> Well, if used improperly, they _*can*_ lead to bigger problems. The huge Audyssey thread is testament to that and, personally, I have misused Audyssey (experimentally) and obtained results which are grossly inferior to bypass. "_The fault, dear Brutus, is not in...._" Audyssey but in the consistent failure of AVR/processor manuals to offer more guidance on its use.
> 
> 
> That said, I agree that automatic EQ is not panacea but, used properly, rarely ever leads to inferior performance.



In general, this is exactly what I mean. The Audyssey system really is designed for the novice...a way to get good sound without knowing a whole lot about it. This is, however, its fatal flaw as Kal just eluded to. Knowing that Audyssey just took you for a trip to the audio dump, it's possible to catch the mistakes...if you don't know...well...then you have problems worse than you started out with. This actually just happened to me last night when I was doing a calibration for a client. I had to manually change several elements. I also agree with Kal that Audyssey can perform very nicely...but it quite often, I found, requires a nearly ideal setup. Throw anything in its way as a road block, and Audyssey often can't handle it.



> Quote:
> then let SMB swim on his own



Now I have no one behind me for the shark's to get. I don't have to be fast...just a little faster than you!


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18537245
> 
> 
> In general, this is exactly what I mean. The Audyssey system really is designed for the novice...a way to get good sound without knowing a whole lot about. This is, however, its fatal flaw as Kal just eluded to. Knowing that Audyssey just took you for a trip to the audio dump, it's possible to catch the mistakes...if you don't know...well...then you have problems worse than you started out with. This actually just happened to me last night when I was doing a calibration for a client. I had to manually change several elements. I also agree with Kal that Audyssey can perform very nicely...but it quite often, I found, requires a nearly ideal setup. Throw anything in its way as a road block, and Audyssey often can't handle it.



.. "designed for the novice" .. "fatal flaw" .. "audio dump" ..


Your conclusion that it may not work in all instances I accept. Ditto that it could create worse problems, e.g. Dennis' tweeter popper scenario, but I take issue with your characterization of it and that a nearly ideal setup is required for it to be any benefit. My experience is 180° out of sync with yours.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/18537318
> 
> 
> .. "designed for the novice" .. "fatal flaw" .. "audio dump" ..
> 
> 
> Your conclusion that it may not work in all instances I accept. Ditto that it could create worse problems, e.g. Dennis' tweeter popper scenario, but I take issue with your characterization of it and that a nearly ideal setup is required for it to be any benefit. My experience is 180° out of sync with yours.



I have no problem with your opinion and experiences.







I have had good success with Audyssey as well, but there are just a few instances where I have had problems (my experience last evening is case in point). I am not trying to open a can of worms here, just offering a word of caution not to take things at face value. That's all. My apologies on any mis-characterizations that you take offense on.


----------



## Jaketh

Hello all, I'd greatly appreciate some feedback on how to treat my ceiling. As you can see in the attached (hopefully), I have treatments on the walls but nothing up top.


The left side of my main listening position has a drop ceiling that is 1' higher than the right side (which is a flat surface). My FR speaker is under the 7.5' high area and my FL speaker is under the 8.5' high drop ceiling.


I'm torn between getting some auralex diffusors or getting some absorption and somehow hanging it on the right side (the lower area). I get listening fatigue failry quickly here and best I can think is it's the reflections from the lower area of the ceiling causing it (it's not volume, etc).


Am I on the right track? Any opinions would be very helpful for me. Thanks,


----------



## nathan_h




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537370
> 
> 
> Hello all, I'd greatly appreciate some feedback on how to treat my ceiling. As you can see in the attached (hopefully), I have treatments on the walls but nothing up top.
> 
> 
> The left side of my main listening position has a drop ceiling that is 1' higher than the right side (which is a flat surface). My FR speaker is under the 7.5' high area and my FL speaker is under the 8.5' high drop ceiling.
> 
> 
> I'm torn between getting some auralex diffusors or getting some absorption and somehow hanging it on the right side (the lower area). I get listening fatigue failry quickly here and best I can think is it's the reflections from the lower area of the ceiling causing it (it's not volume, etc).
> 
> 
> Am I on the right track? Any opinions would be very helpful for me. Thanks,



It's hard to do the geometry from a photograph, but your setup doesn't look too bad. Sure, catching the first reflection ceiling points, rear wall points, and even more corner bass trapping would all help (and I would tackle those in reverse order), but something else may be wrong, if you are experiencing fatigue (which I don't think ceiling panels will solve).


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537370
> 
> 
> I get listening fatigue failry quickly here and best I can think is it's the reflections from the lower area of the ceiling causing it (it's not volume, etc).
> 
> 
> Am I on the right track? Any opinions would be very helpful for me. Thanks,



Do you find it difficult sometimes to understand dialog?


----------



## Jaketh

Oops, forgot to show my rear wall. Here it is (all wall traps are 4" thick)


I am about 11' from the fronts, the back wall is ~2' behind me


----------



## Jaketh




> Quote:
> Originally Posted by *pepar* /forum/post/18537472
> 
> 
> Do you find it difficult sometimes to understand dialog?



Not really; every once in awhile but figured it was the source (for example, had a heckuva time hearing/comprehending some of the lines in the Sherlock Holmes blu-ray but that was an isolated incident).


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537489
> 
> 
> Not really;



To what do you attribute the fatigue?


----------



## Jaketh

2-channel music listening, no doubt - this led me to blame the lower ceiling on the right and the asymmetry...but, I could be grasping...


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537489
> 
> 
> Not really; every once in awhile but figured it was the source (for example, had a heckuva time hearing/comprehending some of the lines in the Sherlock Holmes blu-ray but that was an isolated incident).



I punched up your picture to look at the aiming of your center channel speaker. It *looks* like you have it aimed up a bit. If not, or it still isn't aimed at the listeners' ears, you could raise it more.











I might also temporarily place a nice thick rug on that tile floor. Those two tweaks are free and might give you an indication of what it wrong.


----------



## Jaketh

Nice, made the picture look better! I have it lifted as high as the little feet on the cc-690 will let it go; however, with it being off during listening, wouldnt really contribute to the 2 channel issue.


Thanks for helping me here, btw!


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537523
> 
> 
> Nice, made the picture look better! I have it lifted as high as the little feet on the cc-690 will let it go; however, with it being off during listening, wouldnt really contribute to the 2 channel issue.










No, I guess it wouldn't. I'd still try the rug on the floor though. Hard ceiling and hard floor can't be helping.


----------



## Jaketh

I like the rug idea; it's actually thin carpet (not tile) but doubt it's doing much for me acoustically.


Assuming both a rug and ceiling treatments were equal in cost, would you still start with the floor as a potentially higher trouble spot than my "askew" ceiling?


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537552
> 
> 
> I like the rug idea; it's actually thin carpet (not tile) but doubt it's doing much for me acoustically.
> 
> 
> Assuming both a rug and ceiling treatments were equal in cost, would you still start with the floor as a potentially higher trouble spot than my "askew" ceiling?



I'll beg off on giving acoustical treatment advice, but I will say that if I had *my* walls treated like yours and nothing on the ceiling, that would be *my* next area to treat.







Not sure it'd be for being irregular so much as simply being highly reflective.


Can you attribute your fatigue to anything in particular?


----------



## Jaketh

Thanks pepar, appreciate you taking the time to help me here. I have the same thought but am unsure how to "treat" it...would anyone know whether absorption/diffusion would be more preferred?


----------



## Jaketh




> Quote:
> Originally Posted by *pepar* /forum/post/18537586
> 
> 
> Can you attribute your fatigue to anything in particular?



Not really, just after listening to music for 20-30 mins at moderate levels (65-70 on my shack SPL) I get headachy


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18537594
> 
> 
> Thanks pepar, appreciate you taking the time to help me here. I have the same thought but am unsure how to "treat" it...would anyone know whether absorption/diffusion would be more preferred?



I think this is where the pros would say that you should do some acoustical measurements. Are you familiar with Room EQ Wizard?


----------



## nathan_h

Try turning off any EQ in your system and see if that helps. Try turning off the sub, and see if that helps. Try listening with the door open to the rest of the house. I'd guess that either there is something way high or way low in the audio spectrum that is out of whack, but hard to notice except for the discomfort. Perhaps there is a real big build up of low frequency energy.


Do you have this problem in other listening environments?


----------



## Jaketh

I have EQ off (prefer that sound to the Audyssey in my Denon in either Flat or normal mode). I havent tried with sub of yet. I'll give that a go. No door to shut (back opens to a stairway). Havent really spent time listening critically elsewhere, but havent noticed it (in car, etc) anywhere else


Thanks


----------



## Jaketh




> Quote:
> Originally Posted by *pepar* /forum/post/18537645
> 
> 
> I think this is where the pros would say that you should do some acoustical measurements. Are you familiar with Room EQ Wizard?



Yeah, cursory knowledge, just enough to get this graph


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18538082
> 
> 
> Yeah, cursory knowledge, just enough to get this graph













Now that it made this, try clicking on some of the other tabs. You'd be looking for reverb time and waterfalls, and they would all be generated from that measurement.


----------



## Jaketh

Attached is waterfall and spectral decay. I don't know how to interpret these quite yet...


----------



## Dennis Erskine




> Quote:
> I can appreciate Shawn's point that in some cases, a parametric equalizer in the hands of a pro can do magic. However, is your above remark suggesting that Audyssey can destroy 1" dome tweeters, but manual equalization can make up for the high frequency limitations without damaging them?



No, not at all. The difference is, I know better (I hope anyway). In this case Audyssey didn't and the problem is the user relied upon Audyssey's knowledge ... sometimes automatic has problems. Auto pilots are great tools; but, as I (almost) demonstrate to my students, they'll fly you into the ground or the side of a mountain sure as Carter made little liver pills.


In this case, there were other options available to resolve the problem; but, after pushing the magic button none of those options were available until the physical damage was repaired.


----------



## Jaketh

and the RT60...


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18538161
> 
> 
> and the RT60...













Well I'm not that good at knowing what they mean either, but the big (read: BIG) difference in the lowest bar is not good at all.


Here's a recent one of mine:











Waterfall:


----------



## Jaketh

Wow, big time difference....now, how to fix it....at least this may mean it's not "all in my head" (aside from the pain!)


----------



## Dennis Erskine




> Quote:
> I have EQ off (prefer that sound to the Audyssey in my Denon in either Flat or normal mode).



I recall a recent conversation about how Audyssey ain't at all as good as it cracked up to be.


So these plots are based upon what Audyssey did to your room or are the plots taken with Audyssey disengaged (I'd say off, but, Denon won't let that happen.)


----------



## Jaketh

frankly I dont remember


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18538337
> 
> 
> I recall a recent conversation about how Audyssey ain't at all as good as it cracked up to be.



frankly I dont remember.


----------



## Jaketh

just checked my logs; the ones with and without EQ had very similar waterfalls. The one I posted was the only of my sweeps with the really messed up first bar on the RT60. My waterfall is still the same as before, but the RT60 looks much like yours pepar. This new one was one with "Flat" audyssey


----------



## heavyflyr




> Quote:
> Originally Posted by *pepar* /forum/post/18533051
> 
> 
> I think what that person might be alluding to is the directivity/dispersion of a horn speaker being such that either there is nothing striking the first reflection points or that the off-axis response is smooth. I don't know whether that is true or not, but I can point to the rear wall as a first reflection point that might need treatment irregardless of the dispersion of the front speakers. I'd add that if I saw a post like that from someone regarding horn speakers, I'd ask them if they've overlooked the rear wall.
> 
> 
> 
> 
> 
> 
> 
> Many people do.



Thank you Pepar!


B.


----------



## heavyflyr




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18535809
> 
> 
> I would disagree with the aspect of not treating the first reflection points. However, to determine the type of treatment you would need, you really need to measure the off-axis response. If poor, treat it differently than if the response is good, or a better suggestion is if the off-axis is poor, replace the speakers with a different speaker.
> 
> 
> Dealing with your bass is far more complicated. It isn't as simple as throwing treatment in the corner (although that would be nice wouldn't it!
> 
> 
> 
> 
> 
> 
> 
> ). To be perfectly honest, it is difficult to answer your low frequency problems. We have no idea where your seating is placed, where your speakers are placed in relation to any boundaries, where your subs are placed, and the general make up of the room. These questions need to be answered first.
> 
> 
> Generally, low frequency problems are addressed through a number of remedies or some combination thereof. It just depends on what the problem is. Proper seating, sub and speaker placement is crucial. Adding treamtment at strategic points is also an essential element. Once the mechanical elements are dealt with, then parametric equalization is often necessary as the finishing touch.
> 
> 
> Be warned though, underestimating parametric EQ is a BIIIIIIIGGGG mistake. Throwing the built in Audyssey or some other automajik as the stop gap could lead to bigger problems. Just be careful and understand the limitations if using such a system.
> 
> 
> So, there you have it. Probably not what you were hoping for (a lot more questions than answers), but it will at least help you to start looking in the right places to help you with your bass problems! Best wishes!



SMB,


First, thank you for your detailed response. Second, I apologize for providing such little detail for a rather complicated question.


I will try my best to describe my build...this is a dedicated build in a basement. The room is a perfect rectangle with a single door in the rear wall. The rough dimensions are (16'L 10'W 8'H) I have built a soffit all around the perimeter. My speakers are the Klipsch THX Ultra 2s with two subwoofers. I read a bit about the need for assymetry with regard to LF and as such am considering placing one sub on the right side (facing) proscenium and the other near the left rear wall. I am attaching a few pictures to help. As you can see at this point the room is treatment free. I am open to trying most types of treatment including cotton. Notice there is only one corner in the rear as the other side has a door. How could I bass trap there in lieu of a 90 deg angle?


B.


----------



## pepar

B - two things .. First, what are those three cabinets on the wall? Not for speakers, I hope.


Second, no child labor laws where you are?










Jeff


----------



## johnbomb

What is the current thought on placing angled reflector panels at first reflection points? For example, if I took thick 2x4 foot wooden panels and angled them from the wall at the first reflection points of my center channel, could that help improve dialogue intelligibility? I saw a picture of a listening room with angled panels all over someone's ceiling.


----------



## jsmith967

So I have done about an hour's worth reading this thread and I have examined bobgold's table comparing a wide variety of absorbers. Like many of us, I do not have easy access to rigid fiberglass. Furthermore, as I was examining the comparison table and reading this thread I noticed that after the "6 inch mark" thickness of fluffy fiberglass, it performs very well, even better than the rigid in some cases. My local Home Depot has 9.5" fluffy for cheap. Here is my questions:

- Since it is more cost effective, why do most people not use the fluffy fiberglass since it performs better than the denser yet thinner counter parts? (I am particularly thinking of the numbers comparing 705 4" plain on wall compared to r19, faced 6.25" on wall, i.e. at 125hz .94 vs. .75 respectively). Do people simply choose the rigid (perhaps in the above comparison) not because of cost or performance but structure and space, i.e., they don't have enough room for 6.25" fluffy traps?

- Lastly, if I have room to use 9.5" fluffy for my bass traps and I am NOT going to compress them (I am going to leave them in their "fluffy form") would this be desired for better bass absorption say compared to 705 4"?


Thank you.

Joshua


----------



## pepar




> Quote:
> Originally Posted by *jsmith967* /forum/post/18541105
> 
> 
> Like many of us, I do not have easy access to rigid fiberglass.



Where are you located?


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/18541242
> 
> 
> Where are you located?



It's usually available in larger quantities in larger cities...always available via the interweb (which Al Gore invented) as well.


Frank


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18541582
> 
> 
> It's usually available in larger quantities in larger cities...always available via the interweb (which Al Gore invented) as well.
> 
> 
> Frank



Shipping bulky fiberglass gets very expensive. HVAC insulation distributors are all over the United States, but I guess that there are people who are not within driving distance. I was fortunate to be very close to one. Good thing, too, as I needed to make two trips.


Jeff


----------



## erkq




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18541582
> 
> 
> the interweb (which Al Gore invented).



I'm a card-carrying environmentalist and usually take great umbrage at unnecessary digs at liberals. But I think it's pretty funny we know a Prius will do 100mph because of Al Gore's son!


----------



## heavyflyr




> Quote:
> Originally Posted by *pepar* /forum/post/18540635
> 
> 
> B - two things .. First, what are those three cabinets on the wall? Not for speakers, I hope.
> 
> 
> Second, no child labor laws where you are?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



No worries Jeff. Those are for the speakers as you can see in the last photo. They are inside the the stud bay, heavily secured, sound-proofed and the speakers are front ported.


B.


----------



## pepar




> Quote:
> Originally Posted by *heavyflyr* /forum/post/18541904
> 
> 
> No worries Jeff. Those are for the speakers as you can see in the last photo. They are inside the the stud bay, heavily secured, sound-proofed and the speakers are front ported.
> 
> 
> B.



Speakers sound "honky" when inside of such a cabinet irregardless of their design.


Jeff


----------



## heavyflyr




> Quote:
> Originally Posted by *pepar* /forum/post/18541928
> 
> 
> Speakers sound "honky" when inside of such a cabinet irregardless of their design.
> 
> 
> Jeff



Umm no not at all. They protrude out from the cabinet and are not affected in any way. My concerns are primarily about bass because of the room dimensions.


What does "irregardless" mean?


B.


----------



## jsmith967

I am located in Louisville KY. There are a few commercial supplies that I could contact in order to get a special order for me the consumer. But, availibility was not my primary concern, instead it was on the comparison in both performance and cost. Any thoughts on the comparison and questions I posed? Again, here they are:


Since it is more cost effective, why do most people not use the fluffy fiberglass since it performs better than the denser yet thinner counter parts? (I am particularly thinking of the numbers comparing 705 4" plain on wall compared to r19, faced 6.25" on wall, i.e. at 125hz .94 vs. .75 respectively). Do people simply choose the rigid (perhaps in the above comparison) not because of cost or performance but structure and space, i.e., they don't have enough room for 6.25" fluffy traps?

- Lastly, if I have room to use 9.5" fluffy for my bass traps and I am NOT going to compress them (I am going to leave them in their "fluffy form") would this be desired for better bass absorption say compared to 705 4"?


----------



## pepar




> Quote:
> Originally Posted by *heavyflyr* /forum/post/18541958
> 
> 
> Umm no not at all. They protrude out from the cabinet and are not affected in any way. My concerns are primarily about bass because of the room dimensions.
> 
> 
> What does "irregardless" mean?
> 
> 
> B.



It's the same as "regardless" but sounds more intelligent.







Sort of like "flammable" and "inflammable." OK on your speakers in cabinets, but I wouldn't do it ...


Just my $.02.


Jeff

http://www.avsforum.com/avs-vb/showthread.php?t=990718


----------



## Jaketh

is there any cure for my crazy waterfall? traps, traps, traps?


----------



## pepar




> Quote:
> Originally Posted by *Jaketh* /forum/post/18543700
> 
> 
> is there any cure for my crazy waterfall? traps, traps, traps?



That'd be my path. The low end ringing looks like it goes on forever. The room looks too reverberant in general. Probably why you are getting fatigued.


----------



## ToBeFrank




> Quote:
> Originally Posted by *Jaketh* /forum/post/18543700
> 
> 
> is there any cure for my crazy waterfall? traps, traps, traps?



That and EQ. Your problems in the time domain are all in the low frequency range. You'll get more detail if you look at the waterfall with the bottom of the vertical scale stopping at your noise floor. It looks to be around 35-40dB in your case.



> Quote:
> Originally Posted by *pepar* /forum/post/18544401
> 
> 
> The room looks too reverberant in general.



His room would sound too dead to me.


----------



## notnyt

Hi,


Just wanted to say thanks for all the great info in this thread.


I was able to track down some OC 703 locally for $0.90/sqft and made seven 3'x5' panels to treat my room. The sound difference is amazing. I should have done this long ago. This is by far the cheapest, and most beneficial addition I have done.


I spent about $100 on fabric, $140 on three boxes of insulation, and $80 on wood. The wood costs could be greatly reduced, but I had a few ideas on how to frame them out originally, but the wife liked it better covered.


Anyway, I put up a quick gallery here:

http://countercultured.net/pics/ht/panels/


----------



## pepar




> Quote:
> Originally Posted by *ToBeFrank* /forum/post/18545337
> 
> 
> His room would sound too dead to me.



You think that's background noise beyond 300ms above 200Hz on his waterfall, right?


----------



## Terry Montlick

That is a rather high noise floor. Only about 60 dB S/N. Jaketh, you got some significant HVAC noise going on, perhaps? Looks like a smallish room, so your RT60s in the .25 to 0.30 second range are not at all unreasonable.


----------



## Weasel9992




> Quote:
> Originally Posted by *erkq* /forum/post/18541821
> 
> 
> I'm a card-carrying environmentalist and usually take great umbrage at unnecessary digs at liberals. But I think it's pretty funny we know a Prius will do 100mph because of Al Gore's son!



Oddly enough, so am I. I'm a huge Al Gore fan as a matter of fact. It wasn't meant to be a dig at all. We all say things that are taken the wrong way, and that was a particularly funny one to me, that's all. No offense intended, honestly.










Frank


----------



## pepar

I heard Al keynote at Greenbuild in Phoenix last November. He doesn't take himself too seriously and even made the same joke himself.


Jeff


----------



## nathan_h




> Quote:
> Originally Posted by *notnyt* /forum/post/18545403
> 
> 
> Hi,
> 
> 
> Just wanted to say thanks for all the great info in this thread.
> 
> 
> I was able to track down some OC 703 locally for $0.90/sqft and made seven 3'x5' panels to treat my room. The sound difference is amazing. I should have done this long ago. This is by far the cheapest, and most beneficial addition I have done.



That's a great approach, good results, and a nice looking room.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/18546330
> 
> 
> I heard Al keynote at Greenbuild in Phoenix last November. He doesn't take himself too seriously and even made the same joke himself.
> 
> 
> Jeff



I've heard him say the same thing, which is why I made the crack. Nothing personal.


Frank


----------



## erkq




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18547080
> 
> 
> I've heard him say the same thing, which is why I made the crack. Nothing personal.
> 
> 
> Frank



Sorry. I though I was clear in that I thought your comment was funny. I also though what his son did was funny... AND just a mite irresponsible. We're all human. I never took your comments as lefty-bashing. Sorry to pull the tread OT.


----------



## pepar

We're all good here. Nobody intended to offend.


----------



## Leifashley27

This thread is going to take some serious trips to the bathroom to get through (where all the fine reading is done).


My room has a vaulted ceiling above the seating position and I'm getting some nasty echo (see pic):


Would hanging absorption on the vaulted ceiling and back wall fix this... do I need diffusion anywhere?











Ears are about 40" off the backwall... it's far as I could get with domestic policy.


----------



## Jaketh

leifashley - I'm eager to hear folks' replies to you; just wanted to say I really like your space!


----------



## Jaketh




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18545915
> 
> 
> That is a rather high noise floor. Only about 60 dB S/N. Jaketh, you got some significant HVAC noise going on, perhaps? Looks like a smallish room, so your RT60s in the .25 to 0.30 second range are not at all unreasonable.



It may have been the noise from my computer (the one I used to record my REW measurements).


Do you think my waterfall response is due to that or some other issue?


----------



## Terry Montlick




> Quote:
> Originally Posted by *Jaketh* /forum/post/18549567
> 
> 
> It may have been the noise from my computer (the one I used to record my REW measurements).
> 
> 
> Do you think my waterfall response is due to that or some other issue?



Other than the high noise floor, I don't see anything out of the ordinary in the waterfall graph. What are you referring to?


- Terry


----------



## Jaketh




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18551362
> 
> 
> Other than the high noise floor, I don't see anything out of the ordinary in the waterfall graph. What are you referring to?
> 
> 
> - Terry



Great, that's all I needed to hear! Just seemed like mine was out of whack vs others' but looks like the noise is the cause. Thanks!


----------



## Ethan Winer




> Quote:
> Originally Posted by *Leifashley27* /forum/post/18548024
> 
> 
> Would hanging absorption on the vaulted ceiling and back wall fix this... do I need diffusion anywhere?



If you sit 40 inches in front of a reflecting wall you'll definitely benefit from absorption or diffusion on that wall. Which you choose depends on your budget. Good diffusors cost much more than good absorbers, whether you buy commercial products or DIY. You'll also benefit greatly from bass traps in the corners.


--Ethan


----------



## giomania




> Quote:
> Originally Posted by *Leifashley27* /forum/post/18548024
> 
> 
> This thread is going to take some serious trips to the bathroom to get through (where all the fine reading is done).
> 
> 
> My room has a vaulted ceiling above the seating position and I'm getting some nasty echo (see pic):
> 
> 
> Would hanging absorption on the vaulted ceiling and back wall fix this... do I need diffusion anywhere?
> 
> 
> Ears are about 40" off the backwall... it's far as I could get with domestic policy.



I suppose you can always try to have the Minister of the Interior re-write the domestic policy. Sometimes, a bribe from the Bureau of Mineral Deposits is required to re-write said policy.


----------



## Terry Montlick

If you add some slanted reflectors on the walls, you can use hanging absorber clouds or baffles for the vault area for sound absorption. This can work very well. But the WAF usually prohibits this.


----------



## Leifashley27




> Quote:
> Originally Posted by *giomania* /forum/post/18558952
> 
> 
> I suppose you can always try to have the Minister of the Interior re-write the domestic policy. Sometimes, a bribe from the Bureau of Mineral Deposits is required to re-write said policy.



It's amazing how fast the effects from the Bureau of Mineral Deposits wear off. You would think the 3ct diamond wedding ring would have bought me many more years. Maybe the General of Fruited Spirits be heavily present when I get the "ok."



> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18559026
> 
> 
> If you add some slanted reflectors on the walls, you can use hanging absorber clouds or baffles for the vault area for sound absorption. This can work very well. But the WAF usually prohibits this.



I've thought of this very thing along with a few panels on the ceiling.



> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18553692
> 
> 
> If you sit 40 inches in front of a reflecting wall you'll definitely benefit from absorption or diffusion on that wall. Which you choose depends on your budget. Good diffusors cost much more than good absorbers, whether you buy commercial products or DIY. You'll also benefit greatly from bass traps in the corners.
> 
> 
> --Ethan



Thanks for the reply Ethan... I'm going to try to get my REW waterfall done tonight so I can post. I was thinking of doing the QRD diffusers on the backwall to help since we're so close to it.


----------



## gravi




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/18559026
> 
> 
> If you add some slanted reflectors on the walls, you can use hanging absorber clouds or baffles for the vault area for sound absorption. This can work very well. But the WAF usually prohibits this.



What is the consensus for treating rooms with vaulted ceilings in general? My dedicated room has vaulted ceilings on all four sides. So far I have done bass traps in the corners, first reflection on side walls,and absorption below and to the sides of the screen. Do vaulted ceilings need special treatment or are they just part of the ceiling?


----------



## Ethan Winer




> Quote:
> Originally Posted by *gravi* /forum/post/18560933
> 
> 
> Do vaulted ceilings need special treatment or are they just part of the ceiling?



A peaked ceiling focuses sound to the area underneath the peak. Focusing is generally considered bad, but if nobody sits there it might be okay. I put absorbers under the peak in my home recording studio room as shown below.


--Ethan


----------



## gravi




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18563729
> 
> 
> A peaked ceiling focuses sound to the area underneath the peak. Focusing is generally considered bad, but if nobody sits there it might be okay. I put absorbers under the peak in my home recording studio room as shown below.
> 
> 
> --Ethan



Thanks - Mine is flat at the top, but has slopes on all four walls where the wall meets the ceiling. I guess you still call it vaulted. Not sure how it will affect reflection/focusing, will try to post a pic.


----------



## nathan_h




> Quote:
> Originally Posted by *gravi* /forum/post/18565972
> 
> 
> Thanks - Mine is flat at the top, but has slopes on all four walls where the wall meets the ceiling. I guess you still call it vaulted. Not sure how it will affect reflection/focusing, will try to post a pic.



The "mirror test" will help you find the first reflection points on your ceiling. Those spots and, even more so, where the ceiling meets the wall (for bass trapping) are the likely places you want to consider placing thick treatments.


----------



## ShockFett

I have a few questions I need help with.


1. For Mid/High what thickness of OC 703?

2. For LF what thickness of OC 703?

3.From what I understand a bass trap is anything in a corner and for mid/high is against flat wall correct?

4. What type of material/fabric is consider proper for making my own panels?

5. For the rear wall, how far away can I not worry about delayed reflections? I am 14 feet away from the back wall.

6. I plan on making a cloud will OC 703 work fine?


Thanks everyone for your help and suggestions. I really appreciate it.


----------



## Ethan Winer




> Quote:
> Originally Posted by *gravi* /forum/post/18565972
> 
> 
> Mine is flat at the top, but has slopes on all four walls where the wall meets the ceiling.



Wall-ceiling corners like that are also good candidate locations for bass traps.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *ShockFett* /forum/post/18567210
> 
> 
> 1. For Mid/High what thickness of OC 703?



Two inches is enough, but thicker can only help.



> Quote:
> 2. For LF what thickness of OC 703?



Four inches thick is good, but thicker is better.



> Quote:
> 3.From what I understand a bass trap is anything in a corner and for mid/high is against flat wall correct?



Well, almost. Bass exists at walls too.



> Quote:
> 5. For the rear wall, how far away can I not worry about delayed reflections? I am 14 feet away from the back wall.



When a rear wall is closer than ten feet away, reflections from that wall are considered "early" and are more damaging than when the wall is farther away.


--Ethan


----------



## Weasel9992




> Quote:
> Originally Posted by *ShockFett* /forum/post/18567210
> 
> 
> 4. What type of material/fabric is consider proper for making my own panels?



Burlap would be fine, but Guilford of Maine fabric is a great option. More expensive by a good bit than burlap, but much nicer and class-A fire rated. Tons of options here though.



> Quote:
> Originally Posted by *ShockFett* /forum/post/18567210
> 
> 
> 6. I plan on making a cloud will OC 703 work fine?



Yes. Whether you use 4" or 2" panels is the question.


Frank


----------



## Terry Montlick

Yes, clouds can be great. The rear surface can often function just as well as the front, giving you 2 times the absorption for the price of 1.


----------



## ShockFett

Thanks for all the help guys! I truly appreciate all of it.


I now have another question. Does anyone have a graph the shows the thickness of a panel and how it responds to the hz? I want to know at what frequency does each thickness absorb.


----------



## pepar




> Quote:
> Originally Posted by *ShockFett* /forum/post/18590074
> 
> 
> Does anyone have a graph the shows the thickness of a panel and how it responds to the hz?



Ask and ye shall receive .


----------



## ShockFett

Wow, thank you kind sir!


----------



## design1stcode2nd

For bass traps is there a specific size of triangle needed for it to be effective? I'm plotting out my screen wall which will have two columns for the L/R speakers. The interior width will only be 13"-14 wide with maybe 8"-10 of room behind the speaker itself to place a bass trap. Is it worth doing traps in such a small place?


I'll be placing linacoustic or similar below the screen which will house the center and sub(s) and should easily be able to do 2 worth there.


----------



## nathan_h

For those looking for OC703 in the SF Bay Area, I have just learned that MacArthur Co, in San Jose, on Las Plumas Ave (at 1670, behind some other businesses) close to the 101, sells the 1" and 2" sheets. They were willing to sell less than a full box (which I think is 24 sheets of the 1") for a little more than $4/sheet (including tax). This is the 1" 4feetx2feet stuff, unbacked.


I don't know how much they typically have in stock versus needing to order for you, but a quick phone call will tell you whether they have enough for a particular project. Note that while they are a commercial outfit, they didn't have any trouble/concern selling me the exact number of sheets I wanted, and charging my CC. They even helped stuff it into my car.


----------



## citizen arcane




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18576894
> 
> 
> 
> 
> Yes. Whether you use 4" or 2" panels is the question.
> 
> 
> Frank




For ceiling clouds - 2" panels spaced 2" from the ceiling ok?


----------



## Terry Montlick




> Quote:
> Originally Posted by *citizen arcane* /forum/post/18610561
> 
> 
> For ceiling clouds - 2" panels spaced 2" from the ceiling ok?



To be ceiling clouds, 2" spacing from the ceiling doesn't cut it. More like 2' is what you need. However, this should still create excellent wide-band absorption.


- Terry


----------



## Diesel 48

Hey everyone, it has been awhile since I have posted anything. But I recently found a local source for OC703, well an equivalent according to Bob's gold website and the spec sheet that came with the insulation. It is Johns manville Spin Glass board, at 3pcf in 2" and 4" thicknesses. Since I found a local source I decided to start building more acoustical panels.


When I first setup my room, I bought 4 real traps. As you can see in the pictures two are hanging in the front two corners, 1 is center on the front ceiling / wall corner and one is installed in the back of the room corner. I recently install 4" panels at my first reflection points this past weekend. My question is what should I do next?


My room is 94.25" tall, 152"W (as you can see in the picture there is a bump out that makes the half the wall 161"W) and 190"L (This same bump out is on the front wall so half of the wall is 199"L)


I was thinking of adding bass traps on the left and right ceiling corners, probably 2 per side. I think I can add 2 - panels to the left of my dvd/projector tower and then possible build a bass trap that I can place in the corner by the door when watching a movie. Should I add more panels on the side wall? What about the front wall? I appreciate all of your input! Let me know if you need anymore information.


----------



## TumaraBaap




> Quote:
> Originally Posted by *heavyflyr* /forum/post/18541958
> 
> 
> Umm no not at all. They protrude out from the cabinet and are not affected in any way.



I think Pepar is right. Speakers are usually directional at higher frequencies and increasingly radiate sound in all directions at lower frequencies, which is why placement in -or close proximity to- cabinets can color sound. From the pic the fit seems snug, but if there are any cavities it'd be advisable to fill them with fiberglass.


----------



## tkoden

Hey guys, I am in the middle of a remodel and have been thinking about some basic stuff to reduce sound. Is there anywhere that says exactly what the benefits of things like double sheetrock (with silicon in the middle) among other things do to reduce sound? I have quite a few windows (dual pane) but I am worried that the effort may be futile.


----------



## erkq




> Quote:
> Originally Posted by *tkoden* /forum/post/18668869
> 
> 
> Hey guys, I am in the middle of a remodel and have been thinking about some basic stuff to reduce sound. Is there anywhere that says exactly what the benefits of things like double sheetrock (with silicon in the middle) among other things do to reduce sound? I have quite a few windows (dual pane) but I am worried that the effort may be futile.



If you're going to put something in between 2 sheets of sheetrock, make it Green Glue. Even with windows you can sound-reduce to the rest of the house. Your neighbors may hear it though. But as pointed out above, you have to do a complete system, including boxing in electrical outlets and switches, soundproofing HVAC ducts, sealing doors, etc.


If it's a remodel you might consider something like Quietrock instead of Green Glue. Installation is 1/2 as hard. But again... it's got to be a complete job.


----------



## TumaraBaap




> Quote:
> Originally Posted by *tkoden* /forum/post/18668869
> 
> 
> Hey guys, I am in the middle of a remodel and have been thinking about some basic stuff to reduce sound.




Just keep in mind, in the event you succeed in reducing sound leakage from your listening room (and it is a daunting undertaking), you will compromise what you hear in that room.


Even the best sound systems struggle to achieve a flat sound power response. A good amplitude response usually means you have to shortchange power response in the higher frequencies. This is further worsened by the fact that it is easier to absorb higher frequencies than low frequencies. Gypsum walls that flex a bit are a godsend -- helping bass absorption. This energy sequestered within your listening room may cause not only boominess but bass unevenness with peaks and suckouts in different seats.


It sure is nice to have the rest of the home isolated from the battles raging in one's HT. But it is also one of the first nice-to-haves I'm willing to forfeit.


----------



## erkq




> Quote:
> Originally Posted by *TumaraBaap* /forum/post/18672811
> 
> 
> Gypsum walls that flex a bit are a godsend -- helping bass absorption. This energy sequestered within your listening room may cause not only boominess but bass unevenness with peaks and suckouts in different seats.



Keep in mind that Green Glue works by converting the vibration to heat. So the sound is not kept in the room by Green Glue either. I don't know how Quietrock works, though.


----------



## Terry Montlick




> Quote:
> Originally Posted by *erkq* /forum/post/18673181
> 
> 
> Keep in mind that Green Glue works by converting the vibration to heat. So the sound is not kept in the room by Green Glue either. I don't know how Quietrock works, though.



Green Glue converts some sound energy into heat. QuietRock works the same way -- it has a constrained layer damping layer in the middle.


- Terry


----------



## Weasel9992




> Quote:
> Originally Posted by *Diesel 48* /forum/post/18614962
> 
> 
> I was thinking of adding bass traps on the left and right ceiling corners, probably 2 per side. I think I can add 2 - panels to the left of my dvd/projector tower and then possible build a bass trap that I can place in the corner by the door when watching a movie. Should I add more panels on the side wall? What about the front wall? I appreciate all of your input! Let me know if you need anymore information.



I'm not sure where you'd put anything on the front wall...there's not much space left. As far as I can see the two biggest opportunities are the back wall (6" bass trap) and maybe the wall/ceiling trapping you're suggesting.


Frank


----------



## sbeveraggi

Hi guys, I want to improve my room acoustics, and desperately need some advice on what to buy and how to place it. Bass response is very uneven (lacks punch, but also shakes the room), and by clapping my hands I detect lots of echo. Music sounds a lot better listening from the adjacent room!!!


My current equipment is:

Denon AVR-2809ci with audyssey XT

Paradigm S2 v3 fronts

Rythmik F12SE sub (planning on getting a 2nd one)


I'm slowly but steadily building a dedicated room. My listening preferences are 70% music 30% HT.

My setup is 2.1, soon to be 2.2, then 4.2, and finally 5.2.

The room has wooden floors and no treatments whatsoever. Just heavy drapes for the window and a small carpet.


Good news is I can add as many ugly room treatments as I can afford ($500-$999), no WAF issues. Bad news is I prefer not to change the orientation of my gear, unless it is absolutely necessary. Is it?

Also, I would prefer the ready made route to DIY.


I was looking into the Auralex Project 2 Room Kit, is it good? I already own their subdude and speakerdudes and am happy with them.


Thanks in advance for your help!


----------



## Weasel9992

You're not going to love this advice, but yes...you'd be much better off firing down the longest dimension of the room. The difference between 17.5' and 10' is pretty massive. I think some foam could be part of the solution, but you'll need to do some basic bass trapping in there first. If you can't get into the vertical corners (and it looks like there aren't many to work with), there's always the wall/ceiling corners. I'd also get 4" panels up at the reflection points and on the front wall. Are you keeping the closet as-is in the back of the room?


Frank


----------



## sbeveraggi




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18688011
> 
> 
> You're not going to love this advice, but yes...you'd be much better off firing down the longest dimension of the room. The difference between 17.5' and 10' is pretty massive. I think some foam could be part of the solution, but you'll need to do some basic bass trapping in there first. If you can't get into the vertical corners (and it looks like there aren't many to work with), there's always the wall/ceiling corners. I'd also get 4" panels up at the reflection points and on the front wall. Are you keeping the closet as-is in the back of the room?
> 
> 
> Frank



Thanks for your advice Frank.

I guess I could move things around if it will result in a very audible improvement.

The thing is I will have the window behind one of the speakers (a bit above, though) and the closet (it has to stay) behind my listening position.

Which one is the lesser evil?


----------



## Weasel9992

I'd leave it behind the monitors so that the closet is to your back.


Frank


----------



## sbeveraggi




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18688884
> 
> 
> I'd leave it behind the monitors so that the closet is to your back.
> 
> 
> Frank



Thanks again Frank.

OK, that could work... facing the window, closet to my back. What distance should there be between the speakers and the window wall? How should I treat that wall? How should I treat the side walls? Ideally, how far from the back closet should the listening position be? How do I treat the closet wall? The angle between the closet wall and the ceiling is made of sheetrock, so I could place bass traps there... is that a good idea?


----------



## Weasel9992




> Quote:
> Originally Posted by *sbeveraggi* /forum/post/18690538
> 
> 
> What distance should there be between the speakers and the window wall? How should I treat that wall?



As much as you can get. Your head should be 38% of the way into the room from the front wall or 38% from the back wall (the front wall is a better). You'll have to figure out what the listening triangle is going to be and figure it out from there.



> Quote:
> Originally Posted by *sbeveraggi* /forum/post/18690538
> 
> 
> How should I treat the side walls?



I'd do 4" panels there.



> Quote:
> Originally Posted by *sbeveraggi* /forum/post/18690538
> 
> 
> Ideally, how far from the back closet should the listening position be?



Again, it all depends on the listening triangle and whether you're measuring it from the front wall or the back wall.



> Quote:
> Originally Posted by *sbeveraggi* /forum/post/18690538
> 
> 
> How do I treat the closet wall?



What kind of closet is it? Can you turn it into a bass trap or do you have to actually put stuff in it? You could always put up some thick bass trapping on stands in front of the closet doors.



> Quote:
> Originally Posted by *sbeveraggi* /forum/post/18690538
> 
> 
> The angle between the closet wall and the ceiling is made of sheetrock, so I could place bass traps there... is that a good idea?



Yes.


----------



## sbeveraggi




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18691134
> 
> 
> As much as you can get. Your head should be 38% of the way into the room from the front wall or 38% from the back wall (the front wall is a better). You'll have to figure out what the listening triangle is going to be and figure it out from there.
> 
> 
> 
> 
> I'd do 4" panels there.
> 
> 
> 
> 
> Again, it all depends on the listening triangle and whether you're measuring it from the front wall or the back wall.
> 
> 
> 
> 
> What kind of closet is it? Can you turn it into a bass trap or do you have to actually put stuff in it? You could always put up some thick bass trapping on stands in front of the closet doors.
> 
> 
> 
> 
> Yes.



The closet is full of clothes, but I think I may be able to put something like tri-traps on the room corners, inside the closet. Would that be OK? Or will the wood closet doors prevent the tri-traps from doing what they're supposed to do?

I was looking into your room kits... which one do you think will work best for my room?

Thanks again,

Santi


----------



## sathyakamaraj

*got the answer from DC...Going with 1" Linacoustic*

*Product**Thickness**Mounting**Density**125hz**250hz**500hz**1000hz**2000hz**4000hz**NRC**Size / Quantity**Price**Sq.Ft*703, plain1" (25mm)on wall3.0 pcf (48 kg/m3)0.110.280.680.90.930.960.7OC2'X4'X1"X48 Pieces*$236.00**384 Sq.ft*Linacoustic RC1" (25mm)0.080.310.640.840.971.030.7JM4'X100'X1"*$220.00**400 Sq.ft*
FRONT WALL









REAR WALL











Acoustic ( half @$$ Acoustic Plan - doing only 1" & not complete room)

1. Screen Wall Complete with the above material - and GOM ( or any other alternate Fabric - GOM is expensive )

2. Side Walls & Real Walls - 30" height from bottom of the room - throughout the room

3. After complete setup if there is any issue with too much reflection (ofcoz there will be)- I will work on Fabric Frames..If not just paint and wood work...

*Questions:*

1. OC or Linacoustic ( Price is almost same )

Interms of performance both looks pretty same -

2. OC or Linacoustic

Interms of installation : I feel that Linacoustic will be easy to cut and can run long in length. And also less itchy (i dont know)


Help me out !


----------



## video_bit_bucket

I am trying some on walls, Paradigm W5's, behind my AT screen. The center has a slight hollow sound to it which I have not had with the floor standing speakers in the same space in the past. I can not imagine this is what these normally sound like and suspect the wall construction. This is a very thin faux wood panel with concrete block behind it with a 1 7/8 inch empty cavity between the two. I really do not want to pull the speakers out on a stand presuming that they are designed to work with a more solid boundary. Opinions?


----------



## HaleMoana

**EDIT**


Never mind.


----------



## noah katz

I know that the effectiveness of a given amount of fiberglass is improved if there's airspace behind it, but is it even better to fill that space with more fiberglass?


The airspace deep enough to give 1/4-wave reflection cancellation, so I'm guessing it's the latter, and maybe even the former.


----------



## Terry Montlick

No simple answer. For fiberglass of reasonable density and low frequencies, the answer is that it's marginally better to fill the space. For high acoustic resistance stuff like heavy mineral wool and/or higher frequencies, not filling the space can be preferable.


----------



## noah katz

OK, thanks, Terry.


----------



## whitewolf1

Terry,

I appreciate the tools available on your site and I have a question reference the room calculator. My room will have 9' ceilings across the top 7 feet of width then angle down to a kneewall around 4 1/2 feet to 5 1/2 feet high. The width of the room will be 14 to 16 feet wide at floor to kneewall height (4 1/2-5 1/2') then angle up to the 9 foot ceiling height. How would the calculator be used in this instance? Calculate averages or because of the additional angles of reflections are the calculators useless?


I am building my theater on Cape Cod and was looking to use your services and was not happy to find out you were not taking on new clients. Anyway you provided some helpful advice in my previous venture in NH and I appreciate it. I did get the BFD1124 and equipment you mentioned before but had trouble getting the measurement software to play properly and never really tested my room as planned. I was still happy with the theater but am back to do it better. The room may not be optimal but still should work out.Thanks!


----------



## SierraMikeBravo

Hi whitewolf,


Predicting rooms that are not uniformly rectangular become very difficult. It can be done to some extent, and it involves very complicated mathematics. The best approach is to either make your room rectangular through construction or, make an assumption that your room is rectangular to use the calculator. However, it will not be optimal and there will likely be additional modes that appear in the analysis that were not predicted in the model. If your room is "close" to rectangular, it should behave "nearly" as such. If not, all bets are off! Best wishes!


----------



## Dennis Erskine

To augment SMB's post above, what you can do to approximate the results using the standard tools you have available, for the height of the room use the average height and average width. You've got a lot of angles to deal with. Good luck...it's not easy!


----------



## whitewolf1

Thanks Dennis and SMB!

I will not have a rectangular room and if I did so would end up with a 5 ft ceiling. I, too, was thinking of averaging and going from there. That being said should I bother with trying to set a width that supposedly has good demensions or make it as wide as possible to comfortably seat 4. I currently have framed kneewalls with a 13'11" width and 5'7" height. I would like to go to 15-16' wide for seating. I have 21' length so one row likely with a bar/benched format to fit stools for certain occasions.


----------



## pepar




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18770717
> 
> 
> Thanks Dennis and SMB!
> 
> I will not have a rectangular room and if I did so would end up with a 5 ft ceiling. I, too, was thinking of averaging and going from there. That being said should I bother with trying to set a width that supposedly has good dimensions or make it as wide as possible to comfortably seat 4. I currently have framed kneewalls with a 13'11" width and 5'7" height. I would like to go to 15-16' wide for seating. I have 21' length so one row likely with a bar/benched format to fit stools for certain occasions.



I built my house 20 years ago with a "media room" and the bright idea that I'd have no parallel surfaces and therefore no slap echo and no room modes. Success on the former, but absolutely no joy on the second. My ceiling, left and rear walls are splayed by 1° and just beyond eliminating slap echo is the fact that _there are no room mode calculators that model my room_.


Having said that, acoustical treatments are your friend. Short of avoiding dimensions that are multiples (or even fractions) of themselves, build your room as you need to to accomplish your design goals wrt seating and amenities and then be prepared to spend money on acoustical treatments. Do NOT scrimp on acoustical treatments.


To know what to put where, either familiarize yourself with REW acoustical measuring software and acoustics or pay a pro to tell you what to put where.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18770717
> 
> 
> Thanks Dennis and SMB!
> 
> I will not have a rectangular room and if I did so would end up with a 5 ft ceiling. I, too, was thinking of averaging and going from there. That being said should I bother with trying to set a width that supposedly has good demensions or make it as wide as possible to comfortably seat 4. I currently have framed kneewalls with a 13'11" width and 5'7" height. I would like to go to 15-16' wide for seating. I have 21' length so one row likely with a bar/benched format to fit stools for certain occasions.




Width is your friend!


----------



## whitewolf1

You confirm my feelings on the matter. Thanks for the input. I am in touch with a pro that should be able to help me with acoustic treatment. I am afraid of the financial pain that will bring but what can you do. Thanks fore the input on width SMB. My room will have issues so might as well get good physical use of it. Thanks guys!


----------



## jasplat88

Hi everyone. It's been awhile since I've been in this forum (built my 1st theater in 2003/4) and didn't get around to building the last theater Dennis designed for me in late '07 (due to a move). However, I did purchase a new home that has a theater, and I am looking for some suggestions on how and where to apply acoustical treatments to this room. The theater is 17' x 22' (although the screen is recessed another 15"). The wall starts the 45 degree at 4' and the celing height is 9'8".










Front of Theater










Rear of Theater


Suggestions?


----------



## nathan_h

Bring the L+R out of those coves, and consider a few thick panels on the ceiling (mirror method) and test whether the side wall panels are really in the right spots (mirror method). Consider some bass traps saddling the rear corners and the rear wall/ceiling junction.


----------



## whitewolf1

Wow! Those demensions and basic design is almost identical to my situation. It looks sharp but the acoustics are my concern. How bad is it before the necessary treatments and has anybody attempted to treat it? I am wondering if its worth it to venture into the project at all if it is too costly to fix and will look like a pin cushion when your done. It would be a shame to reck the look of that room!


----------



## pepar




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18773247
> 
> 
> Wow! Those demensions and basic design is almost identical to my situation. It looks sharp but the acoustics are my concern. How bad is it before the necessary treatments and has anybody attempted to treat it? I am wondering if its worth it to venture into the project at all if it is too costly to fix and will look like a pin cushion when your done. It would be a shame to reck the look of that room!



Some pincushions are more attractive than others.


----------



## Terry Montlick

Treat both knee walls and angled walls with panels and perhaps diffusers as well. Treatment details (area, depth, etc.) for a target reverberation time depend on your particular room and its characteristics.


----------



## whitewolf1

Terry,


Can a room like the one above be made to sound well with treatment or is adequate all that can be expected? Also, if yes, will the nice aesthetic look the room now has look very different and maybe not so nice?


----------



## Terry Montlick




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18773549
> 
> 
> Terry,
> 
> 
> Can a room like the one above be made to sound well with treatment or is adequate all that can be expected? Also, if yes, will the nice aesthetic look the room now has look very different and maybe not so nice?



It can be made to sound excellent, without question. Aesthetics-wise, it can look great if you spend adequate time and/or money. It essentially requires be building out of new surfaces for acoustic treatment. These cost 1"-2" plus in depth for each such surface.


----------



## jasplat88




> Quote:
> Originally Posted by *nathan_h* /forum/post/18772232
> 
> 
> Bring the L+R out of those coves, and consider a few thick panels on the ceiling (mirror method) and test whether the side wall panels are really in the right spots (mirror method). Consider some bass traps saddling the rear corners and the rear wall/ceiling junction.



The coves would not have been in my ideal design either, but short of rebuilding the front wall (which I may do at some point) I am stuck with them. I did know this going into my speaker purchase and purchased AT6200e's which allow for boundary compensation, and supprisingly this theater (to my ear) sounds much better than my last theater which was treated for first reflection points and bass traps. I think that's why I am wanting to understand if it could sound better and how to go about that without significantly changing the theater.


-Jason


----------



## jasplat88




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18773247
> 
> 
> How bad is it before the necessary treatments and has anybody attempted to treat it?



I would not define the acoustics as *bad* at all, but I am not looking at a real-time computer generated graph which would tell the technical "truth". I am just looking for ideas on how and where to try/test based on the room design.


The tweeters of the L/R's are right at the same height of where the detailed trim casing is for the side walls which made me believe they are already being defused in a way and treating below would be unnecessary and above is angled and would likely only have a small area where 1st reflections would occur.


Does anyone have photos or examples (link) of an angled wall similar to mine that have been treated? I'm curious if it's been done in a creative/artistic way where the entire wall was not treated, but accomplished the neccesary treatment. Thanks!


-Jason


----------



## whitewolf1

Jasplat its nice to know it at least sounds good to you. Is there treatment behind the fabric(or is it fabric and if so what is it?) on the walls? Soundproofing? Bas traps? It looks great and leaves me more encouraged since I'm stuck with that design or go without.


----------



## nathan_h




> Quote:
> Originally Posted by *jasplat88* /forum/post/18773892
> 
> 
> The coves would not have been in my ideal design either, but short of rebuilding the front wall (which I may do at some point) I am stuck with them.



Sure, you are stuck with the coves -- but you don't have to put the speakers in them.



> Quote:
> Originally Posted by *jasplat88* /forum/post/18773953
> 
> 
> The tweeters of the L/R's are right at the same height of where the detailed trim casing is for the side walls...



...which may be irrelevant, if your ears are higher than the tweeters. But 10 minutes with a friend/spouse/child/neighbor/drinking buddy holding a mirror on the angled ceiling/wall will tell you whether there is an issue. Remember, if you can see the speaker in the mirror while you are seated at your main seating location, and there isn't a thick panel there already, that is a place to add a thick panel -- whether on the ceiling, side wall, angled wall, back wall, front wall. (The converse is true, too: If you have panels in places that are NOT first reflection points, and they are not super thick bass trapping panels, you may want to consider moving them to real first reflection points where they will do more good/less damage.)


In addition to the mirror trick, measures are your friend.


----------



## whitewolf1

Terry,


If you had to guess, and the walls were bare, what would be your initial approach toward treatment without knowing specifics? EG: 2" absorption kneewall at first reflection and angled ceiling first reflection, Absorption or diffision in rear first reflection and base traps in corner. I realize measurements would be necessary to fine tune but I am thinking of trying initial treatments and bring in someone with knowhow to improve it. Thanks!


----------



## nathan_h




> Quote:
> Originally Posted by *jasplat88* /forum/post/18773892
> 
> 
> The coves would not have been in my ideal design either, but short of rebuilding the front wall (which I may do at some point) I am stuck with them.



Sure, you are stuck with the coves -- but you don't have to put the speakers in them.



> Quote:
> Originally Posted by *jasplat88* /forum/post/18773953
> 
> 
> The tweeters of the L/R's are right at the same height of where the detailed trim casing is for the side walls...



...which may be irrelevant, if your ears are higher than the tweeters (for example). IE, from the picture, I'd guess that they may all be too low for catching the side wall first reflection points for the front row, and they are definitely too low for the second row (unless the picture is really not capturing the geometry well).


But 10 minutes with a friend/spouse/child/neighbor/drinking buddy holding a mirror on the angled ceiling/wall will tell you whether there is an issue. Remember, if you can see the speaker in the mirror while you are seated at your main seating location, and there isn't a thick panel there already, that is a place to add a thick panel -- whether on the ceiling, side wall, angled wall, back wall, front wall. (The converse is true, too: If you have panels in places that are NOT first reflection points, and they are not super thick bass trapping panels, you may want to consider moving them to real first reflection points where they will do more good/less damage.)


In addition to the mirror trick, measurements are your friend.



> Quote:
> Originally Posted by *jasplat88* /forum/post/18773892
> 
> 
> surprisingly this theater (to my ear) sounds much better than my last theater which was treated for first reflection points and bass traps.



Ultimately, this is what it comes down to.


I don't know what the last theater was setup like, so whether treating the first reflection points caused your dissatisfaction (relative to the new theater) or whether they ameliorated what would have been a more unpleasant (relative to the new theater or what the old theater actually sounded like) situation is tough to guess.


Certainly, some people prefer few side wall first reflection point treatments. (This is one of those controversial topics covered in Toole's infamous book -- though even he said it's not a black and white preference for all listeners, and he still recommended first reflection point panels on the front and back wall, even when he wasn't an advocate of side-wall panels.)


----------



## whitewolf1

Nathan,


Are you talking the center speaker or any of the 3 L/C/R speakers? I would think the mirror would show for almost the whole front in that case. Wouldn't it? Not saying I know, just visualizing in my head.


----------



## pepar

I'd look at an acoustically transparent screen and place the speakers behind it. That would both allow a bigger screen as well as get the L&R out of cove.


Jeff


----------



## jasplat88




> Quote:
> Originally Posted by *pepar* /forum/post/18774349
> 
> 
> I'd look at an acoustically transparent screen and place the speakers behind it. That would both allow a bigger screen as well as get the L&R out of cove.
> 
> 
> Jeff



Ideally Jeff this is what I would like to do. I just don't have the budget for it now. The theater Dennis designed for me has a similar front wall design to what I would like to do in this room at some point in the future. Tear out that front wall, add a bigger motorized AT screen, put the speakers behind it, which would also allow me to add a flat screen on that wall too, and remove any coves. Then I could treat the entire front wall and go from there.


One of my challenges is that the side walls are tight to the seating platform (which is 12' wide) and for those not vertically challenged (6' +) you have to be careful not to bop your head on the sloped wall when entering and exiting the theater. Adding another inch or so in treatment would exagerate that issue. That's why I was wondering if there is a way to artistically treat in some sort of pattern sections of the angled walls (to cover the 1st reflections, but minimize the covering to the *needed* areas only) and still have the room look good.


-Jason


----------



## nathan_h




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18774329
> 
> 
> Nathan,
> 
> 
> Are you talking the center speaker or any of the 3 L/C/R speakers? I would think the mirror would show for almost the whole front in that case. Wouldn't it? Not saying I know, just visualizing in my head.



Yes one might end up with a band a foot or two tall across much of the front. Of course, existing screen placement may mean one cannot really treat everywhere the mirror says. Nothing is perfect and I'd choose to be able to see the screen rather than cover part of it with panels











> Quote:
> Originally Posted by *pepar* /forum/post/18774349
> 
> 
> I'd look at an acoustically transparent screen and place the speakers behind it. That would both allow a bigger screen as well as get the L&R out of cove.



That's a REALLY GOOD idea to explore, if the budget for a new screen exists.


----------



## jasplat88




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18774240
> 
> 
> Jasplat its nice to know it at least sounds good to you. Is there treatment behind the fabric(or is it fabric and if so what is it?) on the walls? Soundproofing? Bas traps? It looks great and leaves me more encouraged since I'm stuck with that design or go without.



The only *treatment* in the theater is the zebra carpet (not my choice) and the Berklines....so no, no treatments. That's why I am wanting to experiment with adding some, as it did improve my last theater's acoustics and I'm sure it can improve this theaters too.


----------



## jasplat88




> Quote:
> Originally Posted by *nathan_h* /forum/post/18774264
> 
> 
> Sure, you are stuck with the coves -- but you don't have to put the speakers in them.
> 
> 
> 
> 
> ...which may be irrelevant, if your ears are higher than the tweeters. But 10 minutes with a friend/spouse/child/neighbor/drinking buddy holding a mirror on the angled ceiling/wall will tell you whether there is an issue. Remember, if you can see the speaker in the mirror while you are seated at your main seating location, and there isn't a thick panel there already, that is a place to add a thick panel -- whether on the ceiling, side wall, angled wall, back wall, front wall. (The converse is true, too: If you have panels in places that are NOT first reflection points, and they are not super thick bass trapping panels, you may want to consider moving them to real first reflection points where they will do more good/less damage.)
> 
> 
> In addition to the mirror trick, measures are your friend.




Yep, I used the mirror in my last theater to find FRP's..just hadn't done it in this one. You're right, it's cheap and could be quite telling. Thanks!


-Jason


----------



## pepar




> Quote:
> Originally Posted by *jasplat88* /forum/post/18774489
> 
> 
> One of my challenges ...


----------



## whitewolf1

Thanks for the info Jasplat. I have an AT screen and will build mine accordingly. I wasn't too keen on the zebra look either but the rest looks nice even though varying from textbook. I think treatments where your thinking about may unfortunately be necessary for the both of us. Good luck!


----------



## jasplat88




> Quote:
> Originally Posted by *whitewolf1* /forum/post/18776766
> 
> 
> Thanks for the info Jasplat. I have an AT screen and will build mine accordingly. I wasn't too keen on the zebra look either but the rest looks nice even though varying from textbook. I think treatments where your thinking about may unfortunately be necessary for the both of us. Good luck!



After doing the mirror test tonight, I am developing a plan which I think will be a good compromise between acoustic improvement and keeping within the design of the theater. I'll let it be a supprise and post photos when I get it done (I'll be ordering supplies tomorrow). Of course, I won't know exactly what improvement it will make until I take some measurements which I also plan to do, but if nothing else I should benefit from the placebo effect.


BTW, the side walls only had very small areas where there were first reflection points. The ceiling and back wall will benefit from some treatments as well.


The zebra carpet we inherited with the theater has grown on me, the wife hates it. It's not worth the $750-1000 it would cost me to replace....so it's staying. Keep us posted on your theater's progress. Best of luck!


----------



## whitewolf1




> Quote:
> Originally Posted by *jasplat88* /forum/post/18777536
> 
> 
> After doing the mirror test tonight, I am developing a plan which I think will be a good compromise between acoustic improvement and keeping within the design of the theater. I'll let it be a supprise and post photos when I get it done (I'll be ordering supplies tomorrow). Of course, I won't know exactly what improvement it will make until I take some measurements which I also plan to do, but if nothing else I should benefit from the placebo effect.
> 
> 
> BTW, the side walls only had very small areas where there were first reflection points. The ceiling and back wall will benefit from some treatments as well.
> 
> 
> The zebra carpet we inherited with the theater has grown on me, the wife hates it. It's not worth the $750-1000 it would cost me to replace....so it's staying. Keep us posted on your theater's progress. Best of luck!



I'll keep you posted! I am looking into the details of design presently and the view of your theater really helps.


Also, How do the side surrounds perform? I noticed their inwalls and appear to angle downward. I have larger ribbon direct speakers from soundsalk and will probably bracket them partially inwall facing straight over the head. Thats my thought at the moment anyway. They are a problem for me but I'm sticking with them and will need to compromise aesthetics for their placement.


I am looking forward toward seeing the results of your acoustic efforts. Good luck and I'll keep my fingers crossed!


----------



## Dan Hitchman

In the plan I'm having to deal with, there is a one-foot deep acoustically transparent false wall along the front where I could place some corner bass traps. Since they don't have to be triangular (as they'd be hidden from view), would it be best to use two 2' wide by 6" deep OC703 (2" thick) square "pillars"?


I could probably do regular 17x17x24" triangular "chunk" traps in the back corners. I need some "aesthetic value" there.


I have 10' high ceilings in the plan I'm dealing with.


Any other suggestions than that? Thx.


----------



## Vaggeto

I searched and couldn't find anything on this which suprises me, but did anyone else notice a relatively strong smell from their linacoustic? Mine smells almost fishy and is really quite strong in the basement and in the garage where the roll is.


It wasn't very noticeable while in the plastic bag unless up close, but is now that it is open and exposed to the air.


----------



## Dennis Erskine




> Quote:
> that is a place to add a thick panel



Let's not go over the top absorbing everthing...diffusion is more likely required. What speakers you using?


Absorption is not the solution to every problem and is over used and over used.


----------



## macboy




> Quote:
> Originally Posted by *Vaggeto* /forum/post/18793430
> 
> 
> I searched and couldn't find anything on this which suprises me, but did anyone else notice a relatively strong smell from their linacoustic? Mine smells almost fishy and is really quite strong in the basement and in the garage where the roll is.
> 
> 
> It wasn't very noticeable while in the plastic bag unless up close, but is now that it is open and exposed to the air.



My roll does not have any smell. I really don't think it should smell; it is intended to be installed inside air ducts after all. Maybe you got a bad batch? I would contact Johns Manville.


----------



## Dennis Erskine

It is possible you'll have a smell ... it's put in plastic at the factory and hasn't had time to air out. It will be fine in a few days.


----------



## pepar




> Quote:
> Originally Posted by *Vaggeto* /forum/post/18793430
> 
> 
> I searched and couldn't find anything on this which suprises me, but did anyone else notice a relatively strong smell from their linacoustic? Mine smells almost fishy and is really quite strong in the basement and in the garage where the roll is.
> 
> 
> It wasn't very noticeable while in the plastic bag unless up close, but is now that it is open and exposed to the air.



No smell here. Sounds like yours sat in a damp environment and developed mold. Not good. I'd spray it with something to kill the mold. Mold in the home can be a health hazard.


----------



## KNKKNK




> Quote:
> Originally Posted by *Vaggeto* /forum/post/18793430
> 
> 
> I searched and couldn't find anything on this which suprises me, but did anyone else notice a relatively strong smell from their linacoustic? Mine smells almost fishy and is really quite strong in the basement and in the garage where the roll is.
> 
> 
> It wasn't very noticeable while in the plastic bag unless up close, but is now that it is open and exposed to the air.



I cant speak to linacoustic but when I opened the 703 it had a strong ammonia like smell that dissipated after a few days.. I've seen others comment on similar experiences.


The odor is most likely the binder used that was not completely baked off/cured in the manufacturing process, the remainder is outgassing and producing the smell and should dissipate over time.


----------



## Vaggeto




> Quote:
> Originally Posted by *sathyakamaraj* /forum/post/18700460
> 
> *got the answer from DC...Going with 1" Linacoustic*
> 
> *Product**Thickness**Mounting**Density**125hz**250hz**500hz**1000hz**2000hz**4000hz**NRC**Size / Quantity**Price**Sq.Ft*703, plain1" (25mm)on wall3.0 pcf (48 kg/m3)0.110.280.680.90.930.960.7OC2'X4'X1"X48 Pieces*$236.00**384 Sq.ft*Linacoustic RC1" (25mm)0.080.310.640.840.971.030.7JM4'X100'X1"*$220.00**400 Sq.ft*
> 
> 
> Acoustic ( half @$$ Acoustic Plan - doing only 1" & not complete room)
> 
> 1. Screen Wall Complete with the above material - and GOM ( or any other alternate Fabric - GOM is expensive )
> 
> 2. Side Walls & Real Walls - 30" height from bottom of the room - throughout the room
> 
> 3. After complete setup if there is any issue with too much reflection (ofcoz there will be)- I will work on Fabric Frames..If not just paint and wood work...
> 
> *Questions:*
> 
> 1. OC or Linacoustic ( Price is almost same )
> 
> Interms of performance both looks pretty same -
> 
> 2. OC or Linacoustic
> 
> Interms of installation : I feel that Linacoustic will be easy to cut and can run long in length. And also less itchy (i dont know)
> 
> 
> Help me out !



I believe the Linacoustic is 1.5lb pcf and the OC is 3lb pcf so I would assume the have different absorbtion properties for sound.


I will have some leftover Linacoustic and wanted to create some corner"super chunk" bass traps with it but I'm not sure if it will work very well compared to OC703 or OC705.


Does anyone have any comments regarding this?


----------



## Doc Pete

So i havn't read all 300+ pages. I'm in the middle of building my theater in the basement. Here's the general stats


Room Size: 15' front wall, 27' side walls, 9' high

sitting distance 10'/16'/19' (table)


my question is, since i'm about to finish up framing: instead of hanging the sound absorbers/diffusers or what ever the owen corning 703 with fabric around it is, can i build them into the wall so they are flush with the drywall?


I would prefer to have a cleaner look


thanks

pete


----------



## Dennis Erskine

Nope ... not if you want any form of sound isolation at all. But...there is a way.


----------



## Doc Pete




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18806798
> 
> 
> But...there is a way.



Hmmm...very cryptic. What is that way?


----------



## pepar




> Quote:
> Originally Posted by *Doc Pete* /forum/post/18807008
> 
> 
> Hmmm...very cryptic. What is that way?



Room within a room.


----------



## Dennis Erskine

No, not room within a room. Sorry I can't be more specific.


----------



## erkq




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18807149
> 
> 
> No, not room within a room. Sorry I can't be more specific.



Can you tell us WHEN you can be more specific?


----------



## Vaggeto




> Quote:
> Originally Posted by *Doc Pete* /forum/post/18807008
> 
> 
> Hmmm...very cryptic. What is that way?



Please take note he said not with sound isolation because the lack of the drywall would allow sound to travel out of the room much easier.


I believe they would still help improve the SQ of the room, but would only absorb from the front rather than the front and sides. So less overall impact.


----------



## Dennis Erskine

There are various techniques, tricks, methods, we've developed over the years which we would prefer to keep proprietary. Many of those have to do with how we get the treatments installed without looking like we have treatments installed. I do believe, however, I've posted enough "in the rough" photos for it to be sorted out by a clever lad.


----------



## johnbomb




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18806798
> 
> 
> Nope ... not if you want any form of sound isolation at all. But...there is a way.



I can't speak for Dennis, but I had an idea (I haven't tested it, so use at your own risk):


If you strip your ceiling or wall down to nothing but studs (or joists) and the drywall behind the studs (or floor above the joists), you could drywall the inside of that cavity, perhaps decoupling that new drywall w/ standoff clips or strips. Then, you could fill in the newly drywalled, slightly reduced in volume cavity w/ whatever fiberglass or other treatment you want, and then cover the whole thing w/ GOM or equivalent.


It's a lot of work, but I might give it a shot, as I currently have everything exposed in my theater room.


John


----------



## pepar




> Quote:
> Originally Posted by *johnbomb* /forum/post/18810722
> 
> 
> I can't speak for Dennis, but I had an idea (I haven't tested it, so use at your own risk):
> 
> 
> If you strip your ceiling or wall down to nothing but studs (or joists) and the drywall behind the studs (or floor above the joists), you could drywall the inside of that cavity, perhaps decoupling that new drywall w/ standoff clips or strips. Then, you could fill in the newly drywalled, slightly reduced in volume cavity w/ whatever fiberglass or other treatment you want, and then cover the whole thing w/ GOM or equivalent.
> 
> 
> It's a lot of work, but I might give it a shot, as I currently have everything exposed in my theater room.
> 
> 
> John



This has me scratching my head. Doc Pete never mentioned anything about needing acoustical isolation, only acoustical treatments. If he doesn't care about isolation, he most certainly can build treatments flushed into the walls. And, if he has the space and if the walls are already constructed to the point where redoing them is too much of a pain, it _can_ be done as a room within a room, i.e. mount the treatments, install studs/furring strips and cover the entire area with an acoustically transparent material


----------



## kca48

Some interesting stuff posted here, will look into some of this in the future.


----------



## Weasel9992




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18807637
> 
> 
> There are various techniques, tricks, methods, we've developed over the years which we would prefer to keep proprietary. Many of those have to do with how we get the treatments installed without looking like we have treatments installed. I do believe, however, I've posted enough "in the rough" photos for it to be sorted out by a clever lad.













Frank


----------



## pepar




----------



## Doc Pete

So i don't know the proper terminology, but now that i think about it the panels i wanted to place flush with the drywall would be used for diffusing early reflection (i think diffusing is taking the source sound and when it hits the material it scatters it in multiple directions).

So i understand why Dennis wouldn't want to give away all his tricks since that's how he makes money... i understand that as a professional myself.

But i think to used my idea i would need to drywall a "slot" or recessed area for the diffuser to sit into. That is to block out sound from traveling through the diffuser to the next room and vice-versa.

I'm trying to do what acoustic work that i can do/understand/afford. I"m not able to be as through as i would like. I'm afraid of spending that much money trying and overlooking some small hole where the sound will still be able to communicate to an ajoining room and have it leak like a hole in a boat.


Pete


----------



## Dennis Erskine

Diffusors ... different animal. You can get a diffusor (Perf-Sorber from Questai.com) which is 2"; but, beyond that most diffusors need to be on the order of 4" deep to be worth anything.


----------



## Doc Pete

I just did some research looking for jobs you worked on and found that stuff and how you did it or at least kinda how you did it. (very cool ceiling by the way).


pete


ps this is for another thread but i think i have figured out the trade secret for anamorphic lens using cylinders and not prisms...


seems like all the things i try to find out are usually things you need to pay for...imagine that. hehe


----------



## FuzzyZipperbaum

Will painting 703 on the back wall change the absorption factors?


----------



## SierraMikeBravo

It all depends on how much paint you use, but yes, it generally will change the absorption factor for certain frequencies. Best wishes!


----------



## Vaggeto

I made a new thread for advice on my current build, I'd appreciate any input from everyone!

http://www.avsforum.com/avs-vb/showthread.php?t=1258508


----------



## Weasel9992




> Quote:
> Originally Posted by *FuzzyZipperbaum* /forum/post/18818039
> 
> 
> Will painting 703 on the back wall change the absorption factors?



Yes. It's not going to alter anything in terms of the low frequency response, but it'll make them much more reflective. If they're 2" panels then you'll pretty much be defeating their purpose.


Frank


----------



## johnbomb

It occurred to me that perhaps we should tailor our room treatment strategies to suit the individual channels in our theaters. I would very much appreciate expert opinion on my proposal below:


1) *center channel:* treat all early reflection points with absorption to cover the average frequency range of speech (low point around 85 hz?)- basically everything above crossover range. The idea is to create a "reflection free zone" at each seat to maximize speech intelligibility.


2) *fronts and surrounds:* treatment aimed at maximizing spaciousness, whether that means no treatment, diffusion, or judicious use of absorption, depending on room dimensions and construction.


Obviously, room layout can complicate this strategy. Depending on speaker position, the early reflection points of the center vs. the sides/surrounds may lie close enough to one another to render this strategy moot. Furthermore, one could argue that the effects of intelligent surround processing far outweigh room effects, and that such a strategy is overly complicated- why not just absorb everything, and let the computer do the work?


Feedback greatly appreciated.


Thanks,

John


----------



## Terry Montlick

Sorry to be blunt, but such a strategy doesn't work. Most of the sound we hear is reflected and of reflection order greater than 1. And it can come from almost anywhere, as ray-tracing simulation clearly shows.


----------



## Dennis Erskine

I'm afraid you 'll be very frustrated. While it will create a timbral imbalance in your room, you'll also find the L/R reflection points to various seats overlap the center channel reflection points.


----------



## johnbomb

Thanks, guys, that's immensely helpful to me.


John


----------



## Johnnycloud

Is it true that I only need 2 inch thick treatment for first reflection points? Basically, I am asking if it is better then putting a bass trap 4 or 6 inch treatment here. From what I have read and observed it seems 4 or 6 inches for corners for bass, and 2 inch thick for first reflection points. Am I on the right track?


----------



## nathan_h

If you can fit it, thicker is better at first reflection points too: more even broad frequency band absorption.


----------



## SierraMikeBravo

Personally, I feel that 2 inches should be adequate. Most of the problems associated with side reflections revolve around the speech frequency range IMHO. Some male voices can go lower than 250 Hz, but generally, we are dealing with frequencies above 200 Hz. We are not necessarily trying to kill the reflection, just dampen it enough so that it does not interact destructively with the direct wave. However, unless your speakers have a poor off axis response, killing the high frequencies, which is quite easy to do, will reduce your sound stage significantly. It has been suggested before to use more of an abfusor type treatment at certain points along the side walls such as RPG BAD panel or Quest Perf-sorber. Best wishes!


----------



## pepar

Does anybody know if there are any 3rd party comparisons of the various diffusors on the market? Prices are all over the place and I'm not 100% sure that the manufacturer-supplied data is apple-to-apples.


And if somebody has some proprietary information, I'd consider _buying_ it if it's not too expensive. PM me on this, and I'd sign an NDA.


Jeff


----------



## Weasel9992




> Quote:
> Originally Posted by *nathan_h* /forum/post/18830931
> 
> 
> If you can fit it, thicker is better at first reflection points too: more even broad frequency band absorption.



+1. I agree in most cases.


Frank


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/18836936
> 
> 
> Does anybody know if there are any 3rd party comparisons of the various diffusors on the market? Prices are all over the place and I'm not 100% sure that the manufacturer-supplied data is apple-to-apples.
> 
> 
> And if somebody has some proprietary information, I'd consider _buying_ it if it's not too expensive. PM me on this, and I'd sign an NDA.
> 
> 
> Jeff




Jeff,


I have heard both, and both sound slighly different based on construction methods. However, my personal preference is the Quest perf-sorber. It is much more versatile, and can be used in a variety of applications. And yes, the stuff is expensive. Can't have R&D and interesting assembly methods for cheap prices. However, if the perfsorber is bought raw and uncut, it's a little cheaper...but don't expect a give away of the farm. Often, nothing worth it ever really is. I plan to use a LOT of it in my current design of my room. Best wishes!


----------



## johnbomb

I have a question regarding a primitive root diffuser build that I plan, based on this link:

http://www.oliverprime.com/prd.php 


Can I generate a solution based on a single prime number and then break the grid up into pieces, to be placed at various locations on my back wall? I read somewhere that the George Massenberg designed Blackbird studio C utilized one single prime number for its primitive root design, and obviously, the MDF rods are all over the room. What ways can one go about distributing a single prime number based grid of rods around a room and not ruin the diffusive properties of the solution?


Thanks,

John


----------



## Terry Montlick

You can't break up an array of number theory diffuser wells and expect this to perform as a diffuser. The functioning of such a diffuser relies on having wells which are supposed to be adjacent actually being adjacent.


----------



## Elill




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18837521
> 
> 
> However, if the perfsorber is bought raw and uncut, it's a little cheaper..



SMB - quick question, when you say "raw" does that mean you can just get the panel face and install that over "stuff" (insulation) you've sourced elsewhere? Or is it the complete panel, just uncovered/finished with fabric?



> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18837521
> 
> 
> I plan to use a LOT of it in my current design of my room



I see RPG recommend you basically cover a room in this stuff, well hang panels covering quite a lot of area at any rate. They also seem to hang then in corners as bass traps?


I suppose what I am getting at is can you over do it with this stuff? I assume you wouldn't want an entire room covered in it


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/18879834
> 
> 
> I have a question regarding a primitive root diffuser build that I plan, based on this link:
> 
> http://www.oliverprime.com/prd.php
> 
> 
> Can I generate a solution based on a single prime number and then break the grid up into pieces, to be placed at various locations on my back wall? I read somewhere that the George Massenberg designed Blackbird studio C utilized one single prime number for its primitive root design, and obviously, the MDF rods are all over the room. What ways can one go about distributing a single prime number based grid of rods around a room and not ruin the diffusive properties of the solution?
> 
> 
> Thanks,
> 
> John




Hi John,

Nice to see someone else using the excellent "oliverprime" calculator for DIY skyline diffusers. I've built several so hopfully my experience will be of some value.


If you want to place several - let's call them Skylines for now - diffusers on your back wall, and wish to have them spread out, then you will need to build//buy each some seperately. You can use the same prime number each time for each Skyline but it's not a good idea. The general idea is that diffusion is best performed with less periodicity; pick one large enough prime number to cover all the intended wall area so as to avoid repetition. In other words, it's best to have 1 large Skyline than 2 or more that cover the equivalent wall space. If you still wish to place several Skylines spaced around the back wall then try using different sizes and prime numbers for them.


I'm working on replacing my rear wall Skyline with one that will use the prime number=2,381 with a least primitive root=3 and will be 68columns wide by 35 rows high. You may also wish to consider using the smallest dimensioned wooden pieces you can find as that impact the highest frequencies that it'll diffuse to. I could only find 1.5"*1.5" blocks of wood which will work up to 4.5kHz which is higher than the highest note on a piano. Depending on how close your seating distance is to the back wall, you should aim for diffusion down to about 300Hz which is the transition frequency of most domestic rooms. A good rule of thumb is to have your listening seat 3 wavelengths away from the lowest diffused frequency to allow ample space for the diffused sound to coallesce. So, if 300Hz is 45.2" long, then you should try and sit 135.6" from the back wall. If possible your deepest cell depths should be a large percentage of the 300Hz wavelength - 50% is really good to shoot for, which equates to your longest wooden pieces being 22.6" in length (50% * 45.2=22.6). Then consider filling in the spaces above, below, besides the skyline with bass traps that should work from 300Hz and deeper.


Massenburg's Studio C at Blackbird Studios may well use one extremely large prime number for the back wall, the same number for the side walls and also for the front wall and ceiling. As you're not far from the Studio, why don't you pay them a visit? I'd love to know how they're supporting their longest rods - they must have bored a hole and inserted a support pole through its backing or something . . .


If you care to see a pic of my skylines then PM me.


Kevin


----------



## kevinzoe




> Quote:
> Originally Posted by *pepar* /forum/post/18836936
> 
> 
> Does anybody know if there are any 3rd party comparisons of the various diffusors on the market? Prices are all over the place and I'm not 100% sure that the manufacturer-supplied data is apple-to-apples.
> 
> 
> And if somebody has some proprietary information, I'd consider _buying_ it if it's not too expensive. PM me on this, and I'd sign an NDA.
> 
> 
> Jeff




Hi Jeff,

I've found that most diffusion manufacturers exagerate their claims at least when using physics and common sense to evaluate low end diffusion capabilities, which is based on cell/well depth. So, self education rather than standard 3rd party testing seems like the only real viable solution today. Part of the problem is that there aren't the same diffusion and scattering coefficients as there are for absorption. I believe that RPG's President is trying to lobby to get some standard definitions and measurement practices in place which would theoretically allow easier inter-company product comparisons.


good luck,

kevin


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/0
> 
> 
> 
> ... self education rather than standard 3rd party testing seems like the only real viable solution today.
> 
> 
> good luck,
> 
> kevin



Thanks, with no simple DIY solution available as with absorbers and all of the vendors very "proud" of theirs, the cost really adds up quickly making an informed purchase even more important.


Jeff


----------



## johnbomb

Thanks, Kevin, for the info. I plan to use 2x4s and rip them to 1 in x 1 in rods with my bandsaw and planer. This will bring the diffusion effectiveness up to around 6800hz.


Also, I'm considering adding a twist: I may obtain some gravel (around 1 to 1.5 cm rocks) and dip each rod end in glue and then into the gravel before I mount them on the grid. The idea is to create additional surfaces to diffuse the higher frequencies. I'll then spray the whole thing black and again with a clearcoat- should look pretty unusual.


If I'm not mistaken, the absorption coefficients of pine are pretty low across the spectrum- in the 0.1 range or so, so pine 2x4s should be a reasonable choice for wood.


John


----------



## nathan_h

GIK has just introduced a diffuser based on some appropriate math that appears to be the cheapest in the marketplace. I don't know whether these are the best in all applications, nor more effective than the competition, and I neither work for GIK, nor have I purchased any of these from them. "7 root diffusor design that begins scattering at approx 350Hz and offers effective and even diffusion up through 3 kHz."


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Elill* /forum/post/18880166
> 
> 
> SMB - quick question, when you say "raw" does that mean you can just get the panel face and install that over "stuff" (insulation) you've sourced elsewhere? Or is it the complete panel, just uncovered/finished with fabric?
> 
> 
> 
> 
> I see RPG recommend you basically cover a room in this stuff, well hang panels covering quite a lot of area at any rate. They also seem to hang then in corners as bass traps?
> 
> 
> I suppose what I am getting at is can you over do it with this stuff? I assume you wouldn't want an entire room covered in it



Elill,


The perf-sorber raw and uncut comes in the assembled size (I think 4'x4' or 2'x4') and comes assembled. It does not ship "apart" with "some assembly required" stamped on the box. It means, you don't pay for custom cuts nor fabric assembly.


RPG's recommendation is not far off the mark in my opinion. You'll find, if the room is properly analyzed for a treatment strategy, that you can use quite a bit since it serves double duty (placement is key). You can buy the BAD panels either flat or with curved panels, but with a hard grate, it makes it a bit hard to customize yourself. The perf-sorbers are easier to manipulate in the field...hence the reason I like it better. You can always overdue things, especially in the pocketbook, which is the reason a proper acoustical analysis is a key element to any room. People always ask me "what do I get for an acoustical analysis package?" "Is it worth "x" amount of dollars?" I say, absolutely! Knowing where to place certain treatment methods and why you are doing it will *SAVE* money in the short term, not cost you more, so the analysis actually is worth the price of admission to many people...unless you weren't expecting to spend that amount in treatment anyway. The problem here is, it isn't a subwoofer, or a Blu-ray player, or an amplifier. It isn't tangible. People don't realize the worth until they hear it for the first time...THEN they proclaim money well spent. Just my 2 cents. Best wishes!


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/18884554
> 
> 
> Thanks, Kevin, for the info. I plan to use 2x4s and rip them to 1 in x 1 in rods with my bandsaw and planer. This will bring the diffusion effectiveness up to around 6800hz.
> 
> 
> Also, I'm considering adding a twist: I may obtain some gravel (around 1 to 1.5 cm rocks) and dip each rod end in glue and then into the gravel before I mount them on the grid. The idea is to create additional surfaces to diffuse the higher frequencies. I'll then spray the whole thing black and again with a clearcoat- should look pretty unusual.
> 
> 
> If I'm not mistaken, the absorption coefficients of pine are pretty low across the spectrum- in the 0.1 range or so, so pine 2x4s should be a reasonable choice for wood.
> 
> 
> John





Hi John,

Good for you on getting wood cut down to 1"*1" as it will indeed work up to about 6750-6800Hz. Incidentally, this is the same size wooden pieces that Massenberg used in his Studio C at Blackbird Studios. You're in good company!


Regarding the gravel idea: I like the creativity but allow me to play devil's advocate if for no other reason than to allow you to think through it more or to offer another "set of eyes" so to speak . . . Firstly, how long will the longest wooden pieces be in length because the gravel will add a lot of relative weight that glue may not be stong enough to support, especially since the weight is at the end of the rod where support is needed the greatest? Perhaps putting a long screw/bolt and washer through the back of the board and into the wooden piece will help.


Secondly, the depths of the wells are optimized using the prime number theory. By partially "plugging" the cell openings with gravel you're altering the effective cell depth which is likely to reduce the overall diffusion effectiveness, moreso for the lower notes than the higher I'd guess.


Thirdly, the diffused sound from gravel may "sound" different than wood - hard to say without really experimenting.


Fourthly, it is the partial pressure between the cells that determines the upper diffusion limit which is why 1"*1" cells will operate higher than larger dimensioned cells. So, I would expect that the gravel will cause the 1"*1" cell spacing to be reduced thereby extending your upper freq diffusion range even higher - a good thing.


Have you considered using your gravel on say a hemi-cylindrical (poly diffuser) diffuser instead of the Skyline type? Your milage with the gravel might go further on this type of diffuser rather than the Skyline . . .


Cheers,

kevin


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/18884944
> 
> 
> GIK has just introduced a diffuser based on some appropriate math that appears to be the cheapest in the marketplace. I don't know whether these are the best in all applications, nor more effective than the competition, and I neither work for GIK, nor have I purchased any of these from them. "7 root diffusor design that begins scattering at approx 350Hz and offers effective and even diffusion *up through 3 kHz*."



Hmmm, the D1 is said to have a "usable range of approximately 500Hz to over 10kHz" so wouldn't that seem to be a step or two down in performance?


Jeff


----------



## Elill




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/18885045
> 
> 
> People don't realize the worth until they hear it for the first time...THEN they proclaim money well spent. Just my 2 cents. Best wishes!



Hi SMB - thanks for the clarrifaction, no need to sell the value to me, I'm converted - I'll use our local guys though, which there is only two of.....complete joke this country when it coems to AT


----------



## ExToker

I could use some help here.

First off, I accidentally posted this on the audio theory thread so forgive me if you noticed I doubled up the question. I've requested a delete thread on that end from the mods.


Now then, let me try this again










I was the unfortunate recipient of a table I made for my wife a few years ago. She insists it stay where it is, as 'my room' has slowly fallen into the grasp of the WAF over the past 2 years.


Table size is 42" x 42" x 17" Room size is 13-6" x 20-6" x 7-3"


As you can see, it is an acoustical nightmare. However, all is not lost as I have the option to modify it ..... My thoughts


1. Replacing the 1/4" glass top with plywood, closing up the sides, and loading it with an absorbent.

2. 'Breathable' side panels, plywood top, absorbent

3. ?? suggestions??


Unfortunately whatever mods I make have to be reversible so a bass trap would be limited, since I wouldnt be able to glue and screw anything substantially.


It looks like there is a save here, I just cant see it clearly









Any Help out there ?


----------



## nathan_h

Sure, fill it with insulation, cover the sides with fabric. Only replace the glass on top with wood if you don't like the look of the insulation below the glass. It'll be like a bass trap in the middle of the room. Not ideal, and won't take care of reflections off the table top, but we work with what we have eh?


----------



## ExToker




> Quote:
> Originally Posted by *nathan_h* /forum/post/18892292
> 
> 
> Not ideal, and won't take care of reflections off the table top, but we work with what we have eh?



Yeah I'm not expecting to 'make a wrong a right', just as close to a neutral performance as I can if thats the best I can do.

The wood top switch is a certainty, and I can come up with enough crap to put on top to break up the reflection(s).


What to do with the cavity is the biggest question I have. I am no pro by any stretch of the imagination........should I have a remote concern of over-absorption given the close proximity to the LP.

I have some 2" OC703. Should I try attaching some to the bottom of the wood top to quiet the reflections in the cavity somewhat and skip the fluffy?

Or maybe wrap the perimeter in 703?


Aaannndd.....while I'm hammering you guys with questions, would you recommend rabbeting a piece of 3/4" plywood (vs. 1/4") to fit in the existing 1/4" glass slot to help with the resonance on the top?


Thanks


----------



## Kal Rubinson




> Quote:
> Originally Posted by *ExToker* /forum/post/18892265
> 
> 
> 1. Replacing the 1/4" glass top with plywood, closing up the sides, and loading it with an absorbent.
> 
> 2. 'Breathable' side panels, plywood top, absorbent
> 
> 3. ?? suggestions??



I would go with 2 and, in fact, I did. I took an similarly-sized ottoman and stuffed it with OC705. Of course, it had a pillow-top that is much less reflective than either glass or plywood and it had an open bottom so I added a mesh retainer. It turns out to be fairly effective.


----------



## ExToker

Thats very interesting Kal. I just had a flash when you mentioned the mesh. What I could get away with on top vs. plywood is a frame insert. Using a center support each way and 4 sections of semi open-weave cane webbing panels. That way the top would be able to breath (functional) and still be attractive to 'the boss'. And as it turns out I have an extra case of 703 (6 x 2").

This may not be all that bad after all. Thanks!


----------



## johnbomb




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18885702
> 
> 
> Hi John,
> 
> Good for you on getting wood cut down to 1"*1" as it will indeed work up to about 6750-6800Hz. Incidentally, this is the same size wooden pieces that Massenberg used in his Studio C at Blackbird Studios. You're in good company!
> 
> 
> Regarding the gravel idea: I like the creativity but allow me to play devil's advocate if for no other reason than to allow you to think through it more or to offer another "set of eyes" so to speak . . . Firstly, how long will the longest wooden pieces be in length because the gravel will add a lot of relative weight that glue may not be stong enough to support, especially since the weight is at the end of the rod where support is needed the greatest? Perhaps putting a long screw/bolt and washer through the back of the board and into the wooden piece will help.
> 
> 
> Secondly, the depths of the wells are optimized using the prime number theory. By partially "plugging" the cell openings with gravel you're altering the effective cell depth which is likely to reduce the overall diffusion effectiveness, moreso for the lower notes than the higher I'd guess.
> 
> 
> Thirdly, the diffused sound from gravel may "sound" different than wood - hard to say without really experimenting.
> 
> 
> Fourthly, it is the partial pressure between the cells that determines the upper diffusion limit which is why 1"*1" cells will operate higher than larger dimensioned cells. So, I would expect that the gravel will cause the 1"*1" cell spacing to be reduced thereby extending your upper freq diffusion range even higher - a good thing.
> 
> 
> Have you considered using your gravel on say a hemi-cylindrical (poly diffuser) diffuser instead of the Skyline type? Your milage with the gravel might go further on this type of diffuser rather than the Skyline . . .
> 
> 
> Cheers,
> 
> kevin



Good thoughts, there, Kevin- thanks. The gravel/poly idea is pretty interesting if for no other reason than it would look pretty cool! I think you're right about the gravel/rod idea, and I'm thinking that it's more trouble than it's worth anyway.


John


----------



## A9X-308




> Quote:
> Originally Posted by *Elill* /forum/post/18889905
> 
> 
> I'll use our local guys though, which there is only two of.....complete joke this country when it coems to AT



Don't complain, DIY and save lots of money. Absorbers are straightforward to design and build, and PRD/QRD diffusers nearly as. An Aussie (Collo) has written a neat little program to design the beasts based upon the Cox and D'Antonio book and there have been several builds so far. Lots more info on this at Gearslutz . Look at the specs of the commercial designs and work from there.


----------



## pepar




> Quote:
> Originally Posted by *A9X-308* /forum/post/18900234
> 
> 
> Absorbers are straightforward to design and build, and PRD/QRD diffusers nearly as. An Aussie (Collo) has written a neat little program to design the beasts based upon the Cox and D'Antonio book and there have been several builds so far. Lots more info on this at Gearslutz . Look at the specs of the commercial designs and work from there.



Thanks.


Jeff


----------



## A9X-308

Forgot to add in the links: QRD/PRD general stuff. 
QRDude software 
Bob Gold's Absorption Coefficients page


----------



## Elill




> Quote:
> Originally Posted by *A9X-308* /forum/post/18900234
> 
> 
> Don't complain, DIY and save lots of money. Absorbers are straightforward to design and build, and PRD/QRD diffusers nearly as. An Aussie (Collo) has written a neat little program to design the beasts based upon the Cox and D'Antonio book and there have been several builds so far. Lots more info on this at Gearslutz . Look at the specs of the commercial designs and work from there.



Thanks, but the treatment strategy I want to pursue goes beyond hanging "absorbers" around the place and building QRD's


I'm not of the opinion that just hanging up fluff is all that effective - I'd prefer a membrane solution or rather a diffusion grating like a BAD or perf-sorber


I do however like the flutter-free DIY solution, but figuring that out for the ceiling isn't an easy task in a small room without mugh height


And I'll stand by my comments that AT in Australia, as a profession is a cottage industry, with the exception of a handful of HAA people and a few others - different for commercial work, but in residential situations there just isn't much going. Not sure how many decent professionals there are per capita in the US, probably not many, I guess it just happens that 2-3 of them hang out at AVS which gives me the perceived notion that there are lots of them


Edit - and its not about the money, DIY or not, I want a solution I'm happy with - I wasn't having a go at DIY you outlined, I just think there are better/more effective options out there, particularly for such a small room


----------



## Drew_V

Can someone give me some advice on how big corner bass traps need to be?


My approach will be to cut OC703 panels into triangles and stuff them into the corners of the room. But I want to know how many triangles I can get out of one sheet. Depending on how I cut the sheet, I figure it could be anywhere from 4 to 16 (2 feet per side with 4 triangles or 1 foot per side at 16 triangles).


How many I can get out of each panel makes a huge difference in cost. So how big do they need to be?


----------



## pepar




> Quote:
> Originally Posted by *Drew_V* /forum/post/18909540
> 
> 
> Can someone give me some advice on how big corner bass traps need to be?
> 
> 
> My approach will be to cut OC703 panels into triangles and stuff them into the corners of the room. But I want to know how many triangles I can get out of one sheet. Depending on how I cut the sheet, I figure it could be anywhere from 4 to 16 (2 feet per side with 4 triangles or 1 foot per side at 16 triangles).
> 
> 
> How many I can get out of each panel makes a huge difference in cost. So how big do they need to be?



The bigger they are, the deeper they reach. Have you done any measuring to see what's happening in your room?


I would think that 8 triangles per 24" x 48" sheet would be the minimum size worth using. That's what I used - 24" faces, but if I had had the space, I would have made 4 per sheet and had 34" faces. Whether you spend x or 2x, the "x" is very small in relation to the benefit. There is some test data here .


I am not an acoustician, nor did I stay at a ...


----------



## ExToker

If possible, could someone please give me a simple definition (if one exists)

of 'critical frequency'?

Been reading a lot lately and I dont quite get it.


----------



## nathan_h

Context?


----------



## ExToker

I get it (finally). Owens Corning has a pretty good page here:
http://www.owenscorning.com/around/s...finitions.html


----------



## pepar




> Quote:
> Originally Posted by *ExToker* /forum/post/18911314
> 
> 
> If possible, could someone please give me a simple definition (if one exists)
> 
> of 'critical frequency'?
> 
> Been reading a lot lately and I dont quite get it.



For me it is the number of frozen margaritas I can make before exceeding the icemaker's throughput.


----------



## ExToker









I would have been disappointed if someone didnt step up to take advantage of that question.

I was actually waiting for a comment about how often one needs to be with their partner.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *ExToker* /forum/post/18911314
> 
> 
> If possible, could someone please give me a simple definition (if one exists)
> 
> of 'critical frequency'?
> 
> Been reading a lot lately and I dont quite get it.



From Linkwitz: "he frequency fs is also called the Schroeder frequency and denotes approximately the boundary between reverberant room behavior above and discrete room modes below."


----------



## Mark P

Any cool pics in this thread, I remember reading it front to back a couple years ago but............trying that again was headache inducing.


Simple home made, DIY, drag a mirror down the wall and ceiling and make some cool panel pictures?


----------



## ExToker




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/18916654
> 
> 
> From Linkwitz: "he frequency fs is also called the Schroeder frequency and denotes approximately the boundary between reverberant room behavior above and discrete room modes below."



Kal,


Your definitions better....OC's is simpler









"Critical Frequency*:* The frequency below which standing waves cause significant room modes."


The good news for me is I actually understood both!


Thanks


----------



## kevinzoe

Quote:

Originally Posted by *Mark P* 
Any cool pics in this thread, I remember reading it front to back a couple years ago but............trying that again was headache inducing.


Simple home made, DIY, drag a mirror down the wall and ceiling and make some cool panel pictures?
Mark,

Ok, I'll bite . . . allow my indulgence to show a little of my room's treatments.


Skylines are based on a prime number large enough to cover the intended wall area where the number of rows multiplied by the number of columns equals the prime number less 1. Max cell depth is 10" and block sizes are 1.5"*1.5". Blocks are polyurethaned to show the pine better.


Hemi-cylindrical diffusers double as bass traps as their concave interior is stuffed with OC 701 fiberglass while the outer side (facing into the room) is a red oak laminate hard enough so as not to absorb mid/high frequencies. Their humble beginings were from a 12 foot long, 48 inch diameter Sonotube. Five of them are in use and range from 160degree to 100degree arcs.


Cheers,

kevin

 

DIY Skyline Diffuser.pdf 172.0263671875k . file

 

Hemi-Cylindrical Difusser and Bass Trap.pdf 154.86328125k . file

 

Skyline difussion and bass traps.pdf 130.509765625k . file


----------



## Mark P




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18923892
> 
> 
> Mark,
> 
> Ok, I'll bite . . . allow my indulgence to show a little of my room's treatments.
> 
> 
> Skylines are based on a prime number large enough to cover the intended wall area where the number of rows multiplied by the number of columns equals the prime number less 1. Max cell depth is 10" and block sizes are 1.5"*1.5". Blocks are polyurethaned to show the pine better.
> 
> 
> Hemi-cylindrical diffusers double as bass traps as their concave interior is stuffed with OC 701 fiberglass while the outer side (facing into the room) is a red oak laminate hard enough so as not to absorb mid/high frequencies. Their humble beginings were from a 12 foot long, 48 inch diameter Sonotube. Five of them are in use and range from 160degree to 100degree arcs.
> 
> 
> Cheers,
> 
> kevin



Man thats alot of work you did there!


----------



## pepar

I was thinking the same thing. Vendors of commercial diffusors have nothing to worry about from some DIY diffusor craze sweeping the land.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Mark P* /forum/post/18917509
> 
> 
> Any cool pics in this thread, I remember reading it front to back a couple years ago but............trying that again was headache inducing.



I'm in the same boat, read the whole thread a couple years ago, but forgot much of it since then - I must be a sucker for punishment, as I'm back for a second helping (I'm on page 100 or so on my iPhone - but going through it little by little to help me fall asleep at night







). Hopefully this time through I apply what I learned before it slips from my porous brain again. Time to dig that Everest book out of storage again too.


Edit: Mark did you ever get around to posting the video of your theater construction? Awesome movie palace there, glad to see you're still evolving it.


----------



## A9X-308




> Quote:
> Originally Posted by *pepar* /forum/post/18925858
> 
> 
> I was thinking the same thing. Vendors of commercial diffusors have nothing to worry about from some DIY diffusor craze sweeping the land.



True but only in the sense that DIY audio anything is a small niche compared to commercial offerings.


Given Collo's excellent free software, I'd rather DIY a skyline than pay for someone else to build it. It's not difficult or even all that time consuming.


----------



## Weasel9992




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18923892
> 
> 
> Mark,
> 
> Ok, I'll bite . . . allow my indulgence to show a little of my room's treatments.
> 
> 
> Skylines are based on a prime number large enough to cover the intended wall area where the number of rows multiplied by the number of columns equals the prime number less 1. Max cell depth is 10" and block sizes are 1.5"*1.5". Blocks are polyurethaned to show the pine better.
> 
> 
> Hemi-cylindrical diffusers double as bass traps as their concave interior is stuffed with OC 701 fiberglass while the outer side (facing into the room) is a red oak laminate hard enough so as not to absorb mid/high frequencies. Their humble beginings were from a 12 foot long, 48 inch diameter Sonotube. Five of them are in use and range from 160degree to 100degree arcs.
> 
> 
> Cheers,
> 
> kevin



Dude, those diffusers are sweet.


Frank


----------



## Mark P




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/18927041
> 
> 
> I'm in the same boat, read the whole thread a couple years ago, but forgot much of it since then - I must be a sucker for punishment, as I'm back for a second helping (I'm on page 100 or so on my iPhone - but going through it little by little to help me fall asleep at night
> 
> 
> 
> 
> 
> 
> 
> ). Hopefully this time through I apply what I learned before it slips from my porous brain again. Time to dig that Everest book out of storage again too.
> 
> 
> Edit: Mark did you ever get around to posting the video of your theater construction? Awesome movie palace there, glad to see you're still evolving it.



Heh I actually built an "economy" theater in the guest house since then and use it instead........Im still sort of waiting for technology to get perfected in the automation and projector world.......nothing worse than having a 25k projector that gets blown away by a $1500 1080P Bestbuy junker










I couldnt wait for any pictures so I just whipped up some quicky treatments for the guesthouse theater yesterday


----------



## pepar




> Quote:
> Originally Posted by *A9X-308* /forum/post/18927799
> 
> 
> True but only in the sense that DIY audio anything is a small niche compared to commercial offerings.
> 
> 
> Given Collo's excellent free software, I'd rather DIY a skyline than pay for someone else to build it. It's not difficult or even all that time consuming.



I guess it's all what one is comfortable with. I look at absorbers and think "piece of cake" but I look at "cityscape" diffusors and I get a headache.


Jeff


----------



## kevinzoe




> Quote:
> Originally Posted by *Weasel9992* /forum/post/18927888
> 
> 
> Dude, those diffusers are sweet.
> 
> 
> Frank



Thanks Frank for the kind words. You/GIK may be pleasantly surprised to see that my back wall uses your products - lots of them! When looking at the back wall picture (third file listed in my earlier reply), the left corner uses 8 GIK Tri-Traps for a 24"wide * 24"deep * 7feet high rectangular shaped bass trap with 6" air space between it and the two walls. I've stood the Tri's on their ends and made a square shape, then added 4 more on top. That equals a 30" total depth which equates to one-quarter of a 113Hz wavelength for absorption purposes, and higher.


The right corner has 4 GIK Monsters in it - 2 stacked on top of 2 others. While the middle of the wall has 2 GIK Monsters + 4 242's pulled out from the wall about 25". Lots of $$ in bass traps for the back wall, that's why I decided to build my own for the other areas of the room; what started as a cost savings idea turned into a fun education session. Mid/high freqency diffusion and low bass trap in a single product makes for a great idea (which others have done long before I got around to trying it of course). . .


----------



## kevinzoe




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/18927041
> 
> 
> I'm in the same boat, read the whole thread a couple years ago, but forgot much of it since then - I must be a sucker for punishment, as I'm back for a second helping (I'm on page 100 or so on my iPhone - but going through it little by little to help me fall asleep at night
> 
> 
> 
> 
> 
> 
> 
> ). Hopefully this time through I apply what I learned before it slips from my porous brain again. Time to dig that Everest book out of storage again too.
> 
> 
> Edit: Mark did you ever get around to posting the video of your theater construction? Awesome movie palace there, glad to see you're still evolving it.



Brad,

Personally, I got more milage from Toole's latest book rather than from Everest's book. I recommend you pick up and read Dr Floyd Toole's book for a 'refresher.'


----------



## A9X-308

Quote:

Originally Posted by *pepar* 
I guess it's all what one is comfortable with. I look at absorbers and think "piece of cake" but I look at "cityscape" diffusors and I get a headache.


Jeff
Then I guess you really haven't looked at Collo's software.


Once you have decided on the parameters for the diffuser, input the data, and click the 2D button and you'll get a screen like this (without the explanation bubbles - I've pinched this from Collo's online manual).











Then click Export → Generate 2D Report and it generates a .txt with the length and placement of each block, the numbers of each length and the total length of timber required (user I think needs to account for differences due to cutting and sanding). For a 1000Hz, n=7, 50mm square block, you get the following (extract from full .txt attached):

*Block details

=============

Block width 50 mm


Number of empty wells 8

8 blocks of height 1 depth units, or 25 mm

8 blocks of height 2 depth units, or 49 mm

8 blocks of height 3 depth units, or 74 mm

8 blocks of height 4 depth units, or 99 mm

8 blocks of height 5 depth units, or 124 mm

1 blocks of height 6 depth units, or 148 mm

----------------------------------------

Total block length 3.11 metres*


If you can follow instructions, cut, sand and glue wood then you can build one of these. No harder than stacking Jenga sticks of different lengths together nor than an absorber build.

 

qrdude_2d.txt 3.912109375k . file


----------



## pepar




> Quote:
> Originally Posted by *A9X-308* /forum/post/18930834
> 
> 
> Then I guess you really haven't looked at Collo's software.
> 
> 
> If you can follow instructions, cut, sand and glue wood then you can build one of these.










It's not the software, it's the cutting, sanding and gluing all those blocks. But still, I might give it a try when I get to that point in my theater upgrade.


Thanks.


Jeff


----------



## nathan_h




> Quote:
> Originally Posted by *A9X-308* /forum/post/18930834
> 
> 
> Then I guess you really haven't looked at Collo's software.
> 
> 
> Once you have decided on the parameters for the diffuser, input the data, and click the 2D button and you'll get a screen like this (without the explanation bubbles - I've pinched this from Collo's online manual).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Then click Export → Generate 2D Report and it generates a .txt with the length and placement of each block, the numbers of each length and the total length of timber required (user I think needs to account for differences due to cutting and sanding). For a 1000Hz, n=7, 50mm square block, you get the following (extract from full .txt attached):
> 
> *Block details
> 
> =============
> 
> Block width 50 mm
> 
> 
> Number of empty wells 8
> 
> 8 blocks of height 1 depth units, or 25 mm
> 
> 8 blocks of height 2 depth units, or 49 mm
> 
> 8 blocks of height 3 depth units, or 74 mm
> 
> 8 blocks of height 4 depth units, or 99 mm
> 
> 8 blocks of height 5 depth units, or 124 mm
> 
> 1 blocks of height 6 depth units, or 148 mm
> 
> ----------------------------------------
> 
> Total block length 3.11 metres*
> 
> 
> If you can follow instructions, cut, sand and glue wood then you can build one of these. No harder than stacking Jenga sticks of different lengths together nor than an absorber build.



This is awesome. I didn't grok the full extent of what this app could do when it was first mentioned. Thanks for posting these details. I've now placed this near the top of my pile of projects for my theater!


----------



## pepar

Would a 2D QRD be appropriate to replace 2" OC703 absorbers on the rear wall (at the first reflection point)? The rear seats are approx 6' from the rear wall.


Thanks,

Jeff


----------



## johnbomb




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18923892
> 
> 
> Mark,
> 
> Ok, I'll bite . . . allow my indulgence to show a little of my room's treatments.
> 
> 
> Skylines are based on a prime number large enough to cover the intended wall area where the number of rows multiplied by the number of columns equals the prime number less 1. Max cell depth is 10" and block sizes are 1.5"*1.5". Blocks are polyurethaned to show the pine better.
> 
> 
> Hemi-cylindrical diffusers double as bass traps as their concave interior is stuffed with OC 701 fiberglass while the outer side (facing into the room) is a red oak laminate hard enough so as not to absorb mid/high frequencies. Their humble beginings were from a 12 foot long, 48 inch diameter Sonotube. Five of them are in use and range from 160degree to 100degree arcs.
> 
> 
> Cheers,
> 
> kevin



Nice work, Kevin- I like the "picture frame" around the rods. How long did it take you to build those skylines?


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/18933164
> 
> 
> Nice work, Kevin- I like the "picture frame" around the rods. How long did it take you to build those skylines?



Hi John,

Thanks for the compliment. The "picture frame" was designed to hide the 3.5" decking screws that secure the very heavy Skyline to the wooden 2"*4"s behind the drywall. I used velcro to stick the frame to the plywood backing that extends 3" around the perimeter from the Skyline blocks to allow enough room to put the required deck screws in.


The back wall with +1,500 wooden blocks took about 2-3 months working part time on it and working through a learning curve. The smaller one on the side wall near the back took but 2-3 weeks as a result of being smaller (less wood to cut) and improved learnings for better efficiency.


Although you didn't ask, the hemi-cylindrical diffusers were even less time. It involved cutting the right shape/size, sanding the exterior to remove the wax and glueing wood laminate to it and building a wooden frame on the back, stuffing it with OC 701 and wrapping it in plastic to prevent air borne fibreglass particles. Then polyurethaning it. One hemi took about 1 week of part time work in the evenings.


----------



## johnbomb




> Quote:
> Originally Posted by *kevinzoe* /forum/post/18933264
> 
> 
> The back wall with +1,500 wooden blocks took about 2-3 months working part time on it and working through a learning curve. The smaller one on the side wall near the back took but 2-3 weeks as a result of being smaller (less wood to cut) and improved learnings for better efficiency.



What kind of learning curve did you experience? As I'm probably going to build several of these things, any tips/tricks are appreciated.


Thanks,

John


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/18933357
> 
> 
> What kind of learning curve did you experience? As I'm probably going to build several of these things, any tips/tricks are appreciated.
> 
> 
> Thanks,
> 
> John



John - I've put together some thoughts on building a Skyline based on an existing patent and using the best online calculator I could find.


By the way, the 2D Skyline looks similar to an earlier post of a 2D QRD but I believe they are different beasts. The Skyline never has the same number of rows as columns, and vice-versa, whereas the 2D QRD has the same number of columns as rows due to the repeating pattern both vertically and horizontally. Skylines have no repeating pattern and appear more 'random' in their appearance to max diffusion effectiveness. I think the 2D QRD is meant to have the varying cavity depths point into the room while its Skyline-lookalike backing faces the wall. This would make sense and appears similar to RPG's Hemiffusor ( http://www.rpginc.com/products/hemiffusor/index.htm ).


On to building a Skyline . . .

**********

Creating a DIY Skyline Diffuser

*Background*: I wanted to add diffusion to my dedicated 2-channel stereo room rather than mid and high frequency (MF/HF) absorption to prevent over damping the room. This document walks the reader through how to build them and what's involved.

*Why Use Skylines?* A skyline diffuser is a two-dimensional tool - meaning it scatters sound waves vertically and horizontally - and is used primarily to add listener envelopment and to remove flutter echo. Diffusion and/or MF/HF absorption can also be used to improve timbre and localization of instruments in space by affecting 1st angle reflection points. The Skyline can work within smallish rooms due to the scattering abilities within the two dimensions allowing listeners to sit closer to them than a 1-dimension diffuser which requires positioning further away for the diffused sound to coalesce by the time it gets to the listener. I also was concerned about not creating a dead sounding' room as much of the MF/HF were already being absorbed by a low pile wall-to-wall carpet with underpad and a large number of resistive-type bass traps (i.e. fiberglass filled) that continue to absorb up into the mid-frequencies which is cumulative with the more bass traps you have.

*Where to Locate Skylines?* Current wisdom is to cover the back wall and rear parts of the side wall behind and up to the listening position. These locations help envelop the listener with a reverberant sound field that when mixed with the direct sound field from the speakers creates a balanced mix of both at the listening position. Ceiling first reflection points are another natural spot for them as the Skylines act as if they are raising the ceiling.

*What Tools Are Needed?*

 Measuring tape

 Mieter saw (sometimes called a Chop saw)

 Belt/Disc Sander

 Ear and eye protection

 Carpenter's Level and Square

 Stud finder

 Paint or wood stain (e.g. polyurethane)



*What Materials Are Needed?*

 ½ or thicker plywood for the backing - be sure to get the type with one side finished as you'll see the backing in the empty cells

 Lots of 2 * 2 wooden studs which are really 1.5 * 1.5. The least expensive is the construction grade with various pieces of wood finger jointed together - this is low grade/quality wood and you may prefer to paint it afterwards to hide blemishes etc. For my first project I used Pine and cut out the knots and painted it afterwards. It didn't look as good as my second project which used finished knotty Pine with a polyurethane finish. Any kind of wood should do.

 Some pieces of 1 * 4 boards that will form a picture frame-like trim - optional but I thought it finished the look.

 3.5 decking screws to secure the plywood backing to the studs behind your drywall as the Skyline will be HEAVY!

 Construction strength adhesive glue (e.g. Lepages PL Premium adhesive)

 Industrial strength Velcro to secure the picture frame-like trim to the plywood backing

*What Steps Are Involved?*

(A) Choosing a prime number & associated number of columns & rows for the chosen diffuser size you intend to build

(B) Cutting the wooden blocks

(C) Sanding the wooden blocks

(D) Painting or Staining the wooden blocks and empty cells

(E) Gluing the wooden blocks to the board

(F) Hanging the finished diffuser


*(A) Choosing a prime number & associated number of columns & rows*


For the definitive reference on the math formulas involved in this design, check out the US Patent office where RPG has filed their Skyline patent #5401921. You should be able to find it online by Googling it.


A general principle applicable to diffusers is that the less periodicity of the pattern, the more diffuse the scattering, which is a good thing. What this means is that you will need to find a large enough Prime number with corresponding column and row counts to fit within the size of the wall area you wish to cover with the diffuser, rather than several smaller diffusers put together. The less a pattern is repeated the better, hence try to find one prime number with enough columns and rows to cover your intended area.


See Appendix I for a partial list of prime numbers and dimensions (in inches).


I used the website * www.oliverprime.com/prd.php * to plan the diffuser.

_Step #1_: Click on Examples link to find a two column table. The left column titled P' represents sample prime numbers while the right column titled Grid' lists the corresponding column and row counts. The grid numbers are the number of cells, not the height or width in inches or centimeters. NOTE: the two grid numbers multiplied together should equal the Prime number minus 1. The grid numbers can be either columns * rows or vice versa, it doesn't matter.

_Step #2_: Determine the approximate area you want the diffuser to cover on your wall. Now take either the height or the width of your desired area and divide it by the dimension of the studs to calculate the number of cells you'll need. For example, let's say I want to cover a wall section roughly 48 high by 48 wide. If I divide 48 by 1.5 which is the size of my 1.5*1.5 blocks, then it equals 32 cells. So, ideally I would like to find a Prime number that is 32 cells high by 32 cells wide. However, looking at the list of Grid examples the only things that come closest are 30*19 or 33*20 or 36*31. I would elect to choose the last one (which corresponds to a Prime number of 1117 which is 1 cell (1.5) less than the desired height (or width) and 4 cells (6) greater than the desired width (or height). This is likely the best fit, providing you have the extra 6 otherwise you'll have to try different prime numbers until you settle on one that fits best.

_Step #3_: With the Prime number and corresponding grid size determined now click on the Links link and then click on the first hyperlink to calculate least primitive roots. This will open a window where you'll enter your Prime number and it will return a number that you'll use in Step #4. For my example, the prime number of 1117 has a least primitive root of 2.

_Step #4_: Now click on the Calculator link to play some what-if scenarios. Here is where you will enter various numbers that will all be considered to produce an output that tells you exactly what length stud to put where on your plywood.

Speed of Sound - leave this alone at 343 meters/second.

Lowest Frequency - put in how low you'd like your diffuser to work. Dr. Floyd Toole suggests in his latest book that the diffuser should work down to 300Hz and be a minimum of 8-12 inches deep. A 300Hz wavelength is 45.2 long and Toole suggests that the diffuser depth be a significant percentage of the wavelength. So at 50% of the 300Hz wavelength, you'd need a maximum cell depth of 22.6 which may be too long for typical residential rooms so 40% (18.1) or 30% (13.6) may be more appropriate lengths and still be good enough.



Be careful to plan by how much narrower or shorter your width and length of the room will become once the diffuser's long studs are on the wall. Keep in mind too that you should try and keep a minimum of 4feet between your listening position and the diffuser - the more distance the better. Finally, be sure that there are enough studs behind the drywall spaced across the diffuser's width to support its heavy weight.

Highest Frequency - put in 4,500Hz if you're using 1.5*1.5 blocks. While the longest length of the blocks determines the lowest frequency that the diffuser will work to, it is the block's dimension that determines the highest frequency. 4,500Hz is higher than the top note on a piano. If you can find a lumber mill to cut you 1*1 blocks then you can enter 6,750Hz. I wouldn't suggest anything smaller than 1*1 blocks.

Prime Number P - use the Prime number from Step #2

Primitive Root of P - use the least primitive root from Step #3

# of columns - use from Step #2

# of rows - use from Step #2

Quantize well heights within - this is where you indicate the incremental length that will be used for the studs. For example, 1.5 means that my stud lengths would be 0, 1.5, 3, 4.5, 6 etc. Note that the calculations are in centimeters so use 1=2.54 centimeters as your conversion factor. So stud length increasing by 1.5 corresponds to 3.81 centimeters.


What is outputted is a table of numbers corresponding to block length and their location based on the chosen Prime number.


For what it's worth, the George Massenberg designed Studio C at the Blackbird studios uses 1*1 dimensions and block lengths ranging from 1/10 to 30.



*Border*

For aesthetic reasons, I decided upon a picture frame-like border around the outer edges of the plywood. Of course a border can be any width you wish, but a 3 border width allowed the 1.5 cells to divide evenly into the remaining space of the plywood backing. Also, I can buy 1*4 lumber for the border which is really 1 by about 3.125 so I will have the border overhang the plywood just a tad. So, take your square and long straight edge which I used my Level for, to draw where the 3 borders will be and then all the cells inside the borders at 1.5 intervals. This takes a bit of time but will be helpful later on when it comes time to glue the right length stud to each cell. Finally, using the output from the website above, write the stud length in each cell. Be sure NOT to write a zero (0) in the empty cell because you'll see this empty cell.

*(B) Cutting the wooden studs*


Before getting ready to cut for a few hours, be sure to have a number of boxes, or bins, or buckets on hand in which to place the various length pieces of blocks being cut. I found several boxes and labeled them with a block length in order to find them easily when it came time for gluing. You might also consider a brand new saw blade given the hundreds of cuts about to be made.


Remember to think safety and wear ear and eye protection.


*(C) Sanding the wooden blocks*


If you can afford to purchase wood that is already dressed then you won't need to do the work in the following paragraph other than to sand one of the block's ends after cutting.


This is by far the most time consuming step depending on the quality level you want for the finished product. I had hoped to only have to sand the one end of the blocks that would be facing into the room but found that the four sides could also stand a sanding to smooth them out and remove minor blemishes. While many blocks will be pressed up against one another, you don't know how much of the sides will be visible so it's better safe than sorry and just do a quick sanding on 5 of the 6 sides. Furthermore, you may wish to get somewhat fancy and put a bevel on the end facing into the room by tilting the end of the block lightly on the sander to smooth the edge. Again be sure to wear ear and eye protection and also a mask to avoid inhaling saw dust.


It's a good idea to have a second/spare belt so as to minimize project delays. I used a 80 grit sandpaper and then a 200 grit to finish it off before staining them with polyurethane.


*(D) Painting/Staining the wooden blocks*


I thought a paint sprayer would be the fastest way to cover the wooden blocks in either a paint or stain. I'll admit I'm a novice to spray painting having thought how hard could it be . . . In actuality, too much paint came out and there are so many nooks and crannies to fill that I found myself quickly grabbing a paint brush to wipe the excess paint away and apply it to an unpainted area. I ended up painting each and every cell by hand with a long handled brush a little less than1 wide to allow it to fit into the deepest cells. Paint will hide the wood grain etc and for my first attempt at a Skyline helps hide my mistakes or shortcuts. For my next Skyline I opted to use Polyurethane to preserve the warmth and beauty of the wood grain. I simply dunked each piece of wood into the gallon can and set it aside to dry and then repeated the process a second time before glueing them onto the ½ plywood back board.

*(E) Affixing the wooden studs to the board*


I used Lepages PL Premium construction adhesive found at Home Depot. Gluing is easy but tedious work. Having marked the length for each cell on the plywood ahead of time it was easy to know what length goes where. I'd pull all the required pieces for a single row and put them in their cell locations and then start gluing. This allowed the glue that came out to be quickly applied to the next block with minimal glue waste. Repeat the process for the next row etc. When gluing focus on the end of the block facing into the room to be sure it's square with the blocks around it. Sometimes a block will be warped and when the bottom is properly fit within its cell you'll notice that the other end which faces into the room isn't square with the blocks around it so use the end facing into the room as your guide for gluing and positioning the blocks.


.
*(F) Hanging the finished product*


Typically, a diffuser of 4 foot height will be hung two feet above the floor. Due to its weight, you will need to screw the diffuser into 2*4 studs behind the (dry)wall which are usually 16 apart from one another. Use a stud finder to locate the wooden studs. Then use your tape measure, a straight edge, and pencil to find and mark the top and bottom and sides of where the diffuser will go. You will need some strong friends to hold the diffuser in place while you put screws in the top border. Alternatively, you can use the scrap pieces of your blocks to build a temporary shelf at the 2 foot mark above the floor to rest the diffuser on while you screw in the top and bottom border of the diffuser. You can further secure the diffuser by putting a screw in an empty cell if it aligns with a stud, although I didn't need to. Then remove the temporary shelf and patch and paint the screw holes.


Next, cut the 1 * 4 wooden planks to become the picture frame-like trim. You'll need to set your chop saw to 45 degrees to get the correct angle, as one example of fitting the border trim pieces together.


With the diffuser securely fastened to the wall, place the industrial strength Velcro around the plywood's borders and also on the underside of the wooden 1*4 border trim planks. Place the border trim planks onto the plywood ensuring each corner lines up. This will now hide the deck screws from view yet gives you the flexibility of removing the trim to access the screws if/when you want to move the diffuser to another wall, room, or house.


*Appendix I*


Partial List of Prime Numbers and Dimensions (in inches)


Prime # X Y Least Primitive Root X (") Y (")

157 12 13 5 18 19.5

163 54 3 2 81 4.5

167 83 2 5 124.5 3

173 43 4 2 64.5 6

179 89 2 2 133.5 3

181 20 9 2 30 13.5

191 19 10 19 28.5 15

193 64 3 5 96 4.5

197 28 7 2 42 10.5

199 18 11 3 27 16.5

211 15 14 2 22.5 21

223 37 6 3 55.5 9

227 113 2 2 169.5 3

229 19 12 6 28.5 18

233 29 8 3 43.5 12

239 17 14 7 25.5 21

241 16 15 7 24 22.5

251 25 10 6 37.5 15

257 128 2 3 192 3

263 131 2 5 196.5 3

269 67 4 2 100.5 6

271 18 15 6 27 22.5

277 23 12 5 34.5 18

281 20 14 3 30 21

283 47 6 3 70.5 9

293 73 4 2 109.5 6

307 18 17 5 27 25.5

311 31 10 17 46.5 15

313 24 13 10 36 19.5

317 79 4 2 118.5 6

331 22 15 3 33 22.5

337 21 16 10 31.5 24

347 173 2 2 259.5 3

349 29 12 2 43.5 18

353 22 16 3 33 24

359 179 2 7 268.5 3

367 61 6 6 91.5 9

373 31 12 2 46.5 18

379 21 18 2 31.5 27

383 191 2 5 286.5 3

389 97 4 2 145.5 6

397 22 18 5 33 27

401 25 16 3 37.5 24

409 24 17 21 36 25.5

419 22 19 2 33 28.5

421 21 20 2 31.5 30

431 43 10 7 64.5 15

433 27 16 5 40.5 24

439 73 6 15 109.5 9

443 26 17 2 39 25.5

449 28 16 3 42 24

457 24 19 13 36 28.5

461 23 20 2 34.5 30

463 22 21 3 33 31.5

467 233 2 2 349.5 3

479 239 2 13 358.5 3

487 54 8 3 81 12

491 35 14 2 52.5 21

499 83 6 7 124.5 9

503 251 2 5 376.5 3

509 127 4 2 190.5 6

521 26 20 3 39 30

523 29 18 2 43.5 27

541 27 20 2 40.5 30

547 26 21 2 39 31.5

557 139 4 2 208.5 6

563 281 2 2 421.5 3

569 71 8 3 106.5 12

571 30 19 3 45 28.5

577 64 9 5 96 13.5

587 293 2 2 439.5 3

593 37 16 3 55.5 24

599 26 23 7 39 34.5

601 25 24 7 37.5 36

607 101 6 3 151.5 9

613 36 17 2 54 25.5

617 28 22 3 42 33

619 103 6 2 154.5 9

631 30 21 3 45 31.5

641 32 20 3 48 30

643 107 6 11 160.5 9

647 34 19 5 51 28.5

653 163 4 2 244.5 6

659 47 14 2 70.5 21

661 30 22 2 45 33

673 32 21 5 48 31.5

677 52 13 2 78 19.5

683 31 22 5 46.5 33

691 30 23 3 45 34.5

701 28 25 2 42 37.5

709 236 3 2 354 4.5

719 359 2 11 538.5 3

727 33 22 5 49.5 33

733 61 12 6 91.5 18

739 41 18 3 61.5 27

743 53 14 5 79.5 21

751 375 2 3 562.5 3

757 28 27 2 42 40.5

761 38 20 6 57 30

769 32 24 11 48 36

773 193 4 2 289.5 6

787 131 6 2 196.5 9

797 199 4 2 298.5 6

809 101 8 3 151.5 12

811 162 5 3 243 7.5

821 41 20 2 61.5 30

823 137 6 3 205.5 9

827 118 7 2 177 10.5

829 36 23 2 54 34.5

839 419 2 11 628.5 3

853 71 12 2 106.5 18

857 107 8 3 160.5 12

859 33 26 2 49.5 39

863 431 2 5 646.5 3

877 73 12 2 109.5 18

881 40 22 3 60 33

883 42 21 2 63 31.5

887 443 2 5 664.5 3

907 302 3 2 453 4.5

911 35 26 17 52.5 39

919 34 27 7 51 40.5

929 32 29 3 48 43.5

937 72 13 5 108 19.5

941 47 20 2 70.5 30

947 43 22 2 64.5 33

953 56 17 3 84 25.5

967 42 23 5 63 34.5

971 97 10 6 145.5 15

977 61 16 3 91.5 24

983 491 2 5 736.5 3

991 45 22 6 67.5 33

997 83 12 7 124.5 18

1009 63 16 11 94.5 24

1013 44 23 3 66 34.5

1019 509 2 2 763.5 3

1021 60 17 10 90 25.5

1031 103 10 14 154.5 15

1033 43 24 5 64.5 36

1039 173 6 3 259.5 9

1049 131 8 3 196.5 12

1051 42 25 7 63 37.5

1061 53 20 2 79.5 30

1063 59 18 3 88.5 27

1069 89 12 6 133.5 18

1087 181 6 3 271.5 9

1091 109 10 2 163.5 15

1093 39 28 5 58.5 42

1097 137 8 3 205.5 12

1103 38 29 5 57 43.5

1109 277 4 2 415.5 6

1117 36 31 2 54 46.5

1123 34 33 2 51 49.5

1129 47 24 11 70.5 36

1151 46 25 17 69 37.5

1153 36 32 5 54 48

1163 83 14 5 124.5 21

1171 39 30 2 58.5 45

1181 59 20 7 88.5 30

1187 593 2 2 889.5 3

1193 149 8 3 223.5 12

1201 40 30 11 60 45

1213 101 12 2 151.5 18

1217 38 32 3 57 48

1223 47 26 5 70.5 39

1229 307 4 2 460.5 6

1231 41 30 3 61.5 45

1237 103 12 2 154.5 18

1249 39 32 7 58.5 48

1259 37 34 2 55.5 51

1277 44 29 2 66 43.5

1279 71 18 3 106.5 27

1283 641 2 2 961.5 3

1289 46 28 6 69 42

1291 43 30 2 64.5 45

1297 48 27 10 72 40.5

1301 50 26 2 75 39

1303 42 31 6 63 46.5

1307 653 2 2 979.5 3

1319 659 2 13 988.5 3

1321 40 33 13 60 49.5

1327 39 34 3 58.5 51

1361 40 34 3 60 51

1367 683 2 5 1024.5 3

1373 49 28 2 73.5 42

1381 46 30 2 69 45

1399 233 6 13 349.5 9

1409 44 32 3 66 48

1423 79 18 3 118.5 27

1427 46 31 2 69 46.5

1429 42 34 6 63 51

1433 179 8 3 268.5 12

1439 719 2 7 1078.5 3

1447 241 6 3 361.5 9

1451 50 29 2 75 43.5

1453 44 33 2 66 49.5

1459 54 27 3 81 40.5

1471 42 35 6 63 52.5

1481 40 37 3 60 55.5

1483 39 38 2 58.5 57

1487 743 2 5 1114.5 3

1489 48 31 14 72 46.5

1493 373 4 2 559.5 6

1499 107 14 2 160.5 21

1511 151 10 11 226.5 15

1523 761 2 2 1141.5 3

1531 45 34 2 67.5 51

1543 257 6 5 385.5 9

1549 43 36 2 64.5 54

1553 97 16 3 145.5 24

1559 41 38 19 61.5 57

1567 54 29 3 81 43.5

1571 157 10 2 235.5 15

1579 263 6 3 394.5 9

1583 113 14 5 169.5 21

1597 42 38 11 63 57

1601 50 32 3 75 48

1607 73 22 5 109.5 33

1609 67 24 7 100.5 36

1613 52 31 3 78 46.5

1619 809 2 2 1213.5 3

1621 45 30 2 67.5 45

1627 271 6 3 406.5 9

1637 409 4 2 613.5 6

1657 46 36 11 69 54

1663 277 6 3 415.5 9

1667 49 34 2 73.5 51

1669 139 12 2 208.5 18

1693 47 36 2 70.5 54

1697 53 32 3 79.5 48

1699 283 6 3 424.5 9

1709 61 28 3 91.5 42

1721 43 40 3 64.5 60

1723 42 41 3 63 61.5

1733 433 4 2 649.5 6

1741 58 30 2 87 45

1747 97 18 2 145.5 27

1753 73 24 7 109.5 36

1759 293 6 6 439.5 9

1777 48 37 5 72 55.5

1783 54 33 10 81 49.5

1787 47 38 2 70.5 57

1789 149 12 6 223.5 18

1801 45 40 11 67.5 60

1811 181 10 6 271.5 15

1823 911 2 5 1366.5 3

1831 61 30 3 91.5 45

1847 71 26 5 106.5 39

1861 60 31 2 90 46.5

1867 311 6 2 466.5 9

1871 55 34 14 82.5 51

1873 52 36 10 78 54

1877 67 28 2 100.5 42

1879 313 6 6 469.5 9

1889 59 32 3 88.5 48

1901 50 38 2 75 57

1907 953 2 2 1429.5 3

1913 239 8 3 358.5 12

1931 193 10 2 289.5 15

1933 46 42 5 69 63

1949 487 4 2 730.5 6

1951 50 39 3 75 58.5

1973 58 34 2 87 51

1979 46 43 2 69 64.5

1987 331 6 2 496.5 9

1993 83 24 5 124.5 36

1997 499 4 2 748.5 6

1999 54 37 3 81 55.5

2221 60 37 2 90 55.5

2243 59 38 2 88.5 57


**********


----------



## Elill

Skylines and flutter free seems somewhat straightforward to DIY - anyone done a DIY BAD? any tips on how to do it (other than learning CAD and getting a laser cutter/cnc to do it?). Dont suppose anyone has a CAD file for the grating?










I had thought about getting pegboard and using that as a guide i.e. use the existing holes as pilot holes and drill (or route) through multiple sheets at a time, just a concept, need to look at pegboard hole spacing


----------



## kevinzoe




> Quote:
> Originally Posted by *Elill* /forum/post/18934510
> 
> 
> Skylines and flutter free seems somewhat straightforward to DIY - anyone done a DIY BAD? any tips on how to do it (other than learning CAD and getting a laser cutter/cnc to do it?). Dont suppose anyone has a CAD file for the grating?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I had thought about getting pegboard and using that as a guide i.e. use the existing holes as pilot holes and drill (or route) through multiple sheets at a time, just a concept, need to look at pegboard hole spacing



Hi Elill,


Personal preferences aside, what do you see as special or attractive about Binary Amplitude diffusers?


While the peg board would appear as a good starting 'template' it's holes are likely not the right size and are spaced too regularily and not near random enough in their appearance for proper diffusion. Sorry, haven't BAD experience to pass along . . .


----------



## Elill

Hi Kevin, they cater for my needs to diffuse and absorb at certain frequencies in a small room.


Let me clarrify the point around the pegboard - its got a linear patten of holes, now I bet they're not centered in the same spacing as a BAD, but say if it was, buy some chance, I'd draw the BAD pattern on the pegboard sit that over something (thin ply) and drill through 1/2" holes.


Alternatively I could draw a grid and then drill, but that wont be as accurate in terms of getting the hole centers in the right spot (one thing I suck with is drilling accurately like that)


I am however thinking about the DIY skylines, I dont think it'd take me that long really, once you get into the swing of it. Depends on type and quality of finish. It is was paint thats easy, if I go for a timber, that'd be a little longer, but still quick if you set it up right. I'd-


- pre-sand and finish the 50x50 lengths

- cut a lot of the 6 different sizes

- stand them together and sand ends and finish

- glue to a backing board using construction adhesive

- let dry, screw through from the rear

- hang


The other thing I thought of was buying a bit of flutter-free, using that as a template for router bits and height and then spending a day running timber over a router table


----------



## johnbomb

Wow, Kevin, thanks!


John


----------



## kevinzoe




> Quote:
> Originally Posted by *johnbomb* /forum/post/18937431
> 
> 
> Wow, Kevin, thanks!
> 
> 
> John



You're welcome. I trust the info was/will be helpful.


Be sure to post pictures of your finished Skyline product(s) for all the world to see . . .


----------



## Dennis Erskine

Pegboard will behave more as a low pass filter rather than a diffuser.


----------



## Weasel9992

Wow Kevin. You are a wealth of information. Very, very cool.


Frank


----------



## Elill




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/18939445
> 
> 
> Pegboard will behave more as a low pass filter rather than a diffuser.



Hi Dennis, understood, I was going to use the pegboard as a hole centre guide for making a diffuser i.e. it would ensure manually drilled or routed holes were centered....can i be bothered? probably not.


General question though - how does one determine what frequency a perforated board will absorb? or rather how do I determine what hole depth and size will absorb certain frequencies? if someone can point me to a book/reference that'd be appreciated.


I like the perforated veneer look, but you can get it in all manner of shapes, sizes, designs


I have found this?


Freq = 200 x square root of (P/(D x T))


where:

P = perforation percentage (eg, 5%)

D = depth of air space (in inches)

T = PT + 0.8 x HD

where:

PT = panel thickness (in inches)

HD = hole diameter (in inches)


for absorbers with slats:


Freq = 216 x square root of (P/(D x PT))


where:

P = perforation percentage (eg, 5%)

D = depth of air space (in inches)

PT = panel thickness (in inches)


----------



## SierraMikeBravo

Hi Eill,


Keep in mind, there is more going on as well. The diffusive element requires a certain backing behind the material and the the "holes" act to DIFFUSE not absorb by their pattern, depth and size. Trevor Cox and Dr. D'Antonio wrote a textbook called *Active Absorption and Diffusion*. But be forewarned, this is essentially a Masters level text and a STRONG fundamental background in mathematics (i.e. ODE's) plus it is expensive. As with any math based text, it isn't all spelled out for you. It wasn't meant to be a DIY book. Many "fill in the blank calculations" i.e. what looks like a simple equation explodes into a 14 page derivative when you start working the equation. No "a" times "b" in that book. The only way to ensure you got it right is to measure it...with very expensive equipment and in an acoustic chamber. Testing new concepts is expensive which is why some of these types of panels cost so much...not to mention the assembly required and the R&D. All costs money, but you know it's right. Not everything is best done DIY unless you like to waste money and lots of time. If that is your cup of tea...go for it!







Perfsorber is also a lot cheaper than a BAD panel and you can do a lot more "things" with it. FYI, RPG is geared more towards commercial, not residential treatment. Just my 2 cents. Best wishes!


----------



## Elill

Hmm, ok thanks SMB (for the record one of my majors was in physical chem (read quantum mechanics).....could I still apply the math.....probably not










You and Dennis sure do a good job of scaring the ________ out of me!


Nothing is cheap in this country, well when it comes to this stuff (what does a perf-sorber panel cost in the US?) - The wife has read me the riot act again re the ever expanding "budget" so I'm leaning back to DIY territory


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Elill* /forum/post/18940477
> 
> 
> Hmm, ok thanks SMB (for the record one of my majors was in physical chem (read quantum mechanics).....could I still apply the math.....probably not
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You and Dennis sure do a good job of scaring the ________ out of me!
> 
> 
> Nothing is cheap in this country, well when it comes to this stuff (what does a perf-sorber panel cost in the US?) - The wife has read me the riot act again re the ever expanding "budget" so I'm leaning back to DIY territory



Then you should be ok regarding the math. It takes quite a bit of reviewing the 'ole texts, but it often comes back. I started with my 1st grade math book as a review and worked my way back up from there.







If DIY is on the budget, what I would do is consider buying the perfsorber or BAD panels outright, then DIY the rest. Saves lots of headaches and time etc. Cost is roughly 2/3 of what a BAD panel costs. When it comes to planning a budget, I guess it is best to know what things really are worth the money and what things aren't. I would put these (perfs), a proper design and good equalizers as my top three. The other things can always be upgraded and replaced at a later date. Again, just my 2 cents. I think the reason Dennis and I scare you with equal propensity is that we are on the same wavelength (i'll wait for the proper banter from Mr. Erskine...although he complains that he can't leave me alone for 5 minutes)







. Best wishes!


----------



## johnbomb

I would greatly appreciate some help with this one. I'm currently trying to figure out how to build an air return for my theater. I have a soffit running along the upper left wall/ceiling line, and I'm building a mirror image of it in the upper right wall/ceiling line.


I want to put a 12 inch duct in the mirror soffit, and leave both ends open: the end inside the theater will be "capped" with a perforated or cloth covered end piece to allow air to pass into the duct. The other end of the duct will pass through the rear theater wall and allow air to pass from the theater into the adjacent room (where a real return that feeds the HVAC lives).


This duct will be about 16 feet long.


I'm concerned that my theater will act as a giant speaker box, and the the duct will act as a "port" for this box. I ran a calculation on WinSD, and the predicted resonance for a port this long is around 30 hz or so. I have a double bass array as my subwoofer solution.


Will this be a problem? If so, do you have any suggestions as to how to avoid it. To put another way: what is the best way to return air from a theater?


Thanks,

John


----------



## Mark P

We used alot of this for supply and returns

http://www.specjm.com/products/ductboard/enviroaire.asp 

http://www.owenscorning.com/quietzon..._DataSheet.pdf 


Super easy to install and you can do it yourself, not sure about having them turn into giant ports, if anything they would add to the volume of the room and making them out of Duct board would give you huge bass traps?


----------



## Dennis Erskine

BAD panels (unlike PerfSorber) are better in larger rooms. Much like the Skylines, you have to be far enough way from them to acquire a fully randomized, homogenous sound field. In other words, sitting too close and (a) you can hear the panels; and, (b) at close distances they are doing more damage than good. Far enough away...they are great.


----------



## nathan_h

So my 13 x 17 x 7.5 foot room is probably not big enough for diffusion no matter where I am sitting, eh?


----------



## Dennis Erskine

No. You just need to be careful about what product you use and where you use it. PerfSorber would be a good product for a room of this size.


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/18969330
> 
> 
> So my 13 x 17 x 7.5 foot room is probably not big enough for diffusion no matter where I am sitting, eh?



I used to think that, and it's the conventional wisdom, but even in a very small room diffusion can add a nice sense of spaciousness. As an experiment I tried adding massive amounts of diffusion to a small room, and I liked the results a lot. This first video explains more about diffusion and lets you hear what it sounds like 6 inches away:

All About Diffusion 


This video lets you hear what microphones pick up at the listening position in a room almost the exact same size as yours:

Hearing is Believing 


--Ethan


----------



## Mark P




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18971830
> 
> 
> I used to think that, and it's the conventional wisdom, but even in a very small room diffusion can add a nice sense of spaciousness. As an experiment I tried adding massive amounts of diffusion to a small room, and I liked the results a lot. This first video explains more about diffusion and lets you hear what it sounds like 6 inches away:
> 
> All About Diffusion
> 
> 
> This video lets you hear what microphones pick up at the listening position in a room almost the exact same size as yours:
> 
> Hearing is Believing
> 
> 
> --Ethan



Very cool Ethan


----------



## Tooj

Due to space limitations, my L/R front speakers are inches from the side wall. Would acoustical treatments on each respective wall be beneficial in any way?


----------



## nathan_h




> Quote:
> Originally Posted by *Tooj* /forum/post/0
> 
> 
> Due to space limitations, my L/R front speakers are inches from the side wall. Would acoustical treatments on each respective wall be beneficial in any way?



Probably.


----------



## Dennis Erskine




> Quote:
> Would acoustical treatments on each respective wall be beneficial in any way?



In this case, more like required...particularily on the boundaries around the speakers.


----------



## Scamps

What software/hardware would I need to be able to create these spiffy response graphs for my theater room? Is there a link or thread to look at?


Thanks.


----------



## Weasel9992




> Quote:
> Originally Posted by *Scamps* /forum/post/18992987
> 
> 
> What software/hardware would I need to be able to create these spiffy response graphs for my theater room? Is there a link or thread to look at?
> 
> 
> Thanks.



Room EQ Wizard.


----------



## A9X-308

 REW


----------



## Ethan Winer




> Quote:
> Originally Posted by *Scamps* /forum/post/18992987
> 
> 
> What software/hardware would I need to be able to create these spiffy response graphs for my theater room? Is there a link or thread to look at?



I made those graph by plotting all the data manually after measuring sine waves. That was before REW was available.







The advice you got here to use REW is correct. This article explains how I use the older ETF software, but all of the explanations apply to REW too:

Using ETF 


--Ethan


----------



## nathan_h




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/18971830
> 
> 
> 
> This video lets you hear what microphones pick up at the listening position in a room almost the exact same size as yours:
> 
> Hearing is Believing
> 
> 
> --Ethan



Interesting.


Not sure that I can sense the increased spaciousness in the recording. The fully treated room is impressive sounding in the video (though a little too utilitarian looking for a home theater!). The untreated/fully treated contrast is instructive and probably even more extreme in person.


What was most interesting: Adding the diffusion to a room that already has good absorption really allowed the bass to be better defined -- which is usually something I associate with trapping rather than diffusion.


Maybe that's because your diffusers ALSO do some bass trapping. But it's interesting that that is what jumped out at me most.


----------



## Ethan Winer

^^^ Yes, the improvement in bass frequency response and ringing is due to the diffusors also working as bass traps. As for increased spaciousness, that's not so much what comes through in the video. It's more _not_ hearing the boxy hollow type sound you'd usually have when recording music playing through loudspeakers.


--Ethan


----------



## velvet396

Came across this brief but cool article on Microsoft's anechoic chamber:
http://gizmodo.com/5372268/microsoft...nd-goes-to-die 


Trampoline floor sounds pretty cool!


----------



## scoobygt68

Anyone ever use insulated sheathing similar to the stuff sold a Lowes or Home Depot? I guess it is made out of "Expanded Polystyrene" so Im not sure what the acoustic asorbtion properties would be. Im thinking about making my own acoustic panels out of it.
http://www.lowes.com/pd_15357-10477-...96_4294937087_


----------



## stgdz

What is the difference between the yellow and pink fiberglass batting? I see the yellow go in the walls and pink go in the ceilings. This isn't the OC703 that I goes on after the drywall either.


----------



## Mark P

I made these 3 diffusors about 3-4 years ago, should I cover them with fabric making them into "cubes" or should I follow the shape? the fabric is called Duck cloth, its cotton and you can see light through it but it is very stiff feeling so Im not sure how transparent it is. Its far from speaker grille cloth.


----------



## ExToker

Mark,

If you want to fabric them and you have a fabric store nearby, take a look at 'broadcloth'.

I saw some yesterday a JoAnn and it looked like it might work good for your app.

Nice mix of transparency, workable structure, and available in lotsa colors.


----------



## nathan_h




> Quote:
> Originally Posted by *scoobygt68* /forum/post/19011208
> 
> 
> Anyone ever use insulated sheathing similar to the stuff sold a Lowes or Home Depot? I guess it is made out of "Expanded Polystyrene" so Im not sure what the acoustic asorbtion properties would be. Im thinking about making my own acoustic panels out of it.





> Quote:
> Originally Posted by *stgdz* /forum/post/19011231
> 
> 
> What is the difference between the yellow and pink fiberglass batting? I see the yellow go in the walls and pink go in the ceilings. This isn't the OC703 that I goes on after the drywall either.


 http://www.bobgolds.com/AbsorptionCoefficients.htm is your friend.


----------



## SierraMikeBravo

Hi Mark,


You can always test any material by placing it in front of a speaker and performing near field tests on it. If it is more than -3dB, it won't work for your purposes. Best wishes!


----------



## FuzzyZipperbaum

I have a sample of GOM, Anchorage. I did the "breath" test and was a bit surprised... the cotton shirt I am wearing had less resistance...am I missing something?


----------



## nathan_h




> Quote:
> Originally Posted by *FuzzyZipperbaum* /forum/post/0
> 
> 
> I have a sample of GOM, Anchorage. I did the "breath" test and was a bit surprised... the cotton shirt I am wearing had less resistance...am I missing something?



Yep your test is right. You dont want to use that in front of speakers and it will diminish high frequency absorption of acoustic panels covered in it. Use 701 for example instead.


----------



## allredp




> Quote:
> Originally Posted by *FuzzyZipperbaum* /forum/post/19073244
> 
> 
> I have a sample of GOM, Anchorage. I did the "breath" test and was a bit surprised... the cotton shirt I am wearing had less resistance...am I missing something?



While Anchorage looks awesome, it doesn't have the acoustic rating that FR701 (I believe) does. If you received samples from Interface Fabrics they will have information on each fabric's properties. Anchorage doesn't claim any acoustic transparency according to the samples I have. It looks cool, but...


----------



## FuzzyZipperbaum

OK, good stuff thanks guys.....so use 701 or even speaker cloth on the false wall... However, does this mean that if I find something close to anchorage at a fabric store I can use it over 703 and base traps? Basically I am asking if I can be more liberal in my selection of fabrics on the areas other than the false wall......THANKS.


----------



## Collo




> Quote:
> Originally Posted by *Mark P* /forum/post/19011361
> 
> 
> I made these 3 diffusors about 3-4 years ago, should I cover them with fabric making them into "cubes" or should I follow the shape?



Adding cloth across the face will increase absorption. Because the pressure at the mouth of each well is different, there is significant airflow across the face of the fins. Adding cloth impedes this airflow.


Following the profile is better, but again there may be an increase in absorption due to the increase in surface roughness.


What the Cox and D'Antonio "bible" has to say... 


They advise against cloth covering, but if you must use it, they suggest it be spaced at least one well width clear of the fin faces.


----------



## Mark P




> Quote:
> Originally Posted by *Collo* /forum/post/19075065
> 
> 
> Adding cloth across the face will increase absorption. Because the pressure at the mouth of each well is different, there is significant airflow across the face of the fins. Adding cloth impedes this airflow.
> 
> 
> Following the profile is better, but again there may be an increase in absorption due to the increase in surface roughness.
> 
> 
> What the Cox and D'Antonio "bible" has to say...
> 
> 
> They advise against cloth covering, but if you must use it, they suggest it be spaced at least one well width clear of the fin faces.



Hmmm, I would have made them a little more towards the pretty side had I known that.........I guess I'll featherfill ( thick primer) and paint the wood ones and fabric the absorbing one


----------



## Weasel9992




> Quote:
> Originally Posted by *allredp* /forum/post/19074228
> 
> 
> While Anchorage looks awesome, it doesn't have the acoustic rating that FR701 (I believe) does. If you received samples from Interface Fabrics they will have information on each fabric's properties. Anchorage doesn't claim any acoustic transparency according to the samples I have. It looks cool, but...



FR701 is class "A" fire rated. Everything posted so far on Anchorage is correct. It's cool-looking and comes in some vivid colors, but FR701 is a better choice acoustically.


----------



## Tooj

Alright, so I made some acoustical panels, but did not make a frame for each. I just wrapped each OC703 sheet in burlap. My original plan was to secure them to the walls with velcro that plan failed mightily.


I am looking for some suggestions on this dilemma. My two current options are:


1) use liquid nails to attach pegboard to the back of each panel and hang like a picture

2) use t-pins straight through the panels and into the wall


I am just looking for any opinions on these two choices or interested in hearing some better options. Thank you.


----------



## Mark P




> Quote:
> Originally Posted by *Tooj* /forum/post/19087230
> 
> 
> Alright, so I made some acoustical panels, but did not make a frame for each. I just wrapped each OC703 sheet in burlap. My original plan was to secure them to the walls with velcro that plan failed mightily.



yeah you have to use pegboard or something to the back of the absorbing material then wrap the fabric over that and stick the velcro to the pegboard, not the fabric and then velcro is more than sufficient. You could still do this if the material was stuck using spray adhesive


----------



## erkq




> Quote:
> Originally Posted by *Tooj* /forum/post/19087230
> 
> 
> Alright, so I made some acoustical panels, but did not make a frame for each. I just wrapped each OC703 sheet in burlap. My original plan was to secure them to the walls with velcro that plan failed mightily.
> 
> 
> I am looking for some suggestions on this dilemma. My two current options are:
> 
> 
> 1) use liquid nails to attach pegboard to the back of each panel and hang like a picture
> 
> 2) use t-pins straight through the panels and into the wall
> 
> 
> I am just looking for any opinions on these two choices or interested in hearing some better options. Thank you.



BURLAP?? Really? Cripes, that's what we used to buy horse feed in







... I can't imagine. I'd say scrap the burlap and use GOM or something similar for your next go-around. And build frames.


----------



## cuzed2




> Quote:
> Originally Posted by *Tooj* /forum/post/19087230
> 
> 
> Alright, so I made some acoustical panels, but did not make a frame for each. I just wrapped each OC703 sheet in burlap. My original plan was to secure them to the walls with velcro that plan failed mightily.
> 
> 
> I am looking for some suggestions on this dilemma. My two current options are:
> 
> 
> 1) use liquid nails to attach pegboard to the back of each panel and hang like a picture
> 
> 2) use t-pins straight through the panels and into the wall
> 
> 
> I am just looking for any opinions on these two choices or interested in hearing some better options. Thank you.



Tooj,


I assume the panels are rather light and at least 1" thick and the backs are not a hard surface?


If so; the following suggestion (may seem simple and crude) worked for me:


Use a pencil to lightly trace out the perimeter outline of your panel in it's desired location onto your wall.


Hopefully you can locate at least one stud behind the drywall inside your outline. Then pound in some extra long finish nails ~2.5". Pound these in until the exposed length is slightly shorter than the thickness of your panels.


Next carefully position the panel in front of the nail heads, and then carefully press the panel to the wall, the exposed head of the finish nail should impale your panel into place, and you are done?


----------



## Tooj

Thanks for the replies. cuzed2, this seems like the easiest choice. I'll give it a try sometime this week.


----------



## cuzed2

Good Luck - let us know if it worked


----------



## Highside

I (may) have the opportunity to purchase some Roxul AFB 1.5" for a great price. My plan would be to double it up to 3" for my acoustic panels.


I've looked at Bob Golds website and see that the numbers for 3" panels are roughly the same regardless of brand/manufacturer.


Is there any reason I would not want to use this particular product?


Rob


----------



## bpape

The Roxul is just fine and personally, my preference in terms of overall quality control from the factory.


Bryan


----------



## Highside




> Quote:
> Originally Posted by *bpape* /forum/post/19108934
> 
> 
> The Roxul is just fine and personally, my preference in terms of overall quality control from the factory.
> 
> 
> Bryan



Thanks Bryan.


On a side note, could I get away with 1.5" panels at the first/ceiling reflections and make up the difference in low absorption with corner chunks of the same material?


What I'm getting at is will there be a big audible difference with 1.5" panels vs. 2" panels at the first reflections, all else being equal?


----------



## Weasel9992




> Quote:
> Originally Posted by *Highside* /forum/post/19109197
> 
> 
> On a side note, could I get away with 1.5" panels at the first/ceiling reflections and make up the difference in low absorption with corner chunks of the same material?



Yes...that'll work just fine.



> Quote:
> Originally Posted by *Highside* /forum/post/19109197
> 
> 
> What I'm getting at is will there be a big audible difference with 1.5" panels vs. 2" panels at the first reflections, all else being equal?



Not a huge difference.


----------



## doublewing11

Having difficult time finding 1" diffusors.......these are the only two I've found:


RPG Bad Panels which are not true diffusors


or


Auralex which are 1" plastic step wedges.


Are there other 1" thick diffusors that can be recommended?


Thanks


----------



## pepar




> Quote:
> Originally Posted by *doublewing11* /forum/post/19127866
> 
> 
> Having difficult time finding 1" diffusors.......these are the only two I've found:
> 
> 
> RPG Bad Panels which are not true diffusors
> 
> 
> or
> 
> 
> Auralex which are 1" plastic step wedges.
> 
> 
> Are there other 1" thick diffusors that can be recommended?
> 
> 
> Thanks



One inch is not very deep for a diffusor ... or an absorber.


----------



## Weasel9992




> Quote:
> Originally Posted by *pepar* /forum/post/19127885
> 
> 
> One inch is not very deep for a diffusor ... or an absorber.



Right. Why do you want a 1" diffuser anyway?


----------



## pepar




> Quote:
> Originally Posted by *Weasel9992* /forum/post/19131334
> 
> 
> Right. Why do you want a 1" diffuser anyway?



I'm sure that it has something to do with aesthetics.


----------



## kevinzoe




> Quote:
> Originally Posted by *doublewing11* /forum/post/19127866
> 
> 
> Having difficult time finding 1" diffusors.......these are the only two I've found:
> 
> 
> RPG Bad Panels which are not true diffusors
> 
> 
> or
> 
> 
> Auralex which are 1" plastic step wedges.
> 
> 
> Are there other 1" thick diffusors that can be recommended?
> 
> 
> Thanks




Doublewing11 - have you considered RPG's Flutter Free product found here: http://www.rpginc.com/products/flutterfree/index.htm ? It is 1 1/16" deep which would appear to meet your 1"depth requirement. However, and this might be a deal breaker for you, it really is only effective over 2 octaves from 5kHz-20kHz as per RPG's calculated diffusion coefficient claims.


If all you want to do is kill some flutter echo's then this product will likely suffice as flutter echos tend to be more easily heard in the upper frequencies. But, if you wish to add spaciousness, source width and listener envelopment, then a 1" depth is totally inadequate; aim for 8"-12" or deeper yet to bring the effectiveness down to your room's transition (or Schroeder) frequency, which is likely about 300Hz for residential rooms.


Let us know what you're thinking or planning and perhaps others will chime in with sage advice.


----------



## doublewing11




> Quote:
> Originally Posted by *pepar* /forum/post/19131371
> 
> 
> I'm sure that it has something to do with aesthetics.



Thanks for replying.........


You hit the nail on the head......


Organizing products for fabric wall............can increase the thickness of back/side wall diffusor treatments needed near seating..........just trying to find products consistent in thickness to the treatments I've purchased for the front of the room.


I've found two inch thick diffusors that would suffice........but are not the same thickness as the one inch absorbers up front.


----------



## doublewing11




> Quote:
> Originally Posted by *kevinzoe* /forum/post/19133326
> 
> 
> Doublewing11 - have you considered RPG's Flutter Free product found here: http://www.rpginc.com/products/flutterfree/index.htm ? It is 1 1/16" deep which would appear to meet your 1"depth requirement. However, and this might be a deal breaker for you, it really is only effective over 2 octaves from 5kHz-20kHz as per RPG's calculated diffusion coefficient claims.
> 
> 
> If all you want to do is kill some flutter echo's then this product will likely suffice as flutter echos tend to be more easily heard in the upper frequencies. *But, if you wish to add spaciousness, source width and listener envelopment, then a 1" depth is totally inadequate; aim for 8"-12" or deeper yet to bring the effectiveness down to your room's transition (or Schroeder) frequency, which is likely about 300Hz for residential rooms*.
> 
> 
> Let us know what you're thinking or planning and perhaps others will chime in with sage advice.



There is the goal...............ie. spaciousness, and envelopment for two rows seating for eight.


The wife factor plays in ........therefore, 8-12 inches would not work due to aesthetics! Any suggestions?


I'm all ears......


----------



## kevinzoe




> Quote:
> Originally Posted by *doublewing11* /forum/post/19134159
> 
> 
> There is the goal...............ie. spaciousness, and envelopment for two rows seating for eight.
> 
> 
> The wife factor plays in ........therefore, 8-12 inches would not work due to aesthetics! Any suggestions?
> 
> 
> I'm all ears......




Get rid of your main restriction - the wife!







(Just kidding.)


Have you considered rearranging the seating so that you have three rows of seats - 2 in row one and 3 in rows two and three, thereby allowing more side wall room? Or would this configuration put the back row seats too close to the back wall?


Another thought . . . can you open the drywall to insert a diffuser so that the product's depth is using the wall cavity to reduce the amount that it extends into the room? This way you aren't limited to 1" diffusers which is really not the right way to go.


A semi-circular architectural-looking pillar (i.e. hemi-cylindrical diffuser or polyfuser) will act as a diffuser splaying the sound waves in an approx 120degree arc. (PM me if you want pictures of the ones I've built.) The RPG BAD panels come in a 'round' version and would work. You can build them yourself by buying a Sonotube that come in many different diameters and putting a nice wood panel over it and stain/polyurethane it to match your wife's asthetic eye . . .


What about using a larger room elsewhere in the home? Other than that I'm fresh out of ideas given the 1" depth restriction.


----------



## pepar

Or use 2" everywhere for consistent thickness. Looks are important but if what you install doesn't work properly ...


----------



## SierraMikeBravo

Hi doublewing,


You may wish to check out Quest Acoustical Interiors products as well. I have said this before and I'll say it again, IMHO, RPG is best utilized in a commercial environment. They just don't produce products that are "home friendly" nor truely customizable. While they do work (in some...not all applications) they are quite unsightly. Quest products will do the same thing as RPG products but will be far more wife friendly if incorporated properly and you won't have to cut into any walls to accomodate other products...which causes a host of other problems.


Regarding your spaciousness/envelopment requirement, treatment will help to some degree, but there are several additional factors that come into play here such as proper timing and speaker alignment, speaker placement, speaker type can also be a factor here, and system/room layout. Hope this helps! Best wishes!


----------



## doublewing11




> Quote:
> Originally Posted by *kevinzoe* /forum/post/19134596
> 
> 
> Get rid of your main restriction - the wife!
> 
> 
> 
> 
> 
> 
> 
> (Just kidding.)
> 
> 
> Have you considered rearranging the seating so that you have three rows of seats - 2 in row one and 3 in rows two and three, thereby allowing more side wall room? Or would this configuration put the back row seats too close to the back wall?
> 
> 
> Another thought . . . can you open the drywall to insert a diffuser so that the product's depth is using the wall cavity to reduce the amount that it extends into the room? This way you aren't limited to 1" diffusers which is really not the right way to go.
> 
> 
> A semi-circular architectural-looking pillar (i.e. hemi-cylindrical diffuser or polyfuser) will act as a diffuser splaying the sound waves in an approx 120degree arc. (PM me if you want pictures of the ones I've built.) The RPG BAD panels come in a 'round' version and would work. You can build them yourself by buying a Sonotube that come in many different diameters and putting a nice wood panel over it and stain/polyurethane it to match your wife's asthetic eye . . .
> 
> 
> What about using a larger room elsewhere in the home? Other than that I'm fresh out of ideas given the 1" depth restriction.



Get rid of my BEST friend for the last twenty-five years? Not a chance!










Since this is a new construction, nothing is set in stone ...........yet time is ticking away. Ground breaks in November as my home will be part of a "Tour of homes" show the first of June. The home plans are set, but the dedicated theater can still use some tweaking........


----------



## doublewing11




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19137985
> 
> 
> Hi doublewing,
> 
> 
> You may wish to check out Quest Acoustical Interiors products as well. I have said this before and I'll say it again, IMHO, RPG is best utilized in a commercial environment. They just don't produce products that are "home friendly" nor truely customizable. While they do work (in some...not all applications) they are quite unsightly. Quest products will do the same thing as RPG products but will be far more wife friendly if incorporated properly and you won't have to cut into any walls to accomodate other products...which causes a host of other problems.
> 
> 
> Regarding your spaciousness/envelopment requirement, treatment will help to some degree, but there are several additional factors that come into play here such as proper timing and speaker alignment, speaker placement, speaker type can also be a factor here, and system/room layout. Hope this helps! Best wishes!



Thanks for the input SMB..........


Your input several months ago literally stopped me in my tracks...........since then, your suggestions have taken me in another direction.


I'm an independently minded person and really wanted to get involved with putting this theater together. I'm close to understanding what I want/need in terms of budget and aesthetics.....and will summon the help of a designer to put it together once I'm 100% sure of my goals and path of implementation.


Yeah, I know............room first, but can't help myself in regard to audio equipment. Would love to audition the Procella brand, but with that said, am heavily leaning toward either Aerial (LR5/SR3) or Triad (Gold Monitors/Gold surrounds) for implementation.


One step at a time...........................


----------



## Dennis Erskine

All three of these speakers you've noted are excellent and happen to fall on my favorites list. The Procella, however, uses a compression driver which will provide better HF performance over greater seating distances than Aerial/Triad. Within reasonable limits a determining factor between Procella and Aerial/Triad could be seating distances.


SMB mentioned Quest Acoustical Interiors ( www.QuestAI.com ). They have a unique two inch product marketed under the name PerfSorber. It is an excellent absorber and diffusor which works better (and measures better) than you'd expect from a 2" material. We've used that in several high performance projects to excellent results. (One of which was the THX Certified room in New Jersey.) [NOTE: PerfSorber is not available except from QuestAI ... there is a fresh patent on it.]


----------



## doublewing11




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19139492
> 
> 
> All three of these speakers you've noted are excellent and happen to fall on my favorites list. The Procella, however, uses a compression driver which will provide better HF performance over greater seating distances than Aerial/Triad. Within reasonable limits a determining factor between Procella and Aerial/Triad could be seating distances.
> 
> 
> SMB mentioned Quest Acoustical Interiors ( www.QuestAI.com ). They have a unique two inch product marketed under the name PerfSorber. It is an excellent absorber and diffusor which works better (and measures better) than you'd expect from a 2" material. We've used that in several high performance projects to excellent results. (One of which was the THX Certified room in New Jersey.) [NOTE: PerfSorber is not available except from QuestAI ... there is a fresh patent on it.]



Thanks for the comments Dennis.............


I might be naive', but without a listen the Procella products do scare me a tad bit............I'm still hemorrhaging from a Klipsch audition. Horn or waveguide tweets............ they are all the same to me ie. loaded horns. I will defer to the experts on deciphering the differences.


Thanks for the Quest Acoustic Interiors url............not as much information as the MSR site, but I will take your word as gospel in regard to product performance and will contact dealer in Washington State.


This product search/research is a pain, but hopefully in the future it pays off. Sad but true, there are no real affordable turnkey solutions for home theater construction in Oregon..........if I was in California, different story.


----------



## Dennis Erskine

Largely the problem with horns is they can take your head off if you're sitting too close to them. It can easily be a seating distance problem.


If you're coming to CEDIA Expo, Procella will have a life demo running.


----------



## A9X-308




> Quote:
> Originally Posted by *doublewing11* /forum/post/19140882
> 
> 
> Horn or waveguide tweets............ they are all the same to me ie. loaded horns.



No they are not.


----------



## doublewing11




> Quote:
> Originally Posted by *A9X-308* /forum/post/19141187
> 
> 
> No they are not.



Ok..............


Please elaborate............


Though I'm not an expert in the audio/video realm.........I do have an extensive background in both mathematics and physics which helps in understanding underlying principles and properties.


If I'm missing something, I'm all ears as I want to know/learn the difference.



Btw, a note to others..................what are the underlying differences in overall quality and execution between the two acoustic distributors Quest and MSR?


Thanks


----------



## A9X-308




> Quote:
> Originally Posted by *doublewing11* /forum/post/19141765
> 
> 
> Ok..............
> 
> 
> Please elaborate............
> 
> 
> Though I'm not an expert in the audio/video realm.........I do have an extensive background in both mathematics and physics which helps in understanding underlying principles and properties.
> 
> 
> If I'm missing something, I'm all ears as I want to know/learn the difference.



All the information is out there if you choose to look for it. A simple equation describing a flare's shape barely begins to define how it will sound. You need to study the drivers as well and how they interact to form a system and how that interfaces with a room. You have a lot of research ahead of you.


My earlier response was akin to: because you have heard one implementation of horn loaded drivers (tractrix flare with cheap CDs) then they all sound the same. I have owned several Klipsch models and heard more and they are far from the best representations of their type.


----------



## doublewing11




> Quote:
> Originally Posted by *A9X-308* /forum/post/19142845
> 
> 
> All the information is out there if you choose to look for it. A simple equation describing a flare's shape barely begins to define how it will sound. You need to study the drivers as well and how they interact to form a system and how that interfaces with a room. You have a lot of research ahead of you.
> 
> *My earlier response was akin to: because you have heard one implementation of horn loaded drivers (tractrix flare with cheap CDs) then they all sound the same*. I have owned several Klipsch models and heard more and they are far from the best representations of their type.



Never thought of the Pallidiums worthy of playing cheap CDs.........


Well...........I guess I'm guilty of not liking the Klipsch sound...........but am open minded enough to give other similar designs a shot.


Guilty as charged.......btw, I enjoy ribbons and fabric dome tweets.......


----------



## A9X-308

CD=compression driver


Not hear the Palladiums myself, but almost everything else.


----------



## Dennis Erskine




> Quote:
> Quest and MSR



They both produce high quality products.


----------



## tony123

I couldn't figure out a good place to post this, hope I got it right.


My room is 32x17.5x9' and I have been using it while under construction. For the last year one of my long walls has been simply 5/8" sheetrock on standard studded wall.


I'm using two Danley DTS10's and have actually been a little displeased with performance. Over the last few days I got R13 placed into that entire long wall. Since this change, my wife and I have both noticed improved sub performance. It's all a bit tighter, more percussive and extension seems improved.


Are we imagining this? or is there some reasoning behind our findings? With my limited understanding, could it be that the bare sheetrock wall just let the sub frequencies right out into the rest of the basement? Maybe now the sheetrock plus R13 is helping to keep the energy in the theater a bit better? Would adding the sheetrock on the outside of that wall help even more?


----------



## Dennis Erskine

When you're outside the room, can you hear the sub? There you go. The insulation is doing next to nothing as far as sound transmission outside the room. The insulation would be reducing resonance inside the wall cavities which is helpful.


----------



## tony123

I'm not trying to accomplish sound isolation. It means nothing in my arrangement. But I do welcome any acoustic benefit inside the room.


If I didn't know better, the subs are reacting to this as if prior to insulation they were trying to pressurise the entire 2000sf basement.


I would not have guessed that resonance in the wall played this large a role.


Thanks for your input Dennis.


----------



## Dan Woodruff

Tony,


I don't mean to oversimplify or to speak for Dennis as he and the other pros can explain this far better than I can.


What is going on is, as you said, your subs are trying to fill the entire basement. This is because the low tones produced by your subs are passing straight through the walls. The insulation you installed did very little to stop this but as you now know, it is dampening the resonance within the wall. Although there are great benefits outside the room by isolation, what is often understated are the benefits inside the room with isolation. The most accepted and easiest way to do this "sound containment" is double layers of sheet rock inside the room. You will also hear improvement when you install the sheet rock on the outside of the wall.


Since you had only one layer of sheetrock over the studs inside the room and the other side was open, you essentially had a giant drum the subs were striking with each note. This was producing the resonance you had and still have to some extent. Until the wall is "rigid", this resonance will still occur to some degree.


For now, I would concentrate on installing the sheet rock in the hallway to close the wall. I could be wrong and the pros can lead you better than I but at the moment, it's probably where you will get the best "bang" for the buck.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/19212854
> 
> 
> Since you had only one layer of sheetrock over the studs inside the room and the other side was open, you essentially had a giant drum ... Until the wall is "rigid", this resonance will still occur to some degree.



Yes, though there's more going on as well. An un-damped sheet rock wall does resonate and ring. But when the cavity is stuffed with insulation that sympathetic resonance is damped. So you actually get some bass trapping / absorption. But a large room like that needs more bass trapping inside the room to get even tighter and flatter bass.


--Ethan


----------



## tony123

Thanks Dan and Ethan. The "drum" theory makes alot of sense. It may be a few months before I can close in that wall completely, but I look forward to any additional benefit.










Ethan, I do have the typical OC703 triangular corner traps on two wall to wall corners in the front of the room (floor to ceiling). I recognize that this is a small dent in what the room size demands. My final treatment plan will include the wall/ceiling connection at the front and rear walls. Beyond that I would be making aesthetic sacrifices that I don't want to make.


BTW, Ethan I've enjoyed your online videos time and time again. Thank you.


----------



## Ethan Winer

Thanks Tony. I'm in the final throes of a third music video now, though it will _not_ show 20 Ethans playing instruments!










--Ethan


----------



## pepar

At CEDIA one of the chaps at the THX/Procella Sound demo recommended a "baffle wall" be built so that wall-mounted speakers be as flush as possible and cutouts be 1" larger than the speaker and the 1" gap filled with foam. He said that there would be a 6dB gain by doing this. Is there any truth to this?


Jeff


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19252396
> 
> 
> At CEDIA one of the chaps at the THX/Procella Sound demo recommended a "baffle wall" be built so that wall-mounted speakers be as flush as possible and cutouts be 1" larger than the speaker and the 1" gap filled with foam. He said that there would be a 6dB gain by doing this. Is there any truth to this?
> 
> 
> Jeff



I don't know about the 6dB gain, but this is a great idea for controlling sound waves that follow the speaker baffle surface until they reflect off something, causing out-of phase reflections. DIY speaker builders often put absorptive materials around speakers, especially the tweeter. This is just doing it for the whole speaker.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/19253051
> 
> 
> I don't know about the 6dB gain, but this is a great idea for controlling sound waves that follow the speaker baffle surface until they reflect off something, causing out-of phase reflections. DIY speaker builders often put absorptive materials around speakers, especially the tweeter. This is just doing it for the whole speaker.



That was indeed one of the benefits as he described it; sound that would follow or be radiated by the cabinet up, down, to the side or rear would be eliminated. The THX/Procella demo, with the baffle wall, was the second best demo we heard. Harman's demo had free-standing speakers and was third. Wisdom Audio's demo was the best and theirs had in-wall speakers. I'm not saying that that was the variable that made the difference, just observing that the two best sounding demos had "flushed" speakers.


Jeff


----------



## SierraMikeBravo

Yes Pepar, there is truth to this, and Audyssey has nothing to do with it!
 






By flush mounting, you increase the sensitivity of the speaker, thereby increasing the ouput of the speaker given the same amount of wattage. So, if you increase the sensitivity by 6 dB by flush mounting, you also increase the efficiency and the ouput is equal to the increase in efficiency....therefore an output increase by 6 dB. This, of course, depends on a perfect world, and there are other factors which may cause actual values to fluctuate, etc, etc. I am sure we will here the faint whine of circular saws buzzing away way past midnight tonight as everyone rushes out to build a baffle wall. If only Home Depot was open 24 hours. P.S. Gotta razz you on the Audyssey thing now and again.









http://www.thx.com/professional/cine...d-baffle-wall/


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19254395
> 
> 
> Yes Pepar, there is truth to this, and Audyssey has nothing to do with it!
> 
> 
> 
> 
> 
> 
> 
> By flush mounting, you increase the sensitivity of the speaker, thereby increasing the ouput of the speaker given the same amount of wattage. So, if you increase the sensitivity by 6 dB by flush mounting, you also increase the efficiency and the ouput is equal to the increase in efficiency....therefore an output increase by 6 dB. This, of course, depends on a perfect world, and there are other factors which may cause actual values to fluctuate, etc, etc. I am sure we will here the faint whine of circular saws buzzing away way past midnight tonight as everyone rushes out to build a baffle wall. If only Home Depot was open 24 hours. P.S. Gotta razz you on the Audyssey thing now and again.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.thx.com/professional/cine...d-baffle-wall/



The THX link seems to be related to a movie theater, but I suppose it scales down to a home theater. That I heard it in a small room seems to confirm that. A 6dB increase in output is HUGE! And nearly free.


Should the baffle wall be covered with diffusion? It seems odd to leave it untreated.


I deserve a shot every now and then on my affinity for Audyssey.


Jeff


----------



## SierraMikeBravo

Treat with absorption the same way you would with any front wall. How much absorption...well I'll keep that one under wraps. A girl has to have some secrets!










Commercial THX theater...home THX theater...what's the difference? Best wishes!


----------



## erkq




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19254596
> 
> 
> Commercial THX theater...home THX theater...what's the difference? Best wishes!



Room size, of course. But for purposes of this discussion it probably doesn't matter.


So 6dB is 4x the power. Is this really true? As pepar says, that is huge.


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19254596
> 
> 
> Treat with absorption the same way you would with any front wall. How much absorption...well I'll keep that one under wraps. A girl has to have some secrets!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Commercial THX theater...home THX theater...what's the difference? Best wishes!



Thanks, Shawn.


Jeff


----------



## bpape




> Quote:
> Originally Posted by *erkq* /forum/post/19254684
> 
> 
> Room size, of course. But for purposes of this discussion it probably doesn't matter.
> 
> 
> So 6dB is 4x the power. Is this really true? As pepar says, that is huge.



3db increase in loudness requires 2x the power. 6db, double it again.



Bryan


----------



## LarryChanin




> Quote:
> Originally Posted by *pepar* /forum/post/19253406
> 
> 
> That was indeed one of the benefits as he described it; sound that would follow or be radiated by the cabinet up, down, to the side or rear would be eliminated. The THX/Procella demo, with the baffle wall, was the second best demo we heard. Harman's demo had free-standing speakers and was third. Wisdom Audio's demo was the best and theirs had in-wall speakers. I'm not saying that that was the variable that made the difference, just observing that the two best sounding demos had "flushed" speakers.
> 
> 
> Jeff





> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19254395
> 
> 
> Yes Pepar, there is truth to this, and Audyssey has nothing to do with it!
> 
> 
> 
> 
> 
> 
> 
> By flush mounting, you increase the sensitivity of the speaker, thereby increasing the ouput of the speaker given the same amount of wattage. So, if you increase the sensitivity by 6 dB by flush mounting, you also increase the efficiency and the ouput is equal to the increase in efficiency....therefore an output increase by 6 dB. This, of course, depends on a perfect world, and there are other factors which may cause actual values to fluctuate, etc, etc. I am sure we will here the faint whine of circular saws buzzing away way past midnight tonight as everyone rushes out to build a baffle wall. If only Home Depot was open 24 hours. P.S. Gotta razz you on the Audyssey thing now and again.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.thx.com/professional/cine...d-baffle-wall/





> Quote:
> Originally Posted by *erkq* /forum/post/19254684
> 
> 
> Room size, of course. But for purposes of this discussion it probably doesn't matter.
> 
> 
> So 6dB is 4x the power. Is this really true? As pepar says, that is huge.



Hi,


Yes, in an ideal situation with an omnidirectional source and perfectly reflecting boundaries, flush mounting results in a 6 dB increase in SPL. Dr. Toole discusses this on page 184 of his book, Sound Reproduction. Likewise, positioning the source at a bi-corner produces a 12 dB increase in SPL and positioning the source at a tri-corner results in an 18 dB increase in SPL.



> Quote:
> The technical description of full spherical, omnidirectional radiation is that the sound source "sees" a solid angle of 4 Pi steradians. It is a full space-a "free field" with no surfaces to reflect or redirect the radiated sound. Placing the sound source on or in a large plane surface reduces the solid angle into which the sound radiates by half-2 Pi steradians-a half space. Energy that would have traveled into the rear hemiphere is reflected forward; there is a reflected acoustical "image" of the source. Additional surfaces, positioned at right angles, reduce the solid angle by half, to Pi steradians and then to Pi/2 steradians. The number of reflected images increases correspondingly. It can be seen that the sound pressure level, measured at a constant distance from the sound source in these otherwise reflection-free circumstances, goes up 6 dB for each halving of the solid angle.



On page 191 Dr. Toole specifically discusses the situation of mounting an on-wall speaker inside a cavity, both with and without fiberglass to fill the gap between the speaker and cavity. Inserting the fiberglass does improve the response due to the reduction in diffraction effects. However, flush mounting the same speaker, i.e. turning it into an in-wall speaker, provides an even smoother response than the fiberglass filled cavity. In all three of these situations we are dealing with a 2 Pi steradian solid angle so the gain of 6 dB is apparent, but as stated the real-world frequency responses are not the same.


Larry


EDIT:

It should be noted that these +6 dB increases in SPL are with reference to the 4 Pi steradians solid angle situation, which is the same as saying a comparison to a situation with no boundaries, or basically compared to outdoors.


----------



## SUBnet192

Any input on where to get GOM FR701? I'm in Canada. I looked at one reseller but the online form didnt allow for Canadian addresses...


----------



## erkq




> Quote:
> Originally Posted by *SUBnet192* /forum/post/19269837
> 
> 
> Any input on where to get GOM FR701? I'm in Canada. I looked at one reseller but the online form didnt allow for Canadian addresses...



Was that Fabricmate? I would think they'd ship to Canada, but I don't know.


----------



## Dennis Erskine

Back to 1" material, diffusion and the Quest PerfSorber product ... here's what can be done with 1"

 

PerfSorber.pdf 126.21484375k . file


----------



## allredp




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19272093
> 
> 
> Back to 1" material, diffusion and the Quest PerfSorber product ... here's what can be done with 1"



Those look pretty cool - how much do these cost? And in what sizes do they come?


----------



## Dennis Erskine

48"x96"

Cost depends on size, 1" or 2", and fabric covered or not.


----------



## Dennis Erskine

...and, here's what you can do in 2" (data from Riverbank). By-the-way, when you're buying this stuff (other than just normal fiberglass panels), get the certified lab test results to make certain you're really getting the claimed performance.

 

QSorber.pdf 25.1640625k . file


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> 48"x96"
> 
> Cost depends on size, 1" or 2", and fabric covered or not.



A quick google search didn't produce any cost range data, regardless of size. Perhaps there is no direct sales to end users?


----------



## Dennis Erskine

That would be correct.


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19279156
> 
> 
> That would be correct.



Ah, well, the search for a consumer product like that continues, then.


----------



## pepar

No surprises there.


----------



## Dennis Erskine

Search for a consumer product? It is a consumer product. You just cannot purchase directly from the manufacturer. You refuse to drive a car because you cannot purchase it directly from the manufacturer?


----------



## pepar

Purchasing a car these days is a whole lot more transparent and consumer-friendly than deciding on and purchasing acoustical treatments or, for that matter, the services of an acoustician/theater designer. For the former, the prices are known as is what the buyer is getting for his money. For the latter, comparative testing is non-existent.


There is no correlation between performance of mutual funds and whether they are load or no-load. And I doubt that there is any correlation between performance and whether an acoustical treatment is sold as a commodity and one that is tightly controlled and sold only through gurus.


I should add that everybody has a right to make a living and even succeed wildly if they can. But caveat emptor.


Jeff


----------



## Dennis Erskine

Jeff:


Good points. None-the-less, Caveat Emptor does apply. In the case of the Quest products the certified lab testing results are available (some have been posted here). If one is looking for simple 1 or 2" fiberglass panels, it is possible they'll do better from a price perspective by shopping online vendors. In the case of Quest, the vast majority of their products are engineered products. Several factors come into play from the perspective of the manufacturer. These include individuals purchasing certain products and then noting they didn't do such and such which, in the end turns out to be, the use of the inappropriate product for the problem, incorrect placement or mounting of the product, or use of too much of the product (yes it happens).


Controlled distribution certainly doesn't make the product perform better (or worse); but, at least there is a qualified individual working with the end user to see that the end user is getting whatever it is that is best suited for their specific application. Good bad or indifferent, there are very few items in this industry which are available directly from the manufacturer. (Controlled distribution, btw, doesn't imply controlled pricing ... and here in the U.S. that has to be true.)



> Quote:
> For the latter, comparative testing is non-existent.



Sad but true, that's why I've stated before, you really need to get the third party certified lab test results if you're buying a product for its acoustical properties. (In the case of the Quest materials posted here, the lab test results are included.)


Actually, truth be told, I believe the consumer is better off with the controlled distribution or dealer network model. If the manufacturer had to deal with the entire universe of end users calling up for questions, getting pricing, placing small orders, whatever, that manufacturer would have to have the staff available to handle it ... that overhead would be reflected in the price. By the same token you'd have one, and only one, source for a specific product. In the dealer model, that overhead cost is reflected in their offering price (granted they want a profit as well) but offsetting that is price competition due to multiple sources of supply. I don't think the dealer's profit margin affects the end pricing model that much either. Profits tend to be calculated as percentages thus as the overhead of the manufacturer goes up, the profit percentage may remain the same but the raw dollars increase. Oh, well, so much for this topic .... back to acoustics please (if I had wanted to be an economist, I would have taken two semesters of econometrics ... yuk.)


----------



## nathan_h

I value the expert consulting I have paid for, in setting up my theater.


In most situations, I like to do research into products and services before paying for (or even using for free) an expert's time. In this case, with this product, I couldn't find any of the basic information about use cases and pricing structures online, in order to know whether it might be right for me to pursue it a little more. I am window shopping, at this point.


----------



## Dennis Erskine

Well, I can provide you pricing information (offline) if you'd wish.


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> Well, I can provide you pricing information (offline) if you'd wish.



Sure, please send me a PM.


----------



## AnthemAVM

I found these up for sale around me, and was wondering if they might help my new room in the house I close escrow in a month on? Are these like TriTraps, or specific to a specific tune?


Four 4-ft. tall ACS bass tube traps. Two are 8/9 inches diameter, and two are 11/12 inches diameter. Fabric covered tubes in a beige tweed. Perfect condition. Clean and tight. Stack them or place them individually around your space. Tune your music room - condition your acoustics! These are priced from $498-$526 EACH new!





















Thanks


----------



## Ethan Winer

IMO, small diameter tubes like those are not very useful. They're just not large enough to absorb to low enough frequencies. However, tube traps that are 20 inches in diameter can work very well.


--Ethan


----------



## erkq




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19287212
> 
> 
> IMO, small diameter tubes like those are not very useful. They're just not large enough to absorb to low enough frequencies. However, tube traps that are 20 inches in diameter can work very well.
> 
> 
> --Ethan



Are 20" tube traps equivalent to filling room corners with triangles of OC703 type material? Better? Worse? It would be a lot simpler.


----------



## AnthemAVM




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19287212
> 
> 
> IMO, small diameter tubes like those are not very useful. They're just not large enough to absorb to low enough frequencies. However, tube traps that are 20 inches in diameter can work very well.
> 
> 
> --Ethan



Thanks Ethan,


I will keep looking.


----------



## Ethan Winer




> Quote:
> Originally Posted by *erkq* /forum/post/19287389
> 
> 
> Are 20" tube traps equivalent to filling room corners with triangles of OC703 type material? Better? Worse?



It depends on a lot of things, such as the wall thickness in the tube traps. Generally, bass trapping is all about total surface coverage, assuming material thick enough for the job. That's why I always remind people that rectangle rooms have 12 corners, not just four. The more total corner surface you treat, the better. Always.


--Ethan


----------



## Dennis Erskine

Don't get anything unless you can get the certified lab test results so you know what you are getting.


----------



## audhunt

Hey guys...looking for a solution. I am in the process of putting bass traps in the corners behind the screen wall. The issue I have is this. All of the duct board I have found in Houston TX has facing due to the heat here. what are my options?


Thanks,


----------



## pepar




> Quote:
> Originally Posted by *audhunt* /forum/post/19308471
> 
> 
> Hey guys...looking for a solution. I am in the process of putting bass traps in the corners behind the screen wall. The issue I have is this. All of the duct board I have found in Houston TX has facing due to the heat here. what are my options?
> 
> 
> Thanks,



Owens Corning 703, no kraft paper or "facing" is recommended. Check here.

http://winroc.com/branch-locator-spi...php?id_prov=53


----------



## Mark P

or tear the kraft paper off


----------



## audhunt

Thanks for the quick link really appreciate it. Next question is the size triangle 1'X1'? at $1.20 sq ft the stuff is preety darn expensive


----------



## pepar




> Quote:
> Originally Posted by *audhunt* /forum/post/19308662
> 
> 
> Thanks for the quick link really appreciate it. Next question is the size triangle 1'X1'? at $1.20 sq ft the stuff is preety darn expensive



I bought the 24" x 48" x 2" 703 at about $75 for TWELVE sheets. From each sheet, I made eight 17" x 17" x 24" triangles.


That was 3-4 years ago...


Jeff


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *pepar* /forum/post/19308594
> 
> 
> Owens Corning 703, no kraft paper or "facing" is recommended. Check here.
> 
> http://winroc.com/branch-locator-spi...php?id_prov=53



Wouldn't that (whether to remove the kraft paper or not) depend on whether your room needs additional mid/high absorption or not?


----------



## pepar




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19309487
> 
> 
> Wouldn't that (whether to remove the kraft paper or not) depend on whether your room needs additional mid/high absorption or not?



Crosssectionally .. is that a word? .., as SSC bass traps are constructed, the paper won't make any difference in mid- or high-frequency absorption.


Of course, I might have incorrectly inferred that the context *was* SSC bass traps. If the OP was referring to a sheet straddling the corner , then you are correct.


Jeff


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *pepar* /forum/post/19309675
> 
> 
> Crosssectionally .. is that a word? .., as SSC bass traps are constructed, the paper won't make any difference in mid- or high-frequency absorption.



Ah gotcha, I wasn't thinking superchunk.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19309487
> 
> 
> Wouldn't that (whether to remove the kraft paper or not) depend on whether your room needs additional mid/high absorption or not?



Yes, exactly. For corner bass traps, having a facing is very useful. It increases LF absorption substantially while reducing mid and high frequency absorption to avoid making a room totally dead sounding. Of course, at reflection points and a few other key places, no facing is needed.


--Ethan


----------



## Antripodean

In a couple of weeks I will have 6 acoustic panels - CSR Ultratel glass fibre Acoustic Panels. These are made from double layer 48kg fibreglass batts and are 100mm thick, 600mm wide and 1800mm high and there are 6 of them. They work as broadband absorbers and can also be stacked for corner bass traps.


There will be two Bass Boxes in each corner (beside the kitchen opening)

Bass box = Width: 60 cm X Depth: 70 cm X Height: 70 cm

Dual opposed 15" drivers so one end is firing into the corner.

Frequency up to 320Hz from the bass boxes. Higher frequencies from a horn.


There is 180+ cm between the front 'wall' (opening to kitchen) and mantlepiece so I can lay them on their side there. The ceiling is pretty high! (~11')


The room will be used for HT and music. The fixed Xscreen (200cm) drops down from above the kitchen opening (projector on the rear wall above the sofa).


Any suggestions on where best to place them in my room?

 

Room Acoustics dimensions.pdf 13.7685546875k . file


----------



## KERMIE

Ethan,


I downloaded and ran your test tone cd yesterday.


I set pink noise to 70 prior to the test.


Here are some findings:


A. I can get fairly flat from 24Hz to 56Hz at 73db.


B. Then a slow decline at 1Hz intervals from 57Hz to 72Hz a drop of about 13db to 60db.


C. From 73Hz an incline up to flat at 80hz, it stays that way to about 115Hz bouncing between 70-72 db.


D. From 116HZ there is a steady decline until it bottoms out at 50db at 158Hz.


E. Then I have a steady incline up to 170Hz..then flat until 210Hz.


F. at 211Hz it starts to decline down to 52db at the 221Hz.


G. It then zig zags with slow inclines and declines at these levels:


62db at 230Hz

52db at 233Hz

64db at 242Hz

52db at 255Hz

72db at 262Hz all the way to 300Hz


Sorry I dont have a picture of the plots but what is the best way to handle some of these valleys?


My room is roughly 17.5 x 12 x 7.5


Thank you for your help and the test tone cd is great.


K.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Antripodean* /forum/post/19325963
> 
> 
> Any suggestions on where best to place them in my room?



See this:

* Acoustic Basics *


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *KERMIE* /forum/post/19330180
> 
> 
> Here are some findings:



That's quite typical, and the solution is bass traps. The more traps you have, the closer you'll get to a flat response. Yes, it's that simple.


--Ethan


----------



## SierraMikeBravo

A different and perhaps a more sightly and economical approach would be to use an appropriate parametric EQ. Also, you need to determine just what is causing the "dip" to occur? Is it modes (unlikely if it is that wide) or is it something in the room that is causing a suckout, or is it something else, SBIR, speaker/listener positioning? This should be determined first if you want to treat it correctly. Best wishes!


----------



## Antripodean




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19330465
> 
> 
> See this:
> 
> * Acoustic Basics *
> 
> 
> --Ethan



Thanks, I have your site bookmarked.


----------



## erkq




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19330947
> 
> 
> A different and perhaps a more sightly and economical approach would be to use an appropriate parametric EQ.



I hope I can quote from a non-subscription site. The fallacy of this very well explained by Ethan:


"Trying to use an equalizer to fix room acoustics problems does not work very well. Every location in a room has a different response, so no single EQ curve can help everywhere. Even if your goal is to correct the response only where you sit, it's impossible to counter nulls. If you have a 25 dB dip at 60 Hz, adding that much boost with EQ will increase low frequency distortion in the loudspeakers. And at other places where 60 Hz is too loud, EQ makes the problem worse. EQ can reduce peaks a little, but it does not reduce the extended decay time that accompanies most peaks. Our Audyssey Report article explains why EQ is not a suitable substitute for bass traps and other treatment."


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *erkq* /forum/post/19331900
> 
> 
> I hope I can quote from a non-subscription site. The fallacy of this very well explained by Ethan:
> 
> 
> "Trying to use an equalizer to fix room acoustics problems does not work very well. Every location in a room has a different response, so no single EQ curve can help everywhere. Even if your goal is to correct the response only where you sit, it's impossible to counter nulls. If you have a 25 dB dip at 60 Hz, adding that much boost with EQ will increase low frequency distortion in the loudspeakers. And at other places where 60 Hz is too loud, EQ makes the problem worse. EQ can reduce peaks a little, but it does not reduce the extended decay time that accompanies most peaks. Our Audyssey Report article explains why EQ is not a suitable substitute for bass traps and other treatment."



Not quoting a site...but of my own volition...I hope you recognize that the description you provided is not entirely correct. Ring time is a function of the peak itself. The additional energy of the peak provides a longer ring time (check out a waterfall plot of your room if you don't believe me) due to the fact...well...it takes more time for that energy to decay to an inaudible level. By reducing the energy of a peak via a PEQ, you thereby also reduce the ring time. I certainly hope you did not come away with the idea that bass traps strung throughout the room can reduce a null by increasing that null's energy. Bass traps work the same way as a PEQ just less targeted (unless you are using a Hemholtz resonator)...they reduce the peaks...which thereby reduces the depth of the null. Believe it or not though, you can sometimes increase a null's energy via a PEQ (generally not a lot but you can) without causing audible damage or audible distortion...but I've never heard of a bass trap increasing a null's energy. I am not saying that I don't incorporate bass traps...I do through design...but I certainly do not rely on them to deal with frequency problems below 100 Hz. It's just not practical or the best method IMHO. Best wishes!


----------



## erkq




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19332144
> 
> 
> Not quoting a site...but of my own volition...I hope you recognize that the description you provided is not entirely correct. Ring time is a function of the peak itself. The additional energy of the peak provides a longer ring time (check out a waterfall plot of your room if you don't believe me) due to the fact...well...it takes more time for that energy to decay to an inaudible level. By reducing the energy of a peak via a PEQ, you thereby also reduce the ring time. I certainly hope you did not come away with the idea that bass traps strung throughout the room can reduce a null. A null is the absence of energy and thus, how can you reduce something that is already reduced? Believe it or not though, you can sometimes increase a null's energy via a PEQ (generally not a lot but you can) without causing audible damage...but I've never heard of a bass trap increasing a null's energy. I am not saying that I don't incorporate bass traps...I do through design...but I certainly do not rely on them to deal with frequency problems below 100 Hz. It's just not practical or the best method IMHO. Best wishes!



Ring time's relation to peak energy is linear. Of course.

You seem to be a knowledgeable fellow, so your characterization of a null as absence of energy and insistence that it can't be treated successfully with a bass trap is puzzling. It all depends on how you define "energy". A null is in fact the meeting of two (or more) sound waves 180 degrees out of phase with each other. One large cause of this is a sound wave reflected off the back wall meeting incoming waves from the speaker. If bass traps can get rid of, or ameliorate, this reflection, the null can be reduced considerably. In this case "reduction" of a null equates to bringing the energy back up at the null's frequency.


But I'm sure you know this... that's why it's puzzling.


PS I don't quote what I don't understand.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *erkq* /forum/post/19332216
> 
> 
> Ring time's relation to peak energy is linear. Of course.
> 
> You seem to be a knowledgeable fellow, so your characterization of a null as absence of energy and insistence that it can't be treated successfully with a bass trap is puzzling. It all depends on how you define "energy". A null is in fact the meeting of two (or more) sound waves 180 degrees out of phase with each other. One large cause of this is a sound wave reflected off the back wall meeting incoming waves from the speaker. If bass traps can get rid of, or ameliorate, this reflection, the null can be reduced considerably. In this case "reduction" of a null equates to bringing the energy back up at the null's frequency.
> 
> 
> But I'm sure you know this... that's why it's puzzling.
> 
> 
> PS I don't quote what I don't understand.



It's not really puzzling. It's just a relation of the surrounding frequencies to the null. If you drop the peaks...you eliminate the effects of the null, but what you are really eliminating is the harmful effects of the longer ring times. Yes, your analysis is correct, but in order to really effectively treat that peak....it would need to be approximately 1/4 the wavelength of that peak you are trying to reduce. In the case of 50 Hz...it would need to be 5-6 feet thick. 1/10 the wavelength is also possible provided certain specifics are adhered to...but the trap would still be 2.25 feet thick. Now, another factor to consider, bass traps as the main stream thinks of them, are made of fiberglass which is a frictional absorber. Frictional absorbers work best when something is moving against them. Along the walls...the velocity of the wave is near zero...but the pressure is much higher (boundary gain anyone) especially for low frequency waves that we are referring to. Now, since the velocity is near zero, the frictional absorber doesn't work as well as it would say at the point of lowest wave pressure and highest velocity of that wave...which is not along the walls but out in the room itself. So, I am not saying you can't use bass traps to deal with freqs below 100 Hz, but they would be impractical and obtrusive to be truely effective. Engineering and PEQ are the only way to go IMHO. BTW...you don't seem too shabby yourself in the knowledge department!







Best wishes!


----------



## KERMIE

So my Main issues are in these areas:


A. 57Hz to 79Hz

B. 116Hz to 168Hz

C. 211Hz to 221Hz

D. 230Hz to 259 Hz


For the most part the rest of the test tones were +/- 4db


----------



## Kal Rubinson




> Quote:
> Originally Posted by *erkq* /forum/post/19332216
> 
> 
> Ring time's relation to peak energy is linear. Of course.



Sure, it is linear but the actual slope depends on the Q of the peak and can be compensated for with a filter of appropriate Q.

[/quote]


----------



## erkq




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/19332719
> 
> 
> Sure, it is linear but the actual slope depends on the Q of the peak and can be compensated for with a filter of appropriate Q.



Yes. But Ethan's point is that Q (and the amplitude of the peak or null) exists in one place in the room. What about the other places? How do you use an EQ to correct the many different response curves a room has in different locations? It seems it's better to try to stop the waves from bouncing around and interacting all over the room as much as possible first and then apply EQ. I do have a Behringer FDP EQ and I use it.


So: SierraMikeBravo, I thought the bass traps were triangular or put across corners so they could interact with the higher velocity movement. And, I thought as the energy of the sound was absorbed and converted to heat, the wavelength no longer mattered for the portion absorbed because the pressure goes away with the absorption of the energy. This, of course, is only true for the portion of the energy that the trap can absorb.


So I have a question: when the energy of a sound wave is absorbed, does the distance between the absorbing material and the wall still matter other than getting the material into the high velocity area?


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *erkq* /forum/post/19332981
> 
> 
> So I have a question: when the energy of a sound wave is absorbed, does the distance between the absorbing material and the wall still matter other than getting the material into the high velocity area?



IMHO, the question should really be, what's the goal?


----------



## Dennis Erskine




> Quote:
> So: SierraMikeBravo, I thought the bass traps were triangular or put across corners so they could interact with the higher velocity movement. And, I thought as the energy of the sound was absorbed and converted to heat, the wavelength no longer mattered for the portion absorbed because the pressure goes away with the absorption of the energy. This, of course, is only true for the portion of the energy that the trap can absorb.



All of my comments below refer only to absorption of sound energy in air.


There are two commonly used mechanisms to absorb sound energy: (1) velocity type absorption; and, (2) diaphragmatic or pressure absorbers. For a velocity type absorber to function effectively, that device must be placed in a location where the velocity of the air molecules are at their maximum velocity. For a pressure type absorber to function effectively, that surface must be placed at a location where air molecule velocity is zero (or near zero) and pressure is at its maximum.


If we imagine an air molecule striking a wall, at the instant it strikes the wall, its velocity is zero and pressure is high. However, sound propagation is cyclic in nature and cycles through rarefication and compression. At maximum rarefication and maximum compression, velocity is zero and pressure at its maximum.


To achieve maximum effectiveness in a velocity absorber, that absorber should be placed such that it is located at the 1/4 wavelength of the frequency(ies) for which we wish to reduce energy. Velocity absorbers are characterized by fiberglass batts or fiberglass panels. At 80Hz, the wavelength is 14' and the quarter wavelength is therefore 3.5'. If a dimension in your room is any multiple of 14', then a velocity absorber would need to be placed 3.5' away from a wall surface to be effective at 80Hz.


A simple form of pressure absorber is a fiberglass batt with paper backing. If you imagine a trampoline, the paper backing is the surface of the trampoline and the fiberglass is the spring. Now, imagine jumping off the roof of your house onto your trampoline. The trampoline will indeed absorb some of the energy from your fall; but, the spring is going to release some of that energy back throwing you back into the air. The spring action is an issue in the design of diaphragmatic type absorbers since they can become "speakers".


One of the characteristics of modal frequencies is they, by definition, are always at their minimum velocity and at maximum pressure at the wall surface. In this situation, a pressure type absorber is more effective at the wall surface. A velocity type absorber would need to be placed at a 1/4 wave length distance from the wall surface. (At 80Hz, that's 3.5'.)


In the low frequency arena, the bigger (not only) sound quality problems are with modal frequencies (and some would argue that in a small room, it's the first three axial modes which are the real killers). [Note: in small rooms modal problems dominate from approximately 300Hz downward but generally present the biggest audible problems below 100Hz.]


The reason we typically find vendors suggesting their bass control devices be placed in room corners is because it is at the room corners where all the axial modes are at their highest pressure/lowest velocity.


The statement made by SMB is true in that general purpose bass traps/absorbers are not very effective below 100Hz. For them to work at the velocity level, they'd have to be 14' from a wall (assuming a 20Hz modal frequency). For them to be effective as pressure absorbers, they'd need to be at the wall surface (for modal frequencies). Neither is very practical. When placed any distance from a wall, their effectiveness would vary by frequency based almost entirely on their placement (a 6" difference can radically change the frequencies upon which you'd see the greatest effectiveness).


Multiple tools need be utilized to resolve low frequency sound quality issues in small rooms. These tools would include electrical as well as mechanical.


As to the question about nulls/peaks existing in multiple areas of the room, a couple of points. First, we don't give a tinker's damn about sound quality in areas of the room where no one is sitting. Secondly, when it comes to LF and modal issues, it is the amplitude of the peaks/nulls which are audible and cause us grief. As the energy to that frequency increases, the delta between the peak and null gets larger and more audible. The converse is true as well. As energy is absorbed, that delta decreases and you have more consistent response (I didn't say good, I said "more consistent"). The use of differential parametric EQ, is one means be which modal frequencies can be 'resolved' without sucking the life or energy out of a room.


Among the challenges for a well performing room is to have all frequencies not only decay at the same rate (in the seating locations), but all frequencies to have the same relative SPL. This is a significant challenge since any form of pressure, or velocity type absorber will affect different frequencies differently just based on their position in the room. Adding bass trapping devices to a small room is very helpful. It cannot, however, be a helter skelter placement nor simply putting fuzzy stuff in the corners. There will be a point at which the treatment ceases to be helpful and begins to work against your objective.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *erkq* /forum/post/19332981
> 
> 
> Yes. But Ethan's point is that Q (and the amplitude of the peak or null) exists in one place in the room. What about the other places? How do you use an EQ to correct the many different response curves a room has in different locations?



It may seem like an impossible task and there are theoretical issues. Nonetheless, there are several systems that do achieve significant improvements.



> Quote:
> It seems it's better to try to stop the waves from bouncing around and interacting all over the room as much as possible first and then apply EQ. I do have a Behringer FDP EQ and I use it.



I completely agree that physical room treatment is a better approach but most of us find that we are limited in how much of that can be accommodated. So, we do that first and finish up with EQ.



> Quote:
> So I have a question: when the energy of a sound wave is absorbed, does the distance between the absorbing material and the wall still matter other than getting the material into the high velocity area?



Yes, it will influence the frequencies that can be efficiently absorbed. (I leave the rest for the more techy experts.)


----------



## johnbomb

To those who have built/used Helmholtz resonators: can these things effectively help tame peaks (and presumably therefore the corresponding nulls) in a typical small room HT? By "effectively," I mean "a real improvement in SQ."


I ask, because I had an idea that would combine the use of these resonators and the use of corner spanning rigid fiberglass. Why not build resonators with triangular boxes (tuned to whatever problem frequencies you may encounter in the sub 300hz range) and place them in corners behind a span of say, 4" rigid fiberglass? If built and positioned correctly, such a combo could treat frequencies lower than 100hz all the way up, right?


One would have to take lots of measurements to find out which corners best support which peaks and then place the resonators accordingly. If all wall/wall, wall/floor, and wall/ceiling corners were employed, you could have a room filled with multiple resonators hidden behind fiberglass.


I plan to do this in my HT (as soon as I get to that stage- still a way to go). If no one has experience or advice, then I'll post results later... at my rate, probably _much_ later







.


Thanks,

John


----------



## Ethan Winer




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19332144
> 
> 
> By reducing the energy of a peak via a PEQ, you thereby also reduce the ring time.



That simply is not true. The relative decay time remains the same. Now, you could argue that once a ringing peak is reduced in _amplitude_ that the ringing will be less objectionable. And this is true. But the _slope_ of the decay remains the same. Versus bass traps that really do reduce the decay times. Another huge advantage of bass traps over EQ is that bass traps reduce the Q of peaks. This has a marked affect on clarity, and goes a long way toward eliminating the problem known euphemistically as "one note bass." EQ cannot alter the Q of a room's resonant peaks.


The following graphs were measured in a small room, 16 by 11.5 by 8 feet. It's the same room, and same data, as shown in my company's Hearing is Believing video.


Here are Before / After graphs showing the reduction in decay time, and the reduction in Q of the peaks, after adding bass traps to the room;




















The graphs above also prove that conventional "porous" type bass traps can indeed be highly effective to as low as 40 Hz and even lower. In this case the traps are only six inches thick, and most are not even mounted straddling corners.



> Quote:
> I've never heard of a bass trap increasing a null's energy.



That's a joke, right? The waterfalls above prove the point very well, and the response-only graph below shows Before and After overlaid to make the difference even easier to spot. I'm sure I don't have to state which line color is with bass traps and which is without.










--Ethan


----------



## Kal Rubinson




> Quote:
> I've never heard of a bass trap increasing a null's energy.





> Quote:
> That's a joke, right?



Not really. A null has low energy because of the cancellation occurring there. If you add treatment to mitigate the modal energy and smooth the response, there will be more energy at that point/frequency (as you indeed show). Otherwise, it would still be a black hole.


----------



## Ethan Winer

Now don't get all technical on me Kal!










Using common acoustic-ese, the "energy" of a null relates to the SPL at that location in the room. A lot of people wrongly believe that bass traps reduce the level of bass in a room. If a room is dominated by peaks, such as is common in a square or cube shaped room, the overpowering bass at select frequencies will indeed by reduced. But in my experience, the larger problem in _most_ rooms is nulls. So usually, after adding bass traps the perception is that of more bass. Not sure if that's also the case in your 2:2:1 room though.


--Ethan


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19336365
> 
> 
> But in my experience, the larger problem in _most_ rooms is nulls. So usually, after adding bass traps the perception is that of more bass. Not sure if that's also the case in your 2:2:1 room though.



It is and that is exactly the point I was trying to make.


----------



## Roger Dressler

Hi Dennis,


Great post--well, all you posts are darned good, but this is a keeper! One little question, though, when you said:


> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19333519
> 
> 
> The use of differential parametric EQ, is one means [by] which modal frequencies can be 'resolved' without sucking the life or energy out of a room.



What do you mean by 'differential' EQ?


Tnx!


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/19337918
> 
> 
> Hi Dennis,
> 
> 
> Great post--well, all you posts are darned good, but this is a keeper! One little question, though, when you said:
> 
> What do you mean by 'differential' EQ?
> 
> 
> Tnx!



Man, I tell ya, Dennis gets all the love!


----------



## Dennis Erskine




> Quote:
> What do you mean by 'differential' EQ?



Heck if I know ... made use of a big word though.


When you have multiple subs in the room, the first step in calibration is to have them all level matched and at the same phase. You can then calibrate in real time by adjusting phase, PEQ, and SPL of each sub (individually) to deliberately create constructive/destructive interference to further deal with modal issues. That is differential EQ. Currently (at least for me) this is pretty much trial and error along with knowing from experience what worked and what did not. Differential EQ would be an excellent PhD thesis for someone working toward a PhD in acoustics. (Hey, Todd. You busy?







)


Example with two subs. We know when you have two subs in a room, the summed behavior of those two subs is identical to having a single sub mid-way between the two physical subs (virtual subwoofer). By tweaking the SPL of the physical subwoofer you can "move" the location of the virtual sub along that line between the two physical subs. You can do that with four subs (much more a challenge and time consuming). As well if some of those multiple subs are close to the ceiling you can manage the height of the "virtual sub" as well.


----------



## pepar

Fascinating!


----------



## Elill

I've been waiting for this topic to blow up for ages. Great info SMB and Dennis.


Surely Ethan's charts make some sort of an arugment for them?


How can the change be accounted for if the science behind what Dennis is saying is correct? there must be a middle ground that involves math beyond my capability?


Say I make an ottoman and put it between the seating position and the screen (about 3-4-5ft off the front wall, that would work as velocity absorber yes? that would work? I'd planned on filling it full with 703 equivalent polyester and covering in fabric.


Not sure if:

- increasing density from outside in would help?

- plutting a plastic membrane around it and then a bit more insulation (making is a pressure absorber) would help?

- having a free air space under it i.e. Have the bottom not solid and put it on little legs? (it'll have a solid top)

- Edit: what about a ring of peboard around it?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Elill* /forum/post/19341890
> 
> 
> Say I make an ottoman and put it between the seating position and the screen (about 3-4-5ft off the front wall, that would work as velocity absorber yes? that would work? I'd planned on filling it full with 703 equivalent polyester and covering in fabric.
> 
> 
> Not sure if:
> 
> - increasing density from outside in would help?
> 
> - plutting a plastic membrane around it and then a bit more insulation (making is a pressure absorber) would help?
> 
> - having a free air space under it i.e. Have the bottom not solid and put it on little legs? (it'll have a solid top)
> 
> - Edit: what about a ring of peboard around it?



I did that with OC705 in a pillow-top, open bottom ottoman (no membranes but with ball casters) and it was fairly effective.


----------



## ExToker

I was working on our master bath remodel last weekend, prepping for tile with Cement board and that got me thinking about my theater room.


I have had a long standing problem in my theater room with 1 live wall (7.5 x 13 ft) consisting of simply studs, 3 1/2" fluffy, and 1/2" sheetrock.

Listening to the Eagles 'Hell freezes over' last night I finally cracked a joint in the wall and drew comments from the spouse upstairs, so I guess I better get on it.









So...This winters project will be to address this wall and install 9" fluffy in the ceiling joists above the tiles.



Would there be a advantage / disadvantage be using 1/2" cement board vs. 5/8" drywall on the back of the wall? Mass (psf) looks like they are pretty close to the same.


----------



## KERMIE




> Quote:
> Originally Posted by *KERMIE* /forum/post/19332553
> 
> 
> So my Main issues are in these areas:
> 
> 
> A. 57Hz to 79Hz
> 
> B. 116Hz to 168Hz
> 
> C. 211Hz to 221Hz
> 
> D. 230Hz to 259 Hz
> 
> 
> For the most part the rest of the test tones were +/- 4db




So what type of trapping would I need to do for B-D?


Thank you in advance.


----------



## Ethan Winer




> Quote:
> Originally Posted by *Elill* /forum/post/19341890
> 
> 
> there must be a middle ground that involves math beyond my capability?



Empirical evidence trumps theory every time. I'm not much of a math guy, but I know how to measure.



> Quote:
> Say I make an ottoman and put it between the seating position and the screen (about 3-4-5ft off the front wall, that would work as velocity absorber yes?



The best places for bass traps are straddling corners, and flat on the front and rear walls with an air space. Absorbers out in the middle of the room will not do nearly as much. The difference in effectiveness for the same bass trap in both places is literally three to one or even greater.


--Ethan


----------



## SierraMikeBravo




----------



## eiger

Hi Guys,


I need some advice on where to place some panels.


I have 8 panels in my room currently. 3 up each side wall and two on the front wall. I have two extras that are basically doing nothing in my closet and I'm considering them on the ceiling.Would you guys reccomend hanging them so they run width across, or so they run front to back?


I've seen people do both.


Does it really matter that much? ;-)


----------



## Ethan Winer

The two main places for absorbing panels is in corners for bass trapping, and at specific first reflection points. More here:

Acoustic Basics 


--Ethan


----------



## eiger

That's very informative and helpful Ethan, thank you.


Specifically though, does exact orientation of say a 2 x 4 panel matter for ceiling mounting or would results from both be fairly negligable?


----------



## Ethan Winer

The "best" bass trap placement depends on what frequencies end up in what parts of the room. My approach is to have traps cover as much total corner surface as possible, including wall-ceiling and wall-floor corners when possible. Another method that's a bit more intelligent is to use bassy pink noise to find where bass builds up the most:

Pink noise aids placing bass traps 


Wherever the bass is strongest is the best place for traps.


Reflection points are very specific places, so there's not much leeway there.


--Ethan


----------



## ramzy

The wife and I are currently shopping for a contractor to build a 12x10 dedicated theater room. One concern for me is outside noise. I'd like the room dead quiet from outside noise, but considering our budget, I know that will not happen. I have read about adding another layer of sheetrock to help with sound. Any other inexpensive techniques worth mentioning or specific materials to use?


----------



## Elill




> Quote:
> Originally Posted by *ramzy* /forum/post/19354231
> 
> 
> The wife and I are currently shopping for a contractor to build a 12x10 dedicated theater room. Once concern for me is outside noise. I'd like the room dead quiet from outside noise, but considering our budget, I know that will not happen. I have read about adding another layer of sheetrock to help with sound. Any other inexpensive techniques worth mentioning or specific materials to use?



Soundproofing and acoustic treatment are two different matters (except for one relating point which i wont go into)


Have a read of www.soundproofingcompany.com under their articles sections.


The first thing you need to do is isolate the room. Either using double studd walls, staggered studds or isolation clips


Then if you add mass and dampening you'll be there. The door is critical, as it any other "hole" including HVAC, electrical fittings (lights, points, switches etc)


But isolation is key - along with removing all holes - think fish tank full of water, any little opening sound will find its way out.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Elill* /forum/post/19354612
> 
> 
> Soundproofing and acoustic treatment are two different matters (except for one relating point which i wont go into)
> 
> 
> Have a read of www.soundproofingcompany.com under their articles sections.
> 
> 
> The first thing you need to do is isolate the room. Either using double studd walls, staggered studds or isolation clips
> 
> 
> Then if you add mass and dampening you'll be there. The door is critical, as it any other "hole" including HVAC, electrical fittings (lights, points, switches etc)
> 
> 
> But isolation is key - along with removing all holes - think fish tank full of water, any little opening sound will find its way out.



Well, I wish it were that easy. Believe me, I know first hand.







Every room is different, and I have had the whip cracked over my head from you know who many times to prove it.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *ramzy* /forum/post/19354231
> 
> 
> The wife and I are currently shopping for a contractor to build a 12x10 dedicated theater room. Once concern for me is outside noise. I'd like the room dead quiet from outside noise, but considering our budget, I know that will not happen. I have read about adding another layer of sheetrock to help with sound. Any other inexpensive techniques worth mentioning or specific materials to use?



You are certainly headed in the right direction. The wrong direction is trying to keep all the sound in.


----------



## erkq




> Quote:
> Originally Posted by *ramzy* /forum/post/19354231
> 
> 
> The wife and I are currently shopping for a contractor to build a 12x10 dedicated theater room. Once concern for me is outside noise. I'd like the room dead quiet from outside noise, but considering our budget, I know that will not happen. I have read about adding another layer of sheetrock to help with sound. Any other inexpensive techniques worth mentioning or specific materials to use?



Another layer of drywall won't do much. But put a layer of Green Glue between them and it'll do a lot. You have to be careful to box in receptacles, switches, etc. or the sound will go through those too.


----------



## Elill




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19354643
> 
> 
> Well, I wish it were that easy. Believe me, I know first hand.
> 
> 
> 
> 
> 
> 
> 
> Every room is different, and I have had the whip cracked over my head from you know who many times to prove it.



.....yeha yeah I know. But my response was as broad as the question....


Edit: he's gotta start somewhere


OP - if you want this done right, I mean really right. Engage SMB or Dennis Erskine to advise


----------



## ramzy

Thanks for the advice everyone. I'm weighing my options at the moment which frankly are a bit limited, but I at least wanted to try and put some effort into noise control. I won't be able to spend much, but its certainly better than nothing.


I understand room treatments and soundproofing are 2 different things. Fortunately, the wife is on board with room treatments thanks to the opportunity she sees in it as room decor.


If you could only do 1 or 2 inexpensive things on either the walls, ceiling, or floor to dampen outside noise what would you do?


----------



## erkq




> Quote:
> Originally Posted by *ramzy* /forum/post/19355687
> 
> 
> If you could only do 1 or 2 inexpensive things on either the walls, ceiling, or floor to dampen outside noise what would you do?



How is the room situated relative to the rest of the house? Are there rooms above? below? only to the side? For example my theater has nothing above or below and one exterior wall, so I'd treat the 3 interior walls only.


----------



## ramzy




> Quote:
> Originally Posted by *erkq* /forum/post/19355737
> 
> 
> How is the room situated relative to the rest of the house? Are there rooms above? below? only to the side? For example my theater has nothing above or below and one exterior wall, so I'd treat the 3 interior walls only.



Its in the corner of the house, in the basement with 2 exterior walls facing south and east. It has rooms facing it along 2 walls, north and west, and a room above it.


----------



## CJO




> Quote:
> Originally Posted by *ramzy* /forum/post/19355779
> 
> 
> Its in the corner of the house, in the basement with 2 exterior walls facing south and east. It has rooms facing it along 2 walls, north and west, and a room above it.



Are the exterior walls for the room above ground or below ground?


CJ


----------



## ramzy




> Quote:
> Originally Posted by *CJO* /forum/post/19357351
> 
> 
> Are the exterior walls for the room above ground or below ground?
> 
> 
> CJ



The house is a split level, if you can picture those basements....half of it is below ground, the other half is above ground.


----------



## troylavigne

Just a quick post to let people know that if they are looking for oc703 (owen's corning 703) in Atlantic Canada, here's where I am buying mine. Took me several hours to

find the place, mostly thanks to a very helpful guy at Kent's building supplies who

placed a bunch of phone calls for me. They stock oc703 2" unfaced, I think it was

around 88 cents per sqft. I'll be building my acoustic panels in a few weeks.


General Insulation

120 Troop Avenue

Dartmouth, NS B3B 1Z1

(902) 468-5232


----------



## Jeff Smith

Quick question...does this work? Seems different from all other bass traps.

http://www.diy-home-theater-design.c...rap-build.html


----------



## Ethan Winer

^^^ No, that doesn't work. Not even a little. That page is the laughing stock of people knowledgeable about acoustics.


--Ethan


----------



## Andrew Steele

Hi Ramzy


I see you say outside noise, is this noise from outside the house or _all_ noise outside the room?


Go down to your basement for a while and sit in the general location you are planning on having your theater, listen to what noises you hear, how loud are they? Have you wife walk around normally in the room above, have her move a chair if the room above has any. Have someone flush the toilet, operate faucets etc, do these create significant noise in your proposed theater area?


This is the best way to identify what the main sources of noise are without paying an engineer to come out and assess the situation for you, it could be that you're more sensitive to the neighbors dog barking, than say, footfall from the room above.


If you want to get the most bang for your buck (or least bang, in your case) you'll be better off using your ears to start with, determining the problem sources and going from there.


Also, take some pics - post em. The more details we have, the better.


Cheers


Andrew


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19403539
> 
> 
> ^^^ No, that doesn't work. Not even a little. That page is the laughing stock of people knowledgeable about acoustics.
> 
> 
> --Ethan



Well, at least he isn't recommending that one fill it with sand!


----------



## Ethan Winer




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/19405712
> 
> 
> Well, at least he isn't recommending that one fill it with sand!



That "bass trap" is indeed just an empty cardboard tube filled with sand.










--Ethan


----------



## pepar

They should use BS as they seem to have a large supply of it.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/19405712
> 
> 
> Well, at least he isn't recommending that one fill it with sand!





> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19408728
> 
> 
> That "bass trap" is indeed just an empty cardboard tube filled with sand.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --Ethan



Whooops. I recalled that he did but when I scanned it yesterday, I somehow missed that dirty word. Mebbe he should publish a _tweak_ where he replaces the sand with mineral wool.


----------



## FuzzyZipperbaum

I have some areas where normal size base traps would be too big. However, I could make some bass traps that would be more in the 12 x 12 size for a few spots like under a 3rd row bar....would this be of any help or are they too small to do much


----------



## nathan_h

12 inches by 12 inches by what?


----------



## Ethan Winer

12x12 bass traps might help a little if they're at least 4 inches thick, but it's not a real solution unless you have like 20 of them.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/19427881
> 
> 
> 12 inches by 12 inches by what?



By a 3rd row bar!


----------



## Jeff Smith

I need advice. I moved and am setting up an new HT.


Room is 17'3" front to back, 19'2" wide, 9'10" tall. Drywall, perfect rectangle. Only openings are 6' wide glass doors on each side wall, centered on the L and 1' forward of center on R. I plan on treating these with 4" of 703 for 1st reflections and bass trapping. Also treating the ceiling 1st reflection with 2" of 703. Best seats have heads 6' from rear wall, 11' from front.


Equipment: Lexicon DC2, Atlantic Tech 450 LCR, side and rear surrounds. 2 M+K 350 THX subs that I will place where advised, but an favoring the midpoints on the front and rear walls with time delay correction.


The screen is 10' wide and flanked by velvet curtains so none of the front wall will show at all and I can do any treatments so they will be invisible.


Years ago I built 3 DIY "tube traps" 18" diam. 8' tall. fiberglass insulation sandwiched tightly between wire cylinders, hollow center. I dont know if these are still considered good or if the 4" thick flat panels of 703 are better. I would still use them somewhere, as it seems the advice here is "more is better."


Corners - is the superchunk method worth it or are flat panels with air gaps (or with loose fill behind) better. I read all I could, and Ethan says at one point that the air gap is better because there's no energy to absorb at the wall, but in another place he seems to say better performance could be gained by filling the area behind a corner base trap. I think these statements may have been years apart.


Superchunks - if the best DIY bang for the buck, is it better to have the 24" wide go floor to ceiling or the 34" wide just do the 8 corners, with a gap in the middle. This is a cost question, as both cost the same but the 34" size would put more mass in the 8 corners.


Wild idea - carpet the entire front wall. I found an infinite supply of used carpet, and could put it 2-3 layers thick on the entire front wall, either on the wall, or hanging 3-4" off with an air gap. I could also use rolled pieces up to 12" rolls all along the floor at the front walls. None of this would be seen, so color or style wouldn't matter, and I could add later as needed. I thought about how much sound the carpet absorbed when walking in the store between the aisles. Would this work? Its free, and I could never afford 703 in those areas.


Finally, need advise on where to place the side and rear surrounds. Is it a obvious as 2 on the side walls as far back as head level and 2 on the rear walls? Any advice there?


----------



## Ethan Winer

Filling a corner solid is better than a flat panel straddling the corner, but only a little better. If the cost of materials is not a concern, go ahead and fill the corner. Otherwise don't bother, and instead use the same amount of material to have more bass traps straddling additional corners.


--Ethan


----------



## Jeff Smith

So, is it better to do the entire corner (where walls meet - about 10' tall) floor to ceiling with the flat trap, or just the 8 corners (where floor or ceiling and 2 walls meet) with triangles? From reading your (and other) site, I would guess do the corners heavier.


For the same money, I could do the top and bottom 2' with 34" wide 703 or the top and bottom 4' with 24" wide 703 in triangle chunks. Which would be better bang for the buck?


If needed, another $70-80 would get me 34" wide triangles covering the top and bottom 30"...again, where's the happy medium?


I would do all 8 corners the same. I can afford the 34" in all 8 corners, but is 24" tall enough or does it need to be taller? For another $70-80 I could make all 8 corners 34" wide and 36" tall.


I'll try to get your opinion on this part first before asking about other ideas...I realize I asked a lot at once.


----------



## FuzzyZipperbaum




> Quote:
> Originally Posted by *nathan_h* /forum/post/19427881
> 
> 
> 12 inches by 12 inches by what?




So are you saying I didn't give enough info??? LOL...


Room is irregular as you can see. 50' long by 18' in most areas and 22' in the widest. I am doing BTs in the front corners...1" on the false wall and along the sides from floor to soffits as drawn... I am going to add a 12x12 bt in the corner of the bar area.... 4" on the back wall...


My problems is the floor is tiled, and along one side I have a large sliding glass window and then at the end of the room 3 large bay windows that will have stones around them...light is not a problem....


So I need all the help I can get. I am also going to punch a bunch of holes in the riser that is build in chambers the largest is half of the riser and then the next 3 each half of each other...I know this can be tricky.... I may also if I need the extra help knock some 8"x8" holes all around the soffits that are filled all the way up with insulation and then put some type of decorative cloth over them...


My question was for under the 3rd row bar which is about 11'L... because I will have some pictures on the back wall I wanted something under there to catch any rebounds so to speak.....


Thoughts?


----------



## FuzzyZipperbaum

oh...and the darker lines on the sides of the theater are where the 1" is and I am also going to go with 2" under bar.


----------



## nathan_h

I would say make the stuff on front and side walls thicker, but -- especially on the side walls -- don't cover "everything". Use the mirror trick on the side walls. You'll still end up with a lot of coverage but less than you are planning. Making the panels thicker will do a better job of consistently treating the sound over a broader range of frequencies, instead of just killing the high end and air. And covering less wall will leave some liveliness in the room.


On the back, if you can leave that open to the other area (which I think is your plan) I would not worry too much about panels. That much space is even better than panels, IMO.


----------



## Jeff Smith

Anyone ever think of hanging mult layers of old carpet on the front wall? I have found an infinite supply of free used carpet, and my front wall is completely hidden by screen and velvet curtains, so nothing shows. I would put 3-4 layers thick, nail gun the top to a 2x4 from the side wall to the screen, and hang the 2x4 from the wall or ceiling joists. Simple and easy to adjust the air gap behind from 0-X inches. I could cover floor to ceiling...go stand in a carpet store and listen as you move near rolls stacked up, impressive quietness. This could be a free DIY addition.


The other thing that's cheap for a front wall I thought of (using Bob Golds absorbtion coefficients) was unfaced R38, 12" thick fiberglass batts on the whole wall. Covered with a cheap sheet to keep fibers from flying free, still behing the velvet curtains. The absorbtion coefficients for this is far more than any of the fiberboards (Rockboard 60, 703, etc, even at 4") and its cheaper by far also (although not free like the carpet).


----------



## Ethan Winer




> Quote:
> Originally Posted by *Jeff Smith* /forum/post/19436308
> 
> 
> So, is it better to do the entire corner (where walls meet - about 10' tall) floor to ceiling with the flat trap, or just the 8 corners (where floor or ceiling and 2 walls meet) with triangles?



What matters is the total amount of corner surface that is covered. Also, a rectangle room has 12 corners, not just 4. The more total corner surface you cover the better. When you treat an entire corner, such as where two walls meet from floor to ceiling, you are also including the tri-corners. So that's the way to think about this.


--Ethan


----------



## Jeff Smith

So I'm still not clear. I know it has 12 corners, and 8 trangle corners (never thought 4m of either).


Given a budget which can purchase a fixed amount of 703 or rockboard, better to concentrate heavier on the tricorners, or lighter and extend down thw walls from the tricorners. ceiling/wallfloor corners are out-WAF, and the front floor is hidden, that's ok.


How about carpet?


----------



## Ethan Winer

This is impossible to answer without 1) knowing the total amount of corner surface, 2) the total amount of 703 you can afford, and 3) being there to try different 703 placements while measuring the results. Again, if you can cover the entire length of all junctions with 703 at least four inches thick, that's what you should aim for. If you can't afford that much 703 now, do only some corners completely and plan to do more in the future.


--Ethan


----------



## JapanDave




> Quote:
> Originally Posted by *Jeff Smith* /forum/post/19448264
> 
> 
> I just reread Bob Golds absorbsion coefficients. It looks like a single 12" deep batt of "fluffy pink" OC R38, mounted on wall with no gap, absorbs better at allmost all frequencies than 703. Why not just use this? Cheaper, and I could cover all the front 4 corners and the soffet over the screen, and, in reality, the entire front wall that isnt taken up by the screen for much less than 703. None of this would show, and I would still run 4" 2' wide, floor to ceiling rear corners like you suggest-as they would show.
> 
> 
> Other than more pleasing esthetics, why not go this route. Its far cheaper, and (if you believe his numbers) a better absorber. I know it's less dense but the thickness seems to make up for it. Again, this would all be hidden.



A 6" thick OC 703 on wall absorbs more than the 12" of "fluffy pink" on wall.


EDIT: How did my post get ahead of yours??? I must have read your mind!


----------



## Jeff Smith

I just reread Bob Golds absorbsion coefficients. It looks like a single 12" deep batt of "fluffy pink" OC R38, mounted on wall with no gap, absorbs better at allmost all frequencies than 703. Why not just use this? Cheaper, and I could cover all the front 4 corners and the soffet over the screen, and, in reality, the entire front wall that isnt taken up by the screen for much less than 703. None of this would show, and I would still run 4" 2' wide, floor to ceiling rear corners like you suggest-as they would show.


Other than more pleasing esthetics, why not go this route. Its far cheaper, and (if you believe his numbers) a better absorber. I know it's less dense but the thickness seems to make up for it. Again, this would all be hidden.


----------



## Dennis Erskine




> Quote:
> How did my post get ahead of yours??? I must have read your mind!



It's that international date line thingy between the two of you.










His today is your tomorrow, so you saw the post before he posted it .. that time warp will get you everytime. I have that same issue with my clients in OZ. They send me comments on my design ideas before I do them. Great time saver.


----------



## nathan_h




> Quote:
> Originally Posted by *Jeff Smith* /forum/post/0
> 
> 
> I just reread Bob Golds absorbsion coefficients. It looks like a single 12" deep batt of "fluffy pink" OC R38, mounted on wall with no gap, absorbs better at allmost all frequencies than 703. Why not just use this? Cheaper, and I could cover all the front 4 corners and the soffet over the screen, and, in reality, the entire front wall that isnt taken up by the screen for much less than 703. None of this would show, and I would still run 4" 2' wide, floor to ceiling rear corners like you suggest-as they would show.
> 
> 
> Other than more pleasing esthetics, why not go this route. Its far cheaper, and (if you believe his numbers) a better absorber. I know it's less dense but the thickness seems to make up for it. Again, this would all be hidden.



You are right , it's the rigidity and relatively less bulky nature of the 703 which make it the more popular choice, not the superiority of 703's acoustic properties. If you have space and a way to contain it without solid covering for a foot thick / deep of fluffy pink that's not a bad choice.


----------



## JapanDave




> Quote:
> Originally Posted by *dennis erskine* /forum/post/19448659
> 
> 
> it's that international date line thingy between the two of you. :d
> 
> 
> his today is your tomorrow, so you saw the post before he posted it .. That time warp will get you everytime. I have that same issue with my clients in oz. They send me comments on my design ideas before i do them. Great time saver.



lol :d


----------



## adude

Just like you leave from Tokyo on evening and land in LA at 1100 AM same day, earlier than you started.


----------



## FuzzyZipperbaum




> Quote:
> Originally Posted by *nathan_h* /forum/post/19437341
> 
> 
> I would say make the stuff on front and side walls thicker, but -- especially on the side walls -- don't cover "everything". Use the mirror trick on the side walls. You'll still end up with a lot of coverage but less than you are planning. Making the panels thicker will do a better job of consistently treating the sound over a broader range of frequencies, instead of just killing the high end and air. And covering less wall will leave some liveliness in the room.
> 
> 
> On the back, if you can leave that open to the other area (which I think is your plan) I would not worry too much about panels. That much space is even better than panels, IMO.



I'l LOVE to not have to order that much 703 but I worry with the tile and the soffit adding more corners...add in all the glass, stone work around the windows and irregular shape...I'm worried what you are suggesting isn't enough! Also I didn't put in the plans but I have 2 columns that stick out about 6" on the sides and they would about half way in the path of the "mirror" trick....


any thoughts out there to this?


----------



## erkq




> Quote:
> Originally Posted by *FuzzyZipperbaum* /forum/post/19453624
> 
> 
> I'l LOVE to not have to order that much 703 but I worry with the tile and the soffit adding more corners...add in all the glass, stone work around the windows and irregular shape...I'm worried what you are suggesting isn't enough! Also I didn't put in the plans but I have 2 columns that stick out about 6" on the sides and they would about half way in the path of the "mirror" trick....
> 
> 
> any thoughts out there to this?



Those columns blocking the "mirror" trick would similarly block the sound reflection. The "mirror" trick will show you how much.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *erkq* /forum/post/19454178
> 
> 
> Those columns blocking the "mirror" trick would similarly block the sound reflection. The "mirror" trick will show you how much.



If you consider the column just a part of the wall and not an obstacle, it will work just fine. There have been several designs where the column is right in the "middle" of the primary side wall reflections, and that's ok as long as it's keep in mind that the column will have to be treated as well. This can be done easily without making it look like it was treated. It all depends on how the columns are designed. Best wishes!


----------



## FuzzyZipperbaum

The plan has always been to cover the columns for that reason...I guess the question I am wrestling with is do I go with 703 2"thick 54" up and leave an untreated wall to the soffit or just stick to my original plan and do 1" all the way up.


----------



## Dennis Erskine




> Quote:
> Just like you leave from Tokyo on evening and land in LA at 1100 AM same day, earlier than you started.



I had the opportunity years ago to fly the Concorde from London to Washington, D.C. I really like that arriving before I left thing.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *FuzzyZipperbaum* /forum/post/19456384
> 
> 
> The plan has always been to cover the columns for that reason...I guess the question I am wrestling with is do I go with 703 2"thick 54" up and leave an untreated wall to the soffit or just stick to my original plan and do 1" all the way up.



Hi Fuzzy,


You can actually design it so that the fuzzy stuff is flush with the column edges inside the column face. If you do that, you could do whatever you wish, but I would likely go most of the way up. Thickness is dependent on what you are trying to target, but I generally use 2". My suggestion though on using strictly broadband absorption is that it will likely not produce the sound you may be after. I would suggest something along the abfusor idea. Best wishes!


----------



## llj

Below find a cross section of the equipment rack for my planned theater.


The rack is built into the wall of the theater. The backend of the rack lives in an adjacent alcove. The backend of the equipment rack will be enclosed by a cabinet.











I'm trying to accomplish two objectives simultaneously. Cool the equipment in the rack and get some air changes in the theater.


On the very left you can see the back/side of a maple facia for the equipment rack. Then the rails to which standard trays will be bolted. The rack cavity where the equipment will live. Towards the top there is a serpentine air path winding its way through 3 layers of 1 inch 703 like fiberglass. Although not shown, the walls of the cabinet will also be lined with 703.


At the top is a Panasonic bathroom fan/air mover. The air mover vents out the top of the cabinet in the alcove.


The thin black line attempts to show the basic airflow.


The theater is ~2700 ft^3. The larger Panasonic fans claim 130 cfm even with significant backpressure. 2700/130 = 20 minutes/air change, or three per hour. Given this type of airflow, I'm not worried about equipment overheating.


The alcove into which I'm going to dump warm, humid theater noise laden air is rarely occupied. Its more of a service area than a living area. It is also quiet. I'm not so worried about impacting this area, or about noise from this area impacting the theater.


Fan noise raising the noise floor of the theater may be an issue. The Panasonic fans are alleged to be quiet, but this is as applied to a bathroom, not a home theater. I'm expecting (hoping) the circuitous, fiberglass lined air path will aborb most of the fan noise.


Any comments about my contraption?


Will I achieve my objectives?


Any ideas how to make it better?


Thanks.


llj


----------



## ExToker

I can offer some info on the fan as we have the 240cfm in our bathroom. It is recommended to install the fan 8' downstream (using insulated duct), so I would imagine that is where they get the db rating from. I would try to find out the actual dbs at the mouth of the fan. Or maybe you can mount the fan further away from the cabinet? I would also anticipate a little rattling at a later date, just in case........


----------



## TMcG

I see a number of issues with your plan and here are some of the reasons why I would not recommend this route:

- Why put the "muffler" inside the equipment rack instead of building it on top to conserve precious rack space?

- The idea of lining the inside of the cabinet with 703 as compared with the outside is also not ideal since you will constantly have small glass fibers & dust raining on your equipment. I would use two layers of substrate - even green glue on the outside of the cabinet to reduce the impact of noise to your other area

- The Panasonic fans are very quiet, but I would be hesitant to use this as a source of ventilation for your theater in addition to your rack. Without a lengthy HVAC conversation on pressure balancing, it is generally a bad idea to try to vent to another closed zone - the air has to go somewhere and be relatively "free"

- Another reason to not oversize the cooling fan is you will be sucking a HUGE amount of dust in through the front of your rack. Give it even just a day to build up and you would probably regret such a ventilation system, not to mention the potential for "whistling" through the rack if you used custom rack shelves

- How do you plan to wire / access the wires to this system? I could not discern from your diagram and descriptions. You may only need to connect something every once in a while, but with only front access it would be a major PITA

- And how is this fan controlled? By a simple wall switch? There is always high potential for those not experienced with your system to not know to turn the fan on and off. Even if your system is "off" your equipment will still generate heat that you may wish to evacuate through automated control / thermostat.


My recommendation would be to get an appropriately sized (rack height) Middle Atlantic AXS rack with a quiet fan panel which is thermostatically controlled. First, build a completely sealed box in your alcove with two layers of 1/2" ply with green glue in-between that will fit the rough dimensions of your AXS rack. Run a dedicated power outlet using a surface mount box on the upper part of the rack. Then, get yourself a Middle Atlantic AXS rack to fit your new sealed alcove. Use a 3-space quiet fan panel with thermostatic control at the top three spaces of the rack.


As for the warm theater - just deal with that separately through additional HVAC supply or have a professional balance your system with dampers for increased supply in your theater area. Your rack will be a few degrees within the theater's ambient temperature and then you can adjust your house system to make your theater more comfortable.


I hope this helps and good luck!


----------



## llj

I just received a Panasonic FV-08VK1. This is a DC motor powered, 80 CFM, 4" duct unit.


I have another application (non theater) for this, but part of the reason I bought it was to do a little hands on experimentation.


Sitting on the bench, it is indeed quiet. I think my contraption would probably render the bench measured noise level inaudible inside the theater.


However... if you restrict the inlet, or the outlet, thereby increasing backpressure, fan speed and noise increase. Not dramatically, but noticeably.


The key to achieving low fan noise is achieving unrestricted airflow. The outlet vent pipe has a single elbow and short run. There's not much I can do about it. On the inlet side I can manipulate the rack design, giving priority to airflow.


There's one more mystery... the speed controller in the Panasonic fan. Pressure sensors wouldn't work. They must be generating some sort tach speed versus current load line and then intersecting some airflow line. Don't know enough about DC motors to know for sure. Its a good trick. Probably something on the Internet if I wanted to look for it.


llj


----------



## llj

Thanks for such a thoughtful reply.


As far as HVAC goes... the theater is unusual because it has no HVAC vents. This

might seem strange, but its not. The concrete floor has radiant heat. The room

is more or less in a basement and nominally doesn't need air conditioning.


So, there is no HVAC system to balance.


I recognized from the beginning that a dozen bodies in a closed room, plus equipment, etc is probably going to get stuffy. I've installed the wiring and tubing for a mini-split air conditioner. But this is my backup plan. I really don't want an air conditioner and am attempting to get the air changes high enough to avoid it. Perhaps the air conditioning would only be necessary for a packed house.


There is a spot for a fresh air inlet to the theater. This is also required for the planned projector doghouse. I'm planning a similar setup to suck theater air through the doghouse and eject it outside the theater. I pick up some more air changes with this, but they won't be across the occupied section of the theater so they're not so effective.


As far as the double wall green glue etc.... well, I'm rack width constrained. Although maybe I could sandwich a couple layers of 1'4" MDF and green glue? The drawback of this is I lose the absorbtion on the inside of the rack.


As for the fiberglass particles... isn't this stuff supposed to used inside HVAC ducts? or is that Linacoustic? Would Linacoustic work?


As for the dust... In my living room, I've got a somewhat similar system. Much more ad hoc and after the fact than this. Its been there for seven years without problems. In fact I expected more dust than I've seen. I don't think its ever been cleaned.


Controlling fan operation is an issue because the room may be used for purposes other than theater. In which case a thermostat in the rack won't work. One way to cover most usage models is to implement an "OR" function of occupancy and theater active. Developing the theater active signal is easy. The occupancy signal is more difficult. May have to compromise with "lights on".


LV wiring and power comes down inside the wall and into the rack. Some details to work out here. Worst case is I'll have to give up a rack slot for the wires.


The rear of the rack box is accessible when the cabinet door on the alcove side is opened. The rear of the rack box will be removeable or maybe hinged. I probably don't have room for a slideout rack.


llj


----------



## nathan_h

The air won't change if you are only sucking air out of the room.


----------



## TMcG

I agree. And that was my point. His ambient temperature is the best he can expect. People / equipment will certainly elevate the temperature in the space over time. The solution with the rack ventilation was essentially to have the equipment just over ambient temperature, assuming that the basement would never reach crazy hot temperatures - although uncomfortable. Cheers.


----------



## llj

I don't understand why "the air won't change if I'm only sucking".


Assuming I've got an appropriate inlet air channel??


I understand that the theater room air will be no cooler than the inlet air. Under some conditions, say only a few people in the room, I'm pretty sure the elevation will be tolerable. At some point this breaks down. I'm not an HVAC guy so I don't know when But that's where the AC comes in if necessary.


You need to understand that I don't have HVAC and that its impractical to install one beyond the mini split.


llj


----------



## pepar




> Quote:
> Originally Posted by *llj* /forum/post/19498207
> 
> 
> I don't understand why "the air won't change if I'm only sucking".
> 
> 
> Assuming I've got an appropriate inlet air channel??



Well then, you're not just sucking. You're getting blown, too.










There is a "supply" even if it is passive. "Supply" and "return" are both necessary. One without the other and there is no air flow.


----------



## razz589

I am in the process of converting a finished basement into a theater and will be using inwall speakes and AT screen.


Since I have existing wood trim that I don't want the acoustic panels to stick out too far past, would it be of any benefit to only use 1/2" linacoustic on the screen wall instead of 1"?


----------



## pepar

Quote:

Originally Posted by *razz589* 
I am in the process of converting a finished basement into a theater and will be using inwall speakes and AT screen.


Since I have existing wood trim that I don't want the acoustic panels to stick out too far past, would it be of any benefit to only use 1/2" linacoustic on the screen wall instead of 1"?
Not much. Many use 2".


Jeff


----------



## TMcG

Pepar is right, and this is the lengthy HVAC discussion I was avoiding in my very first post to your question. You must have supply and return. If you have a passive supply, such as a window, door, hole in the wall, etc. then your air flow will be directly from your passive source to your active source - in this case the proposed Panasonic fan through your rack. But this won't accomplish what you are ultimately looking for - pulling heat out of a multi-bodied theater.


For example, let's say your rack alcove is near your theater door entrance. The pressure balancing I was talking about will create a flow of air between the door straight down to your alcove and NOT ventilate your room like you would like. Granted, there will be some thermal exchange between warm and cool air, but ultimately it will have little to no impact. And even if your passive supply (i.e. a "hole in the wall") is allowing air into a tightly sealed room with the only escape being the ducting attached to your equipment rack, this will NOT allow for thorough mixing of the air in the room to cool it down to the same ambient temperature as the rest of your house (the area just outside your theater). There will be some minor air mixing, but nothing of any consequence whatsoever.


So, to address your original question / concern . . . exhausting the heat from your equipment into the theater through a single whisper quiet fan panel with multiple variable speed fans is not going to have that great of an effect on the overall temperature in your theater room. Any heat impact will be minor in such a large theater space. So as long as your equipment is ventilated, putting the "heated" air from your equipment inside or outside the theater is not going to really matter. So I would close up your equipment alcove and use the thermostatically controlled fan panels.


Now, for the greater problem of cooling / ventilating your room. A picture of your room would help greatly, but even if you used one Panasonic fan to supply your room and then used another of the EXACT same Panasonic fan to remove heat from your room would be your least expensive pure forced ventilation option. The supply fan would be installed in a separate room of your house and then ducted into your theater. In other words, the "exhaust" of this fan would be coming into the theater room, preferably near your seating position. The other fan would be located on the ceiling or as high on the wall as you can at the OPPOSITE side of your supply fan to allow for proper mixing of the room's air. Keeping the fan high will obviously capture the warm air that has risen to the top of the room.


Your only other option is to add the dreaded air conditioning unit. Let me know if you have any other questions.


----------



## nathan_h

In fact, one might argue that the shallow depth might do more harm than good (shallow depth = only working on a small range of frequencies at the high end of the audible range which can suck the air out of the high end of the sound because it only deadens sound at those high frequencies instead of a broader wider more even impact across more of the audible range -- which is what a thicker panels does). A few thicker panels with nice wood trim around them that is compatible with the look of your room might serve the sound better.


----------



## ox1216

Whould putting a light behind an acoustic panne and having off the wall 4" instead of flush affect its affectiveness?


-Alan


----------



## nathan_h




> Quote:
> Originally Posted by *ox1216* /forum/post/0
> 
> 
> Whould putting a light behind an acoustic panne and having off the wall 4" instead of flush affect its affectiveness?
> 
> 
> -Alan



The air gap typically helps improve effectiveness.


----------



## kevinzoe




> Quote:
> Originally Posted by *ox1216* /forum/post/19508292
> 
> 
> Whould putting a light behind an acoustic panne and having off the wall 4" instead of flush affect its affectiveness?
> 
> 
> -Alan



Hi Alan,

The answer is "it depends" on what kind of panel it is.


If it's a resistive-type filled with fiberous material (i.e. fiberglass) then an air space behind the panel is your friend and will allow the panel to absorb to deeper frequencies; placing the absorption out from the wall equal to 25% of a wavelength maximizes the absorption abilities of a resistive-type panel. A 4" air gap is equivalent to 25% of 847Hz. Try and pull it out further to say 6.8" or more to get absorption down to 500Hz which is at the top end of most domestic room's transition frequency zones. Absorbing a broad range of frequencies is best so as not to throw off the spectral balance of the reflections and reflections of those reflections.


If the panel is a diaphragmatic-type which is best hung right against the wall for max effectiveness then moving it out 4" will diminish its effectiveness.


Hope this helps somewhat.


----------



## electrostat

Hi - plse let me know if this should be a new thread, but it seemed to go here.


I'm building a mancave from scratch... the current design is shown below. This is a golden trapagon, with ideal average dimensions. Speakers as shown are placed per Vandersteen method.


I'm thinking that I should start with 'superchunk' type traps in the 4 corners, and first reflection broadband (4", w/ about 1 1/2" air space behind) built into the walls as shown on the front and side walls and the ceiling. Does this seem reasonable? I'd like to incorporate all I can into the construction. I'll probably need diffusion on the rear wall as well?? I don't want a dead room.


Appreciate any advice. Thanks!

Attachment 192102


----------



## eiger

Guys,


Need some guidance on treatments.


I have a dedicated room 26 x 16 x 8 in a basement. Split level home. I have dual 18" sealed subs and needless to say, I hit high SPLs etc.


I have panels against all my main reflection points in the room and am working bass traps.


However my main issue right now is that I want to contain sound within the room so that it's not as loud in the upstairs part of the living room. What are my options here to seal the room off in terms of sound from the rest of the house.


Re-drywalling is not an option. I believe it's single drywall, older house.


----------



## Dennis Erskine

It's rather late in the game to be looking at sound isolation. And, since you have no interest in adding a layer of drywall, you're pretty much SOL. I would image you have holes in the drywall for HVAC vents and recessed lights as well.


----------



## Dennis Erskine

Electrostat ... looks like you have some great bass traps already ... they are called "windows". With a two channel room, your early reflection points should be diffusors or absorbers.


----------



## eiger




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19544963
> 
> 
> It's rather late in the game to be looking at sound isolation. And, since you have no interest in adding a layer of drywall, you're pretty much SOL. I would image you have holes in the drywall for HVAC vents and recessed lights as well.



Thanks Dennis.


I know it's a tad late. Because it's not new construction, I was limited with existing structure when we moved in. I was afraid you were going to say that. I guess I need to look into how much work it would be. Yes, note the huge vents in HVAC in pics.


I already freshly painted and textured not long ago, so the thought of adding a layer of drywall to ceiling doesn't thrill me much.


Here is the room as it stands now.


















GRRR. Shoulda, Coulda, Woulda


----------



## electrostat

Dennis, yes...although they can't be open all the time!

Any other thoughts on what I can build into the construction that would help, or am I doing what I should now, and need to deal with any other issues when I can get into the room and listen or measure. Do you have any thoughts on the helpfullness of software like REW to tune a room?


----------



## nathan_h




> Quote:
> Originally Posted by *eiger* /forum/post/0
> 
> 
> 
> Thanks Dennis.
> 
> 
> I know it's a tad late. Because it's not new construction, I was limited with existing structure when we moved in. I was afraid you were going to say that. I guess I need to look into how much work it would be. Yes, note the huge vents in HVAC in pics.
> 
> 
> I already freshly painted and textured not long ago, so the thought of adding a layer of drywall to ceiling doesn't thrill me much.
> 
> 
> Here is the room as it stands now.
> 
> 
> GRRR. Shoulda, Coulda, Woulda



Say a little more about what sounds are bothersome outside the theater. Thumping bass? Or are the full range of sounds audible and problematic?


For bass, additional construction is needed and it can be substantial. For higher frequency sounds some strategic surgery on the ducting, outlets, doors might help a bit.


The other alternative, unrelated to work on the room, is to consider using high quality headphones instead of the speakers at the times of day when the loudness might bother other household members. I lived in one place where my method was simple: spouse is watching the movie=use speakers, spouse is sleeping=use headphones.


----------



## eiger




> Quote:
> Originally Posted by *nathan_h* /forum/post/19548341
> 
> 
> Say a little more about what sounds are bothersome outside the theater. Thumping bass? Or are the full range of sounds audible and problematic?
> 
> 
> For bass, additional construction is needed and it can be substantial. For higher frequency sounds some strategic surgery on the ducting, outlets, doors might help a bit.
> 
> .



Nathan -


Right now it's more of the full range that is audible from the upstairs living room. I mentioned it's a split level, 1979 house. living room/kitchen being directly above the HT. HT sits on concrete.


I've identified a couple of problem areas that I would like to address


1) Vents. These are super old vents that were there when we purchased the house. 3 of them in the room. What can be done here? Obviously the room needs to have heat.










2) Door. While the house is old, new doors were put on by previous owner. Home Depot specials, as you can see from picture. One door goes to laundry room, and the other adjacet door goes to stairwell. Lightweight, hollow cheap wood with pretty wide gaps. What are better options for doors?


3) I notice that some people put padded fabric material along their walls. (filled with fiberglass?). Would this help in my situation at all?


----------



## Dennis Erskine




> Quote:
> Dennis, yes...although they can't be open all the time!



...even when closed.


----------



## nathan_h




> Quote:
> Originally Posted by *eiger* /forum/post/19549179
> 
> 
> 
> 
> 1) Vents. These are super old vents that were there when we purchased the house. 3 of them in the room. What can be done here? Obviously the room needs to have heat.



This is beyond my area of knowledge, but I think if you do some searches for "vents" in the construction threads, you may see what people have done. I believe this is the most invasive of these three ideas, but may make a big difference. It would mean tearing into the walls/ceiling at those locations, etc.



> Quote:
> 2) Door. While the house is old, new doors were put on by previous owner. Home Depot specials, as you can see from picture. One door goes to laundry room, and the other adjacet door goes to stairwell. Lightweight, hollow cheap wood with pretty wide gaps. What are better options for doors?



This is relatively easy and effective: Use solid core, exterior grade doors with weather stripping. If you are really lucky, the spaces would accommodate a pre-hung home depot exterior door -- making it less arduous to install.



> Quote:
> 3) I notice that some people put padded fabric material along their walls. (filled with fiberglass?). Would this help in my situation at all?



Not so helpful for preventing sound from escaping, but used in the right places (first reflection points) and of the right thickness (2 to 4 inches) it can greatly improve how the room sounds when you are in it (but don't overdo it). Bass traps, again, which are just bigger batches of insulation, typically in the "corners", will also improve the sound in the room, but not really help with your sound leakage.


-------------


Anyway, these items above won't solve the problem, especially in the bass range, which really is a structural thing, but may improve the situation for you.


----------



## indybrian

OK I have tried the search function but can not find any guidance. I want to make a corner super chunk bass trap. All I was able to purchase locally in Certainteed 300 with the FSK backing. I have found that the FSK is OK to leave on if using a full panel with the air gap behind.


My question is do I need to remove the FSK backing if I am going to stack the triangles?


Thanks.


----------



## Ethan Winer




> Quote:
> Originally Posted by *indybrian* /forum/post/19568208
> 
> 
> do I need to remove the FSK backing if I am going to stack the triangles?



Yes, though you could / should add similar type paper to the new front surface that faces the room.


--Ethan


----------



## indybrian

Thanks Ethan.


I have spent time reading the articles on your website. Thanks for helping us DIY guys.


----------



## llj

Seating area of theater is directly beneath main house hallway.


The good news is the hallway floor/theater ceiling has 1.5 inches of gypcrete in it making it relatively massive. However, footfall noise is quite evident with unfinished theater ceiling.


The theater has a soffit around the perimeter. Initial idea is to drywall the room without the soffit and then apply the soffit on top of the drywall.


Considering clips and channel to isolate the ceiling. However, this means applying the soffit to the isolated ceiling drywall. Two no-nos... Hanging something other than drywall from the clips, and coupling the isolated ceiling to the walls via the soffit.


One potential solution is build the soffit region "normally" without isolation. Isolate only the field region inside the soffit. Don't know impact of not isolating the soffit region.


Comments? Other solutions?


----------



## Jay5298

Hi guys,

I have had my HT for about a year now and plan on adding some accoustical treatments hopefully early next year. I will probably start with bass traps in the corners and early reflections on the walls and ceiling. I have read most of this thread from beginning to end and it's full of information on how to treat a room, but not much talk on how the rooms sound after treating them. I would like to hear from some people that have treated their rooms and what they think it sounds like before and after. Was it worth the time and money spent, and how much better does it sound now? Is it a huge difference or just a minor improvement? I know every room is different and some people put more treatments than others, but if you do the minimum like I plan on doing, will it help enough to notice a difference. When I do plan on treating my room I will post some pictures of my room and hopefully get some advice on what I should do and where. Thanks


----------



## cavchameleon




> Quote:
> Originally Posted by *Jay5298* /forum/post/19584898
> 
> 
> Hi guys,
> 
> I have had my HT for about a year now and plan on adding some accoustical treatments hopefully early next year. I will probably start with bass traps in the corners and early reflections on the walls and ceiling. I have read most of this thread from beginning to end and it's full of information on how to treat a room, but not much talk on how the rooms sound after treating them. I would like to hear from some people that have treated their rooms and what they think it sounds like before and after. Was it worth the time and money spent, and how much better does it sound now? Is it a huge difference or just a minor improvement? I know every room is different and some people put more treatments than others, but if you do the minimum like I plan on doing, will it help enough to notice a difference. When I do plan on treating my room I will post some pictures of my room and hopefully get some advice on what I should do and where. Thanks



Hi Jay,


I think that most here will agree that there is a incredible improvement with their rooms are treated. Mine is small and it made a HUGE difference in every respect: cleaner more detailed bass, non-smearing of the midrange and highs (dialog is much more clear and cymbals are extremely crisp with no ringing), and just much nicer sound over all. I found it to be one of the best improvements to our system - money and time well spent. There is a lot of info on this thread (awesome resource!) and many knowledgeable folks that can guide you through you plans. Have fun with it!


----------



## Jay5298

Quote:

Originally Posted by *cavchameleon* 
Hi Jay,


I think that most here will agree that there is a incredible improvement with their rooms are treated. Mine is small and it made a HUGE difference in every respect: cleaner more detailed bass, non-smearing of the midrange and highs (dialog is much more clear and cymbals are extremely crisp with no ringing), and just much nicer sound over all. I found it to be one of the best improvements to our system - money and time well spent. There is a lot of info on this thread (awesome resource!) and many knowledgeable folks that can guide you through you plans. Have fun with it!
Well, that's the kind of testimonial I was looking for. What size room do you have? Mine is 16.5ftW, 25ftD, 8ftH. I guess that's considered small. My room seems to echo quite a bit it seems like when I listen to music, but I can't hear it as much when watching movies. I just wan't to make sure I'm doing it correctly when I install the treatments, and not putting things where they don't belong.


----------



## sneill

Hi,


Quick question on Rockwool - 23kg vs 60 kg sq m?


I'm building false wall at both ends to reduce sound transmission to my neighbours. (It's an old terraced house in built 1850 in Dublin, Ireland)


Front of room:









Back of room:










Essentially I plan to:

1. throw up some batons on x2 walls touching my neighbours wall (mid terraced house)

2. install Rockwool in the cavities*

3. add resilient bars

4. apply some plaster board

5. and then use Green glue to apply a 2nd layer of plaster board.


* Rockwoll: I have choice of using:


a) Standard 6 inch thick 23kg per sq m

b) RW3 4 inch thick 60Kg per Sq m

* Option B is roughly 2.5 times the cost of A.


Question) is the higher density Rockwool worth the extra expense it or is it overkill when using in conjunction with decoupling & Green glue combination?


----------



## Mike Butny

How does foam corner bass traps compare to other material bass traps?


----------



## Anthony A.

hi everyone, i would like some opinions on my setup and if additional bass trapping will fix the issues im having. my room is 19' long x 15' wide x 8' high. i built everything myself, double drywall, greenglue, oc703 all around the room (42" high), front wall has it floor to ceiling and ceiling. my sub is located in the front right corner. i'm using anthem ARC room correction eq which sounds very good. my question though is in regards to adding corner bass traps to my front wall (superchunk method). basically, the sub sounds amazing when im sitting in the second row of my theater at the rear left corner. that is where i usually sit so everything sounds perfect. but if i move to the rear right side, bass is no where near as powerful. same goes for the primary LP which is closer to the screen. so it seems that bass energy is a lot more powerful at the rear of my theater near the walls, but also in the opposite side of sub placement. will corner bass traps to the front of the room help in any way? unfortunately i can't add anything to the rear of the room.


any suggestions/help?


thanks!


----------



## nathan_h




> Quote:
> Originally Posted by *Mike Butny* /forum/post/19601900
> 
> 
> How does foam corner bass traps compare to other material bass traps?



Better than a few, worse than many. Definitely stay away from anything that is not fire retardant rated and purpose built for acoustics. And you can probably get more impact for the same $$$ using more efficient materials like fiberglass.


Lots of great info in this thread. And for the raw numbers technical comparison: http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## nathan_h




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19602078
> 
> 
> will corner bass traps to the front of the room help in any way?



Probably. Will it be enough that you feel like the situation is solved? It's hard to predict now much it will help without knowing more about the room in a scientific way. If you want to know how much more trapping will help, you'd need to do detailed measurements, and then some math.


Another solution is to consider moving the sub to where it interacts with the room better -- but physics being what they are, that's not likely to be a full solution (single sub, long waves, small room = limited options).


Other ideas:


1. Buy a second sub (or third or even fourth). This evens out the bass response in the room when positioned correctly.


2. I'm not familiar with ARC -- does it correct for a multi-seat area, or for one position? If the latter, you may consider a device like Audyssey, that strives to correct for a multi-seat area instead of for a single location. You don't need to get rid of your current gear to do that. Audyssey via SVS makes an outboard sub EQ system that you can place in line with your current setup.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Mike Butny* /forum/post/19601900
> 
> 
> How does foam corner bass traps compare to other material bass traps?



Foam is much less efficient than either fiberglas or rockwool.


See www.realtraps.com for comparisons or http://forum.studiotips.com/index.ph...4d625053ee43f6 for lots of data.


----------



## Anthony A.




> Quote:
> Originally Posted by *nathan_h* /forum/post/19602241
> 
> 
> Probably. Will it be enough that you feel like the situation is solved? It's hard to predict now much it will help without knowing more about the room in a scientific way. If you want to know how much more trapping will help, you'd need to do detailed measurements, and then some math.
> 
> 
> Another solution is to consider moving the sub to where it interacts with the room better -- but physics being what they are, that's not likely to be a full solution (single sub, long waves, small room = limited options).
> 
> 
> Other ideas:
> 
> 
> 1. Buy a second sub (or third or even fourth). This evens out the bass response in the room when positioned correctly.
> 
> 
> 2. I'm not familiar with ARC -- does it correct for a multi-seat area, or for one position? If the latter, you may consider a device like Audyssey, that strives to correct for a multi-seat area instead of for a single location. You don't need to get rid of your current gear to do that. Audyssey via SVS makes an outboard sub EQ system that you can place in line with your current setup.



thanks for the reply. i had audyssey xt (denon 4310 avr), then got an svs as-eq1 and finally sold them and settled on ARC. ARC does do multi-position measurements just like audyssey and i find it better (atleast in my room with my gear) than audyssey xt and subeq. im already thinking about adding more subs, but since i can only add them to the front soundstage (limited placement), i know there is only so much i can do. that is why im wondering if bass traps will help me.


----------



## pepar




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19603057
> 
> 
> thanks for the reply. i had audyssey xt (denon 4310 avr), then got an svs as-eq1 and finally sold them and settled on ARC. ARC does do multi-position measurements just like audyssey and i find it better (atleast in my room with my gear) than audyssey xt and subeq. im already thinking about adding more subs, but since i can only add them to the front soundstage (limited placement), i know there is only so much i can do. that is why im wondering if bass traps will help me.



It's difficult to have too many corner bass traps.


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/19603136
> 
> 
> it's difficult to have too many corner bass traps.



+1


----------



## Ethan Winer




> Quote:
> Originally Posted by *Mike Butny* /forum/post/19601900
> 
> 
> How does foam corner bass traps compare to other material bass traps?



The problem with most foam bass traps is they're not large enough to work very well.


--Ethan


----------



## Anthony A.




> Quote:
> Originally Posted by *pepar* /forum/post/19603136
> 
> 
> It's difficult to have too many corner bass traps.



okay, then if that is the case, would i mess up any sonics if i have it only on one side of the room? i only have the room to do it on one side of the front wall but could also do the ceiling.


and as an alternative to the superchunk method, could i simply put a 2" thick piece of 0c703 on an angle in the corners or must it be be totally full to the corner?


----------



## pepar




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19603652
> 
> 
> okay, then if that is the case, would i mess up any sonics if i have it only on one side of the room? i only have the room to do it on one side of the front wall but could also do the ceiling.



Put them wherever you can. Floor/wall counts as a corner, too.



> Quote:
> and as an alternative to the superchunk method, could i simply put a 2" thick piece of 0c703 on an angle in the corners or must it be be totally full to the corner?



Yes, though filled are more effective. Some comparative testing here . Do what you can and you will be ahead of the majority.


----------



## scl23enn4m3

In a room with seating up against the rear wall, is making the whole back wall absorbing the best way to go about it?


----------



## pepar

Quote:

Originally Posted by *scl23enn4m3* 
In a room with seating up against the rear wall, is making the whole back wall absorbing the best way to go about it?
Well, for a few reasons seating against a wall is not recommended, but if that's what you need to do, then FOUR INCHES of OC 703 (or equivalent) should be placed on the wall behind the seating.


Jeff


----------



## scl23enn4m3




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Well, for a few reasons seating against a wall is not recommended, but if that's what you need to do, then FOUR INCHES of OC 703 (or equivalent) should be placed on the wall behind the seating.
> 
> 
> Jeff



Thanks for the reply. I know it's not ideal. It's the only way to have a second row with out the viewing distances causing motion sickness though. The only other way is going smaller with the screen. Would moving the back row off the wall like 4 inches be beneficial or does small increments like that not even make a difference?


----------



## erkq




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/19608429
> 
> 
> Thanks for the reply. I know it's not ideal. It's the only way to have a second row with out the viewing distances causing motion sickness though. The only other way is going smaller with the screen. Would moving the back row off the wall like 4 inches be beneficial or does small increments like that not even make a difference?



I'd go with a smaller screen. "Motion sickness" tells me it's too close if you don't move it back. So why not make is smaller rather than move it back? It's all about the angle of view, not the absolute size, anyway. "Motion sickness" tells me the angle of view is too large.


----------



## pepar




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/19608429
> 
> 
> Thanks for the reply. I know it's not ideal. It's the only way to have a second row with out the viewing distances causing motion sickness though. The only other way is going smaller with the screen. Would moving the back row off the wall like 4 inches be beneficial or does small increments like that not even make a difference?



I think you'd need a few FEET to minimize the problems of being too close to a wall. From your description, you're probably limited to a 4" spacing to allow for the absorption. Unless you do away with the second row, or decrease screen size.


Question for ya ... you mean viewing distances being a problem if the second row pushes the first row too close, right?


Jeff


----------



## scl23enn4m3




> Quote:
> Originally Posted by *erkq* /forum/post/19608477
> 
> 
> I'd go with a smaller screen. "Motion sickness" tells me it's too close if you don't move it back. So why not make is smaller rather than move it back? It's all about the angle of view, not the absolute size, anyway. "Motion sickness" tells me the angle of view is too large.



Well the theater is still in it's beginning stages so I'm not sure if the screen would be too big yet.



> Quote:
> Originally Posted by *pepar* /forum/post/19608539
> 
> 
> I think you'd need a few FEET to minimize the problems of being too close to a wall. From your description, you're probably limited to a 4" spacing to allow for the absorption. Unless you do away with the second row, or decrease screen size.
> 
> 
> Question for ya ... you mean viewing distances being a problem if the second row pushes the first row too close, right?
> 
> 
> Jeff



I'd rather get rid of the second row than go with a smaller screen







. And yeah, sorry about not clarifying, that's exactly what I meant.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19603652
> 
> 
> and as an alternative to the superchunk method, could i simply put a 2" thick piece of 0c703 on an angle in the corners or must it be be totally full to the corner?



Make sure to consider alternative "equivalent" insulation options if cost is the big concern - for example, I checked locally, the best I can do for OC 703 2" is $1.18/sf; I can get Roxul AFB 3" for $0.71. Using alternative materials, you might be able to build SuperChunks for the cost of the "span the corner" method. For spanning the corner, you'd want at least 4" (or so I've read).


----------



## nathan_h




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/19610624
> 
> 
> I'd rather get rid of the second row than go with a smaller screen
> 
> 
> 
> 
> 
> 
> 
> . And yeah, sorry about not clarifying, that's exactly what I meant.



Sharing the dimensions of the room -- screen size, and distance to first row and second row, especially -- will help us recommend possible solutions.


But here is the solution I came up with: I said "The second row is for non critical viewing, listening and for other people" so I'll make it decent, but never sit there. Works well, and that second row is still better than what most of my guests are used to.


In my room, too, it was either a second row too close to the wall, or no second row at all.


----------



## scl23enn4m3




> Quote:
> Originally Posted by *nathan_h* /forum/post/19611465
> 
> 
> Sharing the dimensions of the room -- screen size, and distance to first row and second row, especially -- will help us recommend possible solutions.
> 
> 
> But here is the solution I came up with: I said "The second row is for non critical viewing, listening and for other people" so I'll make it decent, but never sit there. Works well, and that second row is still better than what most of my guests are used to.
> 
> 
> In my room, too, it was either a second row too close to the wall, or no second row at all.



You hit the nail on the head. My theater is looking like 11' x 16.5' with a false wall AT screen making the length 15'. Here's the catch though, after sheetrock and carpet the ceiling height is going to be 6'1". Those are as close dimensions as I can get since framing hasn't begun yet. I'll attach pictures of it too. The seating isn't in the right position because I just threw them in there to see how the look would be. Same goes for the paneling.


Also, the left corner (facing the screen) behind the screen will have a corner bass trap. Any ideas on how to treat the nook in the front right corner?



EDIT: That's a 100" 16:9 screen I put in the drawing with extensions on the left and right for 2.35:1 if I want to go with CIH.


----------



## nathan_h

That's a tight fit. My room is approximately 12 by 17 by 7ft tall, and two rows feels on the edge of crowded, and definitely left no room for recliners in row 2. With your height, row 2 may feel very close to the ceiling.


I started with a 10ft wide 2.35:1 screen which was on the edge of too big for the first row. Due to wanting speakers in the room of a certain height and location and type, I have reduced the screen a bit and it still engulfs well, especially in the front row.


So I think you can make that room work but there will be a few tradeoffs.


I'll let others comment on your other questions.


But here's the big question: how critical is row 2? Occasional overflow or always in use because of how many people are typically watching?


By the way, if you haven't already, i'd start a build thread in the construction area since we are getting way off topic for this bread and I think you'll get more construction conversations there.


----------



## PSUHammer

Howdy folks...lots of info here that it is quite overwhelming. I am a relative noob to construction and accoustics. I am building a dedicated HT in the basement (16'x9'x8').


I have an SVS 12" sub and a basic 5.1 setup with mid level Onkyo AVR. The room will be in the corner of the basement (under my kitchen and laundry room) with the walls along the front and side. Two walls (right and rear) will be standard 2x4 framed.


I was going to go berber carpet, standard drywall and drop ceiling. I don't have an unlimited budget but any minor suggestions to help trap bass or sound in the room? Right now, the outer walls are framed and that is about it.


Looking for basic thoughts around: Ceiling tile selection, anything to add behind the drywall?, etc.


THANKS in advance for any tips. I have been looking around the forums and it is hard to come to a consensus for some easy basic do's and don'ts.


PS. If this thread is off topic or better suited for another area, I can delete and repost elsewhere.


----------



## Glenn Baumann




> Quote:
> Originally Posted by *nathan_h* /forum/post/19613681
> 
> 
> That's a tight fit. My room is approximately 12 by 17 by 7ft tall, and two rows feels on the edge of crowded, and definitely left no room for recliners in row 2. With your height, row 2 may feel very close to the ceiling.
> 
> 
> I started with a 10ft wide 2.35:1 screen which was on the edge of too big for the first row. Due to wanting speakers in the room of a certain height and location and type, I have reduced the screen a bit and it still engulfs well, especially in the front row.
> 
> 
> So I think you can make that room work but there will be a few tradeoffs.
> 
> 
> I'll let others comment on your other questions.
> 
> 
> But here's the big question: how critical is row 2? Occasional overflow or always in use because of how many people are typically watching?
> 
> 
> By the way, if you haven't already, i'd start a build thread in the construction area since we are getting way off topic for this bread and I think you'll get more construction conversations there.



Nathan,


What is your eyeball to screen viewing distance for your front row?


I am also considering a 10ft wide 2.35 screen for my 12 ft wide room with a single row viewing distance of 11.5 to 12 feet!


I could also maybe go down to a 9 ft wide screen if necessary!


Your overall impressions please!











...Glenn


----------



## erkq




> Quote:
> Originally Posted by *Glenn Baumann* /forum/post/19616997
> 
> 
> Nathan,
> 
> 
> What is your eyeball to screen viewing distance for your front row?
> 
> 
> I am also considering a 10ft wide 2.35 screen for my 12 ft wide room with a single row viewing distance of 11.5 to 12 feet!
> 
> 
> I could also maybe go down to a 9 ft wide screen if necessary!
> 
> 
> Your overall impressions please!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ...Glenn



I'm not Nathan, but I have a 10 foot wide screen. 2.35 movies work for me from 10' back (1x sw!) but 16:9 is a little overwhelming from there. So I view those from the second row at 16' back.


Neighbors prefer the front row for 2.35 movies.


----------



## nathan_h

Agreed. 1x can work for 235 material. Too big for 16:9. But we are cluttering this topic with non acoustics. So i'll stay quiet going forward.


----------



## KERMIE

If one can only "straddle" the bottom half (2' x 4') of the corners (Floor to half way to ceiling) of the room with a 4" bass trap does the top of the trap have to be sealed? The bottom will be due to it touching the floor.


What would be an alternative to bass trapping if one cannot do a full corner (Floor to ceiling).


Lastly, since subwoofers are usually located on the floor, does bass collect evenly in the lower corners of a room as the upper corners?


Thanks


----------



## Dennis Erskine

Bass doesn't "collect" anywhere. It doesn't seek out corners to go hide in. Bass traps don't "trap" anything. Bass "traps" are absorbers like any other absorber except bigger do deal with the wave lengths of the lower frequencies (at 80Hz the wave length is 14'). Bass absorbers can be installed anywhere you have the depth. Very few bass "traps" or corner "traps" (ever trap and catch a corner?) have much effect below 100 Hz...or at least their performance drops off rapidly below 100 Hz. For low frequencies, diaphragmatic type absorbers work best when near wall boundaries. For example a velocity type (diaphramatic are pressure type absorbers), you'd need a depth ranging from 1.5 to 3' for 80 Hz when mounted on a wall.


----------



## nathan_h




> Quote:
> Originally Posted by *KERMIE* /forum/post/19620618
> 
> 
> If one can only "straddle" the bottom half (2' x 4') of the corners (Floor to half way to ceiling) of the room with a 4" bass trap does the top of the trap have to be sealed?



No.


----------



## Brad Horstkotte

What are my options for adhering unfaced rigid fiberglass panels to the wall behind my screen? I've seen rotofast (too pricey), spray adhesive (may try that), what else have you guys had success with?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Rob67* /forum/post/19614912
> 
> 
> any minor suggestions to help trap bass or sound in the room?
> 
> ...
> 
> PS. If this thread is off topic or better suited for another area, I can delete and repost elsewhere.



This thread is focused on the use of materials within the room to treat frequency response and reverberation. From the question above, it sounds like you may be thinking more about isolation - controlling the amount of sound in the room from being heard outside, and vice versa. For the latter, try posting in the Green Glue thread, or create your own build thread to get advice specific to your build (on any topic).


(then again maybe I misinterpreted your question?)


----------



## Dennis Erskine

Behind the screen you can use a collared nail. Usually the collars are orange and you'll need to blast each of 'em with some black spray paint.


----------



## Brad Horstkotte

Thanks Dennis, I like the sound of that - budget friendly (*cough* cheap *cough*) and locally available.


----------



## PSUHammer




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19629405
> 
> 
> This thread is focused on the use of materials within the room to treat frequency response and reverberation. From the question above, it sounds like you may be thinking more about isolation - controlling the amount of sound in the room from being heard outside, and vice versa. For the latter, try posting in the Green Glue thread, or create your own build thread to get advice specific to your build (on any topic).
> 
> 
> (then again maybe I misinterpreted your question?)



Nope, that's it. Thanks! Sorry for posting OT!


----------



## studlygoorite

Hello People,


First time doing acoustic treatments here and have a question. My first reflective point on my front right speaker has a curtain from a window in the way, the curtain is thick and goes from ceiling to floor. Should I cut the curtains so they just cover the window and allow me to put a panel there, do I put the panel behind the curtain or is the curtain a sufficient absorber?


Thanks, John


----------



## Brad Horstkotte

If the curtain material is fairly porous (passes the "blow test"), you could put the panel behind it. The curtain by itself would not be sufficient (assuming you're putting a panel on the opposing wall).


----------



## tallnick

my DIY acoustic panels.


total cost for 3 panels: $NZ 100.00


feel free to PM me if you want any details on materials, construction, etc.


they work wonderfully and have some serious WAF!


now I just need to convince the wife I need about eight more!


----------



## studlygoorite




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19643128
> 
> 
> If the curtain material is fairly porous (passes the "blow test"), you could put the panel behind it. The curtain by itself would not be sufficient (assuming you're putting a panel on the opposing wall).




I will be placing a panel on the opposing wall, 6 in total, but maybe 5 now if the cutain is good enough. Two on the left wall, one plus the curtain on the right wall and two on the back wall as I sit only 4' from it. I will also be placing bass traps in all 4 corners.


John


----------



## nezff

Hey guys. I would like to know what I could do in my room to cut down on the echoing? Here are some pics of my room. It is 30x15 and has a 4-5 foot wall then it goes up into a vaulted like ceiling. I was thinking of making some panels but had no idea where to put them or how to arrange them. I still want the room to look appealing also. thanks in advance


----------



## studlygoorite

My dealer is trying to sell me an acoustic kit from Cascade Audio but it seems very expensive. Can you tell me if this NRC rating is good?


2"- 250Hz-0.89

-500Hz-1.12

-1000Hz-1.05

-2000Hz-1.04


Thanks, John


----------



## nathan_h




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19651903
> 
> 
> My dealer is trying to sell me an acoustic kit from Cascade Audio but it seems very expensive. Can you tell me if this NRC rating is good?
> 
> 
> 2"- 250Hz-0.89
> 
> -500Hz-1.12
> 
> -1000Hz-1.05
> 
> -2000Hz-1.04
> 
> 
> Thanks, John



"Good" is relative. Relative to what? Relative to other materials, and other prices. Here is the data you need for comparison in terms of performance.

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## nathan_h




> Quote:
> Originally Posted by *nezff* /forum/post/19648147
> 
> 
> Hey guys. I would like to know what I could do in my room to cut down on the echoing? Here are some pics of my room. It is 30x15 and has a 4-5 foot wall then it goes up into a vaulted like ceiling. I was thinking of making some panels but had no idea where to put them or how to arrange them. I still want the room to look appealing also. thanks in advance
> 
> 
> (images deleted to save space)



Cool space. Challenging walls....


I think you want to use the "mirror test" and place panels at the side wall first reflection points -- which are probably on the sloped ceiling. Depending on budget and your interest in experimenting, diffusion might give the room a more open sound. Absorption would get you very good results for less cash, too.


Larger think panels for bass "traps" behind the L and R speakers, and perhaps where the small ceiling hits the front and rear wall (straddling that junction) would probably help a lot, too.


----------



## studlygoorite




> Quote:
> Originally Posted by *nathan_h* /forum/post/19651984
> 
> 
> "Good" is relative. Relative to what? Relative to other materials, and other prices. Here is the data you need for comparison in terms of performance.
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm



Thanks for the link, looks like I've got a lot more reading to do.







Would only like to spend a grand or so not three times that.


John


----------



## nathan_h




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19652094
> 
> 
> Thanks for the link, looks like I've got a lot more reading to do.
> 
> 
> 
> 
> 
> 
> 
> Would only like to spend a grand or so not three times that.
> 
> 
> John



Your other option is to compare the panels your dealer recommends versus the usual suspects online that publish good test data and prices, like GIK Acoustics, RealTraps, etc. Less reading, and good comparisons.


These will tell you quickly whether the price for the performance offered by your dealer is appealing. This won't take into account leveraging you relationship with your dealer, his/her willingness to come to your home for evaluation and installation, etc. Note that the vendors I mention *do* offer consultation, too, as part of the low pressure sales process.


I've worked with both vendors and would do so again.


----------



## Ethan Winer

Quote:

Originally Posted by *nezff* 
I would like to know what I could do in my room to cut down on the echoing?
You'll get a huge improvement from corner bass traps, plus mid/high frequency absorbers at the side-wall and ceiling reflection points. All the usual suspects. This short article explains the basics in plain English:

Acoustic Basics 


--Ethan


----------



## studlygoorite

Quote:

Originally Posted by *nathan_h* 
Your other option is to compare the panels your dealer recommends versus the usual suspects online that publish good test data and prices, like GIK Acoustics, RealTraps, etc. Less reading, and good comparisons.


These will tell you quickly whether the price for the performance offered by your dealer is appealing. This won't take into account leveraging you relationship with your dealer, his/her willingness to come to your home for evaluation and installation, etc. Note that the vendors I mention *do* offer consultation, too, as part of the low pressure sales process.


I've worked with both vendors and would do so again.
Thanks again nathan_h This project has tapped me out and I was just going to go with corner bass traps and absorbers at the reflection points. That's got to make it better than what I've got going now which is nothing but wall to wall carpet and 4 rocker recliners.







I would think after reading around that a 1,000 should cover it.


----------



## Drew_V

I have a general question:


I have a dedicated theater room (see my sig if interested) with no room treatments at the moment. I have been listening to music and watching movies with good results so far. But when I compare the audio quality in my room to my audiophile-grade headphones and also to my car audio system (also fairly high quality), my theater room sounds too muddied and almost dull. If my ears are correct, I'm perceiving a lot of "cover-up" of much of the musical details with reflected waves and somewhat boomy bass.


I don't have a question whether or not room treatments will help. I know they will... in general. But what I do want to know SPECIFICALLY is whether or not it will clear up the muddiness and bring out the musical details. I'm just concerned that it might be my audio setup and not just the room. I guess there's only one way to find out, but since it's about 5 degrees and snowing outside, and I have no workshop inside the house, I'm stuck with the room just as it is until I can get outside in the garage and start making some acoustic panels.


I guess I'm just looking for some specifics on what I can expect to hear with the room treatments in place. I'd like to at least have some peace of mind that my audio system is functioning fine and I just need to clear up all the reflected cross-talk in the room.


Thanks.


----------



## nathan_h

Nice room.


Your audio system will greatly benefit from treatment. It would definitely be the audio upgrade I would select in your situation.


----------



## Dennis Erskine

I would NOT use NRC ratings ... they really don't "say" a lot. In face ... all of those ratings would imply they absorb more sound than they get. Not really....just the way they are measured.


----------



## studlygoorite




> Quote:
> Originally Posted by *Drew_V* /forum/post/19654478
> 
> 
> I have a general question:
> 
> 
> I have a dedicated theater room (see my sig if interested) with no room treatments at the moment. I have been listening to music and watching movies with good results so far. But when I compare the audio quality in my room to my audiophile-grade headphones and also to my car audio system (also fairly high quality), my theater room sounds too muddied and almost dull. If my ears are correct, I'm perceiving a lot of "cover-up" of much of the musical details with reflected waves and somewhat boomy bass.
> 
> 
> I don't have a question whether or not room treatments will help. I know they will... in general. But what I do want to know SPECIFICALLY is whether or not it will clear up the muddiness and bring out the musical details. I'm just concerned that it might be my audio setup and not just the room. I guess there's only one way to find out, but since it's about 5 degrees and snowing outside, and I have no workshop inside the house, I'm stuck with the room just as it is until I can get outside in the garage and start making some acoustic panels.
> 
> 
> I guess I'm just looking for some specifics on what I can expect to hear with the room treatments in place. I'd like to at least have some peace of mind that my audio system is functioning fine and I just need to clear up all the reflected cross-talk in the room.
> 
> 
> Thanks.



I'm no expert but I have the same problem as you, my car sounds great, nice punch to the chest, I have spent 40,000 on my theatre room and it is still lacking as I know I need treatments and I know it will clean the sound up, nice tight bass and clearer mids and highs are on the way. The position of the subs is also very important as I have been tinkering with this for quite some time as I have run out of cash and can't afford to get an acoustic engineer in here.


John


----------



## studlygoorite




> Quote:
> Originally Posted by *Drew_V* /forum/post/19654478
> 
> 
> I have a general question:
> 
> 
> I have a dedicated theater room (see my sig if interested) with no room treatments at the moment. I have been listening to music and watching movies with good results so far. But when I compare the audio quality in my room to my audiophile-grade headphones and also to my car audio system (also fairly high quality), my theater room sounds too muddied and almost dull. If my ears are correct, I'm perceiving a lot of "cover-up" of much of the musical details with reflected waves and somewhat boomy bass.
> 
> 
> I don't have a question whether or not room treatments will help. I know they will... in general. But what I do want to know SPECIFICALLY is whether or not it will clear up the muddiness and bring out the musical details. I'm just concerned that it might be my audio setup and not just the room. I guess there's only one way to find out, but since it's about 5 degrees and snowing outside, and I have no workshop inside the house, I'm stuck with the room just as it is until I can get outside in the garage and start making some acoustic panels.
> 
> 
> I guess I'm just looking for some specifics on what I can expect to hear with the room treatments in place. I'd like to at least have some peace of mind that my audio system is functioning fine and I just need to clear up all the reflected cross-talk in the room.
> 
> 
> Thanks.




Here is a video of different kinds of music playing in a treated room compared to a non treated room to a partially treated room. Gives you a good idea of what treatments will do.


John

http://www.realtraps.com/video_hearing.htm


----------



## Drew_V




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19655686
> 
> 
> Here is a video of different kinds of music playing in a treated room compared to a non treated room to a partially treated room. Gives you a good idea of what treatments will do.
> 
> 
> John
> 
> http://www.realtraps.com/video_hearing.htm




Thanks for the link. I had gone through the RealTraps website before but did not dig into the videos. Very enlightening.


I believe the treatments will definitely help "cure" my room of some of the inaccuracies that I'm hearing in the music. Some of the audio comparisons in the video sound similar to what I'm hearing in my own room.


----------



## scoobygt68

So I watched that video and noticed something interesting. Their corner bass traps dont straddle the corner but instead lay flush in the corner with a trap being a single flat piece placed flush against the wall and another trap placed flush against the ajoining wall each butted up to each other in the corner. Im planning to put in some bass traps over the Christmas break and was going to simply use 4" thick Owens Corning 705 (probably 2 2" thick piece placed together) straddling each corner of my room, similar to the example of bass traps given by Ethan Winer in his article -

http://www.ethanwiner.com/acoustics.html 


I was under the impression that straddling the corner with the trap, and creating the gap behind the trap between it and the wall was more benefitial than simply having the traps flush against the walls in the corner? .


Also I was curious if anyone was aware of the effectiveness of Roxul Rockboard 60? It looked like a cheaper alternative to using Owens Corning 705.


----------



## nathan_h

The bob gold link in my earlier post will let you compare the relative effectiveness of each material.



> Quote:
> Originally Posted by *studlygoorite* /forum/post/0
> 
> 
> 
> I'm no expert but I have the same problem as you, my car sounds great, nice punch to the chest, I have spent 40,000 on my theatre room and it is still lacking as I know I need treatments and I know it will clean the sound up, nice tight bass and clearer mids and highs are on the way. The position of the subs is also very important as I have been tinkering with this for quite some time as I have run out of cash and can't afford to get an acoustic engineer in here.
> 
> 
> John



There are all sorts of price ranges for acoustic analysis. For a few hundred bucks you can get an expert in there. Will it be the same as a $5k analysis, no. Will it get you 80% of the way there, probably. To choose one name almost at random, consider AccuCal (username umr), as one example.


And of course most of the online vendors will do an analysis remotely for free. You tell them the dimensions and layout of the room, include a few photos, and they can make recommendations that will get you more than half way to nirvana. This is what I did, and then had the chance for an expert with high end tools and solid experience to visit and measure -- and while he found some setup errors in my pre-pro he also said that the room treatment and acoustics were in the perfect range (ie further changes would be about taste and not accuracy) in terms of decay and response etc.


----------



## Ethan Winer




> Quote:
> Originally Posted by *scoobygt68* /forum/post/19656956
> 
> 
> So I watched that video and noticed something interesting. Their corner bass traps dont straddle the corner but instead lay flush in the corner with a trap being a single flat piece placed flush against the wall and another trap placed flush against the ajoining wall



Straddling corners is best, but in that video I wanted to make the point that with enough traps you can get excellent results even if they're flat against the wall. Some people cannot straddle corners due to spouse (or their own) appearance concerns. And in very small rooms straddling impinges much more on the available space. This video was also meant to demo our high-end Modular system where no holes are needed in the walls either.


--Ethan


----------



## Drew_V

Can someone give me some ideas/advice on how I can add a bass trap to this corner? It's the one in the rear left corner where the rack door panel is located. I have about 2-1/2" between the side edge of the door panel and the rear wall.












My first idea is just to put a normal acoustic panel made from 2-inch OC703 and lay it flat against the rear wall. The rack door panel is also made from 2-inch OC703, so that would give me 2 feet on either side of the corner, but only 2 inches thick and not straddling the corner.


I was also considering making a hinged swing-away panel from 4-inch OC703, but it would be complicated and might interfere with my back wall surrounds (if I ever decide to mount them there).


Will I really notice a difference in sound quality of the room if I treat only 3 corners of the room properly and 1 corner "not quite" properly, rather than treating all 4 corners perfectly?


----------



## nathan_h

More importent than symmetrical bass trapping would be thicker bass trapping, IMO.


----------



## Tup

I'm looking to improve my small room sound quality as well. Are there any cheap and easy solutions that will help? I see lots of pictures of theater rooms with sound absorbing panels mounted like artwork on the wall. I have high ceilings and lots of walls that could easily have something like this mounted.


It seems to me that some of the online stores that make custom projector screens could also make some custom sound traps. The commercial places like realtraps.com seem quite expensive.


So can I make some of these sound absorbing panels to help deaden the reflections.


I found some online...
http://www.atsacoustics.com/cat--ATS...nels--109.html 


Any other suggestions?


----------



## nathan_h

You mean recommendations other than those in this thread, like realtraps, Gik acoustics, etc? There are also diy alternatives in this thread, to save some bucks, though I can tell you from personal experince that for a handful of panels the cost savings only add up if you are super quick and handy or value your time at zero.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/19684281
> 
> 
> You mean recommendations other than those in this thread, like realtraps, Gik acoustics, etc? There are also diy alternatives in this thread, to save some bucks, though I can tell you from personal experince that *for a handful of panels the cost savings only add up if you are super quick and handy or value your time at zero.*



Everybody makes that calculation differently. I am handy with tools, am anything but quick and value my time at a lot more than zero. But still, spending a few hundred dollars on 48 cubic feet of 703 and making thousands of dollars worth of superchunk traps and first reflection point absorbers was a ... no-brainer. IMO.


----------



## scoobygt68

So I was looking into 4" thick pyramid foam and was wondering if it would work for bass traps. It has an overall NRC of 0.93 and I could build a wood frame to attach the foam to and put in each corner of my room. I was planning to buy some 705 or some rockboard 60 to use but this pyramid foam looks like it would work as well and would require as much work. Any thoughts?

I found a good price on the stuff here :
http://www.thefoamfactory.com/acoust...ramidfoam.html


----------



## nezff




> Quote:
> Originally Posted by *scoobygt68* /forum/post/19690414
> 
> 
> So I was looking into 4" thick pyramid foam and was wondering if it would work for bass traps. It has an overall NRC of 0.93 and I could build a wood frame to attach the foam to and put in each corner of my room. I was planning to buy some 705 or some rockboard 60 to use but this pyramid foam looks like it would work as well and would require as much work. Any thoughts?
> 
> I found a good price on the stuff here :
> http://www.thefoamfactory.com/acoust...ramidfoam.html



that stuff looks good, Im wondering the same thing. good find


----------



## pepar

I have seen this answered before and the answer is NO for closed cell foam.


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/19691245
> 
> 
> I have seen this answered before and the answer is NO for closed cell foam.



so you are saying that this stuff will not work for acoustic panels?


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/19691407
> 
> 
> so you are saying that this stuff will not work for acoustic panels?



I did notice that the menu/navigation bar (upper left) mentioned both "closed cell" and "open cell." But it wasn't clear what product was being pointed to by the link.


Jeff


----------



## smokarz

looking to build panels for a 'work in progress' movie room.


would appreciate any details on builds with OC 703 (_or are there newer/better materials in the market today?)_



thanks


----------



## Ethan Winer




> Quote:
> Originally Posted by *scoobygt68* /forum/post/19690414
> 
> 
> I found a good price on the stuff here :
> http://www.thefoamfactory.com/acoust...ramidfoam.html



That place is a fraud. The foam they sell is not acoustic quality, and the numbers they show for absorption data are fraudulent. I measured a set of their corner foam bass traps a few years ago in an acoustics lab, and the proof is on my company's Product Data page. See the first two graphs on this page:

http://www.realtraps.com/data.htm 


This company's data claims performance as good as Auralex foam, and you can see that's a lie in these graphs. Not that Auralex foam is very good at bass frequencies either.


--Ethan


----------



## Brad Horstkotte

Thought I'd share this in case anyone in the Los Angeles / Orange County area is looking for suppliers of rigid fiberglass insulation and the like for DIY acoustic treatments - I highly recommend:


MacArthur Company

1324 South Allec St.

Anaheim CA 92805

Justin Grannum

(714) 262-4431
www.MacARTHURCO.com 


They have unfaced 1" and 2" OC 703 in stock ($0.68/sf and $1.36/sf respectively), I also ordered 3" Roxul AFB (Acoustical Fire Batts $0.71/sf, so a cheap effective alternative for SuperChunks) which took less than a week to get. Justin was very responsive and helpful even though my orders were no doubt small potatoes compared to the usual commercial orders. Also worth noting is you can get the OC 703 by the individual 4x8 sheet, don't have to buy by the full bundle. They even hung around 1/2 hour past their usual closing time to process my order and get my Mini Cooper Clubman fully stuffed.


The other local suppliers I contacted either didn't respond at all, or didn't show much interest in helping me. (CWCI Insulation, a-m-s.com).


----------



## Ethan Winer

You do your vendor friend a disservice by posting his email address in a public forum. That's one way spammers find email addresses. Please remove that and replace it with a link to his company's Contact page etc.


--Ethan


----------



## pepar

Good advice. And while I feel that it is OK to mention a positive experience with a vendor, I do not feel that it is OK to dis vendors .. regardless of how _dis_appointing one's experience was with them.


My $.02.


Jeff


----------



## scoobygt68

Im looking at putting bass traps in the corners of my room. Going to use atleast 4 in thick traps.... I gave a 7.5 ft tall ceiling and was wanting to go floor to ceiling however the acoustic fiberglass boards are only 48 inches in height. So if I only use a 48 in tall trap in each corner is that essentially defeating the purpose of putting traps in the corners?


----------



## pepar




> Quote:
> Originally Posted by *scoobygt68* /forum/post/19706385
> 
> 
> Im looking at putting bass traps in the corners of my room. Going to use atleast 4 in thick traps.... I gave a 7.5 ft tall ceiling and was wanting to go floor to ceiling however the acoustic fiberglass boards are only 48 inches in height. So if I only use a 48 in tall trap in each corner is that essentially defeating the purpose of putting traps in the corners?



You can cut the "boards."










Jeff


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19703015
> 
> 
> You do your vendor friend a disservice by posting his email address in a public forum.



Point taken, e-mail address removed. BTW, not a friend of mine, just a guy who was helpful and I felt like supporting them.



> Quote:
> Originally Posted by *pepar* /forum/post/19703064
> 
> 
> And while I feel that it is OK to mention a positive experience with a vendor, I do not feel that it is OK to dis vendors .. regardless of how _dis_appointing one's experience was with them.



Well we'll just have to disagree there - others may have better luck with them than I did, they have many offices and maybe I just caught them on a bad day. I don't think my comments are unfair at all.


----------



## klpham71

Hi,


I am wondering if using the 3 LCR on-wall speakers, does the front wall need to be treated? The screen, by the way, is non-AT. Thank you for your response.


Keith.


----------



## Emig5m

I posted this over in the Tweaks and Do-It-Yourself forums but didn't get a response (wasn't aware of this thread when I posted and that forum doesn't see much traffic). But can you use 6lb rebond carpet padding for DIY acoustic panels? They use this same type of material in speaker cabinets and I have tons of the stuff laying around not to mention I can get it for free from a friend that owns a carpeting business. My budget is pretty low since I'm laid off work for the winter so it's this or nothing - waste of time? *Seems like it would absorb sound good since when my friend installed the padding before the carpet I noticed a dramatic change in the sound of our voices right away.*


----------



## Drew_V




> Quote:
> Originally Posted by *Emig5m* /forum/post/19719627
> 
> 
> I posted this over in the Tweaks and Do-It-Yourself forums but didn't get a response (wasn't aware of this thread when I posted and that forum doesn't see much traffic). But can you use 6lb rebond carpet padding for DIY acoustic panels? .




Honestly, I like that idea. The density seems good -- the same as OC703. So I guess I can't see why it wouldn't work. And you're right, if it's good enough of an absorber for the floor, why not the walls?


I have a bunch of leftover padding (can't remember if it's 6 or 8 lb.), so I might try making up some panels with it. Since it's pretty thin (around 1/2"), you'd have to stack up several layers of it. But I wonder if you could also separate the layers, leaving a 1/2" air gap between them, to make them more effective?


Definitely not a bad idea to try. But maybe someone already has tried it and found that it's not as good as other options. I'm definitely interested to find out.


EDIT: Another idea might be to suspend the stuff inside a frame so that it acts sort of like a dampener, since it's pretty flexible. Seems like there might be a good application of this stuff if enough experimentation was done...


----------



## Emig5m




> Quote:
> Originally Posted by *Drew_V* /forum/post/19720365
> 
> 
> Honestly, I like that idea. The density seems good -- the same as OC703. So I guess I can't see why it wouldn't work. And you're right, if it's good enough of an absorber for the floor, why not the walls?
> 
> 
> I have a bunch of leftover padding (can't remember if it's 6 or 8 lb.), so I might try making up some panels with it. Since it's pretty thin (around 1/2"), you'd have to stack up several layers of it. But I wonder if you could also separate the layers, leaving a 1/2" air gap between them, to make them more effective?
> 
> 
> Definitely not a bad idea to try. But maybe someone already has tried it and found that it's not as good as other options. I'm definitely interested to find out.



Wonder how many layers to stack it? Total thickness? So if it's 1/2" thick, maybe three to four layers thick? And how to attach the layers, fabric glue same as whatever fabric covering you put over it? Now do you have to use actual grill cloth or can you buy acoustically transparent fabric at a fabric place for cheaper? (to match the color of the wall where as speaker grill cloth is normally only black or brown). I know all under padding isn't the same, got some cheap crap from home depot one time for another room that actually looked 3/4" thick but wasn't that soft to walk on or didn't have the same effect on sound as this 6lb rebond stuff my friend used. I could of been happy just by the feel of this underpadding without carpet at all, lol, he definitely uses some quality material.


My sound system is in a temp room right now while I clear out and clean up the main room (new paint, carpet, furniture, etc) but I suppose I could make a few test panels in my current room. I know my kitchen needs the most acoustic lovin' (it's so damned echoey in there with the laminate flooring) - maybe that would be the room to try out the carpet under padding sound panels? Gonna grab my wall color sample see if I can find some color matched acoustically transparent fabric, if not, maybe something artful...


----------



## nezff

I found some thick cotton insulation that will work for acoustic panels. Ultratouch and QuietBatt are their names.


----------



## Drew_V




> Quote:
> Originally Posted by *Emig5m* /forum/post/19720505
> 
> 
> Wonder how many layers to stack it? Total thickness? So if it's 1/2" thick, maybe three to four layers thick? And how to attach the layers, fabric glue same as whatever fabric covering you put over it?





About the only thing I can suggest is that you try it out after building up your panels out of the padding in various thicknesses, ranging between 1" and 2" for side walls and 4" for corners.


A quick internet search turned up basically nothing regarding actual data for carpet padding, but the only objections that I ran across were just that the carpet pad is relatively thin. Well, duh. But when you stack 4 pieces of 1/2" carpet padding on top of each other, we're talking about serious damping.


And as I said, if you suspend pieces within a frame so that they can actually "yield" a little bit as the sound waves impinge upon them, I suspect they might actually be more effective than fiberglass panels of the same thickness. Maybe TOO effective, who knows.


Anyways, if you have the stuff laying around, it's definitely worth a shot. I have about 20 yards of it sitting in my basement as well, so I'll probably try it myself, eventually.


----------



## Emig5m




> Quote:
> Originally Posted by *Drew_V* /forum/post/19722471
> 
> 
> About the only thing I can suggest is that you try it out after building up your panels out of the padding in various thicknesses, ranging between 1" and 2" for side walls and 4" for corners.
> 
> 
> A quick internet search turned up basically nothing regarding actual data for carpet padding, but the only objections that I ran across were just that the carpet pad is relatively thin. Well, duh. But when you stack 4 pieces of 1/2" carpet padding on top of each other, we're talking about serious damping.
> 
> 
> And as I said, if you suspend pieces within a frame so that they can actually "yield" a little bit as the sound waves impinge upon them, I suspect they might actually be more effective than fiberglass panels of the same thickness. Maybe TOO effective, who knows.
> 
> 
> Anyways, if you have the stuff laying around, it's definitely worth a shot. I have about 20 yards of it sitting in my basement as well, so I'll probably try it myself, eventually.



I just need to find a place locally that sells acoustically transparent fabric hopefully in the color I need which is basically an olive. Is there a way to tell which type of fabric will work and which wont? I know there's probably a million places online, but I really want to shop locally and make these tomorrow. Nothing I seen at Walmart looked like it would work for sound transparency (or even the color I want). I'm going to call a local arts and crafts store tomorrow that sells a ton of different fabrics and see what they have.


I suppose the nice thing about tweaking with layers is that you can tailor to the room needs? For instance, if the room is already pretty well dampened with thick stuffed furniture and wall to wall carpet, maybe only go two layers thick and then in a real echoey room maybe bump it up to four + layers for each panel? I'm going to start with probably three layers.


Still curious how exactly to go about making corner bass traps with it? Make a frame out of 1"x1"s 1' square, wrap with chicken wire to hold the padding, stuff it with the padding, and then wrap in fabric? Got the idea from a local B&W dealer in which they had these corner bass traps that where square in shape and went up and down the entire length of the wall from floor to ceiling.


----------



## Brad Horstkotte

For fabrics, try Joanne's if there's one near you.


For the superchunk style corner trap, what I'm doing is using 2x2s screwed/liquid nailed at 17" from the corners, which should keep the 24" triangles in place. Then cover with fabric and trim.


----------



## scoobygt68

I have a question about putting bass traps in the same corners as a subwoofer. Im ordering some bass traps and panels this week and Im planning to put bass traps from floor to ceiling in my front corners of my room. The left front corner has a large sub. Will the sub be hindered by having the bass trap behind it?

Im also putting a couple acoustic panels at the first reflection points.


----------



## Brad Horstkotte

I posted a reply but somehow it disappeared - anyway, a sub near a corner trap is fine - below 80 Hz won't get absorbed much at all by traps unless they are VERY deep (several feet).


----------



## studlygoorite

I wonder if anyone in here can answer this?


I have installed Acoustic panels and bass traps and have lots of power and expensive speakers with two 15" Paradigm Servo Subs. My room is 16'X21' and I am missing my kick from my bass, when I play a test tone of 100hz I can hardly hear it from my seat but when I stand up it is very loud. Any way I can get that frequency down to my seating area?


Thanks John


----------



## pepar




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19768114
> 
> 
> I wonder if anyone in here can answer this?
> 
> 
> I have installed Acoustic panels and bass traps and have lots of power and expensive speakers with two 15" Paradigm Servo Subs. My room is 16'X21' and I am missing my kick from my bass, when I play a test tone of 100hz I can hardly hear it from my seat but when I stand up it is very loud. Any way I can get that frequency down to my seating area?
> 
> 
> Thanks John



Raise your seating area.










Yep, your present one seems like it is in a null for that frequency. You try moving the subs around to smooth out the response, and you could (probably) benefit from more bass traps.


Where are your subs now, what are your room dimensions and where/what are your bass traps?


Jeff


----------



## CatBrat

Try the sub-crawl. It's where you put the sub where you sit. Play something that has a lot of bass. Then you get low, such as on your knees and you crawl around the room and you mark those spots where the bass sounds the best. Them move your sub to one of those spots.


With the 2nd sub, I would choose another spot in the room where bass is lacking and do the same thing for that spot.


----------



## pepar

Actually, with a rectangular room it is best to place one sub mid-wall (front or side) and the other sub on the opposite wall....


----------



## smokarz

Quote:

Originally Posted by *pepar* 
Actually, with a rectangular room it is best to place one sub mid-wall (front or side) and the other sub on the opposite wall....
hmm...interesting.


my room is 13'x24', and sitting position is 14' away. i currently have the sub upfront with my mains.


so you're suggesting i should put the sub a little closer to the sitting position?


should the sub be facing the listening position, or facing the adjacent wall?


----------



## A9X-308

The reason for the midwall position is explained in the second paper here .


----------



## studlygoorite

Quote:

Originally Posted by *pepar* 
Raise your seating area.










Yep, your present one seems like it is in a null for that frequency. You try moving the subs around to smooth out the response, and you could (probably) benefit from more bass traps.


Where are your subs now, what are your room dimensions and where/what are your bass traps?


Jeff
Boy did I post it the right place or what?










I have been dickin around with this for 2 years. I have rebuilt my room to try and achieve audio bliss, it used to be square 22'X22' now it is 16'X21, put up acoustic panels and bass traps. The bass traps are 2'X4' and 2" thick triangles from Cascade Audio in all upper corners, I have moved my subs about 15 times and run ARC with my Anthem Statement D2v more than that. I have a 142" screen at the front wall which only leaves 2' on either side so not much room for the subs but I did try them there. I sit near the back wall about 4' from it in the middle. The best place I found for my subs is at arms length at either side of me pointing towards the front because it is the only place I get some punch with loud music, all other places including the side wall pointing in do not give me this punch but for example, the side walls give me the best graph and deeper bass but no punch. I have not done the crawl test as I thought I have experimented already with every available spot but I will try it. My ceiling is only 7' high with a beam going across the middle that is 10" down and 20" wide, I thought maybe this is what is giving me my problems in that it was causing my bass to stay up near the ceiling. My floor is carpeted wall to wall and am up for any suggestions. It's still the sub positions that I have to work at is it?


Thanks, John


----------



## studlygoorite

Quote:

Originally Posted by *CatBrat* 
Try the sub-crawl. It's where you put the sub where you sit. Play something that has a lot of bass. Then you get low, such as on your knees and you crawl around the room and you mark those spots where the bass sounds the best. Them move your sub to one of those spots.


With the 2nd sub, I would choose another spot in the room where bass is lacking and do the same thing for that spot.


I will try this thanks CatBrat.


----------



## moreilly

I'm sure it has been posted many times before but what is the best screen wall acoustical treatment material (that is available in Canada) when using an AT screen? And where would be a good place to purchase it?

-Marc


----------



## Brad Horstkotte

Linacoustic is the material I see used most often - nice because its black, has a coating on the face to keep fibers from floating about, and comes in rolls so fewer seams to deal with. Check the jm (Johns Manville) site for local distributors.


I couldn't find it locally myself for a decent price, so went with OC 703, and will cover with cheap fabric. Linacoustic was 5x as expensive locally for me, weird - although not too bad at fabricmate.com if the shipping costs didn't kill it.


----------



## pepar




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19769646
> 
> 
> Boy did I post it the right place or what?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have been dickin around with this for 2 years. I have rebuilt my room to try and achieve audio bliss, it used to be square 22'X22' now it is 16'X21, put up acoustic panels and bass traps. The bass traps are 2'X4' and 2" thick triangles from Cascade Audio in all upper corners, I have moved my subs about 15 times and run ARC with my Anthem Statement D2v more than that. I have a 142" screen at the front wall which only leaves 2' on either side so not much room for the subs but I did try them there. I sit near the back wall about 4' from it in the middle. The best place I found for my subs is at arms length at either side of me pointing towards the front because it is the only place I get some punch with loud music, all other places including the side wall pointing in do not give me this punch but for example, the side walls give me the best graph and deeper bass but no punch. I have not done the crawl test as I thought I have experimented already with every available spot but I will try it. My ceiling is only 7' high with a beam going across the middle that is 10" down and 20" wide, I thought maybe this is what is giving me my problems in that it was causing my bass to stay up near the ceiling. My floor is carpeted wall to wall and am up for any suggestions. It's still the sub positions that I have to work at is it?
> 
> 
> Thanks, John



Bass doesn't collect in certain places or avoid places around the room. It is everywhere, but does positively add and negatively cancel at certain frequencies at certain spots in the room based on room geometry. That is why "bass" sounds loud somewhere and can't be heard other places, but it is not all frequencies ... just certain ones. But if one is the frequency of a bass drum, it is easy to think that all bass is lacking somewhere.


If I read your bass trap dimensions correctly, I would not be able to consider them big enough to actually do much trapping. Effective bass traps are sizable. Click on the home theater link in my sig and look for the section on the traps I build and installed.


By moving the subs you can achieve smoother response, and traps and a good room correction technology can ice it.


Jeff


----------



## studlygoorite




> Quote:
> Originally Posted by *pepar* /forum/post/19770930
> 
> 
> Bass doesn't collect in certain places or avoid places around the room. It is everywhere, but does positively add and negatively cancel at certain frequencies at certain spots in the room based on room geometry. That is why "bass" sounds loud somewhere and can't be heard other places, but it is not all frequencies ... just certain ones. But if one is the frequency of a bass drum, it is easy to think that all bass is lacking somewhere.
> 
> 
> If I read your bass trap dimensions correctly, I would not be able to consider them big enough to actually do much trapping. Effective bass traps are sizable. Click on the home theater link in my sig and look for the section on the traps I build and installed.
> 
> 
> By moving the subs you can achieve smoother response, and traps and a good room correction technology can ice it.
> 
> 
> Jeff



Thanks for your replies pepar, nice set up, I will add more/better bass traps and tinker with the subs placements.


----------



## Brad Horstkotte

I've heard several times from the usual suspects (gurus) that bass traps need to be at least 4" thick, 6" better - if those tri-corner traps are only 2" thick, and if the corner behind them is empty, I'd stuff those pockets with standard pink fluffy insulation.


----------



## studlygoorite

For now, could I double up on some extra 1'X5'X2" thick panels? If I double up on the panels and place them along the back wall straddling the ceiling this should help correct?


John


----------



## pepar

studly, read the information here .


----------



## studlygoorite




> Quote:
> Originally Posted by *pepar* /forum/post/19774582
> 
> 
> studly, read the information here .



Nice, thanks again pepar.


----------



## studlygoorite




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19771140
> 
> 
> I've heard several times from the usual suspects (gurus) that bass traps need to be at least 4" thick, 6" better - if those tri-corner traps are only 2" thick, and if the corner behind them is empty, I'd stuff those pockets with standard pink fluffy insulation.



I do like the looks of them and appreciate your input, I think I'll form some Roxul RXT 80 to sit in behind them and then put more RXT 80, 4 to 6" thick, along the front and back walls where they meet the ceiling. With this and possibly better locations for my subs hopefully I can get the sound that I paid for.










John


----------



## laychooba

hey guys.


i've been toying with the idea of going with some acoustical treatment

in my room. i've been reading up, looking at the OC703 options for some

DIY style setup. the only problem is that my room isn't really traditionally shaped. i don't have closed walls on one side, and the other side there is a

door and a non flat wall.


i tried the mirror trick, but where i see the speaker reflection, i can't

really place a panel on the wall because there's nowhere to put it.


i've enclosed some pics of my setup, does anyone have some advice for

me for what i can do? bass traps, panels, etc.


thanks!




















link to the whole gallery.

http://www.blu-ray.com/community/gal...mber=laychooba


----------



## pepar

Can't tell exactly where, but look up. The ceiling is a reflection point. And it wouldn't hurt to treat the right side wall above the piece of furniture there .. and then do a similar area on the left side for symmetry.


One big MUST DO to treat this room would be 4" of 703 on the rear wall behind the heads of people sitting on the couch (against the wall).


Just my $.02.


Jeff


----------



## pepar

Can't tell exactly where, but look up. The ceiling is a reflection point. And it wouldn't hurt to treat the right side wall above the piece of furniture there .. and then do a similar area on the left side for symmetry.


One big MUST DO to treat this room would be 4" of 703 on the rear wall behind the heads of people sitting on the couch (against the wall). Fallback would be 2", but bass will be very big for anybody sitting there ... and I mean "big" in a not good way.


Just my $.02.


Jeff


----------



## Anthony A.

hi everyone, i wanted some advice as to the addition of rear bass traps for my room. take a look here for pics or what im talking about.

http://www.avsforum.com/avs-vb/showt...1164966&page=4 



basically, my 2nd row is about 15" away from the rear wall and since the room already has 1" of OC703 4' high around the room, im wondering if adding superchunk bass traps behind the 2nd row seating. it won't be visible unless you look behind the seat and will probably be about 10' long x 2' high (off the floor). the trap will be spaced about 2' away from each side wall but will butt up against the lower portion of the rear wall. will this do anything for bass trapping?


----------



## nathan_h




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19790526
> 
> 
> will this do anything for bass trapping?



Yes.


----------



## kevinzoe




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19790526
> 
> 
> hi everyone, i wanted some advice as to the addition of rear bass traps for my room. take a look here for pics or what im talking about.
> 
> http://www.avsforum.com/avs-vb/showt...1164966&page=4
> 
> 
> 
> basically, my 2nd row is about 15" away from the rear wall and since the room already has 1" of OC703 4' high around the room, im wondering if adding superchunk bass traps behind the 2nd row seating. it won't be visible unless you look behind the seat and will probably be about 10' long x 2' high (off the floor). the trap will be spaced about 2' away from each side wall but will butt up against the lower portion of the rear wall. will this do anything for bass trapping?





Hi Anthony,

Kevin in TO here. How are you? Did you ever get the Empire Epik subs we communicated previously about?


About your question, if you have only 15" between the back wall and the rear row of chairs, have you considered a diaphragmatic-type bass trap instead of the 'super chunks?' As you already are using 1" OC around the room I would hazard to guess that the RT60 is pretty low for the upper frequencies so the last thing you probably want is to reduce it further with more fiberglass super chunks. Moreover, fiberglass traps need to be thick to work really well - placement of a fiberglass trap out 15" from your back wall would work most effectively for a 226Hz wavelength (1130/226*12*0.25=15") as 15" equates to the 25% mark of the 264Hz wavelength where particle speed is maximized.


I'd be inclined to consider the diaphragmatic type trap that works where pressure is maximized not particle speed so this type of trap hangs right on your back wall and is about 4" thick. Check out RPG which makes them and you can order them here in Toronto.


Hope that helps somewhat. . .


----------



## smokarz

hey guys, what type of fabrics do you get from JoAnnes to use for panels? thanks


----------



## pepar

The quick test is to see if you can blow through it. If you can, then it should be acoustically transparent enough to allow the sound pass to the absorption. Fabric from a fabric shop is NOT suitable to put speakers behind. For that some bona fide acoustically transparent cloth like from Guilford of Maine, a.k.a. GOM. Some of us use the GOM to cover panels as well, but there less expensive (!) alternatives for covering panels.


Jeff


----------



## studlygoorite

Quote:

Originally Posted by *kevinzoe* 
Hi Anthony,

Kevin in TO here. How are you? Did you ever get the Empire Epik subs we communicated previously about?


About your question, if you have only 15" between the back wall and the rear row of chairs, have you considered a diaphragmatic-type bass trap instead of the 'super chunks?' As you already are using 1" OC around the room I would hazard to guess that the RT60 is pretty low for the upper frequencies so the last thing you probably want is to reduce it further with more fiberglass super chunks. Moreover, fiberglass traps need to be thick to work really well - placement of a fiberglass trap out 15" from your back wall would work most effectively for a 226Hz wavelength (1130/226*12*0.25=15") as 15" equates to the 25% mark of the 264Hz wavelength where particle speed is maximized.


I'd be inclined to consider the diaphragmatic type trap that works where pressure is maximized not particle speed so this type of trap hangs right on your back wall and is about 4" thick. *Check out RPG which makes them and you can order them here in Toronto*.


Hope that helps somewhat. . .
Might you have a link to where you can order these from Toronto? I went to the RPG link and Canada is not an option. Thanks


----------



## pepar

Quote:

Originally Posted by *studlygoorite* 
Might you have a link to where you can order these from Toronto? I went to the RPG link and Canada is not an option. Thanks
I don't think RPG sells to consumers .. only through their distributor/dealer network. At least I can't find on their site where they do e-commerce.


Using the where to buy feature, I see only BC and AB vendors listed.


----------



## smokarz

Quote:

Originally Posted by *pepar* 
The quick test is to see if you can blow through it. If you can, then it should be acoustically transparent enough to allow the sound pass to the absorption. Fabric from a fabric shop is NOT suitable to put speakers behind. For that some bona fide acoustically transparent cloth like from Guilford of Maine, a.k.a. GOM. Some of us use the GOM to cover panels as well, but there less expensive (!) alternatives for covering panels.


Jeff
thanks jeff,


GOM is just too expensive for my budget. i am looking for cheaper alternatives, and have heard folks here using fabrics from jo-ann, not sure what exactly.


anyone use this speaker cloth from jo-ann, looks a bit on the high end of cost.

http://www.joann.com/joann/catalog/p...2a&supercatId=


----------



## kevinzoe

Quote:

Originally Posted by *studlygoorite* 
Might you have a link to where you can order these from Toronto? I went to the RPG link and Canada is not an option. Thanks
Hi Studlygoorite (nice name by the way!):

Try calling Martin at Pilchner Schoustal in Toronto or visit their site here:
http://www.2psii.com/ 


They have a close working relationship with RPG and they may order stuff on your behalf.


----------



## studlygoorite




> Quote:
> Originally Posted by *kevinzoe* /forum/post/19801447
> 
> 
> Hi Studlygoorite (nice name by the way!):
> 
> Try calling Martin at Pilchner Schoustal in Toronto or visit their site here:
> http://www.2psii.com/
> 
> 
> They have a close working relationship with RPG and they may order stuff on your behalf.



Thanks pal.


----------



## Anthony A.




> Quote:
> Originally Posted by *kevinzoe* /forum/post/19798093
> 
> 
> Hi Anthony,
> 
> Kevin in TO here. How are you? Did you ever get the Empire Epik subs we communicated previously about?
> 
> 
> About your question, if you have only 15" between the back wall and the rear row of chairs, have you considered a diaphragmatic-type bass trap instead of the 'super chunks?' As you already are using 1" OC around the room I would hazard to guess that the RT60 is pretty low for the upper frequencies so the last thing you probably want is to reduce it further with more fiberglass super chunks. Moreover, fiberglass traps need to be thick to work really well - placement of a fiberglass trap out 15" from your back wall would work most effectively for a 226Hz wavelength (1130/226*12*0.25=15") as 15" equates to the 25% mark of the 264Hz wavelength where particle speed is maximized.
> 
> 
> I'd be inclined to consider the diaphragmatic type trap that works where pressure is maximized not particle speed so this type of trap hangs right on your back wall and is about 4" thick. Check out RPG which makes them and you can order them here in Toronto.
> 
> 
> Hope that helps somewhat. . .



hey kevin, good to hear from you. still haven't decided on adding an epik or not, but i did get another sub (svs pc12 plus). im still craving midbass punch so that is why im trying to first try out some more room tweaks and then assess the situation. the only place i can add the bass traps (at the rear of the room) that will blend in with my room is directly behind the second row of seating. since that row is about 15" away from the back wall i thought to place some traps behind it that won't be visible. i don't want to hang anything on walls, etc. can you tell me which, specifically, rpg trap you're suggesting?


thanks.


----------



## kevinzoe




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19804339
> 
> 
> hey kevin, good to hear from you. still haven't decided on adding an epik or not, but i did get another sub (svs pc12 plus). im still craving midbass punch so that is why im trying to first try out some more room tweaks and then assess the situation. the only place i can add the bass traps (at the rear of the room) that will blend in with my room is directly behind the second row of seating. since that row is about 15" away from the back wall i thought to place some traps behind it that won't be visible. i don't want to hang anything on walls, etc. can you tell me which, specifically, rpg trap you're suggesting?
> 
> 
> thanks.





You might consider this one for your floor/wall corner:
http://www.rpginc.com/products/modexcorner/index.htm 


or this one that hangs on the wall and likely could be painted black to match your wall colour so as not to be noticable:
http://www.rpginc.com/products/modexplate/index.htm 


Cheers,

Kevin


----------



## Jay5298

I have attached some pics of my room as well as a drawing of the room with dimensions, and where I plan on putting the treatments. The purple rectangles are the treatments. for the corner traps I want to build a trapezoid shaped treatment using 2 layers of O.C. 705 (4" thick total) one being the FRK, this one goes on the back correct? The side wall panels I want to use O.C 703 2" thick but I think I want to make them about 3ft wide by 5ft high. Is it okay to use a 2 x 4 panel and then cut one in half length wise and put it next to the other and then put the other piece on top to make a 3 x 5 panel and then frame it? The ceiling panels will be the same thickness but I don't know what size yet. the drawing is not really to scale that is why I have only one panel on each side of the wall towards the back of the room. I think this will be proportionally correct based on the dimensions of the room. My surround speakers are inside the columns and are dipole (Paradigm ADP-590's). Will putting side wall panels fairly close to the surrounds effect there sound too much? The panels will probably be about 2feet from the speakers based on where my rack is and then the same on the other side, and towards the back of the room. the back wall panel will be between the 2 surrounds, should this be 2" or 4" thick. My seats are about 2.5ft from the back wall. I know this is a lot of questions but any help would be greatly appreciated.

P.S next post will have the rest of the pics

Thanks,

Jay


----------



## Jay5298

More pics of room.


Thanks
 

 

HT sketch.pdf 16.1044921875k . file

 

HT sketch 2.pdf 13.89453125k . file


----------



## nathan_h




> Quote:
> Originally Posted by *Jay5298* /forum/post/0
> 
> 
> I have attached some pics of my room as well as a drawing of the room with dimensions, and where I plan on putting the treatments. The purple rectangles are the treatments. for the corner traps I want to build a trapezoid shaped treatment using 2 layers of O.C. 705 (4" thick total) one being the FRK, this one goes on the back correct?



No, the front. The idea is to not absorb too much high frequency. The FRK reflects high frequencies rather than absorbing them.



> Quote:
> The side wall panels I want to use O.C 703 2" thick but I think I want to make them about 3ft wide by 5ft high. Is it okay to use a 2 x 4 panel and then cut one in half length wise and put it next to the other and then put the other piece on top to make a 3 x 5 panel and then frame it?



This is probably too much absorption. Use the mirror method to find the first reflection points for the front speakers. They likely won't be spread up/down 5 feet. Focus the panel size on the actual reflection points. And consider increasing panel thickness an inch or two, even if it's just an air gap, to help broaden the frequency range being impacted, for a more natural effect.



> Quote:
> The ceiling panels will be the same thickness but I don't know what size yet.



Same advice: thicker is better, but less coverage as long as you hit the first reflection points is the ideal.


----------



## atledreier

There have been a few threads on the norwegian AV forums about tuned resonators as bass traps. Basically sonotubes, closed inone end, open in the other, and very little to no damping. From measurements, when tuned correctly (cut to length) they are VERY effective at killing nodes. They are also dirt cheap and very quick and easy to make.


Any thoughts on these compared to other tuned resonators?


----------



## Jay5298




> Quote:
> Originally Posted by *nathan_h* /forum/post/19806566
> 
> 
> No, the front. The idea is to not absorb too much high frequency. The FRK reflects high frequencies rather than absorbing them.
> 
> 
> 
> 
> This is probably too much absorption. Use the mirror method to find the first reflection points for the front speakers. They likely won't be spread up/down 5 feet. Focus the panel size on the actual reflection points. And consider increasing panel thickness an inch or two, even if it's just an air gap, to help broaden the frequency range being impacted, for a more natural effect.
> 
> 
> 
> 
> Same advice: thicker is better, but less coverage as long as you hit the first reflection points is the ideal.



Would 4" thick 705 unfaced be sufficient enough for the bass traps, or does the FRK backing make a difference.


I thought that 2" thickness would be enough for the mids and highs.


I want to keep the ceiling treatments as thin as possible due to fairly low ceilings.


Thanks


----------



## mtbdudex

Looking at what material I have onhand for covering my side wall/ceiling acoustic panels, I have 3 yards of this speaker 70" wide cloth from PE.

Holding it over the OC703 appears no issue, is there any thought about why NOT to use this as my acoustic panel covers?
http://www.parts-express.com/pe/show...number=260-335 











I've made 1 prototype 2' x 4' frame boxe from 1 x 4 pine, routered a 1/4" deep x 2" trench 1/2" from one side (the front), then I'll use bumpers to provide a gap to the wall side.

I'll wrap the 2" OC703 with the speaker cloth (front side only) and the pine box will be outside, nesting the 2' x 4' nicely.

This pict is wrong position of my HT, but you can see the black speaker grille will match my black speakers and go with the dark green walls fine, while I feel using the pine and staining will keep the rustic look going as well.










So, simply, using speaker cloth as shown above ok or not good for these panels?


----------



## nathan_h




> Quote:
> Originally Posted by *Jay5298* /forum/post/19809545
> 
> 
> Would 4" thick 705 unfaced be sufficient enough for the bass traps, or does the FRK backing make a difference.
> 
> 
> I thought that 2" thickness would be enough for the mids and highs.
> 
> 
> I want to keep the ceiling treatments as thin as possible due to fairly low ceilings.
> 
> 
> Thanks



In general, the goals are:

1) Control reflections, but don't go too far and lose all of them.

2) Absorb across a wide range of frequencies, typically by having thicker panels.


---


The reason for the FRK, mostly, is that you want as much bass trapping as possible, BUT you also don't want to absorb too much of the mid and high frequencies. The FRK acts to reflect the mid and high frequencies, so you don't "overdamp" your room (make it sound lifeless and inert).


So if you use the FRK, it doesn't really help with bass trapping, but it prevents problems with other frequencies.


That said, you can probably be okay without it in your scenario, if you need to not put it on/use it.


---


2 inch thickness is better than 1 inch, but not as good as 3" or 4" in most situations. In fact, getting too thin arguably causes more harm than good at some point, since it only absorbs a very limited range of frequencies and the other frequencies are inconsistently tamed. If you can do 3" or set the 2" panels off the wall with an air gap, that's better than just a 2" panel on the wall. But a 2 inch panel on the wall is better than no panel at all.


--


I understand room limitations. Most of us have those issues. So if you have to compromise on the ceiling because of that, don't sweat it. Just remember to be judicious with how much surface area you cover. Hit the key points, and don't just swath it around everywhere.


----------



## Jay5298

Thanks Nathan for the replies. So I should hit my first or early reflections first and then decide if I should put more treatments up? Do you think I should put any panels towards the back of the room between the side surround columns and the back wall? Should I put a panel between the rear surrounds to absorb the sound from the front speakers? How do you know if you need more treatments without using expensive equipment. Sorry for all the questions again.


Thanks.


----------



## nathan_h




> Quote:
> Originally Posted by *Jay5298* /forum/post/0
> 
> 
> Thanks Nathan for the replies. So I should hit my first or early reflections first and then decide if I should put more treatments up?



Yes, that and bass trapping (thick panels straddling corners) and you are probably good to go. Maybe a couple panels on the back wall if you can't fit some on the front wall.


Do a search about some free software called REW (I think) which along with some cheap hardware can help you measure things, if you are really into learning it. Or hire a pro calibrator who does audio in addition to the usual video stuff who can measure for you. If you want to dial it in more.


----------



## eugovector

REW = Room EQ Wizard


----------



## kevinzoe




> Quote:
> Originally Posted by *Jay5298* /forum/post/19810500
> 
> 
> Thanks Nathan for the replies. So I should hit my first or early reflections first and then decide if I should put more treatments up? Do you think I should put any panels towards the back of the room between the side surround columns and the back wall? Should I put a panel between the rear surrounds to absorb the sound from the front speakers? How do you know if you need more treatments without using expensive equipment. Sorry for all the questions again.
> 
> 
> Thanks.



A little education goes a long way . . . pick up a copy of Dr Floyd Toole's latest book in which you'll learn much about room acoustics, pyschoacoutic effects and why it might not be a good idea to absorb all 1st reflection points and many other pearls of wisdom. In the end, it will help you critically assess your room requirements. Before you 'waste' money and time on the wrong thickness or wrong location of a treatment, I highly recommend you study the book, and others too.


----------



## mtbdudex




> Quote:
> Originally Posted by *kevinzoe* /forum/post/19813374
> 
> 
> A little education goes a long way . . . pick up a copy of Dr Floyd Toole's latest book in which you'll learn much about room acoustics, pyschoacoutic effects and why it might not be a good idea to absorb all 1st reflection points and many other pearls of wisdom. In the end, it will help you critically assess your room requirements. Before you 'waste' money and time on the wrong thickness or wrong location of a treatment, I highly recommend you study the book, and others too.



I agree with education, this has some basic 101 stuff
http://www.crutchfield.com/learn/lea...acoustics.html 


> Quote:
> Basic tips on taming your room's reflections
> 
> 
> As we've discussed, reflected sound is necessary for music and speech to sound natural, but too much can rob your system of sound quality. The two main ways to control reflected sound are by absorbing or by diffusing (scattering) these reflections. We'll get into some more in-depth solutions on the next pages, but for now, here are a few simple tips for getting better sound in your room:
> 
> 
> 1. One of the easiest ways to improve your sound is to move your chair or sofa away from your wall and out into the middle of your room. You might also want to try positioning it closer to or farther from your speakers, and listen to see where your audio sounds best in your room.
> 
> 2. If you have a large expanse of glass in your listening room, like a picture window or French doors, try installing drapes over them to absorb reflections.
> 
> 3. Along the same lines, if you have wood or vinyl flooring, try placing an area rug to help absorb some of those harmful reflections.
> 
> 4. Bookshelves can help break up or diffuse reflections. Try placing a bookcase or two filled with odd-shaped books to the sides or in the back of your listening room to see if your sound improves.
> 
> 5. Finally, be on the lookout for "acoustics-savvy" components, such as powered subwoofers with built-in bass equalization and home theater receivers with automatic speaker calibration. They can help digitally correct for room problems when the above solutions aren't an option given your room's layout or décor.
> 
> 
> If these simple fixes don't cut it, and you still want to improve the sound in your room, then read on. We'll look at the science behind reflection, absorption, and diffusion, as well as give you some more in-depth tips on how to find and fix your room's trouble spots.





















> Quote:
> if you can see it, you can hear it. Wherever you see your speaker reflected in the mirror, that's a point of reflection that should receive absorptive, or in some cases, diffusive acoustic treatment.


----------



## nathan_h

Quote:

Originally Posted by *kevinzoe* 
A little education goes a long way . . . pick up a copy of Dr Floyd Toole's latest book in which you'll learn much about room acoustics, pyschoacoutic effects and why it might not be a good idea to absorb all 1st reflection points and many other pearls of wisdom. In the end, it will help you critically assess your room requirements. Before you 'waste' money and time on the wrong thickness or wrong location of a treatment, I highly recommend you study the book, and others too.
Toole's book is very good. He is definitely swimming against the stream in some areas (example: his heavily caveatted conclusion about unsophisticated listeners preferring "inaccurate" but pleasing side wall reflections) and is with the mainstream in other conclusions (absorption panels at first reflection points on the front wall are pleasing to both professional listeners and casual listeners).


But I don't recommend his book as a starting point.


The Crutchfield links mentioned are not bad, and The RealTraps web site primers and videos are even better.


For a first book, I'd recommend Everest's "Master Handbook of Acoustics ". It's sort of the undergraduate summary of acoustics, whereas I would call Toole the graduate seminar. For a less technical introduction than Everest, and a good bit about equipment in addition to room and system setup, Harley's "Complete Guide to High End Audio" is a good read, too.


----------



## Jay5298

Thanks guys for the responses. I will check some of these books out.


----------



## Iusteve

I hate to ask for fear of being attacked, lit on fire and kicked down the street but I am curious if someone can give me an "in a nutshell" response to a simple (for you experts, certainly not myself)question?


Are there benefits (in a dedicated)home theater to using products such as OC 703 or Rockboard (as well as fabric)on all vertical surfaces rather than just strategically placed panels in the space? And if so what are they?


I have seen many people in here that covered their entire theater (minus the ceiling) with OC 703 for example and some sort of fabric and wasnt sure if there was an added benefit to this since the cost would be much higher than just a few panels. Thanks and please dont hurt me too bad.


----------



## erkq




> Quote:
> Originally Posted by *Iusteve* /forum/post/19815399
> 
> 
> I hate to ask for fear of being attacked, lit on fire and kicked down the street but I am curious if someone can give me an "in a nutshell" response to a simple (for you experts, certainly not myself)question?
> 
> 
> Are there benefits (in a dedicated)home theater to using products such as OC 703 or Rockboard (as well as fabric)on all vertical surfaces rather than just strategically placed panels in the space? And if so what are they?
> 
> 
> I have seen many people in here that covered their entire theater (minus the ceiling) with OC 703 for example and some sort of fabric and wasnt sure if there was an added benefit to this since the cost would be much higher than just a few panels. Thanks and please dont hurt me too bad.



Jeez... no one is going to "hurt" you.










A room can become "too dead". That's what I'd be concerned with in the scenario you describe.


----------



## Iusteve




> Quote:
> Originally Posted by *erkq* /forum/post/19815427
> 
> 
> Jeez... no one is going to "hurt" you.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> A room can become "too dead". That's what I'd be concerned with in the scenario you describe.



So it is not a good idea to do this? I have seen quite a few theaters on here where people have treated all their walls with 1"-2" oc 703 and covered in fabric. This seemed like a good idea to me but you say no?


----------



## Brad Horstkotte

I think most of the rooms you're describing use rigid fiberglass on lower walls only, but cover the whole wall with fabric.


It really depends on the goals (think Dr. analogy - you don't get a prescription/treatment until after you've been diagnosed - what is the problem you're trying to treat - lower RT60? boomy bass? slap echo? poor dialog intelligibility?), and where you're starting from (room construction, carpet/pad, furniture, dimensions, speaker type, music/HT mix, etc.). The best way to diagnose is to measure, then you can come up with a plan to address whatever you find.


Caveat: I just finished installing a lot of bass traps without measuring first.







But I will measure before attempting any broadband absorption.


----------



## Iusteve




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19815667
> 
> 
> I think most of the rooms you're describing use rigid fiberglass on lower walls only, but cover the whole wall with fabric.
> 
> 
> It really depends on the goals (think Dr. analogy - you don't get a prescription/treatment until after you've been diagnosed - what is the problem you're trying to treat - lower RT60? boomy bass? slap echo? poor dialog intelligibility?), and where you're starting from (room construction, carpet/pad, furniture, dimensions, speaker type, music/HT mix, etc.). The best way to diagnose is to measure, then you can come up with a plan to address whatever you find.
> 
> 
> Caveat: I just finished installing a lot of bass traps without measuring first.
> 
> 
> 
> 
> 
> 
> 
> But I will measure before attempting any broadband absorption.



How would one go about rigid fiberglass on the bottom and fabric on the top and keep them the same depth from the wall?


As for measuring I am not enough of an audiophile to even understand all the little details that go into knowing what all this stuff means. I am in the construction phase and not even to the drywall stage but was trying to plan out my build so I could be ready.


----------



## mtbdudex




> Quote:
> Originally Posted by *Iusteve* /forum/post/19815768
> 
> 
> How would one go about rigid fiberglass on the bottom and fabric on the top and keep them the same depth from the wall?
> 
> 
> As for measuring I am not enough of an audiophile to even understand all the little details that go into knowing what all this stuff means. I am in the construction phase and not even to the drywall stage but was trying to plan out my build so I could be ready.



People use non-acoustic absorbing stuff on the top (above the mid rail mldg usually) to keep the same "look" but not over absorb....look at some of the infamous build threads here....it's all in the design pkg done by the experts here


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Iusteve* /forum/post/19815768
> 
> 
> How would one go about rigid fiberglass on the bottom and fabric on the top and keep them the same depth from the wall?



Some put batting or something else less aborptive at the top behind the fabric, others I imagine just leave it empty and rely on the stretch of the fabric across the furring / panel framing to keep it even up front. The fabric goes over the insulation at the bottom, and the nothing / something light on top.



> Quote:
> Originally Posted by *Iusteve* /forum/post/19815768
> 
> 
> As for measuring I am not enough of an audiophile to even understand all the little details that go into knowing what all this stuff means.



There's definitely a learning curve (I'm not over it yet), but if you can get to the point of figuring out how to get REW set up and working, and do a measurement with the software, others here and elsewhere (htshack, home of REW) can help interpret what the graphs mean and what you can do to address any issues that it highlights.


Let your ears help too - are there any audio problems that you're hoping to address?


Or, there are people who do this for a living who can help.


----------



## studlygoorite




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19815667
> 
> 
> I think most of the rooms you're describing use rigid fiberglass on lower walls only, but cover the whole wall with fabric.
> 
> 
> It really depends on the goals (think Dr. analogy - you don't get a prescription/treatment until after you've been diagnosed - what is the problem you're trying to treat - lower RT60? boomy bass? slap echo? poor dialog intelligibility?), and where you're starting from (room construction, carpet/pad, furniture, dimensions, speaker type, music/HT mix, etc.). The best way to diagnose is to measure, then you can come up with a plan to address whatever you find.
> 
> 
> Caveat: I *just finished installing a lot of bass traps without measuring first.*
> 
> 
> 
> 
> 
> 
> 
> But I will measure before attempting any broadband absorption.



I just installed 2" thick panels at my 1st and secondary reflection points with just two 12" X 5' X2" thick panels on the back wall because I sit close to it. I find that I have new sound that makes my room sound much larger than the 16'X21' that it is and love it. I have 2 large 15" Paradigm Servo subs and am lacking in bass. Without measuring my plan is as follows, I am going to buy some 6lb density Knauf and place two 4"X2'X4' at the back wall where it meets the ceiling and two more at the front wall where it meets the ceiling, then I am going to cut a peice of the Knauf and place a piece behind each regular panel that I already have installed. Now it has been suggested that my lack of bass is due to the lack of decent bass traps and the positioning of my subs so without measuring if I did this plan does anyone think I can ruin my sound or does my plan sound like it will work? I only ask because my dealer told me that my Anthem D2v Receiver with ARC would do a better job at calibrating than getting a guy in to calibrate, that means I would have no measurements to go off of and am just going with what I read on here and other places and suggestions from people like the informative people in here.










John


----------



## Brad Horstkotte

Have you tried doing a "sub crawl" to see what effect different sub locations might have?


When you say "lack of bass", the thing I wonder is whether you have a lack of bass across the subs' range, or peaks and dips, such that you've got a dip that gives you that lack of bass impression.


Also, are you using a receiver with bass management (Audyssey, MCACC, etc.), and how is your crossover set?


----------



## Roger Dressler




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19816150
> 
> 
> I just installed 2" thick panels at my 1st and secondary reflection points



Second reflection points? Isn't that like a whole lot of points? Are there any bare wall areas left?



> Quote:
> I have 2 large 15" Paradigm Servo subs and am lacking in bass.



Where are they located?


----------



## pepar




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/19817039
> 
> 
> Second reflection points? Isn't that like a whole lot of points? Are there any bare wall areas left?



If you covered the Firsts, there are no SECONDS, are there?


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19817142
> 
> 
> If you covered the Firsts, there are no SECONDS, are there?



Anyplace you could see the speakers reflected in TWO mirrors in a row.


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/19817142
> 
> 
> If you covered the Firsts, there are no SECONDS, are there?



were talking acoustics not the birds and bees, right....


----------



## pepar

hehe, dude


Roger's underlying point is right on; that is likely too much absorption.


----------



## studlygoorite

lol, what I meant was I covered the 1st reflection points and then on the left wall where I can see the right front speaker and visa versa. Also going to do the ceiling, I have not done the crawl method yet for my subs as I thought I have tried just about every spot available but will try it this weekend as suggested earlier. Right now the best place I have found for the subs to get a nice punch for loud music is at arms length on either side of me facing toward the front of the room. I sit 4' from the back of the room in the middle, I have tried them at the front corners pointing towards the back, at the back corners pointing toward the front, one third from the front on the side walls pointing towards the back, in the middle of the side walls pointing toward the middle, this one gave me the best graph with Anthem's ARC (Anthem Room Correction) but lacked the punch. When I play a test tone of 80hz or 100hz I can hardly hear it sitting in my chair but is is quite loud behind my chair up by the ceiling, hoping good bass traps will remedy my problem.


PS: I am only worried about getting the right sound from my rocker reclyner.


John


----------



## Brad Horstkotte

Do you get the same lack of bass at the seating position with just one of the subs playing? Are both subs the same distance away from the seating position, and the phase set the same? It might be good to take one of the subs out of the equation for testing purposes. With two subs, in addition to position relative to the seating position, and room interactions, you bring in interaction between the two subs as an additional variable - potential for constructive (peaks) and destructive (dips) interference.

http://www.windows2universe.org/eart...nado/beat.html 


(caveat: I'm not a pro, just trying to offer some food for thought)



> Quote:
> Originally Posted by *studlygoorite* /forum/post/19817775
> 
> 
> what I meant was I covered the 1st reflection points and then on the left wall where I can see the right front speaker and visa versa.



Oh, that's still a first reflection then. A secondary reflection would be like it bounces off one surface (such as back wall), then another (say ceiling), then hits your ear.


----------



## studlygoorite




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19817924
> 
> 
> Do you get the same lack of bass at the seating position with just one of the subs playing? Are both subs the same distance away from the seating position, and the phase set the same? It might be good to take one of the subs out of the equation for testing purposes. With two subs, in addition to position relative to the seating position, and room interactions, you bring in interaction between the two subs as an additional variable - potential for constructive (peaks) and destructive (dips) interference.
> 
> http://www.windows2universe.org/eart...nado/beat.html
> 
> 
> (caveat: I'm not a pro, just trying to offer some food for thought)
> 
> 
> 
> 
> Oh, that's still a first reflection then. A secondary reflection would be like it bounces off one surface (such as back wall), then another (say ceiling), then hits your ear.



I have tried it with one sub that is why I purchased the second thinking that adding another would help. They are both the same distance from my seat and phase is set the same. I'll still try the crawl test this weekend and see what comes from it, but I can't go wrong getting more bass traps correct, I have read that you cannot have too many?


John


----------



## pepar

Or too many subs, John.


----------



## smokarz

recently completed my movie/media room downstairs and am anxious to build some acoustic panels.


picked up the phone and called the local SPI to get some OC 703s, and to my surprise they NO LONGER CARRY Owen Corning products.


the rep suggested something call CertainTeed Commercial boards, said it's the same as OC 703.


anyone has any experience with this product?


thanks


----------



## pepar

Just match it up here - http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Jay5298

Yesterday I actually used the mirror test to find out my reflection points on the side walls. My first row of seats are about 14.5ft from the screen, second set of seats about 19ft or so back. My question is should I build a larger panel say 3 to 4ft wide to cover all the seats or just use two 2 X 4 panels and put them next to each other. If I do build a larger panel is it okay to put two pieces of OC 703 next to each other and then wrap it with GOM. I know I asked this before but did not get an answer to this question. One other question about the front wall. Most of the wall is taken up by the screen. The bass traps will pretty much cover the sides. Should I cover the bottom portion of the wall with OC 703 and if so what thickness? My previous posts have the pictures of the room (#6834,6835)


Thanks


----------



## nathan_h




> Quote:
> Originally Posted by *Jay5298* /forum/post/19822332
> 
> 
> Yesterday I actually used the mirror test to find out my reflection points on the side walls. My first row of seats are about 14.5ft from the screen, second set of seats about 19ft or so back. My question is should I build a larger panel say 3 to 4ft wide to cover all the seats or just use two 2 X 4 panels and put them next to each other. If I do build a larger panel is it okay to put two pieces of OC 703 next to each other and then wrap it with GOM.



Custom sizing the wall space covered by the panels to match your room layout is one of the nice luxuries of building your own panels. Sounds like a very workable solution.




> Quote:
> I know I asked this before but did not get an answer to this question. One other question about the front wall. Most of the wall is taken up by the screen. The bass traps will pretty much cover the sides. Should I cover the bottom portion of the wall with OC 703 and if so what thickness? My previous posts have the pictures of the room (#6834,6835)
> 
> 
> Thanks



Remember, those panels on the sides aren't really bass traps. Bass traps would be even thicker, and positioned differently in the room.


I placed 8 inch thick panels along the floor/wall juncture under my screen, wrapped in black fabric, with a nice impact on bass response.


If you are going to put some panels on the front wall, and they are not at reflection points, I recommend making them as thick as possible (for bass trapping) and placing them at wall/floor/ceiling/wall junctures (optimum placement for bass trapping). You don't need to use GOM for these, since even a non-porous fabric will allow the bass frequencies through, and that is what you are want to capture/impact when not treating a first reflection point.


----------



## Jay5298

Remember, those panels on the sides aren't really bass traps. Bass traps would be even thicker, and positioned differently in the room.


Nathan, I meant the bass traps on either side of the screen in the corners would cover most of the front wall except for below the screen. So putting a 2 X 4 panel next to another panel and then framing it is okay?


----------



## nathan_h

Sure.


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/19822060
> 
> 
> Just match it up here - http://www.bobgolds.com/AbsorptionCoefficients.htm



thanks, looking at that chart i see a least a few products from each brand that are very similiar to the OC 703 3pfc.


wondering what specific products others are using as alternatives for OC 703 from the JM and Knauf brands.


----------



## smokarz

JM CB 300 price.....


a local supplier quoted me $99 for 9 sheets of 2" 2'x4'. isn't this EXPENSIVE?


----------



## smokarz

placed an order for 2 bundles of OC 703 2" 2x4 for $81 or roughly $0.80 per sf.


i am thrilled!


----------



## smokarz

hey guys, what is the exact size for OC 703 2x4? is it really 2x4?


i plan to build frames this weekend, so when the OC 703s are delivered, i can just plug it in and be done. thanks


----------



## Brad Horstkotte

Yup 2'x4' give or take say an eighth of an inch - unless squished in transit / storage.


----------



## smokarz

thanks, going to head over to the local home depot to get materials for framing.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19816150
> 
> 
> Now it has been suggested that my lack of bass is due to the lack of decent bass traps and the positioning of my subs so without measuring if I did this plan does anyone think I can ruin my sound or does my plan sound like it will work?



It is more likely the result of the sub positioning or seating, or it could be the volume of the room and the capabilities of the subwoofer. It could be a number of things really...this is where the HUMAN comes in contrary to your dealer. Oi.



> Quote:
> I only ask because my dealer told me that my Anthem D2v Receiver with ARC would do a better job at calibrating than getting a guy in to calibrate



Oh brother!







Who is your dealer??!! Not true...not true at all. ARC, like Audyssey, is a tool...nothing more. It will absolutely not take the place of proper positioning, seating arrangement, treatment, AND someone who knows what they are doing when it comes to calibration. Audyssey, to their credit, will be forth-right enough to say as much. All of the "automajik" buttons are blind and "stoopid" when it comes to these elements...no if's, and's or but's about it. They also will not tell you if you have a blown tweeter or other problems with your speakers, and I frequently catch, at least Audyssey, claiming that the polarity of a speaker is incorrect after I checked every driver individually for just such a problem. The general consumer, without specialized equipment may think otherwise and start flipping wires to correct a ghost problem. Bottom line is, the automajik stuff is often better than nothing, but it will not, repeat not, take the place of a proper calibration with a human being. Best wishes!


----------



## studlygoorite

Quote:

Originally Posted by *SierraMikeBravo* 
It is more likely the result of the sub positioning or seating, or it could be the volume of the room and the capabilities of the subwoofer. It could be a number of things really...this is where the HUMAN comes in contrary to your dealer. Oi.




Oh brother!







Who is your dealer??!! Not true...not true at all. ARC, like Audyssey, is a tool...nothing more. It will absolutely not take the place of proper positioning, seating arrangement, treatment, AND someone who knows what they are doing when it comes to calibration. Audyssey, to their credit, will be forth-right enough to say as much. All of the "automajik" buttons are blind and "stoopid" when it comes to these elements...no if's, and's or but's about it. They also will not tell you if you have a blown tweeter or other problems with your speakers, and I frequently catch, at least Audyssey, claiming that the polarity of a speaker is incorrect after I checked every driver individually for just such a problem. The general consumer, without specialized equipment may think otherwise and start flipping wires to correct a ghost problem. Bottom line is, the automajik stuff is often better than nothing, but it will not, repeat not, take the place of a proper calibration with a human being. Best wishes!








Well I have done the crawl test and found that the middle of the side walls sounded the best. I placed both subs there, one on either side wall pointing towards the middle of the room and ran ARC(Anthem Room Correction). I no longer have a kick with the bass, not sure if getting good bass traps will help this, the subs put out 1500 watts of continuous power each(Paradigm Servo 15"X2) and my ceiling is only 7' high. Maybe it's the concrete floor under the carpet, not sure but it also sounds like most of my bass is still in the upper corners by the ceiling. Maybe try raising the subs off the floor?

I thought it funny that my dealer said that ARC would do a better job than a calibrator, but maybe he meant better than his calibrator. Looks like I may have to find a guy that may be able to help in my area.


John


----------



## SierraMikeBravo

Quote:

Originally Posted by *studlygoorite* 
Well I have done the crawl test and found that the middle of the side walls sounded the best. I placed both subs there, one on either side wall pointing towards the middle of the room and ran ARC(Anthem Room Correction). I no longer have a kick with the bass, not sure if getting good bass traps will help this, the subs put out 1500 watts of continuous power each(Paradigm Servo 15"X2) and my ceiling is only 7' high. Maybe it's the concrete floor under the carpet, not sure but it also sounds like most of my bass is still in the upper corners by the ceiling. Maybe try raising the subs off the floor?

I thought it funny that my dealer said that ARC would do a better job than a calibrator, but maybe he meant better than his calibrator. Looks like I may have to find a guy that may be able to help in my area.


John
Hi John,


Well, Dennis and I will be in the area first week of February.


----------



## Jay5298

I found OC 703 from a local supplier in Colorado, but no one stocks 705. I can find it online but shipping is expensive. I was going to use the 705 for the bass traps straddling the corners 4" thick. How much of a difference would there be using 4" thick 703 instead. I have seen the numbers, but need some real world advice.


Thanks


----------



## nathan_h

Not a lot of difference, imo.


----------



## scoobygt68

So I received installed some acoustic treatments in my room last night. I installed 4 bass traps up front straddling the corners 4" thick stacked from floor to ceiling. I attached the bottom trap (the 1 that sits on the floor) to the wall so it is perfectly secure. The top trap sits on top of the bottom one and go up to about 1" below the ceiling... but I was unsure as to how to attach it to wall so they are just sitting on top of the bottom ones. I also put an acoustic panel at the left and right 1st reflection points which I located using the mirror method, and then one behind my center channel between my screen and the floor.


I dont currently have any subs in the room as they are on order, but I do have 7 full range speakers in my set up. I only listened to some music for about 20 mins but I did listen to the same material before I installed the traps/panels so I could try to make some comparisons. First off I noticed a change in the higher end. The vocals seemed slightly more sharp with less echo-like characteristic, especially when I really cranked it up. The lower end was a bit puzzling. I was listening to the Eagles Farewell Tour DVD - One of These Nights, and I noticed a drum sound that I have never heard before, and I've listened to that dvd a lot. Idk if the sound was a good or bad sound... it was different than any drum sound I've heard on this track. It seemed to last for a good 1.5 seconds. It didnt sound like an echo or boomy sound, it just seemed to last a bit longer than the other bass/drum sounds on the track.


----------



## smokarz

hey guys, how do you hang your panels on the wall?


just gathering ideas, thanks!


----------



## Jay5298

I'm probably over thinking this but I have attached a picture of one of my side walls. I drew a rectangle area in black where my first reflections are for every seat in my theater. The panel will have to be 4' high by about 6.5' wide in order to cover every seat, and that doesn't even include all the reflections from the opposite speaker for the back row of seats. The ceiling will have to be similar in size for all the seats. I don't think I have ever seen a panel that is that big in a home theater. So what do you guys do to cover all the seats. I have seen several panels placed next to each other, or spaced a little bit apart, but then are you really getting all the reflections. This is driving me insane.


----------



## pepar

I built a 4' x 8' panel in-place on my front ceiling. And 4' x 4' panels on front left and right front points. The rear wall panel is 2' x 8'.


Check the link in my sig.


----------



## Jay5298




> Quote:
> Originally Posted by *pepar* /forum/post/19882521
> 
> 
> I built a 4' x 8' panel in-place on my front ceiling. And 4' x 4' panels on front left and right front points. The rear wall panel is 2' x 8'.
> 
> 
> Check the link in my sig.



Do you think this could make the room too dead having such a large space covered with panels or a large panel?


----------



## SierraMikeBravo

It may not make the room dead, but it sure will kill the envelpoment depending on what you use. Have you measured the response of those speakers yet?


----------



## Jay5298




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19882786
> 
> 
> It may not make the room dead, but it sure will kill the envelpoment depending on what you use. Have you measured the response of those speakers yet?



I'm sorry but this is getting more confusing by the minute. I don't have a laptop computer so measuring my system is going to be difficult. I thought that putting panels at the reflection points was a good thing. How will this kill the envelopment?


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Jay5298* /forum/post/19882805
> 
> 
> I guess I don't know what you mean by response.



Download a free RTA software such as REW or True RTA (lowest version) and use a microphone to measure the nearfield response of your speakers from 20Hz-20kHz and plot that. Then you'll also need to do several more in various positions off the center axis and overlay all the responses. The plots will help to determine which treatment you need or should use. You do this for every speaker. Is it work, yep, but this is the only good method to determining the treatment you should be using. Hope this helps.


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/19882805
> 
> 
> I'm sorry but this is getting more confusing by the minute. I don't have a laptop computer so measuring my system is going to be difficult. I thought that putting panels at the reflection points was a good thing. How will this kill the envelopment?



It is very easy to overdampen a small room. And Mike is recommending learning about your speaker's response off-axis/dispersion to know if any of the panels being discussed are necessary. For example, my fronts are very controlled in vertical dispersion so it is likely that my ceiling panel is overkill. I am about to swap the fiberglass in it for dispersion.


At least that's my take on what he is saying, but then I am not an acoustician .... nor did I stay at a Holiday Inn Express last night.


Jeff


----------



## Jay5298

Well I either need to do one of two things. Hire an expert to do this work ,or spend some more time trying to measure things in my theater before spending too much money on things I don't need. I have ordered the insulation for my bass traps already, but I think putting in those first should be safe.


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/19883345
> 
> 
> Well I either need to do one of two things. Hire an expert to do this work ,or spend some more time trying to measure things in my theater before spending too much money on things I don't need. I have ordered the insulation for my bass traps already, but I think putting in those first should be safe.



I think you are.


----------



## SierraMikeBravo

I should also specify, this type of test is primarily for the first reflections. Vertical dispersion anomalies associated with the ceiling reflection can often be seen in the farfield repsonse at the listening position. In the nearfield, we are only interested as to what the speaker is actually outputting without room effects...although it is not completely without it, but near enough that we hope to get a decent plot.


If that seems a bit complex and you begin to wonder if it is worth your time, a pro might be of use to you, and they can lay out your room for a relatively small sum. Best wishes!


----------



## video_bit_bucket




> Quote:
> Originally Posted by *studlygoorite* /forum/post/19845788
> 
> 
> Well I have done the crawl test and found that the middle of the side walls sounded the best. I placed both subs there, one on either side wall pointing towards the middle of the room and ran ARC(Anthem Room Correction). I no longer have a kick with the bass, not sure if getting good bass traps will help this, the subs put out 1500 watts of continuous power each(Paradigm Servo 15"X2) and my ceiling is only 7' high. Maybe it's the concrete floor under the carpet, not sure but it also sounds like most of my bass is still in the upper corners by the ceiling. Maybe try raising the subs off the floor?
> 
> I thought it funny that my dealer said that ARC would do a better job than a calibrator, but maybe he meant better than his calibrator. Looks like I may have to find a guy that may be able to help in my area.
> 
> 
> John



Someone correct me but the advantage of two subs is that you can put the second sub in a null left by the first one. In doing so you fill the null with output from the second. Doing the crawl with the first sub does not recommend the second sub for the same position on the opposite wall.


I have the Servo v2 as well. Something about those subs, presumably the servo function, can really kill the output if it is coupling with the room badly. Just to be aware. I used the single speaker test in ARC to locate my single sub. Saved a lot of time compared to a traditional crawl and made a big difference in room response.


----------



## Dennis Erskine

That is not the point of two subs. In the typical room, you'll find the "best" location for your sub will be out in the middle of the floor some where. Clearly, you don't want that big box in such a location. When two subs are installed, they "couple" and behave as though there is a single sub located approximately 1/2 between the two.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19884409
> 
> 
> That is not the point of two subs. In the typical room, you'll find the "best" location for your sub will be out in the middle of the floor some where. Clearly, you don't want that big box in such a location. When two subs are installed, they "couple" and behave as though there is a single sub located approximately 1/2 between the two.



I thought that the two (or four) mid-wall placements were to smooth out room modes by "driving" the room .. and therefore the room modes .. from opposite sides, and that mutual coupling occurred only when the subs are within 1/2 wavelength (~ 2m for an 85Hz upper frequency) of each other?


Jeff


----------



## Jay5298




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/19883837
> 
> 
> I should also specify, this type of test is primarily for the first reflections. Vertical dispersion anomalies associated with the ceiling reflection can often be seen in the farfield repsonse at the listening position. In the nearfield, we are only interested as to what the speaker is actually outputting without room effects...although it is not completely without it, but near enough that we hope to get a decent plot.
> 
> 
> If that seems a bit complex and you begin to wonder if it is worth your time, a pro might be of use to you, and they can lay out your room for a relatively small sum. Best wishes!



Well, do you know of any good companies in Denver, Colorado that I could call.

Thanks


----------



## pepar

Quote:

Originally Posted by *Jay5298* 
Well, do you know of any good companies in Denver, Colorado that I could call.

Thanks
I'll throw this out there as well; the online sellers of acoustical treatments will provide design as part of their customer service if you are purchasing from them. GIK, RealTraps, etc.


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/19885899
> 
> 
> I'll throw this out there as well; the online sellers of acoustical treatments will provide design as part of their customer service if you are purchasing from them. GIK, RealTraps, etc.



Right, they won't come to your place and measure the room response, but if your room is not too strange, and you can give them accurate physical dimensions, and photographs, they have enough experience to get you a long ways towards success.


My room was treated based on such "at a distance" advice, and when I finally had a little cash to get a pro in to measure the room, he said it was essentially "perfect" -- or within the realm of taste, rather than accuracy.


My room is an almost perfect box (eg, approx 12.5x7.5x20 or something, I don't have the numbers with me) and is sealed (one solid core insulated "exterior" door with weather stripping) and is drywalled with framing making for a room within a room, and r13 insulation all around -- so saying that, plus showing photos, let the vendor get very specific about treatment type, size, locations.


And best of all, I was able to say "my budget is $500 now, so tell me what to do with that, and then tell me what to add when I have another $500 later, and then if I have another $500 beyond that" and he was happy to do that -- even though I was honest and said I wasn't committing to buying round two from him, etc. (Turns out I bought round one from him, and did half of the rest as DIY stuff.)


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Jay5298* /forum/post/19885705
> 
> 
> Well, do you know of any good companies in Denver, Colorado that I could call.
> 
> Thanks



Hi Jay,


There are plenty of good pros right here on the site! Dennis Erskine, Bryan Pape, and Terry Montlick just to name a few. They can provide you the necessary treatment plans if that is what you desire, as well as speaker placement etc. AVS also offers this service http://shop.avscience.com/Pro-Theater-Layout_p_44.html# . Hope this helped!


----------



## Dennis Erskine

You can contact Mike Orlowski at Alpine Vista.
www.alpinevista.com 


orlowski at alpinevista dot com


He is based in Breckenridge and does work in Denver.


----------



## Tireman1

Is there a time when foil out is good on the front/screen wall? How about the rear wall? 705FRK


Thanks


----------



## Emig5m

I'm nearing completion of a 16x13 room with an 8' vaulted ceiling that my system will be going in and I've decided I'm probably just going to order panels from ATS. How many panels should I order to start me off? Room will be wall-to-wall carpet and furnished like a average living room. I was thinking 2 2x4' panels per wall (8 total) - is this about right or too much and also thickness (2" vs 4" thick)? Thanks.


----------



## Jay5298

Dennis, I will give this company a call and see what they can do for me. Unfortunately I don't want to spend a lot of money. I know you only get out what you put in, but I just want to tweak the room a little bit to see if it will sound better. I sent my room pics and dimensions to a company called Ready acoustics but they have not got back to me yet. From everything that I have read putting bass traps in the corners and treating the first reflections seems to be the best thing I can do for my theater. I know you can over do it but doing these minimum treatments seems pretty universal in almost any small theater room. I want to see if bass traps will smooth the bass out around my whole room. I have 2 subs and it sounds pretty good to me already, I just want to see what the traps can do. I would also like to treat the reflections to help with speech intelligibility and to create a better front sound stage. The center channel always seems to sound a little muffled compared to the other speakers a far as voice recognition goes. Someone suggested just treating the reflections for the primary seats. 90% of the time it's just my wife and I watching a movie. If I start there and treat just those spots and then see what it sounds like I may not need to continue putting more treatments up for the rest of the seats, and if I do no harm will be done. I understand that measuing the room should be the first step, and then deciding which treatments to use should be the next step. Like Nathan said he did his room based on what people had shown him according to his room dimensions and pictures and possibly equipment. I would like to do this approach as well I just don't want to spend more money on the consulting than the cost of the treatments themselves. I love this hobby, actually obsession, but sometimes it can be very overwhelming.


----------



## Dennis Erskine

Mike has the equipment to measure your room and tell you exactly what you need so you don't waste any money guessing about it.


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/19889589
> 
> 
> I would also like to treat the reflections to help with speech intelligibility and to create a better front sound stage. The center channel always seems to sound a little muffled compared to the other speakers a far as voice recognition goes.



What is your center channel speaker, where is it located and where is it aimed?


Jeff


----------



## smokarz




> Quote:
> Originally Posted by *smokarz* /forum/post/19880624
> 
> 
> hey guys, how do you hang your panels on the wall?
> 
> 
> just gathering ideas, thanks!



anyone?


my frames are 2'x4'. made of pinewood 1"x3", 2" OC 703, and wrapped with fabric from jo-ann. thanks


----------



## Jay5298




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19890615
> 
> 
> Mike has the equipment to measure your room and tell you exactly what you need so you don't waste any money guessing about it.



Thanks Dennis, I will give Mike a call.


----------



## Jay5298




> Quote:
> Originally Posted by *pepar* /forum/post/19891033
> 
> 
> What is your center channel speaker, where is it located and where is it aimed?
> 
> 
> Jeff



My center is a Paradigm CC-590 (V4) located directly below the screen slightly angled up. My pictures of the room are in posts #6834, 6835.


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/19891096
> 
> 
> My center is a Paradigm CC-590 (V4) located directly below the screen slightly angled up. My pictures of the room are in posts #6834, 6835.



I would aim it directly at the ears of the listener in the center seat. What is the floorcovering? Are your walls and ceiling hard?


----------



## nathan_h




> Quote:
> Originally Posted by *smokarz* /forum/post/0
> 
> 
> 
> anyone?
> 
> 
> my frames are 2'x4'. made of pinewood 1"x3", 2" OC 703, and wrapped with fabric from jo-ann. thanks



Hang it like a picture in a frame.


----------



## Jay5298




> Quote:
> Originally Posted by *pepar* /forum/post/19891360
> 
> 
> I would aim it directly at the ears of the listener in the center seat. What is the floorcovering? Are your walls and ceiling hard?



Wall to wall carpet with 1/2" foam carpet pad, walls and ceiling are double drywall. When I say "muffled" I guess I mean the speech needs to be more precise, or more intelligible.


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/19891467
> 
> 
> Wall to wall carpet with 1/2" foam carpet pad, walls and ceiling are double drywall.



Make sure it is aimed so that the main listener's ears are as close to being on axis as possible.


You mentioned "muffled." Is that what you mean? If so, check the drivers especially the tweeters; there might be something blown. If you just mean that dialog is difficult to understand, i.e. lacks intelligibility, then it might be that some absorbers would help.


Something you could try to troubleshoot this further before spending any dosh would be to tell your receiver/processor that you have no center channel and make it go phantom for the center. If that makes difference in the sound of the dialog, it might be a further clue.


----------



## Jay5298




> Quote:
> Originally Posted by *pepar* /forum/post/19891502
> 
> 
> Make sure it is aimed so that the main listener's ears are as close to being on axis as possible.
> 
> 
> You mentioned "muffled." Is that what you mean? If so, check the drivers especially the tweeters; there might be something blown. If you just mean that dialog is difficult to understand, i.e. lacks intelligibility, then it might be that some absorbers would help.
> 
> 
> Something you could try to troubleshoot this further before spending any dosh would be to tell your receiver/processor that you have no center channel and make it go phantom for the center. If that makes difference in the sound of the dialog, it might be a further clue.



Thanks, I will give those suggestions a try.


----------



## smokarz




> Quote:
> Originally Posted by *nathan_h* /forum/post/19891433
> 
> 
> Hang it like a picture in a frame.



with a nail into the drywall? there's got to be some better ways. this is 10x bigger and heavier than a typical picture.


----------



## erwinfrombelgium

Folks,


Fascinating stuff here!


Could you please assess my effort so far.

I am designing and building a new house. The multipurpose room with HT is situated on ground level in a big wood-framed house and sits on top of a concrete basement. Also lots of triple glass from ceiling to floor on the left, the rear wall even 100% glass. All glass has heavy black curtains.


For insulation, I am aiming for a properly decoupled box-in-box with double layer of drywall with heavy foil sandwiched or Green Glue. The space inbetween the joists will be partly filled with fiberglass.

The floor will be seamless black PU if you agree.

The grey zone on the floorplan is a ceiling with soundtraps, thickness 4" and cavity also 4".

The front wall has 2 tower subwoofers, tuned to 13 Hz. The rest of the frontwall has 12" thick soundtraps.


I noticed that the basstraps here often described work from 60 Hz upwards. What about the 15 to 60 Hz? Don't these go right through all that drywall instead of being reflected?

Attachment 199396 

Attachment 199395 

 

Ronse2010B_HTacoustic.pdf 264.2666015625k . file

 

Ronse2010B_HTplan6.pdf 415.0625k . file


----------



## Brad Horstkotte

I would research the STC of the window construction first - to validate that any investment in beefing up walls wouldn't be defeated by all that glass.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/19893168
> 
> 
> with a nail into the drywall? there's got to be some better ways. this is 10x bigger and heavier than a typical picture.



Got any studs in your drywall?










Jeff


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19893551
> 
> 
> Got any studs in your drywall?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



Or use drywall anchor bolts.


----------



## studlygoorite




> Quote:
> Originally Posted by *Jay5298* /forum/post/19892225
> 
> 
> Thanks, I will give those suggestions a try.



I have been messing with my subs for quite some time now and had possibly the same senario as you, my center speaker sounded a little canned. I realized that I had not set the phase on my subs after the last time I moved them and when I did set it my canned sound cleared up.


John


----------



## erwinfrombelgium




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19893333
> 
> 
> I would research the STC of the window construction first - to validate that any investment in beefing up walls wouldn't be defeated by all that glass.



STC stands for?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *erwinfrombelgium* /forum/post/19893832
> 
> 
> STC stands for?



Sound Transmission Class, a measure of how easily sound travels through a structure / material.

http://www.stcratings.com/ 
http://www.stcratings.com/assemblies.html 
http://www.calglassbending.com/stctable.htm (maybe the maker of your glass panes would have specific information on them if you can track that down??)


My thought (I'm no expert) is that you'd only want to invest in soundproofing measures for the walls in the room if the windows wouldn't end up being a significantly weaker link, otherwise those measures might go for naught.


Basically my response is a placeholder until Ted White or Dennis Erskine comes along to tell you the real answer.


----------



## smokarz




> Quote:
> Originally Posted by *erkq* /forum/post/19893587
> 
> 
> Or use drywall anchor bolts.





> Quote:
> Originally Posted by *pepar* /forum/post/19893551
> 
> 
> Got any studs in your drywall?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



yes, but i am concern about getting the panel leveled with just a nail or screw?


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/19894113
> 
> 
> yes, but i am concern about getting the panel leveled with just a nail or screw?



I don't think the member who suggested hanging it like a picture really meant one hook and a wire stretched from side to side. At least I hope not.










Get a studfinder and hit all the studs that pass behind the panel. With 16" centers, you should be able to anchor to two with a 48" panel, but even with a 24" panel, you'll hit one.


Three pages in from here is what I'm talking about.


----------



## Dennis Erskine

STC or Sound Transmission Class is a single number which has been derived to provide an indication of a material's or assembly's resistance to sound passing through the material. Measurements (in a lab) are made at frequencies from 125Hz to 4000kHz. Those values are plotted and then fit against a curve to derive the single value. Due to the nature of the curved fitting, assemblies with the same STC value can have radically different performance at any given frequency.


It is not a good value to use for Audio playback spaces ... note the measured range: 125Hz to 4000kHz .... heck your sub doesn't start doing anything worthwhile until 80Hz and what about from 4kHz to 20kHz. You do not want to look at the STC number, you want to look at the TL (transmission loss) values.


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/19894113
> 
> 
> yes, but i am concern about getting the panel leveled with just a nail or screw?



Not "a" nail or screw... use 2 and level the screws relative to each other. You can shim between them and the panel frame if fine-tuning is necessary.


----------



## smokarz




> Quote:
> Originally Posted by *erkq* /forum/post/19895153
> 
> 
> Not "a" nail or screw... use 2 and level the screws relative to each other. You can shim between them and the panel frame if fine-tuning is necessary.



i see, so two screws for each panel in the studs 16" apart. i guess the challenge now is to level the screws. i see commercials for a "laser leveler"? does that thing work?


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/19895379
> 
> 
> i see, so two screws for each panel in the studs 16" apart. i guess the challenge now is to level the screws. i see commercials for a "laser leveler"? does that thing work?



You could do that. But I'm more "old school" and just use a regular level. Put the first screw in at the height you want and then use a level to mark the height of the other. A stud-finder is handy too if you don't want to use anchor bolts.


Myself, I don't worry about studs. The panels aren't heavy enough to need them. I just drill a hole wherever I want with a proper sized drill for the wood screw I would use if I hit a stud. If I hit a stud, great, I use the wood screw. If I hit a void then I use a drywall anchor. There's a chance you could hit a stud a "glancing blow" with the drill but I've not had that happen, or I just didn't know that happened. Honestly, with the weight of a panel I don't think it will make much difference.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *smokarz* /forum/post/19895379
> 
> 
> i see, so two screws for each panel in the studs 16" apart. i guess the challenge now is to level the screws. i see commercials for a "laser leveler"? does that thing work?



They work - but keep in mind that your floor/ceiling may not be level, so level relative to one or the other.


----------



## erwinfrombelgium




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19893890
> 
> 
> Sound Transmission Class, a measure of how easily sound travels through a structure / material.
> 
> http://www.stcratings.com/
> http://www.stcratings.com/assemblies.html
> http://www.calglassbending.com/stctable.htm (maybe the maker of your glass panes would have specific information on them if you can track that down??)
> 
> 
> My thought (I'm no expert) is that you'd only want to invest in soundproofing measures for the walls in the room if the windows wouldn't end up being a significantly weaker link, otherwise those measures might go for naught.
> 
> 
> Basically my response is a placeholder until Ted White or Dennis Erskine comes along to tell you the real answer.



Thanks for that. I never heard of such a thing in Europe. All the glass is triple pane, not laminated except for the glass in the door. What counts is that it will be properly spaced and decoupled from the frames anyway, since this a "passive house". If you prevent heat transfer, then you also lower the sound transfer IMO. But I have to attach those frames to the building ofcourse.


I hope to do as good a job upfront with integrated sound insulation and absorption. I can put some tube traps in front of the windows afterwards.


What I really want to know also how the lowest frequencies behave (15-50 Hz) in relation to the materials such as drywall and double drywall with Green Glue inbetween? I know "normal" frequencies are reflected, but LFE content?


----------



## erkq




> Quote:
> Originally Posted by *erwinfrombelgium* /forum/post/19899223
> 
> 
> If you prevent heat transfer, then you also lower the sound transfer IMO.



It seems this would be the case, but it is not. Heat is EMF and a very different animal from the molecular vibration of sound.


For example you could have a single pane of glass coated with a modern, highly effective IR reflector. This IR reflection would not effect sound in any way. The sound would only see a normal pane of glass while IR reflection is so effective that standing in the sun's reflection feels like actually standing in the sun!


It really depends on the type of heat transfer you are insulating for. Thermal transfer: yes, often it helps with sound insulation. Radiation transfer: no... there's no relation to sound.


----------



## erwinfrombelgium




> Quote:
> Originally Posted by *erkq* /forum/post/19899319
> 
> 
> It seems this would be the case, but it is not. Heat is EMF and a very different animal from the molecular vibration of sound.
> 
> 
> For example you could have a single pane of glass coated with a modern, highly effective IR reflector. This IR reflection would not effect sound in any way. The sound would only see a normal pane of glass while IR reflection is so effective that standing in the sun's reflection feels like actually standing in the sun!
> 
> 
> It really depends on the type of heat transfer you are insulating for. Thermal transfer: yes, often it helps with sound insulation. Radiation transfer: no... there's no relation to sound.



Well, I hope we don't start semantics, but indeed, I wasn't thinking about reflection of tainted or special glass, I was just referring to the fact that you do not "throw" your glas into the frame without proper spacers and sealants, so this will be a good side-effect to improve sound insulation. Inside a passive house, you simply do not hear traffic noise in the same magnitude as in standard houses, if you hear it at all. Airgaps are avoided, foam is used, the frames are made out of sandwich material, certainly not aluminum, etc... Ok?


----------



## erkq




> Quote:
> Originally Posted by *erwinfrombelgium* /forum/post/19901403
> 
> 
> Well, I hope we don't start semantics, but indeed, I wasn't thinking about reflection of tainted or special glass, I was just referring to the fact that you do not "throw" your glas into the frame without proper spacers and sealants, so this will be a good side-effect to improve sound insulation. Inside a passive house, you simply do not hear traffic noise in the same magnitude as in standard houses, if you hear it at all. Airgaps are avoided, foam is used, the frames are made out of sandwich material, certainly not aluminum, etc... Ok?



Gotcha! Sorry to be so pedantic.


----------



## Tireman1

Opinion before I glue panels

I am already pretty deep in with a lot of information from the AVS forum. Sometimes good information to an untrained person can get them in trouble. That untrained person is me.

The room has a soffit built out 24 inches from the wall, this includes a 4 inch light tray, and drops down 10 inches. It is stuffed with fiber glass and finished off with 705FRK foil down except the first five feet which is foil up. The ceiling will be a star ceiling constructed of 1" rigid fiberglass,and GOM 701 (Numinus). My current plans are to cover the entire screen wall foil out facing the room and entire back wall foil against the wall. Both screen wall corners to have floor to ceiling base traps using the 705FRK. Side walls floor to ceiling first five feet foil in then sixty inches high from the floor up foil out. Room is 19.5 wide 24 long ceiling 9' Do you see any glaring errors?


Thanks


----------



## nathan_h

This appears to be a decent plan.


My reaction is: Sounds like overkill on the ceiling in terms of coverage, and too thin to impact the sound evenly. And for the back wall, it sounds like too much coverage, again.


The bass traps are a great idea, but you may want some of the front wall to not have foil facing, and you may want to flip the back wall to have some foil facing


----------



## Dennis Erskine

Actually, double and triple pane windows are very poor at sound isolation. It is not the multiple panes ... it is the thickness of the glass that would count.


----------



## price3

Has anyone ever used stone as a diffusing medium? I have some left over from a fireplace and could use it in a strip on my rear wall if it would be beneficial. This is the only pic I could find:











Also, if making soffit bass traps, with 1/2" sheetrock covering loose insulation should I cut vents in or leave it sealed?


----------



## erwinfrombelgium




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19902823
> 
> 
> Actually, double and triple pane windows are very poor at sound isolation. It is not the multiple panes ... it is the thickness of the glass that would count.



Yet, I have been inside passive houses quite close to a busy road. As soon as you close the front door behind you, it's very silent! I know that proper soundproofing glass uses several panes of various thickness to adress multiple frequencies, but it's the airtightness IMO that's the big factor.


I plan to decouple the roomsurface as much as possible from the structure of the house. It's hard to find info about how the sub-bass reacts to a system with double drywall and Green glue or heavy foil sandwiched in them. All the info I found has graphics from 60 Hz upwards.


The floor will also be a double layer of cement-based dryfloor (2 * 9 mm) sitting on top of 2 layers of hardfoam insulation, finished with 3 mm of PU seamless floorsystem. Would it be advisable here also to use Green Glue or a damping foil between both cement panels?


----------



## nathan_h




> Quote:
> Originally Posted by *price3* /forum/post/0
> 
> 
> Has anyone ever used stone as a diffusing medium? I have some left over from a fireplace and could use it in a strip on my rear wall if it would be beneficial. This is the only pic I could find:
> 
> 
> Also, if making soffit bass traps, with 1/2" sheetrock covering loose insulation should I cut vents in or leave it sealed?



Stone would be better than a flat wall, but to be predictably effective would need to have bigger peaks and valleys than in that photo. That looks like a visual flourish but not an effective sound treatment.


You want something much thinner than half inch Sheetrock covering a bass trap. Examples: fabric, foil, paper. If you look at some of the build threads here you'll see some creative solutions. Example, one whole side is left unsheetrocked and is covered with fabric.


----------



## Ethan Winer




> Quote:
> Originally Posted by *price3* /forum/post/19903099
> 
> 
> Has anyone ever used stone as a diffusing medium?



That won't work very well for various reasons, mostly because there's not enough depth. More here:

All About Diffusion 



> Quote:
> If making soffit bass traps, with 1/2" sheetrock covering loose insulation should I cut vents in or leave it sealed?



A soffit as you describe will not work as a bass trap because sheet rock is too dense to let bass waves pass through to the insulation inside. You need to make a wood frame, then stretch fabric (or staple cardboard) to the frame.


--Ethan


----------



## Dennis Erskine




> Quote:
> I plan to decouple the roomsurface as much as possible from the structure of the house. It's hard to find info about how the sub-bass reacts to a system with double drywall and Green glue or heavy foil sandwiched in them. All the info I found has graphics from 60 Hz upwards.



One of the reasons for 60Hz and above, is that many labs get to their flanking limit pretty quickly. You can find data on DD and Green Glue at www.soundproofingcompany.com . I don't know what frequencies you mean by the phrase "sub bass". You will not gain anything with "heavy foil" between the layers of gypsum board unless you consider 1/4" plate steel to be "heavy foil" and all the plate steel would bring is mass. BTW, Green Glue is technically a CLD material and does provide absorption of vibratory energy while pure mass is reflective.


One of the problems here is you have not defined specifically the problem you want to solve. 15Hz is not audible and the solution to frequencies in that range is defined by the energy behind those frequencies.


None-the-less, regardless of how much you think you know about the windows, it is somewhat counterproductive to be going full bore on the walls/ceiling/floor when the window(s) will be your weakest link.


----------



## price3

How can risers made of thick plywood be used as bass traps if the waves will not pass through 1/2" sheetrock?


----------



## mtbdudex




> Quote:
> Originally Posted by *price3* /forum/post/19904895
> 
> 
> How can risers made of thick plywood be used as bass traps if the waves will not pass through 1/2" sheetrock?



You put HVAC vents in the plywood....
http://www.avsforum.com/avs-vb/showt...php?p=15441346


----------



## Ethan Winer




> Quote:
> Originally Posted by *price3* /forum/post/19904895
> 
> 
> How can risers made of thick plywood be used as bass traps if the waves will not pass through 1/2" sheetrock?



I believe that type of riser is designed with slots as a tuned Helmholtz absorber. But most domestic size rooms benefit most from _broadband_ bass trapping.


--Ethan


----------



## Brad Horstkotte

@Tireman1 - I'm not sure why you'd want to ever use FRK insulation with the foil against the wall - wouldn't you accomplish the same thing by using unfaced ? FRK was about twice the price of unfaced when I shopped for it.


----------



## mtbdudex




> Quote:
> Originally Posted by *smokarz* /forum/post/19891051
> 
> 
> anyone?
> 
> my frames are 2'x4'. made of pinewood 1"x3", 2" OC 703, and wrapped with fabric from jo-ann. thanks





> Quote:
> Originally Posted by *pepar* /forum/post/19894391
> 
> 
> I don't think the member who suggested hanging it like a picture really meant one hook and a wire stretched from side to side. At least I hope not.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Get a studfinder and hit all the studs that pass behind the panel. With 16" centers, you should be able to anchor to two with a 48" panel, but even with a 24" panel, you'll hit one.
> 
> Three pages in from here is what I'm talking about.





> Quote:
> Originally Posted by *smokarz* /forum/post/19895379
> 
> 
> i see, so two screws for each panel in the studs 16" apart. i guess the challenge now is to level the screws. i see commercials for a "laser leveler"? does that thing work?



I just got done making and hanging these 2' x 4' panels ( 2" 703 covered), will post more details/picts when I get home.


----------



## erwinfrombelgium




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19904252
> 
> 
> One of the reasons for 60Hz and above, is that many labs get to their flanking limit pretty quickly. You can find data on DD and Green Glue at www.soundproofingcompany.com . I don't know what frequencies you mean by the phrase "sub bass". You will not gain anything with "heavy foil" between the layers of gypsum board unless you consider 1/4" plate steel to be "heavy foil" and all the plate steel would bring is mass. BTW, Green Glue is technically a CLD material and does provide absorption of vibratory energy while pure mass is reflective.
> 
> 
> One of the problems here is you have not defined specifically the problem you want to solve. 15Hz is not audible and the solution to frequencies in that range is defined by the energy behind those frequencies.
> 
> 
> None-the-less, regardless of how much you think you know about the windows, it is somewhat counterproductive to be going full bore on the walls/ceiling/floor when the window(s) will be your weakest link.



Well, I think sub bass is the bass from the sub? Between 15 and 80 Hz? The subs I am building are tuned to 13 Hz (-3dB). I was told movies have LFE content from 15 Hz. If I don't hear it, I will certainly feel that energy? Doesn't gipsum absorb more low frequencies than, say, concrete or marble?


I am still in the fase of the structure (waiting for dry weather for the EPDM on the flat roof). I want to avoid as many problems upfront as I can. I am prepared to use laminated glass to improve things if you think this is the weakest link.


I started to read that book "Home Recording Studio: build it like the pro's". I"ll get back afterwards...


----------



## Neurorad

I've done some searching, and I can't find any mention of L-R 'height' channels on AVS. Anyone using them? What are everyone's feelings on them? Putting the wiring in place for a possible future implementation would cost $10. Will it ever be popular, do you think?


----------



## Tireman1




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19905368
> 
> 
> @Tireman1 - I'm not sure why you'd want to ever use FRK insulation with the foil against the wall - wouldn't you accomplish the same thing by using unfaced ? FRK was about twice the price of unfaced when I shopped for it.



I got a deal on FRK @ $64 per case


----------



## nathan_h




> Quote:
> Originally Posted by *price3* /forum/post/19904895
> 
> 
> How can risers made of thick plywood be used as bass traps if the waves will not pass through 1/2" sheetrock?



I think the responses above probably summarize it but to be obnoxious: The answer is they can't, without big openings covered only by something like paper, fabric or foil (or a grate, etc).


----------



## Anthony A.

by adding bass traps, will that help the nulls in any way or simply reduce the peaks so that you get a flatter FR throughout, though at the expense of reduced output (which i guess could be increased by channel trim)?


----------



## pepar




> Quote:
> Originally Posted by *Neurorad* /forum/post/19906619
> 
> 
> I've done some searching, and I can't find any mention of L-R 'height' channels on AVS. Anyone using them? What are everyone's feelings on them? Putting the wiring in place for a possible future implementation would cost $10. Will it ever be popular, do you think?



Thanks for dropping in to the Acoustical Treatments Master Thread







... search here http://www.avsforum.com/avs-vb/showt...5421&page=1186


----------



## pepar




> Quote:
> Originally Posted by *Anthony A.* /forum/post/19907600
> 
> 
> by adding bass traps, will that help the nulls in any way or simply reduce the peaks so that you get a flatter FR throughout, though at the expense of reduced output (which i guess could be increased by channel trim)?



Reducing the reflected energy lessens the constructive and destructive interference. As Johnny Carson used to say "for those of you in Rio Linda, that peaks and nulls."


OK, he never said that, but I'm sure he would have if you had asked him the question.


----------



## bonedoc2be




> Quote:
> Originally Posted by *mtbdudex* /forum/post/0
> 
> 
> 
> You put HVAC vents in the plywood....
> http://www.avsforum.com/avs-vb/showt...php?p=15441346



Yup. That is exactly what Dennis Erskine did with my riser. There are openings in the corner and via the columns.


----------



## nathan_h

Quote:

Originally Posted by *Anthony A.*
by adding bass traps, will that help the nulls in any way or simply reduce the peaks so that you get a flatter FR throughout, though at the expense of reduced output (which i guess could be increased by channel trim)?
Nulls get less deep and peaks get less tall. To me, it sounds louder overall with trapping, but maybe that's just cause it's balanced and I can hear more of what's in the recording.


----------



## pepar

When you reduce the ringing, everything sounds clearer.


----------



## mtbdudex

Hanging 101 for DIY framed 2' x 4' acoustic panels:

(I just got done hanging this 6th panel tonight)


I used alum "z" from ats acoustics, http://www.atsacoustics.com/item--ac...are--IK12.html 

















Measure twice, use blue tape for visual markers, locate top holder, mine was a 1 1/2" thick piece so the panel would have 2" air gap.

Hold with hand, drill into drywall with 3" deck screw, mini-level assures level.

Holders were pre-made, pre-drilled, and painted wall color prior.-------------Locate bottom holder, drill into drywall with 3" deck screw.


















Remove, use drilled holes to locate the 50lb plastic dywall anchors------Re-attach top/bottom holders, using 3" deck screw.

















If measurements done correctly slight tweaks to get level----this shows 2" air gap

















btw, not to get OT acoustics, but has anybody else noticed the 50lb drywall anchors seemed "whimpy" lately?

I bought the ones on RH 1 week ago - , the ones on LH are 3-4 years old.

(they RH ones looked like the old 35lb ones to me in store, but I read the label and bought them)

Look at the size diff, logic says a larger bite in drywall = larger holding power.

So, which one is really the 50lb anchor?

Old one was clearly marked "made in USA", new one said nothing on cover, however flipping it over...."made in China"....


----------



## erkq

Quote:

Originally Posted by *mtbdudex* 
btw, not to get OT acoustics, but has anybody else noticed the 50lb drywall anchors seemed "whimpy" lately?
I don't think it's OT. Methods of mounting our panels are important.

I love that style of anchor. I use it exclusively for everything. I think there are 2 different sizes for different sized screws. I've used both sizes. I'm out of the bigger one now and need to get some more. It'll be interesting if I can find them. No problem last time.


----------



## smbsocal

Our theater room has an 8' high drop ceiling that uses 5/8" rigid fiberglass ceiling tiles (Cinetiles).


Below the ceiling I do not have room to place corner bass traps due to doors in the way. Above the drop ceiling I have 20" between the drop ceiling and the joists.


Would I have an effective bass trap if I filled the 20" gap between the ceiling tiles and the joists with regular fiberglass insulation? The 5/8" Cinetiles use a thin layer of sprayed on black paint so I believe bass should be able to pass through them. So if I include the insulation in the joists that would give me 5/8" of rigid fiberglass (ceiling tile) and ~32" of normal fiberglass insulation in the corners.


Thanks


----------



## nathan_h




> Quote:
> Originally Posted by *mtbdudex* /forum/post/19908230
> 
> 
> Hanging 101 for DIY framed 2' x 4' acoustic panels:
> 
> (I just got done hanging this 6th panel tonight)



Thanks for posting your hanging method. This is sure to help others, by showing anther great option for how to do it.


And I should add: nice room, and judicious use of side wall panels. Refreshing to see a room in which it's maxed out but nor overdone.


----------



## Dennis Erskine




> Quote:
> Doesn't gipsum absorb more low frequencies than, say, concrete or marble?



Not exactly. It is frequency dependent and assembly dependent. Gypsum could seem to "absorb" more bass; but, what it is really doing is allowing more bass to pass through the material than, say, concrete. However, gypsum is always an assembly. It's behavior will include many factors (including mounting horizontally or vertically), stud spacing, stud flex, and others. Concrete doesn't have to be an assembly ... it can be free standing.


When sound energy conflicts with an object, one or all of three things can happen: (1) sound is reflected; (2) sound energy is absorbed; and/or (3) sound energy passes through. Transmission loss metrics will tell you what is passing through. Coefficients of Absorption will tell you want is being absorbed and the balance is reflected.


----------



## mtbdudex




> Quote:
> Originally Posted by *nathan_h* /forum/post/19909842
> 
> 
> Thanks for posting your hanging method. This is sure to help others, by showing anther great option for how to do it.
> 
> 
> And I should add: nice room, and judicious use of side wall panels. Refreshing to see a room in which it's maxed out but nor overdone.



Thx, I used the software "first order reflections" initially, planned what to do, and then bought for $7 a 1' x 4' mirror from Target to confirm before actually placing them.

The software was spot on in prediction of where to put panels.


Now, for my ceiling I realize my center lights are exactly where I need absorbers for center channel first order reflections, doing a google on DIY acoustic cloud saw this on gearslutz.com, a guy there put rope lights around the frame perimiter.....that's an option not sure if it will be gauwy looking or what.


My plan is 4" thick OC703 (using 2 2" unfaced panels) with a spaced 4" gap to the ceiling, I have room above the top frame of the screen to do that.

I was going to do the w/o frames at all, just hanging via these from ats acoustics










For now, I'll un-screw the center lights and see how bad that affects the lighting in the room, we really only use those on low dim for sporting events or when the kids are playing games, for HT usage no lights at all.
http://www.gearslutz.com/board/bass-...ing-cloud.html


----------



## cuzed2




> Quote:
> Originally Posted by *smbsocal* /forum/post/19909158
> 
> 
> Our theater room has an 8' high drop ceiling that uses 5/8" rigid fiberglass ceiling tiles (Cinetiles).
> 
> 
> Below the ceiling I do not have room to place corner bass traps due to doors in the way. Above the drop ceiling I have 20" between the drop ceiling and the joists.
> 
> 
> Would I have an effective bass trap if I filled the 20" gap between the ceiling tiles and the joists with regular fiberglass insulation? The 5/8" Cinetiles use a thin layer of sprayed on black paint so I believe bass should be able to pass through them. So if I include the insulation in the joists that would give me 5/8" of rigid fiberglass (ceiling tile) and ~32" of normal fiberglass insulation in the corners.
> 
> 
> Thanks



I have an open floorplan. YThe opening adjacent to my "theater" room opens to a 13'x21' billiard room with a dropped ceiling. I have about 20" from the top of the tiles to the floor above. I have a 24" width of the pink stuff stuffed all away around the perimeter of this room above the ceiling tiles. For bass trapping not ideal, BUT it was well worth the modest cost of the pink stuff. Yes I would do it.


----------



## Neurorad




> Quote:
> Originally Posted by *pepar* /forum/post/19907649
> 
> 
> Thanks for dropping in to the Acoustical Treatments Master Thread
> 
> 
> 
> 
> 
> 
> 
> ... search here http://www.avsforum.com/avs-vb/showt...5421&page=1186



Hey thanks, pepar. That Audyssey thread was really helpful. Is that your attempt at humor? Fix bad room acoustics with EQ?


Admittedly I should have been more clear.


Ethan, Dennis, and any other experienced HT designers - do you make any specific recs for L-R height channels, for layout designs? Would there be any change to the acoustical treatments with the use of height channels?


----------



## pepar




> Quote:
> Originally Posted by *Neurorad* /forum/post/19911746
> 
> 
> Hey thanks, pepar. That Audyssey thread was really helpful. Is that your attempt at humor? Fix bad room acoustics with EQ?
> 
> 
> Admittedly I should have been more clear.
> 
> 
> Ethan, Dennis, and any other experienced HT designers - do you make any specific recs for L-R height channels, for layout designs? Would there be any change to the acoustical treatments with the use of height channels?


*Recommendation for the location of height channels are made by the companies who make the technology that derives the channels ... Dolby or Audyssey.* (The recommendations will be in degrees and not feet.) Ethan and Dennis might have recommendations for acoustical treatments if there are height channels.


I linked the Audyssey thread for that reason.


----------



## smbsocal




> Quote:
> Originally Posted by *cuzed2* /forum/post/19911580
> 
> 
> I have an open floorplan. YThe opening adjacent to my "theater" room opens to a 13'x21' billiard room with a dropped ceiling. I have about 20" from the top of the tiles to the floor above. I have a 24" width of the pink stuff stuffed all away around the perimeter of this room above the ceiling tiles. For bass trapping not ideal, BUT it was well worth the modest cost of the pink stuff. Yes I would do it.



Great, thanks for the info. It is pretty much my only option so I was hoping it would work, even if not optimal.


----------



## erwinfrombelgium




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19910051
> 
> 
> Not exactly. It is frequency dependent and assembly dependent. Gypsum could seem to "absorb" more bass; but, what it is really doing is allowing more bass to pass through the material than, say, concrete. However, gypsum is always an assembly. It's behavior will include many factors (including mounting horizontally or vertically), stud spacing, stud flex, and others. Concrete doesn't have to be an assembly ... it can be free standing.
> 
> 
> When sound energy conflicts with an object, one or all of three things can happen: (1) sound is reflected; (2) sound energy is absorbed; and/or (3) sound energy passes through. Transmission loss metrics will tell you what is passing through. Coefficients of Absorption will tell you want is being absorbed and the balance is reflected.



Yeah, that makes sense.

Thanks.


----------



## HMenke

Has anyone tried the acoustical panels from Frabricmate Systems?

http://www.fabricmatestore.com/c-110...al-panels.aspx 


Looks like a great selection of sizes, fabrics, and colors. I would like to hear from anyone who has tried them.


----------



## DIYHomeTheater

I came across two papers that demystified the whole process of audio calibration and achieving excellent sound more than the nearly 7,000 posts on this thread did. Both are by Floyd E. Toole:


" The Acoustical Design of Home Theaters "


" Loudspeakers and Rooms - Working Together "


Toole took the trouble to explain in layman terms to walk through the entire calibration process. Dennis Erskine's post #4171 was also very useful.


Thank you, gents.


----------



## erwinfrombelgium

I made some adjustments in the detailing


*Made the design more symmetrical

*Used a double framed wall on the right adjacent to my son's bedroom. All the walls use the same design. Double drywall with Green Glue in between, two 75 mm frames filled with fiberglass. One frame is loadbearing, hence in wood, second is placed on a decoupled floor and made from metalstuds. In general, I will make sure the box-in-box principle is carried as far as reasonable. Especially the ceiling.

*The door construction is adjusted to this design.

*Broadband Absorption is used for 80% of the ceiling and also at the rear (glass) wall and the front wall. Elements are 4", 8" or 12" thickness with a similar distance to the wall or glass.

*Added bottle racks in the kitchen, AKA sound dispersers... Played with the depth: four different fills: 0", 3", 6" and 9". With some bottles in it, this should be efficient...

Here:
Attachment 199940 

*Floor is a double layer "dryfloor", a cement based panel, with Green Glue inbetween. Finished with a black layer of PU (3 mm), looks kinda like vinyl, but nicer to walk on barefoot.

*I did some reading on soundproofed glass. I could use a laminated panel and other thicknesses. Due to the size of the glass (100" * 100") panels, I need 6/15/6/15/6 mm glass (6mm = 1/4"), even 8/15/8/15/8 for the big one on the left. To improve soundproofing, I could ask to make 4+5(lam)/15/6/15/8 or something like that. But if I read the specs correct, the main benefit is in the middle frequencies. Meaning that the highs are reflected (ofcourse) and the low frequencies stil go right through! the idea is to prevent sound-energy from making connection to the main construction as much as possible. I think the extreme specs of the special frames are good and we must make sure to fill all the gaps with foam and sealings, try not to use solid connections.


Plan #8
Attachment 199932 

 

Ronse2010B_HTplan8.pdf 498.1220703125k . file

 

Ronse2010B_HTAanzichtKeuken.pdf 309.2705078125k . file


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *doublewing11* /forum/post/19138436
> 
> 
> Thanks for the input SMB..........
> 
> 
> Your input several months ago literally stopped me in my tracks...........since then, your suggestions have taken me in another direction.
> 
> 
> I'm an independently minded person and really wanted to get involved with putting this theater together. I'm close to understanding what I want/need in terms of budget and aesthetics.....and will summon the help of a designer to put it together once I'm 100% sure of my goals and path of implementation.
> 
> 
> Yeah, I know............room first, but can't help myself in regard to audio equipment. Would love to audition the Procella brand, but with that said, am heavily leaning toward either Aerial (LR5/SR3) or Triad (Gold Monitors/Gold surrounds) for implementation.
> 
> 
> One step at a time...........................



Any suggestions for AFFORDABLE speakers that have a flat off-axis and on-axis response for an HT? Thanks


----------



## Dennis Erskine

Well first ... no speaker will have flat off axis response. Just physics working against you. What you are looking for is as you get more off axis, the shape of the response curved matches the on axis response .... as you get more and more off axis, you'll get a roll off in the higher frequencies. I posted a couple of examples of "good" and "bad" several months ago .... can't find it now.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19921305
> 
> 
> Well first ... no speaker will have flat off axis response. Just physics working against you. What you are looking for is as you get more off axis, the shape of the response curved matches the on axis response .... as you get more and more off axis, you'll get a roll off in the higher frequencies. I posted a couple of examples of "good" and "bad" several months ago .... can't find it now.



Dennis:


I believe that you recommended the following as having _excellent_ off-axis response:


Procella, Aerial (LR5/SR3) or Triad (Gold Monitors/Gold surrounds) - all VERY EXPENSIVE


You mentioned 'B&W' as _not_ having good off-axis (sigh! I have the B&W 805 Matrix with matching center channels that I was hoping to use). See response curves below:









_B&W Matrix 805, vertical response family at 45", normalized to response on tweeter axis, from back to front: differences in response 15 degrees-7.75 degrees above axis, reference response, differences in response 7.5 degrees-22.5 degrees below axis._









_B&W Matrix 805, lateral response family at 45", normalized to response on tweeter axis, from back to front: differences in response 90 degrees-5 degrees off-axis, reference response, differences in response 5 degrees-90 degrees off-axis._


So, the above monitor is not good? I think that the response varies nearly the same at all angles which is a desirable property.


The search for affordable monitors that have a good off-axis response continues...


----------



## Dennis Erskine

There isn't much change as the off axis angle increases; but, the direct on axis and the off axis is radically different.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> There isn't much change as the off axis angle increases; but, the direct on axis and the off axis is radically different.



So, are these good enough for LCR or does their performance leaves much to be desired? Not sure how to interpret your opinion on these

Thanks


----------



## pepar

Most people have theaters that they greatly enjoy that are not as good as - or as expensive as - one of Dennis' theaters.


----------



## JapanDave




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/19919457
> 
> 
> I came across two papers that demystified the whole process of audio calibration and achieving excellent sound more than the nearly 7,000 posts on this thread did. Both are by Floyd E. Toole:
> 
> 
> " The Acoustical Design of Home Theaters "
> 
> 
> " Loudspeakers and Rooms - Working Together "
> 
> 
> Toole took the trouble to explain in layman terms to walk through the entire calibration process. Dennis Erskine's post #4171 was also very useful.
> 
> 
> Thank you, gents.



There are numerous posts with links to Floyd E. Toole's papers and also quite a bit of discussion on his ideas in this thread, the information is here. Just remember that Floyd E. Toole's research is just one of many people in this industry. I think it would be best to gather all the information on as many different experts and take it from there.


I personally know for a fact that I could not build a theater that sounds as good as what Dennis builds, no matter how much research I do. Practical experience combined with theoretical knowledge can't be beat. But that is just my opinion.


----------



## Dennis Erskine

Found 'em. Here's the examples of good vs not so good off axis response. You might notice the "dip" or "notch" that appears in the bad example. That is what the B&W plots above exhibit. (These examples did not use B&W speakers.)


----------



## pepar




> Quote:
> Originally Posted by *JapanDave* /forum/post/19923552
> 
> 
> 
> I personally know for a fact that I could not build a theater that sounds as good as what Dennis builds, no matter how much research I do. Practical experience combined with theoretical knowledge can't be beat. But that is just my opinion.




Of course I don't disagree with anything there, but my point is that there are plenty of speakers that people can be happy with that do not meet Dennis' criteria. Expressed another way and extended, the practically-near-perfect is the enemy of the good, and people all of a sudden let doubt creep in and poison their experience.


I heard the THX/Procella demo at CEDIA and it was stunning .. one of the best I've ever heard. It was slightly surpassed IMO by the Wisdom Audio demo. Procella speakers are, I believe, are $10k - $20k each. The Wisdoms are $20k - $30k each. I didn't price the associated electronics or, in the case of the Procella room, design and treatments. People with 10k-20k-30k _*TOTAL*_ for a theater system shouldn't be thrown off course so far that they never regain their confidence in being able to spend a modest amount of money and have something worth while.


Anyone can spend a $100-$200 and get a great bottle of wine. The challenge is to spend $20 and get a near-great bottle of wine.


Jeff


----------



## Dennis Erskine

I don't disagree with Jeff here. The real point of knowing the quality of the off axis response is that data will tell you whether you need absorption at early reflection points or diffusion. You want to absorb bad off axis response and diffuse the good stuff. As a point of history, this whole live-end/dead-end business all started due to a popular speaker (at the time in the 80's) which had awful off axis response and that was the fix. Those who didn't know better then adopted that practice as a general rule rather than as a specific approach to a specific speaker.


There are a fair number of not so expensive speakers which exhibit excellent sound quality ... Atlantic Technology, Triad are among them.


BTW ... send me the name/vintage of that $20 bottle of fine wine.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19924182
> 
> 
> 
> There are a fair number of not so expensive speakers which exhibit excellent sound quality ... Atlantic Technology, Triad are among them.



Thanks, now that news we can use!



> Quote:
> BTW ... send me the name/vintage of that $20 bottle of fine wine.



Ahh, you're calling me out on that one, eh? The trick is to buy the right wine and lay it down for a 3-10 years. I don't think there is an analogy for speakers.










Jeff


----------



## JapanDave




> Quote:
> Originally Posted by *pepar* /forum/post/19924139
> 
> 
> Of course I don't disagree with anything there, but my point is that there are plenty of speakers that people can be happy with that do not meet Dennis' criteria. Expressed another way and extended, the practically-near-perfect is the enemy of the good, and people all of a sudden let doubt creep in and poison their experience.
> 
> 
> I heard the THX/Procella demo at CEDIA and it was stunning .. one of the best I've ever heard. It was slightly surpassed IMO by the Wisdom Audio demo. Procella speakers are, I believe, are $10k - $20k each. The Wisdoms are $20k - $30k each. I didn't price the associated electronics or, in the case of the Procella room, design and treatments. People with 10k-20k-30k _*TOTAL*_ for a theater system shouldn't be thrown off course so far that they never regain their confidence in being able to spend a modest amount of money and have something worth while.
> 
> 
> Anyone can spend a $100-$200 and get a great bottle of wine. The challenge is to spend $20 and get a near-great bottle of wine.
> 
> 
> Jeff



I don't disagree at all. I was hoping that the poster "DIYHomeTheater" did not think that all he problems were answered in those papers. That is only the begining of what needs to be taken into consideration and the more I dig the deeper I get, alone with more confusion. At some stage of the game, trail and error may have to be used. But, with the advise of an expert who understands this stuff and has the experience under their belt, that trail and error can be eliminated to a certain degree.


We both are sharing the same opinion about your wine analogy, obviously b/c not everyone is made of money.


----------



## mtbdudex




> Quote:
> Originally Posted by *JapanDave* /forum/post/19923552
> 
> 
> There are numerous posts with links to Floyd E. Toole's papers and also quite a bit of discussion on his ideas in this thread, the information is here. Just remember that Floyd E. Toole's research is just one of many people in this industry. I think it would be best to gather all the information on as many different experts and take it from there.
> 
> 
> I personally know for a fact that I could not build a theater that sounds as good as what Dennis builds, no matter how much research I do. Practical experience combined with theoretical knowledge can't be beat. But that is just my opinion.



+1, if I had a "do-over", I'd still be DIY but pay DE's company (or some of the other good ones) for the HT plans.

Same reason you don't hire someone directly outta college and give them the "big assignment" immediately, they know the theory (hopefully) but need to garner experience and knowledge/know-how.

I'd consider that the single best investment for anyones HT.


----------



## pepar




> Quote:
> Originally Posted by *JapanDave* /forum/post/19924296
> 
> 
> I don't disagree at all. I was hoping that the poster "DIYHomeTheater" did not think that all he problems were answered in those papers. That is only the begining of what needs to be taken into consideration and the more I dig the deeper I get, alone with more confusion. At some stage of the game, trail and error may have to be used. But, with the advise of an expert who understands this stuff and has the experience under their belt, that trail and error can be eliminated to a certain degree.





> Quote:
> Originally Posted by *mtbdudex* /forum/post/19924314
> 
> 
> +1, if I had a "do-over", I'd still be DIY but pay DE's company (or some of the other good ones) for the HT plans.
> 
> Same reason you don't hire someone directly outta college and give them the "big assignment" immediately, they know the theory (hopefully) but need to garner experience and knowledge/know-how.
> 
> I'd consider that the single best investment for anyones HT.



This is a good point for me to step up and admit my errors as a DIY'er. The egg on my face is somewhat excused by my "design" being rooted in 20+ year old thinking .. my house/room is 20 years old.


I read the F. Alton Everest book and some other stuff at the time, and went with an LEDE room. Initially, it was for stereo with Infinity 2002 speakers. But when surround hit, the room treatments stayed. On top of that, I built and installed absorbers at the first reflection points. If I would have known then what I know now, I would have looked at my THX Ultra M&K S-150-based speaker system and foregone the front ceiling absorber and installed diffusion instead of absorbers front left and right. I now find myself scheming to swap the 703 in both for diffusors.


Paying a pro six or so years ago when my present design took shape would have saved me some time and expense. And, admittedly, I am still experimenting .. taking concepts that I pick up here and there and trying to translate them to my application. OK, I am stubborn, too.


Jumping into the wayback machine to do it all over again .. today .. I would enlist the services of a pro to do at least a basic treatment design. Along with the pros on this thread, AVS offers such a design service.


Jeff


----------



## Norman Varney

Just to be clear, a homogeneous panel can incorporate some low frequency absorption properties when looking at Transmission Loss. There are three regions that characterize how a panel reacts to sound energy across a range of frequencies:


Region 1) a. Stiffness. The overall stiffness of a barrier influences its ability to radiate energy in the low frequency range, just below its low frequency resonance region.


Region 1) b. Resonance. As we continue to move up the spectrum, we find many low frequency resonances that are driven not only by stiffness, but are also driven by the mass of the overall structure. Wave velocity within the various materials, the size and thickness of the partition, use (or lack) of structural connections, cavity air space, etc., contribute to low frequency resonances (flexing).


Region 2) Mass Controlled. Based on the overall weight that a partition plays to control TL.


Region 3) Coincidence. When the bending sound waves form within the surface sheets of the wall, floor or ceiling partition and coincide with the incident sound wave striking the panel, a resonance forms called "coincidence". The location and magnitude of this dip is primarily dependent on the density of the material, its modulus of elasticity, and its thickness.


----------



## nathan_h

Quote:

Originally Posted by *DIYHomeTheater*
B&W Matrix 805, lateral response family at 45", normalized to response on tweeter axis, from back to front: differences in response 90 degrees-5 degrees off-axis, reference response, differences in response 5 degrees-90 degrees off-axis.


So, the above monitor is not good? I think that the response varies nearly the same at all angles which is a desirable property.


The search for affordable monitors that have a good off-axis response continues...
Actually as Denis' response implies, as long as no one is sitting precisely on axis, the whole off axis area is pretty decently consistent.


This is pretty easy to set up for every speaker other than the center channel.


----------



## Bunga99

Sorry if I posted this in the wrong thread...


I've been thinking about doing some room treatments and noticed some SonoSuede HD 1212 and 1218 from Auralex at my local Guitar Center.


I understand they won't much or anything in terms of bass treatment but my question is how well will they work for cutting down high hz reflections? They seem to be price relatively cheap.


Does anyone have any experience with these they would like to share or it is best to save up go the GIK or Real Trap route? I tried doing some research on them online but cant find any reviews.


Any input is greatly appreciated.


Thx,

Claude


----------



## pepar

Quote:

Originally Posted by *nathan_h* 
Actually as Denis' response implies, as long as no one is sitting precisely on axis, the whole off axis area is pretty decently consistent.


This is pretty easy to set up for every speaker other than the center channel.
Purposely aim the speakers so no one is ON-axis??


Per M&K's recommendation, I have been using laser alignment tool to aim my speakers precisely at the 3D geometrical center of the listening area to minimize the degree of off-axis ears. And my last re-design when moving to a 2.35 AT screen, I lowered the LCR to minimize the +/- distance of the ears in the vertical dimension.











But maybe that's the difference between working with well-behaved speakers (off-axis) and .. not?


Jeff


----------



## nathan_h

Quote:

Originally Posted by *pepar* 
Purposely aim the speakers so no one is ON-axis??


Jeff
Exactly. In fact, some speakers are designed to be used that way.


In the two channel world, most models of Thiel speakers are recommended to be NOT toe-ed in. That is, the speakers are designed to sound correct when pointed at a space to the left and right of the listener, rather than when pointed at the listener.


To Denis' point, the ideal speaker, esp for home theater, has a consistent, mild variation from on axis to a little off axis to a lot of off axis.


To tie that together with the B&W graphs, once one gets a little off axis, things behave in that nice way.


----------



## pepar

Quote:

Originally Posted by *nathan_h* 
To tie that together with the B&W graphs, once one gets a little off axis, things behave in that nice way.
OK, but they are no where near flat off axis ... or isn't that important?










Jeff


----------



## Norman Varney

You should use your ears first to optimize the toe-in for soundstage. Different speakers will interact differently in every different room and layout. Once you have determined optimum soundstage, use your laser to shoot beyond your listening position, which will give more accurate readings for fine-tuning. Be sure to bubble level the speakers first for accuracy and/or symmetry.


----------



## smokarz




> Quote:
> Originally Posted by *mtbdudex* /forum/post/19908230
> 
> 
> Hanging 101 for DIY framed 2' x 4' acoustic panels:
> 
> (I just got done hanging this 6th panel tonight).........



hey mtbdudex, thanks so much for sharing.


i noticed that you only wrapped the OC703 only, instead of the whole frame.


how did you keep the OC in the frame, so it doesn't fall out? i see 2 back panels support, but how about the front?


----------



## Dennis Erskine

Some how the point is being missed:


1. No speaker will be flat off axis.

2. The off axis plot should have the same shape and character as the angle increases. Note the good response ... the shape, is the same at all angles ... is just rolls off on the high end. Basically, the frequency response is exactly the same...just the SPL rolls off.

3. Look at the bad response ... the off axis picks up a notch. That is bad, bad, bad. When your off axis doesn't match your on axis, you want to absorb. When it does you want diffusion. In the case of the B&W plots, the FR of the on axis and off axis are very different. Not good.


----------



## AZGAMD




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19924182
> 
> 
> this whole live-end/dead-end business all started due to a popular speaker (at the time in the 80's) which had awful off axis response and that was the fix.



Does this mean making the front of the room dead and back live is not needed?


----------



## pepar




> Quote:
> Originally Posted by *AZGAMD* /forum/post/19926444
> 
> 
> Does this mean making the front of the room dead and back live is not needed?



Having an AT screen (and screenwall), I guess I am confused about this as well. The THX folks recommended the cavity be deadened, and Ken Kreisel (M&K) does as well.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19926730
> 
> 
> Having an AT screen (and screenwall), I guess I am confused about this as well. The THX folks recommended the cavity be deadened, and Ken Kreisel (M&K) does as well.



FWIW, I deadened the area around and between my LCR speakers, flush with their baffles behind an AT screen and intelligibility is really excellent. I don't know how it could be better. As the reporter retreats into Hugo's chicken shack in Season 3 of Lost, you can hear her mutter "I hate these assignments, everyone's got a story." plain as day at comfortable volume levels for the rest of the audio. It's a throw-away line, but my Lost addicted neighbors burst out laughing. "We never heard THAT!"


----------



## Jay5298

Dennis,


I sent my pics and room dimensions to Mike Orlowski at AlpineVista.com, he is busy with another client at the moment. Being that I don't have a laptop computer and am unable to take measurements myself, specifically the response of my speakers. I got this from Paradigm's site on the Studio 60s, now mine are the V4s but the specs are the same.

Frequency Response:

On-Axis

30° Off-Axis

±2 dB from 45 Hz - 22 kHz

±2 dB from 45 Hz - 20 kHz

Does this information help without taking any actual measurements?


Thanks


----------



## Dennis Erskine

Jay ... no. Measurements are required since the room has the bigger impact. Positioning counts, seating locations count, etc.


...of course cavities have to be deadened which is different from the LEDE adopted in early two channel, free standing arrangements.


THX is talking about baffle walls and the cavity behind the baffle is deadened to avoid resonance. There's also the SBIR notch issue to be cautious about.


----------



## AZGAMD




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19928420
> 
> 
> ...of course cavities have to be deadened which is different from the LEDE adopted in early two channel, free standing arrangements.
> 
> 
> THX is talking about baffle walls and the cavity behind the baffle is deadened to avoid resonance. There's also the SBIR notch issue to be cautious about.



Alright, I understand the front cavity needs to be dead, but what about the opposite end. Does it need to be live? Or is this not standard and needs to be determined on a case by case basis?


----------



## matthewa

Hi Guys,


Couldn't see this mentioned in the thread, but I was wondering has anyone used these kits for treating their theatre room, are these appropriate or are they setup only to work for a recording studio?

http://vintagemicrophone.com/JShop/p...d2fb22c7b3c64d 


Cheers,


Matt


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> OK, but they are no where near flat off axis ... or isn't that important?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



My read is that flat is not possible. The goal: Consistent response as the off axis angle increases. That is, gradual change. No way to be flat but one wants to avoid radical changes over the space of a few degrees.


----------



## mtbdudex




> Quote:
> Originally Posted by *price3* /forum/post/19903099
> 
> 
> Has anyone ever used stone as a diffusing medium? I have some left over from a fireplace and could use it in a strip on my rear wall if it would be beneficial. This is the only pic I could find:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Also, if making soffit bass traps, with 1/2" sheetrock covering loose insulation should I cut vents in or leave it sealed?





> Quote:
> Originally Posted by *nathan_h* /forum/post/19903948
> 
> 
> Stone would be better than a flat wall, but to be predictably effective would need to have bigger peaks and valleys than in that photo. That looks like a visual flourish but not an effective sound treatment.
> 
> 
> You want something much thinner than half inch Sheetrock covering a bass trap. Examples: fabric, foil, paper. If you look at some of the build threads here you'll see some creative solutions. Example, one whole side is left unsheetrocked and is covered with fabric.





> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19903965
> 
> 
> That won't work very well for various reasons, mostly because there's not enough depth. More here:
> 
> All About Diffusion
> 
> 
> 
> 
> A soffit as you describe will not work as a bass trap because sheet rock is too dense to let bass waves pass through to the insulation inside. You need to make a wood frame, then stretch fabric (or staple cardboard) to the frame.
> 
> 
> --Ethan



Kinda related, while doing tile work in my basement I saw these in the store and they reminded me of the diffusers I was reading about while doing some of my acoustic research 1+ year ago.

Yea, they look like them somewhat but depth is too shallow and I'm sure their pattern does not follow some 7th order function...

Wonder how heavy they'd be if built "properly".....100's lbs?

















Since I'm in a log home I was looking for some more natural/organic material for diffusors than the metal/plastic ones I've come across.

Some of those commercial wood ones are really neat looking, and with science behind them.

















The DIY wood ones seem like lots of work....(this is from a 3 year old thread with Ethan also in it, http://recording.org/studio-construc...mparisons.html )


----------



## mtbdudex




> Quote:
> Originally Posted by *smokarz* /forum/post/19925897
> 
> 
> hey mtbdudex, thanks so much for sharing.
> 
> 
> i noticed that you only wrapped the OC703 only, instead of the whole frame.
> 
> 
> how did you keep the OC in the frame, so it doesn't fall out? i see 2 back panels support, but how about the front?



I've been thinking to make a separate thread on the DIY construction methods of hanging acoustic panels, currently none exist, I've searched AVS forum.

Just these for Fabric frames, which are integrated as part of the wall itself, not hanging and locatable to where only needed.

(these are great threads btw for those whole wall coverage methods)
Fabric Frames - GPowers Thread 
Another Fabric Frame Thread - Canvas Stretcher Bars 


I'll start it later, and others can then add their methods there.

IMO, this "Master treatments" thread is more for the theory, science, and practical application for acoustics of your particular room situation/issue, not the DIY construction methods, that will clutter it too much.


Having separate DIY construction technique thread will keep that ready for others to grasp as well, this 100's pages thread can be overwhelming at times.


----------



## Dennis Erskine

You certainly do not want the back wall "dead" if you have surround speakers back there. The extent to which that wall is treated, and exactly with what, is dependent upon many factors ... distance from speakers, distance from nearest row, available height for rear speaker installation, overall decay rate by frequency in the room, where are the side surrounds (and type), etc.


----------



## smokarz

Quote:

Originally Posted by *mtbdudex* 
I've been thinking to make a separate thread on the DIY construction methods of hanging acoustic panels, currently none exist, I've searched AVS forum.

Just these for Fabric frames, which are integrated as part of the wall itself, not hanging and locatable to where only needed.

(these are great threads btw for those whole wall coverage methods)
Fabric Frames - GPowers Thread 
Another Fabric Frame Thread - Canvas Stretcher Bars 


I'll start it later, and others can then add their methods there.

IMO, this "Master treatments" thread is more for the theory, science, and practical application for acoustics of your particular room situation/issue, not the DIY construction methods, that will clutter it too much.


Having separate DIY construction technique thread will keep that ready for others to grasp as well, this 100's pages thread can be overwhelming at times.
great idea.


i agreed this is probably not the right thread for diy panels, and frankly the size of this thread and its content is overwhelming for people looking for diy materials.


please post link when you get a chance to getting around on creating this new thread.


thanks


----------



## Jay5298




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19928420
> 
> 
> Jay ... no. Measurements are required since the room has the bigger impact. Positioning counts, seating locations count, etc.
> 
> 
> ...of course cavities have to be deadened which is different from the LEDE adopted in early two channel, free standing arrangements.
> 
> 
> THX is talking about baffle walls and the cavity behind the baffle is deadened to avoid resonance. There's also the SBIR notch issue to be cautious about.



Okay, well I guess I'll wait to hear from Mike about what to do with my room. I still think I'm safe to put corner bass traps in though.


Thanks


----------



## Ethan Winer




> Quote:
> Originally Posted by *matthewa* /forum/post/19929318
> 
> 
> I was wondering has anyone used these kits for treating their theatre room, are these appropriate or are they setup only to work for a recording studio?



I don't see enough detail there to know what's included, but it's better to work with a treatment manufacturer directly who will guide you and make sure you get what's most appropriate for _your specific_ room. In my experience, few resellers understand acoustic treatment well enough to advise specific products and placement etc.


--Ethan


----------



## nathan_h




> Quote:
> Originally Posted by *matthewa* /forum/post/19929318
> 
> 
> Hi Guys,
> 
> 
> Couldn't see this mentioned in the thread, but I was wondering has anyone used these kits for treating their theatre room, are these appropriate or are they setup only to work for a recording studio?
> 
> http://vintagemicrophone.com/JShop/p...d2fb22c7b3c64d
> 
> 
> Cheers,
> 
> 
> Matt



Heck, for that price spend a few hundred bucks for a pro to come measure your room and tell you what to get and where to place it. Overall you'll likely spend less, and get a better (ie, perfect fit) solution.


EDIT: At the very least, Ethan's suggestion to have one of the expert vendors advise you is worthwhile. No cost for those remote consults, though it's of course polite to purchase at least some of what they sell.


----------



## Johnnydc

Hello everyone. I am a newbie to the site and was told to come to this thread for a good response. First, I am turning a large frog into a dedicated theater room (except for a few pieces of excercise equiptment that the wife has to keep in there). I would love to see some pics and get advice from some theater room owners that did a great job at "faking luxury" using some sort of curtains on all the walls for the "theater look", and of course for the benefit of sound dampening (doesn't have to be red velvet, can be any color and any material...I'm really looking for a cheap way to get the best theater look). I am thinking of running painted black dowels down the ceiling of the entire room, and using simple clearance curtains from Lowes that will reach the floor. There are so many responses on where to put curtains as well. here's my set up: rectangular room, entrance to room has large built ins where 50 Panasonic will be mounted, subs in bottom niches (large niches). do i put curtains over this stuff as well?? do I put it along all walls and in back?? There is a double window in the back of the room. This will be a 7.2 system (maybe 7.1 depending on the response I get from the sub-heads).

I have a 2 sub question as well , but will be posting it in the sub forums unless I have any subbies on this forum.

Basically here's my equiptment: Harmon kardon reciever, 50 panasonic plasma, 1 jbl powered 8sub, 1 veladyne powered 8, sony and jbl satalite speakers for front, mid, rear, and sony center channel.


----------



## mtbdudex

Here is the thread I just started in this same forum, called DIY construction methods of hang-able acoustic panels (not fixed frames) 


I'd like others who make DIY hang-able acoustic panels, whether absorption, diffusion, reflection, etc. to also feel free to add your construction techniques/methods there.

>>We need to learn from you!




> Quote:
> Originally Posted by *smokarz* /forum/post/19931135
> 
> 
> 
> 
> Quote:
> Originally Posted by *mtbdudex* /forum/post/19929825
> 
> 
> I've been thinking to make a separate thread on the DIY construction methods of hanging acoustic panels, currently none exist, I've searched AVS forum.
> 
> Just these for Fabric frames, which are integrated as part of the wall itself, not hanging and locatable to where only needed.
> 
> (these are great threads btw for those whole wall coverage methods)
> Fabric Frames - GPowers Thread
> Another Fabric Frame Thread - Canvas Stretcher Bars
> 
> 
> I'll start it later, and others can then add their methods there.
> 
> IMO, this "Master treatments" thread is more for the theory, science, and practical application for acoustics of your particular room situation/issue, not the DIY construction methods, that will clutter it too much.
> 
> 
> Having separate DIY construction technique thread will keep that ready for others to grasp as well, this 100's pages thread can be overwhelming at times.
> 
> 
> 
> 
> great idea.
> 
> 
> i agreed this is probably not the right thread for diy panels, and frankly the size of this thread and its content is overwhelming for people looking for diy materials.
> 
> 
> please post link when you get a chance to getting around on creating this new thread.
> 
> 
> thanks
Click to expand...


----------



## Bills Fan

Looking for a reccomendation for a company to install a LCD TV and run the wires behind the wall.


----------



## pepar




> Quote:
> Originally Posted by *Bills Fan* /forum/post/19955922
> 
> 
> Looking for a reccomendation for a company to install a LCD TV and run the wires behind the wall.



Had you considered posting this in a thread more closely related to installing an LCD and running wires inside the wall? Include a location, too. "Bills Fan" might say it, but you could be a translpant as well.


----------



## Tolstoi

I currently through a threads on construction projects to say how peoples did it. Doing this I came up with questions related to soundproofing.


1) I want to use tubing to be used a cables channels between the rack and near each speakers. I saw that almost all setup pass their tubing through the ceiling. I was planning to pass my tubing under the floor to try to get shorter cable runs. Soundproofing wise is their a benefit of method was to other?


2) Does the soffit add anything acoustic wise or are they strictly there for cosmetic reasons? Do they need to be symmetrical?


3) One of my walls is made of 2x6 on which I am using sound clips and hat channels. What should I do soundproofing wise with that extra 2" compare with 2x4 structure? Increase the 1" air space between the R13 pink insulation and gypsum? Increase the pink insulation thickness to 5"1/2?


----------



## dallaslistener

Hey Guys,


My wife and I built a fairly large dedicated HT a couple of years ago. At the time we hired an acoustics "consultant" to help with the design and construction. He provided a set of plans and after it was too late, we discovered that many of the "acoustical" tricks he had recommended had been mis-communicated to our builder in the beginning and it was too late to implement most of them. Things such as built in corner bass traps and soffit diffusers and so on and so on. In addition, they would have made the aesthetics of the theater horrible. When challenged by myself and the builder, it became obvious that the guy had sub contracted the whole design and drawing set to someone else and he really didn't know what he was talking about. There were actually two aspects to the construction, the sound proofing / isolation of the room from the rest of the house and the interior acoustical treatment. We got the isolation stuff right from the start. But the interior treatment stuff didn't get implemented.


At first pass, the room seems to sound pretty good but I would really like to take some analytical measurements and begin experimenting with acoustical treatments. So my question is what instrumentation do I acquire? Computer? Software? Mics? Etc? This may have been covered already and if so I apologize for repeating. Just point me to the right thread. I have a EE degree so I'm not scared of the in depth technical stuff. I've also been a lifelong "audiophile" for what that's worth - if anything 


Thanks

Dale Troutt

Frisco TX


----------



## Ethan Winer




> Quote:
> Originally Posted by *dallaslistener* /forum/post/19964811
> 
> 
> what instrumentation do I acquire?



Here's my standard list of room measuring links:

Room EQ Wizard, Windows and Linux and Mac OSX 10.4+, Freeware 
ETF, Windows, $150 
FuzzMeasure, Mac, $150 
Room Measuring Primer 
Comparison of Ten Measuring Microphones 


--Ethan


----------



## pepar

Laptop, USB sound "card" or preamp, Room EQ Wizard and a calibrated mic. But it will be the time needed to get around the learning curve .. or "curb" depending on how well you assimilate. But even then with measurements in your hand you may not know what they mean. I don't mean to dissuede you, but you have a bit of a daunting task ahead.


You might consider a design service like the one offered here by AVS or Dennis Erskine.


Also, acoustical treatment vendors such as Ethan Winer and GIK Acoustics offer design recommendations as part of their customer service.


----------



## erkq

I have a "flutter" echo in the back of my theater. Fortunately it doesn't seem to get activated by the speakers. I just unscientifically covered the walls with 1" black-faced fiberboards and it went away with great audio clarity. But talk of "over damping" got me to experiment with positioning absorption using the "mirror test". The results are again very clear and satisfactory, but if I go to the back of the theater and even utter a "sss" I hear the flutter echo.


The room is a little complicated back there. The 6' wide projection booth juts out a foot creating a 1' deep 6' wide alcove on one side (I'd like to eventually use for a huge bass trap) and a 4.5' entryway on the other. Not only that, but the ceiling starts at 12' and pitches up to 17' about midway to the screen.


So there could be lots of places the flutter echo is occurring. I'd like to measure the flutter's period because that would give me the dimension to look for. How can I do that? A 'scope might be good but I don't have one. Can REW do this? I have that, a laptop and a calibrated mic. Is it worth setting those up and playing with available measurements and graphs?


----------



## Iusteve

A while back I asked if it was a good/bad idea to use OC 703 and fabric on all vertical surfaces in my theater and was told not to do so. So my next simple question without asking for a too complex answer. Is it ok to use OC 703 and fabric on both side walls to chair rail height or basicially 4ft? Also what about the rear wall? Chair rail or floor to ceiling?


----------



## dallaslistener

Ethan,


Thanks so much for the recommendations. I am a MAC computer guy primarily. I have a MAC Book Air and a MAC Desktop (both a couple of years old) and I've been thinking about buying a Mini to hook up to the Theater. My question is will REW do all the same stuff as FuzzMeasure or do I need to get both. Will I be giving up anything significant by not going Windows? Also, where do I buy one of the recommended mics and will I need an external mic preamp with a MAC? If so, which one and where to buy?


Thanks Again

Dale


----------



## erkq




> Quote:
> Originally Posted by *dallaslistener* /forum/post/19968365
> 
> 
> Ethan,
> 
> 
> Thanks so much for the recommendations. I am a MAC computer guy primarily. I have a MAC Book Air and a MAC Desktop (both a couple of years old) and I've been thinking about buying a Mini to hook up to the Theater. My question is will REW do all the same stuff as FuzzMeasure or do I need to get both. Will I be giving up anything significant by not going Windows? Also, where do I buy one of the recommended mics and will I need an external mic preamp with a MAC? If so, which one and where to buy?
> 
> 
> Thanks Again
> 
> Dale



I'm not Ethan but I settled on a LinearX M31 calibrated mic. It comes with its response curve both on paper and on a mini-cd. You can enter the curve into REW, but the it's so flat it hardly seems worth it.


I used a Behringer Mini-Mic Modelling Pre-Amp. Just set the "effects" to neutral. It seemed to be the best deal for an ultra-wide band flat pre-amp. There is a procedure to have it measure itself via a loop, but it's hardly worth it to find the -1dB points when the room response is so much more variable.


They're each around $125 or so.


I forget where I got them. I can look it up if you are interested.


----------



## dallaslistener

ERKG,


Thanks. I Googled them and found a few places to buy them. Did you use a MAC or PC?


Dale


----------



## erkq




> Quote:
> Originally Posted by *dallaslistener* /forum/post/19968496
> 
> 
> ERKG,
> 
> 
> Thanks. I Googled them and found a few places to buy them. Did you use a MAC or PC?
> 
> 
> Dale



Unfortunately a PC. I run HCFA on it too. It's a pretty slick little test rig.


----------



## dallaslistener

HCFA? I'm not familiar with that. If I get a MAC Mini, how much memory do I need for these apps?


----------



## erkq




> Quote:
> Originally Posted by *dallaslistener* /forum/post/19968713
> 
> 
> HCFA? I'm not familiar with that. If I get a MAC Mini, how much memory do I need for these apps?



HCFA is a very good free color calibration system. It's really OT here. I was just adding to why I use a PC.


You don't need much memory. Most of your memory load will be running the OS. These are pretty simple programs in comparison to the bloatware Microsoft gives us. Would you be running Bootcamp or Parallels on the Mini? Has anyone else here done that? It should work... I just don't know from experience.


----------



## systemlayers

Hi everyone been reading this thread intently - definitely not ready to pull the gun anytime soon but i've been looking into obtaining some rigid fiberglass in Edmonton Canada.

I found this large distributer and their rigid fiberglass:
http://www.crossroadsci.com/PRODUCTS...3/Default.aspx 

It seems to have similar sound coefficients and thickness to the owens corning 703 will this be sufficient or should i search elsewhere/more?


----------



## mtbdudex

This past weekend continuing with improving the HT acoustics, I put (6) sheets of 2" thick 2' x 4' Roxul Rockboard on my screen to make is a "dead zone" instead of a resonance/reflection zone.

Dennis E suggested this to me almost 2 years ago, was on my "to do" list, finally did it this weekend.
http://www.atsacoustics.com/item--Ro...f-6--RB60.html 


> Quote:
> This is a case of 6 pieces of 24 x 48 x 2 inch Rockboard 60 manufactured by Roxul. It is rigid mineral wool board similar to Owens Corning 705 at a density of 6 pounds per cubic foot.



I used Roxul Rockboard instead of OC705 because I am NOT going to cover it, so did not want itchy stuff.


This is on back of my DIY screen, there is a controlled 3/4" gap to the DW laminate screen via the metal plates I added for supporting, secured the panels by suspended ceiling 14ga wire.










Final product done and secured, the outside portion has (2) 2" thick 2 ' x 4' pieces fitting, the inside (1) due to screen curve allows more on outside.










It's also with about a 3" air gap to the wall now.










screen hung, btw It's also 50 lbs heavier.....my wife complained I'm "slaving her" with all this heavy lifting.:









(that's my acoustic cloud I'm making just today, it was not there when I did the Audyessy re-run)


I immediately could tell improved bass, I've not taken REW plots yet, but I did re-run my Audyessy and it shows how its EQ is applied, look at the before/after for the center channel!

Yes, I was very careful about having my mic in repeatable positions as well for before/after check..

Plus, before Audyessy always set my Paradigm 9 mains Frt RH/LH to large, but the huge CC-390 center to small, now it also was set to Large, indicating it recognized it's lower freq potential better with the improved acoustics.

Note: The front of the center channel is about 29" from the back wall, that's as far as I could put it "in room" on the shelf I made, the mains are similar, plus 24" off the side walls.

Before...................................................... .......After:


----------



## Iusteve

*My question got buried so I figured I would attempt one more time*



A while back I asked if it was a good/bad idea to use OC 703 and fabric on all vertical surfaces in my theater and was told not to do so. So my next simple question without asking for a too complex answer. Is it ok to use OC 703 and fabric on both side walls to chair rail height or basicially 4ft? Also what about the rear wall? Chair rail or floor to ceiling?


----------



## Brad Horstkotte

The best answer is "it depends", and requires acoustic measurement. However, many have followed that general approach (floor to just above ear level on side and rear walls) and are happy with it.


----------



## erkq




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19970047
> 
> 
> The best answer is "it depends", and requires acoustic measurement. However, many have followed that general approach (floor to just above ear level on side and rear walls) and are happy with it.



How does this jibe with the "mirror test" which is how my room is configured now? It turned out to be wall coverage from just in from of the screen to almost parallel with the last seating position for that right speaker to left rear listener reflection. The covering goes up to 70" to cover the positions on the riser. I figured a little over-coverage was OK to make sure the reflections were "gotten". So much of the walls are left bare I figured I'd have enough "liveness". It sounds good... intelligibility is very good.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/19970661
> 
> *How does this jibe with the "mirror test" which is how my room is configured now?* It turned out to be wall coverage from just in from of the screen to almost parallel with the last seating position for that right speaker to left rear listener reflection. The covering goes up to 70" to cover the positions on the riser. I figured a little over-coverage was OK to make sure the reflections were "gotten". So much of the walls are left bare I figured I'd have enough "liveness". It sounds good... intelligibility is very good.



It doesn't. And I can tell you that I regret covering floor-to-ear level with carpet, an idea that I got 10-15 years ago from an acoustic handbook. My system sounds very good, dialog intelligibility is perfect regardless of the level of the dialog or the level of the rest of sounds.


But my room also seems a bit dead and I am looking at swapping the absorption at the first reflection points for diffusion. "Thinking" has changed, and so must I.


Jeff


----------



## erkq

Or maybe no one has an answer:


I have a "flutter" echo in the back of my theater. Fortunately it doesn't seem to get activated by the speakers. I just unscientifically covered the walls with 1" black-faced fiberboards and it went away with great audio clarity. But talk of "over damping" got me to experiment with positioning absorption using the "mirror test". The results are again very clear and satisfactory, but if I go to the back of the theater and even utter a "sss" I hear the flutter echo.


The room is a little complicated back there. The 6' wide projection booth juts out a foot creating a 1' deep 6' wide alcove on one side (I'd like to eventually use for a huge bass trap) and a 4.5' entryway on the other. Not only that, but the ceiling starts at 12' and pitches up to 17' about midway to the screen.


So there could be lots of places the flutter echo is occurring. I'd like to measure the flutter's period because that would give me the dimension to look for. How can I do that? A 'scope might be good but I don't have one. Can REW do this? I have that, a laptop and a calibrated mic. Is it worth setting those up and playing with available measurements and graphs?


----------



## mtbdudex




> Quote:
> Originally Posted by *erkq* /forum/post/19970661
> 
> 
> How does this jibe with the "mirror test" which is how my room is configured now? It turned out to be wall coverage from just in from of the screen to almost parallel with the last seating position for that right speaker to left rear listener reflection. The covering goes up to 70" to cover the positions on the riser. I figured a little over-coverage was OK to make sure the reflections were "gotten". So much of the walls are left bare I figured I'd have enough "liveness". It sounds good... intelligibility is very good.





> Quote:
> Originally Posted by *pepar* /forum/post/19970789
> 
> 
> It doesn't. And I can tell you that I regret covering floor-to-ear level with carpet, an idea that I got 10-15 years ago from an acoustic handbook. My system sounds very good, dialog intelligibility is perfect regardless of the level of the dialog or the level of the rest of sounds.
> 
> 
> But my room also seems a bit dead and I am looking at swapping the absorption at the first reflection points for diffusion. "Thinking" has changed, and so must I.
> 
> 
> Jeff



fwiw, I calculated my desired RT60 for 0.5 sec, now I am in process of putting that absorption at first reflection points (side walls done, ceiling in progress), this way there was some science behind it.


Panels AddedResulting Reverb Time - RT60Square FeetCount125Hz250Hz500Hz1000Hz2000Hz4000HzBaseline drywall + carpet0 sq.ft.0 panels0.41.091.340.770.480.42treated with 6 side wall 2" and 6 ceiling 4" panels96 sq.ft.12 panels0.380.640.560.420.310.29

I'm sure you guys have read this by Ethan W?.
http://www.realtraps.com/rfz.htm 


I can't say how mine will turn out, but with some rationale of following a method, I can so far see good results as each phase goes on.


[edit]

hey erkq, hopefully Ethan or Terry or another expert will chime in for your Q


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/19970872
> 
> 
> Or maybe no one has an answer:
> 
> 
> I have a "flutter" echo in the back of my theater. Fortunately it doesn't seem to get activated by the speakers. I just unscientifically covered the walls with 1" black-faced fiberboards and it went away with great audio clarity. But talk of "over damping" got me to experiment with positioning absorption using the "mirror test". The results are again very clear and satisfactory, but if I go to the back of the theater and even utter a "sss" I hear the flutter echo.
> 
> 
> The room is a little complicated back there. The 6' wide projection booth juts out a foot creating a 1' deep 6' wide alcove on one side (I'd like to eventually use for a huge bass trap) and a 4.5' entryway on the other. Not only that, but the ceiling starts at 12' and pitches up to 17' about midway to the screen.
> 
> 
> So there could be lots of places the flutter echo is occurring. I'd like to measure the flutter's period because that would give me the dimension to look for. How can I do that? A 'scope might be good but I don't have one. Can REW do this? I have that, a laptop and a calibrated mic. Is it worth setting those up and playing with available measurements and graphs?



As I understand it, flutter echo happens between two parallel reflective surfaces. I'm sure you knew that ...







... and I would also think they'd be easy to spot?


----------



## nathan_h




> Quote:
> Originally Posted by *Iusteve* /forum/post/0
> 
> 
> My question got buried so I figured I would attempt one more time
> 
> 
> A while back I asked if it was a good/bad idea to use OC 703 and fabric on all vertical surfaces in my theater and was told not to do so. So my next simple question without asking for a too complex answer. Is it ok to use OC 703 and fabric on both side walls to chair rail height or basicially 4ft? Also what about the rear wall? Chair rail or floor to ceiling?



As others have said, Don't do it. Use the mirror method instead as a "best bet" if you don't have time/money for measurements and/or a professional service to assist.


----------



## nathan_h




> Quote:
> Originally Posted by *erkq* /forum/post/0
> 
> 
> Or maybe no one has an answer:
> 
> 
> I have a "flutter" echo in the back of my theater. Fortunately it doesn't seem to get activated by the speakers. I just unscientifically covered the walls with 1" black-faced fiberboards and it went away with great audio clarity. But talk of "over damping" got me to experiment with positioning absorption using the "mirror test". The results are again very clear and satisfactory, but if I go to the back of the theater and even utter a "sss" I hear the flutter echo.
> 
> 
> The room is a little complicated back there. The 6' wide projection booth juts out a foot creating a 1' deep 6' wide alcove on one side (I'd like to eventually use for a huge bass trap) and a 4.5' entryway on the other. Not only that, but the ceiling starts at 12' and pitches up to 17' about midway to the screen.
> 
> 
> So there could be lots of places the flutter echo is occurring. I'd like to measure the flutter's period because that would give me the dimension to look for. How can I do that? A 'scope might be good but I don't have one. Can REW do this? I have that, a laptop and a calibrated mic. Is it worth setting those up and playing with available measurements and graphs?



REW will be great in a space like this. Interpreting the results and turning those into actions will rely on your own extensive research and or on the kindness of strangers looking at your results and hearing about your process, online.


----------



## Ethan Winer




> Quote:
> Originally Posted by *dallaslistener* /forum/post/19968365
> 
> 
> will REW do all the same stuff as FuzzMeasure or do I need to get both.



If REW works on your particular Mac then that's all you need.



> Quote:
> where do I buy one of the recommended mics and will I need an external mic preamp with a MAC? If so, which one and where to buy?



I don't know if your Mac has a preamp, but my * Room Measuring Primer * shows hardware that will work. Or buy the microphone and sound card from a dealer who knows Macs, and they'll know what to suggest. There are tons of good vendors such as Sweetwater and Vintage King and Musician's Friend and American Musical.


--Ethan


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19971092
> 
> 
> As I understand it, flutter echo happens between two parallel reflective surfaces. I'm sure you knew that ...
> 
> 
> 
> 
> 
> 
> 
> ... and I would also think they'd be easy to spot?



Yes. The complexity of the room gives several possibilities for reflecting parallel surfaces. I guess I could just experiment and see what REW will tell me as nathan_h suggests. It's just hard to hang stuff 17' up, so I wanted to try to cut down on the possibilities before I start climbing the ladder.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/19971521
> 
> 
> Yes. The complexity of the room gives several possibilities for reflecting parallel surfaces. I guess I could just experiment and see what REW will tell me as nathan_h suggests. It's just hard to hang stuff 17' up, so I wanted to try to cut down on the possibilities before I start climbing the ladder.



I don't know how measurement software would identify the surfaces. I've always been able to find the culprits with my ears a few finger snaps. Yours sound like they are ... inconvenient, but the same process still applies .. snap your fingers and listen. It should be obvious which two surfaces are causing the echo.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19971713
> 
> 
> I don't know how measurement software would identify the surfaces. I've always been able to find the culprits with my ears a few finger snaps.



The period of the flutter would tell me the distance between the surfaces. That would point to specific surface pairs that have that distance between them.


All I can tell with my ears is that it's somewhere in the back of the room.


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/19971729
> 
> 
> The period of the flutter would tell me the distance between the surfaces. That would point to specific surface pairs that have that distance between them.
> 
> 
> All I can tell with my ears is that it's somewhere in the back of the room.













Front/back? Left/right? Up/down?


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/19971713
> 
> 
> I don't know how measurement software would identify the surfaces.



The Impulse Response (or Energy / Time) display shows individual reflections and their arrival time. So you can figure the distance of a reflecting surface. I don't use that feature much, but I might if the alternative was climbing 17 feet up on a ladder!


--Ethan


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19971827
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Front/back? Left/right? Up/down?



It's hard to tell, and that's my problem. There are 3 sets of parallel surfaces I suspect. I don't suspect the floor/ceiling surfaces because of a 6/12 pitch to ceiling.


----------



## erkq




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19972688
> 
> 
> The Impulse Response (or Energy / Time) display shows individual reflections and their arrival time. So you can figure the distance of a reflecting surface. I don't use that feature much, but I might if the alternative was climbing 17 feet up on a ladder!
> 
> 
> --Ethan



That's what I'm looking for. Thanks. It seems it's worth playing with REW then.


----------



## dallaslistener

Ethan,


Thanks so much for the info. One more question - is basic mic calibration adequate or do I need the "premium" calibration?


Regards

Dale


----------



## smokarz

can anyone share some diy tips for constructing corner bass traps with OC 703? thanks


----------



## Kal Rubinson




> Quote:
> Originally Posted by *smokarz* /forum/post/19976479
> 
> 
> can anyone share some diy tips for constructing corner bass traps with OC 703? thanks



Best: http://forum.studiotips.com/viewtopic.php?t=535


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/19976479
> 
> 
> can anyone share some diy tips for constructing corner bass traps with OC 703? thanks



Enter here and you get an overview.


----------



## myfipie

Quote:

Originally Posted by *smokarz* 
can anyone share some diy tips for constructing corner bass traps with OC 703? thanks
The main thing you want to do is

1) Make them 4" or thicker

2) Make sure to keep the back open. As in do not cover with wood or anything rigid.

From there you can just frame them up with wood and cover with fabric.


The other option is to cut the fiberglass to 24"x17" triangles and stack them floor to ceiling, then put a false fabric wall in front of that.


----------



## smokarz

Quote:

Originally Posted by *myfipie* 
The main thing you want to do is

1) Make them 4" or thicker

2) Make sure to keep the back open. As in do not cover with wood or anything rigid.

From there you can just frame them up with wood and cover with fabric.


The other option is to cut the fiberglass to 24"x17" triangles and stack them floor to ceiling, then put a false fabric wall in front of that.
thanks, i was asking specifically about corner bass trap.


cutting the OC 703 into triangles, and stack them up. but what are people doing? are they building triangle frames to house these stacks of OC 703?


----------



## smokarz




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/19976587
> 
> 
> Best: http://forum.studiotips.com/viewtopic.php?t=535





> Quote:
> Originally Posted by *pepar* /forum/post/19976678
> 
> 
> Enter here and you get an overview.



thanks, but looking for details diy instructions for corner bass.


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/19977513
> 
> 
> thanks, i was asking specifically about corner bass trap.
> 
> 
> cutting the OC 703 into triangles, and stack them up. but what are people doing? are they building triangle frames to house these stacks of OC 703?



For a hidden trap, you could do it this way . For an exposed trap, my idea is to use angle brackets bent into a 45 degree and mounted "inside" the retaining slats with a cover panel made and velcro'd onto the slats.


That is up next for me ... more superchunk traps in the rear of my theater.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/19977752
> 
> 
> thanks, but looking for details diy instructions for corner bass.



Well, "corner" traps can be the panels straddling the corner or they can be the filled, chunk style. Your original post didn't specify any design in particular so I linked to both styles with comparative test data.


----------



## nathan_h




> Quote:
> Originally Posted by *smokarz* /forum/post/19977513
> 
> 
> thanks, i was asking specifically about corner bass trap.
> 
> 
> cutting the OC 703 into triangles, and stack them up. but what are people doing? are they building triangle frames to house these stacks of OC 703?



Exactly.


----------



## Ethan Winer




> Quote:
> Originally Posted by *dallaslistener* /forum/post/19973942
> 
> 
> is basic mic calibration adequate or do I need the "premium" calibration?



Most likely you don't need any calibration. This shows a comparison of microphones at widely varying price points:

Comparison of Ten Measuring Microphones 


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19977830
> 
> 
> Most likely you don't need any calibration. This shows a comparison of microphones at widely varying price points:
> 
> Comparison of Ten Measuring Microphones
> 
> 
> --Ethan



I must compliment you on the wealth of useful information that you have put together and placed on your website.


Jeff


----------



## erkq




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19977830
> 
> 
> Most likely you don't need any calibration. This shows a comparison of microphones at widely varying price points:
> 
> Comparison of Ten Measuring Microphones
> 
> 
> --Ethan



The LinearX I used came with a response graph and included each individual piece of equipment used in the measurement and when it was due for its next calibration.


Basically it shows Ethan is right. It is 1/4 dB down at 10Hz, 1/2 dB down at 25kHz and 1/3 dB up from 20Hz to 300Hz. I mean... so what? That is an insignificant level of precision when measuring a room. But I entered the curve into REW just for fun.


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/19977787
> 
> 
> For a hidden trap, you could do it this way . For an exposed trap, my idea is to use angle brackets bent into a 45 degree and mounted "inside" the retaining slats with a cover panel made and velcro'd onto the slats.
> 
> 
> That is up next for me ... more superchunk traps in the rear of my theater.
> 
> 
> Jeff



thanks, i thought i saw that before.


my "chunky" corner bass trap will be exposed. so i am thinking perhaps some sort of frame wrapped with fabric?


just trying to find some visual image of what people have done.


----------



## pauleyc




> Quote:
> Originally Posted by *pepar* /forum/post/19977787
> 
> 
> For a hidden trap, you could do it this way . For an exposed trap, my idea is to use angle brackets bent into a 45 degree and mounted "inside" the retaining slats with a cover panel made and velcro'd onto the slats.
> 
> 
> That is up next for me ... more superchunk traps in the rear of my theater.
> 
> 
> Jeff



Jeff - thanks for the link to your example. I'm getting some bass 'build up' in the second row of my home theater (pictures in link below) and I was thinking about doing the same 'super chunk' design in the rear two corners. All these are under the soffit and out of the way so functionality won't be compromised. I could probably do corners in the front as well since black on black disappears in a dark HT environment. So I may try that as well. I keep hearing you can't have too many bass traps










For the rear corners, I was thinking just left/right verticals w/ a 45 cut and maybe use your vertical wire idea if the OC703 isn't sturdy enough to stand on its own. Then its just a simple face frame grille. Here's an idea I plan to use ... before you fabric wrap the face frame, clamp it in place, drill a hole all the way through and then gluing a dowel in the face frame (or vertical nailers) so that you have a secure mount. I've had issues with Velcro and heavy panels.


Great info .. also thanks to Ethan - I've been reading a lot on your sight and even checked out a few of your youtube videos. While there is a lot of science behind it .. I get the impression that you can just keep adding with 'minimal' ill effects? (strictly speaking m-ch/HT)??

http://www.avsforum.com/avs-vb/showthread.php?t=1299530


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/19977912
> 
> 
> thanks, i thought i saw that before.
> 
> 
> my "chunky" corner bass trap will be exposed. so i am thinking perhaps some sort of frame wrapped with fabric?
> 
> 
> just trying to find some visual image of what people have done.



The only thing that keeps a cover from being fastened to the slats that hold the horizontal trap are the 1x2 hunks that hold the slats in place. Make them thin metal brackets internally mounted and that obstruction disappears. I'm sure that there are other designs that would work, but that's where I am headed.


For the cover, I will make something like this . My edge pieces will be cut at a 45 degree angle to snug up to the wall as close as possible.


----------



## pepar




> Quote:
> Originally Posted by *pauleyc* /forum/post/19978186
> 
> 
> Jeff - thanks for the link to your example. I'm getting some bass 'build up' in the second row of my home theater (pictures in link below) and I was thinking about doing the same 'super chunk' design in the rear two corners. All these are under the soffit and out of the way so functionality won't be compromised. I could probably do corners in the front as well since black on black disappears in a dark HT environment. So I may try that as well. I keep hearing you can't have too many bass traps
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> For the rear corners, I was thinking just left/right verticals w/ a 45 cut and maybe use your vertical wire idea if the OC703 isn't sturdy enough to stand on its own. Then its just a simple face frame grille. Here's an idea I plan to use ... before you fabric wrap the face frame, clamp it in place, drill a hole all the way through and then gluing a dowel in the face frame (or vertical nailers) so that you have a secure mount. I've had issues with Velcro and heavy panels.



To hold the vertical stack of 703 in place and give me something to fasten the covers to, I will use the slats. The wires were a down and dirty solution that was perfect for the hidden traps.


----------



## Brad Horstkotte

For my superchunks, I simply used drywall screws and liquid nails to affix 2 2x2s at 17" from the corners - then the triangles just stack in. Will staple a fabric face to the edges of the 2x2s. An easy approach if you're installing them permanently (vs a moveable trap).


----------



## fotto

I did just as Brad suggests for my front corner superchunks (hidden behind false screen wall). For my rear ones, I did a bit different:


----------



## pauleyc

Now I'm excited .. this is going to be a fairly easy project (in the scheme of things) thanks to the great info here. Now if I could just find a source in NoVA for OC703.


foto - Thanks for the pictures. Gave me some good ideas.


Jeff - What are your frames made out of? They are small. Any warping issues?


----------



## pepar




> Quote:
> Originally Posted by *pauleyc* /forum/post/19978682
> 
> 
> Jeff - What are your frames made out of? They are small. Any warping issues?



Poplar 1x2 ripped in half. Poplar is used for moldings because of its stability, but usually residences do not have large swings in relative humidity anyway. Plus the front of the theater is black and dark with no prominent "net fit" locations. My rear traps will not have the advantage of being hid.


Jeff


----------



## myfipie




> Quote:
> Originally Posted by *pauleyc* /forum/post/19978682
> 
> 
> Now I'm excited .. this is going to be a fairly easy project (in the scheme of things) thanks to the great info here. Now if I could just find a source in NoVA for OC703.
> 
> 
> foto - Thanks for the pictures. Gave me some good ideas.
> 
> 
> Jeff - What are your frames made out of? They are small. Any warping issues?



See if you have a SPI in your area.


----------



## Johnnydc

**********ACOUSTIC EXPERTS PLEASE READ ***********


> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/2176537
> 
> 
> First, (B) is wrong. Virtually every surface is a first reflective surface (speaking of walls). "B" is actually treating those early reflections which meet the listener's ears within a time frame described by Helmut Haas (further researched by Toole and Olive). Depending upon the delay due to the longer path to the ear will result in the sound being perceived as a distortion, or echo. As well, sounds reflecting off a surface suffer timbre shift. Next, you don't care a twit about "early reflections" that don't intersect the listening position.
> 
> 
> The 'early reflections' technique is more typically found in two channel playback environments where higher reverberation times in the room are required to make up for the absence of surround channels (or intelligent surround processing techniques).



Dennis, or anyone else who has acoustical treatment knowledge PLEASE read this and reply. I don't have it in my budget to professionally treat my new home theater room, but this is what I can do in my budget and want to know:

1. will MY SOLUTION do ANYTHING

2. What is the best layout for the curtains.

My SOLUTION: http://www.walmart.com/ip/Montego-Wo...Mocha/13269330 

Put these regular curtain panels with grommets on rods (regular 50x 102 panels spread enough to have a deep wave as shown in pics) spaced all along the side and back walls of my theater room with about 1 foot of space between each curtain panel (maybe for a sconce light or neat piece of artwork). Room is about 18x20+ room window in back and one door, front is built in shelves where plasma will be.

WILL THESE DO ANYTHING...SEEMS LIKE THE FOLDS WOULD STOP WAVES FROM BOUNCING AROUND IF NOTHING ELSE AND CATCH SOME SOUND. Please give me your sound advice. I think it will "look" great, but I won't spend even that amount of money (probably $200+) if it won't help the sound.


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/19979012
> 
> 
> See if you have a SPI in your area.



Northern VA? Yes, "Lancaster" ... PA ..







according to their site.










Actually, the Winfield, WV location might be closer ..


----------



## pauleyc




> Quote:
> Originally Posted by *myfipie* /forum/post/19979012
> 
> 
> See if you have a SPI in your area.





> Quote:
> Originally Posted by *pepar* /forum/post/19979034
> 
> 
> Northern VA? Yes, "Lancaster" ... PA ..
> 
> 
> 
> 
> 
> 
> 
> according to their site.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Actually, the Winfield, WV location might be closer ..



Lancaster is an easy drive (1.5hrs). I take my kids up there to Dutch Wonderland (good times). Winfield is close to where I grew up but is >7hrs from the WashDC area. While I get back home often, I don't think my wife and kids want to travel with that much OC703 in the van


----------



## Johnnydc

Hey guys, is my post, 7067 going to get lost here? any ideas for me? Just wondering if there is a more appropriate place for it or should I start a new thread.


----------



## PTAaron




> Quote:
> Originally Posted by *Johnnydc* /forum/post/19979115
> 
> 
> Hey guys, is my post, 7067 going to get lost here? any ideas for me? Just wondering if there is a more appropriate place for it or should I start a new thread.



There is a good chance that it will take longer than 15 minutes for someone to be able to reply to your post - I would give it at least a day, and if it gets buried start your own thread.


----------



## pepar

Curtains are window treatments, not acoustical treatments. Will they do *something?* Yes, something, but not anything meaningful. On the positive side, a few won't hurt.


And mocha is such a lovely color.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/19979806
> 
> 
> Curtains are window treatments, not acoustical treatments. Will they do *something?* Yes, something, but not anything meaningful. On the positive side, a few won't hurt.
> 
> 
> And mocha is such a lovely color.



Yes. I favorited that page. I want to do acoustic treatment and then cover it with drapes that pass the "breath" test. I like the ones he found.


----------



## Johnnydc

They are by far the cheapest, neatest ones that I have found. So, If I get two sets for each rod, would that do the trick? Also, how about the placement question...hang them with about a foot of wall space showing between each one (mostly to save money)?

PS, ERKQ, if you decide to get them in the next few days, let me know how they look and get some pics.


----------



## erkq




> Quote:
> Originally Posted by *Johnnydc* /forum/post/19980809
> 
> 
> They are by far the cheapest, neatest ones that I have found. So, If I get two sets for each rod, would that do the trick? Also, how about the placement question...hang them with about a foot of wall space showing between each one (mostly to save money)?
> 
> PS, ERKQ, if you decide to get them in the next few days, let me know how they look and get some pics.



I don't think it would "do the trick". If you are using the wrong tool, using 2 wrong tools won't make it work.


I have some more work to do on my sound treatment before I get the coverings so it will be a while. But thanks for the link! I'll have to show it to my girlfriend. It really looks nice.


----------



## systemlayers




> Quote:
> Originally Posted by *systemlayers* /forum/post/19969030
> 
> 
> Hi everyone been reading this thread intently - definitely not ready to pull the gun anytime soon but i've been looking into obtaining some rigid fiberglass in Edmonton Canada.
> 
> I found this large distributer and their rigid fiberglass:
> http://www.crossroadsci.com/PRODUCTS...3/Default.aspx
> 
> It seems to have similar sound coefficients and thickness to the owens corning 703 will this be sufficient or should i search elsewhere/more?



Anyone? Help would really be appreciated


----------



## nathan_h




> Quote:
> Originally Posted by *Johnnydc* /forum/post/0
> 
> 
> They are by far the cheapest, neatest ones that I have found. So, If I get two sets for each rod, would that do the trick? Also, how about the placement question...hang them with about a foot of wall space showing between each one (mostly to save money)?
> 
> PS, ERKQ, if you decide to get them in the next few days, let me know how they look and get some pics.



In case it wasn't clear: these curtains will have no real acoustic benefit. If you place something substantial behind them like thick fiberglass panels of the kind discussed in this thread you'll be on to something. This isn't meant to be rude but just clear.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *systemlayers* /forum/post/19980986
> 
> 
> Anyone? Help would really be appreciated



Looks like they OEM CertainTeed product - they have a line of products actually called "OEM 300" and the like - if it's that, you're good to go. Unfortunately the link to the non-FSK leads to the FSK specs, so can't tell for sure.


----------



## systemlayers




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/19981523
> 
> 
> Looks like they OEM CertainTeed product - they have a line of products actually called "OEM 300" and the like - if it's that, you're good to go. Unfortunately the link to the non-FSK leads to the FSK specs, so can't tell for sure.



Hm yeah they also carry mineral wool products including Roxul AFB.

I know it seems like most in this thread go with fiberglass but rigid mineral wool is just as good correct?

Is it more expensive generally?

Total noobie thanks for the help


----------



## Brad Horstkotte

I used 3" Roxul AFB for my SuperChunks, it was much cheaper locally for me, and has very similar specs to OC 703. Quite easy to work with too, using an electric carving knife.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19924182
> 
> 
> 
> There are a fair number of not so expensive speakers which exhibit excellent sound quality ... Atlantic Technology, Triad are among them.



I called Atlantic Technology and asked for their off-axis test measurements for their flagship fronts. They claimed that they are 'proprietary'. Dennis, I thought that you had once said that any company that does not share these results is the one to avoid (or something similar?).


----------



## Dennis Erskine

Yup...I said that and I'm sticking to that story. On the other hand, I know what it is for their THX stuff. The rest, well ...


----------



## myfipie




> Quote:
> Originally Posted by *systemlayers* /forum/post/19982133
> 
> 
> Hm yeah they also carry mineral wool products including Roxul AFB.
> 
> I know it seems like most in this thread go with fiberglass but rigid mineral wool is just as good correct?
> 
> Is it more expensive generally?
> 
> Total noobie thanks for the help



Mineral wool should be less expensive (density to density comparison). Mineral wool will work fine but keep in mind that you will need to build a frame for the panels as mineral wool is not as rigid as rigid fiberglass. If you are not a master carpenter







then I would stick with the rigid fiberglass. We work with both here so I have first and experience with both.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/19982491
> 
> 
> Yup...I said that and I'm sticking to that story. On the other hand, I know what it is for their THX stuff. The rest, well ...



I am sorry, but I didn't quite understand your response. Are you suggesting that 'Yes, companies who don't reveal their off-axis test data are to be avoided, BUT you still recommend AT because you are very pleased with their THX performance?' Thank you.


----------



## Johnnydc




> Quote:
> Originally Posted by *nathan_h* /forum/post/19981000
> 
> 
> In case it wasn't clear: these curtains will have no real acoustic benefit. If you place something substantial behind them like thick fiberglass panels of the kind discussed in this thread you'll be on to something. This isn't meant to be rude but just clear.



No problem, and I like the feedback. My main goal is not to deaden the sound heard from other parts of the house, but to keep the sound quality in the room at it's best and on a very low budget (wife isn't 100% on board with this yet). I thought the curtains would quiet the inside of the room and stop reflection from the side and rear walls.


----------



## erkq




> Quote:
> Originally Posted by *Johnnydc* /forum/post/19983867
> 
> 
> No problem, and I like the feedback. My main goal is not to deaden the sound heard from other parts of the house, but to keep the sound quality in the room at it's best and on a very low budget (wife isn't 100% on board with this yet). I thought the curtains would quiet the inside of the room and stop reflection from the side and rear walls.



This isn't just the wrong tool from the sound isolation standpoint, it's the wrong tool from the room treatment standpoint too.


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/19977899
> 
> 
> I must compliment you on the wealth of useful information that you have put together and placed on your website.



Thanks very much Jeff.



> Quote:
> Originally Posted by *pauleyc* /forum/post/19978186
> 
> 
> thanks to Ethan - I've been reading a lot on your sight and even checked out a few of your youtube videos. While there is a lot of science behind it .. I get the impression that you can just keep adding with 'minimal' ill effects? (strictly speaking m-ch/HT)??



Not sure what you're asking. Adding _what_ with minimal effects? Bass traps?


--Ethan


----------



## pauleyc




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/19984171
> 
> 
> Not sure what you're asking. Adding _what_ with minimal effects? Bass traps?
> 
> --Ethan



Sorry my question wasn't clear ... I got from one of you videos that most rooms will benefit from absorption and you seem to indicate that you couldn't, under normal circumstances, 'over' do it. My question is more of when would adding more bass traps have a negative effect on a home theater environmnet (multichannel, not 2-ch). I have the ability to "super chunk" all four corners of my HT and wanted to understand if it can be over-done.


----------



## Brad Horstkotte

Chunk em and don't look back.


----------



## nathan_h




> Quote:
> Originally Posted by *Johnnydc* /forum/post/0
> 
> 
> 
> No problem, and I like the feedback. My main goal is not to deaden the sound heard from other parts of the house, but to keep the sound quality in the room at it's best and on a very low budget (wife isn't 100% on board with this yet). I thought the curtains would quiet the inside of the room and stop reflection from the side and rear walls.



Sorry this is what we are saying: curtains won't do that for you. You need something porous but more importantly with considerably more mass.


How "handy" are you? What's your budget? Folks may have suggestions to get you started on effective solutions based on that data.


----------



## nathan_h




> Quote:
> Originally Posted by *pauleyc* /forum/post/0
> 
> 
> 
> Sorry my question wasn't clear ... I got from one of you videos that most rooms will benefit from absorption and you seem to indicate that you couldn't, under normal circumstances, 'over' do it. My question is more of when would adding more bass traps have a negative effect on a home theater environmnet (multichannel, not 2-ch). I have the ability to "super chunk" all four corners of my HT and wanted to understand if it can be over-done.



It is possible to over absorb but what you are proposing is going to be far more beneficial than problematic. You are covering very little wall space but you are making it super thick and putting it where it will have maximum bass impact.


I agree with the advice to do it and don't look back.


----------



## myfipie




> Quote:
> Originally Posted by *pauleyc* /forum/post/19984854
> 
> 
> Sorry my question wasn't clear ... I got from one of you videos that most rooms will benefit from absorption and you seem to indicate that you couldn't, under normal circumstances, 'over' do it. My question is more of when would adding more bass traps have a negative effect on a home theater environmnet (multichannel, not 2-ch). I have the ability to "super chunk" all four corners of my HT and wanted to understand if it can be over-done.



In theory you could over absorb low end but in the real world it is not going to happen. By the time you put traps in every corner (wall to wall, ceiling to wall and floor to wall corners) I still believe the low end would just continue to become better. There is though a point of diminishing returns but that is really dependent on our room. All and all in most smaller rooms, if you cover all wall to wall corners you are not hitting the thresh hold of diminishing returns.


----------



## scoobygt68

I've recently installed some bass traps and acoustic panels and I had a question about speaker placement near acoustic panels/bass traps. My fronts/center have rear ports and are fairly close to the acoustic panels and bass traps. In one corner i have my right speaker only about 10 inches away from the bass traps straddling the corner floor to ceiling. My center is also about 10 inches away from the acoustic panel that is up against the wall between the floor and my projector screen. My question is do i need to move the speakers further away from the treatments since they have rear firing ports?


----------



## nathan_h

No


----------



## NicksHitachi

Ok so I built some bass traps a while ago looking at some of the designs found on here. I think I may have made a mistake, I removed the vapor barriers when I sandwiched them together to get 4".


Ive been reading about poly barriers and backings which I did not know anything about when I made the last design. I plan on redoing them for my current theater build.
I was wondering if I should add some layer of poly or backing back?
Has anyone tried using rigid fiberglass as a backing like VCT tile?

Here are some pics of the old build how could I improve these?


----------



## pepar

Stretch the covering tighter?


----------



## NicksHitachi

Quote:

Originally Posted by *pepar* 
Stretch the covering tighter?
Haha, OK better performance wise. They're going behind a screen wall anyways.


----------



## pepar

Had you ever checked the acoustical properties at http://www.bobgolds.com/AbsorptionCoefficients.htm?


----------



## Brad Horstkotte

Not sure what the batting is for - to support the fiberglass (create airspace behind) and keep fibers in (front)?


As for poly - for what? Kind of lost there. You can put kraft paper (or the faced side of faced fiberglass) on the outside face to reflect highs; but unless your room is already overobsorbed, it might not matter.


----------



## Johnnydc




> Quote:
> Originally Posted by *nathan_h* /forum/post/19987416
> 
> 
> Sorry this is what we are saying: curtains won't do that for you. You need something porous but more importantly with considerably more mass.
> 
> 
> How "handy" are you? What's your budget? Folks may have suggestions to get you started on effective solutions based on that data.



OK, I'm fairly handy but time is a major problem for me right now. Here's a good question:

***IF YOU HAD A NEW THEATER ROOM AND YOU HAD $200-250, HOW WOULD YOU TREAT THE WALLS TO ASSURE YOU GET THE BEST SOUND QUALITY IN THE ROOM?

(6- satellite speakers, 2- 8' powered subs, center channel, 7.2 receiver)


----------



## Brad Horstkotte

I'd either sink it into bass traps - or do nothing until I've listened to it for a while and determined what audio issues need addressing.


----------



## nathan_h

I'm not sure if you can get enough mass for that budget to do much good bass trapping.


So I would attack slap echo, comb filtering, and imaging.


If you have time to build yourself, you could probably put together good bass trapping AND build what I am suggesting you buy, but if you have no time and $200 ish to spend, I'd get:

http://www.gikacoustics.com/gik_242.html 


which come three in a box, and with shipping should be within your budget.


(There are a few other sources for similar panels at a similar price, but I wanted to just cut to the chase with one of the vendors we know is reliable.)


I would place one at the left reflection point and one at the right reflection point (do a search in this thread for "mirror method"). And I would place one on the wall behind my head.



----


If you post a picture or three of your room, and note the dimensions of your room, there may be some more ideas that people have.



----


If you are near a major metropolitan area, watch craigs list and ebay and audiogon for people selling their acoustic treatments. You'll get stuff for half price, easy, if you are patient.


----------



## nathan_h




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/19990212
> 
> 
> Ok so I built some bass traps a while ago looking at some of the designs found on here. I think I may have made a mistake, I removed the vapor barriers when I sandwiched them together to get 4".
> 
> 
> Ive been reading about poly barriers and backings which I did not know anything about when I made the last design. I plan on redoing them for my current theater build.
> I was wondering if I should add some layer of poly or backing back?
> Has anyone tried using rigid fiberglass as a backing like VCT tile?
> 
> Here are some pics of the old build how could I improve these?



Those should be fine as is.


----------



## Dennis Erskine




> Quote:
> I am sorry, but I didn't quite understand your response. Are you suggesting that 'Yes, companies who don't reveal their off-axis test data are to be avoided, BUT you still recommend AT because you are very pleased with their THX performance?' Thank you.



No. Not exactly. There are two issues here. The first is that a company who will not reveal their performance (or cannot because they don't know) is possibly not wanting you to know the performance of the product they are trying to sell. The second is, with AT, and with respect to their THX certified products, they have taken the time, energy and money to have an independent third party test their products, examine the product's engineering, and to make the modifications necessary in order to certify the products meet the established criteria to pass certification and are suitable for their intended purpose. In the case of speakers, there is nothing proprietary with respect to the speaker's response, polar radiation, plots, etc. What could be considered proprietary is how they achieved that performance.


----------



## NicksHitachi




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> 
> Those should be fine as is.



Thanks, I'll probably pretty them up..... Anybody thought of incorporating high density fiberglass(VCt) in the trap for mass?


----------



## pepar

Quote:

Originally Posted by *DIYHomeTheater* 
I am sorry, but I didn't quite understand your response. Are you suggesting that 'Yes, companies who don't reveal their off-axis test data are to be avoided, BUT you still recommend AT because you are very pleased with their THX performance?' Thank you.
THX certification itself says something about the off-axis performance of a speaker.


----------



## Jay5298

I finally started building my bass traps. I bought some 6lb density board from Knauf that I thought was the unfaced insulation, but when I opened the boxes they were the FSK faced board. My thought was to build the front traps without the facing as I don't think I should need that up front. The back traps however I think would benefit from the facing based on my surrounds. I have Paradigm ADP-590's in the back as well as the sides. These speakers fire more laterally than diagonally based on their design. My traps will be in their line of fire so to speak so I think using the FSK on these rear traps would be a good idea. What do you guys think?


----------



## Haps

Sheesh this thread is a monster. I keep coming back to it and working thru more of it and re-reading and "peeling layers of understanding" off that knowledge onion.


13.5x21 room with 10.5 ceilings. From what I've gleaned so far I would benefit from:


1) Corner bass traps. 2 Front corners floor to ceiling. 2 rear corners floor to ceiling. More would be better. Looking for best bang for the DIY buck. If I can find it in Ontario then OC703 4 inch across the corners. Or cut into triangles and stacked in corner frame. Cover with black speaker fabric.


I'm concerned about sourcing the material. Are there other more common alternatives? Is hitting the 4 corners floor to ceiling a good start?


2) Wall treatments. Right now 1st reflection points. 2'x4' covered panel attached to wall. 2 4" thick panels behind back row. Also a(size unknown) panel on ceiling at "mirror test" reflection point.


Am I moving in the right direction? Is this a good start or am I missing the mark?


----------



## kevinzoe

Quote:

Originally Posted by *Haps* 
Sheesh this thread is a monster. I keep coming back to it and working thru more of it and re-reading and "peeling layers of understanding" off that knowledge onion.


13.5x21 room with 10.5 ceilings. From what I've gleaned so far I would benefit from:


1) Corner bass traps. 2 Front corners floor to ceiling. 2 rear corners floor to ceiling. More would be better. Looking for best bang for the DIY buck. If I can find it in Ontario then OC703 4 inch across the corners. Or cut into triangles and stacked in corner frame. Cover with black speaker fabric.


I'm concerned about sourcing the material. Are there other more common alternatives? Is hitting the 4 corners floor to ceiling a good start?


2) Wall treatments. Right now 1st reflection points. 2'x4' covered panel attached to wall. 2 4" thick panels behind back row. Also a(size unknown) panel on ceiling at "mirror test" reflection point.


Am I moving in the right direction? Is this a good start or am I missing the mark?


Hi Haps,

By Ontario, I'm assuming you mean the CDN province. If so, then call General Insulators in Mississauga at (866) 459-1323. They delivered my Owins Corning 701 insulation for my bass traps. OC701 is less costly than 703 and does the same job. It's only at the frequency extremes when there's a performance difference of any real tangible amount.


I would recommend you read Dr Floyd Toole's book and also the textbook by F Alton Everest to educate yourself on what goes where. I would recommend thicker than 4" if you can do it. 4" is the bare minimum and remember to put an ample air space behind the traps to lower the frequency that it'll absorb to.


----------



## Jay5298

Anybody?


----------



## nathan_h




> Quote:
> Originally Posted by *Jay5298* /forum/post/20005791
> 
> 
> Anybody?



Either way is workable and neither would be bad.


----------



## myfipie




> Quote:
> 1) Corner bass traps. 2 Front corners floor to ceiling. 2 rear corners floor to ceiling. More would be better. Looking for best bang for the DIY buck. If I can find it in Ontario then OC703 4 inch across the corners. Or cut into triangles and stacked in corner frame. Cover with black speaker fabric.



I would go with cutting into triangles as this will reach lower frequencies.


----------



## erkq

What about rectangular bass traps? Is there anything inherently superior about the triangular shape except it fits in a corner, that thing most rooms have 4 of? What if I have a 1' deep 6' wide alcove at one side of the back of my theater? Would filling it completely, floor to ceiling, with OC 703 (or 701) be better than a triangular corner trap?


----------



## mtbdudex

Ethan/Glenn/Dennis/Terry/et all experts;


My DIY corner bass traps are in process of being finished.


Simply, what is "appropriate" material to block mid-hi freq on them?

In reality, any material you can't breath thru will work fine for mid-hi freq blockage, is that a correct statement?

I recall some people may have used plastic, so whatever the DIY person has around is ok?


In the below I had this brown utility paper handy so used that, I'll be putting the fabric over them either tonight or Wed night, depends on how much time I have after putting the kids to bed...


thx for your advice. Love this thread.


un-blocked









vs blocked.











Learning Q:

Is that because the mid-hi freq size is larger than the blocking item, in this case a 48" high x 34" wide "wall" ?

So it will "pass" waves greater than 34" (below 400hz-approx) on the width axis and 48" (below 300hz-approx) on the height axis?


----------



## Ethan Winer




> Quote:
> Originally Posted by *Jay5298* /forum/post/20002423
> 
> 
> My traps will be in their line of fire so to speak so I think using the FSK on these rear traps would be a good idea. What do you guys think?



Corner bass traps work best with a facing. Just because sound reaches a trap doesn't mean it's at a reflection point. Reflection points are the only places _not_ to use traps with a facing.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20008425
> 
> 
> what is "appropriate" material to block mid-hi freq on them?



Thin cardboard, thick paper, plastic wrap - it's all good.


--Ethan


----------



## Jay5298




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20008722
> 
> 
> Corner bass traps work best with a facing. Just because sound reaches a trap doesn't mean it's at a reflection point. Reflection points are the only places _not_ to use traps with a facing.
> 
> 
> --Ethan



Ethan,

I peeled the facing off the insulation I'm using in the front, so I could put it back on with spray adhesive I'm assuming? Does it make sense to use the facing on the front traps though? Don't I want to absorb some of the mids and highs from my front speakers? Also, the facing is shiny silver, I'm afraid when I wrap them with GOM it will show, is it okay to spray paint the surface black?


----------



## Jay5298

Maybe I should stop trying to over think all of this and just build the damn bass traps and listen to how it sounds with them in place. What do you guys think about that?


----------



## pepar

You can never be too rich, too thin or have too many corner bass traps.


----------



## erkq




> Quote:
> Originally Posted by *erkq* /forum/post/20008298
> 
> 
> What about rectangular bass traps? Is there anything inherently superior about the triangular shape except it fits in a corner, that thing most rooms have 4 of? What if I have a 1' deep 6' wide alcove at one side of the back of my theater? Would filling it completely, floor to ceiling, with OC 703 (or 701) be better than a triangular corner trap?





> Quote:
> Originally Posted by *pepar* /forum/post/20011175
> 
> 
> You can never be too rich, too thin or have too many corner bass traps.



What about RECTANGULAR bass traps???







Someone's got to know...


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/20011199
> 
> 
> What about RECTANGULAR bass traps???
> 
> 
> 
> 
> 
> 
> 
> Someone's got to know...



I seem to remember reading that the material "beyond" the triangle adds very little performance and would be better deployed as more lineal feet of "single" triangle traps.


----------



## NicksHitachi

How big to make the triangles?


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/20011224
> 
> 
> I seem to remember reading that the material "beyond" the triangle adds very little performance and would be better deployed as more lineal feet of "single" triangle traps.



Thanks! Good to know.


----------



## mtbdudex




> Quote:
> Originally Posted by *Jay5298* /forum/post/20011169
> 
> 
> Maybe I should stop trying to over think all of this and just build the damn bass traps and listen to how it sounds with them in place. What do you guys think about that?



+1 agreed, just buy 2 boxes of 2" 2' x 4' OC705 (6 sheets/box) if you are going 8 feet high with 17x17x24 triangles, or 4 boxes if going for the "biggies" 24 x 24 x 34" triangles.

Measure room (freq wise, freq plot & RT60 baseline), and then...for the OC705 Measure em (dim wise), whack em, stack em, cover em (if you want to block hi freq do so before the cover) then re-measure room with treatments in.


Ready - set - go!


----------



## smokarz

i don't have space for the triangle chunks on my front walls....


what about building 4" thick panel of OC703 and place them in the corner, does that work for bass trapping?


----------



## pepar

How about at the wall/ceiling "corner?"


----------



## pepar




> Quote:
> Originally Posted by *smokarz* /forum/post/20012488
> 
> 
> i don't have space for the triangle chunks on my front walls....
> 
> 
> what about building 4" thick panel of OC703 and place them in the corner, does that work for bass trapping?



A panel "straddling" the corner works.


----------



## Jay5298

Okay, unfortunately I still have one more question. Is it okay to spray paint the FRK foil on the insulation so it doesn't show thru the GOM fabric?


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/20013551
> 
> 
> Okay, unfortuately I still have one more question. Is it okay to spray paint the FRK foil on the insulation so it doesn't show thru the GOM fabric?



I can't see how that would change the acoustical properties of the foil, but what paint is going to adhere to it and not crack over time? That foil will be flexing from the energy that strikes it.


Just throwing that out there ....


Jeff


----------



## Jay5298




> Quote:
> Originally Posted by *pepar* /forum/post/20013568
> 
> 
> I can't see how that would change the acoustical properties of the foil, but what paint is going to adhere to it and not crack over time? That foil will be flexing from the energy that strikes it.
> 
> 
> Just throwing that out there ....
> 
> 
> Jeff



Good point. I guess I will see if the GOM shows thru first and go from there.

Thanks


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/20012781
> 
> 
> How about at the wall/ceiling "corner?"





> Quote:
> Originally Posted by *pepar* /forum/post/20012786
> 
> 
> A panel "straddling" the corner works.



thanks, i was thinking of 2 24"x48" OC703 4" thick panels at the front corners (bottom)


and 2 24"x24" 2" OC703 on the top corners.


----------



## NicksHitachi

Which would be the better performer?


4" OC703 2'x4' panel straddling corner


or


12"X12"X24" superchunks approx 64" tall(coverage from two 2"OC703 panels cut up into super chunks)


----------



## Jay5298

Well, the foil shows thru. I sprayed a section and it doesn't adhere very well. What about flipping the foil over so the plain side is up? Any problem doing this? I may just scratch the whole FRK facing and go without if it's to much of a pain.


----------



## nathan_h

Flipping the foil is fine as long as it still is on the outside (not against the wall).


----------



## pepar

Quote:

Originally Posted by *NicksHitachi* 
Which would be the better performer?


4" OC703 2'x4' panel straddling corner


or


12"X12"X24" superchunks approx 64" tall(coverage from two 2"OC703 panels cut up into super chunks)
There's some test data on the StudioTips Forum, but it seems to be down right now. (You probably mean 17x17x24 as that is the result of cutting a 2' x 4' panel into eight triangles.) I seem to remember the chunk outperforming the panel . ... but that might have been the 34" face triangle resulting from cutting the 2' x 4' panel into FOUR triangles. Keep checking back at http://www.forum.studiotips.com .


Jeff


----------



## Jay5298

Quote:

Originally Posted by *nathan_h* 
Flipping the foil is fine as long as it still is on the outside (not against the wall).
Cool, Thanks.


----------



## NicksHitachi

Quote:

Originally Posted by *pepar* 
There's some test data on the StudioTips Forum, but it seems to be down right now. (You probably mean 17x17x24 as that is the result of cutting a 2' x 4' panel into eight triangles.) I seem to remember the chunk outperforming the panel . ... but that might have been the 34" face triangle resulting from cutting the 2' x 4' panel into FOUR triangles. Keep checking back at http://www.forum.studiotips.com .


Jeff
OK, I gather then that cutting the 2x4 panel into 16 1x1x2 triangles would be inferior..... Right? Cutting in this fashion would yield approx the same vertical corner coverage as two 2" 2x4 panels straddling the corner, which is why I'm comparing the smaller triangles and smaller super chunks.....


----------



## smokarz




> Quote:
> Originally Posted by *pepar* /forum/post/20014469
> 
> 
> There's some test data on the StudioTips Forum, but it seems to be down right now. (You probably mean 17x17x24 as that is the result of cutting a 2' x 4' panel into eight triangles.) I seem to remember the chunk outperforming the panel . ... but that might have been the 34" face triangle resulting from cutting the 2' x 4' panel into FOUR triangles. Keep checking back at http://www.forum.studiotips.com .
> 
> 
> Jeff



i am very interested in this data.


4" 2'x4' panel *OR* 17"x17"x24" superchunks


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/20014930
> 
> 
> OK, I gather then that cutting the 2x4 panel into 16 1x1x2 triangles would be inferior..... Right?



Cutting a 24" x 48" sheet into sixteen triangles would yield 12" x 12" x 17" triangles.


I didn't even stay at a Holiday Inn Express last night, but my *guess* is that the straddling 2' x 4' panel would be more effective than the 16-triangle size from the same sheet. You really need to do the 8-triangle cut to get deeper absorption.


Unless you don't have the _space_, you need to bite the bullet and use the 8-cut size. As a DIY project, these are still way more economical than commercial products.


If I would have had the space, I would have used the 4-cut size.


Jeff


----------



## NicksHitachi




> Quote:
> Originally Posted by *pepar* /forum/post/20015236
> 
> 
> Cutting a 24" x 48" sheet into sixteen triangles would yield 12" x 12" x 17" triangles.
> 
> 
> I didn't even stay at a Holiday Inn Express last night, but my *guess* is that the straddling 2' x 4' panel would be more effective than the 16-triangle size from the same sheet. You really need to do the 8-triangle cut to get deeper absorption.
> 
> 
> Unless you don't have the _space_, you need to bite the bullet and use the 8-cut size. As a DIY project, these are still way more economical than commercial products.
> 
> 
> If I would have had the space, I would have used the 4-cut size.
> 
> 
> Jeff



DUH! yeah I was not thinking A2+B2=C2. I'm gonna dig a bit more to see if there has been some direct comparisons made. Like you however I think the panel would probably perform better. I think i read somewhere that the incremental increase in performance went down after about 4" thickness and therefore the loss in coverage(width) in the corner would not be compensated for with increasing the depth.


Thanks for the response!


----------



## smokarz

ok guys,


i finally put up twelve 24"x48" panels in a 13'x24' room. is this too much?


i got 4 on the right wall, 5 on the left wall, and 3 in the back wall.....


nothing on front wall or ceiling yet.


----------



## Brad Horstkotte

Also, if budget is more of a constraint than space, you may be able to locate alternatives to OC 703 that are available locally cheaper, and work just as well. In my case, I used Roxul AFB, and the cost was about half what it would have cost for OC 703.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *nathan_h* /forum/post/20014238
> 
> 
> Flipping the foil is fine as long as it still is on the outside (not against the wall).



Or leave the FRK in place, and add a thin layer of something over it. I was thinking black plastic, but not sure about the flammability, maybe there's something better and cheap. Black polyethylene sheeting?


I'm in the same boat BTW, I have FRK side of rigid insulation facing down in my soffit, and will have to address the same issue as you when I get to covering it with fabric.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *smokarz* /forum/post/20016179
> 
> 
> ok guys,
> 
> 
> i finally put up twelve 24"x48" panels in a 13'x24' room. is this too much?
> 
> 
> i got 4 on the right wall, 5 on the left wall, and 3 in the back wall.....
> 
> 
> nothing on front wall or ceiling yet.



Only way to tell for sure would be to measure.


I ran Bob Gold's room mode calculator, thinking that a ballpark number of required Sabins (unit of absorption) could help you - but really it doesn't, since you don't know how many Sabins you're starting with (carpet, furniture, humans all absorb). Well anyway, assuming 8' ceiling height, it said 549 Sabins required to achieve RT60. For reference, 12 2'x4' panels is 96 square feet, if they were 100% absorptive, that would be 96 Sabins. So unless you've got a ton of squishy furniture and people in the room, I think you're probably fine. You've covered 96 square feet of a possible 592 square feet of wall space, only about 16%. Many HTs cover ~50%.


Someone check my math...


----------



## KERMIE

Ethan,


I have a question regarding your test tone files I downloaded.


I set my crossovers on my AVR to 80Hz for my L/C/R speakers, Sides and Rears for 7.1.


For some strange reason the test tones below that crossover plays on my Center Channel loud down to 20 Hz with little regards to my Crossover. All other speakers start dropping off nicely and disappear as I go below 60-65 hz. I am concerned that for movies that my crossover is not working and LF is going to ruin my center channel.


Is anyone experiencing this or doest the "Center Channel" just react differently?


Thanks in advance for any assistance.


----------



## Brad Horstkotte

Maybe your center is set to "large", and the rest are set to small?


----------



## KERMIE

Its an Integra 70.1 and it doesn't have that option. There is only crossover points for each. I double checked and it is crossed over at 80 like all the other 6 speakers. When I turn off my subs and run 20-60 Hz test tones the sound comes out of center and not any other speaker. Very strange to me


----------



## Brad Horstkotte

I guess with that receiver, it would be under Speaker Configuration -> Full Band - just in case you didn't check there


----------



## Jay5298




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20016410
> 
> 
> Or leave the FRK in place, and add a thin layer of something over it. I was thinking black plastic, but not sure about the flammability, maybe there's something better and cheap. Black polyethylene sheeting?
> 
> 
> I'm in the same boat BTW, I have FRK side of rigid insulation facing down in my soffit, and will have to address the same issue as you when I get to covering it with fabric.



Brad,

I peeled the FRK foil off the insulation and then flipped it over and re-attached it with spray adhesive. Worked great, and now it doesn't show thru the GOM.


----------



## Jay5298

Okay, once again I'm over thinking things as I always do. I built one corner bass trap. I used 2 pieces of 705 stacked to make a 4" thick panel and then cut the ends at a 45 degree angle so they would fit flush in the corner. I then built a frame from floor to soffit filled it with the insulation and hung it up. Looks great but now I'm wondering if there is a performance difference between this design and a typical rectangle trap straddling the corner. I attached a drawing of what I'm talking about. Technically when you look at the drawing the 24" in the rectangle trap is from corner to corner. The trapezoid design the 24" is from corner to corner also, but the back of the panel surface area is less, I think mine was about 15". So the air gap from the back of the rectangle trap is deeper than the trapezoid design. The trapezoid design is sort of like the superchunk style(although not as deep)and the rectangle style. I think it should perform similar to the rectangle design, I just have my doubts now. Why can't I just do something without second guessing myself all the time


----------



## Brad Horstkotte

Shouldn't be significantly different - you could get a little more by stuffing the cavity behind with fluffy insulation (heard that one from bpape way back somewhere in this thread).


Edit: my mistake, it wasn't actually bpape, it was TamaraBaap - but it sounded logical to me: http://www.avsforum.com/avs-vb/showt...56#post8119356


----------



## erkq




> Quote:
> Originally Posted by *KERMIE* /forum/post/20019469
> 
> 
> Its an Integra 70.1 and it doesn't have that option. There is only crossover points for each. I double checked and it is crossed over at 80 like all the other 6 speakers. When I turn off my subs and run 20-60 Hz test tones the sound comes out of center and not any other speaker. Very strange to me



As a work-around to protect your speaker for the short term, you could put a big capacitor in series and an inductor in parallel. Values depend on your speaker's impedance. There are lots of on-line calculators for this. That would get you a 12dB/octave roll-off. It would also introduce insertion loss and phase shift like any other simple filter, but at least it would protect against over-excursion while you figure out how to fix it for real.


----------



## mtbdudex

Quote:

Originally Posted by *Jay5298* 
Okay, once again I'm over thinking things as I always do.
Jay - I do it also many times, that's good - up to a point.


I'm sure you've seen Ethan W page?
http://www.ethanwiner.com/acoustics.html#air%20gap 

The % diff in gap to wall is so small either way, whatever works....

Picts from that page:


















So, what's the difference in gap to wall and from this chart how much freq did you "miss" covering?










did you take before/after measurements?


----------



## Jay5298

Quote:

Originally Posted by *mtbdudex* 
Jay - I do it also many times, that's good - up to a point.


I'm sure you've seen Ethan W page?
http://www.ethanwiner.com/acoustics.html#air%20gap 

The % diff in gap to wall is so small either way, whatever works....

Picts from that page:


















So, what's the difference in gap to wall and from this chart how much freq did you "miss" covering?










did you take before/after measurements?
I did not take any measurements, I don't have a laptop computer. I guess I will just let my ears be the judge.


----------



## mtbdudex

Quote:

Originally Posted by *Jay5298* 
I did not take any measurements, I don't have a laptop computer. I guess I will just let my ears be the judge.
Honestly I could immediately notice the side wall panels and their 1st reflection effect when I put those up.

The bass traps are noticable vs w/o, but also more subtle, guess it all depends on your room issue(s) and qty of bass traps/etc, size, etc.

(plus I have the riser bass trap already and the ceiling cloud which is 12" suspended and helping bass somewhat, so I've had incremental treatments added prior to my corner traps, therefore mine is not a true "no bass trap" vs "bass trap" comparision)


----------



## Ethan Winer

Quote:

Originally Posted by *KERMIE* 
For some strange reason the test tones below that crossover plays on my Center Channel loud down to 20 Hz with little regards to my Crossover.
Others already gave you the right answer - it's most likely a receiver setting.


--Ethan


----------



## dallaslistener

OK Guys,


I've set up all the recommended equipment and I'm using REW and getting an error message which I don't understand - "impulse peak is not where it should be, the measurement may have been corrupted". What do I do now? Also, the spl graph dips way down below the -60db limit at 2khz and up. Any body know what's wrong?


----------



## mtbdudex

Ethan/Terry/Dennis;


Have you guys used this product , ECOUSTIMAC Eco Friendly DIY Insulation (4 lbs/ft) 48"x24"x2" , as alternative to OC705 for Bass traps?


It came up in my DIY panel build thread, http://www.avsforum.com/avs-vb/showt...0#post20037070 


I'm ready to buy 3 cases of the 2" 2' x 4' sheet, but want to know if you've used it prior and feedback if any.


I called their tech support and asked who their 3rd party test company is, he said http://riverbank.alionscience.com/ 


Seems like a legit product.


Copy and past from the DIY panel build thread:


> Quote:
> Well looking at the data it sure seems to have much better low freq absorption characteristics....
> http://www.acoustimac.com/index.php/...oinsul422.html
> 
> 
> 
> Quote:
> 
> 
> 
> Quote:
> Sound Absorption Coefficients (1/3 Octave Band Center Frequencies. HZ)
> 
> 
> Hz
> 
> 100 125 250 500 1000 2000 4000
> 
> 2" Thickness 0.38 .39 .63 1.18 1.11 1.06 1.09
> 
> 
> An even greener alternative to cotton insulation:
> 
> 
> Cotton insulation works as well as its fiberglass counterparts, however this material can be prone to mold and is not as biodegradable and recyclable as cellulose which is made from recycled newspapers and cardboard products.
> 
> 
> Better Performance than Fiberglass!
> 
> 
> Oh yes, it's true! This cellulose based insulation has even higher absorption coefficients than our standard insulation material, so not only is it more eco-friendly, it also outperforms its fiberglass and mineral wool counterparts hands down.
> 
> 
> 
> 
> 
> 
> 
> Quote:
> Freq 125 HZ 250 HZ 500 HZ 1000 HZ 2000 HZ 4000 HZ NRC
> 
> OC-703 (2") 0.17 0.86 1.14 1.07 1.02 0.98 1.00
> 
> Click to expand...
> 
> 
> 
> 
> 
> Quote:
> Freq 125 HZ 250 HZ 500 HZ 1000 HZ 2000 HZ 4000 HZ NRC
> 
> OC-705 0.16 0.71 1.02 1.01 0.99 0.99 0.95
> 
> Click to expand...
> 
> 
> 
> Click to expand...
> 
> 
> and when you compare the online price of 705 to this ....so you get your cake (better low freq absorption) and get to eat it too (lower cost/6 pcs).....I need more 705, now I'll re-think that and consider this.
> 
> Thx for posting!
> 
> (Bruce - let me know what they say about cutting it, if a serrated bread knife does it same as thru OC703/705 that would be nice.)
> 
> 
> For their ECOUSTIMAC line, has there been 3rd party testing to confirm their claims?
> 
> I'd hate to be 1st on the block in avs community to use them.....I wonder if Ethan W/Dennis E/others have used their product.....
Click to expand...


----------



## NicksHitachi




> Quote:
> Originally Posted by *mtbdudex* /forum/post/0
> 
> 
> Ethan/Terry/Dennis;
> 
> 
> Have you guys used this product , ECOUSTIMAC Eco Friendly DIY Insulation (4 lbs/ft) 48"x24"x2" , as alternative to OC705 for Bass traps?
> 
> 
> It came up in my DIY panel build thread, http://www.avsforum.com/avs-vb/showt...0#post20037070
> 
> 
> I'm ready to buy 3 cases of the 2" 2' x 4' sheet, but want to know if you've used it prior and feedback if any.
> 
> 
> I called their tech support and asked who their 3rd party test company is, he said http://riverbank.alionscience.com/
> 
> 
> Seems like a legit product.
> 
> 
> Copy and past from the DIY panel build thread:



If you average the 1st three absorption coefficients you'll see the fiberglass is still the better absorber overall. Sure it looks like it does more at 125 but compare their respective progressive absorbances........


----------



## Dennis Erskine

Riverbank .... excellent lab.


This can be used for your bass trap (don't know how you intend to fabricate, where it will be placed). As a single layer, not much of a trap at all. This stuff could over absorb your high frequencies so you'd want to put 3 mil poly sheeting over the top of the first layer.


----------



## mtbdudex




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/20040191
> 
> 
> If you average the 1st three absorption coefficients you'll see the fiberglass is still the better absorber overall. Sure it looks like it does more at 125 but compare their respective progressive absorbances........



I'll be using this as a Bass trap, so I'm more concerned with the 100hz, 125hz performance, even the 250hz perf is very close.





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20040321
> 
> 
> Riverbank .... excellent lab.
> 
> 
> This can be used for your bass trap (don't know how you intend to fabricate, where it will be placed). As a single layer, not much of a trap at all. This stuff could over absorb your high frequencies so you'd want to put 3 mil poly sheeting over the top of the first layer.



Dennis;

I used OC705 24"x24"x34" superchunk stack 4' high floor-to-mid room on both rear corners of my HT, as currently done, they have kraft paper in front to block mid-hi freq, I plan on doing that for the upper ones also.











My next step in bass traps is this ECOUSTIMAC Eco Friendly Insulation will be in a 24"x24"x34" trapezoid shaped to a 17" x 17" x 24" superchunk stack ceiling down 2'.


With this products performance "superior" to OC705 in the low freq region, what advantage is there in using OC705 for a bass trap?

(except possible you can get OC705 locally for lower cost)

Pict show the image:


> Quote:
> Plan B:
> 
> I'll call this the "Trapezoid wedgie bass trap", consists of smaller triangles 17" x 17" x 24" blending into the biggie 24" x 24" x 34" to get more low freq absorption.
> 
> The thd rod will be hidden inside the bass trap except will show on the bottom.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm 90% going with Plan B, I think it will look nicer up there and the hidden rods is better for the upper location.
> 
> Unless I move those sconces full 24" x 24" x 34" size won't fit.
> 
> 
> btw, not all the Star Trek stuff will stay there, it will be de-cluttered, just showing my kids some of the stuff I had back in the day.
> 
> And YES, those Star Wars glasses are original Burger King glasses from the early 1980's, and those are genuine Apollo 13 glasses as well.


----------



## Jay5298

Well I've pretty much given up on the professional companies giving me any help. Sorry if I'm offending anyone. I submitted my pics and dimensions to 2 companies. One never responded with any information and the other is too busy with a high end client to help me. I called another local company, we played phone tag for a while and then nothing.







So I guess I'm on my own. I have almost completed my corner bass traps, just one more to build. I read some but not all of F. Alton Everest's Master Handbook of Acoustics. Some stuff I understood and some was just too technical. He talks about controling the early reflections form the floor and ceiling first and then deciding what to do with the lateral or wall reflections last. Explaining that the direct sound from the speakers arrives first then the floor then the ceiling and then the lateral or wall reflections next, as well as other reflections. I now understand why it was said that I would lose all the envelopment in the room if I covered the side walls with too much absorbtion. You still need to have some sense of spaciousness to the room. I forgot I have an old PC in my basement that I could use to take some measurements. So the question is, if I didn't want to hook up the computer, buy the mics and other stuff to take the measurements. Is the approach of treating the floor(I already have carpet) then the ceiling and then deciding what to do with the walls a good start?


----------



## Brad Horstkotte

I would think whether ceiling or side walls are the priority would depend on speaker location (which is closer) and dispersion (how much energy is fired horizontally and vertically. Personally, I'm not prioritizing the ceiling at least initially - mainly because it's a hassle.


----------



## pepar

FWIW, the absorber that made the biggest difference in my room was the one on the rear wall. Context .. 21' long, rear (and main) row of seats is ~7' from the rear wall making the first reflection about 14ms delayed from the direct sound.


----------



## Jay5298




> Quote:
> Originally Posted by *pepar* /forum/post/20043874
> 
> 
> FWIW, the absorber that made the biggest difference in my room was the one on the rear wall. Context .. 21' long, rear (and main) row of seats is ~7' from the rear wall making the first reflection about 14ms delayed from the direct sound.



I think my room would benefit from some rear absorption as well. When I sit in the middle 2 seats in the front row the bass sounds good. The seats directly behind sound boomy. The seats on either side don't sound as bad I think because of the columns which are made of wood and have insulation inside them. What type of insulation and how thick are your rear absobers?


----------



## Jay5298




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20042982
> 
> 
> I would think whether ceiling or side walls are the priority would depend on speaker location (which is closer) and dispersion (how much energy is fired horizontally and vertically. Personally, I'm not prioritizing the ceiling at least initially - mainly because it's a hassle.



My main speakers are only about 2 feet from the side walls so I probably hear those reflections first I would think. Your right I really don't want to put anything on my ceiling either if I don't have to. The question is how thick should the panels be on the side walls, so I still get some sense of spaciousness.


----------



## Dennis Erskine

You're not going to get "spaciousness" by putting absorption all over (particularily at the early reflection locations). Diffusers or Ab-fusors would be better.


For the speakers being less than 3.5' away from wall, you need some serious absorption near the speaker itself...the effect is called SBIR or Speaker Boundary Interference Response.


----------



## pepar




> Quote:
> Originally Posted by *Jay5298* /forum/post/20047334
> 
> 
> I think my room would benefit from some rear absorption as well. When I sit in the middle 2 seats in the front row the bass sounds good. The seats directly behind sound boomy. The seats on either side don't sound as bad I think because of the columns which are made of wood and have insulation inside them. What type of insulation and how thick are your rear absobers?



2" of Owens Corning SelectSound Black. It is sized to only catch the first reflections from LCR. The rest of the rear wall is plaster.


----------



## Jay5298




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20047472
> 
> 
> You're not going to get "spaciousness" by putting absorption all over (particularily at the early reflection locations). Diffusers or Ab-fusors would be better.
> 
> 
> For the speakers being less than 3.5' away from wall, you need some serious absorption near the speaker itself...the effect is called SBIR or Speaker Boundary Interference Response.



Dennis, I appreciate you giving me the name of the company out here in Colorado. He just apparently doesn't have time right now. You say serious absorption. Are you talking behind the speaker for the cabinet reflection on the front wall, or the side wall as well. My bass traps are pretty close to front speakers so they should absorb some of the reflections. I want to find the "happy medium" if possible to absorb the reflections but not make it too dead sounding. I have read briefly about SBIR, but not too much.


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20047472
> 
> 
> You're not going to get "spaciousness" by putting absorption all over (particularily at the early reflection locations). Diffusers or Ab-fusors would be better.
> 
> 
> For the speakers being less than 3.5' away from wall, you need some serious absorption near the speaker itself...the effect is called SBIR or Speaker Boundary Interference Response.



Instead of absorption, one could use diffusion instead, right? (I think that's what the first half of your response means.)


Or are you saying that at that short distance diffusion isn't an option, but one really has to use absorption (and it should be thicker than one might usually select)?


----------



## Jay5298

Looking at the picture of the front of my room I think the only place I'm going to be able to absorb the reflections from SBIR are on the side walls. My bass traps almost come to the edge of the screen about 6 inches away I think. So they should help somewhat.


----------



## NicksHitachi




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> You're not going to get "spaciousness" by putting absorption all over (particularily at the early reflection locations). Diffusers or Ab-fusors would be better.
> 
> 
> For the speakers being less than 3.5' away from wall, you need some serious absorption near the speaker itself...the effect is called SBIR or Speaker Boundary Interference Response.



Interesting, I always thought most rooms needed absorption at the early reflection points and that it was hard to over absorb unless you got crazy with it..... Hmmmmmm.


So what's wrong with these statements?


1. Front wall should be dead

2. Bass trap as many "corners" as is practical

3. Absorption at primary reflection points

4. Absorption behind all point sources


These were the take home messages I had gleaned, are they incorrect?


----------



## Kal Rubinson

It is easy to over-absorb the treble in the effort to use a sufficient amount of bass trapping since passive absorbtion is generally much more efficient as the frequency rises. Thus, if you are going to use a *lot* of bass trapping, consider using traps with reflective skins for some proportion of them.


----------



## NicksHitachi

Anyone know of a "rule of thumb" as to what the proportion of absorptive area to reflective area might get one in the ball park?


In other words it would be most helpful to get in the ballpark with some "general" proportion and fine tune each space from there. There must be a good starting ratio, although not golden or absolute for each room, which would I think be helpful in this thread.


----------



## FOH

The attached pic in post #7171 doesn't appear to be on the verge of overly damped. IMO, the room would likely benefit from sidewall reflection points being attenuated as much as possible. A nice, simple 4"-6" absorber spaced somewhat off the wall would certainly address potential destructive interference, if care was taken with placement.


If there is only one row of seating, it's likely that one or two panels per side would cover it.




Good luck


----------



## nathan_h




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/20049324
> 
> 
> Interesting, I always thought most rooms needed absorption at the early reflection points and that it was hard to over absorb unless you got crazy with it..... Hmmmmmm.
> 
> 
> So what's wrong with these statements?
> 
> 
> 1. Front wall should be dead
> 
> 2. Bass trap as many "corners" as is practical
> 
> 3. Absorption at primary reflection points
> 
> 4. Absorption behind all point sources
> 
> 
> These were the take home messages I had gleaned, are they incorrect?



1) Not the whole thing. Concentrate on reflection points.

2) Yes. Note: the caveat to cover with a thin layer of plastic sheeting (or paper or foil) is a good one to avoid over absorbing/damping the room.

3) Yes.

4) Probably not necessary, maybe overdoing it.


---


I do still wonder whether Dennis meant that diffusion should not be used on a wall close to a speaker, or whether I was misreading his post.


----------



## FOH




> Quote:
> Interesting, I always thought most rooms needed absorption at the early reflection points



Absolutely


Beginning with diffractive elements at the speaker, continuing to the earliest reflection points at the adjacent surfaces.




> Quote:
> So what's wrong with these statements?
> 
> 
> 1. Front wall should be dead
> 
> 2. Bass trap as many "corners" as is practical
> 
> 3. Absorption at primary reflection points
> 
> 4. Absorption behind all point sources



In my experience, front wall treatment should depend on the room balance.


Bass trapping can be extensive, however, balance can be maintained with FRK, or similar covering if needed. Besides, traps are somewhat more effective when employed with some type of paper or plastic covering. Also, they're best when spaced at 1/4 wavelength from the surface.


In my experience, absorption at the early reflection points is very important. If these points are left untreated, imaging suffers, smearing of transients results, and undesirable destructive coloration occurs. It is true that lateral diffusion results in spaciousness, and this can be maintained, but not at the expense of the earliest first reflections. Additionally, ceilings can be treated aggressively with absorption. We're overwhelmingly more suited to delineate lateral energy, and ceiling reflectivity does little but be destructive between the speakers and listener.


Also, back wall treatments can certainly vary, depending on proximity to the listeners. The closer the wall, generally absorption treatments would be the route. Further away, a nice diffuse mix, with some serious bass trap elements would generally be effective.




Additionally, I'd stay away from "flavor of the month" trends that seem to be so prevalent these days. Watch the RT 60, and move slowly and deliberately with each treatment, be it diffusion, absorption, or whatever. Be mindful that LCR mains, and their respective directivity need to be given strong consideration, and any treatment after the earliest lateral reflections are damped, needs to be done in concert with the mains polar pattern, and the LP.



Just my 2 cents










Listen, measure, experiment, listen


----------



## NicksHitachi




> Quote:
> Originally Posted by *nathan_h* /forum/post/20049946
> 
> 
> 1) Not the whole thing. Concentrate on reflection points.
> 
> 2) Yes. Note: the caveat to cover with a thin layer of plastic sheeting (or paper or foil) is a good one to avoid over absorbing/damping the room.
> 
> 3) Yes.
> 
> 4) Probably not necessary, maybe overdoing it.
> 
> 
> ---
> 
> 
> I do still wonder whether Dennis meant that diffusion should not be used on a wall close to a speaker, or whether I was misreading his post.



I took it to mean that for speakers that close to a boundary, diffusion would not be as effective....... I think for diffusion to work it has to be sufficiently distant to the point source..... Right?


----------



## FOH

Diffusion works regardless how close. However, in my experience, in this situation it's important to have absorption in that location.


----------



## nathan_h




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/20050145
> 
> 
> I took it to mean that for speakers that close to a boundary, diffusion would not be as effective....... I think for diffusion to work it has to be sufficiently distant to the point source..... Right?





> Quote:
> Originally Posted by *FOH* /forum/post/20050178
> 
> 
> Diffusion works regardless how close. However, in my experience, in this situation it's important to have absorption in that location.



This is why I hope Dennis clarifies his comment(s), since two people can look at those comments, filter through their experience, and reach different conclusions.


----------



## mtbdudex




> Quote:
> Originally Posted by *FOH* /forum/post/20050143
> 
> 
> Listen, measure, experiment, listen



great "_sound_" advice.










I'd modify slightly:


Initially (n=0):

Plan(n=n+1), listenBaseline (n=n+1), measureBaseline (n=n+1), experiment [add treatment(s)] (n=n+1), listenChange (n=n+1), measureChange (n=n+1)


Repeat cycle until:

-your $$'s run out

-your time limit is reached

-your brain gets tired

-the WAF is way past

-your non-HT friends stop calling you

-your kids forget your name

-n = 10, unless you have OCD and then the skies the limit


Heck, you might even reach acoustic nirviana and accept that fact and move onto other things......


----------



## FOH




> Quote:
> Originally Posted by *nathan_h* /forum/post/20050359
> 
> 
> This is why I hope Dennis clarifies his comment(s), since two people can look at those comments, filter through their experience, and reach different conclusions.



Generally, a proper diffuser's effectiveness is a function of the frequencies involved, not distance.


Now relative size, that metric must include distance. A 4'x4' diffuser immediately adjacent to someone playing violin, has a different impact than the same person playing violin and the diffuser 20' away. The relative size is different.


Ethan demonstrates a diffuser's properties adjacent to the diffuser. The diffuser is just as effective of a diffuser when it's 20' away, it's still a good diffuser, but the relative size due to proximity changes.


So a bigger room needs more diffuser panels than a small room, however they're no less effective a diffuser.


----------



## Ethan Winer

^^^ Good explanation.


--Ethan


----------



## Dennis Erskine




> Quote:
> This is why I hope Dennis clarifies his comment(s), since two people can look at those comments, filter through their experience, and reach different conclusions.



What comments?


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> 
> What comments?





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20047472
> 
> 
> You're not going to get "spaciousness" by putting absorption all over (particularily at the early reflection locations). Diffusers or Ab-fusors would be better.
> 
> 
> For the speakers being less than 3.5' away from wall, you need some serious absorption near the speaker itself...the effect is called SBIR or Speaker Boundary Interference Response.



Instead of absorption, one could use diffusion instead, right? (I think that's what the first half of your response means.)


Or are you saying that at that short distance diffusion isn't an option, but one really has to use absorption (and it should be thicker than one might usually select)?


----------



## Milt99

Just an FYI,

All of the links to the studiotips website are pau.

The links to the forum within the website itself are dead as well.


----------



## rgoolio32

Hey Im building a HT in my basement and I am newbie at acoustical treatments I have read over the countless literature regarding treatments and understand the basics. But as always I think other opnions would be helpful.


(Ceilings are 7.6 feet)


Attached is a schematic of my HT


I was wondering where I should place panels (OC 703 with GOM Fabric) since it is a 7.1 I will have reflection on the front back and side walls. Also the back speakers are off center to the screen due to the weird shape of the room, and are centered on the back wall.


do you guys have any suggestion? full wall panels? half panels? where you think I should place them?


-RG


----------



## Dennis Erskine

Quote:

Or are you saying that at that short distance diffusion isn't an option, but one really has to use absorption (and it should be thicker than one might usually select)?
No, for that specific issue, there are two problems. The first is the SBIR due to the speakers' proximity to the walls. That issue is best solved by absorption. The second issue is spaciousness which is better solved with diffusion or a combination of diffusion and absorption.


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> No, for that specific issue, there are two problems. The first is the SBIR due to the speakers' proximity to the walls. That issue is best solved by absorption. The second issue is spaciousness which is better solved with diffusion or a combination of diffusion and absorption.



Interesting. I thought SBIR happens in all rooms and that it's a matter of speaker placement (different distances from front and side walls, for example) that solves it.


I guess in the OP's situation (and many domestic rooms) the solution might be absorption behind the speaker on the screen wall and diffusion at the lateral first reflection points.


----------



## dunkman23

hey guys. I was thinking about getting 2 24x48x4 panels from ATS acoustics. However what I am trying to do is dampening the noise of my system. My HT room is towards to front of my house, and people can hear the subwoofer from the driveway. If i put 2 panels in the back of the room, will it quiet down my room from the outside? as well as improve the sound? my room is 20 x 16 with 9 feet ceilings


----------



## Brad Horstkotte

Nope - sound treatments address the character of the sound in the room, but do nothing to affect sound transmission between the room and outside the room.


----------



## nathan_h




> Quote:
> Originally Posted by *dunkman23* /forum/post/0
> 
> 
> hey guys. I was thinking about getting 2 24x48x4 panels from ATS acoustics. However what I am trying to do is dampening the noise of my system. My HT room is towards to front of my house, and people can hear the subwoofer from the driveway. If i put 2 panels in the back of the room, will it quiet down my room from the outside? as well as improve the sound? my room is 20 x 16 with 9 feet ceilings



As noted above, those panels won't help.


But there is a small possibility that an isolation riser like an Auralex Gramma may help a bit. It's not going to silence things but depending on why one can hear the sub outside, it may reduce that. It's the $50 experiment I would recommend.


Otherwise you're probably looking at a construction project of significant proportions (adding mass and or decoupling walls, floor, ceiling; replacing windows and doors; etc.).


----------



## dunkman23

^ ok thanks......those ideas help!


im going to put a post up and see if i get more ideas.


----------



## erkq




> Quote:
> Originally Posted by *nathan_h* /forum/post/20061073
> 
> 
> Otherwise you're probably looking at a construction project of significant proportions (adding mass and or decoupling walls, floor, ceiling; replacing windows and doors; etc.).



Coupled with a Green Glue sandwich. GG works well at lower frequencies. You can usually forgo added mass (except for the additional sheet of drywall) and decoupling.


----------



## nathan_h




> Quote:
> Originally Posted by *erkq* /forum/post/20061254
> 
> 
> Coupled with a Green Glue sandwich. GG works well at lower frequencies. You can usually forgo added mass (except for the additional sheet of drywall) and decoupling.



Very true, unless the sound path is that the sub is rattling the floor and that is what is transmitting the sound that the OP is hearing outside.


----------



## erkq




> Quote:
> Originally Posted by *nathan_h* /forum/post/20061536
> 
> 
> Very true, unless the sound path is that the sub is rattling the floor and that is what is transmitting the sound that the OP is hearing outside.



I've been curious about this. Can you put GG between two layers of subfloor? Or, does GG HAVE to go between something with a smoother surface like drywall?


----------



## nathan_h

Their web site has more info that I have digested, but I could see that possibly working, if one was ready to "rebuild" the floor.


Still I think that, short of a construction project, the thing to try is the $50 isolator and see if that helps enough.


----------



## dm




> Quote:
> Originally Posted by *erkq* /forum/post/20061599
> 
> 
> I've been curious about this. Can you put GG between two layers of subfloor? Or, does GG HAVE to go between something with a smoother surface like drywall?





I have had really good luck with GG between two layers of a subfloor under my hardwood floors.


Read about my experience here:

http://www.avsforum.com/avs-vb/showthread.php?t=1136101


----------



## erkq




> Quote:
> Originally Posted by *dm* /forum/post/20064711
> 
> 
> I have had really good luck with GG between two layers of a subfloor under my hardwood floors.
> 
> 
> Read about my experience here:
> 
> http://www.avsforum.com/avs-vb/showthread.php?t=1136101



Thanks! GG acting as a bass trap makes total sense.


----------



## Tireman1

Ethan,


Have the 705 foil out in some areas. Would a light dusting of flat spray paint cause any problems? The reflection shows through the GOM 701 at some angles.


Thanks,


----------



## nathan_h

No problem.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/11447049
> 
> 
> I'm not saying to make your room totally dead. But there's a good amount of leeway with this, and generally more absorption leads to cleaner sound that is _more_ realistic and lifelike.
> 
> 
> --Ethan



Ethan:


You have stated that you use 38 traps in your living room. How big is each trap? Does a trap that goes from floor to ceiling in a corner count as a single trap or a combination of several?


For 1st reflection absorption in a home theater, you seem to recommend 2" rigid fiberglass. Dennis Erskine seems to recommend 1" on the grounds that 2" may be too deadening. Have I understood your position accurately? What is appropriate thickness for side reflection? This is where the art takes over from the science

perhaps. Or perhaps, your personal preference for a music listening room vice Dennis' for home theaters dictate different treatments? For example, you are no fan of dipole surrounds, but I am sure that Dennis would not want a good home theater without them.


My planned theater is rectangular (28' deep, 18' wide at screen, 16' wide at rear row, and 8.5' high ceilings) with a carpet floor. I will follow your advice on traps and 1st reflection treatment. Should I consider ceiling reflection absorption as well if my floor will be carpeted? (For what it is worth, I plan to use Atlantic Technology speakers and the manufacturer tells me that their 8200 THX model is designed to not have much significant vertical dispersion (ie. towards the ceiling))


Also, given my 28' long room, I am planning on putting a sub towards the rear vice front to put it closer to the listening position for greater effect. (I'll bass trap all corners). Is rear positioning OK or is the front preferred? Putting it in the front would mean requiring more power to drive it I think. Closer to seating would require less. Edit: I came across this article: http://www.realtraps.com/art_sub-placement.htm Will read it in full


Thanks


----------



## DIYHomeTheater

Quote:

Originally Posted by *Ethan Winer* 
Most rooms have 12 corners!










--Ethan
Ethan:


Do you mean 12 'edges'? I consider a corner to be where the walls/ceiling or walls/floor meet. So, 12 edges and 8 corners. Correct?


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14595605
> 
> 
> FSK is good for corner bass traps, but not for absorbers at reflection points. More here:
> 
> Density Report
> 
> 
> --Ethan



Very useful. How and why does FRK affect absorption? It is such a thin layer that I thought it would have no effect! But, it does.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/14996928
> 
> 
> However, you could apply a new facing to what is now the front surface of the entire trap, which is really all those 2-inch edges. That not only reduces absorption at higher frequencies, but increases bass absorption too.
> 
> 
> --Ethan



Why does adding facing INCREASE bass absorption?


----------



## nathan_h




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/0
> 
> 
> 
> Ethan:
> 
> 
> You have stated that you use 38 traps in your living room. How big is each trap? Does a trap that goes from floor to ceiling in a corner count as a single trap or a combination of several?



Check out the photos and videos of his room on his site. Each trap is 2' X 4' except some at corners that are 2'x2' iirc.



> Quote:
> For 1st reflection absorption in a home theater, you seem to recommend 2" rigid fiberglass. Dennis Erskine seems to recommend 1" on the grounds that 2" may be too deadening. Have I understood your position accurately? What is appropriate thickness for side reflection? This is where the art takes over from the science
> 
> perhaps. Or perhaps, your personal preference for a music listening room vice Dennis' for home theaters dictate different treatments? For example, you are no fan of dipole surrounds, but I am sure that Dennis would not want a good home theater without them.



I would be very surprised if Dennis at any time said 2'' is less good than 1'' for side panel thickness. That would contradict every measurement I have seen.


One might reasonably argue that sometimes diffusion is better than absorption but essentially never that one wants thinner absorption.



> Quote:
> My planned theater is rectangular (28' deep, 18' wide at screen, 16' wide at rear row, and 8.5' high ceilings) with a carpet floor. I will follow your advice on traps and 1st reflection treatment. Should I consider ceiling reflection absorption as well if my floor will be carpeted? (For what it is worth, I plan to use Atlantic Technology speakers and the manufacturer tells me that their 8200 THX model is designed to not have much significant vertical dispersion (ie. towards the ceiling))
> 
> 
> Also, given my 28' long room, I am planning on putting a sub towards the rear vice front to put it closer to the listening position for greater effect. (I'll bass trap all corners). Is rear positioning OK or is the front preferred? Putting it in the front would mean requiring more power to drive it I think. Closer to seating would require less. Edit: I came across this article: http://www.realtraps.com/art_sub-placement.htm Will read it in full
> 
> 
> Thanks



That's gonna be a nice space! You should consider starting a dedicated build thread with photos and details of the plan and progress. You'll get lots of good encouragement and maybe some good advice










about sub placement: Unless you are sitting next to a sub for tactile reasons, placement close or far is not the key. The key is how the sub interacts with the room modes. It is going to have to "fill" the room ("pressurize" it). Placement should be determined by where it sounds best when doing that. A quick search on the "crawling" method for sub placement will show you what I am talking about.


----------



## nathan_h




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/0
> 
> 
> 
> Ethan:
> 
> 
> Do you mean 12 'edges'? I consider a corner to be where the walls/ceiling or walls/floor meet. So, 12 edges and 8 corners. Correct?



Yep.


----------



## Brad Horstkotte

FRK = Foil Reinforced Kraft paper (a.k.a. FSK = Foil Scrim Kraft paper, a.k.a. Scrim) - it has a thin layer of metallic foil (thin but not very porous).


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *nathan_h* /forum/post/20070462
> 
> 
> I would be very surprised if Dennis at any time said 2'' is less good than 1'' for side panel thickness. That would contradict every measurement I have seen.
> 
> 
> One might reasonably argue that sometimes diffusion is better than absorption but essentially never that one wants thinner absorption.
> 
> 
> That's gonna be a nice space! You should consider starting a dedicated build thread with photos and details of the plan and progress. You'll get lots of good encouragement and maybe some good advice



Nathan:


Thanks. I recall reading that suggestion from Dennis Erskine on this thread. Check this post from him 

It is post #6 on this thread.


My build thread is on my signature below. If you look at the voting button that I have established, the naysayers and cheering squad are about evenly split


----------



## nathan_h




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20070871
> 
> 
> Nathan:
> 
> 
> Thanks. I recall reading that suggestion from Dennis Erskine on this thread. Check this post from him
> 
> It is post #6 on this thread.
> 
> 
> My build thread is on my signature below. If you look at the voting button that I have established, the naysayers and cheering squad are about evenly split



I'm gonna say, in context, Dennis was talking about very large areas (full front wall and side wall all around up to ear level) being problematic (=leaving one open to absorbing too much). Stick with less coverage (eg, first reflection points) and thick panels at those points, for more reliable results.


Nice build thread! That's gonna be a great space.


The thread poll is pretty general, so it's not clear what the pro and con votes indicate....


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20069083
> 
> 
> You have stated that you use 38 traps in your living room. How big is each trap? Does a trap that goes from floor to ceiling in a corner count as a single trap or a combination of several?



Actually, I have 55 panels now.










The photos below are fairly recent, and Yes, I think I'm done!



> Quote:
> For 1st reflection absorption in a home theater, you seem to recommend 2" rigid fiberglass.



The thicker the better, always. First reflections are mainly a mid/high frequency issue, but more bass trapping from using even thicker panels is always welcome. A panel thicker doesn't absorb more per se. Rather, it extends the same absorption to lower frequencies. So while even one inch thick is adequate, thicker is only better. And Yes, absorbing ceiling reflections is important too for most speaker types.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20070128
> 
> 
> Do you mean 12 'edges'? I consider a corner to be where the walls/ceiling or walls/floor meet. So, 12 edges and 8 corners. Correct?



There are four corners where each wall meets another wall, four more where each wall meets the ceiling, and four more where each wall meets the floor. I'm talking about "normal" corners, not tri-corners where three boundaries meet. There are eight of those in a rectangle room.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20070461
> 
> 
> Why does adding facing INCREASE bass absorption?



The membrane vibrates when sound waves strike it, and the fiberglass the membrane is bonded to damps that vibration.


--Ethan


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20071055
> 
> 
> The membrane vibrates when sound waves strike it, and the fiberglass the membrane is bonded to damps that vibration.
> 
> 
> --Ethan



Thanks for your answers. Should the membrane be facing into the room or away from it? I would think the latter, right?


----------



## nathan_h

Into the room.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/17447263
> 
> 
> 
> * Diffusion can be used on the front wall behind dipole speakers if the listener prefers more ambience, but wants to avoid the small-room boxy sound often caused by leaving those early reflections untreated.
> 
> 
> --Ethan



I am confused. Dipoles are used as side and rear surrounds on the side and rear walls, respectively. Where is the 'front wall behind dipole speakers'?


----------



## vinyl




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20071541
> 
> 
> I am confused. Dipoles are used as side and rear surrounds on the side and rear walls, respectively. Where is the 'front wall behind dipole speakers'?











*Dipole speakers with mostly diffused front wall.*


----------



## nathan_h

That's a sexy picture. What brand/model are those diffusers?


----------



## vinyl




> Quote:
> Originally Posted by *nathan_h* /forum/post/20071964
> 
> 
> What brand/model are those diffusers?



Auralex Acoustics: T’Fusors / Q’Fusors


----------



## DIYHomeTheater

Ethan:


How does one fashion a theater seat riser into a bass trap? Is it effective? Thanks for all the education that your website provides.


How would you modify your recommendations here for placing the LCR behind an acoustically transparent screen? Would you still toe-in the speakers?


----------



## mtbdudex

Quote:

Originally Posted by *DIYHomeTheater* 
Ethan:


How does one fashion a theater seat riser into a bass trap? Is it effective?
Ethan W gave me advice on that for my riser, read here:
riser: Broadband bass trap 

(Based upon Dennis E work/articles also.)


Is it effective? Yes - every bass trap helps.


----------



## DIYHomeTheater

Ethan:

Is an air gap recommended for the absorbers at the 1st reflection points, or can the absorber be mounted right against the wall? Thanks


Mtbdudex, Vinyl: Thanks for your responses.


Mtbdudex: What is the theory behind the design of risers as absorbers?


I found this article on risers as bass traps: http://www.audioholics.com/tweaks/do...ter-seat-riser . Elsewhere I found a critique of this design that essentially said that front facing holes are not quite as effective as 1/4" x 48" slits on the top of the decking.


----------



## nathan_h

Air gaps help increase the range of frequencies that are impacted by a trap -- typically a good thing when that means more bass is trapped -- hence the emphasis on "broad band" treatments...


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *nathan_h* /forum/post/20073633
> 
> 
> Air gaps help increase the range of frequencies that are impacted by a trap -- typically a good thing when that means more bass is trapped -- hence the emphasis on "broad band" treatments...



Nathan:

So, you would recommend a gap for the 1st reflection points as well? If so, how much? What is the point of diminishing returns from a gap (if any)? Thanks


----------



## mtbdudex




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20073252
> 
> 
> Mtbdudex: What is the theory behind the design of risers as absorbers?
> 
> 
> I found this article on risers as bass traps: http://www.audioholics.com/tweaks/do...ter-seat-riser . Elsewhere I found a critique of this design that essentially said that front facing holes are not quite as effective as 1/4" x 48" slits on the top of the decking.


 http://www.avsforum.com/avs-vb/showt...9#post20007129 


> Quote:
> 
> 
> 
> Quote:
> Originally Posted by *pgodden* /forum/post/20005997
> 
> 
> Yes I read your link, (Good Read Actually) I didnt catch on though about you doing it wrong initially, now I get it. Are the vents on the top absolutely required then? I would assume they are. I am now thinking 2 x 10 around the edges and 2 x 6 in the middle.
> 
> 
> 
> 
> As Ethan W taught me, yes, for an effective broadband bass trap you need all those, as much as possible.
> 
> At first, I cut just a few 4" x 14", then more, and finally all along the perimeter.
> 
> 
> There are some more advanced analysis that people have done where they know (via analysis and/or room measurement confirmation) a room mode will be an issue, and have turned the riser into a Helmholtz absorber via cutting specific width/length slit(s) in the riser....
> 
> I've read about that and visited a persons who's HT had that done for him.
> *However, for laypeople like us going the safe route with a broadband bass trap is the easiest and surest method.*
Click to expand...


----------



## DIYHomeTheater




Ethan Winer said:


> Actually, I have 55 panels now.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The photos below are fairly recent, and Yes, I think I'm done!
> 
> 
> 
> 
> The thicker the better, always. First reflections are mainly a mid/high frequency issue, but more bass trapping from using even thicker panels is always welcome. A panel thicker doesn't absorb more per se. Rather, it extends the same absorption to lower frequencies. So while even one inch thick is adequate, thicker is only better. And Yes, absorbing ceiling reflections is important too for most speaker types.
> 
> 
> --Ethan
> 
> 
> Ethan:
> 
> With all this treatment what does the frequency response at your listening position look like?


----------



## nathan_h




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/0
> 
> 
> Nathan:
> 
> So, you would recommend a gap for the 1st reflection points as well? If so, how much? What is the point of diminishing returns from a gap (if any)? Thanks



Rule of thumb rather than science I can cite is the gap should not be thicker than the panel itself, and in practice is often 1 or 2 inches for a 2 to 4 inch thick panel.


That said, in ceiling installations people often leave an even bigger gap, and in corner straddling installations of course the gap is bigger, so there is no reason to shy away from using the space if you have it.


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20074485
> 
> 
> With all this treatment what does the frequency response at your listening position look like?



Given how terrible the LF response and ringing are in most rooms, I think mine is very good. This is an older plot, from before I added the last round of traps:


----------



## Tireman1

Ethan,


Have the 705 foil out in some areas. Would a light dusting of flat spray paint cause any problems? The reflection shows through the GOM 701 at some angles.


Thanks,


----------



## pepar




> Quote:
> Originally Posted by *Tireman1* /forum/post/20076256
> 
> 
> Ethan,
> 
> 
> Have the 705 foil out in some areas. Would a light dusting of flat spray paint cause any problems? The reflection shows through the GOM 701 at some angles.
> 
> 
> Thanks,



I'd be concerned that the "dust" would come off and become airborne. I'm pretty sure that it will not adhere. And the foil will definitely flex.


Something to ponder.










Jeff


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20075489
> 
> 
> Given how terrible the LF response and ringing are in most rooms, I think mine is very good. This is an older plot, from before I added the last round of traps:



Ethan:

That looks great! Thx


----------



## DIYHomeTheater

Ethan

What are your thoughts on using risers as additional bass traps?

Thanks


----------



## mtbdudex




> Quote:
> Originally Posted by *Tireman1* /forum/post/20076256
> 
> 
> Ethan,
> 
> 
> Have the 705 foil out in some areas. Would a light dusting of flat spray paint cause any problems? The reflection shows through the GOM 701 at some angles.
> 
> 
> Thanks,



Can you cover the foil with something else you might have on hand, like kraft paper?

That's what I did on my bass traps


----------



## myfipie




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20077657
> 
> 
> Can you cover the foil with something else you might have on hand, like kraft paper?
> 
> That's what I did on my bass traps



Oh yes craft paper will work just fine. Another thing you can use is something like 80# card stock (the paper used for most business cards).


Glenn


----------



## dunkman23

will having acoustic panels just in the rear wall of my HT help my sound?


----------



## Jay5298

Well, I finally finished my bass traps. I don't have any measuring equipment so I can't show you how they have helped on a graph. To my "naked" ear they seem to have helped even out the bass around the room and things seem a little tighter. I watched "The Town" last night and the deep bass scenes sounded great. I think my next project will be to add some panels on the side walls. Probably 2" thick and maybe only two at the most on each side. I don't have a very good camera, so the pictures are sort of dim.


----------



## NicksHitachi




> Quote:
> Originally Posted by *Jay5298* /forum/post/0
> 
> 
> Well, I finally finished my bass traps. I don't have any measuring equipment so I can't show you how they have helped on a graph. To my "naked" ear they seem to have helped even out the bass around the room and things seem a little tighter. I watched "The Town" last night and the deep bass scenes sounded great. I think my next project will be to add some panels on the side walls. Probably 2" thick and maybe only two at the most on each side. I don't have a very good camera, so the pictures are sort of dim.



What are the dimensions of your room?


----------



## nathan_h




> Quote:
> Originally Posted by *dunkman23* /forum/post/0
> 
> 
> will having acoustic panels just in the rear wall of my HT help my sound?



Yes. Obviously, a few more in key spots would also help more, but if that's all you can do, it is worth it, sure.


----------



## nathan_h




> Quote:
> Originally Posted by *Jay5298* /forum/post/0
> 
> 
> Well, I finally finished my bass traps. I don't have any measuring equipment so I can't show you how they have helped on a graph. To my "naked" ear they seem to have helped even out the bass around the room and things seem a little tighter. I watched "The Town" last night and the deep bass scenes sounded great. I think my next project will be to add some panels on the side walls. Probably 2" thick and maybe only two at the most on each side. I don't have a very good camera, so the pictures are sort of dim.



Looks sharp. Glad to hear it sounds good. I think you will like having a couple of side wall absorbers.


----------



## mtbdudex




> Quote:
> Originally Posted by *Jay5298* /forum/post/20080457
> 
> 
> Well, I finally finished my bass traps.



Looks good Jay!


----------



## Ethan Winer




> Quote:
> Originally Posted by *Tireman1* /forum/post/20076256
> 
> 
> Have the 705 foil out in some areas. Would a light dusting of flat spray paint cause any problems?



Other than Jeff's concern, which I've never seen happen, thin paint is fine. Of course, be sure the shiny foil is perfectly clean and dry before you paint it.


--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20077649
> 
> 
> What are your thoughts on using risers as additional bass traps?



I've never done that so I have no strong opinion. I'm not sure that a riser is the best place for a bass trap, though more bass trapping can only help. I can tell you for sure that the more conventional trap locations are very important.


--Ethan


----------



## pepar

DIYHomeTheater, I can tell you that my riser was built to allow the future installation of a bass transducer .. 2x12 frame w/2x10 "joists" .. but it was not necessary. It has a fortuitous sympathetic springy "whomp" at about 25Hz. I'm sure that means it is absorbing at and around that frequency, but I wouldn't know how to place any values on it.


Jeff


----------



## Jay5298




> Quote:
> Originally Posted by *Tireman1* /forum/post/20076256
> 
> 
> Ethan,
> 
> 
> Have the 705 foil out in some areas. Would a light dusting of flat spray paint cause any problems? The reflection shows through the GOM 701 at some angles.
> 
> 
> Thanks,



It may be too late, but I removed the foil and then flipped it so the plain side was up and re-attached it with spray adhesive.


----------



## Jay5298




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/20080543
> 
> 
> What are the dimensions of your room?



The worst dimensions possible, 8ft ceiling(actually 7ft,10in.) 16 1/2 ft wide, 24 ft deep. I was stuck with the low ceiling so when I plugged in the numbers with the recommended ratios I didn't like the dimensions it gave me. I built the room based on the screen size I wanted, and the number of seats. I wanted to be able to just walk into the room with a 3 foot isle on each side. Not only for ease of moving around but so the side seats wouldn't be too close to the surround speakers. I also didn't want to sit too close to the screen. If I did some measurements it probably wouldn't look good but it sounds pretty good to me.


----------



## dunkman23




> Quote:
> Originally Posted by *nathan_h* /forum/post/20080655
> 
> 
> Yes. Obviously, a few more in key spots would also help more, but if that's all you can do, it is worth it, sure.



i was looking to make 24x 48 sized ones. But im debating if i should do 2 or 4 inch ones.. what would u recommend


----------



## pauleyc

So I have a non-HT acoustics question, so slightly off topic. A few years ago we built a home on a piece of lakefront property we had, and at the time we wanted all hardwood in the main living space. The main space is a causal family room, dinning and kitchen combination. The issue is that the room is very LIVE. I would guess the room is 25 x 30 and as you can see it's pretty much hard surface after hard surface. It so bad that it's difficult to listen to the tv and nearly impossible if others are having conversations elsewhere in the room. I'm looking for ideas on how to tame the room a little. We originally didn't want curtains because we didn't want to take away from the views however I'm beginning to think heavy drapes, even if they are never closed. Also, the back wall that you can't see (on the left) is a fairly large flat surface. I was thinking a few 2x48x2" panels along that wall. There aren't a lot of other big wall spaces. Any thoughts or suggestions? See pic.


----------



## Brad Horstkotte

A large area rug would help, but of course would cover up some of the hardwood.


----------



## Dennis Erskine

How much you will to spend to fix this?


----------



## DIYHomeTheater

Quote:

Originally Posted by *pauleyc* 
So I have a non-HT acoustics question, so slightly off topic. A few years ago we built a home on a piece of lakefront property we had, and at the time we wanted all hardwood in the main living space. The main space is a causal family room, dinning and kitchen combination. The issue is that the room is very LIVE. I would guess the room is 25 x 30 and as you can see it's pretty much hard surface after hard surface. It so bad that it's difficult to listen to the tv and nearly impossible if others are having conversations elsewhere in the room. I'm looking for ideas on how to tame the room a little. We originally didn't want curtains because we didn't want to take away from the views however I'm beginning to think heavy drapes, even if they are never closed. Also, the back wall that you can't see (on the left) is a fairly large flat surface. I was thinking a few 2x48x2" panels along that wall. There aren't a lot of other big wall spaces. Any thoughts or suggestions? See pic.
Pauleyc:


Do yourself a favor. Perform an advanced search on this thread singling out posts by Ethan Winer. Read them. He provides some very consistent, basic and fundamental advice. If you build the absorbers yourself, you should be able achieve good results at minimal cost.


Even better, read his artciles on Ethanwiner.com or realtraps.com


----------



## yacht422

will 1/8" wood work as well(or better) than kraft paper when 'facing' super chunks?


----------



## pauleyc

Quote:

Originally Posted by *Brad Horstkotte* 
A large area rug would help, but of course would cover up some of the hardwood.
There is a rug around the seating area, but I think thinker carpet might help. Its a rather low nap carpet.

Quote:

Originally Posted by *Dennis Erskine* 
How much you will to spend to fix this?
I would like to spend $500-$2000 depending on the level of expected return. In other words, I would like to spend a little and get a lot *smile*

Quote:

Originally Posted by *DIYHomeTheater* 
Pauleyc:


Do yourself a favor. Perform an advanced search on this thread singling out posts by Ethan Winer. Read them. He provides some very consistent, basic and fundamental advice. If you build the absorbers yourself, you should be able achieve good results at minimal cost.


Even better, read his artciles on Ethanwiner.com or realtraps.com
I have read a lot of Ethan's site as well as watched his youtube videos .. but I'm far from knowledgeable on the subject. I'm actually building four DIY corner traps for my HT. My issue is that I'm not trying to make this a HT. I just want to tame the slap echo and was looking for any "low hanging fruit" techniques that I can do easily. This property is also a rental in the summer, so hanging panels everywhere isn't an option.


----------



## pepar

Quote:

Originally Posted by *pauleyc* 
There is a rug around the seating area, but I think thinker carpet might help. Its a rather low nap carpet.
Look at the thickest spongy PADDING you can find for under it. Low nap .. high nap .. probably wouldn't make much difference.


----------



## pepar

Quote:

Originally Posted by *pauleyc* 
I have read a lot of Ethan's site as well as watched his youtube videos .. but I'm far from knowledgeable on the subject. I'm actually building four DIY corner traps for my HT. My issue is that I'm not trying to make this a HT. I just want to tame the slap echo and was looking for any "low hanging fruit" techniques that I can do easily. This property is also a rental in the summer, so hanging panels everywhere isn't an option.
Then you are probably limited to standing partitions that you can take with you. There really isn't much alternative if you want to reduce the slap echo and don't want to hang panels.


----------



## Brad Horstkotte

Wall hung tapestries would be another option to cover some of the parallel hard surfaces.


----------



## abl1207




> Quote:
> Originally Posted by *Jay5298* /forum/post/0
> 
> 
> Well, I finally finished my bass traps. I don't have any measuring equipment so I can't show you how they have helped on a graph. To my "naked" ear they seem to have helped even out the bass around the room and things seem a little tighter. I watched "The Town" last night and the deep bass scenes sounded great. I think my next project will be to add some panels on the side walls. Probably 2" thick and maybe only two at the most on each side. I don't have a very good camera, so the pictures are sort of dim.



Looks like a great theater. I am looking a building my own. I liked the look of your theater seats. Who is the manufacturer and what model. Were you happy with the place you bought from.


----------



## zyad

Great thread everyone... a ton of info, but it can get a little too technical for us noobs.

I'm looking for simple advice for a simple small theatre room I'm starting in my basement.

I already have acoustic paneling, and just trying to figure out the ideal (and most attractive way) to clad the walls and still get good performance. I do however have some physical limitations.


Some stats:

- Room is 12' wide x 15' long. Ceiling height is only 7'-6"

- Sectional sofa (I do not like theatre chairs) will be right against the rear wall.

- System will be 7.1, screen will be 10' diagonal.

- Floor will be carpet. Ceiling drywall.


Here are my limitations:

- Sitting location will be right against rear wall due to smal size of room.

- Front wall will have custom cabinetry around and below the screen. I need this for function and I like the look. Therefore, acoustic paneling at the screen wall is not an option.


Looking around this thread and other online references, am I right in deducing that:

- Best paneling option would be for me to clad the side walls halfway up (i.e. to ear level)?


My questions:

- Since I can't clad the screen front wall: Should I be cladding the rear wall (right behind the sofa) all the way up to the ceiling?

- What speaker height is ideal? If at ear level, I kind of wanted to hide them behind the acoustic paneling (and cut out the foam at those spots to allow the sound through. My speakers are not in-wall, they're bookshelfs but will be placed inside recessed "boxes" within the wall partitions.

- Should I point all speakers to the centre seat area?

- Is the middle of the front wall the best place for the sub?


I would have liked to fully clad all the walls of the room (except the front one with the cabinetry), but from what's I'm reading, that sounds like a foolish decision because it would make the room too "dead" acoustically without enough sound refelction??!?!? Is this true?


----------



## nathan_h




> Quote:
> Originally Posted by *dunkman23* /forum/post/0
> 
> 
> 
> i was looking to make 24x 48 sized ones. But im debating if i should do 2 or 4 inch ones.. what would u recommend



4 inch thick is better.


----------



## nathan_h




> Quote:
> Originally Posted by *yacht422* /forum/post/0
> 
> 
> will 1/8" wood work as well(or better) than kraft paper when 'facing' super chunks?



You want something that will flex more/permit more bass energy through, which is why paper or foil or fabric are the popular choices.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/9839792
> 
> 
> I agree with much of that, but with a few caveats:
> 
> 
> Once all of the early reflection points are treated with absorption (or possibly diffusion), other sources of ambience are not particularly damaging. But in the case of dipole speakers, reflections off the front wall are early too. The main problem is not Haas as far as I'm concerned - rather, it's the horribly skewed frequency response from all those separate comb filtering sources.
> 
> 
> --Ethan



Ethan:


I assume that you referring to use of dipole LCRs primarily above. Would front treatment be needed if one is using dipole surrounds? What is your opinion on dipole surrounds? I understand that it is a THX requirement for home theater surrounds. I know that you are not wildly enthusiastic about dipoles - does this extend to surrounds as well in a *dedicated home theater* vice living room?


Thanks


----------



## nezff

Im looking to do some treatments to my room, just to mainly cut down on the echo. The room is rather large at 30x15. Any advice would be greatly appreciated. My room is in my signature.


thanks in advance


----------



## SierraMikeBravo

^^^^


Wow! Deja vu! I think I just did a layout for a room that was just like yours except for the paint color.


----------



## zyad




> Quote:
> Originally Posted by *zyad* /forum/post/20088707
> 
> 
> Great thread everyone... a ton of info, but it can get a little too technical for us noobs.
> 
> I'm looking for simple advice for a simple small theatre room I'm starting in my basement.
> 
> I already have acoustic paneling, and just trying to figure out the ideal (and most attractive way) to clad the walls and still get good performance. I do however have some physical limitations.
> 
> 
> Some stats:
> 
> - Room is 12' wide x 15' long. Ceiling height is only 7'-6"
> 
> - Sectional sofa (I do not like theatre chairs) will be right against the rear wall.
> 
> - System will be 7.1, screen will be 10' diagonal.
> 
> - Floor will be carpet. Ceiling drywall.
> 
> 
> Here are my limitations:
> 
> - Sitting location will be right against rear wall due to smal size of room.
> 
> - Front wall will have custom cabinetry around and below the screen. I need this for function and I like the look. Therefore, acoustic paneling at the screen wall is not an option.
> 
> 
> Looking around this thread and other online references, am I right in deducing that:
> 
> - Best paneling option would be for me to clad the side walls halfway up (i.e. to ear level)?
> 
> 
> My questions:
> 
> - Since I can't clad the screen front wall: Should I be cladding the rear wall (right behind the sofa) all the way up to the ceiling?
> 
> - What speaker height is ideal? If at ear level, I kind of wanted to hide them behind the acoustic paneling (and cut out the foam at those spots to allow the sound through. My speakers are not in-wall, they're bookshelfs but will be placed inside recessed "boxes" within the wall partitions.
> 
> - Should I point all speakers to the centre seat area?
> 
> - Is the middle of the front wall the best place for the sub?
> 
> 
> I would have liked to fully clad all the walls of the room (except the front one with the cabinetry), but from what's I'm reading, that sounds like a foolish decision because it would make the room too "dead" acoustically without enough sound refelction??!?!? Is this true?



Bump...


Any help would be greatly appreciated guys. I'm doing this work in the next couple of weeks and I need to plan ahead.

Thanks.


----------



## nezff




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20095728
> 
> 
> ^^^^
> 
> 
> Wow! Deja vu! I think I just did a layout for a room that was just like yours except for the paint color.



really! well any advice you can throw at me, Im all ears


----------



## nathan_h




> Quote:
> Originally Posted by *zyad* /forum/post/20095768
> 
> 
> Bump...
> 
> 
> Any help would be greatly appreciated guys. I'm doing this work in the next couple of weeks and I need to plan ahead.
> 
> Thanks.



I'm going to recommend you focus on putting panels at the first reflection points on the side walls, and at head level on the rear wall. Do a search for the mirror method and you'll be placing them all in the right locations.


Don't clad the walls en masse.


You should also consider bass traps. Ethan's "realtraps" web site has excellent information about where to locate those.


----------



## nathan_h




> Quote:
> Originally Posted by *nezff* /forum/post/20095691
> 
> 
> Im looking to do some treatments to my room, just to mainly cut down on the echo. The room is rather large at 30x15. Any advice would be greatly appreciated. My room is in my signature.
> 
> 
> thanks in advance



Deja vu but here's a good starting point:


Focus on putting panels at the first reflection points on the side walls. The rear wall looks a little full for panels. Do a search for the mirror method and you'll be placing them all in the right locations, even with your slanted walls.


Don't clad the walls en masse.


You should also consider bass traps. Ethan's "realtraps" web site has excellent information about where to locate those. They will help a lot.


----------



## nezff




> Quote:
> Originally Posted by *nathan_h* /forum/post/20096021
> 
> 
> Deja vu but here's a good starting point:
> 
> 
> Focus on putting panels at the first reflection points on the side walls. The rear wall looks a little full for panels. Do a search for the mirror method and you'll be placing them all in the right locations, even with your slanted walls.
> 
> 
> Don't clad the walls en masse.
> 
> 
> You should also consider bass traps. Ethan's "realtraps" web site has excellent information about where to locate those. They will help a lot.



I dont have alot of funds to just go all out, so the panels will probably be my first thing to do. I though about spacing them out on the angled wall and low walls to keep the room looking good.


----------



## zyad




> Quote:
> Originally Posted by *nathan_h* /forum/post/20096007
> 
> 
> I'm going to recommend you focus on putting panels at the first reflection points on the side walls, and at head level on the rear wall. Do a search for the mirror method and you'll be placing them all in the right locations.
> 
> 
> Don't clad the walls en masse.
> 
> 
> You should also consider bass traps. Ethan's "realtraps" web site has excellent information about where to locate those.



Thanks for the advice.

So are you saying that, if I have the surrounds at about 4' height, it isn't recommended the wrap the perimeter in acoustic panelling (up to say 3')?


----------



## Jay5298




> Quote:
> Originally Posted by *abl1207* /forum/post/20088454
> 
> 
> Looks like a great theater. I am looking a building my own. I liked the look of your theater seats. Who is the manufacturer and what model. Were you happy with the place you bought from.



Thanks. They are Berkline 13175(Tangiers) I got them from www.theaterseatstore.com/ . I like them because they have a tall back, I'm 6'3" so they fit me well. I also like that they are only 10ft wide for 4 chairs, yet they still have a 25" width for the seat. I was able to put 2 rows of 4 and I have 3 ft on each side for my isle. The only drawback to them is the small cupholders. The diameter is pretty small, but a can of beer fits perfectly







They have powerbuys on this site from time to time, so you can probably get them at a good price. I was able to get a great deal because they have a warehouse near my house so I didn't have to pay shipping.


----------



## nezff

I got my Berkline Tangiers at Stargate Cinema, for a killer deal. Check there first.


----------



## mtbdudex




> Quote:
> Originally Posted by *Jay5298* /forum/post/20096919
> 
> 
> Thanks. They are Berkline 13175(Tangiers) I got them from www.theaterseatstore.com/ . I like them because they have a tall back, I'm 6'3" so they fit me well. I also like that they are only 10ft wide for 4 chairs, yet they still have a 25" width for the seat. I was able to put 2 rows of 4 and I have 3 ft on each side for my isle. The only drawback to them is the small cupholders. The diameter is pretty small, but a can of beer fits perfectly
> 
> 
> 
> 
> 
> 
> 
> They have powerbuys on this site from time to time, so you can probably get them at a good price. I was able to get a great deal because they have a warehouse near my house so I didn't have to pay shipping.





> Quote:
> Originally Posted by *nezff* /forum/post/20096941
> 
> 
> I got my Berkline Tangiers at Stargate Cinema, for a killer deal. Check there first.



Not to stray to off topic of "acoustics", but don't forget the AVS store and dealing with Roman, there are great deals here as well.
http://shop.avscience.com/Berkline-Seating_c_37.html , I just ordered my (4) Berkline 12006 power recliners in curve layout "lOVOOVOl" for my 1st row from him, getting them next week.


----------



## Jay5298

"They have powerbuys on this site from time to time, so you can probably get them at a good price."


What I said.


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20092365
> 
> 
> I assume that you referring to use of dipole LCRs primarily above. Would front treatment be needed if one is using dipole surrounds? What is your opinion on dipole surrounds? I understand that it is a THX requirement for home theater surrounds. I know that you are not wildly enthusiastic about dipoles - does this extend to surrounds as well in a *dedicated home theater* vice living room?



I'm not a fan of dipole speakers, but I've heard some that sound fine. I wouldn't buy them for many reasons, including cost versus performance plus the fact that all those back waves need to be dealt with. I'm not aware of any "requirement" for dipoles. Where exactly did you read that? Actually, never mind, it doesn't matter.










--Ethan


----------



## Ethan Winer




> Quote:
> Originally Posted by *nezff* /forum/post/20095691
> 
> 
> Im looking to do some treatments to my room, just to mainly cut down on the echo. The room is rather large at 30x15. Any advice would be greatly appreciated. My room is in my signature.



All of the usual advice applies: Bass traps in as many corners as possible, plus mid/high frequency absorbers at the side-wall and ceiling reflection points. If you have the budget, diffusors along the rear wall (in front of the doors) add a nice sense of spaciousness. More here:

Acoustic Basics 


--Ethan


----------



## DIYHomeTheater

Quote:

Originally Posted by *Ethan Winer*
I'm not a fan of dipole speakers, but I've heard some that sound fine. I wouldn't buy them for many reasons, including cost versus performance plus the fact that all those back waves need to be dealt with. I'm not aware of any "requirement" for dipoles. Where exactly did you read that? Actually, never mind, it doesn't matter.










--Ethan
Don't dipole surounds offer an immersive experience on surrounds that bipoles can't match?


----------



## Brad Horstkotte

Quote:

Originally Posted by *DIYHomeTheater* 
Don't dipole surounds offer an immersive experience on surrounds that nipples can't match?
Best iPhone auto-correction ever! Sig worthy!


----------



## erkq

Quote:

Originally Posted by *DIYHomeTheater* 
Don't dipole surounds offer an immersive experience on surrounds that nipples can't match?
If you want your listening environment to add muddy phase aberrations that the recording engineers never intended, then by all means use di-poles. Some people like that. I prefer to let the recording engineers immerse me as they want.


----------



## btinindy




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/0
> 
> 
> 
> Best iPhone auto-correction ever! Sig worthy!



Those must be some really good dipoles.


----------



## pepar




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20098762
> 
> 
> Don't dipole surounds offer an immersive experience on surrounds that bipoles can't match?



Wasn't the context dipole LCR?


----------



## Ethan Winer




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20098762
> 
> 
> Don't dipole surounds offer an immersive experience on surrounds that bipoles can't match?



I can't imagine why. When movie soundtracks are mixed, all required ambience is added in the proportion the mix engineers deem appropriate.


--Ethan


----------



## pepar

For surround channels, T Holman hit upon dipoles to simulate the surround _arrays_ used in commercial cinemas. They are to more faithfully reproduce the artist's intent than a single monopole would do in the small space of a home theater.


----------



## nathan_h

Dipole surrounds were really important in the early home cinema days when surround mixes had mono surround channels and/or were the movie theater mixes. The fudging around that dipoles introduced indeed created an envelopement that helped obfuscate the negatives of the technology and process at the time (early 1990s).


These days, surround mixes have separate discrete (dare I say "stereo") channels, are often mixed and/or equalized for the home video release, and sound most like what the mixer heard when reproduced using direct radiating speakers in a well set up room.


I've only been on and seen photos of the layout of a handful of mixing stages, but they all use direct radiating speakers for the surround channels.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar* /forum/post/20102181
> 
> 
> For surround channels, T Holman hit upon dipoles to simulate the surround _arrays_ used in commercial cinemas. They are to more faithfully reproduce the artist's intent than a single monopole would do in the small space of a home theater.



That really depends on knowing what the 'artist' intended.


I see the use of dipoles or bipoles as part of the early evolution of surround sound because they avoided the direct radiation of the surround channels to the listener and created a diffuse sound field. These days, and particularly with discrete multichannel music (as well as cinema), I much prefer the specificity of monopoles.


----------



## pepar





> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/20102437
> 
> 
> That really depends on knowing what the 'artist' intended.
> 
> 
> I see the use of dipoles or bipoles as part of the early evolution of surround sound because they avoided the direct radiation of the surround channels to the listener and created a diffuse sound field. These days, and particularly with discrete multichannel music (as well as cinema), I much prefer the specificity of monopoles.



I have recently tried the Tripole mode for my surrounds and think it made a huge improvement .. a nice balance. Plus the surrounds are aimed so that the direct radiated component goes "over the head" of the near seat and gives the surround channel more presence at the _far_ seat.


However, for all of the in-the-band SACD/DVD-A content I have, I manually swap monopoles at 125 degrees identical to LCR and swap in the corresponding Audyssey Pro file as well.


I've tried the monopoles for movies and concerts and the tripoles for SACD/DVD-A, but they just don't cross over, so I work around.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *pepar* /forum/post/20099487
> 
> 
> Wasn't the context dipole LCR?



That's what I thought, too - that LCRs should not be dipole. I realize now that Ethan is averse to dipoles for surrounds as well. The THX specification is dipole for surrounds for home cinema.


----------



## Dennis Erskine

Theatrical mixes (movies) are done on the presumption the side surround channels will consist of an array of multiple monopolar speakers. Directivity and "pin pointing" side surround effects cannot be achieved in this type of environment. The dipole design best preserves this array effect when a single left or right side surround is utilized.


When multiple rows of seats are utilized in a residential setting, the multiple monopole side surrounds are suggested *if* you have the equipment necessary to individually calibrate and delay each side surround speaker.


In music, and when "remixed for the home" releases are found, all bloody bets are off. There are no standards, each mix engineer does his own thing and we're all clueless as to how to duplicate the mix environment. Certainly personal preference plays a role with respect to what you actually install in your own room. Sometimes it will work well, sometimes not and that is simply because their are no stinkin' standards. (I've seen sound engineers move perfectly set up speakers around the room for his session because "he likes 'em better that way"). Of course, he didn't care what it sounded like in the consumer's environment because the artist or director was going to approve (or not) the mix in the studio, not the home of the guy paying for the recording.


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/20102181
> 
> 
> For surround channels, T Holman hit upon dipoles to simulate the surround _arrays_ used in commercial cinemas. They are to more faithfully reproduce the artist's intent than a single monopole would do in the small space of a home theater.



As you and others have mentioned, the goal was to hear what was heard on the dubbing stage. But dubbing stages and movie theaters are seriously compromised environments, necessarily so, as they have to cover a couple hundred seats in a large room. Our home theaters have the major advantage of a more intimate setting, with a smaller seating area that can be easily covered by high fidelity speakers with good imaging. With proper Erskine-like layout, construction, acoustics, and tuning, the results can far exceed what is heard in a movie theater. Why artificially hamstring it? The theatrical experience is a different animal, and should be celebrated on its own merits--the big feeling, the shared experience with the audience, the sense of occasion. I take nothing away from that. But let the home theater do what it does best without constraints. IMHO. Maybe what we are hearing in our great home theaters is actually what the movie mixer intended, but was prevented from hearing due to the realities of theater sound.


----------



## scl23enn4m3

Hey guys, I need acoustical treatment advice for the back corner of my theater behind a false screen wall. There is a 'nook' with a window at the far end of it. The left side is normal, so I'm just going to put a corner bass trap there, and the rest of the wall will have 2" acoustic foam. What should I do for the nook? It won't be seen so anything is fair game. The window will be covered to prevent light entering.


Here is a picture:










It's about 4' wide. The false wall will start right where that soffit starts. Thanks in advance!


----------



## nathan_h

Other than being worried about covering a wall with two inch acoustic foam (too slender for broadband absorption while too much coverage in that it could over deaden the room) it occurs to me that "nook" could be a giant bass trap, if filled in a way that sound gets in (ie, a fabric false wall) and then you have tons of fiberglass in there....


...I've never really heard or seen such a thing, but that is what occurred to me seeing the photo and hearing your question.


Posting the room layout may help others to answer your question better.


----------



## scl23enn4m3

Thanks for the reply Nathan. So you're thinking just a big box stuffed with fiberglass would be a good way to go? It's a small room...11'W x 16.5'L with 2' of the length taken up by the false wall, plus the nook. Oh and the kicker is the height is 6'2". Here is view from above that I SketchUp-ed up a while back:











The false wall will be completely AT, screen and fabric.


And the 2" foam on the screen wall has been written in pencil. I'd love some advice on what to do with that as well. Thanks again!


----------



## nezff

I think im going with some 2x4x2 panels on the angled ceilings, lower walls, and some 2x2x4 bass traps in the front wall corners. 5 2x4x2 panels on each side of the angled ceiling, 5-6 2x4x4 panels on each side of the lower walls. Bass traps on that short corner behind the front speakers and subs. Not sure exactly what to do with the front wall that will still aesthetically pleasing.


any advice?


----------



## nathan_h




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/0
> 
> 
> Thanks for the reply Nathan. So you're thinking just a big box stuffed with fiberglass would be a good way to go? It's a small room...11'W x 16.5'L with 2' of the length taken up by the false wall, plus the nook. Oh and the kicker is the height is 6'2". Here is view from above that I SketchUp-ed up a while back:
> 
> 
> The false wall will be completely AT, screen and fabric.
> 
> 
> And the 2" foam on the screen wall has been written in pencil. I'd love some advice on what to do with that as well. Thanks again!



That nook looks like a great equipment space....


At the very least i'd go with fiberglass instead of foam. The other concern is that I'd be worried that's too much coverage. I'd mix it up with more diffusion that absorption and focus the absorption on places a mirror test indicates.


----------



## nathan_h




> Quote:
> Originally Posted by *nezff* /forum/post/0
> 
> 
> I think im going with some 2x4x2 panels on the angled ceilings, lower walls, and some 2x2x4 bass traps in the front wall corners. 5 2x4x2 panels on each side of the angled ceiling, 5-6 2x4x4 panels on each side of the lower walls. Bass traps on that short corner behind the front speakers and subs. Not sure exactly what to do with the front wall that will still aesthetically pleasing.
> 
> 
> any advice?



Are these numbers based on the mirror test and that's how many panels you need, in those locations, to cover the first reflection points?


----------



## nezff

No, this would pretty take care of most of the walls and angled ceiling. But will be doing the mirror test.


----------



## nathan_h




> Quote:
> Originally Posted by *nezff* /forum/post/0
> 
> 
> No, this would pretty take care of most of the walls and angled ceiling. But will be doing the mirror test.



That test will be interesting. I'd be worried covering everything.


----------



## nezff




> Quote:
> Originally Posted by *nathan_h* /forum/post/20105781
> 
> 
> That test will be interesting. I'd be worried covering everything.



Im not really covering everything, Im spacing the panels out, but have 30feet to cover.


----------



## scl23enn4m3




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> 
> That nook looks like a great equipment space....
> 
> 
> At the very least i'd go with fiberglass instead of foam. The other concern is that I'd be worried that's too much coverage. I'd mix it up with more diffusion that absorption and focus the absorption on places a mirror test indicates.



I do have plans to place abortive panels where the mirror test/my calculations indicate. I can continue with those panels on my back wall too if you think that's best. I already have enough to do that and it saves me from purchasing the foam. I'm trying to make any panel I make removable. So if I were to make a frame the height and width of the nook, flush to the rest of the wall, how deep should I go? Do I need to treat the back corners of the nook?


----------



## nathan_h




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/0
> 
> 
> 
> I do have plans to place abortive panels where the mirror test/my calculations indicate. I can continue with those panels on my back wall too if you think that's best. I already have enough to do that and it saves me from purchasing the foam. I'm trying to make any panel I make removable. So if I were to make a frame the height and width of the nook, flush to the rest of the wall, how deep should I go? Do I need to treat the back corners of the nook?



Like I said, i've never seen a nook that large used that way, but if it's otherwise lost space I'd put a two or four FOOT thick wall of fiberglass insulation in there, at the front of the opening. Kinda like a giant bank vault door.


In terms of panels, you want some on the front wall and some on the back. Thick fiberglass is best. Rather than fully cover either wall, think about preventing opposing sections of each wall at ear height from both being bare. Example: if you put a panel at head height on the rear wall, you may not need one on the front wall at the same place. This is different from the side walls where you do want parallel coverage at the first reflection points.


Or jus use the mirror method on ALL walls, only place panels in those spots, and you'll be starting from a good base.


Note that there are other opinions too, so i'll step aside and let others jump in.


----------



## scl23enn4m3

Vault door it is. So would the pink stuff be enough? Or do I have to go with something like OC705? And thanks for the information about the front and rear walls. I didn't know the mirror test applied to them too. It does make sense though, so I'll probably just go that route.


I just realize I didn't address the equipment space idea. My equipment is going to be in another room completely. Plus I won't have access to the nook after the screen goes up.


----------



## Ethan Winer




> Quote:
> Originally Posted by *nathan_h* /forum/post/20102304
> 
> 
> Dipole surrounds were really important in the early home cinema days when surround mixes had mono surround channels and/or were the movie theater mixes. The fudging around that dipoles introduced indeed created an envelopement that helped obfuscate the negatives of the technology and process at the time (early 1990s).
> 
> 
> These days, surround mixes have separate discrete (dare I say "stereo") channels, are often mixed and/or equalized for the home video release, and sound most like what the mixer heard when reproduced using direct radiating speakers in a well set up room.



This.


----------



## Ethan Winer




> Quote:
> Originally Posted by *nezff* /forum/post/20105191
> 
> 
> Not sure exactly what to do with the front wall that will still aesthetically pleasing.



I can't address "aesthetically pleasing," but I can tell you what's needed there most are corner bass traps. I see four suitable corners. The main part of that wall may not need anything since your speakers face the other way. More on that here:

Front Wall Absorption 


--Ethan


----------



## vinyl




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/20106375
> 
> 
> Vault door it is. So would the pink stuff be enough? Or do I have to go with something like OC705? And thanks for the information about the front and rear walls. I didn't know the mirror test applied to them too. It does make sense though, so I'll probably just go that route.
> 
> 
> I just realize I didn't address the equipment space idea. My equipment is going to be in another room completely. Plus I won't have access to the nook after the screen goes up.



The nook should remain open to collect the LF – one option similar to treating an open closet is to use several bales of mineral wool stacked floor to ceiling – leaving the bales rolled up in their original plastic wrappers – the nook now becomes one huge trap while still been accessible for whatever.


----------



## scl23enn4m3

Does it matter if there are gaps between the bales? I'm thinking no...but along that route, does it make sense to add corner traps to the back corners of the nook? Or would the bales be sufficient?


----------



## pepar




> Quote:
> Originally Posted by *vinyl* /forum/post/20106461
> 
> 
> The nook should remain open to *collect* the LF - one option similar to treating an open closet is to use several bales of mineral wool stacked floor to ceiling - leaving the bales rolled up in their original plastic wrappers - the nook now becomes one huge trap while still been accessible for whatever.



Collect it?


----------



## vinyl

The bales would be efficient – stacking a couple of bales to corners wouldn’t hurt – the rest could be random spacing is not an issue – the amount of bales is key.


----------



## Teamshenanigans

I completed my acoustic panel project. Room is 25 x 25 with a center ceiling height of 12.5'. The panels are 2" thick (4" in corners) and are floated 2" off the wall. The ones on the side walls are 2x4. The corners are custom built to match the ceiling angle. The largest panels are above the screen and on the rear wall. Bass is much lower and less boomy. The articulation of musical instruments is greatly improved. For movies, the dialogue is easier to understand.


The panels got rid of the echo chamber. Lots of work, but looks and sounds great.


Jamie

Nashville


----------



## nezff

No panels on the angled ceiling?


----------



## Teamshenanigans

No, the wife had to draw the line after 16 large panels







...plus, I didn't want to deaden too much. Seems to sound great right now. Would love to measure it.


jamie


----------



## longshorejl

Can a bass trap be created behind drywall? My backwall is one big closet. I believe the high and mids would bounce off the drywall, but any chance to treat lows behind drywall?


----------



## nezff

Quote:

Originally Posted by *Teamshenanigans* 
No, the wife had to draw the line after 16 large panels







...plus, I didn't want to deaden too much. Seems to sound great right now. Would love to measure it.


jamie
look good though


----------



## Ethan Winer




> Quote:
> Originally Posted by *longshorejl* /forum/post/20115581
> 
> 
> Can a bass trap be created behind drywall?



Not unless you remove the drywall and replace it with something like cardboard.


--Ethan


----------



## studlygoorite

Hey people,


So I just finished my Theater Room and got rid of my two Paradigm 15" Servo Subs and bought a Paradigm Sub 2 to try and acheive better bass. I had things going pretty good until last night, my sump pump broke down during this huge rain storm and my whole basement flooded. The insurance guys are here now sucking up all the water and ripping all the wall to wall carpet out. My question is, should I put a sub floor in to help with bass as the floor is concrete or just go with thick under pad a carpet again? I have read that some say the concrete is good for the bass and also that it is bad and that a sub floor should help. If I do put a sub floor in it can only be 1" thick as the ceiling is not that high to beging with. So what are your guys thoughts, I have to decide by Monday?


Thanks, John


----------



## Johnnycloud

Does it make a big difference if I just set my bass trap up vertically with the base of the trap on the floor in the corners, as opposed to hanging them up in the corner at the mid-wall point?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Johnnycloud* /forum/post/20137441
> 
> 
> Does it make a big difference if I just set my bass trap up vertically with the base of the trap on the floor in the corners, as opposed to hanging them up in the corner at the mid-wall point?



It will be a bit more effective if it hits the tri corners - how much, hard to say - if you can't or just don't want to, you can make up for it with additional bass trapping elsewhere.


----------



## nathan_h




> Quote:
> Originally Posted by *Johnnycloud* /forum/post/20137441
> 
> 
> Does it make a big difference if I just set my bass trap up vertically with the base of the trap on the floor in the corners, as opposed to hanging them up in the corner at the mid-wall point?



No, in fact what you propose is better: The floor/wall/wall location you propose is better than hanging it at the middle of a wall/wall location, that is far away from the floor or ceiling.



> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20138730
> 
> 
> It will be a bit more effective if it hits the tri corners - how much, hard to say - if you can't or just don't want to, you can make up for it with additional bass trapping elsewhere.



Exactly! Since you (Johnnycloud) are proposing a tri corner, you are good to go.


----------



## nathan_h




> Quote:
> Originally Posted by *studlygoorite* /forum/post/20135562
> 
> 
> Hey people,
> 
> 
> So I just finished my Theater Room and got rid of my two Paradigm 15" Servo Subs and bought a Paradigm Sub 2 to try and acheive better bass. I had things going pretty good until last night, my sump pump broke down during this huge rain storm and my whole basement flooded. The insurance guys are here now sucking up all the water and ripping all the wall to wall carpet out. My question is, should I put a sub floor in to help with bass as the floor is concrete or just go with thick under pad a carpet again? I have read that some say the concrete is good for the bass and also that it is bad and that a sub floor should help. If I do put a sub floor in it can only be 1" thick as the ceiling is not that high to beging with. So what are your guys thoughts, I have to decide by Monday?
> 
> 
> Thanks, John



I went with a thin, modest subfloor over my concrete slab, but this was because I wanted hardwood and area rugs on top. The subfloor allowed a little space for air flow and to keep the hardwood from being too firm (a little spring to it).


I'm not sure what I'd do if I was doing wall to wall carpeting -- but I'd be tempted to skip the subfloor except from a moisture/warmth/insulation standpoint.


I can't speak to the acoustics of one scenario versus the other.


----------



## studlygoorite




> Quote:
> Originally Posted by *nathan_h* /forum/post/20139800
> 
> 
> I went with a thin, modest subfloor over my concrete slab, but this was because I wanted hardwood and area rugs on top. The subfloor allowed a little space for air flow and to keep the hardwood from being too firm (a little spring to it).
> 
> 
> I'm not sure what I'd do if I was doing wall to wall carpeting -- but I'd be tempted to skip the subfloor except from a moisture/warmth/insulation standpoint.
> 
> 
> I can't speak to the acoustics of one scenario versus the other.



Well it's plenty warm down there, so if there is no advantage acoustically I'll skip the sub floor.


Thanks


----------



## jcthornton

After reading through all the pages on this thread, I have a few questions and a few conclusions










Conclusions

1. I spent too much time doing that

2. Closing/locking this thread and starting a new one (maybe with the best posts summarized at the start) would be a good thing (and restarting every 100 pages after that)

3. I have huge respect for the many pros (and a lot of the dedicated amateurs) who contribute here


Question

Being at the earliest part of the planning phase (i.e. early education and knowing too many WAF items are in the way of the theater to do it for at least a year) I am trying to educate myself so I can do a full plan up front. Based on couple of items in the intended theater room, I will likely have the space to do some massive superchunk traps. I am contemplating putting in the plans some 4' face traps in each of the front corners.


I would build that by cutting the 2'x4' sheets into 3 pieces - 2 24"x24" [34" face] triangles and 1 34x34 [48" face] triangle. Then alternate layers of the 48" face triangles [face out] with a layer of 2 34" face triangles [face to walls]. That would give me a consistent, fully-filled depth for the superchunk trap. I am assuming that 2 pieces per alternating layer will not impact the effectiveness of the trap.


If I have the math right, 1100/ f = wavelength (l) [in feet]. And these traps are most effective at 1/4 wavelength or deeper. So, if 1/4 l = 2' then f = 1100/8 = 138hz. With less effectiveness as the frequency drops. But we can have some usefulness as low as 1/10 the wavelength [1/10 l = 2'; f = 55 hz] and possibly lower due to edge effects?


Is my understanding and math correct? For a typical ~2500 cubic foot dry-walled rectangular room, this is all a good thing [in addition to more specific treatment as needed for SBIR, early (first) reflections, and slap/flutter echo, comb filtering, etc.]


I am really asking because I have not seen anybody mention doing chunks this big. Conceptually, I cannot think of a reason why this would not be worth doing, it is just an assumption that most people do not have the ability to devote the space for these (only 0.5*3x3x9 = 40 cubic feet







each)


----------



## mtbdudex

My comments in RED your original



> Quote:
> Originally Posted by *jcthornton* /forum/post/20147864
> 
> 
> After reading through all the pages on this thread, I have a few questions and a few conclusions
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Conclusions
> 
> 1. I spent too much time doing that how many hours did it take you?
> 
> 2. Closing/locking this thread and starting a new one (maybe with the best posts summarized at the start) would be a good thing (and restarting every 100 pages after that) 100% agree, I bet many individual avs members have bookmarked pages, we could even have a "Postyour favorite pages" poll to gather that
> 
> 3. I have huge respect for the many pros (and a lot of the dedicated amateurs) who contribute here Agreed
> 
> 
> Question
> 
> Being at the earliest part of the planning phase (i.e. early education and knowing too many WAF items are in the way of the theater to do it for at least a year) I am trying to educate myself so I can do a full plan up front. Based on couple of items in the intended theater room, I will likely have the space to do some massive superchunk traps. I am contemplating putting in the plans some 4' face traps in each of the front corners.
> 
> 
> I would build that by cutting the 2'x4' sheets into 3 pieces - 2 24"x24" [34" face] triangles and 1 34x34 [48" face] triangle. Then alternate layers of the 48" face triangles [face out] with a layer of 2 34" face triangles [face to walls]. That would give me a consistent, fully-filled depth for the superchunk trap. I am assuming that 2 pieces per alternating layer will not impact the effectiveness of the trap.
> 
> 
> If I have the math right, 1100/ f = wavelength (l) [in feet]. And these traps are most effective at 1/4 wavelength or deeper. So, if 1/4 l = 2' then f = 1100/8 = 138hz. With less effectiveness as the frequency drops. But we can have some usefulness as low as 1/10 the wavelength [1/10 l = 2'; f = 55 hz] and possibly lower due to edge effects?
> 
> 
> Is my understanding and math correct? For a typical ~2500 cubic foot dry-walled rectangular room, this is all a good thing [in addition to more specific treatment as needed for SBIR, early (first) reflections, and slap/flutter echo, comb filtering, etc.]
> 
> 
> I am really asking because I have not seen anybody mention doing chunks this big. Conceptually, I cannot think of a reason why this would not be worth doing, it is just an assumption that most people do not have the ability to devote the space for these (only 0.5*3x3x9 = 40 cubic feet
> 
> 
> 
> 
> 
> 
> 
> each)



btw, if you do this your HT shoud be named "The Mega bass superchunk theatre".


----------



## nezff

im debating on either black or white on the angled ceiling? any advice


----------



## CruelInventions

Well, aesthetically speaking, with the lights on, white would look MUCH better since it would better complement your existing color scheme.


With the lights off or dimmed, black is generally the preferred color as it lessens visual distraction. That color wouldn't reflect any light coming off the screen content. However, given the fact that most of your room is already white or a light brown color anyway, there would be somewhat less of a benefit going with black. Depends upon just how many panels you plan to place on that front wall and the ceiling & wall corners. The more you plan on placing there, the stronger a recommendation for going black.


----------



## nezff

I was planning on doing 10 2x4 panels on the angled ceilings and 10 on the lower walls. I am definately doing black on the lower walls. I think the black will go with the seating and other components well. I was planning on doing the white just to match the angled ceiling, but black might look ok?


----------



## CruelInventions

You know, I totally zoned out by not seeing the color of your seating and your front end equipment for that matter.


I suspect black would still be better up there, but let me turn the question back to you...


with your existing white ceiling, when viewing your panel with the lights off or dimmed low, depending upon what your normal lighting scenario is... do you find yourself noticing and being distracted by the white ceiling much, if ever?


If yes, then go black there as well. If not so much and furthermore, you like the idea of white panels to match the white ceiling, go white.


----------



## nezff




> Quote:
> Originally Posted by *CruelInventions* /forum/post/20148544
> 
> 
> You know, I totally zoned out by not seeing the color of your seating and your front end equipment for that matter.
> 
> 
> I suspect black would still be better up there, but let me turn the question back to you...
> 
> 
> with your existing white ceiling, when viewing your panel with the lights off or dimmed low, depending upon what your normal lighting scenario is... do you find yourself noticing and being distracted by the white ceiling much, if ever?
> 
> 
> If yes, then go black there as well. If not so much and furthermore, you like the idea of white panels to match the white ceiling, go white.



lol.


With normal movie watching, the lights will be off, or maybe one set on. I was just wondering if the black would make the room look bad. thats all.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *nezff* /forum/post/20148478
> 
> 
> I was planning on doing 10 2x4 panels on the angled ceilings and 10 on the lower walls. I am definately doing black on the lower walls. I think the black will go with the seating and other components well. I was planning on doing the white just to match the angled ceiling, but black might look ok?



I didn't notice if you're buying them premade or making them - I would go with natural color burlap, it would be close to the wall color, so would tie into the overall color scheme, without standing out so much like black would.


----------



## nezff

yeah, Im probably getting premade, because the cost of the fabric and cellulose panels shipped is so close to getting them made.


Here is the fabric I liked:
http://www.acoustimac.com/index.php/...-the-yard.html 


The Khaki is more green, the stone just doesnt look good. I had pretty much decided on the black on the lower walls, because it looks pretty good. I used my sub grilles as a example. I was really wanting to match, except for the white on the ceiling, but might just do black everywhere.


----------



## nathan_h




> Quote:
> Originally Posted by *jcthornton* /forum/post/20147864
> 
> 
> 2. Closing/locking this thread and starting a new one (maybe with the best posts summarized at the start) would be a good thing (and restarting every 100 pages after that)



I think if you are volunteering, the mods would likely be willing to let you edit and maintain such a post at the start of a new thread. And this one could be locked and point to that new thread. I recommend you make that offer if you are interested in maintaining such a living (as in consistently revised over time) first post/FAQ.


It could definitely help reduce the repetition of topics....


----------



## Brad Horstkotte

Hmm, I don't remember the sample of the Khaki being green - looking on the monitor, I think it would go well with your wall color.


----------



## nezff




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20148764
> 
> 
> Hmm, I don't remember the sample of the Khaki being green - looking on the monitor, I think it would go well with your wall color.



lol. I didnt think so either, until I looked at it in person.


I have every sample color.


----------



## jcthornton




> Quote:
> Originally Posted by *nathan_h* /forum/post/20148756
> 
> 
> I think if you are volunteering, the mods would likely be willing to let you edit and maintain such a post at the start of a new thread. And this one could be locked and point to that new thread. I recommend you make that offer if you are interested in maintaining such a living (as in consistently revised over time) first post/FAQ.
> 
> 
> It could definitely help reduce the repetition of topics....



I like the idea. With as busy as this thread is, I don't know if I can commit the time required for that. However, let me see if I can create a poll that can cull people's favorites from the 7000+ posts made to this thread already. At least I can kick off an effort towards a smaller and consolidated thread.


----------



## pepar

I'll just toss this out there - f you are volunteering, then maybe it would work. But no one else here is interested in taking on work like that. Plus, if you think this thread is big and hard to search, here's one that's 1257 *pages* with 38,000 posts.

http://www.avsforum.com/avs-vb/showt...5421&page=1257


----------



## jcthornton




> Quote:
> Originally Posted by *pepar* /forum/post/20148952
> 
> 
> I'll just toss this out there - f you are volunteering, then maybe it would work. But no one else here is interested in taking on work like that. Plus, if you think this thread is big and hard to search, here's one that's 1257 *pages* with 38,000 posts.
> 
> http://www.avsforum.com/avs-vb/showt...5421&page=1257









































I'm just beginning to work on the theater design. I haven't even begun the education on the equipment (cuz I know it will be easier to change the equipment than the theater!)


Audyssey is an EQ system/device, isn't it? It handles electronically as best as it can what we do not handle physically?


It took me at least a full month to get through the 245 pages here. I don't have 6 months to try to do the same for a single device.


----------



## erkq




> Quote:
> Originally Posted by *nezff* /forum/post/20148625
> 
> 
> lol.
> 
> 
> With normal movie watching, the lights will be off, or maybe one set on. I was just wondering if the black would make the room look bad. thats all.



If you might ever want to convert to a projector, darker is better. Light reflection lights up the screen and kills blacks. Just a thought.


----------



## nezff




> Quote:
> Originally Posted by *erkq* /forum/post/20149094
> 
> 
> If you might ever want to convert to a projector, darker is better. Light reflection lights up the screen and kills blacks. Just a thought.



thats definately not a concern right now, since a PJ is not in my immediate future. lol

Im going for looks as well as function.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *nezff* /forum/post/20148768
> 
> 
> lol. I didnt think so either, until I looked at it in person.
> 
> 
> I have every sample color.



I used to have them all too, maybe I still do - could have sworn the khaki was tan.


----------



## nezff




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20149155
> 
> 
> I used to have them all too, maybe I still do - could have sworn the khaki was tan.



maybe what I meant was, the Khaki held up to my wall looks more like it has green in it.


----------



## pepar




> Quote:
> Originally Posted by *jcthornton* /forum/post/20148989
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm just beginning to work on the theater design. I haven't even begun the education on the equipment (cuz I know it will be easier to change the equipment than the theater!)
> 
> 
> Audyssey is an EQ system/device, isn't it? It handles electronically as best as it can what we do not handle physically?
> 
> 
> It took me at least a full month to get through the 245 pages here. I don't have 6 months to try to do the same for a single device.



General advice: Read the first post, and the last week's worth of post. Try a few basic searches for your subject. Beyond that, drop in and ask; we gave up long time ago beating people up because they asked a question that had been asked a hundred times. You will get smacked if the question you asked is answered in the post DIRECTLY ABOVE YOURS.










Audyssey is a mostly automatic room correction system. It is not a substitute for good theater design, but it will do the best it can with what it finds.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *jcthornton* /forum/post/20148989
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm just beginning to work on the theater design. I haven't even begun the education on the equipment (cuz I know it will be easier to change the equipment than the theater!)
> 
> 
> Audyssey is an EQ system/device, isn't it? It handles electronically as best as it can what we do not handle physically?
> 
> 
> It took me at least a full month to get through the 245 pages here. I don't have 6 months to try to do the same for a single device.



Hopefully, this will help you out a little bit. Don't worry about the equipment...at all...until you have a working plan in place. What I mean by working plan is, where everything fits and goes in the assembly/construction of your theater. Once that is complete, then you can decide which equipment to purchase that meets standards and fits within your budget. I wouldn't even read about any equipment until its time to do so.







If you don't have the time to learn this "stuff" (it took me two years just to feel comfortable enough to design my own theater) then that is where a professional would come into play. The job of a professional is to reduce your learning curve time, likely by years, sift through and highlight the really important "stuff", and to deliver a professional product (we already know where the pitfalls and mistakes are made or have made them in the past ourselves).


----------



## Jim McC

How do I know if my room needs acoustical treatments?


----------



## Kal Rubinson




> Quote:
> Originally Posted by *Jim McC* /forum/post/20150324
> 
> 
> How do I know if my room needs acoustical treatments?



Well, you could describe the room to us but, odds are, you need acoustic treatments. It's sort of "If you have to ask..................."


----------



## Ethan Winer




> Quote:
> Originally Posted by *Jim McC* /forum/post/20150324
> 
> 
> How do I know if my room needs acoustical treatments?



As Kal said / implied, all rooms benefit from acoustic treatment. This short article explains the basics in plain English:

Acoustic Basics 


--Ethan


----------



## bushy81

Hey guys I'm planning on building some bass traps and some absorber panels this weekend with some Ultratel 43kg/m3 insulation. The question I have is for the absorber panels I want to use a blank canvas like what you get from the craft store and modify the frame so I can fit the insulation behind the canvas. Then paint the canvas with a colour that matches the room. Will the painted canvas adversely effect the acoustic properties I'm trying to achieve with the panel?? Main reason for this method is to keep the aesthetic police in my house happy


----------



## Brad Horstkotte

It will affect it, but if they're intended as bass traps, then you may not care about reflecting some of the HF off the painted canvas. Depends on how you're doing as far as need for additional HF absorption in the room.


Check this thread for an alternative if you don't want to lose the HF absorption: http://www.avsforum.com/avs-vb/showthread.php?t=1316623


----------



## nezff

Quote:

Originally Posted by *erkq* 
If you might ever want to convert to a projector, darker is better. Light reflection lights up the screen and kills blacks. Just a thought.
I might just do all black panels.


----------



## bushy81

Ok here are the first measurements from REW with my room as it is atm, the graph is measured at the MLP. As a starting position can i take anything away from this to start thinking about treatments?


----------



## erkq




> Quote:
> Originally Posted by *bushy81* /forum/post/20166383
> 
> 
> Ok here are the first measurements from REW with my room as it is atm, the graph is measured at the MLP. As a starting position can i take anything away from this to start thinking about treatments?



What's up with your 10k - 20k octave? It just DIES. Are you using a calibrated mic? Are your speakers dead above 10kHz? Have you done a loop-back test of your ADC to see how the analog input performs?


----------



## bushy81




> Quote:
> Originally Posted by *erkq* /forum/post/20166591
> 
> 
> What's up with your 10k - 20k octave? It just DIES. Are you using a calibrated mic? Are your speakers dead above 10kHz? Have you done a loop-back test of your ADC to see how the analog input performs?



The problem is I'm using the Radioshack spl meter which doesnt have the real ability to measure accurately above 3khz. I'm waiting for ECM8000 mic but wont have it for a week or so. Should i ignore the measurements above 3khz?


----------



## pepar




> Quote:
> Originally Posted by *bushy81* /forum/post/20166706
> 
> 
> The problem is I'm using the Radioshack spl meter which doesnt have the real ability to measure accurately above 3khz. I'm waiting for ECM8000 mic but wont have it for a week or so. Should i ignore the measurements above 3khz?



You should fuggedibout measuring until the ECM8000 arrives.


----------



## bushy81

no worries tanks


----------



## trek737

Alright since I have now found out that I can not afford acoustic panels that are sold and installed by professionals, I must rely on myself to get this done.


I am going to buy OC703 or OC705 or OC sound board and wrap it with fabric.


Two questions:


1. Does any one have a good recommendations on where to buy the OC and at a fair price?


2. Do I need a special acoustic fabric? If so what do I need and where is a good place to get it?


Thanks for all of your help from this DIY trying to stay with in my budget.


Jim


P.S.


The same can be said for stereo racks. I was looking for Mid Atlantic or an off brand like Strong and getting two 72" racks with custom face plates for all of my components. Just using Strong for the racks which is not the biggest name in the industry, and no custom face plates was well over $4K. Some custom face plates from Mid Atlantic and I was quoted $1800.00. So for around $6K I can have some nice racks. Wow, that is a lot of change for some metal that is not gold or silver.

I love my theater but maybe some money for retirement would be nice too.


----------



## erkq




> Quote:
> Originally Posted by *trek737* /forum/post/20171825
> 
> 
> 1. Does any one have a good recommendations on where to buy the OC and at a fair price?



It depends where you live. Where do you live?


----------



## Brad Horstkotte

Where do you live? The best sources for the fiberglass used in acoustic treatments are local commercial insulation suppliers. Check http://www.bobgolds.com/AbsorptionCoefficients.htm and get familiar with some of the other options, so you can be flexible depending on what's available locally and what the prices are. Owens Corning, Johns Manville, Roxul, Knauf all make good options. Look for 3-6 pounds per cubic foot rigid fiberglass or mineral wool.


Keep an eye on craigslist for used racks - I found a 43u MA Slim5 with some accessories for $180 locally.


----------



## NicksHitachi




> Quote:
> Originally Posted by *trek737* /forum/post/0
> 
> 
> Alright since I have now found out that I can not afford acoustic panels that are sold and installed by professionals, I must rely on myself to get this done.
> 
> 
> I am going to buy OC703 or OC705 or OC sound board and wrap it with fabric.
> 
> 
> Two questions:
> 
> 
> 1. Does any one have a good recommendations on where to buy the OC and at a fair price?
> 
> 
> 2. Do I need a special acoustic fabric? If so what do I need and where is a good place to get it?
> 
> 
> Thanks for all of your help from this DIY trying to stay with in my budget.
> 
> 
> Jim
> 
> 
> P.S.
> 
> 
> The same can be said for stereo racks. I was looking for Mid Atlantic or an off brand like Strong and getting two 72" racks with custom face plates for all of my components. Just using Strong for the racks which is not the biggest name in the industry, and no custom face plates was well over $4K. Some custom face plates from Mid Atlantic and I was quoted $1800.00. So for around $6K I can have some nice racks. Wow, that is a lot of change for some metal that is not gold or silver.
> 
> I love my theater but maybe some money for retirement would be nice too.



check for a spi products in your area, hats where I found mine.


yes it should be covered with A.T. fabric if you want broadband absorption, if you just want to bass trap you cAn use other coverings. I like to use GOM, burlap, or speaker cloth....


yes racks are expensive, you can DIY for cheaper with some ingenuity...... I made this one.......


----------



## CruelInventions




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/20172629
> 
> 
> 
> yes it should be covered with A.T. fabric if you want broadband absorption....



"A.T." for acoustically transparent (fabric).


----------



## yacht422

when putting acoustic treatments on the ceiling, is it best to put (3) 24' X 48",one for each speaker, or would a single 4' X 10' sheet be better.

and how thick for ceiling usage?

thx

walt


----------



## nathan_h




> Quote:
> Originally Posted by *yacht422* /forum/post/0
> 
> 
> when putting acoustic treatments on the ceiling, is it best to put (3) 24' X 48",one for each speaker, or would a single 4' X 10' sheet be better.
> 
> and how thick for ceiling usage?
> 
> thx
> 
> walt



Either one would work, though three separate panels gives you more flexibility for hitting all first reflection points with less overall coverage (ie less likely to over dampen). I say thicker is better though you get benefit from hanging a panel a few inches off the ceiling similar to making the panel that much thicker.


----------



## DIYHomeTheater




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20171919
> 
> 
> Where do you live? The best sources for the fiberglass used in acoustic treatments are local commercial insulation suppliers. Check http://www.bobgolds.com/AbsorptionCoefficients.htm and get familiar with some of the other options, so you can be flexible depending on what's available locally and what the prices are. Owens Corning, Johns Manville, Roxul, Knauf all make good options. Look for 3-6 pounds per cubic foot rigid fiberglass or mineral wool.
> 
> 
> Keep an eye on craigslist for used racks - I found a 43u MA Slim5 with some accessories for $180 locally.



I just found out that Home Depot can special order Owens Corning. You have to go to their 'Pro Desk' and they can give you quote. All HD Pro Desks have an email service as well. You can ask them for quotes via email. My local Home Depot gave the following quote (2" thick, 2'x4'):


703 series 12 per pack @ @$118.88 per pack

705 without FRK or unfaced is $90.06 and it comes in packs of 5

705 FRK, 6 per pack @ $134.62 per pack


Since these are special orders, it will take about a week for delivery. Returns will be subject to a 15% restocking fee. You must order by the 'pack' and not as single panels. Most HD associates are not familiar with this product and do not even know that it can be ordered. It helps if you email the link to the Owens Corning website that provides the specs for the type of material you are looking for.


----------



## pepar




> Quote:
> Originally Posted by *DIYHomeTheater* /forum/post/20192257
> 
> 
> I just found out that Home Depot can special order Owens Corning. You have to go to their 'Pro Desk' and they can give you quote. All HD Pro Desks have an email service as well. You can ask them for quotes via email. My local Home Depot gave the following quote (2" thick, 2'x4'):
> 
> 
> 703 series 12 per pack @ @$118.88 per pack
> 
> 705 without FRK or unfaced is $90.06 and it comes in packs of 5
> 
> 705 FRK, 6 per pack @ $134.62 per pack
> 
> 
> Since these are special orders, it will take about a week for delivery. Returns will be subject to a 15% restocking fee. You must order by the 'pack' and not as single panels. Most HD associates are not familiar with this product and do not even know that it can be ordered. It helps if you email the link to the Owens Corning website that provides the specs for the type of material you are looking for.



The OP should check with SPI before buying. I seem to remember paying ~$80 for the 703 12-pack.


Jeff


----------



## nezff

just ordered 22 2x4x2 acoustic panels in black.


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/20193673
> 
> 
> just ordered 22 2x4x2 acoustic panels in black.



Put them at the first reflection points first .. front wall, sidewalls, rear wall and ceiling (if you can), and then do a lot of listening before adding more.


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/20193692
> 
> 
> Put them at the first reflection points first .. front wall, sidewalls, rear wall and ceiling (if you can), and then do a lot of listening before adding more.



I plan on spacing them out on the lower walls and angled ceiling.


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/20193700
> 
> 
> I plan on spacing them out on the lower walls and angled ceiling.



OK, but it is very easy to over-dampen residential home theaters.


Jeff


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/20193713
> 
> 
> OK, but it is very easy to over-dampen residential home theaters.
> 
> 
> Jeff



ok, now you have me worried. I thought I didnt order enough, but you make me think I have too many. lol My room is very big with alot of echoes.


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/20193723
> 
> 
> ok, now you have me worried. I thought I didnt order enough, but you make me think I have too many. lol My room is very big with alot of echoes.



Not to over-complicate your existence







, but diffusion is an important part of treating most residential-sized home theaters. If you only have absorbers at this point, then just go slow in installing them. Do some listening after each round. Don't worry, be happy.


----------



## bushy81

Hey guys been reading and learning up on acoustics here, online and the 'Acoustic Master Handbook' and have got most things squared away but I'm still slightly confused on room modes. Does anyone have any links or info that explains it differently. I think I'm good with the basics regarding wavelength and room dimensions but how the individual modes effect the in room response has me confused as well as measuring and noticing the individual modes in the measurement software I'm using REW. any help would be good. Cheers


----------



## Ethan Winer




> Quote:
> Originally Posted by *bushy81* /forum/post/20198516
> 
> 
> Does anyone have any links or info that explains it differently.



Try this:

Graphical Mode Calculator 


The description on that page explains a lot more than just how to use the software. Ask any follow-up questions here.


--Ethan


----------



## CruelInventions

Is that program predicated on the assumption of uniformly square or rectangular rooms? In other words, the software wouldn't be of much use to anyone with a listening room that opens up to another room or rooms where there is no means of blocking those other rooms off entirely, i.e, kitchen, dining room, etc.


----------



## pepar

Quote:

Originally Posted by *CruelInventions* 
Is that program predicated on the assumption of uniformly square or rectangular rooms?
You are correct.


----------



## CruelInventions

thought so, thanks for the quick confirm.


----------



## Dennis Erskine

The calculators presume a rectangular room and completely ignore wall impedance.


----------



## pepar

For those of you in Rio Linda, that means the flexibility and ability to absorb sound energy of the WALLS.


Jeff


----------



## NicksHitachi

ok, I'll bite.


what's the general difference between the wall impedances of say a standard 16" OC studded wall and say a bonus room wall which is typically on about 24" centers if it's truss construction? I would assume the larger panels would resonate at lower frequencies, but what does this mean for the acoustics of the room?


----------



## Dennis Erskine




> Quote:
> ok, I'll bite.



Couldn't tell you. Steel or wood framing? Drywall mounted horizontal or vertical? One layer or two ... decoupled or not ... damped or not?


The spreadsheets assume the walls a perfectly reflective (have an infinite impedance -- resistance to sound transmission). That would be nice, but not really real world. So based upon the characteristics of the room and construction (absorption characteristics of the seats you buy as well), some frequencies will pass right through the wall as if it weren't there, some frequencies may be partially absorbed, etc. Here's an inverse example: demo room in a hotel conference room. The length modes (in the middle of the room) did not at all match the predicted. As you moved out of the center of the room, the modal response reasonably matched predicted (with respect to frequency but not amplitude). So what's the deal here? Well, the deal was the doors (double doors) into the room were on the center line of the room and the impedance of the doors to sound transmission was, like, zip. The modal frequencies for the length modes more closely matched the length of the room PLUS the width of the hallway outside the room.


Let's look at it a different way. You build your room, you turn on the subs, go upstairs and you hear the subs .... that is low frequency energy that didn't stay in the room, and since it is not staying in the room, that means that energy is not contributing to modal amplitude.


At the end of the day, your room will have modal response issues. The spreadsheet might reasonably tell you what frequencies they may occur at; but, it won't tell you if it will be an actual problem. So you beat your brains out trying to address a 40Hz predicted mode and after you build the room ... it ain't there or it isn't audible because of other things going on. Oh, and don't give anytime to peaks and nulls that don't show up in the seating positions ... you don't care about a peak or dip which occurs where no one will be seated.


----------



## ox1216

I'm Stressed..... I had an idea to place a light behind the acustic panels I plan on purchasing. BUT I fear that where the junction boxes are, aren't the same as the reflection points. Please don't jump down my throat for asking, BUT how critical is placing the panels in the exact reflection points? If its that important I will scratch the idea. I will not comprimise on sound quality.


-Alan


----------



## erkq




> Quote:
> Originally Posted by *ox1216* /forum/post/20210755
> 
> 
> I'm Stressed..... I had an idea to place a light behind the acustic panels I plan on purchasing. BUT I fear that where the junction boxes are, aren't the same as the reflection points. Please don't jump down my throat for asking, BUT how critical is placing the panels in the exact reflection points? If its that important I will scratch the idea. I will not comprimise on sound quality.
> 
> 
> -Alan



Well, really... getting the first reflection points is kinda the whole point.


----------



## nathan_h




> Quote:
> Originally Posted by *erkq* /forum/post/0
> 
> 
> 
> well, really... Getting the first reflection points is kinda the whole point.



+10


----------



## ox1216




> Quote:
> Originally Posted by *erkq* /forum/post/20210796
> 
> 
> Well, really... getting the first reflection points is kinda the whole point.



Is the best way to determine the 1st reflection points, is using the mirrior technique?


----------



## eiger

Hi Guys -


I'm looking for some additional advice on the proper treatment of my dedicated HT room. Obviously, we "work with what we have" most of the time. My room is asymetrical on the screen wall side. My subs are in the back of the room.


I have 6 GIK 242s lining both side walls, as well as 2 behind the fronts. (see below). While I have a reasonably flat response, (small peak at 40hz). My room decay times are ok, not perfect.


I have a couple of questions regarding the room -


1) With drywalling NOT BEING AN OPTION, what things can I do to cover the brick fireplace with? Do you believe this would be a worthwhile effort to help with room acoustics?

2) What would be more advantagous, putting a couple of bass traps on the back wall behind the cutain, or the back corners?

3) With dual 18" subs, and my speakers, it gets LOUD in the basement. The living room upstairs (pergo floors) has no escape. Short of re-designing the whole room, am I kind of SOL to keep sound in the basement?


----------



## erkq




> Quote:
> Originally Posted by *ox1216* /forum/post/20211089
> 
> 
> Is the best way to determine the 1st reflection points, is using the mirrior technique?



That's what I did. It's a clever, simple and effective method. Just make sure you get the mirror FLAT to the wall. You probably need someone to help you by holding it up. Don't just lean a mirror against the wall. That (obviously) won't be accurate.


----------



## pepar

If you've ever played pool/billiards, you can usually visualize where to place the absorbers.


----------



## ox1216




> Quote:
> Originally Posted by *erkq* /forum/post/20211145
> 
> 
> That's what I did. It's a clever, simple and effective method. Just make sure you get the mirror FLAT to the wall. You probably need someone to help you by holding it up. Don't just lean a mirror against the wall. That (obviously) won't be accurate.



Will do.. I'll get my kids/teenagers to help.


----------



## ox1216

I'm in such an information overload from the net. Can anyone offer a simple acustic panel to purchase.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *ox1216* /forum/post/20211186
> 
> 
> I'm in such an information overload from the net. Can anyone offer a simple acustic panel to purchase.



Try http://gikacoustics.com/ - they can help you determine what you need as well.


----------



## nezff

im trying to figure out how to hang mine from the angled wall/ceiling.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *nezff* /forum/post/20211913
> 
> 
> im trying to figure out how to hang mine from the angled wall/ceiling.



I use various models of Rotofast devices. http://www.rotofast.com/home.htm


----------



## nezff




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/20212006
> 
> 
> I use various models of Rotofast devices. http://www.rotofast.com/home.htm



I have wood backing. those snap on anchors look pretty darn good.


----------



## Speedskater




> Quote:
> Originally Posted by *ox1216* /forum/post/20211089
> 
> 
> Is the best way to determine the 1st reflection points, is using the mirrior technique?



If the wall surface is a little bit shiny, you can use a laser pointer from the listening positions. sort of a reverse mirror technique.

Or a laser carpenter's level.


----------



## erkq




> Quote:
> Originally Posted by *Speedskater* /forum/post/20212144
> 
> 
> If the wall surface is a little bit shiny, you can use a laser pointer from the listening positions. sort of a reverse mirror technique.
> 
> Or a laser carpenter's level.



If the walls are that shiny he's got another problem. A problem that a few gallons of flat paint of the right color could solve! I know there's WAF involved for a lot of setups, though.


----------



## nathan_h




> Quote:
> Originally Posted by *eiger* /forum/post/20211093
> 
> 
> Hi Guys -
> 
> 
> I'm looking for some additional advice on the proper treatment of my dedicated HT room. Obviously, we "work with what we have" most of the time. My room is asymetrical on the screen wall side. My subs are in the back of the room.
> 
> 
> I have 6 GIK 242s lining both side walls, as well as 2 behind the fronts. (see below). While I have a reasonably flat response, (small peak at 40hz). My room decay times are ok, not perfect.
> 
> 
> I have a couple of questions regarding the room -
> 
> 
> 1) With drywalling NOT BEING AN OPTION, what things can I do to cover the brick fireplace with? Do you believe this would be a worthwhile effort to help with room acoustics?



Its location behind you on a side wall may not be a big first reflection spot but you can hang a panel there. It would help with keeping things symmetrical with the other wall's treatment, which is usually a good thing.


I would consider a couple of panels on the first reflection point(s) on the ceiling, especially if you are looking to cover more areas with treatment to reach a desired decay time.



> Quote:
> 2) What would be more advantagous, putting a couple of bass traps on the back wall behind the cutain, or the back corners?



Probably. You reference measurements. If you can share those, that might get you a more informed answer.


> Quote:
> 3) With dual 18" subs, and my speakers, it gets LOUD in the basement. The living room upstairs (pergo floors) has no escape. Short of re-designing the whole room, am I kind of SOL to keep sound in the basement?



Probably.


> Quote:


----------



## ox1216


















> Quote:
> Originally Posted by *erkq* /forum/post/20212285
> 
> 
> If the walls are that shiny he's got another problem. A problem that a few gallons of flat paint of the right color could solve! I know there's WAF involved for a lot of setups, though.



No shinny walls...just your flat paint


----------



## notnyt

http://imgur.com/GimHz.jpg%5B/IMG%5D



I just cut up 96 pieces for a pair of corner traps.


What's the best way to finish the wall mounts so they're not visible behind the fabric?


----------



## Brad Horstkotte

What method are you using to mount your chunks?


I just screwed/liquid nailed 2x2s vertically at 17" each side of the corners, and then stacked up the 17/17/24 triangles up in the space created. Then wrapped speaker cloth around it (panels cover the staples on the side, if you don't have panels, you could cover staples with trim).


----------



## notnyt

Yeah, I guess I'll just have to use trim to hide the staples.


----------



## eiger

nice work notnyt.


Can you share where you got your materials, how you determined cuts etc?


----------



## notnyt




> Quote:
> Originally Posted by *eiger* /forum/post/20213405
> 
> 
> nice work notnyt.
> 
> 
> Can you share where you got your materials, how you determined cuts etc?



I got 4 boxes of OC703 from J&S supply in Long Island City. It's a two hour drive in one direction, but it's the only place around that has it.


Each sheet is 24"x48"x2", so it will take 48 triangles to stack to an 8' ceiling. To get them into triangles, I started by cutting each piece into squares, then cutting the squares from corner to corner. You can see the jig I made for the angle cuts on the table saw.


I just took some pre-treatment measurements. I'm going to see if I have any 8' long one-by to use to staple fabric to. Tomorrow I will end up picking up some fabric and finishing things. Measurements should be posted tonight if I don't fall asleep first.


----------



## notnyt

http://imgur.com/iNB8p.jpg%5B/IMG%5D




http://imgur.com/Yi58p.jpg%5B/IMG%5D


----------



## notnyt

before and after without even re-running audyssey yet.



http://imgur.com/olgWI.png%5B/IMG%5D


----------



## pepar




> Quote:
> Originally Posted by *eiger* /forum/post/20213405
> 
> 
> nice work notnyt.
> 
> 
> Can you share where you got your materials, how you determined cuts etc?


 http://peparsplace.com/pg23.html


----------



## stgdz

Is there any gain in cutting the panels to 12" instead of the standard 24" for the superchunk?


I can't fit the 24"


----------



## pepar

Quote:

Originally Posted by *stgdz* 
Is there any gain in cutting the panels to 12" instead of the standard 24" for the superchunk?


I can't fit the 24"
A loss of performance.


----------



## ratm

Wow, 240 plus pages of this thread. I am in the process of updating some of my HT and was about to pull the trigger on an XPA-3. I am, however, beginning to understand the value of room treatments in a HT system. My wife (and I to a lesser extent), really like the art type panels, ie., these http://www.audimutesoundproofing.com...e-gallery.html or these http://www.auralex.com/sonicprint/ . BUT, I am at a complete loss as to how big to get, where to place them, and how many to get. Is there anywhere that will give me the basic ins and outs of room treatments without getting technical? I am thinking that, at minimum, I would place one each behind my front speakers to the left and right of my TV, but I dont know if I should get 1x1 or 2x4 or whatnot.


Thank you!


----------



## saprano

After finding the first reflection point with the mirror trick, are any more pannels needed along the rest of the wall? The bare wall is about 10' long (theres a door to another room right next to my left speaker which makes it about 14') with the FRP being about 3' to 4' in.


Opposite wall has a large window towards the middle with a soft widow shade.


Also is a hand mirror a good enough to find the FRP? Don't know if i did it right but it seems the FRP for my left speaker is on the frame wall of the door i was talking about. Im worried now!


If it actually is, can i compromise and put the panel a few inches over? (not like i have a choice)


----------



## stgdz




> Quote:
> Originally Posted by *pepar* /forum/post/20214945
> 
> 
> A loss of performance.



So is the 6 pack panel pack of oc 703 the best deal for super chunks? I have looked at mineral wool and it places like grainger and amazon are selling a single sheet for about 60 bucks.


I am not looking in the rite area though for mineral wool.


----------



## notnyt




> Quote:
> Originally Posted by *stgdz* /forum/post/20217289
> 
> 
> So is the 6 pack panel pack of oc 703 the best deal for super chunks? I have looked at mineral wool and it places like grainger and amazon are selling a single sheet for about 60 bucks.
> 
> 
> I am not looking in the rite area though for mineral wool.




Four boxes cost me $200. That's 24 sheets for $200











Also, some LF waterfalls


Here's a waterfall from before.


http://imgur.com/qpTwO.png%5B/IMG%5D



Here's one from after.


http://imgur.com/6oSil.png%5B/IMG%5D


----------



## Felgar

Quite an impact even down low at 20-30 Hz eh? Interesting that the 47hz area seemed unaffected. Could that be from the floor/ceiling interaction perhaps?


----------



## pepar




> Quote:
> Originally Posted by *stgdz* /forum/post/20217289
> 
> 
> So is the 6 pack panel pack of oc 703 the best deal for super chunks? I have looked at mineral wool and it places like grainger and amazon are selling a single sheet for about 60 bucks.
> 
> 
> I am not looking in the rite area though for mineral wool.



I bought the 12-pack of 24" x 48" x 2" 703 for, IIRC, about $80.


----------



## Ethan Winer




> Quote:
> Originally Posted by *ratm* /forum/post/20216073
> 
> 
> My wife (and I to a lesser extent), really like the art type panels, ie., these http://www.audimutesoundproofing.com...e-gallery.html or these http://www.auralex.com/sonicprint/ . BUT, I am at a complete loss as to how big to get, where to place them, and how many to get.



I knowledgeable vendor will answer all of your questions for free as part of the sale.


--Ethan


----------



## saprano




> Quote:
> Originally Posted by *saprano* /forum/post/20216926
> 
> 
> After finding the first reflection point with the mirror trick, are any more pannels needed along the rest of the wall? The bare wall is about 10' long (theres a door to another room right next to my left speaker which makes it about 14') with the FRP being about 3' to 4' in.
> 
> 
> Opposite wall has a large window towards the middle with a soft widow shade.
> 
> 
> Also is a hand mirror a good enough to find the FRP? Don't know if i did it right but it seems the FRP for my left speaker is on the frame wall of the door i was talking about. Im worried now!
> 
> 
> If it actually is, can i compromise and put the panel a few inches over? (not like i have a choice)



Anyone?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *saprano* /forum/post/20216926
> 
> 
> If it actually is, can i compromise and put the panel a few inches over? (not like i have a choice)



Like you said, you don't really have a choice (unless you want to make something really ugly) - you'll miss some of the reflected energy, but catch some of it too.


----------



## vinyl












Option 1 - search for others


----------



## jim19611961



_____________________

|---------------------- |

|---------------------- |

|-----------------------|

|---SP------------SP---| 14

|-----------------------|

|-----------------------|________

---------------------------------------

---------------------------------------

|-----------------------------------

5|----------XX----------------------

F \\------------------------------------

FF \\----------------------------------

FFF \\---------------------------------

FFFF _________________________


My room sorta looks like this with the total length 25'. The ceiling is vaulted, 84" at either end, 103" at the center of the room.


Im getting a rather large peak at both 63 and 80hz using warble tones and a Radio Shack sound level meter. The right from the listener opens into a kitchen. Anyway. I bought 27-Owens Corning 703 2"x24"x48" panels. Surely this is enough material? Stacking the panels 3 deep for 6" deep panels, that gives me 9 panels at 24"x48". Ive been moving them around, first trying 2 in the front corners, 1 to each side of the speakers, 3 to the rear (dead behind and one to each side, and the last one the wall to the left of the listening position. Zero difference as read before and after using my meter.


The 15.5ft width translates to a 73hz wavelength. I really thought I had the problem workable knowing its cause. I even tried putting every panel along the walls of the 15.5 X14 part of the room. No measurable difference.




I dont understand.


Help


----------



## saprano




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20221190
> 
> 
> Like you said, you don't really have a choice (unless you want to make something really ugly) - you'll miss some of the reflected energy, but catch some of it too.



Wouldn't the frequency response be off since the panels won't be even on each side? Only by a few inches i guess.



> Quote:
> Originally Posted by *vinyl* /forum/post/20221387
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Option 1 - search for others



Haha. I don't want to have to keep moving the panel everytime someone needs to get into the room.


Set it and forget it.


----------



## localhost127




> Quote:
> Originally Posted by *Felgar* /forum/post/20219257
> 
> 
> Quite an impact even down low at 20-30 Hz eh? Interesting that the 47hz area seemed unaffected. Could that be from the floor/ceiling interaction perhaps?



possibly SBIR issue?


----------



## localhost127




> Quote:
> Originally Posted by *stgdz* /forum/post/20217289
> 
> 
> So is the 6 pack panel pack of oc 703 the best deal for super chunks? I have looked at mineral wool and it places like grainger and amazon are selling a single sheet for about 60 bucks.
> 
> 
> I am not looking in the rite area though for mineral wool.



the most effective (and cheapest) porous bass trap will be extremely deep corner traps with (uncompressed) light pink fluffy stuff (standard attic insulation, etc).


if you can give up the real estate to make very deep traps (16"+ at least), you will have much better performance and save a hell of a lot of money vs doing OC703 corner chunks. save the OC703 for broadband absorption panels (first order reflections), and use the cheap pink stuff for corner porous bass traps.


----------



## pepar

Really? I've always read that the fluffy pink stuff was not suitable for trapping bass, especially the deeper frequencies.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *pepar* /forum/post/20224355
> 
> 
> Really? I've always read that the fluffy pink stuff was not suitable for trapping bass, especially the deeper frequencies.



Based on the absorption coefficients, seems like it would work nearly as well, not quite as good at the low end, but probably not much different:


Productthicknessdensity125hz250hz500hz1000hz2000hz4000hzNRC703, plain3" (76mm) on wall3.0 pcf (48 kg/m3)0.531.191.211.081.011.041.10Roxul AFB3" (75mm)2.5 pcf (40 kg/m3)0.520.961.181.071.051.051.05OC pink fluffy unfaced3.5" R11 on wall?0.340.851.090.970.971.120.95

Edit: another approach I've seen mentioned as effective is a rigid fiberglass panel straddling the corner, then backfilled with fluffy pink or cotton insulation.


----------



## pepar




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20224540
> 
> 
> Based on the absorption coefficients, seems like it would work nearly as well, not quite as good at the low end, but probably not much different:
> 
> 
> Productthicknessdensity125hz250hz500hz1000hz2000hz4000hzNRC703, plain3" (76mm) on wall3.0 pcf (48 kg/m3)0.531.191.211.081.011.041.10Roxul AFB3" (75mm)2.5 pcf (40 kg/m3)0.520.961.181.071.051.051.05OC pink fluffy unfaced3.5" R11 on wall?0.340.851.090.970.971.120.95



As I read those specs it seems that it starts to fall off just where bass traps are needed most, i.e. below 500Hz where our room modes occur. It is cheap, though, and readily available.


Jeff


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *pepar* /forum/post/20224903
> 
> 
> As I read those specs it seems that it starts to fall off just where bass traps are needed most, i.e. below 500Hz where our room modes occur.
> 
> 
> Jeff



This is true, but also keep in mind that those are for ~3" on wall, vs. the typical depth in a corner absorber - I couldn't find those numbers though. As a rough approximation:


Unfaced 12" on wall 1.14 1.09 1.09 0.99 1.00 1.21 (about what you'd get toward the middle of the absorber).


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/20224903
> 
> 
> As I read those specs it seems that it starts to fall off just where bass traps are needed most, i.e. below 500Hz where our room modes occur. It is cheap, though, and readily available.
> 
> 
> Jeff



That's why he says "extremely deep". The volume is more than twice the usual (square of the depth). So he's giving us a cheap way of doing it, if we "have the real estate" for it. The key is: big.


----------



## Felgar




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20224932
> 
> 
> This is true, but also keep in mind that those are for ~3" on wall, vs. the typical depth in a corner absorber - I couldn't find those numbers though. As a rough approximation:
> 
> 
> Unfaced 12" on wall 1.14 1.09 1.09 0.99 1.00 1.21 (about what you'd get toward the middle of the absorber).



How did you calculate that rough approximation? Is that for the fluffy pink or the 703? I'm specifically wondering about the effectiveness at even lower frequencies (40Hz) for say a 24" deep corner superchunk...


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/20224938
> 
> 
> That's why he says "extremely deep". The volume is more than twice the usual (square of the depth). So he's giving us a cheap way of doing it, if we "have the real estate" for it. The key is: big.



Many of us don't have the space for the 34" face chunk corner trap, and go with the 24" face. And for a lot of us, 2" thick wall-mounted panels are pushing it with 4" being a rare luxury. I can't imagine having 12" of space unless I had a very large space and a blank slate (with a lot of $$$) for the design.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *Felgar* /forum/post/20225317
> 
> 
> How did you calculate that rough approximation? Is that for the fluffy pink or the 703? I'm specifically wondering about the effectiveness at even lower frequencies (40Hz) for say a 24" deep corner superchunk...



The test data provided for the superchunk corner traps is for the 24" x 24" x 34" version. I don't recall seeing data for the 17" x 17" x 24" version that I and so many others have gone with. They do give data for the 2" x 24" panel straddling the corner though ...


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *erkq* /forum/post/20224938
> 
> 
> That's why he says "extremely deep". The volume is more than twice the usual (square of the depth). So he's giving us a cheap way of doing it, if we "have the real estate" for it. The key is: big.



right - when i said 16" deep, i meant as if you were straddling a 16" deep panel... so you cant directly compare the measurements between that and a triangle superchunk (not apples to apples). but you could still do massive corner traps with pink fluffy as well...


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Felgar* /forum/post/20225317
> 
> 
> How did you calculate that rough approximation? Is that for the fluffy pink or the 703? I'm specifically wondering about the effectiveness at even lower frequencies (40Hz) for say a 24" deep corner superchunk...



Oh I guess I wasn't very clear - those are just numbers from Bob Gold's absorption coefficients list - I picked the 12" because that's about how deep a 24" face corner triangle is in the middle - so you'd get roughly that absorption towards the middle, and closer to the previously stated absorption for 3" on the outside edges - well actually 0 at the outside edges.


I wasn't suggesting that we all go build 12" deep absorbers all over the place, just that corner absorbers are deep (mostly).


----------



## localhost127




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20225440
> 
> 
> 
> I wasn't suggesting that we all go build 12" deep absorbers all over the place, just that corner absorbers are deep (mostly).



right - save the dense & expensive stuff (oc703) for broadband panels to treat specular reflections...where you cant take up as much room.


in the corners/boundaries where you wish to place bass traps, the thicker the better. we're working with porous insulation here, whose effectiveness improves as we approach the 1/4wavelength of a particular frequency where particle velocity as at a maximum.


hence, thicker traps == more effective. however, the caveat is as you continue to build thicker and thicker traps, you will want to use less dense material (lower gas flow resistivity)... stack 12x 2" oc703 panels together into a corner (24" thick deep trap, straddled) - and you may find it reflecting more-so than absorbing.


all that money spent on oc703 and it turns out the cheaper material is more effective (as long as you have the real estate for super deep traps).


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20225441
> 
> 
> you could eat up almost an entire box of OC703 for a single corner 34" wide studiotips superchunk --- which would cost almost $90 a corner !



Go price an Auralex MegaLERND.


----------



## notnyt

$90 a corner is worth it to me







After the corner traps, audyssey finally sees all my speakers outputting at the same levels


----------



## pepar




> Quote:
> Originally Posted by *notnyt* /forum/post/20225539
> 
> 
> $90 a corner is worth it to me
> 
> 
> 
> 
> 
> 
> 
> After the corner traps, audyssey finally sees all my speakers outputting at the same levels



I can still vaguely remember my room pre-treatment and pre-Audyssey, and every now and then .. usually when I am listening to music .. I marvel at how natural my system sounds compared to the bad old days. A good system in a well-treated room is a thing of beauty.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20225656
> 
> 
> I can still vaguely remember my room pre-treatment and pre-Audyssey, and every now and then .. usually when I am listening to music .. I marvel at how natural my system sounds compared to the bad old days. A good system in a well-treated room is a thing of beauty.



exactly. what can audyssey do for decay times? that's half the reason for bass traps/treatment -- not just for flat freq response (which some argue can be solved via audyssey) -- but for controlling modal ringing ! audyssey cant do a thing for the signal once it has left the speaker.


edit: and regarding audyssey --- looking at notnyt's original (pre-treated) response:


http://imgur.com/olgWI.png%5B/IMG%5D



what happens to the amp (signal) when it is asked to bump 70hz by +15dB? isn't that putting a hell of a lot of strain on the amp?


----------



## localhost127




> Quote:
> Originally Posted by *notnyt* /forum/post/20225539
> 
> 
> $90 a corner is worth it to me
> 
> 
> 
> 
> 
> 
> 
> After the corner traps, audyssey finally sees all my speakers outputting at the same levels



absolutely. i remember a while back you said you didnt need bass traps because of your already good looking freq response (even down to 20hz!!)...but the modal ringing is being controlled much better now for you i bet, judging from your waterfall plots. do you notice a significant improvement (from your ears) with some of the decay times controlled with the corner chunks now? i wonder if it's more easily noticeable (controlled decay times) with more SPL as in your case (with so many drivers).


of course the $90/corner is worth it (the measurements speak for themselves), but it would have been much cheaper to do the pink fluffy stuff and make super deep traps (especially since you have the room for it, lucky you





















) ... and id be really interested in your case (since you have such good extension down and below 20hz) to see how massively deep cheap/pink fluffy traps would do for you in the 20-30hz region....as the 34"faced super chunks really dont extend out far enough from the boundary to have much of an effect on those long wavelengths


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20225809
> 
> 
> but what can audyssey do for decay times? that's half the reason for bass traps -- not just for flat freq response but for controlling modal ringing !



It helped reduce modal ringing, too. I wouldn't be without my treatments or Audyssey.


----------



## pepar

I don't have comparative data from my untreated room, but I do have a waterfall of just the SVS AS-EQ1 (Audyssey for the subs) and then an Audyssey Pro cal over it. It's nearly worthless for the topic at hand, but ...


----------



## bh285

Slightly off topic, but related for me at least. I ran 1 yard short of FR701 Black GOM while covering my bass traps. Anyone have a spare yard?


Sorry for drifting the topic, but I figure this forum is as close as I can get. Once I get them in place I can post my room eq.


----------



## Felgar




> Quote:
> Originally Posted by *localhost127* /forum/post/20225461
> 
> 
> right - save the dense & expensive stuff (oc703) for broadband panels to treat specular reflections...where you cant take up as much room.
> 
> 
> hence, thicker traps == more effective. however, the caveat is as you continue to build thicker and thicker traps, you will want to use less dense material (lower gas flow resistivity)... stack 12x 2" oc703 panels together into a corner (24" thick deep trap, straddled) - and you may find it reflecting more-so than absorbing.



I will have the opportunity to build either 24x24x34 corners, or even 32x32x45 if I want; I'm just not sure how to predict the performance difference between those options, esspecially in very low frequencies. Although 703 is pretty tough to find, Roxul mineral wool is readily available so I could use that or else fluffy pink... Would be a shame to spend the $$ on the mineral wool only to have it reflecting instead of absorbing!


----------



## Brad Horstkotte

I went with Roxul AFB because it came bpape recommended







and was available locally for about 1/3 the cost of OC 703 - $80 for enough for all four corners (17/17/24 size superchunks). Per the numbers I posted above, the absorption characteristics are pretty close to OC 703. Its about 2.5 lbs/cf density.


----------



## localhost127




> Quote:
> Originally Posted by *Felgar* /forum/post/20226684
> 
> 
> Would be a shame to spend the $$ on the mineral wool only to have it reflecting instead of absorbing!



it was an extreme example


----------



## notnyt




> Quote:
> Originally Posted by *localhost127* /forum/post/20225809
> 
> 
> exactly. what can audyssey do for decay times? that's half the reason for bass traps/treatment -- not just for flat freq response (which some argue can be solved via audyssey) -- but for controlling modal ringing ! audyssey cant do a thing for the signal once it has left the speaker.
> 
> 
> edit: and regarding audyssey --- looking at notnyt's original (pre-treated) response:
> 
> 
> http://imgur.com/olgWI.png%5B/IMG%5D
> 
> 
> 
> what happens to the amp (signal) when it is asked to bump 70hz by +15dB? isn't that putting a hell of a lot of strain on the amp?



audyssey doesn't bump nulls.


----------



## pepar




> Quote:
> Originally Posted by *notnyt* /forum/post/20227388
> 
> 
> audyssey doesn't bump nulls.



Nine dB is the max boost, and that doesn't look like it would have gotten any lift from normalization.


Jeff


----------



## Fatawan

I have attached a graphic of my room as it stands now. The purple boxes are subs--there is a stack of 4 x 15" Rythmik subs in the equipment room shooting through the wall(only way to smooth response to second row of seats), and there are two 15" LMS subs behind the screen. The response is almost perfect in this configuration down to 10Hz, EXCEPT for a sharp 10-15dB null at 20Hz. I can move the null around, up and down a few Hz, and maybe lessen it a bit, by messing with delays and phase, but I can't get rid of it. I know I can move subs around to fix the issue, but I was wondering if there is anything that can be done with treatments so I could keep the current locations. I have OC703 chunks in all corners, 6" in soffits above the front and back, 2" on front and back walls, and 1" at side walls. Can anything be done about a null in the low 20's(which seems to correspond to the length of the room)?


Thanks


----------



## nathan_h




> Quote:
> Originally Posted by *Fatawan* /forum/post/0
> 
> 
> I have attached a graphic of my room as it stands now. The purple boxes are subs--there is a stack of 4 x 15" Rythmik subs in the equipment room shooting through the wall(only way to smooth response to second row of seats), and there are two 15" LMS subs behind the screen. The response is almost perfect in this configuration down to 10Hz, EXCEPT for a sharp 10-15dB null at 20Hz. I can move the null around, up and down a few Hz, and maybe lessen it a bit, by messing with delays and phase, but I can't get rid of it. I know I can move subs around to fix the issue, but I was wondering if there is anything that can be done with treatments so I could keep the current locations. I have OC703 chunks in all corners, 6" in soffits above the front and back, 2" on front and back walls, and 1" at side walls. Can anything be done about a null in the low 20's(which seems to correspond to the length of the room)?
> 
> 
> Thanks



Assuming you have maxed out the number, size and depth of your bass trapping already your other options are to move the subs around or try electronic correction. Electronic correction is not very effective with nulls. I think you need to move the subs unless you have more room for thick traps.


----------



## pepar

I was thinking of suggesting that he moved his seats forward a foot or so. The room is long enough and the seats are currently pretty far from the screen.


Moving them forward might take the seats of of the null. More traps would be good as well; I'll bet that there are some "corners" available. Most people overlook .. heh,heh .. the wall/ceiling corners.


Jeff


----------



## nathan_h

Good ideas, esp moving the seats.


----------



## localhost127

trying to read this thread from the beginning...oh dear.


skipping ahead, has anyone looked at reflecting acoustic energy vs just absorbing it --- at first reflection points?


especially in a situation where you have diffusion on the rear (rear sidewalls) wall...you really need to maintain a lot of acoustic energy for diffusion to work properly. this can generally be done by angling large reflective surfaces (wood) so the reflected/redirected acoustic energy can be sent to the rear of the room to be diffused and provide a late arriving diffused sound-field.


much cheaper than OC703 and you will maintain most of the energy in the room.


of course, and ETC plot will still be required to verify that all early reflections are killed off


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20235596
> 
> 
> I was thinking of suggesting that he moved his seats forward a foot or so. The room is long enough and the seats are currently pretty far from the screen.



it would help to determine if that is the axis/plane for that mode at the trouble frequency...otherwise not much sense to go through the work, no?


edit: or determine if it's a null do to the back wall --- if he could give us measurements of the seating position relative to the rear wall


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20240669
> 
> 
> it would help to determine if that is the axis/plane for that mode at the trouble frequency...otherwise not much sense to go through the work, no?
> 
> 
> edit: or determine if it's a null do to the back wall --- if he could give us measurements of the seating position relative to the rear wall



Due to the rear wall? Nulls are the result of sound reflecting between two (or more) surfaces.


In any case, it looks to me like the first row is at the mid-point on the length axis.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20240714
> 
> 
> Due to the rear wall? Nulls are the result of sound reflecting between two (or more) surfaces.



if he's sitting 1/4wavelength from the rear wall at the trouble freq, then he is in a null.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20240731
> 
> 
> if he's sitting 1/4wavelength from the rear wall at the trouble freq, then he is in a null.



Ah yes, a 3/4 wavelength from the front wall.


----------



## Ethan Winer




> Quote:
> Originally Posted by *localhost127* /forum/post/20240663
> 
> 
> this can generally be done by angling large reflective surfaces (wood) so the reflected/redirected acoustic energy can be sent to the rear of the room to be diffused and provide a late arriving diffused sound-field.



Sure, and that's a common design for the wall angles in recording studio control rooms, such as the studio shown below designed by Wes Lachot. But the angles need to be large, and so do the reflection panels. So if you have 3 or more feet of side-wall to give up, that can work. In a smaller / narrower room absorption makes more sense.


--Ethan


----------



## pepar

How does one determine whether to use 1D or 2D diffusors?


----------



## FOH




> Quote:
> Originally Posted by *localhost127* /forum/post/20240663
> 
> 
> skipping ahead, has anyone looked at reflecting acoustic energy vs just absorbing it --- at first reflection points?
> 
> 
> especially in a situation where you have diffusion on the rear (rear sidewalls) wall...you really need to maintain a lot of acoustic energy for diffusion to work properly. this can generally be done by angling large reflective surfaces (wood) so the reflected/redirected acoustic energy can be sent to the rear of the room to be diffused and provide a late arriving diffused sound-field.




This is one approach that many studios, mastering houses, performance halls, and proscenium theaters use in the architectural stages. The sidewalls form an obtuse angle wrt the front wall, thereby directing energy toward the rear of the space and avoiding the typical sidewall mirror point scenario. Upon redirection, to avoid a slap-back or equivalent, some measure of diffusion or absorption must be employed on the back wall,.. as you stated. It does help the critical band w/clarity, by effectually moving the listener forward toward the source and out of the reverberant field.



Good point


----------



## FOH









Ethan beat me to it


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/20242219
> 
> 
> How does one determine whether to use 1D or 2D diffusors?



I can only tell you my reasoning, which may differ from other opinions. You might also see my * All About Diffusion * video. To my thinking, 1D makes sense on the walls of a room, so you don't "waste" energy sending the diffused sound up toward the ceiling or down at the floor. But on a ceiling 2D makes sense so the sound is scattered in all directions around the room.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20242246
> 
> 
> I can only tell you my reasoning, which may differ from other opinions. You might also see my * All About Diffusion * video. To my thinking, 1D makes sense on the walls of a room, so you don't "waste" energy sending the diffused sound up toward the ceiling or down at the floor. But on a ceiling 2D makes sense so the sound is scattered in all directions around the room.
> 
> 
> --Ethan



Testing 1-2-3 ...


Yes, I have watched your video and just did again. But I am not able to hear much on my cheap computer speakers here at work (or on my very nice 5.1 system on my main computer at home), so I am not able to translate what I hear on your video to my HT space.


Your comments regarding 1D/2D tell me something though.


Thanks,

Jeff


----------



## Fatawan




> Quote:
> Originally Posted by *localhost127* /forum/post/20240669
> 
> 
> it would help to determine if that is the axis/plane for that mode at the trouble frequency...otherwise not much sense to go through the work, no?
> 
> 
> edit: or determine if it's a null do to the back wall --- if he could give us measurements of the seating position relative to the rear wall





> Quote:
> Originally Posted by *pepar* /forum/post/20240714
> 
> 
> Due to the rear wall? Nulls are the result of sound reflecting between two (or more) surfaces.
> 
> 
> In any case, it looks to me like the first row is at the mid-point on the length axis.





> Quote:
> Originally Posted by *localhost127* /forum/post/20240731
> 
> 
> if he's sitting 1/4wavelength from the rear wall at the trouble freq, then he is in a null.





> Quote:
> Originally Posted by *pepar* /forum/post/20240735
> 
> 
> Ah yes, a 3/4 wavelength from the front wall.



Ok--that room plan was not exact in measurements. I forgot how I had to rejigger things a bit as I got some extra room from behind the screen, but I went down and measured again. The front row "heads" are 10' from the back wall, and 18' from the front wall.


----------



## localhost127




> Quote:
> Originally Posted by *Fatawan* /forum/post/20243108
> 
> 
> Ok--that room plan was not exact in measurements. I forgot how I had to rejigger things a bit as I got some extra room from behind the screen, but I went down and measured again. The front row "heads" are 10' from the back wall, and 18' from the front wall.



front wall:










rear wall:


----------



## bjvjs

I posted this yesterday on the normal threads section but this my question is more appropriate here.


Has anyone used the coffee bag acoustic panels from ATS Acoustics? If so what are your impressions? These will be used in my daughters great room which need some acoustic treatment.


The kitchen cabinets are 8-9 feet tall with a 3 in crown molding. There is a 3 foot space between the crown and the ceiling and is about 15 feet wide.


Would there be any benefit to placing several OC 703, 2 inch panels on top of the cabinets facing the ceiling? They would be concealed by the crown molding but any reflections off the ceiling near there may be tamed by the panels.


Any thoughts?


----------



## Fatawan




> Quote:
> Originally Posted by *localhost127* /forum/post/20243703
> 
> 
> front wall:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> rear wall:



Since nothing corresponds to my null, what does it all mean???


----------



## FOH





> Quote:
> Originally Posted by *bjvjs* /forum/post/20246892
> 
> 
> I posted this yesterday on the normal threads section but this my question is more appropriate here.
> 
> 
> Has anyone used the coffee bag acoustic panels from ATS Acoustics? If so what are your impressions? These will be used in my daughters great room which need some acoustic treatment.
> 
> 
> The kitchen cabinets are 8-9 feet tall with a 3 in crown molding. There is a 3 foot space between the crown and the ceiling and is about 15 feet wide.
> 
> 
> Would there be any benefit to placing several OC 703, 2 inch panels on top of the cabinets facing the ceiling? They would be concealed by the crown molding but any reflections off the ceiling near there may be tamed by the panels.
> 
> 
> Any thoughts?



What acoustical ailment are you attempting to cure?


----------



## bjvjs

The room is too live and too much echo. Absorption of the live sound is the goal.


The room is around 900 sq, ft with 12 foor ceilings. The main section is about20 x30 with a dining room to the side. All open. All hardwood floors with 2 large area rugs. So it is basically a T shaped room with alot of hard surfaces in the kitchen portion.


I've used 12 diy 2x4 OC 703 panels in my home theater in my home and they work great. My daughter would like something more modern and artsy possibly for the covering of the panel. That's why I inquired about the coffee bag panels from ats acoustics. There is not alot of available wall space in this room.


There is space above the tall kitchen cabinets and the panels would not have to be covered as they would face upwards towards the ceiling and would be hidden by the crown mold on the upper cabinets. There is about a 3-4 foot gap between the ceilings and the top of the cabinets.


It is difficult to watch movies in their home theater set up here due to the live sounds.


Appreciate any input. Thanks.




Thanks


----------



## nathan_h

Got a few photos and a drawing of the layout? That would help, as would any acoustic measurements you have made.


----------



## abl1207

I am thinking about ordering acoustic treatment room interior package and looking at cdgi and acoustic innovations. Has anyone had experience with either company. I am open to other companies as well. Are they able to accurately design the acoustic treatments based on drawings or would i better off waiting to have the room acoustically tested and then having the treatments designed. My project is a retrofit of an existing room which is approximately 19 by 23. Has anyone tried either companies theater seats.


----------



## Bob Ati.

Hi, I know this topic has been mentioned before in the thread,,,In the front sound stage of a hometheater, does it make since to put a 2" 2'x4' pannel behind a sealed center channel(klipsch rc-64). Are there any issues with treating the center and not the front 2?....my center channels back is around 12" from the front wall...thanks....


----------



## Ethan Winer




> Quote:
> Originally Posted by *abl1207* /forum/post/20251832
> 
> 
> Are they able to accurately design the acoustic treatments based on drawings or would i better off waiting to have the room acoustically tested and then having the treatments designed.



It's not strictly needed to measure a room, and good treatment companies can usually tell you what you need just by looking at a few photos and maybe a floor plan. It really comes down to how much you're willing to spend. If budget is not a concern, then by all means hire a local acoustician to measure your room (or do that yourself). But no matter what is measured, the solution for a room that size and shape is more or less the same - as many corner bass traps as possible, plus absorption at the side-wall and ceiling reflection points. So if cost is a concern, you're better off spending the money you'd pay a consultant on more bass traps and other treatment.


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20254893
> 
> 
> It's not strictly needed to measure a room, and good treatment companies can usually tell you what you need just by looking at a few photos and maybe a floor plan. It really comes down to how much you're willing to spend. If budget is not a concern, then by all means hire a local acoustician to measure your room (or do that yourself). But no matter what is measured, the solution for a room that size and shape is more or less the same - as many corner bass traps as possible, plus absorption at the side-wall and ceiling reflection points.



How about diffusion on the ceiling, especially, and the side walls .. instead of absorption .. with THX Ultra speakers .. and the dispersion control that accompanies that certification?


Jeff


----------



## Dennis Erskine

Quote:

I am thinking about ordering acoustic treatment room interior package and looking at cdgi and acoustic innovations. Has anyone had experience with either company. I am open to other companies as well. Are they able to accurately design the acoustic treatments based on drawings or would i better off waiting to have the room acoustically tested and then having the treatments designed. My project is a retrofit of an existing room which is approximately 19 by 23. Has anyone tried either companies theater seats.
Here's a rendering of a "put it in a truck and ship it for installation" including the seats, fixtures, and carpet (from a different company).


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/20254920
> 
> 
> How about diffusion on the ceiling, especially, and the side walls .. instead of absorption .. with THX Ultra speakers .. and the dispersion control that accompanies that certification?



I have no idea.


-Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20260355
> 
> 
> I have no idea.
> 
> 
> -Ethan



Thanks.


Jeff


----------



## localhost127

copyright © from d'antonio & cox "acoustic absorbers and diffusers"


----------



## pepar

Interesting. I wonder how this design performs with angles of incidence other than zero?


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20267985
> 
> 
> Interesting. I wonder how this design performs with angles of incidence other than zero?



re: a QRD, the high freq cutoff will decrease.


you can explore this with QRDude


----------



## yacht422




> Quote:
> Originally Posted by *pepar* /forum/post/20254920
> 
> how about diffusion on the ceiling, especially, and the side walls .. Instead of absorption .. With thx ultra speakers .. And the dispersion control that accompanies that certification?
> 
> jeff


"sound reproduction: Dr toole: Page 506; _HE SHOWS IN A DRAWING, DIFFUSION_. But, he comments,"optional".

IF I COULD LINK IT TO THIS SITE, I WOULD, BUT, CANNOT DO SO FROM A BOOK. THERE IS A LOT TO BE GLEANED FROM THIS ONE PAGE, AS IT SHOWS POSSIBLE SIDE WALL TREATMENTS, WITH HIS OFT QUOTED COMMENTS THAT FIRST REFLECTION ADSORBTION IS NOT NEEDED, IF THE SPEAKERS ARE OF GOOD CONSTRUCTION.


----------



## rgoolio32

I am filling up my acoustical panels with OC703 and i have four Pardigm ADP3 bipole speakers. I understand that the speakers bounce sound of the walls to create a fuller environmental sound. Does that mean the top panels near the speakers should not be filled with absorption material. Any suggestions? (Attached is a picture of my set up)


-Rahul Gole


----------



## localhost127




> Quote:
> Originally Posted by *yacht422* /forum/post/20271504
> 
> "sound reproduction: Dr toole: Page 506; _HE SHOWS IN A DRAWING, DIFFUSION_. But, he comments,"optional".
> 
> IF I COULD LINK IT TO THIS SITE, I WOULD, BUT, CANNOT DO SO FROM A BOOK. THERE IS A LOT TO BE GLEANED FROM THIS ONE PAGE, AS IT SHOWS POSSIBLE SIDE WALL TREATMENTS, WITH HIS OFT QUOTED COMMENTS *THAT FIRST REFLECTION ADSORBTION IS NOT NEEDED, IF THE SPEAKERS ARE OF GOOD CONSTRUCTION.*



and that is debatable...


the principle behind the reflection-free-zone is to destroy any first order reflections that arrive within ISD-gap (e.g., any reflection above -20dB within 20ms of the original source.) ...


if put diffusion at the first reflection points, you will still have specular reflections arriving within the ISD (even though their intensity will be much lower).


edit: not to mention, saying "diffusion" is a very broad term...as there are a host of variables (design freq, HF cutoff, width of the fins, etc)...so you can't just say "diffusion" as a global/singular term.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20272076
> 
> 
> and that is debatable...



Hence the confusion. Are early lateral reflections good, but first reflections are bad? Are early lateral reflections good if off-axis response is flat, but attenuated?


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20272118
> 
> 
> Hence the confusion. Are early lateral reflections good, but first reflections are bad? Are early lateral reflections good if off-axis response is flat, but attenuated?
> 
> 
> Jeff



i would consider early lateral reflections synonymous with first reflections when in the context of the RFZ.


some philosophies argue they are beneficial, others say otherwise.


----------



## FOH




> Quote:
> Originally Posted by *localhost127* /forum/post/20272642
> 
> 
> i would consider early lateral reflections synonymous with first reflections when in the context of the RFZ.
> 
> *some philosophies argue they are beneficial, others say otherwise*.



I can think of no scenario whereby early lateral reflections are beneficial. They are highly destructive to the very carefully crafted soundstage that has been captured at the recorded event. One example; The recording engineer may have spent days finding the absolutely _ideal_ placement for a stereo mic array. A precise placement to capture the exact balance of the _room acoustic_, to that of the _direct energy_ from the performers. Once achieved, the resultant soundstage and imaging can be holographic.



That said, how can any amount of smearing of those arrival times be beneficial whatsoever?




Thanks


----------



## erkq




> Quote:
> Originally Posted by *FOH* /forum/post/20273326
> 
> 
> That said, how can any amount of smearing of those arrival times be beneficial whatsoever?
> 
> Thanks



This debate is as old as sound reproduction itself. There are two basic schools:


1. Provide a window into an environment crafted by the sound engineer. I think this is what you view as the best and it makes sense with home theater especially. We want the environment the movie creates, not our dinky little theater.


2. Have the performance in your house. This idea was the genesis of the whole Bose 901 direct/reflect speakers and similar ideas. "Get the room involved in creating the acoustic space", is the idea. This is something electrostatics are phenomenal at as well as what most bipole speakers attempt to achieve.


For HT, I come down firmly in your camp. But that doesn't mean there's no benefit to the other. It's all what you want.


----------



## jamin




> Quote:
> Originally Posted by *FOH* /forum/post/20273326
> 
> 
> That said, how can any amount of smearing of those arrival times be beneficial whatsoever?
> 
> 
> 
> 
> Thanks



I know! Like eating at restaurant that allows seasoning to be on the table.










We must, at a minimum, demand three dimensional ETC data embedded as metadata for each recording because only then can we have any hope of recreating the listening environment utilized when the recording was mixed. I forsee a huge business opportunity in automated mechanical acoustic treatment and room reconfiguration mechanisms


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/20273326
> 
> 
> I can think of no scenario whereby early lateral reflections are beneficial. They are highly destructive to the very carefully crafted soundstage that has been captured at the recorded event. One example; The recording engineer may have spent days finding the absolutely _ideal_ placement for a stereo mic array. A precise placement to capture the exact balance of the _room acoustic_, to that of the _direct energy_ from the performers. Once achieved, the resultant soundstage and imaging can be holographic.
> 
> 
> 
> That said, how can any amount of smearing of those arrival times be beneficial whatsoever?
> 
> 
> 
> 
> Thanks



i agree 100%, but i don't have any of my own personal data to prove my case (hence, my neutral comment).


----------



## Dennis Erskine

Quote:

some philosophies argue they are beneficial, others say otherwise
Therein lies the root of the problem. Acoustics is not philosophy.


----------



## localhost127

Quote:

Originally Posted by *Dennis Erskine* 
Therein lies the root of the problem. Acoustics is not philosophy.
until the data support a unified, singular solution, then how else could it be described? (im not arguing any specific case here, im looking for examples/terminology to expand my own understanding/vocabulary).


e.g. how would you describe the different designs regarding control rooms?

thanks,


----------



## FOH

The remainder of the room (after ~20msec), season that what ever's the flavor of the month. However, there exists energy that is integral to the core of the recorded event. Beginning with speaker front diffraction, VER, up to about 20msec, that in the _horizontal_ plane is monumentally important to clarity and sound-staging.


It doesn't take floor to ceiling absorption of these mirror points of the sidewalls, but there is an area of concern..., and addressing it with absorption works. The corresponding points on the ceiling and floor are of importance as well, they do smear the arrival and damage the transient leading edges. But that smearing doesn't seem to contain the spatial characteristics as does the sidewalls.


I fully understand that an all out measured assessment of a space is the ideal, then proceed accordingly. I have a modest measuring capabilities. But most enthusiasts want rules of thumb, etc., quick and dirty. That said, as one of those like minded quick and dirty, I suggest to strongly address ceiling and floor between the LP and the mains. Carefully and with more precision address the sidewalls with selective, yet strongly effective* absorption. After that, any areas left that would benefit from added diffusion, diffuse to taste. Now bass trapping is a given, you've got to damp whatever ringing is present...also, a by product is retaining a measure of balance after the above broadband absorption.


I fully understand a system could benefit from merely diffusion at the normal absorption points, if the space was so suited. I appreciate the arguments. I'm currently experimenting with all my treatments down. I'll continue my exercise, without comment, until I'm certain of what I'm experiencing. It is by no means strictly scientific, and may not benefit anyone but me.




*Angle of incidence must be given consideration



Good luck


----------



## Ethan Winer




> Quote:
> Originally Posted by *erkq* /forum/post/20273502
> 
> 
> 2. Have the performance in your house. This idea was the genesis of the whole Bose 901 direct/reflect speakers and similar ideas. "Get the room involved in creating the acoustic space", is the idea. This is something electrostatics are phenomenal at as well as what most bipole speakers attempt to achieve.



Yes, and whether that's acceptable, and better than no reflections, depends entirely on the size of the room. Large rooms can sound good with reflections. Small rooms, not so good. So any discussion of this stuff _must_ include the size of the room.


--Ethan


----------



## Dennis Erskine




> Quote:
> until the data support a unified, singular solution, then how else could it be described?



My gut response to that is "BS"...but I won't say it. To say it is not science until there is a single answer, single solution, universal answer (42) is horse pucky. Design of aircraft is firmly rooted in science, engineering and physics ... those physics haven't changed since the Wright brothers. The fact the F117, B2, B738, Aerostar, Piper Commanche (critical wing design or laminar flow wing) and Honda Jet look different doesn't mean the physics has changed. It is simply an indication that the designers had different objectives, contraints and materials available to meet a specific application. In the end, they all fly and do a darn good job at what they were designed to do.



> Quote:
> e.g. how would you describe the different designs regarding control rooms?



See above. How many control rooms start out with the same budget, same objectives, same equipment, same dimensions, same wall impedance, same geometry? Answer: None.


The first clue that someone doesn't _understand_ accoustics is when they say "my philosophy is...". As opposed to something like "the science behind doing "A" is ... and the result would be ... There are way, way too many people who have read a bunch of books or articles (likely written by individuals who have a similar lack of understanding), talk with big words using self important attitudes speaking as though their garbage is fact when they haven't spent a day in a research lab or facility.


Rant over.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20276369
> 
> 
> Design of aircraft is firmly rooted in science, engineering and physics ... those physics haven't changed since the Wright brothers. The fact the F117, B2, B738, Aerostar, Piper Commanche (critical wing design or laminar flow wing) and Honda Jet look different doesn't mean the physics has changed. It is simply an indication that the designers had different objectives, contraints and materials available to meet a specific application. In the end, they all fly and do a darn good job at what they were designed to do.



can't you describe that by the term, philosophy? philisophy does not mean the concrete absence of 'science'.

_phi·los·o·phy

   /fɪˈlɒsəfi/ Show Spelled[fi-los-uh-fee] Show IPA

–noun, plural -phies.

1.

the rational investigation of the truths and principles of being, knowledge, or conduct.


4.

the critical study of the basic principles and concepts of a particular branch of knowledge, especially with a view to improving or reconstituting them: the philosophy of science.

5.

a system of principles for guidance in practical affairs._




e.g. while on the subject; SR-71,F117, B2, F22, etc... signal management, LO, ("stealth"), is a generational *philosophy*. you would be the first to debate that definition in that context.



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20276369
> 
> 
> The first clue that someone doesn't _understand_ accoustics is when they say "my philosophy is...". As opposed to something like "the science behind doing "A" is ... and the result would be ... There are way, way too many people who have read a bunch of books or articles (likely written by individuals who have a similar lack of understanding), talk with big words using self important attitudes speaking as though their garbage is fact when they haven't spent a day in a research lab or facility.
> 
> 
> Rant over.



where did anyone say "my philosophy is..." ???

i wasn't debating you - *i was asking you to help fill in the gaps*.


----------



## pepar




> Quote:
> Originally Posted by *FOH* /forum/post/20275793
> 
> 
> The remainder of the room (after ~20msec), season that what ever's the flavor of the month. However, there exists energy that is integral to the core of the recorded event. Beginning with speaker front diffraction, VER, up to about 20msec, that in the _horizontal_ plane is monumentally important to clarity and sound-staging.
> 
> 
> It doesn't take floor to ceiling absorption of these mirror points of the sidewalls, but there is an area of concern..., and addressing it with absorption works. The corresponding points on the ceiling and floor are of importance as well, they do smear the arrival and damage the transient leading edges. But that smearing doesn't seem to contain the spatial characteristics as does the sidewalls.
> 
> 
> I fully understand that an all out measured assessment of a space is the ideal, then proceed accordingly. I have a modest measuring capabilities. But most enthusiasts want rules of thumb, etc., quick and dirty. That said, as one of those like minded quick and dirty, I suggest to strongly address ceiling and floor between the LP and the mains. Carefully and with more precision address the sidewalls with selective, yet strongly effective* absorption. After that, any areas left that would benefit from added diffusion, diffuse to taste. Now bass trapping is a given, you've got to damp whatever ringing is present...also, a by product is retaining a measure of balance after the above broadband absorption.
> 
> 
> I fully understand a system could benefit from merely diffusion at the normal absorption points, if the space was so suited. I appreciate the arguments. I'm currently experimenting with all my treatments down. I'll continue my exercise, without comment, until I'm certain of what I'm experiencing. It is by no means strictly scientific, and may not benefit anyone but me.
> 
> 
> 
> 
> *Angle of incidence must be given consideration
> 
> 
> 
> Good luck



Pls post what changes you make after you process what the differences are in the way your space sounds.


I have been looking at my ceiling first reflection point absorber as well as my rear wall absorber as possible candidates for swapping out to diffusion. I will soon be adding some more SSC bass traps and already fell that my room is too deadened; I am thinking the diffusion at those points and maybe a few others will help.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20279781
> 
> 
> Pls post what changes you make after you process what the differences are in the way your space sounds.
> 
> 
> I have been looking at my ceiling first reflection point absorber as well as my rear wall absorber as possible candidates for swapping out to diffusion. I will soon be adding some more SSC bass traps and already fell that my room is too deadened; I am thinking the diffusion at those points and maybe a few others will help.
> 
> 
> Jeff



keeping the rear wall absorption is important for the low end (to combat nulls at the listening position), but what if you could install diffusion over top of the absorption? i built my 2D PRD diffuser on a large stand (with casters/wheels) so it can be moved around...you could possibly do something like this or find a way to mount diffusers in front of your absorbers.


you could always install a form of plastic or reflective layer on your corner chunks so they do not perform broadband absorption, and reflect a bit of mids/highs back into the room. im not sure how much absorption you ahve at the first reflection points, but you could look at minimizing that (removing sq area of absorption) and then checking/verifying with the ETC graph that you are still not seeing any energy within 20ms or so of the original source the listening position.


or if you do end up installing diffusion on the rear wall (and rear side walls) and your room allows for it, you could install large wooden slats at the first reflection points to redirect the sonic energy towards the back of the room, where it is maintained and then can be diffused.


just some thoughts


----------



## nathan_h

Gik has some square diffusers that allow low end frequencies through, so putting those over a bass trap (like the rear wall in this case) might work. You get high frequency diffusion and low end absorption.


I seem to recall Real Traps had an all-in-one solution that did both diffusion and bass trapping, at one time in one panel, too.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20280040
> 
> 
> keeping the rear wall absorption is important for the low end (to combat nulls at the listening position),



With my absorbers being only 2", how much absorption am I getting below Schroeder Frequency? My room relies upon the approx 29 lineal feet of 17" x 17" x 24" chunk traps for controlling room modes. There is still some ringing, so I am adding approx 23LF more. Present chunks are in the front and the add'l will be in the rear.



> Quote:
> im not sure how much absorption you ahve at the first reflection points, but you could look at minimizing that (removing sq area of absorption) and then checking/verifying with the ETC graph that you are still not seeing any energy within 20ms or so of the original source the listening position.



My absorbers are sized so that they are only as big as they need to be to do the job. However, I have since changed the height of LCR (bringing them very close to ear level), so now they are twice as tall as they need to be. Probab ly what I should consider is to reduce their height, and then mount diffusors above and below them. Presently, there is wall carpet there.


Thanks for your thoughts.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20280550
> 
> 
> With my absorbers being only 2", how much absorption am I getting below Schroeder Frequency? "My room relies upon the approx 29 lineal feet of 17" x 17" x 24" chunk traps for controlling room modes. There is still some ringing, so I am adding approx 23LF more. Present chunks are in the front and the add'l will be in the rear.
> 
> 
> 
> My absorbers are sized so that they are only as big as they need to be to do the job. However, I have since changed the height of LCR (bringing them very close to ear level), so now they are twice as tall as they need to be. Probab ly what I should consider is to reduce their height, and then mount diffusors above and below them. Presently, there is wall carpet there.
> 
> 
> Thanks for your thoughts.
> 
> 
> Jeff



have you taken measurements so you know your specific issues that you need to address? would you mind posting them? (waterfalls + ETC)?



regarding the rear wall, you can calculate what freqs you will be in a null at based on the distance between the listening position and the rear wall (and their multiples). 2" (i assume OC703 or equiv density) is not enough for the rear wall regarding LF. 6" OC703 with a 4-6" air gap would work nicely. if you're combating LF, then you need to have thick (porous) traps protruding far enough from the wall towards the 1/4wavelength of the target frequency for them to be most effective. if you have the space, doing massively thick traps (16"+ thickness) made out of uncompressed cheap pink fluffy-stuff insulation (e.g. attic insulation with low gas flow resistivity) would work wonders. if you could then find a way to mount diffusers in front of the rear wall absorber, i think that would work nicely. but you really need thick absorption on the rear wall to combat the nulls at the listening position.


OC703 is expensive. save it for the broadband absorption to control specular reflections. super thick traps of cheap, pink fluffy stuff could be really effective (even as corner traps -- the deeper you make, the better).


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Presently, there is wall carpet there.



From your descriptions of your room, it wouldn't appear you have too many panels, though making the rear ones thicker would have them act more evenly across a wider range of frequencies.


But that wall carpeting is likely what's leaving the feeling the room is over damped, since it sounds like you have a lot, and it just sucks the air out of recordings without being an effective treatment.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20280736
> 
> 
> have you taken measurements so you know your specific issues that you need to address? would you mind posting them? (waterfalls + ETC)?



My previous measuring was .. not particularly well done. So I bought a new calibrated mic from Herb and have installed the latest build of REW, and am going to take another whack at it. Here is pretty much the only useful graph I generated the last time I used it. Decay times were all consistently around 200ms, but you can see the ringing I want to kill. Next chance I get, I'll do the measuring correctly and post.













> Quote:
> regarding the rear wall, you can calculate what freqs you will be in a null at based on the distance between the listening position and the rear wall (and their multiples). 2" (i assume OC703 or equiv density) is not enough for the rear wall regarding LF. 6" OC703 with a 4-6" air gap would work nicely. if you're combating LF, then you need to have thick (porous) traps protruding far enough from the wall towards the 1/4wavelength of the target frequency for them to be most effective. if you have the space, doing massively thick traps (16"+ thickness) made out of uncompressed cheap pink fluffy-stuff insulation (e.g. attic insulation with low gas flow resistivity) would work wonders. if you could then find a way to mount diffusers in front of the rear wall absorber, i think that would work nicely. but you really need thick absorption on the rear wall to combat the nulls at the listening position.



Ears in the second (money) row are 6' from the rear wall. Room is nominally 21' long. So no nulls at the rear row. Aesthetically, I am not going to put big hunking absorbers on the rear wall, or diffusors in front of what's there now.



> Quote:
> OC703 is expensive.



Not particularly. About three years ago, I bought three "bales" for $80 per bale. Each of those had 12 sheets of 2' x 4' x 2". Here's the project I did at the time. And I have enough to add the next ~22LF of the same size.


Jeff


----------



## localhost127

could you perform the waterfall from 0-300hz? it will give better resolution on the LF ringing issues.



> Quote:
> Originally Posted by *pepar* /forum/post/20281286
> 
> 
> Ears in the second (money) row are 6' from the rear wall. Room is nominally 21' long. *So no nulls at the rear row.* Aesthetically, I am not going to put big hunking absorbers on the rear wall, or diffusors in front of what's there now.



while there may not be an infinite null (judging by your waterfall), the rear wall is still contributing to the overall picture. obviously, things are too complex to reach any conclusion. beefing up your rear wall absorber could help smooth things out, but measuring is the only way to know.



> Quote:
> Not particularly. About three years ago, I bought three "bales" for $80 per bale. Each of those had 12 sheets of 2' x 4' x 2". Here's the project I did at the time. And I have enough to add the next ~22LF of the same size.
> 
> 
> Jeff



well, i suppose 'expensive' is a relative term










you won't be taming much of the sub-30hz ringing with OC703/porous absorption unless it extends out far enough towards the 1/4wavelength...(9+ft !)


fine tuning, it may be time to look into pressure based traps (helmholtz,)


you may want to pick up a copy (or check your local library) of 'acoustic absorbers and diffusers', by d'antonio and cox regarding tuned traps.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20281286
> 
> Here's the project I did at the time.
> 
> Jeff



really nice work on your web page (build, photos, etc)...


----------



## ox1216




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20213090
> 
> 
> What method are you using to mount your chunks?
> 
> 
> I just screwed/liquid nailed 2x2s vertically at 17" each side of the corners, and then stacked up the 17/17/24 triangles up in the space created. Then wrapped speaker cloth around it (panels cover the staples on the side, if you don't have panels, you could cover staples with trim).



I'm a visual learner...by any chance do you have pictures of that?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *ox1216* /forum/post/20284259
> 
> 
> I'm a visual learner...by any chance do you have pictures of that?



But of course


----------



## Felgar

Brad, do you have any pre/post waterfalls on those corner traps?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Felgar* /forum/post/20288282
> 
> 
> Brad, do you have any pre/post waterfalls on those corner traps?



No sorry I don't - as far as bass trapping, I'm putting them in "on blind faith", following Ethan's "no such thing as too many bass traps" advice. After I get carpet in, I'll measure the room and decide what I need to add for decay control, reflections, etc.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20281436
> 
> 
> could you perform the waterfall from 0-300hz? it will give better resolution on the LF ringing issues.
> 
> 
> while there may not be an infinite null (judging by your waterfall), the rear wall is still contributing to the overall picture. obviously, things are too complex to reach any conclusion. beefing up your rear wall absorber could help smooth things out, but measuring is the only way to know.



I am in the process now of tweaking the Audyssey Pro target curve. Next up will be to take some measurements before proceeding with the add'l SSC traps.



> Quote:
> you won't be taming much of the sub-30hz ringing with OC703/porous absorption unless it extends out far enough towards the 1/4wavelength...(9+ft !)



'Tis not bad right now and can only get better with more chunk traps.



> Quote:
> fine tuning, it may be time to look into pressure based traps (helmholtz,)
> 
> 
> you may want to pick up a copy (or check your local library) of 'acoustic absorbers and diffusers', by d'antonio and cox regarding tuned traps.



I don't have the space to install something tuned to ~25Hz, and I think the add'l chunk traps will ice it for me.


For my rear absorber, I might start looking at "abfusion" or at least a very deep diffusor ...


Jeff


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20281480
> 
> 
> really nice work on your web page (build, photos, etc)...



Thanks!


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20288752
> 
> 
> I am in the process now of tweaking the Audyssey Pro target curve. Next up will be to take some measurements before proceeding with the add'l SSC traps.



when you have been taking measurements, are you taking them with audyssey enabled??




> Quote:
> Originally Posted by *pepar* /forum/post/20288752
> 
> 
> 'Tis not bad right now and can only get better with more chunk traps.



?? taming 30hz and below with porous absorption will be marginal unless you have extremely thick/deep traps towards where particle velocity is highest.




> Quote:
> Originally Posted by *pepar* /forum/post/20288752
> 
> 
> I don't have the space to install something tuned to ~25Hz, and I think the add'l chunk traps will ice it for me.



i disagree. tuned traps do not take up that much space at all! on the contrary, it's the porous traps like your corner chunks that require incredible real estate sacrifices to be effective at the frequencies in which you need to tame (20-30hz). that was the point of the suggestion. you want a pressure based trap instead of a velocity trap for those issues in 20-30hz.



> Quote:
> For my rear absorber, I might start looking at "abfusion" or at least a very deep diffusor ...



if you have that much OC703 to continue to do corner chunks, i highly suggest a quick experiment by making some 6" broadband panels for your rear wall (with 4-6" air gap), and taking waterfall plots (0-300hz) for pre/post comparison. it should really help vs the 2" you have now. the rear wall is very important to treat, and should not be overlooked just because it is not a corner/tri-corner.


even a deep diffuser will not be effective at low frequencies -- the waves will just defract around the diffuser and reflect off the rear wall and destructively combine at the listening position to form nulls. heavy absorption on the rear wall is incredibly important! diffusion over top can then be used if required.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20288925
> 
> 
> when you have been taking measurements, are you taking them with audyssey enabled??



I have taken both with and without.


Here is the subwoofer at the MLP without the AS-EQ1 and then with it.




















> Quote:
> ?? taming 30hz and below with porous absorption will be marginal unless you have extremely thick/deep traps towards where particle velocity is highest.
> 
> 
> i disagree. tuned traps do not take up that much space at all! on the contrary, it's the porous traps like your corner chunks that require incredible real estate sacrifices to be effective at the frequencies in which you need to tame (20-30hz). that was the point of the suggestion. you want a pressure based trap instead of a velocity trap for those issues in 20-30hz.



I will re-measure, but there was some flabbiness at 300Hz-400Hz and I mainly wanted to clean that up. Any additional benefit I get at 25Hz would be a bonus. The upper bass overhang seems to obscure detail where the 25Hz ringing doesn't. At least by my ears.


Thanks,

Jeff


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20288925
> 
> 
> if you have that much OC703 to continue to do corner chunks, i highly suggest a quick experiment by making some 6" broadband panels for your rear wall (with 4-6" air gap), and taking waterfall plots (0-300hz) for pre/post comparison. it should really help vs the 2" you have now. the rear wall is very important to treat, and should not be overlooked just because it is not a corner/tri-corner.
> 
> 
> even a deep diffuser will not be effective at low frequencies -- the waves will just defract around the diffuser and reflect off the rear wall and destructively combine at the listening position to form nulls. heavy absorption on the rear wall is incredibly important! diffusion over top can then be used if required.



I will say that when in installed the FRP absorbers, the first to go in was the rear absorber and holy cow, what a difference! In fact that one absorber made the most improvement of any of them.


Jeff


----------



## FOH




> Quote:
> Originally Posted by *localhost127* /forum/post/20288925
> 
> 
> 
> .............heavy absorption on the rear wall is incredibly important! .........



How important would you say it is?


Will you assign a hierarchy of importance to; "heavy absorption on the rear wall"?


What room characteristics*** would you suggest contribute to lessening it's importance, and which characteristics heighten it's importance?




***Obviously, a primary LP in relatively close proximity to the rear wall, creates a scenario whereby the rear wall's impact is significant. However, with all the energy focused toward the rear wall, it does play a substantial role in a room's signature. What other characteristics,...thoughts?




Thanks


----------



## FOH




> Quote:
> Originally Posted by *pepar* /forum/post/20289659
> 
> 
> I will say that when in installed the FRP absorbers, the first to go in was the rear absorber and holy cow, what a difference! In fact that one absorber made the most improvement of any of them.
> 
> 
> Jeff



Jeff,

Very interesting, could you elaborate please?



Thanks


----------



## pepar




> Quote:
> Originally Posted by *FOH* /forum/post/20292439
> 
> 
> Jeff,
> 
> Very interesting, could you elaborate please?
> 
> 
> 
> Thanks



My post from March of '06 - "I happened to add the rear one first and was blown away by the improvement in clarity and imaging of the FRONT speakers. Much improved main/surround integration as well. Next added were the front sides - I already had a rug in room front with the thickest padding I could find - which further improved clarity, imaging and surround integration. Last added was the front ceiling panel which added even more improvement in the same areas."


I will expand on that a bit and say that I remember the upper bass tightening a bit as well. I'd speculate that that was from absorption of the upper bass frequencies and reducing ringing, while the other improvements seem related to removing the smearing effects of the 10ms delay (5' past the MLP to the rear wall and then 5' back to the MLP) of the sound from LCR.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/20292431
> 
> 
> How important would you say it is?
> 
> 
> Will you assign a hierarchy of importance to; "heavy absorption on the rear wall"?
> 
> 
> What room characteristics*** would you suggest contribute to lessening it's importance, and which characteristics heighten it's importance?
> 
> 
> 
> 
> ***Obviously, a primary LP in relatively close proximity to the rear wall, creates a scenario whereby the rear wall's impact is significant. However, with all the energy focused toward the rear wall, it does play a substantial role in a room's signature. What other characteristics,...thoughts?
> 
> 
> 
> 
> Thanks



ok - you caught me there. obviously cannot assign a priority as it depends on measured issues for the particular room/scenario. this is why i was looking for a higher resolution waterfall from pepar (0-300 vs 20-20k).


rephrasing, i'll say from reading back on a lot of threads here recently i think it's somewhat fairly overlooked, especially with such high concentration of knowledge and attention focusing on corner chunks/traps, but not necessarily raising the issues of LF nulls due to front wall SBIR and nulls from real wall reflections (or additional comb-filtering). instead of offering opinion of blindly applying 1" or 2" absorption covering the entire front or rear wall (as ive read -- which can become expensive in the monetary as well as the sonic energy contexts), we should be preaching measurements and attacking particular issues for an individual room with surgical precision.


experimentation regarding LF nulls on the back and front wall can be measured fairly easily (even sometimes by ear), by moving the LP along that axis. i dont have any home theater treatment experience, so im not claiming to offer concrete solutions --- just raising awareness to some herd-mentality of blindly applying treatments without specifically knowing what issues their room is imposing.


...and the more measurements + trial-and-error treatment application, the more the community as a whole can learn through real world examples/implementations.


----------



## FOH

^^^


Good points, I was not trying to "call you out", merely wanting additional info


----------



## Felgar




> Quote:
> Originally Posted by *pepar* /forum/post/20289259
> 
> 
> Here is the subwoofer at the MLP without the AS-EQ1 and then with it.



Does your sub actually produce frequencies up around 150Hz+? Or does that chart include a crossover to your mains? Just curious more than anything...


----------



## erkq




> Quote:
> Originally Posted by *Felgar* /forum/post/20293725
> 
> 
> Does your sub actually produce frequencies up around 150Hz+? Or does that chart include a crossover to your mains? Just curious more than anything...



I'll hazard a guess that that's just the sub. That ugly lumpiness up there is typical when you drive higher frequencies into subs. Mine does that. My IB subs are great to 50 or so and then start bumping around just like that.


----------



## pepar




> Quote:
> Originally Posted by *Felgar* /forum/post/20293725
> 
> 
> Does your sub actually produce frequencies up around 150Hz+? Or does that chart include a crossover to your mains? Just curious more than anything...





> Quote:
> Originally Posted by *erkq* /forum/post/20293927
> 
> 
> I'll hazard a guess that that's just the sub. That ugly lumpiness up there is typical when you drive higher frequencies into subs. Mine does that. My IB subs are great to 50 or so and then start bumping around just like that.



That is only the sub channel (four 12" "tube" subs (Hsu TN-1220HO) arranged in collocated pairs, one in front and the other in the rear). Yes, that is response to 150Hz. LFE content can go to 120Hz before sloping off, so subs should have response up there.


Jeff


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/20294708
> 
> 
> That is only the sub channel (four 12" "tube" subs (Hsu TN-1220HO) arranged in collocated pairs, one in front and the other in the rear). Yes, that is response to 150Hz. LFE content can go to 120Hz before sloping off, so subs should have response up there.
> 
> 
> Jeff



I have 3 stout Dynaudio 100W30XL's (12") woofers in my LCR speakers with a -3dB point of 28Hz. I cross over to them well above that at 40Hz and they seem to keep up fine. I was wondering if that would work because I agree with what you say about 120Hz. In my case, it's OK.


----------



## pepar

You have a sub or subs, too, on the subwoofer channel, right?


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/20294907
> 
> 
> You have a sub or subs, too, on the subwoofer channel, right?



Me? Yes, definitely... shoulda' said that. I have an 8 15" woofer IB. (AE IB15's)


----------



## pepar

If your IB doesn't go to 120Hz, then you are likely losing LFE content as it doesn't get routed to the main channels.


----------



## erkq




> Quote:
> Originally Posted by *pepar* /forum/post/20294973
> 
> 
> If your IB doesn't go to 120Hz, then you are likely losing LFE content as it doesn't get routed to the main channels.



Thanks. I'll check on that. It's been a while since I looked at all this. I remember being able to choose 40Hz, 80Hz and something else. I ran REW and saw no gaps but I should re-check to make sure. It may be just my Pioneer BPD-51 BD player's analog outs so I'm missing the upper LFE on all the other sources. I don't know. Worth looking into. But as it turns out I don't use the theater for anything but Blu-Rays!


----------



## Felgar

Hmm... I see. Good point about LFE content up around 120Hz; never really thought about it in reverse, as I've always been focused on the main LCR crossover point. I guess that's one benefit of having subs in multiple locations; having that would help with reducing localization on those higher frequencies...


----------



## pepar




> Quote:
> Originally Posted by *erkq* /forum/post/20295018
> 
> 
> Thanks. I'll check on that. It's been a while since I looked at all this. I remember being able to choose 40Hz, 80Hz and something else. I ran REW and saw no gaps but I should re-check to make sure. It may be just my Pioneer BPD-51 BD player's analog outs so I'm missing the upper LFE on all the other sources. I don't know. Worth looking into. But as it turns out I don't use the theater for anything but Blu-Rays!



Most (all?) receivers/processors have a low pass filter on the LFE, or are you referring to crossovers on the main channels? Also, you'd need to measure the sub channel only to see it's limits. When combined with the bass management and at least one main channel, you likely wouldn't see any "holes."


Wandering OT for this thread. You can PM me about it if you'd like, or start another thread and PM me the link.


Jeff


----------



## ox1216

Where would be the best place to purchase AAcustic Material (GOM) for my false wall? Also, is velcro a common practice to mount your acustic wrapped material to your false wall?


-Alan


----------



## pepar

Quote:

Originally Posted by *ox1216* 
Where would be the best place to purchase AAcustic Material (GOM) for my false wall? Also, is velcro a common practice to mount your acustic wrapped material to your false wall?


-Alan
If you're using panels with frames for rigidity, then velcro probably wouldn't be strong enough. And even bigger panels with the cloth simply wrapping the fiberglass may sag over time if fastened with velcro.


Jeff


----------



## Brad Horstkotte

Quote:

Originally Posted by *ox1216* 
Where would be the best place to purchase AAcustic Material (GOM) for my false wall? Also, is velcro a common practice to mount your acustic wrapped material to your false wall?


-Alan
As far as where to buy, check jesto's build thread, he's in NoVA and found a good source.


----------



## ox1216

Quote:

Originally Posted by *pepar* 
If you're using panels with frames for rigidity, then velcro probably wouldn't be strong enough. And even bigger panels with the cloth simply wrapping the fiberglass may sag over time if fastened with velcro.


Jeff
Hey Jeff,


what /how would you suggest I wrap/cover my false wall with the acustic material?


-Alan


----------



## ox1216

Quote:

Originally Posted by *Brad Horstkotte* 
As far as where to buy, check jesto's build thread, he's in NoVA and found a good source.
Will do.. thanks


----------



## pepar

Quote:

Originally Posted by *ox1216* 
Hey Jeff,


what /how would you suggest I wrap/cover my false wall with the acustic material?


-Alan
Start here .


Velcro works fine for holding lightweight, GOM-wrapped "covers" in place in construction like this.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *ox1216* /forum/post/20298031
> 
> 
> Hey Jeff,
> 
> 
> what /how would you suggest I wrap/cover my false wall with the acustic material?
> 
> 
> -Alan



what are the particular issues in the room you are looking to address?


----------



## ox1216




> Quote:
> Originally Posted by *localhost127* /forum/post/20298174
> 
> 
> what are the particular issues in the room you are looking to address?


 http://www.avsforum.com/avs-vb/showthread.php?t=1327502 


The above link is my issue.


this link is the recommended solution

http://www.avsforum.com/avs-vb/showthread.php?t=1328092 


What are your thoughts? I got myself in a pickle with my speakers and limited width. But I think the false wall will help a lot. especially when I properly treat it.


-alan


----------



## HDvids4all

I'm getting close to making some bass traps for my rear wall soon, and I keep seeing people mention covering the front face of the traps (4" OC703 minimum) with material to reflect highs and mids so the room doesn't sound too dead.


For my room, I plan on making superchunks in the 2 rear corners, and an additional two or three 4" panels mounted to the wall (one to hide the electrical panel). The brackets on the wall in this older pic are where my rear channels are located in a 7.2 setup (surround speakers are fully enclosed Triad InRoom Omni Golds).

_planned trap locations_










So my question is, is it recommended to face these traps with some material to reflect highs and mids? If so, what type of material should I use for this? I already have a couple boxes of unfaced OC703, so I would be adding the facing after the fact.


I thought I had found a place online that sells just the FSK to add yourself, but I can't seem to find it anymore. I've also heard that 3 mil poly can be used, but I'd like some kind of clarification by others more knowledgeable then myself before I make any decisions.


Thanks in advance.


----------



## localhost127




> Quote:
> Originally Posted by *HDvids4all* /forum/post/20321880
> 
> 
> For my room, I plan on making superchunks in the 2 rear corners, and an additional two or three 4" panels mounted to the wall (one to hide the electrical panel). The brackets on the wall in this older pic are where my rear channels are located in a 7.2 setup (surround speakers are fully enclosed Triad InRoom Omni Golds).



what is the purpose of the 4" panels mounted to the wall?


do you have measurements of the room so you know exactly what issues you need to treat, vs blindly applying treatment?


-freq response

-waterfall plot (0-300hz, 0-500ms)

-ETC for specular reflections


----------



## HDvids4all




> Quote:
> Originally Posted by *localhost127* /forum/post/20326416
> 
> 
> what is the purpose of the 4" panels mounted to the wall?
> 
> 
> do you have measurements of the room so you know exactly what issues you need to treat, vs blindly applying treatment?



Noooope, going blind at the moment. My (limited) understanding is that "you can never have too many bass traps." I'd also be covering the electric panel no matter what the purpose of the room, so I thought I might as well make the coverings functional if it's beneficial. If it's not beneficial in that location, no problem, I can always do something else.


The 4" thickness measurement is just a starting point, I could probably do 6" flat against the wall. Anything larger than that is going to encroach too much into the room, so please keep that in mind.


----------



## pepar

Pointing back to generally universal advice - http://www.avsforum.com/avs-vb/showt...3#post17390783


----------



## amarshonarbangla

Arright first time posting in this thread. Here it goes.


I bought a townhouse a few months ago and have been busy remodeling it. I have one extra 18*15 room which I plan on making the home theater. The problem is, it's completely finished, with carpets, baseboards and crown molding. So how do I soundproof this room? I will greatly appreciate any suggestions. Thanks.


----------



## localhost127




> Quote:
> Originally Posted by *amarshonarbangla* /forum/post/20329519
> 
> 
> Arright first time posting in this thread. Here it goes.
> 
> 
> I bought a townhouse a few months ago and have been busy remodeling it. I have one extra 18*15 room which I plan on making the home theater. The problem is, it's completely finished, with carpets, baseboards and crown molding. So how do I soundproof this room? I will greatly appreciate any suggestions. Thanks.



this thread is related to room acoustics and treatments used to tame particular problems within a room. sound-proofing is completely unrelated. i suggest making a new thread in the main forum: http://www.avsforum.com/avs-vb/forumdisplay.php?f=19 with photos, layouts, budget, etc... but understand you will likely not be able to solve any issues without major construction.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20327165
> 
> 
> Anyone .. I am about to build SSC traps across the back wall/ceiling corner and down a rear wall/corner. I certainly have the option of designing something like this corner detail into it .. is it a good idea to do so?



definitely treat the tri-corners. were you able to post a waterfall (from 0-300hz this time) so we could see finer resolution of the issues in that area?


----------



## localhost127




> Quote:
> Originally Posted by *HDvids4all* /forum/post/20327080
> 
> 
> Noooope, going blind at the moment. My (limited) understanding is that "you can never have too many bass traps." I'd also be covering the electric panel no matter what the purpose of the room, so I thought I might as well make the coverings functional if it's beneficial. If it's not beneficial in that location, no problem, I can always do something else.



for the most part, that's right. but keep your "bass traps" in the corners. long wavelengths won't "see" your traps as they are larger and will just diffract around, but by placing in the corner you are essentially forcing the incident energy through the panel. you can still use broadband absorption on the front wall if that is a first reflection via the surround speakers - but this is to absorb specular reflections - NOT to function as a "bass trap"



> Quote:
> Originally Posted by *HDvids4all* /forum/post/20327080
> 
> 
> The 4" thickness measurement is just a starting point, I could probably do 6" flat against the wall. Anything larger than that is going to encroach too much into the room, so please keep that in mind.



if you are able to take measurements (which should be required before blindly applying treatments), you will be able to play around with location and move towards and away from the rear wall to understand how the response is changing ... due to comb-filtering off the rear wall. 4-6" panels directly behind the listening position would be beneficial.


thick bass traps directly behind the front speakers are sometimes used to cure SBIR (nulls off the front walls), but before blindly applying treatments in this location it would be best to take measurements, play around with placement (listening position and/or speaker placement from the front wall) so you know exactly what and where the issue is.


a $50 mic and Room EQ Wizard will go a long way to understanding what the particular issues are in your room and you can then treat those directly and measure the results. if not, blindly apply as much thick absorption in the corners and tri-corners as possible, and then apply broadband absorption at the first reflection points (side walls, ceiling, rear wall, floor). if you used Room EQ Wizard, you could also perform an ETC and know for sure that your broadband absorption is truly destroying all early reflections in the room (and maybe discover a few other non-obvious places where you are seeing early reflections from).


----------



## HDvids4all




> Quote:
> Originally Posted by *localhost127* /forum/post/20330191
> 
> 
> for the most part, that's right...



Thanks for the detailed info. I actually just went through some of the REW threads over the last few days and ordered a mic, USB sound card, etc. to start playing around with REW while I go through this process.



> Quote:
> Originally Posted by *localhost127* /forum/post/20330191
> 
> 
> thick bass traps directly behind the front speakers are sometimes used to cure SBIR (nulls off the front walls), but before blindly applying treatments in this location it would be best to take measurements, play around with placement (listening position and/or speaker placement from the front wall)...



If you look in my build thread, you'll see I have InWall LCRs for fronts, so moving speakers around isn't much of an option. I have insulation all across the front wall, aligned with the LCR faces, to cut down on sound reflections from my AT screen. Underneath the screen is 6" of insulation at the floor/screen wall corner as well, but other than that I haven't done any other treatments to the room yet.


----------



## localhost127




> Quote:
> Originally Posted by *HDvids4all* /forum/post/20331579
> 
> 
> Thanks for the detailed info. I actually just went through some of the REW threads over the last few days and ordered a mic, USB sound card, etc. to start playing around with REW while I go through this process.





























> Quote:
> Originally Posted by *HDvids4all* /forum/post/20331579
> 
> 
> If you look in my build thread, you'll see I have InWall LCRs for fronts, so moving speakers around isn't much of an option. I have insulation all across the front wall, aligned with the LCR faces, to cut down on sound reflections from my AT screen. Underneath the screen is 6" of insulation at the floor/screen wall corner as well, but other than that I haven't done any other treatments to the room yet.



when you get your mic you can verify with an ETC all specular reflections within 20ms of the original signal that you will need to hunt down and kill. if you have rear surrounds, then you will likely want broadband absorption on those reflections points on the front wall.


----------



## pepar

Anyone .. I am about to build SSC traps across the back wall/ceiling corner and down a rear wall/corner. I certainly have the option of designing something like this corner detail into it .. is it a good idea to do so? All modes are present in the tri-corners.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20332057
> 
> 
> Anyone .. I am about to build SSC traps across the back wall/ceiling corner and down a rear wall/corner. I certainly have the option of designing something like this corner detail into it .. is it a good idea to do so? All modes are present in the tri-corners.



absolutely. i replied above.

you still plan to use oc703 (34" faced) like you did for your other corner traps, ya?

take another waterfall (0-300hz) for pre/post comparison.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20332235
> 
> 
> absolutely. i replied above.
> 
> you still plan to use oc703 (34" faced) like you did for your other corner traps, ya?
> 
> take another waterfall (0-300hz) for pre/post comparison.



Arrghh, sorry, I missed that.


The 703 was/is not faced, and the size is 24" faced triangles, i.e. 17 x 17 x 24, 8 triangles per 24 x 48 sheet. I did not/do not have the space for the 24 x 24 x 34 size.


I am in the process of evaluating my new Onk 5508 in relation to the 885 I just sold. I will be taking many measurements over the next few weeks, but last night was my initial listening session. After having Audyssey MultEQ XT and a Pro calibration for nearly two years, the deficiencies of no room correction were painfully obvious. The bottom end was mush, with bass guitar notes all sounding the same ... until the notes were close to 25Hz where my room has a huge peak.


The treatments in my room remained the same, but the room correction was gone. It is this kind of thing that I want to measure and report on.


Jeff


----------



## smokarz

hi guys, i ran REW last night for my front main speakers, without sub. and it seems i have a couple issues.


1 - null at 80hz

2 - falls off at 10khz


the measurement was done at the listening position, about 10ft away from speakers.


i do have 12 panels of OC 703 2" 24x48 on the side walls and back wall.


could you help me identify the causes, hopefully fix the above issues?


thanks.


----------



## localhost127




> Quote:
> Originally Posted by *smokarz* /forum/post/20335161
> 
> 
> hi guys, i ran REW last night for my front main speakers, without sub. and it seems i have a couple issues.
> 
> 
> 1 - null at 80hz
> 
> 2 - falls off at 10khz
> 
> 
> the measurement was done at the listening position, about 10ft away from speakers.
> 
> 
> i do have 12 panels of OC 703 2" 24x48 on the side walls and back wall.
> 
> 
> could you help me identify the causes, hopefully fix the above issues?
> 
> 
> thanks.




what level of smoothing did you apply to the graphs?

-provide graphs without smoothing

-perform a waterfall plot (0-300hz, 0-1000ms)

-perform an ETC graph measured one speaker at a time


what is the distance from the front speakers to the front wall

what is the distance from the listening position (your head) to the rear wall


your 2" panels are being used as broadband absorption to control specular reflections, but you'll need thick absorption in the corners to assist with room modal issues.


----------



## smokarz




> Quote:
> Originally Posted by *localhost127* /forum/post/20335799
> 
> 
> what level of smoothing did you apply to the graphs?
> 
> -provide graphs without smoothing
> 
> -perform a waterfall plot (0-300hz, 0-1000ms)
> 
> -perform an ETC graph measured one speaker at a time
> 
> 
> what is the distance from the front speakers to the front wall
> 
> what is the distance from the listening position (your head) to the rear wall
> 
> 
> your 2" panels are being used as broadband absorption to control specular reflections, but you'll need thick absorption in the corners to assist with room modal issues.



* smoothing 1/3 octave

* attahced is graph without smoothing

* front speakers are about 6 inches from front wall, and lined up against side walls

* listening position is about 10ft from back wall

* my room is about 13x23x6.5, but not perfectly rectangle. it curve in a bit on the left front, and the back right.


i will run the additional graphs when i get home tonight.


thanks much!


----------



## Felgar




> Quote:
> Originally Posted by *smokarz* /forum/post/20335991
> 
> 
> * front speakers are about 6 inches from front wall, and lined up against side walls



Hmmm; not sure what exactly you mean... Can you snap a pic of the front part of the room?


----------



## smokarz




> Quote:
> Originally Posted by *Felgar* /forum/post/20336207
> 
> 
> Hmmm; not sure what exactly you mean... Can you snap a pic of the front part of the room?



ok, i'll snap some pics tonight.


let me try again.


there's a 6" clearance between back of speakers and front wall.


however, speakers line up against the side walls (no clearance)


----------



## smokarz

here are a few pics of the room.


front left, front right, back left, back right, and speaker distance from wall.


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20340800
> 
> 
> here are a few pics of the room.



Are those home-built speakers? Flush-mount those drivers! The difference is huge! The way you've got those components mounted makes it sound like your speaker is playing into a tube by comparison. Do one speaker and compare. It is a very interesting and obvious difference.


It makes a huge difference especially with the high frequency drivers and even with the woofer.


----------



## smokarz

those are klipsch cornwall speakers.


i am not sure i want to take out the drivers and re-do them.


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20340917
> 
> 
> those are klipsch cornwall speakers.
> 
> 
> i am not sure i want to take out the drivers and re-do them.



How interesting. Those tweeters look like Electrovoice T350's, very popular in the homebuilt crowd. Threw me off.


Yeah... I wouldn't to that kind of surgery to a factory speaker either.


----------



## notnyt




> Quote:
> Originally Posted by *erkq* /forum/post/20340859
> 
> 
> Are those home-built speakers? Flush-mount those drivers! The difference is huge! The way you've got those components mounted makes it sound like your speaker is playing into a tube by comparison. Do one speaker and compare. It is a very interesting and obvious difference.
> 
> 
> It makes a huge difference especially with the high frequency drivers and even with the woofer.



Those are horns. They're not meant to be flush mounted.







:facepalm:


They're also supposed to have response to 20khz, so you may want to send out your crossovers to be rebuilt if they're old, and make sure your HF CD's are still working.


----------



## smokarz

actually, i just replaced them with new crossovers from Bob Crites couple months ago.


i am still troubled with the sharp drop off at 10khz.


----------



## erkq




> Quote:
> Originally Posted by *notnyt* /forum/post/20341130
> 
> 
> Those are horns. They're not meant to be flush mounted.
> 
> 
> 
> 
> 
> 
> 
> :facepalm:
> 
> 
> They're also supposed to have response to 20khz, so you may want to send out your crossovers to be rebuilt if they're old, and make sure your HF CD's are still working.



I don't know what the mid horn is, but that tweeter... I am very familiar with it and it most certainly supports flush mounting. It even came with gaskets for it. :facepalm:


Keeping a horn's flair rate consistent to the mouth is important. I've never understood NOT flush mounting horns. The audible difference is not subtle.


I don't want to pollute this thread anymore so that's all I'll say about this.


----------



## notnyt




> Quote:
> Originally Posted by *erkq* /forum/post/20341226
> 
> 
> I don't know what the mid horn is, but that tweeter... I am very familiar with it and it most certainly supports flush mounting. It even came with gaskets for it. :facepalm:
> 
> 
> Keeping a horn's flair rate consistent to the mouth is important. I've never understood NOT flush mounting horns. The audible difference is not subtle.
> 
> 
> I don't want to pollute this thread anymore so that's all I'll say about this.



I didn't even see the baffle earlier, browsing from a 4" phone screen is awful. If that's a first generation cornwall, which it looks like, the K-77 CD's for the top tweeter were mfr'd by EV. Klipsch sent the remainder back that they didn't use and they were sold as T35s from what I understand.


That's just how they were designed. In the later versions, they switched to flush mounted horns. I wouldn't really mess with the original speakers too much since it will devalue them. Personally I'm glad I sold my Klipsch gear and got something modern








However, those are still good speakers, and the baffle will not affect the sound too badly.


Granted, they have nothing at all to do with his problem. The CD's are probably toast or not hooked up right if you've already replaced the xovers.


You've been listening to 2/3rds of a speaker







How did you not notice? The crossover is rolling off your mid horn around 7khz, and you have nothing above that. Time to look for replacement CDs.


----------



## smokarz

well, i didn't notice the drop off until i ran REW and you pointed it out (over at the MIC) shoot out thread.


i do hear sound coming out of the tweeter, so it seems to be funtioning properly?


shoud i do a close mic measurement? put the mic up against the speaker instead of being 10-12ft away?


----------



## notnyt

You may hear sound coming out of it, but not at the same level of the other tweeters and woofers. You should have a flat response at your listening position.


----------



## smokarz

run a close mic measurement.


the red line is mic a feet away from speaker pointing up.


green is the mic a feet away from speaker pointing directly at speaker.


still can't get a flat response, and drops off at around 12khz.


this is troubling. i will run more test once i get the "lilmic" from mike.


guys, any other ideas?


thanks,


----------



## smokarz

and this is the waterfall graph. not sure what i am looking at.


----------



## notnyt

looks better than before.. what about the other speaker?


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20343474
> 
> 
> run a close mic measurement.
> 
> 
> the red line is mic a feet away from speaker pointing up.
> 
> 
> green is the mic a feet away from speaker pointing directly at speaker.
> 
> 
> still can't get a flat response, and drops off at around 12khz.
> 
> 
> this is troubling. i will run more test once i get the "lilmic" from mike.
> 
> 
> guys, any other ideas?
> 
> 
> thanks,



That looks about right for those tweeters. They are very old and weren't great even in their day. I remember mine were down quite a bit by 15kHz. But that was back in the late 70's so I don't remember exactly. But I do remember I was spurred on to Dynaudio components.


----------



## smokarz




> Quote:
> Originally Posted by *erkq* /forum/post/20343501
> 
> 
> That looks about right for those tweeters. They are very old and weren't great even in their day. I remember mine were down quite a bit by 15kHz. But that was back in the late 70's so I don't remember exactly. But I do remember I was spurred on to Dynaudio components.



really? but why would spec says they go up to 20khz?


not questioning you, just trying to understand what i have.thanks


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20343637
> 
> 
> really? but why would spec says they go up to 20khz?
> 
> 
> not questioning you, just trying to understand what i have.thanks



Was that a "frequency range" spec or "frequency response" spec? Back in the day, "frequency range" was used a lot and has a +/- 10dB spec. Other than that... it's not unusual for specs to lie, especially back then. But from my experience with that tweeter, a "frequency range" spec of 20kHz is a lie too. But your response graph does almost fit in the 20dB range of "frequency range".


----------



## smokarz




> Quote:
> Originally Posted by *notnyt* /forum/post/20343496
> 
> 
> looks better than before.. what about the other speaker?



this is the other (right) speaker, mic pointing at speaker.


edit: i noticed that taking these "close mic" measurements, my null at 80hz is gone. does that mean i have a room issue?


----------



## smokarz




> Quote:
> Originally Posted by *erkq* /forum/post/20343651
> 
> 
> Was that a "frequency range" spec or "frequency response" spec? Back in the day, "frequency range" was used a lot and has a +/- 10dB spec. Other than that... it's not unusual for specs to lie, especially back then. But from my experience with that tweeter, a "frequency range" spec of 20kHz is a lie too. But your response graph does almost fit in the 20dB range of "frequency range".



according to Klipsch website:


FREQUENCY RESPONSE 38Hz-20kHz(+-)5dB


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20343673
> 
> 
> according to Klipsch website:
> 
> 
> FREQUENCY RESPONSE 38Hz-20kHz(+-)5dB



From my experience I would not expect that response. And other's mirror my experience too. I'm not trying to argue the point except save you the time and trouble of looking for solutions elsewhere when it is arguably the tweeter itself. Here's what a knowledgeable fellow has to say, though "drops like a stone above 10kHz" is a little harsh. I also had the T350's he mentions and those fell off at 16kHz.


"The Electro-Voice T-35's response drops like a stone above 10 kHz. There are a large number of variants, some with phase plugs, some without, some larger across the short side of the mouth, some smaller, some with stamped black metal horns, some with an anodized finish and sturdier construction, some with a square ferrite magnet, some with a round alnico; all had a phenolic impregnated fabric diaphragm, which made the output less harsh and grating than many such old-school horn tweeters, and the tinsel leads were easily damaged if access to the diaphragm were necessary (like to replace it). There are T35a's and T35B's, and there was also a T-350 that may be thought of as a somewhat larger and much improved T-35. The T-35 was OEM in the Klipsch corner horns, Belle Klipsch, and La Scala, as well as, I think, the Cornwall, but each T-35 delivered was renamed (K77, if I recall correctly), and tested, and only those with a certain level of response were used, the rest returned. They are actually diffraction horns and provide better dispersion when mounted vertically; nevertheless, they have traditionally been mounted horizontally. Back in the early 1970's, the Dead used a wall of them per side for HF."


----------



## erkq

Here's a discussion of a drop-in tweeter that is supposed to go to 20kHz. Further discussion of the T35's frequency response too: http://www.audiokarma.org/forums/arc.../t-222836.html 


OK... I'll stop now.


----------



## smokarz

thanks for your input erkq,


this should stop me from chasing things that are not there. i guess, if i want more than 10-13khz, i should look at other speakers.


btw, do you actually hear stuff beyond 10khz?


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20343748
> 
> 
> thanks for your input erkq,
> 
> 
> this should stop me from chasing things that are not there. i guess, if i want more than 10-13khz, i should look at other speakers.
> 
> 
> btw, do you actually hear stuff beyond 10khz?



I, personally, do. I've taken care of my ears all my life with hearing protection and/or short exposures to LOUD stuff. At 52 I can still hear to 18kHz! I thought the freq. generator was lying, but I double checked it with a counter. Above 18k my hearing shuts off like there's no slope at all... it's just like a switch.


There is audible content up there... harmonics that add realism to lower pitched sounds. There also can be more accurate spatial information/imaging there because of the shorter wavelengths.


----------



## smokarz

i see. i need to look a bit more are either the APT150 or Crites CT125


----------



## notnyt




> Quote:
> Originally Posted by *smokarz* /forum/post/20343670
> 
> 
> this is the other (right) speaker, mic pointing at speaker.
> 
> 
> edit: i noticed that taking these "close mic" measurements, my null at 80hz is gone. does that mean i have a room issue?



Yes, you have a room issue, i told you like 3x =]


super chunks in corners may help, or a resonator


----------



## Dennis Erskine

Have you had your mic calibrated? What make/model is it. Your HF roll off could be your mic.


----------



## notnyt

He's using an Audyssey mic. They don't roll off 20-25db between 10-20k hz. What he's measuring is accurate, though his earlier graphs showed a much earlier rolloff, his later graphs do not.


----------



## localhost127

here is an absolutely *wonderful* thread that shows just how to utilize the ETC to hunt down early reflections.


if anyone is interested...

i highly suggest reading this thread and noting the effort put in place to take measurements one step at a time throughout the troubleshooting process:

http://www.gearslutz.com/board/bass-...ml#post6098894 


starting at post #48 on page 2 for ETCs,

and most notibly:
http://www.gearslutz.com/board/6145795-post60.html


----------



## smokarz




> Quote:
> Originally Posted by *notnyt* /forum/post/20344625
> 
> 
> He's using an Audyssey mic. They don't roll off 20-25db between 10-20k hz. What he's measuring is accurate, though his earlier graphs showed a much earlier rolloff, his later graphs do not.



that's correct, it's the Audyssey mic that came with the Integra 9.9.


the earlier graph was taken at the listening position, where as the latter graph was taken a feet away from speaker.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *notnyt* /forum/post/20344625
> 
> 
> He's using an Audyssey mic. They don't roll off 20-25db between 10-20k hz. What he's measuring is accurate, though his earlier graphs showed a much earlier rolloff, his later graphs do not.





> Quote:
> Originally Posted by *smokarz* /forum/post/20344795
> 
> 
> that's correct, it's the Audyssey mic that came with the Integra 9.9.



The supplied mics require a calibration correction in the AVR but, as far as I know, such information cannot be supplied to other programs. So, one cannot know the inherent FR of this mic unless one has it independently calibrated.


----------



## erkq




> Quote:
> Originally Posted by *Kal Rubinson* /forum/post/20344880
> 
> 
> The supplied mics require a calibration correction in the AVR but, as far as I know, such information cannot be supplied to other programs. So, one cannot know the inherent FR of this mic unless one has it independently calibrated.



Usually calibrated mics start off with pretty flat response in the first place and have a correction curve to take little bumps out. Assuming the worst case and all of this fall-off is the mic, the correction would have to be pretty extreme and that's unlikely. My LinearX mic is so flat I didn't even bother putting its curve into REW. OTOH, this curve (if it's all due to the mic) looks like a Radio Shack SPL meter!


I really do think it's that tweeter. As I've said, I worked with it a lot back in the day on DIY projects and was finally happy when I moved on to Dynaudio. That curve is pretty much how everyone describes its response.


----------



## Vinculum




> Quote:
> Originally Posted by *localhost127* /forum/post/20344645
> 
> 
> here is an absolutely *wonderful* thread that shows just how to utilize the ETC to hunt down early reflections.
> 
> 
> if anyone is interested...
> 
> i highly suggest reading this thread and noting the effort put in place to take measurements one step at a time throughout the troubleshooting process:
> 
> http://www.gearslutz.com/board/bass-...ml#post6098894
> 
> 
> starting at post #48 on page 2 for ETCs,
> 
> and most notibly:
> http://www.gearslutz.com/board/6145795-post60.html




+1


I've been researching ETC as a tool for treatment choices. That guy methodically documented his steps very well. I also like his modular treatment concepts. I myself have used ETC measurement to discover some spikes spaced apart the same width of my room. Undoubtedly some kind of echo going on. I've been over that forum, but didn't see that thread. There are many acoustic propeller heads over there!










Thanks for sharing..


----------



## smokarz




> Quote:
> Originally Posted by *erkq* /forum/post/20344913
> 
> 
> ....
> 
> I really do think it's that tweeter. As I've said, I worked with it a lot back in the day on DIY projects and was finally happy when I moved on to Dynaudio. That curve is pretty much how everyone describes its response.



i agreed.


the t35/k77 of the 70-80s seem to roll off around 12-13khz, though some latter designs can go up to 16khz.


i will take more measurements when i get another mic in.


----------



## erkq




> Quote:
> Originally Posted by *smokarz* /forum/post/20345017
> 
> 
> i agreed.



I know. Sorry to beat a dead horse. I was responding to Kal.


Keep us posted! I'd be very interested in your results.


----------



## localhost127




> Quote:
> Originally Posted by *Vinculum* /forum/post/20344924
> 
> 
> +1
> 
> 
> I've been researching ETC as a tool for treatment choices. That guy methodically documented his steps very well. I also like his modular treatment concepts. I myself have used ETC measurement to discover some spikes spaced apart the same width of my room. Undoubtedly some kind of echo going on. I've been over that forum, but didn't see that thread. There are many acoustic propeller heads over there!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks for sharing..



exactly. the ETC is probably the most overlooked tool at everyone's disposal










additional resource:
http://www.gearslutz.com/board/studi...c-impulse.html


----------



## smokarz

Quote:

Originally Posted by *notnyt* 
Yes, you have a room issue, i told you like 3x =]


super chunks in corners may help, or a resonator
thanks, i should be able to put in the super chunks in a few weeks.


what is resonator?


----------



## ox1216

Would using LINEACUSTICs to make 2'x4'x2" acustic panels be just as affective as ownes 703?


-Alan


----------



## pepar




> Quote:
> Originally Posted by *ox1216* /forum/post/20346493
> 
> 
> Would using LINEACUSTICs to make 2'x4'x2" acustic panels be just as affective as ownes 703?
> 
> 
> -Alan



Compare the two here -

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## ox1216




> Quote:
> Originally Posted by *pepar* /forum/post/20350312
> 
> 
> Compare the two here -
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm



I have about 200'+ left of the Lineacustic rc 1" according to the chart the Owens is slightly better in 2". If I were to double the Line acustic material to 2" per pannel would that make the performance double?


-Alan


----------



## ox1216

Would it make sense to cover the rear wall of my dedicated HT with Lineacustic? or is that over kill?


-Alan


----------



## pepar




> Quote:
> Originally Posted by *ox1216* /forum/post/20350972
> 
> 
> I have about 200'+ left of the Lineacustic rc 1" according to the chart the Owens is slightly better in 2". If I were to double the Line acustic material to 2" per pannel would that make the performance double?
> 
> 
> -Alan



For 2" you should look at the 2" line of specs.


----------



## pepar




> Quote:
> Originally Posted by *ox1216* /forum/post/20350994
> 
> 
> Would it make sense to cover the rear wall of my dedicated HT with Lineacustic? or is that over kill?
> 
> 
> -Alan



Overkill, I think. How close is your seating to the rear wall?


----------



## ox1216




> Quote:
> Originally Posted by *pepar* /forum/post/20351018
> 
> 
> Overkill, I think. How close is your seating to the rear wall?



7 feet


----------



## smokarz




> Quote:
> Originally Posted by *localhost127* /forum/post/20345337
> 
> 
> exactly. the ETC is probably the most overlooked tool at everyone's disposal
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> additional resource:
> http://www.gearslutz.com/board/studi...c-impulse.html



sorry, but what is ETC and what does it do exactly?


----------



## localhost127




> Quote:
> Originally Posted by *smokarz* /forum/post/20351916
> 
> 
> sorry, but what is ETC and what does it do exactly?





> Quote:
> *The ETC provides a total picture of the specular response in the room - from early arrivals to the 'last' of the energy, be it totally damped or a decaying diffuse soundfield. And this is all done with respect to time.
> 
> 
> The ETC allows you to see exactly what kind of energy distribution you have currently, and allows you to select and precisely place the treatment you have chosen in order to create the effect you desire - be it damping, redirection, or diffusion. It also allows you, upon repeating the measurement, to see the precise impact the positioning of the chosen type of treatment has. from this you may be satisfied, or you may want to further refine the positioning in order to insure the proper response is accomplished.*



in brief, it is a measurement of sonic energy versus time. however, it is frequency independent.


it can be used to identify early specular reflections (indirect specular energy paths) - that arrive at your ears after the original signal. since the shortest path between two points is a straight line, the original signal from the speaker to your ears will always arrive first. reflections off side walls, ceiling, etc will always travel a longer distance/path than the original signal, and thus arrive shortly after the original signal reaches your ears.


since we know the speed of sound, by determining via ETC how long after the original signal the reflection arrives at your ears/microphone, one can work backwards to determine the total distance traveled by that specular energy, and thus identify the boundary or object of which the early reflection is incident from. if the room model is to create a reflection free zone (destroy all reflections above -20dB arriving within 20ms of the original signal), then you would use the ETC to discover these early reflections, calculate the distance the path traveled, and identify the boundary that is causing the reflection, and treat that area as appropriate.


one would then *test again* after applying treatment, to verify that the early reflection has truly been attenuated.


the ETC also displays the decay trail (since it is measuring total specular sonic energy).

http://www.google.com/images?hl=en&b...&aqi=&aql=&oq= 


and i'd suggest this thread for additional reading and understanding:
http://www.gearslutz.com/board/studi...c-impulse.html 


edit:


http://imgur.com/IrAIa.jpg%5B/IMG%5D


----------



## pepar




> Quote:
> Originally Posted by *ox1216* /forum/post/20351893
> 
> 
> 7 feet



You could put 2" - 4" of the Linacoustic on the back wall as a first reflection absorber, but you should size is only big enough to cover the first reflections from each of the front speakers to each of the ears in the main listening area. You could do the mirror thing or if you play billiards, simply visualize the lines and angles.


Jeff


----------



## studlygoorite

Anyone ever dealt with Ready Acoustics? I ordered 4 bass trap bags from them 3 months ago. Initially I was told a week to a month and have checked in periodically with them with a reply of we should have some info. soon. They were quick enough to take my money off my Visa. My bass traps have been taking up space for this long and I wonder if they will ever ship my order. Maybe they should change their name to Not Quite Ready And May Never Be Acoustics.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *studlygoorite* /forum/post/20354625
> 
> 
> Anyone ever dealt with Ready Acoustics? I ordered 4 bass trap bags from them 3 months ago. Initially I was told a week to a month and have checked in periodically with them with a reply of we should have some info. soon. They were quick enough to take my money off my Visa. My bass traps have been taking up space for this long and I wonder if they will ever ship my order. Maybe they should change their name to Not Quite Ready And May Never Be Acoustics.



I had a similar experience but they did eventually come through.


----------



## Elill

Quick question on testing gear.


I am getting together the stuff I need to start making reasonable measurements. I've got a calibrated mic on the way from Cross Spectrum, now need an external soundcard. Everyone seems to have their favourites and they all "work", but which one or two are "good"?


Various Soundblaster options?


M-Audio "Audiophile"?


Behringer UCA202?


EMU? no sure which model


TASCAM US-144MKII?


Anything else?


----------



## pepar

I used a Creative Labs for a while but decided to up my game, and my mic from Cross Spectrum requires phantom power. I bought the M-Audio MobilePre, but it was finicky (or maybe it was me), so I sold it and bought the Tascam 122. I'll be using that tonight for the first time, but I have read only good things about it.


Jeff


----------



## Ethan Winer




> Quote:
> Originally Posted by *studlygoorite* /forum/post/20354625
> 
> 
> I wonder if they will ever ship my order.



You're not the only one:

http://www.gearslutz.com/board/6581741-post8.html 


--Ethan


----------



## pepar




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20358352
> 
> 
> You're not the only one:
> 
> http://www.gearslutz.com/board/6581741-post8.html
> 
> 
> --Ethan



He's got more patience than I do ... a LOT more.


Jeff


----------



## studlygoorite




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20358352
> 
> 
> You're not the only one:
> 
> http://www.gearslutz.com/board/6581741-post8.html
> 
> 
> --Ethan



The link does not work for me.


----------



## Ethan Winer




> Quote:
> Originally Posted by *studlygoorite* /forum/post/20359612
> 
> 
> The link does not work for me.



I linked to a single post, and apparently the poster just deleted it. Fortunately, Pepar chimed in and quoted the post in full, so it's still visible:

http://www.gearslutz.com/board/bass-...-business.html 


--Ethan


----------



## pepar

Quote:

Originally Posted by *studlygoorite* 
Anyone ever dealt with Ready Acoustics? I ordered 4 bass trap bags from them 3 months ago. Initially I was told a week to a month and have checked in periodically with them with a reply of we should have some info. soon. They were quick enough to take my money off my Visa. My bass traps have been taking up space for this long and I wonder if they will ever ship my order. Maybe they should change their name to Not Quite Ready And May Never Be Acoustics.
Would appreciate an update when available. I got jumped all over with emails to my _private_ email addresses by the CEO of this company. He made wild accusations about me and my "goal." I told him I had no goal and only had given sound advice to someone who had waited six months with no product to show after having paid in full. Now the mod has deleted my post and has closed the thread. Apparently truth-telling and consumer advocacy is a violation of some rule over there.


Jeff


----------



## studlygoorite




> Quote:
> Originally Posted by *pepar* /forum/post/20361626
> 
> 
> Would appreciate an update when available. I got jumped all over with emails to my _private_ email addresses by the CEO of this company. He made wild accusations about me and my "goal." I told him I had no goal and only had given sound advice to someone who had waited six months with no product to show after having paid in full. Now the mod has deleted my post and has closed the thread. Apparently truth-telling and consumer advocacy is a violation of some rule over there.
> 
> 
> Jeff



It would be my pleasure.


John


----------



## studlygoorite




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20359696
> 
> 
> I linked to a single post, and apparently the poster just deleted it. Fortunately, Pepar chimed in and quoted the post in full, so it's still visible:
> 
> http://www.gearslutz.com/board/bass-...-business.html
> 
> 
> --Ethan



This works, thanks. They have always returned my e-mails.....except for the last one where I stated " I could have trained a couple of monkeys to weave the bags by now. "


----------



## ox1216




> Quote:
> Originally Posted by *pepar* /forum/post/20352154
> 
> 
> You could put 2" - 4" of the Linacoustic on the back wall as a first reflection absorber, but you should size is only big enough to cover the first reflections from each of the front speakers to each of the ears in the main listening area. You could do the mirror thing or if you play billiards, simply visualize the lines and angles.
> 
> 
> Jeff



Thanks Jeff.


----------



## audio1246

I am thinking about adding acoustic treatments to my living room which currently functions as my HT. I went ahead and ordered some mineral wool boards (minwool 1280), and was wondering if anyone could provide suggestions about placement? The boards are 2'x4'x2".


Here is my layout. The patterned box on the right depicts vertical blinds. The floor is carpeted, and ceiling height is 8'.


The grey boxes on the left depict the wall.


----------



## scubasteve2365

I would like to get some assistance in treating my room.


My room is about 15' wide by 17' deep and 8' tall. There is a soffit in the back of the room (HVAC) that drops the ceiling height 10" (IIRC).


The room is small, and almost square.











The sketchup models should give a good representation of the room:











As of now I don't have any measurements. I've done a fair amount of reading but not enough to really get me kick-started with a solid plan because of a few confusions.


I know the common approach is bass traps, plus absorption at first reflection on side walls. I haven't done the mirror test yet but I'm an engineer, good at geometry and visualizing things, and I can't see any first reflections on the side walls for my prime seat location (the two center seats of the front row). I want to start treating this location first, as it's where I seat and I'm the only person in the house that really cares. Also, is first reflection only concerned for the LCR, do we care about surround first reflections.


Now, there is probably plenty of reflection off of the back of the room, but it appears that consensus is not to absorb back there. It really appears that the back doors is where my first reflection for the mains will meet. The Sketchup model shows glass-french doors but it's not really a french door, it's standard interior doors. I could get by with putting 4" or 6" panels (traps) on the two doors no problem. I just need to know if those panels should be absorbing anything other than LFE.


Also, would it be of any benefit to put corner traps in the corners where the full height ceiling meets the soffit? I can't put any in the corners under the soffit?


----------



## localhost127




> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20365699
> 
> 
> The room is small, and almost square.



that will make the LF range even more difficult to treat (overlapping room modes due to repeating dimensions).




> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20365699
> 
> 
> I haven't done the mirror test yet but I'm an engineer, good at geometry and visualizing things, and *I can't see any first reflections on the side walls for my prime seat location* (the two center seats of the front row).




http://imgur.com/GuC3Q.jpg%5B/IMG%5D



















here is an example:


http://imgur.com/IBNqs.jpg%5B/IMG%5D




> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20365699
> 
> 
> I want to start treating this location first, as it's where I seat and I'm the only person in the house that really cares. Also, is first reflection only concerned for the LCR, do we care about surround first reflections.



you care about any specular reflections that arrive within 20ms of the original source. an *ETC* graph will detail you these early reflections up until the last bits of energy in the room. you only need to absorb the specific reflection points (the size depends on how large your listening area/sweet spot is) - not the entire wall(s). you will want to do the mirror trick and find the first reflection points for *all speakers within the room.* (except for the subwoofer).



> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20365699
> 
> 
> Now, there is probably plenty of reflection off of the back of the room, but it appears that consensus is not to absorb back there. It really appears that the back doors is where my first reflection for the mains will meet. The Sketchup model shows glass-french doors but it's not really a french door, it's standard interior doors. I could get by with putting 4" or 6" panels (traps) on the two doors no problem. I just need to know if those panels should be absorbing anything other than LFE.



normally, thick trapping on the rear wall for LF issues --- but someone else may be able to chime in here, but i am fairly certain that most LF wave content will pass through glass (not reflect off and back into the room). measurements would be the only way to know for sure.


broadband absorption would likely be beneficial, as the rear wall is still a reflection point for mid and high freq content, and eliminating the reflection off the real wall from the front spaekers will likely allow you to hear the rear surround direct signal more clearly. you could build broadband panels on gobo stands, that you could move into place when watching a movie.



> Quote:
> Also, would it be of any benefit to put corner traps in the corners where the full height ceiling meets the soffit? I can't put any in the corners under the soffit?



with a square room, you are going to want as much bass trapping as you can manage. this includes all 12 corners within your room. there are multiple approaches here to building bass traps, but measurements would be needed first.


----------



## fotto




> Quote:
> Originally Posted by *localhost127* /forum/post/20365760
> 
> 
> 
> here is an example:
> 
> 
> http://imgur.com/IBNqs.jpg%5B/IMG%5D
> 
> 
> there are multiple approaches here to building bass traps, but measurements would be needed first.



OMG....you are so screwed Steve







(JK)


From what I've read regarding bass traps, the resounding theme has been "the more the merrier". Why are measurements needed for bass traps? Just curious.


----------



## localhost127




> Quote:
> Originally Posted by *fotto* /forum/post/20366295
> 
> 
> Why are measurements needed for bass traps? Just curious.



you need to know the initial issues inherent within the room before you can select the best type of 'treatment' to tame said issues.


you'll also want an original baseline (no pun intended) so you can test and measure the differences as you go on.


and probably the most crucial advantage of measuring --- you can compare freq responses of the room by moving speakers/sub in different positions until you find the layout with the best LF response (the best 'starting point'). from there you can apply treatments to solve specific (measured) issues.


----------



## audio1246




> Quote:
> Originally Posted by *audio1246* /forum/post/0
> 
> 
> I am thinking about adding acoustic treatments to my living room which currently functions as my HT. I went ahead and ordered some mineral wool boards (minwool 1280), and was wondering if anyone could provide suggestions about placement? The boards are 2'x4'x2".
> 
> 
> Here is my layout. The patterned box on the right depicts vertical blinds. The floor is carpeted, and ceiling height is 8'.
> 
> 
> The grey boxes on the left depict the wall.



Any suggestions anyone?


Thanks!


----------



## jamin

Here is a starting point.


----------



## audio1246




> Quote:
> Originally Posted by *jamin* /forum/post/0
> 
> 
> Here is a starting point.



Thank You!


How about a couple behind the front speakers?


----------



## localhost127




> Quote:
> Originally Posted by *audio1246* /forum/post/20365124
> 
> 
> I am thinking about adding acoustic treatments to my living room which currently functions as my HT. I went ahead and ordered some mineral wool boards (minwool 1280), and was wondering if anyone could provide suggestions about placement? The boards are 2'x4'x2".



-stack 2 panels together to make 4" deep panels.

-if you can afford the real estate, add a 2" air gap for your frame (so the actual absorption is spaced 2" from the wall when the panel is hung)

-use a mirror (against a boundary) to find all 'reflection points' --- where you can see a speaker in the mirror from the listening position. put your panels there. make sure you move around your listening area and make sure the panels are big enough to cover the reflection point if you have a large sweet-spot to account for.

-see if you can pull your couch forward a bit so you're not sitting right up against the rear wall

-install 4" panels (pref with 4" airgap) directly behind the listening position on the rear wall


that should be a good start.

do you have a mic by chance? if so, download Room EQ Wizard and reply back


broadband absorption at the early reflection points is only to address specular energy issues - not any LF issues. LF issues generally require thick porous absorption in any and all possible corners.


----------



## audio1246




> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> 
> -stack 2 panels together to make 4" deep panels.
> 
> -if you can afford the real estate, add a 2" air gap for your frame (so the actual absorption is spaced 2" from the wall when the panel is hung)
> 
> -use a mirror (against a boundary) to find all 'reflection points' --- where you can see a speaker in the mirror from the listening position. put your panels there. make sure you move around your listening area (if it's larger than one seat) and make sure the panels are big enough to cover the reflection point if you have a large sweet-spot to account for.
> 
> 
> broadband absorption at the early reflection points is only to address specular energy issues - not any LF issues. LF issues generally require thick porous absorption in any and all possible corners.



Thanks for the suggestions.


All floor corners except one are occupied with some stuff. I'm not sure how to strike a balance for the bass traps without making the room full of acoustic treatments in the corners.


----------



## localhost127




> Quote:
> Originally Posted by *audio1246* /forum/post/20366596
> 
> 
> Thanks for the suggestions.
> 
> 
> All floor corners except one are occupied with some stuff. I'm not sure how to strike a balance for the bass traps without making the room full of acoustic treatments in the corners.



if you are unable to install corner traps due to real estate constraints, then it would still be beneficial to get a mic, room eq wizard, and play with speaker/sub placement (and listening position placement) to find the best possible LF response. even moving the sub or your listening position slightly in one axis could have beneficial results.


----------



## pepar




> Quote:
> Originally Posted by *audio1246* /forum/post/20366596
> 
> 
> Thanks for the suggestions.
> 
> 
> All floor corners except one are occupied with some stuff. I'm not sure how to strike a balance for the bass traps without making the room full of acoustic treatments in the corners.



Just jumping in here .. might have missed it .. but have you looked at the wall/ceiling corners?


Jeff


----------



## audio1246




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Just jumping in here .. might have missed it .. but have you looked at the wall/ceiling corners?
> 
> 
> Jeff



Jeff,


I haven't considered ceiling corners yet, but, looks like I should now.


Thanks


----------



## pepar

Quote:

Originally Posted by *audio1246* 
Jeff,


I haven't considered ceiling corners yet, but, looks like I should now.


Thanks
With the right design, they can blend nicely.


Jeff


----------



## scubasteve2365




> Quote:
> Originally Posted by *localhost127* /forum/post/20365760
> 
> 
> 
> 
> http://imgur.com/GuC3Q.jpg%5B/IMG%5D
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> here is an example:
> 
> 
> http://imgur.com/IBNqs.jpg%5B/IMG%5D



I knew speakers had dispersion patterns and that they weren't laser beams of sound, I just didn't realize that such extreme angles of dispersion were considered.



> Quote:
> Originally Posted by *localhost127* /forum/post/20365760
> 
> 
> broadband absorption would likely be beneficial, as the rear wall is still a reflection point for mid and high freq content, and eliminating the reflection off the real wall from the front spaekers will likely allow you to hear the rear surround direct signal more clearly. you could build broadband panels on gobo stands, that you could move into place when watching a movie.



That's some of my confusion. There are first reflections back there, but based on what I've read thus far I'm uncertain if I should be doing absorption. Many posts have said not to absorb, but rather diffuse, in the rear, but then other posts, like yours, suggest to absorb.


Which leads me to another question. Let's assume I'm going to absorb back there on the rear wall at the first reflection points but all thicken up the panels for some bass trapping. I'll be applying this 2'x4' panels on the two back entry doors to the room. (Which aren't glass despite the sketchup model showing that). Would a 4" panel spaced 4" off the wall be better than a 6" panel spaced 2" off of the wall? 8" off of the door might be pushing it and I don't really want to go any deeper. Is it possible that I'd be better served just putting 2" absorption on the doors and focusing the fiberglass elsewhere for bass trapping?


When you say measurements are needed, are you just referring to the REW application?


I have a laptop, can DL the software, and I have somewhat decent dynamic microphones. Is this enough. I do not have a high quality condenser microphone.


----------



## localhost127




> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20372396
> 
> 
> I knew speakers had dispersion patterns and that they weren't laser beams of sound, I just didn't realize that such extreme angles of dispersion were considered.



the incident energy is there and can be measured with an ETC.

again, regarding specular reflections, we're not concerned with frequency - only energy. they do not function like 'lasers' across the entire range, but for sake of determining reflection points, all you need to note is that: angle of incident = angle of reflection. there is more off-axis energy present than you might assume.





> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20372396
> 
> 
> That's some of my confusion. There are first reflections back there, but based on what I've read thus far I'm uncertain if I should be doing absorption. Many posts have said not to absorb, but rather diffuse, in the rear, but then other posts, like yours, suggest to absorb.



depends on the distance to listening position and a host of other things.

absorption is a safe bet, regardless..and you can then add diffusion on top of that as long as the diffused returns dont impede the ISD.


you will still want thick LF trapping on the rear wall as the distance between your listening position and the rear wall will determine what frequency you will be in nulls at (off the rear wall)...like SBIR off the front wall, a frequency who has a 1/4wavelength distance as the same distance between your ears and the rear wall, will reflection and travel a total of 1/2wavelength (sound goes past your ears, hits rear wall, reflects back towards your ears) and combines with the original sound 180* out of phase.



> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20372396
> 
> 
> Which leads me to another question. Let's assume I'm going to absorb back there on the rear wall at the first reflection points but all thicken up the panels for some bass trapping. I'll be applying this 2'x4' panels on the two back entry doors to the room. (Which aren't glass despite the sketchup model showing that). Would a 4" panel spaced 4" off the wall be better than a 6" panel spaced 2" off of the wall? 8" off of the door might be pushing it and I don't really want to go any deeper. Is it possible that I'd be better served just putting 2" absorption on the doors and focusing the fiberglass elsewhere for bass trapping?



what material are you looking to use? the density and gas-flow resistivity of the material will determine your 'thickness' constraints.

e.g. if you're using OC703, keep layering up the panels (8" thick) and they will start to reflect. as you increase the depth of the bass traps, you want to use a material with lower gas-flow resistivity. however, for the rear wall, i'd suggest 4" with 4" air gap. if and when you measure, if you determine you have a bad null that is confirmed happening via the rear wall, then you could move the listening position slightly (towards/away from the rear wall) and/or try 6" with 2" air gap. one can't say without measurements...





> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20372396
> 
> 
> When you say measurements are needed, are you just referring to the REW application?



absolutely.

you can't treat anything until you know what your specific, measured problems are. by measuring, you can play with the listening position and/or speaker position to try and find a decent 'starting point' freq response. you're always going to have LF issues in an untreated, small acoustical space.


you will want to use broadband absorption to combat specular reflections @ the first reflection points, and then all bass trapping will take place in the corners.


you can save the expensive OC703 to be used for the broadband panels. for bass traps -- the thicker the better. the cheapest and most effective will be to use regular cheap attic insulation (pink fluffy stuff, unfaced), and make very deep corner traps filled loosely with pink fluffy stuff. as you make deeper and deeper traps, you will want to use a material with lower gas flow resistivity. the thicker the better, and the more sq area covered in the corners the better.



> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20372396
> 
> 
> I have a laptop, can DL the software, and I have somewhat decent dynamic microphones. Is this enough. I do not have a high quality condenser microphone.



i have a few bookmarks ill post when i return to my home pc.


----------



## ox1216

I'm making my acustic pannels and was wondering do I need acustic transparant material (ie GOM) to cover them, or is getting fabric from Jo Ann fabrics etc. ok?


-Alan


----------



## nathan_h




> Quote:
> Originally Posted by *ox1216* /forum/post/20378242
> 
> 
> I'm making my acustic pannels and was wondering do I need acustic transparant material (ie GOM) to cover them, or is getting fabric from Jo Ann fabrics etc. ok?
> 
> 
> -Alan



Use the "blow test". If you can put it up to your mouth and blow air through it and feel it on the other side relatively unimpeded, then it is porous enough to work over a panel.


----------



## nezff

 Attachment 210631


----------



## audio1246




> Quote:
> Originally Posted by *nezff* /forum/post/0



How did the treatments improve the sound quality? Any remarkable improvements?


----------



## Jailguy

I had posted this in it's own thread, but it was suggested that I may get more help here.

I've seen a lot of articles in the past about attempting to use risers as a broadband bass trap. My situation is a little bit different. Due to a low ceiling and my wife not wanting one, I scrapped my plans for a riser. (for now )


Anyways, I'll be building my stage in the next few days and was wondering if my idea would make any difference. My stage is not nearly as big as a riser and I know size plays a big part in bass trapping. My stage will be 11ft wide x 22" deep x 5.5" tall. I am not filling it with sand because my speakers and subs will be sitting on the concrete floor behind the stage. I will have about 30" of space between the back of the stage/false wall and my front wall. I was thinking about drilling about 10 or so 4" holes in the back side of the stage and filling the stage with insulation. Should I even bother with the holes? Will it act as a bass trip at all? Does it need vents in the opposite end?


FYI, I will also have "super chunk" style bass traps in the front corners and along the front ceiling.


Thanks!


----------



## nezff




> Quote:
> Originally Posted by *audio1246* /forum/post/20379977
> 
> 
> How did the treatments improve the sound quality? Any remarkable improvements?



cut down on the whole echo problem.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/20361626
> 
> 
> Would appreciate an update when available. I got jumped all over with emails to my _private_ email addresses by the CEO of this company. He made wild accusations about me and my "goal." I told him I had no goal and only had given sound advice to someone who had waited six months with no product to show after having paid in full. Now the mod has deleted my post and has closed the thread. Apparently truth-telling and consumer advocacy is a violation of some rule over there.
> 
> 
> Jeff



That is a shame, on both points.


----------



## petetwinofpat

my room dimensions are 14w 8.5 high 26 deep........rear seats are on a 8ft platform 10in high..front row is 14 ft away from screen. screen is 3 ft off front wall (stewart luxus a retracting sscreen) w is acoustically transparent....front 3 speakers are directly behind the screen. 2 subs up front 4 speakers in ceiling acrooss from each row and 2 speakers on back wall....chairs also have shakers in them....just looking for the best treapments for the room..thanks in advance.....pete


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/20383788
> 
> 
> That is a shame, on both points.



If I were a regular there, I would have pressed the issue.


Jeff


----------



## Ethan Winer




> Quote:
> Originally Posted by *petetwinofpat* /forum/post/20402012
> 
> 
> just looking for the best treatments for the room.



Best? With room treatment you can have effective, attractive, or affordable. Pick any two.










--Ethan


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *scubasteve2365* /forum/post/20365699
> 
> 
> I would like to get some assistance in treating my room.
> 
> 
> I know the common approach is bass traps, plus absorption at first reflection on side walls. I haven't done the mirror test yet but I'm an engineer, good at geometry and visualizing things, and I can't see any first reflections on the side walls for my prime seat location (the two center seats of the front row). I want to start treating this location first, as it's where I seat and I'm the only person in the house that really cares. Also, is first reflection only concerned for the LCR, do we care about surround first reflections.
> 
> Hi Steve,
> 
> 
> Well, first, I gotta stop you there. It has been repeated over and over in this thread alone...and I guess we'll beat that horse again...but absorbing the "first" reflections is not a good idea. High frequency information is very desirable at this location, so by boradband absorbing it...we effectively kill it. The result is a narrower view of your acoustical sound stage. That being said, absorption at targeted frequencies IS desirable without destroying the high freqs.
> 
> 
> Now, there is probably plenty of reflection off of the back of the room, but it appears that consensus is not to absorb back there.
> 
> Not quite right again. We want a cobination of treatment back there. It just depends on what reflection is occurring where, what the function of that source of sound is, and where we are sitting. It is never clear cut. Keep in mind, there are rules of thumb, but what we are trying to do is shape the sound. So, there is a significant artistic element at play here, which us right brainers often have trouble with. I have yet to have two identical acoustical treatment layouts for any of the theater layouts I have done. I just know what type of sound I want to create (clients later typcially agree wholeheartedly), so I can now lay that treatment plan out in a CAD format without the need for hearing it. However, that comes with experience and playing around in the past...two costly options. The point now is to save someone money by getting it right the first time around.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hope this helps a little.


----------



## pepar

scubasteve2365 - http://www.avsforum.com/avs-vb/showt...3#post17390783 


If you follow this Member's advice you will likely have achieved 80%-90% of all that can be done. BasementBob is knowledgeable and experienced. He is the person responsible for the webpage chocked full of absorption coefficients. Furthermore, he is not selling anything.


If you want to push your theater to the pinnacle and have a high net worth, the pros here can do it. If you are a DIYer and want to educate yourself enough to have a great sounding theater, then stay focused and do more research. Searching out BasementBob's posts are a good place to start.


And by the way, you might want to kill the lateral first reflections if your speakers have bad off axis response. But even the experts don't agree beyond that.


My $.02.


Jeff


----------



## Ethan Winer




> Quote:
> Originally Posted by *pepar* /forum/post/20407825
> 
> 
> BasementBob is knowledgeable and experienced. He is the person responsible for the webpage chocked full of absorption coefficients. Furthermore, he is not selling anything.



I can't resist pointing out that sometimes the people who selling products are the most knowledgeable _because_ they're in the business, and they've made a commitment to becoming experts.


--Ethan


----------



## pepar

I re-worded my post a few times before actually posting, but still might have had the wrong slant. Your company and the others here as well as the pure acousticians/consultants are all professional and provide products and services that are worth the prices.


But I must admit that the cynic in me has to chuckle when I read a post intended to plant doubt about conventional wisdom that serves most people well in most situations, and does it in a way that suggests that the poster is uniquely qualified to navigate the member to which they were responding through the complex variables involved.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/20408600
> 
> 
> But I must admit that the cynic in me has to chuckle when I read a post intended to plant doubt about conventional wisdom that serves most people well in most situations, and does it in a way that suggests that the poster is uniquely qualified to navigate the member to which they were responding through the complex variables involved.
> 
> 
> Jeff



Hmmmm...IMHO I feel the question should be, are they uniquely qualified? Be that aside, what "conventional wisdom" are you referring to? I find that an interesting comment.


----------



## nathan_h




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20409133
> 
> 
> Hmmmm...IMHO I feel the question should be, are they uniquely qualified? Be that aside, what "conventional wisdom" are you referring to? I find that an interesting comment.



I'm gonna guess pepar is referring to broadband absorption at the first reflection points on the side walls, a never ending topic of controversy. Even the chief proponent of doing away with such absorption admits that in controlled listening tests, while unskilled listeners prefer listening without such treatments, professional listeners (eg, audio engineers) are split 50/50 on the subject when it comes to preference. In terms of recreating the environment in which the audio was mixed, every dubbing stage I have seen or been to (eg, Warner Bros.) has such broadband absorption. It is was what the mixer, engineer, and sound designer had when they created the soundtrack and what they expect/design for, when the soundtrack is reproduced in a reference environment.


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20409133
> 
> 
> Hmmmm...IMHO I feel the question should be, are they uniquely qualified? Be that aside, what "conventional wisdom" are you referring to? I find that an interesting comment.



Generally, right-sized absorbers at the first reflection points and bass traps work well in most residential spaces. That is the conventional wisdom to which I was referring. It was your un-categorical debunking of that .. "absorbing the "first" reflections is not a good idea" .. that caught my attention. Might diffusion be appropriate at the front left and right points? Maybe, but so might absorption. And here is recent post from Dennis Erskine saying just that.


And then we have nathan_h's spot on post that cites good reasons why your definitive "absorbing the "first" reflections is not a good idea" statement may not be true.


Jeff


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/20409675
> 
> 
> Generally, right-sized absorbers at the first reflection points and bass traps work well in most residential spaces. That is the conventional wisdom to which I was referring. It was your un-categorical debunking of that .. "absorbing the "first" reflections is not a good idea" .. that caught my attention. Might diffusion be appropriate at the front left and right points? Maybe, but so might absorption. And here is recent post from Dennis Erskine saying just that.
> 
> 
> And then we have nathan_h's spot on post that cites good reasons why your definitive "absorbing the "first" reflections is not a good idea" statement may not be true.
> 
> 
> Jeff



Hi Jeff,


I'll take a shot in the dark, and hopefully clarify what I am referring to. What I believe Dennis is saying in the above mentioned link, is that IF a speaker has a bad off-axis response, then it is best to absorb the entire frequecy range (at least that which broadband absorption can absorb). However, with most speakers, at least the ones I have tested, the off-axis response is usually pretty good. So, given that, I personally am not interested in throwing away any information which can be quite useful in creating the sound envelopment I am often looking for. Part of that recreation lies within the higher frequencies and their respective reflections. However, there are some reflected frequencies I am NOT interested in keeping around either which depend on a few things. There are several ways of achieving this, and some ways are better than others, but there are low cost DIY alternatives (which I have used in the past) that get you most of the way there, and some professionally made products that work a little better in many respects. The point I am trying to make is getting someone to think a little bit without resorting to using cookie cutters. Understanding was always a much better place to be IMHO.


----------



## localhost127




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20410727
> 
> 
> Hi Jeff,
> 
> 
> I'll take a shot in the dark, and hopefully clarify what I am referring to. What I believe Dennis is saying in the above mentioned link, is that IF a speaker has a bad off-axis response, then it is best to absorb the entire frequecy range (at least that which broadband absorption can absorb). However, with most speakers, at least the ones I have tested, the off-axis response is usually pretty good. So, given that, I personally am not interested in throwing away any information which can be quite useful in creating the sound envelopment I am often looking for. Part of that recreation lies within the higher frequencies and their respective reflections. *However, there are some reflected frequencies I am NOT interested in keeping around either which depend on a few things.* There are several ways of achieving this, and some ways are better than others, but there are low cost DIY alternatives (which I have used in the past) that get you most of the way there, and some professionally made products that work a little better in many respects. The point I am trying to make is getting someone to think a little bit without resorting to using cookie cutters. Understanding was always a much better place to be IMHO.



could you expand on the comment in bold?


i was under the impression that we shouldn't be discussing or breaking down specular reflections in terms of 'frequency' - but im interested to hear any commentary discussing otherwise. thanks!

http://www.gearslutz.com/board/6424136-post4.html


----------



## Dennis Erskine

Well...this is a long, winding road ...

I would, first, want to dismiss the "Warner Bros" comment above ... I very much doubt many on this forum have a playback space the size of WB's dubbing/sound stages.


The suggestion "early reflections are bad" is categorically wrong. It might be better stated as "not all early reflections are bad". In this general context "early" is defined only in the time domain. This, in of itself, is only 1/3rd of the story. If you want to use (and reference) the work of Haas, you also need to note his work discussed not only the delta between the direct and reflected sound, he also referenced the relative loudness differences between the direct/reflected sound.


There is a time interval, the "fusion zone" where we are not aware of the reflected nature of the sound ... ie, those reflections are not heard or perceived as separate events. Within this fusion zone all of the reflected sounds are audible, fused with the direct sound, and contribute to timbre and loudness.


So, let's step back from all of this and bring in this diffusion and off axis response stuff. First, if the off axis response is significantly different than the on axis response, you don't want those reflections contributing to the timbre of the sound received at your ears. (A strong argument for constant directivity speakers.) This is a case supporting absorption. Second, since we're not wanting to toss good frequency response away, should that response fall into the echo zone or into the "perceived as another 'source' zone, we need to do something about that. Remembering that there are *two* criteria, one being a delta in time and the other being loudness, we can affect both the loudness and time with diffusion without the corresponding risk where absorption can kill the width and depth of the sound stage.


Going back to Haas and related work, we must note that early reflections can cause a slight image shift resulting in a perceived increase in the size of the source. This is not necessarily a bad thing. Associated with IACC, this brings "spaciousness". Careful management of the delays and levels of early reflected sounds can widen the source creating a sound stage wider than your room.


A couple of other comments -

First, absolutely any comparison of sound stages, dubbing stages, mix rooms, commercial theaters and auditoria to small rooms is, frankly, wrong and way off base. Large rooms and small rooms are radically different. Second, when considering your broadband absorption needs, to do so correctly, you must account for the TL of the walls and the absorption coefficients of the boundaries themselves. Just throwing fuzzy stuff on the walls can make things better or make things worse.


----------



## localhost127

nice post, Dennis.


i would only like to add that the term 'diffusion' is often used as being far far too vague. with absorption, it's fairly straight-forward: absorption that is effective throughout the entire freq range of specular energy, and confirmed with ETC (although we still see people using thin absorption which is only effective in absorbing the HF content).


with diffusion, there are many options (and design criteria) for diffusers and/or scattering devices. i see people blindly recommending 'diffusers' at areas of early reflection points, but rarely see any further commentary on the type of diffusion (spatial + temporal diffusion? or only spatial? etc), design freq, cut-off frequencies, how many periods in the array, etc? in a rectangular room, the diffuser (like a broadband absorption panel), would not have incident sound at 0* unless mounted on an angle. thus, this would decrease the HF cutoff of the diffuser. most PRDs/QRDs perform much better lobing with multiple periods (and using Barker Code)... so if one wishes to place diffusion at an area of early reflection, what design criteria of the diffuser would one recommend??


----------



## Dennis Erskine

Depends on the room, distances, speaker, etc.


..or you can adopt the universal answer which is 42.


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20411293
> 
> 
> Just throwing fuzzy stuff on the walls can make things better or make things worse.













The point I was trying to make, but may have obscured, is that with audio, like video, there is a reference standard in the movie industry for how the room sounds and behaves -- how it measures.


The best way to achieve this standard is professional design and construction. Some people, like the OP, want a solution that gets them part of the way there, without hiring a professional, measuring their room, or spending much money.

*So we are now in the realm of not measuring gray scale, but adjusting hue and "color" until skin tones look "right".*


It may not be possible to improve most domestic spaces with any "rules of thumb". I agree that one cannot categorically state that side wall absorption or bare walls or some other solution works in every case.


My point is that in my experience, broadband side reflection absorption helps in more cases than it hurts, so after bass trapping (which is #1 on my "rules of thumb" short list), if one doesn't want to measure and construct to the audio standard, broadband side reflection absorption is my next default action to recommend.


----------



## FOH

And....


If one does proceed with addressing early, adjacent surface reflections, _then do it properly._




To me, there seems to be so much consternation (rightfully so) wrt which avenue to take. Then, upon determining diffusion there, absorption here,..etc.., and ultimately putting up an absorption panel(s), prudence isn't oftentimes being used in precise location, thickness, spacing, orientation, angle of incidence, gas flow resistivity variance and inconsistencies depending on which side actually "sees" the energy,..etc. Individuals just put 'em up. "C+ is good enough". Perhaps aesthetic concerns trump the pursuit of the goal,..I don't know. I'm not diminishing the importance of aesthetics either. The mind operates in fantastic ways regarding visual appeal. However, with a little effort, one can have it all.


So much discussion and energy is put forth, then the actual implementation is poorly executed. If you're going to attenuate problematic early reflections with some material, then do it properly for goodness sake. Some time ago, I discovered merely moving the treatment panel away from the speaker slightly, so that the perpendicular side, _side_, is exposed to the direct energy, a overwhelmingly more effective attenuation occurs. Otherwise, glancing or grazing angles of incidence are merely mediocre wrt absorption efforts.


Additionally; In my opinion, a very precise, modest, and still effective methodology in this regard, can retain _spaciousness_, and yet allow the recorded material possess the _clarity and image specificity_ that the engineering team wanted consumers to experience.



Thanks


----------



## pepar

Quote:

Originally Posted by *FOH* 
"C+ is good enough".
Untreated spaces are usually F, so C+ is an incredible upgrade. Sort of like "In the land of the blind, the one-eyed man is king."


Jeff


----------



## localhost127

Quote:

Originally Posted by *pepar* 
Untreated spaces are usually F, so C+ is an incredible upgrade. Sort of like "In the land of the blind, the one-eyed man is king."


Jeff
understood and certainly fair enough.


i think FOH's point is, we shouldn't be succumbing to the lowest common denominator, but instead presenting the most appropriate ways to selecting and applying treatment (consistent with measurements), in which others can _then_ determine their own level of involvement. if one does not take the time and effort to take measurements in their room, which would then be used to select treatments, which would then be installed and post-measurements taken to verify the original problem has indeed been solved, then one shouldn't expect much more specific help from within the community.


just because "most" living rooms cannot aesthetically handle most of the treatments made to address fundamental issues in small acoustical spaces, doesn't mean we shouldn't continue to put the prime focus on the proper way to do things. this is, after all, the _Acoustical Treatments Master Thread_ in the *Dedicated Theater Design & Construction* subforum.


----------



## pepar

Quote:

Originally Posted by *localhost127* 
understood and certainly fair enough.


i think FOH's point is, we shouldn't be succumbing to the lowest common denominator, but instead presenting the most appropriate ways to selecting and applying treatment (consistent with measurements), in which others can _then_ determine their own level of involvement. if one does not take the time and effort to take measurements in their room, which would then be used to select treatments, which would then be installed and post-measurements taken to verify the original problem has indeed been solved, then one shouldn't expect much more specific help from within the community.


just because "most" living rooms cannot aesthetically handle most of the treatments made to address fundamental issues in small acoustical spaces, doesn't mean we shouldn't continue to put the prime focus on the proper way to do things. this is, after all, the _Acoustical Treatments Master Thread_ in the *Dedicated Theater Design & Construction* subforum.
So, how do we strike a balance between cluing people in that there are levels of effectiveness that do involve testing and depth of experience without dumping on simple, rules of thumb that work in many instances? Without discouraging them from doing simple things and still letting them know that there is more if they care to learn about it?


How do we set them up so that they can understand the RealTraps and the GIKs and what they can do for them, and then put the Erskines into perspective and what _they_ can do, all while still encouraging personal research and perhaps a DIY approach?


----------



## Dennis Erskine

I think a knowledgeable consumer is a great client. By the same token this has to be put into perspective. One can study, listen to opinions, and get hung up in Absorption Coefficient tables, and believe they have their arms around the topic. It is my opinion that many, after their "research" efforts, believe they've got it when, in fact, they've only scratched the surface. What I appreciate about the HAA Level 1 class ( www.homeacoustics.net ) is after two days, people leave with a valuable, practical knowledge base AND understand there's just a whole bunch more under the covers. It's rather like researching a medical condition ... you really need to do your research; but, after you have, you also need to understand that doesn't qualify you as an surgeon.


OTOH, re-education is problematic when someone has been spoon fed misinformation, myths and wild guesses from those they believe know their stuff have a real disadvantage over those who start off getting the correct information. "Always absorb early reflections ... well it worked for me" is a way to start off on the wrong foot. It may sound better but so many have been listening to such horribly bad stuff for so long, even a minor improvement is amazing. Just imagine what it would be if they spent the same money doing it "right" (whatever that is) rather than simply going after a "rule of thumb".


----------



## localhost127

so, if someone enters into this thread looking for help - i assume the first request is still 'measurements of the room pre-treatment', correct? i think everyone can agree on that?


----------



## fotto




> Quote:
> Originally Posted by *localhost127* /forum/post/20415726
> 
> 
> so, if someone enters into this thread looking for help - i assume the first request is still 'measurements of the room pre-treatment', correct? i think everyone can agree on that?



JMHO, but I really don't see how that's going to work. You have people popping in here before, during, and after their builds. I'd venture a guess that less than 5% of folks here doing a build even have the equipment to do any measurements. Although it's not a big investment (maybe


----------



## nathan_h




> Quote:
> Originally Posted by *fotto* /forum/post/20415839
> 
> 
> JMHO, but I really don't see how that's going to work. You have people popping in here before, during, and after their builds. I'd venture a guess that less than 5% of folks here doing a build even have the equipment to do any measurements. Although it's not a big investment (maybe


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/20415960
> 
> 
> Actually, often the experts respond to graphs with useful, detailed feedback. If you have measurements, go ahead and post them.
> 
> 
> That said, I ended up going with a pro, too, for the reasons Dennis cites: I knew enough to be dangerous, but not enough to be confident, and the investment in a professional set of measurements and advice was a good investment in peace of mind.



Were you able to look at the measurements and understand why the advice was what it was?


Jeff


----------



## nathan_h

I approached it as I do most professionals: Asked a lot of questions and had him explain the meaning and recommendations in as plain of English as possible.


----------



## pepar




> Quote:
> Originally Posted by *fotto* /forum/post/20415839
> 
> 
> JMHO, but I really don't see how that's going to work. You have people popping in here before, during, and after their builds. I'd venture a guess that less than 5% of folks here doing a build even have the equipment to do any measurements. Although it's not a big investment (maybe


----------



## fotto

Nathan & Jeff, I don't disagree with your comments at all. My main point was that I don't believe that limiting this thread to those who have measurements in hand for advice will work.


Citing Dennis as an example, his input here is valuable and he's a great resource, but I would not expect him to go full disclosure on a room treatment plan in response to a post of measurements.


----------



## pepar

Agree on all counts, Floyd.


----------



## nathan_h




> Quote:
> Originally Posted by *fotto* /forum/post/20416077
> 
> 
> Nathan & Jeff, I don't disagree with your comments at all. My main point was that I don't believe that limiting this thread to those who have measurements in hand for advice will work.
> 
> 
> Citing Dennis as an example, his input here is valuable and he's a great resource, but I would not expect him to go full disclosure on a room treatment plan in response to a post of measurements.



Oh, I agree that we should not try to limit this thread to people who can measure or interpret measurements.


But at some point, all the answers enter the realm of "it depends" and then the answer is "it depends on how the room measures, and that will dictate what options one should consider".


I still point people to Ethan's article: http://www.realtraps.com/art_room-setup.htm since following his advice will usually improve most systems, imo.


But to Dennis' point, there is no one size fits all solution. If there was, this thread would have a single post at the start with all the best practices, and just be full of questions about how to achieve them.


But if we posted the standards in the first post, I think people who just give up. That is, we'd be telling people the technical goal, but not how to achieve that goal. And if we were comprehensive in how to achieve that goal, well, this would be a long course in acoustics!


For example, if one wanted to design to a standard, there is this one:

http://www.aes.org/technical/documents/AESTD1001.pdf 


Or this for TV, which explains a lot about why some TV shows are funky:

http://www.atsc.org/cms/standards/a_85-2009.pdf 


Or what Dolby recommends, including these cool summaries:


Room dimensions:











And reverberation time:











----------


But none of these tell people what acoustical treatments to use to achieve those results -- because that is something that is not cookie cutter.


But I'll say again, I do think there are some common problems in domestic rooms that can likely be partially improved with room layout changes and simple acoustic treatments. Yes, measurements and custom design will achieve better results, perhaps by contradicting the some rules of thumb. But improvement can often be seen by following some cookie cutter basics (if for no other reason that most rooms start out so poor). I mean, are there many rooms that won't benefit from broadband bass trapping?


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/20416255
> 
> 
> 
> But I'll say again, I do think there are some common problems in domestic rooms that can likely be partially improved with room layout changes and simple acoustic treatments. Yes, measurements and custom design will achieve better results, perhaps by contradicting the some rules of thumb. But improvement can often be seen by following some cookie cutter basics (if for no other reason that most rooms start out so poor). *I mean, are there many rooms that won't benefit from broadband bass trapping?*



Good point. Maybe that is the only rule of thumb that makes the cut?


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/20416255
> 
> 
> 
> I still point people to Ethan's article: http://www.realtraps.com/art_room-setup.htm since following his advice will usually improve most systems, imo.



That is where I was a few pages ago. Ethan recommends treating all first reflection points, something I thought was a standard rule of thumb. Is there any doubt why people can be easily confused?


So, is it the case where "right-sized" absorbers at all first reflection points will make some untreated room worse, or they will improve every un-treated room but diffusion _might_ be better?


Jeff


----------



## fotto




> Quote:
> Originally Posted by *pepar* /forum/post/20416364
> 
> 
> Good point. Maybe that is the only rule of thumb that makes the cut?



(+1) That's about the thing that I have found to be globally consistent to date.


----------



## Dennis Erskine

...and, to the point, in small rooms there is no such thing as RT60 (really).


----------



## Dennis Erskine




> Quote:
> I mean, are there many rooms that won't benefit from broadband bass trapping?



How much? What techniques should be used to prevent over absorption in some "broadband" range because of a loss related to wall impedance? So, one more "rule of thumb" which shouldn't be just implemented because it worked somewhere else.


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20417143
> 
> 
> How much? What techniques should be used to prevent over absorption in some "broadband" range because of a loss related to wall impedance? So, one more "rule of thumb" which shouldn't be just implemented because it worked somewhere else.



Evidently, we have no more thumbs.


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Evidently, we have no more thumbs.



Sort of. One appraoch is definitely "do nothing without a professional". I'm sure glad i didnt take that appraoch because even before my room was measured i followed the advice of Ethan and the folks at GIK and i am very glad i did. When later the room was measured and it came time to act on the room measurements there was very little left to do.


I guess the question for Dennis is what advice can you provide? Maybe the advice is that one really needs to take the HAA level 1 training and do thorough measurements, or do nothing.


----------



## Dennis Erskine

I do believe an educated consumer is an excellent idea. The HAA class would be an eye opener for most. The take aways should be:

1. The solution that worked for one room, may not work for another room ... each room is specific;

2. Be very careful of "rules of thumb" ... they may be good for your thumbs but could very easily do more damage than good;

3. Nathan_h did seek outside professional advice (from GIK, Ethan for example) ... like any other "rule of thumb" you don't really need to measure first (it is a good idea) but you should provide plans/layouts to your supplier. You'd be surprised at how close you can get.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20420194
> 
> 
> I do believe an educated consumer is an excellent idea. The HAA class would be an eye opener for most. The take aways should be:
> 
> 1. The solution that worked for one room, may not work for another room ... each room is specific;
> 
> 2. Be very careful of "rules of thumb" ... they may be good for your thumbs but could very easily do more damage than good;
> 
> 3. Nathan_h did seek outside professional advice (from GIK, Ethan for example) ... like any other "rule of thumb" you don't really need to measure first (it is a good idea) but you should provide plans/layouts to your supplier. You'd be surprised at how close you can get.



expanding on Dennis' comment:


1. The *visible* solution that worked for one room, may not work for another room ... each room is specific;


e.g., there's likely a lot of 'behind the scenes' stuff going on. dont mimic a room based on photos alone


----------



## price3

Is there a way to reduce the extreme variations in bass response I see in my room from one measurement to the next? I believe it has to do with mic positioning, but it seems crazy to me to EQ my sub to the response I want when I can move my head 2 feet and it's radically different.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *localhost127* /forum/post/20420469
> 
> 
> expanding on Dennis' comment:
> 
> 
> 1. The *visible* solution that worked for one room, may not work for another room ... each room is specific;
> 
> 
> e.g., there's likely a lot of 'behind the scenes' stuff going on. dont mimic a room based on photos alone



Yes!







One thing I always say is that there is nothing arbitrarily placed in a theater. Everything serves a purpose and was intentionally placed there. There are numerous "Behind the scenes stuff" occurring all at once.


----------



## FOH

Very good discussion.


It's my opinion, that we shouldn't dismiss the so called "rules of thumb" so quickly. I'm absolutely aware of the significance of a properly analyzed, designed, implemented, acoustical solution for a room. Whether that's achieved via a professional contracted to do the work, or an enthusiast with an adequate skill-set to get the results desired. But, the common rules of thumb that bass trapping and addressing first early reflections from adjacent surfaces shouldn't be so quickly dismissed.



> Quote:
> Be very careful of "rules of thumb" ... they may be good for your thumbs but could very easily do more damage than good;



I agree with Dennis in stating we must be very careful with our approach,..but not at the expense of not trying something, or proceeding with simple treatments. How much harm can be done if one addresses the first 15msec with some modest absorption? Losing a little apparent source/image size and gaining some clarity and image specificity? It's OK, that's not harmful.


Likewise, if one were so inclined to address those same early reflections with some measure of diffusion, at least the energy within the initial 15msec window becomes predominantly direct in nature. Therefore lessening the smearing and detrimental effects of reflective components within that critical period.


Yes, one should be weary of one size fits all approaches,..but not at the expense of addressing the common problems afflicting _most_ small rooms.




Thanks


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *price3* /forum/post/20420523
> 
> 
> Is there a way to reduce the extreme variations in bass response I see in my room from one measurement to the next? I believe it has to do with mic positioning, but it seems crazy to me to EQ my sub to the response I want when I can move my head 2 feet and it's radically different.



multiple subs is the only treatment I'm aware of for uneven response across the room


----------



## FOH




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20420974
> 
> 
> multiple subs is the only treatment I'm aware of for uneven response across the room



Yes, a multi-sub approach is the best avenue toward response smoothing over a wide area within the room.


There is however, one alternative for smooth response with merely a single sub. That would be near-field positioning. It's difficult to implement due to localization, however very enlightening and a fun exercise. A relatively flat response is attainable. I'm sensitive to lateral positioning, so I found directly behind, or in front of the LP worked best. Localization remained somewhat problematic. [email protected] LP sure benefits







I've since moved on.



Good luck


----------



## CruelInventions




> Quote:
> Originally Posted by *FOH* /forum/post/20421208
> 
> 
> ..........I'm sensitive to lateral positioning, so I found directly behind, or in front of the LP worked best......



I see a whole new untapped market opening up... introducing, the subwoofer ottoman!


----------



## pepar




> Quote:
> Originally Posted by *FOH* /forum/post/20420957
> 
> 
> Very good discussion.
> 
> 
> It's my opinion, that we shouldn't dismiss the so called "rules of thumb" so quickly. I'm absolutely aware of the significance of a properly analyzed, designed, implemented, acoustical solution for a room. Whether that's achieved via a professional contracted to do the work, or an enthusiast with an adequate skill-set to get the results desired. But, the common rules of thumb that bass trapping and addressing first early reflections from adjacent surfaces shouldn't be so quickly dismissed.
> 
> 
> 
> 
> I agree with Dennis in stating we must be very careful with our approach,..but not at the expense of not trying something, or proceeding with simple treatments. How much harm can be done if one addresses the first 15msec with some modest absorption? Losing a little apparent source/image size and gaining some clarity and image specificity? It's OK, that's not harmful.
> 
> 
> Likewise, if one were so inclined to address those same early reflections with some measure of diffusion, at least the energy within the initial 15msec window becomes predominantly direct in nature. Therefore lessening the smearing and detrimental effects of reflective components within that critical period.
> 
> 
> Yes, one should be weary of one size fits all approaches,..but not at the expense of addressing the common problems afflicting _most_ small rooms.
> 
> 
> Thanks



Sooo, the thumbs are back ... with reservations? It just didn't make sense that there was nothing that could be done without measurements and consultations.


I am on the HAA website .. thought I'd see when/where I could take Level I. Unfortunately, I can't get to Beijing, UK or Australia in time. How often - and where - do they hold these?


Jeff


----------



## pepar




> Quote:
> Originally Posted by *CruelInventions* /forum/post/20421310
> 
> 
> I see a whole new untapped market opening up... introducing, the subwoofer ottoman!



And ottoman traps!


----------



## pepar

For anyone interested, the HAA website has a synopsis of the Level I course that is very interesting .. and comprehensive. And beyond that is a " self test " that is also interesting!


Jeff


----------



## jamin

pepar--


Thought I saw an Orlando class in late May.


----------



## pepar

geez, what page was i on before? yes, there it is. i'll need to wait until they get closer to the northeastern/mid-atlantic area.


----------



## SierraMikeBravo

Not sure what Gerry's schedule is as a class just popped up today in early June in Sioux Falls. Earliest that I am aware of that is closest to you would likely be the CEDIA class in Indy in September. If I may be so bold, you may also want to consider the Level II class as well. That's where the rubber really meets the road! You'll get a chance to treat a room to your heart's content.


----------



## pepar

Thanks, SMB, one step at a time. First the theory and then the hand's on where theory is related to solid reality and one can "hear" the results. Indiana is a bit too far; my comfortable range is 5-6 hours of driving one way. Richmond to NYC and west to Cincinnati-ish/Cleveland-ish is doable.


I want to apologize to you for a post that was not respectful of your accomplishments. I especially like that you are grounded in atmospherics.










Jeff


----------



## SierraMikeBravo

^^^^


No worries!







Glad I can be of help when and where I can. I know that Gerry sometimes has a class in the northeast...just not sure how often. Contact them if you want to see if something is in the works. I know they had a class last November in Boston, so they do happen. I can say without hesitation that both HAA Level I and II will probably be the most intense class most people have ever taken. Well worth the time and effort! If for nothing else, the opportunity to at least meet Jamin if he comes! That entertainment is worth the price of admission right there!


----------



## jamin

SMB-

Capitalizing jamin is like calling me Sir instead of reserving the honorific for my dad!


----------



## jamin

pepar-

I know some L1 classes have been held at RPG. Dunno if that fits your geography or if one will come along near term-just saying.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *jamin* /forum/post/20424080
> 
> 
> smb-
> 
> capitalizing jamin is like calling me sir instead of reserving the honorific for my dad!



:d


----------



## pepar




> Quote:
> Originally Posted by *jamin* /forum/post/20424095
> 
> 
> pepar-
> 
> I know some L1 classes have been held at RPG. Dunno if that fits your geography or if one will come along near term-just saying.



RPG Diffusor Systems in Upper Marlboro, MD? Yes, that is about an hour away. I should email HAA and see what they have in the works.


Jeff


----------



## Elill

Hi all,


I am DIY'ing some speakers for our living room that will be "on wall" mounted. The baffle will be about 600x600 (or 2ft by 2ft).


Adding treatments to the wall is difficult (WAF issues). One idea I did have however was to cover the baffle of the speakers in 1"-2" of 701 et al - having it in line with drivers (i.e. the drivers wouldn't be recessed).


The other idea I had was to get some raw RPG BAD panel and use that instead of the insulatiuon. Cant get the Quest products here....


Toole says adding absorption to the front wall improves localisation and reduces coloration....this wont be on the wall, but on the baffle.


Any advice would be appreciated


----------



## rnrgagne

Hi Guys,


I having to move my HT to a new room I'm building from scratch and I'm wondering about soffits and their potential benefits, or lack thereof from a room acoustics perspective. Any design suggestions or things to avoid?

I'm pretty sure I won't want to treat the undersides of them, but would treat the insides...


Thanks,

Rick.


----------



## Dennis Erskine

Peter .... yes cover the baffle wall. You can use two layers of 1" 1.5 pcf fiberglass and install 3 mil plastic sheeting between the layers.


Rick ... treating the bottom of the soffits is more beneficial.


----------



## rnrgagne




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20439093
> 
> 
> Rick ... treating the bottom of the soffits is more beneficial.



Hmm, I wonder if make them open bottomed and covered with material like speaker cloth? I could do OC703 then mineral wool on top.... wouldn't they act like corner traps then? (I want to use as much of the materials I have in my current theater as possible and I have a ton of the above mentioned.)


----------



## pepar




> Quote:
> Originally Posted by *rnrgagne* /forum/post/20439661
> 
> 
> Hmm, I wonder if make them open bottomed and covered with material like speaker cloth? I could do OC703 then mineral wool on top.... wouldn't they act like corner traps then? (I want to use as much of the materials I have in my current theater as possible and I have a ton of the above mentioned.)



I think they'd need to be open-bottomed and open-sided to have a chance of performing like a corner trap. IOW, sound must strike it unrestricted/unimpeded. I have seen soffits made entirely of acoustical material; it is a way to add corner traps in a .. possibly .. more aesthetically pleasing way.


If your soffits are mechanical chases and can't be 100% 'glass, then Dennis' advice is more appropriate. He's the pro and I didn't even stay at a Holiday Inn Express last night.


Jeff


----------



## Dennis Erskine




> Quote:
> If your soffits are mechanical chases and can't be 100% 'glass, then Dennis' advice is more appropriate. He's the pro and I didn't even stay at a Holiday Inn Express last night.



If the soffit is open bottom the only difference would be the depth of the absorber, right?


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20440028
> 
> 
> If the soffit is open bottom the only difference would be the depth of the absorber, right?



Open bottom only and not on the "side" wouldn't impede it's performance?


Jeff


----------



## Elill




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20439093
> 
> 
> Peter .... yes cover the baffle wall. You can use two layers of 1" 1.5 pcf fiberglass and install 3 mil plastic sheeting between the layers.



Thanks Dennis, will do.


----------



## Dennis Erskine




> Quote:
> Open bottom only and not on the "side" wouldn't impede it's performance?



Not what I said. I said, the bottom should be treated (not the side). You suggested "treating" side and bottom (by means of a 100% 'glass soffit). You then suggested my suggestion would be only (or more) appropriate with an open bottom only. The fact of the matter is the only difference is the depth of the absorber (bottom open only) and the depth of the absorber (side and bottom open).


On the other side of that, soffits are too small to do much good in the low frequencies and leaving the whole thing open to the 100% glass fill runs the risk of over absorption of the high frequencies. OTOH, most of you with 1" dome tweeters and seating distances greater than 8 to 10 feet are suffering through HR rolloff anyway (which becomes even worse if you start putting a lot of fuzz in first reflection points.)


----------



## rnrgagne




> Quote:
> Originally Posted by *pepar* /forum/post/20440063
> 
> 
> Open bottom only and not on the "side" wouldn't impede it's performance?
> 
> 
> Jeff



I have to think it would be better than nothing or an untreated soffit.

No matter how I do this room there's going to be compromises, especially since I want to re-use as much of the materials I already have...


----------



## petetwinofpat

let me first start out by saying thanks.....I have been reading this Forum for over 6 months and it has been invaluable....BUT, I am still very confused about how much treatment and how Thick it should be......I have read the acoustical thread for it seems like forever and i am more confused now than when i started...Toole seems to be the person to listen to , than a lot of other people say no.......i just have a few ?


1. how thick should the front wall be....i am, puting oc703 in the front corners for Bass traps, than i am going to insulate the rest of the wall w. HOW THICK ??....my screen is acoustically transparent...


2. my room size is 14 wide up front my right wall goes back 25 ft, than my left wall goes back 14ft and than it goes over 6 feet and back 9 ft, my back wall is 19 ft....my 2nd row will be 3 ft off the back wall so what do i put on the back wall, and how thick should it be?????


3. i was going to treat the side wall w 2" oc 703 upto 50" (ear Level) is this correct.....


floor is totally carpeted, and ceiling has a soffit w lights and fiber optic ceiling in middle.............


thanks in advance for your help....


----------



## nathan_h




> Quote:
> Originally Posted by *petetwinofpat* /forum/post/20444077
> 
> 
> 
> 3. i was going to treat the side wall w 2" oc 703 upto 50" (ear Level) is this correct.....



Not usually. Use the mirror test / method and hit the actual first reflection points.


----------



## gworrel

I am insulating and drywalling my basement where my home theater will go. I just want to make sure that what I am doing will not have any detrimental impact on future acoustical effects.


I have glued 2" XPS foam to the cinder block basement walls. Over that we have screwed 1x3 furring strips 16" oc using tapcon screws. For most of the basement we have screwed 1/2" drywall to the furring strips. We are about to start on the area that will be the side outside wall in the home theater.


In the space where the home theater will go, would there be any benefit to filling the 3/4" space between the furring strips (behind the drywall) with some insulation? Would there be any benefit to double drywall? I am primarily thinking in terms of acoustical effects in the room rather than isolation. Thanks.


Greg


----------



## mtbdudex

Looking for low budget but still decent accuracy here.


3 years ago I bought a Behringer ECM8000 , and use it with a generic Mic cal file downloaded from HTS Behringer ECM8000 Correction Values .


Now, I see PartsExpress has the Dayton Audio EMM-6 (basic same as the ECM8000) http://www.parts-express.com/pe/psho...90-801&scqty=1 , but this one come with its specific unique cal file by mic serial #, for $39 MSRP.
Quote:

The Dayton Audio EMM-6 is a precision electret condenser microphone designed for measurement and critical recording applications. The extremely flat frequency response and true omni-directional polar pattern make it perfect for use with room acoustic analyzers and audio measurement systems. Each microphone includes stand mount, foam windscreen, transport case, and its own unique printed and downloadable calibration response graph and data!

Specifications: Capsule type: 6 mm electret condenser Polar pattern: omni-directional Frequency response: 18 Hz - 20 kHz Impedance: 200 ohms between pins 2 and 3 Sensitivity at 1 kHz into 1K ohm: 10mV/Pa (-40 dBV, re. 0 dB = 1V/Pa) Max SPL for 1% THD @ 1 kHz: 127 dB S/N ratio: 70 dB A-weighted Connector: gold plated XLR Phantom power: +15V to +48V Weight: 144 grams.

New! Download your unique calibration .txt file.

A unique serialized calibration .txt file is available for the EMM-6. Once you receive your microphone, visit daytonaudio.com where you will be prompted to enter the serial number found on the base of your EMM-6. After entering the serial number, your unique calibration .txt file will be available for you to download.
What I'd like to do is buy the PE Dayton Audio EMM-6, load it's cal file into REW5, take some measurements, then swap just the hardware mic to the ECM8000, take same exact measurements, then adjust the cal file for the diff EMM-6 vs ECM8000.

I'd then sell either mic, as what I'd have then is 2 "calibrated" mics.


Q's:

1) Is it easy to adjust the cal file freq by freq?

2) Any tips? Do in excel, side-side before after , then export back as txt for usage?


With the PE mic so "cheap", and time = money, possible I just buy the PE mic and then "give" the ECM8000 to one of my HT enthuasist buddies may be more pratical? As before I was using it for just sub measurements, so the generic HTS cal file sufficed.


It's just that I'm taking more measurememetns, both LFE for subs and also full 20-20khz for room acoustics and want to use a mic with a "real" cal file.

 

splitecm.zip 2.1240234375k . file


----------



## mtbdudex

or, I may instead just spend $109 for this, and then test my current mic against the calibrated mic......., same q's as above:

(cross-spectrum does offer a calibration service for $65 for existing mic owners as well, a 3rd option)
http://www.cross-spectrum.com/measur...behringer.html 


> Quote:
> By popular request, Cross·Spectrum is selling calibrated Behringer ECM8000 microphones. Each microphone has been individually tested against an ANSI-certified reference microphone. Each microphone will be shipped with the following:
> 
> 
> Behringer ECM8000 microphone with windscreen, case, and microphone clip
> 
> Microphone characterization report ( "Basic+" sample/ "Premium+" sample) with individually measured on-axis (0°) frequency response from 5 Hz to 25 kHz
> 
> "Premium" calibrated microphones will also include polar response, sensitivity, and noise floor
> 
> "Basic-Plus" and "Premium-Plus" microphones include frequency response curves at 45° and 90° angles of incidence
> 
> Mini-CD with frequency response data (.FRD format) and polar response data (Excel and .CSV formats, "Premium" calibrated microphones only)
> 
> Prices start at $80 plus shipping for "Basic" calibrated microphones. A feature/price matrix is shown below for the four microphone options we offer.
> 
> 
> 0° Freq. Resp 45°/90° Freq. Resp Polar Meas Noise Floor/Sens. Price Basic ✓ $80 Basic+ ✓ ✓ $85 Premium ✓ ✓ ✓ $95 Premium+ ✓ ✓ ✓ ✓ $100 Prices do not include shipping costs. Domestic shipping is $9 for USPS Priority shipping.



So for $40 from PE I get a mic w/cal file, then at various price points from Cross·Spectrum a mic w/cal file....


----------



## pepar




> Quote:
> Originally Posted by *mtbdudex* /forum/post/0
> 
> 
> What I'd like to do is buy the PE Dayton Audio EMM-6, load it's cal file into REW5, take some measurements, then swap just the hardware mic to the ECM8000, take same exact measurements, then adjust the cal file for the diff EMM-6 vs ECM8000.
> 
> I'd then sell either mic, as what I'd have then is 2 "calibrated" mics.
> 
> 
> Q's:
> 
> 1) Is it easy to adjust the cal file freq by freq?
> 
> 2) Any tips? Do in excel, side-side before after , then export back as txt for usage?
> 
> 
> With the PE mic so "cheap", and time = money, possible I just buy the PE mic and then "give" the ECM8000 to one of my HT enthuasist buddies may be more pratical? As before I was using it for just sub measurements, so the generic HTS cal file sufficed.



Mike, if you value your time at zero, then have at it.










But you should note that the so-called unique calibration file you get for $39 is for the 0° axis, i.e. pointing the mic at the speaker being measured. Many measurements that need to be taken are with a 90° orientation, i.e. the mic pointed at the ceiling.


Just my $.02.


I bought the Dayton with 0°, 45° and 90° calibration files. You probably don't need any more than that.


Jeff


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/20454005
> 
> 
> Mike, if you value your time at zero, then have at it.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> But you should note that the so-called unique calibration file you get for $39 is for the 0° axis, i.e. pointing the mic at the speaker being measured. Many measurements that need to be taken are with a 90° orientation, i.e. the mic pointed at the ceiling.
> 
> 
> Just my $.02.
> 
> 
> I bought the Dayton with 0°, 45° and 90° calibration files. You probably don't need any more than that.
> 
> 
> Jeff



Thx Jeff for quick response; with 3 kids, a dog, ongoing hobbies (HT, photography, etc), yadda-yadda, time is priceless, so I'll spend a few $'s.


Moving on......


[edit] I just ordered from Cross·Spectrum mic w/0°, 45° and 90° calibration files.

I'll still do quick A vs B testing, just for "fun"....


----------



## pepar




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20454152
> 
> 
> Thx Jeff for quick response; with 3 kids, a dog, ongoing hobbies (HT, photography, etc), yadda-yadda, time is priceless, so I'll spend a few $'s.
> 
> 
> Moving on......
> 
> 
> [edit] I just ordered from Cross·Spectrum mic w/0°, 45° and 90° calibration files.
> 
> I'll still do quick A vs B testing, just for "fun"....



What are you using for phantom power? USB pre-amp?


Jeff


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/20454529
> 
> 
> What are you using for phantom power? USB pre-amp?
> 
> 
> Jeff



phantom power via Mobile-pre, computer my 2007 24" iMac, REW5 works fine with that set-up.


Pict here, Mobile-pre sitting on the ground among all the cables.

I use cables connected to the Ext-in to bypass any A/V effects, then also the AuxIn where I can turn EQ on/Off.

Labeling all those cables helps when doing this.


----------



## pepar

I used to eat TV Dinners from tray tables like that when I was a child.


----------



## kevinzoe




> Quote:
> Originally Posted by *petetwinofpat* /forum/post/20444077
> 
> 
> let me first start out by saying thanks.....I have been reading this Forum for over 6 months and it has been invaluable....BUT, I am still very confused about how much treatment and how Thick it should be......I have read the acoustical thread for it seems like forever and i am more confused now than when i started...Toole seems to be the person to listen to , than a lot of other people say no.......i just have a few ?
> 
> 
> 1. how thick should the front wall be....i am, puting oc703 in the front corners for Bass traps, than i am going to insulate the rest of the wall w. HOW THICK ??....my screen is acoustically transparent...
> 
> 
> 2. my room size is 14 wide up front my right wall goes back 25 ft, than my left wall goes back 14ft and than it goes over 6 feet and back 9 ft, my back wall is 19 ft....my 2nd row will be 3 ft off the back wall so what do i put on the back wall, and how thick should it be?????
> 
> 
> 3. i was going to treat the side wall w 2" oc 703 upto 50" (ear Level) is this correct.....
> 
> 
> floor is totally carpeted, and ceiling has a soffit w lights and fiber optic ceiling in middle.............
> 
> 
> thanks in advance for your help....



Hi Pete,

Here's something I wrote over at Audiogon that will answer your questions:


Have you measured the room's frequency response yet? You can use simple test tones (RealTraps has a free and a great file from 10-300Hz) and a Radio Shack SPL meter to see where the problem frequencies lay. Doctors Toole and Olive's research and philosophy with acoustical treatment is to diffuse or absorb reflections that do harm at the listening area and leave alone the ones that do potential good. Everything else can be ignored since they never arrive at the listeners' ears or if they do, they are well below the threshold of harm either in SPL or time delay or both.


The side wall lateral reflections are beneficial - particularly in stereo - since they can produce greater apparent source width and spaciousness, while the front/rear wall reflections can decrease these attributes since they come from the same direction as the direct sound. Try putting bass traps in all 4 corners floor to ceiling and in the middle of the back wall with diffusers on either side of this centre back wall absorber. Also consider placing diffusion in the middle of the front wall (the wall behind the speakers). Side walls should be reflective or diffused at 1st reflection points unless you're into more focused imaging in which case try absorbing the first side-wall reflections. Ceiling can be either diffused or absorbed


Your 2 thick absorbers are too thin. You will need to double or triple them up to get to 4 or 6 thickness so that they behave as a broadband absorber rather than a low-pass filter that throws your speaker's tonal balance off. A generous air space (e.g. 6")is also best to take their effectiveness down to lower frequencies. You need to attenuate the entire spectrum of the reflection which a 2 thick absorber won't achieve - the thicker the better. Come to think of it, you're you considered using a diaphragmatic bass trap rather than the more popular fiberglass filled ones? The diaphragmatic ones hang on the wall and are about 4 thick so are not intrusive on limited floor space of your small sized rooms. They are however more costly. For diffusers for your small room you will need to use ones that you can sit closer to which means types of diffusers that don't offer temporal effects or diffuse in two directions so that only about 50% of the reflections are coming back to you. Examples of these better suited diffusers for small rooms are polyfusers (hemi-cylindrical is a better descriptor), Skyline or 2dimensional QRDs.


You will also likely need parametric EQ to tame the bass peaks that are heard at the listening position and/or multiple subwoofers.


Lastly, a little education on small room physics goes a long way. Pick up Dr Floyd Toole's book and study it.


Good luck


----------



## pepar




> Quote:
> Originally Posted by *kevinzoe* /forum/post/20477922
> 
> 
> 
> Your 2” thick absorbers are too thin. You will need to double or triple them up to get to 4” or 6” thickness so that they behave as a broadband absorber rather than a low-pass filter that throws your speaker’s tonal balance off. *A generous air space (e.g. 6")is also best to take their effectiveness down to lower frequencies.* You need to attenuate the entire spectrum of the reflection which a 2” thick absorber won’t achieve – the thicker the better. Come to think of it, you’re you considered using a diaphragmatic bass trap rather than the more popular fiberglass filled ones? The diaphragmatic ones hang on the wall and are about 4” thick so are not intrusive on limited floor space of your small sized rooms.



Do stood off absorbers need to be open to the fiberglass in the rear, or can they have "backs?" The reason I ask is that I already have 2" 703 panels framed and backed with 1/4" luan that could be stood off if that would help. I could even double the thickness if needed.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20478320
> 
> 
> Do stood off absorbers need to be open to the fiberglass in the rear, or can they have "backs?" The reason I ask is that I already have 2" 703 panels framed and backed with 1/4" luan that could be stood off if that would help. I could even double the thickness if needed.
> 
> 
> Jeff



if you are spacing the panels from the wall, you do not want wood backings on the panels.


----------



## Dennis Erskine

Standing off from the wall surface requires the absorbers be open in the back. The energy must pass through the front of the absorber and be allowed to reflect back through the absorber.


I would disagree with the general statement that 2" is not enough and more is required (as a general statement). First, there are designs and products with a 2" form factor which perform as well as a 4" absorber (within certain frequency ranges). Second, exactly what you need and where you need it is an important consideration. Ideally you'd want all frequencies to decay at the same rate. This does NOT dictate 2", 4" or whatever inch thickness throughout the space. Just laying on 4" throughout runs the very real risk of over absorbing the high frequencies "sucking the life" out of the room


----------



## localhost127




> Quote:
> Originally Posted by *kevinzoe* /forum/post/20477922
> 
> 
> Your 2 thick absorbers are too thin. You will need to double or triple them up to get to 4 or 6 thickness so that they behave as a broadband absorber rather than a low-pass filter that throws your speaker's tonal balance off. A generous air space (e.g. 6")is also best to take their effectiveness down to lower frequencies. You need to attenuate the entire spectrum of the reflection which a 2 thick absorber won't achieve - *the thicker the better.*



thicker the better - up until a certain point. dense material such as OC703 can and will reflect (especially at areas of high angle of incidence) --- however, for broadband absorption to control specular early reflections, too much dense insulation (higher gas flow resistivity) will start to reflect.


as always, you do not necessarily need to 'guess' at how much thickness or air gap you need --- as an ETC graph will detail you whether any specular energy is being reflected above the target attenuation goal for a particular reflection (absorber). the ETC will also tell you if you are seeing reflected energy that may be grazing off the panel, or if the panel insulation itself (if too thick), may be reflecting energy instead of absorbing. the ETC should always be used once the panels are in place to verify that that specific reflection path has been attenuated as needed.


the same is true with corner bass traps (for modal issues) --- as you make thicker and thicker traps, you will want to use material with lower gas flow resistivity.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20479612
> 
> 
> if you are spacing the panels from the wall, you do not want wood backings on the panels.





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20479626
> 
> 
> Standing off from the wall surface requires the absorbers be open in the back. The energy must pass through the front of the absorber and be allowed to reflect back through the absorber.



Thanks, that's what I thought.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20479626
> 
> 
> I would disagree with the general statement that 2" is not enough and more is required (as a general statement). First, there are designs and products with a 2" form factor which perform as well as a 4" absorber *(within certain frequency ranges).*



when in the context of building broadband absorbers to attenuate early reflections (specular energy) - the absorber needs to attenuate *all* of the specular energy (as verified with ETC) - and the design characteristics of the absorber should not need to take into consideration specific frequency ranges...would you agree?




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20479626
> 
> 
> Second, exactly what you need and where you need it is an important consideration. Ideally you'd want all frequencies to decay at the same rate. This does NOT dictate 2", 4" or whatever inch thickness throughout the space. Just laying on 4" throughout runs the very real risk of over absorbing the high frequencies "sucking the life" out of the room



exactly. HF content has little energy and thus is easily absorbed. most of the decay issues within small acoustical spaces are in the modal/wave region, not necessarily specular energy.


Dennis,

do you often see the need for users applying absorption in areas outside of early/first-order reflections? it would seem counter-intuitive for people to cover entire walls with absorption (which is likely only attenuating some mid and all of the HF content...leaving the LF decay issues present which have the most energy and require the most resources/attention) - and sucking precious sonic energy from the room.


it would seem to make sense to apply diffusion in all areas outside of early reflection points --- and early reflection points can be attacked with redirection, absorption, etc... what are your views on users covering entire walls in absorption?? is there ever a time or scenario when you would recommend an entire wall covered with porous absorption? thx


----------



## Dennis Erskine




> Quote:
> when in the context of building broadband absorbers to attenuate early reflections (specular energy) - the absorber needs to attenuate all of the specular energy (as verified with ETC) - and the design characteristics of the absorber should not need to take into consideration specific frequency ranges...would you agree?



I would not fully agree. Assuming absorption is desired (as opposed to diffusion), the problem most commonly occuring is over absorption of the high frequencies (a nasty side effect of standard fiberglass panels).



> Quote:
> it would seem to make sense to apply diffusion in all areas outside of early reflection points --- and early reflection points can be attacked with redirection, absorption, etc... what are your views on users covering entire walls in absorption?? is there ever a time or scenario when you would recommend an entire wall covered with porous absorption?



Hard to say as a general method. It is easy to forget there are 5 or more speakers in a room and getting decay rates settled may require absorption products. Surround speakers are good candidates for diffusion.


----------



## pepar

Dennis, what would your target decay time be for a 13 x 21 x 8 space?


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20481119
> 
> 
> I would not fully agree. Assuming absorption is desired (as opposed to diffusion), the problem most commonly occuring is over absorption of the high frequencies (a nasty side effect of standard fiberglass panels).



i meant to frame the question in regards *only* to areas that are early reflections (not all other areas in the room -- which i then agree with your comment). if one is using absorption to attenuate the early reflection (e.g. broadband panel placed at the first-order reflection point on the boundary) - then we do not care about distinguishing between LF/MF/HF content - as the specular reflection is frequency independent...we only care about attenuating the entire energy of the reflection (ETC graph does not measure frequency, only energy vs time --- and we should not be breaking up specular reflections in terms of frequency; only energy). so, you cannot "over-absorb" HF content at an area of early reflection --- as we are looking to absorb ALL of the energy content within the specular reflection.


but yes, at non-early reflection points --- i agree certainly with your comment. i was just posing the question in context to early reflection points only.


----------



## Dennis Erskine




> Quote:
> HF content at an area of early reflection



Very easily and often done.


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20482303
> 
> 
> Very easily and often done.



Like in most professional mixing stages and studio control rooms?


----------



## danhawk911

Any here have a rough estimate on a room with the dimensions of 18'11 x 14 with two doors how much should i expect to spend to have the room treated in acoustical treatment?


----------



## jcthornton

Dan,


Way too many variables. Here's a few questions you need to answer to determine cost:

1. DIY or pro?

2. Is the room already built, or being done from the ground up with AT in mind?

3. What are your goals for sound transmission, sound volume/pressure, movie/music listening [how critical of a listener are you?]

4. Do you want any certifications for the completed room?

5. Do you want the treatments to be 'hidden' or visible?

6. Any limitations on what can be done (condo rules, etc.?)


I'm sure there are other questions, but depending on your goals, limitations and willingness to do work yourself the cost can range from a few hundred dollars to the tens of thousands - and possibly hundreds of thousands [although this is getting ridiculous and will include the cost of lots of very good equipment]


----------



## mtbdudex




> Quote:
> Originally Posted by *danhawk911* /forum/post/0
> 
> 
> Any here have a rough estimate on a room with the dimensions of 18'11 x 14 with two doors how much should i expect to spend to have the room treated in acoustical treatment?



+1 what jcthorton said, need more info.


For ref, my room is close to your size, 14.5' wide x 18 .5' long x 8.75' high.

I have spent approx......$1k on all my diy materials, includes the oc703/705, fabric covers, etc for my side wall, ceiling panels and my rear/frt wall broadband bass traps.

Worth every penny, now don't ask me how many hours..... Lost count. That does not include measurement equipment.


----------



## pepar

Hey, I thought you were doing measurements?


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> Hey, I thought you were doing measurements?



I am, but I consider the cost of that outta scope , if in scope add say $225 for calibrated mic, stand, cables, mobile pre


----------



## FOH




> Quote:
> Originally Posted by *nathan_h* /forum/post/20482925
> 
> 
> Like in most professional mixing stages and studio control rooms?



+1


I have this same point of contention with Dennis, and try as you might, he will not elaborate with any specificity.


In an area _relatively_ adjacent to the mains, that contains an early, first reflection, mirror point, that is benefited from attenuation of the energy via absorption. I stated "broadband absorption works right there", he said "nope", I said "why", he said "hey look,..there's Elvis"











Look, balance is good, and I know over absorption is all too common. I'm well aware of maintaining an attractive clarity/envelopment equation in a normal listening room. My small mixing/production area is all about clarity. My HT is all about balance and energy management. However, early first mirror points benefit from well executed and focused broadband absorption. This allows enough clarity and image specificity to hear _into the recorded space_. Aside from bass traps, I've found the remainder of the room to be much less important than those first, early, mirror points.




> Quote:
> we only care about attenuating the entire energy of the reflection



Absolutely


Thanks


----------



## Dennis Erskine




> Quote:
> Like in most professional mixing stages and studio control rooms?



ah, yes; but .... most control rooms are set up for near field monitoring. Different beast. Mix and sound stages? ... the good ones are set up with variable acoustics depending on what they are doing.


Speakers can benefit from serious broadband absorption on only those surfaces within 3.5' of the driver's acoustic center (nothing "relative" about it). That is assuming an 80Hz Xover.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20487214
> 
> 
> ah, yes; but .... most control rooms are set up for near field monitoring.



citation???


LEDE and now RFZ do not require near-field monitoring from any documentation ive seen.

if anything, due to the nature of eliminating the most destructive (and usually earliest) early reflection (off the desk/work surface), it is highly recommended that speakers be soffit mounted into the front wall (to eliminate SBIR), or to space the monitors on stands well in front of the desk/work surface (and angle the desk downwards) to eliminate the desk reflection. i have not seen any LEDE workshop documents or RFZ papers that specify either of these control room models require near-field listening only.


RFZ is a model that we emulate with broadband absorption (as true RFZ will use room geometry to redirect the early specular reflections and create the reflection-free-zone).


in small acoustical spaces, absorption (or redirection) at early reflection points clears up the specular freq response (eliminating comb-filtering from constructive/destructive interference of early reflections with the original signal), provides the ISD gap which can then be terminated with haas kicker, and assists with stereo imaging from eliminating the left speaker signal from reflecting off the right wall and entering the right ear. as far as "decreased soundstage width", as some suggests is an effect of attenuating early reflections, i myself haven't experienced this.


i see so many recommendations for people covering their entire walls with broadband absorption (usually far too thin of absorption, which over-absorbs HF content, leaving the mid/LF to create a muddy, boomy room) --- but i'm still looking for a reason when and why you would want to actually cover an entire boundary. if one is looking to normalize the decay times (in the specular region), i dont understand why this would require covering an entire wall. that's the one question i had: when would one cover an entire wall with broadband absorption (assuming the broadband absorption is effective enough to absorb all specular content, not just the HF).



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20487214
> 
> 
> Speakers can benefit from serious broadband absorption on only those surfaces within 3.5' of the driver's acoustic center (nothing "relative" about it). That is assuming an 80Hz Xover.



could you please explain how you have come to this conclusion?


----------



## nathan_h




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20487214
> 
> 
> ah, yes; but .... most control rooms are set up for near field monitoring. Different beast. Mix and sound stages? ... the good ones are set up with variable acoustics depending on what they are doing.
> 
> 
> Speakers can benefit from serious broadband absorption on only those surfaces within 3.5' of the driver's acoustic center (nothing "relative" about it). That is assuming an 80Hz Xover.



Fair enough, in thinking it through, I'd guess all the rooms I have spent a lot of time in for playback and most for mastering fall into this category. So I guess that is part of my bias.


For example: My own personal listening room at present is 13 feet wide, and the FR and FL speakers are spaced about 8 feet apart, forming just about an equilateral triangle with the money seat. We can all do that math and see they are within 3.5' of the side walls.


I'm not sure where "3.5'" comes from, but as I mentally catalog all the domestic listening situations I can recall, and take a look at the galleries here at AVS, I'd say that almost all of them have speakers within 3' or 4' of the side walls. Or in other words, almost all situations people on AVS are working with could benefit from serious broad band first reflection absorption, according to this criteria.


----------



## mtbdudex

I remember reading Dennis refer to this in other posts, and I'm sure others will correct/add, from an older thread:
http://www.avsforum.com/avs-vb/showthread.php?t=798548 



> Quote:
> Originally Posted by *sisaacs* /forum/post/9652240
> 
> 
> I've been reading that with your front speakers/sub if you crossover at 80hz you need to get your front speakers about 3.5 feet away from any wall.
> 
> 
> That's a bit inconvenient for my room 12x16x9, since that would eat up a lot of the room space, so I'm wondering if acoustical treatment allows for more freedom.
> 
> 
> I was currently thinking of doing the general 1" linacoustic over the entire front wall and 4' linacoustic on the sides/back walls. Is this sufficient to allow me to move the speakers closer to the walls without decreasing the sound quality very noticeably?
> 
> 
> If that is sufficient to move them closer, any way to calculate how much closer? For example is 1' sufficient wall-speaker distance with this or is that unreasonable?
> 
> 
> If that's not what would be needed to change the speaker placement without decreasing sound quality, what is needed, or is it simply not possible?
> 
> 
> thanks!





> Quote:
> Originally Posted by *Terry Montlick* /forum/post/9655362
> 
> 
> Actually, it is the front wall which is the issue in this case. The problem is 1/4 wave cancellation.
> 
> 
> Low frequencies emitted from your speakers are omnidirectional. At 80 Hz, the wavelength is (1130 ft/sec)/(80 cycles/sec) ~= 14 ft. When such a wave hits the front wall directly behind the speaker and bounces off, it will be exactly 180 degrees out of phase after traveling 1/2 wavelength, which is ~= 7 ft. To travel that distance, it had to go to the front wall and back, a distance of about 3.5 feet in each direction.
> 
> 
> A 180 degree wave will cancel the original wave, to the extent that it is the same magnitude. The result is a notch in the frequency response. If the reflected magnitude is much less, however, it won't significantly cancel.
> 
> 
> This 1/4 wavelength notch is not horrible. Nor will it even be present if the wall construction absorbs and/or transmits a reasonable amount of 80 Hz sound. But to avoid even the possibility of its existance, a common strategy is to "offload" such a potentially problematic frequency onto the subwoofer by simple choice of crossover frequency and positioning. If the sub is placed closer to the front wall than 1/4 wavelength, it cannot generate a 1/4 wavelength notch.
> 
> 
> - Terry



There are more posts in that thread....


----------



## localhost127

adding to that post by Terry (quoted above) ... the closer to the front wall the driver is placed, the higher the SBIR null = the easier to treat with porous absorption.


----------



## localhost127




> Quote:
> Originally Posted by *nathan_h* /forum/post/20487698
> 
> 
> I'm not sure where "3.5'" comes from, but as I mentally catalog all the domestic listening situations I can recall, and take a look at the galleries here at AVS, I'd say that almost all of them have speakers within 3' or 4' of the side walls. Or in other words, almost all situations people on AVS are working with could benefit from serious broad band first reflection absorption, according to this criteria.



regarding specular energy, it doesn't matter where the speaker is placed in relation to the side walls. the first reflection point (which is likely an early reflection point in small acoustical spaces) can be attenuated fairly easily. there really is no design requirement that im aware of for specular energy except to have the highly directional energy content within the same vertical plane as the listening position (eg tweeter at same vertical level as the ears). but for specular energy, it doesnt matter where the speaker is placed in relation to the boundary, as it merely changes the area of early reflection --- which regardless, will be attenuated either via absorption or redirection (based on other design criteria).


the issue regarding spacing from the boundaries is in the modal/wave region...you will have SBIR issues not only from the front wall, but from the side walls as well (any reflection in the wave region)... and then of course you have LBIR off the rear wall (and possibly side walls) - which also must be taken into consideration. and all of this is added to the existing modal/boundary impedance (real+imaginary) issues .... which becomes even more complex.


but even distance/geometry measurements do not give you concrete data...as it's usually far too complex to even remotely calculate. measurements will show the issues, and then one can play with speaker position (changing along the axis to/from the front wall) to see if a particular null or peak changes in frequency with distance to/from the front wall...then you know that particular trouble spot is from SBIR (or likewise, LBIR from the distance from the listening position to the rear wall).


----------



## nathan_h




> Quote:
> Originally Posted by *mtbdudex* /forum/post/0
> 
> 
> I remember reading Dennis refer to this in other posts, and I'm sure others will correct/add, from an older thread:
> http://www.avsforum.com/avs-vb/showthread.php?t=798548
> 
> 
> There are more posts in that thread....



Well that's interesting and suggests I should move my front speakers closer to the screen wall.


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/20486399
> 
> 
> I meant doing measurements instead of mowing the grass.



ahhh, you were on the "other" forum....same user name, same avatar....might be same guy...

Yes, here is a link to my results of using a Cross-Spectrum Labs calibrated ECM8000 vs non alibrated mic & generic cal file

(I just got the CSL calibrated mic Monday 5/23.)
http://www.hometheatershack.com/foru...tml#post438992 


from that post, some here might find it intresting:


> Quote:
> Well, last night I was able to at least test my 3 year old ECM8000 + generic HTS cal file vs the one I got from Cross-Spectrum Labs (CSL).
> 
> 
> Good news is my prior measurements taken with the 3 year old set-up (in LFE) are pretty close to the CSL one.
> 
> I can say though my original generic ECM8000 HTS mic cal file (from mid-2008) is vastly different for corrections than the recent (Feb-2011 date?) HTS generic ECM8000 mic cal file.
> 
> I was comparing them Monday, I had kept the older one on my work laptop which I originally used for REW before trying REW5 on my iMac.
> 
> 
> This is my IB sub at 2nd row 2nd seat position, no EQ, no Audyssey.
> 
> 
> I did NOT adjust anything at all in REW5.
> 
> 1st graph is "old" set up stock ECM8000 + generic HTS cal file,
> 
> 2nd graph is stock ECM8000 + new CSL cal file (to see the a vs b cal file diff before replacing with new mic),
> 
> 3rd graph is CSL calibrated ECM8000 with its specific cal file (the narrow band 90deg one, as I was taking LFE and pointed at the ceiling).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I then started taking many-many LFE measurements, comparing on my Denon A/V 4308CI Ext-In (sub alone) vs Aux In (RH/LH) diff xover points for mains(40/60/80 hz), diff Audyssey settings, etc.
> 
> You can get "lost" in doing that - in a fun/hobby way, even with putting notes in each measurement box which I do.
> 
> 
> I won't plot those here, I will compare the Mid-Hi freq and plot those later as well though.
> 
> 
> Again, thx CSL for quick turnaround, now I feel confident posting my graphs with a calibrated set-up.
> 
> Well, my RS digital sound level meter is not calibrated....so at worst I'm a few db off from a "datum" point of view, means not much unless you start "bragging" about how much spl your sub outputs, like some people in sub shoot out meets tend to do......(hey, were all friends still, right? Even if my sub kicks you subs ....I digress too much and will stop the banter...)


----------



## localhost127




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20488907
> 
> 
> ahhh, you were on the "other" forum....same user name, same avatar....might be same guy...
> 
> Yes, here is a link to my results of using a Cross-Spectrum Labs calibrated ECM8000 vs non alibrated mic & generic cal file
> 
> (I just got the CSL calibrated mic Monday 5/23.)
> http://www.hometheatershack.com/foru...tml#post438992
> 
> 
> from that post, some here might find it intresting:



in terms of measuring your room for discovering acoustical issues and applying treatments, you do not need an expensive calibrated mic in the sense of accurate dB readings. (for meeting a specific theater reference level, i can understand the need for one). eg, i dont care if a mic is reporting 105dB at 100hz when in actuality it is 103dB --- as long as it is accurate between the relative frequencies that it is measuring.


the above graph, all three measurements (while differing in amplitude), all show relatively the same variance between frequencies.


----------



## pepar




> Quote:
> Originally Posted by *pepar* /forum/post/20481175
> 
> 
> Dennis, what would your target decay time be for a 13 x 21 x 8 space?



From Dec '03, when you were chattier on the subject:



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/0
> 
> 
> I try to keep it in the range of .35 to .40.


 http://archive.avsforum.com/avs-vb/s...55#post2993755


----------



## pepar




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20488907
> 
> 
> ahhh, you were on the "other" forum....same user name, same avatar....might be same guy...
> 
> Yes, here is a link to my results of using a Cross-Spectrum Labs calibrated ECM8000 vs non alibrated mic & generic cal file



I am not able to tell which is 1, 2 or 3, but the real takeaway is how they track so closely. It is a demonstration of +/- xdB tolerance.


Jeff


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/20489239
> 
> 
> I am not able to tell which is 1, 2 or 3, but the real takeaway is how they track so closely. It is a demonstration of +/- xdB tolerance.
> 
> 
> Jeff



Agree Jeff and localhost127 - My simple point in posting is I was pleasantely suprised that my "stock" ECM8000 with its generic cal file (thx CSL for posting that @ HTS) came so close to the calibrated ECM8000 with its specific cal file.

Now, I can sleep with both eyes shut at night, knowing that what I posted prior was decently accurate









Also, I don't really need 2 ECM8000's, so I can sell the "old" one for slight discount from full MSRP, and the person who buys it can have a still mostly accurate mic, decent for HT analysis at least. Hopefully one of my HEMI locals will want to buy it.


----------



## FOH

Quote:

Originally Posted by *Dennis Erskine* 
ah, yes; but .... most control rooms are set up for near field monitoring. Different beast. Mix and sound stages? ... the good ones are set up with variable acoustics depending on what they are doing.


Speakers can benefit from serious broadband absorption on only those surfaces within 3.5' of the driver's acoustic center (nothing "relative" about it). That is assuming an 80Hz Xover.
Thanks Dennis


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *localhost127* /forum/post/20489164
> 
> 
> in terms of measuring your room for discovering acoustical issues and applying treatments...



Some things cannot be measured but must be experienced. I believe the take away messege is that there is a SIGNIFICANT artistic element at work here. Understanding the physics of what is going on is important and necessary, but we have to move beyond the science and blend it with art as well.


----------



## danhawk911




> Quote:
> Originally Posted by *jcthornton* /forum/post/20483643
> 
> 
> Dan,
> 
> 
> Way too many variables. Here's a few questions you need to answer to determine cost:
> 
> 1. DIY or pro?
> 
> 2. Is the room already built, or being done from the ground up with AT in mind?
> 
> 3. What are your goals for sound transmission, sound volume/pressure, movie/music listening [how critical of a listener are you?]
> 
> 4. Do you want any certifications for the completed room?
> 
> 5. Do you want the treatments to be 'hidden' or visible?
> 
> 6. Any limitations on what can be done (condo rules, etc.?)
> 
> 
> I'm sure there are other questions, but depending on your goals, limitations and willingness to do work yourself the cost can range from a few hundred dollars to the tens of thousands - and possibly hundreds of thousands [although this is getting ridiculous and will include the cost of lots of very good equipment]



1.pro

2.being built in brand new house

3. not sure about pressure mostly movie watching.

4.Not really sure about this one.

5. visitable is fine.

6. no rules.


----------



## localhost127




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20492693
> 
> 
> Some things cannot be measured but must be experienced. I believe the take away messege is that there is a SIGNIFICANT artistic element at work here. Understanding the physics of what is going on is important and necessary, but we have to move beyond the science and blend it with art as well.



could you elaborate further?


----------



## pepar

Aesthetics is my guess ...


----------



## SierraMikeBravo

What I mean is, you have to think of the entire process of treatment as a big blob of clay. Say we are trying to make an elephant. I mold the clay so that it takes the shape of an elephant. If I showed it to you, you would say it is an elephant. It has the basic shape...large barrel body, trunk and 4 legs. That is the physics part. Now, I want to add the ears and wrinkles and other details...but suppose I want to embelish a little bit. Add my own flare so to speak because I am going to mold that clay elephant to that which is pleasing to me from my own experience, imagination and creativity. That requires some forethought and vision. I have to always ask the question, "What am I trying to do here"? That is the artistic part. This is my creation...not what a text book tells me it should be. However, getting details right is the time consuming portion and can be frustrating. It can often result in making my elephant look worse (or in this case sounding worse). In the end, the proportions of my elephant can be measured to say that it is precise and accurate to scale, but the details cannot be measured analytically.


THEN we can get into aesthetics...completely seperate issue altogether. Being able to blend physics, abstractly molding the sound to something I like or the client likes AND making it all look great can be challenging. The point here is that there is more to treating a room than just looking at a plot. However, as always, beauty is in the eye...errr...the ear of the beholder.


----------



## nathan_h

I guess I am confused too because that elephant metaphor doesn't help me understand which elements you are talking about. Is there a non elephant example? 


I do believe there are things that matter that we don't usually or perhaps can't well measure.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *nathan_h* /forum/post/20493870
> 
> 
> I do believe there are things that matter that we don't usually or perhaps can't well measure.



See! The elephant metaphor worked!







You got it!


----------



## erkq

Without measuring, what are the subjective measures of success? What is everyone looking for? Clarity? Spaciousness? Localization? What else? I guess I'm trying to figure out how much of a return I'll get if I start measuring.


Maybe I lucked out, maybe I'm ignorant... I dunno... but I'm extremely happy with the results of absorption behind an AT screen and on 1st reflection points. The quietest whisper is easily intelligible and LOST feels like the room opens up and you are in the jungle. Seems like I have clarity and spaciousness. Of course the frequency response SEEMS good. Highs are present without being "screechy" and the IB sub rocks your world. With an AT screen, sounds are well localized too. The sound system simply disappears. Frankly, I just don't think about it much... it doesn't draw attention to itself.


I am fortunate (I think) to have a 17' cathedral ceiling with 6/12 pitch that runs across the theater about 2/3 back from the screen. Seems to avoid harmful ceiling reflections.


----------



## nathan_h




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20493990
> 
> 
> See! The elephant metaphor worked!
> 
> 
> 
> 
> 
> 
> 
> You got it!



Well, I get the concept, but don't have a single example to point to. Can you describe one key thing that matters for acoustically improving a room, that cannot be measured?


The reason I get the concept is that I have listened to gear that measures the same, but sounds different. It may be the placebo effect. But I sort of don't care, if it works for me. For example, if my attention tends to wander with some d/a converter versus another, I choose the one that holds my attention. Can I measure that with tools? No. Is it real? Maybe not. But I can say I am happier with one versus the other and even if it's all in my head, I'm not sure that's any reason to ignore the way I feel when listening to a particular piece of gear.


So can you describe something about room treatment that illustrates a key feature that cannot be measured but that makes a difference in terms of satisfaction?


----------



## localhost127




> Quote:
> Originally Posted by *nathan_h* /forum/post/20493870
> 
> 
> I do believe there are things that matter that we don't usually or perhaps can't well measure.



i must have missed the commentary where anyone insinuated against this statement or train of thought?


----------



## localhost127




> Quote:
> Originally Posted by *erkq* /forum/post/20494253
> 
> 
> Without measuring, what are the subjective measures of success? What is everyone looking for? Clarity? Spaciousness? Localization? What else? I guess I'm trying to figure out how much of a return I'll get if I start measuring.
> 
> 
> Maybe I lucked out, maybe I'm ignorant... I dunno... but I'm extremely happy with the results of absorption behind an AT screen and on 1st reflection points. The quietest whisper is easily intelligible and LOST feels like the room opens up and you are in the jungle. Seems like I have clarity and spaciousness. Of course the frequency response SEEMS good. Highs are present without being "screechy" and the IB sub rocks your world. With an AT screen, sounds are well localized too. The sound system simply disappears. Frankly, I just don't think about it much... it doesn't draw attention to itself.
> 
> 
> I am fortunate (I think) to have a 17' cathedral ceiling with 6/12 pitch that runs across the theater about 2/3 back from the screen. Seems to avoid harmful ceiling reflections.



sure. but often people get to a point and think that is good enough or that is the best it gets; which is entirely fair. design constraints are design constraints. however, there are other levels to get to, which will make noticable increases even after your room already has some basic treatment.


im reminding of Andreas' commentary in this thread:
http://www.gearslutz.com/board/studi...s-trigger.html 


"The before/after is startling. To say the least. *Feels like I've done the same sort of upgrade that I did when going from no treatment to well treated room.."*


----------



## erkq




> Quote:
> Originally Posted by *localhost127* /forum/post/20494750
> 
> 
> im reminding of Andreas' commentary in this thread:
> http://www.gearslutz.com/board/studi...s-trigger.html
> 
> 
> "The before/after is startling. To say the least. *Feels like I've done the same sort of upgrade that I did when going from no treatment to well treated room.."*



Thanks... thanks loads... I KNEW I should have stayed ignorant. What an interesting read! There's lots to absorb (puny). I'll have to go through it several times. Seriously, thanks for responding with this.


----------



## localhost127




> Quote:
> Originally Posted by *erkq* /forum/post/20495404
> 
> 
> Thanks... thanks loads... I KNEW I should have stayed ignorant. What an interesting read! There's lots to absorb (puny). I'll have to go through it several times. Seriously, thanks for responding with this.



here is the thread where the community walked through schroeder's principles --- and the process of collio compiling QRDUde









it's an old (but epic) thread. if you read it you are essentially replaying the troubleshooting/discovery process for building QRDude as well as learning everything you want to know about QRDs. it's a huge learning process to follow their conversations as they are troubleshooting and discussing the principles.


this thread is ****ing epic. dedicate a full day to reading and absorbing it.
http://www.gearslutz.com/board/bass-...-possible.html 


!##################################################

!##################################################

!##################################################

!##################################################



here is the most important thread regarding absorption:
http://www.gearslutz.com/board/studi...q-4-avare.html 


!##################################################

!##################################################

!##################################################

!##################################################



more of SAC's brilliant commentary:
http://www.gearslutz.com/board/bass-...absorbers.html 


!##################################################

!##################################################

!##################################################

!##################################################



envelop time curve
http://www.gearslutz.com/board/studi...c-impulse.html


----------



## FOH

Localhost,...superb information.., many thanks, much to assimilate


----------



## mtbdudex




> Quote:
> Originally Posted by *FOH* /forum/post/0
> 
> 
> Localhost,...superb information.., many thanks, much to assimilate



+100! I'm attending wedding in south Carolina this weekend, just got to hotel room after 13hr drive from Michigan.

Thx for my reading assignment!


I'll turn in my essay when done.


----------



## nathan_h




> Quote:
> Originally Posted by *localhost127* /forum/post/20494719
> 
> 
> i must have missed the commentary where anyone insinuated against this statement or train of thought?



This being AV "Science" I'm assuming that anything that cannot be measured is suspect.


But more to the point: I'm still waiting for an example of what matters in room treatment but cannot be measured. I believe based on other cases where I have experienced this that such a thing can be true. I'd like to know more than just that there is some "art" involved.


----------



## jamin

Hmm --

I can suggest situations where can't be measured is perhaps not quite true, but failing metrics for comparison, or needing some form of not readily available post-processing, or requiring inordinate known processing and still failing a metric would render the data acquisition aspect nearly moot.


Some examples:

Using ipsilateral and contralateral treatments for ASW and envelopment modification.


Realizing a hole exisits in the surround envelopment field and knowing that adding some diffusion in a particular region will mitigate the hole.


Certainly measurements can be made before and after but often the interpretation can be up for grabs since there are no metrics.


Maybe a better phrase is crafting the sound which, i believe includes both elemets of the science and art of applicaton.


Hmm...

Grabbing a copy of Toole's book allows one a huge set of references containing enough material to keep a fellow busy for a while.


----------



## nathan_h

I like Toole's book but so many of the studieshe cites use listener peference as a metric, rather than reference to industry standards and achieving them, that his conclusions have to be taken in that context.


But I like your surround diffusion example. I think I see what you are getting at.


----------



## jamin

I believe the lack of industry standard is the reason for Toole's use of the phrase "Circle of confusion".


----------



## scooter_29

I have a crazy question. If I have 6" of 703 behind a piece of plywood... have I entirely defeated its bass absorbing abilities? I don't want to wrap the 703 in fabric as it doesn't work in my room's decor.


----------



## pepar




> Quote:
> Originally Posted by *scooter_29* /forum/post/20500350
> 
> 
> I have a crazy question. If I have 6" of 703 behind a piece of plywood... have I entirely defeated its bass absorbing abilities? I don't want to wrap the 703 in fabric as it doesn't work in my room's decor.



You're right, that is crazy.


----------



## pepar




> Quote:
> Originally Posted by *jamin* /forum/post/20500045
> 
> 
> I believe the lack of industry standard is the reason for Toole's use of the phrase "Circle of confusion".



"Ball of confusion" was taken.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/20500915
> 
> 
> You're right, that is crazy.



Why would it be crazy? In fact, placing plywood in front of the absorption material...depending on the properties of the plywood and mounting methods...could actually improve bass absorption performance (subject to meaurment of course and placement). Keep in mind the wavelength of the "bass" frequencies. Generally, in order to fully attenuate lower frequencies we aim for a thickness of 1/4 the wavelngth of that frequency (although 1/10 has been known to work in some cases). Now, I am not saying that if it is not 1/4 the wavelength it will be useless. In this case, the plywood would act as a membrane, and depending on the type of mounting, could enhance the bass absorption effect...or it could be a problem as well. This is where measurement would in fact be quite useful. By placing the plywood in front of the porous material, you have in fact tuned the absorber to target specific frequencies. Don't be afraid to experiment with placing "things" in front of the absorption and see what it does. Personally, I can think of better things to place in front of the broadband absoprtion than plywood in most cases (not all...just depends on what you are trying to do), but I like the way he is thinking.


----------



## scooter_29




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20501052
> 
> 
> Why would it be crazy? In fact, placing plywood in front of the absorption material...depending on the properties of the plywood and mounting methods...could actually improve bass absorption performance (subject to meaurment of course and placement). Keep in mind the wavelength of the "bass" frequencies. Generally, in order to fully attenuate lower frequencies we aim for a thickness of 1/4 the wavelngth of that frequency (although 1/10 has been known to work in some cases). Now, I am not saying that if it is not 1/4 the wavelength it will be useless. In this case, the plywood would act as a membrane, and depending on the type of mounting, could enhance the bass absorption effect...or it could be a problem as well. This is where measurement would in fact be quite useful. By placing the plywood in front of the porous material, you have in fact tuned the absorber to target specific frequencies. Don't be afraid to experiment with placing "things" in front of the absorption and see what it does. Personally, I can think of better things to place in front of the broadband absoprtion than plywood in most cases (not all...just depends on what you are trying to do), but I like the way he is thinking.



I have Magnepan MG-20.1s and broad absorption behind the speakers helps with the low frequencies but does more damage to the rest of the sound than the bass absorption is worth. So, I am trying to find a way to get bass absorption without the high frequency absorption.


Second, I really cannot stand the look of fabric. I was hoping that a veneered sheet of 1/2 to 3/4" plywood in front of the 703 would still allow bass absorption.


And one other problem... on one side is an electric panel that I need access to. I was going to make these http://www.ethanwiner.com/BTPlans.gif but the electrical panel causes a huge problem. So.... I am looking for alternatives.


----------



## SierraMikeBravo

Give it a try! Stick a piece of varying thickness plywood at various depths from the absorption....listen...measure...rinse and repeat!


----------



## scooter_29




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20501159
> 
> 
> Give it a try! Stick a piece of varying thickness plywood at various depths from the absorption....listen...measure...rinse and repeat!



Somehow I knew you were going to say that!







Its a lot of 703 and plywood to buy for an experiment. Its a big space... the two areas in question behind the speakers are 9' high X 4' wide each. Before I went to the effort, I was hoping to get a sense as to whether it was a waste of time and money.


----------



## pepar




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20501052
> 
> 
> Why would it be crazy? ...depending on ...could actually improve ... subject to meaurement of course and placement ... ... depending on the type of mounting, could enhance the bass absorption effect...or it could be a problem as well.
> 
> 
> Personally, I can think of better things to place in front of the broadband absoprtion than plywood in most cases (not all...just depends on what you are trying to do), but I like the way he is thinking.



I know the OP's post was not chocked full of details, but I got the impression that there was nothing on his mind but hiding the 'glass. And it seems like a lot of work, especially for a non-acoustician, to find just the right plywood mounted in just the right way.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *scooter_29* /forum/post/20501174
> 
> 
> Somehow I knew you were going to say that!
> 
> 
> 
> 
> 
> 
> 
> Its a lot of 703 and plywood to buy for an experiment. Its a big space... the two areas in question behind the speakers are 9' high X 4' wide each. Before I went to the effort, I was hoping to get a sense as to whether it was a waste of time and money.



There are a LOT of different fabrics that you could use to cover the 703 ... lots of different colors, and some with different patterns, too. I have seem fabric chosen that so closely matched the wall color that the traps almost disappeared. One guy built them square and, tucked into the corners, looks like an architectural detail that is a continuation of his soffit.


Just tossing that out there ....


Jeff


----------



## scooter_29




> Quote:
> Originally Posted by *pepar* /forum/post/20501198
> 
> 
> There are a LOT of different fabrics that you could use to cover the 703 ... lots of different colors, and some with different patterns, too. I have seem fabric chosen that so closely matched the wall color that the traps almost disappeared. One guy built them square and, tucked into the corners, looks like an architectural detail that is a continuation of his soffit.
> 
> 
> Just tossing that out there ....
> 
> 
> Jeff



The walls in question are being paneled as well as having cabinetry on them. Fabric in any form unfortunately isn't an option.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/20501189
> 
> 
> I know the OP's post was not chocked full of details, but I got the impression that there was nothing on his mind but hiding the 'glass. And it seems like a lot of work, especially for a non-acoustician, to find just the right plywood mounted in just the right way.
> 
> 
> Jeff



There are certainly less painful methods.


----------



## pepar




> Quote:
> Originally Posted by *scooter_29* /forum/post/20501259
> 
> 
> The walls in question are being *paneled as well as having cabinetry on them.* Fabric in any form unfortunately isn't an option.



Then I'd say that they are not going to be part of your acoustical treatment package.










Jeff


----------



## LarryChanin




> Quote:
> Originally Posted by *scooter_29* /forum/post/20501259
> 
> 
> The walls in question are being paneled as well as having cabinetry on them. Fabric in any form unfortunately isn't an option.



Hi,


Got tons of money?









Topperfo® Micro 

RPG website 


Larry


----------



## scooter_29




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20501506
> 
> 
> Hi,
> 
> 
> Got tons of money?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Topperfo® Micro
> 
> RPG website
> 
> 
> Larry



Very interesting!


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20501506
> 
> 
> Hi,
> 
> 
> Got tons of money?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Topperfo® Micro
> 
> RPG website
> 
> 
> Larry



Ah, shucks! Larry beat me to it!


----------



## LarryChanin




> Quote:
> Originally Posted by *scooter_29* /forum/post/20501943
> 
> 
> Very interesting!



Hi,


There's also a grooved wood panel.

Topakustik 


Maybe Shawn or Dennis can give you an idea of how much these two types of wood panels cost.


Larry


----------



## LarryChanin




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20502002
> 
> 
> Ah, shucks! Larry beat me to it!



Hi Shawn,


Good to "talk" to you again.


I don't know whether the RPG folks will even talk to DIYers. I can't remember what I was interested at the time, but about 7 years ago when I was building my home theater they wouldn't even respond to me.


I guess they are used to dealing with professional installers or architects.


Frankly, these particular products really need a professional to spec out the particular design and perhaps even do the installation correctly. I doubt this is a job for your average carpenter.










Larry


----------



## scooter_29




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20502101
> 
> 
> Hi Shawn,
> 
> 
> Good to "talk" to you again.
> 
> 
> I don't know whether the RPG folks will even talk to DIYers. I can't remember what I was interested at the time, but about 7 years ago when I was building my home theater they wouldn't even respond to me.
> 
> 
> I guess they are used to dealing with professional installers or architects.
> 
> 
> Frankly, these particular products really need a professional to spec out the particular design and perhaps even do the installation correctly. I doubt this is a job for your average carpenter.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Larry



I am not your average carpenter







All I will need is the hole pattern.


----------



## Dennis Erskine

Believe me .... those panels are not cheap! I don't have the pricing in front of me; but, I did look at those seriously for a project a few years ago for a studio and office and they were price prohibitive


----------



## scooter_29




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20502676
> 
> 
> Believe me .... those panels are not cheap! I don't have the pricing in front of me; but, I did look at those seriously for a project a few years ago for a studio and office and they were price prohibitive



I don't doubt it... However, I am waiting to take delivery of a CNC router this summer and it would be a piece of cake to fabricate them as long as I knew the hole spacing and size. Material cost would be just a few hundred dollars... but than again, you need the CNC machine too.


----------



## localhost127

a good conversation going on regarding HT surrounds. this commentary by jhbrandt should be explored and discussed further.


his diagram:


http://imgur.com/xzMXi.jpg%5B/IMG%5D



discussion:
http://www.gearslutz.com/board/studi...chunks.html#23


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *scooter_29* /forum/post/20503274
> 
> 
> I don't doubt it... However, I am waiting to take delivery of a CNC router this summer and it would be a piece of cake to fabricate them as long as I knew the hole spacing and size. Material cost would be just a few hundred dollars... but than again, you need the CNC machine too.



Hole spacing and depth is proprietary and will likely not be divulged...not to mention copyright infringement.







There is also more going on than meets the eye here as well regarding materials. Hate to be the party pooper, it is what it is, but I also support it since the amount of math, engineering and testing that went into designing such panels is quite extensive and expensive. They deserve to get out of it what they put into it IMHO.


----------



## localhost127

i believe d'antonio and cox's AA&D had a fairly detailed section, but i haven't had it in front of me for some time and cannot confirm.

check your local library?

http://www.amazon.com/Acoustic-Absor...6878681&sr=1-1


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *localhost127* /forum/post/20509839
> 
> 
> i believe d'antonio and cox's AA&D had a fairly detailed section, but i haven't had it in front of me for some time and cannot confirm.
> 
> check your local library?
> 
> http://www.amazon.com/Acoustic-Absor...6878681&sr=1-1



Yes they do, but there a many things they don't divulge. Chris Karikakis and Sunhil Baritkahr also wrote a master's level text that hint at a few of the elements of Audyssey, but certainly the equational derivations and implementation are left up to the reader.


----------



## scooter_29




> Quote:
> Originally Posted by *SierraMikeBravo* /forum/post/20510021
> 
> 
> Yes they do, but there a many things they don't divulge. Chris Karikakis and Sunhil Baritkahr also wrote a master's level text that hint at a few of the elements of Audyssey, but certainly the equational derivations and implementation are left up to the reader.



Except that A) its not copyright infringement. B) The materials used are posted on their website (16MM Class A rated MDF) and C) And if they happened to have patented it, like they did with the BAD panels, the information is in the public domain.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *scooter_29* /forum/post/20510069
> 
> 
> Except that A) its not copyright infringement. B) The materials used are posted on their website (16MM Class A rated MDF) and C) And if they happened to have patented it, like they did with the BAD panels, the information is in the public domain.



Yep, good catch! Don't know why I was thinking copyright.







Getting old I guess. Best wishes!


----------



## Roger Dressler




> Quote:
> Originally Posted by *localhost127* /forum/post/20509007
> 
> 
> a good conversation going on regarding HT surrounds. this commentary by jhbrandt should be explored and discussed further.



From my read of the interesting thread, that diagram is explicitly not for home theaters, according to its designer.


----------



## localhost127




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20510342
> 
> 
> From my read of the interesting thread, that diagram is explicitly not for home theaters, according to its designer.



correct - i didnt think that solution applied to the general crowd here (hence phrasing it for HT playback discussion). curious to thoughts?


----------



## pepar

OK, why would this design be good for creating mixes but not for playing them back in a home theater???


Jeff


----------



## cuzed2

Jeff,
_Sent you a PM yesterday about an REW soundcard - Thanks in Advance for your input._

Now back to our regularly scheduled thread...


----------



## cuzed2

Jeff - Thanks Again!

Thread Hi-Jack is now concluded


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/20510410
> 
> 
> OK, why would this design be good for creating mixes but not for playing them back in a home theater???



It is apparently useful in emulating the diffuse character of a theater or dubbing stage. It would therefore help when doing mixes or predubs that will find their way to those larger rooms, so as to avoid surprising differences in aesthetics.


It was mentioned about adding some background noise to help mask low level details, again to help predict the theatrical result. Probably would be better to run the audio thru some room modeling software with impulse responses from a real theater, so as to get the room decay into the equation.


If you want to replicate the disadvantages of theatrical acoustics at home, there are lot of solutions available, from THX dipoles to cinema DSP.


----------



## jchusky77

I'm in the process of making panels. When choosing cloth for the covers, are there certain things to look for? For instance thickness of the fabric?


----------



## erkq




> Quote:
> Originally Posted by *jchusky77* /forum/post/20512730
> 
> 
> I'm in the process of making panels. When choosing cloth for the covers, are there certain things to look for? For instance thickness of the fabric?



Acoustic transparency... either by specification of the fabric like some GOM fabric, or by the "breath test" where you blow on it and see if the air goes through relatively unimpeded.


----------



## Norman Varney

With our Frequency Response Panel (FRP) system we are often asked this question and reply, in part, with the following information:


Fabric contenders will be similar to speaker grill cloth. Look for weights around 9-13oz. per linear yard and >65% polyester content. Primary use may say for panels and upholstered walls. Here are a few tests you can use to evaluate a custom fabric contender:

1. When holding the fabric in front of your eyes, you should be able to easily identify objects across the room.

2. When holding the fabric with a spread-fingered hand against your lips and blowing through it, you should be able to feel air passing by your fingers.

3. When pulling on the fabric, it should not exhibit any elasticity.


Fabrics can be acoustically verified via air-flow resistivity or impedance tube tests depending on the function of the cloth i.e.; covering a speaker or covering an acoustic panel.


For installation, understand values for rip, grab, sag and track hold. Fabrics will be tested for elasticity, retainer hold, tensile strength, tear strength, pattern alignments concerns, read-through concerns and light reflectivity concerns.


Understand that just because a fabric is porous enough to see through or pass air through, does not mean is is acoustically friendly. Every type of fabric absorbs and reflects energy uniquely. This noise reduction coefficient needs to be understood in order to control the sound quality of the room properly.


----------



## pepar




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20511184
> 
> 
> 
> If you want to replicate the disadvantages of theatrical acoustics at home, there are lot of solutions available, from THX dipoles to cinema DSP.



Not in agreement, I take it, with the thinking behind single dipoles for surrounds? Or have the mixes changed since then and now more direct radiated sound is more correct?


I will toss out there that I recently "discovered" my M&K's "Tripole" mode and that has made a big difference. In my case, more output from the monopole portion "goes over the head" of the near seat to the far seat, and correspondingly reduces the dipole component of the speaker's output (and the level of the surround at the near seat). Things are still peachy in the center seat with a touch more localizing of surround content, but now the surrounds are more enjoyable at the left and right seats as well.


Jeff


----------



## nathan_h

Mixes are still all over the place. A lot of older DVDs still contain the theatrical mix, which is too sibilant and will sound most correct with the old fashion THX surround recommendations (diffuse).


More and more home video releases are mixed for small rooms and direct radiating speakers all around.


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/20513528
> 
> 
> Not in agreement, I take it, with the thinking behind single dipoles for surrounds? Or have the mixes changed since then and now more direct radiated sound is more correct?



I would not say the mixes have changed fundamentally, the surrounds still carry ambience, music and effects. And no, I never got on the dipole wagon. Tried them several times, but the inability to timbre match them with the fronts bothered me--I could not feel I was in one seamless space, but in a splicing of distinct front plus rear spaces.


Theaters have line arrays for very good reasons of audience coverage. But I'm not out to replicate theatrical sound in my home theater. I want to hear the soundtrack as cleanly and clearly as possible, in a single, seamless, contiguous space-time continuum. I find 7.1 works really well, direct radiators all around, for movies and also for music, which is the majority of my listening.



> Quote:
> I will toss out there that I recently "discovered" my M&K's "Tripole" mode and that has made a big difference. In my case, more output from the monopole portion "goes over the head" of the near seat to the far seat, and correspondingly reduces the dipole component of the speaker's output (and the level of the surround at the near seat). Things are still peachy in the center seat with a touch more localizing of surround content, but now the surrounds are more enjoyable at the left and right seats as well.



I like the idea of the Tripole. Wouldn't it be cool to have a surround processor that could feed the diffuse parts of the sound to the dipole drivers and the direct sounds to the monopole?


----------



## LarryChanin




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20516045
> 
> 
> I would not say the mixes have changed fundamentally, the surrounds still carry ambience, music and effects. And no, I never got on the dipole wagon. Tried them several times, but the inability to timbre match them with the fronts bothered me--I could not feel I was in one seamless space, but in a splicing of distinct front plus rear spaces.
> 
> 
> Theaters have line arrays for very good reasons of audience coverage. But I'm not out to replicate theatrical sound in my home theater. I want to hear the soundtrack as cleanly and clearly as possible, in a single, seamless, contiguous space-time continuum. I find 7.1 works really well, direct radiators all around, for movies and also for music, which is the majority of my listening.
> 
> 
> I like the idea of the Tripole. *Wouldn't it be cool to have a surround processor that could feed the diffuse parts of the sound to the dipole drivers and the direct sounds to the monopole?*



Hi Roger,


This touches on a subject that came up in the Audyssey thread. Some folks were complaining that with DSX processing they weren't hearing their surrounds as distinctively. In an earlier posting Chris K mentioned that DSX involves decorrelating the surrounds and I wondered if that was what the folks were reacting to. In today's movies, particularly action movies, there is a significant portion of direct sounds as well as diffuse sounds in the surrounds and if decorrelation is being applied ideally it should only be applied to the diffuse sounds. Is there a way to selectively decorrelate sounds? Does THX Adaptive Decorrelation do this?


Thanks.


Larry


EDIT:

I did a little Googling on THX Adaptive Decorrelation and found this in the Audio Dictionary, by White & Louie.



> Quote:
> *Adaptive Decorrelation*
> 
> A DIGITAL SIGNAL PROCESSING (DSP) circuit found in Dolby Digital 5.1 decoders for use in home theater sound systems that takes the surround signal, which may be monaural, and drives two signals to feed the surround speakers. The decorrelation process adds diffusion to the sound field to prevent its being localized at the speaker locations, which would occur if the monaural signal were fed directly to the surround speakers. If the surround channels are in stereo, the decorreclation circuit is automatically disabled. Adaptive Decorrelation is a registered trademark of THX LTD.



So this wasn't what I was looking for.


Getting back to Roger's remarks, are there existing signal processing technologies that permit isolating diffuse sounds from direct sounds in a soundtrack?


----------



## mtbdudex

Quote:

Originally Posted by *pepar* 
Not in agreement, I take it, with the thinking behind single dipoles for surrounds? Or have the mixes changed since then and now more direct radiated sound is more correct?


I will toss out there that I recently "discovered" my M&K's "Tripole" mode and that has made a big difference. In my case, more output from the monopole portion "goes over the head" of the near seat to the far seat, and correspondingly reduces the dipole component of the speaker's output (and the level of the surround at the near seat). Things are still peachy in the center seat with a touch more localizing of surround content, but now the surrounds are more enjoyable at the left and right seats as well.


Jeff
Quote:

Originally Posted by *Roger Dressler* 
I would not say the mixes have changed fundamentally, the surrounds still carry ambience, music and effects. And no, I never got on the dipole wagon. Tried them several times, but the inability to timbre match them with the fronts bothered me--I could not feel I was in one seamless space, but in a splicing of distinct front plus rear spaces.


Theaters have line arrays for very good reasons of audience coverage. But I'm not out to replicate theatrical sound in my home theater. I want to hear the soundtrack as cleanly and clearly as possible, in a single, seamless, contiguous space-time continuum. I find 7.1 works really well, direct radiators all around, for movies and also for music, which is the majority of my listening.


I like the idea of the Tripole. Wouldn't it be cool to have a surround processor that could feed the diffuse parts of the sound to the dipole drivers and the direct sounds to the monopole?








Interesting discussion tucked away in the Master acoustics thread...

When I bought my set-up Dec-2007 seemed most people were still recommending dipole surrounds, so I got mid-level Paradigm Monitor 9 speakers for my 7.1 set-up, with (4) of their ADP-390 for side and rear surrounds.
http://www.paradigm.com/products/par...series/adp-390 










Now, my brother inlaw just outfitted his HT with Monitor Audio Gold series, and his surrounds are their GSFX surrounds, which have a dual mode configuration (dipole or monopole) so you can pick and choose.

They even state "The GSFX is ‘ambidextrous' meaning the speaker can be configured as right or left "handed" during installation (via front panel switch) so the polarity of the front speakers is in phase with the GSFX surrounds. "

You can see the switch on front face in this picture:
http://www.monitoraudiousa.com/produ...x/your-speaker 










So, where I'm going with this is from Jan-2008 thru Feb-2011 I did not have any acoustic treatments, now I've added side/ceiling RFZ panels.

Nothing specifically on the rear portion, so I still have that similar ambiance from the dipole config, but I have to wonder if I'm "missing something"..


Seems like most of the dipole manuf should at least add a switch like Monitor Audio/others have done, and let the end user choose based on their preference and listening material.


I've toyed with the idea of replacing the rear ADP-390's on the back wall with the Paradigm Titan Monitor, keeping the side surrounds as ADP-390's.

Or.....re-wiring the rear ADP-390's so instead of the sides being out of phase and creating a null along their axis if both are in-phase then that would give more "forward" coverage, in effect like a monopole switch on the Monitor Audio GSFX's.....

yea, I should probably move this thought to one of the speaker forums or audio set-up theory forums....but it was brought up here and got my mind churning...


----------



## Dennis Erskine

I'm not going to agree entirely with Roger, nor entirely disagree. Each has their place and proper application. Certainly monopoles can be made to work in a small room with a single (maybe two) listening positions. They aren't going to be timbre matched unless they are the same distance as the mains from all boundaries and at the same height. (The timbre, as heard in the listening position, will change with height on a monopole design.) Once you have a small room with, say, two rows of seats and three to four seats in each row, monopoles can easily create a bigger problem than they solve. Other than timbre, you now have a situation where those on the ends of the rows are overwhelmed with that nearest side surround ... in other words, ears are soooo close to their respective side surround speaker, that speaker will over power the rears and opposite side speakers.


In larger rooms, with multiple rows, a relatively respectable distance between the end seats and the walls and the luxury of surrounds for each row, now you can create something really stunning with an array of monopole surrounds.


In the end, saying one is better than the other without context is not entirely correct. That's, of course, my opinion. Take it, leave it, or roll your own.


----------



## Roger Dressler




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20516393
> 
> 
> Getting back to Roger's remarks, are there existing signal processing technologies that permit isolating diffuse sounds from direct sounds in a soundtrack?



While I do not know for sure, I suspect that such is part of Neo:X. Only because the creators of that have discussed the benefits of such processing in AES papers. I realize that cannot be taken as anything other than mere speculation at this point. With Onkyo's announcement, it might not be too long until we find out.


----------



## Roger Dressler




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20522688
> 
> 
> I'm not going to agree entirely with Roger, nor entirely disagree.
> 
> 
> In the end, saying one is better than the other without context is not entirely correct. That's, of course, my opinion. Take it, leave it, or roll your own.



I hope everyone understood my post as expressing nothing more than my personal opinions and preferences.


----------



## LarryChanin




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20522688
> 
> 
> Certainly monopoles can be made to work in a small room with a single (maybe two) listening positions. They aren't going to be timbre matched unless they are the same distance as the mains from all boundaries and at the same height. (The timbre, as heard in the listening position, will change with height on a monopole design.)



Hi Dennis,


With regard to timbre matching surrounds to the front speakers, a long time ago I thought recalled that you stated that due to the fact that surrounds are positioned to the sides or rear of the listener, even if they were identical to the mains, that they could never completely match in timbre. I have I expressed this correctly?



> Quote:
> In larger rooms, with multiple rows, a relatively respectable distance between the end seats and the walls and the luxury of surrounds for each row, now you can create something really stunning with an array of monopole surrounds.



Can you give us a rough idea of an acceptable distance between the end seats and the monopole surrounds?


Larry


----------



## Electric_Haggis




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20517091
> 
> 
> Interesting discussion tucked away in the Master acoustics thread...
> 
> When I bought my set-up Dec-2007 seemed most people were still recommending dipole surrounds, so I got mid-level Paradigm Monitor 9 speakers for my 7.1 set-up, with (4) of their ADP-390 for side and rear surrounds.
> 
> ...



For the record, there's a great thread here that deals exclusively with dipoles, bipoles, quadpoles, etc...

http://www.avsforum.com/avs-vb/showthread.php?t=874378


----------



## Roger Dressler




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20523078
> 
> 
> With regard to timbre matching surrounds to the front speakers, a long time ago I thought recalled that you stated that due to the fact that surrounds are positioned to the sides or rear of the listener, even if they were identical to the mains, that they could never completely match in timbre. I have I expressed this correctly?



Not Dennis, but one could say that HRTFs heavily influence the spectral balance for each speaker position. No matter, human brains don't interpret that as a timber shift, but as a directional shift.


Anyway, the point I was making about timbre matching was aimed at what is coming out of the speakers. Identical speakers in a room that avoids degrading the responses is what I would qualify as timbre matched. And it is indeed achievable with monopoles (and judicious EQ and acoustic care) whereas with dipoles it simply is not.


----------



## mbfleming

It was Floyd E Toole that said that. See this thread:


Timbre matching a dubious feature?
http://www.avsforum.com/avs-vb/showt...8#post18467318


----------



## mtbdudex




> Quote:
> Originally Posted by *Electric_Haggis* /forum/post/20523746
> 
> 
> For the record, there's a great thread here that deals exclusively with dipoles, bipoles, quadpoles, etc...
> 
> http://www.avsforum.com/avs-vb/showthread.php?t=874378



Thx, 10 pages of detailed discussion, with references linked...started July-2007 and going strong thru Oct-2010.

I subscribed (my way of bookmark), this way I can read and absorb it.

(love my iPhone for these pure readings)


----------



## Dennis Erskine




> Quote:
> No matter, human brains don't interpret that as a timber shift, but as a directional shift.



Memories of SRS.










I don't want to leave the impression timbre isn't important; but, it is only one of "billions and billions" (to quote Carl Sagan) of combinations and permutations which need be considered when putting together a high performance (acoustic) space. When we consider the challenges of 6 to 8 seats in a small residential space, timbre matching surrounds will not necessarily be the biggest elephant in the room.


Larry, a doubling of the distance from the source will result (in round numbers) in a 6dB decrease in SPL. If you want to determine the SPL difference from surround speaker "A" between seats located at R1 and R2, here's a reasonable means to estimate that difference. SPL2 = SPL1 − 20 log10 (R2 / R1 ) With side surrounds you'd want the delta in SPL between the closest seat to the speaker to be not more than 3dBSPL higher than at the furthest seat from the speaker. You'd want to achieve the same with the rear surrounds and, of course, the front speakers as well. (Note ... you have to account for the radiation pattern of the speaker.) If you look at two rows of seating and a monopole speaker, from a timbre AND SPL perspective, you also need to recognize that one, if not both, rows will be off axis from the speaker. Since the distances (from side surrounds particularly) are much shorter than from the LCR's, listeners will be more off axis with respect to the side speakers than the front. More off axis equates to not only SPL differences but timbre as well.


Referring back to ITU specifications (and those configurations suggested by other sources), we generally see the ideal is that all speakers are equidistant from the (single) listening position. The impossibility of equidistant in most rooms was solved by receivers/pro-pros allowing you to set that distance in the speaker set-up menus. Or, did it really solve the problem? Not exactly. It solved a path, or phase, difference problem to a single seat. It certainly does not resolve a timbre difference in a room with multiple rows of multiple seats due to off axis response. How do you resolve that? Simple (maybe). You need to be careful of the off axis response characteristics of the speakers you select for *your* specific physical environment. The low hanging fruit may not be timbre.


----------



## Roger Dressler




> Quote:
> Originally Posted by *mbfleming* /forum/post/20524350
> 
> 
> It was Floyd E Toole that said that. See this thread:
> 
> 
> Timbre matching a dubious feature?
> http://www.avsforum.com/avs-vb/showt...8#post18467318



In your linked post we see the same dual perspective issue as afoot in this thread. I see no disagreement between Toole's and Paradigm's positions, because they are talking about different things, HRTFs vs speaker responses. In a room full of perfectly matched speaker responses, as measured with mics, the responses of the sounds _inside the ear canals_ will vary widely due to HRTFs. HRTFs do not require correcting.


----------



## Roger Dressler




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20524848
> 
> 
> I don't want to leave the impression timbre isn't important; but, it is only one of "billions and billions" (to quote Carl Sagan) of combinations and permutations which need be considered when putting together a high performance (acoustic) space. When we consider the challenges of 6 to 8 seats in a small residential space, timbre matching surrounds will not necessarily be the biggest elephant in the room.



Totally agree.



> Quote:
> Larry, a doubling of the distance from the source will result (in round numbers) in a 6dB decrease in SPL.



It will outside. But in a room, it varies. Usually less.


Just 5 min ago I pulled out my trusty RS meter and ran test noise in the center channel. At 6' and 12' (front edge of row 1 to rear edge of row 2). The difference was 2.5 dB. For the Left speaker is was 4 dB.


Worth checking if this is of interest in a particular room.


----------



## LarryChanin




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20523078
> 
> 
> Hi Dennis,
> 
> 
> With regard to timbre matching surrounds to the front speakers, a long time ago I thought recalled that you stated that due to the fact that surrounds are positioned to the sides or rear of the listener, even if they were identical to the mains, that they could never completely match in timbre. I have I expressed this correctly?





> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20524027
> 
> 
> Not Dennis, but one could say that HRTFs heavily influence the spectral balance for each speaker position. No matter, human brains don't interpret that as a timber shift, but as a directional shift.
> 
> 
> Anyway, the point I was making about timbre matching was aimed at what is coming out of the speakers. Identical speakers in a room that avoids degrading the responses is what I would qualify as timbre matched. And it is indeed achievable with monopoles (and judicious EQ and acoustic care) whereas with dipoles it simply is not.



Hi Roger,


Thanks for the response.


So, I guess if we are going to try determine the degree our surrounds "timbre match" our mains by means of listening tests, we should turn to face the surrounds as the test signal circulates around the room.


Then assuming that they are "matched" when listening to normal content facing forward we can expect our HRTF to help place the sound in the intended location, as the timbre is shifted.


Larry


----------



## LarryChanin




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20522688
> 
> 
> Once you have a small room with, say, two rows of seats and three to four seats in each row, monopoles can easily create a bigger problem than they solve. Other than timbre, you now have a situation where those on the ends of the rows are overwhelmed with that nearest side surround ... in other words, ears are soooo close to their respective side surround speaker, that speaker will over power the rears and opposite side speakers.





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20524848
> 
> 
> When we consider the challenges of 6 to 8 seats in a small residential space, timbre matching surrounds will not necessarily be the biggest elephant in the room.[...]
> 
> 
> With side surrounds you'd want the delta in SPL between the closest seat to the speaker to be not more than 3dBSPL higher than at the furthest seat from the speaker. You'd want to achieve the same with the rear surrounds and, of course, the front speakers as well. (Note ... you have to account for the radiation pattern of the speaker.) If you look at two rows of seating and a monopole speaker, from a timbre AND SPL perspective, you also need to recognize that one, if not both, rows will be off axis from the speaker. Since the distances (from side surrounds particularly) are much shorter than from the LCR's, listeners will be more off axis with respect to the side speakers than the front. More off axis equates to not only SPL differences but timbre as well.



Hi Dennis,


Thanks for your great insights.


With regard to attempting to maintain no more than a 3dBSPL difference between the closest and furthest seat from a side surround with two rows of seating, it would appear that placing a direct radiating surround between the two rows would offer an advantage.


With regard to attempting to maintain the listeners on axis to the side surrounds, a bipole surround speaker, that has two tweeters, one angled forward and one angled to the rear, if placed between two rows of seating can have a tweeter pointed toward *both* rows of seating simultaneously, something a monopole can't do.


Larry


----------



## Roger Dressler




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20525813
> 
> 
> With regard to attempting to maintain no more than a 3dBSPL difference between the closest and furthest seat from a side surround with two rows of seating, it would appear that placing a direct radiating surround between the two rows would offer an advantage.



Like any decision, it's a balance of tradeoffs. If a 5.1 system, putting them between the rows makes them pretty much "ITU" for the front row, and not so much for the rear. If a 7.1 system, not ideally placed for either row.


In my case, since I am the majority stakeholder and occupant, I chose to position the 7.1 speakers ideally for front row center. The surrounds being 90-deg from dead ahead.


Running a noise cal signal thru only the Ls speaker (direct radiator), here's what I measure at the 6 seats:


RowLCRFront+10.0-0.2Rear-1-0.50.0

I realize this is a crude test and does not tell us anything about responses. Would also be curious to see how these results would vary with a bipole and dipole.


----------



## Roger Dressler




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20525513
> 
> 
> So, I guess if we are going to try determine the degree our surrounds "timbre match" our mains by means of listening tests, we should turn to face the surrounds as the test signal circulates around the room.



You can, but do not necessarily need to do so. Since this is a subjective matter, how well they need to match and how to determine whether they do is up to you.


As with any aspect of sound quality, different people are sensitive to different aspects of sound. No way to say what is the singular formula for satisfying them all.


----------



## LarryChanin




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20527324
> 
> 
> Like any decision, it's a balance of tradeoffs. If a 5.1 system, putting them between the rows makes them pretty much "ITU" for the front row, and not so much for the rear. If a 7.1 system, not ideally placed for either row.
> 
> 
> In my case, since I am the majority stakeholder and occupant, I chose to position the 7.1 speakers ideally for front row center. The surrounds being 90-deg from dead ahead.



Hi Roger,


According to the attached ITU diagrams (excerpted from Toole) placing a surround between the two rows would comply with a 7.1 system for both rows.


A 90 degree placement of the surrounds would not comply with a 5.1 system. (I know your configuration is 7.1, so it also complies.)


Larry


----------



## Roger Dressler




> Quote:
> Originally Posted by *LarryChanin* /forum/post/20527554
> 
> 
> Hi Roger,
> 
> 
> According to the attached ITU diagrams (excerpted from Toole) placing a surround between the two rows would comply with a 7.1 system for both rows.
> 
> 
> A 90 degree placement of the surrounds would not comply with a 5.1 system. (I know your configuration is 7.1, so it also complies.)



The ITU 7.1 diagram can allow a number of "compliant" setups that would be far from ideal. I think they wisely decided to avoid "going there."


----------



## localhost127

thanks for the insight on the topic, everyone.


----------



## A9X-308

Here is a rough early Sketchup of my apartment living room/ theatre showing approx speaker positions and intended layout.











Apartment is 2 story, 150mm concrete slab floor and ceiling, double brick rendered walls. Room is 6.2 x 3.2 x x2.6m (lwh) and the floor is tiled. The 'front wall' shows the outline of a 2.4m wide sliding glass door to a veranda but does not show the retractable screen there, nor does the back wall show the projector mount on the wall above the couch.


Main speakers are Unity designs so are 60* directivity from 300hz up. These and the surrounds look a bit different now as this is an old sketch but it will give an idea. No subs shown as I haven't decided what to do in that regard yet; that's another discussion.


I live alone, so the decor can be whatever I like. Listening position is the chair location, and when I have company, I slide the couch forward, so I'm only interested in one position/row.


Absorptive panels are easy to make, as are QRD and PRD, if a bit time consuming. I have a friend with a slick method to make either.


Please ignore issues re electronics, neighbours etc as I have those solved.


I have my ideas already, but would like to see what others with more experience suggest first. I have a great mic and measurement tools and am willing to experiment.


----------



## localhost127




> Quote:
> Originally Posted by *A9X-308* /forum/post/20564643
> 
> 
> I have my ideas already, but would like to see what others with more experience suggest first. I have a great mic and measurement tools and am willing to experiment.



1st step is measurements. 2nd step is moving speaker + listening position around to get the best possible starting point. it's a smaller room so you'll need as much bass trapping as possible. especially with the concrete/brick boundaries.



> Quote:
> are easy to make, as are QRD and PRD, if a bit time consuming. I have a friend with a slick method to make either.



that easy for him to make, eh? how much does he charge


----------



## alittletank

Most of the talk in this thread has bounded right over my head. Is there an acoustics for dummies reference someone can point me to? I would really like to educate myself but my starting knowledge point is light years behind most of you.


Thanks

Allen


----------



## localhost127




> Quote:
> Originally Posted by *alittletank* /forum/post/20565332
> 
> 
> Most of the talk in this thread has bounded right over my head. Is there an acoustics for dummies reference someone can point me to? I would really like to educate myself but my starting knowledge point is light years behind most of you.
> 
> 
> Thanks
> 
> Allen


 http://www.ethanwiner.com/acoustics.html 

http://www.customaudiodesigns.co.uk/...s/rpgpaper.htm 


vocabulary may seem foreign at first. re-read the articles over and over over the course of a few days and it'll begin to sink in.


----------



## Roger Dressler

Quote:

Originally Posted by *A9X-308* 
Apartment is 2 story, 150mm concrete slab floor and ceiling, double brick rendered walls.


No subs shown as I haven't decided what to do in that regard yet; that's another discussion.
Too soon to start? Sorry.










I'd anticipate a shocking lack of bass in the MLP and a shocking abundance on the sofa. No practical amount of bass absorbers will solve it, so you'll need some form of multi-sub + tuning solution to make a dent. Even then, I'd pull the sofa off the back wall a couple feet if at all possible, unless it's just for occasional, casual use.


My guess is that a pair of subs along the side walls, parked just forward of the Ls/Rs speakers, might be a good place to start.


----------



## A9X-308

Quote:

Originally Posted by *Roger Dressler* 
Too soon to start? Sorry.








No, just that I had planned to buy 4 or so Tempest II drivers, but no more are being made, and none are in stock down here, so I'm still mulling the alternatives. I have lots of amps, EA and xovers, just need to suss what drivers to use when I have the readies in my pocket. There are some new/re-issued designs forthcoming, and I'll wait a while to see what I can actually buy (in Australia) then.

Quote:

Originally Posted by *Roger Dressler* 
I'd anticipate a shocking lack of bass in the MLP and a shocking abundance on the sofa. No practical amount of bass absorbers will solve it, so you'll need some form of multi-sub + tuning solution to make a dent. Even then, I'd pull the sofa off the back wall a couple feet if at all possible, unless it's just for occasional, casual use.
Couch is not a listening position, except if I pull it forward to where the chair is for 2 person viewing. I have 3 of the Ikea chairs I can use as well, and the couch is more for when I have non viewing social company.

Quote:

Originally Posted by *Roger Dressler* 
My guess is that a pair of subs along the side walls, parked just forward of the Ls/Rs speakers, might be a good place to start.
I haven't finished the other speakers yet, but have a couple of modest 12" sealed subs, that will do for low level testing once I start. My first thought configuration was one each mid sidewall as you suggest, as well as maybe w/4 adjacent to the mains on the front wall. It doesn't matter if they block the door most of the time as I can put them on castors to move when needed. The above based upon some of the Welti paper positions.


I was most hoping for acoustic suggestions for room treatment.


My initial thoughts:

- chunk type corner absorbers front corners and the one rear.

- 4" OC703 side walls adjacent to the mains. I know the incident angles are wrong, but should reduce diffractive effects from the horn mouth and provide some absorption to the room.

- similar 45* angled panels wall/ceiling side, rear and above screen front.

- footrest shown is just a visual guide. I have one day bed size with a 6" thick futon (all cotton) to minimise floor bounce.


- 1D QRD on the side walls between the mains and sides.

- 2D PRD covering rear wall above couch at least as wide as the couch.


Comments?


----------



## localhost127

Quote:

Originally Posted by *Roger Dressler* 
I'd anticipate a shocking lack of bass in the MLP and a shocking abundance on the sofa. No practical amount of bass absorbers will solve it, so you'll need some form of multi-sub + tuning solution to make a dent.
bass trapping may not solve his response issues at the MLP, but they certainly will help with the modal ringing (LF decay times) - which will be very apparent in such a small space.


----------



## localhost127

Quote:

Originally Posted by *A9X-308* 
I was most hoping for acoustic suggestions for room treatment.


My initial thoughts:

- chunk type corner absorbers front corners and the one rear.

- 4" OC703 side walls adjacent to the mains. I know the incident angles are wrong, but should reduce diffractive effects from the horn mouth and provide some absorption to the room.

- similar 45* angled panels wall/ceiling side, rear and above screen front.

- footrest shown is just a visual guide. I have one day bed size with a 6" thick futon (all cotton) to minimise floor bounce.


- 1D QRD on the side walls between the mains and sides.

- 2D PRD covering rear wall above couch at least as wide as the couch.


Comments?
since the room is relatively small, you'll want as much porous bass trapping as possible (or measure and install pressure-based traps if you are up to the challenge to design & construct). modal ringing will definitely be an issue. since you do not have much real estate (especially with so many speakers in the room), it would be better to do superchunks of higher density (gas-flow resistivity) material such as OC705. normally, low GFR material like super-deep corner traps loosely filled with cheap, pink fluffy insulation would be extremely effective, but in this case you will likely want to do shallower corner chunks with denser material. can you squeeze the 34" faced superchunks in all corners? are you able to do the same for the wall/ceiling boundaries as well? any and all corners.


id also recommend 4-6" OC703 broadband absorber (spaced off the wall a few inches if possible) on the rear wall directly behind the listening position.


as for specular energy control - with so much sonic energy in such a small room, the first-order reflections will definitely need to be attenuated. the front right speaker first-order reflection off the left wall is going to confuse imaging. especially masking the middle-left surround signal. can you attack these reflection points with 4" OC703? (+ any air gap you can afford)? you'll have so much energy in the room (from so many speakers), i doubt you'll have an issue of making the room overly dead before you solve your modal issues. i would experiment first with lots of broadband absorption (for specular reflections - at first reflection points for each speaker) before applying any diffusion. don't forget the ceiling!


if you do decided to add diffusion,

im going to throw this out there and see what the pro's recommend, but it'd suggest doing all 2D PRDs simply because you have so much energy (many speakers) in such a small space, it may be more beneficial to diffuse the energy in 2dimensions to better break up the specular reflections (lower gain return), vs 1D where you may still have too much return energy from diffuse-field. the 2D diffusers will act like very complex absorbers. the problem, is your Envelope Time Curve (ETC) will be quite a mess with so many speakers and such short reflection paths. you will likely have to do lots of experimentation to see what sounds best to you. but start with the ETC one speaker at a time and try and attenuate all reflections within 20ms of the original signal. remember, if you are adding diffusion you will want to sit at least 3 wavelengths of the design frequency away from the diffuser (if possible).


just my $0.02. looking forward to seeing how it goes!


----------



## localhost127

another great discussion:

http://www.gearslutz.com/board/studi...ffraction.html


----------



## localhost127

new porous absorber calculator:

http://www.stanleyhallstudios.co.uk/pacalc/


----------



## monstosity12

Can someone help me decide what would be best in my situation... Im no expert in sound absorption.



I will be making some corner bass traps [studiotips superchunks]


Should I get Mineral wool 1280 [8 pcf.] @ insulationworld.

or should I get roxual rockboard 60 [6 pcf] @ atsacoustics.


Or any other place that is recommended that is cheaper, this would be great.


The rockboard 60 would save around $70...So I am very curoius.


----------



## localhost127

Quote:

Originally Posted by *monstosity12* 
Can someone help me decide what would be best in my situation... Im no expert in sound absorption.



I will be making some corner bass traps [studiotips superchunks]


Should I get Mineral wool 1280 [8 pcf.] @ insulationworld.

or should I get roxual rockboard 60 [6 pcf] @ atsacoustics.


Or any other place that is recommended that is cheaper, this would be great.


The rockboard 60 would save around $70...So I am very curoius.
how much real estate can you afford to give up?

as you make thicker and thicker porous bass traps for LF/modal issues (which will become more effective the further the material is placed from the boundary) - you will want to use a material with lower gas-flow-resistivity. *if cost is an issue*, but real estate not, you can build corner traps with loosely filled cheap pink fluffy (attic) insulation. if made very deep, they will become more effective than standard corner traps or superchunks with the denser material you listed above. and best of all, you could pick them up locally vs having to incur shipping costs like on your two options above. cheaper, and more effective - as long as you can give up some extra space for thicker traps.


----------



## FOH

Quote:

Originally Posted by *localhost127* 
as you make thicker and thicker porous bass traps for LF/modal issues (which will become more effective the further the material is placed from the boundary) - you will want to use a material with lower gas-flow-resistivity.


........ they will become more effective than standard corner traps or superchunks with the denser material you listed above.
I've seen you post this a few times, and this is quite interesting.


Could you elaborate, or link to work illustrating this increase in effectiveness. How much more effective would you say, in percentage, would be the pink fluffy loose stuff over 703 etc? At what size(depth?) would one begin to consider a change of density wrt LF trap material?


Thanks


----------



## localhost127

Quote:

Originally Posted by *FOH* 
I've seen you post this a few times, and this is quite interesting.


Could you elaborate, or link to work illustrating this increase in effectiveness. How much more effective would you say, in percentage, would be the pink fluffy loose stuff over 703 etc? At what size(depth?) would one begin to consider a change of density wrt LF trap material?


Thanks
play around w/ the porous absorber calculator - very thick traps (16"+).


too thick of dense (high GFR) porous material will start to reflect and be less effective (all absorbers will have a reflective component) - hence the thicker the trap the lower the GFR of the material.


save the expensive OC703 for broadband panels to combat specular reflections. with the caveat that one has the additional real estate to give up in the corners.


e.g, straddle 16"+ thick traps of loosely filled pink fluffy insulation in the corners (and stuff the air gap). chicken wire could be used (just need to make sure the stacks of loose fluffy don't compress at the bottom due to gravity).


would also be great for *massively* thick rear wall trap (behind the listening position) - and then one could build diffusers on gobos or stands to place in front of the rear wall trap.


----------



## jfeva0049

looking for advice, i want to build bass traps in the corners but dont have much room in the corners to work with. would i even benefit from making a 12" super chunk or is that to small to even do anything for bass?


----------



## localhost127




> Quote:
> Originally Posted by *jfeva0049* /forum/post/20597843
> 
> 
> looking for advice, i want to build bass traps in the corners but dont have much room in the corners to work with. would i even benefit from making a 12" super chunk or is that to small to even do anything for bass?



if you are resource limited, it is always better to cover more sq. area than using more material in a single corner (regarding porous bass traps). you need large amount of sq area to be effective - but the amount of material in each corner still needs to be sufficient to be effective. coverage is key, as is placement of the treatment at areas of high effectiveness.


could you fit a 24"x24" x 34"(face) triangle into each of your corners? what about ceiling-wall corners?


----------



## jfeva0049

found a way to add pic's of my room. need help on treating my room, any advice helps out a bunch. room specs are 18'x14'x8'. Attachment 215599 

Attachment 215600 

Attachment 215601 

Attachment 215602


----------



## jfeva0049




> Quote:
> Originally Posted by *localhost127* /forum/post/20597930
> 
> 
> could you fit a 24"x24" x 34"(face) triangle into each of your corners? what about ceiling-wall corners?



as you can see from the pic's i just posted, if i put to large of a corner bass trap i will not have any room for flat panels on the back wall. im not sure whats best for the back wall; small bass trap and flat panel or just bass trap or just thicker flat panel??


----------



## localhost127

can you source OC703 locally in your area?

is that a window behind the curtains? (is that couch in front of the curtains the main listening position)? can you space the couch a few feet away from the real wall/window?


----------



## jfeva0049




> Quote:
> Originally Posted by *localhost127* /forum/post/20599095
> 
> 
> can you source OC703 locally in your area?
> 
> is that a window behind the curtains? (is that couch in front of the curtains the main listening position)? can you space the couch a few feet away from the real wall/window?



yes i can get 703


yes it is a large window and it is the main listening position.


and i could bring it out maybe a foot or so but dont really want it out more then that really.


btw thanks for your input.


----------



## monstosity12




> Quote:
> Originally Posted by *localhost127* /forum/post/20596762
> 
> 
> how much real estate can you afford to give up?
> 
> as you make thicker and thicker porous bass traps for LF/modal issues (which will become more effective the further the material is placed from the boundary) - you will want to use a material with lower gas-flow-resistivity. *if cost is an issue*, but real estate not, you can build corner traps with loosely filled cheap pink fluffy (attic) insulation. if made very deep, they will become more effective than standard corner traps or superchunks with the denser material you listed above. and best of all, you could pick them up locally vs having to incur shipping costs like on your two options above. cheaper, and more effective - as long as you can give up some extra space for thicker traps.



Thanks localhost127.


Upon you wisdom, I will be making the 34" faced superchunks in my corners. So I have since ordered the 2.5 pcf mineral wool instead, as you said, thicker you go, the lower density mineral wool you should use. *Is the 2.5 pcf mineral wool to dense for a 34" faced superchunk bass trap.*

Using Roxul acoustical fire batt. Much cheaper.


----------



## localhost127




> Quote:
> Originally Posted by *monstosity12* /forum/post/20601191
> 
> 
> Thanks localhost127.
> 
> 
> Upon you wisdom, I will be making the 34" faced superchunks in my corners. So I have since ordered the 2.5 pcf mineral wool instead, as you said, thicker you go, the lower density mineral wool you should use. *Is the 2.5 pcf mineral wool to dense for a 34" faced superchunk bass trap.*
> 
> Using Roxul acoustical fire batt. Much cheaper.



go lower density (GFR) material once you reach *very* thick traps ... for 34" superchunk, you can use > 2.5pcf mineral wall (oc703 is 3pcf and oc705 is 6pcf if i recall correctly). 2.5 pcf is not too dense and you can do denser for the 34" superchunk. what-ever is most cost effective if that is a requirement.


you could also install a horizontal (48"wide x 24" height broadband panel) on a stand(gobo) that you could always slide into position in front of the window when doing critical listening or watching a movie.


ideally, you would want to take measurements of the room beforehand and adjust speaker + listening placement to find the best 'starting point' - and then use treatments to tame the specific, measured issues within your room (and then measure again once treatments are in place to verify they are in areas of high effectiveness and that they have tamed the original problem they were procured for).


the more corners (sq area) you hit with effective corner trapping for modal issues, the better.


----------



## osofast240sx

Hey guys I'm looking for carpet for my co op. I'm on the 6th floor need to reduce noise. Need a thick carpet and something thick to go underneath the carpet. Thanks


----------



## nathan_h




> Quote:
> Originally Posted by *osofast240sx* /forum/post/0
> 
> 
> Hey guys I'm looking for carpet for my co op. I'm on the 6th floor need to reduce noise. Need a thick carpet and something thick to go underneath the carpet. Thanks



Are you trying to stop bass thump from annoying the neighbors? Carpet wont do it but will likely make the room itself sound better to you, which is what this thread is about.


One possibility is an auralex gramma pad for your sub.


But I'm only guessing at what you are trying to solve.


----------



## osofast240sx




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> 
> Are you trying to stop bass thump from annoying the neighbors? Carpet wont do it but will likely make the room itself sound better to you, which is what this thread is about.
> 
> 
> One possibility is an auralex gramma pad for your sub.
> 
> 
> But I'm only guessing at what you are trying to solve.



Sound is my number one priority but I'm also looking into an acoustic underlay to do both.


----------



## nathan_h




> Quote:
> Originally Posted by *osofast240sx* /forum/post/0
> 
> 
> 
> Sound is my number one priority but I'm also looking into an acoustic underlay to do both.



Sorry, your post is not clear.


What kind of noise is bothering the neighbors?


There may or may not be a partial solution available to you for that, without some real construction. But if you post mote info, the folks here will likely have some more questions and answers. For example, if they are complaining about bass thump, the carpet pad won't do much at all. But an isolation platform for the sub mihgt help a little.



-------


To make the room sound good, inside the room, start here:

http://www.realtraps.com/art_basics.htm


----------



## monstosity12

Thanks everyone for your help with my build of the superchunks 34" faced. Built with 2.5 pcf. It feels like they compress quite a bit with a 7 foot tall column of mineral wall, but since its only 2.5 pcf im sure this wont hurt with the gas flow resitance. right? I used ATSacoustics microssuede acoustic fabric, seems like a very tight weave as I really cant feel any air when I blow on it.


My echo when I clap my hands has basically disappated. 1 more corner to go.


*Question*: Since my corners are done, are there any other places I should place a 6" flat bass trap? Im thinking right in the middle of the back wall...Sound good? What pcf mineral wool should this be, since this will only be 6" deep [and 24" x 48"]?



P.s> its amazing how superchunks, aka bass traps in general, make subwoofers sound so clean and smooth, but tighter.


----------



## mtbdudex




> Quote:
> Originally Posted by *monstosity12* /forum/post/20614505
> 
> 
> Thanks everyone for your help with my build of the superchunks 34" faced. Built with 2.5 pcf. It feels like they compress quite a bit with a 7 foot tall column of mineral wall, but since its only 2.5 pcf im sure this wont hurt with the gas flow resitance. right? I used ATSacoustics microssuede acoustic fabric, seems like a very tight weave as I really cant feel any air when I blow on it.
> 
> 
> My echo when I clap my hands has basically disappated. 1 more corner to go.
> 
> 
> *Question*: Since my corners are done, are there any other places I should place a 6" flat bass trap? Im thinking right in the middle of the back wall...Sound good? What pcf mineral wool should this be, since this will only be 6" deep [and 24" x 48"]?
> 
> 
> 
> P.s> its amazing how superchunks, aka bass traps in general, make subwoofers sound so clean and smooth, but tighter.



monstosity12 - did you place something to block mid-hi freq on the front or leave them open?

I have other treatments in my room so did not want it to sound too "dead", not sure what other treatments you have, but in general people cover the front, since they are broadband "bass traps" not intended to be mid/hi freq absorbers also.

Pict shows me using kraft paper to block mid-hi freq.


----------



## monstosity12




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20615137
> 
> 
> monstosity12 - did you place something to block mid-hi freq on the front or leave them open?
> 
> I have other treatments in my room so did not want it to sound too "dead", not sure what other treatments you have, but in general people cover the front, since they are broadband "bass traps" not intended to be mid/hi freq absorbers also.
> 
> Pict shows me using kraft paper to block mid-hi freq.



Thanks mtbdudex -


Yeah, I bought atsacoustics microsuede acoustic black fabric and used this. So you think I should use something that blocks the higher frequecies? This would be a bummer as the fabric for 5 yard was $50.00, but nonetheless could have saved me $50.00


As far as other treatments, I have none.


----------



## mtbdudex




> Quote:
> Originally Posted by *monstosity12* /forum/post/0
> 
> 
> 
> Thanks mtbdudex -
> 
> 
> Yeah, I bought atsacoustics microsuede acoustic black fabric and used this. So you think I should use something that blocks the higher frequecies? This would be a bummer as the fabric for 5 yard was $50.00, but nonetheless could have saved me $50.00
> 
> 
> As far as other treatments, I have none.



You put the kraft paper under your fabric, it blocks short wavelength but long wavelength will bend around it.

Since you don't plan on other treatments , ie, side wall / ceiling mid/hi freq absorbers for RFZ you should be ok as is.


----------



## A9X-308

I had my mid year exams all last week (very postgrad Rodney Dangerfield), so I didn't have time to think bout this a lot until now.



> Quote:
> Originally Posted by *localhost127* /forum/post/20565137
> 
> 
> 1st step is measurements. 2nd step is moving speaker + listening position around to get the best possible starting point. it's a smaller room so you'll need as much bass trapping as possible. especially with the concrete/brick boundaries.



Mains can't move much, but I'm not seeing much reason why I should. I have directivity at +/- 30° in both planes from 300hz up, floor bounce will be mitigated (averaged) by the MTM 15's and the 6" thick cotton futon ottoman and any boundary reinforcement at LF that's troublesome from the EQ in the active xovers.


I agree, measure first, but I'm looking for suggestions to reduce muck around time once I do.



> Quote:
> Originally Posted by *localhost127* /forum/post/20565137
> 
> 
> that easy for him to make, eh? how much does he charge



I've seen you at gearslutz - look for terry j's threads - it's all in there



> Quote:
> Originally Posted by *localhost127* /forum/post/20566474
> 
> 
> bass trapping may not solve his response issues at the MLP, but they certainly will help with the modal ringing (LF decay times) - which will be very apparent in such a small space.



This one has me a little perplexed. I can see easily why there would be lateral and vertical reflections to set up standing waves, but the front wall behind the mains is all glass. Combined with the large openings at the sides at the other end, I can see how a 1/2 wave resonance might be set up but there should be enough leakage from the openings to reduce that a lot. Measurements will see I know. These will come soon as I've ordered some more ICs to make the new preamp for the mic after the last one was broken on loan. Not a problem as this one will be quieter anyway.



> Quote:
> Originally Posted by *localhost127* /forum/post/20566500
> 
> 
> since the room is relatively small, you'll want as much porous bass trapping as possible (or measure and install pressure-based traps if you are up to the challenge to design & construct). modal ringing will definitely be an issue. since you do not have much real estate (especially with so many speakers in the room), it would be better to do superchunks of higher density (gas-flow resistivity) material such as OC705. normally, low GFR material like super-deep corner traps loosely filled with cheap, pink fluffy insulation would be extremely effective, but in this case you will likely want to do shallower corner chunks with denser material. can you squeeze the 34" faced superchunks in all corners? are you able to do the same for the wall/ceiling boundaries as well? any and all corners.



I can make it that large in the rear corner but the fronts could only be about 60cm / 26" on the diagonal. Wall/ceiling boundary can be made the same way, with a frame and low density glass held up by French cleats - this was my original plan.



> Quote:
> Originally Posted by *localhost127* /forum/post/20566500
> 
> 
> id also recommend 4-6" OC703 broadband absorber (spaced off the wall a few inches if possible) on the rear wall directly behind the listening position.



Wahy not a QRD/PRD? I have been playing with QRDude since Bill first put it up and have been crawling my way through D'Antonio's book.



> Quote:
> Originally Posted by *localhost127* /forum/post/20566500
> 
> 
> as for specular energy control - with so much sonic energy in such a small room, the first-order reflections will definitely need to be attenuated. the front right speaker first-order reflection off the left wall is going to confuse imaging. especially masking the middle-left surround signal. can you attack these reflection points with 4" OC703? (+ any air gap you can afford)? you'll have so much energy in the room (from so many speakers), i doubt you'll have an issue of making the room overly dead before you solve your modal issues. i would experiment first with lots of broadband absorption (for specular reflections - at first reflection points for each speaker) before applying any diffusion. don't forget the ceiling!



Good point re the first reflection points on the opposite walls for the mains. When I drew the angles out in Sketchup it became obvious. I'll look at those too.


As for the ceiling, that's difficult as it has a patterned plaster finish I am loathe to drill into as I wouldn't be able to patch it cleanly when I move out later back to my house. I have thought of some wall mounted truss frame to achieve this, which is easily done, but it will be last on the list.



> Quote:
> Originally Posted by *localhost127* /forum/post/20566500
> 
> 
> if you do decided to add diffusion,
> 
> im going to throw this out there and see what the pro's recommend, but it'd suggest doing all 2D PRDs simply because you have so much energy (many speakers) in such a small space, it may be more beneficial to diffuse the energy in 2dimensions to better break up the specular reflections (lower gain return), vs 1D where you may still have too much return energy from diffuse-field. the 2D diffusers will act like very complex absorbers. the problem, is your Envelope Time Curve (ETC) will be quite a mess with so many speakers and such short reflection paths. you will likely have to do lots of experimentation to see what sounds best to you. but start with the ETC one speaker at a time and try and attenuate all reflections within 20ms of the original signal. remember, if you are adding diffusion you will want to sit at least 3 wavelengths of the design frequency away from the diffuser (if possible).
> 
> 
> just my $0.02. looking forward to seeing how it goes!



I've looked at a number of diffuser designs and the original plan was for some diffusion in the centre 2/3 above the couch in the pic, and some absorption at the sides.


I've also been reading a lot of other sites, and Ethan's Manhattan Apartment is a very good visualisation of my ideas. My room is a bit wider and longer is all.


If from the above I'm heading in the wrong direction, people please speak up. I'm very technical and can work things out, but what I've sort of been hoping for is some 'if that was my room, I would do..., and ....'


WRT to subs I will soon have 8 12" drivers to make into 4 PP manifold loaded enclosures as a start. I might add more later, depending on how the neighbours react to those. I have a DCX (EQ/xover) just for them and lots of amps.


----------



## localhost127




> Quote:
> Originally Posted by *A9X-308* /forum/post/20621684
> 
> 
> Mains can't move much, but I'm not seeing much reason why I should. I have directivity at +/- 30° in both planes from 300hz up, floor bounce will be mitigated (averaged) by the MTM 15's and the 6" thick cotton futon ottoman and any boundary reinforcement at LF that's troublesome from the EQ in the active xovers.



the placement was in regards to modal issues (along with SBIR combination from the front boundaries in the room). 300hz and up shouldnt be a problem, but placement is key for the low end.



> Quote:
> Originally Posted by *A9X-308* /forum/post/20621684
> 
> 
> This one has me a little perplexed. I can see easily why there would be lateral and vertical reflections to set up standing waves, but the front wall behind the mains is all glass. Combined with the large openings at the sides at the other end, I can see how a 1/2 wave resonance might be set up but there should be enough leakage from the openings to reduce that a lot. Measurements will see I know. .



yeah -- too complex to guess. measurements will be worthwhile.



> Quote:
> Originally Posted by *A9X-308* /forum/post/20621684
> 
> 
> Wahy not a QRD/PRD? I have been playing with QRDude since Bill first put it up and have been crawling my way through D'Antonio's book.



regarding how close you were sitting to the rear wall. if you can space yourself away, then try diffusion and see how it works. absorption is quick and cheap - could always place mid/HF diffusion in front of the absorber.



> Quote:
> Originally Posted by *A9X-308* /forum/post/20621684
> 
> 
> Good point re the first reflection points on the opposite walls for the mains. When I drew the angles out in Sketchup it became obvious. I'll look at those too.
> 
> 
> As for the ceiling, that's difficult as it has a patterned plaster finish I am loathe to drill into as I wouldn't be able to patch it cleanly when I move out later back to my house. I have thought of some wall mounted truss frame to achieve this, which is easily done, but it will be last on the list.



definitely focus on the lateral (side-wall) reflection points first.



> Quote:
> Originally Posted by *A9X-308* /forum/post/20621684
> 
> 
> If from the above I'm heading in the wrong direction, people please speak up. I'm very technical and can work things out, but what I've sort of been hoping for is some 'if that was my room, I would do..., and ....'



sounds like a great start. please keep us posted with your findings and conclusions!


----------



## A9X-308




> Quote:
> Originally Posted by *localhost127* /forum/post/20622672
> 
> 
> but placement is key for the low end.



I have gobs of EQ capability in the digital xovers.


> Quote:
> Originally Posted by *localhost127* /forum/post/20622672
> 
> 
> regarding how close you were sitting to the rear wall. if you can space yourself away, then try diffusion and see how it works. absorption is quick and cheap - could always place mid/HF diffusion in front of the absorber.



Main listening position is not the couch, but the chair, a good 2m or more from the back wall. I live on my own, so the chair is most comfy then, and when I have company, I can easily slide the couch forward to that position.


----------



## erkq




> Quote:
> Originally Posted by *A9X-308* /forum/post/20622764
> 
> 
> I have gobs of EQ capability in the digital xovers.



"Gobs" of EQ is not good. If you truly have to use "gobs", you are trying to fix a big problem by overpowering it and the results will reflect that. Get the best you can with placement and then use your EQ.


----------



## CruelInventions

"gobs of EQ capability", with "*capability*" being the key word you overlooked. Meaning, he has great potential flexibility to address whatever specific issue or issues should arise, given the breadth and quality of EQ features at his disposal. Not that he has used gobs of EQ to address some existing problem.


----------



## localhost127




> Quote:
> Originally Posted by *CruelInventions* /forum/post/20623277
> 
> 
> "gobs of EQ capability", with "*capability*" being the key word you overlooked. Meaning, he has great potential flexibility to address whatever specific issue or issues should arise, given the breadth and quality of EQ features at his disposal. Not that he has used gobs of EQ to address some existing problem.



how does one EQ out of infinite nulls?

how does EQ remove modal ringing (LF decay) from within the room?


----------



## erkq




> Quote:
> Originally Posted by *CruelInventions* /forum/post/20623277
> 
> 
> "gobs of EQ capability", with "*capability*" being the key word you overlooked.



No, I didn't "overlook" it. Localhost has a good response.


----------



## CruelInventions

Quote:

Originally Posted by *localhost127* 
how does one EQ out of infinite nulls?

how does EQ remove modal ringing (LF decay) from within the room?
I didn't mean to imply that within the "gobs of EQ capability" there will necessarily be solutions to resolve or help minimize every type of problem, per se. My only point really was that erkg misunderstood the meaning of the comment being made by A9X-308. His misunderstanding of that comment still stands, i.e., taking "gobs" as meaning "to be used all at once". That's not what A9X-308 said.


Anyway, I'm sure A9X-308 can tell us what he meant better than anyone else can, myself included.


----------



## A9X-308

Pretty much what CI said. I have the _capability_ to use EQ as needed to correct what I can. I would never try to EQ out nulls, nor modal issues (but I have already covered that so strawman). The speakers were intended for near corner placement from the start and I knew that the general LF gain from moving from 1/2 space models to something closer to 1/4 space would be needed once in situ and measured.


----------



## GPBURNS

Interesting thread here and treatments make fantastic

improvement if done properly

But there is one thing that I am always puzzled by

In searching the internet on acoustic treatments

There are so many threads/discussion/project etc

But rarely do you ever see any measurements

Especially before /after graphs on response and ringing/bass decay etc

Is everybody just throwing darts at the frequency's that need help?


----------



## Brad Horstkotte

Check the Home Theater Shack's REW / acoustics forum, there are quite a few before, during afters there - here as well, but due to organization, not as easy to find them. Check Ethan Winer's site for his before and afters as well.


----------



## GPBURNS

Thanks - I have seen those links but just talking more in general

you just do not see a lot of it

maybe we will see more now that easy to use products like Omnimic

are becoming available


----------



## localhost127

 http://www.gearslutz.com/board/studi...ing-acoustics/ 
http://www.gearslutz.com/board/bass-...nels-foam-etc/ 


no one really responds in the GS threads unless measurements are provided to identify specific issues that need to be addressed.

not much of any work gets done there *without* measurements...



> Quote:
> Originally Posted by *GPBURNS* /forum/post/20701947
> 
> 
> Is everybody just throwing darts at the frequency’s that need help?



porous absorption is broadband, and as such the only relevance to a specific 'frequency' is how deep the porous bass trap is (thus determining how low in frequency absorption will take place; or how effective the absorption will be at lower frequencies). above that, it's more of a 'catch-all'...*but you really cannot have too much LF broadband absorption in small acoustical spaces.*


measurements are also used as the traps are moved into different areas of the room, or spaced further from the boundary, and thus, areas of highest effectiveness are found (via measurements).


now, for pressure-based traps, the specific (measured) trouble frequency is imperative to know, as that is what you're designing your bass trap center frequency to.


peaks or nulls in the LF region can also be caused by SBIR or LBIR (not just modal issues) - so there is also a requirement for moving the speaker position (all 3 axis) as well as the listening position. measurements are taken here to find the best possible response given the physical layout of these placements.




> Quote:
> Originally Posted by *GPBURNS* /forum/post/20701947
> 
> 
> But rarely do you ever see any measurements



quote from a GS thread:



> Quote:
> I'd just like to remark that it's great that we've reached a point where testing results, either from REW, FM, or whatever, have become common and almost expected. When I joined here a bit over a year ago testing was rare.





> Quote:
> Originally Posted by *SAC* /forum/post/6475837
> 
> 
> The norm was "show us the frequency response and the RT60 results..."
> 
> And anyone who suggested otherwise was a heretic...
> 
> 
> Damned heretics...


----------



## localhost127

GPBURNS,
http://www.gearslutz.com/board/bass-...ml#post6098894 
http://www.gearslutz.com/board/studi...lems-help.html 


some delightful threads on the subject:
http://www.gearslutz.com/board/bass-...absorbers.html 
http://www.gearslutz.com/board/studi...q-4-avare.html 
http://www.gearslutz.com/board/studi...4207-sbir.html


----------



## GPBURNS




> Quote:
> Originally Posted by *localhost127* /forum/post/20703456
> 
> 
> GPBURNS,
> http://www.gearslutz.com/board/bass-...ml#post6098894
> http://www.gearslutz.com/board/studi...lems-help.html
> 
> 
> some delightful threads on the subject:
> http://www.gearslutz.com/board/bass-...absorbers.html
> http://www.gearslutz.com/board/studi...q-4-avare.html
> http://www.gearslutz.com/board/studi...4207-sbir.html



thxs


----------



## pepar

yes thx indeed.


----------



## mtbdudex

Gpburns, where are you on the acoustical journey?


----------



## GPBURNS




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20703966
> 
> 
> Gpburns, where are you on the acoustical journey?



Long way in - but always trying to learn stuff

Still remember being introduced to the wonderful world of room modes

after buying my first sub - a Veloydne uld-12 back in the day


----------



## mtbdudex




> Quote:
> Originally Posted by *GPBURNS* /forum/post/20704868
> 
> 
> Long way in - but always trying to learn stuff
> 
> Still remember being introduced to the wonderful world of room modes
> 
> after buying my first sub - a Veloydne uld-12 back in the day



understood - its a fun thing....acoustics.

How "done" is your listening environment?


For some reason it sure brings out the passion in people discussing and debating....


Frankly I've read the 2 basic "books"; master handbook by Everest and sound reproduction by Toole, realizing there are more books out there but also being practical, I'm not getting a BS in acoustic science either.

(ha, I finished college with my MSME in 1988....)

Plus, the white papers/BBC studies/etc.


Also got all the measurement equipment, and finally have my HT room lets say 90% dialed.

The 10% remaining is that elusive quest for the pinnacle in acoustics.

for most people unless your are a HT designer/builder we only do this once or twice in our lifetime, takes so much time/study.


I'm still learning, reading posts in various forums, and gaining more intuitive feel for objective measurements correlated to subjective listening.

It takes time, and my wife grants me as a side hobby to the HT.


besides here the Audio theory, Setup and Chat forum is where a lot of acoustic discussion is held, plus the audyssey thread, the DIY speakers forum, etc.

Seems to pop up in various forums here on avs....which is a good thing different viewpoints give you more insight.


I've babbled enough, peace!


----------



## Digital_Chris

Hey guys! Soon I will be finishing my theater, but in the mean time, I wanted to get a good idea of what to do for room treatments. I have a couple of concerns though...


I did read a bit of this thread already but there are so many different opinions and people with different room sizes and acoustical goals that it was hard to gather the right information for my small room. Here are my thoughts...


My main concern comes from my room being so small (18' x 10' x 7.5'). From reading the beginning of this thread, it was mentioned to treat the complete back wall and then all the way around the rest of the room up to ear level, all with 1" insulsheild. What if I'm doing flush mounted LCR behind my AT screen, should I still have some treatment on the front wall and flush mount the speakers with the treatment?


Also speaking of the 1" option all the way around. I will have two rows, the back row being 10" higher than the front, do I just "step up" the treatment to that level once I approach it? If I do that, sound is still bouncing around on the bare wall in front of the "step up", will that be a problem? Will the room even then be too "dead"?


Also, I am worried about all of the "bass trap" talk. A lot of the bass traps I see people make are HUGE! I just don't have room to shove 2' wide corner traps all the way around my room. In the rear, I will have more room for corner treatments, but the front will be tight. The edge of the screen will only be around 8-10" from the side walls. What would you guys recommend for a 4 corner treatment plan?


Well, that's pretty much it for now, I'm trying to stay simple yet effective with my treatment. Let me know what you guys think


----------



## nathan_h




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/0
> 
> 
> Hey guys! Soon I will be finishing my theater, but in the mean time, I wanted to get a good idea of what to do for room treatments. I have a couple of concerns though...
> 
> 
> I did read a bit of this thread already but there are so many different opinions and people with different room sizes and acoustical goals that it was hard to gather the right information for my small room. Here are my thoughts...
> 
> 
> My main concern comes from my room being so small (18' x 10' x 7.5'). From reading the beginning of this thread, it was mentioned to treat the complete back wall and then all the way around the rest of the room up to ear level, all with 1" insulsheild.



Don't do it 


Use thicker panels, but only at the first reflection points. The other school of thought is to use diffusion at those points on the side walls. Either way, few experts would suggest the plethora of non-broad band over absorption that a single inch all the way around the room up to ear height in a one inch thickness. That's too much high end energy lost without treating the full range of frequencies (thicker panels treat a broader range of frequencies).



> Quote:
> What if I'm doing flush mounted LCR behind my AT screen, should I still have some treatment on the front wall and flush mount the speakers with the treatment?



Sure but again think about something thicker than an inch. Two inches is better and four is even better.



> Quote:
> Also speaking of the 1" option all the way around. I will have two rows, the back row being 10" higher than the front, do I just "step up" the treatment to that level once I approach it? If I do that, sound is still bouncing around on the bare wall in front of the "step up", will that be a problem? Will the room even then be too "dead"?



Stick with the idea of treating first reflection points, which of course will change for each seat location and take into account the step up. Again, many people choose thick absorption for those points, while others make a good argument for diffusion, especially for the side wall reflection points.


Use the "mirror method". Look it up by searching this thread. It will help you locate those reflection points, some of which are on the ceiling and rear wall, in addition to the side walls, of course.



> Quote:
> Also, I am worried about all of the "bass trap" talk. A lot of the bass traps I see people make are HUGE! I just don't have room to shove 2' wide corner traps all the way around my room. In the rear, I will have more room for corner treatments, but the front will be tight. The edge of the screen will only be around 8-10" from the side walls. What would you guys recommend for a 4 corner treatment plan?



Effective bass trapping requires mass (thickness) and placement where the most bass resides. So people put big wedges in corners. It is still possible to get good results from a thick panel straddling the corners, or even from just a thick panel in the corner, flush with one wall, floor, or ceiling.


Remember, you don't have to use the wall-wall corner. There are wall-ceiling corners, wall-floor corners, etc. One of my favorites is the wall-floor junction under the screen, which is often an empty spec and can house, say, a foot thick panel as tall as the bottom of the screen, from side wall to side wall, and help with bass control a lot.


----------



## Exterous

Lots of great information in here guys - thanks for all the time you have taken!


A quick question - is there a downfall to only have a bass trap in one wall? Due to how the basement was constructed I have a door in the back left corner and can't place any treatments there. Would treating the back right corner throw everything off or would it still be worthwhile?


----------



## pepar




> Quote:
> Originally Posted by *Exterous* /forum/post/20710041
> 
> 
> Lots of great information in here guys - thanks for all the time you have taken!
> 
> 
> A quick question - is there a downfall to only have a bass trap in one wall? Due to how the basement was constructed I have a door in the back left corner and can't place any treatments there. Would treating the back right corner throw everything off or would it still be worthwhile?



Walls make "corners" with ceiling and floors, too ....


... one bass trap is better than none....


----------



## Exterous




> Quote:
> Originally Posted by *pepar* /forum/post/20710144
> 
> 
> Walls make "corners" with ceiling and floors, too ....
> 
> 
> ... one bass trap is better than none....



Heh - well, yes but since the door is compeltely in the corner there is no way I could put a bass trap along the ceiling or floor in that area. I plan on doing as much as my tiny budget allows but I wanted to make sure it wasn't counter-productive to be able to only do one back corner


Thanks!


----------



## mal01

I have made several of my own bass traps and wall panels, but now would like to add some diffusers, does anyone have any info or links they could shoot to me that would provide instructions on how to build them?


Thanks.


----------



## mtbdudex




> Quote:
> Originally Posted by *mal01* /forum/post/0
> 
> 
> I have made several of my own bass traps and wall panels, but now would like to add some diffusers, does anyone have any info or links they could shoot to me that would provide instructions on how to build them?
> 
> 
> Thanks.



Go to gearslutz.com, plenty there


----------



## mal01

Thanks, i`ll give it a try.


----------



## mtbdudex




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20711544
> 
> 
> Go to gearslutz.com, plenty there





> Quote:
> Originally Posted by *mal01* /forum/post/20712922
> 
> 
> Thanks, i`ll give it a try.



There is a good thread in the DIY Speakers and Subs forum here, DIY Sound Diffusers , definitely read that.

(my prior post was from iPhone and I can't copy/paste from urls there when using the AVS forum app)


----------



## Digital_Chris




> Quote:
> Originally Posted by *nathan_h* /forum/post/20708844
> 
> 
> Don't do it
> 
> 
> Use thicker panels, but only at the first reflection points. The other school of thought is to use diffusion at those points on the side walls. Either way, few experts would suggest the plethora of non-broad band over absorption that a single inch all the way around the room up to ear height in a one inch thickness. That's too much high end energy lost without treating the full range of frequencies (thicker panels treat a broader range of frequencies).
> 
> 
> 
> 
> Sure but again think about something thicker than an inch. Two inches is better and four is even better.
> 
> 
> 
> 
> Stick with the idea of treating first reflection points, which of course will change for each seat location and take into account the step up. Again, many people choose thick absorption for those points, while others make a good argument for diffusion, especially for the side wall reflection points.
> 
> 
> Use the "mirror method". Look it up by searching this thread. It will help you locate those reflection points, some of which are on the ceiling and rear wall, in addition to the side walls, of course.
> 
> 
> 
> 
> Effective bass trapping requires mass (thickness) and placement where the most bass resides. So people put big wedges in corners. It is still possible to get good results from a thick panel straddling the corners, or even from just a thick panel in the corner, flush with one wall, floor, or ceiling.
> 
> 
> Remember, you don't have to use the wall-wall corner. There are wall-ceiling corners, wall-floor corners, etc. One of my favorites is the wall-floor junction under the screen, which is often an empty spec and can house, say, a foot thick panel as tall as the bottom of the screen, from side wall to side wall, and help with bass control a lot.



Ok, so don't do the "up to ear level all the way around" idea but instead, treat just the first reflection points for all 6 seats? Also, if the speakers are flush mounted, why such thick absorbtion on that wall?


Again, the front is going to be tough with a screen and sub drivers close to the corners as well as the subs being close to the ground (top of stage). I am doing an IB setup which is why my front wall will be tight for treatment. Also, is all of this thick treatment (2"-4"), still insulshield?


Btw, is Dennis Erskine still around? I haven't seen any recent posts by him and I PM'd him but no reply yet.


----------



## nathan_h

Thickness gets you more even impact across a broad range of frequencies, which is typically what you want. If you use this absorption, you kill the high frequencies but don't control the mids -- which sucks the air out of the sound but doesn't effectively improve the overall room response.


I don't quite understand you insulshield question. Are you using that Johns Manville product instead of Owens Corning? Or are you referring to something else?


----------



## brandon_k_w

I have a huge canvas picture http://www.ikea.com/us/en/catalog/products/30173216 it's probably 6'x5'. Would these make decent acoustic panels? The canvas is about an inch thick, but it's hollow in the back, giving me an opportunity to add whatever material needs to be back there. Just thought it would be a good idea if possible...


----------



## Digital_Chris




> Quote:
> Originally Posted by *nathan_h* /forum/post/20722312
> 
> 
> Thickness gets you more even impact across a broad range of frequencies, which is typically what you want. If you use this absorption, you kill the high frequencies but don't control the mids -- which sucks the air out of the sound but doesn't effectively improve the overall room response.
> 
> 
> I don't quite understand you insulshield question. Are you using that Johns Manville product instead of Owens Corning? Or are you referring to something else?



I guess I'm only referring to what has been mentioned, I'm not really sure who makes the "insulshield" or what is exactly recommended, but just repeating what I've read in the first few posts of this thread.


Also, your paragraph above is still very confusing to me. What should I be treating my first reflections points with? I would be comfortable with doing 2" thick panels of some sort but just not sure what to make them out of, etc.


----------



## localhost127




> Quote:
> Originally Posted by *brandon_k_w* /forum/post/20733714
> 
> 
> I have a huge canvas picture http://www.ikea.com/us/en/catalog/products/30173216 it's probably 6'x5'. Would these make decent acoustic panels? The canvas is about an inch thick, but it's hollow in the back, giving me an opportunity to add whatever material needs to be back there. Just thought it would be a good idea if possible...



acoustic panels to combat what issues?

for typical absorption of early specular reflections, 1" of any material is not enough depth...


the fabric also needs to be acoustically transparent


----------



## localhost127




> Quote:
> Originally Posted by *mal01* /forum/post/20710757
> 
> 
> I have made several of my own bass traps and wall panels, but now would like to add some diffusers, does anyone have any info or links they could shoot to me that would provide instructions on how to build them?
> 
> 
> Thanks.


 http://www.subwoofer-builder.com/qrdude.htm 


technical reference:
http://www.subwoofer-builder.com/qrd.htm 


multiple periods are needed for good lobing... eg an array of 3x N7s vs a single N23 (but 3x N23s would be stellar).


anything more than that and it is wise to adhere to the barker code (inserting inverse panels. qrdude can handle all of this):
http://en.wikipedia.org/wiki/Barker_code


----------



## localhost127




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20733734
> 
> 
> I guess I'm only referring to what has been mentioned, I'm not really sure who makes the "insulshield" or what is exactly recommended, but just repeating what I've read in the first few posts of this thread.
> 
> 
> Also, your paragraph above is still very confusing to me. What should I be treating my first reflections points with? I would be comfortable with doing 2" thick panels of some sort but just not sure what to make them out of, etc.



can you source 'owens corning 703' or mineral wool (eg Rockwool of equivilant density) in your area? call around; it's much easier to source locally than to pay shipping online.


----------



## pepar




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20733734
> 
> 
> I guess I'm only referring to what has been mentioned, I'm not really sure who makes the "insulshield" or what is exactly recommended, but just repeating what I've read in the first few posts of this thread.
> 
> 
> Also, your paragraph above is still very confusing to me. What should I be treating my first reflections points with? I would be comfortable with doing 2" thick panels of some sort but just not sure what to make them out of, etc.


 http://www.spi-co.com/directory.html


----------



## mtbdudex




> Quote:
> Originally Posted by *brandon_k_w* /forum/post/0
> 
> 
> I have a huge canvas picture http://www.ikea.com/us/en/catalog/products/30173216 it's probably 6'x5'. Would these make decent acoustic panels? The canvas is about an inch thick, but it's hollow in the back, giving me an opportunity to add whatever material needs to be back there. Just thought it would be a good idea if possible...



I've seen these myself at ikea and had similar thoughts, then I tried the "official AT" test, ie see if you can breath thru it and nope they are non-AT.

Like localhost said, need to let sound freq pass thru, for absorption of mid/hi freq these won't work.


Gkacoustics and atsacoustics, among others have ready made AT panels for 1st reflection control/management.


Or, using spoonflower as a source to print a patten/image onto cotton weave you can DIY some.


Begins the q, what is your acoustic issue that you are trying to solve?


----------



## localhost127

fyi to remove any guesswork, the ETC response can always be used to determine whether a panel whose purpose is to absorb a specular reflection is truly absorbing the entire specular reflection and diminishing gain to the design requirement - and material, GFR/densitiy, thickness, angle-of-incidence, etc can be changed until the ETC shows that it is performing to said design requirements.


eg, if one is testing a particular printed fabric, it should only take a few moments to compare an ETC of a naked panel (exposed insulation) and then another ETC once the panel has been wrapped with the particular fabric.


it's really that easy. the ETC removes any guesswork.


----------



## nathan_h




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20733734
> 
> 
> I guess I'm only referring to what has been mentioned, I'm not really sure who makes the "insulshield" or what is exactly recommended, but just repeating what I've read in the first few posts of this thread.
> 
> 
> Also, your paragraph above is still very confusing to me. What should I be treating my first reflections points with? I would be comfortable with doing 2" thick panels of some sort but just not sure what to make them out of, etc.



For an understanding of treating first reflection points: http://realtraps.com/art_basics.htm 


For one approach to DIY panels: http://basstraps.net/index.php?topic=29.0


----------



## myfipie




> Quote:
> Originally Posted by *Exterous* /forum/post/20710041
> 
> 
> Lots of great information in here guys - thanks for all the time you have taken!
> 
> 
> A quick question - is there a downfall to only have a bass trap in one wall? Due to how the basement was constructed I have a door in the back left corner and can't place any treatments there. Would treating the back right corner throw everything off or would it still be worthwhile?



If the bass traps are behind where you sit it is fine. It is much for important to have symmetry in the front of the room.


Glenn Kuras


----------



## myfipie




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20734039
> 
> 
> I've seen these myself at ikea and had similar thoughts, then I tried the "official AT" test, ie see if you can breath thru it and nope they are non-AT.
> 
> Like localhost said, need to let sound freq pass thru, for absorption of mid/hi freq these won't work.
> 
> 
> Gkacoustics and atsacoustics, among others have ready made AT panels for 1st reflection control/management.
> 
> 
> Or, using spoonflower as a source to print a patten/image onto cotton weave you can DIY some.
> 
> 
> Begins the q, what is your acoustic issue that you are trying to solve?



It is GIK acoustics.


----------



## myfipie




> Quote:
> Originally Posted by Digital_Chris View Post
> 
> I guess I'm only referring to what has been mentioned, I'm not really sure who makes the "insulshield" or what is exactly recommended, but just repeating what I've read in the first few posts of this thread.
> 
> 
> Also, your paragraph above is still very confusing to me. What should I be treating my first reflections points with? I would be comfortable with doing 2" thick panels of some sort but just not sure what to make them out of, etc.



Yes for early reflection points you can use 2" panels. More about early reflections here.
http://www.gikacoustics.com/news_020209.html


----------



## Digital_Chris

I now have a very good understanding about early reflections. It seems that even 1" panels are good down to 500hz and 2", very good down to 250hz or so.


Do you think it would be worth it to do 2", or should I just do 1" to save money on materials because I won't really notice that 250-300hz difference?


----------



## localhost127




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20744371
> 
> 
> I now have a very good understanding about early reflections. It seems that even 1" panels are good down to 500hz and 2", very good down to 250hz or so.
> 
> 
> Do you think it would be worth it to do 2", or should I just do 1" to save money on materials because I won't really notice that 250-300hz difference?



that's not how it works.

do not break up 'specular reflections' in terms of frequency content.

and certainly do not 'assume' from 'charts' that a particular material or thickness with automatically yield those results in your room. have those charts taken into account angle of incidence?


the Envelope Time Curve (ETC) response (available via Room EQ Wizard - for free) will detail to you the total specular response of the room --- gain with respect to time. the ETC is the tool you use to identify early reflections, and to verify they have been attenuated once 'treatment' has been placed. the mirror trick is an approximate location for large boundaries, but you may be oblivious to other sources of early reflections which would otherwise go unnoticed. the ETC will detail you all of this - and one can work backwards to trace where specular reflections on the ETC are within the room since the speed of sound is a known value.


the ETC will detail to you the gain of the reflection with respect to time of the original signal. you do not "guess" with absorption coefficient charts. you place the panel and you measure with the ETC to see if the early specular reflection is attenuated to your design requirements (eg -20dB).


specular reflections are not to be broken up into individual frequencies.


if you believe that 1" of your selected material will truly absorb the entire specular reflection down to the gain you require, then by all means take an ETC of the room (one speaker at a time) - identify a particular early specular reflection on the ETC response, and place your panel. retest with the ETC and see whether the specular reflection has been attenuated to your design requirements. if not, make the panel thicker, space with a larger air-gap, or rotate the panel as such to change angle of incidence --- and test again. it's that simple. no need for all the constant guesswork.


it's amazing how many people are adamant about taming 'early reflections' and yet don't use the most beneficial tool in the toolbox to properly do so.


----------



## FOH




> Quote:
> Originally Posted by *localhost127* /forum/post/20744405
> 
> 
> .........
> 
> 
> it's amazing how many people are adamant about taming 'early reflections'



+1


----------



## pepar

FOH, you changed the meaning by dropping the full sentence. I know that there is some thinking "out there" that consider early lateral reflections beneficial, but localhost127's context was regarding not using a good tool for analyzing a problem and helping address it.


Jeff


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/20746151
> 
> 
> FOH, you changed the meaning by dropping the full sentence. I know that there is some thinking "out there" that consider early lateral reflections beneficial, but localhost127's context was regarding not using a good tool for analyzing a problem and helping address it.
> 
> 
> Jeff



I agree FOH completely changed the intent of localhosts127's post. The post implied that taming early reflection is useful, but that it's more complicated to get it right than most people assume.


On the other hand, I think you short shrift the contrarian thinkers ("out there"), who have shown conclusively in controlled tests that un-professional listeners do prefer lateral, parallel surface reflections in listening tests. (Professional listeners, eg, recording engineers, are split about preference.) Note that none of the studies claim more accuracy in the reproduced sound with untreated side walls, but simply some listener preference (which increases as one moves from a population of critical listeners to a population of casual listeners).


I'm currently working on testing the middle ground. I won't go back to bare side walls, but I am swapping out some absorption for diffusion, and am eager to see what that's like.


----------



## myfipie




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20744371
> 
> 
> I now have a very good understanding about early reflections. It seems that even 1" panels are good down to 500hz and 2", very good down to 250hz or so.
> 
> 
> Do you think it would be worth it to do 2", or should I just do 1" to save money on materials because I won't really notice that 250-300hz difference?



1" can work (I would space it off the wall a couple inches) but it is recommend it cover with 2" with a gap when possible. I generally try to cover a 4x4 area to make sure you have covered the area properly and give some room for moving your head.


----------



## localhost127

Quote:

Originally Posted by *nathan_h* 
I'm currently working on testing the middle ground. I won't go back to bare side walls, but I am swapping out some absorption for diffusion, and am eager to see what that's like.
or try the RFZ model like it's supposed to be done in the first place.

-use the ETC to measure the room's full specular response.

-establish the RFZ (attenuate all specular reflections within 20ms of the original signal). the ISD-gap is the length (in time) from the original signal until the next 'loud' reflection

-retest using the ETC to verify all early-reflections attenuated within the ISD-gap you have chosen (eg 20ms)

-add heavy diffusion on rear wall/rear side-walls such that the termination of the ISD is enabled by a haas kicker (loud specular reflection) and/or a *dense* diffused (laterally arriving) exponentially decaying soundfield.


the lateral returns are important, hence the need for 1D diffusers and not 2D which would otherwise forfeit precious sonic energy to the ceiling and floor which is not required.


this is why geometry (splayed walls) is used in the RFZ model to redirect (vs absorb) the early reflections to the rear of the room; preserving sonic energy that can will be used to add to the diffused sound-field.


whatever sounds best to you - experimentation is fun...but if you're going the RFZ route you need to follow through with the termination - not just blindly throwing up a few thin broadband absorption panels on the wall and calling that complete.


and also note when people say "diffusion" at first reflection points, that that doesn't make any sense. there's many types of diffusion - so when people say "diffusion" it is very vague. is it 1D? 2D? spatial dispersion only or spatial and temporal dispersion? what is the design freq? HF cut-off freq? are you taking into account that HF cut-off is lowered when angle of incidence moves away from 0*, and that it then acts like a "flat wall"? so when someone says "i tried diffusion at first reflection points and liked it" - you really need to be more specific as there are many ways to apply diffusion.


also, diffusers have an absorption coefficient (much like how a broadband absorber will have a reflection coefficient) - so a 2D diffuser (QRD/PRD) will lose a lot of energy because it's dispersed in 2 planes, and also viscous losses / resonation within the wells. so by all means a 2D diffuser (QRD/PRD) may in a sense "sound" like an absorber - even though it still is maintaining sonic energy within the room. i hope that makes sense.


have fun! post your results!


----------



## pepar

localhost127 - I keep bookmarking your pithy posts, but you keep adding more ....


----------



## nathan_h




> Quote:
> Originally Posted by *localhost127* /forum/post/20747247
> 
> 
> or try the RFZ model like it's supposed to be done in the first place.
> 
> -use the ETC to measure the room's full specular response.
> 
> -establish the RFZ (attenuate all specular reflections within 20ms of the original signal). the ISD-gap is the length (in time) from the original signal until the next 'loud' reflection
> 
> -retest using the ETC to verify all early-reflections attenuated within the ISD-gap you have chosen (eg 20ms)
> 
> -add heavy diffusion on rear wall/rear side-walls such that the termination of the ISD is enabled by a haas kicker (loud specular reflection) and/or a *dense* diffused (laterally arriving) exponentially decaying soundfield.
> 
> 
> the lateral returns are important, hence the need for 1D diffusers and not 2D which would otherwise forfeit precious sonic energy to the ceiling and floor which is not required.
> 
> 
> this is why geometry (splayed walls) is used in the RFZ model to redirect (vs absorb) the early reflections to the rear of the room; preserving sonic energy that can will be used to add to the diffused sound-field.
> 
> 
> whatever sounds best to you - experimentation is fun...but if you're going the RFZ route you need to follow through with the termination - not just blindly throwing up a few thin broadband absorption panels on the wall and calling that complete.
> 
> 
> and also note when people say "diffusion" at first reflection points, that that doesn't make any sense. there's many types of diffusion - so when people say "diffusion" it is very vague. is it 1D? 2D? spatial dispersion only or spatial and temporal dispersion? what is the design freq? HF cut-off freq? are you taking into account that HF cut-off is lowered when angle of incidence moves away from 0*, and that it then acts like a "flat wall"? so when someone says "i tried diffusion at first reflection points and liked it" - you really need to be more specific as there are many ways to apply diffusion.
> 
> 
> also, diffusers have an absorption coefficient (much like how a broadband absorber will have a reflection coefficient) - so a 2D diffuser (QRD/PRD) will lose a lot of energy because it's dispersed in 2 planes, and also viscous losses / resonation within the wells. so by all means a 2D diffuser (QRD/PRD) may in a sense "sound" like an absorber - even though it still is maintaining sonic energy within the room. i hope that makes sense.
> 
> 
> have fun! post your results!



Thanks. That's an excellent recipe for action. I had my room professionally evaluated once a while ago, but I need to make use of my computer, mic pre-amps, and get a calibrated mike and REW it myself.


The diffusion I am talking about are the Auralex Q'Fusor (which they say is "derived from combining a standard quadratic residue sequence with some other mathematical techniques to create a profile that optimizes scattering surfaces.... down to about 800Hz").


----------



## localhost127




> Quote:
> Originally Posted by *nathan_h* /forum/post/20748789
> 
> 
> The diffusion I am talking about are the Auralex Q’Fusor (which they say is "derived from combining a standard quadratic residue sequence with some other mathematical techniques to create a profile that optimizes scattering surfaces.... down to about 800Hz").



"other mathematical techniques". hmm. sounds like marketing.


do they provide: polar responses, absorption coefficients, scattering coefficients, normalized diffusion coefficients, etc?



> Quote:
> "and you have superior diffusion down to a frequency of around 800Hz!"



not sure how they are claiming 800hz "diffusion" with only 3" well depth. do they have a polar response @ 800hz?


have you toyed around with QRDude? if you are capable of some wood-work you would be much better off with constructing some schroeder QRD or PRDs. you can fine tune the design to your requirements (physical size, design freq, HF cut-off, etc)...and their performance is proven (and can be modeled with AMFG Reflex).


----------



## nathan_h

Auralex used to publish test data. It disappeared from their own web site a couple years ago, and from re-seller web sites some time in the past year.


----------



## localhost127




> Quote:
> Originally Posted by *nathan_h* /forum/post/20749156
> 
> 
> Auralex used to publish test data. It disappeared from their own web site a couple years ago, and from re-seller web sites some time in the past year.



right on.


if someone you know owns that product, ask if they could take measurements of it - and we could quickly model it into AMFG Reflex to gather an idea of the performance.


QRD/PRDs are tried and true. and the performance speaks for itself. you can also fine tune the design based on your requirements (design freq, period size, etc). if you're up for a challenge and have some work-working skills, maybe constructing your own would be something to look into


----------



## nathan_h

I like the DIY idea, though I admit: I'm better at rough carpentry (framing a wall) than fine finishing (I outsourced the mudding after I hung my own drywall).


----------



## FOH

Quote:

Originally Posted by *pepar* 
FOH, you changed the meaning by dropping the full sentence. I know that there is some thinking "out there" that consider early lateral reflections beneficial, but localhost127's context was regarding not using a good tool for analyzing a problem and helping address it.


Jeff
I certainly meant nothing malicious by doing so. I merely wanted to reiterate that there are individuals that are adamant about taming 'early reflections'.


Since DE and I first disagreed wrt early mirror point energy (I suggested it be attenuated, he claimed not necessarily), I've continued extended subjective experimentations with all my treatments down in order to gain as much perspective as possible in the only room that matters to me







. I've got Toole's Sound Reproduction, Everest's Handbook, I've read a great deal on Gearslutz and elsewhere,... I'm experimenting with several different mains, and mains optimization techniques. I like envelopment, spaciousness, however I value clarity and image specificity as well.


I've found localhost's posts very solid and quite enlightening wrt small room acoustics. Just as localhost's post have been very helpful to many, so has several other contributors here, and for that I'm grateful. Now retired, I've entered into this deep foray back into home audio because I decided to re-vamp the modest family AV room from bottom to top. I've always had small dedicated mixing/editing/mastering rig and the primary family system has been quite mid-fi in quality. For the family room, a new big IB, new mains, surrounds, front end source and pre/pro, and ultimately,..strong acoustic properties are all immediate priorities. This, in a non dedicated space has proved to be quite a challenge.


Anyway, I changed the quote to suit my point I wanted to make, that's all. I certainly didn't want to piss anyone off, as I'll likely be in need of more specific advice, from many of you, when the time comes










Thanks


----------



## pepar

^^^


----------



## mtbdudex

FOH, you'll like your IB sub, some guys here have dual line array 4 x 18FI (penngray is one in my memory). My modest 4x15 single line array never ceases to amaze me.


----------



## localhost127

 http://books.google.com/books?id=IDA...age&q=&f=false


----------



## FOH




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20751839
> 
> 
> FOH, you'll like your IB sub, some guys here have dual line array 4 x 18FI (penngray is one in my memory). My modest 4x15 single line array never ceases to amaze me.



I've very much enjoyed reading about your room in general, and more specifically your IB and various acoustical treatments. I do have a question for you or anyone; I've seen different acoustical cotton products and I really like the idea of trying them in a couple applications. I've got a great source for rigid fiberglass, however I looking for a good source for acoustical cotton,..any help in this regard?


Thanks


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20753216
> 
> http://books.google.com/books?id=IDA...age&q=&f=false




... bookmarked yet another of your posts!


Jeff


----------



## mtbdudex




> Quote:
> Originally Posted by *FOH* /forum/post/20754397
> 
> 
> I've very much enjoyed reading about your room in general, and more specifically your IB and various acoustical treatments. I do have a question for you or anyone; I've seen different acoustical cotton products and I really like the idea of trying them in a couple applications. I've got a great source for rigid fiberglass, however I looking for a good source for acoustical cotton,..any help in this regard?
> 
> 
> Thanks



I've used this as a source for acoustical cotton, http://www.acoustimac.com/index.php/...oinsul422.html 


From another post I made


> Quote:
> Well looking at the data it sure seems to have much better low freq absorption characteristics....
> http://www.acoustimac.com/index.php/...oinsul422.html
> 
> 
> 
> Quote:
> 
> 
> 
> Quote:
> Sound Absorption Coefficients (1/3 Octave Band Center Frequencies. HZ)
> 
> 
> Hz
> 
> 100 125 250 500 1000 2000 4000
> 
> 2" Thickness 0.38 .39 .63 1.18 1.11 1.06 1.09
> 
> 
> An even greener alternative to cotton insulation:
> 
> 
> Cotton insulation works as well as its fiberglass counterparts, however this material can be prone to mold and is not as biodegradable and recyclable as cellulose which is made from recycled newspapers and cardboard products.
> 
> 
> Better Performance than Fiberglass!
> 
> 
> Oh yes, it's true! This cellulose based insulation has even higher absorption coefficients than our standard insulation material, so not only is it more eco-friendly, it also outperforms its fiberglass and mineral wool counterparts hands down.
> 
> 
> 
> 
> 
> 
> 
> Quote:
> Freq 125 HZ 250 HZ 500 HZ 1000 HZ 2000 HZ 4000 HZ NRC
> 
> OC-703 (2") 0.17 0.86 1.14 1.07 1.02 0.98 1.00
> 
> Click to expand...
> 
> 
> 
> 
> 
> Quote:
> Freq 125 HZ 250 HZ 500 HZ 1000 HZ 2000 HZ 4000 HZ NRC
> 
> OC-705 0.16 0.71 1.02 1.01 0.99 0.99 0.95
> 
> Click to expand...
> 
> 
> 
> Click to expand...
Click to expand...


----------



## mtbdudex




> Quote:
> Originally Posted by *pepar* /forum/post/20754528
> 
> 
> ... Bookmarked yet another of your posts!
> 
> 
> Jeff



+1, +2, +3, ....:d


----------



## FOH




> Quote:
> Originally Posted by *mtbdudex* /forum/post/20754586
> 
> 
> I've used this as a source for acoustical cotton, http://www.acoustimac.com/index.php/...oinsul422.html
> 
> 
> From another post I made



Thank you sir.


----------



## myfipie




> Quote:
> Originally Posted by *FOH* /forum/post/20754397
> 
> 
> I've very much enjoyed reading about your room in general, and more specifically your IB and various acoustical treatments. I do have a question for you or anyone; I've seen different acoustical cotton products and I really like the idea of trying them in a couple applications. I've got a great source for rigid fiberglass, however I looking for a good source for acoustical cotton,..any help in this regard?
> 
> 
> Thanks



Is there a reason you want acoustical cotton over rigid fiberglass? If because of the air quality or "itchy stuff" stuff then check out Knauf rigid fiberglass.


----------



## FOH




> Quote:
> Originally Posted by *myfipie* /forum/post/20754842
> 
> 
> Is there a reason you want acoustical cotton over rigid fiberglass? If because of the air quality or "itchy stuff" stuff then check out Knauf rigid fiberglass.



Cool, I'm down the road from the Knauf plant


----------



## localhost127

dirt cheap deep pink fluffy corner traps (although they need to be fluffed out a bit better). and the plastic will reflect some highs back into the room.



http://imgur.com/lYBjo.jpg%5B/IMG%5D


----------



## FOH

Nice localhost!


Makes me wonder about the performance of the above mentioned big rolls of insulation, merely set into a room corners etc. Anyone familiar with such a temporary approach? It'd be interesting to know how well they perform. I realize they are bound a bit too tight, however I'd think they'd work to some degree.


You know how one brings a bottle of wine as one visits an acquaintance? Well, during these multi-sub, multi enthusiast subwoofer shootouts that are hosted on occasion, instead of wine, each attendee should bring a huge roll of insulation as a party favor. Strategically place them around the room, then upon completion of the GTG, the host gets to increase their attic insulation significantly


----------



## myfipie




> Quote:
> Originally Posted by *FOH* /forum/post/20758092
> 
> 
> Nice localhost!
> 
> 
> Makes me wonder about the performance of the above mentioned big rolls of insulation, merely set into a room corners etc. Anyone familiar with such a temporary approach? It'd be interesting to know how well they perform. I realize they are bound a bit too tight, however I'd think they'd work to some degree.
> 
> 
> You know how one brings a bottle of wine as one visits an acquaintance? Well, during these multi-sub, multi enthusiast subwoofer shootouts that are hosted on occasion, instead of wine, each attendee should bring a huge roll of insulation as a party favor. Strategically place them around the room, then upon completion of the GTG, the host gets to increase their attic insulation significantly



Rolls of fiberglass work. Kind of hard to make look nice though. Here is a room I found on you tube
http://www.youtube.com/watch?v=DsJVHcb9k4c


----------



## localhost127

such a waste when compressed. i made those 6 pillows with a little over 1roll of the _smaller_ rolls of insulation (!). the point of compressed is to make the traps very thick of low GFR - and to cover as much sq area as possible. leaving them compressed somewhat defeats all of those purposes. it looks like that guy is using the larger (standard) rolls of r30 insulation. i bet he could cover all corners with 48" faced (16"+ thick) fluffy traps in plastic wrapping with about 1/3rd of the rolls he has in that room stacked.


----------



## myfipie

I think you guys might really enjoy this video done by Zalan Schuster. I appreciate not everyone can speak Slovakian







but it has some audio demonstrations starting around 3:35. Before hand he has some nice before and after test graphs of the room.


----------



## pepar

Is that a ... railroad car???


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/20751038
> 
> 
> I'm experimenting with several different mains, and mains optimization techniques. I like envelopment, spaciousness, however I value clarity and image specificity as well.
> 
> 
> 
> Thanks



ive read some say that maintaining early reflections (in small acoustical spaces) offers more "spaciousness" or other characteristics. my question is, do large rooms not offer such "spaciousness"? large rooms do not have early-reflections, so why is it that in larger rooms we do not see an effort to _induce_ early reflections towards the listening position - if they are indeed so critical to spaciousness?


something fundamental that i think is constantly missed regarding attenuating early reflections is that you are changing the brain's perception of how large the room is. the longer the distance between the original signal and the first loud specular reflection, the larger the perceived room size. one can essentially "cheat" by artificially delaying this first specular reflection (in the time-domain) to make the room sound larger. this logic is taken to the extreme with anechoic spaces - where the first loud specular reflection after the original source is an infinite time away - making the room sound infinitely large. of course, our brains do not prefer this - but the brain has never been put in such a situation in the real world, anyways...as such an event (no reflections from any boundaries) does not exist in the real world that we would be constantly subjected to.


also perhaps what goes unnoticed is that in music, the `room' that the music was recorded in is _already present_ on the recording. early reflections in your listening space mask the sound of the room that the music was originally recorded in. you are hearing the reflections of your small acoustical space's boundaries _earlier_ than the reflections from the room the music was recorded in - and therefore are 'hearing' your room instead of being mentally transported into the room of the recording.


this is why in a control room, the ISD-gap needs to be a few ms longer than the ISD of the room of which the music was recorded in. otherwise, the control room itself is masking the sound of the recording. the design for making the control room as neutral as possible can be directly related to critical listening rooms - if that is one's goal.



have you anything to report regarding your own personal experimentation, FOH?


----------



## Brad Horstkotte

Quote:

Originally Posted by *localhost127* 
ive read some say that maintaining early reflections (in small acoustical spaces) offers more "spaciousness" or other characteristics. my question is, do large rooms not offer such "spaciousness"? large rooms do not have early-reflections, so why is it that in larger rooms we do not see an effort to _induce_ early reflections towards the listening position - if they are indeed so critical to spaciousness??
Aren't large rooms already by definition spacious? They wouldn't need to simulate largeness - they already are large.


----------



## Dennis Erskine

The difference lies in the delta between arrival times and the decay of the reflected sound over time/distance.


----------



## localhost127




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/20763247
> 
> 
> Aren't large rooms already by definition spacious? They wouldn't need to simulate largeness - they already are large.



my question was, if we are attempting to create 'spaciousness' in a small acoustical space (emulating a 'larger room'), then why do we inhibit early-reflections _which are not present in larger rooms_ (by definition).


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/20764658
> 
> 
> The difference lies in the delta between arrival times and the decay of the reflected sound over time/distance.



im just trying to understand what the _ideal specular response_ is when one induces (or maintains) early reflections in a small acoustical space - so i could recreate for my own personal testing.


can you elude any further to what the delta times should be?


i already have these answers for RFZ/LEDE room models, but for my own testing i'd need to know what the ideal specular response should look like when incorporating early-reflections, so i can verify that i am testing properly - for comparison. thank you,


----------



## GPBURNS




> Quote:
> Originally Posted by *localhost127* /forum/post/20758486
> 
> 
> such a waste when compressed. i made those 6 pillows with a little over 1roll of the _smaller_ rolls of insulation (!). the point of compressed is to make the traps very thick of low GFR - and to cover as much sq area as possible. leaving them compressed somewhat defeats all of those purposes. it looks like that guy is using the larger (standard) rolls of r30 insulation. i bet he could cover all corners with 48" faced (16"+ thick) fluffy traps in plastic wrapping with about 1/3rd of the rolls he has in that room stacked.





In theory - I have however gotten great results with corner stacking of these Cellulose bundles ($8 each- home depot) - has greatly reduced low end energy /bass decay in that corner (concrete)

- don't mind the mess -back of room is currently experimental center

I am now trying out different combos of 4 bass traps (made from OFI-48)

I have great low-end response now in room (34L/12.5w/7.5h with large opening in back ) but always tweaking


----------



## localhost127




> Quote:
> Originally Posted by *GPBURNS* /forum/post/20764823
> 
> 
> In theory - I have however gotten great results with corner stacking of these Cellulose bundles ($8 each- home depot) - has greatly reduced low end energy /bass decay in that corner (concrete)
> 
> - don't mind the mess -back of room is currently experimental center
> 
> I am now trying out different combos of 4 bass traps (made from OFI-48)
> 
> I have great low-end response now in room (34L/12.5w/7.5h with large opening in back ) but always tweaking



if you have enough of those Cellulose bundles lying around, may i suggest an experiment? stack them floor to ceiling like you have now, but stack them 2 units wide (you'll have to bring them out from the corner a bit to be able to fit 2x bundles wide - and they'll be straddling the corner)...but bringing them further away from the boundary and making a wider trap could really increase effectiveness.


may be a fun experiment if you're interested


----------



## GPBURNS




> Quote:
> Originally Posted by *localhost127* /forum/post/20764843
> 
> 
> .
> 
> 
> may be a fun experiment if you're interested



Yes - I found that as well as straddling my DYI bass Traps diagonally - floor to ceiling in that same corner all had very similiar results

I will probally end up doing corner chunks (fabric covered) and nicely made traps covering the back wall for nice compromise between performance and aesthetics


----------



## varun432

I Have Some Queries here in India.

My Room size is 25*15.5*9.5(height)(Sizes in feet).It's a basement room.It's

a corner part of basement i.e with no adjoining basement on 3 sides.My Room

is Bricked from all 4 sides.I have a lot of echo in my room.


I am getting Fibre Glass Sheets 2*3 feet

48kg/m3 in 2,3,4inch.

Q1 Which is preferred?

Q2 For Making Membreane Bass Traps, (as explained in Ethan Winers Page),Can I Use Laminate(For Decorative) on top of plywood?

Q3 Can sheetrock be used over fibreglass for more effectiveness?Can Someone Explain it's use? and How To Place it?

Q4 What Should Be Done to absorb all lower frequencies?

like changing Thickness of fibre glass, changing the air gap, placing the top plywood with some angle?


Q5 Should the plasterd bricked walls be first covered with plywood for placing glass wool or can be directly placed on the wall for medium and high frequencies absorbing?


Please Help Me With This and help me build my Theatre Room?


Thanks In advance


----------



## Ethan Winer

Q1: For corner bass traps, four inches thick is the best of your listed options. Even thicker is better, but that gets expensive. If cost is a limiting factor, you're better off with more 4-inch panels than fewer 8-inch panels. Proof here:

Density Report 


For reflection points two inches thick is adequate, though again four inches is better. More than four inches is probably not worth the added cost.


Q2: For a room that size I'd forget about wood panel traps and just use more of the same fiberglass panels.


Q3: If you put sheet rock in front of fiberglass, sound won't get to the fiberglass. So don't do that.


Q4: Fiberglass traps are not frequency selective, they just absorb less and less at lower frequencies. So the best solution is as thick as possible and with a similar air gap. If you could manage eight inches thick plus an eight-inch gap that would be fantastic. But most people can't give up that much space in their room.


Q5: There's no acoustic benefit to covering your brick with plywood.


As I mentioned in my email to you, I'm currently very busy writing a book about audio. So I'm not visiting forums much or seeing what's going on. If you have follow-up questions, hopefully some of the other experts here will be able to help you.



--Ethan


----------



## varun432




> Quote:
> Originally Posted by *Ethan Winer* /forum/post/20795578
> 
> 
> Q2: For a room that size I'd forget about wood panel traps and just use more of the same fiberglass panels.
> 
> 
> 
> 
> --Ethan



Wouldn't using Rigid fibreglass traps 2 Inch Thick all around the room(Or Atleast on 3 Walls, Leaving the Back Wall) make the room feel more dead?

Can I fill The Gap Between FibreGlass and Back Wall With Foam?

Can I Make Corner Bass Traps 5 inch Thick (2 2inches + 1 1inch)

For All of the above remember i am getting fibreglass without the reflective sheet here in India


----------



## myfipie




> Quote:
> Q4 What Should Be Done to absorb all lower frequencies?
> 
> like changing Thickness of fibre glass, changing the air gap, placing the top plywood with some angle?



There really is not way to absorb "ALL" lower frequencies, but if you are looking for the best way then filling the corners or making false soffit bass traps is far the best way to go. The following layout would have both false soffit bass traps and filling the corners.
http://www.gikacoustics.com/room_setup.php


----------



## pepar

Glenn, what is your position on diffusors at the first reflection points in lieu of absorbers? My context is with THX-certified speakers (and all that implies).


Jeff


----------



## Digital_Chris

Hey guys, hopefully this is a question that doesn't come up frequently, I have yet to find anything on this specific idea.


Regarding corner bass traps, (e.g. superchunks), if I can't fit a good sized trap in my front corners, would it be a better idea to turn those 90 angles into multiple 135 degree angles (my math might be off) by adding a reflective panel across the corner, floor to ceiling? The end result will look like a corner bass trap, just smaller and reflective only.


I guess my main question will be, for bass control, would this small amount of added reflection give better results than small corner bass traps?


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20798309
> 
> 
> Glenn, what is your position on diffusors at the first reflection points in lieu of absorbers? My context is with THX-certified speakers (and all that implies).
> 
> 
> Jeff



not enough data. how far are the boundaries from the listening position? what is the total time of flight of the first order reflections? etc. how long have you chosen your ISD-gap to be?


and one should note also, with typical QRD/PRDs, by changing angle of incidence away from 0*, you're lowering the HF-cutoff.


so if you placed a diffuser flat on the side-wall at first-reflection points, incident energy will likely be in the area of 45* - which will decrease the width of the wells seen by HF wavelengths, *decreasing* the HF cut-off point (eg the point where HF specular energy 'sees' a flat wall vs the diffusive surface.


might be something that needs to be taken into consideration based on your design.


----------



## localhost127




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20807780
> 
> 
> Hey guys, hopefully this is a question that doesn't come up frequently, I have yet to find anything on this specific idea.
> 
> 
> Regarding corner bass traps, (e.g. superchunks), if I can't fit a good sized trap in my front corners, would it be a better idea to turn those 90 angles into multiple 135 degree angles (my math might be off) by adding a reflective panel across the corner, floor to ceiling? The end result will look like a corner bass trap, just smaller and reflective only.
> 
> 
> I guess my main question will be, for bass control, would this small amount of added reflection give better results than small corner bass traps?



there is some LF benefit to having a membrane on the outer edge of a broadband porous absorber to cure LF modal issues, but nothing terribly conclusive that i've found (outside of particular designs which are designed to incorporate the membrane). you also have the problem of the corner trap being broadband, and thus absorbing LF energy as well as mid/HF specular energy - which may over-deaden the room. many will add a reflective membrane to the outer face of the corner trap to reflect some mid/HF content back into the room, or add slatted strips ( http://www.gearslutz.com/board/studi...esonators.html ). some also purchase 'faced' OC703, as the faced acts as a reflective membrane.



> Quote:
> I guess my main question will be, for bass control, would this small amount of added reflection give better results than small corner bass traps?



regarding LF absorption, i would focus on increasing the depth of the absorber. it will perform far better than simply applying a membrane - but the membrane may be an option if you wish to reflect some specular energy back into the room. i would not say that adding any sort of 'reflection' will give you better LF absorption. thickness of the absorber (absorber + airgap) is the primary variable regarding performance of porous insulation (velocity-based) absorbers.


----------



## Digital_Chris

Another way I could ask my question is, if I don't have enough space to make a properly sized corner bass trap (e.g. 17x17x24 or larger), would some diffusion alone (no absorption behind) be my next best thing in those corners to treat the bass waves that collect there? I just don't have the room up front to properly treat my corners for bass so I'm curious as to what my next best option is.


Thanks for your thoughts so far though


----------



## localhost127




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/20808056
> 
> 
> Another way I could ask my question is, if I don't have enough space to make a properly sized corner bass trap (e.g. 17x17x24 or larger), would some diffusion alone (no absorption behind) be my next best thing in those corners to treat the bass waves that collect there? I just don't have the room up front to properly treat my corners for bass so I'm curious as to what my next best option is.
> 
> 
> Thanks for your thoughts so far though



no - diffusion is for breaking up loud specular reflections into many reflections of lower gain, and dispersing these spatially and temporally. diffusers address an entirely different problem inherent within small acoustical spaces. for bass, you need low-freq absorption (attenuation).


can you add thick porous insulation to any other corner in your room? bear in mind there are 12 corners in a rectangular room.


----------



## Digital_Chris

Ok, for bass traps, I can and plan to do 17x17x24 wedges stacked in the rear corners floor to ceiling, I just don't have nearly that amount of room in the front corners. I can possibly do some roughly 10x10x16 wedges stacked up 2 feet from the ground in the front corners but not sure if it would do enough bass control to overcome the negative aesthetics it will produce. Other than those 4 major corners, I really don't want to put any more corner traps in the room because of aesthetics and space limitations.


Besides the superchunks, I will be doing fiberglass panels at all first reflection points including a couple on the back wall but plan to leave the ceiling alone, most likely. I am still undecided on whether to treat the whole front wall or not. If I do, I need to come up with a plan that will not take up too much space and work well with my flush mounted speakers and subs.


For the front wall, I planned on installing double plywood over the framing followed by double drywall, I think. Before the drywall goes up, I will make my cutouts for my subs and mains, then put the drywall on and cut out the same holes for the drivers. If I go this route, I don't know how to treat the front wall with all speakers flush mounted. Ideas are welcome. I can also take a picture to represent what my drivers look like in the framed wall if that will help...


Here is a shot with the mains resting where they will be, not pictured will be (4) 18" drivers flush mounted for the LF department. Those will be the problem. With the LCR's, I can push them out an inch or two past the drywall and then cover the wall and around the LCR's with rigid insulation, the sub drivers I cannot do that as easily unless I make "spacers" for them to push them out past the drywall...


----------



## Digital_Chris

Ahhh, wait a minute. I've just thought of something. Instead of doing the whole front wall with double 3/4 ply, I can do from the subs on up with one layer of 3/4 ply and then the baffle for the subs, I can make a thicker baffle of say, 3 layers of 3/4 ply, that way I don't have to make individual spacers for the sub drivers. Yes, that should work out better and will be easier to treat the wall


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/20798309
> 
> 
> Glenn, what is your position on diffusors at the first reflection points in lieu of absorbers? My context is with THX-certified speakers (and all that implies).
> 
> 
> Jeff



Sorry for the delay on this. In my book, unless you have a very wide room (over 20 feet) I would always stick with absorption. The point is you do not want any of the reflection at all.

localhost127 gave a great answer btw.


----------



## myfipie




> Quote:
> Ok, for bass traps, I can and plan to do 17x17x24 wedges stacked in the rear corners floor to ceiling, I just don't have nearly that amount of room in the front corners. I can possibly do some roughly 10x10x16 wedges stacked up 2 feet from the ground in the front corners but not sure if it would do enough bass control to overcome the negative aesthetics it will produce. Other than those 4 major corners, I really don't want to put any more corner traps in the room because of aesthetics and space limitations.



16" wide traps will help but you really do want them larger if at all possible. As far as aesthetics, have you thought about soffit bass trapping? That will yield over all the best results and look pretty nice in a room. Here is a picture of what I mean. They could go in the wall to wall corner and or the ceiling to wall corner around the room. The picture shows the upper ceiling the wall corner.


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/20822996
> 
> 
> Sorry for the delay on this. In my book, unless you have a very wide room (over 20 feet) I would always stick with absorption. The point is you do not want any of the reflection at all.
> 
> localhost127 gave a great answer btw.



Thanks, Glenn. That was always my understanding, but I have read some things that at least modify that and have seen a pro or two post here that it depends on the off-axis characteristics of the front speakers. If that response is flat but attenuated, then those reflections are desirable. If not, then not desirable. My contextual reference to THX Ultra certified speakers was speaking to the off-axis performance.


This is very confusing ...


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20823483
> 
> 
> Thanks, Glenn. That was always my understanding, but I have read some things that at least modify that and have seen a pro or two post here that it depends on the off-axis characteristics of the front speakers. If that response is flat but attenuated, then those reflections are desirable. If not, then not desirable. My contextual reference to THX Ultra certified speakers was speaking to the off-axis performance.
> 
> 
> This is very confusing ...
> 
> 
> Jeff



instead of guessing what the off-axis response is of a particular speaker in your particular room at your particular listening point, why not just measure with the Envelope Time Curve (ETC) response - which will clearly dictate to you the gain (dB) and where in time the specular energy (reflections) impede the listening position with respect to the original signal. it's that easy. and while you're at it - you'll have the whole picture of your room's entire specular response (visibility of all of the early reflections, the decay trail, etc).


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20823501
> 
> 
> instead of guessing what the off-axis response is of a particular speaker in your particular room at your particular listening point, why not just measure with the Envelope Time Curve (ETC) response - which will clearly dictate to you the gain (dB) and where in time the specular energy (reflections) impede the listening position with respect to the original signal. it's that easy. and while you're at it - you'll have the whole picture of your room's entire specular response (visibility of all of the early reflections, the decay trail, etc).



So are you allowing that there is a set of circumstances where diffusion is appropriate for front side first reflections?










Where can I find information that will help me interpret the data that is generated with the measurement you cite?


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20823683
> 
> 
> So are you allowing that there is a set of circumstances where diffusion is appropriate for front side first reflections?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Where can I find information that will help me interpret the data that is generated with the measurement you cite?
> 
> 
> Jeff



yes - as noted many times that not all first-order reflection points are necessarily early reflection points.


the Inter Signal Delay (ISD) gap, is the length of time after the original signal that one creates an anechoic listening space. for example, if one determines their ISD-gap to be 20ms, then that means any specular energy impeding that 20ms ISD-gap needs to be attenuated.


if the sidewalls are far enough away that the first-order reflection arrives outside of this 20ms window, then you do not necessarily need to attenuate it.


diffusers have an absorption coefficient. a 2D PRD is going to function like an absorber by 1) viscous losses from the wells / resonation and 2) because it is taking a single, loud specular reflection and dispersing it in many directions - so the reflection off of a diffuser will be much lower in gain.


now, one needs to measure to identify whether the gain is low enough for the design requirements. (eg., all energy above -20dB within 20ms of original signal attenuated).


there are multiple reasons for attenuating early reflections. 1) is to allow the brain ample time to digest the original signal so restrict smearing and clarity issues of early reflections. 2) is comb-filtering response in the specular region via combination (summation) of original signal + reflections which cause constructive and destructive interference (nulls/peaks). 3) stereo imaging (off-axis energy from left speaker reflecting off right wall and entering right ear).


the issue with diffusion at the first reflection point (if it is an early reflection point) is that if the specular (albiet diffused) reflection off of the diffuser is still high enough in gain, it will still combine at the listening position to cause comb-filtering. Acoustic Absorbers and Diffusers ( http://www.google.com/search?source=...w=1441&bih=539 ) actually has a section in which a poly-diffuser is used at first-reflection point, and since there is no temporal dispersion and the spatial dispersion was still high in gain, it was still causing comb-filtering response issues at the listening position.


blackbird studio c (ambechoic room response) for example - now the massive-order PRD diffusers that make up that room are at "first reflection points" - the difference is, the returned energy from those diffusers is a whopping -30dB down! so even though this energy is arriving within the 20ms window of original signal (for example), the energy is so low in gain it still satisfies the requirements.


now bear in mind when we attenuate these early reflection we're actually emulating a particular room model (which has very specific criteria regarding the room's response). and establishing this time-zone of which no early specular energy impedes is only one part to the story. once this time window is over, we terminate with energy from within the room (eg diffusive decay, haas kicker, etc). the termination is very important - as is how the rest of the energy decays in the room. since diffusion is important, and since diffusion requires a lot of energy to begin with (of which there is a finite amount of it in the room) - this is why many use large reflective objects at first reflection points to redirect (not absorb) the energy away from the listening position and towards the rear of the room where it can be diffused and returned to the listening position to terminate the ISD (eg., after 20ms).


redirecting this energy from first-reflection points provides more energy (denser) diffused return - which is very important.


----------



## Roger Dressler




> Quote:
> Originally Posted by *pepar* /forum/post/20254920
> 
> 
> How about diffusion on the ceiling, especially, and the side walls .. instead of absorption .. with THX Ultra speakers .. and the dispersion control that accompanies that certification?



I thought THX speakers were "normal" wrt horizontal dispersion (wide) and narrowed only in the vertical direction. So, for lateral reflections, do the same as for any other speaker system.


Even though THX speakers reduce the off-axis sound in the vertical direction, that sound is usually not very flat, spectrally, which is what led to their poor subjective qualities for music playback. All this to say that you might still want to kill those floor/ceiling reflections rather than assume the speaker itself takes care of them.


----------



## pepar




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20824628
> 
> 
> I thought THX speakers were "normal" wrt horizontal dispersion (wide) and narrowed only in the vertical direction. So, for lateral reflections, do the same as for any other speaker system.



Roger, you'd know more about it than I, but I _thought_ that there was a THX criteria that spoke to the linearity of off-axis horizontal response as well as the amount of vertical dispersion.



> Quote:
> Even though THX speakers reduce the off-axis sound in the vertical direction, that sound is usually not very flat, spectrally, which is what led to their poor subjective qualities for music playback. All this to say that you might still want to kill those floor/ceiling reflections rather than assume the speaker itself takes care of them.



I presently have the ceiling reflections absorbed but was looking for locations to swap in diffusors for absorbers to extend the decay time in my room, especially in light of the additional superchunk corner traps that I am adding in the rear that will move more surface from reflective to absorptive.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/20823885
> 
> 
> yes - as noted many times that not all first-order reflection points are necessarily early reflection points.
> 
> 
> the Inter Signal Delay (ISD) gap, is the length of time after the original signal that one creates an anechoic listening space. for example, if one determines their ISD-gap to be 20ms, then that means any specular energy impeding that 20ms ISD-gap needs to be attenuated.
> 
> 
> if the sidewalls are far enough away that the first-order reflection arrives outside of this 20ms window, then you do not necessarily need to attenuate it.
> 
> 
> diffusers have an absorption coefficient. a 2D PRD is going to function like an absorber by 1) viscous losses from the wells / resonation and 2) because it is taking a single, loud specular reflection and dispersing it in many directions - so the reflection off of a diffuser will be much lower in gain.
> 
> 
> now, one needs to measure to identify whether the gain is low enough for the design requirements. (eg., all energy above -20dB within 20ms of original signal attenuated).
> 
> 
> there are multiple reasons for attenuating early reflections. 1) is to allow the brain ample time to digest the original signal so restrict smearing and clarity issues of early reflections. 2) is comb-filtering response in the specular region via combination (summation) of original signal + reflections which cause constructive and destructive interference (nulls/peaks). 3) stereo imaging (off-axis energy from left speaker reflecting off right wall and entering right ear).
> 
> 
> the issue with diffusion at the first reflection point (if it is an early reflection point) is that if the specular (albiet diffused) reflection off of the diffuser is still high enough in gain, it will still combine at the listening position to cause comb-filtering. Acoustic Absorbers and Diffusers actually has a section in which a poly-diffuser is used at first-reflection point, and since there is no temporal dispersion and the spatial dispersion was still high in gain, it was still causing comb-filtering response issues at the listening position.



Well then what are the handful of respected scientists puffing on when they say that lateral reflections are good/desirable/whatever-they-termed-them?


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20824742
> 
> 
> Well then what are the handful of respected scientists puffing on when they say that lateral reflections are good/desirable/whatever-they-termed-them?
> 
> 
> Jeff



yes, the diffused sound-field that terminates the ISD is lateral (usually accomplished with 1-dimensional Quadratic Residue Diffusers or Primitive Root Diffusers (Schroeder QRD/PRDs) - which (if mounted with vertical wells) will spatially diffusive in the horizontal plane.


you effectively want to create an anechoic space for a set amount of time (you hear the original signal only, and all reflections within the ISD gap are attenuated) - then, after the set amount of time (eg, 20ms) - you terminate the ISD with a STRONG, dense, laterally arriving - exponentially decaying diffused sound-field. this is why the development of the QRD diffuser (which also offers temporal dispersion in the time-domain to assist with the decay trail) was so important.


there is also the Haas effect, which some add a reflective panel on the rear of the wall to terminate the ISD with a loud, specular reflection and then followed by the diffused decaying sound-field.


you really cannot do any of this without the ETC response graph. it is essential to 'see' what the specular energy in the room is doing.


----------



## pepar

It's almost enough to make me only use in-ear monitors ...


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20824789
> 
> 
> It's almost enough to make me only use in-ear monitors ...



what are you confused on?


the straight vector from the acoustic center (speaker) to your ears will always be the shortest path and thus arrive at your ears first.


other reflections will take a longer path, and as such - will arrive slightly longer in time at your ears after the original signal.


one particular room model that everyone here is emulating by attenuating 'early reflections' relies on establishing a static length in time of which no ("early") specular energy will impede.


if this were an anechoic room, the ISD would be infinity (no reflections ever arrive at the listening position - emulating an infinitely large room )


but, we do not want to create a dead space. we wish to merely create a dead space for a brief moment in time (as such to make the room sound 'bigger' along with addressing the other issues (comb-filtering) i stated above).


once this 'anechoic brief moment in time' is over with, we DO want some other energy besides the direct signal to hit the listening position and provide the decay. this is the termination of the ISD - and these rear, lateral arriving diffuse sound-field will provide envelopment.


----------



## pepar

Quote:

Originally Posted by *localhost127* 
what are you confused on?

*the straight vector from the acoustic center (speaker) to your ears will always be the shortest path and thus arrive at your ears first.


other reflections will take a longer path, and as such - will arrive slightly longer in time at your ears after the original signal.*


one particular room model that everyone here is emulating by attenuating 'early reflections' relies on establishing a static length in time of which no ("early") specular energy will impede.


if this were an anechoic room, the ISD would be infinity (no reflections ever arrive at the listening position - emulating an infinitely large room )


but, we do not want to create a dead space. we wish to merely create a dead space for a brief moment in time (as such to make the room sound 'bigger' along with addressing the other issues (comb-filtering) i stated above).


once this 'anechoic brief moment in time' is over with, we DO want some other energy besides the direct signal to hit the listening position and provide the decay. this is the termination of the ISD - and these rear, lateral arriving diffuse sound-field will provide envelopment.
I am not confused about *that* at all. It is the discussion that alternates between "kill them all" and "let the good through" and can be seen at work in this quickly googled post from Sanjay.

http://www.avsforum.com/avs-vb/showt...3#post20011283 


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/20824893
> 
> 
> I am not confused about *that* at all. It is the discussion that alternates between "kill them all" and "let the good through" and can be seen at work in this quickly googled post from Sanjay.
> 
> http://www.avsforum.com/avs-vb/showt...3#post20011283
> 
> 
> Jeff



there are *defined* room models and there are mixtures of randomly placed 'treatments' which will have unpredictable results until subjected by the listener (and even those ideas (types of treatments and their placement with respect to the specular region) are not necessarily transferable between rooms or users)


these room models (that many here are emulating whether they realize it or not - and as such, are not emulating all aspects) - have specific criteria for the room's specular total response - as defined by the ETC.


if you are not choosing a specific room model or response, then you can place 'treatments' at will and make a subjective conclusion regarding your own taste.


what do you wish to do?


----------



## localhost127

id note also that this increase in perceived "spaciousness" from early (lateral) reflections is due to virtual images.


have you tried eliminating these early reflections *along with* terminating the ISD with a dense, diffused _laterally arriving_ sound-field? you may find that the localization cues (Haas effect) and the surrounding envelopment of the diffused energy off the rear and rear side walls is quite beneficial.


----------



## pepar

I am wasting bandwidth until I do some measurements. Until then, I'll lurk....


----------



## localhost127

Quote:

Originally Posted by *pepar* 
I am wasting bandwidth until I do some measurements. Until then, I'll lurk....



















the ETC will detail you (clear as day) all of the specular reflections (be they early or not - that's up to the user's defined ISD length) along with the decay trail.


all this talk about mirror-points and attenuation and thin absorption... there is a tool that easily details all of this. it really would save endless amounts of discussion if people were to start taking measurements of their room. it seems to be completely expected for someone to provide frequency response (which in itself doesn't tell you much) - yet any other measurement (even from the same software suite!) automatically shuts down the conversation. strange strange.


----------



## localhost127

http://imgur.com/2sxgd.jpg%5B/IMG%5D


----------



## localhost127

pepar,

here is some more commentary regarding the importance of the termination of the ISD.


SAC has been so kind as to hand this information to us on a silver platter. one must understand the importance and sympathy of the TOTAL specular response (the ISD + the termination + the way the energy decays) as a whole.



> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> the ISD termination should be a maximum of 12 dB SPL below the direct signal level. ... Up to an ISD length of ~25ms.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> The preponderance of the termination as well as the exponentially decaying diffuse tail energies should arrive laterally.
> 
> 
> To quote from Schroeder: _"..research, based upon a subjective evaluation of the acoustics of 20 major European concert halls, has shown that many modern halls have poor acoustics because their ceilings are low relative to their widths. Such halls do not provide the listener with enough laterally traveling sound waves - as opposed to sound traveling in front/back direction and arriving at the listener's head in his "median" plane (the symmetry plane through his head). Such median plan sound, of course gives rise to two very similar acoustic signals at the listener's ears, and it is thought that the resulting excessive "binaural similarity" is responsible for the poor acoustical quality."_
> 
> 
> Also, to keep it short...
> *The purpose of the ISD termination is to REMOVE the localization cues of the later arriving energies and to reinforce the localization cues of the direct energy.*





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> Also, in the diagram, note the delta between the separate source and image shift thresholds and compare that with the level of the ISD termination.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> A late arriving reflection, if of sufficient gain, is perceived as a destructive element that skews localization and tonality. (And in a Large Acoustical Space, if after 80 ms, it is perceived as a distinct echo). Hence the use of the ETC in identifying and mitigating them and the use of the Haas kicker - the ISD termination - to reinforce the direct signal localization prominence.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> As the intensity of the ISD termination has a significant impact on the sense of liveliness of the space, while the laterally arriving semi-reverberant soundfield and to the sense of space (size) of the room.
> 
> 
> The ISD balances between the comb filter interval (CFI) featuring time delays within the first few ms (say a meter) that cause significant spatial misdirection via comb filters, and the ISD where the establishment and support of the time region capable of supporting a partial Haas effect as supported by Madsen's research.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> As far as the two issues regarding orientation of later arriving diffuse energy and the psycho-acoustical requirements of relative levels of arriving energy relative to the direct signal necessary to trigger individual behaviors. (That is not to say that we know everything there is to know! But it is what research we currently have.)
> 
> 
> Yes, it is beneficial to increase the degree of later arriving, laterally directed, exponentially decaying, diffuse energy return in that it increases the sense of space in the room. Bu this is optimally accomplished by a combination of controlled dispersion speakers minimizing boundary incidence (and including soffit mounting optimizing Q), limited strategic absorption, *and the redirection of energy maximizing its content until it is diffused back into the listening position. Thus it is an issue of maximally conserving energy and minimizing losses in the finite energy supplied.* Thus this also implies the judicious use of lossy diffusion as well such that reflection is the choice until such time as diffusion is strategically introduced.
> 
> *The higher ISD termination relative to the direct signal within the Haas time interval both increases the sense of liveliness in the room while also increasing the Haas effect and direct signal localization process while simultaneously minimizing the destructive localization and tonality cues of any later higher gain reflections.*
> 
> 
> But as to the basic relationships as defined in the LEDE model, they have all been researched and predicated upon psycho-acoustics principles - not simply assumptions. And there is not much point of debating them anecdotally unless we have new psycho-acoustic research that either invalidates or modifies concepts that are directly supported by the implementation of the model.
> 
> 
> With the advancement in the complexity of diffusive treatments, there has been the corresponding advance in the integration of the soundfields, but there has not been a corresponding 'replacement' discrediting of the basic psycho acoustical concepts. Instead the models have simply become more tightly integrated and complex. We are now able to generate much more complex mixed soundfields and this has enabled the various models to become more effective, as evidenced in the extreme low level and extremely complex diffusion incorporated in the ambechoic model.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> My general point remains that the issues with retaining sufficient energy to reach the prescribed ISD termination levels requires judicious attention to detail at each stage of the signal process, including a careful management of boundary incidence, reflection/redirection, and a care in the optimal use of lossy diffusive techniques in the process of redirecting the later arriving diffuse energy laterally back to the listening position.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> 
> All of the variables listed as simply steps in the process whereby the energy from the speaker propagates and is either redirected or absorbed.
> 
> 
> Our larger task is on the one hand to have only the direct signal arrive at the listening position during the ISD gap, while ALSO, redirecting the indirect energy in such a manner as to preserve as much energy as possible, to return the energy from a lateral orientation in a diffuse manner at a level within at least 12 dB of the direct signal level.
> 
> 
> Thus, be it the over application of (broadband) bass trapping, broadband specular absorption, and/or diffusion (and less diffusion, as the process of diffusion has a relatively high 'absorptive' loss component.
> 
> 
> Whereas it is common to hear the notion that one cannot apply too much bass or broadband absorption, this is simply is not the case with this acoustic response model! Here we require very judicious application of the treatment sufficient to tailor both the direct response as well as the indirect response.
> 
> 
> 
> Thus controlled Q/dispersion radiation from the speakers minimizing the need for absorption, bass trapping must be frequency specific, specular absorption must be surgical, and diffusion efficient (diffusing diffusion is a big energy loss) while also effectively reflecting/redirecting the energy such that after a suitable time it can be redirected laterally in a diffuse manner back to the listening position with sufficient gain is a challenge in energy conservation.
> 
> 
> Each step contributes to the losses, and with each step we are faced with economizing to preserve the energy. The best term that comes to mind is "surgical" - to do just what is necessary to prevent anomalous behavior while preserving the later arriving energy.
> 
> 
> And while the perils of excessive absorption are rather obvious in this regard, so too are the issues with diffusion - not because diffusion is bad, but rather because it is a rather inefficient process with higher losses than many would assume. And the emphasis shifts a bit from 'are the absorbers large enough', to the balance with low loss reflective and re-directive surfaces, or moving surfaces to avoid incidence entirely as was done in the RFZ implementation of the LEDE.
> 
> 
> Its a balancing act at each step in the process.





> Quote:
> Originally Posted by *SAC* /forum/post/0
> 
> *The length of the ISD gap maximizes intelligibility during the Haas interval where multiple arriving signals are merged/smeared into one event in what Heyser called 'time smear distortion'.*
> 
> 
> I don't see that as ever being good or acceptable.
> 
> 
> Also, in a control room or critical listening space, *the ISD also allows one to experience the reproduction of the recording space in total before the incursion of the control room or listening space.*
> 
> *The termination of the ISD does several things as well psycho-acoustically. It provides the sense of liveliness to the listening space. Second, it aids in localization by 'removing' the localization and tonality shifting cues from later arriving signals - causing the focus and localization to lock onto the direct signal. And the later arriving exponentially decaying diffuse soundfield adds to the sense of space/size to the listening environment.* This is the bonus above and beyond what a dead room affords you.
> 
> 
> So in fairness, while its hard to say "which one", I guess one would have to acknowledge the primacy of the ISD regarding fundamental localization, imaging and intelligibility of the direct signal itself. As the termination and later arriving diffuse soundfield further augment this.
> 
> 
> The termination and latter arriving lateral diffuse sound field further augments the localization and imaging, accurate tonality and provides a sense of space to the listening environment.


----------



## saprano

Should i use 2" or 4" panels for the back wall? About to order from ATS. The 24x24.


----------



## pepar

Four inches if you can. For first reflection point, right?


----------



## saprano

For the first reflection points im going to use 2" 24x48. The 24x24 is for the back wall above my couch. Need about 3 to cover the area.


So 4"? Thanks.


----------



## myfipie

Yes 4" but you are going to want to cut out the backs and space it from the wall a few inches.


----------



## saprano

I was just going to ask that question.


They sell them with or with out backs. But ATS says they're pretty much the same unless trying to absorb bass?




> Quote:
> Q: Why do the panels have a solid wood back?
> 
> 
> 
> A: The 1/4" wood back provides strength for the panel, and makes it easy to hang the panels on the wall, or attach hardware such as hinges, hooks, or other hangers.Acoustically, the solid back against the wall is about the same as the panel with no back against the wall. Either way the sound enters the front of the panel, is reflected by the back and/or wall, and exits through the front again.Where the back can be undesirable is if you are trying to absorb bass and you want an air gap behind the panel. This air gap is to allow the sound to travel through the panel, some distance in the air gap, reflect from the wall, back through the air gap, and back through the panel. That distance is helpful in absorbing low frequencies (because they have long wavelengths). Most of our customers mount our panels against the wall for broadband absorption and control of reverb, and this works very well.We have had the panels absorption tested (solid back and all) by Riverbank Acoustical Laboratories and they rate very highly. See the test results on our 4-inch panels for the absorption coefficients at various frequencies.Our 4-inch panels are available with fabric-covered open backs. If you plan to install your panels across a corner or spaced away from the wall for an air gap, we recommend that you select the open back option when adding the panels to your shopping cart. This option is not available in 2-inch panel construction.



Shouldn't i buy bass traps to handle that? I was gonna go for solid back. No?


----------



## saprano

Also i think i only have one corner in my room. But a theres also a door there.


Would this qualify as a "real corner"? The otherside of the wall is oddly shaped. It curves inward if that makes any sense. So no corner there. And the front of the room is 3 windows that are protruding out(Where my system is in front of). I forgot what that design is called.


EDIT- Ah, bow and bay windows .


It looks kinda like this pic except i have no base to rest anything on and its not that deep. But you get the idea.












So yeah, one corner? I guess thats a good thing right? Nowhere for bass to buildup except the one corner.

Was thinking of putting a bass trap there. This specifically-

http://www.atsacoustics.com/corner-bass-trap-b.html


----------



## myfipie

Quote:

Shouldn't i buy bass traps to handle that? I was gonna go for solid back. No?
You can but we actually make our panels with a spacer built into the back. It is always recommend to have some space.


----------



## yacht422

local host, this one is for you.

it has been recommended that one place a thin covering of craft paper over rfg when used on first reflection or corner traps etc. the question is: what effect would the substitution of wire(as opposed to plastic) screening have? that is, standard home screen door screening being used as replacement for the kraft paper. is there added diffusion? would there be a negative effect as it relates to the reason for the kraft in the first place?

and, no, i cannot measure - lack the tools, and i am not certain at my age i'd ever be able to learn how.









thx

walt


----------



## yacht422

why are most, if not all of the commercially available sound devices manufactured to a 2' X 4' size??

for first reflection points, in a theater having two or more rows, it seems to me that a 4' X 4' would provide better coverage.

that said, given the comments of local host [et.al.] , I question whether absorbtion for the first row is all that really is needed, given that the distance (and therefore decay time) to the second row would render the treatments for the second row reflections "moot"? therefore, a 2' X 4' size would be correct, and a larger size might 'over-absorb'!

Eh?

Walt


----------



## yacht422

final question.

i am 'hanging' a strip of the pink stuff under my screen. (12' X 18" [std roll])

is it best to put the kraft side facing into the room or the wall?

speakers are 36" into the room, , not flush mounted.

walt


----------



## localhost127

Quote:

Originally Posted by *yacht422* 
it has been recommended that one place a thin covering of craft paper over rfg when used on first reflection or corner traps etc.
who recommends this?


for broadband panels at early reflection points (for specular energy) - adding kraft paper or any type of reflective material will reflect HF content, and as such, defeats the purpose.


regarding corner bass traps, it is ok and sometimes a design requirement to reflect some HF specular content back into the room - as the corner traps are merely for LF modal issues and with enough broadband 'bass' traps, can easily over-absorb the specular region as well. so sometimes a reflective face is added to address this (which will reflect some specular content back into the room, but will not impact (at least not negatively) the LF absorption).


----------



## yacht422

i lied! this is the last ??

has anyone used the black cloth marketed as "weed preventing underlayment for gardens" as a covering for rfg?

it is WAY cheaper than GOM and actually more porous.(the famous 'blow test')

the only color is, of course, black, but, it is cheaper.

so , any comments regarding pros/cons/?

thx

walt


----------



## localhost127

Quote:

Originally Posted by *yacht422* 
why are most, if not all of the commercially available sound devices manufactured to a 2' X 4' size??
2'x4' is a typical size that the batts of insulation (mineral wool, rigid fibgerglass, etc) are manufactured in.

Quote:

Originally Posted by *yacht422* 
or first reflection points, in a theater having two or more rows, it seems to me that a 4' X 4' would provide better coverage.
add coverage as necessary.

Quote:

Originally Posted by *yacht422* 
I question whether absorbtion for the first row is all that really is needed, given that the distance (and therefore decay time) to the second row would render the treatments for the second row reflections "moot"? therefore, a 2' X 4' size would be correct, and a larger size might 'over-absorb'!

Eh?

Walt
the same issues at the front row will be present at the second row.

if one is attenuating early reflections, then they need to be attenuated for any and all listening positions (seats, rows, etc) as required by the user.


----------



## yacht422

Quote:

Originally Posted by *localhost127* 
who recommends this?
Quote:

Originally Posted by *localhost127* 
i'll get back to you - i am reasonably certain i have read posts here that recommends either: 1)face the f/g with kraft, or 2) if using duct board, placing the reflective surface facing the room, or, 3) applying a 3mil covering of mylar over the raw rfg, again , facing into the room.


for broadband panels at early reflection points (for specular energy) - adding kraft paper or any type of reflective material will reflect HF content, and as such, defeats the purpose.


regarding corner bass traps, it is ok and sometimes a design requirement to reflect some HF specular content back into the room - as the corner traps are merely for LF modal issues and with enough broadband 'bass' traps, can easily over-absorb the specular region as well. so sometimes a reflective face is added to address this (which will reflect some specular content back into the room, but will not impact (at least not negatively) the LF absorption).


----------



## localhost127

broadband absorption panels to attenuate early reflections (if that is what you wish to do) - the panel needs to absorb/attenuate the entire specular reflection. as such, the fabric needs to be acoustically transparent and *not* include a reflective outer membrane (kraft paper).


for corner bass traps, it really doesn't matter. it's broadband absorption so it will absorb (depending on thickness, material, etc) the LF bass wavelengths, but it will alway continue to absorb throughout the specular region as well. since this sometimes results in too dead of a room (too quick decay times), some install a reflective membrane on the outside of the corner bass traps to reflect some HF energy back into the room. you are allowed to do this as long as the corner trap is not a geometric reflection point of early reflection energy.


----------



## myfipie




> Quote:
> Originally Posted by *localhost127* /forum/post/20857694
> 
> 
> who recommends this?
> 
> 
> for broadband panels at early reflection points (for specular energy) - adding kraft paper or any type of reflective material will reflect HF content, and as such, defeats the purpose.
> 
> 
> regarding corner bass traps, it is ok and sometimes a design requirement to reflect some HF specular content back into the room - as the corner traps are merely for LF modal issues and with enough broadband 'bass' traps, can easily over-absorb the specular region as well. so sometimes a reflective face is added to address this (which will reflect some specular content back into the room, but will not impact (at least not negatively) the LF absorption).



Actually, also if done right the limp membrane (covering the front) can increase the low end absorption.


----------



## yacht422




> Quote:
> Originally Posted by *myfipie* /forum/post/20858028
> 
> Actually, also if done right the limp membrane (covering the front) can increase the low end absorption.




by limp membrane, do you mean 3 mil poly? (per dennis' recommendation)

and is this covering the rfg at 1st reflection?

limp, as in hanging loose(not glued)

there is a lot of room here for individual interpretation

can you elaborate?]

thx

walt


----------



## myfipie




> Quote:
> Originally Posted by *yacht422* /forum/post/20870648
> 
> 
> [/color]
> 
> by limp membrane, do you mean 3 mil poly? (per dennis' recommendation)
> 
> and is this covering the rfg at 1st reflection?
> 
> limp, as in hanging loose(not glued)
> 
> there is a lot of room here for individual interpretation
> 
> can you elaborate?]
> 
> thx
> 
> walt



As in something like FRK on the fronts. You though do NOT want to use them in the first reflection (I call them early reflection points) as they will reflect high end which is what you don't want there.


----------



## longhorn055

Hello everybody, I'm new to this side of the forum (I didn't used to realize how important room treatment was). I've been doing a lot of reading in this thread, realtraps and GIK websites, etc.


I have a rather small home theater, dimensions and equipment:

13' long x 10' wide x 9' tall

Aperion Verus Grand towers and center

Hsu VTF3.4 sub

polk monitor 30 sorrounds

Denon AVR1610


After much reading, and given that I have some spare lumber to make the frames (DIY), this is my plan so far:

4 straddled bass traps, one per corner, OC705 DRK 4"x4'x2'

3 mid and high freq absorption at 1st reflection, side walls and ceiling, OC703 4"x4'x2'


I've attached a diagram


If I can receive comments regarding this plan that would be greatly appreciated!


----------



## localhost127




> Quote:
> Originally Posted by *longhorn055* /forum/post/20907237
> 
> 
> Hello everybody, I'm new to this side of the forum (I didn't used to realize how important room treatment was). I've been doing a lot of reading in this thread, realtraps and GIK websites, etc.
> 
> 
> I have a rather small home theater, dimensions and equipment:
> 
> 13' long x 10' wide x 9' tall
> 
> Aperion Verus Grand towers and center
> 
> Hsu VTF3.4 sub
> 
> polk monitor 30 sorrounds
> 
> Denon AVR1610
> 
> 
> After much reading, and given that I have some spare lumber to make the frames (DIY), this is my plan so far:
> 
> 4 straddled bass traps, one per corner, OC705 DRK 4"x4'x2'
> 
> 3 mid and high freq absorption at 1st reflection, side walls and ceiling, OC703 4"x4'x2'
> 
> 
> I've attached a diagram
> 
> 
> If I can receive comments regarding this plan that would be greatly appreciated!



sounds like a great start


although 4" of porous material is not a very effective bass trap...if you have the real estate, straddle the 4" panels horizontally (48" wide x 24" height) and stack to the ceiling - they will be far more effective.


or, if you do not have any real estate constraints in the corners - build your porous bass traps out of cheap pink fluffy insulation. if you have the space for very thick traps, this will be the most effective (and cheapest) option.


----------



## longhorn055




> Quote:
> Originally Posted by *localhost127* /forum/post/20908283
> 
> 
> sounds like a great start
> 
> 
> although 4" of porous material is not a very effective bass trap...if you have the real estate, straddle the 4" panels horizontally (48" wide x 24" height) and stack to the ceiling - they will be far more effective.
> 
> 
> or, if you do not have any real estate constraints in the corners - build your porous bass traps out of cheap pink fluffy insulation. if you have the space for very thick traps, this will be the most effective (and cheapest) option.



Thanks for your comments localhost! I do have very constrained real estate. I do have 2 doors very close to two of the corners, so a very wide trap would block them. Pictures attached might give a better idea.


So when you say "4" of porous material is not a very effective bass trap" do you mean there's other kind of material that would be more effective? I thought this is what most people used for bass traps, other than the "super chunks", and that OC705 or 703 or similar was the norm... if you mean 4" thickness is not enough, I can add thickness since I will construct them...


What is your recommendation considering the above?


----------



## nathan_h




> Quote:
> Originally Posted by *longhorn055* /forum/post/20908413
> 
> 
> Thanks for your comments localhost! I do have very constrained real estate. I do have 2 doors very close to two of the corners, so a very wide trap would block them. Pictures attached might give a better idea.
> 
> 
> So when you say "4" of porous material is not a very effective bass trap" do you mean there's other kind of material that would be more effective? I thought this is what most people used for bass traps, other than the "super chunks", and that OC705 or 703 or similar was the norm... if you mean 4" thickness is not enough, I can add thickness since I will construct them...
> 
> 
> What is your recommendation considering the above?



I think your plan looks like a great way to improve the sound in that room. I would recommend hanging some OC on the back wall behind the couch at ear level to reduce front - back echo reflections. Thicker is better but even 2" stuff would help.


----------



## Roger Dressler

Here's a way to improve the sound in your room for free.


1) Rotate the surrounds 90-degrees so they fire across the sofa. That will help the further listeners hear both speakers better, and it will improve the spatial effect. It will also improve the frequency response.


2) Move the sofa 2' forward of the rear wall. That will do more to tame the bass than any "trap" you can fit inside the room.


I agree that a rear wall absorber is a good idea. Probably the first one you should install. No need to make them to try the effect -- just put a large pillow back there and see what happens.


The side wall first-reflection panels may help especially because your speakers are really close to the walls. The ceiling absorber is the least of your worries, IMHO.


----------



## localhost127




> Quote:
> Originally Posted by *longhorn055* /forum/post/20908413
> 
> 
> So when you say "4" of porous material is not a very effective bass trap" do you mean there's other kind of material that would be more effective? I thought this is what most people used for bass traps, other than the "super chunks", and that OC705 or 703 or similar was the norm... if you mean 4" thickness is not enough, I can add thickness since I will construct them...



it's not only the material, but the spacing from the boundary. porous insulation is a velocity-based absorber. as such, it needs to be placed at areas of high particle velocity in order to be most effective (wavelength passes through porous material, and kinetic energy is converted into heat). velocity is at a maximum at 1/4wavelength of a particular frequency. at the boundary (wall), velocity goes to zero and pressure maximizes. your ears are sensitive to pressure but porous insulation is not. this is why thin bass traps (or traps placed right against a boundary) are not effective.


as one builds deeper porous absorbers (to space the material towards an area of high particle velocity where the trap will be most effective), one will want to use a material with lower gas-flow-resistivity (eg, pink fluffy). unfortunately, with your real estate constraints, your best bet will likely be to use the denser (higher GFR) material such as OC703 or OC705.


for your sidewall panels, 4" OC703 will be sufficient. specular reflections are higher in frequency and as such, the wavelengths are much smaller. porous insulation is extremely useful for attenuating specular reflections, it's just the low-freq (modal) issues where real estate constraints can quickly come into play.


Roger's comment about not sitting directly against the rear wall is a good start. if you can build a 6" OC703 panel (and possibly do 2-4" air-gap), that will address a lot of comb-filtering issues off of the rear wall.


----------



## longhorn055




> Quote:
> Originally Posted by *nathan_h* /forum/post/20908519
> 
> 
> I think your plan looks like a great way to improve the sound in that room. I would recommend hanging some OC on the back wall behind the couch at ear level to reduce front - back echo reflections. Thicker is better but even 2" stuff would help.





> Quote:
> Originally Posted by *Roger Dressler* /forum/post/20908751
> 
> 
> 
> 1) Rotate the surrounds 90-degrees so they fire across the sofa. That will help the further listeners hear both speakers better, and it will improve the spatial effect. It will also improve the frequency response.
> 
> 
> 2) Move the sofa 2' forward of the rear wall. That will do more to tame the bass than any "trap" you can fit inside the room.
> 
> 
> I agree that a rear wall absorber is a good idea. Probably the first one you should install. No need to make them to try the effect -- just put a large pillow back there and see what happens.



Nathan, Roger, thanks for the advice, I will move the chairs forward check out the difference tonight (I'll be able to know for sure later this week when I receive the sound card I ordered for REW measurements). I'll also plan on 2 6"x4'x2' (+2" air gap) on the rear wall.


Regarding the sorrounds, they are 90 deg., facing the sofa (sorry for the terrible quality pics, had to use my phone because my camera is broken







)


> Quote:
> Originally Posted by *localhost127* /forum/post/20909010
> 
> 
> it's not only the material, but the spacing from the boundary. porous insulation is a velocity-based absorber. as such, it needs to be placed at areas of high particle velocity in order to be most effective (wavelength passes through porous material, and kinetic energy is converted into heat). velocity is at a maximum at 1/4wavelength of a particular frequency. at the boundary (wall), velocity goes to zero and pressure maximizes. your ears are sensitive to pressure but porous insulation is not. this is why thin bass traps (or traps placed right against a boundary) are not effective.



hey localhost, I think I understand what you're saying here, but with the bass traps being straddled on the corner, that means there's an air gap of up to 13", correct?


----------



## localhost127




> Quote:
> Originally Posted by *longhorn055* /forum/post/20909224
> 
> 
> hey localhost, I think I understand what you're saying here, but with the bass traps being straddled on the corner, that means there's an air gap of up to 13", correct?



correct. and if you were in a position to straddle the panels in the corner horizontally (48" wide), the insulation would be spaced even further from the boundary and LF absorption coefficient would increase.


----------



## longhorn055




> Quote:
> Originally Posted by *localhost127* /forum/post/20909259
> 
> 
> correct. and if you were in a position to straddle the panels in the corner horizontally (48" wide), the insulation would be spaced even further from the boundary and LF absorption coefficient would increase.



ok I see your point now.


thank you all for your invaluable input. I'll report back when I get everything installed!


----------



## myfipie




> Quote:
> Originally Posted by *localhost127* /forum/post/20908283
> 
> 
> sounds like a great start
> 
> 
> although 4" of porous material is not a very effective bass trap...if you have the real estate, straddle the 4" panels horizontally (48" wide x 24" height) and stack to the ceiling - they will be far more effective.
> 
> 
> or, if you do not have any real estate constraints in the corners - build your porous bass traps out of cheap pink fluffy insulation. if you have the space for very thick traps, this will be the most effective (and cheapest) option.



I am not disagreeing with you but only pointing out that yes you are right straddling horizontally will work better (we actually recommend it), but if you are only going to put in 4 traps into a room you are better to cover more of the corner area with them vertical. Basically covering 4" in twice as much corner (vertically) area will gain you better results over half as much (horizontally).


----------



## localhost127




> Quote:
> Originally Posted by *myfipie* /forum/post/20911534
> 
> 
> I am not disagreeing with you but only pointing out that yes you are right straddling horizontally will work better (we actually recommend it), but if you are only going to put in 4 traps into a room you are better to cover more of the corner area with them vertical. Basically covering 4" in twice as much corner (vertically) area will gain you better results over half as much (horizontally).



+1

surface area is key.


----------



## longhorn055




> Quote:
> Originally Posted by *myfipie* /forum/post/20911534
> 
> 
> I am not disagreeing with you but only pointing out that yes you are right straddling horizontally will work better (we actually recommend it), but if you are only going to put in 4 traps into a room you are better to cover more of the corner area with them vertical. Basically covering 4" in twice as much corner (vertically) area will gain you better results over half as much (horizontally).





> Quote:
> Originally Posted by *localhost127* /forum/post/20911623
> 
> 
> +1
> 
> surface area is key.



Yeah, I just got enough 705 FRK to have 7 feet tall corner bass traps in front(4'+3' sections), 5 feet tall in the back (4'+1' sections) (the upper corner of the front wall is at an angle so I can't do the full 8 or 9 feet height).


----------



## longhorn055

Does anybody know if the GOM 701 (or any other fabric) can be painted on, probably with ink, while maintaining its acoustical properties?


My wife happens to be an artist, and she has happily agreed to share her artistic skills...


----------



## erkq




> Quote:
> Originally Posted by *longhorn055* /forum/post/20913662
> 
> 
> Does anybody know if the GOM 701 (or any other fabric) can be painted on, probably with ink, while maintaining its acoustical properties?
> 
> 
> My wife happens to be an artist, and she has happily agreed to share her artistic skills...



There are paintable AT fabrics, but the ones I know of require high pressure spray application. Can she air-brush?


----------



## longhorn055




> Quote:
> Originally Posted by *erkq* /forum/post/20913762
> 
> 
> There are paintable AT fabrics, but the ones I know of require high pressure spray application. Can she air-brush?



Yes air brush is a possibility.. not what I envisioned originally but might be an option..


----------



## localhost127




> Quote:
> Originally Posted by *longhorn055* /forum/post/20913412
> 
> 
> Yeah, I just got enough 705 FRK to have 7 feet tall corner bass traps in front(4'+3' sections), 5 feet tall in the back (4'+1' sections) (the upper corner of the front wall is at an angle so I can't do the full 8 or 9 feet height).



wonderful









you may want to peel a layer of FRK off of the middle and back layers of the traps, and keep FRK on the outer face only. however, and panel used for specular reflections (side walls, ceiling, rear wall, etc) should not have the reflective layer of FRK installed (will defeat the purpose of the panel).


you'll have to be careful regarding the rear corner (vertical) traps as well - as if there is a layer of FRK present, it may reflect some specular reflections back to the listening position.


do you have measurement gear?


----------



## longhorn055




> Quote:
> Originally Posted by *localhost127* /forum/post/20914112
> 
> 
> wonderful
> 
> 
> 
> 
> 
> 
> 
> 
> 
> you may want to peel a layer of FRK off of the middle and back layers of the traps, and keep FRK on the outer face only. however, and panel used for specular reflections (side walls, ceiling, rear wall, etc) should not have the reflective layer of FRK installed (will defeat the purpose of the panel).
> 
> 
> you'll have to be careful regarding the rear corner (vertical) traps as well - as if there is a layer of FRK present, it may reflect some specular reflections back to the listening position.
> 
> 
> do you have measurement gear?



Yes I did get half of the 705 and all of tge 703 w/o FRK


I hadnt think about the frk on the rear traps, thats a very good point! So i guess ill remove the foil from the rear traps


I have the RS spl meter abd usb soundcard for REW measurements is on the way!


----------



## localhost127




> Quote:
> Originally Posted by *longhorn055* /forum/post/20914436
> 
> 
> Yes I did get half of the 705 and all of tge 703 w/o FRK
> 
> 
> I hadnt think about the frk on the rear traps, thats a very good point! So i guess ill remove the foil from the rear traps
> 
> 
> I have the RS spl meter abd usb soundcard for REW measurements is on the way!



ok - when you're ready, you'll be focusing on the waterfall plot for low-freq modal issues (0-300hz). it will display the frequency response in the modal region as well as the time-domain (z-axis) that will detail you the modal ringing (LF decay). the peaks/nulls are obviously an issue, but it's the LF decay that is truly detrimental and creates that muddy mess of all of the bass notes running together. your bass traps and their effectiveness will be measured with the waterfall plot.


above the modal region is the specular region where the sound can be modeled like light (ray-traced). you'll use the Envelope Time Curve (ETC) response; this will detail to you how energy arrives at the listening position (in gain (dB)) with respect to time (since speed of sound in your room is a constant - reflections arrive at the listening position with respect to time based on their total distance traveled). it will detail to you the first burst of energy as a straight vector from the acoustic center to your listening position (since that is the shortest path), and then specific reflections and finally how the specular energy decays within the room.


one normally chooses an ISD-gap (inter signal delay) which essentially is a length in time of which no reflections impede the listening position. this psycho acoustically dictates to your brain how large the room is. if you were to listen to music in a small bedroom, the distance of the walls is relatively close - as such, the reflections arrive very early in time after the direct signal. in a larger room, those reflections travel much further and as such, take longer to reach the listening position after the direct signal. this length in time dictates to the brain how 'large' the room is. you are artificially increasing the size of your room by delaying (via absorption) how late in time it takes for the first reflection to reach your ears after the original signal. the brain doesn't process an early reflection as being a separate reflection within 20ms (+/-, there are more advanced issues here - but keeping it simple). so, the general goal is to measure with the ETC which will detail to you how the specular energy (and reflections) impede the listening position. you will see all of these early reflections and can then hunt them down and kill them with absorption. generally speaking (keeping things simplified), you'll want to destroy all reflections within 20ms of the original signal to -15 or -20dB in gain (attenuated).


here is an example of an ETC with an untreated room and with the reflections attenuated:



http://imgur.com/6RbQ4.jpg%5B/IMG%5D



lastly, one really is only concerned with the frequency domain for modal issues (low-freq). any frequency response issues in the specular region (where energy behaves/can be modeled like light) is addressed in the time-domain with the ETC response. that is because comb-filtering response is due to the summation of these reflections with the original signal at the listening position - combining in-phase and out of phase to cause the peaks and nulls in the freq response. once you attenuate the early reflections (any energy within 20ms above -20dB of the original signal), this should cure your comb-filtering response in the frequency domain.


the side-walls, ceiling, rear wall, floor first-reflection points are easily found with the mirror-trick which im sure you're already aware of ... but the ETC response within Room EQ Wizard will eliminate the guesswork and tell you very specifically whether any energy is still impeding the listening position within this 20ms window. you'll find out if your broadband absorption panels are truly attenuating the reflection to the gain you wish (eg., -15 to -20dB). you'll also discover whether any energy (reflections) is impeding the listening position by other non-obvious objects in the room - such as a coffee table or edge diffraction off of another device within the room.


many on this forum blindly install thin absorption (eg., 1" oc703) and think that that is satisfactory to attenuating early reflections - which is simply not true. so kudos to you for doing it proper the first time around and attacking with 4" OC703. the bulk of the energy within the specular reflections is in the low-mid range and as such, absorption needs to be sufficient to attenuate this. this is also the reason why when using the mirror-trick, one should look to view the acoustic center of the speaker in the mirror, vs just the tweeter.


----------



## erkq




> Quote:
> Originally Posted by *longhorn055* /forum/post/20913826
> 
> 
> Yes air brush is a possibility.. not what I envisioned originally but might be an option..



Great... now I can't find it. I'll get back to you if I can locate it.


----------



## pepar

Excellent post, localhost127!! Bookmarked!


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *longhorn055* /forum/post/20913826
> 
> 
> Yes air brush is a possibility.. not what I envisioned originally but might be an option..



you can also use the ETC to measure whether your 'painted' fabrics are still acoustically transparent or whether they are reflecting some energy. this will remove the guesswork, but i am not an expert on types of paint, airbrushed, etc or any of the painted fabrics.


you may wish to reference this thread:
http://www.avsforum.com/avs-vb/showthread.php?t=1316623


----------



## longhorn055

Many thanks localhost! bookmarked your post also!


Now not only I understand what tests to run, but the reason why


I can't wait to get some waterfall and ETC plots!


----------



## longhorn055

Quote:

Originally Posted by *erkq* 
Great... now I can't find it. I'll get back to you if I can locate it.
ok erkq that would be good, thank you


For now I think I'll stop at Joanns and get some samples. I did order some samples of the GOM701 also... but I have the feeling that polyester wont take the paint very well as cotton does... so I'll do the air test on them and a real test when I get the equipment I need to run the REW as localhost suggested


----------



## myfipie

Quote:

Originally Posted by *longhorn055* 
ok erkq that would be good, thank you


For now I think I'll stop at Joanns and get some samples. I did order some samples of the GOM701 also... but I have the feeling that polyester wont take the paint very well as cotton does... so I'll do the air test on them and a real test when I get the equipment I need to run the REW as localhost suggested
IME you can not paint the fabric as it will fill in the open areas that lets sound in, which you do not want. The only way I know is to use Dye Sublimation printing. Here is a print I like to show off that I had my guys make for me!

















[/IMG]


----------



## localhost127

Quote:

Originally Posted by *longhorn055* 
I can't wait to get some waterfall and ETC plots!
remember to measure ETC *one speaker at a time!*


you are interested in finding the reflection points for each speaker --- as using both speakers at the same time, you will not be able to decypher which energy on the ETC corresponds to a reflection point from off-axis energy from which speaker.


you're interested in finding all early reflection points per speaker (eg., within that 20ms time window - and attenuating any you find). once all your work is done, you can then take a 'final' ETC with both speakers for a total specular response.


----------



## longhorn055

Quote:

Originally Posted by *myfipie* 
IME you can not paint the fabric as it will fill in the open areas that lets sound in, which you do not want. The only way I know is to use Dye Sublimation printing. Here is a print I like to show off that I had my guys make for me!

















[/IMG]
Thanks Glenn! that's a great looking print!


Your post got me thinking, that although paint might not be the way to go, ink might be (just like dye from a printer)... so I had my wife do a test. And while acrylic paint, gouache etc did fill the "pores" of the fabric, the ink did not. Fabric used was cotton, which might be important since it does absorb the ink (as opposed to polyester, I believe). The "inked" surface did pass the breath and light test, I think... I won't know for sure until I run ETC test...


----------



## longhorn055

Quote:

Originally Posted by *localhost127* 
remember to measure ETC *one speaker at a time!*


you are interested in finding the reflection points for each speaker --- as using both speakers at the same time, you will not be able to decypher which energy on the ETC corresponds to a reflection point from off-axis energy from which speaker.


you're interested in finding all early reflection points per speaker (eg., within that 20ms time window - and attenuating any you find). once all your work is done, you can then take a 'final' ETC with both speakers for a total specular response.
Yes, will do!


----------



## nosferatu2xlc

quick question , will placing acoustic panels above tv does any improvements ? i have 4 large panels behind the couch already .


thank you


----------



## MilesBFree

Hi,


Does anyone have a good alternative for GoM FR701 as an AT fabric? The wife and I are not wild about the colors and the texture, but the inspector wants proof that it is Class A fireproof, which the FR701 is so it is a safe choice. But I was hoping for some alternatives, so recommendations would be much appreciated!


----------



## localhost127




> Quote:
> Originally Posted by *MilesBFree* /forum/post/20947851
> 
> 
> Hi,
> 
> 
> Does anyone have a good alternative for GoM FR701 as an AT fabric? The wife and I are not wild about the colors and the texture, but the inspector wants proof that it is Class A fireproof, which the FR701 is so it is a safe choice. But I was hoping for some alternatives, so recommendations would be much appreciated!



i think quite a few of the online 'acoustic treatment' shops also sell their own fire-rated fabric, so you may wish to browse around their online stores.


----------



## pepar

Yeah, good luck. Class A rated _acoustically transparent_ cloth doesn't come in designer colors and patterns.


----------



## MilesBFree

Some alternatives to the GoM FR701 I have found so far:

*Knoll Textiles:* http://www.knoll.com/techdoc/KT_AcousticalFabrics.pdf 

Most of these that I looked at appear to be Class A fire rated. However, at $35 a linear yard and up I didn't look at very many.

*Dazian Expo / Exposure:* http://www.dazian.net/cgi-bin/page.p...=253&group_id= 

This is discontinued but came up in a search as certain colors still available. It is about $7.50 a yard.

*Hytex:* http://hytex.com/collections.html or http://www.fabricmatestore.com/c-30-...el-fabric.aspx 

Several of their lines are listed as AT.

*Koroseal:* http://korosealacoustics.com/finishes.php?opt=atf 

They have some interesting graphic patterns.

*Acoustone:* http://www.acoustonespeakercloth.com...RECH_CLOTH.asp 

They sell 3 different lines that would be suitable for the purpose, but the line they make for amplifier speaker covers (i.e.- a guitar amp) looks exactly like what you would expect for that purpose and might not look right for a whole wall treatment. It is not cheap either but one of their lines is comparable in price the the GoM and might offer different color choices.

*AcousTex:* http://www.acoustex.com/Colorcard_designer.html 

These look very similar in color and texture to the GoM FR701 line.

*Acoustimac:* http://www.acoustimac.com/index.php/...-the-yard.html 

It is listed as "DMD Acoustic Fabric", so I am not sure if the brand is DMD or if that is their own description. Since it looks like they are a store, I am guessing tha actual fabric is made by someone else.

*TK Living:* http://tk-living.com/fabrics/index.html 

No prices listed, and I have seem a few theaters they built and I am guessing it is a case of "if you have to ask, you can't afford it". Since they are a theater builder, I am guessing they are just reselling others' fabric.

*Acoustic Innovations:* http://acousticinnovations.com/acous...s/concertowall 

It looks like they may be more of a distributor and no make their own fabric, but I am emailing them to see what they offer.

*Soundproof Cow:* http://www.soundproofcow.com/acousti...ic-panels.html 

They probably resell other manufacturers' fabric, but I thought it was interesting that they print on it. I am not sure if that would affect the acoustic transparency, but it is an interesting idea so I thought I would include them here.

*Brejtfus:* http://www.brejtfus.com/fabrics.html 

Will custom dye the fabric. Looks like they likely use GoM FR701 as the basic fabric. Also will print on fabric.


I will continue to edit/add to this post as I find more.


----------



## localhost127

on porous absorption:

http://www.gearslutz.com/board/bass-...roperties.html 

http://www.gearslutz.com/board/6634314-post70.html


----------



## dragonleepenn

Does anyone have experience using roxul insulation for room tuning? And can same be used to make bass traps, Please if possible let me know i'm thinking of adding more traps in my room but have no knowledge on this material. Thanks!


----------



## localhost127




> Quote:
> Originally Posted by *dragonleepenn* /forum/post/20974065
> 
> 
> Does anyone have experience using roxul insulation for room tuning? And can same be used to make bass traps, Please if possible let me know i'm thinking of adding more traps in my room but have no knowledge on this material. Thanks!



the *flow resistivity* value of the insulation is the pertinent information you need to find.


bass traps made of porous insulation are velocity-based absorbers, and must be located at areas of high particle velocity in order to be highly effective.


i suggest reading the thread i had just posted, above:
http://www.gearslutz.com/board/bass-...roperties.html 


you can play around with the porous absorber calculator (input flow-resistivity, and modify insulation thickness + air-gap thickness).
http://www.whealy.com/acoustics/Porous.html 


you'll find that very thick porous traps (insulation+air-gap) of low gas-flow-resistivity material are highly effective at LF absorption. this is great news, as cheap, pink fluffy attic insulation with ~5000rayls/m will perform better and save on materials cost vs rigid fiberglass or equivalent mineral wool (eg, save the expensive rigid fiberglass (OC703) for broadband specular reflection absorbers, and use the cheap pink fluffy stuff for corner porous bass traps).


if you have real estate constraints and cannot make deep traps, then thinner traps of higher GFR material will probably work better for you. real estate is the defining constraint - as it will determine which material you should use.


----------



## FOH




> Quote:
> Originally Posted by *localhost127* /forum/post/20975440
> 
> 
> ......
> 
> 
> ...... _*real estate*_ is the defining constraint - as it will determine which material you should use.



Additionally, I think it's worth mentioning that from all the evidence I've seen, *real estate* is of significant importance in coverage as well. In addition to the very thick porous traps, some rigid stuff covering as much linear coverage as possible elsewhere in the space is also very beneficial.


localhost,

I greatly appreciate the links to the other conversations regarding these issues. A considerable amount of good stuff contained therein.



Thank you


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/20984983
> 
> 
> Additionally, I think it's worth mentioning that from all the evidence I've seen, *real estate* is of significant importance in coverage as well. In addition to the very thick porous traps, some rigid stuff covering as much linear coverage as possible elsewhere in the space is also very beneficial.



right. regardless of depth of traps, surface area (coverage) is important. and then the type of material to use (flow-resistivity) for the porous bass trap is determined by the real estate constraints regarding maximum thickness (insulation + air-gap) of the corner absorber.




> Quote:
> Originally Posted by *FOH* /forum/post/20984983
> 
> 
> localhost,
> 
> I greatly appreciate the links to the other conversations regarding these issues. A considerable amount of good stuff contained therein.
> 
> 
> 
> Thank you



thanks! most of it is from the folks at GS forums (sorry for cross-posting so much stuff from there) --- but information is information







- no sense reinventing the wheel.


self-made diffusers were not really around a few years ago. now, look how many are tackling their own designs (teach a man to fish....). maybe in a few more years, self-made pressure-based bass traps will be more common. hopefully i'll have some time (space) to start some attempts here soon.


have you seen AMFG SoundFlow?
http://soundflow.afmg.eu/


----------



## FOH




> Quote:
> have you seen AMFG SoundFlow?



No, ...interesting.


----------



## localhost127

another fun thursday read (specifically, post 24)
http://www.gearslutz.com/board/bass-...absorbers.html


----------



## localhost127

GE has had a great thread going on for quite some time...always good to read through progress, trial, errors, testing, etc..

http://www.gearslutz.com/board/bass-...rs-max-12.html


----------



## seigneur_rayden

I have a rectangular room 12 X 24 and would like to treat it for acoustic.

It will be a 7.2 configuration. Both subs will be in the front.

I was planning on buying JM 814 (OC 703 equivalent) in 2" thickness.


Since it comes in bundle of 9, I will have 18 panels as it is cheaper to get 2 bundles versus 1.


My initial vision/plan is to put

6 panels in front behind the screen and speakers.

2 panels in the back wall

2 on the ceiling in the front between speakers and listening position

3 on each side walls.

The 3 left are left for suggestion.


Will 2" be too much absorption for the side walls, rear wall and ceiling?


What do you guys think of this initial plan?


Thanks for the help.


I've been reading this thread and it is kinda long and so far I have not got a clear answer whether to go with 1" or 2" rigid board. JM 814 is the only thing I can get locally. Linacoustic is $452 for a roll










Some more info: the door is on the back side of the room, room is vanilla (screen, speakers, 5 seats and 2 people), single drywall with R-11 in the cavities.


Right now, every sound that produced in the room is so AMPLIFIED. When I speak, it is like I was speaking with a microphone. Fly buzzing sounds like a motor. I can hear every bit of little sound.


Is this what called "being live" as opposed to being "dead"?


I can't imagine how will loudspeakers sound if I put them while the room is amplifying the sound this much. I hope it makes sense.


----------



## nezff

 Attachment 223810 

these helped with my echo

30x15 room with angled ceilings.


----------



## stepyourgameup




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21007936
> 
> 
> 
> Will 2" be too much absorption for the side walls, rear wall and ceiling?
> No. 2" is good and if you can leave some space between the panel and the wall even better.


----------



## localhost127




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21007936
> 
> 
> Will 2" be too much absorption for the side walls, rear wall and ceiling?



for specular reflections, 4" OC703 w/ 2-4" air-gap. thin absorption will merely soak out HF content which has the least energy to begin with (hence, easiest to absorb) and allow the lower specular energy to persist.


this is independent of LF absorption ("bass trapping") - which is a different set of problems and different set of solutions.


----------



## seigneur_rayden




> Quote:
> Originally Posted by *stepyourgameup* /forum/post/21009254



Good to know that it is not too much.


> Quote:
> Originally Posted by *localhost127* /forum/post/21009305
> 
> 
> for specular reflections, 4" OC703 w/ 2-4" air-gap. thin absorption will merely soak out HF content which has the least energy to begin with (hence, easiest to absorb) and allow the lower specular energy to persist.
> 
> 
> this is independent of LF absorption ("bass trapping") - which is a different set of problems and different set of solutions.



Thanks for the reply. Are specular reflections the same thing as first reflections?

I may address the lower frequency with some small bass traps in the front corners.


----------



## localhost127




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21009728
> 
> 
> Thanks for the reply. Are specular reflections the same thing as first reflections?
> 
> I may address the lower frequency with some small bass traps in the front corners.



yes. specular energy can be modeled like light (rays) (angle of incidence = angle of reflection, just like how pool balls bounce around a billiards/pool table). this is why we find 'geometric reflection points'.


bear in mind this type of absorption should be applied _surgically_ .... not blindly and most certainly not covering entire walls/boundaries.


bass (LF) has wave-like properties...with porous insulation (LF absorption), we treat these issues in the corners of the room (remember, 12 corners in a rectangular room!).


rigid fiberglass (OC703) or mineral wool is good for reflection point panels (dense; high gas-flow-resistivity)...and their self-supporting structure by nature (OC703) makes them very easy to work with. OC703 doesn't even require a frame - you can just wrap fabric around it if you really wanted to...


LF absorption for bass/modal issues, very deep porous traps are required. but you're in luck - as the most effective porous bass trap is one made with the cheapest material (pink fluffy attic insulation - very thick traps, loosely filled (not compressed!). you can build corner superchunks out of the cheap pink stuff and save the more expensive OC703 for reflection point broadband absorption.


you'll see many recommend OC703/mineral wool for corner bass traps but this is no where near as effective as pink fluffy.


----------



## localhost127

by the way, if you are into measuring so that you are not blindly applying your treatments, there exists a very specific tool within the free measuring suite 'Room EQ Wizard' that you can use to detail all information with regards to specular energy...


eg,

- that your broadband panels are placed properly to attenuate the specular reflection across the entire listening position

- that your broadband panels are effective at attenuating the specular reflection (absorbing) to a sufficient gain (eg, -20dB)

- if you are seeing other early specular energy at the listening position off of a surface which may not be so obvious (you can hunt it down and find out where it is incident from)


if you're interested in this i can go on further..


----------



## seigneur_rayden




> Quote:
> Originally Posted by *localhost127* /forum/post/21010285
> 
> 
> yes. .....
> 
> 
> bear in mind this type of absorption should be applied _surgically_ .... not blindly and most certainly not covering entire walls/boundaries.
> 
> 
> bass (LF) has wave-like properties...with porous insulation (LF absorption), we treat these issues in the corners of the room (remember, 12 corners in a rectangular room!).
> 
> 
> 
> LF absorption for bass/modal issues, very deep porous traps are required. but you're in luck - as the most effective porous bass trap is one made with the cheapest material (pink fluffy attic insulation - *very thick traps, loosely filled (not compressed!).* you can build corner superchunks out of the cheap pink stuff and save the more expensive OC703 for reflection point broadband absorption.
> 
> 
> you'll see many recommend OC703/mineral wool for corner bass traps but this is no where near as effective as pink fluffy.



Thanks for the recommendation. I think I read somewhere that the fluffy insulation had to be left in their bag when used for bass trapping. Is loosely filled a better method?


> Quote:
> Originally Posted by *localhost127* /forum/post/21010335
> 
> 
> by the way, if you are into measuring so that you are not blindly applying your treatments, there exists a very specific tool within the free measuring suite 'Room EQ Wizard' that you can use to detail all information with regards to specular energy...
> 
> 
> eg,
> 
> - that your broadband panels are placed properly to attenuate the specular reflection across the entire listening position
> 
> - that your broadband panels are effective at attenuating the specular reflection (absorbing) to a sufficient gain (eg, -20dB)
> 
> - if you are seeing other early specular energy at the listening position off of a surface which may not be so obvious (you can hunt it down and find out where it is incident from)
> 
> 
> if you're interested in this i can go on further..



Yes I am definitely interested. I don't want to go blindly. So please go on further and thanks for your replies.


----------



## localhost127




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21010411
> 
> 
> Thanks for the recommendation. I think I read somewhere that the fluffy insulation had to be left in their bag when used for bass trapping. Is loosely filled a better method?



correct. when you purchase it in the per-compressed rolls, it is highly compressed (mostly to save real estate for shipping and retail). to be effective, it needs to be uncompressed.

http://www.whealy.com/acoustics/Porous.html 


you can make corner superchunk traps out of pink fluffy, but you will need horizontal support. otherwise, the overall weight of the pink fluffy will start to compress the layers at the bottom. so adding some base supports every few feet would be beneficial. you can keep the insulation exposed, use a layer of chicken wire and cover it with fabric. corner bass traps are broadband, so they inadvertently absorb above the modal region - which can quickly create a dead room if you have lots of bass traps. for this, you can apply a plastic, reflective barrier on the outside face of the trap such that some HF specular content is reflected back into the room.




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21010411
> 
> 
> Yes I am definitely interested. I don't want to go blindly. So please go on further and thanks for your replies.



you can download Room EQ Wizard to get started.

do you have a mic, pre-amp, etc?


----------



## seigneur_rayden




> Quote:
> Originally Posted by *localhost127* /forum/post/21011575
> 
> 
> correct. when you purchase it in the per-compressed rolls, it is highly compressed (mostly to save real estate for shipping and retail). to be effective, it needs to be uncompressed.
> 
> http://www.whealy.com/acoustics/Porous.html
> 
> 
> you can make corner superchunk traps out of pink fluffy, but you will need horizontal support. otherwise, the overall weight of the pink fluffy will start to compress the layers at the bottom. so adding some base supports every few feet would be beneficial. you can keep the insulation exposed, use a layer of chicken wire and cover it with fabric. corner bass traps are broadband, so they inadvertently absorb above the modal region - which can quickly create a dead room if you have lots of bass traps. for this, you can apply a plastic, reflective barrier on the outside face of the trap such that some HF specular content is reflected back into the room.
> 
> 
> you can download Room EQ Wizard to get started.
> 
> do you have a mic, pre-amp, etc?



I have a mic that came with the AVR for calibration. I don't have a pre-amp though. I only have an AVR.

Thanks for the advice on the bass trap. I will follow that. My initial plan is to have only 2 bass traps in the front corner.

Downloaded the file from the link above, playing with it right now.


----------



## localhost127




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21014262
> 
> 
> I have a mic that came with the AVR for calibration. I don't have a pre-amp though. I only have an AVR.
> 
> Thanks for the advice on the bass trap. I will follow that.



flow-resistivity is what's important regarding porous absorption.

porous insulation is a velocity-based absorber (not a pressure-based!) meaning, it must be placed at areas of high particle velocity to be effective (as the wavefront is forced through the insulation, kinetic energy is converted into heat). if there is little particle velocity, then little energy is being absorbed...


particle velocity is at a maximum at 1/4wavelength of a frequency (and pressure is zero), and velocity is ZERO at the boundary/wall (where pressure is a maximum) - this is why porous bass traps need to be very thick and spaced far from the boundary.


however, as you create thicker and thicker traps, you'll want to use a material with lower flow-resistivity.


pink fluffy is around 5000rayls/M - OC703 is around 16,500 if i recall correctly.


there are many who insist on OC703/OC705 for corner bass traps, but that assumption isn't always correct. pink fluffy will outperform at lower frequencies (which becomes difficult with porous absorption) and will be much, MUCH cheaper in materials cost.


OC703 is easier to work with (it's rigid and self supporting), so that is it's primary advantage...but use the cheap pink fluffy for corner traps and save the expensive OC703 for reflection absorbers.



> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21014262
> 
> 
> I will follow that. My initial plan is to have only 2 bass traps in the front corner.



attack as many corners as possible - there are 12 in a rectangular room. *good coverage (sq area) is just as crucial as having effective traps!!*


OC703 (16,500 rayls/m)


http://imgur.com/u1QVB.png%5B/IMG%5D



pink fluffy (5000 rayls/m)


http://imgur.com/I5LcQ.png%5B/IMG%5D



providing the air-gap spaces the insulation _further_ away from the boundary towards areas of higher particle velocity, where the absorber will be more effective.


----------



## seigneur_rayden




> Quote:
> Originally Posted by *localhost127* /forum/post/21015166
> 
> 
> flow-resistivity is what's important regarding porous absorption.
> 
> porous insulation is a velocity-based absorber (not a pressure-based!) meaning, it must be placed at areas of high particle velocity to be effective (as the wavefront is forced through the insulation, kinetic energy is converted into heat). if there is little particle velocity, then little energy is being absorbed...
> 
> 
> particle velocity is at a maximum at 1/4wavelength of a frequency (and pressure is zero), and velocity is ZERO at the boundary/wall (where pressure is a maximum) - this is why porous bass traps need to be very thick and spaced far from the boundary.
> 
> 
> however, as you create thicker and thicker traps, you'll want to use a material with lower flow-resistivity.
> 
> 
> pink fluffy is around 5000rayls/M - OC703 is around 16,500 if i recall correctly.
> 
> 
> there are many who insist on OC703/OC705 for corner bass traps, but that assumption isn't always correct. pink fluffy will outperform at lower frequencies (which becomes difficult with porous absorption) and will be much, MUCH cheaper in materials cost.
> 
> 
> OC703 is easier to work with (it's rigid and self supporting), so that is it's primary advantage...but use the cheap pink fluffy for corner traps and save the expensive OC703 for reflection absorbers.
> 
> 
> 
> 
> attack as many corners as possible - there are 12 in a rectangular room. *good coverage (sq area) is just as crucial as having effective traps!!*
> 
> 
> 
> providing the air-gap spaces the insulation _further_ away from the boundary towards areas of higher particle velocity, where the absorber will be more effective.



Wow, thanks very much localhost127 for the time you took to enlighten me on the subject and on your suggestions. I really appreciate it. As a result of your replies, I feel like I increased my knowledge in acoustic.


I will work on the bass traps and play with them starting next week. I will let you know how it goes.

I am thinking of a hybrid bass trap where I will put 2 of the extra rigid panel in the corner in a 45 deg angle and fill the space behind with pink fluffy just for the front. Then the rest of the traps, I will use the chicken wire with pink fluffy as you suggested. I don't find that hard to work with the fluffy stuff.

I'm all about being cheap and efficient.


Now I just need to find the proper fabric. I was thinking of $4 Full size bed sheet from walmart.


----------



## FOH

Nice illustration...


So if we assume this is correct (and there's no reason not to), fluffy is approx. 50% more effective at 20hz, nearly 100% more effective at 25hz, clearly over 100% more effective at 40hz, and again twice as effective on up to about 80hz. This is superb performance, even when compared to an already very good approach.


Question; the sim model states _Rigid Backed Porous Absorber_, is the rigid aspect referring to the boundary surface, such as a wall? Surely it's not intended literally, as a _rigid backed absorber_, ...right?


Question; any approach sandwiching of material densities/material types, provide any additional gains? I've read a significant amount over at GearSlutz, however some threads, (just as they do here) become overwhelmingly unwieldy. So,..break it down for us. Not to muddy the waters, but I've read no hard and fast rules, as every scenario is somewhat different. I'm referring to material thickness/density, gap size, boundary surface diaphragmatic disapation,..so in essence what's best for LF absorption in any one one..._depends_.


As always, thanks for your contributions


----------



## localhost127




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21015497
> 
> 
> I am thinking of a hybrid bass trap where I will put 2 of the extra rigid panel in the corner in a 45 deg angle and fill the space behind with pink fluffy just for the front. Then the rest of the traps, I will use the chicken wire with pink fluffy as you suggested. I don't find that hard to work with the fluffy stuff.
> 
> I'm all about being cheap and efficient.


*there is zero benefit to mixing acoustic impedance with regard to absorption*




> Quote:
> Originally Posted by *seigneur_rayden* /forum/post/21015497
> 
> 
> Now I just need to find the proper fabric. I was thinking of $4 Full size bed sheet from walmart.



with reflection point panels, the fabric needs to be breathable (acoustically transparent) - with bass traps it's less important as we're only concerned with low frequencies. check your local JoAnns fabric...or there are many online shops that sell acoustic treatments from which you can purchase fabric (since they stock good materials/colours/etc) - i would definitely recommend getting fire-treated fabric.


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/21015634
> 
> 
> Question; the sim model states _Rigid Backed Porous Absorber_, is the rigid aspect referring to the boundary surface, such as a wall? Surely it's not intended literally, as a _rigid backed absorber_, ...right?



correct -



> Quote:
> Originally Posted by *FOH* /forum/post/21015634
> 
> 
> Question; any approach sandwiching of material densities/material types, provide any additional gains? I've read a significant amount over at GearSlutz, however some threads, (just as they do here) become overwhelmingly unwieldy. So,..break it down for us. Not to muddy the waters, but I've read no hard and fast rules, as every scenario is somewhat different. I'm referring to material thickness/density, gap size, boundary surface diaphragmatic disapation,..so in essence what's best for LF absorption in any one one..._depends_.
> 
> 
> As always, thanks for your contributions



no advantage to mixing different materials with different acoustical impedance.


another good read:
http://downloads.bbc.co.uk/rd/pubs/reports/1982-04.pdf


----------



## Norman Varney

FOH- Yes, you can combine diaphragmatic and reactive technologies to achieve better broadband absorption, and with less space. As Localhost 127 has previously stated:


"porous insulation is a velocity-based absorber (not a pressure-based!) meaning, it must be placed at areas of high particle velocity to be effective (as the wavefront is forced through the insulation, kinetic energy is converted into heat). if there is little particle velocity, then little energy is being absorbed...


particle velocity is at a maximum at 1/4wavelength of a frequency (and pressure is zero), and velocity is ZERO at the boundary/wall (where pressure is a maximum) - this is why porous bass traps need to be very thick and spaced far from the boundary."


Combining the two can be very effective for broadband applications. If you were to fill the corners with 27" of "pink fluffy", you'll effectively absorb frequencies down to only 125Hz. (maximum particle velocity at material surface, 1/4 wavelength). Along with using up a lot of real state, you'll very likely over absorb your mid and high frequencies, and still leave the low frequencies unaddressed.


As you stated, it depends on the variables and every scenario is different. There are rules that can be applied to the scenario to achieve the desired results. The solution will be the right materials, in the right quantities, in the right locations.


----------



## localhost127




> Quote:
> Originally Posted by *Norman Varney* /forum/post/21016067
> 
> *Combining the two can be very effective for broadband applications. If you were to fill the corners with 27" of "pink fluffy", you'll effectively absorb frequencies down to only 125Hz.* (maximum particle velocity at material surface, 1/4 wavelength). Along with using up a lot of real state, you'll very likely over absorb your mid and high frequencies, and still leave the low frequencies unaddressed.



hello, Norman - you do not need to be at 1/4wavelength distances in order for absorption w/ porous insulation to take place - but moving towards 1/4wavelength will increase effectiveness of the absorber. but it by no means insist that no absorption is taking place (a common misconception).


i highly recommend reading this thread:
http://www.gearslutz.com/board/studi...q-4-avare.html 


it is a classic. some key points in there..


----------



## FOH




> Quote:
> Originally Posted by *Norman Varney* /forum/post/21016067
> 
> 
> FOH- Yes, you can combine diaphragmatic and reactive technologies to achieve better broadband absorption, and with less space. As Localhost 127 has previously stated:
> 
> 
> "porous insulation is a velocity-based absorber (not a pressure-based!) meaning, it must be placed at areas of high particle velocity to be effective (as the wavefront is forced through the insulation, kinetic energy is converted into heat). if there is little particle velocity, then little energy is being absorbed...
> 
> 
> particle velocity is at a maximum at 1/4wavelength of a frequency (and pressure is zero), and velocity is ZERO at the boundary/wall (where pressure is a maximum) - this is why porous bass traps need to be very thick and spaced far from the boundary."
> 
> 
> Combining the two can be very effective for broadband applications. If you were to fill the corners with 27" of "pink fluffy", you'll effectively absorb frequencies down to only 125Hz. (maximum particle velocity at material surface, 1/4 wavelength). Along with using up a lot of real state, you'll very likely over absorb your mid and high frequencies, and still leave the low frequencies unaddressed.
> 
> 
> As you stated, it depends on the variables and every scenario is different. There are rules that can be applied to the scenario to achieve the desired results. The solution will be the right materials, in the right quantities, in the right locations.



I believe you misunderstood. I'm aware of pressure based, and velocity based approaches,...however I was asking about mixing various gas flow resistivity approaches, "sandwich" style. Say, a 2" 703 faced Superchunk, filled behind with pink fluffy. Or multiple layers of firm/soft/firm/soft, etc...I'm merely thinking aloud.


Thanks


----------



## Norman Varney




> Quote:
> Originally Posted by *FOH* /forum/post/21016741
> 
> 
> I believe you misunderstood. I'm aware of pressure based, and velocity based approaches,...however I was asking about mixing various gas flow resistivity approaches, "sandwich" style. Say, a 2" 703 faced Superchunk, filled behind with pink fluffy. Or multiple layers of firm/soft/firm/soft, etc...I'm merely thinking aloud.
> 
> 
> Thanks



I see. Right, that would not be as effective as say rigid with soft behind, or soft/rigid/soft. As you know, it's a matter of getting the right compliant mass at the right location in the space.


----------



## seigneur_rayden




> Quote:
> Originally Posted by *localhost127* /forum/post/21015735
> 
> *there is zero benefit to mixing acoustic impedance with regard to absorption*
> 
> 
> 
> with reflection point panels, the fabric needs to be breathable (acoustically transparent) - with bass traps it's less important as we're only concerned with low frequencies. check your local JoAnns fabric...or there are many online shops that sell acoustic treatments from which you can purchase fabric (since they stock good materials/colours/etc) - i would definitely recommend getting fire-treated fabric.



Duly noted on not wasting the rigid board.

I know about the transparency of the fabric. The bed sheet I was talking about passed the blow test. But I will check with Joanns if I can find something adequate. I honestly don't want to spend more than $6 -$7 per yard unless I have to.

It seems like fire-treated fabric are expensive.

I will keep them in mind though.Thanks for the advice.


----------



## localhost127

have fun


----------



## seigneur_rayden




> Quote:
> Originally Posted by *localhost127* /forum/post/21017579
> 
> 
> have fun



Will do sir.


----------



## Davecraze

Room is 13 wide and x 17 long x 9 high and I will be using all in walls (AT screen) and approximately 128 square feet of 2 inch panels and 4 inch panels, in locations suggested by Bryan at GIK. One row is seating. I see that many folks are treating their whole front wall and I am thinking about covering the whole front wall in 1" or 2" acoustic panels. I am a little concerned about the room becoming too dead.


My question is: Is treating the whole front wall as important when one is using inwalls?


Thanks.


----------



## FOH




> Quote:
> Originally Posted by *Davecraze* /forum/post/21018646
> 
> 
> Room is 13 wide and x 17 long x 9 high and I will be using all in walls (AT screen) and approximately 128 square feet of 2 inch panels and 4 inch panels, in locations suggested by Bryan at GIK. One row is seating. I see that many folks are treating their whole front wall and I am thinking about covering the whole front wall in 1" or 2" acoustic panels. I am a little concerned about the room becoming too dead.
> 
> 
> My question is: Is treating the whole front wall as important when one is using inwalls?
> 
> 
> Thanks.



First, I'd contact Bryan, and unify the front wall treatment, with the remainder of what he's suggesting elsewhere. Typically, SBIR dictates front wall attention, however inwalls do mitigate that issue. However, as Toole and others have illustrated, typically the front wall benefits from some measure of absorption. As with any absorption, if you're going to do it, do it well. I'm not sure it's be a good idea to cover any surface with a thin layer of absorption, as that merely selectively attenuates wrt frequency. Thus not lowering much of the lower octave energy in the same manner as the upper ranges,..resulting in an imbalance.


IMO, if the situation warrants it, and you're going to absorb...do it well. Pay attention to incidence angles (side walls, ceilings), utilize spacing w/an air gap, and of course use adequate thickness.


Good luck


Toole's book is superb,... Sound Reproduction


----------



## FOH

Davecraze,


Very good question regarding in-walls, and treatment. Very few examples to draw from. However, Toole states in this paper;


"_Reflections from central portions of the front and back walls have the least positive contributions to what we hear. Attenuating them may be advantageous._"


Good luck


----------



## Al Sherwood

Like Davecraze, my room will have an AT screen up front and the speakers all mounted so that they are essentially in wall mounts. After reading some material on commercial installations they usually treat the entire front wall as FOH mentions. BTW thanks for the book suggestion FOH.


----------



## Ernstmach

Was wondering if anyone here has used this http://cmsgreen.com/product.html Product.

Found this at my local lumber yard. Bought a 4'X8'X1.5 inch piece to experiment with. Price $23.


----------



## myfipie




> Quote:
> Originally Posted by *FOH* /forum/post/21021173
> 
> 
> First, I'd contact Bryan, and unify the front wall treatment, with the remainder of what he's suggesting elsewhere. Typically, SBIR dictates front wall attention, however inwalls do mitigate that issue. However, as Toole and others have illustrated, typically the front wall benefits from some measure of absorption. As with any absorption, if you're going to do it, do it well. I'm not sure it's be a good idea to cover any surface with a thin layer of absorption, as that merely selectively attenuates wrt frequency. Thus not lowering much of the lower octave energy in the same manner as the upper ranges,..resulting in an imbalance.
> 
> 
> IMO, if the situation warrants it, and you're going to absorb...do it well. Pay attention to incidence angles (side walls, ceilings), utilize spacing w/an air gap, and of course use adequate thickness.
> 
> 
> Good luck
> 
> 
> Toole's book is superb,... Sound Reproduction



Good to see Bryan is helping you. As the others have said I would contact Bryan to get his thoughts on the matter.


----------



## Brucemck2

If there's an 18" square soffit around the entire ceiling perimeter of a 18'wx24'lx10'h room, is there much of any chance of "over treatment" or "overly deadening" the room if that's filled with pink fluffy?


I would assume "No" given that most of the wall and ceiling surfaces would remain reflective; I would assume the "over treatment" and "deadening" would apply to covering too much wall surface killing off the majority of reflections in the room?


----------



## pauleyc




> Quote:
> Originally Posted by *Brucemck2* /forum/post/21046247
> 
> 
> If there's an 18" square soffit around the entire ceiling perimeter of a 18'wx24'lx10'h room, is there much of any chance of "over treatment" or "overly deadening" the room if that's filled with pink fluffy?
> 
> 
> I would assume "No" given that most of the wall and ceiling surfaces would remain reflective; I would assume the "over treatment" and "deadening" would apply to covering too much wall surface killing off the majority of reflections in the room?



How do you plan on covering the soffit? I'm asking b/c if the majority of the room is 'reflective' then I'm guessing you are not using fabric on the soffit???


----------



## Brucemck2




> Quote:
> Originally Posted by *pauleyc* /forum/post/21047194
> 
> 
> How do you plan on covering the soffit? I'm asking b/c if the majority of the room is 'reflective' then I'm guessing you are not using fabric on the soffit???



Soffit would be covered with GOM or similar acoustically transparent fabric.


Core idea I'm asking is whether using a soffit around the ceiling perimeter of the room "deadens" the room beyond being a good (upper) bass trap.


I understand it's a great broad band down through upper bass absorber (a-la superchunks). I'm wondering how doing an entire soffit would compare -- in an adverse way with "deadening the sonics" -- to covering a good fraction of wall area with fiberglass absorbers.


----------



## Dennis Erskine




> Quote:
> I understand it's a great broad band down through upper bass absorber (a-la superchunks). I'm wondering how doing an entire soffit would compare -- in an adverse way with "deadening the sonics" -- to covering a good fraction of wall area with fiberglass absorbers.



Wouldn't be nice if it were that simple. If you had a stick built soffit filled with fluffy stuff and covered with fabric, you could easily over absorb high frequencies. If you covered the fluffy stuff with a membrane, you could increase lower frequency absorption (more mid-range) whilst reflecting higher frequency content. In the end, exposed soffits don't make good broadband absorbers (unless you do the math and determine if their contribution is worthwhile). To make a soffit helpful at the lower end of the spectra, you'd want fluffy stuff in the soffit but have the soffit open only in the corners of the room.


While the total amount of absorption by frequency is important, what is equally important is where that stuff is placed! That is further complicated when hybrid products are used ... like absorber/diffusors, and products designed to reflect higher frequencies and absorb lower. The whole strategy is also affected by seating location with respect to the room ... for example, if your seating is way off center, the strategy needs to address the fact that the left wall is considerbly further from the listener than the right wall. And, again, if your room has windows, those windows are low pass filters with an unknown (until measured) crossover frequency.


Simply putting fabric covered fiberglass panels in interesting places on walls and ceilings is not an option for a high performance room. That's where extensive modelling is helpful.


----------



## pepar

Not everyone ... in fact most people .. can't afford the "high performance" room that you provide.


However, there are a number of options out there that involve commercial products and recommendations from the companies that sell them (included in customer service they provide at no additional cost) that will achieve a really good performing room if it isn't horribly handicapped ((by dimensions) going in.


And then there are professionals that will, for a fixed fee, make recommendations on what to use where. Among others, AV Science (the people that operate this forum) offers such a service. As I understand it, it involves the customer providing information on the room including basic acoustical measurements and submitting the data for analysis.


And then there is always visiting a number of different forums with questions, and sorting through the whole thing as a DIY project.


The trick is to achieve the balance between performance and cost that works best for the theater owner.


Jeff


----------



## nickbuol

How bad is it to put soffits up before DD+GG?


I am hitting a snag in our local building inspection. They won't sign off on the rough in unless all finished areas are completely framed up. That would normally be fine, just would have to pay for a second rough in and second drywall inspection, however I have one area in the home theater that contains some plumbing pipes that were going to be hidden into the soffits AFTER I DD+GG then main walls. Well, that doesn't pass rough in inspection. Like I said, I need to either frame around the plumbing, or build the soffits and then DD+GG around them (with the appropriate boxes around the light fixtures, etc.


I know that it is not as good as doing the soffits after the room is "sealed up", but how bad would it be?


I've searched for about 2 hours now through this and other threads, and I am sure that this information is out there, but I am too tired to look any more (it is 1:40 am here). I told my wife that I was coming to bed at midnight... Oops...


----------



## fotto




> Quote:
> Originally Posted by *nickbuol* /forum/post/21056604
> 
> 
> How bad is it to put soffits up before DD+GG?
> 
> 
> I am hitting a snag in our local building inspection. They won't sign off on the rough in unless all finished areas are completely framed up. That would normally be fine, just would have to pay for a second rough in and second drywall inspection, however I have one area in the home theater that contains some plumbing pipes that were going to be hidden into the soffits AFTER I DD+GG then main walls. Well, that doesn't pass rough in inspection. Like I said, I need to either frame around the plumbing, or build the soffits and then DD+GG around them (with the appropriate boxes around the light fixtures, etc.
> 
> 
> I know that it is not as good as doing the soffits after the room is "sealed up", but how bad would it be?
> 
> 
> I've searched for about 2 hours now through this and other threads, and I am sure that this information is out there, but I am too tired to look any more (it is 1:40 am here). I told my wife that I was coming to bed at midnight... Oops...



AS long as you build it right (backer boxes for lights, etc) I don't believe you'll have any appreciable degradation in your sound proofing. Ted White has a nice install manual on various approaches you might email him for. People regularly enclose HVAC trunk lines etc here (including myself) where you can't get the whole room envelop done first.


----------



## nickbuol

Sounds good. I planned on some backer boxes, so maybe it will be OK. I will email the master himself (Ted) and see what he can share. Thanks again.


----------



## longshorejl

I have a couple questions concerning my theater. My space is 15 x 21 x 8. I have a fake front wall with 2" acoustic insulation covering it entirely. The rest of the room is drywall except the ceiling. Ceiling is gg dd plus a wood laminate finish. The basement is 4 poured cement walls with a cement slab floor. So i basically have a cement box with a sound tight lid. The floor will be dri-core plus carpet. I have one corner bass trap in the back of the room.


First, I plan to get a powerful sub like the DST-10. Is there anyway for me to get clean low frequencies? How would I trap for that?

Second, I see most people doing corner traps floor to ceiling in the front. Shouldn't these be covered with kraft paper to prevent absorbing mids and highs?


thanks,

Jim


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *longshorejl* /forum/post/21058847
> 
> 
> First, I plan to get a powerful sub like the DST-10. Is there anyway for me to get clean low frequencies? How would I trap for that?



1. Find the best location for the sub (fewest difficult nulls / peaks) - measure the room response to determine

2. EQ the sub - again, based on measurements

3. Bass traps can help some



> Quote:
> Originally Posted by *longshorejl* /forum/post/21058847
> 
> 
> Second, I see most people doing corner traps floor to ceiling in the front. Shouldn't these be covered with kraft paper to prevent absorbing mids and highs?
> 
> 
> thanks,
> 
> Jim



That would depend on what else is in the room


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *pepar* /forum/post/21050861
> 
> 
> Not everyone ... in fact most people .. can't afford the "high performance" room that you provide.
> 
> 
> And then there are professionals that will, for a fixed fee, make recommendations on what to use where. Among others, AV Science (the people that operate this forum) offers such a service. As I understand it, it involves the customer providing information on the room including basic acoustical measurements and submitting the data for analysis.
> 
> Jeff



So what is the dollar amount that defines "high performance"? High performance is not defined by a dollar figure, but by adherence to set of reference standards and the application and integration of those standards. Ornate is defined by a dollar figure (which is completely client driven)!







You can have a fairly unremarkable room aesthetically, but still sound and look incredible!










The room layout service provided by AVS does not require acoustical measurements of your room for submission. In fact, that would be quite difficult since we don't know where the listening position is, which means the best seating position, best sub placement, and speaker placement, etc. needs to be determined first; the point of the layout. Once the layout has been implemented, then you can take readings to your hearts content.


----------



## pepar

The kind Dennis was describing ... with extensive modeling ... is my context in this case for "high performance."










Thanks for the correction/expansion on AVS' room layout service. If I hadn't gone so far down the DIY road .. and not be so stubborn ... I would have utilized something like that.


Jeff


----------



## robc1976

Wanted your guys opinion on this because it is obvious there are a lot of knwoledgable people here, I recently treated my room (Nothing high grade, but it sounds great). I have seen posts of people putting diffusors behind there mains, and some do not suggest it...below are pics of my room and my proposed locations for the diffusors...any suggestions? I have 9.1 A-DSX if that helps. My new house is being bulit and should be finished in a year maybe a bit more and will upgrade when it is...but for now this will do.

*Front soundstage:*











*Right side of MLP:*











*Left side of MLP:*











*Above MLP:* (Need to rotae the 2 panels but this pic is just what I already have.










*Back-wall:*










By robc1976 at 2011-10-13


----------



## pepar

robc1976 - what changes did you notice when you added the diffusors over the listening area.


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21079419
> 
> 
> robc1976 - what changes did you notice when you added the diffusors over the listening area.
> 
> 
> Jeff



That was by far the biggest impact, the detail was much better and the sound was a lot fuller. The back wall really brought the surrounds in. But the detail is just amazing. The sound from the treatments is basically like the sound is "just there" no localization. I am planning on maybe adding 4 panels directly behind the listening area also.


----------



## nickbuol

Yeah, the problem with things for most is the good ol WAF factor. I would never be allowed to have so many panels in my theater, but I am sure that it makes an improvement.


----------



## robc1976




> Quote:
> Originally Posted by *nickbuol* /forum/post/21079960
> 
> 
> Yeah, the problem with things for most is the good ol WAF factor. I would never be allowed to have so many panels in my theater, but I am sure that it makes an improvement.



My wife actually is into it to, I guess I am lucky LOL!! She is thinking og putting some on the upstairs system.


----------



## nickbuol




> Quote:
> Originally Posted by *robc1976* /forum/post/21079971
> 
> 
> My wife actually is into it to, I guess I am lucky LOL!! She is thinking og putting some on the upstairs system.



You are a lucky man. My wife likes the theater, but she wants it to look "clean"... Well, that isn't going to happen since I will have wall treatments up when it is done and I am not going the path of having the entire walls covered with fabric covered panels like some (also lucky) people do.


----------



## robc1976




> Quote:
> Originally Posted by *nickbuol* /forum/post/21079997
> 
> 
> You are a lucky man. My wife likes the theater, but she wants it to look "clean"... Well, that isn't going to happen since I will have wall treatments up when it is done and I am not going the path of having the entire walls covered with fabric covered panels like some (also lucky) people do.



I agree....to be honest I like the look of the foam, really like some of the designs you can make. It does a good job INMHO.


----------



## mtbdudex




> Quote:
> Originally Posted by *robc1976* /forum/post/0
> 
> 
> I agree....to be honest I like the look of the foam, really like some of the designs you can make. It does a good job INMHO.



Have you taken objective measurements to grasp the changes you ears hear with data/charts? I'm using REW and ETC charts for the listening space as fine tuning tool to dial in the seating positions treatments for each speaker.


----------



## robc1976




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21080289
> 
> 
> Have you taken objective measurements to grasp the changes you ears hear with data/charts? I'm using REW and ETC charts for the listening space as fine tuning tool to dial in the seating positions treatments for each speaker.



Thats my next step, I basically had auralex recommend "general placement", then added the diffusors with info here. Anyone have any opinions on placement of the diffusors in the pics I posted above? also I was strongly thinking of adding another absorbion panel on the door also because it seems it is in a reflection point, I just dont want to over do it with absorbtion.


----------



## robc1976

I have heard that say no treatments should be around the surroounds...is this true??

*here is mine:*


----------



## FOH




> Quote:
> Originally Posted by *robc1976* /forum/post/21107310
> 
> 
> I have heard that say no treatments should be around the surroounds...is this true??



I believe what you'll find wrt acoustics for small rooms, is that there are few hard a fast rules. So, to say treatments are either needed, or un-necessary around surrounds can't be determined to be one thing for all situations. Each situation is different, due to proximity of all adjacent boundaries, distance to listening position, speaker type, boundary construction, surface treatments, floor coverings etc. Anyway, the point being is everything is inter-dependent.


What you will find however is relatively thin foam products, such as shown in your pic, are typically poor performers wrt broadband absorption. They simply can't attenuate effectively down into the frequency range necessary. Generally, materials such as Owens Corning 703(3lbs density), covered in acoustically transparent fabric, and a thickness of 4"-6", and spaced off the wall or surface is extremely effective for the intended purpose. The problem with thinner foams, or other similar materials, is they absorb merely the higher frequencies, leaving a duller sounding result. Oftentimes doing more harm than good.

Here is an outstanding guide on room acoustics by Ethan Winer, a frequent AVS contributor. It is truly a wealth of great information.


Also, if you're not familiar with SBIR , and it's effects, you may want to read here .


Good luck


----------



## robc1976




> Quote:
> Originally Posted by *FOH* /forum/post/21108326
> 
> 
> I believe what you'll find wrt acoustics for small rooms, is that there are few hard a fast rules. So, to say treatments are either needed, or un-necessary around surrounds can't be determined to be one thing for all situations. Each situation is different, due to proximity of all adjacent boundaries, distance to listening position, speaker type, boundary construction, surface treatments, floor coverings etc. Anyway, the point being is everything is inter-dependent.
> 
> 
> What you will find however is relatively thin foam products, such as shown in your pic, are typically poor performers wrt broadband absorption. They simply can't attenuate effectively down into the frequency range necessary. Generally, materials such as Owens Corning 703(3lbs density), covered in acoustically transparent fabric, and a thickness of 4"-6", and spaced off the wall or surface is extremely effective for the intended purpose. The problem with thinner foams, or other similar materials, is they absorb merely the higher frequencies, leaving a duller sounding result. Oftentimes doing more harm than good.
> 
> Here is an outstanding guide on room acoustics by Ethan Winer, a frequent AVS contributor. It is truly a wealth of great information.
> 
> 
> Also, if you're not familiar with SBIR , and it's effects, you may want to read here .
> 
> 
> Good luck



Thatnis great info, yeah I am planning on geeting a products fron "RealTraps" I believe I have seen Ethan there many times and he is a expert for sure. Once my house is built I will do this but for now I must admit the 2" foam did make the sound better...well the bass traps to. I have 9 horned tweeters so I am bettinf thyey throw some high notes out LOL! My original post was not written right I meant to say "Shouldn't be used" LOL!!


----------



## robc1976




> Quote:
> Originally Posted by *FOH* /forum/post/21108326
> 
> 
> I believe what you'll find wrt acoustics for small rooms, is that there are few hard a fast rules. So, to say treatments are either needed, or un-necessary around surrounds can't be determined to be one thing for all situations. Each situation is different, due to proximity of all adjacent boundaries, distance to listening position, speaker type, boundary construction, surface treatments, floor coverings etc. Anyway, the point being is everything is inter-dependent.
> 
> 
> What you will find however is relatively thin foam products, such as shown in your pic, are typically poor performers wrt broadband absorption. They simply can't attenuate effectively down into the frequency range necessary. Generally, materials such as Owens Corning 703(3lbs density), covered in acoustically transparent fabric, and a thickness of 4"-6", and spaced off the wall or surface is extremely effective for the intended purpose. The problem with thinner foams, or other similar materials, is they absorb merely the higher frequencies, leaving a duller sounding result. Oftentimes doing more harm than good.
> 
> Here is an outstanding guide on room acoustics by Ethan Winer, a frequent AVS contributor. It is truly a wealth of great information.
> 
> 
> Also, if you're not familiar with SBIR , and it's effects, you may want to read here .
> 
> 
> Good luck



Really good reading here, just answered my next question I believe, I was wondering how much spce ypu cover for the reflection point of the ceiling...well I have Audyssey DSX and my refection points are pretty close together so I jusyt covered a large are with mainly the 2" foam and some diffusiion near it and over MLP and wondered if I should space out the panels but Ethan says not to.


----------



## nickbuol

I found some mineral wool today while out and about over lunch, but I couldn't find out if it would work for super chunk bass traps or for first point reflection panels.


The specs are:

Thermafiber brand mineral wool "safing insulation".


4 inch thick, 2 foot x 4 foot panels
Thermafiber R-16.8 Mineral Wool 


I can't find a pcf rating anywhere... Not on the packaging, not at Menards.com, not at Thermafiber's web site.


Maybe it is completely wrong. I just noticed that the in-store price was on sale for about $10 cheaper for a 5 sheet bundle the online price is normally less than in-store, but then you have to get it shipped.


Any thoughts? Sale price is good for 2 more days, so if this will work OK, I might stock up on it now.


----------



## Brad Horstkotte

 http://www.thermafiber.com/images/up...ta%20sheet.pdf 


available as 4 pcf and 6 pcf, which is a little higher than is usually used for super chunks - not saying it won't work, but not a dead ringer substitute for the "usual suspects".


----------



## nickbuol

OK. Thanks. It was worth checking, and I appreciate the response. I am probably a month out yet from having my theater room drywalled, and the flooring started, so I have time. I just saw these today and thought I would inquire.


----------



## robc1976

Is it sugggested to treat behind the screen, maybe at the height of the center channel so there is absorbtion behind the center?


Here is my TV:


----------



## pepar

I would treat behind the _center channel speaker_ with something similar to L&R, though the same height mounting may not be necessary. So, yes.










Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21118761
> 
> 
> I would treat behind the _center channel speaker_ with something similar to L&R, though the same height mounting may not be necessary. So, yes.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



I was thinking may a 3 piece triangle but lower......Thanks man!!


----------



## robc1976




> Quote:
> Originally Posted by *FOH* /forum/post/21108326
> 
> 
> I believe what you'll find wrt acoustics for small rooms, is that there are few hard a fast rules. So, to say treatments are either needed, or un-necessary around surrounds can't be determined to be one thing for all situations. Each situation is different, due to proximity of all adjacent boundaries, distance to listening position, speaker type, boundary construction, surface treatments, floor coverings etc. Anyway, the point being is everything is inter-dependent.
> 
> 
> What you will find however is relatively thin foam products, such as shown in your pic, are typically poor performers wrt broadband absorption. They simply can't attenuate effectively down into the frequency range necessary. Generally, materials such as Owens Corning 703(3lbs density), covered in acoustically transparent fabric, and a thickness of 4"-6", and spaced off the wall or surface is extremely effective for the intended purpose. The problem with thinner foams, or other similar materials, is they absorb merely the higher frequencies, leaving a duller sounding result. Oftentimes doing more harm than good.
> 
> Here is an outstanding guide on room acoustics by Ethan Winer, a frequent AVS contributor. It is truly a wealth of great information.
> 
> 
> Also, if you're not familiar with SBIR , and it's effects, you may want to read here .
> 
> 
> Good luck



Once I my nhouse built and i am out of this one I was going to have "RealTraps" tretments everywhere or maybe "Auralex Elite series".


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21118761
> 
> 
> I would treat behind the _center channel speaker_ with something similar to L&R, though the same height mounting may not be necessary. So, yes.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



How about a bass trap above the Tv on the ceiling vertical where the wall meets the ceiling?


----------



## pepar




> Quote:
> Originally Posted by *robc1976* /forum/post/21120880
> 
> 
> How about a bass trap above the Tv on the ceiling vertical where the wall meets the ceiling?



Sure, corners are the best place for those.


If you're not already, it's probably a good idea for you to pick up some measuring software and a calibrated mic. That way you can identify problems before you solve them.










Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21121147
> 
> 
> Sure, corners are the best place for those.
> 
> 
> If you're not already, it's probably a good idea for you to pick up some measuring software and a calibrated mic. That way you can identify problems before you solve them.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



I have all coners trapped, even where the Hvac duct meets the wall...I agree...time for measuring software.....any you suggest?


I appreciate the help!


----------



## pepar




> Quote:
> Originally Posted by *robc1976* /forum/post/21121384
> 
> 
> I have all coners trapped, even where the Hvac duct meets the wall...I agree...time for measuring software.....any you suggest?
> 
> 
> I appreciate the help!



Running on Windows laptops, the lot of them ...


There is the venerable Room EQ Wizard. It's free, but needs a calibrated and probably a USB preamp. Probable $200-ish.


There is XTZ, a self-contained solution for around $300. And there is Dayton Omnimic, another all-in-one product also for around $350.


REW is a lot more capable, but there is a learning curve - with a very helpful forum dedicated to it. The other two are more than adequate for many things you'll want to do, with very little learning curve, but more expensive.


----------



## riverwolf




> Quote:
> Originally Posted by *pepar* /forum/post/21121545
> 
> 
> Running on Windows laptops, the lot of them ...
> 
> 
> There is the venerable Room EQ Wizard. It's free, but needs a calibrated and probably a USB preamp. Probable $200-ish.
> 
> 
> There is XTZ, a self-contained solution for around $300. And there is Dayton Omnimic, another all-in-one product also for around $350.
> 
> 
> REW is a lot more capable, but there is a learning curve - with a very helpful forum dedicated to it. The other two are more than adequate for many things you'll want to do, with very little learning curve, but more expensive.



A REW setup is easily doable for $100, maybe less with patience and sales. Each EMM-6 includes a mic specific 20-20k calibration file. Looks like regular price has bumped up a bit to $48, but seems to routinely go on sale for upper $30s. For a preamp, I'd probably go with the 302USB for $50 although the Blue Icicle USB pre would probably get the job done. Wish that 302 had been around last year when I bought my Xenyx 802, which doesn't have a USB interface


-Brent


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21121545
> 
> 
> Running on Windows laptops, the lot of them ...
> 
> 
> There is the venerable Room EQ Wizard. It's free, but needs a calibrated and probably a USB preamp. Probable $200-ish.
> 
> 
> There is XTZ, a self-contained solution for around $300. And there is Dayton Omnimic, another all-in-one product also for around $350.
> 
> 
> REW is a lot more capable, but there is a learning curve - with a very helpful forum dedicated to it. The other two are more than adequate for many things you'll want to do, with very little learning curve, but more expensive.



I was thinking about getting the Audyssey pro also so will these be compatible?


----------



## robc1976

Pepar,


Your advice was right again, Finally the audyssey curve has detail that I want....the tretments behind the center really brought out the detail! I may actually remove some absorbtion from my surrounds though.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21121384
> 
> 
> I have all coners trapped, even where the Hvac duct meets the wall...I agree...time for measuring software.....any you suggest?
> 
> 
> I appreciate the help!



i would caution the effectiveness of the foam products that are visible in the corners of your room (in your posted photos) - if that is what you are referring to as 'bass traps'.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21121667
> 
> 
> Pepar,
> 
> 
> Your advice was right again, Finally the audyssey curve has detail that I want....the tretments behind the center really brought out the detail! I may actually remove some absorbtion from my surrounds though.













what specular energy is being radiated directly behind your center/surround speakers that supports the need for absorption? and be careful when applying thin absorption as you have, as it will merely soak up the HF content which has the least amount of energy content as it is ... allowing mid-lower specular energy to persist in the room.


it is all too easy to over-damp the HF


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21121732
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> what specular energy is being radiated directly behind your center/surround speakers that supports the need for absorption? and be careful when applying thin absorption as you have, as it will merely soak up the HF content which has the least amount of energy content as it is ... allowing mid-lower specular energy to persist in the room.
> 
> 
> it is all too easy to over-damp the HF



From one of his earlier posts ...











I suggested he move the absorption above the listening area (leaving the diffusion) to the first reflection point on the front ceiling. All in all, it doesn't "look" like he's close to over-anything-ing yet.


robc1976, localhost127 is right about bass traps. Here is the kind you should look into.


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *Terry Montlick* /forum/post/6549378
> 
> 
> I'm with Brian. I only deal with LCR early reflections. Surround sound reflections are not an issue for home theaters, as they do not affect the front sound stage.
> 
> 
> - Terry



So no absorbtion behind the surround speaker or early/2nd reflection points on surrounds? My pic of my surround speaker is below.


----------



## robc1976

Was reading a lot of this thread and someone stated you can have to many traps, I basically have 3 in each corner with a 3" gap in between and 2 where the air duct meats the wall so a total of 12 traps.


I am using these:

http://www.auralex.com/bass_traps_le...raps_lenrd.asp 



Thanks guys.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21123132
> 
> 
> Was reading a lot of this thread and someone stated you can have to many traps, I basically have 3 in each corner with a 3" gap in between and 2 where the air duct meats the wall so a total of 12 traps.
> 
> 
> I am using these:
> 
> http://www.auralex.com/bass_traps_le...raps_lenrd.asp
> 
> 
> 
> Thanks guys.



you cannot have too much LF absorption within small acoustical spaces - the problem becomes when people use porous, broadband bass traps that inadvertently absorb the specular region too - quickly creating a dead space. this is generally why it is advised to place a reflective covering over the bass trap to reflect some mid-high specular content back into the room (eg, 6mil plastic).


regarding your link,

no, those are not bass traps no matter what the description says.



> Quote:
> Originally Posted by *robc1976* /forum/post/21123118
> 
> 
> So no absorbtion behind the surround speaker or early/2nd reflection points on surrounds? My pic of my surround speaker is below.



im just questioning why you need absorption directly behind the speaker when there is little specular content being radiated behind the cabinet? not to mention, you are applying thin absorption which will soak the HF content out of the room, allowing the mid-lower specular content to persist (which has the most amount of energy content and as such, requires the most attention).


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21122549
> 
> 
> From one of his earlier posts ...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I suggested he move the absorption above the listening area (leaving the diffusion) to the first reflection point on the front ceiling. *All in all, it doesn't "look" like he's close to over-anything-ing yet.*



it looks like over-applying treatments (absorption + diffusion) that addresses HF content only ....



> Quote:
> Originally Posted by *pepar* /forum/post/21122549
> 
> 
> robc1976, localhost127 is right about bass traps. Here is the kind you should look into.
> 
> 
> Jeff



yes, but making them out of oc703 is expensive and not as effective as they could be. cheaper and more effective options exist.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21123427
> 
> 
> it looks like over-applying treatments (absorption + diffusion) that addresses HF content only ....



I think he thought he *was* addressing LF with his Auralex LENRDs. The Mega LENRD s test better , so maybe go that route.


Or a DIY solution.


Parting comment .. he had a tall bar a few inches behind the heads of the listeners. He removed that and said the sound improved dramatically. I think he had some problems so big that removing them was the first task. Now he can focus on what you cite. He's looking into measuring software, too.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21123885
> 
> 
> I think he thought he *was* addressing LF with his Auralex LENRDs. The Mega LENRD s test better , so maybe go that route.



i dont consider those foam corner wedges to be "addressing" LF issues at all..


he could likely make big, deep corner porous traps made from pink fluffy insulation that will be more effective than the foam traps, and likely to cost considerably less - if he is willing to go the DIY route.


when i said his existing treatments are over-treating HF content only, i didnt meant HF vs LF (bass) ... i meant the High Freq content of the specular region.


the thin absorption and shallow diffusers are effective for HF content only, not the mid to lower specular range (this area has nothing to do with LF/bass). all of that thin treatment is essentially EQ'ing the room by removing the HF specular energy and allowing the mid-lower specular energy (down to ~300hz) to persist. the lowest range of the specular region is where the bulk of the energy is to begin with - so that's why it is important to address.


it's all too easy to absorb HF specular content (thin foam) - but does his foam attenuate the entire specular reflection? unlikely... but easily measured via the ETC.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21123935
> 
> 
> i dont consider those foam corner wedges to be "addressing" LF issues at all..



So when the StudioTips corner absorber test says ..
*

1) All 3 absorbers have considerable low frequency absorption.* (MegaLENRD, StudioTips SuperChunk and StudioTips Corner Absorbers)*


2) Acoustic Foam has low frequency absorption performance comparable to mineral wools.*


.. they are mistaken?


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21123978
> 
> 
> So when the StudioTips corner absorber test says ..
> *
> 
> 1) All 3 absorbers have considerable low frequency absorption.* (MegaLENRD, StudioTips SuperChunk and StudioTips Corner Absorbers)*
> 
> 
> 2) Acoustic Foam has low frequency absorption performance comparable to mineral wools.*
> 
> 
> .. they are mistaken?
> 
> 
> Jeff



1 - my comment was with regards to the foam wedges in his photos. understand the context of my comment before attempting to change the entire scope of the statement and flagrantly attempt to add in other random products as you did above...











do you think those relatively shallow foam corner wedges (with unknown flow-resistivity values!) of which are sparsely deployed are going to have a great effect on LF?


2 - im afraid the commentary there has little understanding on the importance of flow-resistivity with regards to materials selection. look how many are still dead-set on using OC703 or equivalent mineral wool for their corner traps...

*do you understand the specific criteria to build an effective porous LF absorber?*


and what does my original comment have anything to do with the performance of superchunks? didn't i just recommend him to build superchunks in my previous post?


and you may with to read this document to learn a bit more of the difficulties of such measurements regarding LF absorption:
http://downloads.bbc.co.uk/rd/pubs/reports/1982-04.pdf 


the fact remains that i offered a cheaper and more effective LF porous bass trap solution than the expensive foam products others are pushing.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21123415
> 
> 
> you cannot have too much LF absorption within small acoustical spaces - the problem becomes when people use porous, broadband bass traps that inadvertently absorb the specular region too - quickly creating a dead space. this is generally why it is advised to place a reflective covering over the bass trap to reflect some mid-high specular content back into the room (eg, 6mil plastic).
> 
> 
> regarding your link,
> 
> no, those are not bass traps no matter what the description says.
> 
> 
> 
> 
> im just questioning why you need absorption directly behind the speaker when there is little specular content being radiated behind the cabinet? not to mention, you are applying thin absorption which will soak the HF content out of the room, allowing the mid-lower specular content to persist (which has the most amount of energy content and as such, requires the most attention).



I agree with the surrounds, I would think no absorbtion would be needed here, I can see haveing it in my font soundstage though...so should I remove it from the surrounds? I am sure you are right about the traps, but they made a HUGE improvement. My new house is being built and will be completed in about 2 years or so and I am going with "Realltraps" or "auralex elite" or another company somone suggests. I have the foam (I know oit is not the best) but it has amd a great improvement. My new room will be 44' deep X 30' wide with 11' vaulted celing. when they get to that area I am really going to have some decisions to make (walll construction,fllor construction ect!) Everyones help is VERY much appreciated!


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21124162
> 
> 
> 1 - my comment was with regards to the foam wedges in his photos. understand the context of my comment before attempting to change the entire scope of the statement and flagrantly attempt to add in other random products as you did above...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> do you think those relatively shallow foam corner wedges (with unknown flow-resistivity values!) of which are sparsely deployed are going to have a great effect on LF?
> 
> 
> 2 - im afraid the commentary there has little understanding on the importance of flow-resistivity with regards to materials selection. look how many are still dead-set on using OC703 or equivalent mineral wool for their corner traps...
> 
> *do you understand the specific criteria to build an effective porous LF absorber?*
> 
> 
> and what does my original comment have anything to do with the performance of superchunks? didn't i just recommend him to build superchunks in my previous post?
> 
> 
> and you may with to read this document to learn a bit more of the difficulties of such measurements regarding LF absorption:
> http://downloads.bbc.co.uk/rd/pubs/reports/1982-04.pdf
> 
> 
> the fact remains that i offered a cheaper and more effective LF porous bass trap solution than the expensive foam products others are pushing.



I am not queationing you at all...it is very clear you know WAY more than I do and I totally respect that...heck you have probally forgotten more than I know LOL!!


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21123885
> 
> 
> I think he thought he *was* addressing LF with his Auralex LENRDs. The Mega LENRD s test better , so maybe go that route.
> 
> 
> Or a DIY solution.
> 
> 
> Parting comment .. he had a tall bar a few inches behind the heads of the listeners. He removed that and said the sound improved dramatically. I think he had some problems so big that removing them was the first task. Now he can focus on what you cite. He's looking into measuring software, too.
> 
> 
> Jeff



Thank you pepar for that reccomendation to...removing the bar made a HUGE difference, as welll as the absorbtion you sugggested on the ceiling for the center/fronts/wides celing reflection points.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21124162
> 
> 
> 1 - my comment was with regards to the foam wedges in his photos. understand the context of my comment before attempting to change the entire scope of the statement and flagrantly attempt to add in other random products as you did above...
> 
> 
> do you think those relatively shallow foam corner wedges (with unknown flow-resistivity values!) of which are sparsely deployed are going to have a great effect on LF?
> 
> 
> 2 - im afraid the commentary there has little understanding on the importance of flow-resistivity with regards to materials selection. look how many are still dead-set on using OC703 or equivalent mineral wool for their corner traps...
> 
> *do you understand the specific criteria to build an effective porous LF absorber?*
> 
> 
> and what does my original comment have anything to do with the performance of superchunks? didn't i just recommend him to build superchunks in my previous post?
> 
> 
> and you may with to read this document to learn a bit more of the difficulties of such measurements regarding LF absorption:
> http://downloads.bbc.co.uk/rd/pubs/reports/1982-04.pdf
> 
> 
> the fact remains that i offered a cheaper and more effective LF porous bass trap solution than the expensive foam products others are pushing.



I can't argue _their_ position/thinking on corner absorbers, but I will attempt to reduce my flagrancy.










It does appear, though, that the bigger foam tested similar to the chunks, and at least the test methodology was consistent making the comparison easy. Looking at one vendor's tests, and in some cases that's a charitable characterization, and comparing to another's is .. what, impossible?


Independent testing is rare, and that's why I keep referring to StudioTips.


Jeff


----------



## robc1976

I do have a question though...say for instance you find your refection point...how much treatment is needed in that area? Say the reflection point hits near the center og one og my 2' X 2' X 2" foam panels......is that enough treatment or should more be added? I would think more than one square would be needed so I am asking you guys.


----------



## robc1976

*Localhost127:*


You say some of my HF are being absorbed by the foam, would it them make sense to use the Audyssey flat curve since it has no frequency roll off?


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21124584
> 
> 
> 
> Independent testing is rare, and that's why I keep referring to StudioTips.
> 
> 
> Jeff



it's not independent testing that's the issue, it's the inherent nature of testing LF absorption to begin with.

http://downloads.bbc.co.uk/rd/pubs/reports/1982-04.pdf


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21125094
> 
> 
> I do have a question though...say for instance you find your refection point...how much treatment is needed in that area? Say the reflection point hits near the center og one og my 2' X 2' X 2" foam panels......is that enough treatment or should more be added? I would think more than one square would be needed so I am asking you guys.



a specular reflection is attenuated based on gain (-X dB) from the original signal. we do not break up individual specular reflections in terms of frequency.


eg, one usually attenuates the reflection such that it is below the human detection threshold (~-20dB, depending on arrival time) - such that the cues of the reflection are not processed by the brain (this does not mean the reflection isn't "heard" !)


therefore, the specular broadband absorber needs to be thick enough to be spaced away from the boundary such that it is placed in areas of high particle velocity to the lowest frequencies of the specular region.


typically, OC703 3pcf or 4pcf mineral wool, 4" thick with a 2-4" air-gap will achieve this, down to the lower specular region (~300hz).


bear in mind also, sound has size. so you need your broadband absorbers to be large with respect to the wavelength that they will be absorbing.


luckily, industrial batts of OC703/mineral wool come in 48" x 24" panels, and can be stacked to create appropriate thickness.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21125258
> 
> 
> it's not independent testing that's the issue, it's the inherent nature of testing LF absorption to begin with.
> 
> http://downloads.bbc.co.uk/rd/pubs/reports/1982-04.pdf



R-r-r-ight, I'm sure that any day now everybody will switch to using the statistical absorption coefficient in their specs.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21125356
> 
> 
> R-r-r-ight, I'm sure that any day now everybody will switch to using the statistical absorption coefficient in their specs.
> 
> 
> Jeff



you missed the point of my comment, then.


----------



## nickbuol

Oh boy. Not sure if I should jump in or not.


I know of nobody, minus the poster above, who is using foam panels in their home theater and expecting it to do low frequency trapping. Heck, I don't think that I recall seeing anyone using the foam products at all. Not saying that they might not tame some highs, but for lows, I can't imagine that their lacking density would stack up to denser products like the 703 or 705 type mineral wools or whatever you care to call them depending on who is making them.


One has to ask, why is that?


Now, I'm not going to say that the massive amount of colored foam panels above aren't doing *something*... I haven't been in that room, so I haven't heard, and thus I can't comment directly on it. I just think that it made some sort of improvement in what the user wanted and that is what counts. Best bang for the buck or even best sound control for a room, doubtful, but again, it isn't my room, and it isn't my buck.


Personally, I'm going with straight up, known to work, 703 panels and super chunk bass traps. They work for sure, and I've not afraid to build them.


Let's all just let it be. Some people just aren't willing to "see the light", regardless of which direction it is shining from.


----------



## robc1976




> Quote:
> Originally Posted by *nickbuol* /forum/post/21127619
> 
> 
> Oh boy. Not sure if I should jump in or not.
> 
> 
> I know of nobody, minus the poster above, who is using foam panels in their home theater and expecting it to do low frequency trapping. Heck, I don't think that I recall seeing anyone using the foam products at all. Not saying that they might not tame some highs, but for lows, I can't imagine that their lacking density would stack up to denser products like the 703 or 705 type mineral wools or whatever you care to call them depending on who is making them.
> 
> 
> One has to ask, why is that?
> 
> 
> Now, I'm not going to say that the massive amount of colored foam panels above aren't doing *something*... I haven't been in that room, so I haven't heard, and thus I can't comment directly on it. I just think that it made some sort of improvement in what the user wanted and that is what counts. Best bang for the buck or even best sound control for a room, doubtful, but again, it isn't my room, and it isn't my buck.
> 
> 
> Personally, I'm going with straight up, known to work, 703 panels and super chunk bass traps. They work for sure, and I've not afraid to build them.
> 
> 
> Let's all just let it be. Some people just aren't willing to "see the light", regardless of which direction it is shining from.



Keep in mind I will be using "realtraps" in my new house...couldn't see spending that kind of money on this when I am going to be upgrading to bigger better room LOL!! The foam did do something, will it compare to the products you guys are using...not hardly. I am new at this so I figured this would give me some on hands leaning on placement, what does what, what not to do and to tell ya the truth I diddn't know any better when I bought the foam. It was $20.00 for a 4' X 2' X 2" panel wich was half the price LOL!! I am learning a lot from a lot of you guiys and actually welcome the critisizm because that is how you learn......"I see the light, I just need to be directed"







I will listen to you guys, you know more than I and I appreciate you sharing your knowledge.


My 2 cents on the foam:


1. Better crisper sound

2. Made the bass tighter

3. less localization.


----------



## localhost127




> Quote:
> Originally Posted by *nickbuol* /forum/post/21127619
> 
> 
> Oh boy. Not sure if I should jump in or not.
> 
> 
> I know of nobody, minus the poster above, who is using foam panels in their home theater and expecting it to do low frequency trapping. Heck, I don't think that I recall seeing anyone using the foam products at all. Not saying that they might not tame some highs, but for lows, I can't imagine that their lacking density would stack up to denser products like the 703 or 705 type mineral wools or whatever you care to call them depending on who is making them.
> 
> 
> One has to ask, why is that?



there is open-cell foam out there that will perform - it's just a matter of cost.

as for the auralex foam...who knows? have they published specs of the material? GFR values? etc...


and flow-resistivity is the key value, not density...



> Quote:
> Originally Posted by *nickbuol* /forum/post/21127619
> 
> 
> Personally, I'm going with straight up, known to work, 703 panels and super chunk bass traps. They work for sure, and I've not afraid to build them.
> 
> 
> Let's all just let it be. Some people just aren't willing to "see the light", regardless of which direction it is shining from.



save the expensive OC703 for broadband absorbers for attenuate specular reflections. OC703 is not the most effective porous material for corner bass traps. you need thick traps to adequately absorb LF content, and as the traps are made deeper and deeper, you need to use material with lower GFR.


making superchunks out of OC703 is ridiculously expensive and cheaper alternatives exist of which will perform better.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21125706
> 
> 
> you missed the point of my comment, then.



it might be dawning on me slowly that you were questioning the measuring protocol that allowed the foam to "test" similar to the 'glass traps. if that wasn't your point, then i am too dense and it should probably be dropped.


jeff


----------



## NicksHitachi




> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> 
> there is open-cell foam out there that will perform - it's just a matter of cost.
> 
> as for the auralex foam...who knows? have they published specs of the material? GFR values? etc...
> 
> 
> and flow-resistivity is the key value, not density...
> 
> 
> save the expensive OC703 for broadband absorbers for attenuate specular reflections. OC703 is not the most effective porous material for corner bass traps. you need thick traps to adequately absorb LF content, and as the traps are made deeper and deeper, you need to use material with lower GFR.
> 
> 
> making superchunks out of OC703 is ridiculously expensive and cheaper alternatives exist of which will perform better.



What is more effective and cheaper for corner bass traps than OC703?


----------



## pepar




> Quote:
> Originally Posted by *nickbuol* /forum/post/21127619
> 
> 
> 
> Personally, I'm going with straight up, known to work, 703 panels and super chunk bass traps. They work for sure, and I've not afraid to build them.


 +1


----------



## pepar




> Quote:
> Originally Posted by *robc1976* /forum/post/21127703
> 
> 
> 
> My 2 cents on the foam:
> 
> 
> 1. Better crisper sound
> 
> 2. Made the bass tighter
> 
> 3. less localization.



Don't know about #3, but the other two are what you get whenever you reduce LF ringing which masks the entire frequency range.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21128320
> 
> 
> What is more effective and cheaper for corner bass traps than OC703?



cheap, pink fluffy attic insulation (uncompressed).


gas flow resistivity value of the porous material is what's important. 34" faced superchunks of pink fluffy (or larger, if you can do it). UNCOMPRESSED. you will need horizontal supports every few feet such that the layers at the top do not compress the layers at the bottom.


----------



## NicksHitachi




> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> 
> cheap, pink fluffy attic insulation (uncompressed).
> 
> 
> gas flow resistivity value of the porous material is what's important. 34" faced superchunks of pink fluffy (or larger, if you can do it). UNCOMPRESSED. you will need horizontal supports every few feet such that the layers at the top do not compress the layers at the bottom.



Is this opinion shared by most? What's the lower frequency limit of it's effectiveness?


Hmmm I was under the impression that 703 was the way to go...... Fluffy pink is Waaaay cheaper!


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21128400
> 
> 
> Is this opinion shared by most?



most certainly not. but what else do you expect from herd-mentality. why does opinion matter with regards to basic physics?



> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21128400
> 
> 
> What's the lower frequency limit of it's effectiveness?



depends on thickness of trap, and spacing of the insulation is areas of higher particle velocity.



OC703 (16,500 rayls/m)


http://imgur.com/u1QVB.png%5B/IMG%5D



pink fluffy (5000 rayls/m)


http://imgur.com/I5LcQ.png%5B/IMG%5D


----------



## robc1976

Can somone link me some good companies with good products, I like "realtraps" they make good products but I would like to see others to compare and figured you guys would know who to go to.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21129463
> 
> 
> Can somone link me some good companies with good products, I like "realtraps" they make good products but I would like to see others to compare and figured you guys would know who to go to.



is DIY out of the question?


it is also wise to have measurements of the room to understand the inherent issues that need to be addressed before selecting appropriate 'treatment' to address said issues.


----------



## pepar




> Quote:
> Originally Posted by *robc1976* /forum/post/21129463
> 
> 
> Can somone link me some good companies with good products, I like "realtraps" they make good products but I would like to see others to compare and figured you guys would know who to go to.



GIK Acoustics sells products about as reasonably as you will find.


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21128341
> 
> 
> Don't know about #3, but the other two are what you get whenever you reduce LF ringing which masks the entire frequency range.
> 
> 
> Jeff



That makes sense, Also the sound is better with the bar gone but I think the bass is a little less but I am getting another sub also...probally a null in that area.


----------



## NicksHitachi

What does the "rigid backed" in rigid backed porus absorber mean?


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21130126
> 
> 
> What does the "rigid backed" in rigid backed porus absorber mean?



the boundary is solid.


it does *not* mean that there is a rigid backing on the back of the trap.


if you are doing corner superchunks, then this is a null issue.


if you are building a panel and having it straddling the corner, then you want the rear of the absorber to be open (eg, no plywood/hard backing on the back side/face of the absorber).



http://imgur.com/buwNv.gif%5B/IMG%5D


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21129892
> 
> 
> GIK Acoustics sells products about as reasonably as you will find.
> 
> 
> Jeff



Thanks Pepar! I was thinking about thyese products, any opinions? How many panels for each reflection point? They are 2' X 4' and my speakers are pretty close to the walls since I have wide speakers. Behind the mains I was thinking 2 panels? I want to do this right this time and get some opinions from people who know and have experience, I will be purchasing this pretty soon.

*These for the first reflection points on the walls and behind the speakers as well as reflection points on the ceiling:*

http://www.gikacoustics.com/gik_242.html 

*These for bass traps, they are 4' tall and I need 7' though?? I was told to start at the top and work your way down...would a 4' trap be okay in all corners of the room? If not how do I add more when there is no more room?*

http://www.gikacoustics.com/gik_tri_trap.html 

*Diffusion over MLP and back wall: 9 (I have a air duct over MLP, don't mind putting screws thru it either.)*

http://www.gikacoustics.com/gik_tri_trap.html 

*Diffussion on 3 drop tiles in front of MLP:*

http://www.gikacoustics.com/gik_gridfusor.html


----------



## robc1976

Here is the performance data for the 2" studio foam and lenrds bass traps...can someone read this and tell us/me what alll this means...I will be honest and say I have no idea LOL!!









*2" studio-foam*

http://www.auralex.com/testdata/test/2wedge.pdf 

*Lenrds bass trap:*

http://www.auralex.com/testdata/test/lenrd.pdf 

*There other products:*

http://www.auralex.com/testdata/


----------



## pepar

GIK gives recommendations as as part of their customer service.


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21130228
> 
> 
> GIK gives recommendations as as part of their customer service.
> 
> 
> Jeff



Like a room anaylis?


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21129690
> 
> 
> is DIY out of the question?
> 
> 
> it is also wise to have measurements of the room to understand the inherent issues that need to be addressed before selecting appropriate 'treatment' to address said issues.



If it looks good sure, and I agree.


----------



## robc1976

Okay guys, I would like some advice if possible...I know I am using foam and it is not the best but I am getting much better in about 2-3 months and would just like to make the foam work the best it can for the time being. In the pics below I have a pic of panels numbered so it is easier to understand what you are taking about if you guys suggest I move a panel, remove ECT, below are the pics of the left side of MLP (one that needs help the most LOL!!) and Right side MLP and both 1st and 2nd reflections.....any suggestions are VERY much appreciated on placement, taking a panel down wich I am sure will be suggested. I noticed on the right side of MLP alll 1st and 2nd refections are on 2 panels.

*From what I see on left side:*


panel #1 (removed)

panel #2 (Moved up)

panel #3 (Moved down)

panel #4 (Removed)

panel #5 (Removed)

panel #6 (Moved down)

panel #7 (Removed)

panel #8 (Moved down)

panel #9 (removed)

panel #10 (removed

panel #11 (removed)

*Left side MLP panel numbers:*











*Left side MLP 1st & 2nd reflections:*











*Right side MLP 1st & 2nd reflections:*











*Ceiling reflections:*











*Here is my surround speakers, so no absorbtion panel at 1st reflection?:*


----------



## NicksHitachi




> Quote:
> Originally Posted by *robc1976* /forum/post/21132458
> 
> 
> Okay guys, I would like some advice if possible...I know I am using foam and it is not the best but I am getting much better in about 2-3 months and would just like to make the foam work the best it can for the time being. In the pics below I have a pic of panels numbered so it is easier to understand what you are taking about if you guys suggest I move a panel, remove ECT, below are the pics of the left side of MLP (one that needs help the most LOL!!) and Right side MLP and both 1st and 2nd reflections.....any suggestions are VERY much appreciated on placement, taking a panel down wich I am sure will be suggested. I noticed on the right side of MLP alll 1st and 2nd refections are on 2 panels.
> 
> *From what I see on left side:*
> 
> 
> panel #1 (removed)
> 
> panel #2 (Moved up)
> 
> panel #3 (Moved down)
> 
> panel #4 (Removed)
> 
> panel #5 (Removed)
> 
> panel #6 (Moved down)
> 
> panel #7 (Removed)
> 
> panel #8 (Moved down)
> 
> panel #9 (removed)
> 
> panel #10 (removed
> 
> panel #11 (removed)
> 
> *Left side MLP panel numbers:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Left side MLP 1st & 2nd reflections:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Right side MLP 1st & 2nd reflections:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Ceiling reflections:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Here is my surround speakers, so no absorbtion panel at 1st reflection?:*



I'm amazed you've got this far without an spl meter your setup looks like your serious abuot this hobby. IMO if your serious skip the spl meter, buy a calibrated mic from dayton audio for $40 and external sound card for computer $30 and down load REW(free) and do realtime analysis of the changes your making. Dialing in a sub is one thing with a spl meter, but room treatments will require at least REW IMO. You won't be sorry.


Your room is a little complex for me to comment much, im sure some on here could though. I would try better to a cover the level of the tweeter at reflection points and seal off the adjacent area or make sure that area is completely covered in foam IMO.


----------



## localhost127

your best bet is to get a $50 mic, pre-amp, and a free copy of Room EQ Wizard - and use the Envelope Time Curve (ETC) response to generate plots (*one speaker at a time!)* that will detail to you how the impulse energy impedes the listening position (gain with respect to time).


from there, you can hunt down what boundary sources are responsible for the early reflections - and treat as required (and then remeasure to verify the reflection was attenuated in gain below the human detection threshold).


----------



## robc1976




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21132726
> 
> 
> I'm amazed you've got this far without an spl meter your setup looks like your serious abuot this hobby. IMO if your serious skip the spl meter, buy a calibrated mic from dayton audio for $40 and external sound card for computer $30 and down load REW(free) and do realtime analysis of the changes your making. Dialing in a sub is one thing with a spl meter, but room treatments will require at least REW IMO. You won't be sorry.
> 
> 
> Your room is a little complex for me to comment much, im sure some on here could though. I would try better to a cover the level of the tweeter at reflection points and seal off the adjacent area or make sure that area is completely covered in foam IMO.



I have always wanteed to have a nice system and it is fun building one like this, my dad has the same speakers also...I am getting REW for sure and the 302B...have no idea how to use this stuff but that is the fun part...learning. I have learned more on this board than anywhere....some pretty awesome people here who are nice enough to share there knowledge!!


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21132971
> 
> 
> your best bet is to get a $50 mic, pre-amp, and a free copy of Room EQ Wizard - and use the Envelope Time Curve (ETC) response to generate plots (*one speaker at a time!)* that will detail to you how the impulse energy impedes the listening position (gain with respect to time).
> 
> 
> from there, you can hunt down what boundary sources are responsible for the early reflections - and treat as required (and then remeasure to verify the reflection was attenuated in gain below the human detection threshold).



I will for sure do this, also since you know youir products what do you think of these bass traps? I am going to start replacing the foam piece by piece and thought to start with the traps first. Only issue I see is that the are a flat panel but it says thyey can be angled in the corner and are up to 60% better than the best foam. Another issue is they come in 4' X 2' pieces, well I need 7' and 6' pieces?

*244 bass trap:*

http://gikacoustics.com/gik_244.html 

*Tri-trap (this looks like a bass trap because it fills the entire corner but it say it also absorbs a lot of HF...is that a good thing?*

http://gikacoustics.com/gik_tri_trap.html 

*242 panel for 1st & 2nd reflections:*

http://gikacoustics.com/gik_242.html


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21134021
> 
> 
> I will for sure do this, also since you know youir products what do you think of these bass traps? I am going to start replacing the foam piece by piece and thought to start with the traps first. Only issue I see is that the are a flat panel but it says thyey can be angled in the corner and are up to 60% better than the best foam. Another issue is they come in 4' X 2' pieces, well I need 7' and 6' pieces?
> 
> *244 bass trap:*
> 
> http://gikacoustics.com/gik_244.html
> 
> *Tri-trap (this looks like a bass trap because it fills the entire corner but it say it also absorbs a lot of HF...is that a good thing?*
> 
> http://gikacoustics.com/gik_tri_trap.html
> 
> *242 panel for 1st & 2nd reflections:*
> 
> http://gikacoustics.com/gik_242.html



specular energy is generally (dependent upon room boundaries) considered ~300hz and up. below this is the modal region where we absorb with corner bass traps.


4" OC703 with 2-4" air-gap will be sufficient for the specular broadband absorbers (for early reflection points).


ive already recommended DIY corner traps (deep/thick) made out of cheap, pink fluffy insulation.


i would not recommend the OC703 bass traps unless you have real estate constraints. if you need to see a company selling such a bass trap for "validation" of their performance (re: the pink fluffy), then i suggest you look at the GIK sofft bass traps ... as I believe those are made with lower gas flow resistivity material than their OC703 bass traps.


if you have questions about their products, i dont know why you are asking here... you should be contacting them. the service/support/convenience/etc is part of the premium you pay for retail-made products vs DIY.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21134212
> 
> 
> specular energy is generally (dependent upon room boundaries) considered ~300hz and up. below this is the modal region where we absorb with corner bass traps.
> 
> 
> 4" OC703 with 2-4" air-gap will be sufficient for the specular broadband absorbers (for early reflection points).
> 
> 
> ive already recommended DIY corner traps (deep/thick) made out of cheap, pink fluffy insulation.
> 
> 
> i would not recommend the OC703 bass traps unless you have real estate constraints. if you need to see a company selling such a bass trap for "validation" of their performance (re: the pink fluffy), then i suggest you look at the GIK sofft bass traps ... as I believe those are made with lower gas flow resistivity material than their OC703 bass traps.
> 
> 
> if you have questions about their products, i dont know why you are asking here... you should be contacting them. the service/support/convenience/etc is part of the premium you pay for retail-made products vs DIY.



Thanks, I actually would rather have somone familar with the products opinion that someone who sells it.


----------



## robc1976

Just to clarify, most absorbtion should be placed in the front soundstage? Because after my seats there is no absorbtion. Also on the surrounds there should be no absorbtion or diffusion on the first reflection point?


----------



## robc1976

Am I wrong in saying that panel #7-#11 are useless because there are no reflection points on them and I could move the other panels a bit (up down) to better cover the reflection points? Also I failed to mention that on the bared window there is 1/8th" plexiglass on it...would this cause a issue if I decided to remove some of the panels?


----------



## NicksHitachi




> Quote:
> Originally Posted by *robc1976* /forum/post/21137049
> 
> 
> Just to clarify, most absorbtion should be placed in the front soundstage? Because after my seats there is no absorbtion. Also on the surrounds there should be no absorbtion or diffusion on the first reflection point?



First off I assume your using a mirror to pinpoint your reflection points. I think somewere online there is a reflection point calculator which graphicallly outputs where the reflection energy is in the room if you put your dimensions in there. Pinpoint reflection points and cover them 2'X4" for example for the mains starting at tweeter level.


I think most prefer diffusion at and behind the listening position and in some other instances prior to listening position.


However instead of a lack of treatment, I prefer absorption on the back wall fror mains reflection, and anywhere surrounds are close to a boundary ie in your case side wall on surround. It is said that diffusion is preferred here IIRC.


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21137388
> 
> 
> First off I assume your using a mirror to pinpoint your reflection points. I think somewere online there is a reflection point calculator which graphicallly outputs where the reflection energy is in the room if you put your dimensions in there. Pinpoint reflection points and cover them 2'X4" for example for the mains starting at *tweeter level.*



no - if you're using the 'mirror-trick' to quickly identify first-reflection points (which may or may not be early reflection points) on major boundaries, you want to look for the speaker's *acoustic center*, not the tweeter. the bulk of the energy content is in the low-mid specular region, not the HF/UHF radiating from the tweeter.


and you should be using the Envelope Time Curve (ETC) response to identify how energy impedes the listening position (gain and time-delta with respect to the original signal).


the 'mirror-trick' is a very rudimentary way of finding reflection points on major boundaries, but it is not a solution as it doesnt' detail you anything regarding the energy content or time arrival.


----------



## robc1976




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21137388
> 
> 
> First off I assume your using a mirror to pinpoint your reflection points. I think somewere online there is a reflection point calculator which graphicallly outputs where the reflection energy is in the room if you put your dimensions in there. Pinpoint reflection points and cover them 2'X4" for example for the mains starting at tweeter level.
> 
> 
> I think most prefer diffusion at and behind the listening position and in some other instances prior to listening position.
> 
> 
> However instead of a lack of treatment, I prefer absorption on the back wall fror mains reflection, and anywhere surrounds are close to a boundary ie in your case side wall on surround. It is said that diffusion is preferred here IIRC.



I am using the mirror trick and it works pretty good I must admit, akso did that on the ceiling and I used the half way point measurement. I do have 4 diffusors on the back wall, I am 12 ft from the rear of the room. I have noticed bthat when I get the new thicker panels my speakers will have to be pulled foward because the wides are close the the wall....I know that sucks but it works. My question is how far from the absorbtion can the speaker be...it would be behind the speaker about 3-4" (I am getting the 2' X 4' panels.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21137507
> 
> 
> no - if you're using the 'mirror-trick' to quickly identify first-reflection points (which may or may not be early reflection points) on major boundaries, you want to look for the speaker's *acoustic center*, not the tweeter. the bulk of the energy content is in the low-mid specular region, not the HF/UHF radiating from the tweeter.



Is it safe to say that if I treat from the middle of the speaker and 12" above the tweeter it is covered, my question is how much material is needed for the 1st reflection point? I am guessing it depends on distance. Are the 2nd redflection points as important? I am asking because on my pics above all the 1st and 2nd reflections on the right side of MLP are on 2 squares but I have more material than that to be safe. On the leeft side the 2nd reflections SUCK...one is on a door jam and one close to a door jam, the 1st reflections are better.


----------



## robc1976




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21137388
> 
> 
> anywhere surrounds are close to a boundary ie in your case side wall on surround. It is said that diffusion is preferred here IIRC.



So diffusion on the 1st reflection points of the surrounds?


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21139280
> 
> 
> I am using the mirror trick and it works pretty good I must admit,



so you completely ignored my previous commentary?


tell me, then - what did the mirror tell you is the gain and arrival time of the early reflections (per speaker)?


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21139309
> 
> 
> Is it safe to say that if I treat from the middle of the speaker and 12" above the tweeter it is covered, my question is how much material is needed for the 1st reflection point?



what's the point of replying to you if you completely ignore the commentary. this was addressed above.


----------



## Jay5298

I haven't looked at this thread for a while. It seems that the thoughts about how to build corner bass traps have changed, at least from some points of view. I built may bass traps based on Ethan from Realtraps information. He did tests using OC703 and OC705 and concluded that OC705 was the best for absorbing low frequencies. I built my corner traps using 4" thick OC705 from floor to ceiling in all four corners and put the FRK facing on them as well. Now I'm reading that pink "fluffy" insulation is best?


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21139375
> 
> 
> so you completely ignored my previous commentary?
> 
> 
> tell me, then - what did the mirror tell you is the gain and arrival time of the early reflections (per speaker)?



Woah!!! I am not ignoring ANYTHING you have said?? I just don't understand the commentary. all I said is the mirror gave me a pretty good indication where it was....if I was ignoring it I would not have copied it and put it in a notepad....you have to realize this is a bit greek yto me so i have to ask questions to get a grasp of it.


Sorry you took it that way.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21139375
> 
> 
> so you completely ignored my previous commentary?
> 
> 
> tell me, then - what did the mirror tell you is the gain and arrival time of the early reflections (per speaker)?



Nothing, it would only show placement?


----------



## robc1976

Localhost:


You said "Find the accoustic center" so I guessed where it was?? How is that ignoring you??? I honestly dont get it







I would have thought you would have explained it...but that is just me.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21139375
> 
> 
> so you completely ignored my previous commentary?
> 
> 
> tell me, then - what did the mirror tell you is the gain and arrival time of the early reflections (per speaker)?



I am still going to use softwaye and tools as you suggest once I get the higher grade stuff, just not with the foam.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21139901
> 
> 
> Woah!!! I am not ignoring ANYTHING you have said?? I just don't understand the commentary. all I said is the mirror gave me a pretty good indication where it was....if I was ignoring it I would not have copied it and put it in a notepad....you have to realize this is a bit greek yto me so i have to ask questions to get a grasp of it.
> 
> 
> Sorry you took it that way.



ok - i thought you glossed over all of the measurement text and still were insisting the mirror is acceptable. no worries.


yes - and that's fine...just understand the limitations of the mirror. it gives an approximate location only! but what's really important is the gain and arrival time with respect to the original signal.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21139967
> 
> 
> ok - i thought you glossed over all of the measurement text and still were insisting the mirror is acceptable. no worries.
> 
> 
> yes - and that's fine...just understand the limitations of the mirror. it gives an approximate location only! but what's really important is the gain and arrival time with respect to the original signal.



I agree with you and actually like your attention to detail.....that is what IMHO will give you the best sound. The mirror I can see the limitaions because you could move your head foward 1/2" and it is a differen't spot.







i have a lot to learn and must say I like this part of the hobby best because I was going to upgrade my speakers but I think with tretments it will give you better results that a smalll upgrade in speakers and that is with this cheap foam, cant imagine what highend or DIY stuff does.


----------



## pepar




> Quote:
> Originally Posted by *robc1976* /forum/post/21140070
> 
> 
> I agree with you and actually like your attention to detail.....that is what IMHO will give you the best sound. The mirror I can see the limitaions because *you could move your head foward 1/2" and it is a differen't spot.
> 
> 
> 
> 
> 
> 
> 
> * i have a lot to learn and must say I like this part of the hobby best because I was going to upgrade my speakers but I think with tretments it will give you better results that a smalll upgrade in speakers and that is with this cheap foam, cant imagine what highend or DIY stuff does.



The idea is to do all three front speakers to all listening positions. Floor, ceiling and left front and right front walls. Also, the rear wall is a first reflection point ... as is the wall behind the speakers ... which you have "covered."


Size the treatments big enough so that moving a head a few inches won't be "outside" the absorber.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21140201
> 
> 
> The idea is to do all three front speakers to all listening positions. Floor, ceiling and left front and right front walls. Also, the rear wall is a first reflection point ... as is the wall behind the speakers ... which you have "covered."
> 
> 
> Size the treatments big enough so that moving a head a few inches won't be "outside" the absorber.



Thank you my friend!


----------



## localhost127




> Quote:
> Originally Posted by *Jay5298* /forum/post/21139766
> 
> 
> I haven't looked at this thread for a while. It seems that the thoughts about how to build corner bass traps have changed, at least from some points of view. I built may bass traps based on Ethan from Realtraps information. He did tests using OC703 and OC705 and concluded that OC705 was the best for absorbing low frequencies. I built my corner traps using 4" thick OC705 from floor to ceiling in all four corners and put the FRK facing on them as well. Now I'm reading that pink "fluffy" insulation is best?



it's always been that way.


deep traps are required due to the nature that they are velocity-based absorbers.


however, the deeper the trap, the lower gas flow-resistivity material you will want to use.


----------



## CruelInventions




> Quote:
> Originally Posted by *Jay5298* /forum/post/21139766
> 
> 
> I haven't looked at this thread for a while. It seems that the thoughts about how to build corner bass traps have changed, at least from some points of view. I built may bass traps based on Ethan from Realtraps information. He did tests using OC703 and OC705 and concluded that OC705 was the best for absorbing low frequencies. I built my corner traps using 4" thick OC705 from floor to ceiling in all four corners and put the FRK facing on them as well. Now I'm reading that pink "fluffy" insulation is best?



I am thinking that Ethan's measurements were based upon the 2' by 4', 4" to 6" thick variety of corner bass trap. Not the triangle stacking method of corner bass trap. So based upon localhosts post immediately above, it appears that both materials can be valid, depending upon which style of trap you go with. OC705 for the former style of corner bass trapping but better to use the lighter fluffy stuff for the much deeper corner bass traps, such as the triangle wedge designs.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *CruelInventions* /forum/post/21142329
> 
> 
> I am thinking that Ethan's measurements were based upon the 2' by 4', 4" to 6" thick variety of corner bass trap. Not the triangle stacking method of corner bass trap. So based upon localhosts post immediately above, it appears that both materials can be valid, depending upon which style of trap you go with. OC705 for the former style of corner bass trapping but better to use the lighter fluffy stuff for the much deeper corner bass traps, such as the triangle wedge designs.



I haven't been following closly either but if you are saying that the Pink fuffy insulation is yeilding similar results to the semi rigid OC705 or the Linacoustic when used as a corner (triangle) bass trap, your comments fly in the face of everything I have read.


Very interesting!


----------



## pepar

Me,too. But he might be compensating with size.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/21142603
> 
> 
> I haven't been following closly either but if you are saying that the Pink fuffy insulation is yeilding similar results to the semi rigid OC705 or the Linacoustic when used as a corner (triangle) bass trap, your comments fly in the face of everything I have read.
> 
> 
> Very interesting!



Actually better, not just similar, seems to be the now prevailing wisdom over at gearsluz - here for example:

http://www.gearslutz.com/board/bass-...ner-traps.html 


I assume there are some measurements that have been done to back this up, but I haven't run across them yet. Anyway, I've already built my Roxul AFB SuperChunks, and have no intent to tear them out!










Edit: also not sure whether the comparison is based on equal depths of fluffy vs rigid insulation.


----------



## Dan Woodruff




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21142664
> 
> 
> Actually better, not just similar, seems to be the now prevailing wisdom over at gearsluz - here for example:
> 
> http://www.gearslutz.com/board/bass-...ner-traps.html
> 
> 
> I assume there are some measurements that have been done to back this up, but I haven't run across them yet. Anyway, I've already built my Roxul AFB SuperChunks, and have no intent to tear them out!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Edit: also not sure whether the comparison is based on equal depths of fluffy vs rigid insulation.



To quote a well known leader in the industry and in a word . . . "Bullsh*t".


----------



## Dan Woodruff

To qualify . . . in that thread you gave a link to, they are discussing insulation to place behind a bass trap similar to the traps Ethan sells.


I don't believe for a second that fluffy pink insulation will work as well as a stand alone trap.


----------



## nickbuol

Yeah, that article seems to talk about taking fluffy stuff and packing it as tightly as possible to make it more dense, and then putting it behind ones' corner straddling bass traps, not making bass traps solely out of the fluffy stuff (which again, isn't so "fluffy" if it is compacted)...


----------



## fotto

I'd like to understand the close to 12" air gap that is entered into the spreadsheet localhost shows. If you have traditional superchunk construction going into the corner, where/what is the 12" of "airgap"? The spreadsheet doesn't really give me that answer.


Also, is this really modeled for a CORNER bass trap or is it intended for a single flat surface model?


----------



## localhost127




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/21142752
> 
> 
> To qualify . . . in that thread you gave a link to, they are discussing insulation to place behind a bass trap similar to the traps Ethan sells.
> 
> 
> I don't believe for a second that fluffy pink insulation will work as well as a stand alone trap.



negative.

there is no benefit to mixing materials with differing acoustical impedance.


this includes material-air-material impedance changes.


this is simple physics - and we all know what happens when there is a change in impedance.


porous insulation is a velocity-based absorber. it needs to be placed at areas of high particle velocity in order to be effective.


as you create thicker and thicker traps, you use a material with lower gas flow resistivity.


even the standard 34"faced superchunk triangles will perform better with lower flow-resistivity material (~5000rayls/m GFR).

http://www.afmg.eu/index.php/read-ne...-released.html 



http://imgur.com/buwNv.gif%5B/IMG%5D


----------



## localhost127




> Quote:
> Originally Posted by *fotto* /forum/post/21143600
> 
> 
> I'd like to understand the close to 12" air gap that is entered into the spreadsheet localhost shows. If you have traditional superchunk construction going into the corner, where/what is the 12" of "airgap"? The spreadsheet doesn't really give me that answer.
> 
> 
> Also, is this really modeled for a CORNER bass trap or is it intended for a single flat surface model?



corner trap.


although, it is best to mount the pink fluffy vertically - as horizontal corner chunks piled on top of each other will (via gravity), will compress the layers at the bottom.


you can cut thin strips and hang vertically, and each layer will be wider and wider.


it is especially important to keep the orientation of the insulation the same



like this:



http://imgur.com/MGsyj.png%5B/IMG%5D


----------



## localhost127




> Quote:
> Originally Posted by *Dan Woodruff* /forum/post/21142752
> 
> 
> I don't believe for a second that fluffy pink insulation will work as well as a stand alone trap.



and why is that, exactly?


----------



## fotto




> Quote:
> Originally Posted by *localhost127* /forum/post/21143902
> 
> 
> corner trap.
> 
> 
> although, it is best to mount the pink fluffy vertically - as horizontal corner chunks piled on top of each other will (via gravity), will compress the layers at the bottom.
> 
> 
> you can cut thin strips and hang vertically, and each layer will be wider and wider.
> 
> 
> it is especially important to keep the orientation of the insulation the same
> 
> 
> 
> like this:
> 
> 
> 
> http://imgur.com/MGsyj.png%5B/IMG%5D



I still don't understand where the air gap is, if you have either 703/705 triangle filling the corner, or fluffy pink filling the corner, I would say there is no air gap. If you have a wall panel with 2" of free space between the wall and the insulation or whatever the material, then that's a 2" air gap right?


Back to the corner, if you have material stuffed into the corner, then where's the gap as is called out in the spreadsheet?


----------



## localhost127




> Quote:
> Originally Posted by *fotto* /forum/post/21143947
> 
> 
> I still don't understand where the air gap is, if you have either 703/705 triangle filling the corner, or fluffy pink filling the corner, I would say there is no air gap. If you have a wall panel with 2" of free space between the wall and the insulation or whatever the material, then that's a 2" air gap right?
> 
> 
> Back to the corner, if you have material stuffed into the corner, then where's the gap as is called out in the spreadsheet?



there is no gap in that example - it is fine to fill the entire cavity with pink fluffy (granted that it is loosely uncompressed).


----------



## Dan Woodruff




> Quote:
> Originally Posted by *localhost127* /forum/post/21143889
> 
> 
> negative.
> 
> there is no benefit to mixing materials with differing acoustical impedance.
> 
> 
> this includes material-air-material impedance changes.
> 
> 
> this is simple physics - and we all know what happens when there is a change in impedance.
> 
> 
> porous insulation is a velocity-based absorber. it needs to be placed at areas of high particle velocity in order to be effective.
> 
> 
> as you create thicker and thicker traps, you use a material with lower gas flow resistivity.
> 
> 
> even the standard 34"faced superchunk triangles will perform better with lower flow-resistivity material (~5000rayls/m GFR).
> 
> http://www.afmg.eu/index.php/read-ne...-released.html
> 
> 
> 
> http://imgur.com/buwNv.gif%5B/IMG%5D



I suggest you go back and re-read that thread. It is discussing mixing materials.


Here is am image of what is being discussed and recommended in that thread. You will not see this in my theater.

http://www.gearslutz.com/board/attac...ce-photo-5.jpg


----------



## fotto




> Quote:
> Originally Posted by *localhost127* /forum/post/21128409
> 
> 
> most certainly not. but what else do you expect from herd-mentality. why does opinion matter with regards to basic physics?
> 
> 
> 
> 
> depends on thickness of trap, and spacing of the insulation is areas of higher particle velocity.
> 
> 
> 
> OC703 (16,500 rayls/m)
> 
> 
> http://imgur.com/u1QVB.png%5B/IMG%5D
> 
> 
> 
> pink fluffy (5000 rayls/m)
> 
> 
> http://imgur.com/I5LcQ.png%5B/IMG%5D





> Quote:
> Originally Posted by *localhost127* /forum/post/21143975
> 
> 
> there is no gap in that example - it is fine to fill the entire cavity with pink fluffy (granted that it is loosely uncompressed).



OK, I get it that there's no air gap in your example drawing. My question more pertains to the graph you presented above with comparison of 703 and regular insulation. I was under the impression you are making a comparison there for a corner trap....if so, then why is there an air gap of 12" included in the model?


----------



## orcarola25

So when we are talking Pink Fluffy, are we referring to R13, R19, or R30? Or does it even matter?


----------



## Dan Woodruff




> Quote:
> Originally Posted by *orcarola25* /forum/post/21144057
> 
> 
> So when we are talking Pink Fluffy, are we referring to R13, R19, or R30? Or does it even matter?



By the comments I have seen here (and in the other thread).... it doesn't seem to matter.


----------



## localhost127




> Quote:
> Originally Posted by *fotto* /forum/post/21144015
> 
> 
> OK, I get it that there's no air gap in your example drawing. My question more pertains to the graph you presented above with comparison of 703 and regular insulation. I was under the impression you are making a comparison there for a corner trap....if so, then why is there an air gap of 12" included in the model?



it was to detail how differing flow-resistivity values perform - not necessarily as a corner trap (eg, a rear wall trap).


oc703


http://imgur.com/nlLbc.png%5B/IMG%5D




pink


http://imgur.com/xExdJ.png%5B/IMG%5D


----------



## localhost127

robc - you are showing the biggest asset right in your photos - HUGE access to the corners within the room.


dont let any of the commentary here overwhelm you. if you're willing to put a little effort in, you'll accomplish real results. there's a fine community here, even if the recommendations may seem a little overwhelming at first.


while the thin absorption and shallow diffusers will most certainly make a 'difference' in sound in the room, the real importance is in the mid-lower specular region (where the bulk of the energy content is).


the goal is most certainly not to create a dead room with a high % of the room treated with (broadband specular) absorption. caveat that LF/bass modal absorption in small acoustical spaces - well, you can never have too much.


the fact that you are adamant and posting many follow-ups show you are at least interested in what's happening within your room. very cool. many post a simple question, become overwhelmed, and drop it. dont take the path of least resistance. there is an ultra-valuable community here that will sort you out.


----------



## localhost127

bookmark for later:
http://www.gearslutz.com/board/studi...er-v2-1-a.html 

http://www.avsforum.com/avs-vb/showt...7#post18486257


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21144876
> 
> 
> robc - you are showing the biggest asset right in your photos - HUGE access to the corners within the room.
> 
> 
> dont let any of the commentary here overwhelm you. if you're willing to put a little effort in, you'll accomplish real results. there's a fine community here, even if the recommendations may seem a little overwhelming at first.
> 
> 
> while the thin absorption and shallow diffusers will most certainly make a 'difference' in sound in the room, the real importance is in the mid-lower specular region (where the bulk of the energy content is).
> 
> 
> the goal is most certainly not to create a dead room with a high % of the room treated with (broadband specular) absorption. caveat that LF/bass modal absorption in small acoustical spaces - well, you can never have too much.
> 
> 
> the fact that you are adamant and posting many follow-ups show you are at least interested in what's happening within your room. very cool. many post a simple question, become overwhelmed, and drop it. dont take the path of least resistance. there is an ultra-valuable community here that will sort you out.



Than k you, If we did have people here like you, pepar it wouldn't be the same....your info and attemntion to detail is very admirable and the fact that you share your info is VERY respectable. I have a saying "Knowledge is NOT power unless you share it with others and you have!


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21144896
> 
> 
> bookmark for later:
> http://www.gearslutz.com/board/studi...er-v2-1-a.html
> 
> http://www.avsforum.com/avs-vb/showt...7#post18486257



Bookmarked and put in my notepad!


----------



## orcarola25




> Quote:
> Originally Posted by *robc1976* /forum/post/0
> 
> 
> Than k you, If we did have people here like you, pepar it wouldn't be the same....your info and attemntion to detail is very admirable and the fact that you share your info is VERY respectable. I have a saying "Knowledge is NOT power unless you share it with others and you have!



+1. Your willingness to share detailed information over and over again is very valuable.

Much appreciated!!!


----------



## robc1976




> Quote:
> Originally Posted by *orcarola25* /forum/post/21144966
> 
> 
> +1. Your willingness to share detailed information over and over again is very valuable.
> 
> Much appreciated!!!



Those 2 guys and others have taught me a lot in the last couple of days....great guys!


----------



## yacht422

big request: i remember earlier in the year that someone posted 'plans' for the building of an elevated rear seating platform, but treating it as a bass absorber, complete with proper hole diameters and locations.

it will take me a week to find it again, which, if no one can link it to me, i will do.

just trying to save time.

thanking in advance,

walt


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *yacht422* /forum/post/21175633
> 
> 
> big request: i remember earlier in the year that someone posted 'plans' for the building of an elevated rear seating platform, but treating it as a bass absorber, complete with proper hole diameters and locations.
> 
> it will take me a week to find it again, which, if no one can link it to me, i will do.
> 
> just trying to save time.
> 
> thanking in advance,
> 
> walt



this?

http://www.avsforum.com/avs-vb/showthread.php?t=1103345


----------



## pepar

That thread went 8 posts and then died almost 3 years ago. I'd PM the member for folloow-up info to see whether or not it made any difference and if it was worth all the work.


----------



## longshorejl

Let me know what you find out. I'm doing riser build in a couple weeks. I would love to get some details on how to make it into a broad band bass trap. I have roughly the same space as that thread.


----------



## mtbdudex




> Quote:
> Originally Posted by *yacht422* /forum/post/21175633
> 
> 
> big request: i remember earlier in the year that someone posted 'plans' for the building of an elevated rear seating platform, but treating it as a bass absorber, complete with proper hole diameters and locations.
> 
> it will take me a week to find it again, which, if no one can link it to me, i will do.
> 
> just trying to save time.
> 
> thanking in advance,
> 
> walt





> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21176128
> 
> 
> this?
> 
> http://www.avsforum.com/avs-vb/showthread.php?t=1103345



Look at this recent thread, 2nd page.
http://www.avsforum.com/avs-vb/showt...t=riser&page=2


----------



## yacht422




> Quote:
> Originally Posted by *yacht422* /forum/post/21175633
> 
> 
> big request: i remember earlier in the year that someone posted 'plans' for the building of an elevated rear seating platform, but treating it as a bass absorber, complete with proper hole diameters and locations.
> 
> it will take me a week to find it again, which, if no one can link it to me, i will do.
> 
> just trying to save time.
> 
> thanking in advance,
> 
> walt


as i hoped, much good advice has been provided. given that i'm 70, and math was never my strong suite, the book referenced by local host will not fill my shelves (although a well thumbed 'Toole', is there). So, again my thanks, and a broadband unit seems to be the best next step.

Walt


----------



## HopefulFred




> Quote:
> Originally Posted by *yacht422* /forum/post/21180807
> 
> 
> math was never my strong suite



Just thought I would add a reference for those of us who are not mathemagicians. Hyperphysics is a website written and maintained by one of my former professors. While he is a physicist (thus a mathemagician), his website is largely conceptual, and written so that undergraduates and even high school students can get a lot out of it. This is, of course, no guide for design and construction, but can help to fully conceptualize the major variables that work to make a Helmholtz resonator. (At least, I think so...)

http://hyperphysics.phy-astr.gsu.edu...es/cavity.html 


Fred


----------



## yacht422

thx for the link: as you know, there is a LOT of information there!

walt


----------



## secondhander

Hello!


Would anyone have suggestions on what a total newb to acoustics should first consider for treating a small dedicated theater? Is there any one thing that every dedicated room should have that would drastically improve audio to a non audiophile? I have yet to run any real tests at this point since I'm not at that stage, but my room is a bit of an odd shape with a false wall being built for an AT screen.


My plan was to worry about this after I get the guts of the theater together but I'm just wondering if I should take anything in to consideration now? My build thread has layouts to show the room dimensions if it helps. The wall behind the screen is the foundation for a bay window above, so it has two 45 degree walls and it's concrete behind the drywall. We are not worrying about soundproofing the room, it's just my wife, kid and myself but it's a long narrow room with a riser at the back and I wouldn't want sounds echoing heh.


For example, is insulating a riser a necessity?


Thanks!


----------



## Felgar




> Quote:
> Originally Posted by *localhost127* /forum/post/21128374
> 
> 
> cheap, pink fluffy attic insulation (uncompressed).
> 
> 
> gas flow resistivity value of the porous material is what's important. 34" faced superchunks of pink fluffy (or larger, if you can do it). UNCOMPRESSED. you will need horizontal supports every few feet such that the layers at the top do not compress the layers at the bottom.



Are there measurements generated and available that compare something more rigid like 703 against uncompressed fluffy pink against something like roxul safe 'n sound? For my 34" superchunks I was going to use Safe n Sound but obviously won't if fluffy is more effective. Shelving would provide a place to attach fabric as well so I'm not against it.


----------



## stockmonkey2000




> Quote:
> Originally Posted by *Felgar* /forum/post/21190997
> 
> 
> Are there measurements generated and available that compare something more rigid like 703 against uncompressed fluffy pink against something like roxul safe 'n sound? For my 34" superchunks I was going to use Safe n Sound but obviously won't if fluffy is more effective. Shelving would provide a place to attach fabric as well so I'm not against it.



I'm curious about this too. From what I have seen so far, all this gas flow resistivity talk is coming from the Chris Whealy program. I'm willing to give it the benefit of the doubt, but is there any real world testing that bears out the better performance of the loosely packed fluffy insulation?


----------



## stockmonkey2000

This article below mentions on page 5 when discussing gas flow resistivity that low flow resistivity materials are good for high frequencies and high flow resistivity materials are better for low frequencies.

http://www.universalaet.com/en/docs/...fle-design.pdf 


This seems to be verified by comparing the absorption characteristics on Bob golds website. Denser materials seem to have more absorption at lower frequencies than the less dense materials. I know it is just one article, but it does support the current standard practices.


----------



## Felgar




> Quote:
> Originally Posted by *stockmonkey2000* /forum/post/21191439
> 
> 
> This article below mentions on page 5 when discussing gas flow resistivity that low flow resistivity materials are good for high frequencies and high flow resistivity materials are better for low frequencies.
> 
> http://www.universalaet.com/en/docs/...fle-design.pdf
> 
> 
> This seems to be verified by comparing the absorption characteristics on Bob golds website. Denser materials seem to have more absorption at lower frequencies than the less dense materials. I know it is just one article, but it does support the current standard practices.



However the assertion that fluffy pink (very low flow resistivity) is best for a 34" face superchunk would basically be in direct contradiction to what you've just said. By my understanding, as depth increases, flow resistivity must decrease. So a superchunk being very deep, needs low flow resistivity. I can see that from an intuitive perspective; if flow is too resisted the sound wave will reflect off the surface rather than penetrate and be absorbed. Not sure if that's a reasonable explanation but it "seems" plausible.


----------



## robc1976

figured I would post some pics of some traetments I have redone.

*Here is the foam I had with all reflection points "Left side MLP"*











*GIK suggested 3 panels on this side and the farthest panel is not touching the "tri-trap" although it looks like it LOL!!*











*Here is the foam I had with all reflection points "right side MLP"*










*GIK suggested 3 panels on this side also.*











*Here is the Tr-trap in the corner, I have 2 tops coming also that will stack on these full size ones and will extend it to the top.*










*Here is the foam I have on the ceiling with reflection points (all 3 seats) and I have 6 242 panels on the way to put in place of the foam.*











So far the bass has improved dramitaclly and the detail has also increased dramitacly over the foam.


----------



## pepar

Wow, just ... wow.


----------



## fotto




> Quote:
> Originally Posted by *robc1976* /forum/post/21191872
> 
> 
> figured I would post some pics of some traetments I have redone.
> 
> 
> So far the bass has improved dramitaclly and the detail has also increased dramitacly over the foam.



Would you mind commenting on what the panels left/right wall are made of (material, depth etc.)?


I'll bet you'll get some additional improvement when you fill in your corner traps as well.


----------



## robc1976




> Quote:
> Originally Posted by *fotto* /forum/post/21192010
> 
> 
> Would you mind commenting on what the panels left/right wall are made of (material, depth etc.)?
> 
> 
> I'll bet you'll get some additional improvement when you fill in your corner traps as well.



I think the let side of MLP as 1 to many panels but it is just to make sure.

*Here they are:*

http://gikacoustics.com/gik_242.html


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21191962
> 
> 
> Wow, just ... wow.



There was a lot of curse words used in getting those reflection points...never realized how many there where...I was only doing 1 seat before LOL!!


----------



## pepar

You should have made a video. Timelapsed it would have been cool.


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21192518
> 
> 
> You should have made a video. Timelapsed it would have been cool.
> 
> 
> Jeff



ROFLMAO!!! I am lucky I have a cool wife!! By the end she wanted to kill me though


----------



## yacht422

a point of clarification, if you please.

re: first reflections;

is there ANY advantage of having 2" rfg, followed with a 2"air gap, followed by 2" of rfg, and then either the wall or an additional air gap, TBD?

thx

walt


----------



## Felgar

The air gap allows the absorbing material to be located in a position where the velocity of the wavelength is higher, so the positive effect of the air gap is to relocate the material away from the wall where there is zero velocity (and therefore where no absorbtion can occur). The air itself isn't helping the absorbtion; the new position of the fiberglass is what's helping.


Therefore, instead of the alternating gap design you've proposed, your most effective use of a panel of that depth would be 4" rigid fiberglass over a 2" air gap, or even better over a 4" air gap.


----------



## jgemdoc

excellent info thanks


----------



## localhost127




> Quote:
> Originally Posted by *stockmonkey2000* /forum/post/21191263
> 
> 
> I'm curious about this too. From what I have seen so far, all this gas flow resistivity talk is coming from the Chris Whealy program. I



those calculations and formulas came from:
http://www.amazon.com/Acoustic-Absor.../dp/B001Y35IHW 


and you can look into:
http://soundflow.afmg.eu/


----------



## pepar




> Quote:
> Originally Posted by *Felgar* /forum/post/21195207
> 
> 
> The air gap allows the absorbing material to be located in a position where the velocity of the wavelength is higher, so the positive effect of the air gap is to relocate the material away from the wall where there is zero velocity (and therefore where no absorbtion can occur). The air itself isn't helping the absorbtion; the new position of the fiberglass is what's helping.
> 
> 
> Therefore, instead of the alternating gap design you've proposed, your most effective use of a panel of that depth would be 4" rigid fiberglass over a 2" air gap, or even better over a 4" air gap.



This enhancement depends on the back of the panel being open, right? A plywood-backed panel would not benefit from this.


Jeff


----------



## Felgar




> Quote:
> Originally Posted by *pepar* /forum/post/21198382
> 
> 
> This enhancement depends on the back of the panel being open, right? A plywood-backed panel would not benefit from this.



My assumption would be that the air gap would be between the panel backing and the insulation, which makes the backing against the wall. With the backing against the wall, it's just acting as more wall, wouldn't you say? Maybe not quite because it'll be less rigid but for the most part, I would envision the back panel acting as part of the wall. If you were thinking insulation, then back panel, then gap, then wall I totally agree that wouldn't make sense.


----------



## pepar

My understanding is that the gap works by placing the absorption away from the wall where the particle velocity is zero to a point where the particles are moving ... and can be impeded. For this to work, the sound must travel through the panel and strike the wall. If the panel has a plywood back, then THAT is the "wall" and nothing is gained. Plus the open-back design allow the absorber to "absorb" the sound "coming and going."


----------



## FOH




> Quote:
> Originally Posted by *robc1976* /forum/post/21191872
> 
> 
> So far the bass has improved dramitaclly and the detail has also increased dramitacly over the foam.



Nice results, good lookin' out.


----------



## Felgar

We're agreeing Pepar -if there's a back panel, it should be against the wall and not against the absorption; when built correctly the air gap would be between the back panel and the absorption.


----------



## pepar




> Quote:
> Originally Posted by *Felgar* /forum/post/21199344
> 
> 
> We're agreeing Pepar -if there's a back panel, it should be against the wall and not against the absorption; when built correctly the air gap would be between the back panel and the absorption.



Depending what the backing is made of, there might be some diaphramatic action that could provide some additional trapping. However, resonator-type traps are designed from the ground up and this would be accidental if at all.


So, yeah, ...










Jeff


----------



## robc1976

Here are my GIK "back of panel about a 2" gap...total thickness with gap is about 4"+.


----------



## robc1976

Wanted some opinions on this, I was going to put 6 242 panels on my ceiling for reflection points...any opinions.

*Here are the reflection points:*










*Here is where I would put the panels:*


----------



## mtbdudex




> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> 
> those calculations and formulas came from:
> http://www.amazon.com/Acoustic-Absor.../dp/B001Y35IHW
> 
> 
> and you can look into:
> http://soundflow.afmg.eu/



Have you "played" with the 30 day free trial of soundflow?
http://soundflow.afmg.eu/index.php/sf-downloads-en.html 


> Quote:
> Free Trial Version
> 
> 
> Register here for a time-limited copy of AFMG SoundFlow:
> AFMG SoundFlow 30-Days Trial





> Quote:
> SoundFlow Basic Features
> 
> 
> Simulation of absorption, reflection and transmission of sound by multi-layer structures
> 
> (limited to 4 layers in SoundFlow Basic)
> 
> Modeling of wall, floor and ceiling structures by specifying layer materials and thickness
> 
> Transmission calculations with open back or absorption calculations with rigid back termination
> 
> Calculations within the complete frequency range of 10 Hz to 20 kHz
> 
> Intuitive graphical user interface
> 
> Large, expandable database of standard materials divided into three types: absorbers, perforated panels and plates
> 
> Easy generation of new materials by altering existing ones or simply entering manufacturer data
> 
> Various common acoustic quantities such as ALPHAw, NRC, Rw and STC figures
> 
> Graphical display of frequency-dependant absorption and reflection coefficients and transmission loss
> 
> Adjustable smoothing, scaling of axes and frequency resolution in displays
> 
> Incident sound at adjustable angles or as a diffuse field
> 
> All calculations according to Bies
> 
> Support for both metrical and US Customary units
> 
> Export all data in editable and printable formats, such as RTF and PDF as well as to various bitmap formats, such as BMP and PNG





> Quote:
> SoundFlow Standard Features
> 
> 
> Simulation of absorption, reflection and transmission of sound by multi-layer structures
> 
> Modeling of wall, floor and ceiling structures by specifying layer materials and thickness
> 
> Transmission calculations with open back or absorption calculations with rigid back termination
> 
> Calculations within the complete frequency range of 10 Hz to 20 kHz
> 
> Intuitive graphical user interface
> 
> Large, expandable database of standard materials divided into three types: absorbers, perforated panels and plates
> 
> Easy generation of new materials by altering existing ones or simply entering manufacturer data
> 
> Various common acoustic quantities such as ALPHAw, NRC, Rw and STC figures
> 
> Graphical display of frequency-dependant absorption and reflection coefficients and transmission loss
> 
> Adjustable smoothing, scaling of axes and frequency resolution in displays
> 
> Incident sound at adjustable angles or as a diffuse field
> 
> Choice of numerous absorber models incl. ISO / DIN EN 12354, Mechel, Bies, Komatsu, Miki, Delany-Bazley etc.
> 
> Simultaneous examination of several structures
> 
> Useful overlay functions for comparison of all results
> 
> Support for both metrical and US Customary units
> 
> Direct export of EASE wall material files for usage of absorption coefficients in EASE and other simulations programs
> 
> Export all data in editable and printable formats, such as RTF and PDF as well as to various bitmap formats, such as BMP and PNG





> Quote:
> SoundFlow Pro Features
> 
> 
> Simulation of absorption, reflection and transmission of sound by multi-layer structures
> 
> Modeling of wall, floor and ceiling structures by specifying layer materials and thickness
> 
> Transmission calculations with open back or absorption calculations with rigid back termination
> 
> Calculations within the complete frequency range of 10 Hz to 20 kHz
> 
> Intuitive graphical user interface
> 
> Large, expandable database of standard materials divided into three types: absorbers, perforated panels and plates
> 
> Easy generation of new materials by altering existing ones or simply entering manufacturer data
> 
> Various common acoustic quantities such as ALPHAw, NRC, Rw and STC figures
> 
> Graphical display of frequency-dependant absorption and reflection coefficients and transmission loss as well as the complex input impedance, reflection and transmission factor
> 
> Display of the complex factors including the real and imaginary part as well as magnitude and phase
> 
> Adjustable smoothing, scaling of axes and frequency resolution in displays
> 
> Incident sound at adjustable angles or as a diffuse field
> 
> Choice of numerous absorber models incl. ISO / DIN EN 12354, Mechel, Bies, Komatsu, Miki, Delany-Bazley etc.
> 
> Simultaneous examination of several structures
> 
> Useful overlay functions for comparison of all results
> 
> Support for both metrical and US Customary units
> 
> Direct export of EASE wall material files for usage of absorption coefficients in EASE and other simulations programs
> 
> Export all data in editable and printable formats, such as RTF, PDF and simple text as well as to various bitmap formats, such as BMP and PNG





> Quote:
> AFMG SoundFlow
> 
> Product Version
> 
> 1 User Key Buy
> 
> SoundFlow Basic
> 
> 1.0 300,00 € net
> 
> SoundFlow Standard
> 
> 1.0 600,00 € net
> 
> SoundFlow Pro
> 
> 1.0 900,00 € net


----------



## localhost127

AFMG Reflex also has a free 30day trial - for those who 'think' their bookshelves are "diffusers" - they can model to see just how false that is.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21191872
> 
> 
> and the detail has also increased dramitacly over the foam.



are you willing to pursue and address the room's issues further?


it's very respected that you are following up with commentary for many of the passive readers in this thread.


have you acquired a mic ??


----------



## localhost127




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21202342
> 
> 
> Have you "played" with the 30 day free trial of soundflow?



if only such 'theory' of free 30-day trial would put to bed the thought of combining multiple types of materials (differing flow-resistivity, differing acoustical impedance) regarding porous bass traps in this forum


----------



## scl23enn4m3

Quick question: How detrimental would it be to compress Roxul SnS 3" to 2" in a frame? I'm not looking for a quantifiable answer, but would it somehow become less efficient than 1" OC703?


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21204823
> 
> 
> are you willing to pursue and address the room's issues further?
> 
> 
> it's very respected that you are following up with commentary for many of the passive readers in this thread.
> 
> 
> have you acquired a mic ??



I appreciate that, it is people like you that alow me to do this also..very respected. I want to go as far as I can with the room...I love accoustics because you literaly hear a difference from one change to the other. I am aquiring a mic and software in the next few days hopefully!


----------



## robc1976

I just cant believe how much of a improvment accostics actually do...my system before sounded like "crap" before this but most will n ever know this if it is not treated. It seems like I hear detail in movies I actually never heard before?? The bass hits so sharp and there are bass notes I NEVER noticed before also. I hope when I treat the ceiling reflection with panels and get rid of the "Crap foam" I hear a difference, I am sure it will.


----------



## robc1976

So am I correct in saying this,


Foam basically takes detail out of the sound and does nothing for the low end?? I am trying to convince my Dad to get rid of the foam also. It alsmost made the sound worse I think like the speakers where a bit mufflerd or something hard to really explain LOL!!


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21204940
> 
> 
> So am I correct in saying this,
> 
> 
> Foam basically takes detail out of the sound and does nothing for the low end?? I am trying to convince my Dad to get rid of the foam also. It alsmost made the sound worse I think like the speakers where a bit mufflerd or something hard to really explain LOL!!



it is not so much specifically the material in itself that is of concern, but whether it is utilized in such a way to address a specific problem.


this is not to say that 'foam' in itself is not effective - any material can be labeled ineffective if it is not used appropriately.


----------



## localhost127




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/21204848
> 
> 
> Quick question: How detrimental would it be to compress Roxul SnS 3" to 2" in a frame? I'm not looking for a quantifiable answer, but would it somehow become less efficient than 1" OC703?



unpredictable and no answer will be sufficient.


a specular reflection's gain is measured via the Envelope Time Curve (ETC) response - a tool that is included in the free measuring suite: Room EQ Wizard.


thin absorption which does not fully attenuate the reflection will simply filter the response at the listening position.


you can use the ETC response to measure the gain of a reflection and also the attenuation of the reflection when an 'absorber' has been implemented.


----------



## scl23enn4m3




> Quote:
> Originally Posted by *localhost127* /forum/post/21205090
> 
> 
> unpredictable and no answer will be sufficient.
> 
> 
> a specular reflection's gain is measured via the Envelope Time Curve (ETC) response - a tool that is included in the free measuring suite: Room EQ Wizard.
> 
> 
> thin absorption which does not fully attenuate the reflection will simply filter the response at the listening position.
> 
> 
> you can use the ETC response to measure the gain of a reflection and also the attenuation of the reflection when an 'absorber' has been implemented.



Thanks for the reply. I'm going to figure out how to use the software and interpret the results. Would you agree that the directions and forums at the software's website would be the best and most efficient place to start?


----------



## localhost127




> Quote:
> Originally Posted by *scl23enn4m3* /forum/post/21205234
> 
> 
> Thanks for the reply. I'm going to figure out how to use the software and interpret the results. Would you agree that the directions and forums at the software's website would be the best and most efficient place to start?



absolutely.

ignore the human nature to be completely overwhelmed when approaching a new subject.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21205013
> 
> 
> it is not so much specifically the material in itself that is of concern, but whether it is utilized in such a way to address a specific problem.
> 
> 
> this is not to say that 'foam' in itself is not effective - any material can be labeled ineffective if it is not used appropriately.



I see, totally makes sense!


----------



## robc1976

Got my 6 242 GIK panels today and mounted them on the drop ceiling (that was NOT fun!!) and thought I would post some before and after pics....I havent ran Audyssey on it yet but the sound is a lot more crisp and smooth sounding. 9.1 has a lot of reflection points LOL!!

*Here is the foam before:*











*Here are the new panels:*


----------



## pepar

Were your seats further back before?


----------



## localhost127

reflection points are not laser-dots like you have illustrated in your photos. it is with respect to wavelength size.


please obtain a mic and measure with the ETC so any guesswork can be eliminated. that is the only way to know for sure (the mirror-trick tells you only areas on large boundaries that may be incident of specular energy - it does not tell you anything about the gain of the reflection, the time arrival, or the attenuation once the absorber has been placed).


----------



## pepar

Do you think he is close to over-treating his space? Every space I've been in with all plaster/plasterboard walls and a non-acoustical ceiling has been horrid, and what he's done has immensely improved the sound.


If he wants to press on, then a calibrated mic and measuring software is needed. But maybe he's satisfied with the results and now just wants to enjoy it.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21214011
> 
> 
> Were your seats further back before?



Yep, they where at the 50% mark and i moved them to the 38% mark and that improved bass a ton and got MLP from out from under the air duct.


----------



## robc1976

Fedex on the way to deliver the tops to fill in the corners with the Tri-traps....hope they are exact (Had to get a custom size) because I have no margin for erorr LOL!!


----------



## pepar

Pick some bottom-heavy content and listen with it before and after the Tri-trap installation. My favorite is the opening battle sequence in Master and Commander Far Side of the World.


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21215029
> 
> 
> Yep, they where at the 50% mark and i moved them to the 38% mark and that improved bass a ton and got MLP from out from under the air duct.



why 38%?


there is a constant claim of "38% rule" but it is most certainly not a rule (not matter how much the misconception is continued to be pushed around).


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21214369
> 
> 
> Do you think he is close to over-treating his space? Every space I've been in with all plaster/plasterboard walls and a non-acoustical ceiling has been horrid, and what he's done has immensely improved the sound.
> 
> 
> If he wants to press on, then a calibrated mic and measuring software is needed. But maybe he's satisfied with the results and now just wants to enjoy it.



it was in response to one of his PM's - and id prefer to keep all of this in the public domain so others could gain from it.


you cant dictate "over-treating" without knowing what you want your end results to look like. you 'treat' as much as required to address a specific issue.


reiterating my previous comment - reflection points of specular energy are not tantamount to laser beams


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21215311
> 
> 
> it was in response to one of his PM's - and id prefer to keep all of this in the public domain so others could gain from it.
> 
> 
> you cant dictate "over-treating" without knowing what you want your end results to look like. you 'treat' as much as required to address a specific issue.
> 
> 
> reiterating my previous comment - reflection points of specular energy are not tantamount to laser beams



Yes, of course, on all of that. But me as a beginner, relative to you, and him as a beginner relative to me, I must toss out there that it is too easy to become overwhelmed by all the technical stuff at the beginning.


I think, so far, he has only improved his space's acoustics. Just like most similar spaces would be improved by what he has done. Now, if he wants to know more about his space and improve it further - if that is indicated by measuring, then he can do that. If that involves changing something he's already done, then so be it. But he _really likes_ the improvements, and that can either be an endpoint or a stepping off point to becoming more knowledgeable.


Jeff


----------



## FOH




> Quote:
> Originally Posted by *robc1976* /forum/post/21204935
> 
> 
> I just cant believe how much of a improvment accostics actually do



This is great.





> Quote:
> Originally Posted by *robc1976* /forum/post/21204935
> 
> 
> It seems like I hear detail in movies I actually never heard before?? The bass hits so sharp and there are bass notes I NEVER noticed before also.



Addition, ...by subtraction, nice.






> Quote:
> Originally Posted by *robc1976* /forum/post/21215029
> 
> 
> Yep, they where at the 50% mark and i moved them to the 38% mark and that improved bass a ton and got MLP from out from under the air duct.



Good job experimenting. It would be interesting to see the corresponding measurments.






> Quote:
> Originally Posted by *localhost127* /forum/post/21215303
> 
> 
> why 38%?
> 
> 
> there is a constant claim of "38% rule" but it is most certainly not a rule (not matter how much the misconception is continued to be pushed around).



Certainly not a mandate, every room is different, etc, adinfinitum,...however, I'd take a nice 38% point opposed to a 50% null filled/problematic point anytime.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21215303
> 
> 
> why 38%?
> 
> 
> there is a constant claim of "38% rule" but it is most certainly not a rule (not matter how much the misconception is continued to be pushed around).



I totally agree.....I basically had to either pic 50% (the farthest) or closer because of a staircase. I tried it at 50, 45,40, 38 and the 38 allowed me to do 2 things...had better bass and I my heights would come out of the corner abd be placed on the frontwalll since I want them at 45 degrees. My buddys system 38% didn't work so welll...he has his at 45% and it sounded the best.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21215276
> 
> 
> Pick some bottom-heavy content and listen with it before and after the Tri-trap installation. My favorite is the opening battle sequence in Master and Commander Far Side of the World.



You read my mind LOL!!! Also another one is war of the worlds where the alien craft comes out of the ground...OMG!!! That is pretty insane, I think they have VERY heavy LFE thru the entire movie!


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21215675
> 
> 
> Yes, of course, on all of that. But me as a beginner, relative to you, and him as a beginner relative to me, I must toss out there that it is too easy to become overwhelmed by all the technical stuff at the beginning.
> 
> 
> I think, so far, he has only improved his space's acoustics. Just like most similar spaces would be improved by what he has done. Now, if he wants to know more about his space and improve it further - if that is indicated by measuring, then he can do that. If that involves changing something he's already done, then so be it. But he _really likes_ the improvements, and that can either be an endpoint or a stepping off point to becoming more knowledgeable.
> 
> 
> Jeff



I have laerned a TON from BOTH of you and I thank you guys for that. I will admit I get overwelmed pretty easy...I actually learn best from almost seeing it...I am getting software also here soon. If I have to change something that is fine and would learn from it LOL!! I am concentrating on getting the foam out of the roon LOL!! I honestly just dont like it!!


----------



## pepar

M&C is my fav because of the cannonade of varying fundamentals and timbre. Not to mention timber cracking.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21215900
> 
> 
> M&C is my fav because of the cannonade of varying fundamentals and timbre. Not to mention timber cracking.



With 9 horns pointing at you it is intense!!! I have bought at least 60 bluerays this month LOL!!!


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/21215686
> 
> 
> Certainly not a mandate, every room is different, etc, adinfinitum,...however, I'd take a nice 38% point opposed to a 50% null filled/problematic point anytime.



that was not my objection. my objection is with people labeling it a "rule" that is unfortunately repeated by so many without even understanding that basis behind it - which will only further confuse the novice.


----------



## robc1976

Got the rest of the Tri-traps today, these made a HUGE difference!


----------



## pepar

Have you Mastered and Commandered them yet?


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21219140
> 
> 
> Have you Mastered and Commandered them yet?



Oh MY!!! LOL!!! I used to listen to my system at -10 and sometimes even -8 and there is NO way I could do it now







......my ears would bleed!I guess this is a good thing??? does this mean that the sound is better because it is a LOT louder (granted Audyssey set the trims a tad higher). The sound is a lot more detailed but it is a LOT louder. This may sound crazy but could that be a high frequency wave? My ears where ringing LOL!! One thing is I havent treated the back wall yet (well I have cheap Auralex 1.5" diffusor...pretty much a joke!). This could be a reflection off the back wall...I am NOT saying it doesn't sound good it is just intense. The bass is unreal......I feel it in my chest...not just the low bass but even subtle sounds that have bass I never new did I hear now...pretty awesome!


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *robc1976* /forum/post/21219254
> 
> 
> I used to listen to my system at -10 and sometimes even -8 and there is NO way I could do it now
> 
> 
> 
> 
> 
> 
> 
> ......my ears would bleed!I guess this is a good thing??? does this mean that the sound is better because it is a LOT louder (granted Audyssey set the trims a tad higher).



Hmm, odd, treatments usually have the opposite effect - you can listen louder because you've tamed some of the ringing / excess reverberation. Have you recalibrated using Audyssey / MCACC / YPAO / whatever, to reset your reference level?


----------



## pepar




> Quote:
> Originally Posted by *robc1976* /forum/post/21219254
> 
> 
> Oh MY!!! LOL!!! I used to listen to my system at -10 and sometimes even -8 and there is NO way I could do it now
> 
> 
> 
> 
> 
> 
> 
> ......my ears would bleed!I guess this is a good thing??? does this mean that the sound is better because it is a LOT louder (granted Audyssey set the trims a tad higher). The sound is a lot more detailed but it is a LOT louder. This may sound crazy but could that be a high frequency wave? My ears where ringing LOL!! One thing is I havent treated the back wall yet (well I have cheap Auralex 1.5" diffusor...pretty much a joke!). This could be a reflection off the back wall...I am NOT saying it doesn't sound good it is just intense. The bass is unreal......I feel it in my chest...not just the low bass but even subtle sounds that have bass I never new did I hear now...pretty awesome!



The diffusors back there are doing something. And it's ten feet away, isn't it?


I'm inclined to agree with Brad ... that things are cleaned up and sounds are now more distinct.


----------



## robc1976




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21219454
> 
> 
> Hmm, odd, treatments usually have the opposite effect - you can listen louder because you've tamed some of the ringing / excess reverberation. Have you recalibrated using Audyssey / MCACC / YPAO / whatever, to reset your reference level?



I did recalibrate with X32...I might recalibrate again...it is some kinda of tone...almost like a ringing....HMMM?? I think it is from possibly the back wall.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21219622
> 
> 
> The diffusors back there are doing something. And it's ten feet away, isn't it?
> 
> 
> I'm inclined to agree with Brad ... that things are cleaned up and sounds are now more distinct.



The diffusors are now about 13+ feet away.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21219622
> 
> 
> I'm inclined to agree with Brad ... that things are cleaned up and sounds are now more distinct.



There are sounds I have NEVER heard in tracks...I mean little sounds to...like dogs barking in the backround ECT...pretty awesome.


----------



## pepar

It must have been a cacophonous mess before.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21219670
> 
> 
> It must have been a cacophonous mess before.



It was!!!! LOL!! No bass...no detail...just a fuzzy mess!


----------



## FOH




> Quote:
> Originally Posted by *robc1976* /forum/post/21219254
> 
> 
> The bass is unreal......I feel it in my chest...not just the low bass but even subtle sounds that have bass I never new did I hear now...pretty awesome!



I fully understand this is a subjective statement, and who knows exactly what's happening, however you gotta love anecdotal findings such as those.


The proper/added delineation of bass detail was the biggest difference I felt accompanied my initial foray into acoustic treatment. Cleaning up the time domain aspects, me likey.



Good luck


----------



## robc1976




> Quote:
> Originally Posted by *FOH* /forum/post/21219925
> 
> 
> I fully understand this is a subjective statement, and who knows exactly what's happening, however you gotta love anecdotal findings such as those.
> 
> 
> The proper/added delineation of bass detail was the biggest difference I felt accompanied my initial foray into acoustic treatment. Cleaning up the time domain aspects, me likey.
> 
> 
> 
> Good luck



I agree...when you here like a metal door close and the subtle bass you never heard before...makes you smile LOL!!


I think the raeson my ears hurt is because of a sinus infection...my wife listen and said "that is awesome" lets get more treatments for the back wall!!" Man am I lucky!!


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *robc1976* /forum/post/21220093
> 
> 
> my wife listen and said "that is awesome" lets get more treatments for the back wall!!" Man am I lucky!!



Man that's nice - I'm at least happy that my wife seems to be accilimating to the volume level I use, and doesn't say "its so loud" as much anymore.


----------



## myfipie




> Quote:
> Originally Posted by robc1976 View Post
> 
> I just cant believe how much of a improvment accostics actually do



wow looks like the room is really coming together. Please email me some pictures when you get a moment. Always like to pass them around the office from happy customers!!


Glenn


----------



## robc1976




> Quote:
> Originally Posted by *myfipie* /forum/post/21220797
> 
> 
> wow looks like the room is really coming together. Please email me some pictures when you get a moment. Always like to pass them around the office from happy customers!!
> 
> 
> Glenn



Hey Glenn!! I am a VERY happy customer...You have the best customer service from any company I have ever delt with...pretty awesome!!


I am deciding what to do on the back wall also...just emailed Bpape to LOL!! I will get ya some pics in a few!


----------



## pepar




> Quote:
> Originally Posted by *myfipie* /forum/post/21220797
> 
> 
> wow looks like the room is really coming together. Please email me some pictures when you get a moment. Always like to pass them around the office from happy customers!!
> 
> 
> Glenn



Glenn,


What, if any, recommendations did GIK make to him?


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21221420
> 
> 
> Glenn,
> 
> 
> What, if any, recommendations did GIK make to him?
> 
> 
> Jeff



I have gottren a Ton of suggestions from you and locost...have I filled up your PM box yet LOL!!










Gik suggested to make the front wall completelly filled with absorbtion, they suggested the tri-traps (love those) and panels on the side walls as welll like you also suggested. They suggest to adress the front wall before the back wall but I am not sure I am going with the completely dead front wall yet or not.


----------



## robc1976

Well I recalibrated and it sounds MUCH better..I think the mic was below seat level and had some sort of reflection and set the trims way to high, Also thanks Pepar for the mic position trick...got a great sub distance measurement.


----------



## myfipie




> Quote:
> Originally Posted by *robc1976* /forum/post/21220814
> 
> 
> Hey Glenn!! I am a VERY happy customer...You have the best customer service from any company I have ever delt with...pretty awesome!!
> 
> 
> I am deciding what to do on the back wall also...just emailed Bpape to LOL!! I will get ya some pics in a few!



Thanks for noting about our customer service. We, as in every member of GIK Acoustics take a lot of pride in having the best customer service we can. Seems to be a lost "thing" in our day to day lives.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/21221420
> 
> 
> Glenn,
> 
> 
> What, if any, recommendations did GIK make to him?
> 
> 
> Jeff



Let me see if I can get Bryan to chime in here. He was the one working with him with his room.


----------



## NicksHitachi




> Quote:
> Originally Posted by *robc1976* /forum/post/0
> 
> 
> Well I recalibrated and it sounds MUCH better..I think the mic was below seat level and had some sort of reflection and set the trims way to high, Also thanks Pepar for the mic position trick...got a great sub distance measurement.



What mic position trick?


----------



## bpape

We basically got rid of the foam that was sucking up all the high frequencies and leaving everything else pretty much untouched. Added some broadband bass control in the front corners and replaced the side and ceiling reflection points with 242's which go a lot lower.


I have also recommended deadening the entire front wall to address reflections from the surround channels.


I also recommended a bit less toe in on the channels since the horns on axis can get pretty intense. We also moved his height channels out of the corners and over a bit so we could trap them and help with the corner gain they were getting that was changing relative tonal balance.


Now we're working on what to do in the rear 1/2 of the room. Likely a mix of some additional bass control and some diffusion for the surround field.


Bryan


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/21223559
> 
> 
> We basically got rid of the foam that was sucking up all the high frequencies and leaving everything else pretty much untouched. Added some broadband bass control in the front corners and replaced the side and ceiling reflection points with 242's which go a lot lower.
> 
> 
> I have also recommended deadening the entire front wall to address reflections from the surround channels.
> 
> 
> I also recommended a bit less toe in on the channels since the horns on axis can get pretty intense. We also moved his height channels out of the corners and over a bit so we could trap them and help with the corner gain they were getting that was changing relative tonal balance.
> 
> 
> Now we're working on what to do in the rear 1/2 of the room. Likely a mix of some additional bass control and some diffusion for the surround field.
> 
> 
> Bryan



As I understand his situation, measuring did not play a roll in your recommendations. At what point would measurements be needed to treat beyond your initial recommendations?


My context is the always-measure-first proponents vs. my thinking that a beginner with a space such as his can deploy "the basics" and be completely confident that there will be dramatic improvements with no danger of doing harm.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21223442
> 
> 
> What mic position trick?



Shift the first Audyssey measurement position by an inch or two to see if the detected sub distance aligns better with the physical distance.


----------



## bpape

We did not take a measurement initially. He already had the space treated and was looking to broaden the effects that he already had using the foam. Now we're into the stage of adding additional items to finish it off.


I have spoken to him about the overall plan after the front is done to make an assessment at that point as to how we want to proceed in the rear in terms of balancing the bass control overall in the room.


I did make a recommendation to do 2 subs - 1 front and 1 rear and see what we could do with any response issues.


Bryan


----------



## nickbuol

I almost hate to ask the question since things have been fairly focused on someone else's room for a while, but I was at a hardware store today picking up some items for my whole basement finish (which includes a home theater) and I saw that they had some 3.5" thick R13 and 5" (or was it 5.5") thick R19 material made out of 80% recycled denim (cotton). I am planning on front super chunk bass traps already, and after some recent reading, think that I want to cover the whole front wall with something as well. It will be behind a false front wall with a Seymour AT screen, so it doesn't need to look pretty, although I would frame and cover it for stability.


Anyway, would the 3.5" R13 denim work to cover the front wall? I do NOT plan to use something like that for the super chunks. I am looking at an AVS vendor's 703/705 alternatives for the bass traps.


Just looking for an inexpensive option for the front wall since it doesn't need to look pretty.

Also, this is just a part of a whole room treatment, but oddly it is the last piece that I am considering adding.


I couldn't find any density rating on the packaging...


----------



## pepar




> Quote:
> Originally Posted by *bpape* /forum/post/21224209
> 
> 
> I did make a recommendation to do 2 subs - 1 front and 1 rear and see what we could do with any response issues.
> 
> 
> Bryan



That, too, seems like a "basic" that will always help and never harm.


Jeff


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21223977
> 
> 
> Shift the first Audyssey measurement position by an inch or two to see if the detected sub distance aligns better with the physical distance.



And it worked perfectly....Even helped with my other speakers also!!


----------



## robc1976




> Quote:
> Originally Posted by *bpape* /forum/post/21224209
> 
> 
> We did not take a measurement initially. He already had the space treated and was looking to broaden the effects that he already had using the foam. Now we're into the stage of adding additional items to finish it off.
> 
> 
> I have spoken to him about the overall plan after the front is done to make an assessment at that point as to how we want to proceed in the rear in terms of balancing the bass control overall in the room.
> 
> 
> I did make a recommendation to do 2 subs - 1 front and 1 rear and see what we could do with any response issues.
> 
> 
> Bryan



I will be getting another sub to and will do that....I am going to need about a 40 ft sub cable LOL!!!


----------



## pepar

Get a sub identical to your present one.


----------



## robc1976




> Quote:
> Originally Posted by *pepar* /forum/post/21225047
> 
> 
> Get a sub identical to your present one.



I was planning on it.....that will be a lot of bass LOL!! actually more headroom I am assumming and a more even response with less nulls?


----------



## pepar

Yes, not really more bass as the system will still be operating at the same SPL as before, but you will have smoother bass because room modes will be lessened. And you should experience what is best described as more effortless bass.


Jeff


----------



## nickbuol




> Quote:
> Originally Posted by *nickbuol* /forum/post/21224949
> 
> 
> I almost hate to ask the question since things have been fairly focused on someone else's room for a while, but I was at a hardware store today picking up some items for my whole basement finish (which includes a home theater) and I saw that they had some 3.5" thick R13 and 5" (or was it 5.5") thick R19 material made out of 80% recycled denim (cotton). I am planning on front super chunk bass traps already, and after some recent reading, think that I want to cover the whole front wall with something as well. It will be behind a false front wall with a Seymour AT screen, so it doesn't need to look pretty, although I would frame and cover it for stability.
> 
> 
> Anyway, would the 3.5" R13 denim work to cover the front wall? I do NOT plan to use something like that for the super chunks. I am looking at an AVS vendor's 703/705 alternatives for the bass traps.
> 
> 
> Just looking for an inexpensive option for the front wall since it doesn't need to look pretty.
> 
> Also, this is just a part of a whole room treatment, but oddly it is the last piece that I am considering adding.
> 
> 
> I couldn't find any density rating on the packaging...



I'm thinking that my question got overlooked.







It has only been about 9 hours, but I could see it getting lost in the mix...


----------



## myfipie




> Quote:
> Anyway, would the 3.5" R13 denim work to cover the front wall? I do NOT plan to use something like that for the super chunks. I am looking at an AVS vendor's 703/705 alternatives for the bass traps.



Personally at that density I would go with the 5" or thicker. The 3.5" will help but may not reach into the low end like you want.


----------



## nickbuol

OK. The price wasn't much different between the two products. Do you think something rated at "R19" at 5" will help, or does it need to show some specific density rating. R19 is the insulation rating, but heck, you could fill a space with 2 feet of a non-dense material and get a decent R value with little acoustical benefit.


Basically, I don't want to put up something that is not going to help at all.


----------



## localhost127




> Quote:
> Originally Posted by *nickbuol* /forum/post/21227990
> 
> 
> OK. The price wasn't much different between the two products. Do you think something rated at "R19" at 5" will help, or does it need to show some specific density rating. R19 is the insulation rating, but heck, you could fill a space with 2 feet of a non-dense material and get a decent R value with little acoustical benefit.
> 
> 
> Basically, I don't want to put up something that is not going to help at all.



pink fluffy (low flow-resistivity) material makes for excellent porous (velocity-based) bass traps.


----------



## nickbuol

Back to the pink fluffy discussion... I am still not 100% sold on that. Maybe it works, but it hasn't been as common or tried and tested nearly as much as other products. I'm not sure that I want to be in the testing group for it, although if it is as good, then it is a great cost savings.


----------



## pepar

I think it takes a lot of it ... a lot of physical space.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21229229
> 
> 
> I think it takes a lot of it ... a lot of physical space.



34" faced super chunks.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21229303
> 
> 
> 34" faced super chunks.



Of pink fluffy? Same performance as 3pcf 'glass?


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21229399
> 
> 
> Of pink fluffy? Same performance as 3pcf 'glass?



~5000 rayls/m flow-resistivity pink fluffy insulation - loosely filled (eg, NOT compressed).


----------



## pepar

I am certain that that means something to you and a few others on this thread.










Jeff


----------



## myfipie




> Quote:
> Originally Posted by *nickbuol* /forum/post/21227990
> 
> 
> OK. The price wasn't much different between the two products. Do you think something rated at "R19" at 5" will help, or does it need to show some specific density rating. R19 is the insulation rating, but heck, you could fill a space with 2 feet of a non-dense material and get a decent R value with little acoustical benefit.
> 
> 
> Basically, I don't want to put up something that is not going to help at all.



I can't find the link right now but if you search on the realtraps site Ethan did a test with less dense and more dense fiberglass. In the end, for thinner panels more dense worked better but as it got thicker the less dense did just fine. If you want to play it safe I would put 2 layers to make 10". Honestly though I have not used that product, nor tested it so YMMV on it. Also understand that when Ethan tested this he was straddling corners and there are other factors like "string" action going on with more density fiberglass straddling corners.

Confused now??????????














Welcome to DIY land.


----------



## nickbuol

Corner bass traps will be traditional (tried and true) stuff like 703/705 or a known equivalent. I'm just looking for something to put on the flat part of the wall between the corner bass traps...


Sort of like what Sandman did in his masterful build....


I stole this from page 75 of his Build Thread... 


Ignore the speakers, I am talking about the wall treatment...


----------



## localhost127




> Quote:
> Originally Posted by *myfipie* /forum/post/21229746
> 
> 
> I can't find the link right now but if you search on the realtraps site Ethan did a test with less dense and more dense fiberglass. In the end, for thinner panels more dense worked better but as it got thicker the less dense did just fine. If you want to play it safe I would put 2 layers to make 10". Honestly though I have not used that product, nor tested it so YMMV on it. Also understand that when Ethan tested this he was straddling corners and there are other factors like "string" action going on with more density fiberglass straddling corners.
> 
> Confused now??????????
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Welcome to DIY land.



yes, but he wasn't testing very thick traps either (just straddled panels --- not even 34" faced):
http://www.ethanwiner.com/density.html


----------



## dragonleepenn




> Quote:
> Originally Posted by *nickbuol* /forum/post/21227009
> 
> 
> I'm thinking that my question got overlooked.
> 
> 
> 
> 
> 
> 
> 
> It has only been about 9 hours, but I could see it getting lost in the mix...



My front wall and f/corners are designed with this product. It's called ultra-touch denim insulation, do a google search for more info. I love it, i have a false wall studded for 24" on center, the ultra touch comes in 16" or 24" wide by 3.5/5.5/thick and 94" high. I say cover the entire front wall and make some bass traps with this material. I made some 24" by 72" corner traps at the rear. I used this matrial for six clouds at the front of the room, these traps are of different sizes. I did super chunks at the front corners and like the results. Think of using roxul, i made some 2x4 traps and love the way they are working out for me. I've made some diffusers from wood for the rear and ceiling saving some money in the process. There are many products that work! Get greative.


----------



## localhost127




> Quote:
> Originally Posted by *localhost127* /forum/post/21230051
> 
> 
> yes, but he wasn't testing very thick traps either (just straddled panels --- not even 34" faced):
> http://www.ethanwiner.com/density.html



and adding on to that, it wasn't a very intrusive test regarding thickness - the overall test (due to static number of fibre batts) was more along the lines of _"more, thinner panels"_ vs _"less, thicker panels"_ ... eg, if one was constricted to a low number of panels, what is the best way to deploy?


...but still, the results show unresolved LF modal issues in the frequency response and time-domain (hence, thicker panels are still required - along with adequate coverage).


----------



## nickbuol




> Quote:
> Originally Posted by *dragonleepenn* /forum/post/21231199
> 
> 
> My front wall and f/corners are designed with this product. It's called ultra-touch denim insulation, do a google search for more info. I love it, i have a false wall studded for 24" on center, the ultra touch comes in 16" or 24" wide by 3.5/5.5/thick and 94" high. I say cover the entire front wall and make some bass traps with this material. I made some 24" by 72" corner traps at the rear. I used this matrial for six clouds at the front of the room, these traps are of different sizes. I did super chunks at the front corners and like the results. Think of using roxul, i made some 2x4 traps and love the way they are working out for me. I've made some diffusers from wood for the rear and ceiling saving some money in the process. There are many products that work! Get greative.



Yea, that is the exact stuff. I saw it at my local Menards store...


Did you go with the R13 or R19 stuff?


----------



## dragonleepenn




> Quote:
> Originally Posted by *nickbuol* /forum/post/21231249
> 
> 
> Yea, that is the exact stuff. I saw it at my local Menards store...
> 
> 
> Did you go with the R13 or R19 stuff?



I went with the R13, it also comes in a R19 R21 and R30. The R30 is eight inches thick.


----------



## orcarola25

Would the 3.5" ultratouch denim be a good material for treating first reflections as well. It seems to have balanced absorption characteristics down to 125hz.


----------



## dragonleepenn




> Quote:
> Originally Posted by *orcarola25* /forum/post/21231868
> 
> 
> Would the 3.5" ultratouch denim be a good material for treating first reflections as well. It seems to have balanced absorption characteristics down to 125hz.



It works just fine as a first reflection treatment for me. I'm suprised more people here are'nt using it, you'll fine that there is another company that sells a similar product,actually its the same denim material just different name and brand that sells it as a acoustical treatment. All the specs are the same.


----------



## FOH

What's a good source for the demin or acoustic cotton material?


----------



## RUR




> Quote:
> Originally Posted by *FOH* /forum/post/21232215
> 
> 
> What's a good source for the demin or acoustic cotton material?


 http://www.bondedlogic.com/distributor-locator 


Pretty ubiquitous, actually.


----------



## orcarola25




> Quote:
> Originally Posted by *dragonleepenn* /forum/post/0
> 
> 
> 
> It works just fine as a first reflection treatment for me. I'm suprised more people here are'nt using it, you'll fine that there is another company that sells a similar product,actually its the same denim material just different name and brand that sells it as a acoustical treatment. All the specs are the same.



Any ideas what the name is of the secondary company is that sells the ultratouch equivalent. Wonder if they sell it cheaper. Add acoustic to name of these materials and all of a sudden they are priced as gold!!!


I am kind of surprised of its limited use or recommendation around the forum. It is cotton for starters not half as nasty to work with. It is the thickness of a stud which can make it more flexible as a treatment in new theater construction.


Locally for me, it seems to be similar in price as OC. I guess it comes down to availability in your area.


----------



## dragonleepenn




> Quote:
> Originally Posted by *orcarola25* /forum/post/21232482
> 
> 
> Any ideas what the name is of the secondary company is that sells the ultratouch equivalent. Wonder if they sell it cheaper. Add acoustic to name of these materials and all of a sudden they are priced as gold!!!
> 
> 
> I am kind of surprised of its limited use or recommendation around the forum. It is cotton for starters not half as nasty to work with. It is the thickness of a stud which can make it more flexible as a treatment in new theater construction.
> 
> 
> Locally for me, it seems to be similar in price as OC. I guess it comes down to availability in your area.



This company has both products/one is sold as insulation the other is an acoustical material specific for such. Check out the sizes on both you can see the amount of product you get for each relative to purpose. You can check out the specs on both and compare. I selected wisely, the one sold as insulation, ultra touch. http://www.soundaway.com


----------



## Bullitt5094

Any way I can good some good basic Acoustic Treatment ideas for a dedicated Media Room without reading the 9+ years of posts in this tread? I'm not lazy, but I would like to finish my research before the house and room is finished in three months!


----------



## Elill




> Quote:
> Originally Posted by *Bullitt5094* /forum/post/21258858
> 
> 
> Any way I can good some good basic Acoustic Treatment ideas for a dedicated Media Room without reading the 9+ years of posts in this tread? I'm not lazy, but I would like to finish my research before the house and room is finished in three months!



Dont waste your time reading the thread - too much conflicting views.


I'd suggest Floyd Toole's book,, Sound Reproduction OR

http://www.avsforum.com/avs-vb/showthread.php?t=1267433


----------



## atabea

Hi all, I am in the process of re-disigning my HT room/basement. In the last couple of days, I decided to go with an AT screen and build a false wall with all three speakers going behind the screen. Althouhg I have read till my eyes hurt, I thought I should ask the following questions for absolute clarification:


1) From what I understand, in the case of a false wall/AT screen, the front wall MUST be acoustically treated. This is where I am uncertain: There are two different types of scoustic treatment available (a) the rigid insulation board from Johns Manville known as the JOHNS MANVILLE LINACOUSTIC Rigid Fiber Glass Plenum Liner Board and (b) the Linacoustic RC

Fiber Glass Duct Liner With Reinforced Coating System. Which is the right one to use?


2) Regardless of which one I end up using, is it correct to install the Linacoustic from floor to ceiling on the front wall (behind the false wall)?


3) Do I have to install the same Linacoustic on the side walls up to ear level only? Should I install floor to ceiling as on the front wall?


4) Should I move my subwoofer to behind the false wall (in one of the corners and next to the front speakers? I previously had it right next to the seating position.


Thanks,


atabea


----------



## myfipie




> Quote:
> Originally Posted by *Bullitt5094* /forum/post/21258858
> 
> 
> Any way I can good some good basic Acoustic Treatment ideas for a dedicated Media Room without reading the 9+ years of posts in this tread? I'm not lazy, but I would like to finish my research before the house and room is finished in three months!



It is a lot to take in!! Here are a few articles we have done that might bring you up to speed.
http://www.gikacoustics.com/education.html 
http://www.gikacoustics.com/news_081610.html 


The following is a video (sorry English subtitles) of a room with and without treatment. It not only tests the room but also records music with and without treatment so you can hear the difference.

Hope that helps

http://www.gikacoustics.com/treated_video.html


----------



## atabea

Anybody?? I am really looking forward to getting this process completed and if the advice is to go ahead with acoustic insulation, then I want to start with that. I just need to know what is the right approach.


Thanks


atabea


[atabea;21260712]Hi all, I am in the process of re-disigning my HT room/basement. In the last couple of days, I decided to go with an AT screen and build a false wall with all three speakers going behind the screen. Althouhg I have read till my eyes hurt, I thought I should ask the following questions for absolute clarification:


1) From what I understand, in the case of a false wall/AT screen, the front wall MUST be acoustically treated. This is where I am uncertain: There are two different types of scoustic treatment available (a) the rigid insulation board from Johns Manville known as the JOHNS MANVILLE LINACOUSTIC Rigid Fiber Glass Plenum Liner Board and (b) the Linacoustic RC

Fiber Glass Duct Liner With Reinforced Coating System. Which is the right one to use?


2) Regardless of which one I end up using, is it correct to install the Linacoustic from floor to ceiling on the front wall (behind the false wall)?


3) Do I have to install the same Linacoustic on the side walls up to ear level only? Should I install floor to ceiling as on the front wall?


4) Should I move my subwoofer to behind the false wall (in one of the corners and next to the front speakers? I previously had it right next to the seating position.


Thanks,


atabea[/quote]


----------



## Brad Horstkotte

1) If you mean between these two (below), I'd take the second, based on better acoustic absorption numbers, which are listed towards the bottom of the two spec sheets (but I've seen a lot of builds use the first, really either will work):

http://www.specjm.com/files/pdf/AHS-329.pdf 
http://www.specjm.com/files/pdf/AHS-156.pdf 


2) Yes, I'd do floor to ceiling on the front wall.


3) There it starts getting tricky - that method seems to have fallen out of favor recently, and absorption / diffusion of just specific areas, based on acoustic measurements, is preferred. Many use the mirror method to determine locations, but a better approach is to measure first - since depending on the room and speakers, you might not need anything.


4) There is no answer that will suit all rooms, you'll need to experiment with different locations if the best audio performance is your #1 goal. On the other hand, if you're like most people with a false wall, aesthetics is part of the equation. I put my subs behind the screen, because they're too darn big for me to be happy with them anywhere else, I want that clean look. Better from an acoustics perspective would probably have been midpoint of non-opposing walls. But with a healthy dose of EQ, I've made it work well.


----------



## atabea

Thank you so much Brad! I now have a place to start--I will line the front wall with the Linacoustic roll and place the sub behind the wall ( I too like some aesthetics). I am not sure what the "mirror" method means or even how to "measure." I suppose I could just line the side walls and see how that sounds and if I don't like the sound I could always remove it.


Thanks again.


atabea




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21272219
> 
> 
> 1) If you mean between these two (below), I'd take the second, based on better acoustic absorption numbers, which are listed towards the bottom of the two spec sheets (but I've seen a lot of builds use the first, really either will work):
> 
> http://www.specjm.com/files/pdf/AHS-329.pdf
> http://www.specjm.com/files/pdf/AHS-156.pdf
> 
> 
> 2) Yes, I'd do floor to ceiling on the front wall.
> 
> 
> 3) There it starts getting tricky - that method seems to have fallen out of favor recently, and absorption / diffusion of just specific areas, based on acoustic measurements, is preferred. Many use the mirror method to determine locations, but a better approach is to measure first - since depending on the room and speakers, you might not need anything.
> 
> 
> 4) There is no answer that will suit all rooms, you'll need to experiment with different locations if the best audio performance is your #1 goal. On the other hand, if you're like most people with a false wall, aesthetics is part of the equation. I put my subs behind the screen, because they're too darn big for me to be happy with them anywhere else, I want that clean look. Better from an acoustics perspective would probably have been midpoint of non-opposing walls. But with a healthy dose of EQ, I've made it work well.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *atabea* /forum/post/21272300
> 
> 
> I am not sure what the "mirror" method means or even how to "measure."



Here's a description of the "mirror trick", which is used to locate approximate locations of "first reflection points" - the locations on the walls where sound will bounce off, on its way from each of the speakers to each of the listening positions (seats). Those reflections are one of the main things being addressed by the addition of absorption.

http://www.auralex.com/auralex_acous...mirrortest.asp 


Measurement (ETC measurement mentioned in that definition above) means measure using a microphone attached to a PC, using acoustic analysis software such as REW (Room EQ Wizard - free). It can tell you (a) do you have a problem that needs treatment; and (b) after treatment, have you addressed that problem.


----------



## localhost127

atabea,

please take a moment to read this thread:
http://www.avsforum.com/avs-vb/showthread.php?t=1372192 


it's a long one - but it is important to understand that if one is utilizing absorption to attenuate early, high-gain specular reflections (as you are doing at the sidewall reflection points and elsewhere), it is vital to use a sufficient broadband absorber to fully attenuate the specular reflection ... vs using thin absorption to simply filter or EQ the band of which has the least energy content to begin with....


measurements are generally required to verify an existing problem as well as for confirmation once the absorber has been placed ... and this can be done with the ETC response as part of the free software measuring suite: Room EQ Wizard.


you'll notice that some of the theater experts here may recommend 'diffusion', or may say that their choice of absorption/diffusion/hybrid depends on the polar axis of the speaker - but i have yet to see anyone elaborate as to how such decisions are made or what types of 'polar responses' of the speakers dictate their choices.


there is also the issue of diffusers being effective only in the mid or HF band of the specular region, which is essentially the same effect as applying thin absorption which does not address the full specular reflection with attention to the lower band where the bulk of the energy content is and the wavelengths are longest.


specular energy is energy that can be modeled like light - hence the mirror trick described by Brad above is a crude way of determining what large surfaces or boundaries may have energy incident from the speaker. eg, if you sit in your listening position and have a friend hold up a mirror on the sidewall, and move it until you can see a speaker's acoustic center in the mirror, then that is a geometric reflection point that may be a candidate for absorption. you look for the acoustic center of the speaker, NOT the tweeter, as the acoustic center has the bulk of the energy content of which the absorber must be sufficient to attenuate. the tweeter contains the wavelengths with the least energy content, so they are not as difficult to attenuate.


of course, the mirror only gives you crude approximations on large boundaries. it does not provide you with detail of the time arrival of the specular energy, its gain (with respect to the original signal), nor the performance of the absorber once it has been placed to verify the proper attenuation of the specular reflection. it's a crude tool but it can help the novice understand how specular energy behaves within a small acoustical space. just understand the limitations.


----------



## Dennis Erskine

There are two inch products that will get down to the Schroder frequency. (For example -- Class A --- 125Hz - .73, 250Hz - .95, 500Hz - 1.17, 1000Hz - 1.16, 4000Hz - 1.13) and 2" products that won't eat your HF (for example [email protected] and [email protected]). However, the underlying, oft ignored component in all of this is the failure to recognize you have a wall behind these treatments and the wall itself contributes to the room acoustics (it has an impedance, it has absorption characteristics) and you really don't have just a piece of something, you in fact have a composite, and that composite behaves as a different material...not the sum of all the materials. So, if you get "whacked" by a CDO (OCD in alphabetical order), well don't get cornfused with big words.


Path differences (hence phase differences) and absorption by frequency in air over distance is easily calculated. Where both absorption and diffusion is called for "PerfSorberLR.pdf" illustrates a product in that domain.


If you look at "good off axis", as you measure off axis, a well behaved speaker will resemble this plot. Note as the frequencies roll off as you move off axis, the plot has the same shape. This would likely call for diffusion. If you look at "bad off axis", you'll see the behavior of a less than well behaved speaker. This speaker would call for absorption ... you really don't want the poor frequency response (off axis) of this speaker redirected, reflected or otherwise injected into the listening positions of the room.
 
 

 

PerfSorberLR.pdf 237.13671875k . file


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21274413
> 
> 
> There are two inch products that will get down to the Schroder frequency. (For example -- Class A --- 125Hz - .73, 250Hz - .95, 500Hz - 1.17, 1000Hz - 1.16, 4000Hz - 1.13) and 2" products that won't eat your HF (for example [email protected] and [email protected]).





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21274413
> 
> 
> attached file:





> Quote:
> *ISO 17497-1:2004*
> 
> Acoustics -- Sound-scattering properties of surfaces -- Part 1: Measurement of the *random-incidence* scattering coefficient in a *reverberation room*



yes, and when interpreting such values, one needs to understand that random incidence (reverberant/diffuse-field) does not exist in a small acoustical place - and one needs to be accounting for angle of incidence.



> Quote:
> "The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. Normal incidence absorption coefficients are percentages. The two are often confused in the literature. A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material."


----------



## myfipie




> Quote:
> "The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. Normal incidence absorption coefficients are percentages. The two are often confused in the literature. A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material."



Better way to say it "Look at the sabins per unit".


----------



## atabea

Wow! the terminology and language in general is so far beyond me that I think I need a physics/electronics class or something to even begin to understand what you guys are saying.


atabea


----------



## fotto




> Quote:
> Originally Posted by *atabea* /forum/post/21275579
> 
> 
> Wow! the terminology and language in general is so far beyond me that I think I need a physics/electronics class or something to even begin to understand what you guys are saying.
> 
> 
> atabea



LOL. You didn't think you could just "splash around in the puddle" now did you?









Gonna have to get wet on this topic....soppy drenching wet I say!


----------



## Dennis Erskine




> Quote:
> yes, and when interpreting such values, one needs to understand that random incidence (reverberant/diffuse-field) does not exist in a small acoustical place - and one needs to be accounting for angle of incidence.



Yeah. So. You think I need to know that?


A reverberant field does exist in a small room ... just not a fully random homogeneous one. Any suggestion that an item tested under standard lab conditions is not appropriate, or won't work in a small room is just arm waving.



> Quote:
> Wow! the terminology and language in general is so far beyond me that I think I need a physics/electronics class or something to even begin to understand what you guys are saying.



Hah! Think that's a new language...sit on an ISO or (particularly) an ITU working party...now there's a whole new lexicon and set of rules.


If you'll note, Atabea, as is typical, the response didn't add anything to the conversation; but, was strictly an effort to be overly critical (and perhaps to impress people). The language changes after you put down the slide rule, get out of the office, and actually build (and measure) a hundred or so rooms. The language usually becomes monosyllable and much better understood by all.










So, to cut through the krap ... most enthusiats do not have the predictive tools (or need) to model coefficients vs percentage, non-incident vs random incident (basic geometry). This is supposed to be fun?! The basic point is just slapping a piece of fiberglass on early reflection points may not be the best approach. If you don't care to invest several months of time, don't have the budget (or desire) to purchase acoustic measurement equipment or hire a "professional", there are a few things you can do. One is to buy a couple of absorption panels and perhaps a couple of hybrid panels (like and absorber/diffuser) and place them on the side walls between your seating location and the speakers ... move them, swap them out, until it begins to sound better (one key metric is the dialog is understandable, another is you don't have to keep adjusting the volume between loud scenes and quiet scenes...and then continue the process until you're happy with your room. Splitting hairs is never productive when the low hanging fruit is the first priority.


If you want to take it further than that, you can read Floyd Toole's book "Sound Reproduction", you can take an HAA ( www.homeacoustics.net ) class, or you can go all in and spend several months collecting approaches, opinions, reading, and gaining an understanding of what "stuff" does to sound in a small room. Or, you can spend the bucks and hire Floyd!


I think you got a pretty reasonable answer about mirror points. Yup, there are a lot of them but keep the low hanging fruit in mind, address the big stuff first, and over time nail the nits.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21276458
> 
> 
> Yeah. So. You think I need to know that?



sure. far too often are such coefficient values presented on this forum without anyone taking the time to explain or understand how they were obtained and how they may or may not be relevant to the rooms most of us here are constrained to.


it should also be pointed out you provided data to a complete novice, of which no explanation of what those values meant. far too often we have people assuming those values are 'percentages' - and may make the misunderstanding. the statement was made to address any possible misconceptions the user or any other passive reader may have regarding such test facilities and standards. i'd love to hear you try and spin how you feel this is somehow "not relevant" considering this is the "acoustical treatment master thread"...




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21276458
> 
> 
> A reverberant field does exist in a small room ... *just not a fully random homogeneous one.*












that is a contradictory statement. how can it be a reverberant field if the energy flow is not equal/homogeneous in all directions? there is no reverberant soundfield for the frequencies relevant to small acoustical spaces - and what little exists in the higher frequencies in itself is lower than the noise floor.




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21276458
> 
> 
> Any suggestion that an item tested under standard lab conditions is not appropriate, or won't work in a small room is just arm waving.



it's not that it isn't appropriate - just that one needs to understand how such values may or may not be directly relevant to how the unit performs in their room. i find it slightly odd you consider such commentary as 'arm waving' ... it's quite applicable knowledge - especially when we have so many people on this subforum quoting Bob Gold's absorption coefficient page without somuch as reading the 2nd paragraph.


specular reflections dominate small acoustical spaces, and sidewall treatment properties can change dramatically with angle of incidence.




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21276458
> 
> 
> If you'll note, Atabea, as is typical, the response didn't add anything to the conversation; but, was strictly an effort to be overly critical (and perhaps to impress people). The language changes after you put down the slide rule, get out of the office, and actually build (and measure) a hundred or so rooms. The language usually becomes monosyllable and much better understood by all.



if i wanted to impress people, id mimic your signature.


im here to discuss and learn acoustics, not market a company and sell rooms, room designs, products, etc.


back to the product, is there a particular reason why the scattering coefficient was used and diffusion coefficient was omitted/not tested in the perf-sorber product data sheet?


----------



## nickbuol

This ought to be interesting. Mr. Pink Fluffy vs. Dennis (someone considered to be an expert in the field)....


----------



## Elill




> Quote:
> Originally Posted by *localhost127* /forum/post/21278161
> 
> 
> if i wanted to impress people, id mimic your signature.
> 
> 
> im here to discuss and learn acoustics, not market a company and sell rooms, room designs, products, etc.



Yawn.....no need for the aggressive attitude, I dont understand why you persist with it in almost every post


Dennis has provided almost unlimited advice, free of charge to many, many builds....some respect of his position both within the industry and within AVS would be appreciated


His work speaks for itself, a more constructive dialogue would be appreciated


----------



## dannut

Yeah, arguing about absorption. Look at the brigh side - waay better then arguing about cables!

Speaking of which, has the ISO standard calculating absorption/scattering coefficients been already revised, based mr. Sauro's research? We need our sabins to be correct for our models! (or not really, fudging is fun)


----------



## localhost127




> Quote:
> Originally Posted by *nickbuol* /forum/post/21278383
> 
> 
> This ought to be interesting. Mr. Pink Fluffy



did you build your porous corner LF traps as of yet? working out for you?


it's clear from your 'jab' at me you likely did not go with a lower flow-resistivity material.


----------



## pepar

This point has been made before - not everybody has space for bass traps, and even less people have space for the pink fluffy kind.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21279237
> 
> 
> This point has been made before - not everybody has space for bass traps,



...



> Quote:
> Originally Posted by *nickbuol* /forum/post/21109400
> 
> 
> I found some mineral wool today while out and about over lunch, but I couldn't find out if it would work for super chunk bass traps





> Quote:
> Originally Posted by *nickbuol* /forum/post/21127619
> 
> 
> Personally, I'm going with straight up, known to work, 703 panels and super chunk bass traps. They work for sure, and I've not afraid to build them.



this is the acoustical treatments master thread. if they have design constraints of which they are not able to apply a treatment, then why does it matter in this thread?


----------



## pepar

Quit taking differing opinions personally.


----------



## Dennis Erskine

Reverberant Field = The area, away from a sound source, where reverberation is louder than the direct sound from the sound source. Fully random, homogeneous reverberent field is a subset of reverberant field.


I suggest Architectural Acoustics (M. David Egan) or Salford University.


Let us also remember that people who sell things, are evil, wicked, greedy, and always self centered and self serving. To get even with these evil peddlers, let's all agree to buy absolutely nothing from anybody until, let's say, January 31st of 2012.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21279650
> 
> 
> Reverberant Field = The area, away from a sound source, *where reverberation is louder than the direct sound from the sound source.* Fully random, homogeneous reverberent field is a subset of reverberant field.
> 
> 
> I suggest Architectural Acoustics (M. David Egan) or Salford University.





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21276458
> 
> 
> A reverberant field does exist in a small room ... *just not a fully random homogeneous one.*



i'm sorry - but while your definition of 'reverberant field' is indeed true, it does not provide objectivity to the fact that such reverberant field still does not develop in a small acoustical space. there is no critical distance in a small acoustical space. there is no point where the reverberation is louder than the direct source in a small acoustical space.

*your recommendation for literature is for large acoustical spaces* ... easily confused and the very reason i continue to bring up such a topic - people mixing terminology, statistical calculations (RT60), and physics of large acoustical spaces with that of small acoustical spaces which are not applicable, and of which many here are constrained to.


----------



## Dennis Erskine

You need to get into more small rooms (start with a shower stall).

In re Egan ... correct. It was suggested I do such a book as a PhD project; but, I'll leave it an eager student.


----------



## Brad Horstkotte

Decay times do exist and are measurable in small spaces, and can be changed via absorption - so I guess I've always been confused by the assertion that reverb doesn't exist in small spaces / RT60 can't be used.


----------



## Dennis Erskine

That definition came from a respected Acoustics text and corresponds with two other texts. Have a good day. With the characteristics of the responses from people who wish to hide behind their anonymity, there was no way I was going to express a definition which could not have citation.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21280319
> 
> 
> That definition came from a respected Acoustics text and corresponds with two other texts. Have a good day. With the characteristics of the responses from people who wish to hide behind their anonymity, there was no way I was going to express a definition which could not have citation.



anonymity has nothing to do with the fact that you are simply mistaken regarding your assertion that a reverberant sound-field exists in a small acoustical space. instead of accepting this (hey, we all learn something new everyday!) you simply diffract around it. the new excuse is 'anonymity'. guess what, my name, date, height, weight, etc- do not change facts, physics, nor acoustics. (nor does my "OCD", as you call it - change facts).


you still do not acknowledge how the values via the product spreadsheet you provided (via ISO 17497-1:2004) in post #8294 do not directly translate into small acoustical spaces (where the treatments are being installed) - due to the small acoustical space lacking a reverberant sound-field (unlike the environment/lab of which the treatment was tested).


maybe i can turn my home theater into an ISO 17497-1:2004 lab - since, after-all, my room contains a reverberant sound-field ???


and i still await your claim (regarding your provided definition in post #8308) on how you can provide (via objective measurements) _"where reverberation is louder than the direct sound from the sound source"_ in a small acoustical space. it's a shame that i somehow know this, considering i have not _"put down the slide rule, get out of the office, and actually build (and measure) a hundred or so rooms."
_

it's unfortunate when such mistaken uses of definitions and formulas meant strictly for large acoustical spaces are being incorrectly applied to small acoustical spaces - and even more unfortunate when one attempts to draw attention to such facts, that it is referred to a 'flash mob'.


signed, _"an eager student."_


----------



## Roger Dressler




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21280165
> 
> 
> To repeat…there is no appreciable reverberant sound field in a small acoustical space – a fundamental characteristic that is one of the defining characteristics that distinguish the small acoustical space from a large acoustical space.



That ought to come as quite a blow to Dr. Toole. wrt Chapter 22.3.4 Other Surfaces—Reverberation Time, from the book: Sound Reproduction. He's using acoustic treatments to treat what doesn't exist.


Now when it comes to diffuse sound fields, they indeed do not exist in small rooms.


----------



## localhost127




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/21280889
> 
> 
> That ought to come as quite a blow to Dr. Toole. wrt Chapter 22.3.4 Other SurfacesReverberation Time, from the book: Sound Reproduction. He's using acoustic treatments to treat what doesn't exist.



does Toole by chance provide objective measurements of his example room such where reverberation is louder than the direct sound from the sound source?


----------



## Roger Dressler




> Quote:
> Originally Posted by *localhost127* /forum/post/21281791
> 
> 
> does Toole by chance provide objective measurements of his example room such where reverberation is louder than the direct sound from the sound source?



What, you don't have his book?


----------



## localhost127




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/21281919
> 
> 
> What, you don't have his book?



not physically - but it is on SCRIBD for reference.
http://www.scribd.com/doc/50043523/1...G-OUT-THE-ROOM


----------



## pepar

Thanks for that link.


----------



## ah7aeGe1ei

I am also interested in the question Pam asked about the rear wall in a 7.1 setup. I will likely use duct wrap on the front wall and below ear level on the side walls. The consensus seems to be nothing on the rear walls or ceiling - correct?


Another question - A non-perf screen reflects quite a bit of sound, but does it pass enough to acoustically treat the wall behind it?


Dennis


----------



## Roger Dressler




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21282701
> 
> 
> Diffuse and semi-diffuse sound fields can indeed exist in a small acoustic space, although when the term diffuse is used, it is will not be homogeneously and statistically diffuse over the entire space.



Agreed. So, across a range of rooms, we may find a continuum between perfectly diffuse and semi-diffuse sound fields, just as we may find perfectly reverberant and semi-reverberant sound fields. Seems reasonable.



> Quote:
> *You can repeat the claim as many times as you like*, but it does not change the fact that a small acoustical space is characterized below the Schroeder (Davis) critical frequency, fc, by the presence of LOCALLY variable regions of low and high pressure low frequency modal behavior, and above fc by localized sparse specular behavior. And specular reflections can indeed be identified and resolved as vectors exhibiting both magnitude and direction, unlike the statistically random well- mixed reverberant field that cannot be so resolved.



I made no claim on this topic.


----------



## pepar

Does this conclude the lecture period?


----------



## BRAD S

Exhausting to read....


Also, it appears AVS has it's very own Mr. Tool!


perhaps a couple


----------



## localhost127




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21284042
> 
> 
> The point of this reply is not to become mired in a personal dispute. Rather it is to bring attention to the problems that the colloquial use of ‘rigorously’ defined terms has in contributing to needless confusion and obfuscation of what should otherwise be a fairly straightforward and objective discussion.



thanks for taking the time to explain it, dragon. it makes much more sense now - and i think such information is really necessarily considering the standards that many absorbers are tested under, and such 'absorption coefficient' values are determined.


i see a consistent flow of people directly quoting the absorption coefficients on Bob Gold's absorption coefficient page, without so much as taking a few moments to even understand just what those values mean and whether such values are directly applicable into a small acoustical space like many rooms of which the treatments are being procured for. there is a consistent assumption that such values are "percentages" - and i have YET to see anyone within this sub-forum as of late (even the experts who design hundreds of rooms! - who really should know such foundational information) even raise the question as to just what those values mean (and, what does a value GREATER than 1.00 even mean, and how are such values achieved?).


thanks for handing such information on a silver platter - i haven't seen many others here take the time to transfer such knowledge that really is fundamental to how we choose and apply treatments in a small acoustical space.


----------



## localhost127




> Quote:
> Originally Posted by *Roger Dressler* /forum/post/21283649
> 
> 
> Agreed. So, across a range of rooms, we may find a continuum between perfectly diffuse and semi-diffuse sound fields,



we all cant afford to have a room like Blackbird Studio C - nor do we have the forklifts required to roll in such diffusers that are effective across the entire specular band.
























edit: and people here have physical design constraints giving up 8inches from their boundary for specular reflection absorption --- what are they going to say when we ask them to give up 3ft on each side for diffusers!


----------



## Dennis Erskine




> Quote:
> (even the experts who design hundreds of rooms! - who really should know such foundational information) even raise the question as to just what those values mean (and, what does a value GREATER than 1.00 even mean, and how are such values achieved?).



Actually, it was. I believe in 2004. About the same as an ETC/ETG/decay discussion was had (along with the problems with those measurements.)


While I suspect many are not willing to give up 14' of wall depth, I would equally suspect they also don't have a $3000, semi-annually calibrated microphone to measure some of the impacts discussed.


Have a nice day.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21284826
> 
> *Actually, it was. I believe in 2004.* About the same as an ETC/ETG/decay discussion was had (along with the problems with those measurements.)
> 
> 
> While I suspect many are not willing to give up 14' of wall depth, I would equally suspect they also don't have a $3000, semi-annually calibrated microphone to measure some of the impacts discussed.
> 
> 
> Have a nice day.



if you had the discussion and were aware in 2004 that such absorption coefficient values measured in reverberation rooms are not directly applicable to small acoustical spaces (of which the treatments are generally procured for) - then why on earth did you target me for raising the very same points! is the information somehow not relevant in 2011? do reverberant sound fields not exist in small acoustical spaces in 2004 but suddenly do in 2011? do you still believe reverberant sound-fields exist in small acoustical spaces, regardless of what has been presented?


if you had the discussion in 2004, then why wouldn't you at least use your expertise and knowledge of past discussions/debates to help "fill in the gaps" regarding the subject? why do you not raise the importance of taking the time to understand such values when they are blatantly presented on this subforum by many user's quoting Bob Gold's absorption coefficient page?


and you conveniently cut-off my quote, let me repost it for you:



> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> and i have YET to see anyone within this sub-forum *as of late* (even the experts who design hundreds of rooms! - who really should know such foundational information) even raise the question as to just what those values mean (and, what does a value GREATER than 1.00 even mean, and how are such values achieved?).


----------



## KNKKNK




> Quote:
> Originally Posted by *BRAD S* /forum/post/21284628
> 
> 
> Exhausting to read....



Agreed slightly prolix! However, an entertaining example of repetitive verbosity, reverberating undampened in a resounding mode adequate to interfere with the intelligibility of the topic's quintessence, and astonishingly occurring irrespective of the apparent deficiency in solid boundaries archetypally accepted as a prerequisite to initiate such resonance.


----------



## pepar




> Quote:
> Originally Posted by *KNKKNK* /forum/post/21285088
> 
> 
> Agreed slightly prolix! However, an entertaining example of repetitive verbosity, reverberating undampened in a resounding mode adequate to interfere with the intelligibility of the topic's quintessence,



I think that's from the increase in decay time from everybody leaving the room.


----------



## Roger Dressler




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21284042
> 
> 
> While one might find it a "reasonable" assumption, it is in fact not correct.



If you want to tell Dr. Toole he is misusing the terminology, go ahead. Enjoy.



> Quote:
> I am sorry, but you have indeed (intentionally or unintentionally) done that. Specifically as the locally variable scenario that defines a small acoustical space stated above is the antithesis of a “perfectly reverberant” sound field, which you have twice declared to exist in small acoustical spaces.



I merely quoted Dr. Toole. That was my first post. In it I made no claim one way or the other.


----------



## Dennis Erskine

It is perhaps time to bring some of the information in this thread down to earth. Many of the concepts discussed in the past several weeks are not new topics to this forum. Decay times, energy-time, decay, ITDG (Initial Time Delay Gap), absorption coefficients, and STC discussions have come and gone since 2000. We can revisit a few of those in the context of what the vast majority of AVS Forum members are wanting to achieve.


STC (Sound Transmission Class) - Like many commonly available metrics, this metric is not suitable for use in a music or cinema playback space. It is a single number representing the relative (term used loosely) sound attenuation property of a material or a constructed barrier. Problematic issues include the limited frequency range (125Hz to 4kHz) and the fact the single number doesn't reveal the frequencies within that range the construct is most, or least, effective. Given two doors (or walls) with the same STC value, each can have wildly different attenuation properties within the range under test. (Equally problematic is most NVLAP certified facilities cannot accurately measure attenuation below 80Hz to 50Hz.) Equally problematic is the number can be easily cooked. The coincident dip can be engineered to appear above 4kHz and the resonance frequency lowered below 125Hz which serves to create a better STC rating. While that is a good thing where STC makes sense, it is a bad thing in spaces where the real concern is from 20Hz to 20kHz. [Note: STC values are expressed in decibels which are logarithmic.] The catalog of STC values for materials, composites, wall and floor constructs is vast. Many forests have given their lives to the publication of STC values. None-the-less, what is really needed by the enthusiast and hard core DIYer are Transmission Loss (TL) values. When something' is tested to generate the STC value, the lab actually measures TL at a minimum of 16 frequencies. Many labs actually provide the TL numbers at 50Hz intervals down to the flanking limits of their facility. Those are the numbers you want to get your hands on. For a manufactured product (like a door or window), the manufacturer (at least a legitimate one) will be happy to provide that data from the certified lab test report. As an aside, there is an OITC rating standard which considers frequencies down to 80Hz. So herein lies a problem the most commonly available data for the attenuation value of a barrier is not appropriate for music/cinema spaces, which is precisely what this forum is all about. So what to do? You really need to seek advice and direction from someone who has several years of experience in sound isolation/attenuation under real world conditions for guidance (Ted White is an excellent resource on this forum although he is among those very evil people who here who sell stuff). Why real world? What you see and get in the lab are very closely controlled environmentswhat you see in real homes and construction in the field are radically different. Lab tests don't have to deal with HVAC, plumbing, electrical, etc.

So, why do you care about sound attenuation? The most common concern is not disturbing others. Clearly, that could make or break your use of your carefully crafted, sneaking money out of the cookie jar, project. But, there is a more important reason. The softest sound on a sound track is 22dB. The average ambient background noise in a quiet home is 33dB. If your noise floor in your room is 22dB or higher, you have to raise the volume so the softest sounds are above the noise floor. Generally, that is a 6 to 8 times increase in volume. Not a big deal at low levels; but, 6 times louder means people on the screen are yelling at you (so is your spouse, kids, etc.), explosions, train wrecks, and other effects (including the cannon in the 1812 overture) are 6 to 8 times louder and can lead to blown drivers and clipping). All of that exacerbates this whole business of not waking the baby. An ideal target is to achieve an NC or NR of 20. Tough to do and if you want to see if you made it, plan on spending over $3,000 just on the microphone to measure it (common, not professional use, test equipment will often have internal noise above that threshold as well and cannot provide accurate results.) So, what do to. Get the TL numbers from published STC tests and seek advice from someone like Ted White. The data you really need is not published (at least not widely) and the real data comes from experience in the field.


ENERGY-TIME (ETG/ETC/ITDG). The more recent discussion of these topics resulted in a lot of arm waving including a remark if this is so important, why hasn't it been discussed before?. Well it has been. One forum user (Jamin) found one such discussion in the forum dated in 2004. It is a yardstick, it is important; but, on the other hand it is absolutely not the only yardstick that must be used to properly calibrate your acoustic space. A proper Energy-Time-Graph (ETG), will reveal the rate of sound decay at the microphone position, the smoothness of that decay, the Initial Time Delay Gap (ITDG) and the existence of early reflections (and their strength). However, other than the results often being misinterpreted, there is a serious failing in the measurement will not reveal decay rate by frequencyit simply shows the aggregated decay of all frequencies (subject to the microphone and the test equipment utilized). Ideally, you want all frequencies to decay at the same rate throughout the audio spectrum. (Sean Olive demonstrated a case where the ETG was beautiful; but, the sound was horrid due to a very wide variation in the decay by frequency.) It is a valuable tool; but, it is one of many which must be used and it most certainly will not reveal the decay properties of the space. The ITDG is revealed by a properly set up ETG test (one can also determine processor latency). The ITDG is the delta between the arrival/intensity of the direct sound and the arrival/intensity of the first reflected sound. It is this delta which provides one of the many cues used to provide us a sense as to the size of the physical space. While intensity of the first reflected sound can be affected by acoustic treatments in the absence of very sophisticated ambiance extraction processes and front-side-wide speakers, changing delay (other than complete eradication of the first reflection) cannot be achieved with passive wall treatments. The other alternative is to increase the path length between the source, boundary, and listener. The ITDG is problematic. Impulses from test equipment do not have an ITDG; however, recorded music does have an ITDG, particularly music recorded in a live venue. The ITDG at the microphone is recorded with the sound track. On playback, the ITDG of the playback space and the ITDG of the original recording are overlaid. In the process of developing digital editing, the question of managing that against the playback space was raised; but, at the time, way, way outside the scope of the project and the technology at the time (not to mention the potential of umbrage as a result of mucking with the artists' original work). Herein rests one (of the many) arguments for very dead spaces in multi-channel (more than three speakers) playback spaces. On the other hand, our mechanisms of listening perception are well adapted to sort out this problem. Again, ETG is an important yardstick. It is not the only yardstick required, is subject to misinterpretation and, in some circles, perhaps over emphasized.


Absorption Coefficients/Incident Angles. (Ever heard of Millington Values? We won't go there.) Discussions with respect to this subject have been raised over the past many years. Those newer to the forum certainly wouldn't be expected to realize this. Those who have been with the forum for many years are likely tired of hearing about it. I also suppose if we need to be entirely accurate, we need to say sound absorption coefficient to make it absolutely clear we're not discussing Optical, electromagnetic or other absorption/attenuation coefficients. As has been mentioned, coefficients are not percentages, nor can a coefficient technically be greater than 1. So be it. (The test method used accounts for the flat surface area of the material under test but ignores the exposed edges of the material which can result in the >1 result.) As is true with STC testing, the lab environment in no way matches the environment in a small room, large room, or gigantinormous room. This test environment (a reverberation chamber) measures the spectral absorption characteristics of a material without respect to the angle of incidence of the sound against the material. We must recognize the amount of energy absorbed will be affected by the angle of incidence (head on vs a glancing blow). Furthermore, this testing does not reveal anything about the material's impedance since random incidence testing can only measure energy. Knowing the impedance of a material is very important. Without knowing the impedance, you cannot model the net absorption characterisics of, say, 2 of 1.5PCF fiberglass over ½ gypsum board! The alternative to random incidence testing of a material is normal incidence testing which is conducted using a impedance tube. Whether using a 1 or 2 microphone method, normal incidence testing results can vary. The only truly accurate way to determine normal incidence values is to use a scanning laser Doppler vibrometer (SLDV) a device you may find at some universities, at DOE, NIST, the U.S. Navy and at least one private company (that I know of). None-the-less, there are several problems here. First, we can find the published absorption coefficients of darn near every material on planet earth. Second, normal incident test results are not (if at all) published although you may find them for materials used in aircraft and automobiles. In effect, Absorption Coefficients are what we have, deal with it. While a lot of lip service has been provided about the inappropriate use of absorption coefficients in small acoustics spaces, the reality is normal incidence values are even less useful. (Cox and D'Antonio developed a method to approximate normal incidence values from random incident data.) In small rooms certainly, and even in auditoria, very little of the total sound energy is normal incident to the material. There is a modeling method used for small acoustic spaces and even larger auditoria, known as Statistical Energy Analysis (SEA). In modeling various tools can be used. These include geometric fitting, ray tracing, boundary element analysis, and so forth. For small spaces (automobiles, aircraft, submarines, etc.) any number of these methods are utilized in models to (a) determine the quantitative energy amounts by incident angle and (b) approximate energy absorption (frequency shift, phase shift, etc.) based upon two criteria: interpolation and the use of empirical data based upon past experience. Of these, historically empirical approaches have been the more accurate (comparing predicted vs actual results). So, what's the answer here? Frankly, absorption coefficients are what we have. In the absence of a body of empirical data based upon experience or very specific (and expensive testing) there are really two choices: (1) put the stuff in and move it around until you like the sound or the room measures to your satisfaction; or, (2) seek expert help. For a performance critical environment, expert help is the better direction and there are a very large number of such individuals and companies you can seek out.


----------



## vinyl

Such patience Dennis ...


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## Brad Horstkotte

Thanks Dennis.


My thought re: absorption coefficients is that while the absolute values may not mean much outside the test lab, they are what we have as you said, and are still useful for material comparison purposes (such as when one can't source material "A" locally, the good old Bob Gold chart helps us determine whether options "B", "C", "D" that are available locally are suitable substitutes).


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290056
> 
> 
> It is perhaps time to bring some of the information in this thread down to earth. *Many of the concepts discussed in the past several weeks are not new topics to this forum.* Decay times, energy-time, decay, ITDG (Initial Time Delay Gap), absorption coefficients, and STC discussions have come and gone since 2000. We can revisit a few of those in the context of what the vast majority of AVS Forum members are wanting to achieve.


*no one claimed it is 'new knowledge'* - especially since the knowledge most certainly was presented decades ago, well before this 'year 2000 conversation'. the fact is, just because something was discussed at one point in time YET such information failed to trickle down and become "common knowledge" within the forum and community, only shows the failure.



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290056
> 
> 
> ENERGY-TIME (ETG/ETC/ITDG). The more recent discussion of these topics resulted in a lot of arm waving including a remark if this is so important, why hasn't it been discussed before?.



what is boils down to is that *it is a simple tool with specific uses* - and people feel the need to attack it due to it not being a tool that _"does everything"_ ... yet, the same members do not apply the same scrutiny to other tools which clearly do not "do everything". fact.


for the usefulness of a user's goal of attenuating/absorbing early reflections (easily the most popular form of 'treatment' questions raised on this subforum), the ETC is more than sufficient to identify such early specular reflections, their arrival time and gain - as well as gain once the absorber (or whatever treatment) has been placed. this is specifically such a scenario of which the ETC is recommended.





> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290056
> 
> 
> Well it has been. One forum user (Jamin) found one such discussion in the forum dated in 2004. It is a yardstick, it is important; *but, on the other hand it is absolutely not the only yardstick that must be used to properly calibrate your acoustic space.*



and pray-tell, who here is insisting that a single tool in the toolbox is to be used to fully calibrate an acoustical space? ridiculous and more distractions to what has actually been stated.




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290056
> 
> 
> As has been mentioned, coefficients are not percentages, nor can a coefficient technically be greater than 1. So be it. (The test method used accounts for the flat surface area of the material under test but ignores the exposed edges of the material which can result in the >1 result.) As is true with STC testing, the lab environment in no way matches the environment in a small room, large room, or gigantinormous room. This test environment (a reverberation chamber) measures the spectral absorption characteristics of a material without respect to the angle of incidence of the sound against the material. We must recognize the amount of energy absorbed will be affected by the angle of incidence (head on vs a glancing blow). Furthermore, this testing does not reveal anything about the material's impedance since random incidence testing can only measure energy. Knowing the impedance of a material is very important. Without knowing the impedance, you cannot model the net absorption



good to see you came around and we are finally in agree-ance, Dennis - regarding the ISO standards you proposed with the perf-sorber measurements and the follow-up commentary i presented that it is not directly applicable in small acoustical spaces (which are dominated by specular reflections/angle-of-incidence) - due to lack of a reverberant sound-field...and that such "values" are not to be presented (or assumed, as many novices may do) as percentages.

http://www.avsforum.com/avs-vb/showt...8#post21274898 


your quote of the thread from 2000/2004 directly contradicts your statement regarding reverberant sound-field in small acoustical spaces, but im glad to see it looks like we're on the same page now.


----------



## localhost127




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21290284
> 
> 
> Thanks Dennis.
> 
> 
> My thought re: absorption coefficients is that while the absolute values may not mean much outside the test lab, they are what we have as you said, and are still useful for material comparison purposes (such as when one can't source material "A" locally, the good old Bob Gold chart helps us determine whether options "B", "C", "D" that are available locally are suitable substitutes).



he didn't say that, i did ( http://www.avsforum.com/avs-vb/showt...8#post21274898 ) - in my response where i directly quoted the 2nd paragraph on Bob Gold's Absorbtion Coefficient page).


i dont mind if you continue to try to spin the conversation (or cheerlead for someone you look up to regarding the topic) ... just as long as the information is out there and hopefully it starts becoming absorbed (no pun) by the community ... versus having to get into such debates in the future every time the topic is brought up.


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## Dennis Erskine




> Quote:
> Dennis - regarding the ISO standards you proposed with the perf-sorber



Selective reading on your part. I didn't propose that, I simply reported the test results obtained by the patent holder.



> Quote:
> no one claimed it is 'new knowledge' -



Again, selective reading filter was engaged. I didn't claim new knowledge. Note the highlighted (by you) "on this forum".



> Quote:
> ETC is more than sufficient to identify such early specular reflections



Selective filter again... it is not.



> Quote:
> and pray-tell, who here is insisting that a single tool in the toolbox is to be used to fully calibrate an acoustical space? ridiculous and more distractions to what has actually been stated



You're simply being argumentative. Further, I never said a coefficient was a percentage. Not interested in further discussion as a result.


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## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290802
> 
> 
> You're simply being argumentative. Further, I never said a coefficient was a percentage. Not interested in further discussion as a result.



and i merely pointed out the easy misconception. you presented absorption coefficient values to a novice without so much as stating what they mean.


i suggest you go back and re-read my original post of which started this whole discussion - and the specific commentary i quoted from Bob Gold to provide in some clarity or context (adding on) to your original statement.

http://www.avsforum.com/avs-vb/showt...8#post21274898 


i understand the frustration of you being misguided on the whole 'reverberant soundfield in small acoustical spaces' (we all continue to learn new information everyday) - but there is no need to go off further on distractions to hide that fact. and distractions are all you can provide (what does STC have to do with this conversation?).


...and speaking of coefficients, you still haven't provided diffusion coefficients for the perf-sorber which you continually refer to as a 'diffuser'. i'd love to see them.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290802
> 
> 
> Again, selective reading filter was engaged. I didn't claim new knowledge. Note the highlighted (by you) "on this forum".



well, you're right about that, Dennis! my apologies for not searching back to the year 2000-2004 on AVSForums when i stated that such and such as never discussed. ill revise my statement to: "such and such hasn't been commonly discussed at all in the past 7-11 years".


fair enough -


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## Dennis Erskine




> Quote:
> ...and speaking of coefficients, you still haven't provided diffusion coefficients for the perf-sorber which you continually refer to as a 'diffuser'. i'd love to see them.



Yes, I did.


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## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21291269
> 
> 
> Yes, I did.



i scanned through all of your commentary after you posted the .PDF in post #8924 ( http://www.avsforum.com/avs-vb/showp...postcount=8294 ) , but still unable to find the data.


if not, it's not a big deal - was just curious,


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## Dennis Erskine

See plot in red? That is labeled as "scattering coefficient".


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## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21291405
> 
> 
> See plot in red? That is labeled as "scattering coefficient".



scattering coefficient and diffusion coefficient are two entirely separate concepts.



http://imgur.com/r1aLA.png%5B/IMG%5D




http://imgur.com/JC5cD.png%5B/IMG%5D



quoted from:

Acoustic Absorbers and Diffusers: Theory, Design and Application, Second Edition: (Cox & D'Antonio)
http://www.amazon.com/Acoustic-Absor.../dp/B001Y35IHW 



> Quote:
> *4.4 The diffusion coefficient*
> 
> 4.4.1 Principle
> 
> The general method for evaluating diffuser quality is as follows. First, the scattering from a surface is measured or predicted in terms of a polar distribution, as discussed in Section 4.1. Then the diffusion coefficient is a frequency dependent, single figure of merit derived from the polar distribution. This is evaluated in one-third octave bandwidths, which has the advantage of smoothing out some of the local variations in the polar responses, so the diffusion coefficient is based more on the overall envelope.There have been various statistical operations suggested to calculate a diffusion coefficient from the polar distributions: standard deviation, directivity, specular zone levels and spherical harmonics, percentiles and autocorrelation.
> 
> 
> In any such data reduction, there is a risk of losing essential detail. It has been shown that the autocorrelation coefficient seems to offer significant advantages over other published statistical techniques.The autocorrelation function is commonly used to measure the similarity between a signal and a delayed version of itself; looking for self similarity in time. It is alsopossible to use the autocorrelation to measure the scattered energy's spatial similarity,with receiver angle. A surface which scatters sound uniformly to all receivers will produce high values in the spatial autocorrelation function; conversely, surfaces which concentrate reflected energy in one direction will give low values.





> Quote:
> *4.5 The scattering coefficient*
> 
> 4.5.1 Principle
> 
> The principle of a scattering coefficient is to separate the reflected sound into specular and scattered components. The specular component is the proportion of energy which is reflected in the same way as would happen for a large plane surface. The scattered components give the energy reflected in a non-specular manner. This is illustrated in Figure 4.22. The coefficient has a clear physical meaning and the definition is very useful for geometric room acoustic models, because these tend to have separate algorithms dealing with specular and scattered components. Therefore the separation of terms mimics the modelling methods. With this definition it is then possible to define a scattering coefficient, s, as the proportion of energy not reflected in a specular manner.This definition takes no account of how the scattered energy is distributed, but assumes that in most room acoustic applications there is a large amount of mixing of different reflections. Therefore, any inaccuracies that arise from this simplification will average out. This is probably a reasonable assumption for the reverberant field, where there are many reflections. However, it could well be troublesome for the early soundfield, where the impulse response is dominated by a few isolated reflections and the correct modelling of these is essential for gaining accurate predictions. Section 4.4.1has already illustrated how scattering coefficients can give misleading results for the first order reflections from redirecting surfaces.




http://imgur.com/OdqU3.png%5B/IMG%5D





google books has a few pages available, but many are not.

http://books.google.com/books?id=jYB...4.1%20&f=false 


a flat boundary (angled slightly) can have a high scattering coefficient, but clearly would not have a high diffusion coefficient.


disregard all of this - i'd prefer not to go down the path of what just happened regarding 'reverberant space'...but there is a significant difference between the two coefficients and test methods.


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## Dennis Erskine

My error. You asked about diffusion, I provided the "scattering" data which is what the patent holder has reported. If there is any other data, you'd have to determine that from the patent holder or test the material yourself...and I am very much aware of the differences between the two.


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21291495
> 
> 
> My error. You asked about diffusion, I provided the "scattering" data which is what the patent holder has reported. If there is any other data, you'd have to determine that from the patent holder or test the material yourself.



no worries. thank you -


----------



## sdurani




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21290056
> 
> 
> ENERGY-TIME ...there is a serious failing in the measurement will not reveal decay rate by frequencyit simply shows the aggregated decay of all frequencies (subject to the microphone and the test equipment utilized). Ideally, you want all frequencies to decay at the same rate throughout the audio spectrum. (Sean Olive demonstrated a case where the ETG was beautiful; but, the sound was horrid due to a very wide variation in the decay by frequency.)



Agreed, the basic measurements are spectrally (and directionally) blind. But, just as you can hold up panels around the mic to make the measurements directional, you can bandpass filter the measurements to see what is happening spectrally. To that end, forum poster Nyal Mellor in his recent paper described using (bandpass filtered and smoothed) ETCs to not only check decay throughout the spectrum but also check consistency between the left and right speakers.


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## Dennis Erskine

Thanks for bringing that up Sanjay. That is certainly a way to check spectral decay.


----------



## tova

Is there any similar acoustical measurement standards for home theaters?


/Tova


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## mtbdudex




> Quote:
> Originally Posted by *tova* /forum/post/21294142
> 
> 
> Is there any similar acoustical measurement standards for home theaters?
> 
> 
> /Tova



Hmmm, this makes me curious what Home Theatre designers use or ignore for HT spaces from the general room acoustical parameters given in ISO 3382.

If other acoustical parameters are used I'd like to know those also - if already discussed/posted a link much appreciated.

(this from ARTA user manual)










I asked similar Q in this Nov-28-2011 thread, hopefully G-Rex can find those and post in that thread:
http://www.avsforum.com/avs-vb/showt...3#post21270283 


> Quote:
> 
> 
> 
> Quote:
> Originally Posted by *G-Rex* /forum/post/21268547
> 
> 
> I kind of dropped off the thread due to some medical issues. Thought I would give some data now that I'm back. Terry's after treatment measurements of my theater show:
> 
> 
> Audible early early reflections (sound stage accuracy ). None. Rating : Excellent
> 
> 
> Average Reververation Time (fidelity and lack of distortion) 0.22 seconds Rating: Excellent
> 
> 
> Speech Transmission Time (Dialogue intelligibility) 0.83 seconds Rating: Excellent
> 
> 
> The room is not overly dead but a bit more dead than live indicated by the 0.22 number. This test was done with the smaller 96" wide 1:85:1 Stewart ST 130 non AP screen in place. My guess would be that the safer thing to to here would be to go 120" wide 2:35:1 screen that is not acoustically perforated. Dennis, and others, If your still monitoring this thread do you agree?
> 
> 
> 
> 
> G-Rex;
> 
> as sharing/learning could you post the graphs/charts behind the (3) criteria above?
> 
> 
> 1) Audible early early reflections; I take it ETC was used
> 
> 2) Average Reververation Time; was 1/3 octave readings taken?
> 
> 3) Speech Transmission Time; what graphs/charts used for this?
> 
> 
> Thanks.
Click to expand...


----------



## localhost127




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21295330
> 
> 
> Hmmm, this makes me curious what Home Theatre designers use or ignore for HT spaces from the general room acoustical parameters given in ISO 3382.
> 
> If other acoustical parameters are used I'd like to know those also - if already discussed/posted a link much appreciated.
> 
> (this from ARTA user manual)



mtb,

tread carefully when reviewing criteria for large acoustical spaces - versus small acoustical spaces of which many of us here are constrained. there is no 'reverberation' in a small acoustical space, nor are there 'echos' - which are generally dictated by >80ms time-arrivals after the direct signal (ignoring gain for simplicity). does anyone here have a large enough space such that their rear wall is 45ft (~90ft round-trip : ~80ms) behind the listening position?


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## Dennis Erskine

80ms is not a hard and fast threshold. There an intensity component. Small rooms can echo; however, they are more likely to ring or reverberate.


FUSION ECHO THRESHOLDS

Haas ~1951! speech 30–40 ms ‘‘echo annoying’’

Lochner and Burger ~1958! speech 50 ms lead and lag ‘‘equally loud’’

Schubert & Wernick ~1969! noise

a! 20-ms duration 5–6 ms lead and lag ‘‘equally loud’’

b! 50-ms duration 12 ms

c!100-ms duration 22 ms

Ebata et al. ~1968! clicks 10 ms fused image at center of the head

Freyman et al. ~1991! clicks 5–9 ms lag heard on 50% of trials

Yang and Grantham ~1997a! clicks 5–10 ms lag clearly audible on 75% of trials

Litovsky et al. ~1999! clicks 5–10 ms lag clearly audible on 75% of trials

DISCRIMINATION CRITICAL THRESHOLDS

Freyman et al. ~1991! clicks 5–9 ms d851

Yang and Grantham ~1997b! clicks 5–10 ms discrimination 75% correct

Litovsky et al. ~1999! clicks 5–10 ms discrimination 75% correct

LOCALIZATION CRITICAL THRESHOLDS

Litovsky et al. ~1997b! clicks 11.4 ms lead location chosen on 75% of trials

Litovsky et al. ~1997a! clicks 8 ms lead location chosen on 75% of trials


---

-Echo threshold (i.e., temporal delay producing ~50% perception of discrete lag in “lead-lag” stimulus)

is modulated by the stimulus context; for impulsive signals, baseline echo thresholds of 5-10 ms are

“built up” to 10-25 ms by repetition of the lead-lag stimulus (e.g., Clifton and Freyman, 1989)

---
http://symphony.arch.rpi.edu/~braasj...raasch2005.pdf 

---

 

Document1.pdf 30.8115234375k . file


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21299669
> 
> 
> 80ms is not a hard and fast threshold. There an intensity component.
> 
> ---





> Quote:
> Originally Posted by *localhost127* /forum/post/21299416
> 
> 
> which are generally dictated by >80ms time-arrivals after the direct signal *(ignoring gain for simplicity)*.




try and keep up.


----------



## mtbdudex




> Quote:
> Originally Posted by *localhost127* /forum/post/21299416
> 
> 
> mtb,
> 
> tread carefully when reviewing criteria for large acoustical spaces - versus small acoustical spaces of which many of us here are constrained.



I do realize that, my point is I want to find or establish a table for "Home Theatre small acoustical space relevant acoustical parameters" at a high level:

Subjective aspect item, Description of measurement (Quantity symbol), and desired objective target number/range.


Using that table was a simple visual starter.


With that table, then "why" each acoustical parameter is significant can be further explored and grasped.


If one exists, please share.


Dennis;

Many thx for continue sharing of your knowledge.


----------



## Dennis Erskine

Mike:


Excellent project. I ran across a research paper recently which attempted to address some of what you're looking to assemble. I'll see if I can dig it up. It was actually a good paper ... so many I see have been written by bright folk with considerable knowledge but haven't crossed the threshold from knowledge to understanding. The "why" part is going to be a big challenge and will evoke considerable discussion. At the same time, the interactivity between these various metrics can create quite a puzzle.


If we examine three rooms (6.4m x 4.6m x 4.3m, 3m x 3.5m x 2m, 9.1m x 6.25m x 6.1m) all can be set up to meet the sound criteria provided any number of different bodies (ISO, SMPTE, etc) in one spot. The challenge, however, it not meeing the criteria in one location, it is meeting "acceptable" criteria over a larger listening area. If we accept the definition of a "small room" as being "if you move 1m and the sound changes, you're in a small room"; then, recognizing many of these parameters are interactive with each other, defining the range of "acceptable" criteria. This cannot really be expressed as a range of independent values (ie, if T30 is between x and y, you're good) but rather expressed as if T30 = x, then G must equal z.


Of course, in the end, we know the reference criteria of a 100' x 50' x 20' space, the Academy, ISO and SMPTE reference rooms; but, the real challenge is how then do you engineer a 14' x 27' x 9' space to meet the same criteria over the same relative seating area?


----------



## SoundofMind

Hi guys. I've been lurking on the thread for awhile. I've tried to incorporate some of the basic principles in HT design that I've picked up here and elsewhere on AVSF. Now I'd like to throw this post out there and I'd appreciate any suggestions on things I might do to improve my non-dedicated HT family room. Caveat: we're keeping WAF in mind and greatly favor relatively simple inexpensive fixes.







If it's better to start a new thread I'd be glad to do so and I apologize for the lengthy post. I've attached photos to aid in the discussion.


pic 1: This gives a perspective on the vaulted ceiling and relative position of speakers and MLP. This is a 16’X22’ room with 8’ walls arched to the 12' ceiling peak (3500' cu) which runs from R to L irt MLP. FR/L and MLP form an equilateral triangle measuring 9' on each side. Note the curtains, which were eventually/grudgingly allowed by the wife who loves sunshine and is very partial to simple clean decorating. The room was outrageously lively and bright acoustically with absolurtely no window treatments before. Though not thick, they have an "acoustic"/light blocking lining and there's 17, yup, 17 curtain "panels". Also note that the windows they cover are happily fairly strategically placed, including nearly the entire R side wall and R side first reflection point. I extended them slightly to cover the wall directly behind the FR/L rear ported Dali Helicon 400 towers-see pic 3. The new bigger thicker padded carpet also helps.


pic 2. As you can see, the first reflection point on the L side wall is a bit more of a problem. It features a DSX wide speaker, shelves and a guitar draped with a thick throw. Oh, BTW those are timbre-matched Dali Helicon direct-firing w200 on stands deployed as surrounds and DSX wides. Surround placement is optimized for MC music but also works quite well for film.


pic 4. Behind MLP is a large framed print on the wall. I secretly removed the glass covering it.







To the side of MLP on the back wall there are large windows now covered with curtains. Oh, and I replaced the very tall/wide high back on the zero gravity recliner with a small custom comfy neck/headrest pillow. This worked wonders for the soundstage and surround bubble.


I have some real-time measuring capability in that the subs have built-in SMS, so I used this to place them. They are now midway on front and back walls. The Audyssey Pro Installer kit does summed measurements. See the "before" graphs here . The "after" ones are calculated predictions.


Over the past 3 yrs it's been a long labor of love with an endless series of changes including speaker and sub placement and _lots_ of gear upgrades (say mebbe $10K spent on $20K MSRP worth of sound gear) and A/B sound tests. Most recently I added a second Velodyne DD10 sub, a Denon AVR AVR A100 with Audyssey MultEQXT32 with Pro kit calibration, an Emotiva XPA5 amp and a Denon DBPA100 universal BluRay connected with DenonLink. I must say it sounds really good. The bass is tight, punchy and smooth. The imaging, detail, soundstage width and surround bubble are all quite pleasing.


But I wonder if it can sound even better with some more simple practical things that have reasonable WAF. One thing I'd like to discuss in particular is the effect of the angled ceiling reflections striking MLP. I found that SQ improved markedly as I moved the front speakers away from the front wall (done incrementally so the wife could get acclimated to it, they're now over 3' away). Ditto when I gradually moved MLP away from the back wall; my head is now 32" from the wall when slightly reclined. Some of this I attribute to wall interactions but I think some results from getting the speakers and MLP closer to the mid room peak in the ceiling which I believe results in decreased reflections at MLP. Unfortunately that also makes the sweet spot very very small.


I'm wondering if because of the angled ceiling, rotating the install by shifting the HT cabinet to a corner or onto the R side wall would result in a big improvement in SQ and allow a bigger sweet spot. Or perhaps there is an unobtrusive way to treat the ceiling ("WonderSound Invisible Acoustic Ceiling Paint"?







).


With things where they are, I'm considering what I can do for the L wall first reflection point (WAF alert!) as well as behind the large, rear-ported timbre-matched Helicon c200 CC. So I'm interested in your feedback.


----------



## Irv Kelman




> Quote:
> Originally Posted by *localhost127* /forum/post/21299680
> 
> 
> try and keep up.



It appears you have something to contribute to this discussion but your lack of civility makes it hard to take you seriously.


----------



## pepar




> Quote:
> Originally Posted by *SoundofMind* /forum/post/21302482
> 
> 
> Hi guys. I've been lurking on the thread for awhile. I've tried to incorporate some of the basic principles in HT design that I've picked up here and elsewhere on AVSF. Now I'd like to throw this post out there and I'd appreciate any suggestions on things I might do to improve my non-dedicated HT family room. Caveat: we're keeping WAF in mind and greatly favor relatively simple inexpensive fixes.
> 
> 
> 
> 
> 
> 
> 
> If it's better to start a new thread I'd be glad to do so and I apologize for the lengthy post. I've attached photos to aid in the discussion.



SoM, straight out of the gate, the WAF caveat presents a challenge. No news there, right?










I only have two observations, the ceiling and the hard wall behind the MLP. Do you have measuring capabilities, i.e. calibrated mic and something like REW? I think you are at that point, and having charts and graphs would make your WAF presentation more convincing.


Jeff


----------



## mtbdudex




> Quote:
> Originally Posted by *SoundofMind* /forum/post/21302482
> 
> 
> I'm wondering if because of the angled ceiling, rotating the install by shifting the HT cabinet to a corner or onto the R side wall would result in a big improvement in SQ and allow a bigger sweet spot. Or perhaps there is an unobtrusive way to treat the ceiling ("WonderSound Invisible Acoustic Ceiling Paint"?
> 
> 
> 
> 
> 
> 
> 
> ).



Seeing your room and angled ceiling reminded me of this picture from Ethan Winer's page, You've got a fan there, still seems doable:
http://www.ethanwiner.com/acoustics.html#symmetry 


> Quote:
> A peaked ceiling is better than a flat ceiling because it avoids the echoes and ringing that occur when the ceiling is parallel to the floor. But a peak creates a focusing effect, much like a parabolic dish, which is less than ideal. For this reason it's a good idea to place absorption or diffusion under the peaked portion, as shown in the photo below.


----------



## SoundofMind

Jeff, agreed the WAF is a very limiting aspect. And I'd be doing a dedicated HT build in the basement with no WAF constraint if my SQ results weren't as good as they are with the DSP and the simple interventions I've managed so far. But let's face it, _no_ amount of measuring and graphs will make any difference to her whatsoever. My goodness, this is already the best sounding system the wife (and any visitor for that matter) has heard so I can expect no sympathy for gluing acoustic panels on that pristine white ceiling.


Your point irt measurements is well taken. More complex and extensive measurements would give more useful data but I've been unwilling to invest my limited HT hobby time into the learning necessary for REW. I even tried the far easier plug-and-play OmniMic briefly. But knowing how to do the more complex measurements and more importantly _how to make use of them_ is not going to happen any time soon, becasue of that intrusive "day job" thingy.


My objective here is more along the lines of bringing some experienced eyes (I wish it could be ears) into the room and posing the question:


"What advice might you offer to me about this room given the above circumstances?"


Though "What would _you_ do to improve SQ in this room?" might be interesting too.


----------



## pepar

I'd try to find an artful, but effective absorber for behind the MLP. I have no experience with it, but here is one example .


And anything to get some absorption and/or diffusion on that ceiling ...


----------



## sdurani




> Quote:
> A peaked ceiling is better than a flat ceiling because it avoids the echoes and ringing that occur when the ceiling is parallel to the floor. But a peak creates a focusing effect, much like a parabolic dish, which is less than ideal. For this reason it's a good idea to place absorption or diffusion under the peaked portion, as shown in the photo below.



When you see a parabolic dish, it is usually focusing on a receptor directly in front of it, like a field microphone or a satellite antenna. Does Ethan's advice apply if none of the listeners are directly under the peak in the ceiling, like in SoM's room?


----------



## SoundofMind




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21303248
> 
> 
> Seeing your room and angled ceiling reminded me of this picture from Ethan Winer's page..



Hi. Lets just get this out of the way: those panels are not practical irt WAF!

















Seriously though, thanks for the very interesting info on angled ceilings. If it is indeed focusing reflections like a dish then hopefully they're heading straight down and being diffused and absorbed by the carpet.


I try to get a grasp on the angle of the reflections but it's mind-boggling for me. I'd thought about the sound bouncing around up there in the peak and considered adding a long triangular shaped treatment of some sort to both sides of the beam, tucked into and filling the gap from beam to ceiling and running wall to wall. It would be a pretty big project and I've no idea if something relatively unobtrusive like that would be effective enough to be worth the investment. I guess I'd have to learn the measuring system, measure, construct and mount the treatments and then listen and measure again.


----------



## SoundofMind




> Quote:
> Originally Posted by *pepar* /forum/post/21303282
> 
> 
> I'd try to find an artful, but effective absorber for behind the MLP. I have no experience with it, but here is one example ...



Jeff, I've indeed been considering several options similar to that. That chinese print is on cloth and could be stretched over an acoustic panel. Or I could get a bigger panel with another custom design. This could be fairly easy to experiment with, using a standard panel to do A/B tests before getting a custom one.


----------



## mtbdudex




> Quote:
> Originally Posted by *sdurani* /forum/post/21303351
> 
> 
> When you see a parabolic dish, it is usually focusing on a receptor directly in front of it, like a field microphone or a satellite antenna. Does Ethan's advice apply if none of the listeners are directly under the peak in the ceiling, like in SoM's room?



sdurani, best way - I'm sure you know, is take measurements, use ETC as a tool for reflections, and take the guess work out.


SoundofMind, check out GIK also for acoustic art panels.
http://www.gikacoustics.com/gik_artpanel.html 


> Quote:
> Need acoustic treatment, but want something with that extra touch of class? Need something that performs like the rest of our top-notch panels but makes a decorative statement to improve your WAF (Wife Acceptance Factor) or to impress your clients? We've got just the thing for you - the GIK ArtPanel.


----------



## pepar




> Quote:
> Originally Posted by *SoundofMind* /forum/post/21303373
> 
> 
> I'd thought about the sound bouncing around up there in the peak and considered adding a long triangular shaped treatment of some sort to both sides of the beam, tucked into and filling the gap from beam to ceiling and running wall to wall.



Bingo.


But it's not certain that you need it to be absorption. But your design could allow whatever is needed to be placed there. And an acoustically transparent cover could hide it all. That's where the measuring comes in ... to tell you what is needed.


----------



## SoundofMind




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21303485
> 
> 
> SoundofMind, check out GIK also for acoustic art panels.
> http://www.gikacoustics.com/gik_artpanel.html



Thnx, man. I have visited your sites-chock full of very helpful info. And VERY impressive HT build.


BTW we are geograhically close, PM sent.


----------



## hamptonht48

Hello!


Just started posting my theater build ( http://www.avsforum.com/avs-vb/showthread.php?t=1377460 ) and will finish that up (hopefully) this weekend.

However, thought this would be the better thread to post this question. Here's a pic of the back of the theater:











Front: There are bass traps behind the fabric in the corners:




















The back wall has the same slope as seen in the above pic, from above the screen to the ceiling it's about two feet. A little easier to see here.


I have corner bass traps in the front on either side of the screen, and the riser is 3/4 filled with insulation and perforated in the front to act as kind of a resonator/bass trap. I'd like to put more trapping in the back, but the wall above the DVD shelves slopes at about 45 degrees, for about two feet (hard to see in this photo). It would look kind of ugly to try a corner version of a bass trap at the top where the slope meets the flat ceiling. So my question is would it be fine to make flat panels (about 4 inch thick) and put them across the top, against the slope? I also will put, eventually, some absorption panels on the back wall in between the DVD cases. The four columns have absortion panels about two inches thick as the doors.


Note: if there is a specific link for this within the forum, I'd be very happy to have that pointed to me! I appreciate your help and thank you in advance!


H. Hampton


----------



## myfipie




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21303485
> 
> 
> sdurani, best way - I'm sure you know, is take measurements, use ETC as a tool for reflections, and take the guess work out.
> 
> 
> SoundofMind, check out GIK also for acoustic art panels.
> http://www.gikacoustics.com/gik_artpanel.html



Yes we talk about the art panel a bit in this interview I did in NYC during AES.


----------



## myfipie




> Quote:
> I have corner bass traps in the front on either side of the screen, and the riser is 3/4 filled with insulation and perforated in the front to act as kind of a resonator/bass trap. I'd like to put more trapping in the back, but the wall above the DVD shelves slopes at about 45 degrees, for about two feet (hard to see in this photo). It would look kind of ugly to try a corner version of a bass trap at the top where the slope meets the flat ceiling. So my question is would it be fine to make flat panels (about 4 inch thick) and put them across the top, against the slope? I also will put, eventually, some absorption panels on the back wall in between the DVD cases. The four columns have absortion panels about two inches thick as the doors.



It may help but not as much if it was open in the back of panel. Are the side walls in the room the same? You could think about a soffit bass trap design in that area. It will work extremely well and look natural in the room.


----------



## hamptonht48

Thanks for the reply! The side walls are actually flat, with the front and back walls having the slope. The front has somewhat of a soffit to hide the spot lights. By soffit, do you mean constructed along the back wall, where it meets the ceiling, or along the side wall towards the back? I think I can visualize what you mean, and yes, I could construct the panels so that the backs were open, except for some support bracing for attaching them. I'll Google the idea and see if I can find a pic.


Thanks again!


----------



## TMcG

Gee, I didn't realize I was going to have to have a PhD in acoustic engineering when I originally subscribed to this thread......


I am sure there are some useful nuggets of practical information in the 279 pages (so far) of this thread, but reading page after page of these most recent posts filled with hubris makes my brain go "owwy".










Can we restart this thread with some good 'ol fashioned common sense and knowledge sharing on first reflection points, absorption and diffusion placement, ideal room decay and materials, tips and tricks to help the first-time theater builder or experienced hobbyist who is looking for a few pointers from experts-at-large?


My .02 on the matter....


----------



## pepar

GK, that would seem to be a real challenge to acoustical treatment vendors ... providing effective but yet aesthetically pleasing treatments. And the corollary, providing aesthetically pleasing yet effective treatments.










Jeff


----------



## pepar




> Quote:
> Originally Posted by *TMcG* /forum/post/21313364
> 
> 
> Gee, I didn't realize I was going to have to have a PhD in acoustic engineering when I originally subscribed to this thread......
> 
> 
> I am sure there are some useful nuggets of practical information in the 279 pages (so far) of this thread, but reading page after page of these most recent posts filled with hubris makes my brain go "owwy".
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Can we restart this thread with some good 'ol fashioned common sense and knowledge sharing on first reflection points, absorption and diffusion placement, ideal room decay and materials, tips and tricks to help the first-time theater builder or experienced hobbyist who is looking for a few pointers from experts-at-large?
> 
> 
> My .02 on the matter....



Have you tried this?


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/21313414
> 
> 
> GK, that would seem to be a real challenge to acoustical treatment vendors ... providing effective but yet aesthetically pleasing treatments. And the corollary, providing aesthetically pleasing yet effective treatments.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



90% of the time the male clients say they need to check with the wife on the look. The other 10% of the time they lye about it!!











> Quote:
> Gee, I didn't realize I was going to have to have a PhD in acoustic engineering when I originally subscribed to this thread......



It really is not rocket science. You can get a very practical understanding of acoustics and get a room 90% of the way there.



> Quote:
> Thanks for the reply! The side walls are actually flat, with the front and back walls having the slope. The front has somewhat of a soffit to hide the spot lights. By soffit, do you mean constructed along the back wall, where it meets the ceiling, or along the side wall towards the back? I think I can visualize what you mean, and yes, I could construct the panels so that the backs were open, except for some support bracing for attaching them. I'll Google the idea and see if I can find a pic.



You can cover any corners. see the following.


----------



## hamptonht48

Thanks! I think I get the picture! I believe I can construct something that will fit pretty well on the top corner all the way across. I'll see what looks aesthetically pleasing, but I think I can make it square (ish) from where the corner edge of the slant meets the ceiling with about 8"-12" out from the wall. I could fill it (like a "super chunk"?) but may go with about 6 inches of material with an open back. The walls are double drywall with green glue all around, so that will help absorb what gets through. I've been in the "tweaking" phase for a while, and already love the sound in there, but hey, always room for improvement!


----------



## pepar

GK, is there any additional performance advantage to "doubling" the triangle of absorption that would be a la the SSC trap? Of is that merely the aesthetic concession?


----------



## TMcG




> Quote:
> Originally Posted by *pepar* /forum/post/21313445
> 
> 
> Have you tried this?



Pepar, have you tried private message?


Even with the search tool there are still endless results to sort through to reach the practical nuggets, so realize this before not understanding my point and making another snide comment. Thanks.


For the purposes of clarity, my point was that most thread discussions are fairly succinct and on-topic whereas this particular thread has taken on a life of it's own with much "noise" on virtually every keyword or keyphrase search. My request was that these endless limited member debates are moved to a separate discussion thread where the "Cliff Notes" on acoustical treatments could be housed here and not the "War and Peace"


----------



## pepar

All long threads "take on a life of their own." It is the nature of forums.


Good luck with your search.


----------



## TMcG

Good luck with using Private Message....which you of course won't do.


----------



## pepar

It's just not as simple as your question supposes. If you want knowledge, there is a boatload of it in this thread epitomized in posts like this . My guess is, though, that you want know-how. Well, you can commit to buying from companies like GIK and get technical support. Or you can hire pros like Dennis. If you want to be DIY, then you need to put it all together yourself ... by searching and reading.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/21313568
> 
> 
> GK, is there any additional performance advantage to "doubling" the triangle of absorption that would be a la the SSC trap? Of is that merely the aesthetic concession?



Yes, from the tests I have done, in the lab it is around a 40% improvement over all on the low end and reaches 40hz per darn well.


----------



## TMcG

That was my original point - the beginning of this thread started very focused and has now morphed into a PhD level discussion on the subtle nuances of acoustic engineering.


By way of comparison...Just because the radiator in my car may need a 50/50 mix of water in coolant put into the reservoir does not mean that I want or need to understand the subtle characteristics and impacts that radiator design and material selection has on heat transfer.


A condensed version of this thread covering the basics which would yield most of the benefit in acoustically treating a room is sufficient to most without devoting hours and days siphoning through endless posts. I wasn't saying stop this higher-level scientific discussion, but remand it to a separate sub-thread where you, Dennis and others can have an acoustic knowledge contest without cluttering the original value of this long-term thread...


----------



## pepar

Interesting approach you have there ... but here is a practical nugget .


----------



## Brad Horstkotte

There's a "your favorite acoustics posts" thread for that purpose more or less. This thread has long since jumped the shark. I still keep up on this one though because I like to watch sharks jump.


----------



## mtbdudex




> Quote:
> Originally Posted by *TMcG* /forum/post/21313364
> 
> 
> Gee, I didn't realize I was going to have to have a PhD in acoustic engineering when I originally subscribed to this thread......
> 
> 
> I am sure there are some useful nuggets of practical information in the 279 pages (so far) of this thread, but reading page after page of these most recent posts filled with hubris makes my brain go "owwy".
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Can we restart this thread with some good 'ol fashioned common sense and knowledge sharing on first reflection points, absorption and diffusion placement, ideal room decay and materials, tips and tricks to help the first-time theater builder or experienced hobbyist who is looking for a few pointers from experts-at-large?
> 
> 
> My .02 on the matter....



Actually this thread is quite tame compared to some of the Gearslutz threads.....
http://www.gearslutz.com/board/studi...ing-acoustics/ 


Since this sticky is tucked in the "Dedicated Theater Design & Construction" forum, I've tried to keep my thoughts related to more application based instead of theory based.


Theory based, I've used the "Audio theory, Setup and Chat" forum for more in depth discussions/etc.


IMO, that seems the logical way to approach.

Like Brad/others have said, this thread meanders all over the map....


Now, member jcthornton put a thread together to try and organize many of the posts and threads, it is a sticky here, " Master Thread of favorite AT links".


----------



## localhost127




> Quote:
> Originally Posted by *myfipie* /forum/post/21313957
> 
> 
> Yes, from the tests I have done, in the lab it is around a 40% improvement over all on the low end and reaches 40hz per darn well.



could you please clarify what you are comparing?


triangle-filled soffit trap vs 'square' soffit trap (both with same material)


or


soffit trap compared to your 'straddled' 4" OC703 bass traps?

if so, are the soffit traps made of OC703 or lower GFR material?


----------



## TMcG

Now, member jcthornton put a thread together to try and organize many of the posts and threads, it is a sticky here, " Master Thread of favorite AT links".[/quote]


Thanks MTBDUDEX (and jcthornton) - this is exactly what I needed.


----------



## localhost127




> Quote:
> Originally Posted by *TMcG* /forum/post/21313721
> 
> 
> Pepar, have you tried private message?
> 
> "



TMcG - sorry for the poor attitude and complete lack of help in this thread from others; i'll try and assist where necessary.


what questions did you have in mind? while there are acoustic models and particular treatment implementations that are fairly 'general', it really is best to first measure your space and identify particular issues before such treatments are selected to address. do you have the capabilities to measure your space (note that Room EQ Wizard is a free measuring software suite available for download) or are you willing to continue down that path? if not, there is still some basic methods of attack you can do. is your space home theater? 2ch listening? hybrid? single listening position or multiple rows? can you do a sketch-up of your room? ask away any questions you might have and maybe the community will be able to assist.


----------



## FOH




> Quote:
> Originally Posted by *TMcG* /forum/post/21313985
> 
> 
> That was my original point - the beginning of this thread started very focused and has now morphed into a *PhD level discussion on the subtle nuances of acoustic engineering*.



It's all good,...we'd be remiss it it weren't. As with most endeavors, at first one is entirely overwhelmed. And upon re-examination over time, layers and layers are peeled away and before you know it you're right in the thick of things.


More specifically, just pose your question(s),...even if it's theoretical, and merely in the planning stage, there are all levels of expertise here, and each bring specific skill-sets to the conversation.



> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21314204
> 
> 
> This thread has long since jumped the shark. I still keep up on this one though because I like to watch sharks jump.



+1 Me too



> Quote:
> Originally Posted by *mtbdudex* /forum/post/21314433
> 
> 
> Actually this thread is quite tame compared to some of the Gearslutz threads.....



I know that's right, things get pretty thick over there,....but it's an amazing read...good stuff




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21314433
> 
> 
> Like Brad/others have said, this thread meanders all over the map....



Yes, and we're better for it.




> Quote:
> Originally Posted by *localhost127* /forum/post/21316541
> 
> 
> what questions did you have in mind?.......
> 
> 
> ........ask away any questions you might have and maybe the community will be able to assist.



+1


What issues are you facing? What is your immediate concerns?


We all learn and sharpen our skills by revisiting best practices, and tossing around new ideas. Oftentimes, we've got to de-bunk old myths, strongly held myths that individuals pass along,...unfortunately very prevalent in audio circles.


Welcome to the thread.


----------



## myfipie




> Quote:
> Originally Posted by *localhost127* /forum/post/21314556
> 
> 
> could you please clarify what you are comparing?
> 
> 
> triangle-filled soffit trap vs 'square' soffit trap (both with same material)



Yes with the same material.


----------



## localhost127




> Quote:
> Originally Posted by *myfipie* /forum/post/21318783
> 
> 
> Yes with the same material.



OC703 or low GFR?


----------



## myfipie




> Quote:
> Originally Posted by *myfipie* /forum/post/21318783
> 
> 
> Yes with the same material.



If you are DIY'ing then I would use 3 pound or less.


BTW I got the testing back on the tuned trap with a metal membrane. Needless to say "DO NOT USE METAL"


----------



## saprano

Today i did some test with some towels and blankets on the first reflection points for the front 3 speakers. The results i found were very interesting.


While everything was definitely more clearer and less messy, the soundstage became too narrow and focused. I guess thats the point? Just hearing direct sound and no reflections. Im not sure yet if i like it. Maby i need to get use to that type of sound. It really is a weird sound and feeling. I already have a large area rug on the floor which improved things from before, having bare hardwood floors.


Will actual acoustic panels be that focused? After all im sure thick blankets and towels probably absorbed too much sound. If so, if i do get panels, im only doing the first reflection points and thats it. I wouldn't want the sound to be anymore narrow and focused than what i heard. My room is 16ft Lx11ft W

x9ft H.


Its funny cause i even read some people say that they removed their panels from the FRP because they didn't like the way it sounded. I guess this is the reason why (?). Isn't the point to _not_ tell where the sound is coming from? If i was doing 2ch music i wouldn't treat the first reflection point at all based on my findings.


----------



## nickbuol

I was going to do FPR panels, but now I am going to just focus on covering behind the speakers (front wall as I will have a false wall in front of the speakers and an AT screen), corner bass traps also hidden. I was told that (and this can be debated I am sure) that the next key location to put acoustical treatment is the back wall to prevent that large delay that can come from that major reflection point. I am at the drywall stage, so I have some time, but I will start with the "hidden" stuff first and see how far it gets me. Then experiment with the back wall next to see if it is worth it. That way the sound stage should still seem "wide" and I can always put a couple of panels up later.


----------



## myfipie




> Quote:
> Originally Posted by *saprano* /forum/post/21348592
> 
> 
> Today i did some test with some towels and blankets on the first reflection points for the front 3 speakers. The results i found were very interesting.
> 
> 
> While everything was definitely more clearer and less messy, the soundstage became too narrow and focused. I guess thats the point? Just hearing direct sound and no reflections. Im not sure yet if i like it. Maby i need to get use to that type of sound. It really is a weird sound and feeling. I already have a large area rug on the floor which improved things from before, having bare hardwood floors.
> 
> 
> Will actual acoustic panels be that focused? After all im sure thick blankets and towels probably absorbed too much sound. If so, if i do get panels, im only doing the first reflection points and thats it. I wouldn't want the sound to be anymore narrow and focused than what i heard. My room is 16ft Lx11ft W
> 
> x9ft H.
> 
> 
> Its funny cause i even read some people say that they removed their panels from the FRP because they didn't like the way it sounded. I guess this is the reason why (?). Isn't the point to _not_ tell where the sound is coming from? If i was doing 2ch music i wouldn't treat the first reflection point at all based on my findings.



There are a things you get benefit from when treating the early reflection points which over all you will get clearer imaging. Most mixes are not just hard panned (left/right) and center but spread over the area to give a full stereo image. It would be the difference of being hit with a million bee bees (at all angles) vs a huge lump of mud.









When mixing it is something that HAS to be taken care of or you will never get the mix right. If you want to know what the true mix sounds like in your room then you would have to treat also.


----------



## saprano




> Quote:
> Originally Posted by *myfipie* /forum/post/21351862
> 
> 
> There are a things you get benefit from when treating the early reflection points which over all you will get clearer imaging. Most mixes are not just hard panned (left/right) and center but spread over the area to give a full stereo image. It would be the difference of being hit with a million bee bees (at all angles) vs a huge lump of mud.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> When mixing it is something that HAS to be taken care of or you will never get the mix right. If you want to know what the true mix sounds like in your room then you would have to treat also.



I understand all that and see why its important. But does that matter if i don't like the way it sounds?







..........like pepar always says "preference over reference."


Again, maby i have to get use to it seeing how i've been listening to too much reflected sound for years. I'll add that i didn't do any EQ while doing this test. I left the EQ results i already have as is. Don't know if that matters or not.


Im not really saying it sounded bad. Just too closed in. Noticed i had to turn the volume higher also.


----------



## pauleyc




> Quote:
> Originally Posted by *saprano* /forum/post/21356614
> 
> 
> Im not really saying it sounded bad. Just too closed in. Noticed i had to turn the volume higher also.



You need a set of DSX Wides to fix it










To be honest, I recently added DSX Wides and really like them for that reason. Seems funny to spend money on treatments, and then more money to put something back







But its better after than before YMMV ...


----------



## pepar

saprano - have you tried engaging a listening mode to bring your surrounds to the party? After reading your post I watched a movie and focused on the width of the front soundstage. My surrounds are very will integrated with LCR and create a spaciousness up front and all around the room. My room is well-treated .. maybe too well, but the front soundstage is certainly not closed in.


Have you had any other HT enthusiasts in to offer their opinions?


Jeff


----------



## myfipie




> Quote:
> Originally Posted by *saprano* /forum/post/21356614
> 
> 
> I understand all that and see why its important. But does that matter if i don't like the way it sounds?
> 
> 
> 
> 
> 
> 
> 
> ..........like pepar always says "preference over reference."
> 
> 
> Again, maby i have to get use to it seeing how i've been listening to too much reflected sound for years. I'll add that i didn't do any EQ while doing this test. I left the EQ results i already have as is. Don't know if that matters or not.
> 
> 
> Im not really saying it sounded bad. Just too closed in. Noticed i had to turn the volume higher also.



Well that is why I only pointed out what it does and why someone mixing really needs to treat it. If you like it the other way and it is your room then it can't be "wrong".







Not that I would ever recommend this for a mixing or mastering room, but you might want to look at maybe diffusion in the reflection point as that might just give you the sound "YOU" want. Some time back, mind you the room was pretty large (I think around 18 feet wide), I sat in a listening room with diffusion, in the early reflection points and honestly did not hate the sound.


----------



## localhost127




> Quote:
> Originally Posted by *myfipie* /forum/post/21357331
> 
> 
> Some time back, mind you the room was pretty large (I think around 18 feet wide), I sat in a listening room with diffusion, in the *early reflection points* and honestly did not hate the sound.



with an 18ft wide room, the side-wall/lateral first reflection points are likely not early reflection points







- treatment can change accordingly if the sidewall energy is arriving outside of the haas interval.


----------



## myfipie




> Quote:
> Originally Posted by *localhost127* /forum/post/21357664
> 
> 
> with an 18ft wide room, the side-wall/lateral first reflection points are likely not early reflection points
> 
> 
> 
> 
> 
> 
> 
> - treatment can change accordingly if the sidewall energy is arriving outside of the haas interval.



lol..... I pushed send then thought "I bet you localhost127 will make some comment about the width".





















Yes I know this, my point was more to what he likes. But thanks for "JUMPING IN".









BTW I said 18ft but for all I know (I never measured it) it could have been 13 feet for all I know.


----------



## saprano




> Quote:
> Originally Posted by *pauleyc* /forum/post/21356893
> 
> 
> You need a set of DSX Wides to fix it
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> To be honest, I recently added DSX Wides and really like them for that reason. Seems funny to spend money on treatments, and then more money to put something back
> 
> 
> 
> 
> 
> 
> 
> But its better after than before YMMV ...



Im not really into the whole DSX thing. Too many speakers up front to tell you the truth.


Its pretty funny what you say though. Weird how that works



> Quote:
> Originally Posted by *pepar* /forum/post/21357121
> 
> 
> saprano - have you tried engaging a listening mode to bring your surrounds to the party? After reading your post I watched a movie and focused on the width of the front soundstage. My surrounds are very will integrated with LCR and create a spaciousness up front and all around the room. My room is well-treated .. maybe too well, but the front soundstage is certainly not closed in.
> 
> 
> Have you had any other HT enthusiasts in to offer their opinions?
> 
> 
> Jeff



Are you asking if my surrounds were on? They're always on. Surround is pretty seemless. How wide is your room? I may need to diffuse the FRP instead of absorb.


Haven't asked anyone else their opinion, but my post is there for everyone to see.



> Quote:
> Originally Posted by *myfipie* /forum/post/21357331
> 
> 
> Well that is why I only pointed out what it does and why someone mixing really needs to treat it. If you like it the other way and it is your room then it can't be "wrong".
> 
> 
> 
> 
> 
> 
> 
> Not that I would ever recommend this for a mixing or mastering room, but you might want to look at maybe diffusion in the reflection point as that might just give you the sound "YOU" want. Some time back, mind you the room was pretty large (I think around 18 feet wide), I sat in a listening room with diffusion, in the early reflection points and honestly did not hate the sound.



Yeah i was thinking diffusion might work best in my room instead of absorption. Im still going to buy some absorption panels for my room though. It just looks like i have to add diffusion to the mix too. Or leave the wall bare and focus on the front and back of the room only.


----------



## dormie1360




> Quote:
> Originally Posted by *localhost127* /forum/post/21357664
> 
> 
> with an 18ft wide room, the side-wall/lateral first reflection points are likely not early reflection points
> 
> 
> 
> 
> 
> 
> 
> - treatment can change accordingly if the sidewall energy is arriving outside of the haas interval.



Noob question. Could you explain this a little further? If you have a wide room, mines 19ft, but your main speakers are close to the side walls, (about 4 feet), due to a wide front screen, does this change the above comment. Also, googled haas interval and well........wasn't very helpful.










Thanks,

John


----------



## statonj

Is it advisable to re-run Audessey after treating primary reflection points?


Thanks


----------



## robc1976




> Quote:
> Originally Posted by *statonj* /forum/post/21371325
> 
> 
> Is it advisable to re-run Audessey after treating primary reflection points?
> 
> 
> Thanks



Yes, Without question!


----------



## nezff




> Quote:
> Originally Posted by *statonj* /forum/post/0
> 
> 
> Is it advisable to re-run Audessey after treating primary reflection points?
> 
> 
> Thanks



Yes. Of course.


----------



## localhost127




> Quote:
> Originally Posted by *dormie1360* /forum/post/21361962
> 
> 
> Noob question. Could you explain this a little further? If you have a wide room, mines 19ft, but your main speakers are close to the side walls, (about 4 feet), due to a wide front screen, does this change the above comment. Also, googled haas interval and well........wasn't very helpful.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks,
> 
> John



early-arriving, high-gain indirect signals (eg, 'early specular reflections) arriving within the haas zone where the ear-brain cannot distinguish them as separate signals, and thus 'fuses' them with the direct signal into a 'single auditory event' - will have an impact on intelligibility. if one so desires, one attenuates (eg, absorbs) such high-gain indirect signals arriving within this time-period such that the brain has ample time to digest the direct signal.


it is best to measure the acoustical behavior of the room before making decisions on what and how to 'treat'.


a tool such as the *Envelope Time Curve* (part of the free measuring suite: Room EQ Wizard) - allows one to objectionable identify *the arrival time and gain* of indirect signals vs that of the direct signal (measured one speaker at a time). from the measured response, you can determine whether such indirect energies are impeding and thus need to be treated (eg, if they are arriving within a set time-period of the direct signal (eg, 20ms) and are high enough in gain that they are above the human detection threshold). once indirect energies have been identified via the ETC response, and you make a decision that you wish to attack these indirect specular reflections - you can then apply treatment (eg absorption) and then verify that the treatment has properly attenuated the specular reflection below the human detection threshold (such that it is not processed within the ear-brain) and re-verify with another ETC measurement.


it is the actual measured acoustical behavior of the room which can assist in determining which types of treatments can be deployed to modify the room to achieve the user's design requirements (or total specular response one wishes to achieve).


here is an example of user: fotto illustrating using the ETC to trace out a spike of energy on the ETC measurement, and tracing back to identify which boundary the indirect energy is incident off of (eg, his ceiling) - and applying absorption and re-measuring with the ETC to verify the gain of the reflection has been attenuated.
http://www.avsforum.com/avs-vb/showt...1#post21248841 



some speakers (based on polar dispersion) - may not throw high-gain off-axis energy to the sidewalls. in such a case, absorption at that reflection point may not be necessary. nor, if the room was large enough, that the indirect energy was arriving outside of this zone, would absorption be necessary - and other treatment (diffusion) could be applied).


----------



## NicksHitachi

Any advice for someone experimenting with DIY acoustic diffusors?


I'm building 2'X2' panels with 5" triangles:


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21374610
> 
> 
> Any advice for someone experimenting with DIY acoustic diffusors?
> 
> 
> I'm building 2'X2' panels with 5" triangles:



AFMG Reflex is available for free 30-day trial - if you wish to model such a design to understand how it will perform before spending the time and money on building the unit.


you generally will not want a large array of repeating surfaces -


a good read:
http://www.rpginc.com/news/library/tyndall_paper.pdf


----------



## NicksHitachi




> Quote:
> Originally Posted by *localhost127* /forum/post/21374667
> 
> 
> AFMG Reflex is available for free 30-day trial - if you wish to model such a design to understand how it will perform before spending the time and money on building the unit.
> 
> 
> you generally will not want a large array of repeating surfaces -
> 
> 
> a good read:
> http://www.rpginc.com/news/library/tyndall_paper.pdf



Thanks that was informative. The author used a bunch of other peoples experimental data and wrote his/her summary of the data as applied to their hypotheses.


The paper did only mention a single incidence of sound on the diffusor and the diffusion of the prism did offer some diffusion.


I understand that this design diffusor will not be technically an absolute diffusor.


It should however perform better than bare walls currently, no?


----------



## 5150zx

Quick question, one company on-line sells either burlap fabric or microsuede covering. The microsuede looks nice, but is it as effective in absorbing as the burlap? Thanks...


----------



## dormie1360




> Quote:
> Originally Posted by *localhost127* /forum/post/21374206
> 
> 
> early-arriving, high-gain indirect signals (eg, 'early specular reflections) arriving within the haas zone where the ear-brain cannot distinguish them as separate signals, and thus 'fuses' them with the direct signal into a 'single auditory event' - will have an impact on intelligibility. if one so desires, one attenuates (eg, absorbs) such high-gain indirect signals arriving within this time-period such that the brain has ample time to digest the direct signal. ).



Thanks. So if the reflection has a much longer route from the speaker to the listener, ie a wide room, compared to the direct route from speaker to listener, "fusing" is less likely to happen. However, in my case, because my speakers are close to the wall causing the two distances to be more similar, the signals may be arriving within 20ms, and I could have a problem.


I've read the ETC posts, ( I understand some of it







) and agree this would be a beneficial measurement. I've currently gone down the OmniMic route however so as I understand it, ETC measurements are not available for me. Honestly, I have not done much with the OmniMic yet.


Also, if I understand correctly, even though reflections are arriving "much later", this can still be a problem with regards to SQ. I'm not quite sure what all the problems would be, but it sounds like these are more "peak" and "null" issues.?


Thinking all this through, I'm also realizing we are talking about one listening position. An early reflection at one seat, may not be a problem elsewhere.







Do you go with making a "perfect" seat, or try to compromise, which, just thinking about those possibilities, makes me rather glassy eyed.


I have a dedicated room that was done by someone who knew nothing about acoustics. It is my goal to improve it. The only thing I can not change are the dimensions. Thanks for your time and patience.


Regards,

John


----------



## Digital_Chris




> Quote:
> Originally Posted by *dormie1360* /forum/post/21377227
> 
> 
> Also, if I understand correctly, even though reflections are arriving "much later", this can still be a problem with regards to SQ. I'm not quite sure what all the problems would be, but it sounds like these are more "peak" and "null" issues.?



I believe that the "much later" arriving reflections will be at such a low volume that you're ears won't be able to hear them, and in turn, won't distort the direct signal. This is speaking in terms of the mid and high frequencies at least, lows I'm not sure because of the longer wavelengths.


----------



## myfipie




> Quote:
> Thinking all this through, I'm also realizing we are talking about one listening position. An early reflection at one seat, may not be a problem elsewhere. Do you go with making a "perfect" seat, or try to compromise, which, just thinking about those possibilities, makes me rather glassy eyed.



Every seat is going to have a different reflection points. Generally speaking we focus on the person paying the bill.







You can though in theory fix multiple seating spots.

I have never tested nor used one, but I have heard of people using "ramps" on the early reflection points to push the reflection past the seating spot.



> Quote:
> early-arriving, high-gain indirect signals (eg, 'early specular reflections) arriving within the haas zone where the ear-brain cannot distinguish them as separate signals, and thus 'fuses' them with the direct signal into a 'single auditory event' - will have an impact on intelligibility. if one so desires, one attenuates (eg, absorbs) such high-gain indirect signals arriving within this time-period such that the brain has ample time to digest the direct signal.
> 
> 
> it is best to measure the acoustical behavior of the room before making decisions on what and how to 'treat'.
> 
> 
> a tool such as the Envelope Time Curve (part of the free measuring suite: Room EQ Wizard) - allows one to objectionable identify the arrival time and gain of indirect signals vs that of the direct signal (measured one speaker at a time). from the measured response, you can determine whether such indirect energies are impeding and thus need to be treated (eg, if they are arriving within a set time-period of the direct signal (eg, 20ms) and are high enough in gain that they are above the human detection threshold). once indirect energies have been identified via the ETC response, and you make a decision that you wish to attack these indirect specular reflections - you can then apply treatment (eg absorption) and then verify that the treatment has properly attenuated the specular reflection below the human detection threshold (such that it is not processed within the ear-brain) and re-verify with another ETC measurement.
> 
> 
> it is the actual measured acoustical behavior of the room which can assist in determining which types of treatments can be deployed to modify the room to achieve the user's design requirements (or total specular response one wishes to achieve).
> 
> 
> here is an example of user: fotto illustrating using the ETC to trace out a spike of energy on the ETC measurement, and tracing back to identify which boundary the indirect energy is incident off of (eg, his ceiling) - and applying absorption and re-measuring with the ETC to verify the gain of the reflection has been attenuated.
> http://www.avsforum.com/avs-vb/showt...1#post21248841
> 
> 
> 
> some speakers (based on polar dispersion) - may not throw high-gain off-axis energy to the sidewalls. in such a case, absorption at that reflection point may not be necessary. nor, if the room was large enough, that the indirect energy was arriving outside of this zone, would absorption be necessary - and other treatment (diffusion) could be applied).



Very well said.


----------



## exipnos

Hi all,


Can you help me decide on the size of my superchunk corner bass traps.


I will build these out of rockwool panels RXL80 density.


RXL 80 3" (75mm) 8.0 pcf (128 kg/m3) 0.75 0.82 0.89 0.94 1.00 1.00 0.90


The thickness is actually more like 4" or 110mm but this is the closest data on

http://www.bobgolds.com/AbsorptionCoefficients.htm 


The rockwool panels where given to me for free and I have already filled my stage with the RXL80 and I have enough to do all 4 corner traps if I go for the smaller version with 24" on the front face.


I will also have soffits that are filled with rockwool batting.


Room is 4.2 m wide and 6.4 meter long with 3m ceiling.


Any advice?


----------



## myfipie




> Quote:
> Originally Posted by *exipnos* /forum/post/21382551
> 
> 
> Hi all,
> 
> 
> Can you help me decide on the size of my superchunk corner bass traps.
> 
> 
> I will build these out of rockwool panels RXL80 density.
> 
> 
> RXL 80 3" (75mm) 8.0 pcf (128 kg/m3) 0.75 0.82 0.89 0.94 1.00 1.00 0.90
> 
> 
> The thickness is actually more like 4" or 110mm but this is the closest data on
> 
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> 
> The rockwool panels where given to me for free and I have already filled my stage with the RXL80 and I have enough to do all 4 corner traps if I go for the smaller version with 24" on the front face.
> 
> 
> I will also have soffits that are filled with rockwool batting.
> 
> 
> Room is 4.2 m wide and 6.4 meter long with 3m ceiling.
> 
> 
> Any advice?



I have never tested it but with that density I don't recommend it. When you get to that thick you really want to use the less dense material. With 8 pound I would make panels 4 to 6" thick and straddle the corners. You can use less material which will let you cover more corner area. Covering more corner area is always better then less area with chunks. Keep in mind though that the minimum thickness should be 4" for the panels.


----------



## Glenn Baumann




> Quote:
> Originally Posted by *myfipie* /forum/post/21385362
> 
> 
> I have never tested it but with that density I don't recommend it. When you get to that thick you really want to use the less dense material. With 8 pound I would make panels 4 to 6" thick and straddle the corners. You can use less material which will let you cover more corner area. Covering more corner area is always better then less area with chunks. Keep in mind though that the minimum thickness should be 4" for the panels.



Glenn,


What would the performance differences be between straddling a corner with a 4" thick panel with a hollow air space behind it OR filling the entire corner with a superchunk also with a 2 foot wide face?










Does filling the whole corner with material have advantages as opposed to having a panel with a void/airspace behind it?










Thanks!



...Glenn


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21374730
> 
> 
> Thanks that was informative. The author used a bunch of other peoples experimental data and wrote his/her summary of the data as applied to their hypotheses.



the author is Cox - and along with D'antonio, probably the two most authoritative people on the subject:


absolutely required reading material if you are interested in the subject further:
http://www.amazon.com/Acoustic-Absor.../dp/0415471745 

http://books.google.com/books?id=jYB...page&q&f=false 



> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21374730
> 
> 
> The paper did only mention a single incidence of sound on the diffusor and the diffusion of the prism did offer some diffusion.



the point was to illustrate that such spatial (and especially temporal) dispersion would be extremely limited ... and the prism has two high-gain side-lobes - not something you would want in a diffuser. if many periods of the diffuser were to be used in an array (as we see quite often in order to cover large amounts of wall-space), then these problems would manifest itself further (glaring at frequencies whose spatial dispersion and angle of incidence supports such side-lobes). that's where the real issue is - not necessarily the performance of a single scatterer/diffuser, but how the array functions as a whole in the real world scenario. there are reasons why diffusers are not casually applied in massive, repeating arrays. for example wrt: applying many periods of a Schroeder diffuser, one will take advantage of modulation via the Inverse panel and design the array layout with regards to the Barker Code ( http://en.wikipedia.org/wiki/Barker_code ) to achieve even dispersion and limit lobing:



http://imgur.com/CgjKT.png%5B/IMG%5D




http://imgur.com/wSDXM.png%5B/IMG%5D




http://imgur.com/bT2rr.png%5B/IMG%5D




http://imgur.com/u1Z1J.png%5B/IMG%5D




this is generally why with PRDs, it is better to design a single, large (single order/higher prime N) diffuser vs using multiple copies of a lower-order N diffuser (repeating periods to cover the same surface area). limit lobing and increase the complexity of the returned diffuse-field.


QRDude ( http://www.subwoofer-builder.com/qrdude.htm ) is absolutely wonderfully-written application for Schroeder Quadratic Residue Diffusers. even if you're not building QRDs, the technical guide is a very worthwhile read:
http://www.subwoofer-builder.com/qrdude.htm 


QRDude supports Inverse Panels, so you can play around with it (visually!) to get a better understanding of the significance - and why modulation is important for using large amounts of repeating diffusers.


the prism diffuser in your example photo above may produce unintended results with such high amounts of repeating surfaces - you may get glaring or high-gain side-lobes at some frequencies (and angle of incidences) than others - which could easily make the room sound much worse.




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21374730
> 
> 
> It should however perform better than bare walls currently, no?



depends on the behavior of the array of diffusers as a whole -


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Glenn Baumann* /forum/post/21385441
> 
> 
> Glenn,
> 
> 
> What would the performance differences be between straddling a corner with a 4" thick panel with a hollow air space behind it OR filling the entire corner with a superchunk also with a 2 foot wide face?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Does filling the whole corner with material have advantages as opposed to having a panel with a void/airspace behind it?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks!
> 
> 
> 
> ...Glenn


 http://forum.studiotips.com/viewtopi...perchunks+test 


yes


----------



## localhost127




> Quote:
> Originally Posted by *dormie1360* /forum/post/21377227
> 
> 
> Thanks. So if the reflection has a much longer route from the speaker to the listener, ie a wide room, compared to the direct route from speaker to listener, "fusing" is less likely to happen. However, in my case, because my speakers are close to the wall causing the two distances to be more similar, the signals may be arriving within 20ms, and I could have a problem.
> 
> 
> I've read the ETC posts, ( I understand some of it
> 
> 
> 
> 
> 
> 
> 
> ) and agree this would be a beneficial measurement. I've currently gone down the OmniMic route however so as I understand it, ETC measurements are not available for me. Honestly, I have not done much with the OmniMic yet.
> 
> 
> Also, if I understand correctly, even though reflections are arriving "much later", this can still be a problem with regards to SQ. I'm not quite sure what all the problems would be, but it sounds like these are more "peak" and "null" issues.?
> 
> 
> Thinking all this through, I'm also realizing we are talking about one listening position. An early reflection at one seat, may not be a problem elsewhere.
> 
> 
> 
> 
> 
> 
> 
> Do you go with making a "perfect" seat, or try to compromise, which, just thinking about those possibilities, makes me rather glassy eyed.
> 
> 
> I have a dedicated room that was done by someone who knew nothing about acoustics. It is my goal to improve it. The only thing I can not change are the dimensions. Thanks for your time and patience.
> 
> 
> Regards,
> 
> John



John,

if you're willing to give the topic some attention, a good head-start would be mas' commentary in this thread:

http://www.hometheatershack.com/foru...tml#post305617 


enjoy


----------



## dormie1360




> Quote:
> Originally Posted by *localhost127* /forum/post/21391816
> 
> 
> John,
> 
> if you're willing to give the topic some attention, a good head-start would be mas' commentary in this thread:
> 
> http://www.hometheatershack.com/foru...tml#post305617
> 
> 
> enjoy



Absolutely! Will check it out....thanks.


----------



## NicksHitachi

I started some DIY diffusers today.


They are 45/90/45 triangles. 7" wide at base and 3.25" tall. Each of these panels are approx. 2'x2'. The triangles are 3/16" tempered hardboard.


Now before i get admonished for creating something which is not a perfect diffuser, i am aware they are not PERFECT. They are however better than my bare walls and seeing as the room is a dedicated theater absorption is the only other thing going on the walls.


Im also going to build some panels which are larger with longer diffusor panels to alternate with the absorpion.


Im thinking about stuffing the voids under the triangles with polyfill or fiberglass, is this a good idea?


----------



## myfipie




> Quote:
> Originally Posted by *Glenn Baumann* /forum/post/21385441
> 
> 
> Glenn,
> 
> 
> What would the performance differences be between straddling a corner with a 4" thick panel with a hollow air space behind it OR filling the entire corner with a superchunk also with a 2 foot wide face?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Does filling the whole corner with material have advantages as opposed to having a panel with a void/airspace behind it?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks!
> 
> 
> 
> ...Glenn



With all the testing I have done over the years I have found that with a panel (higher density) that is 4" to 6" you get a nice boost in absorption around 80 hz due to spring action (the panel itself is moving), but it starts to fall off pretty quick at that point. With a filled area the boost is not as large but it will go much lower in absorption. If you look at our testing of the 244, Monster Trap, Tri Trap and Soffit Trap you can see what I am talking about. FYI though I can't say for sure that if you build it yourself you would have the same results.


----------



## myfipie




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21394702
> 
> 
> I started some DIY diffusers today.
> 
> 
> They are 45/90/45 triangles. 7" wide at base and 3.25" tall. Each of these panels are approx. 2'x2'. The triangles are 3/16" tempered hardboard.
> 
> 
> Now before i get admonished for creating something which is not a perfect diffuser, i am aware they are not PERFECT. They are however better than my bare walls and seeing as the room is a dedicated theater absorption is the only other thing going on the walls.
> 
> 
> Im also going to build some panels which are larger with longer diffusor panels to alternate with the absorpion.
> 
> 
> Im thinking about stuffing the voids under the triangles with polyfill or fiberglass, is this a good idea?



I am sure it is better then a bare wall, but a bookshelf is better then a bare wall also.







There is just no way to say what those will or will not do, so I would recommend against it. The point of acoustics, IMO is that you use things that you can predict.


----------



## exipnos




> Quote:
> Originally Posted by *myfipie* /forum/post/21402452
> 
> 
> With all the testing I have done over the years I have found that with a panel (higher density) that is 4" to 6" you get a nice boost in absorption around 80 hz due to spring action (the panel itself is moving), but it starts to fall off pretty quick at that point. With a filled area the boost is not as large but it will go much lower in absorption. If you look at our testing of the 244, Monster Trap, Tri Trap and Soffit Trap you can see what I am talking about. FYI though I can't say for sure that if you build it yourself you would have the same results.



Would it then make sense to straddle the corner with the 4" panel and loosely fill the back with lesser density rockwool? I have the material so its not like I have to purchase anything.


----------



## pepar

Glenn's post indicates the tradeoffs ... you're thinking "best of both worlds?"


I can tell you that unless you are in the field of acoustics, many things that "make sense" don't actually happen the way you'd think.


----------



## robc1976




> Quote:
> Originally Posted by *myfipie* /forum/post/21402452
> 
> 
> With all the testing I have done over the years I have found that with a panel (higher density) that is 4" to 6" you get a nice boost in absorption around 80 hz due to spring action (the panel itself is moving), but it starts to fall off pretty quick at that point. With a filled area the boost is not as large but it will go much lower in absorption. If you look at our testing of the 244, Monster Trap, Tri Trap and Soffit Trap you can see what I am talking about. FYI though I can't say for sure that if you build it yourself you would have the same results.



I can say one thing for sure.....your Tri-traps are amazing...I have all the corners in my rpoom filled with them as well as 3 monster traps on the back wall...HUGE difference! Well worth the $$$$ I still need to post and email you pics!


----------



## myfipie




> Quote:
> Originally Posted by *exipnos* /forum/post/21403954
> 
> 
> Would it then make sense to straddle the corner with the 4" panel and loosely fill the back with lesser density rockwool? I have the material so its not like I have to purchase anything.



Honestly filling the corner with one density is a proven method so I recommend not fixing what is not broken. There are just to many unknown factors that could or couldn't help.



> Quote:
> I can say one thing for sure.....your Tri-traps are amazing...I have all the corners in my rpoom filled with them as well as 3 monster traps on the back wall...HUGE difference! Well worth the $$$$ I still need to post and email you pics!



Thank you!! And yes please send me pictures when you get a moment.


----------



## exipnos




> Quote:
> Originally Posted by *myfipie* /forum/post/21407166
> 
> 
> Honestly filling the corner with one density is a proven method so I recommend not fixing what is not broken. There are just to many unknown factors that could or couldn't help.
> 
> 
> 
> 
> Thank you!! And yes please send me pictures when you get a moment.



just trying to understand whats going on. The advice on studio tips is that you can indeed stuff the back side with extra insulation to get slightly better performance.

http://forum.studiotips.com/viewtopic.php?f=8&t=534 


Does this not apply here because I'm using higher density rock wool? On two of my back corners I have a ventilation tube (flexible plastic version) and I thought it would help making it immobile so that it does not move.


----------



## myfipie




> Quote:
> Originally Posted by *exipnos* /forum/post/21407411
> 
> 
> just trying to understand whats going on. The advice on studio tips is that you can indeed stuff the back side with extra insulation to get slightly better performance.
> 
> http://forum.studiotips.com/viewtopic.php?f=8&t=534
> 
> 
> Does this not apply here because I'm using higher density rock wool? On two of my back corners I have a ventilation tube (flexible plastic version) and I thought it would help making it immobile so that it does not move.



I was going to write this in my last post but did not as I figured it would confuse more then actually help, but if you did want to put absorption behind the panel I would not let it touch the front panel. I really don't think you would get all that much better results after testing though.


----------



## aaron3421




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21389337
> 
> http://forum.studiotips.com/viewtopi...perchunks+test
> 
> 
> yes



The link you posted does not appear to support your statement as poster inquired about equal width facing.


----------



## pinstripes

Any idea where to find Guilford of Maine Cape Cod fabric?

I sent an email to fabricmate and they have not responded.

GOM said they would sell it to me directly but I was hoping to find it cheaper through a retailer.


----------



## nezff




> Quote:
> Originally Posted by *pinstripes* /forum/post/21447003
> 
> 
> Any idea where to find Guilford of Maine Cape Cod fabric?
> 
> I sent an email to fabricmate and they have not responded.
> 
> GOM said they would sell it to me directly but I was hoping to find it cheaper through a retailer.



might try acoustimac, ask for Sal. He might be able to help you.


----------



## sukumar

The following link shows up to 4000hz. What happens after this ? Whatever coefficeint at 4000hz applies to 4khz to 20khz?

http://www.bobgolds.com/AbsorptionCoefficients.htm 


Another question is bothering me;-) Why bass lives in corners of the room? I read that bass traps are needed in every corner of the room.


----------



## FOH




> Quote:
> Originally Posted by *sukumar* /forum/post/21453410
> 
> 
> Another question is bothering me;-) Why bass lives in corners of the room? I read that bass traps are needed in every corner of the room.



Think velocity, and and pressure.


As the bass waves approach a boundary, both the velocity and pressure become reset when they encounter the boundary.


So the bass wave possesses a maximum velocity 1/4 wavelength from the wall (picture a sine wave). At half the wavelength, the velocity is minimum, then maximum again at the 3/4 point.


At the wall, pressure is maximum, at the 1/4 points, velocity is maximum.



So, to answer your question, at any boundary the wave resets, turns back. Some energy is lost due to pressure forces moving the wall, the remainder of the energy doubles back and it can be absorbed by fiberglass etc., most effective at the 1/4 wavelength points. So the corners are intersections of multiple boundaries, so the waves tend to double back and occur all together near the corners.











The above is a great graphic from Ethan Winer's superb paper that explains all this much better than I could ever do.


Additionally, here is Toole's solid paper of bass waves in a listening room.


Those two documents, are the two best acoustics, and bass in small room documents I can think of that will serve you the best.



Good luck


----------



## EBinMD

I've read through most of the pages here and have a few more questions that I don't think have been asked before.


I understand that we should use bass traps in corners, or where a wall meets a wall, floor meets wall, and ceiling meets wall. But what about when you have a bulkhead that runs the length of the room? Does that create another spot that needs to be treated?


Also, I have read about the need for diffusion or reflection on the back wall. If you have 2 rows of chairs, with the second on a platform, is there still a need if the backrow of chairs essentially blocks the front speakers from the back wall?


I built a set of corner chunks (floor to ceiling) for the front wall, but surprisingly I didn't notice much of a difference. Is that normal?


----------



## sukumar




> Quote:
> Originally Posted by *FOH* /forum/post/21455613
> 
> 
> Think velocity, and and pressure.
> 
> 
> As the bass waves approach a boundary, both the velocity and pressure become reset when they encounter the boundary.
> 
> 
> So the bass wave possesses a maximum velocity 1/4 wavelength from the wall (picture a sine wave). At half the wavelength, the velocity is minimum, then maximum again at the 3/4 point.
> 
> 
> At the wall, pressure is maximum, at the 1/4 points, velocity is maximum.
> 
> 
> 
> So, to answer your question, at any boundary the wave resets, turns back. Some energy is lost due to pressure forces moving the wall, the remainder of the energy doubles back and it can be absorbed by fiberglass etc., most effective at the 1/4 wavelength points. So the corners are intersections of multiple boundaries, so the waves tend to double back and occur all together near the corners.
> 
> 
> The above is a great graphic from Ethan Winer's superb paper that explains all this much better than I could ever do.
> 
> 
> Additionally, here is Toole's solid paper of bass waves in a listening room.
> 
> 
> Those two documents, are the two best acoustics, and bass in small room documents I can think of that will serve you the best.
> 
> 
> 
> Good luck



Thanks a lot for taking time to post detailed reply with illustration. That makes sense. I will read two links.


----------



## greentea

Hi all,

I read through some of the basic here and I am handy so I did my panels with 2" Owens Corning insulation. Can some of the experts take a look of these pictures that I posted from the other forum to see if I am ok with sound treatment from my room?


http://www.avsforum.com/avs-vb/showt...3#post21458653


----------



## FOH




> Quote:
> Originally Posted by *EBinMD* /forum/post/21456559
> 
> 
> I understand that we should use bass traps in corners, or where a wall meets a wall, floor meets wall, and ceiling meets wall. But what about when you have a bulkhead that runs the length of the room? Does that create another spot that needs to be treated?



Yes, if needed. Here's a product that's made for just an application. Also, one can certainly entertain a DIY approach as well.




> Quote:
> Originally Posted by *EBinMD* /forum/post/21456559
> 
> 
> Also, I have read about the need for diffusion or reflection on the back wall. If you have 2 rows of chairs, with the second on a platform, is there still a need if the backrow of chairs essentially blocks the front speakers from the back wall?



You can't merely think in terms of direct energy, as there's significant reflected energy too.




> Quote:
> Originally Posted by *EBinMD* /forum/post/21456559
> 
> 
> I built a set of corner chunks (floor to ceiling) for the front wall, but surprisingly I didn't notice much of a difference. Is that normal?



So, so many variables. Bass traps can help mitigate frequency response issues to some degree, when properly built/implemented, they can be quite effective to damp ringing. Do you have the capacity to measure in the time domain? If properly designed/built/installed, bass traps are _almost_ a not miss proposition.




Good luck


----------



## pepar




> Quote:
> Originally Posted by *EBinMD* /forum/post/21456559
> 
> 
> I understand that we should use bass traps in corners, or where a wall meets a wall, floor meets wall, and ceiling meets wall. But what about when you have a bulkhead that runs the length of the room? Does that create another spot that needs to be treated?





> Quote:
> Originally Posted by *FOH* /forum/post/21459948
> 
> 
> Yes, if needed. Here's a product that's made for just an application.



He *has* a bulkhead and is asking if the "corners" where it meets the ceiling and walls is somewhere that should be trapped.


I'd say yes.


Plus I'd investigate if the bulkhead could be modified to accept some fiberglass, and if so, can is be covered with acoustically transparent cloth instead of drywall.


----------



## FOH




> Quote:
> Originally Posted by *greentea* /forum/post/21458942
> 
> 
> Hi all,
> 
> I read through some of the basic here and I am handy so I did my panels with 2" Owens Corning insulation. Can some of the experts take a look of these pictures that I posted from the other forum to see if I am ok with sound treatment from my room?
> 
> 
> http://www.avsforum.com/avs-vb/showt...3#post21458653



Too difficult to determine from pics,..you really need to measure your room if you want to pursue acoustics with any accuracy,...as without you're merely shooting in the dark.


Consider SBIR, and the environment immediately surrounding the mains (to the rear and sides). Be mindful of VER (very early reflections) form diffraction to image smearing items in the vicinity of the mains. Then you want to examine sidewall, ceiling and floor reflections that are significant enough that they negatively impact the LP. Bass traps to possibly smooth response and damp in the time domain. Any large blank and flat wall areas may need some diffusion, scattering, and just be mindful not to over absorb in the MF/HF range.

Read this superb post,...yes it's heavy, however it contains some absolute gold wrt small room acoustics.

Here's another.


Nyal, from Acoustic Frontiers , has some goodies on his site.


Also, Paul Spencer from Red Spade Audio also has some great stuff on his site regarding SBIR, bass integration, etc.


All the above are frequent AVS contributors, do the homework and take this as far as you want. It's not about equipment, it's about good acoustic interaction of your system and room. Huge, huge gains to be had with modest amounts of optimization.



Good luck


----------



## FOH




> Quote:
> Originally Posted by *pepar* /forum/post/21459991
> 
> 
> He *has* a bulkhead and is asking if the "corners" where it meets the ceiling and walls is somewhere that should be trapped.
> 
> 
> I'd say yes.
> 
> 
> Plus I'd investigate if the bulkhead could be modified to accept some fiberglass, and if so, can is be covered with acoustically transparent cloth instead of drywall.



Yep,...missed that


Again,..._if needed_


Thanks Pepar



btw, many builds illustrate such an application


----------



## pepar




> Quote:
> Originally Posted by *FOH* /forum/post/21460019
> 
> 
> Read this superb post,...yes it's heavy, however it contains some absolute gold wrt small room acoustics.
> 
> Here's another.



Thanks. Bookmarked.



> Quote:
> All the above are frequent AVS contributors, do the homework and take this as far as you want. It's not about equipment, it's about good acoustic interaction of your system and room. *Huge, huge gains to be had with modest amounts of optimization*.



Truer words were never spoken. I did not bolden it, but the homework part is important as well.


Jeff


----------



## EBinMD

Thanks for the response. I have attached some pictures of my room. I haven't been entirely happy with the acoustics when listening to music, so I'm trying to figure out what I can do. I had some pretty bad slap echo in the front half of the room. Once I added the side panels it helped, and then added the superchunk traps and that also helped some more, but there is still some there.


I use the room for about 60% movies, 40% music. I sit in the front middle row when listening to music and is really the only seat I care about. In general, movies sound good no matter which seat (and most people aren't as critical as I am), however there is more bass in the back rows (probably expected because they are close to the back wall).


I'm wondering if I should try to tame reflections off the ceiling bulkhead (I determined that's a reflection point from the mirror test) or use some bass traps at the bulkhead or back corners of the room.


----------



## pepar

Ahh, the bulkhead runs the length of the room ... down the middle. As far as corner traps go, those areas are not obstructed by the bulkhead. I had mistakenly read your original post as the bulkhead was around perimeter. You could probably safely add more SSC traps before needing to do measurements. And, _if needed_, the product linked by FOH could be used around the ceiling/wall corners.


I would put an absorber on the ceiling at the first reflection point ... where ever that happens to fall.


----------



## greentea




> Quote:
> Originally Posted by *FOH* /forum/post/21460019
> 
> 
> Too difficult to determine from pics,..you really need to measure your room if you want to pursue acoustics with any accuracy,...as without you're merely shooting in the dark.
> 
> 
> Consider SBIR, and the environment immediately surrounding the mains (to the rear and sides). Be mindful of VER (very early reflections) form diffraction to image smearing items in the vicinity of the mains. Then you want to examine sidewall, ceiling and floor reflections that are significant enough that they negatively impact the LP. Bass traps to possibly smooth response and damp in the time domain. Any large blank and flat wall areas may need some diffusion, scattering, and just be mindful not to over absorb in the MF/HF range.
> 
> Read this superb post,...yes it's heavy, however it contains some absolute gold wrt small room acoustics.
> 
> Here's another.
> 
> 
> Nyal, from Acoustic Frontiers , has some goodies on his site.
> 
> 
> Also, Paul Spencer from Red Spade Audio also has some great stuff on his site regarding SBIR, bass integration, etc.
> 
> 
> All the above are frequent AVS contributors, do the homework and take this as far as you want. It's not about equipment, it's about good acoustic interaction of your system and room. Huge, huge gains to be had with modest amounts of optimization.
> 
> 
> 
> Good luck



Many thanks!!


----------



## Mongao

Hi all,


Please, I am looking for information about acoustic panel dealers in Canada.


I am looking for something like this:

http://www.atsacoustics.com/panels 


But this one is based in USA, and I need to find something similar in Canada, I am in Montreal.


I am VERY NEW to this "treatment stuff", I have noticed that there`s some reverberation (echo) in my basement (5.7 x 4.5 meters), so I am willing to try to improve it but not spending more than 1000 CAD.


Suggestions please ?


Thanks a lot,


Mongao


----------



## myfipie




> Quote:
> Originally Posted by *Mongao* /forum/post/21462364
> 
> 
> Hi all,
> 
> 
> Please, I am looking for information about acoustic panel dealers in Canada.
> 
> 
> I am looking for something like this:
> 
> http://www.atsacoustics.com/panels
> 
> 
> But this one is based in USA, and I need to find something similar in Canada, I am in Montreal.
> 
> 
> I am VERY NEW to this "treatment stuff", I have noticed that there`s some reverberation (echo) in my basement (5.7 x 4.5 meters), so I am willing to try to improve it but not spending more than 1000 CAD.
> 
> 
> Suggestions please ?
> 
> 
> Thanks a lot,
> 
> 
> Mongao



Those panels can be used for general high end decay, but what you really want is to start off with some bass trapping. Low end is the killer in a smaller room. See the following for more info.
http://www.gikacoustics.com/education.html 
http://www.gikacoustics.com/news_081610.html 
http://www.gikacoustics.com/room_setup.php 


Also the following video (sorry English subtitles) gives you a great before and after testing and starting around 3:30 in the video has music playing with and without treatment. It lets you hear the difference.








http://www.gikacoustics.com/treated_video.html 



Glenn Kuras


----------



## Mongao




> Quote:
> Originally Posted by *myfipie* /forum/post/21463887
> 
> 
> Those panels can be used for general high end decay, but what you really want is to start off with some bass trapping. Low end is the killer in a smaller room. See the following for more info.
> http://www.gikacoustics.com/education.html
> http://www.gikacoustics.com/news_081610.html
> http://www.gikacoustics.com/room_setup.php
> 
> 
> Also the following video (sorry English subtitles) gives you a great before and after testing and starting around 3:30 in the video has music playing with and without treatment. It lets you hear the difference.
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.gikacoustics.com/treated_video.html
> 
> 
> 
> Glenn Kuras



Thanks Glen, I'll take a look.


Mongao


----------



## dragonleepenn




> Quote:
> Originally Posted by *EBinMD* /forum/post/21460677
> 
> 
> Thanks for the response. I have attached some pictures of my room. I haven't been entirely happy with the acoustics when listening to music, so I'm trying to figure out what I can do. I had some pretty bad slap echo in the front half of the room. Once I added the side panels it helped, and then added the superchunk traps and that also helped some more, but there is still some there.
> 
> 
> I use the room for about 60% movies, 40% music. I sit in the front middle row when listening to music and is really the only seat I care about. In general, movies sound good no matter which seat (and most people aren't as critical as I am), however there is more bass in the back rows (probably expected because they are close to the back wall).
> 
> 
> I'm wondering if I should try to tame reflections off the ceiling bulkhead (I determined that's a reflection point from the mirror test) or use some bass traps at the bulkhead or back corners of the room.



You should trap at the bulk head, i have the same bulk head, i use the foam style(for convience) corner wedge traps accross the bulk head. It does work fine, however you can build a soffit in front of the bulk head and fill it with insulation making it a bass trap. You have a cool room, noticed the side wall treatment, i would raise them up mid-way . Is your front wall treated? If not it would help the sound to have it done. You can do a false wall two inches in front, get some ultra touch or roxul or some other material and put it between the false wall studs, either 16"or 24" on center. I bet you will like the improvement. Looks like you need rear treatment and some rear subs, that will also make a big difference in over all sound.


----------



## TrueBeliever

Hi all.


Thanks for all the information here. Very valuable.


I am considering to do some acoustic treatment because my room sucks (20' x 14.4' x 8,2').


Here is what my front speakers measured withou eq and subwoofers against front speakers with subs and audyssey on my main listening position:
http://img846.imageshack.us/img846/8871/grafico3u.jpg 



Unfortunately, I can´t change my main listening position wich is about 6 feet from rear wall.


But, fortunately, I can do some acoustic treatment.


I think I will start with two superchunks(24" front) at the front of the room using 2pcf rockwool and then add kraft paper facing the room.


Then, if it works well, I will add two rear soffit corner traps floor to ceiling (24"wide and 12"deep) made of the same 2pcf rockwool with kraft paper facing the room.


What do you think ?


----------



## Hvacins

Hey guys...


I've been burning the midnight oil researching acoustic paneling. I've narrowed down to Owens Corning 705 2" panels doubled up into a 4" frame. I'm going to build a bunch from scratch and place in all locations as possible. However I am having a hell of a time finding a local supplier.

So far I could only find the Knauf Black face acoustical panels with ECOSE treatment... As that local supplier said it was the 2" OC703 3lb pcf equivelant. A case of (6) 2" panels for about $120 pre tax.

I'd rather go with the 705 panels if possible... Is there anybody here from the Orange County California that knows of a local place to shop at?... Worst case I could always order online... But shipping approx 6 cases would kill my local tax bracket.


----------



## pepar

This stuff used in the HVAC industry and is most reasonably priced when purchased through "insulation" suppliers. Many of us buy from Specialty Products & Insulation , but they do not have local distribution in your state. Still, they certainly *have* HVAC in CA, so there are companies similar to SPI. Try googling "fiberglass" "HVAC" "California".


edit: ' ere ya go .


Jeff


----------



## mtbdudex




> Quote:
> Originally Posted by *Hvacins* /forum/post/0
> 
> 
> Hey guys...
> 
> 
> I've been burning the midnight oil researching acoustic paneling. I've narrowed down to Owens Corning 705 2" panels doubled up into a 4" frame. I'm going to build a bunch from scratch and place in all locations as possible. However I am having a hell of a time finding a local supplier.
> 
> So far I could only find the Knauf Black face acoustical panels with ECOSE treatment... As that local supplier said it was the 2" OC703 3lb pcf equivelant. A case of (6) 2" panels for about $120 pre tax.
> 
> I'd rather go with the 705 panels if possible... Is there anybody here from the Orange County California that knows of a local place to shop at?... Worst case I could always order online... But shipping approx 6 cases would kill my local tax bracket.



What is your Goal here?

Broadband bass trapping, establish a RFZ, or?


Knowing your goal, etc will help people give you support.

Also helps with a room layout picture.


----------



## Hvacins

I'll try my best to make up some sort of room layout... Lol this will be interesting in itself cause I suck a drawing... I have a wicked cramped 11'W x 12'L 8'-9'H shoebox of a dedicated HT room. The room has 2 types of vaulted ceilings... Front half single slope, back half 2 slopes with high point down the middle, and a few soffits to boot... Confusing I know. I'll work on pics and drawings to help explain...

Overall goal is to tame my room acoustics... Diffuse, absorb, and clean up ... I'm fairly new to all this so I have no clue what GREAT sounds like, but I know my room sounds like Mariachi music blasting from a tin can!!!! And I don't care for that at all...


My speaker placements are far from ideal... Angles are all wrong... But I'm stuck with where everything is located so I have to make do with what I have already in place... Moving furniture, speakers, and equipment is not an option. Therefore treatments to tame the beast is next. I am renting this house and have just over 4 years left on my lease, so I'll be here a while but will need to remove when I go.


I'll post up the initial layout and all advice is greatly appreciated...


Thanks pepar for the advice... I've seen you around on many different threads and always look forward to your advice.


----------



## mtbdudex

Will you take acoustic measurements?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *TrueBeliever* /forum/post/21470711
> 
> 
> What do you think ?



Sounds like a good start - make sure to capture a waterfall too, which will help you tell what impact you've had before and after on any modal ringing issues (particular frequencies that are decaying slowly).


----------



## localhost127




> Quote:
> Originally Posted by *TrueBeliever* /forum/post/21470711
> 
> 
> Unfortunately, I can´t change my main listening position wich is about 6 feet from rear wall.



much better than being stuck sitting against the rear wall -



> Quote:
> Originally Posted by *TrueBeliever* /forum/post/21470711
> 
> 
> I think I will start with two superchunks(24" front) at the front of the room using 2pcf rockwool and then add kraft paper facing the room.



can you fit 34" faced or larger? if so, you can use pink fluffy attic insulation (loosely filled!). just mind that if you are stacking vertically, you'll want to add horizontal supports every few ft such that the upper layers do not compress the lower layers. +1 for applying a reflective face such that you reflect some mid-high specular energy back into the room to restrict the LF absorbers from over-absorbing specular energy and creating a damped room. you can also use plastic covering on the outside face (no thinner than 6mil).


----------



## Hvacins

I know I'm going about this all wrong... I was planning on doing the room treatments by ear and mirror... Lol. I wouldn't have the first clue on taking measurements, let alone decipher their cryptic message. Heck... I still haven't got a clue if I even did the MCAAC and Svs aseq1 properly. Ohhh does my head hurt.... We all had to start somewhere, cant learn it overnight.


And no... I don't have a waterfall in my room!!!! Just kidding... I have no clue what waterfall means nor how to effectively read one.


For the time being, I'm shooting to get a better experience in the short term... Surely adding some treatment will greatly help. As long as I don't over do it and make my space overly dead. I'm humble in my ways... Once I fully understand how all these pieces of the puzzle fit together... Then I'll go for perfection. Until then I'd just like it to sound good...


----------



## Hvacins

Btw... What's the easiest way for me to layout my room? Old fashion pen n paper hand sketched scanned in and downloaded... Or is there some easy to use computer program to draw it up? If computer based rendered... What program would I use and where to find? I'll try to get some pictures but really need a panoramic lens as its a small room...


Thanks...


----------



## localhost127




> Quote:
> Originally Posted by *Hvacins* /forum/post/21474434
> 
> 
> Btw... What's the easiest way for me to layout my room? Old fashion pen n paper hand sketched scanned in and downloaded... Or is there some easy to use computer program to draw it up? If computer based rendered... What program would I use and where to find? I'll try to get some pictures but really need a panoramic lens as its a small room...
> 
> 
> Thanks...



google sketchup


----------



## myfipie




> Quote:
> Originally Posted by *Hvacins* /forum/post/21473347
> 
> 
> I know I'm going about this all wrong... I was planning on doing the room treatments by ear and mirror... Lol. I wouldn't have the first clue on taking measurements, let alone decipher their cryptic message. Heck... I still haven't got a clue if I even did the MCAAC and Svs aseq1 properly. Ohhh does my head hurt.... We all had to start somewhere, cant learn it overnight.
> 
> 
> And no... I don't have a waterfall in my room!!!! Just kidding... I have no clue what waterfall means nor how to effectively read one.
> 
> 
> For the time being, I'm shooting to get a better experience in the short term... Surely adding some treatment will greatly help. As long as I don't over do it and make my space overly dead. I'm humble in my ways... Once I fully understand how all these pieces of the puzzle fit together... Then I'll go for perfection. Until then I'd just like it to sound good...



Most people do not know how to shot the room and once they do learn, they really don't understand the data. Don't feel bad, just get a good amount of bass trapping in the room and cover the early reflection points. The other option is to work with a company that can do the layout for you.


----------



## myfipie




> Quote:
> Originally Posted by *Hvacins* /forum/post/21474434
> 
> 
> Btw... What's the easiest way for me to layout my room? Old fashion pen n paper hand sketched scanned in and downloaded... Or is there some easy to use computer program to draw it up? If computer based rendered... What program would I use and where to find? I'll try to get some pictures but really need a panoramic lens as its a small room...
> 
> 
> Thanks...



You can also just take a bunch of pictures and let us know the dimensions of the room.


----------



## mtbdudex




> Quote:
> Originally Posted by *Hvacins* /forum/post/21474434
> 
> 
> Btw... What's the easiest way for me to layout my room? Old fashion pen n paper hand sketched scanned in and downloaded... Or is there some easy to use computer program to draw it up? If computer based rendered... What program would I use and where to find? I'll try to get some pictures but really need a panoramic lens as its a small room...
> 
> 
> Thanks...





> Quote:
> Originally Posted by *localhost127* /forum/post/21475227
> 
> 
> google sketchup



Whatever workd for you to accurately show the physical location of your listening space.

google sketchup is the best, but a learning curve.

For me, I used simply hand drawn on top of construction blueprint, scanned, then added info via simple MS Paint.

If you have grid paper you could quickly do same, then possible transfer it via scanning, then manipulate in the digital.


As Glenn stated, pictures do work, but then we miss the correctly scaled plan view which really helps quickly grasp things.


having in google sketch up gives you/others ability to see 3D iso view, that is best, depends on your ability to learn it.


----------



## TrueBeliever




> Quote:
> Originally Posted by *localhost127* /forum/post/21473188
> 
> 
> much better than being stuck sitting against the rear wall -
> 
> 
> 
> 
> can you fit 34" faced or larger? if so, you can use pink fluffy attic insulation (loosely filled!). just mind that if you are stacking vertically, you'll want to add horizontal supports every few ft such that the upper layers do not compress the lower layers. +1 for applying a reflective face such that you reflect some mid-high specular energy back into the room to restrict the LF absorbers from over-absorbing specular energy and creating a damped room. you can also use plastic covering on the outside face (no thinner than 6mil).



34" faced or larger is not possible, only if I make it asymmetric. But, I can fit a soffit corner trap bigger at the front of the room even though superchuncks seem to integrate better to the ambient.


My only concern is that I can´t find pink fluffy here ( Brazil). But the specs of that rockwool that I can easily find is similar of the Roxul AFB. And its price is fair.


----------



## Hvacins

Thanks for all your guidance... I'll try google sketch and the other methods if needed. I'll work this up in the next few days and hopefully have it submitted by Monday.... ( need to use my stealth ninja skills, My Wife hates the time and money spent on my man cave ) I really look forward to all your inputs and thoughts. This is a great community to be a part of and I'd like to pat each of you on the back for taking the time to help out us new guys.


----------



## sukumar

I am planning to measure my room acoustics. I read that ETC is needed. I installed Room Eq wizard and still trying to understand.


I guess I need following based on my understanding from the forum


1. calibrated micro phone

2. Pre amp or sound card. Not sure which one I need.


I am going to use my laptop.


I read to buy x32 pre amp. I don't mind spending little more. Could you please share good model that works for you. I don't have clue what is this pre amp.


Do I need External sound card also?


Please recommend good microphone also.

Thanks for your time.


----------



## Edwoo




> Quote:
> Originally Posted by *Hvacins* /forum/post/0
> 
> 
> Hey guys...
> 
> 
> I've been burning the midnight oil researching acoustic paneling. I've narrowed down to Owens Corning 705 2" panels doubled up into a 4" frame. I'm going to build a bunch from scratch and place in all locations as possible. However I am having a hell of a time finding a local supplier.
> 
> So far I could only find the Knauf Black face acoustical panels with ECOSE treatment... As that local supplier said it was the 2" OC703 3lb pcf equivelant. A case of (6) 2" panels for about $120 pre tax.
> 
> I'd rather go with the 705 panels if possible... Is there anybody here from the Orange County California that knows of a local place to shop at?... Worst case I could always order online... But shipping approx 6 cases would kill my local tax bracket.



I got my OC703 panels from Macarthur Co. in Anaheim (714) 262-4431.


----------



## Hvacins




> Quote:
> Originally Posted by *Edwoo* /forum/post/0
> 
> 
> 
> I got my OC703 panels from Macarthur Co. in Anaheim (714) 262-4431.



Thanks... I'll definitely give em' a call for for price and availability....


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Edwoo* /forum/post/21478147
> 
> 
> I got my OC703 panels from Macarthur Co. in Anaheim (714) 262-4431.



Me too







- one nice thing is that they sell by the sheet, don't need to round up to a bundle.


----------



## Hvacins




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/0
> 
> 
> 
> Me too
> 
> 
> 
> 
> 
> 
> 
> - one nice thing is that they sell by the sheet, don't need to round up to a bundle.



Brad:


Correct me if I misread... Are you looking to buy? Or did you mean that you already purchased from them? Reason for asking is I'm in the Hvac industry... Funny thing is it never occurred to me that this fiberglass is nearly the same thing as Duct Board. I never use it cause I do heavy commercial work and duct board is typically used for residential. However I hit up my warehouse manager for a supplier and he had me talk to our Rep. Ken at CWCI in Industry. That guy knows all about this stuff as they supply to Edwards theaters and alike for acoustic paneling. Anyway, he's working up pricing on different types and said he'd cut me a good deal. If you or anybody in Orange County CA is in the market for it PM me and we could get a bulk order at a very cost effective price.


----------



## pepar

Maybe not duct board, but certainly duct liner. ( "Linacoustic" for one.)


And I think brad was saying he buys there.


But being in the biz your pricing might be better.


Jeff


----------



## sukumar

My friend is building supe chunks bass traps for four corners. His side surrounds point to front and back walls (dipolar). What would help to reflect sound from surrounds from bass trap , but only absorb low frequency. I guess some membrane is needed for the bass trap over small area facing surrounds.


Front speakers has rear ports. Doe he need to do any changes for bass traps for bass reflecting rear firing ports? Those are only around 1 feet from corner.


I also have exact scenario but plan to measure first. Thanks for your help.


----------



## EBinMD




> Quote:
> Originally Posted by *dragonleepenn* /forum/post/21470405
> 
> 
> You should trap at the bulk head, i have the same bulk head, i use the foam style(for convience) corner wedge traps accross the bulk head. It does work fine, however you can build a soffit in front of the bulk head and fill it with insulation making it a bass trap. You have a cool room, noticed the side wall treatment, i would raise them up mid-way . Is your front wall treated? If not it would help the sound to have it done. You can do a false wall two inches in front, get some ultra touch or roxul or some other material and put it between the false wall studs, either 16"or 24" on center. I bet you will like the improvement. Looks like you need rear treatment and some rear subs, that will also make a big difference in over all sound.



Thanks for the thoughts. I did consider some sort of trap or soffit in front of the bulkhead. That should be pretty easy to do so that might be the next step. I'm thinking a 4" roxul OC703 across the entire length.

Unfortunately, I can't move the front wall at this point. The screen is painted on the wall...What kind of rear treatment would you recommend? Also, what benefit would I get by raising the side wall treatment? I tried the "mirror test", and the reflections do hit them from most seating positions.


----------



## myfipie




> Quote:
> Originally Posted by *sukumar* /forum/post/21478082
> 
> 
> I am planning to measure my room acoustics. I read that ETC is needed. I installed Room Eq wizard and still trying to understand.
> 
> 
> I guess I need following based on my understanding from the forum
> 
> 
> 1. calibrated micro phone
> 
> 2. Pre amp or sound card. Not sure which one I need.
> 
> 
> I am going to use my laptop.
> 
> 
> I read to buy x32 pre amp. I don't mind spending little more. Could you please share good model that works for you. I don't have clue what is this pre amp.
> 
> 
> Do I need External sound card also?
> 
> 
> Please recommend good microphone also.
> 
> Thanks for your time.



You don't need to spend a bunch of money on a pre amp and mic. Ethan did a pretty nice article on the subject.
http://www.realtraps.com/art_measuring.htm


----------



## sukumar




> Quote:
> Originally Posted by *myfipie* /forum/post/21486612
> 
> 
> You don't need to spend a bunch of money on a pre amp and mic. Ethan did a pretty nice article on the subject.
> http://www.realtraps.com/art_measuring.htm



Thanks for the link. I will read it to find what I need.


----------



## sukumar

Here are the photos on how my friend is building bass trap. He is putting thin metal frame that faces his side surrounds. His side surrounds have drives on three sides. He is having Klipsche speakers. There are small holes on the side that faces corner of the wall. Not sure those are bass. Other drivers also pointing to the wall. He intend to cover metal where surrounds waves can hit.


Appreciate any feedback on how bass trap only absorbs bass but reflect HF content.




















Side surround on the corner


----------



## pauleyc




> Quote:
> Originally Posted by *myfipie* /forum/post/21486612
> 
> 
> You don't need to spend a bunch of money on a pre amp and mic. Ethan did a pretty nice article on the subject.
> http://www.realtraps.com/art_measuring.htm



If you don't mind spending a few more $$, the Dayton OmniMic system has gotten some good reviews on AVS. Appears that while REW can provide some additional capabilities .. Dayton OmniMic can be up and running in a matter of minutes and comes with a fully calibrated USB mic (no sound card needed). The price *HAD* dropped from $300 to $250, but it appears its back up to $300.

http://www.parts-express.com/pe/show...number=390-790


----------



## myfipie




> Quote:
> Originally Posted by *pauleyc* /forum/post/21487343
> 
> 
> If you don't mind spending a few more $$, the Dayton OmniMic system has gotten some good reviews on AVS. Appears that while REW can provide some additional capabilities .. Dayton OmniMic can be up and running in a matter of minutes and comes with a fully calibrated USB mic (no sound card needed). The price *HAD* dropped from $300 to $250, but it appears its back up to $300.
> 
> http://www.parts-express.com/pe/show...number=390-790



I am actually testing the system now. Not sure if it really gives me the detail info I want, but might be good for the "get up and go" person. I will let you know what I think after we use it in our lab/test room.


----------



## localhost127




> Quote:
> Originally Posted by *sukumar* /forum/post/21487212
> 
> 
> Thanks for the link. I will read it to find what I need.



also bear in mind support for REQ is available via the HTS forums.


----------



## sukumar




> Quote:
> Originally Posted by *localhost127* /forum/post/21487825
> 
> 
> also bear in mind support for REQ is available via the HTS forums.



Thanks. I am assuming REQ means Room EQ wizard. I will keep in mind.


What is HTS forum?


----------



## sukumar




> Quote:
> Originally Posted by *pauleyc* /forum/post/21487343
> 
> 
> If you don't mind spending a few more $$, the Dayton OmniMic system has gotten some good reviews on AVS. Appears that while REW can provide some additional capabilities .. Dayton OmniMic can be up and running in a matter of minutes and comes with a fully calibrated USB mic (no sound card needed). The price *HAD* dropped from $300 to $250, but it appears its back up to $300.
> 
> http://www.parts-express.com/pe/show...number=390-790



I am still trying to understand function of external sound card.


Why sound card only needed for REW but not for Dayton package?


----------



## pepar

Dayton is self-contained and plugs into USB.


----------



## localhost127




> Quote:
> Originally Posted by *sukumar* /forum/post/21488153
> 
> 
> Thanks. I am assuming REQ means Room EQ wizard. I will keep in mind.
> 
> 
> What is HTS forum?


 http://www.hometheatershack.com/forums/rew-forum/


----------



## mtbdudex




> Quote:
> Originally Posted by *sukumar* /forum/post/21487252
> 
> 
> Here are the photos on how my friend is building bass trap. He is putting thin metal frame that faces his side surrounds. His side surrounds have drives on three sides. He is having Klipsche speakers. There are small holes on the side that faces corner of the wall. Not sure those are bass. Other drivers also pointing to the wall. He intend to cover metal where surrounds waves can hit.
> 
> 
> Appreciate any feedback on how bass trap only absorbs bass but reflect HF content.



Hmmm, is he bonding those metal plates to the fiberglass for any additional bass membrane effect?


Curious if this was swagged or he followed some rationale, look fwd to measurements/results.


The open fiberglass will suck out mid-hi freq, they need to be covered the whole room facing portion to reflect, some use 6mil plastic, I use heavy stock kraft paper bonded to the fiberglass. Details in my sig link.


----------



## sukumar




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21488873
> 
> 
> Hmmm, is he bonding those metal plates to the fiberglass for any additional bass membrane effect?
> 
> 
> Curious if this was swagged or he followed some rationale, look fwd to measurements/results.
> 
> 
> The open fiberglass will suck out mid-hi freq, they need to be covered the whole room facing portion to reflect, some use 6mil plastic, I use heavy stock kraft paper bonded to the fiberglass. Details in my sig link.



I just did pass your reply to him. He decided to cover portion of bass trap that faces towards rear surround with thin metal foil. He thought metal acts like any sheetrock wall as reflector. He is newbie and explored himself. He is just bypassing the basstrap over portion.


I guess it is better to use kraft paper or 6 mil plastic. Do people usually wrap whole triangle piece in plastic and put cloth over it? If he need to use paper, is paper coverd whole length on one side?

I am going to read your thread to get an idea.


Appreciate for the reply.


----------



## sukumar




> Quote:
> Originally Posted by *pepar* /forum/post/21488636
> 
> 
> Dayton is self-contained and plugs into USB.



Good to know. I got calibrated mike which can be connected through usb with my Anthem receiver. Unfortunately, the calibration part is propertiery in file provided by them.


I wonder if I can do rudimentary test with that microphone and built in sound card from the laptop.


----------



## sukumar




> Quote:
> Originally Posted by *localhost127* /forum/post/21488844
> 
> http://www.hometheatershack.com/forums/rew-forum/



Thanks localhost127. I enjoy reading your posts. I took lot of notes from previous posts and need to read them again.


----------



## Hvacins

Took some time the past 2 days drawing and editing this basic floorplan. I will do some more drawings 1 for each wall so you get an idea of how all this fits together. I tried to take a few picks with my camera phone... but its such a small room i cant get it all in one shot. i need to find my good camera and a wide angle lens. I'll post more as i get it done.


Have a look fellas.... I'd like some honest opinions on how to effectivly treat these walls etc. Please let me know if there is something i missed so i can update accordingly. This mainly a 4 person movie room. 7.1 multi channel setup.... actully mainly 5.0 since i still need my proposed subs and my front heights are used every once in a while.

Attachment 234076


----------



## sukumar




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21488873
> 
> 
> Hmmm, is he bonding those metal plates to the fiberglass for any additional bass membrane effect?
> 
> 
> Curious if this was swagged or he followed some rationale, look fwd to measurements/results.
> 
> 
> The open fiberglass will suck out mid-hi freq, they need to be covered the whole room facing portion to reflect, some use 6mil plastic, I use heavy stock kraft paper bonded to the fiberglass. Details in my sig link.



Thanks for your suggestion. Following, my friend removed metal plate and bought 6 mil plastic from Home Depot to wrap the entire triangle piece. He was happy that it also prevents any fiber pieces of material coming out into the room. Then, he will wrap in cotton velvet cloth.


You mentioned if he is doing for bass membrane effect. I am assuming that implies reflect mid high frequency. If it is, yes it is true.


I guess by wrapping in plastic, it only absorbs low frequency from entire piece. I need to look if Bob's index mentions characteristics of plastic.


----------



## Docj04

reading through some of this thread, I've gathered that Roxul is pretty effective and cheaper than OC703/705.


However, for ease of install, is the OC703 stuff more rigid, and thereby a better choice if I simply intend to cover with fabric and hang on the walls?


I have also not seemed to find any Roxul products that are under 3" thick. That may be a little much (and unacceptable for my wife) for living room walls.


Would the 3" roxul require some sort of frame/bracing to maintain shape if I go with it for some of the treatment locations?


Thanks for the help. This thread is great, and I really hope to improve my SQ through treatments very soon!!


----------



## ddgtr

Yes, OC is more rigid but you will still need to build a frame as it's going to be pretty tough to hang otherwise.


----------



## Docj04

Is there a "standard/typical" frame that people are building for the OC (or roxul)?


----------



## Hvacins




> Quote:
> Originally Posted by *Docj04* /forum/post/0
> 
> 
> Is there a "standard/typical" frame that people are building for the OC (or roxul)?



I believe the standard would be 1/2" hardwood by however wide you plan on going with. Example... 1/2"x1" or 1/2"x2" or 1/2"x4" or 1/2"x6".... You can purchase these boards from practically any home builder shop or lumber yard. Try not to use plywood as it tends to split up when running screws through the corners or mounting your hanging hardware. Always pre-drill your holes with a smaller drill bit and use a counter sink bit as well. I would try to find finished or sanded pine planks at minimum... Or use a harder wood like oak but much more pricey. Typically found in the finishing wood department for like custom cabinets and alike. Stay away from ply wood at all costs.


As for hardware.... Look for the single screw heavy duty picture frame mounts. They look like small "D" rings with a mounting tab hanging off it. You then use a simple short wood screw to attach the "D" ring on the upper 1/4 on the back of the side frames, one per side. Then pick up some thin braided heavy duty picture wire and loop it to both rings and tie off. Then all you need is a hook on your wall to hang like your favorite picture. Same idea as found on most expensive canvas art. This is just one of many ways to do it. Many acousticle online retailers have different methods of mounting you could check out as well. The above explanation is for wall mounting.... Hanging from your ceiling or "cloud" suspension is a bit different.


----------



## Hvacins

Here is a few sites to look at amongst many more...
www.realtraps.com 
www.acousticmac.com 
www.atsacoustics.com 
www.gikacoustics.com 
www.readyacoustics.com


----------



## robc1976

Figured I would update with some pics, I have 4 QRD's to be ordered and placed or rear side walls to complete the room.











*Right MLP:*











*Left MLP:*











*Rear wall:*











*QRD diffusor:*


----------



## dormie1360

Hello.


Looks nice. Out of curiosity what are the dimensions of your room? Also, it's hard to tell from the picture, are your wides 60 degrees from center or are they something else.


Regards,

John


----------



## localhost127




> Quote:
> Originally Posted by *robc1976* /forum/post/21504647
> 
> *QRD diffusor:*



just FYI - QRDs should be used periodically, not as a single, stand-alone unit (otherwise equal energy lobes don't form) - and as you use more and more periods, you will want to use Inverse QRDs and adhere to the Barker Code.


----------



## Docj04




> Quote:
> Originally Posted by *Hvacins* /forum/post/21504077
> 
> 
> I believe the standard would be 1/2" hardwood by however wide you plan on going with. Example... 1/2"x1" or 1/2"x2" or 1/2"x4" or 1/2"x6".... You can purchase these boards from practically any home builder shop or lumber yard. Try not to use plywood as it tends to split up when running screws through the corners or mounting your hanging hardware. Always pre-drill your holes with a smaller drill bit and use a counter sink bit as well. I would try to find finished or sanded pine planks at minimum... Or use a harder wood like oak but much more pricey. Typically found in the finishing wood department for like custom cabinets and alike. Stay away from ply wood at all costs.
> 
> 
> As for hardware.... Look for the single screw heavy duty picture frame mounts. They look like small "D" rings with a mounting tab hanging off it. You then use a simple short wood screw to attach the "D" ring on the upper 1/4 on the back of the side frames, one per side. Then pick up some thin braided heavy duty picture wire and loop it to both rings and tie off. Then all you need is a hook on your wall to hang like your favorite picture. Same idea as found on most expensive canvas art. This is just one of many ways to do it. Many acousticle online retailers have different methods of mounting you could check out as well. The above explanation is for wall mounting.... Hanging from your ceiling or "cloud" suspension is a bit different.



Thank you for the great reply. I'm thinking that I may be able to get away with simply standing the fabric wrapped panels on both sides of the corners where my fronts are located (I know--bad to place too close to corners, but it's my living room 1st, theatre 2nd), and bassically use the tower speakers to hold them in place/against the wall. DUE to corner location--thicker paneling is probably better, correct?


What about simply using a staple gun with multiple staples to hold the picture wire to the back side of the panel? Are the 703/705 boards heavy enough to pull themselves out?


----------



## FOH




> Quote:
> Originally Posted by *Docj04* /forum/post/21505362
> 
> 
> Thank you for the great reply. I'm thinking that I may be able to get away with simply standing the fabric wrapped panels on both sides of the corners where my fronts are located (I know--bad to place too close to corners, but it's my living room 1st, theatre 2nd), and bassically use the tower speakers to hold them in place/against the wall. DUE to corner location--thicker paneling is probably better, correct?
> 
> 
> What about simply using a staple gun with multiple staples to hold the picture wire to the back side of the panel? Are the 703/705 boards heavy enough to pull themselves out?




If you've not yet read the fine, comprehensive Ethan Winer tutorial on many of these issues, you may find it of interst. It's here , and quite good.


----------



## robc1976




> Quote:
> Originally Posted by *dormie1360* /forum/post/21505109
> 
> 
> Hello.
> 
> 
> Looks nice. Out of curiosity what are the dimensions of your room? Also, it's hard to tell from the picture, are your wides 60 degrees from center or are they something else.
> 
> 
> Regards,
> 
> John



The camera is a wide angle lens so it makes the picture bigger (The wides appear bigger thatn the mains LOL!!)....they are exactly 60 degrees.


----------



## robc1976




> Quote:
> Originally Posted by *localhost127* /forum/post/21505147
> 
> 
> just FYI - QRDs should be used periodically, not as a single, stand-alone unit (otherwise equal energy lobes don't form) - and as you use more and more periods, you will want to use Inverse QRDs and adhere to the Barker Code.



I have 4 more ordered, may actually get 6 more so I can have a pair on each rear side wall and a put one next to each QRD on the rear wall....VERY good info as always man!


----------



## robc1976




> Quote:
> Originally Posted by *dormie1360* /forum/post/21505109
> 
> 
> Hello.
> 
> 
> Looks nice. Out of curiosity what are the dimensions of your room?
> 
> Regards,
> 
> John



(W)25' X (L)27' ceiling is about 7'2".


----------



## robc1976

The foam behinfd the TV is to kill any hum/buzzing from amps/TV and it works quite well if there are any noises...also looks awesome when watching a movie. I can't get a 242 back there or I would.


----------



## Big Hath

I am working with a small 13' long by 14' wide room with 6'9" walls that slope up to a 9' ceiling. The front wall (where the projector screen and towers will be) has inverted corners. So instead of the walls meeting at a point facing away from the center of the room, there is a painted drywall "column" in the corner with a point facing the center of the room.


The room is carpeted and all walls are textured and painted drywall with no existing acoustical treatments. The back of the room is mostly open but will eventually be covered with thick velvet-like drapery.


How will these inverted corners affect the room acoustics? Am I more or less in need of acoustical treatment for these corners?


----------



## Docj04




> Quote:
> Originally Posted by *FOH* /forum/post/21505998
> 
> 
> If you've not yet read the fine, comprehensive Ethan Winer tutorial on many of these issues, you may find it of interst. It's here , and quite good.



Very informing, indeed.


That basically answered my questions. As with many here--I have "constraints" that I must work within as this is not a dedicated theater room. I can see myself buying some OC705 this week, and getting busy with at least some corner traps, and surrounding my mains and surrounds (tower speakers in corners) with panels on both corner sides. NOT ideal--but most definately an improvement I hope.


...Doesn't help that my living room has:

1. wood floors (larger area rug)

2. 18 foot ceilings

3. Opens into kitchen and front foyer.

4. Acoustic nightmare!!!


----------



## localhost127




> Quote:
> Originally Posted by *Docj04* /forum/post/21506880
> 
> 
> I can see myself buying some OC705 this week, and getting busy with at least some corner traps,



what thickness (or size of facing if doing corner super chunks) are you going with? if of sufficient size, you'll want to use a material with lower flow-resistivity like pink, fluffy attic insulation (uncompressed/loosely filled).


----------



## Docj04

Has anyone heard of this stuff?

http://www.armacell.com/www/armacell...e?OpenDocument 


The fella at SPI told me about it. It's a little more expensive than 703, but no fiberglass.


How does this stuff's abilities compare to OC and/or mineral wool?


...Not sure how to interpret the provided table


----------



## Hvacins




> Quote:
> Originally Posted by *Docj04* /forum/post/0
> 
> 
> Has anyone heard of this stuff?
> 
> http://www.armacell.com/www/armacell...e?OpenDocument
> 
> 
> The fella at SPI told me about it. It's a little more expensive than 703, but no fiberglass.
> 
> 
> How does this stuff's abilities compare to OC and/or mineral wool?
> 
> 
> ...Not sure how to interpret the provided table



I use it almost daily in the A/C industry for thermal pipe wrap or insulation. What I can tell you is this product will come in a roll. It will probably not work all that great for our wall treatments. If you were to stand it on end... It will flop over, cause its not rigid. If you were to make a frame for it, I'd say you would need to install 1/8" door skin or "luan" to the back of the frame. Then glue the armacell to the backing within the frame. If you were to simply set it inside a frame and stand on end.... It would "in time" compress and start to buckle. The other option would be to glue it directly to your wall like you would with the other "foam" style products.


I personally haven't seen anybody mention the use of this product for acoustic panels yet. Probably would be better to stuck with rigid 703 and or 705 panels as that seems to be what most people are using. The roxul brand is mineral wool not fiberglass as previously stated a few pages back, but that is also not as rigid as 703-705 and may need additional support as well. There are some other (green) products out there but they are still a bit more pricey and less rigid as well. Food for thought


----------



## Docj04

For some reason, the URL I pasted goes to the wrong part of the website. There is a selection on that link under products for the "sheet and roll" type product. You are certainly correct, as it can be bought in rolls, but it also shows a panel type piece.


I may head back to SPI today to see if they have some i can compare to the 703 and/or mineral wool.


Once again--Is 705 better than 703 at the same thickness because it is denser???


----------



## localhost127




> Quote:
> Originally Posted by *Docj04* /forum/post/21510147
> 
> 
> Once again--Is 705 better than 703 at the same thickness because it is denser???



better at *what*?


density isn't the key value regarding a porous insulation's absorption characteristics, but *gas-flow-resistivity* (along with thickness, angle of incidence). density and flow-resistivity are generally linear, but two materials with identical densities can have differing flow-resistivity values.


if you read Ethan's paper of which FOH linked to above, you'll know porous insulation is a velocity-based absorber (converts kinetic energy into heat via friction of the waveform passing through the porous material). hence, to be effective, the insulation must be placed in areas of high particle velocity. velocity is zero directly at the boundary (and pressure is max; as pressure and velocity are inversely proportional), hence we generally need thick absorption (or utilize an air-gap to space the insulation away from the boundary) such that the insulation is in areas of high particle velocity for the relevant frequencies.


the problem with higher GFR (denser) materials, is they will begin to reflect at higher frequencies (and grazing angles).

*for broadband panels for reflections:*

normally, one would measure (via the ETC) to identify whether any high-gain early specular reflections are impeding the listening position. some speakers do not throw off-axis energy to the sidewalls, thus there may be no reason to apply broadband absorption in the first place. however, for most speakers, that is not the case.

4" thickness OC703 (3pcf) or Mineral Wool (4pcf) with 2-4" air-gap should be sufficient for the broadband panels to attenuate specular reflections. the lower specular region will extend down to 250-300hz (depending on room dimensions), and typical speakers will increase the amount of off-axis energy dispersed to the side-walls as frequency lowers --- thus, your panels need to be sufficiently thick and effective to attenuate the lower specular region (which also contains inherently more energy content). many use thin absorption which merely attenuates the mid-HF band and allows the lower specular region to persist - coloring, filtering, "EQ'ing" the reflection. i would stay away from OC705 for sidewall panels - they are more expensive than OC703 and can possibly reflect higher freq content.


most batts/panels come in 2" thickness - so you can stack 2 panels together to form a 4" absorber. you can use a dab of 3M spray glue in the corners to bond the two 2" panels together, but DO NOT apply the spray glue to the whole face of the panel - as the glue will block the porous holes and create unexpected results (can become reflective). use just a quick dab in each corner. building a frame out of 1.5"-2" wood will allow you to create an air-gap (spacing the insulation from the boundary, increasing it's effectiveness) as well as make it easy to hang the panel like a picture frame.


also note that as angle of incidence increases (away from 0* normal incidence (perpendicular to the panel), the wave essentially "sees" a thicker panel because when ingress from an angle, it is traveling through more insulation - so the absorption coefficient goes up. HOWEVER, as you approach grazing angles, the panel will begin to REFLECT, just like a stone skipping off water.


in this example, a 4" thick panel is placed flat on the wall/boundary. notice how the blue wave entering at normal incidence (0*, perpendicular from the panel) "sees" a 4" thick porous absorber. the red wave traveling at, say ~50*, comes in diagally at essentially "sees" a thicker panel! however, at high grazing angles (approaching 90* which is parallel to the panel/boundary), the energy grazes off the panel. (very simplified diagram, ignoring many other factors):











here are some examples of how absorption coefficient INCREASES as angle of incidence moves away from normal (thus, the wave "sees" a thicker absorber), and then DECREASES as angle of incidence approaches grazing angle.


































































now, for the modal region (bass/LF), the energy has wave properties and can no longer be modeled like specular energy (geometry). the waves are huge thus we place the absorber in the corner where the boundaries force the energy through the insulation (vs the large wavelengths simply diffracting around the panels). 3D corners will attack all 3 axial modes in the room, and 2D corners will attack the 2 axial modes relevant to those 2 boundaries.


for the corner porous bass traps (LF absorbers), if you are using a relatively thin panel then the denser is better. but since porous insulation is a velocity-based absorber, there is really no point in using thin absorption here (regardless of density/GFR). the LF modal wavelengths are large and contain the most energy content - thus the LF porous corner absorbers need to be as thick as possible. when building thicker and thicker corner traps, you need to use a material with lower gas-flow-resistivity. pink fluffy attic insulation (loosely filled/uncompressed) will perform best for LF absorber if you can build 34" faced traps or thicker. it will be a cheaper and more effective solution.


pink fluffy is 5000rayls/s gas-flow-resistivity

OC703 is 16,700rayls/s (but NASA tested somewhere around 37,000 IIRC (document is at home). OC705 is even higher GFR.


200mm










300mm w/ 300mm air-gap:


http://imgur.com/buwNv.gif%5B/IMG%5D



a very common misconception is that denser is better! as you make the corner trap thicker and thicker (with denser material), the energy can no longer penetrate through all of the small, porous holes, and essentially the corner "absorber" begins to reflect! it is still not very well accepted that thick traps made from low GFR material perform better, but what can you do...


another issue is, you really cannot have too much LF porous absorption within a room ... but the LF porous absorber will also inadvertantly absorb specular energy within the room as well! with lots of surface area and thick corner traps (required for effective LF absorption), you will create a very dead/damped room. thus, we generally apply a reflective membrane to the corner bass traps such that some mid-HF specular energy is reflective to preserve energy within the room. you can use 6mil plastic to wrap your corner bass traps in ... as bass traps do not need acoustically transparent fabric like the broadband panels do.


----------



## FOH

^^^


Killer post local










Good lookin' out wrt grazing angles/angle of incidence in general.


What's the definition of 2% perforated panel? Also, the final graphic "300mm w/ 300mm air-gap", seems a combo of the two would offer the ideal characteristics. Not acoustically in series, but perhaps half and half,...ever seen such a thing around GS or elsewhere?


Also, ever seen these plastic wrapped batts? Not sure how the plastic thickness affects things, however at least they'd be a pleasure to handle. They seem ideal


----------



## Docj04












That post was amazing and interesting as can be. Thank's for that. I believe that I have made a decision regarding what combinations I will be using.


I will likely go with 3" mineral wool behind the front and rear speakers which are in corners. (I will basically "line" the corners with the 2X4' panels,as my tower speakers are 39" tall).


Then, I will likely use OC703 panels covered in fabric in a few places on the walls themselves.


I have to believe ( and REALLY hope) that I will hear an improvement, as my living room has ZERO treatment thus far, and with 18' celings/wallls and wood floors--I've got an acoustic mess!


----------



## fotto

Very informative post Local...nice job.


----------



## NicksHitachi




> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> 
> better at *what*?
> 
> 
> density isn't the key value regarding a porous insulation's absorption characteristics, but gas-flow-resistivity (along with thickness, angle of incidence). density and flow-resistivity are generally linear, but two materials with identical densities can have differing flow-resistivity values.
> 
> 
> if you read Ethan's paper of which FOH linked to above, you'll know porous insulation is a velocity-based absorber (converts kinetic energy into heat via friction of the waveform passing through the porous material). hence, to be effective, the insulation must be placed in areas of high particle velocity. velocity is zero directly at the boundary (and pressure is max; as pressure and velocity are inversely proportional), hence we generally need thick absorption (or utilize an air-gap to space the insulation away from the boundary) such that the insulation is in areas of high particle velocity for the relevant frequencies.
> 
> 
> the problem with higher GFR (denser) materials, is they will begin to reflect at higher frequencies (and grazing angles).
> 
> 
> for broadband panels for reflections:
> 
> normally, one would measure (via the ETC) to identify whether any high-gain early specular reflections are impeding the listening position. some speakers do not throw off-axis energy to the sidewalls, thus there may be no reason to apply broadband absorption in the first place. however, for most speakers, that is not the case.
> 
> 
> 4" thickness OC703 (3pcf) or Mineral Wool (4pcf) with 2-4" air-gap should be sufficient for the broadband panels to attenuate specular reflections. the lower specular region will extend down to 250-300hz (depending on room dimensions), and typical speakers will increase the amount of off-axis energy dispersed to the side-walls as frequency lowers --- thus, your panels need to be sufficiently thick and effective to attenuate the lower specular region (which also contains inherently more energy content). many use thin absorption which merely attenuates the mid-HF band and allows the lower specular region to persist - coloring, filtering, "EQ'ing" the reflection. i would stay away from OC705 for sidewall panels - they are more expensive than OC703 and can possibly reflect higher freq content.
> 
> 
> most batts/panels come in 2" thickness - so you can stack 2 panels together to form a 4" absorber. you can use a dab of 3M spray glue in the corners to bond the two 2" panels together, but DO NOT apply the spray glue to the whole face of the panel - as the glue will block the porous holes and create unexpected results (can become reflective). use just a quick dab in each corner. building a frame out of 1.5"-2" wood will allow you to create an air-gap (spacing the insulation from the boundary, increasing it's effectiveness) as well as make it easy to hang the panel like a picture frame.
> 
> 
> also note that as angle of incidence increases (away from 0* normal incidence (perpendicular to the panel), the wave essentially "sees" a thicker panel because when ingress from an angle, it is traveling through more insulation - so the absorption coefficient goes up. HOWEVER, as you approach grazing angles, the panel will begin to REFLECT, just like a stone skipping off water.
> 
> 
> in this example, a 4" thick panel is placed flat on the wall/boundary. notice how the blue wave entering at normal incidence (0*, perpendicular from the panel) "sees" a 4" thick porous absorber. the red wave traveling at, say ~50*, comes in diagally at essentially "sees" a thicker panel! however, at high grazing angles (approaching 90* which is parallel to the panel/boundary), the energy grazes off the panel. (very simplified diagram, ignoring many other factors):
> 
> 
> here are some examples of how absorption coefficient INCREASES as angle of incidence moves away from normal (thus, the wave "sees" a thicker absorber), and then DECREASES as angle of incidence approaches grazing angle.
> 
> 
> now, for the modal region (bass/LF), the energy has wave properties and can no longer be modeled like specular energy (geometry). the waves are huge thus we place the absorber in the corner where the boundaries force the energy through the insulation (vs the large wavelengths simply diffracting around the panels). 3D corners will attack all 3 axial modes in the room, and 2D corners will attack the 2 axial modes relevant to those 2 boundaries.
> 
> 
> for the corner porous bass traps (LF absorbers), if you are using a relatively thin panel then the denser is better. but since porous insulation is a velocity-based absorber, there is really no point in using thin absorption here (regardless of density/GFR). the LF modal wavelengths are large and contain the most energy content - thus the LF porous corner absorbers need to be as thick as possible. when building thicker and thicker corner traps, you need to use a material with lower gas-flow-resistivity. pink fluffy attic insulation (loosely filled/uncompressed) will perform best for LF absorber if you can build 34" faced traps or thicker. it will be a cheaper and more effective solution.
> 
> 
> pink fluffy is 5000rayls/s gas-flow-resistivity
> 
> OC703 is 16,700rayls/s (but NASA tested somewhere around 37,000 IIRC (document is at home). OC705 is even higher GFR.
> 
> 
> 200mm
> 
> 
> 300mm w/ 300mm air-gap:
> 
> 
> a very common misconception is that denser is better! as you make the corner trap thicker and thicker (with denser material), the energy can no longer penetrate through all of the small, porous holes, and essentially the corner "absorber" begins to reflect! it is still not very well accepted that thick traps made from low GFR material perform better, but what can you do...
> 
> 
> another issue is, you really cannot have too much LF porous absorption within a room ... but the LF porous absorber will also inadvertantly absorb specular energy within the room as well! with lots of surface area and thick corner traps (required for effective LF absorption), you will create a very dead/damped room. thus, we generally apply a reflective membrane to the corner bass traps such that some mid-HF specular energy is reflective to preserve energy within the room. you can use 6mil plastic to wrap your corner bass traps in ... as bass traps do not need acoustically transparent fabric like the broadband panels do.



LH,


Why is pink fluffy a better solution for corner traps if it has 3x lower gfr than OC703? It should be calculable to determine at what density and thickness of different materials certain frequencies begin to be reflected. Why not a table then? I can see where this is possible but at what thickness does this affect the frequencies we're targeting for corner traps?


Why is it not commonly accepted that pink fluffy is better? I have seen you are quite the activist for this position, do experts in acoustics generally agree or disagree with this statement?


----------



## nickbuol




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21511259
> 
> 
> Why is it not commonly accepted that pink fluffy is better? I have seen you are quite the activist for this position, do experts in acoustics generally agree or disagree with this statement?



I posed a similar question a few months ago in this massive thread, and it started a pi$$ing match between some folks. I wasn't convinced that the pink fluffy was any better, but I would really like for some simple, no-nonsense proof that it is since it is definitely a lot cheaper. Unfortunately, it would probably take one of us "average" users to measure a room, then put up a pink fluffy trap and measure, and lastly, take down the pink fluffy trap and make a super chunk or straddling trap out of the OC703 or 705 stuff and measure again. Post the results, and see what happens.


My theater is still in the construction phase and will be for a while since I am finishing my entire basement at the same time, plus I will have so much other stuff to fix, that I won't have the time to dedicate to the testing, building, testing, building, and testing. If I had to do all of that, I would skip the pink fluffy and just go with the 703/705 stuff since I would need to buy/build it anyway for the test.


----------



## Hvacins

LH127:


Now that lengthy post is impressive!!!







2 thumbs up and a handshake. Thanks for the great info.... Now I need to cut and paste to my desk top for quick reference.


----------



## localhost127




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21511259
> 
> 
> LH,
> 
> 
> Why is pink fluffy a better solution for corner traps if it has 3x lower gfr than OC703?



porous insulation is a velocity-based absorber - and must be placed throughout areas of high particle velocity in order to be effective. the modal-region wavelengths are very long, which requires thick porous absorbers. as you make thicker and thicker traps, you are making it more difficult for sound to penetrate through the series of interconnected pores of the material. with too high a GFR, the impedance mismatch between the air and the absorbent will causes the sound to reflect from the outer-face.


think of it this way - the acoustically transparent (porous) fabric you use for your broadband panels...has low flow resistivity and allows sound to pass through it freely (close surface impedance to air). you can freely blow through it (and that is the test we tell people to use when procuring). now, double up the layer and try blowing through it again. continue adding layers (increasing thickness), and eventually air will not be able to freely pass through the porous holes of the fabric and it will instead reflect off (very high GFR).


thus, as the thickness of the absorber is increased, it will become more effective to use a material with lower gas-flow-resistivity such that the sound can still penetrate through the material.




















via: http://www.amazon.com/Acoustic-Absor.../dp/0415471745 



> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21511259
> 
> 
> It should be calculable to determine at what density and thickness of different materials certain frequencies begin to be reflected. Why not a table then? I can see where this is possible but at what thickness does this affect the frequencies we're targeting for corner traps?


 http://www.whealy.com/acoustics/Porous.html 

*note:* _"The transfer matrix calculations in this spreadsheet are reimplementations of the MATLAB scripts printed in Appendix B of the first edition of Trevor Cox and Peter D'Antonio's book *Acoustic Absorbers and Diffusors. Theory, Design and Application .*"_


AMFG SoundFlow:
http://soundflow.afmg.eu/index.php/sf-features-en.html 

(and this is without going into details of particular methods of obtaining absorption coefficients, and which are necessarily relevant - for simplicity).




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21511259
> 
> 
> Why is it not commonly accepted that pink fluffy is better? I have seen you are quite the activist for this position, do experts in acoustics generally agree or disagree with this statement?



anywhere professional is likely going to be using a combination, but primarily resonator/tuned traps (pressure-based absorbers, thus not limited to the thickness requirements of porous, velocity-based absorbers). thick, broadband porous traps are more likely found in diy environments (relatively cheap to construct, materials easy to procure, little design work, works without trial-and-error as with tuned traps).


the diy community is generally constricted to very small rooms, which is not ideal due to having little real estate for such thick, porous LF absorbers. the issues are compounded because the modal issues become more detrimental as the room becomes smaller, yet simultaneously, as the room becomes smaller you have less room for effective porous LF absorption. resonator (pressure-based traps) are more difficult to construct, but are more efficient when placed in areas of high particle pressure (which, conveniently, is against the boundary).


and actually, it is commonly accepted re: pink fluffy (low GFR), just not in such areas as this and many other forums within the DIY audio crowd. the "oc703 superchunks ©" have been shown to be effective, thus they are copied and utilized within the diy community without little questioning as to the details. the strange thing is that people automatically misassume that denser is better, and always seem to ask questions regarding "the next denser product", and whether that will perform any better? but it's funny to think about how many dont even consider to ask questions in the other direction regarding less dense (lower GFR) material. it's always towards the denser spectrum that questions are presented.


there seems to be little discussion of porous material characteristics and details for optimal LF absorption except in a few areas. such continued assumptions and general lack of understanding of the components are probably why there is a general stigma regarding porous absorption that many seem to chime in with, regarding that "it is useless because it cannot absorb below 125, 100hz, etc".



edit:



> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21511259
> 
> 
> Why is it not commonly accepted that pink fluffy is better?



because of responses like this that ignore any of the data and continue to believe that their intuition regarding acoustics is never wrong?



> Quote:
> Originally Posted by *nickbuol* /forum/post/21511877
> 
> 
> If I had to do all of that, I would skip the pink fluffy and just go with the 703/705 stuff since I would need to buy/build it anyway for the test.



the bulk of my intuitions have been proven wrong over and over - welcome to acoustics


----------



## localhost127

here is the NASA document - they put oc703 at 27,000 (not 16,000rayls as commonly asserted):
http://ntrs.nasa.gov/archive/nasa/ca...1988003624.pdf 











the lighter (3350 @ 4100rayl/s) vs OC703


----------



## Taxi

So given the above (And thank you localhost127!) it seems that it should be relatively easy to determine the maximum effective size of a corner bass trap made out of OC703 vs. "Pink Fluffy", since we know the shape (triangular) and the GFR values for this material.


That might make it easier to recommend one material over the other when people have questions about building these types of bass traps. (For example: Under 12" face = no impact, 12" to 24" face = OC703, Over 24" = Pink Fluffy)


I don't understand the formulas myself, or I'd make the attempt.


----------



## localhost127

hannes offers some nice commentary and diagrams:
http://www.gearslutz.com/board/6328646-post88.html 

http://www.gearslutz.com/board/6281432-post46.html 

http://www.gearslutz.com/board/1913176-post29.html 










and as he noted, if denser is better, then why does oc701 outperform oc703, oc705 in this example - and notice how the lightest material performs best at 125hz (relative to other materials).












> Quote:
> Originally Posted by *SAC/dragonfyr* /forum/post/0
> 
> 
> As Andre states, you are dealing with the acoustical Impedance of the boundary material.
> 
> 
> Please note this and be careful as so many are want to reduce absorption to resistance - which is only one part of the complex impedance.
> 
> 
> And this issue becomes very important if one stops for a moment and examines that the the reactance has both capacitive and inductive components which function not only as frequency selective resistance with a time aspect, but which also impact the energy aspects of the system behavior, as the real domain which corresponds to resistance also correlates to the potential energy in the system, while the imaginary realm corresponds to the reactance component and the kinetic energy of the system, which relate directly with pressure and velocity aspects (and more) of the overall system.
> 
> 
> One makes a significant mistake to reduce the absorption model to simply a function of 'resistance'.




more if interested:

http://www.gearslutz.com/board/studi...q-4-avare.html 

http://downloads.bbc.co.uk/rd/pubs/reports/1992-11.pdf 

(note fig9 pg4 - covering porous bass traps with reflective plastic membrane to reflect mid-hf specular content back into the room):










http://www.rockwool.it/files/RW-IT/f..._vers3_web.pdf (section 2)

http://www.rockwool.it/download/software 


oh, and on the subject of this (flow-resistivity along with oc703/superchunks), it may be wise to note that the flow-resistivity of oc703 when mounted as a panel on a boundary will be different than a oc703 superchunk --- in the superchunk, the "edge" of the individual oc703 panel (before cutting) is functioning as the outer-face of the absorber.


----------



## localhost127




> Quote:
> Originally Posted by *FOH* /forum/post/21510993
> 
> 
> What's the definition of 2% perforated panel? Also, the final graphic "300mm w/ 300mm air-gap", seems a combo of the two would offer the ideal characteristics. Not acoustically in series, but perhaps half and half,...ever seen such a thing around GS or elsewhere?



in that model, ...only if you had a very specific issue at ~24hz ... and if so, you wouldn't be able to implement both within the same corner. efforts would be better spent with resonator trap for the specific, low octave issue (and porous absorption for broadband). any mixing of the two in the same corner would yield impedance issues (could likely be modeled via SoundFlow) - but not entirely predictable (eg, depends on how wave is incident to corner).



> Quote:
> Originally Posted by *FOH* /forum/post/21510993
> 
> 
> Also, ever seen these plastic wrapped batts? Not sure how the plastic thickness affects things, however at least they'd be a pleasure to handle. They seem ideal



you would have many instances of impedance changes throughout the trap.


----------



## Docj04

Acoustic Performance

*Acoustic Performance


Random incidence

absorption coefficient

acc. to EN ISO 354 125 250 500 1 000 2 000 4 000


at 10 mm 0.02 0.04 0.08 0.19 0.53 0.44


at 32 mm 0.08 0.17 0.51 0.56 0.25 0.24*

This is the absorbtion table (i think) from the armaflex website that my local SPI insulation warehouse manager recommended. It's supposedly nice and rigid, requiring no frame, and is fairly cost competitive with other options. Can anyone evaluate this table an comment on the effectiveness of this product???


Sorry that the table is out of alignment, at 125, the 0.02 and 0.08 should be directly underneath


----------



## myfipie




> Quote:
> Originally Posted by *Docj04* /forum/post/21515631
> 
> 
> Acoustic Performance
> 
> *Acoustic Performance
> 
> 
> Random incidence
> 
> absorption coefficient
> 
> acc. to EN ISO 354 125 250 500 1 000 2 000 4 000
> 
> 
> at 10 mm 0.02 0.04 0.08 0.19 0.53 0.44
> 
> 
> at 32 mm 0.08 0.17 0.51 0.56 0.25 0.24*
> 
> This is the absorbtion table (i think) from the armaflex website that my local SPI insulation warehouse manager recommended. It's supposedly nice and rigid, requiring no frame, and is fairly cost competitive with other options. Can anyone evaluate this table an comment on the effectiveness of this product???
> 
> 
> Sorry that the table is out of alignment, at 125, the 0.02 and 0.08 should be directly underneath



You are going to want to make those no less then 100mm thick and straddle corners if you want to use them as broad band bass traps. Honestly I would recommend thicker then that if you can.


----------



## myfipie




> Quote:
> Originally Posted by *robc1976* /forum/post/21504647
> 
> 
> Figured I would update with some pics, I have 4 QRD's to be ordered and placed or rear side walls to complete the room.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Right MLP:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Left MLP:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Rear wall:*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *QRD diffusor:*



Wow I need to get these up on our face book page (and our website on the next update). If you are on face book would you mind posting them over on our page?


----------



## Docj04




> Quote:
> Originally Posted by *myfipie* /forum/post/21516274
> 
> 
> You are going to want to make those no less then 100mm thick and straddle corners if you want to use them as broad band bass traps. Honestly I would recommend thicker then that if you can.



Given that Reply, I surmise that these are NOT as effective as OC703/705 at the same 1" thickness.


----------



## Brad Horstkotte

No, not as good - does that material have a paper facing? Not sure why else the absorption would be so bad at the top end.


703 1" (25mm) on wall 0.11 0.28 0.68 0.90 0.93 0.96

Armaflex 32 mm (1.26") 0.08 0.17 0.51 0.56 0.25 0.24


I think myfipie's comment applies regardless of the material - 4"+ and air space behind at a minimum for bass trapping.


----------



## Docj04




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21517145
> 
> 
> No, not as good - does that material have a paper facing? Not sure why else the absorption would be so bad at the top end.
> 
> 
> 703 1" (25mm) on wall 0.11 0.28 0.68 0.90 0.93 0.96
> 
> Armaflex 32 mm (1.26") 0.08 0.17 0.51 0.56 0.25 0.24
> 
> 
> I think myfipie's comment applies regardless of the material - 4"+ and air space behind at a minimum for bass trapping.



Got it. I don't think there is a paper facing. The website is Armacell.com, and under products, you will find the Armaflex rolls and sheets. There is full description there.


looks like it's going to be Plan A--combination of mineral wool to line the corners where the tower speakers are as I can simply stand them up and use the speakers themselves to hold them in place, and OC703 panels (for rigidity) hung in various wall locations.


Should be better than nothing, which is what I have now...


----------



## Brad Horstkotte

Mineral wool works well for bass trapping, and is usually cheaper then rigid fiberglas - but of course, it takes a different approach to mount.


----------



## pepar

More volume, too, right?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *pepar* /forum/post/21518454
> 
> 
> More volume, too, right?



Do you mean you'd need more volume of mineral wool? My understanding is that that's more impacted by density than the material type - i.e. ~3 pcf mineral wool performs similarly inch for inch compared to ~3 pcf rigid fiberglas. Maybe you meant lighter density, like pink fluffy?


----------



## pepar




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21518574
> 
> 
> Do you mean you'd need more volume of mineral wool? My understanding is that that's more impacted by density than the material type - i.e. ~3 pcf mineral wool performs similarly inch for inch compared to ~3 pcf rigid fiberglas. *Maybe you meant lighter density, like pink fluffy*?



Yeah, that's it.


----------



## localhost127

Docj,

do you have any photos of your space you're willing to share? would assist with recommendations on placement and approach -


----------



## Docj04




> Quote:
> Originally Posted by *localhost127* /forum/post/21518846
> 
> 
> Docj,
> 
> do you have any photos of your space you're willing to share? would assist with recommendations on placement and approach -



Actually, I will likely snap some digital pics this weekend to post here. The only reason that I haven't done so already is because I am having a carpenter come and lower the mantle shelf above my fireplace (gas, and NEVER even turned on) so that I can mount my Sharp 70" LED above it.

This will, of course, change my speaker layout and therefore my acoustic treatment placement as well.


I will likely go today to buy a bundle of mineral wool panels to have ready, and then get whatever else I need once the room is rearranged.


----------



## Docj04

Well, I got a 6-pack of 2'x4x1.5"', and a roll of burlap to cover it...


HATE the mineral wool. $30 for the panels,and $60 for the burlap = lessoned learned about the mineral wool.Too floppy and easily torn/damaged.


I'll end up keeping the mineral wool for odds and ends, and getting some 703 instead.


----------



## myfipie




> Quote:
> Originally Posted by *Docj04* /forum/post/21524628
> 
> 
> Well, I got a 6-pack of 2'x4x1.5"', and a roll of burlap to cover it...
> 
> 
> HATE the mineral wool. $30 for the panels,and $60 for the burlap = lessoned learned about the mineral wool.Too floppy and easily torn/damaged.
> 
> 
> I'll end up keeping the mineral wool for odds and ends, and getting some 703 instead.



Yes with mineral wool you really do need to use a frame when making panels, but can be nice when cut into triangles and stacked in the corners.


----------



## Eyleron

A couple of my corners can only be 24" face corner traps, due to space limitations. Using the Whealy calculator, I tried a few different depths. A 24" face corner trap has a maximum depth of 24 inches (if sound were to enter at a very oblique angle almost parallel to the large 24" face). But that's only at one point. At two other points it has has 17", 8", and 6" of depth, etc. [EDIT: Removed mean and average calculated depth stuff]


So I decided to graph the absorption curves for several low bass frequencies, by inputting into the Porous Absorber Calculator the depth in mm of each half inch slide: 24", 12", 11", 6", etc. for each of seven frequencies.


----------



## HKman

They may be a stupid question but I used this DIY method to make some cheap acoustic panelling:

http://www.amateurhometheater.com/di...ic_panels.html 


I used pretty much the same duct board. Obviously, fiberglass isn't good for you and every time I handled it, there is usually a slight irritation if it comes in contact with skin.


Now that the project is done and the panels are up, I'm beginning to worry that this may not be good to breathe in and if there are any asbestos type concerns. I know it would be a huge waste of time and money if I take these down and throw them out but health is first. I'm assuming that because they are covered in speaker cloth, they should be fine.


Any re-assurance or warning bells?


----------



## nezff




> Quote:
> Originally Posted by *HKman* /forum/post/21589462
> 
> 
> They may be a stupid question but I used this DIY method to make some cheap acoustic panelling:
> 
> http://www.amateurhometheater.com/di...ic_panels.html
> 
> 
> I used pretty much the same duct board. Obviously, fiberglass isn't good for you and every time I handled it, there is usually a slight irritation if it comes in contact with skin.
> 
> 
> Now that the project is done and the panels are up, I'm beginning to worry that this may not be good to breathe in and if there are any asbestos type concerns. I know it would be a huge waste of time and money if I take these down and throw them out but health is first. I'm assuming that because they are covered in speaker cloth, they should be fine.
> 
> 
> Any re-assurance or warning bells?



I didnt use fiberglass for this reason.


----------



## localhost127




> Quote:
> Originally Posted by *nezff* /forum/post/21589471
> 
> 
> I didnt use fiberglass for this reason.


 http://www.gearslutz.com/board/bass-...rs-review.html


----------



## HKman

So....get rid of it???


That double sided tape is going to mean some re-painting as well.


----------



## nezff




> Quote:
> Originally Posted by *localhost127* /forum/post/0
> 
> 
> http://www.gearslutz.com/board/bass-...rs-review.html



So blue jeans and newspaper shouldn't be in our homes but metal slag and glass fibers are ok because they will break down.


----------



## HKman

Is the fact that the the surface of the fiberglass has been spray-glued (to fix to the speaker cloth) and is fully covered by speaker cloth make any difference?


----------



## myfipie




> Quote:
> Using the Whealy calculator, I tried a few different depths. A 24" face corner trap has a maximum depth of 24 inches (if sound were to enter at a very oblique angle almost parallel to the large 24" face).



Good stuff but

When you straddle the corner it is much more effective then what you posted. I did a quick test of our lab/test room with 8 Monster traps. 3 corners floor to ceiling and 2 on the back wall. Pretty much follows the results we got from Riverband Lab when we tested there. Which shows a great deal of absorption below 100 hz. Note I would want to put in even more treatment but it is pretty close to a 10 db window which is pretty impressive with a great deal of improvement at 67hz.


----------



## localhost127




> Quote:
> Originally Posted by *HKman* /forum/post/21589882
> 
> 
> Is the fact that the the surface of the fiberglass has been spray-glued (to fix to the speaker cloth) and is fully covered by speaker cloth make any difference?



fiberglass is a _porous_ material - it works by converting kinetic energy of the soundwave traversing through the series of porous ducts within the insulation into heat (friction). by coating the face of the insulation with a spray or glue, you are blocking the porous holes, restricting flow through the absorber - yielding unexpected results (reflection due to impedance change). you do not want to use spray or glue to coat the face of the insulation to bond fabric. maybe a small dab of 3M spray in the corners...


----------



## Eyleron




> Quote:
> Originally Posted by *myfipie* /forum/post/21590598
> 
> 
> Good stuff but
> 
> When you straddle the corner it is much more effective then what you posted. I did a quick test of our lab/test room with 8 Monster traps. 3 corners floor to ceiling and 2 on the back wall. Pretty much follows the results we got from Riverband Lab when we tested there. Which shows a great deal of absorption below 100 hz. Note I would want to put in even more treatment but it is pretty close to a 10 db window which is pretty impressive with a great deal of improvement at 67hz.



I'm not sure what you're saying/showing. That 8 Monster traps with better performance in a room, versus one theoretical slice of 24" fluffy at 60 Hz?


I don't know if it matters, but using the same calculator, with a 4" thick material of 16,000 rayls (is this approximately the gas flow resistivity of a Monster trap?), with a 15" gap (the longest dimension air gap to the wall corner using a 2 foot-wide trap that isn't tapered to fit snug to the edges of the corner), I get .53 absorption coefficient at 60 Hz.


If the trap was had tapered edges to fit snug into a corner, then the longest dimension of air gap would be 17". Switching to 10,000 rayls yields .69 absorbtion.


----------



## localhost127




> Quote:
> Originally Posted by *nezff* /forum/post/21589699
> 
> 
> So blue jeans and newspaper shouldn't be in our homes but metal slag and glass fibers are ok because they will break down.


----------



## sukumar




> Quote:
> Originally Posted by *localhost127* /forum/post/21590793
> 
> 
> fiberglass is a _porous_ material - it works by converting kinetic energy of the soundwave traversing through the series of porous ducts within the insulation into heat (friction). by coating the face of the insulation with a spray or glue, you are blocking the porous holes, restricting flow through the absorber - yielding unexpected results (reflection due to impedance change). you do not want to use spray or glue to coat the face of the insulation to bond fabric. maybe a small dab of 3M spray in the corners...



Unless there is air gap on the back, does it make difference if sound waves hit glue or wall to reflect back? Also, if it is just meant for high frequency absorber instead of basstrap, the material should absorb all of it by the time it reaches back right?


I just want to clarify if the reason is not valid.


----------



## sukumar

Is rockwool same as pink stuff? I read from localhost127 posts that it is best to absorb/pass waves.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *sukumar* /forum/post/21591584
> 
> 
> Is rockwool same as pink stuff? I read from localhost127 posts that it is best to absorb/pass waves.



No, its not the same - pink stuff is made of fiberglas, rock wool (a.k.a. mineral wool) is made from stone fibers. Pink fluffy is lower density than most mineral wool (although I'm sure there are different densities available of both, just speaking of the most common stuff).


----------



## localhost127




> Quote:
> Originally Posted by *sukumar* /forum/post/21591524
> 
> 
> Unless there is air gap on the back, does it make difference if sound waves hit glue or wall to reflect back? Also, if it is just meant for high frequency absorber instead of basstrap, the material should absorb all of it by the time it reaches back right?
> 
> 
> I just want to clarify if the reason is not valid.



if no air gap and the panel is flat against rigid boundary, then it will not make a difference. but by not utilizing an air-gap, you are eliminating your "free lunch".


what is your definition of a "high frequency absorber"? in the specular region, the lower frequencies have longer wavelengths with inherently more energy content. thus, attention for broadband panel absorbers generally needs to be with regards to the lower end of the specular region.


----------



## sukumar




> Quote:
> Originally Posted by *localhost127* /forum/post/21592035
> 
> 
> if no air gap and the panel is flat against rigid boundary, then it will not make a difference. but by not utilizing an air-gap, you are eliminating your "free lunch".



With air gap it makes sense. Regarding air gap, I have question. If super chunk bass trap is made with oc 703, does it make difference if 24 inch deep oc 703 vs 12 inch oc 703 and 12 inch airgap? Since oc 703 is cheaper, it is easy to make 24 inch bass traps to stand stable.


Also if volume remaining constant, does filling pink stuff for the same volume more effective than oc 703?



> Quote:
> Originally Posted by *localhost127* /forum/post/21592035
> 
> 
> what is your definition of a "high frequency absorber"? in the specular region, the lower frequencies have longer wavelengths with inherently more energy content. thus, attention for broadband panel absorbers generally needs to be with regards to the lower end of the specular region.



I meant panels for first reflections need to be high frequency absorber. I remember absorption coefficient for 4 inch panels for high frequencies is close to or equal to 1. In this case, by the time sound reaches to the back, I thought they would have been absorbed.


----------



## localhost127




> Quote:
> Originally Posted by *sukumar* /forum/post/21592241
> 
> 
> I meant panels for first reflections need to be high frequency absorber. I remember absorption coefficient for 4 inch panels for high frequencies is close to or equal to 1. In this case, by the time sound reaches to the back, I thought they would have been absorbed.



so, you're referring to specular reflection absorbers, NOT merely high frequency absorber. the specular region extends down to ~250hz (ignoring room dimensions for simplicity) ... why are you so concerned with HF frequencies of which have little energy content to begin with? that's the entire point behind using appropriate thickness - with focus on the lower specular region of which has longer wavelengths with inherently more energy content! ... of which also are generally more "off-axis" than the higher (more directional) frequencies.


----------



## Eyleron

For non-specular bass, like 120 hz, should we consider it to always be "normal" to the surface of an absorber (and likewise every surface of the room),

or is it considered to still have propagated from the location of the loudspeaker and thus has an angle?


And for higher frequencies of diffuse sound fields (which I hear you need a larger room for), does one consider those to always be normal, or do you consider them to be hitting absorbers / diffusers from every angle normal and oblique, because to be diffuse they must be bouncing around from hundreds of different angles?


----------



## localhost127




> Quote:
> Originally Posted by *Eyleron* /forum/post/21592438
> 
> 
> For non-specular bass, like 120 hz, should we consider it to always be "normal" to the surface of an absorber (and likewise every surface of the room),
> 
> or is it considered to still have propagated from the location of the loudspeaker and thus has an angle?
> 
> 
> And for higher frequencies of diffuse sound fields (which I hear you need a larger room for), does one consider those to always be normal, or do you consider them to be hitting absorbers / diffusers from every angle normal and oblique, because to be diffuse they must be bouncing around from hundreds of different angles?



there is no reverberant (diffuse) sound-field in small acoustical spaces. hence why absorption coefficients via reverberant chamber are not directly relate-able (but give good indication between performance of materials measured within the same setup). this is why normal incidence (impedance tube) is preferred.


the PAC most certainly has limitations.


----------



## neo95gt

Does anyone in here have real world experience with fiberglass vs. roxul? I know most people around these parts are of the opinion that roxul is just not worth it....and the stats back it up. However, the people that I do know that used it (contractors and friends) say that it is worth it and there is a noticeable difference between the two. Any thoughts?


Of course I'll be using the other sound isolation methods as well, but people seem to love this roxul safe n sound stuff (and the cotton stuff) for sound barrier applications.


----------



## Al Sherwood




> Quote:
> Originally Posted by *neo95gt* /forum/post/21596229
> 
> 
> Does anyone in here have real world experience with fiberglass vs. roxul? I know most people around these parts are of the opinion that roxul is just not worth it....and the stats back it up. However, the people that I do know that used it (contractors and friends) say that it is worth it and there is a noticeable difference between the two. Any thoughts?
> 
> 
> Of course I'll be using the other sound isolation methods as well, but people seem to love this roxul safe n sound stuff (and the cotton stuff) for sound barrier applications.



Ditto, on the Roxul, I was wondering the same thing...


----------



## dormie1360

I see the term "small" and "large" acoustical spaces/rooms frequently used. Is there a ballpark ft/3 range when talking about small vs large?


John


----------



## dragonleepenn




> Quote:
> Originally Posted by *neo95gt* /forum/post/21596229
> 
> 
> Does anyone in here have real world experience with fiberglass vs. roxul? I know most people around these parts are of the opinion that roxul is just not worth it....and the stats back it up. However, the people that I do know that used it (contractors and friends) say that it is worth it and there is a noticeable difference between the two. Any thoughts?
> 
> 
> Of course I'll be using the other sound isolation methods as well, but people seem to love this roxul safe n sound stuff (and the cotton stuff) for sound barrier applications.



Besides other material, i use the roxul for some bass traps and like it. The traps seem to do the job, at least for my ears. I don't have any room caliberation device such as omni mic or rew just plain 60 year old ears. I really should get one.


----------



## nathan_h




> Quote:
> Originally Posted by *dormie1360* /forum/post/21596448
> 
> 
> I see the term "small" and "large" acoustical spaces/rooms frequently used. Is there a ballpark ft/3 range when talking about small vs large?
> 
> 
> John



Concert Hall = large

Anything in a home = small


The one paper I have seen that defines it said a small acoustic space is anything under 3,800 square feet and oddly didn't define the ceiling height. (Assuming 8 foot ceilings that's almost 30k cubic feet -- of course that would be a strange feeling room -- ie, any room of 3800 square feet is almost sure to have a ceiling higher than 8 feet -- which means the cubic volume is even larger.)


----------



## dormie1360

Thanks. I'm about 3600 ft/3 with 8.5 ceilings.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *neo95gt* /forum/post/21596229
> 
> 
> Does anyone in here have real world experience with fiberglass vs. roxul? I know most people around these parts are of the opinion that roxul is just not worth it....and the stats back it up. However, the people that I do know that used it (contractors and friends) say that it is worth it and there is a noticeable difference between the two. Any thoughts?
> 
> 
> Of course I'll be using the other sound isolation methods as well, but people seem to love this roxul safe n sound stuff (and the cotton stuff) for sound barrier applications.



This thread is focused on acoustic treatments (in the case of absorption, fiberglas or other porous materials mounted in the room, not inside the walls behind drywall), whereas I believe your question is about soundproofing (fiberglas or mineral wool inside the walls behind drywall). You might have better luck posting a separate question, where you can get replies from experts on soundproofing / theater construction (Ted White, Dennis Erskine).


----------



## neo95gt




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21596983
> 
> 
> This thread is focused on acoustic treatments (in the case of absorption, fiberglas or other porous materials mounted in the room, not inside the walls behind drywall), whereas I believe your question is about soundproofing (fiberglas or mineral wool inside the walls behind drywall). You might have better luck posting a separate question, where you can get replies from experts on soundproofing / theater construction (Ted White, Dennis Erskine).



whoops, thanks


----------



## nathan_h




> Quote:
> Originally Posted by *dormie1360* /forum/post/21596933
> 
> 
> Thanks. I'm about 3600 ft/3 with 8.5 ceilings.



Yes, anything in a domestic setting is gonna be a "small room" in terms of acoustics. In your case, make your room ten times as big and you are getting our of the small room space. But that'd be one room that is larger than even a McMansion


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> 
> The distinction between a Large Acoustic Space (LAS) and a Small Acoustical Space (SAS) is not arbitrary.
> 
> 
> In fact it has a mathematical definition developed by Dr. Manfred Schroeder with important ramifications as it defines limits whereby large acoustical space acoustical principles - as it sets limitations on those generalizations that most encounter in standard textbooks. The understanding of this important distinction was also pioneered by the principles of Bolt, Beranek and Newman.
> 
> 
> The common generalizations that most are familiar have significant limits in a small acoustical space - in many cases not having any validity and requiring the use of a significantly modified subset of acoustical rules.
> 
> 
> Relating this concept to the environment that folks are concerned with here - namely the Small Acoustical Space (SAS), , one can re-write what was originally presented in terms of the "large room frequency", F sub L, to solve for the volume that delineates a SAS. Note that F sub L is not a fixed rigid value, but rather it denotes the transition region, much like the Schroeder critical frequency, Fc, that delineates the distinction between modal and specular behavior regions.
> 
> 
> Fundamental to the distinction is the ability of a Large Acoustical Space, unlike the SAS to support a statistically diffuse reverberant sound field. This ability is frequency dependent, with increasingly larger volumes required to support reverberant sound fields at lower frequencies.
> 
> 
> Thus, using the critical frequencies for the various uses, one can determine the minimum volume required for LAS acoustical principles to apply, and conversely, the limits at which SAS acoustical rules apply.
> 
> 
> The frequency extent required for speech support, 80 Hz, requires a volume of ~35, 313 ft^3 to transition into a LAS.
> 
> 
> For music extending to 30 Hz, the required volume becomes ~251,116 ft^3, and
> 
> for music extending to 20 Hz, the required volume becomes ~565,000 ft^3.
> 
> 
> Put another way, think that for a room simply supporting speech at 80 Hz, with 8 foot ceiling, the room itself must be larger than ~4375 ft^2! ...Larger than most large houses! And for music to 20 Hz, a room with 8 foot ceiling must be a minimum of ~70,625 ft^2 or almost 18 - 4,000 ft^2 houses!!!!
> 
> 
> As should be rather obvious, NO one here is coming close to dealing with a LAS. And it is important to note the distinction and the very critical limitations and necessary differences when one attempts to translate what they see at a LAS theater to their SAS home listening room!
> 
> 
> And thus, no one should be employing statistical math models and reverberant sound field calculations in their SAS. Rather than homogeneous reverberant soundfields, one is dealing with a regionally variant mix of localized modal behavior as well as locally variable specular behavior requiring localized measurements and analysis with such tools as the waterfall/cumulative spectral decay (CSD) for modal behavior and the Envelope Time Curve (ETC) response for specular behavior.
> 
> 
> Acknowledging the distinction between the two models is critical to the application of the proper acoustical rules that govern such spaces. And the acknowledgment of this distinction is one of the critical developments that define the quantum leap in acoustical understanding that has been ushered in by the introduction of time domain measurements over the past ~40 years.



Thanks! That is the Wikipedia quality summary. Awesome.


----------



## pepar

thanks dragonfyr.


----------



## seigneur_rayden

I need an advice on what I should do.

I currently have a 2" X 2 x 4 panel (JM814) straddled in the back corners of the room on the floor for bass traps.


I just acquired 2 4" x 2 x 4 mineral wool panels that I want to use for bass traps.


Should I


1. Add these 4" in front or behind the 2" panels I already have to make them 6"?


or


2. Should I put them on top or below the 2" panels so that the area covered will be floor to ceiling?


BTW, I plan to fill the space behind the panels that are on the floor with fluffy insulation put inside a plastic bag.


Thanks for the help.


----------



## dormie1360




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> thanks dragonfyr.



+1. Thanks.


----------



## myfipie




> Quote:
> 1. Add these 4" in front or behind the 2" panels I already have to make them 6"?





or


> Quote:
> 2. Should I put them on top or below the 2" panels so that the area covered will be floor to ceiling?





> Quote:
> BTW, I plan to fill the space behind the panels that are on the floor with fluffy insulation put inside a plastic bag.



If you plan on filling behind the 2" panels then I would not put the 4" panels in front them. Instead straddle other areas of the room. FYI 2" alone straddling the corner is not enough and make sure the 4" panels (and the 2" panels) do not have any kind of solid backing on them. If they do then they will not work.


Thanks for the help.


----------



## seigneur_rayden




> Quote:
> Originally Posted by *myfipie* /forum/post/21615060
> 
> 
> or
> 
> 
> 
> 
> 
> If you plan on filling behind the 2" panels then I would not put the 4" panels in front them. Instead straddle other areas of the room. FYI 2" alone straddling the corner is not enough and make sure the 4" panels (and the 2" panels) do not have any kind of solid backing on them. If they do then they will not work.
> 
> 
> Thanks for the help.



Thanks Myfipie. I appreciate that. They don't have any backing. I will do like you said.


----------



## warlord260

I live in kent wa.

I have bass traps, and framed panels. Free to anyone that wants them.

PM me.


----------



## simon_templar_32




> Quote:
> Originally Posted by *warlord260* /forum/post/21616929
> 
> 
> I live in kent wa.
> 
> I have bass traps, and framed panels. Free to anyone that wants them.
> 
> PM me.



PM sent.


----------



## nezff




> Quote:
> Originally Posted by *localhost127* /forum/post/0



That's what the article you linked stated. Cellulose or ground up newspaper is bad persay but metal slag or rock wool isn't.


----------



## smakovits

Just curious about the difference and benefit of doing super chunk in a corner vs just hanging a panel.


I am sure it has been discussed before, but I thought to start a fresh discussion on the matter.


----------



## pepar

Been here ?


----------



## nezff

The conversation was about safety and not everything you just wrote which leaves me baffled why you wrote it.


----------



## nezff




> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> 
> LOL!
> 
> 
> You need to go back and read the thread!



The one where I mentioned I went with greener material other than fiberglass and he linked me to a article about the safety of rock wool, fiberglass and cellulose? Never mind.


----------



## nezff

What studies are you basing your statement that newspaper or cotton is more dangerous than fiberglass when enclosed of course in a fabric?


----------



## aaron3421




> Quote:
> Originally Posted by *nezff* /forum/post/21629925
> 
> 
> What studies are you basing your statement that newspaper or cotton is more dangerous than fiberglass when enclosed of course in a fabric?



There was no such statement made. Please cite.


Maybe you added on the part about being enclosed?


----------



## pepar

dragonfyr - what is your "day gig?"


----------



## Al Sherwood




> Quote:
> Originally Posted by *pepar* /forum/post/21635437
> 
> 
> dragonfyr - what is your "day gig?"



With a post like he provided, either a Occupational Health and Safety dude or excellant "Google Researcher"


----------



## cavchameleon

Dragonfyr,


Thanks for the info - very interesting. I did make my acoustical treatments with cotton based material due to the 'non-itchy' nature, but still made them outdoors as they are still dangerous fibers to inhale as you noted (I have a 5yo son, so don't want him to inhale the fibers). Just as a side note, my grandfather died from sever emphysema due to long exposure to cotton fiber inhalation. So I agree, all materials, including natural, have to be handled with care as to reduce any type of fiber inhalation.


----------



## ivanhoek

I had a very difficult time getting my corner acoustic foam (auralex lenrd) to stick.. the problem I had was that at certain points, the freaking corners weren't "square" , so the things wouldn't sit flush and therefore the glue wouldn't bond.


Ouch.. after spending quite a while and TONS of glue , and making my walls look like crap (I hope I never have to take these down, on one corner I even tore up the drywall enough to see the brown backing), I ended up simply nailing the things down , one nail per corner.. seems to work well, but not sure if there's any detriment to this type of attachment.


What does everyone do? Attach them to backing boards? Glue, glue, and more glue?


----------



## PoweredPro

Ivan,

I've seen people use really long straight pins on the out side corners. Also, because I'm an Auralex dealer - I'm wondering are you using the tube glue or spray adhesive?


Also - did you try the temp tabs in your setup?


Also, if anyone here needs a recommendation on placement of Auralex product in their space please PM me.


----------



## ivanhoek




> Quote:
> Originally Posted by *PoweredPro* /forum/post/21650364
> 
> 
> Ivan,
> 
> I've seen people use really long straight pins on the out side corners. Also, because I'm an Auralex dealer - I'm wondering are you using the tube glue or spray adhesive?
> 
> 
> Also - did you try the temp tabs in your setup?
> 
> 
> Also, if anyone here needs a recommendation on placement of Auralex product in their space please PM me.



Essentially, that's what I ended up doing.. the nails are thin and basically function like long pins. I can even reposition them slightly with little force.


Hopefully that will hold and not damage anything







Who knows, maybe the glue has cured and adhered by now. I won't even try to find out though.


Got them to stay up? Leave them alone..


PS. I was using Loctite power grab caulk. Couldn't get the Auralex glue from Amazon on a reasonable delivery time. (earliest was the 20th) This glue I used says it's safe for foam.. we'll see.


----------



## Eric2000




> Quote:
> Originally Posted by *localhost127* /forum/post/21510513
> 
> 
> ... thus, we generally apply a reflective membrane to the corner bass traps such that some mid-HF specular energy is reflective to preserve energy within the room. you can use 6mil plastic to wrap your corner bass traps in ... as bass traps do not need acoustically transparent fabric like the broadband panels do.



I'm relatively new here and have been reading through the most recent pages of this thread - what a great source of information!


I'm in the planning stage creating my corner bass traps for my theater (see signature link) and have a question about the "reflective" warp for corner traps. My wall-hanging panels were covered with a breathable curtain material that I picked up from WalMart and they seem to work quite well. For the corner traps, would it be appropriate to use a "blackout" drape, or similar lined curtain? Or should I track down some 6mil plastic (not sure where I would find it in relatively small quantities)?


Thanks!


----------



## FOH

Eric,


Welcome! We've interacted over at the Cult,..good to see you've found this treasure trove of info. Where in your room will you be adding the bass trapping? If it's front wall/corner, tricky requirements wrt addressing SBIR/boundary interaction, yet retaining whatever dipole rearward energy characteristics that you want to maintain. I've not experimented much w/dipoles, and their interaction w/the front wall,...however I know it's critical.


Also, I'm not sure of the details above your ceiling, but you've likely got quite the potential for significant LF trapping/damping above the ceiling. You've got bass trap potential across all 12 interior corners.


btw; your room is approx the same as mine, ie mine @ 25'x13'x8'.



Good luck and again,..welcome


----------



## Eric2000

Hi Foh,


Thought I recognized your moniker as I was reading back through this thread. The bass traps will go in the back of the room in both of the back corners - floor to ceiling. On my theater page, if you click the picture of my theater it goes to a page where you can see a front and rear panorama of my room.


I was going to build 24x24x36 stackable "superchunk" triangles in each corner. I'll make a ~4ft tall triangle trap and stack a ~3ft triangle trap on top of that and fill them both with triangles of R-19 stacked up. I was wondering about adding 6mil plastic to the front of it (found some at McMaster) or just using a heavy light-blocking drape to wrap the whole thing. I don't know how comparable these two items would be...


I was also thinking about getting some Roxul or fiberglass to put in the space between the ceiling tiles and the bottom of the floor joists across the entire back of the theater. The "dart" tiles in the middle of the room (strange triangle looking relief to them) each have one layer of 1/2 regular drywall just resting on top of them to keep them from rattling around from the huge sub. The perimeter tiles are different because they needed to be cut. The material that the tiles are made from is relatively thin and is very lightweight. It is possible that just filling the 12" or so above them will make a nice bass trap...


I'll have to do some sound measuring for sure.


Eric


----------



## Eric2000

Thanks, dragonfyr! I'll pick up some plastic from Walmart, then. Since you indicate that up to 1/8" MDF can be used as well, this makes me think that space in the back of the room above the plastic ceiling tiles will also work well as a bass trap. Overall, then, I'll be able to line both back corners from floor to ceiling AND the entire ceiling/wall edge as well!


One more noob question (sorry if this was addressed earlier - I haven't made it through the entire thread): Does the plastic for the corner bass trap only go on the front exposed edge of the triangle trap? Or, do you wrap all three sides in plastic?


Thanks!


----------



## Eric2000

Thanks for the additional details! I'll start with making movable traps in the rear of the room. One of the corners has a door that I need to use from time to time, thus portability is a key factor here. Since I imagine it would be difficult to move a single trap that went floor to ceiling, I figure I'll make two and stack them one on top of the other.


I was going to make a 3D triangle: a wood plate on top and bottom and threaded rod to connect them. After I stack one or two layers of fluffy insulation, I was going to make a "web" of 24ga wire I have laying around to keep the stack from sagging over time (same as the orchard netting). I'll just wrap it around the threaded rod and this will hold up the next layer. I'll attach the front plastic and then wrap the whole thing in fabric (thanks for the tip on flame retardant!). When it's done, all that you will see is a giant "sandwich" with wooden top and bottom boards and the fabric in the middle. Should look pretty clean and neat when its done.


Due to the layout of my room and speaker/lighting positions, I'm not sure how easily I can add traps to the front corners. I'll have to see how much improvement I get from the traps in the rear of the room.


My original REW reading (with no EQ) looked something like this (ignore the scale on the left side- I didn't have things properly set up yet). My current response curve looks much better, but I'd like to improve things without using so many filters and such large dB corrections.











Below is my current response curve, but it takes a lot of EQ to get there. The added EQ makes the BFD clip earlier than I would like, makes it necessary to turn down the LFE channel out from my preamp (to something like -13dB), and makes me run my EP4000 amp at full tilt.











I'm hoping bass traps will allow me to get better response without 1) needing some much EQ, 2) needing to turn the LFE out channel down so far, and 3) needing to run the amp at its max gain.


----------



## localhost127

you should also be generating the waterfall plot to view LF decay times (within the modal region).


----------



## kromkamp

I want to throw out a random question. How much resistance bass trapping do you think is required to tame a +10dB peak at 50Hz? By that I mean how thick and how much square footage. Is it even possible? Ignore for the moment that such a trap may (or may not) over damp other frequency regions.


Obviously this is a question based on my own room, but I'm curious what the opinions would be in a general way. I suspect the answer is that no amount of trapping would "solve" a room peak of that magnitude and frequency center.


----------



## Dan_HT_CO

I'm pretty sure the HT room that I'm in the process of framing is going to have serious dead spots due to low freq standing waves. Dim 15'WX18'LX8'H.

I'm assuming bass traps are the best solution?


This is going to be a very nice theater trimmed in custom wood etc. etc.. I'm wondering if it is possible to have a built-in bass traps in the corners that can be hidden - or at least be inconspicuous. I'm not trying to have an acoustically perfect room, but I want it to be very good - clear dialog, respectable dynamic range yada yada yada


It is in a basement and the 2X4 (16 o.c.) framing is set away from the concrete walls by 2. I'm marginally concerned about sound isolation so I plan to fill all cavities with fiberglass or mineral wool and use 2 layers of ½ drywall with green glue between on walls and ceiling.


I've attached a sketch of the concept I was considering. Will this work or is it way off base? You can see that I'm basically asking if I can use the last stud cavity in each side of a corner as a bass trap. If I do an insulation/MLV/air gap/OC704/acoustic fabric build-up will it work? The end result would be flush with the finished drywall and the fabric would be the same color as the wall paint so it would be very discreet.


Again, this is just about trying to minimize the low freq. standing waves to a point that is very good, not perfect. Please don't asking me about what freq range I'm trying to eliminate - if I knew that, I would not post this. Also, if you suggest that I hire a pro, you're too late; my wife beat you to that one.

Attachment 237548


----------



## craig john




> Quote:
> Originally Posted by *Al Sherwood* /forum/post/21639303
> 
> 
> With a post like he provided, either a Occupational Health and Safety dude or excellant "Google Researcher"



Or a self-admitted "blatant plagiarizer":

http://www.gearslutz.com/board/bass-...rs-review.html 


He didn't post his source. However, localhost did a few pages back:

http://www.avsforum.com/avs-vb/showt...9#post21589699 


Craig


----------



## dragonfyr




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21634659
> 
> 
> .....
> 
> 
> And below are a few studies of which I am blatantly lifting from another report on the subject.
> 
> ....
> 
> 
> The following is a short (and by no means exhaustive) list of a few blatantly plagiarized sources of studies and their synopsis without proper attribution (as I have a copy of the doc, but I do not have easy access to the source...sorry):
> 
> ....



Amazing, so the news is that someone FINALLY _actually read_ the post and notices _THAT_ aspect of its content that was _explicitly stated_ no fewer than TWO times??


Congrats!


You can't put anything over on this crowd even when you PLAINLY and REPEATEDLY announce what you are doing!


Now I wonder if anyone will actually bother to read it for the actual point of the post!


The irony is that I do not work for OSHA, but my credentials in acoustical physics _far exceed_ the erroneously posited background in material safety! But that fact is sure to simply cause confusion on this site...


----------



## craig john

Did you miss the words "self-admitted"? BTW, I read it when localhost posted the link. That's why I recognized the SELF-ADMITTED plagierism.


----------



## Dennis Erskine

A small elaboration on Dragonfyr's point about high mass boundaries for modal distribution and lower mass interior boundaries for a better specular environment:


1. In non-sound isolated residential basement rooms, it is not unusual to see modal response more indicative of the foundation walls rather than interior room dimensions. That is not necessarily a bad thing; but, does call for acoustic measurements before making gallant attempts at bass trapping.


2. In the typical residential environment where sound isolation is desired, physical constraints and sound isolation requirements can combine to make the high mass/lower mass approach challenging; but not impossible. I've pulled a couple of examples as nothing more than food for thought.


In the end, you will have modal response issues to solve and the combination of approaches selected should be mindful they don't "suck the life" out of the room.

 

Example2.pdf 80.7529296875k . file


----------



## dragonfyr




> Quote:
> Originally Posted by *craig john* /forum/post/21662905
> 
> 
> Did you miss the words "self-admitted"? BTW, I read it when localhost posted the link. That's why I recognized the SELF-ADMITTED plagierism.



Again, the irony is that it was NOT actually "plagiarism" at all! That term was used as hyperbole.


As, per plagiarism.org :

_"According to the Merriam-Webster Online Dictionary, to "plagiarize" means


* to steal and pass off (the ideas or words of another) as one's own

* to use (another's production) without crediting the source

* to commit literary theft

* to present as new and original an idea or product derived from an existing source."_


I did NONE of the above.


The source was dully credited and acknowledged. I simply mentioned that I did not have the URL or author's information for the source at my disposal. I only had an archival copy of the document - which was indeed credited however inspecifically and it was certainly not passed off as my own!


So while I may use the label "plagiarism" self-referentially in a tongue in cheek fashion in the form of hyperbole, others might instead simply mention that I did indeed _accurately_ reference the material as another's contribution.


I liberally use litote, hyperbole and self-deprecating humor. But I am a bit more sensitive when others repeat it out of context and represent my actions as the literal embodiment of that which was originally an exaggeration.


----------



## pepar




> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> But *I am a bit more sensitive* when others repeat it out of context and represent my actions as the literal embodiment of that which was originally an exaggeration.



Hmmm, maybe that's what needs work so when your chain is yanked you can ignore the yanker.










Your posts are very interesting and informative even if I don't completely grasp the scientific roots. And even knowing what to cut and paste from other posts requires an understanding of the subject matter. Besides, This is not an academic environment and you are not here to publish your works, so "gathering" from other sources copacetic. IMO.










Jeff


----------



## kromkamp

Thanks for the reply. There's a lot of information to digest and I want to get to all of it in time. However, if you don't mind let me focus on my original question:



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21661508
> 
> 
> Hmmm.
> 
> 
> The problem is MUCH more complex than that.
> 
> 
> First, using velocity based porous absorption to damp LF energy is _extremely_ inefficient.
> 
> 
> You see, porous absorbers are near useless when placed at low velocity regions near boundaries where the velocity goes to zero. Conversely, porous velocity based absorption is maximally effective at the quarter wavelength where the velocity is maximal.
> 
> 
> Just considering that a 50 Hz wavelength is ~22.5 feet long, the quarter wavelength spacing where velocity is greatest is *5.6feet* from a boundary! It is there that a porous absorber featuring an optimal acoustical impedance would be ideally placed for maximum effectiveness at 50 Hz. (And remember that here we commonly hear the response that a 2" thick panel is 'prohibitive'!!!)... This should also hammer home the fact that porous 'panels' applied to massive boundaries, however fancily conceived, are NOT significantly effective for LF modal control.
> 
> 
> In fact, to put things into perspective, that is why simply for broadband panels, whereby that to which we are actually referring is NOT LF absorption but absorption sufficient simply to control specular behavior ABOVE the modal frequencies from ~300-400 Hz and up, require a _minimum_ of the appropriate 4 inch thick porous material spaced 4 inches from the boundary - effectively moving the absorptive surface 8 inches from the boundary! And those are NOT LF bass traps! But ironically they are generally far more substantial than most imagine being sufficient for more demanding modal control!



I want to focus on velocity trapping for now, simply because I agree with you when you say the design and construction of pressure based trapping is *very* tricky to get right. Indeed, I have attempted it several times in the past with virtually zero success.


So I understand the theory behind the 1/4 wave distance, but I would counter-submit two other pieces of information:


- Just because that is the placement for maximum benefit, does not mean it's the minimum placement required to have some effect, right?


- for example if you look at the absorption coefficients for 2" materials, they are always at least somewhat efficient down to 125Hz (.3-.4) and there are engineered products such as the Quest products that are even better still.


Obviously its also dangerous to look at 125Hz performance and extrapolate to an octave lower! But even if a product was only 5% efficient in this frequency range couldn't you be successful if you had enough of it? And if you put some kind of thin membrane in front to reflect the highs you would not be in danger of overdamping these frequencies.


Further, my question was not meant to restrict 2" thickness - what about 8"? 12"? 16"? This could readily be accomplished behind a screen wall for example.


Thanks


----------



## nathan_h

I got a calibrated mic from Dayton, hooked it up via my pre-amp, and ran some REW sweeps.... and realized I don't quite know how to interpret these charts.


Here are the stereo mains, run full range, measured from the listening position.


I know room correction could improve this, but I'm curious to see what I can without that. I have 4inch fiberglass at the first reflection points on walls, ceilings and 6 inch of fiberglass 2 foot tall panels all across one floor/wall "corner".


----------



## kromkamp

dragonfyr,


So lets say I were to put 48 square feet (8' wide x 6' high) of 16" thick fiberglass behind my screen, spaced another 16" from the back wall - do you think that alone could do some real damage to a large 50Hz peak?


I have, in the past in another room, attempted some floor-to-ceiling superchunks in all 4 corners similar to what you describe (2' along each wall) and it hardly seemed to make a difference from a measurement point of view.


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/21664464
> 
> 
> I got a calibrated mic from Dayton, hooked it up via my pre-amp, and ran some REW sweeps.... and realized I don't quite know how to interpret these charts.
> 
> 
> Here are the stereo mains, run full range, measured from the listening position.
> 
> 
> I know room correction could improve this, but I'm curious to see what I can without that. I have 4inch fiberglass at the first reflection points on walls, ceilings and 6 inch of fiberglass 2 foot tall panels all across one floor/wall "corner".



I am not an acoustician, nor did I stay at a ...


Other than some stuff very low, your decay time looks very short. Does your room sound dead? My decay times are a little longer than yours, and I am looking at replacing absorption with diffusion.


----------



## localhost127




> Quote:
> Originally Posted by *nathan_h* /forum/post/21664464
> 
> 
> I got a calibrated mic from Dayton, hooked it up via my pre-amp, and ran some REW sweeps.... and realized I don't quite know how to interpret these charts.
> 
> 
> Here are the stereo mains, run full range, measured from the listening position.
> 
> 
> I know room correction could improve this, but I'm curious to see what I can without that. I have 4inch fiberglass at the first reflection points on walls, ceilings and 6 inch of fiberglass 2 foot tall panels all across one floor/wall "corner".



- measure 1 source (speaker) at a time

- [modal region] - generate waterfall plot 0-300hz to see LF frequency response + LF decay times ("modal ringing")

- [specular region] - generate Envelope Time Curve response for each speaker to identify early arriving high-gain indirect specular reflections

- RT60 times are irrelevant in small acoustical spaces (no appreciable reverberation exists)


----------



## nathan_h

Is there an easy way to tell REW to send a test tone to one speaker at a time? Right now, I have only figured out how to send a stereo signal... meaning I have to swap wires for each speaker...


----------



## nathan_h




> Quote:
> Originally Posted by *pepar* /forum/post/21664776
> 
> 
> I am not an acoustician, nor did I stay at a ...
> 
> 
> Other than some stuff very low, your decay time looks very short. Does your room sound dead? My decay times are a little longer than yours, and I am looking at replacing absorption with diffusion.



Not dead, but I too have wondered about diffusion and have some panels I will eventually try out.


----------



## pepar

I just bought 6 24"x24"x7" Skylines and plan on replacing my rear wall absorption. I will try to do some before/after measurements.


----------



## kromkamp




> Quote:
> Originally Posted by *nathan_h* /forum/post/21665751
> 
> 
> Is there an easy way to tell REW to send a test tone to one speaker at a time? Right now, I have only figured out how to send a stereo signal... meaning I have to swap wires for each speaker...



It can be done if your computer has an HDMI output - you can use ASIO4ALL drivers and select which HDMI channel to output to in the Preferences section of REW.


Here is a thread from the HTS forum where I was shown how to do it:

http://www.hometheatershack.com/foru...surrounds.html


----------



## Eyleron

In measuring only the two front speakers, I feel that something critical is missing from the analysis: the center channel.


We keep saying the center is so important for home theater, where majority of on-screen voices, music, effects come from. Not knowing how it's doing wth crossover, eq, modal responses, Envelope Time Curve, etc. seems to be missing an important part!


I say center "channel" because for those with a phantom center, they should look at how a mono signal is performing, which is at greatest risk for comb filtering / modal peaks & valleys by virtue of sending the same signal to two speakers.


Thoughts?









> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> Is there an easy way to tell REW to send a test tone to one speaker at a time? Right now, I have only figured out how to send a stereo signal... meaning I have to swap wires for each speaker...


----------



## kromkamp

Thanks dragonfyr. I think I'm going to give it a try - its pretty cheap to buy a couple bags of insulation and pretty easy to make up some faced frames.


Regarding pressure treatments, Dennis has actually given me plans for one, but I want to explore whats possible with velocity treatments first because of the relative ease of design and construction.


I want to return to your original reply and this comment:



> Quote:
> Combine that with the fact that EQ as a LF tool should NOT be used to attenuate more than ~3 dB of a peak, and you can see the obstacles with which one is faced. (Anything more and I can pretty much guarantees a severely 'out of whack' gain structure that imposes far more issues on the reproduction of sound than does the modal issues they are trying to address! ...Especially given the constraints of consumer level amplification compared to most pro level amplification with its substantially increased duty cycles... )



How does an EQ'd signal look any different to the amplifier? Assuming the source signal of course could already be of some arbitrary frequency response, and already contains all manner of studio processing.


I would say that if you restrict EQ to 3dB there's no point - you can't really hear that little difference.


Thanks!


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21668010
> 
> 
> Regarding pressure treatments,...


 http://www.amazon.com/Acoustic-Absor...dp/0415471745/


----------



## nathan_h




> Quote:
> Originally Posted by *kromkamp* /forum/post/21666136
> 
> 
> It can be done if your computer has an HDMI output - you can use ASIO4ALL drivers and select which HDMI channel to output to in the Preferences section of REW.
> 
> 
> Here is a thread from the HTS forum where I was shown how to do it:
> 
> http://www.hometheatershack.com/foru...surrounds.html



I have HDMI output on the computer and ASIO4ALL available, so I will review that thread and give it a try.


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21666491
> 
> 
> Nathan, we can help you. But help us by posting the REW .mdat file so that we can convolve the frequency response into the various views and window them accordingly.
> 
> 
> And as local observed, we want to drive each source individually with the measurement mic remaining in the EXACT same (reproducible) position for all current and future tests.
> 
> 
> And with treatment in place, its difficult to say what can be done, or what original actual issues exist that require treatment and thus to suggest what needs to be done, as we do not have the untreated baseline response to judge. Untreated measurements would be a wonderful addition if the concept does not scare you too badly... We can then determine the effectiveness of the treatments and suggest any additional measures...
> 
> 
> And seeing as how REW can be used in any number of configured audio topologies it hardly seems work all the effort to attempt to configure it to a specific configuration when it is simply but one possible topology out of many when its easier and quicker to simply manually change the input relative to the device you want to test.



Okay, once I get the measuring of individual speakers working, I'll post the mdat file. I assume the one for the stereo pair isn't as useful, interesting?


----------



## Eyleron

Ha, okay I complicated the issue by mentioning a phantom center. Never mind that.... it's just my trying to include the edge cases.


The point was: the center is extremely important in home theater, and I read here about most people just measuring the stereo fronts, ignoring the speaker they'll be using the most.


I did so too: reading the REW guides I just measured the front two, with and without sub, individually, etc.


But recently I've been assessing the center, and since EQ is always a compromise, I've chosen to sacrifice some smoothness in the stereo fronts in favor of center frequency smoothness and better integration with the sub.


----------



## pepar




> Quote:
> Originally Posted by *Eyleron* /forum/post/21669189
> 
> 
> 
> But recently I've been assessing the center, and since EQ is always a compromise, *I've chosen to sacrifice some smoothness in the stereo fronts in favor of center frequency smoothness and better integration with the sub*.



How did you do that?


----------



## nathan_h

For the record, I measured the stereo fronts first because


1) it was easiest with the default REW setup

2) I listen to two channel music, and when it comes from the turntable, it's without EQ -- so in addition to the usual "get your room as right as possible with treatment before restoring to EQ" wisdom, I want to get my room as right as possible without EQ since sometimes I listen without EQ (but only in stereo).


----------



## pepar

By isolating each (front) speaker, they are able to determine if any first reflection point treatment is needed.


----------



## Eyleron




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> How did you do that?



I didn't like some or the decisions my old crappy MCACC was making for the center, so I made some tweaks.


And I chose a higher crossover so I could EQ more in the BFD, weighting the center more. Width modes affected my two front L and R differently from the C, since they're at different distances from the side walls.


I used DPL-ii music mode with a narrower center-width so that REW would go to the center, since the old receiver doesn't have HDMI.


----------



## Eyleron

Well, I look at the waterfalls, too, which shows the time domain. And as I'm experimenting with bass traps, I'm looking at the center. And the waterfall shows less ringing after EQ and bass traps.


Whether it's frequency-domain (looking at the result of the time domain problems due to modal issues) or anything else, the point is that when I read most people's (for multi-channel, not stereo) description of the channels/speakers they're analysing, they neglect the center. Not to mention the importance in choosing the best locations for listening positions and and subwoofer(s) placement. As you know, a simple modal calculator only goes so far when we're talking about trying to model a real room.


----------



## Eyleron




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670714
> 
> 
> Actually, a cumulative spectral decay is not a time domain response, although it does show a series/sequence of frequency displays.



OK, it involves the added dimension of time, but it's not "time domain." Gotcha.



> Quote:
> And may I politely but firmly make one more fundamental suggestion - move beyond the flatland of the frequency response!
> 
> ...
> 
> Unfortunately all it does is reinforce the need to generate individual measurements in the time domain.



So you read that I'm suggesting that not enough attention is paid to measuring the center, you tell me that I should abandon the "flatland of frequency response" and use the time domain. Then...



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670714
> 
> 
> And in the modal region where the energy is essentially minimum phase, the time domain is not of much use - hence why we use the frequency response and the waterfall display.



Then you say that one should be using the frequency response, aka "flatland."



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670714
> 
> 
> And to expand, you are unfortunately totally ignoring the specular region that specifically determines imaging, localization, intelligibility, and spaciousness and colorization of the direct signal - the very aspects that your explicitly stated concern regarding the center channel (as well as all he rest) - while instead focusing on the modal behavior!



No, I've started playing with the ETC too. I just didn't mention it.


Unless you're saying, "Stop looking at any frequency response or waterfalls for any of the speakers and the sub," then doing so is still part of the analysis, education, and calibration process that people are going to undertake with something like REW.


I've been learning about the comb filtering, learning about the modal problems in the room, learning about the effects of positioning listeners and sound producers in my room, learning about the effects of bass traps, learning about the ETC and trying the blocking method and string method to isolate where reflections are coming from...and I'm sure I'm still leaving something out that you will jump on eg "you're totally ignoring the important..." etc. All the while missing the point, or choosing to address the extraneous and incomplete parts of my point.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670714
> 
> 
> And while modal behavior is important, it is the _wrong_ tool for the job you have specifically identified as the focus of concern.



My focus of concern here is to point out that acoustical analysis and treatment of the center is not given the attention it deserves. Aside from Nathan who was concentrating on stereo music, many home theater enthusiasts read guides and method posts that only include the front-left and front-right and neglect the center. That's all I'm saying. If I left out of this post, "...and I made sure the speakers were facing _towards_ the listeners and not the walls..." it's not because I didn't do that, it's because I just left it out.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670714
> 
> 
> And the answer is NOT to artificially raise the crossover frequency in order to employ more EQ!!!! Above ~80 Hz the response is no longer minimum phase and EQ is NOT correct! This is not an error, but a mistake.



So, to be clear, all filters on the LFE/summed bass channel above 80Hz are a mistake?


In raising the crossover frequency, I also allow higher frequencies to be produced from my subs, where I get a smoother response. Lower the crossover from 100Hz to 80Hz, or 50Hz, and the response was way worse.


I expect a lot of things to change as I employ bass traps that at least fix the upper bass frequencies, as I've already seen it do while positioning bags of fiberglass around. I hope to use less EQ, I hope to be able to reposition the speakers with less regard for modal response and more for imaging. And I'll see what I can get away with using porous absorbers. Luckily, my room's walls aren't too rigid.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670714
> 
> 
> The tool that is appropriate for your stated concern is the ETC response.



My concern in working with REW and the center is inclusive of modal behavior and specular behavior.


----------



## kromkamp

I'm confused - how can the ETC graph be used to identify and correct frequency response issues from 80Hz to, lets say, 300Hz? Surely you are not saying that by treating the identified specular reflections it can correct room response down to these frequencies?


----------



## Eyleron

Thanks for the alignment paper. I actually have looked at group delay when adjusting distances and subwoofers phase in the receiver to get the best response. But it was crude trial and error. The paper show using the impulse response to actually see the delay and adjust accordingly... nice!


----------



## Eyleron




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21670889
> 
> 
> And the center speaker has little to do with modal behavior, and as a result, neither the frequency domain nor the waterfall is the tool that will do the heavy lifting.



I'm not sure if you're saying none of the five or seven main speakers has little to do with modal behavior, or specifically just the center doesn't?


----------



## pepar




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21672113
> 
> 
> Per best practice in a comprehensive approach, EQ is the very LAST step done After ALL of the modal and specular room issues are treated via a variety of methods. And it is then used as sparingly as possible...Unlike the various room correction packages that rely almost solely on it as the first (and essentially only) technique.



This is what I''ve always heard WRT improving a room's sound.


1) Speaker position

2) Listener position

3) Acoustical treatments

4) Electronic correction


Except for subs, though, speaker position is difficult to change as they are usually where they are because of other factors. Listeners are usually where they are because of other factors as well. That brings us to treatments, something that many overlook or eschew because of aesthetics. And that leaves electronic room correction.


I'm not trying to rationalize it, this is reality.


----------



## Eyleron




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21672288
> 
> 
> I sure wish we would figure out what we want to address!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It feels like when we mention specular issues, that the subject shifts to modal issues, and when the topic is modal issues the issue becomes specular.



I believe it is you shifting the topic to something I left out to beat your drum (which I agree is a fantastic drum







).


This is what I started with:



> Quote:
> In measuring only the two front speakers, I feel that something critical is missing from the analysis: the center channel.
> 
> 
> We keep saying the center is so important for home theater, where majority of on-screen voices, music, effects come from. Not knowing how it's doing wth crossover, eq, modal responses, Envelope Time Curve, etc. seems to be missing an important part!
> 
> I say center "channel" because for those with a phantom center, they should look at how a mono signal is performing, which is at greatest risk for comb filtering / modal peaks & valleys by virtue of sending the same signal to two speakers.



I mentioned how I feel the center is ignored, you glom on to the phantom center part. I have highlighted the part in red that contributed little to the point, that I never ever should have mentioned.


Next I say:


> Quote:
> Ha, okay I complicated the issue by mentioning a phantom center. Never mind that.... it's just my trying to include the edge cases.
> 
> The point was: the center is extremely important in home theater, and I read here about most people just measuring the stereo fronts, ignoring the speaker they'll be using the most.
> 
> 
> I did so too: reading the REW guides I just measured the front two, with and without sub, individually, etc.
> 
> 
> But recently I've been assessing the center, and since EQ is always a compromise, I've chosen to sacrifice some smoothness in the stereo fronts in favor of center frequency smoothness and better integration with the sub.



For convenience, I've colored in green the part where I underscore the point that I was focusing on.


When I say I'm measuring with and without the sub, that suggests I'm looking at modal issues, and not specular issues, right? I certainly didn't intend to imply that ETC is lame and specular issues don't exist.


So then you shift us into ETC, implying that someone's making a mistake in looking at modal.


> Quote:
> Simply put, you measure EACH source independently with respect to the time domain.
> 
> 
> And may I politely but firmly make one more fundamental suggestion - move beyond the flatland of the frequency response!...



So now you've launched off about how we should move beyond frequency response to time domain.

When I mention waterfalls, then you say that frequency response and waterfall is appropriate for modal work.


The bouncing around is due to your picking on something that I didn't mention or didn't clarify or use the best language to describe. But continually neglecting to address the point.


I think you're concerned with the main platform of your posts, which is to not try to EQ non-minimum phase problems, to treat modal issues with modal solutions that are best tailored to their behavior (pressure traps for lower bass where porous absorbers fail, etc.), and to treat specular issues with specular solutions. Which is fine, but you keep trying to fit those lessons into responses to my thesis which is that the center speaker shouldn't be ignored.


You finally get around to addressing that by saying that the center isn't part of the modal issues. Which I understand to span the lower frequencies near the crossover of ALL the speakers, and the subwoofer's frequencies.


And then I asked for clarification about your statement, and you reply last with...



> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> The center speaker by virtue that it is a full range speaker typically reproducing voice probably has little impact on the modal frequencies - at least compared to the subwoofer!



Yes, the center channel typically produces voice, but it also contains all sorts of music and effects.


And yes, it doesn't contribute as much to the modal frequencies as does the sub. And neither does the front-left. Or the front-right. Because they're probably crossed over at 80Hz.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> But in any event, it is what it is and will contribute accordingly based upon whatever energy is produced in its bandpass.


*Yep, it'll contribute. So, what were you suggesting when you said that the center doesn't contribute to the modal response? That it doesn't contribute as much as the front left and right because it contains LESS music, and thus we should leave it out?*



> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> ALL of the full range speakers will be individually evaluated with an ETC. And from this the various energy wavelets will be evaluated and high gain anomalous returns will be resolved into their vector paths and points of incidence and the appropriate surgical treatment determined depending upon their function in the overall response model.



Good, we're including the center here. We agree about that, and people are doing themselves a disservice if they neglect it in the ETC measurements.


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21672113
> 
> 
> First, the ETC is not used to correct frequency response issues. It is used to address time domain issues with respect to the superposition of high gain interactive specular signals. By addressing these causal issues the destructive results of superposition are negated and the derivative effects upon the frequency response cease to exist.



Well, aren't you simply describing a different means to the same end? If ETF identifies time domain issues, and by correcting them the frequency response issues "cease to exist", then you are correcting frequency response issues in a manner of speaking. So my question is still the same - if I applied room treatments to eliminate all high gain specular reflection signals, can that successfully eliminate the derivative effects on frequency response even down to 80Hz?



> Quote:
> You might want to read the section in the REW tutorial regarding minimum phase



Here is my Excess Group Delay graph for one speaker one listening location:











Does it mean that, with the possible exception of around ~110Hz, this could be considered minimum phase to almost 300Hz? or at least to that blip around 190Hz?


By the way, the tutorial suggests that that response I see around ~110Hz is probably a room null, but in fact what I have centered around that frequency is a large, wide peak (from around 90Hz to around 130Hz). So is EQ a valid tool for me at these frequencies?



> Quote:
> But the larger issue is that your priority seems to be the reverse of best practice. Per best practice in a comprehensive approach, EQ is the very LAST step done After ALL of the modal and specular room issues are treated via a variety of methods. And it is then used as sparingly as possible...Unlike the various room correction packages that rely almost solely on it as the first (and essentially only) technique.



Not at all! Obviously EQ is a last resort, but I still keep it as a tool in the toolbox. As pepar said, most people are constrained from a design point of view as to where speakers and seats can be. Most people are also contrained from a monetary point of view







when it comes to room treatments.


Cheers


----------



## Eyleron




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21673166
> 
> 
> First, there was an ongoing discussion before you jumped in with stuff about "phantom center channels" (the only thing i could figure was an allusion to the apparent virtual image created by spaced sources) and something about some proposing the omission of speakers when measuring the ETC response.



People "jump in" here all the time. There are usually at least two parallel discussions going on at any given time.


You've never heard the term "phantom center" before? It's pretty common practice around AVS. I was using it as it's commonly used. Yes, that's what I meant, not using a center speaker, but for multi-channel source that contains center channel content. Again, that was a minor part of what I was talking about. And you addressed that, but not the point. I thought of this when I saw Nathan's post, but later he clarified he was dealing with stereo music.


No, I didn't propose the omission of speakers when measuring ETC. Read what I wrote again. I said that people often do omit the center, and I proposed that they should not.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21673166
> 
> 
> Best practices for performing comprehensive acoustical measurements for both modal and specular issues haven't changed significantly in over 25 years that I have been actively doing them...



Right, but I wasn't saying that YOU in particular was doing something wrong. Did you think I was saying, "Hey, acoustic experts, scientific journals, and professional theater designers: you forgot something!" ?


A perfect example of what I'm talking about his here: http://www.avsforum.com/avs-vb/showt...2#post21562732 


> Quote:
> Originally Posted by *ADDUpstate* /forum/post/21562732
> 
> 
> Okay, so I ran my first couple REW measurements, and have played with positions, sub delay (distance), Large/Small, treatments, crossover points, bass/treble trim, subs only, subs and mains, etc. ... The purple line is my L/R alone fullrange. (Set to large with subs off)



He refers to the front-left and front-right speaker as "Mains," suggesting they're the two important speakers. He doesn't get into ETC, but I wouldn't be surprised if that, too, stuck with the front-left-right speakers.


I could find another 1000 examples at AVS and Home Theater Shack. From what I've seen, the MAJORITY of people omit the center. This seems really strange and wrong to me, at least for multi-channel purposes. I think this is borne out of the same old-school mentality that has newbies buying giant floor-standers and a tiny center for home theater. Does anyone ELSE know what I'm talking about? Or am I completely wrong here, and you see most people using REW with their center?


I thought it was worth mentioning and asking about. Sorry to interrupt your flow.


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21675546
> 
> 
> This is like being in a fun house of mirrors - where everyone each interprets what is said as being directly and individually 'aimed' at them!



Welcome to teh internetz











> Quote:
> While the ETC is the response that shows you where and what all the cars whizzing around the track are doing sufficient for us to determine the actual dynamic status of the situation sufficient to make and access modifications as necessary.



So this is the part where I (and I'm sure many others) are having difficulties making the mental leap. I am certainly familiar with ETC response graphing, but my practical experience is limited is using it to identify early (


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21676336
> 
> 
> My first suggestion is to STOP running back to the flatland fixation with the frequency response!
> 
> 
> The fact is that few of you even know the actual baseline response of the speakers you are using anyway, let alone can distinguish between the FR of the source and the FR of the speaker-room system.
> 
> 
> And if you know that the time domain behavior is causal, why then do you need to focus on the derivative perspective?



You can't simply say "ignore frequency response" - that's what we hear! If I listen to my system and its one-note bass, I want that to go away. Full Stop. It may be semantics to say you correct it by solving the time domain issues, but the *symptom* is the frequency response aberration, and I want the symptoms to go away.


Look, I'm buying in to what you are selling - But I still have the same question, what am I supposed to *do* with an ETC graph?


----------



## localhost127




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21675546
> 
> 
> The frequency response is a static snapshot of the derivative pileup caused by many factors of which we have absolutely no insight taken after the accident has occurred - affording us no causal information or means by which to possible modify the behavior to avoid the problem.
> 
> 
> While the ETC is the response that shows you where and what all the cars whizzing around the track are doing sufficient for us to determine the actual dynamic status of the situation sufficient to make and access modifications as necessary.



brilliant - i'll be "borrowing" this analogy if you don't mind !


----------



## kromkamp

Fine - you are telling me there is no spoon








I am not sure yet. I will refrain from using the F word here forward in the interests of preventing further conversational roadblocks.


Nevertheless, how many times do I need to ask (and how much more politely!) : How do I use the ETC curve to identify the time domain psycho-acoustic "unpleasantness" in the room, and how to I use that information to even begin to treat it? Is it as simple as finding all high-gain reflections sub-20ms, treating them with broadband treatment, et voila? I suspect not!


----------



## pepar

Let me use a different analogy ... he wants to know how to fish and you keep telling him, in probably the most elaborate technical terms I've ever seen, that there are fish and the method he's presently using won't catch them.


----------



## kromkamp

dragonfyr,


Here's the problem then. You seem to have a lifetime of information locked up inside of you, but to us you are talking Greek (or Latin, or perhaps just Esperanto). If the only answers are "Go read these three texts, the exam is next week closed book" then you will get almost 0% take-up from anyone here. And I suspect that is what is frustrating you.


The reason why someone like Dennis is highly respected around here is that he will spend the day beating you around the head with concepts you don't understand, and then the next day he will come back and explain those same concepts in a way that is of *practical* value to those of us with real world constraints and only one undergraduate degree










I continue to read your postings to find the nuggets of information I can actually do something with.


Putting aside all that, could you at least comment on whether or not I interpreted my excess phase graph from REW correctly?


Cheers


----------



## kromkamp




> Quote:
> Originally Posted by *pepar* /forum/post/21676699
> 
> 
> Let me use a different analogy ... he wants to know how to fish and you keep telling him, in probably the most elaborate technical terms I've ever seen, that there are fish and the method he's presently using won't catch them.



Yes, precisely. Further, that other people have figured out how to fish, fishing is a known solved problem and has been since the 60's, and you don't really want to catch trout, if you aren't out there catching deep-sea tuna there's really no point


----------



## pepar

Seems like a good time to re-post this -










What measurements do I need to do to determine if I need more SSC corner bass traps? I have this one that I thought was telling me I could use more ...


Single measurement location (at MLP)


----------



## kromkamp

I meant to comment on that before - it strikes me as unusual that your response is that strong down to 16Hz with no sign of a roll-off. I'd be a little skeptical that that measurement is correct?


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21676797
> 
> 
> No, you want a one size fits all specific answer to an amorphous ill formed question with guarantees that the suggestion will function to spec without any incumbent responsibility to actually learn what is happening. _And_ that it will not only address objective standards, bu that it will also satisfy whatever personal subjective preference you prefer.



I don't think I asked for that at all - if there's one thing that makes it difficult to have a conversation here its that you are continually jumping to (IMO erroneous) conclusions about our motivations for asking questions.


You and localhost are very passionate about using ETC curves to solve room problems. I want to know more in a way that is practical and doesn't require me to delve into acoustics textbooks or bust out my own control theory texts (all this talk of poles and zeros - I barely understood it the first time around in school)


I am simply asking for more information about the process, and how to use the tools we have at our disposal.


----------



## pepar




> Quote:
> Originally Posted by *kromkamp* /forum/post/21676794
> 
> 
> I meant to comment on that before - it strikes me as unusual that your response is that strong down to 16Hz with no sign of a roll-off. I'd be a little skeptical that that measurement is correct?



Yes, my REW measurements show it nearly flat to 16Hz and then dropping like a stone below 16Hz. Here is an earlier sweep of the subwoofer with REW, though this is a single pair collocated in the front while the Omnimic graph was with two collocated pair (front/rear) ..











And here's one with the previously maligned Audyssey room correct OFF ... (note and compare the time domain parts of this and the previous graph)


----------



## pepar




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21676797
> 
> 
> 
> And as has happened earlier on this forum, we jump from the simple introduction of a tool to the demand for a fully formed final certified design guaranteed to satisfy all concerns - including the wife who wants no visible treatments or speakers in the room.



I missed those posts; were they deleted?


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21676984
> 
> 
> So, since you now have a hammer, you now want me to tell you, in very simple terms, exactly how to build "a house'.



Not even! I am asking for things like which side of the hammer should I hold, and should I use it to drive nails or screws










We can either talk in generalities or we can talk in specifics. I would be very happy to talk specifics, post REW graphs and mdat files if you like - but I have asked now several times for comment about the excess group delay graph that I posted but you don't seem to want to talk about that.



> Quote:
> And then, I can present a slightly simpler modified template that is both suitable and can be reasonably and practically achieved in almost any room. And in doing the aforementioned we will see how the approach can result in an improvement in imaging, localization, intelligibility, lack of coloration, and, depending upon the nature of the specific room, an increase in the sense of spaciousness. But realize that this will also assume the meeting of certain fundamental criteria such as symmetry, properly constructed walls featuring highly resistive walls, and sufficient space to implement the design. I can also explain, on occasion as the opportunities arise, how various compromises can influence the result as well.



That sounds like great information, as long as you realize the sorts of constraints most people have in working with existing residential spaces. But personally I really want to know more about *my* space, and to do that I want to understand how to interpret ETC graphs.




> Quote:
> And then I will predict, just as has happened _previously_ on _this as well (as another) very forum_, that there will again be a few folks who will then take issue with the approach as it does not necessarily address _their_ or yet _another_ particular and undefined subjective preference (in terms of their preferred acoustical response or 'style of house') or another application, be it a critical listening room, studio, home theater, music practice room, board room, lecture hall, or loading platform of the subway - all of which vary in their response and all of which can employ a variety of subjective variance.



Well of course this will happen - like I said, welcome to the internet! Embrace the chaos


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677401
> 
> 
> That sounds like great information, as long as you realize the sorts of constraints most people have in working with existing residential spaces.



physics, psycho-acoustics, acoustics, etc - aren't going to modify themselves based on your "constraints" wrt residential spaces. that is probably your first step into the understanding of acoustics.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21676753
> 
> 
> What measurements do I need to do to determine if I need more SSC corner bass traps?



why would you assume that "corner" traps are going to cure all of your LF/modal issues? are the other boundaries irrelevant to superposition with the direct signal? why does one assume that LF absorption only takes place in the "corners"? porous absorbers are broadband absorbers. ideally, an absorber should be designed such that it is effective at the trouble (actual MEASURED) frequency. in small spaces, broadband absorption is necessary, but for the more troublesome issues - more fine-tuned 'treatments' will be required (not just in the effectiveness of the treatment itself, but the placement as well!).


----------



## kromkamp




> Quote:
> Originally Posted by *localhost127* /forum/post/21677422
> 
> 
> physics, psycho-acoustics, acoustics, etc - aren't going to modify themselves based on your "constraints" wrt residential spaces. that is probably your first step into the understanding of acoustics.



This entire paragraph is wholly irrelevant to almost all of us here. To those whom it is not irrelevant, they hire somebody to build the room for them.


Don't let the perfect be the enemy of the good.


----------



## pepar




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21677237
> 
> 
> No. Local may know which they are...
> 
> 
> But the past 2.5 years have been dominated by exactly the same calls we now receive (as well as cries from 'a few' lost souls who decried the ETC response even being made available to "non-professionals"
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ), with the results that I would rather not see repeated and am not interested in again partaking. The mechanics are objective. I am not interested in additional debates over the subjective preferences of various flavors of ice cream.



I have to ask - do you have dual degrees in acoustics and drama?











> Quote:
> Can you post the mdat file(s)?



I have not previously saved measurement files, only graphs. I see now that I need to save the former as well so that more analysis can be done.



> Quote:
> Was the sweep a full range sweep, or a band-limited sweep?
> 
> For the record, may I suggest making all sweeps full range. The device itself or post processing widowing can always function to restrict the results if necessary.



The Omnimic graphs are with and without Audyssey (XT 32 w/Pro calibration) room correction. It was mono signal driving L&R analog inputs with bass management, so a 2.1 configuration. I don't recall what the swept frequencies were, but IIRC it was limited to what is displayed.


The REW was subwoofer only swept from 5Hz to 200Hz.



> Quote:
> Is there any EQ applied. or is this a purely 'acoustic' response?
> 
> If EQ is applied, it would be beneficial to rerun the baseline sweeps with it turned off.



One of the Omnimic measurements was with no EQ/correction. The others had whatever I was using at the time; my Audysey versions have advanced over the years.


> Quote:
> Off hand, it looks pretty good. Around 70 Hz there seems hints of a null typical of an 8 foot ceiling, and the null ~140 Hz can be a confluence of both the 2nd harmonic as well as perhaps the coincidence of multiple modal resonances. But unless there is substantial resonance, you look OK



The bouncing around above 150Hz where the mains take over is what I wanted to correct with more traps. Room is nominal 13 x 21 x 8. Here is what's behind my false/screenwall -


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21677467
> 
> 
> why would you assume that "corner" traps are going to cure all of your LF/modal issues? are the other boundaries irrelevant to superposition with the direct signal? why does one assume that LF absorption only takes place in the "corners"? porous absorbers are broadband absorbers. ideally, an absorber should be designed such that it is effective at the trouble (actual MEASURED) frequency. in small spaces, broadband absorption is necessary, but for the more troublesome issues - more fine-tuned 'treatments' will be required (not just in the effectiveness of the treatment itself, but the placement as well!).



I assume nothing.


Design limitations preclude using any treatments for modal interactions other than corner traps. The range reproduced by my multiple subs seems well-behaved. It is the region above that to Schroeder that gets wooly. I have some 2" OC 703 panels at first reflection points, and ill-conceived wall carpet below ear level. I also have six Skylines that I am going to swap for the rear wall absorber.


Jeff


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677491
> 
> *This entire paragraph is wholly irrelevant to almost all of us here.* To those whom it is not irrelevant, they hire somebody to build the room for them.
> 
> 
> Don't let the perfect be the enemy of the good.


so what if it is irrelevant to many of us here - it is simply the truth.

if you think we can modify the behavior of physics/acoustics just because the bulk of us are constrained to residential small acoustical spaces, then there is little left to say here.


it is absolutely astounding the difference in communication between some of the studio forums where many users are absolutely thrilled to engage in such a conversation (to learn and explore) - and this forum where is it endless bickering with very little substance (and more cries for "on size fits all" solutions). this is not a personal statement to anyone, just my own personal observation.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21677541
> 
> 
> I assume nothing.
> 
> 
> Design limitations preclude using any treatments for modal interactions other than corner traps. The range reproduced by my multiple subs seems well-behaved. It is the region above that to Schroeder that gets wooly. I have some 2" OC 703 panels at first reflection points, and ill-conceived wall carpet below ear level.
> 
> Jeff



your statement was - what measurements are needed to determine if you need "more" corner traps. what happens when you run out of corners?



> Quote:
> Originally Posted by *pepar* /forum/post/21677541
> 
> 
> I also have six Skylines that I am going to swap for the rear wall absorber.



why not utilize the skylines in front of the LF rear wall absorbers? (granted seating distance to diffusers are appropriate)


----------



## kromkamp




> Quote:
> Originally Posted by *localhost127* /forum/post/21677627
> 
> 
> it is absolutely astounding the difference in communication between some of the studio forums where many users are absolutely thrilled to engage in such a conversation (to learn and explore) - and this forum where is it endless bickering with very little substance (and more cries for "on size fits all" solutions). this is not a personal statement to anyone, just my own personal observation.



Are you really surprised? Really? Consider the audience for once - here we are all concerned with building a great room to entertain guests and enjoy being in. There is a balance of priorities and ideal sound is only one of them. In a studio there is no such compromise - the *only* goal is sound quality.


I really don't understand why you find this so difficult to grasp.


And for what its worth, I think a lot of people here are willing to put in a lot of legwork (contrary to your belief that everyone wants a "one size fits all" solution) but again there are almost always constraints on whats possible. Is it your conclusion that its not worth it to do *anything* in this case?


The classic example are the so called 2" treatments. You basically say its 8" or its crap. Dennis produces designs subject to this constraint - are you saying his rooms sound like crap?


----------



## pepar




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21677604
> 
> 
> 
> But you and a few others seem determined to generate drama. And very few who are serious to learn about the physics - in fact, specifically and actively stating their desire to avoid having to do exactly that as others demand simple practical 'answers' to overly generalized imagined spaces.
> 
> 
> As far as 'are additional treatments necessary', who knows. Measurements made with tools like Audyssey engaged tell us little and obscure what is happening acoustically. And the excessive use of EQ can _easily_ create such behavioral anomalies in other regions of the passband.



Having a head full of knowledge is not anywhere near being able to actually help people with it. I'm sorry that I don't measure up, but I am tired of being lectured to. So I am going to withdraw my ill-formed request for help.


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21677723
> 
> 
> No. You don't get it. It is not my job to "realize the sorts of limitations most people have".



I hope you don't consider participating here a job - you certainly aren't getting paid for it.


If you don't want to consider the audience that's fine - but then all your effort is likely not to be appreciated and I would recommend you don't bother.



> Quote:
> But one might quickly realize that porous absorption for LF modal issues is neither the only treatment option, nor is it the most effective. And this is precisely a case where a greater understanding of physics quickly affords one more options that, while a bit more complex, are also more effective.



A good case in point - I think many people here realize that porous absorption for LF modal issues is not the most effective. But pressure traps are very difficult to build and even harder to prove you built them right (fixed the right problems rather than making others worse). So they are often discounted. Don't mistake this for ignorance on our part necessarily.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21677645
> 
> 
> your statement was - what measurements are needed to determine if you need "more" corner traps. what happens when you run out of corners?



I have plenty of unused corners.



> Quote:
> why not utilize the skylines in front of the LF rear wall absorbers? (granted seating distance to diffusers are appropriate)



I would like to tweak (and improve) what I already have without tearing everything out and starting from scratch. For now, anyway, the false wall cavity's treatment is staying as it is.


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677715
> 
> 
> Are you really surprised? Really? Consider the audience for once - here we are all concerned with building a great room to entertain guests and enjoy being in. There is a balance of priorities and ideal sound is only one of them. In a studio there is no such compromise - the *only* goal is sound quality.



check the thread title - this is "Acoustical Treatments Master Thread" - not a user's self-created thread based on THEIR room based on THEIR design requirements and THEIR end-response goals.


and the concepts and acoustical models of that of a mixing/mastering studio are directly transferable to that of a critical listening space.


...and in studios there are still compromises, as financials are most certainly a factor.



> Quote:
> Originally Posted by *kromkamp* /forum/post/21677715
> 
> 
> And for what its worth, I think a lot of people here are willing to put in a lot of legwork (contrary to your belief that everyone wants a "one size fits all" solution) but again there are almost always constraints on whats possible. Is it your conclusion that its not worth it to do *anything* in this case?
> 
> 
> The classic example are the so called 2" treatments. You basically say its 8" or its crap. Dennis produces designs subject to this constraint - are you saying his rooms sound like crap?



please quote me where i say 8" or "crap". my statements are with regards to attenuating the broadband specular signal down to the lower specular region OF WHICH with typical speaker designs there will be MORE off-axis energy dispersed of which has LONGER wavelengths of which has MORE inherent energy content. and yet so many wish to "treat" for the HF content with their thin absorbers of which has little energy content and is generally more DIRECTIONAL of which there is LESS energy thrown to the reflection points in the first place!


it was only a few weeks ago you were arguing me with the usefulness of the mirror to identify reflection points (and your insistence of treating "all reflection points" - regardless of their incident gain or time-arrival).


im really curious as to what ground you feel you stand on regarding the discussion of acoustics with such commentary.


and your cute little comment that seems to imply i am making ANY subjective statements regarding Dennis' designs is hogwash and a last ditch effort by yourself to stir up absolute nonsense because you lack any sort of effort to adhere to the focus of the subject re: acoustics.


and to think Pepar claimed it was dragonfyr who likes the drama??


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21677792
> 
> 
> I would like to tweak (and improve) what I already have without tearing everything out and starting from scratch. For now, anyway, the false wall cavity's treatment is staying as it is.



depending on what measured issues you are seeing from the rear wall will dictate whether you still need LF absorption there...


will your skylines attenuate the signal to the same lower frequency cut-off as your absorber? do you need further LF absorption of the rear wall phasor? or do you want to *combine* LF absorption with mid-HF diffusion to provide some energy back into the room?


and why do you wish to use 2D reflection phase grating diffusers vs that of 1D? what was your criteria for making such a decision?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *kromkamp* /forum/post/21666136
> 
> 
> It can be done if your computer has an HDMI output - you can use ASIO4ALL drivers and select which HDMI channel to output to in the Preferences section of REW.
> 
> 
> Here is a thread from the HTS forum where I was shown how to do it:
> 
> http://www.hometheatershack.com/foru...surrounds.html



Thanks kromkamp and nathan_h for this tip, I downloaded the 5.01 beta REW and ASIO4ALL driver last night, and will see if I can get it to work tonight.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21677818
> 
> 
> 
> and why do you wish to use 2D reflection phase grating diffusers vs that of 1D? *what was your criteria for making such a decision?*



A friend didn't need them and sold them to me for $50 each.







If I swapped my front wall/ceiling absorbers for diffusors, I would use QRDs.


----------



## kromkamp




> Quote:
> Originally Posted by *localhost127* /forum/post/21677806
> 
> 
> check the thread title - this is "Acoustical Treatments Master Thread" - not a user's self-created thread based on THEIR room based on THEIR design requirements and THEIR end-response goals.



Check the Forum title - its "Home Entertainment & Theater Builder", not "Studio Builder"



> Quote:
> the concepts and acoustical models of that of a mixing/mastering studio are directly transferable to that of a critical listening space.



The *acoustic* goals are the same, but nothing else - how many mixing studios do you know of with a popcorn machine in them?



> Quote:
> please quote me where i say 8" or "crap".



If you *really* want me to I'm sure I could. Virtually 100% of your forum posts exclusively recommend using 4" treatments spaced 4" from the wall. You do the math.



> Quote:
> it was only a few weeks ago you were arguing me with the usefulness of the mirror to identify reflection points



Yes, as do you here:

http://larchive.avsforum.com/www.avs...9#post21273989 


I agree with what you say at the bottom of that post - no more no less. I never said using a mirror was the be all and end all.



> Quote:
> and your cute little comment that seems to imply i am making ANY subjective statements regarding Dennis' designs is hogwash and a last ditch effort by yourself to stir up absolute nonsense because you lack any sort of effort to adhere to the focus of the subject re: acoustics.
> 
> 
> and to think Pepar claimed it was dragonfyr who likes the drama??



I never said I didn't like drama







but my point is 100% valid - you continually argue that physics does not bend to the will of good aesthetics and practical considerations, and yet Dennis produces designs that do all the time (as I'm sure many other theater designers do). I can't reconcile these two datapoints and I don't think you can either.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21677766
> 
> 
> Having a head full of knowledge is not anywhere near being able to actually help people with it. I'm sorry that I don't measure up, but I am tired of being lectured to. So I am going to withdraw my ill-formed request for help.



actually, the issue is not with dragonfyr but with you yourself. you are unwilling to put forth the effort and presume acoustics is a simple topic. no one is "forcing" you to learn anything, but if you wish to traverse the rabbit hole that is acoustics, you will need to understand the underlying principles, physics, etc -


yes, you're tired of being "lectured to". just like when dragonfyr went through the multi-page commentary regarding the MISCONCEPTION that diffuse or reverberant sound-field exists our rooms, and so many insisted that they did exist.


and what did you have to say after all of that knowledge was presented on a silver platter?

--> http://www.avsforum.com/avs-vb/showt...1#post21284261 


why would anyone continue to assist you with your questions when you act in such a manner.


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677783
> 
> 
> I hope you don't consider participating here a job - you certainly aren't getting paid for it.
> 
> 
> If you don't want to consider the audience that's fine - but then all your effort is likely not to be appreciated and I would recommend you don't bother.



and to think, dragonfyr has basically given you all of the knowledge on a silver platter - you are just too blind by emotion to absorb it.


dragonfyr,

maybe you should start "charging" - do you think people will think your commentary is more credible if there are dollar signs attached to it?




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677783
> 
> 
> A good case in point - I think many people here realize that porous absorption for LF modal issues is not the most effective. But pressure traps are very difficult to build and even harder to prove you built them right (fixed the right problems rather than making others worse). So they are often discounted. Don't mistake this for ignorance on our part necessarily.



no - it's just no one wants to put forth the effort because they *think* it is too difficult. i wonder why all of the "home/bedroom studio" forum users are able to take the challenge, but in this forum it is simply a lost-cause and not even worth the attempt.


----------



## localhost127




> Quote:
> Originally Posted by *pepar* /forum/post/21677858
> 
> 
> A friend didn't need them and sold them to me for $50 each.
> 
> 
> 
> 
> 
> 
> 
> If I swapped my front wall/ceiling absorbers for diffusors, I would use QRDs.



awesome deal on the price.


although i would still prefer PRD over QRD (but my original statement was in reference to 1D vs 2D skyline, not PRD skyline vs QRD)


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677879
> 
> 
> Check the Forum title - its "Home Entertainment & Theater Builder", not "Studio Builder"



this is the acoustical master treatment thread.


again, you wish to discuss anything but acoustics - and you sure do not have any "authority" on the subject.



> Quote:
> Originally Posted by *kromkamp* /forum/post/21677879
> 
> 
> The *acoustic* goals are the same, but nothing else - how many mixing studios do you know of with a popcorn machine in them?



please, detail the "acoustic goals". be specific.




> Quote:
> Originally Posted by *kromkamp* /forum/post/21677879
> 
> 
> If you *really* want me to I'm sure I could. Virtually 100% of your forum posts exclusively recommend using 4" treatments spaced 4" from the wall. You do the math.



yes - i really want you to. please quote me where i say "crap".

and if you actually took the time to understand the lower frequency limits that must be absorbed with regards to specular energy, and how porous insulation "works" or is "most effective", then you too would choose an appropriate GFR/thickness material. but of course, you'll still fail to understand the impact of the speaker response as well as acoustical impedance of boundary - as you have in prior threads. ( http://www.avsforum.com/avs-vb/showthread.php?t=1391430 )


please quote me?


----------



## kromkamp




> Quote:
> Originally Posted by *localhost127* /forum/post/21677917
> 
> 
> no - it's just no one wants to put forth the effort because they *think* it is too difficult. i wonder why all of the "home/bedroom studio" forum users are able to take the challenge, but in this forum it is simply a lost-cause and not even worth the attempt.



Well, as dragonfyr said:



> Quote:
> Unfortunately their design is more complex and an iterative process, as their inclusion in the system has the effect of modifying the system of which they are a part. Thus while they are not out of the reach of the average person, their design and integration is not a trivial process.



More than a little daunting, to be sure. That being said I'm certainly not diametrically opposed to using them.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21677892
> 
> 
> actually, the issue is not with dragonfyr but with you yourself. you are unwilling to put forth the effort and presume acoustics is a simple topic. no one is "forcing" you to learn anything, but if you wish to traverse the rabbit hole that is acoustics, you will need to understand the underlying principles, physics, etc -
> 
> 
> yes, you're tired of being "lectured to". just like when dragonfyr went through the multi-page commentary regarding the MISCONCEPTION that diffuse or reverberant sound-field exists our rooms, and so many insisted that they did exist.



I would suggest that anytime someone feels the need to post a multi-page commentary regarding any misconception, they should take a pill.


Jeff


----------



## kromkamp




> Quote:
> Originally Posted by *localhost127* /forum/post/21677970
> 
> 
> again, you wish to discuss anything but acoustics - and you sure do not have any "authority" on the subject.



Not sure you do either - but I wasn't aware that was a prerequisite here.



> Quote:
> yes - i really want you to. please quote me where i say "crap".



no problem - I doubt you used that actual word but something similar. Should be a fun project for me to do tonight.



> Quote:
> and if you actually took the time to understand the lower frequency limits that must be absorbed with regards to specular energy, and how porous insulation "works" or is "most effective"



You keep saying that as though its not completely obvious that thicker treatments are more effective at lower frequencies - just curious if you don't think I understand that? Because I assure you that I do.


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678064
> 
> 
> no problem - I doubt you used that actual word but something similar. Should be a fun project for me to do tonight.



oh, yes - changing your tone now since i called you out. you're willing to spend your entire evening digging through my commentary searching for the term "crap" and yet you refuse to take a few brief moments to further your knowledge on the relevant subject of acoustics.


this is representative of the prevalent attitude here. well done!





> Quote:
> Originally Posted by *kromkamp* /forum/post/21678064
> 
> 
> You keep saying that as though its not *completely obvious that thicker treatments are more effective at lower frequencies* - just curious if you don't think I understand that? Because I assure you that I do.


*thicker treatments do not necessarily mean more effective absorption at lower frequencies.* this is over-simplification of porous absorption. i assure you you do not understand this based on your commentary.


----------



## kromkamp




> Quote:
> *thicker treatments do not necessarily mean more effective absorption at lower frequencies.* this is over-simplification of porous absorption. i assure you you do not understand this based on your commentary.



Oh good - then it means I won't need to use 4" treatments spaced 4" away from the wall after all! Huzzah!


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678110
> 
> 
> Oh good - then it means I won't need to use 4" treatments spaced 4" away from the wall after all! Huzzah!



precisely - you ignore (or you are completely unaware) of the other factors that dictate a porous absorbers performance, as thickness alone is not the only variable. hence, you'll generally see the recommendation for thickness relative to a specific material (or more accurately, a material with a specific gas flow resistivity value).


----------



## kromkamp

So give me an example of an porous acoustic treatment that absorbs less LF as it gets thicker please.


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678151
> 
> 
> So give me an example of an porous acoustic treatment that absorbs less LF as it gets thicker please.



do you understand what gas-flow-resistivity means? or do you think "thickness" is the absolute variable that determines the performance of any porous insulation. oye.

http://www.whealy.com/acoustics/Porous.html


----------



## kromkamp

Same question. Supply an example please.


----------



## localhost127

there's really no point in going through this exercise with you. you clearly have your mind made up regarding porous absorbers...


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678175
> 
> 
> Same question. Supply an example please.



porous absorber calculator.

OC703 - 16,700rayls/s (although NASA has tested differently).

increase thickness.

observe.


----------



## kromkamp

According to Owens Corning's own specifications, you are wrong. From Bob Gold's site:


703, plain 1" (25mm) on wall 3.0 pcf (48 kg/m3) 0.11 0.28 0.68 0.90 0.93 0.96 0.70

703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00

703, plain 3" (76mm) on wall 3.0 pcf (48 kg/m3) 0.53 1.19 1.21 1.08 1.01 1.04 1.10

703, plain 4" (102mm) on wall 3.0 pcf (48 kg/m3) 0.84 1.24 1.24 1.08 1.00 0.97 1.15

703, plain 6" (152mm) on wall 3.0 pcf (48 kg/m3) 1.19 1.21 1.13 1.05 1.04 1.04


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678236
> 
> 
> According to Owens Corning's own specifications, you are wrong. From Bob Gold's site:
> 
> 
> 703, plain 1" (25mm) on wall 3.0 pcf (48 kg/m3) 0.11 0.28 0.68 0.90 0.93 0.96 0.70
> 
> 703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00
> 
> 703, plain 3" (76mm) on wall 3.0 pcf (48 kg/m3) 0.53 1.19 1.21 1.08 1.01 1.04 1.10
> 
> 703, plain 4" (102mm) on wall 3.0 pcf (48 kg/m3) 0.84 1.24 1.24 1.08 1.00 0.97 1.15
> 
> 703, plain 6" (152mm) on wall 3.0 pcf (48 kg/m3) 1.19 1.21 1.13 1.05 1.04 1.04



why do you stop at 6"? what happens at 30"? 60"? the porous absorber keeps getting thicker, shouldn't it be absorbing lower frequencies more effectively like the blanket statement you made?


the point of this exercise was to attempt to introduce to you the fact that there are more variables than simply "thickness" of a porous absorber.


what do you think happens as you continually increase the thickness of a _porous_ absorber? what happens as GFR increases? what happens if the soundwave can no longer penetrate through the porous holes and thus is no longer converting kinetic energy of the flow into heat? ..and the "absorber" suddenly becomes a "reflector".


again, the exercise will fail because you are utterly ignorant about the complexity of porous absorption and the inherent variables OTHER than thickness.


----------



## localhost127

and revisiting the original statement of which your contention spawned from, you'll notice that the recommendation of 4" absorber w/ 4" air-gap is generally accompanied by a material with GFR or density outlined (eg, this is usually in reference to OC703 (3pcf) or Mineral Wool (4pcf) when giving 4" thickness 4" air-gap recommendation) - as the absorber needs to have a high absorption coefficient based on the lower specular region (250-300hz) as well as taking into considering angle of incidence, speaker radiation pattern, acoustical impedance of boundary, etc.


----------



## kromkamp

Don't know and don't care. Probably at 1000" something else happens again. Its outside the context of the conversation. You are being deliberately obtuse.


Newtonian physics aren't accurate either - but if I ask you what time it is the correct answer is not "depends how fast you are traveling"!


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678323
> 
> 
> Don't know and don't care. Probably at 1000" something else happens again. Its outside the context of the conversation. You are being deliberately obtuse.



welcome to acoustics.


----------



## pepar




> Quote:
> Originally Posted by *kromkamp* /forum/post/21678323
> 
> 
> 
> Newtonian physics aren't accurate either - but if I ask you what time it is the correct answer is not "depends how fast you are traveling"!


----------



## nickbuol

OK. Let me say it. You guys are all WAY more advanced in your knowledge and expertise on this whole subject that most of us. Heck, I get lost in the long posts about how to do some of this stuff, but I DO appreciate your efforts. It just goes to show how passionate you all are about giving the "right" information (whatever that is). I have been following this thread for quite some time, and I get little golden nuggets that I can easily understand and implement and I plan to use them. My room will be better for it, even without the (to me) complex REW graphing and such.


Maybe, someday, I will try to drive down that road...slowly...and with my hazard flashers on... But I am sure that the further I go down the road, the more I will understand where it is I am trying to get to.


So with that, step back and take this guy's "thank you"....


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21678413
> 
> 
> If you knew what you were talking about you would know that you are not comparing two absorbers, but rather a porous absorber on the one hand, and a hybrid binary amplitude diffuser (BAD) that incorporates about 4 inches of absorption behind a diffusive Galois sequence membrane on the surface!





> Quote:
> And simply applying inadequate amounts of absorption (such as the commonly used 2" thick panels you mentioned above) is NOT necessarily better than nothing



I'm doing no such thing. Dennis uses Quest products (well I'm sure not exclusively) which are 2" deep full stop. Are you saying these are not better than nothing?


----------



## Mike Lang

Cool it with the personal comments guys...


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21678638
> 
> 
> We have already explained the issue.
> 
> 
> Heck, even Toole addresses the issue and laments the effective EQing of specular reflections resulting in coloration (in addition to the original issues!).
> 
> 
> If they are using the equivalent of OC700 series semi-rigid fiberglass panels, the problem exists.And the specs they quote assume a diffuse incident soundfield - something that does not exist in a small acoustical space.
> 
> 
> What you choose to live with is your choice.



And I guess the owner of this magnificent theater:

http://www.avsforum.com/avs-vb/showthread.php?t=1373052 


also does not realize that, in fact, his room sounds worse than if no treatments had been applied at all. I hope no one tells him










Cheers


----------



## Elite HTS

My acoustic designer has specified the following for the wall behind my screen :

"Two layers 1" Johns-Manville Coated Insulshield Black or Linacoustic RC (black)

with 3 mil vinyl sheeting between layers."


However I cant find this product anywhere in my area (Vancouver, BC). I looked on the Johns-Mansville website and Rona is one of their dealers, but I called all the local stores and no one has heard of it.


Does anyone know where I can buy this product in the Vancouver area?


----------



## R Harkness

Question about acoustically transparent fabric:


Right now I use dark velvet curtains to pull along my side walls to kill some room reflections. But I want to go further and have the ability to make a "black box" in the room. Therefore I'm augmenting my existing curtains with some black acoustically transparent (e.g. speaker grill material) curtains.


In this picture you can see the room. I pull the curtains along the wall and put thick dark brown velvet covering the entire fireplace wall. The opposite room wall gets the same treatment. However, this leaves uncovered the bright wall past the fireplace toward the windows on each side of the room, (with the surround speakers on them) as well as the entire area behind the sofa.


I want to cover the entire area but I DON'T want to deaden the room any more (if possible). So I'm going to add acoustically transparent curtains to cover those remaining spots, including one big curtain that will pull behind the entire sofa (with cut out for projector light).


Can I presume that adding this much "acoustically transparent" material (again, the type used for speakers) this should have minimal acoustic effects? The point is with the amount of velvet I already use on the walls, along with the live portions of the wall, I get a not-too-dead sound. I just want to make sure that using acoustically transparent material to cover the rest of the walls will still keep some "live" surface area.


Opinions?


Thanks.


----------



## nathan_h




> Quote:
> Originally Posted by *kromkamp* /forum/post/21679070
> 
> 
> And I guess the owner of this magnificent theater:
> 
> http://www.avsforum.com/avs-vb/showthread.php?t=1373052
> 
> 
> also does not realize that, in fact, his room sounds worse than if no treatments had been applied at all. I hope no one tells him
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Cheers



I think Dennis talks about how most of the treatment in there is diffusion.



> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21499901
> 
> 
> ...
> 
> Sucking the life (aka absorption of early -or otherwise- reflections) out of a room is not at all a best, or better, practice. Diffusion and/or diffraction is an alternative.


----------



## kromkamp

I want, if we could, to return to my original question on ETC. you hit the nail on the head here:



> Quote:
> There are also secondary issues of pattern recognition useful in identifying how treatments such as absorption, reflection and diffusion appear in an ETC, either for use in analyzing existing behavior or in evaluating where a particular treatment would be appropriate and useful…in other words, 'how' to employ the tool in order to accomplish a specific well defined goal. But there use is only practical only AFTER a specific acoustical response goal has been specifically defined.



This is exactly what I'm after. Unfortunately I have to answer you with another question: What are the parameters that define a specific acoustical response? If I tell you I want it to sound "good" or "accurate" or "pleasing" that is surely not sufficient. And yet if I tell you it's a home theater then surely there are baseline standards that define that acoustical response goal, no?


----------



## Peter M

As someone who has followed this thread since day one, I'd like to make a few comments. This part of AVS is mostly populated with DIYer's and in the beginning I believe this thread provided us with some good, basic design advice, which could be quite easily put into practice with relatively little expense. Those with a sufficient budget would normally employ a professional to do all the acoustic 'heavy lifting'.


More recently the thread has evolved into a much deeper discussion that I believe very few of us have sufficient time, education or experience to follow, and certain participants just don't seem to understand the audience they're talking to.


I would really like to see the thread return to being a source of practical, achievable advice for the average DIYer, trying to get maximum bang for buck.


Cheers,


----------



## Dennis Erskine

Knauf, Certainteed, Owens-Corning and others manufacture similar products to the J-M *Coated* InsulShield Black. In your application, Elite, the product specified is (a) going behind an "acoustically transparent" screen; and, (b) will be exposed to the living environment. Other than the statistically similar physical properties, you require a product which is (a) a uniform color of black [noting black is not a color]; and, (b) meets local environmental air quality standards for a product exposed to room air.


The Quest products are not simple sheets of OC700 series fiberglass. They are fabricated laminates of a combination of various fiberglass board, vinyl, and backing products with performance characteristics radically different from a simple 1", 2" or 4" off the shelf fiberglass board. The specifications quoted do not *assume* a fully random incident, diffuse sound field. ASTM testing methodologies have defined the conditions under which the specified testing is to be conducted. Until such time as a series of standardized testing methodologies are codified more appropriate to small acoustical spaces, we have to adapt, overcome, and utilize OTJ practical experience to interpret actual, as built expected performance.


The performance and applicability of any given acoustical material (particularly porous materials) cannot be judged independently. Once such a material is applied to any other material (4" fiberglass applied to 1/2" drywall, attached to 22 gauge, 5.5" steel studs 24" O.C. for example), the resultant is not the sum of the materials ... the behavior is that of an entirely different or "third" material if you will. You cannot ignore the impact of the underlying strata in any series of layered materials and their order of occurrence.



> Quote:
> it is not my problem here to solve personal, social, financial, or any other problems that someone may artificially impose upon the issue



None-the-less, personal, social, financial, or any other problems are not "artifical" within the context of the unique individual or specific constraints of any given, individual and specific project. Those "problems" in any given specific project, to the homeowner, are real and must be addressed if only to inform the homeowner, commercial contractor, mix engineer, artist, or studio executive as to how those "problems" or constraints may impact the final result. At some point there must be a convergence of expectations and applied constraints.


----------



## kromkamp

Insulshield is 1.5 pcf density so any similar density product should be a decent substitute.


It sure can be a pain finding these products in Canada sometimes...


----------



## Dennis Erskine




> Quote:
> Insulshield is 1.5 pcf density so any similar density product should be a decent substitute.



Not exactly ... but pretty close. The "coated" part of the J-M product not a pure coating, has a slightly different density and porosity than the straight fiberglass. Let me know what you find locally and I'll check it out for you.


----------



## localhost127




> Quote:
> Originally Posted by *kromkamp* /forum/post/21681129
> 
> 
> Insulshield is 1.5 pcf density so any similar density product should be a decent substitute.



two different porous insulations with identical density can have differing GFR values.


----------



## Eyleron




> Quote:
> Originally Posted by *Peter M* /forum/post/21680022
> 
> 
> This part of AVS is mostly populated with DIYer's and in the beginning I believe this thread provided us with some good, basic design advice, which could be quite easily put into practice with relatively little expense.
> 
> ...
> 
> More recently the thread has evolved into a much deeper discussion that I believe very few of us have sufficient time, education or experience to follow, and certain participants just don't seem to understand the audience they're talking to.



I see some progress being made in:

What is the purpose of this forum/thread?

What are the limitations of the veteran theater buff, the theater DIYer hobbyist, and the newbie? How best to interface with him?

What are the limitations of the acoustician? How best to interface with him?

*Forums & Thread*

I think many of the problems with this thread and forum is what you'd have if you couldn't break out the Sources into separate fora like cable, local hdtv, bluray, etc. Or display devices into LCD, Plasma, Projectors, Expensive Projectors. Or speakers into DIY, subs, etc. Acoustics It's too broad a topic, and it doesn't even have a dedicated forum. There's also "Audio Theory, Setup, & Chat" again, too broad for acoustics.


This particular thread is full of interjections like the one I made earlier, trying to reconcile and emulate designers' methods, bang-for-buck DIY treatments, actual usage of measurement methods, acoustic models, trying to reconcile works like Toole's with other paradigms, and "hey i'm new to this stuff but what do ya guys thing i should do?"


I suggest splitting out theory discussion and help-me threads. And if there are agreed-upon general precepts and critical core concepts, then we need sticky-worthy primers. Until those exist, then the "experts" are in a constant drone of repeating the same forever.

*Real World Theater Application of Acoustics*

I agree with Mr. Erskine; there are compromises and limitations in applying acoustic science to home theaters. If one doesn't deal with that, then you're just reading, writing, or repeating theory textbooks.


This topic(s) is so much more difficult to grasp and address than "what's the best sub?" threads. But there's something to be learned from there. The newbie there thinks there's one end-all solution for subwoofers. The veteran educates that different subs meet different goals and criteria, and ask, "*What are your constraints, what do you want to do?*" Without that starting point, it's all theory, or a tug of war of competing solutions to meet different goals, without addressing the real constraints.


So I can appreciate dragonfyr's frustration when people skip that first step of establishing "what CAN I do? what are the different models and their tradeoffs for me, what are my constraints?"


I thought a great step forward were the threads of a few months ago where the different room models were being discussed and people wanted real application of ETC. - Not sure what happened with that...I last read discussion about which models are most appropriate for stereo music, versus for multi-channel home theater. Here's one of the threads: http://www.avsforum.com/avs-vb/showthread.php?t=1366724 

*Someone needs to write the Room Model Primer*
Main classes of models:

Reflection-Free Zone

Live-End Dead-End

Ambiechoic

...
with some variations within each
primary attributes of each (eg LEDE: acoustically-damped "dead" front, suited more for the soundstage and ambiance to be produced by the source material and multiple speakers, with a more "live" and diffuse rear zone that helps to spread out the surrounds' sound field, which enhances ambiance, retains some sound power, and simulates a commercial cinema)
Pros and Cons of each model
What the ETC typically should look like for these models
Levels of attainment for theaters, starting with the no-brainer, critical, bang-for-buck, and low-hanging fruit stuff, progressing to more difficult, expensive, less ROI, but delivering the last 30% of the room model's goals.


----------



## kromkamp

There's room to discuss everything here. If we were just limiting it to basic DIY treatments we wouldn't need 291 pages to cover that










My point was that people shouldn't get frustrated when they offer advice and people here respond that they are unwilling to go to certain extremes for very valid practical reasons. Doesn't mean they aren't learning or aren't willing to incorporate some of that information into their designs.


----------



## Eyleron

*What Do Surfaces and Treatments Do to FR?*

I read Toole's latest book a while back, but I can't remember if there's good graphics of how the frequency balance changes when reflected from different materials of different absorption characteristics?


It would be edifying to see this.

"I had a flat response coming from one speaker.

THIS is what the response curve looks like coming from this drywall/2" panel/etc.

THIS what my ear will hear."

*Achieving Room MOdels*

The best diagrams / photos / experiments / case studies on blocking and string method should be reproduced here.


Honestly, the experts would save themselves thousands of hours of retyping the same stuff if they could make this more accessible to laypeople.


Progress from how a bouncing ball indicates the ball's positional translation over time, to how an ETC shows the reflections the impulse hit over time. Relate the ETC to diagrams of a room, to real photos of such a room prior to treatment.

*Case Studies*

Show us how you found some real problems (the room isn't matching the desired model), measured to find the source of the problem, and tackled that problem with treatment.


(This should be in the room model primer I mentioned above)


Do so in a way that can be...
Minimally applicable for the casual family room (which I suppose is its own model) where low-hanging fruit that fixes the worst problems for a realistic family room model.
Low effort / expense applicable for a dedicated theater room. Under $1,000 of treatment, under 50-100 hours of effort?
Medium effort / expense, where one might get into some diffusion, maybe a pressure trap, some room construction, be willing to sacrifice more room dimensions, etc.
Maximal achievement of the criteria for the room model.


I'm not necessarily addressing the acoustician, or the professional theater designer, but rather anyone who has tackled these issues and likes to help and educate. We have hundreds of theater build threads, where some of these issues are addressed. We have hundreds+ of specific room challenges or DIY treatment construction, but not tackling the room model in a holistic, start-to-completion fashion.


It's like seeing fragments of bird house theory, and bird house painting, and components of the bird house plans, and some of the bird house construction.


Although every room and every user is different, there's still great merit in seeing how others tackled their challenges.


----------



## Eyleron




> Quote:
> Originally Posted by *kromkamp* /forum/post/21681645
> 
> 
> My point was that people shouldn't get frustrated when they offer advice and people here respond that they are unwilling to go to certain extremes for very valid practical reasons. Doesn't mean they aren't learning or aren't willing to incorporate some of that information into their designs.



Right, and that's what I was alluding to when talking about different groups interfacing with other groups.

*Acousticians should realize* that when someone is asking about a modal issue, it doesn't mean that he's unaware of or hates specular issues and thinks the ETC is lame. Or when choosing to focus on porous traps is unaware that there are other more effective, albeit expensive / difficult methods. Surely I can talk about a consumer sports car without being told that custom-built race cars are more effective. And experts should be *sensitive to the real constraint-plagued world of home theaters*, or they will forever be frustrated at people's reticence at achieving the entire 100% of a room model, or not implementing the most effective treatment, and we'll never get help we can actually use, and people new to this area are turned off.


Conversely, the *veteran should clarify what his goals* (room model, specific issue one's trying to tackle) and *constraints* (effort, financial, aesthetics) are. Pepar has done this by stating what construction & deconstruction he's willing to undertake. Failing to do this is like saying "I want a speaker, which is best?" Without that initial planning work in understanding the *models and targets*, it's hard to engage in discussion about application.


I also agree with the above in taking issue with being compared to pro studio builders. That's like comparing the DIY home renovator to a professional construction company owner. Or the sports car hobbyist to the race car builder. The home theater is for fun in their home; the GearSlutz user is probably doing this as a business, where the quality of the studio mix output will affect his livelihood. The studio world also has a longer legacy of implementing models. The acoustic models appear to originate in the context of building better studios, although I think a lot of that research has its roots in professional performance spaces (and thus the challenges in translating theory and practice from the large to the small).


----------



## Dennis Erskine

Just for reference, when sound conflicts with an object, some of the sound will transfer through the object, and/or be reflected, and/or be absorbed. Any time sound is reflected off an object there will be a frequency and phase shift. Whether or not those shifts are audible or distracting is subject to an entirely different discussion. Anytime you're in a chamber room, auditoria, or shower stall the surrounding environment is affecting what you hear and perceive. That's life. That's they way it is. We humans have adapated very well to living and playing in boxed in spaces. A fine Bosendorfer or Strad will sound different in Carnegie Hall, Mechanics Hall or the Kennedy Center.


----------



## Dennis Erskine

Reflection-Free Zone

Live-End Dead-End

Ambiechoic

...


All of these are different approaches to achieve the same goal ... accurate (and pleasing) sound reproduction. In the end, if what you really, really, like is the sound in Mormon Tabernacle or Meyerson Hall ..., well you'll just have to buy the building.


----------



## cybrsage

Can't I just push the button my AVR to simulate those spaces?


----------



## kromkamp

Continuing that thought, is it worth describing again with more detail the kinds of room problems that we do want to fix, and by how much?


As dragonfyr put it, what is the specific acoustical response goal we want to hit for a residential, small room home theater?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *kromkamp* /forum/post/21681645
> 
> 
> There's room to discuss everything here. If we were just limiting it to basic DIY treatments we wouldn't need 291 pages to cover that



At 8737 posts and counting, this thread is quite unwieldy - honestly, I think there needs to be a separate forum dedicated to acoustic treatments and soundproofing.


----------



## Dennis Erskine




> Quote:
> Can't I just push the button my AVR to simulate those spaces?



Yamaha made that rather reasonable approach starting with the DSP-1


----------



## pepar




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21681974
> 
> 
> At 8737 posts and counting, this thread is quite unwieldy - honestly, I think there needs to be a separate forum dedicated to acoustic treatments and soundproofing.



How to implement and then get that to work though? The Audyssey thread is 50k posts and we periodically gnash our teeth over people not reading the first post, not searching ... basic forum skills and etiquette ... and how a new thread should be started that is dedication to this or that subtopic. And then we all come back to "this thread is highly active, is at the top of the page and people will continue to click on it and ask their question regardless of what other threads are created."


Not saying it isn't a good idea, just tossing out food for thought.


BTW, this discussion is GREAT. Perhaps something constructive will come out of the latest feather ruffling.


Jeff


----------



## NicksHitachi




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21681974
> 
> 
> At 8737 posts and counting, this thread is quite unwieldy - honestly, I think there needs to be a separate forum dedicated to acoustic treatments and soundproofing.



+1 and leave this one for theory banter.


IMO if you have to quote a scientific paper to support your view your probably deep in left field theory territory and of little use to the average DIY HT enthusiast.

*I challenge one of the elite folks here to Erskine, Winer, etc. to start a thread focused on the low hanging fruit for DIY HT folks.*


Some simple starting points that would get most of us 90% of the way there. I'll bet most will agree on the best starting points. Getting the last 10% is where all the theoretical discussions and differing of opinions convelude the simple things which would make the average HT better.


----------



## Eyleron




> Quote:
> Originally Posted by *kromkamp* /forum/post/21681868
> 
> 
> Continuing that thought, is it worth describing again with more detail the kinds of room problems that we do want to fix, and by how much?
> 
> 
> As dragonfyr put it, what is the specific acoustical response goal we want to hit for a residential, small room home theater?



Absolutely! I don't know if it should be here, or in Bigus' thread, or wherever.


The first task is understanding that there ARE different models.

Next is understanding their differences and how that applies to home theater.

Then picking one, which as Dennis is suggesting, may be a more subjective choice.

Last, implementing it to some degree.


----------



## Eyleron




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21682217
> 
> 
> Some simple starting points that would get most of us 90% of the way there. I'll bet most will agree on the best starting points.



Yeah, I see people here wanting to know, "What's the stuff that probably applies in 80% of the cases that probably won't do harm, that I don't need to spend 100 hours in planning to determine whether I should implement?"


Maybe porous corner bass traps fall in that category, but your chosen model would dictate what the front corners are doing with mid-to-high frequencies. You can broadband absorb, diffuse, only absorb the bass, etc.


And maybe "lastly after other bass treatment, EQ in modal region those peaks that are consistent for your important seats, where it's minimum phase."


The rest depends on the model, but if we're talking home theater, and not a large choral performance space, I suspect some of the models can be winnowed down due to the use of multi-channel source and speakers providing some of the ambiance, as well as real-world constraints like not being able to cover all the surfaces with diffusors.


The room model thread ended in January with two pages, last post by kromkamp. It should be continued, maybe with more concerted intent at coming to agreement, rather than disagreement.


----------



## pepar




> Quote:
> Originally Posted by *Eyleron* /forum/post/21682280
> 
> 
> The room model thread ended in January with two pages, last post by kromkamp. It should be continued, maybe with more concerted intent at coming to agreement, rather than disagreement.



Well, four or five posts into that link, I encountered the same lack of respect that just erupted here over the last several days. It's not the thread topic that makes or breaks a thread, it's members not interacting properly with others.


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21682217
> 
> 
> +1 and leave this one for theory banter.
> 
> 
> IMO if you have to quote a scientific paper to support your view your probably deep in left field theory territory and of little use to the average DIY HT enthusiast.
> 
> *I challenge one of the elite folks here to Erskine, Winer, etc. to start a thread focused on the low hanging fruit for DIY HT folks.*
> 
> 
> Some simple starting points that would get most of us 90% of the way there. I'll bet most will agree on the best starting points. Getting the last 10% is where all the theoretical discussions and differing of opinions convelude the simple things which would make the average HT better.



Here are two posts that get to some basics - I have these bookmarked

http://larchive.avsforum.com/www.avs...3#post17390783 

http://www.avsforum.com/avs-vb/showt...8#post15406068 


From Bob's post, this always struck me as very basic - "In an otherwise empty/reflective room, studiotips superchunks and first reflection point absorbers are a good thing. In other rooms, your mileage will vary."


----------



## mtbdudex




> Quote:
> Originally Posted by *NicksHitachi* /forum/post/21682217
> 
> 
> +1 and leave this one for theory banter.
> 
> 
> IMO if you have to quote a scientific paper to support your view your probably deep in left field theory territory and of little use to the average DIY HT enthusiast.
> 
> *I challenge one of the elite folks here to Erskine, Winer, etc. to start a thread focused on the low hanging fruit for DIY HT folks.*
> 
> 
> Some simple starting points that would get most of us 90% of the way there. I'll bet most will agree on the best starting points. Getting the last 10% is where all the theoretical discussions and differing of opinions convelude the simple things which would make the average HT better.



I think Mr Winer;s book may help many people:
http://www.ethanwiner.com/book.htm 











> Quote:
> I've always wanted to write a book about audio, and a few years ago I started making notes about what I would include. As it happens, a major publisher of technical books approached me in early 2011 after seeing my hour-long AES Audio Myths video. So I submitted a proposal for my book, The Audio Expert, which they quickly approved. I worked on the book literally non-stop since then, and finally finished the first draft in late November. All 26 chapters were then sent to black belt technical editor Mike Rivers for his comments and suggestions, which I applied. (Thank you Mike!) I then did one final "polish" pass on the entire book, and sent it to the publisher January 8. The copy editor and layout department are now putting the book into its final form, then I'll review it one last time before it goes to the printer.
> 
> 
> 
> 
> This is a very comprehensive "reference" type book covering all aspects of audio, with many practical as well as theoretical explanations. It's written for people who want to understand audio at the deepest, most technical level, but without needing an engineering degree. The Audio Expert explains how audio really works in much more depth than usual, using common sense plain-English explanations and mechanical analogies, with minimal math. It's presented in an easy to read conversational tone, and includes more than 400 figures and photos to augment the printed text. You can view the Table of Contents now, which includes a list of all the videos that total more than 3-1/2 hours running time.
> 
> 
> However, this book goes beyond merely explaining how audio works. It brings together the concepts of audio, aural perception, musical instrument physics, acoustics, and basic electronics, showing how they're intimately related. It also describes in great detail many of the practices and techniques used by recording and mixing engineers, including video production and computers. This book is meant for intermediate to advanced recording engineers and audiophiles who want to become experts. It's definitely not a "Dummies" type book for beginners!
> 
> 
> One unique feature is explaining how audio devices such as equalizers, compressors, and A/D converters work internally, and how they're spec'd and tested, rather than merely describing how to use them. This book is also unique because it includes much original research, such as methods to test the audibility of distortion and other artifacts using your own listening system, while explaining why many common home-made tests are not valid. It also addresses the perennial "measuring versus listening" and "subjectivist versus objectivist" debates head on, and resolves them using science, logic, and hard proof. There's plenty of myth-busting and consumerism too. Indeed, truly understanding how audio gear works leads to smarter buying. So while I won't tell readers what brand power amplifier to buy, I explain in great detail what defines a good amplifier, so people can choose a first-rate model wisely without over-paying.
> 
> 
> Most explanations throughout the book are platform-agnostic, applying equally to Windows and Mac computers, and to most software and hardware. Many audio and video examples are included to better present complex topics such as vibration and resonance. Other videos demonstrate editing techniques and audio processing, and there are several video interviews with skilled musicians demonstrating their instruments and playing techniques. In the piano video, a professional piano technician disassembles a $100,000 Steinway grand to show how it works! Of course, there's also a comprehensive Acoustics section, bringing together much of my writings from past years into one coherent reference, along with a wealth of new information. There's literally nothing else like this book.
> 
> 
> The Audio Expert is due out April 15, 2012, with an anticipated length of 656 pages and a list price of $54.95. The book can be pre-ordered now at the Amazon book store, and will also be available as an eBook at the Kindle store. Watch for a glowing review in an upcoming issue of Electronic Musician magazine.



Upon looking at the chapters it's clearly for those in the making music business, sound engineering, so I asked could a reduced pdf online version be avaialble....
http://forums.musicplayer.com/ubbthr...ok#Post2383341 


> Quote:
> Originally Posted by *mtbdudex* /forum/post/0
> 
> 
> Ethan;
> 
> I'm a Home Theatre enthuasist.
> 
> Looking over your book table of contents, http://www.ethanwiner.com/book_toc.htm clearly it is written for those who are in the "music business".
> 
> Making, creating, recording, editing, playback, etc.
> 
> 
> For the Home Theatre related portions, is there any thinking to make say a smaller version, even download pdf only.
> 
> Ch 1, 2, 3, 4, 16, 17, 18, 19, 20, 22, 23, maybe some others.
> 
> Just a thought....


----------



## mtbdudex

btw, Low hanging fruit is very clear, it's been stated here and many-many other acoustic forums:


1) Pick RFZ zone as your small room acoustic model, it's the easiset for DIY (IMO); front sound stage specific ; I've not seen surrounds addressed specifically in the various small room acoustic model's ....

2) Broadband bass traps in corners, big ones if possible, 34" x 24" x 24" (use pink fluffy for that size). Soffit style on wall/ceiling is also.

Plan to cover them on room facing surface with thick kraft paper or 6mil plastic to reflect the mid-hi freq back into the room. Fabric cover over that.

3) Using mirror trick, plan where your side wall 1st reflection treatments could be

.....If you want to use measurement and verify exact placement, use ETC and the techniques discussed for ID/placement.

.....If not, using just mirror trick, you may over dampen slightly, or may not get all the reflection points, but definitley improvement will be heard (the 90/10 rule)

4) by the book for side wall treatments, 4" OC703 + 4" air gap is best to even absorption thru the freq spectrum 250hz and up, again 16" of space may not work for some, 2" + 2" air gap will leave some of the lower freq not addressed.

>>Trade off time for the customer to decide

5) Using mirror trick, plan where your ceiling 1st reflection treatments could be....same comments as 4) above.


Plan them

Build them

Hang them

Listen and enjoy them










Better is measurements, but many don't want to shell the $225 or so for measurement mic/gear and learn the software.

Not hard, but just one more thing in a busy life.


I see some are asking for a "Plan...do...check....act" cookbook approach.....











Looking at this link, everyone can see visually the various small room models, it's 7 pages from the book "Acoustics and Psychoacoustics Applied"
http://eetimes.com/design/audio-desi...n?pageNumber=0


----------



## Eyleron




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21683170
> 
> 
> btw, Low hanging fruit is very clear, it's been stated here and many-many other acoustic forums...



Seems reasonable and that it'd do the most good with the least harm.


----------



## sukumar




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21683170
> 
> 
> btw, Low hanging fruit is very clear, it's been stated here and many-many other acoustic forums:
> 
> 
> 2) Broadband bass traps in corners, big ones if possible, 34" x 24" x 24" (use pink fluffy for that size). Soffit style on wall/ceiling is also. Plan to cover them on room facing surface with thick kraft paper or 6mil plastic to reflect the mid-hi freq back into the room.



Is there any cons if chunk bass traps are covered with 6mil plastic paper surrounding three sides of triangle? If it is not advised, how do you stop fibers coming from the back or sides?


----------



## mtbdudex




> Quote:
> Originally Posted by *sukumar* /forum/post/0
> 
> 
> 
> Is there any cons if chunk bass traps are covered with 6mil plastic paper surrounding three sides of triangle? If it is not advised, how do you stop fibers coming from the back or sides?



Sorry not stated, they need fabric covers over the reflective material for that reason.

Plus, they need to look nice, right?


----------



## pepar

I think he's asking about totally encasing the SSC's in poly/kraft paper for environmental reasons.


Jeff


----------



## sukumar




> Quote:
> Originally Posted by *pepar* /forum/post/21683480
> 
> 
> I think he's asking about totally encasing the SSC's in poly/kraft paper for environmental reasons.
> 
> 
> Jeff



Yes. that is right. I wonder encasing triangle basstrap in 6 mil plastic instead of just front side is ok or causes any problems.


I intend to encase first with 6mil plastic then with fidelio velvet cloth.


----------



## mtbdudex




> Quote:
> Originally Posted by *sukumar* /forum/post/0
> 
> 
> 
> Yes. that is right. I wonder encasing triangle basstrap in 6 mil plastic instead of just front side is ok or causes any problems.
> 
> 
> I intend to encase first with 6mil plastic then with fidelio velvet cloth.



As I type this on my iPhone, in my basement home theatre, watching pirates of the carribean with my 6 yr old son, I'm looking at 6 bundles of pink fluffy sitting wrapped in their plastic still.....there for some side experiments on low freq bass stuff....need I say more.


Many people buy and stack pink fluffy in the corners. Sure, it's compressed, but gives you directionally the improvement possible. Uncompress it for the install.

Fully wrapping in plastic is up to you.


I believe dragon or local posted some link to clear the issue of health of loose fibers, simply a non issue.


Have fun.


----------



## fotto




> Quote:
> Originally Posted by *sukumar* /forum/post/21683558
> 
> 
> Yes. that is right. I wonder encasing triangle basstrap in 6 mil plastic instead of just front side is ok or causes any problems.
> 
> 
> I intend to encase first with 6mil plastic then with fidelio velvet cloth.



+1 on what Mike said, plus, if the traps are behind a false wall, it's just silly to spend the cash on Fidelio. Go to Joanns and buy some some cheap speaker cloth to cover. Save the Fidelio for the screen frame, although I personally think that's overkill as well compared to some less expensive options.


----------



## sukumar




> Quote:
> Originally Posted by *fotto* /forum/post/21684196
> 
> 
> +1 on what Mike said, plus, if the traps are behind a false wall, it's just silly to spend the cash on Fidelio. Go to Joanns and buy some some cheap speaker cloth to cover. Save the Fidelio for the screen frame, although I personally think that's overkill as well compared to some less expensive options.



Thanks. I already bought 20 yards of Fidelio and it is sitting for a while. After buying, I got confused if it is accoustically transparent enough for sound absorption and did not do anything with it. At the time of purchase, my intention was to make screen wall and surroundings as dark as possible and never thought about filling space with bass traps or first reflection panels.


----------



## nathan_h




> Quote:
> Originally Posted by *nathan_h* /forum/post/21668701
> 
> 
> 
> 
> Quote:
> Originally Posted by *dragonfyr* /forum/post/21666491
> 
> 
> Nathan, we can help you. But help us by posting the REW .mdat file so that we can convolve the frequency response into the various views and window them accordingly.
> 
> 
> And as local observed, we want to drive each source individually with the measurement mic remaining in the EXACT same (reproducible) position for all current and future tests.
> 
> 
> And with treatment in place, its difficult to say what can be done, or what original actual issues exist that require treatment and thus to suggest what needs to be done, as we do not have the untreated baseline response to judge. Untreated measurements would be a wonderful addition if the concept does not scare you too badly... We can then determine the effectiveness of the treatments and suggest any additional measures...
> 
> 
> And seeing as how REW can be used in any number of configured audio topologies it hardly seems work all the effort to attempt to configure it to a specific configuration when it is simply but one possible topology out of many when its easier and quicker to simply manually change the input relative to the device you want to test.
> 
> 
> 
> 
> Okay, once I get the measuring of individual speakers working, I'll post the mdat file. I assume the one for the stereo pair isn't as useful, interesting?Okay, once I get the measuring of individual speakers working, I'll post the mdat file. I assume the one for the stereo pair isn't as useful, interesting?
Click to expand...



Working on getting set up to test speakers individually. First step was just to remove bass mgmt, the sub, etc and do a fresh measurement of the room with all channels driven with the test sweep.


Calibrated mic from Dayton. I'll post the mdat file and this picture set of pictures.


EDIT: mdat file is 1.7mb and the upload limit is .5MB


----------



## nathan_h

Single speaker measurements. Right front, run full range, no sub, no eq, etc.


----------



## localhost127

nathan_h, it is best to post the files (upload to www.sendspace.com ).


also, ETC needs to utilize loopback --- in preferences/analysis, DE-select 'T=0', Select 'use loopback for timing reference', and DE-select 'decimate IR'


re-run the test and post .mdat files (one speaker/source at a time).


----------



## nathan_h

I'll re-run ETC, but for now, here is the mdat for the single speaker test.

http://www.sendspace.com/file/n56o2r


----------



## Cliffside Pirate

I am looking for some advice and may have some dumb questions, but would really appreciate the help.


I ran across a really good deal on (4) Thiel PowerPlane 1.2 speakers. I already have the speakers for a surround sound setup in a HT without using these speakers for that. I am in the process of building a garage building with a finished space above. In the garage area, I am planning to install a projector and am thinking about installing the four Thiel speakers in this room (the room is 30' x 40' with 12' ceiling). I will use this primarily to watch sports when people are over and listen to music. Upstairs, I plan to setup more of a theater with surround sound. I would like to hook everything up through one receiver and I am looking at the Yamaha Aventage RX-2000. Will I be able to send video to my theater room TV and the projector as well as power all of the speakers with this one unit? Do I need an amp for the Thiel speakers or will this receiver work without an amp?


Again, any advice is appreciated as I am trying to learn as I go and make sure I make the right decisions as I am in the build process on the new building right now.


----------



## pepar

This is the acoustical treatments thread ...


----------



## nathan_h

yeah, i recommended he ask here, since i've seen a few discussions of the calculations regarding speaker sensitivity, spl, and amp output. there might be a better place to ask but i couldn't think of one...


----------



## pepar




> Quote:
> Originally Posted by *nathan_h* /forum/post/21718750
> 
> 
> yeah, i recommended he ask here, since i've seen a few discussions of the calculations regarding speaker sensitivity, spl, and amp output. there might be a better place to ask but i couldn't think of one...



Probably be more likely to get good advice on a Thiel thread or one for the receiver. Members on a Thiel thread would be familiar with the speakers.


Jeff


----------



## nathan_h

reasonable suggestion.... ironic that *that* is where he posted at first.... crickets.


----------



## pepar

Maybe they are all off enjoying their speakers.


----------



## nathan_h

bingo


----------



## Eyleron




> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> reasonable suggestion.... ironic that *that* is where he posted at first.... crickets.



Maybe this was the wrong thread but the right forum, if it has to be one question.


Or it could be two questions: one in Thiel and one in receivers.


----------



## nathan_h

Opinions on two different diffusers sought:


I have been using broad band absorption, the basic GIK panels, on my side wall first reflection points.


Recently, I got a good deal on some cheap Auralex Metrofuser panels. They are shallow and made of styrofoam, but I figured it would be an interesting experiment to place them over the side wall panels and see what I thought.


The result? Bigger soundstage and all spatial cues appear to be preserved.


So now I'm sold on the idea of diffusion at my side wall fist reflection points.


But these panels may not be ideal. I'm still trying to learn, but so far what I have picked up is:


The pattern should not repeat,though being mirrored is okay. In that case, since the panels are 24" square and I only have to cover 4' square, they should be okay.


The depth should be shallow, when seated lose to the panels. I'm about six to seven feet from the side wall reflection points, so I think that's considered close. These panels are only two inches deep, so the wells are even shallower, so I think that's good.


But they are made of styrofoam, which can't be spray painted and would probably still have low WAF even when painted. And I cannot tell what calculations were used for them.


So I am considering two upgrades:

http://www.decware.com/p1324.htm look good, and buying as a kit makes them affordable. The narrowness of the wells seems to mean their diffusion only happens at higher frequencies.


The other option is the QRD panels from GIK. They are bother wider (which I think is good in that it means a wider range of frequencies are impacted) but they are also deeper, which I suspect is not ideal in the close quarters I'll be using them in.


Thoughts?


----------



## Eyleron

How about a third option: BAD panels for way higher WAF?


They diffuse and absorb the LF.


EDIT: I didn't phrase that well above. For the record, it looks like they diffuse upper and mid frequencies and absorb lower than their diffusion threshold, such as 1000hz, depending on the particular model's design.


----------



## nathan_h




> Quote:
> Originally Posted by *Eyleron* /forum/post/0
> 
> 
> How about a third option: BAD panels for way higher WAF?
> 
> 
> They diffuse and absorb the LF.



Those look interesting, but I don't think I'd get 32 square feet of coverage for 600 bucks, like the other two solutions. She's okay with the look of these others. It's just the styrofoam panels that have to go


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21731805
> 
> 
> Nathan...
> 
> 
> Lots of issues using those panels.
> 
> 
> First, their effective bandpass is FAR too high. To be effective over the broadband bandpass, you are going to need QRD style diffusors generally about a foot deep to get the lower extension required.
> 
> 
> With the Auralex product you are effectively EQing the reflected energy seriously coloring the direct sound. The minority of he mid and low mid energy does not even see them and effectively see a flat wall surface.
> 
> 
> If you'd like a more complete explanation and additional practical options, PM me and we can talk by YM, Skype or telephone...



Having been reading this thread for a few years, I think a conversation about diffusion here may be useful (I don't recall seeing lots of details). Thanks for the offer to take it off line. But if we can keep it online, I suspect others may find it interesting/useful.


My understanding so far is that to get impact over a broad frequency range, I need a panel with WIDE wells, and to get a panel that is impactful at short distances, I need a panel with SHALLOW wells.


So I agree the Auralex aren't the right ones. And the DIY kit I list doesn't have wide enough wells. I was actually thinking the GIK panels might be too deep.


But you are suggesting the GIK panels aren't deep enough, correct? (I've mentioned three different commercial solutions in my post, so when you say "those panels" I'm not sure if you mean all three, of just the Auralex ones.)


----------



## localhost127

read over this a few times - http://www.subwoofer-builder.com/qrd.htm 

collo did an excellent job with the tech guide and perfectly suitable for the novice.


----------



## pepar




> Quote:
> Originally Posted by *localhost127* /forum/post/21732441
> 
> 
> read over this a few times - http://www.subwoofer-builder.com/qrd.htm
> 
> collo did an excellent job with the tech guide and perfectly suitable for the novice.



Thanks. Bookmarked.


----------



## localhost127

dont bookmark it - read it.


and here's the original discovery thread if anyone is interested:
http://www.gearslutz.com/board/bass-...-possible.html


----------



## nathan_h




> Quote:
> Originally Posted by *localhost127* /forum/post/21732441
> 
> 
> read over this a few times - http://www.subwoofer-builder.com/qrd.htm
> 
> collo did an excellent job with the tech guide and perfectly suitable for the novice.



Yep, that's the only coherent overview that I have found without a lot of marketing hype related to one brand.


What I conclude from it:


1. The auralex panels are shallow enough for near field use but lack with width of individual wells that would have impact on midrange frequencies and don't have fins which impacts performance.


2. The GIK panels (QRD) have the width of wells that would get down into the midrange, but are deeper than ideal for near field use (but maybe my seven foot distance is okay). But again no fins.


3. The DIY kits are great for near field, but also suffer from narrow widths meaning they don't get into the midrange.


Conclusion: The GIK is the least compromised of the choices for my application.


----------



## localhost127

what on earth do you mean by "brand"??? we're talking number theory here..


and fyi there is a reason why this book is constantly recommended:
http://www.amazon.com/Acoustic-Absor...dp/0415471745/ 


i suggest you investigate your local library.


me personally, i dont see any reason to utilize any QRD or PRD under N23.


----------



## nathan_h




> Quote:
> Originally Posted by *localhost127* /forum/post/21733626
> 
> 
> what on earth do you mean by "brand"??? we're talking number theory here..



Every manufacturer seems to have their secret sauce, like RPG and RealTraps using absorption / diffusion combination products, or Auralex no longer publishing specs and test results, though they did at one time, and imply there is science behind their offerings.



> Quote:
> and fyi there is a reason why this book is constantly recommended:
> http://www.amazon.com/Acoustic-Absor...dp/0415471745/
> 
> 
> i suggest you investigate your local library.
> 
> 
> me personally, i dont see any reason to utilize any QRD or PRD under N23.



I am finding that the statements about controlling modal energy through traps and specular energy through diffusion are also matching my listening impressions (or vice versa) so I am on the hunt for affordable diffusion.


I haven't read the book, just the web site, so I am not sure I understand why an N7 QRD panel is less desirable than absorption at a side wall first reflection point.


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/0
> 
> 
> 
> Sorry, but you are jumping to conclusions on the basis of marketing brochures rather than a familiarity of the concept based on mathematical sequences behind how they work!
> 
> 
> As local has observed, of only folks would first avail themselves of just a few definitive texts rather than the myriad hours and number of marketing pamphlets folks with which seem to be intimate! And then we get to listen to the excuses as to why the sources are not read...
> 
> 
> Secret sauce? What? They optimize them or they don't. Or in too many cases, in the name of ease of manufacturing they cut corners and spun that as a unique feature. The basis for the design was developed by Dr. Manfred Schroeder. Hence why this style of diffusor is commonly referred to as a "Schroeder diffusor". There is no secret. Well, except to folks who spend more time reading marketing brochures than actual explanations of the principles!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And all of the combinations are rather easily understood. There is no secret! Simply an understanding of the basics that allow folks, in conjunction with an understanding of what is happening in a bounded space, and an awareness of how such behavior would befit from being modified, to put the behavior in the room together with the behavior of the various treatment device/material characteristics so as to appropriately address the full spectrum which needs to be addressed.
> 
> 
> Modes can be controlled with diffusion, but as one would quickly learn in the introduction of AA&D, this is not commonly done as the size of the diffusors is prohibitively large. If you want an idea of just how large, look at the PRD diffusors used in Blackbird above and note that they barely get down to ~110 Hz - and that is at the expense of losing ~7 feet of space to the diffusors.
> 
> 
> You would also quickly learn that the issue with size and spacing away from boundaries for velocity based porous absorbers is a fundamental limitation for them as well - with the optimal tool for such modal issues being pressure based tuned resonant absorbers - which are a bit more complex to design and to iteratively install and tune.
> 
> 
> And a single n7 QRD is not going to do much for you. As also basic to their function is the issue of periodicity and the advantage of an increase in the complexity of the dispersion of he various reflected wavelets and their increased interaction (superposition). Basically you have a choice of going with fewer complex high n units, or a larger series of low n units incorporating an inverse unit inserted per the Barker modulation sequence. But seldom will one low n unit be used alone. They also have spacing requirements, as since diffusers typically used in rooms have a lower frequency limit of around 300-500 Hz, a minimum distance of 3 yards/meters is ideally recommended, but this is often compromised with the result being hat the lower octave is characterized by more scattering than diffusion..
> 
> 
> Again, ALL of this basic information about their function and design is rather elegantly addressed in the 2-3 page tutorial on the QRDude webpage, or in yet more detail, including applications, in AA&D.
> 
> 
> This stuff isn't that difficult. So again, and pardon me for harping on it, but PLEASE (anyone who has questions) at least do a BIT of actual research into this stuff. And then we can spend more time addressing real concerns rather than debating marketing claims that should be rather easily addressed by an informed user/consumer of such tools.



I read the QRDude web page, and shared my conclusions based on what I understood from those pages.



> Quote:
> Originally Posted by *nathan_h* /forum/post/0
> 
> 
> 
> What I conclude from it:
> 
> 
> 1. The auralex panels are shallow enough for near field use but lack with width of individual wells that would have impact on midrange frequencies and don't have fins which impacts performance.
> 
> 
> 2. The GIK panels (QRD) have the width of wells that would get down into the midrange, but are deeper than ideal for near field use (but maybe my seven foot distance is okay). But again no fins.
> 
> 
> 3. The DIY kits are great for near field, but also suffer from narrow widths meaning they don't get into the midrange.
> 
> 
> Conclusion: The GIK is the least compromised of the choices for my application.



If I am misunderstanding the concepts, it's not due to lack of trying.


As best I can tell, dual, mirrored QRD diffusers on each wall at the first reflection points is going to be my best option under $1k.


If there is something better for that four feet wide, seven feet tall section of side wall treatment, I am eager to learn.


----------



## pepar




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21735512
> 
> 
> I would suggest a few initial considerations.
> 
> 
> ... I would suggest that you first focus on ascertaining what is actually happening over the full time spectra of the room response, and then develop a comprehensive strategy rather than simply focusing on one treatment out of context with the whole ...



Thank you!


----------



## nathan_h

I've done some measuring with REW, posted above, but this was with GIK absorption panels in place on the side walls. I think the next step is to do those measurements with bare walls.


----------



## myfipie




> Quote:
> Originally Posted by *nathan_h* /forum/post/21736258
> 
> 
> I've done some measuring with REW, posted above, but this was with GIK absorption panels in place on the side walls. I think the next step is to do those measurements with bare walls.



Hey Nathan,

I would recommend sending us your measurements through email also. There is no reason to go around and around with stuff like this.


----------



## myfipie




> Quote:
> The fact is, with real measurements much is possible, and the only "reason to go around and around with stuff like this" is that we do NOT have functional measurements nor an established response goal nor even adequate information about the space in which they are to be installed



I asked him to send measurements so we could see if it is a good fit.


I am not sure if you aimed your other part of your post at my company or not but we have been selling diffusion for 5 of the 7 years of being in business. And we are getting ready to put a new line of tuned bass traps on the market. Care to beat me up on that?


----------



## nathan_h

The room is 17' x 12' x 7.6'. So placing a panel (or any type) along the side wall first reflection points means it's about 7' from the MLP.


I have measurements from the MLP, with one channel driven and with all channels driven.


Here is the measurement for one channel, in the current room, full range without the sub: http://www.sendspace.com/file/n56o2r 


(Which are better? Should I re-run the measurements without any treatment in place at the side wall reflection points?)


For standards, I need some guidance. Which of the following or some other standard is best to strive for? I am optimizing just for the front row.


IEC 60268-13?

ITU-R BS 1116-1? or the variant EBU 3276?


Summary of the standards, attached, and some photos of the room.


It may be hard to see from the photos, but I have:


1) two GIK 242 panels on each side wall first reflection point area, for a total coverage of 4' x 4'.

2) a bass trap 2 feet tall, 6 inches thick, running the full length of the front wall, at the floor/wall intersection, simple OC700 series, set off the front wall by 2 inches.

3) There is an additional GIK 244 panel on each side walls, right at the screen wall -- ie, not at a reflection point, but essentially in the corner, for bass trapping

4) and two GIK244 traps on the back wall, more or less centered above the back row chair backs.


But being a tinkerer, I picked up some cheap diffusion panels (metrofusers) from Auralex, little 2inch think stryrofoam panels, and placed them over the absorbers at the side wall first reflection points -- and liked the change. But I know those panels are not ideal -- little depth, ugly, and no stated specs or science behind them.


My general notion, pending education, is to replace #1 with diffusion (and re-purpose the 242 panels into corners for bass trapping).


----------



## myfipie




> Quote:
> But it is nice to see the all too common nonsensical "you can't have too much absorption" phrase slowly begin to wax in popularity on these forums. Including by representatives of some of the same firms to which you mention. And that has only been occurring in only the last 2-3 years!



Upper frequency absorption? sure. Bass trapping? Most small rooms need as much as they can get. As a company we have always offered custom builds of just about anything, but most people do not have the budget which is where broad band fits the bill a lot of times.

How is your room treated? Pictures you can share? Testing you can post?


----------



## myfipie




> Quote:
> Originally Posted by *nathan_h* /forum/post/21741207
> 
> 
> The room is 17' x 12' x 7.6'. So placing a panel (or any type) along the side wall first reflection points means it's about 7' from the MLP.
> 
> 
> I have measurements from the MLP, with one channel driven and with all channels driven.
> 
> 
> Here is the measurement for one channel, in the current room, full range without the sub: http://www.sendspace.com/file/n56o2r
> 
> 
> (Which are better? Should I re-run the measurements without any treatment in place at the side wall reflection points?)
> 
> 
> For standards, I need some guidance. Which of the following or some other standard is best to strive for? I am optimizing just for the front row.
> 
> 
> IEC 60268-13?
> 
> ITU-R BS 1116-1? or the variant EBU 3276?



Can you just zip the file and post it here?


----------



## nathan_h




> Quote:
> Originally Posted by *myfipie* /forum/post/21737022
> 
> 
> Hey Nathan,
> 
> I would recommend sending us your measurements through email also. There is no reason to go around and around with stuff like this.



Thanks. In addition to the link to the measurements, I have sent a note to you and Bryan.


Can't upload to AVS, since a zipped mdat file from REW is above the AVS max size for attachments.


----------



## nathan_h

Okay, I'll re run the test. I didn't have loop back set up, so all the absolute timing measurements are wrong -- though the relative times are valid.


----------



## fotto




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21742186
> 
> 
> And please generate the sweep with NO smoothing - as that extra information is actually useful.
> 
> 
> That said, you have a substantial high gain very early arriving reflection that will be VERY audible.
> 
> 
> That said, here are a few quick observations...
> 
> You have quite a few sparse (isolated) specular arrivals that would benefit from being resolved to their point of boundary incidence
> 
> 
> The early arrivals, as high in gain as they are need absorption, as diffusion will not address them to the degree necessary to mitigate associated problems.
> 
> 
> The other lower gain early reflections can benefit from diffusion (or absorption depending upon the logistics and whether diffusion may aggravate other concurrent behavior).
> 
> 
> The later arriving specular arrivals are dominated by many sparse reflections that are of much higher gain than the other proximal reflections. These interfere with proper localization.
> 
> 
> To the degree that these later arriving sparse reflections are primarily from the sides of the room would be to your benefit.
> 
> 
> These would greatly benefit from diffusion that would reduce the gain of the individual sparse focused reflection while spreading the energy out spatially and temporally - and optimally form a lateral orientation - thus increasing the density of the reflected energy soundfield, effectively 'filling in' the gaps and rendering the gain structure more uniform as it decays.



Nice post! I think this is the first time I've come across an actual analysis of the ETC with commentary on treatment relating to the measured data. Thanks.


----------



## nathan_h

Run again, using the loopback calibration.

http://www.sendspace.com/file/3nwjaq


----------



## localhost127

direct signal still arriving at T=0



http://imgur.com/BKd2Q.jpg%5B/IMG%5D



AC/electrical device causing interference?


----------



## dragonfyr

60 cycle

A classic example.


First try running your computer rig off battery only and see if that makes a difference.


----------



## RTROSE

Ok boys please be gentle.


I have perused this thread and needless to say it is overwhelming. I have searched reflection points, wall treatments, etc. and need a little more guidance. I would like to do some acoustical panels with some 703 I have acquired, and looking for the best method to determine where those panels should go and the general size of the panels. I have gleaned that a rough size of 2 x 4 and 2" thick is a general rule of thumb with a standoff from the wall of 2" or slightly less but not more than the thickness of the material. Is there a formula to determine where to place the panels? What is the flashlight mirror method, as well as the pool table school of thought. Again accept my apologies regarding the ignorant questions. I am trying to educate myself on all of this stuff and I am wading through lots of material.


Thanks in advance for your input.


Regards,


RTROSE


----------



## HopefulFred

RTROSE,

You've actually bumped into this thread at an opportune time (says me). The post above yours will likely be instructive in a number of ways. First, some basics.

Most non-bass sound in your room comes from your speakers and radiates out into the room in not all, but most forward directions. Like light, the sound can be envisioned as traveling in a straight line, like rays from the sun as drawn on a kinder-gardener's art project. When the sound hits the wall, it generally and mostly reflects like a billiard ball and keeps moving. The problem with this is that if that reflected sound gets back to your favorite seat at the wrong time (too soon, generally), your brain doesn't know what to do with the sound and it confuses your perception. Plain enough, right?


In a best case scenario, you'll hook up a microphone and some software to your system and generate graphs (like above) that show when reflected sound gets back to your seat. Once you know that, you can decide what to do about it. If you don't have the time or wherewithal to do that, you can position a mirror against the wall in various positions. Basically, if you can sit in your seat and see the speaker in the mirror, then the mirror is at a position to reflect sound back to you, just like the light forming the image in the mirror. Now, without the graph and some calculations you can't be sure that the sound reflecting at that point is going to interfere with your enjoyment, but if the spot is between you and the speaker, there's a pretty good chance it could do with absorption. There was a blog post just the other day that has good pictures to show you what the process might look like. http://acousticsfreq.com/blog/?p=432 


As far as size, it's harder to guess, but bigger is more likely to meet the needs of more seats - not just yours. So, theoretically, you'd repeat the process for all the seats (and all the speakers). I'd say start with the seat in one corner of your normal audience array and find the reflection points (there will probably be a good one on each side wall) for one speaker, then move to the farthest seat from that one and find the reflection points for the same speaker. That should pretty well define the maximum useful dimensions of that reflection site. Then move on the other speakers.


In terms of thickness and spacing from the wall, I think you've got the best practical approach already. If you have 2 inches of material, and can space it 2 inches off the wall, you are doing everything you can (given those materials) to ensure that your panel acts at all relevant frequencies. To some extent, the panels you propose will only absorb some of the sound that would otherwise be reflected. To the extent that some sound is still reflected, you should be aware that the reflected sound now doesn't have the same sonic character as the sound you like so much from your speakers - so it may sound odd. There is, in some ways, the potential for this to be off-putting and make you less happy than you were without the treatments at all, but don't let that stop you from trying it out - it will probably be great!


Keep in mind that a more thoughtful approach to this process, one which includes careful measurement and consideration of diffusion as well as absorption - not to mention redirection (reflection in a different direction) - will almost certainly yield better results. There are A LOT of tools in the tool box of a competent acoustic designer/engineer, and learning what they all are capable of is a serious project in the first place (one I'm working on now). If you have the materials to build a few panels (4? 6?), starting with the spots you can find with a mirror will at least let you get a feeling for the improvements you can make. You might even prop the OC703 against the wall in the likely problem spots and have a quick before-and-after listen, without even building a frame.


Fred


----------



## pepar

It's late, Fred. The reflected sound arrives late.










I'm sure when I wake up in another five hours I will read your post as saying that. Heck maybe it says that now and I just misread it in my early AM grogginess.










Great and helpful post though!


Zzzzz


----------



## nathan_h




> Quote:
> Originally Posted by *localhost127* /forum/post/21743484
> 
> 
> direct signal still arriving at T=0



Apparently the loopback for configuration (calibration) of the soundcard wasn't the loopback you guys are talking about. The REW documentation is pretty good, but that's the primary way they talk about loopback that I have found. I'll dig some more.



> Quote:
> 
> 
> http://imgur.com/BKd2Q.jpg%5B/IMG%5D
> 
> 
> 
> AC/electrical device causing interference?



Interesting. Not that I am aware of.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21743620
> 
> 
> 60 cycle
> 
> A classic example.
> 
> 
> First try running your computer rig off battery only and see if that makes a difference.



I do have an AV UPS I could run the computer off of. Is it enough that it's regenerating the power or should I actually unplug the UPS from the wall?


----------



## kromkamp

What criteria go into making the decision of how long the ISD gap should be? 20ms is often stated as desirable.


----------



## localhost127




> Quote:
> Originally Posted by *nathan_h* /forum/post/21746092
> 
> 
> Apparently the loopback for configuration (calibration) of the soundcard wasn't the loopback you guys are talking about. The REW documentation is pretty good, but that's the primary way they talk about loopback that I have found. I'll dig some more.



eg, you use a loopback on right channel for soundcard cal.


once that step is done,

you then would connect your receiver & mic into the right channel (output + input respectively), and move your loopback cable to the left channel on your pre-amp.


----------



## cuzed2




> Quote:
> Originally Posted by *RTROSE* /forum/post/21744881
> 
> 
> Ok boys please be gentle.
> 
> 
> I have perused this thread and needless to say it is overwhelming. I have searched reflection points, wall treatments, etc. and need a little more guidance. I would like to do some acoustical panels with some 703 I have acquired, and looking for the best method to determine where those panels should go and the general size of the panels. I have gleaned that a rough size of 2 x 4 and 2" thick is a general rule of thumb with a standoff from the wall of 2" or slightly less but not more than the thickness of the material. Is there a formula to determine where to place the panels? What is the flashlight mirror method, as well as the pool table school of thought. Again accept my apologies regarding the ignorant questions. I am trying to educate myself on all of this stuff and I am wading through lots of material.
> 
> 
> Thanks in advance for your input.
> 
> 
> Regards,
> 
> 
> RTROSE



RT,

Jump right in the water is just fine
















And just so I can tell you first; you need to post a layout of your room showing door openings, seating, etc etc.....


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21744067
> 
> 
> First a quick observation.
> 
> 
> One, loopback is not configured correctly.
> 
> Not sure what is going on with the configuration, and you can still use the empirical blocking method to resolve the vector paths of each reflection, but it makes it a bit more difficult to discuss it - so please note that any times we cite have nothing to do with the actual time of travel - they are just for 'identification'. Likewise, and time differentials stated, as merely for descriptive purposes and as such have NO necessary relation to actual times/distances.



I gotta figure this one out. I am sure it is a hookup issue with my (measuring) gear -- but the documentation on this is sparse.



> Quote:
> Another issue: I am also assuming that your walls are, for all intents and purposes, resistive/reflective to the specular energy in the room. As such all the incident energy will be reflected in a near identical manner save perhaps for energy loss. Thus there will be no effective coloration resulting from the walls as a result of their effectively and unduly EQ'ing the reflections. Most walls are resistive. But this is said as if they are not, an additional course of action is required.



Traditional sheetrock walls, a little thicker than domestic interior sheetrock, the firerated kind for use between a house and garage, for example. And all are insulated.



> Quote:
> Also, for the most part, it is assumed that the modal behavior has been addressed. Typically this will involve LARGE superchcunk style corner traps faced with a minimum of 6 mil plastic in order to act as a specular reflector. I also recommend making the traps asymmetrical; 24' at the side wall and 30 " on the front wall. this will generally allow the reflected energy to be redirected towards the back of the room without it being reflected back to the listening position. (You want to measure and confirm this behavior - and modify this as necessary.)



Got some superchunk-ish trapping going on -- mostly along the floor/wall intersection all the way across the front of the room. I could make this thicker.



> Quote:
> Your absorption is doing little of use. It appears to knock down a bit at ~3.94ms, but otherwise fails to mitigate the really glaring problems within what we will term the working ISD from 0ms to the first significant arrival at ~10 ms.
> 
> 
> Again, the first thing I would do is to resolve each sparse spike as to its vector path and point of boundary incidence, marking and labeling each with a piece of blue painters tape and noting the reflection # on the tape and ETC printout.
> 
> 
> You will want to do this for all of your sources with the mic remaining in the EXACT same position for all.
> 
> 
> And to make your day, this will be repeated for all sources for any other listening position you likewise wish to optimize.
> 
> 
> 
> 
> 
> 
> 
> (You can thank me later...) So you might want to think ahead and maybe obtain a few colored Sharpies for marking the tape and color coding your ETCs relative to the source. You might also want to mark each speaker with a piece of tape indicating the color you have assigned to it, as before long things will get a bit chaotic and its nice to be able to quickly sort things out.



Are we talking "the mirror method" or something more precise, to find these points?



> Quote:
> In a nutshell, here are your choices assuming that you want a defined direct arriving signal featuring maximal acuity as well as an enveloping sense of space that compliments the surround system and provides you with a sense of space should you play also 2 channel sources.



Bingo. Two channel spaciousness is important.



> Quote:
> In the ISD in the range from 0-~10ms, you will want to identify the points of incidence for all of the spikes exceeding about -14 dB down. There are several very prominent indirect sources that will need to be adsorbed.
> 
> 
> Here you have two choices depending upon your 'preference' - assuming you are able to figure out what you like.
> 
> 
> Regarding the signals that vary in level between about -18 to -12 db, you can absorb them and the result will be a very tightly well-defined image.
> 
> 
> Or, you can use broadband diffusion over the critical bands and diffuse such energy in order to both reduce its gain while increasing the spatial and temporal scattering effectively making the ETC soundfield more densely populated with more shorter spikes - changing it from a rather sparse landscape of varying heights, to a more uniform densely populated field with about the same height. The effect will make the image wider and less defined. You may like it. The greater the gain of this diffuse soundfield, the wider and less defined the image will be. But remember, if this option is chosen, the more uniformly diffuse the better!
> 
> 
> OK, that was simple, wasn't it?



I like option two better. Does "the more uniformly diffuse the better" mean more diffusion panels (after I absorb the remaining more prominent indirect sources)?



> Quote:
> Now for the later arriving soundfield.
> 
> 
> Again we have a decaying field with many sparse isolated high gain returns. These can cause localization errors in imaging as well as coloration.
> 
> 
> the goal for these is diffusion. To both mitigate the higher gain sparse reflections and to use their energy to make the decaying soundfield more spatially and temporally dense while maintaining a relatively even decay in the gain of the overall field. In other words, we are going to trim the 'hedge' and use the 'clippings' to figuratively fill in the gaps in the later arriving soundfield.
> 
> Reducing the level of the later arriving sparse reflections will remove false localization cue that detrimentally effect localization, imaging and colorization.
> 
> 
> This is effectively done by applying a series of properly chosen/designed diffusors along the back side walls beginning about 3ft off the floor with the well oriented anisotropically up and down if using Schroeder diffusors.



By "back side walls" do you mean BACK WALL and SIDE WALLS IN THE REAR?


Right now, I have roughly 4" of OC700 + 2" air gap panels on the back wall. To put diffusion there means mostly removing those two panels.



> Quote:
> (Another option, depending upon the degree of diffusion required is to employ binary amplitude diffusors, or BAD panels. But these are maximally effective when the sparse reflections are lower in gain as they are not as capable as the Schroeder QRDs in addressing high differential gain issues. But I mention them as an option. Also note, their spatial characteristics are not as well controlled as the Schroeders, thus much of the incident energy will be scattered in many directions that will not necessarily be returned in the horizontal plane and to the listening position... Not allot of qualification, but I mention it in passing. )



Actually, maybe that's better that QRD on the back wall?, since the back wall is 5' from the MLP, and there is a second row of seats, just inches off the back wall.



> Quote:
> But before we run on ahead, we want to see to what degree we can maximize the arrival of this energy so that it comes laterally - meaning primarily from the side walls. The more the better. This will increase the sense of envelopment and spaciousness of the space.
> 
> 
> The primary factor in this distribution will be the rear wall. If possible, energy incident upon it can often be redirected to the rear _side_ walls. It is here on the back wall that splaying can actually help. this can be combined with Superchunk bass traps with the reflecting or diffusing surfaces placed in front of them, effectively reflecting the specular energy to the side walls and back tot he listening position, while also helping to control modal behavior.



Interesting, splaying.


So there are really three possible back wall scenarios:


absorb

diffuse evenly

splay back to the rear side walls



> Quote:
> Note, this is HIGHLY simplified, and for multichannel measurements you are going to need to 'balance out' the gain levels of the various sources as in a surround environment you will have multiple sources incident at many of the same points of incidence.
> 
> 
> _So, this is NOT a comprehensive analysis and treatment plan._ Its a VERY quick napkin analysis based upon just one ETC with NO correlating information about the system or room. ...ALWAYS a dangerous thing to do! You Need to do the legwork to break this down and identify the actual factors that are at play. But maybe it will give you a feel for how it can be used.


----------



## nathan_h




> Quote:
> Originally Posted by *localhost127* /forum/post/21746127
> 
> 
> eg, you use a loopback on right channel for soundcard cal.
> 
> 
> once that step is done,
> 
> you then would connect your receiver & mic into the right channel (output + input respectively), and move your loopback cable to the left channel on your pre-amp.





> Quote:
> Originally Posted by *dragonfyr* /forum/post/21746144
> 
> 
> Nathan, the point is not to introduce still more electrical devices and possibly obscure the source more...
> 
> 
> The purpose is to eliminate variables until we identify the source of the problem.
> 
> 
> A common source of this can be the measurement platform itself. So if you are using a laptop sufficient to supply phantom power to the mic running off its battery (this means _no other_ connected peripherals connected to AC power! - including any connected that may not be in use - _none_), it removes an additional variable as a potential source.
> 
> 
> If that doesn't work, you get to go through your system configuration one change at a time and find out what device or interconnect is introducing the 60 cycle hum into the system. (it is indicated Very plainly by the ridge that does not decay at 60 Hz.)
> 
> 
> 
> And to amplify local re the loopback. It is a cable - just like you did for the 'soundcard calibration' that is now used to connect the left out to the left in. Yes, you read that correctly. The left/channel2 output back to the left/channel 2 input.
> 
> 
> In REW, you then go to Preferences-> Preferences-> Analysis and select "Use loopback as timing reference". Be sure that you do NOT have "Set t=0 at IR peak" selected, as this negates the loopback.



Loopback: Okay, next run, I do it right. More right, anyway.


60hz cycle: I'm using my project studio gear -- desktop PC (in another room), mAudio mic pre-amp with phantom power, mAudio soundcard in the PC, but the PC is output to the HT pre-pro via HDMI. I think I could run the PC off the battery system. If that doesn't solve it, I'll have to get creative with getting battery power to the mic preamp....


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21746524
> 
> 
> Never mind battery power. With that non standard configuration dependent upon so many internal PC components I would be shocked if you did not have 60 cycle hum!
> 
> 
> If you have the external pre-amp, you need to be by passing all of the additional gain stages and processing components in the PC. The mic pre-amp functions as the 'sound card'. You don't need the extra stages and they only introduce additional unnecessary issues with no advantages.
> 
> 
> You really need to follow the recommended configuration.
> 
> 
> All you need is the PC, the pre-amp, and the USB or Firewire connection to the PC. The connection to the AVR is done directly from the pre-amp!



My setup is:


mic -> mic-pre for phantom power -> soundcard -> computer -> AV pre-pro -> amp -> speaker


----------



## fotto

Nathan, perhaps a pic will help with the loopback stuff. Below is my set-up using the Art Dual Pre. You will see the right channel in and out connection options. In the case of when I did the calibration of the Art I had a cable connecting the Rin directly to the Rout. That was a one and done exercise to get the cal file. Now the Rout goes to AVR and the Rin is fed by the measurement mic.

What isn't shown on the Art pic is the second (left channel) in and out. For measuring with loopback, all I do is connect the Art's Lin and Lout via cable, and check the appropriate box in REW pref's as Dragon indicated. The loopback signal will be subsequently shown in the Ref In bar graph in REW.


----------



## localhost127

also, if you're running windows7 you will need to go into Control Panel / Sound / Recording tab / and go into properties of your USB pre-amp. go to Advanced tab, and make sure it is selected to 2-channel (default is 1channel). you will need to do this to utilize the loopback on your 2channel pre-amp.


you will also likely need to do this every time you connect the pre-amp to the PC if you connect it to a different physical USB interface (port) each time. i check it every time i connect by habit...


----------



## allan0210

Hi


Can anyone tell me please if a Behringer ECM8000 Measurement condensor microphone RTA is ok for use with REW software please?


Thank you


----------



## nathan_h




> Quote:
> Originally Posted by *fotto* /forum/post/21746618
> 
> 
> Nathan, perhaps a pic will help with the loopback stuff. Below is my set-up using the Art Dual Pre. You will see the right channel in and out connection options. In the case of when I did the calibration of the Art I had a cable connecting the Rin directly to the Rout. That was a one and done exercise to get the cal file. Now the Rout goes to AVR and the Rin is fed by the measurement mic.
> 
> What isn't shown on the Art pic is the second (left channel) in and out. For measuring with loopback, all I do is connect the Art's Lin and Lout via cable, and check the appropriate box in REW pref's as Dragon indicated. The loopback signal will be subsequently shown in the Ref In bar graph in REW.



Thanks. May take a couple days for me to get back and re-do this, but this helps.


----------



## allan0210

Thank you


If i explain i have tried to find the EMM6 mic in the uk but so far drawn a blank. I found the Behringer mic in the uk its a lot more but at least i have found one wish i could get one for $39


Being honest i have no idea what RTA is it was part of the description i thought itr was road traffic accident lol


Thanks



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21746829
> 
> 
> The mic, provided you have a calibration file from a company such as Cross Spectrum is OK.
> 
> 
> For those interested, calibrated versions of both the Behringer ECM8000 and the Dayton/Superlux EMM6 are available calibrated (and provided with the file to import) from Cross Spectrum labs.
> 
> 
> BTW, the Dayton EMM6 is available stock (for $39) with a provided calibration file, although some have suggested that it is not as accurate as the Cross Spectrum file...if you really need to save the money. But in any case, you WANT a calibration file.
> 
> 
> I am not sure what you are referring to by the "RTA"portion though, as it is not related.
> 
> 
> Nathan. the sequence should be:
> 
> 
> mic-> pre-amp right in
> 
> pre-amp -->PC via USB/Firewire
> 
> pre-amp left out -> pre-amp left in (loopback)
> 
> pre-amp right out -> avr in


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21746829
> 
> 
> The mic, provided you have a calibration file from a company such as Cross Spectrum is OK.
> 
> 
> For those interested, calibrated versions of both the Behringer ECM8000 and the Dayton/Superlux EMM6 are available calibrated (and provided with the file to import) from Cross Spectrum labs.
> 
> 
> BTW, the Dayton EMM6 is available stock (for $39) with a provided calibration file, although some have suggested that it is not as accurate as the Cross Spectrum file...if you really need to save the money. But in any case, you WANT a calibration file.



I went with the Dayton and calibration file.



> Quote:
> Nathan. the sequence should be:
> 
> 
> mic-> pre-amp right in
> 
> pre-amp -->PC via USB/Firewire
> 
> pre-amp left out -> pre-amp left in (loopback)
> 
> pre-amp right out -> avr in





Okay I gotta work on this. Just to confirm:


Chain one: mic -> mic-pre-amp right channel input -> mic-pre-amp right channel output -> analog connection -> PC sound card right channel input -> computer -> HDMI connection input on the AVR -> amp -> speakers


Chain two: mic-pre-amp left channel output (where is the signal from?) -> mic-pre-amp left channel in


----------



## kromkamp




> Quote:
> Originally Posted by *kromkamp* /forum/post/21746110
> 
> 
> What criteria go into making the decision of how long the ISD gap should be? 20ms is often stated as desirable.



I found something on the other forum that circles around the answer a bit:

http://www.gearslutz.com/board/6897592-post8.html 


But since we could never know the ISD gap for the recording room I'm not sure what conclusion to draw for a listening space...


Also, I'm curious: How do splayed walls compare with something like a polycylindrical diffuser (both in terms of the spacial and temporal distribution of the reflected sound)?


----------



## Dan Woodruff

Just as a Heads-up . . . gearslutz is on the McAfee warning list as an unsafe website.


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21747465
> 
> 
> The fact is, in a small listening room, 8-10 ms is fine. You make it as long as the room will reasonably support, generally determined by the time of arrival of the fist significant reflection. Its simply not worth getting into how the Haas interval time period can be manipulated and artificially made longer for such casual use.



That's very good to know, thanks. Would 8-10ms be considered a lower bound?



> Quote:
> Why are you splaying walls and we can answer the question.



Sorry, to be clear I am referring to your post above where you say



> Quote:
> It is here on the back wall that 'splaying' can actually help. this can be combined with Superchunk bass traps with the reflecting or diffusing surfaces placed in front of them, effectively reflecting the specular energy to the side walls and back to the listening position, while also helping to control modal behavior.
> 
> 
> If the above is not possible for some reason (???), then I would used diffusion on the back walls, placed in front of bass trapping.



I was just wondering how splayed walls in this scenario would compare with the use of a horizontal poly.


----------



## kromkamp




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21747597
> 
> 
> And a horizontally oriented poly would either bounce the energy directly back to towards the source at normal incidence and scatter it toward the ceiling and floor, which would be of little of no use to ward achieving the goal.
> 
> 
> But more fundamentally and simply, they are doing two completely different things, one that is beneficial to our goal, and one that is completely contrary to the goal of maximally redirecting the energy to the rear side wall to be diffused and returned to the listening position.



Understood. Just to be clear by horizontal poly I meant to scatter to the left and right - my nomenclature is wrong I suppose. But I get what you are saying.


----------



## myfipie




> Quote:
> All you need is the PC, the pre-amp, and the USB or Firewire connection to the PC. The connection to the AVR is done directly from the pre-amp!



Actually I have found the following USB soundcard/pre pretty easy to use with REW.
http://www.presonus.com/products/Det...x?ProductId=53 


As far as mic to use see the following.
http://www.realtraps.com/art_microphones.htm


----------



## RTROSE




> Quote:
> Originally Posted by *HopefulFred* /forum/post/21745265
> 
> 
> RTROSE,
> 
> You've actually bumped into this thread at an opportune time (says me). The post above yours will likely be instructive in a number of ways. First, some basics......_snip_....Fred



Thanks for that explanation Fred, I truly appreciate it. Lots of info to point me in the right direction.



> Quote:
> Originally Posted by *cuzed2* /forum/post/21746344
> 
> 
> RT,
> 
> Jump right in the water is just fine
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> And just so I can tell you first; you need to post a layout of your room showing door openings, seating, etc etc.....



Hey buddy thanks! Well right now it is like trying to take a refreshing drink from a fire hose! I'm sure as I enter into this next phase of my HT experience I will slowly but surely clear the glossy look in my eyes and start to understand some of this stuff.


Regards,


RTROSE


----------



## pepar




> Quote:
> Originally Posted by *RTROSE* /forum/post/21748406
> 
> 
> I'm sure *as I enter into this next phase* of my HT experience I will slowly but surely clear the glossy look in my eyes and start to understand some of this stuff.



Have a Plan B and C.


----------



## mtbdudex




> Quote:
> Originally Posted by *allan0210* /forum/post/21746858
> 
> 
> Thank you
> 
> 
> If i explain i have tried to find the EMM6 mic in the uk but so far drawn a blank. I found the Behringer mic in the uk its a lot more but at least i have found one wish i could get one for $39
> 
> 
> Being honest i have no idea what RTA is it was part of the description i thought itr was road traffic accident lol
> 
> 
> Thanks



If you use the generic cal file from HTS (same place as REW) it would get you in the ballpark.

Initially I bought an un-calibrated ECM8000 and used it.

The, when I got "serious" about measurements bought a calibrated ECM8000 from Cross Spectrum.

Here is comparision I made last year.

Granted this is a single comparision, I've seen the many comparision plot on HTS or another site.

Best is a specific cal file for that mic.









(this post reminds me, I'll sell this to a fellow SE Mich person for a deal, and tweak the cal file for him/her also)


----------



## nathan_h




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21747048
> 
> 
> No!
> 
> The right pre-out does NOT go to a PC sound card!
> 
> It goes to directly to the AVR aux input/amp/speaker!
> 
> 
> You are effectively sending the output of a 'sound card' to the input of a 2nd 'sound card'!
> 
> 
> The ONLY connection to the PC is via the USB or Firewire connection (depending upon the pre-amp format you are using)
> 
> 
> And the loopback is as stated as well, simply connecting the left output of the pre-amp back to the left input of the pre-amp.
> 
> 
> Exactly as I wrote above.
> 
> 
> 
> _Note also_, in response to your interpretation of my post #8759 , that I have gone back and fleshed out a few parts to qualify a few things leading to what may be misunderstanding. So, rather than qualify the qualifications that need correcting and further qualification, I tried to do it one spot. Any future mods will be made there as well.



Okay, I re-wired for the loopback -- measuring on L channel, loopback on R channel.

http://www.sendspace.com/file/uh8mx8


----------



## nickbuol

I have an acoustical question. I probably know the answer, but I thought that I would ask here anyway.


If I am trying to build a false wall to hide my front speakers & subs, plus hiding front corner bass traps and front wall treatments, I was planning on using AT panels surrounding at AT screen.


And then.... I started looking at my projector choice (a new JVC RS45) and while I don't *think* that I will even want 3D, I can't get a bright enough picture on a woven AT screen at a big size (around 130" diag) since the gain on woven screens seem to max out around 1.2 gain. Perf has some more gain options, but I like the idea of the smaller "holes" with woven...


I know, where is the question, right?


So what kind of nightmare would I end up with if I used black AT panels surrounding a NON-AT screen (higher gain and more brand options)? Speakers would be placed behind the AT panels obviously (to the sides for R and L, and under for the C channels). Placement would be similar to people without a false screen wall, but just behind it instead of in front of it.


So would that just turn things to total crap acoustically with sound bouncing around behind the screen?


----------



## nathan_h

that's viable


----------



## nickbuol

"That's viable"....


What is? That it could work, or that it will be crap?


----------



## nathan_h




> Quote:
> Originally Posted by *nickbuol* /forum/post/0
> 
> 
> "That's viable"....
> 
> 
> What is? That it could work, or that it will be crap?



It will work, or can work. I've seen it done in a few build threads though often people don't leave the space behind the screen empty. I think it will influence the speakers you want. Essentially something that doesn't mind being in a box/cabinet. How much space around the screen and from the false wall yo the real wall do you have?


----------



## nickbuol

Yea, I'm thinking that it will be crap. I already have my speakers, and they are even rear ported, so there is sound definitely coming out the back. Crappity crap crap crap...


----------



## nathan_h




> Quote:
> Originally Posted by *nickbuol* /forum/post/0
> 
> 
> Yea, I'm thinking that it will be crap. I already have my speakers, and they are even rear ported, so there is sound definitely coming out the back. Crappity crap crap crap...



Well rear ported speakers behind an AT screen would be a poor idea as well.


----------



## nickbuol




> Quote:
> Originally Posted by *nathan_h* /forum/post/21820472
> 
> 
> Well rear ported speakers behind an AT screen would be a poor idea as well.



Really? Why? If the whole screen wall is AT, then why would it matter? It would seem that the only major difference between AT and non-AT screens and walls acoustically would be that the AT setup would have a treated real wall (behind the speakers) and then anything that the AT screen manages to block. In a non-AT setup, I would still have bass traps, but no absorption on the wall (since the screen would be against the drywalled wall). I was planning on a 2.5 foot distance between the real wall and the false wall which should leave a few inches between the front of the speakers and the back of the screen, plus about 10-12 inches between the rear of the speakers and the front of the real wall's treatments.


Not saying you are wrong, just asking for more information please. I have been planning on an AT wall since I started finishing my basement almost 9 months ago. My wife hates my big SVS sub, and my SVS clone sub, so I figured I could go AT with my speakers from my previous theater setup and have a clean front of the theater and hide the subs.


----------



## Eyleron

If the resonant frequency of the port is below the crossover frequency, does the rear port come into play much?


----------



## nickbuol

I am sure that there is still air moving around, but that is an interesting point. Since lower frequencies are what moves the most air (and thus forces it in and out of the ports), the crossover set at the THX recommendation of 80Hz would reduce that. Of course, things like Audyssey or other actual tuning methods may yield a higher or lower crossover is best for sound, but I would wager that it still would be less than a full frequency range sent to the speakers.


----------



## nathan_h




> Quote:
> Originally Posted by *nickbuol* /forum/post/0
> 
> 
> 
> Really? Why? If the whole screen wall is AT, then why would it matter? It would seem that the only major difference between AT and non-AT screens and walls acoustically would be that the AT setup would have a treated real wall (behind the speakers) and then anything that the AT screen manages to block. In a non-AT setup, I would still have bass traps, but no absorption on the wall (since the screen would be against the drywalled wall). I was planning on a 2.5 foot distance between the real wall and the false wall which should leave a few inches between the front of the speakers and the back of the screen, plus about 10-12 inches between the rear of the speakers and the front of the real wall's treatments.
> 
> 
> Not saying you are wrong, just asking for more information please. I have been planning on an AT wall since I started finishing my basement almost 9 months ago. My wife hates my big SVS sub, and my SVS clone sub, so I figured I could go AT with my speakers from my previous theater setup and have a clean front of the theater and hide the subs.



The point above about whether the ports even come in to play given your likely crossover point is a good one, and I agree that if you have lots of space, it's less likely to be an issue, anyway.


----------



## boy711

Hello. I have read through alot of posts in the last couple weeks. My question is specific. I need to know how an environment is affected by a window and open door element. How is sound changed with an open doorway behind the main seat and another in front of the room where the subwoofer lies. How is the bass changed or not? I am going to try and post pictures of my room. Please comment on anything obvious and not so obvious.

The windows are only treated with double layers thick of curtains.




I currently have Onkyo ITB front and center channel and 8" Downward fired Sub, JBL Synthesis side surrounds (bipole), Boston Acoustics Rear surround (bipole). The receiver is a Pioneer Elite VSX-52 and a Toshiba 46" LED back lit display.


I paid $30 for the pro at Ready Acoustic website to review my space and make recommendations. Has anyone used this service???


----------



## GRBoomer

The window is a really good reflector of sound energy, with very little attenuation.


The open door is a perfect absorber of sound for room modes that are peaking at the door location.


----------



## Eyleron




> Quote:
> Originally Posted by *GRBoomer* /forum/post/21833273
> 
> 
> The window is a really good reflector of sound energy, with very little attenuation.
> 
> 
> The open door is a perfect absorber of sound for room modes that are peaking at the door location.



Windows actually pass a lot of sound; they're not a very good way to keep sound out, or in. They're a transmitter & reflector of sound, depending on the frequency.


You're probably thinking of the high frequencies, which it reflects.

A window is a low pass filter. 18mm thick will reflect bass more. 4mm thick will reflect / transmit bass less.
http://www.nrc-cnrc.gc.ca/eng/ibp/ir...igest-240.html 


Not sure if I'd call the open door a perfect absorber. At the lower frequencies where the wavelength is larger than the size of the door, isn't it more of a weakening of the wall, and thus attenuating the peaks and troughs of the modes?


----------



## nathan_h




> Quote:
> Originally Posted by *boy711* /forum/post/21832003
> 
> 
> Hello. I have read through alot of posts in the last couple weeks. My question is specific. I need to know how an environment is affected by a window and open door element. How is sound changed with an open doorway behind the main seat and another in front of the room where the subwoofer lies. How is the bass changed or not? I am going to try and post pictures of my room. Please comment on anything obvious and not so obvious.
> 
> The windows are only treated with double layers thick of curtains.
> 
> 
> 
> 
> I currently have Onkyo ITB front and center channel and 8" Downward fired Sub, JBL Synthesis side surrounds (bipole), Boston Acoustics Rear surround (bipole). The receiver is a Pioneer Elite VSX-52 and a Toshiba 46" LED back lit display.
> 
> 
> I paid $30 for the pro at Ready Acoustic website to review my space and make recommendations. Has anyone used this service???



What did the service tell you?


One question about layout: Why is the TV not on the big open wall? It will be much easier to position the speakers well, and treat reflection points.


----------



## clckwrkorange




> Quote:
> Originally Posted by *nathan_h* /forum/post/21820472
> 
> 
> Well rear ported speakers behind an AT screen would be a poor idea as well.



Couldn't you build a shelving unit on each side of the screen behind the AT material which holds your speakers so the sound doesn't disperse behind the screen wall?


----------



## boy711

The Tv Is in a corner and probably should not be. That was done to save space in the room. All the components are in the closet. The closet door is missing and is located on wall with the couch.


Still waiting on the Real Traps room acoustics service...


Really not sure how the room can be treated. I mean the corners are tight and packed with furiture and/ or speaker locations. I am open to any panel absorber designs that can be effective while maintaing a small footrpint.


The speakers pictured below are supposed to be my new fronts. They are Focal 8" mids and Morel tweeters. The cabinets were made in my garage.


----------



## Nick in Manitou

I originally posted this in the DIY Acoustic Treatment thread, but as it has been inactive for a long time, I don't believe many people saw it. I am posting it here hoping to get some feedback as to any shortcomings there might be in my design...


I have read a lot of the posts on the AT Master thread and since I am not an engineer or really an audiophile, much of what is "discussed" here goes over my head. I think I have picked up the basics and would like some feedback on my plan.


I have an oddly shaped room and hope to improve the basic acoustics by placing some panels in the places usually suggested for calming first reflections and by building some corner base traps.


I am trying to come up with a simple construction plan using OC703 spray glued to some 1/4" plywood with significant cutouts to allow the sound to penetrate through to the void between the back of the OC703 and the wall. All of the edges, front and rear would have drywall corner bead on them to allow for an attractive and impact resistant corner to the acoustically transparent fabric covering for the front and all the sides.


I am not much of an artist, but here is a sketch of what I am thinking of doing:










So, the OC703 would have minimal plywood between it and the space behind it. The sides behind the absorbent material would be as open as possible yet covered with the cloth covering and the edges would be protected by the corner bead. In order to maximize the benefit of the absorber the sides would not be covered by a reflective wooden frame.


Am I headed the correct direction? From what I have read and the examples I have seen, I think so. BUT...I have been known to be pretty thick sometime.


Thanks for your patience.


----------



## LeBon

I think you'll find that a 2' x 4' x 2" thick OC703 board is stiff enough to support itself in a frame like this. I would think you can do without the 1/4" plywood backing, and simply support the OC703 around the edges of the panel


----------



## Nick in Manitou

LeBon, thanks for your response.


The reason for the plywood is to give me something to attach the standoffs to and to be able to leave the sides open so as to not cover them with a reflective (wood) frame.


My impression is that by leaving the sides of the OC703 open and leaving the sides of the air space behind the OC703 open, I would be maximizing the effect I am looking for. Also, the plywood behind the OC703 would be mostly cut away retaining just enough to retain rigidity.


By "simply support the OC703 around the edges of the panel", I am assuming that you mean putting some sort of frame around the perimeter?


Again, thanks for your feedback.


----------



## GRBoomer

The plywood is going to defeat the purpose of having the air gap. You are making something that will have unknown results, that will only lessen the effectiveness. I say drop the plywood from the design.


----------



## LeBon

Many of the absorptive 2x4 wall panels I have seen have a wood frame around them. Acoustimac or ATS Acoustics will sell you the frames ready-made. I wouldn't worry about the frame around the edge.

You can also spray the edges of the OC703 with a urethane or the like to stiffen if you like.


----------



## Nick in Manitou

I think as a result of these responses, I will re-think the design.


I have not actually gotten my hands on the OC703 yet, so I have not played with it yet to see how rigid it is.


Could one use blocks of OC703 itself as standoffs?


I will await the arrival of the material and proceed from there.


Thanks for the feedback!


----------



## myfipie




> Quote:
> Originally Posted by *GRBoomer* /forum/post/21855458
> 
> 
> The plywood is going to defeat the purpose of having the air gap. You are making something that will have unknown results, that will only lessen the effectiveness. I say drop the plywood from the design.



+1.. Also you want the panel to be as open as possible on the sides. Trust me after spending may days in the lab is does make a difference


----------



## boy711

The panels I chose were originally 4" with Roxul. I am going to make them soon. I went with 2" OC 703 for my side wall panels. Just made a 2" frame all around and cut slots in the sides. Picked that up from the forums somewhere







The frames are pine 1x and I bought 4 table cloths 84 x 60" which wrapped the pannels nicely with some to spare. Also spent a couple bucks on internal corner braces and used a nailer to glue and nail the pieces.


The panels look nice and do the job well. I noticed that as a result of slotting the frames the overall weight was decreased significantly.


Overall, the project is worth it but still very expensive for foam and wood panels. I would definitely do this again.


----------



## Nick in Manitou

I appreciate hearing about the fact that keeping the sides open will make very little difference to the overall performance of the panel. I had been under the impression that keeping the sides open would enhance the performance significantly.


Also, not to belabor the point, but it seems I didn't make it clear in my original presentation of the concept for the panels, but I intended to cut away all but a small bit of the plywood...leaving only enough to keep it strong enough to mount the standoffs and hanging method to.









The original concept was to make a panel that would be effective and VERY easy to build (no frame to glue/screw/brace together) and acoustically only just slightly different than hanging just the absorbent material by itself.


It seemed to me that if one left a 1" perimeter of plywood with perhaps a 1" cross member, that there would be very little defeating of the advantages of the absorbent material, and very little construction effort.


Maybe I am still missing the point?


----------



## LeBon

I would think that would work fine. You could probably do without the cross-member, as well.


----------



## boy711

Go to your local Lowes and ask for "Saw Tooth" hanger brackets. I think these brackets are best. for frame style that typically capture the foam panel.


I think that having cut slots in the sides I imagine that sound is being redirected in the form of remaining reflections. Away from the listening position. However, I bet this works better for lower tones in a 4 inch thick trap.???


----------



## boy711

These things are so light!


----------



## ATWindsor

I would like to get some porous absorbers with a print of my choice, does anybody know of a manufacturer that sells products like that? I guess a bass trap with custom print also would be interesting. Any help is appreciated.


----------



## dragonfyr

I believe GIK offers dye sublimation printing suitable for broadband porous absorber panel facing.


----------



## Nick in Manitou

I believe I have seen elsewhere on AVS Forum that there was at least one company that was offering a service whereby you send them a picture and they would print it the size you wanted on AT material. Unfortunately, I don't remember which thread it was on...


---I did a quick search and found this: http://www.avsforum.com/avs-vb/showt...5#post20040455


----------



## CruelInventions

Besides the popularly recommended GIK folks, some links I've had saved for a while (but no direct or indirect experience with them):

http://www.audimutesoundproofing.com...ass-traps.aspx 

http://www.acoustimac.com/index.php/...rt-panels.html 


This next one is a little sketchy in terms of ideal performance from a panel (limited depth options, or so it would appear at first glance):

http://www.msr-inc.com/salon_acoustics/salon.html


----------



## CruelInventions




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21862437
> 
> 
> Actually the issue of open sides is a rather moot issue.
> 
> 
> The additional losses due to edge diffraction are about equivalent to any additional absorptive losses offered by open edges, and the convenience for handling and hanging a frame far out-way any imagined benefit of an unframed panel.



Interesting. I've always liked the more finished look imparted by some of the metal frames I've seen (along the lines of these , for example) but avoided seriously considering given my (apparently) mistaken old view that these would be too detrimental to ideal performance.


----------



## boy711

I have decided to mount the panels floating away from the wall. Are there any methods that will allow for least material and drilling?


----------



## CruelInventions




> Quote:
> But I suspect it will also be a message that is slow to permeate and dispel the world of online 'urban acoustical myths'.... So don't be surprised when you see the topic debated....



Not unexpected. It's audio after all, where no idea ever really falls totally out of favor, no matter how ridiculous.


----------



## mphfrom77

IPhone app messed up...posted in wrong thread. Can't delete. Will be back in the future though.


----------



## ATWindsor

Thanks for all the tips guys! I think i probably will go for the homemade variant, the price is pretty steep for the prefabricated porus absorbers. Which frankly is a pretty simple construction.


----------



## boy711

Good to know that slotting the panels makes no difference. When I make my bass traps I will NOT slot them and save alot of time. However, slotted traps save weight.


My wall absorbers are complete and are spaced from the wall 2". I went the cheap route and used lag shields and 3" screws to hang the panels and used another pair of 3" screws as bumpers for the bottom of the frame.


----------



## boy711

Oh, and still used the sawtooth hangers.


----------



## CarloBadalamenti




> Quote:
> Originally Posted by *nathan_h* /forum/post/21733708
> 
> 
> Every manufacturer seems to have their secret sauce, like RPG and RealTraps using absorption / diffusion combination products, or Auralex no longer publishing specs and test results, though they did at one time, and imply there is science behind their offerings.



Full Disclosure: I am an employee of the company listed in my signature and if I'm overstepping my bounds by posting a link to test data in this message, Mods, please feel free to edit/delete the links or inform me and I will do so.


For the sake of access to information, Auralex _does_ have their performance data listed ( http://www.auralex.com/testdata/ ). It's slightly antiquated though, with all the data being recorded in the 90s.


In the process of expanding our acoustic line last year, we ran 3rd party comparison testing alongside Auralex products and listed the results for both ours and the Auralex products, which we purchased and had tested at the same facility they used for their own data sheets. All the test data for Auralex is from 2011, as is the data for all of our products but one, so if you were looking for more recent performance testing results from them, you can find it here: http://www.foambymail.com/acoustic-f...t-test-results


----------



## audiovideoholic

What would be the best material to put on the ceiling to cover the entire area? The ceiling is already painted almost black but still want something else for accustics.'


something cheap that will help. It doesnt have to be a top performer. And either black/dark grey or can be painted.


----------



## audiovideoholic

double post


----------



## mtbdudex




> Quote:
> Originally Posted by *audiovideoholic* /forum/post/21892209
> 
> 
> What would be the best material to put on the ceiling to cover the entire area? The ceiling is already painted almost black but still want something else for accustics.'
> 
> 
> something cheap that will help. It doesnt have to be a top performer. And either black/dark grey or can be painted.



I see your build thread , Sony VW1000 4k, 13' Scope, and Ten 21 Inch Subs 


Do you have some strategy for acoustics?

Consultated with anyone, or all DIY?

Seems like you've went top notch $$ with the PJ, screen, etc...yet want "something cheap that will help" on the ceiling.


----------



## audiovideoholic




> Quote:
> Originally Posted by *mtbdudex* /forum/post/21893928
> 
> 
> I see your build thread , Sony VW1000 4k, 13' Scope, and Ten 21 Inch Subs
> 
> 
> Do you have some strategy for acoustics?
> 
> Consultated with anyone, or all DIY?
> 
> Seems like you've went top notch $$ with the PJ, screen, etc...yet want "something cheap that will help" on the ceiling.



LOL, yeah dennis provided me with his plans for accustics on all the walls. From what I understand about theaters and his plans is that he only adds ceiling plans if the customer wants them. I originally didnt ask for any and have emailed him about it. I'm just wanting an easy way to have a black material on the ceiling whether it be accustical or just fabric or another material that wont "hurt" what the treatments on the walls are doing. I think the ceiling is the last thing anyone including Dennis is concerned with unless the room "needs" it.


----------



## GRBoomer

The idea with constant directivity waveguides (CD) such as Procella, Pi Speakers and the SEOS thread (in the DIY speaker forum) is that there is much less acoustical energy in the vertical so you do not have a typical high energy short delay reflection bouncing off the ceiling towards you. Yet, you get good, well controlled horizontal dispersion, to create a wide listening sweet spot. With waveguides, you do not have to correct, what's not there. Prevention versus cure.


In fact well defined horizontal control from waveguides also lessens the absolute, blind need for absorption at the first reflection point and starts to muddy the equation to diffusion being more beneficial to preserve the energy content in the room instead of trying to bury it all with fiberglass.


----------



## audiovideoholic

Yeah, thats why I asked Dennis before even considering a material to put up there. Thinking just fabric may be my best bet.


----------



## myfipie




> Quote:
> Originally Posted by *GRBoomer* /forum/post/21896204
> 
> 
> The idea with constant directivity waveguides (CD) such as Procella, Pi Speakers and the SEOS thread (in the DIY speaker forum) is that there is much less acoustical energy in the vertical so you do not have a typical high energy short delay reflection bouncing off the ceiling towards you. Yet, you get good, well controlled horizontal dispersion, to create a wide listening sweet spot. With waveguides, you do not have to correct, what's not there. Prevention versus cure.
> 
> 
> In fact well defined horizontal control from waveguides also lessens the absolute, blind need for absorption at the first reflection point and starts to muddy the equation to diffusion being more beneficial to preserve the energy content in the room instead of trying to bury it all with fiberglass.



I really would invite you to read the following about early reflections before thinking diffusion is the way to go. The point is to hear that is coming out of the speakers not the speakers plus the ceiling reflection.
http://www.gikacoustics.com/news_020209.html


----------



## ahmedreda

First off, My room is 12x20x8.

The side walls are divided into 7x4 sections each covered with a 1" thick fabric frame. The back wall is divided into 4x4 sections.


Initially I had the 8 frames next to each corner filled with 1" OC 703. and the frames other than that had a checker pattern.


Given that configuration my speakers were toed in so that they intersect about 4 feet behind the MLP. If I make them intersect at the MLP they won't sound very good and they tend to hurt my ears at higher volume.


So I had some extra 703 laying around so I went ahead and covered the rest of the back wall with it as well as most of the side walls. The result was horrible. The room sounds very dead and I had to make the speakers point directly at the MLP to get it to sound anything decent. My guess is that before I was just hearing reflection of the two front speakers from the back wall. Now I think I am absorbing too much of the upper mid - high frequencies.


I do have 4 speaker stands each about 30" high for my surrounds that I filled with 5" oc 703. to act as bass traps. They are about 1 foot long and each 2 make a rectangle with the corner. ( I made that configuration up)


2" thickness is out of the question. So before I tear everything up to the way it was, I wonder if someone could give me any ideas.


Here is a link to pictures of my system to make it easier to visualize what I am saying.

http://www.blu-ray.com/community/gal...mber=ahmedreda 


About my system:

Fronts Polk RTI A9, Surrounds RTI A5, Center CSI A6

Denon 4311ci, Emotiva XPA5 + XPA2


----------



## R Harkness

I wasn't sure where to pose this question, but since professionals like Dennis E. visit this thread....


I have tried to create a retractable "black box" effect in my home theater room, using black acoustically transparent curtains that can be pulled along the side and back wall.


My projector is on a lift behind the viewing sofa, nestled in the nook of some bay windows, so in other words there is a bit of room space behind the viewing sofa. You can see photos in this post:

http://www.avsforum.com/avs-vb/showt...8#post18848458 


So now I am going to be pulling an acoustically transparent curtain set behind the viewing sofa, to cut back wall reflections. There will be a cut out in the curtain for the projector to project through.


Sound issues aside: Will this create any difference in terms of heating or cooling in the room? In other words will heat tend to build up more around the projector due to it being curtained off in it's space behind the sofa? Or can I presume air, heat, etc, will transfer through the acoustic material roughly as sound will, and that there will be essentially the same thermal characteristics to the room as before?


Since we are always cautioned about how easily heat is lost through various materials, including windows, I just went into this figuring that heat would transfer pretty easily through pretty thin acoustic material.


(I'm wondering if adding this drape behind the viewing sofa will cause either the projector or people sitting on the sofa to become warmer, faster, compared to when we didn't have the drape behind us).


Thanks,


----------



## R Harkness

Sorry dragonfyr, I guess my post wasn't as clear as I thought.


The "creating a black box to kill back wall reflections" is for light reflections, not sound reflections. Mine is a projection-based home theater but I have light walls and I'm using the black curtains to kill light reflecting from the walls back to the screen (can't do darker walls for various reasons). Behind the viewing sofa is light wall, which is why I'm running a curtain across it. I chose acoustically transparent black material because that curtain is being pulled across my rear FX speakers (I have a 7.0 surround system), and of course I want to still hear my rear speakers.


However, I hadn't put too much thought into the heat issues, if there will be any.


Acoustically it's obviously not ideal - it does deaden the room a bit more. I'm hoping that doing running my AV receiver's Audyssey program with the new curtains in place will get some life back in the sound. I know it's limited and can't fix the changes in sound dispersion brought in the curtains, but I'm hoping it can help somewhat.


(Gawd I hate the spelling of "Audyssey." Trips me up every time...)


----------



## ahmedreda

Thanks for your response. That was pretty helpful. I am planning to try the software you mentioned. In the mean while, I will take the treatment back to the way it was which I liked to a good extent.


I have one more question, Would filling those speaker stand with the 5-6" of 703 do anything for the bass (good or bad)?? They are not in the corner but they kind of form a rectangle with the corner. It is easier to understand by looking at the pictures. I kind of noticed a little better bass but it could be because I am missing all the high end reflections the bass seems more obvious.


Thanks a lot.



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21899217
> 
> 
> Lots of problems.
> 
> 
> First, treatment for specular reflections (behavior above ~250 Hz) should be broadband.
> 
> 
> Otherwise you only EQ the reflections and change the timber of the perceived sound - all while doing nothing to resolve the anomalies created by superposition of high gain reflections.
> 
> 
> And 1" of porous absorption is good for little other than flutter echo.
> 
> 
> Secondly, what should one imagine if the treat the rear sides and back of the room with absorption other than to create a deader space - to the degree that it EQs the reflections and fails to stop the destructive superposition?
> 
> 
> Yes, you can guesstimate as to the polar dispersion of the speakers and you can guesstimate as to the optimal location for reflection control without knowing where the actual early arriving high gain reflections are incident - and simply deaden the room more than necessary in the quest and very possibly miss the actual high gain indirect paths.
> 
> 
> And you can also figure out what acoustic response model you desire - but if you are placing absorption all over the rear and sides its hard to imagine you are interested in a later arriving diffuse soundfield that provides a sense of envelopment or spaciousness!
> 
> 
> But after you figure out what kind of response you like, you can use (free) RoomEQWizard, (along with a calibrated Dayton EMM6 mic from Cross Spectrum and an ART Dual USB Pre mic preamp from B&H Photo for ~$69 delivered along with a mic cable , adapter and an RCA cable), to measure the room modes and adjust the seats forward or back to avoid the nulls, and you can make ETC measurements to identify the actual paths of the actual high gain early arriving reflections and place adequate broadband absorption at those points of boundary incidence and verify their effectiveness.
> 
> 
> You can also determine if you want to control the later arriving reflections with absorption resulting in a 'dead room', or with diffusion, helping to preserve a sense of envelopment and space.
> 
> 
> Depending upon the desired response, the ETC will provide a means to precisely place such absorption or diffusion treatment and will allow you to ascertain the spatial/temporal quality pf the resulting soundfield.


----------



## GRBoomer




> Quote:
> Originally Posted by *myfipie* /forum/post/21897945
> 
> 
> I really would invite you to read the following about early reflections before thinking diffusion is the way to go. The point is to hear that is coming out of the speakers not the speakers plus the ceiling reflection.
> http://www.gikacoustics.com/news_020209.html



I did not say diffusion was the way to go. It is just with better controlled speakers, you may have other options than just trying to kill all the sound with absorption. And you lessen the influence of the ceiling reflection by not throwing energy at it in the first place.


I agree, measure and determine a strategy.


----------



## R Harkness




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21901399
> 
> 
> Oh, so the problem is that the reflections are not 'massive' enough???? LOL!
> 
> In my haste you definitely caught me!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hmm...so we either need to figure out how to dim them, or to enable them to gain some weight... Let me get back to you regarding the latest best practices...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Your post is a veritable ******** of double entendre!!!



Try as I may, I can not make heads or tails of this reply. (Or I'm not taking the right drugs?).


Anyone else have a reply to my question? Thanks.


----------



## localhost127




> Quote:
> Originally Posted by *GRBoomer* /forum/post/21900654
> 
> 
> I did not say diffusion was the way to go. It is just with better controlled speakers, you may have other options than just trying to kill all the sound with absorption. And you lessen the influence of the ceiling reflection by not throwing energy at it in the first place.
> 
> 
> I agree, measure and determine a strategy.



"diffusion" is a very vague term as we use it in these contexts...


does the diffuser offer scattering only or true (flat power response) diffusion? spatial dispersion only? spatial + temporal dispersion? bandwidth of diffuser? minimum seating distance to diffuser (based on design frequency)? angle of incidence when it is mounted on a boundary (as it can alter bandwidth cut-off)? etc...


and in your first statement: _"blind need for absorption at the first reflection point"_ --- bear in mind that large (with respect to wavelength) flat reflectors are more ideal than broadband absorption to redirect the high-gain indirect sparse early arriving reflection away from the listening position and towards the rear wall where it can be diffused and returned to the listening position as a laterally arriving, exponentially decaying diffused sound-field. eg, splayed walls (geometry) can be used for this in an example of a 2ch listening room. if you have rows of seats then it is likely not feasable - but the same goes for diffusion. lots of variables within the requirements... but absorption is most certainly NOT the ideal way to attenuate early arriving high-gain indirect specular reflections -


and there is no "blind placement at first reflection point" either, as one should ideally be measuring with the ETC to identify which boundaries are incident of the high-gain early arriving reflections, and attenuate/treat accordingly - but if one blindly applies broadband absorption at "all first reflection points", without knowing whether any issue exists there in the first place ... then that is a quick way to lead to a highly damped room!! if utilizing broadband absorption, it should be surgically placed only at boundaries incident of such energies as verified with the ETC to limit the amount of broadband absorption within the room. (and now you know why redirection is preferred to absorption) --- that is, unless the design goal is to create a highly damped room!


----------



## sdurani




> Quote:
> Originally Posted by *R Harkness* /forum/post/21899437
> 
> *Sound issues aside*: Will this create any difference in terms of heating or cooling in the room? In other words will heat tend to build up more around the projector due to it being curtained off in it's space behind the sofa? Or can I presume air, heat, etc, will transfer through the acoustic material roughly as sound will, and that there will be essentially the same thermal characteristics to the room as before?



The thermal insulation properties of a single layer of acoustically transparent cloth are likely negligible, so I doubt you'll notice any temperature changes even with the material draped across three walls (left, right, back).


----------



## Brad Horstkotte

But the back "curtain" isn't on the wall, its in front of it, based on the picture, but about a couple feet. The curtain will impede air circulation (heat), so I would expect that area to warm up from the projector, but its still a good sized area, so probably wouldn't be a problem. What side does the projector pull and exhaust air from? Then again, I guess the curtain in the back needn't go all the way to the floor or even ceiling, if you wanted to leave a gap to let air flow.


----------



## R Harkness




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21903195
> 
> 
> If its not acoustical terms its basic English....
> 
> Look up the meaning of a "double entendre".



I know exactly what "double entendre" means. What I don't see is how you find my statements like:

_"The "creating a black box to kill back wall reflections" is for light reflections, not sound reflections. Mine is a projection-based home theater but I have light walls


Mine is a projection-based home theater but I have light walls"_


...To be rich sources of double entendre.







What alternate meaning do they imply?



> Quote:
> Originally Posted by *dragonfyr* /forum/post/21903195
> 
> 
> ...And if you have to explain the joke...



...it's probably not a good joke. Or one should not be in the humor business?


----------



## R Harkness




> Quote:
> Originally Posted by *sdurani* /forum/post/21903622
> 
> 
> The thermal insulation properties of a single layer of acoustically transparent cloth are likely negligible, so I doubt you'll notice any temperature changes even with the material draped across three walls (left, right, back).



Thank you!


If that's the case then my only real worries are alterations in the room acoustic. I do notice them (sounds more dead), but I'll have to see if room EQ can help enough for me to find it acceptable. (This is not a concern with listening to music in the room, since I do not have those curtains in use when simply listening to music, only when watching movies).


----------



## R Harkness




> Quote:
> Originally Posted by *dragonfyr* /forum/post/21903970
> 
> 
> I have already made reference to some of them. If you can't see them even after several having been pointed out, well, then you are unable to identify double entendre.
> 
> 
> I am glad you understand the definition, if not the actual 'thing'. Sorry if the references sailed past you...
> 
> 
> But take a light hearted comment oh so seriously and in so doing call into question the understanding of the term itself as well.



No not serious at all, just wondering what joke I was missing. If it was all a play on "light," well, I guess we have different views on "funny," but no harm.


Thanks,


----------



## dragonfyr

And it just keeps on going...


But hey, when in Rome...


...As if what _I_ found bit bit ironic is dependent upon _others_ 'getting it'.


And we wouldn't even begin to beg the issue as to why a question regarding light reflections and having absolutely nothing to do with acoustics is doing in a thread entailed "ACOUSTICAL TREATMENT MASTER thread"


The fact is there is plenty to smile about, if only in the all too common 'roll the eyes' 'oh brother' online forum manner.


...Next topic.....


----------



## boy711

Here are my bass traps installed.

Again I used tablecloths to cover the OC 703 and also dused two panels for this application
Attachment 243762 

Attachment 243763 

Attachment 243764 


Also have the broadband panels 2 inches off the wall.


Now I am waiting for my 6 channell amp and new home made front chnnel enclosures.


----------



## Elill

Hi all,


I'm looking at some DIY absorber panels. The commercial one I have at home has a membrane under the fabric that is described as _"impact resistant L32 membrane"_. Does anyone know what this might be? or what I could use for it?


Cheers


----------



## nickbuol

The L32 is for exactly what it states, to resist impacts. Those are used many times in high traffic areas (many times commercial/public locations) where the L32 prevents dents or impacts from damaging the panel.


In a home theater, I can't imagine ever needing that. Plus I am sure it would drive the cost up too.


For DIY, there are a number of build options. Some use rigid insulation like Owens Corning OC703, put a frame around it out of wood, metal, whatever, cover it with an acoustical fabric like Guilford of Maine (GOM) RF701, and hang it on their wall/ceiling.


There are other factors, like 2" vs 4" thick for the panel, and yes you will get increased performance out of it if you can leave a gap behind the panel between it and the wall/ceiling. So a 2" thick panel, sticking 2" off of a wall/ceiling surface would do very well.


Of course, there are other absorption that could be done in a room (bass traps, the entire front wall behind our speakers, etc) but you asked about panels.


Hope that helps. Others will probably have additional tips.


----------



## LeBon

Some bass traps also use a sheet of kraft paper or 3-mil plastic film over the front. This reflects higher frequencies, and keeps the bass trap from absorbing them.


----------



## localhost127




> Quote:
> Originally Posted by *LeBon* /forum/post/21917613
> 
> 
> Some bass traps also use a sheet of kraft paper or 3-mil plastic film over the front. This reflects higher frequencies, and keeps the bass trap from absorbing them.



6mil plastic will begin to reflect specular energies ~500hz and up:


----------



## Elill

This is for a flutter echo problem in a living room, so I dont want to use the plastic on the front of it. I thought perhaps the membrane was something special that was firm(ish) and relatively AT (but 500hz and up reflection isn't helpful).


I was thinking I might put a thin layer of felt over the face of the panel before the fabric goes over, just so it is perfectly flat and uniform


----------



## LeBon

If you're using Owens Corning 703 or another hard fiberglas, I have found that a little spray adhesive (like Scotch 77) directly onto the OC works well to hold the fabric (such as GOM FR701). Shouldn't need any intermediate fabric to get a nice-looking finish.


----------



## boy711

3M 777 is messy but absolutely works when applying fabric directly to the panel core.


----------



## localhost127

hopefully not covering the entire porous outer face and possibly clogging the porous holes with the 3M adhesive...could have unexpected results and become reflective to HF content...


----------



## Dennis Erskine




> Quote:
> This is for a flutter echo problem in a living room, so I dont want to use the plastic on the front of it. I thought perhaps the membrane was something special that was firm(ish) and relatively AT (but 500hz and up reflection isn't helpful).



In your case, likely true; however, while the membrane meets a couple of purposes with respect to LF performance, it is also used where additional LF absorption is desired but additional HF absorption would not be beneficial.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21923545
> 
> 
> In your case, likely true; however, while the membrane meets a couple of purposes with respect to LF performance, it is also used where additional LF absorption is desired but additional HF absorption would not be beneficial.



Is there any resource you can point to Dennis that would help me wrap my head around why adding the membrane onto the face of a bass trap helps improve LF absorption?


----------



## Elill




> Quote:
> Originally Posted by *Dennis Erskine* /forum/post/21923545
> 
> 
> In your case, likely true; however, while the membrane meets a couple of purposes with respect to LF performance, it is also used where additional LF absorption is desired but additional HF absorption would not be beneficial.



Thanks Dennis. Yep, LF performance isn't an issue in this instance - no membrane it is.


----------



## Elill




> Quote:
> Originally Posted by *Brad Horstkotte* /forum/post/21923559
> 
> 
> Is there any resource you can point to Dennis that would help me wrap my head around why adding the membrane onto the face of a bass trap helps improve LF absorption?



Refer Toole, and Acoustic Absorbers and Diffusers from Cox and D'Antonio


----------



## nickbuol

OK. I've been searching, and obviously based off of previous posts, been following this thread.


I am planning on building front corner bass traps this weekend. I am stuck on the design/material question that people go 'round and 'round on.


I was originally planning OC703 or equivalent super chunks, then I was reading that the gas flow is more important, and something like R30 pink fluffy with a 34" face (what is that, about 24" for the other 2 sides) would work better for lower bass. If I decide that I can't give up 24" from the corner, maybe that Ultratouch R13 or R19 would be better.


Then elsewhere, I am reading that you need an air gap behind the trap. How does that work with a superchunk? I thought that the point was that they went into the corner?


So here are my goals with the bass traps (in conjunction to other acoustical treatments)

#1) Improve bass response and overall sound in the room.

#2) Provide a low cost, easy to construct bass trap.

#3) Looks are not important as they will be hidden behind a false screen wall.


I have pretty decent construction skills, but since they don't need to look like much, I am going for cost and functionality without being some ridiculous sized beast.


Please help.


(Notes: For now I am going to treat the whole front wall as well per instructions already received in this tread to make it a "dead" end. I will add the bass traps and see if the sound works for me. If not, I will look into FPR panels and/or making the read wall "dead" too. I want to get the big hitters out of the way that don't monkey with the WAF, and hiding this stuff behind the false wall scores big points with the wife just like hiding my SVS subwoofer will.







)


----------



## cgott42

Please help, I'm looking to add acoustical treatment to my HT.

I've attached a google sketch up (and .jpg) of my HT Room to scale.


I hate to leech (see below I've done some research and am stuck) but I've already put so much time into the creation of the room (i.e. away from wife/work/family/etc) that if I start a new "project" to get to really know sound acoustics, I'll "get in trouble" - so if someone can please look at my measurements and make clear/detailed recommendations for panels to add (where and what) and Bass traps


(orange box in middle is a couch (not actually orange))
*Total Budget* for this = ~$500 ($750 if really worth it)


============================================================ =====================================


Currently I have the following DIY info which I might fall back on
http://www.avsforum.com/avs-vb/showt...8#post21530858 


Details :
*room dimensions* are: W= 10'3" L= 20'1" H=6'7" (note the front (part with black side wall) width of the room is 10'3, and the back (part with maroon side wall) is 9'8" wide
*Floor* is laminate w/ 7'8' area rug in front
*Ceiling* is DW+GG sandwich
*Front wall and opposite side all* (i.e. the wall you see in the pic) are 4layers of DW w/ Green Glue
_Note_ -Other than about 2' from the floor and a few inches from the ceiling - the front wall is entirely the screen. Is so, does it need panels behind it?
*Rear wall* is cement with 2 shelves going lengthwise and the 2 rear speakers sit there.
*side wall closest to you* in pic (i.e. not shown) is cement w/a single piece of DW (hanging on a 2x3) in front of it

Speakers:cylinder sub woofer (SVS CS-29+) in middle/side of room.

equip = Klipsch RF-82II fronts, RF-64II center, RF 62 surrounds (only one is shown), 2 Mirage OMD-5 rear surround (not shown)

*My research to date:*

I've gone through the 1st 5 pages of this thread,

and have read through 1a-d) and 2a-b) of
http://www.gearslutz.com/board/studi...look-here.html and realize that I'm not going to be able to give the time to have a "pro" job done,
 

 

HT_Room2.zip 105.5009765625k . file


----------



## nezff

I was wondering if you guys could help with possible placement of bass traps. I'm wondering if I need them in corners, where walls meet ceilings etc..


----------



## pepar

All modes are present in the corners, so that is always a good place.


Jeff


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/0
> 
> 
> All modes are present in the corners, so that is always a good place.
> 
> 
> Jeff



Jeff, I have angled ceiling or walls, should I hit those also?


I have two doors in the back corners also, so that might be a challenge.


----------



## pepar

With your non-square space I don't know enough to answer confidently one way or another.


Have you done any measuring? That will tell you if you need them at all. Then you can go from there.


Jeff


----------



## nezff

i dont really have any measuring equipment other than my galaxy spl meter. I have played with sub placement all over the room. It always turns out that the subs end up sounding more prounounced in the ugliest places.


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/21997967
> 
> 
> i dont really have any measuring equipment other than my galaxy spl meter. I have played with sub placement all over the room. It always turns out that the subs end up sounding more prounounced in the ugliest places.


----------



## CaliCool

Hello guys!


Hired an architect to do my entertainment room's (not dedicated theater) sound acoustic design.


Room's 3.8m width now and 7m length.


Here's what he came up with:


Metal framing on both sides (and edge of the projector side) with rockwool inside and gypsum board as the final layer.


How effective will rockwool be underneath gypsum boards in terms of helping the room acoustic?


Thank you!


----------



## erkq




> Quote:
> Originally Posted by *CaliCool* /forum/post/22019715
> 
> 
> Hello guys!
> 
> 
> Hired an architect to do my entertainment room's (not dedicated theater) sound acoustic design.
> 
> 
> Room's 3.8m width now and 7m length.
> 
> 
> Here's what he came up with:
> 
> 
> Metal framing on both sides (and edge of the projector side) with rockwool inside and gypsum board as the final layer.
> 
> 
> How effective will rockwool be underneath gypsum boards in terms of helping the room acoustic?
> 
> 
> Thank you!



That's just drywall, right? That won't do anything. Perhaps the rockwool will help sound isolation from the rest of the house more than regular insulation, but not much. And regular insulation isn't worth much to start, perhaps an added 3db of attenuation over an open void in the wall. As far as having drywall as the final layer in the media room... that's what it will sound like... drywall.


----------



## Digital_Chris

Sorry for posting this, but I'm kind of in a stump. I'm looking to tame a huge peak followed by a huge dip at my rear seating location without moving subs or seating position. It's been recommended that adding filler subs will bring up the dip but I feel that taming the peak is more important. If I tame the peak via EQ, I will then aquire a huge dip at my front seats. This is why I feel that some sort of treatment will be the recommended solution.


The room is small (18 x 10 x 7) so I don't have mega room for treatment, I already installed 36" faced super chunks in the rear corners but no room in the front corners for the same treatment. I have my whole back wall that I'm willing to work with (roughly 4ft from rear seat back to wall). The superchunks unfortunately didn't help much except with the ringing.


Aagin, I'm sorry for asking, I feel bad that I keep bring up the same issues hoping that someone has a different answer, I almost don't want to hit "submit" even though this forum is here to help me










Please take it easy on me without too much technical wording


----------



## nickbuol




> Quote:
> Originally Posted by *erkq* /forum/post/22019751
> 
> 
> That's just drywall, right? That won't do anything. Perhaps the rockwool will help sound isolation from the rest of the house more than regular insulation, but not much. And regular insulation isn't worth much to start, perhaps an added 3db of attenuation over an open void in the wall. As far as having drywall as the final layer in the media room... that's what it will sound like... drywall.



Agreed. You won't really see any great benefit at all. Probably not even noticeable without some way to test what it would have sounded without the rockwool. The room inside will still be very "live", and whatever inherent internal acoustical issues you have without the rockwool will still be there when you are done. You might get a touch of sound absorption as it passes through the normally void cavity between the two sides of the same wall, but the fact that the whole wall is connected to itself (drywall inside the room attached to a stud, wood or metal doesn't matter a whole lot, and then connected to the drywall outside the room) means that sound will just transfer right through that wall anyway. Look up "double stud wall" or "staggered stud wall" Those help to "decouple" the inside of the room from the outside. Put your rockwool in the cavities in one of those (just one side of a double stud wall or staggered stud wall so that the rockwool itself doesn't "connect", called couple, the drywall sides again, and you will have a decent core to some sound proofing that you can build off of. Then add more mass (a second layer of drywall inside the room, and the thicker those layers, like 5/8" vs regular 1/2" sheetrock) the better. Put some green glue between the 2 layers, and you will really be doing well. Again, for sound proofing.


None of that helps with in room acoustics. Acoustics as you are saying it (not that you meant it that way) should deal with the sound quality inside the room. Acoustical treatments in that aspect happen AFTER the room is done. Soundproofing is what the designer sounds like he is working towards since it is the room itself that he is working on, and for what he is recommending, you might as well not pay the extra $$ for the rockwool or anything beyond regular construction because, like I said, you won't notice much of a difference at all.


So if you don't care about sound escaping or entering the area, focus on real acoustical treatments INSIDE the room such as bass traps, first point reflection panels, etc. This will clean up the quality of the sound quite a bit, of course in a non-dedicated room, you need to take some care to get things to look good too.


If you want to improve the sound in the room for the least amount of money, have it constructed as the rest of the house is, and spend the money on some decent treatments. This will still be a lot cheaper than the cost of the extra thick walls, rockwool for in the walls, the thicker and double layered drywall, GreenGlue, etc. Plus, those only really help if you have an enclosed space and a nice heavy door to close it all off.


I went for the soundproofing and acoustical treatments for my room that is (almost) finished and absolutely LOVE the results. I can go in the room, shut the door, and if I don't watch a movie, or put on some music, it is just so nice and quiet in there. Great for power naps!










Let us know what your goal is, and people will chime in. Some of the above is just my opinion and others will say that you need to do soundproofing to improve the sound in the room (which IS true), but if you have open paths for sound to escape, then it, in my opinion, isn't worth the cost/effort to end up with a flawed design. Sort of like buying a beat up but expensive sports car and only driving it a couple of blocks at 20 MPH to and from work. You don't get to utilize the performance under the hood, and since it is beat up, it isn't pretty to look at either (like the soundproofing - you can't see it, so people don't even appreciate the effort/cost of it)...


----------



## avted




> Quote:
> Originally Posted by *Digital_Chris* /forum/post/0
> 
> 
> Sorry for posting this, but I'm kind of in a stump. I'm looking to tame a huge peak followed by a huge dip at my rear seating location without moving subs or seating position. It's been recommended that adding filler subs will bring up the dip but I feel that taming the peak is more important. If I tame the peak via EQ, I will then aquire a huge dip at my front seats. This is why I feel that some sort of treatment will be the recommended solution.
> 
> 
> The room is small (18 x 10 x 7) so I don't have mega room for treatment, I already installed 36" faced super chunks in the rear corners but no room in the front corners for the same treatment. I have my whole back wall that I'm willing to work with (roughly 4ft from rear seat back to wall). The superchunks unfortunately didn't help much except with the ringing.
> 
> 
> Aagin, I'm sorry for asking, I feel bad that I keep bring up the same issues hoping that someone has a different answer, I almost don't want to hit "submit" even though this forum is here to help me
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Please take it easy on me without too much technical wording



You might benefit from some kind of tuned absorbers -- like membrane/panel absorbers or helmholtz based absorbers. They are more effective for narrower frequency bands for a given size than insulation. Lots of tips and plans here and online for how to design and construct them.


----------



## CaliCool

Thanks for the info guys! Really informative!


Well... That's a bummer if it won't help. I trusted his design since I thought that gypsum board as the final layer will help in room acoustics. What it'll do it seems is just sound proofing the room?


My ultimate goal is to have better room acoustics... as in better sound quality inside the room. Sound passing out of it is not an issue.


If you guys have time... Can you kindly check on my attachments? I would greatly appreciate it.


----------



## Brad Horstkotte

Ouch, that is a LOT of reflective surface, between the drywall, cement, plywood, glass, and hardwood floor.


----------



## CaliCool

I'll put heavy drapes on all glasses.

Area rug on the floor.


----------



## CaliCool

Guys. Sad thing is I already bought the Rockwool. :-( How can I put it to good use?


----------



## HopefulFred




> Quote:
> Originally Posted by *CaliCool* /forum/post/22023138
> 
> 
> I'll put heavy drapes on all glasses.
> 
> Area rug on the floor.



And that may help with clarity issues in the highest frequency ranges (depending on location and types). That will leave most of the most important frequency ranges (speech, most music) untreated aside from the two or four "acoustic panels" indicated in the drawings. It's tough to suggest what specifically would be a better plan (I am not a professional - not even an experienced hobbyist), but that looks to me like a recipe for problems... not to mention bass...


I'm also a little dubious about the speaker locations. The front speaker locations aren't specified, but I'll assume they will go on shelves below the screen. Especially in that context, I am confused by the placement of the surrounds - I want them out of the corners and down from the ceiling.


As long as you're amenable to adding more "acoustic panels" (whatever that is, specifically) at a later time - hopefully after determining what acoustic problems there are in the room - then the speaker positions are my only objection to those plans.


----------



## HopefulFred

The rockwool can be used to build "acoustic panels" that can absorb the sound the would otherwise reflect off the walls and interfere with your ability to hear the speakers clearly.


----------



## nathan_h




> Quote:
> Originally Posted by *CaliCool* /forum/post/0
> 
> 
> Thanks for the info guys! Really informative!
> 
> 
> Well... That's a bummer if it won't help. I trusted his design since I thought that gypsum board as the final layer will help in room acoustics. What it'll do it seems is just sound proofing the room?
> 
> 
> My ultimate goal is to have better room acoustics... as in better sound quality inside the room. Sound passing out of it is not an issue.
> 
> 
> If you guys have time... Can you kindly check on my attachments? I would greatly appreciate it.



That looks like a cool room, but there is essentially no acoustic design in those plans.


----------



## CaliCool

Thank you nathan for the compliment. I helped with the room design.


I'm just a hobbyist but I'm entirely new to the room acoustic scene (which now seems bigger than video!) Thankfully, there's AVSFORUM to help me.


I talked to him and raised my concerns. He insisted that since the room will essentially be double-walled, there will be an effect in room acoustic. He even stated that Rockwool (ROXUL) serves double purpose in the form of soundproofing and room acoustics.


Don't worry guys though. I know that the plan has many reflections, but I won't leave it that way. I may add more Acoustic Panels if you guys advice it so. Also, an area rug will definitely be there in the absence of a carpet. All windows and sliding doors will also have draperies.


He told me that since we downgraded the budget... we went from


1) Rockwool + Padded Fabric

2) Echo Stop on the Ceiling

3) Carpets on the floor


To...


1) Rockwool + Gypsum Board

2) Acoustic Panel

3) Drapes and Area Rug


Question... Will it have a great effect on Acoustics? The way he designed the room?


As I've said, already bought Rockwool but I haven't given the metal framing a go yet... plus the gypsum boards.


And here I thought that gypsum board is better for sound acoustics.


EDIT: Forgot to note that the positions of the speakers are my responsibility. So its not by any means final. I've decided to put it high because my surrounds are going to be satellites only. Plus I've followed the THX lay out. The fronts are going to be floorstanding speakers, 90 degrees angled to the main listening position.


----------



## nickbuol

I will be blunt... That guy doesn't seem to know what the heck he is talking about. It doesn't surprise me and is more common than you would think. Don't get into an argument with the guy since he is working on your house and you don't want to tick him off. The drywallers here told me that GreenGlue wouldn't work, and that I should fill the wall cavities with insulation (instead of one side of the staggered wall and leaving the other side for an air gap), or that thin curtains would help against a window reflection, etc. The guy thought that he knew a lot and wanted to debate it, but my room results prove that he was wrong.


Drywall is very reflective and doesn't do anything in a single layer form to help really anything. Adding more or building a room inside a room is sound proofing (a small piece of it), but NOT helping with the sound inside the room.


As for the other pieces, sure they will help. Just do NOT put the Rockwool inside the walls. If the guy demands to put something in there, have him put something cheaper in there. It will absorb some frequencies, but not much. Save the Rockwool for corner bass traps or something. You will want to cover as much of the surface area that you can and still be aesthetically pleasing. If using drapes, you will need some good fabric there that will cost more. An area rug is really only treating a small amount of one of the major surface areas in the room. It is also thinner than a carpet and pad. Acoustical panels for first reflection points will be more and more important as there really isn't a lot of treatments in the plan for acoustics. These will help to reduce some of the echo/muddiness from your speakers.


I know it sounds like I am being a big downer, but I just want to help you be realistic. You CAN do a lot without spending a fortune, but the tricks are 1) glass is one of your enemies. Glass doors and windows have been known to be immune to some basic acoustical treatments. 2) reflections are your enemy too, obviously. My latest build gave me a room with so much echo that if you tried to talk to someone in there, it was next to impossible due to SO much echo. This was resolved by a good carpet with a thick pad, furniture, and covering the front wall with what comes to be sort of like a giant acoustical panel. 3) Bass likes to boom in the corners. A fun thing I did was I would talk to someone in the room, and then start walking towards one of the corners. Without me doing anything different, my voice would sound deeper and deeper the closer I got to the corner. People thought that I was faking it, but I wasn't. I put bass traps in the front 2 corners, and it resolved the boomy voice (and bass) in the front, and in the back 2 corners, my voice doesn't start sounding deeper until I get within maybe 6-8 inches of the corner. A LOT better than 4-5 feet from the corner.


Remember acoustical treatments INSIDE the room make the sound better. Once you hit the room itself (hard surface), doing anything there or "outward" deals with soundproofing. They are NOT the same thing. (I think that YOU get this now, but your designer/builder person doesn't)...



Stick around and keep firing off your questions. I learned SO much from this thread, but there is SO much contained in the 296 pages that it can be hard to find exactly what you want or need. So just ask away.


----------



## CaliCool

Thank you nick for a solid, solid post. I'm with you on this one. I'm not closed-minded anyway... and I don't mind if people are blunt in pointing out where we have gone wrong.


I don't own the house. My father does. And he has given me the whole second floor to play with but ultimately that room (Entertainment Room) will house my video and audio equipment. One thing that I didn't touch is the windows, because from the outside the Entertainment Room is visible across the street and our architect created a good exterior enough for me to rule removing the windows out.


What additional treatments do I need to do? My ceiling is bare... As in NADA. Do I need diffusers? Will it greatly help?


Talked to him again. Told me to canvass acoustic panels... Something like .6mx.6m so we can add a lot.


EDIT: Can I do it like this?


Continue the rockwool inside (since I bought truck load of it already) and then put holes on the Gypsum boards? That way the sound will be absorbed by the rockwool? In our office, our ceiling has gypsum board with lots of holes for room acoustics.


----------



## nezff

If you don't treat the inside of the room, you will have reflections from the drywall. Putting insulation inside the wall IS NOT doing anything.


Acoustic panels and bass traps is the only way.


----------



## nickbuol




> Quote:
> Originally Posted by *nezff* /forum/post/22024123
> 
> 
> If you don't treat the inside of the room, you will have reflections from the drywall. Putting insulation inside the wall IS NOT doing anything.
> 
> 
> Acoustic panels and bass traps is the only way.



+100


Plus, drilling holes in drywall:

1) makes a huge mess

2) takes a long time

3) greatly reduces the structural ability of the drywall

4) would need to be covered by something as it would look just silly










For the ceiling, you might see a diffuser in an audio only room, but rarely will see something in home theaters. Not saying that they don't exist, but usually you want to absorb the reflecting sound and not scatter it all around.


I would look at creating some corner bass traps and acoustical panels using some of the rockwool. It isn't super rigid, but people have done it. That will yield the best results in my opinion vs. diffusers or a bazillion drilled holes into drywall (yuck. I can taste the dust now.)


If you bought a truckload of the rockwool, then I would check on the return-ability of it. I mean, if it really isn't going to help you in the walls, then why use it. Even if there is a trucking and return fee, at least you would have some money back.


Just a thought that is worth checking in to.


Keep the questions and ideas coming. We won't shoot them *all* down.


----------



## myfipie




> Quote:
> Originally Posted by *pepar* /forum/post/21996252
> 
> 
> All modes are present in the corners, so that is always a good place.
> 
> 
> Jeff



Plus one.. 90 degree corners are generally best so I would start with those. Don't forget that even floor to wall corners around the room is a great place also. In fact if you are in a basement with a concrete floor it could be the best place to start.


----------



## kromkamp

CaliCool, you seem like perhaps the ideal candidate for the Pro Theater design service offered here - I suggest you contact them and discuss your situation. Make sure to be up front with your budget for treatments etc.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *CaliCool* /forum/post/22023918
> 
> 
> In our office, our ceiling has gypsum board with lots of holes for room acoustics.



The target frequencies for an office ceiling are a whole lot different than a theater room. You can't compare the two.


----------



## CaliCool

I would love to avail the Pro Theater Design, but I live in the Philippines. So that seems like a no-no as of now.


Truth be told, the audio video services offered by "professionals" here are lacking, and we are often left with over-priced services or just DIY methods.


I'll shop for Acoustical Panels. Can you guys suggest ideal positioning? How much do I need? I'll also look for bass traps today.


----------



## Peter M

Don't rule out using a US based designer. Many of us have rooms which were designed from afar ... AVS and email are wonderful things !


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *CaliCool* /forum/post/22027608
> 
> 
> I would love to avail the Pro Theater Design, but I live in the Philippines. So that seems like a no-no as of now.
> 
> 
> Truth be told, the audio video services offered by "professionals" here are lacking, and we are often left with over-priced services or just DIY methods.
> 
> 
> I'll shop for Acoustical Panels. Can you guys suggest ideal positioning? How much do I need? I'll also look for bass traps today.



Why would living in the Phillipines preclude you from taking advantage of the layout service? As far as I know, they have serviced clients all over the world. Why would you say the services are lacking?







Also, placing panels is precisely what the layout provides.


----------



## Peter M

Shawn,


I think he meant pro services in the Philippines are lacking !


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Peter M* /forum/post/22027915
> 
> 
> Shawn,
> 
> 
> I think he meant pro services in the Philippines are lacking !



Ahhhh! Gotcha!


----------



## myfipie




> Quote:
> How effective will rockwool be underneath gypsum boards in terms of helping the room acoustic?



As others have pointed out the person did not address any of the room acoustics. If you want to DIY it then you could use the following as a guide for set up. Basically you want to focus on bass trapping in corners and early reflection points. Diffusion can also be used to keep life within the room.
http://www.gikacoustics.com/room_setup.php


----------



## kromkamp




> Quote:
> Originally Posted by *CaliCool* /forum/post/22027608
> 
> 
> I would love to avail the Pro Theater Design, but I live in the Philippines. So that seems like a no-no as of now.



The Pro Theater Design service offered here is a virtual consultation and layout design, not in-person.


----------



## rthompson10

Hello,


MY theater is open to the rest of the basement- half wall with aisles at the rear. Speakers are all in-wall triads, including the front 3, with the center speaker behing the screen- screen is 3" from wall. does it make any sense to do any treatments for sound on front wall- and if yes- what? given its open to room


Robert


----------



## willscam




> Quote:
> Originally Posted by *rthompson10* /forum/post/22043462
> 
> 
> Hello,
> 
> 
> MY theater is open to the rest of the basement- half wall with aisles at the rear. Speakers are all in-wall triads, including the front 3, with the center speaker behing the screen- screen is 3" from wall. does it make any sense to do any treatments for sound on front wall- and if yes- what? given its open to room
> 
> 
> Robert



Well, since none of the experts answered you, I'll give you my opinion. In your situation, I don't see the need for any front wall treatment. To my understanding, in-wall speakers don't benefit much from treatment around them. They don't have SBIR issues since they're flush with the wall. Sidewalls might be a different story. You could try to contact Triad and see what they suggest.


----------



## nickbuol

My opinion is similar that treating the surface around an in-wall doesn't seem to be as helpful as those that aren't in-wall, unless your room as a whole is too "live" for your tastes. Even then, I would look at other treatment areas first.


Of course, corner bass traps up front are still a good idea.


Would you get some benefit from treating the front wall? Absolutely. I just would think that you might get better bang for your buck with first point reflections. After all, your front sound stage speakers are generally more "directional" than the surrounds as well as more powerful (or at least output at higher levels in most setups). I would worry about the sound that they are sending out and making that as clean and crisp as possible with FPR panels. In a non-in-wall setup, where sound can come out of front speaker rear ports, or general resonance of the speaker cabinet is more important to clean up.


The best scenario would be to put in bass traps, FPR panels, and treat the front wall regardless of in-wall or not. You would get what is generally considered to be the top 3 "bang for your buck" treatments.


----------



## sdurani




> Quote:
> Originally Posted by *rthompson10* /forum/post/22043462
> 
> 
> ...center speaker behing the screen- screen is 3" from wall. does it make any sense to do any treatments for sound on front wall- and if yes- what?



Even in this day and age of surround sound, the front soundstage remains critical; that's where your attention will be focused, whether watching a movie or listening to music.


In order for you to hear a seamless soundstage, your brain tries to create phantom imaging between your front speakers. And while your brain is doing that, the last thing you need is surround information coming at you from that same direction, muddying the imaging up front.


With that in mind, I think it's worth putting some absorbtion on the front walls, especially at the reflection points of your surround speakers. Behind the screen, you can only use 3" thick material, so go with rigid fiberglass (OC703 or OC705) and remember to cut around your in-wall centre speaker.


----------



## CaliCool




> Quote:
> Originally Posted by *CaliCool* /forum/post/22022591
> 
> 
> Thanks for the info guys! Really informative!
> 
> 
> Well... That's a bummer if it won't help. I trusted his design since I thought that gypsum board as the final layer will help in room acoustics. What it'll do it seems is just sound proofing the room?
> 
> 
> My ultimate goal is to have better room acoustics... as in better sound quality inside the room. Sound passing out of it is not an issue.
> 
> 
> If you guys have time... Can you kindly check on my attachments? I would greatly appreciate it.



Sorry for bumping this one but can you guys help me with the speaker positioning? Are my positions OK? Thank you!


----------



## kertofer




> Quote:
> Originally Posted by *sdurani* /forum/post/22066089
> 
> 
> Even in this day and age of surround sound, the front soundstage remains critical; that's where your attention will be focused, whether watching a movie or listening to music.
> 
> 
> In order for you to hear a seamless soundstage, your brain tries to create phantom imaging between your front speakers. And while your brain is doing that, the last thing you need is surround information coming at you from that same direction, muddying the imaging up front.
> 
> 
> With that in mind, I think it's worth putting some absorbtion on the front walls, especially at the reflection points of your surround speakers. Behind the screen, you can only use 3" thick material, so go with rigid fiberglass (OC703 or OC705) and remember to cut around your in-wall centre speaker.



OK, so I have been thinking about my front wall and am wondering something. Right now, behind my screen, I have a thick curtain hung across the entire wall. Should I put insulation behind that curtain? If so how much should go across? Should I put OC703 coating that whole wall to essentially totally deaden it?


I currently have bass traps in my corners and OC703 2" with 2" buffer style panels hung at my 1st reflection points along the side walls. Just doing that made an unbelievable difference, so I think I am at the point of minor returns, but I still think I need to do SOMETHING along my front wall and the back, just not sure what.


----------



## nezff

quick question. How are you guys hanging your bass traps where the wall meets the ceiling? Im thinking some metal string like hanging a picture.


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/22066796
> 
> 
> quick question. How are you guys hanging your bass traps where the wall meets the ceiling? Im thinking some metal string like hanging a picture.



Quick thought here ... if you are "hanging" a bass trap it may not be big enough.


Jeff


----------



## willscam

I hung mine.











I used a plastic "wildlife" netting that's used to protect your garden from critters. It's made of plastic. I used alot of staples to adhere it to the ceiling and wall.











I started by using string and netting, but found the string to be unnecessary and bothersome.


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/22066856
> 
> 
> Quick thought here ... if you are "hanging" a bass trap it may not be big enough.
> 
> 
> Jeff



its 44.5 tall, 2 foot wide and 4 inches thick. Its a corner mount so it will look flush.



similar to this


----------



## sdurani




> Quote:
> Originally Posted by *kertofer* /forum/post/22066595
> 
> 
> Should I put insulation behind that curtain? If so how much should go across? Should I put OC703 coating that whole wall to essentially totally deaden it?



I would put about 4-6 inches of OC703 behind the curtain, spaced a few inches off the wall if possible. If that's too thick aesthetically (makes the curtain bulge too much), then do at least 3" of material spaced 3" from the wall. You can deaden the whole wall if you like, but I would cover at least the middle 40 degrees (±20° from centre).


----------



## kertofer

Thanks sdurani, now my question here is probably very subjective, but is that going to be a minor change in the rooms sound quality or should I expect a major change from this?


Also, what do most people do along the rear theater wall? I was thinking of putting a couple of panels similar to what I have along my side walls back there at my main reflection points, but I don't want to over deaden my room.


----------



## sdurani




> Quote:
> Originally Posted by *kertofer* /forum/post/22067273
> 
> 
> Thanks sdurani, now my question here is probably very subjective, but is that going to be a minor change in the rooms sound quality or should I expect a major change from this?



Depends on usage (surround or stereo), speaker dispersion, the room, your hearing, etc. Like you said, very subjective. On my set-up, imaging became clearer and more detailed, with greater separation between the front soundstage and surround field.


----------



## FOH

I've used netting, fishing line, and "aircraft" cable. Whatever works, as I've got a cool system to facilitate easy experimentation, i.e.; removal and addition of panels.


You can always get it there, and then trim it out with Velcro attached, jumbo speaker grill style covers. Thus maintaining an acceptable visual aesthetic if warranted.


------



> Quote:
> should I expect a major change from this?



If you treat an essentially untreated front wall, the result would be significant. Subjective, absolutely, but certainly significant.



Good luck


----------



## kertofer

Just for clarity, my main usage is a theater for movies, so surround. I have my fronts and center slightly below my screen so the stage is slightly low.


FOH, I would be interested in hearing more about your wall and how you add and remove panels with ease?


----------



## myfipie




> Quote:
> Originally Posted by *nezff* /forum/post/22066796
> 
> 
> quick question. How are you guys hanging your bass traps where the wall meets the ceiling? Im thinking some metal string like hanging a picture.



That may work, but it is just like hanging a panel in the wall to wall corner. Attach to ceiling and wall.


----------



## nezff

thanks Glenn.


----------



## wingnut4772

I treated my open room with Real Traps. Mostly to tame brightness as my bass response is pretty good. Since it is a multipurpose room I am limited with room treatment possibilities but I was wondering if anyone here has a similar room and tried treatments plus an EQ like Audyssey XT32? The Real Traps have helped. Will the Audyssey make any further improvements?


----------



## nezff

xt32 is wonderful. The pro kit adds more also.


----------



## pepar




> Quote:
> Originally Posted by *nezff* /forum/post/22066946
> 
> 
> its 44.5 tall, 2 foot wide and 4 inches thick. Its a corner mount so it will look flush.
> 
> 
> 
> similar to this



Ahh, and you probably have a few of them. For some reason I was thinking of just one trap.










Jeff


----------



## wingnut4772




> Quote:
> Originally Posted by *nezff* /forum/post/0
> 
> 
> xt32 is wonderful. The pro kit adds more also.



Cool. Do you have a similar room ?


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/22071986
> 
> 
> Ahh, and you probably have a few of them. For some reason I was thinking of just one trap.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff



I have two of them right now. They are the same size. They also have slanted sides to sit in the corner of walls or ceiling/walls. My plan was to put them at the end of my small ceiling where the wall meets it. I have slanted walls, so not much 90 degree angles.


----------



## wingnut4772




> Quote:
> Originally Posted by *nezff* /forum/post/0
> 
> 
> 
> its 44.5 tall, 2 foot wide and 4 inches thick. Its a corner mount so it will look flush.
> 
> 
> similar to this



Hey. I have a few of these in the attic just sitting around. Let me know if you need any more. I have at least 2 I was gonna put on Audiogon.


----------



## nezff




> Quote:
> Originally Posted by *wingnut4772* /forum/post/22071990
> 
> 
> Cool. Do you have a similar room ?



I have a more dedicated room. Its in my sig. I have a thread.


----------



## wingnut4772




> Quote:
> Originally Posted by *nezff* /forum/post/0
> 
> 
> 
> I have a more dedicated room. Its in my sig. I have a thread.



Ahhh ok. I'm on the iPad. Didn't catch it. Thanks.


----------



## CaliCool

Question.


How high do I need to hang my Acoustic Panels on the side? I have a .318m x 1.2m panel... four of them... Obviously not the biggest panels around. Do I hang them low enough (ear level) or hanging them higher would be ok? (FOr aesthetic purposes)


----------



## FOH




> Quote:
> Originally Posted by *CaliCool* /forum/post/22075325
> 
> 
> Question.
> 
> 
> How high do I need to hang my Acoustic Panels on the side? I have a .318m x 1.2m panel... four of them... Obviously not the biggest panels around. Do I hang them low enough (ear level) or hanging them higher would be ok? (FOr aesthetic purposes)



What are you wanting to achieve with these panels?


Do you have any pics/diagrams of your room's configuration?


----------



## myfipie




> Quote:
> Originally Posted by *CaliCool* /forum/post/22075325
> 
> 
> Question.
> 
> 
> How high do I need to hang my Acoustic Panels on the side? I have a .318m x 1.2m panel... four of them... Obviously not the biggest panels around. Do I hang them low enough (ear level) or hanging them higher would be ok? (FOr aesthetic purposes)



If they are going in the early reflection points then they need to go on the wall to cover the area between where you sit and the speaker. You can use a mirror to figure out where that spot is.
http://www.gikacoustics.com/news_020209.html 


If bass traps for corners then it really does not matter. The corner picks up bass through out it.


----------



## CaliCool

Thanks for all the help.


Seems like I still have a long way to go with regards to improving my room acoustic. But I'm not going to give up.


My problem right now is the reflection to the ceiling... and how much it will affect my overall acoustic. I may have a problem with DAF (Dad Approval Factor) if I put more panels on the ceiling.


The rug's definitely going to be there to avoid the floor reflection.


Plus drapes over the windows. (Black out curtains)


Then at the moment two panels on the right and two panels on the left.


At least I know that what I'll do will have a MAJOR effect acoustically.


----------



## myfipie

You can only do what you can do, which is better then nothing.


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/22066856
> 
> 
> Quick thought here ... if you are "hanging" a bass trap it may not be big enough.
> 
> 
> Jeff



got it up.


(more pics of it in my sig)


----------



## pepar

How does it sound?


----------



## nezff




> Quote:
> Originally Posted by *pepar* /forum/post/22085375
> 
> 
> How does it sound?



havent had a chance to listen yet.


----------



## nick_danger

Hello all,


I've got a question regarding floor treatment on a basement slab.


I haven't read all 9,000 posts in this thread, but I feel like I've read the ones that matter. I have a pretty good handle on basic acoustic principles and sound proofing versus treatment. I haven't begun construction of my home theater yet - I just have all the hardware in place right now. My basement is set up in thirds - typical 50s-era rambler. Laundry/bathroom on one side, furnace/utility on the other, "finished" room in the center (~13x26x8). It's certainly not finished to our liking, so we'll be starting over from scratch at a future date once we finish some other projects.


My question revolves around how to treat the floor. I don't have the luxury of a 9-10' ceiling, so the treatment needs to be thin enough to not adversely affect the seating riser and mounted projector (I will probably end up making some concessions in that regard). I don't want it to feel claustrophobic, but short of buying a new house I'm not sure I can avoid it...


What's the best way to deal with the reflective nature of the slab? 2x4 framed subfloor filled with insulation with pad/carpet over? Just a pad/carpet over the slab itself? What about the corners (floor/wall edges)?


Thanks.


----------



## Irv Kelman




> Quote:
> Originally Posted by *nick_danger* /forum/post/22087909
> 
> 
> 
> What's the best way to deal with the reflective nature of the slab? 2x4 framed subfloor filled with insulation with pad/carpet over? Just a pad/carpet over the slab itself? What about the corners (floor/wall edges)?
> 
> 
> Thanks.



Check my build thread post #25 shows my floor treatment.

http://www.avsforum.com/avs-vb/showt...2#post15187322


----------



## Digital_Chris

Here is a question regarding peaks and nulls caused by LFE waves smashing together (forgive me, I forgot the technical term for this)... Is the rear wall usually the biggest suspect to this problem? I know that bass is mostly omni-directional but I feel that the rear wall would be the highest priority to treat for bass, other than the corners.


I'm considering making a false wall roughly 2' from the back of the theater and filling that new cavity (complete width and height of the rear wall) with fluffy insulation to help with a 30hz peak at my rear seats (and possibly other smaller peaks and dips throughout the seating area). If I do this, the front of the false wall will certainly contain material for mid/high frequency reflection, 1/8" plywood of similar I take it, or just 6 mil plastic maybe? Possibly vertical strips of the mentioned material?


Or, should I skip all of that and build a couple of tuned helmholtz resonators? Maybe some mambrane panel absorbers on the back wall? Hmm..


Also, can a room be "too small" for tuned absorbers to work properly (helmholtz or membrane)? I think I saw Ethan mention that for smaller rooms, other options are recommended. Speaking of Helpmoltz resonators, does it matter where in the room they are placed?


What are your thoughts on those ideas?


----------



## CaliCool

Question guys...


My corners have all obstructions if I plan to put a floor to ceiling bass trap. Hard situation, I know!


The corners on the front, after advancing .200m due to the projector cove, will either hit the window or will interfere with the Blu Ray/PS3 Storage that is within the cove.


Are there other options aside from putting it on the corners floor to ceiling?


----------



## Dennis Erskine

Chris


Generally, it is the first three, or four, axial room modes which are most troublesome. Axial modes are length, width and height. If you treat only the back wall, you can only affect length modes. You cannot address a width mode with treatments on a back or front wall regardless of the type of treatment used (resonators or otherwise).


From a practical perspective, resolving modal response issues in small rooms requires multiple methods and techniques ... not just some form of absorption ... to address.


----------



## nick_danger




> Quote:
> Originally Posted by *Irv Kelman* /forum/post/22089843
> 
> 
> Check my build thread post #25 shows my floor treatment.
> http://www.avsforum.com/avs-vb/showt...2#post15187322












I would say that your thread gave me more ideas than just floor treatment! Very nice work. Can I copy some of that?


----------



## wingnut4772

I doubled up on the curtains behind the couch after reading here that they need to be thick. They are in front of a set of French doors. Will these be effective at diffusion and reflection?


----------



## wingnut4772




> Quote:
> Originally Posted by *wingnut4772* /forum/post/0
> 
> 
> I doubled up on the curtains behind the couch after reading here that they need to be thick. They are in front of a set of French doors. Will these be effective at diffusion and reflection?



I left the thin ones on top ( to be pretty )and there are blackouts underneath.


----------



## myfipie




> Quote:
> Here is a question regarding peaks and nulls caused by LFE waves smashing together (forgive me, I forgot the technical term for this)... Is the rear wall usually the biggest suspect to this problem? I know that bass is mostly omni-directional but I feel that the rear wall would be the highest priority to treat for bass, other than the corners.



Denis gave you the right answer but just to add, generally speaking the back wall is your next place to solve low end problems. Some of it is SBIR (some call this LBIR) and so on. Keep in mind though that modes are not just length though.

As far as what kind of treatment, tuned trapping is GREAT and we install it into a lot of rooms, but if it is not built correct then you may end up wasting a lot of time and money. Basically unless you feel 100% confident in the design (and your skills/understanding) then I would just stick with broad band. FYI it takes a lot of tuned traps on the wall also, so don't think you can build a 2x2 unit and think all the problems are solved. Plan on 15 to 25% of the wall covered.


----------



## Irv Kelman




> Quote:
> Originally Posted by *nick_danger* /forum/post/22098741
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I would say that your thread gave me more ideas than just floor treatment! Very nice work. Can I copy some of that?



Sure










It is a Dennis Erskine designed theater and I love it.


Have him design one for you.


----------



## Digital_Chris




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/8910#post_22097342
> 
> 
> Chris
> 
> 
> 
> Generally, it is the first three, or four, axial room modes which are most troublesome. Axial modes are length, width and height. If you treat only the back wall, you can only affect length modes. You cannot address a width mode with treatments on a back or front wall regardless of the type of treatment used (resonators or otherwise).
> 
> 
> 
> From a practical perspective, resolving modal response issues in small rooms requires multiple methods and techniques ... not just some form of absorption ... to address.



What types of treatment do you recommend for low end absorption since I don't have mega room to work with? Also, I figured the back wall was the contributor to the big peak at 33hz, the bob golds calculator shows this... 31.4 hz 35'12", 17'12", 8'12" (1,0,0 Axial). It looks like a length problem to me with my room being 18' long? How would I treat the width and height modes for bass?


> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/8910#post_22098974
> 
> 
> 
> Denis gave you the right answer but just to add, generally speaking the back wall is your next place to solve low end problems. Some of it is SBIR (some call this LBIR) and so on. Keep in mind though that modes are not just length though.
> 
> 
> As far as what kind of treatment, tuned trapping is GREAT and we install it into a lot of rooms, but if it is not built correct then you may end up wasting a lot of time and money. Basically unless you feel 100% confident in the design (and your skills/understanding) then I would just stick with broad band. FYI it takes a lot of tuned traps on the wall also, so don't think you can build a 2x2 unit and think all the problems are solved. Plan on 15 to 25% of the wall covered.



I know modes are not only length, but I'm not sure how to treat for width and height modes, I don't know if their even a problem in my room


----------



## CaliCool

Hey guys! It's me again with additional queries.


The room has come a looong way... I've long resigned the fact that rockwool in between gypsum board will not help my room acoustics at all and has now shelled almost $700 for acoustic treatments.


If any of you remember my floor plan... you will be familiar with my case. But anyway here's what I did:


Two panels on each side (24x48x4 Rockwool inside)

One panel (24x48x4 Rockwool angled on top of the projector screen side)

Four bass traps (24x43x4 Rockwool) on all corners (4) angled 45 degrees to cover the corners.

Four wood diffusers on the ceiling.


I also will definitely buy a "hairy" carpet since I have engineered wood.


And again, all windows and sliding doors will have drapes over them. (Blackout Curtains)


Question: Since I haven't fired up the equipment yet... the room is on its finishing stage... Did I do great on improving the room acoustics? What else do I need to do?


Maybe next week (a BIG MAYBE) I'll be able to start setting up the equipment already. For now though, all I can do is wait and prepare the room for it.


----------



## myfipie




> Quote:
> I know modes are not only length, but I'm not sure how to treat for width and height modes, I don't know if their even a problem in my room confused.gif


Well the way to find out is to test the room.
http://www.gikacoustics.com/video_rew_room_eq_wizard_tutorial.html


----------



## Digital_Chris

Thanks Glenn, I should have been more specific. I have measured the room quite a bit but since there are so many room modes (length, width and height), by looking at my graphs, I'm not sure what ones are being problematic. Let me post a few plots later and see what you think


----------



## Digital_Chris

Here are a few graphs for you to take a gander at...

*This is my front center seat overlayed with my rear center seat. Blue is rear row...*










*Rear seat waterfall...*










*Front seat waterfall..*











What areas do you think might be room mode related?


----------



## BasementBob




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/8910#post_22113218
> 
> 
> What areas do you think might be room mode related?


60hz, 80+hz, 110+hz.

What are your room dimensions?

Do you see these peaks if you put the microphone in 4 other places? (sound only matters where the ears are, but questions are answered all over the room, such as within a few inches of a tri-corner)

Can you move your speakers so they don't excite these?


----------



## calimark

If he has a huge dip at 110+ on the first chart, why does the waterfall show such high DB ?

Grap shows lower than 45db and waterfall shows 75-80 db


----------



## Digital_Chris

Room dimensions are 18 x 10.5 x 7


Speakers are mounted into the wall, they cannot be moved.


Look a little closer at the graphs, the peak in the waterfall is about 125-130hz, the dip is right before that around 110hz. It's a little deceiving while reading the waterfall as the ringing drops of at an "angle" compared to the actual dips/peaks.


----------



## calimark

Ok upon closer look you are correct, but even then its still a few off but I wont quibble .


I've seen your posts on other board as well..remind me again 2 subs? or 1?


I'm trying to follow as much here as I shall be doing the same soon- measuring and treating what I can.


----------



## BasementBob




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/8910#post_22113609
> 
> 
> Room dimensions are 18 x 10.5 x 7
> 
> Look a little closer at the graphs, the peak in the waterfall is about 125-130hz, the dip is right before that around 110hz.



60hz, is near a potential front back axial.

80hz, is near a potential up down axial.

107hz is near a potential left right axial.

125 hz is near a potential front back axial.


I'm wondering if RPG {Modex Corner, Modex Edge, Modex Module}x{63hz, 80hz, 100hz, 125hz} might be useful.

Or some much cheaper superchunks along all bi-corners (four wall-wall bi-corners, and four wall-ceiling bi-corners).


If you do the superchunks, experiment first. Lean 4" of unfinished 703 against the floor-walls, and against the wall-walls, and measure and listen to see what happens.


----------



## Digital_Chris

I've already done superchunks almost floor to ceiling in the rear two corners, a little help with the ringing I think but nothing significant, no room response change anyway.


----------



## BasementBob




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/8910#post_22114086
> 
> 
> I've already done superchunks almost floor to ceiling in the rear two corners, a little help with the ringing I think but nothing significant, no room response change anyway.



Those might help a little bit with the 60hz and 125hz, but probably nothing on the 80hz and 107hz. What happens if you take them out?


EDIT: Yea, it looks like that's what they did. A 60hz dip smoothed out a bit, and a 125hz peak dropped down a bit, and no change at 80/107hz.
http://www.avsforum.com/t/1401657/first-run-with-rew-advice-and-tips-please#post_21900503


----------



## Brucemck2

You could try adding an active device; these have been well reviewed:

http://www.spatialcomputer.com/page9/page10/page10.html


----------



## FOH




> Quote:
> Originally Posted by *Brucemck2*  /t/255432/acoustical-treatments-master-thread/8910#post_22114643
> 
> 
> You could try adding an active device; these have been well reviewed:
> http://www.spatialcomputer.com/page9/page10/page10.html



Any additional information/links wrt _well reviewed_? I like to read it.


There was a similar such product/approach back in the 80's. I thought Nelson Pass may have been involved, but I'm not sure. It consisted of a tall cylindrical tube product, with transducers top and bottom, placed logically at pressure zones in the room,....floor and ceiling. With two of these in the rear two corners of a room, I recall the reviewer raving about the subsequent acoustic results, and added bass detail and delineation. With a mic, amplification, and an attempt to null the the energy build-up it was well received wrt pro reviewers, but commercially, not so much IIRC.


----------



## Digital_Chris

Yeah, besides, it's a bit out of my price rance for what it does. Thanks for the link though.


----------



## Kach22

I came up with a plan to make *eight* 2' x 4' acoustic panels for $100. Please let me know if there are any issues I have overlooked or any other mistakes/misconceptions that will cause these to not work out.

*Materials:*
$43 for 8-Pack of 47"L x 23"W x 3"D Stone Wool Insulation Batts 
$32 for one 4' x 8' x 3/4" MDF 
~$25 for 6 yards of 60" Burlap

*Steps:*

Cut the MDF into 3" wide strips that are all 4' long, then cut one third of those in half. This will yield 20 3/4" x 3" x 4' strips and 20 3/4" x 3" x 2' strips to build the frames.
Overlap 3" of MDF in each corner, with the strips laying flat, and use wood glue plus two screws in each corner.
Lay a batt of stone wool on the frame.
Cover the batt with a slightly oversized piece of burlap.
Flip the frame, batt, and burlap over.
Pull burlap tight and staple to the back of the frame.


I plan on using picture hanging hardware and picture wire to hang these. With 3" of frame all around to work with, these could be hung or more permantely attached using just about any method you want.


----------



## myfipie

That all sounds fine BUT you really want to make the panels 4" if at all possible.


----------



## willscam

....and burlap is highly flammable.


----------



## Kach22




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/8940#post_22124300
> 
> 
> That all sounds fine BUT you really want to make the panels 4" if at all possible.



I'm trying to do this for a maxium cost-to-benfit ratio. I have wood panel walls in the den where my setup is and want to improve it as much as possible without putting too much money into something temporary; I will be moving in 1-2 years. I saw a 6-pack of 2' x 4' batts that are 3.5" thick (I would need more than one pack), but after that everything jumps up to 6.5" or thicker (I think those would stand out a bit too much for the fiancee), ordering offline has high shipping costs so I'd rather buy it locally.


I put that plan up as a general guide to what I was planning. I will actually be building 5 panels as I described and then making one double thickness panel to use as a bass trap in one corner. I may make another panel or two (smaller) with the remaining material if I find I missed any bad spots.


> Quote:
> Originally Posted by *willscam*  /t/255432/acoustical-treatments-master-thread/8940#post_22124973
> 
> 
> ....and burlap is highly flammable.



Is there another inexpensive material that would be a better choice? I'm using these as separate hanging panels, not fully lining walls with them, so it shouldn't be too dangerous. The insulation is fire-resistant, so that should help too.


----------



## willscam

You could hit the burlap with a fire retardant spray .


If no one smokes and you don't have any open flame in the room you should be alright without any treatment. Alot of people don't realize how flammable burlap is. I just thought I'd give you a heads up.


----------



## nickbuol

There have been arguments here that as soon as you start spraying a product onto a fabric, that it impacts the ability of said fabric to be as acoustically transparent as it originally was. Not sure how much spray it would take to make a noticeable difference, but I wanted to mention it as I am sure that some people saturate their fabric more than others... I have ZERO personal experience with this, just bringing up some points that I heard myself when I was looking at fabric choices.


----------



## Kach22




> Quote:
> Originally Posted by *willscam*  /t/255432/acoustical-treatments-master-thread/8940#post_22125621
> 
> 
> You could hit the burlap with a fire retardant spray .
> 
> If no one smokes and you don't have any open flame in the room you should be alright without any treatment. Alot of people don't realize how flammable burlap is. I just thought I'd give you a heads up.



No smokers, but we do burn a candle occassionally. I'll be extra cautious of the burlap when open flames are present. Thanks for the heads up.


----------



## nickbuol

There is an insurance concern too. Elsewhere, in this thread I believe, there is talk of the increasing potential for a denied insurance claim should they determine that non-flame retardant material was used for things like panels or false walls.


I know that you say that you will be "extra cautious" but we are talking about accidents here. I don't think that many house fires are started intentionally, but they were because of a tiny lapse in judgement, small oversight, or just freak combination of variables that the homeowner "never thought would happen".



Please take this just as someone else being concerned that you don't burn your house down by using materials that catch fire easily, and not someone being a prick about it.


----------



## Kach22




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/8940#post_22127724
> 
> 
> There is an insurance concern too. Elsewhere, in this thread I believe, there is talk of the increasing potential for a denied insurance claim should they determine that non-flame retardant material was used for things like panels or false walls.
> 
> I know that you say that you will be "extra cautious" but we are talking about accidents here. I don't think that many house fires are started intentionally, but they were because of a tiny lapse in judgement, small oversight, or just freak combination of variables that the homeowner "never thought would happen".
> 
> Please take this just as someone else being concerned that you don't burn your house down by using materials that catch fire easily, and not someone being a prick about it.



That's all very true. I will use a fabric that is flame retardant, even if it's just treated burlap; spending a few extra bucks now is better than a burned down house later. I plan on building these panels around the end of this month, I wanted to give myself a good amount of time to learn and read more posts since I'm clueless about acoustic panels. Thanks for the advice.


----------



## kromkamp




> Quote:
> Originally Posted by *Brucemck2*  /t/255432/acoustical-treatments-master-thread/8910#post_22114643
> 
> 
> You could try adding an active device; these have been well reviewed:
> http://www.spatialcomputer.com/page9/page10/page10.html



I would also be interested in any reviews of this device. I had been mildly contemplating another similar device (the Bag End e-trap), seems like this one is better and cheaper.


The biggest problem is still price though - for the same amount of money you can get a decent amount of subwoofer, and the more subwoofers you throw at the room the more the problem goes away.


----------



## FOH




> Quote:
> Originally Posted by *dragonfyr*  /t/255432/acoustical-treatments-master-thread/8940#post_22129173
> 
> 
> I would suggest treating the mid third of each side wall with BAD panels backed by a minimum 4" porous backing. This provides a broadband treatment that is absorptive in the lower registers of the specular region while providing sufficient moderate diffusion across the broadband specular range of interest.
> 
> 
> And since common real world speakers do not exhibit uniform spatially distributed power responses, I would also measure the each source at the listening position(s) and identify any remaining high gain sparse early reflections and surgically provide just enough additional absorptive treatment to damp only them, as they will effect imaging, localization, intelligibility and coloration.



Good advice there



I'm not sure if dragon concurs, however I'd suggest little good comes from the ceiling between the mains and the LP, IMO one can do much worse than aggressively absorbing this energy,..not the exact approach I've taken but perhaps the "cloud" style could be adopted.


Thanks dragon, good contribution.


----------



## FOH

That's the panel(s) I've been contemplating,...the curved BAD panel that Nyal offers at his Acoustic Frontiers site . Expensive or I'd already had the panels I'm interested in.


Good stuff


----------



## FOH




> Quote:
> Originally Posted by *dragonfyr*  /t/255432/acoustical-treatments-master-thread/8940#post_22129893
> 
> _Make_ the BAD panels!



I've seen some nice DIY efforts on such panels. At one time I considered it, we'll see. I'm battling some serious medical issues that limit many things I get myself into, (but I did crawl through my attic and construct an IB,...took me several months)


I may hit you up for links/details etc, I do remember a big DIY effort of huge BAD panels,...



Thanks for the offer dragon


----------



## NJ Jackals

Free sheets of OC703 in 08822 (NJ) if somebody wants it. I have 15+ sheets of the 2'x4', 1" thick. Otherwise, it goes in the dumpster. Let me know if anyone is interested.


----------



## Brad Horstkotte

Are BAD panels fussy about side-by-side placement of panels with the same hole pattern, the same way that QRD panels are? Or due to the density of the "wells", not an issue?


----------



## myfipie




> Quote:
> Originally Posted by *dragonfyr*  /t/255432/acoustical-treatments-master-thread/8940#post_22129173
> 
> 
> I hate to be the naysayer, but even 4" thick panels are not going to be notably effective below 100 Hz, and certainly not if they are not spaced at least 4" from the wall!
> 
> For what its worth, a 4" panel mounted to the wall has essentially the same performance as a 2" thick porous panel spaced 2" from the boundary. So if the treatment is appropriate for the problem, take advantage of the closest thing we get to a free lunch in acoustics and save the money on materials and make up for it with a bit of applied intelligent creativity.
> 
> ...But they do make excellent broadband specular absorbers for the low/midrange frequencies and up.
> 
> And thinner than 4" will do NOTHING for the low frequencies.
> 
> You have already crippled yourself in stating that you need inexpensive solutions. Porous absorption is the cheapest, and its limitation is that it takes THICK porous traps placed far away from the low velocity boundaries in order to be maximally effective at 1/4 wavelength boundary spacing distances.
> 
> If you want 'thinner' treatments you require pressure based devices, the most effective of which are VPR style panels (of which RPG's Modex is an example). These should be stacked floor to ceiling in the corners which are regions of maximal PRESSURE (NOT velocity, and hence why classically placed wall mounted porous absorption is NOT maximally effective there!). Additionally, they can be mounted with great benefit at any wall-ceiling intersection as well. Corners are ideal - especially trihedral corners - for pressure based devices as the pressure is maximum there.
> 
> Unfortunately, while they can be fabricated if one is familiar with the Fraunhaufer designs and mechanics, they are not trivial nor cheap.
> 
> As I said, I don't like being the curmudgeon, but I hate it more when someone spends lots of time, effort and money only to achieve a grand experiment demonstrating the limitations of a concept rather than achieving optimal - or even acceptable - desired results.
> 
> Also, while not bass trapping, to extend the model a bit to accommodate an integrated approach...as far as general broadband difussion in a HT, I would suggest treating the mid third of each side wall with BAD panels backed by a minimum 4" porous backing. This provides a broadband treatment that is absorptive in the lower registers of the specular region while providing sufficient moderate diffusion across the broadband specular range of interest.
> 
> And since common real world speakers do not exhibit uniform spatially distributed power responses, I would also measure the each source at the listening position(s) and identify any remaining high gain sparse early reflections and surgically provide just enough additional absorptive treatment to damp only them, as they will effect imaging, localization, intelligibility and coloration.
> 
> BTW, the BagEnd active trap works well for issues in its range of from 20Hz to 65Hz - albeit in a location specific manner (meaning it will not address multiple problems in multiple locations) and that it is quite pricey.



I agree but also keep in mind that when a broad band panel (4" or more) is straddling the corner it will reach way below 100hz quite well. This has been proven many times in many rooms and in many labs.


----------



## Brad Horstkotte

Perfect, thanks dragon


----------



## mtbdudex

For others:

Member Eric2000 (a fellow IB cult member also) did a great job making removable corner triangle bass traps with pink fluffy, look here:
http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/120#post_22131618 

More picts in the link above.


> Quote:
> My traps are 24x24x34 inch triangles, are about 3.5 feet tall, and probably weigh less than 10lbs each. Since I need access to one of the corners for a doorway, I made them stackable and moveable. I started by cutting triangles, drilling holes for the threaded rod, and inserting T-Nuts for the sides that stack on one another:


----------



## myfipie




> Quote:
> If they, as has been stated quite a few times, need a treatment with more modest space requirements, porous absorption is NOT the way to go with bass traps. Especially if they require serious attention to modal issues below 100 Hz
> 
> 
> In that region tuned resonant traps address specific problem frequencies much more effectively with a minimum loss of space. The trade off is that what they gain in space is 'lost' in cost and complexity of design.



Sure something like our Scopus Tuned Traps














works great below 100hz but not everyone has the funds nor the right kind of room for it. Broad band will work when in corners and also deals with the full frequency range which can be very helpful in smaller rooms.. Like I said it has been proven may times and in many rooms.












Edit: I do want to point out that if you are trying to deal with say 40hz broad band is not the way to go. Sure if you put enough of them in corners it will help A LOT but it will not solve it. But keep in mind that even something tuned will have to be pretty darn thick (around 10") and is going to take quite a bit of coverage on the wall to work. It is not like you can install 8 squ feet of something tuned and think the problem will be solved.


----------



## myfipie




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/8940#post_22132736
> 
> 
> For others:
> 
> Member Eric2000 (a fellow IB cult member also) did a great job making removable corner triangle bass traps with pink fluffy, look here:
> http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/120#post_22131618
> 
> More picts in the link above.
> 
> 
> 
> Quote:
> My traps are 24x24x34 inch triangles, are about 3.5 feet tall, and probably weigh less than 10lbs each. Since I need access to one of the corners for a doorway, I made them stackable and moveable. I started by cutting triangles, drilling holes for the threaded rod, and inserting T-Nuts for the sides that stack on one another:
Click to expand...


Nice!!


----------



## pepar




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/8940#post_22132773
> 
> 
> Nice!!


He's got "prior art" Glenn.


----------



## Eric2000




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/8940#post_22132899
> 
> 
> He's got "prior art" Glenn.



Uh-oh. I didn't mean to cause any trouble







I just wanted to share my work. Thanks for the plug, Mike!










Eric


----------



## longfellowfan




> Quote:
> Originally Posted by *Kach22*  /t/255432/acoustical-treatments-master-thread/8940#post_22124131
> 
> 
> I came up with a plan to make *eight* 2' x 4' acoustic panels for $100. Please let me know if there are any issues I have overlooked or any other mistakes/misconceptions that will cause these to not work out.
> *Materials:*
> $43 for 8-Pack of 47"L x 23"W x 3"D Stone Wool Insulation Batts
> $32 for one 4' x 8' x 3/4" MDF
> ~$25 for 6 yards of 60" Burlap
> *Steps:*
> 
> Cut the MDF into 3" wide strips that are all 4' long, then cut one third of those in half. This will yield 20 3/4" x 3" x 4' strips and 20 3/4" x 3" x 2' strips to build the frames.
> Overlap 3" of MDF in each corner, with the strips laying flat, and use wood glue plus two screws in each corner.
> Lay a batt of stone wool on the frame.
> Cover the batt with a slightly oversized piece of burlap.
> Flip the frame, batt, and burlap over.
> Pull burlap tight and staple to the back of the frame.
> 
> I plan on using picture hanging hardware and picture wire to hang these. With 3" of frame all around to work with, these could be hung or more permantely attached using just about any method you want.



You might want to look at Guilford of Maine Fabric. That is what is used on my DIY acoustic panels because of its flame retardant properties.


----------



## myfipie




> Quote:
> And mentioning a specific very effective solution: the VPR based RPG Modex tuned resonators are ~4" thick, and you have a choice of specifically tuned modules effective in the 30-100 Hz range or of tuned modules that feature an additional perforated membrane based 'broadband extension" extending the effectiveness from 40 Hz to 5kHz.



Sure for ours tuned to 70hz it is also 4" but not the 40hz ones. I believe it is the same for them. Could be wrong as there website is under construction right now. Needless to say I remember seeing the Modex around 10" when tuned that low, which makes total sense.


----------



## localhost127




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/8940#post_22129972
> 
> 
> I may hit you up for links/details etc, I do remember a big DIY effort of huge BAD panels,...



another diy:

http://www.component.se/forum/index.php?s=e3a53ca15a1b0cbda913ad1d44eceea2&showtopic=6176&st=105&p=145270entry145270 

http://www.component.se/forum/index.php?s=729c02933afe06ba9e65880d9b12f1b2&showtopic=6176&st=150&p=150191entry150191


----------



## FOH

Thanks Local,.. that's the exact build that always comes to mind when someone references this topic.


----------



## rabident

How important is room symmetry to acoustics?


My side wall has a 7" bump out for about 25' of it.


________________

|============|

|============|

|============|

|============|

|===========|*

|===========|*



Is it better to loose the 7" and run the wall straight, or might that 7" of space be useful for treatments? Room is 21' 3" wide in the narrow part, so I don't really need the extra 7".


----------



## sukumar

Do we need to place any absorption panels from floor to just ear height only? Is there any reason?


Also, I am using Fidelio velvet from JB Martin cloth for ceiling and walls. Though, Fidelio is expensive, it is recommended in the forum as best material for darkness. However, I was told it is not good to cover bass traps or speakers since it may block sound to go inside. If it is not good for bass traps, what do you recommend to cover oven corning OC 703 super chunk bass traps? I would like suggestions to buy from Joann or Hancock or online. Thanks for your help.


----------



## Digital_Chris




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/8940#post_22213898
> 
> 
> Also, I am using Fidelio velvet from JB Martin cloth for ceiling and walls. Though, Fidelio is expensive, it is recommended in the forum as best material for darkness. However, I was told it is not good to cover bass traps or speakers since it may block sound to go inside. If it is not good for bass traps, what do you recommend to cover oven corning OC 703 super chunk bass traps? I would like suggestions to buy from Joann or Hancock or online. Thanks for your help.



The usual is Guilford of Maine FR701 fabric, many colors available! You can also grab some speaker grill cloth from JoAnn fabrics, not too expensive either


----------



## Brad Horstkotte

Rosebrand.com also carries speaker cloth that is available in wide widths, and is also fire retardant (which FR701 is, but most fabrics from Joanne's aren't).


----------



## Digital_Chris

Oooh, very good addition Brad


----------



## sukumar




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/8940#post_22214435
> 
> 
> The usual is Guilford of Maine FR701 fabric, many colors available! You can also grab some speaker grill cloth from JoAnn fabrics, not too expensive either



Thanks for quick reply. Appreciate if you can share the type of velvet.I find they have stretch velvet, cotton velvet and premier velvet. Did anybody compare or test these cloth recently? I guess you can get either very dark without light refleciton or acoustic transparent, but not both.


----------



## sukumar




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/8970#post_22214448
> 
> 
> Rosebrand.com also carries speaker cloth that is available in wide widths, and is also fire retardant (which FR701 is, but most fabrics from Joanne's aren't).



Thanks. Are you referring to this?
http://www.rosebrand.com/product800/102-Black-Speaker-Cloth-FR.aspx?tid=2&info=speaker%2bcloth 


If it is and you used, how dark to prevent light reflections.


----------



## Digital_Chris




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/8970#post_22214728
> 
> 
> Thanks for quick reply. Appreciate if you can share the type of velvet.I find they have stretch velvet, cotton velvet and premier velvet. Did anybody compare or test these cloth recently? I guess you can get either very dark without light refleciton or acoustic transparent, but not both.



No problem.


I bought some of their velvet for my screen border and it wasn't their top of the line stuff, I think it was the middle ground, it did de-thread fairly easily if you weren't careful. The black FR701 is pretty dark, any of the black AT material should be dark enough for wall panels and bass traps, heck, even around your screen for your false wall! I don't think it will be THAT much of an issue unless your trying to make the whole room literally disappear. Poke around in some other threads with room treatments and you will get some ideas on what type of fabric was used for the panels and how they like it


----------



## BIGmouthinDC

GOM FR701 pass through test (granted light isn't the same as sound but it is what it is)











Hancock Micro velvet (100% polyester) unfortunately they no longer stock it.











I used it for my screen wall, the only thing firing through it is the Sub woofer below screen, works fine.











The black on the ceiling is the FR701.


There is a significant difference in the blacks of the two fabrics, Velvet reflects less light but as you can see in the picture in real lighting conditions you can't tell the difference


----------



## Greg121986

Looking for experienced DIY'ers to lend me some advice here. I am considering spoonflower fabrics for acoustic treatments in my bedroom for right now. I have a small 2 channel system and I also play guitar in there. The room is 11x11' and is all bare walls right now, except one wall where my guitars hang. I am planning to make only 1 acoustic panel right now because I want to have something custom painted onto the spoonflower fabric. I am thinking 42" wide by some appropriate height that will be determined by the size of the painting.


I am speaking with an artist who has done some painting on canvas that I really enjoy. I am hoping he can paint onto the spoonflower fabric as well. However, I am concerned that the paint may end up filling in all of the gaps of the fabric and this would no longer be an acoustic panel at that point. Has anyone tried to paint onto the spoonflower fabric? Maybe this would work with water colors?


----------



## sukumar

I read in the forum that pink material has GFR of 5000 vs OC 703 of 17000 and it is recommended to use pink material if space is not problem. My room is decent 21 feet long and 13 feet 6inch wide for 1/3 of room and 16 feet for rest of the room. I only have one row of seating all the way back.


However, at the front I have 10 feet long screen and there is only 1 and 1/2 feet left on each side. I am assuming that this is not enough space for pink material. Let me know if I am wrong.


----------



## MuaySteve

Hey guys. I am getting ready to do some acoustic panels for the first time. I'm in Canada and having a hard time finding the recommended materials such as Owens Corning 703.


I have found this from Roxul, and it is readily available at Home Depot: Roxul R6 ComfortBoard IS
http://www.homedepot.ca/product/roxul-r6-comfortboard-is-insulated-sheathing-board-for-basement-and-exterio/995375# 


Anyone know if this would be suitable? I'd prefer to use Roxul over a fiberglass (just a personal preference).


Thanks


----------



## Brad Horstkotte

Here's a document with the acoustic absorption properties - it should work fine:

http://www.roxul.com/files/RX-NA-EN/pdf/Residential%20Sell%20Sheets/ComfortBoard%20IS.pdf


----------



## robc1976

Need a bit of advice here, I have decided the subs sound best up front (both of them)....tried front/back left/right at ever possible location and this gave the best response....but does have some type of reverb or echoing/boomy bass (slight bit). My question is this...I have 3 8" thick monster bass traps on the back wall and was wondering if it would help the bass a bit to put a monster bass trap above each sub in the front or even put a monster trap above the TV for now instead of the back since it seems they would be more effective up front? I am getting more 242's for the front also (would get more monster traps for the back-wall if I need to use them up front) and 6 more diffusors for the back. I can tell you this, I had left a ceiling panel out above the TV and hadnt realized it and got a bad echo....put the tile in and it was much better! I know the best option is to insulate the ceiling LOL!! I can stand in front of the TV and heare a echo/reverb so maybe a bass trap there as well.


I would like to keep the subs up front so maybe try them on the outside of the fronts or maybe at the 25% mark of the room. I can not do a 50% side wall placement, I tried 50% and one sub at 60% and it was absolutely terrible. I did the sub crawl and best placement is where they are now, 2nd best is at the sidewalls next to the wides. They have a good response but I hear a low like hum in movies with the back round bass so that is why I am considering bass traps on the front sound stage. Room has tri-traps from top to bottom on all corners of the room.

*Here are pics:*


----------



## MuaySteve




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/8970#post_22236443
> 
> 
> Here's a document with the acoustic absorption properties - it should work fine:
> http://www.roxul.com/files/RX-NA-EN/pdf/Residential%20Sell%20Sheets/ComfortBoard%20IS.pdf



Thanks for the reply. I hadn't seen this specific product discussed anywhere.


----------



## Vincehoffman




> Quote:
> Originally Posted by *MuaySteve*  /t/255432/acoustical-treatments-master-thread/8970#post_22235387
> 
> 
> Hey guys. I am getting ready to do some acoustic panels for the first time. I'm in Canada and having a hard time finding the recommended materials such as Owens Corning 703.
> 
> I have found this from Roxul, and it is readily available at Home Depot: Roxul R6 ComfortBoard IS
> http://www.homedepot.ca/product/roxul-r6-comfortboard-is-insulated-sheathing-board-for-basement-and-exterio/995375#
> 
> Anyone know if this would be suitable? I'd prefer to use Roxul over a fiberglass (just a personal preference).
> 
> Thanks



Hey Steve,


Look up your local Multi-Glass outlet. Mine is in Stoney Creek but there should be at least one in the GTA. They sell an OC703 equivalent from Manson that goes for $78 per bag of 10 4'x8'x2" boards.


Happy Trails!

MTB Vince


----------



## Al Sherwood




> Quote:
> Originally Posted by *Vincehoffman*  /t/255432/acoustical-treatments-master-thread/8970#post_22241551
> 
> 
> Hey Steve,
> 
> Look up your local Multi-Glass outlet. Mine is in Stoney Creek but there should be at least one in the GTA. They sell an OC703 equivalent from Manson that goes for $78 per bag of 10 4'x8'x2" boards.
> 
> Happy Trails!
> 
> MTB Vince



Do you have the actual product name by MANSON, they have a number of them, looking for a supplier on the west coast...


Thanks!


----------



## robc1976




> Quote:
> Originally Posted by *robc1976*  /t/255432/acoustical-treatments-master-thread/8970#post_22236718
> 
> 
> Need a bit of advice here, I have decided the subs sound best up front (both of them)....tried front/back left/right at ever possible location and this gave the best response....but does have some type of reverb or echoing/boomy bass (slight bit). My question is this...I have 3 8" thick monster bass traps on the back wall and was wondering if it would help the bass a bit to put a monster bass trap above each sub in the front or even put a monster trap above the TV for now instead of the back since it seems they would be more effective up front? I am getting more 242's for the front also (would get more monster traps for the back-wall if I need to use them up front) and 6 more diffusors for the back. I can tell you this, I had left a ceiling panel out above the TV and hadnt realized it and got a bad echo....put the tile in and it was much better! I know the best option is to insulate the ceiling LOL!! I can stand in front of the TV and heare a echo/reverb so maybe a bass trap there as well.
> 
> I would like to keep the subs up front so maybe try them on the outside of the fronts or maybe at the 25% mark of the room. I can not do a 50% side wall placement, I tried 50% and one sub at 60% and it was absolutely terrible. I did the sub crawl and best placement is where they are now, 2nd best is at the sidewalls next to the wides. They have a good response but I hear a low like hum in movies with the back round bass so that is why I am considering bass traps on the front sound stage. Room has tri-traps from top to bottom on all corners of the room.
> *Here are pics:*


went with the placement above but moved the subs out a bit and left the treatments as they are...still didn't get a sub distance reading lol!!


----------



## sukumar

Can anybody share how you built bass traps that are from left to right of the room either front of back? Basically, these are embedded between corner super chunks. I have following questions.


1. Can these center bass traps need to be in triangle? or can I stack one or other?

2. How many are recommended to stack one over other?


On other question.


Is less than 1 mil plastic considered acoustically transparent?


----------



## pepar

 http://peparsplace.com/pg25.html


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/8970#post_22246825
> 
> http://peparsplace.com/pg25.html



Thanks for sharing the link. Pepar, I am not able to see what is on the floor from corner to corner bass traps. Do you have 24 inch facing triangle bass traps on the floor? Also are these broad band or just bass traps? I will go through the web site again to understand better.


----------



## pepar

the 24" x 48" sheets were cut into 8 triangles with 24" faces and that is what is used in the vertical and horizontal traps. since they are not faced with anything, i'd say that they are definitely broadband. in fact, any fiberglass bass trap like this (unfaced) will be broadband.


the traps are in the wall/wall corners floor to ceiling and wall/ceiling corner left wall to right wall. none on the floor/wall corner.


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/8970#post_22248634
> 
> 
> the 24" x 48" sheets were cut into 8 triangles with 24" faces and that is what is used in the vertical and horizontal traps. since they are not faced with anything, i'd say that they are definitely broadband. in fact, any fiberglass bass trap like this (unfaced) will be broadband.
> 
> the traps are in the wall/wall corners floor to ceiling and wall/ceiling corner left wall to right wall. none on the floor/wall corner.



Pepar,


Thanks for quick reply. I read that first preference out of 12 corners is wall-wall corner from floor to ceiling. I understood. Is the second preference is on ceiling from left to right than on the floor? Appreciate if there is any information on the web site.


I thought on the floor from left side wall to right side wall bass traps will help SBIR.


----------



## pepar

I am not an acoustician, but as I understand it all two-surface corners are equal, though "tricorners" (wall/wall/ceiling and wall/wall/floor) are the best. Due to the way modes occur in a room, I *think* if you only trap wall/wall corners, and no wall/ceiling or wall/floor corners, there are modes that will not "meet" your traps.


Jeff


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/8970#post_22248772
> 
> 
> I am not an acoustician, but as I understand it all two-surface corners are equal, though "tricorners" (wall/wall/ceiling and wall/wall/floor) are the best. Due to the way modes occur in a room, I *think* if you only trap wall/wall corners, and no wall/ceiling or wall/floor corners, there are modes that will not "meet" your traps.
> 
> Jeff


Thanks for reply. I am surprised I can't find any information on order of preference for 12 corners that need acoustic treatment.


----------



## pepar

There is no order of preference. Aesthetics and practicality will most likely be determining factors as to which you use. Unless behind a false wall, most people don't do wall/floor corners. Though you might be able to do wall/wall/floor tricorners.


Jeff


----------



## giomania




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/5340#post_17396871
> 
> 
> Here are pictures of my screen wall with the screen installed. I will cover it with GoM and it will be flanked by curtains on both sides.
> 
> 
> 
> I installed an extra 8" deep section of triangles in the upper-right corner of the front wall. The remain un-treated area there in the picture has the electrical panel and the structured wiring (low-voltage) box. I was wondering if I should cut a piece of 2" JM 814 to fit in there. It would have to be moveable for occasional access.
> 
> 
> 
> If you recall from my previous pictures, I did not have the lower 16" of the front wall treated. My solution is to lean the 2" panels in the bottom corner like you see in the picture behind the screen wall. That should be OK, right?
> 
> 
> 
> Thanks for any input.
> 
> 
> 
> Mark



Sukumar,


Here are some pictures of my setup; hopefully they help you to understand.


Mark


----------



## sukumar




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/8970#post_22250512
> 
> 
> Sukumar,
> 
> Here are some pictures of my setup; hopefully they help you to understand.
> 
> Mark


giomania , Thanks for sharing. There is noway you get SBIR effect etc;-). I guess it is lot of work. I am curious to see if you have any graphs like frequency response or water fall.


----------



## sukumar

I am limited by size on back side of wall in one of the corner since there is door. I was told to use same size of super chunk bass traps to match on both corners of rear wall (The rule applies to front side as well, but I don't have size problem). Does anybody know what could happen if one is bigger than other?


----------



## giomania




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/8970#post_22251413
> 
> 
> giomania , Thanks for sharing. There is noway you get SBIR effect etc;-). I guess it is lot of work. I am curious to see if you have any graphs like frequency response or water fall.



Unfortunately, I do not.


Mark


----------



## rnrgagne

Hi guys, I'd appreciate some thoughts or advice. I'm looking to build some diy bass traps, with the WAF being the prime concern. I've got my HT in a new room which is multi-purpose so I have to put up with less than desirable result in favor of aesthetics.


First, I am wondering what's the smallest a circular corner bass trap can be to have reasonable effect?


Second, I'm thinking of building something like a quick & dirty trap inside a wicker basket as a frame. Basically I'm wondering if that's acoustically transparent enough to work in the bass frequencies assuming the weave isn't too tight?


Oh, and if this is a great idea, consider this post as patent pending lol!


----------



## Roger Dressler




> Quote:
> Originally Posted by *rnrgagne*  /t/255432/acoustical-treatments-master-thread/8970#post_22258156
> 
> 
> Hi guys, I'd appreciate some thoughts or advice. I'm looking to build some diy bass traps, with the WAF being the prime concern. I've got my HT in a new room which is multi-purpose so I have to put up with less than desirable result in favor of aesthetics.
> 
> First, I am wondering what's the smallest a circular corner bass trap can be to have reasonable effect?
> 
> Second, I'm thinking of building something like a quick & dirty trap inside a wicker basket as a frame. Basically I'm wondering if that's acoustically transparent enough to work in the bass frequencies assuming the weave isn't too tight?
> 
> Oh, and if this is a great idea, consider this post as patent pending lol!


Two subs the size of the wicker basket (placed optimally) will do a lot more than two bass traps (or 4 or 6 or 8) of the same size. Are you planning multiple subs? If so, might be best to see how they work out before going further with traps. No point solving a problem unless you have it.


----------



## rnrgagne

At this point I'm not thinking mulitple subs, my mains are more than adequate for music and are crossed at 40hz. I have a little Seismic 12 which is surprisingly visceral on LFE, and adequate enough for what's below my crossover points. Crossing over my mains that low is kind of like using multiple subs already, and I use Audyssey XT32 Pro, so there's a lot of help in that department. It does a great job in a less than stellar room.

My room's main issue is there's an 8' opening on the left side of the MLP into a foyer that houses a curved wall/staircase which acts like a parabolic mike and I'd like to put something in there.

Plus the room is actually pretty baren, it needs some "accessorizing" including HF treatments, as it can get out of hand at higher volumes. So long and short, I have some more homework to do, but I have this wicker idea from a decorative perspective I'd like to explore.


----------



## Roger Dressler




> Quote:
> Originally Posted by *rnrgagne*  /t/255432/acoustical-treatments-master-thread/8970#post_22260267
> 
> 
> At this point I'm not thinking mulitple subs, my mains are more than adequate for music and are crossed at 40hz. I have a little Seismic 12 which is surprisingly visceral on LFE, and adequate enough for what's below my crossover points. Crossing over my mains that low is kind of like using multiple subs already, and I use Audyssey XT32 Pro, so there's a lot of help in that department. It does a great job in a less than stellar room.


Understood. My point about multiple subs was not for increasing bass levels, but as an alternative to using passive bass traps, presumably to reduce bass lumpiness caused by room modes. If the system is not plagued by such uneven response, then no need.


> Quote:
> My room's main issue is there's an 8' opening on the left side of the MLP into a foyer that houses a curved wall/staircase which acts like a parabolic mike and I'd like to put something in there.


If there's some significant energy returning from that portal, then yes, killing it would be useful. Best to determine the spectrum of that before deciding on the solution.


> Quote:
> Plus the room is actually pretty baren, it needs some "accessorizing" including HF treatments, as it can get out of hand at higher volumes.


Yes, the pix show standard walls. Undoubtedly sound would benefit from some appropriate diffusion and absorption. I realize you are trying to minimize visual impact, but a large percentage of the surface will need coverage, more than the wicker baskets will address. I have found the standard GOM covered panels, in the right colors to blend with the walls (or ceiling), are not visually overbearing at all, and can be very effective in taming a live room.


----------



## rnrgagne

Thanks Roger, I appreciate your thoughts. They're actually not too far off from my own, but I doubt I'll be able to do anything but subtle treatments, maybe the artwork covered panels at best.

I don't plan on just plunking wicker baskets around the room willy-nilly, I'm actually thinking of using them as material to build architectural columns, perhaps with lighting incorporated into them, or as plant holders etc... I'm just in the infancy of thinking this through and just have loose concepts right now.

So I still would like to know how small a circular corner bass trap can be to have a degree of effectiveness.


----------



## FOH




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9000#post_22260808
> 
> 
> Understood. My point about multiple subs was not for increasing bass levels, but as an alternative to using passive bass traps, presumably to reduce bass lumpiness caused by room modes. If the system is not plagued by such uneven response, then no need.



Roger, I know what you're saying, however I want to clarify for those that may think otherwise; just because one's freq response may be smooth, doesn't necessarily mean that bass traps aren't warranted.


LF damping in general, and more specifically bass traps, can be effective in both the _frequency domain_, as you stated, *but also in the time domain*.


Both, examining waterfall graphs before and after bass traps, and listening to the subjective "tightness" in bass quality, typically reveals that bass traps add appreciably to the overall quality of the bass. So yes, the frequency response can be smoothed w/bass traps, but the decay characteristic of the room is also tightened up and is quite significant.




Thanks


----------



## sukumar

I have paradigm studio 100 speakers. To avoid speaker distraction while watching movie, it would help if they are as close to side wall as possible. I have 17x17x24 bass trap on the back of speaker. Here is the picture. Do you think any other absorption panel side of speaker helps SBIR?


----------



## pepar

Not what you are asking, but have you considered an acoustically transparent screen with the speaker behind it?


Jeff


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000#post_22263714
> 
> 
> Not what you are asking, but have you considered an acoustically transparent screen with the speaker behind it?
> 
> Jeff


Unfortunately, I am using Dalite high gain screen to handle brighness needed for 3d and it is not AT. I am not considering yet to replace screen.


----------



## rnrgagne




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9000#post_22263070
> 
> 
> Roger, I know what you're saying, however I want to clarify for those that may think otherwise; just because one's freq response may be smooth, doesn't necessarily mean that bass traps aren't warranted.
> 
> LF damping in general, and more specifically bass traps, can be effective in both the _frequency domain_, as you stated, *but also in the time domain*.
> 
> Both, examining waterfall graphs before and after bass traps, and listening to the subjective "tightness" in bass quality, typically reveals that bass traps add appreciably to the overall quality of the bass. So yes, the frequency response can be smoothed w/bass traps, but the decay characteristic of the room is also tightened up and is quite significant.
> 
> Thanks



That certainly was my experience in the previous well treated room I had. It had considerable bass trapping and that was despite the room's dimensions being built to have the fewest problems in the bass region. The combination led to probably the best bass I've yet experienced out of a system.


But in this new room I've got to be creative as I'm not starting from scratch. I need to know what the parameters are I'm working with for reasonably effective circular bass traps and if there's anything negative to using wicker as a frame.


----------



## pepar




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/9000#post_22263816
> 
> 
> Unfortunately, I am using Dalite high gain screen to handle brighness needed for 3d and it is not AT. I am not considering yet to replace screen.


So your question about the speakers being nearly touching the side wall is a good one that I will follow for an answer. If the proximity is not harmful, or can be mitigated with treatments and/or room correction, then you are OK.


Jeff


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000#post_22265252
> 
> 
> So your question about the speakers being nearly touching the side wall is a good one that I will follow for an answer. If the proximity is not harmful, or can be mitigated with treatments and/or room correction, then you are OK.
> 
> Jeff



I am trying to balance video experience vs audio. Based on feedback from the forum, I got highest possible size screen (142 inch). So, I was left with 1 and 1/2 feet on each side. (may wall is 13 feet 6 inch for around 8 feet and then changes to 16 feet).


I read that minimum distance is 20cm from either wall for speaker placement. I have bass trap (17x17x24) behind it. I can add 2 or 4 inch absorber (OC 703) on the side.


----------



## sukumar

My understanding is 2 inch oc 703 with 2 inch gap is equivalent to 4 inch OC 703 without airgap. Is it right? Is 2 inch OC 703 with 2 inch gap can handle reflections (I guess above 500hz)? I am going to make absorbers this week.


I already have corner 4 bass traps from floor to ceiling and front and back wall bass traps from side to side. I am trying to find if 4 inch really makes sense even for reflections.


----------



## pepar

Do you have a way to measure your room? REW and related gear or maybe Omnimic or XTZ? If not, that is really the only way you will know. A general "rule of thumb" might work for you, but you wouldn't know w/o measuring.


Jeff


----------



## Kal Rubinson


1.  Those panels will not do squat for bass.

2.  If you want to know what the issues are so that you can attack them, think about getting a measurement system, like REW.  Consider, also, a good book to inform you on acoustics.


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000#post_22265701
> 
> 
> Do you have a way to measure your room? REW and related gear or maybe Omnimic or XTZ? If not, that is really the only way you will know. A general "rule of thumb" might work for you, but you wouldn't know w/o measuring.
> 
> Jeff


Jeff,


I already bought Tascam 144, ECM 8000 microphone and learning REW. There is steep learning curve, but I am getting better day by day. I will use it to test.


----------



## sukumar




> Quote:
> Originally Posted by *Kal Rubinson*  /t/255432/acoustical-treatments-master-thread/9000#post_22270253
> 
> 
> 1.  Those panels will not do squat for bass.
> 
> 2.  If you want to know what the issues are so that you can attack them, think about getting a measurement system, like REW.  Consider, also, a good book to inform you on acoustics.



I have started testing REW , but still learning to interpret ate. My friend helped to create bass traps shown here. We need to build one more in the back. I did not take photos yet for front wall bass traps. I will ask him to help to build one with 2 inch and one with 4 inch to test. I am using thin galvanized metal as frame. Appreciate if anybody has suggestions on how it can be attached to wall with gap.

https://plus.google.com/u/0/photos/107811778043676490320/albums/5771003652663651985


----------



## johnzm

Hi,


I have a question about treating my room.











I picked up 6 panels, and i setup 2 of them behind the speakers (on each side of the screen) 2 at the first reflection, which happened to be right past that hanging movie poster, and i have 2 left.


the center channel is a X-voce (partial open baffle) and i am not sure if i would be better off putting treatment behind it, under the screen, or using the leftover treatments on the back wall(or possibly a better location?). my couch is about 4 foot off the back wall


any ideas would be appreciated


----------



## pepar

sukumar - woo HOO! Congratulations on stepping up with the preamp, mic and REW as well as the really nice traps!!


Jeff


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000#post_22271720
> 
> 
> sukumar - woo HOO! Congratulations on stepping up with the preamp, mic and REW as well as the really nice traps!!
> 
> Jeff


Thanks Jeff. It is interesting to learn REW and what does graphs really means. I am getting lot of help from hometheatershack. It is matter of time to fully exploit the tool..


----------



## pepar




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/9000#post_22271859
> 
> 
> Thanks Jeff. It is interesting to learn REW and what does graphs really means. I am getting lot of help from hometheatershack. It is matter of time to fully exploit the tool..



Yes, HTS is the home of REW and *the* source for support. The really cool thing I like about it is you measure one time, save the measurement file and use it to produce all of the different graphs.


----------



## Nyal Mellor

If you are starting out with REW read this article that I co-authored with Ethan from RealTraps, if you are more advanced take a look at this white paper which I co-authored with Jeff of HdAcoustics.


----------



## pepar

Thanks for the links, Nyal!


Jeff


----------



## sukumar




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9000#post_22272160
> 
> 
> If you are starting out with REW read this article that I co-authored with Ethan from RealTraps, if you are more advanced take a look at this white paper which I co-authored with Jeff of HdAcoustics.



Thanks for the link. I read this article few months back when I did not know anything about REW. Now, I am understanding better.


----------



## sukumar

I already placed corner super chunk bass traps and front wall floor from side to side bass trap. It really look cool like stage. I did use OC 703. Now I plan to do in the back wall for around 15 feet long. I thought I could use pink stuff that I read has better GFR ( flow).


If I go to Home depot, what exactly I need to ask them to buy the product and approximately how much do you think I can buy it. I have 3 feet space that I can fill. I intend to put in plastic and wrap with cloth. I will make 7 1/2 feet two pieces. This will complete 6 corners out of 12.


----------



## pepar




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/9000#post_22274905
> 
> 
> I already placed corner super chunk bass traps and front wall floor from side to side bass trap. It really look cool like stage. I did use OC 703. Now I plan to do in the back wall for around 15 feet long. I thought I could use pink stuff that I read has better GFR ( flow).
> 
> If I go to Home depot, what exactly I need to ask them to buy the product and approximately how much do you think I can buy it. I have 3 feet space that I can fill. I intend to put in plastic and wrap with cloth. I will make 7 1/2 feet two pieces. This will complete 6 corners out of 12.



Have you noticed improvements in the sound? Typically reducing room ringing at the bottom cleans up the sound from bottom to top. Delicate sounds are especially more audible.


Jeff


----------



## rnrgagne

So nobody knows if wicker could be a suitable frame to contain a circular bass trap?


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000#post_22274945
> 
> 
> Have you noticed improvements in the sound? Typically reducing room ringing at the bottom cleans up the sound from bottom to top. Delicate sounds are especially more audible.
> 
> Jeff



I watched briefly dishnetwork and felt good about the sound. However, I need to test with blu-ray content. We are going to make absorpton panels this week end. Our back wall is close to seating as shown here.
 


we will plan to use 2 oc 703 with 1 1/2 inch gap panels. I am waiting to complete and start enjoying. I also liked video picture very well with black velvet surrounding the screen except ceiling. It is worth the effort.. We also need to cover back basstraps with velvet.


----------



## pepar




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/9000#post_22275617
> 
> 
> I watched briefly dishnetwork and felt good about the sound. However, I need to test with blu-ray content.



I'd recommend music with a prominent bass guitar, tight bass drum and larger floor toms. For this, my "go to" song is Fourplay's "Chant" from the "Between The Sheets" album. It is only a stereo CD, but with the first large floor tom slam I can hear what my system and room are doing from bottom to top. (Any initial strike of percussion, even LF ones, will have mid- and HF-frequency content.) Try it! For me, and the others in our small home theater group, when this one song sounds good, everything does.


We attended a Fourplay concert recently and got a chance to meet the band during a CD signing session and I told Bob James what I just posted and he commented that the engineer had spent a lot of time getting the mic'ing just right. That made perfect sense.


Jeff


----------



## CruelInventions




> Quote:
> Originally Posted by *rnrgagne*  /t/882655/dont-seperates-kill-even-the-best-receiver/120_60#post_11215516
> 
> 
> *That wicker basket gives me an idea for WAF approved bass-traps!!! Got to give that some more thought.* ....



5 years later...



> Quote:
> Originally Posted by *rnrgagne*  /t/255432/acoustical-treatments-master-thread/9000_60#post_22262415
> 
> 
> I don't plan on just plunking wicker baskets around the room willy-nilly, I'm actually thinking of using them as material to build architectural columns, perhaps with lighting incorporated into them, or as plant holders etc... *I'm just in the infancy of thinking this through and just have loose concepts right now.*
> 
> So I still would like to know how small a circular corner bass trap can be to have a degree of effectiveness.



I've seen one-legged turtles move faster than you.


----------



## DanLW




> Quote:
> Originally Posted by *johnzm*  /t/255432/acoustical-treatments-master-thread/9000#post_22271622
> 
> 
> Hi,
> 
> I have a question about treating my room.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I picked up 6 panels, and i setup 2 of them behind the speakers (on each side of the screen) 2 at the first reflection, which happened to be right past that hanging movie poster, and i have 2 left.
> 
> the center channel is a X-voce (partial open baffle) and i am not sure if i would be better off putting treatment behind it, under the screen, or using the leftover treatments on the back wall(or possibly a better location?). my couch is about 4 foot off the back wall
> 
> any ideas would be appreciated



I'd say experiment between putting the last two at the first reflection of the center channel, or on the back wall. Or maybe at the first reflection of each opposite speaker. What I mean by that is for the left speaker, find the first reflection on the right wall. Same goes for the right speaker.


As I understand, for home theater with multiple seating positions, it's best to treat the side walls entirely with treatments going a little above ear height, and back to the listening position. This way it covers all the reflections for all the speakers and all the listening positions. But if you aren't doing DIY treatments, it gets expensive quick. Especially if you go ahead and make the entire front wall dead, which I have also seen suggested. Treatments on the back wall are a good finishing touch. As I understand, if your speakers are "bright", that can help smooth them out.


The above are some guidelines I've gleaned if you want to make a theater with no bad seats, but no great seat. If you are only concerned about one individual listening position, and want to create a "seat of excellence", then just find each reflection for each speaker and treat those areas.


----------



## sukumar




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000#post_22275713
> 
> 
> I'd recommend music with a prominent bass guitar, tight bass drum and larger floor toms. For this, my "go to" song is Fourplay's "Chant" from the "Between The Sheets" album. It is only a stereo CD, but with the first large floor tom slam I can hear what my system and room are doing from bottom to top. (Any initial strike of percussion, even LF ones, will have mid- and HF-frequency content.) Try it! For me, and the others in our small home theater group, when this one song sounds good, everything does.
> 
> We attended a Fourplay concert recently and got a chance to meet the band during a CD signing session and I told Bob James what I just posted and he commented that the engineer had spent a lot of time getting the mic'ing just right. That made perfect sense.
> 
> Jeff


Thanks Jeff for providing the material. I will get it and test.


----------



## pepar




> Quote:
> Originally Posted by *sukumar*  /t/255432/acoustical-treatments-master-thread/9000#post_22277496
> 
> 
> Thanks Jeff for providing the material. I will get it and test.



Play it loud!


----------



## rnrgagne




> Quote:
> Originally Posted by *CruelInventions*  /t/255432/acoustical-treatments-master-thread/9000#post_22276534
> 
> 
> 5 years later...
> 
> I've seen one-legged turtles move faster than you.



OUCH!!! But true. I tend to over-think and under execute. I'm a highly motivated procrastinator.










Like all projects, I need the first domino to fall and then I get going, and that's usually cleaning out the gargage so I have room to work....


----------



## CruelInventions

I tease, but I'm this side of horrendous on the procrastination scale myself. Reassuring to see someone else with the same malady.

















I only found that because I was doing a search on AVS for wicker and bass traps as I know the subject has come up a few times before. Nothing substantial turned up in the search results in the short time I was seeking the info. A couple members or former members had done something like that, apparently. But without much detail or pictures provided. But again, it was just a quick search so maybe something more substantial would have turned up eventually.


----------



## rnrgagne

Did the same search before posting here with little results. My thinking is something along the lines of using a couple or more baskets to build a tower/s with a similar circumference lamp shade & light somewhere in the lower part for ambient lighting. Or using smaller towers as plant holders etc...

I imagine unfinished wicker baskets would be easy to spray paint or stain to match decor and I'm assuming they would be acoustically transparent enough for bass trapping if the weave is not too tight.


----------



## giomania




> Quote:
> Originally Posted by *rnrgagne*  /t/255432/acoustical-treatments-master-thread/9030#post_22278346
> 
> 
> Did the same search before posting here with little results. My thinking is something along the lines of using a couple or more baskets to build a tower/s with a similar circumference lamp shade & light somewhere in the lower part for ambient lighting. Or using smaller towers as plant holders etc...
> 
> I imagine unfinished wicker baskets would be easy to spray paint or stain to match decor and I'm assuming they would be acoustically transparent enough for bass trapping if the weave is not too tight.



I was thinking they might also provide some diffusion for high-frequencies, given the weave?


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/9030#post_22282546
> 
> 
> I was thinking they might also provide some diffusion for high-frequencies, given the weave?
> 
> Mark


I am not an acoustician nor did I stay ...


I would think that bass frequencies would pass through wicker while some, minor, diffusion of HF would occur. But I'd further think that the latter would be so slight as to be insignificant. Here's a test. find a wicker waste basket, put it over your head and listen to some music. What do you hear and what don't you hear?


And we want pictures of you doing the test!










Jeff


----------



## rnrgagne

I hear my wife laughing! Not sure what frequency that is, I want to say.... "often"?










All kidding aside, it seems like a simple but effective idea.


----------



## giomania




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9030#post_22282596
> 
> 
> I am not an acoustician nor did I stay ...
> 
> I would think that bass frequencies would pass through wicker while some, minor, diffusion of HF would occur. But I'd further think that the latter would be so slight as to be insignificant. Here's a test. find a wicker waste basket, put it over your head and listen to some music. What do you hear and what don't you hear?
> 
> And we want pictures of you doing the test!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Jeff





> Quote:
> Originally Posted by *rnrgagne*  /t/255432/acoustical-treatments-master-thread/9030#post_22282902
> 
> 
> I hear my wife laughing! Not sure what frequency that is, I want to say.... "often"?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> All kidding aside, it seems like a simple but effective idea.



Jeff,


I think you are on to something, but to take it to the next level, how about this:


Set up a calibrated microphone at the LP

Place subject wicker basket over the top of the microphone

Play whatever appropriate measurement tones

Measure


Does it sound like I am a basket-case? On second thought, don't answer that...










Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/9030#post_22283299
> 
> 
> Jeff,
> 
> I think you are on to something, but to take it to the next level, how about this:
> 
> Set up a calibrated microphone at the LP
> 
> Place subject wicker basket over the top of the microphone
> 
> Play whatever appropriate measurement tones
> 
> Measure



Well, if a test for "acoustically transparent" is to blow through cloth, wouldn't it make sense that _hearing_ through wicker would also be valid?


Back to the humor/humour of some aspects of audionerditis, Youtube video of this test would be precious. I bet it could go viral!


Jeff


----------



## lbrown105

I have a question about ceiling reflections and the use of fiberglass insulation batting. Recently I replaced some of the drop ceiling tiles in my home theater with framed black cloth tiles. The cloth is acoustically transparant and the batting above is being used as absorber. My question is the batting has the thin plastic covering which helps make it less messing. How critical to remove that to get the high freq absorption. I do not have measuring equipment but when I hold a piece of the thin plastic covering over my speaker it only attenuates the very highest freq. Does that probably mean thos freq are being reflected? I dread removing that platic because it is so messy. I hate going up into that ceiling at all but I will if it is going to make a big difference.


----------



## pepar

I'm pretty sure you don't want the highs bouncing around up there and then re-entering your room.


----------



## lbrown105

I was afraid you were going to say that. I really appreciate the feedback, now where did I leave my hazmat suit?


----------



## pepar




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9030#post_22287142
> 
> 
> I was afraid you were going to say that. I really appreciate the feedback, now where did I leave my hazmat suit?


Tell me, do the hazmat suits there have cheese heads?


----------



## lbrown105

no but they should because cheese heads usually have a beer holder with a straw for hands free enloyment of ones beverage and I could have used that while working on the ceiling tonite. Anyway I was able to take some extra acoustimac absorption material I had and get it place between the ceiling tiles and the plastic covered insulation. problem solved room sounds good thanks for the advice


----------



## pepar




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9030#post_22288276
> 
> 
> no but they should because cheese heads usually have a beer holder with a straw for hands free enloyment of ones beverage and I could have used that while working on the ceiling tonite. Anyway I was able to take some extra acoustimac absorption material I had and get it place between the ceiling tiles and the plastic covered insulation. problem solved *room sounds good* thanks for the advice


Excellent!


----------



## sukumar

I am planning to make absorption panels 5 to 6 of 4inch Owen corning 703 with 2 inch gap. I will wrap in 4oz polyester batting and put stretch velvet cloth. Appreciate any feedback. I am hoping that it would absorb high frequency reflections and do some bass traps.


----------



## KasabeHD

I am at loss of understanding why some speaker manufactures suggest sometimes 10-12 inches of space between the front LCR's and the back of a Stewart Microperf screens, while some well-known speaker mfg say its not necessary except for an inch or two. And How do the cinemasonic processors Stewart provides work or take into account the distance the speakers are from the back side of the screen?


----------



## pepar

I think it's because perfed screens can be afflicted with comb-filtering (from some of the sound bouncing off the rear of the screen and interacting with the direct sound. Some then will bounce off the face of the speaker and interact with the sound that just bounced off off the screen. When I had a perfed screen, I made and applied a mask to reduce/eliminate that. It is imperative that the entire cavity behind the screen be properly treated and the "bouncing" sound can be between the wall and the screen rear. Woven screens don't seem to have a problem with comb-filtering.


My understanding of the Stewart processor is that is merely lifts the higher frequencies to compensate for the loss due to the perfed screen. But no EQ, not even the Stewart one can correct comb-filtering.


The newer generation of Stewart screens Microperf2 have smaller holes and more of them to allow more sound to pass. But the effect is still present. Personally, I would never own anything but a woven screen.


Jeff


----------



## Dennis Erskine

There are two recommendations you'll find ... one from StewartFilmscreen and the other you MAY find from a speaker manufacturer. If a speaker manufacturer is suggesting a value different Stewart, ask for their internal test results.


The processor provided by Stewart (at no additional cost) is designed to compensate for the High Frequency roll off which occurs when speakers are placed behind their screen. Please note, placing anything in front of a speaker will result in varying amounts of HF roll off...including air...which is a significant problem with long throw distances in home theaters.


Further, any screen, woven or otherwise, will reflect sound energy off the back of the screen. These back reflections must be "terminated" (usually with absorptive treatments behind the screen). While there is a bunch of unsubstantiated arm waving about comb filtering from Stewart MicroPerf screens (usually from manufacturers of competing products). Tests by accredited organizations poo-poo this suggestion.


----------



## au-734

Wouldn't something like Audyssey perform the same, or similar compensation for the HF rolloff?


----------



## pepar

Dennis - do you have links to those "accredited organizations" and their reports?


I know that in my theater, going from a Stewart Microperf screen to a woven design noticeably improved my sound. Everyone can take that or not.


As I understand it, while the Microperf2 holes are very small, "non-screen" parts of a woven screen are a lot smaller with a lot more of them. Essentially, there is more open area for sound to pass. More sound passes, less is reflected. And of course, back reflections need to be terminated. I never implied that there were no reflections and the cavity behind a woven screen did not need treating.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *au-734*  /t/255432/acoustical-treatments-master-thread/9030#post_22323225
> 
> 
> Wouldn't something like Audyssey perform the same, or similar compensation for the HF rolloff?


Yes.


----------



## Dennis Erskine




> Quote:
> I know that in my theater, going from a Stewart Microperf screen to a woven design noticeably improved my sound.


That would be a matter of proper calibration. The sound will change but for better or worse will vary from room to room.

Also...the more air which moves through the screen, the less the light gets reflected back to the seating area (there's your compromise) and the other down side could be the available screen coatings and reflectivity characteristics of the screen coatings available from woven vs Stewart screen materials.


Audyssey may or may not address the HF roll off. Audyssey is going to look at the total HF spectra at the seating location(s) and make some adjustments; however, like all automagic systems, they are very conservative in that area so they don't end up boosting the HF domain to the extent your drivers get overheated and damaged. Just saying.


----------



## rmaddog

So I was told to post this here to get the best responses.


I tried searching for tips on how and why this is done but couldn't find much of anything, not sure if I am not using the right terminology or what to find what I am looking for. I have read some stuff about splayed walls (going the length of the room) and I may consider that but I was in an auditorium today where the side walls were angled / slanted inwards. I assume this was done for acoustically reasons... I am not sure what this 'architectural' technique is called but wondering if there is anyone that has any experience in this area that can give any advice like how helpful it is with acoustics, what angle(s) need to be used to be effective, etc. I guess this could be considered a splayed wall but it goes from the ceiling to the floor. I read that with splayed walls you would want a 6 degree angle on each wall to get the acoustic benefit. It seems that it would be fairly easy to do by having the top plate of your framing moved inwards in the room (not being directly plumb above the bottom plate) and possibly mitering the top and bottom stud to fit the angle.


Made a quick sketch to display visually what I am talking about:

 


The top pic is just a normal room with 180 degree vertical walls with columns and a soffit. The bottom pic has the angled walls and where you can see the columns not protrude out of the wall as much because the wall is slanted in as you go up to the ceiling.


Rob


----------



## pepar




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9030#post_22323558
> 
> 
> That would be a matter of proper calibration. The sound will change but for better or worse will vary from room to room.


Sure, there was nothing scientific about my experience. And I might have heard an improvement because I expected to.


> Quote:
> Also...the more air which moves through the screen, the less the light gets reflected back to the seating area (there's your compromise) and the other down side could be the available screen coatings and reflectivity characteristics of the screen coatings available from woven vs Stewart screen materials.


Yup, upsides and downsides to both. Gain is limited with woven, though I *think* the latest generation has improved on that aspect.


----------



## NicksHitachi




> Quote:
> Originally Posted by *au-734*  /t/255432/acoustical-treatments-master-thread/9030#post_22323225
> 
> 
> Wouldn't something like Audyssey perform the same, or similar compensation for the HF rolloff?


Audyssey typically rolls off the high end anyways, so with a good woven you might lose 0.5-1.0db in the last upper ocatave.  Audyssey's target is even more rolled off than that so you wouldn't see any boost by Audyssey as a result of the screen itself.  Unless you turn off Dynamic EQ that is....


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9030#post_22326230
> 
> 
> Audyssey typically rolls off the high end anyways, so with a good woven you might lose 0.5-1.0db in the last upper ocatave.  Audyssey's target is even more rolled off than that so you wouldn't see any boost by Audyssey as a result of the screen itself.  Unless you turn off Dynamic EQ that is....



That's probably true. MultEQ begins rolling off at 10k and bends the slope more, I believe, at 16K. DEQ only boosts highs and lows when the MV is below reference, so while the highs may be "relatively" boosted, highly unlikely that the tweets are being stressed.


Jeff


----------



## Kal Rubinson




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9030#post_22326230
> 
> 
> Audyssey typically rolls off the high end anyways, so with a good woven you might lose 0.5-1.0db in the last upper ocatave.


 


> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9030#post_22326635
> 
> 
> That's probably true. MultEQ begins rolling off at 10k and bends the slope more, I believe, at 16K.


It depends on the version of MultEQ that you have.  Some offer a flat response option.


----------



## KasabeHD

From reading the white papers on Microperf from Stewart. To obtain the best acoustical transparency of a Microperf screen, the loudspeaker (all loudspeakers regardless of brand, assuming all direct radiating) should be placed a minimum of 12" away from the back of the perforated screen and the active Cinemasonic processors should always be used to restore the 10k -20khz attenuation. This method has been studied and proven by THX labs to ensure the best acoustical transparency. I am totally ok following this method, which solves my acoustical concerns, and allows me to enjoy the far superior visual performance of a Stewart screen over a woven screen. Which having seen both side by side, I do not feel woven looks as good (I understand this is my personal opinion)


However, my concern is when the design of the room does NOT allow for 12" of space behind the screen and say your limited to 1 or 2 inches and your set on staying with Stewart Microperf. What is the expected comb filtering effects and what solutions are there to correct it. It would be nice to see the data that THX did that ultimately convinced them to set the minimum at 12". I would like to see the data that shows audio performance when they set the same speaker at 1" from the screen. (I am sure that exist somewhere). Or I can take the data some of the woven screen manufactures use to show the attenuation of perfed screens in their marketing literature, as they seem to never test the speaker at 12" usually its 4 inches or less, and use it to get some idea. I guess at that point the SIMPLIEST solution is to remove the Cinemasonic processors (which are designed to work at 12") and rely on the Audyssey to correct, as best possible. Or a more advanced approach to break out the Goldline and try to manually adjust those frequencies as best you can. I don't know.


As much as I respect Triad, I have been told by them to disregard the 12" of distance on Stewart Microperf, that is perfectly ok to be 2-3 inches from the screen. How can that be? For now, I will default to Stewarts recommendation's in all case where I can permit 12", but remain curious.


----------



## pepar




> Quote:
> Originally Posted by *Kal Rubinson*  /t/255432/acoustical-treatments-master-thread/9030#post_22326641
> 
> 
> It depends on the version of MultEQ that you have.  Some offer a flat response option.


Kal, I don't think Audyssey Flat is ... flat. It just doesn't apply the same degree of slope needed to hit their home theater interpretation of the X-Curve (or whatever it's called).


Or am I wrong on that?


Jeff


----------



## NicksHitachi




> Quote:
> Originally Posted by *Kal Rubinson*  /t/255432/acoustical-treatments-master-thread/9030#post_22326641
> 
> 
> 
> 
> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9030#post_22326230
> 
> 
> Audyssey typically rolls off the high end anyways, so with a good woven you might lose 0.5-1.0db in the last upper ocatave.
> 
> 
> 
> 
> 
> 
> 
> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9030#post_22326635
> 
> 
> That's probably true. MultEQ begins rolling off at 10k and bends the slope more, I believe, at 16K.
> 
> Click to expand...
> 
> It depends on the version of MultEQ that you have.  Some offer a flat response option.
Click to expand...

Good Point.  I don't have a "flat" option per say, but if I disengage Dynamic EQ the response goes back to flat(Onkyo).  I leave it on as I can't hear much beyond 15K and I enjoy the house curve it provides.  Additionaly I currently don't use high efficiency mains and those 1" silk domes just aren't capable of 105db explosions at the LP so its probably good that Audyssey does it from a safety and sound quality stand point.

 

Its rolled off considerably, as mentioned by pepar, above 10K way beyond what the screen induces.  I doubt any positive EQ boost/gain on my setup attributable to the AT screen while Dynamic EQ is on, in the frequency range which the woven screen is guilty of attenuation.

 

I can appreciate the concern for those running a "flat" setting.


----------



## pepar




> Quote:
> Originally Posted by *KasabeHD*  /t/255432/acoustical-treatments-master-thread/9030#post_22326646
> 
> 
> For now, I will default to Stewarts recommendation's in all case where I can permit 12", *but remain curious*.



"Suspicious" would be a more prudent posture. While Stewart may have data that shows deterioration as the distance falls below 12", they will never show it.


Perhaps, if you have 12" and need the gain of a perfed solution, Stewart is the way to go. But if either is not present, perhaps the decision should go towards woven? Either way, don't expect the woven mongers to help make the case for perfed or vice versa.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9030#post_22326718
> 
> 
> Good Point.  I don't have a "flat" option per say, but if I disengage Dynamic EQ the response goes back to flat(Onkyo).  I leave it on as I can't hear much beyond 15K and I enjoy the house curve it provides.  Additionaly I currently don't use high efficiency mains and those 1" silk domes just aren't capable of 105db explosions at the LP so its probably good that Audyssey does it from a safety and sound quality stand point.
> 
> 
> Its rolled off considerably, as mentioned by pepar, above 10K way beyond what the screen induces.  I doubt any positive EQ boost/gain on my setup attributable to the AT screen while Dynamic EQ is on, in the frequency range which the woven screen is guilty of attenuation.
> 
> 
> I can appreciate the concern for those running a "flat" setting.



Nick, turning DEQ off doesn't get you "flat." But engaging a THX mode and defeating THX Re-EQ does. Audyssey switches to "flat" when in a THX mode to avoid duplication of what Re-EQ does. So this is a workaround. I never use this though as I have Audyssey Pro and have created a custom target curve that lifts the high end a wee bit. Trust me, you really don't want flat as it is way too harsh. At least in my theater.


Sorry for being OT ...


Jeff


----------



## Dennis Erskine

...and, if you look at the roll off in the microperf screens, you'll find it a close match to what Re-EQ does or the house "X" curve.


----------



## pepar

Isn't the concern with AT screens - and maybe perfed ones in particular - comb-filtering and not attenuation? The latter can be corrected if necessary.


----------



## KasabeHD

Good point. Correct me if I am wrong, but you cant fix comb filtering, those frequencies affected by comb filtering are lost. As opposed to attenuation of those frequencies, which can be corrected by adjusting, increasing the level by the level of attenuation. So, it would make no point to move the speaker less than 12" from the back of the screen as effects of comb filtering would negate any logical reason for doing so. In that case, I can see the reasoning for considering woven,as the effects of comb filtering, are presumably lower, when the screen has to be very close to the front the speaker. It's all becoming a bit clearer. IF the above statement is true, Then NO speaker manufacture should recommend placing there speakers any closer than 12" when using a Stewart perforated screen.


----------



## giomania




> Quote:
> Originally Posted by *KasabeHD*  /t/255432/acoustical-treatments-master-thread/9000_100#post_22326646
> 
> 
> From reading the white papers on Microperf from Stewart. To obtain the best acoustical transparency of a Microperf screen, the loudspeaker (all loudspeakers regardless of brand, assuming all direct radiating) should be placed a minimum of 12" away from the back of the perforated screen and the active Cinemasonic processors should always be used to restore the 10k -20khz attenuation. This method has been studied and proven by THX labs to ensure the best acoustical transparency. I am totally ok following this method, which solves my acoustical concerns, and allows me to enjoy the far superior visual performance of a Stewart screen over a woven screen. Which having seen both side by side, I do not feel woven looks as good (I understand this is my personal opinion)
> 
> 
> As much as I respect Triad, I have been told by them to disregard the 12" of distance on Stewart Microperf, that is perfectly ok to be 2-3 inches from the screen. How can that be? For now, I will default to Stewarts recommendation's in all case where I can permit 12", but remain curious.



Some questions that popped into my head regarding your issue:


What is the date of the Stewart white paper, and when was the concurrent research conducted?

When were the Triad speakers under consideration designed?


If the research was conducted before Triad designed the speakers, and Triad was aware of this research and the practical limitations of having 12" of space behind the screen, is it possible the speakers were designed with placement behind a Stewart micro-perf screen in mind? This is probably doubtful and unlikely, but I thought I would throw it out there to see if it stuck.


Regarding Stewart screens versus all others (woven or non-woven), I always look at what the professional reviewers that are published in magazines use. Anyone can publish a review on the internet, which is the reason for my clarification. Anyway, the last time I checked, Greg Rogers and Tom Norton both use Stewart StudioTek 130 screens. Now, some might say they are old dogs that cannot be taught new tricks. However, I am sure they are hitting the trade shows, looking at all the new screens, and saying "Ummm...no thanks". I realize this is pure conjecture and my opinion.


Mark


----------



## pepar




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/9060#post_22327544
> 
> 
> Some questions that popped into my head regarding your issue:
> 
> What is the date of the Stewart white paper, and when was the concurrent research conducted?
> 
> When were the Triad speakers under consideration designed?
> 
> If the research was conducted before Triad designed the speakers, and Triad was aware of this research and the practical limitations of having 12" of space behind the screen, is it possible the speakers were designed with placement behind a Stewart micro-perf screen in mind? This is probably doubtful and unlikely, but I thought I would throw it out there to see if it stuck.
> 
> Regarding Stewart screens versus all others (woven or non-woven), I always look at what the professional reviewers that are published in magazines use. Anyone can publish a review on the internet, which is the reason for my clarification. Anyway, the last time I checked, Greg Rogers and Tom Norton both use Stewart StudioTek 130 screens. Now, some might say they are old dogs that cannot be taught new tricks. However, I am sure they are hitting the trade shows, looking at all the new screens, and saying "Ummm...no thanks". I realize this is pure conjecture and my opinion.
> 
> Mark



How would a speaker's design be altered so that a perforated mask in front of it will not cause comb-filtering in the room where the listeners are?


I wouldn't by default trust a "professional" reviewer over an "internet reviewer." And the more "professional" they are, the more they *might* be corporate types whose opinions are ... I should stop. Bottom line: Trust, but verify.










BTW, I completely trust Kalman. Let's see what he says! [/ingratiating comments]


Jeff


----------



## NicksHitachi




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9060#post_22327643
> 
> 
> How would a speaker's design be altered so that a perforated mask in front of it will not cause comb-filtering in the room where the listeners are?


 

Possibly by using speaker designs which contro. directivity which by default helps comb filtering?  I'm personally of the opinion that controlled directivity speakers are the only way to go behind a AT screen, IMHO.


----------



## giomania




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9000_100#post_22327643
> 
> 
> How would a speaker's design be altered so that a perforated mask in front of it will not cause comb-filtering in the room where the listeners are?
> 
> I wouldn't by default trust a "professional" reviewer over an "internet reviewer." And the more "professional" they are, the more they *might* be corporate types whose opinions are ... I should stop. Bottom line: Trust, but verify.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> BTW, I completely trust Kalman. Let's see what he says! [/ingratiating comments]
> 
> Jeff



I thought about that after I posted the comment.







Oh well, neither idea stuck to the wall...at least in this thread!


Mark


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9060#post_22327713
> 
> 
> Possibly by using speaker designs which contro. directivity which by default helps comb filtering?  I'm personally of the opinion that controlled directivity speakers are the only way to go behind a AT screen, IMHO.



You are thinking controlling directivity, i.e. limiting off-axis output, helps? That's interesting, but I don't see how.


----------



## NicksHitachi


I'm basing this on the premise that other AT fabrics exhibit different levels of transparency with respect to the angle of incidence.  I'm picturing controlled diirectivity energy having more of a perpendicular incidence and therefore less deflection/reflection.  Straight through a hole the cross section may be big enough to be AT, however at other angles the hole becomes progressively smaller to the point of zero depending upon incidence angle......  Therefore the off axis energy could be EQed based on this, right?

 

I don't know of any studies on this, just thinking out loud really.

 

Conceptually, I always thought the lower the off axis energy to be bounced around behind the screen and arrive out of phase the better.

 

What about diffraction of the off axis energy as it passes through the holes at extreme angles?


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9060#post_22328405
> 
> 
> I'm basing this on the premise that other AT fabrics exhibit different levels of transparency with respect to the angle of incidence.  I'm picturing controlled diirectivity energy having more of a perpendicular incidence and therefore less deflection/reflection.  Straight through a hole the cross section may be big enough to be AT, however at other angles the hole becomes progressively smaller to the point of zero depending upon incidence angle......  Therefore the off axis energy could be EQed based on this, right?
> 
> 
> I don't know of any studies on this, just thinking out loud really.
> 
> 
> Conceptually, I always thought the lower the off axis energy to be bounced around behind the screen and arrive out of phase the better.
> 
> 
> What about diffraction of the off axis energy as it passes through the holes at extreme angles?


Of course, this is Thinking Out Loud Theater. There's the sound that can bounce between screen back and speaker face and comb filter, and then there's the sound that squeezes through all the little holes and out into the theater. My understanding, and admittedly that is being kind to me, every one of those little holes is essentially a sound source the RECOMBINING OF WHICH causes comb filtering.


The difference between THX Microperf and THX Microperf2 is that they decreased the size of the holes and increased their number. Following this thinking, a woven screen has a lot smaller holes and a LOT MORE of them. By the Microperf vs Microperf2 thinking, strictly for sound quality, this would seem to be even better. Right, or did I miss something?


Dennis' earlier points about gain now come into play WRT the pluses and minuses of perfed and woven. But I just don't see how, if you are not lumenally challenged, a woven screen would not be the best choice.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9060#post_22328405
> 
> 
> 
> Conceptually, I always thought the lower the off axis energy to be bounced around behind the screen and arrive out of phase the better.
> 
> 
> What about diffraction of the off axis energy as it passes through the holes at extreme angles?



That off-axis radiation strike the screen at a low angle and then would strike the treatments, be absorbed and badda boom, badda bing, end of story. As I mentioned, it is the sound that goes into the room through all the little holes and recombines that cause the problem.


----------



## Kal Rubinson




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9030#post_22326711
> 
> 
> 
> Kal, I don't think Audyssey Flat is ... flat. It just doesn't apply the same degree of slope needed to hit their home theater interpretation of the X-Curve (or whatever it's called).
> 
> Or am I wrong on that?
> 
> Jeff


No?  It is not offered on all products but I would be surprised if it was not.


----------



## aharami

Just starting to research this stuff, so apologize in advance if the following questions have been asked a thousand times already.


I was introduced to acoustic panels by a member in another forum. He creates a backer frame where the OC703 rests on the frame instead of being placed inside it
http://forums.anandtech.com/showpost.php?p=29012837&postcount=53 

I was thinking of placing the OC703 inside the frame and covering the back with 1/8" thick hardboard instead of fabric. This will be cheaper and give the frame more structural rigidity. His method has the OC703 couple inches away from the wall, whereas my method would have the OC directly against a hard surface (hardboard and wall).


What are the benefits of creating a backer frame instead of having a frame around the OC?

And for non bass trap treatments, is it beneficial to have some airspace between the OC and a reflective surface (wall or hardboard)?


----------



## erkq

I'm interested in thoughts on this. This got lost in the screen discussion. I was thinking of a similar setup to keep echos at bay. Effective?


> Quote:
> Originally Posted by *rmaddog*  /t/255432/acoustical-treatments-master-thread/9030#post_22324016
> 
> 
> So I was told to post this here to get the best responses.
> 
> I tried searching for tips on how and why this is done but couldn't find much of anything, not sure if I am not using the right terminology or what to find what I am looking for. I have read some stuff about splayed walls (going the length of the room) and I may consider that but I was in an auditorium today where the side walls were angled / slanted inwards. I assume this was done for acoustically reasons... I am not sure what this 'architectural' technique is called but wondering if there is anyone that has any experience in this area that can give any advice like how helpful it is with acoustics, what angle(s) need to be used to be effective, etc. I guess this could be considered a splayed wall but it goes from the ceiling to the floor. I read that with splayed walls you would want a 6 degree angle on each wall to get the acoustic benefit. It seems that it would be fairly easy to do by having the top plate of your framing moved inwards in the room (not being directly plumb above the bottom plate) and possibly mitering the top and bottom stud to fit the angle.
> 
> Made a quick sketch to display visually what I am talking about:
> 
> 
> The top pic is just a normal room with 180 degree vertical walls with columns and a soffit. The bottom pic has the angled walls and where you can see the columns not protrude out of the wall as much because the wall is slanted in as you go up to the ceiling.
> 
> Rob


----------



## FOH




> Quote:
> Originally Posted by *aharami*  /t/255432/acoustical-treatments-master-thread/9060#post_22368419
> 
> 
> What are the benefits of creating a backer frame instead of having a frame around the OC?
> 
> And for non bass trap treatments, is it beneficial to have some airspace between the OC and a reflective surface (wall or hardboard)?



Ideally, bass trap or reflection panel, you don't typically want a backer panel of significant thickness on the treatment panel,...because you're best served by a nice bit of spacing off the boundary surface.


For thinner panels of about 4" minimum (ideally 6"-8"), you're best served with a significant air gap behind the panel and in front of the boundary surface as this is essentially as good as a much thicker panel. So as much space behind the panel as you can give up works wonders in effectively lowering the effective frequency coverage of the panel.


Now, if you're interested in very thick, effective bass traps, greater than 8", you switch to inexpensive fluffy fiberglass. That's great because it's both more effective and cheaper than rigid fiberglass or something like Roxul Safe-n-Sound.


Back on topic; yes, .... you increase the effectiveness significantly by _not placing a backer board_ and spacing it just a little off the wall, ceiling, etc.



Good luck


----------



## aharami

thanks!


----------



## rmaddog




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9060#post_22368479
> 
> 
> I'm interested in thoughts on this. This got lost in the screen discussion. I was thinking of a similar setup to keep echos at bay. Effective?



erkq, I started a forum for this here and got some response but was told I might get more feed back on this thread, but haven't had any yet...







I'm fairly new to the forum but Dennis Erskine who seems to be an expert in acoustics realm, doesn't recommend it without having s design/tests done, which I won't be doing... My room is about 2800 cubit feet and the auditorium that I originally saw this in is huge in comparison to it. Don't have exact measurements but it's around 120' L x 60' W x 30' T. So that's 216,000 cubit feet and only some 77 times bigger than my room.







Just wish there was more info about it somewhere, particularly when and how it can become effective as I've found similar info about splayed walls but not this...


----------



## GIK Acoustics




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9060#post_22368479
> 
> 
> I'm interested in thoughts on this. This got lost in the screen discussion. I was thinking of a similar setup to keep echos at bay. Effective?



Flutter echo happens between any two non-treated parallel walls. Absorption can get rid of flutter echo, but if you have the chance to build, then angling the walls will also get rid of flutter echo without making the space too 'dead'. Something a lot of people don't think about in this equation is flutter echo between floors and ceilings. If you have carpet, then you won't have any flutter echo - but if you have hard flooring (wood, cement, tile, etc) you will certainly have flutter echo between those boundaries. Even moreso damaging, the distance between the ceiling and floor is usually the smallest dimension of the room, so there can be significantly more flutter echo between these boundaries. Since most don't have the chance to angle their ceilings, clouds (panels hanging from the ceiling) are very effective in helping the over-all sound in the room, especially with hard flooring.


> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9060#post_22368785
> 
> 
> Ideally, bass trap or reflection panel, you don't typically want a backer panel of significant thickness on the treatment panel,...because you're best served by a nice bit of spacing off the boundary surface.
> 
> For thinner panels of about 4" minimum (ideally 6"-8"), you're best served with a significant air gap behind the panel and in front of the boundary surface as this is essentially as good as a much thicker panel. So as much space behind the panel as you can give up works wonders in effectively lowering the effective frequency coverage of the panel.



+1. All of our panels have an air gap built in. The effectiveness of an added air gap can be seen in corner mounted panels too - although there are many reasons panels work well when straddling corners - one of them is certainly the large air gap you get. If you're straddling a 24" wide trap, you have a 17" air gap at the center of the panel, which is great!


----------



## rmaddog




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9060#post_22372650
> 
> 
> Flutter echo...



GIK Acoustics, thanks for the response! Sometimes you just need the right keyword to get the desired search results... In looking more on flutter echo, I found this article here that has some good but somewhat technical info on acoustics with some stuff about angled walls. I did a lot of my framing this past weekend w/o the vertically angled walls. While I could add angled studs to or in between what I put up, it seems like it would be easier to add/move around some panels as needed for similar acoustic benefits so I am going to go with that route. I think between having a tray soffit, a platform riser, wall columns, several movie poster frames, and built in DVD/Blu-ray shelving will be a start to break up the room a bit from being a flat box and I can add on from there as I hear what I can get out of the room.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *rmaddog*  /t/255432/acoustical-treatments-master-thread/9060#post_22372722
> 
> 
> GIK Acoustics, thanks for the response! Sometimes you just need the right keyword to get the desired search results... In looking more on flutter echo, I found this article here that has some good but somewhat technical info on acoustics with some stuff about angled walls. I did a lot of my framing this past weekend w/o the vertically angled walls. While I could add angled studs to or in between what I put up, it seems like it would be easier to add/move around some panels as needed for similar acoustic benefits so I am going to go with that route. I think between having a tray soffit, a platform riser, wall columns, several movie poster frames, and built in DVD/Blu-ray shelving will be a start to break up the room a bit from being a flat box and I can add on from there as I hear what I can get out of the room.



Glad I was able to help! Flutter echo is horribly annoying - but luckily for us, probably the easiest acoustic problem to treat.


----------



## Anhydro

I have read through the early pages of this thread and have looked at http://www.bobgolds.com/AbsorptionCoefficients.htm aborption coefficients. I am in the process of building a 17W' X 20'L X 9'H dedicated basement home. I have purchased eight 2' X 4' panels from ATS (2" thick and filled with Roxul AFB Mineral Wool... http://www.atsacoustics.com/item--ATS-Acoustic-Panel-24x36x2--1046.html ,which have a stated NRC of .95. I'm also treating the area behind my acoustically transparent screen (covering most of the front wall) and my soffits (which surround the room at 12" X 12") with 1" thick CertainTeed ToughGuard R (which has same.70 NRC rating as Linacoustic RC, OC 703, and InsulShield, etc). Six of the panels will be place at first reflections points of the side walls (3 on each) and two panels horizontally placed behind the second row of seats on my back riser. My riser, which is 14' X 6.5' will have holes drilled every 3" across a chalked grid and the inside will be filled with R-13 insulation. *I am hesitant to do anything more at this point and am somewhat concerned I may have done too much. I would appreciate any advice... I still have a bit of time to make changes... but not much.* Thanks!


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9060#post_22379262
> 
> 
> I have read through the early pages of this thread and have looked at http://www.bobgolds.com/AbsorptionCoefficients.htm aborption coefficients. I am in the process of building a 17W' X 20'L X 9'H dedicated basement home. I have purchased eight 2' X 4' panels from ATS (2" thick and filled with Roxul AFB Mineral Wool... http://www.atsacoustics.com/item--ATS-Acoustic-Panel-24x36x2--1046.html ,which have a stated NRC of .95. I'm also treating the area behind my acoustically transparent screen (covering most of the front wall) and my soffits (which surround the room at 12" X 12") with 1" thick CertainTeed ToughGuard R (which has same.70 NRC rating as Linacoustic RC, OC 703, and InsulShield, etc). Six of the panels will be place at first reflections points of the side walls (3 on each) and two panels horizontally placed behind the second row of seats on my back riser. My riser, which is 14' X 6.5' will have holes drilled every 3" across a chalked grid and the inside will be filled with R-13 insulation. *I am hesitant to do anything more at this point and am somewhat concerned I may have done too much. I would appreciate any advice... I still have a bit of time to make changes... but not much.* Thanks!



I don't think that you have gone overboard. If anything, I would suggest buying more - not to treat more surface area - but to make the current traps thicker. 1" and 2" thick traps hardly touch the bass region at all. They will help the overall sound I'm sure, but thicker will help treat the lower end of the frequency spectrum. You do have the riser being stuffed, which should help tremendously for bass absorption. (How tall is the riser?)


Adding air gaps between the panel and the wall (that is, spacing it off the wall) will also extend the working frequency range of the panels, so I would recommend that as well. Lastly, the NRC doesn't tell you much about these products, or what they absorb. For example, a certain material can have an absorption coefficient of 1.5 at a certain frequency, but 0.1 at another, and the NRC is the average of all the 1/3 octave bands (except the highest and lowest ones, 125Hz and 8kHz). You should be looking at the absorption coefficients per frequency band so you can see what frequencies you are effecting. NRC is really only used for determining the sound dampening qualities the product has on speech frequencies, not 40 Hz bass rumbling we hear in movies all the time - not to mention music!


----------



## FOH




> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9060#post_22379262
> 
> *I am hesitant to do anything more at this point and am somewhat concerned I may have done too much. I would appreciate any advice... I still have a bit of time to make changes... but not much.* Thanks!



You want as much bass trapping as you can get.


Diffuse/scatter the rear wall, unless you're seated close to it then absorb it fully (8"-12" of treatment).


The places you need to concern yourself about overly deadening are typically the sidewalls, and there you should only hit the areas that reflect your LCRs back to the LP.


So surgical treatment of sidewalls, heavy bass trapping, heavy ceiling treatment between mains and LP, front wall scenarios vary however lessen the SBIR impact by heavy treatment around mains.


A good rule of thumb is if you absorb, you absorb all or nothing,...otherwise you're merely creating a filtered reflection.





Good luck


----------



## Anhydro




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9060#post_22380213
> 
> 
> You want as much bass trapping as you can get.
> 
> Diffuse/scatter the rear wall, unless you're seated close to it then absorb it fully (8"-12" of treatment).
> 
> The places you need to concern yourself about overly deadening are typically the sidewalls, and there you should only hit the areas that reflect your LCRs back to the LP.
> 
> So surgical treatment of sidewalls, heavy bass trapping, heavy ceiling treatment between mains and LP, front wall scenarios vary however lessen the SBIR impact by heavy treatment around mains.
> 
> A good rule of thumb is if you absorb, you absorb all or nothing,...otherwise you're merely creating a filtered reflection.
> 
> Good luck





> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9060#post_22379647
> 
> 
> I don't think that you have gone overboard. If anything, I would suggest buying more - not to treat more surface area - but to make the current traps thicker. 1" and 2" thick traps hardly touch the bass region at all. They will help the overall sound I'm sure, but thicker will help treat the lower end of the frequency spectrum. You do have the riser being stuffed, which should help tremendously for bass absorption. (How tall is the riser?)
> 
> Adding air gaps between the panel and the wall (that is, spacing it off the wall) will also extend the working frequency range of the panels, so I would recommend that as well. Lastly, the NRC doesn't tell you much about these products, or what they absorb. For example, a certain material can have an absorption coefficient of 1.5 at a certain frequency, but 0.1 at another, and the NRC is the average of all the 1/3 octave bands (except the highest and lowest ones, 125Hz and 8kHz). You should be looking at the absorption coefficients per frequency band so you can see what frequencies you are effecting. NRC is really only used for determining the sound dampening qualities the product has on speech frequencies, not 40 Hz bass rumbling we hear in movies all the time - not to mention music!




Many thanks to both of you... very help, indeed! I'm looking at ordering some corner bass traps now. The square footage covered by the acoustic panels is not that great considering the overall size of the room, so I hope I've met the "surgical" standard without over-deading the walls. I guess I can always add more once the room is complete.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9060#post_22380555
> 
> 
> Many thanks to both of you... very help, indeed! I'm looking at ordering some corner bass traps now. The square footage covered by the acoustic panels is not that great considering the overall size of the room, so I hope I've met the "surgical" standard without over-deading the walls. I guess I can always add more once the room is complete.



Corner traps work very well for trapping bass for tons of reasons...definitely a great solution to maintain nice large traps that do a lot of work while not having them be obstructive and in the way. You could always try a tuned pressure absorber if you still need more bass management but don't want to deaden the room any more. I would recommend getting all your treatment set up first though, and then see if you need tuned traps.


----------



## pepar




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9060#post_22380213
> 
> 
> You want as much bass trapping as you can get.
> 
> Diffuse/scatter the rear wall, unless you're seated close to it then absorb it fully (8"-12" of treatment).
> 
> The places you need to concern yourself about overly deadening are typically the sidewalls, and there you should only hit the areas that reflect your LCRs back to the LP.
> 
> So surgical treatment of sidewalls, heavy bass trapping, heavy ceiling treatment between mains and LP, front wall scenarios vary however lessen the SBIR impact by heavy treatment around mains.
> 
> A good rule of thumb is if you absorb, you absorb all or nothing,...otherwise you're merely creating a filtered reflection.
> 
> Good luck



I have been considering replacing some of my first reflection point absorbers (2" OC 703, framed, GOM'd and attached directly to wall) with diffusors. My decay time is a bit short, I think, (200ms) and I think the room is a wee bit to dead. Other than what I just posted, is there any other measurement that I should do to move me ahead with this (or cause me to dismiss the idea)?


Jeff


----------



## eiger

Hi Guys -


I have a dedicated room that I'm experiencing some minor problems with. It's been a long time since I've done a full sweep of the room using REW or any other type of real time anaylysis.

My room has transformed quite a bit over the last year. (Riser was installed, new speakers, new amp, new pre-amp). So lots of new gear.


The room is 26 x 16 x 8. (3300cu ft) It is dedicated with 8 GIK 242s. No Corner Bass Traps. Three panels on each side wall, as well as behind each speaker. One on the ceiling. The problem seems to be emphais on the higher end of the frequency septrum.

What can I do to address this? Because I'm noticing it on the higher frequencies, is it reasonable to assume that more ceiling treatments are necessary (in front of speakers, and in back row behind HVAC) in this circumstance?


My room is a bit on the live side, with half carpeted, and half pergo flooring. Front and back row dedicated seating on a riser.


Here are some pictures of my room, to give a better idea of what's going on.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9060#post_22383440
> 
> 
> I have been considering replacing some of my first reflection point absorbers (2" OC 703, framed, GOM'd and attached directly to wall) with diffusors. My decay time is a bit short, I think, (200ms) and I think the room is a wee bit to dead. Other than what I just posted, is there any other measurement that I should do to move me ahead with this (or cause me to dismiss the idea)?
> 
> Jeff



Hi Jeff,


Your listening distance should really play the bigger part in this decision. If you are (or any seats are) close to the new diffusors, they won't work as well. The front walls are a great space for diffusion in a HT room, since its typically the farthest boundary from the LP. Do also note that diffusors do absorb sound as well - they aren't 100% reflective. I think it depends on how much surface area you're really talking about here and room position is very important.


Could you attach a drawing or sketch of the room, along with speaker position, listening positions, and your current trap locations? It would help greatly to assess the situation.


Also, you can run a sine sweep and check the ETC response (Envelope Time Curve) to see the length of the decay time in your room, as well as spot any problem reflections. ETC is helpful for placing diffusors also.


----------



## kertofer

So I have a 19' X 16' X 8' room and have, at this point, put 3 panels that are about 30" X48" at the first reflection points along either side wall and put super chunk bass traps in the front corners (I cannot put them in the back corner as well due to door and windows getting in the way) and am thinking of my front wall now. My thought for the front wall was to build a faux wall which will allow me to put 2" OC703 across the entire wall leaving a 2-4" gap behind it to absorb along the entire wall. I am also thinking of getting some diffusers for the back wall as it is about 6' behind the rear listening position.


Thoughts on this plan?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *eiger*  /t/255432/acoustical-treatments-master-thread/9060#post_22388204
> 
> 
> Hi Guys -
> 
> I have a dedicated room that I'm experiencing some minor problems with. It's been a long time since I've done a full sweep of the room using REW or any other type of real time anaylysis.
> 
> My room has transformed quite a bit over the last year. (Riser was installed, new speakers, new amp, new pre-amp). So lots of new gear.
> 
> The room is 26 x 16 x 8. (3300cu ft) It is dedicated with 8 GIK 242s. No Corner Bass Traps. Three panels on each side wall, as well as behind each speaker. One on the ceiling. The problem seems to be emphais on the higher end of the frequency septrum.
> 
> What can I do to address this? Because I'm noticing it on the higher frequencies, is it reasonable to assume that more ceiling treatments are necessary (in front of speakers, and in back row behind HVAC) in this circumstance?
> 
> My room is a bit on the live side, with half carpeted, and half pergo flooring. Front and back row dedicated seating on a riser.
> 
> Here are some pictures of my room, to give a better idea of what's going on.



Hi Eiger,


Nice looking room! From a first glance it looks like your trap you have installed on the ceiling is too close to the speakers to grab your first reflection from the mains. Did you place it by measuring, or just visually? You might also need a panel behind that (closer to the LP) as well for killing the first reflection that would play back at the second row. Other than that though, if your room is still feeling a little live for you, yes - what you suggested would be a good route. I would also suggest perhaps trying some corner traps as well - they can surprisingly work very well for controlling flutter echo and other high frequency reflections, especially in the rear corners (usually where the speakers are aimed towards). And of course, they will do much better at absorbing bass when in the corners vs. flat against the wall, so you should be able to get some really great results back there in your situation.


Since you are a customer of ours, I'd welcome you to contact us anytime over the phone or through e-mail. We'd be happy to give you any suggestions and work with you and your room. http://gikacoustics.com/contact_us.html


----------



## GIK Acoustics




> Quote:
> Originally Posted by *kertofer*  /t/255432/acoustical-treatments-master-thread/9090#post_22390754
> 
> 
> So I have a 19' X 16' X 8' room and have, at this point, put 3 panels that are about 30" X48" at the first reflection points along either side wall and put super chunk bass traps in the front corners (I cannot put them in the back corner as well due to door and windows getting in the way) and am thinking of my front wall now. My thought for the front wall was to build a faux wall which will allow me to put 2" OC703 across the entire wall leaving a 2-4" gap behind it to absorb along the entire wall. I am also thinking of getting some diffusers for the back wall as it is about 6' behind the rear listening position.
> 
> Thoughts on this plan?



It would be more sensible to use lighter insulation in a 6" cavity for the front wall. Roxul Safe 'n Sound ( http://www.lowes.com/pd_89017-1278-RXSS323_0__?productId=3285120&Ntt=stone+wool+insulation ) works well at this depth for a cost efficient solution. I would also recommend putting a panel or two up at your first reflection points on the ceiling - that is equally important as the sidewalls! Also, if you did want to trap some more corners - don't forget there are 12 corners in a room, not 4. So, if you wanted addition corner coverage you could perhaps hit the back wall & ceiling corner with a superchunk, or just a straddled panel even.


Diffusors are excellent in home theaters. I would think you should be fine with a 6' distance (probably about 9' distance from the first row LP?).


----------



## kertofer

Cool, thanks a lot for the advice! I will do a little more measuring and see how big of a deal it would be to put 6" of insulation behind my screen.


As far as diffusers go, are there any good DIY diffusers or are those more custom and need to be ordered? I know that the old bookshelf of knick knacks trick is frowned upon, and for good reason, just not sure about the DIY market in general.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *kertofer*  /t/255432/acoustical-treatments-master-thread/9090#post_22391291
> 
> 
> Cool, thanks a lot for the advice! I will do a little more measuring and see how big of a deal it would be to put 6" of insulation behind my screen.
> 
> As far as diffusers go, are there any good DIY diffusers or are those more custom and need to be ordered? I know that the old bookshelf of knick knacks trick is frowned upon, and for good reason, just not sure about the DIY market in general.



You can download the program QRDude and play around for awhile till you get something that looks good, but getting something really great modeled in Reflex or other modeling programs for diffusion takes really long times to render (can be days or more), plus then you have to take the time to as diffusors can take a few days to cut, sand, glue, set, stain, dry, etc. Diffusors are not nearly as easy to DIY as absorption panels - however, if you have the time and skill to do it, it is definitely possible.


What I always say to people is the reason why people choose to buy commercial is because you are (usually) _guaranteed_ certain results. For example - yes you can build absorbers using practically any absorbent at any depth and get some results. However, if you buy our traps or other pro commercial solutions; we have paid thousands of dollars for real tests performed in laboratories by scientists - so you have ACTUAL absorption coefficients of the finished panels - we ensure easy mounting - we ensure great looking panels - money back guarantee - room setup advice and placement advice for your traps, the list goes on. So, it really depends on what you're able to do and what you have the time for I would say.


Proper diffusion construction does require some reading though..I would recommend Acoustic Absorbers and Diffusers: Theory, Design, and Application by Trevor Cox and Peter D. Antonio if you wanted to properly build one designed for your room and the exact environment it's placed in. I'm trying not to say that you either should 'buy a commercial diffusor' or 'you need to be a brain surgeon to build one', but its one of those scenarios where if you're going to build it, you might as well do it precise and correct so you don't end up needing to fix it later on.


----------



## pepar

Thanks Alex,


The room is nominal 21' long, 13' wide and 8' high. The rear (and main) row of seats is 72" from the rear wall. There is a false/screen wall with the LCR mounted behind it and directly to the front wall. Screen wall cavity is lined with 2" J-M Linacoustic, and there are 24" face SSC bass traps floor-to-ceiling in corners and wall-to-wall at wall/ceiling "corner.". Walls are carpeted up to seated ear level, a move that I would not repeat if I had to do it over.


I am trying to get my butt into the room with REW, but politics has me glued to the boob tube.


Jeff


----------



## Anhydro

*Does anyone know how using an upholstery GOM fabric on a bass trap will affect performance?* I'm having problems color matching the GOM acoustical fabrics. Thanks!


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9090#post_22392474
> 
> *Does anyone know how using an upholstery GOM fabric on a bass trap will affect performance?* I'm having problems color matching the GOM acoustical fabrics. Thanks!



If you want it to specifically be a bass trap, its fine; if you want it to also provide broadband absorption (not reflect high frequences), then wouldn't be a good choice.


----------



## Anhydro

Okay, one more goofy question... can I apply spray paint directly to linacoustic, which will go around the soffits, without affecting performance? I will be using this type of material on the screen wall as well, but will be placing Royal Velvet 3 over this... so, I thought that painting directly on linacoustic wouldn't afffect peformance. The coated side of the linacoustic would be facing out. Thanks.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9090#post_22392299
> 
> 
> Thanks Alex,
> 
> The room is nominal 21' long, 13' wide and 8' high. The rear (and main) row of seats is 72" from the rear wall. There is a false/screen wall with the LCR mounted behind it and directly to the front wall. Screen wall cavity is lined with 2" J-M Linacoustic, and there are 24" face SSC bass traps floor-to-ceiling in corners and wall-to-wall at wall/ceiling "corner.". Walls are carpeted up to seated ear level, a move that I would not repeat if I had to do it over.
> 
> I am trying to get my butt into the room with REW, but politics has me glued to the boob tube.
> 
> Jeff



Hi Jeff,


You do have a good amount of space for diffusion in the room. Your distance from the rear wall should be great. You do have some adequate treatment in there already (in terms of broadband absorption) - good work! Diffusion should help smooth out the reflections in your room, giving you a more balanced sound while still maintaining the liveliness the room currently has. If it were of concern, you could always place some diffusion in front of the carpet on the walls to send back some reflections instead of absorbing them. You could use commercial solutions or possibly look into using wooden slats in a simple diffuse pattern (such as Newell's sequence) to return some diffuse liveliness into the room. Newell's sequence gives a final ratio of 1:1 - that is 50% reflected, 50% open (to the absorptive carpet behind)


Here's a video we did on REW in case you haven't used it a lot: http://www.gikacoustics.com/video_rew_room_eq_wizard_tutorial.html 


There isn't much in the video on ETC measurements, but you take the measurements the same way.


> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9090#post_22392474
> 
> *Does anyone know how using an upholstery GOM fabric on a bass trap will affect performance?* I'm having problems color matching the GOM acoustical fabrics. Thanks!



You do know there are 48 colors available for GOM-FR701 correct? Otherwise, using upholstery fabric will probably work fine, though it is hard to predict how much of a difference the fabric will make without testing. It will affect performance, but to what degree is pretty much unknown. Might be a lot, might be small, might be unnoticeable.


> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9090#post_22394675
> 
> 
> Okay, one more goofy question... can I apply spray paint directly to linacoustic, which will go around the soffits, without affecting performance? I will be using this type of material on the screen wall as well, but will be placing Royal Velvet 3 over this... so, I thought that painting directly on linacoustic wouldn't afffect peformance. The coated side of the linacoustic would be facing out. Thanks.



The problem with the two quotes above is it is hard to say whether it will be harmful or not. Chances are, to long bass waves, neither will be detrimental. However, considering it is almost impossible to tell without actual testing (in other words, hard to predict) it is hard to say an answer as fact. I do not think, though, that it should make a large difference on the lower end or even the mids. I would suggest covering the JM Linacoustic RC with fabric though, not simply just placing them in and painting them if that is what you are suggesting.


----------



## Anhydro




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9090#post_22394730
> 
> 
> You do know there are 48 colors available for GOM-FR701 correct? Otherwise, using upholstery fabric will probably work fine, though it is hard to predict how much of a difference the fabric will make without testing. It will affect performance, but to what degree is pretty much unknown. Might be a lot, might be small, might be unnoticeable.
> 
> The problem with the two quotes above is it is hard to say whether it will be harmful or not. Chances are, to long bass waves, neither will be detrimental. However, considering it is almost impossible to tell without actual testing (in other words, hard to predict) it is hard to say an answer as fact. I do not think, though, that it should make a large difference on the lower end or even the mids. I would suggest covering the JM Linacoustic RC with fabric though, not simply just placing them in and painting them if that is what you are suggesting.



Thanks GIK! I've actually looked at all the acousitc fabrics (not just the FR701... way more than 48







), but my other decision input is an interior designer... so, I'm trying my best to compromise where I can. Based on what you've noted, I plan to use acoustic fabric with the Linacoustic and, unless I can find a coordinating acoustic fabric, I will go with the upholstery fabric on the bass traps. All the swatches are due to arrive tomorrow, so I'm still hoping we can find an acoustic fabric for everything.


----------



## pepar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9090#post_22394730
> 
> 
> Hi Jeff,
> 
> You do have a good amount of space for diffusion in the room. Your distance from the rear wall should be great. You do have some adequate treatment in there already (in terms of broadband absorption) - good work! Diffusion should help smooth out the reflections in your room, giving you a more balanced sound while still maintaining the liveliness the room currently has. If it were of concern, you could always place some diffusion in front of the carpet on the walls to send back some reflections instead of absorbing them. You could use commercial solutions or possibly look into using wooden slats in a simple diffuse pattern (such as Newell's sequence) to return some diffuse liveliness into the room. Newell's sequence gives a final ratio of 1:1 - that is 50% reflected, 50% open (to the absorptive carpet behind)
> 
> Here's a video we did on REW in case you haven't used it a lot: http://www.gikacoustics.com/video_rew_room_eq_wizard_tutorial.html
> 
> There isn't much in the video on ETC measurements, but you take the measurements the same way.



Wowy zowy!! Thank you. merci, gracias, danka! I watched part of it, bookmarked it and downloaded it (in Hi-Def) from Youtube. If you don't mind, I will be posting the Youtube link in other forums as REW comes up.


Jeff


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Anhydro*  /t/255432/acoustical-treatments-master-thread/9090#post_22395204
> 
> 
> Thanks GIK! I've actually looked at all the acousitc fabrics (not just the FR701... way more than 48
> 
> 
> 
> 
> 
> 
> 
> ), but my other decision input is an interior designer... so, I'm trying my best to compromise where I can. Based on what you've noted, I plan to use acoustic fabric with the Linacoustic and, unless I can find a coordinating acoustic fabric, I will go with the upholstery fabric on the bass traps. All the swatches are due to arrive tomorrow, so I'm still hoping we can find an acoustic fabric for everything.



If they are going to be just for treating mostly bass frequencies, I wouldn't get my hair in a knot about it. Again, its hard to predict the results but it isn't like you're putting a concrete barrier in front of the panels either.


> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9090#post_22395422
> 
> 
> Wowy zowy!! Thank you. merci, gracias, danka! I watched part of it, bookmarked it and downloaded it (in Hi-Def) from Youtube. If you don't mind, I will be posting the Youtube link in other forums as REW comes up.
> 
> Jeff



Thanks Jeff - glad you enjoyed the videos! Please do forward it out as you see fit. They are there for that exact reason - to help people out!


----------



## Digital_Chris

Just a quick question for you guys, as long as I can ask it in a way you understand...


I just finished watching "Sherlock Holmes - A Game Of Shadows" last night and found that even at a nice overall volume, the dialog was very, I don't know, harsh? I say harsh because the mid/low frequencies coming from the center seemed to be amplified almost and therefor a bit bothersome. It wasn't harsh in the high pitch/crackly way, but harsh in the mid frequencies. Dialog was clear and sounded good except for the end of most words were "boomy" almost, I don't know how else to describe it. Almost like if you say "hum", the "m" sound is aplified. I may sound foolish right now, I apologize 


If you have any idea on what I'm talking about, let me know what you think. I'm guessing it's from lack of wall treatment and will do some ETC testing soon but I wanted to hear your thouhgts on it in the mean time


----------



## kromkamp

"boomy voices" has for me always been the most prominent symptom of a room requiring acoustic treatment. Followed closely behind by a dialog track that seems alternately too quiet or too loud.


As an aside, I just saw the new Wachowski film "Cloud Atlas" at the Toronto film festival this past weekend. It was playing at a venue that usually houses live theater - not a movie theater. The acoustics were horrible in exactly this same way - voices so boomy it was hard to understand what they were saying!


----------



## stevegravley


I have a question about a certain type of symptom.  I was listening to my system yesterday at louder volumes than I could take for any extended period of time (just above reference).  I was doing this to test my sub, but it noticed something on my mid-high CHT's.  There were point at which the sound became glaring.  Almost like it was washing itself out, very harsh almost screeching; kind of like a locker room full of loud kids.

 

My setup is not done yet, but I do have treatments on my screen wall up (37" traps and front wall 2" 3pfc coverage).  My suspicion is that this is due to reflections in the room, but I wanted to make sure this is consistent with what you guys say.  I'll be adding wall treatments later down the road and am hoping this takes care of this problem.

 

While I watch movies, though, usually at just below reference, the effect is not very noticeable.


----------



## pepar




> Quote:
> Originally Posted by *stevegravley*  /t/255432/acoustical-treatments-master-thread/9090#post_22413241
> 
> 
> I have a question about a certain type of symptom.  I was listening to my system yesterday at louder volumes than I could take for any extended period of time (just above reference).  I was doing this to test my sub, but it noticed something on my mid-high CHT's.  There were point at which the sound became glaring.  Almost like it was washing itself out, very harsh almost screeching; kind of like a locker room full of loud kids.
> 
> 
> My setup is not done yet, but I do have treatments on my screen wall up (37" traps and front wall 2" 3pfc coverage).  My suspicion is that this is due to reflections in the room, but I wanted to make sure this is consistent with what you guys say.  I'll be adding wall treatments later down the road and am hoping this takes care of this problem.
> 
> 
> While I watch movies, though, usually at just below reference, the effect is not very noticeable.



"usually at just below reference, the effect is not very noticeable."


"listening to my system yesterday at louder volumes than I could take for any extended period of time (just above reference). ... it was washing itself out, very harsh almost screeching; kind of like a locker room full of loud kids."


Maybe you're hearing your spkrs distort? At normal listening levels is your dialog clear from shouting down to a whisper?


Jeff


----------



## stevegravley




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9090#post_22413317
> 
> 
> 
> At normal listening levels is your dialog clear from shouting down to a whisper?
> 
> Jeff


I'd have to say yes, very clear.  I never have an issue hearing dialog like I do upstairs in my non-treated vaulted living room.

 

Now that I think about it more, the effect did seem to increase and decrease some as I walked around the room.  This could be just me imagining the difference though.  I'm not sure.


----------



## Digital_Chris




> Quote:
> Originally Posted by *kromkamp*  /t/255432/acoustical-treatments-master-thread/9090#post_22412568
> 
> 
> "boomy voices" has for me always been the most prominent symptom of a room requiring acoustic treatment. Followed closely behind by a dialog track that seems alternately too quiet or too loud.
> 
> As an aside, I just saw the new Wachowski film "Cloud Atlas" at the Toronto film festival this past weekend. It was playing at a venue that usually houses live theater - not a movie theater. The acoustics were horrible in exactly this same way - voices so boomy it was hard to understand what they were saying!



They were a bit on the loud side as well, now that you mention it, moreso in the front row than in the back. Hopefully it's from lack of wall treatment. Man, now that I think of it, the front row is "worse" than the back row in multiple ways... boomy/louder dialog, lack of surround immersion and lack of bass... dang, I have some work ahead of me :-/


----------



## GIK Acoustics

Hello guys,


In Home Theater rooms you don't hear people complaining too much about muddy bass, since the LFE tracks are usually sparse during most movies - and no one really complains when an explosion was too boomy! However, dialog can be the most tell-tale sign of not enough bass trapping. From a lot of the builds, it seems many use relatively thin treatments - 1" to 2" rigid boards like OC703 or semi-rigid boards like Linacoustic RC, or even mineral wool. Don't get me wrong - a lot of this treatment certainly does the room good. However, in a lot of cases thicker treatments will help to better situate the overall levels in all aspects of the sound you're getting - from bass ranges all the way up into treble.


Chris, your description was spot on. Totally get what you are saying. That is likely due to room resonances. Instead of just seeing something louder on a frequency response curve, you can look at a waterfall graph to show the frequency response in relation to the time domain. In other words - certain notes will actually "ring" out longer than they are played. You may play a sound for 30ms but still hear it for 500ms. Bass trapping in important places like the back wall and corners of the room can certainly help to reduce that ringing significantly, giving you a much clearer sound. This is also why sometimes you will see not much of a change in frequency response with certain treatments, but hear an immense difference.


Steve, your description is a little bit harder to discern what the problem was. If it wasn't the speakers being pushed too hard, the problem could be a multiple of issues but it is odd that the problem doesn't persist at smaller volume levels, as most acoustic problems are room dependent, not speaker dependent. Could you listen again and report with a little more info on the issue at hand?


----------



## Dennis Erskine

If you're putting up a bunch of 1", 2", 4" fuzzy stuff (fiberglass board, cotton, mineral wool, whatever) in your room, you will change the sound. The problem is just using fuzzy stuff like that will frequently result in as big a problem as you had before you installed the fuzz.


----------



## myfipie




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9090#post_22414971
> 
> 
> If you're putting up a bunch of 1", 2", 4" fuzzy stuff (fiberglass board, cotton, mineral wool, whatever) in your room, you will change the sound. The problem is just using fuzzy stuff like that will frequently result in as big a problem as you had before you installed the fuzz.



Using proper broad band bass trapping can show a great deal of improvement which has been shown in thousands of rooms round the world. You can also take things further by using targeted trapping like pressure based membrane (tuned) trapping to further low end control. I also use another type of trapping called FRL (Frequency range limiter) that uses both concepts of broad band and tuned. Here is one test I did with just broad band and tuned which shows the effects. I do agree though that just throwing up a bunch of thin "fuzzy stuff" though might not give you the results you wanted.








http://www.gearslutz.com/board/7597560-post146.html


----------



## Irv Kelman




> Quote:
> Originally Posted by *stevegravley*  /t/255432/acoustical-treatments-master-thread/9090#post_22413337
> 
> 
> I'd have to say yes, very clear.  I never have an issue hearing dialog like I do upstairs in my non-treated vaulted living room.
> 
> 
> Now that I think about it more, the effect did seem to increase and decrease some as I walked around the room.  This could be just me imagining the difference though.  I'm not sure.



Proper sub and seat placement will help improve room interaction with your speakers for now.. Proper acoustic treatment later will make it even better.


----------



## Skylinestar

    


Attached here are the left, center, right view of my living hall. Width is about 15 feet. It's concrete construction all around.

The left wall has a big glass window, but it's always closed and the curtains pulled. The right wall is plain with a painting.

Please ignore the DSX front wide speakers as they are no longer there. 2 extra couches are replacing the position of these speakers.


Since everyone has told me that it's an overly live room (due to the construction), I'm about to put on some sound absorbers (DIY made from Roxul). I'll start with 2 panels...so I need to put them where it's most effective first...so where should I place them?


I assume the 2 panels should be hanged on the right wall (left and right of the painting) to combat first reflection. If I were to do that, is it possible that the right wall will be too much absorption and the left wall being too little? I assume that the left wall will have very little absorption because there's a big window with curtains, while the right wall is solid concrete, thus a perfect place for absorbers to achieve symmetry. But how is the reflectivity of glass vs concrete? Is it OK to hang these panels at same level with the painting? Or it must be same level with the front main speaker?


----------



## GIK Acoustics

Your first reflections are mostly obscured by furniture since the mains are so low in height. So, first sidewall reflections will likely not be most effective if you will only have 2 panels. On top of your concrete walls (which would make certain acoustic problems worse) you also have hard flooring which will make for even more reflections than a standard room. The window will likely be as live as the other walls in the room, though the curtains will (somewhat) absorb a little bit of sound.


However, first reflections don't make a room sound "live" - any significant amount of reflections do - whether they are the first reflections or not. Honestly, 2 absorbers is not much at all, especially in a room that size but you will definitely hear a difference. I would recommend adding some panels to the ceiling, sidewalls, and front or back wall. If your only goal is to deaden the room a bit on higher frequencies, 2" thick absorbers will do a good job. But if you want to evenly absorb down to lower frequencies, you will need to make larger 4" - 8" thick panels. Straddling corners with panels will give the panels a boost to absorb more lows than they would flat on the wall.


There is a lot of information you might find handy in our Acoustics Primer. You can check it out here: http://www.gikacoustics.com/education.html 

Though a lot of it relates to studios - the principals of room acoustics are the same regardless.


----------



## Skylinestar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9090#post_22476563
> 
> 
> Your first reflections are mostly obscured by furniture since the mains are so low in height. So, first sidewall reflections will likely not be most effective if you will only have 2 panels. On top of your concrete walls (which would make certain acoustic problems worse) you also have hard flooring which will make for even more reflections than a standard room. The window will likely be as live as the other walls in the room, though the curtains will (somewhat) absorb a little bit of sound.
> 
> However, first reflections don't make a room sound "live" - any significant amount of reflections do - whether they are the first reflections or not. Honestly, 2 absorbers is not much at all, especially in a room that size but you will definitely hear a difference. I would recommend adding some panels to the ceiling, sidewalls, and front or back wall. If your only goal is to deaden the room a bit on higher frequencies, 2" thick absorbers will do a good job. But if you want to evenly absorb down to lower frequencies, you will need to make larger 4" - 8" thick panels. Straddling corners with panels will give the panels a boost to absorb more lows than they would flat on the wall.
> 
> There is a lot of information you might find handy in our Acoustics Primer. You can check it out here: http://www.gikacoustics.com/education.html
> 
> Though a lot of it relates to studios - the principals of room acoustics are the same regardless.


I'll start with 2 panels as absorbers because the other Roxul batts will be built into basstraps. I'll definitely build more absorber panels.


I planning for this:the absorber treatment will be on the right wall (2 panels on left and right of painting) & front wall (probably 4 panels). The left wall with the big window and curtain will not be messed with (need to maintain WAF too). I hope this is correct.


----------



## GIK Acoustics

That does sound like a good plan, but I would recommend getting some for the wall with the window too. If you've got panels on the left wall, but none on the right, you'll definitely hear a difference between your right and left ear, which wouldn't be particularly comfortable sounding. You can always build some stands for them so they can match the height and placement of the ones on the right.


----------



## e2g_

So I skimmed through the first few pages some more, and perhaps I need to read a lot more but seeing that my questions may be specific to only me, I only got a few answers. I would appreciate if anyone can help me out with my questions, and provide any advice.


First, the setup up:
front_room_equipment1.jpg 82k .jpg file I have attached the following picture of downstairs where I have everything set up. The subwoofer is actually on the opposite side in between the tv and the left speaker. The couch is against the wall, and behind that wall is the stairs leading upstairs. We no longer have the dining table. Just two bikes. Also, the double window at the bottom of the sketch has a curtain.



What I understand is that
I need broadband bass traps at least 8" or more behind the head. 8" is probably pushing it and it may have to be the max
I need to bass trap as much as possible. Unfortunately, I will be limited to one corner (bottom right of sketch) due to the WAF, and this being a common room.
.....



Some of my questions apart from what should I do to help some of the acoustics in the room without breaking the bank (I am planning on building something since buying online seems out of my budget right now)


1. We have two cats. I am afraid that if they were to scratch the panel (especially the corner bass trap)..and get at the insulation, that may not be good. Are there any alternatives...or I shouldn't be worrying about this?

2. Being that the listening space is at one end of this rectangular shaped room downstairs, do you think 1st reflection points coming from the left side of the room (the side where the left speaker is located) is going to be a problem. I figured since those surfaces are further away, it would not be an issue. If it is, it may be an issue treating due to the lack of complete wall space.

3. For the broadband bass traps directly behind the head...and up to the ceiling, are these suppose to be 8" thick, and have no air gap?

4. I was planning on looking at some fabric from spoonflower (website) since there is a thread on here talking about how to make custom acoustic panels. Do people generally buy from a fabric store. This would be nice if I can do that, and allow my girlfriend to help pick something out with me but everything I see indicates that if you can blow through it, it is good enough. Is it really?

5. What exactly is straddling...straddling the wall?

6. I am willing to purchase a calibrated mic (parts express?) in order to figure out what I need to be addressing as I am not sure what I am bothered with. The room as some serious echo going on...and is quite evident when clapping in the room. That ringing I would like to control.....since those Klipsch horns can probably exaggerate that a lot.

IMG_3248.JPG 2254k .JPG file
IMG_3250.JPG 1710k .JPG file
jpg_low.jpg 2539k .jpg file
jpg2_low.jpg 1582k .jpg file


Thanks for your help and if this is the wrong thread, I do apologize.


I bookmarked this long time ago: http://www.avsforum.com/t/1295338/best-material-for-acoustic-panels/30 but after rereading it, I am not sure what to think. One thing I am sure is I would like to address the behind my head issue (and probably two panels up front) before moving to a corner bass trap.


----------



## flyng_fool

Has anyone thought about using spandex instead of GOM fabric for panels? The thought hit me when I was reading about the DIY spandex screens. If its as acoustically transparent as they say it is, it might be a cheaper alternative to GOM.


----------



## pepar




> Quote:
> Originally Posted by *flyng_fool*  /t/255432/acoustical-treatments-master-thread/9090#post_22484421
> 
> 
> Has anyone thought about using spandex instead of GOM fabric for panels? The thought hit me when I was reading about the DIY spandex screens. If its as acoustically transparent *as they say it is*, it might be a cheaper alternative to GOM.



Who is "they?"


----------



## flyng_fool

The guys using it for their DIY AT screens.


----------



## pepar

They are projecting onto the spandex??? Kids these days.










Anyway, I'd want to see some tests or have an acoustician weigh in.


Jeff


----------



## Peter M




> Quote:
> Originally Posted by *flyng_fool*  /t/255432/acoustical-treatments-master-thread/9100_50#post_22484421
> 
> 
> Has anyone thought about using spandex instead of GOM fabric for panels? The thought hit me when I was reading about the DIY spandex screens. If its as acoustically transparent as they say it is, it might be a cheaper alternative to GOM.



IMHO there are many more interesting uses for Spandex !










Cheers,


----------



## flyng_fool

Anyone? Bueller? Bueller?


----------



## Brad Horstkotte

Assuming its acoustically transparent enough to use for an AT screen, it would work for absorption panel coverings. I wonder though if you'd be able to see the Fiberglas/framing through it, since it is very sheer.


----------



## flyng_fool

That's what I initially thought until I read a bit more. They are saying it seems to be a pretty tight weave and they can't see any moire effect at all. I may get a small sample and try it to see. Or you could paint the face of the OC703 lightly with black spray paint to help with the see through. With the elasticity and four way stretch I think it would be much easier to work with than GOM. Hmmmmm...... It's really got me thinking.


----------



## bass addict




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9120_80#post_22490352
> 
> 
> Assuming its acoustically transparent enough to use for an AT screen, it would work for absorption panel coverings. I wonder though if you'd be able to see the Fiberglas/framing through it, since it is very sheer.



Most guys are doubling the spandex up with either a white/white or white/gray for their screens.


Seeing as there is no back lighting I doubt you'd have a problem with anything showing through behind it.


----------



## Skylinestar

 Plaster ceiling 

With respect to the plaster ceiling construction, is it OK to fill in OC703 batts in the ceiling (sandwiched between the solid concrete ceiling and the suspended plaster board held by the aluminum furring channel)? When installed this way, will it help in improving bass decay time?


----------



## flyng_fool

As far as I know only treatments inside the room will have an effect on the decay time, and to have an effect on the lower octaves it needs to be rather thick. See the bass traps threads for more info.


----------



## Brad Horstkotte

Stick with regular fluffy insulation inside wall/ceiling cavities, and save the more expensive rigid insulation for broadband traps inside the room.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9120#post_22492061
> 
> 
> Stick with regular fluffy insulation inside wall/ceiling cavities, and save the more expensive rigid insulation for broadband traps inside the room.



+1


----------



## Skylinestar




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9120#post_22492061
> 
> 
> Stick with regular fluffy insulation inside wall/ceiling cavities, and save the more expensive rigid insulation for broadband traps inside the room.


But the cheap fluffy stuff are not dense enough & won't do much on lower frequency.


The question remains...will decay time be improved with batts in ceiling cavities? One guy says no. Any other comments?


----------



## Elill

In wall insulation is to stop the wall acting like a drum, it doesn't have any/much direct acoustic benefit.


----------



## design1stcode2nd




> Quote:
> Originally Posted by *Elill*  /t/255432/acoustical-treatments-master-thread/9120#post_22493768
> 
> 
> In wall insulation is to stop the wall acting like a drum, it doesn't have any/much direct acoustic benefit.



So should interior theater walls have regular insulation? Exterior walls of course need it but I hadn't planned on doing interior walls since I'm not doing DD/GG/Clips.


----------



## HopefulFred

Yes, all the walls benefit from insulation - you don't want any resonating air cavities adjacent to your playback space (unless of course, you've tuned them for a specific purpose).


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9120#post_22493754
> 
> 
> But the cheap fluffy stuff are not dense enough & won't do much on lower frequency.
> 
> The question remains...will decay time be improved with batts in ceiling cavities? One guy says no. Any other comments?



Cheap fluffy stuff is effective at low frequencies if thick enough, and 2" of OC70X won't effect much low frequencies either. For wall construction, use the fluffy stuff.


Any insulation in the walls will reduce decay times _only if_ the decay times were imparted by resonation inside the wall construction. If there wasn't any prior, then it will not add much of a benefit other than a higher STC rating, and well, the expected benefits of heating & cooling.


----------



## e2g_

Hello guys, I was hoping I would still get some feedback on this. I fixed the images so you won't have to click and download each one.




> Quote:
> Originally Posted by *e2g_*  /t/255432/acoustical-treatments-master-thread/9090#post_22482632
> 
> 
> So I skimmed through the first few pages some more, and perhaps I need to read a lot more but seeing that my questions may be specific to only me, I only got a few answers. I would appreciate if anyone can help me out with my questions, and provide any advice.
> 
> First, the setup up:
> 
> 
> 
> I have attached the following picture of downstairs where I have everything set up. The subwoofer is actually on the opposite side in between the tv and the left speaker. The couch is against the wall, and behind that wall is the stairs leading upstairs. We no longer have the dining table. Just two bikes. Also, the double window at the bottom of the sketch has a curtain.
> 
> What I understand is that
> I need broadband bass traps at least 8" or more behind the head. I am not sure if I can get a panel thicker than 4" because of my girlfriend
> I need to bass trap as much as possible. Unfortunately, I will be limited to one corner (bottom right of sketch) due to the WAF, and this being a common room.
> .....
> 
> Some of my questions apart from what should I do to help some of the acoustics in the room without breaking the bank (I am planning on building something since buying online seems out of my budget right now)
> 
> 1. We have two cats. I am afraid that if they were to scratch the panel (especially the corner bass trap)..and get at the insulation, that may not be good. Are there any alternatives...or I shouldn't be worrying about this?
> 
> 2. Being that the listening space is at one end of this rectangular shaped room downstairs, do you think 1st reflection points coming from the left side of the room (the side where the left speaker is located) is going to be a problem. I figured since those surfaces are further away, it would not be an issue. If it is, it may be an issue treating due to the lack of complete wall space.
> 
> 3. For the broadband bass traps directly behind the head...and up to the ceiling, are these suppose to be 8" thick, and have no air gap?
> 
> 4. I was planning on looking at some fabric from spoonflower (website) since there is a thread on here talking about how to make custom acoustic panels. Do people generally buy from a fabric store. This would be nice if I can do that, and allow my girlfriend to help pick something out with me but everything I see indicates that if you can blow through it, it is good enough. Is it really?
> 
> 5. What exactly is straddling...straddling the wall?
> 
> 6. I am willing to purchase a calibrated mic (parts express?) in order to figure out what I need to be addressing as I am not sure what I am bothered with. The room has some serious echo going on...and is quite evident when clapping in the room. I am not sure what else is wrong in particular, and would like to narrow it down
> 
> 
> 
> 
> 
> 
> 
> Thanks for your help and if this is the wrong thread, I do apologize.
> 
> I bookmarked this long time ago: http://www.avsforum.com/t/1295338/best-material-for-acoustic-panels/30 but after rereading it, I am not sure what to think. One thing I am sure is I would like to address the behind my head issue (and probably two panels up front) before moving to a corner bass trap.


----------



## mtbdudex

E2g


Do 1 thing at a time.


If I were you, I'd do in order.


Create a RFZ on sidewalls, use 4" 703 with 4" air gap if possible.

See how that improves your imaging and soundstage


Next:

Broadband bass traps, bigger is best, they will help reduce your bass decay to improve the bass PQ. As much coverage as you can, really big ones use pink fluffy. There are separate threads on why.


I'd stay away from backwall treatments for now, until you do the above, then get into the whole measurement thing.

Maybe you don't need back wall treatments.


Have fun, DIY will save some $ for you.



Sent from my iPhone4 using Tapatalk

[edit]

ok doing this on iPhone i could NOT see your living room layout.

You might want to consider moveable stand mounted side RFZ panels, possible wrapped in the spoonflower fabric for WAF/GF aesthetics.

Might even consider a ceiling cloud for the RFZ, 6" thick with 6" air gap.


----------



## e2g_

mtbdudex


Thanks for the suggestion. I am limited on the thickness for our space. So I will just play around with the max I can go, and see where it takes me from there.


----------



## mtbdudex

e2g;

Totally understand space limitations.

Since your area is non-symmetrical, LH open very much and RH has doorwall, you might consider an acoustic cloud to handle ceiling reflections......

You'd have to ditch the fan, and re-do your ceiling lights.....

http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames#post_19987247 
 


Again measurements do seem best in your case, ETC, depends on how serious you are to truly identification the WHAT to do, then tackle/improve your acoustics.

A good recent thread is here:
http://www.avsforum.com/t/1432713/using-waterfall-and-etc-graphs-to-analyze-room-response


----------



## e2g_

Quick question mtbdudex, well, more like a confirmation.


I haven't called any stores yet to see if they sell Owen Corning 703 and how much if they do but I came across this and it seems pretty cheap: Roxul Safe n Sound

http://www.lowes.com/ProductDisplay?langId=-1&storeId=10151&catalogId=10051&productId=3285120&cId= 


I really liked this guys design, and will end up going with something like this: http://hardforum.com/showpost.php?p=1036726646&postcount=18 . Seems like it lessens any reflections that can occur from the frame itself. So my question, since I have never came across this Roxul Safe and Sound, and seeing that OC 703 is obviously looks nice and rigid, would going with the rigid fiberglass be a better option if I want the front of the panel to be nice and squared/flat shape. Or will the Roxul provide enough rigidness to not look like I have a pillow hanging on the wall?



I think I will doing something like this for our front room (front wall behind the plasma). and trying to squeeze in as thick of a panel as I can around the front corner:

 



Thanks for the links!


EDIT:


According to this site - Link , it would be wise to use less dense material such as the safe n sound in the corners, but provided that I have the corners at least 6" or more deep. I am planning on covering most of the wall in the front but some of these tiles (according to that picture) will not have any insulation in them to not overdo the mids and the highs. I just want to be sure if I can stick to one type of insulation (preferably cheap), and double up on a single panel for added thickness (air gap too) if I get the opportunity all the while having something such that when I wrap with cloth, it doesn't look like a pillow but have a nice clean finish.


----------



## Holiday121

Anyone in the Ne Ohio area that could help with a treatment layout


----------



## GIK Acoustics




> Quote:
> Originally Posted by *e2g_*  /t/255432/acoustical-treatments-master-thread/9120#post_22524734
> 
> 
> Quick question mtbdudex, well, more like a confirmation.
> 
> I haven't called any stores yet to see if they sell Owen Corning 703 and how much if they do but I came across this and it seems pretty cheap: Roxul Safe n Sound
> http://www.lowes.com/ProductDisplay?langId=-1&storeId=10151&catalogId=10051&productId=3285120&cId=
> 
> I really liked this guys design, and will end up going with something like this: http://hardforum.com/showpost.php?p=1036726646&postcount=18 . Seems like it lessens any reflections that can occur from the frame itself. So my question, since I have never came across this Roxul Safe and Sound, and seeing that OC 703 is obviously looks nice and rigid, would going with the rigid fiberglass be a better option if I want the front of the panel to be nice and squared/flat shape. Or will the Roxul provide enough rigidness to not look like I have a pillow hanging on the wall?.



Roxul Safe'n'Sound is cheap and a good bet for acoustics, but just as you proposed is very floppy and needs a frame. It would look like a pillow as you suggest. It is very light and floppy.


----------



## Holiday121




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9120#post_22524974
> 
> 
> Roxul Safe'n'Sound is cheap and a good bet for acoustics, but just as you proposed is very floppy and needs a frame. It would look like a pillow as you suggest. It is very light and floppy.



I used Roxul inside of my main stage. Pretty easy to work with and cuts like butter.


----------



## NicksHitachi


Found this today for anyone pondering building a DIY QRD.

 

http://www.mh-audio.nl/diffusor.asp#calcul


----------



## e2g_




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9120#post_22524974
> 
> 
> Roxul Safe'n'Sound is cheap and a good bet for acoustics, but just as you proposed is very floppy and needs a frame. It would look like a pillow as you suggest. It is very light and floppy.



Thanks. I may have found one place that sells OC 703. It seems like Roxul/Rockwool Rockboard 60 is a good alternative as well but no one seems to carry it.


----------



## GrasaDeCastor

It was suggested that I post this in this wonderful thread that I did not know existed and given that you guys are obviously the ones to talk to about this, I suppose I need to give a little insight into my exact situation so you know what I'm asking to begin with.


Here are a couple of picture of my living room where I am setting this all up as well as an updated pic of the work I had to do to the mantle to get the new center channel speaker to fit. The mantle has since been completed and painted as of the time this pic was taken.


**Update** I've added a couple pics with the new speakers.

 
 
 
 
 
 
 
 


The speakers shown in these pictures, except for the last picture of the mantle, are focal's. (I've since added a couple new pics of the mounted bookcase speakers) They are bookshelf speakers that I recessed into the wall when we got the tv set up over the mantle thinking that was just awesome.







After having the Focal's for some time, it became more and more annoying that sometimes I would have a hard time making out voices, etc. and the 8in sub that came with the kit was a far cry from what I needed to fill that space so I thought that just getting bigger better speakers would do the trick.


Anyway, these focals are gone now, the holes are patched up and in their place, on Omnimount 60.0 brackets, are Paradigm Studio 20 bookshelf speakers, a cc-590 center on the mantle, and ADP-590 surrounds, which are actually coming in the mail today and I have not fully decided how to mount just yet. The ADP's however, will not be mounted on the wall behind the couch, on either side of the window like the focal's are now. They will most likely go on side walls, to the left and right of the couch. I was thinking of putting a couple of acoustic panels on either side of the window where the focals currently reside. The Studio 20's are pointed slighty in from an apporximate 30 degree angle and the cc-590 center as well as the Studio 20's are all pointed slightly down into the listening position. The center channel, as you can see, has to no choice but to be butted up against the stone, as there is just no other place to put it. It is rear ported and I've plugged the port with styrofoam and the sound seems to be quite good out of it. I can not hear any chuffing or boomy muddy bass/sound from it. Would it be of benefit to put some Roxul insulation behind it?


Also, I have replaced the 8" sub with the Premier Acoustics PA-150 15" subwoofer. I have an Onkyo tx-sr507 (which can be seen in the right side of the third picture) with Audyssey which I have learned is much better at setting up the speakers the way they should be than I am. So I've run Audyssey, it has the speakers crossing over at 70, etc., and I've set the subwoofer accordingly and have not touched the settings there after. The sub is sitting in between the big fluffy chair and the end table, basically under the receiver that is mounted to the wall behind the fluffy chair. It is a couple of feet away from the wall and pointed straight out into the room.


So here is the problem. With Audyssey set up, speakers set up to the best of my limited acoustic ability, when I put a movie in and watch it for a while, (LOTR, or Master and Commander, any good surround sound movie) it initially seems to sound awesome, but I still feel like I should be able to hear the voices clearer and as if that wasn't annoying enough, after a short bit, I notice that my ears are actually starting to hurt which makes no sense to me because I am not playing it louder than when I go into a movie theater and my ears aren't hurting when I'm done watching a movie in a theater. This led me to search google and I find a thing called "listening fatigue" and it seems to be from horrible acoustics more than anything which seems to go along with the fact that I have "clap echo". I know its not the Paradigms because I auditioned them for quite a while and bought them specifically because they were so much easier to listen to than the Klipsh's which I did noticed were hard on my ears.


So that is where I am at, and is why I am looking at making some acoustic panels, most probably from the 3 1/2 in Roxul from lowes that is routinely recommended. I was thinking of putting a couple acoustic panels above the love seat at the first reflection, and maybe a couple more on the slanted ceiling above the couch at reflection points there, and was considering putting them higher up on the walls, above all the pictures to help deaden the sound echoing out of the cathedral ceiling. Also a couple on either side of the picture window. I am also toying with the idea of an acoustic "cloud". Just saw some plans for a couple today. We have some nice thick black-out blinds that I can draw down in front of the window, as well as the curtains to help keep noise from bouncing off the glass. For a reference of scale on how large the room is, the tv is 65". Also, with the bookshelf speakers on the Omnimounts, they are only about 8" away from the wall so should I put an acoustic panel directly behind them as well?


Any insight into how to better this situation is greatly appreciated.

Thanks for all the great input so far!!


----------



## mtbdudex

Wow, good luck, GrasaDeCastor.

Tackling acoustics in a general/open living room is so much more challenging than a dedicated Home Theater.


Is changing your room layout an option?

Such as moving your set-up 90 degrees, putting your front soundstage speakers at ear height, your rear surrounds on speaker stands?

Then doing a basic sub crawl for optimal sub location.


Then run audyssey and see how it sounds.

Then, you could consider some movable side acoustic panels for 1st reflection absorption as initial step.
 


Possible some corner broadband bass traps, but that's later down the road.

I'm surprised Audyssey does not dial down your over bright/reflective sound with its eq at least somewhat even now as your set-up is.


Just throwing that out there.......


----------



## Holiday121

Looking for some help to start in my room . Was thinking of making some panels or bass traps do my room. Which would you start with?


And if bass traps would you do the front two corners first or the back two?


I have been reading many threads on how to build. It's all starting to confuse me . Any certain measures I should keep on track with or any link that I should stick to for the build?



It will be going in a 7.2 or 7.3 theater room used or mostly movies an gaming.


----------



## pepar

All modes are active in tri-corners. Start there. Wall-wall is a corner. Wall-floor is a corner. Wall-ceiling is a corner. Wall-wall-ceiling is a tri-corner. Wall-wall-floor is a tri-corner. Beyond tri-corners, which are "bonus" corners, a corner is a corner is a corner.


If you have measurement software, use that to find your most active/troublesome modes, and that will dictate more efficient placement, and alternative treatments. IOW, test, hypothesize/diagnose, treat, repeat.


In an otherwise empty/reflective room, studiotips superchunks and first reflection point absorbers are a good thing. In other rooms, your mileage will vary.


----------



## Holiday121




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9120#post_22543441
> 
> 
> All modes are active in tri-corners. Start there. Wall-wall is a corner. Wall-floor is a corner. Wall-ceiling is a corner. Wall-wall-ceiling is a tri-corner. Wall-wall-floor is a tri-corner. Beyond tri-corners, which are "bonus" corners, a corner is a corner is a corner.
> 
> If you have measurement software, use that to find your most active/troublesome modes, and that will dictate more efficient placement, and alternative treatments. IOW, test, hypothesize/diagnose, treat, repeat.
> 
> In an otherwise empty/reflective room, studiotips superchunks and first reflection point absorbers are a good thing. In other rooms, your mileage will vary.




Eh I did not understand any that I guess I'm in way over my head sorry


----------



## pepar




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9120#post_22543429
> 
> 
> Looking for some help to start in my room . *Was thinking of making some panels or bass traps do my room. Which would you start with?*
> 
> And if bass traps would you do the front two corners first or the back two?



Boiling it down ...


For bass traps it doesn't matter which corners you start in.


In an otherwise empty/reflective room, bass traps and first reflection point absorbers are a good thing.


Jeff


----------



## Holiday121




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9150#post_22543556
> 
> 
> Boiling it down ...
> 
> For bass traps it doesn't matter which corners you start in.
> 
> In an otherwise empty/reflective room, bass traps and first reflection point absorbers are a good thing.
> 
> Jeff



Ahh ok let me see what kind if Roxul I have leftover from my stage


----------



## GIK Acoustics




> Quote:
> Originally Posted by *GrasaDeCastor*  /t/255432/acoustical-treatments-master-thread/9120#post_22542148
> 
> 
> Any insight into how to better this situation is greatly appreciated.
> 
> Thanks for all the great input so far!!



GrasaDeCastor,


So it seems you have two problems:

1. Dialogue isn't as present as you would like.

2. Higher frequencies are causing ear fatigue.


The first problem is due to low frequency issues, usually around the 80-150 Hz range. I would make two suggestions to help clear this up:

Step one - Try to get the sub in the most optimal position. I would disconnect Audyssey, and put in a DVD or CD with dialogue that seems to be thin or not as present. Crawl your subwoofer around until you are able to get some more presence in dialogue. Reconnect Audyssey and have a listen from there. If you've already found the absolute optimal sub position, then just go on to the second step.

Step two - bass traps. For ranges of 80-150 Hz a few different types of absorbers work well. From the tests we have done on our 244, it has a great absorption coefficient at 80 Hz when straddling a corner, and it absorbs very well above that as well. Or, you could use some wall mounted panels, though they won't have as strong of a presence at 80 Hz (still very effective, though, for dialogue frequencies)


The second problem, as you suggested, is likely due to room acoustics. The particular phenomenon you described is actually known as "flutter echo". Luckily, it is one of the easiest problems to treat, as relatively thin treatment is usually substantial. Flutter echo happens between two parallel hard surfaces in the room. This means that while treating your ceiling will help with first reflections and reverb reduction, there shouldn't be much flutter echo between your ceiling and your floor since they are not parallel at all. Also, staggered treatment will be most effective at combating flutter echo. For example, if one wall was 100% treated with absorption, and the parallel wall to it was completely untreated, there would be no flutter echo. So, having treatment staggered (ie. parallel to a blank area on the wall) will result in more flutter echo reduction than if treatment was parallel with more treatment. However, this can skew stereo image - so I would recommend this on the ceiling, front, or back wall, but not the sidewalls.


Another phenomenon that can cause ear fatigue is simply loud early reflections. Early reflections are the first reflections that come from a boundary, typically right after the direct sound hits your ears. This can result in unpleasant sounds, and easily ear fatigue (as you will hear every loud transient multiple times, instead of once). Treating your first reflection points on the ceiling, as well as the sidewalls can help cut down these reflections to a much smaller level, allowing you to hear what comes out of the speakers, instead of what's bouncing off your walls. This is why something like Audyssey cannot correct all room problems, as no matter what comes out of the speakers, there will always be harmful reflections.


Considering treating your reflection points will already help combat some echo, I would recommend doing that first. If you wish to combine bass trapping with your flutter treatment, making or buying thicker absorbers (4" to 8" thick) will help treat both the low end and the high end. Perhaps a few panels on the ceiling, a few on the sidewalls, and some on the front or back wall should give you a very good start without breaking the bank. From there you can decide if your room needs more treatment, or if fits your needs and rids of the fatigue.


Please let me know if you have any questions!


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9120#post_22543429
> 
> 
> Looking for some help to start in my room . Was thinking of making some panels or bass traps do my room. Which would you start with?
> 
> And if bass traps would you do the front two corners first or the back two?
> 
> I have been reading many threads on how to build. It's all starting to confuse me . Any certain measures I should keep on track with or any link that I should stick to for the build?
> 
> It will be going in a 7.2 or 7.3 theater room used or mostly movies an gaming.



It would depend on the certain problems that are in the room, but as a general guide, starting with thicker porous absorption will help both the low frequencies and high frequencies, so I would start there. In most cases, getting the low end right will usually sort most problems in the higher frequencies. I would start in all four main corners if possible, and floor to ceiling again if possible. If you are only able to do one or the other to start with, try both positions. It certainly depends on speaker and sub placement, as well as the room, to suggest which corners will be most important. Could you give a layout of the room?


Edit: We also have a lot of information on room modes, and other issues in room acoustics on our website in our Education section, as well as our Videos section. You can check out our Acoustics Primer here: http://www.gikacoustics.com/education.html


----------



## GrasaDeCastor




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9150#post_22544700
> 
> 
> GrasaDeCastor,
> 
> So it seems you have two problems:
> 
> 1. Dialogue isn't as present as you would like.
> 
> 2. Higher frequencies are causing ear fatigue.
> 
> The first problem is due to low frequency issues, usually around the 80-150 Hz range. I would make two suggestions to help clear this up:
> 
> Step one - Try to get the sub in the most optimal position. I would disconnect Audyssey, and put in a DVD or CD with dialogue that seems to be thin or not as present. Crawl your subwoofer around until you are able to get some more presence in dialogue. Reconnect Audyssey and have a listen from there. If you've already found the absolute optimal sub position, then just go on to the second step.
> 
> Step two - bass traps. For ranges of 80-150 Hz a few different types of absorbers work well. From the tests we have done on our 244, it has a great absorption coefficient at 80 Hz when straddling a corner, and it absorbs very well above that as well. Or, you could use some wall mounted panels, though they won't have as strong of a presence at 80 Hz (still very effective, though, for dialogue frequencies)
> 
> The second problem, as you suggested, is likely due to room acoustics. The particular phenomenon you described is actually known as "flutter echo". Luckily, it is one of the easiest problems to treat, as relatively thin treatment is usually substantial. Flutter echo happens between two parallel hard surfaces in the room. This means that while treating your ceiling will help with first reflections and reverb reduction, there shouldn't be much flutter echo between your ceiling and your floor since they are not parallel at all. Also, staggered treatment will be most effective at combating flutter echo. For example, if one wall was 100% treated with absorption, and the parallel wall to it was completely untreated, there would be no flutter echo. So, having treatment staggered (ie. parallel to a blank area on the wall) will result in more flutter echo reduction than if treatment was parallel with more treatment. However, this can skew stereo image - so I would recommend this on the ceiling, front, or back wall, but not the sidewalls.
> 
> Another phenomenon that can cause ear fatigue is simply loud early reflections. Early reflections are the first reflections that come from a boundary, typically right after the direct sound hits your ears. This can result in unpleasant sounds, and easily ear fatigue (as you will hear every loud transient multiple times, instead of once). Treating your first reflection points on the ceiling, as well as the sidewalls can help cut down these reflections to a much smaller level, allowing you to hear what comes out of the speakers, instead of what's bouncing off your walls. This is why something like Audyssey cannot correct all room problems, as no matter what comes out of the speakers, there will always be harmful reflections.
> 
> Considering treating your reflection points will already help combat some echo, I would recommend doing that first. If you wish to combine bass trapping with your flutter treatment, making or buying thicker absorbers (4" to 8" thick) will help treat both the low end and the high end. Perhaps a few panels on the ceiling, a few on the sidewalls, and some on the front or back wall should give you a very good start without breaking the bank. From there you can decide if your room needs more treatment, or if fits your needs and rids of the fatigue.
> 
> Please let me know if you have any questions!



Alexander,


Thank you for taking the time to write that up! That is exactly the kind of information I was looking for. I made it over to your site that you linked in another post and it looks like next month when the budget permits I will be ordering some of the 242 acoustic panels. Your post and your site are both a fount of information and can't say enough how much I appreciate you breaking it down in layman's terms like that for me. I'll start with a few of the acoustic panels as you suggest, re-listen and see if I feel like it needs more treatment, possibly a couple of corner bass traps, and take it from there. In the mean time I've ordered a 30ft sub cable so I can play with that until I get some panels.


Thanks again!

GrasaDeCastor


----------



## Holiday121

So I decided to go with corner bass traps first making them 24 inches wide.


So after making them I plan on using the Roxul safe n sound bags I have left over. Do I just cut them into triangle pieces stack to the ceiling and cover with fabric?


----------



## pepar

 http://peparsplace.com/pg23.html


----------



## Brad Horstkotte

I stacked my triangles between 2x2s on each side, to keep them into place - 2x2s screwed and liquid nailed to the walls:











Then fabric can be stapled to the 2x2s.


----------



## mtbdudex

I'm sure Brad/Pepar/myself - among others - have posted this answer 4-5-6 times...Mo-ichi-do


Stack them low and high, with shelf top is possible, details in this link:
http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/30#post_20007037 





























also stacking floor/ceiling, this simple pict should help visualize different approach:










to give this:



















I'd like to add;

For big corner bass traps like these shown you can use HD/Lowes Pink fluffy instead of the more expensive/denser stuff I used - and get better performance, it's related to the gas flow resistivity....there are posts in this thread that explain it so I won't re-hash those here.


----------



## cuzed2




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9150#post_22551423



mtbdudex;

Any more details on how you shaped/constructed these bad-boys (the ones in the upper corners)?


----------



## Holiday121




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9150#post_22551423
> 
> 
> I'm sure Brad/Pepar/myself - among others - have posted this answer 4-5-6 times...Mo-ichi-do
> 
> Stack them low and high, with shelf top is possible, details in this link:
> http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/30#post_20007037
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> also stacking floor/ceiling, this simple pict should help visualize different approach:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> to give this:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'd like to add;
> 
> For big corner bass traps like these shown you can use HD/Lowes Pink fluffy instead of the more expensive/denser stuff I used - and get better performance, it's related to the gas flow resistivity....there are posts in this thread that explain it so I won't re-hash those here.



Any of the pink fluffy stuff or should I look for something specific.


Thanks for the help going to try to make a few this week.


----------



## mtbdudex




> Quote:
> Originally Posted by *cuzed2*  /t/255432/acoustical-treatments-master-thread/9150#post_22551524
> 
> 
> 
> 
> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9150#post_22551423
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> mtbdudex;
> 
> Any more details on how you shaped/constructed these bad-boys (the ones in the upper corners)?
Click to expand...


In my signature there is a link for my DIY acoustic treatments thread. I can't repost that from iPhone.


Have fun making yours



Sent from my 32GB iPhone4 using Tapatalk


----------



## cuzed2

Thanks! I'll take a closer look when I am on a real computer


----------



## Holiday121

So using something like this should be ok?

http://m.homedepot.com/p/Owens-Corning-EcoTouch-R-30-Unfaced-9-1-2-in-x-15-in-x-25-ft-Continuous-Roll-Insulation-RU70/202585906/


----------



## Brad Horstkotte

Yup


----------



## Holiday121

Wow that's cheap compared to the Roxul


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9150#post_22552601
> 
> 
> Wow that's cheap compared to the Roxul



Yes it certainly is! It will work great for very thick traps. Theoretically, the Roxul should be a small bit better until about 18" thick, where the pink fluffy will start to become a small bit better. The small advantage should not make much of a real world difference with 4 floor to ceiling traps though.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *GrasaDeCastor*  /t/255432/acoustical-treatments-master-thread/9150#post_22546593
> 
> 
> Alexander,
> 
> Thank you for taking the time to write that up! That is exactly the kind of information I was looking for. I made it over to your site that you linked in another post and it looks like next month when the budget permits I will be ordering some of the 242 acoustic panels. Your post and your site are both a fount of information and can't say enough how much I appreciate you breaking it down in layman's terms like that for me. I'll start with a few of the acoustic panels as you suggest, re-listen and see if I feel like it needs more treatment, possibly a couple of corner bass traps, and take it from there. In the mean time I've ordered a 30ft sub cable so I can play with that until I get some panels.
> 
> Thanks again!
> 
> GrasaDeCastor



Wonderful!


I would suggest the 244s instead of the 242s considering you have some problems in dialogue (and the price difference for doubling the thickness is pretty minuet)


Glad I was able to help.


----------



## Nightlord




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9150#post_22552601
> 
> 
> Wow that's cheap compared to the Roxul



Do check that the material/density is in a reasonable range. If it doesn't work as well, then it's not cheap - just inexpensive.


----------



## Holiday121




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9150#post_22552694
> 
> 
> Do check that the material/density is in a reasonable range. If it doesn't work as well, then it's not cheap - just inexpensive.



What do you mean exactly ?


----------



## Nightlord

Too high density and it will reflect too much, too little and it will absorb less.


Stonewool has to be 60-70% higher in density compared to glass wool for the same effect, also.


----------



## Holiday121




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9150#post_22552738
> 
> 
> Too high density and it will reflect too much, too little and it will absorb less.
> 
> Stonewool has to be 60-70% higher in density compared to glass wool for the same effect, also.



Did you see the link above? Is that ok to use in your opinion


----------



## mtbdudex

This thread on gearslutz is very good for materials-gas-flow-properties info
http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/177600-could-someone-help-out-interpreting-materials-gas-flow-properties.html 


Somewhere in all these 1,000's of posts localhost127 made a good visual to grasp that....


----------



## Nightlord




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9150#post_22552764
> 
> 
> Did you see the link above? Is that ok to use in your opinion



I'll leave that up to someone native to Imperial.


----------



## Holiday121

Ok I picked up a few rolls iof this today.

http://m.homedepot.com/p/Owens-Corning-EcoTouch-R-30-Unfaced-9-1-2-in-x-15-in-x-25-ft-Continuous-Roll-Insulation-RU70/202585906/ 


Just unroll them and cut into triangles? I was reading some people leavd plastic on. I am going from floor to ceiling so all atleast 86 inches plus in height.


Going to go with a 24 in front .


So if I do cut then into triangles should I compress them down or just lay on top?



Also I need to pick up some fabric from Joann fabrics tommorow. Anything in particular I should look for? From what I read that you should be able to blow through the material. Or does this not matter when it comes to corner bass traps


----------



## mtbdudex




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9150#post_22555174
> 
> 
> Ok I picked up a few rolls iof this today.
> 
> http://m.homedepot.com/p/Owens-Corning-EcoTouch-R-30-Unfaced-9-1-2-in-x-15-in-x-25-ft-Continuous-Roll-Insulation-RU70/202585906/
> 
> 
> Just unroll them and cut into triangles? I was reading some people leavd plastic on. I am going from floor to ceiling so all atleast 86 inches plus in height.
> 
> 
> Going to go with a 24 in front .
> 
> 
> So if I do cut then into triangles should I compress them down or just lay on top?
> 
> 
> 
> Also I need to pick up some fabric from Joann fabrics tommorow. Anything in particular I should look for? From what I read that you should be able to blow through the material. Or does this not matter when it comes to corner bass traps



Can you re-think and go with 34" front? What is limiting you to 24" front?

Bigger is better for broadband bass traps.


This will show you one pink fluffy build method, from http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/120#post_22131618 


> Quote:
> Originally Posted by *Eric2000*  /t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/120#post_22131618
> 
> 
> Hi guys,
> 
> 
> I've been following a number of the acoustics threads here for a while, though I haven't been very active on the AVS forums. Mike suggested that I share some of my work on room acoustics with everyone here, so here are my corner bass traps:
> 
> 
> I followed a similar construction technique that Mike posted for his corner bass traps, but made mine from pink fluffy R-19 instead and wrapped the fabric around the outside of the threaded rod. Here is the photo journey:
> 
> 
> My traps are 24x24x34 inch triangles, are about 3.5 feet tall, and probably weigh less than 10lbs each. Since I need access to one of the corners for a doorway, I made them stackable and moveable. I started by cutting triangles, drilling holes for the threaded rod, and inserting T-Nuts for the sides that stack on one another:
> 
> 
> 
> Then I cut 23" squares of insulation, cut them diagonally for triangles, and clipped off the corners so they fit snugly between the threaded rods:
> 
> 
> 
> 
> A wire mesh made from separated Cat5 wire goes between each layer to keep the insulation from sagging over time. The numbered arrows indicate the direction of winding the wire to support the insulation. A bead of solder keeps the wire from unwinding. Each layer of insulation is about 5" thick.
> 
> 
> 
> Here is the first one all stacked up. You can see the supportive wire mesh wrapped around the threaded rod on each side:
> 
> 
> 
> And then with the Kraft paper glued to the front with spray adhesive:
> 
> 
> 
> Then, turn the trap upside down to affix the cloth wrapping - a two-pack of curtains from the giant W for $15. Each pack is enough for two traps.
> 
> 
> 
> The cloth is stapled to the underside of the top plate to prevent sagging over time:
> 
> 
> 
> When the fabric is fully secured to the top panel, turn the trap right side up again and pull the fabric around to the back. Trim off the excess and then just pull it tight and use a desk stapler to hold the fabric together in the back:
> 
> 
> 
> The staples produce a few ripples in the sides, but you won't see those once you put it in the corner. The front looks nice and clean:
> 
> 
> 
> Here is a closer shot of two of them stacked together:
> 
> 
> 
> And finally, the entire back half of the theater. With a few bean bag chairs up front, we can comfortably seat 10-12 people. The colors are a little off from a combination of CFL and flash lighting:
> 
> 
> 
> Below are the before and after REW plots. The purple trace is the original measurement with no traps and no EQ. The yellow trace is the difference made by the bass traps alone. The traps took 5dB off of the room-induced peak at 45Hz without sacrificing anything else in the audible range:
> 
> 
> 
> This is the original waterfall plot made by REW - no traps, no other corrections - just a mess with room modes at 45Hz and 90Hz:
> 
> 
> 
> And here is the waterfall plot after ONLY the traps are put in place. I was surprised by how much of a difference the traps made in the decay:
> 
> 
> 
> After several days of tweaking the parametric equalizer with the traps in place and a first order high-pass filter in place, here is my "final" room response curve - flat from 7Hz to 100Hz, plus/minus 3dB :'( The peak at 105Hz won't ever really happen because the preamp crosses the LFE channel at 60Hz.
> 
> 
> 
> And the "final" waterfall plot - nice and smooth. If I adjust the waterfall graphing limits in REW, the entire response curve is down by 20dB within the first 100-120ms with the exception of a 2-3dB narrow bump at about 23Hz. I am really pleased with this result:
> 
> 
> 
> It sounds great! The EQ and high-pass filter reduce (but don't eliminate) the incidence of amp clipping, but still provide enough punch to cause visitors to literally jump up from the couch
> 
> 
> All of my other projects are on my web page, which I think is linked in my signature.
> 
> 
> Eric


----------



## Holiday121

I will measure to see if I can go bigger but what is Kraft paper?

And Is it needed?


----------



## HopefulFred

Kraft paper is the brown paper backing used on faced insulation - also the brown paper of "brown paper packages tied up with strings." It is one of your favorite things, because it reflects high frequency sound while being transparent to mid and low frequency sound. Since highs are so easy to absorb (you and your furniture absorb them), reflecting them back into the room can be important to maintaining the spectral balance of reflected sound in the room.


----------



## Holiday121




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9150#post_22555301
> 
> 
> Kraft paper is the brown paper backing used on faced insulation - also the brown paper of "brown paper packages tied up with strings." It is one of your favorite things, because it reflects high frequency sound while being transparent to mid and low frequency sound. Since highs are so easy to absorb (you and your furniture absorb them), reflecting them back into the room can be important to maintaining the spectral balance of reflected sound in the room.




Thanks for the info. Do you buy it in rolls at Home Depot,


----------



## HopefulFred

looks like an office supply store might be the better choice - google can find it for you locally.


----------



## Holiday121

Ok thanks.


And for the fabric. I see people used curtains and all type if stuff. Does it matter when it comes to bass traps? Or does it have to be able to blow through it


----------



## mtbdudex




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9150#post_22555304
> 
> 
> 
> 
> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9150#post_22555301
> 
> 
> Kraft paper is the brown paper backing used on faced insulation - also the brown paper of "brown paper packages tied up with strings." It is one of your favorite things, because it reflects high frequency sound while being transparent to mid and low frequency sound. Since highs are so easy to absorb (you and your furniture absorb them), reflecting them back into the room can be important to maintaining the spectral balance of reflected sound in the room.
> 
> 
> 
> 
> 
> Thanks for the info. Do you buy it in rolls at Home Depot,
Click to expand...


I used Kraft paper because it was on hand (free







), you can also use 6mil plastic available @ Home Depot/Lowes/etc, both will achieve same intent as Holiday121 pointed out.


----------



## Holiday121




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9180#post_22555614
> 
> 
> I used Kraft paper because it was on hand (free
> 
> 
> 
> 
> 
> 
> 
> ), you can also use 6mil plastic available @ Home Depot/Lowes/etc, both will achieve same intent as Holiday121 pointed out.



Heading to Home Depot and Joann fabrics now ill let you know results


----------



## localhost127




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9150#post_22552801
> 
> 
> localhost127 made a good visual to grasp that....



you are probably referring to hannes' wonderfully elegant (albeit simplified for sake of explanation) drawing:



http://imgur.com/lclJJ.jpg%5B/IMG%5D


http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/177600-could-someone-help-out-interpreting-materials-gas-flow-properties-3.html 


or if actually discussing ocmlex acoustical impedance:



http://imgur.com/M5hsT.jpg%5B/IMG%5D


----------



## mattr6

Hello all,

I am looking for some affordable acoustical panels for my theater. I would like them to be about one inch in thickness and 2x3 or 3x3 feet. I plan on cutting, ( or having them pre-cut?) a small square in the middle where a sconce is. These are for looks as well as sound quality and I have seen some nice modern designs that I like online. I have relied on this forum for many things and was hoping you guys could point me to some good places to get the panels. Any help is much appreciated, thanks!


----------



## GIK Acoustics




> Quote:
> Originally Posted by *mattr6*  /t/255432/acoustical-treatments-master-thread/9180#post_22559685
> 
> 
> Hello all,
> 
> I am looking for some affordable acoustical panels for my theater. I would like them to be about one inch in thickness and 2x3 or 3x3 feet. I plan on cutting, ( or having them pre-cut?) a small square in the middle where a sconce is. These are for looks as well as sound quality and I have seen some nice modern designs that I like online. I have relied on this forum for many things and was hoping you guys could point me to some good places to get the panels. Any help is much appreciated, thanks!



Hey Matt,


Not too many manufacturers that I know will provide you custom sized panels, but I certainly know that we do. I would suggest calling up a few companies around and see what's possible.


I would recommend getting panels thicker than 1" so that they affect the low end as well as the top end in a room. 1" of any material will hardly do better than foam.


----------



## Jimbo2012

Doing a new build next month, the room area is open on one side into the living room.


should I insulate the three walls or will it have no effect being open?

 


It is on a slab single floor insulated ceiling.


In the bottom right of the drawing there will be a pocket door also


----------



## wse

Building Bass Traps?


----------



## colleycol

Need some clarification.


I bought OC 703 FRK for the wall behind the front screen.


I am hearing that the foil on this may not be optimal.


Is this material OK for the wall behind my acoustically transparent screen?


Thanks


----------



## Digital_Chris

I'm guessing that it depends on whether or not you have rear surround speakers in your room (7.1 setup). If you do, the foil will reflect high frequencies coming from those rear speakers which may not be optimal. I'm sure others will chime in with more reasons for why it is or isn't optimal but my answer should be a start


----------



## colleycol

So should I remove the foil all together?


Gosh, I should have asked before I bought it.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *colleycol*  /t/255432/acoustical-treatments-master-thread/9180#post_22570999
> 
> 
> So should I remove the foil all together?
> 
> Gosh, I should have asked before I bought it.



The foil is only applied on one side. If you wanted the reflectivity, you can face the foil in towards the room. If not, you can face the foil in towards the wall side. There should not be much of difference compared to normal 703 if comparing both against the wall (that is, with the foil facing the wall)


Don't go shooting yourself in the foot just yet.


----------



## Digital_Chris

Bingo!


----------



## pepar




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9180#post_22570861
> 
> 
> Building Bass Traps?



Yes, does that seem like it would be a problem?


----------



## colleycol




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9180#post_22571034
> 
> 
> The foil is only applied on one side. If you wanted the reflectivity, you can face the foil in towards the room. If not, you can face the foil in towards the wall side. There should not be much of difference compared to normal 703 if comparing both against the wall (that is, with the foil facing the wall)
> 
> Don't go shooting yourself in the foot just yet.



So I am guessing I don't want the reflection because I will have a 7.2 surround setup with 2 speakers in the back of the room. Correct?


Also whats the easiest way to mount the OC-703 on drywall?


Thanks guys!!


----------



## Brad Horstkotte

I can't really think of a scenario when you'd want reflection behind your speakers - maybe if using bipolar towers like Definitive?


I used long roofing nails to attach my OC-703 - can also use long drywall screws with fender washers.


----------



## Nightlord




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9180#post_22571941
> 
> 
> I can't really think of a scenario when you'd want reflection behind your speakers - maybe if using bipolar towers like Definitive?



There are numerous speakers where the reflex are part of the speaker design. Otherwise I agree, though I'm notso certain that definite won't benefit from reducing reflection unless you aim for an artificially deep soundstage.


----------



## sdurani




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/9180#post_22570980
> 
> 
> I'm guessing that it depends on whether or not you have rear surround speakers in your room (7.1 setup). If you do, the foil will reflect high frequencies coming from those rear speakers which may not be optimal. I'm sure others will chime in with more reasons for why it is or isn't optimal but my answer should be a start


Aside from reflections from the rear speakers, there can also be reflections from the side speakers, which could possibly be worse since they are closer to the front wall AND it is their off-axis response that will be reflected. In either case, I wouldn't want surround channel information bouncing off the front wall and interfering with the imaging in the critical front soundstage; I'd prefer that surround information stay in the surround field.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9180#post_22572869
> 
> 
> Aside from reflections from the rear speakers, there can also be reflections from the side speakers, which could possibly be worse since they are closer to the front wall AND it is their off-axis response that will be reflected. In either case, I wouldn't want surround channel information bouncing off the front wall and interfering with the imaging in the critical front soundstage; I'd prefer that surround information stay in the surround field.



100% agree with this. In most cases, you'd like there to be absorption.


The reason for facing the foil in on certain traps is when they are not in the direct path of speaker to listener, and say if you have carpet and two walls full of absorption, it may start to sound too "dead". Others also just prefer a more lively room and want to get more bass trapping without absorbing more highs. Similarly, you can put slats on the front of absorption to still get some reflectivity while still absorbing the low end.


> Quote:
> Originally Posted by *colleycol*  /t/255432/acoustical-treatments-master-thread/9180#post_22571866
> 
> 
> So I am guessing I don't want the reflection because I will have a 7.2 surround setup with 2 speakers in the back of the room. Correct?
> 
> Also whats the easiest way to mount the OC-703 on drywall?
> 
> Thanks guys!!



The easiest would likely be impaling clips. One used on each corner of each 24x48 batt of insulation.


----------



## Ankur

Hi. I have a multi purpose room that i want to treat for better acoustics. http://www.avsforum.com/t/1422049/how-do-i-optimize-performance 


Need you help in understanding where to start from. Would appreciate help from the experts here.


----------



## SierraMikeBravo

Regarding customizing panels...no one customizes more or has more fabrics and types of panels to choose from then Quest Acoustical Interiors.


Regarding 703 for the front wall...sure you can use it. However, make sure you do cover it up with acoustically transparent fabric to prevent a continuous stream of loose fiberglass fibers in the room.


----------



## colleycol




> Quote:
> Originally Posted by *SierraMikeBravo*  /t/255432/acoustical-treatments-master-thread/9180#post_22600344
> 
> 
> Regarding customizing panels...no one customizes more or has more fabrics and types of panels to choose from then Quest Acoustical Interiors.
> 
> Regarding 703 for the front wall...sure you can use it. However, make sure you do cover it up with acoustically transparent fabric to prevent a continuous stream of loose fiberglass fibers in the room.



Do I have to cover each panel individually or can I cover like a "sheet on the wall", like start from one end and unroll the fabric to the other end and cut? Repeat in lines


Also, spray adhesive to put the fabric on the OC?


----------



## SierraMikeBravo

Width of GOM FR 701 fabric is 66". Usuable width is 64" at best. Length is endertimend, but keep in mind, it isn't as easy as just "unrolling" it. If lighting hits it in certain spots, you'll see runs and other imperfections due to the installation. It's best to really use track to install fabric. Depends on the adhesive. I would use adhesive and tacks. Using strictly adhesive for long runs may be problematic. However, if you use the preferred method of tracking it, you won't need adhesive to install the fabric itself and you can manipulate the fabric.


----------



## vardo

colley, If I was doing it I would cover each panel individually, but that's just me. If you can cover them all, and it looks good go for it.


I myself would not use spray adhesive, as it will reduce absorption


vardo.


----------



## vardo




> Quote:
> Originally Posted by *mattr6*  /t/255432/acoustical-treatments-master-thread/9180#post_22559685
> 
> 
> Hello all,
> 
> I am looking for some affordable acoustical panels for my theater. I would like them to be about one inch in thickness and 2x3 or 3x3 feet. I plan on cutting, ( or having them pre-cut?) a small square in the middle where a sconce is. These are for looks as well as sound quality and I have seen some nice modern designs that I like online. I have relied on this forum for many things and was hoping you guys could point me to some good places to get the panels. Any help is much appreciated, thanks!



mattr6, Gik Acoustics advise is very good. You might look into ATS acoustics....they make custom panels for a very affordable price. And as GiK mentioned,

1" is to thin. ATS doesn't make 1" thick panels (2" and up). Just another place to try, not trying to take away any business from Gik Acoustics. I appreciate

his knowledge.


vardo


----------



## SierraMikeBravo

You'll find some very reputable acoustics companies do use adhesive across the entire stretch of fabric for each panel. Nothing wrong with it unless it is used to excess.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *SierraMikeBravo*  /t/255432/acoustical-treatments-master-thread/9180#post_22601772
> 
> 
> You'll find some very reputable acoustics companies do use adhesive across the entire stretch of fabric for each panel. Nothing wrong with it unless it is used to excess.



The largest problem with using adhesives is NOT that it can reflect. The biggest issue is that adhesives are very flammable, and can make cloth ignite easier than if there were no adhesive. If you are using adhesives, be sure to use fire retardant spray to make sure the panels won't instantly combust should the unthinkable happen.


This is why GIK uses acoustically transparent and flame retardant materials, as well as ECOSE Greensafe acoustic material to make sure you are in the safe zone as much as possible.


----------



## SierraMikeBravo

My standpoint was from an acoustical perspective only. I do believe most reputable companies in the industry are using environmentally safe as well as products that meet fire codes. However, a lot of them STILL use adhesive and are STILL very safe. Nice marketing though.


----------



## Ankur

Some help guys. Still waiting for your suggestions.


----------



## SierraMikeBravo

Hi Ankur,


Best place to start is ray trace the room. See where things need to be placed. Post that when completed and go from there.


----------



## Ankur




> Quote:
> Originally Posted by *SierraMikeBravo*  /t/255432/acoustical-treatments-master-thread/9210#post_22606337
> 
> 
> Hi Ankur,
> 
> Best place to start is ray trace the room. See where things need to be placed. Post that when completed and go from there.


Hi, what exactly do you mean by ray trace?


----------



## NicksHitachi




> Quote:
> Originally Posted by *Ankur*  /t/255432/acoustical-treatments-master-thread/9210#post_22606635
> 
> 
> 
> 
> Quote:
> Originally Posted by *SierraMikeBravo*  /t/255432/acoustical-treatments-master-thread/9210#post_22606337
> 
> 
> Hi Ankur,
> 
> Best place to start is ray trace the room. See where things need to be placed. Post that when completed and go from there.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hi, what exactly do you mean by ray trace?
Click to expand...


Assume sound travels like a ray of light or use mirror to locate probable high gain reflection points.


----------



## Ankur




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9210#post_22607079
> 
> 
> Assume sound travels like a ray of light or use mirror to locate probable high gain reflection points.


Thanks, along with the side walls, which other surfaces should i consider?


----------



## NicksHitachi

Ceiling, floor, and maybe back wall.


----------



## pepar




> Quote:
> Originally Posted by *Ankur*  /t/255432/acoustical-treatments-master-thread/9210#post_22607364
> 
> 
> Thanks, along with the side walls, which other surfaces should i consider?



If you have ever shot pool, think of bank shots. Angle of incidence equals angle of reflection.


Jeff


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9210#post_22607592
> 
> 
> Ceiling, floor, and maybe back wall.



Front wall ...


----------



## NicksHitachi




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9210#post_22607756
> 
> 
> 
> 
> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9210#post_22607592
> 
> 
> Ceiling, floor, and maybe back wall.
> 
> 
> 
> 
> Front wall ...
Click to expand...


----------



## erkq




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9210#post_22607753
> 
> 
> If you have ever shot pool, think of bank shots. Angle of incidence equals angle of reflection.
> 
> Jeff



Yes. I used the "mirror test". It's exactly what you think it would be. Put treatment where ever you can see a speaker from any seating position reflected in a mirror placed on the surface..


----------



## SierraMikeBravo

Since you have it drawn out already, it may be easiest to draw out the reflections and place panels accordingly. That way you can design the look before purchasing anything.


----------



## wse




> Quote:
> Originally Posted by *SierraMikeBravo*  /t/255432/acoustical-treatments-master-thread/9210#post_22608445
> 
> 
> Since you have it drawn out already, it may be easiest to draw out the reflections and place panels accordingly. That way you can design the look before purchasing anything.



Very nice theaters you build


----------



## Ankur

Okay! So that means i need to consider all the first reflection points. Should i do this for all the three seating positions?

And once it is figured out, what should be the height at which walls should be treated. The earlier threads mentioned from ground till ear level, but i have noticed a lot of other starting the treatment much above the ground level.


----------



## Nightlord

Don't know if my little app-in-the-making can be of any help.... there's no help on how to run it and it's in metric system... and it's made for centered position mainly... but it can take a drawing as backdrop, so it may be worth playing with...


latest version can be found here:
http://www.nattlorden.com/software/software.html 


I do intend to do more with it in time, but it's not currently my main project, but that does not mean I won't take feedback on it.


----------



## mtbdudex




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9210#post_22610168
> 
> 
> Don't know if my little app-in-the-making can be of any help.... there's no help on how to run it and it's in metric system... and it's made for centered position mainly... but it can take a drawing as backdrop, so it may be worth playing with...
> 
> 
> latest version can be found here:
> http://www.nattlorden.com/software/software.html
> 
> 
> I do intend to do more with it in time, but it's not currently my main project, but that does not mean I won't take feedback on it.



Does this run on Mac OS X?


----------



## mtbdudex




> Quote:
> Originally Posted by *Ankur*  /t/255432/acoustical-treatments-master-thread/9210#post_22610060
> 
> 
> Okay! So that means i need to consider all the first reflection points. Should i do this for all the three seating positions?
> 
> And once it is figured out, what should be the height at which walls should be treated. The earlier threads mentioned from ground till ear level, but i have noticed a lot of other starting the treatment much above the ground level.



For ref here is a ray tracing program and what it showed for 1st and 2nd row in my HT.



















You can generalize this to your HT.

Key is some people over absorb by putting too many panels where not needed.


Also, look at the ceiling.


----------



## NicksHitachi

hi Mtb,


Is that software available and how much does it cost?


----------



## Nightlord




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9210#post_22610330
> 
> 
> Does this run on Mac OS X?



It's a windows application based on .Net 3.5 - no idea if there's any emulators on OS X that runs such apps. The only Apple products I have myself run iOS, not OS X...


----------



## Nightlord

Mtb - that's quite cool. Always interesting to know how other people have solved the same thing. Using raytracing methods has been on my mind - quite fun to have one's ideas verified without having to code it first.










The more precision the tool has, the more precision the indata (room, placement, angles) has to have for the result to be valid, finding a useful balance is a tricky thing.


----------



## davey r

I have a question about how to treat a room with the lower 38'' of the entire perimeter of the room that is covered in wood panel (wainscotting) I have seen many done this way, chasen the dream theater by jchasen comes to mind. This is exactly the look I want, however it seems to go against what is recomended, meaning all the wood panels are reflective and they are below the ear, for the most part. What the wainscotting doesn't cover I would like to make cloth panels for such as what gpowers has done. Being that high on the wall I would guess they shouldn't have oc703 behind them correct? Poly batten instead? What's left of the front and rear wall surfaces I was going to use oc703, it's the side walls that have me confused. I have read a lot of this thread but haven't seen this adressed, it's pretty long maybe I missed it. Any tips would be great.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *Ankur*  /t/255432/acoustical-treatments-master-thread/9210#post_22610060
> 
> 
> Okay! So that means i need to consider all the first reflection points. Should i do this for all the three seating positions?
> 
> And once it is figured out, what should be the height at which walls should be treated. The earlier threads mentioned from ground till ear level, but i have noticed a lot of other starting the treatment much above the ground level.



Yes, consider all seating locations.


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9210#post_22609196
> 
> 
> Very nice theaters you build



Thank you!


----------



## SierraMikeBravo




> Quote:
> Originally Posted by *davey r*  /t/255432/acoustical-treatments-master-thread/9210#post_22625979
> 
> 
> I have a question about how to treat a room with the lower 38'' of the entire perimeter of the room that is covered in wood panel (wainscotting) I have seen many done this way, chasen the dream theater by jchasen comes to mind. This is exactly the look I want, however it seems to go against what is recomended, meaning all the wood panels are reflective and they are below the ear, for the most part. What the wainscotting doesn't cover I would like to make cloth panels for such as what gpowers has done. Being that high on the wall I would guess they shouldn't have oc703 behind them correct? Poly batten instead? What's left of the front and rear wall surfaces I was going to use oc703, it's the side walls that have me confused. I have read a lot of this thread but haven't seen this adressed, it's pretty long maybe I missed it. Any tips would be great.



Depends exactly where the placement of the panels is. I would consider using Quest perfsorber possibly...again depending where it is. Regarding wainscoting at that height, it will be an issue.


----------



## jbrown15

Would I be better off to use OC703 or Roxul safe and sound to build my DIY bass traps?


----------



## NicksHitachi




> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9210#post_22659610
> 
> 
> Would I be better off to use OC703 or Roxul safe and sound to build my DIY bass traps?





> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9210#post_22659610
> 
> 
> Would I be better off to use OC703 or Roxul safe and sound to build my DIY bass traps?





> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9210#post_22659610
> 
> 
> Would I be better off to use OC703 or Roxul safe and sound to build my DIY bass traps?



I wont speak to "better" but in my area roxul is cheaper. A lot cheaper -25-40% depending on your hookups.


However it is floppy and requires a frame so you might lose some effective area..... This might mitigate the cost offset.


----------



## Skylinestar

Is there anyone who sit close to their subwoofer? Since it's nearfield, the frequency response should be flat and not much affected by the room?

I'm wondering this because theoretically small room is bad for bass, but since every speakers and subwoofers are nearfield, will the sound be more accurate?


----------



## mtbdudex

Near filed is measured at 1" and 12" for subs, beyond that and room modes interact with the bass wave.

How close are you?


What I've learned is my broadband bass traps tame the peaks / valleys somewhat, really help on modal ringing reducing.

However, for multiple seats multiple subs is best approach for flat sub response across them.



Sent from my 32GB iPhone4 using Tapatalk


----------



## GIK Acoustics

A speaker or sub being "nearfield" doesn't make it more or less prone to room problems. The room will equally effect a pair of mains, nearfield, or far field monitors/speakers. Room acoustics does not judge speakers before imparting it's effects.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9210#post_22659610
> 
> 
> Would I be better off to use OC703 or Roxul safe and sound to build my DIY bass traps?



How thick are you building them? If 2-6" thick, OC703 would be 'better' - thicker than that, Safe'n'Sound would be 'better'. However, the differences are not immense and Safe'n'Sound is cheaper. If you can afford it - 6.5" (two batts of Roxul) thick traps of the Safe'n'Sound would produce some great results.


----------



## FOH




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9210#post_22669979
> 
> 
> Is there anyone who sit close to their subwoofer? Since it's nearfield, the frequency response should be flat and not much affected by the room?
> 
> I'm wondering this because theoretically small room is bad for bass, but since every speakers and subwoofers are nearfield, will the sound be more accurate?





> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9210#post_22670471
> 
> 
> A speaker or sub being "nearfield" doesn't make it more or less prone to room problems. The room will equally effect a pair of mains, nearfield, or far field monitors/speakers.













Did this not come out right? As written, this isn't correct, and just wanting to maintain clarity for those inquiring.


In a typical room, proximity to the source is everything for both measurements and listening. Using the example that th OP inquired about, ... yes, the closer to the sub, one encounters less "room", and more sub. All the way to an inch off the cone for a nearfield measurment,....minimizing the room relative to the driver's direct sound.


Overlaying the LP measurement, and the nearfiel measurement of a sealed sub system, one can get a good idea of the freq onset of Pressure Vessel Gain (PVG). You can illustrate how and where the room begins "giving back", as any freq with half a wavelength bigger than will fit into the room won't exhibit the traditional roll-off associated with subs beneath the knee. Free lunch, yada yada. *


Also, another exception is...critical distance; the point of equal energy from both the direct energy and reverberant energy. Now it's somewhat murky due to freq dependent directionality, but that's beyond the scope of this discussion.



You guys are great at GIK, and I intend no dis-respect,....just want to clarify.


Thanks


*for those interested, ping me,... as there's another killer advantage at play here, don't want to muddy up this discussion


----------



## Dennis Erskine




> Quote:
> Is there anyone who sit close to their subwoofer? Since it's nearfield, the frequency response should be flat and not much affected by the room?
> 
> I'm wondering this because theoretically small room is bad for bass, but since every speakers and subwoofers are nearfield, will the sound be more accurate?


Do not place a subwoofer such that the driver is aimed into the seating locations (in a residential sized room). If you do, you should place a 1" thick piece of 1.5 PCF fiberglass in front of the driver. Sometimes it requires 2".


> Quote:
> wavelength bigger than will fit into the room


FOH...let's avoid this terminology. Perhaps better as where the x.x wave length is longer than the room dimension. There is too much misunderstanding about "bass not fitting into a room".


----------



## Nightlord




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9210#post_22677582
> 
> 
> Do not place a subwoofer such that the driver is aimed into the seating locations (in a residential sized room). If you do, you should place a 1" thick piece of 1.5 PCF fiberglass in front of the driver. Sometimes it requires 2".



+1


Needing to do that myself, as my subwoofers are triangular, was looking to use 70mm even... which is close to 3". ( I like overkill.







)


----------



## Skylinestar




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9210#post_22677582
> 
> 
> Do not place a subwoofer such that the driver is aimed into the seating locations (in a residential sized room). If you do, you should place a 1" thick piece of 1.5 PCF fiberglass in front of the driver. Sometimes it requires 2".


What's wrong with having the driver aimed into the listening position?


----------



## Nightlord




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9240#post_22677748
> 
> 
> What's wrong with having the driver aimed into the listening position?



You may bounce other sound too early towards listener as well.


----------



## FOH




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9210#post_22677582
> 
> 
> FOH...let's avoid this terminology. Perhaps better as where the x.x wave length is longer than the room dimension. There is too much misunderstanding about "bass not fitting into a room".




"as any freq with half a wavelength bigger than will fit into the room"




I'm guessing many understood, but you're right, I'm sure there's those that misunderstand. I certainly didn't want to muddy up the waters. Many savvy enthusiast don't get it, muct too much confusion and the whole point is clarity.


Typically, I'm more clear (read verbose) with regard to PVG, like I did in this excerpted post;


"Pressure Vessel Gain (PVG), or room gain, is the scenario whereby the longest dimension of the room can no longer support full propagation of the waveform. At this point, the acoustic propagation transitions to acoustic pressurization. A typical myth is a small cabin cannot support the lowest frequencies.... nothing could be further from the truth. The manner in which the sound is reproduced into the space changes from a normal cyclic propagation, to pressurization because the wavelengths are too big for the space. The frequency at which this occurs is approximately the point whereby half the wavelength of a given frequency is equal to the rooms longest dimension. So, a 20 hz frequency has a wavelength 56.5 feet. So half of that, 28.25 feet, is the point of transition. Any frequency below that point pressurizes the room, and any frequency above that point propagates freely. So in this room that's approximately 28 feet in the longest dimension, from 20 hz downward, the room gives back acoustically. This is room gain, cabin gain, or more specifically PVG...Pressure Vessel Gain.


At this frequency, the results are a gain in acoustic pressures in the room that grows as the frequency decreases. This acoustic support reciprocity, is theoretically 12db per octave. The percentage of the 12 db/octave gain one achieves, entirely depends on the integrity of the boundary walls and surfaces. If it was the theoretical concrete bunker, a full 12db/octave boost would occur. Typically, somewhere between 6-10 db octave could result. Also, in addition to the walls and surfaces flexing, other aspects may affect the point at which room gain begins. Furniture, cabinets etc, anything that consumes a certain measure of cubic feet, may slightly alter the transition frequency merely because the items take up space.


This acoustic pressurization, room gain, is the proverbial free lunch. It is essentially headroom that's thrown back into the system. And unlike horn subs, the distortions and non-linearities are not magnified. An IB sub system is a sealed alignment. Sealed alignments roll off second order. Room gain also is second order. So one can see how integrating a sealed alignment may offer substantial benefit when attempting to integrate the system to the room via time and frequency equalization. The -3db point of the IB, may typically be deeper than the transition point where room gain begins. Properly adjusted, this would result in substantial headroom added back in for significant capability for the big LFE effects."


Thanks


----------



## Nightlord

Right. This is when rubber seals around doors starts to get interesting. The stiffer and the better sealed, the better the pressurization. That's why my livingroom stereo could never yield the ULF response that the system itself had capability of, but it is one of the things I really hope to achieve with "The Larch" theater.


----------



## mtbdudex




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9240#post_22680685
> 
> 
> Right. This is when rubber seals around doors starts to get interesting. The stiffer and the better sealed, the better the pressurization. That's why my livingroom stereo could never yield the ULF response that the system itself had capability of, but it is one of the things I really hope to achieve with "The Larch" theater.



These are the little details that when building HT many don't know about, including me 5+ years ago. Completely sealed means no path for sound to leak out.

I've got can lights in the ceiling, those "leak" into the space above since I did not build backer boxes around them, so even when I put a door on my basement HT I'll never get the full effect of PV gain.


----------



## FOH

Those mammoth wavelengths are so long, the leaks you're discussing would be much more detrimental to sound egress/sound proofing, than diminishing the benefits of PVG.


----------



## Nightlord




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9240#post_22680869
> 
> 
> Those mammoth wavelengths are so long, the leaks you're discussing would be much more detrimental to sound egress/sound proofing, than diminishing the benefits of PVG.



There's no need to compete in the "what's worse" game, one can discuss each issue seperately even if there are larger gains to be made. After all, people discuss different DACs...


----------



## FOH




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9240#post_22680886
> 
> 
> There's no need to compete in the "what's worse" game, one can discuss each issueseparatelyy even if there are larger gains to be made. After all, people discuss different DACs...




No "what's worse" game here, but I do understand your point.


We can discuss themseparatelyrately, however that doesn't change the accuracy of my contention.


If one can enjoy ~9dB/octave PVG below the 1, 0, 0 mode, in a typical 2x4 wood stud/sheetrock space (a space that's diaphragmatic and quite lossy), ... I'd recommend focusing one's energy elsewhere. That's my opinion based on my experiments/ measurements. Sealing a room tightly is something I've no experience with in my home, so I can't speak to any details in that realm.


I currently have no "within the home" isolation needs. Also, my home is a brick ranch, with side-to-side neighbors about 100 feet either direction of my listening room. Neighbors front to back are several hundred feet away, so I'd characterize my external iso needs as minimal as well. With (4)18s, (4)15s, plus dual 12" LCRs, the LF/ULF can travel however. During cold, calm nights, while out with our dog, I have certainly contemplated a fully iso'd HT build(out) at some time.


Thanks


----------



## giomania




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9200_100#post_22679207
> 
> 
> "as any freq with half a wavelength bigger than will fit into the room"
> 
> I'm guessing many understood, but you're right, I'm sure there's those that misunderstand. I certainly didn't want to muddy up the waters. Many savvy enthusiast don't get it, muct too much confusion and the whole point is clarity.
> 
> Typically, I'm more clear (read verbose) with regard to PVG, like I did in this excerpted post;
> 
> "Pressure Vessel Gain (PVG), or room gain, is the scenario whereby the longest dimension of the room can no longer support full propagation of the waveform. At this point, the acoustic propagation transitions to acoustic pressurization. A typical myth is a small cabin cannot support the lowest frequencies.... nothing could be further from the truth. The manner in which the sound is reproduced into the space changes from a normal cyclic propagation, to pressurization because the wavelengths are too big for the space. The frequency at which this occurs is approximately the point whereby half the wavelength of a given frequency is equal to the rooms longest dimension. So, a 20 hz frequency has a wavelength 56.5 feet. So half of that, 28.25 feet, is the point of transition. Any frequency below that point pressurizes the room, and any frequency above that point propagates freely. So in this room that's approximately 28 feet in the longest dimension, from 20 hz downward, the room gives back acoustically. This is room gain, cabin gain, or more specifically PVG...Pressure Vessel Gain.
> 
> At this frequency, the results are a gain in acoustic pressures in the room that grows as the frequency decreases. This acoustic support reciprocity, is theoretically 12db per octave. The percentage of the 12 db/octave gain one achieves, entirely depends on the integrity of the boundary walls and surfaces. If it was the theoretical concrete bunker, a full 12db/octave boost would occur. Typically, somewhere between 6-10 db octave could result. Also, in addition to the walls and surfaces flexing, other aspects may affect the point at which room gain begins. Furniture, cabinets etc, anything that consumes a certain measure of cubic feet, may slightly alter the transition frequency merely because the items take up space.
> 
> This acoustic pressurization, room gain, is the proverbial free lunch. It is essentially headroom that's thrown back into the system. And unlike horn subs, the distortions and non-linearities are not magnified. An IB sub system is a sealed alignment. Sealed alignments roll off second order. Room gain also is second order. So one can see how integrating a sealed alignment may offer substantial benefit when attempting to integrate the system to the room via time and frequency equalization. The -3db point of the IB, may typically be deeper than the transition point where room gain begins. Properly adjusted, this would result in substantial headroom added back in for significant capability for the big LFE effects."
> 
> Thanks



Interesting.


I had been recently considering the addition of two tapped horn subwoofers to my setup, but decided additional research was required. I currently have four sealed Seaton SubMersive HP subwoofers in my basement theater, that is ~27 x 21 x 8; the room is not completely sealed, but I do feel some modest pressurization sensations occasionally. I am happy with the performance, but desire increased performance at lower frequencies. It would seem that sticking with sealed subs versus ported or tapped horns would be easier to integrate with respect to time and frequency equalization.


Did I understand that correctly?


Thanks.


Mark


----------



## Nightlord




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9240#post_22685241
> 
> 
> We can discuss themseparatelyrately










funny! It's the iPad spacebar that sometimes don't register the fast taps. A regular keyboard is superior, but then I can't sit where I want to.


----------



## Mark Seaton




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/9240#post_22685294
> 
> 
> I had been recently considering the addition of two tapped horn subwoofers to my setup, but decided additional research was required. I currently have four sealed Seaton SubMersive HP subwoofers in my basement theater, that is ~27 x 21 x 8; the room is not completely sealed, but I do feel some modest pressurization sensations occasionally. I am happy with the performance, but desire increased performance at lower frequencies. It would seem that sticking with sealed subs versus ported or tapped horns would be easier to integrate with respect to time and frequency equalization.
> 
> 
> Did I understand that correctly?
> 
> 
> Thanks.
> 
> 
> Mark



Hi Mark,


If you are after more bass you need to first experiment with raising the sub level, and then probably just add a manual EQ for the subs of some form. I had measured the 4 combined SubMersives to be ~5dB down at 10Hz at the listening position after Audyssey's calibration, and the mic I had with is rolled off slightly by 10Hz itself. There was only about 2dB of peaking over the 20Hz level up past 100Hz. More capability only gives more impact if you ask it from the subs. An EQ with shelf filter capabilities make this sort of adjustment very simple and some even have presets you can select for those case you want to amp it up or even when you don't want to give anyone upstairs an unintended foot-massage.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *FOH*  /t/255432/acoustical-treatments-master-thread/9210#post_22675884
> 
> 
> In a typical room, proximity to the source is everything for both measurements and listening. Using the example that th OP inquired about, ... yes, the closer to the sub, one encounters less "room", and more sub. All the way to an inch off the cone for a nearfield measurment,....minimizing the room relative to the driver's direct sound.



FOH, I think you misunderstood why I was replying as such. Being 5 foot or 10 foot away from a speaker doesn't make it more or less prone to room problems. Yes, measuring from 2" is a different story than 10 feet, though the question wasn't posed in a way that made me believe he wasn't inquiring for measuring purposes. Obviously it is impractical to sit 2" away from a speaker as to get less of the "room" sound (and room resonance and SBIR still happens regardless of where you sit, so there still is those anomalies you'll have to deal with no matter where you sit). Yes, the relative SPL of resonance when compared with SPL of the sub will be different pending where you are sitting, but that doesn't mean those acoustic problems aren't happening, nor does it mean they can't destroy the response you hear. I hope that makes more sense!


----------



## Nightlord




> Quote:
> Originally Posted by *Mark Seaton*  /t/255432/acoustical-treatments-master-thread/9240#post_22687061
> 
> 
> I had measured the 4 combined SubMersives to be ~5dB down at 10Hz at the listening position after Audyssey's calibration, and the mic I had with is rolled off slightly by 10Hz itself. There was only about 2dB of peaking over the 20Hz level up past 100Hz.



So then you just need a boost circuit to lift you 10Hz by 20-30dB so you get some useful ULF. Preferrably one that can shape the boost curve, but I suppose they are rare unless people make them themselves.


----------



## giomania




> Quote:
> Originally Posted by *Mark Seaton*  /t/255432/acoustical-treatments-master-thread/9200_100#post_22687061
> 
> 
> Hi Mark,
> 
> If you are after more bass you need to first experiment with raising the sub level, and then probably just add a manual EQ for the subs of some form. I had measured the 4 combined SubMersives to be ~5dB down at 10Hz at the listening position after Audyssey's calibration, and the mic I had with is rolled off slightly by 10Hz itself. There was only about 2dB of peaking over the 20Hz level up past 100Hz. More capability only gives more impact if you ask it from the subs. An EQ with shelf filter capabilities make this sort of adjustment very simple and some even have presets you can select for those case you want to amp it up or even when you don't want to give anyone upstairs an unintended foot-massage.



Thanks for the input, Mark. Maybe I should just stay off the "the new master list of bass in movies with frequency charts" thread!










Let me clarify that when "normal" bass (~30 Hz???) hits in movies, it brings a smile to my face; that is after I have landed from the sometimes inevitable jump out of my seat!


I shall experiment with the bass levels over the holidays, as I will be off. Funny story about subwoofer levels: We had a couple over to watch The Cabin In The Woods, and I was finding myself disappointed with the bass. It dawned on me to check the sub levels, and they had been reset to -12.0 dB (the Audyssey calibrated setting) from the -7.0 dB (Mark's adjusted setting). What a difference that made! This phenomenon occurs on my Denon AVR-4311 CI sometimes after a brief power outage.


Mark


----------



## FOH




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9240#post_22687632
> 
> 
> FOH, I think you misunderstood why I was replying as such. Being 5 foot or 10 foot away from a speaker doesn't make it more or less prone to room problems. Yes, measuring from 2" is a different story than 10 feet, though the question wasn't posed in a way that made me believe he wasn't inquiring for measuring purposes.



I appreciate the added clarity.



The OP asked; ... "Does anyone sit close to their subs?"



You replied; .... "A speaker or sub being "nearfield" doesn't make it more or less prone to room problems. The room will equally effect a pair of mains, nearfield, or far field monitors/speakers."


I want to make clear that a speaker or sub nearfield _*is*_ less prone to room problems. In my experience, even in your clarification statement above runs counter to my experiments/measurments. Being 5 feet away does lessen the significance of the ever present acoustic distortions. Yes, they never go away, however their relative significance is lessened in the nearfield.




A compartive example below.


There's black and white;

.. ie, opposite tri-corner measurements, stimulating every mode to it's maximum, compared to a mic measurement right up near the cone. The acoustic distortions still reside in the room, but they're rendered insignificant due to relative level. That's black and white.


There's shades of grey;

.. ie, relative far field typical LP in domestic living room, compared to relative nearfield in the same domestic setting. Again, the acoustic distortions don't change, however their significance due to relative level does.




Where am I wrong? Again, I merely wanted clarity for those following along, myself included.


Thank you


----------



## FOH




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9240#post_22685358
> 
> 
> 
> 
> 
> 
> 
> 
> funny! It's the iPad spacebar that sometimes don't register the fast taps. A regular keyboard is superior, but then I can't sit where I want to.













It's my wife's laptop. Her "ieSpell" or whatever, is bizaare,....it corrects, but adds words, strings them together etc, weird and total junk.










Never owned an ipad or similar. Hell, just traded in my flip phone recently for an Android Samsung. Being a photog for several decades, the best thing is having a decent camera w/me at all times.


btw; saw a Christmas card recently whereby all family members had the phones out and thumbing away .... quite funny really.




Thanks for the heads up


----------



## Mark Seaton




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9240#post_22687838
> 
> 
> 
> 
> Quote:
> Originally Posted by *Mark Seaton*  /t/255432/acoustical-treatments-master-thread/9240#post_22687061
> 
> 
> I had measured the 4 combined SubMersives to be ~5dB down at 10Hz at the listening position after Audyssey's calibration, and the mic I had with is rolled off slightly by 10Hz itself. There was only about 2dB of peaking over the 20Hz level up past 100Hz.
> 
> 
> 
> 
> So then you just need a boost circuit to lift you 10Hz by 20-30dB so you get some useful ULF. Preferrably one that can shape the boost curve, but I suppose they are rare unless people make them themselves.
Click to expand...


If you want 10Hz elevated by 15-20dB, that's certainly an option. As you approach reference level though, you want a more flat response. The point of my post was not that more 10Hz was needed, rather that there was plenty of extension and capability, and the desired effects would best be had by some "seasoning to taste" of the response. Audyssey's Dynamic EQ is another option to experiment with, especially if you dial back the amount of boost applied.


----------



## Mark Seaton




> Quote:
> Originally Posted by *giomania*  /t/255432/acoustical-treatments-master-thread/9240#post_22688786
> 
> 
> 
> 
> Quote:
> Originally Posted by *Mark Seaton*  /t/255432/acoustical-treatments-master-thread/9200_100#post_22687061
> 
> 
> Hi Mark,
> 
> If you are after more bass you need to first experiment with raising the sub level, and then probably just add a manual EQ for the subs of some form. I had measured the 4 combined SubMersives to be ~5dB down at 10Hz at the listening position after Audyssey's calibration, and the mic I had with is rolled off slightly by 10Hz itself. There was only about 2dB of peaking over the 20Hz level up past 100Hz. More capability only gives more impact if you ask it from the subs. An EQ with shelf filter capabilities make this sort of adjustment very simple and some even have presets you can select for those case you want to amp it up or even when you don't want to give anyone upstairs an unintended foot-massage.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks for the input, Mark. Maybe I should just stay off the "the new master list of bass in movies with frequency charts" thread!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Let me clarify that when "normal" bass (~30 Hz???) hits in movies, it brings a smile to my face; that is after I have landed from the sometimes inevitable jump out of my seat!
> 
> 
> I shall experiment with the bass levels over the holidays, as I will be off. Funny story about subwoofer levels: We had a couple over to watch The Cabin In The Woods, and I was finding myself disappointed with the bass. It dawned on me to check the sub levels, and they had been reset to -12.0 dB (the Audyssey calibrated setting) from the -7.0 dB (Mark's adjusted setting). What a difference that made! This phenomenon occurs on my Denon AVR-4311 CI sometimes after a brief power outage.
> 
> 
> Mark
Click to expand...


Not a problem at all Mark. I just wanted to point out that extension wasn't a part of what you were hearing, and this really comes down to playback levels, low frequency room acoustics/decay times, and some seasoning to taste. Sometimes a little tweaking of the levels do the trick. An external EQ for the subs can be another good way to achieve this, just as you can also experiment with Audyssey's Dynamic EQ, especially if you dial back the effect.


While it's important to know where your starting point was and how to get back there if needed, you shouldn't be afraid of making some adjustments. While a narrow peak or dip of 2-4dB isn't very audible and we see that range of variation all the time, when you make such adjustments to a couple octaves at a time by changing the subwoofer level, it makes for very audible changes.


Circling this discussion detour back to acoustics, how long the sound lingers in the rooms of different size, construction and treatment, aka the decay times are the reason a similar measured frequency response can sound rather different in different spaces.


----------



## Nightlord




> Quote:
> Originally Posted by *Mark Seaton*  /t/255432/acoustical-treatments-master-thread/9240#post_22689361
> 
> 
> If you want 10Hz elevated by 15-20dB, that's certainly an option. As you approach reference level though, you want a more flat response.



I haven't detail studied the fletcher-munson curves that much, but I have a feeling that also at ref you need a quite substantial lift. I can understant that one might want to level out to save cone excursion or neighbour irritation, but not from a reproduction point of view.


----------



## GIK Acoustics

FOH,


I never stated you were wrong, nor did I join up in conversation to prove you wrong. The relative level of acoustic distortions due to rooms are of course due to your position relative to the speakers. We both agree










Being 4 feet away from speakers is more than enough distance to inherit 'bad' acoustic distortions from what I've seen - regardless of a nearfield speaker or not. I'm not disagreeing that it might be worse at 10 or 20 feet, but I am saying that a typical minimum listening distance is a long enough distance that most acoustic distortions can impart their effects. Considering most of the work I've done is in studios where people sit one to two yards from their nearfield speakers, I can certainly say, the room's effects are still extensively problematic. It may be "worse" farther away, but that doesn't mean they are "better" closer to the speaker, only different in relative dB SPL.


Of course, I appreciate your response as well, and asking me to clarify my original statement was warranted as not to confuse others. Though now, I think we've both stated our points. We can continue over PM with some cool measurements to show each other our points in a more convincing manner. I'm not very articulate so data speaks better than words for me.


----------



## FOH

Thanks, no prob


----------



## colleycol

Has anyone discovers a fabric that can be had locally for covering OC 703? I want to pick some up tomorrow.


----------



## jbrown15




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9210#post_22670501
> 
> 
> How thick are you building them? If 2-6" thick, OC703 would be 'better' - thicker than that, Safe'n'Sound would be 'better'. However, the differences are not immense and Safe'n'Sound is cheaper. If you can afford it - 6.5" (two batts of Roxul) thick traps of the Safe'n'Sound would produce some great results.



I would be building them 12"x12". And would I be better off putting up an acoustical panel on the very back wall of the theater behind the seats or a diffuser? along with bass traps in the corners.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9240#post_22705710
> 
> 
> I would be building them 12"x12". And would I be better off putting up an acoustical panel on the very back wall of the theater behind the seats or a diffuser? along with bass traps in the corners.



The 12x12 corner ones will work well with Safe'n'Sound, though I would recommend doing 16" square if its possible. Roxul makes 16" wide batts so this might be an easy construction.


Also, it would really depend. Diffusion can really give a great sound to a room, but if your bass is out of control it is more important to get that controlled IMO. There's a few options you could do:


Build the corner bass traps and see how your bass response sounds. If all is well and you want to do diffusion, then go for it.

-OR-

Pick one and go with it

-OR-

Build diffusers with bass traps behind (or you can consider it bass traps with diffusion on the front)


Another option is to do something like our Scatter Plate ( http://gikacoustics.com/product/gik-acoustics-scatter-plate/ ) to get high frequency scattering, coupled with absorption.


----------



## avtexan

I received some fabric samples from GOM today. I Like the Anchorage Mulberry but I have read some post that say it is OK for panels and some say it is not. In my space I will have 2" material on the side walls and 4" in the rear. Will the Anchorage be OK in this application or will it significantly reduce the effectiveness of my treatments? The speakers will be in the columns and not covered by the Anchorage.


How about the false wall? I will have bass traps and 2" material in the front behind an AT screen. Is Anchorage OK here?


I have heard of people using triple velvet. Is this AT? Is this better or worse than FR701?


----------



## HaroldKumar

  


I am going to try some diffusion in my small theater room. I've already got bass traps on all the corners and I have 3 subs. Low end is awesome.


The room is 10 feet high, 15 feet long and 8.5 feet wide. Seating position is 7 feet from back wall.


The blue sofa is the sweet spot so I am thinking diffusion on the back wall and possibly on the side walls.


I have designs for 3 two foot n11 panels, or one 6 ft n31 panel for the back wall. I will be making panels out of gator board and stuffing back cavities with OC703.


I was going to buy commercial panels but I have access to an excellent local carpenter who needs the work.


The N11 panels would be 6" deep and the n31 would be 9" deep. I've read conflicting information about whether its better to go with one panel or with repeating panels.


So question 1 is what's best, 1 panel or 3 panels? The design of the n31 allows for deeper wells and better performance?


Question 2 is would it benefit to put diffusion on the back side walls and door?


And last question is the design I have is for 32" tall panels. The thinking is since a lot of sound would be caught by the sofa, the 32" panel height would give a thick enough horizontal plain of diffusion. say 1 foot below couch top and 20" above. Thoughts?


----------



## Nightlord

With front speakers that close to the side walls, I'd suggest absorption/reflex prevention rather than diffusion. "Gills" aimed towards speakers stuffed with insulation would be my tip.


Here's an example of it:


----------



## NicksHitachi




> Quote:
> Originally Posted by *colleycol*  /t/255432/acoustical-treatments-master-thread/9240#post_22705544
> 
> 
> Has anyone discovers a fabric that can be had locally for covering OC 703? I want to pick some up tomorrow.




Burlap, at any fabric store. Its flammable though so use at own discretion.


----------



## HaroldKumar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9240#post_22721494
> 
> 
> With front speakers that close to the side walls, I'd suggest absorption/reflex prevention rather than diffusion. "Gills" aimed towards speakers stuffed with insulation would be my tip.
> 
> Here's an example of it:



Those gills are a good idea, I can see how that will keep the sound waves (rocks) from skipping off the water. I have experimented with different first reflection treatment, but have not thought of gills, I will try that!


But with this specificproject, I am talking about diffusion placed *behind* the seating position, primarily I've seen QRDs used on the back wall, and sometimes on the sides walls behind the first reflection points.


----------



## Nightlord

Diffusion behind is a good idea yes, sorry I didn't pick it up, guess I mostly looked at the plan.


----------



## HaroldKumar

Well I'm glad you commented because I really like the gills idea.


----------



## Nightlord




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9270#post_22723097
> 
> 
> Well I'm glad you commented because I really like the gills idea.










it's being used more and more frequently here in Sweden. I thought I would have to build them too, but according to my acoustics consultant, my room is wide enough to warrant diffusion on the sides instead ( which diminished the cost of having him too, in a way ).


----------



## HT_SoulMan




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9240#post_22677998
> 
> 
> You may bounce other sound too early towards listener as well.




A down firing subwoofer pointing to a riser filled with sand is a option?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9270#post_22723097
> 
> 
> Well I'm glad you commented because I really like the gills idea.



Yes, these are typically called "sawtooth" walls (at least from what I've seen). They're really great when coupled with diffusion as instead of absorbing the early reflections, you can send them to the rear of the room to be diffused and returned at a later time, which will keep the liveliness of the room while providing a much more balanced, neutral sound.


----------



## Nightlord




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9270#post_22724764
> 
> 
> Yes, these are typically called "sawtooth" walls (at least from what I've seen). They're really great when coupled with diffusion as instead of absorbing the early reflections, you can send them to the rear of the room to be diffused and returned at a later time, which will keep the liveliness of the room while providing a much more balanced, neutral sound.



I'm not sure the two are completely the same. These aren't meant just to bounce the sound off, they are open on the short end towards the speakers and are to be filled with insulation (or other absorbing material). Is that common practice with your "sawtooth" walls?


(Gill-absorber is what this has been labeled as in Sweden )


----------



## HaroldKumar

My room with speakers so close to sidewalls it makes sense to try a custom gill assembly at the first reflection point. Since it's so close to wall and I have monitors the gill trap will be pretty small and easy to build with some black foam board, oc703 and hot glue.


But getting back to the real project is the diffusors. Did anyone have any comments on the three N11 panels vs the one N31 panel? The carpenter has slotted time for this now and I have to decide.


----------



## Nightlord

I'd go for the N31. If nothing else for no better reasons than that it's much better looking.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9270#post_22725697
> 
> 
> I'm not sure the two are completely the same. These aren't meant just to bounce the sound off, they are open on the short end towards the speakers and are to be filled with insulation (or other absorbing material). Is that common practice with your "sawtooth" walls?
> 
> (Gill-absorber is what this has been labeled as in Sweden )



Yes, that is the common design of what I've seen called "sawtooth" walls. Otherwise, they would work against their purpose and bounce sound back towards the listener!


They are very neat, and a great design concept for smaller rooms that don't have the room for fully angling the sidewalls.


----------



## Skylinestar

What could have cause a big valley and a serious null for my stereo bookshelf speakers? Each speaker is about 3.3 feet from sidewall, 2.6 feet from the wall behind speaker. Speaker is on 2 feet stand. Floor to ceiling height is about 10 feet. Sidewall to sidewall is about 16 feet.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9270#post_22733257
> 
> 
> What could have cause a big valley and a serious null for my stereo bookshelf speakers? Each speaker is about 3.3 feet from sidewall, 2.6 feet from the wall behind speaker. Speaker is on 2 feet stand. Floor to ceiling height is about 10 feet. Sidewall to sidewall is about 16 feet.



I would suspect SBIR (speaker boundary interference response) to be the culprit in this case (I would suspect this due to the extremely narrow dips). The easiest way to tell is through testing. I would recommend taking these steps to get to the bottom of it.


Do a standard test of the room (considering response changes day to day, I always recommend starting with this, even if you already have a measurement)

Move the speakers back or forwards one foot from their original position. Test.

Move the speakers towards or away from the sidewalls from their original position by a foot. Test.

Move the speakers up or down in height from their original position (you can use books to raise their height). Test.

Move the speakers back to their original position, and move the microphone back or forwards a foot. Test.


Whichever one of these variables changes will show which boundary interaction is giving you these nulls. More than one may be present. We do have an article you can read about SBIR on our website, here: http://gikacoustics.com/speaker-boundary-interference-response-sbir/ 


The solution would be to place bass traps between the speaker and whichever boundary is causing the problems.


----------



## Skylinestar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9270#post_22733527
> 
> 
> The solution would be to place bass traps between the speaker and whichever boundary is causing the problems.


How thick should the bass traps be to tackle the problem? 4" ? 6" ?


My local hardware shop has this Roxul RHT 80 : http://www.roxul.com/industrial/products/roxul+rht%C2%AE+30,+40,+60,+80,+100,+-c12-+150


----------



## GIK Acoustics

RHT 80 would work fine. Thicker is almost always better, so I would recommend 6" but 4" would likely do good as well. The farther the front surface of the absorber is to the wall, the lower in frequency it will absorb (typically). So 6" would go lower in frequency, or a 4" absorber with an air gap behind it would also go lower in frequency. So 6", if not, 4" with an air gap, and still if not, then a 4" absorber.


If the nulls are caused by both the front wall and the side walls as I suspect, some corner trapping (either broadband traps straddled on the corner, or superchunks) would help combat both sides of the problem.


Usually the packs of Roxul come in packages of 6 (48 sq feet). I would do a test of the room without any Roxul installed. Then, lean a batt of RHT against the sidewalls inbetween the speakers and sidewalls, inbetween the speakers and front walls, and one in each front corner, and do a test. _If the nulls are reduced_, but not enough, then try different combinations (for example, two high in each corner and one on each sidewall, etc). Or try doubling them up on one side (so 8" thick) and just testing the speaker individually. _If the nulls aren't reduced_, try different positions with the Roxul (first reflection points, or back wall corners, etc)


Edit: Are your speakers decoupled from the stands? Or are the stands decoupled from the floor? These can also cause nulls, but I've never seen nulls that deep due to coupling, I could see it as possible.


----------



## FOH




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9270#post_22725697
> 
> 
> I'm not sure the two are completely the same. These aren't meant just to bounce the sound off, they are open on the short end towards the speakers and are to be filled with insulation (or other absorbing material). Is that common practice with your "sawtooth" walls?
> 
> (Gill-absorber is what this has been labeled as in Sweden )



Never realized the mthod had a name.


I've posted about such an approach many times. Grazing angles and effectiveness of sidewall absorbers is important, and often over-looked. I've found a variety of methods for "catching" that incident energy, one such very much akin to what you posted.


A side benefit is it absorbs in one direction, and reflects in the other. That energy is nice to keep bouncing around, but the early sidewall stuff,...especially within the first couple dozen millisec, is detrimental in clarity and it's beneficial to lessen it's level (with absorption or diffusion), or re-direct and delay it's arrival.


I've found simply exposing the sides of the absorbent panels, staggering them like lap-board siding, with each new edge facing the speakers works great too.

Rigid 703, wrapped in fabric, no frame. This is how my ceiling is config'd too. The incident energy sees multiple panel edges, in addition to the remainder of the panel.



Thanks


----------



## pepar

I didn't know that the front "edges" were absorption, and I thought the angles were such that the listening area received no first reflections.


Jeff


----------



## FOH




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9270#post_22735295
> 
> 
> I didn't know that the front "edges" were absorption, and I thought the angles were such that the listening area received no first reflections.
> 
> Jeff



yep;



> Quote:
> "Gills" aimed towards speakers stuffed with insulation



The walls are directional, energy one way gets absorbed, stuff from the other direction gets reflected. As I stated, ceiling tretments work this way too.


----------



## Skylinestar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9270#post_22734651
> 
> 
> RHT 80 would work fine. Thicker is almost always better, so I would recommend 6" but 4" would likely do good as well. The farther the front surface of the absorber is to the wall, the lower in frequency it will absorb (typically). So 6" would go lower in frequency, or a 4" absorber with an air gap behind it would also go lower in frequency. So 6", if not, 4" with an air gap, and still if not, then a 4" absorber.
> 
> If the nulls are caused by both the front wall and the side walls as I suspect, some corner trapping (either broadband traps straddled on the corner, or superchunks) would help combat both sides of the problem.
> 
> Usually the packs of Roxul come in packages of 6 (48 sq feet). I would do a test of the room without any Roxul installed. Then, lean a batt of RHT against the sidewalls inbetween the speakers and sidewalls, inbetween the speakers and front walls, and one in each front corner, and do a test. _If the nulls are reduced_, but not enough, then try different combinations (for example, two high in each corner and one on each sidewall, etc). Or try doubling them up on one side (so 8" thick) and just testing the speaker individually. _If the nulls aren't reduced_, try different positions with the Roxul (first reflection points, or back wall corners, etc)
> 
> Edit: Are your speakers decoupled from the stands? Or are the stands decoupled from the floor? These can also cause nulls, but I've never seen nulls that deep due to coupling, I could see it as possible.


For your info, my room is fully brick-concrete, which is a reflection nightmare for many audiophile. I know many people have good result after adding bass traps (6" of OC703) but their rooms are NOT made of bricks, just plain wood frame and board instead. Therefore, I would like to know the effectiveness of bass trap in a room like mine...maybe I need 12" of bass trap to be effective?


Will denser material work better? Will RHT100 or RHT150 be more effective?


Is it OK to leave the Roxul batt plastic wrapping on for bass trap?


Speakers have BluTack stuck at the bottom, to prevent them from falling off the stand. I doubt the stand is causing the null.


----------



## Brad Horstkotte

I'm pretty sure that the recommendation for placing the batts above was just to test where placement would be most effective. For the actual installation, you'd want to unwrap the batts, not so much to remove the plastic, but to uncompress the batts from the packaging, and get the most volume for your money.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9270#post_22736025
> 
> 
> For your info, my room is fully brick-concrete, which is a reflection nightmare for many audiophile. I know many people have good result after adding bass traps (6" of OC703) but their rooms are NOT made of bricks, just plain wood frame and board instead. Therefore, I would like to know the effectiveness of bass trap in a room like mine...maybe I need 12" of bass trap to be effective?
> 
> Will denser material work better? Will RHT100 or RHT150 be more effective?
> 
> Is it OK to leave the Roxul batt plastic wrapping on for bass trap?
> 
> Speakers have BluTack stuck at the bottom, to prevent them from falling off the stand. I doubt the stand is causing the null.



Regardless of the room construction, an absorber will be equally effective in a room with any boundary. The difference is you will have longer modal resonances, which would take a larger quantity of absorbers, but not necessarily thickness. A 6" absorber goes as low as a 6" absorber regardless of the room conditions, if that makes sense. With that said, depending on where the problem frequency is, you may need them thicker than 6". For example if you're trying to absorb 40 Hz, many 6" absorbers will get you some small gains, but likely not what you need. If you need to absorb 70 Hz though, they would work great straddling a corner.


Denser material works well for thin traps, but I wouldn't consider anything greater than Roxul 80 (even 60 would be fine) for thicker traps. Once you get to a foot or so thick, standard fluffy insulation works best. So, the thicker it is, the lighter you want it to be. But to be specific, "density" isn't the important factor here, but "gas flow resistance". Though for most of these products, lighter density means less gas flow resistance.


Don't leave the Roxul in the plastic bags as they are extremely compressed in the bags. You can wrap them afterwards with thin plastic though if you are concerned. They will not lose bass efficiency.


You would be surprised at the amount of damage speakers being coupled to the floor can make - specifically, nulls. Proper decoupling is important! I'm not suggesting that IS what is happening, but it is certainly possible.


----------



## Skylinestar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9270#post_22742363
> 
> 
> Regardless of the room construction, an absorber will be equally effective in a room with any boundary. The difference is you will have longer modal resonances, which would take a larger quantity of absorbers, but not necessarily thickness. A 6" absorber goes as low as a 6" absorber regardless of the room conditions, if that makes sense. With that said, depending on where the problem frequency is, you may need them thicker than 6". For example if you're trying to absorb 40 Hz, many 6" absorbers will get you some small gains, but likely not what you need. If you need to absorb 70 Hz though, they would work great straddling a corner.
> 
> Denser material works well for thin traps, but I wouldn't consider anything greater than Roxul 80 (even 60 would be fine) for thicker traps. Once you get to a foot or so thick, standard fluffy insulation works best. So, the thicker it is, the lighter you want it to be. But to be specific, "density" isn't the important factor here, but "gas flow resistance". Though for most of these products, lighter density means less gas flow resistance.
> 
> Don't leave the Roxul in the plastic bags as they are extremely compressed in the bags. You can wrap them afterwards with thin plastic though if you are concerned. They will not lose bass efficiency.
> 
> You would be surprised at the amount of damage speakers being coupled to the floor can make - specifically, nulls. Proper decoupling is important! I'm not suggesting that IS what is happening, but it is certainly possible.


Thanks for the info.


I'm thinking of placing 2 stacks of RHT80 bass traps (4' x 2' x 1' each) horizontally behind my entertainment center...wondering if it's too tick?


----------



## GIK Acoustics

I would think that making an extra 1/3 the traps by making them 8" thick would be more beneficial for most rooms. Hitting as much corner area as possible will help again to absorb the most bass to balance out the room most. Don't forget that there are 12 possible corners - not only 4!


----------



## Mr Rogers AK

This is my first attempt at a HT and realized I have some acoustic problems. The bass is full/boomy around the room then drops off to nothing in the middle of the room. I’m sure I have other problems but the bass is the first to jump out at me. Any help with placement for bass traps and panels (plus size/thickness/quantity) in my room would much appreciated.


Here is some information that might help about my room size and setup.


Room size 18x13x10 notes: The vaulted ceiling is different in the front of the room vs. the back. The white doors are butted up to the back corner. Carpet is mid shag with thick DuPont pad. Two rows of seating and minimal placement options for the Sub (corner placement).

 

 


Audio setup: Denon AVR-3313CI, Klipsch RF-62II front, RC-52II center, RS-42II surround, SW-112 powered subwoofer. Changes I made after running the Audyssey setup (8 positions): all speakers changed to small, sub – yes LFE 80Hz raised 5db, crossover 80Hz.


Again thanks in advance for your help!!!


----------



## GIK Acoustics

Mr Rogers,


Bass will always drop off / cancel in the center of the room, no matter the acoustic treatment. The only way to change that is to alter your room dimensions (and it will still do it in the center of the new ones, etc) so you should always be sitting in the back half of the room, at least a foot or two from the center of the room.


The boominess you described is typical of an untreated room. The basics to cover would be your first reflection points from your mains/LCRs along with thick trapping in the corners of the room. A set up like this would be preferred: http://gikacoustics.com/acoustic-advice/ (this is a studio and not a home theater, but the same principals apply)


----------



## Roger Dressler




> Quote:
> Originally Posted by *Mr Rogers AK*  /t/255432/acoustical-treatments-master-thread/9270#post_22753928
> 
> 
> The bass is full/boomy around the room then drops off to nothing in the middle of the room. I’m sure I have other problems but the bass is the first to jump out at me. Any help with placement for bass traps and panels (plus size/thickness/quantity) in my room would much appreciated.


I had that same problem. The most effective remedy is to add another sub, with the two of them placed on opposing mid-walls (as a start). This will help cross-cancel the nodes that are killing the bass in the seating area. This technique is based on research from Harman (Welti) if you care to get into more of the physics.


----------



## pepar




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9270#post_22754791
> 
> 
> I had that same problem. The most effective remedy is to add another sub, with the two of them placed on opposing mid-walls (as a start). This will help cross-cancel the nodes that are killing the bass in the seating area. This technique is based on research from Harman (Welti) if you care to get into more of the physics.



This is most effective in rooms that are closed and rectangular.


Jeff


----------



## HaroldKumar

I solved a nagging null problem by hoisting one of my subs up to the ceiling. Since I have 10 ft ceilings there's lots of room up there.


----------



## mtbdudex

Here s a good tutorial for multiple sub placement, http://mehlau.net/audio/multisub_geddes/


----------



## pepar




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9270#post_22758635
> 
> 
> I solved a nagging null problem by hoisting one of my subs up to the ceiling. Since I have 10 ft ceilings there's lots of room up there.



We tend to think two-dimensionally when placing subs. But YES! I thing Geddes or Welti advocates raising subs ...


----------



## Mr Rogers AK

Thanks for the info everyone! So it looks like adding another sub and some acoustic treatment will help. Does anyone have any suggestions on how I can treat (bass trap) the corner by the white doors. I don’t think my wife will go for not being able to open both doors.


----------



## mtbdudex




> Quote:
> Originally Posted by *Mr Rogers AK*  /t/255432/acoustical-treatments-master-thread/9270#post_22761151
> 
> 
> Does anyone have any suggestions on how I can treat (bass trap) the corner by the white doors. I don’t think my wife will go for not being able to open both doors.



sure, here you go:

I'd suggest you make movable non-wall attaching corner bass traps.

Eric took my concept and applied it with pink fluffy, so this is my recommendation to you, a win-win with your wife.

He gives step-by-step instructions for you to follow.
http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/120#post_22131618 


> Quote:
> Originally Posted by *Eric2000*  /t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames/120#post_22131618
> 
> 
> I followed a similar construction technique that Mike posted for his corner bass traps, but made mine from pink fluffy R-19 instead and wrapped the fabric around the outside of the threaded rod. Here is the photo journey:
> 
> 
> My traps are 24x24x34 inch triangles, are about 3.5 feet tall, and probably weigh less than 10lbs each. Since I need access to one of the corners for a doorway, I made them stackable and moveable. I started by cutting triangles, drilling holes for the threaded rod, and inserting T-Nuts for the sides that stack on one another:
> 
> 
> 
> Then I cut 23" squares of insulation, cut them diagonally for triangles, and clipped off the corners so they fit snugly between the threaded rods:
> 
> 
> 
> A wire mesh made from separated Cat5 wire goes between each layer to keep the insulation from sagging over time. The numbered arrows indicate the direction of winding the wire to support the insulation. A bead of solder keeps the wire from unwinding. Each layer of insulation is about 5" thick.
> 
> 
> 
> Here is the first one all stacked up. You can see the supportive wire mesh wrapped around the threaded rod on each side:
> 
> 
> 
> And then with the Kraft paper glued to the front with spray adhesive:
> 
> 
> 
> Then, turn the trap upside down to affix the cloth wrapping - a two-pack of curtains from the giant W for $15. Each pack is enough for two traps.
> 
> 
> 
> The cloth is stapled to the underside of the top plate to prevent sagging over time:
> 
> 
> 
> When the fabric is fully secured to the top panel, turn the trap right side up again and pull the fabric around to the back. Trim off the excess and then just pull it tight and use a desk stapler to hold the fabric together in the back:
> 
> 
> 
> The staples produce a few ripples in the sides, but you won't see those once you put it in the corner. The front looks nice and clean:
> 
> 
> 
> Here is a closer shot of two of them stacked together:
> 
> 
> 
> And finally, the entire back half of the theater. With a few bean bag chairs up front, we can comfortably seat 10-12 people. The colors are a little off from a combination of CFL and flash lighting:
> 
> 
> 
> Below are the before and after REW plots. The purple trace is the original measurement with no traps and no EQ. The yellow trace is the difference made by the bass traps alone. The traps took 5dB off of the room-induced peak at 45Hz without sacrificing anything else in the audible range:
> 
> 
> 
> This is the original waterfall plot made by REW - no traps, no other corrections - just a mess with room modes at 45Hz and 90Hz:
> 
> 
> 
> And here is the waterfall plot after ONLY the traps are put in place. I was surprised by how much of a difference the traps made in the decay:
> 
> 
> 
> After several days of tweaking the parametric equalizer with the traps in place and a first order high-pass filter in place, here is my "final" room response curve - flat from 7Hz to 100Hz, plus/minus 3dB :'( The peak at 105Hz won't ever really happen because the preamp crosses the LFE channel at 60Hz.
> 
> 
> 
> And the "final" waterfall plot - nice and smooth. If I adjust the waterfall graphing limits in REW, the entire response curve is down by 20dB within the first 100-120ms with the exception of a 2-3dB narrow bump at about 23Hz. I am really pleased with this result:
> 
> 
> 
> It sounds great! The EQ and high-pass filter reduce (but don't eliminate) the incidence of amp clipping, but still provide enough punch to cause visitors to literally jump up from the couch
> 
> 
> All of my other projects are on my web page, which I think is linked in my signature.
> 
> 
> Eric


----------



## MSutton

Is the db-4-walls product in anyway acceptable for acoustical treatments? It's a dense rubber material that coats the walls for sound blocking.


Saw it recently at Lowes:

http://www.lowes.com/pd_336263-11580-DB-4-WALLS_0__?productId=3295396 
http://db-4-walls.com/


----------



## Roger Dressler

^^ Looks to me like the EQ had more significant effect than the traps. I wonder how those plots would look with EQ applied but without the traps (and with another notch thrown in for the 90-100 Hz peak).


As for the db4 Walls, they claim 75% noise reduction. I'd say that translates to 12 dB attenuation, but at unspecified frequencies. As a comparison, MLV (mass loaded vinyl), 1/8" thick (1 lb/sqft), has an STC of 26. That would appear to be much better, but I have no way to compare these apples to those oranges.


----------



## Dennis Erskine

I'm a sceptic (in re: db4). The manufacturer is making wild claims (75% 'unwanted' noise reduction) with absolutely nothing to back that claim up. For example, no accredited third party lab test results. It's a 1/4" thick product that Ms. Cutie can easily hold in place with two fingers (little mass), and costs $125 per sheet. Wow! It cannot be an absorber (1/4" and painted). Diaphragmatic? Nope. No weight given in any of the specifications. I suspect it is less effective than a second layer of drywall (or a second layer plus green glue) and far, far more expensive.


Here's a rule to follow: if a product claims acoustic or sound isolation benefits and the manufacturer cannot, or will not, supply third party test results, stay away. Also, for this type of application you are absolutely not interested in an STC value. You want to see the TL (transmission loss) values (which had to be obtained by the lab to come up with an STC).


----------



## rthompson10

I have in- wall speakers( floor standing sub) and my screen is mounted 3-4" off of the wall. Can I, should I treat the front wall? Will putting a treatment behind the screen but not the rest of the front wall do any good?


Thanks RT


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9300#post_22772084
> 
> 
> I'm a sceptic (in re: db4). The manufacturer is making wild claims (75% 'unwanted' noise reduction) with absolutely nothing to back that claim up. For example, no accredited third party lab test results. It's a 1/4" thick product that Ms. Cutie can easily hold in place with two fingers (little mass), and costs $125 per sheet. Wow! It cannot be an absorber (1/4" and painted). Diaphragmatic? Nope. No weight given in any of the specifications. I suspect it is less effective than a second layer of drywall (or a second layer plus green glue) and far, far more expensive.
> 
> Here's a rule to follow: if a product claims acoustic or sound isolation benefits and the manufacturer cannot, or will not, supply third party test results, stay away. Also, for this type of application you are absolutely not interested in an STC value. You want to see the TL (transmission loss) values (which had to be obtained by the lab to come up with an STC).



Holy cow, +1! Very well said Dennis.


I'm very skeptical of most products that don't provide test results. This is my feeling regardless if we're talking decoupling mechanisms, assemblies, absorbers, etc.


----------



## bananamane

Thought Id post this here instead of starting my own thread. I want to get some panels for my basement theater area. It has drop ceiling, carpet with thick padding, and drywall. Ive attached a rough picture of it from paint. I was thinking of putting two 2x2 panels from atsacoustics.com along the left wall and one 2x4 panels on the back wall above the couch. Would this likely help a lot? There currently isnt anything on the walls and I notice an echo so I was thinking panels would help.


----------



## spike9876

FYI,


I have a closet that seems to have a thin drywall... and I get noise from my neighbor.


Since its a closet, I doesn't need to look nice.


I have been checking Green Glue from soundproof company and SheetBlok Sound Isolation Barrier from Auralex. I was thinking about Sheetblok from Auralex... by just applying this on top of my drywall...


Any suggestions on the simplest way to soundproof my closet.


Thanks in advance.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *bananamane*  /t/255432/acoustical-treatments-master-thread/9300#post_22813217
> 
> 
> Thought Id post this here instead of starting my own thread. I want to get some panels for my basement theater area. It has drop ceiling, carpet with thick padding, and drywall. Ive attached a rough picture of it from paint. I was thinking of putting two 2x2 panels from atsacoustics.com along the left wall and one 2x4 panels on the back wall above the couch. Would this likely help a lot? There currently isnt anything on the walls and I notice an echo so I was thinking panels would help.



It would help somewhat, but 16 sq foot of absorption isn't really much, especially in a room that large. Anything is a start, but I would really recommend at least doubling that.


----------



## bananamane




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9300#post_22818359
> 
> 
> It would help somewhat, but 16 sq foot of absorption isn't really much, especially in a room that large. Anything is a start, but I would really recommend at least doubling that.



Thanks for the reply. Would I be alot better off getting two 2x4's for the side wall instead of the 2x2's? I was trying to make it aesthetically appealing as I could since the wife didnt really want any at all. So I know the side wall and back wall would be the only places I could put them, just wondering if its worth it. Most likely the other walls will never get anything. Its not a theater just a family room type thing with projector and stuff.


----------



## Torqdog

Hi all, I'm new to this forum and I have some questions as to how to effectively deal with my 24' x 24' room with a 10' ceiling. Everything I've read seems to indicate that a room of this dimension is a real problem and I guess that it's probably compounded by the fact that the seating is somewhat close to the middle(no choice, wife rules! LOL).


Do any of you have experience with a similar sized room or do you know of a link where I could get some info specific to my situation?


----------



## phisch

I am getting ready to do the acoustic treatments for the front wall of my theater that is currently under construction. My plan is to use Linacoustic acoustablanket for the front wall behind the speakers, and OC703 wedges in the corners for bass traps. My question is what is the recommended thickness for the Linacoustic I should be using? I've seen people in the theater construction threads use anywhere from 1" to 2", but I'm not sure which is correct.


Thanks


----------



## GIK Acoustics




> Quote:
> Originally Posted by *bananamane*  /t/255432/acoustical-treatments-master-thread/9300#post_22819704
> 
> 
> Thanks for the reply. Would I be alot better off getting two 2x4's for the side wall instead of the 2x2's? I was trying to make it aesthetically appealing as I could since the wife didnt really want any at all. So I know the side wall and back wall would be the only places I could put them, just wondering if its worth it. Most likely the other walls will never get anything. Its not a theater just a family room type thing with projector and stuff.



More absorption would definitely be worth it. You could always go with four 2x2s instead of two 2x4s.


We definitely understand the importance of what we call WAF (wife approval factor). Have you checked into things like custom Art Panels or nicer fabrics like the Guilford of Maine line? You can see examples of custom Art Panels here: http://gikacoustics.com/product/gik-artpanel-acoustic-panels/ and check out Guilford of Maine's colors here: http://gikacoustics.com/product/color-swatch-book/ (they also have EXCELLENT very high res photos of their fabrics on their website)



> Quote:
> Originally Posted by *Torqdog*  /t/255432/acoustical-treatments-master-thread/9300#post_22820215
> 
> 
> Hi all, I'm new to this forum and I have some questions as to how to effectively deal with my 24' x 24' room with a 10' ceiling. Everything I've read seems to indicate that a room of this dimension is a real problem and I guess that it's probably compounded by the fact that the seating is somewhat close to the middle(no choice, wife rules! LOL).
> 
> 
> Do any of you have experience with a similar sized room or do you know of a link where I could get some info specific to my situation?



The dimensions would certainly cause some large bass response problems, though treatment would be similar regardless of the room. The only difference is you'll likely need stronger bass treatments (so corner traps, like soffit or tritraps/superchunks would be highly beneficial). Luckily though, the room is good size, so things like diffusion can easily be used for a good benefit.


Close to middle doesn't necessarily mean middle. How close are you to the middle? The bass nulls caused by the middle of the room will NOT change regardless of treatment. The only thing that can change nulls due to position are moving, or changing the dimensions of the wall. Do you have a drawing of your room?



> Quote:
> Originally Posted by *phisch*  /t/255432/acoustical-treatments-master-thread/9300#post_22827518
> 
> 
> I am getting ready to do the acoustic treatments for the front wall of my theater that is currently under construction. My plan is to use Linacoustic acoustablanket for the front wall behind the speakers, and OC703 wedges in the corners for bass traps. My question is what is the recommended thickness for the Linacoustic I should be using? I've seen people in the theater construction threads use anywhere from 1" to 2", but I'm not sure which is correct.
> 
> 
> Thanks



Thicker is better for absorbing lower frequencies. At roughly 800 Hz and above, they will both perform identically, but a 2" thickness will result in much more low end absorption. If bass absorption is needed, go with 2".


----------



## phisch




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9300#post_22827633
> 
> 
> Thicker is better for absorbing lower frequencies. At roughly 800 Hz and above, they will both perform identically, but a 2" thickness will result in much more low end absorption. If bass absorption is needed, go with 2".



That makes sense, thank you for the quick answer.


----------



## Cloggerdude

Made a thread with some questions about acoustic treatments for my home theater room:

http://www.avsforum.com/t/1451756/help-with-acoustical-treatment-in-my-home-theater 


If any of you guys had any suggestions or anything, I would really appreciate it.


----------



## Torqdog




> Quote:
> Originally Posted by *GIK Acoustics*
> 
> The dimensions would certainly cause some large bass response problems, though treatment would be similar regardless of the room. The only difference is you'll likely need stronger bass treatments (so corner traps, like soffit or tritraps/superchunks would be highly beneficial). Luckily though, the room is good size, so things like diffusion can easily be used for a good benefit.
> 
> 
> Close to middle doesn't necessarily mean middle. How close are you to the middle? The bass nulls caused by the middle of the room will NOT change regardless of treatment. The only thing that can change nulls due to position are moving, or changing the dimensions of the wall. Do you have a drawing of your room?


Thanks for the response. The seating is positioned about 14' from the front wall and about 9.5' from the back, centered side to side. The front monitors are about 32" out from the front wall, side monitors about 1.5' out and the rear monitors are mounted to built in suspended shelving that hangs down from the cieling 30" and lines the back wall. The room itself is a detached garage that kind of doubles as a light duty workshop/theater with the theater aspect taking up most of the room and the workshop aspect relegated to the back wall with a workbench and pegboard for my tools as well as items like a Gun safe, small refridgerator/wine fridge on top of that and various tools like a table saw etc in the corner, again, all against the back wall. I'd supply you with a diagram but am not able to do that.


1st reflections don't seem too bad but I think I could definitely benefit with something on the ceiling. I've thought about Bass traps

but am not quite sure how to go about that on a DIY basis. I have access to some interesting material.......2" thick, dense foam with a unique thick fabric layer on one side that might aid in sound diffusion. It came from a Gym and was used as a floor mat for excersize. I'm not sure if it wouldn't be a bit of overkill but it might work well for doing some sort of DIY Bass trap.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Torqdog*  /t/255432/acoustical-treatments-master-thread/9300#post_22844634
> 
> 
> 1st reflections don't seem too bad but I think I could definitely benefit with something on the ceiling.



Yes - you likely don't hear too much of a damaging effect from reflections since your room is 24' wide, but IMO if your speakers are still relatively close to a wall (within 2 meters) you will still likely experience some phasing type issues from reflections. The ceiling is, as you've pointed out, a bit bigger of an issue as it isn't nearly as tall.


> Quote:
> Originally Posted by *Torqdog*  /t/255432/acoustical-treatments-master-thread/9300#post_22844634
> 
> 
> I've thought about Bass traps
> 
> but am not quite sure how to go about that on a DIY basis. I have access to some interesting material.......2" thick, dense foam with a unique thick fabric layer on one side that might aid in sound diffusion. It came from a Gym and was used as a floor mat for excersize. I'm not sure if it wouldn't be a bit of overkill but it might work well for doing some sort of DIY Bass trap.



There are a few threads here on building them. Superchunks offer good performance while taking up not as important of floor space (they go in the corners of the room)


Not sure about the material you've suggested though, its likely a very poor performer. Unfortunately, densities and a materials ability to compress really don't have too much to do with their absorbing qualities.


----------



## Torqdog




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9300#post_22848939
> 
> 
> Yes - you likely don't hear too much of a damaging effect from reflections since your room is 24' wide, but IMO if your speakers are still relatively close to a wall (within 2 meters) you will still likely experience some phasing type issues from reflections. The ceiling is, as you've pointed out, a bit bigger of an issue as it isn't nearly as tall.
> 
> There are a few threads here on building them. Superchunks offer good performance while taking up not as important of floor space (they go in the corners of the room)
> 
> 
> Not sure about the material you've suggested though, its likely a very poor performer. Unfortunately, densities and a materials ability to compress really don't have too much to do with their absorbing qualities.


Thanks. It sounds as though my room might not be as difficult to tame as I have been led to believe. I will seek out those forums you mentioned and continue my edumacation quest.


----------



## dholmes54

Im having trouble hearing my center ch during movies & was wondering if ceiling treatments would help,Im getting old cant hear as well as I use to! My ceiling is painted OSD board,Ive got treatments in the room (side wall & bass trap treatments) would ceiling treatments help above LCR spks? thanks


----------



## dynfan

I have a diffusion question for anyone with real world experience. Is there a minimum depth that we should be considering when buying or constructing diffusors? I am experimenting with diffusion in the back of my audio room and have several ideas floating around in my head...


1. I have a bunch of Auralex Mini Fusors that are 12" x 12" panels and roughly 6" in depth for the diffusor itself. The plan was to fill the cavity with OC703 and place them in array at the locations I have proposed.


2. I have seen other auralex products that are only 1" or 2" thick that are labeled as diffusors and have considered using them for ceiling reflection points or perhaps in place of the deeper mini fusors so they protrude in to the room less. I am not SET on using these products and am willing to fabricate or duplicate them on my own.


3. I have been browsing home improvement stores for items that can be used in place of commercial products. I have found some rigid fiberboard panels that is sold in 4' x 8' sheets and is in the form of a waveform. The difference between the high and low points is about 2" and I was considering cutting this material and placing it behind a fabric frame to allow the treatments to better blend in the room.


My question is really one of how effective can a diffusor be based on depth of the device and based on that answer are different depths better suited to use in different areas. i.e. ceiling versus rear wall...



Thanks in advance!


----------



## SeaNile

I've never had any type of acoustical treatments in any stereo or HT system I have ever had. Guess it would be a wise thing to have a few treatments before spending thousands on new components, subs, speakers, etc.


This is a general use room so I can't go insane with treatments, etc. Ceilings are 9', 24' wide and about 30-33' long. Lots of hard surfaces, pictures on wall, drywall, etc. Other than the curtains that I put down whenever watching or listening to the system the room has no treatments.


Suggestions welcome!


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Torqdog*  /t/255432/acoustical-treatments-master-thread/9300#post_22850429
> 
> 
> Thanks. It sounds as though my room might not be as difficult to tame as I have been led to believe. I will seek out those forums you mentioned and continue my edumacation quest.



Yes, it is certainly not an impossible feat. Get to it!


----------



## GIK Acoustics




> Quote:
> Originally Posted by *dholmes54*  /t/255432/acoustical-treatments-master-thread/9300#post_22850468
> 
> 
> Im having trouble hearing my center ch during movies & was wondering if ceiling treatments would help,Im getting old cant hear as well as I use to! My ceiling is painted OSD board,Ive got treatments in the room (side wall & bass trap treatments) would ceiling treatments help above LCR spks? thanks



This will likely give an improvement if reflections from the ceiling are causing the problem, but it could just be the center channel as well. I would try different placements of your center channel to see if it changes anything and to make sure it isn't defective.


Something else to look into as well are floor reflections - if you have a hard floor, you might consider using a rug on the first reflection point on the ground.


With all that being said - first reflections on the ceiling are harmful and treating them is suggested. I just would rather not tell you it is the problem as it could be a few different things.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *dynfan*  /t/255432/acoustical-treatments-master-thread/9300#post_22850750
> 
> 
> I have a diffusion question for anyone with real world experience. Is there a minimum depth that we should be considering when buying or constructing diffusors? I am experimenting with diffusion in the back of my audio room and have several ideas floating around in my head...



Yes! Depth of the diffusor will determine how low in frequency it diffuses to (but this also requires being farther away from it to gain the benefits). Likewise, the width of the wells will determine the high frequency cut-off of the diffusor.


> Quote:
> Originally Posted by *dynfan*  /t/255432/acoustical-treatments-master-thread/9300#post_22850750
> 
> 
> 1. I have a bunch of Auralex Mini Fusors that are 12" x 12" panels and roughly 6" in depth for the diffusor itself. The plan was to fill the cavity with OC703 and place them in array at the locations I have proposed.



I don't work for Auralex, but I'm quite sure I can confidently say yes - filling the cavity behind the T-Fusors with fiberglass will result in some low-mid to mid frequency absorption. It won't necessarily enhance the performance of the diffusors though (as in, it won't change the working frequencies of them)


> Quote:
> Originally Posted by *dynfan*  /t/255432/acoustical-treatments-master-thread/9300#post_22850750
> 
> 
> 2. I have seen other auralex products that are only 1" or 2" thick that are labeled as diffusors and have considered using them for ceiling reflection points or perhaps in place of the deeper mini fusors so they protrude in to the room less. I am not SET on using these products and am willing to fabricate or duplicate them on my own.



The only product Auralex makes (that I'm aware of) labelled as a diffusor at a thin depth is the MetroFusor. It is slim at 2" of depth. While the product does work (I don't want to say that the product is a sham, as it isn't) it is VERY limited by the size. As I've stated above, depth of the diffusor determines how low the diffusor works. Diffusors 2" or thinner will not give you any considerable diffusion for anything other than very high frequencies. Building your own or purchasing MUCH thicker diffusors would be _much_ more beneficial IMO.


> Quote:
> Originally Posted by *dynfan*  /t/255432/acoustical-treatments-master-thread/9300#post_22850750
> 
> 
> 3. I have been browsing home improvement stores for items that can be used in place of commercial products. I have found some rigid fiberboard panels that is sold in 4' x 8' sheets and is in the form of a waveform. The difference between the high and low points is about 2" and I was considering cutting this material and placing it behind a fabric frame to allow the treatments to better blend in the room.



Could you find a link to a similar product? I've never seen something like this sold in stores. Concave and convex shapes such as these are typically bad though, as they focus sound and typically don't offer great spacial diffusion.


> Quote:
> Originally Posted by *dynfan*  /t/255432/acoustical-treatments-master-thread/9300#post_22850750
> 
> 
> My question is really one of how effective can a diffusor be based on depth of the device and based on that answer are different depths better suited to use in different



Different depths are more beneficial in different places. To be general, you can be closer to a diffusor that only diffuses high frequencies than you can to a diffusor that diffuses mid and hi-mid frequencies. You usually don't want to be within a few feet of a wide performing diffusor.


----------



## dholmes54

Thanks GIK acoustics guy,my LRC spks are JTR triple 12s so my spks are pretty good!


----------



## pepar

The wood blocks in this appear to be 4x4 or 6x6. For some reason, mounting method perhaps - or by design, there are spaces between the blocks. Would those spaces enhance, decrease or have no effect at all on the diffusion properties?


----------



## GIK Acoustics

That roofing design doesn't look to be calculated diffusion (it would be much too low in frequency to be useful at that distance and for that purpose in either case). It just seems to be an attractive ceiling with wood mounted at random depths. This will help scatter sound and will clean up the acoustics of a space like this, but wouldn't be of much benefit in a room where we need predictable and accurate results.


Also, the spaces between the wood will increase absorption a large amount which is something you typically want to avoid with diffusion. A good diffusor will diffuse as evenly as possible with as little absorption as possible.


More on diffusion here: http://gikacoustics.com/how-diffusion-works/


----------



## pepar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9300#post_22863829
> 
> 
> That roofing design doesn't look to be calculated diffusion (it would be much too low in frequency to be useful at that distance and for that purpose in either case). It just seems to be an attractive ceiling with wood mounted at random depths. This will help scatter sound and will clean up the acoustics of a space like this, but wouldn't be of much benefit in a room where we need predictable and accurate results.
> 
> 
> Also, the spaces between the wood will increase absorption a large amount which is something you typically want to avoid with diffusion. A good diffusor will diffuse as evenly as possible with as little absorption as possible.



Thanks. I suppose with a large hard-surfaced space, absorption is important for creating an environment where conversation is easy and one doesn't have to raise one's voice to be heard.


So, calculating block lengths for 4x4, 6x6 and larger, where the ceiling is this high ... is useless for diffusion?


Jeff


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9300#post_22864219
> 
> 
> So, calculating block lengths for 4x4, 6x6 and larger, where the ceiling is this high ... is useless for diffusion?
> 
> 
> Jeff



It seems I should have been a bit more clear. If they were 6x6 blocks, these would diffuse ONLY quite low frequencies compared to a normal diffusor - and would need a LOT of space to work properly. Though, I didn't realize how high the ceiling is - I'm still (perhaps incorrectly) assuming you need to be further than that distance to get notable and useful diffusion. Also, calculating a grid this large would likely take insane amounts of time (though it isn't really clear how large of a grid this uses). You might want to hire a computational mathematician like my girlfriend to come up with methods to ease the calculation. This is the main reason I believe this isn't calculated and looks to be random. Which really is fine for the purpose, as it doesn't need to evenly diffuse at all, it mostly needs to absorb (which is what it's doing with the air spaces between the wood). Random still helps with scattering reflections and the spaces give good absorption, creating an easier conversational area, but doesn't equally diffuse sound and would not be very helpful in an environment other than where its at. Its better than a flat wall, yes, but to what extent would be quite difficult, if not impossible to know.


Edit: Its diffusion properties, if correctly calculated, would likely be akin to carpet's absorption properties. It is a good absorber but only at particular frequencies, and is a poor absorber otherwise. I'm assuming the same would be true of the diffusive properties of that ceiling.


----------



## pepar

So, then it is likely only aesthetic and "green" .. it is reclaimed wood ... and it absorbs.


Thanks for your insights.


Jeff


----------



## angryht

I have a question regarding ceiling treatments. I believe that I'm getting quite a bit of reflection from the ceiling from the center speaker. I have some 1" thick linacoustic and my plan was to build a frame 4' by 4' (out of 1" x 2" furring strips) and stretch some black ponte fabric (speaker grill fabric) over it. Then I was going to set the 1" linacoustic in the frame and hang it from the ceiling using hooks and eyes. I would not be covering the entire ceiling just the sections as determined by the mirror test. Does this make sense? I realize the ponte is not fire resistant but I would not be covering an entire wall or ceiling and there are not any lights on the ceiling, just wall sconces.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9300#post_22864381
> 
> 
> So, then it is likely only aesthetic and "green" .. it is reclaimed wood ... and it absorbs.
> 
> 
> Thanks for your insights.
> 
> 
> Jeff



Seems to be, yes. A great cause _and_ effect!


> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9300#post_22864917
> 
> 
> I have a question regarding ceiling treatments. I believe that I'm getting quite a bit of reflection from the ceiling from the center speaker. I have some 1" thick linacoustic and my plan was to build a frame 4' by 4' (out of 1" x 2" furring strips) and stretch some black ponte fabric (speaker grill fabric) over it. Then I was going to set the 1" linacoustic in the frame and hang it from the ceiling using hooks and eyes. I would not be covering the entire ceiling just the sections as determined by the mirror test. Does this make sense? I realize the ponte is not fire resistant but I would not be covering an entire wall or ceiling and there are not any lights on the ceiling, just wall sconces.



Yep - that would do the trick!


Something to keep in mind: Even though a 48" x 48" piece of 1" thick Linacoustic isn't terribly heavy, your panel will likely sag a lot if you don't add any cross braces. Its almost impossible to stretch fabric tight enough on a 48" x 48" frame to hold it up. A brace down both directions in the center should be enough. Having that said, its probably possible to do without cross braces - but you'll likely get much better results with the cross braces.


Also, you could double up the Linacoustic so you have a 2" thin panel instead, which will absorb to a lower frequency. Hanging it down from the ceiling a couple inches will also help in the same retrospect.


----------



## wse




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9210#post_22677582
> 
> 
> 
> Do not place a subwoofer such that the driver is aimed into the seating locations (in a residential sized room). If you do, you should place a 1" thick piece of 1.5 PCF fiberglass in front of the driver. Sometimes it requires 2".
> 
> FOH...let's avoid this terminology. Perhaps better as where the x.x wave length is longer than the room dimension. There is too much misunderstanding about "bass not fitting into a room".


 

I placed my two subs in the middle of the side walls of my listening position as suggested by Toole!


----------



## wse


On an other not can I use my fireplace as a bass trap I never use it to much pollution


----------



## GIK Acoustics




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9330#post_22871545
> 
> 
> On an other not can I use my fireplace as a bass trap I never use it to much pollution



Of course you can, but there may be better places to trap in the room as well. Do you have your corners treated at all?


----------



## angryht




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9330#post_22870020
> 
> 
> Something to keep in mind: Even though a 48" x 48" piece of 1" thick Linacoustic isn't terribly heavy, your panel will likely sag a lot if you don't add any cross braces. Its almost impossible to stretch fabric tight enough on a 48" x 48" frame to hold it up. A brace down both directions in the center should be enough. Having that said, its probably possible to do without cross braces - but you'll likely get much better results with the cross braces.


You certainly got that right. I built the frame and stretched the fabric as tight as I could and stapled it to the opposite side as the frame. I even broke one of the sides and had to replace it. I was expecting a little sagging due to the weight of the linacoustic and I got some (about 1 inch in the middle). If I put in braces in the from the center of each side to the opposite side, I would still need to staple to the exposed side to gain any benefit from the bracing, right? That was what I was trying to avoid but maybe 4' by 4' is too large. I probably should have built 2' by 2' frames. Otherwise I would need to staple the fabric to the braces and maybe paint the exposed staples. I suppose I could use velcro to stick the underside of the fabric to the braces. Is that typical? That way I could double up the linacoustic and hang it about an inch from the ceiling as you suggested. I really appreciate your input!


----------



## GIK Acoustics




> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9330#post_22872406
> 
> 
> If I put in braces in the from the center of each side to the opposite side, I would still need to staple to the exposed side to gain any benefit from the bracing, right?



Well, this depends. If the sagging was from the fabric and you just weren't able to pull tight enough, then yes, you'd need to staple the side showing the room (or you might be able to use adhesive). But if the sag was due to the Linacoustic and NOT the fabric, then the cross brace would hold the Linacoustic up so the fabric wouldn't sag.


> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9330#post_22872406
> 
> 
> That was what I was trying to avoid but maybe 4' by 4' is too large. I probably should have built 2' by 2' frames.



24 x 48 frames still work quite well since one of the sides is 24". This means the whole thing will still be quite tight. I've even built some 4' x 8' traps that don't sag, but I didn't have the same problems as I built a fabric frame out of 1x2s that I inserted into the main 4' x 8' frame, which gave me a lot more freedom to mend the fabric around to get it tight.


> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9330#post_22872406
> 
> 
> Otherwise I would need to staple the fabric to the braces and maybe paint the exposed staples.



This is an option. Depending on how wide your cross braces are, you might be able to use spray adhesive. Just spray it on the bottom of the cross brace and along the path the crossbrace would meet on the fabric, insert it into the frame above the fabric (on a flat surface, obviously). You can add your Linacoustic in to give it a bit of weight to help the adhesive set.


> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9330#post_22872406
> 
> 
> Otherwise I would need to staple the fabric to the braces and maybe paint the exposed staples. I suppose I could use velcro to stick the underside of the fabric to the braces. Is that typical?



Not sure about it being "typical" but it might work. Not really the person to ask though, as I'm not an experienced user of velcro.


----------



## angryht




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9330#post_22873194
> 
> 
> Well, this depends. If the sagging was from the fabric and you just weren't able to pull tight enough, then yes, you'd need to staple the side showing the room (or you might be able to use adhesive). But if the sag was due to the Linacoustic and NOT the fabric, then the cross brace would hold the Linacoustic up so the fabric wouldn't sag.



Okay, forgive me for getting too far into the weeds on this one, and thank you for the help.


The fabric is pulled tight enough so that there is no sag when the Linacoustic is not being suspended by the frame/fabric. When the Linacoustic is placed on the fabric, there is a sag. So, I think what you are saying by 'if the sagging is from the fabric and you weren't able to pull tigh enough', is that the sag is from the fact that the fabric is not tight enough to prevent the sag. - Gosh, when I type it like that it seems intuitively obvious that is what you meant. And the reason that it is not as tight as it could be is because there is a lack of bracing which prevents pulling tight enough to get it even tighter. So, one option would be to remove the fabric, insert the cross braces and then reinstall the fabric tight enough (fingers crossed) that there is no sag. Otherwise, do you mean to put in the cross braces and have the Linacoustic to be placed over that part of the frame?


> Quote:
> 24 x 48 frames still work quite well since one of the sides is 24". This means the whole thing will still be quite tight. I've even built some 4' x 8' traps that don't sag, but I didn't have the same problems as I built a fabric frame out of 1x2s that I inserted into the main 4' x 8' frame, which gave me a lot more freedom to mend the fabric around to get it tight.



I'm not sure I understand this approach. Does that mean that you first built a frame 4' x 8' then made smaller fabric covered frames to fit inside them? Just trying to picture it.


----------



## GIK Acoustics

I think I understand what you're asking and I think you've got it, but let me clarify anyways.


The cross brace can be used in two ways: to hold the JM up and/or to hold the fabric up.


If the fabric doesn't sag without the JM, then insert the cross braces so it holds up the JM and it won't make your fabric sag.


If the fabric sags anyways, then you can affix the fabric to the cross braces by staples or adhesive, whatever you choose, and it will still provide support to hold up the insulation as well.


Edit: I should clarify that the cross braces need to be actually attached to the outer frame, not simply "sitting" in. I think this caused the confusion.



> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9330#post_22873564
> 
> 
> I'm not sure I understand this approach. Does that mean that you first built a frame 4' x 8' then made smaller fabric covered frames to fit inside them? Just trying to picture it.


I made one 4' x 8' frame (with crossbraces) that had the fabric wrapped around it, and that was inserted inside a slightly bigger than 4' x 8' frame. So yes, what you said is correct, only that it was one large inside frame instead of multiple smaller frames. Though, many small ones would also work in this circumstance.


A last option can be to use appearance grade finished wood or molding to do a 4 window frame. You could fix this to the outside of the frame/fabric which will hold both the JM and fabric up (and look pretty cool too, but obviously be more work and more cost)


----------



## angryht




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9330#post_22873872
> 
> 
> The cross brace can be used in two ways: to hold the JM up and/or to hold the fabric up.
> 
> 
> If the fabric doesn't sag without the JM, then insert the cross braces so it holds up the JM and it won't make your fabric sag.



Clarified! And quite well I might add.


> Quote:
> Edit: I should clarify that the cross braces need to be actually attached to the outer frame, not simply "sitting" in. I think this caused the confusion.
> 
> I made one 4' x 8' frame (with crossbraces) that had the fabric wrapped around it, and that was inserted inside a slightly bigger than 4' x 8' frame. So yes, what you said is correct, only that it was one large inside frame instead of multiple smaller frames. Though, many small ones would also work in this circumstance.



Got it.


> Quote:
> A last option can be to use appearance grade finished wood or molding to do a 4 window frame. You could fix this to the outside of the frame/fabric which will hold both the JM and fabric up (and look pretty cool too, but obviously be more work and more cost)


I like that idea to dress it up a bit. I have linacoustic on my walls and I've been meaning to cover it with fabric, but I haven't yet.


On another note: Previously, I had cut my Linacoustic RC (1" thick) into triangles and just set them (superchunk style - triangles stacked against each other) along the floor to wall corners and from floor to about 3 or 4 feet up. The triangles are about 10" by 10" by whatever the hypotenuse (~14"). I always thought that those would be somewhat effective bass traps but since they were not wrapped in fabric, I did not like them because they 'shed' fiberglass a lot. I have since removed them from the room and I am now wondering about wrapping them in fabric. Since the Linacoustic has very little stiffness, I imagine it that this would require a triangular frame on each end (thin plywood or even fur 1"x2" in a triangle) and some type of straight piece to attach the fabric to. Long story short, would it be more effective to double or even quadruple the 1" Linacoustic in a frame to straddle corner? I've seen that most people like to use the OC 700 Series for this because of the stiffness. I have looked at bobgolds.com to check the coefficients for the materials, just wondering about doubling them up and their effectiveness in bass trapping (the Linacoustic that is).


----------



## HaroldKumar

I thought I'd share my some build pictures of my N31+6 panel. Built with 3/16" gatorboard and hot glue. The cavities will be filled with OC703. Should be finished and installed tonight on the back wall! Hopefully will turn my little room into a concert hall.


----------



## Dennis Erskine

How many dozens of feet are there between this assembly on the back wall and the nearest listening position?


----------



## localhost127




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread/9330#post_22876788
> 
> 
> How many *dozens of feet* are there between this assembly on the back wall and the nearest listening position?



dozens?


with what looks to be approx 7" max well depth only requires approx ~4' 2" to be considered in far-field.


+/- error from the mkI eyeball.


----------



## localhost127




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9330#post_22875858
> 
> 
> I thought I'd share my some build pictures of my N31+6 panel. Built with 3/16" gatorboard and hot glue. The cavities will be filled with OC703. Should be finished and installed tonight on the back wall! Hopefully will turn my little room into a concert hall.



looking great! no need to fill the cavities with expensive oc703 - pink fluffy will do (cheaper and easier to stuff); just to limit resonance within the cavities.


make sure the wells/air-gaps/cracks are *fully sealed* to limit unwanted absorption!


----------



## HaroldKumar




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9330#post_22876905
> 
> 
> dozens?
> 
> 
> with what looks to be approx 7" max well depth only requires approx ~4' 2" to be considered in far-field.
> 
> 
> +/- error from the mkI eyeball.



Good eye! yes, 7" well depth, and you nailed the 4'2. here's the plan in QRDude:

 


Diffuse to 812 hz, scatter 406 hz. My seating postition is 6 feet.


My carpenter did an amazing job, all the depths are accurate and it's attractive. The black gator board works well. Very solid feeling, yet it's only 15 lbs if that. Cedar frame looks and smells good.










I will post some listening impressions soon.


Correction: weight is about 40 lbs.


----------



## localhost127

wicked.


HT or 2channel setup?


you could always bring the QRD out from the rear wall 1.5ft or so and construct a false wall from the QRD and make the rest of the rear wall (around and behind the QRD) a giant porous LF absorber filled with pink fluffy attic insulation for additional LF absorption.


----------



## HaroldKumar




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9330#post_22877439
> 
> 
> wicked.
> 
> 
> HT or 2channel setup?
> 
> 
> you could always bring the QRD out from the rear wall 1.5ft or so and construct a false wall from the QRD and make the rest of the rear wall (around and behind the QRD) a giant porous LF absorber filled with pink fluffy attic insulation for additional LF absorption.



It's HT, but using 50/50 music. Music is 2.1x3 using Oppo 105 analog outs. That's a good suggestion on the back wall but I don't want to give up that much space in an already small room and I'm eating up 2.5 feet of the front wall with AT screen. I am going to soon do a retractable so the screen is out of way for music listening. For bass traps I straddle 4" OC703 on corners where I can and also ceiling to walls. I'm going to be doing some tidying up and paint and spackle this weekend. After that I'll get some pictures.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9330#post_22874163
> 
> 
> On another note: Previously, I had cut my Linacoustic RC (1" thick) into triangles and just set them (superchunk style - triangles stacked against each other) along the floor to wall corners and from floor to about 3 or 4 feet up. The triangles are about 10" by 10" by whatever the hypotenuse (~14"). I always thought that those would be somewhat effective bass traps but since they were not wrapped in fabric, I did not like them because they 'shed' fiberglass a lot. I have since removed them from the room and I am now wondering about wrapping them in fabric. Since the Linacoustic has very little stiffness, I imagine it that this would require a triangular frame on each end (thin plywood or even fur 1"x2" in a triangle) and some type of straight piece to attach the fabric to. Long story short, would it be more effective to double or even quadruple the 1" Linacoustic in a frame to straddle corner? I've seen that most people like to use the OC 700 Series for this because of the stiffness. I have looked at bobgolds.com to check the coefficients for the materials, just wondering about doubling them up and their effectiveness in bass trapping (the Linacoustic that is).



Is your question: "Should I go with a 10" x 10" x ~14" super chunk vs. a 4" thick standard size absorber straddling the corner" ?


I'm not too sure honestly, I've never used a superchunk that sized before but it is quite small. I would think you will get similar results. If you already have the pieces cut into triangles, it seems the path of least resistance. Perhaps you can put the triangles back in, and build a standard 4" thick absorber, and just cover the triangles unwrapped with the standard panels? Just an idea.


The first absorber I ever built myself was made from four 1" thick sheets of JM to make a 4" thick 24x48" absorber. They worked good enough. I ripped the dark side (the "RC") off the panels when I quadrupled them up so the GFR wouldn't be changing every inch back and fourth. Not sure how they would perform otherwise (but I don't suspect them to be insanely different either way).


----------



## angryht




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9330#post_22878989
> 
> 
> Is your question: "Should I go with a 10" x 10" x ~14" super chunk vs. a 4" thick standard size absorber straddling the corner" ?



That's exactly what I am asking and it looks like you answered below. Thanks again.


> Quote:
> I'm not too sure honestly, I've never used a superchunk that sized before but it is quite small. I would think you will get similar results. If you already have the pieces cut into triangles, it seems the path of least resistance. Perhaps you can put the triangles back in, and build a standard 4" thick absorber, and just cover the triangles unwrapped with the standard panels? Just an idea.



That's a good idea. It seems like there are a lot of directions I could go and utilizing the triangles I already have cut covered with a larger panel absorber might just be the ticket.


> Quote:
> The first absorber I ever built myself was made from four 1" thick sheets of JM to make a 4" thick 24x48" absorber. They worked good enough. I ripped the dark side (the "RC") off the panels when I quadrupled them up so the GFR wouldn't be changing every inch back and fourth. Not sure how they would perform otherwise (but I don't suspect them to be insanely different either way).



Wow, you read my mind about the RC. I was wondering about removing the reinforced coating when doubling (or quadrupling) things up. Since I just doubled up, I ended up putting the RC on the outsides of the doubled up sandwich. I have always heard that the RC should be put towards the room side when placed on a wall so I thought having it on the outside was appropriate. If I go quadruple, I guess I'll take it off.


And speaking of building one's first panel. . . I finished mine and hung it. It’s 4’ by 4’ by 2” thick (doubled the linacoustic) and has a little over an inch gap between it and the ceiling. Thanks to your suggestion, I put in a couple cross braces to remove the sag in the fabric due to the weight of the Linacoustic and it worked like a charm. Mounted it so it’s rotated 45 degrees from the outside walls (askew) to cover more of the reflective area as determined by the mirror method, and because the kids said it would look cool. It’s big and I love the look.


A few pics:

 

 

 


Thank you again for your help.


Now that I'm getting the hang of this fabric stretching, it's time to look for some fire rated material for my walls.


----------



## GIK Acoustics

Kudos - great work!


----------



## angryht

Thanks.


----------



## dynfan




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9300#post_22861456
> 
> 
> Yes! Depth of the diffusor will determine how low in frequency it diffuses to (but this also requires being farther away from it to gain the benefits). Likewise, the width of the wells will determine the high frequency cut-off of the diffusor.
> 
> I don't work for Auralex, but I'm quite sure I can confidently say yes - filling the cavity behind the T-Fusors with fiberglass will result in some low-mid to mid frequency absorption. It won't necessarily enhance the performance of the diffusors though (as in, it won't change the working frequencies of them)
> 
> The only product Auralex makes (that I'm aware of) labelled as a diffusor at a thin depth is the MetroFusor. It is slim at 2" of depth. While the product does work (I don't want to say that the product is a sham, as it isn't) it is VERY limited by the size. As I've stated above, depth of the diffusor determines how low the diffusor works. Diffusors 2" or thinner will not give you any considerable diffusion for anything other than very high frequencies. Building your own or purchasing MUCH thicker diffusors would be _much_ more beneficial IMO.
> 
> Could you find a link to a similar product? I've never seen something like this sold in stores. Concave and convex shapes such as these are typically bad though, as they focus sound and typically don't offer great spacial diffusion.
> 
> Different depths are more beneficial in different places. To be general, you can be closer to a diffusor that only diffuses high frequencies than you can to a diffusor that diffuses mid and hi-mid frequencies. You usually don't want to be within a few feet of a wide performing diffusor.



I really appreciate the in depth response and it certainly helps. I also watched all of the video's on your site regarding diffusion and placement. My room design started with similar ideals to what you have on your site so the start is good. Front corners are floor to ceiling 2" OC703 chunk traps. Entire front wall is 1" OC 703 with an air gap, equipment rack in the back corner has a removable back panel that is 3' x 5' and that is a panel based bass trap to work on the upper bass frequencies (airgap is between the resonant panel and the 2" OC 703).


Plan right now is to use the remaining 2" OC703 I have to treat the first reflection points for all listening positions and then use diffusion on the rest. My back wall is roughly 2.5' from the rear row listening position. The original plan was to use an array of the mini fusors there but I am not sure if I will do that at this stage.


I am certainly not afraid to construct my own diffusors and I have a radius based design stuffed with OC703 that I am considering. I will post pics. as I make progress in my treatment fabrication.


----------



## GIK Acoustics

Sounds like you're definitely on the right path. I would look into diffusors roughly twice as deep as the MetroFusors (around 3-4" deep). You can use these on your back wall but also the rear side walls, and even the rear ceiling as well.


----------



## dynfan




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9330#post_22884815
> 
> 
> Sounds like you're definitely on the right path. I would look into diffusors roughly twice as deep as the MetroFusors (around 3-4" deep). You can use these on your back wall but also the rear side walls, and even the rear ceiling as well.



Thanks for the advice. I just measured the mini fusors and they are 5" deep. I currently have about 15 of them and can at least try them out stuffed with OC and see how they work.


----------



## ellisr63




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9330#post_22875858
> 
> 
> I thought I'd share my some build pictures of my N31+6 panel. Built with 3/16" gatorboard and hot glue. The cavities will be filled with OC703. Should be finished and installed tonight on the back wall! Hopefully will turn my little room into a concert hall.



Did you buy 4x8 sheets... If so how many did you get and where?


----------



## HaroldKumar

I bought all the pieces pre-cut (1/16 tolerance) from 8x4' at www.artsupply.com . Just email Mira and tell her what you need. It's $71 per 8x4 sheet cut how you want. Since I had mine cut into 32" high pieces shipping charges were only $30 for 3 boards.


----------



## pepar

Harold, how did you fix the well depth, i.e. the location that the "bottom" piece would be glued?


----------



## HaroldKumar

Pepar, I had a carpenter build it, he's a former architectural model maker and has been gluing foam for 30 years. so he's got skills.


I watched him put some pieces on. He basically glued a well and a fin together on the table, then placed the piece into the frame, and hot glued it from the back. The skill is he uses just the right amount of glue to seal everything, but without any oozing or bubbles or trailers.


I can tell you my wife commented on how beautiful it is. If anyone's interested PM me, he is out of work, so maybe he can build some more.


I'll post some pics of it on the wall tomorrow.


OK, on the important part....... This thing sounds amazing, it really does make the room feel bigger, a lot bigger quite frankly. If sometimes you feel like Stan Getz is 10 feet tall and blowing his horn 3 feet away from you, try a QRD diffuser, he'll get back on stage.


----------



## localhost127




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9300_100#post_22889051
> 
> 
> 
> OK, on the important part....... This thing sounds amazing, it really does make the room feel bigger, a lot bigger quite frankly. If sometimes you feel like Stan Getz is 10 feet tall and blowing his horn 3 feet away from you, try a QRD diffuser, he'll get back on stage.













identify any other boundaries incident of later-arriving sparse energies and continue to place RPGs there!


----------



## HaroldKumar

I have 10 RPG skyline diffusors that I got a great deal on. I've been experimenting with them, but they don't seem as effective as the QRD. That could be because my custom QRD is huge around 2100 sq inches. One place I liked the RPGs was on floor like a mat at first reflection point. A studio friend says put the RPGs on ceiling directly above seating position. I'm only using two right now on the front wall between speakers. I could put a bunch on front wall and/or ceiling. Another possible location is sidewalls up high.


Can you have too much diffusion?


----------



## pepar




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9330#post_22890640
> 
> 
> I have 10 RPG skyline diffusors that I got a great deal on. I've been experimenting with them, but they don't seem as effective as the QRD. That could be because my custom QRD is huge around 2100 sq inches. One place I liked the RPGs was on floor like a mat at first reflection point. A studio friend says put the RPGs on ceiling directly above seating position. I'm only using two right now on the front wall between speakers. I could put a bunch on front wall and/or ceiling. Another possible location is sidewalls up high.
> 
> 
> Can you have too much diffusion?



The QRDs you are building and the "Cityscapes" are different tools. I got a good deal on some of the latter as well, but I am thinking what I should use are QRDs....


----------



## localhost127




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9300_100#post_22890640
> 
> 
> 
> Can you have too much diffusion?



this depends on the design requirements for the total specular response you wish to achieve.


the problem with "too much diffusion" it is generally via the over-application of NON-broadband diffusion.


another issue is the construction of large arrays (to cover large sq area surfaces) via repeated applications of the same diffuser type/design (periodicity) - of which specular lobing is exhibited. this is why inverse panels (as you will note is available for calculation in QRDude) are utilized, and the array can be formed via a pseudo-random sequence such as the Barker Code.


QRDude technical guide snips much from _Acoustic Absorbers and Diffusers_ (Cox/D'Antonio):
http://www.subwoofer-builder.com/qrdude-user-guide-lobes.htm 


you could also apply Binary Amplitude Diffusers (BAD) panels around the room (which offer spatial but NO temporal dispersion, unlike the phase gratings). you could even curve the BAD surface to form a poly. plenty of options to assist in getting the energy as well mixed as possible.


----------



## HaroldKumar

Here's some pictures of the QRD diffuser installed on the wall. Also the front wall setup. Sorry about the dark images, the black room is great for movies, not so great for pics.


----------



## localhost127

if you have more of the 2d skyline PRDs, may i suggest lining the outer face of your rear LF corner absorbers with them -


----------



## scsmitty

I'm planning on building some 8" tall x 12" wide soffits in my small theater room (11' x 15'). Would that size of soffit be good enough to use as bass traps? Thought about building the frames and covering them in fabric so that the sides and bottom would be open. I have some Roxul AFB that I can use inside them, Would that be a good choice or should I get something different? Thanks.


----------



## HaroldKumar

If you see my post just above and the pic, you will notice the narrow room I have.


I don't want to put up 4" sidewall first reflection absorbers as it makes the room even smaller, so I had a thought to cut out a square of the actual wall and embed the absorber into the wall. This would look good I think. I realize it's only 3.5 inches to work with but maybe they could stick out an inch or two.


Dumb idea? Anyone try this?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *scsmitty*  /t/255432/acoustical-treatments-master-thread/9360#post_22898645
> 
> 
> I'm planning on building some 8" tall x 12" wide soffits in my small theater room (11' x 15'). Would that size of soffit be good enough to use as bass traps? Thought about building the frames and covering them in fabric so that the sides and bottom would be open. I have some Roxul AFB that I can use inside them, Would that be a good choice or should I get something different? Thanks.



These would work pretty well. They aren't super thick so they won't go really low, but they should still provide pretty good absorption around 80-100 Hz and up.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9360#post_22901401
> 
> 
> If you see my post just above and the pic, you will notice the narrow room I have.
> 
> 
> I don't want to put up 4" sidewall first reflection absorbers as it makes the room even smaller, so I had a thought to cut out a square of the actual wall and embed the absorber into the wall. This would look good I think. I realize it's only 3.5 inches to work with but maybe they could stick out an inch or two.
> 
> 
> Dumb idea? Anyone try this?



This would work well for treatment, but could be bad for isolation and increase noise transmission into and out of your room.


----------



## scsmitty




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9360#post_22902182
> 
> 
> These would work pretty well. They aren't super thick so they won't go really low, but they should still provide pretty good absorption around 80-100 Hz and up.



Thanks for the info. I was just making sure that it wouldnt be a waste of time for me to build the soffits for anything other than looks.


----------



## angryht

I'm getting ready to build some bass traps for my room using OC703 (2" thick). I'll be picking up some 2' x 4' panels today. My approach was to double up the 703 creating a 4" thick panel and cover them with the black ponte material (speaker cloth) using a 1"x 2" backing frame. I have a very limited space; theater room is only about 9' wide by 13' long – actually only 8’ wide at the screen end of the room. A few questions about size and placement:



What are the smallest dimensions that would still be effective, 2’ by 2’ or even 1’ by 1’? It seems like most standard sizes are 2’ by 4’ but I have seen some minis that are 2’ by 2’; and I guess there are some triangular ones out there but in my case there are other obstructions that are in the way of that too. I would like to put the first 2 traps behind the speakers straddling either the wall/wall/ceiling corner or the wall/wall/floor corner, but even if they are 2’ by 2’ that would obstruct part of the screen. They would need to be closer to 1’ by 1’ to fit without. The back corners also have things in the way. Would it be as effective to place them either the wall/floor or wall/ceiling corners? I think there would be room to place them at the floor/wall corners either on the sides or between the speakers. Does it matter which one, side walls or front walls?
Should there be any other materials placed in the bass trap like a poly?


----------



## HaroldKumar

Your room is about the same as mine. Mine is 15.5lx8.5wx10.5h. I didn't have any problem getting 2x4' traps in the corners. How high is room? Do you have any pics? Is it a dedicated room?


----------



## kertofer

Why don't you use some super chunk corner traps? I built my traps as corner traps by cutting OC703 into essentially triangles that are about 18" long on the 2 short sides and stacked that almost ceiling high. I was only able to put them in the front 2 corners due to windows and doors near the back corners, but even just the 2 of them made a significant difference in the bass performance of the room.


----------



## angryht




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9360#post_22910259
> 
> 
> Your room is about the same as mine. Mine is 15.5lx8.5wx10.5h. I didn't have any problem getting 2x4' traps in the corners. How high is room? Do you have any pics? Is it a dedicated room?



Yep, it's a dedicated room but there is an uneven soffit over the screen.


Here is the layout. Sorry, I can't seem to size my image properly.

 


The dashed line is the doglegged soffit shape. The floor to ceiling height is only 6'-4" under that but 7'-3" everywhere else. There is a window (not shown) just to the left and a bit back from the left speaker (typical little basement window but covered with linacoustic).


Here is a picture of that front left corner (sorry it's kind of a dark photo):
 


Another shot of just the front:


----------



## angryht




> Quote:
> Originally Posted by *kertofer*  /t/255432/acoustical-treatments-master-thread/9360#post_22910847
> 
> 
> Why don't you use some super chunk corner traps? I built my traps as corner traps by cutting OC703 into essentially triangles that are about 18" long on the 2 short sides and stacked that almost ceiling high. I was only able to put them in the front 2 corners due to windows and doors near the back corners, but even just the 2 of them made a significant difference in the bass performance of the room.



Good point, but I have my speakers pushed into the corners (I know, I know, I shouldn't, but I need to). I suppose I could even put them at an angle and straddle the speaker stands.


----------



## Nightlord

Speakers won't mind being put into a chunk of insulation. Just make a hole for them in the trap.


----------



## HaroldKumar

Angryht, not a lot of real estate to work with as the ceiling is so low and variable.


One option is move the seating position up 4 feet and use smaller screen (yikes I know), then you'd free up corner space.


Or maybe flip the room around and put the screen on the 9.5 foot side?


----------



## angryht




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9360#post_22911380
> 
> 
> Angryht, not a lot of real estate to work with as the ceiling is so low and variable.
> 
> 
> One option is move the seating position up 4 feet and use smaller screen (yikes I know), then you'd free up corner space.
> 
> 
> Or maybe flip the room around and put the screen on the 9.5 foot side?



Well, actually, I am considering an AT screen. That would enable me to put some treatments in the corners behind the screen.


----------



## angryht

Any thoughts on these questions? I am thinking that the 2' by 2' might fit better in the room but I'm not sure how effective they would be.


> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9360#post_22910196
> 
> 
> What are the smallest dimensions that would still be effective, 2’ by 2’ or even 1’ by 1’? It seems like most standard sizes are 2’ by 4’ but I have seen some minis that are 2’ by 2’; and I guess there are some triangular ones out there but in my case there are other obstructions that are in the way of that too. I would like to put the first 2 traps behind the speakers straddling either the wall/wall/ceiling corner or the wall/wall/floor corner, but even if they are 2’ by 2’ that would obstruct part of the screen. They would need to be closer to 1’ by 1’ to fit without. The back corners also have things in the way. Would it be as effective to place them either the wall/floor or wall/ceiling corners? I think there would be room to place them at the floor/wall corners either on the sides or between the speakers. Does it matter which one, side walls or front walls?
> Should there be any other materials placed in the bass trap like a poly?


----------



## HaroldKumar

With an AT screen you have enough room to put in the superchunk traps on your front wall like kertofer suggested. This is the most bang per sq ft probably. The only downside is that takes a lot of material, but you are only doing a few traps should be OK cost wise.


I think if you do a superchunk trap on each front corner (and maybe something on the back wall top corners), you will get a dramatic improvement in bass, LF and also speech in films will be much clearer.


Also, one reason I suggested moving the seating position towards middle of room is seating against the back wall is considered a no no, maybe you could do some OC703 against back wall at first reflection.


----------



## HaroldKumar

What are peoples thoughts on this hybrid OC703/R38 trap?

http://www.gearslutz.com/board/8616119-post30.html 


I have straddled OC703 traps in all four corners and I'm thinking I could get more LF performance with R38 behind them? Worth it?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9360#post_22914301
> 
> 
> What are peoples thoughts on this hybrid OC703/R38 trap?
> 
> http://www.gearslutz.com/board/8616119-post30.html
> 
> 
> I have straddled OC703 traps in all four corners and I'm thinking I could get more LF performance with R38 behind them? Worth it?



You would get some additional absorption around 60 Hz and lower. Your traps likely absorb pretty good from 80 Hz and up as is, stuffing with fiberglass should lower that down at least a half octave.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9360#post_22913979
> 
> 
> Any thoughts on these questions? I am thinking that the 2' by 2' might fit better in the room but I'm not sure how effective they would be.



A couple of quick points:


Most absorbers are 2' x 4' because

A.) That is the size the absorption cores come in.

B.) It works out to actually be quite a convenient size in most cases.


However, there isn't many reasons that twice as many 2x2s wont work as well as 2x4s. There might be some slight differences in terms of diffraction, but not detrimental. In the case of 1x1s, 8 of them would be more or less be equal to a 2x4 absorber. But I do want to draw on the differences here. When you straddle a corner with a 2 foot wide trap, this means you have a large 12" airgap between the middle of the panel and the corner, getting smaller as you go to the edges of the absorber. A 1x1 absorber will only have a 6" gap (which does make a large difference!). So, they won't work nearly as well for absorbing


----------



## angryht

As usual, great straight info. At this point I am going to go with 2' by 2'. If they won't fit at the front tri corners because of the current screen set up, maybe I could put them between the center and right and left speakers straddling the wall/floor corners. Then, if I do go with an AT sceen, I would be able to put them up in the front tricorner when the speakers are moved slightly forward. The 2' by 2' would probably give me the most flexibility.


----------



## angryht

Question about placement. If I place my 2' x 2' bass traps (4" thick with OC 703) in the corners, I need to lean them back so that the bottoms are 'kicked out' a bit. Other wise they are too tall and obstruct the screen. I will likely be able to rearrange when I get the AT screen set up but I wanted to ask for the mean time. The picture below shows what I mean. Is this poor placement?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9360#post_22934557
> 
> 
> Question about placement. If I place my 2' x 2' bass traps (4" thick with OC 703) in the corners, I need to lean them back so that the bottoms are 'kicked out' a bit. Other wise they are too tall and obstruct the screen. I will likely be able to rearrange when I get the AT screen set up but I wanted to ask for the mean time. The picture below shows what I mean. Is this poor placement?



You would want them kicked as little as possible, but it should be okay for temporary placement. For a lot of the tests we do when we try setups in our test room, we'll simply lean our 4" bass traps in the corner (with as little kick as possible). The more it completely straddles the corner the better, but we haven't seen drastically worse results with them a bit off.


----------



## angryht




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9360#post_22935570
> 
> 
> You would want them kicked as little as possible, but it should be okay for temporary placement. For a lot of the tests we do when we try setups in our test room, we'll simply lean our 4" bass traps in the corner (with as little kick as possible). The more it completely straddles the corner the better, but we haven't seen drastically worse results with them a bit off.


Good to know.. My other options for the front of the room would be either put them parallel to the front wall between the center and right & left; or to put them against the side wall (bottom kicked out to straddle the floor/wall corner in both cases). Any obvious do's or don't's? It seems like the typical order of business is to try and treat the main corners of the room but if it makes more sense to put them along the walls, maybe I should just do that, since they don't quite fit to straddle the floor/wall/wall properly.


----------



## grubadub




> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9360#post_22934557
> 
> 
> Question about placement. If I place my 2' x 2' bass traps (4" thick with OC 703) in the corners, I need to lean them back so that the bottoms are 'kicked out' a bit. Other wise they are too tall and obstruct the screen. I will likely be able to rearrange when I get the AT screen set up but I wanted to ask for the mean time. The picture below shows what I mean. Is this poor placement?



thanks for showing the pic because it sparks a question in my mind. i thought that acoustic panels should be placed to cover ear height (if you can't get floor to ceiling coverage). the 2' x 2' bass traps appear to be lower than ear height. so is the ear height requirement irrelevant with bass traps?


----------



## angryht




> Quote:
> Originally Posted by *grubadub*  /t/255432/acoustical-treatments-master-thread/9360#post_22936169
> 
> 
> so is the ear height requirement irrelevant with bass traps?


That's the way I understand it, but I'll wait for confirmation. Bass builds up in the corners, which is why the most effective traps are in the corner (broadband that is).


----------



## GIK Acoustics




> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9360#post_22935850
> 
> 
> Good to know.. My other options for the front of the room would be either put them parallel to the front wall between the center and right & left; or to put them against the side wall (bottom kicked out to straddle the floor/wall corner in both cases). Any obvious do's or don't's? It seems like the typical order of business is to try and treat the main corners of the room but if it makes more sense to put them along the walls, maybe I should just do that, since they don't quite fit to straddle the floor/wall/wall properly.



Corners would be best for bass control.



> Quote:
> Originally Posted by *grubadub*  /t/255432/acoustical-treatments-master-thread/9360#post_22936169
> 
> 
> thanks for showing the pic because it sparks a question in my mind. i thought that acoustic panels should be placed to cover ear height (if you can't get floor to ceiling coverage). the 2' x 2' bass traps appear to be lower than ear height. so is the ear height requirement irrelevant with bass traps?



They should be at ear height for first reflection panels (and other panels that are meant to absorb destructive phase related issues - iow, other early reflections). For purely bass trapping, the height shouldn't affect the absorption significantly. If you were trying to get a combo though, reflection control and bass trapping - they'd need to be at ear height (or speaker height - or better yet, inbetween the two)



> Quote:
> Originally Posted by *angryht*  /t/255432/acoustical-treatments-master-thread/9360#post_22936235
> 
> 
> That's the way I understand it, but I'll wait for confirmation. Bass builds up in the corners, which is why the most effective traps are in the corner (broadband that is).



Yes. And the reason bass builds up in corners is because sound travels in solids (like drywall) faster than in air. So bass waves tend to propagate along boundaries until they terminate in the corners. Also you get the benefit of dampening two modes at once in the corner.


----------



## Jay5298




> Quote:
> Originally Posted by *HaroldKumar*  /t/255432/acoustical-treatments-master-thread/9360#post_22914301
> 
> 
> What are peoples thoughts on this hybrid OC703/R38 trap?
> 
> http://www.gearslutz.com/board/8616119-post30.html
> 
> 
> I have straddled OC703 traps in all four corners and I'm thinking I could get more LF performance with R38 behind them? Worth it?



I'm thinking of doing the same thing. I have OC 705 with the FRK facing on the front straddling four corners in my theater. My traps are trapezoid shaped and sit more flush with the wall, so I don't have as big a gap behind them probably about 10" or so. Have you tried this yet, if so has it improved the sound?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Jay5298*  /t/255432/acoustical-treatments-master-thread/9360#post_22998797
> 
> 
> I'm thinking of doing the same thing. I have OC 705 with the FRK facing on the front straddling four corners in my theater. My traps are trapezoid shaped and sit more flush with the wall, so I don't have as big a gap behind them probably about 10" or so. Have you tried this yet, if so has it improved the sound?



I think its a wonderful idea. You can play with the following calculator to get a feel for the benefits of using this method: http://www.stanleyhallstudios.co.uk/pacalc/ 

Of course this is simply a calculation, but can still give a good indication to the difference of materials.

Flow resistivity of OC705 is roughly 30,000 - resistivity of pink fluffy is about 5,000

Use the average depth of the corner to get a somewhat more accurate picture.

I also recommend selecting "Miki (1990)" from the "Model" section on the left.


Cheers!


----------



## Jay5298




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9360#post_22999733
> 
> 
> I think its a wonderful idea. You can play with the following calculator to get a feel for the benefits of using this method: http://www.stanleyhallstudios.co.uk/pacalc/
> 
> Of course this is simply a calculation, but can still give a good indication to the difference of materials.
> 
> Flow resistivity of OC705 is roughly 30,000 - resistivity of pink fluffy is about 5,000
> 
> Use the average depth of the corner to get a somewhat more accurate picture.
> 
> I also recommend selecting "Miki (1990)" from the "Model" section on the left.
> 
> 
> Cheers!



Well it looks like it wont make much difference at all according to the graph. Green is with the OC705 and a 10" air gap, which is what I have now. Blue is with the OC705 and 10" of pink fluffy insulation behind it.  http://www.stanleyhallstudios.co.uk/pacalc/pacalc.php?m=4&s11=2&d11=101.6&v11=30000&s12=2&d12=254&v12=5000&s21=2&d21=101.6&v21=30000&s22=1&d22=254


----------



## Kensmith48

I'm thinking of treating my front wall. I have the main speakers + 2 dedicated subs up front and was wondering whether to use bass traps in the corners or 4" x 24" x48" bass trap panels or regular 4"x 24"x 48" panels behind the speakers.Since I only have 3' from the corner to the screen, I can choose only one. My room is approx. 15'x 29".I will also be adding bass traps in the rear corners of the room. I should also add that this is a dedicated basement theater room with 7.2 sound used mainly for movies. I have direct radiating speakers up front with bi-poles for surrounds.


Thanks,

Ken


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Jay5298*  /t/255432/acoustical-treatments-master-thread/9390#post_23025515
> 
> 
> Well it looks like it wont make much difference at all according to the graph. Green is with the OC705 and a 10" air gap, which is what I have now. Blue is with the OC705 and 10" of pink fluffy insulation behind it.  http://www.stanleyhallstudios.co.uk/pacalc/pacalc.php?m=4&s11=2&d11=101.6&v11=30000&s12=2&d12=254&v12=5000&s21=2&d21=101.6&v21=30000&s22=1&d22=254



Take a look here instead: http://www.stanleyhallstudios.co.uk/pacalc/pacalc.php?e=h&r=r&m=4&s11=2&d11=101.6&v11=30000&s12=2&d12=254&v12=5000&s21=2&d21=101.6&v21=30000&s22=1&d22=254 


(Note: it will take a bit to load - maybe up to 30 seconds)


You'll notice a bit different of a graph. I chose high resolution first off, which wouldn't change it too much, but I changed it to random incidence. Since the absorber is in the corner where sound waves won't be directly going into it (as opposed to a reflection point where a lot of energy is going into the absorber), this gives a better calculation. The difference isn't usually 'huge' but with how cheap fluffy is, its usually worth the slight improvement.


In case your curious, the long load time is due to the high resolution option.



> Quote:
> Originally Posted by *Kensmith48*  /t/255432/acoustical-treatments-master-thread/9390#post_23044418
> 
> 
> I'm thinking of treating my front wall. I have the main speakers + 2 dedicated subs up front and was wondering whether to use bass traps in the corners or 4" x 24" x48" bass trap panels or regular 4"x 24"x 48" panels behind the speakers.Since I only have 3' from the corner to the screen, I can choose only one. My room is approx. 15'x 29".I will also be adding bass traps in the rear corners of the room. I should also add that this is a dedicated basement theater room with 7.2 sound used mainly for movies. I have direct radiating speakers up front with bi-poles for surrounds.
> 
> 
> Thanks,
> 
> Ken



I would go with the corner treatment. Modal resonance usually is a bigger factor than SBIR nulls when you have two subs. Using two subs helps to flatten out the nulls with careful placement, but modal resonance will still exist regardless of where you put your subs. So I'd go with thick corner traps - floor to ceiling if possible. Hopefully that makes sense!



> Quote:
> Originally Posted by *Kensmith48*  /t/255432/acoustical-treatments-master-thread/9390#post_23044418
> 
> 
> My room is approx. 15'x 29"



Wow, that is one _thin_ room!


----------



## steve71




> Quote:
> Originally Posted by *Dennis Erskine*  /t/255432/acoustical-treatments-master-thread#post_2177423
> 
> 
> Compromise between the two playback scenarios is not a good option. Effectively you're saying you're (a) willing to spend a bunch of money and (b) happy to make the room sound poorly in either case.
> 
> 
> If you have a good surround processor and a well set up multi-channel room, play your 2 channel recordings in multi-channel mode...a better result. I can assure you a good surround processor will do a whole bunch better job of creating the spaciousness than your room can accomplish.



OK, I realize this post is 10 years old, but I was wondering if Dennis (or anyone else) has an opinion on 7ch vs 9 or 11 channels for music playback in an appropriately treated room, optimized for movie playback.


In other words, will the extra channels provide benefit when listening to 2 ch music (with dsp providing the room sound via the surround channels).


Also any opinion for movie playback in 9 or 11 channels in a treated room? FWIW My theater is going to be large at 38x28ft and I will be using commercial theater speakers with 90x40 constant reflectivity horns. And yes I realize 99.786% of movies are only 5.1 and the extra channels are synthesized using DSP.


----------



## wse

 http://www.cepro.com/article/speaker_engineer_questions_home_theater_equalization_process/?utm_source=CEPWeekly&utm_medium=email 


That is so true


----------



## erkq




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9390#post_23115788
> 
> http://www.cepro.com/article/speaker_engineer_questions_home_theater_equalization_process/?utm_source=CEPWeekly&utm_medium=email
> 
> 
> That is so true



He misses a big distinction when he says "You don't tune a Steinway for the room." And that is, do you want your sound system to replicate instruments played in your home or do you want it to be a window into another world... another environment entirely? And, recordings have to be produced for each application, with the vast majority of recordings intended as windows into another world. They add reverb, eq and other things to control the feeling of space and environment.


When setting up our home theaters, we most definitely want the "window into another world" effect. Skyfall isn't being blown to bits inside our tiny little theaters. It's being blown to bits in a wide open plain. Our walls should disappear acoustically and the surround speakers should create the environment intended.


I think he really misses the point.


----------



## pepar




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9390#post_23115971
> 
> 
> 
> 
> I think he really misses the point.



Thanks. Not being a pro, I hesitated to weigh in, but there is a difference between an instrument producing a note and a system REproducing that note.


----------



## Kevin Snyder




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9390#post_23113701
> 
> 
> OK, I realize this post is 10 years old, but I was wondering if Dennis (or anyone else) has an opinion on 7ch vs 9 or 11 channels for music playback in an appropriately treated room, optimized for movie playback.
> 
> 
> In other words, will the extra channels provide benefit when listening to 2 ch music (with dsp providing the room sound via the surround channels).
> 
> 
> Also any opinion for movie playback in 9 or 11 channels in a treated room? FWIW My theater is going to be large at 38x28ft and I will be using commercial theater speakers with 90x40 constant reflectivity horns. And yes I realize 99.786% of movies are only 5.1 and the extra channels are synthesized using DSP.



Wow. Was that really 10 years ago? I remember reading that post when it was written, and looked forward to seeing which surround modes were most useful for music. I haven't seen much written about it, but I would be interested in hearing which surround modes people find best for music in a room treated for home theater.


----------



## krakhen




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9390#post_23115788
> 
> http://www.cepro.com/article/speaker_engineer_questions_home_theater_equalization_process/?utm_source=CEPWeekly&utm_medium=email
> 
> 
> That is so true



Considering our systems are only performing in one venue(our particular home theater), I don't think it's a waste of time to optimize for it.


That optimization should include treating the room though, but then there is no Automatic Audyssey *Physical* Room Correction, is there?


----------



## Dennis Erskine

Paul Hales, or the author, is making profuse use of "glittering generalities". Bad form.

Yes, poor microphones, lack of understanding what the instrumentation is telling you, and failing to listen are widespread faults; but, ignoring the fact there are professionals available is a big miss. I share his view that "automagic" systems frequently do a poor job; but, the very existence of these tools is telling the consumer audio calibration is necessary.


The whole Steinway analogy is a big miss (besides, use a real piano like a Bosendorfer







). As has been said above, properly tuning an instrument is a radically different objective than attempting to reproduce the recorded sound of that piano and venue in some other space.


----------



## Dennis Erskine

Addendum .... Bosendorfer may not tune their pianos to a room; but, they are very picky about the acoustics of the rooms the use to showcase their instruments:


Since October 2010 the new BÖSENDORFER-SAAL im MOZARTHAUS VIENNA *) is running. It is the third one in the history of Bösendorfer and it is situated in the Mozarthaus Vienna, right in the city center of Vienna near St. Stephan's Cathedral. (Stephansplatz)


The beautifully designed hall in the vaulted cellar of the building of Mozart's flat in Vienna, has excellent acoustics and is equipped with a Bösendorfer Model 200.


----------



## pepar




> Quote:
> Originally Posted by *Kevin Snyder*  /t/255432/acoustical-treatments-master-thread/9390#post_23117150
> 
> 
> Wow. Was that really 10 years ago? I remember reading that post when it was written, and looked forward to seeing which surround modes were most useful for music. I haven't seen much written about it, but I would be interested in hearing which surround modes people find best for music in a room treated for home theater.



I actually have two surround speaker configurations that I manually swap for hi-res multichannel music or everything else. (The qualifier would be that the music is mixed from an in-the-band perspective.)


The MCH music config is five identical monopoles with the surrounds at 120 degrees. There are monopole rear surrounds at 180 degrees, but they rarely have anything to reproduce. In the cinema/concert/TV the surrounds are tripole at 90 degrees (and those monopole rear surrounds). Along with swapping speaker connections, I load Audyssey calibrations for each speaker configuration.


My own listening tells me that a system optimized for movies does not work for in-the-band suround music mixes as all channels can carry the same full range/full power content and, as far as I know, is MIXED with surrounds at 110-120. And the corollary is that I find watching movies with this config to be somewhat disturbing; the surround content is too "direct" and is coming from the wrong direction.


Admittedly, this scheme is not an elegant solution and is a bit of a pain to switch when guests are here and we are trying to make the most of our time together. But most of my home theater use is solitary ... with the two type of content the same for any given session.


Jeff


----------



## sdurani




> Quote:
> Originally Posted by *Kevin Snyder*  /t/255432/acoustical-treatments-master-thread/9390#post_23117150
> 
> 
> I would be interested in hearing which surround modes people find best for music in a room treated for home theater.


I got a chance to listen to some 2-channel music in an Erskine-designed theatre last year. Can't say if it was specifically "treated for home theater", but it was carefully tuned using a combination of placement, treatment and equalization. Of the surround modes we tried, PLIIx Music mode turned out to be my preference. The amount of surround extraction is user-adjustable, and it was dialed in to make effective use of the surrounds without ever calling attention to the surround speakers themselves.


The end result was a wide, lush soundstage that appeared to stretch beyond the side walls of the room; exactly what I want when listening to 2-channel music (except it took more than 2 speakers to achieve that result). The combination of PLII/PLIIx Music mode and a well treated room sound excellent for music listening, especailly since you can tailor the results to your personal preference (user-adjustable centre extraction and surround extraction).


----------



## Kevin Snyder




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9390#post_23119312
> 
> 
> I got a chance to listen to some 2-channel music in an Erskine-designed theatre last year. Can't say if it was specifically "treated for home theater", but it was carefully tuned using a combination of placement, treatment and equalization. Of the surround modes we tried, PLIIx Music mode turned out to be my preference. The amount of surround extraction is user-adjustable, and it was dialed in to make effective use of the surrounds without ever calling attention to the surround speakers themselves.
> 
> 
> The end result was a wide, lush soundstage that appeared to stretch beyond the side walls of the room; exactly what I want when listening to 2-channel music (except it took more than 2 speakers to achieve that result). The combination of PLII/PLIIx Music mode and a well treated room sound excellent for music listening, especailly since you can tailor the results to your personal preference (user-adjustable centre extraction and surround extraction).



I appreciate the input. Exactly what I was looking for!


----------



## steve71




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9390#post_23119312
> 
> 
> I got a chance to listen to some 2-channel music in an Erskine-designed theatre last year. Can't say if it was specifically "treated for home theater", but it was carefully tuned using a combination of placement, treatment and equalization. Of the surround modes we tried, PLIIx Music mode turned out to be my preference. The amount of surround extraction is user-adjustable, and it was dialed in to make effective use of the surrounds without ever calling attention to the surround speakers themselves.
> 
> 
> The end result was a wide, lush soundstage that appeared to stretch beyond the side walls of the room; exactly what I want when listening to 2-channel music (except it took more than 2 speakers to achieve that result). The combination of PLII/PLIIx Music mode and a well treated room sound excellent for music listening, especailly since you can tailor the results to your personal preference (user-adjustable centre extraction and surround extraction).




That sound encouraging. Strangely enough I find myself with twelve identical Altec A6 Voice of the theater speakers. I only wanted to buy four pairs, but it was an all or nothing deal. So I guess I may as well go ahead with 11.2. I just wish there were some 11.2 pre/pro options.


Just two of these puppies were hitting 115db peaks in my seat, twenty feet away, with around 100watts each... and sounded amazing all the while. The garage (1/2 of the future HT) has 12" of fiberglass insulation on all but the floor and the back garage door. Guess it must smooth the room response, because I have NEVER heard bass like that outside of a live out door concert. Wife and kids didn't hear a thing in the main house (a dream come true!)


I don't have a wide angle lens, so I couldn't get everything in, but you get the idea...







These were taken out of a theater in Alaska that closed down.


----------



## Peter M




> Quote:
> Originally Posted by *Kevin Snyder*  /t/255432/acoustical-treatments-master-thread/9350_50#post_23117150
> 
> 
> I would be interested in hearing which surround modes people find best for music in a room treated for home theater.



Hi Kevin,


I have an Erskine designed room with a 9.5 Procella system and I would never ever listen in stereo again. PLIIx music mode sounds glorious !!


Cheers,


----------



## audiovideoholic




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9390#post_23121398
> 
> 
> That sound encouraging. Strangely enough I find myself with twelve identical Altec A6 Voice of the theater speakers. I only wanted to buy four pairs, but it was an all or nothing deal. So I guess I may as well go ahead with 11.2. I just wish there were some 11.2 pre/pro options.



Those are some big speakers for home theater lol. Will be pleanty of sound!


----------



## wse




> Quote:
> Originally Posted by *Peter M*  /t/255432/acoustical-treatments-master-thread/9390#post_23121405 Hi Kevin, I have an Erskine designed room with a 9.5 Procella system and I would never ever listen in stereo again. PLIIx music mode sounds glorious !! Cheers,


Cool, pro speakers!


----------



## steve71




> Quote:
> Originally Posted by *Peter M*  /t/255432/acoustical-treatments-master-thread/9390#post_23121405
> 
> 
> Hi Kevin,
> 
> 
> I have an Erskine designed room with a 9.5 Procella system and I would never ever listen in stereo again. PLIIx music mode sounds glorious !!
> 
> 
> Cheers,



Sounds awesome, thanks for chiming in! I used to live in Rose Bay. Sydney is such a beautiful city.



> Quote:
> Originally Posted by *audiovideoholic*  /t/255432/acoustical-treatments-master-thread/9390#post_23121492
> 
> 
> Those are some big speakers for home theater lol. Will be pleanty of sound!



You should see the subs







. I have a 30x40ft detached building to devote to HT this time round, so it shouldn't be too hard to hide them. They're pretty shallow, ~ 1.5ft and 7 of 11 go on the front wall.


----------



## Kevin Snyder




> Quote:
> Originally Posted by *Peter M*  /t/255432/acoustical-treatments-master-thread/9390#post_23121405
> 
> 
> Hi Kevin,
> 
> 
> I have an Erskine designed room with a 9.5 Procella system and I would never ever listen in stereo again. PLIIx music mode sounds glorious !!
> 
> 
> Cheers,



Fantastic! I'm planning on going Procella as well, but probably not 9.5!!! Looking forward to trying PLIIx.


----------



## sdurani




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9390#post_23121398
> 
> 
> I just wish there were some 11.2 pre/pro options.


The only one I can think of is the recently released Marantz 8801.


----------



## erkq




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9390#post_23121398
> 
> 
> That sound encouraging. Strangely enough I find myself with twelve identical Altec A6 Voice of the theater speakers. I only wanted to buy four pairs, but it was an all or nothing deal. So I guess I may as well go ahead with 11.2. I just wish there were some 11.2 pre/pro options.
> 
> 
> Just two of these puppies were hitting 115db peaks in my seat, twenty feet away, with around 100watts each... and sounded amazing all the while. The garage (1/2 of the future HT) has 12" of fiberglass insulation on all but the floor and the back garage door. Guess it must smooth the room response, because I have NEVER heard bass like that outside of a live out door concert. Wife and kids didn't hear a thing in the main house (a dream come true!)
> 
> 
> I don't have a wide angle lens, so I couldn't get everything in, but you get the idea...
> 
> 
> 
> 
> 
> 
> 
> These were taken out of a theater in Alaska that closed down.



Very nice woofers, especially for their time. Their combination of sound, efficiency and deep bass response (in a properly large box) is unmatched. I'm a great fan, having purchased my first pair of 416-8A's from Electronics Plus (in San Rafael) in 1978 for $95 each! And, I still have them in my living room speakers system. They work like the day they were new. But I've never been a big fan of their horns. Instead I pair them up with Dynaudio D-76's and Esotar D-260's in a tri-amp'd configuration so efficiencies and phase match. It's all very sweet.


I, too, bought a batch from a closing theater (in Oregon) and used 8 of those for an IB sub. They did a very credible job, but I later swapped them out for a set of AE-IB15's, which do a very *in*credible job!


EDIT: BTW, my 416's -3dB point is 18Hz in their 6 cu. ft. box!


----------



## pepar




> Quote:
> Originally Posted by *Kevin Snyder*  /t/255432/acoustical-treatments-master-thread/9390#post_23122135
> 
> 
> Fantastic! I'm planning on going Procella as well, but probably not 9.5!!! Looking forward to trying PLIIx.



Procella had the second best sounding demo at CEDIA two years ago. It sounded incredible, but second nonetheless IMO.


----------



## Dennis Erskine

Yeah....and they were using some experimental acoustic treatments...the experiment didn't measure up. Now they are using Quest treatments. Last year was a big improvement.


----------



## audiovideoholic




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9390#post_23122625
> 
> 
> The only one I can think of is the recently released Marantz 8801.



The Denon 4311 does 11.2 as well.


----------



## sdurani




> Quote:
> Originally Posted by *audiovideoholic*  /t/255432/acoustical-treatments-master-thread/9390#post_23124647
> 
> 
> The Denon 4311 does 11.2 as well.


Right, but he was asking about pre-pros.


----------



## Peter M




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9400_50#post_23121620
> 
> 
> I used to live in Rose Bay. Sydney is such a beautiful city.



LOL ! It certainly is if you live in Rose Bay !!!


----------



## Peter M




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9400_50#post_23122887
> 
> 
> Procella had the second best sounding demo at CEDIA two years ago. It sounded incredible, but second nonetheless IMO.



Pepar,


I was at CEDIA two years ago. Which room did you think was the best ?


Cheers,


----------



## pepar




> Quote:
> Originally Posted by *Peter M*  /t/255432/acoustical-treatments-master-thread/9390#post_23125260
> 
> 
> Pepar,
> 
> 
> I was at CEDIA two years ago. Which room did you think was the best ?
> 
> 
> Cheers,



I had a near-religious experience in the Wisdom Audio demo. While they did come in in the wee hours of the morning when the venue was quiet and do an Audyssey Pro calibration (MultEQ XT), they had no room treatments other than some bass traps. Otherwise the room was the same cheap carpet-covered popup traveling box you find at trade shows.


I was not in the sweet spot, yet the imaging was spot on. The female vocal (I forget who) was as present and immediate as if she was singing live. All the instruments had a presence that I had never heard before in a home theater. Of course the speakers were $30k - $40k EACH so short of a Powerball win, I will never own them. But that hasn't lifted the curse from me. I did recently check back at their site and found that they have introduced a more affordable line of speakers that I am anxious to hear. I *think* it is their planar magnetic technology that made the difference, so I am hoping that the new line of speakers "captures the essence" of their high end.


Jeff


----------



## wse




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9390#post_23122887 Procella had the second best sounding demo at CEDIA two years ago. It sounded incredible, but second nonetheless IMO.


Which one was first?


----------



## pepar




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9390#post_23126614
> 
> 
> Which one was first?



Wisdom Audio. See my post above yours.


Jeff


----------



## steve71




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9390#post_23122625
> 
> 
> The only one I can think of is the recently released Marantz 8801.



Thanks for that! Looks like a winner for my application!


> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9390#post_23122786
> 
> 
> Very nice woofers, especially for their time. Their combination of sound, efficiency and deep bass response (in a properly large box) is unmatched. I'm a great fan, having purchased my first pair of 416-8A's from Electronics Plus (in San Rafael) in 1978 for $95 each! And, I still have them in my living room speakers system. They work like the day they were new. But I've never been a big fan of their horns. Instead I pair them up with Dynaudio D-76's and Esotar D-260's in a tri-amp'd configuration so efficiencies and phase match. It's all very sweet.
> 
> 
> I, too, bought a batch from a closing theater (in Oregon) and used 8 of those for an IB sub. They did a very credible job, but I later swapped them out for a set of AE-IB15's, which do a very *in*credible job!
> 
> 
> EDIT: BTW, my 416's -3dB point is 18Hz in their 6 cu. ft. box!



A theater in Oregon eh? Small world! Those A6a's have 3154's (IIRC). I've heard the 416's in A7 cabs a few times but never as a direct radiator. I was all set to go with a handful of IB15's in my last theater, but we moved before I got the chance. This time round I'll be using four horn loaded, high excursion 18". Won't go as low as your IB's, but with 11,000 cubic ft an IB would be out of the question.


What didn't you like about the Altec horns? I've heard and owned a bunch of them over the last few years (288 CD's) and to my ears, they have a mid range to die for. The A6a's are a little rolled off, but a worthy trade off for that mid-range. I've tried tri-amped with a Gauss 1502's and 515g's in DIY 80hz bass horns, but I wanted to have the same speakers all the way round and 7-11 active speaker are just too noisy with the high efficiency drivers. Unless you're prepared to spend BIG on active crossovers.


Sure sounds like you have a killer setup though, do you have any links to your speaker/theater build?



> Quote:
> Originally Posted by *Peter M*  /t/255432/acoustical-treatments-master-thread/9390#post_23125251
> 
> 
> LOL ! It certainly is if you live in Rose Bay !!!



Hehe. Lots of fond memories of Bondi.


----------



## erkq




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9420#post_23129119
> 
> 
> ...
> 
> A theater in Oregon eh? Small world! Those A6a's have 3154's (IIRC). I've heard the 416's in A7 cabs a few times but never as a direct radiator. I was all set to go with a handful of IB15's in my last theater, but we moved before I got the chance. This time round I'll be using four horn loaded, high excursion 18". Won't go as low as your IB's, but with 11,000 cubic ft an IB would be out of the question.
> 
> 
> What didn't you like about the Altec horns? I've heard and owned a bunch of them over the last few years (288 CD's) and to my ears, they have a mid range to die for. The A6a's are a little rolled off, but a worthy trade off for that mid-range. I've tried tri-amped with a Gauss 1502's and 515g's in DIY 80hz bass horns, but I wanted to have the same speakers all the way round and 7-11 active speaker are just too noisy with the high efficiency drivers. Unless you're prepared to spend BIG on active crossovers.
> 
> 
> Sure sounds like you have a killer setup though, do you have any links to your speaker/theater build?
> 
> Hehe. Lots of fond memories of Bondi.



It's been decades, but I thought they "rang". I just started using other drivers and never looked back. So perhaps a re-eval is in order. Also, when using the 416's as direct radiators the efficiency doesn't match well and other direct radiators (like my beloved Dynaudios) work well.


I built my theater's speakers using all Dynaudio drivers (except for those 8 AE's of course) so efficiency isn't a problem and they stay nice and quiet as tri-amp'd speakers.


Wow... horn loading bass for a 11,000 cu. ft. space? That sounds like a fun project. Here's a horn to look at. I'm sure you've seen this before: http://www.royaldevice.com/custom31.htm 


I have no links. It doesn't photograph well. All the dark walls that stay hidden jump to the fore with a flash and there's not enough light to not use a flash. The problem is, when the sound and pic get to a certain point (and I'm there) work on the room stops!


----------



## steve71




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9420#post_23134003
> 
> 
> It's been decades, but I thought they "rang". I just started using other drivers and never looked back.



They do have a lot more HF energy (due to their constant directivity design) than direct radiators, which beam. So in an untreated room they will ring more. But in a treated room it's not an issue, and really that's not the speakers fault. You can also band-aid it a bit with eq.


The other issue with them is they don't terminate into free air correctly, causing diffraction. There are better horns (modern) out their in that regard, but a little modification can work wonders. Especially with these MRII horns as they are pretty close to ideal anyway. The earlier multicells and manta-ray horns make correct termination into free air a bit harder, but still possible.


Finally, the other compromise is that the center to center spacing of big horns can never comply with the 1/4 wavelength rule. So there will be lobes at the crossover frequency.


Every design has it's compromise though and as I'm sure you know since you DIY! Danley's unity horns might be the exception. I'm dying to hear those babies!



> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9420#post_23134003
> 
> 
> I built my theater's speakers using all Dynaudio drivers (except for those 8 AE's of course) so efficiency isn't a problem and they stay nice and quiet as tri-amp'd speakers.



What are you using for an active x-over? I could get the noise down to acceptable level's but it's really only an issue with the 115db/w/m horns.


> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9420#post_23134003
> 
> 
> Wow... horn loading bass for a 11,000 cu. ft. space? That sounds like a fun project. Here's a horn to look at. I'm sure you've seen this before: http://www.royaldevice.com/custom31.htm



I'm crazy, but not that crazy







He must need some serious delays for his mains!


I'll be building these guys, just waiting on the back order drivers. "1 meter peak output numbers results in output levels of 130-140dB from a single cabinet over the entire 20-100Hz range and greater than 127dB at 16Hz".

http://www.data-bass.com/data?page=system&id=45 





Anyway, getting back on topic I ordered two boxes (24 panels) of 2x4ft OC 703. Amazon had free shipping and a good price. I was very concerned that locating the stuff was going to be a pitta.


Now if only I could get my EMU 404 sound card to work with my laptop, I actually might be able to start taking some measurements when the stuff arrives.


----------



## erkq




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9420#post_23139145
> 
> 
> ...
> 
> What are you using for an active x-over? I could get the noise down to acceptable level's but it's really only an issue with the 115db/w/m horns.
> 
> ...
> 
> I'll be building these guys, just waiting on the back order drivers. "1 meter peak output numbers results in output levels of 130-140dB from a single cabinet over the entire 20-100Hz range and greater than 127dB at 16Hz".
> 
> http://www.data-bass.com/data?page=system&id=45
> 
> ...



It's taken me a while to answer because I don't want to hijack the thread *and* I'm embarrassed to admit I'm using Behringer x-overs. I tri-amp'd my whole 7.1 system and buying more expensive x-overs would have just killed the project. I *still* like the setup better than any passive x-over I've managed to design, though. Crossovers are the toughest part of DIY speakers for me. And... my Dynaudios are probably just under 90 db/w/m, so I don't hear any hissing.


Interesting stuff about the HF horns. So I knew what I was hearing, even back in my 20's. I definitely did *not* have a treated room.


Killer subs! I would love to build me some of those. I think it would destroy my house, though!










OK... enough OT I guess... but it was fun for me.


----------



## wse

Originally Posted by erkq Wow... horn loading bass for a 11,000 cu. ft. space? That sounds like a fun project. Here's a horn to look at. I'm sure you've seen this before: http://www.royaldevice.com/custom31.htm 


This is unheard, you could cause a seismic trigger with those subs!


----------



## steve71




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9420#post_23143343
> 
> 
> I'm embarrassed to admit I'm using Behringer x-overs. I tri-amp'd my whole 7.1 system



Wow, that is harcore.







I was headed down that route but couldn't pass us the deal I got on the Altecs.


No need to be embarrassed about the ringer'. There isn't much choice in affordable x-overs. Electronics matter, but the smart place to spend your money is on room treatments and speakers (as I'm sure everyone here knows!).


I have a nice ATI 2007 amp arriving on Monday, but I'm honestly more excited about the OC 703 that's coming on Tuesday.










And back on the topic of room treatments, I'm still SHOCKED at the bass I'm getting. It must be the room. I've been chasing this bass my whole life and figured that it just didn't exist in recorded music.

The kick drums & snares just kick you in the chest in every recording. There is that physical quality to drums that I've only heard with live drums.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9420#post_23126733
> 
> 
> Wisdom Audio. See my post above yours.
> 
> 
> Jeff



Totally agree with this btw. The Sage series blew my mind at RMAF. I've never had transients smack so hard, without sounding sharp. If I ever get a two-channel set up some day...they will be the Sage series line-source.


----------



## Jonny5nz

Hi guys, I have no real clue about sound treatments, and I'm wondering if it is even worth it in the room I am planning to turn into my HT.


The room has a large sliding door/window to the rear; a big window on one side wall; and a large open doorway on the other side wall. I was going to cover these areas with curtains and look at bass traps in the four corners. I was also going to put something on the walls for the first reflection and build a soffit with coffers as per the below pics.

 
 


With the limitations of the room (windows/doors etc.) is it even worth doing the bass traps? Any suggestions on limiting the bass going upstairs?


Thanks for your help.


----------



## steve71




> Quote:
> Originally Posted by *Jonny5nz*  /t/255432/acoustical-treatments-master-thread/9420#post_23162452
> 
> 
> Hi guys, I have no real clue about sound treatments, and I'm wondering if it is even worth it in the room I am planning to turn into my HT.
> 
> 
> The room has a large sliding door/window to the rear; a big window on one side wall; and a large open doorway on the other side wall. I was going to cover these areas with curtains and look at bass traps in the four corners. I was also going to put something on the walls for the first reflection and build a soffit with coffers as per the below pics.
> 
> 
> With the limitations of the room (windows/doors etc.) is it even worth doing the bass traps? Any suggestions on limiting the bass going upstairs?
> 
> 
> Thanks for your help.



I'm no expert (still learning lots), but the bass traps should be a no- brainier if you can sacrifice the room in the corners. OC 703 on the first reflections is also a good idea, but the windows might get in the way of that and you want the room to sound symmetrical. You can buy 6 or 12 sheets of 1"x2x4ft OC 703 online. Buy a box and start experimenting. You can just take the sheets out of the box and lean them up against the wall at the first reflection points. IIRC it's recommended to treat your entire screen wall.


If you really want to take it further, get some equipment to take measurements and pay attention to your rooms RT60.


Hope I got that right, but I sure someone will chime in and correct me if I didn't.










I just started experimenting in my room with a few boxes of OC 703 and the results are really amazing. Imaging is a LOT better and more uniform across the frequency spectrum. Mono recordings image dead center now. No strange shifts in tonal balance/ringing when playing at high volume and I can hear deep into the recording's noise foor / reverberations.


Good luck with your man cave!


----------



## Jonny5nz

Hi Steve, thanks for your advice. I don't really know what good sound sounds like. I will be getting an Onkyo amp so I hope that it's self calibration thingy can do the job.


----------



## Nightlord




> Quote:
> Originally Posted by *Jonny5nz*  /t/255432/acoustical-treatments-master-thread/9420#post_23171067
> 
> 
> Hi Steve, thanks for your advice. I don't really know what good sound sounds like. I will be getting an Onkyo amp so I hope that it's self calibration thingy can do the job.



Are there no other "nuts" in your area that you can visit? Building yourself an understanding of what good sound is and how far the boundaries can be pushed takes time and experience. Don't know how many times I've felt "it can't get much better than this" and I've pushed the envelope substantially since...


----------



## Jonny5nz

No, unfortunately I know of no nuts in my area. I'm guessing that appreciating quality sound is like appreciating fine wine or good coffee.


----------



## kertofer

Is treating the entire screen wall still considered the way to go? In my room I have standing super chunk style bass traps in all the corners but one (Too close to a door to put there) and have treated at the first reflection points. I have been thinking of building a psuedo wall out of 1X2's that I can use to hold some 2" OC703 and treating as much of the front wall as is realistic, but wanted to check and see what the thoughts are on how much return you see before putting the work into doing this.


Thoughts?


----------



## steve71




> Quote:
> Originally Posted by *Jonny5nz*  /t/255432/acoustical-treatments-master-thread/9420#post_23171067
> 
> 
> Hi Steve, thanks for your advice. I don't really know what good sound sounds like. I will be getting an Onkyo amp so I hope that it's self calibration thingy can do the job.



Positive improvements in sound should be obvious, but you could get a $100-$200 pair of headphone for reference. With that room you could do bass traps in the corners (floor to ceiling), treat the entire front wall (assuming you have an acoustically transparent screen) and try to get as many first reflection points as you can (search this thread for the mirror method). Make sure you get really heavy velvet drapes for those windows and you might even have to mirror the drapes on the other side of the room (without the window). Maybe some diffusion on the rear wall.


Look into what RT60 means. You want an RT60 value of 0.35-0.4 seconds. A measurement mic and software would be a good idea, but it all depends on how far you want to take it.


More on RT60 here: http://www.avsforum.com/t/332289/rt60-what-is-a-good-value 


Buy a couple of boxes of 1" thick 2ftx4ft Owens Corning 703 rigid fiberglass insulation. You should be able to mock up the bass traps and first reflection points in an afternoon. If you like what you hear, go ahead and DIY some nice looking room treatments (using the 703 you just bought).


----------



## steve71




> Quote:
> Originally Posted by *kertofer*  /t/255432/acoustical-treatments-master-thread/9420#post_23175227
> 
> 
> Is treating the entire screen wall still considered the way to go? In my room I have standing super chunk style bass traps in all the corners but one (Too close to a door to put there) and have treated at the first reflection points. I have been thinking of building a psuedo wall out of 1X2's that I can use to hold some 2" OC703 and treating as much of the front wall as is realistic, but wanted to check and see what the thoughts are on how much return you see before putting the work into doing this.
> 
> 
> Thoughts?



From what I've read so far in this thread - yes you want to treat the entire front wall. If you have an acoustically transparent screen, then use OC 703 as a first layer, but if your screen is acoustically reflective, then just treat the front wall for midbass/bass frequencies (where it's blocked by the screen).


----------



## pepar




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9420#post_23179429
> 
> 
> From what I've read so far in this thread - yes you want to treat the entire front wall. If you have an acoustically transparent screen, then use OC 703 as a first layer, but if your screen is acoustically reflective, then just treat the front wall for midbass/bass frequencies (where it's blocked by the screen).



I've read that as well, and did treat the entire cavity behind my AT screen/screenwall. But now that I am turning my attention to lengthening the decay time ... in my over-deadened room, I am eying that wall for some conversion from absorption to diffusion.


Jeff


----------



## Elill




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9420#post_23179706
> 
> 
> But now that I am turning my attention to lengthening the decay time ... in my over-deadened room,



Interesting - at what frequency band/range?


Have you tried covering it up with plastic first?


----------



## pepar




> Quote:
> Originally Posted by *Elill*  /t/255432/acoustical-treatments-master-thread/9420#post_23180667
> 
> 
> Interesting - at what frequency band/range?
> 
> 
> Have you tried covering it up with plastic first?



'Tis covered with 2" Linacoustic RC ...

Product thickness density 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC

Linacoustic RC 2" (51mm) 0.25 0.66 1.00 1.05 1.02 1.01 0.95


So removing some would help broadly ... above Schroeder. anyway, it's now covered floor to ceiling and I am considering removing that which is below the screen bottom. I'd speculate that would be all that I'd want to remove as there is still the reflections off the screen back that need attenuating. Make sense?


Jeff


----------



## Elill

If its the mid range you're talking about I'd just cover it in plastic at least this way you'll get some bass trapping and you wont have to go to the effort of taking it all down. If it works then you can tidy it up, if it doesn't you've just lost a few dollars in plastic sheet. Other option is cover in pegbaord.


I assume its mid-high you're worried about as I have been in very "lossy" rooms for bass and love it - in saying that it takes a little getting use to


----------



## Peter M




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9400_50#post_23179706
> 
> 
> I've read that as well, and did treat the entire cavity behind my AT screen/screenwall. But now that I am turning my attention to lengthening the decay time ... in my over-deadened room, I am eying that wall for some conversion from absorption to diffusion.
> 
> 
> Jeff



Hi Jeff,


If it was me I think I'd be looking to remove absorption from the side / rear walls and not the front wall. Just MHO.


Cheers,


----------



## pepar




> Quote:
> Originally Posted by *Elill*  /t/255432/acoustical-treatments-master-thread/9420#post_23181841
> 
> 
> If its the mid range you're talking about I'd just cover it in plastic at least this way you'll get some bass trapping and you wont have to go to the effort of taking it all down. If it works then you can tidy it up, if it doesn't you've just lost a few dollars in plastic sheet. Other option is cover in pegbaord.
> 
> 
> I assume its mid-high you're worried about as I have been in very "lossy" rooms for bass and love it - in saying that it takes a little getting use to



The plastic sheeting sounds like a good way to "audition" the change. For the bottom end, I am " well-trapped " with more to be installed in the rear to tame the remaining ringing.


Thanks,

Jeff


----------



## pepar




> Quote:
> Originally Posted by *Peter M*  /t/255432/acoustical-treatments-master-thread/9420#post_23181852
> 
> 
> Hi Jeff,
> 
> 
> If it was me I think I'd be looking to remove absorption from the side / rear walls and not the front wall. Just MHO.
> 
> 
> Cheers,



Thanks, I do have some "skylines" to swap for the rear 1st reflection point absorbers. (2" OC 703) But past that, removing my wall "treatment" gets messy. Below seated ear level, I have cheap "acoustical" carpet GLUED to the walls that I am loathe to touching. So, the rear treatment change I just mentioned, and maybe a 1D diffusor for the front ceiling FRP absorber are where I am looking.


Jeff


----------



## wse

I am looking for acoustic treatment that allow you to have your own pictures on it! I heard of several but though pricing was ridiculous


----------



## Spaceman




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9420#post_23184597
> 
> 
> I am looking for acoustic treatment that allow you to have your own pictures on it! I heard of several but though pricing was ridiculous


 http://www.avsforum.com/t/1316623/diy-custom-printed-movie-poster-acoustic-panels-cheap


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9420#post_23183416
> 
> 
> The plastic sheeting sounds like a good way to "audition" the change. For the bottom end, I am " well-trapped " with more to be installed in the rear to tame the remaining ringing.
> 
> 
> Thanks,
> 
> Jeff



Yes, I would suggest trying it out at first as well. I don't typically suggest to completely cover any wall with insulation unless the room is really large and needs it. The main point of treating the entire front wall that I see is that your sides and surround don't interfere with the mains. Definitely a good goal IMO - lets get the front information purely from the mains, and get the "surround" to "surround" us and not contort the front image. But this can of course be taken care of with many other types of treatment, not just absorption.


If you use plastic to try it out, try to get at least 10mil plastic to reflect some highs. Maybe consider trying double thickness so that it reflects some of the lower highs, maybe around 2kHz or so (as a general guess). Note that if you do place a decent amount of diffusion on the front wall, you don't necessarily have to remove the 2" insulation. Covering it with diffusion will simply help remove the over-absorption of high frequencies, while still giving you some decent midbass absorption, which is all well on the front wall IMO.


Lightweight diffusors or perhaps simple sequences of slats in front of the current absorption could help to scatter sound, give some diffusion, but still absorb some of the lower frequencies.


----------



## Jonny5nz




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9420#post_23179398
> 
> 
> Positive improvements in sound should be obvious, but you could get a $100-$200 pair of headphone for reference. With that room you could do bass traps in the corners (floor to ceiling), treat the entire front wall (assuming you have an acoustically transparent screen) and try to get as many first reflection points as you can (search this thread for the mirror method). Make sure you get really heavy velvet drapes for those windows and you might even have to mirror the drapes on the other side of the room (without the window). Maybe some diffusion on the rear wall.
> 
> 
> Look into what RT60 means. You want an RT60 value of 0.35-0.4 seconds. A measurement mic and software would be a good idea, but it all depends on how far you want to take it.
> 
> 
> More on RT60 here: http://www.avsforum.com/t/332289/rt60-what-is-a-good-value
> 
> 
> Buy a couple of boxes of 1" thick 2ftx4ft Owens Corning 703 rigid fiberglass insulation. You should be able to mock up the bass traps and first reflection points in an afternoon. If you like what you hear, go ahead and DIY some nice looking room treatments (using the 703 you just bought).



Thanks for the advice Steve.


----------



## Dennis Erskine

If your front speakers are either baffle mounted or less than 3.5' from the front/side walls, you'll need absorption or diffusion on that front wall.


----------



## sojodave

We just bought a new house and I decided (being the unselfish husband and father that I am) to take the biggest room in the house for home theater. After much debate, my wife convinced me to turn it into a home theater/multi purpose room by adding a kitchenette in the back. The room is finished and is 22' x 32' with 8' ceiling. It has a wicked echo and there is a column that is 10' from the screen wall and 7' from the side wall and a beam that runs the length of the room. I would like to acoustically treat this room, but I'm struggling to come up with a plan and I definitely need some help. Here is what I have so far.
I want to put up a fake wall on the front wall with OC703 or Duct Board across the entire front. Install corner trap in the right front corner, but there is a door in the other corner.
Corner traps in the back corner
Some type of acoustic panels or bass traps on the walls
Not sure, but maybe corner traps on both sides of beams
Some type of treatment on the ceiling with either bass traps or drop ceiling


Here is what the room looks like now.
 


Here is my layout.
 


Any suggestions?


----------



## wse




> Quote:
> Originally Posted by *sojodave*  /t/255432/acoustical-treatments-master-thread/9420#post_23192775
> 
> 
> We just bought a new house and I decided (being the unselfish husband and father that I am) to take the biggest room in the house for home theater. After much debate, my wife convinced me to turn it into a home theater/multi purpose room by adding a kitchenette in the back. The room is finished and is 22' x 32' with 8' ceiling. It has a wicked echo and there is a column that is 10' from the screen wall and 7' from the side wall and a beam that runs the length of the room. I would like to acoustically treat this room, but I'm struggling to come up with a plan and I definitely need some help. Here is what I have so far.
> I want to put up a fake wall on the front wall with OC703 or Duct Board across the entire front. Install corner trap in the right front corner, but there is a door in the other corner.
> Corner traps in the back corner
> Some type of acoustic panels or bass traps on the walls
> Not sure, but maybe corner traps on both sides of beams
> Some type of treatment on the ceiling with either bass traps or drop ceiling
> 
> Any suggestions?


Forget the Kitchen fridges make horrible noises and when they quick in suck up power. Great idea to take care of all accoustics for the room, might be worth getting some expert advice so you room is the best it can be. 

 

You can put a wicked screen in there


----------



## sojodave

Maybe I can make the fridge into one big bass trap...


----------



## mtbdudex

Just FYI,

It's been a long time since I looked at Bob Golds page for coefficients of various absorber materials.


He now has pink fluffy there!
http://www.bobgolds.com/AbsorptionCoefficients.htm 

(below copy/paste, looks better in html chart)


Owens Corning Fiberglass Batts (fluffy pink), on the wall, and 16" from the wall

Product thickness mounting 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC

Unfaced 2.5" R8 on wall 0.21 0.62 0.93 0.92 0.91 1.03 0.85

Unfaced 2.5" R8 16" air 0.59 0.84 0.79 0.94 0.96 1.12 0.90

Unfaced 3.5" R11 on wall 0.34 0.85 1.09 0.97 0.97 1.12 0.95

Unfaced 3.5" R11 16" air 0.80 0.98 1.01 1.04 0.98 1.15 1.00

Paper Out 3.5" R11 on wall 0.58 1.11 1.16 0.61 0.40 0.21 0.80

Unfaced 6.25" R19 on wall 0.64 1.14 1.09 0.99 1.00 1.21 1.05

Unfaced 6.25" R19 16" air 0.96 1.03 1.13 1.02 1.04 1.13 1.05

Paper Out 6.25" R19 on wall 0.94 1.33 1.02 0.71 0.56 0.39 0.90

Unfaced 12" on wall 1.14 1.09 1.09 0.99 1.00 1.21


----------



## wse

Question I never use the fireplace could it become a gigantic bass trap?


----------



## BIGmouthinDC

The actual interior dimension of the firebox and flue is not what I would consider "Giant", It is in the right location, Wall, floor intersection, so if it was stuffed with fiberglass and you had the right size opening it would have some impact.


----------



## wse




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/9450#post_23224231 The actual interior dimension of the firebox and flue is not what I would consider "Giant", It is in the right location, Wall, floor intersection, so if it was stuffed with fiberglass and you had the right size opening it would have some impact.


In the middle of the front wall?


----------



## steve71

I just don't see things going well at Christmas.


----------



## pepar




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9450#post_23229371
> 
> 
> I just don't see things going well at Christmas.



Bass trap = Santa trap?


----------



## erkq




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9450#post_23229371
> 
> 
> I just don't see things going well at Christmas.



Hahaha... how droll...


----------



## steve71

Thank you


----------



## GIK Acoustics




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9450#post_23222133
> 
> 
> Just FYI,
> 
> It's been a long time since I looked at Bob Golds page for coefficients of various absorber materials.
> 
> 
> He now has pink fluffy there!
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> (below copy/paste, looks better in html chart)
> 
> 
> Owens Corning Fiberglass Batts (fluffy pink), on the wall, and 16" from the wall
> 
> Product thickness mounting 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
> 
> Unfaced 2.5" R8 on wall 0.21 0.62 0.93 0.92 0.91 1.03 0.85
> 
> Unfaced 2.5" R8 16" air 0.59 0.84 0.79 0.94 0.96 1.12 0.90
> 
> Unfaced 3.5" R11 on wall 0.34 0.85 1.09 0.97 0.97 1.12 0.95
> 
> Unfaced 3.5" R11 16" air 0.80 0.98 1.01 1.04 0.98 1.15 1.00
> 
> Paper Out 3.5" R11 on wall 0.58 1.11 1.16 0.61 0.40 0.21 0.80
> 
> Unfaced 6.25" R19 on wall 0.64 1.14 1.09 0.99 1.00 1.21 1.05
> 
> Unfaced 6.25" R19 16" air 0.96 1.03 1.13 1.02 1.04 1.13 1.05
> 
> Paper Out 6.25" R19 on wall 0.94 1.33 1.02 0.71 0.56 0.39 0.90
> 
> Unfaced 12" on wall 1.14 1.09 1.09 0.99 1.00 1.21



Yes, very thick traps work well at low frequencies with pink fluffy. This is because the gas flow resistance of the material is quite low. The lower the resistance, the better for deep bass trapping. And thinner traps work better with higher air flow resistivity, so that's why Oc703 will work better at 2" for low frequencies than pink fluffy at 2".


----------



## SimpleTheater

Stupid question concerning http://www.bobgolds.com/AbsorptionCoefficients.htm 

It says 0.00 = no absorbtion.

0.50 = 50% absorbtion.

1.00 = 100% absorbtion.


So how can 701 plain have over 1.00 for every frequency from 250hz up? How can it absorb more than 100%?


----------



## HopefulFred

It can't. Numbers over 1 are theoretically impossible, but the measurement scheme leads to them anyway. Regardless, higher is more.


----------



## NicksHitachi

They are relative coefficients.


1.0 does not mean 100%


----------



## pepar




> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/9450#post_23239661
> 
> 
> They are relative coefficients.
> 
> 
> 1.0 does not mean 100%



Relative to what?


----------



## Dennis Erskine




> Quote:
> So how can 701 plain have over 1.00 for every frequency from 250hz up? How can it absorb more than 100%?



The coefficient is calculated based upon the face surface area of the material under test; however, while being tested the edges of the material are exposed which can result in coefficients greater than 1.


----------



## steve71

Since we are on the topic of pink fluffy stuff, is there an equation that relates the thickness of un-faced R19 and lowest frequency absorbed?


Or is a simple matter of needing X thickness where X = 1/4 wavelength?


I have a large space to work with, so I could potentially have 5ftx5ft bass traps in the corners. Obviously I will have to do some waterfall plots of the room to find out exactly which frequency's are creating standing waves and address them specifically. However, I was just curious about the formula.


----------



## steve71

I also wanted to add just how amazed I am with this OC 703 product. I've lined my room with 48 1" 2x4 panels and boy what a difference. But the most obvious thing is the noise floor of the recording. I'm hearing guitar amps buzzing, crowd noise, musicians cloths rubbing and feet shuffling. Breathing, sniffling and the natural acoustic of the hall (where present). It's kind of freaky to hear the hall noise and then to press pause. Your brain is expecting to hear the reverberation continue, but of course it does not.


----------



## pepar




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9450#post_23240745
> 
> 
> I also wanted to add just how amazed I am with this OC 703 product. I've lined my room with 48 1" 2x4 panels and boy what a difference. But the most obvious thing is the noise floor of the recording. I'm hearing guitar amps buzzing, crowd noise, musicians cloths rubbing and feet shuffling. Breathing, sniffling and the natural acoustic of the hall (where present). It's kind of freaky to hear the hall noise and then to press pause. Your brain is expecting to hear the reverberation continue, but of course it does not.



Be careful. It is easy to over-dampen a residential room.


Jeff


----------



## steve71




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9450#post_23240839
> 
> 
> Be careful. It is easy to over-dampen a residential room.
> 
> 
> Jeff



It just a mock setup for now with the 703 leaning up against the walls. To my ears it doesn't sound over-damped, but before committing to anything permanent I will be going off of measurements.


There's just so much to finalize before I can start taking meaningful measurements.


----------



## pepar

If you just cover, with the minimum required to do the job, all first reflection points, and put SSC bass traps in the corners (as many as you can), _most_ rooms will be OK.


Jeff


----------



## steve71




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9450#post_23240952
> 
> 
> If you just cover, with the minimum required to do the job, all first reflection points, and put SSC bass traps in the corners (as many as you can), _most_ rooms will be OK.
> 
> 
> Jeff



I could be wrong, but I think my room/speakers/setup will place the acoustics outside of most normal rooms.


It's a big space, a dedicated 30x40ft detached steel framed barn with cathedral ceilings. Right now the whole building is lined with 1ft fiberglass insulation and the exterior wall is 1/4" thick plywood.


The plan is to go with an 11 speaker setup & four horn subs. The speakers are constant directivity horns (large commercial speakers, Altec A6a's) which spread out a lot more HF energy than your typical cone and dome speakers which start beaming at high frequency.


----------



## pepar




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9450#post_23241073
> 
> 
> I could be wrong, but I think my room/speakers/setup will place the acoustics outside of most normal rooms.
> 
> 
> It's a big space, a dedicated 30x40ft detached steel framed barn with cathedral ceilings. Right now the whole building is lined with 1ft fiberglass insulation and the exterior wall is 1/4" thick plywood.
> 
> 
> The plan is to go with an 11 speaker setup & four horn subs. The speakers are constant directivity horns (large commercial speakers, Altec A6a's) which spread out a lot more HF energy than your typical cone and dome speakers which start beaming at high frequency.



Have you modeled the space? There are spreadsheets available online that can give you some idea what the acoustics will be like before it is built/complete.


If the entire INSIDE surface is covered with a foot of 'glass .... well that doesn't seem like it would sound good.


Jeff


----------



## steve71




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9450#post_23241097
> 
> 
> Have you modeled the space? There are spreadsheets available online that can give you some idea what the acoustics will be like before it is built/complete.
> 
> 
> If the entire INSIDE surface is covered with a foot of 'glass .... well that doesn't seem like it would sound good.
> 
> 
> Jeff



I haven't modeled the space. Might not be so easy with the cathedral ceilings and the space is not a rectangle as there's about 100sq/ft of bathroom and utility closet in one corner. Maybe ray tracing would be the way to go, but I guess I would have to pay big $ for that.


Right now I'm working my way through this thread and the Master Handbook of Acoustics.


Most of the insulation has dry wall in front of it, but in the ceiling the insulation is exposed. There is just so much to sort out before I'm even close to taking meaningful measurements.


Most of the interior need to be redone. Right now it's 1/2 guesthouse and 1/2 garage. I need to tear out the internal wall (non load bearing), remove the ceiling tiles from the guest house 1/2. Level the concrete slab and have a wood plank ceiling installed, remove the existing dry wall and run the appropriate wiring. Then I still have to redo some of the kitchen, move the door and electrical panel, remove the fireplace and figure out a heating solution.


Then I have to build a huge scope screen & four giant horn subs. Once all that's done, I can work on speaker placement and seating layout, mock it all up and start taking measurements while experimenting with absorption and diffusion. Once that's done it will be time to take everything out and finish the interior to look pretty. Somewhere in there I have to remove the garage door and put up a real wall in it's place.


All in all not much to do and I should have it ready next week


----------



## GIK Acoustics




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9450#post_23240706
> 
> 
> Since we are on the topic of pink fluffy stuff, is there an equation that relates the thickness of un-faced R19 and lowest frequency absorbed?
> 
> 
> Or is a simple matter of needing X thickness where X = 1/4 wavelength?
> 
> 
> I have a large space to work with, so I could potentially have 5ftx5ft bass traps in the corners. Obviously I will have to do some waterfall plots of the room to find out exactly which frequency's are creating standing waves and address them specifically. However, I was just curious about the formula.



Try out this calculator: http://www.stanleyhallstudios.co.uk/pacalc/ 

Select different models on the left for slightly different results. All of the methods used to calculate are all backed by theory and testing. I typically use Miki to model my results. The flow resistance of pink fluffy is roughly 5,000.


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9450#post_23238693
> 
> 
> Yes, very thick traps work well at low frequencies with pink fluffy. This is because the gas flow resistance of the material is quite low. The lower the resistance, the better for deep bass trapping. And thinner traps work better with higher air flow resistivity, so that's why Oc703 will work better at 2" for low frequencies than pink fluffy at 2".



So if I want to make a bass trap 84 x 34 x 7 what should I use. This is a soffit for a window that I never use! Also would covering it with 100% Linen thin fabri work?


----------



## steve71




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9450#post_23250040
> 
> 
> Try out this calculator: http://www.stanleyhallstudios.co.uk/pacalc/
> 
> Select different models on the left for slightly different results. All of the methods used to calculate are all backed by theory and testing. I typically use Miki to model my results. The flow resistance of pink fluffy is roughly 5,000.



Thanks, that link will be very helpful.


Plugging in the numbers it looks like 80-100hz is the best you can do with pink fluffy even if it's 8ft thick.


EDIT - I must have messed something up the first time. I'm now getting an absorption co-efficient of 0.6 to 0.8 from 20 to 80hz. Not bad at all for a 3ft deep bass trap


----------



## steve71




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9450#post_23256171
> 
> 
> So if I want to make a bass trap 84 x 34 x 7 what should I use. This is a soffit for a window that I never use! Also would covering it with 100% Linen thin fabri work?



You can plug in the number in the calculator linked in the posts above.


OC 703 has a flow resistivity of .......... 23,600 Pa.s/m2

Pink Fluffy has a flow resistivity of .......5,000 Pa.s/m2


At a thinness of 7" neither one will absorb much under 100hz.


Maybe try a HELMHOLTZ RESONATOR or absorption panels tuned to address problem areas?


Also bass will pass through fabric material, it's only the high frequencies that will be affected by your choice of covering.


----------



## wse




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9450#post_23256719
> 
> 
> You can plug in the number in the calculator linked in the posts above.
> 
> 
> OC 703 has a flow resistivity of .......... 23,600 Pa.s/m2
> 
> Pink Fluffy has a flow resistivity of .......5,000 Pa.s/m2
> 
> 
> At a thinness of 7" neither one will absorb much under 100hz.
> 
> 
> Maybe try a HELMHOLTZ RESONATOR or absorption panels tuned to address problem areas?
> 
> 
> Also bass will pass through fabric material, it's only the high frequencies that will be affected by your choice of covering.



Ok so if I use instead a corner and fill it with triangles 24 x 24 x 33.5 on the entire Hight of the ceiling 120" which means using 15 pannels of 703 (48x24). Will that work as a bass trap? Does that mean I can cover the bass trap with any material?


----------



## steve71




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9450#post_23256902
> 
> 
> Ok so if I use instead a corner and fill it with triangles 24 x 24 x 33.5 on the entire Hight of the ceiling 120" which means using 15 pannels of 703 (48x24). Will that work as a bass trap? Does that mean I can cover the bass trap with any material?



That won't do much under 100hz (according to the sim), but should be good for mid and upper bass. From playing with the calculator linked above, 24x24" pink fluffy will give you an absorption co-efficient between 0.5 and 0.85 from 20hz to 100hz. 36x36 would be even better for the low end. I have very limited real world experience with this stuff, I'm just passing along what the sim is telling me.


And yes, you can cover bass traps with any fabric material, without impacting their ability to absorb low bass.


----------



## wse

In order to be effective how thick do bass trap need to be?


----------



## steve71




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9450#post_23257189
> 
> 
> In order to be effective how thick do bass trap need to be?



2-3 feet thick to be effective below 100hz. You can click on the link above and play with the numbers and see for yourself how the thickness impacts the absorption co-efficient as a function of frequency.


It's worth noting the absorption isn't uniform in the 20-200hz range, so there is probably more to it than just stuffing the corners with insulation. You really need to measure your room to see what specific problems you have.


If you don't want to get technical, you can always buy a bunch of insulation rolls and stack them in the corners. If you like what you hear, then figure out a way to make them look pretty, or return them to the store and purchase some finished bass traps from one of vendors here.


----------



## localhost127




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9420_60#post_23256719
> 
> 
> OC 703 has a flow resistivity of .......... 23,600 Pa.s/m2


 http://www.gearslutz.com/board/8977246-post40.html


----------



## wse




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9480#post_23257264
> 
> 
> 2-3 feet thick to be effective below 100hz. You can click on the link above and play with the numbers and see for yourself how the thickness impacts the absorption co-efficient as a function of frequency. It's worth noting the absorption isn't uniform in the 20-200hz range, so there is probably more to it than just stuffing the corners with insulation. You really need to measure your room to see what specific problems you have. If you don't want to get technical, you can always buy a bunch of insulation rolls and stack them in the corners. If you like what you hear, then figure out a way to make them look pretty, or return them to the store and purchase some finished bass traps from one of vendors here.



2 to 3 feet right that's not going to happen


----------



## kertofer

Reading through this thread it appears that if you setup bass traps in the corner, such as what wse is asking about above, even if the trap is not large enough to absorb everything in one corner having all corners covered with smaller than ideal traps is going to help the room out a lot anyway. Each trap should absorb a certain amount of the bass, thus lowering the amount of reflections and standing waves.


Is this off base (No pun intended  ) ? It seems that doing less than ideal is still going to be helping more than doing nothing.


----------



## Brad Horstkotte

Right, it depends on where your problem areas are (frequency) and how severe - if not too low and not too severe, SuperChunks and other non-multi-foot-depth porous absorbers might be sufficient, if very low and severe, other options might work better - such as tuned absorbers. Before trying to attack with traps though, consider seating and sub placement.

http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/708542-10-5-r30-superchunk-build.html 

http://www.avforums.com/forums/room-acoustics-audio-video-calibration/1662218-super-chunk-absorber-test-cant-right.html 


(search the gearslutz site for more trap experiments and findings)


----------



## GIK Acoustics




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9480#post_23257264
> 
> 
> 2-3 feet thick to be effective below 100hz. You can click on the link above and play with the numbers and see for yourself how the thickness impacts the absorption co-efficient as a function of frequency.
> 
> 
> If you don't want to get technical, you can always buy a bunch of insulation rolls and stack them in the corners. If you like what you hear, then figure out a way to make them look pretty, or return them to the store and purchase some finished bass traps from one of vendors here.



They don't need to be nearly that thick. If you wanted them to have a coefficient of 1 under 100 Hz, then yes. Of course, 2-3 foot thick would work very well for very low frequencies but you can definitely get a great amount of absorption sub 100 Hz without such thick treatments. Our Soffit Trap tests to work well down to 50 Hz - you can check the testing reports on our website. Even a 6" panel in the corner works down to 80 Hz quite well.


The insulation rolls idea usually doesn't work very well either - the pink fluffy is extremely compressed in a bag, and it works well when its uncompressed and loose. Of course you might get some good action from it, but it would be hard to compare to anything and would likely give different results often.


Not tryin' to rip on your help, just don't want the wrong ideas floating around...


----------



## GIK Acoustics

So to better answer your question:


> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9450#post_23257189
> 
> 
> In order to be effective how thick do bass trap need to be?



This depends on how low you need to absorb


----------



## RossoDiamante


In thinking about using acoustic treatments on the walls of a theater room, is there some distance (either absolute or percentage) at which the presence of absorbers or diffusers on the back will not have any appreciable, beneficial audible effect?  In my example, I'd be about 13 feet from the front speakers and about 20 feet from the back wall.  The rear surrounds would be mounted in the ceiling about 8-9 feet behind the listening seat.


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9480#post_23267503
> 
> 
> So to better answer your question:
> 
> This depends on how low you need to absorb



I guess I need to take some measurement!


----------



## HopefulFred




> Quote:
> Originally Posted by *RossoDiamante*  /t/255432/acoustical-treatments-master-thread/9480#post_23268275
> 
> 
> In thinking about using acoustic treatments on the walls of a theater room, is there some distance (either absolute or percentage) at which the presence of absorbers or diffusers on the back will not have any appreciable, beneficial audible effect?  In my example, I'd be about 13 feet from the front speakers and about 20 feet from the back wall.  The rear surrounds would be mounted in the ceiling about 8-9 feet behind the listening seat.


With absorbers, you need not be concerned with your distance from them. With diffusers, there is such a thing as near-field and far-field. The waves of varying frequency need some space to come into reasonable homogeneity following their various interactions with the diffuser. Within the near-field, the sound field varies pretty greatly form place to place. I don't have the experience to tell you what will work, but I think I understand that you should ideally allow about three wavelengths distance from most diffusers. The wavelength in question is the lowest frequency diffused. This is for optimal effect - you may determine that far-field listening is not required for the benefits (like the attenuation of the specular reflection and improvement in decay times) to warrant the installation.


Most people will find that they end up in the near field of rear wall diffusers, but may install them anyway. You seem to have more rear space than most, so you may get better results than most.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9480#post_23268625
> 
> 
> With absorbers, you need not be concerned with your distance from them. With diffusers, there is such a thing as near-field and far-field. The waves of varying frequency need some space to come into reasonable homogeneity following their various interactions with the diffuser. Within the near-field, the sound field varies pretty greatly form place to place. I don't have the experience to tell you what will work, but I think I understand that you should ideally allow about three wavelengths distance from most diffusers. The wavelength in question is the lowest frequency diffused. This is for optimal effect - you may determine that far-field listening is not required for the benefits (like the attenuation of the specular reflection and improvement in decay times) to warrant the installation.
> 
> 
> Most people will find that they end up in the near field of rear wall diffusers, but may install them anyway. You seem to have more rear space than most, so you may get better results than most.



Excellent post, totally in agreeance here!


----------



## wse


Question have you ever tried those they look really cool, pricey but cool 

 

Art Diffuser Model W

 

http://www.acousticsfirst.com/diffuser-art-diffusor-model-w.htm


----------



## GIK Acoustics

Neat looking, but its periodicity shows that it's probably not a very good diffusor. A good scattering device sure, but I would recommend doing a typical 1D diffusor in a HT room on the back wall instead of a 2D or a skyline.


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9480#post_23269148 Neat looking, but its periodicity shows that it's probably not a very good diffusor. A good scattering device sure, but I would recommend doing a typical 1D diffusor in a HT room on the back wall instead of a 2D or a skyline.


1D what does it look like?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480#post_23269186
> 
> 
> 1D what does it look like?



Sorry to be cheeky and post a pic of one of our products, but it would be even weirder to link to a different company's diffusor so...

Here actually I'll just link to it instead of embedding the image:

[Removed the image myself to prevent further controversy]


A 1D diffusor diffuses in one dimension. So the above scatters and diffuses horizontally, but not vertically. A 2D diffusor (some people mistakenly call them a 3D diffusor) scatters in both the horizontal and vertical directions. In a room where listening position is constant, a 1D diffusor typically offers better performance per the space, cost, and weight. 2D diffusors are better suited for (IMO) recording studio where mic placement changes in height all the time. 2D diffusors can work well on the ceiling since spreading in the two different dimensions can be helpful, but I'd still rather use 1D in most circumstances.


----------



## localhost127




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23269148
> 
> 
> Neat looking, but its periodicity shows that it's probably not a very good diffusor. A good scattering device sure, but I would recommend doing a typical 1D diffusor in a HT room on the back wall instead of a 2D or a skyline.



+1


it appears that these companies now feel the need (requirement) to develop products that "differentiates" themselves from traditional diffusers - even though traditional (sic) reflection phase grating diffusers are concerned soley with the number theory and actual acoustical performance (equal energy lobes/dispersion) - not with what "looks cool".


does that company provide polars across a given bandwidth for these "diffusers" (sic)?



> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23269111
> 
> 
> Question have you ever tried those they *look really cool*, pricey but cool



you're exactly the type this company is marketing to.


if you're interested: http://www.subwoofer-builder.com/qrdude.htm 


and collo wrote a wonderful user guide easily digestable for the novice: http://www.subwoofer-builder.com/qrd.htm


----------



## wse




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9480#post_23269984
> 
> 
> +1 it appears that these companies now feel the need (requirement) to develop products that "differentiates" themselves from traditional diffusers - even though traditional (sic) reflection phase grating diffusers are concerned soley with the number theory and actual acoustical performance (equal energy lobes/dispersion) - not with what "looks cool". does that company provide polars across a given bandwidth for these "diffusers" (sic)? *you're exactly the type this company is marketing to*.
> 
> if you're interested: http://www.subwoofer-builder.com/qrdude.htm and collo wrote a wonderful user guide easily digestable for the novice: http://www.subwoofer-builder.com/qrd.htm



Interesting links, I love the fact that I am exactly the type, am not sure what that means but anyway, if I didn't know better I would take this as an insult!


I also love the fact that there is no conflict of interest, oh this is crap you buy this and by the way we sell it as well! I love it when people push their own products on site like this it becomes a disguised commercial! Well I guess I need to educate myself so I am not "one of these types"


----------



## kertofer

Everyone stay calm...


----------



## localhost127




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23270212
> 
> 
> I also love the fact that there is no conflict of interest, oh this is crap you buy this and by the way we sell it as well! I love it when people push their own products on site like this it becomes a disguised commercial! Well I guess I need to educate myself so I am not "one of these types"



is this a joke? pushing their own products? are you implying QRDude is a "product for sale"? ??

where is this "conflict of interest"? *you were linked to a site of which you can utilize the free software to construct your own phase grating (QRD) based on your own personal criteria or restraints.*


QRDude is a free software tool and the included (well written) technical guide is well written and easily digestible for the novice.


there are "commercial products" of QRDs and PRDs because, as you may or may not find out, construction can be tedious and incredibly time consuming. multiply by however-many-units-you-need, and it can become overwhelming. some people will "pay" for the service of a pre-constructed device. you were linked to resources of which you could construct your own.


the product you originally linked to is just a laughable concept of audio marketing. where are the polars for that product? but it does "look cool". when in doubt, ignore the physics and go with what looks coolest.


----------



## wse

GIK is pushing their own products please!


----------



## Brad Horstkotte

I don't see it that way at all. There is science behind the design of diffusors, and the design that was posted does not adhere to the science. Could you get some diffusion with it? Sure. You could with a bookcase too. But it wouldn't work as well as those designed as a true quadratic residue diffusor, per qrdude model + DIY, or per the GIK product that was posted, which was posted as an example. There are other commercial implementations available too, just search for QRD.


More info - http://www.hunecke.de/en/knowledge/diffusors/qrd.html 


Personally I think the pros that share info on this thread generally do a great job of sharing knowledge without turning into a sales pitch. Keep it up!


----------



## giomania




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9500_100#post_23274621
> 
> 
> Personally I think the pros that share info on this thread generally do a great job of sharing knowledge without turning into a sales pitch. Keep it up!



+1


----------



## djkest

I don't think GIK Acoustics crossed the line. They were giving an example of a scientifically designed diffuser. They didn't tell you to buy it. They offer a lot of good information to people for free and don't ask for anything in return.


I found the rest of their post informative and I think that persuaded me to make my own 1D diffuser for my back wall (I was going to make a 2D diffuser) DIY once I have the time.


BTW forget everything you know and just get THIS:


----------



## localhost127




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23274410
> 
> 
> GIK is pushing their own products please!



they sell a QRD - it is not really "their product" ... you're paying for the construction and materials. the number theory to design the product is well known and not "theirs".

i linked you to a host of resources such that you could design the very same "product" - if you were so inclined.


this is in contrast to the product you linked to that is essentially a scatterer with unpublished polars and data -- being "pushed" (marketed) as a "diffuser". quite a different scenario!


you should really take some time to understand what is being discussed, as what i was addressing seems to be lost on you.

if you're interested, check out the QRDude tech guide i linked to as well as the software itself (play around with it).


also,
http://www.rpginc.com/docs%5CTechnology%5CPresentations%5CMRS%20Online.pdf


----------



## pepar




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480#post_23274410
> 
> 
> GIK is pushing their own products please!



A day or two ago I thought I should praise Alexander for his sharing of knowledge, but I didn't and the moment passed. I will now correct that and express my opinion that I appreciate his - and every other pro's - contributions. Well, DUH!, of course when an example of a product is needed he will link his own. that doesn't diminish his contributions and it certainly doesn't raise my hackles.


Jeff


----------



## A9X-308




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9400_100#post_23274410
> 
> 
> GIK is pushing their own products please!


What a load of crap. You got your question answered, and to illustrate that answer GIK showed a product they make and clearly declared that. What was he supposed to do, make a drawing that showed the same thing to appease your delicate sensibilities?


Then note that you were given the info to roll your own basically for free (well, materials and time) if you so desired, as well as learn more about the subject.


----------



## Mr.Tim

GIK and bpape have always been above board and helpful.


You asked a question, he answered it. I don't see any issue, especially when it is clear that he is affiliated with the company.


Tim


----------



## wse




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9480#post_23275003
> 
> 
> they sell a QRD - it is not really "their product" ... you're paying for the construction and materials. the number theory to design the product is well known and not "theirs".
> 
> i linked you to a host of resources such that you could design the very same "product" - if you were so inclined.
> 
> 
> this is in contrast to the product you linked to that is essentially a scatterer with unpublished polars and data -- being "pushed" (marketed) as a "diffuser". quite a different scenario!
> 
> 
> you should really take some time to understand what is being discussed, as what i was addressing seems to be lost on you.
> 
> if you're interested, check out the QRDude tech guide i linked to as well as the software itself (play around with it).
> 
> 
> also,
> http://www.rpginc.com/docs%5CTechnology%5CPresentations%5CMRS%20Online.pdf


Great link I love math!


----------



## wse

I didn't know so many were on the payroll or on the take, objectivity, and disclosure of conflict of interest is always helpful that's all sorry I am a bit of a contrarian and don't always drink the cool aid!


----------



## Brad Horstkotte

Yes, everyone but you has ulterior motives


----------



## pepar




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480#post_23277150
> 
> 
> I didn't know so many were on the payroll or on the take, objectivity, and disclosure of conflict of interest is always helpful that's all sorry I am a bit of a contrarian and don't always drink the cool aid!



What are those items that appear in your sig? Are you selling those?










Jeff


----------



## erkq




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480#post_23277150
> 
> 
> I didn't know so many were on the payroll or on the take, objectivity, and disclosure of conflict of interest is always helpful that's all sorry I am a bit of a contrarian and don't always drink the cool aid!



Indeed... so much Kool-Aid in this thread for sure... not.


----------



## wse




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9480#post_23277327 Yes, everyone but you has ulterior motives


Ulterior motives!


----------



## wse




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9510#post_23278118 What are those items that appear in your sig? Are you selling those?
> 
> 
> 
> 
> 
> 
> 
> Jeff


Why are you buying!


----------



## steve71




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9480#post_23267476
> 
> 
> They don't need to be nearly that thick. If you wanted them to have a coefficient of 1 under 100 Hz, then yes. Of course, 2-3 foot thick would work very well for very low frequencies but you can definitely get a great amount of absorption sub 100 Hz without such thick treatments. Our Soffit Trap tests to work well down to 50 Hz - you can check the testing reports on our website. Even a 6" panel in the corner works down to 80 Hz quite well.
> 
> 
> The insulation rolls idea usually doesn't work very well either - the pink fluffy is extremely compressed in a bag, and it works well when its uncompressed and loose. Of course you might get some good action from it, but it would be hard to compare to anything and would likely give different results often.
> 
> 
> Not tryin' to rip on your help, just don't want the wrong ideas floating around...



Thanks for the correction GIK! Like I said, I have no practical experience just going off the sim. Your help and help from the other experts in this thread is invaluable!!


I did notice that above 500hz OC703 gives a absorption coefficient of ~ 1 which is obviously desirable. Why is that under 100hz, an absorption coefficient well below 1 is acceptable?


Also, I bought a ton of OC R30 pink fluffy (un-faced) to experiment with. I can't return it once I take it out of the bag. Any reason why R30 shouldn't be used? I didn't see it listed in the charts (see below) as it only went up to R-19. The only unfaced suff Home Depot had was the R30?


Owens Corning Fiberglass Batts (fluffy pink), on the wall, and 16" from the wall

Product thickness mounting 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC

Unfaced 2.5" R8 on wall 0.21 0.62 0.93 0.92 0.91 1.03 0.85

Unfaced 2.5" R8 16" air 0.59 0.84 0.79 0.94 0.96 1.12 0.90

Unfaced 3.5" R11 on wall 0.34 0.85 1.09 0.97 0.97 1.12 0.95

Unfaced 3.5" R11 16" air 0.80 0.98 1.01 1.04 0.98 1.15 1.00

Paper Out 3.5" R11 on wall 0.58 1.11 1.16 0.61 0.40 0.21 0.80

Unfaced 6.25" R19 on wall 0.64 1.14 1.09 0.99 1.00 1.21 1.05

Unfaced 6.25" R19 16" air 0.96 1.03 1.13 1.02 1.04 1.13 1.05

Paper Out 6.25" R19 on wall 0.94 1.33 1.02 0.71 0.56 0.39 0.90

Unfaced 12" on wall 1.14 1.09 1.09 0.99 1.00 1.21


----------



## steve71




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480#post_23274410
> 
> 
> GIK is pushing their own products please!



I don't see anything wrong. GIK is dishing out tons of FREE help and you insult him


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9510#post_23278811
> 
> 
> Why is that under 100hz, an absorption coefficient well below 1 is acceptable?



It is desireable, its just that to be that effective at low frequencies requires a lot of depth, and most people don't want to trade off that much room for the extra absorption.


> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9510#post_23278811
> 
> 
> Any reason why R30 shouldn't be used?



Nope, its the same stuff, just thicker.


----------



## wse




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9510#post_23278841
> 
> 
> I don't see anything wrong. GIK is dishing out tons of FREE help and you insult him



No insults just saying when a sales man gives advice it is usually not unbiased!


----------



## pepar

Ok folks, move along. Nothing to see here.


Jeff


----------



## wse

Sounds good


----------



## localhost127




> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23278811
> 
> 
> I did notice that above 500hz OC703 gives a absorption coefficient of ~ 1 which is obviously desirable. Why is that under 100hz, an absorption coefficient well below 1 is acceptable?



wouldn't it be more logical to question why coefficients _above_ 1 are "acceptable" - and just "how" this can be? - and to understand such figures are not a "percentage absorbed"?


but all things considered, remember that for LF porous absorbers used to address modal issues ... there will be multiple passes of the wave through the absorber as the energy is a _persisted resonance_ (unlike a front wall SBIR LF absorber or other broadband absorber for indirect specular reflections that only get "one shot" at properly attenuating the signal).


----------



## pepar




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9510#post_23280466
> 
> 
> 
> but all things considered, remember that for LF porous absorbers used to address modal issues ... there will be multiple passes of the wave through the absorber as the energy is a _persisted resonance_ (unlike a front wall SBIR LF absorber or other broadband absorber for indirect specular reflections that only get "one shot" at properly attenuating the signal).



Sure, porous LF absorbers don't "trap" the LF so much as bleed off its energy reducing ringing/overhang


Jeff


----------



## RossoDiamante


In thinking about acoustically treating my future theater room, I'm planning on 1" absorptive material (Linacoustic?) and diffusive material (???) behind a stretched fabric wall of some sort.  Does the fabric used in front of these absorbers need to be acoustically transparent?  Obviously, in those areas where the fabric will cover my in-wall speakers, the fabric will have to be acoustically transparent, but does it make any difference for the 95% of the wall that have no speakers?


----------



## wse

So how about these are they charlatans as well http://www.vicousticusa.com 


They look very nice, any one used them?


----------



## HopefulFred

Yes, it makes a difference.


Diffusors will absorb slightly - think of the sound waves moving within them as encountering friction. The extra surfaces within a fabric means more absorption. It's not huge, but it's measurable. In some cases, the fabric might also generate diaphragmatic action that could absorb significantly in a narrow range of frequencies. If the goal of diffusion is to redirect reflected sounds without loosing the sonic energy, the absorption is counterproductive.


In response to your question marks - you won't find a diffusive material. You'll need to buy or build a structure with very specific shapes and sizes. (Maybe you already knew that, but I don't want you to think that a diffusor is a simple as a piece of foam or something.)


----------



## RossoDiamante


On a related note, in browsing the Guilford of Maine web site, there is a whole line of what the term "Acoustic Fabrics".  It seems that the gold standard according to AVS forum is the FR-701 style.  It appears to have very little effect between 250-1000 Hz with a gradual rolloff at the higher frequencies.

 

 



 

What would one expect with some of the other fabrics in the GOM Acoustic linup?  I'm looking at their Anchorage product.  If I'm interpreting their performance graphs correctly, it appears that this fabric seems to have more attenuation across the frequency band and a little more relative attenuation at the higher frequencies compared to the FR-701.  Can this sort of performance difference be compensated for by level adjustments and mild equalization of those speakers that lie behind this fabric?

 

 



 

Other fabrics of interest are their Sensa and Coastline styles.  Sensa appears to have even better acoustical performance than the FR-701 below 250Hz, but still has the high-frequency rolloff as seen in the FR-701 graph.  The Coastline style, in contrast, seems to  have more attenuation, but at a more linear pattern across the frequency spectrum which to my mind seems like it would be more amenable to simple level adjustments as opposed to level and equalization adjustments.  Are my interpretations of these data graphs accurate?  Is my characterization of the types of adjustments that could be made to optimize the acoustic performance of these fabrics in a typical HT application valid?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9480#post_23274410
> 
> 
> GIK is pushing their own products please!



Hi WSE,


Sorry you feel that way. I purposely uploaded the pic to AVS' forums so it was simply a link to a picture that was actually hosted here on AVS, not on our site. I removed the image. If you want other pictures of a 1D vs a 2D diffusor, please feel free to Google image search for them. In either case, I've removed the image. I figured it was in bad taste when I originally posted it but I felt the disclaimer I made would help - I guess not.

Thanks.


--

To others, thanks, but it's not necessary to defend my position in the thread. If someone feels a certain way, you explaining how you feel differently usually won't change how they feel or interpret a message.


Back on track to the thread:


> Quote:
> Originally Posted by *steve71*  /t/255432/acoustical-treatments-master-thread/9510#post_23278811
> 
> 
> Thanks for the correction GIK! Like I said, I have no practical experience just going off the sim. Your help and help from the other experts in this thread is invaluable!!
> 
> 
> I did notice that above 500hz OC703 gives a absorption coefficient of ~ 1 which is obviously desirable. Why is that under 100hz, an absorption coefficient well below 1 is acceptable?
> 
> 
> Also, I bought a ton of OC R30 pink fluffy (un-faced) to experiment with. I can't return it once I take it out of the bag. Any reason why R30 shouldn't be used? I didn't see it listed in the charts (see below) as it only went up to R-19. The only unfaced suff Home Depot had was the R30?
> 
> 
> Owens Corning Fiberglass Batts (fluffy pink), on the wall, and 16" from the wall
> 
> Product thickness mounting 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
> 
> Unfaced 2.5" R8 on wall 0.21 0.62 0.93 0.92 0.91 1.03 0.85
> 
> Unfaced 2.5" R8 16" air 0.59 0.84 0.79 0.94 0.96 1.12 0.90
> 
> Unfaced 3.5" R11 on wall 0.34 0.85 1.09 0.97 0.97 1.12 0.95
> 
> Unfaced 3.5" R11 16" air 0.80 0.98 1.01 1.04 0.98 1.15 1.00
> 
> Paper Out 3.5" R11 on wall 0.58 1.11 1.16 0.61 0.40 0.21 0.80
> 
> Unfaced 6.25" R19 on wall 0.64 1.14 1.09 0.99 1.00 1.21 1.05
> 
> Unfaced 6.25" R19 16" air 0.96 1.03 1.13 1.02 1.04 1.13 1.05
> 
> Paper Out 6.25" R19 on wall 0.94 1.33 1.02 0.71 0.56 0.39 0.90
> 
> Unfaced 12" on wall 1.14 1.09 1.09 0.99 1.00 1.21



Unfaced 12" is R38, so you could imagine R30 to be between R19 and R38 absorption coefficients. They all absorb well at large thicknesses as you can see.


Most absorbers simply can not give absorption coefficients below 100 Hz that are at a 1. Tuned absorbers can hit at an absorption coefficient of 1 under 100 Hz, but porous absorbers just have to be too large. And the sabines themselves are important too - if an absorber gives you 10 sabines at 50 Hz, then 4 of them is going to give you 40 sabines at 50 Hz. So it becomes a question of would you rather have a 4' thick absorber or four 1' thick absorbers? This is a completely arbitrary set of thicknesses but the point is the actual coefficient isn't the most important factor, but sabines per size of the absorber. If making your absorber an extra 2' thick only gives you an extra 5 sabines at some frequency, it isn't really worth it.


----------



## Nyal Mellor




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9480#post_23269984
> 
> 
> does that company provide polars across a given bandwidth for these "diffusers" (sic)?



Right here: http://www.acousticsfirst.com/docs/AcousticsFirst_Art_Diffusor.pdf


----------



## GIK Acoustics




> Quote:
> Originally Posted by *RossoDiamante*  /t/255432/acoustical-treatments-master-thread/9510#post_23286029
> 
> 
> In thinking about acoustically treating my future theater room, I'm planning on 1" absorptive material (Linacoustic?) and diffusive material (???) behind a stretched fabric wall of some sort.  Does the fabric used in front of these absorbers need to be acoustically transparent?  Obviously, in those areas where the fabric will cover my in-wall speakers, the fabric will have to be acoustically transparent, but does it make any difference for the 95% of the wall that have no speakers?



Could you be more descriptive with "diffusive material" please? There isn't really diffusive material like there is absorptive material. You'd need to use wood, EPS, some sort of hard material to be sure it's reflecting and not absorbing, and you want to build it with a specific pattern in mind. You can always do slats in front of the absorptive material to add diffusion. Depending on the type of wood used, you could hide it behind the fabric or you can expose it in front of the fabric.

If you had diffusive elements, you'd want any cloth covering it to be as transparent as possible.

The acoustic transparency of cloth helps so that more sound gets absorbed by the material behind the fabric. A lot of fabrics are tighter weaved and so while sound hitting the fabric dead on at 0 degrees will probably still get absorbed by most fabrics, they'll start reflecting at other angles of incidence. If you purposely put absorbers in a position and then use a fabric that's partially reflective, you're _sort of_ negating putting absorbent behind them.

Of course this is all only by little amounts, it's not entirely detrimental to use a different cloth, most of the sound will still be absorbed either way.


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9510#post_23288278 Hi WSE, Sorry you feel that way. I purposely uploaded the pic to AVS' forums so it was simply a link to a picture that was actually hosted here on AVS, not on our site. I removed the image. If you want other pictures of a 1D vs a 2D diffusor, please feel free to Google image search for them. In either case, I've removed the image. I figured it was in bad taste when I originally posted it but I felt the disclaimer I made would help - I guess not. Thanks.
> --
> 
> To others, thanks, but it's not necessary to defend my position in the thread. If someone feels a certain way, you explaining how you feel differently usually won't change how they feel or interpret a message.


Thank you, greatly appreciate, it shows integrity!


----------



## wse











 

Diffusion


----------



## GIK Acoustics

By the way WSE, you'll notice that in the post on the the other page when I was recommending against using 2D diffusors, it was for the back wall.

2D diffusors scatter in two directions. If you're facing one head on, they diffuse in the horizontal and vertical directions.

The ceiling is a good place for 2D diffusors if they are used since they will diffuse sound in both horizontal directions, which is useful when you have multiple seating positions. On the side walls or back wall, there's not a lot of reasons to diffuse in the vertical direction unless it's a recording room where things are often at a variable height. In a listening room or a home theater (or even a control room) we're pretty much in one place vertically always, so a 1D diffusor is usually better suited for the room. 1D diffusors also usually have a greater possibility to have thicker and/or wider wells, so the bandwidth is typically stronger than most 2D diffusors. This is why I, and others, usually suggest 1D diffusion on the back wall of a home theater room.


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9510#post_23288540  By the way WSE, you'll notice that in the post on the the other page when I was recommending against using 2D diffusors, it was for the back wall.  2D diffusors scatter in two directions. If you're facing one head on, they diffuse in the horizontal and vertical directions.
> 
> The ceiling is a good place for 2D diffusors if they are used since they will diffuse sound in both horizontal directions, which is useful when you have multiple seating positions. On the side walls or back wall, there's not a lot of reasons to diffuse in the vertical direction unless it's a recording room where things are often at a variable height. In a listening room or a home theater (or even a control room) we're pretty much in one place vertically always, so a 1D diffusor is usually better suited for the room. 1D diffusors also usually have a greater possibility to have thicker and/or wider wells, so the bandwidth is typically stronger than most 2D diffusors. This is why I, and others, usually suggest 1D diffusion on the back wall of a home theater room.


I see, thank you.

 

So I read that having a book case in the back is a good idea?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9510#post_23288585
> 
> 
> I see, thank you.
> 
> 
> So I read that having a book case in the back is a good idea?



Large pieces of furniture, like bookcases, can cause stereo imbalances if they're on the sidewalls close to listening position, so usually if they have to stay in the room, it's best to have them on the back wall. However, the whole 'bookshelves diffusive' thing is a myth - books are partially absorptive first off, but a diffusor is not simply just "random" widths and depths. There is a lot of calculation, typically using pseudo-random sequences to generate a decent or better diffusor.


Jeff Hedback actually wrote up a great article on diffusion for us, you can check it out here: http://gikacoustics.com/diffusion-by-jeff-hedback/ - explains a lot of the principals behind diffusion and why they're important. Of course, if you wish to get in depth on the matter and learn the physics behind, there's always Cox & D'Antonio's Acoustic Absorbers and Diffusers: Theory, Design and Application


----------



## BasementBob




> Quote:
> Originally Posted by *SimpleTheater*  /t/255432/acoustical-treatments-master-thread/9450#post_23239577
> 
> 
> Stupid question concerning http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> It says 0.00 = no absorbtion.
> 
> 0.50 = 50% absorbtion.
> 
> 1.00 = 100% absorbtion.
> 
> 
> So how can 701 plain have over 1.00 for every frequency from 250hz up? How can it absorb more than 100%?



The next two paragraphs, same page, explain that published coefficients are not percentages.


(as opposed to Sabine's reverberation equation, which defines the absorption coefficient of a material is a number between 0 and 1 which indicates the proportion of sound which is absorbed by the surface compared to the proportion which is reflected back into the room. A (perfectly) large, fully open window would offer no reflection as any sound reaching it would pass straight out and no sound would be reflected. This would have an absorption coefficient of 1. Conversely, a thick, smooth painted concrete ceiling would be the acoustic equivalent of a mirror, and would have an absorption coefficient very close to 0.)


----------



## localhost127




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23288298
> 
> 
> Right here: http://www.acousticsfirst.com/docs/AcousticsFirst_Art_Diffusor.pdf



im quite confused as to how their 15"x15" (9" depth) device offers bandwidth down to 125hz (which corresponds to wavelength of *9ft*!).
























where do their diffusion coefficients come from?


----------



## Nyal Mellor




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9510#post_23292734
> 
> 
> im quite confused as to how their 15"x15" (9" depth) device offers bandwidth down to 125hz (which corresponds to wavelength of *9ft*!).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> where do their diffusion coefficients come from?



testing?


----------



## pepar

How novel.


----------



## Roger Dressler

Tool's book states:


> Quote:
> Gilford (1959) describes some BBC experiments in which they concluded that to be effective, projections from walls must be 1/7-wavelength or greater. This means that to address voice resonances (100+ Hz), they must be of the order of 20 in. (50 cm) deep.


----------



## localhost127




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23293780
> 
> 
> testing?



testing against what standard, exactly? they list: _Type A test per ASTM C 423-02, E400 test per ASTM E 795-00_ - but nothing re: diffusion coefficient.


Model F is *2" deep* and yet has a "diffusion coefficient" of *0.79* at *125hz!!*


2" depth against a 9ft wavelength; am i missing something?


----------



## localhost127




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9480_60#post_23294984
> 
> 
> Tool's book states:



no need to guess - BEM simulation is quite sufficient via that of AFMG Reflex (free for 30-day trial): http://reflex.afmg.eu/index.php/rf-features-en.html


----------



## GIK Acoustics




> Quote:
> Originally Posted by *localhost127*  /t/255432/acoustical-treatments-master-thread/9510#post_23292734
> 
> 
> im quite confused as to how their 15"x15" (9" depth) device offers bandwidth down to 125hz (which corresponds to wavelength of *9ft*!).
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> where do their diffusion coefficients come from?



I wondered this as well - obviously the size limits this from being possible. It's also worth mentioning that the Model E boasts high diffusion coefficients at 125 Hz even though its polystyrene...I mean, can EPS really be reflective at 125 Hz? Maybe it can, I'm not sure honestly.



> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9510#post_23293780
> 
> 
> testing?



According to the product spec sheet, the _absorption_ was tested in accordance with ISO standards but they did not list whether the diffusion coefficients were tested or calculated.


----------



## Mfusick

So this thread is from 2003 with 100 pages+ so I am guessing I probably should not have to read all of it. Anyone want to give me cliff notes or aware me ?


I'm looking to start a new construction theater (above 2.5 car garage) and I can control pretty much everything since I have not started yet. Construction starts in a few months. Is there a generally best practice process or product combo for sound treatment ?


What is ideal (based on high value) ? Is there a certain process or product I should be considering or planning for in a moderate middle class budget theater build ?


----------



## Mr.Tim




> Quote:
> Originally Posted by *Mfusick*  /t/255432/acoustical-treatments-master-thread/9540#post_23334516
> 
> 
> So this thread is from 2003 with 100 pages+ so I am guessing I probably should not have to read all of it. Anyone want to give me cliff notes or aware me ?
> 
> 
> I'm looking to start a new construction theater (above 2.5 car garage) and I can control pretty much everything since I have not started yet. Construction starts in a few months. Is there a generally best practice process or product combo for sound treatment ?
> 
> 
> What is ideal (based on high value) ? Is there a certain process or product I should be considering or planning for in a moderate middle class budget theater build ?



You can read any one of the build threads in the Dedicated Theater Design forum to see the methods employed. Refer back to this thread if you have questions on specific methodology. Once you have a general idea of what you want to accomplish, start a thread with specific questions.


Beyond that, if you don't have the time to invest in research you can contact a design firm (eg Erskine Design is a popular firm here) that will lay out exactly what you need to do.


Tim


----------



## Willie

Think it is foolish not to invest in the time to read this thread. This thread is a convergence of best practices, science, and the invaluable experience of those who have designed and built their own home theaters. It includes the input of many design and audio professionals who graciously share the knowledge that earns them a living. Why would you not want to read it?


A cliff notes version would be akin to a fast food approach to home theater acoustics.


----------



## Mfusick




> Quote:
> Originally Posted by *Willie*  /t/255432/acoustical-treatments-master-thread/9500_50#post_23335450
> 
> 
> Think it is foolish not to invest in the time to read this thread. This thread is a convergence of best practices, science, and the invaluable experience of those who have designed and built their own home theaters. It includes the input of many design and audio professionals who graciously share the knowledge that earns them a living. Why would you not want to read it?
> 
> 
> A cliff notes version would be akin to a fast food approach to home theater acoustics.




I've been skimming and pretty much come to the same conclusion on my own.


I'm not afraid of doing the reading and research; the bigger concern was the beginning of this thread was 10 years ago. My concern was new products, technologies and practices might have developed after that time so I'm wondering if its outdated, or still viable. 10 years ago I was hanging out in the RPTV forum. Lol. Today I'm more into HTPCs but back when this thread started a PC couldn't even play 1080p video.


Its hard as a newb to figure out where the line is I should start. I was just looking for general advice on that regard. I guess I'll just read the thread backwards ????


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Mfusick*  /t/255432/acoustical-treatments-master-thread/9540#post_23335471
> 
> 
> I've been skimming and pretty much come to the same conclusion on my own.
> 
> 
> I'm not afraid of doing the reading and research; the bigger concern was the beginning of this thread was 10 years ago. My concern was new products, technologies and practices might have developed after that time so I'm wondering if its outdated, or still viable. 10 years ago I was hanging out in the RPTV forum. Lol. Today I'm more into HTPCs but back when this thread started a PC couldn't even play 1080p video.
> 
> 
> Its hard as a newb to figure out where the line is I should start. I was just looking for general advice on that regard. I guess I'll just read the thread backwards ????



That could be a start, though a lot of people come into this thread with very specific questions and often times you won't know the context it's in. This thread is often jumped in for people to ask some simple questions instead of a whole host of where to start for a theater - for the latter you'd be better of with a dedicated thread when you've got the time.

As for best practices, some things differ by designers but there is a few things you'll want to look into, and that is reducing the reverberation and absorbing modes down to at least 125 Hz (roughly the cut off for male voice) to improve dialogue clarity, down lower than that if you want an accurate response for music. Many theaters employ a second subwoofer to 'fill in' dips in response. Treatment can be multipurpose (clouds with recessed lighting built in or risers with bass trapping built in) or can be hidden behind a wall of fabric. Often times the entire front wall is absorbed so that your surrounds don't reflect and come from the front of the room. Really there are a lot of things to address and we've hardly got information from you - how many speaker set up, what size do you have to work with, is isolation necessary, size of projector, etc etc..probably best for its own thread as there are a lot of things you'll address as you go along. You can read up on some of the general ideas here - most of it is geared towards a music room and not a theater, but the same principals apply: http://gikacoustics.com/acoustic-primer/ 
Let me know if you have any specific questions!


----------



## pepar




> Quote:
> Originally Posted by *Mfusick*  /t/255432/acoustical-treatments-master-thread/9540#post_23335471
> 
> 
> I've been skimming and pretty much come to the same conclusion on my own.
> 
> 
> I'm not afraid of doing the reading and research; the bigger concern was the beginning of this thread was 10 years ago. My concern was new products, technologies and practices might have developed after that time so I'm wondering if its outdated, or still viable. 10 years ago I was hanging out in the RPTV forum. Lol. Today I'm more into HTPCs but back when this thread started a PC couldn't even play 1080p video.
> 
> 
> Its hard as a newb to figure out where the line is I should start. I was just looking for general advice on that regard. I guess I'll just read the thread backwards ????


 http://www.avsforum.com/t/255432/acoustical-treatments-master-thread/5340#post_17390783 


If you follow this Member's advice you will likely have achieved 80% of all that can be done. BasementBob is knowledgeable and experienced, and is the person responsible for the webpage chocked full of absorption coefficients.


If you want to push your theater to the pinnacle and have disposable income, the pros here can do it. If you are a DIYer and want to educate yourself enough to have a great sounding theater, then stay focused and do more research. Searching out BasementBob's posts are a good place to start.


And by the way, you might want to kill the lateral first reflections if your speakers have bad off axis response. But even the experts don't agree beyond that.


My $.02.


Jeff


----------



## RossoDiamante


I'm starting to think about the acoustic treatment of my theater room build.  I've put a query with some information about the room in my build thread.  I would welcome any advice you can offer over there.  I've read through a lot (I'll be the first to admit not all 9548 posts) and think I understand the basics of what to think about in treating a room.  But I hope to do a little better than basic at the end of the day; without needing to go way overboard!

 

The thread is here:

http://www.avsforum.com/t/1456093/diamante-build-in-dc/30#post_23363708

 

Thanks for your consideration.


----------



## brandon_k_w

I made some mid/high frequency acoustic panels and now I'm left with a 6 quantity of 2" 2'x4' Owens Corning 703 fiberglass. I am thinking of making 4 bass traps with the dimensions of 2'x2' and 6" thick which will be able to use up my remaining fiberglass. Will 6" thick suffice for bass trapping if I stagger then diagonally to the upper/lower wall corners as Ethan Winer does? Perhaps even only make then 4" thick so I can have an extra 2 bass traps? I do not want to buy any more fiberglass, I'm just trying to work with what I have left. I don't have room dimensions to give as these will be used in a future home and I just figure any bass trapping is better than nothing.


By the way, I just bought the fiberglass today and tested them in my room before I started building the frames. The difference these things made was quite remarkable, specifically the imaging. It's quite unfortunate acoustic panels are so elusive, unknown and impossible to demo. My parents were wondering what the hell I was doing when building these things outside.


----------



## RossoDiamante


Pardon the cross-post.  I didn't seem to get much crossover into my build thread and there are some basic fundamentals I don't want to overlook as I get started with this part of my room build out.

 

 

 

 

 

 

I would like to solicit opinions on acoustic treatment of my front wall assembly.  I've enclosed two schematics.  The first one is the top-down view that shows my front wall assembly consisting on a screen wall behind which is a wall to hold the speakers and behind that a couple of feet before getting to the foundation wall.  The "foundation wall" is not the bare concrete but will have 2 layers of 5/8" drywall attached to 2x4" framing (isolated from the ceiling with IB3 clips).

 

The screen wall will host an acoustically transparent screen and the rest of it will be covered with fabric (presumably as acoustically benign as possible).  Thus, except for the framing members and the frame of the screen, this wall is designed to be as acoustically transparent as possible.

 

The speaker wall will just host a few studs to screw my in-wall speakers to.  Each of the speaker bays will have OSB or plywood backers and be filled with fluffy pink stuff to a manufacturer's recommendation of 2.0-2.5 cu. ft. volume.  There will be drywall from side to side and from the top of the speaker cavities to the bottom of the speaker cavities.  The tops and bottoms of the wall will be open between the screen wall and the foundation wall.

 

My understanding is that a good place to start acoustically for reflection control is to put Linacoustic on the "front wall".  And I also believe that there is some consensus that a bunch of loose-fill fiberglass in the "corners" is a good start for bass-trapping.  

 

My initial thoughts would be to fill the majority of the space between the speaker wall and the foundation wall with a bunch of fluffy pink fiberglass.  It would seem that this would offer a good start to bass trapping in the front corners of the room.  My assumption is that the corners of the foundation wall are the "corners" I should be treating and not the intersection between the screen wall the the side foundation walls?  Since the screen wall is supposed to be acoustically transparent, it would seem that I could just ignore it for acoustic treatment purposes.

 

My question now becomes what is the "front wall" that is typically treated with Linacoustic?  I'm actually off to the supplier to pick up some 1" and 2" Linacoustic right now.  I would assume that the Linacoustic would be attached to the drywall of the speaker wall.  Is there a need to put any Linacoustic along the foundation wall - either at the tops or bottoms to cover the areas not protected by the speaker wall drywall and its Linacoustic covering, or the whole foundation walll?

 

Any other thoughts for acoustic treatments would be appreciated.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *brandon_k_w*  /t/255432/acoustical-treatments-master-thread/9540#post_23367160
> 
> 
> I made some mid/high frequency acoustic panels and now I'm left with a 6 quantity of 2" 2'x4' Owens Corning 703 fiberglass. I am thinking of making 4 bass traps with the dimensions of 2'x2' and 6" thick which will be able to use up my remaining fiberglass. Will 6" thick suffice for bass trapping if I stagger then diagonally to the upper/lower wall corners as Ethan Winer does? Perhaps even only make then 4" thick so I can have an extra 2 bass traps? I do not want to buy any more fiberglass, I'm just trying to work with what I have left. I don't have room dimensions to give as these will be used in a future home and I just figure any bass trapping is better than nothing.
> 
> 
> By the way, I just bought the fiberglass today and tested them in my room before I started building the frames. The difference these things made was quite remarkable, specifically the imaging. It's quite unfortunate acoustic panels are so elusive, unknown and impossible to demo. My parents were wondering what the hell I was doing when building these things outside.



It depends really on how low you need to trap. 4" traps in the corners will work well down to 100 Hz in corners. 6" traps would get you close down to 80 Hz in the corners.



> Quote:
> Originally Posted by *RossoDiamante*  /t/255432/acoustical-treatments-master-thread/9540#post_23369859
> 
> 
> 
> I would like to solicit opinions on acoustic treatment of my front wall assembly.  I've enclosed two schematics.  The first one is the top-down view that shows my front wall assembly consisting on a screen wall behind which is a wall to hold the speakers and behind that a couple of feet before getting to the foundation wall.  The "foundation wall" is not the bare concrete but will have 2 layers of 5/8" drywall attached to 2x4" framing (isolated from the ceiling with IB3 clips).
> 
> 
> 
> 
> 
> 
> 
> The screen wall will host an acoustically transparent screen and the rest of it will be covered with fabric (presumably as acoustically benign as possible).  Thus, except for the framing members and the frame of the screen, this wall is designed to be as acoustically transparent as possible.
> 
> 
> 
> 
> 
> 
> 
> The speaker wall will just host a few studs to screw my in-wall speakers to.  Each of the speaker bays will have OSB or plywood backers and be filled with fluffy pink stuff to a manufacturer's recommendation of 2.0-2.5 cu. ft. volume.  There will be drywall from side to side and from the top of the speaker cavities to the bottom of the speaker cavities.  The tops and bottoms of the wall will be open between the screen wall and the foundation wall.
> 
> 
> 
> 
> 
> 
> 
> My understanding is that a good place to start acoustically for reflection control is to put Linacoustic on the "front wall".  And I also believe that there is some consensus that a bunch of loose-fill fiberglass in the "corners" is a good start for bass-trapping.
> 
> 
> 
> 
> 
> 
> 
> My initial thoughts would be to fill the majority of the space between the speaker wall and the foundation wall with a bunch of fluffy pink fiberglass.  It would seem that this would offer a good start to bass trapping in the front corners of the room.  My assumption is that the corners of the foundation wall are the "corners" I should be treating and not the intersection between the screen wall the the side foundation walls?  Since the screen wall is supposed to be acoustically transparent, it would seem that I could just ignore it for acoustic treatment purposes.
> 
> 
> 
> 
> 
> 
> 
> My question now becomes what is the "front wall" that is typically treated with Linacoustic?  I'm actually off to the supplier to pick up some 1" and 2" Linacoustic right now.  I would assume that the Linacoustic would be attached to the drywall of the speaker wall.  Is there a need to put any Linacoustic along the foundation wall - either at the tops or bottoms to cover the areas not protected by the speaker wall drywall and its Linacoustic covering, or the whole foundation walll?
> 
> 
> 
> 
> 
> 
> 
> Any other thoughts for acoustic treatments would be appreciated.



You've definitely understood most of the concepts. The biggest thing to note is the reason for the thin trapping on front wall is mostly just to deaden any reflections coming from your surrounds. So a basic concept to think of is if the reflection is obscured by wood or speaker or something then absorption there wouldn't really make an impact on high frequencies as they'll already be scattered. However, all other areas where direct reflections can come in would be where you would line with Linacoustic. If its possible, I recommend doing 2" everywhere and not using 1" to get absorption lower in frequency. Also, the pink fluffy idea would work well. I think your plan so far looks good.


----------



## Nightlord

Someone mentioned to me that if you 'laminate' insulation in the middle with a layer of alu foil it will improve dampening in the bass range. Is this correct? Any other issues with it?


----------



## LeBon

I'll be using 2 layers of 1 inch Linacoustic with 3 mil. plastic film in between. M understanding is that the purpose of the plastic film is to reduce absorption of higher frequencies.


----------



## Nightlord




> Quote:
> Originally Posted by *LeBon*  /t/255432/acoustical-treatments-master-thread/9540#post_23373149
> 
> 
> I'll be using 2 layers of 1 inch Linacoustic with 3 mil. plastic film in between. M understanding is that the purpose of the plastic film is to reduce absorption of higher frequencies.



ok, that's understandable if used inside the room. Inside the walls there's no need to reduce absorption of anything.


So... is it just a shift, or is bass dampening improved? Anyone?


----------



## RossoDiamante




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9540#post_23370397
> 
> 
> 
> Also, the pink fluffy idea would work well. I think your plan so far looks good.


 

Would the pink fluffy stuff be "configuration" dependent?  In other words in that trapezoidal space between the speaker wall and the foundation wall, given a fixed volume of fluffly pink stuff, would it make a difference if I put a column of insulation floor to ceiling in each of the lateral corners vs. just laying all of that insulation flat on the floor and piling it up as high as it would go given the same volume?  And for sake of argument, assuming I'm using 15" wide insulation, would it make a difference if I made a pile X inches high by putting two "rows" of this 15" insulation butting against each other parallel on the floor vs. taking the same volume of insulation and piling it 2X inches high in one single 15" wide stack against the back foundation wall?


Are my results going to be more dependent upon the actual placement of the insulation or the overall volume?


----------



## LeBon




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9540#post_23373345
> 
> 
> ...Inside the walls there's no need to reduce absorption of anything.



Actually, the idea is to avoid excessive dampening of the higher frequencies in the room, while absorbing low frequencies. It is an "acoustic" treatment, not a "soudproofing" measure.


----------



## Nightlord

Thanks. It improves bass dampening relative to high frequencies but it does not improve dampening per se.


----------



## rabident

I've been going to IMAX a lot. I like the really big screen. Are there any acoustic downsides to having a screen that takes up the whole front wall?


Also, what is the purpose of the stage?


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *rabident*  /t/255432/acoustical-treatments-master-thread/9540#post_23386955
> 
> 
> I've been going to IMAX a lot. I like the really big screen. Are there any acoustic downsides to having a screen that takes up the whole front wall?



If the screen is acoustically transparent, no. If it is not acoustically transparent, then it does make that big acoustically reflective surface even bigger (surround sound bounces off it), and also makes it harder to place L/C/R speakers.


> Quote:
> Originally Posted by *rabident*  /t/255432/acoustical-treatments-master-thread/9540#post_23386955
> 
> 
> Also, what is the purpose of the stage?



Cosmetic


----------



## wse




> Quote:
> Originally Posted by *rabident*  /t/255432/acoustical-treatments-master-thread/9540#post_23386955
> 
> 
> I've been going to IMAX a lot. I like the really big screen. Are there any acoustic downsides to having a screen that takes up the whole front wall?



Yes I love that huge screen am looking to do the same but you need acoustically transparent screen! Elite screen pro 4K


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9540#post_23371053
> 
> 
> Someone mentioned to me that if you 'laminate' insulation in the middle with a layer of alu foil it will improve dampening in the bass range. Is this correct? Any other issues with it?



It doesn't need to be in the 'middle' - it can be on any side. And yes, this gives a slight membrane effect which can enhance low frequency absorption (not by a lot, but it's shown a difference in tests I've seen so...). And I'm not sure if you'd just use plain aluminum foil, the main foil facing that comes on some fiberglass is certainly different than regular foil. You'd want to look for that FRK/FSK facing that is used on the insulation. You can buy it separately.



> Quote:
> Originally Posted by *LeBon*  /t/255432/acoustical-treatments-master-thread/9540#post_23373149
> 
> 
> I'll be using 2 layers of 1 inch Linacoustic with 3 mil. plastic film in between. M understanding is that the purpose of the plastic film is to reduce absorption of higher frequencies.



The high frequencies would already be absorbed by the time it got to the middle of the panel so this wouldn't be the best plan. You'd want the 3 mil between the fabric and the insulation to block off some high frequency absorption. However, it is also worth noting that 3mil is likely much too thin to really block any significant high frequency absorption. 6 mil is borderline, somewhere around 10mil is where I'd look if I wanted high frequencies reflected.



> Quote:
> Originally Posted by *RossoDiamante*  /t/255432/acoustical-treatments-master-thread/9540#post_23373693
> 
> 
> Would the pink fluffy stuff be "configuration" dependent?  In other words in that trapezoidal space between the speaker wall and the foundation wall, given a fixed volume of fluffly pink stuff, would it make a difference if I put a column of insulation floor to ceiling in each of the lateral corners vs. just laying all of that insulation flat on the floor and piling it up as high as it would go given the same volume?  And for sake of argument, assuming I'm using 15" wide insulation, would it make a difference if I made a pile X inches high by putting two "rows" of this 15" insulation butting against each other parallel on the floor vs. taking the same volume of insulation and piling it 2X inches high in one single 15" wide stack against the back foundation wall?
> 
> 
> 
> Are my results going to be more dependent upon the actual placement of the insulation or the overall volume?



You don't want it to be compressed but you aren't describing that. I don't think the orientation of the fibers would have a huge impact - I'm sure there is a difference, but I'm afraid I've never seen testing to confirm one way or the other.


----------



## wse

What do you think of vicoustic http://www.vicoustic.com/vn/Musicbroadcast/default.asp 


Their panels look great!


----------



## Skylinestar

As 90 degree corners in a rectangular room are bad for bass, will there be an advantage to build a room in a shape of an elongated octagon (rectangular with 4 corners cut)?


----------



## Mfusick

I think most fill the corner with the triangle bass traps but I'd be curious to know the answer too.


----------



## pepar




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9540#post_23392858
> 
> 
> As 90 degree corners in a rectangular room are bad for bass, will there be an advantage to build a room in a shape of an elongated octagon (rectangular with 4 corners cut)?





> Quote:
> Originally Posted by *Mfusick*  /t/255432/acoustical-treatments-master-thread/9540#post_23393065
> 
> 
> I think most fill the corner with the triangle bass traps but I'd be curious to know the answer too.










Bad for bass = good for trapping bass. The whole "gang" is there, so why not use that to advantage instead of building a room where the modes are dispersed and impossible to corral? Sorry for mixing metaphors!


----------



## Nightlord

For the front - best use the corners for the subs. In the front you want to kill off as little bass as possible (= very stiff walls), and once the first wavefront has passed by, you want to kill all you can.


I'm not expecting everyone to agree on this.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9540#post_23393526
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Bad for bass = good for trapping bass. The whole "gang" is there, so why not use that to advantage instead of building a room where the modes are dispersed and impossible to corral? Sorry for mixing metaphors!



+1 - by cutting off the corners you're not changing the amount of bass in the room, you're just getting rid of a good area to absorb it.


----------



## pepar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9540#post_23394756
> 
> 
> For the front - best use the corners for the subs. In the front you want to kill off as little bass as possible (= very stiff walls), and once the first wavefront has passed by, you want to kill all you can.
> 
> 
> I'm not expecting everyone to agree on this.



Below the Schroeder frequency, room mode range, I don't thing there is a "front" or for that matter a "rear" to the room. So bass should be trapped anywhere one has the space to place traps. At this time I have SSC-style bass traps only in the front of the room; it sounds stunning. If I ever get a round tuit, I will add some more in the rear.


Jeff


----------



## Nightlord

If you trap all the energy radiating from the subwoofer and backwards into the wall, you loose a huge portion of it's entire power. Given the short distance, that bounce is not problematic, rather beneficial. You want as strong bass as possible for first wave and then as little as possible later. ( 1/8th wavelength @ 80Hz is about half a meter, that's nor a problem to get a subwoofer element within half a meter of both back and side walls ).


(Normal) measurements might not be able to tell the methods apart, but ear will.


----------



## pepar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9540#post_23395204
> 
> 
> If you trap all the energy radiating from the subwoofer and backwards into the wall, you loose a huge portion of it's entire power. Given the short distance, that bounce is not problematic, rather beneficial. You want as strong bass as possible for first wave and then as little as possible later. ( 1/8th wavelength @ 80Hz is about half a meter, that's nor a problem to get a subwoofer element within half a meter of both back and side walls ).
> 
> 
> (Normal) measurements might not be able to tell the methods apart, but ear will.



I have a pair of subs in the front AND all of my traps. (I also have a pair of subs in the rear.) I can assure you that i have great bass. Besides, it's the bass that comes to you directly from the sub that is the "good" bass. The bass you are talking about, the one-bounce stuff, is hitting itself coming off the wall and is already contributing to ringing modes. You're right that any bass that is trapped is lessening the bass energy in the room, but it is lessening the modes/ringing and that's the important part. And you're also right about not everyone will agree with you.


----------



## Nightlord

I don't doubt it.


No, the first bounce that's less than two feet longer is not part of the ringing, it will only support itself. It won't ring or contribute destructively until a much later bounce in the rear. So if you put four-five yards of dampening material in the rear...


----------



## avrignaud

Hey Folks,


I'm in need of some Acoustical Treatment wisdom. Per this thread:

http://www.avsforum.com/t/1466416/the-seattle-craftsman-basement-home-theater-thread/0_100#post_23435032 


I am working on trying to a bit of a home theater/media room in the basement, but on a budget. The pictures in the exact post above are basically what I'm aiming for, as the construction cost should fit within my 40-50k budget. However, as you will see in the pics (included here for reference), there is no sound treatment. The walls are beadboard on the bottom, sheetrock on top.

 
 
 


My question is what would a reasonable, cost-effective acoustic sound treatment look like, both in plan (how/where to apply) and material (what to buy) if I were to build a 7.2 system in this room below:

 


Thanks in advance for any "cutting to the chase" ideas you can offer!


Andre


----------



## GIK Acoustics

Many theaters have acoustic treatments hidden behind wall areas that are covered in fabric, but it seems like you're looking for a more 'aftermarket' solution. There really is a multitude of ways to go about treating the room, especially dependent upon speaker and listener location, but for just a really generic idea of what it might look like with acoustic panels hung around:


----------



## avrignaud




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9570#post_23439549
> 
> 
> Many theaters have acoustic treatments hidden behind wall areas that are covered in fabric, but it seems like you're looking for a more 'aftermarket' solution. There really is a multitude of ways to go about treating the room, especially dependent upon speaker and listener location, but for just a really generic idea of what it might look like with acoustic panels hung around:



Thanks for that... that helps!


I think what I'm struggling with is to understand some of the basics... when I started reading this thread, as well as the Home Theater ebook (which I purchased elsewhere on AVS), I find many opinions but less agreed-up rule of thumb suggestions to address what I'm trying to do. So, maybe it might help if I try to tease out some specific questions?


I agree that I think I'm looking for more of an aftermarket solution — basically panels I can have the contractors mount in the "right" places to get to a better place. Looking at your simple diagram, I guess I'm wondering the following:


1. If I'm looking at a side wall, is ok to leave the bottom part uncovered (ie, remain as beadboard), and then have the upper section of the wall hung with the panels? Or is it important to cover the whole sidewall top to bottom?

2. I understand the front wall (behind the screen) should be both black and sound treated. I assume the entire wall should be covered here?

3. I believe from my reading that carpeting the floor should be fine and I don't need to do anything differently here... true?

4. Am unclear how important it is to treat the ceiling. Also, how important is it to treat the back of the room (from first counter back)?


Finally, once it's clearer where I should put material, how do I select through the different types/thicknesses, and is that different for different areas? Or is there perhaps one "common" material I can use everywhere from GIK or elsewhere?


I hope that makes sense... if there is a different article or thread that addresses this better, I am happy to go and do the reading if someone can point me to it. But as I said, so far, I'm finding lots of opinions and not a clear answer. To be fair, that may well be because I don't currently know enough to ask the right questions... appreciate any tips you can share!


----------



## Nightlord

How wide is the room? If it's narrow ( say 4 meters or less) you need to think about absorbing the reflex, if the room is wider you'll do ok with diffusion.


----------



## Nyal Mellor




> Quote:
> Originally Posted by *avrignaud*  /t/255432/acoustical-treatments-master-thread/9570#post_23440902
> 
> 
> Thanks for that... that helps!
> 
> 
> I think what I'm struggling with is to understand some of the basics... when I started reading this thread, as well as the Home Theater ebook (which I purchased elsewhere on AVS), I find many opinions but less agreed-up rule of thumb suggestions to address what I'm trying to do. So, maybe it might help if I try to tease out some specific questions?
> 
> 
> I agree that I think I'm looking for more of an aftermarket solution — basically panels I can have the contractors mount in the "right" places to get to a better place. Looking at your simple diagram, I guess I'm wondering the following:
> 
> 
> 1. If I'm looking at a side wall, is ok to leave the bottom part uncovered (ie, remain as beadboard), and then have the upper section of the wall hung with the panels? Or is it important to cover the whole sidewall top to bottom?
> 
> 2. I understand the front wall (behind the screen) should be both black and sound treated. I assume the entire wall should be covered here?
> 
> 3. I believe from my reading that carpeting the floor should be fine and I don't need to do anything differently here... true?
> 
> 4. Am unclear how important it is to treat the ceiling. Also, how important is it to treat the back of the room (from first counter back)?
> 
> 
> Finally, once it's clearer where I should put material, how do I select through the different types/thicknesses, and is that different for different areas? Or is there perhaps one "common" material I can use everywhere from GIK or elsewhere?
> 
> 
> I hope that makes sense... if there is a different article or thread that addresses this better, I am happy to go and do the reading if someone can point me to it. But as I said, so far, I'm finding lots of opinions and not a clear answer. To be fair, that may well be because I don't currently know enough to ask the right questions... appreciate any tips you can share!



Depending on how much time you have on your hands you can learn most things you need from reading the forum and studying books.


To really nail the acoustic design though is a lot of work for you by yourself.


An option is to get professional help. You can get free designs through RealTraps, GIK and others (their design time is paid for by you buying their products) or you can employ a consultant at an hourly or fixed price (not as expensive as you probably think) to help with the design. The consultant has the advantage of a wider range of product from many mfgs including DIY.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9570#post_23441410
> 
> 
> Depending on how much time you have on your hands you can learn most things you need from reading the forum and studying books.
> 
> 
> To really nail the acoustic design though is a lot of work for you by yourself.
> 
> 
> An option is to get professional help. You can get free designs through RealTraps, GIK and others (their design time is paid for by you buying their products) or you can employ a consultant at an hourly or fixed price (not as expensive as you probably think) to help with the design. The consultant has the advantage of a wider range of product from many mfgs including DIY.



Unfortunately I've only got two thumbs to point up, but, you've got them!


> Quote:
> Originally Posted by *avrignaud*  /t/255432/acoustical-treatments-master-thread/9570#post_23440902
> 
> 
> Thanks for that... that helps!
> 
> 
> I think what I'm struggling with is to understand some of the basics... when I started reading this thread, as well as the Home Theater ebook (which I purchased elsewhere on AVS), I find many opinions but less agreed-up rule of thumb suggestions to address what I'm trying to do. So, maybe it might help if I try to tease out some specific questions?
> 
> 
> I agree that I think I'm looking for more of an aftermarket solution — basically panels I can have the contractors mount in the "right" places to get to a better place. Looking at your simple diagram, I guess I'm wondering the following:
> 
> 
> 1. If I'm looking at a side wall, is ok to leave the bottom part uncovered (ie, remain as beadboard), and then have the upper section of the wall hung with the panels? Or is it important to cover the whole sidewall top to bottom?
> 
> 2. I understand the front wall (behind the screen) should be both black and sound treated. I assume the entire wall should be covered here?
> 
> 3. I believe from my reading that carpeting the floor should be fine and I don't need to do anything differently here... true?
> 
> 4. Am unclear how important it is to treat the ceiling. Also, how important is it to treat the back of the room (from first counter back)?
> 
> 
> Finally, once it's clearer where I should put material, how do I select through the different types/thicknesses, and is that different for different areas? Or is there perhaps one "common" material I can use everywhere from GIK or elsewhere?
> 
> 
> I hope that makes sense... if there is a different article or thread that addresses this better, I am happy to go and do the reading if someone can point me to it. But as I said, so far, I'm finding lots of opinions and not a clear answer. To be fair, that may well be because I don't currently know enough to ask the right questions... appreciate any tips you can share!



A lot of questions here and a lot of them are personal preferences and some people/companies have specific criteria they try to meet while others have their own. On a forum, it's difficult to give anything but general advice as recommending something for your specific room can be misconstrued and people might try to apply it to a different room, different circumstance, etc..


With that said, there's three main areas of treatment that need to be separated and looked at to answer your questions:

Low frequency resonance (Modes, SBIR, positional problems)

High-gain reflections (first reflections, nearby boundaries to listening position)

Reverberance/room decay (the general mid/high frequency sounds that are left after a direct source is cut off)

There are many ways to deal with all the issues, but a typical solution might be to: treat bass problems in the corners of the room and behind listening position with thicker traps (or tuned/membrane traps if necessary or preferred), treat high gain reflections by either redirecting them (by diffusion or by reflecting them away from listening position) or by absorbing them, and treat overall room decay with panels placed wherever possible on the sidewalls (usually the upper areas) or diffusors which can help keep the room from sounding too dead, but still help by mixing the sound-field so that the ambiance is, well, 'ambiance' instead of 'lots of reflections'

Also important in theater rooms is to treat around the main speakers up front (like treating the front wall) so your surrounds in the back aren't reflecting off the front wall and adding to the sound from up there. You want the surrounds to "surround" you, and you want the sound from the mains to be directly from in front of you without any influence from your rear speakers.


Again, there's a lot of 'stuff' in general that goes into it, and preferences are all over the place. Designers and companies can work with you to determine how to achieve the sound you imagine for the room. If you look at the generic room diagrams you can see how all these problems can come together to be treated by products placed in the right areas, like this shows: http://gikacoustics.com/acoustic-advice/


----------



## avrignaud




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9570#post_23441268
> 
> 
> How wide is the room? If it's narrow ( say 4 meters or less) you need to think about absorbing the reflex, if the room is wider you'll do ok with diffusion.



The room will be about 16 to 17 feet wide (the exact width depends on excavation costs and how close to the edges they can get).


----------



## avrignaud




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9570#post_23441753
> 
> 
> Unfortunately I've only got two thumbs to point up, but, you've got them!
> 
> A lot of questions here and a lot of them are personal preferences and some people/companies have specific criteria they try to meet while others have their own. On a forum, it's difficult to give anything but general advice as recommending something for your specific room can be misconstrued and people might try to apply it to a different room, different circumstance, etc..
> 
> 
> With that said, there's three main areas of treatment that need to be separated and looked at to answer your questions:
> 
> Low frequency resonance (Modes, SBIR, positional problems)
> 
> High-gain reflections (first reflections, nearby boundaries to listening position)
> 
> Reverberance/room decay (the general mid/high frequency sounds that are left after a direct source is cut off)
> 
> There are many ways to deal with all the issues, but a typical solution might be to: treat bass problems in the corners of the room and behind listening position with thicker traps (or tuned/membrane traps if necessary or preferred), treat high gain reflections by either redirecting them (by diffusion or by reflecting them away from listening position) or by absorbing them, and treat overall room decay with panels placed wherever possible on the sidewalls (usually the upper areas) or diffusors which can help keep the room from sounding too dead, but still help by mixing the sound-field so that the ambiance is, well, 'ambiance' instead of 'lots of reflections'
> 
> Also important in theater rooms is to treat around the main speakers up front (like treating the front wall) so your surrounds in the back aren't reflecting off the front wall and adding to the sound from up there. You want the surrounds to "surround" you, and you want the sound from the mains to be directly from in front of you without any influence from your rear speakers.
> 
> 
> Again, there's a lot of 'stuff' in general that goes into it, and preferences are all over the place. Designers and companies can work with you to determine how to achieve the sound you imagine for the room. If you look at the generic room diagrams you can see how all these problems can come together to be treated by products placed in the right areas, like this shows: http://gikacoustics.com/acoustic-advice/



Thanks for the details. I'm definitely beginning to understand the value/need for a designer to come up with a plan here. I'm currently reaching out to Erskine to see if my sort of hybrid room is one that might be of interest to them, and if so, that might be a way to answer some of the sound treatment questions. Though I'm on a tight budget, I've come to the opinion that it probably makes sense to try and get an actual plan for both the contractor to build from, as well as handle the sound design. If that cost doesn't end up working out, I will likely reach out to some of the other suggested solutions here, including GIK (as I appreciate your time and effort thus far!)


Thank you everyone... appreciated!


----------



## wse




> Quote:
> Originally Posted by *avrignaud*  /t/255432/acoustical-treatments-master-thread/9570#post_23438772
> 
> 
> Hey Folks,
> 
> 
> I'm in need of some Acoustical Treatment wisdom. Per this thread:
> 
> http://www.avsforum.com/t/1466416/the-seattle-craftsman-basement-home-theater-thread/0_100#post_23435032
> 
> 
> I am working on trying to a bit of a home theater/media room in the basement, but on a budget. The pictures in the exact post above are basically what I'm aiming for, as the construction cost should fit within my 40-50k budget. However, as you will see in the pics (included here for reference), there is no sound treatment. The walls are beadboard on the bottom, sheetrock on top.
> 
> 
> 
> 
> 
> 
> My question is what would a reasonable, cost-effective acoustic sound treatment look like, both in plan (how/where to apply) and material (what to buy) if I were to build a 7.2 system in this room below:
> 
> 
> 
> 
> Thanks in advance for any "cutting to the chase" ideas you can offer!
> 
> 
> Andre



Very nice room look at Vivoustics very good for WAF


----------



## avrignaud




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9570#post_23442104
> 
> 
> Very nice room look at Vivoustics very good for WAF



I took a look, nice looking stuff! Unfortunately, it appears they're primarily European, and don't have a US sales office. Guessing that might make them a bit more expensive than other options I might find?


This is the site I found for anyone else's further reference: http://www.vicoustic.com/VN/default.asp


----------



## Nightlord




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9570#post_23441753
> 
> 
> With that said, there's three main areas of treatment that need to be separated and looked at to answer your questions:
> 
> Low frequency resonance (Modes, SBIR, positional problems)
> 
> High-gain reflections (first reflections, nearby boundaries to listening position)
> 
> Reverberance/room decay (the general mid/high frequency sounds that are left after a direct source is cut off)
> 
> There are many ways to deal with all the issues, but a typical solution might be to: treat bass problems in the corners of the room and behind listening position with thicker traps (or tuned/membrane traps if necessary or preferred), treat high gain reflections by either redirecting them (by diffusion or by reflecting them away from listening position) or by absorbing them, and treat overall room decay with panels placed wherever possible on the sidewalls (usually the upper areas) or diffusors which can help keep the room from sounding too dead, but still help by mixing the sound-field so that the ambiance is, well, 'ambiance' instead of 'lots of reflections'
> 
> Also important in theater rooms is to treat around the main speakers up front (like treating the front wall) so your surrounds in the back aren't reflecting off the front wall and adding to the sound from up there. You want the surrounds to "surround" you, and you want the sound from the mains to be directly from in front of you without any influence from your rear speakers.



That's one heck of a good summary of home theater acoustics!


----------



## Skylinestar

My front speaker first reflection point is exactly at the spot where my single-seater leather couch is at.









Does the leather couch reflects lots of sound? Detrimental?

Is it worth to dump the couch away? (WAF will disallow that)


----------



## sdurani




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9570#post_23447973
> 
> 
> Does the leather couch reflects lots of sound?


Yes.


> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9570#post_23447973
> 
> 
> Detrimental?


Only if you don't have a similar couch on the opposite wall (will make for a soundstage that is uneven from left to right).


----------



## wse




> Quote:
> Originally Posted by *avrignaud*  /t/255432/acoustical-treatments-master-thread/9570#post_23444613 I took a look, nice looking stuff! Unfortunately, it appears they're primarily European, and don't have a US sales office. Guessing that might make them a bit more expensive than other options I might find?  This is the site I found for anyone else's further reference: http://www.vicoustic.com/VN/default.asp


 

www.vicousticusa.com


----------



## Nyal Mellor

We are a vicoustic dealer and also carry RPG, primacoustic and auralex as well as doing room acoustic analysis and treatment design. Feel free to contact us for more info on their products and how it measures up to what else is out there...free shipping too on reasonable size orders which you won't get ordering direct from the us sales office...


----------



## wse




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9570#post_23451864 We are a vicoustic dealer and also carry RPG, primacoustic and auralex as well as doing room acoustic analysis and treatment design. Feel free to contact us for more info on their products and how it measures up to what else is out there...free shipping too on reasonable size orders which you won't get ordering direct from the us sales office...


RPG is so expensive, free shipping I like that?


----------



## avrignaud




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9570#post_23451087
> 
> www.vicousticusa.com



Thanks for the correct US URL!


----------



## avrignaud

Question for you sound treatment folks. Is it possible to have a sliding door on rollers as an entrance to a home theater that can block sound reasonably well? I ask because I rather like the look and feel of doors similar to this one:

 


However, since this door would be at the bottom of the basement stairs (which connect up to the kitchen/dining room area), I'm afraid noise might be an issue. Not the end of the world to go more traditional, but am curious if there's a reasonable way to mostly sound proof this sort of door considering it's hanging on rollers and doesn't close flush to the wall?


----------



## Brad Horstkotte

Nope (unless you have a very different definition of "reasonably well" than I do)


----------



## avrignaud




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9570#post_23459796
> 
> 
> Nope (unless you have a very different definition of "reasonably well" than I do)



Fair enough... I'm imagining people being able to sleep upstairs at night, if the theater was being played at a pretty significant level (lots of bass). Guess I'll have to look at other options then!


Thanks for the input!


----------



## Dennis Erskine

You want loud and lots of bass plus people upstairs sleeping. The best solution is sleeping pills.


If the ambient noise floor in the bedroom is, say, 33dB and the loudest LF sound is 115dB, you have 79dB* of low frequency energy to kill. That will be a major challenge, an expensive one, and that sliding door isn't going to come close to helping you out.


*The generally accepted standard is not to raise the ambient noise floor in the target space by more than 3dB.


----------



## Glenn Baumann




> Quote:
> Originally Posted by *avrignaud*  /t/255432/acoustical-treatments-master-thread/9570#post_23459859
> 
> 
> Fair enough... I'm imagining people being able to sleep upstairs at night, if the theater was being played at a pretty significant level (lots of bass). Guess I'll have to look at other options then!
> 
> 
> Thanks for the input!




For that to happen you would have to be VERY commited and be willing to spend the coin to build a room within a room decoupled type design!










Being able to play loud at night with people sleeping and lots of bass would even be a tall order for a true "room within a room' type build! "Reasonably loud" with that type design MIGHT be possible though!



... Glenn


----------



## snowkarver

Currently drinking from the fire hose (AVS, Gearslutz, Master Handbook, Toole, GIK, Realtraps, et al) before my next build. This has really opened my ears to new possibilities.


I think I have a basic level of understanding when it comes to absorption and diffusion of higher frequencies, but bass, room modes, and their related wave theory might take a bit more time










That said, I'm planning to build soffits with a light tray for purely cosmetic reasons - but reading about bass traps got me thinking... I'm going to have 16 inches of pink fluffy up there at all the wall-ceiling boundaries and upper tricorners. I've seen several builds with various soffit trap configs - is there any way for me to take advantage of all that insulation for low frequency control? How would I go about that while keeping the rope light tray?


Any other feedback is also very much appreciated. Thanks!


----------



## Nightlord

I'd ponder close to dead-dampening the right wall the same angles as you have the opening to the office to at least try to balance the early side reflections.


----------



## snowkarver




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9570#post_23465187
> 
> 
> I'd ponder close to dead-dampening the right wall the same angles as you have the opening to the office to at least try to balance the early side reflections.



Thanks. My design calls for 2 inch deep fabric frames on all the walls to conceal absorbers, diffusers, and other treatments as needed. How would I dampen that wall to the "same angle" as the opening?


----------



## Nightlord

Draw lines to the opening edges, the flip those over centerline so they now point at right wall instead... Then measure. Can be done with transparent paper if you won't do it on a computer.


----------



## avrignaud




> Quote:
> Originally Posted by *Glenn Baumann*  /t/255432/acoustical-treatments-master-thread/9570#post_23461093
> 
> 
> For that to happen you would have to be VERY commited and be willing to spend the coin to build a room within a room decoupled type design!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Being able to play loud at night with people sleeping and lots of bass would even be a tall order for a true "room within a room' type build! "Reasonably loud" with that type design MIGHT be possible though!
> 
> 
> 
> ... Glenn



All great feedback, with thanks. As it's my place only, I can get away with a bit more noise than I might otherwise. That said, from what Dennis is saying, it doesn't sound prudent to try and go with the sliding door, so I will likely end up with something more traditional and cost effective. This whole project is an exercise in compromises, trying to avoid compromising audio/video quality and landing with something comfortable. I have to keep reminding myself of this so I can be as flexible as possible in meeting the budget goal and actually getting it built!


That said, if I'm lucky and some stocks do well this holiday, I may get a bit of stretch room to play more...


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *snowkarver*  /t/255432/acoustical-treatments-master-thread/9570#post_23465157
> 
> 
> I'm going to have 16 inches of pink fluffy up there at all the wall-ceiling boundaries and upper tricorners. I've seen several builds with various soffit trap configs - is there any way for me to take advantage of all that insulation for low frequency control? How would I go about that while keeping the rope light tray?



Here's a link to the part of my build thread that shows how I approached mine, which has the trapping combined with a light tray - not the only way by any means, but might help to visualize one way of going about it:

http://www.avsforum.com/t/1250265/pimp-my-garage/120#post_19487839 

http://www.avsforum.com/t/1250265/pimp-my-garage/120#post_19525676


----------



## drarunkpgi

I have installed jamo d500 lcr, surrounds and jamo d6 subwoofer

I have attached my room 2d and 3d model

I do have a carpet and perforated false ceiling


http://pl.an/vidbal 




But I do get some kind of echo/reverberation

Any help ? Should I go for acoustic panels / bass traps /carpets on walls/ etc

I need some the best cost effective ( not expensive ) approach to improve acoustics

AVS members , need your advice


----------



## Nightlord




> Quote:
> Originally Posted by *avrignaud*  /t/255432/acoustical-treatments-master-thread/9570#post_23442028
> 
> 
> The room will be about 16 to 17 feet wide (the exact width depends on excavation costs and how close to the edges they can get).



Ok, you'll be ok with just diffusion then. That's a good width.


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9570#post_23441753
> 
> 
> Unfortunately I've only got two thumbs to point up, but, you've got them!
> 
> A lot of questions here and a lot of them are personal preferences and some people/companies have specific criteria they try to meet while others have their own. On a forum, it's difficult to give anything but general advice as recommending something for your specific room can be misconstrued and people might try to apply it to a different room, different circumstance, etc..
> 
> 
> With that said, there's three main areas of treatment that need to be separated and looked at to answer your questions:
> 
> 
> - Low frequency resonance (Modes, SBIR, positional problems)
> 
> - High-gain reflections (first reflections, nearby boundaries to listening position)
> 
> - Reverberation/room decay (the general mid/high frequency sounds that are left after a direct source is cut off)
> 
> 
> There are many ways to deal with all the issues, but a typical solution might be to:
> 
> 
> - treat bass problems in the corners of the room and behind listening position with thicker traps (or tuned/membrane traps if necessary or preferred),
> 
> - treat high gain reflections by either redirecting them (by diffusion or by reflecting them away from listening position) or by absorbing them, and
> 
> - treat overall room decay with panels placed wherever possible on the sidewalls (usually the upper areas) or diffusors which can help keep the room from sounding too dead, but still help by mixing the sound-field so that the ambiance is, well, 'ambiance' instead of 'lots of reflections'
> 
> 
> Also important in theater rooms is to treat around the main speakers up front (like treating the front wall) so your surrounds in the back aren't reflecting off the front wall and adding to the sound from up there. You want the surrounds to "surround" you, and you want the sound from the mains to be directly from in front of you without any influence from your rear speakers.
> 
> 
> Again, there's a lot of 'stuff' in general that goes into it, and preferences are all over the place. Designers and companies can work with you to determine how to achieve the sound you imagine for the room. If you look at the generic room diagrams you can see how all these problems can come together to be treated by products placed in the right areas, like this shows: http://gikacoustics.com/acoustic-advice/



Great explanation, succinct and to the point, thank you! When I have a dedicated room, I will hire you guys!


So putting diffraction in between the front speakers would not be a good idea I take it?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9600#post_23494300
> 
> 
> Great explanation, succinct and to the point, thank you! When I have a dedicated room, I will hire you guys!
> 
> 
> So putting diffraction in between the front speakers would not be a good idea I take it?



It can be and it can't be. It's not that it isn't a good idea, but usually there's a few other places in the rooms that might be more beneficial - you might gain more out of it. But diffusion and scattering can certainly work in areas of late reflections (like the front wall) as it can remove other specular reflections coming from the area. Of course, you still want to keep localization high in the front of the room so I probably wouldn't be very liberal with diffusion applications on the front wall, but they have proved their value to many people in such a spot. Another big problem with it is there usually isn't many areas on the front wall that don't have objects in the way to obscure the sound that would otherwise be diffused before it makes its way to the front wall, so it would obviously do little in these cases.


----------



## Skylinestar

I've read that standard bass traps are for frequencies above 100Hz....below that, we need electronic EQ like Audyssey

This is my waterfall chart (after eq) in a fully concrete living room that is open to the rest of the house. FYI, the 50Hz area is a background hum/noise.

Currently, I only have a 2 x 6" thick traps straddle at the front corners and 2 x 4" thick traps at the sidewalls. I think I need 12 inchers but doubt it'll work below 50Hz.


Will 12" thick bass traps helps to reduce the bass decay below 50Hz?


----------



## pepar

I think you can get some effectiveness under 100Hz, especially with MORE traps. Are you familiar with StudioTips SuperChunk traps? If you are not familiar with the site, explore it. It has been very helpful to me as well as many others.


Jeff


----------



## GIK Acoustics

Thicker corner traps can certainly be effective below 100 Hz - at 50 Hz and below is when it starts to get pretty difficult to adequately trap with limited space. Tuned/resonant/pressure treatments can all be very helpful to address specific modes/problems under 100 Hz with a limited thickness.


----------



## Skylinestar




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9600#post_23496230
> 
> 
> Thicker corner traps can certainly be effective below 100 Hz - at 50 Hz and below is when it starts to get pretty difficult to adequately trap with limited space. Tuned/resonant/pressure treatments can all be very helpful to address specific modes/problems under 100 Hz with a limited thickness.


helmholtz resonator is the way to go then?


or this http://gikacoustics.com/product/gik-acoustics-scopus-tuned-bass-trap-t40/ ?


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9600#post_23497352
> 
> 
> helmholtz resonator is the way to go then?
> 
> 
> or this http://gikacoustics.com/product/gik-acoustics-scopus-tuned-bass-trap-t40/ ?


Yes, Helmholtz resonators, panel resonators, membrane treatments are all types of pressure based treatments that would work well in these cases.


----------



## Skylinestar

Can I place bass traps behind couch or even large cupboard? Will it work?


----------



## wse




> Quote:
> Originally Posted by *GIK Acoustics*  /t/255432/acoustical-treatments-master-thread/9600#post_23494591
> 
> 
> It can be and it can't be. It's not that it isn't a good idea, but usually there's a few other places in the rooms that might be more beneficial - you might gain more out of it. But diffusion and scattering can certainly work in areas of late reflections (like the front wall) as it can remove other specular reflections coming from the area. Of course, you still want to keep localization high in the front of the room so I probably wouldn't be very liberal with diffusion applications on the front wall, but they have proved their value to many people in such a spot. Another big problem with it is there usually isn't many areas on the front wall that don't have objects in the way to obscure the sound that would otherwise be diffused before it makes its way to the front wall, so it would obviously do little in these cases.



So is it better to have absorption on the front wall?


----------



## Nightlord




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9600#post_23504036
> 
> 
> So is it better to have absorption on the front wall?



It's not either or. You should have absoprion on the front wall too.


----------



## wse




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9600#post_23504340
> 
> 
> It's not either or. You should have absoprion on the front wall too.



Ok so how about in between speaker diffusion with absorbption around it !


----------



## Nightlord




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9600#post_23504644
> 
> 
> Ok so how about in between speaker diffusion with absorbption around it !



Think you should sketch out your thinking, that's much too broad brushstrokes.


But I do think you need some harder surfaces too, so you don't overdampen the room, so that might be what you mean.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9600#post_23503923
> 
> 
> Can I place bass traps behind couch or even large cupboard? Will it work?



Yes, but only if they're sufficiently thick! The corners are a great place to trap low frequencies but with a couch in the way its no telling if you'll get much useful action above the transition frequency at all. Modes travel along boundaries, like the floor, and terminate in the corners so usually have no problem moving around objects. So you'll need to make sure that they are thick enough to work for the modes, as thinner treatments that address 200 Hz and up would be quite useless there.


> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9600#post_23504036
> 
> 
> So is it better to have absorption on the front wall?



Definitely depends on the room and the set up!


----------



## brandon_k_w

What do you gents think of my bass trap frame dilemma: building 2'x2' bass traps that are 6" thick and I'm staggering them diagonally in the corners.


I am currently building them as shown in (A) of the diagram, but I've seen people building their bass traps with frame gaps as shown in (B).


Would I notice a significant obstruction of absorption efficiency if I build them as shown in (A)? I do not want to go through the hassle of recutting my boards even more because I'm not a good woodworker and it would seem to be quite time prohibitive.


It is my opinion that since diagonally staggered bass traps are used primarily to absorb bass waves directly entering the front of the trap since those are the waves that reflect from the wall behind it and re-enter the bass trap for that additional absorption, that the frames as shown in (B) are more useful for mounting on a flat wall? Is my assumption correct?


----------



## Nightlord




> Quote:
> Originally Posted by *brandon_k_w*  /t/255432/acoustical-treatments-master-thread/9600#post_23532494
> 
> 
> Would I notice a significant obstruction of absorption efficiency if I build them as shown in (A)?



No. It might even be hard to measure a difference.


----------



## brandon_k_w

Yes! Thank you, saves me a lot of time. I should also mention the plywood I'm using for the frames are 1/2" thick. Hopefully this doesn't change your answer.


----------



## Nightlord

No, but I would not bet my life on that other people might have a different opinion. But given just how little bringing in a bale of insulation into the room does... there's nothing significant about that... then a small edge or not on the frame is definitely not significant. You will also have reflections inside the frame that will make that portion of sound have a marginally longer path through the insulation...


----------



## Nightlord

If you do want to open them up some anyway: Put a hole saw on your drill and make a few large holes in it. No higher carpentry skills required.


----------



## GIK Acoustics




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9600#post_23532523
> 
> 
> No. It might even be hard to measure a difference.



Yeah, I agree with this in most cases. Especially for a corner absorber it should be fine. The main areas where it matters is sidewall panels where a reflection might actually hit off the side of the panel back to listening position when it normally wouldn't have - and you can definitely measure a difference in that case. As with everything in life..always depends on the specifics! But in the above case, you should be fine..


----------



## erkq

Is there a forum here on AVS that deals with general room acoustics? Please suggest it if this is too OT for here.


I've designed home theaters, including my own. But now I've got a client building a house and I'm to install the sound system. These are the largest residential rooms I've ever worked on and when they are complete they will be acoustic nightmares. The living room is 50' long, 20' wide and 24' tall. The kitchen, an "L" at one end, is 20' by 18' and *also* 24' tall! The floors will be *tile*. Acoustic treatment will not pass WAF. The one good thing is the ceiling is pitched so at least the floor and ceiling aren't parallel. But there a too many near square dimensions, too much space, and too many hard surfaces.


What do you guys use to model your theaters? Is there software that'll give an idea of how this room is going to behave?


----------



## Nightlord

Sounds like you're in for a big job. Are the speakers chosen really up to the task of such a big room to begin with?


----------



## Roger Dressler




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9600#post_23535583
> 
> 
> The living room is 50' long, 20' wide and 24' tall.


It would really help to see how the listening area will be arranged within the space. What is the screen size, elevation, and the seating wrt to it?


----------



## erkq




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9600#post_23535953
> 
> 
> Sounds like you're in for a big job. Are the speakers chosen really up to the task of such a big room to begin with?



The speakers haven't been chosen yet. I'm thinking something like Danley subwoofers and some horn loaded mid-bass cabinets like Altec's venerable A-7 with 500Hz horns. SOMETHING that has a prayer of coupling with that large of a space. I'm also thinking that as few speakers as possible would be good to minimize the number of sources for different timings bouncing around in that space. I'm thinking just two! I'm really in over my head with this space. I feel no matter what I do it's gonna sound like a cavern. Remember... tile floors, no sound treatment, no carpet.


> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9600#post_23535996
> 
> 
> It would really help to see how the listening area will be arranged within the space. What is the screen size, elevation, and the seating wrt to it?



Unfortunately it's a living room so the "listening" area is all over. They want background music that can also be "cranked" for dancing. It's that "cranked" part that has me stumped. That's why my first post asked if there was a more appropriate thread. I just thought knowledgeable guys hang out here so I'd try here first.


Thanks guys!


----------



## Nightlord

I'd go for speakers that doesn't radiate much sound towards floor or ceiling then... Linearrays perhaps?


----------



## wse




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9600#post_23536158
> 
> 
> The speakers haven't been chosen yet. I'm thinking something like Danley subwoofers and some horn loaded mid-bass cabinets like Altec's venerable A-7 with 500Hz horns. SOMETHING that has a prayer of coupling with that large of a space. I'm also thinking that as few speakers as possible would be good to minimize the number of sources for different timings bouncing around in that space. I'm thinking just two! I'm really in over my head with this space. I feel no matter what I do it's gonna sound like a cavern. Remember... tile floors, no sound treatment, no carpet.
> 
> Unfortunately it's a living room so the "listening" area is all over. They want background music that can also be "cranked" for dancing. It's that "cranked" part that has me stumped. That's why my first post asked if there was a more appropriate thread. I just thought knowledgeable guys hang out here so I'd try here first. Thanks guys!



You have an echo chamber on your hands, yes line amplified Line array that way they can feel like an arena!


----------



## HopefulFred




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9600#post_23536224
> 
> 
> Linearrays perhaps?


Isn't this the sort of thing that synergy horns are supposed to be good at? (I don't know, that's just what I thought.)


----------



## Brad Horstkotte

How about a pair of 7pi corner horns, and some absorption on the "back" wall (wall hanging tapestries perhaps)?


----------



## Nightlord




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9600#post_23536548
> 
> 
> Isn't this the sort of thing that synergy horns are supposed to be good at? (I don't know, that's just what I thought.)



I have no idea what the directivity pattern of those are. Actually, I don't even know what they are, I have no real interest in horns and I haven't bought a hifi magazine the last decade...


----------



## HopefulFred

For Nightlord:
http://www.danleysoundlabs.com/products/loud-speakers/synergy-horn/


----------



## Nightlord

Thanks. Any googling the net for directivity plots have some nice graps too. Looks like a respectable speaker in that respect at least. Hopefully they do other aspects well too. See they build tapped horn subwoofers too and that's an interesting approach, know of quite a few people who've done that too.


----------



## wse




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9630#post_23537803
> 
> 
> Thanks. Any googling the net for directivity plots have some nice graps too. Looks like a respectable speaker in that respect at least. Hopefully they do other aspects well too. See they build tapped horn subwoofers too and that's an interesting approach, know of quite a few people who've done that too.


 http://www.avantgarde-acoustic.com/horn-loudspeaker-en.html


----------



## Roger Dressler




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9600#post_23536158
> 
> 
> Unfortunately it's a living room so the "listening" area is all over. They want background music that can also be "cranked" for dancing. It's that "cranked" part that has me stumped.


Wait a minute. The stated requirements are:

a) background music

b) crank for dancing


If this is the complete request from the client, that changes matters significantly. Neither of those use cases is overly concerned with the kinds of sound quality attributes we apply to home theaters, such as the ultimate in dialog intelligibility.


I think you could use several Triad inwall units (mains and subs) and meet their goals while keeping things totally out of sight.


If I totally misrepresent their desires, please let us know their complete wish list. If we do not know the problem in detail, we cannot begin to solve it.


----------



## steve71




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9630#post_23537803
> 
> 
> Thanks. Any googling the net for directivity plots have some nice graps too. Looks like a respectable speaker in that respect at least. Hopefully they do other aspects well too. See they build tapped horn subwoofers too and that's an interesting approach, know of quite a few people who've done that too.



Tom Danley actually owns the patent on tapped horns, as he was the one to nail down the design.


Not only does Danley's Synergy horns have great (constant) directivity, they are also the one and only speaker that acts as a true point source. Pretty brilliant design and to top it all off, he's a very nice guy who shares his knowledge on the various DIY speaker building sites (including AVS).


Anyway, enough cheer-leading from me


----------



## wse

The choice for in walls is quite good these days, how does that work with acoustic treatments?


----------



## RossoDiamante




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9630#post_23550414
> 
> 
> The choice for in walls is quite good these days, how does that work with acoustic treatments?



I was just pondering this over the last couple of days as I am getting pretty close to that part of my build.


I am planning on having my LCR speakers behind my screen. My screen manufacturer states that only 1" is required between the speakers and the screen. So my current thoughts are to build a wall that will house my speakers a couple of inches behind the screen wall.


My speaker manufacturer recommend a 2.2 cu. ft. Volume for the speaker enclosures. I was going to build these out of 3/4" MDF. It has been recommended that I somehow isolate these enclosures from the wall. Not exactly clear why. But my plan was to usea couple of IB3 clips to the wall framing. I would then finish the wall with 1/2" drywall and 2" Linacoustic. The speaker enclosure would then be mounted (on IB3 clips) to the wall so that the face of the speakers lie in the same plane as the face of the Linacoustic.


This wall would extended from the stage below to the bulkhead above. There is space behind this wall for insulation to act as a bass trap as well as space for my 2 subwoofers. But in order for this space to act effectively as a bass trap, my assumption is that it needs to be open to the main room somehow. So my plan was to leave 1-2 feet at the top and/or bottom of the wall for the waves to get back to the bass trap area. This will also let my subs vent their fury into the room.


Would this be the right way to build this type of speaker wall?


----------



## LowellG

I have a very limited front stage for bass traps.  


What if I took some 703 and glued 4, 2" pieces together. Then, all I can fit is about 12" wide. So I would have a 10"x12"x48" column for a bass trap. I would wrap it of course, but would that work? All the corner bass traps are always triangles, but is a square OK?


----------



## bass addict

OK, guys I could use a little direction on taming the bass at the back of my room. Aesthetics are important, so it's a balancing act between form and function. I have a tougher layout as it is narrow and the rear seats are about 2' from the back wall. Bass at the main row of seats has a slight hole around 30-40hz. I can't really push that any further as the back row happens to have a spike around the same area. When watching FOTP, the back row is getting hammered while the front row is lacking a bit. I have plans down the road to add another pair of subs at the back of the room to help with the FR, but don't think that will totally alleviate the problem.


Here is a pic of the back of the room. I have a doorway on one side, so I am not able to place corner traps in both sides. Would hanging 4" thick frames filled with pink fluffy help out a bit here? The front behind the screen is treated with corner traps and wall treatments consisting of linacoustic and OC703 (1 and 2").


Also, due to the narrow width I used 1" thick 703 on the sidewall at the first reflection points. I'm thinking about adding some to the ceiling. Is 1" a waste of time for first reflection points? Should I go with 2" on the ceiling? I could also use some help with the slap echo. The room is still pretty live.


----------



## HopefulFred




> Quote:
> Originally Posted by *LowellG*  /t/255432/acoustical-treatments-master-thread/9630#post_23557655
> 
> 
> All the corner bass traps are always triangles, but is a square OK?


Changing the shape isn't going to change a whole lot, though there are trade-offs going on in terms of total sabines of absorption and effectiveness at particular frequencies (I think that's the right way to say that). Do what you can, but it's hard to know without knowing what problems you need to address.


----------



## HopefulFred




> Quote:
> Originally Posted by *bass addict*  /t/255432/acoustical-treatments-master-thread/9630#post_23559547
> 
> 
> Bass at the main row of seats has a slight hole around 30-40hz. I can't really push that any further as the back row happens to have a spike around the same area. ...Would hanging 4" thick frames filled with pink fluffy help out a bit here? The front behind the screen is treated with corner traps and wall treatments consisting of linacoustic and OC703 (1 and 2").
> 
> 
> Also, due to the narrow width I used 1" thick 703 on the sidewall at the first reflection points. I'm thinking about adding some to the ceiling. Is 1" a waste of time for first reflection points? Should I go with 2" on the ceiling? I could also use some help with the slap echo. The room is still pretty live.


If your room were mine, I'd try adding the absorption (basically as much as I could fit) behind the screen. Primary modes are really tough to control with porous absorption - so ultimately the solution may be more tailored with the extra subs you're talking about and maybe some tuned traps of some sort. (I'm assuming the 30-40Hz problem is the primary length mode of the room - I think that's a safe bet) I wouldn't expect a whole lot in that frequency range with anything less than 8 inches or so, but my expectations could be off.


Is it possible to swap the 1' treatments to the ceiling and use 2 at first reflection points? I know you have a width problem, but I would say the 1" is better for less frequency-critical applications, like over head. I'm not in a position to say whether 1" is a waste of time at first reflections, but you run the risk of hurting the frequency response without changing the ISD and improving intelligibility, depending on a variety of factors including directivity and toe-in.


That's just one guy's opinion.


----------



## wse


Has any one used this Godfrey Hirst, Nature Underfoot & Bigfoot instead of Owen Corning, I am just try to go Formaldehyde free?

 

*Thick, cushy, 100% virgin New Zealand wool carpet pad - 24 oz and 36 oz*


Godfrey Hirst's thick, luxurious carpet cushions surpass all expectations. Unlike carpet padding made from petroleum-based urethanes, synthetic latex or questionable post consumer content, these unique cushions are made from 100% pure virgin wool. They are all-natural products, not laced with toxic additives.

Nature Underfoot comes in two thicknesses: The regular Underfoot is the lighter and thinner option weighing 24 oz a square yard and is 1/4" thick. The Bigfoot is the heavier and thicker option weighing 36 oz a square yard and is 1/2" thick. 

Features & benefits
*Renewable* — sheep can be shorn every nine to 12 months
*Natural, biodegradable* — made from sun, rain and grass; returns to soil after decomposition
*Odor-free* — non-offensive to installer and occupants
*Naturally flame-retardant *— difficult to ignite due to higher ignition temperature; wool contributes less to smoke or toxic gas formation, compared to synthetics.
*Adds longevity to carpet* — reduces pile-height loss and pile crushing; cushion can help keep a carpet 'new' looking and therefore increase its usable life span
*Improves carpet acoustical properties* — carpeted environments are quiet because the pile surface absorbs surface noise; carpet installed with a carpet cushion makes the room even more quiet.
*Improves thermal propeties* — adds from .75 to 2.0 R-value
*Safe* — for everyone, including the chemically sensitive;  learn how to test a non-toxic product for tolerance


----------



## bass addict




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9630#post_23559819
> 
> 
> If your room were mine, I'd try adding the absorption (basically as much as I could fit) behind the screen.



That's been done. There isn't much space left back there for anything other than speakers.










> Quote:
> Primary modes are really tough to control with porous absorption - so ultimately the solution may be more tailored with the extra subs you're talking about and maybe some tuned traps of some sort. (I'm assuming the 30-40Hz problem is the primary length mode of the room - I think that's a safe bet) I wouldn't expect a whole lot in that frequency range with anything less than 8 inches or so, but my expectations could be off.



8" is probably more than I can do in the back. I couldn't do more than about 4" without it looking like a recording studio.


> Quote:
> Is it possible to swap the 1' treatments to the ceiling and use 2 at first reflection points? I know you have a width problem, but I would say the 1" is better for less frequency-critical applications, like over head. I'm not in a position to say whether 1" is a waste of time at first reflections, but you run the risk of hurting the frequency response without changing the ISD and improving intelligibility, depending on a variety of factors including directivity and toe-in.
> 
> 
> That's just one guy's opinion.



Unfortunately it's not. The columns were custom built for 1" acoustic materials. I've got a lot of hours involved in ripping, routing, sanding, and painting; and I'm not about to start over with that.


I really would like to get away with 1" on the ceiling as well, but 2" wouldn't kill me there as I'll be building frames from scratch there. I just want it to blend in with the rest of the decor.


----------



## HopefulFred

I would have a hard time arguing (to myself) that the extra inch was going to matter in your scenario. I'm sure others have different perspectives, but it might be hard to say without a comprehensive set of measurements. I suspect that 1" should be adequate for most slap echo problems.


----------



## NicksHitachi




> Quote:
> Originally Posted by *bass addict*  /t/255432/acoustical-treatments-master-thread/9630#post_23559547
> 
> 
> OK, guys I could use a little direction on taming the bass at the back of my room. Aesthetics are important, so it's a balancing act between form and function. I have a tougher layout as it is narrow and the rear seats are about 2' from the back wall. Bass at the main row of seats has a slight hole around 30-40hz. I can't really push that any further as the back row happens to have a spike around the same area. When watching FOTP, the back row is getting hammered while the front row is lacking a bit. I have plans down the road to add another pair of subs at the back of the room to help with the FR, but don't think that will totally alleviate the problem.
> 
> 
> Here is a pic of the back of the room. I have a doorway on one side, so I am not able to place corner traps in both sides. Would hanging 4" thick frames filled with pink fluffy help out a bit here? The front behind the screen is treated with corner traps and wall treatments consisting of linacoustic and OC703 (1 and 2").
> 
> 
> Also, due to the narrow width I used 1" thick 703 on the sidewall at the first reflection points. I'm thinking about adding some to the ceiling. Is 1" a waste of time for first reflection points? Should I go with 2" on the ceiling? I could also use some help with the slap echo. The room is still pretty live.



Its gonna be hard to address that region effectively without a truck load of porous absorption. An inch or two here or there is not going to touch that region at all.


AFA slap echo or any other non modal energy IMO 2" is better than 1" but not by much IMHO.


For tuned surgical treatment of trouble frequencies you might do better with tuned panel bass traps and/or Helm Holtz. However for a 30-40Hz gap youd need a couple to several Helm Holtz resonators tuned across that FR I would think.


Sub placement would be your best tool, followed by panel bass traps, followed by HH resonators IMO.


What are the dimensions of your room. What are the seating distances? Is that 30-40Hz hole across the entire row or just the center seat?


----------



## janick

Could I please get your opinion on my room. Treating the windows on the right is not an option, wife wants nothing covering them. I'd like to know if acoustic treament would be worth the expense and effort on the other walls. Becuase I can't cover the windows with a thick curtains, my options may not be worth the effort. Thanks in advance for your advice.

 ;


----------



## sdurani




> Quote:
> Originally Posted by *bass addict*  /t/255432/acoustical-treatments-master-thread/9630#post_23559547
> 
> 
> Bass at the main row of seats has a slight hole around 30-40hz. I can't really push that any further as the back row happens to have a spike around the same area.


Might be a length mode. Is your room around 16-18 feet long? Also, are you willing to move your subwoofers to minimize the hole in the bass response?


> Quote:
> Originally Posted by *bass addict*  /t/255432/acoustical-treatments-master-thread/9630#post_23559547
> 
> 
> Is 1" a waste of time for first reflection points?


Like turning down the treble knob.


----------



## HopefulFred




> Quote:
> Originally Posted by *janick*  /t/255432/acoustical-treatments-master-thread/9630#post_23562612
> 
> 
> Could I please get your opinion on my room.


There are real improvements to be made in the frequency response of your mains by absorbing in the area of wall directly behind them. Frequency response plots will show dips in the response due to SBIR in the range of 200Hz or so.


----------



## Nightlord

Why can't you get somerhing thick that's not permanent for those occassions when the sound is the more important? Heavy sliding curtains... Will improve the picture too by making room darker...


----------



## janick

Honestly, decor is more important. My goal is to do something to help improve the sound, mostly movies and not music, without curtains. I guess i'm asking, and hopefulfred answered, is can i improve the sound with treatments on the back and left walls. Or i'm i wasting my time doing treaments to those walls cause the windows will negate any benefit


----------



## Jeff in Canada

I want to use the Fabricmate system to hold my GOM Fabric on my columns. To have access to my speakers I was going to leave a few screws available to take some of it apart. If I put in the Fabricmate system inset to my wood columns, am I able to pull / push the fabric out of the track so that I can remove it to get access and then reinstall it? Does it allow for that?


----------



## sojodave

I have some questions regarding acoustic panels. I have a big room (22 x 32) with an echo as big as the grand canyon. I finally got a hold of OC 703 locally and I'm ready to make 12 - 2' x 4' 2" thick acoustic panels. I bought Jet Set Brown fabric at Joann's and I also bought furring strips at HD. Here are my questions.

I'm guestimating that the panels will be about 15" apart, is there a "rule of thumb" of how far the panels should be from each other?
I'm thinking that the panels would be about a foot from the ceiling, how high should I install the panels?
I bought some pads to give the panels space behind them, does it make a difference how far the panels are from the wall?
Should I put fabric on the back of the panels or use spray glue on the sides of the insulation?


----------



## steve71




> Quote:
> Originally Posted by *sojodave*  /t/255432/acoustical-treatments-master-thread/9630#post_23566037
> 
> 
> I have some questions regarding acoustic panels. I have a big room (22 x 32) with an echo as big as the grand canyon. I finally got a hold of OC 703 locally and I'm ready to make 12 - 2' x 4' 2" thick acoustic panels. I bought Jet Set Brown fabric at Joann's and I also bought furring strips at HD. Here are my questions.
> 
> I'm guestimating that the panels will be about 15" apart, is there a "rule of thumb" of how far the panels should be from each other?
> I'm thinking that the panels would be about a foot from the ceiling, how high should I install the panels?
> I bought some pads to give the panels space behind them, does it make a difference how far the panels are from the wall?
> Should I put fabric on the back of the panels or use spray glue on the sides of the insulation?



1) You want to catch the first reflection, so use the mirror technique to locate the correct spots.

2) IIRC the top of the panels should be a bit above ear height when sitting down

3) OC703 should be spaced 1" out from the wall.


----------



## janick

I plan on purchasing the OC 703 with burlap and Super Multipurpose Adhesive Aerosol. Forgive my ignorance but I've been unable to find a thread that explains installation options. i.e options with wood frame or not, how most hang on walls, best way to glue burlap to minimize my learning curve. Is there a thread out there for this?


----------



## landshark1




> Quote:
> Originally Posted by *bass addict*  /t/255432/acoustical-treatments-master-thread/9630#post_23559547
> 
> 
> OK, guys I could use a little direction on taming the bass at the back of my room. Aesthetics are important, so it's a balancing act between form and function. I have a tougher layout as it is narrow and the rear seats are about 2' from the back wall. Bass at the main row of seats has a slight hole around 30-40hz. I can't really push that any further as the back row happens to have a spike around the same area. When watching FOTP, the back row is getting hammered while the front row is lacking a bit. I have plans down the road to add another pair of subs at the back of the room to help with the FR, but don't think that will totally alleviate the problem.
> 
> 
> Here is a pic of the back of the room. I have a doorway on one side, so I am not able to place corner traps in both sides. Would hanging 4" thick frames filled with pink fluffy help out a bit here? The front behind the screen is treated with corner traps and wall treatments consisting of linacoustic and OC703 (1 and 2").
> 
> 
> Also, due to the narrow width I used 1" thick 703 on the sidewall at the first reflection points. I'm thinking about adding some to the ceiling. Is 1" a waste of time for first reflection points? Should I go with 2" on the ceiling? I could also use some help with the slap echo. The room is still pretty live.


From what I'm told from Bryan Pape, as I also have a 40hz null & different bass performance between 2 rows problem too, to fix such a low frequency, you'll need at least 6" thick of OC703, 8" would be idea. As for the slap echo, I could tell you 1" thick of linacoustic is good enough.


----------



## sdurani




> Quote:
> Originally Posted by *landshark1*  /t/255432/acoustical-treatments-master-thread/9630#post_23568846
> 
> 
> I also have a 40hz null...


That could be caused by a resonance from a 14-15 foot dimension in your room. IF your room length or width fits that number, could you try temporarily moving your sub to the midpoint of that dimension and re-measuring to see if it eliminated the 40Hz null?


----------



## landshark1




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9630#post_23569020
> 
> 
> That could be caused by a resonance from a 14-15 foot dimension in your room. IF your room length or width fits that number, could you try temporarily moving your sub to the midpoint of that dimension and re-measuring to see if it eliminated the 40Hz null?


Yes, my room dimension is 15'x20' and the 1st row is 7' from the back wall. So I was suggested to move the 1st row 6"-12" further away from the back wall and a stack of OC703 at least 6-8" thick. I just bought the OmniMic and will do some measurement. However, I only have 3 options for sub, either side of the center channel up front, or rear right corner at the back. I'm currently have the sub at the back corner location and moved the seats 6" further away from the back wall, it helps a bit. But ultimately, I would like to be able to fit 2 sub up front even tho 1 up front, 1 at the back might be the best bet for smoother FR through out the 2 row seats.


----------



## sdurani




> Quote:
> Originally Posted by *landshark1*  /t/255432/acoustical-treatments-master-thread/9630#post_23569075
> 
> 
> I just bought the OmniMic and will do some measurement.


What did you use to find out you have a 40Hz null?


> Quote:
> Originally Posted by *landshark1*  /t/255432/acoustical-treatments-master-thread/9630#post_23569075
> 
> 
> I only have 3 options for sub, either side of the center channel up front, or rear right corner at the back.


Can you place the sub under the centre speaker or temporarily in front of the centre speaker for one measurement?


----------



## landshark1




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9630#post_23569330
> 
> 
> What did you use to find out you have a 40Hz null?
> 
> Can you place the sub under the centre speaker or temporarily in front of the centre speaker for one measurement?


I borrowed Big's OmniMic for some quick measurement when we finished the room.


----------



## janick

I plan on purchasing the OC 703 with burlap and Super Multipurpose Adhesive Aerosol. Forgive my ignorance but I've been unable to find a thread that explains installation options. i.e options with wood frame or not, how most hang on walls, best way to glue burlap to minimize my learning curve. Is there a thread out there for this?


----------



## LowellG

Google this or anything else. There are multiple videos and articles for building acoustic panels. There is way more than one option choose the one that works best.

http://www.youtube.com/results?search_query=acoustic+panel+703&oq=acoustic+panel+703&gs_l=youtube.3...13882.18202.0.18533.20.15.1.4.4.0.92.1070.15.15.0...0.0...1ac.1.11.youtube.x094vztvlgM


----------



## sojodave




> Quote:
> Originally Posted by *janick*  /t/255432/acoustical-treatments-master-thread/9630#post_23572328
> 
> 
> I plan on purchasing the OC 703 with burlap and Super Multipurpose Adhesive Aerosol. Forgive my ignorance but I've been unable to find a thread that explains installation options. i.e options with wood frame or not, how most hang on walls, best way to glue burlap to minimize my learning curve. Is there a thread out there for this?


 http://www.aaronbrownsound.com/571/ 


I followed these instructions and built four out of my twelve panels this weekend. I used the Jet Set material from Joann's. I bought the OC 703, but I almost went with Roxul 60. I thought about using movie posters through spoonflower.com. I can't imagine how difficult it would be to get the movie posters straight and true on the wooden frames. I'm glad I didn't go the movie poster route. They are easy to build, but there are a lot of details and they do take a while.


----------



## bass addict




> Quote:
> Originally Posted by *landshark1*  /t/255432/acoustical-treatments-master-thread/9630#post_23568846
> 
> 
> From what I'm told from Bryan Pape, as I also have a 40hz null & different bass performance between 2 rows problem too, to fix such a low frequency, you'll need at least 6" thick of OC703, 8" would be idea. As for the slap echo, I could tell you 1" thick of linacoustic is good enough.



Well I guess I don't have a problem building 3 frames for the back of the room that are 6" thick. I don't think I could manage to get much thicker than that and still be able to open the door enough.


Would pink fluffy work better than OC? I'm fine either way, but pink fluffy is obviously more readily available.


It's good to know you've had success with 1" as I'd like to stick with that for the ceiling. I was utilizing 1" linacoustic 4' up around the entire room in my original build, but when you're working with a theater that is only 10' 8" wide, losing 2" of width is a big deal. Hence I got rid of it. Everything is about compromises.


----------



## sojodave

I had to show off my new acoustic panels. I used felt stacked 1" deep to space them from the walls. I used the Jet Set Pottery Soil (Brown) material from Joann's and wrapped OC 703 with wood panels. I put a backing on mine with Musin Linen because Mrs. Sojodave was worried about having exposed insulation in the room. I'm hanging twelve in my room that is 22' x 32'. I was worried there would be no difference in sound, but I can already tell that the room has less echo.


----------



## sojodave

Does anyone know how to reduce cross talk noise through your vents? Our home theater room is in our basement and you can clearly here movie dialog in the bedrooms upstairs. I've done a lot of research on this and I've seen a few options, but I haven't heard from anyone who have had success cutting down on cross talk through the vents. Does anyone have any solutions?


----------



## sojodave

I finished hanging my twelve acoustic panels. I ran Audyssey on my Denon 1913 and I was surprised at the differences. Before the acoustic panels, Audyssey set my subs at -2 and my fronts to 0 and my rears to +1.5. After the acoustic panels, it set my subs to -7, my fronts to +1 and my rears to +3.5. I put on my favorite demo blu rays and I couldn't believe how wide the sound stage sounded. Details in the fronts and sides were very noticeable. Dialogue from the center channel was clearer and all the speakers seem to disappear in the room. Bass was tight and cleaner on music and on movies. Of course, Mrs. Naylor couldn't tell a difference...










I must admit, I kinda miss the BA BOOM bass I had before. I know that bass is supposed to sound tight and clean, but I have been used to an overly loud bass sound that stood out during lfe sections of movies. My future plans include hanging some bass traps on the ceiling and covering the back wall with linacoustic.


I used the mirror trick to make sure first reflections were covered with acoustic panels on the walls. Is there a way to use the mirror trick on the ceiling?


----------



## sdurani




> Quote:
> Originally Posted by *sojodave*  /t/255432/acoustical-treatments-master-thread/9660#post_23588706
> 
> 
> I kinda miss the BA BOOM bass I had before.


Then turn up the bass, either using the Bass control or raising the subwoofer level. Now that you've improved the quality of the bass, no reason why you can't increase the quantity of the bass till it suits your taste. Experiment in small increments.


----------



## wse




> Quote:
> Originally Posted by *sojodave*  /t/255432/acoustical-treatments-master-thread/9660#post_23581581
> 
> 
> I had to show off my new acoustic panels. I used felt stacked 1" deep to space them from the walls. I used the Jet Set Pottery Soil (Brown) material from Joann's and wrapped OC 703 with wood panels. I put a backing on mine with Musin Linen because Mrs. Sojodave was worried about having exposed insulation in the room. I'm hanging twelve in my room that is 22' x 32'. I was worried there would be no difference in sound, but I can already tell that the room has less echo.



Nice work!


Questions:


1. Why space them off the wall by 1"?


2. Could I use OC 705 rather than 703, is that better worst?


3. I am planning to do 24" x 24" x 4" panels how many do I need the front wall is 9 x 12.


4. I also plan on using these to provide some diffusion

http://www.vicoustic.com/VN/Homecinema/produtoInfo.asp?Id=106 

Multifuser Wood 64


Made from solid wood, the new diffuser is perfect for use in venues such as concert halls, hi-fi rooms and recording studios, where effective diffusion is often required, without too much absorption occurring at the same time. With its striking angled surface, the two-dimensional diffuser is based on a QRD sequence combined with changing reflection techniques (a result of the angled surface).


The panel itself is made in two parts. Each part can be rotated in different directions so that a uniform, omni-directional scattering of sound is achieved, with particularly effective diffusion of mid and low frequencies. Multifuser Wood 64 works between 310Hz and 8kHz.As well as its acoustic efficiency, the panel’s attractive appearance makes it suitable for use in a range of settings. Available in Light Brown, Black and White finishes.


Product Technical Information

Material: Solid Wood


----------



## LowellG

Is 703 stiff enough to just wrap in fabric and mount?


----------



## LeBon

Yes it is. I did that in my last theatre where I wanted an absorber. Use 3M Super 77 spray adhesive to hold the fabric onto the OC703. Hang it with impaling clips ( http://www.acousticalsolutions.com/impalling-clips ) on the wall.


----------



## giomania




> Quote:
> Originally Posted by *sojodave*  /t/255432/acoustical-treatments-master-thread/9660#post_23585471
> 
> 
> Does anyone know how to reduce cross talk noise through your vents? Our home theater room is in our basement and you can clearly here movie dialog in the bedrooms upstairs. I've done a lot of research on this and I've seen a few options, but I haven't heard from anyone who have had success cutting down on cross talk through the vents. Does anyone have any solutions?



I have the same problem, but it is very muted, even at -10 dB volume levels. I have a three-level house. I have a large return vent box in the room, but the HVAC guy lined it with Linacoustic. The supply vents in the room have nothing in them.


This is an un-educated guess, maybe you could afix some linacoustic in there? You have to be careful to mess with the air flow, but if you have extra capacity, you may have some leeway.


I think if incorporated in the HVAC design phase, incorporating several 90-degree turns in the ducts, (with the turns lined with Linacoustic perhaps?), or something like this in line before the vent are helpful.


Mark


----------



## LowellG

Do corner bass traps need to be triangles? I was thinking af making a 1 foot by 1 foot column. I have space issues and I figure that is better than nothing.


----------



## Brad Horstkotte

No, they don't have to be triangles, it just works out as a fairly efficient use of material - if you don't have the width available to make wide triangles, rectangular works too.


----------



## Nightlord

1/4th of an octagon works too


----------



## sojodave




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9660#post_23590755
> 
> 
> Nice work!
> 
> 
> Questions:
> 
> 
> 1. Why space them off the wall by 1"?
> 
> 
> 2. Could I use OC 705 rather than 703, is that better worst?
> 
> 
> 3. I am planning to do 24" x 24" x 4" panels how many do I need the front wall is 9 x 12.
> 
> 
> 4. I also plan on using these to provide some diffusion


1. You want them at least 1" off the wall so you have a soft service for the sound to hit. You don't want a hard surface directly behind the panels.


2. Yes, you could use 705, but 4" panels may not be aesthetically pleasing, especially if your married.


3. Look up on Youtube. "acoustic mirror trick". There are many videos that will show you how to find your first reflective points. That is where you need your panels.


----------



## Brad Horstkotte

>>You want them at least 1" off the wall so you have a soft service for the sound to hit. You don't want a hard surface directly behind the panels


Nonsense


----------



## erkq




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9660#post_23599534
> 
> 
> 
> Nonsense



You are usually a little more elucidating...


----------



## Brad Horstkotte

Haha sorry, feeling cranky I guess. The space between insulation and the wall has nothing to do with keeping the insulation away from a hard surface - rather it is a way to get most of the benefit of thicker insulation, with less cost. 2" insulation on wall > 1" insulation + 1" air gap > 1" insulation on wall.


----------



## erkq




> Quote:
> Originally Posted by *Brad Horstkotte*  /t/255432/acoustical-treatments-master-thread/9660#post_23599886
> 
> 
> Haha sorry, feeling cranky I guess. The space between insulation and the wall has nothing to do with keeping the insulation away from a hard surface - rather it is a way to get most of the benefit of thicker insulation, with less cost. 2" insulation on wall > 1" insulation + 1" air gap > 1" insulation on wall.



Haha... *There* you are!


----------



## nickbuol

OK acoustical panel masters.


I've got the sizes, placements, coverings, insulation (OC703) all figured out and ready to go. I can not do 4" panels on my side walls or even 2" panels with 2" gap, so I will just have to deal with 2" on wall.


Anyway, I thought that I was being pretty smart with getting a 1/2" x 48" x 96" sheet of MDF and then going to cut exactly 2" strips to use for the frames for the panels.


Easy enough to do since I have the tools to do it, and I know that I might need some aditional bracing etc, but that isn't my question...

_*How could I attach the acoustical fabric to the back of the frame?*_

*I have the 1/2" *edge* of MDF to work with.*


I've heard of all sorts of methods: Hot glue, CA glue with activator (not sure that I like how fast that becomes permanent), regular manual staple gun, or staple gun/air compressor combo.


I have access to all of those but the CA glue, but if the recomendation comes back to use something besides MDF, then I need to NOT experiment and return the sheet and get something else.


I have been searching the internet and this site for HOURS and not finding anything. I've seen people wrapping MDF and stappling to the face of it for headboards. I've seen people taking MDF and plywood and making a "sandwich" to make the back plywood, but that was for people making 1" thick panels with a wide frame. Nothing on attaching to the edge of MDF.


Please advise or point me in the right direction. I know that for some of you acoustical experts, you will want to dive into the acoustical piece of it, but I've been researching, measuring, planning for about a month now and I feel like I have the best for what I can do with my budget/room/spouse limitations. I just need help with the construction piece.


Thanks all.


----------



## LeBon

Get an air stapler (Porter Cable US58). That should be all you need. Some 3M Super 77 spray adhesive may be useful for holding down any loose ends.


----------



## Brad Horstkotte

Could you (pneumatic) staple to the inside face (wrap over outside "face", around back "edge", and staple to inside "face"? Or try shooting some test staples to a 1/2" edge and see if there are any issues with splitting/holding - maybe works fine, never tried it.


----------



## nickbuol

LeBon, yup. I already have an air stapler. Used it when I built my 138" frame and had to attach my Seymour XD screen material. It made it so easy. Oh, I also have plenty of Super 77 spray which I used for another HT project recently.


Brad, I see what you are saying. That might work. Instead of putting the backing fabric on first, putting the insulation in, and then wrapping the front, it would be the reverse. Put the colored fabric on the front, then fill it, and then put the backing on.



My only problem will be that the fabric I am going to use comes in a 42" width. Meaning that the longer edge (36") plus the .5" for each end of the frame, plus 2" for each of the frame heights, plus the .5" wrap around the back, puts it at exactly 42" needed without being able to wrap it inside. I have a 1 yard sample of the material, and it has some stretch. Just not sure if I can get enough extra.


Like I mention, I would just try to run a staple into the end of my sheet of MDF, but if it doesn't work and damages the sheet, I won't be able to return the sheet. I have some spare 3/4" MDF that would be similar I guess.


----------



## sojodave

 http://www.harborfreight.com/3-in-1-stapler-brad-pin-nailer-93749.html 


I used this electric stapler and I made twelve panels and didn't have it jam once. It drove 1/2 inch and 3/8 inch staples and was a life saver. I also used cloth duct tape to pull the fabric tight before I used the staples. Duct tape has got to be the greatest invention ever.


----------



## nickbuol




> Quote:
> Originally Posted by *sojodave*  /t/255432/acoustical-treatments-master-thread/9660#post_23606397
> 
> http://www.harborfreight.com/3-in-1-stapler-brad-pin-nailer-93749.html
> 
> 
> I used this electric stapler and I made twelve panels and didn't have it jam once. It drove 1/2 inch and 3/8 inch staples and was a life saver. I also used cloth duct tape to pull the fabric tight before I used the staples. Duct tape has got to be the greatest invention ever.



I have a decent $50 electric stapler in addition to my air stapler. Were you using MDF for the frames?

Great idea on the cloth duct tape.


----------



## nickbuol

Man do I wish that I lived in Michigan....


I know that he won't see my response, but still.


----------



## erkq




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9660#post_23608216
> 
> 
> Man do I wish that I lived in Michigan....
> 
> ...


*Really??*


----------



## nickbuol




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/9660#post_23609399
> 
> *Really??*



Yes. Really. I live in Iowa, so it isn't like it is much colder in winter (depending on where you live). Plus I am a die hard Michigan Wolverines fan. I hate the Iowa "Duckeyes", and could take or leave the Iowa State "Breezy Winds."


Plus I could go visit the Lake Michigan sand dunes, go to Cedar Point Amusement Park easier, etc. But the best is that I could save a few bucks on some free sheets of OC703.







That stuff just can't be found/ordered in where I live.







I just need 2 more sheets, but even online sources are pricey for just 2 more sheets above the case I already bought.


OK, so I don't really wish to move to Michigan the more I think about it, but if I already lived there.........


----------



## Pain Infliction

I just built my acoustic panels and I am installing my fiberglass insulation into it this weekend. My question is....do I need to put fabric on the backside of the panels if I have them all the way up against the wall without an air gap? Thanks.


----------



## wse




> Quote:
> Originally Posted by *Pain Infliction*  /t/255432/acoustical-treatments-master-thread/9690#post_23610001
> 
> 
> I just built my acoustic panels and I am installing my fiberglass insulation into it this weekend. My question is....do I need to put fabric on the backside of the panels if I have them all the way up against the wall without an air gap? Thanks.



It's better if you do that way you won't have a bunch of fiber glass flying around!


----------



## Noman74656

On a similar note, I want to try and build my own bass traps. I have a a bunch of the echo absorbing panels from Acoustical Solutions. These are the sound absorption stats:


125hz = .08

250Hz = .31

500Hz = 1.32

1KHz = 1.01

2KHz = 1.00

4KHz = .99

NRC = .80


If I put two of the panels behind one another, are the sound absorption coefficients summed for the total predicted value? My pic won't load at the moment


----------



## RossoDiamante




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9660#post_23609697
> 
> 
> 
> Yes. Really. I live in Iowa, so it isn't like it is much colder in winter (depending on where you live). Plus I am a die hard Michigan Wolverines fan. I hate the Iowa "Duckeyes", and could take or leave the Iowa State "Breezy Winds."
> 
> 
> Plus I could go visit the Lake Michigan sand dunes, go to Cedar Point Amusement Park easier, etc. But the best is that I could save a few bucks on some free sheets of OC703.
> 
> 
> 
> 
> 
> 
> 
> That stuff just can't be found/ordered in where I live.
> 
> 
> 
> 
> 
> 
> 
> I just need 2 more sheets, but even online sources are pricey for just 2 more sheets above the case I already bought.
> 
> 
> OK, so I don't really wish to move to Michigan the more I think about it, but if I already lived there.......


 

Go Blue!  From another former Michigander.  I wouldn't want to go back there to live, either.  But maybe I could get my brother to snag that OC703 for me.  He's still there!


----------



## Aaron Smith

For those who may know, I am looking for info on what type of rigid fiberglass is typically used in office partition panels?


I was trolling Craigslist a few weeks ago and saw an ad for "Free office partitions"; the picture showed 6 4'x6' or so panels covered in a nice looking medium gray cloth. Curiosity got the better of me, and since I was driving right by where they were on my way to work I decided to stop in and check them out. They were definitely rigid fiberglass with no silly waferboard or anything like that in them, so I told them I'd head over the next day with my truck to pick them up. Showed up the next day and was told "Oh, I forgot, there's some more in the basement if you want those too."


'Some' more is right -- 24 additional panels to be exact -- I was feeling frisky and ended up making two trips with my F-250 and hauling away _*655 square feet*_ of nice looking cloth covered panels!










The rigid fiberglass is a single piece, 1.5" thick and does not have any sort of plastic facing in front of the cloth...just fiberglass covered with cloth. The panels are the Hon brand and look exactly like these . A little Googling has shown that Johns Manville Whispertone rigid fiberglass in the 6.0 pcf density is commonly used in these types of partition panels -- is there any way to easily determine just exactly what type of fiberglass board is in these?


They have a nice tubular steel frame, and as they are fully finished I'm contemplating many different uses for them if they are suitable (particularly as ceiling panels).


----------



## Flatland2D

I'm planning on building some panels for my upcoming theater build and I've been wondering something. I plan on framing 2' x 4' panels of OC 703 in a 1" x 4" frame. The OC 703 would be flush with the front of the frame leaving about a 1.5" gap between the back of the fiberglass and the wall. If the 1" x 4" frame sat flush on the wall, would that be a problem? Does the back of the panel need to "breathe" with the rest of the room, or can it be somewhat contained? I may end up mounting the frame 0.5" off the wall with some accent lighting behind to create a glow effect, but just thought I'd ask about mounting the other way out of curiosity.


----------



## nickbuol




> Quote:
> Originally Posted by *Flatland2D*  /t/255432/acoustical-treatments-master-thread/9690#post_23619819
> 
> 
> I'm planning on building some panels for my upcoming theater build and I've been wondering something. I plan on framing 2' x 4' panels of OC 703 in a 1" x 4" frame. The OC 703 would be flush with the front of the frame leaving about a 1.5" gap between the back of the fiberglass and the wall. If the 1" x 4" frame sat flush on the wall, would that be a problem? Does the back of the panel need to "breathe" with the rest of the room, or can it be somewhat contained? I may end up mounting the frame 0.5" off the wall with some accent lighting behind to create a glow effect, but just thought I'd ask about mounting the other way out of curiosity.



That is what I am planning on doing (using 1x4 material and having it sit flush on the wall). Hopefully that will be fine.


----------



## wse




> Quote:
> Originally Posted by *Aaron Smith*  /t/255432/acoustical-treatments-master-thread/9690#post_23619509
> 
> 
> For those who may know, I am looking for info on what type of rigid fiberglass is typically used in office partition panels? I was trolling Craigslist a few weeks ago and saw an ad for "Free office partitions"; the picture showed 6 4'x6' or so panels covered in a nice looking medium gray cloth. Curiosity got the better of me, and since I was driving right by where they were on my way to work I decided to stop in and check them out. They were definitely rigid fiberglass with no silly waferboard or anything like that in them, so I told them I'd head over the next day with my truck to pick them up. Showed up the next day and was told "Oh, I forgot, there's some more in the basement if you want those too."
> 
> 
> 'Some' more is right -- 24 additional panels to be exact -- I was feeling frisky and ended up making two trips with my F-250 and hauling away _*655 square feet*_ of nice looking cloth covered panels!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The rigid fiberglass is a single piece, 1.5" thick and does not have any sort of plastic facing in front of the cloth...just fiberglass covered with cloth. The panels are the Hon brand and look exactly like these . A little Googling has shown that Johns Manville Whispertone rigid fiberglass in the 6.0 pcf density is commonly used in these types of partition panels -- is there any way to easily determine just exactly what type of fiberglass board is in these?
> 
> 
> They have a nice tubular steel frame, and as they are fully finished I'm contemplating many different uses for them if they are suitable (particularly as ceiling panels).



Very nice, I should check out Craig's list more often!


----------



## wse




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9690#post_23619889
> 
> 
> That is what I am planning on doing (using 1x4 material and having it sit flush on the wall). Hopefully that will be fine.



1" thick is useless you need at least 2" I use 4" thick panels


----------



## nickbuol

No, no, no. Not 1" thick panels... 1"x4" wood for the frames. 2" thick OC 703 with a 1.5" air gap like the person posting before me.... Placement locations and such are already figured out.


----------



## nickbuol

No, no, no. Not 1" thick panels... 1"x4" wood for the frames. 2" thick OC 703 with a 1.5" air gap like the person posting before me.... Placement locations and such are already figured out.


----------



## Pain Infliction




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9690#post_23619968
> 
> 
> 1" thick is useless you need at least 2" I use 4" thick panels



Why would you say 1" thick panels are useless? I'm pretty sure they would do more than nothing.


----------



## Nightlord

Of course they have some effect, more if they are still kept a few inches off the wall, but it probably won't do as much as you'd hope for.


----------



## nickbuol

A number of "pro" builder will line the entine bottom "half" of the wall with 1" thick material, and then cover the top of the wall with just some batting to fill that same 1" space but leave the top "half" pretty reflective.


Of course those rooms also have lots of bass traps and other acoustical treatments as well.


----------



## Flatland2D

So any input from the experts about what nickbuol and I plan on doing? Does the back of the absorber need to breathe with the rest of the room, or can it be effectively sealed?


In all of the DIY sound absorption panels I've seen, I'm surprised this is not done more frequently or become the "standard". It seems like an easy way to make them and you get the added benefit of a drop in absorption frequency with the air gap.


----------



## ellisr63




> Quote:
> Originally Posted by *Aaron Smith*  /t/255432/acoustical-treatments-master-thread/9690#post_23619509
> 
> 
> For those who may know, I am looking for info on what type of rigid fiberglass is typically used in office partition panels?
> 
> 
> I was trolling Craigslist a few weeks ago and saw an ad for "Free office partitions"; the picture showed 6 4'x6' or so panels covered in a nice looking medium gray cloth. Curiosity got the better of me, and since I was driving right by where they were on my way to work I decided to stop in and check them out. They were definitely rigid fiberglass with no silly waferboard or anything like that in them, so I told them I'd head over the next day with my truck to pick them up. Showed up the next day and was told "Oh, I forgot, there's some more in the basement if you want those too."
> 
> 
> 'Some' more is right -- 24 additional panels to be exact -- I was feeling frisky and ended up making two trips with my F-250 and hauling away _*655 square feet*_ of nice looking cloth covered panels!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The rigid fiberglass is a single piece, 1.5" thick and does not have any sort of plastic facing in front of the cloth...just fiberglass covered with cloth. The panels are the Hon brand and look exactly like these . A little Googling has shown that Johns Manville Whispertone rigid fiberglass in the 6.0 pcf density is commonly used in these types of partition panels -- is there any way to easily determine just exactly what type of fiberglass board is in these?
> 
> 
> They have a nice tubular steel frame, and as they are fully finished I'm contemplating many different uses for them if they are suitable (particularly as ceiling panels).



Nice find! I never thought about those... I will have to keep my eye out on Craiglist too.


----------



## Brad Horstkotte




> Quote:
> Originally Posted by *Flatland2D*  /t/255432/acoustical-treatments-master-thread/9690#post_23623226
> 
> 
> So any input from the experts about what nickbuol and I plan on doing?



It should work fine


----------



## nickbuol

Thanks Brad!


----------



## Flatland2D

In addition to the sound absorbing panels I have planned, I've also been think about adding a QRD diffuser. My room is roughly 13' x 23' and I have room to put a diffuser in the middle of the back wall. Preliminary measurements would be roughly 2' x 4' and 6" deep.


Is one diffuser enough for a room of this size? I know that's sort of a loaded question and the answer is probably "it depends", but since absorbers and diffusers work differently, do you need an equal number of diffusers and absorbers, or can one diffuser do the trick? I could probably fit in some smaller, maybe 2' x 2' diffusers on the side walls (one per side) in the back if necessary. Might have to compromise on a 4" depth, though.


----------



## Nightlord

I would say 'definitely no'. But you need to know that I'm a firm believer in diffusion and think you should count in square yards/meters rather than any other unit.


----------



## Flatland2D

I probably didn't ask my question as clearly as possible, so I just wanted to clarify. You think one diffuser is definitely not enough for a room of this size?


I can give square yards if it will help.


----------



## Nightlord




> Quote:
> Originally Posted by *Flatland2D*  /t/255432/acoustical-treatments-master-thread/9690#post_23624778
> 
> 
> I probably didn't ask my question as clearly as possible, so I just wanted to clarify. You think one diffuser is definitely not enough for a room of this size?
> 
> 
> I can give square yards if it will help.



Don't blame yourself, I'm Swedish and we probably don't match 100% languagewise, so put the blame on me.


One diffuser will help - if it's five square yards big. The one you mentioned is a few square feet and has to hit the exact sweet spot to have any effect, but it will hardly have any effect for all seats. May be good enough for you, me - I think you need more/bigger.


----------



## Aaron Smith




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9690#post_23619965
> 
> 
> Very nice, I should check out Craig's list more often!





> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/9690#post_23623289
> 
> 
> Nice find! I never thought about those... I will have to keep my eye out on Craiglist too.



Thanks guys!


A few years ago, I had helped a buddy that owns a cleaning company move a bunch of these for his big hospital account -- I didn't take the time to inspect them but could tell they were pretty much just rigid fiberglass covered with cloth. A few weeks later some popped up on Craigslist; after a little research I found out that many of these had Whispertone board in them, and that a few guys had used this stuff successfully as acoustic treatment. I missed those, but kept a vigilant lookout. It's amazing the things you can see on CL for free...just missed out on a _*half semi-trailer load*_ of 'acoustic fiberglass' a few weeks ago (not even sure what it was as the seller didn't describe it very well, but I was contact #2 and he said the 1st guy that called said he could bring his 28' enclosed trailer over in 30 minutes and "would take it all").


The stuff I have looks very similar to the 2" OC705 I have here, just .5" thinner.


Would be _really nice_ to know just exactly what it is.


----------



## Flatland2D




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9690#post_23624816
> 
> 
> 
> 
> Quote:
> Originally Posted by *Flatland2D*  /t/255432/acoustical-treatments-master-thread/9690#post_23624778
> 
> 
> I probably didn't ask my question as clearly as possible, so I just wanted to clarify. You think one diffuser is definitely not enough for a room of this size?
> 
> 
> I can give square yards if it will help.
> 
> 
> 
> 
> Don't blame yourself, I'm Swedish and we probably don't match 100% languagewise, so put the blame on me.
> 
> 
> One diffuser will help - if it's five square yards big. The one you mentioned is a few square feet and has to hit the exact sweet spot to have any effect, but it will hardly have any effect for all seats. May be good enough for you, me - I think you need more/bigger.
Click to expand...


Thanks for the explanation. I still have a lot of learning to do with this. I have a pretty good idea for what I'm planning on doing for absorption, but diffusion is still up in the air.


Sent from my Nexus 7 using Tapatalk 4


----------



## lecheking

Quick question you guys! When you install your DIY Bass Trap... Is This 703 going to float around and be bad to have in a home after installation.







My father is being a stickler, I tried telling him people use this stuff all the time for Acoustics. He's not having it though. He's convinced Foam is the way to go because it doesn't mean having Fiberglass in the House ... Help me out LOL


----------



## LowellG

I will tell you in about a week, My 1" panels are in and I have 6, 4" ones coming too. However, from everything I have read, so long as I wrap them, they will be fine. I am actually going to shop for fabric tonight. I used something called Kona cotton to wrap my Roxul Rockwool in. I am looking for the same thing.


----------



## lecheking




> Quote:
> Originally Posted by *LowellG*  /t/255432/acoustical-treatments-master-thread/9690#post_23630019
> 
> 
> I will tell you in about a week, My 1" panels are in and I have 6, 4" ones coming too. However, from everything I have read, so long as I wrap them, they will be fine. I am actually going to shop for fabric tonight. I used something called Kona cotton to wrap my Roxul Rockwool in. I am looking for the same thing.


Awsome! Sounds like a plan!


----------



## wse




> Quote:
> Originally Posted by *Flatland2D*  /t/255432/acoustical-treatments-master-thread/9690#post_23627070
> 
> 
> Thanks for the explanation. I still have a lot of learning to do with this. I have a pretty good idea for what I'm planning on doing for absorption, but diffusion is still up in the air.



For diffusion get some of those, I did and I love them









http://www.vicoustic.com/vn/Homecinema/ProdutoInfo.asp?Id=106


----------



## Pain Infliction

wse.....What is the cost of one of those?


----------



## Pain Infliction




> Quote:
> Originally Posted by *LowellG*  /t/255432/acoustical-treatments-master-thread/9690#post_23630019
> 
> 
> I will tell you in about a week, My 1" panels are in and I have 6, 4" ones coming too. However, from everything I have read, so long as I wrap them, they will be fine. I am actually going to shop for fabric tonight. I used something called Kona cotton to wrap my Roxul Rockwool in. I am looking for the same thing.



I bought some burlap from ATS Acoustics. Check them out.
http://www.atsacoustics.com/cat--Fabric--107.html


----------



## lecheking

What about MicroSuede to cover your Panels and Traps







? Seems like a good material to reflect, as well as keep that nasty FiberGlass from falling out into the room !?







Experience Anyone ??? Lol.


----------



## Pain Infliction

You do not want material to reflect. You want the sound to go through. Also, if you or your Dad is concerned about the fiberglass, there are other options.


----------



## lecheking




> Quote:
> Originally Posted by *Pain Infliction*  /t/255432/acoustical-treatments-master-thread/9690#post_23633653
> 
> 
> You do not want material to reflect. You want the sound to go through. Also, if you or your Dad is concerned about the fiberglass, there are other options.


Sorry! Yes Absorb! I been reading This thread non-stop for 2 days now







. I really like the idea of 705 and 703. Seems to be the best absorbers. Which other options other than fiberglass do you speak of? And would you suggest Microsuede at all ?







Thanks for the Help !


----------



## Pain Infliction

Roxul safe n sound is mineral wool and can be used. I don't know if microsuede is AT? I agree that it would look nice but I never heard of people using it so that means its probably not AT.


----------



## lecheking




> Quote:
> Originally Posted by *Pain Infliction*  /t/255432/acoustical-treatments-master-thread/9720#post_23633733
> 
> 
> Roxul safe n sound is mineral wool and can be used. I don't know if microsuede is AT? I agree that it would look nice but I never heard of people using it so that means its probably not AT.


Would you by any chance know the how much this absorbs compared to 703? It is odd that people haven't tried microsuede. I mean... It's probably not AT for high frequencies (1k) but for lower HZ I'm sure it's more than fine... I might just have to try it. It's hard to make this look visually pleasing. Haha


----------



## nickbuol




> Quote:
> Originally Posted by *lecheking*  /t/255432/acoustical-treatments-master-thread/9720#post_23633773
> 
> 
> Would you by any chance know the how much this absorbs compared to 703? It is odd that people haven't tried microsuede. I mean... It's probably not AT for high frequencies (1k) but for lower HZ I'm sure it's more than fine... I might just have to try it. It's hard to make this look visually pleasing. Haha



Some online vendors offer microsuede ATS is one. I had them send me some fabric samples and my head would explode I think before I could ever blow a bit of air through it...


----------



## LowellG




> Quote:
> Originally Posted by *lecheking*  /t/255432/acoustical-treatments-master-thread/9720#post_23633773
> 
> 
> Would you by any chance know the how much this absorbs compared to 703? It is odd that people haven't tried microsuede. I mean... It's probably not AT for high frequencies (1k) but for lower HZ I'm sure it's more than fine... I might just have to try it. It's hard to make this look visually pleasing. Haha



Here is the acoustic performance of a bunch of products. click the link if you want to see it spread out better.

http://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html 



Product Name Density

lbs/ft3 125 Hz. 500 Hz. 1000 Hz. 4000 Hz. NRC Rigidity Price/sq.ft.

Roxul AFB 2" 2.5 lb. 0.28 1.09 1.09 1.07 0.95 Flexible $0.75

Plus: Excellent sound absorption, low cost. Best choice when strength and rigidity are not needed. Minus: Flexible like a batt or blanket. Not a problem if supported by a frame, fabric, etc.


Roxul Rockboard 60 6 lb. 0.32 1.06 1.02 1.04 0.95 Rigid $1.08

Plus: Excellent sound absorption. Lower cost than 703 and 705. Good strength and rigidity. Best choice for an effective, affordable, rigid product. Minus: More expensive than AFB if you don't need a rigid material.


Roxul Rockboard 80 8 lb. 0.43 0.90 0.97 1.00 0.90 Rigid $1.50

Plus: Excellent low freq sound absorption. Lower cost than 705. Good strength and rigidity. Minus: Does not absorb mid to high frequencies quite as well as Rockboard 60.


ATS Acoustics Rigid Fiberglass Board 1" 3 lb. 0.06 0.75 0.99 1.02 0.75 Rigid $0.98

Plus: An exact substitute for 703 at a better price. Minus: You get more sound absorption from a 2-inch material.


ATS Acoustics Rigid Fiberglass Board 2" 3 lb. 0.29 1.11 1.13 1.03 1.00 Rigid $1.33

Plus: An exact substitute for 703 at a better price. Minus: A little more expensive than AFB and Rockboard 60 for the same sound absorption.


Knauf ECOSE® 1" 3lb 3 lb. 0.08 0.62 0.88 0.99 0.65 Rigid $1.02

Plus: A more eco-friendly, formaldehyde-free substitute for 703 at a similar price.


Knauf ECOSE® 2" 3lb 3 lb. 0.29 1.11 1.13 1.03 1.00 Rigid $1.44

Plus: An eco-friendly, formaldehyde-free sustainable insulation board. Similar to Owens Corning 703 insulation.


Knauf ECOSE® 2" 6lb 6 lb. 0.32 1.08 1.06 1.04 1.00 Rigid $2.48

Plus: An eco-friendly, formaldehyde free sustainable insulation board.


Knauf ECOSE® Black Acoustical Board 2" 6 lb. 0.33 1.07 1.07 1.06 0.95 Rigid $2.92

Plus: An eco-friendly, formaldehyde free sustainable insulation board. Designed as an acoustical/visual barrier for wall and ceilings where black surface is required.


Owens-Corning 703 4" 3 lb. 0.84 1.24 1.08 0.97 1.15 Rigid $3.29

Plus: Good low frequency absoroption, strong and rigid. Minus: More expensive than two layers of Rockboard or AFB.


Owens-Corning 703 2" 3 lb. 0.17 1.14 1.07 0.98 1.00 Rigid $1.44

Plus: Well known product. Good for small projects where cost is not a big concern. Minus: More expensive than AFB and Rockboard 60 for the same sound absorption.


Owens-Corning 703 1" 3 lb. 0.11 0.68 0.90 0.96 0.70 Rigid $0.97

Plus: Familar brand name, moderate strength and rigidity. Minus: High cost, lower sound absorption (NRC) because it is only 1" thick.


Owens-Corning 705 2" 6 lb. 0.16 1.02 1.01 0.99 0.95 Rigid $2.48

Plus: Strongest surface resists damage (like stiff styrofoam). Minus: Expensive. Rockboard 60 is usually a better choice.


Owens-Corning 705 1" 6 lb. 0.02 0.63 0.85 0.95 0.65 Rigid $1.69

Plus: Familar brand name, good strength and rigidity. Minus: High cost, lower NRC because it is only 1" thick.


Applegate Recycled Cotton 2" 2.5 lb. 0.27 1.17 1.15 1.06 1.05 Flexible $1.54

Plus: Excellent sound absorption. High recycled content makes it the most eco-friendly choice. Minus: Flexible like a batt or blanket. Not a problem if supported by a frame, fabric, etc.


Owens-Corning 703 FRK 2" 3 lb. 0.63 0.95 0.79 0.35 0.75 Rigid $1.85

Plus: Excellent sound absorption. Most popular material for acoustic absorption. Minus: The cost is higher that other insulation products, and some high-end frequencies will be reflected.


----------



## lecheking




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9720#post_23634254
> 
> 
> 
> 
> Quote:
> Originally Posted by *lecheking*  /t/255432/acoustical-treatments-master-thread/9720#post_23633773
> 
> 
> Would you by any chance know the how much this absorbs compared to 703? It is odd that people haven't tried microsuede. I mean... It's probably not AT for high frequencies (1k) but for lower HZ I'm sure it's more than fine... I might just have to try it. It's hard to make this look visually pleasing. Haha
> 
> 
> 
> 
> Some online vendors offer microsuede ATS is one. I had them send me some fabric samples and my head would explode I think before I could ever blow a bit of air through it...
Click to expand...

Thanks for this description! Lol. Yeah ... Idk why ,but uhhh.... I don't think microsuede would be the best fabric after all







What did all you guys choose for your fabric or would recommend for the "Newbies"


----------



## nickbuol




> Quote:
> Originally Posted by *lecheking*  /t/255432/acoustical-treatments-master-thread/9720#post_23636597
> 
> 
> Thanks for this description! Lol. Yeah ... Idk why ,but uhhh.... I don't think microsuede would be the best fabric after all
> 
> 
> 
> 
> 
> 
> 
> What did all you guys choose for your fabric or would recommend for the "Newbies"



I think that any of the common "burlap" type fabrics are probably the most easily effective.


However, I am going with printable fabric (Kona Cotton from SpoonFlower) as used in this link:
DIY Custom-Printed Movie Poster Acoustic Panels - Cheap! 


I am going to get some custom artwork printed instead of movie posters, but it will be from the same place. There are some tests in that thread that show it to be good acoustically, and it looks less "industrial" or "commercial" than the GOM or burlap material.


----------



## tcramer

There's also the recycled denim insulation which is even 'cleaner' than roxul, they say you can install it without gloves, mask, long sleeves etc. I imagine roxul could still cause irritation given the nature of rock wool.


Never used it or heard much about it. Definitly costs more than fiberglass.


----------



## Pain Infliction

Somebody that has a studio said the same thing. He was suppose to email me a link to it but he never did so I went with 703.


----------



## wse




> Quote:
> Originally Posted by *Pain Infliction*  /t/255432/acoustical-treatments-master-thread/9690#post_23630064
> 
> 
> wse.....What is the cost of one of those?



$350


----------



## LowellG




> Quote:
> Originally Posted by *tcramer*  /t/255432/acoustical-treatments-master-thread/9720#post_23637870
> 
> 
> There's also the recycled denim insulation which is even 'cleaner' than roxul, they say you can install it without gloves, mask, long sleeves etc. I imagine roxul could still cause irritation given the nature of rock wool.
> 
> 
> Never used it or heard much about it. Definitly costs more than fiberglass.



If you price Roxul vs 703 of the size, Roxul is cheaper.


----------



## LowellG

Getting ready to build my bass traps this weekend with 4" OC 703. Should 100% cotton sheets be fine as the fabric?


Also, I am putting several panels up. Some with Roxul AFB and movie posters as addressed in another thread. The others will be some OC 703 1". I only have 4 sheets, so what would be better. Make 4, 2'x4' panels, or cut them in half and make 4, 1'x4' panels that are 2" thick?


----------



## Pain Infliction

For looks...the 2'x4'. For effectiveness......1'x4'


The fabric needs to be AT.


----------



## LowellG




> Quote:
> Originally Posted by *Pain Infliction*  /t/255432/acoustical-treatments-master-thread/9720#post_23654819
> 
> 
> For looks...the 2'x4'. For effectiveness......1'x4'
> 
> 
> The fabric needs to be AT.



I was thinking 100% cotton sheets for both those and the bass traps. I am using the Kona Cotton from spoon flower for my Roxul AFB panels.


PS. I am going for effectiveness. I just didn't know if a broad surface was better.


----------



## HopefulFred

If you're trying to trap bass, the cotton sheets will be fine. If you want to absorb specular reflections (first reflection point treatment, or similar) you need to asses your needs a little (and I still think the cotton is probably okay). Most times I think it would be best to use the thicker treatment. On the other hand, if the room is too live in the midrange and higher frequencies, but okay in the lower midrange (this is not a very likely scenario), you can absorb more of the high frequency stuff by spreading the material across more of the wall. The thickness dictates the low frequency effectiveness of the absorption, while the area of the wall covered relates to the overall liveliness of the room.


----------



## BasementBob




> Quote:
> Originally Posted by *Noman74656*  /t/255432/acoustical-treatments-master-thread/9690#post_23617171
> 
> 
> On a similar note, I want to try and build my own bass traps. I have a a bunch of the echo absorbing panels from Acoustical Solutions. These are the sound absorption stats:
> 
> 
> 125hz = .08
> 
> 250Hz = .31
> 
> 500Hz = 1.32
> 
> 1KHz = 1.01
> 
> 2KHz = 1.00
> 
> 4KHz = .99
> 
> NRC = .80
> 
> 
> If I put two of the panels behind one another, are the sound absorption coefficients summed for the total predicted value? My pic won't load at the moment



No. You can't sum the values.


See this page to get a feel for what happens as you use thicker wool
http://www.bobgolds.com/AbsorptionCoefficients.htm 


'wool' is glasswool (aka fiberglass), or rockwool or cottonwool. (although open cell foam would behave similarly)


----------



## BasementBob




> Quote:
> Originally Posted by *Pain Infliction*  /t/255432/acoustical-treatments-master-thread/9720#post_23633733
> 
> 
> Roxul safe n sound is mineral wool and can be used.


The most common Safe N Sound is soft flexable (like fluffy fiberglass pink), and would require some sort of a frame to support the shape and fabric cover and hanging. It absorbs fine though.


----------



## BasementBob




> Quote:
> Originally Posted by *LowellG*  /t/255432/acoustical-treatments-master-thread/9720#post_23654862
> 
> 
> I just didn't know if a broad surface was better.



You might want to look at multiple frequency Wallace Clement Sabine's reverberation equation.

Reverberation time RT60 = k * V / A


At least to answer the question about what will happen with a broad surface vs not.

(There are other issues affecting sound in a room, and some debate about RT60 in a small room, but it will explain 'broad surface')


For lots of examples see "How to Build a Small Budget Recording Studio from Scratch, 3rd edition" by Mike Shea and F. Alton Everest.


That said, {measurement, diagnosis, treatment} is usually a good algorithm.


----------



## rthompson10

Hello,


Need so advice on open floorplan theater space in basement


17.5 feet wide front wall -59x134 screen is here; 19 feet long with 2 rows of leather chairs


U shape- open back- half wall with aisle on each side dividing theater area from rest of basement .All speakers are in- wall, including front. Screen is AT, about 3 " off wall with screen covering center channel


This section is carpeted.


I'm trying to improve sound- essentially my goal is to not have to turn volume down when LFE kicks in- Subwoofer are in front of room in front of screen.


Was on a plan to do panels on side walls at reflection points- starting point is roughly 6 feet worth(3 2x4 panels) on each side wall.


Given that room has open back what steps are best in this environment(effectiveness vs dollar. I have room to put stuff behind screen that covers half of front wall based on square footage- yes?

Bass traps in front corners?


Again with open back- albeit with chairs and 1/2 wall blocking- I know I have limitations


ThaNKS!


RT


----------



## Pain Infliction

Have any pics? 17.5' wide screen is huge!!!!







I thought mine was big at just under 12'.


----------



## rthompson10

Clarification. The wall where the screen is located is here- Screen is 59x134


----------



## Noman74656




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9720#post_23654925
> 
> 
> No. You can't sum the values.
> 
> 
> See this page to get a feel for what happens as you use thicker wool
> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> 
> 'wool' is glasswool (aka fiberglass), or rockwool or cottonwool. (although open cell foam would behave similarly)



Dang! That nixes that idea. Thanks for the information in the link. I just purchased some corner foam traps from the same company that should arrive next week.


----------



## jbrown15

Quick question without going threw this entire thread, but I'm assuming I could use Roxel safe n sound to build triangular corner bass traps to use on my front wall to go behind my false wall/AT screen?


But would it work as well OC703 or would I be better off just using OC703?


Thanks in advance.


----------



## BasementBob




> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9720#post_23682935
> 
> 
> I'm assuming I could use Roxel safe n sound to build triangular corner bass traps to use on my front wall to go behind my false wall/AT screen?
> 
> 
> But would it work as well OC703 or would I be better off just using OC703?



All the Roxul Safe‘n’Sound I've ever seen is soft flexible (like a fluffy fiberglass pink batt), although a friend of mine found some rigid.

The soft flexible kind you'd need to build a frame for, whereas rigid can be it's own frame and only needs to be wrapped.


As for Roxul Safe‘n’Sound absorption effectiveness relative to OC703, please see
http://www.bobgolds.com/AbsorptionCoefficients.htm 

to compare them.


----------



## sdurani




> Quote:
> Originally Posted by *rthompson10*  /t/255432/acoustical-treatments-master-thread/9720#post_23680668
> 
> 
> I'm trying to improve sound- essentially my goal is to not have to turn volume down when LFE kicks in- Subwoofer are in front of room in front of screen.


Can you move the subwoofers to the quarter points of room width? This will help smoothen the frequency response across the seating area and cut down on some of the boominess.


The open back in your room is the ultimate bass trap/absorber, like an acoustic version of the roach motel: sound goes in but doesn't come out. Bass traps in front corners wouldn't hurt as well covering as much of the front wall with broadband absorption as you can.


----------



## rthompson10

Sdurani,

Thanks!

If you are talking quarter points along front wall I can do that. They may be there now

Rt


----------



## sdurani

Robert,


Yes, on the front wall, place the middle of your subwoofer drivers 1/4 room width from the left and right walls. Should cut down on peaks & dips at roughly 32Hz and 65Hz across your seating.


The room correction system in your receiver will thank you for the improved seat-to-seat consistency (makes it easier to EQ problems if they are similar from seat to seat).


----------



## Nightlord

It will also put the virtual mirrored subwoofers (side wall reflex) equidistant.


----------



## lbrown105

I am looking for advice on drop ceiling tiles for a drop ceiling with std 2X2 grid system. I don't know what kind of tiles are currently in the grid since they were here when I bought the house. They seem to be the compressed fiber board type commonly seen in rec rooms. I am trying to use the ceiling as a broad band bass trap as much as possible and also reduce first reflections from the ceiling, especially up front.. I have R-19 plastic wrapped insulation above the drop ceiling and that is about as thick as I can go. Any recomendations or examples of good drop ceiling tiles I could consider to improve bass trapping? Looks like basotech material is becoming more popular for sound absorption, but bot sure if that is what I should look at. I want as much low freq absorption as possible and can go as thick as 6inches.


any advice is appreciated.


----------



## Skylinestar

Currently, my living area is in "L" shape, which then opens to another dining room and a kitchen (total ~10,000 cu ft). I am planning to build a wall to split the "L' shape into just "|" shape...ie making the living room a rectangular room (~4000 cu ft), separated from the rest of the area.

What will I gain in terms of acoustic? I'm sure by closing the space, the bass will pressurize the room easier (less cu ft). Will I get better (smoother) frequency response?

I don't want to build a wall...then end up with worse frequency response that my family and I will regret forever.

By the way...this is my current bass frequency response. This is the best I can get after all the EQ tweaking and subwoofer placement.


----------



## Nightlord

Nothing at all to complain about that one. Looks very good, nice slope.


----------



## Skylinestar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23712876
> 
> 
> Nothing at all to complain about that one. Looks very good, nice slope.


I'm just worried whether adding a wall partition will greatly affect the frequency response


----------



## Nightlord




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9750#post_23713009
> 
> 
> I'm just worried whether adding a wall partition will greatly affect the frequency response



Well, it will change and you will have some work to do to tune it in again, but there's nothing saying it will have to be worse after that.


----------



## Skylinestar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23713246
> 
> 
> Well, it will change and you will have some work to do to tune it in again, but there's nothing saying it will have to be worse after that.


  

The diagram shows a layout of my living room (not exactly a closed room) where all my HT stuffs are in. It's a family area. It's open to the rest of the house...total about 10,000 cu ft. Which such a big space, it's impossible to pressurize all the air even though there are 2 units of Rythmik FV15HP. I'm planning to build a wall (the orange line in the diagram) to close off the area. By closing off the area, I can reduce to space to ~3,500 cu ft. Better bass? I've also read about articles saying that smaller room has worse acoustic than a bigger room. Will this happen to me?


I'm only concern with serious nulls and ringing that will took me forever to tune. The subwoofer placement is limited due to WAF though.


One more thing...by adding that wall, will I get better surround sound?


----------



## Nightlord

Well, the lowest mode(s) will probably disappear, so if you've adjusted that, you need to undo that. A lot of the basic modes will be the same as you keep most the dimensions. I don't know how much reverberation you've had from your L vs how much it has worked as a trap.


You'll definitely get to keep more bass energi in the room, so RT60 in that range will go up.


What's the main reason for the wall? (Sorry for not backing up in the thread to find out while typing this) If it's only for looks then you could possibly build a part of it a bit acoustically transparent and still keep it as your basstrap.










I think both surround and the sound in total will get more left-right balanced with a more symmetrical room.


Subwoofer placement is where I want them. You get maximum out of them there, but yes - you do excite the modes very well, but at the same time they are more defined for taking care of.


I have similar L shape in my livingroom, also with an opening in the back (surround side) wall into my kitchen, but I think I'd gone for the chance to close it off too if possible. Now, I'm building a cinema in a less compromised room, so livingroom will stay as is.


----------



## Skylinestar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23715528
> 
> 
> What's the main reason for the wall?


Perhaps better bass feeling? Please enlighten me.

I've read many bass threads about bass heavy movies giving you the balls tickling, hair moving, body shuddering feel...but those ain't gonna happen in a big space. Therefore...I'm asking opinions about the effect of the wall. By closing off the space, the cu ft will be reduced from ~10,000 to ~3,500...big reduction there.


----------



## Nightlord

Nothing is impossible. Try 8 subs instead of 2 for instance. The need to pressurize is mostly important if you want to dig extremely deep.


The first thing to ask is... Do you really listen loud enough for those effects to come into play? Don't underestimate just how loud some cinema and music nerds play. Have you used your subwoofers to the limit of their excursion?


----------



## Skylinestar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23716132
> 
> 
> Nothing is impossible. Try 8 subs instead of 2 for instance. The need to pressurize is mostly important if you want to dig extremely deep.
> 
> 
> The first thing to ask is... Do you really listen loud enough for those effects to come into play? Don't underestimate just how loud some cinema and music nerds play. Have you used your subwoofers to the limit of their excursion?


\

I watch movies at -10dB.


----------



## Nightlord

Ok. So what the guys playing +5 experience we will never know no matter how we rebuild our rooms.










Add two more subwoofers and put buttkickers in the chairs and leave the wall as it is could be an alternative...


----------



## Skylinestar




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23717050
> 
> 
> Ok. So what the guys playing +5 experience we will never know no matter how we rebuild our rooms.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Add two more subwoofers and put buttkickers in the chairs and leave the wall as it is could be an alternative...


Building a wall is 10x cheaper than buying 2 more FV15HP subs.

I have just bought a buttkicker advance kit. gonna setup later when I'm free


----------



## BasementBob

If at all possible, keep the room over 1500 cubic feet.

A room below 2,000 cubic feet [on the order of 14x18x8’ in size] is a very small room acoustically.

Rooms which are above about 5,000 cubic feet [on the order of 20x25x10’ in size] in volume are of sufficient size to begin considering a full fledged reverberant field.


----------



## rthompson10

Hello,


Comparing 2 commercial bass trap products NRC


Prod A Prod B

125 0.94 0.89

250 1.29 1.84

500 1.19 1.63

1000 1.05 1.07

2000 1.06 0.8



How to compare? Concerned about the big diff at 250 and 500Mhz- thats mid frequency right?- so high mid absorption? Confused.....


Thanks


RT


----------



## Nightlord

I wonder how you actually absorb more than 100%. Seems more a figure of how much overkill the thickness is for those frequencies.


I'd gone for product A on those numbers, unless I worried about dampening too much up in the 2k and above so the lower absorption up there would be a selling point for B.


----------



## BasementBob




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23722613
> 
> 
> I wonder how you actually absorb more than 100%.



"The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. ... A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material."

-- Jeff D. Szymanski



> Quote:
> Originally Posted by *rthompson10*  /t/255432/acoustical-treatments-master-thread/9750#post_23721613
> 
> 
> Comparing 2 commercial bass trap products NRC
> 
> 
> Prod A Prod B
> 
> 125 0.94 0.89
> 
> 250 1.29 1.84
> 
> 500 1.19 1.63
> 
> 1000 1.05 1.07
> 
> 2000 1.06 0.8


To me, those are not bass traps, but are midrange absorbers.


A bass guitar's strings are {98 Hz, 73 Hz, 55 Hz, 41 Hz}.

So, to me a bass trap would be something that works primarily in the 30hz to 100hz range -- which is a range that most reverberation chambers are notoriously bad at measuring. (particularly 20hz to 50hz)


Listen to

- http://onlinetonegenerator.com/subwoofer.html 

- http://onlinetonegenerator.com/hearingtest.html 

to know what frequencies are what.


Most 'tuned' bass traps are some sort of resonant absorber (e.g. RPG Modex Corner), either by membrane or Helmholtz/slat -- that take advantage of high pressure/low particle velocity.

Some corner absorbers are called bass traps because they are practical even down between 63hz and 100hz, such as the studiotips superchunk and megaLENRDs; and others have a plastic film membrane over them to reflect high frequencies.


----------



## Nightlord




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9750#post_23722719
> 
> 
> "The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. ... A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material."
> 
> -- Jeff D. Szymanski



Ok, that's different numbers from the one I'm used to then.


----------



## coolgeek

I stumbled upon this thread while researching acoustic treatment for my basement HT. But as is always the case, sometimes the more you learn, the more confusing it is as different people gives you different opinions.


So, a couple of noobie question here:


1. Bass Traps.


I was told to place 4 bass traps in all 4 corners of the room (but not behind the screen.


This is how my front wall looks like


10 feet

- - - - - - - - - - - - - - - - - - - - - - - - - -

| a [Subwoofer] a|

| [L] [C] [R] | 
- - - - - - - -

|b b |

| |

| |



So, should I place bass traps in location (a)?? That is entirely behind the AT screen and where i'll be placing my subwoofer, corner loaded as you can see. So, the question is, if i placed bass traps in the positions (a), would they absorb all my bass and thus lowering my bass?

Now, I know (b) might be good locations (or I might be wrong)


Also, i was told the simplest bass traps I can make is just get a piece of thick wood like 1 inch thick, and just cover the corner from bottom to the top


----------



## Nightlord

Well, that's not so strange... and YOUR ROOM is the basis of everything. And you (as in anyone) cannot describe in such detail that anyone (as in the best acoustician in the world) could tell you exactly what to do. Getting him inside your room with all the gear he needs is a partly different matter.


So, take suggestions as they are.... suggestions. Not everything will work, but it doesn't mean that if your room had been a bit different it wouldn't have... And it's definitely a field where the more you learn teaches you the humility of understanding how little you actually know.... so prepare for trying different things....


----------



## coolgeek

OK, looks like my attempt at drawing my room is messed up by vbulletin... anyways,


here's the question again.


Should you place a bass trap next to the subwoofer? Wouldn't that absorb all the bass from the sub??? Basically, the best 2 corners for me to place bass traps are the the front wall, behind the AT screen, which is also where i place my subwoofer. So, should i or should i not place the bass traps there?


----------



## BasementBob




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/9750#post_23740047
> 
> 
> Should you place a bass trap next to the subwoofer? Wouldn't that absorb all the bass from the sub??? Basically, the best 2 corners for me to place bass traps are the the front wall, behind the AT screen, which is also where i place my subwoofer. So, should i or should i not place the bass traps there?



Assuming your room is rectangular, type in your room dimensions into:
http://www.hunecke.de/en/calculators/room-eigenmodes.html 

And click on all the radiobuttons.


The initial best places to put your subwoofer(s) would be the white or grey spots, such as 1/3 room spots away from doors. (the black spots are bad places) [There are other, better, algorithms for where to put subwoofers, such as "The Crawl Test"]


Corner bass traps (like studiotips superchunks):

a) can only absorb sound that gets to them. Subwoofers send sound omnidirectionally to the entire room -- what percentage of the room surface would be covered by absorbers? In other words very little would be absorbed by the corner absorbers.

b) can only absorb a portion of the sound that hits them. They're not 100% efficient (absorptive)


So, the answer to "Wouldn't that absorb all the bass from the sub?" the answer is: no.


The advantage of corner absorbers is similar to why you don't want to put a powerful subwoofer in a tri-corner. Room modes are all active in tri-corners. (If you have a wimpy subwoofer and a huge volume room, putting the subwoofer in the tri-corner may make it appear louder, but unevenly)

So with a subwoofer in a tri-corner it would excite all the room modes (good for acoustics testing, lousy for movies). Putting an absorber in a tri-corner depresses all the room modes (good for movies). An excited room mode results in either hearing that tone louder than it should be, or not hearing that tone, depending upon seating position.


A more interesting concern would be the front towers -- which corner absorbers might make a measurable tonal difference to. They may be built assuming there are no absorbers near them, and their bass drivers balanced against their mid-range and tweeters assuming there's a wall behind them.


----------



## BasementBob




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/9750#post_23740001
> 
> 
> Also, i was told the simplest bass traps I can make is just get a piece of thick wood like 1 inch thick, and just cover the corner from bottom to the top



I wouldn't do that.


At best ,that's just making the room smaller -- similar to drywall. Less volume is usually not good.

Most likely it will do nothing, which is a waste.


It seems a bit thick to be a resonant absorber -- and even if it were you have no idea what frequencies it would be effective on, so what's the point.


----------



## Nightlord

BasementBob - for me reading that is quite funny, not that you're wrong, but my sound system is actually designed the other way around... Subwoofers are designed for corner loading while the fronts are designed for NOT having a wall behind ( meaning a heavily dampened one ).


----------



## BasementBob




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23740759
> 
> 
> the fronts are designed for NOT having a wall behind


Yes. I've seen those.


> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9750#post_23740759
> 
> 
> Subwoofers are designed for corner loading


How does that work? How do you bypass the physics of room modes?


----------



## coolgeek




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9750#post_23740618
> 
> 
> Assuming your room is rectangular, type in your room dimensions into:
> http://www.hunecke.de/en/calculators/room-eigenmodes.html
> 
> And click on all the radiobuttons.
> 
> 
> The initial best places to put your subwoofer(s) would be the white or grey spots, such as 1/3 room spots away from doors. (the black spots are bad places) [There are other, better, algorithms for where to put subwoofers, such as "The Crawl Test"]
> 
> 
> Corner bass traps (like studiotips superchunks):
> 
> a) can only absorb sound that gets to them. Subwoofers send sound omnidirectionally to the entire room -- what percentage of the room surface would be covered by absorbers? In other words very little would be absorbed by the corner absorbers.
> 
> b) can only absorb a portion of the sound that hits them. They're not 100% efficient (absorptive)
> 
> 
> So, the answer to "Wouldn't that absorb all the bass from the sub?" the answer is: no.
> 
> 
> The advantage of corner absorbers is similar to why you don't want to put a powerful subwoofer in a tri-corner. Room modes are all active in tri-corners. (If you have a wimpy subwoofer and a huge volume room, putting the subwoofer in the tri-corner may make it appear louder, but unevenly)
> 
> So with a subwoofer in a tri-corner it would excite all the room modes (good for acoustics testing, lousy for movies). Putting an absorber in a tri-corner depresses all the room modes (good for movies). An excited room mode results in either hearing that tone louder than it should be, or not hearing that tone, depending upon seating position.
> 
> 
> A more interesting concern would be the front towers -- which corner absorbers might make a measurable tonal difference to. They may be built assuming there are no absorbers near them, and their bass drivers balanced against their mid-range and tweeters assuming there's a wall behind them.



Thanks,


But what's a TRI-Corner?


----------



## HopefulFred

A tri-corner is where three surfaces come together at a point. Two walls and either a ceiling or floor make a tri-corner. This defines what is also known as 1/8th-space.


----------



## Nightlord




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9750#post_23741248
> 
> 
> Yes. I've seen those.
> 
> How does that work? How do you bypass the physics of room modes?



You take the standpoint that handling the modes is worth the hassle for the benefit you get from cornerloading subs


I have no apparent problems in my livingroom (untreated) but it could be helped by opening up into the rest of the house in an nonsymmetrical way, in the cinema there's quite a bit of absorbent put in as a thick rear wall besides the bass trap in the riser and the dampening on the front wall.


----------



## Nightlord




> Quote:
> Originally Posted by *pepar*  /t/255432/acoustical-treatments-master-thread/9540#post_23395165
> 
> 
> Below the Schroeder frequency, room mode range, I don't thing there is a "front" or for that matter a "rear" to the room. So bass should be trapped anywhere one has the space to place traps. At this time I have SSC-style bass traps only in the front of the room; it sounds stunning. If I ever get a round tuit, I will add some more in the rear.
> 
> 
> Jeff



There is a direction from where the initial wavefront comes from. If you play a stable test tone, then I agree, but music is more transient in nature, so consider a single woofer kick.... You don't want the initial arrival to be dampened, but you will want the reflex from the back wall dampened as much as you possibly can.


Edit: smelling pistake...


----------



## coolgeek




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9750#post_23741309
> 
> 
> A tri-corner is where three surfaces come together at a point. Two walls and either a ceiling or floor make a tri-corner. This defines what is also known as 1/8th-space.



Thanks. So, basically doing these would be ok then:


Behind the AT screen where I am putting my LCR and Sub.


1) I'll treat the ENTIRE space so that its a dead space (heard this from another thread. They say that the front wall needs to be dead.

2) put up 2 big bass traps, from floor to ceiling (about 4 inches deep?), or triangular on both tri-corners.

3) place my sub in the middle of the wall (dual corner loading).


Would that work?


----------



## bbm3

This is our first attempt to tame the acoustics in our little 12' wide X 16' long X 8' high echo chamber.


The idea was to make a hybrid panel that would attenuate some high frequency and also absorb some bass.


The frames are filled with 23" X 47" X 3" Roxul Safe and Sound.

We hit the first refection points on the side walls and will build 4 more for the ceiling and back wall.


I do not have any real empirical data to support my belief that this first phase has improved the room acoustics.

I can say that to my ears it is a good start and has made a positive difference.


Cost excluding labor = $26 per panel including shipping and tax.


*Layout and Cut the Frames:*
 

*Drill, Countersink, Glue, and Screw:*
 

*Wrap with Fabric:*


----------



## lbrown105

How effective are the tuned traps at rectifying bass ringing in a specific region. I have a 67hz ringing issue at most of my listening positions. My room is 33ft long and 14.5 ft wide except in front 8 ft of the room is about 17ft wide, so not a perfect rectangle. It also has a drop ceiling with insulation in between the joists.


I have seen some of these tuned traps which seem nice because that are not very deep but very expensive. do you have to cover specific corners or entire walls with them? Here are some graphs, disregard the 60hz tone comes from my measuring equipment but the 65-70hz range is real. I can tame it with PEQ but am more interested in solving it with treatment if possible.


----------



## HopefulFred




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9750#post_23768676
> 
> 
> do you have to cover specific corners or entire walls with them?


You need to know which surfaces are binding the standing wave (which walls does it reflect against). Then, if the trap is pressure based, place it where that standing wave is generating a pressure node.


You can walk around the room with the mic, playing pink noise, using REW's RTA feature. Look for areas where a trap would be feasible and the SPL for the offending frequency is high.


----------



## sdurani




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9750#post_23768676
> 
> 
> I have a *67*hz ringing issue at most of my listening positions. My room is 33ft long and 14.5 ft wide except in front 8 ft of the room is about *17*ft wide


The speed of sound divided by your room width should give you the frequency of your 2nd width mode.


1130 ÷ 17 = 66.5 (close enough to 67Hz)


Can you move your subwoofer to one of the quarter points of the 17ft room width (i.e., 4¼ feet from the side wall) and re-measure? Placing the sub in a null might help reduce the ringing.


----------



## Nightlord




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/9780#post_23768973
> 
> 
> Can you move your subwoofer to one of the quarter points of the 17ft room width (i.e., 4¼ feet from the side wall) and re-measure? Placing the sub in a null might help reduce the ringing.



Addendum: that's 4¼ feet from wall to center of the woofer cone, not 4¼ feet between wall and subwoofer cabinet - just to avoid any confusion.


----------



## lbrown105

Thanks I will give it a try this weekend


----------



## Digital_Chris

Couple questions for you guys. I heard that sandwiching 3-5mil plastic between OC703 will lower the absorption frequency, how dramatic would you say? I ask because I have 3 inches to work with for first reflection treatment so I could either use straight 3" or sandwich plastic between 2" and 1" pieces or even 3 pieces of 1". It will be a bit more expensive for all 1" but if it's a dramatic help, that's the way I will go. Thoughts?


Also, with no reflection panels in the room at all, the rear row of seating sounds much more open, less cluttered and just overall better than the front row, almost like I don't need first reflection panels for the 2nd row, how come the front row suffers more than the back row?


Room dimensions are 18' long by 10.5' wide and 7.5' tall. First row at about 10' and second around 14' from the screen.


----------



## RossoDiamante


I know the issue of risers as bass traps/broadband absorbers has been brought up a couple of times.  And the end of the discussion usually is that it is complicated and can have negative as well as positive influences on the acoustics of a room.

 

The conversation usually starts with whether cutting holes into a riser to allow the sound waves to interact with the fiberglass or other absorber that lies within the riser is beneficial.  And then it evolves into how many holes.  How big should the holes be.  Where should the holes be.  Etc.

 

I would like to phrase a related question from a slightly different perspective.  I can understand how cutting holes in the riser may help higher frequencies gain access to the absorbent material.  But for some reason, I have this impression in the back of my mind that says that lower frequencies (either because of their wavelength or amplitude?) are not easily "stopped" by ordinary construction materials like drywall, plywood, OSB, etc.  This explains in part why it is so hard to "soundproof" a home theater from the rest of the house and the supports the whole soundproofing industry of clips, channel, drywall, green glue, etc.

 

So my question is whether a riser, constructed of ordinary construction materials like 2x4's to 2x12's, 1/2-3/4" plywood or OSB, nails or screws, and maybe drywall or carpet or 3/8-5/8" wood flooring for example, would really pose an impediment to said low frequencies interacting with any absorbent materials within.

 

At the end of the day, is my 4'x18'x1.5' riser filled with fiberglass already acting as a bass trap of sorts even though there are no deliberate holes cut into it for acoustic considerations?  I have thought about cutting holes into it and seeing what would happen (and I may still do so anyways knowing that I can always just plug them up again before putting carpet down on the riser) but when I think more about it and the reports of the unpredictability of the net results, I've held off to date.  But when I actually measure my room, I have a prolonged decay time at 18-20 Hz. and also between 70-150 Hz.


----------



## NicksHitachi




> Quote:
> Originally Posted by *RossoDiamante*  /t/255432/acoustical-treatments-master-thread/9780#post_23883655
> 
> 
> I know the issue of risers as bass traps/broadband absorbers has been brought up a couple of times.  And the end of the discussion usually is that it is complicated and can have negative as well as positive influences on the acoustics of a room.
> 
> 
> The conversation usually starts with whether cutting holes into a riser to allow the sound waves to interact with the fiberglass or other absorber that lies within the riser is beneficial.  And then it evolves into how many holes.  How big should the holes be.  Where should the holes be.  Etc.
> 
> 
> I would like to phrase a related question from a slightly different perspective.  I can understand how cutting holes in the riser may help higher frequencies gain access to the absorbent material.  But for some reason, I have this impression in the back of my mind that says that lower frequencies (either because of their wavelength or amplitude?) are not easily "stopped" by ordinary construction materials like drywall, plywood, OSB, etc.  This explains in part why it is so hard to "soundproof" a home theater from the rest of the house and the supports the whole soundproofing industry of clips, channel, drywall, green glue, etc.
> 
> 
> So my question is whether a riser, constructed of ordinary construction materials like 2x4's to 2x12's, 1/2-3/4" plywood or OSB, nails or screws, and maybe drywall or carpet or 3/8-5/8" wood flooring for example, would really pose an impediment to said low frequencies interacting with any absorbent materials within.
> 
> 
> At the end of the day, is my 4'x18'x1.5' riser filled with fiberglass already acting as a bass trap of sorts even though there are no deliberate holes cut into it for acoustic considerations?  I have thought about cutting holes into it and seeing what would happen (and I may still do so anyways knowing that I can always just plug them up again before putting carpet down on the riser) but when I think more about it and the reports of the unpredictability of the net results, I've held off to date.  But when I actually measure my room, I have a prolonged decay time at 18-20 Hz. and also between 70-150 Hz.



Your riser could be operating as a panel resonator currently. It would depend on the resonant frequency of each cavity between the joists. The resonant freq was governed by the mass/density of the membrane(plywood) and the volume of the cavity.


You can google some BBC documents for info on panel resonators.


If you cut holes you then have a helmholtz resonator. I've played with calculators for Helmholtz and you have to take great care to tune the resonator to the center frequency of issue and even more difficult is getting an acceptably low Q which targets a wide enough band to be useful. Helmholtz typically have a very narrow frequency focus so hitting your target is very critical.


There are online calculators to play with which will give you an idea of what to expect. Basically your port will be the diameter of the hole and port length will be thickness of material you drill through.


----------



## HopefulFred




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/9780#post_23881785
> 
> 
> Couple questions for you guys. I heard that sandwiching 3-5mil plastic between OC703 will lower the absorption frequency, how dramatic would you say? I ask because I have 3 inches to work with for first reflection treatment so I could either use straight 3" or sandwich plastic between 2" and 1" pieces or even 3 pieces of 1". It will be a bit more expensive for all 1" but if it's a dramatic help, that's the way I will go. Thoughts?
> 
> 
> Also, with no reflection panels in the room at all, the rear row of seating sounds much more open, less cluttered and just overall better than the front row, almost like I don't need first reflection panels for the 2nd row, how come the front row suffers more than the back row?
> 
> 
> Room dimensions are 18' long by 10.5' wide and 7.5' tall. First row at about 10' and second around 14' from the screen.


Hey Chris - glad to see you back.


When I think about using plastic in absorbers I think of it sort like a ported subwoofer. The plastic should bump the performance up a little near the low end. The details are related to size and weight and being sealed, but I don't have an equation or anything. Given that the performance increase is based on resonant behavior, I would not think multiple layers would improve anything - but what do I know?


I have more speculation for you: the difference in sound between the two rows probably has to do with the time delay for the lateral reflections. The rear row will have a longer delay. That's one of the reasons that Toole does not prescribe absorption for those early lateral reflections: they often improve the overall sound quality.


----------



## Nightlord

As far as I have understood it, it doesn't actually increase bass dampening, it just shift the dampening towards more bass dampening by making the higher less dampened.


Please correct me if I'm wrong if anyone has real data on the contrary.


Doesn't mean it's a bad idea, it's much easier to overdampen the top.


----------



## Digital_Chris

Hey Fred! I finally got HVAC plumbed into the theater so I'm ready to finish it off with treatment.


Now, if the rear row sounds good as is, I'm worried that I'll ruin that openness by treating the front row. I'd like to improve the front row without affecting the rear, therefor, I will have to be very specific when placing reflection treatment for the front row, correct?


As far as sandwiching plastic, it might just end up being a huge hassle as to how it should be applied correctly but I might place strips/full sheets of plastic on top of the 703 to keep a little crispness in the room.


I also wonder how I should treat the front/rear wall. I feel that the rear wall will need absorption to kill rear wall reflections, correct?


----------



## HopefulFred

Nightlord, I'm not finding "real data" per se, but I think you will find this link useful, though the designs discussed there do work best with heavier membranes.



Chris, I think you should start with some ETC measurements for each row so we can see what you are preferring and what you're not liking, then we can figure out what needs to be done to make the front row as good as the rear - hopefully. Carefully placed absorption may be the best we can do, but some diffusion may be the right choice. I'm not sure I (personally) can tell based on ETC, but at least that will give you a starting point - and hopefully someone with some studio-design experience can help out.


The need for absorption on the rear wall will at least in part depend on the distance from the rear wall to the listeners. If it's close, the 1/4 wave cancellation might be strong enough to be a problem. Your second row is very close to the rear wall isn't it? Also, the timing of the reflection may be too close. If you find that you want a well-defined ITD, you will probably benefit from a kicker off the rear wall - I'm not sure what the process for that determination will look like, but ETC is the tool again. So we'll need some measurements (distances) and ETC for all the seating positions (or at least a representative sample). Also, you might just go ahead with absorption on the rear wall, because I know you still have bass issues (right?) - so some thick absorption may be the best choice for that reason, and then we can see about "livening" it back up with some plastic or diffusion on top.


----------



## Digital_Chris

Rear seats to back wall is about 4'. Not sure if you would call that "real close" but..


Yes, I do still have bass issues but not at the moment, subs are disabled. Basically, I was so sick of not having the real estate to apply proper low frequency treatments that I'd almost rather have no subs at all than a wacky sounding room :-/


Also, what is ITD and what is a "kicker"?


----------



## coolgeek




> Quote:
> Originally Posted by *Digital_Chris*  /t/255432/acoustical-treatments-master-thread/9780#post_23885671
> 
> 
> Rear seats to back wall is about 4'. Not sure if you would call that "real close" but..
> 
> 
> Yes, I do still have bass issues but not at the moment, subs are disabled. Basically, I was so sick of not having the real estate to apply proper low frequency treatments that I'd almost rather have no subs at all than a wacky sounding room :-/
> 
> 
> Also, what is ITD and what is a "kicker"?



I am going to have the exact same 'bass' issues with my relatively smallish basement (about 12 feet wide x 18 feet length from screen)... my back row would be about 2-3 feet from the wall boundary...


One solution i am thinking is to limit the low bass to 20hz... and not go below.. or something like that...


----------



## HopefulFred

ITD and kicker are terms usually applied to mixing and critical two-channel listening spaces, but they refer to psychoacoustic phenomena that relate to clarity and spaciousness in stereo imaging. When a reflection-free zone is established, such that no high-gain reflections are heard within the first 20 ms or so after the initial sound, you have an ITD - initial time delay or Haas interval. The ITD functions psychoacoustically to keep the perception of the direct sound undistorted. A kicker is a high-gain reflection that signals to the brain that the ITD has ended.


----------



## mtbdudex




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9780#post_23886885
> 
> 
> ITD and kicker are terms usually applied to mixing and critical two-channel listening spaces, but they refer to psychoacoustic phenomena that relate to clarity and spaciousness in stereo imaging. When a reflection-free zone is established, such that no high-gain reflections are heard within the first 20 ms or so after the initial sound, you have an ITD - initial time delay or Haas interval. The ITD functions psychoacoustically to keep the perception of the direct sound undistorted. A kicker is a high-gain reflection that signals to the brain that the ITD has ended.



Interesting, wiki says this about "kickers":
http://en.wikipedia.org/wiki/Precedence_effect 


> Quote:
> Haas kicker
> 
> 
> Many older LEDE ("live end, dead end") control room designs featured so-called "Haas kickers" - reflective panels placed at the rear to create specular reflections which were thought to provide a wider stereo listening area or raise intelligibility.[12] However, what is beneficial for one type of sound is detrimental to others, so Haas kickers just like compression ceilings are no longer commonly found in control rooms.[13]


----------



## HopefulFred

Interesting. Thanks for the link.


----------



## Holiday121

I have a question. I was thinking of building frames around my screen and using 4-8 inch thick Roxul safe and sound in them and wrapping them with black felt.


Do you think this could help at all?


----------



## yacht422

Question: I have a 16 X 22 X 10 purpose built H/T, with an entry opening in the center of one side wall. I have mounted two hollow construction cafe doors to serve as sound blockers, so to speak. My question is, would I experience better pressure from the subs(2)if I replaced the twin 18" wide hollow doors with one 36" solid wood door?


----------



## nickbuol

General statement when going to sound quality, solid door > hollow door. I am not even talking about any level of "soundproofing" here, but a hollow door would tend to flex more, and act like a drum (in a bad way). Plus two doors in a side-by-side setup would tend to rattle more than a single door.



Now, will you notice a difference in your particular room? Not sure. If there are other acoustical issues in the room, maybe not. If this is your weakest link and you are working on other acoustical properties, then maybe so. I just don't want you to think that just because it is "better" that you will actually notice a difference if, say, you have other rattles, or lots of peaks/nulls in the room, etc.


----------



## mtbdudex




> Quote:
> Originally Posted by *yacht422*  /t/255432/acoustical-treatments-master-thread/9780#post_23944802
> 
> Question: I have a 16 X 22 X 10 purpose built H/T, with an entry opening in the center of one side wall. I have mounted two hollow construction cafe doors to serve as sound blockers, so to speak. My question is, would I experience better pressure from the subs(2)if I replaced the twin 18" wide hollow doors with one 36" solid wood door?



With 2 doors you introduce more seal potential issues, any reason why you do not want to use just the 1 3ft wide door?



Sent from my iPad2 64GB using Tapatalk


----------



## yacht422

i felt it easier for our guests to enter through two swing doors rather than one big heavy wooden one.

but, i am considering moving to move bass capable subs( SVS, et al) and the idea of pressurization came to mind. ergo: the question i posed.

I really do not fully understand the room pressurization thing - - - not clear how much better the bass response will be with solid vs: swinging. (if at all - - - do not know how to measure(can one measure pressure??)


----------



## mtbdudex

Room pressurization has been talked here in depth, more so the audio forum or the DIY forum, search there for threads.

Acoustics thread is wrong for that, same sound isolation is not acoustics.


Actually I am in same boat as you, adding a double French door to my HT this winter, mine will be outside door, locking pins, extra sealed.


My concern for you is rattles if yours is not really solid.



Via my 64GB iPhone 5s using Tapatalk


----------



## nickbuol

Agreed, this acoustical treatments thread really only touches on how the door would effect the room itself, and thus the reason I only mentioned the hollow door maybe interacting with some frequencies in a more audible way, and put the disclaimer in my statement that everything else depends on room construction, sound isolation, etc.


While there is some overlap, yacht422 might get better responses elsewhere to sound pressurization questions.


----------



## wse

I need bass traps that look good are these any good?

http://www.vicoustic.com/hifi-home-cinema/products/acoustic-treatment/absorption/panel/473


----------



## mtbdudex




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9780#post_23950324
> 
> 
> I need bass traps that look good are these any good?
> 
> http://www.vicoustic.com/hifi-home-cinema/products/acoustic-treatment/absorption/panel/473



respectively, this is your HT, right?










I have to ask, do you exactly know what "issues" you have?


Rather than asking are these "good looking" panels any good? (I assume you mean "do they work")
 


I suggest:

You go back to your HT designer, show them where you feel ("hear") there are bass issues in your beautiful HT.

Then, have them show you fact based data on where your sound is acoustic measurement wise, and then they advise you their countermeasure to fix.

(I assume you had in the agreement certain specifications to meet, and if you HT is not meeting those they should "fix" that as part of contractual obligation)



Those wood panels, from their website:


> Quote:
> Optimized for corner mounting, Super Bass Extreme's elegant wooden front is based on Vicoustic's flagship Wave Wood panel. This is combined with a membrane, two high-density foam layers and a micro-perforated rear panel, with 1mm holes, that acts as a Helmholtz resonator. Designed to provide effective low frequency absorption between 60-125 Hz, it delivers maximum effectiveness between 75 -100Hz.


and graph;
 


Possibly they could help as part of a broader strategy "solve" you issues, depends......once your issues are clearly defined and understood


----------



## wse




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9780#post_23951179
> 
> 
> respectively, this is your HT, right?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have to ask, do you exactly know what "issues" you have?
> 
> 
> Rather than asking are these "good looking" panels any good? (I assume you mean "do they work")
> 
> 
> 
> I suggest:
> 
> You go back to your HT designer, show them where you feel ("hear") there are bass issues in your beautiful HT.
> 
> Then, have them show you fact based data on where your sound is acoustic measurement wise, and then they advise you their countermeasure to fix.
> 
> (I assume you had in the agreement certain specifications to meet, and if you HT is not meeting those they should "fix" that as part of contractual obligation)
> 
> 
> 
> Those wood panels, from their website:
> 
> and graph;
> 
> 
> 
> Possibly they could help as part of a broader strategy "solve" you issues, depends......once your issues are clearly defined and understood



I wish that was mine. I did my HT myself


----------



## mtbdudex




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9780#post_23951779
> 
> 
> 
> I wish that was mine. I did my HT myself



ok - I got that from your sig link, that picture was there










Have you gone the measurement route to objectively confirm what you subjective are hearing?


Post a pict of your HT, I'm curious what it does look like.


----------



## nickbuol

There are images in you link in your signature that show that room. I was confused too.


To me, the product is made of foam (generally not the best material) and stuffed inside a MDF box with a few slots "routed" out of the front.


Not sure of the price, but since you did your HT yourself, I wouldn't pay for that. With a little bit of time, some tools, and effort, you can make something that looks nice, but is cheaper and probably performs better.


I am generally skeptical of products that seem to focus on the looks of the product first, and then the performance is secondary.


----------



## wse




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9780#post_23951882 There are images in you link in your signature that show that room. I was confused too.
> 
> 
> To me, the product is made of foam (generally not the best material) and stuffed inside a MDF box with a few slots "routed" out of the front.
> 
> 
> Not sure of the price, but since you did your HT yourself, I wouldn't pay for that. With a little bit of time, some tools, and effort, you can make something that looks nice, but is cheaper and probably performs better.
> 
> 
> I am generally skeptical of products that seem to focus on the looks of the product first, and then the performance is secondary.


Yes, that was my worries as well!


----------



## wse


Here you are http://www.blu-ray.com/community/gallery.php?member=wes&folderid=3141


----------



## coolgeek

Would placing cork material around the entire walls be a good idea?


----------



## mtbdudex




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/9780#post_23959128
> 
> 
> Would placing cork material around the entire walls be a good idea?


What is the acoustic issue you are trying to address here?



Via my 64GB iPhone 5s using Tapatalk


----------



## mtbdudex




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9780#post_23958760
> 
> 
> Here you are http://www.blu-ray.com/community/gallery.php?member=wes&folderid=3141



Your room looks really nice.

Have you taken acoustic measurements?

If so, post them for understanding of what you are trying to accomplish per your earlier post.



Via my 64GB iPhone 5s using Tapatalk


----------



## coolgeek




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9810#post_23960110
> 
> 
> What is the acoustic issue you are trying to address here?
> 
> 
> 
> Via my 64GB iPhone 5s using Tapatalk



Right now it's basically a concrete bunker. Lots of echo. Someone told me to plaster cork all around as first phase of my treatment... not sure what cork does...


----------



## HopefulFred




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/9810#post_23960245
> 
> 
> not sure what cork does...


Not much. skip it. Measurements would help.


----------



## coolgeek




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9810#post_23960301
> 
> 
> Not much. skip it. Measurements would help.



Thanks.


----------



## nickbuol

You don't hear of people really using cork much (not saying that some people don't), but it is hard to fix things without accurate readings and testing. Of course, there are some things that can help using some general guidelines for all around acoustics. Check out these videos from AVS's content director Scott Wilkinson....


Acoustics 101








Acoustics 102


----------



## mtbdudex

I used cork for my DIY dartboard backing wall zone:
 


and my wifes craft room flooring
 


so it's nice to walk on, with the 3/4" thick underlayment, and good for stray darts.....


As acoustic treatment, well it will reflect the above Fs freq mostly, so won't help with any *specular reflection management* , and will do nothing for LFE bass management / modal ringing either.


HT Acoustics 101:

Why: Psychoacoustic studies, then application of those results have revealed that properly applied acoustic treatments can improve you subjective listening experience
 

What: Understand and manage the room/speaker/listener interaction to provide the "best" listening space

Where: first reflection points are good starters, and for bass / LFE modal ringing issues corners/wall intersections are good places also

How: depending on speakers/layout/room interaction and other factors, absorption and/or diffusion can be utilized

>>Key is attacking the issue, and not over absorbing if applying absorption, also absorbing across the spectrum - ie - not too thin or you will be applying an acoustic "filter" and color the sound


btw coolgeek, your build thread indicated that GIK and Bryan was hired already, so...... ????

Are you not liking their recommendations or what???
http://www.avsforum.com/t/1482805/coolgeeks-concrete-bunker-home-theater-build/60#post_23798198 


> Quote:
> Originally Posted by *coolgeek*  /t/1482805/coolgeeks-concrete-bunker-home-theater-build/60#post_23798198
> 
> 
> .......
> 
> 
> Right now, I have hired Bryan from GikAcoustics to help me design the treatments i'll need.
> 
> 
> I am thinking at least 6 months down the road...
> 
> 
> ...


----------



## Holiday121

I have a question was thinking of doing this besides corner bass traps.


In the picture below to the right and left of my screen are open wall space. Along the left and right side of the walls I built out panels Without insulation but more to absorb reflection.


Can I just put Roxul behind those panels and do the whole wall to the left and right of thee screen?


----------



## mtbdudex




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9810#post_23964808
> 
> 
> I have a question was thinking of doing this besides corner bass traps.
> 
> 
> In the picture below to the right and left of my screen are open wall space. Along the left and right side of the walls I built out panels Without insulation but more to absorb reflection.
> 
> 
> Can I just put Roxul behind those panels and do the whole wall to the left and right of thee screen?



Do you have *SBIR* issues and want to tackle them?


Putting absorption just anywhere should not be done, unless for a specific purpose based on some plan.


----------



## Holiday121

I have no clue honestly. I'm just going by some layouts people use mostly.


Is their anyway a complete noob can figure out where treatment is needed


----------



## mtbdudex




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9810#post_23965281
> 
> 
> I have no clue honestly. I'm just going by some layouts people use mostly.
> 
> 
> Is their anyway a complete noob can figure out where treatment is needed



sure - break up the sound into above the Fs and treat the first reflection areas for your front sound stage mains RCL.

Do that as minimal as possible, don't over absorb. The mirror trick works for that.
http://realtraps.com/rfz.htm 

It's best if you have a measurement mic to guide you, if not, then apply at least 2" of OC703 (or similar) + 2" air gap for your side wall panels.


If you apply just 1" of some acoustic material directly on side walls you will EQ your sound, not fully absorb it to the Fs.


More here:
http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-not-fixed-frames#post_19947420 


> Quote:
> Side note:
> 
> 
> I have this general suggestion for those wanting to learn about acoustics:
> 
> 
> 
> A) read this Acoustics/Treatment Reference Guide , via gearslutz, its a easy read in layman terms, starts you off with basics and good foundation with practical discussion. Studio acoustics and Home Theater acoustics.
> 
> 
> From that, simple/straight forward advice via Jens Eklund:
> 
> 
> 
> Quote:
> 1. Learn how to make measurements: REW - Room EQ Wizard Home Page
> 
> 
> Don’t do anything without measurements.
> 
> 
> 
> 2. Define your MLP (Master listening position). Confirm with measurements.
> 
> 
> (Mike R modified for HT viewpoint)
> 
> 
> 
> 3. Identify and treat your modal and SBIR - Speaker Boundary Interference Response related issues and educate yourself about different bass-absorbing techniques.
> 
> 
> Other info: SBIR by Bryan Pape
> 
> 
> 
> 4. Treat areas that otherwise creates early reflections.
> 
> 
> 
> 5. If the room is big enough, add diffusers (but read up on how to use diffusers before going nuts).
> 
> 
> 
> Always base your decisions regarding different treatment, on measurements. Avoid thin porous only absorbers (including wall to wall –carpet, drapes etc.) unless a measurement indicates the need for it.
> 
> 
> 
> 
> B) Knowing that for “best” audio/sound in a listening room, these parameters are tackled in prioritized order:
> 
> 
> 1. Speaker location, 2. Listener position, 3. Acoustic treatments, 4. Electronic correction.
> 
> 
> Understand the small room acoustic model you will follow.
> 
> 
> Looking at this link, everyone can see visually the various small room models, it's 7 pages from the book "Acoustics and Psychoacoustics Applied"
> http://eetimes.com/design/audio-desi...n?pageNumber=0
> 
> 
> 
> C) If you have desire for more knowledge:
> 
> 
> -read one of many books out there, a great 1st book is "Master Handbook of Acoustics" by F. Alton Everest, a perfect follow-up book is "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms" by Floyd Toole.
> 
> 
> -study Ethan Winers site, http://www.ethanwiner.com/acoustics.html
> 
> 
> -Become familiar with the different small room acoustic models for home listening spaces
> 
> 
> -This is also a 101 read on Room Acoustics, http://www.crutchfield.com/learn/learningcenter/home/speakers_roomacoustics.html
> 
> 
> -SAE Home Acoustics info site has many definitions and explanations http://www.sae.edu/reference_material/audio/pages/fullindex.htm
> 
> 
> -There are many other sites on the web, like
> 
> 
> ........One of the first ones, StudioTips small room acoustics forum http://forum.studiotips.com/index.php ,
> 
> 
> ........Acoustical measurements defined Rives audio http://www.positive-feedback.com/Issue12/rives2.htm ,
> 
> 
> ........RPG Acoustics Library papers http://www.rpginc.com/news/library.htm , etc.
> 
> 
> -Be careful of info overload all at once
> 
> 
> 
> D) Measurement info/threads:
> 
> 
> -online downloadable file with the Sound System Engineering chapter 6 on measurements http://www.focalpress.com/uploadedFiles/Books/Book_Media/Audio/9780240808307.pdf
> 
> -Get the hardware side of REW down quickly, this thread by member omegaslast dummy's guide on setting up REW and his blog http://polaraudio.blogspot.com/2012/01/calibration.html easy 101 read with pictures to walk you thru the mechanical of set-up and taking measurements
> 
> -Highly recommend Nyal Mellor's site, http://www.acousticfrontiers.com/Aco...surements.html , and a very detailed/helpful white paper http://blog.acousticfrontiers.com/st...ist.%20Rms.pdf
> 
> 
> - Room Measurement & Treatment by "fotto" (Floyd)
> 
> 
> - Envelope Time Curve - ETC - Impulse gearslutz thread
> 
> 
> - Using energy time curve for acoustic analysis: by "mtbdudex" (Mike R)
> 
> - http://www.avsforum.com/t/1421599/etc-isd-gap-question ETC - ISD gap by
> 
> 
> - Basic acoustic measurement primer v2.1 (via gearslutz "DanDan")
> 
> 
> - http://www.realtraps.com/art_measuring.htm
> 
> - http://www.avsforum.com/t/1316623/diy-custom-printed-movie-poster-acoustic-panels-cheap/60#post_20147783 DIY Custom-Printed Movie Poster Acoustic Panels
> 
> -first reflection software: http://www.avsforum.com/t/822273/free-software-to-help-determine-your-first-reflection-points/240#post_22619555
Click to expand...

[/QUOTE]


----------



## mrevo2u

Ok, I have read a lot of this thread but is there any issue with using acoustic foam panels (Sonex classic?) for front wall? I could add them over OC703, but I really like the 'recording studio/industrial' look of the foam panels (beats plain old GOM black for front wall/false wall)


----------



## richlo

I know that most fiberglass, rock wool come in standard size 4' x 2' panels and I see tons of picks where the new panel is stradling a corner, my question then is, is it necessary to have it 2' across or can 1' x 4' (lets assume 4" thick) work just as well? I rather have a smaller dimension in the room that is would be effective for bass as well as save where I can use the other piece to use on another corner?


Has anyone tested this?


----------



## SteveR1952




> Quote:
> Originally Posted by *mrevo2u*  /t/255432/acoustical-treatments-master-thread/9810#post_23980054
> 
> 
> Ok, I have read a lot of this thread but is there any issue with using acoustic foam panels (Sonex classic?) for front wall? I could add them over OC703, but I really like the 'recording studio/industrial' look of the foam panels (beats plain old GOM black for front wall/false wall)



I have just officially read the entire thread...not that I can remember all the details but some of it has stuck between my senile ears.


The issue with most foam products is lack of bass absorption. Foam comes in two basic flavors; open cell or closed cell. Closed cell will reflect more that it will absorb. Open cell will absorb more but from all that I have read here and elsewhere it still does not work as well as other products with more open internal material structures like random compressed glass fibers (fiberglass) or random compressed mineral fibers (Roxoul) or even cotton fibers. Open cell foam does not have the same structure on the microscopic level as does most fiber products. The tortuous pathway of compressed fibers creates a deeper passage from the surface of the panel for sound to enter and interact with the fibers to slow down the sound waves (absorb them) vs open cell foam which tends to have a very shallow and self-contained bubble-like structure which will absorb at the skin of the material but not so much further inside of it due to restrictions in the material itself.


I used to work the microscopic filtration so this stuff is very near and dear to my past vocation. Filtration of microorganisms is not that much different than sound waves in some respects. The fluid dynamics of water vs air is but one of the similarities.


Short answer: use a compressed fiber material; not open or closed cell foam for the best absorption.


----------



## BasementBob

Closed cell foam should not be considered for absorption (like concrete, it absorbs, just a tiny bit).


Open cell foam can be very effective. Make sure its tested and use its absorption coefficients as your guide.

Auralex sells lots of open cell foam wedges and things: http://www.auralex.com/testdata/ 


Wool (rockwool, fiberglass wool, and even cotton wool) is also very effective, with rockwool and fiberglass being the most effective for your $ because they are so inexpensive.

Some old comparisons at
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## matthewa

When building a riser is it better to seal it or could the three sides surrounded by the wall be left open and the cavity of the riser stuffed with pink fluffy to create a bass trap or is it better to be fully enclosed?


----------



## coolgeek




> Quote:
> Originally Posted by *matthewa*  /t/255432/acoustical-treatments-master-thread/9810#post_23996944
> 
> 
> When building a riser is it better to seal it or could the three sides surrounded by the wall be left open and the cavity of the riser stuffed with pink fluffy to create a bass trap or is it better to be fully enclosed?



I was going to ask the exact same question because I don't really have much space for Bass Traps.. .


----------



## Skylinestar

I am planning to build a thick bass trap and wrap it with black velvet (absorb reflected ambient light). Can the bass energy (sub 150Hz) goes through the velvet?


----------



## mrevo2u

My theater is basically a concrete box (slab floor) with a raised floor above part of it to create a two tier riser (floor is standard residential construction with engineered joists, 1 1/8" subfloor, glued and screwed). Should area below 'riser' be filled with pink insulation (volume is over 1000 cubic feet)?


----------



## HopefulFred




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9810#post_24043671
> 
> 
> I am planning to build a thick bass trap and wrap it with black velvet (absorb reflected ambient light). Can the bass energy (sub 150Hz) goes through the velvet?


While some materials may be slightly more transparent to low frequency sound, I think you will find the difference is virtually immeasurable for this purpose. Proceed with confidence, says I.



> Quote:
> Originally Posted by *mrevo2u*  /t/255432/acoustical-treatments-master-thread/9810#post_24044670
> 
> 
> My theater is basically a concrete box (slab floor) with a raised floor above part of it to create a two tier riser (floor is standard residential construction with engineered joists, 1 1/8" subfloor, glued and screwed). Should area below 'riser' be filled with pink insulation (volume is over 1000 cubic feet)?


Any enclosed air cavity has the potential to resonate and color the sound of the space. Loosely fill with insulation - the cheaper the better.


----------



## Holiday121

I went to joan fabrics today and they had speaker fabric. I was going to build me some diamond shape side panels but the fabric kinda was see through. It was black and actually called speaker fabric.


Anyone else recommend any other kind because you would be able

To clearly see through it


----------



## mtbdudex




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9810#post_24046446
> 
> 
> I went to joan fabrics today and they had speaker fabric. I was going to build me some diamond shape side panels but the fabric kinda was see through. It was black and actually called speaker fabric.
> 
> 
> Anyone else recommend any other kind because you would be able
> 
> To clearly see through it



I used that exact same speaker grille fabric and not an issue
http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-moveable-corner-traps-not-fixed-frames#post_19947600 


> Quote:
> Originally Posted by *mtbdudex*  /t/1312693/diy-construction-methods...e-corner-traps-not-fixed-frames#post_19947600
> 
> 
> Wrapping fiberglass 101, it's itchy be careful!
> 
> 
> 
> Cut to size, my speaker grille fabric came from Joanns, 60" wide, I bought 15 yards, $8/yard with coupon normal $9.99/yard.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> wrap a side and pin with 1 3/4" pins, angles to stay in from tension.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Complete the wrap, it's my first time, got decent at wrapping and pinning.
> 
> 
> Went real quick w/o mess.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Frontside mounted.............Backside mounted (after stained the frame)
> 
> 
> 
> 
> 
> 
> 
> .


----------



## Pain Infliction




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24046606
> 
> 
> I used that exact same speaker grille fabric and not an issue
> http://www.avsforum.com/t/1312693/diy-construction-methods-of-hang-able-acoustic-panels-moveable-corner-traps-not-fixed-frames#post_19947600



Mike, I love your cloud acoustic panels!


----------



## Nighthawk26

So I've tried this question in various ways in a few other sections but to no avail.


Martin Logan ESL or Theos electrostats behind a very fine AT screen. About 2.5 feet from side and just over 2 ft from back wall. Used mostly as a dedicated theater but with some stereo as well. Due tot he Electrostats being a dipolar speaker and having the front wall treated, what might I expect, and are there any ways to make adjustments to make it work. I will have an audessey multiEQX32 mic to use for setup if that mkes a difference.


Any feedback would be amazing at this point.


Edit.


This is whats on ML's website... towards the end it perhaps could suggest maybe depth of soundstage would be the only posisble compromise? To what degree?


Another key attribute of the ElectroMotion ESL is its naturally dipolar radiation pattern. A true dipole, The EM-ESL radiates sound with equal intensity from the front and back of its diaphragm, but the outputs are in opposite phase. As a result, sound waves rippling out toward the sides meet at the speaker's edge and cancel. That and the relatively large size of the ElectroMotion ESL's electrostatic panel cause output at the sides to be very low relative to that of a conventional loudspeaker, which in turn minimizes side-wall reflections that tend to muddle sonic detail and stereo imaging. While the reduction in output to the sides contributes to the astonishing clarity for which electrostats are revered, the energy reflected off the wall behind the speaker opens up and deepens the sound.


----------



## mrevo2u

Nighthawk - I am not an expert, but do love ML speakers (still have Prodigy's). I believe the purpose of setting them away frommthe wall is to keep the sound from rear of panel from reflecting off wall and creating a null. Spaced away from the wall diffuses the sound avoiding the null. Your acoustic treatment will absorb the rear wave, turning the ML into more of a direct radiating speaker. That's my understanding of it at least. You might want to research the outrageous theater done by the president of ML for his personal house.


----------



## Nighthawk26

Thanks mrevo2u... thats about as much as I've come to "understand". I use the term very varefully. What I don't know is how this translates into performance. Is it just not "idea;", will it be horrible, etc. I've called ML a few times as each time I have a different experience, and they all said it would be fine. At one point I got a guy who was snobby enough that when I questioned him, he went on to tell me his longstanding tenure at ML. I've posted in the ML thread, the dedicated HT thread, and now this one. Lots of views, yet no comments, which makes me feel like most simply don't know. We can all repeat the theory, but I need a little more.


----------



## cgott42

I'm about to start (re)building my HT - and when I'm done will apply acoustic treatments - so I haven't read this thread yet

But wanted to ask now - Being that my walls will be 2-3 layers thick of DW+GG before I apply acoustic treatment - How do I attach the acoustic treatments to the walls - are they screwed in directly to the wall- or will there be additional thickness that I'm going to need to screw through (and should have a layer of OSB board in my wall)?


also - for when I do start the treatment - to save me from reading 328 pages of posts - is there a summary with the current consensus(es)?


----------



## Hades84

I DIY'd a couple of panels for my lounge room. They're on my thread here:

http://www.avsforum.com/t/1454364/haydens-ht#post_23698831


----------



## Nightlord




> Quote:
> Originally Posted by *cgott42*  /t/255432/acoustical-treatments-master-thread/9810#post_24110041
> 
> 
> I'm about to start (re)building my HT - and when I'm done will apply acoustic treatments - so I haven't read this thread yet
> 
> But wanted to ask now - Being that my walls will be 2-3 layers thick of DW+GG before I apply acoustic treatment - How do I attach the acoustic treatments to the walls - are they screwed in directly to the wall- or will there be additional thickness that I'm going to need to screw through (and should have a layer of OSB board in my wall)?
> 
> 
> also - for when I do start the treatment - to save me from reading 328 pages of posts - is there a summary with the current consensus(es)?



It would have to be severely heavy treatments if screwing into double layers dw won't hold it... Mine are quite light, I just stapled them to the dw.


----------



## cgott42

Thx


----------



## artur9

What are my options for dealing with this room mode @ 30Hz? I mean, besides like 5' of pink fluffy on all the walls.


I imagine all the options are expensive







so I probably won't address it anytime soon.


----------



## Roger Dressler




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9840#post_24122063
> 
> 
> What are my options for dealing with this room mode @ 30Hz? I mean, besides like 5' of pink fluffy on all the walls.


One band of PEQ. Really.


----------



## Nightlord

Agree with PEQ as the easiest choice, other alternative if you have space to waste could be a tuned helmholtz. That would keep the initial wavefront intact, which the PEQ won't.


----------



## Roger Dressler

^^ He needs 10 dB attenuation at 30 Hz. An absorber (even lots of them) won't get him there. A second, well-placed sub might help, but the cheapest solution is the PEQ.


----------



## Nightlord




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9840#post_24126999
> 
> 
> ^^ He needs 10 dB attenuation at 30 Hz. An absorber (even lots of them) won't get him there. A second, well-placed sub might help, but the cheapest solution is the PEQ.



What do you base that on? 3-4dB reduction may be enough to satisfy all but measurement-curve-viewing, while peq to flat curve may do quite harmful things to the impulse behavior. Satisfying measurement mics and satisfying the ear is far from the same thing. If reality and the map is not in agreement, you don't navigate by map, do you?


----------



## Roger Dressler




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9840#post_24132333
> 
> 
> What do you base that on?


Just personal experience, starting with the RABOS PEQ technique with Infinity and Aerial subs many moons ago, which is not only simple to do but dramatically effective in addressing "one note" bass as exhibited in Artur9's plot. I don't know anything simpler or more cost-effective (after moving the sub around the room) than to try PEQ and verify by listening and measurements. Do you?


For those seeking further details, I would suggest reading part 2.2.4 of *Tool's paper* .

.


----------



## artur9




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9840#post_24132861
> 
> 
> (after moving the sub around the room)



I have done that. Unfortunately, I have not had luck in addressing that mode. I think it's a combination of my subwoofer not going that low (it's an Outlaw Audio M8 spec'ed to go down to 29Hz) and that the mode seeming lines diagonal across the room. See this post 


Now to find a suitable electronic device.... Suggestions? The equalizers I've seen online don't seem to go that low.


----------



## Roger Dressler




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9840#post_24133283
> 
> 
> I think it's a combination of my subwoofer not going that low (it's an Outlaw Audio M8 spec'ed to go down to 29Hz)


It would not help the resonance problem to have a sub that goes deeper.


> Quote:
> Now to find a suitable electronic device.... Suggestions? The equalizers I've seen online don't seem to go that low.


Have you looked at MiniDSP?


----------



## artur9




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9840#post_24133686
> 
> 
> It would not help the resonance problem to have a sub that goes deeper.



I thought one of the possibilities was to use multiple subwoofers to cancel out modes?


> Quote:
> Have you looked at MiniDSP?



I've looked into it a bit. I've subscribed to the minidsp forum here and intend to spend the next few weeks reading through it. I did the same for this thread (wow! 10 years of postings).


Learning curve seems painful







and I'm not sure how it would affect the quality of my system. I do notice the effect that using my prepro to digitize and bass manage my music has. That is, I can hear a difference between bypass and non-bypass. (Not claiming any ability to do so under lab conditions







). It's the redigitization I am most concerned about as I hear no difference if I keep everything digital as long as I can.


----------



## Roger Dressler




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9840#post_24134312
> 
> 
> Learning curve seems painful


There are other solutions, and lots of help around here no matter what route you take.


> Quote:
> and I'm not sure how it would affect the quality of my system. I do notice the effect that using my prepro to digitize and bass manage my music has. That is, I can hear a difference between bypass and non-bypass. (Not claiming any ability to do so under lab conditions
> 
> 
> 
> 
> 
> 
> 
> ). It's the redigitization I am most concerned about as I hear no difference if I keep everything digital as long as I can.


The PEQ unit would only be present in the subwoofer signal path, so it will not degrade the rest of the signals, and such digital side effects will not be audible from the subwoofer.


----------



## mazdacub

Thought i would post up some of my easy panel builds. We just moved into a new house so now i have a designated area for the theater. It has hardwood floors and is such a live room. Did up a little plan to get the ball rolling and then started to make the panels. So far the front and right walls are treated with absorbing panels and a single diffuser was just added to the right wall for a test panel. to see if i like using the same fabric for all the panels.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/TestIdea2.jpg.html  


The acoustic panels were framed with 3/4" x 1 1/2" mdf boards cut to get a finished panel size of 24" x 48".

http://s96.photobucket.com/user/maz...12fc22bc-6483-4210-9b05-cf5830ba8257.jpg.html  


Basic 90 deg brackets were added to hold the corners together.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1165.jpg.html  


Roxul Insulation was used to fill the panel. Little trimming was needed to fit in the frames.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1169.jpg.html  


You get a perfect flush fit.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1170.jpg.html  


Cheap backing fabric was then fastened to the back side followed by the finished fabric to the front side.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1171.jpg.html  

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1173.jpg.html  


2 panels were constructed the same size for the ceiling are over the listening position. Only thing i did differently was added 2 wood dowels across the panels after grooving out the insulation. This will stop the insulation for sagging and stretching the fabric.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1177.jpg.html  


I constructed one diffuser panel as a test today also. I used 3/4" x 3" mdf this time around to give me more panel depth. For the core i used 1" thick rigid insulation.


First i made a frame that was 18" x 48" overall in size. Then i cut the rigid insulation into 1 1/2" and 3" strips.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1179.jpg.html  


What i did was basic and nothing fancy but have a feeling having 1" between all the layers is being a bit on the tight side. I simply alternated going from no insulation to the 1 1/2" bit and then to the 3" bit. Every change in chunk depth i left a 1" gap to use the wall as the reflective surface.

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1182.jpg.html  

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1181.jpg.html  


The difference at the moment is outstanding compared to having the walls all open.


Here is a horrible phone picture showing the progress and tht one test diffuser panel installed between the first 2 acoustic panels. Another diffuser will soon follow between the 3rd and 4th panel.


Any suggestions or comments i can incorporate into the design to help it out?

http://s96.photobucket.com/user/mazdacub/media/HT Setup/IMG_1186.jpg.html


----------



## Nightlord




> Quote:
> Originally Posted by *Roger Dressler*  /t/255432/acoustical-treatments-master-thread/9840#post_24132861
> 
> 
> I don't know anything simpler or more cost-effective (after moving the sub around the room) than to try PEQ and verify by listening and measurements. Do you?



Simpler, possibly - depends on what one thinks is simple. Cost-effective... probably not. Something someone wants to do? Definitely not, not even I want to do it, so I won't waste thread space describing it.


----------



## granroth

This post was inappropriate for the Acoustical treatments master thread, and so it has been moved to here: Soundproofing Master Thread - Post 24157444


----------



## mtbdudex

Congrats on tackling acoustics.

I suggest you read and apply info from this site for your diffuser, there is science behind building them, yours will not function to your intended purpose.

How they work 101: http://www.subwoofer-builder.com/qrd.htm 


Calculator to design them: http://www.subwoofer-builder.com/qrdude.htm 
 


> Quote:
> Originally Posted by *mazdacub*  /t/255432/acoustical-treatments-master-thread/9840#post_24134682
> 
> 
> Thought i would post up some of my easy panel builds. We just moved into a new house so now i have a designated area for the theater. It has hardwood floors and is such a live room. Did up a little plan to get the ball rolling and then started to make the panels. So far the front and right walls are treated with absorbing panels and a single diffuser was just added to the right wall for a test panel. to see if i like using the same fabric for all the panels.
> 
> 
> 
> I constructed one diffuser panel as a test today also. I used 3/4" x 3" mdf this time around to give me more panel depth. For the core i used 1" thick rigid insulation.
> 
> 
> First i made a frame that was 18" x 48" overall in size. Then i cut the rigid insulation into 1 1/2" and 3" strips.
> 
> 
> 
> What i did was basic and nothing fancy but have a feeling having 1" between all the layers is being a bit on the tight side. I simply alternated going from no insulation to the 1 1/2" bit and then to the 3" bit. Every change in chunk depth i left a 1" gap to use the wall as the reflective surface.
> 
> 
> 
> 
> 
> The difference at the moment is outstanding compared to having the walls all open.
> 
> 
> Here is a horrible phone picture showing the progress and tht one test diffuser panel installed between the first 2 acoustic panels. Another diffuser will soon follow between the 3rd and 4th panel.
> 
> 
> Any suggestions or comments i can incorporate into the design to help it out?


----------



## mtbdudex

Granroth;

You realize there is a difference between acoustics and soundproofing?


Your soundproofing inquiry would get better response in its own thread.



Via my iPhone 5s using Tapatalk


----------



## granroth




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24142662
> 
> 
> Granroth;
> 
> You realize there is a difference between acoustics and soundproofing?
> 
> 
> Your soundproofing inquiry would get better response in its own thread.



Yes, I do realize there is a difference... but perhaps I thought the difference was smaller and more subtle than it is? I posted here on the assumption that the same people who are experts on acoustic control could also be experts on sound leakage. If those domains aren't overlapping, then I agree that this is the wrong place for such a question.


To be bluntly honest, I also posted here rather than starting a new thread on the hope that my question would attract the attention of more experts. I have had minimal luck getting solid advice on some of the questions I've asked in earlier new threads. I don't know if it's because my questions are too esoteric for there to be an answer to, or if my newbie stature in AVS Forum just causes the necessary experts to pass on by. My thinking is that if I post a sound related question to a master thread filled with sound experts, that the latter case would be nullified and it would only be the singular uniqueness of the question that could prove problematic.


If you do think that my question is wholly inappropriate for this thread, then I'll certainly move it.


----------



## lbrown105




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9840#post_24142662
> 
> 
> Granroth;
> 
> You realize there is a difference between acoustics and soundproofing?
> 
> 
> Your soundproofing inquiry would get better response in its own thread.
> 
> 
> 
> Via my iPhone 5s using Tapatalk


please explain this. My understanding was soundproofing was a specific subject matter within the field of acoustics.


----------



## nickbuol




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9840#post_24145183
> 
> 
> please explain this. My understanding was soundproofing was a specific subject matter within the field of acoustics.



Yes and no. This thread is more for the treatment of the acoustical properties within the room. Soundproofing is the separation and isolation of sound inside the room (treated or not) and the surrounding living space.


Both are distinctly different enough to justify their own separate threads.


However, yes, no soundproofing or poor soundproofing means more sounds coming in to the room and impacting the sound quality inside the room (although most people do soundproofing to keep the sound in the theater from going throughout the rest of the house.


----------



## lbrown105

I have a question I think may be appropriate for this thread. I tried a new thread in the dedicated theater construction forum but nothing so far and may fit better here. Any guidance is appreciated. I currently have a 33x14x7.5 ft room with all drywall walls with insulation. The ceiling is a drop ceiling with R19 insulation above it. I am considering DD+GG and whisper clips/channel for the ceiling. I want to do this for aesthetic and sound control reasons but also want to get a best guess on how it may affect acoustic performance in the room. In particular I am interested how it will affect the bass region from say 20-500hz. Adding 2" absorber panels to the new ceiling would not be a problem for treating first reflections. I will probably gain about 3" on the ceiling based on joist height and my calcs for the whisper clips and DD. Right now I have what I consider pretty decent bass decay down to about 50hz and I suspect the entire ceiling is helping bass trap to a certain extent. I do not know exactly how much because I have never measured the room without the ceiling in this configuration. I am curious to hear opinions about this ceiling change and how it would likely affect the bass region. I guess one of my concerns is that that although the new ceiling may lower the resonance point of the room, it may do so like a tuned bass trap and only help in a very specific region vs what I have now which is more broadband. I really don't have a lot of room to add deep sofits around the perimeter of the ceiling to act as bass traps. I am hoping the DD+GG on whisper clips will not reduce the current sound quality I have in the room.


Here is a shot of the drop ceiling (black tiles are just acoustically transparent cloth to reduce first reflections by allowing the R19 to absorb high feq's. Also a shot of the bass region at the mlp. Any guidance is appreciated.


----------



## granroth




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24145572
> 
> 
> Both are distinctly different enough to justify their own separate threads.



Well, I was just off-the-charts presumptuous and created a Soundproofing Master Thread to cover such questions. Hopefully that was not stepping over too many lines. If calling it a "master thread" is too much, then I won't mind if the mods just rename an existing thread and make it sticky. Something like the Need help with soundproofing my new HT thread, for instance.


----------



## mtbdudex




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/9840#post_24147907
> 
> 
> 
> 
> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24145572
> 
> 
> Both are distinctly different enough to justify their own separate threads.
> 
> 
> 
> 
> Well, I was just off-the-charts presumptuous and created a Soundproofing Master Thread to cover such questions. Hopefully that was not stepping over too many lines. If calling it a "master thread" is too much, then I won't mind if the mods just rename an existing thread and make it sticky. Something like the Need help with soundproofing my new HT thread, for instance.
Click to expand...


I think what you did is fine, there are many separate threads that could be added to yours.

I suggest you do a reserve on the first 2-3 posts to organize it with links to other soundproofing threads, or once it gets going to key discussion points.


----------



## coolgeek

Would something like this be good for acoustics? I am thinking of plastering these or rockwool behind the stage

http://www.alibaba.com/product-gs/1452942194/Excellent_sound_absorbing_performance_Acoustic_panel.html


----------



## nickbuol




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/9840#post_24147907
> 
> 
> Well, I was just off-the-charts presumptuous and created a Soundproofing Master Thread to cover such questions. Hopefully that was not stepping over too many lines. If calling it a "master thread" is too much, then I won't mind if the mods just rename an existing thread and make it sticky. Something like the Need help with soundproofing my new HT thread, for instance.



Not sure if there was some sarcastic tone directed at me, but I think that what you did is perfectly fine and probably should have been done some time ago. Thank you.


> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/9840#post_24149272
> 
> 
> Would something like this be good for acoustics? I am thinking of plastering these or rockwool behind the stage
> 
> http://www.alibaba.com/product-gs/1452942194/Excellent_sound_absorbing_performance_Acoustic_panel.html



Foam - shudder.....

Thin Convoluted Foam - puke....


OK. In all seriousness, you need to know what is "wrong" with your room to properly know what you need to fix. If you are only fighting issues that could be fixed with what the foam would absorb, then 1) you would be super lucky, 2) your tests are probably lying to you. LOL


Now, back with my very first HT I did in 1996, which was back before information was more readily available on what works and doesn't, etc, I literally used contact cement, rolled it on to my theater walls, and put thick, black felt on the walls, sort of like wallpaper, and it made a BIG difference in the sound of the room. Did it seem to fix some things like echo and ringing in the room? Yes. Was it a good fix? Heck no. I was ignoring 95% (I am making that number up) of the frequencies in the room. Those foam panels would be probably better than the felt that I used, but again, only for a limited frequency range. Even with the thickest 50mm (1.97inch) panel, you are still only getting high frequecies (they even state that in their listing). Plus that is at $10 per sq meter and you need to order a minimum of 1000 sq meters to get that price. That means that elsewhere will probably be higher than that due to a lower quantity needed.


I would stay away from the foam as a "general rule." (There are always exceptions.) Rockwool would suite your better and isn't badly priced.


----------



## toofast68




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9840#post_24147732
> 
> 
> I have a question I think may be appropriate for this thread. I tried a new thread in the dedicated theater construction forum but nothing so far and may fit better here. Any guidance is appreciated. I currently have a 33x14x7.5 ft room with all drywall walls with insulation. The ceiling is a drop ceiling with R19 insulation above it. I am considering DD+GG and whisper clips/channel for the ceiling. I want to do this for aesthetic and sound control reasons but also want to get a best guess on how it may affect acoustic performance in the room. In particular I am interested how it will affect the bass region from say 20-500hz. Adding 2" absorber panels to the new ceiling would not be a problem for treating first reflections. I will probably gain about 3" on the ceiling based on joist height and my calcs for the whisper clips and DD. Right now I have what I consider pretty decent bass decay down to about 50hz and I suspect the entire ceiling is helping bass trap to a certain extent. I do not know exactly how much because I have never measured the room without the ceiling in this configuration. I am curious to hear opinions about this ceiling change and how it would likely affect the bass region. I guess one of my concerns is that that although the new ceiling may lower the resonance point of the room, it may do so like a tuned bass trap and only help in a very specific region vs what I have now which is more broadband. I really don't have a lot of room to add deep sofits around the perimeter of the ceiling to act as bass traps. I am hoping the DD+GG on whisper clips will not reduce the current sound quality I have in the room.
> 
> 
> Here is a shot of the drop ceiling (black tiles are just acoustically transparent cloth to reduce first reflections by allowing the R19 to absorb high feq's. Also a shot of the bass region at the mlp. Any guidance is appreciated.


 

LB - so I am not sure exactly how to help you out, other than note my waterfall looks a lot like yours...except I have no ceiling treatment at all yet.

 

I have a wacky room, but my front wall is fully treated and I have 2 floor to ceiling corner bass traps.


----------



## granroth




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24150181
> 
> 
> Not sure if there was some sarcastic tone directed at me, but I think that what you did is perfectly fine and probably should have been done some time ago. Thank you.



Not sarcastic at all! I'm new to AVS Forum, but have extensive experience with other forums going back to the early 90s. I understand that newbies often have to "prove their mettle" before regulars will accept certain types of input.


When I have 500 posts under my belt, _then_ I may start getting sarcastic every now and then


----------



## wse




> Quote:
> Originally Posted by *mazdacub*  /t/255432/acoustical-treatments-master-thread/9840#post_24134682
> 
> 
> Thought i would post up some of my easy panel builds. We just moved into a new house so now i have a designated area for the theater. It has hardwood floors and is such a live room. Did up a little plan to get the ball rolling and then started to make the panels. So far the front and right walls are treated with absorbing panels and a single diffuser was just added to the right wall for a test panel. to see if i like using the same fabric for all the panels.
> 
> 
> 
> 
> The acoustic panels were framed with 3/4" x 1 1/2" mdf boards cut to get a finished panel size of 24" x 48".
> 
> 
> 
> 
> Basic 90 deg brackets were added to hold the corners together.
> 
> 
> 
> 
> Roxul Insulation was used to fill the panel. Little trimming was needed to fit in the frames.
> 
> 
> 
> 
> You get a perfect flush fit.
> 
> 
> 
> 
> Cheap backing fabric was then fastened to the back side followed by the finished fabric to the front side.
> 
> 
> 
> 
> 
> 
> 2 panels were constructed the same size for the ceiling are over the listening position. Only thing i did differently was added 2 wood dowels across the panels after grooving out the insulation. This will stop the insulation for sagging and stretching the fabric.
> 
> 
> 
> 
> I constructed one diffuser panel as a test today also. I used 3/4" x 3" mdf this time around to give me more panel depth. For the core i used 1" thick rigid insulation.
> 
> 
> First i made a frame that was 18" x 48" overall in size. Then i cut the rigid insulation into 1 1/2" and 3" strips.
> 
> 
> 
> 
> What i did was basic and nothing fancy but have a feeling having 1" between all the layers is being a bit on the tight side. I simply alternated going from no insulation to the 1 1/2" bit and then to the 3" bit. Every change in chunk depth i left a 1" gap to use the wall as the reflective surface.
> 
> 
> 
> 
> 
> 
> The difference at the moment is outstanding compared to having the walls all open.
> 
> 
> Here is a horrible phone picture showing the progress and tht one test diffuser panel installed between the first 2 acoustic panels. Another diffuser will soon follow between the 3rd and 4th panel.
> 
> 
> Any suggestions or comments i can incorporate into the design to help it out?


Very nice great step by step pictures


----------



## coolgeek




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9840#post_24150181
> 
> 
> Not sure if there was some sarcastic tone directed at me, but I think that what you did is perfectly fine and probably should have been done some time ago. Thank you.
> 
> Foam - shudder.....
> 
> Thin Convoluted Foam - puke....
> 
> 
> OK. In all seriousness, you need to know what is "wrong" with your room to properly know what you need to fix. If you are only fighting issues that could be fixed with what the foam would absorb, then 1) you would be super lucky, 2) your tests are probably lying to you. LOL
> 
> 
> Now, back with my very first HT I did in 1996, which was back before information was more readily available on what works and doesn't, etc, I literally used contact cement, rolled it on to my theater walls, and put thick, black felt on the walls, sort of like wallpaper, and it made a BIG difference in the sound of the room. Did it seem to fix some things like echo and ringing in the room? Yes. Was it a good fix? Heck no. I was ignoring 95% (I am making that number up) of the frequencies in the room. Those foam panels would be probably better than the felt that I used, but again, only for a limited frequency range. Even with the thickest 50mm (1.97inch) panel, you are still only getting high frequecies (they even state that in their listing). Plus that is at $10 per sq meter and you need to order a minimum of 1000 sq meters to get that price. That means that elsewhere will probably be higher than that due to a lower quantity needed.
> 
> 
> I would stay away from the foam as a "general rule." (There are always exceptions.) Rockwool would suite your better and isn't badly priced.



Thanks,... will stick to rockwool then... Sometimes I see something new and thought it might work better than rockwool...


----------



## lbrown105




> Quote:
> Originally Posted by *toofast68*  /t/255432/acoustical-treatments-master-thread/9840#post_24150227
> 
> 
> LB - so I am not sure exactly how to help you out, other than note my waterfall looks a lot like yours...except I have no ceiling treatment at all yet.
> 
> 
> I have a wacky room, but my front wall is fully treated and I have 2 floor to ceiling corner bass traps.



thanks for sharing the waterfall plot. Can you describe your ceiling type?


I should probably forge ahead and get the ceiling done the way I want and then deal with trapping if necessary. I am hoping someone out there went through the same progression and has before and after FR and waterfall plots. If not, I will certainly post my results later this spring when I am finished with the ceiling. With as many people doing DD+GG on clips and channel I am surprised I have not come across someone yet with some opinion on this type of ceiling change.


----------



## toofast68




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9840#post_24152617
> 
> 
> 
> thanks for sharing the waterfall plot. Can you describe your ceiling type?
> 
> 
> I should probably forge ahead and get the ceiling done the way I want and then deal with trapping if necessary. I am hoping someone out there went through the same progression and has before and after FR and waterfall plots. If not, I will certainly post my results later this spring when I am finished with the ceiling. With as many people doing DD+GG on clips and channel I am surprised I have not come across someone yet with some opinion on this type of ceiling change.


 

So I have a "raised" ceiling...in front of the main listening area.  Meaning in front of the MLP I have soffits all the way, and the ceiling is raised about 18", then right over the seats the ceiling drops back down to about 7 1/2 feet, or close to that.

 

Ok, this drawing is after too much coffee this am, digging out of a foot of snow, but you get the idea.  I think the first reflections in my room are bouncing off the front ceiling wall and then stopping at the front wall as it is 100% deadened.  Just my guy though, have no idea for sure.


----------



## BasementBob




> Quote:
> Originally Posted by *mazdacub*  /t/255432/acoustical-treatments-master-thread/9840#post_24134682
> 
> 
> I constructed one diffuser panel as a test today



If you ever do that again, use differing sizes between the vertical spots -- i.e. change your well width randomly.


----------



## BasementBob




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/9840#post_24139733
> 
> 
> I am trying to find an answer to an apparently esoteric acoustic question: does inserting insulation in between the walls in a double wall scenario either a) hurt the soundproofing b) increase the soundproofing or c) do nothing one way or another?



Insulation in the walls helps soundproofing.

Amongst other things, it dampens the resonance of the wall leafs.


If you're building walls, ceilings, around a home theatre, the rule of thumb is: insulation in the cavity is REQUIRED.


I don't regard Owens Corning as an expert in this area.

NRC is an expert. Very much an expert.


The stuff published by Brian at soundproofingcompany.com (aka Green Glue) is also really really good -- especially for us since it's mostly done from a home theatre point of view. Some of it gets dumbed down by the web guys there though, which isn't optimal.


This line by the NRC is correct,


> Quote:
> •partially filling the cavity from bottom to top, or from sides toward the middle, is less effective than having the same amount of material completely covering the whole inner face of the cavity.


but you've interpreted it incorrectly.

You're thinking of batts of fiberglass pink, or rigid Rockwool.

Consider what happens with blown in cellulose insulation in a wall cavity.


They're not talking about coupling the entirety of the leaves to each other by insulation as you drew.


What they mean is any of these are good:































but this is bad











Similarly batts that fall off one wall, or shrink with time, or blown in cellulose insulation, all break the rule:

The sound must go through insulation to be damped.

If there's a path around the insulation, (over it as would be the case with cellulose, or around it as shown in the above diagram), that's bad.





Note that Brian of soundproofingcompany.com did some tests and was surprised to find that











worked remarkably well, from a bang-for-the-buck point of view.



.


----------



## zheka

If any of you are curious about what 1.8 ft thick rockwool absorber fully covering the back wall would do to the long axis modes, head over to this thread in the DIY forum to find out:


http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12 


posts of interest:

http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12#post_24127058 

http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12/30#post_24130836 

http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12/30#post_24139987


----------



## BasementBob




> Quote:
> Originally Posted by *zheka*  /t/255432/acoustical-treatments-master-thread/9870#post_24155916
> 
> 
> If any of you are curious about what 1.8 ft thick rockwool absorber fully covering the back wall would do to the long axis modes,


Yep, nice result.

I remain curious about your overall impressions of the sound in the room when you're done, and what you're going to cover that with.



Reminded me of Philip Newell's Non-Environment Room (13' tall room, with 5' of insulation in the ceiling, 3' of insulation on the back wall, 2' on left and right walls, and the front wall and floor reflective).


and a little of that pile of insulation in RoyalDevice's room:
http://www.bobgolds.com/royaldevice_SubwooferHorn_FiberglassCurtain_34a.jpg 
http://www.royaldevice.com/custom.htm


----------



## zheka




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9870#post_24156276
> 
> 
> 
> 
> Reminded me of Philip Newell's Non-Environment Room (13' tall room, with 5' of insulation in the ceiling, 3' of insulation on the back wall, 2' on left and right walls, and the front wall and floor reflective).
> 
> 
> and a little of that pile of insulation in RoyalDevice's room:
> http://www.bobgolds.com/royaldevice_SubwooferHorn_FiberglassCurtain_34a.jpg
> http://www.royaldevice.com/custom.htm



wow. thank you for the links!


BTW, that thread I linked to is not mine, I just wanted to share because I found the results so impressive.


----------



## wse




> Quote:
> Originally Posted by *zheka*  /t/255432/acoustical-treatments-master-thread/9870#post_24156548
> 
> 
> wow. thank you for the links!
> 
> BTW, that thread I linked to is not mine, I just wanted to share because I found the results so impressive.


----------



## artur9

Any suggestions for cost effective ceiling diffusers/absortbers? I am kind of imagining AT tiles that permit the sound to go right into SafeNSound in the joists. Or is that delusional?


----------



## Nightlord

3" boards lengthwise with 2" spacing.


----------



## artur9




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9870#post_24164427
> 
> 
> 3" boards lengthwise with 2" spacing.



You are suggesting that I replace the existing ceiling tiles with slats? Is that a DIY project or are such "ceiling slats" available for purchase?


And nothing in the 2" gaps? Not even fabric?


----------



## Holiday121

Is it ok to use velvet for Traps on the ceilings and side walls?


----------



## Nightlord




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9870#post_24168425
> 
> 
> You are suggesting that I replace the existing ceiling tiles with slats? Is that a DIY project or are such "ceiling slats" available for purchase?
> 
> 
> And nothing in the 2" gaps? Not even fabric?



Well, I assumed an existing ceiling would be there. Otherwise you could have two layers of 3x1's, interleaved.


No idea what can be bought, for me this is definitely DIY.


----------



## artur9




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9870#post_24172328
> 
> 
> Well, I assumed an existing ceiling would be there. Otherwise you could have two layers of 3x1's, interleaved.
> 
> 
> No idea what can be bought, for me this is definitely DIY.



K. Well, I don't want to make the ceiling into a fire trap.










What I have is a drop ceiling with a 2'x2' grid. I can place this slatting into the existing grid and the space above it is to be filled with 3.5" SafeNSound with a 3" air gap (that's the spacing provided by the joists).


So one layer of 3x1s onto the grid or something like a layer of 3x1 then a layer of 3x2 notched to sit on the 3x1 in a checkerboard pattern? Or do you mean something else? The latter, as a DIY, is beyond my skills & equipment.


What are reasonable non-DIY solutions?


----------



## Nightlord




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9870#post_24172843
> 
> 
> K. Well, I don't want to make the ceiling into a fire trap.



Well, in my part of the world, wood panel ceilings are nothing unusual. I think you might buy acoustics panels made out of more firehazardous material than wood.










But sure, you can buy qrd-diffusors from somewhere as well. They might even do a better job, but will steal more height.


----------



## artur9




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/9870#post_24172878
> 
> 
> Well, in my part of the world, wood panel ceilings are nothing unusual. I think you might buy acoustics panels made out of more firehazardous material than wood.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> But sure, you can buy qrd-diffusors from somewhere as well. They might even do a better job, but will steal more height.



I saw one somewhere but it was extraordinarily price prohibitive - like almost $200 per tile.


I was thinking of making my own tiles out of AT fabric but wife shot that down.


----------



## Nightlord




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9870#post_24172881
> 
> 
> I saw one somewhere but it was extraordinarily price prohibitive - like almost $200 per tile.
> 
> 
> I was thinking of making my own tiles out of AT fabric but wife shot that down.



Yeah, that's why I'm making my own diffusors for the side walls... I'll be needing 32 in total and they cost $130ish/each.


----------



## jlpowell84

Ok I am finally going to quit procrastinating and build my soffit traps. I determined 15x15 is the biggest I can go without taking over my living room yet still being effective. I also have a bunch of Roxul AFB but using the air flow resistivity calculator proves the pink fluffy is the best for soffit bass traps. Or anything over 8-9 inches thick. But who is going to have that on their walls as reflection panels lol. Basically I plan on cutting a piece of 3/8 plywood 15x15 and then four 1x2 vertical pieces in each corner. I have 7 five footers to build and then three custom length to fill three gaps. That will cover both from L and R corners, the ceiling to wall junction along the front tv wall, and then 10ft back from the front wall on the L and R ceiling to wall junctions. I am going to get a roll of 15x9.25 and a roll of 15x6.5, so 15x15.75. I planned on the one sided paper style (sorry don't know terminology) then use a stapler to tack to the top pieces of plywood so they don't sag. Will I have any problems with the horizontal ones for along the ceiling to wall junction sagging? It's only 15.75 inches so it seems they would be fine. I have black micro suede fabric from ATS acoustics. But only going to wrap the two sides facing the room with a slight overlap to hide the two sides hidden by the wall. I will find something that will keep the insulation in. Any ideas for a cheap but effective netting or something so we don't get fiberglass all over. All suggestions welcome









http://www.lowes.com/ProductDisplay?partNumber=180143-1722-B373&langId=-1&storeId=10151&productId=3018364&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1 

http://www.lowes.com/pd_177781-1722-B390_4294925567__?productId=3141353&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FgoToProdList%3Dtrue%26Ns%3Dp_product_qty_sales_dollar%7C1&facetInfo=


----------



## artur9

Quoting/crossposting myself here as I haven't gotten what I was looking for in the other thread (and it took me 40min to write this










> Quote:
> Originally Posted by *artur9*  /t/1449924/simplified-rew-setup-and...nd-how-to-interpret-graphs/7830#post_24187821
> 
> 
> How do I use the ETC (or other measure) to decide between the following materials to treat my ceiling?
> 
> 
> I want to basically eliminate the ceiling as a source of reflections but I do not want the room to be too dead.
> 
> 
> .....................................................125HZ...250HZ...500HZ...1000HZ...2000HZ...4000HZ...NRC
> 
> 703, plain, on wall....1" (25mm) ........0.11......0.28.........0.68........0.90.....0.93......0.96....0.70
> 
> 703, plain 16" air gap 1" (25mm)........0.65......0.94.........0.76........0.98.....1.00.....1.14.....0.90
> 
> FINE FISSURED................................0.35......0.34.........0.55........0.72......0.65......0.62...0.55
> 
> 
> The first 2 are from Bob Gold's excellent site .
> 
> The 3rd is from Armstrong's product literature .
> 
> 
> I included the 2nd number as these will be drop ceiling tiles and there will be an air gap behind them. Up until I fill the joist area with SafeNSound.
> 
> 
> In case you're curious, the first two are driven by these black ceiling tiles on eBay
> 
> 
> The 3rd is Armstrong's Fine Fissured Homestyle tiles available at Lowes.


----------



## MALIX




> Quote:
> Originally Posted by *jlpowell84*  /t/255432/acoustical-treatments-master-thread/9870#post_24188162
> 
> 
> Ok I am finally going to quit procrastinating and build my soffit traps. I determined 15x15 is the biggest I can go without taking over my living room yet still being effective. I also have a bunch of Roxul AFB but using the air flow resistivity calculator proves the pink fluffy is the best for soffit bass traps. Or anything over 8-9 inches thick. But who is going to have that on their walls as reflection panels lol. Basically I plan on cutting a piece of 3/8 plywood 15x15 and then four 1x2 vertical pieces in each corner. I have 7 five footers to build and then three custom length to fill three gaps. That will cover both from L and R corners, the ceiling to wall junction along the front tv wall, and then 10ft back from the front wall on the L and R ceiling to wall junctions. I am going to get a roll of 15x9.25 and a roll of 15x6.5, so 15x15.75. I planned on the one sided paper style (sorry don't know terminology) then use a stapler to tack to the top pieces of plywood so they don't sag. Will I have any problems with the horizontal ones for along the ceiling to wall junction sagging? It's only 15.75 inches so it seems they would be fine. I have black micro suede fabric from ATS acoustics. But only going to wrap the two sides facing the room with a slight overlap to hide the two sides hidden by the wall. I will find something that will keep the insulation in. Any ideas for a cheap but effective netting or something so we don't get fiberglass all over. All suggestions welcome
> 
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.lowes.com/ProductDisplay?partNumber=180143-1722-B373&langId=-1&storeId=10151&productId=3018364&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1
> 
> http://www.lowes.com/pd_177781-1722-B390_4294925567__?productId=3141353&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FgoToProdList%3Dtrue%26Ns%3Dp_product_qty_sales_dollar%7C1&facetInfo=



Yep I'm in The same Boat. I am building my room out now and have 26" W x 9"H soffit bass traps going in. I'll also be using pink fluffy and am wondering about what to cover the pink fluff with. In addition I have 2ft w 3 ft deep x columns in the corners behind my screen wall which will house my subs on the floor, but from the top of the subs to the ceiling will be filled with pink fluffy.


For netting the insulation in the soffits I am consideriing netting as you are.. But there is also the possibillity of 3 mil or 6 mil plastic. or kraft paper. Depending on what you want to do with the high frequencies of course.


----------



## zheka




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/8040#post_21109400
> 
> 
> I found some mineral wool today while out and about over lunch, but I couldn't find out if it would work for super chunk bass traps or for first point reflection panels.
> 
> 
> 
> The specs are:
> 
> 
> Thermafiber brand mineral wool "safing insulation".
> 
> 
> 
> 4 inch thick, 2 foot x 4 foot panels
> Thermafiber R-16.8 Mineral Wool
> 
> 
> 
> I can't find a pcf rating anywhere... Not on the packaging, not at Menards.com, not at Thermafiber's web site.
> 
> 
> 
> Maybe it is completely wrong. I just noticed that the in-store price was on sale for about $10 cheaper for a 5 sheet bundle the online price is normally less than in-store, but then you have to get it shipped.
> 
> 
> 
> Any thoughts? Sale price is good for 2 more days, so if this will work OK, I might stock up on it now.



I could not resist to bring up this old post because I think this material may be a very good and inexpensive choice for DIY broadband absorption panels.


I called Thermafiber. It is 4pcf which is optimal for mineral wool absorbers AFAIK.


They claim 1.01 absorption coefficient @125Hz for 4" 4pcf panels.

http://www.thermafiber.com/Portals/0/PDF/NRC%20Data%20Sheet.pdf 


It is also lighter than ROXUL rockwool panels I used before. It maybe perfect for the ceiling cloud I am planing.


----------



## wse


I found 100% cotton panels


----------



## zheka




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9870#post_24204165
> 
> 
> I found 100% cotton panels


UltraTouch ?


----------



## purbeast

I posted this over in the DIY acoustical panel thread but I think here would be a good place to ask as well.


Let me just preface this as I'm 100% noob to this whole acoustical panel thing and the correct placement and materials to use, and I'm primarily making mine for aesthetic reasons because my H T walls are bare, but since I'm putting stuff on the walls I figured I'd make them somewhat functional.


I've already made the frames and know where I'm going to place them, again, purely for aesthetic reasons.


The frames are 2' x 3' and are 2.5" thick. I have a .5" back on them and plan to use a .5" french cleat as well to make it flush, then put 2" thick insulation in there.


I was planning on getting some 2" thick Roxul insulation.


Being a total noob to this, I was wondering if there are any differences between the following 3 types.


- Roxul Rockboard 80 - http://www.atsacoustics.com/item--Roxul-Rockboard-80-Case-of-6--RB80.html 

- Roxul RHT 80 - http://www.buyinsulationproductstore.com/servlet/the-368/Roxul-Mineral-Wool-Rockwool/Detail 

- Roxul Comfort Board - a local guy is getting back to me with prices on these.


Now I saw this link here that shows the different properties between the materials - http://www.bobgolds.com/AbsorptionCoefficients.htm 


However I only see the RHT 80 on there, and I'm confused because it has RXF/RHT as the listing, and it appears to be 5.9pcf whereas the webpage listing that is selling it says it's 8pcf. That stuff is about $10 cheaper than purchasing the Rockboard 80 from ATS after shipping. I haven't gotten a price back on the local Comfort Board yet, but I do know they said that stuff comes in packs of 7, whereas this stuff comes in packs of 6. Either way it will be more than enough.


Then I'm wondering if I'd notice any difference between the 60 and 80 versions of this stuff?


So me, being a total noob about this, do you guys think that in reality I would notice much, if any difference at all, between any of these materials? What about between the 60 and 80 versions? I wanted to order this stuff soon because the artwork for my panels is being shipped very soon and I'd like to get them up and on the wall as soon as I can.


Thanks.


----------



## mikela

Question:


I am building my theater and currently have 5/8" drywall attached to the ceiling joists. They are 12" deep and filled with insulation. I was planning on putting another layer of 5/8" drywall with Green Glue. Would running channel strip across the current drywall (attaching to the joists) and installing 2 layers of 5/8" dry wall to the channel ( with Green Glue in between) be a more effective sound barrier? I am just hesitant to rip down the original drywall or will leaving it there make matters worse.


Mike


----------



## BasementBob




> Quote:
> Originally Posted by *purbeast*  /t/255432/acoustical-treatments-master-thread/9870#post_24204290
> 
> 
> - Roxul Rockboard 80
> 
> - Roxul Comfort Board



Acoustical coefficients for those can be found at
http://www.roxul.com/files/RX-NA_EN/pdf/Sell%20Sheets/RockBoard%20Sell%20Sheet.pdf 
http://www.roxul.com/files/RX-NA_EN/pdf/ComfortBoard%20IS.pdf 


> Quote:
> Originally Posted by *purbeast*  /t/255432/acoustical-treatments-master-thread/9870#post_24204290
> 
> 
> do you guys think that in reality I would notice much, if any difference at all, between any of these materials?


I doubt you'd be able to notice anything.

The Roxul Rockboard 80 vs Roxul Comfort Board, at 2", have the same coefficients, so I'd presume you wouldn't be able to measure anything different either.


> Quote:
> Originally Posted by *purbeast*  /t/255432/acoustical-treatments-master-thread/9870#post_24204290
> 
> 
> What about between the 60 and 80 versions?


For 2" thick I would chose the 80 version, and not the 60 version, for general stock. Because the 80 is a bit more broadband at 125 hz than the 60.




(As for what makes sense in your room, I have no idea.)


----------



## purbeast




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/9870#post_24205743
> 
> 
> Acoustical coefficients for those can be found at
> http://www.roxul.com/files/RX-NA_EN/pdf/Sell%20Sheets/RockBoard%20Sell%20Sheet.pdf
> http://www.roxul.com/files/RX-NA_EN/pdf/ComfortBoard%20IS.pdf
> 
> I doubt you'd be able to notice anything.
> 
> The Roxul Rockboard 80 vs Roxul Comfort Board, at 2", have the same coefficients, so I'd presume you wouldn't be able to measure anything different either.
> 
> For 2" thick I would chose the 80 version, and not the 60 version, for general stock. Because the 80 is a bit more broadband at 125 hz than the 60.
> 
> 
> 
> 
> (As for what makes sense in your room, I have no idea.)



Thanks for all the info. I actually found the RHT 80 stuff on the Roxul website after seeing that you linked to a bunch of PDF files on there. It's located here.

http://www.roxul.com/files/RX-NA_EN/pdf/RHT80-3-30-10.pdf 


It appears the all of the RHT 80 values are higher other than the very low end, which is .39 as oppose to .43. The others seem to range around .4 or so higher, except in the 500hz range it appears to be like .12 higher.


Realistically, being as noob as I am to all of this, would I hear an actual difference between these? Or am I starting to just over think this and I should just go grab one and just be happy with it heh?


----------



## zheka

purbeast,


Have you considered doing 4" panels? It is a better choice all around when possible. And it's likely to be cheaper too because you can use lower density material. A set of 5 4" Thermafiber 2x4 panels is around $40 after rebate in Menards now.


----------



## purbeast




> Quote:
> Originally Posted by *zheka*  /t/255432/acoustical-treatments-master-thread/9870#post_24206254
> 
> 
> purbeast,
> 
> 
> Have you considered doing 4" panels? It is a better choice all around when possible. And it's likely to be cheaper too because you can use lower density material. A set of 5 4" Thermafiber 2x4 panels is around $40 after rebate in Menards now.



I didn't consider them just because I think 4" would be a little too bulky for what i'm going for. Even the 2.5" thick panels are even pushing it but I think they will look fine on the wall. I actually already have 6 of them ready to be filled, and I'm just waiting for my printed fabric to arrive as well.


----------



## granroth

Are diffusers "generic" or are they tuned for specific purposes?


I ask because I have a Kinetics Rear Wall Diffuser from a previous theater of mine, circa 2003. It's completely covered by fabric, so I have no idea what it looks like inside. I am thinking about removing the fabric and seeing if I can replicate the design of the internals and make several more of them.


But would that be a worthwhile endeavor, or since that diffuser was designed for rear walls, then it wouldn't do a great job on the side walls?


----------



## myfipie




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/9870#post_24207321
> 
> 
> Are diffusers "generic" or are they tuned for specific purposes?
> 
> 
> I ask because I have a Kinetics Rear Wall Diffuser from a previous theater of mine, circa 2003. It's completely covered by fabric, so I have no idea what it looks like inside. I am thinking about removing the fabric and seeing if I can replicate the design of the internals and make several more of them.
> 
> 
> But would that be a worthwhile endeavor, or since that diffuser was designed for rear walls, then it wouldn't do a great job on the side walls?



Diffusors are made to diffuse/scatter sound at a certain frequency ranges. This is done but calculating the unit you are working with. More about how diffusion works.
http://gikacoustics.com/video-how-diffusion-works/


----------



## granroth




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24208058
> 
> 
> Diffusors are made to diffuse/scatter sound at a certain frequency ranges. This is done but calculating the unit you are working with. More about how diffusion works.
> http://gikacoustics.com/video-how-diffusion-works/



That video doesn't really make any references to scattering based on frequency and instead focuses on how evenly it is scattered. I'm assuming that that refers to the width of frequencies that are evenly scattered. I do see in the descriptions of the GIK products that some frequency ranges are given.


More to point for my question, the frequencies appear to be roughly the same for all the products, and they also make no reference to being particular to any given location.


That strongly implies to me that the Kinetics Rear Wall Diffuser is likely not tuned to some set of frequencies that are specific to a rear wall. If that was the case, then does it make sense that the design could be perfectly replicated and re-used all over a theater with appropriate woodworking skills?


OR, is it the case that rear walls do, indeed, have a unique set of frequencies that should be diffused and the Kinetics unit might very well be tuned to that?


----------



## TMcG




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/9870#post_24211196
> 
> 
> That video doesn't really make any references to scattering based on frequency and instead focuses on how evenly it is scattered. I'm assuming that that refers to the width of frequencies that are evenly scattered. I do see in the descriptions of the GIK products that some frequency ranges are given.
> 
> 
> More to point for my question, the frequencies appear to be roughly the same for all the products, and they also make no reference to being particular to any given location.
> 
> 
> That strongly implies to me that the Kinetics Rear Wall Diffuser is likely not tuned to some set of frequencies that are specific to a rear wall. If that was the case, then does it make sense that the design could be perfectly replicated and re-used all over a theater with appropriate woodworking skills?
> 
> 
> OR, is it the case that rear walls do, indeed, have a unique set of frequencies that should be diffused and the Kinetics unit might very well be tuned to that?



Both are important so you don't have inconsistency or frequency "hot spots" across the face of the panel.


Given that most of the products use the same fiberglass suppliers and try to tweak the performance of their product with different densities, thicknesses and constructions....it stands to reason that most of these products would be very similar.


Most theaters follow the rule of "dead front live rear", which takes careful consideration of each panel type required for a given location in the theater.


----------



## purbeast

So just one last noob question before I make my purchase.


Is there really any audible difference between a coefficient in the 125hz range of .04? Will there be an audible difference from .39 and .43? Or is this comparison peanuts at this point and just not worth worrying about?


----------



## HopefulFred

I wouldn't worry about it. IF the two samples were tested by the same guy in the same lab, then MAYBE you could have confidence in the difference and hope to hear a difference. (IMO)


----------



## purbeast




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9900#post_24211775
> 
> 
> I wouldn't worry about it. IF the two samples were tested by the same guy in the same lab, then MAYBE you could have confidence in the difference and hope to hear a difference. (IMO)



Okay thanks. I just know nothing about this so just want to be sure I get the best thing lol. It's like a $10 difference between the Roxul RHT80 and Roxul Rockboard 80, so i'm just going to go with the RHT80 since it's cheaper.


----------



## granroth




> Quote:
> Originally Posted by *TMcG*  /t/255432/acoustical-treatments-master-thread/9800_100#post_24211542
> 
> 
> Both are important so you don't have inconsistency or frequency "hot spots" across the face of the panel.
> 
> 
> Given that most of the products use the same fiberglass suppliers and try to tweak the performance of their product with different densities, thicknesses and constructions....it stands to reason that most of these products would be very similar.
> 
> 
> Most theaters follow the rule of "dead front live rear", which takes careful consideration of each panel type required for a given location in the theater.



So I'm getting that diffusers can certainly be tuned to specific frequencies and that there are even calculators for creating QFD skyline diffusers that can treat exactly the range that you want. I'm not easily finding that in the commercial offerings, though. If I go to the GIK site, I see that they have four diffuser options, that each deal with roughly the same frequency range (give or take). That implies that creating a diffuser that does scatter a specific range (maybe even an MLS variant) would be a relatively rare occurrence, used only in very highly tuned theaters or studios.


IF that's true (and I have no idea if it is), then that further implies that if "a diffuser" would be called for in any given location, then pretty much any commercial diffuser will do the job.


IF I then follow that conclusion, then that implies that if I replicate the design of a commercial diffuser, then it should work just fine anywhere else I put it.


This is the point where I hope that somebody either confirms my conclusions or tells me why I'm wrong (likely the latter, since I'm quite the acoustic noob)


----------



## jlpowell84




> Quote:
> Originally Posted by *MALIX*  /t/255432/acoustical-treatments-master-thread/9870#post_24203693
> 
> 
> Yep I'm in The same Boat. I am building my room out now and have 26" W x 9"H soffit bass traps going in. I'll also be using pink fluffy and am wondering about what to cover the pink fluff with. In addition I have 2ft w 3 ft deep x columns in the corners behind my screen wall which will house my subs on the floor, but from the top of the subs to the ceiling will be filled with pink fluffy.
> 
> 
> For netting the insulation in the soffits I am consideriing netting as you are.. But there is also the possibillity of 3 mil or 6 mil plastic. or kraft paper. Depending on what you want to do with the high frequencies of course.



Plastic yes I like it! as far as the finish side I have the black micro suede from ATS acoustics. I actually draped some over my two submersives and LR mains and measured. They begin to roll off right at 2,000hz pretty steadily and consistently. Can be a good thing if you don't want to over deaden a room.


----------



## zheka




> Quote:
> Originally Posted by *jlpowell84*  /t/255432/acoustical-treatments-master-thread/9900#post_24212904
> 
> 
> Plastic yes I like it! as far as the finish side I have the black micro suede from ATS acoustics. I actually draped some over my two submersives and LR mains and measured. They begin to roll off right at 2,000hz pretty steadily and consistently. Can be a good thing if you don't want to over deaden a room.



the HF roll-off with the micro suede may be due to absorption, not reflection. plastic is probably a safer choice if limiting HF absorption is the goal.


----------



## artur9

I know pepar has said in the past that nothing has improved his sound as much as putting in rear absorbers.


I just put in ceiling absorbers and, subjectively, they have made the most difference. From the multi-channel POV it's like night and day


----------



## myfipie




> Quote:
> the HF roll-off with the micro suede may be due to absorption, not reflection. plastic is probably a safer choice if limiting HF absorption is the goal.



Actually, if you want to really do it right, then use a slat design which will reflect/diffuse/scatter upper frequencies. This is ours but there are other DIY solutions out there.
http://gikacoustics.com/scatter-plate-product-video/


----------



## NicksHitachi

Hi all,


Just wanted to share my current project with acoustic treatment. I've learned a lot from this thread and still pop by once in a while. Maybe someone will find this interesting.


I'm on the final round of acoustic treatment for my theater. Originally I went with BB absorbers and found as expected that as I approached my goals for treatment that the life of the room decreased. I decided to incorporate diffusion into my design. I found a binary amplitude pattern online as well as the inverse for that pattern. I contacted a local CNC machine shop which converted the image file to a CNC file and had the masonite CNCed with 1/2" holes.


Heres the current progress:

 

 

 

 

 


The diffusor plates are going to be appliques on the front of the diffusors so if I see any glare issues I can remove the applique and convert the panels back to BB.


----------



## cuzed2

Nick,


Been awhile since I stopped by, and whoa what do I find ?

Is that 16, 2'x4' diffusor panels I am seeing?


Looking forward to the results!


----------



## myfipie

wow Nick that is great! And yes a CNC is the way to go.


----------



## saprano

I'm going to buy drapes for my 3 73" long windows behind my setup. In the meantime i put up blankets to block out the sun, and wow, i don't think i need to do any other acoustic treatment to my room. With no reflection coming from the front anymore the sound is so good. Everything has such focus and detail. Dialog sounds like the person in the room with me instead of coming from a speaker. The sound from my speakers is much closer and clearer if that makes any sense. Even the surround channels. It made me think...do i really need to buy new speakers? Ha.


I think putting up curtains will be enough. I already have a thick area rug. Anything else and i think the room would become too dead sounding. Some reflection is good.


----------



## KJSmitty




> Quote:
> Originally Posted by *saprano*  /t/255432/acoustical-treatments-master-thread/9900#post_24236030
> 
> 
> I'm going to buy drapes for my 3 73" long windows behind my setup. In the meantime i put up blankets to block out the sun, and wow, i don't think i need to do any other acoustic treatment to my room. With no reflection coming from the front anymore the sound is so good. Everything has such focus and detail. Dialog sounds like the person in the room with me instead of coming from a speaker. The sound from my speakers is much closer and clearer if that makes any sense. Even the surround channels. It made me think...do i really need to buy new speakers? Ha.
> 
> 
> I think putting up curtains will be enough. I already have a thick area rug. Anything else and i think the room would become too dead sounding. Some reflection is good.



I had a similar experience.

Been thinking about treatments for years for our modest sealed/dedicated HT room - just haven't committed to it due to it sounds pretty good yet I do have a bit of slap echo etc. This month they started on our house renovations and I had to place items from the guest BR into the HT. Basically I have a king size mattress on the left wall and the box springs on the right wall. It was quite evident during the first movie we watched last week. Like you mentioned, more detail, clear vocals etc.


I know I am convinced now that treatments will happen as soon as the current remodel is complete.


Cheers


----------



## myfipie




> Quote:
> Originally Posted by *saprano*  /t/255432/acoustical-treatments-master-thread/9900#post_24236030
> 
> 
> I'm going to buy drapes for my 3 73" long windows behind my setup. In the meantime i put up blankets to block out the sun, and wow, i don't think i need to do any other acoustic treatment to my room. With no reflection coming from the front anymore the sound is so good. Everything has such focus and detail. Dialog sounds like the person in the room with me instead of coming from a speaker. The sound from my speakers is much closer and clearer if that makes any sense. Even the surround channels. It made me think...do i really need to buy new speakers? Ha.
> 
> 
> I think putting up curtains will be enough. I already have a thick area rug. Anything else and i think the room would become too dead sounding. Some reflection is good.



Putting up blankets or heavy curtains will certainly help with upper frequencies but the man problem in a small room is the low end. Things like blankets and curtains just are not thick enough to have an impact on them. That is the reason we use bass trapping to tighten up the low end.
http://gikacoustics.com/video_bass-traps/


----------



## nickbuol




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/9900#post_24238399
> 
> 
> Putting up blankets or heavy curtains will certainly help with upper frequencies but the man problem in a small room is the low end. Things like blankets and curtains just are not thick enough to have an impact on them. That is the reason we use bass trapping to tighten up the low end.
> http://gikacoustics.com/video_bass-traps/



+1


@ saprano - In my *personal* opinion, the drapes and higher frequency control is what people notice the most, however, you are only helping a relatively small portion of the frequency issues in any room. Now, I know that everyone has a different bang-for-their-buck (or bang-for-their-amount-of-effort-that-they-want-to-put-into-it) cut off point, and while I won't tell you that you "suck for not doing more" because it is your room/dollar/effort, but let me just say that there is a lot more than can be done without a huge amount of expense and minimal effort should you so choose.


Let me give you an example. Back in 1997, I was in a home theater with 8 actual movie theater seats on a double riser behind a comfy couch up front. (Keep in mind that "home theater seating" like today didn't really exist, at least for someone without a million dollar home.) The theater had some sort of goofy DIY 11.2 audio setup back when the best signal you could send it was 5.1 DTS and 5.1 Dolby via DVD. Anyway, the room had a carpeted floor, the walls had really thick felt that was glue to them with contact cement, and the ceiling was covered with a thinner felt and had a variety of different brightness (and a couple of colors) Christmas light strands all attached to the ceiling in a night sky pattern, and then covered with that thinner felt so that it muted the light, but was still neat to see in the dark. So this whole crazy room was a massive echo box before the felt went up (I was there) and afterwards, it was unbelievable how much better everything sounded. And that was will felt put on the walls like wallpaper. It was really a night and day difference acoustically, however, looking back, the bass wasn't tight, it was boomy, and there was just some clarity missing to anything that wasn't coming from the tweeters. Again, it sounded really nice back then. Fast forward to today, I've got a modest theater, nothing real fancy at all. It was the biggest echo chamber I have ever been in before the carpet went in, and heck, it had a lot of echo AFTER the carpet. I then put in some bass traps and treatments on the front wall behind my speakers and screen. It helped a LOT and I would say was a good amount better than the "felt theater, but I still wanted things even more clear. I then put up the thickest acoustical panels on the walls that I could (and that the wife would allow) at just 3.5" thick on the side walls, and 5.5" thick on the back wall, and holy crap. SO much better. Not just with the dialog for movies, but the bass had more punch without being boomy, the surround was so much better, and so forth. The biggest improvement for dialog came, obviously, from the panels closest to the speakers, but the rest of the frequency getting tamed made a really amazing difference overall.


I know that I could use a little more absorption and maybe some diffusion, but this is what I am at today and it is great to me.


PS. I was the one with the goofy "felt theater" and its DIY 11.2 sound (long story on getting that to work.)


----------



## saprano




> Quote:
> Originally Posted by *KJSmitty*  /t/255432/acoustical-treatments-master-thread/9900#post_24238205
> 
> 
> I had a similar experience.
> 
> Been thinking about treatments for years for our modest sealed/dedicated HT room - just haven't committed to it due to it sounds pretty good yet I do have a bit of slap echo etc. This month they started on our house renovations and I had to place items from the guest BR into the HT. Basically I have a king size mattress on the left wall and the box springs on the right wall. It was quite evident during the first movie we watched last week. Like you mentioned, more detail, clear vocals etc.
> 
> 
> I know I am convinced now that treatments will happen as soon as the current remodel is complete.
> 
> 
> Cheers



It's a crazy experience isnt it? I'm not talking subtle differences either, this was a massive improvement in SQ. And this is with no EQ from my receiver. I wonder if EQ would improve the sound further or mess with it?


Speaking of slap echo, just laying down an area rug helped with that. It got rid of it completely.


> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/9900#post_24238399
> 
> 
> Putting up blankets or heavy curtains will certainly help with upper frequencies but the man problem in a small room is the low end. Things like blankets and curtains just are not thick enough to have an impact on them. That is the reason we use bass trapping to tighten up the low end.
> http://gikacoustics.com/video_bass-traps/



Yes I was just talking about mid and high frequencies, bass still could be worked on. I only have 1 coner on my room so I won't need allot of bass traps.


----------



## myfipie




> Quote:
> Yes I was just talking about mid and high frequencies, bass still could be worked on. I only have 1 coner on my room so I won't need allot of bass traps.



You can also use floor to wall and or ceiling to wall corners around the room for trapping. This test shows you all the different corners a room has available.
http://gikacoustics.com/video-testing-corner-bass-trap-placement/


----------



## saprano




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9900#post_24238704
> 
> 
> +1
> 
> 
> @ saprano - In my *personal* opinion, the drapes and higher frequency control is what people notice the most, however, you are only helping a relatively small portion of the frequency issues in any room. Now, I know that everyone has a different bang-for-their-buck (or bang-for-their-amount-of-effort-that-they-want-to-put-into-it) cut off point, and while I won't tell you that you "suck for not doing more" because it is your room/dollar/effort, but let me just say that there is a lot more than can be done without a huge amount of expense and minimal effort should you so choose.
> 
> 
> Let me give you an example. Back in 1997, I was in a home theater with 8 actual movie theater seats on a double riser behind a comfy couch up front. (Keep in mind that "home theater seating" like today didn't really exist, at least for someone without a million dollar home.) The theater had some sort of goofy DIY 11.2 audio setup back when the best signal you could send it was 5.1 DTS and 5.1 Dolby via DVD. Anyway, the room had a carpeted floor, the walls had really thick felt that was glue to them with contact cement, and the ceiling was covered with a thinner felt and had a variety of different brightness (and a couple of colors) Christmas light strands all attached to the ceiling in a night sky pattern, and then covered with that thinner felt so that it muted the light, but was still neat to see in the dark. So this whole crazy room was a massive echo box before the felt went up (I was there) and afterwards, it was unbelievable how much better everything sounded. And that was will felt put on the walls like wallpaper. It was really a night and day difference acoustically, however, looking back, the bass wasn't tight, it was boomy, and there was just some clarity missing to anything that wasn't coming from the tweeters. Again, it sounded really nice back then. Fast forward to today, I've got a modest theater, nothing real fancy at all. It was the biggest echo chamber I have ever been in before the carpet went in, and heck, it had a lot of echo AFTER the carpet. I then put in some bass traps and treatments on the front wall behind my speakers and screen. It helped a LOT and I would say was a good amount better than the "felt theater, but I still wanted things even more clear. I then put up the thickest acoustical panels on the walls that I could (and that the wife would allow) at just 3.5" thick on the side walls, and 5.5" thick on the back wall, and holy crap. SO much better. Not just with the dialog for movies, but the bass had more punch without being boomy, the surround was so much better, and so forth. The biggest improvement for dialog came, obviously, from the panels closest to the speakers, but the rest of the frequency getting tamed made a really amazing difference overall.
> 
> 
> I know that I could use a little more absorption and maybe some diffusion, but this is what I am at today and it is great to me.
> 
> 
> PS. I was the one with the goofy "felt theater" and its DIY 11.2 sound (long story on getting that to work.)



Yeah like I mentioned above, I admit the bass still has to be worked on. It's just that the improvement to the high frequencies was so good it made me think what else do I really need.


The ceiling and side walls are still bare, but I think adding anything else will make the sound too dead. I don't know, I'm just guessing based off how it currently sounds. My room is 16.4' long, 11.6' wide and 9.4' high. It's not that big so maby the blankets, and when I get curtains, is already absorbing enough reflections?


----------



## saprano




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/9900#post_24238793
> 
> 
> You can also use floor to wall and or ceiling to wall corners around the room for trapping. This test shows you all the different corners a room has available.
> http://gikacoustics.com/video-testing-corner-bass-trap-placement/



There's a door near the corner so i would only need to do, or can do, the upper corner near the ceiling.


----------



## artur9

So, I have two questions one rather specific the other extremely general.


(1) If I'm sitting 14 ft from the mains, does that mean I have to get reflections under 20db in under 14ms (more or less, speed of sound etc)?


(2) There are treatments to reduce ringing (absorption), treatments to reduce reflections/echo(absorption & diffusion). Are there other kinds of passive treatments?


----------



## myfipie




> Quote:
> (1) If I'm sitting 14 ft from the mains, does that mean I have to get reflections under 20db in under 14ms (more or less, speed of sound etc)?



The 14 ft does not matter. What you want is to have any reflection that is 20ms from zero (zero being the length from speaker to listening spot) down 20db if possible. That is a general rule but all rooms can be a bit different. Does that make sense?


> Quote:
> (2) There are treatments to reduce ringing (absorption), treatments to reduce reflections/echo(absorption & diffusion). Are there other kinds of passive treatments?


Basically those are the ones.

See if this helps
http://www.gikacoustics.com/understanding-different-bass-trapping/


----------



## artur9




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/9900#post_24250606
> 
> 
> The 14 ft does not matter. What you want is to have any reflection that is 20ms from zero (zero being the length from speaker to listening spot) down 20db if possible. That is a general rule but all rooms can be a bit different. Does that make sense?



Yes, thanks. Sounds so easy!


----------



## mikela

I am building my theater and currently have 5/8" drywall attached to the ceiling joists. They are 12" deep and filled with insulation. I was planning on putting another layer of 5/8" drywall with Green Glue. Would running channel strip across the current drywall (attaching to the joists) and installing 2 layers of 5/8" dry wall to the channel ( with Green Glue in between) be a more effective sound barrier? I am just hesitant to rip down the original drywall or will leaving it there make matters worse.


Mike


----------



## HopefulFred

You leave a lot of isolation on the table if you leave the drywall there. http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ 


This question is a good one, and comes up fairly regularly - it's better for a different thread, however, as it's sound isolation/soundproofing, not acoustical treatment. There's good reading here: http://www.avsforum.com/t/1509173/soundproofing-master-thread


----------



## mikela

Thanks! Somehow I knew I would have to rip that drywall out. I am installing an IB single bass array with 12 18 inchers, so probably worth it to do it right.


----------



## lbrown105




> Quote:
> Originally Posted by *mikela*  /t/255432/acoustical-treatments-master-thread/9900#post_24253712
> 
> 
> Thanks! Somehow I knew I would have to rip that drywall out. I am installing an IB single bass array with 12 18 inchers, so probably worth it to do it right.


my biggest question about the drywall and clips is how does it affect the sound in the room with respect to the bass decay. Knowing the flex of the drywall must have effects on the bass performance inside the room, are you also curious about that? I could not find a good answer to that anywhere. Since you are considering this change I thought I would ask even though your original question is about sound isolation.


----------



## Nyal Mellor




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/9900#post_24256833
> 
> 
> my biggest question about the drywall and clips is how does it affect the sound in the room with respect to the bass decay. Knowing the flex of the drywall must have effects on the bass performance inside the room, are you also curious about that? I could not find a good answer to that anywhere. Since you are considering this change I thought I would ask even though your original question is about sound isolation.



Well I've never installed clips on single drywall, or seen a room with that done. My company does a lot of acoustic consulting so we see and measure quite a few rooms. The below are my observations from this work. I have a bunch of measurements of bass freqeuncy and decay vs. wall construction to back this up, but no lab tests.


Yes, single drywall flexes and absorbs bass but it also resonates at certain frequencies and rings on after the bass sound waves put out by the speakers/subs stop.


Double drywall with green glue is much stiffer so absorbs less bass but also resonates and rings less, as you would expect from a more damped structure.


The addition of clips to the double drywall with green glue increases absorption in the range below about 60Hz.


----------



## lbrown105




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9900#post_24257680
> 
> 
> Well I've never installed clips on single drywall, or seen a room with that done. My company does a lot of acoustic consulting so we see and measure quite a few rooms. The below are my observations from this work. I have a bunch of measurements of bass freqeuncy and decay vs. wall construction to back this up, but no lab tests.
> 
> 
> Yes, single drywall flexes and absorbs bass but it also resonates at certain frequencies and rings on after the bass sound waves put out by the speakers/subs stop.
> 
> 
> Double drywall with green glue is much stiffer so absorbs less bass but also resonates and rings less, as you would expect from a more damped structure.
> 
> 
> The addition of clips to the double drywall with green glue increases absorption in the range below about 60Hz.


thanks your experience and comments are appreciated. I am about to make the decision to replace my drop ceiling (R19 above) with DD+GG on whisper clips. I had been apprehensive that the bass decay above 50 hz may get worse. Right now I have really good bass decay down to about 55hz so after seeing your response I am hopeful that the overall bass will decay will get better. I will be able to use 2i n panels for mids/highs for first relection but I do not really have room for soffit traps around the perimeter of the room. I have a lot of measurements now and will post comparisons this spring after its complete. thx again


----------



## mtbdudex




> Quote:
> Originally Posted by *mikela*  /t/255432/acoustical-treatments-master-thread/9900#post_24253712
> 
> 
> Thanks! Somehow I knew I would have to rip that drywall out. I am installing an IB single bass array with 12 18 inchers, so probably worth it to do it right.


Post a link to your IB thread, I'd love to read it.



Sent from my iPad2 64GB using Tapatalk


----------



## nathan_h




> Quote:
> Originally Posted by *Holiday121*  /t/255432/acoustical-treatments-master-thread/9870#post_24170742
> 
> 
> Is it ok to use velvet for Traps on the ceilings and side walls?



Please define "okay". If it's very thick (you cannot blow through it) you'll lose the high frequency absorption capabilities of the trap, since those frequencies will be reflected back into the room.


If you can blow through the velvet, it's not too bad -- there will be impact, so you won't get the measured performance of the trap -- but it will work.


----------



## Aarghon

Hello people!


A while ago, I've built absorption panels, and the fabric used was good ol' plain 200 thread count flat sheets. It seems to work ok, it's breathable. But there's a small problem right now.


I want to build corner bass traps using the same fabric, but the 200 thread count is nowhere to be found grrr... I can get 300 thread count ones... Would it still be enough breathable, or it would be too tight woven and reflect the frequencies instead of absorbing them?



Thanks in advance!


----------



## NicksHitachi

^You might actually want to reflect HF on a bass trap, if all your treatments are BB youll have an uneven decay overabsorbing the HF.


If you dont have a spectral component that needs addressing in that corner its prob best to cover the absorption with 6mil plastic and then the fabric of your choice.


----------



## Aarghon

Nickshitachi : Hmmm ok so , basically, if I want to go the sheet way, it would even be better that the fabric wouldn't have the same "resistance" because the frequency requiring to be absorbed is not the same?


Thanks for your answer!


----------



## mtbdudex

When applying the 6mil plastic use some spray adhesive, you will get some membrane effects with doing that. Same reason some people use foil covered OC703 board with the foil facing into the acoustic space.



Via my iPhone 5s using Tapatalk


----------



## Aarghon

ok thanks for the trick mtb!


and nickshitachi, my absorption panels were designed to absorb high and mid frequencies from reflections... Didn't see the possible unbalancing of frequencies by over-absorbing some of them again with my corner bass traps... thanks again!


----------



## calimark

Can you guys take a look at this FR- I am concerned about the severe roll off.


The initial measures are nearfield (in room) and seating position.


The heavy roll off was measured after installing 2 corner traps, 10' tall with 24x24*34 triangles.


Is this roll off indicative of the bass traps? Or should I investigate otherwise?


Also, if I were to put plastic on the bass traps (to bring up the highs), what happens then if I treat the front wall for reflections?


----------



## Aarghon

Hello people!


I have a few questions about DYI acoustic treatments...


The first step I've done is absorption panels... I've made them with 3 inches rockwool... Safe'n'sound roxul..They are wooden framed, and I've sealed them on the back with tyvek construction paper (breathable wall insulator) I've left a small air gap between the panels and the wall. Do you think that it will do a sufficient absorption of reflections on the back wall? Hope it will mitigate high/mid frequencies at least.


My other question is about corner bass traps... I was planning using 2 panels of the same rockwool for a 6 inches deepness. If I add a 6mil plastic before wrapping them in fabric, do I need to do it only on the front of the panel? Or on the back too?


Finally... My worst fear is to over treat my small room, which is 12 x 12.... So here is what I would have: 3 absorption panels ( 3 x 24 x48 ) on the back wall, 2 room corners with bass traps from ground to ceiling ( 2 panels 6 x 24 x48 in each corner) and 4 amovible absorption panels on stands( same than those on the back wall, 2 on each side at first reflection points ) ... I can't treat the 2 room remaining corners with bass traps, since they are in the kitchen ...living room and kitchen are the same room , rectangular... So the living room is open on the right side, no wall there...Would it become too dead sounding that way?


Sorry for the multiple questions following another question hehe


Thanks in advance for all the invaluable help/info we get in here... AVSforum is the best place for audio on the net


----------



## Aarghon

If it can help to understand my rant , here is a superb architect plan of what it will look like ... If I do what I've described in the prior post!


----------



## Nighthawk26

I suppose I have a somewhat related situation to Aaghon. Perhaps someone could chime in with a litle a dual purpose anser.


My room is "dedicated" in the sense that 3 of it's sides are closed off as a 13.5'x20' room, with NO back wall. It opens up essentially there to the rest of the finished basement. Carpet in the theater area, and hardwood through the rest for the most part. The room is NOT soundproofed, just insulation and single layer drywall. I do have everthing behind my screen including 2 15" Martin Logan Dynamo 1500's. I with have Audessy EQT32 in my system, but at this time I'm in the middle of designing the walls. There will be 2 columns, wach having the side surround, and the rears are about 12 feet back from there. Essentially outside the "dedicated space. Behind the screen, I intend to use 2 layers of linacoustic, and I'm open to bass traps (703) in the corners. Aside from likely first reflection points, what else should I be looking into? I assume everything behind the screen will still be beneficial? ANything else I can put in the room thats not TOO obtrusive?


Thanks guys!


----------



## myfipie




> Quote:
> The first step I've done is absorption panels... I've made them with 3 inches rockwool... Safe'n'sound roxul..They are wooden framed, and I've sealed them on the back with tyvek construction paper (breathable wall insulator) I've left a small air gap between the panels and the wall. Do you think that it will do a sufficient absorption of reflections on the back wall? Hope it will mitigate high/mid frequencies at least.



You may want to increase the air gap but it should still work how you have it.


> Quote:
> My other question is about corner bass traps... I was planning using 2 panels of the same rockwool for a 6 inches deepness. If I add a 6mil plastic before wrapping them in fabric, do I need to do it only on the front of the panel? Or on the back too?



No only the front should be fine.


> Quote:
> Finally... My worst fear is to over treat my small room, which is 12 x 12.... So here is what I would have: 3 absorption panels ( 3 x 24 x48 ) on the back wall, 2 room corners with bass traps from ground to ceiling ( 2 panels 6 x 24 x48 in each corner) and 4 amovible absorption panels on stands( same than those on the back wall, 2 on each side at first reflection points ) ... I can't treat the 2 room remaining corners with bass traps, since they are in the kitchen ...living room and kitchen are the same room , rectangular... So the living room is open on the right side, no wall there...Would it become too dead sounding that way?



Plan looks fine but just to note you would get a much better sound if you faced the left wall. That would make everything symmetrical in your setup. The panels you have now on stands really are not doing much.


----------



## Aarghon

Thanks a lot Myfipie! ( Glenn Kuras in disguise? hehe) Your help is most helpful!


I'll see what I can do to space the panels from the wall a litle more!


For the wall on the left, It would definitely be better, but there is a sliding glass door there... Sadly, Not sure that humidity there wouldn't be a problem for my electronics, since I often get water condensation on the door at winter times...


I had the idea of putting a suspended track on the ceiling and put a heavy window drapery to seal the zone from the kitchen, and have a square listening area...( and minimize the sound bouncing back from nearby kitchen hardwood furniture...) Don't know if it would be a good idea though, the fabric would most likely need to be sound absorbent, and not reflective. right?


Again, thanks for the help!


Edit : not in disguise at all, it's indicated at the bottom of your post haha!


----------



## BrutaleZEN

Guys,


I am a newbie in acoustical treatment. I am living in Thailand where the choice for boards are really limited.

Can Roxul Rockboard 60 and Rockboard 80 be suitable for side panels and bass traps ? In which thickness ?


I am building my HT room and wants to know if I make the good choice with those boards.


Have a good day.


----------



## myfipie

"I had the idea of putting a suspended track on the ceiling and put a heavy window drapery to seal the zone from the kitchen, and have a square listening area...( and minimize the sound bouncing back from nearby kitchen hardwood furniture...) Don't know if it would be a good idea though, the fabric would most likely need to be sound absorbent, and not reflective. right?"


All you would end up doing is over absorbing the upper energy in the room and leaving the low end sounding muddy. I personally would not do that. Put a few panels in the kitchen area if you seem to get reflections from there. I would try it without first.

How low end reacts in a room:
http://www.gikacoustics.com/video_bass-traps/


----------



## myfipie




> Quote:
> Originally Posted by *BrutaleZEN*  /t/255432/acoustical-treatments-master-thread/9930#post_24275867
> 
> 
> Guys,
> 
> 
> I am a newbie in acoustical treatment. I am living in Thailand where the choice for boards are really limited.
> 
> Can Roxul Rockboard 60 and Rockboard 80 be suitable for side panels and bass traps ? In which thickness ?
> 
> 
> I am building my HT room and wants to know if I make the good choice with those boards.
> 
> 
> Have a good day.



Basically yes either is fine. I would make them no less then 4" thick and straddle as many corners as possible. You can use the following as a guide for set up of acoustics.
http://www.gikacoustics.com/the-basics-bass-traps-diffusion-panels/


----------



## BrutaleZEN

Thanks Glenn,


that is a quick answer to my small problem !!! I will go for it.


Have a good day.


----------



## Aarghon

Ok, I won't even try the curtain, your answer seems pretty logical!


And by the way, thanks mr. Kuras for the help. I am amazed to see how much you are truly passionate about audio. You sell panels, and a lot of people wouldn't help people to build their own because of that... They would think : "every time I help someone, it's a potential customer that goes away ". You care to help people only asking, so I can easily see how much you take good care of your customers!


Same applies to Mr Winer. The world needs more people like you, good sirs.


----------



## Glenn Baumann




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/9930#post_24279142
> 
> 
> Ok, I won't even try the curtain, your answer seems pretty logical!
> 
> 
> And by the way, thanks mr. Kuras for the help. I am amazed to see how much you are truly passionate about audio. You sell panels, and a lot of people wouldn't help people to build their own because of that... They would think : "every time I help someone, it's a potential customer that goes away ". You care to help people only asking, so I can easily see how much you take good care of your customers!
> 
> 
> Same applies to Mr Winer. The world needs more people like you, good sirs.




^^^


"The world needs more people like you, good sirs."


...AMEN!











Glenn


----------



## robc1976




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/9930#post_24279142
> 
> 
> Ok, I won't even try the curtain, your answer seems pretty logical!
> 
> 
> And by the way, thanks mr. Kuras for the help. I am amazed to see how much you are truly passionate about audio. You sell panels, and a lot of people wouldn't help people to build their own because of that... They would think : "every time I help someone, it's a potential customer that goes away ". You care to help people only asking, so I can easily see how much you take good care of your customers!
> 
> 
> Same applies to Mr Winer. The world needs more people like you, good sirs.


agreed, my entire room is treated by GIK and it has been awesome working with them..there customer service is 2nd to none.


----------



## myfipie




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/9930#post_24279142
> 
> 
> Ok, I won't even try the curtain, your answer seems pretty logical!
> 
> 
> And by the way, thanks mr. Kuras for the help. I am amazed to see how much you are truly passionate about audio. You sell panels, and a lot of people wouldn't help people to build their own because of that... They would think : "every time I help someone, it's a potential customer that goes away ". You care to help people only asking, so I can easily see how much you take good care of your customers!
> 
> 
> Same applies to Mr Winer. The world needs more people like you, good sirs.



Well thanks. I really do not see it as taking about business but just helping to spread the word. The more people understand acoustics and treating there rooms the better, IMO.










> Quote:
> there customer service is 2nd to none.



I am pretty damn proud of my team. They take a lot of pride in there work.


----------



## teevman

Hi all.







Great thread with lots and lots of very useful info!


Have a quick question. I'm in a new house with a fairly large living area (27' x 21' x 12' cathedral) with echos a plenty.










We are starting to add more and more stuff to the room which has helped some but still nothing on the walls. We have some canvas art prints coming and that should help with reflections (fingers crossed).


They will be in 1.5" thick frames so thought I would add some sound absorbing material to the backs of them. Which would be better, the lighter roxul "safe and sound" or denser roxul "comfortboard" similar to the 8 pcf rockboard. I'm in Canada and the 8pcf comfortboard is all that I can find. Thanks for any help.


----------



## myfipie




> Quote:
> They will be in 1.5" thick frames so thought I would add some sound absorbing material to the backs of them.



That really is not going to help much. The canvas used for painting is pretty thick, and will most likely reflect at about the same low frequency 1.5" of fiberglass will absorb. Netting about zero help from the fiberglass.

For art on panels you really need to use a process called dye-sublimation that dye the image into the fabric that is more open weaved. You can do a search for getting it done DIY but here is our product so you can understand the process.
http://www.gikacoustics.com/product/gik-artpanel-acoustic-panels/


----------



## nickbuol

For DIY information on "printed" fabric for panels, check out the thread DIY Custom-Printed Movie Poster Acoustic Panels-cheap! Jump to the end of the thread and ask your questions. The fabric used at the beginning of that thread is not longer the best option, but to keep this thread on track, I just say to jump over there or check out GIK's stuff if you don't want to DIY...


----------



## teevman

If one was to use roxul safe and sound batt insulation in a panel can you use cardboard on the back to keep it contained. Thanks


----------



## HopefulFred

Yes.


In some cases, particularly if the backing is spaced away from the wall, you can have resonant absorption going on - which may or may not be helpful.


----------



## teevman




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9930#post_24292730
> 
> 
> Yes.
> 
> 
> In some cases, particularly if the backing is spaced away from the wall, you can have resonant absorption going on - which may or may not be helpful.



Thanks.


Do you have any idea if using the roxul safe and sound batt's and compressing them then backing with cardboard to keep it compressed would make it perform closer to the roxul rockboard 60/80? Can't seem to easily locate any of the rockboard and also the safe and sound is a lot cheaper. By the way i'm limited to 2" in my panels. Logic tells me that rockboard is basically just compressed safe and sound but maybe it isn't. Thanks again.


----------



## MuaySteve




> Quote:
> Originally Posted by *teevman*  /t/255432/acoustical-treatments-master-thread/9930#post_24292983
> 
> 
> Thanks.
> 
> 
> Do you have any idea if using the roxul safe and sound batt's and compressing them then backing with cardboard to keep it compressed would make it perform closer to the roxul rockboard 60/80? Can't seem to easily locate any of the rockboard and also the safe and sound is a lot cheaper. By the way i'm limited to 2" in my panels. Logic tells me that rockboard is basically just compressed safe and sound but maybe it isn't. Thanks again.



Hey Teevman... There are a few of us who have used the Roxul Comfort board IS panels as that is all we can easily find up here in Canada. It is a much heavier and denser product, and more like OC703 then safe and sound is. It is an inch and half think and makes good panels. You can find a couple examples over on the DIY Custom-Printed Movie Poster Acoustic Panels-cheap! thread.


Hope this helps.


Steve


----------



## nvidio




> Quote:
> Originally Posted by *teevman*  /t/255432/acoustical-treatments-master-thread/9930#post_24292983
> 
> 
> Thanks.
> 
> 
> Do you have any idea if using the roxul safe and sound batt's and compressing them then backing with cardboard to keep it compressed would make it perform closer to the roxul rockboard 60/80? Can't seem to easily locate any of the rockboard and also the safe and sound is a lot cheaper. By the way i'm limited to 2" in my panels. Logic tells me that rockboard is basically just compressed safe and sound but maybe it isn't. Thanks again.


I would go with the 3.0 pcf Knauf Black Acoustical Board.

http://www.knaufinsulation.ca/en/content/black-acoustical-board 


It doesn't contain toxic formaldehyde, it doesn't smell bad unlike Roxul Safe'n'Sound, and it also compares pretty well to other 2" thick insulation materials:

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## teevman




> Quote:
> Originally Posted by *MuaySteve*  /t/255432/acoustical-treatments-master-thread/9930#post_24293559
> 
> 
> Hey Teevman... There are a few of us who have used the Roxul Comfort board IS panels as that is all we can easily find up here in Canada. It is a much heavier and denser product, and more like OC703 then safe and sound is. It is an inch and half think and makes good panels. You can find a couple examples over on the DIY Custom-Printed Movie Poster Acoustic Panels-cheap! thread.
> 
> 
> Hope this helps.
> 
> 
> Steve



Hey another canuck, i'm in Alberta!


Yes I see the 1.5" comfortboard at homedepot . I was hoping to squeeze 2" into my art panels but this will likly be close enough. Thanks.


----------



## MuaySteve

It has worked out pretty well for me. I can tell you there is no odour or dust or anything from the material and that a 2' x 3' panel is about 12lbs.


I hung mine with french cleats so I could distribute the weight across a couple drywall anchors for each panel. It also allowed for a 3/4 inch gap between the panel and the wall.


Good Luck.


----------



## teevman

Are you sure they weight THAT much







I checked out a bundle on homedepot.ca and it says 6 panels in bundle and 40lbs. That would work out to around 6lbs. a panel.

http://www.homedepot.ca/product/roxul-r6-comfortboard-is-insulated-sheathing-board-for-basement-and-exterio/995375


----------



## Aarghon

Teevman: why are you limited to 2 inches?


I'm in Canada too... If you can go up to 3 inches, roxul safe'n'sound panels can be had for a mere 40$ for 8 panels... dimensions 24x12x3....


And 2 inches , from what I,ve read, seems a little limit for decent absorption... Maybe some more seasoned people here could correct me , though.


----------



## Aarghon

And I'm correcting myself already. Didn't see the question about comfort batt being better than safe'n'sound. I honestly don't know, but my safe.n.sound panels seems to do the job pretty well!


----------



## nvidio




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/9960#post_24295395
> 
> 
> Teevman: why are you limited to 2 inches?
> 
> 
> I'm in Canada too... If you can go up to 3 inches, roxul safe'n'sound panels can be had for a mere 40$ for 8 panels... dimensions 24x12x3....
> 
> 
> And 2 inches , from what I,ve read, seems a little limit for decent absorption... Maybe some more seasoned people here could correct me , though.


4" is the minimum, but you can get away with leaving a 2" air gap behind a 2" thick panel. If you can fill the air gap with additional insulation or if you can add a layer of sculpted foam to the back of the panel to make it thicker, that would be an improvement, but a 3" air gap behind a 3" panel would be even better.

http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/823721-thikcness-wall-panels.html


----------



## mtbdudex

Visual on porous absorber air gap rationale


----------



## MuaySteve




> Quote:
> Originally Posted by *teevman*  /t/255432/acoustical-treatments-master-thread/9930#post_24295012
> 
> 
> Are you sure they weight THAT much
> 
> 
> 
> 
> 
> 
> 
> I checked out a bundle on homedepot.ca and it says 6 panels in bundle and 40lbs. That would work out to around 6lbs. a panel.
> 
> http://www.homedepot.ca/product/roxul-r6-comfortboard-is-insulated-sheathing-board-for-basement-and-exterio/995375



I weighed one on my bathroom scale with me subtracting my weight form it... it was around 12 lbs... that's with the 3/4" pine frame, and the covering material, backing material and staples.... so say, even round it down to 10 lbs. I'll try it again later.


----------



## logicators

All,


I am considering to build bass traps for the corners and acoustic panels for side and back wall and have some newbie questions. Any help is highly appreciated:


1) I am considering to build bass traps using these 4", 4 pound dense Roxul Mineralwool panels:

http://www.buyinsulationproductstore.com/servlet/the-326/4%22-Roxul-Mineralwool-Bass/Detail 


The have an absorption co-efficient of 1.03 at 125 Hz (and an overall NRC of 1.1). I am unable to find data on frequencies lower than that. Any ideas how will they perform at lower frequencies? What if I use 2 to make a 8" deep bass trap? Or even 3 to make a 12" deep bass trap? At what point do we hit the law of diminishing returns?


2) Two of these traps will be in the corner and the other two will be close to the corner on side walls but not in the corner because of existing stuff which can't be moved. Should I worry about adding some air gap behind the ones that will not be placed in the corner?


3) For acoustic panels for side walls, should I use these 4" boards or the 2" ones which are cheaper but only work for high frequencies. Also, how important is adding the air gap?


4) Which of the following would you recommend to cover the front and sides of acoustic panels (black velvet or acoustically transparent speaker grill cloth)? The room (including the ceiling) is painted flat black, and I have used black GOM FR701 to cover the screen wall.

http://www.syfabrics.com/View.aspx/search/Black-Velvet-Suede-Cloth/828/0 

http://www.parts-express.com/speaker-grill-cloth-black-yard-70-wide--260-335 


5) I am considering to cover the back of the panels with construction paper. Would any of these work?

http://www.homedepot.com/p/Fortifiber-500-sq-ft-AQUABAR-B-Tile-Underlayment-Roll-70-195/202592567 

http://www.homedepot.com/p/Trimaco-35-in-x-140-ft-Brown-Builder-s-Paper-35140/202040749 


6) My ceiling is a drop ceiling with 2 x 4 tiles. Would you recommend replacing a few of the tiles with these 4" panels?


Thanks in advance for all your help!


----------



## cgott42

Wow - 333 pages. Is there any thread showing the current consensus (or close to it).

I have a 6'6" high ceiling, and 20.5x 13.3 room

I currently have 6 2x4 GIK 244 panels that I have along the side, rear, and adjacent to the front speakers in (hopefully) first reflection points and super plush carpeting. However, I want to (a) build the acoustic treatment into the room design (also change the colors) and (b) improve/complete the acoustic treatments. What should I do?


----------



## nickbuol




> Quote:
> Originally Posted by *cgott42*  /t/255432/acoustical-treatments-master-thread/9960#post_24321529
> 
> 
> Wow - 333 pages. Is there any thread showing the current consensus (or close to it).



Consensus of what? Every room is different from size, shape, construction, coverings, furniture, equipment, lighting, everything is different so there is no "one size fits all" solution. Boy, do I wish there was though.


> Quote:
> Originally Posted by *cgott42*  /t/255432/acoustical-treatments-master-thread/9960#post_24321529
> 
> 
> What should I do?



What are you trying to accomplish? Is the bass muddy? Dialog unclear? Tell the problem, and people can offer suggestions for your needs, but it can get complicated VERY quickly.


There are some general things that people recommend, like bass traps in as many corners as possible, panels (clouds) on the ceiling for first reflections, don't do just absorption, add diffusion too. Some say to treat the entire front wall behind the speakers, again getting into much more is going to require understanding the problem before a solution can be devised.


----------



## cgott42




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/9960#post_24321806
> 
> 
> Consensus of what? Every room is different from size, shape, construction, coverings, furniture, equipment, lighting, everything is different so there is no "one size fits all" solution. Boy, do I wish there was though.
> 
> What are you trying to accomplish? Is the bass muddy? Dialog unclear? Tell the problem, and people can offer suggestions for your needs, but it can get complicated VERY quickly.
> 
> 
> There are some general things that people recommend, like bass traps in as many corners as possible, panels (clouds) on the ceiling for first reflections, don't do just absorption, add diffusion too. Some say to treat the entire front wall behind the speakers, again getting into much more is going to require understanding the problem before a solution can be devised.



No problem that I'm trying to fix, rather building a room , and would like to build the acoustic treatments in the walls - and want to know what to do


----------



## Nick in Manitou

It has been a while since I have been involved on this site, but I believe that there are a couple folks with solid credentials who give discounted services to folks from the forum. The customer gives them the basics of the room shape and construction a gets an engineered plan for the appropriate acoustic treatment for that specific room.


It is a good service for those of us who want a good result without wanting to get a degree in acoustics ourselves. If you consider the time it would take to read (and really understand) all 300+ pages of this discussion...it is probably money well spent!


----------



## BasementBob




> Quote:
> Originally Posted by *logicators*  /t/255432/acoustical-treatments-master-thread/9960#post_24320007
> 
> 
> The have an absorption co-efficient of 1.03 at 125 Hz (and an overall NRC of 1.1). I am unable to find data on frequencies lower than that.



The standard reverberation room test ASTM C423 only goes down to 125 hz, so that's why you don't see test results lower than that.

Sometimes you will see results lower, but they're less official, and get less accurate the lower they go.


> Quote:
> Originally Posted by *logicators*  /t/255432/acoustical-treatments-master-thread/9960#post_24320007
> 
> 
> Any ideas how will they perform at lower frequencies?


Theoretically speaking, it's something like this













> Quote:
> Originally Posted by *logicators*  /t/255432/acoustical-treatments-master-thread/9960#post_24320007
> 
> 
> What if I use 2 to make a 8" deep bass trap? Or even 3 to make a 12" deep bass trap? At what point do we hit the law of diminishing returns?


NASA has a couple of wool based absorbers (rockwool) that are over 12 feet deep -- trying to quiet one of their supersonic wind tunnels if I remember correctly.

I was about to write that no one at AVS has ever put more than a few feet deep, but I seem to recall someone recently at AVS having a 5' deep absorber to get rid of a room mode, and it measured just fine (room mode gone).


Philip Newell is a fan of "non environment rooms", for recording control rooms, and I believe they have several feet of absorbers on 4 sides (ceiling, rear wall, left wall, right wall) with front wall and floor reflective. But your home theatre will lack 'spaciousness' if you do anything like that.


Since human beings are not very good at localizing sound direction from above, some people like having a ceiling first reflection point that's reflective. And most just have a drywall ceiling cause that's what they put there, rather than for an acoustic purpose.


Here's a foot deep absorber, that effectively wiped out a wall first reflection imaging problem (left speaker off right wall into right ear -- before absorber effect: the Star Wars pod race scene had bad imaging, and things that on the screen were on the left sounded like they were on the right).
http://www.bobgolds.com/Absorber/home.htm


----------



## logicators

Thank you!


----------



## nvidio




> Quote:
> Originally Posted by *logicators*  /t/255432/acoustical-treatments-master-thread/9960#post_24320007
> 
> 
> All,
> 
> 
> I am considering to build bass traps for the corners and acoustic panels for side and back wall and have some newbie questions. Any help is highly appreciated:
> 
> 
> 1) I am considering to build bass traps using these 4", 4 pound dense Roxul Mineralwool panels:
> 
> http://www.buyinsulationproductstore.com/servlet/the-326/4%22-Roxul-Mineralwool-Bass/Detail
> 
> 
> The have an absorption co-efficient of 1.03 at 125 Hz (and an overall NRC of 1.1). I am unable to find data on frequencies lower than that. Any ideas how will they perform at lower frequencies? What if I use 2 to make a 8" deep bass trap? Or even 3 to make a 12" deep bass trap? At what point do we hit the law of diminishing returns?
> 
> 
> 2) Two of these traps will be in the corner and the other two will be close to the corner on side walls but not in the corner because of existing stuff which can't be moved. Should I worry about adding some air gap behind the ones that will not be placed in the corner?
> 
> 
> 3) For acoustic panels for side walls, should I use these 4" boards or the 2" ones which are cheaper but only work for high frequencies. Also, how important is adding the air gap?
> 
> 
> 4) Which of the following would you recommend to cover the front and sides of acoustic panels (black velvet or acoustically transparent speaker grill cloth)? The room (including the ceiling) is painted flat black, and I have used black GOM FR701 to cover the screen wall.
> 
> http://www.syfabrics.com/View.aspx/search/Black-Velvet-Suede-Cloth/828/0
> 
> http://www.parts-express.com/speaker-grill-cloth-black-yard-70-wide--260-335
> 
> 
> 5) I am considering to cover the back of the panels with construction paper. Would any of these work?
> 
> http://www.homedepot.com/p/Fortifiber-500-sq-ft-AQUABAR-B-Tile-Underlayment-Roll-70-195/202592567
> 
> http://www.homedepot.com/p/Trimaco-35-in-x-140-ft-Brown-Builder-s-Paper-35140/202040749
> 
> 
> 6) My ceiling is a drop ceiling with 2 x 4 tiles. Would you recommend replacing a few of the tiles with these 4" panels?
> 
> 
> Thanks in advance for all your help!


1) Porous Absorber Calculator is your friend.


2) The reason why corners are the best place for bass traps is because the three axial modes of the room meet there. A room has 12 corners; treating as many of them as possible with bass traps gives the best bass trapping performance for the buck.


3) As per my previous reply to this thread, 4" is the minimum. I would go for a 4" air gap behind a 4" thick panel.


4) Hold the cloth close to your mouth while holding your hand behind the cloth. If you can feel that your breath passes through the cloth, that means it'll work just fine.


5) If leaving no air gap behind the panel, adding the paper to the back of the panel won't affect performance. If leaving an air gap, I would cover the back of the panel with the cheapest breatheable cloth I could find, but fluffy polyester batting or polyester fleece plaid or sculpted acoustic foam that you can't use for anything else also works well for this purpose.


6) Yes, panel absorbers can be used to treat the first reflection points on the ceiling.


----------



## artur9




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9960#post_24330840
> 
> 
> If leaving an air gap, I would cover the back of the panel with the cheapest breatheable cloth I could find.



The cheapest cloth I could find was landscape fabric. Anyone ever used that? It's like 10 bux for 50 yards.


----------



## Zen Traveler




> Quote:
> Originally Posted by *Zen Traveler*  /t/255432/acoustical-treatments-master-thread/5910#post_18195662
> 
> http://www.realtraps.com/products.htm



Fwiw, I came across this thread and don't remember this recommendation because I have no opinion on this matter....IOW, I can't imagine I would have provide this link.


----------



## nvidio




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9960#post_24331812
> 
> 
> The cheapest cloth I could find was landscape fabric. Anyone ever used that? It's like 10 bux for 50 yards.


I am not familiar with that. Most people use either burlap or muslin fabric. Burlap burns much easier than muslin does, so muslin provides better fire safety. Muslin is also easy to get at discount prices from Joann's Fabrics Online.


----------



## rabindu

We're building a new house, and I have the good fortune of being "allowed" a 24x18x12 media/family room. I'm planning to go the distance building a room within a room with hat channel/green glue/DD/ separate HVAC run. The problem is, along the perimeter wall, my wife wants windows! Not big windows, but she insists on some natural light. How am I going to accomplish a high STC rating if I have 2-3 gaping holes in all my hard work? I've tried researching all over the net, but I can't seem to find anything that isn't about blocking sound out. I'm not concerned about outside noise coming in. I want to prevent the theater noise from getiing to the rest of the house. Is this a solvable problem? Thanks, in advance, for any advice.


----------



## rabindu

Oops, wrong thread. Sorry about that.


----------



## mtbdudex

We all make mistakes, simply delete your 2 posts, I'll delete this one



Via my iPhone 5s & Tapatalk, LLAP


----------



## Skylinestar

Can I put my subwoofer (Rythmik FV15HP) behind a velvet curtain? Will the velvet affect the bass?


----------



## HopefulFred

Go ahead - no harm.


----------



## artur9




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9960#post_24332593
> 
> 
> I am not familiar with that. Most people use either burlap or muslin fabric. Burlap burns much easier than muslin does, so muslin provides better fire safety. Muslin is also easy to get at discount prices from Joann's Fabrics Online.



Yeah, the non-fireworthiness of burlap bothers me. Maybe I'll try muslin as it appears to only be about 1c more expensive per sq ft than landscape fabric.


----------



## artur9

For LF absorption does it work to put pink fluffy in lightweight plastic bags in large quantities?


I am trying to target LF below 60Hz.


I'm thinking I could put bags of pink fluffy behind acoustic panels made of 3" SafeNSound at either the corners or the wall/floor corner behind the listening position.


----------



## logicators

So what is the cheapest black fire resistant cloth for the front of the acoustic panels people use around here? I have used GOM FR701 for the screen wall but it's expensive. It seems like Velvet is a no-go because it's not acoustically transparent. Is speaker cloth from parts express or Joann Fabrics a good choice? Is it fire resistant?


----------



## mikela




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9960#post_24337071
> 
> 
> For LF absorption does it work to put pink fluffy in lightweight plastic bags in large quantities?
> 
> 
> I am trying to target LF below 60Hz.
> 
> 
> I'm thinking I could put bags of pink fluffy behind acoustic panels made of 3" SafeNSound at either the corners or the wall/floor corner behind the listening position.



I am planning on doing the same thing that Nils has done http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12#post_24127058 for my SBA. I am also planning on some type of diffusor in front of it.


Mike


----------



## nvidio




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9960#post_24337071
> 
> 
> For LF absorption does it work to put pink fluffy in lightweight plastic bags in large quantities?
> 
> 
> I am trying to target LF below 60Hz.
> 
> 
> I'm thinking I could put bags of pink fluffy behind acoustic panels made of 3" SafeNSound at either the corners or the wall/floor corner behind the listening position.


I wouldn't put plastic inside a bass trap TBH, but filling up a corner with pink fluffy Owens Corning fiberglass behind a layer of (relatively) rigid insulation such as Roxul Safe'n'Sound mineral wool does work quite spectacularly well if you want to build your own big (32" wide at the front, or even bigger) "Supertips SuperChunks"-style corner bass traps. For bass traps that are this big, the lower Gas Flow Resistivity of pink fluffy is what makes pink fluffy an actually even better choice than a pile of triangular slabs of Roxul Safe'n'Sound, both performance wise and pricewise.


----------



## artur9




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9960#post_24338201
> 
> 
> I wouldn't put plastic inside a bass trap TBH, but filling up a corner with pink fluffy Owens Corning fiberglass behind a layer of (relatively) rigid insulation such as Roxul Safe'n'Sound mineral wool does work quite spectacularly well if you want to build your own big (32" wide at the front, or even bigger) "Supertips SuperChunks"-style corner bass traps. For bass traps that are this big, the lower Gas Flow Resistivity of pink fluffy is what makes pink fluffy an actually even better choice than a pile of triangular slabs of Roxul Safe'n'Sound, both performance wise and pricewise.



Doesn't the pink fluffy need to be contained in something lest the fibers roam free?


What I was thinking was in making panels out of SafeNSound, putting them across the corner, then filling the space behind with pink fluffy. But it needs to be movable. Hence just tossing some bags in the space.


----------



## nvidio




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9960#post_24338828
> 
> 
> Doesn't the pink fluffy need to be contained in something lest the fibers roam free?
> 
> 
> What I was thinking was in making panels out of SafeNSound, putting them across the corner, then filling the space behind with pink fluffy. But it needs to be movable. Hence just tossing some bags in the space.


No, the sound will partly bounce off of the bags if you just toss them in the space behind the Safe'n'Sound. You could use just the Safe'n'Sound boards plus the wooden frame that keeps them in place to keep the pink fluffy from escaping via the front of the bass traps, and, to also keep it from escaping via their sides, add more woodwork and cover the sides in plywood or plastic foil combined with chicken wire netting or something like that. Since portable also implies having limited weight, IMO you should perhaps go for multiple bass traps that can be stacked vertically / hung above eachother. To keep the pink fluffy from compressing under its own weight, you might also want to tighten one or two vertically spaced, triangular pieces of wire netting inside each bass trap as supports.


----------



## mikela

The low frequencies you are targeting will not bounce off of a plastic bag.


----------



## NicksHitachi




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/9960#post_24331812
> 
> 
> 
> 
> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9960#post_24330840
> 
> 
> If leaving an air gap, I would cover the back of the panel with the cheapest breatheable cloth I could find.
> 
> 
> 
> 
> The cheapest cloth I could find was landscape fabric. Anyone ever used that? It's like 10 bux for 50 yards.
Click to expand...


I used this stuff and it works great for a backing material. You can breath through it and its strong enough to be pulled very taught. Also very professional looking for a backing IMO.


----------



## logicators




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9960#post_24330840
> 
> 
> 1) Porous Absorber Calculator is your friend.
> 
> 
> 2) The reason why corners are the best place for bass traps is because the three axial modes of the room meet there. A room has 12 corners; treating as many of them as possible with bass traps gives the best bass trapping performance for the buck.
> 
> 
> 3) As per my previous reply to this thread, 4" is the minimum. I would go for a 4" air gap behind a 4" thick panel.
> 
> 
> 4) Hold the cloth close to your mouth while holding your hand behind the cloth. If you can feel that your breath passes through the cloth, that means it'll work just fine.
> 
> 
> 5) If leaving no air gap behind the panel, adding the paper to the back of the panel won't affect performance. If leaving an air gap, I would cover the back of the panel with the cheapest breatheable cloth I could find, but fluffy polyester batting or polyester fleece plaid or sculpted acoustic foam that you can't use for anything else also works well for this purpose.
> 
> 
> 6) Yes, panel absorbers can be used to treat the first reflection points on the ceiling.



Thank you!


----------



## nvidio




> Quote:
> Originally Posted by *mikela*  /t/255432/acoustical-treatments-master-thread/9960#post_24340709
> 
> 
> The low frequencies you are targeting will not bounce off of a plastic bag.


That is correct, but if they are just tossed in the space behind the Safe'n'Sound, the plastic bags will compress the pink fluffy insulation that's inside them, and that is what will cause them to partly reflect the sound.. even at frequencies below 60 Hz. So if you are targeting 60 Hz and below, not only do you want to make the bass traps very thick, but you also really want to keep that Gas Flow Resistivity low enough or you will still lose performance, and, thicker you decide to make the bass traps, lower the optimum Gas Flow Resistivity.


----------



## mikela




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9990#post_24343315
> 
> 
> That is correct, but if they are just tossed in the space behind the Safe'n'Sound, the plastic bags will compress the pink fluffy insulation that's inside them, and that is what will cause them to partly reflect the sound.. even at frequencies below 60 Hz. So if you are targeting 60 Hz and below, not only do you want to make the bass traps very thick, but you also really want to keep that Gas Flow Resistivity low enough or you will still lose performance, and, thicker you decide to make the bass traps, lower the optimum Gas Flow Resistivity.



The measurements that Nils took seem to indicate otherwise http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12#post_24127058 . He is using baled rockwool to great effect. It will, however, reflect higher frequencies. I think they operate a little bit like small tube traps.


----------



## nvidio




> Quote:
> Originally Posted by *mikela*  /t/255432/acoustical-treatments-master-thread/9990#post_24343356
> 
> 
> The measurements that Nils took seem to indicate otherwise http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12#post_24127058 . He is using baled rockwool to great effect.


I followed the link you posted, but I did not find any measurements that could indicate what you said. It seems to me it is more about using multiple subwoofers to achieve active cancellation of room modes than it is about the relationship between the thickness of porous corner bass absorbers and Gas Flow Resistivity of the absorbent material used in them.


----------



## mikela

It it the decay chart in the post I linked that shows how effective it is.


----------



## nvidio




> Quote:
> Originally Posted by *mikela*  /t/255432/acoustical-treatments-master-thread/9990#post_24343710
> 
> 
> It it the decay chart in the post I linked that shows how effective it is.


I see. That bass trap isn't just very thick, it is absolutely humongously thick.. It is 55 cm with a 10 cm air gap behind it. I suppose if the plastic were removed from the back side of it, it would perform only slightly better due to the law of diminishing returns kicking in at this kind of thickness, due to the fact the plastic is at only 10 cm distance from the wall behind it, and due to the fact this type of insulation doesn't as easily compress under its own weight as pink fluffy Owens Corning fiberglass does. Also, thin plastic on the front face actually does improve the bass trapping performance (but also causes the higher frequencies to be reflected, like you already said). http://forums.musicplayer.com/ubbthreads.php/topics/2408649/Plastic_for_Bass_Traps 


By following the advice I gave, you could achieve similar bass trapping performance with less thick bass traps that would not only take up less space and weigh less, but also cost less.


----------



## nvidio

Here is a link that shows you don't want Gas Flow Resistivity much higher than 5000 Pa.s/m², which is quite common, for a bass trap if targeting below 60 Hz.


----------



## jbrown15

So without having to go thru this entire thread I have a quick question to ask the experts in regards to using acoustical panels. Which would I be better off going with, A) 4" thick panels or B) 2" thick panel with a 2" air space behind the panel?


Thanks in advance.


----------



## nvidio




> Quote:
> Originally Posted by *jbrown15*  /t/255432/acoustical-treatments-master-thread/9990#post_24345441
> 
> 
> So without having to go thru this entire thread I have a quick question to ask the experts in regards to using acoustical panels. Which would I be better off going with, A) 4" thick panels or B) 2" thick panel with a 2" air space behind the panel?
> 
> 
> Thanks in advance.


A)


----------



## nickbuol

True, but A and B aren't too far off. If someone already has the 2" material, adding an air gap behind it is a BIG boost *towards* being almost as good as 4"... 4" is still better though.


----------



## mikela




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9990#post_24344089
> 
> 
> By following the advice I gave, you could achieve similar bass trapping performance with less thick bass traps that would not only take up less space and weigh less, but also cost less.



I would probably agree on the cost, however, without measurements I am not so sure about performance. Do you think corner traps would measure the same or better for a planar bass wave? Here is the original thread on double bass arrays http://www.avsforum.com/t/837744/double-bass-array-dba-the-modern-bass-concept/240#post_24292118 . Nils data looks so good it almost looks like it was "dry labbed". He is operating in a concrete basement.


----------



## nvidio




> Quote:
> Originally Posted by *mikela*  /t/255432/acoustical-treatments-master-thread/9990#post_24345820
> 
> 
> I would probably agree on the cost, however, without measurements I am not so sure about performance.


There are several threads on Gearslutz forum about that. Here is an example. http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/871453-density-fiberglass-huge-bass-trap.html 


> Quote:
> Do you think corner traps would measure the same or better for a planar bass wave? Here is the original thread on double bass arrays http://www.avsforum.com/t/837744/double-bass-array-dba-the-modern-bass-concept/240#post_24292118 . Nils data looks so good it almost looks like it was "dry labbed". He is operating in a concrete basement.


I am not very familiar with the concept of bass arrays, but anyway, it just seems a bit overkill to me. On the subject of reducing seat-to-seat variations, Todd Welti has had more than reasonably good success using just 4 small subs that were strategically placed throughout the room and individually EQ'd, so.. why not stick to that, build some "normal" SuperChunks that are made out of something like 4 kPa.s/m² Knauf fiberglass (or if it's too hard to get, 5 kPa.s/m² of whatever) and then just sit back and relax!


----------



## FoLLgoTT




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9990#post_24347556
> 
> 
> I am not very familiar with the concept of bass arrays, but anyway, it just seems a bit overkill to me.



Overkill? It depends.










The number of drivers is not fixed. It can be 1 or 1000. It is freely scalable and the number only depend on wall size, desired SPL max and desired upper cut-off frequency.


> Quote:
> On the subject of reducing seat-to-seat variations, Todd Welti has had more than reasonably good success using just 4 small subs that were strategically placed throughout the room and individually EQ'd, so..



Welti's method results in different gains of the subwoofers which reduces SPL max . And I don't see that it gets a seat-to-seat variation near to what a DBA can deliver. Not even close to that. Unfortunately there are no decay measurements in this paper. So it is hard to compare this important parameter at which a DBA or heavily damped SBA really shines.


----------



## nvidio




> Quote:
> Originally Posted by *FoLLgoTT*  /t/255432/acoustical-treatments-master-thread/9990#post_24348502
> 
> 
> Overkill? It depends.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The number of drivers is not fixed. It can be 1 or 1000. It is freely scalable and the number only depend on wall size, desired SPL max and desired upper cut-off frequency.
> 
> Welti's method results in different gains of the subwoofers which reduces SPL max . And I don't see that it gets a seat-to-seat variation near to what a DBA can deliver. Not even close to that. Unfortunately there are no decay measurements in this paper. So it is hard to compare this important parameter at which a DBA or heavily damped SBA really shines.


See the conclusion on pages 27 and 28 in the document linked below..
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf


----------



## FoLLgoTT




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/9990#post_24352904
> 
> 
> See the conclusion on pages 27 and 28 in the document linked below..
> http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf



I know this paper.










The range of that graph is 100 dB! Everything looks good at 100 dB. But if you take a closer look you'll see that there are differences of nearly 30 dB from one seat to another. This is nothing to be proud of. A DBA is much better in this regard. Please take a look at my measurement at different positions . It was taken from 1 to 4 m distance to the front wall.


----------



## Nyal Mellor

I wrote a blog article about my implementation of a four subwoofer array in my demo room .


It's not really a straightforward four sub approach and not really a double bass array, something in between. The key for me was delaying and polarity inverting the rear subs to time align and cancel the length modes at the listening position (that's what gives it the similarities with the DBA approach).


----------



## sdurani




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/9990#post_24353427
> 
> 
> I wrote a blog article about my implementation of a four subwoofer array in my demo room .


Interesting, my room length is exactly the same as your's (16'8") and my seating ended up at 10' (only 4" from where you ended up). Some coincidence.


----------



## daONES1

Hi All,

I need help, I finished off my dedicated home theater a few months ago. My room which is 19 X 15 is in the basement so I covered all walls with a fabric. No acoustic properties, just some very nice looking fabric from the local textile warehouse. 3 walls are lined with fabric, carpet on the floor with the screen wall and ceiling painted black. I didn't think it would make much of a difference to the overall sound quality. There is no acoustic material behind the fabric just plain everyday drywall. My initial audio setup included: Niles Stagefront LCR 1870 speakers with Emotiva UMC-1 with UPA-5 channel amp. I could not get very clear sound from this setup. Especially in the range of voice. I have to turn up the sound quite a bit in order to hear all that the movie has too offer. So it must be the equipment right? Must be time for an upgrade. So that is what I did. I exchanged the Emotiva for an Onkyo 818 and the Niles for BIC Acoustic PL-89 series for the front 3 and Klipsch RB600 for surrounds. All horn speakers should help with the brightness of the sound and possibly the clarity. Different equipment same problem. Anyway, any suggestions on where I should start on adjusting room acoustics. I'm wide open to suggestions.


----------



## Niroe64

So I am about to start setting up my acoustic panels along my walls and had planned on just covering them with burlap for now. However, while shopping at the local fabric store a nice color of a felt fabric caught my eye. I tested it out by blowing through it and it was pretty transparent in that regard. Would the felt work as covering? I am not sure if the blow test is the only determining factor. Thanks a bunch!


----------



## Stumbo




> Quote:
> Originally Posted by *Niroe64*  /t/255432/acoustical-treatments-master-thread/9990#post_24361863
> 
> 
> So I am about to start setting up my acoustic panels along my walls and had planned on just covering them with burlap for now. However, while shopping at the local fabric store a nice color of a felt fabric caught my eye. I tested it out by blowing through it and it was pretty transparent in that regard. Would the felt work as covering? I am not sure if the blow test is the only determining factor. Thanks a bunch!



You will be just fine with that fabric!


----------



## nvidio




> Quote:
> Originally Posted by *daONES1*  /t/255432/acoustical-treatments-master-thread/9990#post_24361776
> 
> 
> Hi All,
> 
> I need help, I finished off my dedicated home theater a few months ago. My room which is 19 X 15 is in the basement so I covered all walls with a fabric. No acoustic properties, just some very nice looking fabric from the local textile warehouse. 3 walls are lined with fabric, carpet on the floor with the screen wall and ceiling painted black. I didn't think it would make much of a difference to the overall sound quality. There is no acoustic material behind the fabric just plain everyday drywall. My initial audio setup included: Niles Stagefront LCR 1870 speakers with Emotiva UMC-1 with UPA-5 channel amp. I could not get very clear sound from this setup. Especially in the range of voice. I have to turn up the sound quite a bit in order to hear all that the movie has too offer. So it must be the equipment right? Must be time for an upgrade. So that is what I did. I exchanged the Emotiva for an Onkyo 818 and the Niles for BIC Acoustic PL-89 series for the front 3 and Klipsch RB600 for surrounds. All horn speakers should help with the brightness of the sound and possibly the clarity. Different equipment same problem. Anyway, any suggestions on where I should start on adjusting room acoustics. I'm wide open to suggestions.


Here are some links. As you start to learn the basics of how to set up a room, you should also be able to follow various links on those pages to get more detailed info about acoustics and room treatments.

http://realtraps.com/art_room-setup.htm 

http://www.gikacoustics.com/acoustic-primer 

http://ethanwiner.com/acoustics.html 

http://www.gearslutz.com/board/studio-building-acoustics/610173-acoustics-treatment-reference-guide-look-here.html 

http://getbettersound.com


----------



## daONES1

Thanks for the response Nvidio. I will take a look.


----------



## localhost127




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/9960_60#post_24295978
> 
> 
> Visual on porous absorber air gap rationale



illustration doesn't factor in speed of sound change in porous absorber (vs that of air); thus, refraction.


----------



## toofast68


Good evening....

 

So without spending a fortune in some tuned bass traps...what other options to I have.

 

I already have LARGE full wall traps in the front corner of my room...been working on getting stuff tuned.  The sound is decent, have a bit of work on the super low end of course.  My room setup is in my tag...dedicated "open concept" room...hard to work with for sure...but it is what it is.

 

Any advice appreciated...


----------



## artur9




> Quote:
> Originally Posted by *toofast68*  /t/255432/acoustical-treatments-master-thread/9990#post_24372031
> 
> 
> Good evening....
> 
> Any advice appreciated...



Your graph doesn't conform to the format described in the guide. You're gonna get a lot of grief about that.


----------



## toofast68

Crude... sorry....will fix when I land.


Sent from my DROID RAZR HD using Tapatalk


----------



## artur9




> Quote:
> Originally Posted by *toofast68*  /t/255432/acoustical-treatments-master-thread/9990#post_24372449
> 
> 
> Crude... sorry....will fix when I land.



Actually, I apologize. I thought you had posted this in the REW thread where there *are* guideliness. This thread is a free for all


----------



## toofast68

But still I want to post something that's helpful I was playing with my settings and I must have screwed something up


Sent from my DROID RAZR HD using Tapatalk


----------



## brwsaw




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/9780#post_23958760
> 
> 
> Here you are http://www.blu-ray.com/community/gallery.php?member=wes&folderid=3141



I think your room cost more than my house...just saying...


----------



## Skylinestar

Do I need to maintain symmetry in bass trap placement? Can I place bass traps in 3 corners of my room, leaving the 4th corner, where the door is, empty? Or shall I just ignore the 3rd corner too to maintain symmetry?


----------



## wse




> Quote:
> Originally Posted by *brwsaw*  /t/255432/acoustical-treatments-master-thread/9990#post_24372682
> 
> 
> I think your room cost more than my house...just saying...



I don't think so


----------



## erkq




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10020#post_24373213
> 
> 
> I don't think so



Room AND equipment, then.


----------



## myfipie




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/9990#post_24373161
> 
> 
> Do I need to maintain symmetry in bass trap placement? Can I place bass traps in 3 corners of my room, leaving the 4th corner, where the door is, empty? Or shall I just ignore the 3rd corner too to maintain symmetry?



That depends if the corner is in the front of the room or the back. If the front (the wall you face when sitting) then you do what to keep things equal left and right. If the back of the room it is less important. .


----------



## brwsaw




> Quote:
> Originally Posted by *erkq*  /t/255432/acoustical-treatments-master-thread/10020#post_24373266
> 
> 
> Room AND equipment, then.



That is what I meant. Just looking at it, that is. I didn't price shop to confirm.

Looks nice, hope it sounds as good as it looks.


----------



## wse




> Quote:
> Originally Posted by *brwsaw*  /t/255432/acoustical-treatments-master-thread/10020#post_24374353
> 
> 
> That is what I meant. Just looking at it, that is. I didn't price shop to confirm.
> 
> Looks nice, hope it sounds as good as it looks.



Thanks it sound very good thanks


----------



## toofast68


Ok, so I fixed my waterfall...still have some ringing at 600 MS - explains a bit of what I hear.  Room is so ROUGH to work with, just not sure where to continue.

 

OR is this NOT TOO BAD for a "multi purpose" room and I can spend a whole more without massive improvements.

 

Once again, fully treated front wall and full corner traps on left / right front.  I have a two - tiered ceiling - basically a giant recessed ceiling.  My Setup has room details.


----------



## HopefulFred

Have you measured the noise floor to see what if any of that low frequency stuff might not be in your audio system? You could be seeing your heater blowing in that waterfall - or does it disappear after 600ms?


----------



## toofast68

Great question...not sure. I will dig into that....just learning all the rew stuff....


Sent from my DROID RAZR HD using Tapatalk


----------



## brwsaw

I'm looking at different option's for my corner traps.

I have lots of safe and sound left but I'm tempted to take it back and get 2" or perhaps 4" rigid fiberglass.

I'm curious to know if any benifit can come from layering different densities of rigid together. For example would solid 4" stacks be more or less beneficial vs a stack that alternates bewteen 1x4" piece and say 3x2" pieces continued in that pattern to the top?

Also thinking I might cut the 8" triangle off the back leaving an air gap. One of my rear corners will only fit an 8" wedge.

Both front would be 32"s? across and both rears 14"s? across.

Any help would be appreciated, I won't be doing much more in the acoustic treatment department, at least not right away, and it seems like a lot of trial and error/reading and rereading for what could (in theory) be completed in a day.


----------



## brwsaw

I just taped it out to confirm and it looks like I could use the 24" batts and cut out a 12x12x18 wedge from both traps which would leave 12" thick traps with 12" air gap behind.

I have no clue if this would be worthwhile but I like the idea.

I'd have to cut the 8x8x12 wedge too but I think it is a start.


----------



## myfipie




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/10020#post_24381446
> 
> 
> Have you measured the noise floor to see what if any of that low frequency stuff might not be in your audio system? You could be seeing your heater blowing in that waterfall - or does it disappear after 600ms?



Plus one. Trying to tame things below 40hz is not a easy task and a lot of times you can't even really hear it.


----------



## myfipie




> Quote:
> Originally Posted by *brwsaw*  /t/255432/acoustical-treatments-master-thread/10020#post_24382753
> 
> 
> I just taped it out to confirm and it looks like I could use the 24" batts and cut out a 12x12x18 wedge from both traps which would leave 12" thick traps with 12" air gap behind.
> 
> I have no clue if this would be worthwhile but I like the idea.
> 
> I'd have to cut the 8x8x12 wedge too but I think it is a start.



That really is to small. When filling the corner you want at minimum 24" on the face and 17" on the sides.

As far as what to use, when filling the corner or making them thick, the less dense fiberglass will work better.


----------



## toofast68




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10020#post_24384393
> 
> 
> 
> Plus one. Trying to tame things below 40hz is not a easy task and a lot of times you can't even really hear it.


 

 

Ok...sounding like I might be in better shape than I thought   Will figure out how to measure floor noise and report back.

 

Thanks again!


----------



## brwsaw




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10020#post_24384431
> 
> 
> That really is to small. When filling the corner you want at minimum 24" on the face and 17" on the sides.
> 
> As far as what to use, when filling the corner or making them thick, the less dense fiberglass will work better.



17" on the sides would mean using more of the batt...or cutting less off...hmm

I'd hate to waste $ on insulation but it needs to be tried and proven.

I have no way to take measurements atm so any perceived improvement will be good.

Curious, should I run YPAO before installing the batts, after or not at all and complete the manual configuration?


----------



## brwsaw




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10020#post_24384431
> 
> 
> That really is to small. When filling the corner you want at minimum 24" on the face and 17" on the sides.
> 
> As far as what to use, when filling the corner or making them thick, the less dense fiberglass will work better.



Assuming you mean the 8x8x12 corner stack? Its all that will fit because of the doorway and trim. I'd assume it would be better than none. If not I'll build 3 identical traps 24x24x36(x90) and call it a day.


----------



## myfipie




> Quote:
> Originally Posted by *brwsaw*  /t/255432/acoustical-treatments-master-thread/10020#post_24386485
> 
> 
> Assuming you mean the 8x8x12 corner stack? Its all that will fit because of the doorway and trim. I'd assume it would be better than none. If not I'll build 3 identical traps 24x24x36(x90) and call it a day.



It might help with some flutter or decay above 400hz or so but that is about it. Not a waist but then again not that much of a gain. Size matters.


----------



## brwsaw




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10020#post_24386606
> 
> 
> It might help with some flutter or decay above 400hz or so but that is about it. Not a waist but then again not that much of a gain. Size matters.



I can live with less flutter. The room had a bit of an echo when it was finished/ before there was any thing in it.

I will add absorption and diffusion to the side walls as I go.

The three large ones make sense though, for the difference in cost why not.

I noticed people leaving gaps between the walls and t traps, would 1" on the sides be enough?


----------



## blazar




> Quote:
> Originally Posted by *jasplat88*  /t/255432/acoustical-treatments-master-thread/150#post_4818425
> 
> 
> 
> Kras,
> 
> 
> 
> You may be correct, but I maintain that I still like the way my Def's sound even over other monopoles....so oh well.
> 
> 
> 
> The point I was making was......in general, the front wall of a HT should be acoustically treated. Period!



The big def techs have a very involving and fun sound they produce. A lot of fun and reasonably priced for their performance. If you have the opportunity, I would also suggest a listen to planar or spherical horn speakers which also have a very "exciting" presentation. Great ribbon speakers can also sound very beautiful.


----------



## yngdiego

I'm moving to a new house, and will have to re-setup my home theater. Currently I have bass traps in three corners (fiber glass triangles), and rectangular fiber glass panels on the sides, front, and ceiling. I did this back in 2008 and there was a free program that let me input speaker location and viewer location, and it came back with recommended acoustical treatment locations.


Anyone know of a similar program with a current download link?


My new home theater will still be on the cozy size at 12 x 14 x 9' ceilings. But I'm looking forward to getting it fairly well treated like my existing 10x10x8 room.


----------



## Niroe64

You should just have to run a mirror along the walls at ear level, with someone pointing a laser pointer at it from ear level while sitting at the Main listening position and any other seating that is important. Wherever the laser lands centered on the speakers is where you want to place a panel, with the center of the panel at ear level as well.


There should be at least two on each side wall. The furthest forward panel should be for the speaker closest to that wall while the panel closer to the seating area should be for the front on the other side of the room. For the ceiling just place some panels halfway between the seating position and the front speakers.


Wherever there are large open and parallel surfaces try placing some treatment, trying to keep it somewhat symmetrical ( don't put 10 panels on the left wall but only 2 on the right)


I apologize if this was not what you were looking for and must admit I have a minimal amount of knowledge about this subject. What I do know has been learned by scouring this forum and applied in my own room without any formal measurements but with very positive results.


If it didn't help at all then hopefully it will help any lurkers out there unsure of where to start. This thread is a beast to get through!


----------



## Nightlord

If the rooms is rectangular, you can try my app, you can get it from here. No manual, hope it's reasonably self explanatory. Meter system based, though.

http://www.nattlorden.com/software/software.html


----------



## Frank D




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/10020#post_24455272
> 
> 
> If the rooms is rectangular, you can try my app, you can get it from here. No manual, hope it's reasonably self explanatory. Meter system based, though.
> 
> http://www.nattlorden.com/software/software.html



Great app and very easy to use.


Thank you.


----------



## Nightlord




> Quote:
> Originally Posted by *Frank D*  /t/255432/acoustical-treatments-master-thread/10020#post_24455685
> 
> 
> Great app and very easy to use.
> 
> 
> Thank you.



Thanks.


Did it for myself only, really, but if anyone else has use for it, it just makes me happy.










Haven't done anything to it in a long while, guess I'd really like to make it handle non-rectangular rooms too, but that needs a fundamental re-write unfortunately and I don't have a personal need for that to push me on. I do have anexperimental version for it to find locations for multiple surrounds which I've shown screendumps of on some occassions, so I guess that's the likeliest futute development direction for it, actually.


----------



## bigbadbob

Anybody every use this company or use this brand? Curious if you would recommend

www.foambymail.com/CBA/corner-bass-absorbers.html


----------



## BIGmouthinDC

Google Ethan Winer and Foam by mail

http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/347215-foam-factory-foam-mail-dilemma.html


----------



## myfipie




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10020#post_24484633
> 
> 
> Google Ethan Winer and Foam by mail
> 
> http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/347215-foam-factory-foam-mail-dilemma.html



Actually did a test with that foam myself. See the following results.
http://www.gikacoustics.com/comparing-foam-to-gik-244-bass-traps/


----------



## bigbadbob

Weill there you have it. If its too good to be true... It probably is.


----------



## thestoneman

Anybody care to chime in? I attached a very basic layout of my open media room. I want to get the best sounding room I can without bursting the bank. I'm freaking out about the room being open and what acoustical abnormalities this will cause. Especially with having a bar and a tile floor in the back.


Any thoughts on what I need to do to ensure the best results? Will the in wall treatments I am planning (Roxul SafenSound, RSIC clips, etc) positively affect the sound IN the room?


----------



## wse

Just created a bass trap using cotton absorbing panels 24" x 48" x 8" it really helped


----------



## nickbuol




> Quote:
> Originally Posted by *thestoneman*  /t/255432/acoustical-treatments-master-thread/10020#post_24493982
> 
> 
> Anybody care to chime in? I attached a very basic layout of my open media room. I want to get the best sounding room I can without bursting the bank. I'm freaking out about the room being open and what acoustical abnormalities this will cause. Especially with having a bar and a tile floor in the back.
> 
> 
> Any thoughts on what I need to do to ensure the best results? Will the in wall treatments I am planning (Roxul SafenSound, RSIC clips, etc) positively affect the sound IN the room?



What are you using the Roxul and the clips for?


Sounds like sound proofing to me (not acoustical treatment of the sound in the room).


Yes, using some method to "decouple" the walls/ceiling will help keep sound in (or just as important, out of) your space. You don't want to stuff your wall/ceiling cavities with the insulation though. There are right and wrong amounts to use.


As for acoustical treatments in the space, there are a lot of things that you CAN do, but they are more for after the room is built (but you should plan for them now).


Corner bass traps at least up front would be good, you could go with a faux-stone wall behind your bar area for a sort of diffusion that doesn't look like a diffusion panel, something on the walls (and if possible, ceiling) for absorption at first reflection points, and then throughout the space will help to clean up echos (you can have some nice looking acoustical panels that look like movie posters, or other artwork, by looking here: DIY Custom-Printed Acoustic Panels - Cheap .


LOTS of options, and we haven't even gotten into the science behind what "stuff' you need to fix or how to fix it without some measurements, etc.


----------



## thestoneman

Thanks for your reply Nick...


Yes, I am soundproofing to keep sound inside the room. I want to be able to listen to movies/music at higher volume without waking the kids...let alone neighbors. I'm pretty clear on how to sound proof. Its the acoustical treatment that can be a bit more interpretive.


10-4 on the bass traps in front. Currently I am planning on a traditional bar area with shelves/bottles as well as a glass wine cellar...all on the back wall facing the screen. Sounds like glass facing the screen wall might not be such a good idea?


----------



## BrutaleZEN

Hi,


I finished doing my side acoustical panels and treat my front wall with Roxul Rockboard 60 and 80. All panels are covered with speaker grill cloth. But now, when I don't turn ON the aircon in the HT Room, my eyes are irritated when I enter the room. It is removed when I turn the aircon ON and the room cool down. Can it be coming from the Rockwool boards ? I really need to find the source of this problem, it make me concern if it turns out it is a health hazard ...


Thanks for your help.


----------



## Nightlord

There are several different possibilities for it being the rockwool, yes. From mold to formaldehyde to urea... whether it's a health issue I would leave to someone of a bio/medical profession to say.


I hope not, I have similar use of similar product...


----------



## myfipie




> Quote:
> my eyes are irritated when I enter the room.



If it turns out to be the Roxul then I would look to make the panels out of Knauf with Ecose. We use it and here is our take on it.

http://www.gikacoustics.com/greensafe/


----------



## Nick in Manitou




> Quote:
> Originally Posted by *BrutaleZEN*  /t/255432/acoustical-treatments-master-thread/10050#post_24497358
> 
> 
> Hi,
> 
> 
> I finished doing my side acoustical panels and treat my front wall with Roxul Rockboard 60 and 80. All panels are covered with speaker grill cloth. But now, when I don't turn ON the aircon in the HT Room, my eyes are irritated when I enter the room. It is removed when I turn the aircon ON and the room cool down.....



If you succeed in finding out definitively what the source of the irritation is, PLEASE post it here so that we can be aware of what you find.


Thanks, and good luck!


Nick


----------



## BIGmouthinDC

One thing is that new materials give off odors to which you might be highly allergic, after a while the odors will go away, don't ask me how long. When you run the AC you are circulating more air and perhaps diluting the strength of the odor, unless this room has a mini-split.


Or there could be some airborne particles as a residual of the construction, you could get a HEPA air filter for the room and let it run a few days and vacuum the room thoroughly


----------



## BrutaleZEN

Thanks guys,


I haven't found yet the source of the irritation.


Recommendation to use other products is out of question. I am living in Thailand and it was already difficult to source Roxul products.


BigMouthinDC, there is no odour. The room has a split aircon not a central aircon. how to source a HEPA air filter ? I have a Sharp air purifier that I will put in the room but is it sufficient ? I have no idea ....

http://www.sharpthai.co.th/product_detail.aspx?l=en&p=45&c=2&sc=6 


I have some odor remover product http://www.dollartree.com/The-Home-Store-Crystal-Beads-Air-Fresheners/p317622/index.pro that I removed from the room too (I really try to found out where it came from, even if it looks insignificant)


All your input will be appreciated.


Regards


----------



## toofast68




> Quote:
> Originally Posted by *BrutaleZEN*  /t/255432/acoustical-treatments-master-thread/10050#post_24501451
> 
> 
> Thanks guys,
> 
> 
> I haven't found yet the source of the irritation.
> 
> 
> Recommendation to use other products is out of question. I am living in Thailand and it was already difficult to source Roxul products.
> 
> 
> BigMouthinDC, there is no odour. The room has a split aircon not a central aircon. how to source a HEPA air filter ? I have a Sharp air purifier that I will put in the room but is it sufficient ? I have no idea ....
> 
> http://www.sharpthai.co.th/product_detail.aspx?l=en&p=45&c=2&sc=6
> 
> 
> I have some odor remover product http://www.dollartree.com/The-Home-Store-Crystal-Beads-Air-Fresheners/p317622/index.pro that I removed from the room too (I really try to found out where it came from, even if it looks insignificant)
> 
> 
> All your input will be appreciated.
> 
> 
> Regards


 

Sounds silly...but can you do a test.

 

Take one of the panels down and say put it in your bathroom...get a fan and move around the air, then go in and see if you have the eye irritation.

 

In my job, I always try to eliminate the obvious.  This MIGHT help.


----------



## BrutaleZEN

Thanks Toofast68,



I will do the test and see.


Will let you know.


----------



## nickbuol

Do you have covering on the back of the panels too, or just the front? I used a cheap, thin fabric to cover the back of my panels for fear of the tiny fibers getting airborne. No issues at all for me, but it was a concern.


----------



## BrutaleZEN

The panels are covered back and front with speaker cloth, so no worries for that ....


----------



## ellisr63

I wonder if you are allergic to it.


----------



## wse


Panels covered 100% also you might want to look at alternatives such as 

 

Bought a few to create a bass trap works great, no worries about toxins 

 

http://www.atsacoustics.com/acoustic-eco-panel.html

 

http://www.bondedlogic.com/acoustical-products/ultrasonic-pro-panels

 

http://www.applegatecottonarmor.com/panelsbaffles.php#.UyoA7F60ZcU

 

http://www.soundaway.com/Acoustic_Cotton_Panels_s/91.htm


----------



## BrutaleZEN

Maybe I am allergic to it but I have 4 more persons that came into the room and have the same irritation to the eyes. So I think I can rule out that I am the only one allergic.


I keep searching ...


----------



## blazar

Wash the room down from top to bottom with wet wipes. A LOT of small dust from construction is always present.


Make sure there is not a radon problem or something else crazy i suppose.


Eyes watering with usual building supplies is VERY unusual with modern paints, etc.


----------



## wse




> Quote:
> Originally Posted by *BrutaleZEN*  /t/255432/acoustical-treatments-master-thread/10050#post_24504744 Maybe I am allergic to it but I have 4 more persons that came into the room and have the same irritation to the eyes. So I think I can rule out that I am the only one allergic.  I keep searching ...


Mold spores are probably the culprit!


----------



## BrentTHX

Quick question for the experts, need to order fabric for my wall panels today, and I was going to order GOM Lapis 2335-2094 . But looking at GOM web page it seams that the FR-701 line has better absorption if I'm reading stuff right? Will the Lapis work fine? or do I need to go to the FR 701.


All walls from 30 inch's off floor to ceiling will be covered in it except where a couple of column's will be to hide subs.


----------



## myfipie

Lapis is going to work fine. That is part of the Anchorage line which is one of my favorites, for not only the quality but how it looks. Very pro looking. We use it all the time.









You can order a sample off there website for free. In fact you can order 20 samples and it will be at your door in 2 days, I believe.


----------



## Skylinestar




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/9810#post_24044990
> 
> 
> Any enclosed air cavity has the potential to resonate and color the sound of the space. Loosely fill with insulation - the cheaper the better.


 http://ts3.mm.bing.net/th?id=HN.608032953894569572&pid=1.7 

^ The image above shows the suspended plaster ceiling support construction. The aluminum channels are the support members. There's about 1 feet gap between the plaster ceiling panels and the concrete ceiling above it.

Should I bother to fill up the wide space (15' x 25' x 1') with insulation? Will it affect the sound frequency response? (I doubt it will because the ceiling is not perforated).

Please advise.


----------



## wse

Has any one hear of the Triple Effect and what does it mean?

http://www.greengluecompany.com/technical-library?field_resource_type_tid=All&field_faq_category_tid=All&field_customer_type_tid=All&sort_by=created&sort_order=DESC&page=1


----------



## ellisr63




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/10050#post_24510672
> 
> http://ts3.mm.bing.net/th?id=HN.608032953894569572&pid=1.7
> 
> ^ The image above shows the suspended plaster ceiling support construction. The aluminum channels are the support members. There's about 1 feet gap between the plaster ceiling panels and the concrete ceiling above it.
> 
> Should I bother to fill up the wide space (15' x 25' x 1') with insulation? Will it affect the sound frequency response? (I doubt it will because the ceiling is not perforated).
> 
> Please advise.


I would say yes... As I would think the plaster ceiling will resonate. I am not an expert though. We will see what others asy.


----------



## granroth




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10000_100#post_24515404
> 
> 
> Has any one hear of the Triple Effect and what does it mean?
> 
> http://www.greengluecompany.com/technical-library?field_resource_type_tid=All&field_faq_category_tid=All&field_customer_type_tid=All&sort_by=created&sort_order=DESC&page=1



Yes, the triple leaf effect refers to a wall where you have Mass-Air-Mass-Air-Mass. Think of it like Drywall + Studs + Drywall + Studs + Drywall. This is an excellent example of how non-intuitive some of acoustics and soundproofing is -- you'd think that adding another layer of mass to a wall would help, but it actually makes things significantly worse!


The most accessible into I've seen on the topic is here: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/ 


If you want the actual research done on the topic (surprisingly readable for a research paper): http://www.nrc-cnrc.gc.ca/ctu-sc/ctu_sc_n1


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/10050#post_24515982
> 
> 
> Yes, the triple leaf effect refers to a wall where you have Mass-Air-Mass-Air-Mass. Think of it like Drywall + Studs + Drywall + Studs + Drywall. This is an excellent example of how non-intuitive some of acoustics and soundproofing is -- you'd think that adding another layer of mass to a wall would help, but it actually makes things significantly worse!
> 
> 
> The most accessible into I've seen on the topic is here: http://www.soundproofingcompany.com/soundproofing101/triple-leaf-effect/
> 
> 
> If you want the actual research done on the topic (surprisingly readable for a research paper): http://www.nrc-cnrc.gc.ca/ctu-sc/ctu_sc_n1


I am still not understanding the Triple Leaf concept...


I had a single frame wall that was like this... drywall>2x4 (with insulation)>plywood>drywall. I wanted to add one more layer of drywall to one side of the wall and was told it would be a triple leaf even though there is only one cavity. I was told to remove the drywall and plywood from the one side and build a second wall with an air gap in between the 2 walls and then add OSB (or drywall) followed by GG and another drywall layer. Both walls only have one air gap... How is one a triple leaf and the other not?


----------



## Nightlord

Triple leaf concept... If you have two different springs that you understand... And then you attach them together.... The resulting resonance point of the could surprise you.


----------



## Nightlord




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10050#post_24516196
> 
> 
> I wanted to add one more layer of drywall to one side of the wall and was told it would be a triple leaf even though there is only one cavity.



That's not correct. Mounting another layer of dw directly on top of the old one is not a triple leaf. You may want GG inbetween possibly, but do not let the triple leaf stop you,if you add no new cavity it's not triple leaf.


----------



## ellisr63




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/10050#post_24516333
> 
> 
> That's not correct. Mounting another layer of dw directly on top of the old one is not a triple leaf. You may want GG inbetween possibly, but do not let the triple leaf stop you,if you add no new cavity it's not triple leaf.


Thanks for confirming what I thought. The advise was given to me by a Company that everyone says to go to too. Man that pisses me off, as it took 2 days to rip open that wall, and we still haven't finished building the new wall. It put me enough over budget that I can't get the GreenGlue at this time too.


----------



## Nightlord




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10050#post_24516375
> 
> 
> Thanks for confirming what I thought. The advise was given to me by a Company that everyone says to go to too. Man that pisses me off, as it took 2 days to rip open that wall, and we still haven't finished building the new wall. It put me enough over budget that I can't get the GreenGlue at this time too.



Sorry to hear it. But if you have ripped it up, at least take some comfort in that a wall with osb behind (double) dw will get you a very very good wall.


----------



## ellisr63




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/10050#post_24516405
> 
> 
> Sorry to hear it. But if you have ripped it up, at least take some comfort in that a wall with osb behind (double) dw will get you a very very good wall.


Yeah, I know. It was the only wall that was not going to be double walled. If I hadn't had to do that we might have had enough money to get the rest of the walls up and start testing for acoustic treatments. We currently have 2 out of the four walls covered with OSB... As soon as we get this wall finished we will be doing the last wall with OSB and then the ceiling with clips and channels. Last will be drywall on all walls and ceiling.


What made it so bad was whoever did the work before used 1/4" plywood nailed every 3" inches and then drywalled over that. It was a lot of work to remove that wall not to mention we have to buy all the OSB and drywall again just to get the new wall up to where it was instead of just a few sheets of drywall added to the old wall.


----------



## wse


Other great reads

 

http://www.nrc-cnrc.gc.ca/ctu-sc/files/doc/ctu-sc/ctu-n66_eng.pdf

 

http://www.nrc-cnrc.gc.ca/ctu-sc/files/doc/ctu-sc/ctu-n51_eng.pdf

 

http://www.nrc-cnrc.gc.ca/ctu-sc/files/doc/ctu-sc/ctu-n25_eng.pdf


----------



## wse


So to insulate my garage for sound coming in and getting out.  I don't need to rip of the drywall yes, I was thinking of building new wall in front of the walls with new 2x4 and use resilient channels for the new wall with either these http://www.greengluecompany.com/products/dry-wall or this one Quiet Rock http://www.quietrock.com/quietrock-545

 

Suggestions


----------



## granroth




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10000_100#post_24516712
> 
> 
> So to insulate my garage for sound coming in and getting out.  I don't need to rip of the drywall yes, I was thinking of building new wall in front of the walls with new 2x4 and use resilient channels for the new wall with either these http://www.greengluecompany.com/products/dry-wall or this one Quiet Rock http://www.quietrock.com/quietrock-545



I think one of the issues that confuses the whole triple leaf or not topic is the habit of referring to walls as a singular unit. That can lead to a lot of misunderstandings. It's better to refer to the individual elements of construction of the wall or walls from left-to-right.


So in your case, if you have a wall like so:


Drywall + Studs + Drywall


And then you create a second wall in front of that so it looks like:


Drywall + Studs + Air + Drywall + Studs + Drywall


Then you are facing a triple leaf. If, however, you remove the left-most drywall from the original wall, then you'll have:


Drywall + Studs + Air + Studs + Drywall


And you're set!


As far as drywall + Green Glue vs QuietRock -- they both do the same thing in the end. That is, both have substantial mass and providing a damping layer. The only real differences are cost and thickness. Quiet Rock is going to run maybe 5x the cost of DW+GG and will be some fraction of an inch thinner. Generally speaking, though, they should have very similar performance.


----------



## ellisr63




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/10080#post_24516867
> 
> 
> I think one of the issues that confuses the whole triple leaf or not topic is the habit of referring to walls as a singular unit. That can lead to a lot of misunderstandings. It's better to refer to the individual elements of construction of the wall or walls from left-to-right.
> 
> 
> So in your case, if you have a wall like so:
> 
> 
> Drywall + Studs + Drywall
> 
> 
> And then you create a second wall in front of that so it looks like:
> 
> 
> Drywall + Studs + Air + Drywall + Studs + Drywall
> 
> 
> Then you are facing a triple leaf. If, however, you remove the left-most drywall from the original wall, then you'll have:
> 
> 
> Drywall + Studs + Air + Studs + Drywall
> 
> 
> And you're set!
> 
> 
> As far as drywall + Green Glue vs QuietRock -- they both do the same thing in the end. That is, both have substantial mass and providing a damping layer. The only real differences are cost and thickness. Quiet Rock is going to run maybe 5x the cost of DW+GG and will be some fraction of an inch thinner. Generally speaking, though, they should have very similar performance.


I wish i would have asked you instead of the Supplier... It would have saved us a lot of work and money!


----------



## wse




> Quote:
> Originally Posted by *granroth*  /t/255432/acoustical-treatments-master-thread/10080#post_24516867 I think one of the issues that confuses the whole triple leaf or not topic is the habit of referring to walls as a singular unit. That can lead to a lot of misunderstandings. It's better to refer to the individual elements of construction of the wall or walls from left-to-right.
> 
> 
> So in your case, if you have a wall like so:
> 
> 
> Drywall + Studs + Drywall
> 
> 
> And then you create a second wall in front of that so it looks like:
> 
> 
> Drywall + Studs + Air + Drywall + Studs + Drywall
> 
> 
> Then you are facing a triple leaf. If, however, you remove the left-most drywall from the original wall, then you'll have:
> 
> 
> Drywall + Studs + Air + Studs + Drywall
> 
> 
> And you're set!  As far as drywall + Green Glue vs QuietRock -- they both do the same thing in the end. That is, both have substantial mass and providing a damping layer. The only real differences are cost and thickness. Quiet Rock is going to run maybe 5x the cost of DW+GG and will be some fraction of an inch thinner. Generally speaking, though, they should have very similar performance.


OK but it really is

 

Drywall + Studs + insulation since they are outside walls + Drywall

 

And then you create a second wall in front of that so it looks like:  Drywall + 2 x4 Studs + Insulation + Drywall + Air 2inches + DryWall + Insulation + 2 x6 Studs + Decoupling Chanels+ Drywall

 

So do I still get the Triple Leaf?

 

I posted that in an other thread but maybe here is where it should be

 

So you are saying I have to remove the drywall inside and create an other wall so it wood be outside Gypsum + insulation + studs + insulation + studs + Dry wall that's the only way to avoids the Triple Leaf?

 

So I don't understand how to build a room with in a room is this what it is? Just double studs and insulation with a gap in between? What about adding a decoupling channel to the inside?


----------



## ellisr63




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10080#post_24516910
> 
> 
> OK but it really is
> 
> 
> Drywall + Studs + insulation since they are outside walls + Drywall
> 
> 
> And then you create a second wall in front of that so it looks like:  Drywall + Studs + Insulation + Drywall + Air 2inches + DryWall + Insulation + Studs + Drywall
> 
> 
> So do I still get the Triple Leaf?


You need to rip out the one layer of drywall in your case or you have a triple leaf. If you just add more mass to the existing wall it won't be a triple leaf. I think if you had like a foot or two air cavity it would not be a triple leaf, but I am not sure about that part.


Listen to Granroth.


----------



## ellisr63




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10080#post_24516910
> 
> 
> OK but it really is
> 
> 
> Drywall + Studs + insulation since they are outside walls + Drywall
> 
> 
> And then you create a second wall in front of that so it looks like:  Drywall + 2 x4 Studs + Insulation + Drywall + Air 2inches + DryWall + Insulation + 2 x6 Studs + Decoupling Chanels+ Drywall
> 
> 
> So do I still get the Triple Leaf?


I think the key is that there is no drywall on each side of the airspace but on the outside of the studs. Maybe if you look at it this way... Your original wall of drywall+studs+drywall is a single leaf and has an airspace in it even though it is filled with fiberglass. I you build another wall just like the original wall you now have the original airspace + airspace between the 2 walls+airspace in the new wall, which makes it a triple leaf. Does that make more sense, or am I making it more confusing?


----------



## HopefulFred




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10080#post_24516939
> 
> 
> Your original wall of drywall+studs+drywall is a single leaf and has an airspace in it even though it is filled with fiberglass.


No. Every time you have a drywall layer (whether it's made of one or more actual plies of gypsum board) you have a leaf. A standard wall (both interior and exterior) has two sheathing layers - that's two leaves.


You can build two walls near each other and avoid a triple leaf if each wall only has sheathing on one side. Drywall - 2x4 air space 2x4 - double drywall (or more) with (or without) constrained damping. This is the best assembly.


----------



## ellisr63




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/10080#post_24516975
> 
> 
> No. Every time you have a drywall layer (whether it's made of one or more actual plies of gypsum board) you have a leaf. A standard wall (both interior and exterior) has two sheathing layers - that's two leaves.
> 
> 
> You can build two walls near each other and avoid a triple leaf if each wall only has sheathing on one side. Drywall - 2x4 air space 2x4 - double drywall (or more) with (or without) constrained damping. This is the best assembly.



Ok... I agree with you on the double wall construction, which is what we went with but according to the GG site...

A standard wall is a double leaf, correct? The only way to have a single leaf would be to have no air cavity at all, correct? You could take ten layers of osb and screw them together and still have a single leaf according to the green glue site . As soon as you have more than one air cavity you have a triple leaf or Quad leaf (and so on), correct? This is very confusing to me, and just when I think I have it someone says i'm wrong... I hope I am understanding this correctly now.


----------



## HopefulFred

You've got it now.


----------



## ellisr63




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/10080#post_24517133
> 
> 
> You've got it now.



Thanks for helping me get this down. I am glad i finally have the full grasp of it


----------



## wse




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10080#post_24516939 I think the key is that there is no drywall on each side of the airspace but on the outside of the studs. Maybe if you look at it this way... Your original wall of drywall+studs+drywall is a single leaf and has an airspace in it even though it is filled with fiberglass. I you build another wall just like the original wall you now have the original airspace + airspace between the 2 walls+airspace in the new wall, which makes it a triple leaf. Does that make more sense, or am I making it more confusing?


So you are saying I have to remove the drywall inside and create an other wall so it wood be outside Gypsum + insulation + studs + insulation + studs + Dry wall that's the only way to avoids the Triple Leaf?

 

So I don't understand how to build a room with in a room is this what it is? Just double studs and insulation with a gap in between? What about adding a decoupling channel to the inside?


----------



## ellisr63




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10080#post_24518749
> 
> 
> So you are saying I have to remove the drywall inside and create an other wall so it wood be outside Gypsum + insulation + studs + insulation + studs + Dry wall that's the only way to avoids the Triple Leaf?


Yes, if you want a double wall... Otherwise you can just add more drywall to your existing wall.


----------



## wse




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10080#post_24518761 Yes, if you want a double wall... Otherwise you can just add more drywall to your existing wall.


 

But that won't help low frequencies?


----------



## ellisr63




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10080#post_24518782
> 
> 
> But that won't help low frequencies?


You could build some bass traps.


----------



## ellisr63




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10080#post_24518749
> 
> 
> So you are saying I have to remove the drywall inside and create an other wall so it wood be outside Gypsum + insulation + studs + insulation + studs + Dry wall that's the only way to avoids the Triple Leaf?
> 
> 
> So I don't understand how to build a room with in a room is this what it is? Just double studs and insulation with a gap in between? What about adding a decoupling channel to the inside?


You can add clips but they must be to a wall side that is at the studs... In other words you need to remove the drywall and OSB if it is there, and then install the clips. You can also add clips to a double wall if desired but I think it would be overkill for most people. If your outer walls are 2x6s, you could make them in to a staggered wall I believe but it might get a little complicated spacing out the inside 2x4s in the 2x6 wall.


----------



## ctviggen




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10050#post_24516712
> 
> 
> So to insulate my garage for sound coming in and getting out.  I don't need to rip of the drywall yes, I was thinking of building new wall in front of the walls with new 2x4 and use resilient channels for the new wall with either these http://www.greengluecompany.com/products/dry-wall or this one Quiet Rock http://www.quietrock.com/quietrock-545
> 
> 
> Suggestions



You have to be careful with the interior of garages, as the assembly has to be fire rated for a certain time. Depending on where you are, an assembly using resilient channel (on the wall facing the garage) might violate code, as this assembly might not have a proper fire rating.


----------



## wse




> Quote:
> Originally Posted by *ctviggen*  /t/255432/acoustical-treatments-master-thread/10080#post_24519462 You have to be careful with the interior of garages, as the assembly has to be fire rated for a certain time. Depending on where you are, an assembly using resilient channel (on the wall facing the garage) might violate code, as this assembly might not have a proper fire rating.


Good point


----------



## Nightlord




> Quote:
> Originally Posted by *wse*  /t/255432/acoustical-treatments-master-thread/10080#post_24518782
> 
> 
> But that won't help low frequencies?



Yes,it would. Perhaps not the optimum way, but "for bass the only solution is added mass".


----------



## avip2u

Hi everyone,


The SOUND PROOFING thread (this one: http://www.avsforum.com/t/1509173/soundproofing-master-thread/0_50 ) begins with a nice Q&A on the basics with a consolidated set of links to "further reading". It explains the difference between SOUND PROOFING and ACOUSTIC TREATMENTS.


My question is, is there a similar basic guide / Q&A on ACOUSTIC TREATMENTS ? I am a beginner at this so I need "A.T. for Dummies".


Thanks!


----------



## wse




> Quote:
> Originally Posted by *avip2u*  /t/255432/acoustical-treatments-master-thread/10080#post_24523222
> 
> 
> Hi everyone, The SOUND PROOFING thread (this one: http://www.avsforum.com/t/1509173/soundproofing-master-thread/0_50 ) begins with a nice Q&A on the basics with a consolidated set of links to "further reading". It explains the difference between SOUND PROOFING and ACOUSTIC TREATMENTS. My question is, is there a similar basic guide / Q&A on ACOUSTIC TREATMENTS ? I am a beginner at this so I need "A.T. for Dummies". Thanks!


 http://www.gikacoustics.com/educational-videos/ 

http://www.rivesaudio.com/files/GEC_BOOK_89-95.pdf 

http://www.soundonsound.com/sos/dec09/articles/beginnersacoustics.htm 

http://www.subwoofer-builder.com/qrd.htm 

http://downloads.bbc.co.uk/rd/pubs/reports/1992-10.pdf


----------



## CheYC

Since I haven't been getting much love in the audio theory section, let me try linking my post in here, had some questions on treating my basement: http://www.avsforum.com/t/1524108/another-advice-on-room-treatments-thread 


Thanks!


----------



## chexi1

I have a Seymour AV AT screen to install in my home theater that is presently being retrofited. I am trying to determine how far away from the actual wall I should mount the screen, and, accoustically speaking, that analysis involves at least the following considerations for which I solicit your collective wisdom:


1. How far away from the back of the screen should the speakers be?

2. I am planning on using some rigid fiberglass on the wall behind the screen. Is the jump from 2" to 4" worth it?

3. Assuming I deaden the wall behind the screen, how far away from the wall (if at all) should I be placing my speakers? With no wall treatment, I believe I should have the speakers at least 6" off the rear walls, but the more AT I do on the rear wall, the less space I have to work with without moving the sreen forward). So the crux of the question is, do you need to have your front mains and center away from the rear wall if you use absorption on the wall behind them? If you still do need to move them away from the wall, is it better to have a few more inches of empty space or a few more inches of absorption material? I would think that the absorbption material is more important, but what do I know? I'm no acoustician.


I do want good 2 channel audio as well (in case that matters). I realize I may need a temporary seat closer than my theater seats for optimum 2 channel audio.


Thank you.


----------



## wse




> Quote:
> Originally Posted by *chexi1*  /t/255432/acoustical-treatments-master-thread/10080#post_24528219
> 
> 
> I do want good 2 channel audio as well (in case that matters). I realize I may need a temporary seat closer than theater seats for optimum 2 channel audio. Thank you.



I move my center seat forward two feet for stereo so I sit seven feet from the speakers


----------



## nvidio




> Quote:
> Originally Posted by *chexi1*  /t/255432/acoustical-treatments-master-thread/10080#post_24528219
> 
> 
> I have a Seymour AV AT screen to install in my home theater that is presently being retrofited. I am trying to determine how far away from the actual wall I should mount the screen, and, accoustically speaking, that analysis involves at least the following considerations for which I solicit your collective wisdom:
> 
> 
> 1. How far away from the back of the screen should the speakers be?
> 
> 2. I am planning on using some rigid fiberglass on the wall behind the screen. Is the jump from 2" to 4" worth it?
> 
> 3. Assuming I deaden the wall behind the screen, how far away from the wall (if at all) should I be placing my speakers? With no wall treatment, I believe I should have the speakers at least 6" off the rear walls, but the more AT I do on the rear wall, the less space I have to work with without moving the sreen forward). So the crux of the question is, do you need to have your front mains and center away from the rear wall if you use absorption on the wall behind them? If you still do need to move them away from the wall, is it better to have a few more inches of empty space or a few more inches of absorption material? I would think that the absorbption material is more important, but what do I know? I'm no acoustician.
> 
> 
> I do want good 2 channel audio as well (in case that matters). I realize I may need a temporary seat closer than my theater seats for optimum 2 channel audio.
> 
> 
> Thank you.


Placing free-standing speakers within inches from the wall behind them is never a good idea, but you could try flush-mounting them in soffits instead. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=718


----------



## sdurani




> Quote:
> Originally Posted by *chexi1*  /t/255432/acoustical-treatments-master-thread/10080#post_24528219
> 
> 
> How far away from the back of the screen should the speakers be?


At least 6 inches away according to Anthony Grimani, who tested several AT screens for a comprehensive article in Widescreen Review.


> Quote:
> Originally Posted by *chexi1*  /t/255432/acoustical-treatments-master-thread/10080#post_24528219
> 
> 
> I am planning on using some rigid fiberglass on the wall behind the screen. Is the jump from 2" to 4" worth it?


Yes, it will make the absorption closer to broadband. 6" would be better, or 4" placed 4" from the wall (air gap). But if you can't do either of those, then going from 2" to 4" is definitely worth it.


> Quote:
> Originally Posted by *chexi1*  /t/255432/acoustical-treatments-master-thread/10080#post_24528219
> 
> 
> Assuming I deaden the wall behind the screen, how far away from the wall (if at all) should I be placing my speakers?


IF the wall is dead, then there won't be any reflections to cause boundry cancellations. In which case, you can put the speakers as close to the wall as you want.


----------



## nvidio




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/10080#post_24530574
> 
> 
> IF the wall is dead, then there won't be any reflections to cause boundry cancellations. In which case, you can put the speakers as close to the wall as you want.


That is correct, but for a wall to _become_ dead, or near dead down to the lowest frequency a satellite speaker can reproduce, it requires a layer of porous absorption that is a lot thicker than 6" so that's why flush mounting the speakers in a soffit is generally a much better idea.


P.S. - Here you can see what the arbsorption curve of a porous absorber 1 ft. thick typically looks like. http://www.acousticmodelling.com/mlink.php?n=1&r=r&im=1&s14=2&d14=305&v14=5000


----------



## sdurani




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/10080#post_24530631
> 
> 
> That is correct, but for a wall to _become_ dead, or near dead down to the lowest frequency a satellite speaker can reproduce, it requires a layer of porous absorption that is a lot thicker than 6" so that's why flush mounting the speakers in a soffit is generally a much better idea.


Why the lowest frequency the speaker can produce? Placing a speaker against the front wall means that its woofer will be about a foot or so from the wall, making the boundry cancellation around 300Hz. How much lower than that do you need to absorb?


BTW, the calculator is at variance from absorption coefficients from manufacturers posted here: http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## myfipie




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10080#post_24527478
> 
> 
> Since I haven't been getting much love in the audio theory section, let me try linking my post in here, had some questions on treating my basement: http://www.avsforum.com/t/1524108/another-advice-on-room-treatments-thread
> 
> 
> Thanks!



I just commented on your thread.










> Quote:
> If you can I would flip the screen to lower wall. That is going to give you much better symmetry in front of the room, which is pretty important. At that point I would just treat the room with as much bass trapping in corners as possible with deep absorption/diffusion for the back wall. You also need absorption for the early reflection points. You can use the following videos to give you a hand.
> http://www.gikacoustics.com/educational-videos/


----------



## myfipie

This going to go against the gain a bit with HT, but pushing the speaker out into the room is going to push the SBIR lower, which makes it harder to control. I would start with the speakers as close the wall as possible with as deep as absorption you can handle. Every speaker/room is going to be different, so If you want to make sure of the response then I would HIGHLY recommend testing different speaker locations. You can use REW for this. Here is a video on how to set up the program.
http://www.gikacoustics.com/room-eq-wizard-tutorial/ 


I do agree that the best of all is to flush mount.


----------



## artur9




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10080#post_24531150
> 
> 
> Every speaker/room is going to be different, so If you want to make sure of the response then I would HIGHLY recommend testing different speaker locations. You can use REW for this. Here is a video on how to set up the program.
> http://www.gikacoustics.com/room-eq-wizard-tutorial/



There's also a helpful REW thread here full of info and knowledgeable people.


----------



## chexi1

The interesting thing about my speakers is that they have a 10" passive SLAPS woofer at the bottom (side). These are Platine Noiree by Earthquake. I suppose I could mount them as far as humanly possible against the real wall and build the Acoustic foam deep around them to be flush with the front of the speakers, but I do not know (a) if that is really sufficient to be flush mounted like a built in speaker for accoustic purposes or (b) what that would do to the passive woofers. One thing really nice about the Platine Noiree system is the seamless bass between my 15" earthquake supernova sub and the mains (and center). The two channel base is really quite good with just the mains in large mode.


However, "flush mounting" would certainly help me move my screen back as far as possible.


I do have an additional complication that I have not yet disclosed. This room started as a guest bedroom in my guest house. My wife wanted to keep it as a tweener, so we installed a murphy bed along one of the side walls. The murphy bed will either wreak havoc with my accoustics or do nicely as a diffuser.We will see. When closed up, the front of it is basically a book case where all the Blu rays are going.


The wall that is behind where my screen will be has 2 glass french doors that open to a Juliette balcony. I need access to these doors for WAF, which is why I have a drop down Seymour screen instead of just using a fixed with a false wall. I was planning on building fiberglass AT for the doors that I could mount with velcrow and remove them for the 2 weeks out of the year that this room might actually be used as a guest bedroom. My point here is that the center speaker is going to be in front of one or both of those glass doors. If I flush mount, it's going to be right in front of those glass doors (although I could probably use thinner AT panels on the glass). At any rate, it's going to be fun figuring this all out, and your input is certainly welcome.


----------



## nvidio




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/10080#post_24530748
> 
> 
> Why the lowest frequency the speaker can produce? Placing a speaker against the front wall means that its woofer will be about a foot or so from the wall, making the boundry cancellation around 300Hz. How much lower than that do you need to absorb?
> 
> 
> BTW, the calculator is at variance from absorption coefficients from manufacturers posted here: http://www.bobgolds.com/AbsorptionCoefficients.htm


Assuming the speaker enclosure is ~1 ft. deep, and assuming the porous absorber behind it is 6" thick, the distance of the woofer face from the wall behind the porous absorber will be ~1 ft. + 6" = ~1.5 ft. Meaning, the quarter wavelength cancellation will be ~188 Hz. Here is what the absorption curve of a 6" porous absorber typically looks like. http://www.acousticmodelling.com/mlink.php?n=1&r=r&im=1&s14=2&d14=152&v14=11500 

Please note the _gas flow resistivity_ of a porous absorber is, in practice, a more accurate performance indicator than a table of absorption coefficients. This is due to the way measurements are conducted, as has been explained by Ethan Winer in this article (see "The Numbers Game"). http://realtraps.com/art_measure.htm 

Here is another interesting discussion thread. http://www.gearslutz.com/board/studio-building-acoustics/823983-tool-calculating-front-wall-sbir.html


----------



## sdurani




> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/10110#post_24536067
> 
> 
> Assuming the speaker enclosure is ~1 ft. deep, and assuming the porous absorber behind it is 6" thick, the distance of the woofer face from the wall behind the porous absorber will be ~1 ft. + 6" = ~1.5 ft.


I have absorption between my L/R speakers, so that the speakers themselves are against the wall (i.e., they need not be on top of the absorber panel).


> Quote:
> Originally Posted by *nvidio*  /t/255432/acoustical-treatments-master-thread/10110#post_24536067
> 
> 
> Here is what the absorption curve of a 6" porous absorber typically looks like.


Looks like it absorbs enough to minimze the boundry cancellation, even at 200Hz.


----------



## Francky


Need a litle help here. I read most of the 300+ pages of this thread. I'm doing some treatment to my HT on a trial and error basis. So far i've added bass traps and some insulation on the front wall with Roxul Comfortboard IS 1.5 inches thick and walls first reflection point. First, is this material too dense  and second, what i have done up to now helped quit a bit but one thing is bothering me. Center channel feels "isolated" What i mean is when soundtrack is just dialog it clearly feels like where it's coming from. When all speakers are in use, dialog and soundtrack/sfx all speakers blend in realy well, good and wide soundstage and precise. But when sound level is above or near 80db dialog gets kinda hard to understand. At low volume, dialog is clear.


----------



## HopefulFred

Since you're doing this guess-and-check style, I don't mind guessing. It sounds to me like two separate issues.


The localization of the center I suspect has to do with the absence of lateral reflections. Perhaps the panel positions could be tweaked to allow lateral reflections from the center loudspeaker - this should broaden the apparent source. However, the position and design of the loudspeaker will play a large role in the results of that change.


The intelligibility problem at high level sounds like masking caused be lingering low frequency ringing issues (or maybe SBIR positional problems). The likely solution will be absorption either on the wall behind the center loudspeaker or on the wall behind the listening position.


----------



## poster

Hoping to get some advice on the worth of adding a door to my modest media room in our basement.


Currently, when you come down the stairs, there is an open entry way to the media room. The entry is dry-walled, so you can't see the frame of the entry way when walking into the room. Once inside the room, it is more of a long rectangle shaped room that is 11.5' W x 25' L x 6.8 H (short ceiling :-( ). I don't have a great sound system, but may try to start to upgrade in the future. I did get some GIK tri-traps stacked in each front corner behind my projection screen, along with a pair of bass traps on each side of the side walls in the front of the room. Nothing else has been done in the room to improve the acoustics, as most of this room was finished when we purchased the house, although I am not sure I could afford a total soundproofing anyways. 


Knowing all this, would adding a door to the entry way be worth the investment? I assume it would help regardless as it would keep the sound enclosed in the room when closed off, but would it be that significant of a difference?


I am not as handy as I wish I could be, so I would want someone to install it. Also concerned on how much that would cost, as there is no frame showing, and I am concerned it would cost alot of labor time to get it installed. The entry is also wider then more pre cut doors, at 41.5 " W, so that would also add to the cost.


Would appreciate any advice from someone with more knowledge. Thank you.


----------



## blazar




> Quote:
> Originally Posted by *poster*  /t/255432/acoustical-treatments-master-thread/10110#post_24540250
> 
> 
> Hoping to get some advice on the worth of adding a door to my modest media room in our basement.
> 
> 
> Currently, when you come down the stairs, there is an open entry way to the media room. The entry is dry-walled, so you can't see the frame of the entry way when walking into the room. Once inside the room, it is more of a long rectangle shaped room that is 11.5' W x 25' L x 6.8 H (short ceiling :-( ). I don't have a great sound system, but may try to start to upgrade in the future. I did get some GIK tri-traps stacked in each front corner behind my projection screen, along with a pair of bass traps on each side of the side walls in the front of the room. Nothing else has been done in the room to improve the acoustics, as most of this room was finished when we purchased the house, although I am not sure I could afford a total soundproofing anyways.
> 
> 
> Knowing all this, would adding a door to the entry way be worth the investment? I assume it would help regardless as it would keep the sound enclosed in the room when closed off, but would it be that significant of a difference?
> 
> 
> I am not as handy as I wish I could be, so I would want someone to install it. Also concerned on how much that would cost, as there is no frame showing, and I am concerned it would cost alot of labor time to get it installed. The entry is also wider then more pre cut doors, at 41.5 " W, so that would also add to the cost.
> 
> 
> Would appreciate any advice from someone with more knowledge. Thank you.



It takes less subwoofer power if you close it off... If you have modest subs, the bass is likely to improve if nothing else


----------



## poster




> Quote:
> Originally Posted by *blazar*  /t/255432/acoustical-treatments-master-thread/10110#post_24541519
> 
> 
> It takes less subwoofer power if you close it off... If you have modest subs, the bass is likely to improve if nothing else



Thanks for the input! It doesn't sound like it would help as much as putting the funds towards something else, so I will probably leave it for now.


----------



## Francky




> Quote:
> Originally Posted by *HopefulFred*  /t/255432/acoustical-treatments-master-thread/10110#post_24540016
> 
> 
> Since you're doing this guess-and-check style, I don't mind guessing. It sounds to me like two separate issues.
> 
> 
> The localization of the center I suspect has to do with the absence of lateral reflections. Perhaps the panel positions could be tweaked to allow lateral reflections from the center loudspeaker - this should broaden the apparent source. However, the position and design of the loudspeaker will play a large role in the results of that change.
> 
> 
> The intelligibility problem at high level sounds like masking caused be lingering low frequency ringing issues (or maybe SBIR positional problems). The likely solution will be absorption either on the wall behind the center loudspeaker or on the wall behind the listening position.


i have 2 subs, 1 in the front and 1 behind the couch (back of the room). I shut down the front one wich was on 180deg phase (thought it sounded better that way) and not sure if it's in my head but sure made a significant difference to me. Oh and the front wall is covered from floor to 6 inches above ear position with Roxul comfortboard IS, 1.5 inches thick and i have one 4x8 panel of this stuff on the wall behind main listening position (back wall of the room)


----------



## HopefulFred

Francky, that's interesting. I'd be interested in other people's opinions, but it sounds to me like it's time to invest in a mic and learn to use REW.


----------



## Francky


Yeah i know. I wanted to try "the basics" (if such a thing exists) and see what i could get out of it. Think I'm going to seek professional help (for the room..... not for me!!!) in the mean time if anybody wants to theorize about what i could try, I'm all ears (and eyes). Oh one more thing about localisation to center channel, when listening to regular tv i dont get that effect. I'm starting to wonder if it might be the AVR's treatment.


----------



## Timoxx4

I have just been measuring my system with REW and have found on the RT60 graph the following and was worried i might have inadvertently over dampened my room on the high end possibly ? Can anyone offer any insight or possible things i could do to help in some way if its needed ?


The room is a small HT i built about 5 years ago and have treated the room as described in this thread. Lower half of the walls up to just above ear height covered in 1" rigid fiberglass. Front wall is 100% covered in 1" rigid fiberglass.Carpet on floor. And i have 2 corner bass traps made of 4" rigid fiberglass. Room dimentions are 5m x 3.5m x 2m


The is the graph in REW.


----------



## Nightlord

First of all - how does it sound? If you don't hear a problem, then no need to fix it...


----------



## Timoxx4

Sounds alright. But i am used too it and don't know any different as i don't have anything to compare it against. I saw the graph and thought wow that cant be good.


----------



## myfipie

Viewing the RT60 really is not going to give you the information you need. What you want to view is the waterfall for the most part. If you can post the REW file and I can take a look in my REW file for you. Would be great to see a test of the right and left speaker alone to be able to view the ETC graph.


Needless to say, if you have used 1" all over the room I can bet you are still have some large low end problems and totally dead on the high end.


----------



## jlpowell84

I posted this in the few thread but I need timely answers so I will double up here to










Last question before I purchase the final materials tomm. I went and looked at fabric at a fabric store (Jo-Ann Fabric). I found the stuff labeled "speaker cloth but it appeared thicker than I anticipated. When I blew on it air went through but some stopped up. My speaker grills on my JTR's have thinner fabric. The burlap was also right next to it and had about the same properties with the blow testing.


So my question is...If I have my wife speak through it and I can't tell a difference then it is fine correct? I know burlap is supposed to be basically 100% acoustically transparent correct?


----------



## Timoxx4




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10110#post_24567312
> 
> 
> Viewing the RT60 really is not going to give you the information you need. What you want to view is the waterfall for the most part. If you can post the REW file and I can take a look in my REW file for you. Would be great to see a test of the right and left speaker alone to be able to view the ETC graph.
> 
> 
> Needless to say, if you have used 1" all over the room I can bet you are still have some large low end problems and totally dead on the high end.



Yeah sure here is the REW .mdat dosent have the right speaker though. Just the left on its own and the subs.

http://www.hometheatershack.com/forums/attachments/rew-forum/47980d1396423564-sub-distance-setting-phase-alignment-problem-tims-subs-l-main.mdat


----------



## artur9




> Quote:
> Originally Posted by *jlpowell84*  /t/255432/acoustical-treatments-master-thread/10110#post_24570791
> 
> 
> I know burlap is supposed to be basically 100% acoustically transparent correct?



There's acoustically transparent and then there's suitable for making acoustical panels. For the latter, the important thing is that it absorbs or reflects across the frequency band evenly.


For any particular fabric, the only way to know is to test it. Since you are set up for REW, you have everything you need to test.


Get a sample of the product and drape it over your speaker. Do a sweep. Then take it off and sweep again and see if there are any differences.


All that being said, burlap is one of the fabrics of choice. One serious downside to it, though, is that it is not flame retardant. That could impact your home insurance or otherwise cause concern.


----------



## myfipie

"So my question is...If I have my wife speak through it and I can't tell a difference then it is fine correct? I know burlap is supposed to be basically 100% acoustically transparent correct"




Yes, but I would throw in a few "what did you say honey?" to just mess with her.


----------



## myfipie




> Quote:
> Originally Posted by *Timoxx4*  /t/255432/acoustical-treatments-master-thread/10110#post_24571306
> 
> 
> Yeah sure here is the REW .mdat dosent have the right speaker though. Just the left on its own and the subs.
> 
> http://www.hometheatershack.com/forums/attachments/rew-forum/47980d1396423564-sub-distance-setting-phase-alignment-problem-tims-subs-l-main.mdat



I am not sure the tests are right. The ETC looks kind of strange. Zero ms should be at zero db and then it should taper off.


----------



## jlpowell84

Well its been about a 14 hr day shopping for materials at numerous places, lots of cutting and oh the hole saw holes that were cut. Not done yet but hopefully tomm with many pics and yes the measurements. Sanding, glueing, screwing, stapling, nailing, drilling oh my. I now know why some just buy the products already made...


----------



## Skylinestar

Is it bad to place bookshelf speaker on the floor? Will it cause comb filtering? Will it be better if it is placed on a stand?

 
 


One more thing..please comment on RT60 in my 15x25x9 room. Currently, I only have 4 pieces of 6" basstraps straddling the front wall left and right corners and the sidewall to floor corners.


----------



## blazar




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/10110#post_24574095
> 
> 
> Is it bad to place bookshelf speaker on the floor? Will it cause comb filtering? Will it be better if it is placed on a stand?
> 
> 
> 
> 
> 
> One more thing..please comment on RT60 in my 15x25x9 room. Currently, I only have 4 pieces of 6" basstraps straddling the front wall left and right corners and the sidewall to floor corners.



Those speakers appear to be reasonable on the floor... You can grab some telephone books and raise them to see if you like it better. Raising them to ear level will subjectively sound better in most circumstances I think.


----------



## Timoxx4




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10110#post_24571519
> 
> 
> I am not sure the tests are right. The ETC looks kind of strange. Zero ms should be at zero db and then it should taper off.



Oh. I don't know why that might be. The tests where done as per usual so not real sure what might be the cause of the strange ETC readings ? The other graphs look ok so not sure why this one would be off if the others are right ?


I do have 200ms of delay added in to my AVR for lip sync. Would this be the cause of the odd ETC graph maybe ?


----------



## fotto




> Quote:
> Originally Posted by *Timoxx4*  /t/255432/acoustical-treatments-master-thread/10110#post_24574477
> 
> 
> Oh. I don't know why that might be. The tests where done as per usual so not real sure what might be the cause of the strange ETC readings ? The other graphs look ok so not sure why this one would be off if the others are right ?
> 
> 
> I do have 200ms of delay added in to my AVR for lip sync. Would this be the cause of the odd ETC graph maybe ?



I'm pretty sure that's the root cause. If you generate a spectrogram from your sub measurement you'll notice that the SPL level really starts kicking in around 200ms vs. 0 ms where it should be. Will most likely affect presentation of ETC as well as waterfall.


----------



## matthewa

Hi could some tell me or point me to the importance of treating for SBIR for LCR


----------



## mtbdudex




> Quote:
> Originally Posted by *matthewa*  /t/255432/acoustical-treatments-master-thread/10110#post_24576279
> 
> 
> Hi could some tell me or point me to the importance of treating for SBIR for LCR



IF you locate your LCR away from boundary surfaces such that the 1/4 wave from reflected wall is then 180 deg outta phase with the direct source you may get cancellation issues at specific freq, seen as a big dip/null when you take measurements.
http://www.avsforum.com/t/989861/the-envelope-home-theatre-2014-mike-r-mtbdudex-diy-11-3-audio-2-35-scope-130in-screen/120#post_24254936 

Have fun reading!


> Quote:
> Identify and treat your modal and SBIR - Speaker Boundary Interference Response related issues and educate yourself about different bass-absorbing techniques.
> 
> Other info: SBIR by Bryan Pape


----------



## myfipie




> Quote:
> Originally Posted by *fotto*  /t/255432/acoustical-treatments-master-thread/10110#post_24574676
> 
> 
> I'm pretty sure that's the root cause. If you generate a spectrogram from your sub measurement you'll notice that the SPL level really starts kicking in around 200ms vs. 0 ms where it should be. Will most likely affect presentation of ETC as well as waterfall.



I think you might be right.


----------



## BasementBob

Triple Leaf, Quadruple Leaf.
http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm 

(This page was done back in 2005, and references the original 1992).

BTW, the quadruple leaf wall is famously difficult to actually build in the normal world, although it was built for testing at NRC.


If you look a the STC40, STC50, STC57 walls at that above link, you'll see that the triple leaf effect is so strong that it breaks the 'more mass is good' rule of thumb. You actually get a higher soundproofing wall with less mass, if you use a double leaf system, over a triple or quadruple leaf system, even though the triple/quadruple has more mass (and money).


Although the best way to understand triple leaf is probably to watch triple weight quadruple spring experiments on YouTube, and compare the resonance frequency against the same total weight but only two weights and only three springs, and then a three degree of freedom spring-mass system (three mass, four springs, with the air as spring),
https://www.youtube.com/watch?v=lZPtFDXYQRU 
https://www.youtube.com/watch?v=6y3cBdLnnuo


----------



## James004


Hi All,

 

I am getting ready to build a few panels for Bass traps and for reflection points. I have a few questions that I can't seem to find the answers to. I am sure they are there. But my head is starting to spin with the information overload. So I hope you all don't mind some newb questions being asked.

 

I have purchased some 2"X2'X4' Roxul AFB so I will start with that. But It may not be enough. So I may go to my local Lowes and pick up some of the safe and sound 5.5"x23"x4' or the 3" to double up and use that for the bass traps instead of a double layer of the 2" AFB. Would that be better for the bass traps? Would the two layers of 2" have been enough? What is considered to be the minimum thickness for good performing  bass trap panels?

 

That aside. My real questions are regarding loose fibers and Kraft Paper facing. When I want to make the broad band panels. In order to prevent loose fibers in the living room. Would it be ok to bag the batts in a 55 gal drum liner that is 1 mil thick? Without hampering its ability as a broadband absorber. This would be for first reflection and rear wall for primarily 2 channel listening. I think the rear wall should be broadband. Is that  correct? Then for the bass traps. I don't have any Kraft paper. But I am not totally sure what it actually is and where to get it. But I do have some 12" or 16" painter's masking rolls. However that material is thin. Would it be ok to use one or two layers of that then put the faced bat in a 1 mill drum liner? Would I be better off getting the 6 mill poly and wrap the entire batt with that? Does wrapping the entire batt do any harm? I really don't like the idea of loose fibers flying around.

 

Regards,

James


----------



## myfipie

"I have purchased some 2"X2'X4' Roxul AFB so I will start with that. But It may not be enough. So I may go to my local Lowes and pick up some of the safe and sound 5.5"x23"x4' or the 3" to double up and use that for the bass traps instead of a double layer of the 2" AFB. Would that be better for the bass traps? Would the two layers of 2" have been enough? What is considered to be the minimum thickness for good performing bass trap panels?"



4" is minimum but if you can make them thicker then do so. Better yet fill the whole corner.. Something like the following.
http://www.gikacoustics.com/product/gik-acoustics-soffit-bass-trap/ 


"That aside. My real questions are regarding loose fibers and Kraft Paper facing. When I want to make the broad band panels. In order to prevent loose fibers in the living room. Would it be ok to bag the batts in a 55 gal drum liner that is 1 mil thick? Without hampering its ability as a broadband absorber. This would be for first reflection and rear wall for primarily 2 channel listening. I think the rear wall should be broadband. Is that correct? Then for the bass traps. I don't have any Kraft paper. But I am not totally sure what it actually is and where to get it. But I do have some 12" or 16" painter's masking rolls. However that material is thin. Would it be ok to use one or two layers of that then put the faced bat in a 1 mill drum liner? Would I be better off getting the 6 mill poly and wrap the entire batt with that? Does wrapping the entire batt do any harm? I really don't like the idea of loose fibers flying around."


That is a lot of questions, but generally it is fine to put in bags but not for any of the early reflection points.
http://www.gikacoustics.com/video-early-first-reflection-points/ 

Keep in mind that when a trap is LARGE (like the above link) you do want to try to to not compress the material. Not a deal breaker, but you do want it as loose as possible.


----------



## James004




> That is a lot of questions, but generally it is fine to put in bags but not for any of the early reflection points.
> http://www.gikacoustics.com/video-early-first-reflection-points/
> 
> Keep in mind that when a trap is LARGE (like the above link) you do want to try to to not compress the material. Not a deal breaker, but you do want it as loose as possible.


Thanks for your reply. I was hopping since the bags are only 1 mill thick. That there effect would be negligible.

 

Are most of you not concerned about loose fibers in your living space? In my minds eye. I keep thinking of every bass thump pushing a puff of particle laden air in to the room. Is this not the case? Could anything else be done to avoid this? How about spraying the bats with some watered down latex paint or shellac?


----------



## myfipie

Bass traps are not going to puff things into the air. If they are covered in fabric that is more then enough. I have never had fiberglass dust show up.


----------



## CheYC

Is it preferred to have bass traps go all the way down to the floor? For exampe, if I have 3 inch high molding and just start the bass trap there and go up, is that OK, or should you really go full length?


----------



## myfipie




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10140#post_24588226
> 
> 
> Is it preferred to have bass traps go all the way down to the floor? For exampe, if I have 3 inch high molding and just start the bass trap there and go up, is that OK, or should you really go full length?



I would not worry about 3", but yes you do want to cover as much of the corner as possible. Not only wall to wall corners, but ceiling to wall and floor to wall corners around the room.
http://www.gikacoustics.com/mounting-bass-traps-corners/


----------



## jlpowell84

I AM GOING TO BUY SOME BASS TRAP INSULATION TONIGHT. 4 INCH PANELS ARE ROXUL AFB BUT I UNDERSTAND PINK FLUFFY IS THE BEST FOR BASS TRAPS OR ANYTHING OVER 9 INCHES THICK REALLY. THIS IS THE SAME STUFF CORRECT? LOWES SEEMS TO HAVE THE RIGHT QUANTITIES I NEED

http://www.lowes.com/pd_177781-1722-B390_4294925567__?productId=3141353&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FgoToProdList%3Dtrue%26Ns%3Dp_product_qty_sales_dollar|1&facetInfo= 


MY TRAPS WILL BE 15X15 SOFFIT TRAPS


i PLAN ON GETTING THE APPROXIMATELY 9 AND 6 INCH OPTION THAT ARE EACH 15 INCHES WIDE.


----------



## James004


Can anyone give me a source for the Kraft paper that is being used on the face of the bass traps. I thought that Lowes was supposed to have it. But they only had the very thin painters masking rolls that are up to 18" wide. Or they had heavy weight contractor paper in 36" rolls. Similar to the "peach paper" used under wood floors. Only it was brown. Are either of those the correct stuff? If not were can I buy some?

 

James


----------



## mtbdudex




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10140#post_24589115
> 
> 
> Can anyone give me a source for the Kraft paper that is being used on the face of the bass traps. I thought that Lowes was supposed to have it. But they only had the very thin painters masking rolls that are up to 18" wide. Or they had heavy weight contractor paper in 36" rolls. Similar to the "peach paper" used under wood floors. Only it was brown. Are either of those the correct stuff? If not were can I buy some?
> 
> 
> James


I used the thick kraft paper because it's what I had on hand, a whole roll of it, the 36" roll stuff you mentioned.

6mil thick plastic is perfectly fine also, if I did not have the kraft paper already I'd use the 6mil plastic.


----------



## BIGmouthinDC

My local Home Depot has a self service roll of kraft paper for wrapping items for transport. I would think enough for a bass trap if you bought a petunia.


----------



## jlpowell84

Hey guys, check out my ETC graph from a mock test of a ceiling panel over an intrusive light fixture...

http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/9390#post_24590155


----------



## Francky


Is this stuff good for bass traps and first reflection points? Roxul comfort board IS.


----------



## Francky




----------



## Francky




----------



## Francky


I'm trying to post specs but it doesnt work


----------



## James004




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10140#post_24589302
> 
> 
> My local Home Depot has a self service roll of kraft paper for wrapping items for transport. I would think enough for a bass trap if you bought a petunia.


I would not mind doing that for a four foot piece. But to pull 16' off the roll.....

 

Does the thickness of the paper really not mater? Why is 6 mil plastic advised vs any plastic you have laying around?

 

In hind site I suppose I should have purchased the 6mil plastic. But It just seemed wasteful to buy a 100' x 20' roll for $23.

 

I see Office Depot stocks kraft paper. But I don't have one local. Where is everyone getting there kraft paper?


----------



## djhamp




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10140#post_24591281
> 
> 
> 
> I would not mind doing that for a four foot piece. But to pull 16' off the roll.....
> 
> 
> Does the thickness of the paper really not mater? Why is 6 mil plastic advised vs any plastic you have laying around?
> 
> 
> In hind site I suppose I should have purchased the 6mil plastic. But It just seemed wasteful to buy a 100' x 20' roll for $23.
> 
> 
> I see Office Depot stocks kraft paper. But I don't have one local. Where is everyone getting there kraft paper?



Yeah, I am sure that would go over well!

I got a big roll at Menards - it was in the painting section


----------



## Nick in Manitou

I would think that if you asked the folks in the loading area at Home Depot if you could buy 16' of the paper they have there for customers to use for loading their vehicles, they would probably ask you how much you wanted and tell you to go ahead and take it.


A number of years ago, they had some plastic envelopes sort of things so people could keep drywall from getting rained on. I needed just that sort of thing for a project I was doing. I asked them if I could buy one, and they said, just take it! I am sure that it cost the store only a few cents, but I couldn't take it without asking permission.


It would be worth a try.


----------



## CheYC

So I just pre-ordered some Roxul Safe n' Sound 24" from Lowes, going to build some acoustic panels based on various tutorials I've seen out there. Given my odd room, I have some proposed placements for the panels (see below):


Red = Screen, Blue = couch, black boxes = speakers, gray box = sub, green arrows are proposed placements of panels, with the one in the middle being on the ceiling.

 


So I have a few questions:

- Obviously there is no wall on the left side of the room as there is on the right, I was thinking about putting a freestanding panel there (where the question mark is), are there any DIY freestanding tutorials out there? I haven't seen them...

- Since I'll have enough roxul for eight panels, would it be worth stacking two panels on top of each other in each of the front corners?


----------



## BIGmouthinDC

If you can't get some ideas here you are not trying: https://www.google.com/search?site=&tbm=isch&source=hp&biw=1536&bih=778&q=free+standing+wall+panels&oq=free+standing+wall+&gs_l=img.1.1.0l10.2042.7495.0.10794.19.14.0.5.5.0.168.1167.12j2.14.0....0...1ac.1.40.img..1.18.1094.UPBr_0U4mTQ


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10140#post_24589302
> 
> 
> My local Home Depot has a self service roll of kraft paper for wrapping items for transport. I would think enough for a bass trap if you bought a petunia.


Would house wrap work?


----------



## BIGmouthinDC

I will need to speak to the petunia


----------



## jlpowell84

So for my 15x15 soffit traps should I be using some kraft paper to get the membrane effect? That is what I read in Ethan's book. I plan on using pink fluffy 15x9.25 and just doubling it up with 15 inch plywood ends and four 1x2's for vertical support. I have the black microsuede fabric from ATS accoustics that has reflective properties above 1,000hz. you can't blow through it hardly at all. So I won't be over deading


----------



## myfipie




> Quote:
> Originally Posted by *jlpowell84*  /t/255432/acoustical-treatments-master-thread/10140#post_24588474
> 
> 
> I AM GOING TO BUY SOME BASS TRAP INSULATION TONIGHT. 4 INCH PANELS ARE ROXUL AFB BUT I UNDERSTAND PINK FLUFFY IS THE BEST FOR BASS TRAPS OR ANYTHING OVER 9 INCHES THICK REALLY. THIS IS THE SAME STUFF CORRECT? LOWES SEEMS TO HAVE THE RIGHT QUANTITIES I NEED
> 
> http://www.lowes.com/pd_177781-1722-B390_4294925567__?productId=3141353&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FgoToProdList%3Dtrue%26Ns%3Dp_product_qty_sales_dollar|1&facetInfo=
> 
> 
> MY TRAPS WILL BE 15X15 SOFFIT TRAPS
> 
> 
> i PLAN ON GETTING THE APPROXIMATELY 9 AND 6 INCH OPTION THAT ARE EACH 15 INCHES WIDE.



Roxul or the pink fluffy stuff will work for the soffits.


----------



## jlpowell84




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10140#post_24595740
> 
> 
> Roxul or the pink fluffy stuff will work for the soffits.



According to the porous calculator fluffy is better at lower frequencies, especially at 15 inches thick. So I built two of them last night. I can tell an audible reduction in decay time. It's already pretty good. I put a couple pics on the REW thread and even more for all the JTR guys on the JTR speaker thread.


----------



## myfipie

Care to post the REW file?


----------



## jlpowell84




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10140#post_24595821
> 
> 
> Care to post the REW file?



Absolutely I will tonight. I havn't began my intense thorough measurements yet but a 'hold in place' panel and quick sweep of the 1st reflection point on my ceiling was drastically awesome! Also I can't wait to see what the bass traps have done.


----------



## Frosteh

Hi all, I'm looking to do some acoustic treatment in my small theater and am looking for some advice. The goal is to make it sound as good as possible without Audyssey, then use Audyssey if I feel it's necessary. All panels except the corner bass trap are planned to be 2" right now with a 2" gap between it and the wall. The bass trap is 4". All using Rockboard 60. The thin panels above the screen are angled against the corner. My subwoofer is a JBL 4645C; it's massive and has ridiculous output. It sounds very clean right now and I haven't noticed any boomy sounds, but that doesn't mean it couldn't sound better.


Here is the room right now, w/o treatment:
 


Here is my proposed treatment (red = acoustic panel, blue = speaker, yellow = screen):
 


First: is this a good layout to start? I can't really treat the hobbit closet and can't put a panel in the corner with the gap and the door.


Second: how thick should ceiling tiles be? I'm on a budget and was planning on those only being 2". I'll make them thicker if that would make a big difference in response.


Third: How else can I do some bass trapping? I can move the subwoofer under the speaker in the rear corner and put a big trap (like GIK monster trap) on the wall right there under the projector (projector is on the back wall on a shelf above the sub).


----------



## myfipie




> Quote:
> First: is this a good layout to start? I can't really treat the hobbit closet and can't put a panel in the corner with the gap and the door.



You are going to need a lot more bass trapping in corners. Keep in mind that you not only have wall to wall corners but also ceiling to wall and floor to wall corners around the room.
http://www.gikacoustics.com/mounting-bass-traps-corners/ 


> Quote:
> Third: How else can I do some bass trapping? I can move the subwoofer under the speaker in the rear corner and put a big trap (like GIK monster trap) on the wall right there under the projector (projector is on the back wall on a shelf above the sub).



The wall behind where you sit is pretty important to treat. I would plan on covering as much of that area as you can with something thick. Like you said, along the lines of the Monster Trap.


For the ceiling, if you can swing it I would use 4" panels with a air gap. It will make a difference.


----------



## Nightlord

Make back wall into acustically semi-transparent absorber and you'll get the material out in a position where it can really do something. If you can make it a foot thick, even better.


----------



## coolgeek




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10140#post_24620043
> 
> 
> You are going to need a lot more bass trapping in corners. Keep in mind that you not only have wall to wall corners but also ceiling to wall and floor to wall corners around the room.
> http://www.gikacoustics.com/mounting-bass-traps-corners/
> 
> The wall behind where you sit is pretty important to treat. I would plan on covering as much of that area as you can with something thick. Like you said, along the lines of the Monster Trap.
> 
> 
> For the ceiling, if you can swing it I would use 4" panels with a air gap. It will make a difference.



Speaking of Bass traps, I was wondering if I could use the riser as a giant trap? My riser is 13 inch high. However, I am not sure how the 'bass' could get under the riser to begin with. The front row seats are leaning against the riser so blocking any holes i put there.


On a separate note: I have 4 feet of space behind the AT screen where i place all my speakers. I can turn that back into a giant trap with lots of RockWool. However, I see some people suggest placing a 'false wall' enclosing the speakers. However, if i did that, then all the 'absorbers i place behind that would be useless right?


----------



## coolgeek

What are pink fluffy stuff? What's their proper name so i can try to find them in my country.


Are they fiberglass insulation? Like such? http://www.alibaba.com/product-detail/Glasswool-Insulation_10838035.html 


And should i use them instead of Rockwool 80kg/m3?


----------



## bpape

Bass will go through the seating. If you want it broadband (I would) make sure the joists run front to back so you can cut larger holes in the front face and put carpet over it. That gives a lot of very nice deep absorption. If you want to limit it to bass/lower mids, you can use a limp membrane on the inside of the hole - something like pond liner works well.


The false wall is purely studs and fabric - nothing with any mass. That false wall would hold the AT screen. Generally maybe 2" of absorption up front along with more broadband type bass absorbers would be good. If you have SBIR problems, then you might want to go a little thicker on the front.


----------



## myfipie

[QUOTEOn a separate note: I have 4 feet of space behind the AT screen where i place all my speakers. I can turn that back into a giant trap with lots of RockWool. However, I see some people suggest placing a 'false wall' enclosing the speakers. However, if i did that, then all the 'absorbers i place behind that would be useless right?][/QUOTE]


No it would not be wasted. You could think about soffit mounting the speakers at that point, but I would recommend you work with a designer to make sure it is right.


----------



## coolgeek




> Quote:
> Originally Posted by *bpape*  /t/255432/acoustical-treatments-master-thread/10170#post_24620710
> 
> 
> Bass will go through the seating. If you want it broadband (I would) make sure the joists run front to back so you can cut larger holes in the front face and put carpet over it. That gives a lot of very nice deep absorption. If you want to limit it to bass/lower mids, you can use a limp membrane on the inside of the hole - something like pond liner works well.



I mean, i'll have a 3 seater 'leather' recliners that is leaning right against the riser (with no gap left either on the left or right as its exactly the same size). Would bass still get thru? And how big a hole should i cut in there?


> Quote:
> The false wall is purely studs and fabric - nothing with any mass. That false wall would hold the AT screen. Generally maybe 2" of absorption up front along with more broadband type bass absorbers would be good. If you have SBIR problems, then you might want to go a little thicker on the front.



It's not just fabric.. this is what i mean.. something to cover all the speakers...


It's probably plywood behind for those acoustic foam to be pasted on:

 


If i had that.. then the whole 2 extra feet behind with my Rockwool, etc would be useless right?


----------



## bpape

Then remove the plywood and use the real front wall (assuming it's not structural and is isolated behind.) The false wall is in front of the speakers only. That shoudl be the only false wall you have.


----------



## Frosteh




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10140#post_24620043
> 
> 
> You are going to need a lot more bass trapping in corners. Keep in mind that you not only have wall to wall corners but also ceiling to wall and floor to wall corners around the room.
> http://www.gikacoustics.com/mounting-bass-traps-corners/
> 
> The wall behind where you sit is pretty important to treat. I would plan on covering as much of that area as you can with something thick. Like you said, along the lines of the Monster Trap.
> 
> 
> For the ceiling, if you can swing it I would use 4" panels with a air gap. It will make a difference.



Glenn, would you recommend moving my subwoofer to the back right corner then? It's an 8ft^3 box and is too tall to keep where it is and put a panel on the wall. I can move it onto its side (it's front firing so it doesn't matter) and put a big trap in the rear right behind the couch. What I'd like to avoid, though, is having the bass sound boomy by moving it into the corner, thus requiring more treatment. Right now it's very clean and I don't have any treatment.


----------



## Nightlord




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/10170#post_24620793



If those speakers standing on the front arch are supposed to be there, then I do hope you remember to add the appropriate timedelay on their signals...


----------



## BIGmouthinDC

I have a feeling those are his surrounds, I have 6 in transit for a project.


----------



## coolgeek




> Quote:
> Originally Posted by *bpape*  /t/255432/acoustical-treatments-master-thread/10170#post_24620818
> 
> 
> Then remove the plywood and use the real front wall (assuming it's not structural and is isolated behind.) The false wall is in front of the speakers only. That shoudl be the only false wall you have.



I uderstand what you're saying. That's what I planed to do in the beginning.


However, after talking to a THX certified guy, he says the false 'wall' that wraps all the front speakers will do wonders to your sound (as there aren't reflected sound coming from the back wall.


Thus, the dilemma... do the false wrapped front wall and loses my giant bass trap behind or have the giant bass trap but sacrifice the 'sound quality'.


----------



## lbrown105




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/10170#post_24623322
> 
> 
> I uderstand what you're saying. That's what I planed to do in the beginning.
> 
> 
> However, after talking to a THX certified guy, he says the false 'wall' that wraps all the front speakers will do wonders to your sound (as there aren't reflected sound coming from the back wall.
> 
> 
> Thus, the dilemma... do the false wrapped front wall and loses my giant bass trap behind or have the giant bass trap but sacrifice the 'sound quality'.


wouldn't the best option to have the front false wall wrap the speakers and be an absorbant bass trap? I am re doing mine now and considering the following moving from the outside wall into the room as follows; outside rigid wall, 6" air gap, 16" pink fluffy, then 4" acoustimac eco panels flush with the edge of the speakers. My main question is, are the bass panels in front of the PF or do the negate some of their absorbant efficiency in that configuration?


----------



## BasementBob




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/10170#post_24620793



I hope your speakers are designed for wall mount, or you're using equalization to rebalance them.


I did some experiments back in 2006 with wall baffels (wood around speakers flush with the face), and insulated wall baffles (2" of rigid rockwool instead of wood), using speakers that are intended to be free in the room, without equalization, and was less than happy with the baffles. From all the hoopla, I had been expecting really great things, beyond not having to dust the tops of my speakers.

http://www.bobgolds.com/Baffel/home.htm 


Certainly you're not alone -- lots of experts baffle their speakers for one reason or another, both in the home theatre and mixing studio & movie theatre world.


----------



## Skylinestar

 http://www.avsforum.com/t/1398472/acoustic-treatments-for-an-all-concrete-room#post_24622586 


Please assist ^. Bass trapping help required.


----------



## coolgeek




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10170#post_24623629
> 
> 
> I hope your speakers are designed for wall mount, or you're using equalization to rebalance them.
> 
> 
> I did some experiments back in 2006 with wall baffels (wood around speakers flush with the face), and insulated wall baffles (2" of rigid rockwool instead of wood), using speakers that are intended to be free in the room, without equalization, and was less than happy with the baffles. From all the hoopla, I had been expecting really great things, beyond not having to dust the tops of my speakers.
> 
> http://www.bobgolds.com/Baffel/home.htm
> 
> 
> Certainly you're not alone -- lots of experts baffle their speakers for one reason or another, both in the home theatre and mixing studio & movie theatre world.



Thats right. It's called baffles. My english isn't that good and I was struggling to say what I mean.


But you have a point. A solid baffle could be bad for some speakers. Mine are all sealed so they should be fine. The idea is simple. With a baffle sound doesn't get reflected from the bavk wall and muddles things up. I know thx certified cinemas does that. However in my case I have the orbit shifter which puts out some serious bass and my theater is essentially a concrete bunker and I need as much bass traps as possible and the 4 feet behind the screen is my biggest space available.


----------



## coolgeek




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/10170#post_24623589
> 
> 
> wouldn't the best option to have the front false wall wrap the speakers and be an absorbant bass trap? I am re doing mine now and considering the following moving from the outside wall into the room as follows; outside rigid wall, 6" air gap, 16" pink fluffy, then 4" acoustimac eco panels flush with the edge of the speakers. My main question is, are the bass panels in front of the PF or do the negate some of their absorbant efficiency in that configuration?



Hmmm not using a solid baffle is an excellent idea. Solves 2 problems for me. High freequencies reflexion and bass traps.


----------



## nickbuol




> Quote:
> Originally Posted by *Nightlord*  /t/255432/acoustical-treatments-master-thread/10170#post_24621298
> 
> 
> If those speakers standing on the front arch are supposed to be there, then I do hope you remember to add the appropriate timedelay on their signals...



That isn't his theater. Those are the 6 surround channels just placed up front for comparison to the other speakers. There is a build thread here called "The Savoy" that is where he grabbed that photo from.


----------



## coolgeek




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/10170#post_24624459
> 
> 
> That isn't his theater. Those are the 6 surround channels just placed up front for comparison to the other speakers. There is a build thread here called "The Savoy" that is where he grabbed that photo from.



Exactly right and I wanted to copy this baffle design but still be able to trap bass behind it


----------



## lbrown105




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/10170#post_24624486
> 
> 
> Exactly right and I wanted to copy this baffle design but still be able to trap bass behind it


I'll have pics of what I am going to try in about two weeks. Plan on measurements before and after too. I'll post it when I have it.


----------



## coolgeek




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/10170#post_24624501
> 
> 
> I'll have pics of what I am going to try in about two weeks. Plan on measurements before and after too. I'll post it when I have it.



Wonderful. Pm me please with results


----------



## Nightlord




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/10170#post_24624459
> 
> 
> That isn't his theater. Those are the 6 surround channels just placed up front for comparison to the other speakers. There is a build thread here called "The Savoy" that is where he grabbed that photo from.



Ok. Cool in both regards then. Question withdrawn.


----------



## Jmstreithorst

Hi there, hope I can get some insights from the folks on this forum ( also hope I am on the right thread.


I am on the final stages of remodeling my new flat )and I am taking part of the livingroom space to setup my hometheater and stereo listening area. As the atea will be fully visible from the livingroom, decor is an issue.


As the HT area is open to the actual living room and there are some oddities like pilars and etc I am not sure how to calculate de standing waves, how to deal with them and (more importantly) do so without ending up in a divorce court due to messing up with the decor.


When it comes to equipment, it is as follows:


Left and Right main: BW 802d2

Center: HTM2

Suround: SCM1s

Bryston 9B (yeah, they are relly old)

Oppo 105D

Rega RP 3

Near Future ( Classe CT 2300 + a surpund high TBD)


Floor is on wood and closed varanda (hope it is clear in the plant) is in marble.


On the short wall (3,63m or 12 ft) there will be a small bookcse with LPs and CDs, enclosed equipment rack and a flat Samsung 75F8000. On the long wall (5.75 meters/ 19ft or 8.2 meters/27 ft, depending on wether you take into account the varanda) there will also be a bookcase with odd shapes (with books nd objects).


The back wall has venetian wood light stoppers ( which might act as difusers).


The othe long wall (inflomt of the bookcase is open to the livingroom.


This is probably very confusing but, hopefully, withe the palnt and sowings of the bookcases it should become clearer.


I am very sorry for the long post, but this is realy taxing for me.


Any odeas on how to deal with modes, resonance and etc?


In the next post I will post the plant, drwing and etc.


----------



## Jmstreithorst


These are the drawings. Thanks in advance for any help and advice. I know this might be to much to ask (almost a consultant's job).

 

Whole flat plant. HT are is in the middle left.



 

Plant of the HT with the book cases (it is rotate 90 degrees to the left in ration to the abobe plant. The BW 802D2 will be in the short wall.



Short wall book case. Flat TV will be in the middle.

 



 

 

Long wall book case layout:



 

Venetian that (I hope)  will act as diffusers in the back wall


----------



## sdurani




> Quote:
> Originally Posted by *Jmstreithorst*  /t/255432/acoustical-treatments-master-thread/10170#post_24629111
> 
> 
> The BW 802D2 will be in the short wall.


That will result in a soundstage that is not symmetrical from left to right (wall/bookcase on right side, opening on left side). Can you put your B&W speakers on the long wall?


----------



## James004




> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/10170#post_24629202
> 
> 
> 
> That will result in a soundstage that is not symmetrical from left to right (wall/bookcase on right side, opening on left side). Can you put your B&W speakers on the long wall?


 

I have a similar situation. Only the right side is a wall with a window and the left side is an 8' opening. Is there anything that could be done to improve the situation?

 

James


----------



## sdurani




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10170#post_24629543
> 
> 
> Only the right side is a wall with a window and the left side is an 8' opening. Is there anything that could be done to improve the situation?


If you want symmetry, put enough absorption on the right side to mimic the 8' opening on the left side.


----------



## Jmstreithorst




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/10170#post_24629202
> 
> 
> That will result in a soundstage that is not symmetrical from left to right (wall/bookcase on right side, opening on left side). Can you put your B&W speakers on the long wall?



Unfortunately no. I intend to use the books as defractors and absorbers. The big void in the middle will be covered by a painting. My idea is to put absorvive material on the wall and under the painting...


Now, that is another question; will books absorb or defract? And does defraction help?


----------



## coolgeek




> Quote:
> Originally Posted by *Jmstreithorst*  /t/255432/acoustical-treatments-master-thread/10170#post_24630045
> 
> 
> Unfortunately no. I intend to use the books as defractors and absorbers. The big void in the middle will be covered by a painting. My idea is to put absorvive material on the wall and under the painting...
> 
> 
> Now, that is another question; will books absorb or defract? And does defraction help?



My room is built like a library.. with zero treatments... and the acoustics are naturally fantastic.. i am sure with proper treatment, it will be better, but even now, it's great... !!!


----------



## Jmstreithorst

That looks great! I love the " library look". My wife actually had a used bookstore for a few years. My main problem is that the left wall in none existant. My guess/hope is that if the right side book case and painting can have enough book and absorbents I might rebalance the aound stage. But how????


----------



## coolgeek




> Quote:
> Originally Posted by *Jmstreithorst*  /t/255432/acoustical-treatments-master-thread/10170#post_24630318
> 
> 
> That looks great! I love the " library look". My wife actually had a used bookstore for a few years. My main problem is that the left wall in none existant. My guess/hope is that if the right side book case and painting can have enough book and absorbents I might rebalance the aound stage. But how????



I wouldn't worry too much about it.. it is what it is... perhaps you can hang a curtain there... and pull the curtain shut when you want to listen to music or watch a movie...


Also, if you have 'wave guide' speakers, i don't think it matters that much... (bass would escape for sure).


Speaking of library.. my heaven is to live in a library.. that's why i build my room like a library...







I spent most of my younger days hunting books in old, decrepit bookstores...


----------



## Jmstreithorst

Are there any quality pictures that act as acoustic tretment?


----------



## ellisr63




> Quote:
> Originally Posted by *Jmstreithorst*  /t/255432/acoustical-treatments-master-thread/10170#post_24630896
> 
> 
> Are there any quality pictures that act as acoustic tretment?



Look here... http://www.avsforum.com/t/1316623/diy-custom-printed-movie-poster-acoustic-panels-cheap


----------



## myfipie




> Quote:
> Originally Posted by *Jmstreithorst*  /t/255432/acoustical-treatments-master-thread/10170#post_24630896
> 
> 
> Are there any quality pictures that act as acoustic tretment?



See the following.
http://www.gikacoustics.com/product/gik-artpanel-acoustic-panels/ 


Shelving and books may help break up the upper frequencies a bit (better then a flat wall) but is not a diffusor.
http://www.gikacoustics.com/video-how-diffusion-works/ 
http://www.gikacoustics.com/how-diffusion-works/


----------



## coolgeek

Here's a strange question..


I want to turn the entire front stage of my home theater to absolute black (or as black as possible) up to 4-5 feet from the screen. For the ceiling and sides i was thinking of using the black velvet from SemourAV. The problem is, i am also using the ceiling space as bass trap / sound absorbers so will be placing rockwool up to 1 feet thick. Would the black velvet work in this regards? Or do i need other cloth materials?


Also, my screen is 20-22 inches off the ground, and i am placing my subwoofers on the ground behind the screen so i need a black acoustic material to cover the bottom part of the screen. Black velvet will block too much sound i presume, so i am thinking of either using speaker cloth or the black backing that SemourAV sells. Which is better in terms of blackness and acoustics properties?


----------



## Rjloper9




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/10200_100#post_24634308
> 
> 
> Here's a strange question..
> 
> 
> I want to turn the entire front stage of my home theater to absolute black (or as black as possible) up to 4-5 feet from the screen. For the ceiling and sides i was thinking of using the black velvet from SemourAV. The problem is, i am also using the ceiling space as bass trap / sound absorbers so will be placing rockwool up to 1 feet thick. Would the black velvet work in this regards? Or do i need other cloth materials?
> 
> 
> Also, my screen is 20-22 inches off the ground, and i am placing my subwoofers on the ground behind the screen so i need a black acoustic material to cover the bottom part of the screen. Black velvet will block too much sound i presume, so i am thinking of either using speaker cloth or the black backing that SemourAV sells. Which is better in terms of blackness and acoustics properties?



this thread here may help some http://www.avsforum.com/t/1465053/black-theater-improvment-thread-once-you-go-black-you-never-go-back/0_100


----------



## Rjloper9

I have a space, when finished, that would measure approximately 13'6" in length and anywhere between 16'-20' in width. There is large ductwork running nearly down the center of my space. I have been thinking about opting for the wide layout opposed to the lengthwise layout for this reason. The thinking is it will allow me to keep more of my 8' ceiling space instead of having a 6'8" tall cave of a theater. Maybe a 6'8" cave run lengthwise would sound better?


If I go with the wide layout then, acoustically speaking, which of these wide room layouts would work better?


This one...?
 
 


or this one...?
 
 


I plan on using the fabricmate track/panel system on the walls. I'm perplexed and need some input. Thanks!


----------



## sdurani




> Quote:
> Originally Posted by *Rjloper9*  /t/255432/acoustical-treatments-master-thread/10200#post_24637656
> 
> 
> Maybe a 6'8" cave run lengthwise would sound better?


More options if you run lengthwise.


> Quote:
> Originally Posted by *Rjloper9*  /t/255432/acoustical-treatments-master-thread/10200#post_24637656
> 
> 
> If I go with the wide layout then, acoustically speaking, which of these wide room layouts would work better?


I would do the first one, so that the door is not in the front half of the room, allowing me to keep the front soundstage symmetrical from left to right.


----------



## CheYC

I have a question on building a corner bass trap, really just a check to see if this is all kosher... I'm currently thinking of buying a pack of 16"x48" safe n' sound and cutting each individual piece into six 16"x16"x22.5" inch triangles, a whole package should give me 48 triangles with a total thickness of 12 feet. So, does this all sound correct? I notice not too many people use the safe n' sound for bass trapping it seems, so will I be better off with something else? It's just easiest bc they have it in stock at my local Lowes. Thanks!


----------



## James004


Now that I have my bass traps done. I am ready to move on to panels. But I have a few questions. First and foremost is regarding something that I read. It said that for first reflection points. Anything less than a 4" thick panel will do more harm than good. As it will result in a muffled sound. Due to it only being  able to absorb upper part of the spectrum leaving the bass and mids in tact. Is that true?

 

Depending on that answer. I need to keep these panels as unobtrusive as possible. I was going to do 2" thick 2'x4' panels of Roxul Safe and Sound with a 1" space behind. Would I be better off with a 3" thick panel with no space? I am trying to limit myself to 3" of protrusion into the room as to not upset my wife too much. But if it really needs to be 4" (with or without space behind?) I will have to renegotiate with here.

 

Lastly should all absorbers on the front wall have a reflective face? Or is that only for the corner traps? Then the rest of the room (side walls and back wall) should be full range (no paper face)? Is that correct. This is only for walls no saddles will be used.

 

Regards,

James


----------



## ellisr63




> Quote:
> Originally Posted by *Rjloper9*  /t/255432/acoustical-treatments-master-thread/10200#post_24637656
> 
> 
> I have a space, when finished, that would measure approximately 13'6" in length and anywhere between 16'-20' in width. There is large ductwork running nearly down the center of my space. I have been thinking about opting for the wide layout opposed to the lengthwise layout for this reason. The thinking is it will allow me to keep more of my 8' ceiling space instead of having a 6'8" tall cave of a theater. Maybe a 6'8" cave run lengthwise would sound better?
> 
> 
> If I go with the wide layout then, acoustically speaking, which of these wide room layouts would work better?
> 
> 
> This one...?
> 
> 
> 
> 
> or this one...?
> 
> 
> 
> 
> I plan on using the fabricmate track/panel system on the walls. I'm perplexed and need some input. Thanks!


The first one would be nice if you are doing a HT as it would allow you to put the speakers behind a AT screen.


----------



## Nighthawk26

I used Roxul Comfortboard IS. Mine came from Home Depot. I don't recall Lowes havin git, but I'm in Canada. The alternatice although typically more money is owens corning 703. Mine made a massive improvement, but I will also note it's not a dedicated closed theater, its more of an open space to the back, but the front is enclosed. All my speakers are behind the screen which is 24" off the wall. I basically cut each piece into 4 triangles and it worked great.


----------



## Nighthawk26

James, I'm currently having similar thoughts. Was going to use the same board I mentioned above which is 1.5" (I read 2" is avail, but not at a big box strore I could find). OR I will use layers of linacoustic. I'm still in the same boat as you trying to sort through the same things with the additional other option of linacoustic.


----------



## James004




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10200#post_24638763
> 
> 
> 
> Now that I have my bass traps done. I am ready to move on to panels. But I have a few questions. First and foremost is regarding something that I read. It said that for first reflection points. Anything less than a 4" thick panel will do more harm than good. As it will result in a muffled sound. Due to it only being  able to absorb upper part of the spectrum leaving the bass and mids in tact. Is that true?
> 
> 
> 
> Depending on that answer. I need to keep these panels as unobtrusive as possible. I was going to do 2" thick 2'x4' panels of Roxul Safe and Sound with a 1" space behind. Would I be better off with a 3" thick panel with no space? I am trying to limit myself to 3" of protrusion into the room as to not upset my wife too much. But if it really needs to be 4" (with or without space behind?) I will have to renegotiate with here.
> 
> 
> 
> Lastly should all absorbers on the front wall have a reflective face? Or is that only for the corner traps? Then the rest of the room (side walls and back wall) should be full range (no paper face)? Is that correct. This is only for walls no saddles will be used.
> 
> 
> 
> Regards,
> 
> James


Can anyone help with this? I would like to start on this tomorrow.


----------



## NicksHitachi




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10200#post_24640946
> 
> 
> 
> 
> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10200#post_24638763
> 
> 
> 
> 
> Now that I have my bass traps done. I am ready to move on to panels. But I have a few questions. First and foremost is regarding something that I read. It said that for first reflection points. Anything less than a 4" thick panel will do more harm than good. As it will result in a muffled sound. Due to it only being  able to absorb upper part of the spectrum leaving the bass and mids in tact. Is that true?
> 
> 
> Depending on that answer. I need to keep these panels as unobtrusive as possible. I was going to do 2" thick 2'x4' panels of Roxul Safe and Sound with a 1" space behind. Would I be better off with a 3" thick panel with no space? I am trying to limit myself to 3" of protrusion into the room as to not upset my wife too much. But if it really needs to be 4" (with or without space behind?) I will have to renegotiate with here.
> 
> 
> Lastly should all absorbers on the front wall have a reflective face? Or is that only for the corner traps? Then the rest of the room (side walls and back wall) should be full range (no paper face)? Is that correct. This is only for walls no saddles will be used.
> 
> 
> Regards,
> 
> James
> 
> 
> 
> 
> 
> Can anyone help with this? I would like to start on this tomorrow.
Click to expand...


4" total prob will not get your total speculars -20db. Youll probably miss the last octave before your room transitions to modal behavior but should work well above that.


Whether its better than nothing is a personal question to me but imo yes it would be significantly better than nothing.


I find specular reflections most audibly offensive in the 900-3kHz region and you should attenuate those sufficiently with any of your options.


Whether or not to leave the air gap or fill it with Roxul, it might be marginally better to fill the air gap but IMO a waste of money that could pay better dividends elsewhere.


----------



## BasementBob




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10200#post_24638763
> 
> 
> . I was going to do 2" thick 2'x4' panels of Roxul Safe and Sound with a 1" space behind.


That'll be fine. Particularly with normal drywall walls.

Pretty good for solving imaging problems.

Better than thinner alternatives you might have elsewhere in the room, like a floor full of carpet, from a wide frequency absorption point of view.


----------



## James004


Thank you both. That graph is especially helpful in solidifying in my mind the effect the different thickness plus air gap combinations make. I wonder why 3" plus air gap was left out? The Roxul AFB is fairly cheap from a supplier here in CT named Marjam. It is only $34 per 8pc bag for the 3"x2'x4'. So I am going to go with the 3" plus 1/2" air gap. Then once the initial shock wears off my wife. I bump the gap up to 1". If it will help any.

 

Regards,

James


----------



## CheYC

What are people using for an air gap, just curious? I think I seen something in the past where someone was using little round 1 inch thick felt pads as a spacer between the frame of their panels and the wall?


----------



## myfipie




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10200#post_24643193
> 
> 
> What are people using for an air gap, just curious? I think I seen something in the past where someone was using little round 1 inch thick felt pads as a spacer between the frame of their panels and the wall?



We build the air gap into ours, but I have seem people use spacers from cut wood. Does not look as nice but will work.


----------



## BasementBob




> Quote:
> Originally Posted by *James004*  /t/255432/acoustical-treatments-master-thread/10200#post_24643148
> 
> 
> I wonder why 3" plus air gap was left out?


Because you didn't ask for it.









(Yes, that's a custom graph, made today just for you)


----------



## artur9




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10200#post_24643641
> 
> 
> Because you didn't ask for it.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> (Yes, that's a custom graph, made today just for you)



That's awesome! Would you be so kind as to regenerate it to go down to 15Hz and the 3" Roxul with some air gaps? Or tell me how?


In my room, I have some "behaviour" at around 30Hz that I'm curious as to how well the Roxul can correct.


----------



## James004




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10200#post_24643641
> 
> 
> 
> Because you didn't ask for it.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> (Yes, that's a custom graph, made today just for you)


Oh! I did not realize that. Thank you very much.


----------



## Skylinestar




> Quote:
> Originally Posted by *coolgeek*  /t/255432/acoustical-treatments-master-thread/10200#post_24634308
> 
> 
> Here's a strange question..
> 
> 
> I want to turn the entire front stage of my home theater to absolute black (or as black as possible) up to 4-5 feet from the screen. For the ceiling and sides i was thinking of using the black velvet from SemourAV. The problem is, i am also using the ceiling space as bass trap / sound absorbers so will be placing rockwool up to 1 feet thick. Would the black velvet work in this regards? Or do i need other cloth materials?
> 
> 
> Also, my screen is 20-22 inches off the ground, and i am placing my subwoofers on the ground behind the screen so i need a black acoustic material to cover the bottom part of the screen. Black velvet will block too much sound i presume, so i am thinking of either using speaker cloth or the black backing that SemourAV sells. Which is better in terms of blackness and acoustics properties?


Experts in here told me that velvet has no effect on bass.


----------



## coolgeek




> Quote:
> Originally Posted by *Skylinestar*  /t/255432/acoustical-treatments-master-thread/10200#post_24649595
> 
> 
> Experts in here told me that velvet has no effect on bass.



I don't know... sounds risky... i think i'll stick to speaker cloth..


----------



## blazar

Another material that will work for acoustic transparency is sheets of performated aluminum (powder coated or painted). This might suit certain decors compared to fabric. You will need appropriate bracing and grommets to prevent vibration


----------



## Nyal Mellor




> Quote:
> Originally Posted by *blazar*  /t/255432/acoustical-treatments-master-thread/10200#post_24654211
> 
> 
> Another material that will work for acoustic transparency is sheets of performated aluminum (powder coated or painted). This might suit certain decors compared to fabric. You will need appropriate bracing and grommets to prevent vibration



Not truly acoustically transparent.. will have some rolloff >1kHz.


----------



## Nyal Mellor




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10200#post_24643193
> 
> 
> What are people using for an air gap, just curious? I think I seen something in the past where someone was using little round 1 inch thick felt pads as a spacer between the frame of their panels and the wall?



Primacoustic make some nice Offset Impalers


----------



## Archaea

I'd like to coat the entire front wall of my theater room with dampening materials making for a dead front, live rear acoustic treatment sound. I've been to a LOT of home theaters and that's my subjective favorite acoustic model.


I have a 144" 2.35:1 AT screen, with 89" ceiling height and a 218" front wall length.


Behind this projection wall is a storage room, so I'm planning to make the wall into a false wall/baffle wall.


I see this Aurlex Platfoam is recommended to coat a front baffle wall.
http://www.bhphotovideo.com/c/product/411346-REG/Auralex_PLATSHEET_PlatFoam_Isolation_Sheets.html 


I also see some people using the 12 or 24" styled foam pieces.
http://www.bhphotovideo.com/c/buy/Absorption-Panels-Fills/ci/16131/N/3992462136 


What other options do people recommend to coat a front wall with? Like most who ask for recommendations instead of just buy - I'm on a budget so "cheaper and functional" is more suitable than "expensive and best"

 
 




Here is my thread asking for suggestions in helping my room come together with a reasonable design...
http://www.avsforum.com/t/1525397/archaeas-ht-sandbox-help-me-build-a-new-multipurpose-basement-home-theater-room


----------



## Nyal Mellor




> Quote:
> Originally Posted by *Archaea*  /t/255432/acoustical-treatments-master-thread/10200#post_24663406
> 
> 
> I'd like to coat the entire front wall of my theater room with dampening materials making for a dead front, live rear acoustic treatment sound. I've been to a LOT of home theaters and that's my subjective favorite acoustic model.
> 
> 
> I have a 144" 2.35:1 AT screen, with 89" ceiling height and a 218" front wall length.
> 
> 
> Behind this projection wall is a storage room, so I'm planning to make the wall into a false wall/baffle wall.
> 
> 
> I see this Aurlex Platfoam is recommended to coat a front baffle wall.
> http://www.bhphotovideo.com/c/product/411346-REG/Auralex_PLATSHEET_PlatFoam_Isolation_Sheets.html
> 
> 
> I also see some people using the 12 or 24" styled foam pieces.
> http://www.bhphotovideo.com/c/buy/Absorption-Panels-Fills/ci/16131/N/3992462136
> 
> 
> What other options do people recommend to coat a front wall with? Like most who ask for recommendations instead of just buy - I'm on a budget so "cheaper and functional" is more suitable than "expensive and best"
> 
> 
> 
> 
> 
> 
> 
> Here is my thread asking for suggestions in helping my room come together with a reasonable design...
> http://www.avsforum.com/t/1525397/archaeas-ht-sandbox-help-me-build-a-new-multipurpose-basement-home-theater-room



Are you doing a baffle wall (solid surface) or just a false wall?


I saw your comment on PlatSheeet and Foam, maybe you saw that on the Savoy theater? My comment to everyone is don't blindly copy a design done for another room. It is critical that the overall acoustical design is balanced. Everything must be considered as a whole for proper balance. Personally I like the Auralex stuff or equivalent foam for putting on the front of a baffle wall, as it's easy to apply relative to using other materials, but you need to make sure it's balanced by the choices you make on treating the rest of the room.


----------



## Archaea

Thanks for the advice. Baffle wall is my thought. Cut out holes for the speakers in the existing wall.


----------



## lbrown105




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/10200#post_24663547
> 
> 
> Are you doing a baffle wall (solid surface) or just a false wall?
> 
> 
> I saw your comment on PlatSheeet and Foam, maybe you saw that on the Savoy theater? My comment to everyone is don't blindly copy a design done for another room. It is critical that the overall acoustical design is balanced. Everything must be considered as a whole for proper balance. Personally I like the Auralex stuff or equivalent foam for putting on the front of a baffle wall, as it's easy to apply relative to using other materials, but you need to make sure it's balanced by the choices you make on treating the rest of the room.


so what is generally better on the front wall. A solid baffle wall or a false wall built with thick absorption. I am planning the whole front wall with speakers flushmounted to 4" panels (acoustimac panels) that are 16" from the wall with pink fluffy filled int for a total of 20" of broad band absorption behind and up to flush with the speakers. Archea, if I understand what your doing is flush mount speakers with solid surface (drywall?) I don't know if one is preffered or if everyroom is different for this aspect?


----------



## Nyal Mellor




> Quote:
> Originally Posted by *lbrown105*  /t/255432/acoustical-treatments-master-thread/10200#post_24673136
> 
> 
> so what is generally better on the front wall. A solid baffle wall or a false wall built with thick absorption. I am planning the whole front wall with speakers flushmounted to 4" panels (acoustimac panels) that are 16" from the wall with pink fluffy filled int for a total of 20" of broad band absorption behind and up to flush with the speakers. Archea, if I understand what your doing is flush mount speakers with solid surface (drywall?) I don't know if one is preffered or if everyroom is different for this aspect?



There's that "generally" question again










No such thing as "generally" for high performance, only considered and engineered solutions appropriate for the room, speakers, layout and aesthetics.


----------



## CheYC

So, I'm still trying to think of creative ways to treat my basement for the massive amount of boomy bass (virtually no decay via REW), my latest idea is to hang 2'x4' 6" thick acoustic panels from the soffit so that they're basically hanging right behind the seating area (see pic below). In effect, it will kind of divide the back of the room from the front part. Any thoughts on this?


----------



## mtbdudex

Can you open up those soffits instead and make them into bass traps?

Where is your floor plan and layout posted?



Via Mikes brain/thumb interface, LLAP


----------



## CheYC




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/10200#post_24702352
> 
> 
> Can you open up those soffits instead and make them into bass traps?
> 
> Where is your floor plan and layout posted?
> 
> 
> 
> Via Mikes brain/thumb interface, LLAP



Unfortunately that soffit is where the HVAC ventilation runs, so nothing can be put in there.


I have some more pics:

 
 
 
 


Pardon the partially pinstriped wall, had water damage down there and that hasn't been repainted.


Initially I just wanted a casual hangout area to watch sports and stuff, and while I still want that to an extent, I'm starting to want more of a HT feel and setup, wish I would've had that in mind when the contractors were doing work down there, I probably would've closed the section off. I have the feeling that the opening to up the stairs is bad too, from what I hear. There's also lots of corners...


----------



## ellisr63




> Quote:
> Originally Posted by *mtbdudex*  /t/255432/acoustical-treatments-master-thread/10200#post_24702352
> 
> 
> Can you open up those soffits instead and make them into bass traps?
> 
> Where is your floor plan and layout posted?
> 
> 
> 
> Via Mikes brain/thumb interface, LLAP


That is what we are doing in our HT... Most of the soffits will be open with fiberglass stuffed inside and covered with AT material. We are doing it this way to allow the HVAC duct dampers to be accessed, run speaker wires, HDMI cables, and to work as a bass trap.


----------



## Frank D




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10200#post_24702230
> 
> 
> So, I'm still trying to think of creative ways to treat my basement for the massive amount of boomy bass (virtually no decay via REW), my latest idea is to hang 2'x4' 6" thick acoustic panels from the soffit so that they're basically hanging right behind the seating area (see pic below). In effect, it will kind of divide the back of the room from the front part. Any thoughts on this?



Yes that is a good idea. Also hang some similar 4" or 2" panels at the ceiling reflection point. A thick carpet with some under padding between the centre speaker and seating is a good idea too. Also consider acoustical panels at side reflection points of either 2" or 4" thick. Any other corners you can further use for more bass absorption is also good. I have never tried tri traps but maybe you can use those where three corners meet.


Also putting thick 6" acoustical panels behind your front speakers is good too.


----------



## CheYC




> Quote:
> Originally Posted by *Frank D*  /t/255432/acoustical-treatments-master-thread/10230#post_24703172
> 
> 
> Yes that is a good idea. Also hang some similar 4" or 2" panels at the ceiling reflection point. A thick carpet with some under padding between the centre speaker and seating is a good idea too. Also consider acoustical panels at side reflection points of either 2" or 4" thick. Any other corners you can further use for more bass absorption is also good. I have never tried tri traps but maybe you can use those where three corners meet.
> 
> 
> Also putting thick 6" acoustical panels behind your front speakers is good too.



I started with some treatments, I have 3" thick panels with air gaps behind the front speakers (see pic above) and a 3" panel on one of the side reflection points (the Yankees decorated one above), it's difficult because one side has a wall whereas the other side is open, so I might have to go freestanding. I've been thinking about the ceiling, but not sure if it will interfere with my projector, I need to check that.


----------



## Archaea

I'm looking for some solid advice on acoustical treating this front wall.


Notes:

I'm cost conscious

I have a seymour XD AT screen that covers all three speakers.

I like the dead front wall, live rear wall treatments I've heard in home theaters.

I don't care about dampening noise from this room to other rooms, just optimizing my sound in my room.

I rather like the look of the wainscoting, but am not opposed to taking it off or covering it if warranted.


pic: (excuse the mess - quick cellphone snapshot after making the baffle wall cutouts yesterday)











thread with dimmensions and other pics:
http://www.avsforum.com/t/1525397/archaeas-ht-sandbox-help-me-build-a-new-multipurpose-basement-home-theater-room 



Would some egg crate foam behind the screen be a decent start?

NRC .67
http://www.amazon.com/1-5-Acoustic-Foam-Crate-SoundProofing/dp/B005IAN7NE/ref=sr_1_40?s=musical-instruments&ie=UTF8&qid=1399915245&sr=1-40&keywords=acoustic+foam 

or NRC .75
http://www.amazon.com/2-5-Acoustic-Foam-Crate-SoundProofing/dp/B004QORA4K/ref=sr_1_47?s=musical-instruments&ie=UTF8&qid=1399915245&sr=1-47&keywords=acoustic+foam 


It seems after some additional reading that Aurlex platform is more for dampening or sound leakage...I'm not concerned with that in this project. 2 story house and I'm in the basement. You can't hear the sound upstairs where the bedrooms are enough to matter - even at current.



Stuff I have on hand that I bought off craigslist...


ten OC703 panels

a dozen rockwool panels from 2.5" through 5"

a dozen aurlex 2" 12x12 foam panels


Anything I treat on the front wall behind the projector screen either needs to be covered in black speaker cloth or be a dark gray color for light control on the AT screen. I've read that you can't effectively spray paint foam without negatively effecting treatment properties.


----------



## NicksHitachi




> Quote:
> Originally Posted by *Archaea*  /t/255432/acoustical-treatments-master-thread/10230#post_24710459
> 
> 
> I'm looking for some solid advice on acoustical treating this front wall.
> 
> 
> Notes:
> 
> I'm cost conscious
> 
> I have a seymour XD AT screen that covers all three speakers.
> 
> I like the dead front wall, live rear wall treatments I've heard in home theaters.
> 
> I don't care about dampening noise from this room to other rooms, just optimizing my sound in my room.
> 
> I rather like the look of the wainscoting, but am not opposed to taking it off or covering it if warranted.



How much room do you have behind the screen?


I'd skip the foam and opt for something like Roxul Safe-n-sound Or OC-703 or Linacoustic. The roxul is likely the cheapest and available through lowes.


Tip: If you go get a "moving package" from the post office to change your address. Inside you'll find a 10% or 20% off coupon for free which can add up to big savings if your buying say a lawnmower or lots of insulation.


Cheers.


----------



## lbrown105

Thought some of you might find a few in room measurements interesting for what is typically in the soundproofing thread.

http://www.avsforum.com/t/1531346/drop-ceiling-upgrade#post_24708749


----------



## jlpowell84

Yes, how far out is the screen? Also what is the material on the ceiling? If it is not absorbent in the best ways possible we need to deal with that. The first reflection points on the ceiling ARE THE SINGLE MOST beneficial specular reflection treatments you can do. This is not just my opinion rather I am just echoing the guys who REALLY know their stuff. Room is looking great J and exciting to see it developing. And glad you are content and happy with your 228's and not gritting down the fun money account for 215's







Anyway, for the ceiling. it looks like basic drop down material we would see in an office correct? If so that is good news because there is acoustical material that is direct drop in replacement for those panels. I believe Craig John has them but I could be mistaken. In the end it is all about the Porous calculator. This is a very easy tool to get to know and will make you a genius on what materials to use and what not to use and what thicknesses with what air gaps









http://www.acousticmodelling.com/porous.php 


Basically you enter the thickness and the "Air flow resistivity" of the insulation you wish to use click calculate and you have the absorbent coefficient! You can see what frequencies it will affect. Two things that hopefully some people who know will chime in. I believe you select random incidence every time as that means the air, or sound waves, will travel not only straight in to the insulation but from every little angle? So from above, to the side or whatever that is not directly straight in. Also to really get a good effect at absorbing that frequency you want the absorbent coefficient to be at 0.7 or above. I feel in my amateur ventures that I still get benefits lower than that but I remember that stated before.


So the front wall...I like to keep cost down as well. Never buy raw materials from an acoustic company. They up charge but I am sure you know that







I googled and found a local-ish company that was 2 hours on either side of me. I had it delivered in the end. But I got Roxul AFB which has an air flow resistivity of about 16,600. Gearslutz has a nice list somewhere of air flow resistivity numbers that can be easily found in an google search. I believe it is the most like OC 703. It is good material for reflections and not bass traps. I would say if you can find a way to attach raw OC 703 or Roxul AFB behind the screen directly on the wall perhaps with some glue? Or some way to attach it. That would keep cost minimal. I ended up getting a 14 pack of Roxul AFB that is 2x24x48 for about 60 bucks I think. It was awhile ago. too bad you are so far because I bought 4 packs of 14 sheets and didn't use it all. The main purpose of front wall treatment in respect to reflections is dealing with surround speaker reflections. And like you said it contributes to the LEDE approach. Really no reason to build pretty wood framed panels if it is just going to go behind a screen. I would say raw insulation behind your screen in between and above your LCR and then perhaps some wood framed panels on the outside where visible.


Anyway, so the purpose of treating a room MUST be scientifically approached. I beg you not to just throw up panels in your room where you think they go. The ceiling will be massively important. Find a way. I don't know the cost of the drop in pieces I read about awhile ago. Perhaps if it is overpriced then a mounting bracket of some sort could be built to receive a ceiling treatment? That is what I did. Let me know if I missed anything. Just got home off work and had a Ninkasi Microbrew and feel all over the place lol! I am off to sand and paint my Volt 10 little 12 inch cube cabinets


----------



## jlpowell84

Okay just read that behind the screen needs to be dark. Obvious now







So maybe just a quick wood frame so you could wrap in black burlap? I think 2 inches thick would be enough for behind the screen. But the numbers always say more is better! Say if you built 2 or 4 inch thick wood frames you could custom size to fit in between the L,R and center areas and above. Mounting would be easier too. Again, not sure how far out your screen will be.


In comment to toe in. Is making that LR speaker holes "slightly" bigger for a little more toe in not possible ?


----------



## myfipie

Also agree about the ceiling and also don't forget about the side walls.
http://www.gikacoustics.com/video-early-first-reflection-points/


----------



## DrPainMD

A friend of mine is building a partition wall and wants to insulate it with egg cartons(used as pink insulation) and paint the inside of the walls and studs black.


Will this help with soundproofing?


----------



## BIGmouthinDC

About as good as a placebo pain medicine, let him try it he might like it.


Now if he leaves it exposed it will absorb some high frequency sound energy in the room and perhaps that is what he is after, The room will sound different and he may think it is sound proofing. If you are talking about eggcrate foam, be aware that some brands are a fire hazard and having an entire wall covered can be an issue, remember the night club fire a few years back?


----------



## DrPainMD




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10230#post_24713193
> 
> 
> About as good as a placebo pain medicine, let him try it he might like it.
> 
> 
> Now if he leaves it exposed it will absorb some high frequency sound energy in the room and perhaps that is what he is after, The room will sound different and he may think it is sound proofing. If you are talking about eggcrate foam, be aware that some brands are a fire hazard and having an entire wall covered can be an issue, remember the night club fire a few years back?



it will all be inside the wall, so not exposed


----------



## Archaea




> Quote:
> Originally Posted by *jlpowell84*  /t/255432/acoustical-treatments-master-thread/10230#post_24712029
> 
> 
> Okay just read that behind the screen needs to be dark. Obvious now
> 
> 
> 
> 
> 
> 
> 
> So maybe just a quick wood frame so you could wrap in black burlap? I think 2 inches thick would be enough for behind the screen. But the numbers always say more is better! Say if you built 2 or 4 inch thick wood frames you could custom size to fit in between the L,R and center areas and above. Mounting would be easier too. Again, not sure how far out your screen will be.
> 
> 
> In comment to toe in. Is making that LR speaker holes "slightly" bigger for a little more toe in not possible ?



Thanks for the feedback!


If you lived closer I'd let you have a listen, minimal toe in works just fine with the JTR 228HT. It's just not something that makes much difference with these speakers in my experience. Toe in is partially to help avoid unwanted reflections against the side walls. The horn on the JTR is 60* x 40* which really cuts down on those reflections - hence not as much need for sharp toe in. I watched a bunch of tracks off the scubasteve demo disk last night and the sound was great with the speakers behind the AT screen. The picture, however, is still too washed out. I need some visual darkening treatments on the white drop ceiling as well. My last room had a black drywall ceiling, what a difference that makes with a projector!


----------



## BIGmouthinDC




> Quote:
> Originally Posted by *DrPainMD*  /t/255432/acoustical-treatments-master-thread/10240_40#post_24713299
> 
> 
> it will all be inside the wall, so not exposed



Then painting it and the studs black is an excellent idea.


----------



## DrPainMD




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10230#post_24713486
> 
> 
> Then painting it and the studs black is an excellent idea.



are you being serious or sarcastic?


----------



## Willie

I vote for sarcastic.


----------



## NicksHitachi




> Quote:
> Originally Posted by *DrPainMD*  /t/255432/acoustical-treatments-master-thread/10230#post_24713174
> 
> 
> A friend of mine is building a partition wall and wants to insulate it with egg cartons(used as pink insulation) and paint the inside of the walls and studs black.
> 
> 
> Will this help with soundproofing?



Can you elaborate on this?


Its confusing what your asking which is why your not getting a clear answer.


----------



## BIGmouthinDC

This answer should be clear, *NO* neither the eggs cartons nor the black paint will offer any sound proofing. The fact that your friend wants to paint something black inside the closed stud wall is baffling.


----------



## sdurani




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10230#post_24714865
> 
> 
> The fact that your friend wants to paint something black inside the closed stud wall is baffling.


You haven't heard the well kept secret amongst home theatre designers about black paint being one of the best sound absorbers available?


Yeah, me neither.


----------



## artur9




> Quote:
> Originally Posted by *sdurani*  /t/255432/acoustical-treatments-master-thread/10230#post_24715021
> 
> 
> You haven't heard the well kept secret amongst home theatre designers about black paint being one of the best sound absorbers available?
> 
> 
> Yeah, me neither.



Maybe it's the newly discovered Black Body Radiation principle as applied to acoustics. I think for it to work properly the wall needs to hum at the Schroeder frequency.


----------



## schmidtwi




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/10230#post_24715129
> 
> 
> Maybe it's the newly discovered Black Body Radiation principle as applied to acoustics. I think for it to work properly the wall needs to hum at the Schroeder frequency.



Hmmm, you may be onto something. Black noise is silent noise, black velvet absorbs colors and light, black holes absorb astronomical energy. Maybe there's something to this black paint absorbing sound thing....


Not looking forward to tearing down my DD/GG walls to paint the studs & inside drywall, though....


----------



## DrPainMD

Yes I know it sounds weird, but that's what he wants to do and believes it will work.


Paint behind the drywall black (inside cavity)

and use egg cartons(the ones used to hold 12 eggs) for insulation (replacing the typical pink stuff)


----------



## DrPainMD




> Quote:
> Originally Posted by *artur9*  /t/255432/acoustical-treatments-master-thread/10230#post_24715129
> 
> 
> Maybe it's the newly discovered Black Body Radiation principle as applied to acoustics. I think for it to work properly the wall needs to hum at the Schroeder frequency.


 http://www.acousticalsurfaces.com/coat-of-silence/coat-of-silence.html


----------



## DrPainMD

it still confus


> Quote:
> Originally Posted by *NicksHitachi*  /t/255432/acoustical-treatments-master-thread/10230#post_24714782
> 
> 
> Can you elaborate on this?
> 
> 
> Its confusing what your asking which is why your not getting a clear answer.




its still confusing me


----------



## nickbuol




> Quote:
> Originally Posted by *DrPainMD*  /t/255432/acoustical-treatments-master-thread/10230#post_24715754
> 
> 
> Yes I know it sounds weird, but that's what he wants to do and believes it will work.
> 
> 
> Paint behind the drywall black (inside cavity)
> 
> and use egg cartons(the ones used to hold 12 eggs) for insulation (replacing the typical pink stuff)


I will be blunt here and say that your friend is stupid and majorly uninformed about this subject. I mean the word stupid as in exactly that, uneducated to the point of having no merit in his thought on this, not that he is stupid in general. I will leave that assessment up to you. LOL. I am also being blunt because I hate it when people are mislead and then greatly disappointed in the end result. Help educate him and he will be a lot happier.


----------



## DrPainMD




> Quote:
> Originally Posted by *nickbuol*  /t/255432/acoustical-treatments-master-thread/10230#post_24715807
> 
> 
> 
> I will be blunt here and say that your friend is stupid and majorly uninformed about this subject. I mean the word stupid as in exactly that, uneducated to the point of having no merit in his thought on this, not that he is stupid in general. I will leave that assessment up to you. LOL. I am also being blunt because I hate it when people are mislead and then greatly disappointed in the end result. Help educate him and he will be a lot happier.



i will


----------



## nickbuol

Where does he live? Maybe we could organize and intervention. LOL


----------



## Aarghon

If I were him, I'd indeed put egg cartons in the wall. But they have to be full of eggs to fully absorb frequencies. It's the yolk that absorbs, not the shells


----------



## cshuff




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/10230#post_24716060
> 
> 
> If I were him, I'd indeed put egg cartons in the wall. But they have to be full of eggs to fully absorb frequencies. It's the yolk that absorbs, not the shells



.....I'm still laughing.....hard


----------



## BasementBob




> Quote:
> Originally Posted by *DrPainMD*  /t/255432/acoustical-treatments-master-thread/10230#post_24713174
> 
> 
> A friend of mine is building a partition wall and wants to insulate it with *egg cartons* (used as pink insulation) and paint the inside of the walls and studs black.
> 
> 
> Will this help with soundproofing?



Using egg cartons for acoustical purposes was actually done at one point, somewhere between WWII and the mid 1950s.

The radio announcer on the comedy/variety television show Hee Haw (1969-1989) had egg cartons on the walls in his recording booth (picture below).


"Are egg cartons any good acoustically?" came up often enough in discussions between 1980-2005, that acoustical tests were done:
http://www.acousticsfirst.com/eggc.htm 


The short answer is:

a) don't use them in your walls (soundproofing), and

b) don't use them in your room (acoustic treatment), and

c) they're good in the fridge though, at least as long as you have eggs.


----------



## DrPainMD




----------



## myfipie




> Quote:
> Originally Posted by *DrPainMD*  /t/255432/acoustical-treatments-master-thread/10230#post_24715826
> 
> 
> i tried and i dont think hes even ready to listen.
> 
> 
> and i agree with you that hes a moron



Well if this is the case then PLEASE start a thread showing pictures of what NOT to do. A little bit of humor goes a long way on the interwebs!!


----------



## VolkerH.

I was wondering how the acoustic qualities of PolyIso are. Would I have to remove the shiny surface ? I like the size they come in and was thinking of being able to slap it to the ceiling and only would need a few as they come on rather large tiles.


----------



## DrPainMD




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10260#post_24717169
> 
> 
> Well if this is the case then PLEASE start a thread showing pictures of what NOT to do. A little bit of humor goes a long way on the interwebs!!



well i got him to ditch the egg carton idea, but hes still gonna paint it black


ill see if i can get pics


----------



## jerrolds

Would bass traps helps when there is no corner? My living room is small/medium sized at 17' x 11 with some of the right side opening up to the hall/dining room. I've placed my sub on the left side where its on the closed side facing a fire place that cuts off a corner

​

This is an apt style condo, so id like to contain as much sound as possible within a certain budget ($100) so im thinking of grabbing some bass traps and 12"x12"x2" acoustic tiles (12 of them) and putting them above my couch to serve as both decoration and treatment


heres an album of my setup ​ - these pics are a bit older and have the sub on the right/open side. Which had less room gain (HK room eq gave my SVS PB-1000 a +4db with the volume at 10oclock on this side, while it gave it a -2db on the left)


thanks


----------



## artur9




> Quote:
> Originally Posted by *jerrolds*  /t/255432/acoustical-treatments-master-thread/10260#post_24717681
> 
> 
> Would bass traps helps when there is no corner?



There's always the ceiling/wall corners if you can work with those.


----------



## wse

Remember What is of very high importance?

The listening room. So important, in fact, that it is hardly distinguishable from the quality of the speaker system itself. It would probably be more accurate to say that the speakers, the room, and the placement of the speakers within the room constitute a single system second in importance only to the program material.


----------



## Archaea

What's the nrc range of standard run of the mill drop ceiling tiles? I'm curious to compare that to ceiling tiles sold under the acoustic premise.


----------



## lbrown105




> Quote:
> Originally Posted by *Archaea*  /t/255432/acoustical-treatments-master-thread/10260#post_24719589
> 
> 
> What's the nrc range of standard run of the mill drop ceiling tiles? I'm curious to compare that to ceiling tiles sold under the acoustic premise.


Archea, I know this is not answering the question you are asking, but did you see my post with link to my results replacing the drop ceiling. I know this is not an option for everyone but some have used a drop ceiling as a bass trap but the DD+GG on clips is for mor than just sound isolation and can also be considered for improved in room response. I incerased my bass SPL response in certain frequencies and also increased the rate of decay at the same time. The physical flexing of the whisper clips and there by mass of the ceiling has some dramatic effects on in room bass response that would require several feet of insulation (40-50hz) to achieve.


If you already saw then I apologize for posting it twice.


http://www.avsforum.com/t/1531346/drop-ceiling-upgrade#post_24708749


----------



## VolkerH.

So I was able to fire up my system for the first time in 'normal' viewing mode and found that the sound is carried all the way from the basement to the kids rooms on the second floor through the heating vents and the returns. They don't originate in my HT room but they pass through. For now I'm working with R19 and will try to cover the ducts. From there everything is still to be decided. I was thinking another layer of R19 but 90degress off, covered by PolyIso panels. Anything to avoid working with DW


----------



## lbrown105




> Quote:
> Originally Posted by *VolkerH.*  /t/255432/acoustical-treatments-master-thread/10260#post_24720848
> 
> 
> So I was able to fire up my system for the first time in 'normal' viewing mode and found that the sound is carried all the way from the basement to the kids rooms on the second floor through the heating vents and the returns. They don't originate in my HT room but they pass through. For now I'm working with R19 and will try to cover the ducts. From there everything is still to be decided. I was thinking another layer of R19 but 90degress off, covered by PolyIso panels. Anything to avoid working with DW


Good advice in the sound proofing thread. This one focuses more on in room response. Cheers


----------



## VolkerH.

Darn ! Sorry !


----------



## lbrown105

No problem just wanted you to get the best advice you can.


----------



## JWagstaff

Quick question about acoustic treatment... I have a room about 15 x 16 x 8, I have a 2x4 absorption panel on the ceiling at the first reflection point, one 2x4 on each side wall at the first reflection point, one 2x4 on the rear wall behind the listening position, and two corner bass traps from floor to ceiling in both back corners of the room. If I was to add one more treatment to the room, what would you suggest?


----------



## fotto




> Quote:
> Originally Posted by *JWagstaff*  /t/255432/acoustical-treatments-master-thread/10260#post_24726233
> 
> 
> Quick question about acoustic treatment... I have a room about 15 x 16 x 8, I have a 2x4 absorption panel on the ceiling at the first reflection point, one 2x4 on each side wall at the first reflection point, one 2x4 on the rear wall behind the listening position, and two corner bass traps from floor to ceiling in both back corners of the room. If I was to add one more treatment to the room, what would you suggest?



"two corner bass traps from floor to ceiling in both *FRONT* corners of the room"


----------



## wse




> Quote:
> Originally Posted by *JWagstaff*  /t/255432/acoustical-treatments-master-thread/10260#post_24726233 Quick question about acoustic treatment... I have a room about 15 x 16 x 8, I have a 2x4 absorption panel on the ceiling at the first reflection point, one 2x4 on each side wall at the first reflection point, one 2x4 on the rear wall behind the listening position, and two corner bass traps from floor to ceiling in both back corners of the room. If I was to add one more treatment to the room, what would you suggest?


I myself likes diffusion at the first point of reflection 

 

try these http://www.vicoustic.com/music-broadcast/products/acoustic-treatment/diffusion/panel/317


----------



## jkkwaz

Hey guys,


I appreciate the advice in advance. I am looking to add some acoustic panels in my theater for first reflections on side walls and ceiling and overall sound absorption. I just ran across this ad on Craigslist and it seems like a good deal. Has anyone ever used this material? Is this appropriate to do what I want? I would probably build frames for this and wrap in fabric with an air gap between this and the wall. Thanks for any quick opinions as I don't want to miss out on the deal if it would work out well for me. Thanks!

http://phoenix.craigslist.org/evl/mat/4472472899.html


----------



## BIGmouthinDC

that is called wood wool and is made by various vendors and formulations. some have concrete in the mix as a fire retardant. Test data is a little hard to find for a specific product but there is data by frequency here and you can compare to other materials:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&ved=0CHQQFjAM&url=http%3A%2F%2Fweb.arch.usyd.edu.au%2F~densil%2FAudio%26Acoustics%2FAbsorption%26InsulationData.xls&ei=eaJ2U7qtNoqBogTeooLQAQ&usg=AFQjCNEhPbtEYJOFYNa8ka-npe6WjeL2yQ&sig2=pKJjbhT3kuhn8r9nJuXtRw


----------



## jkkwaz

Awesome, thanks for the info. I am having a hard time understanding the different sound absorption coefficients. It looks like depending on the thickness (I'm waiting to hear back from him on this) it is between .5 and .85 depending on the frequency. Is this pretty good? How does this compare to 2" Roxul or other materials?


----------



## BIGmouthinDC

knock yourself out. Basically not as much absorbtion. The advantage is it's durability. Once current use is for livestock areas.
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10260#post_24727754
> 
> 
> knock yourself out. Basically not as much absorbtion. The advantage is it's durability. Once current use is for livestock areas.
> http://www.bobgolds.com/AbsorptionCoefficients.htm


I am surprised it is fire rated... It looks like straw in the pictures. Will it have a odor?


----------



## Aarghon

Hello people!


Recently bought dual subs, which are yet to arrive. But that move makes me plan the next upgrade : Room treatments. I've already made some absorption panels made of roxul safe and sound 3 inches deep panels. I've put 3 2x4 panels behind my listening position, and 3 besides my tv ( they are behind my rear ported towers, in fact.)


While my panels did have an effect on sound, I think they only affected it in the mid/high frequencies, and did not much to the lower bass...They helped my sound quality, though.


So, here is what I'm planning to do. I'll go professional, and buy GIK treatments. Or realtraps, don't know yet. I'm tending towards GIK though. But the idea is clear, and I would like feedback on it.

Here is a picture of what I'm planning to do:

 


kitchen is an open plan...


I'd put 2 bass traps straddling corners. as indicated on the room plan. 2 GIK monster bass traps. And I'd put 3x 244 basstraps on the wall behind my listening position with scatter plates to do not over-absorb high frequencies... My room is small, and I think that I might have absorbed high frequencies too much versus lows with my 6 absorptions panels.


Is it a good idea? It's a rough draft , as I'm not really seasoned in audio yet! Would appreciate ideas a lot. Thanks in advance!


----------



## ellisr63

We are trying to figure out how to maintain access for our electrical panel... This is what we have.


Electric panel is behind our new double wall with a removable panel to access... Our problem is I am almost positive the first reflection point will be where the panel access is. How have others dealt with this? We were planning on wrapping some frames with GOM for the complete room, and having acoustic treatments behind them. From what I understand the electrical panel must be easily accessible. How do I make it easily accessible while at the same time taking care of the first reflection? Another issue is how do I mark it so the Fire Dept would know that is where it is without making it be a distraction when watching a movie (the screen ends a little over 1' from the wall)?


----------



## BIGmouthinDC

Does your house have a main electrical shut off outside the house? that is where the fire department is going to want to do their thing. They might just pull the meter.


----------



## ellisr63




> Quote:
> Originally Posted by *BIGmouthinDC*  /t/255432/acoustical-treatments-master-thread/10260#post_24732925
> 
> 
> Does your house have a main electrical shut off outside the house? that is where the fire department is going to want to do their thing. They might just pull the meter.


The outside cutoff is all most directly behind the box, so they can turn the power off from the outside too. I was told though that it still needs to be readily accessible from the inside where the panel is. We have made an access panel that fits nice and snug on the new inner wall and it has 1 layer of OSB so far. We wtill need to get the green glue and one more layer of drywall plus the acoustic treatment. How do you normally conceal the access panel while at the same time make it readily available and identifiable?


----------



## BasementBob




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10260#post_24733134
> 
> 
> make it readily identifiable?



This is repulsive, but a thought

 


Lots of companies will print any digital image, such as a photo, onto acoustic fabric.

So a hinged acoustic panel on the outside covered with printed acoustic fabric (think wall safe behind painting), and a latched sealed door on the 'wall' behind it.

I have no idea what the price would be.



Another way to go would be to leave the panel where it is,

but to reroute the main lines inside the house to a spot where an 'earlier' house shutoff could be easily accessible, and then continue the main line back to where the panel is.

There would still be accessibility issues so the homeowner can get to it, but identifiable for the fire department wouldn't be an issue.


----------



## ellisr63




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10260#post_24733263
> 
> 
> This is repulsive, but a thought
> 
> 
> 
> 
> Lots of companies will print any digital image, such as a photo, onto acoustic fabric.
> 
> So a hinged acoustic panel on the outside covered with printed acoustic fabric (think wall safe behind painting), and a latched sealed door on the 'wall' behind it.
> 
> I have no idea what the price would be.
> 
> 
> 
> Another way to go would be to leave the panel where it is,
> 
> but to reroute the main lines inside the house to a spot where an 'earlier' house shutoff could be easily accessible, and then continue the main line back to where the panel is.
> 
> There would still be accessibility issues so the homeowner can get to it, but identifiable for the fire department wouldn't be an issue.



Thanks, Then the next thing is to figure a color that is not going to be reflecting a lot of light.... Walls will be a dark color to start with... Maybe even black at this point.


----------



## myfipie




> Quote:
> Originally Posted by *JWagstaff*  /t/255432/acoustical-treatments-master-thread/10260#post_24726233
> 
> 
> Quick question about acoustic treatment... I have a room about 15 x 16 x 8, I have a 2x4 absorption panel on the ceiling at the first reflection point, one 2x4 on each side wall at the first reflection point, one 2x4 on the rear wall behind the listening position, and two corner bass traps from floor to ceiling in both back corners of the room. If I was to add one more treatment to the room, what would you suggest?



Basically the more traps you put in corners the better the response will be, so yes cover the front corners if you can. Also get more thick trapping on the back wall.


----------



## myfipie




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/10260#post_24730414
> 
> 
> Hello people!
> 
> 
> Recently bought dual subs, which are yet to arrive. But that move makes me plan the next upgrade : Room treatments. I've already made some absorption panels made of roxul safe and sound 3 inches deep panels. I've put 3 2x4 panels behind my listening position, and 3 besides my tv ( they are behind my rear ported towers, in fact.)
> 
> 
> While my panels did have an effect on sound, I think they only affected it in the mid/high frequencies, and did not much to the lower bass...They helped my sound quality, though.
> 
> 
> So, here is what I'm planning to do. I'll go professional, and buy GIK treatments. Or realtraps, don't know yet. I'm tending towards GIK though. But the idea is clear, and I would like feedback on it.
> 
> Here is a picture of what I'm planning to do:
> 
> 
> 
> 
> kitchen is an open plan...
> 
> 
> I'd put 2 bass traps straddling corners. as indicated on the room plan. 2 GIK monster bass traps. And I'd put 3x 244 basstraps on the wall behind my listening position with scatter plates to do not over-absorb high frequencies... My room is small, and I think that I might have absorbed high frequencies too much versus lows with my 6 absorptions panels.
> 
> 
> Is it a good idea? It's a rough draft , as I'm not really seasoned in audio yet! Would appreciate ideas a lot. Thanks in advance!



Looks like a good plan, but if there is any way to flip the set up to face the sliding door that will work MUCH better. It is going to give you better symmetry/imaging, left and right and also give the speakers a longer throw, which is always a good thing for low end response.








http://www.gikacoustics.com/positioning-listening-spot/


----------



## Aarghon




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10260#post_24735432
> 
> 
> Looks like a good plan, but if there is any way to flip the set up to face the sliding door that will work MUCH better. It is going to give you better symmetry/imaging, left and right and also give the speakers a longer throw, which is always a good thing for low end response.
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.gikacoustics.com/positioning-listening-spot/



Thanks for the answer Mr Kuras! Much appreciated!


I can't place the setup facing the sliding door unfortunately... The kitchen is completely open to the living room! I have to make a compromise on sound versus praticality










I'll try to maximize what I can... Until I can get a dedicated room!


But looks like I have an order too pass soon


----------



## Lindahl

In my small 11x12' room, if my seating is pretty much right against the back wall, is there any reason to use more than 4" of treatment along the back wall? It sounds like that the distance between the boundaries affects the frequency, and since I'm so close, that the thicker treatment might actually not be necessary (the wavelengths of the lower frequencies are too large to really create dips/nulls)? Could I get away with even less? Say 2"? Or does the narrow width of the room mean I need extra thickness?


----------



## HopefulFred




> Quote:
> Originally Posted by *Lindahl*  /t/255432/acoustical-treatments-master-thread/10290#post_24738015
> 
> 
> In my small 11x12' room, if my seating is pretty much right against the back wall, is there any reason to use more than 4" of treatment along the back wall? It sounds like that the distance between the boundaries affects the frequency, and since I'm so close, that the thicker treatment might actually not be necessary (the wavelengths of the lower frequencies are too large to really create dips/nulls)? Could I get away with even less? Say 2"? Or does the narrow width of the room mean I need extra thickness?


There's logic to what you're saying, but in rooms that you can walk in, the transitional frequency range is still below what makes 4" excessive. If you were talking about a small car cabin, you'd probably be right.


That is to say, the Schroeder frequency is related to room size, but it's still low enough, IMO, that you shouldn't skimp on treatment thickness.


----------



## Frank D




> Quote:
> Originally Posted by *Lindahl*  /t/255432/acoustical-treatments-master-thread/10290#post_24738015
> 
> 
> In my small 11x12' room, if my seating is pretty much right against the back wall, is there any reason to use more than 4" of treatment along the back wall? It sounds like that the distance between the boundaries affects the frequency, and since I'm so close, that the thicker treatment might actually not be necessary (the wavelengths of the lower frequencies are too large to really create dips/nulls)? Could I get away with even less? Say 2"? Or does the narrow width of the room mean I need extra thickness?



Go with the 4" or more. Small rooms usually need more treatment in the bass region. 4" or more will do better then 2". 4" will also help with your decay time better then 2".


----------



## myfipie

Agreed with the guys above. I always recommend more then 4" for the back wall when ever possible.


----------



## Nightlord




> Quote:
> Originally Posted by *Lindahl*  /t/255432/acoustical-treatments-master-thread/10290#post_24738015
> 
> 
> In my small 11x12' room, if my seating is pretty much right against the back wall, is there any reason to use more than 4" of treatment along the back wall? It sounds like that the distance between the boundaries affects the frequency, and since I'm so close, that the thicker treatment might actually not be necessary (the wavelengths of the lower frequencies are too large to really create dips/nulls)? Could I get away with even less? Say 2"? Or does the narrow width of the room mean I need extra thickness?



What's on the other side of the back wall? Would it be ok to have it partially sonic transparent?


----------



## Lindahl

The room is actually 11x11, made a typo. The seats (either 2 or 3) are along the wall, in front of the closet. Basically, I have 8" deep broadband absorption on the front wall, 3" of configurable reflective/absorption/diffusion on the side walls and corners of the back wall, and a 5'10 x 6'10 opening on the center back wall for 2' deep broadband absorption (with equipment and AC thrown in there). I also have a 6'x4'10 window that can house additional 8" deep broadband absorption, if that would be useful to do? Since that space is configurable as well (removable panels), I intend on doing measurements and testing for what to do about that area as well. I'm mostly curious about what to do with the fact that I can't treat the corners (~2'x2') of the rear wall with deep absorption. Perhaps this isn't a problem?

 


The wood paneling is shown, as well as the screen wall framing and side wall firring strips. The screen wall is 8" deep, and will be filled with 8" of fluffy pink fiberglass. Firring "strips" of 2x4s are located throughout the room, and velcro is attached to these. Fabric covered 2x2 panels are then attached to the firring strips via the velcro. These panels have no acoustic treatments of their own, and are hollow. This allows any kind of acoustic treatments up to 3" deep to be placed ANYWHERE along the side and back walls. I plan on using a mixture of untreated wall space, 2" OC703 spaced 1" off the wall, and 2" of OC703 covered with binary amplitude diffusors spaced ~1" off the wall ( DIY BAD panels ). Since the amount and variety of these treatments are totally configurable, I'm not committing to any particular placement until the room is completed and everything can be measured and tested.


On a side note, the nice part about the room construction is that, if moving, it can easily be dismantled, with only the screen wall fabric sacrificed (not the screen). There is also only a few small screw holes in the walls that would need to be filled. When family and friends come from out of town, I can quickly remove the fabric and wood panels (due to the velcro), revealing bright colored walls, creating a much more friendly living environment. The fabric panels can be stacked against the screen wall, and the acoustic treatments removed from the wall and placed in the closet.


The system will be 5.2. The listening distance of either 2 or 3 seats is at about 9.5'. The front speakers are behind an AT screen. Spaced about 7' apart (22 degree angle to MLP). The rear speakers will be attached to the ceiling, either along the side walls, or along the rear walls (TBD). Two subwoofers will be located inside the room, and their final location will be determined through measurements and testing, but will likely be located along the side walls, somewhere between the front wall, and halfway into the room. Though, placing them in opposite corners would be an option as well, if that turns out to be the best location. The LCRs will likely be DIY SEOS Fusion 8/10s, the surrounds will likely be DIY Volt 8/10 Coaxials, and the subwoofers will be TC Sounds Axis 15" in a sealed configuration (actually old TC-3000s). Should be pretty easy to hit reference levels for this small of a room. The electronics, projector, and separate in-room AC are housed in the closet, creating a noise-free environment.


----------



## Archaea




> Quote:
> Originally Posted by *Archaea*  /t/255432/acoustical-treatments-master-thread/10260#post_24719589
> 
> 
> What's the nrc range of standard run of the mill drop ceiling tiles? I'm curious to compare that to ceiling tiles sold under the acoustic premise.




Anyone used these ceiling panels from lowes?
http://www.lowes.com/pd_89091-61-1729ABL_0__?productId=3068433&Ntt=armstrong+panel&pl=1&currentURL=%3FNtt%3Darmstrong%2Bpanel%26page%3D1&facetInfo= 



or these on ebay.

http://www.ebay.com/itm/180688671015?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649


----------



## artur9




> Quote:
> Originally Posted by *Archaea*  /t/255432/acoustical-treatments-master-thread/10290#post_24744995
> 
> http://www.ebay.com/itm/180688671015?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649



I bought these. The shopkeeper is a very pleasant person. I'm not sure I achieved what I wanted with them acoustically but they do make the theater nicely dark.


The tiles (I got the 2x2 ones) are the denser fiberglass with one side faced with what seems to be speaker cloth.


----------



## uopdrmark

I'm in the process of trying to convert a room into a theater and I'm in desperate need of acoustic treatment help. I have a pretty bad echo and bass is really muddy and uneven throughout the room at the moment. I will be adding 4 UXL-18 sealed subs to the mix to help with the uneven response but I know I need traps to help clean things up. I've got about 18" behind the screen that I can place insulation so it seems like a great place to put stuff up.


I've been looking into doing a large pink fluffy treatment behind my AT screen and I'm wondering if I should just load the entire wall with pink fluffy and then cover with fabric. I was thinking I would just put up a 2x4 header and then attach 2x4's down to the floor to create a false wall of sorts that I could then place the pink fluffy in between.

Here is the pink fluffy I'd be using:
http://www.homedepot.com/p/Owens-Corning-EcoTouch-9-1-2-in-x-15-in-x-25-ft-R-30-Unfaced-Continuous-Roll-Fiberglas-Insulation-RU70/202585906?N=5yc1vZbay7Z1z0z6bnZ1z0z6ez 


I'm also wondering if the pink fluffy needs to be completely wrapped so it doesn't let fiberglass particles into the air.


Here are a few pics:


----------



## A9X-308

^^ I hope you're planning to bring the tweeters to ear height.


----------



## Archaea

You want thicker pink fluffy for subwoofer frequencies than 4" and thickness matters more than density from what I've been told. Can you use 2x8s and rc-30? (9" thick)


----------



## uopdrmark

Speakers are actually changing to some JTR 212ht's. They will be raised to ear level for sure, everything is just temporary until then.


I am definitely planning on using the 9.5'' thick pink fluffy. I just wasn't totally sure how I'll be securing the pink fluffy. I know I don't want it to sag so I was contemplating trying to hang it somehow so I don't have to worry about that. But 2x8's are an option as well.


----------



## BasementBob




> Quote:
> Originally Posted by *A9X-308*  /t/255432/acoustical-treatments-master-thread/10290#post_24750718
> 
> 
> ^^ I hope you're planning to bring the tweeters to ear height.



Technically, they don't have to be at ear height.


They do have to be aimed, both vertically and horizontally (laser), at the ears.


By way of example, a while ago I was demo-ing a bunch of Pioneer SP-BS22-LR bookshelf speakers that I had on the floor, and the sound was wrong until I canted them upwards by putting books under the fronts so that the tweeters were aimed vertically at the listener's head.


If given a choice between putting speakers below the screen vs above the screen, choose above the screen. Put the tweeters as close to the screen as possible, so with full height speakers, if above the screen, put them upside down with the tweeters on the bottom. Ultimately your goal is to be lost in the movie. People's ears have evolved to detect direction of sounds below them, so they can locate and catch small animals. People's ears are far less good at detecting direction of sounds above. So if you want the sound to appear as if its coming from the screen, and you can't put the speakers behind an acoustically transparent screen (e.g. with a plasma television), then putting the speakers above the screen is optimal.


----------



## BasementBob




> Quote:
> Originally Posted by *uopdrmark*  /t/255432/acoustical-treatments-master-thread/10290#post_24748797
> 
> 
> I will be adding 4 UXL-18 sealed subs to the mix to help with the uneven response but I know I need traps to help clean things up.



The best way to get rid of modal problems is to lessen their effects in the first place by placement.

I presume you know the crawl trick (both variants: sub in tri corner, and sub in listener position ), possibly with RTA/REW.

eljaycanuck espouses has an entertaining technique in post #15 here .


There are several good studies about multi subwoofer placement. A few that come to mind are almost a decade old now: Harmon's multisub.pdf (mostly symmetric placement), Gedlee's symmetric vs asymmetric Sub study (recommended four subs placed: one in a corner, three random, one near ceiling), and David Griesinger's.

In your case, Harmon had one amusing comment: "For practical number of subwoofers, there appears to be no obvious correlation. There is certainly no justification for using more than four."


----------



## uopdrmark




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10290#post_24751629
> 
> 
> The best way to get rid of modal problems is to lessen their effects in the first place by placement.
> 
> I presume you know the crawl trick (both variants: sub in tri corner, and sub in listener position ), possibly with RTA/REW.
> 
> eljaycanuck espouses has an entertaining technique in post #15 here .
> 
> 
> There are several good studies about multi subwoofer placement. A few that come to mind are almost a decade old now: Harmon's multisub.pdf (mostly symmetric placement), Gedlee's symmetric vs asymmetric Sub study (recommended four subs placed: one in a corner, three random, one near ceiling), and David Griesinger's.
> 
> In your case, Harmon had one amusing comment: "For practical number of subwoofers, there appears to be no obvious correlation. There is certainly no justification for using more than four."



Yea, I've read a few of those and I will certainly be trying out some different placement options once the subs are ready. I had originally planned on building 4 massive ported subs for behind the screen placed at 1/4 distances height and width wise but decided against it as there is no way I could fit one of those monsters in the room if the placement wasn't ideal. I'm now going to go with a more conventional sealed enclosure for all 4 and take time to find the best placement.


The screen in a Seymour XD 170'' diagonal 16:9 screen, so there is plenty of room for the speakers behind there. They will be on stands to get to proper ear height as well.


I really am just interested in knowing if creating a wall of bass/broadband trapping is a good idea. I really can't do corner traps as I have 2 doors that swing into the screen wall. I can at best be 18'' from wall behind screen and about 12'' where the doors open.


----------



## uopdrmark

This is the pink fluffy I was planning on using: http://www.homedepot.com/p/Owens-Corning-EcoTouch-9-1-2-in-x-15-in-x-25-ft-R-30-Unfaced-Continuous-Roll-Fiberglas-Insulation-RU70/202585906?N=5yc1vZbay7Z1z0z6bnZ1z0z6ez 


Should I wrap that with landscape cloth? Or something else to keep fiberglass contained?


----------



## sdurani




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10290#post_24751629
> 
> 
> In your case, Harmon had one amusing comment: "For practical number of subwoofers, there appears to be no obvious correlation. There is certainly no justification for using more than four."


Just to put that in context, the Harman paper was addressing seat-to-seat consistency. Using more than 4 subs can give you more output, can give you smoother response, but won't give you a big improvement in seat-to-seat consistency.


----------



## uopdrmark

My room is 20'x21'x10' with the screen on the 20' wall. I just figured out that if I place the bats with 15'' width and 9.5'' deep it will take 7 rolls to cover it completely. If I turn them sideways I could get 15'' deep and it will only take 10 rolls. Seems like a small price to pay for slightly more than 50% increase in depth.


----------



## uopdrmark

I'm imagining something like this with 2 subs up front and 2 in back. I will confirm best placement with REW once setup is complete. UXL-18s wont be for another 4-6 weeks.


----------



## A9X-308




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10300_50#post_24751614
> 
> 
> Technically, they don't have to be at ear height.
> 
> 
> They do have to be aimed, both vertically and horizontally (laser), at the ears.


Whilst that is a better result than simply leaving them as shown in the pic, I can always tell the sound comes from lower than the image which I find distracting and annoying. The best result is actually with them at ear height as the designer intended and using an AT screen is a much, much better idea than above or below. If the screen (assuming projector) has not yet been purchased it should be seriously considered. If you're using an LCD then you have little choice but a flawed layout or possibly a phantom centre if you're seating layout supports it, ie one row, one/two viewers.


----------



## sdurani




> Quote:
> Originally Posted by *uopdrmark*  /t/255432/acoustical-treatments-master-thread/10290#post_24752016
> 
> 
> I'm imagining something like this with 2 subs up front and 2 in back.


In that case, I would centre the front and back subs at the quarter points of room width in order to minimize the first 3 width modes of the room and smoothen out the peak & dips across the seating area.


----------



## BasementBob




> Quote:
> Originally Posted by *uopdrmark*  /t/255432/acoustical-treatments-master-thread/10290#post_24751862
> 
> 
> I really am just interested in knowing if creating a wall of bass/broadband trapping is a good idea.



Nice phrasing, namely the "a good idea".

Will it help modes -- the few axial modes in that direction, yes, between a bit and a good bit.

But is it a good idea, for room ambiance, and other acoustical issues, hmm.


Not including Phillip Newell's non environment rooms (which have extremely deep insulation), low soundproofed rooms, wind-tunnel, and royal (and maybe a couple others),

the largest bass trap I've seen would be at AVS, namely FoLLgoTT's 55cm porous + 10cm air gap absorber wall and he thinks it was a good idea.

But he's also paying attention to room support (not a dead room), and his wall full is on the rear wall not the front wall.


As for the front wall, I did that once. The room had amazing room support before I did it, that totally disappeared after I did.


----------



## uopdrmark




> Quote:
> Originally Posted by *A9X-308*  /t/255432/acoustical-treatments-master-thread/10290#post_24752114
> 
> 
> Whilst that is a better result than simply leaving them as shown in the pic, I can always tell the sound comes from lower than the image which I find distracting and annoying. The best result is actually with them at ear height as the designer intended and using an AT screen is a much, much better idea than above or below. If the screen (assuming projector) has not yet been purchased it should be seriously considered. If you're using an LCD then you have little choice but a flawed layout or possibly a phantom centre if you're seating layout supports it, ie one row, one/two viewers.



I am using a 170" diagonal 16:9 Seymour XD screen and speakers will be level and pointed to main seating position ear level.


> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10290#post_24752353
> 
> 
> Nice phrasing, namely the "a good idea".
> 
> Will it help modes -- the few axial modes in that direction, yes, between a bit and a good bit.
> 
> But is it a good idea, for room ambiance, and other acoustical issues, hmm.
> 
> 
> Not including Phillip Newell's non environment rooms (which have extremely deep insulation), low soundproofed rooms, wind-tunnel, and royal (and maybe a couple others),
> 
> the largest bass trap I've seen would be at AVS, namely FoLLgoTT's 55cm porous + 10cm air gap absorber wall and he thinks it was a good idea.
> 
> But he's also paying attention to room support (not a dead room), and his wall full is on the rear wall not the front wall.
> 
> 
> As for the front wall, I did that once. The room had amazing room support before I did it, that totally disappeared after I did.



I have thought of this potential too and from all I've read it looks like most agreed there cannot be enough bass trapping (in general). I'm sure some disagree, but many think so and at this point that makes sense. On the other hand a lot of people end up overdampening the room by doing too many bass traps without consideration of MF/HF. I could always add 6mil poly to some of the wall if it is in fact too dead, but my thought was make the front wall dead and only doing minimal first reflection points as needed after that. I do want to contain SBIR and a totally dead front wall seems second best to baffle wall which I just don't feel comfortable doing on my own. Not too mention a baffle limits ability to use space as a bass trap.


----------



## ellisr63




> Quote:
> Originally Posted by *uopdrmark*  /t/255432/acoustical-treatments-master-thread/10290#post_24753025
> 
> 
> I am using a 170" diagonal 16:9 Seymour XD screen and speakers will be level and pointed to main seating position ear level.
> 
> I have thought of this potential too and from all I've read it looks like most agreed there cannot be enough bass trapping (in general). I'm sure some disagree, but many think so and at this point that makes sense. On the other hand a lot of people end up overdampening the room by doing too many bass traps without consideration of MF/HF. I could always add 6mil poly to some of the wall if it is in fact too dead, but my thought was make the front wall dead and only doing minimal first reflection points as needed after that. I do want to contain SBIR and a totally dead front wall seems second best to baffle wall which I just don't feel comfortable doing on my own. Not too mention a baffle limits ability to use space as a bass trap.


What projector are you using? I am looking at around that size or 180" too.


----------



## ellisr63

Here is an idea... I have a 4' deep area behind the screen. What if I was to use sound absorbing panels all around the speakers (like a baffle wall) and make them 2' deep (so I can still get at the back of my La Scalas... This would work as a bass trap but at the same time be similar to a baffle wall... Would this work?


----------



## thebland

What is the material of choice to out under Guilford fabric for diffusion properties? And what thickness?


Rhans


----------



## uopdrmark




> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10290#post_24753112
> 
> 
> What projector are you using? I am looking at around that size or 180" too.



I have an Epson 8020 and it's on eco mode and still looks good to me. That said I'm not a videophile so I'm sure someone will chime in and say it can't be done. Bottom line is it looks good to me and all who have seen it.


> Quote:
> Originally Posted by *ellisr63*  /t/255432/acoustical-treatments-master-thread/10290#post_24753124
> 
> 
> Here is an idea... I have a 4' deep area behind the screen. What if I was to use sound absorbing panels all around the speakers (like a baffle wall) and make them 2' deep (so I can still get at the back of my La Scalas... This would work as a bass trap but at the same time be similar to a baffle wall... Would this work?



That is sorta what I'm am thinking but it is definitely not the same as a baffle wall. The baffle wall reinforces the midbass and has no reflections due to flush mount placement. The large 2' bass trap idea should completely absorb anything from bouncing off the front wall which should also solve SBIR. Assuming we are the right track with this, I would guess your speakers would be just fine as they have enormous midbass so no reinforcement should be needed.


Hopefully others will chime in and weigh in on the front wall bass trap idea.


----------



## CheYC

I think I'm going to order a pair of GIK Tri Traps next month, had a question.. One of my walls has chair rail, I'm wondering if it will have any effect since it (along with the baseboard) will be pushing the trap off the wall maybe an inch or so, the traps will not be flush against the corner.


----------



## Aarghon




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10290#post_24764010
> 
> 
> I think I'm going to order a pair of GIK Tri Traps next month, had a question.. One of my walls has chair rail, I'm wondering if it will have any effect since it (along with the baseboard) will be pushing the trap off the wall maybe an inch or so, the traps will not be flush against the corner.



In fact, air gaps are desirable when treating . Even if the gap is built-in in GIK traps, it will do nothing bad adding an inch more, excepted doing a little good!!!


I might be wrong, , but I think what I'm saying is logical


----------



## myfipie




> Quote:
> Originally Posted by *Aarghon*  /t/255432/acoustical-treatments-master-thread/10290#post_24765960
> 
> 
> In fact, air gaps are desirable when treating . Even if the gap is built-in in GIK traps, it will do nothing bad adding an inch more, excepted doing a little good!!!
> 
> 
> I might be wrong, , but I think what I'm saying is logical



Basically you are right. We actually tested the Tri Trap at Riverbank with it tight in the corner then pulled it out a few inches to see the effect. We knew that people would have plugs and things in the way. Basically there was not any kind of negative effect on the testing. In fact it did enhance the low end absorption a bit, but nothing that I believe a human could ever hear.


----------



## CheYC

Thanks, I was fairly sure it was OK, but wanted to doublecheck. I probably won't do floor to ceiling, at least initially, but instead try to cover most corners halfway up the wall first. Is it kosher to place things on top of the traps? To help the WAF? i.e. a small house plant or something?


----------



## uopdrmark

myfipie,


Do you have any comments/suggestions regarding the front wall as a bass/broadband absorber? I'm thinking 9.5" or possibly 15" deep depending on which way I turn the pink fluffy hanging from floor to ceiling across the entire front wall. I don't really have a good space for corner bass traps. I will probably then add some first reflection absorbers with 3" rockwool on sides and rear wall. I guess I could do the ceiling if needed as well. If there is too much MF/HF absorption I could always add some 6mil poly over some areas as needed.


Thanks


----------



## doublewing11

I'm finally getting underway for final project in room.........coffered ceiling with acoustic treatments.


I have several different Quest products in room along with typical EG two layers of Linacoustic RC with 3mil poly sandwiched between layers for front facade wall.


I have room for 6 inches in coffered ceiling for treatment and trying to decide between OC 703/705 in either 2 or 4 inches. My understanding, 4" is better for broadband absorption compared to two inches but am worried too much absorption exists already since every square inch of room is covered in some form of treatment ie perf-sorber, Q-Sorber, and other various Quest products.


I will be using MSR 3D diffusers in rear but from what I've read, 6 inch diffuser would work better for lower in spectrum than two inches. I'm open to using other diffusers if price performance alternatives are available or better suited for my situation.


Just trying to find out if my thoughts are on right track and am willing to contact professional if there are issues with my plan. Here is a diagram of my plan for absorption and diffusion..........

 


Absorption is for first reflections on ceiling for 1st and 2nd row seating........all absorption covers mid-points for LCR speakers. Scale is one square is one square foot.......seating is at 12.5 ft and 18.5 feet.


----------



## Nyal Mellor




> Quote:
> Originally Posted by *doublewing11*  /t/255432/acoustical-treatments-master-thread/10320#post_24782083
> 
> 
> I'm finally getting underway for final project in room.........coffered ceiling with acoustic treatments.
> 
> 
> I have several different Quest products in room along with typical EG two layers of Linacoustic RC with 3mil poly sandwiched between layers for front facade wall.
> 
> 
> I have room for 6 inches in coffered ceiling for treatment and trying to decide between OC 703/705 in either 2 or 4 inches. My understanding, 4" is better for broadband absorption compared to two inches but am worried too much absorption exists already since every square inch of room is covered in some form of treatment ie perf-sorber, Q-Sorber, and other various Quest products.
> 
> 
> I will be using MSR 3D diffusers in rear but from what I've read, 6 inch diffuser would work better for lower in spectrum than two inches. I'm open to using other diffusers if price performance alternatives are available or better suited for my situation.
> 
> 
> Just trying to find out if my thoughts are on right track and am willing to contact professional if there are issues with my plan. Here is a diagram of my plan for absorption and diffusion..........
> 
> 
> 
> 
> Absorption is for first reflections on ceiling for 1st and 2nd row seating........all absorption covers mid-points for LCR speakers. Scale is one square is one square foot.......seating is at 12.5 ft and 18.5 feet.



Can't answer that question until you tell us:

a) what speakers you are using (vertical off axis, how similar is it to the on axis)

b) how high your ceiling is (reflected path length relative to direct sound and so estimation of SPL loss through reflected path)

c) what the late reflected field (reverberation) looks like in your room. Measurements are best (T60) but simulation ok


----------



## doublewing11




> Quote:
> Originally Posted by *Nyal Mellor*  /t/255432/acoustical-treatments-master-thread/10320#post_24783088
> 
> 
> Can't answer that question until you tell us:
> 
> a) what speakers you are using (vertical off axis, how similar is it to the on axis)
> 
> b) how high your ceiling is (reflected path length relative to direct sound and so estimation of SPL loss through reflected path)
> 
> c) what the late reflected field (reverberation) looks like in your room. Measurements are best (T60) but simulation ok



Triad Gold LCR

Triad Silver LCR for surrounds......6 total


Ceilings are 10 ft


I can measure and post........


----------



## myfipie




> Quote:
> Originally Posted by *doublewing11*  /t/255432/acoustical-treatments-master-thread/10320#post_24783249
> 
> 
> 
> I can measure and post........



If you measure be sure to measure each speaker then both. Do not move the mic between measurements. You can then view the ETC for the reflections. Generally speaking you want to use 4" of absorption if possible for the early reflection points.


----------



## doublewing11




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10320#post_24787705
> 
> 
> If you measure be sure to measure each speaker then both. Do not move the mic between measurements. You can then view the ETC for the reflections. Generally speaking you want to use 4" of absorption if possible for the early reflection points.



Thanks,


I'm reading conflicting info on broadband absorption on 4" OC 703 and 705. What's the skinny on either product......


BTW, your Gridfusor diffuser looks promising but 6" depth is 1" too deep........


----------



## doublewing11




> Quote:
> Originally Posted by *myfipie*  /t/255432/acoustical-treatments-master-thread/10320#post_24787705
> 
> 
> If you measure be sure to measure each speaker then both. Do not move the mic between measurements. You can then view the ETC for the reflections. Generally speaking you want to use 4" of absorption if possible for the early reflection points.



BTW,


What are the differences acoustically between these products.....


MSR 2D or 6D




  


Acoustic Frontier's ceiling diffuser option

 


GIK Acoustic's Gridfuser Diffuser

 


Would like to know before I settle on a path.....


----------



## BasementBob




> Quote:
> Originally Posted by *doublewing11*  /t/255432/acoustical-treatments-master-thread/10320#post_24802865
> 
> 
> What are the differences acoustically between these products.....



The best way to know would be if they've published several-frequency spatial response diffusion graphs for them. Without that, you can't really compare them. Like the bottom right of this simulator:










from http://www.gearslutz.com/board/studio-building-acoustics/766977-diy-sound-diffusers-free-blueprints-slim-optimized-diy-diffuser-designs-fractals-6.html 










from http://www.gearslutz.com/board/studio-building-acoustics/654179-poly-coefficients-cont-another-thread.html 










from http://www.hxaudiolab.com/sound-splash.html 


That said, there are some guesses you can make.


Some diffusers are simple mirror reflectors. Some take advantage of variations on QRD (quadratic-residue diffusor) shapes, based on Schroeders' number-theoretic diffusors to remove/reduce coloration and echoes, in 2D , or 3D such as RPG's Skyline 


The first rule is: "Wavelengths significantly larger than an object are ignored by the object. Wavelengths significantly smaller than an object are reflected specularly (like light on a mirror). Wavelengths the same size as an object are reflected randomly." This image shows this rule:




















So my bet is you've already got them in order, from least diffusive to most diffusive. The last requiring that it be arranged in a cube like that, not broken up and then placed onto a wall in which case the "Acoustic Frontier's ceiling diffuser option" would trump out of the four you've shown.


You should also ask yourself where you want the sound energy to go. Do you just want to reduce the first reflected energy, or you want to reflect it around the room against other reflective surfaces to build up a feeling of spaciousness. To answer those questions, it depends on what else you have in the room and where. 2D diffusers can be directional more easily than 3D diffusers. None of your four images are high frequency 2D diffusers (they're all 3D), but they're all mid frequency reflectors especially the first two.


----------



## doublewing11




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10320#post_24803818
> 
> 
> The best way to know would be if they've published several-frequency spatial response diffusion graphs for them. Without that, you can't really compare them. Like the bottom right of this simulator:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> from http://www.gearslutz.com/board/studio-building-acoustics/766977-diy-sound-diffusers-free-blueprints-slim-optimized-diy-diffuser-designs-fractals-6.html
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> from http://www.gearslutz.com/board/studio-building-acoustics/654179-poly-coefficients-cont-another-thread.html
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> from http://www.hxaudiolab.com/sound-splash.html
> 
> 
> That said, there are some guesses you can make.
> 
> 
> Some diffusers are simple mirror reflectors. Some take advantage of variations on QRD (quadratic-residue diffusor) shapes, based on Schroeders' number-theoretic diffusors to remove/reduce coloration and echoes, in 2D , or 3D such as RPG's Skyline
> 
> 
> The first rule is: "Wavelengths significantly larger than an object are ignored by the object. Wavelengths significantly smaller than an object are reflected specularly (like light on a mirror). Wavelengths the same size as an object are reflected randomly." This image shows this rule:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> So my bet is you've already got them in order, from least diffusive to most diffusive. The last requiring that it be arranged in a cube like that, not broken up and then placed onto a wall in which case the "Acoustic Frontier's ceiling diffuser option" would trump out of the four you've shown.
> 
> 
> You should also ask yourself where you want the sound energy to go. Do you just want to reduce the first reflected energy, or you want to reflect it around the room against other reflective surfaces to build up a feeling of spaciousness. To answer those questions, it depends on what else you have in the room and where. 2D diffusers can be directional more easily than 3D diffusers. None of your four images are high frequency 2D diffusers (they're all 3D), but they're all mid frequency reflectors especially the first two.




Thanks for informative post......it was a slow read due to understanding graphs, their meaning etc.....


My room sounds good all ready due to upper 1/3 wall around room contains Quest Q-Perf treatments, lower 2/3's with either Q-Sorber or Q-Excel panels........


What I do have is a reverberation issue which can be attributed to untreated ceiling. I treated my screen wall ceiling which helped with issue to some degree...........of course all changes have been measured before and after with REW.


My conclusion after experiments was treating ceiling at 1st reflection points completely tamed the frquency issue I was hearing and detecting. In the back of ceiling area, I don't have similar products I used on ceiling front to test and measure results. It's a crap shoot finding correct 3D diffiser since I can't test in room myself.


I've searched for products and the MSR product seems to meet my needs best ie. diffuser treatment for back ceiling area to increase spaciousness/ surround effect.


To be honest, after paying big bucks for Quest treatments, I was disappointed in what they actually were. Yes, I understand R&D time.......but still. I don't want to do the same for 5-6 2X2ft ceiling diffusers. I'm using five 2X4 OC 703 4" treatments for front of ceiling which is a HUGE saving over similar Quest treatments, but am still undecided on what six 2x2ft 3D panels I need. If someone con convince me otherwise, I'm all ears............


----------



## CheYC

I haven't really been able to find a comparison between the ATS corner bass traps and the GIK Tri Traps, there's data on each on their respective websites but to be honest, I'm not sure how to interpret it... They're essentially identical in size/price, just wondering if there's any inherent differences.


----------



## BasementBob




> Quote:
> Originally Posted by *doublewing11*  /t/255432/acoustical-treatments-master-thread/10320#post_24805784
> 
> 
> after paying big bucks for Quest treatments,


Manufactured tend to have some fireproofing and a reasonable balance between rigidity of material and weight.


But there's always DIY.


Polycylindricals are easy to make (e.g. four columns for your surrounds), and do debatably better than QRDs.

Most reverberation chambers and large music halls, which are required to have diffuse sound for their tests, use polys instead of QRDs.

e.g.









from http://www.acoustics.salford.ac.uk/facilities/?content=reverb 

Just make absolutely sure you don't make them all the same size/diameter, because you'll get lobbing which you don't want.




















Here's a ceiling polysorber
http://www.bobgolds.com/TrapTodd/home.htm 


By combining room shape, with common materials such as a bunch of wooden blocks, or even stone, you can also get diffusion











This fella made his own out of Styrofoam
http://www.bobgolds.com/DifuserKgveteran/home.htm 


The RPG Skylines have been copied to one degree or another all over the place.

Technically the RPG ones are probably the best numerically -- to protect the numbers their patent application deliberately has a couple of wrong well depths. Nonetheless you could look up their patent application and use those numbers and not go wrong.










These numbers, for example, aren't as good, but they're probably almost as good.
http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/720982-diffusion-confusion.html 
https://www.youtube.com/watch?v=2e3jtqgTmEI 
https://www.youtube.com/watch?v=oHTmNyo_0O0 



Blackbird Studio C took this to the extreme. Their ceiling diffuser pattern and depth is incredible. Its a very unusual space to work in acoustically.
http://recording.de/uploads/newbb/50c8b5d59ca085cad2a02465fe27189a.jpg 
http://download.sea-vertrieb.de/newsletterarchiv/2009/docs/blackbird_studio.jpg 
http://1.bp.blogspot.com/-ocp29ygwcRs/UceRenIddfI/AAAAAAAABhw/po28GjEGfPI/s1600/IMG_3306.JPG 
https://www.youtube.com/watch?v=peCF0gwTWoE 


[humor]I'm guessing since you're leaning towards MSR, you're not going to mini Blackbird[/humor]
https://www.youtube.com/watch?v=PtpJtv5ngew 


Some other graphs:




















Essentially, diffusion is just bouncing the sound in multiple directions, to

a) reduce the dB of the first reflection, and

b) increase the complexity of the sound field, giving a feeling of spaciousness.


Sometimes, just letting a woman with a credit card loose in a room does wonders for diffusion, and high frequency absorption.


But she wouldn't do this
https://www.youtube.com/watch?v=FOjHsexNBTQ#t=501


----------



## BasementBob




> Quote:
> Originally Posted by *doublewing11*  /t/255432/acoustical-treatments-master-thread/10320#post_24805784
> 
> 
> Quest Q-Perf treatments ...
> 
> To be honest, after paying big bucks for Quest treatments, I was disappointed in what they actually were. Yes, I understand R&D time.......


I was curious what these were. They remind me a lot of old RPG BAD Panels .


----------



## BasementBob

For ideas, even DIY ideas,

A bunch of images of Diffusion walls and ceilings, various products from RPG.

(Despite the filenames, only a couple are BAD panels.)
http://www.bobgolds.com/Diffusion/RpgBad01.png 
http://www.bobgolds.com/Diffusion/RpgBad02.png 
http://www.bobgolds.com/Diffusion/RpgBad03.png 
http://www.bobgolds.com/Diffusion/RpgBad04.png 
http://www.bobgolds.com/Diffusion/RpgBad05.png 
http://www.bobgolds.com/Diffusion/RpgBad06.png 
http://www.bobgolds.com/Diffusion/RpgBad07.png 
http://www.bobgolds.com/Diffusion/RpgBad08.png 
http://www.bobgolds.com/Diffusion/RpgBad09.png 
http://www.bobgolds.com/Diffusion/RpgBad10.png 
http://www.bobgolds.com/Diffusion/RpgBad11.png 
http://www.bobgolds.com/Diffusion/RpgBad12.png 
http://www.bobgolds.com/Diffusion/RpgBad13.png 
http://www.bobgolds.com/Diffusion/RpgBad14.png 
http://www.bobgolds.com/Diffusion/RpgBad15.png 
http://www.bobgolds.com/Diffusion/RpgBad16.png 
http://www.bobgolds.com/Diffusion/RpgBad17.png 
http://www.bobgolds.com/Diffusion/RpgBad18.png 
http://www.bobgolds.com/Diffusion/RpgBad19.png 
http://www.bobgolds.com/Diffusion/RpgBad20.png 
http://www.bobgolds.com/Diffusion/RpgBad21.png 
http://www.bobgolds.com/Diffusion/RpgBad22.png 
http://www.bobgolds.com/Diffusion/RpgBad23.png 
http://www.bobgolds.com/Diffusion/RpgBad24.png 
http://www.bobgolds.com/Diffusion/RpgBad25.png 
http://www.bobgolds.com/Diffusion/RpgBad26.png


----------



## doublewing11




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10320#post_24806339
> 
> 
> I was curious what these were. They remind me a lot of old RPG BAD Panels .



You are absolutely correct.......they are almost exactly like RPG Bad Panels...........and price similar!










I think I had 4-5 in my acoustical plan.........ie 4 X 8 ft sheets! Big bucks on those four sheets....


Here are other diffusers I found....manufacturer Auralex.......don't know quality or effectiveness.


----------



## doublewing11




> Quote:
> Originally Posted by *BasementBob*  /t/255432/acoustical-treatments-master-thread/10320#post_24806373
> 
> 
> For ideas, even DIY ideas,
> 
> A bunch of images of Diffusion walls and ceilings, various products from RPG.
> 
> (Despite the filenames, only a couple are BAD panels.)
> http://www.bobgolds.com/Diffusion/RpgBad01.png
> http://www.bobgolds.com/Diffusion/RpgBad02.png
> http://www.bobgolds.com/Diffusion/RpgBad03.png
> http://www.bobgolds.com/Diffusion/RpgBad04.png
> http://www.bobgolds.com/Diffusion/RpgBad05.png
> http://www.bobgolds.com/Diffusion/RpgBad06.png
> http://www.bobgolds.com/Diffusion/RpgBad07.png
> http://www.bobgolds.com/Diffusion/RpgBad08.png
> http://www.bobgolds.com/Diffusion/RpgBad09.png
> http://www.bobgolds.com/Diffusion/RpgBad10.png
> http://www.bobgolds.com/Diffusion/RpgBad11.png
> http://www.bobgolds.com/Diffusion/RpgBad12.png
> http://www.bobgolds.com/Diffusion/RpgBad13.png
> http://www.bobgolds.com/Diffusion/RpgBad14.png
> http://www.bobgolds.com/Diffusion/RpgBad15.png
> http://www.bobgolds.com/Diffusion/RpgBad16.png
> http://www.bobgolds.com/Diffusion/RpgBad17.png
> http://www.bobgolds.com/Diffusion/RpgBad18.png
> http://www.bobgolds.com/Diffusion/RpgBad19.png
> http://www.bobgolds.com/Diffusion/RpgBad20.png
> http://www.bobgolds.com/Diffusion/RpgBad21.png
> http://www.bobgolds.com/Diffusion/RpgBad22.png
> http://www.bobgolds.com/Diffusion/RpgBad23.png
> http://www.bobgolds.com/Diffusion/RpgBad24.png
> http://www.bobgolds.com/Diffusion/RpgBad25.png
> http://www.bobgolds.com/Diffusion/RpgBad26.png



Thanks!!!


You've given me a lot of home work! I'll go through each and every one!


----------



## BasementBob

BTW, I don't know if anyone actually built this sort of thing as a poly,

or used wedges to create a reflection free zone of sorts although I suspect some of the concepts are off here for a variety of reasons,

but wedge absorbers with reflective sides have been done (e.g. last one).


[BTW, this is probably obvious, but if you RightMouseButton over each of these one at a time, and select "open in a new Tab" for each, opening a tab for each so they're all available simultaneously in tabs, you can then click on each tab to quickly go back and forth between them all]

http://www.bobgolds.com/WallWedgeAbsorber/HTPolyIdea.GIF 
http://www.bobgolds.com/WallWedgeAbsorber/HTPolyIdea2.GIF 
http://www.bobgolds.com/WallWedgeAbsorber/OldIdea.GIF 
http://www.bobgolds.com/WallWedgeAbsorber/PointyWedgeIdea.GIF 
http://www.bobgolds.com/WallWedgeAbsorber/PolyIdea.GIF 
http://www.bobgolds.com/WallWedgeAbsorber/Master_Suite_lg.jpg


----------



## BasementBob




> Quote:
> Originally Posted by *doublewing11*  /t/255432/acoustical-treatments-master-thread/10320#post_24806690
> 
> 
> Here are other diffusers I found....manufacturer Auralex.......don't know quality or effectiveness.


Auralex designs and acousticians are tops.

And priced the same.


----------



## myfipie




> Quote:
> Originally Posted by *CheYC*  /t/255432/acoustical-treatments-master-thread/10320#post_24805884
> 
> 
> I haven't really been able to find a comparison between the ATS corner bass traps and the GIK Tri Traps, there's data on each on their respective websites but to be honest, I'm not sure how to interpret it... They're essentially identical in size/price, just wondering if there's any inherent differences.



If you would like give me a call or email through my company website. I can give you the run down of your product.


----------



## baloo_btru

Forgive me for the noob questions but I think it's better to post here instead of making a new thread for now.


I am trying to get the double use of blacking out a short side wall to minimize light and sound reflections. The wall is approximately 6'x9' and I want to cover the whole thing in something as thin as possible (definitely not 2"+; max 1" but thinner would be great) that will provide better sound response than drywall and won't reflect as much as even matte paint.


I was thinking some very thick, heavy acoustical fabric or some thin sound panels like these: http://4seating.com/home-theater-decor/acoustical-wall-panels-standard.htm 


What else is out there? I want to minimize the cost and the light reflection is primary while sound reflection is secondary.


I am going with black. If it makes a difference, I will also be covering a section of wall over my fireplace which is about 4.5'x5' and it sticks out from the wall so I'd like to wrap it around. But I may just put some panels up there. 2 of of other main parts of the room are covered in books so no treatments will be going there and I think the books in general do an ok job.


Thoughts?


----------



## xzener

Hello,

I have a small room, about 10x16 with a 9' ceiling. I plan on building soffit around the perimeter of the ceiling. If I were to fill it with insulation and cover the bottom with GOM... Would that be ample for a bass trap, or will the screen wall still require traps in the corners??


----------



## thebland

Who makes a good, quality diffusor material that can be covered with fabric that comes in sheets so I can cut the sizes I need? 

Any links to pix, website?


----------



## HopefulFred

Nobody. That product doesn't exist, and can't exist, IMO. 

Most diffusers are not sheets. Amplitude (edit: I meant to say phase) gratings can be designed very thin, and can work as diffusers - but are technically different. The number theory that underpins these products requires that for optimal performance a complete series be used, so no company is going to provide you with a complete series and invite you to cut it in pieces. Further, complete installations should consider the way one iteration of a diffuser or phase grating interacts with the next - so again, cutting to fit will be discouraged. 

Hope that helps.


----------



## doublewing11

thebland said:


> Who makes a good, quality diffusor material that can be covered with fabric that comes in sheets so I can cut the sizes I need?
> 
> Any links to pix, website?





HopefulFred said:


> Nobody. That product doesn't exist, and can't exist, IMO.
> 
> Most diffusers are not sheets. Amplitude gratings can be designed very thin, and can work as diffusers - but are technically different. The number theory that underpins these products requires that for optimal performance a complete series be used, so no company is going to provide you with a complete series and invite you to cut it in pieces. Further, complete installations should consider the way one iteration of a diffuser or phase grating interacts with the next - so again, cutting to fit will be discouraged.
> 
> Hope that helps.


Fred hit the nail on the head.........

I've been calling manufacturers along with middle-men distributors for my projects dimensions. I've found a product that comes in a fabric panel which is 2' X 4'........I don't need product in fabric so distributor is checking if I can just receive diffuser with out frame and fabric. Product is quite spendy but will be half without other goodies.

If this product doesn't work out........then torn between Auralex T-diffuser and MSR 2" 3D products. If money is issue, MSR product is a little more than a grand while Auralex product is 1/4 cost. I'm only concerned with performance which I haven't seen raw data on either.


----------



## thebland

I'm not the theater phase to redo all my acoustical work but am re-doing my back wall to close off the equipment and projector (my noise floor will be crazy, crazy low). I'm putting in a couple doors that blend with the real wall as accessto racks and can cover the door with some sort of foam, etc that can be 2". So, I need something relatively effective. Rock wool, etc or something I can buy and cut?

Thanks!


----------



## myfipie

xzener said:


> Hello,
> 
> I have a small room, about 10x16 with a 9' ceiling. I plan on building soffit around the perimeter of the ceiling. If I were to fill it with insulation and cover the bottom with GOM... Would that be ample for a bass trap, or will the screen wall still require traps in the corners??


The more corner area you cover the better the response, but the idea you will work great! What are the sizes of the soffit you have? Generally for a soffit design I like to use 16"x16". Similar to the following.
http://www.gikacoustics.com/product/gik-acoustics-soffit-bass-trap/


----------



## xzener

Thanks Glenn,

But I was referring to a soffit above the perimeter of the room. It will be 12" X 16" filled with insulation batting. The corners behind the screen wall was what I was hoping to get away from. You are saying the more in the corners the better right? So the above sofit bass trap should help??


----------



## ellisr63

What is the recommended way of making acoustic panels for the ceiling? How do you stop the fabric from sagging? I was thinking of using 1/4" thick foam board and attaching black material to it for the whole ceiling and then installing eye hooks (before the first layers of panels are completed so it grabs at the hat channels) into the ceiling to hang acoustic panels but I don't want any sagging material.

Suggestions as to what works would be appreciated.


----------



## xzener

Just received 2 cases of OC703, 24X48X2. I plan on covering the wall behind the screen wall. How are you guys applying these?? Are they prewrapped in GOM?? Are they spray painted black?? I will be using Rotofast fasteners to attach them to the wall. Please help me get started.

I'm reading 1" thick OC703 is what others are using... Is 2" too thick??

Never mind... Just read most people use 1" Linacoustic. I will buy a roll of that stuff for the screen wall. I will use the 2" OC703 for corner bass traps.


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## myfipie

> It will be 12" X 16" filled with insulation batting.


Would be nice if they where a bit bigger, but it still should work well. Be sure to post some pictures once you are done.


----------



## byancey

Looking for some help on the best approach for corner bass traps using Johns Manville MinWool Sound Attenuation Fire Batts. Found this for a great price at my local Lowes. It comes in packs of 10 16"x48"x3" Batts. It appears to be comparable to OC703 at similiar thickness (slightly less effective at the very low end), but for the price I paid, I can double stack these and it would still be far more cost effective than a sheet of OC703. These are batts rather than rigid boards, but they do appear to be very solid and easy to work with (more stable and less smelly than Roxul SafeNSound). Here's the sound coefficients from JMs spec sheet for the batts.










I have a false screen wall two feet from my actual wall which I recently added to my Theater specifically for the purpose of hiding sound treatments. Still thinking about how much treatment to put in there along the back wall, but I do know I want corner bass traps. It seems that super chuck traps are more common with softer materials as opposed to corner spans with more rigid materials such as OC703. However, at only 16" wide, I'll end up with super chunks that are 16" on the sides and about 22" on the diagonal (stacked floor to ceiling). Is this a large enough trap to be effective given my material? 

The other approach I've considered is cutting the sheets in half and doubling them up to create a 16"x24"x6" block and then tapering the 16" edge and stacking these diagonal across the corner on the 24" edge..effectively spanning the full corner 6" deep with an air gap behind. 

The superchunk approach would use about 11 batts to completely fill a corner. The fill would be solid, but less surface area on the diagonal. 

The spanning approach would only use 6 batts to fill the same corner. This yields more surface area on the diagonal, but with an air gap behind rather than solid fill.

Given that I have the space to work with, doubling up the batts and spanning the corner seems like the obvious approach to me. Would love to hear input from others in this forum? Is my logic sound here, or will I get more benefit from the smaller superchunk approach?


----------



## sigma722

Do any of you have any extraordinary posts/threads saved that help explain acoustic treatments with the what why where how?

This thread seems like an awesome discussion, but I was kinda hoping to have a nice OP similar to the sound isolation thread to help point me in the right directions.

Thanks!


----------



## ellisr63

Our front stage is just a short bit that extends to behind our AT screen... I was thinking og using a hole saw to make some holes in the curved front and then stuff the whole stage with insulation... Will that work as a bass trap? Here is a picture of our front stage...

Under the center channel is a Danley DTS-10 which comes up to the front of the stage,,, We will be sealing the mouth of the sub to the stage. The left and right speakers will be installed at the same level as the center by making a 2x4 framework... Under the left and right there will also be fiberglass insulation. I am also debating on using some rubber matt I have to hang from the ceiling behind the speakers and then fill the cavity behind the rubber with insulation (floor to ceiling)... Does this sound like a good idea? Any suggestions?

tia,
Ron


----------



## myfipie

sigma722 said:


> Do any of you have any extraordinary posts/threads saved that help explain acoustic treatments with the what why where how?
> 
> This thread seems like an awesome discussion, but I was kinda hoping to have a nice OP similar to the sound isolation thread to help point me in the right directions.
> 
> Thanks![/QUOT
> 
> See some of the following videos and articles to see if this gives you a hand.
> 
> http://www.gikacoustics.com/educational-videos/
> http://www.gikacoustics.com/articles/


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## BamaDave

Does anyone know the basis for positioning the overhead ceiling*diffusors? In *Anthony Grimani home theater design heuses the overheads just behind the listener and I trying to get a betterunderstanding on how to determine the best spot to add them. Any expert opinions?
Here is a link toan example of what I'm talking about. Funny enough, my wife actually likes the look!
http://www.soundandvision.com/content/acoustics-101


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## PrimeTime

baloo_btru said:


> I am trying to get the double use of blacking out a short side wall to minimize light and sound reflections. The wall is approximately 6'x9' and I want to cover the whole thing in something as thin as possible (definitely not 2"+; max 1" but thinner would be great) that will provide better sound response than drywall and won't reflect as much as even matte paint.


Consider black olefin indoor/outdoor carpet. Definitely less reflective than paint (quite useful behind Acoustically Transparent projection screens). Widely available at carpet warehouses; Depot has it too (possibly as a Special Order).


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## baloo_btru

PrimeTime said:


> Consider black olefin indoor/outdoor carpet. Definitely less reflective than paint (quite useful behind Acoustically Transparent projection screens). Widely available at carpet warehouses; Depot has it too (possibly as a Special Order).


Thanks. Does that do much with the sound?


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## PrimeTime

Carpet on the walls absorbs almost everything above 4 kHz, a lot above 1 kHz, some above 250 Hz and not much below that. Some might consider that a little too "dead," but a little EQ and tweaking of the modern surround processing (assuming you have "side" surround radiators) can dial in whatever "live" acoustical property your heart desires, free of the reflections and effects of the (previiously) live wall.

The thing about carpet on drywall, you might not want to just "go for it" and glue it to the drywall as that is sorta permanent (as in, replace drywall when dissatisfied). One way around that is to cut the wall carpet to size and glue it to an intermediate membrane (such as rigid foam or, in my case, plastic trellis). Once this assembly is dry, mark the carpet where the wall studs will be (with masking tape) and attach it to the wall with an 18-gauge finish nailer, The nap of the carpet will hide the fasteners, and you can take it down quickly if you change your mind (or move), and will only have a little spackling and repainting for the drywall to be good as new.


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## Maklar

A quick question, I see a lot of information on diy absorbers but can anyone point to some diy diffusers and slat scatterers?


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## myfipie

Maklar said:


> A quick question, I see a lot of information on diy absorbers but can anyone point to some diy diffusers and slat scatterers?


Does not show you how to make them but does do the calculations for you.
http://www.mh-audio.nl/ACalculators.asp#showcalc


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## BamaDave

????????????????




BamaDave said:


> Does anyone know the basis for positioning the overhead ceiling*diffusors? In *Anthony Grimani home theater design heuses the overheads just behind the listener and I trying to get a betterunderstanding on how to determine the best spot to add them. Any expert opinions?
> Here is a link toan example of what I'm talking about. Funny enough, my wife actually likes the look!
> http://www.soundandvision.com/content/acoustics-101


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## Nightlord

You may want to diffuse, or partially diffuse the first reflection location(s). You may also want to dampen the area above and partially towards the first reflection.

Myself, I'll just use interleaved wood (3"x2" with 2" spacing) panels going lengthwise in the room for diffusion, that's what my acoustician ordered for my room, but I have dampened above the speakers on my own accord... His comment was "at worst it won't worsen anything"


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## Maklar

myfipie said:


> Does not show you how to make them but does do the calculations for you.
> http://www.mh-audio.nl/ACalculators.asp#showcalc


Thanks, I also found a thread in the diy speakers, I limited my initial search to just the dedicated theater area.

http://www.avsforum.com/forum/155-diy-speakers-subs/1312919-diy-sound-diffusers.html


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## ellisr63

ellisr63 said:


> Our front stage is just a short bit that extends to behind our AT screen... I was thinking og using a hole saw to make some holes in the curved front and then stuff the whole stage with insulation... Will that work as a bass trap? Here is a picture of our front stage...
> 
> Under the center channel is a Danley DTS-10 which comes up to the front of the stage,,, We will be sealing the mouth of the sub to the stage. The left and right speakers will be installed at the same level as the center by making a 2x4 framework... Under the left and right there will also be fiberglass insulation. I am also debating on using some rubber matt I have to hang from the ceiling behind the speakers and then fill the cavity behind the rubber with insulation (floor to ceiling)... Does this sound like a good idea? Any suggestions?
> 
> tia,
> Ron



Is this a good idea... Or should I leave it empty under the stage and open in the rear, and just cover the rear walls with insulation?


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## Nightlord

You can never have too much bass trapping, don't waste the opportunity!


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## ellisr63

Nightlord said:


> You can never have too much bass trapping, don't waste the opportunity!


Would a 3" hole saw be big enough for cutting the holes in the front of the stage? Do I need to use acoustic fabric on the front or can it be carpet?


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## PrimeTime

Carpet is pretty transparent at low frequencies. More rugged and, over time, more uniform than fabric.


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## ellisr63

When making the wall acoustic materials... Do I need to leave a gap to the wall or do they go flush to the wall?


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## Nightlord

ellisr63 said:


> When making the wall acoustic materials... Do I need to leave a gap to the wall or do they go flush to the wall?


Depends om if the materials are acoustically (semi-)transparent or not. If they are, then leaving a gap is often a bonus. If they aren't- then up against the wall with them to preserve room size.


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## myfipie

ellisr63 said:


> When making the wall acoustic materials... Do I need to leave a gap to the wall or do they go flush to the wall?


I highly recommend a gap if you can afford giving up the extra space. Even a 1" to 2" or so will help.


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## BB1111

Wonder if I can get some help for my room treatments. Would like a once-and-for-all setup answer since I've been experimenting with treatments for what seems like ages now.

I have trouble getting a solid answer because all my speakers are electrostatics and nobody seems to have that much experience treating them and handling the back-wave.

I've attached a few pictures of the room and measurements from REW, ignore the A,B,C, etc red boxes in the room picture, the brown boxes are where the speakers are and I've also added wide channels at 60 degrees from the MLP.

What would you guys recommend? I can post more graphs later tonight, subs are placed at the B and C positions.

Thank you

http://imgur.com/a/l8Dmu

Dual Subs with Audyssey on:

http://i.imgur.com/KPflKGA.png


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## PrimeTime

Electrostatics, or dipole radiators of any kind (Magneplanars, etc) are a whole different ballgame.

Some people prefer dipoles because of the ethereal presence that the backwave creates. (Some people like the old Bose 901 schtick too). Other people perceive this added presence as "muddying" the sound. It is a matter of taste, and does indeed complicate the problem of how to "treat" the acoustical space.

The nice thing about dipoles is that their radiation pattern usually nulls out some of the off-axis sound that would otherwise tend to produce the dreaded "early reflections."


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## myfipie

BB1111 said:


> Wonder if I can get some help for my room treatments. Would like a once-and-for-all setup answer since I've been experimenting with treatments for what seems like ages now.
> 
> I have trouble getting a solid answer because all my speakers are electrostatics and nobody seems to have that much experience treating them and handling the back-wave.
> 
> I've attached a few pictures of the room and measurements from REW, ignore the A,B,C, etc red boxes in the room picture, the brown boxes are where the speakers are and I've also added wide channels at 60 degrees from the MLP.
> 
> What would you guys recommend? I can post more graphs later tonight, subs are placed at the B and C positions.
> 
> Thank you
> 
> http://imgur.com/a/l8Dmu
> 
> Dual Subs with Audyssey on:
> 
> http://i.imgur.com/KPflKGA.png


First thing I would do is flip the room to face the lower wall. That is going to give you much better symmetry which will result in better imaging. From there I would bass trap all the corners in your room, use diffusion for behind the speakers and early reflection points, and do a combination of diffusion/absorption on the back wall.


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## Nightlord

PrimeTime said:


> The nice thing about dipoles is that their radiation pattern usually nulls out some of the off-axis sound that would otherwise tend to produce the dreaded "early reflections."


Which also makes them ideal for placing close/against side walls if you have lack of space.

*still want to hear what IB-mounted Magnepans can do...i think it would be astounding...*

(FYI: have owned MG1.4:s somewhere back in time...)


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## ellisr63

Nightlord said:


> Which also makes them ideal for placing close/against side walls if you have lack of space.
> 
> *still want to hear what IB-mounted Magnepans can do...i think it would be astounding...*
> 
> (FYI: have owned MG1.4:s somewhere back in time...)


I remember years ago seeing an article where someone made a false wall and mounted some MLs in them.... They had a port in the wall for the backwave on each side of the MLs.


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## BB1111

myfipie said:


> First thing I would do is flip the room to face the lower wall. That is going to give you much better symmetry which will result in better imaging. From there I would bass trap all the corners in your room, use diffusion for behind the speakers and early reflection points, and do a combination of diffusion/absorption on the back wall.


Thank you for the response.

I currently do have 4x BAD RPG panels that I DIY'd a while ago, they are pretty nice made out of maple and I would like to incorporate them into the room if possible. Currently they are on the left and right wall at the first reflection points. Are these enough diffusion or should I move them to the back of the room and add true diffusers to the front of the room as you suggest? ( I would probably DIY the fractal diffuser from Arqen)

Also what benefit will the diffusers in front give me? What will it do to the sound field, imaging, characterstics of the speaker.. etc


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## badger985

*Owens corning "select sound" black acoustical board*

I was looking to make corner bass traps, and was going to buy Owens Corning 703 and cut them into the correct dimensions, however when doing research I found the following

Owens Corning "Select Sound" Black Acoustical Board 2" inch thick has an NRC of 1.00 the same as 703, but it also states that this reduces sound reverb, which 703 does not. Would this be a better product to create Bass Traps out of?

Please advise, I have tried doing research but I have found very little on these boards about this. Thank you.


Badger


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## myfipie

> but it also states that this reduces sound reverb, which 703 does not.


Both are going to reduce "reverb" in a room. Not sure what the density is of the other, but 4" 703 straddling the corner will work very well. If you plan on filling the corner then you want to use the less dense of the two.

NCR of 1 really does not tell you want it is doing on the low end, just what it is doing over all. Not a bad thing to look at but when looking at numbers you want to look at the low end test results vs the upper frequencies. Hope that makes sense.


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## coolgeek

I am looking to build a gentle diffusion.. and was thinking of using those 'vinyl tiles' that people use for flooring would work?

Do the vinyl absorb the sound or reflects them? If they absorb, then it won't work.

I was thinking of getting those and then bend them to semi-round... it's easy to build.. just put a bunch of them in right angles, bent into half round shapes... 

Basically something like below (contour type diffusers) but built out of vinyl floor tiles rather than wood:


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## BasementBob

badger985 said:


> I was looking to make corner bass traps, and was going to buy Owens Corning 703 and cut them into the correct dimensions, however when doing research I found the following
> 
> Owens Corning "Select Sound" Black Acoustical Board 2" inch thick has an NRC of 1.00 the same as 703, but it also states that this reduces sound reverb, which 703 does not. Would this be a better product to create Bass Traps out of?


 
To answer your last question first "Would this be a better product to create Bass Traps out of?"
No.
Please see: http://www.bobgolds.com/AbsorptionCoefficients.htm
look for 703, and compare it against Black Acoustic Board at {125hz, 250hz, 500hz, 1000hz, 2000hz, 4000hz}
There are lots of things very similar to 703, and anything that's similar is just fine.


The 'reverb' comment just seems odd to me. Either used correctly should take care of reverb. Either used insufficiently will not take care of reverb. A myriad of other things can be used to take care of reverb.


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## BasementBob

coolgeek said:


> I am looking to build a gentle diffusion.. and was thinking of using those 'vinyl tiles' that people use for flooring would work?
> 
> Do the vinyl absorb the sound or reflects them? If they absorb, then it won't work.
> 
> I was thinking of getting those and then bend them to semi-round... it's easy to build.. just put a bunch of them in right angles, bent into half round shapes...
> 
> Basically something like below (contour type diffusers) but built out of vinyl floor tiles rather than wood:


Vinyl will reflect some frequencies (higher f), and transmit (through it) other frequencies (lower f).
Generally speaking, anything more solid than 1/8" Masonite is ok as a diffuser.


The frequencies it has a hope of diffusing are proportional to the size of each.
The rule of thumb is:
- at wavelengths significantly smaller than the object, get defused as light bouncing off a curved mirror. 
- wavelengths significantly larger than the object, ignore the object
- wavelengths the same size as the object, reflect randomly.


With all of these being identical, spaced identically, you might get lobbing effects. Random sizes with random placement, give better diffusion.


----------



## badger985

BasementBob said:


> To answer your last question first "Would this be a better product to create Bass Traps out of?"
> No.
> Please see: http://www.bobgolds.com/AbsorptionCoefficients.htm
> look for 703, and compare it against Black Acoustic Board at {125hz, 250hz, 500hz, 1000hz, 2000hz, 4000hz}
> There are lots of things very similar to 703, and anything that's similar is just fine.
> 
> 
> The 'reverb' comment just seems odd to me. Either used correctly should take care of reverb. Either used insufficiently will not take care of reverb. A myriad of other things can be used to take care of reverb.


Great Thanks. 

Just to clarify the 703 FRK only has the foil reinforced on one side, thus if I slap that together with a regular piece of 703 2" to create a 4" trap, I will still get the benefit of the Foil Craft, and the enhanced Sound absorption at 125hz? 

Thanks again.


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## BasementBob

badger985 said:


> Just to clarify the 703 FRK only has the foil reinforced on one side, thus if I slap that together with a regular piece of 703 2" to create a 4" trap, I will still get the benefit of the Foil Craft, and the enhanced Sound absorption at 125hz?


 
Skip the FRK/foil. Membrane absorbers require an expert. If you understand how to make a membrane absorber, and how to measure/calculate the effects of existing wall resonance on the membrane, you're better than me. If you measure and discover you need a tuned membrane absorber to deal with a pesky room mode, look at a professional one like RPG Modex.


Mineral wool (including fiberglass), and corner traps, of just mineral wool and acoustically transparent cover fabric, are idiot proof.


1) soundproofing is good
2) knock first reflections down by at 20dB
3) deal with room modes. Minimalist techniques include tri-corner traps and subwoofer placement.
4) no chairs higher than your shoulders 
5) wide frequency absorption, not high frequency absorbers


----------



## bambam

Can someome give me a quick layman's explanation of what corner bass traps do - or help with - with the sound of the room? Does it reduce "boom" in the room? Anything else? Also, I imagine, if these are added to a room, you would probably have to re-run Audyssey XT32, correct?

Thanks!


----------



## Nightlord

Any acoustic treatment to a room warrants Audyssey to be re-run.


----------



## myfipie

bambam said:


> Can someome give me a quick layman's explanation of what corner bass traps do - or help with - with the sound of the room? Does it reduce "boom" in the room? Anything else? Also, I imagine, if these are added to a room, you would probably have to re-run Audyssey XT32, correct?
> 
> Thanks!


Bass Trapping will help with low end nulls and peaks, but also it will help with low end decay (think of this like reverb). If the low end decay is under control then the bass will be clearer and have much more punch. See the following video.
http://www.gikacoustics.com/video_bass-traps/


----------



## twain250

bambam said:


> Can someome give me a quick layman's explanation of what corner bass traps do - or help with - with the sound of the room? Does it reduce "boom" in the room? Anything else? Also, I imagine, if these are added to a room, you would probably have to re-run Audyssey XT32, correct?
> 
> Thanks!


Hi bambam,

Yes, it is highly recommended for you to re-run the Audyssey calibration after altering/improving your room's acoustic characteristics. Otherwise Audyssey will be attempting to make corrections for issues that either no longer exist or have been greatly changed -resulting in less than an optimum result from your acoustic improvements.

Cheers


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## BasementBob

bambam said:


> Can someome give me a quick layman's explanation of what corner bass traps do - or help with - with the sound of the room?


Superposition of waves: net amplitude caused by two or more waves traversing the same space is the sum of the amplitudes which would have been produced by the individual waves separately.

In a room, sound waves are created by speakers. The sound bounces off hard surfaces like walls, ceilings, and floors; resulting in superpositions with subsequent waves coming from the same speaker(s) tiny fractions of a second later.

Of the various reflective interference situations, one is 'room modal resonance'.
When the sound frequency's wavelength is an integer multiple of the room length, the reflected wave superpositions are in resonance (in phase), and build up to extremes.
Extremes that can eliminate a frequency at some spots in the room (nulls) and quadruple the volume of that frequency at other spots in the room (peaks).
Thus, two people sitting side by side, one might not hear a frequency at all (sitting in a null) and the next might find it booming (sitting in a peak).



















Although most reflections (other than room modal resonance) tend to be multiple angles like lasers off mirrored walls; the sound waves that make up axial modes (the primary room modal resonance) quickly settle down into back-front, or left-right, or up-down, directions. The room mode reflection is across the entire surface of the reflecting/opposing pair of walls (or floor/ceiling).

Corner traps have a couple of bits of physics and dollars in their favour
a) the diagonal shape of a corner trap uses little human usable space, yet is deeper than most wall absorbers are likely to be, that depth increasing the low frequency absorption
b) because its on a corner, it's involved in at least two axial modes directions (e.g. a vertical corner would affect the left-right and the front-back axial modes). Thus you're affecting multiple directional problems with a single purchase.
c) if you build the corner trap to completely fill the corner, then at least some of it is in a tri-corner (wall and ceiling and floor) thus hitting all three axial mode directions (up-down, left-right, front-back).

So, what you're trying to do with corner traps is knock down the strength of the reflecting wave at each reflection, thus reducing the resonant/superpositioned peaks and nulls, evening out the sound at more seating locations in the room.

Here's what a room looked like before corner traps 








and here's what it looks like after corner traps
Notice the reduction in peaks in the 30hz to 200hz range. 









Here's a waterfall version, before corner traps 








and after corner traps
Notice the reduction in the bottom axis. This represents a reduction in the time the sound is active in the room,
aka a reduction of the 'ringing' time/duration at that frequency,
caused by the corner traps absorbing a bit of each reflection. 









Because mineral wool (including fiberglass) porous absorber corner traps tend to be broadband absorbers (multi frequency) they automatically hit whatever modal frequencies happen to hit them. 

A tuned membrane absorber, on the other hand may waste a corner -- because its absorption is aimed at a specific single room mode (e.g. a front-back resonance), but multiple modes are active in corners (e.g. front-back and left-right), the space used by the tuned membrane absorber means that you can't simultaneously use the same space for treating other room modes (e.g. left right).

The frequencies of room modes can be somewhat predicted using a room mode calculator, that translates the integer multiple wavelengths based upon the room dimensions. e.g.
http://www.bobgolds.com/Mode/RoomModes.htm

I say 'somewhat' because walls are not perfect reflectors, so the frequencies tend to be near these, but not exactly. You can't tell until the room is built and full of stuff what needs to be treated.









http://forum.studiotips.com/viewtopic.php?f=8&t=536

superchunk









corner absorber


----------



## Nightlord

Problem is that the graphs show pressure and you really want to put that effort into where you have the maximum particle movement in the air, and those graphs are opposite. So the corner traps have to be big to expand enough out into the room to start having an effect on anything that's reasonably low. If you DO need pressure based absorbers, then corners are THE place for those. ( For particle movement, a heavy drape hanging a foot from the wall might be more efficient perhaps?)


----------



## xzener

Hello,

I am at the point where bass traps are next on the build list... Will cutting a 2X4 sheet of OC703 into 16 triangles and stacking them in the corners of the screen wall be OK?? Reason I ask is because my screen wall only has a 12 inch clearance behind it.

Thanks in advance!


----------



## myfipie

xzener said:


> Hello,
> 
> I am at the point where bass traps are next on the build list... Will cutting a 2X4 sheet of OC703 into 16 triangles and stacking them in the corners of the screen wall be OK?? Reason I ask is because my screen wall only has a 12 inch clearance behind it.
> 
> Thanks in advance!


Having the fiberglass in those corners should be fine, if I am understanding your question correctly. Basically all corners are good to use for bass trapping.


----------



## drblank

Ethan Winer said:


> JB,
> 
> I agree with Dennis that B is wrong. I'll go even further and say you should never cover any large surface area with material that absorbs the mids and highs. It makes the room too dead sounding, and does nothing to solve the inevitable low frequency problems. Much better is a mix of bass trapping and mid/high absorption, with no one area all live or all dead.
> 
> --Ethan


I've only heard of absorption, reflection and diffusion, what's this "Bass Trapping" nonsense? You aren't trapping any bass frequencies, either you are absorbing it or you aren't. Diaphragmatic membrane absorption systems work best for low frequencies below 100Hz, but they aren't "trapping" the bass frequencies, it's just another more effective way to absorb and control the bass, since typical midrange/high frequency absorption products don't work for the low frequencies under 100Hz, they work better for 125Hz and above, depending on the product and it's absorption curve.

Why people are so fixated on the words "bass trap" is more of a marketing term, it's kind of annoying.


----------



## Nightlord

drblank said:


> I've only heard of absorption, reflection and diffusion, what's this "Bass Trapping" nonsense? You aren't trapping any bass frequencies, either you are absorbing it or you aren't. Diaphragmatic membrane absorption systems work best for low frequencies below 100Hz, but they aren't "trapping" the bass frequencies, it's just another more effective way to absorb and control the bass, since typical midrange/high frequency absorption products don't work for the low frequencies under 100Hz, they work better for 125Hz and above, depending on the product and it's absorption curve.
> 
> Why people are so fixated on the words "bass trap" is more of a marketing term, it's kind of annoying.


What category would you place a tuned helmholz resonator into?


----------



## drblank

Nightlord said:


> What category would you place a tuned helmholz resonator into?


Another form of low frequency reduction. It works on a different principal to reducing low frequency pressure in a room than a diaphragmatic membrane absorption system. They are both used in dealing with low frequencies, but they work differently. Diaphragmatic membrane can be either tuned to a specific frequency range or they can be designed for more broadband low frequency depending on materials used and design.


----------



## myfipie

If you would like, you can read more about different kinds of Bass TRAPPING (ha ha) here.
http://www.gikacoustics.com/understanding-different-bass-trapping/


----------



## Ethan Winer

drblank said:


> Why people are so fixated on the words "bass trap" is more of a marketing term, it's kind of annoying.


The term bass trap has been used as far back as at least 1974, and probably even earlier, as you'll find in this back issue of dB magazine:

http://www.americanradiohistory.com/Archive-DB-Magazine/70s/DB-1974-09.pdf

Absorbing and trapping are basically the same thing. A mouse goes into a mouse trap and doesn't come out. Same for the Roach Motel. And again the same for bass entering a bass trap.

To call bass traps "nonsense" sounds more like trolling than adding to the discussion. Especially from an anonymous newbie in his very first post to this forum. 

--Ethan


----------



## drblank

Ethan Winer said:


> The term bass trap has been used as far back as at least 1974, and probably even earlier, as you'll find in this back issue of dB magazine:
> 
> http://www.americanradiohistory.com/Archive-DB-Magazine/70s/DB-1974-09.pdf
> 
> Absorbing and trapping are basically the same thing. A mouse goes into a mouse trap and doesn't come out. Same for the Roach Motel. And again the same for bass entering a bass trap.
> 
> To call bass traps "nonsense" sounds more like trolling than adding to the discussion. Especially from an anonymous newbie in his very first post to this forum.
> 
> --Ethan



It's not really a "technical" term, it's more of a "marketing" term and there are a lot of people out there that confuse what it actually means.

Tthey aren't trapping they are ABSORBING. I know the industry has used that term, but that doesn't mean it's an accurate term.

Real Traps has Mondo Traps, does that mean they trap Mondos? Or MegaTraps trapping Megas? Or MicroTraps trapping Micros?

Serious Ethan, i think your argument is kind of, well, silly.

Why can't people call a low frequency absorption system a low frequency absorption system, just like they call Diffusors diffusors? Is there anything wrong with asking people to refer to acoustic treatment as to what it does rather than making up some term because it sounds good? Not all acoustic engineers refer to low frequency absorption systems as bass traps. Some dislike using the term.

The problem that's commonly occurring is that there are companies out there, without naming names because that's not important, refer to products as bass traps, but they are always absorbing low frequencies, they are absorbing midrange frequencies.


----------



## drblank

myfipie said:


> If you would like, you can read more about different kinds of Bass TRAPPING (ha ha) here.
> http://www.gikacoustics.com/understanding-different-bass-trapping/


Why are you trying to push your products on a web forum? Isn't that kind of cheesy way to market your products rather than discussing a topic of discussion? The topic of discussion is not referring to your products specifically, is it?


----------



## myfipie

> Why are you trying to push your products on a web forum? Isn't that kind of cheesy way to market your products rather than discussing a topic of discussion? The topic of discussion is not referring to your products specifically, is it?





It is talking about different kinds of TRAPPING vs you just coming on here to stir the pot. Ethan is 100% correct about the term BASS TRAP if it *annoys* you or not.  Hate to see what real problems do to you if the term "bass traps" ANNOYS you so much. ha ha


----------



## drblank

Ethan Winer said:


> The term bass trap has been used as far back as at least 1974, and probably even earlier, as you'll find in this back issue of dB magazine:
> 
> http://www.americanradiohistory.com/Archive-DB-Magazine/70s/DB-1974-09.pdf
> 
> Absorbing and trapping are basically the same thing. A mouse goes into a mouse trap and doesn't come out. Same for the Roach Motel. And again the same for bass entering a bass trap.
> 
> To call bass traps "nonsense" sounds more like trolling than adding to the discussion. Especially from an anonymous newbie in his very first post to this forum.
> 
> --Ethan


Whatever Ethan.

Coming from someone that makes MegaTraps, MondoTraps and MicroTraps, that really says it all. There are no Mondos, Megas, or Micros in room acoustics.

:facepalm:


----------



## LeBon

drblank said:


> Whatever Ethan.


And WHATEVER, DrBlank. Get a life...


----------



## Mike Lang

Move on guys...


----------



## Jay5298

*Question about FRK paper*

This subject has been talked about a lot I know, but I have some questions. I am putting the OC 703 2" panels I have on my wall on my ceiling, and making thicker 3 inch panels to put in there place. They have about an inch of air gap. I've read that you should not use the FRK paper facing the room for reflection panels. I have also read that if you use the FRK paper on the ceiling facing the room it can help "give back" a little HF taken by the carpeting on the floor, sort of evening things out. How much extra LF absorption would I get if I put the FRK paper facing the ceiling and the wall on the side wall panels given that I have about an inch of air gap. Would it make that much of an improvement or is it a waste of time. I am also building a large 4 inch thick trap to put on my back wall between my surround speakers. Does it make sense to put FRK paper on this to help LF. My back row of seats is about 4 ft away from the wall and my front row is about 9 to 10 ft away.
Thanks


----------



## coolgeek

Speaking of using different materials in DIY diffusors. I can't afford those nice $1000 dollar rounded made of wood diffusors so I was thinking, can I use 'window coping' materials? There are some that are sort of rounded... on the outside they are cementitious but inside is just styrofoam... Good or Bad idea?


----------



## detzx

For people searching. You can get OC 703 (Owens Cornings 703) at Kamco Supply Corp in Woburn MA. It was $108 for 12 2x4 pieces as of 7/19/14.


----------



## myfipie

> I have also read that if you use the FRK paper on the ceiling facing the room it can help "give back" a little HF taken by the carpeting on the floor, sort of evening things out.




If the panel are in the early reflection area on the ceiling then you do not want to use FRK.




> How much extra LF absorption would I get if I put the FRK paper facing the ceiling and the wall on the side wall panels given that I have about an inch of air gap. Would it make that much of an improvement or is it a waste of time.


I actually "re-treated" a studio a number of years ago that had 2" panels with the FRK on the back that was spaced off the wall. We replaced them with just normal two inch panels with a gap and that seemed to work much better. I think the FRK was not letting enough sound through the FRK to hit the wall, but instead reflecting back like it was a bare wall. Needless to say I would not recommend it.


----------



## myfipie

> I have also read that if you use the FRK paper on the ceiling facing the room it can help "give back" a little HF taken by the carpeting on the floor, sort of evening things out.




If the panel are in the early reflection area on the ceiling then you do not want to use FRK.




> How much extra LF absorption would I get if I put the FRK paper facing the ceiling and the wall on the side wall panels given that I have about an inch of air gap. Would it make that much of an improvement or is it a waste of time.




I actually "re-treated" a studio a number of years ago that had 2" panels with the FRK on the back that was spaced off the wall. We replaced them with just normal two inch panels with a gap and that seemed to work much better. I think the FRK was not letting enough sound through the FRK to hit the wall, but instead reflecting back like it was a bare wall. Needless to say I would not recommend it.


----------



## ellisr63

myfipie said:


> If the panel are in the early reflection area on the ceiling then you do not want to use FRK.
> 
> 
> 
> 
> 
> 
> I actually "re-treated" a studio a number of years ago that had 2" panels with the FRK on the back that was spaced off the wall. We replaced them with just normal two inch panels with a gap and that seemed to work much better. I think the FRK was not letting enough sound through the FRK to hit the wall, but instead reflecting back like it was a bare wall. Needless to say I would not recommend it.


I was thinking of putting 9 2'x4' 2" thick Roxul R80 rockport sheets up for our ceiling... They will be first reflection points for the first and second row. Should I face them with paper since we have carpeted floors?


----------



## myfipie

ellisr63 said:


> I was thinking of putting 9 2'x4' 2" thick Roxul R80 rockport sheets up for our ceiling... They will be first reflection points for the first and second row. Should I face them with paper since we have carpeted floors?



No, you never want to use facing on the panels if in the early reflection point. 

http://www.gikacoustics.com/video-early-first-reflection-points/


----------



## Jay5298

Thanks Glenn,

What do you think about the back wall? I have two columns about 5 feet apart with dipole speakers inside the columns. I was going to put 4 inch thick OC 703 between the columns and put the FRK facing on so I don't absorb too much of the sound from the dipole speakers. I still want the sound to reflect a little.


----------



## nexxest

My A0 poster of my cat:


----------



## ellisr63

myfipie said:


> No, you never want to use facing on the panels if in the early reflection point.
> 
> http://www.gikacoustics.com/video-early-first-reflection-points/


Thanks, I was getting confused from your earlier qoute... Now I understand.


----------



## xzener

myfipie said:


> Having the fiberglass in those corners should be fine, if I am understanding your question correctly. Basically all corners are good to use for bass trapping.


Thanks Myfipie, 

Just want to clarify before cutting up all this expensive OC703... I am cutting them into 16 triangles, as opposed to the popular 8 pieces.

This is OK yes??


----------



## myfipie

> Just want to clarify before cutting up all this expensive OC703... I am cutting them into 16 triangles, as opposed to the popular 8 pieces.


That is going to be pretty small and is not going to work all that great below 200hz or so. I recommend making the triangles no less then 16"x16"x24" honestly.


----------



## coolgeek

Ready to buy Roxul and Pink Fluffy. I got a few important questions before committing a lot of money to it.

1. Should I get 40, 60 or 60 KG/M3?
2. Pink Fluffy (glass wool). This if for under the Riser (as a general bass trap). I intend to fill it all up, about 6 feet in length and 10 feet wide, and 1 feet high. Again, people say get pink fluffy/glass wool instead of RockWool, so, again, the question, would 30 KG/M3 work?


----------



## ellisr63

I am looking to make some bass traps for my rear wall in my HT. The wall is 15' wide, and I was thinking of using Roxul RX60 3" thick with 2 layers... Is this a good way to go?


----------



## Nightlord

ellisr63 said:


> I am looking to make some bass traps for my rear wall in my HT. The wall is 15' wide, and I was thinking of using Roxul RX60 3" thick with 2 layers... Is this a good way to go?


6" thick won't do much bass trapping. It'll probably rather have great influence on everything except the bass, so it's still not a bad idea.


----------



## ellisr63

Nightlord said:


> 6" thick won't do much bass trapping. It'll probably rather have great influence on everything except the bass, so it's still not a bad idea.


I should have said I will also have a 1' x 2' soffit also all around the room for bass traps, plus in 2 of the corners behind my AT screen. I hope i will have enough.


----------



## Nightlord

ellisr63 said:


> I should have said I will also have a 1' x 2' soffit also all around the room for bass traps, plus in 2 of the corners behind my AT screen. I hope i will have enough.


Much better. No riser for back seats that you can use as well?


----------



## ellisr63

Nightlord said:


> Much better. No riser for back seats that you can use as well?


We have a riser, but the way it was built we can't use it for a bass trap. If need be, we might be able to get a couple of feet of depth behind the front speakers to make a bass trap 19' wide x 8' tall. Currently I was planning on 2" Roxul R80 for the whole wall behind the screen. How do I know when I have enough?


----------



## Nightlord

ellisr63 said:


> How do I know when I have enough?


That's easily answered - you never have enough basstrapping.  You'll just have to use your ears and any measurement equipment available to decide when you're content.


----------



## PoshFrosh

myfipie said:


> Having the fiberglass in those corners should be fine... Basically all corners are good to use for bass trapping.


What about a corner that ends and opens into a room after about a foot or two? *Would it make sense to place a bass trap where the red line is in my room diagram attached?* Or is that not considered a "corner" for the purpose of bass trapping?


----------



## myfipie

PoshFrosh said:


> What about a corner that ends and opens into a room after about a foot or two? *Would it make sense to place a bass trap where the red line is in my room diagram attached?* Or is that not considered a "corner" for the purpose of bass trapping?


Those corners would work. They are pretty much at the end of the wall/ceiling/floor boundaries.


----------



## Nightlord

PoshFrosh said:


> What about a corner that ends and opens into a room after about a foot or two? *Would it make sense to place a bass trap where the red line is in my room diagram attached?* Or is that not considered a "corner" for the purpose of bass trapping?


Sure. And if you do symmetrically the same in the other front corner, you'd get a really big one - and a nicer look.

If I read the plan correct, you have a big opening in the side and also no door before the staircase? I'd try hang some heavy drapes there, I think that could have noticable effect too.


----------



## ellisr63

How do you attach ceiling panels? I have a double drywall with green glue and hat channel ceiling. I was thinking of using these, but I am not sure they can handle the weight of 2'x4'x4" Acoustic panels. If I use toggle screws then I have to penetrate the double drywall, and will loose the benefit of the soundproofing won't I?


----------



## myfipie

Those are made for walls, not ceiling so I would not recommend them. I always use butterfly/toggle screws.


----------



## Laidback

Didn't have time to read all 348 pages prior, but I did read a decent amount to catch up. Finally getting the room dubbed "Theater Room" for the past 13 years together! Starting from the ground up. It is on the second floor so floor joists as the floor. Starting with carpet and working up. Any suggestions on padding or carpet types? Also had a question on the use of draped fabric for the ceiling. Would it work to have a thicker fabric draped from pole to pole kind of a thing. As it hangs it would arch down towards the floor and also be somewhat bunched up rather than pulled tight? Thanks! Looking over the GIK Acoustics site too.
Jon


----------



## Laidback

Didn't have time to read all 348 pages prior, but I did read a decent amount to catch up. Finally getting the room dubbed "Theater Room" for the past 13 years together! Starting from the ground up. It is on the second floor so floor joists as the floor. Starting with carpet and working up. Any suggestions on padding or carpet types? Also had a question on the use of draped fabric for the ceiling. Would it work to have a thicker fabric draped from pole to pole kind of a thing. As it hangs it would arch down towards the floor and also be somewhat bunched up rather than pulled tight? Thanks! Looking over the GIK Acoustics site too.
Jon


----------



## myfipie

Why do you need fabric on the ceiling? Are you covering up fiberglass?


----------



## Laidback

I was reading on here were guys were talking about putting curtains on the walls to help with sound absorption/diffusion. (not sure of proper terms yet) I have a sloped ceiling that starts at 5'6" at the front and goes up at an 8:12 pitch to 12'. Then it runs flat for approx 12' and then back down to the 5'6" in the back. I was thinking the curtain type fabric would help knock down anything bouncing off of the ceiling. Or I could just be wrong, which it ok. Just seemed like a decently cheap solution that I could do myself. Still trying to get this all figured out.


----------



## Nightlord

If you can have the curtains a foot from the wall, all the better. It doesn't do much flat on the wall.


----------



## TRIPTON80

I am getting ready to re-buy new acoustic panels. I bought a 6 pack of 703 a while back and was getting ready to throw them up, even built the frames. Then my wife started researching 703. She does not want to have anything to do with it. So I started doing my research. I am looking at Audimute Eco panels, which seem to be expensive and they are 1.5 inches thick. Their sites states it ha better absorption then 703. I am also looking at Knauf and wondering if it just as bad as703. It is definitely cheaper then the Audimute stuff. Any thoughts as they are having sales online today so I'd like to figure it out soon. Thank you


----------



## rprice54

I'm working on a supply list for my theater room. Going to put in corner traps up front, I don't see many folks trapping the back corners, any particular reason not to?


----------



## HopefulFred

The more low frequency absorption you have, the better. If it's feasible to put absorption in the rear corners, it's a good idea. Generally, people who don't are making a compromise based on available space and other uses for that space.


----------



## zheka

If I have subs placed in the corners , should I have the bass traps only above the subs or have them all the way, floor to ceiling? I suspect that the bottom part of the corners where the subs are should be left naked but I am not sure. What would you recommend?


Thanks


----------



## HopefulFred

I personally think that if the rear corners are the best place for your subs - or for whatever reason the only place for your subs - then treat around them as you can. Ceiling to subs sounds good. More experienced folks may disagree, but I think placement for smooth response is a more powerful tool than trapping for smooth response.


----------



## zheka

HopefulFred said:


> I personally think that if the rear corners are the best place for your subs - or for whatever reason the only place for your subs - then treat around them as you can. Ceiling to subs sounds good. More experienced folks may disagree, but I think placement for smooth response is a more powerful tool than trapping for smooth response.


Thank you for the reply. The subs are not all the way in the corners, there is enough room for the trap. 
I am asking what the best practice is. Should I have the traps fully cover the corners or only from the subs up? 
These are front corners if it matters.


----------



## HopefulFred

If there is space available for a trap, use it.  The proximity to the sub doesn't change anything.


----------



## Jacob B

myfipie said:


> Both are going to reduce "reverb" in a room. Not sure what the density is of the other, but 4" 703 straddling the corner will work very well. If you plan on filling the corner then you want to use the less dense of the two.
> 
> NCR of 1 really does not tell you want it is doing on the low end, just what it is doing over all. Not a bad thing to look at but when looking at numbers you want to look at the low end test results vs the upper frequencies. Hope that makes sense.


Does that mean best practice in the first decade of the millinium, of making "super chunk corner traps" cutting OC703 in 17x17x24" triangles and stacking them, is not recommended any more?
Should I use lesser dense/rigid material than oc703 for a super chunk?

In one rear corner, I need a removable bass trap (there's a small door for accessing the roof), and I was thinking making a 2'x5'x 4" OC703 filled wooden frame straddling the corner, rather than a superchunk. Would that work?

Thanks! 
Jacob


----------



## myfipie

> I am also looking at Knauf and wondering if it just as bad as703. It is definitely cheaper then the Audimute stuff. Any thoughts as they are having sales online today so I'd like to figure it out soon. Thank you


We actually use Knauf and love it! And for it working YES! You can view our lab numbers of our products on each product page and also the following, that has a lot to do with Knauf.
http://www.gikacoustics.com/greensafe/


----------



## myfipie

Jacob B said:


> Does that mean best practice in the first decade of the millinium, of making "super chunk corner traps" cutting OC703 in 17x17x24" triangles and stacking them, is not recommended any more?
> Should I use lesser dense/rigid material than oc703 for a super chunk?
> 
> 
> 
> Thanks!
> Jacob


There has been further testing (by us and others) done at labs over the years that have shown less dense, when making a panel (or filling the corner) will work better. But 703 stacked in the corner does also work pretty well. 



> In one rear corner, I need a removable bass trap (there's a small door for accessing the roof), and I was thinking making a 2'x5'x 4" OC703 filled wooden frame straddling the corner, rather than a superchunk. Would that work?


You can do that and it will work well.


----------



## Jacob B

Thanks Glenn! 
I guess I will make the front wall 2" treatment and side wall 6" FRP panels (with 2" air gap) first, using OC703, and then, if my aquired OC703 material runs out, use lesser dense fiberglass for the corner traps. 

For the removeable corner trap, which will have the large air gap behind the 4" panel, should that also be lesser dense material - and leave the denser OC703 for panels close to the wall? 

Best,
Jacob


----------



## Jacob B

*Ecose vs. 6 year old OC703 ?*



myfipie said:


> We actually use Knauf and love it! And for it working YES! You can view our lab numbers of our products on each product page and also the following, that has a lot to do with Knauf.
> http://www.gikacoustics.com/greensafe/


I have had 6 boxes of OC703 stored for six years, due to HT construction pause... Since then, the market appears to be moving to more indoor environment friendly products, like Knauf's Ecose line. 
I am wondering whether the long storage period might have allowed the OC703 to degaz the formaldehyde used in the binder or whether they still will pollute the air in my HT if used for acustic treatment?

*Would I be better of trying to sell it and buy some of the Knauf Ecose fiberglass sheets?* Not least since I haven't made any panels yet?

If so, *which products should I buy for replacing OC703 for 2-4" next-to-wall treatments and which product for the superchunk corner traps?* I guess the Ecobatt would be for the cornertraps? Despite its low density, can it be used as a replacement all over for OC703?
It does not seem that Knauf's more rigid fiberglas is made with Ecose?


----------



## myfipie

Jacob B said:


> I have had 6 boxes of OC703 stored for six years, due to HT construction pause... Since then, the market appears to be moving to more indoor environment friendly products, like Knauf's Ecose line.
> I am wondering whether the long storage period might have allowed the OC703 to degaz the formaldehyde used in the binder or whether they still will pollute the air in my HT if used for acustic treatment?
> 
> *Would I be better of trying to sell it and buy some of the Knauf Ecose fiberglass sheets?* Not least since I haven't made any panels yet?
> 
> If so, *which products should I buy for replacing OC703 for 2-4" next-to-wall treatments and which product for the superchunk corner traps?* I guess the Ecobatt would be for the cornertraps? Despite its low density, can it be used as a replacement all over for OC703?
> It does not seem that Knauf's more rigid fiberglas is made with Ecose?


To match up with 703 you would want to use 3 pound. For the filled corners use something like 1.6 pound.


----------



## rprice54

Anybody with reasonable shipping? I just tried to make an order for two packages of roxul 60 and 5 yards of fabric and the shipping was over $100!!!


----------



## ellisr63

What is the preferred method of attaching insulation to the wall behind a AT screen... I have R19 Denim.


----------



## Jacob B

myfipie said:


> To match up with 703 you would want to use 3 pound. For the filled corners use something like 1.6 pound.


Thanks! Would I also use the 1.6 pund stuff for 6" FRP panels (4" fiberglass with 2" air gap) ?



Jacob B said:


> I have had 6 boxes of OC703 stored for six years, due to HT construction pause... Since then, the market appears to be moving to more indoor environment friendly products, like Knauf's Ecose line.
> I am wondering whether the long storage period might have allowed the OC703 to degaz the formaldehyde used in the binder or whether they still will pollute the air in my HT if used for acustic treatment?
> 
> *Would I be better of trying to sell it and buy some of the Knauf Ecose fiberglass sheets?* Not least since I haven't made any panels yet?


No advice on the environmental thing? - would the worst be over with the six year old OC703, or does the age make no difference on the formaldehyde issue?


----------



## myfipie

> No advice on the environmental thing? - would the worst be over with the six year old OC703, or does the age make no difference on the formaldehyde issue?


Sorry I can't be any help there. I really do not know. 



> Thanks! Would I also use the 1.6 pund stuff for 6" FRP panels (4" fiberglass with 2" air gap) ?


You could but I for DIY'ing I would use 3 pound.


----------



## myfipie

> No advice on the environmental thing? - would the worst be over with the six year old OC703, or does the age make no difference on the formaldehyde issue?


Sorry I can't be any help there. I really do not know. 



> Thanks! Would I also use the 1.6 pund stuff for 6" FRP panels (4" fiberglass with 2" air gap) ?


You could but I for DIY'ing I would use 3 pound.


----------



## Jacob B

*6" vs. 4"+2" ?*

Effect pr. dollar not considered, which type of 6" DIY "full range" absorption panel for mounting on the wall has the best effect in the bass / lowest mid region:

*1.* 4" of 3 pcf fiberglass + 2" built-in airgap behind the fiberglass?
*2.* 6" of 3 pcf fiberglass + 0" of airgap behind?

Most talk is about optimizing absorption with *a given amount of fiberglass materiel*, but I cant seem to find data on optimizing the porous/air ratio for *a given panel thickness*.
http://www.bobgolds.com/AbsorptionCoefficients.htm only has data on 0 vs 16" air gap, which in most small rooms only seems relevant for corner traps.

Jacob


----------



## myfipie

> 1. 4" of 3 pcf fiberglass + 2" built-in airgap behind the fiberglass?
> 2. 6" of 3 pcf fiberglass + 0" of airgap behind?


6" for sure.. Fiberglass absorbs more then air.


----------



## Jacob B

myfipie said:


> 6" for sure.. Fiberglass absorbs more then air.


Thanks for your answer!
So when people talk about air gaps always being better than no gap, it is always with the assumption that the amount of porous absorbing materiel is given/constant, I guess? 

How come the GIK scatter plates dont alter the bass absorption qualities of the panel it is mounted on? If they dont alter the depth, they must take space from the fiberglass in the panel? Or am I missing something?


----------



## GIK Acoustics

Jacob B said:


> Thanks for your answer!
> So when people talk about air gaps always being better than no gap, it is always with the assumption that the amount of porous absorbing materiel is given/constant, I guess?
> 
> How come the GIK scatter plates dont alter the bass absorption qualities of the panel it is mounted on? If they dont alter the depth, they must take space from the fiberglass in the panel? Or am I missing something?


It does compress the insulation a slight bit..but the fabric also expands on the front and back with the addition of a Scatter Plate. And the Scatter Plate isn't incredibly thick, so the amount of change the material undergoes is quite slight, only about 1/4" or less compression. As such, the effect it has is negligible.


----------



## PoshFrosh

Wowzah. I used to think WAF didn't exist (for me) as I've been doing all sorts of HT stuff in our new house. But I was in hot water yesterday after I put up some (GiK) acoustical treatment without running it by her first.

I treated the front corners, the side first reflections, and the rear wall. Too much, apparently. We negotiated a bit... The rear wall panel has to go. The rest, may be okay with some slight modifications. I got to learn first hand how "easy" it is to "ask for forgiveness" (vs. permission). Phew.


----------



## Jacob B

*Black cork in rear half of HT?*

Anyone with experience on using other materiel than carpet in the rear half of the home theater?

*Since my entire ceiling has 4" OC703 (between the joists), I am considering whether to avoid using a black carpet in the entire room, and maybe go for a harder surface in the rear half, behind the first reflection zone. *

The idea is that it might create a more lively room. It is a dedicated home theater room, but I will most likely retreat to the room to play stereo musik as well. Might be forced to experiment with multichannel music modes, I guess. We will see.
My living room is much larger and very lively sounding, with oak wooden floors (a rug in front of speakers). I kind of like it lively for music - it is what I am used to, anyway 

One idea is using *black cork* (30 cm squares 3.2 mm thick) glued to the OSB floor (double 1/2" OSB w/ GG, on a 10 mm rubber matt on the original pine plank floor), from the first row of seats and back, including on the floor of the riser for 2nd row. 

Besides the acoustic difference, it would also be more cleaning friendly, as opposed to carpet where people (e.g. kids) are sitting with their popcorn, soda, beer, snacks etc. 

*To understand my acoustic layout, this is my current plan (ceiling is already done):*
- The room is 20.5' x 12.5' x 8' with angled walls starting 5.5' up. Walls are DD with GG.
- A false wall will hold the AT screen 3 feet from the 2" rigid fiberglass treated front wall. 
- All four wall-wall corners will have super chunk (17x17x24", rear wall) or soffit (12x31" rectangle, front wall) bass traps with fluffy fiberglass from floor up to the height of the angled walls (5½ feet). 
- Front wall will also have a soffit type 12x12" trap at the wall-ceiling and wall-floor corners.
- First reflection zone on side walls will be treated with 6" rigid fiberglass from floor to 4'
- Rear wall will have 3 GIK monster traps with FRT and scatter panels and two GIK versifusors higher up flanking the rear surrounds and the projector. 
- The angled side walls will have 8" wide 3' high panels (2" OC703 w/ 1½" air gap) alternating with 8" of no treatment, from AT screen to first row. 
- From 1st row and back to rear wall, the angled walls will have 4 GIK versifusors in each side, with 4" rigid fiberglass treatment at the top 10" (the ceiling-side wall corner).

Hope to hear from some of you that have experienced with different floor types 

Cheers,
Jacob


----------



## ellisr63

PoshFrosh said:


> Wowzah. I used to think WAF didn't exist (for me) as I've been doing all sorts of HT stuff in our new house. But I was in hot water yesterday after I put up some (GiK) acoustical treatment without running it by her first.
> 
> I treated the front corners, the side first reflections, and the rear wall. Too much, apparently. We negotiated a bit... The rear wall panel has to go. The rest, may be okay with some slight modifications. I got to learn first hand how "easy" it is to "ask for forgiveness" (vs. permission). Phew.


I pretty much do what I want for the HT... I negotiated with my wife when we bought the house that I got the Garage, HT, and a Pond. The way it is now going is, I have the Pond, and the HT has moved to the Garage (my decision not hers). When I need another opinion on colors in the room, I ask her for her input, and she has been 100% supportive (up until a couple of months ago she was not a happy camper though seeing all the $$$ going into it, but now that she sees it is almost completed she loves it).


----------



## GIK Acoustics

Since your ceiling is entirely treated, adding wood floor to the rear of the room won't increase flutter echo - and since your ears will likely be obstructed by the seats you won't have a lot of direct reflections coming in to interfere with the direct signal as much. And in the rear of the room, where ambient reflections can help decrease localization of the surrounds, I would bet you'd like the result for not just two channel but theater as well. As most carpets used are not broadband absorptive, a reflective floor with a fully absorptive ceiling is actually much more often preferred than a carpeted room!


----------



## Nightlord

Just be aware that you'll most likely need to have in-ceiling speakers for Atmos then - bouncing Atmos-enabled speakers of an absoptive ceiling is not a good idea...


----------



## pletwals

Jacob B said:


> Effect pr. dollar not considered, which type of 6" DIY "full range" absorption panel for mounting on the wall has the best effect in the bass / lowest mid region:
> 
> *1.* 4" of 3 pcf fiberglass + 2" built-in airgap behind the fiberglass?
> *2.* 6" of 3 pcf fiberglass + 0" of airgap behind?
> 
> Most talk is about optimizing absorption with *a given amount of fiberglass materiel*, but I cant seem to find data on optimizing the porous/air ratio for *a given panel thickness*.
> http://www.bobgolds.com/AbsorptionCoefficients.htm only has data on 0 vs 16" air gap, which in most small rooms only seems relevant for corner traps.
> 
> Jacob


From what I have been reading: filling up 6" with 6" material will always have a little bit more effect. Still, 4" plus a 2" plenum with 50% more surface (same volume of material) will be more effective still...


----------



## Dizzy49

ellisr63 said:


> I pretty much do what I want for the HT... I negotiated with my wife when we bought the house that I got the Garage, HT, and a Pond. The way it is now going is, I have the Pond, and the HT has moved to the Garage (my decision not hers). When I need another opinion on colors in the room, I ask her for her input, and she has been 100% supportive (up until a couple of months ago she was not a happy camper though seeing all the $$$ going into it, but now that she sees it is almost completed she loves it).


I'm in the same boat. Everything in the basement is mine (theater, office, full bath, server room, laundry room, and a spare bedroom) to do whatever I want with. The rest of the house is hers. Unfortunately whenever I ask her opinion on things I always get, "It's your space, you can do whatever you want with it." THEN she got pissed when I hired a designer to help me. Damned if you do, damned if you don't, right? Right now she's onboard with the theater as it gets the entertainment center out of her living room  Though now she is seeing how much money is going into my office (basically a mini theater), and is having second thoughts. I'm going to see if we can get a Home Equity loan to redo the kitchen and floors upstairs for her so I can finish the theater how I want on the down low


----------



## ellisr63

Dizzy49 said:


> I'm in the same boat. Everything in the basement is mine (theater, office, full bath, server room, laundry room, and a spare bedroom) to do whatever I want with. The rest of the house is hers. Unfortunately whenever I ask her opinion on things I always get, "It's your space, you can do whatever you want with it." THEN she got pissed when I hired a designer to help me. Damned if you do, damned if you don't, right? Right now she's onboard with the theater as it gets the entertainment center out of her living room  Though now she is seeing how much money is going into my office (basically a mini theater), and is having second thoughts. I'm going to see if we can get a Home Equity loan to redo the kitchen and floors upstairs for her so I can finish the theater how I want on the down low


My wife is anxious to get the living room back since it will no longer be the theater. I am down to the 2 rooms that i wanted... HT, and pond room.


----------



## Al Sherwood

ellisr63 said:


> I pretty much do what I want for the HT... I negotiated with my wife when we bought the house that I got the Garage, HT, and a Pond. The way it is now going is, I have the Pond, and the HT has moved to the Garage (my decision not hers). When I need another opinion on colors in the room, I ask her for her input, and she has been 100% supportive (up until a couple of months ago she was not a happy camper though seeing all the $$$ going into it, but now that she sees it is almost completed she loves it).





Dizzy49 said:


> I'm in the same boat. Everything in the basement is mine (theater, office, full bath, server room, laundry room, and a spare bedroom) to do whatever I want with. The rest of the house is hers. Unfortunately whenever I ask her opinion on things I always get, "It's your space, you can do whatever you want with it." THEN she got pissed when I hired a designer to help me. Damned if you do, damned if you don't, right? Right now she's onboard with the theater as it gets the entertainment center out of her living room  Though now she is seeing how much money is going into my office (basically a mini theater), and is having second thoughts. I'm going to see if we can get a Home Equity loan to redo the kitchen and floors upstairs for her so I can finish the theater how I want on the down low



The Three Musketeers? I also have a similar arrangement, the HT and work shop are mine, still in very rough stages and full of crap, but... after 5 years working over the main floor including a complete kitchen gut and replace (removed 2 walls), refinishing all hardwood floors, new windows, doors, paint and lighting I can almost see the end, possibly by the end of September!


Next up, my spaces, I might do the shop first so I can build the DTS-10's and stuff for the HT, as now I need to provision for Dolby Atmos!


----------



## ChldsPlay

I'm looking at getting an acoustic treatment design, and from what I gather some of these treatments can be somewhat deep. How exactly are these covered up on the wall? I was looking at using a track system like fabricmate, but most of those seem to be designed for one or 2 inches. 

Also, how do you deal with this extra depth at a doorway? You'd have at least 4" of depth to cover on the side I would think.

What is the best track system to use for this?


----------



## ChldsPlay

I'm looking at getting an acoustic treatment design, and from what I gather some of these treatments can be somewhat deep. How exactly are these covered up on the wall? I was looking at using a track system like fabricmate, but most of those seem to be designed for one or 2 inches. 

Also, how do you deal with this extra depth at a doorway? You'd have at least 4" of depth to cover on the side I would think.

What is the best, and most cost effective, track system to use for this?


----------



## myfipie

> I'm looking at getting an acoustic treatment design, and from what I gather some of these treatments can be somewhat deep. How exactly are these covered up on the wall? I was looking at using a track system like fabricmate, but most of those seem to be designed for one or 2 inches.


Most people just hang them on the wall like a picture or use something freestanding or a stand.


----------



## myfipie

> I'm looking at getting an acoustic treatment design, and from what I gather some of these treatments can be somewhat deep. How exactly are these covered up on the wall? I was looking at using a track system like fabricmate, but most of those seem to be designed for one or 2 inches.


Most people just hang them on the wall like a picture or use something freestanding or a stand.


----------



## 911turbojk

Guys 

If my LEFT/ SIDE / BACK and ceiling are all treated with Acoustic Materials ( Combination of Absorption+ Diffusion ) ,, will it be alright for me to use HARDwood floor in the HT room ? 

The issue is that I also prefer carpet, but the wife is very worried about the carpet that might cause allergy issue to our 2 year old down the road. 
( Since the room is dedicated , always closed ) and plus all the fiberglass panels around the wall,,, 

So she is asking me to see if we can possibly use hardwood floor instead ( Oak)


----------



## HopefulFred

911turbojk said:


> ...will it be alright for me to use HARDwood floor in the HT room ?


I think there is plenty of reason to be very happy with hardwood floor. Consider a few things we know about acoustics and carpet. Carpet, even with the most absorbent properties and most absorbent pad, will not perform as a broadband absorber. A well-designed absorber on the ceiling could provide absorption much lower in frequency, meaning that it makes better use of itself - centering its absorption in the midrange and hopefully down into the bass region. Carpet is also often cited as helping with the response anomalies associated with "floor bounce" (the SBIR or Alison effect frequency response problem created by the first reflection of sound from the floor) but I think a careful look will show that carpet is not very effective here. Better results would probably come from choosing a speaker with better controlled dispersion in the vertical plane.

It seems that you are being fairly careful with your acoustic considerations, so I say proceed with confidence and endeavor to keep your treatments appropriately placed throughout the room and their frequency response profiles centered on areas of real concern.

Fred


----------



## ChldsPlay

myfipie said:


> Most people just hang them on the wall like a picture or use something freestanding or a stand.


I was looking to do something more like this:



or this:


----------



## Jacob B

*Leg rest covers 1st reflections?*



HopefulFred said:


> I think there is plenty of reason to be very happy with hardwood floor. Consider a few things we know about acoustics and carpet. Carpet, even with the most absorbent properties and most absorbent pad, will not perform as a broadband absorber. A well-designed absorber on the ceiling could provide absorption much lower in frequency, meaning that it makes better use of itself - centering its absorption in the midrange and hopefully down into the bass region. Carpet is also often cited as helping with the response anomalies associated with "floor bounce" (the SBIR or Alison effect frequency response problem created by the first reflection of sound from the floor) but I think a careful look will show that carpet is not very effective here. Better results would probably come from choosing a speaker with better controlled dispersion in the vertical plane.
> 
> It seems that you are being fairly careful with your acoustic considerations, so I say proceed with confidence and endeavor to keep your treatments appropriately placed throughout the room and their frequency response profiles centered on areas of real concern.
> 
> Fred


I will have a planned viewing distance of 10 feet from the first row to a 9 feet wide cinemascope AT screen.
When sitting reclined in the Berkline 090s in the first row, the leg rest will cover the first reflections on the floor from the LCR speakers, and the 1st row seats will cover the FRZ for the second row...
In this case, ceiling treatment or not, would carpet or a rug between the screen and the first row have any beneficial impact at all? 
It would seem that all it would do would be deaden the room with no positive effects to show for the downside? The only positive effect I can think of would be potentially less light reflection fron the floor to the screen, from black carpet as opposed to black-colored oak hardwood floor (oiled).

Anyone? Suggestions?


----------



## ellisr63

Jacob B said:


> I will have a planned viewing distance of 10 feet from the first row to a 9 feet wide cinemascope AT screen.
> When sitting reclined in the Berkline 090s in the first row, the leg rest will cover the first reflections on the floor from the LCR speakers, and the 1st row seats will cover the FRZ for the second row...
> In this case, ceiling treatment or not, would carpet or a rug between the screen and the first row have any beneficial impact at all?
> It would seem that all it would do would be deaden the room with no positive effects to show for the downside? The only positive effect I can think of would be potentially less light reflection fron the floor to the screen, from black carpet as opposed to black-colored oak hardwood floor (oiled).
> 
> Anyone? Suggestions?


I would think that oiled hardwood is going to give you a lot of light reflection... I would at least use a dark carpet for the first few feet from the screen.


----------



## Jacob B

So my acoustical considerations are okay, then?

I will try to test the shine in advance. I can always place a 2-3 feet wide dark rug on tje hardwood to fix a shine.


----------



## HopefulFred

That's my assessment.


----------



## tjenkins95

I have a home theater and the ceiling is made up of sound absorbing "ISC Black Cinetile Matte" acoustical 24" by 24" tiles from http://www.iscsupply.com . I recently bought a Denon AVR-5200w with Dolby Atmos sound along with a set of the new Andrew Jones Pioneer Elite Dolby Atmos enabled up-firing speakers. The up-firing speakers require a reflective ceiling so that the sound will bounce off the ceiling.
So, I need to replace a couple of my panels with reflective ones. It was recommended that I purchase 1/2" foam core but I would like to use pre-cut ceiling panels.
I checked online at Lowes and Home Depot and they have a variety of 24" by 24" ceiling panels but from reading the descriptions none of them specifcially say "sound reflective." There is one type - Armstrong 16-Pack Oasis Homestyle Ceiling Tile Panel (Common: 24-in x 24-in; Actual 23.704-in x 23.704-in) with a description of "Smooth plaster finish with a 3-dimensional look." Do you think those would work? Anyone have experience with these ceiling tiles and can make some recommendations?
 Thanks.


----------



## BasementBob

tjenkins95:


I would imagine that the rules are similar to those for "Definitive Technology bi-polar" speakers -- namely that you aim the 'unusually radiating speaker' (i.e. the ones out the back) at drywall. (reflective, rather than diffusive)


All materials have {absorptive, reflective, transmissive} qualities. 
Reflectors tend to be like rock. 
Concrete, being rock like, is a great reflector {low absorptive, low transmittive, high reflective}.
Next up in reflectors are sheetrock (aka drywall).


False ceiling tiles of fiberglass or foam wouldn't be my first choice for reflectors.


My first guess is you have four alternatives:
a) [reflective] make your own ceiling tiles out of drywall
b) [reflective] make your own ceiling tiles out of 3/4" plywood
c) [diffusive] make a diffusive reflector, poly shaped, made from 1/2 inch or more thick {heat warped plastic/plexiglass, laminated wood, or fiberglass}, and hang it from the ceiling above your speakers. (see below (c))
d) [diffusive] google for and purchase a "ceiling tile sound diffuser". There are several of them out there. e.g. RPG Harmonix-K ceiling tile 











(c) Like one of these:








http://www.btconline.co.uk/index.php/home/image:154/acoustics


Alternatively, of course, you can:
a) ignore it
b) measure its effects and treat any actual problem
c) disconnect the up firing drivers
d) something else


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## tjenkins95

Thanks for the feedback. Dolby Atmos upfiring-speakers require a reflective surface so out of the four alternatives:


a) [reflective] make your own ceiling tiles out of drywall
b) [reflective] make your own ceiling tiles out of 3/4" plywood


are both good options.


----------



## AXLCMT

Just wrote this all up and then lost it.  Here it goes for the second attempt... 


I performed a search on this thread for the words "behind the screen", hoping to find any posts with regards to my need to know if I should put Base Trapping (most likely OC703 unless you guys suggest a cheaper alternative to save me some ???) *BEHIND* my *SOLID* Screen *(not acoustically transparent/fabric)*. 

I planned on buying Base Trapping for the entire front screen wall, plus the sides of the room up until "ear height" and the Cotton Batting from the "ears up". 

So the question is, is it the "law of diminishing return" with regards to putting "base trapping/OC703" BEHIND the SOLID Screen if I am base trapping the entire screen wall??? 

I know that if you have an "acoustically transparent screen" you automatically put base trapping behind the screen, but what about for a solid screen? 

I hope your answers are "no" to save me some $$$ when it comes to base trapping square footage. My screen is 160" 2.35:1 Jamestown 1.2 gain. 

Thanks.


----------



## AXLCMT

Also, regarding Base Trapping and OC703. Is OC703 the most expensive? 

I am on a very limited budget and I am looking for cheapest "alternative" to OC703
and trying to stay away from those "high end" brands that cost $$$. 

Any suggests?


----------



## ellisr63

AXLCMT said:


> Also, regarding Base Trapping and OC703. Is OC703 the most expensive?
> 
> I am on a very limited budget and I am looking for cheapest "alternative" to OC703
> and trying to stay away from those "high end" brands that cost $$$.
> 
> Any suggests?


I am using Roxul R60 on my wall behind the AT screen... I believe it is less expensive than the OC703.


----------



## nickbuol

Depending on how far from the wall to your back of your screen, you will never get much real BASS (spelled like the fish, or guitar, or type of low frequency sound, but pronounced like home base, or the guitar, or the low frequency sound  ) trapping. You need some good thickness to it, but it would seem that what you want to do is just prevent the wall and the back of the solid screen from becoming a big drum with sound bouncing all around back there.

How much space is between your wall and the back of your screen?

Also, you talk about bass trapping all around your room up to ear height, again, I think that there are some terms getting confused here since you would have quite the massive treatment all around the room where it wouldn't provided a good effect.

Bass traps *generally* just go in wall/wall corners, floor to ceiling to start, then can go into soffits, or along ceiling/wall and floor wall corners. Combating room resonance, reflection points, and so forth happen all around the room, like floor to ear height, etc. I am sure that I am not getting the terms exactly right either, thus my vague description, but it will be easier to get solid advice from the experts here if you at least know that bass trapping isn't an entire wall behind a screen, or floor to ear height around the room so that they can provide the best advice to you.

OC703 is a tried and true material, but as mentioned there are cheaper alternatives that yield similar results like the Roxul 60. A lot of people cover their entire front wall with linacoustic, but again, that is for acoustically transparent applications mainly. I've heard of good results with the "cotton denim insulation" as well, but you need to make a frame for it since it isn't rigid at all.

Again, come back with the distance between the wall and the back of the screen, and people can start helping you eliminate your issues there, then you can look at treating the walls with absorption, diffusion, reflection combinations.


----------



## AXLCMT

nickbuol said:


> Depending on how far from the wall to your back of your screen, you will never get much real BASS (spelled like the fish, or guitar, or type of low frequency sound, but pronounced like home base, or the guitar, or the low frequency sound  ) trapping. You need some good thickness to it, but it would seem that what you want to do is just prevent the wall and the back of the solid screen from becoming a big drum with sound bouncing all around back there.
> 
> How much space is between your wall and the back of your screen?
> 
> Also, you talk about bass trapping all around your room up to ear height, again, I think that there are some terms getting confused here since you would have quite the massive treatment all around the room where it wouldn't provided a good effect.
> 
> Bass traps *generally* just go in wall/wall corners, floor to ceiling to start, then can go into soffits, or along ceiling/wall and floor wall corners. Combating room resonance, reflection points, and so forth happen all around the room, like floor to ear height, etc. I am sure that I am not getting the terms exactly right either, thus my vague description, but it will be easier to get solid advice from the experts here if you at least know that bass trapping isn't an entire wall behind a screen, or floor to ear height around the room so that they can provide the best advice to you.
> 
> OC703 is a tried and true material, but as mentioned there are cheaper alternatives that yield similar results like the Roxul 60. A lot of people cover their entire front wall with linacoustic, but again, that is for acoustically transparent applications mainly. I've heard of good results with the "cotton denim insulation" as well, but you need to make a frame for it since it isn't rigid at all.
> 
> Again, come back with the distance between the wall and the back of the screen, and people can start helping you eliminate your issues there, then you can look at treating the walls with absorption, diffusion, reflection combinations.


Thanks Nick. With regards to the distance between my SOLID screen and the screen wall, if I didn't put Bass Trapping behind the screen, then the screen would be directly contacting the screen wall, ie there would be not distance at all between the screen wall and screen. (no false wall here etc.) Yes, I planned on Bass Trapping all around the room up until ear height, then Cotton Batting from ear height to the ceiling.


----------



## AXLCMT

nickbuol said:


> Bass traps *generally* just go in wall/wall corners, floor to ceiling to start, then can go into soffits, or along ceiling/wall and floor wall corners. Combating room resonance, reflection points, and so forth happen all around the room, like floor to ear height, etc. I am sure that I am not getting the terms exactly right either, thus my vague description, but it will be easier to get solid advice from the experts here if you at least know that bass trapping isn't an entire wall behind a screen, or floor to ear height around the room so that they can provide the best advice to you.


Thanks Nick about the Bass Trapping advice. So, what then goes from Ear Height to the floor if not Bass Trapping?


----------



## nickbuol

AXLCMT said:


> Thanks Nick. With regards to the distance between my SOLID screen and the screen wall, if I didn't put Bass Trapping behind the screen, then the screen would be directly contacting the screen wall, ie there would be not distance at all between the screen wall and screen. (no false wall here etc.) Yes, I planned on Bass Trapping all around the room up until ear height, then Cotton Batting from ear height to the ceiling.


A know that a lot of people put nothing behind their screen and just mount it directly on the wall. I can only speculate that a number of these people don't care about acoustical treatments, and the others feel that if the screen material is thick enough, that it will just reflect sound anyway and putting something behind the screen wouldn't yield the performance that they want.

With a solid screen, you are going to reflect higher frequencies, so if you put anything back there, it will only be for lower frequencies and bass trapping, and to do that you will need some really thick material or thick material and an air gap. At a minimum you would need 4" of acoustical insulation and a good sized air gap, but that is just starting to get into bass trapping thicknesses. 8" of insulation (OC703, Roxul 60, or similar) and some air gap for real bass trapping.

However....

You still aren't doing bass trapping like you think you are. Corners, corners, corners... That is where you get the biggest improvement from bass trapping, plus you aren't covering an entire wall with 8" of material (everything gets expensive at that point), and losing about a foot of depth just on the front wall for something that isn't going to do what you think that it is. Yes, if you did that to the entire front wall, it would provide trapping in the corners, but why pay for all of that material??

Bass trapping is only 1 part of the acoustical treatment process. You are using the term "bass trapping" for ALL parts of acoustical absorption.

Maybe you really want to put 8" of insulation around your room, but I am certainly not recommending that to anyone without some sort of measurement that would justify it, and even then I can't imagine what kind of room would need all of that.


----------



## nickbuol

AXLCMT said:


> Thanks Nick about the Bass Trapping advice. So, what then goes from Ear Height to the floor if not Bass Trapping?



Again, bass trapping requires a LOT of space (really at least 12") which just isn't very good "bang for your buck," plus takes a lot of space. You want general acoustical treatments, of which bass trapping is one piece, but it is best left for corners where it has the most positive impact on the sound in the room.

The basic, "I don't want to do room measurements" approach to absorption (there is also reflection and diffusion which are both good too) is to use 1" of OC703 in some areas and 2" of OC703 in others along the bottom half of the room (some people use 1" all around or 2" all around the bottom half of the wall, but a mix should get rid of the high rings and echos from the 1", and tame some of the more mid-level echo that is harder to hear, but muddies the audio in a room). You can make the frames all 2" and just alternate 1" and 2" insulation since you are going to have to cover it all with acoustically transparent fabric anyway and won't see the different thicknesses. Then you put your cotton batting up above if you want, but keep in mind that while cotton batting doesn't absorb as well as the material in the lower half of the wall, it still impacts the sound in the room, and you don't want to over absorb either. I would leave some of the space on the top half of the wall with nothing but solid wall behind the fabric to make it so that the room doesn't go completely dead.

Still. Doing all of this is still going to cost some money. At some point, the difference between the acoustical insulation products becomes less and less important to the total cost of the project.


----------



## AXLCMT

nickbuol said:


> Again, bass trapping requires a LOT of space (really at least 12") which just isn't very good "bang for your buck," plus takes a lot of space. You want general acoustical treatments, of which bass trapping is one piece, but it is best left for corners where it has the most positive impact on the sound in the room.
> 
> The basic, "I don't want to do room measurements" approach to absorption (there is also reflection and diffusion which are both good too) is to use 1" of OC703 in some areas and 2" of OC703 in others along the bottom half of the room (some people use 1" all around or 2" all around the bottom half of the wall, but a mix should get rid of the high rings and echos from the 1", and tame some of the more mid-level echo that is harder to hear, but muddies the audio in a room). You can make the frames all 2" and just alternate 1" and 2" insulation since you are going to have to cover it all with acoustically transparent fabric anyway and won't see the different thicknesses. Then you put your cotton batting up above if you want, but keep in mind that while cotton batting doesn't absorb as well as the material in the lower half of the wall, it still impacts the sound in the room, and you don't want to over absorb either. I would leave some of the space on the top half of the wall with nothing but solid wall behind the fabric to make it so that the room doesn't go completely dead.
> 
> Still. Doing all of this is still going to cost some money. At some point, the difference between the acoustical insulation products becomes less and less important to the total cost of the project.


Thanks Nick. What about *Linacoustic* instead of Bass Trapping OC703? (for the surrounding areas outside of the screen frame on the screen wall and also from floor to ear height on the side walls). 

What about the entire rear wall? Bass Trapping for the entire rear wall?
(that is what I thought Dennis Erskine and Bryan Pape keep advising)

I will follow your advice and put the Bass Trapping OC703 in the corners though.


----------



## nickbuol

AXLCMT said:


> Thanks Nick. What about *Linacoustic* instead of Bass Trapping OC703? (for the surrounding areas outside of the screen frame on the screen wall and also from floor to ear height on the side walls).
> 
> What about the entire rear wall? Bass Trapping for the entire rear wall?
> (that is what I thought Dennis Erskine and Bryan Pape keep advising)
> 
> I will follow your advice and put the Bass Trapping OC703 in the corners though.


Linacoustic is a commonly used product for the front wall (usually behind an acoustically transparent screen and false wall).

As for treating the back wall, again, the bass trap term has somehow poisoned your mind. LOL. I don't mean that as an insult, just teasing. Someone, somewhere gave you that term and didn't clarify it for you.

There are several schools of thought. Dead end/live end (with the front wall treated which is the dead end of the room, and then nothing but bass trapping in corners for the back of the room which is the live end), dead end/dead end (with both front and rear walls completely treated). Again, if you are going to treat the bottom half of the walls with 1" and/or 2" acoustical insulation, just do that around the back walls too.

Now, these are all general statements. Dennis and Bryan would both tell you that you need to measure your room with an acoustical microphone to map out the problem areas before applying any treatments to make sure that you are treating the exact problems that your exact room has. We are trying to solve unknown room acoustic problems with a broad stroke brush here. My statements are just meant as an approach without measuring your room, but the best results come from an acoustical analysis and treating the specific needs.... however, that costs more money too, thus my general statements.

Oh, and Dennis himself will tell you that every room is different and he won't generally give generic advice because he wants to give accurate advice (which is good), but that requires measuring the sound in a room. Here is an interview from a few days ago with Dennis.


----------



## coolgeek

I have a question about bass vibrating the concrete walls around my basement bunker and that transfers the bass out of that room into the room upstairs from it or throughout the entire house (as the concrete walls / brick walls are all interconnected).

My idea is to stick a thin rubber sheet on all walls (those they use for carpet underlay type, about 3mm thick), floor, and ceiling... in my mind, when the bass frequency hits that rubber, much of it's vibrations would be stopped by the rubber and it won't transfer to the concrete... 

Am I right? or would i just be wasting my time...?


----------



## coolgeek

I have a question about bass vibrating the concrete walls around my basement bunker and that transfers the bass out of that room into the room upstairs from it or throughout the entire house (as the concrete walls / brick walls are all interconnected).

My idea is to stick a thin rubber sheet on all walls (those they use for carpet underlay type, about 3mm thick), floor, and ceiling... in my mind, when the bass frequency hits that rubber, much of it's vibrations would be stopped by the rubber and it won't transfer to the concrete... 

Am I right? or would i just be wasting my time...?


----------



## Syllogistic

Hi everyone. I am completely new to room treatment and currently my room is completely untreated. I'm just not sure where to even start. I've got a Studio EQ mic and have measured the frequency response of the speakers in the room as they are currently positioned. It looks pretty bad so I don't even know where to begin! The room is made of concrete, about 4.1 metres by 4.5 metres, attached to an open kitchen (around 2 metres by 2 metres) and a hallway. The speakers are currently around 0.5 metres out from a corner.

Any advice / starting points would be appreciated.


----------



## thestoneman

I am getting close to buttoning everything up and I'm starting to grow more concerned about how the sound is going to behave in this space. One photo shows my screen wall. The other photo shows the opposite end of the room, which will be a traditional bar area.

I am open to comments/suggestions/etc. I just assume make changes, if necessary, to ensure I don't create any "fatal" acoustic conditions.

Room dimensions are 14' x 35'.


----------



## Nightlord

coolgeek said:


> I have a question about bass vibrating the concrete walls around my basement bunker and that transfers the bass out of that room into the room upstairs from it or throughout the entire house (as the concrete walls / brick walls are all interconnected).
> 
> My idea is to stick a thin rubber sheet on all walls (those they use for carpet underlay type, about 3mm thick), floor, and ceiling... in my mind, when the bass frequency hits that rubber, much of it's vibrations would be stopped by the rubber and it won't transfer to the concrete...
> 
> Am I right? or would i just be wasting my time...?


If you're right, then you've just solved a problem that everyone else before you have gone to great lengths to combat. Does that seem plausible?


----------



## myfipie

Syllogistic said:


> Hi everyone. I am completely new to room treatment and currently my room is completely untreated. I'm just not sure where to even start. I've got a Studio EQ mic and have measured the frequency response of the speakers in the room as they are currently positioned. It looks pretty bad so I don't even know where to begin! The room is made of concrete, about 4.1 metres by 4.5 metres, attached to an open kitchen (around 2 metres by 2 metres) and a hallway. The speakers are currently around 0.5 metres out from a corner.
> 
> Any advice / starting points would be appreciated.


See the following to give you a hand on getting started.
http://www.gikacoustics.com/basics-room-setup-acoustic-panels-bass-traps/


----------



## Digital Ace

coolgeek said:


> I have a question about bass vibrating the concrete walls around my basement bunker and that transfers the bass out of that room into the room upstairs from it or throughout the entire house (as the concrete walls / brick walls are all interconnected).
> 
> My idea is to stick a thin rubber sheet on all walls (those they use for carpet underlay type, about 3mm thick), floor, and ceiling... in my mind, when the bass frequency hits that rubber, much of it's vibrations would be stopped by the rubber and it won't transfer to the concrete...
> 
> Am I right? or would i just be wasting my time...?


That is a big problem! right here. Since everything is concrete its all reflective and i highly doubt that a think rubber sheet of 3mm thickness could do anything. I would suggest you to look at something like acousticblok or maybe 9mm neoprene. I guess that should work.


----------



## archiguy

I'm building a theater with an AT screen (Falcon, woven) over 3 Triad Bronze 4" in-walls and was wondering how to treat the screen wall. Don't really want to cover it with insulation; not sure that's necessary. Thinking instead about a thick triple-black velvet, same stuff I will extend out about 3' from the screen on all four walls.

Comments?


----------



## coolgeek

Digital Ace said:


> That is a big problem! right here. Since everything is concrete its all reflective and i highly doubt that a think rubber sheet of 3mm thickness could do anything. I would suggest you to look at something like acousticblok or maybe 9mm neoprene. I guess that should work.


Thanks Digital Ace... that's very helpful...


----------



## ellisr63

archiguy said:


> I'm building a theater with an AT screen (Falcon, woven) over 3 Triad Bronze 4" in-walls and was wondering how to treat the screen wall. Don't really want to cover it with insulation; not sure that's necessary. Thinking instead about a thick triple-black velvet, same stuff I will extend out about 3' from the screen on all four walls.
> 
> Comments?


I don't think it will do much except deaden your highs a little... Much better to make some acoustic bass trap panels for the wall behind the screen, and then cover the panels in a black material in my opinion.


----------



## archiguy

ellisr63 said:


> I don't think it will do much except deaden your highs a little... Much better to make some acoustic bass trap panels for the wall behind the screen, and then cover the panels in a black material in my opinion.


Thanks for the reply. So, it's back to Linacoustic, aka black duct liner? That's a fairly large project; not sure how I'd go about attaching that material to the wall. And how do you attach the fabric to it? 

Don't want to go to that kind of expense and trouble if the improvement will be marginal, or perhaps not even noticeable. Won't the high frequencies from the Triad in-wall loudspeakers pass through the woven screen straight to my ears "unmolested"? Isn't that the whole point of a [woven] acoustically transparent screen?


----------



## ellisr63

archiguy said:


> Thanks for the reply. So, it's back to Linacoustic, aka black duct liner? That's a fairly large project; not sure how I'd go about attaching that material to the wall. And how do you attach the fabric to it?
> 
> Don't want to go to that kind of expense and trouble if the improvement will be marginal, or perhaps not even noticeable. Won't the high frequencies from the Triad in-wall loudspeakers pass through the woven screen straight to my ears "unmolested"? Isn't that the whole point of a [woven] acoustically transparent screen?


I think the Linacoustic is available in black (no need to cover). The reason for treating the wall behind the AT screen are: 
1: Prevent light reflection from your projector
2: Prevent the returning sound waves from your surrounds and sub from mixing in with your front channels sound waves.


----------



## archiguy

What's the best way to attach the Linacoustic to the back wall (painted drywall on 2x6's at 16" O.C.)...?


----------



## cgott42

How is rigid foam - like this?
I have some extra 2" boards (thinking I can glue together to make 4") and want to treat my baseboard (where floor and wall intersect) behind the front speakers (also perhaps in a ceiling/wall intersection above the speakers)


----------



## ellisr63

archiguy said:


> What's the best way to attach the Linacoustic to the back wall (painted drywall on 2x6's at 16" O.C.)...?


I believe that some people are using screws (long), and fender washers... I have also seen some screws and washers made specifically for it but I can't remember where.


----------



## myfipie

cgott42 said:


> How is rigid foam - like this?
> I have some extra 2" boards (thinking I can glue together to make 4") and want to treat my baseboard (where floor and wall intersect) behind the front speakers (also perhaps in a ceiling/wall intersection above the speakers)


That sort of foam has NO acoustic value at all to it. Basically it would be waste of funds. Look for rigid fiberglass or mineral wool. If using foam then you want open celled foam and honestly don't look for it to do wonders. Most of the "real" acoustic foam is to thin or small to be all that effective.
http://www.gikacoustics.com/comparing-foam-to-gik-244-bass-traps/


----------



## Jacob B

*Need OC703 rigid fiberglass in Europe?*

If any Northern Europeans are interested in OC703, I have 5 boxes of 2" rigid fiberglass boards for sale in the classified section:

http://www.avsforum.com/forum/216-a/1737593-oc703-rigid-fiberglass-europe.html#post28568137


----------



## Maklar

myfipie said:


> That sort of foam has NO acoustic value at all to it. Basically it would be waste of funds. Look for rigid fiberglass or mineral wool. If using foam then you want open celled foam and honestly don't look for it to do wonders. Most of the "real" acoustic foam is to thin or small to be all that effective.
> http://www.gikacoustics.com/comparing-foam-to-gik-244-bass-traps/


Would using foam over insulation impact the effectiveness of the insulation? I want to do tufted acoustic panels and thought of using foam over the insulation to help keep the rigidity of the tufts.


----------



## thestoneman

*DIY Schroeder diffuser panels*

I have access to a CNC router and I am planning DIY Schroeder panels. Does anyone have dimensions I can use so my material is deep enough and cuts are affective?

Also, any thoughts on the effectiveness using expanded PVC (Sintra) with a painted finish?


----------



## BasementBob

thestoneman said:


> DIY Schroeder panels. Does anyone have dimensions I can use so my material is deep enough and cuts are affective?


knowing there were online calculators for this out there, I googled.
This is the first one I found
http://www.subwoofer-builder.com/qrdude.htm
(There are skyline numbers elsewhere)


----------



## thestoneman

BasementBob said:


> knowing there were online calculators for this out there, I googled.
> This is the first one I found
> http://www.subwoofer-builder.com/qrdude.htm
> (There are skyline numbers elsewhere)


Awesome. Thanks!


----------



## hv9200

Hello All, 

great thread and tons of info here...really hard to read all through it so I thought I could ask a basic question.

I have received a couple of recommendations for my theater room (one open wall into larger room) from GIK and Realtraps and they both essentially recommended that I add a few bass traps to the corners of the room and line my closed wall with HF absorption panels to make up for the open side, I am looking to make some DIY panels and have poster images printed onto AT fabric. The question I have is what material differentiates the LF panels from the HF panels...is it just thickness? I am looking at the OC 703 material and am unsure if that is a bass trap of a HF absorber...

sorry if this is answered in the thread somewhere, I did a few searches and came up with just too much info to sort through.


----------



## Jacob B

If no alucraft on the OC 703, only thickness decides frequency band of the absorption. 1" = HF, 4" = broadband absorption (only little Low level bass unless panel is placed in corner).

For effective absorption below 125 Hz, you need more than 12" (or some sort of membrane in front of the fiberglass), which is why such panels normally are placed in corners.

HF only is generally not recommended - broadband is preferred. 
Add an airgap behind the fiberglass if the budget cannot afford enough OC703, but space is available for a thicker panel.

Cheers,
Jacob


----------



## hv9200

Jacob B said:


> If no alucraft on the OC 703, only thickness decides frequency band of the absorption. 1" = HF, 4" = broadband absorption (only little Low level bass unless panel is placed in corner).
> 
> For effective absorption below 125 Hz, you need more than 12" (or some sort of membrane in front of the fiberglass), which is why such panels normally are placed in corners.
> 
> HF only is generally not recommended - broadband is preferred.
> Add an airgap behind the fiberglass if the budget cannot afford enough OC703, but space is available for a thicker panel.
> 
> Cheers,
> Jacob


Thanks Jacob, just so I understand you correctly, a HF only panel would be 1" and a broadband is 4"...and even at 4" (w/o alucraft) the LF benefits are only realized if corner placed? 

that being said, for my room, I should use 4" 703 for the side wall, and 4" 703 for the corners to cover both some HF and some LF corner trapping?


----------



## Jacob B

Basically, yes to all 
HF only is generally not recommended for small room acoustics. However, it used to be (8-10 years ago) standard treatment in home theatre for sidewalls up to ear height.
For the corners, you could also make a "super chunk" corner trap, which basically is a 4'x2' fiberglass panel cut in either 4 or 8 triangles and stacked in the corners from floor to ceiling. Front it with a small frame with AT fabric. You could use cheaper fluffy type fiberglass for the super chunks rather than the OC703. Knauf Ecose fiberglass is a good indoor environment friendly product for that. They also make more rigid, OC703 equivelant, fiberglass or mineral wool.


----------



## asarose247

Ceiling Treatments changes?
Now that ATMOS puts the speakers IN or ON the ceiling
what sort of challenges do the more experienced / knowledgeable room measurers/ treaters expect , if anything, to be addressed
I ask this as I expect to use on -ceiling speakers, aimed at the MLP, 42 inches ahead, behind and left and right of the MLP, within angle suggestions , a 7 foot square
Would a cloud of OC703 2" or 3" roxul an inch or 2 from the ceiling help in the reduction of HF or even broadband reflections off the ceiling from the outer edges or the speakers dispersion characteristics (at least the "top half") ?
could this add some clarity and clearer separation between TF's and TR's , i.e. directing more on axis sound at the MLP?, yet still allowing the ATMOS "bubble " to envelop?
you can see how this evolves to then maybe having a angled cloud over the surrounds, maybe even the rears, if you go for 7.x.4
reduced peripheral HF reflections that "lift and separate" yet allow a measureablt satisfactory unified ATMOS or DSU envelope.
I realize this is a new wrinkle/take on what is already a huge/well known/much discussed/strongly individual circumstances subject but as I contemplate the info wrt to finally selecting and AVR, 
I would like to be prepared to hear insights about what the resident experts think the problems might be, how to define or recognize them and the sources and what might be done to measure the results of various treatment suggestions.
It's a lot I know but this is the place to at least ask, for a start


Thank you


----------



## myfipie

Maklar said:


> Would using foam over insulation impact the effectiveness of the insulation? I want to do tufted acoustic panels and thought of using foam over the insulation to help keep the rigidity of the tufts.


Hard closed foam will actually reflect so I would not recommend it.


----------



## thestoneman

Here is a SketchUp file that I can export to my CNC router. My plan is to make deflection panels out of 2" thick HDU foam with a painted finish. The square dimensions are 3" x 3". 

Anyone see any issues?


----------



## asoofi1

thestoneman said:


> Here is a SketchUp file that I can export to my CNC router. My plan is to make deflection panels out of 2" thick HDU foam with a painted finish. The square dimensions are 3" x 3".
> 
> Anyone see any issues?


This makes me wish I had a CNC machine. What kind of install are you doing?


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## HopefulFred

Why not extend the bandwidth and improve the pattern with a proper 2D QRD?


----------



## thestoneman

HopefulFred said:


> Why not extend the bandwidth and improve the pattern with a proper 2D QRD?


How much depth do I need for a good 2D diffuser? I was going to place diffusers on the ceiling in front of the screen and on the back wall.

To be honest, I just started messing with the idea of building diffusers and don't know all that much about them...including where they should be located for best effect.


----------



## HopefulFred

Really, the first questions should be, "Do I need diffusion?" and "Why?" Diffusion is a good addition to most listening rooms, I'd wager. But, as you suggest, "where" is the hard part. Diffusion acts to redirect and delay reflected energy with minimal energy loss, compared to plain absorption. So, without knowing anything about the energy decay in your room we can't say with much confidence. Still, we can make some generalizations, I suppose (though I am not by any means the most qualified to do so).

Diffusion of some sort is often recommended for first reflection points on side walls and ceilings. If the room size, speaker location, and seating position lead to a very high gain set of early reflections it might be most appropriate to absorb or pursue a hybrid design that both absorbs and diffuses. Or maybe 2D diffusion reduces the gain enough to maintain the purity of the direct speaker signal (if that is what you want) by redirecting and delaying the energy's arrival at your listening position. Or you might find that 1D diffusion does a better job of letting you enjoy the wide soundstage that your speakers might create. See how there's lots of options? The choice hinges on several things: room size; speaker location; seating location; speaker dispersion/off-axis performance; content (stereo vs multi-channel music vs home theater); and last-but-perhaps-most-important - preference. (Have I confused this enough? Go back to the first sentence of this paragraph.)

The details of all those parameters (especially speaker design and location details) would suggest the bandwidth you might need for diffusion. Once that is known, you can start to compromise and fail to meet that need, most likely (nice, huh?). 

The bandwidth of most diffusors is defined by the depth of the deepest wells (the difference between the tallest and shortest sections) and the width of the wells (the 3x3 you indicated in your design). In order to extend diffusion to lower frequencies the wells should be made deeper. In order to extend the high frequency limit upward, the wells should be narrower. Once those two features are defined, you need to determine the pattern that fits in your space and that you can build - it's not random.

The whole process can be a little daunting and gets pretty complex. Here's a link with some good background reading links that you maybe haven't seen: https://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/482372-1d-2d-qrd-diffusor.html As a practical matter, it might be simplest to combine your needs and desires and basic understanding with the compromises you can identify in popular commercial products, and emulate them.


----------



## thestoneman

My goal is not to create a perfect sounding room, but experiment with some treatments to improve the room acoustics using trial and error. I don't pretend to know the black science that is room acoustics. My hope is that messing around with diffusion and absorption treatments will net a room that sounds pleasant. 

That said, sounds like increasing the cell depth is something I should be doing. HDU foam can be stacked easily to make a 3" deep material. I am trying to avoid creating a dead room, but want to help Audyessy out as much as I can.


----------



## HopefulFred

thestoneman said:


> That said, sounds like increasing the cell depth is something I should be doing.


I think so.

I hope I didn't seem to be talking down to your or around you. It's hard to communicate the right tone and the right details for the audience sometimes. It might be worth you starting your own thread to discuss your plans and your results.


----------



## myfipie

Fred gave you some GREAT advice.. Perhaps it might be best for you to list more info about your room, pictures and so on. It might be that diffusion really is not the answer to your room. BTW what kind of CNC router do you have?


----------



## thestoneman

myfipie said:


> Fred gave you some GREAT advice.. Perhaps it might be best for you to list more info about your room, pictures and so on. It might be that diffusion really is not the answer to your room. BTW what kind of CNC router do you have?


My company has (2) Multi-Cam machines capable of routing on 3 axes. 

Here is a photo of the room (view from where the bar will be). The basics are, 14' x 35' space with one end being the screen wall and the other end will be a full/traditional built in bar area. NOTE: The riser is NOT set in place yet.

I plan to add diffuser panels on the ceiling between the MLP and the screen and absorption panels scattered/staggered on the walls.


----------



## thestoneman

HopefulFred said:


> I think so.
> 
> I hope I didn't seem to be talking down to your or around you. It's hard to communicate the right tone and the right details for the audience sometimes. It might be worth you starting your own thread to discuss your plans and your results.


Not at all...totally appreciate the fact that you are trying to help me. I hope I didn't come across as being unappreciative. Fact is, all I know about sound waves is that they bounce off of surfaces in varying wavelengths. I am admittedly "wingin' it" here so criticism is more than welcome!

I'll definitely consider the 3" depth...I've looked at QRD calculators and know that more depth is better. My ceiling is 7'-10.5" so I'm concerned about aesthetics, but 3" should be fine.


----------



## memmo

I need to pick up some insulation to use as bass traps behind my false wall and I'm having difficulty sourcing OC703 (or any of the equivalents) locally. I can find them about an hour a way, but since I need a bunch (and have a small hatchback) it would require multiple trips. Before I do that, I've read that many folks up here in Canada have been using Roxul Comfortboard IS as it is easily available at Home Depot. I'm curious to know how it compares in density (and ultimately effectiveness) to the 703. Basically, how do I make sense of the numbers below?

Here's a link: http://www.homedepot.ca/product/roxul-r6-comfortboard-is-insulated-sheathing-board-for-basement-and-exterio/995375


Here's a comparison -- using info I found from a technical data sheet I found on Roxul's site.

*OC 703 (3")*
125HZ - 0.53
250HZ - 1.19
500HZ - 1.21
1000HZ -1.08
2000HZ - 1.01
4000HZ - 1.04
NRC - 1.10


*Roxul Comfortboard IS (3")*
125HZ - 0.75
250HZ - 0.82
500HZ - 0.89
1000HZ - 0.94
2000HZ - 1.00
4000HZ - 1.00
NRC - .90


----------



## BasementBob

memmo:


The Roxul Comfortboard IS (3") looks fine to me, provided it doesn't have the aluminum vapor barrier or black coating stuck to one side.
Higher numbers are more absorption, with anything around 1.00 += 0.15 being as good as it gets.
The "250hz 0.82" is a tiny bit low but not much, but the "125hz 0.75" is nicer than the OC 703.
In another sense, the Roxul seems more evenly broadband which might be good, rather than the sharper dropoff in the 703 at 125hz.
The numbers are similar to RXL 60 / RXL 80 which I know is fine ( http://www.bobgolds.com/AbsorptionCoefficients.htm ).
A difference of 40% you probably won't be able to hear (i.e. 1.00 vs 0.60, not 0.01 vs 0.40 which you would hear and would be 4000%). A difference of 20% you probably won't be able to measure.


----------



## BasementBob

memmo said:


> since I need a bunch (and have a small hatchback) it would require multiple trips.


[humor]
http://www.nairaland.com/attachments/936918_overload2_jpgd9860df77c962c7986c1e73087d17dd1
http://transportfool.com/wp-content/uploads/2008/05/overloaded.jpg
http://www.swapmeetdave.com/Humor/Workshop/Overload.htm


----------



## memmo

Thanks for the insight 

Now I have to figure out how to make the best out of the side walls where I've only accommodated for 1" behind my fabric panels. As I've come to learn this is far from ideal and using any absorption may/may not make things even worse.

That being said, There are a dozen + builds in the same predicament and the owners are happy with the rooms... 

Any best practices I can try? How about some RPG BAD diffuser panel clones on the upper side walls with 1" of Linacoustic?


----------



## HopefulFred

memmo said:


> How about some RPG BAD diffuser panel clones on the upper side walls with 1" of Linacoustic?


I don't think I would go to the trouble of building a BAD panel unless I really wanted it at a specific reflection point. Away from early reflection points, you can't beat exposed drywall for maintaining sound energy (as far as I know), and diffusing it is of marginal utility, IMO.


----------



## memmo

HopefulFred said:


> I don't think I would go to the trouble of building a BAD panel unless I really wanted it at a specific reflection point. Away from early reflection points, you can't beat exposed drywall for maintaining sound energy (as far as I know), and diffusing it is of marginal utility, IMO.


Good to know. I suppose I'll just have to try a bunch of options. I have 2" of Linacoustic on the front wall (with 3mil poly in-between) and I'll have corner bass trapping behind the false wall. On the rear wall, I'm doing 3" of OC 705 with a 1" gap and will possibly entertain some more corner trapping if required.. its just the side walls that I'm limited to 1" -- so perhaps I should at very least do some 1" at the first reflection points and leave everything else exposed drywall and see what its like.

I do have a friend with a CNC, so the BAD panels would be free...


----------



## viperx116

Where can I buy some inexpensive 2" batts? The Home Depot near me has Roxul but only in 3". There's seems to be only one seller online for the Roxul 2" and it's super expensive (costs a ton for shipping).


----------



## ellisr63

viperx116 said:


> Where can I buy some inexpensive 2" batts? The Home Depot near me has Roxul but only in 3". There's seems to be only one seller online for the Roxul 2" and it's super expensive (costs a ton for shipping).


I went to Lowes and had them order them for me... 2" R80. They had it delivered to me 2 days later. Now the Roxul R60 3" took a month to get as it had to be ordered out of Canada.


----------



## rprice54

viperx116 said:


> Where can I buy some inexpensive 2" batts? The Home Depot near me has Roxul but only in 3". There's seems to be only one seller online for the Roxul 2" and it's super expensive (costs a ton for shipping).


I'm using 3" Roxul safe n sound which I can get locally. Very similar to 703 from what I read. Saves a bunch on shipping too.


----------



## rprice54

Ill be using it for wall panels as well


----------



## viperx116

ellisr63 said:


> I went to Lowes and had them order them for me... 2" R80. They had it delivered to me 2 days later. Now the Roxul R60 3" took a month to get as it had to be ordered out of Canada.


How much did it cost?

Edit: I'm seeing a R-8, but no R80. Is this the same?
http://www.roxul.com/products/residential/products/roxul+comfortboard+is


----------



## Marv Bagg

*Non Acoustic screen treatment*

Any one have a rough idea of what frequency would penetrate my Stewart Night Hawk non acoustic projector screen. I am considering some absorption in the 12 inch gap behind the screen but not sure if this makes any sense. Most high frequencies would be reflected but I'm wondering about what frequency range the screen would start to absorb?
Thanks guys.


----------



## Gooddoc

I have had no luck with EQ and I'd like to correct a FR issue with room treatments.

I'd like to correct the dips in the response in the 180 Hz to 800 Hz range


























How would I go about figuring out what treatments are necessary to correct that area of the FR? Or is it even possible to do that?


----------



## BasementBob

Gooddoc said:


> How would I go about figuring out what treatments are necessary to correct that area of the FR?


Relative to 10hz to 50hz, your 180 Hz to 800 Hz range should be much easier to deal with.

Start with the simple stuff:
1) See if you have any axial modes in the range. Consider putting absorption along that axis. http://www.bobgolds.com/Mode/RoomModes.htm
2) temporarily put a few 4"x2'x4' uncovered rigid fiberglass/rockwool panels vertically in all four corners, and on the floor under the screen and on the floor along the back wall of the room, Studiotips Corner Absorber style. And re-measure to see if it had an effect.
3) temporarily put 4"x2'x4' uncovered rigid fiberglass/rockwool panels at the first reflection points (side walls, front wall behind speakers, floor in front of primary listening position, and ceiling if you can). And re-measure to see if it had an effect.

(If you can't find 4", 3" is fine.)


----------



## ellisr63

viperx116 said:


> How much did it cost?
> 
> Edit: I'm seeing a R-8, but no R80. Is this the same?
> http://www.roxul.com/products/residential/products/roxul+comfortboard+is


Mine are called Rockboard 60, and Rockboard 80 on labels. I think they were around $60 per bundle. I got a deal on the R60 at $44 a bundle as it arrived damaged so we negotiated the price.


----------



## Gooddoc

BasementBob said:


> Relative to 10hz to 50hz, your 180 Hz to 800 Hz range should be much easier to deal with.
> 
> Start with the simple stuff:
> 1) See if you have any axial modes in the range. Consider putting absorption along that axis. http://www.bobgolds.com/Mode/RoomModes.htm
> 2) temporarily put a few 4"x2'x4' uncovered rigid fiberglass/rockwool panels vertically in all four corners, and on the floor under the screen and on the floor along the back wall of the room, Studiotips Corner Absorber style. And re-measure to see if it had an effect.
> 3) temporarily put 4"x2'x4' uncovered rigid fiberglass/rockwool panels at the first reflection points (side walls, front wall behind speakers, floor in front of primary listening position, and ceiling if you can). And re-measure to see if it had an effect.
> 
> (If you can't find 4", 3" is fine.)


Thanks for the input. The calculator only went up to 180 Hz. but gave some great room information. Particularly that the Schroeder frequency is only about 100 Hz. It does give me a good idea where to start with treatments for the 50-70 Hz area









I have GIK 3.5" treatments at the 2nd reflection points and floor to ceiling GIK bass traps in all four corners. 1st reflection points are a challenge and I haven't bothered with them yet. There is some thought out there that suggests I might not even want to bother with them.









Still pretty much have no idea how to fix that 180 - 800 Hz area, any other suggestions with the additional information?

Thanks a whole lot!


----------



## BasementBob

Gooddoc:

Some more ideas for you to consider.

Apologies about the room mode calculator not working above 200hz. Actually that's probably a practical limit for modes anyway -- so I shouldn't have mentioned 'a room modes calculator' for 200-800hz it at all.. If you want to see the numbers higher anyway, you can go back to http://www.bobgolds.com/Mode/RoomModes.htm , push the SHOW OPTIONS button, and enter a hz value after "show frequencies less than". 




Gooddoc said:


> I have GIK 3.5" treatments at the 2nd reflection points and floor to ceiling GIK bass traps in all four corners. 1st reflection points are a challenge and I haven't bothered with them yet.


 
Cool that you already have absorbers.
Temporarily move all the 2nd reflection point absorbers to the 1st reflection point (in front of that door for example) and the floor wall locations (4 sides) and see what happens. If you don't have enough or they are rather permanently mounted, make a trip to home depot for some rigid rockwool panels. You will take these out of the bags.


If you have a front/back axial mode and you haven't seen your spouse raise an eyebrow lately, get 14 bags of fluffy fiberglass pink insulation, do not take them out of the bags, then stack them 7 wide and 8' tall across the back wall, and then give the room a listen. 




Gooddoc said:


> There is some thought out there that suggests I might not even want to bother with them.


Yes, there is a school of thought that says that there's a richness of sound field gain from first reflection point (indeed bipolar speakers go out of their way at this), and another school of thought that says that first reflections should be dropped by 12 to 20dB at all frequencies. Too little reflected energy and the room is cold and dead, too much and the room echoes, has strong directional impressions, false stereo imaging, poor sound clarity, and a narrow soundstage.


Be curious. Experiment with the Simple. See if you like the sound, both by ear and by measurement. Language clarity (anything in a language you barely speak, my mother being fluent in english her entire life would suggest anything from the United Kingdom would foot the bill), imaging (Star Wars Pod Race, Mission To Mars rotation scene, etc). Presumably there's something you have been listening to that you are confident isn't sounding right -- use that too.


Alternatively, you could try diagnosis, followed by treatment. [This will go faster if you get the feedback of someone who can do this for you (or hire someone competent, probably with a degree in Acoustics, but at least does it routinely possibly with an AVS customer appreciation).]
- verify background noise
- initial speaker placement (L/R 3 feet from walls, etc)
- check speaker and cable integrity, check speaker time delay, and sound level balance
- test each speaker individually for reflections, and ensure the high frequency reflections are 12dB quieter than direct sound. Measure the ITDG (all peaks within 25-30mSec should be 12dB below the direct sound level)
- deal with room modes via subwoofer positioning and a RTA.
- set the subwoofer crossover frequency for a room reason rather than a speaker reason.
- verify a lack of vibration via a slow sweep 11hz to 400hz.


(Do you have a multi-channel digital equalizer? I don't have one, but I hear they're the cat's meow. Just a thought.)


----------



## myfipie

> I have GIK 3.5" treatments at the 2nd reflection points and floor to ceiling GIK bass traps in all four corners. 1st reflection points are a challenge and I haven't bothered with them yet. There is some thought out there that suggests I might not even want to bother with them.


If at all possible I would relocate the panels you have on the side walls to the first reflection points just to hear how it sounds.


----------



## myfipie

> I have GIK 3.5" treatments at the 2nd reflection points and floor to ceiling GIK bass traps in all four corners. 1st reflection points are a challenge and I haven't bothered with them yet. There is some thought out there that suggests I might not even want to bother with them.


If at all possible I would relocate the panels you have on the side walls to the first reflection points just to hear how it sounds.


----------



## SherazNJ

Hi guys,
I have been exploring acoustic room treatments and the more I explore for my options, the more I get confused. So I have been looking into adding diffusers. Seems like there are many types and many companies selling them. But the prices are sky high. Installing 6 diffusers (3 on each side of wall and 2 on rear) seems like a project of like +2,500.00. I can't help to wonder if these are just good plain woods stacked with some space varying in depth (in terms of diffuser that has horizontal lines) or there is something very special about them that make them this expensive? 

So far found a few types of Diffusers. 
1 - With equal spacing lines varying in depth (2D).
2 - With cubes varying depth.

What is so special about them that make them this pricy?????
Thx


----------



## myfipie

> What is so special about them that make them this pricy?????


Mostly because they are made in lower quantities and very labor intensive. 

Just stacking wood is not going to diffuse sound. See the following to get a better understanding of how diffusion works.
http://www.gikacoustics.com/video-how-diffusion-works/
http://www.gikacoustics.com/diffusion-by-jeff-hedback/


----------



## Romans828

myfipie said:


> Mostly because they are make in lower quantities and very labor intensive.
> 
> Just stacking wood is not going to diffuse sound. See the following to get a better understanding of how diffusion works.
> http://www.gikacoustics.com/video-how-diffusion-works/
> http://www.gikacoustics.com/diffusion-by-jeff-hedback/


Has anyone tried to DIY something similar to the Quest PerfSorber (absorption/diffusion combo)? I know that Dennis Erskine uses these but hear that they are crazy expensive. I'm *sure *that I'm oversimplifying...but it looks like OC 703 and "some other material drilled out" could be used to do this. Thoughts?


----------



## grendelrt

Still in the process of setting up my dedicated theater space and have started to try and measure out spots for acoustical treatments. I have multiple spots and just wanted some advice on what sizes to use and how many spots? The screen wall is going to be blacked out with velvet, which from what I have read here (and breath tested) is too thick to add any sound absorbing material to, so I am left with the rest of the room. My plan is to make a few theater poster style treatments and then to use a solid color or pattern for some other treatments around the room. The room has two cutouts in it as well in the back where windows are, so I am not sure how to handle those. Any help would be appreciated, thanks!

Front right wall (Front speaker is around 40" tall)









Front left wall









Back center wall and back cutouts (second row of seating will eventually block the bottom of this wall)









Back center wall gradient


----------



## HopefulFred

Romans828: the hybrid design you're thinking of exists. It was pioneered as a product known as a BAD panel (binary amplitude diffuser). The design is secret and protected as intellectual property, but you can find what appear to be competent knock-offs among DIYers around here and elsewhere. 

Grendlert: I'd start with as much absorption as I could fit in the front corners behind those L and R speakers. Others may have other priorities or additional recommendations.


----------



## Romans828

Thanks Fred.


----------



## grendelrt

HopefulFred said:


> Romans828: the hybrid design you're thinking of exists. It was pioneered as a product known as a BAD panel (binary amplitude diffuser). The design is secret and protected as intellectual property, but you can find what appear to be competent knock-offs among DIYers around here and elsewhere.
> 
> Grendlert: I'd start with as much absorption as I could fit in the front corners behind those L and R speakers. Others may have other priorities or additional recommendations.


Thanks!


----------



## myfipie

> Grendlert: I'd start with as much absorption as I could fit in the front corners behind those L and R speakers. Others may have other priorities or additional recommendations.


Plus one.. Also see the following videos and articles to give you a hand.
http://www.gikacoustics.com/educational-videos/
http://www.gikacoustics.com/articles/


----------



## grendelrt

Thanks Glenn, I will try to mark out all the early reflection points tonight based on what I just read there as a starting point. For my panels, from what I am reading 2" thick material should be enough for these panels, should I do a 4" frame border to allow 2" air gap ? ( EDIT : Just read in the primer you linked I should probably take advantage of the air gap) I will probably try to put some bass traps in the back corner eventually as well. I am reading as much as I can, but I get conflicting information depending on source and usage (not everyone is using panels for the same thing).


----------



## myfipie

If at all possible I would use 4" panels with a few inches of a air gap, but if you can't 2" will work. Small rooms need as much low end control as possible and 4" with a gap will start to be effective around 100hz.


----------



## crimsonblue

Hi all, my theater and equipment have been built for a while, but I'm just now getting around to the acoustics. 

Everyone seems to be pushing big foam fabric-wrapped panels. Half say that is the best solution and the other half says that egg crate is just fine for sound dampening. My room is 12' wide by 30' long.

I've seen Aurelex everywhere, but I also found this company that does a lot with foam and appears very similar. Would a bunch of these in the appropriate reflection points do the job? The prices seemed pretty reasonable. Thanks in advance for your guidance!


----------



## HopefulFred

A bunch of those at reflection points will take all the sparkle out of your system and mitigate some flutter echo that you may or may not have. I bet that's not what you want. 

Foam is not usually well suited to solving the problems people often have, like modal control and dialog intelligibility. Fiberglass and other thicker fibrous materials are usually much more effective for those tasks. 

If you can describe what problems you have and maybe provide some measurements of you system, we can help you focus your attention and efforts on fruitful techniques and materials. An approximate scale drawing of your 
space, including speaker and seating locations, will be needed as well as speaker models.


----------



## BasementBob

HopefulFred said:


> Foam is not usually well suited to solving the problems people often have, like modal control and dialog intelligibility. Fiberglass and other thicker fibrous materials are usually much more effective for those tasks.


Wool (glasswool aka fiberglass, or rockwool) is usually cheaper than foam too.


----------



## crimsonblue

HopefulFred said:


> A bunch of those at reflection points will take all the sparkle out of your system and mitigate some flutter echo that you may or may not have. I bet that's not what you want.
> 
> Foam is not usually well suited to solving the problems people often have, like modal control and dialog intelligibility. Fiberglass and other thicker fibrous materials are usually much more effective for those tasks.
> 
> If you can describe what problems you have and maybe provide some measurements of you system, we can help you focus your attention and efforts on fruitful techniques and materials. An approximate scale drawing of your
> space, including speaker and seating locations, will be needed as well as speaker models.


Thank you so much -- the willingness of folks on these boards to help out astounds me! 

Attached are some of the pics and a rough diagram. I've run Audyssey (from a Denon AVR-4311CI) to calibrate my Infinity Beta 50 fronts and Beta C360 Center (6.5" woofers) and Beta ES250 Di/Bipoles. I get good sound, but the room space is narrow and I'm guessing there is more bounce in what I'm hearing than there should be. Two 12" subwoofers (one Infinity SW-12 and one Bic F-12) can be seen, and I wired two 8" JBL ceiling speakers in front of the main listening position for Atmos (right now those speakers a matrix-balanced with my front height speakers). 

Should I just go the Home Depot route and start building panels?


----------



## ellisr63

crimsonblue said:


> Thank you so much -- the willingness of folks on these boards to help out astounds me!
> 
> Attached are some of the pics and a rough diagram. I've run Audyssey (from a Denon AVR-4311CI) to calibrate my Infinity Beta 50 fronts and Beta C360 Center (6.5" woofers) and Beta ES250 Di/Bipoles. I get good sound, but the room space is narrow and I'm guessing there is more bounce in what I'm hearing than there should be. Two 12" subwoofers (one Infinity SW-12 and one Bic F-12) can be seen, and I wired two 8" JBL ceiling speakers in front of the main listening position for Atmos (right now those speakers a matrix-balanced with my front height speakers).
> 
> Should I just go the Home Depot route and start building panels?


Building panels is pretty easy, and inexpensive. I purchased Roxul R60 and R80 for my panels from Lowes (special order), and then just picked up the wood for framing them in. I also ordered GOM for the fronts and went to JoAnnes for some cheap Muslim material for the backings.


----------



## blazar

archiguy said:


> What's the best way to attach the Linacoustic to the back wall (painted drywall on 2x6's at 16" O.C.)...?


Perhaps green glue?


----------



## crimsonblue

Got it. Home Depot doesn't seem to have R80 in stock online or in stores so I'll see if they can special order, or drive further to Lowes. 

If I ever rip apart my walls again, should I put R60 in between the studs? It's a dedicated basement home theater and I can't figure out how having insulation_ behind _the wall would make much difference for reflections other than as a harder wall. Would this be the right order for sound deadening?

1. On-wall treatments and in-wall treatments
2. On-wall treatments
3. In-wall treatments

In addition, I'm not entirely clear on the benefits of R40 v. R60 v. R80 for bass management. Some people say R40 and some say R80.


----------



## HopefulFred

You're right to be concerned about the usefulness of insulation within the wall/ceiling. It would contribute to keeping the room quiet, which is important for having a good sounding space, but it won't change the behavior of sound within your room. This is the difference between the thread (acoustic treatments) and another thread in this forum - the soundproofing master thread. 

There are differences between the products, but the differences among them are much smaller than the differences in implementation. So let's deal first with what goals we might have for improving your space, and then determine what characteristics to look for in products. 

The hardest to fix with treatments will be bass, so here's my recommendation without seeing exact details of placement and performance. Make sure the subs are in different portions of the room. Add absorptive treatments to any corners that you can (though it looks like that will be tough in your space). Then make sure they are properly set up for delay and phase at the main listening position. Last, apply some mild EQ to flatten the response at the main listening position. 

The left and right mains are pushed into corners by the large screen. I'd need to see anechoic measurements of those speakers to be sure, but I bet they are designe to sit out farther from the walls (probably three feet or more). When that's the case, the nearby walls will reinforce the low-end sensitivity and you end up with an overpowering bass response. EQ may be necessary, but you should also try some thick absorption on the side walls next to the speakers to mitigate the boost. 

In the rear half of the room, near the seating, I'm less certain. The diffuse character you get from your surrounds is probably a good choice given the proximity to the seating, but there is probably still some troubling flutter echo between the side walls. A few simple panels to the sides of the seating is probably adequate. 

For the corner bass treatments, you want as much material and space as you can sacrifice. If you can get to thicknesses around a foot, you should focus on a low density product, like common batts of insulation. But if you will be limited to less, I'd recommend a rigid rock wool panel about 6 pounds per cubic foot.

For the panels near the mains, I'd recommend the same 6 pound product at four inches thick or six inches if you can manage it. 

On the side walls b the seating, a 2" panel of the same is probably a reasonable compromise, given the space constraints. Thicker would be better. 

This should be a good start. There are other worthwhile approaches, but this is where I would start. Remember to run you auto calibration after any of these changes.


----------



## crimsonblue

HopefulFred said:


> This should be a good start. There are other worthwhile approaches, but this is where I would start. Remember to run you auto calibration after any of these changes.


Thank you so very much!! I can't tell you how helpful this is!!


----------



## ellisr63

crimsonblue said:


> Got it. Home Depot doesn't seem to have R80 in stock online or in stores so I'll see if they can special order, or drive further to Lowes.
> 
> If I ever rip apart my walls again, should I put R60 in between the studs? It's a dedicated basement home theater and I can't figure out how having insulation_ behind _the wall would make much difference for reflections other than as a harder wall. Would this be the right order for sound deadening?
> 
> 1. On-wall treatments and in-wall treatments
> 2. On-wall treatments
> 3. In-wall treatments
> 
> In addition, I'm not entirely clear on the benefits of R40 v. R60 v. R80 for bass management. Some people say R40 and some say R80.


I am not sure either... I was told to use R60 for the bass traps as it was better for bass traps, and to go at least 8" thick so we went 9" thick (3 layers of 3"). Our first reflection points are all 4" thick (2 layers of 2")... Originally we were just going to go 2" thick, but I was told to go 4" so I ordered more.


----------



## coolgeek

HopefulFred said:


> You're right to be concerned about the usefulness of insulation within the wall/ceiling. It would contribute to keeping the room quiet, which is important for having a good sounding space, but it won't change the behavior of sound within your room. This is the difference between the thread (acoustic treatments) and another thread in this forum - the soundproofing master thread.
> 
> There are differences between the products, but the differences among them are much smaller than the differences in implementation. So let's deal first with what goals we might have for improving your space, and then determine what characteristics to look for in products.
> 
> The hardest to fix with treatments will be bass, so here's my recommendation without seeing exact details of placement and performance. Make sure the subs are in different portions of the room. Add absorptive treatments to any corners that you can (though it looks like that will be tough in your space). Then make sure they are properly set up for delay and phase at the main listening position. Last, apply some mild EQ to flatten the response at the main listening position.
> 
> The left and right mains are pushed into corners by the large screen. I'd need to see anechoic measurements of those speakers to be sure, but I bet they are designe to sit out farther from the walls (probably three feet or more). When that's the case, the nearby walls will reinforce the low-end sensitivity and you end up with an overpowering bass response. EQ may be necessary, but you should also try some thick absorption on the side walls next to the speakers to mitigate the boost.
> 
> In the rear half of the room, near the seating, I'm less certain. The diffuse character you get from your surrounds is probably a good choice given the proximity to the seating, but there is probably still some troubling flutter echo between the side walls. A few simple panels to the sides of the seating is probably adequate.
> 
> For the corner bass treatments, you want as much material and space as you can sacrifice. If you can get to thicknesses around a foot, you should focus on a low density product, like common batts of insulation. But if you will be limited to less, I'd recommend a rigid rock wool panel about 6 pounds per cubic foot.
> 
> For the panels near the mains, I'd recommend the same 6 pound product at four inches thick or six inches if you can manage it.
> 
> On the side walls b the seating, a 2" panel of the same is probably a reasonable compromise, given the space constraints. Thicker would be better.
> 
> This should be a good start. There are other worthwhile approaches, but this is where I would start. Remember to run you auto calibration after any of these changes.



I too have very limited space for proper bass traps. Would a 3 feet thick rockwool at the whole frontstage top v wall (triangle) trap work? Or, is it too thick? I am using rockwool 80kg/cubic meter. It's a huge bass trap that spans the entire left to right, top of the wall... it extends down 3.5 feet and out 3.5 feet and triangular in shape.


----------



## myfipie

ellisr63 said:


> I am not sure either... I was told to use R60 for the bass traps as it was better for bass traps, and to go at least 8" thick so we went 9" thick (3 layers of 3"). Our first reflection points are all 4" thick (2 layers of 2")... Originally we were just going to go 2" thick, but I was told to go 4" so I ordered more.


When ever possible, thicker is better.


----------



## dm_rep

Could someone tell me what to look for when comparing Linacoustic rc to other products? Is it the NRC number or is there more to look for? Is higher the NRC better?


----------



## HopefulFred

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## dm_rep

HopefulFred said:


> http://www.bobgolds.com/AbsorptionCoefficients.htm


Do I compare the NRC number or all of it?


----------



## HopefulFred

Bob has organized the absorption coefficients for each material. The higher the coefficient, the greater the absorption. Presumably, if you're installing an absorber, you want the most absorptoon. But you should be thinking about the frequency ranges you need most absorption in.


----------



## myfipie

HopefulFred said:


> Bob has organized the absorption coefficients for each material. The higher the coefficient, the greater the absorption. Presumably, if you're installing an absorber, you want the most absorptoon. But you should be thinking about the frequency ranges you need most absorption in.


Right and just to add you want to focus on how low in frequency the product works. If you put something that only absorbs upper frequencies you run risk of the room becoming unbalanced. Meaning low end is still bouncing around but upper frequencies are dead. Makes low end sound muddy/unclear.


----------



## blipszyc

HopefulFred said:


> In the rear half of the room, near the seating, I'm less certain. The diffuse character you get from your surrounds is probably a good choice given the proximity to the seating, but there is probably still some troubling flutter echo between the side walls. A few simple panels to the sides of the seating is probably adequate.


Not my room, but out of curiosity, do you reccomend these side panels near the seating position to be floor-to-ceiling, or floor-to-just above ear height?


----------



## HopefulFred

In that case, I was recommending them only to avoid flutter echo. For that purpose, I think very little coverage would be required. Naturally, the panle size could easily be expanded if the overall reverb characteristics of the room would benefit.


----------



## coli

Been doing some research on bass traps, but it doesn't seem that mineral wool/fiberglass bass traps are safe? Eg: http://www.ncbi.nlm.nih.gov/pubmed/8920752


----------



## smuggymba

Guys - I need to work on my media room acoustic panels next. The ceiling will be black and walls will be dark gray / Slate.

Instead of getting black acoustic panels, I'm thinking of getting Black & White canvas acoustic panels of skylines of different cities. Do you guys know where I could buy these. 

I did see www.gikacoustics.comand acousticalsolutions.com website and they do make art panels but not sure how we can select pics we want. Has anyone tried before? Do I need to buy high resolution pics off the internet first?

Thx for all the help!!

edit: looks like GIK does allow you to buy from a few websites. Has anyone tried this?


----------



## BllDo

coli said:


> Been doing some research on bass traps, but it doesn't seem that mineral wool/fiberglass bass traps are safe? Eg: http://www.ncbi.nlm.nih.gov/pubmed/8920752


First, that's a two decade old paper about specific ceiling tiles in Germany that had an issue with quality control in the manufacturing process. It's hardly comparable to insulation used in sound control applications. 
Second, most people wrap their sound treatments in some sort of fabric be it GOM, speaker cloth or even burlap. Even with the limitations of the latter, the fabric will act to contain any fibers that may become airborne for whatever reason.


----------



## BllDo

smuggymba said:


> Guys - I need to work on my media room acoustic panels next. The ceiling will be black and walls will be dark gray / Slate.
> 
> Instead of getting black acoustic panels, I'm thinking of getting Black & White canvas acoustic panels of skylines of different cities. Do you guys know where I could buy these.
> 
> I did see www.gikacoustics.comand acousticalsolutions.com website and they do make art panels but not sure how we can select pics we want. Has anyone tried before? Do I need to buy high resolution pics off the internet first?
> 
> Thx for all the help!!
> 
> edit: looks like GIK does allow you to buy from a few websites. Has anyone tried this?


Try this tread

http://www.avsforum.com/forum/19-de...inted-movie-poster-acoustic-panels-cheap.html


----------



## Skylinestar

My local dealer is selling this bass trap from Vicoustic :
http://www.vicoustic.com/hifi-home-cinema/products/acoustic-treatment/basstrap/panel/451

What's "alpha with Shape Indicators" rating?

Do you think a typical OC703 will be better or worse?


----------



## ellisr63

Skylinestar said:


> My local dealer is selling this bass trap from Vicoustic :
> http://www.vicoustic.com/hifi-home-cinema/products/acoustic-treatment/basstrap/panel/451
> 
> What's "alpha with Shape Indicators" rating?
> 
> Do you think a typical OC703 will be better or worse?


I would think OC703 would be better... I am not a fan of foam as I have heard it doesn't work well for Bass Traps.


----------



## Skylinestar

ellisr63 said:


> I would think OC703 would be better... I am not a fan of foam as I have heard it doesn't work well for Bass Traps.


But the graph rating looks nice on the 150-400Hz region....but how accurate/useful is this data?


----------



## BasementBob

ellisr63 said:


> I would think OC703 would be better... I am not a fan of foam as I have heard it doesn't work well for Bass Traps.


There's nothing wrong with foam from an absorption per cubic foot point of view, even for bass traps.
The problem with foam is:
- foam is usually more expensive than DIY via fiberglass/rockwool
- foam traps are often much smaller volume (not as deep), so they are less effective at lower frequencies.

In the below, the Studiotips Corner Absorbers and Superchunks are OC703, and the MegaLenrds are foam
MegaLenrds are 2’ along each wall (610 mm), compared to Vicoasustic Super Bass 90 which are 300mm, so the MegaLenrds are about 3 times the volume.









http://forum.studiotips.com/viewtopic.php?f=8&t=536


----------



## JW1028

*first and second reflection treatments*

Just wanted to jump in and post a quick question regarding side wall 1st and 2nd reflection points. I plan on using 4" unfaced OC703 with a 4" gap behind. If i'm using the 'mirror' method, and the front of the panel will be 8" out from the wall, does that mean that i need to place the mirror at an 8" offset from the wall as well to find the points? 
Thanks
Jeff


----------



## HopefulFred

I say no, Jeff. However, the panel will hopefully be wide enough that it doesn't matter.


----------



## rabident

I saw this concept picture a while back. Is it implied that the walls are fabric, with tons of acoustic treatments behind them?

How much surface area of the room normally needs to be covered by something?


----------



## coolgeek

rabident said:


> I saw this concept picture a while back. Is it implied that the walls are fabric, with tons of acoustic treatments behind them?
> 
> How much surface area of the room normally needs to be covered by something?


The fabric is usually covering some sort of acoustic treatment. What kind is the million dollar question, and may require some expert help who can calculate how your speakers behave in what kind of room.

As a rule of thumb, after experiencing dozens of HT room, I found that less absorbers and more diffusers makes for a more lively and natural sound. About 90% of the HT rooms I have been to seems to be overly treated, ie, with absorbers and even with very capable speakers, they sound 'dead'. 

One way to do it is to ensure the 'fabric' portions can be opened up easily so that you can replace whatever treatment you placed there should you find the need. All my fabric portions are made with either a panel with magnets or for bigger panels, made with hingers like wardrobe hinges, so i can always change whatever treatment i have behind them.


----------



## BasementBob

rabident said:


> How much surface area of the room normally needs to be covered by something?


It depends on the shape of the room, and what else is already in it.

Some people learn by rules, some learn by examples. I learn by examples. As such this book "How to build a small budget recording studio from scratch with 12 tested designs (3rd edition)" by Alton Everest and Mike Shea, (2002) was quite helpful to me. Seeing how they mixed the products together to achieve the results, eventually sunk in as a method. The first design is initially a bit confusing, but by the time they've done the 12th variation on the theme using the same techniques you can do it blindfolded, and the first design becomes obvious. Its not the whole puzzle, but its an answer to what you asked.


----------



## JW1028

JW1028 said:


> Just wanted to jump in and post a quick question regarding side wall 1st and 2nd reflection points. I plan on using 4" unfaced OC703 with a 4" gap behind. If i'm using the 'mirror' method, and the front of the panel will be 8" out from the wall, does that mean that i need to place the mirror at an 8" offset from the wall as well to find the points?
> Thanks
> Jeff


I was planning on 2' x 4' for each panel... This is my first plunge into setting up a room and after a huge amount of reading (and advice from the community), it seems to be a fairly standard size that is used. I'm assuming its because that is a standard size of the OC 703 panels. If you think they should be bigger, please let me know. I'm not to the building stage just yet. 
Thanks
Jeff


----------



## sm4llz

Hi,

I'd like to do some acoustic treatments and was hoping for suggestions. We turned our basement into a media room with a 136" 2.35 screen using a ceiling mounted JVC X500r projector. The rest of the setup is:

FL/FR - Definitive Mythos ST
L Sub/ R Sub - SVS PB-2000
SL/SR - Definitive UIW-RSS II Ceiling Mounted
SBL/SBR - Definitive Mythos GEM XL Ceiling Mounted

As you can see, I only have 1 side wall because the opposite side has a wetbar and opens to the hallway. We have 2 windows on the opposite side of the screen with black out curtains. 

Would there still be a benefit to putting treatments on the left side of the room and ceiling?

thanks!


----------



## mrevo2u

A lot has changed in the 10 years since this thread was started and I was wondering if someone can give me a brief update about current practices for treating front/side/rear walls. At least as a starting point until I fine tune with REW.


----------



## nitro28

I am starting to plan my acoustical treatments and had a question about super chunk bass traps. My theater is 14x22 and I was planning on putting floor to ceiling corner traps in the front at the very least. How big a difference does it make between using a 34" wide OC703 triangle vs cutting those in half and using a 24" wide triangle? If I did 24" triangles I could probably afford to do all for corners of the room. What do you think. Two in the front that are 34" or 4 that are 24"? 

I have two 18" subs. One in the front and one in the rear. Thanks.


----------



## myfipie

mrevo2u said:


> A lot has changed in the 10 years since this thread was started and I was wondering if someone can give me a brief update about current practices for treating front/side/rear walls. At least as a starting point until I fine tune with REW.


Not a lot has changed in the last 10 years but see some of the following to bring you up to speed.
http://www.gikacoustics.com/articles/
http://www.gikacoustics.com/educational-videos/


----------



## myfipie

nitro28 said:


> I am starting to plan my acoustical treatments and had a question about super chunk bass traps. My theater is 14x22 and I was planning on putting floor to ceiling corner traps in the front at the very least. How big a difference does it make between using a 34" wide OC703 triangle vs cutting those in half and using a 24" wide triangle? If I did 24" triangles I could probably afford to do all for corners of the room. What do you think. Two in the front that are 34" or 4 that are 24"?
> 
> I have two 18" subs. One in the front and one in the rear. Thanks.


More coverage of linear corner area will trump larger traps covering less. There are minimums I recommend (4" panel 2' wide straddling a corner) but 24" wide filling the corner will do a wonderful job and if you can cover a lot of corner area it will sound much better.


----------



## nitro28

myfipie said:


> More coverage of linear corner area will trump larger traps covering less. There are minimums I recommend (4" panel 2' wide straddling a corner) but 24" wide filling the corner will do a wonderful job and if you can cover a lot of corner area it will sound much better.


Thanks. What insulation would you recommend for the super chuncks? 703, Roxul, one of the Knauf products??


----------



## mrevo2u

myfipie said:


> Not a lot has changed in the last 10 years but see some of the following to bring you up to speed.
> http://www.gikacoustics.com/articles/
> http://www.gikacoustics.com/educational-videos/


10 years ago, DE was recommending 1" of insulshield on entire front wall and 1" OC 703 type on side/rear walls from ear height down. These days, I see recommendations of 1" insulshield/plastic sheeting/1" insulshield on front walls, 2" oc703 on rear walls and side walls treated at first reflection points. Am I way off based as a starting point?


----------



## ellisr63

We went with 3" of Roxul R60 on the entire front wall, 4" of Roxul R80 for the first reflection points on the side walls and ceiling, and 9" of Roxul R60 on the rear wall (just need to do the corner traps). It has made a tremendous improvement in the articulation of sound in our HT.


----------



## mrevo2u

ellisr63 said:


> We went with 3" of Roxul R60 on the entire front wall, 4" of Roxul R80 for the first reflection points on the side walls and ceiling, and 9" of Roxul R60 on the rear wall (just need to do the corner traps). It has made a tremendous improvement in the articulation of sound in our HT.



No other treatments? Did you measure before/after?


----------



## ellisr63

mrevo2u said:


> No other treatments? Did you measure before/after?


We were setting up a ground up system with new DIY speakers so we only measured for crossovers, and delays. We knew we needed first reflection panels, and I contacted GIK, and was told what should work with my setup... We have been adding panels slowly since July (running Audyssey after each mod), and I am very happy with the results. Hopefully we will have all the panels (acoustic, and decorator) done this week. My room is right on the border of having too much absorption so we need to be careful with the corner traps. One thing we did do was the rear wall has rubber sheeting covering the whole rear wall, and then GOM. We did this to try and not over dampen the room, and will do the same on the corner traps. Currently we have 7 bundles of Roxul R60 in the room that we have not unwrapped yet. I am hoping that when we do it doesn't over dampen the room. If it does we will tackle that at that time (I am assuming we could put diffusers behind the GOM if needed.


----------



## SherazNJ

ellisr63 said:


> We were setting up a ground up system with new DIY speakers so we only measured for crossovers, and delays. We knew we needed first reflection panels, and I contacted GIK, and was told what should work with my setup... We have been adding panels slowly since July (running Audyssey after each mod), and I am very happy with the results. Hopefully we will have all the panels (acoustic, and decorator) done this week. My room is right on the border of having too much absorption so we need to be careful with the corner traps. One thing we did do was the rear wall has rubber sheeting covering the whole rear wall, and then GOM. We did this to try and not over dampen the room, and will do the same on the corner traps. Currently we have 7 bundles of Roxul R60 in the room that we have not unwrapped yet. I am hoping that when we do it doesn't over dampen the room. If it does we will tackle that at that time (I am assuming we could put diffusers behind the GOM if needed.


Can you post REW graphs of before/after changes to show how it changed your room?


----------



## SherazNJ

Hi guys,
I"m in the middle of treating my room. I covered first reflection points. I don't have any bass traps installed yet. My question is "What do bass traps achieve?". If installed absorbing panels (4" thick mineral wool acoustic panels) to reduce the early reflection. I took before/after readings of L/C/R speakers. After installation, L/R don't have any reflection above -20 below 5ms (Filtere IR Graph) but center still has many spikes going above. I have 3 panels installed on ceiling but they don't seem to have taken care of the reflection for center speakers. I wonder if its the panels????

As far as low frequency is concerned, I do have a little decay around 20-40 going above 450 ms. Based on my understand, to get rid of that low frequency issue, one has to install a lottttt of pink stuff and I don't have that much of space behind AT screen to accommodate that much of space. Above 40hz, I don't have any decay issue. 
Since I don't have any bass traps installed, What difference will they bring and how can I measure that difference?

Thanks.


----------



## ellisr63

SherazNJ said:


> Can you post REW graphs of before/after changes to show how it changed your room?


We only did the REW plots when we were doing the crossover setup... After that we only used Audyssey after each mod. If we had just made the acoustic mods it would make sense but since we moved the speakers, and mic positions with Audyssey I don't think REW measurements would mean anything anymore..


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## RH55

ellisr63 said:


> I believe that some people are using screws (long), and fender washers... I have also seen some screws and washers made specifically for it but I can't remember where.


I put 2" of linacoustic with 3 mil poly in between on my front wall two weeks ago. I tried screws but found that roofing nails with the plastic caps worked perfectly. I got them at Home Depot in the hardware aisle.


----------



## ellisr63

RH55 said:


> I put 2" of linacoustic with 3 mil poly in between on my front wall two weeks ago. I tried screws but found that roofing nails with the plastic caps worked perfectly. I got them at Home Depot in the hardware aisle.


Good solution! We built a 2x4 frame on the wall and stuffed R60 in the openings and just wrapped the whole wall with black commando cloth.


----------



## RH55

Nice, that works if you've got the room. I agonized for months over what to use to hold everything together but I forget that the details just disappear when the lights go down.


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## Vladimir Gapon

*acoustical treatment*

hi,
I have a confusion, I have room 25x18x10. need sound treatment done, my plan was co cover all walls and cealing with Roxul Rockboard 80, Mineral Wool Board, it has good sound absorbing. After reed some post, get confused. is is good or not to cover all walls, I thought it will be good for sound, please give me advise to get best sound out.
Thank you


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## BasementBob

Vladimir Gapon said:


> is is good or not to cover all walls, I thought it will be good for sound, please give me advise to get best sound out.


It is NOT good to cover all the walls. Makes the room sound dead and unnatural.


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## Vladimir Gapon

How to calculate what percentage need to cover 50% -75%, and what to use 1 inch 2 inch 4 inch, some one told me 4 inch very good for bass, and again no body cant give clear answer, hope to get answer here. thank you


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## sdurani

Vladimir Gapon said:


> How to calculate what percentage need to cover 50% -75%, and what to use 1 inch 2 inch 4 inch, some one told me 4 inch very good for bass, and again no body cant give clear answer, hope to get answer here.


I would consider direction more than percentage. For example: covering the front wall with broadband absorption will keep reflections coming from the same direction as the L/C/R speakers from muddying up the soundstage. I would also cover the middle half of the back wall with absorption. Whether you want to absorb early side wall reflections or not comes down to personal preference. In the surround field, breaking up early reflections with diffusors will give you more envelopment than using absorbers. Rather than thinking about percentage, think about why you're placing treatment at a certain location.


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## Mashie Saldana

Can you do asymetric corner traps?

I have a square room 12x12x8 where front left and rear right corners have windows. I could do floor to ceiling super chunks on front right and rear left corner and up to the windows in the other two? 

Good/bad idea?


----------



## Vladimir Gapon

*egg crates as diffusers*



sdurani said:


> I would consider direction more than percentage. For example: covering the front wall with broadband absorption will keep reflections coming from the same direction as the L/C/R speakers from muddying up the soundstage. I would also cover the middle half of the back wall with absorption. Whether you want to absorb early side wall reflections or not comes down to personal preference. In the surround field, breaking up early reflections with diffusors will give you more envelopment than using absorbers. Rather than thinking about percentage, think about why you're placing treatment at a certain location.


 Thank you, I appreciate for any advises, what about egg crates use as diffusers? now I need change all design in my room to add diffusers maybe on ceiling and sides. Thanks


----------



## Laidback

Starting to build my front stage and just realized I wasn't sure where to put the corner bass traps...in front of or behind the screen wall. Screen will be AT.
Thanks!


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## granroth

Vladimir Gapon said:


> How to calculate what percentage need to cover 50% -75%, and what to use 1 inch 2 inch 4 inch, some one told me 4 inch very good for bass, and again no body cant give clear answer, hope to get answer here. thank you


I recommend watching the Acoustics 101 and Acoustics 102 videos from Home Theater Geeks 177 and 178 with Anthony Grimani. They are absolutely the best intro to acoustics I've heard and, notably, they cover things like coverage levels very clearly.

http://twit.tv/show/home-theater-geeks/177
http://twit.tv/show/home-theater-geeks/178

(also available on YouTube)


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## Brian Fineberg

i have two accoustical treatments from my old room (ats 24x24x2)









any advice how to attach them to a concrete wall? (which is currently covered by felt...)


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## Mashie Saldana

Brian Fineberg said:


> i have two accoustical treatments from my old room (ats 24x24x2)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> any advice how to attach them to a concrete wall? (which is currently covered by felt...)


I'm note sure how those look on the back but I assume a wooden frame at the top. Can't you just attach two angular brackets that are roughly 2" long to the wall and then hang the top wooden frame on top? If it is fabric on the back of the treatment just cut a small slot where the bracket have to come through.


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## AXLCMT

I'm planning on building Fabric Panels with 2 (two) rolls of Linacoustic (1" thick each) for the Ear Height to the floor,
and then Cotton Batting from Joanne's Fabrics for the Fabric Panels "Ear Height" to the ceiling.

What size furring strips should the Fabric Panels be?

Should the Fabric Panels be exactly 2" deep/thick or should I make them a little "deeper/thicker" because the Linacoustic
will "press against" the Fabric, hindering the "smooth" look of Fabric being stretched with the "illusion" of nothing behind the Fabric?

With 2" furring strips in this scenario, will the 2" of Linacoustic "press" against the Dazian Fabric I plan on covering the Fabric Panels with?

What is the actual thickness of 1" of Linacoustic after installation (ie how far out does it stick out of the wall after installation?

Should I make my Fabric Panel 'furring strips' a little deeper/thicker (say 2 1/4") to hold 2" of Linacoustic?

How about Joanne's Fabric's Cotton Batting? How many layers will "equal" the depth of 2" of Linacoustic (since I obviously want both of the "upper" and "lower"
Fabric Panels to be flush with each other)? How thick is Cotton Batting after installation?


----------



## Brian Fineberg

Mashie Saldana said:


> I'm note sure how those look on the back but I assume a wooden frame at the top. Can't you just attach two angular brackets that are roughly 2" long to the wall and then hang the top wooden frame on top? If it is fabric on the back of the treatment just cut a small slot where the bracket have to come through.


ok..how would you hang those brackets to the concrete wall?


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## Mashie Saldana

Brian Fineberg said:


> ok..how would you hang those brackets to the concrete wall?


Drill holes and then use two plugs and two screws for each.


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## mrnagrom

could acoustic treatments on my walls be used to calm some of the city noise in my house?


----------



## Mashie Saldana

mrnagrom said:


> could acoustic treatments on my walls be used to calm some of the city noise in my house?


Not really, you want green glue and another layer of plasterboard for that.


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## granroth

mrnagrom said:


> could acoustic treatments on my walls be used to calm some of the city noise in my house?


Well... that depends. Acoustic treatments aren't at all designed to reduce the noise level but rather selectively absorb target frequencies to prevent them from bouncing around. If you measure the decibel level in a room, then randomly install some treatments, and then re-measure the room, you'll find that there was little to no change in the sound level.

Reducing the sound level requires "soundproofing", a topic that is covered in this thread's sister thread: Soundproofing Master Thread

But... that doesn't mean that acoustic treatments wouldn't help at all. See, sound volume and "loudness" can be thought of as two separate things. The volume is the sound level as measured objectively using a decibel meter. The loudness is how loud that sound is perceived by you. There's absolutely a different between the two. Try watching a movie at 85 dB and then listen to a baby screaming at 85 dB. I guarantee you'll rate the baby screaming as much louder.

This is where the acoustic treatments can come in. By reducing the echo and reverberation in the room, the sound feels less chaotic and "smoother". You might actually feel like it's not as loud, even though the volume is unchanged.

Really, acoustically controlling a room just makes the room a more pleasant place to be, regardless of volume. It could absolutely be worth your time to do it regardless.


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## Vladimir Gapon

granroth said:


> I recommend watching the Acoustics 101 and Acoustics 102 videos from Home Theater Geeks 177 and 178 with Anthony Grimani. They are absolutely the best intro to acoustics I've heard and, notably, they cover things like coverage levels very clearly.
> 
> http://twit.tv/show/home-theater-geeks/177
> http://twit.tv/show/home-theater-geeks/178
> 
> (also available on YouTube)


 Thank you, very interesting, very interesting setup diffuser-absorber- diffuser, reed a lot of post, everybody telling different, wish to hear that sound on Acoustic 101, did some one install with same plan?
Thank you


----------



## myfipie

Mashie Saldana said:


> Can you do asymetric corner traps?
> 
> I have a square room 12x12x8 where front left and rear right corners have windows. I could do floor to ceiling super chunks on front right and rear left corner and up to the windows in the other two?
> 
> Good/bad idea?


Symmetry is most important from where you sit forward. If you have windows in one of those corners then use something that can free standing and stacked. Something along these lines.
http://www.gikacoustics.com/product/gik-acoustics-soffit-bass-trap/


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## Mashie Saldana

myfipie said:


> Symmetry is most important from where you sit forward. If you have windows in one of those corners then use something that can free standing and stacked. Something along these lines.
> http://www.gikacoustics.com/product/gik-acoustics-soffit-bass-trap/


For symmetry the best I can do is 1m worth of soffit traps or super chunks in all four corners but that is only 40% of the wall height covered. No idea how much effect that would have on the sound. Due to WAF I can forget about having traps blocking the windows. Padded curtains made from say duvets are ok though but would that be remotely similar to the soffit traps?


----------



## Audixium

granroth said:


> I recommend watching the Acoustics 101 and Acoustics 102 videos from Home Theater Geeks 177 and 178 with . They are absolutely the best intro to acoustics I've heard and, notably, they cover things like coverage levels very clearly.
> 
> http://twit.tv/show/home-theater-geeks/177
> http://twit.tv/show/home-theater-geeks/178
> 
> (also available on YouTube)


Hadn't seen those before - thanks for sharing the links. Interesting absorb/diffuse pattern approach...


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## granroth

*Soffit as partial bass trap*

Let's say I'm building a soffit that wraps around my entire theater and mostly exists as a chase for HVAC ducts and wiring. In fact, the entirety of both sides and 3/4 of the back of the soffit are monopolized by the ductwork. That does leave a roughly 13' x 4' x 10" section of soffit above the stage that will have nothing practical in it.

So I'm thinking I can do double duty on that part and turn it into a bass trap by stuffing it with insulation. The question is "how"?

The soffit will be built with dual layers comprised of 5/8" OSB + 5/8" Drywall (since most of it is to hide possibly noise HVAC). I'm assuming that that will also effectively reduce the "bass trap" ability of the soffit to unmeasurable levels.

If that's true, then that implies that I will need a hole in my soffit? Maybe covered with fabric?

If so, then how big should said hole be, to be an effective bass trap?

Just pink fluffy stuffing, or would it really help to use rigid fiberglass?


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## myfipie

I would not use holes, but cover it with fabric, keeping it open on all sides facing the room. And yes use normal fluffy fiberglass.


----------



## granroth

myfipie said:


> I would not use holes, but cover it with fabric, keeping it open on all sides facing the room. And yes use normal fluffy fiberglass.


So this is roughly what it'll look like (minus the light tray):










The grey part is entirely taken up by ductwork (in fact, 3/4 of it _is_ the duct) so only the green part is available to be a bass trap.

Are you suggesting to essentially have _no_ bottom and _no_ side to the green part of the soffit (other than the frame) and to install just have fabric covering the frame and fiberglass?


----------



## artur9

Any suggestions for how to treat a 31.5Hz room mode? It shows in my REW measurements as a null (i.e. not a hump). It's very narrow so it's not a cause for major concern.

I played with the PEQ on my Dayton SA1000 equivalent but boosting did nothing but make other frequencies worse. Cutting didn't seem to have any effect whatsoever.


----------



## HopefulFred

31.5 Hz will most likely be a first order length mode resonance in most rooms. Your whole room rings like a tuning fork at that frequency, so there is a LOT of energy built up in that resonance. Absorbing the energy with a velocity based absorber will prove disappointing, I'm afraid.

You are probably best served by first relocating your sub(s) or adding a second. If you can't make that work, for whatever reason, I'd say you need to be looking into a resonant trap solution.


----------



## blazar

At 31.5 there is limited music content. You wont notice the null during playback I think.

In either case, multiple subs is most obvious way to help this problem with reasonable certainty.

Just moving one sub around will often just create different peaks and nulls. Tuning options and permutations increase a lot with multiple subs.


----------



## artur9

HopefulFred said:


> 31.5 Hz will most likely be a first order length mode resonance in most rooms. Your whole room rings like a tuning fork at that frequency, so there is a LOT of energy built up in that resonance. Absorbing the energy with a velocity based absorber will prove disappointing, I'm afraid.
> 
> You are probably best served by first relocating your sub(s) or adding a second. If you can't make that work, for whatever reason, I'd say you need to be looking into a resonant trap solution.


Well, I have 4 subs and I've located them in all kinds of places. I believe for that mode the only placement that addresses the problem is dead center in the room. 

I've attached the REW measure just for the subs. It's unsmoothed and without any EQ (I don't have access to any). Looking at it in conjunction with the L main it doesn't look so bad.

According to a calculator I googled I'd need a 9ft gap behind an absorber!  Seems a bit much. 

Does a tube trap count as a resonant trap? Or are they something else? Is there a DIY I can follow to see if I can make a dent in it?


----------



## HopefulFred

A tube trap is the sort of trap that might help, but they are tough to build and tune and you may need several.

Have you tried adjusting phase, polarity, or delay of some of your subs? I'd start by inverting the polarity of the subs in one half (either front or rear) of the room.


----------



## artur9

HopefulFred said:


> A tube trap is the sort of trap that might help, but they are tough to build and tune and you may need several.
> 
> Have you tried adjusting phase, polarity, or delay of some of your subs? I'd start by inverting the polarity of the subs in one half (either front or rear) of the room.


Yeah, I did that. Continuous phase, 0-180 switch level, whatever the sub supported. It was a lot worse before. I have no way to control delay at the moment. 

I do have a MiniDSP 2x4 that I've tried once or twice that never does what I expect/want. As a splitter it was awesome.


----------



## Laidback

Using Roxul for front and back walls. Wondering if it effects the absorption if it is painted. I'm not talking crazy slopped on painted, more of a light coating. If not covered in fabric what other options are you guys recommending to cover the Roxul in these areas?


----------



## Vladimir Gapon

Hi,
Can some one help me understand difference of absorbing panels and bass trap, is bass trap just should be thicker, if I have 4 inch panel with Roxul inside, can it be used for bass traps, or can it be use for absorbing panels.


Thank you for help


----------



## Jacob B

*Front wall?*



granroth said:


> I recommend watching the Acoustics 101 and Acoustics 102 videos from Home Theater Geeks 177 and 178 with Anthony Grimani. They are absolutely the best intro to acoustics I've heard and, notably, they cover things like coverage levels very clearly.
> 
> http://twit.tv/show/home-theater-geeks/177
> http://twit.tv/show/home-theater-geeks/178
> 
> (also available on YouTube)


In the Acoustics 101 video linked above, Anthony Grimani advice against treating the entire front wall.
He also advices against 
more than 20 % of absorption of the entire room surface.

This goes against the conclusions normally made in this thread - Would any of the experts here in the thread comment on that?

I am approaching the point in construction, where I treat the front wall and front corners. 
Plan was - before seeing the video - to treat:
- entire front wall with 2" Knauf RS60 (60 kg/m3), 
- soffit type corner traps 12"x20" Knauf ecobatt (fluffy) in front left and rigth corner, 
- soffit type 12"x12" Knauf ecobatt (fluffy) in ceiling/front wall corner)
See construction thread for details on other room surfaces.

Thanks,
Jacob


----------



## HopefulFred

@artur9 - I didn't mean to leave you hanging. You mentioned that the null wasn't a huge concern, and I probably agree on that, but I would interested in potentially pursuing the associated ringing that might be a concern. If you want to get into that, we'd need more data.


----------



## HopefulFred

Laidback said:


> If not covered in fabric what other options are you guys recommending to cover the Roxul in these areas?


For aesthetics? I have only seen fabric. In some cases, plastic sheeting might be used as part of the treatment, and that would visually cover the fibers - but I don't think that's going to be a reasonable aesthetic solution. I also don't think you're going to happy with it painted.


----------



## HopefulFred

Vladimir Gapon said:


> Hi,
> Can some one help me understand difference of absorbing panels and bass trap.
> 
> Thank you for help


Largely, this a matter of shades of gray. Ideally, your standard absorption panel should function to absorb bass, but they're generally too small to do that effectively. 4" gets close. 

The issue that probably drives most people's choice of term is actually placement. If the treatment is applied to a reflection point, it would normally be referred to as a treatment panel, whereas if it were placed in a corner the purpose is not managing specular reflections, but bass, so it would be called a bass trap.


----------



## HopefulFred

Jacob B said:


> In the Acoustics 101 video linked above, Anthony Grimani advice against treating the entire front wall.
> He also advices against
> more than 20 % of absorption of the entire room surface.
> 
> This goes against the conclusions normally made in this thread - Would any of the experts here in the thread comment on that?


I don't want to be called an expert, but I think you might be missing something. I'm not sure what you think is the normal conclusion, but I think its pretty close to what Mr Grimani is giving as a guideline. Imagine a room with six surfaces. Two will very seldom be treated (ceiling and floor). Those are often the largest surfaces - let's say they make 40% of the total surface. That leaves 60 units of surface available, and Grimani suggests you can treat up to 20 of them, or 1/3 of all the wall surfaces. If you were to treat the whole front wall (which is probably the smallest wall), that still leaves you leeway to treat for bass in rear corners or for a rear wall reflex, and maybe first reflections if you want to.

Fred.


----------



## Jacob B

HopefulFred said:


> I don't want to be called an expert, but I think you might be missing something. I'm not sure what you think is the normal conclusion, but I think its pretty close to what Mr Grimani is giving as a guideline. Imagine a room with six surfaces. Two will very seldom be treated (ceiling and floor). Those are often the largest surfaces - let's say they make 40% of the total surface. That leaves 60 units of surface available, and Grimani suggests you can treat up to 20 of them, or 1/3 of all the wall surfaces. If you were to treat the whole front wall (which is probably the smallest wall), that still leaves you leeway to treat for bass in rear corners or for a rear wall reflex, and maybe first reflections if you want to.
> 
> Fred.


I am aware of the 6 surface calculation. I have treated my ceiling as well with 5" fiberglass, see construction thread.

Now, if you go back 5-10 years, normal recommendation in this thread was treat entire front wall, and sidewalls from front wall and 2/3 back.
Some argued sidewalls only to earheight/4' up, others all the way up.

In addition, many HT builds, based on acoustic experts active at the time in this thread, also treated back wall, with 4-6" fiberglass. Sometimes only center of backwall, with diffusors on each side of the center, others treated the entire backwall.

The often quoted advice was "you can never have too much bass trapping in a small HT room" (I understand you need min 4-6" of fiberglasss before you can talk about absorbing bass). Diffusion was mentioned as "icing on the cake". Instead of 20 % absorption, around 50 % was what I heard.

*However, my strongest concern is Grimani's advice of NOT treating the entire front wall behind an AT screen.*

That is completely against what I have been reading here for the last 8 years.


----------



## artur9

HopefulFred said:


> @artur9 - I didn't mean to leave you hanging. You mentioned that the null wasn't a huge concern, and I probably agree on that, but I would interested in potentially pursuing the associated ringing that might be a concern. If you want to get into that, we'd need more data.


That's quite all right. I can measure the ringing in a few days time. What specifically would you like to see? Last time I measured I think it was


----------



## HopefulFred

Jacob B said:


> *However, my strongest concern is Grimani's advice of NOT treating the entire front wall behind an AT screen.*
> 
> That is completely against what I have been reading here for the last 8 years.


I won't argue with you there at all. If that's what he says (I haven't watched that since it was new), I couldn't explain why.


----------



## HopefulFred

artur9 - how about a diagram of the layout and subs, and what's in the signal chain?


----------



## granroth

Jacob B said:


> *However, my strongest concern is Grimani's advice of NOT treating the entire front wall behind an AT screen.*


He's been consistent about that in his (very frequent) writing as well. Here's an example:

http://www.residentialsystems.com/h...boiling-down-room-treatment-essentials/83652]

"Remember that the front wall is going to see mostly back wave from the speakers, which is low frequency. Thinner treatments do nothing in that range, so mid-bass absorbers are a good call for the front wall."

That follows from earlier when he says:

"By far the most common error in treating a room is to cover large portions of the surfaces with 1-inch absorptive material. This does nothing but suck out all the high frequency energy. It doesn’t address more serious acoustical concerns at mid and low frequencies. The room can actually sound worse than if you did nothing at all"

He does concede that there might be some benefit to front wall absorption:

"If you’re firing speakers through an acoustically transparent micro-perforated projection screen, absorb the front wall to catch slap-back off the screen."

This is echoed by Ethan Winer, here:

http://realtraps.com/art_front-wall.htm

"Most thin absorbers made of acoustic foam or rigid fiberglass are ineffective below about 500 Hz, yet this is precisely where absorption is needed most if the goal is to reduce or avoid reflections off the front wall. Treating the entire front wall won't solve this problem at low frequencies, nor is it needed or even useful at mid and high frequencies."

.
.
.

To sum up, the common thread between these articles is that the reasoning for front absorption is to stop reflections from the speakers... but 1" or 2" absorption mostly targets high frequencies, which are rarely a problem. It's the lower frequencies that radiate omni-directionally and the thin treatments don't help in that case. That is very interesting to me, since as you noticed, putting 1" or 2" of Linacoustic or similar on the front wall is almost standard practice around here. The comments by Grimani and Winer essentially seem to say that (other than with AT screens), that does nothing useful.


----------



## artur9

HopefulFred said:


> artur9 - how about a diagram of the layout and subs, and what's in the signal chain?


There's a diagram and equipment list in the My Setup link in my sig. It's not up to date. As you can see I've cobbled things together 

I have 2 subs flanking my bookshelf speakers to provide bass below their ability. 

I have another sub on the center left hand side. But the room is a strange shape so center doesn't mean much.

My 4th sub is on the center right hand side on a shelf about 5ft up. 

I try to use Geddes subwoofer optimization technique so that explains the flying sub 

Signal chain for the previously posted graph is 
Subwoofer off in the prepro to force bass to go to L/R.
L/R goes through Krell and signal is split to Gallo, Leon and Outlaw.

The reason for the split is so that the stereo subs work when only the Krell is on. Also, the more subs the more even the sound.

Crossovers for all tuned via REW and controls on the sub themselves. The Leon's amp is a rebranded SA1000.

Does that cover it?


----------



## Jacob B

granroth said:


> He's been consistent about that in his (very frequent) writing as well. Here's an example:
> 
> http://www.residentialsystems.com/h...boiling-down-room-treatment-essentials/83652]
> 
> "Remember that the front wall is going to see mostly back wave from the speakers, which is low frequency. Thinner treatments do nothing in that range, so mid-bass absorbers are a good call for the front wall."
> 
> That follows from earlier when he says:
> 
> "By far the most common error in treating a room is to cover large portions of the surfaces with 1-inch absorptive material. This does nothing but suck out all the high frequency energy. It doesn’t address more serious acoustical concerns at mid and low frequencies. The room can actually sound worse than if you did nothing at all"
> 
> He does concede that there might be some benefit to front wall absorption:
> 
> "If you’re firing speakers through an acoustically transparent micro-perforated projection screen, absorb the front wall to catch slap-back off the screen."
> 
> This is echoed by Ethan Winer, here:
> 
> http://realtraps.com/art_front-wall.htm
> 
> "Most thin absorbers made of acoustic foam or rigid fiberglass are ineffective below about 500 Hz, yet this is precisely where absorption is needed most if the goal is to reduce or avoid reflections off the front wall. Treating the entire front wall won't solve this problem at low frequencies, nor is it needed or even useful at mid and high frequencies."
> 
> .
> .
> .
> 
> To sum up, the common thread between these articles is that the reasoning for front absorption is to stop reflections from the speakers... but 1" or 2" absorption mostly targets high frequencies, which are rarely a problem. It's the lower frequencies that radiate omni-directionally and the thin treatments don't help in that case. That is very interesting to me, since as you noticed, putting 1" or 2" of Linacoustic or similar on the front wall is almost standard practice around here. The comments by Grimani and Winer essentially seem to say that (other than with AT screens), that does nothing useful.


Well, I AM using an AT screen and it is exactly for that reason I understood treating the entire wall was useful. 

However, I also understood that treating the front wall will negate reflections from the side and rear surrounds messing up the front soundstage.

*I believe treating any surface in the room with a thin absorber is done due to economic or space availability reasons. Any porous absorber should - for strictly acoustic reasons - be broadband, i.e. at least 4", or maybe min 2-3" with 1" space - as in your linked articles.*

That argument would lead to the conclusion that with an AT screen, treating the entire front wall should be with at least 4" porous absorber, in my case 60 kg/m3 Knauf RS60 rockwool batts.

Another option could be to place a 2'x4' four inch absorber behind each LCR speaker, rather than the entire wall. 
However, that does not fully address reflections from the backside of the AT screen, only backward bass radiation from the LCR speakers.
And what about the rear wall reflection of the LCR speakers, coming back to reflect off the front wall, and messing up the front soundstage? 
(I guess the latter can be addressed by treating the rear wall either with 4-6" absorption to _reduce_, or with diffusors in order to _delay_ the return of the LCR sound waves to the front wall - or a mix... BUT where does this rear wall talk leave the front wall treatment??)

*Would some of the acoustic experts care to comment on this?*


----------



## Laidback

I am in the same boat as Jacob B. I have 2" Roxul on front wall with AT screen. I want to know if I should add layer of pink n fluffy on top of that, remove the Roxul and go all pink or add another layer or 2 of Roxul? I figure I can make a decent little frame to hold back the fluffy with 1x4s and then staple fabric to it to help keep it in place. I am assuming that the pink n fluffy we are talking about is not paper backed.


----------



## HopefulFred

artur9 said:


> There's a diagram and equipment list in the My Setup link in my sig. It's not up to date.
> I have 2 subs flanking my bookshelf speakers to provide bass below their ability.
> 
> I have another sub on the center left hand side. But the room is a strange shape so center doesn't mean much.
> 
> My 4th sub is on the center right hand side on a shelf about 5ft up.
> 
> I try to use Geddes subwoofer optimization technique so that explains the flying sub
> Does that cover it?


Here's the attachment from the other thread.









Here's what I think you're describing as the new version.









If that's close, my initial concern is that all the subs are in the same quarter of the room, but I'm not certain that has to be a problem. It seems like you are pretty comfortable with REW and setting up your gear, so I imagine a solution can be found.

Can you identify where exactly you measured? And a bigger question is can you find other places with the same notch? (I suppose that you will either want to run REWs RTA with some pink noise or a sustained 31.5Hz tone (be careful with this to protect your subs) and walk around the room with the mic looking for the notch to appear.)

And still the biggest question is can you run everything through a low frequency sweep for a waterfall - get the levels up as high as you can handle so that we can see everything well above the noise floor.


----------



## artur9

HopefulFred said:


> Here's what I think you're describing as the new version.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> If that's close, my initial concern is that all the subs are in the same quarter of the room, but I'm not certain that has to be a problem. It seems like you are pretty comfortable with REW and setting up your gear, so I imagine a solution can be found.


That's very close. The TBI #2 is not there anymore. TBI #1 and #2 are your #1 and #2 . Your #3 is close to the end of that half wall, opposite end from where you have it. Then #4 is about 3-4ft to the left of where you show it, up in an alcove sort of thing (underneath is where the water pipes run). 

BTW, location #3 , on the sofa side of the half wall but at the end nearest the center of the room, gives the flattest subwoofer response of any that I've tried. Also, the TV is above TBI#2 in the diagram. Also, subs 1&2 are where they are because I low-pass them at 120Hz (to support the Haydn's) and I can localize subs starting around 90Hz at typical listening levels.


HopefulFred said:


> Can you identify where exactly you measured? And a bigger question is can you find other places with the same notch? (I suppose that you will either want to run REWs RTA with some pink noise or a sustained 31.5Hz tone (be careful with this to protect your subs) and walk around the room with the mic looking for the notch to appear.)


I see a lot of measuring this coming weekend. I measure from the end of the sofa next to the easy chair. My wife is less picky so she gets the easy chair but that's not the MLP 



HopefulFred said:


> And still the biggest question is can you run everything through a low frequency sweep for a waterfall - get the levels up as high as you can handle so that we can see everything well above the noise floor.


Sure. What frequencies would you like the sweep to cover? 15-200?


----------



## HopefulFred

15-200 is good. For comparison purposes, see this: http://www.hometheatershack.com/forums/rew-forum/36-please-read-getting-graphs-ready-post.html


----------



## eikon

I have a couple of acoustic questions to ask the experts. Greatly appreciate any input you folks might have. 


Due to some structural issues I'm planning to build in a way that would be slightly non-symmetrical. 

How important is it to have matching walls on right and left of a theater space? 
If one wall was about 12" further from the center of the room than the other wall, would that create bad acoustics?
If I did built-in bookcases into one wall and not the other, would that create bad acoustics? I'm assuming a bookshelf with media cases, books, decorations would act as a diffuser. So I would think I would need a diffuser on the other side or I'll have bad reflections right?

Here's my plan:









The screen is on the right side wall. The bottom wall (right side if you are looking toward the screen) offers more space than the left side. This is due to my need to keep my screen to the top side of the support poles. Anyhow, I have more space on that bottom wall and I was thinking I could use an extra 12" or so without making the room feel very "non-symmetrical". But I'm not sure what that extra foot on one side would do to acoustics. Also, I have an additional couple of feet of space between the bottom of that wall and the stairs. I was thinking I could do some built-in bookshelves along that wall since I have the extra space. BUT, I don't want to do these things if they will negatively affect acoustics. I'm not a pro.. I'm not experienced in professional sound spaces.. but I want to do the best I can with the space. 


Any thoughts here?

Thanks very much!!


----------



## hendry98

I have some questions regarding the acoustic treatment in my new HT (26' D, 15' W & 10' H) which will have AT screen with Triad LCR inwall Gold Speakers.

1- should i treat the front wall with 1", 2" or 4" 703 Fiberglass? note that i am planning to place GIK corner bass traps in the front wall.

2- i will place QRD diffusers, 2" absorption panels covered by GoM fabrics in the side walls in the areas that need to be treated (e.g., early reflection), but what do you suggest i should put inside the panels in other areas in the side walls where i dont plan to have any acoustic treatment? foam sponge, polyester batting .etc. to keep a uniform look and have no impact on the sound!

3- my sweet spot will be 10' away from the back wall, so should i place diffusers only? or mix of diffusers and absorption panels?

4- because of the space limitation i have in the front wall, can i place my two in-room Triad Gold Subwoofers in the front corners? if it is not a good idea, will EQ, Room treatment help to overcome the issues with this placement? or it is big no placement for dual subs!


Thanks in advance for any advice and help.


----------



## Jacob B

hendry98 said:


> I have some questions regarding the acoustic treatment in my new HT (26' D, 15' W & 10' H) which will have AT screen with Triad LCR inwall Gold Speakers.
> 
> 1- should i treat the front wall with 1", 2" or 4" 703 Fiberglass? note that i am planning to place GIK corner bass traps in the front wall.
> 
> 2- i will place QRD diffusers, 2" absorption panels covered by GoM fabrics in the side walls in the areas that need to be treated (e.g., early reflection), but what do you suggest i should put inside the panels in other areas in the side walls where i dont plan to have any acoustic treatment? foam sponge, polyester batting .etc. to keep a uniform look and have no impact on the sound!
> 
> 3- my sweet spot will be 10' away from the back wall, so should i place diffusers only? or mix of diffusers and absorption panels?
> 
> 4- because of the space limitation i have in the front wall, can i place my two in-room Triad Gold Subwoofers in the front corners? if it is not a good idea, will EQ, Room treatment help to overcome the issues with this placement? or it is big no placement for dual subs!
> 
> 
> Thanks in advance for any advice and help.


I will eagerly watch for the answers you get on 1) and 3) - asked similar questions a few posts back.

As for 2), best bet for the right mix of QRD diffusion and absorption for first reflection treatment on side walls (thats how I read your plan ), would be to make/buy panels that can be tested in different positions and configurations (DAAAD, ADADA, AAAAA, DDADD, etc) - let your ears be the judge. Have a helper switch them around while you listen blindfolded to the same music loop.
It would be preferable soundwise to increase panel depth to 4-6" or same depth as QRD panels (for similar look), as it will make the panels absorb more broadband (extend the absorption deeper). The thinner the panels, the more unbalanced effect on the sound in the room. its the same argument for why 4" likely would be prefer able for the front wall (let's wait for the experts here  ).

For the rear half of the room, I would make GOM covered panels with NO fill, possibly with a couple of extra 1"x2" or 1"x4" (depending on panel depth) for crude scatter/deflection.
See for instance my DYI panels for my sloping sidewall, front half of room: LINK. 
These have alternating air sections and 2" OC 703 with 1.5" air gap sections, but the same principle applies - you can just skip the OC703. When the lights are dimmed, it is not possible to see where there is OC703 and where there is air. 

I would NOT fill the cavity out, crude deflection/scatter is preferable in the rear half of the room as compared to simple reflection.

I will be using QRD diffusors on the rear half of the sloping side walls, but just empty GOM covered panels on the vertical side walls in the rear half, with built in scatter strips. For the front half of vertical side walls, I will test, like suggested above.

I am not an accoustic, just a longtime reader of this thread.

Good luck


----------



## Romans828

Jacob B said:


> I will eagerly watch for the answers you get on 1) and 3) - asked similar questions a few posts back.


I am eagerly watching for answers to both of you guys posts...


----------



## hendry98

Jacob B said:


> I will eagerly watch for the answers you get on 1) and 3) - asked similar questions a few posts back.
> 
> "As for 2), best bet for the right mix of QRD diffusion and absorption for first reflection treatment on side walls (thats how I read your plan ), would be to make/buy panels that can be tested in different positions and configurations (DAAAD, ADADA, AAAAA, DDADD, etc) - let your ears be the judge. Have a helper switch them around while you listen blindfolded to the same music loop."
> 
> "For the rear half of the room, I would make GOM covered panels with NO fill, possibly with a couple of extra 1"x2" or 1"x4" (depending on panel depth) for crude scatter/deflection.
> 
> I would NOT fill the cavity out, crude deflection/scatter is preferable in the rear half of the room as compared to simple reflection."
> 
> 
> I am not an accoustic, just a longtime reader of this thread.
> 
> Good luck


Thanks for your feedback,, and i will try to use my ears but i also will try to learn to use REW to make my life easier as sometimes reading and numbers give you more info than your ear could tell. 

As for the empty panels, actually i got the same recommendation about keeping the panels empty rather than polyester batting or something. sweet 

then we both wait for others to advise regarding our other concerns.

I will check your build now, and best of luck you too!


----------



## blazar

hendry98 said:


> Thanks for your feedback,, and i will try to use my ears but i also will try to learn to use REW to make my life easier as sometimes reading and numbers give you more info than your ear could tell.
> 
> As for the empty panels, actually i got the same recommendation about keeping the panels empty rather than polyester batting or something. sweet
> 
> then we both wait for others to advise regarding our other concerns.
> 
> I will check your build now, and best of luck you too!


I have made my particular room to be almost all diffusion and I can tell you it sounds truly epic. I covered the entire side walls in diffusions and made every surface of the room bumpy that I possibly could. I just skipped all the equations and theory and just made every single surface non-flat that I could. I do have about a foot thick owens corning in the corners but the rest is various diffusion surfaces.


----------



## Jacob B

I dont think REW is made for measuring the effect on mid and highs from First reflection point treatment, and FRP panels' primary purpose is not bass absorption, so I think the only way to decide on what type of FRP treatment you prefer in YOUR room and setup will be to experiment. 
Going 4-6" for the FRP panels instead of 2" might be measurable with REW if you have a handfull of them on each side wall in the front half of room, but it will not tell you if you prefer less absorption of mid and highs and more scattering and diffusion instead.


----------



## Romans828

Is Gilford of Maine "Anchorage" fabric suitable for covering OC 703 for diy acoustic panels? I have seen conflicting opinions on this. My understanding is that it is fine for acoustic panels but not for covering speakers. Is this correct?


----------



## J

Romans828 said:


> Is Gilford of Maine "Anchorage" fabric suitable for covering OC 703 for diy acoustic panels? I have seen conflicting opinions on this. My understanding is that it is fine for acoustic panels but not for covering speakers. Is this correct?


That is what GIK told me also . The Anchorage fabric is nice stuff.

They will send you samples http://www.guilfordofmaine.com/acoustic


----------



## artur9

Jacob B said:


> I dont think REW is made for measuring the effect on mid and highs from First reflection point treatment


That's not true, AFAIK. There's the concept of sliced ETC that can give that information.

Check out the REW thread for more info. Basically, you can use REW to measure the ETC at different frequency bands.


----------



## hendry98

Romans828 said:


> Is Gilford of Maine "Anchorage" fabric suitable for covering OC 703 for diy acoustic panels? I have seen conflicting opinions on this. My understanding is that it is fine for acoustic panels but not for covering speakers. Is this correct?


Yes that's what i have been told as well, 

to give you a clearer comparison, Anchorage Fabric allows 80% of the sound to go through while Fr701 allows let's say 90%

so that's why you cannot use Anchorage to cover speakers, so only for acoustic panels.


----------



## hendry98

blazar said:


> I have made my particular room to be almost all diffusion and I can tell you it sounds truly epic. I covered the entire side walls in diffusions and made every surface of the room bumpy that I possibly could. I just skipped all the equations and theory and just made every single surface non-flat that I could. I do have about a foot thick owens corning in the corners but the rest is various diffusion surfaces.


Yeah that's what is all about, to have a good experience.

If I were you, i would try to replace some diffusers with absorption panels in the first/early reflection point, and compare the sound to see which one you like more.


----------



## KanosWRX

hendry98 said:


> Yes that's what i have been told as well,
> 
> to give you a clearer comparison, Anchorage Fabric allows 80% of the sound to go through while Fr701 allows let's say 90%
> 
> so that's why you cannot use Anchorage to cover speakers, so only for acoustic panels.


I am putting panels around the majority of my room, was thinking of putting absorption behind some, diffusion behind others, about 25% of each for a total of around 50%, the rest would just be dry wall behind the panel. Do you think that would be a good idea? I want to make sure the front reflection points are of course diffused or absorbed. But my other question is, my side and surround speakers will be behind the fabric too. If I went with the FR701, would that be ok?


----------



## hendry98

KanosWRX said:


> I am putting panels around the majority of my room, was thinking of putting absorption behind some, diffusion behind others, about 25% of each for a total of around 50%, the rest would just be dry wall behind the panel. Do you think that would be a good idea? I want to make sure the front reflection points are of course diffused or absorbed. But my other question is, my side and surround speakers will be behind the fabric too. If I went with the FR701, would that be ok?


I am no expert in acoustic treatment area, but i can tell you that you are in the right direction. 20-25% is a good ratio by most experts everywhere.

As for Fr701, yes you can do that. i am planning myself to place my surround speakers behind Fr701.

if you can move move the absorption/diffusion panels, then i suggest to try REW software with calibrated USB Mic to give you some correct readings to see if you have placed them properly or not.

but most important thing i have been told is the bass traps in the corners, which is i am planning to do as well.

properly just the front corners as the back corners might not be possible for me due to room limitation.


----------



## asoofi1

What brands are similar to linacoustic if I can't source it, just in case? Planning to deadwall plastic sandwich my fronstage wall behind the AT screen.


----------



## Clarence

asoofi1 said:


> What brands are similar to linacoustic if I can't source it, just in case?


McCormick Insulation is just a few miles from you. 

http://www.mccormickinsulation.com

That's where I got my Linacoustic, for this HT and in the previous house. I have half a roll left over if you want a good deal on it.


----------



## Brian Fineberg

How are these acoustic squares for sound treatment?

http://www.amazon.com/2x12x12-CHARCOAL-Acoustic-Soundproofing-Studio/dp/B00ATP9Q2O


----------



## asoofi1

Clarence said:


> McCormick Insulation is just a few miles from you.
> 
> http://www.mccormickinsulation.com
> 
> That's where I got my Linacoustic, for this HT and in the previous house. I have half a roll left over if you want a good deal on it.


Thanks! I'll check them out and PM you for your left over.


----------



## myfipie

Jacob B said:


> I dont think REW is made for measuring the effect on mid and highs from First reflection point treatment, and FRP panels' primary purpose is not bass absorption, so I think the only way to decide on what type of FRP treatment you prefer in YOUR room and setup will be to experiment.
> Going 4-6" for the FRP panels instead of 2" might be measurable with REW if you have a handfull of them on each side wall in the front half of room, but it will not tell you if you prefer less absorption of mid and highs and more scattering and diffusion instead.


REW is made to measure not only the low end but also the upper frequencies. You can view the ETC to make sure you have covered all early reflection points properly.


----------



## myfipie

hendry98 said:


> Yeah that's what is all about, to have a good experience.
> 
> If I were you, i would try to replace some diffusers with absorption panels in the first/early reflection point, and compare the sound to see which one you like more.


For the most part I agree, but also small rooms have most of the problems on the low end so having plenty of bass trapping in corners is highly recommend.


----------



## myfipie

Brian Fineberg said:


> How are these acoustic squares for sound treatment?
> 
> http://www.amazon.com/2x12x12-CHARCOAL-Acoustic-Soundproofing-Studio/dp/B00ATP9Q2O


Any company that uses "Soundproofing Studio Foam Tiles" pretty much does not know anything about room acoustics. Soundproofing is about isolation, which foam does not do. Also it says the NRC is 65 which does not seem very good at all. I have a feeling it is not real acoustical foam but some kind of knock off.


----------



## Jacob B

Glenn, 
Do you have any comments to Hendry98's questions 20 posts back - especially the one about the front wall treatment? I asked a similar question on the previous page in the Thread.
To treat or not to threat the entire front wall behind an AT screen - and how thick (if Price is not a factor)...?


cheers,
jacob


----------



## Laidback

Jacob B said:


> Glenn,
> Do you have any comments to Hendry98's questions 20 posts back - especially the one about the front wall treatment? I asked a similar question on the previous page in the Thread.
> To treat or not to threat the entire front wall behind an AT screen - and how thick (if Price is not a factor)...?
> 
> 
> cheers,
> jacob


YES, Glenn,
Especially if there needs to be a membrane added to the back of fabric panels/in front of fluffy (6 mil visqueen?). I'm ready to measure with REW to get base line before I add anything to the room. I'm sure the graph will look HORRIBLE!! LOL


----------



## KanosWRX

Just thinking about how their are all of these ideas of having diffusion and absorption all around the room at different points, it seems the main points are the front reflection points and the front wall. I know most people say 25-50% coverage of your room is the ideal amount so its not too reflective and not too dead sounding. My question is, that 25-50% is usually done with ~2" absorption or diffusion panels placed throughout the room. What if you did 1" absorption or diffusion on ~90% of your walls (not 100% as you might have door's and columns)... would that be just as effective? Again, still taking into consideration you might need more at front reflection points and the front wall. Just thinking for the rest of the room outside of those two main areas would that effectively give you a good level of both reflection and absorption? Just an idea as you would have a uniform level of some absorption but then since its only 1" you would still get some reflection so its not dead. Anyone have any thoughts on that?


----------



## HopefulFred

KanosWRX said:


> My question is, that 25-50% is usually done with ~2" absorption or diffusion panels placed throughout the room. What if you did 1" absorption or diffusion on ~90% of your walls (not 100% as you might have door's and columns)... would that be just as effective?


That's not going to be a good choice. Think of the thickness of the treatment as determining the bandwidth of the absorber - thicker means larger band - effectiveness to lower frequencies. When you limit your treatments to the percentage of surface area you are talking about, the unspoken assumption is that those treatments or absorbers are broad band. Thin and thick absorbers are both good at absorbing high frequency sound - either can take a little of the sparkle out of a room. On the other hand, removing the midrange reflections that tend to detract from speech intelligibility and color frequency response in a bad and noticeable way requires the deeper treatments (with some exceptions).

The percentage estimates are based on area, not volume - so spreading them out thinner isn't going to do it.


----------



## KanosWRX

HopefulFred said:


> That's not going to be a good choice. Think of the thickness of the treatment as determining the bandwidth of the absorber - thicker means larger band - effectiveness to lower frequencies. When you limit your treatments to the percentage of surface area you are talking about, the unspoken assumption is that those treatments or absorbers are broad band. Thin and thick absorbers are both good at absorbing high frequency sound - either can take a little of the sparkle out of a room. On the other hand, removing the midrange reflections that tend to detract from speech intelligibility and color frequency response in a bad and noticeable way requires the deeper treatments (with some exceptions).
> 
> The percentage estimates are based on area, not volume - so spreading them out thinner isn't going to do it.


So due to the design and layout of my room, the best I am going to get is about a 1" gap between my drywall and the fabric panels  I know this won't be an ideal situation. I do plan on having 2" of linacoustic on the front wall, and plan to build bass traps in the front corners as well. Unfortunately the side and rear walls won't be ideal, but I am thinking I can go with a combination of absorption and diffusion to hopefully get a decent solution. My plan is to take some 1-1/4" square pieces of wood that's about 8 feet tall, cut them in half, then slice them diagonal so they would be like triangles attached to the drywall behind my fabric panels for diffusion. I could take these "triangle ripple panels" 4' high x 2' wide and place them in the three sections of my left and right walls (the wall is about 20' long with two columns in the middle). In addition to that I would have linacoustic (only one inch  ) for absorption, again can make them 4' x 2' or even more. Then do the same on the back wall, have two of my triangle diffusion 4'x2' pannels on the back wall, and more linacoustic. Do you think this will be a half way decent approach? My riser will also be built as a giant bass trap following the guidelines found here on the forum with the vents in the rear. I guess it will be better then nothing and will hopefully get me 75% of the way there  Any other ideas are welcome, thanks!


----------



## HopefulFred

I'm sure you'll get close, and some EQ can probably help more.

I would encourage you to do two things as you finalize your plans and move to installation. Learn to listen carefully and get a feel for what your space sounds like - then make changes carefully and slowly, so you can be conscious of the changes you make and whether you're making improvements (and/or learn to make acoustic measurements to go along with that). Second, look into slat diffusors or other binary amplitude diffusors. Your triangle idea will work as a reflector - at certain frequencies in one direction and at others in another direction.


----------



## ellisr63

KanosWRX said:


> So due to the design and layout of my room, the best I am going to get is about a 1" gap between my drywall and the fabric panels  I know this won't be an ideal situation. I do plan on having 2" of linacoustic on the front wall, and plan to build bass traps in the front corners as well. Unfortunately the side and rear walls won't be ideal, but I am thinking I can go with a combination of absorption and diffusion to hopefully get a decent solution. My plan is to take some 1-1/4" square pieces of wood that's about 8 feet tall, cut them in half, then slice them diagonal so they would be like triangles attached to the drywall behind my fabric panels for diffusion. I could take these "triangle ripple panels" 4' high x 2' wide and place them in the three sections of my left and right walls (the wall is about 20' long with two columns in the middle). In addition to that I would have linacoustic (only one inch  ) for absorption, again can make them 4' x 2' or even more. Then do the same on the back wall, have two of my triangle diffusion 4'x2' pannels on the back wall, and more linacoustic. Do you think this will be a half way decent approach? My riser will also be built as a giant bass trap following the guidelines found here on the forum with the vents in the rear. I guess it will be better then nothing and will hopefully get me 75% of the way there  Any other ideas are welcome, thanks!





HopefulFred said:


> I'm sure you'll get close, and some EQ can probably help more.
> 
> I would encourage you to do two things as you finalize your plans and move to installation. Learn to listen carefully and get a feel for what your space sounds like - then make changes carefully and slowly, so you can be conscious of the changes you make and whether you're making improvements (and/or learn to make acoustic measurements to go along with that). Second, look into slat diffusors or other binary amplitude diffusors. Your triangle idea will work as a reflector - at certain frequencies in one direction and at others in another direction.


I agree, make some panels, re eq, and then listen to what has changed... Make some more panels , eq, and see what has changed this time. When I was doing my setup i expected one thing to happen to the sound, but usually got something else which was not expected, but made a very nice improvement in the sound. One thing that surprised me was we were tuning the room for HT use mainly, but found out it was making a dramatic improvement in stereo sound too. I love the way my setup turned out, but now I am going to make some diffusion panels, and see what happens when they are added to the room. If I don't like the way it changes the sound i can remove them, and not have spent a ton of money either to find out.

One thing that is imperative is to run Audyssey Or what ever other Room EQ software you are using) after each modification. I also would pick some recordings that you like, and that show off all the details, ie spaciousness, clarity,depth of soundstage etc. I have several that i use, and during the testing stages i found more to use (some of which didn't sound that good when i started but really bloomed as the room was tuned). I also have a movie (Pitch Perfect... Don't laugh, give it a listen and you will find it is an excellent reference Bluray) thatI have used for testing from the first stage of the mods, and it has gotten better and better as the room improved. Enjoy the journey as it is half the fun.


----------



## KanosWRX

ellisr63 said:


> I agree, make some panels, re eq, and then listen to what has changed... Make some more panels , eq, and see what has changed this time. When I was doing my setup i expected one thing to happen to the sound, but usually got something else which was not expected, but made a very nice improvement in the sound. One thing that surprised me was we were tuning the room for HT use mainly, but found out it was making a dramatic improvement in stereo sound too. I love the way my setup turned out, but now I am going to make some diffusion panels, and see what happens when they are added to the room. If I don't like the way it changes the sound i can remove them, and not have spent a ton of money either to find out.
> 
> One thing that is imperative is to run Audyssey Or what ever other Room EQ software you are using) after each modification. I also would pick some recordings that you like, and that show off all the details, ie spaciousness, clarity,depth of soundstage etc. I have several that i use, and during the testing stages i found more to use (some of which didn't sound that good when i started but really bloomed as the room was tuned). I also have a movie (Pitch Perfect... Don't laugh, give it a listen and you will find it is an excellent reference Bluray) thatI have used for testing from the first stage of the mods, and it has gotten better and better as the room improved. Enjoy the journey as it is half the fun.


^^^ Thanks for all the advice!! I'll look into making some slat diffuses as well. I'll probably make 4'x2' panels of the different types (diffusion and absorption) and then try them in different configurations like you said. Then when I have it the way I like ill cover it all with the acoustic fabric so you don't see the stuff behind. I'll be sure to post some pics


----------



## Al Sherwood

Jacob B said:


> Well, I AM using an AT screen and it is exactly for that reason I understood treating the entire wall was useful.
> 
> However, I also understood that treating the front wall will negate reflections from the side and rear surrounds messing up the front soundstage.
> 
> *I believe treating any surface in the room with a thin absorber is done due to economic or space availability reasons. Any porous absorber should - for strictly acoustic reasons - be broadband, i.e. at least 4", or maybe min 2-3" with 1" space - as in your linked articles.*
> 
> That argument would lead to the conclusion that with an AT screen, treating the entire front wall should be with at least 4" porous absorber, in my case 60 kg/m3 Knauf RS60 rockwool batts.
> 
> Another option could be to place a 2'x4' four inch absorber behind each LCR speaker, rather than the entire wall.
> However, that does not fully address reflections from the backside of the AT screen, only backward bass radiation from the LCR speakers.
> And what about the rear wall reflection of the LCR speakers, coming back to reflect off the front wall, and messing up the front soundstage?
> (I guess the latter can be addressed by treating the rear wall either with 4-6" absorption to _reduce_, or with diffusors in order to _delay_ the return of the LCR sound waves to the front wall - or a mix... BUT where does this rear wall talk leave the front wall treatment??)
> 
> *Would some of the acoustic experts care to comment on this?*





Laidback said:


> I am in the same boat as Jacob B. I have 2" Roxul on front wall with AT screen. I want to know if I should add layer of pink n fluffy on top of that, remove the Roxul and go all pink or add another layer or 2 of Roxul? I figure I can make a decent little frame to hold back the fluffy with 1x4s and then staple fabric to it to help keep it in place. I am assuming that the pink n fluffy we are talking about is not paper backed.



Me three I think!


I am embarking on a room 21x16x8 and will have a screen wall at the front, with hopefully both (large) subs up there as well... the more I read the less that I am convinced that I have determined what I want to do about treatments!


----------



## ellisr63

Al Sherwood said:


> Me three I think!
> 
> 
> I am embarking on a room 21x16x8 and will have a screen wall at the front, with hopefully both (large) subs up there as well... the more I read the less that I am convinced that I have determined what I want to do about treatments!


Your room is fairly close to my room dimensions. We ran 3 2x4 panels on each wall (first reflections), 6 panels on the ceiling (first reflections), with 9" on the back wall for a bass trap (covered with rubber sheeting), and 3" on the front wall too.

You might want to consider a sub in the front and a sub in the rear of the room.... (page 15) http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/multsubs.pdf


----------



## KanosWRX

Have a couple questions about materials.

First, I was planning on going with 2" linacoustic material on the front wall (I will have a false wall so the whole wall behind that will be sound absorption material). But I am looking over the numbers here, http://www.bobgolds.com/AbsorptionCoefficients.htm and these are the specs for linacoustic at 2"

Sorry for the bad formatting.. 

PRODUCT	THICKNESS	DENSITY 125HZ 250HZ 500HZ 1000HZ 2000HZ 4000HZ NRC
Linacoustic IS Black	1" (25mm)	1.5pcf (24kg/m3) _0.09 _0.29 _0.67 _	0.89 _1.03 _0.99 _	0.7
Linacoustic RC	2" (51mm) _ 0.25 _ 0.66 _ 1 _ 1.05 _ 1.02 _ 1.01 _ 0.95

Not that great at absorbing the low ranges.

Now I could also go with Roxul AFB, which seems to be better over all the ranges but especially lower freq.

RODUCT	THICKNESS	DENSITY 125HZ 250HZ 500HZ 1000HZ 2000HZ 4000HZ NRC
AFB	3" (75mm)	2.5 pcf (40 kg/m3) _0.52 _	0.96 _1.18 _1.07 _1.05 _	1.05 _1.05
AFB	4" (100mm)	2.5 pcf (40 kg/m3) _0.86 _1.11 _1.2 _1.07 _1.08 _1.07 _1.1

Would it be better to just get 3" or 4" installed behind my false wall instead of the linacoustic material? seems like its much better at sound absorption or am I missing something else?


----------



## hendry98

For early reflection where i plan to have 2" absorption panels, the wife does not seem to approve fiberglass covered by GoM fabrics 

what if i try StudiofoamPro 1.5" and leave 1" gap from the wall, will they perform close to fiberglass 2"??

StudiofoamPro: http://www.amazon.com/Auralex-StudiofoamPro-1-5-Inch-Acoustic-Absorption/dp/B004S2FYP2


----------



## KanosWRX

hendry98 said:


> For early reflection where i plan to have 2" absorption panels, the wife does not seem to approve fiberglass covered by GoM fabrics
> 
> what if i try StudiofoamPro 1.5" and leave 1" gap from the wall, will they perform close to fiberglass 2"??
> 
> StudiofoamPro: http://www.amazon.com/Auralex-StudiofoamPro-1-5-Inch-Acoustic-Absorption/dp/B004S2FYP2


My wife hated the idea of panels on the walls too, I am not sure having foam panels will be any better then 2" fiber panels covered by GOM. What my wife did ok was covering the entire walls in fabric, then putting treatments behind that. Of course ill have trim and columns as well so its not all fabric, but it will at least look consistent and pass the WAF.


----------



## Al Sherwood

ellisr63 said:


> Your room is fairly close to my room dimensions. We ran 3 2x4 panels on each wall (first reflections), 6 panels on the ceiling (first reflections), with 9" on the back wall for a bass trap (covered with rubber sheeting), and 3" on the front wall too.
> 
> You might want to consider a sub in the front and a sub in the rear of the room.... (page 15) http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf


 
Thanks for the link to the Harman Sub article, will be reading this weekend... Also just started looking at your HT build thread, noticed right away that not only do you also have 2- DTS-10's (like me) but also a interest in Klipsch speakers! This could be interesting!


----------



## AXLCMT

*Can Guilford of Maine (GOM) Series "Sensa" be used to cover Speakers?*

Can Guilford of Maine (GOM) Series "Sensa" be used to cover Speakers?


----------



## Jacob B

Al Sherwood said:


> Me three I think!
> 
> 
> I am embarking on a room 21x16x8 and will have a screen wall at the front, with hopefully both (large) subs up there as well... the more I read the less that I am convinced that I have determined what I want to do about treatments!





ellisr63 said:


> Your room is fairly close to my room dimensions. We ran 3 2x4 panels on each wall (first reflections), 6 panels on the ceiling (first reflections), with 9" on the back wall for a bass trap (covered with rubber sheeting), and 3" on the front wall too.
> 
> You might want to consider a sub in the front and a sub in the rear of the room.... (page 15) http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/multsubs.pdf


Still would like some of the acoustic experts to comment on front wall treatment...
Why has standard treatment behind an AT screen been 1-2" linaccoustics or OC703? 
Why not 4-6", if there is space?
Why not just absorption behind the three LCR speakers?


Even though it is a good point to listen and measure after each incremental treatment, it is not really practical, since a treatment plan is somewhat holistic. For instance, treating the rear wall with Broadband absorption will affect LCR speaker reflections coming back and reflecting off the front wall. 


Likewise, I have treated my entire ceiling with 5" absorption, with a built-in fiberoptic står ceiling. It would not really be practical to tear it down... Either 5" OC703 in the ceiling is good for a (any) room or it is not - or what??


Jacob


----------



## ellisr63

Jacob B said:


> Still would like some of the acoustic experts to comment on front wall treatment...
> Why has standard treatment behind an AT screen been 1-2" linaccoustics or OC703?
> Why not 4-6", if there is space?
> Why not just absorption behind the three LCR speakers?
> 
> 
> Even though it is a good point to listen and measure after each incremental treatment, it is not really practical, since a treatment plan is somewhat holistic. For instance, treating the rear wall with Broadband absorption will affect LCR speaker reflections coming back and reflecting off the front wall.
> 
> 
> Likewise, I have treated my entire ceiling with 5" absorption, with a built-in fiberoptic står ceiling. It would not really be practical to tear it down... Either 5" OC703 in the ceiling is good for a (any) room or it is not - or what??
> 
> 
> Jacob


Our back wall is a bass trap which is why we used 9" of R60 and then covered it with rubber sheeting. I believe the reason for treating the wall behind the screen with only a few inches is to help the imaging of the front 3 channels more. Our whole room is fabric panels so in our situation it is not a problem to pull down a panel and add absorption or diffusion and replace the panel. All of my treatments were at the suggestion of GIK Acoustics.


----------



## hendry98

KanosWRX said:


> My wife hated the idea of panels on the walls too, I am not sure having foam panels will be any better then 2" fiber panels covered by GOM. What my wife did ok was covering the entire walls in fabric, then putting treatments behind that. Of course ill have trim and columns as well so its not all fabric, but it will at least look consistent and pass the WAF.


Well in my situation is kinda different as the wife does not mind the panels, it is just the material behind the panels is the issue. she thinks that having fiberglass covered with GoM is risky 

so instead of 2" fiberglass, i want to see if i can go with Studiofoam Pro, which has 0.9 NRC. 

i know it is less effective than fiberglass, but will i notice the difference?

if not, or slight difference, then Studiofoam Pro might do the job as it passes WAF


----------



## KanosWRX

AXLCMT said:


> Can Guilford of Maine (GOM) Series "Sensa" be used to cover Speakers?


According to GOMs website, 

NRC of fabric in front of anechoic termination, .95, I think after 1000hz it starts to absorb a little more, but not much.


----------



## KanosWRX

hendry98 said:


> Well in my situation is kinda different as the wife does not mind the panels, it is just the material behind the panels is the issue. she thinks that having fiberglass covered with GoM is risky
> 
> so instead of 2" fiberglass, i want to see if i can go with Studiofoam Pro, which has 0.9 NRC.
> 
> i know it is less effective than fiberglass, but will i notice the difference?
> 
> if not, or slight difference, then Studiofoam Pro might do the job as it passes WAF


Oh she doesn't like the idea of fiber glass fibers in the air, is that what she is afraid of? What if instead you used mineral wool, safer then fiberglass, and can have the same acoustic properties.


----------



## hendry98

KanosWRX said:


> Oh she doesn't like the idea of fiber glass fibers in the air, is that what she is afraid of? What if instead you used mineral wool, safer then fiberglass, and can have the same acoustic properties.


Yeah correct, she hates the idea of fiberglass.

mineral wool is kinda similar, isn't it?


----------



## BasementBob

Asbestos fibers are bad for you.

But fiberglass and rockwool don't affect home insulation installers, so they're safe. (beyond the usual skin itching problems)
And you're going to be wrapping yours in GoM fabric (and possibly polyester quilt batting), so they'll affect you orders of magnitude less than home insulation installers.

The International Agency on Cancer Research (IACR) removed fiberglass from its “possibly carcinogenic to humans” list in 2001.

This is the one I accept 100%:
http://recording.org/threads/exposing-the-myths-of-fiberglass.13951/

The below summarizes some of the concepts about fiber length, and looks correct.
The last paragraph, about Styrene, I have no opinion on as to if that's relative to us, but I doubt it. I believe Styrene requires very high levels to be harmful -- i.e. its a problem during manufacture, not by the time we get it.



> Everyone has heard about the association between lung cancer and asbestos. Since some forms of asbestos are similar in appearance to fiberglass fibers, many people wonder if handling fiber-glass could also result in the development of cancer or other serious health hazards. Scientists have made over 400 studies of fiberglass in an attempt to answer this question. The conclusion is that it will not, because its properties are very different from asbestos. OSHA confirmed these findings in 1991 when it decided to regulate fiberglass as a nuisance dust, and not as a cancer causing agent. The state of California, neverth less, still requires that fiberglass be labeled as a potential cancer causing agent.
> 
> The principal difference between glass fibers and asbestos fibers is their size and the way the fibers break down. Glass fibers are cylindrical single fibers that can never split lengthwise; they only break across the fiber. As they break, they form tiny fragments that no longer have the properties of a fiber. Asbestos fibers, on the other hand, are always present as bundles, never as a single fiber. Asbestos fibers fracture only lengthwise when the bundles break apart, releasing thousands of long tiny fibers. When these are inhaled, they become trapped in the small sacs of the lungs known as alveoli. Because asbestos fibers are long, sharp, and irritating to lung tissue, the alveoli close up and trap them in the lungs. This eventually results in the lungs becoming hard, fibrous and inelastic. Over time, the continued irritations cause cancer in some individuals.
> 
> Because fiberglass breaks across the fiber to form tiny fragments, the tissue response is very different when these particles are inhaled. When fiberglass fragments are inhaled and deposited in the small air sacs of the lung, the alveoli do not close up and trap the particles. The particles are expelled from the alveoli and there is a rapid clearance of fiberglass dust particles from the lungs.
> 
> However, fiberglass presents other problems-such as irritations of the eyes, skin, or respiratory tract. The mechanical action of the fibers scraping against skin may cause a condition known as dermatitis. To protect yourself, wear long sleeve shirts and pants to keep the fibers off your skin, and wear clean clothes every day. Gloves and eye protection may also help. Use soap and warm water to remove any fibers that you do get on your skin. Dust is produced when mat or cloth is rolled out, where chopper guns are used, and in finishing operations where flashing is removed or sanding occurs. So always wear a dust mask in these areas to help avoid inhaling glass fibers.
> 
> The primary hazard associated with fiberglass is the chemicals used during the fabrication or lay up process. Styrene monomer, or raw resin, is catalyzed with an organic peroxide; the most common is methyl ethyl ketone peroxide. Cobalt compounds, often used as accelerators, can result in allergic dermatitis or asthma like conditions. Acetone is a central nervous system depressant used for clean up of tools, utensils, and spray equipment. The important thing to remember about these chemicals is that they are health hazards when inhaled; proper respiratory equipment must be worn and adequate ventilation provided. You should also be aware that these chemicals can form flammable or explosive concentrations at normal room temperatures, so proper handling and ventilation is essential.
> 
> Working with fiberglass material should not be dangerous if you are properly trained, and if you use appropriate protective equipment. Be sure to do so!
> 
> http://www.toolboxtopics.com/Gen Industry/Is Fiberglass a Health Hazard.htm


----------



## KanosWRX

hendry98 said:


> Yeah correct, she hates the idea of fiberglass.
> 
> mineral wool is kinda similar, isn't it?


Mineral wool is much better to install I know then fiberglass, not itchy like the pink stuff. That to me means its less irritating in general. I think your wife would be ok with mineral wool, tell her how its from a natural substance, rocks.


----------



## BasementBob

ROXUL insulation is a rock-based mineral fiber insulation comprised of Basalt rock and Recycled Slag. Basalt is a volcanic rock(abundant in the earth), and slag is a by-product of the steel and copper industry. The minerals are melted and spun into fibers.
-- http://www.roxul.com/stone+wool/overview/faq


----------



## Al Sherwood

KanosWRX said:


> Mineral wool is much better to install I know then fiberglass, not itchy like the pink stuff. That to me means its less irritating in general. I think your wife would be ok with mineral wool, tell her how its from a natural substance, rocks.



Not that fiberglass contains any real bad things either:


The basic raw materials for fiberglass products are a variety of natural minerals and manufactured chemicals. The major ingredients are silica sand, limestone, and soda ash. Other ingredients may include calcined alumina, borax, feldspar, nepheline syenite, magnesite, and kaolin clay, among others.

Read more: http://www.madehow.com/Volume-2/Fiberglass.html#ixzz3RjZL3Xgp


----------



## ellisr63

BasementBob said:


> ROXUL insulation is a rock-based mineral fiber insulation comprised of Basalt rock and Recycled Slag. Basalt is a volcanic rock(abundant in the earth), and slag is a by-product of the steel and copper industry. The minerals are melted and spun into fibers.
> -- http://www.roxul.com/stone+wool/overview/faq


We used it throughout our HT for all of our acoustic panels... Love it, and the price was not bad either.


----------



## hendry98

Ohh man it is pretty hard to find other stuff near my area, just the fiberglass frk!

now, if i add a thin layer (let's say 0.5 inch ) of sponge/foam between GoM fabric and fiberglass, would that be a possible solution? this is something would pass WAF!

i think it could be a bonus, because rigid fiberglass would reflect some of high frequencies, so the layer in front of it would absorb those frequencies, right?


----------



## ellisr63

hendry98 said:


> Ohh man it is pretty hard to find other stuff near my area, just the fiberglass frk!
> 
> now, if i add a thin layer (let's say 0.5 inch ) of sponge/foam between GoM fabric and fiberglass, would that be a possible solution? this is something would pass WAF!
> 
> i think it could be a bonus, because rigid fiberglass would reflect some of high frequencies, so the layer in front of it would absorb those frequencies, right?


Have you tried Home Depot or Lowes... Special Order?


----------



## KanosWRX

So since I only have 1" of depth to work with I am looking at whatever I can fit in there for diffusion and absorption. I found these, what do you think for the diffusion panels?

http://www.sweetwater.com/store/detail/DSTR


----------



## ellisr63

KanosWRX said:


> So since I only have 1" of depth to work with I am looking at whatever I can fit in there for diffusion and absorption. I found these, what do you think for the diffusion panels?
> 
> http://www.sweetwater.com/store/detail/DSTR


What frequencies are you trying to effect? I think 1" deep is only going to effect the very high frequencies.


----------



## KanosWRX

ellisr63 said:


> What frequencies are you trying to effect? I think 1" deep is only going to effect the very high frequencies.


 That's what I am worried about, because my door is so far over in a corner I only had a gap for 1" behind my fabric on the walls for any treatments . I know it's not ideal, just trying to come up with the best I can do with my situation.


----------



## hendry98

ellisr63 said:


> Have you tried Home Depot or Lowes... Special Order?


yeah i have, but only could fiberglass stuff. (and i dont live in U.S. by the way)


----------



## bgtighe23

I am ready to get treatments for my room, I know where I want to placement, but I'm not sure what brand or kind I need. That's basically where I'm stuck. Is there a link y'all can post where some good treatments are?


----------



## ellisr63

hendry98 said:


> yeah i have, but only could fiberglass stuff. (and i dont live in U.S. by the way)


What country are you in... I know that my Roxul was ordered from Canada.


----------



## hendry98

ellisr63 said:


> What country are you in... I know that my Roxul was ordered from Canada.


I tried to see online, but it seems for international they charge me for the dimensional rather than actual weight, so it is gonna be pretty expensive to order those materials.

however, i found some are suggesting to wrap the fiberglass with very thin plastic, and then place 1-1.5" acoustic foam. after that you can cover your complete panel with your fabric. 

such approach, does it really work for for side walls? 

I mean technically speaking, Mid & HF will be absorbed by your thin foam, and LF will pass the foam and the plastic but will be absorbed by fiberglass. Right?

unless i am not getting the idea of sound absorption correctly


----------



## myfipie

hendry98 said:


> For early reflection where i plan to have 2" absorption panels, the wife does not seem to approve fiberglass covered by GoM fabrics
> 
> what if i try StudiofoamPro 1.5" and leave 1" gap from the wall, will they perform close to fiberglass 2"??
> 
> StudiofoamPro: http://www.amazon.com/Auralex-StudiofoamPro-1-5-Inch-Acoustic-Absorption/dp/B004S2FYP2


I would jump on GOM's website, with the wife and order a bunch of different colors. They have a lot of lines that look pretty slick. Much better then foam, IMO. GOM will send these to you free of charge in 2 days.


----------



## myfipie

> however, i found some are suggesting to wrap the fiberglass with very thin plastic, and then place 1-1.5" acoustic foam. after that you can cover your complete panel with your fabric.


I would never do that. The 1.5" acoustic foam is not going to really work below around 600hz and the plastic is going to reflect some sound you want to absorb. In the early reflection points you want to absorb as much of the over all sound that you can.


----------



## Jacob B

*Glenn,*
Would you like to offer some comments on the front wall questions posed by Hendry98 and myself earlier? 
In other words, 2" vs 4" absorbing treatment of front wall, and the question of entire wall vs. behind speakers? As well as how these questions combine with how you should treat your rear wall?
See detailed questions above  

THANKS!!!


----------



## hendry98

myfipie said:


> I would never do that. The 1.5" acoustic foam is not going to really work below around 600hz and the plastic is going to reflect some sound you want to absorb. In the early reflection points you want to absorb as much of the over all sound that you can.


Well I found this acoustic foam from a well known company who published NRC of this product: http://www.auralex.com/wp-content/uploads/2013/10/Studiofoam-Pro-Spec-Sheet-v4.pdf 

note that this acoustic foam can do well below 600hz up to 400hz, but below that it does not perform well!

so that's my point here, to have 2" fiberglass behind it to handle those low frequencies!

logically speaking this should work right? 

at least having acoustic foam in front the fiberglass and the whole thing wrapped with acoustic fabric passes WAF

what do you think?


----------



## myfipie

hendry98 said:


> Well I found this acoustic foam from a well known company who published NRC of this product: http://www.auralex.com/wp-content/uploads/2013/10/Studiofoam-Pro-Spec-Sheet-v4.pdf
> 
> note that this acoustic foam can do well below 600hz up to 400hz, but below that it does not perform well!
> 
> so that's my point here, to have 2" fiberglass behind it to handle those low frequencies!
> 
> logically speaking this should work right?
> 
> at least having acoustic foam in front the fiberglass and the whole thing wrapped with acoustic fabric passes WAF
> 
> what do you think?


Logically yes, but would not put any kind of plastic between them. Unless someone has tested this in a lab I would play it safe.


----------



## myfipie

Jacob B said:


> *Glenn,*
> Would you like to offer some comments on the front wall questions posed by Hendry98 and myself earlier?
> In other words, 2" vs 4" absorbing treatment of front wall, and the question of entire wall vs. behind speakers? As well as how these questions combine with how you should treat your rear wall?
> See detailed questions above
> 
> THANKS!!!


Hey Jacob,

Sorry I don't see the question above, but generally speaking for the front wall I like to use no less then 4". In fact if possible I like it thicker. As far as coverage, the more the better. If you start to loss to much upper frequencies then I would use a slat design (like our Scatter Plates) and or a membrane. 
For the back wall, generally speaking I like to go as THICK as possible with trapping and cover as much of the wall space as possible. If budget is there I will also throw in something tuned and diffusion for good measure.  In the end though every room is going to be different.


----------



## Jacob B

myfipie said:


> Hey Jacob,
> 
> Sorry I don't see the question above, but generally speaking for the front wall I like to use no less then 4". In fact if possible I like it thicker. As far as coverage, the more the better. If you start to loss to much upper frequencies then I would use a slat design (like our Scatter Plates) and or a membrane.


If you cover the entire front AND back wall, in addition the entire ceiling, as I have, plus 1st relection points on the sidewalls, it seems you would be treating a lot more than 50% surface, as I hear is the recommended number? 

Would you use something like pond liner as membrane above, below, and to the sides of the screen - leaving the area directly behind the AT screen with no membrane?
Or would a slat design be preferable to this - and then everywhere on the front wall, or around the screen but not behind it? _As I understand it,_ the area directly behind the screen should be treated due to reflections off the backside of the AT screen? 
Should you worry about reflections off the front wall from the rear surrounds, or is it the backwall reflections of the LCR that is the main problem? In the latter case, this can be taken care of on the rear wall, right? (see below) 



myfipie said:


> For the back wall, generally speaking I like to go as THICK as possible with trapping and cover as much of the wall space as possible. If budget is there I will also throw in something tuned and diffusion for good measure.  In the end though every room is going to be different.


I already bought GIK versifusors for the upper 1/3 of the back wall. Below them (below 150 cm / 5'), the second row of seats will be blocking line of sight from the front subs and LCR speakers to the back wall. There is a three foot wide walking area behind the 2nd row before the back wall. 
The way I see it, the two rows of Berkline 090 with 4-8 people in them should be acting as bass absorbers between the front subs and the rear wall, *negating the need for bass trapping here?* And mid and high freq reflections of the LCR speakers will not hit the back wall below 5', only the area covered by versifusors - the (3) versifusors will be the only part of the back wall visible from the front row...
In addition, the rear half of my sloping side walls will have four versifusors in each side.

Does this sound reasonable?

Cheers,
Jacob


----------



## myfipie

> If you cover the entire front AND back wall, in addition the entire ceiling, as I have, plus 1st relection points on the sidewalls, it seems you would be treating a lot more than 50% surface, as I hear is the recommended number?


Keep in mind that in a full acoustic build out you are taking every inch (well kind of) into account, so using a percentage really is not correct. You might have some areas that are reflective, others that are are absorptive or diffused/scattering. It is all of the this that works as a "unit" in the room. Their are no "rules" as all rooms are different and what you might like may not apply to the next person. Over all we are going for a even response (decay and frequency) but no 2 rooms are going to be the some for a host of reasons (shape, construction and so on). 



> Would you use something like pond liner as membrane above, below, and to the sides of the screen - leaving the area directly behind the AT screen with no membrane?


I have never worked with pond liner, but would seem to me it would not reflect that much upper frequencies, if that is what you are going for or need. 



> I already bought GIK versifusors for the upper 1/3 of the back wall. Below them (below 150 cm / 5'), the second row of seats will be blocking line of sight from the front subs and LCR speakers to the back wall. There is a three foot wide walking area behind the 2nd row before the back wall.
> The way I see it, the two rows of Berkline 090 with 4-8 people in them should be acting as bass absorbers between the front subs and the rear wall, negating the need for bass trapping here? And mid and high freq reflections of the LCR speakers will not hit the back wall below 5', only the area covered by versifusors - the (3) versifusors will be the only part of the back wall visible from the front row...
> In addition, the rear half of my sloping side walls will have four versifusors in each side.


The human body does absorb sound but I would not call them "bass traps" or think you can go without them because of bodies in the room. BTW we talking about small room acoustics, not things like concert halls. 

Over all if you want to dig this deep into your room then I would test it with REW and learn how to understand what you have or hire someone to give you a hand. With that said though just doing the normal things like trapping in corners, covering early reflection points and THICK absorption for the back wall will get you pretty far in-front of the power curve.


----------



## highfigh

bgtighe23 said:


> I am ready to get treatments for my room, I know where I want to placement, but I'm not sure what brand or kind I need. That's basically where I'm stuck. Is there a link y'all can post where some good treatments are?


If you need sources who can help determine what you need, here's a link with suppliers in Houston-

https://www.google.com/search?q=Contractor's+Acoustical+Supply+Houston&ie=utf-8&oe=utf-8


----------



## AXLCMT

*Fabric Panel+Furring Strips - Total Depth - (with velcro) 1" Linacoustic*

Question:
*In order to avoid any "bulges" of 1" Linacoustic and Cotton Batting from pressing out against the tightened fabric (because hypothetically if I make the mistake of designing the combined depth dimensions of the furring strip and fabric panels), how "thick/deep" should I purchase regarding the depth size of furring strips for Fabric Panels (considering also the depth of the velcro dimensions when installed)?*

Fabric Panels+Furring Strips - Depth Dimensions (considering Linacoustic thickness)
Fabric Panel Design:
1. Furring strips on the wall on all edges of the edges of the Fabric Panels. 
Linacoustic on bottom half of the wall and Dacon Cotton Batting from Joanne's Fabric on the upper part of the walls 
(ear height and above) divided by furring strips.

2. 1" thickness of Linacoustic and however many layers of Dacon Cotton Batting from Joanne's fabric will be applied directly 
to the drywall using 3M 77 Spray Adhesive.

3. Fabric Panels will be made of either Plywood or MDF with GOM fabric stapled to the backs of the Fabric Panels and will attach to the furring strips via Velcro.

Is it ok if the there is some "space" between the fabric and the 1" Linacoustic/Cotton? How close should the fabric be relative to the 1" Linacoustic and Cotton Batting? Should the Fabric not even be touching the 1" Linacoustic and Cotton Batting?

Would should I purchase regarding the thickness of my Fabric Panels? 

a. 11/16 plywood (fabric panels) and 11/16" plywood (furring strips)?
b. 1/2 MDF (fabric panels) and 1/2 MDF (furring strips)?
c. 1/4 Plywood (furring strips) and 11/16" plywood (fabric panel)

Which combination considering the depth of the velcro and avoiding any bulging out of the 1" Linacoustic and Cotton Batting?


----------



## Brian Fineberg

so without reading this entire monster thread...

oc703 from floor to ear height
oc705 from ear height to ceiling

for all walls minus speaker wall?


----------



## erkq

Brian Fineberg said:


> so without reading this entire monster thread...
> 
> oc703 from floor to ear height
> oc705 from ear height to ceiling
> 
> for all walls minus speaker wall?


I'm not sure where you got that. I don't think I've seen that whole-wall coverage recommendation, ever. That would make for a very dead room. And you'd have no dispersion at all.

For example, *one *rule of thumb is 20% of room surface in absorption, 25% in dispersion.


----------



## Brian Fineberg

erkq said:


> I'm not sure where you got that. I don't think I've seen that whole-wall coverage recommendation, ever. That would make for a very dead room. And you'd have no dispersion at all.
> 
> For example, *one *rule of thumb is 20% of room surface in absorption, 25% in dispersion.


I've seen room designed with 705 as dispersion. The room I saw this is with the hidden in Bethesda build


----------



## jeeper114

*Where to get OC703 or 705 in larger sheets*

I need 7 sheets of OC703 or OC705 (or something equivalent to) in 1" X48" X 96". I see them everywhere as 24" X 48". Where can I get a larger sheet?


----------



## BllDo

You'll need to call around to local insulation suppliers. There's a place in the Twin Cities that sells it full sheets, so it's definitely available. Ask for rigid fiberglass insulation rather than a specific product name. If they are not an OC supplier, they might carry Johns Manville Insul-SHIELD. It's basically the same product.


----------



## erkq

Brian Fineberg said:


> I've seen room designed with 705 as dispersion. The room I saw this is with the hidden in Bethesda build


Really! Boy... I'd be interested in that! I'm trying to figure out how to make my dispersion panels in the easiest way. Curvy? Post-y? 4x4's? They're all so tedious to build and expensive to buy.


----------



## toofast68

erkq said:


> Really! Boy... I'd be interested in that! I'm trying to figure out how to make my dispersion panels in the easiest way. Curvy? Post-y? 4x4's? They're all so tedious to build and expensive to buy.


if you find this out, let me know as well


----------



## Brian Fineberg

how does this QuietR® Textile Duct Liner compare to linacoustic?


----------



## Jacob B

erkq said:


> Really! Boy... I'd be interested in that! I'm trying to figure out how to make my dispersion panels in the easiest way. Curvy? Post-y? 4x4's? They're all so tedious to build and expensive to buy.


GIK acoustics' *gridfusor *is one of the cheapest commercial diffusion products I have found. It's a 13-root QRD diffusor and you get 2' x 4' for 100 $. For that price, you either need to have loads of spare time on your hand, or work for 10-15 $ / hour, to make it worthwhile making your own...
They come in all colors, as long as you order a white ;-)

Cheers,
Jacob


----------



## myfipie

BllDo said:


> You'll need to call around to local insulation suppliers. There's a place in the Twin Cities that sells it full sheets, so it's definitely available. Ask for rigid fiberglass insulation rather than a specific product name. If they are not an OC supplier, they might carry Johns Manville Insul-SHIELD. It's basically the same product.


Correct on the Johns Manville. Just a note, even if you use 2'x4' panels you can still make a larger frame and use multiple panels inside. A bit more tricky but can be done.


----------



## toofast68

Jacob B said:


> GIK acoustics' *gridfusor *is one of the cheapest commercial diffusion products I have found. It's a 13-root QRD diffusor and you get 2' x 4' for 100 $. For that price, you either need to have loads of spare time on your hand, or work for 10-15 $ / hour, to make it worthwhile making your own...
> They come in all colors, as long as you order a white ;-)
> 
> Cheers,
> Jacob


Thanks for the info...this will help. Now I just gotta figure out if they will help me 


More work in REW to learn what I don't know


----------



## mtbdudex

Brian Fineberg said:


> so without reading this entire monster thread...
> 
> oc703 from floor to ear height
> oc705 from ear height to ceiling
> 
> for all walls minus speaker wall?





erkq said:


> I'm not sure where you got that. I don't think I've seen that whole-wall coverage recommendation, ever. That would make for a very dead room. And you'd have no dispersion at all.
> 
> For example, *one *rule of thumb is 20% of room surface in absorption, 25% in dispersion.


I've often said this thread should be locked and a new started for exactly this reason above.
Early posts here recommend 1" thick from the floor to 44" or so, then use cotton batting above 1" thick.
No way is that cookie cutter approach "S" scientific at all!

A new thread could be organized from scratch, with a good FAQ, etc.

Key relevant posts from this thread could be put into a new thread.


----------



## Al Sherwood

^^ I am glad someone else said it, I am designing a room now and the amount of conflicting information found here leads to a lot of questions and confusion. I know that there is no cookie cutter approach to this but I have to think that there are some general guidlines of do's and don'ts that would help one get started.

I know that for me with a AT screen the front wall treatments are different then someone with a TV screen or possibly a smaller screen where the speakerss are beside rather then behind... and on it goes.

When I start my actual build thread, I hope that some of the 'experts' from here will come take a peak and make suggestions!


----------



## raynist

I plan on lining my front wall with Linacoustic RC. I am going to use nails I think. Reading on the JM Site for the Linacoustic RC it looks like they recommend a sealer (superseal) any where you cut the insulation. Is everyone using this? Are there other options? Can the insulation be taped down on the wall where cuts are?


Thanks
Ray


----------



## BllDo

I think the issues with cuts is that the material may become airborne when used in a plenum or other air handling space. Used behind a screen wall and not directly in line with a ventilation system, should limit the possible exposure to whatever material may be come airborne. Sealing the cuts is probably not a bad idea, I don't know how necessary it absolutely is.

Edit: If you are going to use two layers with a layer of plastic between them (which is recommended) the first layer will effectively be sealed from the room. You could go an extra step and put some black speaker cloth or FR701 over the linacoustic to further limit the exposure to the room and reduce the light reflecting back from the nails or other fasteners. Just a thought.


----------



## Brian Fineberg

my "behind" screenwall is 10'9"x2'x7.5' would a 50' roll of linacoustic work?

I can get it on fabricmate.com for 160$

otherwise a 100' roll locally is 280$


----------



## raynist

Brian Fineberg said:


> my "behind" screenwall is 10'9"x2'x7.5' would a 50' roll of linacoustic work?
> 
> I can get it on fabricmate.com for 160$
> 
> otherwise a 100' roll locally is 280$


Seems like the math works for you. 

You would need 4 sections (assuming you are usng 2 inches) 10'9" long so you would have a bit left over. 

Only problem would be if some of it arrives damaged.


----------



## Brian Fineberg

is it recommended that you treat the side wall up to the screen?


----------



## Skrill

Hey guys -- anyone tried these Owens Corning absorbers? http://www.homedepot.com/p/Owens-Co...C-_-NavPLPHorizontal1_rr-_-NA-_-205212647-_-N

They somewhat cheap -- cheaper if you have a 10% off coupon -- with no shipping. Thinking of them only for secondary reflection points benefitting the back row seating positions (not for bass trapping or first reflection points).

I did a search on this product and found nothing.

Thanks!


----------



## coolgeek

Brian Fineberg said:


> is it recommended that you treat the side wall up to the screen?


There are basically 2 school of thought... one is where you treat the first reflection points, or, treat 20% of the room with absorbers, etc... 

After going through dozens of treated rooms (from expert intallers), i found one thing to be a constant.. almost all of them are over-treated and speakers sounded dead to me.. all the liveliness are gone!

So, when I designed my own HT room, i decided to only deaded the front stage (behind the LCR speakers). And I use perforated wood paneling for the ceiling (basically it has tiny perforated holes that allows some sound to get through and most will be reflected back (behind that I put in 4 inches of rockwool).

So, basically that's all the absorbers i have in my room that are 'exposed' to absorbing to high frequencies... everything else is designed as bass traps/dampeners... 

Of course, i can always ass 'absorbers' in my design and not mess up the interiors... and it turns out, i like the room with very little 'absorbers'.. remember, carpets are also absorbing... and other things in your room... 

All my side wall, back wall, etc treatments comprises diffusers instead... the room came out sounding lively and fantastic.. with just the right amount of reverb to make it sound like a much larger hall.. if i close my eyes, i can imagine being in an Imax theater...


----------



## KanosWRX

Skrill said:


> Hey guys -- anyone tried these Owens Corning absorbers? http://www.homedepot.com/p/Owens-Co...C-_-NavPLPHorizontal1_rr-_-NA-_-205212647-_-N
> 
> They somewhat cheap -- cheaper if you have a 10% off coupon -- with no shipping. Thinking of them only for secondary reflection points benefitting the back row seating positions (not for bass trapping or first reflection points).
> 
> I did a search on this product and found nothing.
> 
> Thanks!


Probably just OC703 behind some black fabric. At that price you could get 12 pannels of just 2'x4'x2" material, then buy your own speaker fabic and cover.


----------



## KanosWRX

Trying to find some 2" panels for treatments on my side walls, I found a local dealer that sells Johns Manville 2" Faced (on one side) material. I was wondering if this would be good to use on my walls for first reflection points and a couple other spots around the room. If I put the faced side against the drywall, would that essentially negate the effect of the facing material, making it like a normal unfaced piece? Would it be better to put the faced side facing toward the inside of the room? I would think that would reflect to much, so guessing no on that one. But really not sure if the facing on the backside touching the drywall would matter any?


----------



## Scurly

This acoustic treatment is brand new to me, so I hope to gain some starter knowledge. My media room is 19x13' - vaulted ceilings that travel upward from 7'8" (@ 45 degree angle) up to 10'. Floor is carpeted with 2 pieces if furniture.

There is an echo. 

I am looking for a start. No clue apart from reading way too much in the topic to be confused.

Should I put panels directly on the 45 deg angles? 2' x 4' x 2"? My thoughts: I have slots for 4 panels on the vaulted angles, 1 panel on the back wall and 2 or 4 panels on the side wall. So 9 total panels in all. 

I am not knowledgable enough to decipher what the room needs....only know where these panels "could" be hung. 

Are these panels easy to make? Seems stretching the fabric is tricky. What is recommended on the back side...1/4" plywood? Inside the panels obviously matters but don't want to spend arm and leg. 

Suggestions? Please keep it simple. Thanks


----------



## HopefulFred

Scurly said:


> There is an echo.


In small spaces, what's described as echo is usually properly called flutter echo. Flutter echo sounds like a "zing" sound added to the end of a staccato sound, such as a clap. It is caused by the repeated reflection of sound between two parallel surfaces, and is usually fairly easy to fix.

Since you have carpet, the floor and ceiling are not likely to be the pair of surfaces causing the problem. In stead, look to either the front and rear wall pair or the side walls. It could be both pairs.

As you begin to add treatment, do it in a way that allows the treatment to serve more than one function. To that end, I would start with the wall areas directly behind the front speakers. Adding a thick set of treatments there can help with flutter echo as well as correcting frequency response problems you may have due to SBIR. On the other hand, if you have been very careful or lucky, you may not have SBIR problems and it may make more sense to start with the rear wall. Either way, you shouldn't have to treat both walls of a pair to eliminate flutter echo - but you may want to for other reasons.

If the front/rear wall pair isn't the source of the flutter echo, it's probably the side walls. In that case, I would add treatment panels directly to the sides of the seats. These treatments should be symmetrical, but don't need to be large. So for a single seat or single row of seats, two 2' by 4' panels, 2" thick (though 4" would be better) should suffice.

For the technical details of how to build them, I would refer you to Mike's thread.http://www.avsforum.com/forum/19-dedicated-theater-design-construction/1312693-diy-construction-methods-hang-able-acoustic-panels-moveable-corner-traps-not-fixed-frames.html

As always, listen or measure carefully as you add treatments. Be aware of the changes you are making and how they are influencing what you hear.

Fred


----------



## Patrick Murphy

I would like to thank all the members here who contributed to this thread. After reading it and at other places (Gearslutz), I decided to get 6 OC 705 2" panels. I stood up 2 of them together and straddled them at the front corners with the bottoms on the floor and out 24" to the outside of the panels. The tops resting against the 2 walls. 


I used the mirror trick and found the 1st reflection points and set one panel on small foot tall boxes (temporary). Both of the panels are out from the walls at around four inches on the bottom and against the wall at the top. Just leaning as they are the naked panels with no framing. They are behind curtains on both sides.


I ran Audyssey XT32, turned on net radio and sat down to see the results.


Magical! It was as if I had never heard music before. The soundstage was wide and the instruments and vocals incredibly precise. Bass was much improved and more refined and articulate.


I have a nice system; 7.2 with all Polk RTi speakers, Onkyo 818 and Mitsubishi 7900 projector. I spent $150 for the panels and if somebody would have come in and set it up as I did and told me it would cost $750, I would have gladly paid it. Nothing I have ever added to the system has had anywhere near the impact of these panels.


Of course I immediately thought of getting more. Another 6 should do it. Add one each to the corners (6" total), one to the 1st reflection (4") and one for the 2nd reflection (2"). We'll see, as I am incredibly overwhelmed by the sound as is.


My thanks to all with your expertise on placement and the theory of setting up a small home theatre. Your information was invaluable to me.


----------



## KanosWRX

Patrick Murphy said:


> I spent $150 for the panels and if somebody would have come in and set it up as I did and told me it would cost $750, I would have gladly paid it. Nothing I have ever added to the system has had anywhere near the impact of these panels.


Not sure where you got your panels from, but 6 2'x4'x2" panels at $150 seems high, if its just the plain material. Not sure if you have seen this, but just in case you decide to purchase more (of course if you live outside the US, not sure how much shipping would be then). http://www.atsacoustics.com/item--Roxul-Rockboard-80-Case-of-6--RB80.html. I just ordered 12 Roxul Rockboard 60 panels from them, came out to about $150 bucks with shipping, I guess if you buy more you save a little on shipping.


----------



## Patrick Murphy

KanosWRX said:


> Not sure where you got your panels from, but 6 2'x4'x2" panels at $150 seems high, if its just the plain material. Not sure if you have seen this, but just in case you decide to purchase more (of course if you live outside the US, not sure how much shipping would be then). http://www.atsacoustics.com/item--Roxul-Rockboard-80-Case-of-6--RB80.html. I just ordered 12 Roxul Rockboard 60 panels from them, came out to about $150 bucks with shipping, I guess if you buy more you save a little on shipping.


 
Hi,


That's where I got them from. The panels were $119 then shipping of $18 and tax, as I live in the same state Illinois, $9. So pretty close to $150. Well worth it.


----------



## KanosWRX

Patrick Murphy said:


> Hi,
> 
> 
> That's where I got them from. The panels were $119 then shipping of $18 and tax, as I live in the same state Illinois, $9. So pretty close to $150. Well worth it.


Wait you bought a 6pack of Rockboard 80 for $119 (no tax or shipping)? I see it listed at $72 dollars for a 6 pack.


----------



## Patrick Murphy

KanosWRX said:


> Wait you bought a 6pack of Rockboard 80 for $119 (no tax or shipping)? I see it listed at $72 dollars for a 6 pack.



I bought a 6 pack of OC 705 and I paid tax and shipping


http://www.atsacoustics.com/item--Owens-Corning-705-2-inch-Case-of-6--1021.html


----------



## KanosWRX

Patrick Murphy said:


> I bought a 6 pack of OC 705 and I paid tax and shipping
> 
> 
> http://www.atsacoustics.com/item--Owens-Corning-705-2-inch-Case-of-6--1021.html


Oh sorry didn't realize you said OC705, my bad


----------



## Brian Fineberg

What's the difference between 703 and 705?


----------



## KanosWRX

Brian Fineberg said:


> What's the difference between 703 and 705?


I like to use this site to compare materials,

http://www.bobgolds.com/AbsorptionCoefficients.htm

I actually went with the rockboard as it had a higher low freq absorption level. From what I have read though, the hevier boards seem to be a little better at low freq. 705 is heavier the 703.


----------



## raynist

I have a question about treating behind my AT screen. 

I would like to do a baffle wall but that is unlikely to pass by the wife as it would be too permanent of a structure. 

The other thought I had is to use Roxul safe and sound everywhere behind my screen and cover every area flush with the speakers. Would this have the same result as a baffle wall?

Thanks
Ray


----------



## BasementBob

raynist said:


> The other thought I had is to use Roxul safe and sound everywhere behind my screen and cover every area flush with the speakers. Would this have the same result as a baffle wall?


- A baffle wall (drywall or 1 inch MDF wall, with holes for speakers, with the speaker face mounted flush with the room side wall surface) will get rid of one bunch of SBIR (Speaker Boundary Interference Response), and up to double the energy of low frequency sound from your speakers (because all of that energy, formerly pushed backward into the space behind a free standing tower speaker, is now all being driven forward in phase). The baffle wall will not effect echo or modal response against that wall. With stereo there is a perceptible improvement in clarity using this technique when done properly.
- A thick absorptive wall will also get rid of that same one bunch of SBIR, but will reduce the energy of the low frequency sound from your speakers. A thin absorptive wall will have a lesser effect on both. The absorptive wall will reduce echo and modal resonance against that wall, and will reduce the RT60-ish and the spaciousness of the sound in the room. (I tried this and haven't been happy with the results, but some of that is due to other factors beyond my control.) Also, if your speakers are the wrong distance from your AT screen, an absorptive wall may take care of some of the reflection off the AT screen.
- In either case, the energy balance by frequency of the speakers will change from their intended design response, and will have to be equalized to compensate/restore -- unless the speakers were designed for these mounts (lots of baffle or wall-surface-mount speakers out there)


----------



## raynist

BasementBob said:


> - A baffle wall (drywall or 1 inch MDF wall, with holes for speakers, with the speaker face mounted flush with the room side wall surface) will get rid of one bunch of SBIR (Speaker Boundary Interference Response), and up to double the energy of low frequency sound from your speakers (because all of that energy, formerly pushed backward into the space behind a free standing tower speaker, is now all being driven forward in phase). The baffle wall will not effect echo or modal response against that wall. With stereo there is a perceptible improvement in clarity using this technique when done properly.
> - A thick absorptive wall will also get rid of that same one bunch of SBIR, but will reduce the energy of the low frequency sound from your speakers. A thin absorptive wall will have a lesser effect on both. The absorptive wall will reduce echo and modal resonance against that wall, and will reduce the RT60-ish and the spaciousness of the sound in the room. (I tried this and haven't been happy with the results, but some of that is due to other factors beyond my control.) Also, if your speakers are the wrong distance from your AT screen, an absorptive wall may take care of some of the reflection off the AT screen.
> - In either case, the energy balance by frequency of the speakers will change from their intended design response, and will have to be equalized to compensate/restore -- unless the speakers were designed for these mounts (lots of baffle or wall-surface-mount speakers out there)


Thanks. 

So with the Roxul I will loose bass/midbass as compared to no treatment at all?


----------



## Scurly

HopefulFred said:


> In small spaces, what's described as echo is usually properly called flutter echo. Flutter echo sounds like a "zing" sound added to the end of a staccato sound, such as a clap. It is caused by the repeated reflection of sound between two parallel surfaces, and is usually fairly easy to fix.
> 
> Since you have carpet, the floor and ceiling are not likely to be the pair of surfaces causing the problem. In stead, look to either the front and rear wall pair or the side walls. It could be both pairs.
> 
> As you begin to add treatment, do it in a way that allows the treatment to serve more than one function. To that end, I would start with the wall areas directly behind the front speakers. Adding a thick set of treatments there can help with flutter echo as well as correcting frequency response problems you may have due to SBIR. On the other hand, if you have been very careful or lucky, you may not have SBIR problems and it may make more sense to start with the rear wall. Either way, you shouldn't have to treat both walls of a pair to eliminate flutter echo - but you may want to for other reasons.
> 
> If the front/rear wall pair isn't the source of the flutter echo, it's probably the side walls. In that case, I would add treatment panels directly to the sides of the seats. These treatments should be symmetrical, but don't need to be large. So for a single seat or single row of seats, two 2' by 4' panels, 2" thick (though 4" would be better) should suffice.
> 
> For the technical details of how to build them, I would refer you to Mike's thread.http://www.avsforum.com/forum/19-de...s-moveable-corner-traps-not-fixed-frames.html
> 
> As always, listen or measure carefully as you add treatments. Be aware of the changes you are making and how they are influencing what you hear.
> 
> Fred


Fred: thank you for the input. Very much appreciated. 

I will start with the side walls with 2 panels each. My screen wall where the front speakers are located do not provide much room for panels behind them.... Only 18" wide. 

What about the vaulted walls?. Logic tells me this is where the odd reflections are coming from...however, I know no logic when it comes to this aspect of home theater. 

Oc703 (2") appears to be relatively inexpensive with wood and the fabric, this shound not be too expensive. Thanks again.


----------



## Mike Butny

Brian Fineberg said:


> What's the difference between 703 and 705?



http://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html

Selecting the Right Acoustic Material
We stock a variety of acoustic materials to make sure whatever your project calls for is readily available. All these materials are good sound absorbers, but there are some differences. Here's how these materials stack up.

Product Name	Density
lbs/ft3	125 Hz.	500 Hz.	1000 Hz.	4000 Hz.	NRC	Rigidity	Price/sq.ft.
Roxul AFB 2"	2.5 lb.	0.28	1.09	1.09	1.07	0.95	Flexible	$0.75
Plus: Excellent sound absorption, low cost. Best choice when strength and rigidity are not needed. Minus: Flexible like a batt or blanket. Not a problem if supported by a frame, fabric, etc.
Roxul Rockboard 60	6 lb.	0.32	1.06	1.02	1.04	0.95	Rigid	$1.08
Plus: Excellent sound absorption. Lower cost than 703 and 705. Good strength and rigidity. Best choice for an effective, affordable, rigid product. Minus: More expensive than AFB if you don't need a rigid material.
Roxul Rockboard 80	8 lb.	0.43	0.90	0.97	1.00	0.90	Rigid	$1.50
Plus: Excellent low freq sound absorption. Lower cost than 705. Good strength and rigidity. Minus: Does not absorb mid to high frequencies quite as well as Rockboard 60.
ATS Acoustics Rigid Fiberglass Board 1"	3 lb.	0.06	0.75	0.99	1.02	0.75	Rigid	$0.98
Plus: An exact substitute for 703 at a better price. Minus: You get more sound absorption from a 2-inch material.
ATS Acoustics Rigid Fiberglass Board 2"	3 lb.	0.29	1.11	1.13	1.03	1.00	Rigid	$1.33
Plus: An exact substitute for 703 at a better price. Minus: A little more expensive than AFB and Rockboard 60 for the same sound absorption.
Knauf ECOSE® 1" 3lb	3 lb.	0.08	0.62	0.88	0.99	0.65	Rigid	$1.02
Plus: A more eco-friendly, formaldehyde-free substitute for 703 at a similar price.
Knauf ECOSE® 2" 3lb	3 lb.	0.29	1.11	1.13	1.03	1.00	Rigid	$1.44
Plus: An eco-friendly, formaldehyde-free sustainable insulation board. Similar to Owens Corning 703 insulation.
Knauf ECOSE® 2" 6lb	6 lb.	0.32	1.08	1.06	1.04	1.00	Rigid	$2.48
Plus: An eco-friendly, formaldehyde-free sustainable insulation board. Similar to Owens Corning 705 insulation.
Knauf ECOSE® Black Acoustical Board 2"	6 lb.	0.33	1.07	1.07	1.06	0.95	Rigid	$2.92
Plus: An eco-friendly, formaldehyde free sustainable insulation board. Designed as an acoustical/visual barrier for wall and ceilings where black surface is required.
Owens-Corning 703 4"	3 lb.	0.84	1.24	1.08	0.97	1.15	Rigid	$3.29
Plus: Good low frequency absoroption, strong and rigid. Minus: More expensive than two layers of Rockboard or AFB.
Owens-Corning 703 2"	3 lb.	0.17	1.14	1.07	0.98	1.00	Rigid	$1.40
Plus: Well known product. Good for small projects where cost is not a big concern. Minus: More expensive than AFB and Rockboard 60 for the same sound absorption.
Owens-Corning 703 1"	3 lb.	0.11	0.68	0.90	0.96	0.70	Rigid	$0.97
Plus: Familar brand name, moderate strength and rigidity. Minus: High cost, lower sound absorption (NRC) because it is only 1" thick.
Owens-Corning 705 2"	6 lb.	0.16	1.02	1.01	0.99	0.95	Rigid	$2.48
Plus: Strongest surface resists damage (like stiff styrofoam). Minus: Expensive. Rockboard 60 is usually a better choice.
Owens-Corning 705 1"	6 lb.	0.02	0.63	0.85	0.95	0.65	Rigid	$1.69
Plus: Familar brand name, good strength and rigidity. Minus: High cost, lower NRC because it is only 1" thick.
Applegate Recycled Cotton 2"	2.5 lb.	0.27	1.17	1.15	1.06	1.05	Flexible	$1.54
Plus: Excellent sound absorption. High recycled content makes it the most eco-friendly choice. Minus: Flexible like a batt or blanket. Not a problem if supported by a frame, fabric, etc.
Owens-Corning 703 FRK 2"	3 lb.	0.63	0.95	0.79	0.35	0.75	Rigid	$2.38
Plus: Excellent sound absorption. Most popular material for acoustic absorption. Minus: The cost is higher that other insulation products, and some high-end frequencies will be reflected.
Sound absorption coefficients are measured with the material in Type A mounting, flat against a solid backing. Bass absorption may be enhanced using corner mounting or increasing thickness with additional layers of material.

Our ready-to-hang ATS Acoustic panels are built using the 2.5 lb/ft3 Roxul AFB, for solid broadband absorption in Type A mounting at an exceptional price. Roxul's AFB is also known for exceptional fire characteristics and resistance to sag over time.


----------



## BasementBob

Mike Butny said:


> http://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html
> 
> ...
> Owens-Corning 703 FRK 2
> Most popular material for acoustic absorption. ... some high-end frequencies will be reflected.


I hope FRK is not the most popular -- it shouldn't be. The uncertainty is a mess. The membrane will do something. What it will do in any given room is unknown. 
The high end frequencies reflection depends upon if the foil is facing the center of the room, or facing the wall.


----------



## toofast68

I just figured I would post what I made...thanks to a bunch of members for all the ideas.


I have an odd shaped open concept dedicated theater. Based on some REW testing and reading I decided to make 3 Bass Traps with a bit of diffusion (at least I think I was able to do this)


I have 3.5" of Roxul with 3" of air gap shaped in long/skinny traps. The 4" frames actually do a tad bit of diffusion for me, and the traps, although not your normal placement, do help quite a bit. This in conjunction with my ceiling cloud (that is almost installed) took an odd theater layout and made it quite nice sounding (and on a budget as well)


----------



## Al Sherwood

raynist said:


> I have a question about treating behind my AT screen.
> 
> I would like to do a baffle wall but that is unlikely to pass by the wife as it would be too permanent of a structure.
> 
> The other thought I had is to use Roxul safe and sound everywhere behind my screen and cover every area flush with the speakers. Would this have the same result as a baffle wall?
> 
> Thanks
> Ray





BasementBob said:


> - A baffle wall (drywall or 1 inch MDF wall, with holes for speakers, with the speaker face mounted flush with the room side wall surface) will get rid of one bunch of SBIR (Speaker Boundary Interference Response), and up to double the energy of low frequency sound from your speakers (because all of that energy, formerly pushed backward into the space behind a free standing tower speaker, is now all being driven forward in phase). The baffle wall will not effect echo or modal response against that wall. With stereo there is a perceptible improvement in clarity using this technique when done properly.
> - A thick absorptive wall will also get rid of that same one bunch of SBIR, but will reduce the energy of the low frequency sound from your speakers. A thin absorptive wall will have a lesser effect on both. The absorptive wall will reduce echo and modal resonance against that wall, and will reduce the RT60-ish and the spaciousness of the sound in the room. (I tried this and haven't been happy with the results, but some of that is due to other factors beyond my control.) Also, if your speakers are the wrong distance from your AT screen, an absorptive wall may take care of some of the reflection off the AT screen.
> - In either case, the energy balance by frequency of the speakers will change from their intended design response, and will have to be equalized to compensate/restore -- unless the speakers were designed for these mounts (lots of baffle or wall-surface-mount speakers out there)



Since my tower speaker were not designed to be used in a baffle wall, I am leaning to simply treating the entire wall behind the AT screen as Ray is asking about, but with what and how thick? 


Also you mention the speaker distance from the AT screen, what is right or wrong here, I thought as close as practical would be the best choice?


----------



## Brian Fineberg

Anyone know the measurements of a roll of 100' of 1" linacoustic. I'm going to pick up a roll and want to know if it will fit. 

Thanks


----------



## asoofi1

Brian Fineberg said:


> Anyone know the measurements of a roll of 100' of 1" linacoustic. I'm going to pick up a roll and want to know if it will fit.
> 
> Thanks


46 1/4" tall


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## pkarakis

I just bought some. It is 48" wide.


Pete


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## KOSletten

....and about 27 to 28 inches in diameter.


KO


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## granroth

Brian Fineberg said:


> Anyone know the measurements of a roll of 100' of 1" linacoustic. I'm going to pick up a roll and want to know if it will fit.
> 
> Thanks


Some details here: http://www.avsforum.com/forum/19-de...an-100-roll-1-linacoustic-rc-fit-car-yes.html

And even more details here: The Elusive Linacoustic


----------



## asoofi1

granroth said:


> Some details here: http://www.avsforum.com/forum/19-de...an-100-roll-1-linacoustic-rc-fit-car-yes.html
> 
> And even more details here: The Elusive Linacoustic


Now the only measurement missing is the weight of that sucker.


----------



## granroth

asoofi1 said:


> Now the only measurement missing is the weight of that sucker.


Some small amount over 47 pounds.

I can't be precise for two reasons:

1. I already used maybe 15' or 20' of my roll, so it's not at full weight
2. My scale only works if somebody is stepping on it. So I had to measure it by holding it above my head like Atlas and then subtracting my weight. I might have shifted to one side or another during this, which can throw off the measurement by a few pounds.

All in all, assume around 50 pounds for any practical reasons.


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## Patrick Murphy

Patrick Murphy said:


> Of course I immediately thought of getting more. Another 6 should do it. Add one each to the corners (6" total), one to the 1st reflection (4") and one for the 2nd reflection (2"). We'll see, as I am incredibly overwhelmed by the sound as is.


Well that is exactly what I did and it certainly didn't blow me away like the first set of 6 did. The double thick panels at the 1st reflection point seemed to take away some highs and shrink the soundstage. The single panel at the 2nd reflection point didn't seem to do anything, but to be fair I likely should have put up 2 panels side by side as at the distance of 15 feet it was probably asking too much for a single panel to work. The addition of another 2 inches to the front corners (6 inches total) seemed to tighten up the bass even more so I'm happy about that. 

I also covered them in burlap fabric so they are not dispensing fibers into the air as far as I can tell.

This morning I made some changes. I took the double thick panels and moved them to the back corners and put the single panel back at the 1st reflection point. It sounds much better. Even though I didn't hear that much bass buildup in the back corners, I could hear some. Now I hear none. The 1st reflection point is back with an expanded soundstage and crisp clean highs. And I feel justified in purchasing these additional panels as there is now a considerable improvement. 

So now I'm done.


----------



## Eric van Ballegoie

Hi Guys,

This thread contains a wealth of information, but at nearly 11.000 posts, it has become almost impossible to find anything. Is there a FAQ of some sorts about the basics of theater design and acoustical treatments?

Apologies if I'm overlooking something, but I used to search funtion and came of empty handed.


----------



## adrian74

Eric van Ballegoie said:


> Hi Guys,
> 
> This thread contains a wealth of information, but at nearly 11.000 posts, it has become almost impossible to find anything. Is there a FAQ of some sorts about the basics of theater design and acoustical treatments?
> 
> Apologies if I'm overlooking something, but I used to search funtion and came of empty handed.


Don't worry you are not alone...I'm still trying to figure out what to do with my front wall.


----------



## Brian Fineberg

ive asked this a couple times in my thread but no answer...

behind my AT screenwall I have Linacoustic "sandwich" should I extend that on to the ceiling and side walls behind the screen?


----------



## nitro28

My understanding is you want the front wall 4" thick now vs the two layers of linacoustic that others use to do. Still a little confused on which insulation to use for the 4" though. I agree a consolidated thread with the 2015 recommendations would be helpful. I do realize this is a complicated subject and there are multiple ways to outfit a room.


----------



## KanosWRX

Brian Fineberg said:


> ive asked this a couple times in my thread but no answer...
> 
> behind my AT screenwall I have Linacoustic "sandwich" should I extend that on to the ceiling and side walls behind the screen?


It depends on the acoustics of your room, more then likely you don't need it there as the speakers are in front of those positions. First reflection points are ahead of the screen, not behind it. As long as you have corner bass traps you should be ok.


----------



## Al Sherwood

Brian Fineberg said:


> ive asked this a couple times in my thread but no answer...
> 
> behind my AT screenwall I have Linacoustic "sandwich" should I extend that on to the ceiling and side walls behind the screen?





KanosWRX said:


> It depends on the acoustics of your room, more then likely you don't need it there as the speakers are in front of those positions. First reflection points are ahead of the screen, not behind it. As long as you have corner bass traps you should be ok.



I am not an expert, but it is my understanding that there can be reflections off the back side of the screen that you want to tame, so treatment of the front wall may be advisable.


----------



## KanosWRX

Al Sherwood said:


> I am not an expert, but it is my understanding that there can be reflections off the back side of the screen that you want to tame, so treatment of the front wall may be advisable.


Front wall yes, but the little bits to the left and right and the ceiling behind the screen wall probably not a big deal, talking maybe a couple feet in each of those areas. I haven't seen anyone specifically talk about filling those any for acoustic treatments.. but who know maybe it helps some, but its probably minimal. Best to get the front and back walls and bass traps and first reflection points, then your at least 75% of the way there.


----------



## Brian Fineberg

KanosWRX said:


> Front wall yes, but the little bits to the left and right and the ceiling behind the screen wall probably not a big deal, talking maybe a couple feet in each of those areas. I haven't seen anyone specifically talk about filling those any for acoustic treatments.. but who know maybe it helps some, but its probably minimal. Best to get the front and back walls and bass traps and first reflection points, then your at least 75% of the way there.


My plan thus far is...the current 2" of Linacoustic behind the screen

Linacoustic filled fabric panels on rear wall
Linacoustic filled fabric panels on first reflection walls
empty Fabric panels the rest of the room...

first reflection on ceiling will be a future upgrade if needed.

Also Chunky bass traps in front corners behind screen


----------



## adrian74

I found this article today which at least for me provides an understandable starting point. http://carltonbale.com/home-theater-room-acoustic-design-tips/

Framing out panels with Corning 703 in them is what I was already thinking about which I think would be easier to cover with black fabric vs trying to secure it cleanly directly on the wall. I just wasn't sure what I should use inside the panels.

The question that this leads me to is what fabric material to use? Originally I was considering black duvetyn for it's low light reflectivity and cost vs velvet, but how well will that work if you are trying to utilize the acoustic fiberglass inside the panels? Other threads I've read about making acoustic panels talk about using a fabric that is acoustically transparent (ex. Guilford of Maine). So essentially I'm dealing somewhat with a contradiction. Go black/low LR front, ceiling,floor, at least close to the projector and yet deal with decreasing/removing sound reflections in the front, sides near speakers.

btw, my front wall is Drywall on the inside. Behind it is a storage room with the backside still open. So if there is anything I would want to put in the wall cavity before I close it up I'd like input on that as well.


----------



## Al Sherwood

adrian74 said:


> I found this article today which at least for me provides an understandable starting point. http://carltonbale.com/home-theater-room-acoustic-design-tips/
> 
> Framing out panels with Corning 703 in them is what I was already thinking about which I think would be easier to cover with black fabric vs trying to secure it cleanly directly on the wall. I just wasn't sure what I should use inside the panels.
> 
> The question that this leads me to is what fabric material to use? Originally I was considering black duvetyn for it's low light reflectivity and cost vs velvet, but how well will that work if you are trying to utilize the acoustic fiberglass inside the panels? Other threads I've read about making acoustic panels talk about using a fabric that is acoustically transparent (ex. Guilford of Maine). So essentially I'm dealing somewhat with a contradiction. Go black/low LR front, ceiling,floor, at least close to the projector and yet deal with decreasing/removing sound reflections in the front, sides near speakers.
> 
> btw, my front wall is Drywall on the inside. Behind it is a storage room with the backside still open. So if there is anything I would want to put in the wall cavity before I close it up I'd like input on that as well.


 
Seen that site before, good information there too. Always liked the look of the walls in his viewing room, but wondered if they might have too much treatment? He suggests 60-70% treated and that room is at 80%, I worry that it might end up too dead? 


My room will be primarily for multi-channel sound (actually Atmos), so I need to take care with the treatments.


----------



## Jacob B

Brian Fineberg said:


> My plan thus far is...the current 2" of Linacoustic behind the screen
> 
> Linacoustic filled fabric panels on rear wall
> Linacoustic filled fabric panels on first reflection walls
> empty Fabric panels the rest of the room...
> 
> first reflection on ceiling will be a future upgrade if needed.
> 
> Also Chunky bass traps in front corners behind screen


This has been the generel advice for the last 8 years at least in this thread, although the commercial experts tend to recommend what they sell, whether this is that every room is unique and requires a unique solution (those that sell such a service), or every room needs corner bass traps, side wall first reflection absorption panels, and front wall absorption treatment if using an AT screen (those that sell such standardized products). 
There is a certain degree of egg and hen situation, as acoustic companies started by acoustic experts with a past as HT designers and builders will come up with products they have experience in works in customerized installations.

However, I also see a tendency in lots of experience coming from music studio acoustics, and I am not so sure any more that all that experience is transferable 1:1 to home theater.

For instance, the corner broadband bass trap (studiotips super chunks) 'standard' recommendation might and might not be needed/preferable in a HT. An alternative is the use of four corner loaded subwoofers, combined with quality eq. Or even two front corner loaded, or one center front wall and one center rear wall.
Four corner loaded subs will minimize a lot of the room modes, but you will not lose all that general mid bass to broadband absorption.
Of course, SSC bass traps are a lot cheaper than dual or quatro subs, but definately not without its price.

Another arguement is that requirements for music mixing acoustics might be different from what is a pleasant and natural sound when listening to music and moviesoundtrack in a HT room.
The mixer needs a flat frequency response, but not necesarily "a natural" / live music sound. 

There is an acoustic school in HT that argues you should aim for what the mixer heard in the studio.

And there is a school that argues for less/no porouse absorption treatment and more diffusion (which often will have a degree of absorption due to turbulence and wave cancellation - or something like that  ) 

The latter school appreciates more lively rooms, as it resembles live music more. It also argues that we as humans are used to lively acoustics, despite its potential negative influence on dialogue clarity, etc., and that our brain therefor is used to compensating. Therefore, the argument goes, a flat frequency responsive but acoustically semi dead room will sound unnatural and actually stress our brain, making a longer stay in the room feel unpleasant - despite the perfect frequency response.

It is my argument that many of the rooms designed after the "code" in the beginning of this thread, i.e. 12 years ago, with one inch linacoustic or OC703 treatment on entire front wall and on side walls from front wall and 2/3 back, plus carpet, plus SSC corner traps, fall into this later description.

The first school would respond that it is the surround speakers that should create the ambience in a HT room, not 1st, 2nd, and tertiary reflections from the front speakers. 

The second school would argue back that if the room is also used for 2 CH music, as a lot of smaller HT rooms appear to be, then there are no surround speakers (turned on) and a compromise is required. 
A related arguement would be that even though surround speakers can create the lost (to absorption) rear hemisphere ambience, they cannot create the lost width of the front soundstage. You dont get the illussion of a wider-than-your-speakers concert stage or movie scene that high quality speakers can provide in a good 2 CH setup. 'Front wide speakers' actually try to recreate this lost ambience, but such speakers are not standard in most HT and have actually disappeared in DSU atmos upsampling. 
The depth of the front soundstage that might be hurt by placing absorption behind the front speakers cannot be recreated in any way.

Another arguement from the second school might be that by optimizing clarity for multiple row multiple seats HT (by treating so much of the side walls), you pay a high price for the sound experience at the 2 primary seats in many small HT, that might or might not be the only seats occupied in 80 % of the time. Instead, only place FR panels for the MLP, or place narrow strips of absorption and diffussion on the side walls. Bryan Pape was making such an arguement in the beginning of this thread - dualing with Dennis Erskine of school 1.

In sum, I definately believe this thread needs a status post, with a FAQ. 
As it is, I actually find it less than useful, and potentially harmful for users that 1) listen to 2 CH music as well as movies, 2) typically are less than four people in the HT (or less than four that worry about the finer details of acoustics), 3) design and build the HT based on 'common practice' from this thread without first hearing multiple rooms build with different acustical schools or paradigms in mind and 4) without having a room design so flexible that adding or removing acustical treatment based on the outcome of listening/testing/measuring sessions will not break or alter the visual design of the room in any negative way.

Cheers,
Jacob


----------



## LeBon

Brian Fineberg said:


> ive asked this a couple times in my thread but no answer...
> 
> behind my AT screenwall I have Linacoustic "sandwich" should I extend that on to the ceiling and side walls behind the screen?


Yes, Erskine specified covering the side and ceiling, as well as the front wall behind the screen. So I did that.


----------



## nvidio

adrian74 said:


> I found this article today which at least for me provides an understandable starting point. http://carltonbale.com/home-theater-room-acoustic-design-tips/
> 
> Framing out panels with Corning 703 in them is what I was already thinking about which I think would be easier to cover with black fabric vs trying to secure it cleanly directly on the wall. I just wasn't sure what I should use inside the panels.
> 
> The question that this leads me to is what fabric material to use? Originally I was considering black duvetyn for it's low light reflectivity and cost vs velvet, but how well will that work if you are trying to utilize the acoustic fiberglass inside the panels? Other threads I've read about making acoustic panels talk about using a fabric that is acoustically transparent (ex. Guilford of Maine). So essentially I'm dealing somewhat with a contradiction. Go black/low LR front, ceiling,floor, at least close to the projector and yet deal with decreasing/removing sound reflections in the front, sides near speakers.
> 
> btw, my front wall is Drywall on the inside. Behind it is a storage room with the backside still open. So if there is anything I would want to put in the wall cavity before I close it up I'd like input on that as well.


The fabric material has to be breatheable, i.e. if you put it close to your mouth and put your hand behind it you should be able to feel the air passing through it as you blow gently onto it. Guilford of Maine is a popular choice because it provides a clean look and finish, but it is relatively expensive. Personally, I, went for a black 100 percent polyester decorative fabric, but it is very thin so you can see the porous absorbing material (Knauf Insulation with ECOSE Technology) behind it. However, I fixed that problem by putting black 100 percent polyester wool batting (fleece plaid) between the decorative fabric and the Knauf. Polyester wool batting does an excellent job at preventing loose fibers from escaping, and it has sound absorption characteristics that are very similar to the layer of porous insulation material behind it. The layer of decorative fabric was not at all needed (nor harmful) in any way from an acoustics standpoint, but it sure did help to make the panels and bass traps look posh.


Oh and, BTW, here are a few interesting links to help people understand the basics about room acoustics:
http://arqen.com/acoustics-101/room-setup-speaker-placement
http://arqen.com/acoustics-101/speaker-placement-boundary-interference
http://arqen.com/acoustics-101/surround-sound-speaker-placement
http://arqen.com/acoustics-101/room-setup-acoustic-treatment
http://arqen.com/bass-traps-101/placement-guide


----------



## BasementBob

nvidio said:


> Guilford of Maine is a popular choice because it provides a clean look and finish, but it is relatively expensive.


Guilford of Maine is also fire resistant.


----------



## nvidio

BasementBob said:


> Guilford of Maine is also fire resistant.


Yes, but then so is polyester. As a matter of fact, Guilford of Maine *is* 100 percent polyester.


P.S. - Below is a close-up picture of the fabric that I use. The packet shown in that picture measures about 4" wide.


----------



## nvidio

In the book by _Rod Gervais_ titled _"Home Recording Studio: Build it Like the Pros"_, on page 207 you will find info on cloth covering for acoustic panels. (BTW, I googled for "guilford of maine fabric fire retardant", and page 207 of this book actually came up as the 3rd search result, it's on google books).


----------



## myfipie

> I found this article today which at least for me provides an understandable starting point. http://carltonbale.com/home-theater-...c-design-tips/


Some good tips in there but reading over it quickly there are a few things that are not correct.



> Fiberglass wall insulation is not dense enough. It’s designed to trap thermal air, not sound. It offers very little acoustic benefit because mid and lower frequencies pass right through it.


Actually if the panel or bass trap is over 6" thick less dense fiberglass will work better. 



> A home theater room needs to have about 60-70% of the surfaces covered in acoustic absorption material. To get the best acoustic performance, you’ll want about 60-70% of your walls and ceiling covered. However, you don’t want the room completely dead.


In a way I can agree with this but it is not just about the amount the proper treatment in the right spots.


----------



## bytebuster

Folks,
Wanted some tips on what I could do to improve the low frequency performance of the speaker on the right. I am assuming the speaker on the left has better low freq performance because of the adjoining sliding door and back wall

Any diffusers or absorbers I can use for this setup that will allow for a more balanced output from both speakers


----------



## HopefulFred

As a diagnostic move, shift everything left about two feet and listen again.

Probably the reflection off the short wall near the R loudspeaker is destructively interfering at your listening position. If that's the case, either a permanent relocation or significant absorption will help. The absorption would need to mostly fill the space between the short wall and the speaker.


----------



## AVSF458

Dennis Erskine said:


> Compromise between the two playback scenarios is not a good option. Effectively you're saying you're (a) willing to spend a bunch of money and (b) happy to make the room sound poorly in either case.
> 
> If you have a good surround processor and a well set up multi-channel room, play your 2 channel recordings in multi-channel mode...a better result. I can assure you a good surround processor will do a whole bunch better job of creating the spaciousness than your room can accomplish.


Would you consider the Denon 4520 CI as one of the better surround processors? The reason I ask is because of the room and limitations on placement of equipment my system sounds terrible compared to other similar set up except they have dedicated HT Room for the most part. Thanks.


----------



## bytebuster

HopefulFred said:


> Probably the reflection off the short wall near the R loudspeaker is destructively interfering at your listening position. If that's the case, either a permanent relocation or significant absorption will help. The absorption would need to mostly fill the space between the short wall and the speaker.


I am also thinking that the short wall is messing up the low frequencies.
I could try relocating things to the left. Though using this as a permanent solution isn't an option. Need to keep things centered with the projector screen.
Not sure if this matters but these are back ported speakers.

How would absorption behind this R speaker help though? I would have thought we would want to use some kind of reflector behind this speaker (or to its side) to better disperse the sound that may be escaping because of the short wall?
Or an absorber behind the left speaker to dampen the low frequencies?


----------



## HopefulFred

The fact that they are rear ported shouldn't make a difference unless you get really wild with the absorption and restrict airflow around the port.

The issue I'm speculating may be the problem is known as SBIR (Speaker Boundary Interference Response). The omnidirectional bass sound reflects from nearby boundaries and arrives at the listening position out of phase with the direct sound. The result is cancellation. The frequency of the cancellation is related to the distance between the speaker and the nearby surface. If the surface is farther than 3 feet or so, the frequency of the cancellation is low enough that the subwoofer has taken over and other room-related factors are dominating the response.

GIK acoustics has a very readable article about it here: http://www.gikacoustics.com/speaker-boundary-interference-response-sbir/

If this is, in fact, the reason for your problem, then adjusting position will be diagnostically significant even if you can keep it that way. The absorption could be effective by eliminating the reflected sound at the wall where it reflects - it can't be out of phase at the listening position if it never reflects.


----------



## bytebuster

Thanks HopefulFred. Let me play around with the placement of the speakers


----------



## myfipie

Hopefulfred is pretty dead on. You have build up and or SBIR problems off that short wall. You could try some bass trapping in that corner and see if it clears things up. It would be better to move but if you can, then that is that.


----------



## Steve Smith

What's the best practice for treating 1st reflection points on the ceiling? Most of the recommendations I see are for broadband treatment using 4" OC703 or similar with a 2-4" air gap. I did some testing by holding up a 2'x4'x4" OC703 panel wrapped in FR701 and measuring with REW using a CSL calibrated mic. The results were not what I expected. The full band (20-20khz) measurements showed the gain of the ceiling reflection was reduced by over 8db. The 20-500hz measurement showed no reduction in gain of the reflection. This would seem to indicate the frequencies being reflected are >500hz. 

Comparing the specs for 2" vs 4" OC703 shows the absorption coefficients at 500hz is only slightly better for 4". Above 500hz they are nearly identical. It would seem like 2" would be all that's needed in this case. Am I missing something here? 

From Bob Golds
OC703 2" 500hz 1.14
OC703 4" 500hz 1.24


----------



## Buckeye Dave

I am trying to determine if I can use black velvet to cover the entire screen wall (except the screen, obviously). For corner bass traps flanking each side of the screen, can I use black velvet to cover them and still expect them to adequately trap bass? My screen edges will butt right up to each corner trap so I am trying to eliminate light reflection.

If velvet is not good for covering a bass trap, what light-absorbing material would you suggest?


----------



## Ethan Winer

Bass easily passes through velvet into the bass trap, so that's fine.

--Ethan


----------



## Buckeye Dave

Ethan Winer said:


> Bass easily passes through velvet into the bass trap, so that's fine.
> 
> --Ethan


Thank you, Ethan!


----------



## PretzelFisch

I have a subwoofer in the front corner of my room and recently bought a gik tritrap to place in that corner. what are the trade offs between moving the sub out of the corner so the tritrap can sit on the floor vs being 23 inches inches up from the floor?


----------



## cogeng182

Could you guys help me out with pointing me to the technical reasons that broadband absorption on the front wall seems to be the newest convention for multichannel instead of the linacoustic and plastic sheet sandwich? Cant seem to find it in this monster thread.

I am ready to treat my front wall partly to improve sound, but also to block out light as I have a row of windows that stretches across the whole front wall. I have sourced a couple of options for linacoustic/knauf duct liner, best price I could find was $375 for one 100' roll. Is that a bad deal? Seems higher than what other people manage to find.


----------



## sdurani

cogeng182 said:


> Could you guys help me out with pointing me to the technical reasons that broadband absorption on the front wall seems to be the newest convention for multichannel instead of the linacoustic and plastic sheet sandwich?


Even in this day and age of multi-channel sound, the front soundstage still remains critical. That's where your attention will be focused, whether watching a movie or listening to music. With that in mind, seems reasonable to want to minimize sounds from that direction that could muddy up the front soundstage, like reflections from your surround speakers that are bouncing off the front wall.


----------



## HTPCat

^^ so are you saying that broadband absorption is better than linacoustic sandwhich for the front?


----------



## PrimeTime

Dennis Erskine said:


> If you have a good surround processor and a well set up multi-channel room, play your 2 channel recordings in multi-channel mode...a better result. I can assure you a good surround processor will do a whole bunch better job of creating the spaciousness than your room can accomplish.


Ah!

You be preachin' to my Amen Corner on this one.

This simple approach replaces thousands of posts on the subject.

Get the room acoustics out of the way and let modern DSP do its thing.


----------



## BamaDave

I need some advice please! I have just mounted some on ceiling speakers to support Atmos and I'm having some noticeable vibration that I want to mitigate, any suggestions? I did not think about this possibility when I mounted them so I have no dampaning in place between the speakers and the Sheetrock and the plywood on the other side I have them screwed to. I'm considering pulling them down and adding some rubber material (cut up soft rubber floor mats) between the speaker mounts and the ceiling, do you think this will help? Thanks! BD


----------



## KanosWRX

BamaDave said:


> I need some advice please! I have just mounted some on ceiling speakers to support Atmos and I'm having some noticeable vibration that I want to mitigate, any suggestions? I did not think about this possibility when I mounted them so I have no dampaning in place between the speakers and the Sheetrock and the plywood on the other side I have them screwed to. I'm considering pulling them down and adding some rubber material (cut up soft rubber floor mats) between the speaker mounts and the ceiling, do you think this will help? Thanks! BD


When building my HT I build boxes in the ceiling to support Atmos speakers in the future. To mount them to the joists I used 4 IB3 brackets. You might want to try those if you can. Not sure what kind of space you have though or how the speakers are mounted.


----------



## BamaDave

KanosWRX said:


> When building my HT I build boxes in the ceiling to support Atmos speakers in the future. To mount them to the joists I used 4 IB3 brackets. You might want to try those if you can. Not sure what kind of space you have though or how the speakers are mounted.


I have limited space and based on that I used pieces if plywood on the back side the screw the mounts to. So that is not really an option but thanks tho!


----------



## KanosWRX

BamaDave said:


> I have limited space and based on that I used pieces if plywood on the back side the screw the mounts to. So that is not really an option but thanks tho!


Darn, well maybe could use the rubber pieces from them? They are about 1/4" thick. Or like you said any other rubber piece would probably help too.


----------



## PretzelFisch

How important is it to start from the floor all the way to the ceiling with a corner bass trap what would happen if you start a foot up the wall?


----------



## nvidio

PretzelFisch said:


> How important is it to start from the floor all the way to the ceiling with a corner bass trap what would happen if you start a foot up the wall?





> Bass builds up more strongly in the corners of your room, and most strongly in trihedral corners (wall-wall-ceiling and wall-wall-floor intersections). Technically speaking, the variation of sound pressure for all frequencies is maximum in the trihedral corners.


Source: http://arqen.com/bass-traps-101/placement-guide


----------



## sdurani

HTPCat said:


> ^^ so are you saying that broadband absorption is better than linacoustic sandwhich for the front?


If you're going to absorb, then absorb broadband (unless you're using absorbers as a form of tone control to reduce higher frequencies).


----------



## myfipie

PretzelFisch said:


> How important is it to start from the floor all the way to the ceiling with a corner bass trap what would happen if you start a foot up the wall?


IMO it comes down to the more area you cover the better the response will be. Needless to say though starting with only half the corner is better then nothing, but you will notice a large improvement when the whole corner is covered floor to ceiling.


----------



## PretzelFisch

myfipie said:


> IMO it comes down to the more area you cover the better the response will be. Needless to say though starting with only half the corner is better then nothing, but you will notice a large improvement when the whole corner is covered floor to ceiling.


Thanks, I have the sub up against the two front corners of my room. So I am trying to figure out if i should pull them out enough so a tri trap fits behind it or on top of it. My current thinking is on top of sub up to the ceiling.


----------



## nitro28

I can get Thermafiber Ultrabatt mineral wool easily and cheap at menards in 2'x4' pieces. Am I ok using this for bass traps in triangles? I have read so much I am confused now. I know the pink fluffy stuff works, but seems like more work due to having to support it from being compressed. The triangles stacked from floor to ceiling seem pretty simple. I could order OC 703 but its pricey and Roxul has to be ordered to. Hoping this Thermafiber would work about the same. 17x17x34" triangles. Thanks.

http://www.menards.com/main/building-materials/insulation/rolls-batts/r-25-thermafiber-mineral-wool-insulation/p-2084145-c-5780.htm


----------



## myfipie

PretzelFisch said:


> Thanks, I have the sub up against the two front corners of my room. So I am trying to figure out if i should pull them out enough so a tri trap fits behind it or on top of it. My current thinking is on top of sub up to the ceiling.


I would try it both ways to see how it sounds. Keep in mind that you can also lay the Tri Traps across front wall along the wall if that fits better.


----------



## myfipie

nitro28 said:


> I can get Thermafiber Ultrabatt mineral wool easily and cheap at menards in 2'x4' pieces. Am I ok using this for bass traps in triangles? I have read so much I am confused now. I know the pink fluffy stuff works, but seems like more work due to having to support it from being compressed. The triangles stacked from floor to ceiling seem pretty simple. I could order OC 703 but its pricey and Roxul has to be ordered to. Hoping this Thermafiber would work about the same. 17x17x34" triangles. Thanks.
> 
> http://www.menards.com/main/building-materials/insulation/rolls-batts/r-25-thermafiber-mineral-wool-insulation/p-2084145-c-5780.htm


Never used the Thermafiber stuff but seems kind of like the knauf we sell that people do corners with. 
http://www.gikacoustics.com/product/knauf-rigid-fiberglass-1-6-lb/


----------



## nitro28

myfipie said:


> Never used the Thermafiber stuff but seems kind of like the knauf we sell that people do corners with.
> http://www.gikacoustics.com/product/knauf-rigid-fiberglass-1-6-lb/


Thanks, so in your opinion is there really much of a difference in any of the types of insulation for bass traps (i.e. OC 703, Pink Fluffy, Mineral wool etc. ) If its really more about thickness and placement I'll just go with this easy to find mineral wool. Thanks.


----------



## myfipie

nitro28 said:


> Thanks, so in your opinion is there really much of a difference in any of the types of insulation for bass traps (i.e. OC 703, Pink Fluffy, Mineral wool etc. ) If its really more about thickness and placement I'll just go with this easy to find mineral wool. Thanks.


That depends on the thickness. Generally speaking for absorption below 6" I would use 3 pound.. For filling the corner and or thicker panels I would use less dense.


----------



## emr25

I've been exchanging emails with GIK regarding my small HT room. I'd like to see what type of advice is offered here as well. The equipment is listed in my signature.

If you had to prioritize how you would treat the room shown in the linked image using GIK (or similar) products, where would you start? First priority, second, third, etc. Assume price is not a concern, although it will be (I'd like to spend ~$500 now and get the best improvement possible, with the potential to add more later).

Thanks in advance for the advice, room treatments are a relatively new concept for me, but I believe they are the next logical step in my room.

Edit: Added additional images for reference.


----------



## artur9

emr25 said:


> If you had to prioritize how you would treat the room shown in the linked image using GIK (or similar) products, where would you start?



You didn't say what you were hoping to achieve. Better dialogue clarity, improved imaging, improved bass, improved soundstage?

Eventually you can have all that but it's hard to prioritize without that piece of info.


----------



## emr25

artur9 said:


> emr25 said:
> 
> 
> 
> If you had to prioritize how you would treat the room shown in the linked image using GIK (or similar) products, where would you start?
> 
> 
> 
> 
> You didn't say what you were hoping to achieve. Better dialogue clarity, improved imaging, improved bass, improved soundstage?
> 
> Eventually you can have all that but it's hard to prioritize without that piece of info.
Click to expand...

Good point. I'm not sure to be honest, I guess I could say that I'm looking for more control at higher volumes. I do think the speakers I have are very clear and dynamic, even up to and beyond reference. But I know I am overpowering the space at times, so whatever that translates to (if anything at all!) is what I'm looking for.


----------



## HopefulFred

I'm going to guess that means your decay times are a little out of whack. That's common. The challenge (if true) is finding ways to bring it down in the ranges that need to be brought down. Chances are some commonly available bass traps are a good choice - like 244 bass traps or monster traps (to mention the GIK products, since you started with them).

Ethan Winer has always said (don't let me put words in his mouth, but I'm trying to paraphrase and capture the spirit of his remarks) that everyone needs bass traps and the more the better. I have always liked that advice.

When low frequency sound is allowed to persist too long (insufficient damping), the accentuated bass can overwhelm your sense of hearing and make other neighboring frequency ranges obscured. This can lead to speech intelligibility problems and bloated bass in music. So, that's what I suspect is happening when you turn up the volume.

Alternatively, you could try turning down the bass. Does that help, or just make you sad?


----------



## emr25

HopefulFred said:


> I'm going to guess that means your decay times are a little out of whack. That's common. The challenge (if true) is finding ways to bring it down in the ranges that need to be brought down. Chances are some commonly available bass traps are a good choice - like 244 bass traps or monster traps (to mention the GIK products, since you started with them).
> 
> Ethan Winer has always said (don't let me put words in his mouth, but I'm trying to paraphrase and capture the spirit of his remarks) that everyone needs bass traps and the more the better. I have always liked that advice.
> 
> When low frequency sound is allowed to persist too long (insufficient damping), the accentuated bass can overwhelm your sense of hearing and make other neighboring frequency ranges obscured. This can lead to speech intelligibility problems and bloated bass in music. So, that's what I suspect is happening when you turn up the volume.
> 
> Alternatively, you could try turning down the bass. Does that help, or just make you sad?


I went ahead and ordered (3) Monster Bass Traps (Range Limiter) and (2) 244 Bass Traps (Full Range). The MBTs will be positioned vertically on the rear wall. The 244s will be positioned vertically on the front wall behind the L/R speakers. All of the panels will be in the Guilford of Maine 408 Black fabric.

This should be a good start in improving the acoustics in the room, it seemed to be a trend (just as in your advice) that absorbing bass should be the first priority.

And to answer your last question, I am in a ~960 ft^3 suspended floor room with JTR Noesis 228HT mains and a JTR Captivator S2 subwoofer. I honestly don't go much above -8.0 dB MV very often for movies, but with that kind of capability it certainly gets cranked up on occasion!


----------



## nonstopdoc1

I am sure there is an answer to my question in these 361 pages but unfortunately I haven't been able to find it. It appears that most of the DIY builders here are covering their walls with absorber like linacoustic covered with fabric like GOM but the layout plans from professionals that are shared here on the forum have acoustic treatment plan mostly composed of acoustic panels.

Which one is more effective and which one is more economical for a dedicated HT??


----------



## nonstopdoc1

I am sure there is an answer to my question in these 361 pages but unfortunately I haven't been able to find it. It appears that most of the DIY builders here are covering their walls with absorber like linacoustic covered with fabric like GOM but the layout plans from professionals that are shared here on the forum have acoustic treatment plan mostly composed of acoustic panels.

Which one is more effective and which one is more economical for a dedicated HT??


----------



## HopefulFred

A complete system engineered by an experienced professional is almost always going to outperform a system put together by a DIYer using only absorption. The difference in price is probably in the 10x region, so there's the rub.

A competent and careful DIYer will probably find use for diffusion in a few places, and may need some iteration in practice to get everything as good as they can manage, so that closes the gap a little on the price difference, in some cases, but also on the performance gap as well.


----------



## KanosWRX

nonstopdoc1 said:


> I am sure there is an answer to my question in these 361 pages but unfortunately I haven't been able to find it. It appears that most of the DIY builders here are covering their walls with absorber like linacoustic covered with fabric like GOM but the layout plans from professionals that are shared here on the forum have acoustic treatment plan mostly composed of acoustic panels.
> 
> Which one is more effective and which one is more economical for a dedicated HT??


I think its also easier for companies to sell acoustic treatments if they are smaller. It's easier to sell a 2'x4' panel vs a roll of something that you have to put up and mount. That being said the goal from everything I have read is to not have your entire room covered in treatments, nor is it to just put up a few panels. It seems to be more of a even split, about 50% treatments, 50% bare, but its also about placement, like first reflection points. In my room my front and back walls are about 80-90% treated, then the sides about 50% (addressing first reflection points). The one thing I wish I could have done was a little more diffusion but with only about 2" of space between my dry wall and fabric system, diffusion wasn't going to help too much, so I did what little I could do, but mainly did absorption. In the end though it really comes down to two things, how picky you are about acoustics and how much money you have. If you have a ton of money, you pay someone to come out and acoustically tune your room. Otherwise you read what you can on the forums and try the best you can with what your room has to offer as well as your budget.


----------



## myfipie

KanosWRX said:


> I think its also easier for companies to sell acoustic treatments if they are smaller. It's easier to sell a 2'x4' panel vs a roll of something that you have to put up and mount. That being said the goal from everything I have read is to not have your entire room covered in treatments, nor is it to just put up a few panels. It seems to be more of a even split, about 50% treatments, 50% bare, but its also about placement, like first reflection points. In my room my front and back walls are about 80-90% treated, then the sides about 50% (addressing first reflection points). The one thing I wish I could have done was a little more diffusion but with only about 2" of space between my dry wall and fabric system, diffusion wasn't going to help too much, so I did what little I could do, but mainly did absorption. In the end though it really comes down to two things, how picky you are about acoustics and how much money you have. If you have a ton of money, you pay someone to come out and acoustically tune your room. Otherwise you read what you can on the forums and try the best you can with what your room has to offer as well as your budget.


Agree but also disagree a bit. For a professional room, which we do A LOT of we can cover almost all wall/ceiling surfaces with either absorption (tuned and or broadband) or diffusion. The trick is figuring out what areas can benefit the most from either and using the right type. Needless to say you are a 100% correct that addressing things like first/early reflection points, bass trapping in corners and thick absorption for the back wall is the first line of defense. Actually just being set up correctly in the room can make a world of difference. 
http://www.gikacoustics.com/basics-room-setup-acoustic-panels-bass-traps/


----------



## Aliens

This is not the actual product, just for reference. The local building supply has the CertainTeed, R-11 Soundshield. Comes in 2'X8'X3 1/2" strips (16 total). Not referenced on Bob Golds site. Great price @ $87. I know to remove the backing; will this be acceptable for making panels? I'm trying to avoid the high shipping costs of other products.


----------



## cgott42

Here are some pics (front and back) of my HT
Back:










Front:








My current acoustic treatment consists of :
3 GIK 244 Bass TGraps (burdendy) panels on each side wall - measured via mirror to 3 front speakers
2 Black DIY panels behind each front speaker - 4" thick , 2'x2' (not sure as I got it from an AVS'er)- they don't go all the way to the ground, nor to the ceiling (the black thing above it is just a 2 dimensional façade (hiding the projector) behind it is about 1 foot+ of space to the ceiling
5 Black DIY panels (same as above) on back wall- 1 smack center (next to desk), 2 vertical to the right of that, +1 to the right of that, + 1 to the right of that, on the floor in the corner

Approx. Room Dimensions 22x14x6.5' heightw, ith a soffit front to back along the left (About 1' from the side wall)
Of course I'd like everything, but my #1 priority is dialogue clarity (*currently not great*)
My Speaker setup: Goldenear Triton 2's (*with built in subs*) Goldenear SuperCenter XL, DefTech 8080st surrounds, GoldenEar SS 50C (rear), w/*SVS 20-39 pci powered sub*

What do you recommend that I do to rearrange what I got , or supplement it.
thx!


----------



## toofast68

your center clarity issue might be related to a strong ceiling 1st reflection...do you have REW or anything to verify this ?


If not, you can put something up temp and see if it makes a difference.


My ceiling cloud was night and day for me.


----------



## cgott42

Do you have a link to a ceiling cloud to buy or make. also I have low ceilings, so I can't have something hanging low
Thx


----------



## toofast68

Yes I made them but depending upon how low your ceiling is they may or may not work I will find the link and post it tomorrow they may or may not work I will find the link and post it tomorrow


----------



## Boomassiv

Anyone have some pictures of 4x8 panels they use? I want to make at least one for my back wall 2x2" with 703 I have. I have just been looking for some odd size panel builds (other than 2x4) as I will be using some.


----------



## ps24eva

Can someone explain what I can stuff behind drywall for acoustic treatment?

Most of this thread is about making panels.


----------



## HopefulFred

Anything you put on the far side of drywall will have no (real) impact on the acoustics of your room. Perhaps you're thinking about soundproofing? There is a separate thread for that.


----------



## ps24eva

HopefulFred said:


> Anything you put on the far side of drywall will have no (real) impact on the acoustics of your room.


Isn't the real intended purpose of Roxul Rockboard to go behind the wall?


----------



## KanosWRX

ps24eva said:


> Isn't the real intended purpose of Roxul Rockboard to go behind the wall?


Rockboard is actually more commonly used for acoustic treatments, like OC703. Roxul does sell other lighter density materials used for in wall insulation and sound proofing as well though. I have 2" Rockboard pannels in my room for first reflection point absorption and throughout other places as well inside my room.


----------



## nickbuol

Yup. Soundproofing does not equal acoustical treatments, however you can get great benefits from a decent effort in soundproofing a room. Not just to keep sound in, but to keep other sounds out. Still not acoustically treating the room though.


----------



## myfipie

cgott42 said:


> Do you have a link to a ceiling cloud to buy or make. also I have low ceilings, so I can't have something hanging low
> Thx


Since you have our products, most of our customers use something like attached. Though it does put a 4" gap (recommend) between the panel and the ceiling.
http://www.gikacoustics.com/product/acoustic-panel-ceiling-cloud-mounting-brackets/


----------



## prven

*Complaint from neighbor*

I recently did setup my 7.2 home theater system and unfortunately there is a window(8x4) in the center of the media room wall. Our neighbor's master bedroom is across that window and they are complaining that they are hearing a lot of noise in their bedroom.

I have been searching for ways to somehow eliminate the sound going out the window. Can someone please share what is the economical way of getting the sound arrested going outside through the window? Does a good set of curtains help?

I am newbie to this whole home theater experience so please help me with your suggestions.

Thanks!


----------



## Brucemck2

Prven: 
http://www.soundproofwindows.com/


----------



## asarose247

hAS ANYONE ANY EXPERIENCE/INPUT/USAGE OF THIS?
Murano Home Furnishing, FOAM FOR SOUND CONTROL,
ACOUSTIC WEDGES 1" OR 2" HEIGHT?, 12 X 12"


----------



## asarose247

hAS ANYONE ANY EXPERIENCE/INPUT/USAGE OF THIS?
Murano Home Furnishing, FOAM FOR SOUND CONTROL,
ACOUSTIC WEDGES 1" OR 2" HEIGHT?, 12 X 12"


----------



## myfipie

asarose247 said:


> hAS ANYONE ANY EXPERIENCE/INPUT/USAGE OF THIS?
> Murano Home Furnishing, FOAM FOR SOUND CONTROL,
> ACOUSTIC WEDGES 1" OR 2" HEIGHT?, 12 X 12"


Generally speaking foam is not going to do much below 500hz or so. Basically sucking up the upper frequencies but still leaving the mids and low end bouncing around. The goal is to have as even of absorption across the board as possible. 
http://www.gikacoustics.com/comparing-foam-to-gik-244-bass-traps/


----------



## asarose247

The entrance to my home hall way is 4 x 12 x 8 hi and there is a 44" wide passage to the LR where most of the stuff in my sig is . . 
That hallway is all hard and all parallel surfaces and maybe a world class site for being able to demo clap/flutter echo
after viewing a number of you tube vids, of all types, yep! you got flutter and its very pronounced . . while standing in that hallway

I want to minimize its effect wrt being some sort of adjacent echo chamber for the main room, 
i really can't begin to evaluate and/or quantify its overall contribution to sound degradation wrt MLP, which is about 15' away
the bass build up there is "impressive" and that just can't be good for LF overall (entire LR + attached spaces are close to 5K^3)
I don't expect to kill every problem this small space creates, but it could be a start
so my intent wrt to the foam wedges was to significantly dampen flutter

I could also build some SnS 3" panels 15 x 47 or 23.5 x 60 or any geometry staggered in that hall way set off the wall by 3" (extended french cleats)
I use sheer curtain material, primarily black and dark red for my covers, being AT, and the decorative/artistic "look" can be eclectic , 
I have ZERO WAF so if I like it , and it works, mostly, it's good

and then there is the evaluation and attack for what problems i undoubtedly have in my main listening area but i waiting to finish 2 more subs before I enter that branch of the rabbit hole
In the meantime, Audussey and the inukle makes for a good ATMOS/DSU environment

so if I ask, wedges or panels? I expect words about both and then there is someone who will say try it and get back to us, and some will say both, why not
constructive input appreciated

thank you


----------



## ahmedreda

My room is 12x20x8 and is covered with 1" thick panels. Some of the panels have oc703. 
My current plan is to raise some of the panels at the first reflection points of my lcr speakers. Would raising them to 3" while filling the first reflection points with 3" of oc703 be enough. I can't go 4" but I may be able to stretch it to 3.5". The later option would require me to slice a sheet of a 1" oc703 into 2 halves..

I am also planning later to take some of the drywall out off the ceiling and insert more oc703 at the first reflection points then seal it with black fabric. This way I don't have panels hanging off my low ceiling. 

I have no plans for the back side of my room. Any suggestions regarding that part would be appreciated.. I want to keep the room sounding live... Would leaving the back with no treatments be a good solution?

This is a picture showing the panels I currently have. I have more picture in my theatre upgrade thread in my signature.


----------



## asoofi1

ahmedreda said:


> My room is 12x20x8 and is covered with 1" thick panels. Some of the panels have oc703.
> My current plan is to raise some of the panels at the first reflection points of my lcr speakers. Would raising them to 3" while filling the first reflection points with 3" of oc703 be enough. I can't go 4" but I may be able to stretch it to 3.5". The later option would require me to slice a sheet of a 1" oc703 into 2 halves..
> 
> I am also planning later to take some of the drywall out off the ceiling and insert more oc703 at the first reflection points then seal it with black fabric. This way I don't have panels hanging off my low ceiling.
> 
> I have no plans for the back side of my room. Any suggestions regarding that part would be appreciated.. I want to keep the room sounding live... Would leaving the back with no treatments be a good solution?
> 
> This is a picture showing the panels I currently have. I have more picture in my theatre upgrade thread in my signature.


As a start, you could deaden the front of the room by placing a Linacoustic 'sandwich' (1" LA, layer of 4ml plastic, 1" LA) on entire front wall...and have absorbtion panels on just first reflection points on side walls and ceiling....personally, I would also place a pair of absorbers on the sides of your seating row to reduce back and forth reflections directly at ear...imagine a ping pong hitting back and forth hundreds of times per second and your sitting right between that chaos.

Some love the dead front and live back treatment plan...all depends on your room of course.


----------



## ahmedreda

I was planning on making panels behind each speaker (3" oc703) and stuff 6" in the corners.. Would the linacoustic have advantage over that? I think I am going to have to order extra oc703 so I am open to either material..



asoofi1 said:


> As a start, you could deaden the front of the room by placing a Linacoustic 'sandwich' (1" LA, layer of 4ml plastic, 1" LA) on entire front wall...and have absorbtion panels on just first reflection points on side walls and ceiling....personally, I would also place a pair of absorbers on the sides of your seating row to reduce back and forth reflections directly at ear...imagine a ping pong hitting back and forth hundreds of times per second and your sitting right between that chaos.
> 
> Some love the dead front and live back treatment plan...all depends on your room of course.


----------



## LoudDad

ahmedreda said:


> I was planning on making panels behind each speaker (3" oc703) and stuff 6" in the corners.. Would the linacoustic have advantage over that? I think I am going to have to order extra oc703 so I am open to either material..


What are your issues with your current setup?
Just wondering what you're trying to achieve.
If you are having specific problems it will be easier to give advice.


----------



## ahmedreda

My current setup only has 1" absorbers which don't do much for mid/low frequencies.
As a result my decay times were high when I measured them using REW. 
I am not looking to do anything regarding subwoofer frequencies (


----------



## artur9

ahmedreda said:


> My current setup only has 1" absorbers which don't do much for mid/low frequencies.


Would it be possible for you to put an air gap behind your current absorbers? Since you can measure, you could try that and see if it helps enough.


----------



## LoudDad

ahmedreda said:


> My current setup only has 1" absorbers which don't do much for mid/low frequencies.
> As a result my decay times were high when I measured them using REW.
> I am not looking to do anything regarding subwoofer frequencies (


----------



## DonnyKerabatsos

Looking for acoustic treatment advice on a room we are building in an addition to our home. I'm sure this has been covered, but the search function a thread this size is borderline useless, and I read a fair bit of conflicting info. 

The room unfortunately won't be a dedicated listening room, but I want to do as much as I can to optimize it for 2 channel listening (though it will have a 5.1 HT setup). The current design has the room as 17'x15'10". I think WAF may somewhat limit room treatments, though I will be abel to put some in, and have pretty wide latitude in speaker placement. Also, unlike my current listening space/living room, this will have thick carpet and be closed off from other areas of the house. Not sure yet if the ceiling will be vaulted or a tray, but will be at least 9 feet. If vaulted/lofted, it will be at its lowest point on the wall with the TV/front speakers, sloping up from there. 

Thoughts on whether the room dimensions listed are such that they should be tweaked? 

Any other advice for a room build I may not have found in my research (planning on prewiring for surrounds; less sure of how to prewire if we wanted to install a projector down the road). Also prewiring to allow outdoor speakers to be controlled from the avr.

My understanding is that using the formula f=1130/2d, The main room modes will be at 33.23 hz (length), 37.66 hz (width) and 56.50 hz for height, so my main focus should be bass traps in the rear corners. I read about the mirror test to place panels for minimizing first reflections at the listening position. Any other suggestions, are my priorities in the right order, and any acoustic treatment for dummies resources you can point me to?


FWIW, Speakers are NHT absolute towers up front, with a 2C center, and Def Tech PM800s for surrounds (for now at least). Currently have a Def Tech ProSub 1000 that is the next upgrade. Denon 1913 AVR.

Thanks in advance.


----------



## Patrick Murphy

You might be interested in this room mode calculator for setting up your speakers first. 








http://www.harman.com/EN-US/OurCompany/Innovation/Pages/Calculators.aspx?CategoryID=Calculators


----------



## skip61

*Living room*

Hi guys, i have a living room that i want to install acoustic panel to it. The size of the living room is 17' x 14' x 8' it has windows and a door behind the ht and opposite to the ht there is an entrance of 4' wide by 7' high. What type of panels should i use ? 
I live in an apartment so the living room was already finished.


----------



## DonnyKerabatsos

Patrick Murphy said:


> You might be interested in this room mode calculator for setting up your speakers first.
> 
> 
> 
> 
> 
> 
> 
> 
> http://www.harman.com/EN-US/OurCompany/Innovation/Pages/Calculators.aspx?CategoryID=Calculators


Thanks. I'm not able to use the Excel calculator (mac ecosystem) and the other one seems a bit complicated for my purposes, but I will try to learn a bit more so that I can put it to use.

I took a stab at doing a mock up of the room lay out, if that could yield any additional advice. (the media center will probably be narrower than what is in the mock up, with the FL and FR speakers out from the wall and inside of the windows on the left wall. I'll do a sub crawl for SW placement, and the surround speakers will likely have to be just behind the sets of double doors, which should put them just at 20 degree behind the MLP in the center of the couch).

Thanks again.

EDIT: I looked at my plans again, and there is supposed to be a double window basically behind the loveseat, which I inadvertently omitted form the mock up.


----------



## myfipie

> My understanding is that using the formula f=1130/2d, The main room modes will be at 33.23 hz (length), 37.66 hz (width) and 56.50 hz for height, so my main focus should be bass traps in the rear corners. I read about the mirror test to place panels for minimizing first reflections at the listening position. Any other suggestions, are my priorities in the right order, and any acoustic treatment for dummies resources you can point me to?


You are pretty much thinking in the right direction. 33hz is going to be pretty hard to tame but 66hz and above should be achievable with the right kind of bass trapping (basically as thick as you can stand) and covering as much corner area as you can. The only other thing I would add is THICK absorption on the back wall (this is the wall behind where you sit). The following article will give you a most of the answers for the set up.
http://www.gikacoustics.com/basics-room-setup-acoustic-panels-bass-traps/


----------



## myfipie

> My understanding is that using the formula f=1130/2d, The main room modes will be at 33.23 hz (length), 37.66 hz (width) and 56.50 hz for height, so my main focus should be bass traps in the rear corners. I read about the mirror test to place panels for minimizing first reflections at the listening position. Any other suggestions, are my priorities in the right order, and any acoustic treatment for dummies resources you can point me to?


You are pretty much thinking in the right direction. 33hz is going to be pretty hard to tame but 66hz and above should be achievable with the right kind of bass trapping (basically as thick as you can stand) and covering as much corner area as you can. The only other thing I would add is THICK absorption on the back wall (this is the wall behind where you sit). The following article will give you a most of the answers for the set up.
http://www.gikacoustics.com/basics-room-setup-acoustic-panels-bass-traps/


----------



## asarose247

a general question wrt sizes of treatments

other than the fact of actual physical sizes of variously available materials to work with, 
which tends to cause builders , in general it seems, to gravitate to "not thinking "outsized" the box" when constructing,
given the possibility of making it any size that fits or can be fitted, 
except for the chance to make a space too dead, 
any reason to not go big, 4' x 6' ,3" deep and 3" off the wall. for example
or could 6 of 2 x 2 maybe spread out produce a "better " result

any data or testing to illustrate real scientific differences?

curious


----------



## BasementBob

asarose247 said:


> any reason to not go big, 4' x 6' ,3" deep and 3" off the wall. for example
> or could 6 of 2 x 2 maybe spread out produce a "better " result
> 
> any data or testing to illustrate real scientific differences?


Spreading absorption panels apart gives a free boost in LF absorption, more so between 250 hz and 80 hz (probably lower too), by as much as 60% absorption coefficients in the below example layout. This boost is larger the lower frequency that you go, in the frequency region that wool (glass wool, rock wool, cotton wool, etc) absorbers tend to perform much less well at -- it's not enough to flatten the absorption across all frequencies, but it helps. 

For example consider 
a) one absorption panel 12 foot by 12 foot by 4 inches deep.
vs
b) four absorption panels 12 foot by 3 foot by 4 inches deep, with a 3 foot (wall) space between.

They have the same surface area. All with frames so only the front is exposed (side 4 inches are covered).


For clarity, (b) absorbs more than (a), especially in the below 250hz region.



Similarly a checkerboard pattern is better than putting them all together, if the same wool surface area is used.

(The same area, used diagonally across corners, gives a much larger bass absorption boost, as much as 450% ~ 100hz; this goes beyond merely flattening the absorption coefficients by frequency, the coefficients are higher in LF.)

Above comments are mine (with error due to simplification), based on the work of the late great Eric Desart "Playing With Baffles" (with Prof. Dr. Ir. Gerrit Vermeir).


----------



## asarose247

^ 
simplification and insights/science greatly appreciated
thank you


----------



## myfipie

BasementBob said:


> Spreading absorption panels apart gives a free boost in LF absorption, more so between 250 hz and 80 hz (probably lower too), by as much as 60% absorption coefficients in the below example layout. This boost is larger the lower frequency that you go, in the frequency region that wool (glass wool, rock wool, cotton wool, etc) absorbers tend to perform much less well at -- it's not enough to flatten the absorption across all frequencies, but it helps.
> 
> For example consider
> a) one absorption panel 12 foot by 12 foot by 4 inches deep.
> vs
> b) four absorption panels 12 foot by 3 foot by 4 inches deep, with a 3 foot (wall) space between.
> 
> They have the same surface area. All with frames so only the front is exposed (side 4 inches are covered).
> 
> 
> For clarity, (b) absorbs more than (a), especially in the below 250hz region.
> 
> 
> 
> Similarly a checkerboard pattern is better than putting them all together, if the same wool surface area is used.
> 
> (The same area, used diagonally across corners, gives a much larger bass absorption boost, as much as 450% ~ 100hz; this goes beyond merely flattening the absorption coefficients by frequency, the coefficients are higher in LF.)
> 
> Above comments are mine (with error due to simplification), based on the work of the late great Eric Desart "Playing With Baffles" (with Prof. Dr. Ir. Gerrit Vermeir).


Hey Bob,

Great answer. Once I get a chance I will do a test with our Monster Traps in the standard 2'x2' spread on the back wall vs standard 2'x4' panels pushed together, on the back wall and post the results. 

Just a note though, when it comes to places like early reflection points I have found that having larger panels is better vs covering that area *needed* with spaced out panels.


----------



## Its Chris

Hi,
I've come from the REW thread  I've started to look into sorting out the sound in my home cinema room. I've had issues in the past and have just not got round to getting a start on sorting them. One main problem I have is that I didnt research enough when I was doing the room and I have a set of shelves installed either side of the screen. The AV gear is on the right. I realise now though that I should have had all of this installed at the back of the room. I would like to try and sort the room without having to start taking shelves out and rewiring power etc..

To start I have an acoustically transparent screen with the center speaker in behind. However there is also a big enough space behind the screen which I should fill. But I'm wondering if I should pack the entire space with insulation (rockwool) or if I would get away with place panels directly behind the screen and leaving the space? I can also put absorbtion panels above and below the screen. With regards to the shelving. On one side it was for bluray storage and the other the av gear. I could fill the unused spaces, and on the bluray side fill the backs, behind the blurays with absoption panels/insulation (although with the blurays at the front this would probably reflect the sound....)

At the moment he main issue I have is the lower frequency, takes quite a while to die off. Pretty new to this aspect of home theatre so its a learning experience. Any advice would be great 

(Pics attached, dont have the pics with screen up on this PC, but pics added to show space behind screen. - and yeah I know, radiators will cause problems too )

Cheers.

Chris.

I will likely do this myself, buying the insulation etc. But have spotted some kits here in Ireland like the following : Link. Any opinion on that or is it overpriced for what it is?


----------



## Jonathan DA

Hi All,

Has anyone ever tested the absorption properties of paper backed wood veneer (usually 10 mil thick) bonded to something like 2" OC 705? I need to increase the amount of absorption in my room design below 300Hz. My front wall and rear walls are already taken up with treatments, and I only have 2" of depth available on the side walls. How would I go about testing the performance of this strategy without building a ton of them and potentially wasting a lot of money?

TIA,

Jonathan


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## Jonathan DA

Its Chris,

What is behind the large panels surrounding the screen? Empty air? I would think you could fill the space behind the screen along with removing those panels and fill those spaces too with a membrane trap covered by a porous absorber. That would eat into your decay times across the spectrum.

Also, if you're coming from the REW thread, do you have measurements of your current room?


----------



## nb67

As a general rule of thumb is better to have absorption at first reflection points? I have placed acoustic panels throughout my room to get rid of a slap echo and to be honest it sounds a little dead to me. Great for bass but, I don't know, just something missing, hard to put my finger on it. I have a few diffuser panels and want to integrate them into the room but not sure on placement. Any advice is appreciated.


----------



## Airbornesfc

Anyone put fake stone along the lower 1/3 of your side walls? Thinking of doing this but know it's not the best to use.


----------



## blazar

Airbornesfc said:


> Anyone put fake stone along the lower 1/3 of your side walls? Thinking of doing this but know it's not the best to use.


I have real stone on the bottom quarter of my room along with hard floors. Abrsorptive rugs and furniture are a must in that setting.


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## Jonathan DA

nb67,

Yes, generally absorbers at first reflection points are a good thing. Your absorbers may be acting like an EQ, however. If you've absorbed all your highs but not affected the reverb time of your mids and lows then I could totally see how that would sound dead. What kind of absorbers are you using, where did you place them, and how big are they? And how big is your room?


----------



## Jonathan DA

Airbornesfc,

As long as the fake stone is below ear level, I don't think you'll have a problem. It would behave like a mass loaded bare wall, I think. Maybe with a little diffusion at high frequencies too.


----------



## nb67

Jonathan DA said:


> nb67,
> 
> Yes, generally absorbers at first reflection points are a good thing. Your absorbers may be acting like an EQ, however. If you've absorbed all your highs but not affected the reverb time of your mids and lows then I could totally see how that would sound dead. What kind of absorbers are you using, where did you place them, and how big are they? And how big is your room?


The room is 12'x18', so fairly small. I used http://www.acoustimac.com/acoustic-panels/dmd-acoustic-panels/. In the diagram the red are roof to floor bass traps (24x48x6), except the one off below screen. Orange are acoustic panels, 24x48x2. Yellow panels are on the roof slope and are 24x24x2.
Black are speakers (5.4 system), rear is 2 x subs stacked behind sofa and blue is sofa, green is screen.
System is using Audyssey xt32, and dspeaker dual core for eq, although for 2 channel audio I prefer to run without eq or subs.
I'd say about 70% of the time I'm watching movies but 30% enjoy kicking back with beer and enjoy some 2 channel audio. So trying to get the best out of HT and 2 channel audio. I know that there are fundamental differences but I'm trying to find the happy medium.


----------



## Its Chris

Jonathan DA said:


> Its Chris,
> 
> What is behind the large panels surrounding the screen? Empty air? I would think you could fill the space behind the screen along with removing those panels and fill those spaces too with a membrane trap covered by a porous absorber. That would eat into your decay times across the spectrum.
> 
> Also, if you're coming from the REW thread, do you have measurements of your current room?


Hi Jonathan,
In the unpainted image, the white column on the right is the chimney breast. I put in a false wall then to even that end of the room so I could place the screen on it. The wall is just MDF and nothing (empty) in behind the screen. If I was doing this again I would have my equipment at the back of the room. But it would be quite a lot of hassle to start moving all this round! It would cost me around €300 to fill behind the screen with the rolls of rockwool. I had figured if I made a few panels from RW3 and placed then in the opening of the wall behind the screen, and then put panels above and below the screen (obviously these wouldnt be the same thickness as the ones behind the screen). I could also pack the top shelves with some RW3 panels cut and leave one or two for equipment. But I know that the shelves and the ones with equipment will still cause issues. 

REW : Link (Smoothed the sub tests by mistake - so need to be unsmoothed)


----------



## Jonathan DA

nb67,

First, let me caveat this by saying I'm just amateur whose read a lot and done some experimenting. If one of the pros chimes in with differing advice - follow their recos over mine. That said, your room doesn't look too dead to me. A few thoughts:


I assume you re-ran your Audyssey calibration routine after the treatments were installed. If not, that's step 1.
I'm also guessing that during movies, the sound is good, but it's during two channel listening that you feel it's too dead, correct?
There is a chance you're just used to a live room and prefer it. If that's the case, you just need to remove some treatments. Or give yourself time to adjust to the sound.
If #3 isn't true, then you may have over deadened the room because of some unique property of it (vaulted ceilings, wall construction, etc.). Let's assume that's true for now.
If you're handy with computers, I'd suggest getting REW and measuring your room. That will help pinpoint the problem areas, but there's also a steep learning curve. 
If you don't want to mess with REW, you might try experimenting with your back wall first. Try removing the rear absorbers all together. Then try putting them back and covering them in kraft paper. Then do the same thing with the side wall treatments. Floyd Toole (famous acoustics guy and speaker designer) actually suggests that side wall reflections can be a good thing.
What speakers are you using? You may have some unusual off axis response that when combined with the less-than-full spectrum absorption on the side walls is causing some odd frequency response in the reflected sound that reaches your ears. In which case you might want some diffusion in combination with the absorbers at the first reflection points instead of pure absorption.


----------



## Its Chris

Doing some testing here. If you play a 38.5hz tone, either side of the room seems loud, middle is fine. Front two corners seem to be higher but back corners not as much, maybe the slanted ceiling also has an effect?


----------



## Jonathan DA

Its Chris,
How deep are those shelves in the corners? Are they deep enough that could spare 4-6" of depth at the back of them? If so, you could build VPR bass traps into them and then just put your equipment in front of them. Or buy them. Like the RPG Modex panel.

I think I'd also take down the MDF and use all that space plus the space behind the screen to build a compound trap. A porous layer with a plastic membrane behind it, then as much thickness of fiberglass as you can put behind the membrane.


Also, I'd check into which room dimension is causing that 178Hz peak in your measurements. If that's a width related mode, then you probably need something on the side walls to kill that.


----------



## Its Chris

Jonathan DA said:


> Its Chris,
> How deep are those shelves in the corners? Are they deep enough that could spare 4-6" of depth at the back of them? If so, you could build VPR bass traps into them and then just put your equipment in front of them. Or buy them. Like the RPG Modex panel.
> 
> I think I'd also take down the MDF and use all that space plus the space behind the screen to build a compound trap. A porous layer with a plastic membrane behind it, then as much thickness of fiberglass as you can put behind the membrane.
> 
> 
> Also, I'd check into which room dimension is causing that 178Hz peak in your measurements. If that's a width related mode, then you probably need something on the side walls to kill that.


Yeah removing the MDF probably would be better, alot of work though!  Then need to still sort it so that it blends, fills space left by MDF and the screen still hangs securely. Shelves are 45cm deep. I could fill all of them apart from two each side. This started out as a simple play around with REW after I was planning on buying new rear speakers to upgrade to 7.1. I've since bought the UMIK mic, and looking at hundreds to sort the sound.... Ignorance is bliss sometimes! (but always knew there were issues) How do you check which room dimension is the cause?


----------



## Jonathan DA

Welcome to the club  My room (when it's finally finished) will, by far, be the most expensive piece of equipment in my system.

To check the room dimensions, you can figure out how long a 180Hz wave is (you can find calculators via Google) and then see if a multiple of that wavelength matches a dimension of your room. You can also go into the room sim in REW and model your room. It will predict where the modes are for you. It will be off in your case, though, because you have a vaulted ceiling, but it might give you a good idea of where to start looking.

It's also possible (probable even) that the 180Hzish problem is SBIR.


----------



## Its Chris

Jonathan DA said:


> Welcome to the club  My room (when it's finally finished) will, by far, be the most expensive piece of equipment in my system.
> 
> To check the room dimensions, you can figure out how long a 180Hz wave is (you can find calculators via Google) and then see if a multiple of that wavelength matches a dimension of your room. You can also go into the room sim in REW and model your room. It will predict where the modes are for you. It will be off in your case, though, because you have a vaulted ceiling, but it might give you a good idea of where to start looking.
> 
> It's also possible (probable even) that the 180Hzish problem is SBIR.


Ha, I can see how that happens! Its a hard thing to justify spending money on to the other half!! Even though she gives out about the sound being too loud at times, then turns it down only to turn it up after actions sequences are finished  I've attached an image of the front wall before the MDF panels went on. Have one of the excel sheets with the calculator here. Will check it out. Cheers.


----------



## BasementBob

Jonathan DA said:


> To check the room dimensions, you can figure out how long a 180Hz wave is (you can find calculators via Google) and then see if a multiple of that wavelength matches a dimension of your room.


http://www.bobgolds.com/Mode/RoomModes.htm


----------



## BasementBob

Its Chris said:


> Even though she gives out about the sound being too loud at times, then turns it down only to turn it up after actions sequences are finished


That's why soundproofing is important. If the noise floor of the room is low enough, you can keep the volume down and constant throughout the movie. With a low noise floor, there's less masking noise making the talking portions inaudible, and when the action sequences start its not painfully loud.

I wonder if there's a receiver with a max volume (dB(C)) limiter. So that quiet scenes are still quiet, talking scenes are easily audible (near the set max volume), but you don't scare the neighbours at the action sequences because the limit lowers the volume knob temporarily (or when you walk to the kitchen during a commercial that gets horribly loud when you're too far from the remote to shut it down)


----------



## AllenA07

I'm thinking about taking the jump and doing my first set if treatments. While I'm currently thinking about bass traps and points of first reflection, my question is how to deal with my side surrounds being bipoles? W would I want to leave the front and back wall untreated in that case?


----------



## nb67

Jonathan DA said:


> nb67,
> 
> First, let me caveat this by saying I'm just amateur whose read a lot and done some experimenting. If one of the pros chimes in with differing advice - follow their recos over mine. That said, your room doesn't look too dead to me. A few thoughts:
> 
> 
> I assume you re-ran your Audyssey calibration routine after the treatments were installed. If not, that's step 1.
> I'm also guessing that during movies, the sound is good, but it's during two channel listening that you feel it's too dead, correct?
> There is a chance you're just used to a live room and prefer it. If that's the case, you just need to remove some treatments. Or give yourself time to adjust to the sound.
> If #3 isn't true, then you may have over deadened the room because of some unique property of it (vaulted ceilings, wall construction, etc.). Let's assume that's true for now.
> If you're handy with computers, I'd suggest getting REW and measuring your room. That will help pinpoint the problem areas, but there's also a steep learning curve.
> If you don't want to mess with REW, you might try experimenting with your back wall first. Try removing the rear absorbers all together. Then try putting them back and covering them in kraft paper. Then do the same thing with the side wall treatments. Floyd Toole (famous acoustics guy and speaker designer) actually suggests that side wall reflections can be a good thing.
> What speakers are you using? You may have some unusual off axis response that when combined with the less-than-full spectrum absorption on the side walls is causing some odd frequency response in the reflected sound that reaches your ears. In which case you might want some diffusion in combination with the absorbers at the first reflection points instead of pure absorption.


You are correct on point number #2 . I do re-run eq after changes in the room but I do like your idea of removing some absorption at the rear of the room. I'm thinking about replacing some of them with diffusers. I have ominmic so will run more sweeps and look to where my issues might be. To be honest, I have focused on getting


----------



## Jonathan DA

BasementBob said:


> I wonder if there's a receiver with a max volume (dB(C)) limiter. So that quiet scenes are still quiet, talking scenes are easily audible (near the set max volume), but you don't scare the neighbours at the action sequences because the limit lowers the volume knob temporarily (or when you walk to the kitchen during a commercial that gets horribly loud when you're too far from the remote to shut it down)


That's basically the same effect as using dynamic range compression, or "night mode," yes? The difference being it's making the loud passages softer and the soft passages louder.


----------



## asarose247

speaking of stone . . .
has anyone tried this flagstone gossamer from Stumps for panel covering? maybe over a black muslin?

http://www.stumpsparty.com/event/flagstone-gossamer/pgp/p0409e


----------



## Its Chris

BasementBob said:


> That's why soundproofing is important. If the noise floor of the room is low enough, you can keep the volume down and constant throughout the movie. With a low noise floor, there's less masking noise making the talking portions inaudible, and when the action sequences start its not painfully loud.
> 
> I wonder if there's a receiver with a max volume (dB(C)) limiter. So that quiet scenes are still quiet, talking scenes are easily audible (near the set max volume), but you don't scare the neighbours at the action sequences because the limit lowers the volume knob temporarily (or when you walk to the kitchen during a commercial that gets horribly loud when you're too far from the remote to shut it down)


Yeah the noise floor in the room is about 45-50db. There is a mode similar to that on my current receiver and no doubt there will be one on (most) the new receiver I get in future. I think if I got the sound absorption sorted in the room it might help.


----------



## Its Chris

Jonathan, in that last image I posted you can see the structure of the wall. If I left the MDF face on and cut out holes where the gaps between the struts are and filled each of these with RW3 panels I could cover the front then with Devore fabric, which I had planned to do at some point. Then fill behind the screen with oridnary Rockwoll roll insulation. For the corners, if I filled all the shelves bar let say 2 on each side, with RW3 with a depth pf RW of 4-8 inches. There would be an air gap behind of about 7 inches. It would leave me with a few shelves open. Also with the open shelves I could fill each at the back with about 4 inches at least (apart from the av receiver shelf).


----------



## Jonathan DA

Chris, I think that would be a good approach. You might want to just do behind the MDF and screen first, then measure it with REW if you can. That way you'll have a better idea of what to do in the corners. You might just want more broadband absorbers in the corners, or you might want to try something a little more intense, like a modex style trap.


----------



## blazar

On he earlier question about doing stone in the room.

I might add: the bumpier/rounder the better. You can never have "too much" diffusion.

I have rough stone and i even had the masons step some of the stones at different depths. I used a variety of stone sizes to get a specific look.

A lot of the fabricated stone products are fairly flat and therefore not as useful in my mind. Consider doing an actual masonry wall.


----------



## asarose247

I originally posted this in the home ATMOS thread, seemed to make sense at the time
the applause of 1 hand clapping was thunderous 



ATMOS related question

This excert from Dennis Erskine , post 4 in 2003, this Dedicated thread:

Requirements for multi-channel (more than 2) are different than that required for 2 channel.

In multi-channel, the entire wall behind the front speakers is treated. You want none of the back reflections to overlay the surround field or the bring the reverberent field forward (your reverberent field and surround field is created by the multi-channel processor or mix, not so much the room as is mandatory for 2-channel). Depending on speaker placement, this treatment is brought forward along the side walls. Wall treatments are floor to slightly above ear level (where exactly is also a function of front speaker heights). While one could argue the sound at their feet is of no concern, often that square footage of treatment is required to bring the room's RT60 down to the lower levels required for multi-channel playback.

WHEW!

I'm looking to hear comments or results and why or why not, now that speakers are on/in the ceiling, how some / none of this logic and science might/should/could be applied to ceiling panels specifically angled for mitigation of off-angle , time delayed reflective response wrt enhancing ATMOS/DSU mixing clarity in integration of the overhead sound field .
Sure, we want immersion but do we need ALL the "sound" being put out up there ?
after-all we have to have panels for 1st reflective points , bass traps, clouds, stepped clouds, absorbers, diffusers, tympanic membranes, etc.
In keeping up with this (originally ATMOS) thread, my impression is that for early adopters, not so much an issue, it was a new toy, we'll catch up with the real work a bit later, many probably already have done the smart part of that work wrt overall basic/scientifically guided treatment . 

I'm thinking angled clouds , of course getting them up "there" is a whole 'nother discussion
Any constructive comments,, links, experiences, thoughts appreciated

Thanks


----------



## Jonathan DA

Asarose247,

My totally unqualified opinion is that as you add more speakers to more surfaces, you reach a point where you want a consistent behavior throughout the room. D'Antonio (of RPG fame) coined the term Ambechoic to describe a room that uses massive diffusion to create an almost-instant 30dB drop in the ambient sound field vs. the direct sound reaching your ears. It would seem that this would be an ideal environment for virtually any surround sound speaker arrangement. You can see his presentation slides about it here: http://www.rpginc.com/docs%5CTechnology%5CPresentations%5CMedia%20Room%20Design.pdf

As you can see from the Blackbird Studio example in the document, achieving an ambechoic room requires a crazy amount of space and money. The iRoom design in the document might be a decent approximation (I've never heard one, wouldn't know for sure). Another approach to achieve similar results is the MyRoom design method that Bogic Petrovic and Zorica Davidovic developed. It achieves similar goals to the Ambechoic design, but uses less space and is considerably cheaper. http://www.myroom-acoustics.com/host...hite_paper.pdf

Cheers,

Jonathan


----------



## Jonathan DA

The other thing I'd throw out there is that if you look at Erskine group's more recent designs, it looks like they've moved beyond Dennis' advice from 2003. I wouldn't consider the post you quoted to be gospel these days.


----------



## BasementBob

Jonathan DA said:


> The other thing I'd throw out there is that if you look at Erskine group's more recent designs, it looks like they've moved beyond Dennis' advice from 2003. I wouldn't consider the post you quoted to be gospel these days.


 
What would the changes you recall, be?
(Or do you think they're using more math/acoustics specific to each installation, rather tweaking a generic design. Thus no consistent new generic design.)


----------



## Jonathan DA

I don't know any of the internal workings of Erskine Group, but from what I can tell of publicly available photos it looks like they design each room uniquely (which seems like a best practice) and they often use treatments that are, or almost, floor to ceiling. It's just that the treatments vary by position - some are absorption, some diffusion, some combination devices. The Quest acoustical system they use seem tailor made for this given its modular approach. I see the same practice from other pros like Nyal at Acoustic Frontiers. His video about the Savoy build gives a good description of why we need to do a unique treatment strategy for each room/speaker combination.


----------



## Jonathan DA

BTW, I do recognize that it sounds like I'm contradicting myself in the two posts above. On one hand I say each room/speaker treatment strategy needs to be unique, but then I say an Ambechoic approach would probably work for anything. I guess my point is that since most rooms can't achieve an Ambehoic response, a unique treatment strategy is required instead.


----------



## asarose247

thanks for the updates of science , practices and links
time for more research
back to the drawing board


----------



## asarose247

In the long term, this was certainly no simple question , never was . . .
and certainly there is no "simple" answer, especially without a good long learning curve for the non-professional

The short answer is: write a check


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## artur9

BasementBob said:


> What would the changes you recall, be?
> (Or do you think they're using more math/acoustics specific to each installation, rather tweaking a generic design. Thus no consistent new generic design.)


My understanding from reading this whole thread from top-to-stern and keeping subscribed is that in the early days absorption was favored and very little diffusion was used. That lead to excessively deadened rooms.

The more au courant treatment method uses more diffusion and more targeted absorption. With small rooms (whatever that means) it may not be possible to diffuse enough, however.

IIRC, AIUI throughout.


----------



## dnoonie

I just ordered up 6 ATS Acoustic Diffusers 23" x 48" x 6", QRD 7 type for the back area of my HT room. 

I'll be replacing rear first reflection absorbers with two of these. I'll be putting 2 on the back wall while leaving bass absorbers. I'll be hanging 2 on the ceiling over rear surrounds over bass absorbers.

Look under "Clearance" they have them for nearly half price, http://www.atsacoustics.com/acoustic-diffuser-clearance.html . They are unfinished but it's pretty easy to use wood  stain and varnish or a one step product.

I'd get more but I really don't have room for them till I do at least remodel the existing theater room

I've not ordered from ATS before so if you want to wait and see what my experience with them is I'll be happy to post back.

I'll post back when they arrive but they're not supposed to ship till 6/2 or 6/3.

Cheers,


----------



## jaychatbonneau

Hi, guys!

I am doing my first home theater build and using sound treatments for the first time. I came across tube-shaped bass traps in the wholesale market dedicated to audio and home theater here in Guangzhou. Do these things actually work? They seem way too light to function as a bass trap. What am I missing?

Thanks!


----------



## HopefulFred

They do work - probably. Some designs might actually be pretty good. Other designs are only useful over a very small bandwidth. Hard to say.


----------



## Squirrel!

Good morning group,

Will get better pics, but this to start:

The pic is of my handicapped sons duplex. The echo is simply maddening. I placed an area rug, some vinyl blinds, some darkening drapes...The couch is pleather/vinyl, glass front picture hanging, vaulted ceiling(s) that opens into a very open kitchen, also with vaulted ceiling. 

The plan: To make my own frame box, covered in sound deadening blackout drapery material. Question is how large, many and ideal placement? 

The plan: 1 4x2 behind each tower and one 4x2 above the TV. 3 - 4x2 on the opposing wall above the couch...one near the front windows about 8" above couch back, the hanging picture moved to center over couch with 4x2 oblong above the picture (if space allows, this one may be sized to fit), and the 3rd panel above the end table.

Thoughts: Unseen as of yet, but thinking I will still need more treatments going into the DR/KIT open area. 

Suggestions are most welcome as this I am just learning about, for the sole purpose of echo control on the cheap (but effective).


----------



## HopefulFred

4x2 is a fine size and you're off to a pretty good start with the locations. If you are only using the stereo pair of speakers, with no center and normally not using the TV speakers, then the panel centered on the TV may be superfluous. The panel behind the listeners should come all the way down to be as close to the top of the couch as you can tolerate: directly behind your head.

You said, "sound deadening blackout drapery material." This is only part of the story. The panels need to be thick - like four inches thick - and filled with some kind of fibrous absorption - like rockwool; the classic recommendation for this sort of application is Owens Corning 703, but there are other similar products available. If you do that, the covering is a lot less important. In fact, the covering is best as a thin cheap fabric; again there are several options, but they should allow the sound to pass through them into the mineral wool interior.

If three panels in those locations is insufficient, I'd suggest even thicker panels in the corners, to help with bass response.


----------



## SandstormGT

I am just starting on a spare bedroom theater project, it won't be anything major. I haven't decided where/if I am going to put the side/rear surrounds yet but I already have my L/R SVS Ultra Bookshelf's on 32" Transdeco speaker stands off to the side of the console(not pictured) and a SVS SB-2000 up front(not pictured). Listening position will be around 4' from rear wall. I plan on building a window plug for the only window in the room.

To get started on acoustic treatment, my plan was to put 1-2 GIK TriTrap(s) in the left corner(only corner available) and to be symmetrical, I was going to put a bass trap to the right side as well(not a corner), but didn't know which bass trap would be a compatible match to the TriTrap, a Monster Trap or a 244 Trap, with or without range limiter?

TL;DR:

1) Glenn, what GIK bass trap matches the TriTrap best, and with/without range limiter?

2) For anyone, I am not going all out on first purchase. Does my plan of bass traps on front two corners and a 2'x4' Monster Trap on the rear wall behind the couch sound like a good plan?

3) For anyone, my USB UMIK-1 is on it's way, would it make sense to set this up and completely learn REW before even thinking about what acoustic treatments to get? I think it's pretty clear by my room size/shape that I will need bass absorption before even opening REW.


----------



## myfipie

jaychatbonneau said:


> Hi, guys!
> 
> I am doing my first home theater build and using sound treatments for the first time. I came across tube-shaped bass traps in the wholesale market dedicated to audio and home theater here in Guangzhou. Do these things actually work? They seem way too light to function as a bass trap. What am I missing?
> 
> Thanks![/QUOTE
> 
> 
> The shape really has not influence on absorption. It really comes down to size (larger the better). If made from foam I would not think they are doing much.


----------



## asarose247

@SandstormGT
after looking at the room size above, not much different than mine
from my own learning,
listening to a variety of vids from "acoustic fields' dennis foley, & others from you tube
i was going "Hmmmmm!" after a discussion of room size and the realistic possibilities of "effective ' (?) treatment
when
his advice was, if a room is less that 1500 ft^3, get a bigger room . . . .
after that I sent him a description of my man cave
this:
In my small room < 10' x 11' closer to 100 sq.ft. About 900 ft^3
in the right front corner standing up, a 30" THTLP, loading distance to the ceiling 20+"
in the left rear corner standing up, a 24" THTLP, distance 21+" (because I could , that's why)
using a Denon X4000 and its separate sub EQ thru 2 BASH 300's, xo 80
immersing and most authoritative to say the least
L/C RB 51's C: G-28, Sl/r S-10's , RS (one)SLX, Front highs some big ass RS3II's all Klipsch,
XT32 does nicely using PlIIx, Neo:X etc. for music and movies 
and 4 Aura shakers with a PE 250 watt amp on the seating for good measure
and a 73" Mitsy DLP for visuals , with a new lamp
a panasonic BD that does 2d>3d 
Direct TV, my laptop, 3T drive full of stuff
total light black-out, heavy lined draped walls 
a background noise level of 37-38 dB
windows stuffed with 3” roxul S&S
free standing 16 x 47 3” Roxul 1st reflection pt. panels

so if by using what i can between the 
avr, audyssey and whatever else I can stuff in there try to make it sound as clear and "unsmeared"
but the difference in Gravity even in Neo, no ATMOS or DSU Neo in my bigger room and this small spot
well there is no room for openess or great panning spaciousness

so "settling" but not without a fight for " near field intimacy"

for tonight I'm putting 2 more 2 ish x 4 ish 3" roxul panels on the wall behind the TV in the vicinity of the bookshelves mains.

keep us posted on what you do and PICS!


----------



## asarose247

@SandstormGT
after looking at the room size above, not much different than mine
from my own learning,
listening to a variety of vids from "acoustic fields' dennis foley, & others from you tube
i was going "Hmmmmm!" after a discussion of room size and the realistic possibilities of "effective ' (?) treatment
when
his advice was, if a room is less that 1500 ft^3, get a bigger room . . . .
after that I sent him a description of my man cave
this:
In my small room < 10' x 11' closer to 100 sq.ft. About 900 ft^3
in the right front corner standing up, a 30" THTLP, loading distance to the ceiling 20+"
in the left rear corner standing up, a 24" THTLP, distance 21+" (because I could , that's why)
using a Denon X4000 and its separate sub EQ thru 2 BASH 300's, xo 80
immersing and most authoritative to say the least
L/C RB 51's C: G-28, Sl/r S-10's , RS (one)SLX, Front highs some big ass RS3II's all Klipsch,
XT32 does nicely using PlIIx, Neo:X etc. for music and movies 
and 4 Aura shakers with a PE 250 watt amp on the seating for good measure
and a 73" Mitsy DLP for visuals , with a new lamp
a panasonic BD that does 2d>3d 
Direct TV, my laptop, 3T drive full of stuff
total light black-out, heavy lined draped walls 
a background noise level of 37-38 dB
windows stuffed with 3” roxul S&S
free standing 16 x 47 3” Roxul 1st reflection pt. panels

so if by using what i can between the 
avr, audyssey and whatever else I can stuff in there try to make it sound as clear and "unsmeared"
but the difference in Gravity even in Neo, no ATMOS or DSU Neo in my bigger room and this small spot
well there is no room for openess or great panning spaciousness

so "settling" but not without a fight for " near field intimacy"

for tonight I'm putting 2 more 2 ish x 4 ish 3" roxul panels on the wall behind the TV in the vicinity of the bookshelves mains.

keep us posted on what you do and PICS!


----------



## dnoonie

dnoonie said:


> I just ordered up 6 ATS Acoustic Diffusers 23" x 48" x 6", QRD 7 type for the back area of my HT room.
> 
> I'll be replacing rear first reflection absorbers with two of these. I'll be putting 2 on the back wall while leaving bass absorbers. I'll be hanging 2 on the ceiling over rear surrounds over bass absorbers.
> 
> I've not ordered from ATS before so if you want to wait and see what my experience with them is I'll be happy to post back.
> 
> I'll post back when they arrive but they're not supposed to ship till 6/2 or 6/3.
> 
> Cheers,


The diffusers I ordered arrived day before yesterday and the UPS delivery person rolled the boxed diffusers end over end from the truck to my house. Of the 6 I ordered all were damaged, 2 were damaged on the back and are still usable but not the rest. ATS is graciously replacing the 4 I asked to be replaced.

I've had similar problems with UPS and FedEx ground shipments for about 10 years. I'm wondering if this is something unique to the Seattle area.

ATS packaging looks very good but not good enough. They likely need double boxed or better yet... I've had better luck shipping heavy bulky items palatalized and by freight. It's a pain since you have to pickup the items at the shippers warehouse but at least the items are safe.

I'm still trying to decide on what color stain too use. Dark Cherry is too dark and Light Cherry is too light, I'm thinking Cabernet, Red Chestnut or Red Mahogany.

If my upgraded theater ends up looking finished enough I might start a thread for it. I'm thinking I'll run out of money before I get to that point. Getting some other upgrades (furnace ducts, insulation) is the priority now but if I have enough left over after that I might get theater seats and build a nice soffit, at that point I'd consider doing a writeup.

Cheers,


----------



## myfipie

> 1) Glenn, what GIK bass trap matches the TriTrap best, and with/without range limiter?


The 244 and the Monster have a nice peak of absorption at around 80hz (down to around 60hz) where the Tri Trap is a unit that is designed to go to 50hz, but does not have the peak at 80hz. If you want something close then I would go with the Monster. In your case I would go full range as you are not starting out with all that much so you really don't need to worry about over absorbing the upper frequencies at this point. 




> 2) For anyone, I am not going all out on first purchase. Does my plan of bass traps on front two corners and a 2'x4' Monster Trap on the rear wall behind the couch sound like a good plan?


Plenty of my customers start with a small amount as you are thinking then add over time.


----------



## dnoonie

myfipie said:


> Plenty of my customers start with a small amount as you are thinking then add over time.


I treated what I knew I should treat, 2" at first reflections both side and ceiling and 4" corner bass traps. Then I tested with TrueRTA to find out what to do next and choose absorbers accordingly. I've still got listening space problems due to some open walls and doorways and maybe some other problems that I won't know about till I fix the walls and doors, but one step at a time, you've got to start somewhere.

Cheers,


----------



## jdaddieo

So, for HT use where would be the most beneficial placement of diffusion panels? My room is 18"W X 15'D X 7' 10"H. I have read on acoustic sites, books and forums several different theories on placement from overhead at the main LP, back walls and even suggestions for side walls. I have experimented with treatments on my room and have it sounding "about right" with absorption panels and getting good results from REW but I feel it could use some diffusion to enhance separation for my 9.2 speaker set-up.


----------



## dnoonie

jdaddieo said:


> So, for HT use where would be the most beneficial placement of diffusion panels? My room is 18"W X 15'D X 7' 10"H. I have read on acoustic sites, books and forums several different theories on placement from overhead at the main LP, back walls and even suggestions for side walls. I have experimented with treatments on my room and have it sounding "about right" with absorption panels and getting good results from REW but I feel it could use some diffusion to enhance separation for my 9.2 speaker set-up.


This is my first first hand experience experimenting with diffusion so I don't know for sure what exactly to expect. What inspired me to get some diffusion was a visit to the Seattle Cinerama, http://www.avsforum.com/forum/44-mo...christie-lamp-dolby-atmos-2.html#post34181714.

Based on that experience I'd say that the diffusion there didn't help separation but did make the room sound more spacious. I liked the sound enough to want to try it in my little theater, 11' 7" x 16' 5" x 7' 8".

With my current setup I get stereo FX way beyond the speaker placement now. I get these FX (sounds up to 4 feet beyond the speaker) mostly with stereo recordings that go out of their way to produce that effect and less so with movies even through they're multichannel. Even so most movie FX go several feet beyond the speaker placement.

Cheers,


----------



## billqs

I'm working on treating my dedicated home theater. While doing the clap test, I have noticed a metal resonance. Upon inspection I have determined it is the 2' x 2' metal register that delivers the hvac into the room. What would be a good way to deaden it, so that it would no longer vibrate and make noise?


----------



## dnoonie

jdaddieo said:


> I have read on acoustic sites, books and forums several different theories on *placement *from overhead at the main LP, back walls and even suggestions for side walls..


I'll be putting my new diffusers on the back wall and back of the side walls. Several places recomond not putting diffusion closer than 1' of the listening position for each inch of depth of the diffuser (if that doesn't make since just say so, I think I wrote that right), so in my small space that limits placement. I may try moving some around behind the front speakers or beside the front speaker, I'll make some stands to set them on/in so I can experiment once I get the little remodel of the theater room finished. I already have diffusers across the top of the front wall.

Perhaps you're already seen but..
http://www.acousticsfirst.com/artic...eat-your-home-theater-like-a-real-theater.htm
http://www.gikacoustics.com, their videos have some tidbits as does every other seller of diffusers.

Cheers,


----------



## BasementBob

I've watched the Pod Race (Star Wars Episode 1) in a highly reflective environment, and heard the pods moving left to right when on the screen they were moving right to left -- very poor imaging. And then after putting up first reflection point absorbers, suddenly the sounds of the pod race were in directional sync with the video -- very good imaging. Left me with the impression that the first place to put acoustical treatment is wherever fixes the Pod Race.


----------



## dnoonie

billqs said:


> I'm working on treating my dedicated home theater. While doing the clap test, I have noticed a metal resonance. Upon inspection I have determined it is the 2' x 2' metal register that delivers the hvac into the room. What would be a good way to deaden it, so that it would no longer vibrate and make noise?


Here's some thoughts:
* take it out and see if that area still has a vibration, maybe it's the duct and not the air vent diffuser
* replace it with a heavier duty one
* bend the veins to see if you can get it to stop vibrating
* replace with a nice looking wood air vent diffuser 
* tighten and loosen the screws that hold it in place
* jam something under a corner of it to see if you can tweak/twist it to get it to stop vibrating

I've messed with stuff like this before and even if you find a fix for the air vent diffuser you have now it will likely start vibrating again sometime in the future. I think your best bet is replacement.

http://www.raymon-hvaconline.com/
https://www.google.com/search?q=24x...X&ved=0CDgQsARqFQoTCJSersCtkMYCFceUiAodOd0ASg
www.grainger.com/category/grilles/ventilation/hvac-and-refrigeration/ecatalog/N-jze
http://www.grainger.com/category/di...ssories/hvac-and-refrigeration/ecatalog/N-m1m
http://www.vandykes.com/air-vents-registers-grilles/c/331/

Cheers,


----------



## billqs

Thanks for the info. Unfortunately, it is one of those 3 layer metal diffusers so certain vibrations just leave it ringing like a bell. With that being said, its not terribly noticeable during content play. It just happens to reverberate at exactly the frequency of the hand clapping noise from the clap tests. I was thinking of putting foam weatherstripping around the 2 x 2 grid opening to see if that would help and/or attaching strips of fabric to the underside, taking care not to block the airflow, but probably replacement makes more sense. It's just a standard issue 24 x 24 diffuser for a drop ceiling. The duct work going to it is flexible material and hasn't added to the noise that I am aware of.

On the google page I saw an ABS made diffuser which comes in black and so would match my suspended ceiling. I may try that. It's not much more expensive than the regular metal ones.


----------



## myfipie

For a general clap test, I would recommend you sit in your seat and have someone clap over top of your speaker. What you are looking for is the relation of the sound coming out of the speaker to your seating spot. Not the sound generated from the seat, unless you clap all the time.


----------



## billqs

Thanks, Glen! Yeah I was walking around the room clapping. While I am pleased with my home theater, it doesn't lead me to spontaneous applause. 

I have another question or two about room acoustics. My room is 10x21x8 with a drop ceiling. I placed sound blankets on the walls and it really improved clarity in the treble. I knew, though, that lower mids and bass would need the help of bass trapping as the blankets don't carry full range protection. (They did help tremendously with flutter echo from the two parallel walls that are located only 10 feet from each other.) I should also mention I have 2 subs to attempt to help with some of the nulls in the room. One is placed left front and one is placed rear center.

I read on Ethan's site and using bags of insulation placed in a corner. I did a google search and found the Jon Risch Down and Dirty rolls of insulation left in the bags bass trap idea. I bought 6 rolls which gets me floor to ceiling if I stack all of them together. There is only one of the 4 corners I can do that, however, and that is the rear left corner as you face the screen (and that blocks the breaker box.) The rear right has the entrance door, I have wall to wall screen (133" diagonal 16x9 on a 10 foot wide wall) on my front wall so there's not room for floor to ceiling rolls of insulation on the left front wall, and my right front wall has the entrance to my equipment closet.

When I stacked them in the left rear corner, it attenuated the bass alright. Made it very anemic sounding. Also, I noticed a good bit of shrill highs I don't normally have. Since the insulation bags were near the left rear surround, I surmised the high frequencies were being reflected by the bag plastic and the lows were being absorbed. 

After that, I tried to put the insulation bags behind the speakers in the front left and right corners. I could only fit 2 high as my screen begins 36 inches from the floor. I put two in each of the front corners and last 2 in the rear left corner. I'm not sure that's enough to be effective as I didn't hear any big bass changes. (I don't have a real boomy bass problem, I'm aware of.) I also hear more high information but at a loss of the clarity I had gained. I put this down to first reflections bouncing off the plastic as well.

I have a couple of different questions.

1. Jon Risch suggested when covering the rolls of insulation fabic to install poly batting to absorb more of the higher frequencies. Would this tame some of the errant high frequencies I hear?

2. Would I do better to place all 6 insulation bags single file on the floor below the screen to cover that meeting of corners? It would gain me about 8 feet of coverage that way.

3. Is it worth doing floor to ceiling bass trapping in the rear left corner if that is the only corner I can do it in? 

Thanks for everyone's help!


----------



## billqs

I'm flattered to have the last word...  but I still hold out hope for some help. I've modified from the diagram above and moved all 6 bales of fiberglass to the corner between the screen wall and the floor, behind the speakers, but single file to see if that cut out some creepy sounding reflections. It appears to have worked, but I still don't feel the bass is "trapped" so to speak. I got material to polycover and burlap to wrap the bales so they are better looking, but I need honesty if this is not the best plan. I'm also not opposed to purchasing some bass traps at a reasonable price that could fit my stage. 

I know not many people go the acoustic blanket route, but it does seem to have noticeably quieted echoes. I do have _much _better definition in my high frequencies. I am also open to other ideas to help improve the sound.

Thanks!


----------



## HopefulFred

IMO with bass trap placement you have two options: use as many as you can stand; or take some measurements of the bass response and decay and use that to figure out which places need absorption.


----------



## billqs

Well, turns out 6 bales of fiberglass lined up under the screen still in their bags doesn't have a wonderful WAF score however the sight of them got me permission from "da boss" to order some actual bass traps that would look good in the room. Since I have 36 inches before I hit screen and 10 feet wide to place, I'm thinking 2 limp membrane 4" thick 4' x 2' panels would fit nicely under the screen. I might get one or two more for the rear of the room. My second sub is back there and there's nothing to tame the "savage beast" in the area at the moment. 

Am I right in thinking the limp membrane traps would offer me a bit more sophisticated solution than just putting rockwool in a burlap sack which is very effective but I could do DIY? I'm thinking about traps like the ReadyTraps or the GIK 244. Most corners in my room are occupied so I don't see much possibility of using a superchunk type design. (The one completely open corner has my breaker panel on one of the walls, so any corner trap there would need to be movable... also probably not the best idea to keep that panel behind fabric.) I could fit some Next Acoustics foam behind the door corner as they offer an 8 inch side and 12 side in their corner wedge foam to increase mounting possibilities. But my understanding is that foam is really not that useful for trapping bass.

There's also the possibility of putting thick batting above the drop ceiling, although I am death to ceiling tiles. Although not designed for sound blocking, that might also provide a bit of attenuation from the bedroom upstairs. Have to admit I'm really NOT looking forward to working above the drop ceiling again.


----------



## AidenL

Hi all,

So using 60kg/m3 Rockwool behind the screen, is it ok to just cover it with black acoustically transparent material? Similar to the Guildfordds of Maine material? 

I'm assuming this is mainly to stop fibres floating through the air? And to stop reflections from the light coloured Rockwool back through the screen?


----------



## BllDo

GOM would work fine. It's a little pricey for this use though. I used black speaker cloth from Rose Brand. Cheaper and still fire rated.

http://www.rosebrand.com/product800/102-Black-Speaker-Cloth-FR.aspx?tid=2&info=speaker+cloth


----------



## KanosWRX

AidenL said:


> Hi all,
> 
> So using 60kg/m3 Rockwool behind the screen, is it ok to just cover it with black acoustically transparent material? Similar to the Guildfordds of Maine material?
> 
> I'm assuming this is mainly to stop fibres floating through the air? And to stop reflections from the light coloured Rockwool back through the screen?


I did pretty much exactly what your doing, Roxul ATF behind my screen. I framed out the back and just put insulation inside, kind of like your building another wall. Then just covered it with fabric from Jo Ann fabrics, it was a very light black fabric so sound easily could go through. Very cheap. But you never really see it unless your behind the wall, so it works very well.


----------



## AidenL

KanosWRX said:


> I did pretty much exactly what your doing, Roxul ATF behind my screen. I framed out the back and just put insulation inside, kind of like your building another wall. Then just covered it with fabric from Jo Ann fabrics, it was a very light black fabric so sound easily could go through. Very cheap. But you never really see it unless your behind the wall, so it works very well.


Thank you! 

Ordered up today, cheapest fabric also, as its hidden, same as yours, no need to go overboard!


----------



## nitro28

BllDo said:


> GOM would work fine. It's a little pricey for this use though. I used black speaker cloth from Rose Brand. Cheaper and still fire rated.
> 
> http://www.rosebrand.com/product800/102-Black-Speaker-Cloth-FR.aspx?tid=2&info=speaker+cloth


Does that speaker cloth have any sheen to it, or is it pretty light absorbing? I have seen some speaker fabrics that seem to have a little sheen. I'm trying to decide between black GOM for my columns and speaker cloth. Rosebrand is half the price. Thanks.


----------



## BllDo

nitro28 said:


> Does that speaker cloth have any sheen to it, or is it pretty light absorbing? I have seen some speaker fabrics that seem to have a little sheen. I'm trying to decide between black GOM for my columns and speaker cloth. Rosebrand is half the price. Thanks.


IIRC it's pretty flat. I know what you are talking about with the shiny grill fabric. I don't remember this having that quality at all. I used the speaker cloth to cover the insulation on the wall behind my screen, and GOM for the fabric panels around my screen. I think the biggest difference between the two is that GOM is generally a little bit thicker than the speaker cloth. At least FR-701 is. I have Sensa as well. That one is a bit of a toss up as far as I remember. Well, that and that GOM is available in colors other than black. Thicker fabric would be more important if you are concerned about light bleeding through the fabric. GOM also has very good and well documented acoustic attenuation properties. I don't think that the speaker cloth has been put the those same tests, but being that it's a bit thinner than GOM I would imagine that it would be similiar or better in terms of treble loss. 

If you are constrained by budget and/or are not concerned about light bleed, the Rose Brand speaker cloth is pretty good stuff for the money plus it's still FR unlike normal fabric from the craft store. However if you have the budget, I would recommend GOM over speaker cloth for any place that appearance might be a concern or you are one of those strange people that want something other than black. Hope that helps.


----------



## CHILINVLN

As far as controlling sound, rattles, and vibration, has anyone encountered their screen rattling at times? I find myself constantly making adjustments and shoving foam between the screen and the metal track trying to find a way to resolve it. Doesn't happen often, but when I hear it rattle, it's very annoying. I appreciate any suggestions from folks who may have had a similar problem.

I have a 110" Fixed DragonFly Screen


----------



## airliner

*New theater*

Hi all, first post in this fantastic and loong thread.
I am Marco, I am from Italy, and I have a sickness for audio video etc etc.
Most of my friends knows it and always came and ask.
Last one want to build a theater in his bunker, yes a concrete bunker.
I've been trying to learn as much as possible.
I wanted to build a theater 5m by 7m, height is variable, 2,1m in the first part, then 2,9m. Planning to make 9.2.6, is it possible?
6 would be 2 ceiling mounted and 4 reflecting, what would you use as a material where you expect the reflection of the atmos module?
Then I have tousand more of question but I think it is enough as a start.
Marco.


----------



## billqs

I'm back. Been busy selling my old speakers and getting the M&K 150's set up. I'm leaning heavily on placing a thick insulation like an R30 and place around the perimeter of the room on top of the ceiling tiles, though again, I hate getting into the tiles. Still would be less work than lining the entire ceiling with it. Is R30 thick enough? It appears like it would be. I've taken care of my high frequency problem with Acoustic blankets, so I don't really want more high frequency absorbsion. I believe having the ceiling tiles as a barrier would prevent highs from becoming further attenuated.

I put a drawn out image of my room about a page back. It's 10 x21x8 to drop ceiling. I'm thinking I'd get similar response to soffit mounting by placing the thick fiberglass on top of the perimeter tiles, plus the traps would be out of the way of the floor. It seems like a good first start. As I mentioned before, I have real trouble doing floor to ceiling traps in corners due to my layout. 

It's not that I'm noticing bad sound, it's just a warmer sound because the highs no longer have room gain and echoes. My two subs help regulate peaks and nulls and are not on the boomy side, though the Boston Acoustics 12" is not in the same caliber as my SVS sub I use up front. My main goal I guess is to shorten time durations after signals leave the subwoofer so that they become more distinct and don't bleed over other sounds.

Is my solution sound? (no pun intended.) I figure I can supplement with some limp membrane traps if needed as they can go up against the wall.


----------



## Wildbrando

Nice


----------



## billqs

So, I'm off to buy the fiberglass for perimeter placement above my ceiling tiles. I have a choice of R38 16 inches wide or R30 24" wide. Which would be better?


----------



## AidenL

Can I just clarify something? 

Is it correct that ordinary fibreglass rolls are better for Superchunk traps than rigid Rockwool slabs?

It's a lot cheaper if so. I thought denser Rockwool would be better?


----------



## HopefulFred

The story is that when thicker than 6", lower gas flow resistivity material is more effective at low frequencies. So, yes: loose fiberglass batts will be more effective bass traps than something like 6pcf fiberboard will be.


----------



## AidenL

HopefulFred said:


> The story is that when thicker than 6", lower gas flow resistivity material is more effective at low frequencies. So, yes: loose fiberglass batts will be more effective bass traps than something like 6pcf fiberboard will be.


That's a pleasant surprise. I have some Rockwool left over, but I'll get another use for it.

I'll buy two rolls of fibreglass today.


----------



## BamaDave

I understand the need for absorption, diffusion as well as bass traps but since I have crossed over to atmos my thinking is somewhat fussy now. With this new format the front three speakers don't seem to be much more driven than the balance, well not quite as much as they were before. I'm planning on adding some panels but now I'm somewhat waiting to see what the experts think about placement. Should I set absorption panels at the front three speaker 1st reflections points as previously recommended? Can someone weigh in on this topic, please?


----------



## billqs

I'm ::so:: not an expert, but I would think ideally you would want to to absorb first reflections from all channels. With Atmos that can be anywhere from 9 to 13 channels. That's one reason I decided to treat my entire room above ear level. 

If you can't do this, then I believe the frontstage is still the most important to treat. Remember that first reflections hit the ceiling and floor as well as the side walls, and there can be some scatter if your room is narrow (like mine is.) 

Why not start with treating the first reflections from your frontstage and see how you like the results. If you like them, then you can add more treatment later.


----------



## asoofi1

Can someone tell me if a riser made as a bass trap would negate having to install corner traps as well? Sealed room.


----------



## billqs

Well there's not really any information you've posted on your room so it's hard to say...


----------



## Mfusick

asoofi1 said:


> Can someone tell me if a riser made as a bass trap would negate having to install corner traps as well? Sealed room.


Depends on the riser you build and the room problems you want to fix


----------



## bflip1080

I'm too lazy to look up rules on posting prices and sites so i will stay vague.

If anyone is looking for 2" Auralex wedge 2'x4' panels, there is a sale at massdrop ending soon that saves almost $300 from the current amazon price.

i have been looking for a discount on treatment panels for a long time, and this seems to be a rare one. just thought i'd share. hopefully it doesnt get me in trouble with the mods.


----------



## yngdiego

bflip1080 said:


> I'm too lazy to look up rules on posting prices and sites so i will stay vague.
> 
> If anyone is looking for 2" Auralex wedge 2'x4' panels, there is a sale at massdrop ending soon that saves almost $300 from the current amazon price.
> 
> i have been looking for a discount on treatment panels for a long time, and this seems to be a rare one. just thought i'd share. hopefully it doesnt get me in trouble with the mods.


Stupid question, but what's the best way to use these? I'm planning on 2" insulation triangles stacked in the corners for bass traps. And 2' x 4' x 2" covered insulation at the first reflection points. Where would I use these panels?


----------



## bflip1080

yngdiego said:


> Stupid question, but what's the best way to use these? I'm planning on 2" insulation triangles stacked in the corners for bass traps. And 2' x 4' x 2" covered insulation at the first reflection points. Where would I use these panels?







good info here in this vid. 

you could use these instead of the covered insulation at thefirst(or mirror) reflection points or behind the speakers for early reflections.


----------



## sigma722

So, I'm pretty far from theater completion, but is it a good idea to buy into that drop? 

It seems like most people just use some sort of insulation covered with fabric for absorption. Then besides that, they use diffusion of some kind to treat in other ways. 

My theater will be something like 14'x22'8', so I'm trying to determine if it's good to just get a set. 

I haven't gotten far enough in my build to really research the sound treatment aspect yet, so I'm really out of my depth here.


----------



## dnoonie

sigma722 said:


> So, I'm pretty far from theater completion, but is it a good idea to buy into that drop?
> 
> It seems like most people just use some sort of insulation covered with fabric for absorption. Then besides that, they use diffusion of some kind to treat in other ways.
> 
> My theater will be something like 14'x22'8', so I'm trying to determine if it's good to just get a set.
> 
> I haven't gotten far enough in my build to really research the sound treatment aspect yet, so I'm really out of my depth here.


I've tried acoustic foam and although it has it's uses (I'll be putting foam corner bass absorber back into the horizontal corners of my freshly updated theater) I prefer insulation filled panels.

Why insulation filled panels:


It's easier to fill a couple small holes with Spackle and repaint than it is to clean off glue then repaint. Glue is not that easy to clean off.
Panels are more efficient, yes they're more expensive but if you consider NRC figures between the two the cost ends up being about the same for the NRC values.
I've found hanging panels more fool proof and easier than gluing foam. I've had glue failures but have not had panel mount failures. Hanging panels is as easy as hanging a picture frame. My glue failures were due to the unevenness of the walls in my 50YO house, if your walls are more even than mine you would have better luck with glue than I did.
NRC shaping. Different materials have different NRC graph shapes. Use the material that works best for the frequencies that need tamed.
Why Acoustic Foam:


Cost effective if you can put up with the glue and don't need additional absorption power.
NRC shaping. Different materials have different NRC graph shapes. Use the material that works best for the frequencies that need tamed. I'm using the foam bass absorbers because of their even response down through the low frequencies, fiber glass and rock wool bass panels tend to have peaks and I needed something more even. But I'm not gluing them again. After using fiberglass filled bass panels in vertical corners and the back wall I had a pretty even room response so the foam fit the spec.
Auralux ships uncompressed, probably because it's made, warehoused and then shipped. It makes it expensive to ship because of it's bulk.


I got my foam bass absorbers from The Foam Factory,http://www.thefoamfactory.com/acousticfoam/acousticfoam.html


It takes a week or two for them to ship because they're made to order but they ship vacuum compressed so shipping is ultra inexpensive and a lot safer, they shipped my order of 10 24" x 12" bass absorbers wrapped in 3 layers of cardboard, it was shaped like a 19" around football when it arrived, the first layer of cardboard was cut through in places due to abusive handling but the product was completely safe. The foam must be un-packaged and allowed to expand as soon as possible, it can take 12 to 48 hours for it to expand. *It can not be stored in it's compressed shape!! *Make sure you have time for the order to come and space for the foam to decompress and be careful not to cut the foam when you unwrap the stuff.



Cheers,


----------



## jimmy19794

JBS said:


> OK, this seems straightforward from searching AVS and studying theater wall treatment...
> 
> 
> FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.
> 
> CEILING: No acoustical treatment - none, nada.
> 
> FLOOR: Thick, plush carpet is fine.
> 
> 
> But here's where it gets confusing, and I need help...
> 
> 
> SIDEWALLS
> 
> A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.
> 
> --or--
> 
> B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.
> 
> 
> These 2 theories seem to contradict each other. So which is it?
> 
> 
> 
> BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:
> 
> 
> Owens Corning Select Sound Black Acoustic Board
> 
> Owens Corning Fiberglas 703 Series duct insulation.
> 
> Johns Manville Insul-Shield
> 
> Johns Manville Linacoustic Permacoate rolls.
> 
> Certainteed Certpro Acoustaboard Black
> 
> Knauf Duct board EI-475
> 
> Knauf Duct liner EM
> 
> 
> ...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.


make!come to here again thks!


----------



## nickbuol

For your posters, you could have them reprinted on fabric and then be acoustical panels...

http://www.avsforum.com/forum/19-de...inted-movie-poster-acoustic-panels-cheap.html

The early users of this printing service have fairly washed out images, the print and color quality is excellent now.


----------



## dnoonie

Molon_Labe said:


> I need some advise from those who have experience with poor rooms and treatments.


Generally it's best to treat first and second reflection points and vertical corners with bass traps first. That being said... 

First.
Your horns are a great help as far as first and second reflection points. How is your stereo imaging? Have you heard a good stereo setup with good imaging? *If *you're happy with your stereo imaging I'd skip first and second reflection treatment (you might not have any with those horns, except for your center channel). The first go around I'd just treat corners with bass traps.*(If not see below) Build 4 inch thick panels and treat your vertical and diagonal corners as best you can. Then I'd test to see what offending frequencies are present. My guess would be that you still have bass issues but you need to find out what frequencies they're at, if they're around 80Hz to 125Hz or so I'd move the 4 inch panels to horizontal corners where they intersect diagonal corners and put in some 6" vertical bass absorbers. Measure again. Still have bass issues? Build some more bass absorbers to treat the proper frequencies and put them on the back wall. For your proposed horizontal corner absorbers I'd make 4 inch, I think it's more important to treat vertical corners and corner intersections first though.

Second.
Does your center channel have "imaging" or first reflection issues? Check with a mirror. Get a cheep full height, made of flexible metal mirror and check your center channel reflection points at your MLP. It could very well be behind the MLP and not an issue.

Third.
If your stereo pair doesn't have first or second reflection point issues because of the horns then...break of modes. Your testing should have shown frequency issues in the higher ranges. You don't need symmetrical or full coverage to treat modes you just need to break them up. You can alternate left/right coverage with gaps. I really like the printed fabric poster idea!!! You can use 1 inch or 2 inch depending on the frequencies you need to treat, 1 inch are good to about 600Hz, 2 inch is good to about 350Hz.

*
First and second reflection points. If you do have issues in this regard try angling your speakers to eliminate them. If they persist then use an unbreakable mirror to find first and second reflection points and treat them, including the ceiling and diagonal walls.

Cheers,


----------



## dnoonie

Molon_Labe said:


> Thanks for the detailed response. Previously, I only had two JBL4722's upfront with a TV in the middle. The imaging was fine, and I was running without any EQ. My receiver has Audyssey but I felt it really nurtured the JBLs, so I didnt use it. I have since sold the TV and decided to go projector and have bought the center 4722. My rear speakers are the same as the front three so I have horns all the way around in a 5.2 setup. I also bought Dirac Live (miniDSP DDRC-88a) for EQ and a dual core anti-mode for the subs. I am sure between the two it will clean things up nicely but I would like to treat the room first and then use the digital effects to smooth out the bumps in the road. The horn do focus the sound nicely and even without EQ or treatments the room didnt sound bad, but I know it can be better. Pardon my ignorance, but how do I use a full size mirror to find the reelection points?


Nice that the horns are effective!!

For using a mirror to find reflection points check this video about 2:10 in, 



. Watch the whole video if you'd like, it's pretty good.
Keep in mind that this technique does not consider the use of your horn arrangement. That horn is 90 degree, so if it's angled 45 degrees or a bit more from the wall then there shouldn't be an issue. If you think you might have an issue, experiment with speaker angle, speaker placement and or listening position to see if the sound can be improved. You might find a more ideal position but it might not work for other reasons, like screen placement, but at least you know the sound can be improved and treatment will likely help. If you think you can improve the sound with some absorbers then try some treatment there, you can always move treatment to a location where you can use it to break up modes if it doesn't make a difference, assuming you haven't built too many panels.

Cheers,


----------



## wse

dnoonie said:


> Nice that the horns are effective!!
> 
> For using a mirror to find reflection points check this video about 2:10 in, https://www.youtube.com/watch?v=B9u7k2V4YPw. Watch the whole video if you'd like, it's pretty good.
> Keep in mind that this technique does not consider the use of your horn arrangement. That horn is 90 degree, so if it's angled 45 degrees or a bit more from the wall then there shouldn't be an issue. If you think you might have an issue, experiment with speaker angle, speaker placement and or listening position to see if the sound can be improved. You might find a more ideal position but it might not work for other reasons, like screen placement, but at least you know the sound can be improved and treatment will likely help. If you think you can improve the sound with some absorbers then try some treatment there, you can always move treatment to a location where you can use it to break up modes if it doesn't make a difference, assuming you haven't built too many panels.
> 
> Cheers,


Many always forget the ceiling!


----------



## stef2

wse said:


> Many always forget the ceiling!



I just rechecked my ceiling's first reflection points (for L, C and R channels), then moved some absorption panels from the back of my HT to the ceiling to cover those. Imaging has clearly improved!


----------



## grendelrt

How would absorption panels affect in ceiling speakers for Atmos, for example how close and thick could a panel be to a speaker without interfering with its output?


----------



## erwinfrombelgium

grendelrt said:


> How would absorption panels affect in ceiling speakers for Atmos, for example how close and thick could a panel be to a speaker without interfering with its output?


I think with in ceiling speakers you should stay the absorber thickness away or else use 45° edges on the absorbers if you DIY.


----------



## grendelrt

45 degrees, interesting, thanks! 

Sent from my SCH-I535 using Tapatalk


----------



## digitlman

I am looking for any opinions as to wether or not I am doing my acoustic treatments properly for my room. It is 16x21 and this is a rough rendering of where we are planning on putting 4x2 and 2x2 GoM wrapped 2" thick OC703 panels. I am also planning on making a 2D skyline diffusor for my first reflection point and am unclear if I am doing that right. I know and understand only a little bit about how it works but understand it is frequency based. I am however trying to build it from my desired size and and the calculator ends up with whatever frequency range it does and I will have to live with that. But is it good and going to work right? I just want my B&W 802's to sound as good as they can for 80% movie 20% music.
I want to use 2x2 blocks but they are actually 1.375 inches, I converted to metric and end up with this:

http://www.mh-audio.nl/DiffusorCalculator3.asp?km=3.492&kl=10&calc=Calculate+Diffuser#result

If I put this together, 2 X wide and 3 X high for a combined size of a 33" X 49.5" diffusor panel will this give me good results for my 1st reflection? 

My front wall around my screen will be covered with OC703 and I am going to stack triangle cuts for bass traps in the corners from 12" pieces. I am thinking about 42" high for them. 

Also Do i need to make any consideration for my back left corner dorway, it ended up being a 2ft deep X 4ft Wide "nook" essentially and will this cause any issues with my sound and need any special treatments?










Thanks!


----------



## Naylorman32

I know this has probably been answered numerous times in this thread, but if i wanted to purchase some pre-made bass traps (both corner and wall), where would you guys recommend I shop? Shipping from online retailers is a killer, so i'd love to avoid that. I previously purchased a pair of acoustic panels on Amazon. 

Thanks!


----------



## cesar123

Naylorman32 said:


> I know this has probably been answered numerous times in this thread, but if i wanted to purchase some pre-made bass traps (both corner and wall), where would you guys recommend I shop? Shipping from online retailers is a killer, so i'd love to avoid that. I previously purchased a pair of acoustic panels on Amazon.
> 
> Thanks!


GIK Acoustics, IMO, is a great option. I don't think their shipping charges are too much, and they have good products _and_ customer service.


----------



## dnoonie

Naylorman32 said:


> I know this has probably been answered numerous times in this thread, but if i wanted to purchase some pre-made bass traps (both corner and wall), where would you guys recommend I shop? Shipping from online retailers is a killer, so i'd love to avoid that. I previously purchased a pair of acoustic panels on Amazon.
> 
> Thanks!


I've ordered from:
http://www.atsacoustics.com/
http://www.acoustimac.com/

Some day I'll likely order from GIK as well...

I was very happy with their service. I'd pick the one that's closest to where they're being shipped.

Cheers,


----------



## myfipie

cesar123 said:


> GIK Acoustics, IMO, is a great option. I don't think their shipping charges are too much, and they have good products _and_ customer service.


Thanks for the recommendation. I always recommend contacting us through our room set up page so we can help you with picking the right products.
http://www.gikacoustics.com/acoustic-advice/


----------



## sigma722

myfipie said:


> Thanks for the recommendation. I always recommend contacting us through our room set up page so we can help you with picking the right products.
> http://www.gikacoustics.com/acoustic-advice/


It seems like a lot of your diffusors are out of stock. Does that happen often?


----------



## myfipie

sigma722 said:


> It seems like a lot of your diffusors are out of stock. Does that happen often?


The QRD is being faded out due the the new poly, which is much better value and we just got back ordered on the Q7D yesterday.  Hoping that should only be a few days. Those have been selling like hot cakes as of late.


----------



## batlin27

I have a question for everyone on the insulation to use on my rear wall

I am going to have 4 inch Panels covering my back wall to take care of the rear wall reflections. I know that it would be best to have much larger / thicker panels but 4in is as big as I can go.

I have 2 options for the insulation

Roxul Safe and Sound 3" with a 1" Air Gap 
PRODUCT THICKNESS DENSITY	125HZ 250HZ	500HZ	1000HZ 2000HZ 4000HZ NRC
Safe‘n’Sound	3" 2.5 pcf 0.52 0.96 1.18 1.07 1.05 1.05 1.05

Or 
MinWool-1200 Industrial Board 1280 2" with a 2" Air Gap
PRODUCT THICKNESS DENSITY	125HZ 250HZ	500HZ	1000HZ 2000HZ 4000HZ NRC
MinWool 1280	2" 8 pcf 0.32 0.90 1.11 1.07 1.01 1.05 1.00


Thoughts?


----------



## myfipie

batlin27 said:


> I have a question for everyone on the insulation to use on my rear wall
> 
> I am going to have 4 inch Panels covering my back wall to take care of the rear wall reflections. I know that it would be best to have much larger / thicker panels but 4in is as big as I can go.
> 
> I have 2 options for the insulation
> 
> Roxul Safe and Sound 3" with a 1" Air Gap
> PRODUCT THICKNESS DENSITY	125HZ 250HZ	500HZ	1000HZ 2000HZ 4000HZ NRC
> Safe‘n’Sound	3" 2.5 pcf 0.52 0.96 1.18 1.07 1.05 1.05 1.05
> 
> Or
> MinWool-1200 Industrial Board 1280 2" with a 2" Air Gap
> PRODUCT THICKNESS DENSITY	125HZ 250HZ	500HZ	1000HZ 2000HZ 4000HZ NRC
> MinWool 1280	2" 8 pcf 0.32 0.90 1.11 1.07 1.01 1.05 1.00
> 
> 
> Thoughts?


Fiberglass or mineral wool absorbs more than air so 3" with 1" gap.


----------



## batlin27

myfipie said:


> Fiberglass or mineral wool absorbs more than air so 3" with 1" gap.


Awesome thank! This will save me some cash


----------



## raynist

I am going to build some acoustical treatments and will be using the 5.5 inch ultratouch denim as my insulation material. To keep dust at bay I was planning on wrapping it with some material. I found this on Amazon:

http://www.amazon.com/Singed-Polyester-Filter-Fabric-Micron/dp/B004JH9EUW

It should not let anything greater than 1 micron out. I think it is felt. I wonder this would work or if it would be to reflective?


----------



## HopefulFred

I'm leaning toward too reflective - also too expensive. Of course, too reflective is a relative status... maybe you need too reflective?


----------



## artur9

raynist said:


> I am going to build some acoustical treatments and will be using the 5.5 inch ultratouch denim as my insulation material. To keep dust at bay I was planning on wrapping it with some material. I found this on Amazon:
> 
> http://www.amazon.com/Singed-Polyester-Filter-Fabric-Micron/dp/B004JH9EUW


Coupla weeks back someone recommended this speaker cloth.

I'm also intending to use that Ultratouch (have some on order) because we want to keep the rock wool away from the kids. There's this one panel they (well, one) have taken to leaning on.


----------



## raynist

HopefulFred said:


> I'm leaning toward too reflective - also too expensive. Of course, too reflective is a relative status... maybe you need too reflective?


They sell 5 yards of if for 60 ish. That would be enough to do all of my panels.


----------



## bgtighe23

Naylorman32 said:


> I know this has probably been answered numerous times in this thread, but if i wanted to purchase some pre-made bass traps (both corner and wall), where would you guys recommend I shop? Shipping from online retailers is a killer, so i'd love to avoid that. I previously purchased a pair of acoustic panels on Amazon.
> 
> Thanks!


I purchased mine from ATS Acoustics on Amazon. I was unfamiliar with Gik at the time I purchased the ATS panels.

I can't say which is more potent at sound absorption, but I can say that ATS is slightly cheaper, and the Microsuede fabric option is very decorative. They look really great.


----------



## BllDo

raynist said:


> I am going to build some acoustical treatments and will be using the 5.5 inch ultratouch denim as my insulation material. To keep dust at bay I was planning on wrapping it with some material. I found this on Amazon:
> 
> http://www.amazon.com/Singed-Polyester-Filter-Fabric-Micron/dp/B004JH9EUW
> 
> It should not let anything greater than 1 micron out. I think it is felt. I wonder this would work or if it would be to reflective?


I use this material for filter socks for my aquarium. It's thick and would definitely be reflective of higher frequencies. Honestly though, you are way over thinking this. The fabric you cover the treatments with will keep most fibers from getting out. Ultratouch is nice stuff. It's not like fiberglass insulation. 
You could completely wrap the treatments in speaker cloth for some extra protection, but I would not use this material unless you are strictly looking for bass trapping.


----------



## bgtighe23

How worth it is it to invest in panels?

I mean, how much does the price of covering the 1st reflection points of your HT compare to the ratio of gained sound quality?

Are panels really something that should be invested in, or should the $500 (approx.) be invested in other areas like getting a $500 better sub? 

(not a $500 sub, but adding $500 to the "sub budget")


----------



## cesar123

^^

Well, according to our great writers at AVS, it's ranked at #2 : http://www.avsforum.com/forum/301-avs-forum-articles/2100490-10-ways-improve-your-sound-system.html

"2. Improve room acoustics—the room is a part of your system. Use sound absorbing and diffusing materials to tune your listening space. Add a rug between your seat and the speakers. Hang drapes in front of large windows. Bass traps help tame the peaks and nulls known as room modes."

I've invested money and time into room acoustics (DIY panels and ready-to-go bought panels). In my opinion, VERY worth it.


----------



## erwinfrombelgium

bgtighe23 said:


> How worth it is it to invest in panels?
> 
> I mean, how much does the price of covering the 1st reflection points of your HT compare to the ratio of gained sound quality?
> 
> Are panels really something that should be invested in, or should the $500 (approx.) be invested in other areas like getting a $500 better sub?
> 
> (not a $500 sub, but adding $500 to the "sub budget")


Interesting that you compare to "sub budget". As Floyd Toole and other authorities have demonstrated time and again: below the transition frequency (250-300Hz or there about, depending on room size, so that's sub territory), the sound is dominated by the room, not by the speaker. So $500 for the room spent wisely might be worth more than $5000 of subs...


----------



## artur9

bgtighe23 said:


> I mean, how much does the price of covering the 1st reflection points of your HT compare to the ratio of gained sound quality?


I always like to know the objective. 

In my case adding absorption really improved dialogue clarity which I value highly. 

But if you like movies with lots of depth charges in them then buying a more powerful subwoofer may be the right way to go.


----------



## HopefulFred

bgtighe23 said:


> Are panels really something that should be invested in, or should the $500 (approx.) be invested in other areas...


As with most things - that depends. But there are things you can do with treatment that cannot be done within the six surfaces of a room by other means. So, if you have to prioritize (as we all do at some point), you pick your poison based on your needs.


----------



## dnoonie

artur9 said:


> I always like to know the objective.
> 
> In my case adding absorption really improved dialogue clarity which I value highly.
> 
> But if you like movies with lots of depth charges in them then buying a more powerful subwoofer may be the right way to go.


If you like your bass to be more distinctive (clearly hear the difference between bass guitar and kick drum and low synth FX) with bass clarity then room treatment might be for you.

You can save money by purchasing a full room kit rather than individual panels.

Hope you get a balanced setup the way you like it!

Cheers,


----------



## myfipie

bgtighe23 said:


> How worth it is it to invest in panels?
> 
> I mean, how much does the price of covering the 1st reflection points of your HT compare to the ratio of gained sound quality?
> 
> Are panels really something that should be invested in, or should the $500 (approx.) be invested in other areas like getting a $500 better sub?
> 
> (not a $500 sub, but adding $500 to the "sub budget")


You can hear for yourself a room treated vs untreated. I recommend you use headphones if your room is untreated. 
http://www.gikacoustics.com/audio-examples-treated-vs-untreated-room/


----------



## artur9

myfipie said:


> You can hear for yourself a room treated vs untreated. I recommend you use headphones if your room is untreated.
> http://www.gikacoustics.com/audio-examples-treated-vs-untreated-room/


That's quite an extreme example! But the treated room seems a little too dead. Can you explain a bit about why you choose to dampen it as much?


----------



## blazar

To me, Highly absorptive rooms would primarily be useful for multichannel setups in which all reverb etc is simulated by the channels or some dsp.

This type of room will also tend to make you feel sleepy just like a dark room. A dark and absorptive room is essentially a sensory deprivation chamber.

I am much happier with a brighter room, sunlight allowed to come in with motor shades, and mostly diffusive surfaces.


----------



## myfipie

artur9 said:


> That's quite an extreme example! But the treated room seems a little too dead. Can you explain a bit about why you choose to dampen it as much?


Actually the decay is still above 300ms which is considered pretty alive. If anything I would have added more, but as much as using a mic to show a before and after is helpful, it does sound different when in the room listening with human ears.


----------



## Mfusick

blazar said:


> To me, Highly absorptive rooms would primarily be useful for multichannel setups in which all reverb etc is simulated by the channels or some dsp.
> 
> This type of room will also tend to make you feel sleepy just like a dark room. A dark and absorptive room is essentially a sensory deprivation chamber.
> 
> I am much happier with a brighter room, sunlight allowed to come in with motor shades, and mostly diffusive surfaces.


I find envelopment a more critical component of 2 channel and music.

I do agree to some extent that a multi channel based movie room can be more dead and still work well. But those rooms kind of suck the life out of music. 

Absorption is probably overused a lot in the dedicated theater builds because it's easily understood, cheap, and easy to do. It takes a little more to do diffusion well. But balance them is where you get the sparkle in a room.


----------



## bgtighe23

blazar said:


> To me, Highly absorptive rooms would primarily be useful for multichannel setups in which all reverb etc is simulated by the channels or some dsp.
> 
> This type of room will also tend to make you feel sleepy just like a dark room. A dark and absorptive room is essentially a sensory deprivation chamber.
> 
> I am much happier with a brighter room, sunlight allowed to come in with motor shades, and mostly diffusive surfaces.


I have several 2" panels around the room. I have 1 behind each speaker, and on each wall to the side of the left and right speaker.

So I have 5 panels for my front 3 speakers 
I have 1 panel behind each surround speaker, so add 2 (5.2 setup)
and 2 panels directly behind the LP - So 9 total.

Most of the panels are 24x24x2 except the panels for the Left and Right speakers; those are 24x48x2 (x4)
I noticed quite a big difference pre and post panels. That noticeable echo from my light colored bare walls were really minimized.
I've heard the bit from GIK acoustic with the audio with/without panels and my room was never _that_ bad. I'm sure someone's room does sound like that, but good marketing to them nonetheless. My room sounds much smoother and the speakers have a little more airiness to them. They seem to breathe a little more also.

The room looks a little more complete with the panels because the walls aren't so bare anymore. And I was able to tuck my HDMI and power cord from my wall mounted tv behind the center channel's panel - Though the cords still noticeable, the panels really serve multiple purposes and really add some nice decor to the room. I also didn't want to put a couple holes in the wall either 


I sold some speakers to someone in Austin, TX who had over 30 panels, none of which were greater than 4" thick, or on the ceiling, and also no diffusion or bass traps. It was a little crowded feeling.


----------



## AXLCMT

*OC703 - 1" deep 4' x 8' or 2' x 4' Sheets?*

I plan on putting the usual OC703 on my side walls and front corners bass traps and the side walls up to 42" high (ear height).

The one side wall is 23 feet long and the other is 16 feet long.

Does it matter whether I buy the OC703 4' x 8' or 2' x 4'? 

Does it make a difference?


----------



## dnoonie

Mfusick said:


> I find envelopment a more critical component of 2 channel and music.
> 
> I do agree to some extent that a multi channel based movie room can be more dead and still work well. But those rooms kind of suck the life out of music.
> 
> *Absorption is probably overused a lot in the dedicated theater builds because it's easily understood, cheap, and easy to do*. It takes a little more to do diffusion well. But balance them is where you get the sparkle in a room.


Yes, that's why I choose absorption over diffusion 2 years ago. Now that I'm doing some evolutionary improvements I'm taking out some absorption and putting in some diffusion. It's more than a little more difficult in a 12' wide room, when I'm replacing something that's 2" thick with something 7 inches thick it takes considerable space away from the walkway and/or seating so I'm not placing diffusion in locations I could (when I change my seating I'll reconsider), consequently my room will sound a lot dryer than I'd like but that's the way it goes. Maybe in 3 or 4 years I'll be able to build a new room that's large enough to have a more lively sound but for now...

I could custom build some thinner diffusion over 1' absorption but simply don't have the time and can't afford to purchase, so yes it can be done it's simply too difficult or too expensive for me to do at the moment.

Another option would be ceiling mount for diffusion but truss locations don't accommodate easy hanging so I'd need time to do the rigging myself or hire it done if I used the QRDs, no time or $ for it now, maybe in December or January. Actually the GIK Polyfusor would be a great candidate for that location where my ceiling meets the back wall, at only 20lbs I might be able to cantilever it like I'm doing the absorbers there now. The room entrance is in the back wall which limits placement but I've managed to ceiling/corner hang 2'x4' absorbers there now using a combo of truss (holds 3/4 of the weight) and picture frame hooks so a Polyfusor may hang there just as easy.

Cheers,


----------



## blazar

3d surfaces simply translate into higher cost than absorptive surfaces, but I find the results more pleasing.


----------



## myfipie

AXLCMT said:


> I plan on putting the usual OC703 on my side walls and front corners bass traps and the side walls up to 42" high (ear height).
> 
> The one side wall is 23 feet long and the other is 16 feet long.
> 
> Does it matter whether I buy the OC703 4' x 8' or 2' x 4'?
> 
> Does it make a difference?


The size does not matter as much as the thickness. Honestly if you can I would use no less than 4" on wall and get bass trapping in the corners.


----------



## myfipie

> Absorption is probably overused a lot in the dedicated theater builds because it's easily understood, cheap, and easy to do. It takes a little more to do diffusion well. But balance them is where you get the sparkle in a room.


I agree 100% on the diffusion, but what I mostly see is rooms with the wrong kind of absorption. Using just 2" fiberglass throughout the room is going to kill the upper frequencies, and leave the low end bouncing around. With the proper trapping the low end will become much tighter/focused. There is a reason we designed a lot of our trapping with limiters. It absorbs only below 400hz which is always welcome in smaller rooms or we use a built in scatter plate to diffuse/scatter the upper frequencies in the room. 
http://www.gikacoustics.com/flexrange-technology-bass-trap/
Many ways to skin a cat, but a lot absorption can be your friend, if used properly.


----------



## asoofi1

myfipie said:


> I agree 100% on the diffusion, but what I mostly see is rooms with the wrong kind of absorption. Using just 2" fiberglass throughout the room is going to kill the upper frequencies, and leave the low end bouncing around. With the proper trapping the low end will become much tighter/focused. There is a reason we designed a lot of our trapping with limiters. It absorbs only below 400hz which is always welcome in smaller rooms or we use a built in scatter plate to diffuse/scatter the upper frequencies in the room.
> http://www.gikacoustics.com/flexrange-technology-bass-trap/
> Many ways to skin a cat, but a lot absorption can be your friend, if used properly.


Would building a raised seating platform as a bass trap eliminate the need to have corner bass traps? Or I should say, could the platform trap perform the same way as corner traps?

My room is a closed 20Lx16W...just fyi.


----------



## Mfusick

asoofi1 said:


> Would building a raised seating platform as a bass trap eliminate the need to have corner bass traps? Or I should say, could the platform trap perform the same way as corner traps?
> 
> My room is a closed 20Lx16W...just fyi.


Bass trap riser can help tame standing wave problems but you need to locate it and the vents near a boundary so it's not applicable for every room or situation. 

You can also make your riser tuned to help at certain frequencies; it's called a helmholtz resonator. Think like when you blow across a bottle top... Except in this case you tune it to help at a certain place you need it. That's not acoustics 101 topic though.


----------



## Mfusick

blazar said:


> 3d surfaces simply translate into higher cost than absorptive surfaces, but I find the results more pleasing.


I'm generally not a fan of sensory deprivation chambers either . That's what a lot of diy theaters become when people go overboard with basics. Less is more. Same goes for killing light. I was in a theater that was pitch black, everything was black. It was awful.


----------



## dnoonie

Mfusick said:


> I'm generally not a fan of sensory deprivation chambers either . That's what a lot of diy theaters become when people go overboard with basics. Less is more. * Same goes for killing light. I was in a theater that was pitch black, everything was black. It was awful*.


So color grading rooms are painted 18% neutral grey. What would the acoustic equivalent be? For audio it seems like there are guidelines for reverb time, flatness of the room response and varying methods of getting there either through absorption, diffusion, room design, EQ, speaker placement, speaker design, etc. depending on personal preference. People don't typically listen or mix in an anechoic chamber.

Here'$ a live one!$$. No doubt it sounds great! And very pretty too!










Cheers,


----------



## Mfusick

That seems like a lot ^. Lol!

I think a lot of mastering studio tend to be a bit more on the dead side. But some reflections can add envelopment and spaciousness. You never want to kill them all; you only want to diminish the bad ones or the sound power to the point they are not a problem. If you listened to music in an anechoic chamber it would NOT sound good (natural).


----------



## dnoonie

Mfusick said:


> That seems like a lot ^. Lol!
> 
> I think a lot of mastering studio tend to be a bit more on the dead side. But some reflections can add envelopment and spaciousness. You never want to kill them all; you only want to diminish the bad ones or the sound power to the point they are not a problem. If you listened to music in an anechoic chamber it would NOT sound good (natural).


Here's a better pic, I think someone at Blackbird Studios likes skyline diffusion.









It's Blackbird Studios and I would guess calculate that those skyline diffusion ( http://www.mh-audio.nl/DiffusorCalculator.asp?fl=300&fh=3500&calc=Calculate+Diffuser#result*) *go down to around 300Hz. A lot of work, a lot of weight if they're solid wood.

Cheers,


----------



## ctviggen

That is really cool, but has negative wife acceptance factor. ;-)


----------



## AllenA07

I'm asking questions that I'm sure are asked elsewhere here, but considering there are nearly 11,000 posts I've got little hope of finding an answer. I've recently moved into a new house and have my first real dedicated theater. I'm thinking that acoustical treatments are going to be my next upgrade and I'm trying to figure out where I want to start. My research has lead me to thinking bass traps might be the way to start (along with treating the first reflection points). With bass traps how much is that going to change ability to hit the ULF? Right now I've got dual SVS subs (corner loaded) and have usable bass to just north of 12hz. I don't really want to lose my ability to play that low by taming room modes. On the subject of bass traps, my initial plans would not have floor to ceiling bass traps. Right now I'm looking with some interest at the GIK room kit 3, which would give me 4 traps, one for each corner plus make some headway on those first reflection points. Are traps still worth it if I'm not going to have floor to ceiling. Finally with bass traps, how much do they help control peaks and nulls? I assume the end game here is a flatter response, I just am not sure what I should be expecting.

In terms of treating the room, my only other concern is using my bipole side surrounds. Those speakers depend on reflections to work, so wouldn't treating the room render them pointless?

Again, I know that most of these question are pretty basic, but acoustics is an area of this hobby that I'm really still clueless on.


----------



## erwinfrombelgium

If your room is untreated, there is a big chance that you have big nulls and/or big peaks at one or more frequencies, no matter if your system goes to 10 Hz or not. That's the whole point of bass traps, to smooth out those dips and peaks. DRC cannot cure nulls. More traps = more (useful) bass

I am sure more knowledgeable folks will chime in.


----------



## Mfusick

erwinfrombelgium said:


> If your room is untreated, there is a big chance that you have big nulls and/or big peaks at one or more frequencies, no matter if your system goes to 10 Hz or not. That's the whole point of bass traps, to smooth out those dips and peaks. DRC cannot cure nulls. More traps = more (useful) bass
> 
> I am sure more knowledgeable folks will chime in.


This is true.

You generally don't have problems at 10hz either.

It's worse than that, cause you have them in the more audible midbass regions where you can clearly tell difference because it's audible.


----------



## HopefulFred

AllenA07 said:


> ...I've got dual SVS subs (corner loaded) and have usable bass to just north of 12hz. I don't really want to lose my ability to play that low by taming room modes.


That's fine. As the others said, there will be no measureable change in that regard.


AllenA07 said:


> On the subject of bass traps, my initial plans would not have floor to ceiling bass traps. Right now I'm looking with some interest at the GIK room kit 3, which would give me 4 traps, one for each corner plus make some headway on those first reflection points. Are traps still worth it if I'm not going to have floor to ceiling.


Yep. The more traps the better, so some is better than none.



AllenA07 said:


> Finally with bass traps, how much do they help control peaks and nulls? I assume the end game here is a flatter response, I just am not sure what I should be expecting.


Controling peaks and nulls is all they do - how much is reasonable question. The answer, as always, is "It depends." I wouldn't expect to take more than 3-5dB off of most peaks with a basic assortment of passive standard absorbers. Nulls should come up by a similar amount. Good before and after data on this is hard to find, but it is out there.



AllenA07 said:


> In terms of treating the room, my only other concern is using my bipole side surrounds. Those speakers depend on reflections to work, so wouldn't treating the room render them pointless?


If those speakers require reflections (which I find a little dubious, but I'm not well-informed) then you should figure out where those reflections happen and endeavor not to place absorption there. Other than that, have a good time.


And finally - if you are trying to smooth the bass response, the first move should be locating the subs themselves (As well as considering changing the seating positions). Corner loading tends to result in the highest peak output, but least smooth response. Having two subs (in different corners, obviously) should help to smooth some of the variation corner loading produces, but it can't smooth all of it. Opposing wall midpoints might give you a smoother response and less seat-to-seat variation, which would render DSP more effective.


----------



## Brian Fineberg

question...if im building corber bass traps with roxul...but cant go floor to ceiling due to a sub in that corner or other obstruction.. ...will that still be better than no trapping at all?


----------



## BllDo

Brian Fineberg said:


> question...if im building corber bass traps with roxul...but cant go floor to ceiling due to a sub in that corner or other obstruction.. ...will that still be better than no trapping at all?


It's going to depend on how much area you are able to cover. There's going to be a point where it's probably not really worth the effort. I'm not sure what that is, but I'd say between three and four feet would maybe be a minimum. Less than three feet, I'm not sure if it would do a whole lot.


----------



## dnoonie

Brian Fineberg said:


> question...if im building corber bass traps with roxul...but cant go floor to ceiling due to a sub in that corner or other obstruction.. ...will that still be better than no trapping at all?


Probably yes, cover as much of the corner as you still can. How much coverage can you do? Have you built panels before?

Here's some other thoughts. I have 2'x4'x4" floor set bass traps for the 4 corners of my room. I wanted to treat the side wall but couldn't because the bass trap was in the way so I simply angled the bass trap to have it cover more of the back wall so I'm now able to hang a diffuser on the side wall. I also have 12"x12"x18"x24" triangle traps that I use where the larger ones won't fit due to wall hung speakers, doorways and headroom limitations.
Good luck.

Cheers,


----------



## Brian Fineberg

dnoonie said:


> Probably yes, cover as much of the corner as you still can. How much coverage can you do? Have you built panels before?
> 
> Here's some other thoughts. I have 2'x4'x4" floor set bass traps for the 4 corners of my room. I wanted to treat the side wall but couldn't because the bass trap was in the way so I simply angled the bass trap to have it cover more of the back wall so I'm now able to hang a diffuser on the side wall. I also have 12"x12"x18"x24" triangle traps that I use where the larger ones won't fit due to wall hung speakers, doorways and headroom limitations.
> Good luck.
> 
> Cheers,


Yes I've built panels. My entire Ht is treated with wall panels etc. now looking to make bass traps. But in the front behind the screen the speakers I stands are in the way. In the back the left corner has a sub in it. And the other corner is free but near a walkway (would obstruct the walkway)

So back corner with the sub would be about 5' of bass trap above the speaker. That's really the only option


----------



## dnoonie

Brian Fineberg said:


> Yes I've built panels. My entire Ht is treated with wall panels etc. now looking to make bass traps. But in the front behind the screen the speakers I stands are in the way. In the back the left corner has a sub in it. And the other corner is free but near a walkway (would obstruct the walkway)
> 
> So back corner with the sub would be about 5' of bass trap above the speaker. That's really the only option


Yes, the 5' of treatment will make a difference.

The side that you can't treat the vertical corner on because it's a walkway...Can you treat the horizontal corners with bass traps in that location? If so that would help.

Cheers,


----------



## WereWolf84

Hi all acoustic treatment experts, need your advise & help!

Today I have free time to take REW measurement of my dual subs with UMIK-1 post Audyssey XT32, FYI subs placement and seating positions very limited and I'm sitting 1-2 feet from rear wall, there are 3 huge dips/nulls around 55Hz, 70Hz and 85Hz, any ideas what's the culprit and how to eliminate those huge dips/nulls? is it because of reflections (rear wall/floor?) and can be solved by building few very thick bass absorbers/traps? or adding few more subs will smooth the nulls?


----------



## raynist

Would 1 mil plastic be considered acoustically transparent? I am putting up 5.5 inches of ultratouch behind my screen. Was going to buy fabric to cover everything, but it will not be seen. The plastic is very cheap at Home Depot. Thought I could use this instead. 

Thanks
Ray


----------



## batlin27

I took a measurement of my theater last night. This is of my treated theater without the back wall treated (Sides, Front + corner bass traps in front)

Can someone please tell me what I am looking at? / Give an analysis

It looks like my SPL is pretty good (1/3 smoothing) 
It also looks like I have big problems under 45hz and a null at 100Hz, is this correct?

Room is approx 17' long by 12' wide
Measurements are from main listening position 6 ft from back wall and 6 foot from side wall


----------



## HopefulFred

WereWolf84 said:


> Hi all acoustic treatment experts, need your advise & help!
> 
> Today I have free time to take REW measurement of my dual subs with UMIK-1 post Audyssey XT32, FYI subs placement and seating positions very limited and I'm sitting 1-2 feet from rear wall, there are 3 huge dips/nulls around 55Hz, 70Hz and 85Hz, any ideas what's the culprit and how to eliminate those huge dips/nulls? is it because of reflections (rear wall/floor?) and can be solved by building few very thick bass absorbers/traps? or adding few more subs will smooth the nulls?


Can you hear those nulls? They look like cancellations due to reflections, and they may be narrow enough that you don't hear them.

Nulls are always some kind of cancellation, and that can - in theory - be resolved with absorption. All of the above is a potential solution, but you need more data to know up front. You also need to decide what you're looking for at other seating positions. XT32 measures at multiple seats, doesn't it?


----------



## HopefulFred

raynist said:


> Would 1 mil plastic be considered acoustically transparent? I am putting up 5.5 inches of ultratouch behind my screen. Was going to buy fabric to cover everything, but it will not be seen. The plastic is very cheap at Home Depot. Thought I could use this instead.
> 
> Thanks
> Ray


If you are installing 5.5" of absorption purely for the bass absorption capability, then thin plastic is adequately transparent. However, behind a screen there is often a comb filtering of sorts that happens with high frequency reflection between the rear surface of the screen and the wall - 1mil plastic may not be adequately transparent to address this concern.


----------



## HopefulFred

batlin27 said:


> I took a measurement of my theater last night. This is of my treated theater without the back wall treated (Sides, Front + corner bass traps in front)
> 
> Can someone please tell me what I am looking at? / Give an analysis
> 
> It looks like my SPL is pretty good (1/3 smoothing)
> It also looks like I have big problems under 45hz and a null at 100Hz, is this correct?
> 
> Room is approx 17' long by 12' wide
> Measurements are from main listening position 6 ft from back wall and 6 foot from side wall


The dip at 100Hz doesn't show up with 1/3 octave smoothing, so I would forget it. There's a good chance it is related to a standing wave between the floor and ceiling and will be tough to treat anyway. The ringing below 45Hz is unclear, since we don't see it tail off in your plot. If you can extend the time in the diagram, you may find that this is just your room's noise floor.


----------



## raynist

HopefulFred said:


> If you are installing 5.5" of absorption purely for the bass absorption capability, then thin plastic is adequately transparent. However, behind a screen there is often a comb filtering of sorts that happens with high frequency reflection between the rear surface of the screen and the wall - 1mil plastic may not be adequately transparent to address this concern.


Thanks. 

I ended up using 0.31 mil plastic. 

As a non scientific test I covered one of my headphone (just left side) with this and could not hear a difference. 

I have some 2.5 inch acoustic foam I was thinking on putting on the front of the traps behind the screen to help wih high frequencies.


----------



## HopefulFred

raynist said:


> As a non scientific test I covered one of my headphone (just left side) with this and could not hear a difference.


It could also be that, probably like me, you don't hear much above about 15KHz.


----------



## WereWolf84

HopefulFred said:


> Can you hear those nulls? They look like cancellations due to reflections, and they may be narrow enough that you don't hear them.
> 
> Nulls are always some kind of cancellation, and that can - in theory - be resolved with absorption. All of the above is a potential solution, but you need more data to know up front. You also need to decide what you're looking for at other seating positions. XT32 measures at multiple seats, doesn't it?


Thanks for your opinion, FYI that Audyssey XT32 calibration was done at one middle seat only (my couch have 4 seats), I also suspect those 3 huge nulls due to cancellation which caused by reflections especially rear wall since I sit so close to rear wall.

what additional data to know? speaker & subs placement? dual subs placed right below my screen, with center speaker placed in between dual subs, LR on both sides of subs


----------



## raynist

HopefulFred said:


> It could also be that, probably like me, you don't hear much above about 15KHz.


This is true, I can't hear 16khz tone at all.


----------



## HopefulFred

WereWolf84 said:


> what additional data to know? speaker & subs placement? dual subs placed right below my screen, with center speaker placed in between dual subs, LR on both sides of subs


What are the room dimensions - a diagram is often easiest/best.


----------



## WereWolf84

HopefulFred said:


> What are the room dimensions - a diagram is often easiest/best.


The living room is 14.5ft x 16.5ft x 8ft with windows, door and open area to kitchen


----------



## HopefulFred

Okay, it doesn't look like those nulls are related to modal resonances. Instead, IMO, they look like single reflections from three separate nearby surfaces - spaced 60 inches away for the lowest frequency null, then 48 inches and 40 inches for each of the next two.

I'm still inclined to question whether or not they are actually audible.










If they are a nuisance, moving the listening position would be my first recommendation and absorption after that.


----------



## myfipie

> I'm still inclined to question whether or not they are actually audible.


The Q looks pretty narrow so I would tend to agree.


----------



## WereWolf84

HopefulFred said:


> I'm still inclined to question whether or not they are actually audible.





myfipie said:


> The Q looks pretty narrow so I would tend to agree.


 in other words, which means I can ignore these nulls? please correct me if I'm wrong

I feel lack of those chest thumping mid bass


----------



## HopefulFred

Right. If you can't hear them, ignore them.

I'm not very confident in saying this, but I think you're looking at the wrong band if you're chasing chest thumping. That tends to be a little higher. If you have the system headroom, try some eq in the 120-150Hz neighborhood.


----------



## FriscoDTM

I built several 703 panels and super chunk style bass traps, and I'm ready to finish them off and am wondering if I should cover them with something before applying the fabric. I see some commercial products that include a layer to reflect some of the high frequencies - which materials are recommended to mimic this type of effect? Would something simple like a layer of brown craft paper or pink floor protection paper do it or do they use much more advanced materials to get the acoustic effects?


----------



## batlin27

HopefulFred said:


> The dip at 100Hz doesn't show up with 1/3 octave smoothing, so I would forget it. There's a good chance it is related to a standing wave between the floor and ceiling and will be tough to treat anyway. The ringing below 45Hz is unclear, since we don't see it tail off in your plot. If you can extend the time in the diagram, you may find that this is just your room's noise floor.


Thank you!


----------



## pittsoccer33

Given how massive this thread has become, can anyone point me to a quick start guide to properly assessing acoustic treatment needs? I could start sticking that Corning stuff or foam all over my basement, but I really don't know what would actually help me.


----------



## WereWolf84

pittsoccer33 said:


> Given how massive this thread has become, can anyone point me to a quick start guide to properly assessing acoustic treatment needs? I could start sticking that Corning stuff or foam all over my basement, but I really don't know what would actually help me.


start with REW measurement for your room


----------



## myfipie

FriscoDTM said:


> I built several 703 panels and super chunk style bass traps, and I'm ready to finish them off and am wondering if I should cover them with something before applying the fabric. I see some commercial products that include a layer to reflect some of the high frequencies - which materials are recommended to mimic this type of effect? Would something simple like a layer of brown craft paper or pink floor protection paper do it or do they use much more advanced materials to get the acoustic effects?


Yes using something like craft paper will work. Keep in mind though you do not want panels with a membrane (the craft paper) in the any of the early reflection points.
http://www.gikacoustics.com/video-early-first-reflection-points/


----------



## myfipie

pittsoccer33 said:


> Given how massive this thread has become, can anyone point me to a quick start guide to properly assessing acoustic treatment needs? I could start sticking that Corning stuff or foam all over my basement, but I really don't know what would actually help me.


All small rooms need lot of bass trapping in corners, so that is a given. Testing is great way to see the progress but also great for making sure you have the speakers set up right also. Here is a video on using REW.
http://www.gikacoustics.com/room-eq-wizard-tutorial/


----------



## raynist

I am making some panels and traps out of ultratouch denim insulation (5.5 inch thick). I am covering most of my front wall with it. I have my LCR (JTR 212HTR's) and two of my 4 PSA Triax's behind the screen. The right most Triax is 18 inches from the right corner and the leftmost is another 18 inches to the left. The speakers are on homemade stands about 16 inches tall and hollow underneath. The layout is like this (JTR-Triax-JTR-Triax-JTR). Can I put some traps in the bottom right corner (under the right JTR 212) even though it is only 18 inches from the Triax? Would it be beneficial to fill the area between the Triax's and under each stand with ultratouch? How far should I keep each trap from one of the Triax woofers?

Thanks
Ray


----------



## cyclonus714

raynist said:


> I am making some panels and traps out of ultratouch denim insulation (5.5 inch thick). I am covering most of my front wall with it. I have my LCR (JTR 212HTR's) and two of my 4 PSA Triax's behind the screen. The right most Triax is 18 inches from the right corner and the leftmost is another 18 inches to the left. The speakers are on homemade stands about 16 inches tall and hollow underneath. The layout is like this (JTR-Triax-JTR-Triax-JTR). Can I put some traps in the bottom right corner (under the right JTR 212) even though it is only 18 inches from the Triax? Would it be beneficial to fill the area between the Triax's and under each stand with ultratouch? How far should I keep each trap from one of the Triax woofers?
> 
> Thanks
> Ray


Some theaters on this forum (for example, Cinemar), have done 1" treatments all around the room. In other cases, I've heard from some folks, like GIK, that it's better to do at least 3/4" for proper absorption of bass frequencies even at first reflection points or none at all. Otherwise, you're just absorbing high frequencies. Is this just personal preference or is there actual a best practice on this?


----------



## asarose247

Looking to add 6 2' x 4' 703 panels to my front wall.
The pics are of a corner mockup 
What I want to do is take advantage of using the edges of the 703 panels for any extra sound that just might be bouncing around . . .
So the frame is outside dimension, 2' x 4'. and about 2"+ or 2 1/2 deep, and have 2 center braces at about 16" and 32" for stability/rigidity, and the roundover on the corner is 1/2"
I want to use that "standoff" from the wall as an absorption "enhancement", as I have read here can be of some benefit by not having the panel flat to the wall
so the 703 panel will rest on the 3/4 edge of the ply but I will also have an AT backing very sheer material panel stapled on first, for support and fiber controll
I have "modded" a plastic 3 way drywall corner piece and attached as shown, will give me a 1 7/8's depth at the four corners.
Then the whole thing gets painted , as needed, and wrapped in my finish AT fabric.
Because I have not so flat plaster walls, I will run a weatherproofing foam strip, 1/2" x 1/4" (thick) on the back 3/4 ply frame edge.
Then when it is set onto the wall using a french cleat, it will (HA! HA!) seal onto the wall, if ever so slightly and also provide some vibration damping against the LF in the roof.

all in all not so different from how most approach this as part of the solution, "What about the Room?"

feedback welcomed


----------



## dnoonie

asarose247 said:


> Looking to add 6 2' x 4' 703 panels to my front wall.
> The pics are of a corner mockup
> What I want to do is take advantage of using the edges of the 703 panels for any extra sound that just might be bouncing around . . .
> So the frame is outside dimension, 2' x 4'. and about 2"+ or 2 1/2 deep, and have 2 center braces at about 16" and 32" for stability/rigidity, and the roundover on the corner is 1/2"
> I want to use that "standoff" from the wall as an absorption "enhancement", as I have read here can be of some benefit by not having the panel flat to the wall
> so the 703 panel will rest on the 3/4 edge of the ply but I will also have an AT backing very sheer material panel stapled on first, for support and fiber controll
> I have "modded" a plastic 3 way drywall corner piece and attached as shown, will give me a 1 7/8's depth at the four corners.
> Then the whole thing gets painted , as needed, and wrapped in my finish AT fabric.
> Because I have not so flat plaster walls, I will run a weatherproofing foam strip, 1/2" x 1/4" (thick) on the back 3/4 ply frame edge.
> Then when it is set onto the wall using a french cleat, it will (HA! HA!) seal onto the wall, if ever so slightly and also provide some vibration damping against the LF in the roof.
> 
> all in all not so different from how most approach this as part of the solution, "What about the Room?"
> 
> feedback welcomed


For a spacer I simply hang on a 3/4" plywood strip. It cuts the number of holes in the wall by 50% over z-clips alone. Pic 7992 attached. I mounted z-clips to a 5'8" by 3" strip of 3/4 ply then attach to the wall with screws to studs then hung 3 2'x4' absorbers on it. The spacing from the wall with z-clips attached 7/8". You could use a thicker mounting strip if you wanted more space.

For your corner, I used 1/8" plywood squares from, http://www.craftparts.com/geometric-shapes-rectangles-square-cutout-c-209_213_252_253.html. The attached picture is of a corner with a 3"x3" square, I ended up using 3 1/4" x 4 1/2", pic 8287. I held the corners with a corner clamp,









I glued the 1/8 ply to the frame, held them square with the clamp and used the 16awg nail gun to secure things together while the glue dried.

Most of my panels are closed back. It makes things easier, I wanted open back for these frames since they simply hold corner treatments in place and cover them without actually containing the material, gravity is my friend in this case.

Hope these ideas are helpful, use what works. Another thought if you want side absorption is to slot the side, although for all the panels I'm using I don't think it makes a lot of difference.


----------



## dnoonie

Oh. And from the bottom spacer I simply use 1" foam core squares held together with double sided tape and stuck to the back of the absorber with double sticky foam tape. See pic below.


----------



## asarose247

^ 
Thanks for some good ideas, , hanging wiht the z-clips, I have a few sets and especially the use of the 1/8" material as a corner 'gusset" stabilizer.

I have that same corner /miter clamp set up . . very handy , especially for this hobby.

TY


----------



## dnoonie

The corner stabilizer.

I got a small order from Craftparts just to try the 1/8 " hobby squares as a brace. I did a destructive test with just 16awg nails and a panel would likely come apart if someone leaned against it with all their full weight but not with the glue. Those silly little things are pretty solid once the butt joint corner and hobby square brace are glued. I rounded my corners with 80 grit on an orbital sander, it worked fine but sometimes I wish I had a router. I was gluing and nailing 5 panels an hour by the time I finished the last of my 19x24ID panels. I'd rather buy but this was too much of a custom thing to expect someone else to do it the way it needed done. Especially since I didn't know how it needed done till it was done.

Cheers,


----------



## pletwals

cyclonus714 said:


> Some theaters on this forum (for example, Cinemar), have done 1" treatments all around the room. In other cases, I've heard from some folks, like GIK, that it's better to do at least 3/4" for proper absorption of bass frequencies even at first reflection points or none at all. Otherwise, you're just absorbing high frequencies. Is this just personal preference or is there actual a best practice on this?


1" thickness is little more than a tweeter filter. You want the whole frequency spectrum absorbed. You need at least 3" for that. More is better. And you can lower the lowest frequency absorbed by spacing the panel away from the wall/ceiling the same distance (AKA plenum) as the panel thickness.

You can also improve the low frequency absorption by choosing heavier fiber glass / rockwool. I used a quality suited for flat roof insulation... 5" thick with extra 3" plenum. Works superbly.


----------



## cyclonus714

pletwals said:


> 1" thickness is little more than a tweeter filter. You want the whole frequency spectrum absorbed. You need at least 3" for that. More is better. And you can lower the lowest frequency absorbed by spacing the panel away from the wall/ceiling the same distance (AKA plenum) as the panel thickness.
> 
> You can also improve the low frequency absorption by choosing heavier fiber glass / rockwool. I used a quality suited for flat roof insulation... 5" thick with extra 3" plenum. Works superbly.


Is this case even with significant bass trapping elsewhere (corners, soffit, riser, etc)?


----------



## myfipie

cyclonus714 said:


> Is this case even with significant bass trapping elsewhere (corners, soffit, riser, etc)?


For the most part yes. If not you end up only "eqing" the reflection vs absorbing it all. Don't get me wrong, I have plenty of customers that only use 2" on the side walls, with bass trapping in corners, but I always recommend 4" whenever possible.


----------



## asarose247

@ pletwals 
Quote:
You can also improve the low frequency absorption by choosing heavier fiber glass / rockwool. I used a quality suited for flat roof insulation... 5" thick with extra 3" plenum. Works superbly.

Could you provide more info about which fiberglass and a picture or 2, especially the "plenum" construct?

Thanks


----------



## erwinfrombelgium

asarose247 said:


> @ pletwals
> Quote:
> You can also improve the low frequency absorption by choosing heavier fiber glass / rockwool. I used a quality suited for flat roof insulation... 5" thick with extra 3" plenum. Works superbly.
> 
> Could you provide more info about which fiberglass and a picture or 2, especially the "plenum" construct?
> 
> Thanks


It was Rockwool, not fiber glass Rhinnox

You can realize a plenum by simply hanging it from cables, whatever keeps it in the air...


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## Oledurt

*Very happy*

I have a new home, and a dedicated theater in my basement. 2 walls are concrete the other two drywall, and concrete floor covered with thick pad and carpet. For a year I have had no acoustic treatment other than a large couch and some drapes covering an archway into the room.

As you can imagine there was a good amount of slap echo, and flutter. Recently I added 6 gik tri traps. This cleaned up the bass of my two rythmik subs immensely. Real noticable difference. This led me to by some 2 inch and 4 inch foam from ATS Acoustics. I know some people hate the foam, but it was within my budget and constraints of my room.

I placed the 4 inch foam on the rear wall as i sit closer than 10 feet to it. I placed the other foam at the first reflection points of my speakers including my atmos on ceiling speakers. I also placed foam on the ceiling at the reflection points of my front three speakers. Finally, I placed foam directly to the sides, and above the seats.

I reran audyssey xt32, and the results are nothing less than stunning! Midrange is so much clearer, and acurate. Pans front to rear are astonishing. The atmos trailers omg very good. 

I watched gravity in atmos. I like this because the voices move all over the room with great accuracy. In my untreated room the "atmos effect" was just mediocre. In the treated room it was literally jaw dropping, and I mean outstanding! 

You know I am excited, but let me say this was the best $1000 I have spent on this hobby. Anyone on the fence about room treatments just do it! Trust me it will take your experience to a whole new level! Do the research, it is completely within your reach. 

Now off to watch another movie! 😁


----------



## johnnymacIII

Oledurt said:


> I have a new home, and a dedicated theater in my basement. 2 walls are concrete the other two drywall, and concrete floor covered with thick pad and carpet. For a year I have had no acoustic treatment other than a large couch and some drapes covering an archway into the room.
> 
> As you can imagine there was a good amount of slap echo, and flutter. Recently I added 6 gik tri traps. This cleaned up the bass of my two rythmik subs immensely. Real noticable difference. This led me to by some 2 inch and 4 inch foam from ATS Acoustics. I know some people hate the foam, but it was within my budget and constraints of my room.
> 
> I placed the 4 inch foam on the rear wall as i sit closer than 10 feet to it. I placed the other foam at the first reflection points of my speakers including my atmos on ceiling speakers. I also placed foam on the ceiling at the reflection points of my front three speakers. Finally, I placed foam directly to the sides, and above the seats.
> 
> I reran audyssey xt32, and the results are nothing less than stunning! Midrange is so much clearer, and acurate. Pans front to rear are astonishing. The atmos trailers omg very good.
> 
> I watched gravity in atmos. I like this because the voices move all over the room with great accuracy. In my untreated room the "atmos effect" was just mediocre. In the treated room it was literally jaw dropping, and I mean outstanding!
> 
> You know I am excited, but let me say this was the best $1000 I have spent on this hobby. Anyone on the fence about room treatments just do it! Trust me it will take your experience to a whole new level! Do the research, it is completely within your reach.
> 
> Now off to watch another movie! 😁


Awesome! I plan to treat my room this spring. What rythmik subs do you have?


----------



## AllenA07

I had a quick question that I wanted to run by this group. I'm getting ready to buy acoustic treatments for my room and the last sticking point I have is on bass traps. I'm planning on using GIK at this point and I'm looking at adding tri-traps to all the corners. Due to budget constraints, I will initially be adding a single tri-trap to each corner, and then in the future look into adding another one on top. Having only half the corner treated is my point of concern, is it something that will still yield improvements, or are corner bass traps one of those all or nothing deals.

As a side note, I've been thrilled working with GIK. I've been working with Bryan Pape over there and am very impressed at how much help they have offered me in terms of getting my speakers into the correct positions before I start spending money on acoustic treatments. For somebody who really feels lost in the world of acoustics, I've been very happy with GIK.

First set of treatments looks like it is going to be corner traps (depending on the feedback here), point of first reflection on the side walls, some bass trapping at the reflection point on the ceiling, and then 2 monster traps to play around with. Depending on results, I'm thinking I might put them on the front wall over the tri-traps, or on the back wall of the room.


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## dholmes54

Well what about the idea of using concrete forms 12 in diameter about 4 ft tall filled with insulation paint them and stick them in the corners as bass traps,maybe drill a few holes in the tubes for the bass could pass through,bad or good idea?Its sounds cheap for me being poor!


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## erwinfrombelgium

Why concrete?
12" seems inadequate. 24" sounds better...


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## BllDo

He is talking about a concrete form like Sonotube. That would look like something like the classic ASC Tube Trap, but the real thing is much more complex. In reality, even drilling holes in it wouldn't be worth the effort. You may be able to get just the right number of holes or just the right pattern to tune to a frequency that would impact the sound in your room, but it would probably end up not doing much. 

Bass traps don't have to be expensive though. Mineral wool insulation makes a good acoustic absorber and is pretty cheap. If you like the round shape of the tube trap, you can just make a form like this one and fill it it mineral wool. The thicker you can make it, the better it will be. You can even use mineral wool to make absorbers to hang on your wall. They may have to be a little thicker than your standard 2" rigid fiberglass absorbers, but they do work pretty well.


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## dholmes54

Thxs guys!


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## myfipie

AllenA07 said:


> I had a quick question that I wanted to run by this group. I'm getting ready to buy acoustic treatments for my room and the last sticking point I have is on bass traps. I'm planning on using GIK at this point and I'm looking at adding tri-traps to all the corners. Due to budget constraints, I will initially be adding a single tri-trap to each corner, and then in the future look into adding another one on top. Having only half the corner treated is my point of concern, is it something that will still yield improvements, or are corner bass traps one of those all or nothing deals.
> 
> As a side note, I've been thrilled working with GIK. I've been working with Bryan Pape over there and am very impressed at how much help they have offered me in terms of getting my speakers into the correct positions before I start spending money on acoustic treatments. For somebody who really feels lost in the world of acoustics, I've been very happy with GIK.
> 
> First set of treatments looks like it is going to be corner traps (depending on the feedback here), point of first reflection on the side walls, some bass trapping at the reflection point on the ceiling, and then 2 monster traps to play around with. Depending on results, I'm thinking I might put them on the front wall over the tri-traps, or on the back wall of the room.


Great that Bryan has been helpful!  Covering floor to ceiling in all corners is always recommended, but plenty of customers start with one in each corner and go from there. You have to start somewhere and 4 will help! 

Use the Monsters on the back wall for sure!


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## AllenA07

I've been messing around in this hobby for the last 15 years, and this weekend managed to learn something. I've always been very dubious of the "snake-oil" that acoustic panels are. I've always assumed that because I have a AVR with Audyssey treatments aren't that necessary. After spending a lot of time reading through this thread, I finally decided I would make an investment and try treating my room, though admittedly I spent the entire time thinking I should just spend the extra money and get an AVR with Audyssey XT32 instead.

Can't believe how wrong I was on everything above. I got my GIK panels installed on Friday afternoon and had the theater back up and running by Friday night. I ended up going with bass traps in all 4 corners (only half up the wall, a future upgrade will take care of that problem) as well as treating the point of first reflections on both the walls and ceiling. Finally I put some additional traps along the back wall. After getting everything adjusted and running Audyssey the results were really stunning. Everything sounds better, the bass is more refined, dialog is cleaner, even my bipole side surrounds sound better. I ran some charts with REW, and found that from basically 63hz down to 15hz I'm +/- 3db. While there are still a few problems above 63hz, my nulls have become smaller portions of the frequency response, and have become far more shallow. I've watched two movies in there since adding the panels, plus run my bass scene demos (Game of the Thrones, Battle of the Blackwater, and Iron Man 3 battle scene) and everything just sounds dramatically improved.

I was a bit surprised at the impact of Audyssey in the room. I had always viewed it as being a replacement for acoustically treating the room. I think it has actually done more this time then any previous time I've run it. All things considered, this was a huge upgrade to my theater all around. Huge thanks to the guys over at GIK for all the help adjusting my speaker placement, and working with me on figuring out what I actually needed in the room. It took two weeks and about 60 emails and a few phone calls to get there, but dollar for dollar this ranks as one of the best upgrades I've done.


----------



## HT-Eman

Retrofitted my acoustic panels with HTD in-ceiling speakers for Dolby Atmos. Room is far from finished but this is how it looks as of now. This is a Top Middle speaker setup.


----------



## myfipie

> Huge thanks to the guys over at GIK for all the help adjusting my speaker placement,


You are very welcome sir and thanks for the support. At the last trade show we did out in CA, we actually treated a room, played a song and then pulled the treatment out and replayed the same song. It truly was a eye opener for the people there. I guess it is just something you have to experience to understand.


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## amit916

Doing research for a new theater build (exciting, but also frightening proposal...) and after doing enough research on all the components, I have turned to the room build and have just now dove head first into acoustic treatment. Unfortunately it doesn't jive, at all, for the aesthetic I wanted to create inside the room.

I wanted to go with a simple black theme with red carpets and wanted to hang light boxes inside the theater; however glass/acrylic sheets reflect sound very well.

Is there any way for me to have my cake and eat it too? (as in treat the room acoustically that might mitigate having the posters?)


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## artur9

amit916 said:


> Is there any way for me to have my cake and eat it too? (as in treat the room acoustically that might mitigate having the posters?)


There's a thread for making posters out of acoustic treatments. http://www.avsforum.com/forum/19-de...inted-movie-poster-acoustic-panels-cheap.html


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## amit916

artur9 said:


> There's a thread for making posters out of acoustic treatments. http://www.avsforum.com/forum/19-de...inted-movie-poster-acoustic-panels-cheap.html


I saw that, but I was hoping to hang light boxes... prefer those aesthetically.


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## BllDo

amit916 said:


> I wanted to go with a simple black theme with red carpets and wanted to hang light boxes inside the theater; however glass/acrylic sheets reflect sound very well.


They also reflect light very well and would be horribly distracting while watching a movie. Really a terrible idea.


----------



## RapalloAV

I recently installed a whole wall (floor to ceiling) behind all my front speakers with rockwool, in behind my AT screen. Most of its 8" thick and some areas for bass trapping 16" thick.
Since then the imaging has been phenomenal, plus I hear so much more I never ever heard in movies I have re run... Im also hearing tiny background noises the mic is picking up that was never there in the past and probably never intended the audience would even hear in a cinema.... Its a good thing and sometimes a bad thing having all the detail so in your face now! What is this phenomena of the front wall rockwool that actually enhances the detail in the sound this way, since most situations unless they are dedicated rooms could ever achieve this??? The detail, imaging and bass have improved enormously, its a great and exciting to hear now.....The other thing I notice with DSU is sound coming from where there are NO speakers in the room!!! Often my eyes jump to say where wides would be as sound bounces out from that position from time to time (a car door, birds, whatever) but I have no speakers there... This also happens from "other" locations in the room.... I do run an 11.1 setup but speakers arnt covering all the walls.... An interesting phenomena since the rockwall was added to the front wall in such density...


----------



## erwinfrombelgium

I presume the fact is that the front wall is the nearest surface, hence it benefits most from treatment. Especially if it's very broadband! 8" is great.


----------



## empirebuilder

Questions for the acoustic treatment experts here. 
I am nearing completion on my acoustical installation. Right now I have the "Linacoustic sandwich" (1" LA 4mil poly 1" LA) on the front wall, 4" OC703 on the back wall with 6 mil poly covering.


Question 1: My side walls are 2" OC703 full wall for first 7 feet then up to 5' height for the remainder of the walls next to the seating. For the area above 5' is that just left bare drywall covered with the GOM? Old way was poly batting behind this. Is diffusion needed? I notice the professionals use scrim but I'm not sure on correct placement.


Question 2: I had planned to treat underneath my soffits with 1" Linacoustic wrapped in GOM. The "old way" also mentioned treating under soffits to deal with tricorners. With current thought, should I still treat the undersides of my soffits or just leave them bare wood wrapped in GOM.


Thanks!!


http://www.avsforum.com/forum/19-de...71225-leisure-rules-theater-construction.html


----------



## asoofi1

RapalloAV said:


> I recently installed a whole wall (floor to ceiling) behind all my front speakers with rockwool, in behind my AT screen. Most of its 8" thick and some areas for bass trapping 16" thick.
> Since then the imaging has been phenomenal, plus I hear so much more I never ever heard in movies I have re run... Im also hearing tiny background noises the mic is picking up that was never there in the past and probably never intended the audience would even hear in a cinema.... Its a good thing and sometimes a bad thing having all the detail so in your face now! What is this phenomena of the front wall rockwool that actually enhances the detail in the sound this way, since most situations unless they are dedicated rooms could ever achieve this??? The detail, imaging and bass have improved enormously, its a great and exciting to hear now.....The other thing I notice with DSU is sound coming from where there are NO speakers in the room!!! Often my eyes jump to say where wides would be as sound bounces out from that position from time to time (a car door, birds, whatever) but I have no speakers there... This also happens from "other" locations in the room.... I do run an 11.1 setup but speakers arnt covering all the walls.... An interesting phenomena since the rockwall was added to the front wall in such density...


Do you have absorbers or diffusers anywhere else in the room, or just basically 'dead' up front as you described? And which part of wall did you put the 16" for trapping?

I'm debating between doing the same as you or doing the Linacoustic/Poly sandwich.


----------



## stef2

My first reflection points are all covered with two inches of OC703, spaced at 1 inch (air) from the walls.

What difference would there be if I filled that one inch of air with an additional layer of OC703? I guess it would absorb slightly deeper, but up to what extent? should I do it?


----------



## dnoonie

stef2 said:


> My first reflection points are all covered with two inches of OC703, spaced at 1 inch (air) from the walls.
> 
> What difference would there be if I filled that one inch of air with an additional layer of OC703? I guess it would absorb slightly deeper, but up to what extent? should I do it?


As myfipie said a few pages back...fiberglass absorbs more than air, or something like that. If you have the money and space thicker is better, leaving an air gap, plenum as was stated a few pages back, is an inexpensive additional advantage. I started out using a gap so I could run cables, I discovered first hand that it made a significant difference and started hanging on a mounting strip/spacer with the rest of my panels. The mounting strip also has the advantage of being more secure since I mount the strip into studs and also means fewer holes in the wall compared to using z-clips alone.

Hope this helps...

Cheers,


----------



## Al Sherwood

RapalloAV said:


> I recently installed a whole wall (floor to ceiling) behind all my front speakers with rockwool, in behind my AT screen. Most of its 8" thick and some areas for bass trapping 16" thick.
> Since then the imaging has been phenomenal, plus I hear so much more I never ever heard in movies I have re run... Im also hearing tiny background noises the mic is picking up that was never there in the past and probably never intended the audience would even hear in a cinema.... Its a good thing and sometimes a bad thing having all the detail so in your face now! What is this phenomena of the front wall rockwool that actually enhances the detail in the sound this way, since most situations unless they are dedicated rooms could ever achieve this??? The detail, imaging and bass have improved enormously, its a great and exciting to hear now.....The other thing I notice with DSU is sound coming from where there are NO speakers in the room!!! Often my eyes jump to say where wides would be as sound bounces out from that position from time to time (a car door, birds, whatever) but I have no speakers there... This also happens from "other" locations in the room.... I do run an 11.1 setup but speakers arnt covering all the walls.... An interesting phenomena since the rockwall was added to the front wall in such density...


Any chance we could get a few pictures? 

Also I see that you are in New Zealand, what material did you use?


----------



## myfipie

dnoonie said:


> As myfipie said a few pages back...fiberglass absorbs more than air, or something like that. If you have the money and space thicker is better, leaving an air gap, plenum as was stated a few pages back, is an inexpensive additional advantage. I started out using a gap so I could run cables, I discovered first hand that it made a significant difference and started hanging on a mounting strip/spacer with the rest of my panels. The mounting strip also has the advantage of being more secure since I mount the strip into studs and also means fewer holes in the wall compared to using z-clips alone.
> 
> Hope this helps...
> 
> Cheers,


Yes but in his case I would make them 4" with the gap if possible.


----------



## RapalloAV

Al Sherwood said:


> Any chance we could get a few pictures?
> 
> Also I see that you are in New Zealand, what material did you use?



Sorry too late, I would have to unhook all my AT screen and remove the masking to remove the screen to take pictures...
Just do a Goggle on Rockwool its available everywhere.


----------



## Al Sherwood

RapalloAV said:


> Sorry too late, I would have to unhook all my AT screen and remove the masking to remove the screen to take pictures...
> Just do a Goggle on Rockwool its available everywhere.


No worries, I thought if it were a specific product then I would look for it's equivalent here.

I suspect that is much like this: http://www.roxul.com/products/residential/products/roxul+safe'n'sound

I will be re-installing my AT screen and may be trying to do the same thing behind the screen.


----------



## stef2

dnoonie said:


> As myfipie said a few pages back...fiberglass absorbs more than air, or something like that. If you have the money and space thicker is better, leaving an air gap, plenum as was stated a few pages back, is an inexpensive additional advantage. I started out using a gap so I could run cables, I discovered first hand that it made a significant difference and started hanging on a mounting strip/spacer with the rest of my panels. The mounting strip also has the advantage of being more secure since I mount the strip into studs and also means fewer holes in the wall compared to using z-clips alone.
> 
> Hope this helps...
> 
> Cheers,


My question was: I already have an air gap. Should I fill it?...


----------



## RapalloAV

Al Sherwood said:


> No worries, I thought if it were a specific product then I would look for it's equivalent here.
> 
> I suspect that is much like this: http://www.roxul.com/products/residential/products/roxul+safe'n'sound
> 
> I will be re-installing my AT screen and may be trying to do the same thing behind the screen.


 This is the stuff you need, this site is Canada. http://www.rockwool-searox.com/prod...stic-insulation/searox-sl-340-(marine-slab-80)
You need the most dense rigid one 4" thick.


----------



## empirebuilder

Any thoughts about treating undersides of soffits? I think I have my diffusion question answered..


----------



## HopefulFred

empirebuilder said:


> Any thoughts about treating undersides of soffits?


 I think it has been competently recommended to apply treatments there, with the presumption, I believe, that the absorption is broad band.

My perspective is that if it's not useful for bass trapping, I wouldn't do it. I might be alone there.


----------



## dnoonie

empirebuilder said:


> Any thoughts about treating undersides of soffits? I think I have my diffusion question answered..


Do you mean behind/inside the soffit, ie. between the soffit and the wall and not visible, or outside the soffit and below and visible?

I've filled the hidden space behind/inside the soffit with foam triangle bass absorbers since my room had an even response and the foam also had an even absorption, fiberglass or rockwool would work better if you had bass peaks or nulls that needed tamed. Horizontal bass trapping certainly makes a difference. My philosophy for sound treatment is treat what you know you should, test and work froward from there.

Hope this helps.

Cheers,


----------



## empirebuilder

Thanks for the replies. I am talking about adding 1" of Linacoustic to the bottom of the soffits. I'd have 1/2" plywood covered by LA and GOM attached to the bottoms of my soffits.

You can see photos of the soffits at the bottom of my thread page http://www.avsforum.com/forum/19-de...71225-leisure-rules-theater-construction.html

I know this was recommended in years past on the forum by some experts and wanted to make sure this was still the case. I mounted my lights into separate panels so I could add treated panels to the undersides everywhere else.


Inside the soffit I stuffed with pink fluffy.


----------



## Al Sherwood

RapalloAV said:


> This is the stuff you need, this site is Canada. http://www.rockwool-searox.com/prod...stic-insulation/searox-sl-340-(marine-slab-80)
> You need the most dense rigid one 4" thick.


Thanks for the link, but I don't think that the material is readily available in Canada, although interestingly enough the distributor (about 4000km away) is the same company that makes the Roxul I am looking at. I wonder how close the two materials are in performance and overall effect. The Roxul product is available at the local building supply store and is made from what most people call 'rock wool'.

http://www.roxul.com/files/RX-NA_EN...ets/Residential/US Accordian Brochure Eng.pdf


----------



## asoofi1

Trying to figure out the benefits of two front wall treatments...I just saw a pic of a commercial Atmos theater under construction and was told it was 2" cotton covering the entire concrete wall...which me wonder about going with linacoustic.

What are the pros/cons for each?
-2" 3lb Cotton semi-rigid boards 
-1" Linacoustic/4ml Poly/1" Linacoustic sandwich

Any other front wall options I should consider?


----------



## asoofi1

Trying to figure out the benefits of two front wall treatments...I just saw a pic of a commercial Atmos theater under construction and was told it was 2" cotton covering the entire concrete wall...which me wonder about going with linacoustic.

What are the pros/cons for each?
-2" 3lb Cotton semi-rigid boards 
-1" Linacoustic/4ml Poly/1" Linacoustic sandwich

Any other front wall options I should consider?


----------



## dnoonie

empirebuilder said:


> Thanks for the replies. I am talking about adding 1" of Linacoustic to the bottom of the soffits. I'd have 1/2" plywood covered by LA and GOM attached to the bottoms of my soffits.
> 
> You can see photos of the soffits at the bottom of my thread page http://www.avsforum.com/forum/19-de...71225-leisure-rules-theater-construction.html
> 
> I know this was recommended in years past on the forum by some experts and wanted to make sure this was still the case. I mounted my lights into separate panels so I could add treated panels to the undersides everywhere else.
> 
> 
> Inside the soffit I stuffed with pink fluffy.





asoofi1 said:


> Trying to figure out the benefits of two front wall treatments...I just saw a pic of a commercial Atmos theater under construction and was told it was 2" cotton covering the entire concrete wall...which me wonder about going with linacoustic.
> 
> What are the pros/cons for each?
> -2" 3lb Cotton semi-rigid boards
> -1" Linacoustic/4ml Poly/1" Linacoustic sandwich
> 
> Any other front wall options I should consider?


Okay, since no one else has looked it up I did. It appears the Linacoustic material is a specificity material for duct work, pretty much the same as 703, rock wool, or... If the poly coating is on the outside it would tend to reflect higher frequencies and pass/absorb lower frequencies, if on the inside it would tend to act as a barrier reflecting sound back through the material for absorption. 1" really isn't enough absorption, 2" minimum. 

If it were up to me I'd use the 2" 3lb cotton semi-rigid board, hey that's exactly what I did actually except it was 4lb, http://www.acoustimac.com/ecoinsul422/, I used this in addition to the triangle foam were vertical corners meet horizontal corners for added absorption. Use the cotton or the material from acoustimac.com (looks like it's made from industrial clothing manufacture cutting waste and is much nicer to work with than fiberglass or rock wool, no need to mask up or use special clothing). And if you want barrier material or diffusion get it separately, if you have the space get separate barrier or diffusion if that's what you're looking for. I'd use 4" or 6" in corners and the back wall.

empirebuilder
I'd leave your soffit open so sound could pass into the cavity and be absorbed by the insulation you have inside, it would also be nice to have the inside of the soffit somehow accessible for running/modifying wiring. Consider covering absorption with acoustic fabric as a covering for your soffits, it could be framed, or not, it could be hinged for access or you could leave one end accessible and put in conduit for running cable. Keep in mind that you might want added audio channels in the middle so leaving the entire space somehow accessible might be better than a front to back conduit run...just some thoughts to consider. I covered open frames with acoustic fabric and hinged each in sections for my soffit, here's another idea from another member, http://www.avsforum.com/forum/19-de...eadwood-theater-comes-alive.html#post17170107.

Cheers,


----------



## mrevo2u

Over the years i have read much of this thread trying to keep up with the current school of thought regarding acoustic treatment. It has changed quite a bit and it would be a HUGE help if some of the industry reps here can summarize current acoustic treatment trends.

I see some people doing 2"front wall treatmenr, some linacoustic sandwich, others 6" or 8" broadband on front wall........


----------



## Noman74656

mrevo2u said:


> Over the years i have read much of this thread trying to keep up with the current school of thought regarding acoustic treatment. It has changed quite a bit and it would be a HUGE help if some of the industry reps here can summarize current acoustic treatment trends.
> 
> 
> 
> I see some people doing 2"front wall treatmenr, some linacoustic sandwich, others 6" or 8" broadband on front wall........



Anthony Grimani (of MSR Acoustics) has been on a couple of the Home Theater Geeks podcast episodes where he goes into how he believes room treatments should be set up. I have found them very informative and helpful.


Sent from my iPhone using Tapatalk


----------



## Brian Fineberg

question...

I have 2 24"x24" treatments I bought from GIK that I want to repurpose for the ceiling (wrapping in black velvet)...

do I want to put them in front of my screen? on the ceiling? is there a rule of thumb for celing treatments and where they go? here is a shot of my screen wall.


----------



## BasementBob

dnoonie said:


> It appears the Linacoustic material is a specificity material for duct work, pretty much the same as 703, rock wool, or... If the poly coating is on the outside it would tend to reflect higher frequencies and pass/absorb lower frequencies, if on the inside it would tend to act as a barrier reflecting sound back through the material for absorption.


Linacoustic's coating does not behave that way at high frequencies.
Please see http://www.bobgolds.com/AbsorptionCoefficients.htm 

Linacoustic's coating is there to keep the fibers in and the dust out, which makes it ideal for HVAC duct lining.
If you can't cover front wall absorption with GoM or something, then Linacoustic's coating would instantly be tempting.


----------



## empirebuilder

dnoonie said:


> empirebuilder
> I'd leave your soffit open so sound could pass into the cavity and be absorbed by the insulation you have inside, it would also be nice to have the inside of the soffit somehow accessible for running/modifying wiring. Consider covering absorption with acoustic fabric as a covering for your soffits,


Thanks Dnoonie. Early on I looked into keeping the soffit acoustically open for bass trapping. In my case I ran HVAC through the soffit so I have to enclose it so sound doesn't run into the flex duct and escape the room.
I am thinking of using hanger bolts to keep these panels in place, which allows me to remove the panels if/when needed. 
Whatever I use on the bottom of the soffits, I'll cover with GOM Onyx which I've used on my front wall.


----------



## johnnymacIII

Brian Fineberg said:


> question...
> 
> I have 2 24"x24" treatments I bought from GIK that I want to repurpose for the ceiling (wrapping in black velvet)...
> 
> do I want to put them in front of my screen? on the ceiling? is there a rule of thumb for celing treatments and where they go? here is a shot of my screen wall.


That depends on what first reflections you want to treat. have someone get on a ladder with a mirror and move across the ceiling and you sit in your main seat. When you see the speaker whose first reflection you want to treat in the mirror, mark it with tape and install the treatment there.


----------



## cholmes1

I am looking to purchase some audio treatment panels but am curious if the adage 'you get what you pay for' applies in this world?

GIK has some nice options (built in diffuser, etc.) and a new line of patents, but the pricing seems high for a wood frame and insulation. Is there something more to them?

For a contrast Acoustimac and Atsacoustics seem to sell very similar products but at slightly lower price points. 

DIY is not an option, so I guess ultimately which acoustic treatment company has the most bang for buck?

Thank you for any assistance.


----------



## dnoonie

cholmes1 said:


> I am looking to purchase some audio treatment panels but am curious if the adage 'you get what you pay for' applies in this world?
> 
> GIK has some nice options (built in diffuser, etc.) and a new line of patents, but the pricing seems high for a wood frame and insulation. Is there something more to them?
> 
> For a contrast Acoustimac and Atsacoustics seem to sell very similar products but at slightly lower price points.
> 
> DIY is not an option, so I guess ultimately which acoustic treatment company has the most bang for buck?
> 
> Thank you for any assistance.


The GIK have a built in plenum. There may be differences in shipping/boxing/packaging that are represented in product cost rather than shipping plus product cost so look at cost shipped. Room kits can save money too.
Cheers,


----------



## cholmes1

Thank you for the insight. I was unaware that GIK were the only builder to include a plenum. I assume this increases the absorption range?


----------



## myfipie

johnnymacIII said:


> That depends on what first reflections you want to treat. have someone get on a ladder with a mirror and move across the ceiling and you sit in your main seat. When you see the speaker whose first reflection you want to treat in the mirror, mark it with tape and install the treatment there.


Agreed.. YOu can use the following video to give you a hand at finding the early reflection points.
http://www.gikacoustics.com/video-early-first-reflection-points/


----------



## myfipie

johnnymacIII said:


> That depends on what first reflections you want to treat. have someone get on a ladder with a mirror and move across the ceiling and you sit in your main seat. When you see the speaker whose first reflection you want to treat in the mirror, mark it with tape and install the treatment there.


Agreed.. YOu can use the following video to give you a hand at finding the early reflection points.
http://www.gikacoustics.com/video-early-first-reflection-points/


----------



## myfipie

cholmes1 said:


> I am looking to purchase some audio treatment panels but am curious if the adage 'you get what you pay for' applies in this world?
> 
> GIK has some nice options (built in diffuser, etc.) and a new line of patents, but the pricing seems high for a wood frame and insulation. Is there something more to them?
> 
> For a contrast Acoustimac and Atsacoustics seem to sell very similar products but at slightly lower price points.
> 
> DIY is not an option, so I guess ultimately which acoustic treatment company has the most bang for buck?
> 
> Thank you for any assistance.


I own GIK so................................ But no our panels are not just normal framed up panels. We have a patent on the 242, 244 and Monster that absorb more due to the way they are built. If you notice the 242 is actually 3.5" thick which is not a normal 2" panel that you see on websites. Sure we might be couple dollars more but we feel the extra quality and absorption is worth it. See more here.
http://www.gikacoustics.com/why-choose-gik-bass-trap-acoustic-panel-diffusor/
Ok enough sales pitch..

We are not the only people out in the market so buy from the person you feel most comfortable with. If you need help with your room we are there to help you if you need it. 
http://www.gikacoustics.com/acoustic-advice/


----------



## cholmes1

myfipie said:


> I own GIK so................................ But no our panels are not just normal framed up panels. We have a patent on the 242, 244 and Monster that absorb more due to the way they are built. If you notice the 242 is actually 3.5" thick which is not a normal 2" panel that you see on websites. Sure we might be couple dollars more but we feel the extra quality and absorption is worth it. See more here.
> http://www.gikacoustics.com/why-choose-gik-bass-trap-acoustic-panel-diffusor/
> Ok enough sales pitch..
> 
> We are not the only people out in the market so buy from the person you feel most comfortable with. If you need help with your room we are there to help you if you need it.
> http://www.gikacoustics.com/acoustic-advice/


Hello Glenn,

I appreciate your response and can certainly understand your bias towards your own product. I actually just completed an acoustic advice session with Bryan at GIK and he was extremely helpful. I will be looking to follow his advice in the coming weeks.

Best,
Charles


----------



## jh901

I plan to use 1" thick pipe insulation for bass trapping and early reflection absorption. I'll use 16" diameter cylinders in the corners and I'd planned to conceal them using a floor to ceiling fabric covered frame which fits diagonally. Does the fabric need to be Guilford (or other relatively transparent fabric) in order to effect the bass properly? I was hoping to use black velvet in order to eliminate screen reflection. I'd presume to use Guilford to wrap the 9" cylinders placed at the side reflection points since the higher frequencies need to penetrate into the insulation.


----------



## bambam

Dennis Erskine said:


> Quote:
> 
> Do not place a subwoofer such that the driver is aimed into the seating locations (in a residential sized room). If you do, you should place a 1" thick piece of 1.5 PCF fiberglass in front of the driver. Sometimes it requires 2".
> Quote:wavelength bigger than will fit into the room
> 
> .


Why is this? Reasons? If the subs are currently aimed at the listening position, should you move them slightly so they aim along the side wall?


----------



## Dennis Erskine

The only reason you can localize a subwoofer is due to the higher frequency artifacts the sub produces when making sound. These include air slap against the cone and other noises created by the motor. Those are pretty directional. Aiming away from the ears or the 1" of fiberglass will solve that and not cause any adverse performance issues with the subwoofer.


----------



## ps24eva

What material would you use to make a 10 foot long acoustic panel?


----------



## 8681962

I'm in the finalizing stages of my HT and I'm wondering if I should already implement bass trapping treatments before actually finishing up and measuring everything. My original plans include "superchunk" type bass traps in the corners along the front wall, right next to the screen.

Is it beneficial to build them now or can it have a negative impact? By reading most of the comments here it seems the general consensus is "more is better" with bass traps.

The room is 12' 11⅞" x 10' 7½" with a height of 7' 6⅝" and I have dual SVS PB-1000's.


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## Irv Kelman

Run your subs MONO and place them in the midline of your theater. One in font of the screen and one on the back wall.


----------



## myfipie

duboisph said:


> I'm in the finalizing stages of my HT and I'm wondering if I should already implement bass trapping treatments before actually finishing up and measuring everything. My original plans include "superchunk" type bass traps in the corners along the front wall, right next to the screen.
> 
> Is it beneficial to build them now or can it have a negative impact? By reading most of the comments here it seems the general consensus is "more is better" with bass traps.
> 
> The room is 12' 11⅞" x 10' 7½" with a height of 7' 6⅝" and I have dual SVS PB-1000's.
> 
> View attachment 1038065
> View attachment 1038073


You can always test before hand but in the end you will need bass trapping in as many corners as possible, so do it now or later. Testing is great though to see the progress and also make sure you have the speaker/seating spots in the ideal locations in the room.


----------



## dnoonie

ps24eva said:


> What material would you use to make a 10 foot long acoustic panel?


It's not really possible to answer without more information. I could do some guessing, then you could clarify.

A 10 foot "panel" is quit large so I guess that you may actually mean built in, it could be framed out with just about any dimensional lumber to the thickness of your desired low end cutoff, then filled with fiberglass, rock wool or recycled fibers and covered with acoustic fabric.

If you mean removable 10 foot panel I'd suggest that you reconsider unless there's a compelling reason for it like a continuous printed image you want to stretch across the panel, even so I'd suggest making it in sections and covering them without the print, then hang the separate sections, connect the sections, and stretch the acoustic fabric print over that.

Cheers,


----------



## 8681962

Irv Kelman said:


> Run your subs MONO and place them in the midline of your theater. One in font of the screen and one on the back wall.


For practical reasons I won't be able to do that: center speaker in the front, AV cabinet in the back. But I have other placement options: both in the front at 1/3ths, anywhere along the side walls, in a corner on the front and on the back, ... Once the room is finished and everything is connected I'll have to experiment.



myfipie said:


> You can always test before hand but in the end you will need bass trapping in as many corners as possible, so do it now or later. Testing is great though to see the progress and also make sure you have the speaker/seating spots in the ideal locations in the room.


Thanks Glenn. Acoustic treatments is all new to me. I understand that bass trapping will be required in any case, but I'm afraid of doing it "wrong". Filling the corners with triangle fiberglass wedges with some fabric in front seems pretty easy to DIY. Won't a trap like this absorp too much in the higher frequencies too? Any important things I need to consider? 

Anyway, with or without the corner traps, the amount of fabric I will need to finish the screen wall will be the same, so time to order some nice Camira fabric via GIK then .


----------



## myfipie

> Thanks Glenn. Acoustic treatments is all new to me. I understand that bass trapping will be required in any case, but I'm afraid of doing it "wrong". Filling the corners with triangle fiberglass wedges with some fabric in front seems pretty easy to DIY. Won't a trap like this absorp too much in the higher frequencies too? Any important things I need to consider?


If you are concerned about over absorbing the upper frequencies you could just FRK on the fronts. On our products we use either our Range Limiter or our Scatter Plate just for that reason. Our limiter is much more aggressive than FRK, but the FRK can work.


----------



## 8681962

myfipie said:


> If you are concerned about over absorbing the upper frequencies you could just FRK on the fronts. On our products we use either our Range Limiter or our Scatter Plate just for that reason. Our limiter is much more aggressive than FRK, but the FRK can work.


Allright. Guess I'll just bite the bullet then, Thanks for the input


----------



## Irv Kelman

duboisph said:


> For practical reasons I won't be able to do that: center speaker in the front, AV cabinet in the back. But I have other placement options: both in the front at 1/3ths, anywhere along the side walls, in a corner on the front and on the back, ... Once the room is finished and everything is connected I'll have to experiment.D.





Check out this Power Point on sub placement: http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/multsubs.pdf


----------



## ps24eva

Can someone dumb down when to use linacoustic vs rockboard?


----------



## JonasHansen

Hi all!

I could use some input on my upcoming theater room. The room is about 16.5 feet long and 10 feet wide so it is not the biggest room seen on AVSForum, but I wanna optimize the result.

I will build a baffle wall for the speakers which are JBL SK2-1000. These speakers have very smooth off-axis response and the baffle wall will be covered with absorbtion.

To help me with the acoustics, I wrote some software where I can enter the dimensions, place the speakers/seats and then it does a visualization of all reflections for each speaker in each seat. I am not focusing on bass treatments yet.










I could use some input on my approach, which is the following:

Good reflections:
- Right wall reflections from right speaker
- Left wall reflections from left speaker

Bad reflections:
- Right wall reflections from left speaker
- Left wall reflections from right speaker
- All SBIR-related issues.

I would treat the good reflections with some kind of BAD-panel like treatment which absorbs and at the same time reflects and adds some diffusion (Yellow). The bad reflections would be absorbed with absorbers (Orange).
Back wall would be some kind of diffusors (Blue).

Exact seating position and speaker position is still not determined, but the overall approach would be the same if seating is moved a little.

Would love to hear your input!


----------



## sdurani

JonasHansen said:


> Exact seating position and speaker position is still not determined, but the overall approach would be the same if seating is moved a little.
> 
> Would love to hear your input!


Similar to what I like, with a couple small differences based on my personal preference: would put absorption instead of diffusion at the middle of the back wall and would add absorption forward of the BAD panels to reduce later reflections.


----------



## JonasHansen

sdurani said:


> Similar to what I like, with a couple small differences based on my personal preference: would put absorption instead of diffusion at the middle of the back wall and would add absorption forward of the BAD panels to reduce later reflections.


When you say "forward of the BAD pabels", what exactly do you mean? To replace them with absorbtion?


----------



## sdurani

JonasHansen said:


> When you say "forward of the BAD pabels", what exactly do you mean?


The untreated section of side wall between the BAD panels and the front wall.


----------



## jaykay0222

I have read this thread for days and trying gain some basic knowledge on treating my room. I have had my media room for about 2 years and it is in the 2nd floor. No basements in here where we live (that sucks)

I plan to take care of first reflections, wall behind LR, wall behind the seating area and corner bass traps. I used the mirror trick for the 1st reflection panels

Here are my questions
1. My center channel is right below my screen; how do I treat that area
2. what is the best method for treating my ceiling. Plan is to cover the cloud area over the seating 
3. My surround speakers are bipole; how do you treat those
4. Plan to use foam based bass traps covering all 4 corners (top and bottom) - Is it any good

I'm not going DIY route; rather ordering from ATS

Please let me know your inputs


----------



## JonasHansen

sdurani said:


> The untreated section of side wall between the BAD panels and the front wall.


Ahh yes, that makes perfect sense. Maybe I should extend the software to be able to show 2nd and 3rd order reflections.

Thanks for your input!


----------



## Irv Kelman

jaykay0222 said:


> I have read this thread for days and trying gain some basic knowledge on treating my room. I have had my media room for about 2 years and it is in the 2nd floor. No basements in here where we live (that sucks)
> 
> I plan to take care of first reflections, wall behind LR, wall behind the seating area and corner bass traps. I used the mirror trick for the 1st reflection panels
> 
> Here are my questions
> 1. My center channel is right below my screen; how do I treat that area
> 2. what is the best method for treating my ceiling. Plan is to cover the cloud area over the seating
> 3. My surround speakers are bipole; how do you treat those
> 4. Plan to use foam based bass traps covering all 4 corners (top and bottom) - Is it any good
> 
> I'm not going DIY route; rather ordering from ATS
> 
> Please let me know your inputs


Move the seating away from the back wall for better bass reproduction.


----------



## jaykay0222

Irv Kelman said:


> Move the seating away from the back wall for better bass reproduction.


I would be able to move by couple of feet; anything more would be too close to my screen


----------



## sdurani

JonasHansen said:


> Ahh yes, that makes perfect sense.


Only if you share my tastes in room tuning. Try it and decide for yourself.


> Maybe I should extend the software to be able to show 2nd and 3rd order reflections.


If you want, but it's not that necessary since we already know that those reflections will be forward of the 1st reflection points.


----------



## JonasHansen

sdurani said:


> Only if you share my tastes in room tuning. Try it and decide for yourself. If you want, but it's not that necessary since we already know that those reflections will be forward of the 1st reflection points.


My experience tells me that I definately prefer the room on the dead/dry side. So eliminating the later reflections would likely be my preference as well.

In my current room I switched from absorbtion to diffusion on the back wall, and I think that improved the sound. The room is still on the dead side though.


----------



## Irv Kelman

jaykay0222 said:


> I would be able to move by couple of feet; anything more would be too close to my screen


A few feet can make all the difference.


----------



## dnoonie

*Addition of diffusion and switching from absorbers to diffusion.*

Room size about 11.5 feet by 16.5 feet by 8 foot room
10 2 foot by 4 foot QRD 7 6 inch diffusors
Note that aside from the diffusion behind the front main speakers that all diffusion is backed with absorption. 
Also note that the 2 2" absorbers from the side back wall will go on the ceiling to cover front speaker first and second reflection points for the second row of seats I will be adding.

*Rear channel side first and second reflection points:*
Removed and replaced 2 2" absorbers with 2 QRD 7 diffusors, diffusors are spaced 1 1/2 inches from the wall and back filled with fabric waste/paper waste rigid board.
Relocated 2 4" bass absorbers 1 foot forward for 2 diffusors, mounted mirror image with zero spacing to panels above and also backed with absorption.

*Rear corners/back wall:*
Placed 2 QRD 7 diffusors on back wall 3/5 covering L/R rear corner bass absorbers

*Front wall:*
Placed 2 QRD 7 diffusors behind main L/R speakers

*Front Side/Front corner:
*Placed 2 QRD 7 diffusors on front/side wall 3/4 covering front corner bass absorbers

*Initial observations:*
The the room still sounds isolated and quiet.
When you move around you notice your own foot steps are louder and your clothing rubbing on itself is louder

*Initial music listening observations 2 channel, MLP is 7 feet from speakers:*
The sound stage is the same width as before adding diffusion 
The sound stage is deeper by about 25%, 2 channel tracks that feature significant fx to create a 3d sound stage are much deeper, sounds that were once a couple feet in front of me are now in my face, sounds that were once beside and slightly in front of me are now slightly behind me. A shift of about 2 feet or so.

Although the room measures about the same flatness frequency wise the sound is more lively and less damped sounding.

Emotional impact: Initial 2 channel listening was breathtakingly wonderful, one of the best listening experiences I've had. It was likely exaggerated by the fact that it's been 4 months and I've only listened to one other decent sound system.

All in all I'm very pleased.

*5.1 observations:
*I can run the surround channels as hot (as measured with test tones) as the front channels without rear channel localization/spottiness
Although rear channels are much more present they call less attention to themselves.
Note that there has been more scrutiny (critical *thinking*, because being critical without thinking is just an insult) given to 2 channel listening than to 5.1 listening. I'll have to reevaluate after watching some of my surround demo favorites.

*Things I tried*
I tried placing diffusion at front first and second reflection points and it simply smeared the imaging, diffusion at that position is too close to the MLP. Additionally it took up too much space in my relatively small room, behind and beside the front speakers seems to be a better location. for that diffusion.

Cheers!

Don't' forget to have some fun every day!


----------



## Waheed001

Hi everyone I am looking at making my own cylinder bass traps using r6 rockwool slabs. I may also consider using the r6's for sound absorbers for the first reflection point (back wall) Anyone who has done diy can you please chime in and shed some light on the matter? open to suggestions

Thanks in advance


----------



## jaykay0222

jaykay0222 said:


> I have read this thread for days and trying gain some basic knowledge on treating my room. I have had my media room for about 2 years and it is in the 2nd floor. No basements in here where we live (that sucks)
> 
> I plan to take care of first reflections, wall behind LR, wall behind the seating area and corner bass traps. I used the mirror trick for the 1st reflection panels
> 
> Here are my questions
> 1. My center channel is right below my screen; how do I treat that area
> 2. what is the best method for treating my ceiling. Plan is to cover the cloud area over the seating
> 3. My surround speakers are bipole; how do you treat those
> 4. Plan to use foam based bass traps covering all 4 corners (top and bottom) - Is it any good
> 
> I'm not going DIY route; rather ordering from ATS
> 
> Please let me know your inputs


guys - appreciate inputs on this set up


----------



## luisev

jaykay0222 said:


> guys - appreciate inputs on this set up


ATS is great to work with. I purchased from from their Amazon store (had a bunch of gift cards) along with some extra material. I then picked up 2' x 4' x 4" corner traps from Acoustimac and recovered them with the ATS fabric so they all matched. I went with their corner traps instead of super chunk type traps as the room doubles as our living room. Wife wasn't keen on floor to ceiling corner traps, so I had to somewhat compromise. Due to their angled design, they tuck neatly into the corners. Behind my center and below my TV I have an ATS 1' x 4' x 2" panel. Hope that helps...


----------



## woolfman

Can anyone suggest an alternative to Johns Manville Insulshield Coated Black Roll? I am trying to locate this or anything else for my screen wall which I am failing to do. I cannot find anything around here in ohio. I appreciate any help!


----------



## luisev

Sorry for the double post, but I hit enter too quick. For the surrounds, ATS told me to use the same mirror trick to find the reflections for the surrounds; however, I didn't treat those reflections. Not sure about foam for bass traps as I've read that fiberglass or rockwool are the best stuffing material to use. I didn't consider ceiling treatment as my living room performs double duty, but call ATS and I'm sure they will give you some good suggestions.


----------



## johnnymacIII

jaykay0222 said:


> I have read this thread for days and trying gain some basic knowledge on treating my room. I have had my media room for about 2 years and it is in the 2nd floor. No basements in here where we live (that sucks)
> 
> I plan to take care of first reflections, wall behind LR, wall behind the seating area and corner bass traps. I used the mirror trick for the 1st reflection panels
> 
> Here are my questions
> 1. My center channel is right below my screen; how do I treat that area
> 2. what is the best method for treating my ceiling. Plan is to cover the cloud area over the seating
> 3. My surround speakers are bipole; how do you treat those
> 4. Plan to use foam based bass traps covering all 4 corners (top and bottom) - Is it any good
> 
> I'm not going DIY route; rather ordering from ATS
> 
> Please let me know your inputs


1. Use a long shag area rug. 

2. Use the mirror trick on the ceiling with 4 inch bass traps. 

3. Don't treat them.

4. Don't use foam, but Use 7 inch bass traps in corners and back wall.

Hope this helps. This is what I would do if going the DIY route.


----------



## Stoked21

Hoping someone here can help. In construction for back of AT screen acoustic treatment and may have messed up!!! Finishing it tomorrow and can still reverse course now if need be:

I've spent all day today demolishing my old theater front that was all carpentry with a 65" lcd tv in a basement. It's a 9'x16'x3' hwd cove in the room. Going to have an AT screen and need to deaden the front acoustically with treatment. 

Currently:
Concrete foundation--studs with pink insulation in cavity--standard 5/8" drywall. 

I just started putting up 1" (probably true 3/4") firing strips with adhesive and Brad nails, not green glue. Plan tomorrow is to install 5/8" 2'x4' certainteed theater black fiberglass acoustic tiles (nrc of about 75 and light reflectivity of about 3%) This stuff is very light weight, I can pickup a box of 16 with one hand easily. . Plan to put small dab of liquid nails on each corner and adhere it to the wood firring strips leaving ~1"air gap between them and drywall. Seams between panels not taped off or sealed but putting the panels snugly against each other. so these things can be lossy. 

Plan:
Concrete foundation--studs with pink insulation in cavity--standard 5/8" drywall--Fir strips with ~3/4"-1" air gap--5/8" fiberglass ct tiles loosely attached 

I'm now worried does that count as a triple leaf wall??? Is it MAMAM? Or is fiberglass tiles like this okay? Should I attach directly to drywall without wood strips?

Pics here:
http://www.avsforum.com/forum/19-de...69-stoked-home-theater-kc-3.html#post39120834


----------



## HopefulFred

I say you have not created a triple. You're good to go (though some might suggest you should be doubling the absorption).


----------



## Mashie Saldana

dnoonie said:


> *Addition of diffusion and switching from absorbers to diffusion.*
> 
> Room size about 11.5 feet by 16.5 feet by 8 foot room
> 10 2 foot by 4 foot QRD 7 6 inch diffusors
> Note that aside from the diffusion behind the front main speakers that all diffusion is backed with absorption.
> Also note that the 2 2" absorbers from the side back wall will go on the ceiling to cover front speaker first and second reflection points for the second row of seats I will be adding.
> 
> *Rear channel side first and second reflection points:*
> Removed and replaced 2 2" absorbers with 2 QRD 7 diffusors, diffusors are spaced 1 1/2 inches from the wall and back filled with fabric waste/paper waste rigid board.
> Relocated 2 4" bass absorbers 1 foot forward for 2 diffusors, mounted mirror image with zero spacing to panels above and also backed with absorption.
> 
> *Rear corners/back wall:*
> Placed 2 QRD 7 diffusors on back wall 3/5 covering L/R rear corner bass absorbers
> 
> *Front wall:*
> Placed 2 QRD 7 diffusors behind main L/R speakers
> 
> *Front Side/Front corner:
> *Placed 2 QRD 7 diffusors on front/side wall 3/4 covering front corner bass absorbers
> 
> *Initial observations:*
> The the room still sounds isolated and quiet.
> When you move around you notice your own foot steps are louder and your clothing rubbing on itself is louder
> 
> *Initial music listening observations 2 channel, MLP is 7 feet from speakers:*
> The sound stage is the same width as before adding diffusion
> The sound stage is deeper by about 25%, 2 channel tracks that feature significant fx to create a 3d sound stage are much deeper, sounds that were once a couple feet in front of me are now in my face, sounds that were once beside and slightly in front of me are now slightly behind me. A shift of about 2 feet or so.
> 
> Although the room measures about the same flatness frequency wise the sound is more lively and less damped sounding.
> 
> Emotional impact: Initial 2 channel listening was breathtakingly wonderful, one of the best listening experiences I've had. It was likely exaggerated by the fact that it's been 4 months and I've only listened to one other decent sound system.
> 
> All in all I'm very pleased.
> 
> *5.1 observations:
> *I can run the surround channels as hot (as measured with test tones) as the front channels without rear channel localization/spottiness
> Although rear channels are much more present they call less attention to themselves.
> Note that there has been more scrutiny (critical *thinking*, because being critical without thinking is just an insult) given to 2 channel listening than to 5.1 listening. I'll have to reevaluate after watching some of my surround demo favorites.
> 
> *Things I tried*
> I tried placing diffusion at front first and second reflection points and it simply smeared the imaging, diffusion at that position is too close to the MLP. Additionally it took up too much space in my relatively small room, behind and beside the front speakers seems to be a better location. for that diffusion.
> 
> Cheers!
> 
> Don't' forget to have some fun every day!


Nice, got any pictures?

I have a 12 x 12 x 8 foot room myself that will need treatment at some stage.


----------



## dnoonie

Mashie Saldana said:


> Nice, got any pictures?
> 
> I have a 12 x 12 x 8 foot room myself that will need treatment at some stage.


You bet. Eventually I'd like to create a build thread for my last upgrade, but...note that front diffusion will be covered in grey acoustically transparent cloth, maybe this week (these are factory seconds that were nearly destroyed during shipping and "repaired", they look hideous but they are quit functional), and that rear diffusion will be finished with MinWax Cherry stain, 2 to 4 coats, and a rub on Watco topcoat. (I really need to start that build thread but after, blah and blah and well lots of stuff). The finish test is on the left front repaired diffusior in the middle, that will be what the rear will look like by New Years I hope. 

Cheers,


----------



## Mashie Saldana

dnoonie said:


> You bet. Eventually I'd like to create a build thread for my last upgrade, but...note that front diffusion will be covered in grey acoustically transparent cloth, maybe this week (these are factory seconds that were nearly destroyed during shipping and "repaired", they look hideous but they are quit functional), and that rear diffusion will be finished with MinWax Cherry stain, 2 to 4 coats, and a rub on Watco topcoat. (I really need to start that build thread but after, blah and blah and well lots of stuff). The finish test is on the left front repaired diffusior in the middle, that will be what the rear will look like by New Years I hope.
> 
> Cheers,


That is a lot of treatment. What is the make/model of the diffusers?


----------



## dnoonie

Mashie Saldana said:


> That is a lot of treatment. What is the make/model of the diffusers?


They are ATS diffusors, the rear are the regular ones, http://www.atsacoustics.com/acoustic-diffusers.html, the front are clearance, http://www.atsacoustics.com/acoustic-diffuser-clearance.html. The clearance are a good buy just be aware that they are not something most folks would stain and finish. For all the trouble UPS caused with damage I think it would have been less of a problem to build them from scratch. Have them shipped by freight, it might cost more but the things I've had shipped freight arrive in perfect condition. If I were to do it again I'd consider the GIK gridfusor, http://www.gikacoustics.com/product/gik-acoustics-gridfusor/ instead of the ATS clearance and frame them, cover them and hang them. I think the regular ATS will look great once finished and at the time GIK didn't offer their QRD 7 unfinished and I wanted a specific color that tied in with the rest of the house and HT room.

I'm not sure what's available were you are in the UK but if you are handy with tools at all perhaps consider a knock down kit rather than pre-assembled, I think it may ship better, sadly the knock down kits I've found are the same price as assembled . Something else I've considered after the fact is to buy plans and have a local cabinet shop make them. Even if I would have to rent a truck to haul something made local across town it would be worth it compared to dealing with shipping damage.

I just looked at your theater thread. Are you planning a build? Here's a couple before pics and transition pics. Long story short, I had the wall and door added this summer to keep echos out of the HT room and painted very close to 18% neutral grey.

Cheers,


----------



## 357

Does anyone know if GIK is having a Black Friday or Cyber Monday sale?


----------



## chadamir

What are people's thoughts on using ultratouch for diy panels? I have some slabs of it that are 6-7 inches thick. I'm afraid though that the puffiness will make it look like I hung a pillow on the wall.


----------



## raynist

Let me prefrace this post with saying I have crappy DIY skills. 

I ordered 5 boxes of knauf 1.6lb ecose insulation panels from GIK to use behind my screen wall. I received them last week and have been thinking about how I can wrap them and build wooden panels for them. I want these to be 1ft thick. They come 6 per box and each panel is 2 inches thick. The box they come in is just a 1/4 inch shy of a foot thick so they shouldn't really be compressed in the box. 

I had an idea last night at about 3am when I woke up to get a drink. I thought about using the box to contain the fiberglass panels. I cut most of the box face out and figured I could glue some fabric over the exposed insulation. 

These will be behind a screen so looks are not an issue. I also thought about cutting the cardboard off the back too, but if I have these up against the wall I am not sure there would be any be benefit. I could probably cut more off of the opening but I am not sure if the box would lose too much rigidity. 

So do you think these 12 inch thick ghetto bass trap/panels would work?


----------



## HopefulFred

I'd probably take one out from the back and use it elsewhere. I like this idea^


----------



## dnoonie

raynist said:


> I ordered 5 boxes of knauf 1.6lb ecose insulation....
> 
> So do you think these 12 inch thick ghetto bass trap/panels would work?


They should work great as monster bass absorbers! I don't think you even need to be concerned with making a hole in the box if you don't want, the cardboard will reflect high frequencies but the setup will still make a great bass absorber without the cutout. I'm not exactly sure the peak absorption frequency for that particular setup but I'd guess you'd peak between 75Hz to 85Hz.

Cheers,


----------



## raynist

dnoonie said:


> They should work great as monster bass absorbers! I don't think you even need to be concerned with making a hole in the box if you don't want, the cardboard will reflect high frequencies but the setup will still make a great bass absorber without the cutout. I'm not exactly sure the peak absorption frequency for that particular setup but I'd guess you'd peak between 75Hz to 85Hz.
> 
> Cheers,


Here are all 5 completed ghetto bass traps. The middle one was my first attempt, need to fix up the material.


----------



## Skylinestar

dnoonie said:


> Here's a couple before pics and transition pics.


How's the DST-style corner bass traps? Are they effective?


----------



## Skylinestar

What's the maximum weight that can be supported by the metal-framed ceiling joist? How do I hang heavy ceiling absorbers and corner bass traps which require the ceiling to take the load? AFAIK, those metal bars are flimsy.


----------



## dnoonie

Skylinestar said:


> How's the DST-style corner bass traps? Are they effective?


Treating the horizontal corners with the foam corner traps made a measurable difference smoothing out nulls and peaks by about 4db to 6db, using one or two made no measurable difference, treating the entire horizontal area did. The difference was quit audible. If you look at the after pics you don't see them, that's because they're behind the panels. Although effective they were difficult to glue into place with a ceiling not square to the wall and waviness in both the ceiling and the wall, the glue is also a pain to clean up.

Here's more info:
http://www.avsforum.com/forum/19-de...reatments-master-thread-365.html#post36128410


Cheers,


----------



## myfipie

357 said:


> Does anyone know if GIK is having a Black Friday or Cyber Monday sale?


Hate to say but we have not raised our prices in over 5 years so we are not able to run any specials like that in 2015. We did how ever lowered the price of the Q7D by a ton so that should help out.


----------



## myfipie

raynist said:


> Let me prefrace this post with saying I have crappy DIY skills.
> 
> I ordered 5 boxes of knauf 1.6lb ecose insulation panels from GIK to use behind my screen wall. I received them last week and have been thinking about how I can wrap them and build wooden panels for them. I want these to be 1ft thick. They come 6 per box and each panel is 2 inches thick. The box they come in is just a 1/4 inch shy of a foot thick so they shouldn't really be compressed in the box.
> 
> I had an idea last night at about 3am when I woke up to get a drink. I thought about using the box to contain the fiberglass panels. I cut most of the box face out and figured I could glue some fabric over the exposed insulation.
> 
> These will be behind a screen so looks are not an issue. I also thought about cutting the cardboard off the back too, but if I have these up against the wall I am not sure there would be any be benefit. I could probably cut more off of the opening but I am not sure if the box would lose too much rigidity.
> 
> So do you think these 12 inch thick ghetto bass trap/panels would work?


What a GREAT IDEA!!


----------



## raynist

myfipie said:


> What a GREAT IDEA!!


Thanks Glenn 

I was pretty proud of myself for coming up with that at 3am 

I actually didn't even glue the fabric. I just cut it about 6 inches bigger than each side and tucked it in between the box and insulation. Each one cost about $65 total.


----------



## 357

myfipie said:


> Hate to say but we have not raised our prices in over 5 years so we are not able to run any specials like that in 2015. We did how ever lowered the price of the Q7D by a ton so that should help out.


Just placed an order and subscribed to newsletter. Let me know of any specials in 2016.


----------



## Skylinestar

I'm looking for some advise regarding cleaning up bass ringing in my living room. It's fully concrete built.
REW waterfall can be seen here

I know it's impossible for me to get bass decay within 450ms in my concrete room. 1650ms seems kinda excessive.
Currently, I have two 8' tall 8" thick basstraps on the left and right front wall-wall corners. I do have a feeling that it's still impossible to get the bass decay within 500ms with bass traps in all corners.
Please advise.


----------



## toofast68

Skylinestar said:


> I'm looking for some advise regarding cleaning up bass ringing in my living room. It's fully concrete built.
> REW waterfall can be seen here
> 
> I know it's impossible for me to get bass decay within 450ms in my concrete room. 1650ms seems kinda excessive.
> Currently, I have two 8' tall 8" thick basstraps on the left and right front wall-wall corners. I do have a feeling that it's still impossible to get the bass decay within 500ms with bass traps in all corners.
> Please advise.


More Traps....can you do a ceiling cloud (s), can you do rear traps somewhere ? Not much you can do super low of course....and I have some more tweaking...but traps work 

Here is my waterfall...your living room may limit you of course...but I've been down your rabbit hole and the only fix was LOTS O TRAPS!!


----------



## Skylinestar

toofast68 said:


> More Traps....can you do a ceiling cloud (s)


You mean 8" thick ceiling cloud?


----------



## toofast68

Well that certainly will help

Sent from my SM-G920V using Tapatalk


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## chadamir

Is there a way to tell just by looking that a rug will allow air to pass through it so I can put a pad underneath for more absorption? I know that if you try to blow through the back and can't it won't work for that purpose, but I cannot do that with rugs online.


----------



## myfipie

357 said:


> Just placed an order and subscribed to newsletter. Let me know of any specials in 2016.


Thanks for the order and for sure will let you know. We do have a few more things in the Alpha series that will be out VERY soon!


----------



## RamKat

This is more a request to the moderators/forum management than a post. To me the amp and speakers are the audio components to get the sound in the room. However, as many audiophiles have commented, once the sound is in the room, the diffuser panels, absorption panels and bass traps are just as important audio components as the speakers. Therefore, is it perhaps possible to add say three sub-forums (e.g. Diffuser panels, Absorption panels and Bass traps) in the audio section where these components can be discussed. I know there are general "construction" forums but the dedicated panel type topics get lost among the room construction discussions. Or am I missing something?


----------



## RamKat

Here is my Acoustical panel question. I have ordered some Rockboard 60 panels. Unfortunately it will only be delivered at the local distributor in the New Year. I am looking into the possibility to start making the frames over the Christmas break and I am now looking for the exact dimensions of these Rockboard 60 panels. I know they are 2 ft by 4 ft, but to make a frame were they could slide in I need to know if that translates to 48.00 by 24.00 inches, or are they slightly bigger or smaller? I am planning to cover them with with a thin acoustic transparent fabric before fitting them inside a painted frame. Any info will be appreciated.


----------



## AXLCMT

*Cottong Batting (is this too thin) How many layers of this should I use?* Did I buy the correct Cotton Batting for the side wall fabric panels 42" and up? I have 1" OC703 going from the floor up until ear level (42") and I am doing the usual Cotton Batting from 42" up to the ceiling. 



Below are photos of the Cotton Batting I purchased. It is two layers in the roll, so if my OC703 is 1" then I assume I need to use both layers of this Cotton Batting. 



Look how thin it is though. Each layer is about 1/8" to 1/4" in thickness. 



I could probably easily "quadruple" layer this Cotton Batting (4 layers) and still be under the 1" thickness mark. 



Any thoughts?


----------



## AXLCMT

So, what are people putting on their side walls these days from ear height to to the ceiling, if you are using OC703 Bass Trapping up to ear level from the floor?


----------



## johnnymacIII

Has anyone tried the Grimani technique of interweaving infusion and absorption? If so, how did it fare in your room? Also, could the same be achieved by just placing GIK acoustic absorption panels in the room with scatter plates added? Thanks.


----------



## Mashie Saldana

johnnymacIII said:


> Has anyone tried the Grimani technique of interweaving infusion and absorption? If so, how did it fare in your room? Also, could the same be achieved by just placing GIK acoustic absorption panels in the room with scatter plates added? Thanks.


That is the approach I will go for eventually (mixed diffusion and absorption), no idea what ratios you should aim for with the combi panels.


----------



## ippodrome

I was hoping on you guys to let me know if I can expect to build a room that sounds good with what I've got though it's quite small...
It's single plasterboard and uninsulated towards adjacent spaces and my daughters bedroom above.
I plan to take down the innerceiling and add acoustic hangers, complete decoupled inner ceiling system, double plasterboard with gg between the joists and add insulation. The walls will be staggered and double plasterboard with glue between. 
This part I'm fairly confident in how to tackle.... 
But what can I expect to be able accomplish in terms iof acoustic treatments, planning on building soffit treatments in at least sides- and back wall-ceiling corners. Panels on first reflectionpoints, but what else can I possibly fit in there.
Will have (front of) a recliner at about 2.5m (8 1/2') from screen (100" at) and maybe a extra small couch against back wall for the kids....
It will sound bad back there but I must have more than a loveseat since we have 4 kids who like to watch together sometimes...
Or maybe a couple of fatboy beanbags would be a better option. 
Room dimensions are W9' 8" L14' H8'

My speakers are 
LCR : Fusion8's (DiySG)
Surround and future atmos/Dts-x: Volt-6 (DiySG)
Subwoofer: 2 microcubes with Dayton RSS390ho powered by a t-amp 2400.

Hope not to have bored you with this post and to have some input!


----------



## Nightlord

ippodrome said:


> I was hoping on you guys to let me know if I can expect to build a room that sounds good with what I've got though it's quite small...
> It's single plasterboard and uninsulated towards adjacent spaces and my daughters bedroom above.
> I plan to take down the innerceiling and add acoustic hangers, complete decoupled inner ceiling system, double plasterboard with gg between the joists and add insulation. The walls will be staggered and double plasterboard with glue between.
> This part I'm fairly confident in how to tackle....
> But what can I expect to be able accomplish in terms iof acoustic treatments, planning on building soffit treatments in at least sides- and back wall-ceiling corners. Panels on first reflectionpoints, but what else can I possibly fit in there.
> Will have a recliner at about 2.8m (9' 12") from screen (100" at) and maybe a extra small couch against back wall for the kids....
> It will sound bad back there but I must have more than a loveseat since we have 4 kids who like to watch together sometimes...
> Or maybe a couple of fatboy beanbags would be a better option.
> Room dimensions are W9' 8" L14' H8'
> 
> My speakers are
> LCR : Fusion8's (DiySG)
> Surround and future atmos/Dts-x: Volt-6 (DiySG)
> Subwoofer: 2 microcubes with Dayton RSS390ho powered by a t-amp 2400.
> 
> Hope not to have bored you with this post and to have some input!


Check the room dimensions... I think you made a typo there, else your recliner would be embedded in the wall.


----------



## ippodrome

Yeah! Changed my seating distance a bit! Thanks for pointing that out...  @Nightlord do I remember correctly that Jens at Resonator designed your room? Or was that someone else? I'm situated in sthlm so it would be convenient to hire him...


----------



## Nightlord

ippodrome said:


> Yeah! Changed my seating distance a bit! Thanks for pointing that out...  @Nightlord do I remember correctly that Jens at Resonator designed your room? Or was that someone else? I'm situated in sthlm so it would be convenient to hire him...


No, the initial room design was made by Ingvar Öhman (Ino Audio). But he's just as convenient to hire up in Stockholm. ( And the more willing you are to build the acoustic treatments yourself, the more I would recommend him. ) 

( I have not had him re-design my room after I had to change dimensions slightly due to soundproofing towards the exterior, so it's most likely not as optimum with the design as it would have been on the original measurements, so I'm taking all blame on my own deviations. )


----------



## ippodrome

Ah, I see! 
Are you happy with how it sounds?
I wonder if there are any small rooms in STHLM that I can visit... 
I had a chat with Ingvar some months ago, I got the impression it would be easier to get him to design the room if I decided to use his speakers but maybe it's still possible and I misunderstood him...

I am definitely willing to build the treatments myself, that is if it's possible to get good results and it fits size wise.


----------



## Stoked21

So I'm preparing to treat my early reflection points by replacing posters with three panels (using mirror method). Also adding three bass traps to the back wall/door and corner traps in the back corner as well.

I spoke with an acoustic treatment company and they recommended nothing on the ceiling and no diffusors/scatter plates anywhere. My back wall is only about 3' from the MLP in the rear row. 

I guess I'm questioning if I really just need panels and traps everywhere with no diffusors. Does this seem like a sound approach? Any recommendations on how best to treat the room? Room is 7.2.4 heading to 9.2.6 very soon.
(The front wood working is gone in the room and it is now a treated area with a 130"wide AT screen.)


----------



## dnoonie

Stoked21 said:


> I spoke with an acoustic treatment company and they recommended* nothing on the ceiling and no diffusors/scatter plates anywhere*. My back wall is only about 3' from the MLP in the rear row.
> 
> I guess I'm questioning if I really just need panels and traps everywhere with *no diffusors*. Does this seem like a sound approach? Any recommendations on how best to treat the room? Room is 7.2.4 heading to 9.2.6 very soon.
> (The front wood working is gone in the room and it is now a treated area with a 130"wide AT screen.)


Their recommendation may be based on room size. What size is your room?

Nothing on the ceiling? I've found it very important to treat the ceiling. Do you have a drop down ceiling? If so the ceiling panels may be their own treatment. I did my ceiling as a step 2 process about a month after corners and first reflections. I wanted to experience/hear the difference before continuing.

I've been in rooms with scatter plates over absorption and (IMO) found that some distance is needed or imaging suffered 3 foot seemed to do it. Other folks experience/opinion is certainly different.

Cheers,


----------



## Stoked21

^^^^^

I call it 16'x17' plus about 3' behind the screen making it 19'x17'. The HT portion is only about 1/3 of the size. You can see there's no wall on the right side. It's the end part of a backwards 'L' shape in a basement. The pics showing the curtain are taken from the bottom corner of the L. The other portion is a bar/concession area. 

So the open area (no wall on the right side) looking into the HT is probably about 40' long actually. So the room is probably 19'x40' plus the bar if you count it all.


----------



## dnoonie

Hi Stoked21,

Scatter plates:
Corner bass traps could likely use the scatter plates.
First reflection points might work too, you could order your corner treatment first with scatter plates and place them at first reflection points to try it, then decide.
Second reflection points might work as well but are a less likely candidate then first reflection points, if you have enough corner treatments with scatter plates.
Back wall, I wouldn't use scatter plates but others might.

That large opening is going to be a big echo chamber. I just closed off my large opening to my HT room, it sure helps the MLP.

Cheers,


----------



## corradizo

If I have a 3D model of my room in sketchup, can I calculate the spots I would need diffusers or absorbers?


----------



## toofast68

Ceiling Cloud Question 

So I had a rather large issue with dialog, did some REW work and found a MASSIVE 1st ceiling reflection. So then I built a nice 4" thick cloud of rockwool - 6" off the ceiling to tame that and then to also absorb some bass.

My waterfall is really great, at 300 ms nearly everything but down (below 30hZ) is tamed.

HOWEVER, I now seem to have a slight issue with my Center Channel dipping in the 250 - 500 hZ range...










I can manually boost that range and the graph looks much better, so I am sure it is not a null (or at least I think I do)

Could my cloud be sucking the life out of that range perhaps ? I know it is not my speakers as I've tested them nearfield and outside and that dip is not there of course, so my room or my dang cloud.
If removing the cloud was easy, I could do that, but it is not, so before I do, I would love some thoughts. This hobby is nutty!
Below is with that range boosted on my AVR


----------



## Stoked21

Marked first reflection points with mirror trick. Back middle is MLP.
From left to right (green tape spots):

1. Front middle (Surround back right) and Back middle (surround right)
2. back middle (front right)
3. front middle (surround right)
4. back middle (center)
5. front middle (front right)
6. front middle (center)
7. back middle (front left)
8. front middle (front left)

On the ceiling:
Two spots between Atmos speakers are the front left and front right if in back row. (not centered as the speakers are not center to room)
Three spots closer to screen are the LCR reflection points if in front row.

Seem about right?

Which locations should I use for the four 2x4 244 panels on the wall? 
Seems like I almost need five panels with two adjoined behind that left surround speaker....


----------



## dnoonie

Stoked21 said:


> Marked first reflection points with mirror trick. *Back middle is MLP.*
> 
> On the ceiling:
> Two spots between Atmos speakers are the front left and front right if in back row. (not centered as the speakers are not center to room)
> Three spots closer to screen are the LCR reflection points if in front row.
> *
> Seem about right?
> 
> Which locations should I use for the four 2x4 244 panels on the wall?
> Seems like I almost need five panels with two adjoined behind that left surround speaker....*


Yes, that sounds right. Have you checked out http://www.avsforum.com/forum/19-de...on/1179128-deadwood-theater-comes-alive.html? I like the diffusion he used and the layout looks nearly identical. The diffusion is not quit as thick as some so it can be used closer the the MLP.

I think that your absorbers closest to the screen can certainly use scatter plates or QRD 7 diffusion and skip absorbers all together or put diffusion over absorption. The reason I say this now is that I might understand your layout better and if you're willing to compromise your front row a little for your MLP then diffusion will give you a more live sound, I see that you also may have the space to do this (or not, QRD 7s end up being about 7" thick or more if you put absorption behind them, you'll have to decide). 

Other thoughts, built in absorption, build nice looking frames 4" thick with nice trim over the edge and fill them then cover absorption with acoustic fabric, stain and finish or paint the trim. Look at the second picture in the deadwood theater first post, those are panels inside windows but they look nice, you can frame and trim built in panels or frame and trim regular hung panels. It depends on the look you want.

Cheers,


----------



## myfipie

dnoonie said:


> Their recommendation may be based on room size. What size is your room?
> 
> Nothing on the ceiling? I've found it very important to treat the ceiling. Do you have a drop down ceiling? If so the ceiling panels may be their own treatment. I did my ceiling as a step 2 process about a month after corners and first reflections. I wanted to experience/hear the difference before continuing.
> 
> I've been in rooms with scatter plates over absorption and (IMO) found that some distance is needed or imaging suffered 3 foot seemed to do it. Other folks experience/opinion is certainly different.
> 
> Cheers,


I always recommend something on the ceiling myself, but if the panels are going to interfere with the image on the screen then I have to skip it.


----------



## dnoonie

myfipie said:


> I always recommend something on the ceiling myself, but if the panels are going to interfere with the image on the screen then I have to skip it.


Hum. If I'm seeing the picture right, the ceiling reflections have been marked with green tape, cross beams would block the view as much or more than absorbers at those points, but if absorbers went over cross beams that could create a line of site issue.

Cheers,


----------



## raynist

myfipie said:


> I always recommend something on the ceiling myself, but if the panels are going to interfere with the image on the screen then I have to skip it.


Do you know of a good way to mount/hang a panel from a drop ceiling? I have 4 left over 242 panels and was going to put them on the ceiling but not sure how best to do it. I would want them as tight to the ceiling as possible.


----------



## dnoonie

raynist said:


> Do you know of a good way to mount/hang a panel from a drop ceiling? I have 4 left over 242 panels and was going to put them on the ceiling but not sure how best to do it. I would want them as tight to the ceiling as possible.


A drop ceiling scissor clamp/clip.

https://www.google.com/search?q=drop+ceiling+scissor+clamp&ie=utf-8&oe=utf-8

Check the weight rating. And I'd double check the drop ceiling anchors.

Cheers,


----------



## dnoonie

This style, http://www.pnta.com/scenic/hardware...LZJqmRA20QwRVmSjLTNU4kH0ETUHpzE9UMaAgxV8P8HAQ would allow you to use a nylon tie through it's eye that's built into the screw down that hold the two parts of the scissor tight.

Cheers,


----------



## artur9

raynist said:


> I would want them as tight to the ceiling as possible.


Don't they work better with a little bit of an air gap?


----------



## toofast68

artur9 said:


> Don't they work better with a little bit of an air gap?


So yes they should, but I assume your question was not really a question


----------



## raynist

artur9 said:


> Don't they work better with a little bit of an air gap?


The 242's already have a built in air gap. I only have 7ft ceilings so if they hang down too much they will interfere with the projector.


----------



## BllDo

raynist said:


> Do you know of a good way to mount/hang a panel from a drop ceiling? I have 4 left over 242 panels and was going to put them on the ceiling but not sure how best to do it. I would want them as tight to the ceiling as possible.


What size panels are they? Could you just replace a couple ceiling tiles with the 242 panels?


----------



## dnoonie

BllDo said:


> What size panels are they? Could you just replace a couple ceiling tiles with the 242 panels?


If your drop ceiling is 2x2 the dividers are removable with a little work to make a 2x4 opening.

Cheers,


----------



## raynist

dnoonie said:


> If your drop ceiling is 2x2 the dividers are removable with a little work to make a 2x4 opening.
> 
> Cheers,


Hi,

They are 2x2, I never thought of removing/modifying that section to be 2x4. The only problem might be that there is a bulkhead where the reflection point is so one of the 2x2 tiles is cut short. I may have to check the reflection points again.


----------



## dnoonie

raynist said:


> Hi,
> 
> They are 2x2, I never thought of removing/modifying that section to be 2x4. The only problem might be that there is a bulkhead where the reflection point is so one of the 2x2 tiles is cut short. I may have to check the reflection points again.


Thanks *BllDo* for the idea!

The big question is if it's size compatible.

With the drop ceilings I've worked with the dividers are held in place with a flat metal tab that is simply given a 45 degree twist to hold it in place. I've removed and reinstalled them with needle nose pliers.

Perhaps you know already...If you can use the panels in another place drop ceiling absorber tiles are available.

Cheers,


----------



## Curt D

*Reflective panel test*

Listening area is 19x13.5'. I put a 4" panel up at 1st reflection point on left wall with none on right side as it is open to the dining room. I also did contra lateral points (believe that's the term). It was too dead to me for 2 channel so I took contra Lat panels down. It sounds really good.
SO...I want to experiment put contra panels back up and take the 1st panel down and add a relective panel in the open space on the right to simulate a wall. Could I assume that I could use a 5/8" piece of drywall?


----------



## myfipie

raynist said:


> Hi,
> 
> They are 2x2, I never thought of removing/modifying that section to be 2x4. The only problem might be that there is a bulkhead where the reflection point is so one of the 2x2 tiles is cut short. I may have to check the reflection points again.


Most 2'x2' grids are more like 23.75"x23.75" so it will fit but you might have to modify a bit more. We do custom panels all the time that are sized to fit into grids.


----------



## myfipie

raynist said:


> The 242's already have a built in air gap. I only have 7ft ceilings so if they hang down too much they will interfere with the projector.


Whenever possible I do like for the client to have even more of a gap, but you are correct that a gap in built in. If you want to mount them flush then I recommend using L brackets. Basically it will go into the backing frame and the ceiling.


----------



## Wahoo_envy

Sorry if this has already been answered, but I couldn't find a clear cut answer. Is there any benefit to installing one inch acoustic panels with 1/4" plywood backing with an air gap? I need to hang 12 panels this weekend and I'm trying to determine the best mounting method. Thinking about just using Velcro.

Attached is a sample frame I have copied.


----------



## stucker

*Hanging Acoustic Panel Flush to Sloped Wall*

I need some advice on the best (and easiest) way to hang acoustic panels flush to a sloped wall. My room is the classic A-frame above the garage with knee walls and sloped walls on either side up to about a 3 foot across ceiling. Suggestions?


----------



## BasementBob

stucker said:


> I need some advice on the best (and easiest) way to hang acoustic panels flush to a sloped wall. My room is the classic A-frame above the garage with knee walls and sloped walls on either side up to about a 3 foot across ceiling. Suggestions?


Depending upon the slope and height, first thing that comes to mind would be to put round head screws into the ceiling, and sawtooth picture hangers on the panels


----------



## dnoonie

stucker said:


> I need some advice on the best (and easiest) way to hang acoustic panels flush to a sloped wall. My room is the classic A-frame above the garage with knee walls and sloped walls on either side up to about a 3 foot across ceiling. Suggestions?


As long as the surface is smooth enough (no popcorn ceiling) I think a regular z-clip (also called a French cleat) would work fine. You'd just need to use them on both top and bottom.
https://www.google.com/search?q=french+cleat&ie=utf-8&oe=utf-8
https://www.google.com/search?q=z-c...rwpbKAhUN7mMKHejVDkoQsAQIOg&biw=1354&bih=1330
http://www.acoustimac.com/acoustic-insulation-materials/installation-hardware/
http://www.atsacoustics.com/cat--Accessories--103.html

Cheers,


----------



## neverfinished94

myfipie said:


> There has been further testing (by us and others) done at labs over the years that have shown less dense, when making a panel (or filling the corner) will work better. But 703 stacked in the corner does also work pretty well.
> 
> 
> 
> You can do that and it will work well.


So in your opinion super chunk bass traps are beneficial? I plan on making 2 up front in my theater. I used Roxul safe n sound for my 2x4 panels with great results. Should I use the safe n sound for the bass traps as well or something else like OC 703? Or is there another material better for super chunks. Thanks in advance

Your replies in this forum are extremely informative & are greatly appreciated.


----------



## myfipie

neverfinished94 said:


> So in your opinion super chunk bass traps are beneficial? I plan on making 2 up front in my theater. I used Roxul safe n sound for my 2x4 panels with great results. Should I use the safe n sound for the bass traps as well or something else like OC 703? Or is there another material better for super chunks. Thanks in advance
> 
> Your replies in this forum are extremely informative & are greatly appreciated.


I have never used SNS material, but I would think if thick enough, it should work fine.


----------



## corradizo

Hi, long thread! How are you determining if you need diffusion or absorption and which frequencies need one or the other? REW Impulse? I'm hoping to find a guide on the subject if one exists.


----------



## dnoonie

corradizo said:


> Hi, long thread! How are you determining if you need diffusion or absorption and which frequencies need one or the other? REW Impulse? I'm hoping to find a guide on the subject if one exists.


Diffusion, what it's use boils down too is space and cost. It takes up more space and it costs more. A rule of thumb is to allow a foot of distance for every 1 inch of thickness of diffusion for proper diffusion to take place.

Cheers,


----------



## Bardia

Sorry, newbie question
If the entire room has carpets such as floor, walls and ceiling, would there still be a need for acoustical treatment such as boards?


----------



## erkq

Bardia said:


> Sorry, newbie question
> If the entire room has carpets such as floor, walls and ceiling, would there still be a need for acoustical treatment such as boards?


That's going to be a pretty dead sounding room. You're absorbing a lot of energy above a certain frequency and not a whole lot of bass. A room should have a combination of absorption over wide frequencies (which carpet does not do) and dispersion, just to start.


----------



## bass addict

I'm looking at adding 1" panels to my side walls from floor to sofit (narrower room so am sticking with 1") with the exception of the back wall which will be 2" inch. 

I'm just trying to find some direction on what to put where and how much. The room is 10' 8" x 22 x 9. The screen wall is already completely treated. I also have 2" thick acoustic panels arranged in a semi cloud pattern on the ceiling covering a 4 x 14 space with small gaps in between. 

From other builds I've looked through it appears people are using OC705 from about 4' up and at the front of the theater from floor to ceiling, and OC703 from 4' down. Is this too much deadening? 

Is it really going to matter between 703 and 705 due to only being 1" or should I still mix and match? Should I use 2" 705 for the back wall or something else?

If it matters, the speakers are AE TD15's for mains, Volts 10's for sides/rears/tops, and 8 SI 18" subs.


----------



## erwinfrombelgium

Bardia said:


> Sorry, newbie question
> If the entire room has carpets such as floor, walls and ceiling, would there still be a need for acoustical treatment such as boards?


A good absorbing material such as rock wool is very effective from 500 Hz and above if it's 2" thick. Even better is 4" because, you have guessed it, absorbs down to 250 Hz. So with carpet you probably only absorb everything above 1000 Hz. You change the sound and kill the sparkle. 

As erkq wrote best practice is a clever mixture of absorption, diffusion and reflexion. A multichannel HT needs more absorption than a stereo living room. A small room needs more absorption than a larger one.


----------



## corradizo

How do you know how low to absorb?


----------



## sdurani

corradizo said:


> How do you know how low to absorb?


As evenly across the range of your speakers as possible, otherwise you're using absorption as an elaborate tone control (rather than using lots of thin panels that will absorb the high frequencies, easier to turn the treble knob down).


----------



## erwinfrombelgium

Which means also as low as possible. Though it's not easy to use 2 feet thick absorbers with a 2 feet plenum....

Good practice can be to use 4" absorbers on the reflection zone, then measure with REW to find where the problems in the lower frequencies reside, then get specific panel bass absorbers (thinner than rock wool but only performant in specific frequencies) tot tackle the problem area.


----------



## Mfusick

Highs are the most easily absorbed so they are typically not the problem. Too much thin absorb and not enough treatment in the lower frequency can lead to a room that's too dead and too boomy ... In other words it sounds bad. 

Ideally you want your treatment to reach down low enough to provide vocal clarify and dialogue intelligence. If you kill some of the highs but fail to treat properly the lower mids which still echo you'll have issues with hearing dialogue... It's easily noticed. Not good.

Thinner treatments mean you need to pay more $ to get lower usable range from them, the panels that are the most premium cost more for a reason. Or you can go thicker. 

But a point of emphasis should be made that treating bass is different than treating the room for dialogue intelligibility and sound quality. You treat bass in a different way. Putting 12" on the walls is a poor way to deal with that, you can do other things that save the room size. So realistically you only need treatment down to about 200hz if you are treating for bass in an alternative manner.


----------



## bass addict

In addition to my post earlier. Wouldn't it make more sense for those of us dampening an entire room (floor to wall), to employ a combination of diffusion and absorption? 

I'm thinking something along the lines of; OC705 for the first third of the theater from floor to wall, with the second two thirds using OC703 up to 48", with OC705 being used in the upper 48" mixed with diffusion. 

Here is my idea for the upper half of the theater. I am building a box frame that will be attached to the wall and fitted with OC, alternating with MDF strips. I will cover with GOM. Please excuse my crude at work drawing (it was quick and easy). 

Or would strips of foil tape accomplish the same purpose? 

Small room 10'8" x 22 x 9'.


----------



## DonnyKerabatsos

Hey all, seeking advice as to whether I could get any improvement in the sound by treating my room. It sounds good to me, much better than my old den, which was open to a dining room, a stairwell, etc. 

Running a Denon 1913 AVR with a pair of NHT absolute towers, TwoC Center, and Absolute Wall surrounds. Sub is a Definitive Technology Prosub 1000 for now, but I intend to upgrade soon, likely to a Rhythmic LV12R. I did the sub crawl in the locations where the sub made sense aesthetically and for running the cable. Audyssey has been run. 

As you can see, I'm somewhat hamstrung as to where I can put panels due to lay out (windows) and decor, but I wasn't sure if corner bass traps, ceiling panels or rear wall panels might be of any appreciable benefit. Dimensions are 15'10" W x 17' L, with ceilings that slope up from 9' to 11' (from the front of the room, where the towers/TV are, to the back). 

Any suggestions appreciated.


----------



## DonnyKerabatsos

Hey all, seeking advice as to whether I could get any improvement in the sound by treating my room. It sounds good to me, much better than my old den, which was open to a dining room, a stairwell, etc. 

Running a Denon 1913 AVR with a pair of NHT absolute towers, TwoC Center, and Absolute Wall surrounds. Sub is a Definitive Technology Prosub 1000 for now, but I intend to upgrade soon, likely to a Rhythmic LV12R. I did the sub crawl in the locations where the sub made sense aesthetically and for running the cable. Audyssey has been run. 

As you can see, I'm somewhat hamstrung as to where I can put panels due to lay out (windows) and decor, but I wasn't sure if corner bass traps, ceiling panels or rear wall panels might be of any appreciable benefit. Dimensions are 15'10" W x 17' L, with ceilings that slope up from 9' to 11' (from the front of the room, where the towers/TV are, to the back). 

Any suggestions appreciated.

































Like to imgur album: https://imgur.com/a/1lP2J


----------



## erwinfrombelgium

Small absorbers between your TV and L/R front speakers.
Diffusion in the middle of the rear wall between the doors.
Large amounts of absorption on the ceiling: 4" thick with 4" plenum.
Bass traps in the corner between ceiling and rear wall.

Edit: why not making thicker absorbers towards the rear and hang them to the same height. So near the front wall there is none and near the rear wall it's maybe 1 foot thick with one foot distance.


----------



## Mfusick

bass addict said:


> In addition to my post earlier. Wouldn't it make more sense for those of us dampening an entire room (floor to wall), to employ a combination of diffusion and absorption?
> 
> I'm thinking something along the lines of; OC705 for the first third of the theater from floor to wall, with the second two thirds using OC703 up to 48", with OC705 being used in the upper 48" mixed with diffusion.
> 
> Here is my idea for the upper half of the theater. I am building a box frame that will be attached to the wall and fitted with OC, alternating with MDF strips. I will cover with GOM. Please excuse my crude at work drawing (it was quick and easy).
> 
> Or would strips of foil tape accomplish the same purpose?
> 
> Small room 10'8" x 22 x 9'.
> View attachment 1186602


You might be confusing reflection with diffusion. ?


----------



## bass addict

Mfusick said:


> You might be confusing reflection with diffusion. ?


Yeah, my terminology might be suspect, lol. I assumed incorporating MDF strips at varying heights might fall under diffusion (whereas the foil strips would be more reflection). 

I guess to clarify; a lot of the theater builds I've seen lately employ floor to ceiling treatments. I'm assuming they are 2" which would help tame a wider spectrum of the FR. 

In my case where I am using only 1" thick; would floor to ceiling treatments (2" back wall, 2" ceiling) create a dead, boomy sounding room? Should I incorporate more "reflection" into the panels?


----------



## bgtighe23

I just finished hanging my GIK 242 panels in Black. I honestly hate the hanging method used. They are really attractive panels either way. The other panels are from ATS Acoustic.

I placed an order with ATS for 2 red panels to swap with the white ones. Don't really like the color. I'll just put them behind the blackout curtains haha

PS: Ignore the center, I just also finished setting up those two media towers for the sake of being able to have a tower center and just grabbed an extra Infinity P363. I love the turnout. So much better than the entertainment center, IMO.


----------



## luisev

The ATS Z-Bars or any French cleat type designed mount to be the easiest way to mount panels to the wall.


----------



## bgtighe23

luisev said:


> The ATS Z-Bars or any French cleat type designed mount to be the easiest way to mount panels to the wall.
> 
> View attachment 1188978


And way more secure than the GIK panels.


----------



## DonnyKerabatsos

erwinfrombelgium said:


> Small absorbers between your TV and L/R front speakers.
> Diffusion in the middle of the rear wall between the doors.
> Large amounts of absorption on the ceiling: 4" thick with 4" plenum.
> Bass traps in the corner between ceiling and rear wall.
> 
> Edit: why not making thicker absorbers towards the rear and hang them to the same height. So near the front wall there is none and near the rear wall it's maybe 1 foot thick with one foot distance.


Thanks for the suggestions. I'm curious why I would want to essentially flatten the ceiling by hanging absorbers the way you suggest; I thought there was an acoustic benefit to no parallel room surfaces? 

I probably should've mentioned that I won't get approval to affix anything to the wood wall, so no panels on that front wall behind the tv and towers. 

If I install absorbers on the ceiling, would I benefit most by placing them at first reflection points relative to the mlp?


----------



## BasementBob

DonnyKerabatsos said:


> I thought there was an acoustic benefit to no parallel room surfaces?


Not really. From a mode's perspective it just makes them even less predictable.










If you manage to create a reflection free zone (RFZ) that has some advantages for stereo, but far less for a 7.1 system. But this presumes you've got left/right symmetry.

On the other hand, if you're building a laboratory highly reverberant sound chamber to test acoustic panel's absorption in, then lots of crazy angles for maximum diffusion is just fine.



DonnyKerabatsos said:


> would I benefit most by placing them at first reflection points


Usually, that's the 'biggest bang for the buck' placement


----------



## pletwals

DonnyKerabatsos said:


> Thanks for the suggestions. I'm curious why I would want to essentially flatten the ceiling by hanging absorbers the way you suggest; I thought there was an acoustic benefit to no parallel room surfaces?


Because various absorber thickness would make most use of the available height (higher towards the rear). Best use of a givven amount of absorbing material is to put it with the same distance (plenum) as the thickness of the material.

And this does not change the room surfaces BTW. Sound goes through the absorbers, partly (highs and mids) absorbed. The longer waves hit the surface and part of these go through the surface (the part that doesn't get absorbed inside the wall will be disturbing adjacent rooms) and part bounces back of which a part is absorbed by the absorber...


----------



## Stoked21

I have mixed feelings on my room treatments/advice...My room is L-shaped with a sitting area to the right of the HT portion and bar/bathroom/stairs next to that. Still under construction for a bit, so forgive mess in pics.

I was instructed to place four 244 panels on the left wall which covered FRP for L,C,R,and SR for both back-row-center MLP and front-row-center SLP. Also placed tri-traps in the back corner and 3 monster traps with range-limiter on back wall. It wasn't recommended, but I'm placing six 242 panels on the ceiling to cover the FRP for both middle seats as well. I was really surprised they didn't want me to put any diffusion or scatter plates in the room whatsoever. 

The front was completed prior to ordering and I had elected to run with CertainTeed anti-reflective ceiling tiles on the wall with the cheap/ineffective foam bass-traps in the corner...I know it's less than ideal material, but it works great with AT screen reducing reflectivity to less than 3% with an NRC of .75-.90 (I know NRC is kind of irrelevant). It also quieted the front of the room to an extreme making claps ring with a nasty ping in the back of the HT. 

*Pros:* After installing the GIK panels, the excellent sound-stage and imaging become significantly wider and deeper. I was blown away with music tests. My speakers were not highly localizable, but they disappeared even more. My bass extension is flat down to 12Hz up to about 28hz F3.

*Cons:* Then I made the mistake of running REW for my first time and noticed that Audyssey and/or the room was giving me some big dips at around 28 and 90Hz with a big mode at about 30-35hz. It also decided it wanted to cross my 80Hz F3 side surrounds at 200hz. I listened to a bunch of movie scenes that I'm intimately familiar with. I just feel like the mid-range or upper LF is missing the "pop" and "punch" now during action/fighting scenes. It also seemed to me that I could now hear reflections off the ceiling which were non-existent before. I find that instead of running movies at reference, I sometimes want to turn it 2-3 db above. Dialogue hasn't really suffered but maybe 5-10% of the time I wonder if it has, hence the increase above reference (though that could just be a quiet scene in the movie).

So maybe I'm conditioned to hearing all the reflections and non-linearities, thus expecting exaggerated FR in certain ranges. Maybe it's the placebo effect and seeing the REW graph below 200Hz, and turning the MV up higher, makes me feel like the room is over-damped. Now I wonder if adding the six extra panels on the ceiling is going to have a negative affect. And I wonder if the room really needs diffusion and perhaps I was steered wrong.


----------



## neverfinished94

I took a before and after waterfall graph and my DIY acoustic panels did a pretty good job taming frequencies above 100hz but below 100 is still a major issue. I want to do super chunk bass traps floor to ceiling up front but I am not 100% sure that is the best plan of action to target every thing below 100hz. I used roxul safe n sound for the existing panels. Should I continue to use the safe n sound? Should I use OC703? Should I use something else? Does anyone have any experience with super chunks that can point me in the right direction? I am worried that I will build these bass traps and not be happy with the results. Thanks in advance.


----------



## HopefulFred

Maybe your best first move is turn off Audyssey and set your crossovers where you want them, then reconsider.


----------



## myfipie

bgtighe23 said:


> I just finished hanging my GIK 242 panels in Black. I honestly hate the hanging method used. They are really attractive panels either way. The other panels are from ATS Acoustic.
> 
> .


Thanks for the feedback. We make the panel with a wire that you put across the back (eyehook to eyehook) Basically hang it like a picture frame so you are not putting a lot of holes in your wall. It would not be a problem to send with french cleats but that is just a lot more holes you have to drill into the wall. If you would like for me to send you some just send me an email through my company website.


----------



## myfipie

neverfinished94 said:


> I took a before and after waterfall graph and my DIY acoustic panels did a pretty good job taming frequencies above 100hz but below 100 is still a major issue. I want to do super chunk bass traps floor to ceiling up front but I am not 100% sure that is the best plan of action to target every thing below 100hz. I used roxul safe n sound for the existing panels. Should I continue to use the safe n sound? Should I use OC703? Should I use something else? Does anyone have any experience with super chunks that can point me in the right direction? I am worried that I will build these bass traps and not be happy with the results. Thanks in advance.


Safe N Sound is fine for super chunks. BTW you could use a bit more help below 100hz, but it is not looking as bad as you might think.


----------



## Stoked21

myfipie said:


> Thanks for the feedback. We make the panel with a wire that you put across the back (eyehook to eyehook) Basically hang it like a picture frame so you are not putting a lot of holes in your wall. It would not be a problem to send with french cleats but that is just a lot more holes you have to drill into the wall. If you would like for me to send you some just send me an email through my company website.


Bryan gave me the best advice on hanging these. Using the OOK type hooks like with picture frames. Instead of using the wire, I bought cheap small chain and s-hooks. I probably only spent $50 for chain, hangers and s-hooks for 7 panels. Makes it very easy to get them all level and they don't shift around unless bumped. I personally like the mounting method....Wire would have been a nightmare though.


----------



## Stoked21

So new REW measurement waterfalls after GIK treatment. They seemed to have helped out several db in the 30-40hz range.

LR Subs without Audyssey and without GIK










LR Subs Without Audyssey with GIK










LR Subs With Audyssey with GIK


----------



## bgtighe23

myfipie said:


> Thanks for the feedback. We make the panel with a wire that you put across the back (eyehook to eyehook) Basically hang it like a picture frame so you are not putting a lot of holes in your wall. It would not be a problem to send with french cleats but that is just a lot more holes you have to drill into the wall. If you would like for me to send you some just send me an email through my company website.


I honestly didn't realize you were on at AVS! I don't visit this thread too often. I would prefer the french cleats because they offer a more secure, and stable hanging method. The extra holes in the wall don't bother me at all because I know the panel is secure. If I ever need to patch one hole, patching another next to it isn't that bothersome.

I do think it would be cool if you offered different hanging methods and it could be chosen prior to placing the order during the checkout process. Even as something as simple as the "eyehook to eyehook" or french cleats. While it might add a minuscule amount of overall cost, including mounting hardware is something I would recommend. Assuming I had no hardware at all, I would need to purchase mounting hardware anyway so if the panels went up a couple dollars each, it seriously wouldn't be a deal breaker. 

Thanks for your time. I will try to get an email sent out today at some point with my forum name included.

EDIT: as someone else above mentioned (post 11205), the picture frame style (with wire) was a short nightmare. Especially to get the 3 panels even with each other.


----------



## AXLCMT

Is Cotton Batting ear level and above still stand for the side walls if I am going OC703 Bass Trapping up to hear level?

Maybe I am misinterpreting BigMouthinDC in his post reply to me regarding the question, but has the general consensus changed to 
"no cotton batting on the side walls anywhere" now. I thought it used to be that you wanted Cotton Batting on the side walls ear level to the ceiling to allow "diffusion" rather than absorption in combination with OC703 Bass Trapping floor to ear level.


----------



## raynist

bgtighe23 said:


> I honestly didn't realize you were on at AVS! I don't visit this thread too often. I would prefer the french cleats because they offer a more secure, and stable hanging method. The extra holes in the wall don't bother me at all because I know the panel is secure. If I ever need to patch one hole, patching another next to it isn't that bothersome.
> 
> I do think it would be cool if you offered different hanging methods and it could be chosen prior to placing the order during the checkout process. Even as something as simple as the "eyehook to eyehook" or french cleats. While it might add a minuscule amount of overall cost, including mounting hardware is something I would recommend. Assuming I had no hardware at all, I would need to purchase mounting hardware anyway so if the panels went up a couple dollars each, it seriously wouldn't be a deal breaker.
> 
> Thanks for your time. I will try to get an email sent out today at some point with my forum name included.
> 
> EDIT: as someone else above mentioned (post 11205), the picture frame style (with wire) was a short nightmare. Especially to get the 3 panels even with each other.


I hung 6 panels on my back wall, it was a royal pain to get them all the same hieght. The wire way is very imprecise. My fingers were bleeding from undoing each one 5 times to get it even, then you bump it, or a guest does and they are uneven again. Would have preferred an extra hole in the wall per panel and French cleats. I may still take them all down and do French cleats. Hung 16 panels in total.


----------



## Stoked21

raynist said:


> I hung 6 panels on my back wall, it was a royal pain to get them all the same hieght. The wire way is very imprecise. My fingers were bleeding from undoing each one 5 times to get it even, then you bump it, or a guest does and they are uneven again. Would have preferred an extra hole in the wall per panel and French cleats. I may still take them all down and do French cleats. Hung 16 panels in total.


Man...You really need to go to Lowes. Don't use the wire.

Buy a little box of black chain. I think it's rated like 10lbs but that's consider torque etc. The panels hang straight down and even a Monster Bass trap is only like 15 lbs or something. So don't worry about the rating. The chain isn't going to break and it takes 2 big pairs of vice grips to even open a link. 

A box of about 20 feet will cost around $10 and do about 5-6 panels. Buy some small s-hooks for about $0.25 each while you're there and a few packs of those angled hangers like OOK. My 7 panels are rock solid, perfectly level and took maybe 1 hour to hang 7 panels. They can tilt at an angle if bumped. If they do, just move left or right one link on the chain. I even have one hung on a door and when I shut the door, it stays straight.

I literally just put the same number of links on all 7 panels. Marked 6' up the wall where I wanted the panels. Hammered in 1 OOK hook and hung the panel. Everyone was straight and none needed redone. It's really that simple.


----------



## raynist

Stoked21 said:


> Man...You really need to go to Lowes. Don't use the wire.
> 
> Buy a little box of black chain. I think it's rated like 10lbs but that's consider torque etc. The panels hang straight down and even a Monster Bass trap is only like 15 lbs or something. So don't worry about the rating. The chain isn't going to break and it takes 2 big pairs of vice grips to even open a link.
> 
> A box of about 20 feet will cost around $10 and do about 5-6 panels. Buy some small s-hooks for about $0.25 each while you're there and a few packs of those angled hangers like OOK. My 7 panels are rock solid, perfectly level and took maybe 1 hour to hang 7 panels. They can tilt at an angle if bumped. If they do, just move left or right one link on the chain. I even have one hung on a door and when I shut the door, it stays straight.
> 
> I literally just put the same number of links on all 7 panels. Marked 6' up the wall where I wanted the panels. Hammered in 1 OOK hook and hung the panel. Everyone was straight and none needed redone. It's really that simple.


Sounds way better than what I did!


----------



## nandkisham

*Front Wall acoustic treatment*

What is the optimal way to treat the Front wall?

1" OC select sound black acoustic blanket (Link) 
vs
2" OC 703 

LCR speakers are towers behind AT screen (2ft) and not in-wall. 

thoughts...


----------



## myfipie

raynist said:


> I hung 6 panels on my back wall, it was a royal pain to get them all the same hieght. The wire way is very imprecise. My fingers were bleeding from undoing each one 5 times to get it even, then you bump it, or a guest does and they are uneven again. Would have preferred an extra hole in the wall per panel and French cleats. I may still take them all down and do French cleats. Hung 16 panels in total.


I have had customers cut the wire too two short pieces, attach to the eyehook, make a loop on the other end then hang that on a hook on the wall. I may give this some thought and come up with other options for customers though. The french cleat is great but it still will not be flush to the wall.


----------



## BllDo

I used these Canvas Hangers to hang my DIY panels. If you have a small gap at the back to fit the hanger, the panel will fit flush to the wall. They worked very well. I shot a laser level across my room and got all the panels hung perfectly in one shot.


----------



## erwinfrombelgium

nandkisham said:


> What is the optimal way to treat the Front wall?
> 
> 1" OC select sound black acoustic blanket (Link)
> vs
> 2" OC 703
> 
> LCR speakers are towers behind AT screen (2ft) and not in-wall.
> 
> thoughts...


1" is never enough. Hence the 2", it wil deal with one lower octave. 4" is better!


----------



## dnoonie

myfipie said:


> I have had customers cut the wire too two short pieces, attach to the eyehook, make a loop on the other end then hang that on a hook on the wall. I may give this some thought and come up with other options for customers though. The french cleat is great but it still will not be flush to the wall.


For precision hanging there is a product called "loop line", it's knotted at precise intervals for even hanging and good for 25lb per each length (quit a bit more actually, I've hung about 50lb or more from a single length, I'd stick with the rating for overhead hanging though). I'm not sure how well it would work for this but I've used it for hanging a lot of different things (besides the posters it's marketed for hanging) and it works great, much easier than measuring and trying to guess.

http://clik-clik.com/loopline/, is one brand/maker, it's available at staging and event outfitters mail order, if you live or work in/near a big city there may be a handy place to pickup at a will call desk.

Cheers,


----------



## boifido

I was hoping to get some input on my room treatment progress. So far I've built corner absorbers for the front of the room. Unfortunately the back has a door and a counter, so I can't built a matching pair for rear room symmetry. It's my first audio system so learning all about speaker specs, then measurements and room treatment has been quite an exciting journey over the last few months.

The traps have a leg length of 23 inches, and a hypotenuse of about 32.5". I used R20 insulation. I saw something about R30 being ~5000 rayls, so I'm hoping R20 is in the range of 3000. I put a single layer clear garbage bag cover around the frame to contain the insulation and then covered in a pretty light fabric. I'm hoping they aren't thick enough to impede the effectiveness. Very unscientifically, I put the bag over my head with music playing and didn't notice any difference in sound. 

I've attached a link to my REW file with all the measurements. They were taken in exactly the same position with an un-moved microphone. I'd appreciate any input on whether the changes I'm seeing are acceptable for absorbers this size. They seem to have made some difference in the waterfall decay down to about 60hz. 

Also, any input on further treatments would be appreciated. My plan next is to build absorbers to treat the front wall first reflections and hopefully reduce SBIR. The center channel becomes a mess in the 200hz and lower region too.

I need to learn how to read/take ETC's and also see if I can troubleshoot the 70hz null issue on the left speaker. It exists pretty much anywhere I move the speaker, but isn't on the right speaker even though everything is set up exactly symmetrical. It is a basement room and the left wall is the edge of the house, so concrete backed I assume, whereas the right has another room adjacent. I'm thinking that could be the cause. 

System is Polk LSiM 703/705/706c. 

Thanks!

MDAT File:
REW MDAT File hosted on One Drive

Photo and single measurement should be attached to the post.


----------



## pletwals

I am not the specialist, but I reckon you also would benefit not only from front wall treatment but also from side wall and ceiling treatments for first reflections. 

Maybe you can make specific panel absorbers for the 70 Hz problem?


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## sdurani

boifido said:


> I need to learn how to read/take ETC's and also see if I can troubleshoot the 70hz null issue on the left speaker. *It exists pretty much anywhere I move the speaker*, but isn't on the right speaker even though everything is set up exactly symmetrical.


Have you tried swapping speakers?


----------



## boifido

pletwals said:


> I am not the specialist, but I reckon you also would benefit not only from front wall treatment but also from side wall and ceiling treatments for first reflections.
> 
> Maybe you can make specific panel absorbers for the 70 Hz problem?


Yes. And also the concrete floor is likely a huge issue. I'm aiming to do one area at a time so I can learn and improve my DIY skills as I go along. I have pretty much no experience with constructing stuff. The reason for doing front wall next is I have enough room depth to make the panels thick enough to absorb at least down to the transition frequency. The side wall will need to be thinner to avoid making the room width smaller than it already is. So ideally would use a more advanced technique.

Room is roughly 11'(w)*26'(l)*7.5'(h) so I'm already feeling the squeeze for width and height.





sdurani said:


> Have you tried swapping speakers?


 No they're about 80 pounds and unwieldy so it would be a pain to move them all the way around the desk. A sharp null didn't seem like a speaker issue to me. Especially when I have 1 or 2 measurements without it. I think when it was placed either directly against the walls in corner or far away from the sidewall. So it's likely a boundary interference issue, or desk. That issue is annoying but less important since I can cross over to subs above it which have flat response with no nulls.


----------



## bgtighe23

myfipie said:


> I have had customers cut the wire too two short pieces, attach to the eyehook, make a loop on the other end then hang that on a hook on the wall. I may give this some thought and come up with other options for customers though. The french cleat is great but it still will not be flush to the wall.


But they stay put during LFE/ULF scenes of HT and music. Mine constantly shift to one side, then, due to physics, continue falling to one side. The far left panel fell against the ATS panel, so they didn't completely fall over.

ATS uses 4 total french cleats, but they are about half the size of the ones y'all stock up on (assuming they are the same as the ones I requested after having these issues). They also include a template and hardware for mounting. They are a millimeter or two from the wall at the most. They don't use slanted french cleats.

One of my wires broke today. About a quarter way from the left eye-hook if you're facing the back of the panel. Still can't figure out how - they're mounted using smooth nails


----------



## HiFiGuy1

erwinfrombelgium said:


> 1" is never enough. Hence the 2", it wil deal with one lower octave. 4" is better!


Interestingly, Dennis Erskine said (13 years ago in this thread) to cover the front wall with 1" InsulShield, and that 1" InsulShield is preferable over 2" treatment. Said the 2" is too absorptive. I am paraphrasing.


----------



## bass addict

HiFiGuy1 said:


> Interestingly, Dennis Erskine said (13 years ago in this thread) to cover the front wall with 1" InsulShield, and that 1" InsulShield is preferable over 2" treatment. Said the 2" is too absorptive. I am paraphrasing.


It's interesting how things have changed over the years. When building my first theater the advice was; 1" linacoustic on the front and sidewalls up to just above ear level, and poly batting on the rest of the walls above that. 

Fast forward to today and most will recommend a minimum of 2" on the front wall and 4" plus on the rear wall, with 2" on the sidewalls from floor to ceiling with some diffusion and reflection points mixed in.


----------



## myfipie

bgtighe23 said:


> But they stay put during LFE/ULF scenes of HT and music. Mine constantly shift to one side, then, due to physics, continue falling to one side. The far left panel fell against the ATS panel, so they didn't completely fall over.
> 
> ATS uses 4 total french cleats, but they are about half the size of the ones y'all stock up on (assuming they are the same as the ones I requested after having these issues). They also include a template and hardware for mounting. They are a millimeter or two from the wall at the most. They don't use slanted french cleats.
> 
> One of my wires broke today. About a quarter way from the left eye-hook if you're facing the back of the panel. Still can't figure out how - they're mounted using smooth nails


If you would like please feel free to send me a email and I can send out some french cleats. Not a problem at all.


----------



## bgtighe23

myfipie said:


> If you would like please feel free to send me a email and I can send out some french cleats. Not a problem at all.


I explained in the post you quoted me on that I had already requested some after having these issues. They have been delivered, will be installed this weekend.


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## MarkLT1

I haven't gotten any feedback in my build thread, so I figure I'll ask here as well. I am currently working on my first theater. Rather than being a dedicated room, it is more of a nook off a living room. Obviously not ideal at all for sound, but sometimes you just need to make the best of what you have.

The room is 12' from the rear wall to the screen, and 10'11" wide, and has about a 6'6" opening along one of the walls. Now I realize I won't ever be getting an amazing sounding theater, but I am hoping I can improve the audio quality somewhat with the use of some strategically placed acoustic treatments. I would like to have all the walls lined with fabric panels, but am guessing that the optimal layout may have sound absorbing material behind some of the panels, but not others. I have my list of questions in my build thread, here. Further up in the thread, there is a more detailed drawing of the room layout with dimensions, etc. Any feedback would be greatly appreciated (feel free to answer here, or in my build thread).


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## DonnyKerabatsos

So, after discussions with the WAF counsel and looking at locations of can lights and smoke detectors, it looks like the only things I could swing in the room would be (diffuser) panels on the back wall between the doors and maybe bass traps higher in the rear corners. Will doing only that be worthwhile/make a noticeable difference?



DonnyKerabatsos said:


> Hey all, seeking advice as to whether I could get any improvement in the sound by treating my room. It sounds good to me, much better than my old den, which was open to a dining room, a stairwell, etc.
> 
> Running a Denon 1913 AVR with a pair of NHT absolute towers, TwoC Center, and Absolute Wall surrounds. Sub is a Definitive Technology Prosub 1000 for now, but I intend to upgrade soon, likely to a Rhythmic LV12R. I did the sub crawl in the locations where the sub made sense aesthetically and for running the cable. Audyssey has been run.
> 
> As you can see, I'm somewhat hamstrung as to where I can put panels due to lay out (windows) and decor, but I wasn't sure if corner bass traps, ceiling panels or rear wall panels might be of any appreciable benefit. Dimensions are 15'10" W x 17' L, with ceilings that slope up from 9' to 11' (from the front of the room, where the towers/TV are, to the back).
> 
> Any suggestions appreciated.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Like to imgur album: https://imgur.com/a/1lP2J


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## asarose247

your input requested, please

I'm planning a "cloud" for 2 layers of 3" roxul inside my ATMOS trestle set-up. could be as large as about 40 ft^2

It will be about 15" ahead of my aimed at MLP Volts 6's and cover the entire space, almost , inside the trestle.
Because it's going to be broadband , I was thinking of using (black) fluorescent lighting egg crate panels to provide the roxul support between the supportive rails but there will be a layer of AT fabric underneath, for aesthetics, reflected light mitigation and fiber containment.

I've made regular 2" 703 panels with no frontal surface or minimal surface area compromise but they were not to be broad band

the egg crate panels have 1/2" opening and about 1/2" depth and the lattice structure of egg crate design will "reduce" the total surface area of the bottom layer exposed to reflected sound

but because the purpose is broadband, is that surface area reduction and the reflective surfaces of the lattice itself a significant factor of effectiveness reduction?

or should I be imagineering some other less obstructed thing

has anyone used egg crate "lenses" in this manner?


----------



## asarose247

your input requested, please

I'm planning a "cloud" for 2 layers of 3" roxul inside my ATMOS trestle set-up. could be as large as about 40 ft^2

It will be about 15" ahead of my aimed at MLP Volts 6's and cover the entire space, almost , inside the trestle.
Because it's going to be broadband , I was thinking of using (black) fluorescent lighting egg crate panels to provide the roxul support between the supportive rails but there will be a layer of AT fabric underneath, for aesthetics, reflected light mitigation and fiber containment.

I've made regular 2" 703 panels with no frontal surface or minimal surface area compromise but they were not to be broad band

the egg crate panels have 1/2" opening and about 1/2" depth and the lattice structure of egg crate design will "reduce" the total surface area of the bottom layer exposed to reflected sound

but because the purpose is broadband, is that surface area reduction and the reflective surfaces of the lattice itself a significant factor of effectiveness reduction?

or should I be imagineering some other less obstructed thing

has anyone used egg crate "lenses" in this manner?


----------



## keenly

The right side of my room is dominant. What should I do? I already have left speakers 2db louder.


----------



## HopefulFred

keenly said:


> The right side of my room is dominant. What should I do? I already have left speakers 2db louder.


Make sure the speakers are working the same. Maybe swap them and recheck.

Assuming they are the same and working properly, I'm guessing the first lateral reflection for the right speaker off the right wall needs to be absorbed. It's tough to know without more information.


----------



## xxrb1

*2016 state of the art - AT screen - front wall treatment*

Looking to get the last best practices about front wall treatment for an AT screen.

So far I got the following reading many posts here and elsewhere:

- 2 layers of 1"/2" linacoustic with x mil of plastic between
- 4 or more inch of Roxul mineral
- You need more thickness, more to come from Jeff with no further message 
- Bass trap on corners

I did not put a summary of the theory about wave length and thickness of insulation in magnitude of foot. That is a good read for a late night, but I have yet to see a thread with walls thick as 10 ft.


So, feel free to post what we should call the best practices for front wall treatment in an AT screen configuration. We might have more than one answer or disagreement, fine. Please no answer such as it depends. I read many build threads and they all do about the same. The devil is in the details, I agree. I will argue there is a common base we can call best practices and then you can always add up with diminishing return to price. I have in mind as common base a room with double drywall with green glue or equivalent, double OSB floating on some sort of mat. Stage filled with insulation , sand, or nothing, whatever.... (see long post about it ). Some kind of soffits more or less stuffed with sound attenuation product such as OC 700 series, pink fiberglass.

Last point, do not forget about the DYI focus on many people here.

Thanks


----------



## asoofi1

@xxrb1 I've been holding out on treating my room fully due to a back wall extension, but have been keeping an eye out on the same question... so far it seems the linacoustic sandwich up front is the most common start...and no more than 25% room coverage of absorption/diffusion in the rest of the HT....at least this is what I keep coming across....there may be newer threads I haven't seen...but a linacoustic front wall is 80% of HTs I've seen people post. Of course, getting a professional treatment plan for your room would be best...and may be a worth investment over any guess work.


----------



## xxrb1

asoofi1 said:


> @xxrb1 I've been holding out on treating my room fully due to a back wall extension, but have been keeping an eye out on the same question... so far it seems the linacoustic sandwich up front is the most common start...and no more than 25% room coverage of absorption/diffusion in the rest of the HT....at least this is what I keep coming across....there may be newer threads I haven't seen...but a linacoustic front wall is 80% of HTs I've seen people post. Of course, getting a professional treatment plan for your room would be best...and may be a worth investment over any guess work.


Thanks asoofi1 for your reply,

Agree that the overall room treatment needs something dedicated to the room structure. Designing walls/ceiling/floor treatments might need some calculation. However, the back of the screen wall seems something really basic in term of treatment for 90% of the case as you mentioned.

By the way, Linacoustic can also be replaced by Knauf Sonix XP which according to the forum might be cheaper and easier to find.


----------



## asoofi1

xxrb1 said:


> Thanks asoofi1 for your reply,
> 
> Agree that the overall room treatment needs something dedicated to the room structure. Designing walls/ceiling/floor treatments might need some calculation. However, the back of the screen wall seems something really basic in term of treatment for 90% of the case as you mentioned.
> 
> By the way, Linacoustic can also be replaced by Knauf Sonix XP which according to the forum might be cheaper and easier to find.


The front being 'dead' has definitely been a baseline...can't go wrong with that as a start. I had not heard of Kaufman Sonic XP...will have to look into it. The a Linacoustic 100'x48" roll 1" is going for $150-160 in my area.


----------



## Mfusick

http://bondedlogic.com/pdf/denim-insulation/UltraTouch-Denim-Spec-Sheet.pdf


----------



## HTPCat

Would the knauf smooth board 2" 1.6lb 24"x48" work as well as the linacoustic on the front wall behind a AT screen? 

Sent from my SM-T230NU using Tapatalk


----------



## xxrb1

Mfusick said:


> http://bondedlogic.com/pdf/denim-insulation/UltraTouch-Denim-Spec-Sheet.pdf


Thicker than Linacoustic or Sonic XP, but looks very good in term of sound attenuation properties. Looks also very good in term of air breathing quality after installation.

Any idea in term of pricing compare to the 2 others?

Forget, you have them at HD


----------



## keenly

HopefulFred said:


> Make sure the speakers are working the same. Maybe swap them and recheck.
> 
> Assuming they are the same and working properly, I'm guessing the first lateral reflection for the right speaker off the right wall needs to be absorbed. It's tough to know without more information.


Hi

all that has been done. Speakers are wired correctly. The problem is particularly noticeable with rear speakers. The right side which is dominant is closer to the wall, rear speaker is more enclosed. See pics.

My room is not symmetrical. Right sound has a cupboard at back and window in middles, which are presented in an hexagon shape. I could only fill in one corner at back with bass trap(I need to start another thread for help with that).

cheers


----------



## BasementBob

Keenly: 
I suppose you could use absorption to take care of the high frequency reflection problems, and equalize each speaker independently to deal with the low frequency wall boost issue. No one's is ever perfect, and even with the previous sentence yours there will remain worse than many -- unless you can commit to left-right symmetry.


----------



## asoofi1

Mfusick said:


> http://bondedlogic.com/pdf/denim-insulation/UltraTouch-Denim-Spec-Sheet.pdf


For the front wall instead of duct liner sandwich?


----------



## asoofi1

xxrb1 said:


> Thanks asoofi1 for your reply,
> 
> Agree that the overall room treatment needs something dedicated to the room structure. Designing walls/ceiling/floor treatments might need some calculation. However, the back of the screen wall seems something really basic in term of treatment for 90% of the case as you mentioned.
> 
> By the way, Linacoustic can also be replaced by Knauf Sonix XP which according to the forum might be cheaper and easier to find.


Just FYI: found out Sonix XP is now known as Atmosphere. I'm still waiting to hear back about pricing from a local dealer.


----------



## keenly

Should I put acoustic panels behind all speakers, against walls?


----------



## keenly

BasementBob said:


> Keenly:
> I suppose you could use absorption to take care of the high frequency reflection problems, and equalize each speaker independently to deal with the low frequency wall boost issue. No one's is ever perfect, and even with the previous sentence yours there will remain worse than many -- unless you can commit to left-right symmetry.


What does LF wall boost mean?


----------



## HopefulFred

Bob is referring to the effective increase in sensitivity and higher output you get in the bass region by placing speakers near walls. (Look into baffle step compensation if you want to get into some technical details.)


----------



## keenly

HopefulFred said:


> Bob is referring to the effective increase in sensitivity and higher output you get in the bass region by placing speakers near walls. (Look into baffle step compensation if you want to get into some technical details.)


It is literally unavoidable, should I try and fit some Rockwool behind it?


----------



## HopefulFred

Does your processor/receiver have an auto-calibration routine? It's probably sufficient for the low frequency concern, as Bob suggested. If you can locate the surface where high frequency reflection may be occurring, absorption is appropriate (again, as Bob suggested).


----------



## asoofi1

xxrb1 said:


> Thicker than Linacoustic or Sonic XP, but looks very good in term of sound attenuation properties. Looks also very good in term of air breathing quality after installation.
> 
> Any idea in term of pricing compare to the 2 others?
> 
> Forget, you have them at HD


Turns out Sonic XP, now known as Atmosphere, is over twice as expensive as Linacoustic in my area.

For 100' roll, a local dealer is charging $331 for the Atmosphere vs $160 for Linacoustic


----------



## candyisdandy

I sit against rear wall; my head is 21 inches away from it. I moved the couch as far as I can and that's the farthest I can do in my small room.

I'm thinking of buying 48x24x2 DMD 422 acoustic panel from ACOUSTIMAC. I will be placing it horizontally on back wall behind me, would that be a good idea since I sit close to back wall? 

Also, which would I benefit better in the panel core type: Roxul Rockboard Core (free), or Owens Corning 703 (additional 3 dollars)? I know nothing about this so care to shed any light.


----------



## dnoonie

candyisdandy said:


> I sit against rear wall; my head is 21 inches away from it. I moved the couch as far as I can and that's the farthest I can do in my small room.
> 
> I'm thinking of buying 48x24x2 DMD 422 acoustic panel from ACOUSTIMAC. I will be placing it horizontally on back wall behind me, would that be a good idea since I sit close to back wall?
> 
> Also, which would I benefit better in the panel core type: Roxul Rockboard Core (free), or Owens Corning 703 (additional 3 dollars)? I know nothing about this so care to shed any light.


I think 4" would work best for the back wall, back walls get a lot of bass build up. I have 4" nearly entirely covering the back wall and even 4" over 4" in places and I still have bass build up on the back wall. If you haven't treated corners with bass traps and first reflection points (including the ceiling) yet that would be a better place to start. Here's a good video, http://www.gikacoustics.com/video-early-first-reflection-points/, on first reflection points. I use a tall mirror so that I can find reflection points by myself. Ultra cheep ones like this, http://www.kmart.com/full-length-do...TTHwDbkN-wL1FZsTUCpbmoySbYSQRiSfGkaAjga8P8HAQ, are often made of polished metal not glass and work great for this type of thing.

I have Acoustimac panels and like them, the hanging system with the Z-clips/French cleat works very well. To create a plenum I hang on a mounting strip.

Cheers,


----------



## candyisdandy

dnoonie said:


> I think 4" would work best for the back wall, back walls get a lot of bass build up. I have 4" nearly entirely covering the back wall and even 4" over 4" in places and I still have bass build up on the back wall. If you haven't treated corners with bass traps and first reflection points (including the ceiling) yet that would be a better place to start. Here's a good video, http://www.gikacoustics.com/video-early-first-reflection-points/, on first reflection points. I use a tall mirror so that I can find reflection points by myself. Ultra cheep ones like this, http://www.kmart.com/full-length-do...TTHwDbkN-wL1FZsTUCpbmoySbYSQRiSfGkaAjga8P8HAQ, are often made of polished metal not glass and work great for this type of thing.
> 
> I have Acoustimac panels and like them, the hanging system with the Z-clips/French cleat works very well. To create a plenum I hang on a mounting strip.
> 
> Cheers,


Thank you. I don't see any acoustic panels with 4 inch on acoustimac. Should I just get a bass trap (48x42x4) and place that horizontally on back wall behind me or that wouldn't work?


----------



## dnoonie

candyisdandy said:


> Thank you. I don't see any acoustic panels with 4 inch on acoustimac. Should I just get a bass trap (48x42x4) and place that horizontally on back wall behind me or that wouldn't work?


Yes, you got it, that's what I meant, sorry for the confusion, when acoustic absorber panels are 4" or more folks call them bass traps.

Cheers,


----------



## candyisdandy

dnoonie said:


> Yes, you got it, that's what I meant, sorry for the confusion, when acoustic absorber panels are 4" or more folks call them bass traps.
> 
> Cheers,


Cool. Hey, one more thing. Does panel size matter? like if I wanted to place them on side wall of speaker like 12x24x2, 12x12x2, or would I need 12x48x2 for side wall? 

I have no acoustic treatment in room right now.


----------



## artur9

candyisdandy said:


> I have no acoustic treatment in room right now.


For my room putting up thick absorption on the back wall behind me helped the most with dialog. If you can put 4" back there with an air gap that would help a great deal.


----------



## dnoonie

candyisdandy said:


> Cool. Hey, one more thing. Does panel size matter? like if I wanted to place them on side wall of speaker like 12x24x2, 12x12x2, or would I need 12x48x2 for side wall?
> 
> I have no acoustic treatment in room right now.


For side placement check the video link I posted for first reflection points. Size helps, space limitations such as doors, windows etc can limit that, most of my panels are 2'x4'.

Cheers,


----------



## candyisdandy

dnoonie said:


> For side placement check the video link I posted for first reflection points. Size helps, space limitations such as doors, windows etc can limit that, most of my panels are 2'x4'.
> 
> Cheers,


Thanks.
I've decide to make my own panels. Do you know this fabric would work: (copy paste on Amazon) 1 X Polyester Cotton Broadcloth BLACK Fabric? It's 3.27 a yard.


----------



## dnoonie

candyisdandy said:


> Thanks.
> I've decide to make my own panels. Do you know this fabric would work: (copy paste on Amazon) 1 X Polyester Cotton Broadcloth BLACK Fabric? It's 3.27 a yard.


I looked at the fabric and I have no idea of it's acoustic properties.

I've used the DMD fabric from acoustimac and I like it a lot, extremely durable, http://www.acoustimac.com/dmd-acoustic-fabric.

Also note that acoustimac has 2" *Acoustimac Mineral Wool* http://www.acoustimac.com/clr-mnw1280, on closeout. For 4" just use 2 of the sheets.

Cheers,


----------



## Kamikaze13

Has anyone here used 2" Akousti-liner R from Manson Insulation?
I'm planning on using it for my front and side wall treatment as I can't get OC703 in my area.


----------



## candyisdandy

So my first reflection point has a big sliding glass window, should I mount acoustic panel (24x36) on stand and if so how do I build it? Also, I have a heater vent on floor where it would be, would that be safe. The fabric is not fire resistant? The insulation I'm using on acoustic panel is Roxul rock board 60.

The room is 10x12x8.


----------



## dnoonie

candyisdandy said:


> * 1. So my first reflection point has a big sliding glass window, should I mount acoustic panel (24x36) on stand and if so how do I build it?* Also, I have a 2. *heater vent *on floor where it would be, would that be safe. The fabric is not fire resistant? The insulation I'm using on acoustic panel is Roxul rock board 60.
> 
> The room is 10x12x8.


1. Exactly, https://www.google.com/search?q=acoustic+gobo&ie=utf-8&oe=utf-8, some are pretty simple and effective looking.

2. I'm not really comfortable making a recommendation. Paper has a flash point of around 450F if I remember right, https://www.google.com/search?q=paper+flash+point&ie=utf-8&oe=utf-8, yep, I measured the temp coming out of my heat register at 135F after running for 30min. You'll have to be the judge of what's safe and check the materials that you are using. Acoustic fabric and insulation usually has a fire rating.

Cheers,


----------



## myfipie

Kamikaze13 said:


> Has anyone here used 2" Akousti-liner R from Manson Insulation?
> I'm planning on using it for my front and side wall treatment as I can't get OC703 in my area.


Do you have a link? Looks like Knauf to me, which will work VERY WELL!


----------



## myfipie

candyisdandy said:


> So my first reflection point has a big sliding glass window, should I mount acoustic panel (24x36) on stand and if so how do I build it? Also, I have a heater vent on floor where it would be, would that be safe. The fabric is not fire resistant? The insulation I'm using on acoustic panel is Roxul rock board 60.
> 
> The room is 10x12x8.


Yes I would treat that area. Can't help much with how to build it but I don't think I would worry about the heater. People put chairs, couches and so on around floor vents all the time.


----------



## Kamikaze13

myfipie said:


> Do you have a link? Looks like Knauf to me, which will work VERY WELL!


http://www.imanson.com/pages/en/products/products-by-category.php?cid=2&pid=9

I'm guessing I would put the black mat face against the wall?


----------



## myfipie

Kamikaze13 said:


> http://www.imanson.com/pages/en/products/products-by-category.php?cid=2&pid=9
> 
> I'm guessing I would put the black mat face against the wall?


I don't know much about that black matt, but yes I would face it to the wall if you want the panel to absorb upper frequencies also. It might work as a membrane if facing the room, if you are also making bass traps for corners. Like I said though I have never worked with that finish.


----------



## Kamikaze13

myfipie said:


> I don't know much about that black matt, but yes I would face it to the wall if you want the panel to absorb upper frequencies also. It might work as a membrane if facing the room, if you are also making bass traps for corners. Like I said though I have never worked with that finish.


I peeled the black mat face a bit and it's very porous and reminds me of a lot of house wrap, so I assume that would be fine facing outwards? It's just nicer with the black facing out.


----------



## healthnut

Greetings acoustical masters! I'm slogging my way through this thread, though I'm still in 2006, so if this has been answered previously, my apologies. Just got a new killer sub, a Deep Sea Sound Mariana Max. Awesome sub, maybe a little too good, since it's rattling glassware in the kitchen above, hence my problem: I've packed Safe n Sound in the ceiling, there is duct work that goes from basement (where the theater room is) also. Short of turning the sub volume way down, what else can I do? I could add more safe n sound, since it didn't completely fill the ceiling (it's a drop ceiling), but the little woman's not very accepting of what all this bass is doing in the kitchen. Any suggestions greatly appreciated.


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----------



## dnoonie

healthnut said:


> ...it's rattling glassware in the kitchen above, hence my problem: I've packed Safe n Sound in the ceiling, there is duct work that goes from basement (where the theater room is) also. Any suggestions greatly appreciated.


What other treatments are in the room? What's the room size? Closed room or open? Concrete walls? 

Cheers,


----------



## healthnut

dnoonie said:


> What other treatments are in the room? What's the room size? Closed room or open? Concrete walls?
> 
> Cheers,



Thanks for the prompt response. I have bass traps (GIK) in 3 corners as well as a total of 6 first reflection panels (3 on each wall), the room is L shaped, with the theater comprising the vertical part, otherwise, closed off. the room size is 24" by 14" by 7", concrete floor and concrete walls on one outside length wall and in the rear, rest is drywall. 


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----------



## dnoonie

healthnut said:


> Thanks for the prompt response. I have bass traps (GIK) in 3 corners as well as a total of 6 first reflection panels (3 on each wall), the room is L shaped, with the theater comprising the vertical part, otherwise, closed off. the room size is 24" by 14" by 7", concrete floor and concrete walls on one outside length wall and in the rear, rest is drywall.
> 
> 
> Sent from my iPhone using Tapatalk


I think the concrete will tend to keep bass in the building and is likely part of the problem. I think your idea of putting insulation in the ceiling is a good one and more would likely help, plus it's likely less expensive than more panels. If your back wall doesn't have treatment that would be a great place for bass traps, thicker is better. If your GIK first reflection panels aren't at least 4" you could replace them with 4" if you have the space and use what you have for rear side, ceiling, behind the front speakers or other location. If the floor isn't carpeted you could carpet it and use a heavy 8lb carpet pad under the carpet.

Just a few thoughts, others might have a ideas too.

Cheers,


----------



## healthnut

Thanks for your input. Do have carpeting and opted for the thickest pad, I like the idea of more panels to soak up more of the bass waves, would it be practical and/or effective to place bass traps in the ceiling behind the ceiling tiles?


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## darrellh44

*Front Corner Traps with Embedded Speakers*

Hi Guys,

Sorry for yet another corner bass trap post, but I would like to get feedback on my stuffing plan for my floor to ceiling front corner traps. These traps will also be used to 'hide' my L/R main speakers with the grills flush mounted thru the front of the traps. The traps will also be covered in black velvet and will butt up against my projector screen so that the screen is recessed and surrounded by black material.

Here's a diagram of what I'm planning. The speaker is the Danley SM60F, and is shown as the trapezoidal shape shown below the insulation. Its front dimensions are 21"x21".










I definitely want to use the OC703 and Ultratouch since I already have them in hand, but have a couple of questions:
1. Can the fluffy material in the center be the white non-fiberglass batting, or is real fiberglass better?
2. Would it be better to use double thickness on the OC703 and less of the fluffy batting?
3. I have the plastic scrim that GIK used to sell a few years ago for facing the OC703. Can it be glued on?​
Thanks,
Darrell


----------



## dnoonie

healthnut said:


> would it be practical and/or effective to place bass traps in the ceiling behind the ceiling tiles?


If they're above the ceiling tiles you don't need a frame or cover so you could just buy bare insulation and stack it 4 or more inches high:

http://www.gikacoustics.com/product-category/diy-acoustic-panel-bass-traps-supplies/
http://www.acoustimac.com/acoustic-insulation-materials/acoustic-insulation
http://www.acoustimac.com/clr-mnw1280, clearance
http://www.atsacoustics.com/cat--Fiberglass-and-Mineral-Wool-Batts-and-Boards--106.html

Cheers,


----------



## healthnut

dnoonie said:


> If they're above the ceiling tiles you don't need a frame or cover so you could just buy bare insulation and stack it 4 or more inches high:
> 
> http://www.gikacoustics.com/product-category/diy-acoustic-panel-bass-traps-supplies/
> http://www.acoustimac.com/acoustic-insulation-materials/acoustic-insulation
> http://www.acoustimac.com/clr-mnw1280, clearance
> http://www.atsacoustics.com/cat--Fiberglass-and-Mineral-Wool-Batts-and-Boards--106.html
> 
> Cheers,



Thanks, that could work.


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## asarose247

Broadband cloud project and rigid closed cell foam sheets

yes, it poor absorber

How does that relate to being AT?

I need the rigidity for support of layers of Roxul

The pics show the lattice support structure I have bolted together

ALL input welcomed

TY


----------



## darrellh44

Does anyone have comments on the questions at the bottom?




darrellh44 said:


> Hi Guys,
> 
> Sorry for yet another corner bass trap post, but I would like to get feedback on my stuffing plan for my floor to ceiling front corner traps. These traps will also be used to 'hide' my L/R main speakers with the grills flush mounted thru the front of the traps. The traps will also be covered in black velvet and will butt up against my projector screen so that the screen is recessed and surrounded by black material.
> 
> Here's a diagram of what I'm planning. The speaker is the Danley SM60F, and is shown as the trapezoidal shape shown below the insulation. Its front dimensions are 21"x21".
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I definitely want to use the OC703 and Ultratouch since I already have them in hand, but have a couple of questions:
> 1. Can the fluffy material in the center be the white non-fiberglass batting, or is real fiberglass better?
> 2. Would it be better to use double thickness on the OC703 and less of the fluffy batting?
> 3. I have the plastic scrim that GIK used to sell a few years ago for facing the OC703. Can it be glued on?​Thanks,
> Darrell


----------



## BasementBob

darrellh44 said:


> 1. Can the fluffy material in the center be the white non-fiberglass batting, or is real fiberglass better?


Doesn't make much difference. I assume the 'non-fiberglass' is the same ultratouch mentioned here http://www.bobgolds.com/AbsorptionCoefficients.htm 



darrellh44 said:


> 2. Would it be better to use double thickness on the OC703 and less of the fluffy batting?


From an acoustics perspective, if you can keep the fluffy all the way to the top without it settling, it will be fine. If it settles a bit you probably won't notice. The purpose of the additional porous absorption in the back is to level out and extend the absorption frequency range and coefficient a bit. (compare studiotips coroner absorber absorption coefficients vs studiotips superchunks absorber coefficients)
From a physics of construction perspective, you're using the OC703 as a rigid front. From an acoustics perspective, it's better to have the fluffy on the room side, with the more dense against the wall, because the sound has less impedance with the front fluffier layer -- but it's harder to build that without it puffing out and losing the WAF.
I did it once http://bobgolds.com/Absorber/home.htm with fluffy at the front/room side. And after a year it had puffed out the front. Fantastic absorber though -- completely eliminated an imaging problem due to a side wall reflection.



darrellh44 said:


> 3. I have the plastic scrim that GIK used to sell a few years ago for facing the OC703. Can it be glued on?


If this is mostly for aesthetics, a light edge frame glued on, then yes. It needs glue on every bit of it. Consider how little force it takes to drive your fingernails into OC703 and rip out a bit. The glue will hold forever to the fiberglass that it touches, and if there's only a little glue odds of it just ripping out a chunk of fiberglass from the main body go up significantly. If you're trying to support it by this, you're best off surrounding it with a frame. That said I've seen hook type and pad-screw in the middle of a panel rather than the edges that hold for years.


----------



## HoosierFan

The rear of my proposed theater is open to the stairs. I have attached a picture.

I want to do acoustical treatments to the back. I was thinking of a 4"panel in the middle and two corner bass traps. But where would I put the right corner trap? If I put it at the bottom of the steps, it's not in line of sight with the speakers. Should I just put a flat panel where the corner would be if the wall was extended?


----------



## HopefulFred

Line of sight is not relevant for this.


----------



## BllDo

HoosierFan said:


> The rear of my proposed theater is open to the stairs. I have attached a picture.
> 
> I want to do acoustical treatments to the back. I was thinking of a 4"panel in the middle and two corner bass traps. But where would I put the right corner trap? If I put it at the bottom of the steps, it's not in line of sight with the speakers. Should I just put a flat panel where the corner would be if the wall was extended?


Do you need bass traps, or rather, do you need two full corners of bass trapping? How much of an issue are you currently dealing with?


----------



## HoosierFan

I haven't started building yet. I am trying to plan it out. I am not sure what I would need.

I was going to have 2 or 3 2x4 panels on each side of the room, and a 48" x 4" bass trap in each corner and an extra thick panel in the center back.


----------



## dnoonie

HoosierFan said:


> The rear of my proposed theater is open to the stairs. I have attached a picture.
> 
> I want to do acoustical treatments to the back. I was thinking of a 4"panel in the middle and two corner bass traps. *But where would I put the right corner trap?* If I put it at the bottom of the steps, it's not in line of sight with the speakers. Should I just put a flat panel where the corner would be if the wall was extended?


It needs to be in the corner. If the corner is at the bottom of the stairs that's where it should go. Corners get bass build up regardless, that's why it's best to treat them. It would help to put a couple more bass traps on the back wall as well, but treat first reflection points first.

Cheers,


----------



## darrellh44

BasementBob said:


> Doesn't make much difference. I assume the 'non-fiberglass' is the same ultratouch mentioned here http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> From an acoustics perspective, if you can keep the fluffy all the way to the top without it settling, it will be fine. If it settles a bit you probably won't notice. The purpose of the additional porous absorption in the back is to level out and extend the absorption frequency range and coefficient a bit. (compare studiotips coroner absorber absorption coefficients vs studiotips superchunks absorber coefficients)
> From a physics of construction perspective, you're using the OC703 as a rigid front. From an acoustics perspective, it's better to have the fluffy on the room side, with the more dense against the wall, because the sound has less impedance with the front fluffier layer -- but it's harder to build that without it puffing out and losing the WAF.
> I did it once http://bobgolds.com/Absorber/home.htm with fluffy at the front/room side. And after a year it had puffed out the front. Fantastic absorber though -- completely eliminated an imaging problem due to a side wall reflection.
> 
> If this is mostly for aesthetics, a light edge frame glued on, then yes. It needs glue on every bit of it. Consider how little force it takes to drive your fingernails into OC703 and rip out a bit. The glue will hold forever to the fiberglass that it touches, and if there's only a little glue odds of it just ripping out a chunk of fiberglass from the main body go up significantly. If you're trying to support it by this, you're best off surrounding it with a frame. That said I've seen hook type and pad-screw in the middle of a panel rather than the edges that hold for years.


Hi Bob,

Thanks for the reply. For the non-fiberglass filler in the center, I was referring to some other low GFR material other than fiberglass batting. Ultratouch will only be used against the walls. I've read that some other materials might perform better than fiberglass batting or don't settle as much.

I do plan to use a wood frame around the outside of the trap. The vertical members of the frame can be seen in my original diagram at the wall boundaries and in the middle where the angle changes. The outside of the frame will be covered in black velvet for visual reasons. I could use stiff netting and/or the plastic scrim on the inside of the frame to hold the loose fluffy fill instead of using the rigid OC703.

Last night I started playing with the Porous Absorber Calculator from acouticmodeling.com. I setup a model to compare with and without the OC703 outer layer. It predicts using fluffy material on the outer layer instead of the OC703 will perform slightly better above 80 Hz. Below 80 Hz, however, having the OC703 extends the low-frequency absorption quite a bit.


----------



## myfipie

Kamikaze13 said:


> I peeled the black mat face a bit and it's very porous and reminds me of a lot of house wrap, so I assume that would be fine facing outwards? It's just nicer with the black facing out.


mmmm Might be ok.. Does the company have any lab numbers?


----------



## Kamikaze13

myfipie said:


> mmmm Might be ok.. Does the company have any lab numbers?


http://www.imanson.com/modules/technical_brochures/download.php?id=83&t=p


----------



## asarose247

The lurking and reading here was a tremendous guide to produce this

3 clouds, 3' x 4' x 5 1/2"+ thick, 3 1/2 " of 703 topped by layer of Roxul
about 5-6 inches down from the ceiling

wrapped in AT speaker grill cloth 

placed with the aid of the "on ceiling mirror reflective locator " trick

some TV shows have a low level of dialogue, like "Elementary", getting every word from Sherlock a detective story in itself,

watched a few minutes wrt on demand

new levels of clarity 

TY to all fellow AVS' ers for contributing


----------



## Bengineer

First post! Woohoo!

Building in a garage and making it a Media / TV room. Since the walls will be going in from scratch, good chance to get it right.

Speakers will be in wall speakers front left right and centre, rear probably in the ceiling. The main wall is 200m thick concrete filled block, and will have timber frame built inside it.

It isn't a dedicated HT room or a high end set up, but figured I can give it something more than just plasterboard on timber. Room is 4.0m across and 6.0m long, approx.

Few questions on wall treatment;

Main Wall (TV and front speakers)

1. Build the timber frame wall hard against the block, or allow a small gap?
2. Sound insulation? Ply? Then plastboard.

Other walls / ceiling

1. Insulation? Just plasterboard? Ply ?

So much info around, but a lot of it probably overkill for my purposes.


----------



## HiFiGuy1

Looking at doing my front wall behind the screen. Where are we getting Linacoustic or Insul-Shield? I thought it had been mentioned that Lowes or HD was a source, but I checked with both of them, and no dice. Also, is there a specific variety? They seem to be available in a multitude of form factors.


----------



## xxrb1

HiFiGuy1 said:


> Looking at doing my front wall behind the screen. Where are we getting Linacoustic or Insul-Shield? I thought it had been mentioned that Lowes or HD was a source, but I checked with both of them, and no dice. Also, is there a specific variety? They seem to be available in a multitude of form factors.


For Linacoustic and other JM specific products go on JM web site and look for distributors in your area and call them for quotes.
Lowes and HD mostly carry JM fiberglass insulation in batt or roll for classical walls and ceilings insulation, nothing for HVAC duct as far as I know.


----------



## HopefulFred

HiFiGuy1 said:


> Looking at doing my front wall behind the screen. Where are we getting Linacoustic or Insul-Shield? I thought it had been mentioned that Lowes or HD was a source, but I checked with both of them, and no dice. Also, is there a specific variety? They seem to be available in a multitude of form factors.


Since you are near my part of the world, I'll refer you to some of the chatter in my thread about it. http://www.avsforum.com/forum/19-de...2262-once-future-theater-28.html#post23793766

If your view settings are the same as mine, you can scroll up and down through page 28 (where that link should take you) to see some other chatter - and the payoff is on page 29.

J_P_A had a similar experience, and his sources near Auburn may be of use to you. I failed to find easily a link to the relevant posts in his thread.

The short story is that it seems the insulation distributors all think of these products as the same, and they mostly are, IMO.


----------



## HiFiGuy1

HopefulFred said:


> Since you are near my part of the world, I'll refer you to some of the chatter in my thread about it. http://www.avsforum.com/forum/19-de...2262-once-future-theater-28.html#post23793766
> 
> If your view settings are the same as mine, you can scroll up and down through page 28 (where that link should take you) to see some other chatter - and the payoff is on page 29.
> 
> J_P_A had a similar experience, and his sources near Auburn may be of use to you. I failed to find easily a link to the relevant posts in his thread.
> 
> The short story is that it seems the insulation distributors all think of these products as the same, and they mostly are, IMO.


Thanks. I did read part of that thread, and it seems several times people went in being told they had one thing, only to walk out with an "equivalent product" instead. I am nothing if not persistent, so hopefully I can track down what I need. I had someone from J-M contact me directly last week, so I will track that e-mail down and pressure them for some more solid info on availability.


----------



## mtbdudex

Made a poll, since many are subscribed to this thread may have thoughts on doing this.
*Re-start a new "Acoustical Treatments Master Thread"
*


mtbdudex said:


> The current "Acoustical Treatments Master Thread" was started in May-2003, it's gathered "best practices" and so much great info sharing, however some of which are outdated now.
> 
> Therefore, I'm proposing that thread, a great one, be locked and re-named "Acoustical Treatments Master Thread - Archived May-2003 thru March-2016", and a new one with same exact title be created.
> 
> This will be a simple Yes/No poll, and your comments appreciated of course.


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## lmidgitd

I'd say that would be a huge help. If the first few posts could link to the most asked questions or helpful tips I'm sure we'd all be grateful.


----------



## asarose247

That's 36 ft^2 of 5 - 5 1/2" thick combo of 2" 703 overlayed with 3.5" Roxul 
tried to get an even apportionment wrt to the "Scatmos" .6 tops

definitely a major HT upgrade wrt clarity

the hushed effect in silence at the mlp very noticeable,

a most convincing example of the absolute necessity for room treatment,

tho not as exciting as "new toys" . it will make you appreciate how it can all come togtether


----------



## healthnut

I'm taking steps to soundproof my ceiling (hat channel, isolation clips, double 5/8 drywall, Green Glue, etc). Is it likely I'll be able to hear more bass in the theater room with so much less bass leaking out through the ceiling? Thoughts? Opinions?


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## mattowpe

*FSK tape*

Here and there I've seen references to adding strips of FSK or FRK scrim (foil tape) to the surface of the insulation inside the panels at the first reflection point, to add a bit of diffusion of mid to high frequencies instead of having all absorption.

Have many of you tried this?

And can anyone tell me what brand and type of FSK/FRK tape would be recommended?


----------



## HiFiGuy1

Well, so much for persistence! I called an HVAC contractor that I know, and he mentioned a supply house for me to visit. I went there and found a product called ToughGard, which looks as if it would be a good substitute, so I bought a 100' roll, which will just barely cover the front area I need it to cover. I remember someone else getting ToughGard, and hope it will perform well. I am layering it, so there will be two layers from top to bottom, side to side, and 18" from the front wall, which covers the space behind my screen wall.


----------



## csprague

Hello - I was wondering if someone might be able to give me some very general advice regarding my room. I've done quite a bit of reading on the subject of treatments, but still have some more specific questions I'm unsure of.

My listening room is an above ground multi-purpose room. It can be completely closed in if the pocket doors at the entrance are closed, and is a 25.5' long, 19' wide, and has 8' ceilings. The back third or so of the room is dedicated to music - there is a baby grand piano on one side, and a collection of guitars, basses, and amps on the other (see pictures). I think all of the things the room is used for would benefit from treatments.

See the very roughly drawn up layout I did in Excel, attached as a jpeg.

Potential problems: there is a sliding glass door on both sides of the room dead center along the walls. My wife probably wouldn't be keen on my having one of these closed in, so unfortunately, they have to stay. Furthermore, on the left wall, there are a couple of windows, plus one more placed more or less behind the left speaker.

So my questions are this: If I have very limited ability to treat the side walls, where should I focus my efforts? I would be able to treat all corners of the room, the ceiling is still possible, and the back wall is a mixed bag. In the corner where the piano is, I have lots of empty wall space. In the other corner, well my guitars are hung on slatwall hangers, and space is limited. I can put a 2" panel behind the guitars, but should I even bother?

Given these constraints, where should I focus my efforts?

Thanks for any advice!


----------



## the3dwizard

Bass traps in the corners to start. Your floor is probably an issue too if it is hardwood in front of the couch. 

If the image is to scale you can load into here http://amray.andymel.eu/ and map out your first reflections. I drew boxes for the speakers to make it behave a little better. This will give you an idea of where some problems may be. I did this to map out my plan then and latter confirmed with REW analysis and moving a single panel around the room. For example, in my room the back wall is more of an issue than the closed door on the right side. It also shows the second order reflection in the back wall corner nook is an issue too. So I am not doing anything with the door. I put absorption on one corner of the nook and diffusion on the back wall next to it. 

I also did a side view to get and idea of the floor and ceiling issues. It helped me decide on doing a cloud. I moved it to where my Atmos speakers would be so I could see the first reflections for the ceiling speakers too.


----------



## csprague

the3dwizard said:


> Bass traps in the corners to start. Your floor is probably an issue too if it is hardwood in front of the couch.
> 
> If the image is to scale you can load into here http://amray.andymel.eu/ and map out your first reflections.


Awesome site! Thanks for the suggestion. As you can probably see though, there are limited options in the corner where my guitars are hanging. Maybe the guitars themselves will make somewhat effective diffusers, but that's probably just wishful thinking. A 2' wide, 4" thick floor to ceiling bass trap there though is out of the question. Would making a soffet traps for that area be effective? 

And as a general question, how important is it that the panel layout be symmetrical? I've heard conflicting advice here.

Chris


----------



## systemlayers

I have a couple of questions for the experts here. 

1. I have a bit of a difficult back of my room. Am I right in thinking there are 3 (maybe 4) corners that need bass trapping here? I'm thinking of covering the openings with drapes but I'd still need one at Door/Wall, Stairs/wall and the back corner right? I'd probably have to make moveable panels. 


2. I have an almost unlimited supply of Johns Manville Spin Glass. 1 Inch thick, 1.02 density (http://www.jm.com/en/manufacturers-solutions/insulation-solutions/appliance/spin-glas-wh-eq/).
Am I right in guessing that this probably isn't good enough for bass traps? I was hoping it would be since I get it free. On http://www.bobgolds.com/AbsorptionCoefficients.htm the 1" listed is 2.25pcf and only 0.08 efficient at 125hz. I should just go pink fluffy for bass traps?

Edit: I think I will try it out. I saw a few posts saying their spin-glas product was fine as rigid, I'll be doing it about 10 inches thick so I think it will be fairly successful. I'll find out at any rate.


----------



## donktard

Hey guys. I don't have a dedicated room, but I am tryin to incorporate some acoustic treatments in my living room. Anyway, here is the deal. My head in MLP is about 3feet from back wall and maybe feet above there is a slanted ceiling. Since my primary concern was clear and intelligible dialogue, I decided to put some treatments back there and on ceiling above. However, any attempt of treatment dramatically ruined frequency response between 120 and 400 Hz. I have created a couple of huge dips in that area and zero improvement in peaks. Once I have put only a fluffy blanket on a ceiling and I got a massive dip at 280Hz, bigger then anything broadband traps succeded to wreck.  Anyway, I think that created dips are Speaker Boundary Interference Response, but I have no idea why adding absorption just makes them worse? Any clues? Am I treating wrong spots? Do I need more absorption elsewhere? Do I need better absorbers? (adding more to floor/ceiling reflection generally makes things worse).


----------



## sdurani

donktard said:


> I got a massive dip at 280Hz...I think that created dips are Speaker Boundary Interference Response


That's probably the most common frequency for boundary cancellation (woofer roughly 1 foot from wall). Which speaker(s) were you measuring when you saw the dip?


----------



## donktard

sdurani said:


> That's probably the most common frequency for boundary cancellation (woofer roughly 1 foot from wall). Which speaker(s) were you measuring when you saw the dip?


Center channel, since it has the most issues. And yeah, its one foot above the floor. Stacking absorption below/infront of it made things worse


----------



## sdurani

donktard said:


> Center channel, since it has the most issues. And yeah, its one foot above the floor. Stacking absorption below/infront of it made things worse


In that case, can you try a thick absorption panel on the wall behind the centre speaker (just above it) and re-measure?


----------



## donktard

sdurani said:


> In that case, can you try a thick absorption panel on the wall behind the centre speaker (just above it) and re-measure?


I did a lot of measurements yesterday.  Right above and about 1-2 feet behind is a 65" plasma TV on TV stand, and AVR + poweramp are there too. And behind TV there is also about 1-2feet free space before the wall. But I have put 3 pieces of 2'x4'x4" traps right between speaker and TV stand (without covering TV picture ofcourse). In both measurements ceiling above my head was treated too. Purple line is before adding traps behind speaker.
Ignore frequency response after 5khz (its incorrect because of mic calibration issue).


----------



## sdurani

donktard said:


> Right above and about 1-2 feet behind is a 65" plasma TV...


That might be where the reflection is coming from that is causing the cancellation (since you already tried absorbing the floor reflection). Next time you do a measuring session, try putting absorption in front of the TV temporarily just to confirm either way whether it's causing the dip around 280Hz.


----------



## donktard

sdurani said:


> That might be where the reflection is coming from that is causing the cancellation (since you already tried absorbing the floor reflection). Next time you do a measuring session, try putting absorption in front of the TV temporarily just to confirm either way whether it's causing the dip around 280Hz.


Will try tomorrow.

Green line is with no treatments. Purple is with treatments above head. Blue is with treatments above head and on the floor in front of speaker.
In my opinion green one just looks best and if I had no impulse response problems I wouldn't even put panels anywhere. But I still don't understand why would adding panels cause these very specific nulls.


----------



## sdurani

donktard said:


> Will try tomorrow.


Thanx, will be interesting to find out one way or the other.


> I still don't understand why would adding panels cause these very specific nulls.


Reflections can sometimes fill in large dips and make them appear shallower. Absorbing those reflections away can expose the true depth of the dip.


----------



## donktard

sdurani said:


> Reflections can sometimes fill in large dips and make them appear shallower. Absorbing those reflections away can expose the true depth of the dip.


Well, thats not amusing at all.
Most drastic solution I can think of is to wall mount plasma TV. Then I could move center channel up to 5 feet and iirc having speaker right next to back wall would move boundary interference to higher frequencies where it would be easier to treat. I could also move mlp 2-4 feet forward then.


----------



## asarose247

Limp Mass materiel substitution question

"Heavier " vinyl sheet flooring, or 2 thinner pieces lightly glued together, as a free hanging piece maybe 1" or so hanging behind, but not touching the front porous materiel or any rear support, attachment portion of the frame.

likely to be highly non-AT,
AN IDEa from reading ,viewing discussion at gearsluts. 

cost per ft^2 could be quite a bit less than the normal limp mass vinyl, unless locally sourced,

my initial searches priced out to over $2+ ft^2

and the flooring can be sized easily

any input or links, etc. welcomed


----------



## Irv Kelman

*Limp Mass*



asarose247 said:


> Limp Mass materiel substitution question
> 
> "Heavier " vinyl sheet flooring, or 2 thinner pieces lightly glued together, as a free hanging piece maybe 1" or so hanging behind, but not touching the front porous materiel or any rear support, attachment portion of the frame.
> 
> likely to be highly non-AT,
> AN IDEa from reading ,viewing discussion at gearsluts.
> 
> cost per ft^2 could be quite a bit less than the normal limp mass vinyl, unless locally sourced,
> 
> my initial searches priced out to over $2+ ft^2
> 
> and the flooring can be sized easily
> 
> any input or links, etc. welcomed


Unless you can completely seal your room, limp mass affords little benefit.


----------



## asarose247

^ 

Thank you very much


----------



## johnnymacIII

Is there a benifit from going from 4 inch thick Knauf with a 2 inch air gap vs 6 inch Knauf without an air gap? I have about 6 inches of space to use and don't want to buy extra board if the benefits are negligible. Thanks.


----------



## HopefulFred

The difference there is very small. I would not spend the money.


----------



## dakkon

My wife and i are in the process of building a house that will have a dedicated Media room. I'd like to be able to hit the ground running when we get to framing and electrical.. The builder should start setting the forms for the foundation next month.


Does anyone have a link that will explain how to interpret room acoustics outputs and determine what needs to be done to adjust/improve the response of the room. I'm planning on getting Fuzzmeasure as i'm a Mac owner and have read that Room Eq Wizard can be hit and miss on the Mac. However, right now i have no idea how to figure out what needs to be done to a room off of a graph alone. first and second inflection points are straight enough to figure out.. But, i'd like to be able to make the room the best i possibly can within a reasonable budget. 

I'd like to be able to DIY as much of my own room correction as i can with input from forum members.. But, i'd like to be able to read up on the subject before hand. Or, if there is a book i can get off of amazon, i wouldn't be opposed to purchasing a book to read up on the subject.


Thanks for any help.


----------



## sludgeogre

dakkon said:


> My wife and i are in the process of building a house that will have a dedicated Media room. I'd like to be able to hit the ground running when we get to framing and electrical.. The builder should start setting the forms for the foundation next month.
> 
> 
> Does anyone have a link that will explain how to interpret room acoustics outputs and determine what needs to be done to adjust/improve the response of the room. I'm planning on getting Fuzzmeasure as i'm a Mac owner and have read that Room Eq Wizard can be hit and miss on the Mac. However, right now i have no idea how to figure out what needs to be done to a room off of a graph alone. first and second inflection points are straight enough to figure out.. But, i'd like to be able to make the room the best i possibly can within a reasonable budget.
> 
> I'd like to be able to DIY as much of my own room correction as i can with input from forum members.. But, i'd like to be able to read up on the subject before hand. Or, if there is a book i can get off of amazon, i wouldn't be opposed to purchasing a book to read up on the subject.
> 
> 
> Thanks for any help.


I'm also planning on building a house soon and I was going to pick this up:

http://thehometheaterbook.com/practical-home-theater-acoustics/

Also, Acoustimac seems to have the most reasonable pricing and even has a package setup that seems pretty straight forward to put together.

http://www.acoustimac.com/home-theater-room-package-2


----------



## jrogers

sludgeogre said:


> I'm also planning on building a house soon and I was going to pick this up:
> 
> http://thehometheaterbook.com/practical-home-theater-acoustics/
> 
> Also, Acoustimac seems to have the most reasonable pricing and even has a package setup that seems pretty straight forward to put together.
> 
> http://www.acoustimac.com/home-theater-room-package-2


I agree with both of your recommendations. I've been extremely happy with acoustimac quality, price and service. Here are two additional resources I found useful:

http://www.crutchfield.com/S-dCKSWCXNQ3N/learn/learningcenter/home/speakers_roomacoustics.html
http://amray.andymel.eu/

The second allows you to visualize reflections in your room from speaker locations to listening position (see attached example).


----------



## Schneeds

Hello all,

Long time reader, first time poster. I'm in the final stages of completing a dedicated theater and I'm setting up my acoustical treatments. There is one area in particular I'm not quite sure how to treat. The entire theater is a roughly 12x18 basement build, but on the rear wall/back of the theater there are two alcoves. Up against the right hand side wall, there is a half stairwell (6 stairs) going upwards to a lower level (tri level house) with a door at the top of the 6 stairs. The stairwell is of your normal variety width, 37 inches. The second alcove is to the left of the stairwell adjoining it, which is under another half stairwell which leads up from that lower level to the main level. The top two feet of this second alcove moves upward at an angle to the ceiling, running parallel with the stairs that it is directly under. This is also 37 inches wide. The total depth of each alcove is 60 inches. There is a 5 inch thick support wall in between the two alcoves. 

Putting doors in front of each area is not option; they have to remain open. What is the best way to go about treat these sections? I know traditionally you want diffusers on the back wall, and absorption on the side walls, but is this the case with a rear alcove? Or does it even matter that much given it's behind the listening positions?

Thanks!


----------



## erwinfrombelgium

johnnymacIII said:


> Is there a benifit from going from 4 inch thick Knauf with a 2 inch air gap vs 6 inch Knauf without an air gap? I have about 6 inches of space to use and don't want to buy extra board if the benefits are negligible. Thanks.





HopefulFred said:


> The difference there is very small. I would not spend the money.


It's not that simple. Depends which surface sits behind it and what surrounds said surface...


----------



## Blacklightning

healthnut said:


> I'm taking steps to soundproof my ceiling (hat channel, isolation clips, double 5/8 drywall, Green Glue, etc). Is it likely I'll be able to hear more bass in the theater room with so much less bass leaking out through the ceiling? Thoughts? Opinions?
> 
> Sent from my iPhone using Tapatalk


 Yes, the bester your soundproofing the more bass stays in your room. But it just means more peaks and nulls, so more bass problems. I really wish I knew this before I heavily soundproofed my room. I now need to send big $$$ in Bass Traps.


BTW if you just sound proof the ceiling the bass will just travel to the next room and then up. It is best to think about soundproofing like a fish tank. If you just soundproof one wall the water(sound) will just spill everywhere else. So huge waste of money.


----------



## johnnymacIII

erwinfrombelgium said:


> It's not that simple. Depends which surface sits behind it and what surrounds said surface...


I've got drywall. Behind the drywall, blown in insulation, behind that, I have brick. Other than that, nothing is surrounding the drywall. I believe I read that GIK monster bass traps are 4 inch insulation and a 3 inch air gap built in. So that got me thinking that 6 inch insulation must not be cost effective enough to sell.


----------



## erwinfrombelgium

johnnymacIII said:


> I've got drywall. Behind the drywall, blown in insulation, behind that, I have brick. Other than that, nothing is surrounding the drywall. I believe I read that GIK monster bass traps are 4 inch insulation and a 3 inch air gap built in. So that got me thinking that 6 inch insulation must not be cost effective enough to sell.


Ah, I misunderstood! We Europeans know Knauf only as a brand of drywall. For you Americans, it's like Rockwool, correct?
With surrounding items, I meant adjacent walls, ceiling, floor. I presumed you were talking about soundproofing, but you are talking about absorption. Never mind.

Indeed an air gap that's the same as the thickness of the absorption is the optimum cost effective.


----------



## JonasHansen

Hi,

I have a question I hope you can help with. My room is very narrow (~10 feet) and not very long (~15 feet). 

The attachment show the seating/speakers and the reflections for the primary seat. What type of treatments and where would you recommend if I want to broaden the soundstage as much as possible? My speakers have a smooth off-axis response.

My own theory: Reflections from side walls would broaden the soundstage, if I make sure to reflect left speaker on left wall and absorb on right wall and the opposite for the right speaker. Because my room is small and I am placed so close to the side walls, then I am afraid that the reflections will do more harm that good. Therefore I have looked at productrs from Vicoustic which looks like to be the best of both worlds:

WaveWood: http://www.vicoustic.com/product/wavewood
Omega Wood: http://www.vicoustic.com/product/omega-wood

They will reflect and maintain some energy but will reduce the SPL of the reflection.

Input is appreciated!


----------



## erwinfrombelgium

These are only 3 of the 6 first reflections. The other are: front wall, floor and ceiling.

You want acoustic treatments that are as broadband as possible. The items you suggest seem midrange absorbers to me which could be handy if you already have to much high frequency absorption (like if you have room wide carpet or a lot of curtains).


----------



## HopefulFred

I think Jonas's theory sounds about right. The questions that I still need answered are: what other problems should be addressed (which goes to Erwin's remarks about generally needing broadband treatment); what range of frequencies need to be reflected/absorbed and at what total time delay for reflections to achieve effective image broadening.

It might be that simply absorbing the opposite side reflection (in which frequency band?) is enough, but there may be further benefit from delaying the near-surface lateral reflection with effective diffusion (again, in what frequency band?)


----------



## donktard

I got a question regarding first reflection treatments.
Is there any reason for not treating first floor reflection with like a typical 2" or 4" broadband absorber other then a general inconvenience?


----------



## Hoodcom

I'm new to the world of acoustical treatments, so I've been trying to research for quite some time now. I've looked into the materials, foam, fiberglass, and mineralwool and have decided that mineral wool is my best bet. Since our family business directly deals with an insulation provider it's easy to get a hold of the stuff, especially since we actually stock 2" thick, 8 pound density sheets of this stuff. I've went ahead and actually got some 3" ordered and on the way. So I plan to use both 2" and 3" mineral wool for my DIY custom panels. 


However, I'm still struggling with figuring out where to place panels, how to determine what locations are needed, especially with the way my ceiling is in my room, which I've been told helps create the null around 200Hz I'm getting with the LCR. I've been directed to this thread in hopes to find a solution for my needs. I'm also willing to make my own bass traps for the room too.

The room is 11' 10" wide by 22' long. The peak ceiling height is about 7', I've forgotten to write this down. I'll get some exact measurements of ceiling height when I get home. Especially if I need to get more specifics for the way the ceiling is, as you can see here:









More pictures are attached in my thread here: http://www.avsforum.com/forum/29-wh...6196-hoodcom-s-audio-system.html#post23868132

I've got some R.E.W. measurements here: http://www.avsforum.com/forum/155-d...099s-system-mostly-rew-time.html#post39867002 
Which are slightly dated, but still highly relevant at hand for the room null at 200 - 300Hz range. 120Hz on that first graph was from phasing issues with the LCR, which I've corrected. However I can take new measurements anytime. 


I can easily fit 2' x 4' panels on the ceiling angles, and I feel 3" will be the thickest I can go. I'd probably want to stick to 2' thick for the flat upper ceiling. Side walls either thickness works for me. Bass traps I can only really fit on the wall you see here. On my thread I linked for pictures, the back wall I can't really put bass traps on due to the doors. I'm thinking of using white foam tape on the doors to help seal them. The door to the left is my closet, I can keep it closed. The door on the back wall on the right is to the hallway. The door on the side wall to the right of it is the head and air closet, already sealed off. The short door by it, sealed as well, goes to a room that used to be a small attic room. Now finished.

The walls in the house all use blown in insulation that's well packed. I also don't have any objections to having some heavier curtains on the window, I always keep it closed. 


Also, how does one determine first or second reflections? Eitherway, I'm ready to get this room treated and learn.


----------



## sludgeogre

Hoodcom said:


> I'm new to the world of acoustical treatments, so I've been trying to research for quite some time now. I've looked into the materials, foam, fiberglass, and mineralwool and have decided that mineral wool is my best bet. Since our family business directly deals with an insulation provider it's easy to get a hold of the stuff, especially since we actually stock 2" thick, 8 pound density sheets of this stuff. I've went ahead and actually got some 3" ordered and on the way. So I plan to use both 2" and 3" mineral wool for my DIY custom panels.
> 
> 
> However, I'm still struggling with figuring out where to place panels, how to determine what locations are needed, especially with the way my ceiling is in my room, which I've been told helps create the null around 200Hz I'm getting with the LCR. I've been directed to this thread in hopes to find a solution for my needs. I'm also willing to make my own bass traps for the room too.
> 
> The room is 11' 10" wide by 22' long. The peak ceiling height is about 7', I've forgotten to write this down. I'll get some exact measurements of ceiling height when I get home. Especially if I need to get more specifics for the way the ceiling is, as you can see here:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> More pictures are attached in my thread here: http://www.avsforum.com/forum/29-wh...6196-hoodcom-s-audio-system.html#post23868132
> 
> I've got some R.E.W. measurements here: http://www.avsforum.com/forum/155-d...099s-system-mostly-rew-time.html#post39867002
> Which are slightly dated, but still highly relevant at hand for the room null at 200 - 300Hz range. 120Hz on that first graph was from phasing issues with the LCR, which I've corrected. However I can take new measurements anytime.
> 
> 
> I can easily fit 2' x 4' panels on the ceiling angles, and I feel 3" will be the thickest I can go. I'd probably want to stick to 2' thick for the flat upper ceiling. Side walls either thickness works for me. Bass traps I can only really fit on the wall you see here. On my thread I linked for pictures, the back wall I can't really put bass traps on due to the doors. I'm thinking of using white foam tape on the doors to help seal them. The door to the left is my closet, I can keep it closed. The door on the back wall on the right is to the hallway. The door on the side wall to the right of it is the head and air closet, already sealed off. The short door by it, sealed as well, goes to a room that used to be a small attic room. Now finished.
> 
> The walls in the house all use blown in insulation that's well packed. I also don't have any objections to having some heavier curtains on the window, I always keep it closed.
> 
> 
> Also, how does one determine first or second reflections? Eitherway, I'm ready to get this room treated and learn.


This room looks very similar to yours, so I would probably model yours after it.

http://www.acoustimac.com/akc/cat/Customer-Photos/post/Home-Theater-Acoustics-Neilson-Eznack

As far as determining where first reflections are, the easiest way is to have one person sitting in the main listening position while another person runs a mirror along the side wall, right against the wall, and when you can see the speaker drivers in the center of the mirror, that's where your reflection points are.


----------



## bpassman

*Timberwall Peel & Stick as a diffusing material?*

Wow, this thread has a lot of pages and years of data to go through! I think I get the fundamentals, but will need more time and studying to truly understand the art/science behind home theater acoustics and the different types of materials. While wandering through Lowes I noticed a new product and wanted to share it and also get thoughts on it as a potential lower 1/3 material. It would add some mass, maybe the peel/stick tape does something (doubtful), and the planks are different heights...which leads me think it might provide some diffusion properties.

Timberwall - Peel & Stick wood wall panels

Vendor site: http://timberwall.us/
Lowes Info: http://www.lowes.com/pd_758847-105-758847_0__?productId=1000014170


----------



## Hoodcom

sludgeogre said:


> This room looks very similar to yours, so I would probably model yours after it.
> 
> http://www.acoustimac.com/akc/cat/Customer-Photos/post/Home-Theater-Acoustics-Neilson-Eznack
> 
> As far as determining where first reflections are, the easiest way is to have one person sitting in the main listening position while another person runs a mirror along the side wall, right against the wall, and when you can see the speaker drivers in the center of the mirror, that's where your reflection points are.


Wow, thank you! That room is quite similar, looks to be taller, deeper, and wider but much the same concept, regarding the actual shape of the room.


So ideally, I'd want to use the mirror method to identify the reflection points of the tweeters, and ensure the panel is large enough to help prevent reflections for the entire speaker? (Especially the woofers, where the 200Hz null is of concern?)


From my understanding, up front, there will be at least two panels per 'wall' for the first reflections? So that one will target the nearest speaker, while the one after it targets the furthest? 


And as for bass traps go, the idea is they are needed most where the bass is heaviest in a room, such as corners? In my space, the bass is heaviest at the back wall, and especially where there's the main bedroom door where it does a bit deeper. Is there much I can do for this area where the door is? I can put some panels there too, and even on the door if it'd help. Like 3" of mineral wool panel on the main bedroom door. Or possibly 2" on it and the other door to the heat and air closet door next to it. And another 2" on the small wall with the light switch right by the door. Then some foam corner pieces up those corners if that'll help any at all.


----------



## JonasHansen

erwinfrombelgium said:


> These are only 3 of the 6 first reflections. The other are: front wall, floor and ceiling.
> 
> You want acoustic treatments that are as broadband as possible. The items you suggest seem midrange absorbers to me which could be handy if you already have to much high frequency absorption (like if you have room wide carpet or a lot of curtains).


Yes, you are right - I am only focusing on the side-wall reflections as this was my theory about how to improve soundstage width. (I wrote the software myself which calculated the reflections, so I skipped the other walls to save time ).

Right now I have broadband absorbers on all reflection points as you recommend, but my soundstage is not very wide. That is why I though about reflecting some of the side wall energy.


----------



## sdurani

JonasHansen said:


> Right now I have broadband absorbers on all reflection points as you recommend, but my soundstage is not very wide. That is why I though about reflecting some of the side wall energy.


In order to widen the soundstage, try removing the absorbers for reflections from the nearby speakers (while continuing to absorb reflections from the speaker on the opposite side).


----------



## sludgeogre

Hoodcom said:


> Wow, thank you! That room is quite similar, looks to be taller, deeper, and wider but much the same concept, regarding the actual shape of the room.
> 
> So ideally, I'd want to use the mirror method to identify the reflection points of the tweeters, and ensure the panel is large enough to help prevent reflections for the entire speaker? (Especially the woofers, where the 200Hz null is of concern?)


I don't know about the width, but remember that the width of the sound wave is going to be equal to the wavelength, not the width of the speaker. The width, in my mind, should actually be close to the width of your body, as you want to prevent reflections to your direction, but not prevent all reflections, as this would overly dampen the room. I think the panel should also be tall enough to cover any position you might sit in.



Hoodcom said:


> From my understanding, up front, there will be at least two panels per 'wall' for the first reflections? So that one will target the nearest speaker, while the one after it targets the furthest?


From my understanding so far, that is correct. One panel is for the left speaker, and the other is for the right. The repeating panels are to help out other listening positions and even out the overall room response.



Hoodcom said:


> And as for bass traps go, the idea is they are needed most where the bass is heaviest in a room, such as corners? In my space, the bass is heaviest at the back wall, and especially where there's the main bedroom door where it does a bit deeper. Is there much I can do for this area where the door is? I can put some panels there too, and even on the door if it'd help. Like 3" of mineral wool panel on the main bedroom door. Or possibly 2" on it and the other door to the heat and air closet door next to it. And another 2" on the small wall with the light switch right by the door. Then some foam corner pieces up those corners if that'll help any at all.


My knowledge in bass trapping is quite limited. From what I understand, bass "accumulates" in corners because of the nature of the long wavelengths/low frequency. The bass trap is designed to absorb that to even out the response. I think you should mainly focus on the corners. You need at least 4" of material to even start attenuating low frequencies, all of the 2" and 3" panels I've seen don't really start to do anything until 100 Hz, and in fact most aren't even rated at all below that, so I don't think that any amount of insulation below 4" on the door is going to do anything for bass response. If you want the door to better seal sound from the room, the best thing would be to change to a solid core door if it is not one already.

You should contact Acoustimac or GIK or one of those companies and see what they recommend as I'm not really that knowledgeable on these matters, I just have a cursory understanding of the physics involved, but I could be off in any number of ways.


----------



## SherazNJ

I'm in the middle of setting up my room. Before, room was open from left side behind MLP. Now its completely closed. So now I'm also planning to treat the room acoustically. I have a 7.2.4 system. One sub is in front and one in back.
To start with, I have front wall covered with 1" LinAcoustics (pic below) and also first reflection on walls and ceilings. Room also has a soffit and I believe should be covered? What should I be using to cover it? Should I use 1" Linacoustic or 2" 703 Ownen? Posting the pics below. So following are the questions

1 - What Should I cover Soffit with?
2 - Side/Ceiling walls are only covered with panels for first reflection. Should I bother covering the rest with 1" Linacoustic or 2" 703 Ownen?
3 - Back wall as of now is not treated at all besides one corner half covered with 8" Rockwool. 

Any advice is appreciated.
Thx

*Room Front Wall*









*Side wall*









*Back wall corner (Soffit is visible here and it goes all across the side wall)*


----------



## donktard

sludgeogre said:


> This room looks very similar to yours, so I would probably model yours after it.
> 
> http://www.acoustimac.com/akc/cat/Customer-Photos/post/Home-Theater-Acoustics-Neilson-Eznack
> 
> As far as determining where first reflections are, the easiest way is to have one person sitting in the main listening position while another person runs a mirror along the side wall, right against the wall, and when you can see the speaker drivers in the center of the mirror, that's where your reflection points are.


I might be wrong but those acoustic panels look like they are positioned for symmetry and not for effectiveness.


----------



## sludgeogre

donktard said:


> I might be wrong but those acoustic panels look like they are positioned for symmetry and not for effectiveness.


It does indeed look like that. That would probably be the one thing I would change.


----------



## nandkisham

*2"OC 703 or 2layerof 1 inch linacoustic*

acoustic experts...

what is the general recommendation? speakers will be towers behind the AT screen

room - 13 x 22

Also, is there a rule of thumb for kind of material for ceiling / sidewalls top and bottom treatment

Any guidance?

Regards,


----------



## nandkisham

*2"OC 703 or 2layer of 1 inch linacoustic*

acoustic experts...

what is the general recommendation? speakers will be towers behind the AT screen

room - 13 x 22

Also, is there a rule of thumb for kind of material for ceiling / sidewalls top and bottom treatment

Any guidance?

Regards,


----------



## johnnymacIII

nandkisham said:


> acoustic experts...
> 
> what is the general recommendation? speakers will be towers behind the AT screen
> 
> room - 13 x 22
> 
> Also, is there a rule of thumb for kind of material for ceiling / sidewalls top and bottom treatment
> 
> Any guidance?
> 
> Regards,


I'm not an acoustical expert by any means. This is just what I've learned over the course of my journey into home theater.

You are going to need:
a measurement mic and Room EQ wizard for this method. 
Traps from GIK acoustics. 
Or, If going the DIY route: Knauf 3lb insulation or Owens Corning 703 insulation. 1x1 pine boards (for building the frames). Guilford of Maine cloth. Don't skimp on the cloth. If your cloth isn't acoustically transparent this is all for nothing. 

Lay corner traps. You can do this by either mounting 4 inch thick by 2 feet wide by 4 feet tall panels stacked on top of each other or to eek out a bit more low frequency trapping, stuff the entire corner with Knauf or 703 and cover with a frame and GoM cloth. 

Add a thick carpet/rug between you and your front soundstage.

Place some Monster bass traps or DIY 4 inch thick with 2 inch air gap behind any LCRs if they are moved away from the front wall.

Now run REW, read the t60 measurement, and lay the rest of your acoustical treatment in steps. The goal is to have an even decay time at least from 250 Hz to 4KHz in the .2 - .5 second range. Let those measurements dictate what you lay from hear on out. 

So let's say now you want to focus on your side wall 1st reflections. Sit at your listening position. Have someone walk around the room with a mirror. When you see the speaker in the mirror mark with painters tape.

Take a measurement. If both your higher frequencies (500 hz and above) and lower frequencies (500 hz and below) need to decay faster you will lay 4 inch absorption. If your lower frequencies are already decaying fast enough, but your higher frequencies are still out of control then lay some 2 inch absorption. If your lower frequencies aren't decaying fast enough; but your higher frequencies are good, then lay a hybrid absorber/diffuser that will absorb and diffuse at the frequency you need them to. If you have even decay times somewhere between .2 - .5 seconds, but you still need to treat the first reflection, then use diffusion.

Next, treat your rear wall and ceiling in the same manner. Keep in mind that if you have more than one row or your seats or your seats are spread wide appart you may need to go back and do the same procedure for those seats as well. 

Again, keep in mind that there are many different strategies to treat rooms. This is what I've found sounds good with HT and multichannel audio. Some acousticians recommend simply covering a certain % of your wall with absorption and a certain percentage with diffusion. Others say don't treat first reflections. Others say treat all first reflection points with absorption. So, YMMV with any of these methods.


----------



## Hoodcom

donktard said:


> I might be wrong but those acoustic panels look like they are positioned for symmetry and not for effectiveness.


I was wondering about that as well.

My purposes will definitely be needed for effectiveness. 



Also, does anyone have any ideas what I can do to try panels in places to make sure it will work properly there? Even after a mirror technique. I want to only have to put any anchors in the sheetrock only once.


----------



## donktard

Hoodcom said:


> I was wondering about that as well.
> 
> My purposes will definitely be needed for effectiveness.
> 
> 
> 
> Also, does anyone have any ideas what I can do to try panels in places to make sure it will work properly there? Even after a mirror technique. I want to only have to put any anchors in the sheetrock only once.


You want to test their effectivenes? Well you could make measurements with Room EQ Wizard (REW). You have a dedicated thread on Audio Theory, Setup and Chat.


----------



## Hoodcom

donktard said:


> You want to test their effectivenes? Well you could make measurements with Room EQ Wizard (REW). You have a dedicated thread on Audio Theory, Setup and Chat.


Well, maybe I worded it wrong, but what I meant was more on me wanting to make sure I pick the right spots before I hang them up officially. 
Mostly responded to what you said about the symmetry vs effectiveness in the link that had pictures to the room similar to mine.

I just didn't want to have to move them and put more holes in the sheet rock is all.


----------



## dnoonie

sludgeogre said:


> This room looks very similar to yours, so I would probably model yours after it.
> 
> http://www.acoustimac.com/akc/cat/Customer-Photos/post/Home-Theater-Acoustics-Neilson-Eznack
> 
> As far as determining where first reflections are, the easiest way is to have one person sitting in the main listening position while another person runs a mirror along the side wall, right against the wall, and when you can see the speaker drivers in the center of the mirror, that's where your reflection points are.


The Pic in the above acoustimac link seems to indicate a general room treatment with an aesthetic appeal rather than a theater room specific to speaker placement type of treatment. The room looks challenging to treat given that transition from vertical/90 degree to a ~135 degree angle happens at about ear level when seated. Both vertical and 135 degree "walls" will need treatment, you'll need French Cleats/z-clips on both top and bottom (edit: for the "135 degree walls") so you might need to order extras, acoustimac gives you a few extras when you order a room packages so you might be covered.

If you have the ability to treat exact reflection points you should rather than go with a general room treatment like the acousticmac picture indicates. Check out this video on reflection points, http://www.gikacoustics.com/video-early-first-reflection-points/*.*

As a side note if you do purchase from acoustimac you might want to consider matching to a GIK acoustics available fabric (they both have *Guilford*), I think GIK has better bass traps at a better price than acoustimac, although acoutimac has great deals on treatment packages. I wish I'd have matched fabrics since I'd like to use some GIK bass traps and I like the concept of their Evolution PloyFusor.

I'd like to replace rear ceiling corner absorbers with Evolution PolyFusors back-filled with extra insulation but I'm at a loss as to how to match fabrics....actually not now that I type this...since I can likely get samples from GIK.

Cheers,


----------



## Witchboard

donktard said:


> I might be wrong but those acoustic panels look like they are positioned for symmetry and not for effectiveness.


Sorry, I'm new to researching room treatments and will admit I know nothing, but if your speaker placements are symmetrical, wouldn't the treatments be as well?


----------



## donktard

Witchboard said:


> Sorry, I'm new to researching room treatments and will admit I know nothing, but if your speaker placements are symmetrical, wouldn't the treatments be as well?


Well, yes, but not necessarily so evenly spaced. The way I see it person that put them just made sure there is equal distance between each panel, or at least so it looks on pictures.
What definitely looks wrong are panels BEHIND front speakers and last panels at back of the room, those absorb nothing important.
Generally, you want to treat first reflections, SBIR (if necessary/possible), put traps in corners and then if you want to deaden the room further I suppose you could treat secondary reflections, etc, etc.


----------



## Witchboard

donktard said:


> Well, yes, but not necessarily so evenly spaced. The way I see it person that put them just made sure there is equal distance between each panel, or at least so it looks on pictures.
> What definitely looks wrong are panels BEHIND front speakers and last panels at back of the room, those absorb nothing important.
> Generally, you want to treat first reflections, SBIR (if necessary/possible), put traps in corners and then if you want to deaden the room further I suppose you could treat secondary reflections, etc, etc.


Ah, I understand now. You're meaning the symmetry of the panels beyond the initial first reflection panel. Got it.


----------



## jedi1982

I have a question (out of the blue) on when to use Kraft paper when building Superchunk corner bass traps and when not to. From what I'm reading it seems like it might be a good idea to use kraft paper on the front of the bass traps in the rear of the room to help reflect some of the mid-high freqs but best not to cover the front of the room corner traps as you want that wall dead. Is this on the right track? Thx


----------



## jedimastergrant

Looking for material to treat ceiling for Atmos install. Not treated currently. 

I have approx 1/3 of all walls treated with 705. 

Then 1'' of select sound black with a layer of 3 mill poly followed by another layer of 1'' select sound black on the front wall. 

My riser is a continuous cavity bass trap. 

I am looking for material locally and I have found some 1'' Johns Manville IS 600. It has slightly different absorption coefficients compared to the 705 I used previously. Does this matter? Can I just layer it to 2'' and use it on the ceiling? Is there a better option for ceiling atmos treatment?

Also considering doing the 242 panels from gik instead of diy depending on cost difference and what material I need to be using. Do they use 703?


----------



## Mashie Saldana

Are basstraps needed if 4 subwoofers are used (one in each corner)?


----------



## HopefulFred

Mashie Saldana said:


> Are basstraps needed if 4 subwoofers are used (one in each corner)?


Bass traps are always good. so, yes.


----------



## jedimastergrant

jedimastergrant said:


> Looking for material to treat ceiling for Atmos install. Not treated currently.
> 
> I have approx 1/3 of all walls treated with 705.
> 
> Then 1'' of select sound black with a layer of 3 mill poly followed by another layer of 1'' select sound black on the front wall.
> 
> My riser is a continuous cavity bass trap.
> 
> I am looking for material locally and I have found some 1'' Johns Manville IS 600. It has slightly different absorption coefficients compared to the 705 I used previously. Does this matter? Can I just layer it to 2'' and use it on the ceiling? Is there a better option for ceiling atmos treatment?
> 
> Also considering doing the 242 panels from gik instead of diy depending on cost difference and what material I need to be using. Do they use 703?


I can source the John mansville IS 600 for cheap. Can anyone tell me if the small differences in absorption coefficients between it and the OC 705 are significant in any way? Use would be ceiling atmos treatment. Thanks


----------



## JonasHansen

I could need some input on how my bass behaves in my room.

I have three subwoofers behing my screen and one subwoofer behind the listening position. The measurements look basically the same whether or not the "back sub" is active or not.

My problem is, that 50-60hz is really bad everywhere in the room. I have tried to measure everywhere in the room and listed the results:










As you can see, the response in 50-60 is really bad at all listening positions. Because the response is almost identical for all measurements made in the same length of the room, I dont see that the 55hz issue is a room mode. If it was, it would change as I moved around in the room.

I have tried moving a subwoofer around the room, and the issue is there no matter where I place the subwoofer.

Do you have any ideas what is causing this?

Room dimension and calculated modes are given here:


----------



## sdurani

JonasHansen said:


> I have three subwoofers behing my screen and one subwoofer behind the listening position.


Where behind the screen are the three subwoofers in relation to room width?


> I dont see that the 55hz issue is a room mode. If it was, it would change as I moved around in the room.


The peak is not changing frequency but appears to be changing amplitude, getting louder as you get closer to a room boundary (back wall).


----------



## JonasHansen

sdurani said:


> Where behind the screen are the three subwoofers in relation to room width? The peak is not changing frequency but appears to be changing amplitude, getting louder as you get closer to a room boundary (back wall).


The subs are placed left, center, right. See attachment.
But as I mentioned, the response basically looks the same if I measure with one sub or all subwoofers.

The peak in the response makes perfect sense and that follows the theory I know about room modes. But the big dip at 50-55hz is very weird to me. Exists in all locations and does not change much.


----------



## robin luo

Dennis Erskine said:


> I would not use the 2" material...it will very likely be too absorptive.
> 
> 
> The fill out is polyester batting. Don't use styrofoam.


----------



## jedi1982

Ok so as I'm reading this thread from the beginning (currently on pg 24), there are many different ideas of materials and thicknesses that seem to go together and often collide. What I'm needing help determining is what would be ideal for acoustic paneling walls in the home theater I'm planning on building?

-1" Linacoustic directly onto the walls
-1" Linacoustic spaced 1" away from the walls

or

-1" OC 703 directly onto the walls
-1" OC 703 spaced 1" away from the walls

or

-Other recommendations??!


----------



## erwinfrombelgium

JonasHansen said:


> The subs are placed left, center, right. See attachment.
> But as I mentioned, the response basically looks the same if I measure with one sub or all subwoofers.
> 
> The peak in the response makes perfect sense and that follows the theory I know about room modes. But the big dip at 50-55hz is very weird to me. Exists in all locations and does not change much.


Just guessing: maybe it's the materials of the combined walls, floor and ceiling that's causing this?? If so, a tuned bass absorber might help?


----------



## erwinfrombelgium

jedi1982 said:


> Ok so as I'm reading this thread from the beginning (currently on pg 24), there are many different ideas of materials and thicknesses that seem to go together and often collide. What I'm needing help determining is what would be ideal for acoustic paneling walls in the home theater I'm planning on building?
> 
> -Other recommendations??!


None of the above. There's no substitute for inches! One inch is only a treble muter... 2" is the very minimum. Me, I applied 5" of dense rockwool with 3" plenum on my ceiling. On the sides, I made large diffusion (you need a wide room to do that). The space is still not finished, but I tested with a pair of outdoor speakers, and on first hearing, it sounds fantastic.

Happy reading as this is fascinating stuff!


----------



## mushroommunk

erwinfrombelgium said:


> None of the above. There's no substitute for inches! One inch is only a treble muter... 2" is the very minimum. Me, I applied 5" of dense rockwool with 3" plenum on my ceiling. On the sides, I made large diffusion (you need a wide room to do that). The space is still not finished, but I tested with a pair of outdoor speakers, and on first hearing, it sounds fantastic.
> 
> Happy reading as this is fascinating stuff!


Agreed, as you read further along, or dig into other threads (such as the one proposing a replacement for this one), you'll find that all the old recommendations kind of became outdated and everyone advises thicker now. At least that's my understanding.


----------



## jedi1982

mushroommunk said:


> Agreed, as you read further along, or dig into other threads (such as the one proposing a replacement for this one), you'll find that all the old recommendations kind of became outdated and everyone advises thicker now. At least that's my understanding.


Ok cool and thanks. Will plan for at least 2"


----------



## Hoodcom

dnoonie said:


> The Pic in the above acoustimac link seems to indicate a general room treatment with an aesthetic appeal rather than a theater room specific to speaker placement type of treatment. The room looks challenging to treat given that transition from vertical/90 degree to a ~135 degree angle happens at about ear level when seated. Both vertical and 135 degree "walls" will need treatment, you'll need French Cleats/z-clips on both top and bottom (edit: for the "135 degree walls") so you might need to order extras, acoustimac gives you a few extras when you order a room packages so you might be covered.
> 
> If you have the ability to treat exact reflection points you should rather than go with a general room treatment like the acousticmac picture indicates. Check out this video on reflection points, http://www.gikacoustics.com/video-early-first-reflection-points/*.*
> 
> As a side note if you do purchase from acoustimac you might want to consider matching to a GIK acoustics available fabric (they both have *Guilford*), I think GIK has better bass traps at a better price than acoustimac, although acoutimac has great deals on treatment packages. I wish I'd have matched fabrics since I'd like to use some GIK bass traps and I like the concept of their Evolution PloyFusor.
> 
> I'd like to replace rear ceiling corner absorbers with Evolution PolyFusors back-filled with extra insulation but I'm at a loss as to how to match fabrics....actually not now that I type this...since I can likely get samples from GIK.
> 
> Cheers,


For the room treatments, I plan to build my own. Alright, I just need to get a mirror then to do the mirror trick. I don't know the actual angles of the ceiling but that shouldn't be too hard to figure out.


Recent measurements at multiple placements:
http://www.avsforum.com/forum/155-d...099s-system-mostly-rew-time.html#post44505785

Then up to 20kHz on this for the front left and right at main position:


----------



## MinnesotaGreg

*Latest on baffle walls and AT screen to LCR distance?*

After reading many hours I'm still going in circles on this topic  and if anyone can answer or know of reference articles I would appreciate it greatly. I'm looking for information on the following items:


1. Ideal distance between AT screen and front of speakers (DIY 1099 spkrs most likely). I've read materials on this topic ranging from 1" to 12" and trying to learn what is ideal rather than marketing material selling gear for an application that might be space constrained. 


2. Ideal depth of area holding the LCR speakers behind the baffle wall if no space constraints. Answer to question one above would assist answering this question. 


3. Will it be acceptable to not insulate around each LCR in baffle wall but rather the entire wall behind all the LCR speakers with blue jean insulation?


4. Planning on using sound barrier as shown in pic for front of baffle wall.


I'm struggling with how to proceed at this point of my build. I think I may have to simply starting building and be willing to completely redo if sound doesn't work out.


----------



## pgwalsh

I have an 18x19 room and with the speakers along the long side. Suggestions on diffuser and absorption? Should I start a separate thread?


----------



## jedimastergrant

robin luo said:


>


robin,

Was this quote for me or someone else? Was Dennis talking about ceiling treatment for atmos in that quote? I know that some of the Erskine atmos designs can use reflection so that will be different from my direct radiators pointed at the listeners. 

I would guess that 1'' will take too much treble away? Maybe 2'' is more even absorption across the frequencies? Hard to say.


----------



## JDontee

I've looked on the forums for an answer and I can't seem to find anyone who has tried this. I have low ceilings in my theater, so hanging acoustic treatments are a challenge for my first reflection point. Has anyone tried in-wall or in-ceiling acoustic treatments? I had the idea of cutting out the drywall at my first reflection point on my ceiling, filling that space with rockwool, then placing fabric over the hole and trim around the edges. I would place some wire or strips of wood to support the rockwool as it was hanging if needed. The floor above would be the backer, and it would be about 10 inches of rockwool to absorb the sound. I'm not worried about compromising a sound envelope. Has anyone tried this or does anyone think it would work?


----------



## Mashie Saldana

JDontee said:


> I've looked on the forums for an answer and I can't seem to find anyone who has tried this. I have low ceilings in my theater, so hanging acoustic treatments are a challenge for my first reflection point. Has anyone tried in-wall or in-ceiling acoustic treatments? I had the idea of cutting out the drywall at my first reflection point on my ceiling, filling that space with rockwool, then placing fabric over the hole and trim around the edges. I would place some wire or strips of wood to support the rockwool as it was hanging if needed. The floor above would be the backer, and it would be about 10 inches of rockwool to absorb the sound. I'm not worried about compromising a sound envelope. Has anyone tried this or does anyone think it would work?


It should work fine, the trick is to get a frame with fabric attached in a suitable way.


----------



## JDontee

Mashie Saldana said:


> It should work fine, the trick is to get a frame with fabric attached in a suitable way.


Thanks for the reply. I have some unfinished basement and I think I'll do a test run down there to see how it could all work out, and make sure it doesn't cause any sagging. I just wonder how much it will settle over time.


----------



## HarpNinja

I am looking at doing acoustic panels. My current set up is 5.1.2, and I am using Audyssey XT. The sectional is 13.5' from the screen and I am eventually going to go 5.1.4.

While I think I have a basic handle on how to find placement with a mirror, I have specific questions about the right side (as you face the screen) of the living room as it is an odd shape. 

1. How do the stairs on the right side impact reflections (there is no door upstairs)? 

2. Should I treat the side wall at the bottom of the stairs? 

3. I am guessing I will want a panel next to each side surround or there abouts? Is that less of an issue because they are behind me?

Should I treat the back wall too? Behind the couch is all toys for now. Eventually it will be a bar area. 

I marked their rough placement on the attached pic. My 120" screen is centered with the sectional and NOT with the room. The screen edge is about 4ft from the left wall. All the speakers are within Dolby spec. The top middles are right at 100 degrees and almost like top rears. The side surrounds are at about 100 degrees too. 

I am thinking of trying to do DIY movie poster panels on the left side. Might go plain color if I need some around the stair landing. If I need something by the side surrounds, I might do art work or plain color.

Thanks!


----------



## Mashie Saldana

JDontee said:


> Thanks for the reply. I have some unfinished basement and I think I'll do a test run down there to see how it could all work out, and make sure it doesn't cause any sagging. I just wonder how much it will settle over time.


if you are going for standard fluffy insulation you will need something like chicken mesh to hold it up. With rigit boards and not too large sections you migth be able to get away with just the wooden frames and fabric. I will go for the chicken mesh + fabric to hold up rigid board myself.


----------



## JDontee

Mashie Saldana said:


> if you are going for standard fluffy insulation you will need something like chicken mesh to hold it up. With rigit boards and not too large sections you migth be able to get away with just the wooden frames and fabric. I will go for the chicken mesh + fabric to hold up rigid board myself.


I was thinking the same thing. Fabric, batting, chicken wire, roxul and trim on the ceiling edges.


----------



## HopefulFred

JDontee said:


> I was thinking the same thing. Fabric, batting, chicken wire, roxul and trim on the ceiling edges.


I _think_ the reason people don't do this is because wouldn't pass a building inspection. The drywall is the firebreak, if I understand correctly.


----------



## JDontee

HopefulFred said:


> I _think_ the reason people don't do this is because wouldn't pass a building inspection. The drywall is the firebreak, if I understand correctly.


So if I place drywall inside the joist on all the surfaces, would that work?


----------



## HopefulFred

Again, if I understand the code properly, the living space needs to be separated from the wall/floor cavity. So, I _think_ there would need to be a box or something so that the space is sealed. Don't take my word for it though. Ask someone who deals in building codes regularly.


----------



## dnoonie

HarpNinja said:


> I am looking at doing acoustic panels. My current set up is 5.1.2, and I am using Audyssey XT. The sectional is 13.5' from the screen and I am eventually going to go 5.1.4.
> 
> While I think I have a basic handle on how to find placement with a mirror, I have specific questions about the right side (as you face the screen) of the living room as it is an odd shape.
> 
> 1. How do the stairs on the right side impact reflections (there is no door upstairs)?
> 
> 2. Should I treat the side wall at the bottom of the stairs?
> 
> 3. I am guessing I will want a panel next to each side surround or there abouts? Is that less of an issue because they are behind me?
> 
> Should I treat the back wall too? Behind the couch is all toys for now. Eventually it will be a bar area.
> 
> I marked their rough placement on the attached pic. My 120" screen is centered with the sectional and NOT with the room. The screen edge is about 4ft from the left wall. All the speakers are within Dolby spec. The top middles are right at 100 degrees and almost like top rears. The side surrounds are at about 100 degrees too.
> 
> I am thinking of trying to do DIY movie poster panels on the left side. Might go plain color if I need some around the stair landing. If I need something by the side surrounds, I might do art work or plain color.
> 
> Thanks!


Hi,

1. Reflections from the stairwell should be late enough and weak enough that they shouldn't impact imaging although they may be annoying enough that you might want to treat around or in the stairwell to stop echos. You will get late echo's that may or may not be loud enough to bother you. Having no door on the other end will tend to let sound (especially bass) leak into the other space, a good thing for your listening space but a bad thing for the adjoining space.

2. Yes you'll want to treat the first and second reflection points on the wall by the stair. Here's a link to a video on finding reflection points, http://www.gikacoustics.com/video-early-first-reflection-points/. Don't forget the ceiling and floor.

3. Treat surround speaker sound like you would your mains. Use a mirror like in the video link above for surrounds too.

Most acoustic panel sellers will print your image on acoustic fabric for you.
Some resources
http://www.gikacoustics.com/
http://www.acoustimac.com/
http://www.atsacoustics.com/
http://www.acousticsfirst.com/
http://realtraps.com/index.htm
http://www.primacoustic.com/

Cheers,


----------



## asoofi1

Molon_Labe said:


> I posted this in the Atmos section and figured I would post here too in hopes of receiving the most feedback.
> 
> For those who have Atmos/DTS:X and treated ceilings, what did you use? I plan to use the typical absorption panels between the mains and front Atmos speakers to handle first reflections, but I am thinking of using diffusion for the section in between the ceiling speakers. I am torn between two products. I really like the DC2 the most because it just "looks awesome" on the ceiling. However, the primary goal is the treatment so I won't go with the "cooler" of the two. I could use any feedback from those who have gone down this road before. Here are the two models I have narrowed my choices to. I am also open to using absorption in the middle instead if that is the optimal choice. I just figured diffusion would open up the Atmos/DTS:X sounds stage above the two rows of seating, but I am by no means qualified to make that assumption. Ceiling is 9ft. I know diffusion is typically only recommend for 10+ feet ceilings, but I wasn't sure if Atmos has impacted that standard design principle or not.
> 
> Vicoustic Multifuser DC2
> 
> 
> 
> GIK GridFusor
> 
> 
> 
> Thoughts? Pro/Cons to either or?


 @BrolicBeast did a really nice job with his absorption panels and overhead speakers...he basically made cloud panels with the speakers baffled in the panel...hides the speakers and absorbs 

http://www.avsforum.com/showthread.php?t=1498937


----------



## dnoonie

Molon_Labe said:


> I posted this in the Atmos section and figured I would post here too in hopes of receiving the most feedback.
> 
> For those who have Atmos/DTS:X and treated ceilings, what did you use? I plan to use the typical absorption panels between the mains and front Atmos speakers to handle first reflections, but I am thinking of using diffusion for the section in between the ceiling speakers. I am torn between two products. I really like the DC2 the most because it just "looks awesome" on the ceiling. However, the primary goal is the treatment so I won't go with the "cooler" of the two. I could use any feedback from those who have gone down this road before. Here are the two models I have narrowed my choices to. I am also open to using absorption in the middle instead if that is the optimal choice. I just figured diffusion would open up the Atmos/DTS:X sounds stage above the two rows of seating, but I am by no means qualified to make that assumption. Ceiling is 9ft. I know diffusion is typically only recommend for 10+ feet ceilings, but I wasn't sure if Atmos has impacted that standard design principle or not.
> 
> Vicoustic Multifuser DC2
> 
> 
> 
> GIK GridFusor
> 
> 
> 
> Thoughts? Pro/Cons to either or?


 The GIK may have a slight performance advantage being a little thicker. It looks like the Vicoustic might be $125 for a box of 6? http://store.acousticfrontiers.com/Vicoustic-Multifuser-DC2.html, it's hard to tell, it saw 6 units per box in the .pdf. I'd get the one that's the least expensive, one is about half the price as the other.

Please post back with what you find.

Cheers,


----------



## Molon_Labe

asoofi1 said:


> @BrolicBeast did a really nice job with his absorption panels and overhead speakers...he basically made cloud panels with the speakers baffled in the panel...hides the speakers and absorbs
> 
> http://www.avsforum.com/showthread.php?t=1498937


Link is dead.




dnoonie said:


> The GIK may have a slight performance advantage being a little thicker. It looks like the Vicoustic might be $125 for a box of 6? http://store.acousticfrontiers.com/Vicoustic-Multifuser-DC2.html, it's hard to tell, it saw 6 units per box in the .pdf. I'd get the one that's the least expensive, one is about half the price as the other.
> 
> Please post back with what you find.
> 
> Cheers,


The acoustic frontier store is $125 per panel. I found a place in the UK that has them for $58 each in a case of six. I don't know why the US distributors are so much higher, but for those prices I don't mind paying the shipping and waiting a week or two. The GIK come out to $53 a piece plus shipping.


----------



## dnoonie

Molon_Labe said:


> I posted this in the Atmos section and figured I would post here too in hopes of receiving the most feedback.
> 
> Vicoustic Multifuser DC2
> 
> GIK GridFusor
> 
> Thoughts? Pro/Cons to either or?


http://www.audioasylum.com/cgi/vt.mpl?f=rives&m=6350

In the above thread one person like the skyline better and another the QRD design better...go figure.

http://www.audioasylum.com/cgi/vt.mpl?f=rives&m=6350
https://forum.audiogon.com/discussions/difference-b-w-rpg-skyline-and-gik-qrd-diffusors
https://www.gearslutz.com/board/bas...oam-etc/465799-qrd-skyline-tracking-room.html
http://www.acousticfields.com/whats-difference-skyline-sound-diffuser-quadratic-diffuser/
https://www.google.com/search?q=13-root+diffusors&ie=utf-8&oe=utf-8#q=qrd+vs+skyline+diffuser


My thoughts:
The skyline tends to be non-directional. The QRD (GIK) is most certainly directional and must be positioned with the slats at a right angle to the direction of the sound to function.

Also of note is that the GIK grid fusor is a mirror image diffusor making it easier to place as apposed to the larger 2'x4' QRD that must be place mirror image to each other if using more than one next to each other making a rather large 4'x4' array.

So depending on cost and your application you need to make a choice.

Cheers,


----------



## erkq

JDontee said:


> I was thinking the same thing. Fabric, batting, chicken wire, roxul and trim on the ceiling edges.



You *may* be over-thinking this. Rolls of fluffy insulation are held in place between floor joists using "lightening rods". It's very simple. The width of the roll makes a nice friction fit into the bays between joists and then the rods just help make sure it stays there.

BTW... I'm thinking of doing a similar thing in the walls. 2" thick acoustic panels with a 2" stand-off will perfectly fit the 4"available between the back sheetrock and surface of the front sheetrock.


----------



## SherazNJ

@dnoonie, hoping you or someone else can guide me here. I have a 21x12x8 dedicated completely closed theater room. I treated the front wall completely behind the AT screen and also covered the first reflection points on side and ceiling. For the back wall, I installed 1" thick linacoustic across the whole back wall and bass traps (8" rockwool) in the corners. I also have 1" thick linacoustic covering the area behind the surround speakers (90 degrees from MLP). I sit ~5 feet away from back wall. 
After all the calibration, I tested and found out that when I played a clip from youtube (2 channels LeftRight only), it was missing the brightness. I was comparing the sound by first listening in my headphone and then in the room. In headphone, the sound was more alive than in room. After reading around, I found out that the bass traps needs to be covered with FRK to reflect mid/high frequencies. I'll do that. But what about the 1" linacoustic? Should I leave them covering the back wall and also behind the surround speakers? 

By the way I have a 11.2 system. I can provide REW readings and also the pics if that'd help.

Much appreciated.
Regards,
Sheraz.


----------



## dnoonie

SherazNJ said:


> I installed 1" thick linacoustic
> But what about the 1" linacoustic? Should I leave them covering the back wall and also behind the surround speakers?
> 
> .


In general 1" will just filter high frequencies, minimum 2" is whats recommended. Perhaps someone more familiar with the Linacoustic product can speak to that.

With a room that size you should be able to use diffusion pretty easy, diffusion instead of absorption will certainly provide a more lively sound.

Cheers,


----------



## SherazNJ

dnoonie said:


> In general 1" will just filter high frequencies, minimum 2" is whats recommended. Perhaps someone more familiar with the Linacoustic product can speak to that.
> 
> With a room that size you should be able to use diffusion pretty easy, diffusion instead of absorption will certainly provide a more lively sound.
> 
> Cheers,


Thx for getting back to me. I read many posts including yours about the back wall. You recommended to others to install a 4" fiberglass. What gets me confused is what we are trying to achieve. I am clear about the front wall. It needs to be as dead as possible so nothing reflects back from it. For side wall b/w MLP and screen, cover the 1st reflection points. All this is clear. What is it we are trying to achieve from back wall? 

Please note that I have no issue in low frequency. Pretty much from 8Hz to 300Hz, all get resloved withing 300ms (Waterfall). Also in Decay no issue. So in low frequency, I think I'm golden. Here are the waterfall of center. Please notice that I'm running my subs 8db Hot.

*300Ms*









*450Ms*










So now, what do we do with the back wall? What issues can it cause knowing its 5 feet away from MLP? 

Also, can you recommend what diffuser would be good to go with?
Thx


----------



## dnoonie

The rule of thumb for diffusion is to have a foot of space from the diffusion for each inch of thickness. With a room that wide you may likely be able to do that.

http://www.gikacoustics.com/product-category/diffusion-products/
http://www.acousticsfirst.com/diffusers-diffusors.htm
http://www.atsacoustics.com/acoustic-diffusers.html
http://realtraps.com/diffusor.htm

Deadwood theater build, http://www.avsforum.com/forum/19-de...ion/1179128-deadwood-theater-comes-alive.html, uses an acoustics first diffusor that is 4" thick if I remember right, a nice option for smaller spaces than some.

Cheers,


----------



## asarose247

ATMOS to SCATMOS , on ceiling
ATMOS tops @ 45 make a 7 ft square, per spec wrt MLP
squeezed in the synthed set of TM
4 Volt 6''s at the corners, Klipsch SLX for TM
the dolby test /demo disk pings all 6 tops
props to @sdurani and @Scott Simonian

The total 40 sq ft, 5"+ thick clouds , 2" 703 base with a layer of Roxul on top, a lite wooden frame on top for fabric attachment, spaced for "equitable" off-axis dispersion mitigation

clouds are removable thru the center opening( I want another layer of AT fabric to break up all that (lovely) deep red

creates a noticeable cone of "quite a lot of more quiet" and cuts of a lot of off axis sound that might otherwise muddy things up.

a question: when running XT32, the mic points straight up, originally wrt setting up 7.1 plus FW, FH etc.
NOW it's being directly blasted at by the ATMOS speakers and the AVR gains geet rather high.

Any body see what the problem might be here.


----------



## Scott Simonian

Wow! Nice work, Wil.

Let XT32 do it's thing... then tweak to your heart's content.


----------



## SherazNJ

dnoonie said:


> The rule of thumb for diffusion is to have a foot of space from the diffusion for each inch of thickness. With a room that wide you may likely be able to do that.
> 
> http://www.gikacoustics.com/product-category/diffusion-products/
> http://www.acousticsfirst.com/diffusers-diffusors.htm
> http://www.atsacoustics.com/acoustic-diffusers.html
> http://realtraps.com/diffusor.htm
> 
> Deadwood theater build, http://www.avsforum.com/forum/19-de...ion/1179128-deadwood-theater-comes-alive.html, uses an acoustics first diffusor that is 4" thick if I remember right, a nice option for smaller spaces than some.
> 
> Cheers,


As I was exploring diffuser options, I read posts where FRK was mentioned. The point that was made was that bass traps absorb not only low but mid/high frequencies and installing FRK on bass traps will reflect mid/high frequencies and let the low frequencies go. So I ordered FRK paper. Got them 2 days ago and glued them on the bass traps that are installed in rear room corners. After that, did a lot of listening and what a difference . Much better now. I feel my room being bigger in the back while listening. I currently have Bi-polar rear surrounds and may be they are interacting with the FRK as well. I'll be replacing rear-surround with mono soon (order already in place and waiting for their arrival). So overall, the room feels much more alive now. 

Now after this, do you think I should still get diffusers and install them on the side walls in b/w MLP and back wall? Would it make room sound even bigger or it can cause problems since I have FRK on back bass traps now? If I install them on side wall, they will be about only 1' away from the bass traps. 

Thx.


----------



## dnoonie

SherazNJ said:


> Now after this, do you think I should still get diffusers and install them on the side walls in b/w MLP and back wall? Would it make room sound even bigger or it can cause problems since I have FRK on back bass traps now? If I install them on side wall, they will be about only 1' away from the bass traps.
> 
> Thx.


I'm glad the FRK helped. I placed QRDs over mine.

More diffusion? I'd say yes if you have the space, it sounds like you do. I tried diffusion in my room at first reflection points and I simply don't have the space in the front, my imaging was smeared once QRDs were placed at first reflection points. I have QRDs in the back first and second reflection points though and I really like what it does for the surround channels. see pics (yes the couch is unattractive and dated), since the picture was taken all but one pair of diffusors have been finished and I still need to raise/hang/rig the set under the surrounds and the set beside the front mains.

I bought mine, with various placement ideas but not knowing exactly where they were going to work, then found places they worked.

Cheers,


----------



## BasementBob

SherazNJ said:


> As I was exploring diffuser options, I read posts where FRK was mentioned. The point that was made was that bass traps absorb not only low but mid/high frequencies and installing FRK on bass traps will reflect mid/high frequencies and let the low frequencies go.


The FRK will also resonate at some frequency giving explicit narrow-band membrane behavior that is VERY dependent of the application/mounting itself measurable even with the expected damping, giving non linearity of absorption. 



SherazNJ said:


> So I ordered FRK paper. Got them 2 days ago and glued them on the bass traps that are installed in rear room corners. After that, did a lot of listening and what a difference . Much better now.


But I'm not going to argue with success.  If it works, don't 'fix' it because of something written on the internets. 

For some people, FRK with the paper/foil side room side, works very well. Improving the room's clarity and definition. And the strange pressure one sometimes feels on ones ears is gone. It really feels as a fresh room.


----------



## SherazNJ

dnoonie said:


> I'm glad the FRK helped. I placed QRDs over mine.
> 
> More diffusion? I'd say yes if you have the space, it sounds like you do. I tried diffusion in my room at first reflection points and I simply don't have the space in the front, my imaging was smeared once QRDs were placed at first reflection points. I have QRDs in the back first and second reflection points though and I really like what it does for the surround channels. see pics (yes the couch is unattractive and dated), since the picture was taken all but one pair of diffusors have been finished and I still need to raise/hang/rig the set under the surrounds and the set beside the front mains.
> 
> I bought mine, with various placement ideas but not knowing exactly where they were going to work, then found places they worked.
> 
> Cheers,





BasementBob said:


> The FRK will also resonate at some frequency giving explicit narrow-band membrane behavior that is VERY dependent of the application/mounting itself measurable even with the expected damping, giving non linearity of absorption.
> 
> 
> 
> But I'm not going to argue with success.  If it works, don't 'fix' it because of something written on the internets.
> 
> For some people, FRK with the paper/foil side room side, works very well. Improving the room's clarity and definition. And the strange pressure one sometimes feels on ones ears is gone. It really feels as a fresh room.


Update: After having FRK, I did get a lot more liveliness in the back of room. Yesterday, I did some Major Music listening testing. I realized that the higher frequencies were getting more treble than they needed to. I wonder if that's because FRK on back base traps is facing directly LR on the front. LR are towed in to MLP and rear bass trap makes a perfect angle to face LR. So even though it makes the rear part of room the way I like it, it is also causing this higher treble on HIGH volumen. I like volume high enough where I feel the singer is right in front of me and I increase the volume until I get that effect. At that point, high treble was causing distraction. I don' think I can say the same for the movies though since most of the dialog comes from Center. 

So what's the solution? Should I get rid of FRK paper from bass traps since they are facing the LR? Then install a pair of Diffisers on the side walls in b/w MLP and back wall? Would that bring the same liveliness and also get rid of that high treble effect?


----------



## pias

*Confirmed believer*

I've read it - - - You've read it - - - 

Put up six panels last week , three down each side at the appropriate spots (room is 14' x 24' x 8') and ( enthusiastic testimony) holy $hit what a nice improvement ! At higher SPL, no more smearing . 

Very satisfied. I was a little skeptical but now I'm a firm advocate. If you're thinking about panels, do it. More effective and a cheaper than most electronic dodads. ( I've had dodads)

Next, on to Atmos.


----------



## BasementBob

SherazNJ said:


> Update: After having FRK, I did get a lot more liveliness in the back of room. Yesterday, I did some Major Music listening testing. I realized that the higher frequencies were getting more treble than they needed to. I wonder if that's because FRK on back base traps is facing directly LR on the front. LR are towed in to MLP and rear bass trap makes a perfect angle to face LR. So even though it makes the rear part of room the way I like it, it is also causing this higher treble on HIGH volumen. I like volume high enough where I feel the singer is right in front of me and I increase the volume until I get that effect. At that point, high treble was causing distraction. I don' think I can say the same for the movies though since most of the dialog comes from Center.
> 
> So what's the solution? Should I get rid of FRK paper from bass traps since they are facing the LR? Then install a pair of Diffisers on the side walls in b/w MLP and back wall? Would that bring the same liveliness and also get rid of that high treble effect?


 
I don't know.


A couple guesses though. The paper on the FRK is quite light, so would tend to reflect only the highest frequencies. I don't have a definition for 'highest' in terms of hz.


So you could make the paper heavier, such as by spray adhesive gluing foil to it. (something like this? http://www.atticfoil.com/index.php/...ed-atticfoil-radiant-barrier-foil-perforated/ ) That would lower the reflected frequencies.


You could put something in front of the FRK to reflect more frequencies. If you have three 2x4's per 2'x4' FRK panel (2' wide by 4' tall, so wood 2x4s cover almost half the surface of the FRK), you could lean them in front of the panel spaced unevenly but left-right-room-symmetrically and see what that sounds like. The lean might deflect some of the reflected sound upwards, and the thickness of the wood would reflect more frequencies than the paper of the FRK. Anything under 500hz will ignore the wood completely and just go around it as if it wasn't there. Anything over 8000 hz will be specularly reflected by the 2x4s. And any frequency between 500hz and 8000hz, especially 4000hz, should have diffraction effects relative to those two limits. (As I recall, spray adhesive gets on everything -- don't spray it in a room with carpet)


----------



## SherazNJ

BasementBob said:


> I don't know.
> 
> 
> A couple guesses though. The paper on the FRK is quite light, so would tend to reflect only the highest frequencies. I don't have a definition for 'highest' in terms of hz.


So here is the site I purchased the paper from http://www.buyinsulationproductstore.com/frk-paper-pack-of-12-sheets/. I don't want to increase the reflection. Just want to tame it down a bit. For that, I made even holes in the paper to make it less reflective. The wave that goes through the hole will get absorbed my the panel and the one that hits the surface will get reflected. 

One very interesting observation though. I have 1" Linacoustic that is covering the side walls behind Surround Sound speakers are some more (4' wide area). I had to remove this 1"Linacoustic for some wall repair. Later I decided to watch a movie and the room had major reflection going. Then I put that 1"Linacoustic back and it tamed the reflection down to a much pleasing level. 

One thing I observed is how nicely the sound blossoms in the back of room. My wife said to me yesterday that it sounds like IMAX in the room . The back wall pretty much disappears. And if I take off that FRK paper then it gets very absorptive. What a big difference this FRK papar made. I purchased the bunch (10 sheets) for 30.00 only and used only two sheets and it paid off big time. Now I just need to tame it a little bit to make sure it doesn't get in the way of clarity of sound.


----------



## myfipie

Molon_Labe said:


> I posted this in the Atmos section and figured I would post here too in hopes of receiving the most feedback.
> 
> For those who have Atmos/DTS:X and treated ceilings, what did you use? I plan to use the typical absorption panels between the mains and front Atmos speakers to handle first reflections, but I am thinking of using diffusion for the section in between the ceiling speakers. I am torn between two products. I really like the DC2 the most because it just "looks awesome" on the ceiling. However, the primary goal is the treatment so I won't go with the "cooler" of the two. I could use any feedback from those who have gone down this road before. Here are the two models I have narrowed my choices to. I am also open to using absorption in the middle instead if that is the optimal choice. I just figured diffusion would open up the Atmos/DTS:X sounds stage above the two rows of seating, but I am by no means qualified to make that assumption. Ceiling is 9ft. I know diffusion is typically only recommend for 10+ feet ceilings, but I wasn't sure if Atmos has impacted that standard design principle or not.
> 
> Vicoustic Multifuser DC2
> 
> 
> 
> GIK GridFusor
> 
> 
> 
> Thoughts? Pro/Cons to either or?


The top is more based on a 2D diffuse where ours (the Gridfusor) is 1D. What that basically means is with a 2D the sound is scattered to the left, right and up and down vs 1D that throws it only left and right or up and down. Generally when we work do designs for listening rooms, home theaters and so on, we go with 1D as we want to control the sound better after it "reflects" off the diffusor. 2D is great for live rooms mostly, IMO.


----------



## myfipie

SherazNJ said:


> As I was exploring diffuser options, I read posts where FRK was mentioned. The point that was made was that bass traps absorb not only low but mid/high frequencies and installing FRK on bass traps will reflect mid/high frequencies and let the low frequencies go. So I ordered FRK paper. Got them 2 days ago and glued them on the bass traps that are installed in rear room corners. After that, did a lot of listening and what a difference . Much better now. I feel my room being bigger in the back while listening. I currently have Bi-polar rear surrounds and may be they are interacting with the FRK as well. I'll be replacing rear-surround with mono soon (order already in place and waiting for their arrival). So overall, the room feels much more alive now.
> 
> Now after this, do you think I should still get diffusers and install them on the side walls in b/w MLP and back wall? Would it make room sound even bigger or it can cause problems since I have FRK on back bass traps now? If I install them on side wall, they will be about only 1' away from the bass traps.
> 
> Thx.


Diffusion will trick the brain into thinking the room is larger so yes, but you need a lot of them. What is the size of your room? If you have listed all of that can you give me the thread link?


----------



## SherazNJ

myfipie said:


> Diffusion will trick the brain into thinking the room is larger so yes, but you need a lot of them. What is the size of your room? If you have listed all of that can you give me the thread link?


Good to hear from you. I have a 12x21x8 room. I am a firm believer that the room can make or break a HT. Therefore, I have been very focused into making my HT room as good as I can make it. 

Currenlty, I have all of the first reflection points covered with 4" RockWool DIY panels. But they are all covered with Black Velvets to make them disappear. I was a bit concerned about black velvet reflecting the sound and therefore, I made a lot of holes in velvet cloth to make sure they don't reflect the sound. I also have 4 cloud panels. The front wall is completely covered with 1" Linacoustic. Besides that, I have 4 4" Rockwool panels placed on side for Center speaker and one sitting on top of it. It was done to get rid of some dips center speaker was causing. 

I have all four corners of room covered with DIY bass traps. Each basstrap is 8" thick using Rockwool. Besides that, I have 1" Linacoustic covering side walls from MLP to back wall. Also 1" Linacoustic covering the area right behind MLP.

So that's my room. Recently, I added FRK paper on the rear corner basstraps. After that I felt room getting much larger sound in the back but then it was also getting some hig frequency reflection (subjective listening). So I ended up making holes in FRK paper to make it less reflective. I also made sure that FRK is covering only the panel that is covering the area from top of ceiling to MLP height. the bottom panel has no FRK. 

So far, it sounds good. But I'd like to to get more open sound in the rear. Yesterday, I ordered two diffusers from GIK http://www.gikacoustics.com/product/gik-acoustics-q7d-diffusor/. I am planning to place them on the side wall in b/w MLP and rear wall. 

Any advice from you is much appreciated.


----------



## dnoonie

myfipie said:


> Diffusion will trick the brain into thinking the room is larger so yes, *but you need a lot of them.* What is the size of your room? If you have listed all of that can you give me the thread link?


So would diffusion above the front speakers or above the MLP help add to the rooms apparent size? If so would 1d work okay? And I would guess that gridfusors over the speakers would be oriented with the wells running the length of the room or perhaps alternating? I'd think the ones over the MLP would be oriented against the direction of the sound? Thanks!

Cheers,


----------



## HopefulFred

SherazNJ said:


> first reflection points covered with 4" RockWool DIY panels.
> 4 cloud panels.
> The front wall is completely covered with 1" Linacoustic.
> 4" Rockwool panels placed on side for Center speaker and one sitting on top of it. It was done to get rid of some dips center speaker was causing.
> I have all four corners of room covered with DIY bass traps. Each basstrap is 8" thick using Rockwool.
> Besides that, I have 1" Linacoustic covering side walls from MLP to back wall.
> Also 1" Linacoustic covering the area right behind MLP.
> 
> Recently, I added FRK paper on the rear corner basstraps. After that I felt room getting much larger sound in the back but then it was also getting some high frequency reflection (subjective listening). So I ended up making holes in FRK paper to make it less reflective. I also made sure that FRK is covering only the panel that is covering the area from top of ceiling to MLP height. the bottom panel has no FRK.
> 
> So far, it sounds good. But I'd like to to get more open sound in the rear. Yesterday, I ordered two diffusers from GIK http://www.gikacoustics.com/product/gik-acoustics-q7d-diffusor/. I am planning to place them on the side wall in b/w MLP and rear wall.


Obviously I'm not Glenn, and his advice has much more experience and weight behind it, but I would like to weigh in here a little.

What I'm hearing you say is that you may have sucked a little too much high frequency energy out of the room. What I'm seeing is that you have 1" treatments in places that are not producing reflections that you can hear discretely (that's a bad way to say what I'm getting at). The 1" treatments on the side walls above and below ear height are absorbing high frequency sound that would potentially reflect twice or more before arriving at your ears. This is the sort of reflection that will lead to the perception of larger spaces. Diffusing a primary reflection has the effect of delaying it while preserving more of the energy, creating a sense of spaciousness as well. What I'm saying is that I think by reflecting as opposed to absorbing, especially with 1" material, at secondary and tertiary points, such as basically anywhere substantially above or below ear height, you might get directly to your solution.

I would take the 1" linacoustic from the side walls and use that to quadruple the thickness of the rear wall treatment, then remove the FRK from the ear-level portions of the bass traps.

Fred


----------



## SherazNJ

HopefulFred said:


> Obviously I'm not Glenn, and his advice has much more experience and weight behind it, but I would like to weigh in here a little.
> 
> What I'm hearing you say is that you may have sucked a little too much high frequency energy out of the room. What I'm seeing is that you have 1" treatments in places that are not producing reflections that you can hear discretely (that's a bad way to say what I'm getting at). The 1" treatments on the side walls above and below ear height are absorbing high frequency sound that would potentially reflect twice or more before arriving at your ears. This is the sort of reflection that will lead to the perception of larger spaces. Diffusing a primary reflection has the effect of delaying it while preserving more of the energy, creating a sense of spaciousness as well. What I'm saying is that I think by reflecting as opposed to absorbing, especially with 1" material, at secondary and tertiary points, such as basically anywhere substantially above or below ear height, you might get directly to your solution.
> 
> I would take the 1" linacoustic from the side walls and use that to quadruple the thickness of the rear wall treatment, then remove the FRK from the ear-level portions of the bass traps.
> 
> Fred


Hi Fred,
Thank you sooooo much for your advice. Its going to be a rather long post so please hang in there but the end results are very interesting. 

Even before I read your post, I realized something. The distance between MLP and the screen is ~10.5 feet. In between I have 3 panels (2x4 using 4" Rockwool) on each side wall and 4 panels on ceiling. So basically, most of the surface is covered. The front stage was not a problem for me because I don't like ambient sound for the front and like to hear very clean and focused sound. When I say focused, I mean sound that feels like it is only a foot away from me or as if one has Head Phone on. So that was working well. In the rear though, I like to hear the ambient sound and that's what I was chasing. 

My 4 feet wide panel with 1" Linacoustic (for simplicity sake, let's call it the surround panel) that was placed on side wall behind surround speaker was touching the last (3rd) panel on side wall . With surround panel in place, there was no surface exposed in b/w last panel on the front and surround area going to rear. At this point, it was a little too dead. When I decided to install FRK on rear bass traps, I also got rid of the surround panel. Did the subjective testing and it was good but was a little too ambient in the back and was also mixing with the front stage of sound. The imaging wasn't perfect and was pulling my attention more to the back of room than front. It was like a war in b/w the front of the room and back of the room. It wasn't a perfect sound bubble. 
Then I decided to put the surround panel back and tested. Now it was better and wasn't pulling my attention to the back of room and imaging was much more balanced but lacked a bit of ambiance. Finally I moved the surorund panel 2 feet away from 3rd panel on the side wall. This exposed some area in between the last panel on side wall and surround speakers. Now muuuuuch better. This last change I did day before yesterday and I knew that the PERFECT imaging is somewhere in there. 

Then I read your post and you made a very good point. You pointed out to get rid of 1" Linacoustice from above and below ear level from surround panel. After I read your post, I wondered about why I didn't think of that. Simply Genious. Yesterday after I got home from work, I took out the surrund panel and got rid of Linacoustic above and below MLP. Did the listening. Mucch better result but I wanted the Front stage a bit more prominent. Finally moved Surround Panel back to its original place where it was touch the 3rd Panel on side wall though this time I am only covering the area that is at ear level. Did the listening and there it is. Very good. Very good indeed. A very well balanced imaging. Just enough ambiance in the rear of room that makes is sound Live and full and makes the room BIG and at the same time not too bright to catch my attention or deviate from the front stage. Front stage was also solid. Everything sounded as I wanted it to. Niceeeeeee.

I did my listening testing for like 30 minutes with a movie. Over the weekend I'll do more listening. This is exciting. Funny that I'm getting the Diffusers today. I'll put them on the rear wall and see if they make a better difference. If not, then I all good. I can just pocket that extra $500.00 . 

One observation I'd like to share. I have FRK paper on one of the rear panel that is placed from Floor and going a little above the ear level (2x4). If I take out FRK form it, room sounds smaller in back and when I place it back on, it makes it bigger without causing any distraction. Don't know how its happening but that's what I observed. I think the sound reflects back and forth b/w FRK and couch back seat (leather seats) and then eventually hit the back wall that has absorption and gets absorbed. This bouncing creates enough ambiance to make room sound larger IMO. 

Now finally a question. 


> I would take the 1" linacoustic from the side walls and use that to quadruple the thickness of the rear wall treatment, then remove the FRK from the ear-level portions of the bass traps.


 Would I be better to do the doubling on 703 Fiber instead? I don't have any low frequency room ringing though.

Thanks Fred for your great advice. Much appreciated.


----------



## HopefulFred

SherazNJ said:


> Would I be better to do the doubling on 703 Fiber instead? I don't have any low frequency room ringing though.


I don't have any expertise in the material choice at all. I would simply use what I already had. My general hunch is that most of the time the difference between one fibrous material and another is hardly measurable.


----------



## BasementBob

You can somewhat compare "703 plain" vs "703 FRK" at
http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## SherazNJ

BasementBob said:


> You can somewhat compare "703 plain" vs "703 FRK" at
> http://www.bobgolds.com/AbsorptionCoefficients.htm


Thx. I wish I could find a place to buy 703 FiberGlass in Central Jersey. I know a place but its over an hour away. Renting a truck and going this far will almost cost me same as paoying 40.00 for shipment.


----------



## Kartiknibjiya

Hi friends,

I am setting up a 5.1.4 home theatre in a dedicated room in my new flat with Dolby Atmos.
Room layout is attached alongwith this post
Room size is 14.5ft x 10.5ft and height till false ceiling is 8.5ft. 
Screen will be on wall measuring 10.5ft. 
On this 10.5ft wall, 7.75ft x 4ft window is also there, that why I am going for motorised screen. Screen and front floor standing speakers will come in front of this window and centre speaker below screen. My purpose for home theatre is for viewing 70% movies or live sports screening and rest 30% music.

Speaker system will be PSB X2 T - Floor Standing TOWER (PAIR)
PSB XC - CENTER
PSB XB - REAR SPEAKERS (PAIR)
PSB SUB 200
PSB CW 80 R (2 PAIRs) In Ceiling 

My PSB Imagine X2T floorstanding speaker's frequency response Off Axis @ 30°±1 1/2dB is 45-10,000Hz. 

I want to setup floor carpet matt and acoustics wall panels for getting the best sound. 

Please advice me on the same. 

How should i go about to get the best sound experience ? I also want a good aesthically looking room.. Do I need Complete Absorbption in the room with Bass Trappers / partial Diffusion etc etc.. 

Other than this, my query is that whether diffusion is needed on back wall ??

One of the acoustic consultant told me that only absorption will be required for your home theatre room as your room is not long enough but just 14.5ft. So he said 2inch absorption with glasswool covered with foam covered with fabric will do fine. Will this work? He said diffusion is not needed as room is not big enough lenghtwise. Is it true ?

While another said, we will do absorption in only reflection points and corners and not the whole room.. 

While a third person in the forum told me this :
As my left side and right side wall is 14.5ft and front and back wall measures 10.5ft and height of room is 8.5ft, therefore use :

0. Front wall : use 2inch thick glasswool panel (80kg density) with 1" air gap -> total 3 inch
1. Side wall next to speaker : use 2inch thick glasswool panel of about 5 feet from front wall to absorb early reflections
2. Sliding glass Window on front wall : window to cover with door of acoustic panels on inside... that is,to make panel covered small doors over that front wall window so that when needed that window door could be covered when Hometheatre is running.
3. Centre Side Wall (from 5ft to 9ft ) : What acoustic treatment i should do here ??
4. Rear side of Side Wall (from 9ft to 13.5ft) : to use some 2" 3d diffusion
5. Rear Corner(13.5ft to 1ft on rear wall) : to use Thick Bass trap filled with glasswool (1ft equilateral triangle in corner)
6. side of the back wall (1ft to 3.5ft => total 2.5ft on left side of rear wall and again from 7ft to 9.5ft => total 2.5ft on right side of real wall) - to again use 2" 3d diffusion
7. middle of the back wall (from 3.5ft to 7ft => total 3.5ft on back wall) -> to use 2inch thick glasswool panel (80kg density) with 1" air gap -> total 3 inch
8. cover the entire floor with thick carpet
9. leave the false ceiling (made of gypsum) untouched 


So 3 different opinions and hence i am confused ... friends plz give your advice 

How should i go about to get the best sound experience ? I also want a good aesthically looking home theatre room.. Do I need Complete Absorbtion in the room with Bass Trappers / partial Diffusion etc etc..


----------



## audiovideoholic

Can anyone tell me or link me to ways of making fabric/acoustical panels that are curved. Like picture cutting a hollow sphere in half and looking "into" the half. I can easily come up with ways to make 3D type panels where the fabric has its highest point on the outside but I'm looking to do the opposite. I want to create designs where the fabric will be sunk in towards the wall cavity. 

Any ideas for AT fabric shaped panels? It could come down to design and only have the cavity portions with flexible material that won't need speakers there.

This is where I got the inspiration and know I will not be able to come anywhere near this but using some of its concepts would be very appealing. 

cineramax europa and imax images

https://plus.google.com/113945651896135127512/posts/X8SQqwEAiJu


http://cineramax.com/projects/europa/


----------



## Kartiknibjiya

Kartiknibjiya said:


> Hi friends,
> 
> I am setting up a 5.1.4 home theatre in a dedicated room in my new flat with Dolby Atmos.
> Room layout is attached alongwith this post
> Room size is 14.5ft x 10.5ft and height till false ceiling is 8.5ft.
> Screen will be on wall measuring 10.5ft.
> On this 10.5ft wall, 7.75ft x 4ft window is also there, that why I am going for motorised screen. Screen and front floor standing speakers will come in front of this window and centre speaker below screen. My purpose for home theatre is for viewing 70% movies or live sports screening and rest 30% music.
> 
> Speaker system will be PSB X2 T - Floor Standing TOWER (PAIR)
> PSB XC - CENTER
> PSB XB - REAR SPEAKERS (PAIR)
> PSB SUB 200
> PSB CW 80 R (2 PAIRs) In Ceiling
> 
> My PSB Imagine X2T floorstanding speaker's frequency response Off Axis @ 30°±1 1/2dB is 45-10,000Hz.
> 
> I want to setup floor carpet matt and acoustics wall panels for getting the best sound.
> 
> Please advice me on the same.
> 
> How should i go about to get the best sound experience ? I also want a good aesthically looking room.. Do I need Complete Absorbption in the room with Bass Trappers / partial Diffusion etc etc..
> 
> Other than this, my query is that whether diffusion is needed on back wall ??
> 
> One of the acoustic consultant told me that only absorption will be required for your home theatre room as your room is not long enough but just 14.5ft. So he said 2inch absorption with glasswool covered with foam covered with fabric will do fine. Will this work? He said diffusion is not needed as room is not big enough lenghtwise. Is it true ?
> 
> While another said, we will do absorption in only reflection points and corners and not the whole room..
> 
> While a third person in the forum told me this :
> As my left side and right side wall is 14.5ft and front and back wall measures 10.5ft and height of room is 8.5ft, therefore use :
> 
> 0. Front wall : use 2inch thick glasswool panel (80kg density) with 1" air gap -> total 3 inch
> 1. Side wall next to speaker : use 2inch thick glasswool panel of about 5 feet from front wall to absorb early reflections
> 2. Sliding glass Window on front wall : window to cover with door of acoustic panels on inside... that is,to make panel covered small doors over that front wall window so that when needed that window door could be covered when Hometheatre is running.
> 3. Centre Side Wall (from 5ft to 9ft ) : What acoustic treatment i should do here ??
> 4. Rear side of Side Wall (from 9ft to 13.5ft) : to use some 2" 3d diffusion
> 5. Rear Corner(13.5ft to 1ft on rear wall) : to use Thick Bass trap filled with glasswool (1ft equilateral triangle in corner)
> 6. side of the back wall (1ft to 3.5ft => total 2.5ft on left side of rear wall and again from 7ft to 9.5ft => total 2.5ft on right side of real wall) - to again use 2" 3d diffusion
> 7. middle of the back wall (from 3.5ft to 7ft => total 3.5ft on back wall) -> to use 2inch thick glasswool panel (80kg density) with 1" air gap -> total 3 inch
> 8. cover the entire floor with thick carpet
> 9. leave the false ceiling (made of gypsum) untouched
> 
> 
> So 3 different opinions and hence i am confused ... friends plz give your advice
> 
> How should i go about to get the best sound experience ? I also want a good aesthically looking home theatre room.. Do I need Complete Absorbtion in the room with Bass Trappers / partial Diffusion etc etc..


hey friends,

please help !!


----------



## healthnut

I would start with corner bass traps and first reflection panels. I'd also refer you to the GIK acoustics website for more pointers. They also offer a free consulting service and are a solid and reputable company. I bought all my reflection panels and traps from them. Best of luck !


Sent from my iPhone using Tapatalk


----------



## dnoonie

Kartiknibjiya said:


> Hi friends,
> 
> I am setting up a 5.1.4 home theatre in a dedicated room in my new flat with Dolby Atmos.
> Room layout is attached alongwith this post
> Room size is 14.5ft x 10.5ft and height till false ceiling is 8.5ft.
> Screen will be on wall measuring 10.5ft.
> On this 10.5ft wall, 7.75ft x 4ft window is also there, that why I am going for motorised screen. Screen and front floor standing speakers will come in front of this window and centre speaker below screen. My purpose for home theatre is for viewing 70% movies or live sports screening and rest 30% music.
> 
> Speaker system will be PSB X2 T - Floor Standing TOWER (PAIR)
> PSB XC - CENTER
> PSB XB - REAR SPEAKERS (PAIR)
> PSB SUB 200
> PSB CW 80 R (2 PAIRs) In Ceiling
> 
> My PSB Imagine X2T floorstanding speaker's frequency response Off Axis @ 30°±1 1/2dB is 45-10,000Hz.
> 
> I want to setup floor carpet matt and acoustics wall panels for getting the best sound.
> 
> Please advice me on the same.
> 
> How should i go about to get the best sound experience ? I also want a good aesthically looking room.. Do I need Complete Absorbption in the room with Bass Trappers / partial Diffusion etc etc..
> 
> Yes, absorbers will be easiest, diffusion will be difficult in a room that small. I think it would be easy enough and sound good to use GIK bass traps with scatter plates in your corners.
> 
> Other than this, my query is that whether diffusion is needed on back wall ??
> 
> One of the acoustic consultant told me that only absorption will be required for your home theatre room as your room is not long enough but just 14.5ft. So he said 2inch absorption with glasswool covered with foam covered with fabric will do fine. Will this work? He said diffusion is not needed as room is not big enough lenghtwise. Is it true ?
> 
> I don't know about not needed because it's small it'll just be harder. If you want a more live sound you could likely use diffusion that isn't as thick and it would sound fine but only in certain areas. I wouldn't use diffusion at first reflection points for instance. Check the Deadwood build for some ideas, http://www.avsforum.com/forum/19-de...ion/1179128-deadwood-theater-comes-alive.html, http://www.avsforum.com/forum/92-community-news-polls/1834186-ht-month-deadwood-cinema.html.
> 
> While another said, we will do absorption in only reflection points and corners and not the whole room.
> 
> Not bad advice, it depends on your budget, do the above first, including ceiling, if you have the budget use corner bass absorbers with scatter plates and put some supper absorbers (6" or even thicker) on the back wall.
> 
> While a third person in the forum told me this :
> As my left side and right side wall is 14.5ft and front and back wall measures 10.5ft and height of room is 8.5ft, therefore use :
> 
> 0. Front wall : use 2inch thick glasswool panel (80kg density) with 1" air gap -> total 3 inch
> 1. Side wall next to speaker : use 2inch thick glasswool panel of about 5 feet from front wall to absorb early reflections
> 
> Find reflection points with a mirror, http://www.gikacoustics.com/video-early-first-reflection-points/
> 
> 2. Sliding glass Window on front wall : window to cover with door of acoustic panels on inside... that is,to make panel covered small doors over that front wall window so that when needed that window door could be covered when Hometheatre is running.
> 
> Stands can be used to put panels over a window or sliding glass door, they're called a gobo.
> 
> 3. Centre Side Wall (from 5ft to 9ft ) : What acoustic treatment i should do here ??
> 
> Behind first and second reflection points (more or less beside the MLP diffusion may work if you want it.
> 
> 4. Rear side of Side Wall (from 9ft to 13.5ft) : to use some 2" 3d diffusion
> 
> Is this a reflection point for surrounds? The rule of thumb for diffusion is 1 foot of distance for every inch of diffusion thickness, otherwise it can smear imaging.
> 
> 5. Rear Corner(13.5ft to 1ft on rear wall) : to use Thick Bass trap filled with glasswool (1ft equilateral triangle in corner)
> 6. side of the back wall (1ft to 3.5ft => total 2.5ft on left side of rear wall and again from 7ft to 9.5ft => total 2.5ft on right side of real wall) - to again use 2" 3d diffusion
> 
> That may work if you have the space/can find diffusion that will fit in the width.
> 
> 7. middle of the back wall (from 3.5ft to 7ft => total 3.5ft on back wall) -> to use 2inch thick glasswool panel (80kg density) with 1" air gap -> total 3 inch
> 
> I'd use a 6" bass trap there.
> 
> 8. cover the entire floor with thick carpet
> 9. leave the false ceiling (made of gypsum) untouched
> 
> Sounds good as long as your false ceiling is absorber type witch a lot are.
> 
> 
> So 3 different opinions and hence i am confused ... friends plz give your advice
> 
> I think the addition of my advice will simply give you another option. I don't see that the advice that you've been given already to be bad advice. I'm not going to tell you what to do, you need to decide. I created a dedicated theater room in 2013 and since then I've changed the treatments in some way about a dozen times and 3 times that much if you count experimental placement.
> 
> How should i go about to get the best sound experience ? I also want a good aesthically looking home theatre room.. Do I need Complete Absorbtion in the room with Bass Trappers / partial Diffusion etc etc..


Some resources,
http://www.gikacoustics.com/
http://www.acoustimac.com/
http://www.atsacoustics.com/
http://www.acousticsfirst.com/
http://realtraps.com/index.htm
http://www.primacoustic.com/

Cheers,


----------



## dnoonie

Kartiknibjiya said:


> How should i go about to get *the best sound experience* ? I also want a good aesthically looking home theatre room.. Do I need Complete Absorbtion in the room with Bass Trappers / partial Diffusion etc etc..


"...the best sound experience..." is very subjective. There isn't one answer. You need to decide what you like and then figure out how to create that sound in your space. Visit other theaters, here's what I did, http://www.avsforum.com/forum/173-2-channel-audio/2494714-my-audio-reference-2.html#post45058394

I started basic with 1" spaced 2" absorbers at first and second reflection points and corner 4" bass traps and developed from there.

How did I decide what to do?

I heard other rooms that I liked and tried to create an environment that would create the same experience in my theater room.

Cheers,


----------



## pacmanprince

Hello,

The door to my bedroom doesn't exactly fit the doorway, and has a small gap at the bottom from the floor where a lot of sound leaks out. I was wondering if I could get something of custom dimensions (basically a 3d rectangular shaped foam or something like that) which I will then affix to the bottom of the door with some 3M or something of that nature to "fill in" that gap. Do you guys know where/what I could get something to help my situation? Thanks for any help.


----------



## Mashie Saldana

pacmanprince said:


> Hello,
> 
> The door to my bedroom doesn't exactly fit the doorway, and has a small gap at the bottom from the floor where a lot of sound leaks out. I was wondering if I could get something of custom dimensions (basically a 3d rectangular shaped foam or something like that) which I will then affix to the bottom of the door with some 3M or something of that nature to "fill in" that gap. Do you guys know where/what I could get something to help my situation? Thanks for any help.


Hi, I suggest you ask this in the Soundproofing Master Thread.


----------



## pacmanprince

Mashie Saldana said:


> Hi, I suggest you ask this in the Soundproofing Master Thread.


Thanks, I posted there as well


----------



## dnoonie

Kartiknibjiya said:


> How should i go about to get the best sound experience ? I also want a good aesthically looking home theatre room.. Do I need Complete Absorbtion in the room with Bass Trappers / partial Diffusion etc etc..


I just remembered this guide over at http://www.primacoustic.com/app-home-theatre.htm, once you've figured out how live/dead a sound you want you can use the guide at the bottom of the write up to help you add absorption to taste. the pic below is a quick summary the write up has some great info.









More info, http://www.residentialsystems.com/a...asics-of-sound-control-in-home-theaters/86809

Cheers,


----------



## HarpNinja

Thoughts on these frames for DIY panels? http://www.atsacoustics.com/item--Fill-it-Yourself-Frame-24-x-36-x-2--1163.html

I'd be getting the 24x36" and am looking at the 2" for first (and second) reflection points on my side walls. My system isn't huge or fancy, but it does sit in a 33x20' room. The seating is 13.5' from the screen.

I was thinking of filling with something like Roxul and temporarily covering with a solid color fabric. At some point, I'd like to do the DIY movie posters, hence the 24x36" size.

Thanks!


----------



## Tom Riddle

I have an interesting new problem with my front sound-stage, and I'm not sure how to solve it. I went to a 75" from a 65", and it created a lot of reverb behind the set due to the way I have it mounted. It's on a pull-out swivel mount, about 1 foot away from the wall, and that space is creating some nightmares for my system. I can't push the set in all the way to the wall, as the speakers would block the side views. The only thought I have, is try to push the speakers closer to the wall to try to minimize, or install bass traps behind the center speaker and up to the tv mount. See pictures below - any thoughts?


----------



## dnoonie

HarpNinja said:


> Thoughts on these frames for DIY panels? http://www.atsacoustics.com/item--Fill-it-Yourself-Frame-24-x-36-x-2--1163.html
> 
> I'd be getting the 24x36" and am looking at the 2" for first (and second) reflection points on my side walls. My system isn't huge or fancy, but it does sit in a 33x20' room. The seating is 13.5' from the screen.
> 
> I was thinking of filling with something like Roxul and temporarily covering with a solid color fabric. At some point, I'd like to do the DIY movie posters, hence the 24x36" size.
> 
> Thanks!


I think your ideas are good ones. 

You should use acoustically transparent fabric.
Most acoustic panel sellers will print your image on acoustic fabric for you.
Some resources
http://www.gikacoustics.com/
http://www.acoustimac.com/
http://www.atsacoustics.com/
http://www.acousticsfirst.com/
http://realtraps.com/index.htm
http://www.primacoustic.com/

Cheers,


----------



## dnoonie

Tom Riddle said:


> I have an interesting new problem with my front sound-stage, and I'm not sure how to solve it. I went to a 75" from a 65", and it created a lot of reverb behind the set due to the way I have it mounted. It's on a pull-out swivel mount, about 1 foot away from the wall, and that space is creating some nightmares for my system. I can't push the set in all the way to the wall, as the speakers would block the side views. The only thought I have, is try to push the speakers closer to the wall to try to minimize, or install bass traps behind the center speaker and up to the tv mount. See pictures below - any thoughts?


Is the TV or objects around the TV rattling or...? Bass absorbers behind the speakers and screen wouldn't hurt but it could be that you've moved your speakers wider with the wider screen and that you're getting wall or room object reflections that are messing with your sound. You could try moving your speakers around to try to diagnose the problem(s), move them closer and or farther out in the room on a temp basis to see if the problem goes away, try temp moving objects that are close to the speakers to another room or to the back of the room to see if the problem goes away. Once you're found the issues you may consider side treatment of some sort (gobos if you can't hang them) or simply moving a couple objects in the room to a different location on a temp basis for serious listening.

Cheers,


----------



## Tom Riddle

Thanks for the response. I haven't moved the speakers, so the only change is the new tv, and this issue wasn't present with the old set in the same place and distance from the wall. Due to my room layout, I don't have any other options to change the speaker layout. This isn't a dedicated room, unfortunately.


----------



## HopefulFred

The size change for the TV seems unlikely to cause problems. More likely is setup. In particular, could it be that you are getting sound from both the TV and the tower speakers?


----------



## Tom Riddle

HopefulFred said:


> The size change for the TV seems unlikely to cause problems. More likely is setup. In particular, could it be that you are getting sound from both the TV and the tower speakers?


No, only the HT speakers are sending sound, nothing from the tv.


----------



## dnoonie

Tom Riddle said:


> Thanks for the response. I haven't moved the speakers, so the only change is the new tv, and this issue wasn't present with the old set in the same place and distance from the wall. Due to my room layout, I don't have any other options to change the speaker layout. This isn't a dedicated room, unfortunately.


What is the symptom? What do you hear or measure that's not right?

Cheers,


----------



## Tom Riddle

dnoonie said:


> What the symptom? What do you hear or measure that's not right?
> 
> Cheers,


I haven't had a chance to run any measurements. It sounds like reverb, something that mostly pronounces itself when male's are speaking, like the bass from the voice is bouncing around from the wall to the tv.


----------



## dnoonie

Tom Riddle said:


> I haven't had a chance to run any measurements. It sounds like reverb, something that mostly pronounces itself when male's are speaking, like the bass from the voice is bouncing around from the wall to the tv.


I'd suggest getting 2 bass traps. If the only acceptable location is behind the front main speakers/TV then put them there.

Do you have other room treatment?
Do you have any other location you could put treatment besides behind the main speakers/TV?

Cheers,


----------



## Tom Riddle

dnoonie said:


> I'd suggest getting 2 bass traps. If the only acceptable location is behind the front main speakers/TV then put them there.
> 
> Do you have other room treatment?
> Do you have any other location you could put treatment besides behind the main speakers/TV?
> 
> Cheers,


Thanks @dnoonie. The only other space that my wife would let me use would be the area behind the center. She puts up with my HT in her living room, but isn't happy about it. We are about to put in a pool, and she almost convinced me to scrap the pool for now and finish a true HT space over the garage because I'm driving her insane, lol. I would rather have the pool now and wait and put in the HT of my dreams a few years down the road.


----------



## dnoonie

Tom Riddle said:


> Thanks @dnoonie. The only other space that my wife would let me use would be the area behind the center. She puts up with my HT in her living room, but isn't happy about it. We are about to put in a pool, and she almost convinced me to scrap the pool for now and finish a true HT space over the garage because I'm driving her insane, lol. I would rather have the pool now and wait and put in the HT of my dreams a few years down the road.


Cool!

You could likely reuse any panels you get in the new space. Good luck with the new space!!

I doubt the initial issue is the screen, it's likely the back of the room in general and specifically the back corners, the larger TV simply added an element to make things a little worse. I hope that any treatment behind the TV and or center channel helps, it can't hurt.

Other ideas (room treatment that's not room treatment:wink:

Sculptures that are roundish (people, animals, a totem, etc.) can work as diffusion, the larger and more rounded the better.
Plants make great diffusion, again, bigger is better (a forest is amazingly diffuse)
Large round planters for your plants are good diffusion
Decorative, round pillars can also be diffusion
Furniture absorbs and diffuses
Through rugs (if you have a wood floor)
Avoid flat reflective objects

Cheers,


----------



## Tom Riddle

Thanks @ dnoonie. This room is a challenge, as it is open to the rest of the house and upstairs. I'm not really getting much back reflections, as the back walls are more than 20' from the back of the couch - see below pictures. I just need to find a temp. solution until I can build a dedicated space.


----------



## dnoonie

Tom Riddle said:


> Thanks @ dnoonie. This room is a challenge, as it is open to the rest of the house and upstairs. I'm not really getting much back reflections, as the back walls are more than 20' from the back of the couch - see below pictures. I just need to find a temp. solution until I can build a dedicated space.


Cool.

What about a pic or two of the ceiling? Could you put bass traps up there?

Cheers,


----------



## Tom Riddle

dnoonie said:


> Cool.
> 
> What about a pic or two of the ceiling? Could you put bass traps up there?
> 
> Cheers,


No, they are 20' high, and my wife is barely on board with putting traps in the front. I got a hold of GIK and ATS, and they both suggested I just stick to bass traps behind the towers and the center due to my constraints. My room is not an ideal space due to being so open, so I will go with any improvement until I can build a dedicated space.


----------



## dnoonie

Tom Riddle said:


> No, they are 20' high, and my wife is barely on board with putting traps in the front. I got a hold of GIK and ATS, and they both suggested I just stick to bass traps behind the towers and the center due to my constraints. My room is not an ideal space due to being so open, so I will go with any improvement until I can build a dedicated space.


Nice!

That room looks like a great party room! With it connected to the kitchen with the wet bar in between, very cool. My current theater room wasn't hardly functional as anything before the conversion, I'd like to create a space like that when I do an add on of a purpose built theater room.

I do think that the source of the problem is the ceiling area, and or short hall beyond the rail upstairs, but you can only do what you can. With the molding up there it would be difficult to impossible to have unobtrusive treatment. And the difficulty of hanging treatment would turn it into an obtrusive project.

If the problem persists you might consider EQ to tame the offending frequencies.

Cheers,


----------



## hobsocc7

I posted this in the build thread but this might be a better place for it.

http://www.avsforum.com/showthread.php?t=2527433

Is there anything special to do concerning a angled ceiling? The link above has a photo and basics on what I am planning for treatments (all diy)

Sent from my Nexus 6P using Tapatalk


----------



## myfipie

Tom Riddle said:


> No, they are 20' high, and my wife is barely on board with putting traps in the front. I got a hold of GIK and ATS, and they both suggested I just stick to bass traps behind the towers and the center due to my constraints. My room is not an ideal space due to being so open, so I will go with any improvement until I can build a dedicated space.


Yes that is a lot of blank wall area so you will naturally have a lot of upper frequency reflections (reverb). In the future, I would get some absorption (or diffusion) on the upper wall areas.


----------



## Tom Riddle

Thanks @myfipie. Unfortunately, those areas have been deemed off-limits by my wife. I do have two bass trap panels coming in from GIK, so we will see how that helps. I did have a contractor come in to see about finishing the upstairs media room - so I'm on the way at least. My wife is trying to steer me from adding a pool and just finishing that room. That's how tired she is of my HT hobby, lol.


----------



## donktard

Hey guys.
Are tuned membrane traps very effective for treating SBIR? I have a huge notch in response at 135 Hz which I believe is SBIR and would try to treat it by putting membrane trap at right location. Broadband panels don't help much.


----------



## Roger Dressler

donktard said:


> Are tuned membrane traps very effective for treating SBIR? I have a huge notch in response at 135 Hz which I believe is SBIR and would try to treat it by putting membrane trap at right location. Broadband panels don't help much.


Is it a side wall or ceiling bounce issue? A diagram or picture might help to confirm. But aside from that, it might more effective to diffuse the reflection. Just a thought.


----------



## donktard

Roger Dressler said:


> Is it a side wall or ceiling bounce issue? A diagram or picture might help to confirm. But aside from that, it might more effective to diffuse the reflection. Just a thought.


My left speaker is very close to the side wall and also right below slanted ceiling. That (slanted ceiling mostly, I believe) causes pretty chaotic response from 120 to 700 Hz (unlike on right speaker), but my movement options are pretty much non-existent.
I have early reflections treated, but my room configuration makes it kinda difficult for me to figure out the solution. Today I will try to play sine wave at offending frequency while measuring SPL at MLP and move acoustic panels around to see if anything will make a difference.

Also, how do you diffuse 135 Hz?


----------



## Tom Riddle

Got my panels in from GIK today - put them in temporary spots just to test, but will take measurements and move to the best spot later. I used TDKR as my demo, and I noticed a significant improvement right away. The bass is much more potent, with little reverb off the front wall, and all the rattles that were in the equipment rack are gone. Very nice! My wife hates them though - she is ready to call the contractor today and start on my HT room, lol. The contractor is coming back by on Tuesday with his structural guy to finish out my quote.


----------



## ddigler

Good morning all; hoping some of you room treatment experts can help me; I have some great advisers at my build thread but with some of the evolving/contradictory info regarding room acoustics I am soliciting as many viewpoints as possible: *Regarding front wall (behind false wall) treatment*: is the recommendation to make this area completely dead with absorption still the commonly accepted approach (for movies viewing in particular)?


----------



## HopefulFred

Reflected sound from the area of the image provides no benefit. In most cases, it is detrimental to both the frequency response and temporal precision of the front soundstage, as well as complicating management of the surround sound field. A baffle wall with surface absorption continues to be the gold standard, in my opinion.


----------



## ddigler

Thanks Fred very helpful


----------



## myfipie

donktard said:


> Hey guys.
> Are tuned membrane traps very effective for treating SBIR? I have a huge notch in response at 135 Hz which I believe is SBIR and would try to treat it by putting membrane trap at right location. Broadband panels don't help much.


Basically yes, but you have to put them in the right spot and it still does take some area (wall area) to fix. You can't just put a 2'x2' tuned panel on the wall and think it will fix the problem. Needless to say through broadband should work if thick enough. How thick are the panels you have now?


----------



## donktard

myfipie said:


> Basically yes, but you have to put them in the right spot and it still does take some area (wall area) to fix. You can't just put a 2'x2' tuned panel on the wall and think it will fix the problem. Needless to say through broadband should work if thick enough. How thick are the panels you have now?


I got 4" thick panels. I solved the problem partially today. I played 135 Hz tune and fixed SPL meter in place and then moved panels around until I gained some SPL


----------



## myfipie

donktard said:


> i got 4" thick panels. I solved the problem partially today. I played 135 hz tune and fixed spl meter in place and then moved panels around until i gained some spl :d


nice!!!


----------



## Skylinestar

Is there any bad effect if I cover my DIY basstrap / first reflection absorber with a layer of paper before I cover it with fabric?


----------



## climber07

Skylinestar said:


> Is there any bad effect if I cover my DIY basstrap / first reflection absorber with a layer of paper before I cover it with fabric?


Air is the audio medium. Air must be able to pass through a material for absorption to work. Paper will reflect the sound and act as a transducer.


----------



## HopefulFred

It is true that the paper will reflect some of the signal, but that's probably not a problem. Any bass or even midrange signal has so much energy that the paper will not have enough mass to reflect it. Only high frequency sounds can be reflected by paper. The effect of that will likely be that the audible portion of the reflection acts to broaden the acoustic image from the front soundstage. If you are in a mixing environment - not a home theater - the focus of the soundstage is probably very important, and you should avoid the paper. In a home theater, it's mostly a matter of preference.


----------



## Skylinestar

HopefulFred said:


> It is true that the paper will reflect some of the signal, but that's probably not a problem. Any bass or even midrange signal has so much energy that the paper will not have enough mass to reflect it. Only high frequency sounds can be reflected by paper. The effect of that will likely be that the audible portion of the reflection acts to broaden the acoustic image from the front soundstage. If you are in a mixing environment - not a home theater - the focus of the soundstage is probably very important, and you should avoid the paper. In a home theater, it's mostly a matter of preference.


Thanks.
So double wrapping the Roxul batts with fabric is still a better way to prevent the fibers from leaking out? 
With a single layer of fabric, the fibers can sometimes "poke through", pricking my fingers when I hold it.


----------



## HopefulFred

If paper seems too reflective for your taste, two layers of fabric may be the best choice - I can't speak to the effectiveness in terms of managing the fibers. You might also consider a very thin plastic film, like cling wrap. The lighter and thinner the membrane, the less significant its effect.


----------



## dnoonie

HopefulFred said:


> If paper seems too reflective for your taste, two layers of fabric may be the best choice - I can't speak to the effectiveness in terms of managing the fibers. You might also consider a very thin plastic film, like cling wrap. The lighter and thinner the membrane, the less significant its effect.


I like the idea of 2 layers of fabric. I'd be afraid of plastic or paper rattling. A layer of inexpensive acoustic transparent fabric, then your fabric of choice over that. I haven't concerned myself with it, most of my panels came with rockwool and only one layer of fabric, I've not been bothered when handling the panels, but then it could be the acoustic fabric that was used so your experience could be different.

Cheers,


----------



## hobsocc7

Can you use web adhesive? When I picked up the linacoustic from the HVAC place they said to buy that for the edges to prevent fibers for becoming airborne 

Sent from my Nexus 6P using Tapatalk


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## Skylinestar

I have a question regarding placement of bass traps. All guides say bass trapping is best done at boundaries & corners. In the example of this diagram, how thick should the wall material be to be considered as boundary & corner? If a house wall is made of a layer of thin wooden panel, does that equates to not having a wall at wall, hence bass trapping not required? If you were to place some bass traps, do you place it at the corners of that brick wall? or the corners of the dry wall? or the corners of the thinner walls?


----------



## jeff43

I have a 22' x 11.5' room, 7' ceilings with one short wall being the stairs leading to the basement. 22' wall is the TV wall.

Atmos set up with Atmos front speakers (yes, I know, ceiling height issue). Center surround speakers hung from ceiling, rear surround ear level on wall, seating 8' from screen. Center channel above screen. Two sub's. 

Plan on curtain that can be pulled to cover stair area while using system.

Obviously, this setup will be far from perfect but this is what I'm working with. 

My plan is 4 wedge bass traps in TV wall corners (ceiling, floor), area rug to fill most of room, all walls: hard surface (wainscoting) 3' high and cork top 4' of wall. TV wall will also have shelving on both sides as TV will be built into the wall as well. Ceiling will be dry wall.

All I want to do is to reduce the "boominess" of the bass and reduce the reflective "hollow" sound if I can without dulling the whole room.

My question is for the top 4' of the walls: is cork okay or should I do carpet panels or just leave the dry wall alone? Again, I'm not looking for perfection, just trying to reduce bass muddiness and mid range reflections with reasonable treatments. I just want to ensure I'm not missing something really obvious.

Thanks.


----------



## genesis_avs

HopefulFred said:


> It is true that the paper will reflect some of the signal, but that's probably not a problem. Any bass or even midrange signal has so much energy that the paper will not have enough mass to reflect it. Only high frequency sounds can be reflected by paper. The effect of that will likely be that the audible portion of the reflection acts to broaden the acoustic image from the front soundstage. If you are in a mixing environment - not a home theater - the focus of the soundstage is probably very important, and you should avoid the paper. In a home theater, it's mostly a matter of preference.


Using this logic/information, could you just use normal (non-AT) fabric to cover the panels and get the same results acoustically? Seems like it would be a win-win-win: save money by using less expensive fabric, reflect or diffuse the high frequencies to broaden image, and absorb the midrange. Am I missing something?


----------



## HopefulFred

I am unaware of any errors in your logic, but as with all things it will depend on your particular situation and goals. I'm not in a position to say.


----------



## audiovideoholic

double post


----------



## audiovideoholic

Has there been any advancement in Folded Well QRD type designs since this build linked from back some years ago? They look extremely easy to build but don't know if they can be modeled now or not with software. 

https://www.gearslutz.com/board/bas.../369164-diy-diffusors-max-12.html#post6061048

Any input for easy build designs like this or this design would be great. 

Thanks all


----------



## Roger Dressler

jeff43 said:


> Two sub's. All I want to do is to reduce the "boominess" of the bass and reduce the reflective "hollow" sound if I can without dulling the whole room.


Where are the subs positioned, and do either of them have EQ (either inside or via the AV processor)?


----------



## jeff43

Roger Dressler said:


> Where are the subs positioned, and do either of them have EQ (either inside or via the AV processor)?


I'll have one on the back wall, dead center, and one on the right wall also dead center. Both have crossover adjustments, I'll set at 50Hz due to my speakers, and my receiver auto sets volume via microphone. I think both have volume adjustments as well.


----------



## Roger Dressler

jeff43 said:


> I'll have one on the back wall, dead center, and one on the right wall also dead center. Both have crossover adjustments, I'll set at 50Hz due to my speakers, and my receiver auto sets volume via microphone. I think both have volume adjustments as well.


Ahh. So I take it that the system is not yet installed. Have you heard boominess in this room before? 

Besides auto level set, does the receiver have any built in equalization, like from Audyssey? Without some kind of EQ, there will be boominess. Having the subs on opposite walls can help that, though.


----------



## jeff43

Roger Dressler said:


> Ahh. So I take it that the system is not yet installed. Have you heard boominess in this room before?
> 
> Besides auto level set, does the receiver have any built in equalization, like from Audyssey? Without some kind of EQ, there will be boominess. Having the subs on opposite walls can help that, though.


Never mind the installed system, I haven't even built the room yet! I'm starting the first week of October, basement room 22'x12'x7' with staircase as one of the 12' walls (and open to other side). It's actually a simple build-out, have a good shot at being done by Christmas.

Anyway, I have had to deal with the "boominess" in my temp setup simply by turning down the volume level on the subwoofer. Depending which sound mode is chosen on this Sony AVR, it can be really bad. The AVR I'll be using is the Pioneer SC-85 which does have an equalizer. I get the crossover setting to match where the main speakers end and the volume adjustment to be just at the point of hearing the subwoofer but what do you focus on while using the equalizer on the subwoofer?


----------



## mhdiab

Has anyone used this:


Knauf ECOSE® Black Acoustical Board


http://www.knaufinsulation.us/en/content/black-acoustical-board


Specifically what I am wondering is the black outside. It is insulation so do you still wrap it or is it something people put up as is and it reduces glare as well as work as a acoustical board?

I found a few references using the search function but didn't see anyone discussing this part


My guess is that it helps just to not shine color through and you get some speaker cloth or similar from Jo-Anne and wrap it and that is the easy solution.

Pondering this vs Owens Corning and Guilford of Maine FR701


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## erwinfrombelgium

Interesting stuff, new to me. It's says that "The black surface provides a visual barrier with an aesthetic appearance, in both wall and ceiling applications." Hence you do not wrap it, as long as you apply these without the sides in sight (so wall-to-wall). Looks cool, but maybe not for formal living spaces. The heaviest and thickest quality is best of course.


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## nandkisham

*Riser Bass trap*

Please share thoughts/ Theory or experience on Riser bAss trap build.

Will be building a riser soon and would like to make it more functional for any bass trap use


----------



## healthnut

nandkisham said:


> Please share thoughts/ Theory or experience on Riser bAss trap build.
> 
> 
> 
> Will be building a riser soon and would like to make it more functional for any bass trap use




I did some research on this and in the end, decided it wasn't worth the trouble and expense, as always, YMMV


Sent from my iPhone using Tapatalk


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## pingas6

Hello everyone.

Excuse me .
I would like to use anthem (arc) by measurements of acoustic treatment put in my room, is it possible? or I have to use another way?
Thank you very much. 
Regards


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## grendelrt

Figured I would ask here first before making a new thread. If I am building a backer box for a ceiling speaker, I know the correct cubic feet volume, does it matter how close the back of the speaker is to the box as long as the volume is correct? For instance I only have 6.25 inches of room and the speaker is 5" deep, so it is only 1.25" of room behind the speaker but plenty of room on the sides.


----------



## climber07

grendelrt said:


> Figured I would ask here first before making a new thread. If I am building a backer box for a ceiling speaker, I know the correct cubic feet volume, does it matter how close the back of the speaker is to the box as long as the volume is correct? For instance I only have 6.25 inches of room and the speaker is 5" deep, so it is only 1.25" of room behind the speaker but plenty of room on the sides.


So long as the driver doesn't touch you're good to go.


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## grendelrt

climber07 said:


> So long as the driver doesn't touch you're good to go.


Awesome thanks!


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## ddigler

Can someone with experience tell me what the average HT treatment panel thickness is? 2"?

I don't have a budget to support a professional design for treatments in my new HT. just curious, can I get away with 1-2" thick panels?


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## BeerandBread

I NEED HELP ....

I have a separate wood outbuilding ...now insulated and it has a partially vaulted ceiling in the theater area and an open area opposite a solid wall.

I'm sure I should have some sound absorption on the wall and not sure about the slanted ceiling on the one side.


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## BeerandBread

pic update for last post indicates a wall height of 8 ft and a rise in ceiling of 4" in 12 " for 6 ft then a flat ceiling of 8 ft panel...at 9ft 6 inch high.

I don't have a wall for a reflection point on the one side.


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## climber07

ddigler said:


> Can someone with experience tell me what the average HT treatment panel thickness is? 2"?
> 
> I don't have a budget to support a professional design for treatments in my new HT. just curious, can I get away with 1-2" thick panels?


It depends entirely on the materials used. OC 703/705, Roxul Rockboard 60/80. It also depends on the frequencies you are looking to eliminate at reflection points. Most use 2" panels and are happy.


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## Horta

Hello friends

Quick question. My theater is getting built now. I will be using Quest Track to cover the acoustic panels with fabric myself. My question is, does anyone have the tools needed to do this job. The kit new is over $225 and a person only uses it once.

So do any of you all have it, that would like to sell it for a decent discount? Or have an affordable alternative? I know sounds silly we spend thousand for a room but then get cheep on a silly thing like a tool, but this project is already beyond expensive....

Jerry


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## BllDo

Horta said:


> Hello friends
> 
> Quick question. My theater is getting built now. I will be using Quest Track to cover the acoustic panels with fabric myself. My question is, does anyone have the tools needed to do this job. The kit new is over $225 and a person only uses it once.
> 
> So do any of you all have it, that would like to sell it for a decent discount? Or have an affordable alternative? I know sounds silly we spend thousand for a room but then get cheep on a silly thing like a tool, but this project is already beyond expensive....
> 
> Jerry


Not entirely sure what is in the Quest package, but you may be able to rent what you need here:
http://fabricmate.com/product/professional-contractor-tool-pack-returnable-version


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## asarose247

having designed and produced over 140 ft^2 clouds and assorted other corner panels, most 5+" thick, some only 3",

the best assembly "kit" I had was a pneumatic stapler, using 3/8" T-50's (iirc) for covering / fiber control applications,

and I still have my first empty box that used to have 5,000 staples in it,

must be the primitive way to go

this pic is 40 ft^2 for the 6 Scatmos tops,
2" 703 overlaid with 3" Roxul, a wooden frame on the top edges only so I had something to staple the fabric to .
the 703 provides the stiffness as a bottom layer

the ROI for my DIY, about $500 for all of it, metal, 2" 703, 3" roxul, bolts, spray paint, covering, etc

the 4 basic Unistrut pieces I had in "inventory" and were free, but still . . .

as compared to whatever this construct might have cost to have had it designed, built and installed

the empty frame is typical of my cloud frames for ceiling or reflection point5s. this frame in particular is going to have 6" roxul and the solid back is to block light as the 4 of these hang over my westward facing windows,

the objective is to have as much surface area open for what translates to mid/hi broad band absorption

the original suggestion wrt to a cloud for the Tops was 2 of 2 x 4 703 panels, but by the time I figured out to hold that up, the rest "just fell into place", that and a few hundred trips up and down the ladders with the tape measure.

and it won't help, but my WAF =0.

get inspired


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## jmh547

I posted this in the HT accessory forum and it was suggested I post here

I finally talked my wife into acoustic panels for the rear wall in my HT.

I really do not want to spend $100 ordering oc 705 or rockboard.

The two materials that are readily available in my area are 1.5" roxul comfort board and 3" safe and sound.

I do not think I can get away any thing deeper than 3" (WAF).

Would I be better off with a 3" deep box with 3" s&s or a 3" box with 1.5" comfortboard and a 1.5" gap between the insulation and wall?

Also my surround speakers have angled baffles and are mounted on the rear wall. The angled baffles cause the point towards the mlp but so some sound will hit the edge of the panel frame. Should I consider drilling large holes to reduce edge reflection?

Sent from my SM-G920V using Tapatalk


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## dnoonie

jmh547 said:


> Would I be better off with a 3" deep box with 3" s&s or a 3" box with 1.5" comfortboard and a 1.5" gap between the insulation and wall?
> 
> Also my surround speakers have angled baffles and are mounted on the rear wall. The angled baffles cause the point towards the mlp but so some sound will hit the edge of the panel frame. Should I consider drilling large holes to reduce edge reflection?


Go 3", unless you can go 4.5" or 6". If you need to double up the panels in the frame that works well.

It looks like the Comfort Board is 8lb per cube foot and the Safensound is 2.5lb per cube foot, use the Comfort board, unfaceed if possible and if you can't find 3" double up the sheets in the frame.
References:
http://www.roxul.com/files/RX-NA_EN...sidential/COMFORTBOARD80_TECHDATASHEET_EN.pdf
http://www.roxul.com/files/RX-NA_EN...d/Residential/SAFEnSOUND_TECHDATASHEET_EN.pdf

I'm not picturing the surround placement but slatted/open(ish) sides do absorb better if you want to router/jig saw/plunge cut them out. Check out how GIK frames look and you might get some ideas, http://www.gikacoustics.com/product/diy-bass-trap-acoustic-panel-frames/.

Cheers,


----------



## jmh547

@dnoonie thank you for the response. 


Going with 3" of material was my gut feel then I read a couple threads on spacing the material in the acoustic panels away from the wall. I believe this is more for bass absorption. 








Just for clarification I attached a picture of one of my surround speakers. As I said the front baffle is angled towards the MLP. This was done to allow me to better place the speaker vertically without out a big ugly bracket (WAF). Right now the woofer sits about 1" from the wall. I have plans to rebuild the boxes which will space the woofer roughly 2" from the wall. The panels will be placed between the two surround speakers with 3 feet from each speaker to the start of the panel.


----------



## JonasHansen

*Foam vs. mineral wool*

I am looking for some acoustic products which tame the reflections without absorbing them completely.

Two products I have looked at are Vicoustic Wavewood and GIK Alpha 2A. They are roughly the same depth but the main difference is, that Vicoustic use foam and GIK use mineral wool. I have found the absorbtion data for both. (See attachments)

When I compare the absorbtion numbers and look at the increase in percentage of GIK vs. Vicoustic, the percentage is quite large. (See the excel-screenshot attached) But take 100hz for example: 0,18 vs. 0,12 are both very small numbers so I am not sure how to interpret the results. 50% as an "absolute value" is large, but 50% of an insignificant value is not significant.

Vicoustic would be a lot easier/cheeper/better looking (IMO) than GIK, so they would be my preferred choice if performance is comparable. 

How would you interpret the difference?


----------



## dnoonie

JonasHansen said:


> I am looking for some acoustic products which tame the reflections without absorbing them completely.
> 
> Two products I have looked at are Vicoustic Wavewood and GIK Alpha 2A. They are roughly the same depth but the main difference is, that Vicoustic use foam and GIK use mineral wool. I have found the absorbtion data for both. (See attachments)
> 
> When I compare the absorbtion numbers and look at the increase in percentage of GIK vs. Vicoustic, the percentage is quite large. (See the excel-screenshot attached) But take 100hz for example: 0,18 vs. 0,12 are both very small numbers so I am not sure how to interpret the results. 50% as an "absolute value" is large, but 50% of an insignificant value is not significant.
> 
> Vicoustic would be a lot easier/cheeper/better looking (IMO) than GIK, so they would be my preferred choice if performance is comparable.
> 
> How would you interpret the difference?


Neither are intended to absorb bass, so anything below 200Hz isn't really applicable.

I've found that acoustic foam is simply not as effective at absorbing as rigid fiber board so I would expect the GIK to absorb better. I can see why you like the look, it looks cool to me too, is GIKs 2d (dot dash) 2A panel any more appealing to you vs. the 1d (slats)?

Here's a discussion in another forum, https://www.gearslutz.com/board/bas...am-etc/396568-vicoustic-wave-wood-panels.html*.

*Cheers,


----------



## myfipie

JonasHansen said:


> I am looking for some acoustic products which tame the reflections without absorbing them completely.
> 
> Two products I have looked at are Vicoustic Wavewood and GIK Alpha 2A. They are roughly the same depth but the main difference is, that Vicoustic use foam and GIK use mineral wool. I have found the absorbtion data for both. (See attachments)
> 
> When I compare the absorbtion numbers and look at the increase in percentage of GIK vs. Vicoustic, the percentage is quite large. (See the excel-screenshot attached) But take 100hz for example: 0,18 vs. 0,12 are both very small numbers so I am not sure how to interpret the results. 50% as an "absolute value" is large, but 50% of an insignificant value is not significant.
> 
> Vicoustic would be a lot easier/cheeper/better looking (IMO) than GIK, so they would be my preferred choice if performance is comparable.
> 
> How would you interpret the difference?


We use rigid fiberglass AND we did a lot of testing on the cuts to make sure we had a nice balance of absorption vs diffusion/scattering/reflection on the upper frequencies. If you are looking for more low end control then I would go with the Alpha 4A or 6A for panels. Keep in mind that these are binary cuts and come either 1D or 2D. 
http://www.gikacoustics.com/product/4a-alpha-panel-diffusor-acoustic-panel-bass-trap/
http://www.gikacoustics.com/product/6a-alpha-panel-diffusor-absorber/


----------



## John Budny

*Acoustic Panels*

I'm nearing completion of my media room and am looking to put some resources into taming the echos and boomy bass the room is producing. 

I did most of the work myself on the room, however at this point I want to forgo another DIY project and get to enjoying the room. I am therefore looking to purchase pre made panels/bass traps vs making my own unless there is a compelling argument against this. I am looking for thoughts and suggestions on how best to treat this space and online vendors I can purchase premade panels from. 

My initial thoughts were bass traps in the front two corners then some panels at the first reflection points on the side walls at the front of the room. Anything else "essential" for a starting point? 

I've looked briefly at GIK Acoustics, however their panels are quite thick at 4" and I was hoping for a less intrusive solution. Acoustical Solutions has 1" and 2" panels and gives a NRC (noise reduction rating) for their panels that looks good. Although to be honest, I have no idea if NRC is a universal measurement for acoustic treatments or just marketing jargon aimed at getting acoustically challenged buyers like me to bite the hook. 

Will panels and bass traps from the various vendors perform similar to one another even though they might use different materials? 

Thanks for the help.

Room basics:

Length 19.5'
Width 13' 10"
Ceiling 7' 5"
Half of back wall is open to a hallway/stairs
There will be crown molding that has yet to be installed, it will extend about 6" down from ceiling
11 speakers (7.2.4)
110" screen on front wall that is approximately 8' wide
Only furniture in the room is currently a futon, will later be replaced with a single row of 4 cinema seats
No other furniture in the room other than a ceiling mounted projector at the back of the room


----------



## sdurani

John Budny said:


> I've looked briefly at GIK Acoustics, however their panels are quite thick at 4" and I was hoping for a less intrusive solution.


I would stick with the 4" panels for broadband absorption (you don't want the panels to inadvertently become a form of tone control by only absorbing the mid-to-high frequencies). I'd first add absorption on the front wall, to prevent reflections from that direction muddying up the front soundstage. On the side wall, I would start by absorbing contra-lateral reflections (where the left speaker reflects on right wall and vice versa). On the back wall, place absorption behind the right rear speaker to mimic the lack of wall behind the left rear speaker (restore symmetry).


----------



## zvipster

jmh547 said:


> @dnoonie thank you for the response.
> 
> 
> Going with 3" of material was my gut feel then I read a couple threads on spacing the material in the acoustic panels away from the wall. I believe this is more for bass absorption.
> 
> 
> 
> 
> 
> 
> 
> 
> Just for clarification I attached a picture of one of my surround speakers. As I said the front baffle is angled towards the MLP. This was done to allow me to better place the speaker vertically without out a big ugly bracket (WAF). Right now the woofer sits about 1" from the wall. I have plans to rebuild the boxes which will space the woofer roughly 2" from the wall. The panels will be placed between the two surround speakers with 3 feet from each speaker to the start of the panel.


You are correct about spacing makes it absorb lower frequencies - what you are missing though is that that is only true if you use the SAME thickness of a panel.
Lets say a 4" panel - theoretically it would be able to absorb down to 857Hz, but by moving the panel away from the wall the same distance as the thickness of the panel, then you will be able to absorb down half as low = 428,75Hz.
Keep in mind the is theoretical numbers and the absorbtion usually goes another to two octaves lower before being negligable.
Hope this helped?


----------



## Roger Dressler

JonasHansen said:


> How would you interpret the difference?


My thinking is that the key aspect of these types of hybrid devices is the fall off of absorption above the peak. That's what the wood layer brings to the party. In that respect they look very similar. 

GIK is fiberglass, not mineral wool, but no matter, the main difference is the acoustic foam in Vicoustic as you noted. They use that in many of their products. It does appear to have slightly less bass absorption than a similar thickness of fiberglass, but the bass performance can be increased by either spacing the panel away from the wall an inch or 2, or by adding more absorber behind, which will not alter the upper frequency characteristic. The stuff you add behind can be cheap and ugly, as it won't be seen.


----------



## Roger Dressler

zvipster said:


> You are correct about spacing makes it absorb lower frequencies - what you are missing though is that that is only true if you use the SAME thickness of a panel.


I do not believe that is true. The spacing can be different than the absorber thickness and still make an improvement. But it is not the same as thicker material.


----------



## zvipster

Roger Dressler said:


> I do not believe that is true. The spacing can be different than the absorber thickness and still make an improvement. But it is not the same as thicker material.


Well it is 
A 1" board spaced 1" from the wall is not as good as a 2" board directly on the wall.

To be more precise - what I meant was that yes, it does absorb more bass if spaced, but only more if we are talking the same board thickness. 
Like you can't take a 1" board and mount it 3" from the wall and get the same result as a 4" board directly on the wall - the 4" would absorb better at lower freq's.
Sorry if that was not clear enough.


----------



## Roger Dressler

zvipster said:


> Well it is
> A 1" board spaced 1" from the wall is not as good as a 2" board directly on the wall.
> 
> Like you can't take a 1" board and mount it 3" from the wall and get the same result as a 4" board directly on the wall - the 4" would absorb better at lower freq's.


Of course. But no one asserted that would be the case. I was just mentioning the spacing did not have to be the same dimension as the material thickness in order to yield a benefit. The data supports that. If you have data to the contrary, happy to see it. 



> To be more precise - what I meant was that yes, it does absorb more bass if spaced, *but only more if we are talking the same board thickness.*


----------



## sdurani

zvipster said:


> You are correct about spacing makes it absorb lower frequencies - what you are missing though is that that is *only true if* you use the SAME thickness of a panel.


No, the thickness of the panel and the thickness of the air gap have nothing to do with each other.


> Lets say a 4" panel - theoretically it would be able to absorb down to 857Hz, but by moving the panel away from the wall the same distance as the thickness of the panel, then you will be able to absorb down half as low = 428,75Hz.


The second of the two graphs that Roger posted indicates that your claim is not true; i.e., moving a 1" panel 1" from the wall did not make it "able to absorb down half as low" compared to the same 1" panel on the wall.


----------



## zvipster

sdurani said:


> No, the thickness of the panel and the thickness of the air gap have nothing to do with each other. The second of the two graphs that Roger posted indicates that your claim is not true; i.e., moving a 1" panel 1" from the wall did not make it "able to absorb down half as low" compared to the same 1" panel on the wall.


Well, the a graph can tell what it wants to tell - but physics are physics and they don't care.
The way a resistive absorbtion panel works is through the means of converting sound energy into heat. This is most effectively done at 1/4 length of a given soundwave - why? Because here the speed of the sound wave is highest. Thus it is simple to assert the lower effective lower limit of a panel will be half. This does not translate 100% to the real world, but thats the theory behind if the panel has the right density.




Roger Dressler said:


> Of course. But no one asserted that would be the case. I was just mentioning the spacing did not have to be the same dimension as the material thickness in order to yield a benefit. The data supports that. If you have data to the contrary, happy to see it.


Ok true - it's just where it will be the most effective.


----------



## sdurani

zvipster said:


> Well, the a graph can tell what it wants to tell - but physics are physics and they don't care.


If you're now claiming that those graphs aren't showing physics, then can you post measurements that support your earlier claim that _"spacing makes it absorb lower frequencies ... __is *only true if* you use the SAME thickness of a panel"_? Any evidence to show that the air gap must be the same as panel thickness in order to absorb lower frequencies?


> Thus it is simple to assert the lower effective lower limit of a panel will be half. This does not translate 100% to the real world, but thats the theory behind if the panel has the right density.


What is the right density to make that happen?


----------



## zvipster

sdurani said:


> If you're now claiming that those graphs aren't showing physics, then can you post measurements that support your earlier claim that _"spacing makes it absorb lower frequencies ... __is *only true if* you use the SAME thickness of a panel"_? Any evidence to show that the air gap must be the same as panel thickness in order to absorb lower frequencies? What is the right density to make that happen?


Ahhh, I will just stop now.
It's not easy when English not my native language.
Never claimed it would not work if the spacings not the same - just said that that's where it's most effective.


----------



## Red.Blue

I already have raised channel on my ceiling with insulation above but I'm not happy with the noise isolation from the upstairs adjacent space. Mostly noticing "vibration" type of intrusion from footsteps, doors, etc. Not a lot but I want to try and correct. If I do stretched fabric panels on the ceiling with absorbtive material beind it, will it help or am I just wasting money? What would be the best material or specific product to deaden these outside sounds (but then am I created a new problem of my room being too absorbtive)?


----------



## dchalfont

I ordered bass traps that are considered heresy by acoustic treatment buffs but I had bo choice as my room is small and my budget is low, even if I had $10k for panels I simply couldn't fit the like of realtraps or diy panels in.

The panels say they are effective down to 70hZ and they are cut off at an angle at the back for an air gap.

They are foam bass traps but are 53cm across the face and 37.cm along each wall.

I know foam isn't the best solution but it's not like I bought that terrible 1ftx1ftx1ft corner sections that you can buy 40 pieces of for like $50. I paid $830 for enough for the 4 vertical corners and am going to add 60cmx60cm 3 inch thick foam panels to the roof, rear wall, front wall behind the front speakers and to the side of the centre speaker before finally getting 3 more bass traps for the front and rear wall/roof corners.


----------



## asarose247

FYI 
http://www.buyinsulationproductstore.com/


6, standard 2' x 4',pack of 2" 703 for much less, say $20-25+ , depending on shipping zip code, (my purchase -$89)

slightly more attractive price,


----------



## rboster

I contacted the company I bought the panels from, but I thought I would ask here too.

I have some diffusion panels made from expanded polystyrene. I know that one can use water based paint without any neg. acoustical impact. I've been trying to find some water based spray paint. Krylon looks like they may have stopped producing their H2o spray paint...but to be honest, some of the user reviews were less than stellar. 

I've never used a paint sprayer, so I'm nervous about the results. I prefer to use spray paint, since it's easier and I think the panels will look more professional vs brushing paint on them. That being said, anyone have any suggestions for paint brands, techniques or tools to use for the best results?

Ron

PS: I did a search of the thread using "paint" as my search word and didn't find any direct answers.


----------



## asarose247

^
could you post a picture and source info

spraying latex can be tricky, it usually needs extra thinning

HF could provide an inexpensive gravity feed sprayer, if you have the air compressor,

depending on the topology of the diffuser and the depth and variety of angles, 

patience and multiple light coats wrt various angles, etc. should gittter done


----------



## dnoonie

^^
Great topic!

I'm considering GIK gridfusors above my MLP and I'm struggling with how to "finish" them. Paint them and attach them to the ceiling or frame them, cover them and hang them. I saved some EPS packing material to experiment with for painting, it's not a high priority project right now but the I'm really interested in how things go with the EPS painting.

Cheers,


----------



## robc1976

dnoonie said:


> ^^
> Great topic!
> 
> I'm considering GIK gridfusors above my MLP and I'm struggling with how to "finish" them. Paint them and attach them to the ceiling or frame them, cover them and hang them. I saved some EPS packing material to experiment with for painting, it's not a high priority project right now but the I'm really interested in how things go with the EPS painting.
> 
> Cheers,


love GIK products, my entire room is done in GIK. BPAPE at GIK suggested 244 panels on reflection points above MLP instead of diffusion


----------



## dnoonie

robc1976 said:


> love GIK products, my entire room is done in GIK. BPAPE at GIK suggested 244 panels on reflection points above MLP instead of diffusion


I've got 3" with 3"tapering to 2" air gap at overhead first reflection points. I'm looking at above the MLP.

Quote from http://www.gikacoustics.com/diffusion-by-jeff-hedback/
"TABOO TOPIC…diffusion above mix position. Yes it’s true and is now in print for others to read. I have successfully applied QRD style diffusors above mix position and increased the ability to determine spatial and depth decisions…lock in on attack/release compressor settings, combine reverb and panning elements. It is not a “one size fits all” application BUT it can work especially if the mix engineer has a greater sensitivity to vertical reflections."

Cheers,


----------



## rboster

asarose247 said:


> ^
> could you post a picture and source info
> 
> spraying latex can be tricky, it usually needs extra thinning
> 
> HF could provide an inexpensive gravity feed sprayer, if you have the air compressor,
> 
> depending on the topology of the diffuser and the depth and variety of angles,
> 
> patience and multiple light coats wrt various angles, etc. should gittter done





dnoonie said:


> ^^
> Great topic!
> 
> I'm considering GIK gridfusors above my MLP and I'm struggling with how to "finish" them. Paint them and attach them to the ceiling or frame them, cover them and hang them. I saved some EPS packing material to experiment with for painting, it's not a high priority project right now but the I'm really interested in how things go with the EPS painting.
> 
> Cheers,


It the product that dnoonie is talking about

http://www.gikacoustics.com/product/gik-acoustics-gridfusor/

I do have an air compressor, so that's a start.


----------



## robc1976

dnoonie said:


> I've got 3" with 3"tapering to 2" air gap at overhead first reflection points. I'm looking at above the MLP.
> 
> Quote from http://www.gikacoustics.com/diffusion-by-jeff-hedback/
> "TABOO TOPIC…diffusion above mix position. Yes it’s true and is now in print for others to read. I have successfully applied QRD style diffusors above mix position and increased the ability to determine spatial and depth decisions…lock in on attack/release compressor settings, combine reverb and panning elements. It is not a “one size fits all” application BUT it can work especially if the mix engineer has a greater sensitivity to vertical reflections."
> 
> Cheers,


okay gotcha, you just want a bit more diffusion, do your panels have there "scatter plates" in them? Wanted a opinion from somone who has them. Upgrading the color ava getting new panels and considering adding the scatterer plates.


----------



## asarose247

@rboster

i took a long look wrt the link
my extensive experience as a professional painter, tho not recently, makes me think of a few things

there is undoubtedly a finish on that wood, almost doesn't matter what type, it's going to cause major, for me almost a non started, time consuming adhesion headaches unless your prep everywhere - sand everything and evereywhere and have the patience of , who ever . .to spray slowly and softly and let dry between coats 

there are plans around the internet to build diffusers that would let you pre-color/finish as you wish, but that is a subject for another time.

so, for my nickel and given the considerable expense 
assuming you want to color them to more aesthetically blend them into the decor and/or be mostly invisible ,
I'd find a proper/ suitable AT material for the job and cover them, staple around to the back, or make a sock.

that way if you change decor or whatever, you can "just" change the material to suit

personally, if i could afford that stuff, tho I'm sure i could build them, but if i were to pay, I'd ask the 
gik folks to do the painting of whatever for me. you can call me lazy . . .

HTH


----------



## Lesmor

AFAIK those GIK gridfusers should only be painted with a water based emulsion


----------



## Lesmor

Anyway
I have 6 x GIK 242 panels above the MLP and still don't think I am capturing all the L/C/R reflections so was considering adding some 2'x2' skyline ESP diffusers.

Would this be a good move or should I just add more 242 absorbers

The ceiling is 20 'x 17'6"


----------



## robc1976

Lesmor said:


> Anyway
> I have 6 x GIK 242 panels above the MLP and still don't think I am capturing all the L/C/R reflections so was considering adding some 2'x2' skyline ESP diffusers.
> 
> Would this be a good move or should I just add more 242 absorbers
> 
> The ceiling is 20 'x 17'6"


I had 242 also, go to 244 (thinker) made a huge difference, I have a lot of reflections due to fronts and wides


----------



## Lesmor

robc1976 said:


> I had 242 also, go to 244 (thinker) made a huge difference, I have a lot of reflections due to fronts and wides


Yes I did make a mistake in not using 244's instead 
One concern was/is perhaps blocking or having a shadow from the image from my projector


----------



## robc1976

Lesmor said:


> Yes I did make a mistake in not using 244's instead
> One concern was/is perhaps blocking or having a shadow from the image from my projector


I did the same lol


----------



## dnoonie

robc1976 said:


> okay gotcha, you just want a bit more diffusion, do your panels have there "scatter plates" in them? Wanted a opinion from somone who has them. Upgrading the color ava getting new panels and considering adding the scatterer plates.


I've not used the gik with scatter plate before. I would guess that in the right place they'd sound great. Seattle's EMP JBL theater has scattering over absorption and it sounds great as long as you're not seated too close to the walls, not that it sounds bad just not as good as 12" away from the walls.



asarose247 said:


> @*rboster*
> 
> so, for my nickel and given the considerable expense
> assuming you want to color them to more aesthetically blend them into the decor and/or be mostly invisible ,
> I'd find a proper/ suitable AT material for the job and cover them, staple around to the back, *or make a sock.*
> 
> that way if you change decor or whatever, you can "just" change the material to suit
> 
> HTH


The sock idea is an interesting one.

Below are pics from a project I struggled with. They're the Auralux Mini fusor. I couldn't get paint to stick to them so I mounted them to 1/4" MDF and covered them with AT fabric.
They will pop off the MDF if handled roughly. It’s best to back filled them with acoustic foam. When gluing be sure to *leave a section *(a half inch works well) *with no glue *otherwise the sealed air pocket will cause the diffuser to pop off a lot easier.

I stapled the acoustic fabric to the MDF, quick and easy, with a hand powered staple gun. Notice the wavy edge on the speaker grill cloth? It’s best to use pinking sheers on your speaker cloth. I stretched the fabric like crazy to get it to look smooth on the front, it's really tough fabric!

I don't think the EPS would hold up to the force exerted on the thing to stretch fabric over it AND attach it to the EPS material, that's why I was considering framing them. The problem with framing them is it raises the cost considerably. The sock idea might work though but would require some sowing expertise or...there are fabric glues now that work real good. Why not just use wood QRDs then? Weight, I don't want to hang that much weight, I can hang 4"x2'x4' panels from the ceiling by myself, but a 45lb wood QRD I can't, plus it complicates rigging, I'd want to use metal clips for attaching something that heavy.


Cheers,


----------



## rboster

@dnoonie. Those look great. Attaching to the board and the fabrics stretch as the other member suggested(too) look very professional. 

Ron


----------



## dnoonie

Double post deleted.


----------



## dnoonie

rboster said:


> @*dnoonie* . Those look great. Attaching to the board and the fabrics stretch as the other member suggested(too) look very professional.
> 
> Ron


Thanks! Yes fabric can cover a lot of flaws, I wasn't about to strip the paint off those things and start over...

My preliminary plan:
1 Try to paint the EPS packing material I have.
2 If it paints fine then
a. Paint a couple GridFusors and see how they look.
b. If ugly, figure out how to cover them
Options for covering:
EPS won't hold up to rough treatment like tightly stretched fabric and staples. So 
1. Test fabric glue on EPS packing material
If it works, try stretching fabric over GridFusor and gluing to it's back
If that sounds like too much trouble, or starts to break the GridFusor then break down and just buy 6" pre-made bass trap frames and put the GridFusors inside and cover with AT fabric.

I'm not sure this helps. It's only part way thought out so I'm sure there are flaws in my logic somewhere. Honestly after thinking through it this much I'm leaning toward framing and covering with cloth. In which case I'd order the GridFusors, see how wide the edge is and if it will fit inside a pre-made 6" bass trap frame after removing the edge then order up some 6" bass trap frames, if not then make my own frames. Another option would be to see if GIK would frame and cover them. I calculated that it would cost $205 each for a 2' x 4' framed and covered GridFusor including all shipping.

I'm interested to know what you end up doing, check back when you get a chance.

Cheers,


----------



## Lesmor

dnoonie said:


> Thanks! Yes fabric can cover a lot of flaws, I wasn't about to strip the paint off those things and start over...
> 
> My preliminary plan:
> 1 Try to paint the EPS packing material I have.
> 2 If it paints fine then
> a. Paint a couple GridFusors and see how they look.
> b. If ugly, figure out how to cover them
> Options for covering:
> EPS won't hold up to rough treatment like tightly stretched fabric and staples. So
> 1. Test fabric glue on EPS packing material
> If it works, try stretching fabric over GridFusor and gluing to it's back
> If that sounds like too much trouble, or starts to break the GridFusor then break down and just buy 6" pre-made bass trap frames and put the GridFusors inside and cover with AT fabric.
> 
> I'm not sure this helps. It's only part way thought out so I'm sure there are flaws in my logic somewhere. Honestly after thinking through it this much I'm leaning toward framing and covering with cloth. In which case I'd order the GridFusors, see how wide the edge is and if it will fit inside a pre-made 6" bass trap frame after removing the edge then order up some 6" bass trap frames, if not then make my own frames. Another option would be to see if GIK would frame and cover them. I calculated that it would cost $205 each for a 2' x 4' framed and covered GridFusor including all shipping.
> 
> I'm interested to know what you end up doing, check back when you get a chance.
> 
> Cheers,


GIK Europe can also supply a product called versifuser which looks like the equivelent to the gridfuser, They also suply it mounted in a frame covered with cloth calling it a flexfusor
http://gikacoustics.co.uk/product/gik-acoustics-flexfusor-diffusor/

I imagine this would also be available in the US


----------



## rboster

One update I forgot to share is the use of the 3M Dual Lock reclosable fastener. I painted the edges of the slightly small piece of sanded plywood and mounted it to the wall with a wood screw (already had the hole from previous speaker mount). I place a piece in each corner of the board and corresponding piece to the skyline diffuser panel. Let the adhesive dry for 24 hours. The fasteners lock into place with a very secure hold. I'll have to pry them of the plywood to remove. Down side is the panels have the fasteners secure to the diffuser. I'm sure if I try to remove them it would damage the backside of the panel. But, there is now only one small hole wood screw size hole in the wall to repair and repair if I remove the panels. 

https://www.amazon.com/3M-Dual-Lock...07OXK1AK/ref=cm_cr_arp_d_product_sims?ie=UTF8

BTW, they sell this product at walmart, target etc. You don't have to buy the industrial size roll that I linked to at amazon...just too lazy to link an example besides the first one that came up on google.


----------



## dnoonie

Lesmor said:


> GIK Europe can also supply a product called versifuser which looks like the equivelent to the gridfuser, They also suply it mounted in a frame covered with cloth calling it a flexfusor
> http://gikacoustics.co.uk/product/gik-acoustics-flexfusor-diffusor/
> 
> I imagine this would also be available in the US


That looks like the exact product I'm looking for! And at 4.1kg it would be super easy for me to ceiling mount by myself. Thanks! Although it's not available in the US I'm sure if I call they can work something out.

I've got a couple other projects to do before I get to that one. I want to put Polyfusors on the back wall and back horizontal corners. I also need to complete an entry hall project that was started awhile back. I might do the Polyfusor and Flexfusor project at the same time if I have the money but it might not happen before the end of the year.



rboster said:


> One update I forgot to share is the use of the 3M Dual Lock reclosable fastener.


I like that type of product and have used it for things in the past. Other methods of attachment, picture hooks, z-clips (also known as french cleat), T-pins, hooks with eyes, hooks or eyes with nylon ties. I've also considered carabiners for more robust attachment (I'd consider these or steel re-closable loop for hanging a wood QRD from a ceiling with two eyes). Having a 50yo house with wavy walls and ceilings limits the type of attachments I can use. 

I also usually mount to a mounting strip anchored to studs rather than directly to the wall (like in the picture below). It minimizes damage, provides a more secure mounting surface and provides an even mounting surface than can span windows.

Cheers,


----------



## Lesmor

So any thoughts on ESP Skyline on the ceiling?
As sound won't be hitting them at 90 deg as it would on the rear wall I am concerned they might be wasted.

Or should I add GIK 244's to my existing 242's instead?


----------



## dnoonie

Lesmor said:


> So any thoughts on ESP Skyline on the ceiling?
> As sound won't be hitting them at 90 deg as it would on the rear wall I am concerned they might be wasted.
> 
> Or should I add GIK 244's to my existing 242's instead?


Do you have surround speakers beside the MLP? I think Skyline would be better. Do you have speakers only toward the back and front? I think something like the GIK Gridfusor we've been talking about would be better.

Cheers,


----------



## Lesmor

dnoonie said:


> Do you have surround speakers beside the MLP? I think Skyline would be better. Do you have speakers only toward the back and front? I think something like the GIK Gridfusor we've been talking about would be better.
> 
> Cheers,


Hi dnoonie
Thanks for the reply

I use a 7.1.4 setup (4 wall mounted height speakers for Atmos) in a dedicated room.

I have a total of 38 panels.
Some are DIY, some GIK and 3 are are RPG QRD7's in a rear wall array
All available corners have floor to ceiling GIK Tri-traps.

Although I have 6 ceiling mounted GIK 242 above the MLP I dont think they are catching all of the main speaker reflections plus there is still a lot of bare drywall on the 20' x 17'6"ceiling


----------



## Mashie Saldana

I'm currently building a soffit that will be used as a bass trap around the room, it is 24" wide and 12" tall. What is the most suitable density rockwool insulation to use for stuffing? I was thinking of 3.0pcf but maybe I should go for something with even less density?

Also for the panels covering the first reflection points on the walls, should I go with 4" of 3.0, 4.5 or 6.0pcf rockwool?


----------



## rboster

Lesmor said:


> Hi dnoonie
> Thanks for the reply
> 
> I use a 7.1.4 setup (4 wall mounted height speakers for Atmos) in a dedicated room.
> 
> I have a total of 38 panels.
> Some are DIY, some GIK and 3 are are RPG QRD7's in a rear wall array
> All available corners have floor to ceiling GIK Tri-traps.
> 
> Although I have 6 ceiling mounted GIK 242 above the MLP I dont think they are catching all of the main speaker reflections plus there is still a lot of bare drywall on the 20' x 17'6"ceiling


I would love to see some pics of your room.


----------



## Lesmor

rboster said:


> I would love to see some pics of your room.


The room is not without issues with a alcove at the front right, a bay window centered at the left sidewall and a small glass panel to the right of and slightly behind the MLP.
Compared to some rooms I have seen it couldn't really be classed as a theater as such but its great to have the dedicated space.

If it wasn't considered to be off thread I could certainly post some pics.

Andy


----------



## rboster

Lesmor said:


> The room is not without issues with a alcove at the front right, a bay window centered at the left sidewall and a small glass panel to the right of and slightly behind the MLP.
> Compared to some rooms I have seen it couldn't really be classed as a theater as such but its great to have the dedicated space.
> 
> If it wasn't considered to be off thread I could certainly post some pics.
> 
> Andy


Thanks Andy. I'm interested in seeing acoustic treatments and their placements etc. Even though each room is different, I like to get a feel for what others have done both from a performance and aesthetic perspective. If it's a pain, no need....I completely understand. 

Ron


----------



## Lesmor

rboster said:


> Thanks Andy. I'm interested in seeing acoustic treatments and their placements etc. Even though each room is different, I like to get a feel for what others have done both from a performance and aesthetic perspective. If it's a pain, no need....I completely understand.
> 
> Ron


Its no problem


----------



## rboster

Lesmor said:


> Its no problem


Looks great. Thanks for sharing the pics. I was particular interested in the diffusion placement. 

Thanks again
ron


----------



## audiovideoholic

Mashie Saldana said:


> I'm currently building a soffit that will be used as a bass trap around the room, it is 24" wide and 12" tall. What is the most suitable density rockwool insulation to use for stuffing? I was thinking of 3.0pcf but maybe I should go for something with even less density?
> 
> Also for the panels covering the first reflection points on the walls, should I go with 4" of 3.0, 4.5 or 6.0pcf rockwool?


Care to elaborate on this design and how it will work? 

If it's of any value I was told to fill mine with R30 by my designer and then place linacoustic on the underside around the entire perimeter covered by fabric.


----------



## Mashie Saldana

audiovideoholic said:


> Care to elaborate on this design and how it will work?
> 
> If it's of any value I was told to fill mine with R30 by my designer and then place linacoustic on the underside around the entire perimeter covered by fabric.


Due to the shape of my room I can't really do wall-wall corner traps due to windows. So instead the plan is to do wall-ceiling corner traps as part of a soffit 2ft wide, 1ft tall along three of the walls. Instead of using plasterboard as per typical soffit design I will build fabric panels for the bottom and front. The inside will be filled with insulation and nothing else as we don't use HVAC here.

I will not cover all walls with treatments, mainly the main reflection points with broadband absorbers.


----------



## austin85

Hey everyone. I am in the process of building out my theater room and having a blast so far. I come to you all for room treatment advice! I’ve been in touch with Bryan from GIK Acoustics and receiving some great advice as well. We’ve discussed options, but I’m looking for a bit more conversation regarding pros/cons of diffusion and absorption products, as GIK sells many types based on one’s needs. First, some background information.

*Room Dimensions*

__
https://flic.kr/p/30480941161
​
The decibel measurements noted in the diagram were performed with pink noise running only through my subwoofer


----------



## danielrg

I have much to do to treat my currently untreated room.

But first, one question. 

I have a 7.1 system. 

When I go through my speakers on the AVR 1 by 1 (the level setting mode of Audyssey) with the pink noise or whatever it is, when either of the rear speakers are on, I actually hear it louder from the screen than from the rear of me.

I figure that can't be good. Shouldn't rear speakers sound like they are behind me?

I don't have an acoustically transparent (AT) screen. My screen covers 70% of the screen wall. So I don't see how to treat the front wall - it sounds like the rear speakers are just bouncing off the front screen.

I'm hoping this is a question the answers of which can teach me something good or cool from the smart experienced people.

Thanks in advance! My signature has my build thread if you're interested in all the details of my room.


----------



## TheNecromancer

I'm building a small HT. 12 x 18. Basic cookie cutter build. I have a roll of 1" Linacoustic RC which I have planned to use 2" thick on the front wall. Just found a couple of cases of 1" cotton panels that can be had cheap. 

So is there any real advantage to cotton over Linacoustic? Which would you choose?


----------



## Mfusick

Treating bass is a different thing than treating the higher frequencies (specifically managing dialogue intelligibility, or focus vs envelopment). Keep them separate from each other because you should have different goals for each.


----------



## Blackdevil77

Does GIK Acoustic ever have a sale, free shipping or any promotions like that? I have a bunch of their panels and want to add some bass traps and diffusion. The cost added up to crazy amounts rather quickly. I just bought a new processor for the home theater as well, if I drop a bunch of money on acoustic treatments now, I'll have my testicles confiscated.


----------



## sdurani

Blackdevil77 said:


> I have a bunch of their panels and want to add some bass traps and diffusion. The cost added up to crazy amounts rather quickly.


What acoustical problem are you trying to fix?


----------



## Blackdevil77

sdurani said:


> What acoustical problem are you trying to fix?


Currently my room only has a few absorption panels. I have no corner bass traps or any diffusion of any kind. The sound in my room is good, WITH Audyssey XT32 engaged. With XT32 disengaged, the sound is drastically different. This makes me think the room correction software had to go crazy with the EQ to flatten out the in room response. I want to try to flatten out the response a bit through room treatments so the room correction doesn't have to drastically adjust the EQ to flatten things out.


----------



## sdurani

Blackdevil77 said:


> I want to try to flatten out the response a bit through room treatments so the room correction doesn't have to drastically adjust the EQ to flatten things out.


Always a good idea. But treatments aren't going to be much help in the subwoofer range, where you have the largest peaks & dips, especially compared to placement (subwoofers and seating). The other benefit of placement is that it is free (doesn't cost anything to move a sub). 

So, first choice to smoothen (not necessarily flatten) the response should be placement. What placement alone can't fix, try to address with treatments. What placement & treatments can't fix, finish off with EQ. 

Do you have any measurements showing where the peaks & dips are?


----------



## Blackdevil77

sdurani said:


> Always a good idea. But treatments aren't going to be much help in the subwoofer range, where you have the largest peaks & dips, especially compared to placement (subwoofers and seating). The other benefit of placement is that it is free (doesn't cost anything to move a sub).
> 
> So, first choice to smoothen (not necessarily flatten) the response should be placement. What placement alone can't fix, try to address with treatments. What placement & treatments can't fix, finish off with EQ.
> 
> Do you have any measurements showing where the peaks & dips are?


I am gonna try to experiment with sub placement, I'm currently waiting for a pair of speaker stands for my Seaton Cat 12C's, right now they are on my subs (2 Seaton SubM HP's). 

No measurements yet, I'm about to order a miniDSP 2X4 HD with the UMIK1. Once the mic comes, I can take some measurements with REW.


----------



## robc1976

Lesmor said:


> Hi dnoonie
> Thanks for the reply
> 
> I use a 7.1.4 setup (4 wall mounted height speakers for Atmos) in a dedicated room.
> 
> I have a total of 38 panels.
> Some are DIY, some GIK and 3 are are RPG QRD7's in a rear wall array
> All available corners have floor to ceiling GIK Tri-traps.
> 
> Although I have 6 ceiling mounted GIK 242 above the MLP I dont think they are catching all of the main speaker reflections plus there is still a lot of bare drywall on the 20' x 17'6"ceiling


38 panels? ! I thought I had a lot lol! 

I have 9.2 system with 20 panels, floor to ceiling tritraps and qrd and monster traps on rear wall. Love GIK! 

I am actually adding 2nd row of seating so will get 7 more panels but am replacing all panels with different color and scatter plates in the panels. Have decided to go with 244 on ceiling and leave 242 on side walls.


----------



## Lesmor

robc1976 said:


> 38 panels? ! I thought I had a lot lol!
> 
> I have 9.2 system with 20 panels, floor to ceiling tritraps and qrd and monster traps on rear wall. Love GIK!
> 
> I am actually adding 2nd row of seating so will get 7 more panels but am replacing all panels with different color and scatter plates in the panels. Have decided to go with 244 on ceiling and leave 242 on side walls.


Thinking about it I should have been more specific as its 30 panels and Floor to ceiling tri-traps (8 x 4')

If doing it again or adding more I would also do what you are suggesting and go for scatter plates and 244's on the ceiling


----------



## robc1976

Lesmor said:


> Thinking about it I should have been more specific as its 30 panels and Floor to ceiling tri-traps (8 x 4')
> 
> If doing it again or adding more I would also do what you are suggesting and go for scatter plates and 244's on the ceiling


I bet your room is awesome


----------



## Lesmor

robc1976 said:


> I bet your room is awesome


As I imagine your would be too.
I'm very happy that I went for room treatments,the cost does mount up but no regrets.


----------



## robc1976

Lesmor said:


> As I imagine your would be too.
> I'm very happy that I went for room treatments,the cost does mount up but no regrets.


it does as well, I think the worst part of treatments is pinpointing reflection points lol! That and hanging panels on the ceiling lol


----------



## dnoonie

Now would be a good time to order from http://www.acoustimac.com/.

Things to consider before ordering:


No diffusion (no scatter plates or combo diffusion products)
If you plan on getting products from another company get a fabric that matches, most folks have Guilford of Maine fabric.
Their room kits are a good deal but have a lot of 2" panels, they're great for getting started but I've ended up swapping 2" for 4" panels in places as well as diffusion for 2".
Consider how what you order might get used or re-purposed.

Cheers,


----------



## robc1976

dnoonie said:


> Now would be a good time to order from http://www.acoustimac.com/.
> 
> Things to consider before ordering:
> 
> 
> No diffusion (no scatter plates or combo diffusion products)
> If you plan on getting products from another company get a fabric that matches, most folks have Guilford of Maine fabric.
> Their room kits are a good deal but have a lot of 2" panels, they're great for getting started but I've ended up swapping 2" for 4" panels in places as well as diffusion for 2".
> Consider how what you order might get used or re-purposed.
> 
> Cheers,


 totally 100% true.

Also, some companies advertise a 3" panel but have a 1.5" air gap on back so it is truly a,1.5" panel.


----------



## dnoonie

robc1976 said:


> totally 100% true.
> 
> Also, some companies advertise a 3" panel but have a 1.5" air gap on back so it is truly a,1.5" panel.


I've been very pleased with Acoustimac panels and customer service, no complaints there.

Cheers,


----------



## dnoonie

A couple days ago I raised the diffusion beside my front speakers 14 inches, the grey covered item is the diffusion. It made a remarkable difference, the front and rear speakers are much more blended, there used to be a bit of a hole about half way between the front main and the MLP, that space is much more blended with the rear surrounds now. I've attached a pic. I was very surprised at what a minor placement change could make to the sound. My front stereo sound stage is still pretty much the same.

I also attached a pic of the rear diffusion, it's stained and finished now. The HT room is still not done, more finishing touches to do.

Cheers,


----------



## dnoonie

Awhile back some asked me about why to use a tall made of metal mirror. I didn't illustrate it at the time so here's some pics.

The bottom line is that they make checking reflection points by yourself a breeze, they cost less that $20, they're light weight, they don't break.

Cheers,


----------



## Lesmor

dnoonie said:


> A couple days ago I raised the diffusion beside my front speakers 14 inches, the grey covered item is the diffusion. It made a remarkable difference, the front and rear speakers are much more blended, there used to be a bit of a hole about half way between the front main and the MLP, that space is much more blended with the rear surrounds now. I've attached a pic. I was very surprised at what a minor placement change could make to the sound. My front stereo sound stage is still pretty much the same.
> 
> I also attached a pic of the rear diffusion, it's stained and finished now. The HT room is still not done, more finishing touches to do.
> 
> Cheers,


Nice treatments liking the rear diffusers look very nice


----------



## kciaccio

Interesting video showing the effects of adding various treatments..


----------



## RoboAVS

Pardon the interruption, I wanted to take just a moment to thank all the contributors to this thread. I have read/breezed through the first half -- yes, over 5000 posts, over time, and have found the information invaluable.

Since the thread was started so long ago, I have no idea if any of the original professionals still are around but a special thank you to all of you for your contributions.

I learned a lot, enough to treat my room and get great benefits both by listening and measuring.

THANK YOU


----------



## robc1976

RoboAVS said:


> Pardon the interruption, I wanted to take just a moment to thank all the contributors to this thread. I have read/breezed through the first half -- yes, over 5000 posts, over time, and have found the information invaluable.
> 
> Since the thread was started so long ago, I have no idea if any of the original professionals still are around but a special thank you to all of you for your contributions.
> 
> I learned a lot, enough to treat my room and get great benefits both by listening and measuring.
> 
> THANK YOU


 totally agree 100%


----------



## austin85

Update: I now have the following treatment en-route and will get some measurements and thoughts posted after Christmas.

Front Corners: 4x GIK Soffit Bass Traps, Full Range (Floor to Ceiling)
Rear Corners: 4x GIK Soffit Bass Traps, Range Limited (Floor to Ceiling)
Rear Wall: 3x GIK Polyfusers

I'd still like any thoughts regarding the use of GIK 244 panels vs. GIK Q7D diffusors on the first order reflection points. The 244's reportedly tighten the sound image while the Q7Ds offer a more expansive soundstage. Since the Triton Ones (will be getting them early next year) image so well out of the box, I'm leaning towards Q7D diffusors for the first order and 244's for the second order. Is there anyone that have tried both and have any advice? Bryan (from GIK) noted that I can move a some soffit bass traps and place them @ the first order reflections to get an idea of what 244's will sound like. I will likely do the same with their Gridfusors at the first order (although, they'll ultimately be for the rear side wall for diffusion) to get a rough idea of what their Q7D's may sound like - hopefully giving me enough info to make a decision .


----------



## dnoonie

austin85 said:


> Update: I now have the following treatment en-route and will get some measurements and thoughts posted after Christmas.
> 
> Front Corners: 4x GIK Soffit Bass Traps, Full Range (Floor to Ceiling)
> Rear Corners: 4x GIK Soffit Bass Traps, Range Limited (Floor to Ceiling)
> Rear Wall: 3x GIK Polyfusers
> 
> I'd still like any thoughts regarding the use of GIK 244 panels vs. GIK Q7D diffusors on the first order reflection points. The 244's reportedly tighten the sound image while the Q7Ds offer a more expansive soundstage. Since the Triton Ones (will be getting them early next year) image so well out of the box, I'm leaning towards Q7D diffusors for the first order and 244's for the second order. Is there anyone that have tried both and have any advice? Bryan (from GIK) noted that I can move a some soffit bass traps and place them @ the first order reflections to get an idea of what 244's will sound like. I will likely do the same with their Gridfusors at the first order (although, they'll ultimately be for the rear side wall for diffusion) to get a rough idea of what their Q7D's may sound like - hopefully giving me enough info to make a decision .


Cool! Sounds like a great start. I'm looking to replace absorption with GIK Polyfusor on my back wall when I can!

Absorption vs diffusion.
The rule of thumb for placement is to allow a foot of distance for each inch of thickness of the diffusion. Less than that and it will smear imaging. I tried diffusion at first reflection points in my 12 foot wide HT room and it didn't work. I have it in back by the surrounds, beside the mains and behind the mains, these positions work great, see pics a few posts back, grey boxes are diffusion. If you think you have the space try it, you might like it. If you're close to not having enough space (like I was) get it and try it but have a backup plan for placement.

I've found that diffusion creates a more spacious sounding space but does not (in my limited experience) seem to widen the sound stage but does add depth to the sound stage. Instruments will go farther behind the speakers and farther in front of the speakers.

Another way to look at it with an oversimplified sound byte...If you like a more spacious sound you'll like diffusion, if you like a more intimate sound you'll like absorption.

Cheers,


----------



## austin85

dnoonie said:


> Cool! Sounds like a great start. I'm looking to replace absorption with GIK Polyfusor on my back wall when I can!
> 
> Absorption vs diffusion.
> The rule of thumb for placement is to allow a foot of distance for each inch of thickness of the diffusion. Less than that and it will smear imaging. I tried diffusion at first reflection points in my 12 foot wide HT room and it didn't work. I have it in back by the surrounds, beside the mains and behind the mains, these positions work great, see pics a few posts back, grey boxes are diffusion. If you think you have the space try it, you might like it. If you're close to not having enough space (like I was) get it and try it but have a backup plan for placement.
> 
> I've found that diffusion creates a more spacious sounding space but does not (in my limited experience) seem to widen the sound stage but does add depth to the sound stage. Instruments will go farther behind the speakers and farther in front of the speakers.
> 
> Another way to look at it with an oversimplified sound byte...If you like a more spacious sound you'll like diffusion, if you like a more intimate sound you'll like absorption.
> 
> Cheers,


Thanks for the feedback. Given that my room isn't much wider than yours (mine = 12' 9" wide), 244's might be the way to go. Of course, it's always challenging to say what I'd most prefer without truly trying both options (244 or Q7Ds). I could definitely repurpose the Q7Ds for rear side wall diffusion, but one downside is that they're a bit pricy compared to GIK's other diffusion products.


----------



## robc1976

austin85 said:


> Thanks for the feedback. Given that my room isn't much wider than yours (mine = 12' 9" wide), 244's might be the way to go. Of course, it's always challenging to say what I'd most prefer without truly trying both options (244 or Q7Ds). I could definitely repurpose the Q7Ds for rear side wall diffusion, but one downside is that they're a bit pricy compared to GIK's other diffusion products.


I use 242 panels on 1st sidewall reflections, 244 on 1st reflection points on ceiling, GIK monster bass traps on rear wall, tritraps in corners and diffusion on backwall on outside of monster traps.


----------



## austin85

robc1976 said:


> I use 242 panels on 1st sidewall reflections, 244 on 1st reflection points on ceiling, GIK monster bass traps on rear wall, tritraps in corners and diffusion on backwall on outside of monster traps.


Nice setup! Bryan noted that he now recommends 244's for side wall and ceiling reflections since they do a better job at absorbing lower frequency sound than the 242's, but I'm sure both sound great. I can't say I've seen a set of front speakers outside of the main front speakers - how are those leveraged?


----------



## robc1976

austin85 said:


> Nice setup! Bryan noted that he now recommends 244's for side wall and ceiling reflections since they do a better job at absorbing lower frequency sound than the 242's, but I'm sure both sound great. I can't say I've seen a set of front speakers outside of the main front speakers - how are those leveraged?


 those are wides, I run audyssey DSX (A-DSX)


----------



## myfipie

austin85 said:


> Thanks for the feedback. Given that my room isn't much wider than yours (mine = 12' 9" wide), 244's might be the way to go. Of course, it's always challenging to say what I'd most prefer without truly trying both options (244 or Q7Ds). I could definitely repurpose the Q7Ds for rear side wall diffusion, but one downside is that they're a bit pricy compared to GIK's other diffusion products.


That is always a tough call with the early reflection points. If the room was a mastering or mix room I would recommend the 244 (full range) for sure. Basically you want to only hear what is coming out of the speakers, not the speakers plus some of the side wall diffused. If the room is not for production then it really is personal taste. When you use diffusion on the sidewalls it for sure makes the sound stage "wider" but that is due to the reflection. Some like this while others don't. Personally when I am just listening to music I like to use both depending on my mode.


----------



## robc1976

myfipie said:


> That is always a tough call with the early reflection points. If the room was a mastering or mix room I would recommend the 244 (full range) for sure. Basically you want to only hear what is coming out of the speakers, not the speakers plus some of the side wall diffused. If the room is not for production then it really is personal taste. When you use diffusion on the sidewalls it for sure makes the sound stage "wider" but that is due to the reflection. Some like this while others don't. Personally when I am just listening to music I like to use both depending on my mode.


 agreed, I am changing everything to 244 with GIK scatter plates.


----------



## robc1976

Would like to acknowledge byrans great service at GIK, no better INMHO


----------



## austin85

myfipie said:


> That is always a tough call with the early reflection points. If the room was a mastering or mix room I would recommend the 244 (full range) for sure. Basically you want to only hear what is coming out of the speakers, not the speakers plus some of the side wall diffused. If the room is not for production then it really is personal taste. When you use diffusion on the sidewalls it for sure makes the sound stage "wider" but that is due to the reflection. Some like this while others don't. Personally when I am just listening to music I like to use both depending on my mode.


Thanks, Glenn - that's very good insight. Perhaps I just need to build a rotating panel with one side diffusion and the other side absorption, lol. I may just end up treating the first order with Q7Ds on the sidewalls and 244's for the ceiling and second order. Worst case, I can re-purpose the Q7Ds to the rear side wall if I tend to prefer 244s. I'd imagine that, between treating the ceiling and second order with 244's, it will tighten the image a bit while also allowing the Q7Ds at the first order to maintain some of the spaciousness in the room.


----------



## robc1976

austin85 said:


> Thanks, Glenn - that's very good insight. Perhaps I just need to build a rotating panel with one side diffusion and the other side absorption, lol. I may just end up treating the first order with Q7Ds on the sidewalls and 244's for the ceiling and second order. Worst case, I can re-purpose the Q7Ds to the rear side wall if I tend to prefer 244s. I'd imagine that, between treating the ceiling and second order with 244's, it will tighten the image a bit while also allowing the Q7Ds at the first order to maintain some of the spaciousness in the room.


reflection points on ceiling imho are the most important.


----------



## dnoonie

myfipie said:


> *When you use diffusion on the sidewalls it for sure makes the sound stage "wider"* but that is due to the reflection. Some like this while others don't. Personally when I am just listening to music I like to use both depending on my mode.


Thanks for that Glenn! I've always wondered but not had the proper space to check.

Cheers,


----------



## dnoonie

austin85 said:


> Thanks, Glenn - that's very good insight. Perhaps I just need to build a rotating panel with one side diffusion and the other side absorption, lol. * I may just end up treating the first order with Q7Ds on the sidewalls *and 244's for the ceiling and second order. Worst case, I can re-purpose the Q7Ds to the rear side wall if I tend to prefer 244s. I'd imagine that, between treating the ceiling and second order with 244's, it will tighten the image a bit while also allowing the Q7Ds at the first order to maintain some of the spaciousness in the room.


I think it's worth a try. My exact dimension on the width is 11' 7" so you are over a foot wider which may work for you.

I think it's fun to try things, yes it's a bit of work and I don't always have the time but it's fun when I have the time. I hope you enjoy the process! I really like what the QRDs did for my surround, so if you are into movies I don't think you'll be disappointed with the backup plan.

Cheers,


----------



## rboster

robc1976 said:


> reflection points on ceiling imho are the most important.


I'm worried about treating the ceiling with absorption panels between the two in-ceiling atmos speakers. anyone have any thoughts or examples what they have done?


----------



## Witchboard

rboster said:


> I'm worried about treating the ceiling with absorption panels between the two in-ceiling atmos speakers. anyone have any thoughts or examples what they have done?


I'm also currently starting to research cloud absorption panels for my room. I'm just looking at hitting my first reflections, but I would think that it would even be more important with Atmos speakers so they don't get drown out.

Question for myself. I have an open doorway to another room that lays where the first reflections are on my right wall. Obviously since there's no wall, there's no reflection. Should I try and make the left wall opposite of the door in the first reflection point as dead as possible to match the open doorway?


----------



## rboster

Witchboard said:


> I'm also currently starting to research cloud absorption panels for my room. I'm just looking at hitting my first reflections, but I would think that it would even be more important with Atmos speakers so they don't get drown out.
> 
> Question for myself. I have an open doorway to another room that lays where the first reflections are on my right wall. Obviously since there's no wall, there's no reflection. Should I try and make the left wall opposite of the door in the first reflection point as dead as possible to match the open doorway?


In my situation, I have an enclosed room...the first reflection hits between the front height atmos speakers and the middle height atmos speakers (on both sides of the room). I would normally place high freq 1-2 inch absorption panels in that spot...my concern is will it negatively impact the atmos front/middle atmos speakers by having the absorption panels btw the two pairs by deadening the dispersion properties of the atmos speakers?


----------



## Witchboard

rboster said:


> In my situation, I have an enclosed room...the first reflection hits between the front height atmos speakers and the middle height atmos speakers (on both sides of the room). I would normally place high freq 1-2 inch absorption panels in that spot...my concern is will it negatively impact the atmos front/middle atmos speakers by having the absorption panels btw the two pairs by deadening the dispersion properties of the atmos speakers?


I guess it would depend on your speakers and their dispersion pattern and how low you plan on hanging your cloud. As you mentioned a 2" panel, I would presume you'd hang it 2" from the ceiling. I would think as long as you can see your in ceiling speakers from you listening points under the 4", then it would be fine, but that's just me being presumptuous. I'm in here trying to learn as well so hopefully somebody with more knowledge will chime in.


----------



## robc1976

Witchboard said:


> I guess it would depend on your speakers and their dispersion pattern and how low you plan on hanging your cloud. As you mentioned a 2" panel, I would presume you'd hang it 2" from the ceiling. I would think as long as you can see your in ceiling speakers from you listening points under the 4", then it would be fine, but that's just me being presumptuous. I'm in here trying to learn as well so hopefully somebody with more knowledge will chime in.


 that's why I like GIK, they have a 1.75-2" air gap in back so I hang them 1-2" from ceiling and they are 3-4" from ceiling to actual back of panel.


----------



## donktard

Hey guys.
I have a home theater AKA living room about 21' x 15' with partially slanted ceiling. Since there is a support beam in the middle, I am forced to use 1/4 (literarly a quadrant) of a room as a HT (5.1). Room is covered in wood paneling, one wall is drywall. I placed DIY acoustic panels 4" thick made of rockwool at early reflections of front and center channels, but I am not satisfied with results.
I have attached T30 and ETC of my center channel.
My goal is to bring T30 between 0.2 and 0.3 across the frequency range. I have 12 2'x4' and 3 2'x2' DIY traps at disposal to experiment with. What would be the best course of action to accomplish this? Distribute evenly at all large flat surfaces? Aim specifically for secondary reflections? Attack some corners?

My second goal is to fix first 5 ms of Impulse response. I know that first big spike at about 1ms is floor bounce and I can remove that one with trap on a floor right in front of center channel. Second one, at about 2.5 ms is impossible for me to find. I have moved few of my free panels everywhere but I just can't bring it down. I assumed that my panels might be ineffective, so I ran sweeps from 1k-10k and from 10k-20k separately only to notice that both of those sweeps have same spike, so my assumption is that my panels should be effective at fixing that.
Any suggestions for more effective pinpointing of that reflection?

Thanks.


----------



## xylem

HI, i am fairly new to this and have been browsing the pages but i still have questions.
For a sound absorption panel, with decorative fabric on top, which material is the best for price/performance to add inside the panel?
UltraTouch Denim Insulation, Roxul Safe n sounds, Towels ;-) , others?

thank you.


----------



## donktard

I am also curious how effective is Denim Ultratouch compared to here quite popular OC insulation.


----------



## Witchboard

http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## ereed

Added GIK 244 bass traps with range limiter on my rear wall and 4A alpha panel absorber/diffuser on my first reflection points in my open floor plan living room which was very echo-y and the sound is MUCH better! Bass is tighter with faster improved decay times and the soundstage is wide and better imaging at the same time. Wish I could put panels on the ceiling but the wife won't let me do this in a living room but just 3 alpha panels and 3 244 panels just on 2 walls made a big difference alone. I can't imagine how a fully treated room would sound.


----------



## ereed

Here is mine from GIK. 244 Panels are Coffee color fabric and the 4A alpha panels are coffee color with black front. Looks little darker in the pics than in person though.


----------



## robc1976

ereed said:


> Here is mine from GIK. 244 Panels are Coffee color fabric and the 4A alpha panels are coffee color with black front. Looks little darker in the pics than in person though.


 you have the scatter plates in those babies! Very nice. I am switching out 32 panels (242) and going with 244 with scatter plates


----------



## robc1976

ereed said:


> Added GIK 244 bass traps with range limiter on my rear wall and 4A alpha panel absorber/diffuser on my first reflection points in my open floor plan living room which was very echo-y and the sound is MUCH better! Bass is tighter with faster improved decay times and the soundstage is wide and better imaging at the same time. Wish I could put panels on the ceiling but the wife won't let me do this in a living room but just 3 alpha panels and 3 244 panels just on 2 walls made a big difference alone. I can't imagine how a fully treated room would sound.


 makes a world of difference, I can't imagine my room with no treatments and 9 horn loaded tweeters....good by ears!


----------



## ereed

robc1976 said:


> you have the scatter plates in those babies! Very nice. I am switching out 32 panels (242) and going with 244 with scatter plates


If I'm correct switching out the 242 to 244 will just give you more bass absorption since they are about 5 inches thick.

My rear wall is 244 bass trap panels with range limiters built in. The 4A alpha panels comes with built in scatter plates since its absorber and diffuser all in one product. But I got the 4 inch version so it can absorb more low frequencies as well. Since I don't and am not using corner bass traps it made sense to go with really thick panels all around in my room to compensate. 

I do have short half wall (4 feet tall) on left side that opens to the kitchen and its also a first reflection point and I will be adding another alpha panel on that side eventually (not sure if it would help). Having an open floor plan with hardwoods can be challenging for sure.


----------



## robc1976

ereed said:


> If I'm correct switching out the 242 to 244 will just give you more bass absorption since they are about 5 inches thick.
> 
> My rear wall is 244 bass trap panels with range limiters built in. The 4A alpha panels comes with built in scatter plates since its absorber and diffuser all in one product. But I got the 4 inch version so it can absorb more low frequencies as well. Since I don't and am not using corner bass traps it made sense to go with really thick panels all around in my room to compensate.
> 
> I do have short half wall (4 feet tall) on left side that opens to the kitchen and its also a first reflection point and I will be adding another alpha panel on that side eventually (not sure if it would help). Having an open floor plan with hardwoods can be challenging for sure.


I have monster GIK (8") bass traps on rear wall with diffusion. Bpape suggests 244 on ceiling also, will keep 242 on side walls 1st reflection. I also have floor to ceiling tri-traps


----------



## ereed

robc1976 said:


> I have monster GIK (8") bass traps on rear wall with diffusion. Bpape suggests 244 on ceiling also, will keep 242 on side walls 1st reflection. I also have floor to ceiling tri-traps


Nice. The wife won't let me do all that in a living room. haha So did what I could that helps with sound and still look good.


----------



## robc1976

ereed said:


> Nice. The wife won't let me do all that in a living room. haha So did what I could that helps with sound and still look good.


I am sure it looks and sounds great. Have you showed her the soffit traps? They look amazing on the top of the parameter of a room, they are expensive but add great bass control and look great


----------



## asarose247

Building my own panels, these last 2 on the front wall, as in the first pic, on the left

covered in 2 layers of this: https://www.amazon.com/gp/product/B0071OU738/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

#2 close up of layers, the base and my drywall corner construction

#3 before and after


----------



## ereed

asarose247 said:


> Building my own panels, these last 2 on the front wall, as in the first pic, on the left
> 
> covered in 2 layers of this: https://www.amazon.com/gp/product/B0071OU738/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
> 
> #2 close up of layers, the base and my drywall corner construction
> 
> #3 before and after


Looks good. I'm not that handy to go DIY. How does it sound?


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## asarose247

iN TOTAL IN MY MAIN LISTENING AREA, about 14.5 x 18-ish deep, (the "room" is actually 28ish ft deep and the total volume is close to 5k ft^3) I have close to 150 sq ft of panels, most 5" thick, some 2 x 4 ft x 18" deep wedges in ceiling corners, the 2 small zebra looking base trap ( very effective I'm sure) and 20 sq ft of 3" first reflection sidewall panels.

It's quiet in that seat under the in ceiling light, under the SCatmos cloud. immediately noticable when stepping into the center of things.
really makes everything so much more clear,
I can use a lower MV and hear stuff with more clarity, depth, fuller sound stage 

For Diy you could use lumber from HD, etc. cut to lenght, , pneumatic staple gun , Harbor Freight? maybe and compressor.
check out you tube for videos, also HTS, gearsluts, audioholics and of course AVS.

the hard part is having an idea/ the science where to put them. 
the really hard part , for some, getting permission.
the really easy part, for some, writing a check . .
YMMV


----------



## itallushrt

What is the consensus on the preferred way to hang 48x24x2 panels from the ceiling in a room with a short ceiling (7')? With such a short headspace using the 4" "cloud brackets" is out of the question. 

As such I'm assuming small lag eye bolts on 4 corners and either lag hooks or hooks in toggle bolts based on how lucky one gets...

thoughts? 

thanks!


----------



## asarose247

^ a toughie . . 

that ran thru my mind as a possibility in a tight circumstance such as that, the "anchor" goes where it needs to . .

there are low profile 2 part clips I've seen on Amazon but the need for alignment/placement exactness looked like a major headache


----------



## hobsocc7

Craft your own wood L brackets. With a lip or velco

Sent from my Pixel using Tapatalk


----------



## itallushrt

asarose247 said:


> ^ a toughie . .
> 
> that ran thru my mind as a possibility in a tight circumstance such as that, the "anchor" goes where it needs to . .
> 
> there are low profile 2 part clips I've seen on Amazon but the need for alignment/placement exactness looked like a major headache





hobsocc7 said:


> Craft your own wood L brackets. With a lip or velco
> 
> Sent from my Pixel using Tapatalk


These are both on the short list. I've DIY'ed the panels and for my wall mounts I did make my own french cleats. 

Probably do something similar for the ceiling.


----------



## drunkpenguin

Hey guys!

When I built my theater 10 years ago everybody said to treat the entire front wall with 1" thick panels. That's what I did back then, but I'm remodeling the front wall this time with a nice stage to surround the screen. It seems that now a days the thought is to NOT treat the entire front wall. So now I'm confused and need some advice.

I have huge home made base traps in all 4 corners of the room already and 1" thick wall to wall panels on the sides from ear level down. 

I'm thinking about leaving the front untreated, but my brain says this is wrong. I've read Ethans approach to it and he says it's not needed if you address the corner traps, but what about directly behind the speakers? Should I treat that area some? Most of the nice theaters I see online are using little to no treatment on the front.

What would you do?


----------



## dnoonie

itallushrt said:


> What is the consensus on the preferred way to hang 48x24x2 panels from the ceiling in a room with a short ceiling (7')? With such a short headspace using the 4" "cloud brackets" is out of the question.
> 
> As such I'm assuming small lag eye bolts on 4 corners and either lag hooks or hooks in toggle bolts based on how lucky one gets...
> 
> thoughts?
> 
> thanks!


I did hooks and eyes in my space and connected them with nylon ties, it works but if you want flush mount... 

If you have a smooth ceiling you can use a standard french cleat/z-clip system to flush mount, use one set top, one set bottom and have them appose each other, you'll have to measure pretty accurate. I'd suggest these, http://www.acoustimac.com/zbar12, as apposed to some other designs they have a little wiggle room, don't use the ones from ATS without a mounting strip, they are high quality but are such a tight fit (precision, no wiggle room) they will tear up a wall or ceiling when putting on or taking off a panel unless you use a spacer/mounting strip (I used a strip of plywood as a mounting strip screwed into studs/truss).

Cheers,


----------



## asoofi1

If you place a Linacoustic 'membrane trap' (1" / 3mil poly / 1") on the entire front wall, will corner bass traps in the back corners still be necessary or beneficial?


----------



## audiovideoholic

asoofi1 said:


> If you place a Linacoustic 'membrane trap' (1" / 3mil poly / 1") on the entire front wall, will corner bass traps in the back corners still be necessary or beneficial?


1" plastic 1" is dampening Mid and higher frequencies. Corner traps are dampening for lower frequencies. Two different things but both useful when needed.


----------



## audiovideoholic

robc1976 said:


> I am sure it looks and sounds great. Have you showed her the soffit traps? They look amazing on the top of the parameter of a room, they are expensive but add great bass control and look great


Can you link which soffit traps you are talking about please?

Never mind I see what you are talking about. Soffit makes me think of tray ceilings when talking home theater but guess could use them to create the actual soffits if didn't need any lighting or trim work.


----------



## KKoepp31

Can't seem to find a good answer on how to handle treating my setup. I've got a 120" screen on a concrete basement wall that is stamped to look like brick, sealed and painted white. The screen is on the long wall of the rectangular basement, in the middle of a roughly 900sqft area, with usable space on both sides of the screen. Finishing the wall with studs, drywall, etc isn't in the cards right now, but I'd like to frame out something around the screen to darken the area immediately around it. The screen is not acoustically transparent and I have large towers that sit outside of the screen, with a center that sits below and in the middle.

My thought is to frame out roughly 2 feet beyond the screen on both ends to help hide the towers. I'll stuff this framing with 3.5" Thermafiber UltraBatt mineral wool insulation because it's really cheap at Menards and I've got gift card money that need to be used up. Should I use a heavy velvet to absorb light or use GOF FR701 in order to allow sound to get to the mineral wool, or does it not matter which I use? Since the screen is not transparent, does it matter if I treat this area?

The room really needs some help as it's a pretty large room with nothing other than a few recliners, a drop ceiling, and carpet to aid in knocking down reflections. I'll add some panels in other areas to aid in this. The panels in the drop ceiling are standard tiles. Is there much benefit in swapping these for a tile that is specified for acoustical treatment? I've got pink stuff in the joists above most of the theater area tiles.


----------



## adam5022

sorry if I'm going off topic for someone, but i have an issue with acoustics that i want to put up.

I'm going to be making my own acoustic panels, (50mm rock wool) but my first reflection point is directly in the middle of my wall mounted speaker. not too sure what i should do, should i make the panel in 2 halves and put top and bottom? remake the shelf and put it behind the speaker? ( which is effort that ide rather not do as i only just wall mounted the speaker about 3 weeks ago)

also wondering if i should be using different density rock wool sheets around the room, or is just the 1 type ok for starters?

thanks guys

I'm trying to show a picture but having trouble loading it for some reason

speaker sitting about 1m up from the ground with flat wall all around it


----------



## Lesmor

adam5022 said:


> sorry if I'm going off topic for someone, but i have an issue with acoustics that i want to put up.
> 
> I'm going to be making my own acoustic panels, (50mm rock wool) but my first reflection point is directly in the middle of my wall mounted speaker. not too sure what i should do, should i make the panel in 2 halves and put top and bottom? remake the shelf and put it behind the speaker? ( which is effort that ide rather not do as i only just wall mounted the speaker about 3 weeks ago)
> 
> also wondering if i should be using different density rock wool sheets around the room, or is just the 1 type ok for starters?
> 
> thanks guys
> 
> I'm trying to show a picture but having trouble loading it for some reason
> 
> speaker sitting about 1m up from the ground with flat wall all around it


Which speaker is that mirror on?

A first reflection is normally associated with a Left or right speaker and wouldnt reflect onto another speaker unless.

The one shown is a wide speaker,which is unlikely.

The one shown is a surround speaker, in which case it has not been mounted in the right place and is too far forward.


----------



## erwinfrombelgium

adam5022 said:


> sorry if I'm going off topic for someone, but i have an issue with acoustics that i want to put up.
> 
> I'm going to be making my own acoustic panels, (50mm rock wool) but my first reflection point is directly in the middle of my wall mounted speaker. not too sure what i should do, should i make the panel in 2 halves and put top and bottom? remake the shelf and put it behind the speaker? ( which is effort that ide rather not do as i only just wall mounted the speaker about 3 weeks ago)
> 
> also wondering if i should be using different density rock wool sheets around the room, or is just the 1 type ok for starters?
> 
> thanks guys
> 
> I'm trying to show a picture but having trouble loading it for some reason
> 
> speaker sitting about 1m up from the ground with flat wall all around it


If you make 2 halves on top and bottom, you will have reflection at the actual height of the side speaker (1 m), right? So i'd say that's not best practice.

Regarding density: heavier stuff be a bit more performant on lower frequencies.


----------



## adam5022

Lesmor said:


> Which speaker is that mirror on?
> 
> A first reflection is normally associated with a Left or right speaker and wouldnt reflect onto another speaker unless.
> 
> The one shown is a wide speaker,which is unlikely.
> 
> The one shown is a surround speaker, in which case it has not been mounted in the right place and is too far forward.


thats my surround right. due to the size of my room and a doorway being very near its the only spot for it. this acoustic stuff is really new to me, so any suggestions would be great


----------



## adam5022

erwinfrombelgium said:


> If you make 2 halves on top and bottom, you will have reflection at the actual height of the side speaker (1 m), right? So i'd say that's not best practice.
> 
> Regarding density: heavier stuff be a bit more performant on lower frequencies.


could i do a half and half panels (top and bottom) and some foam either side of the speaker in-between the panels? i assume having a big thick panel either side of the speaker is no good as it will start blocking the speakers side firing. but maybe thin foam? not perfect, but something?


----------



## erwinfrombelgium

Something is always better than nothing. But thin (less than 2" / 5 cm) material like foam (and carpet) only absorbs high frequencies. 

A small surface of absorption is also not going to turn a fairly naked space into audio nirvana. 

There are so many factors coming into play that some reading on the subject would be advised. The more you read, the more you realize how complicated this stuff is. 

In the end you start having weird ideas. I recently started to think I could have had an ever better space if I had made it double height: half in the basement, half above. Would have been 5 m high! It just gets to you. But don't tell anyone or they lock me up for being a proper madman.


----------



## adam5022

My wife already thinks I'm mad!! Hahaha it's so true! Funny as hell


----------



## xxrb1

Side panels - first reflection point - moveable on rail

Question about attaching side acoustical panels (first reflection point) on rail allowing the panel to move left or right in order to hide windows on one side and a TV screen on the other side when projector in use. Panels can be 242 or 244 from GIK acoustic or something similar.

The panels can be directly attached from the top to the rails located under the left and right soffits, or the panel are attached to vertical planks which are connected to the top rails. Think about a barn door/pocket door and you attach the panel on the barn door/pocket door.

Is there any issue mounting panels such as way? Indeed, there will be a space between the panel and the wall or between the panel/plank and wall.

Thanks for feedback


----------



## erwinfrombelgium

All for the better! As long as the gap between panel and wall is not more than the thickness of the panels, you are only increasing their effectiveness to a lower frequency!!!


----------



## austin85

FYI, I created a new thread w/ many measurements to demonstrate the impact GIK soffit bass traps and Polyfusors had in my room: http://www.avsforum.com/forum/19-de...n-s-dedicated-theater-build.html#post49648689


----------



## asarose247

@xxrb1

French cleats come to mind,
either DIY plywood 
or hangman (iirc) from amazon, home depot

hangman can be more discrete,

some pics could help

HTH


----------



## xxrb1

asarose247 said:


> @xxrb1
> 
> French cleats come to mind,
> either DIY plywood
> or hangman (iirc) from amazon, home depot
> 
> hangman can be more discrete,
> 
> some pics could help
> 
> HTH


Thanks for your advice,

I like the french cleat idea.

The reasons for moving panels are two fold:

- I am lazy on repetitive stuff and carrying 6 huge panels each time I want to watch a movie that will not cut it
- when not in use, finding a place for 6 big panels will not be easy and not wife approved


----------



## xxrb1

erwinfrombelgium said:


> All for the better! As long as the gap between panel and wall is not more than the thickness of the panels, you are only increasing their effectiveness to a lower frequency!!!


Thanks, that helps designing the railing system


----------



## erwinfrombelgium

Rereading your original post: just make sure the sound can actually go through the absorber. So don't attach it to a panel.


----------



## HopefulFred

xxrb1 said:


> Side panels - first reflection point - moveable on rail
> 
> Think about a barn door/pocket door and you attach the panel on the barn door/pocket door.
> 
> Is there any issue mounting panels such as way?
> 
> Thanks for feedback


Rattling may prove problematic with bass.


----------



## xxrb1

erwinfrombelgium said:


> Rereading your original post: just make sure the sound can actually go through the absorber. So don't attach it to a panel.


Panels are in front of the planks: room - acoustical panel - plank - wall


----------



## xxrb1

HopefulFred said:


> Rattling may prove problematic with bass.



I was thinking about that, but have no experience yet.


----------



## erwinfrombelgium

*Limp Mass Bass Absorbers*

I have been reading about *Limp Mass Bass Absorbers* mainly on Gearslutz. 

Although at this point I have no idea if I am even going to have bass issues in my finished 16-channel room once I start to use it! Because of the construction of double drywall with Green Glue in between, on top of OSB on a wood frame, decoupled and using a decoupled concrete floor, I hope that mid-bass is largely absorbed and expect sub-bass to go right through. From upper bass onwards, I am already good I think.

But if REW would indeed show the issues the Room Modes Calculators predict between 20-65 Hz, I think Limp Bass Absorbers are the way to go because their ability to target specific frequencies using a relatively shallow enclosure. BTW, my subs are tuned to 13 Hz but this ultra low hZ will not be stopped unless you use military grade construction.

I found a mass loaded vinyl (MLV) called "akoestisch membraan 10" from Rockwool here in Belgium which they use on industrial flat roofs to reduce sounds from rain and airplanes. It's 5.2 mm thickness and is a very good 10 kg / m2 heavy. 

Product sheet in dutch:
Akoestisch membraan 5 and 10

Using a simple formula: 600 / (weight[kg]*depth[cm]) 
for example using "akoestisch membraan 10":
600 / 10 kg * 15 cm = 40 Hz
600 / 10 kg * 20 cm = 30 Hz
600 / 10 kg * 30 cm = 20 Hz
600 / 10 kg * 40 cm = 15 Hz

If the membrane is only 5 kg (such as EPDM), the Hz values double. Given a fixed depth, a mixture of both 5 kg and 10 kg membrane should be effective if used on 20% of the surface. Which is admittedly more surface than available. Though I could probably do a stack of 40 cm depth in a corner. And there is still a good deal of ceiling surface left where I could use 20 cm depth on.

More:
Tim's Limp Bass Absorbers on Gearslutz

Any suggestions or experiences?


----------



## eightninesuited

*Hi guys, need some help!*


I've been out of the game for the past 7 years. Got married, had kids, lost interest, etc...


I've bought a house with an unfinished basement that's 18x12 feet of space I want to build a home theater in. 


I have a 7.1 Energy RC setup with a SVS PB10 subwoofer. I'll work on these later. 


For now, I need some assistance with low cost acoustic treatments. I've never really looked at these before, but it seems the prices are outrageous for a bunch of foam that you find as throwaways when you buy appliances, etc... 


Can someone recommend me some cheap acoustic treatments for an unfinished basement? I'm getting a Persian style rug to go on the floor for now, but walls are still an issue.


----------



## erwinfrombelgium

Sure we can! The magic word is... DIY! Make em as thick as possible!


----------



## HopefulFred

erwinfrombelgium said:


> I have been reading about *Limp Mass Bass Absorbers* mainly on Gearslutz.
> 
> But if REW would indeed show the issues the Room Modes Calculators predict between 20-65 Hz, I think Limp Bass Absorbers are the way to go because their ability to target specific frequencies using a relatively shallow enclosure.
> 
> Any suggestions or experiences?


Have you tried to configure a Helmholtz for that band?


----------



## erwinfrombelgium

No, not yet.


----------



## HopefulFred

I found that getting a helmholtz trap band to be good (above 0.5 absorption coeff or so) was pretty tough below 80 Hz, but I was looking for absorption up to Schroedinger or so also. If you were willing to sacrifice bandwidth, you might get it done in a pretty shallow box?


----------



## erwinfrombelgium

Thing is don't have measured yet. Until then I don't know for sure what's needed.

Still reading the 30 pages on Gearslutz and what's obvious that this kind of membrane absorbers only work where the pressure is at it's peak. So step one is measuring with REW. Then using a room mode calculator to find out where the problem frequency's are located and only then decide which bass absorber to use. Hopefully it's in a position where I have opportunity to do something useful
.


----------



## HopefulFred

erwinfrombelgium said:


> Thing is don't have measured yet. Until then I don't know for sure what's needed.


I'm with you entirely. I've been trying to manage the same task (not very busy at it). I have measurements in my build thread (and here http://www.avsforum.com/forum/91-audio-theory-setup-chat/2646481-modal-analysis.html ) which might interest you. If you have any measurements, please point me to them (PM is fine if you don't want to post it all here - I don't want to post mine here).


----------



## TKNice

Question for the experts...

I've got an unfinished area behind the wall holding my projector screen. Its a bit noisy back there because of some servers and computer gear and I'd like to add some insulation to the studs and minimize any noise in the theater.

Does it matter what R rating I get for this? I'm looking for something relatively inexpensive from Home Depot. Unless anyone has a better suggestion.

Thanks!


----------



## hobsocc7

TKNice said:


> Question for the experts...
> 
> I've got an unfinished area behind the wall holding my projector screen. Its a bit noisy back there because of some servers and computer gear and I'd like to add some insulation to the studs and minimize any noise in the theater.
> 
> Does it matter what R rating I get for this? I'm looking for something relatively inexpensive from Home Depot. Unless anyone has a better suggestion.
> 
> Thanks!


#notanexpert 
The cheapest stuff you can find but I don't think it will have a big impact 

Sent from my Pixel using Tapatalk


----------



## TKNice

hobsocc7 said:


> #notanexpert
> The cheapest stuff you can find but I don't think it will have a big impact
> 
> Sent from my Pixel using Tapatalk


No? Well, I could put up a few sheets of drywall or plywood on the other side along with the insulation. That would certainly help, right?


----------



## austin85

Bryan (GIK) noted the following regarding my latest round of measurements (the full set can be found on my thread):

Response looks pretty good and the decay time is greatly improved. Still a bit of ringing about 50 Hz which the Soffits are more than capable of addressing so my guess is that it is something in the room itself that’s resonating. I would play that tone relatively loud and wander about and see what you can find.

Any ideas of what could be causing a lot of ringing at ~50Hz? Short of my couch, I don't have much else in the room.

REW - Waterfall - No Treatment - Triton 7 + Subwoofer


REW - Waterfall - Full Soffit Treatment - Triton 7 + Subwoofer


----------



## ereed

austin85 said:


> Bryan (GIK) noted the following regarding my latest round of measurements (the full set can be found on my thread):
> 
> Response looks pretty good and the decay time is greatly improved. Still a bit of ringing about 50 Hz which the Soffits are more than capable of addressing so my guess is that it is something in the room itself that’s resonating. I would play that tone relatively loud and wander about and see what you can find.
> 
> Any ideas of what could be causing a lot of ringing at ~50Hz? Short of my couch, I don't have much else in the room.
> 
> REW - Waterfall - No Treatment - Triton 7 + Subwoofer
> 
> 
> REW - Waterfall - Full Soffit Treatment - Triton 7 + Subwoofer


I know nothing about REW or what I need for it. Would like to try it and see what its all about. Some advice what I need to get REW started other than a mic and laptop? I know when I do it I won't have "before" measurements, just the "after" since the GIK panels are already up. But it would give me idea what it looks like currently. But I will say by ear the flutters and echo are almost gone and the bass feels tighter.


----------



## dnoonie

austin85 said:


> Bryan (GIK) noted the following regarding my latest round of measurements (the full set can be found on my thread):
> 
> Response looks pretty good and the decay time is greatly improved. Still a bit of ringing about 50 Hz which the Soffits are more than capable of addressing so my guess is that it is something in the room itself that’s resonating. I would play that tone relatively loud and wander about and see what you can find.
> 
> *Any ideas of what could be causing a lot of ringing at ~50Hz? Short of my couch, I don't have much else in the room.*
> 
> REW - Waterfall - No Treatment - Triton 7 + Subwoofer
> 
> 
> REW - Waterfall - Full Soffit Treatment - Triton 7 + Subwoofer


The couch is certainly a possibility, I know my HT room has a smoother response without the couch, or even if I move the couch to the back of the room. You could try moving the couch and measuring again at the MLP to see if the response changes.

I read recently somewhere...http://www.enjoythemusic.com/magazine/equipment/0709/rythmik_f12se.htm, found it, it could be a floor to ceiling node? I'm not sure. In any case I'm replacing my ceiling traps when I can with 4" (I have 2" with plenum now, part of an affordable kit), I have a 63Hz spike. If your sub has a parametric eq like the rythmik in the article you could try using it. I check your build thread and it doesn't look like you have ceiling treatments yet. Have you put in ceiling first/second reflection point treatment?

Cheers,


----------



## sdurani

austin85 said:


> Any ideas of what could be causing a lot of ringing at ~50Hz?


The peak of that ringing frequency seems to be centered around 52Hz. 

If it is a room mode (aka resonance or standing wave), then the speed of sound divided by the ringing frequency should produce an approximate room dimension (or multiple thereof). 

1130 ÷ 52 = 21.730 

Do you have a room dimension around 22 feet (give or take a foot)? IF so, then you've found what's causing the ringing (your room).


----------



## AdvancedTheater

HopefulFred said:


> I'm with you entirely. I've been trying to manage the same task (not very busy at it). I have measurements in my build thread (and here http://www.avsforum.com/forum/91-audio-theory-setup-chat/2646481-modal-analysis.html ) which might interest you. If you have any measurements, please point me to them (PM is fine if you don't want to post it all here - I don't want to post mine here).


Link to your build ?


----------



## erwinfrombelgium

TKNice said:


> No? Well, I could put up a few sheets of drywall or plywood on the other side along with the insulation. That would certainly help, right?


Drywall is better than plywood, yes, this will help more than the fiberglass. If the construction is open then do put some in though. 

Oh, BTW: using Green Glue between 2 sheets of drywall is equally as good as 4 sheets of drywall without it.


----------



## itallushrt

TKNice said:


> Question for the experts...
> 
> I've got an unfinished area behind the wall holding my projector screen. Its a bit noisy back there because of some servers and computer gear and I'd like to add some insulation to the studs and minimize any noise in the theater.
> 
> Does it matter what R rating I get for this? I'm looking for something relatively inexpensive from Home Depot. Unless anyone has a better suggestion.
> 
> Thanks!


This is a soundproofing question not an acoustical treatment question. 

I would recommend this video. Start at the beginning if you have time or start at the 7:50 mark if you don't. The diagram that shows up shortly after 7:50 and the related STC associated with each "method" should be what you are focusing on.


----------



## austin85

ereed said:


> I know nothing about REW or what I need for it. Would like to try it and see what its all about. Some advice what I need to get REW started other than a mic and laptop? I know when I do it I won't have "before" measurements, just the "after" since the GIK panels are already up. But it would give me idea what it looks like currently. But I will say by ear the flutters and echo are almost gone and the bass feels tighter.


Bingo, simply a computer and a mic. For the mic, I recommend the UMIK-1 from miniDSP. Also, you’ll want to get a microphone stand with an articulating arm.



dnoonie said:


> The couch is certainly a possibility, I know my HT room has a smoother response without the couch, or even if I move the couch to the back of the room. You could try moving the couch and measuring again at the MLP to see if the response changes.
> 
> I read recently somewhere...http://www.enjoythemusic.com/magazine/equipment/0709/rythmik_f12se.htm, found it, it could be a floor to ceiling node? I'm not sure. In any case I'm replacing my ceiling traps when I can with 4" (I have 2" with plenum now, part of an affordable kit), I have a 63Hz spike. If your sub has a parametric eq like the rythmik in the article you could try using it. I check your build thread and it doesn't look like you have ceiling treatments yet. Have you put in ceiling first/second reflection point treatment?
> 
> Cheers,


Unfortunately, the current couch position + speaker position was selected based on where I received the flattest response, so I’m afraid that’s optimized. I have yet to put up GIK 244 bass traps on the ceilings, but something that will happen in the not too distant future.



sdurani said:


> The peak of that ringing frequency seems to be centered around 52Hz.
> 
> If it is a room mode (aka resonance or standing wave), then the speed of sound divided by the ringing frequency should produce an approximate room dimension (or multiple thereof).
> 
> 1130 ÷ 52 = 21.730
> 
> Do you have a room dimension around 22 feet (give or take a foot)? IF so, then you've found what's causing the ringing (your room).


Bingo! My theater is 21’ 9” long, so that’s likely the issue. Any tips on how to minimize the effect short of moving my couch (since it and my speakers are placed where I achieve the flattest response)?


----------



## sdurani

austin85 said:


> My theater is 21’ 9” long, so that’s likely the issue.


The math was within a quarter inch (21.73' vs 21.75'). Ain't science grand!


> Any tips on how to minimize the effect short of moving my couch (since it and my speakers are placed where I achieve the flattest response)?


First measure your sub alone (no speakers). The 52Hz peak should be similar in all three seats on your couch. IF that is the case, a single band PEQ can be used to pull down the peak (should fix the problem across the entire couch).


----------



## dnoonie

sdurani said:


> The math was within a quarter inch (21.73' vs 21.75'). Ain't science grand!.


 Way cool...

1130/63=17.9. My room is 16' 6" long. Lot's of bass absorption on the back wall only a little on the front wall. I was going to try changing my sub x-over to 60Hz (which I like better anyway) and using the x-over sweep and main speaker shelf adjust to correct the problem. Another thought was more bass absorption on the front wall behind the front mains (although absorption at that Hz are weak). Any thoughts or comments?

Cheers,


----------



## sdurani

dnoonie said:


> Any thoughts or comments?


What problem are you trying to fix?


----------



## dnoonie

sdurani said:


> What problem are you trying to fix?


Oops, sorry. 63Hz peak.

Cheers,


----------



## sdurani

dnoonie said:


> 63Hz peak.


Is the room correction in your receiver not pulling it down? If not, can you post your room dimensions, subwoofer locations and main seating location?


----------



## dnoonie

sdurani said:


> Is the room correction in your receiver not pulling it down? If not, can you post your room dimensions, subwoofer locations and main seating location?


I have no room correction. I should make a line drawing of the room. It might take awhile for me to get to that. Thank you!

Cheers,


----------



## KKoepp31

I'd like to treat the area behind my screen. Since I have gift card money to Menards I'd like to use either Thermafiber Ultrabatt mineral wool or UltraTouch denim insulation, both in 3.5" thickness. Is there any advantage to spending a little more on denim? Denim does come in 93" lengths so this would ease install.

And is there a preferred material to cover this up with? FR701, burlap, or should it be some sort of velvet for light absorption? In any case I will be going with black. I would understand not necessarily needing to cover the area behind the screen (not an acoustically transparent screen) with fabric, but it should still be treated with insulation, correct?


----------



## rmcalhany

*Quick Fabric Panel/Frame Question*

Guys,

I have a 14'w x 23'l x 9.5' tall theater that was built by my builder to my specs a year ago (double walls, green glue, etc.). I'm now starting to work on the interior and have spent hours reading these forums and am confused as ever.

I am planning on running fabric frames like Landshark1's theater (http://www.avsforum.com/forum/19-de...y-new-home-theater-2-0-staggered-wall-ht.html) on the side and rear walls. However, I will be adding bass traps in all 4 corners.

My questions are as follows:

1) For frames of 3 depths (1", 1.5", 2") how do you fill them below the 44" height? 1" OC703/Linocoustic is easy for the 1" frame. But what do you do for the 1.5" (I assume you double the insulation for the 2" frame).

2) For frames above the 44" height, polyfill batting is ok, correct? Can that be found in all 3 thicknesses?

3) For the screen wall, I've read both 1" linocoustic and others say 1" linocoustic/3mil plastic/1" linocoustic. Given my sides, bass traps, etc., is the 1:3:1 really necessary? 

Thanks in advance.

Best,
Robert


----------



## erwinfrombelgium

Do 2" - 3" - 4" instead. 

1" is not absorbing mid frequencies.

Also if the frames are against the wall without a gap, you do not have to fill the whole depth with insulation.


----------



## Mashie Saldana

In my 12'x12' room I have an empty 24"x12" soffit along three of the walls and a 8"x12" soffit on the rear wall. What is the most suitable insulation to put in there? The effective space to fill is 10" deep due to the framing. While reading up on this it seems lower density is preferred for thick treatments and higher density for thin treatments. The question is, is 10" considered thin or thick?

As for the insulation itself I would like to go with mineral wool and can get it in either of the following kg/m3: 45, 60, 100 or 140. For the first reflection points I will go with 4" of either 60 or 100 though.

Here is the frame to be filled and then covered in fabric:


----------



## rmcalhany

erwinfrombelgium said:


> Do 2" - 3" - 4" instead.
> 
> 1" is not absorbing mid frequencies.
> 
> Also if the frames are against the wall without a gap, you do not have to fill the whole depth with insulation.


Erwin - you mean 2-4" for front/screen wall? Or side/rear walls below 44"? Or both?


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## erwinfrombelgium

While I really love the look of the room you referred to, I am not convinced it's showing best practice in acoustics.

I am not familiar with the product names but: 

the absorption is to thin, you need 2" minimum, 4" is better
placing the absorption the same distance from the wall as the thickness is best. You gain a whole octave below.
to much absorption surface on the side walls. better would be to insert some "empty" panels above 44" but not opposed to an other empty panel on the opposit wall
no ceiling absorption against first reflections are used

Edit: I checked that mysterious "linacoustic" material and compared it to standard fiberglass. In 1" thickness, both score about the same. It works for 500 Hz, not for 250 Hz! This is not acceptable. It confirms my knowledge about it.


----------



## Lasalle

Are there any different treatment goals in a high speaker count Atmos HT (ie 11.1.8) vs. a standard 7.1 room?
1) RT 60 .25-.4 or is it higher?
2) Any difference in the amount of diffusion vs absorption?
3) Best ceiling treatments around Top speaker locations, absorption or diffusion?

Sorry if this was already discussed, I only found some discussion on choosing between diffusion panels on ceiling.


----------



## Mashie Saldana

Lasalle said:


> Are there any different treatment goals in a high speaker count Atmos HT (ie 11.1.8) vs. a standard 7.1 room?


Not that I'm aware of, however if you can afford a 20 speaker system you probably should hire someone like Nyal Mellor to do the acoustic design. He is doing the design for mikela's 9.1.6 setup.


----------



## Lasalle

Mashie Saldana said:


> Not that I'm aware of, however if you can afford a 20 speaker system you probably should hire someone like Nyal Mellor to do the acoustic design. He is doing the design for mikela's 9.1.6 setup.


The Room is being Modeled by Vicoustic. I was curious as too the experiences of people in this tread.


----------



## erwinfrombelgium

Lasalle said:


> Are there any different treatment goals in a high speaker count Atmos HT (ie 11.1.8) vs. a standard 7.1 room?
> 1) RT 60 .25-.4 or is it higher?
> 2) Any difference in the amount of diffusion vs absorption?
> 3) Best ceiling treatments around Top speaker locations, absorption or diffusion?
> 
> Sorry if this was already discussed, I only found some discussion on choosing between diffusion panels on ceiling.


Well, my non-expert opinion is that more speakers need a larger amount of absorption. There are way more first reflection points, that's for sure. 

Diffusion is definitely an asset after the initial amount of absorption is applied. There are things to take into account when considering diffusion:
* Its more expensive
* It needs a certain distance to work best
* It's usually operative in a narrower bandwidth than absorption

I have a 23' wide room with standard 8 2/3' ceiling height. Hence I use diffusion on the sides and absorption on the ceiling. 

Because of the Atmos speakers, I extended the diffusion all the way to ceiling height to make sure the ceiling speakers' first reflection points are tackled. 

I only tested the acoustics with a pair of exterior speakers until now (with a nasty old CD player and ditto receiver). They sounded like a million bucks to my ears! Acoustics is 75% of the sound quality of a system. Speakers 20%. Electronics 5%. Amen!


----------



## sdurani

erwinfrombelgium said:


> Well, my non-expert opinion is that more speakers need a larger amount of absorption. There are way more first reflection points, that's for sure.


I always wondered about this. More speakers means more direct sound all around the listener. Does being swamped by direct sound mean that reflected sounds are less noticeable, so less absorption is needed? Or does that fact that ambience is now coming from speakers around the listener rather than being added by the room (like in a 2-speaker set-up) mean less relying on reflections, so more absorption should be used? I've heard valid arguments both ways.


----------



## erwinfrombelgium

I'd like to learn about those valid arguments for the former! Doesn't make sense to me.


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## sdurani

What part doesn't make sense? More speakers = more direct sound?


----------



## AdvancedTheater

More speakers just makes treatment strategy more complicated, it does not require more absorption. The same rules will apply with more speakers. Keep in mind reflections are good things, not bad things. You also don't need to worry as much about the stuff that does not hit your ears. Start with the low hanging fruit and work your way up the tree, don't go get a ladder to pick your first one.


----------



## asarose247

@erwinfrombelgium :
Because of the Atmos speakers, I extended the diffusion all the way to ceiling height to make sure the ceiling speakers' first reflection points are tackled. 

very interesting, considering the 23' wide room.

any treatment for the ATMOS speakers off axis ceiling reflection points

any links or pics?


----------



## darrellh44

Mashie Saldana said:


> In my 12'x12' room I have an empty 24"x12" soffit along three of the walls and a 8"x12" soffit on the rear wall. What is the most suitable insulation to put in there? The effective space to fill is 10" deep due to the framing. While reading up on this it seems lower density is preferred for thick treatments and higher density for thin treatments. The question is, is 10" considered thin or thick?
> 
> As for the insulation itself I would like to go with mineral wool and can get it in either of the following kg/m3: 45, 60, 100 or 140. For the first reflection points I will go with 4" of either 60 or 100 though.
> 
> Here is the frame to be filled and then covered in fabric:


I would like to hear some experts chime in as well. I'm planning on doing virtually the same thing, but my room is a little larger (22 x 13.5 x 8). The empty space in my soffits will be 15" wide x 11" high (not including the frame).


----------



## AdvancedTheater

asarose247 said:


> @erwinfrombelgium :
> Because of the Atmos speakers, I extended the diffusion all the way to ceiling height to make sure the ceiling speakers' first reflection points are tackled.
> 
> very interesting, considering the 23' wide room.
> 
> any treatment for the ATMOS speakers off axis ceiling reflection points
> 
> any links or pics?


How did you calculate the reflection points for your atmos speakers? If the speakers are overhead the area they hit the side walls and then reflect to your ears is not a common angle. A lot of the energy hitting side walls is probably directed into the floor due to the location of the speaker and it being pointed downward. 

Diffusion is often a good idea in the back half of the room. It aids envelopment, and can help make the localization of surround speakers less.


----------



## darrellh44

sdurani said:


> I always wondered about this. More speakers means more direct sound all around the listener. Does being swamped by direct sound mean that reflected sounds are less noticeable, so less absorption is needed? Or does that fact that ambience is now coming from speakers around the listener rather than being added by the room (like in a 2-speaker set-up) mean less relying on reflections, so more absorption should be used? I've heard valid arguments both ways.


In this podcast with Dennis Erskine, Dennis mentions towards the end that multi-channel HT rooms should have more sound treatments and less reverb than a 2-channel only listening room. He went on to say that it's very difficult to properly optimize a room for both applications.


----------



## AdvancedTheater

darrellh44 said:


> In this podcast with Dennis Erskine, Dennis mentions towards the end that multi-channel HT rooms should have more sound treatments and less reverb than a 2-channel only listening room. He went on to say that it's very difficult to properly optimize a room for both applications.


I think you can have good music and good movies in the same room. I would not agree with the idea you can not. I also think that using surround sound processing on music is ok, a lot of audiophile purists scoff at that idea but on a properly integrated system, with matching LCR of the same make and model and mounting heights, you can experience a very good sound stage on music. The center actually broadens the sweet spot so multiple people can simultaneously enjoy music, which I think is a nice bonus from a theater style build versus a two channel room. 

You can probably get by with a little less reflections in theater because the surround processing and channels helps aid with envelopment. 

But, and this is quite important... What people do not realize is that a lot of sonic accuracy and sonic cues come from reflections. Reflections are echoes and echoes are something that the human brain/ear can clue into for additional information regarding location, sound quality, and sonic information on space. You need them for width and envelopment, but you also need them for the detail. Echos contain much information and can add great sense of realism as well as improve sound quality. When done properly reflections can actually aid with clarity too. Focus is improved by absorbing reflections, however clarity is improved by maximizing the balance and relationship between focus and envelopment and clarity is the prime acoustical goal. Clarity is not focus, but focus does aid clarity. If you kill the echoes (reflections) you kill the resolution and information about space and locations. 

A lot of the same things that make a good music room also make a good theater room. Clarity, managed reflections, ideal RT60, smooth bass response, good seating locations, etc... 
By making a room sound better for movies you often make it sound better for music, and vice versa. There is always room for personal taste on envelopment vs focus, but you'll often find good rooms can do both music and movies.


----------



## asarose247

^
" multi-channel HT rooms should have more sound treatments and less reverb "

Is there any actual range of standards /decay times for what should be acceptable /desirable "less" reverb. 
a measurement of less -could that be as "simple" as a REW waterfall showing overall decay times?
how much time or a given range of time
would the same "time" be an good standard/ objective for (almost) any sized room? 

Reading REW threads etc. I get the impression that 300-500 ms. is a "good" area to shoot for, inititally.

Any good info, links, and we all learn . .

goes without saying that "more sound treatments" is as clearly defined as "boomy, punchy or flabby bass"


----------



## erwinfrombelgium

sdurani said:


> What part doesn't make sense? More speakers = more direct sound?


No, this: _Does being swamped by direct sound mean that reflected sounds are less noticeable?_

That would be like saying: If you only want a few red M&M's, it's nice if your mom removes the other colors for you. If you have a lot of M&M's then this doesn't matter anymore, it's too much work and you eat all the colors anyway?


----------



## erwinfrombelgium

asarose247 said:


> @erwinfrombelgium :
> Because of the Atmos speakers, I extended the diffusion all the way to ceiling height to make sure the ceiling speakers' first reflection points are tackled.
> 
> very interesting, considering the 23' wide room.
> 
> any treatment for the ATMOS speakers off axis ceiling reflection points
> 
> any links or pics?


The Atmos speakers will go where the gap in the absorption cloud is. Though 4 and not 6.


----------



## sdurani

erwinfrombelgium said:


> That would be like saying: If you only want a few red M&M's, it's nice if your mom removes the other colors for you. If you have a lot of M&M's then this doesn't matter anymore, it's too much work and you eat all the colors anyway?


Except in this case, the number of sources of direct sound (speakers) is changing. Same room, but you go from a 2-speaker stereo set-up to a 9.1.6 immersive set-up. You now have 15 sources of direct sound coming at you. Are reflections going to be more noticeable, less noticeable or the same? Will you hear the ceiling bounce of your front L/R speakers as clearly as before or will those reflections be drowned out by front height speakers? Will you hear early side wall reflections of your front L/R speakers as easily as you did before, or will they be harder to hear because of the wides?


----------



## erwinfrombelgium

AdvancedTheater said:


> Keep in mind reflections are good things, not bad things. You also don't need to worry as much about the stuff that does not hit your ears.


Some reflection might be good, but too much of a good thing...

Thing is, a lot will hit your ears. With 7.1 it is simple: most 1st reflections are in the narrow height window between speakers and ears. With Atmos, you need treatment higher up the wall as well.


----------



## erwinfrombelgium

sdurani said:


> Except in this case, the number of sources of direct sound (speakers) is changing. Same room, but you go from a 2-speaker stereo set-up to a 9.1.6 immersive set-up. You now have 15 sources of direct sound coming at you. Are reflections going to be more noticeable, less noticeable or the same? Will you hear the ceiling bounce of your front L/R speakers as clearly as before or will those reflections be drowned out by front height speakers? Will you hear early side wall reflections of your front L/R speakers as easily as you did before, or will they be harder to hear because of the wides?


I think it will all sound muddier without a fair amount of treatment.


----------



## sdurani

erwinfrombelgium said:


> I think it will all sound muddier without a fair amount of treatment.


More treatment than with a 2-speaker set-up? Keep in mind that when using only 2 speakers, the room is the surround processor. The question still stands: do you notice reflections more when using 2 speakers or 15 speakers?


----------



## asarose247

from a 2004 Dennis Erskine post: 
The reverberation time of .35 to 0.5 seconds is suggested for multi-channel playback systems. 

his reply to an RT60 range question (the spec I couldn't remember)

Still relevant for ATMOS?

It depends . .

Sanjay's question is a poser.

Fire up REW, try different configurations and see . . . 

and erwin isn't far of the mark:I think it will all sound muddier without a fair amount of treatment.

back to the drawing board


----------



## erwinfrombelgium

Fire up REW: that's indeed a very very good advice!


----------



## asarose247

wrt that .35-.5
lots of smart reading in the thread: what's the holy grail for rt60?

in the audio theory setup and chat section.

it's complicated.


----------



## Mashie Saldana

asarose247 said:


> and erwin isn't far of the mark:I think it will all sound muddier without a fair amount of treatment.
> 
> back to the drawing board


And that treatment, should it be absorption, diffusion or scattering?

Maybe we just need to cover all walls and ceiling with 2d BAD panels...


----------



## HopefulFred

sdurani said:


> ...does that fact that ambience is now coming from speakers around the listener rather than being added by the room (like in a 2-speaker set-up) mean less relying on reflections, so more absorption should be used?


As Erwin, this is my thought.



AdvancedTheater said:


> Keep in mind reflections are good things, not bad things. You also don't need to worry as much about the stuff that does not hit your ears. Start with the low hanging fruit and work your way up the tree, don't go get a ladder to pick your first one.


This is all true, but only conditionally, IMO, as the value of reflections relates to one of your other remarks.



AdvancedTheater said:


> Diffusion is often a good idea in the back half of the room. It aids envelopment, and can help make the localization of surround speakers less.


 Diffusion, as a variant of reflection, does change the perception of the location of sound sources. What's not universally true is that listeners want weaker localization. In my opinion, the whole reason for immersive audio is enhanced localization. While no one wants to hear their speakers - they want to hear the soundtrack - one shouldn't disregard the location information designed into the playback. If you only want to be vaguely aware of the source of any sound not in front of you, then a 5.1 system is more than adequate, lots of diffusion aids in that perception. On the other hand, if you want to allow the dynamic and precise work of modern soundtracks to be emphasized, I would suggest that absorption is more appropriate. The absorption should be employed to correct SBIR and to eliminate reflections from speakers on the opposite side of the room. If those two things are done, I expect RT to come down from a target of say 0.4 to 0.3 or 0.35. 

YMMV.


----------



## asarose247

my own simplistic (and undereducated?) approach was more absorption.

if that didn't seem to work, then add more.
under my SCATMOS cloud at the mlp, there is a very noticeable hushing just 6 or 7 feet into other areas of the room. Conversation is much clearer for me and people notice it right away.

does that make it better?

my cloud is 40 ft^2 of 5" thick inside about a 7' square.

anyway, more science, please


----------



## AdvancedTheater

asarose247 said:


> wrt that .35-.5
> lots of smart reading in the thread: what's the holy grail for rt60?
> 
> in the audio theory setup and chat section.
> 
> it's complicated.


Except RT60 in small rooms is unreliable measurement.


----------



## Lasalle

sdurani said:


> I always wondered about this. More speakers means more direct sound all around the listener. Does being swamped by direct sound mean that reflected sounds are less noticeable, so less absorption is needed? Or does that fact that ambience is now coming from speakers around the listener rather than being added by the room (like in a 2-speaker set-up) mean less relying on reflections, so more absorption should be used? I've heard valid arguments both ways.


I had a brief discussion at CEDIA on this with a couple of the JBL guys after their room calibration presentation. They had a lot of science behind stereo treatment, but indicated they have not done the level of studies multi-channel let alone immersive setups (Atmos.DTS:X,Auro). I believe the presenter's name was Sean. He thought more reflective with more diffusion vs absorption, but admitted he did not have the measurements to recomend it.


----------



## sdurani

Lasalle said:


> I had a brief discussion at CEDIA on this with a couple of the JBL guys after their room calibration presentation. They had a lot of science behind stereo treatment, but indicated they have not done the level of studies multi-channel let alone immersive setups (Atmos.DTS:X,Auro). I believe the presenter's name was Sean. He thought *more reflective* with more diffusion vs absorption, but admitted he did not have the measurements to recomend it.


Funny you should mention JBL. One of the times I heard arguments for needing less absorption when using more speakers was when I was taking a class at Harman. My pre-pro was from a Harman-owned company (Lexicon), whose surround processors shipped with a Theory & Design guide, which recommended the opposite: more speakers meant more absorption. Both made good cases for their point of view. Which is why I threw it out there as a question rather than coming down firmly either way.


----------



## AdvancedTheater

HopefulFred said:


> Diffusion, as a variant of reflection, does change the perception of the location of sound sources. What's not universally true is that listeners want weaker localization. In my opinion, the whole reason for immersive audio is enhanced localization. While no one wants to hear their speakers - they want to hear the soundtrack - one shouldn't disregard the location information designed into the playback. If you only want to be vaguely aware of the source of any sound not in front of you, then a 5.1 system is more than adequate, lots of diffusion aids in that perception. On the other hand, if you want to allow the dynamic and precise work of modern soundtracks to be emphasized, I would suggest that absorption is more appropriate. The absorption should be employed to correct SBIR and to eliminate reflections from speakers on the opposite side of the room. If those two things are done, I expect RT to come down from a target of say 0.4 to 0.3 or 0.35.
> 
> YMMV.


Hi Fred,

I would disagree on the localization part. You don't want localization, at least not in the sense you can pin point the speakers and where the sound is coming from. That takes away from the immersion and envelopment and realism, and it's often distracting. I have been in many theaters where the seats were located too close proximity to a speaker and it's pretty obvious how negative that effect is perceived. That problem is basically localization. Absorption in more or less quantity won't fix that problem either. You can reduce localization actually with less absorb and more diffuse which in the back half and around the surrounds can make them sort of disappear; but if the localization is due to an spl variation or close proximity that's a hard problem to fix without moving your seat or the speaker. 

Stereo sound has long been able to create a great image and 3D sound stage, for example with great placement and set up and quality speakers you can create the illusion of a phantom center or the illusion that there is a speaker between the two L and R speakers. Atmos tries to do that same thing, except now you can do it with not just the front L and R speakers, but any combination of any of the speakers. The technology does have a backing track where it uses ambient sound, but now with 3D sound they can layer in 3D audio objects which can be placed in 3D audio space inside your room. The point is not localization- you won't want that object to come from a specific speaker or channel in the traditional sense. You actually want that 3D audio object to render in 3D space, which if done correctly is actually not where you speakers are located rather where the mixers and artists wanted to put them. If they want you to localize the sound that is easy, juice up the mix to a single given speaker to make the sound come from that spot. But if they want to place the sound object somewhere else they need to use at least another speaker to do that. Localization is the opposite of what you want IMO. You want the sound to appear where it should be, and not sound like it's coming from a specific speaker. You should not realize where the speakers are, or the sound is coming from, when watching a movie. You should simply just hear it. Localization of the sound source can be distracting, at least to me. 

The issue is much smaller in commercial theater because the boundaries are farther away and you have a lot more space to work with. But in small rooms you have a lot less space so localization is a bigger problem. Unfortunately sometimes you make compromises because of the location and close proximity of the speakers in small rooms, and that is just the reality of the situation. However, I would suggest that is not ideal. A bigger room, less localization, and farther away sound sources and boundaries would generally yield a better result, and more specifically a better result for more than just a few seats. 

RT isn't a great measurement because it can change in a small room relative to mic location, or sound source. It won't be consistent enough in a small room to make a universal recommendation and just apply that. I wish it was as easy as that.


----------



## asarose247

What I could not review at the time was acoustic fields video, just to remind remind of what I'd read. Time to enjoy the recreational aspects of the HT beast.
Odd. Auto correct wanted to make that THC.
How did it know? The robots are taking over.
Run, Forest,RUN!


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## HopefulFred

AdvancedTheater said:


> You don't want localization, at least not in the sense you can pin point the speakers and where the sound is coming from.


Indeed. And from here it became clear to me that we (maybe just me?) have been sloppy in our word choice. Nobody wants localization when it comes to identifying a speaker as the sound source.

What many (though maybe not you?) do want, is precise imaging in the surround field. That's the term I should have been using in my post. As you described, immersive audio should be used to precisely locate phantom images all around. My understanding of the psychoacoustics and of the generally accepted use of mixing and mastering processes is that those characteristics of the soundtrack which make that precise imaging possible - the level balance, the delays, the phase shifts, etc. - are all set up within the mix. Natural acoustic effects which could be used to produce some of those same perceptions - the ones used to great effect in successful 2-channel environments - become detrimental when laid over the immersive multichannel mix.

There's room for personal preference here both for the listener and for the mixer, but my understanding of the industry is that for immersive soundtracks in movies and TV the mixer is anticipating a somewhat drier environment, and that the imaging in the mix is best preserved with more absorption.

As you suggested, there are plenty of reasons why you may not want that presentation - especially in a small room. Perhaps in a year or two we will have discovered that for most home users a near-field mix will require some sacrifices in image precision - especially for typical home listeners in non-dedicated spaces. Maybe even already I am behind in my understanding of the trends, but I think most mixers now are trying to use the software tools to see how far they can push the technology.


----------



## AdvancedTheater

Just copy the mastering room and you'll have what the artist intended


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## erwinfrombelgium

Atmos Mastering "room"

^ which mastering room? These come in all sizes and shapes...


----------



## johnnymacIII

*GIK Monster bass traps*

How many inches thick of insulation does GIK use in their monster bass trap and how much is an air gap? Thanks?


----------



## dnoonie

johnnymacIII said:


> How many inches thick of insulation does GIK use in their monster bass trap and how much is an air gap? Thanks?


Although their web site doesn't exactly specify, http://www.gikacoustics.com/product/gik-acoustics-monster-bass-trap-flexrange-technology/, "our thickest panel – 7.3125” thick", based on their test measurements and the test measurements of other treatment products I'd take a guess that it's 6" of insulation with a 1"gap, the extra 1/3 inch or so would be the back panel between the insulation and the gap/plenum.

Maybe someone can verify?

Cheers,


----------



## johnnymacIII

dnoonie said:


> Although their web site doesn't exactly specify, http://www.gikacoustics.com/product/gik-acoustics-monster-bass-trap-flexrange-technology/, "our thickest panel – 7.3125” thick", based on their test measurements and the test measurements of other treatment products I'd take a guess that it's 6" of insulation with a 1"gap, the extra 1/3 inch or so would be the back panel between the insulation and the gap/plenum.
> 
> Maybe someone can verify?
> 
> Cheers,


Your guess is right. I found this review. It's 6 inch insulation with an air gap at the back.

http://www.3daudioinc.com/3db/showthread.php?20588-GIK-Acoustic-Panels-a-review


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## AdvancedTheater

What's the effective frequency range of that product ?


----------



## Mashie Saldana

AdvancedTheater said:


> What's the effective frequency range of that product ?


All their test results are listed on their website.


----------



## JWL.GIK

Yes, that's all correct. Test data on the Monster traps are here:

http://www.gikacoustics.com/product/gik-acoustics-monster-bass-trap-flexrange-technology/

Scroll down and click the "Test Results" tab on the left. Note the nice bump at 80Hz, particularly with the Range Limiter installed.


----------



## arcticbowman

I'm framing in portions of my screen wall. I will be using an AT screen around 10' wide. All three walls behind the screen are ICF forms with 2" of foam. My thought is to attach something of this nature ---> https://www.amazon.com/gp/product/B01AB8JOV6/ref=ox_sc_mini_detail?ie=UTF8&psc=1&smid=A22SRM5AZO37HA for both looks and function since I will have some behind the screen lighting. 

For under the stage I was planning to install batted insulation below the plywood and possibly add an additional layer of plywood, or 2X4. On the sides we will be installing velvet curtains from floor to ceiling that will be for looks only, they won't pull shut to cover the screen. 3 Towers will be on the platform along with 2 15" subs between them. The framing on the right side is to line up the left and right angles of the turret. The "flaw" will be hidden behind the screen.

I'm a novice when it comes to acoustics, so I'm searching for some guidance here. Any insight would be appreciated.


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## erwinfrombelgium

As long as you don't think the shape of the foam has any beneficial influence on the sound.


----------



## Lesmor

In other words save your money


----------



## genesis_avs

For a room that has a large opening on one side (where some of the LCR first reflection points would be), do you treat the wall opposite of the opening with just absorption or is it still better to use combo panels (BAD/TAD)?

Please see my avatar for more detail.
1. In the *red* area do I just use absorption, or diffusion as well (BAD/TAD panels)?
2. If I put free-standing treatment in the *blue* area, should I put BAD/TAD panels there too?

*Green* area has absorption as follows: 2" on wall, 4" behind speakers, 6" corners.
*Yellow* area will have 2-4" BAD/TAD type panels that can be changed if needed.


----------



## Lesmor

genesis_avs said:


> For a room that has a large opening on one side (where some of the LCR first reflection points would be), do you treat the wall opposite of the opening with just absorption or is it still better to use combo panels (BAD/TAD)?
> 
> Please see my avatar for more detail.
> 1. In the *red* area do I just use absorption or diffusion as well (BAD/TAD panels)?
> 2. If I could put some free-standing treatment in the *blue* area, should I put BAD/TAD panels there too?
> 
> *Green* area has absorption as follows: 2" on wall, 4" directly behind speakers, 6" corners.
> *Yellow* area has 2-4" BAD/TAD type panels that can be changed if needed.


For good imaging and sound stage distances to a side wall from L/R speakers should be equal.
I imagine the open space at the Right speaker kind spoils this, also there would be no first reflection from the right speaker.
If it was me I would heavily treat the Left side wall to try and counter that.

Obviously too late but changing the layout might have been a better option i.e. L/C/R on the center of what is the left wall firing towards the open space


----------



## arcticbowman

erwinfrombelgium said:


> As long as you don't think the shape of the foam has any beneficial influence on the sound.


I mainly just like the look, but thought it would be advantageous if it provided some sort of functionality. Is there a better option?


----------



## Mashie Saldana

arcticbowman said:


> I mainly just like the look, but thought it would be advantageous if it provided some sort of functionality. Is there a better option?


It is very popular to either use two layers of 1" linacoustic or glass mineral wool behind the screen.


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## arcticbowman

I get that, but I'm working with a wall that isn't drywall or MDF, I'm working with a wall that has 2" of foam covering the concrete. I don't plan to put drywall on this wall if I don't have to. 


Would the foam from the ICF's create too much "treatment" as it stands? I'm hoping for some guidance in regards to possible acoustic benefits or issues I may have by leaving this wall alone or treating it somehow. If nothing else, I want it to look decent when I flip on the lights behind the screen, but I want to take advantage of any acoustical gains or prevent issues as much as possible at this stage.


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## erwinfrombelgium

Maybe you should invest more time reading about acoustics if you are serious about getting the best possible sound.

You want at least 4" of thickness or otherwise you only absorb high frequencies. The thicker the better. The most cost efficient way is to have a plenum of no more than the the thickness of the absorption. 4" fiberglass with 4" plenum is very, very good. I did 5" with 3" plenum on the ceiling (because 5" was a full pallet at a discount I could entirely use). Even mid-fi outdoor speakers sound excellent as I tested!


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## arcticbowman

Still not very helpful, but thanks anyway. I've got a game plan for the side walls, bass traps, etc. The question is regarding the ICF wall with the existing 2" of foam that is already in place on them. Will this much "softer" surface be an issue with the sound? Should I enhance the area with more absorption material, or cover it with drywall and start with the absorption material off of the solid surface?


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## dnoonie

Keep in mind that acoustic foam is about 1/2 as effective as the rigid fiberglass or rock wool that is in acoustic panels.

If you like acoustic foam consider getting at least 4" and/or even mixing some bass trap acoustic foam with the 4". Here's another place that has acoustic foam at a bit better price if you can wait, http://www.thefoamfactory.com/acousticfoam/wedgefoam.html, http://www.thefoamfactory.com/acousticfoam/bassbroad.html. I've ordered from them before, http://www.avsforum.com/forum/19-dedicated-theater-design-construction/255432-acoustical-treatments-master-thread-365.html#post36128410
(Link should scroll to post 10943, scroll down if it doesn't, although you might be interested in the discussion to that point)
There are anchor options that would let you attache rigid fiberglass or rock wool behind your screen, although it would look unfinished it could be covered with fabric.

I've used acoustic foam before and it's not as easy to make it look good as you might think, although with your new construction it might be easier. I've switched almost entirely to rock wool filled panels except for some acoustic foam bass traps in some areas where space is a concern.

Were you planing on gluing the acoustic foam into place?

Cheers,


----------



## Lesmor

arcticbowman said:


> Still not very helpful, but thanks anyway. I've got a game plan for the side walls, bass traps, etc. The question is regarding the ICF wall with the existing 2" of foam that is already in place on them. Will this much "softer" surface be an issue with the sound? Should I enhance the area with more absorption material, or cover it with drywall and start with the absorption material off of the solid surface?


With respect "Still not very helpful" is a bit of an insult to those who have given good advice.
It seems "You've got a game plan" good luck with that


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## arcticbowman

Lesmor said:


> With respect "Still not very helpful" is a bit of an insult to those who have given good advice.
> It seems "You've got a game plan" good luck with that


I guess it depends on how easily offended you get? I appreciate the information provided, most of which I "mostly" understand after reading quite a bit here and other sources. I haven't found much info on the ICF walls adding any benefit or causing any issues if left untreated with a solid surface, which is what my main question is. No disrespect intended, and as mentioned, I do appreciate the information.


----------



## Lesmor

arcticbowman said:


> I guess it depends on how easily offended you get? I appreciate the information provided, most of which I "mostly" understand after reading quite a bit here and other sources. I haven't found much info on the ICF walls adding any benefit or causing any issues if left untreated with a solid surface, which is what my main question is. No disrespect intended, and as mentioned, I do appreciate the information.


Your main concern should be in treating *S*peaker *B*oundary *I*nterferance *R*esponse behind your L/C/R

Also although visually it will look nice having both subs between the L/R might not give the best frequency response.
Only by doing some measurements will confirm.


----------



## arcticbowman

Thank you for the reply. I'd like to go minimal behind the screen against the ICF wall to leave as much room as possible for the speakers. I'll be ordering up some acoustic panels for the rest of the theater, but I can wait for those. Because of where I'm at, Roxul Safe and Sound is about the only option without waiting or paying shipping, but I don't want to fight with it to try and make panels out of it.

For the foam, I could either use the existing black nailer strips, which are 8" apart to hold them in place, or frame in deep enough to install Roxul and use the boards to attach the acoustic foam to. I was hoping I wouldn't need the Roxul because the foam from the ICF's would work with the acoustic foam enough, which was my main focus of the question. I really like the option of the 4'X6' size for the foam, but I would like to go with something that has a little better appearance when I light it up behind the screen. I picked up a bag of the Roxul today to frame in the corners right in front of the screen, but this gives me a chance to play with some behind the screen.



dnoonie said:


> Keep in mind that acoustic foam is about 1/2 as effective as the rigid fiberglass or rock wool that is in acoustic panels.
> 
> If you like acoustic foam consider getting at least 4" and/or even mixing some bass trap acoustic foam with the 4". Here's another place that has acoustic foam at a bit better price if you can wait, http://www.thefoamfactory.com/acousticfoam/wedgefoam.html, http://www.thefoamfactory.com/acousticfoam/bassbroad.html. I've ordered from them before, http://www.avsforum.com/forum/19-dedicated-theater-design-construction/255432-acoustical-treatments-master-thread-365.html#post36128410
> (Link should scroll to post 10943, scroll down if it doesn't, although you might be interested in the discussion to that point)
> There are anchor options that would let you attache rigid fiberglass or rock wool behind your screen, although it would look unfinished it could be covered with fabric.
> 
> I've used acoustic foam before and it's not as easy to make it look good as you might think, although with your new construction it might be easier. I've switched almost entirely to rock wool filled panels except for some acoustic foam bass traps in some areas where space is a concern.
> 
> Were you planing on gluing the acoustic foam into place?
> 
> Cheers,


----------



## arcticbowman

Lesmor said:


> Your main concern should be in treating *S*peaker *B*oundary *I*nterferance *R*esponse behind your L/C/R
> 
> Also although visually it will look nice having both subs between the L/R might not give the best frequency response.
> Only by doing some measurements will confirm.


I am leaving myself some options for sub placement in the future. I'm installing a couple of wall outlets for sub cables on the side and rear of the room.


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## CherylJosie

HopefulFred said:


> ...There's room for personal preference here both for the listener and for the mixer, but my understanding of the industry is that for immersive soundtracks in movies and TV the mixer is anticipating a somewhat drier environment, and that the imaging in the mix is best preserved with more absorption.


The early reflections off room boundaries turn the multi-channel acoustic environment into a 'house of mirrors' that, if actually constructed of mirrors, would visibly as well as acoustically multiply the number of sound sources in the room until they all just blend into a mishmash of intermingled splashes that destroy the 3D sonic effect.

What we are coming to grips with is physics, not preference.



> As you suggested, there are plenty of reasons why you may not want that presentation - especially in a small room. Perhaps in a year or two we will have discovered that for most home users a near-field mix will require some sacrifices in image precision - especially for typical home listeners in non-dedicated spaces.


Not sure what 'sacrifices' you are referring to, or whether they are being made at the recording end or the playback end.

I discovered that achieving a full 6" depth of reflection panel absorption puts the absorption so far out into a small space (relative to the overall room dimensions) that it intersects a substantial amount of the ambient energy with those life-giving late reflections. I left the absorption open around the edges and suspended off the walls slightly to try and extend its bandwidth as much as possible, but decided to change to surface mount with hard frame borders instead to preserve as many later reflections as possible.

Also, when building for a small space, standard sized prefab absorption treatments are all guaranteed to be either just a little too large or a little too small on one or more dimensions.

Plus, without a workshop or garage, the possibility of building silica based absorption without contaminating the entire living space with mineral dust or sawdust is just about zero, as is the possibility of anchoring anything to the ceiling without causing a storm of acoustic spray dust to come falling in.

So my approach was to skin the cheapest fluffiest largest polyethylene fiber pillows I could find. No cutting of fiberglass and no silica contamination, and at the sizes required for a small space, the cost is reasonable. I added a couple of spare polyethylene fiber sofa cushions to the ceiling absorber as well since they were free.

It seems to work OK, but I did notice that if the pillows are overstuffed type, or compressed from use, they become denser and do not work as well as the cheapest fluffiest marshmallow types bought new.



Lesmor said:


> Your main concern should be in treating *S*peaker *B*oundary *I*nterferance *R*esponse behind your L/C/R


That is difficult in a small space. Adding any absorption at all to the front wall soaks up what little later ambiance remains and contributes even more nothingness to that overly dead sound.



> Also although visually it will look nice having both subs between the L/R might not give the best frequency response.
> Only by doing some measurements will confirm.


I ended up with one subwoofer at ear level pointing into the deepest front corner farthest from any discontinuous boundaries where the low end is strong and smooth, but also centered floor-ceiling to drive that mode from a null. The other is across the room under the dining table sideways at the center of the wall where the upper end of the sub range had more output.

Although the subwoofer frequency response is finally near target I still have a 5dB broad peak at 20Hz just below a broad modal gap near 30Hz that sets the 'floor'. Fortunately the peak is not so audible that far toward the lower end of the frequency range, but such a peak does nothing to enhance apartment listening where I am trying not to rattle my neighbor's dishes.

I also found that it was difficult to maintain the top end of the subwoofer output when placing and tuning them for the smoothest response at the MLP. The amplitude and phase go wrong at 80Hz when the pass band below is smooth. It took me a while to get the phase flat up to 90Hz for better crossover integration but there is still too much amplitude ripple.

I was contemplating adding a third subwoofer in the one remaining sweet spot on the ceiling over the center speaker (determined by subwoofer crawl using REW) but I scrapped the idea eventually as too difficult to handle from the installation standpoint and just resigned myself to ho-hum crossover integration, particularly on the surrounds that need substantially higher crossovers.



dnoonie said:


> Keep in mind that acoustic foam is about 1/2 as effective as the rigid fiberglass or rock wool that is in acoustic panels.


Do you have an estimate of the effectiveness of polyethylene fiber as used in pillows and cushions, compared to glass or rock? My initial experiments indicate that it seems to 'sound' pretty good, provided the fiber is removed from its casing.

I did add a 20x24x30 corner chunk of fiberglass in an open frame under the elevated subwoofer, wrapped in kraft paper and then wrapped in a cloth cover, to try and tame that 20Hz some as well as smooth the higher subwoofer frequencies a little. It seemed to help slightly, but I am now contemplating adding a resonant trap of some sort.

Going to have to find a recipe for that. I was thinking tube trap for simplicity, or maybe two or three of them, but I need some way of calculating the tuning and surface area of the opening required for the attenuation I am looking for. I need to trap between about 18Hz and 25Hz. What are the chances I can fit such a trap into my space? 8' of 8" sonotube on the ceiling? Links anyone?

Also, I am still trying to figure out the covering for the absorption. I would rather not use cheese cloth. I was thinking milliskin spandex for the acoustic transparency and the look. The ceiling absorber is going to be matte black to tame projection reflected light and I would rather not have it also look cheap. For a living room, it already looks depressingly theater-ish with all that black paper pinned to the front wall catching the acoustically transparent screen light spilling through.

The challenges of doing this tuning in a small space are really extraordinary. I read posts about dedicated theaters and see REW plots and I can only shake my head. When trying to fit similar technology into a small space like mine, the laws of physics get in the way.


----------



## Mashie Saldana

CherylJosie said:


> The challenges of doing this tuning in a small space are really extraordinary. I read posts about dedicated theaters and see REW plots and I can only shake my head. When trying to fit similar technology into a small space like mine, the laws of physics get in the way.


What size is your room?


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## CherylJosie

Mashie Saldana said:


> What size is your room?


Larger than yours, apparently.

edit: 14' was wrong. The front-rear is 12'.

Overall dimensions are 12'x25' but there is a pantry protruding into the space so it is more approximately 12'x20', except it has irregular boundaries including a short hallway and the overall outline of the floorplan is squarish with the bedroom in the corner shortening the front-back dimension of the living room.

The only symmetrical dimension is floor-ceiling (no stairways etc) so that is why one subwoofer ended up on a stand to drive from a null. It was the only way to get smooth frequency response in the bottom end without inducing deep nulls in the top end.

I discovered that opening all the drawers and cupboards in the kitchen helps de-tune some modal resonance, whereas opening the bathroom or pantry makes it worse. Opening the bedroom helps tame the 20Hz slightly but it also deepens the modal gap at 30Hz.

I should post some pictures and drawings of the current installation but it is not finished yet and I would rather get current measurements. I suspect things need tuning again once the absorption is complete and I am still hoping to add some diffusion eventually.

Besides the learning curve I am also physically challenged by this installation so it is going slowly, but the help I got on the forum made all the difference getting set up.

The system is currently 11.1, but I am tentatively planning to upgrade to 9.2.4 eventually, provided I stay here long enough to justify the work and investment.


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## BondDonBond

I first want to say you guys on here know your craft! I have been reading the form for awhile now. I am going to ask a question which has been somewhat asked but want to maybe ask a little different and be sure I am not going crazy.

Thoughts on Theater Acoustics seems to be almost as divisive as our political system God forbid. Great science behind it and am convinced that for most here it is go big or go home and they are right....but. You look here and you get one answer and you look at other forums and you get something different.

There is this whole thought out there that with Atmos etc you should really only treat the ceiling and floor and leave the rest alone. Others say make the room as dead as possible. I know it is preference and I plan on experimenting with it but want to see what others think.

If you were to put in order the order in which to treat an average basement room with walls on all sides what would it be? Ceiling, Floor, Front wall, Back Wall, Side wall, First reflections....my head is spinning. Where would your start the experiment and then keep adding and taking away?

For reference my system is:
B&W Nautalus 802's, HTM1, 4-805's for surround with 4- Harmon 22's in ceiling for Atmos and Marantz 8802a, MacIntosh 8207 Amp and Proceed Amp 5 with Oppo 203.

This room is for movies not music. is 16X26 with 8' ceilings.

Thanks!


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## ereed

BondDonBond said:


> I first want to say you guys on here know your craft! I have been reading the form for awhile now. I am going to ask a question which has been somewhat asked but want to maybe ask a little different and be sure I am not going crazy.
> 
> Thoughts on Theater Acoustics seems to be almost as divisive as our political system God forbid. Great science behind it and am convinced that for most here it is go big or go home and they are right....but. You look here and you get one answer and you look at other forums and you get something different.
> 
> There is this whole thought out there that with Atmos etc you should really only treat the ceiling and floor and leave the rest alone. Others say make the room as dead as possible. I know it is preference and I plan on experimenting with it but want to see what others think.
> 
> If you were to put in order the order in which to treat an average basement room with walls on all sides what would it be? Ceiling, Floor, Front wall, Back Wall, Side wall, First reflections....my head is spinning. Where would your start the experiment and then keep adding and taking away?
> 
> For reference my system is:
> B&W Nautalus 802's, HTM1, 4-805's for surround with 4- Harmon 22's in ceiling for Atmos and Marantz 8802a, MacIntosh 8207 Amp and Proceed Amp 5 with Oppo 203.
> 
> This room is for movies not music. is 16X26 with 8' ceilings.
> 
> Thanks!


You may want to do bass traps and first reflection points first and then go from there. Nice equipment by the way.....and to get the most out of it you are at the right place. 

Its always good to have a mix of absorption and diffusion. You don't want the room completely dead nor too alive.


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## BondDonBond

ereed said:


> You may want to do bass traps and first reflection points first and then go from there. Nice equipment by the way.....and to get the most out of it you are at the right place.
> 
> Its always good to have a mix of absorption and diffusion. You don't want the room completely dead nor too alive.


Thanks, that helps. On one side of the room I have a column that houses one of the side 805's and it is 15"X17" and I filled it with Roxul sound and sleep and covered with cloth. I also have a across the center of the room a 10"deepX50"wide bulkhead that I put 4" of Roxul in and covered with cloth. On Friday I get 18 sheets of Roxul Rockboard that I am going to use for 4 on one side of the bulkhead and 3 on the other on the ceiling acoustic panels and then have the rest for something else like wall panels. I am putting in two 16"x16"X64" rear columns to put my rear 805's on and this is one question, fill it with sound and sleep or Rockboard? and then cover with cloth. I need to get a good pad for the carpet on the floor.

Oh, forgot the mention I have 2- 18" Velodyn subs- the old but good ones. one in front and on on side.

Soooo, then comes the big question, I have good equipment and a pretty good ear. If it sounds good and not too boomy etc do I just say all is good or should I get a mic and software and test the room?

I can see where you can get sucked into this and never stop. Do they have support groups for Acoustical Treatments Anonymous?


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## CherylJosie

BondDonBond said:


> ...I have good equipment and a pretty good ear. If it sounds good and not too boomy etc do I just say all is good or should I get a mic and software and test the room?


I found that I had no idea what good sound was until I started improving my system and learned to recognize actual improvements versus just change.

Typically, the engineer in me says measure the acoustics before you do anything, and re-measure after you do anything for comparison.

Of course I violated my own rule because of the labor involved in learning to manage acoustics.

Your first install is going to be an experiment in your own competence to manage acoustics. If you want to know for sure that the treatments you are installing are actually helping and not making things worse, you should do before and after measurements on every change.

By the time you learn the tools well enough to take measurements and interpret them, you will probably wish you did things differently.

So if you have an itch to optimize the sound you should resign yourself to measuring everything throughout the process and re-doing some of the work later after you learn how to measure properly.

This learning curve is why people tend to hire experts to help them with their installation. It can save costly mistakes.

Your room is large enough that you should be able to control early reflections and modal resonances without overly deadening the sound. You should also be able to use diffusion to preserve ambiance while controlling early reflections because there is enough distance from the diffusion to take advantage of the inverse fourth power distance law (specular i.e. reflections off a planar surface only attenuate on inverse square law like direct sound does).

Ideally you just know by rule of thumb and experience, but like me, you just starting out. Expect to make mistakes and expect to need measurements to fix them. This all said by person who is still learning. For what it is worth.


----------



## ereed

BondDonBond said:


> Thanks, that helps. On one side of the room I have a column that houses one of the side 805's and it is 15"X17" and I filled it with Roxul sound and sleep and covered with cloth. I also have a across the center of the room a 10"deepX50"wide bulkhead that I put 4" of Roxul in and covered with cloth. On Friday I get 18 sheets of Roxul Rockboard that I am going to use for 4 on one side of the bulkhead and 3 on the other on the ceiling acoustic panels and then have the rest for something else like wall panels. I am putting in two 16"x16"X64" rear columns to put my rear 805's on and this is one question, fill it with sound and sleep or Rockboard? and then cover with cloth. I need to get a good pad for the carpet on the floor.
> 
> Oh, forgot the mention I have 2- 18" Velodyn subs- the old but good ones. one in front and on on side.
> 
> Soooo, then comes the big question, I have good equipment and a pretty good ear. If it sounds good and not too boomy etc do I just say all is good or should I get a mic and software and test the room?
> 
> I can see where you can get sucked into this and never stop. Do they have support groups for Acoustical Treatments Anonymous?


You probably don't need alot of room treatments. It all depends on the room itself. Even though you like the way your system sounds the point of room treatments is just to get better imaging, wider soundstage, tighter bass and improved decay times of bass, etc. So treating the room just gets that extra edge of your equipment. 

In my setup since its in open floor plan living room and I sit almost up against the rear wall I just use bass traps on rear wall since thats where the bass builds up and also absorbs sound so it doesn't reflect back to my head after the sound passes my head from front speakers. Also I did combination of diffusion/absorption panels on first reflection points on side wall. Just 6 panels alone made a big difference and really made the room look better as well since I needed artwork/pictures on wall and it was nice using acoustic panels instead.


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## BondDonBond

Thank you both for the feedback, much appreciated.

Does anyone have suggestions on PC software for testing the room?


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## erwinfrombelgium

Rew


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## 12B4A

Completely filling a closet with insulation

Would anyone like to offer an opinion on this idea? My room is approx. 10'x15'x8' with a closet that extends out in to the room (making the room an irregular shape of 10'x12'x8' with notch to 15' where the closet isn't jutting out). It's internal dimensions are 5'x2'x8'. With a quick check of some bass range pink noise and SPL meter, the folding doors to the closet do next to nothing for affecting the bass so I figure I can keep them on. After doing some searches, it _seems_ like this is a relatively inexpensive, ridiculously simple install that would provide a significant performance change. 

I run in to a few unknowns about this idea though. It seems that when implementing larger volumes of absorption, using a less dense insulation is preferred. It's unclear to me if this is for end result performance or cost vs. performance and installation ease.
It also seems like Roxul and Ultratouch are preferred nowadays especially if you're not going to be thorough with covering the insulation. Are there secondary concerns about this like bugs or fumes?


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## drunkpenguin

Seems like a waste of a closet to me. Why not knock down the walls and get rid of it if your not going to use it?


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## 12B4A

Condo...


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## Drelldrell

12B4A said:


> Completely filling a closet with insulation
> 
> Would anyone like to offer an opinion on this idea? My room is approx. 10'x15'x8' with a closet that extends out in to the room (making the room an irregular shape of 10'x12'x8' with notch to 15' where the closet isn't jutting out). It's internal dimensions are 5'x2'x8'. With a quick check of some bass range pink noise and SPL meter, the folding doors to the closet do next to nothing for affecting the bass so I figure I can keep them on. After doing some searches, it _seems_ like this is a relatively inexpensive, ridiculously simple install that would provide a significant performance change.
> 
> I run in to a few unknowns about this idea though. It seems that when implementing larger volumes of absorption, using a less dense insulation is preferred. It's unclear to me if this is for end result performance or cost vs. performance and installation ease.
> It also seems like Roxul and Ultratouch are preferred nowadays especially if you're not going to be thorough with covering the insulation. Are there secondary concerns about this like bugs or fumes?


I had the same idea about a week ago and worked very well for me.

My family room/home theater space is 11x23x7 with a 11x3x7 closet on the left side. There is a set of hollow-core french doors on the closet, which also has my water meter and someday will become an audio cabinet. The closet was insane with bass that seemed like it boomed and resonated out into the main room. For some reason it took me three years to realize this. Based on a ton of research online, I bought six bags of Green Fiber low dust blow-in insulation at home depot for about $6 a bag. Stacked three in each front and back corner (on the main room side of closet) on a diagonal to create an air void. 

Crude, but effective - the bass peaks in the closet are gone. Significant difference. The bass in the main room is much tamer as well. In fact, the bass is much less boomy for music (a bit disappointing, but likely a more accurate sound representation) and more clear/crisp for movies. I have a six or seven year old Elemental Designs A5-300 subwoofer that I am now less impressed with after upgrading the AVR, adding Atmos speakers, and adding more acoustic treatments. I am getting better sound/imaging at lower volumes - treating the wall immediately behind the wall mounted screen had the most incremental improvement next to the insulation. 

I'd give it a try. Worse case you take the insulation back for a refund. Better case, you have better bass in listening area for a cheap cost. I also bought cotton laundry bags to place the bags of insulation into. I did not open the bags. The fairly thin plastic packaging has not effect a the low end levels - IMO.


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## RapalloAV

Would some of you guys make comment on this drawing I have of the area behind my AT screen. Do you think the acoustic rookwool treatment on the front wall behind the speakers is adequate not?
Would you have thicker?


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## marius

*Challenge with sliding glass door*

Acoustic treatment newbie here.

The sliding glass door is the type with blinds between the two window panes, so I don't think I can convince my wife to put heavy drapes over it. There are two reflection points that I can see: 1) near right edge of sliding door for the tower (seen in pic), and 2) near left edge of sliding door for the center channel.

Any ideas from experts?

(see attached pic)


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## 12B4A

Drelldrell said:


> I had the same idea about a week ago and worked very well for me.


Nice! That's a good idea creating an air void. What are the dimensions of the GreenFiber bags? I can't seem to find that particular info online.


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## Drelldrell

12B4A said:


> Nice! That's a good idea creating an air void. What are the dimensions of the GreenFiber bags? I can't seem to find that particular info online.


http://www.homedepot.com/p/GreenFib...w-in-Insulation-19-lbs-Bag-INS541LD/100318635


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## 12B4A

Wow, how did I not see that before? Thanks!


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## BllDo

marius said:


> Acoustic treatment newbie here.
> 
> The sliding glass door is the type with blinds between the two window panes, so I don't think I can convince my wife to put heavy drapes over it. There are two reflection points that I can see: 1) near right edge of sliding door for the tower (seen in pic), and 2) near left edge of sliding door for the center channel.
> 
> Any ideas from experts?
> 
> (see attached pic)


If you're handy, you could make something like the below pic. You could even put it on wheels to slide out of the way when not in use. 









Source


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## austin85

^^ +1. GIK (I'm sure others) make freestanding panels as well.


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## BondDonBond

erwinfrombelgium said:


> Rew


Thanks for the referral on this. Setting it up tonight and running it. Can't wait to see how screwed up the room is.


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## Nick V

I posted this in the Audio Theory, Setup and Chat area, but maybe this is a better place for it:

I'm surprised this doesn't come up more often...

My main system does double duty for music listening and tv/movie viewing.

I have a fairly large 70" flat panel that is directly above and in between my KEF LS50 speakers, mounted on the wall. 

For TV/movies this is obviously a necessary evil. However, for music listening I want to put together an acoustic panel that I can put over the TV to cover it while listening to music. I think this would significantly improve the sound of the system for 2 channel music.

I was thinking of taking a 5' x 3' (size of the TV) sheet of thin plywood or stiff foam board, wrapping the back side with velour (so it doesn't damage the tv screen) and glue diffusers or absorptive tiles to the front side. Then staple some short pieces of bungee cord to the top left and right corners to wrap around the top corners and secure the panel to the TV. Has anyone done this?

I was thinking of using these: Auralex GeoFusor11 

They're 1' x 1' x 4.25" so I can just glue 3 rows of 5 to the front of the panel and that's the exact size of the TV.

I was also considering the Vicoustic Multifuser DC2 but they're quite expensive and the size doesn't match up properly so I'd have to cut some of the panels in half to fit. Does anyone know of any 1' x 1' skyline style polystyrene diffusers at a reasonable price?

Any thought on whether absorption or diffusion is the way to go here? 

In this room I already have 2x GIK 242 absorptive panels directly behind the speakers, 2x GIK 242 Panels at the first reflection points on the side walls, 2x GIK Tri-Traps in the rear corners of the room, 1 GIK monster bass trap behind the couch at the mid point on the rear wall and 2x GIK Art panels behind the MLP. That's why I'm thinking diffusion is the way to go in between the speakers.

Thoughts or Suggestions?

Or would something MUCH less expensive like this suffice?


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## ctviggen

If you're looking for diffusion, the only one that seems reasonable to me is the DC2. I don't think you're going to get much diffusion with the others. Diffusion has a number of factors, but anytime you have a large pattern that repeats, you're going to have limited diffusion. That's why the DC2 works -- it's got a small pattern, meaning more diffusion (where "more diffusion" means over a wider frequency band). 

Personally, what I did was have some thin (2 inch I think) realtraps that were on stands, similar to the ones described a few posts above. Post 11715. I then put these to the inner sides of the speakers, where inner means points towards the TV/flatscreen, and basically perpendicular to my seat. This helped a ton. When I was not listening to two channel, I would move the realtraps out of the way.

At a minimum, get a blanket and drape it over the TV. Does that help?


----------



## BondDonBond

I am building my own acoustical panels out of Roxul Rockboard. Question I have is for the frame, any thoughts on wood vs PVC boards? Or is there something else I should use?

Thanks for your help.


----------



## rabident

Nick V said:


> I was also considering the Vicoustic Multifuser DC2 but they're quite expensive and the size doesn't match up properly so I'd have to cut some of the panels in half to fit. Does anyone know of any 1' x 1' skyline style polystyrene diffusers at a reasonable price?


Supposedly Vic is out of business in the US and RPG lead times have gone from weeks to months, although my local dealer said the latter is nothing new. That's 2nd hand info, curious myself if that's been confirmed. 

I don't think Skylines are available as 1' x 1'. The Aurlex Geofusors were the only 1' x 1' min 4" diffusors I could find (Nyal suggested them). I couldn't even find commercial 1' x 1' x 4" absorbers, but those are easy enough to DIY.

I need a replacement for the Multifuser DC2's if they are no longer available. I don't want to have to do a drop ceiling. I wanted something I could glue to drywall. But I don't think drywall will support 64sqft of wood diffusors. So the plan was to use polystyrene, either DC2 (1st choice because they are cheap) or RPG Skylines... but now I need something that will work as a substitute.

I didn't realize Quest AI had 4" panels (otherwise I assume they would have spec'd them for my room). But I'm curious how they perform since they would be lightweight and presumably easy to mount on the ceiling over a large surface area.

Worst case, I can just put my order in for RPG and wait however long it takes. Any suggestions?


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## denonsix

Looking for some room advice...
I have an 18'L x 14'W x 10'H 7.1 room with two rows of seats...

I'm planning to put OC703 floor-to-ceiling 24"x17"x17" superchunk bass traps in every corner.

I'm also planning on building OC703 absorption panels for the first reflections.
What i'm having issues with is the width of the panels. With a 14' wide room the side wall space is at a premium and not sure I want to double up the OC703 and take up 4-5" of space (if I treat every seat for both rows, 8 seats total).
Is 2" sufficient for OC703 for absorption panels around the room if I already have corner bass traps? or am I going to be sacrificing too much in sound quality?
I could also look at 2" with a 4" frame (1.5" air gap)...or just treat the front row 'prime seat' reflections with 4" 703.
I have room height, so i'm going to treat ceiling reflections at both rows with 4" 703 and a bit of a gap there.

Any suggestions in regards to the comments above?

Thanks in advance for any help!


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## drunkpenguin

Will treating the ceiling for first reflection points make a wow difference if the rest of the room is already treated pretty good? I have 4 panels left over that are not being used and I'm considering putting them on the ceiling. They are the typical 2'x4' 2" panels.

My ceilings are 10' tall so is that still a needed reflection point or is it high enough to not be as bothersome as a lower ceiling might be? I hate to go through all this work if it doesn't help much. Any thoughts?


----------



## ereed

drunkpenguin said:


> Will treating the ceiling for first reflection points make a wow difference if the rest of the room is already treated pretty good? I have 4 panels left over that are not being used and I'm considering putting them on the ceiling. They are the typical 2'x4' 2" panels.
> 
> My ceilings are 10' tall so is that still a needed reflection point or is it high enough to not be as bothersome as a lower ceiling might be? I hate to go through all this work if it doesn't help much. Any thoughts?


Any sound that reflects back to you should be treated. Treating some areas are better than none, but treating all first reflection points are best. That includes ceiling, floor, side walls, rear wall behind you. If you don't want to do ceilings and are happy with sound then leave it alone....but treating it does help even more if you want to spend time putting panels there.


----------



## drunkpenguin

Since i have them i guess ill try it. Im going to hang with eye hooks and chains. If i put 4 hooks on the panel and 2 on the ceiling will they hang level? Or should i use 4 hooks on the ceiling?


----------



## ereed

drunkpenguin said:


> Since i have them i guess ill try it. Im going to hang with eye hooks and chains. If i put 4 hooks on the panel and 2 on the ceiling will they hang level? Or should i use 4 hooks on the ceiling?


Use whatever you need to hang it as long as it supports the weight. Usually ceiling first reflection points are about halfway between you and the speakers but use mirror test to make sure. It doesn't matter if its flush to ceiling or few inches gap, as long as the panel is where you see the tweeter/mid from your main listening position. You want to do the mirror test with all 3 LCR speakers or LR speakers at least from MLP. Got pics of your room?


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## drunkpenguin

I recently redid the room. I used to have floor to ceiling treatment on the front wall but took it down in favor of looks. It brightened up the room some and I like it better, but I'm thinking ceiling treatment might help more since I have less absorption than I used to, and since this hobby never really ends why not?


----------



## ereed

drunkpenguin said:


> I recently redid the room. I used to have floor to ceiling treatment on the front wall but took it down in favor of looks. It brightened up the room some and I like it better, but I'm thinking ceiling treatment might help more since I have less absorption than I used to, and since this hobby never really ends why not?


Nice room and setup! If you prefer more lively and feel that absorption panels deadens the room too much then maybe look at diffusion panels instead so it scatters the sound rather than absorbing it. Even I have absorption/diffuser panels on my first reflection points to make the room feel larger. It absorbs some frequencies and scatters some frequencies at the same time.


----------



## drunkpenguin

I've considered diffusion, but they cost too much! Some day I might try to build some if I ever get properly motivated. My room is all trial and error. I don't try to tackle it from a science perspective like using REW. I just try things to see what works. Like the panels in the back of the room. That happened by accident because I wanted to hide the speaker cables from the surrounds. Putting panels back there seems to go against the norm, but for some reason it brings the base of the sub into the center of the room much better! So they stayed.


----------



## 12B4A

One thing you could try is modifying your absorption panels with BAD-style diffusers as exampled here: http://www.avsforum.com/forum/155-diy-speakers-subs/1312919-diy-sound-diffusers-11.html#post26369905

1/8" hardboard is ~$6 per 8'x4' sheet. Cutting the right holes in in might be a chore unless you know someone with a CNC machine for wood.


----------



## drunkpenguin

12B4A said:


> One thing you could try is modifying your absorption panels with BAD-style diffusers as exampled here: http://www.avsforum.com/forum/155-diy-speakers-subs/1312919-diy-sound-diffusers-11.html#post26369905
> 
> 1/8" hardboard is ~$6 per 8'x4' sheet. Cutting the right holes in in might be a chore unless you know someone with a CNC machine for wood.


THats a thought! I like the design. I'll have to read up on those "bad" boys.


----------



## ereed

Or you could do something like GIK alpha panels which are absorption panels with wood slats in front of it that does the diffusion part. Make regular panels and get some 1/8 inch wood with vertical slats and glue to front of panel. But I recommend talking to GIK to see what they say about their advice on what you should do. Its free service and you don't have to actually purchase anything.


----------



## thecloneranger

hi i have a small game/ theatre room i would like to treat since ive been reading on the importance of properly treated room. and since i have quite a bit of money invested i wanna do this before upgrading anymore. any way ill include a pic of my room and maybe i can get some suggestions are where to start. i have a umik coming in this week so i can started on rew. but just wanna get some ideas from you guys. for example i want to treat the ceilng and the walls were speakers are at maybe some bass traps for the corners. any help would be appreciated thanks.


----------



## ereed

thecloneranger said:


> hi i have a small game/ theatre room i would like to treat since ive been reading on the importance of properly treated room. and since i have quite a bit of money invested i wanna do this before upgrading anymore. any way ill include a pic of my room and maybe i can get some suggestions are where to start. i have a umik coming in this week so i can started on rew. but just wanna get some ideas from you guys. for example i want to treat the ceilng and the walls were speakers are at maybe some bass traps for the corners. any help would be appreciated thanks.


With those 3 subs you will have alot of bass buildup in the corners so start with corner bass traps first. Floor to ceiling is optimal and do all corners if you can. This will absorb low frequencies that is bouncing around in the corners and then bounce back around in the room, the traps will absorb it so resulting in tighter, cleaner bass with improved decay. I see your wall art....are they acoustic panels? If not, you can get acoustic panels with same art work you have if you want to keep same theme in the room.


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## thecloneranger

alright thanks for the advice. i will definetly start there


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## jhermsmeyer

*Treatments & Calibration Sanity Check Request*

I was hoping someone could take a quick look at the following post, and let me know if I am doing anything silly.

The post contains pics of my treatments and a bunch of measurements. 

Interior Room Dimensions:
Length: 21’ 9”
Width: 15’ 3”
Height: 8’ 10”

*post link*

thanks!


----------



## thecloneranger

ereed said:


> With those 3 subs you will have alot of bass buildup in the corners so start with corner bass traps first. Floor to ceiling is optimal and do all corners if you can. This will absorb low frequencies that is bouncing around in the corners and then bounce back around in the room, the traps will absorb it so resulting in tighter, cleaner bass with improved decay. I see your wall art....are they acoustic panels? If not, you can get acoustic panels with same art work you have if you want to keep same theme in the room.


 the art work is canvas shouldnt that be good acoustics or would it be better to have real acoustic panels?


----------



## arcticbowman

I've got two questions. I'm looking to treat about 40-45% of the walls/ceilings and need to see how I should factor in these two features of my home theater.

1) I have a 6'X10'star ceiling going up. I made the ceiling with 1&1/2" insulated foam board and polyester fabric. Will this be a sound absorbing area?

2) I am planning to install two columns on the side walls and a majority of the rear wall out of faux rock. Can the faux rock be considered diffusion material, or will it act more like a solid surface? 

I posted a couple of pictures for reference. This probably won't be the rock we will choose, but it will be something of this nature.


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## HopefulFred

Everything could be said to be absorptive, reflective, and diffusive at some frequencies and to some extent; however, for your purposes the answers to both your questions are "no." For most audible frequencies, both of those surfaces should be considered reflective.


----------



## arcticbowman

HopefulFred said:


> Everything could be said to be absorptive, reflective, and diffusive at some frequencies and to some extent; however, for your purposes the answers to both your questions are "no." For most audible frequencies, both of those surfaces should be considered reflective.


That's what I had figured, especially with the rock, but I was holding out some hope on the foam. I'm not sure yet how much ceiling treatment I want to do, so I plan to hit the walls first and take a listen to see if I need to continue with the treatments. Thanks for your input.


----------



## drunkpenguin

So I put some absorption on the ceiling and I must say it made some improvements! (I think), I don't know for sure because at the same time I added a couple more to the side walls, but wow the subwoofer is really rockin now!

Question, 2 of the 4'x2' panels I installed are on the wall just under the ceiling. Does this work like a make shift base trap between the side wall and the ceiling? It sure acts like it does because the sub has never sounded better.


----------



## ereed

thecloneranger said:


> the art work is canvas shouldnt that be good acoustics or would it be better to have real acoustic panels?


Real acoustic panels is better since it has acoustic material built in that absorbs frequencies and turns it into heat. If you want the same artwork on acoustic panels you can send pics to them and they will print artwork on fabric for you if you choose that route.


----------



## ereed

drunkpenguin said:


> So I put some absorption on the ceiling and I must say it made some improvements! (I think), I don't know for sure because at the same time I added a couple more to the side walls, but wow the subwoofer is really rockin now!
> 
> Question, 2 of the 4'x2' panels I installed are on the wall just under the ceiling. Does this work like a make shift base trap between the side wall and the ceiling? It sure acts like it does because the sub has never sounded better.


Ceilings are one of the areas to treat to remove first reflection points so maybe it just sounds clearer and less muddy? 

Not sure what you mean by having panels right under the ceiling on side wall, it should be ear level where you sit. If you are sitting at your MLP and did the mirror trick, the panel should cover that point and that includes side wall, ceiling, floor, etc.

If you want something that acts like bass trap, they need to be really thick and place in corners. There are also some people that use bass trap that look like panels that place between the ceiling and walls as well. But usually the corners are where you want to absorb bass frequency since it is where it tends to build up the most. 

Maybe take some pics so we can see exactly what you are referring to.


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## johnnymacIII

*GIK 244 on Ceiling*

I am looking to hang some 244 bass traps on the ceiling, however I would like them to be flush. Has anyone had any experience hanging them flush and if so, what did you do?


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## ereed

johnnymacIII said:


> I am looking to hang some 244 bass traps on the ceiling, however I would like them to be flush. Has anyone had any experience hanging them flush and if so, what did you do?


I believe GIK can send you cloud brackets or you can make your own. I don't think they are made to be completely flush unless you find a way to mount it without seeing hardware. If you don't mind seeing some hardware you can get flat brackets and mount it on panel and ceiling. Here is an example.
https://www.google.com/search?q=fla...=p2WvWJqrMofRjAPTwIiABA#imgrc=eNul07BcYvgOrM:


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## darrellh44

johnnymacIII said:


> I am looking to hang some 244 bass traps on the ceiling, however I would like them to be flush. Has anyone had any experience hanging them flush and if so, what did you do?


When you say flush, I assume you mean no space between the panel and ceiling. I used these z-bar clips on my 2'x4'x2" GIK panels and they worked great. Use one set of 4 per panel.


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## drunkpenguin

ereed said:


> Maybe take some pics so we can see exactly what you are referring to.



Long story short: I have base traps in the corners already. A few years ago I added 4x2 panels above my surrounds in the back of the theater because I needed an easy way to hide the speaker cables. When I did that the sub unexpectedly really came to life in the center of the front row where I normally sit. 

Fast forward to now and I decided to put 2 more of these panels at my reflection point on the ceiling, while I was at it I put a couple more on the side walls in the front half of the theater purely for looks. Funny thing happened, the sub sounds even better at the listening position. I don't use rew, but multiple frequencies have improved big time, from the lower rumbles to the upper punch hitting base.

I also added some of those foam panels a bit lower for looks since they have little to no acoustic properties I'm told.

Anyways, it sounds really awesome and I appear to be breaking the normal rules here, but it's working. So I wonder if the upper panels are acting like mini base traps even though they don't straddle the corner like a traditional trap.


----------



## ereed

drunkpenguin said:


> Long story short: I have base traps in the corners already. A few years ago I added 4x2 panels above my surrounds in the back of the theater because I needed an easy way to hide the speaker cables. When I did that the sub unexpectedly really came to life in the center of the front row where I normally sit.
> 
> Fast forward to now and I decided to put 2 more of these panels at my reflection point on the ceiling, while I was at it I put a couple more on the side walls in the front half of the theater purely for looks. Funny thing happened, the sub sounds even better at the listening position. I don't use rew, but multiple frequencies have improved big time, from the lower rumbles to the upper punch hitting base.
> 
> I also added some of those foam panels a bit lower for looks since they have little to no acoustic properties I'm told.
> 
> Anyways, it sounds really awesome and I appear to be breaking the normal rules here, but it's working. So I wonder if the upper panels are acting like mini base traps even though they don't straddle the corner like a traditional trap.


Nice theater! If it already sounds good then I wouldn't mess with it. I think your ceiling panels look great as it is....not sure if you want to go through the hassle to make it flush. Up to you, but I dig it like it is.

If if you want to replace foam down the road you can....you can go with diffuser/absorber combo in those places if you wish. Those will absorb more than foam would and also diffuse really high frequencies. So thats the only thing I would for sound improvement since you have a great looking theater as it is and I wouldn't change too much.


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## kyzer soze

thecloneranger said:


> hi i have a small game/ theatre room i would like to treat since ive been reading on the importance of properly treated room. and since i have quite a bit of money invested i wanna do this before upgrading anymore. any way ill include a pic of my room and maybe i can get some suggestions are where to start. i have a umik coming in this week so i can started on rew. but just wanna get some ideas from you guys. for example i want to treat the ceilng and the walls were speakers are at maybe some bass traps for the corners. any help would be appreciated thanks.


I love your game room. Where did you get the T2?


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## thecloneranger

kyzer soze said:


> I love your game room. Where did you get the T2?


thanks i bought it from sideshow collectibles a year ago.


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## 12B4A

darrellh44 said:


> When you say flush, I assume you mean no space between the panel and ceiling. I used these z-bar clips on my 2'x4'x2" GIK panels and they worked great. Use one set of 4 per panel.


+1 for the Z-brackets. Many places other than acoustimac have them so one might be able to find them at a local store.



drunkpenguin said:


> Anyways, it sounds really awesome and I appear to be breaking the normal rules here, but it's working. So I wonder if the upper panels are acting like mini base traps even though they don't straddle the corner like a traditional trap.


They are absorbing some bass and in a good position for velocity-based absorption (porous) vs. the corners where pressure-based absorption (membrane, helmholtz) is more recommended. Without before and after measurements, it's not definitive to say that is what happened. They could be cleaning up a perceptible amount of ringing even if it may not be dramatic in the frequency response.


----------



## johnnymacIII

darrellh44 said:


> When you say flush, I assume you mean no space between the panel and ceiling. I used these z-bar clips on my 2'x4'x2" GIK panels and they worked great. Use one set of 4 per panel.


Thanks for the recommendation. They look like the perfect solution!


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## darrellh44

johnnymacIII said:


> Thanks for the recommendation. They look like the perfect solution!


Glad I could help. I mounted my clips differently than shown in the image at the bottom of that link. I turned all of the clips 180deg on the vertical axis so the clips are hidden by the panels once they're installed.


----------



## Nick V

I asked a while ago in this thread about making some sort of DIY treatment to cover the TV in a hybrid 2 channel music / TV room.

This is my current system:










2 GIK 242 panels behind the KEF LS50's taking care of the first reflection points behind the front L/R speakers










2 GIK 242 Panels handling the first reflection points on the right wall off the front L/R speakers and 2 Tri Traps in the rear right corner










2 GIK Art Panels handling the first reflection points behind the MLP and a GIK Monster Bass Trap on an angle in the rear left corner behind the Mirage BPS 400 12" bipolar subwoofer










I currently don't have the left wall treated as the standard GIK panels don't fit in the positions that I need. I might need to order some custom sizes as there is a large window with a cellular shade and a corner where the room widens a bit and also a wall plug near one of the first reflection points and a small window with a cellular shade beside the speaker on the other first reflection point. I need to find a way to treat these areas, I think I'll pull out my trusty mirror and measure up the specific areas to have GIK build some custom sized 242 panels for me. 

The room isn't perfect as there's an approximately 3-4 foot wide opening to the hallway beside the front right speaker. I will say though, that I've got this system sounding pretty great!!










(Bad cut/paste job) Would there be any significant sonic improvement from something like this covering the TV for dedicated music listening?


----------



## ereed

Nick V said:


> I asked a while ago in this thread about making some sort of DIY treatment to cover the TV in a hybrid 2 channel music / TV room.
> 
> This is my current system:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 2 GIK 242 panels behind the KEF LS50's taking care of the first reflection points behind the front L/R speakers
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 2 GIK 242 Panels handling the first reflection points on the right wall off the front L/R speakers and 2 Tri Traps in the rear right corner
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 2 GIK Art Panels handling the first reflection points behind the MLP and a GIK Monster Bass Trap on an angle in the rear left corner behind the Mirage BPS 400 12" bipolar subwoofer
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I currently don't have the left wall treated as the standard GIK panels don't fit in the positions that I need. I might need to order some custom sizes as there is a large window with a cellular shade and a corner where the room widens a bit and also a wall plug near one of the first reflection points and a small window with a cellular shade beside the speaker on the other first reflection point. I need to find a way to treat these areas, I think I'll pull out my trusty mirror and measure up the specific areas to have GIK build some custom sized 242 panels for me.
> 
> The room isn't perfect as there's an approximately 3-4 foot wide opening to the hallway beside the front right speaker. I will say though, that I've got this system sounding pretty great!!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> (Bad cut/paste job) Would there be any significant sonic improvement from something like this covering the TV for dedicated music listening?


For the windows you can get some thick heavy curtains that will help. Or you can get those standing feet that goes with GIK panels that you can move around when not in use. Such as having it standing at the windows and then move them out of the way when not in use.


----------



## Livin

Guys,
Planning to make 2'x4' OC703 absorption panels. 

Any benefit to making 2" thick panels with 1 or 2" gap between OC703 and wall?

I will not 'float' the panels, I prefer the look of fluh to the wall so the wood frame will flush to the wall while the OC703 will float... thus, ill have 3" or 4" deep wood side panel which will mount/contact the wall and the 2" thick OC703 is only in the front of the panel, leaving a 1 or 2 in air gap

thought?

thx


----------



## jjcook

Livin said:


> Guys,
> Planning to make 2'x4' OC703 absorption panels.
> 
> Any benefit to making 2" thick panels with 1 or 2" gap between OC703 and wall?
> 
> I will not 'float' the panels, I prefer the look of fluh to the wall so the wood frame will flush to the wall while the OC703 will float... thus, ill have 3" or 4" deep wood side panel which will mount/contact the wall and the 2" thick OC703 is only in the front of the panel, leaving a 1 or 2 in air gap
> 
> thought?
> 
> thx


Is this side wall, ceiling, or rear wall absorption? Assuming side or ceiling with 45 degree angle of incidence, you'll get about 2x better absorption below 150Hz with a 2" air gap:

http://www.acousticmodelling.com/ml..." air gap&s31=2&d31=50&v31=27000&s32=1&d32=50


----------



## erwinfrombelgium

Correct, but 2x of very little is still not a lot. I mean, 150 Hz will not be absorbed much by 2" of material. It's really mid+high absorption.

This said, it's obvious that the most effective use of 2" panels is indeed with a 2" gap.


----------



## JWL.GIK

Agreed. Adding an airgap roughly the same thickness as the panel itself will generally get you about another octave of useful absorption on the low end.


----------



## arcticbowman

Looking for input on my final plans to install absorption panels on my screen wall. I will be framing in the turret horizontally with 2X4's laid flat so I can have 2" OC703 boards placed flush with the face leaving a 1&1/2" gap between the panels and the insulated concrete foam wall. The sides are 35&1/2" wide each and the center is 73" wide, so it works out perfect for 3, 48" panels to cover the 144" width. The height works out well too, with laying the 2X4's flat, I will frame in three rows of OC703 boards for a total height of 78". This puts me from the top of the stage to flush with the ceiling. I plan to install 2X2's on the top and bottom edges of the 2X4's and flush with the back wall to help frame in the OC703 boards.

I'm wondering about fabric to cover the entire span. I'd like to use the JoAnn black polyester fabric since it is 75" wide. With that width, I can hide the seams in the corners vertically. If using GOM FR701 is more advantageous, I will go with that and run a single seam horizontally. Is velvet a possibility, or is the GOM the best stuff out there? I'm looking for guidance on which fabric would serve me best. I do want a clean look as I will have behind the screen lighting, but it doesn't have to be perfect.

For the outside corners (on the black wall), I plan to stack OC703 triangles that will be 2-6" thick. Should I run these bass traps the whole 78" of height, or can I keep them around 4-5' tall? I will be installing stationary curtains in the corners that will be mainly for show, but how will those effect the bass traps as they will be completely covering them? I was considering using velvet for the curtains as they will be visible in the room.

Thanks in advance.


----------



## dchalfont

I don't know if this is the sort of question to ask here, but the walls in my home theatre room vibrate loudly in certain places and I want to put about 3 screws through the wall and into the frame because when I press my hand against the vibrating places the noise stops immediately, so fixing them will obviously do the trick.

But the studs in walls are only going to be present in the places where the wall is already screwed to the frame isn't it?

Or should I be getting someone to see if the existing screws that were put through into the frame were not screwed in securely enough?

It is a brand new house. Less that 5 months since completion.

I have had a lot of problems and am taking the builder through the process to get him to fix issues with the house but I didn't raise the issue of the vibration with them because I doubt walls vibrating from $25000 equipment in a 16x16x8 room falls under expectations of construction.

But I don't want to just do whatever works, I want to do it right so that it is fixed permanenty and in a way that doesn't mess up the walls. Pulling sections of the wall out etc is also absolutely noy an option.

Basically I'm hoping I can get about 30-40 of the right type of screws put through the wall, into the frame and then filled on the ends, sanded and painted. Also a half dozen on the other side of the wall.

Is that the right track or is this a much bigger issue?


----------



## Lesmor

dchalfont said:


> I don't know if this is the sort of question to ask here, but the walls in my home theatre room vibrate loudly in certain places and I want to put about 3 screws through the wall and into the frame because when I press my hand against the vibrating places the noise stops immediately, so fixing them will obviously do the trick.
> 
> But the studs in walls are only going to be present in the places where the wall is already screwed to the frame isn't it?
> 
> Or should I be getting someone to see if the existing screws that were put through into the frame were not screwed in securely enough?
> 
> It is a brand new house. Less that 5 months since completion.
> 
> I have had a lot of problems and am taking the builder through the process to get him to fix issues with the house but I didn't raise the issue of the vibration with them because I doubt walls vibrating from $25000 equipment in a 16x16x8 room falls under expectations of construction.
> 
> But I don't want to just do whatever works, I want to do it right so that it is fixed permanenty and in a way that doesn't mess up the walls. Pulling sections of the wall out etc is also absolutely noy an option.
> 
> Basically I'm hoping I can get about 30-40 of the right type of screws put through the wall, into the frame and then filled on the ends, sanded and painted. Also a half dozen on the other side of the wall.
> 
> Is that the right track or is this a much bigger issue?


The 16x16x8 room dimensions might be the issue with the room modes being stimulated


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## dchalfont

Lesmor said:


> The 16x16x8 room dimensions might be the issue with the room modes being stimulated


There are obviously room mpdes but that's an entirely differnt issue from vibrating walls where they are not fixed properly to the frame. Especially when the vibrations are nowhere near the corners.

I called a builder who does small jobs and asked about it, mentioning my builder and he said that he doesn't know how my builder still has a license and that he recently worked on another house built by the same a-hole who screwed up mine....and that that house had the exact same issue. Them I called the plasterer recommended by the guy I called and when I mentioned my builders name he said the same thing. He checked the house out and said that not only did he likely not use glue like he was supposed to. But that it seemed like he only used nails to fix the wall to the frame in order to cut corners and explained that a bowing in a skirting board is proof that he hasn't fixed the wall panels to the frames properly.

So it's a construction issue.

Anyway problem solution found now...


----------



## Lesmor

dchalfont said:


> There are obviously room mpdes but that's an entirely differnt issue from vibrating walls where they are not fixed properly to the frame. Especially when the vibrations are nowhere near the corners.
> 
> I called a builder who does small jobs and asked about it, mentioning my builder and he said that he doesn't know how my builder still has a license and that he recently worked on another house built by the same a-hole who screwed up mine....and that that house had the exact same issue. Them I called the plasterer recommended by the guy I called and when I mentioned my builders name he said the same thing. He checked the house out and said that not only did he likely not use glue like he was supposed to. But that it seemed like he only used nails to fix the wall to the frame in order to cut corners and explained that a bowing in a skirting board is proof that he hasn't fixed the wall panels to the frames properly.
> 
> So it's a construction issue.
> 
> Anyway problem solution found now...


That's good but if you post a question in a acoustic treatment thread don't get narked if you then get a suggestion of room modes vibrating the loose panels reply and then say of course there are room modes.
If you know that much then you also know to use another room as the one you are using is unsuitable.

I am not in the least bit interested in, as we say in the UK cowboy builders,we have enough of our own.


----------



## dnoonie

Be careful, you don't want a wall to fall on you. You should check local building code. Be careful where you use screws and nails.

Building code in my area states nails must be used when building wood homes and not screws. I looked it up and the reason behind it is that screws sheer and nails bend. So in an earthquake the house built with wood and nails would be ruined but it would still hold together because and not collapse flat because the nails would bend and not break. Try a search, there are some great videos of tests out there, it's pretty interesting. In an earthquake you'd be able to crawl out of a wood house put together with nails, where a wood house built with screws would likely kill you.

Of course attaching Sheetrock is another story.

Cheers,


----------



## JMAX2016

Hi Guys! So I could use some help here. I need some help on what to do with acoustic treatments. I have a 100’ roll of 1” Linacoustic, and 8 - 2’x4’x2” panels. Where should I put them? I have an AT screen, and my theater room is 12’ wide by 20’ long. I know I want to hit the first reflection points, but my question is more of, if you had that for acoustic treatment, what would you do? Side note, I love big bass in movies, so I don’t want to reduce the bass in the room at all. Thank you.


----------



## JMAX2016

Just to give you guys an idea of my space. All of the fabric in the room now is acoustically transparent fabric. So I'm planning on putting the treatment behind the fabric. This is also my old screen. I now have an AT screen. the ceilings are about 8 ft high.


----------



## Livin

erwinfrombelgium said:


> Correct, but 2x of very little is still not a lot. I mean, 150 Hz will not be absorbed much by 2" of material. It's really mid+high absorption.
> 
> This said, it's obvious that the most effective use of 2" panels is indeed with a 2" gap.





JWL.GIK said:


> Agreed. Adding an airgap roughly the same thickness as the panel itself will generally get you about another octave of useful absorption on the low end.


I ended up going with 1x4 wood.. which is really 3.5" deep. So, I'll have about a 1.5" air gap between the drywall and the OC703.

Question: Does drilling 1" holes in the wood frames really do much, like this guy did...


----------



## donktard

Hey guys, not sure if this question was asked here. What would be preferred room finish material for a small dedicated HT room to achieve best acoustical performance? Drywall, wood paneling, something else? Of course, plan is to put acoustic treatments on top of that.


----------



## Nick V

donktard said:


> Hey guys, not sure if this question was asked here. What would be preferred room finish material for a small dedicated HT room to achieve best acoustical performance? Drywall, wood paneling, something else? Of course, plan is to put acoustic treatments on top of that.


This stuff looks pretty good!! 
QuietRock 545


----------



## erwinfrombelgium

Drywall is most cost effective. It has the right "limp mass " properties. Best practice is double layer with GreenGlue in between. This absorbs down to 250 Hz. Sub 100 Hz is difficult to contain other than with concrete.


----------



## 12B4A

Livin said:


> Question: Does drilling 1" holes in the wood frames really do much, like this guy did...


It makes the frame lighter. 

If I mashed the buttons correctly, 1" would seem to help with absorbing ~7khz on up for all sound hitting the panel mostly tangentially?


----------



## donktard

erwinfrombelgium said:


> Drywall is most cost effective. It has the right "limp mass " properties. Best practice is double layer with GreenGlue in between. This absorbs down to 250 Hz. Sub 100 Hz is difficult to contain other than with concrete.


I was not asking specifically to contain sound, I have a pretty good idea what is required for that. I was wondering if any material is beneficial specifically for room acoustics, basically, to take the load off any additional acoustic treatment I might add. For example, bathroom tile or glass walls  sound like a bad idea.


----------



## JMAX2016

From what I have read, the best practice for behind the screen wall is 1" linacoustic, poly, then 1" linacoustic. Does it matter what mm the poly is? I think BIG has said 4mm and I've heard a couple say 6mm. And does this include the side wall that goes out until the screen as well(for me it's about 36")?


----------



## Mashie Saldana

JMAX2016 said:


> From what I have read, the best practice for behind the screen wall is 1" linacoustic, poly, then 1" linacoustic. Does it matter what mm the poly is? I think BIG has said 4mm and I've heard a couple say 6mm. And does this include the side wall that goes out until the screen as well(for me it's about 36")?


Don't confuse mm for mil (which is a thousand of a mm), the poly they are referring to is 0.004 to 0.006mm.


----------



## Livin

JMAX2016 said:


> From what I have read, the best practice for behind the screen wall is 1" linacoustic, poly, then 1" linacoustic. Does it matter what mm the poly is? I think BIG has said 4mm and I've heard a couple say 6mm. And does this include the side wall that goes out until the screen as well(for me it's about 36")?



Originally Posted by *BIGmouthinDC*  
_Per both Toole and Erskine. Fiberglass insulation in front corners for the purposes of bass trapping is waste of money. At the front corners standing waves are at their highest pressure level but lowest velocity. Fiberglass is a velocity bass absorber. You want to make a dent on bass you need membrane absorbers. Of course you should know what frequencies you need to tame because membrane traps are effective over certain frequencies. So what to do? Put a layer of 3mil plastic between the two layers of linacoustic on the front wall and it will behave as a membrane trap of sorts.

http://www.homedepot.com/p/Husky-100...083C/202184059_


----------



## JMAX2016

Mashie Saldana said:


> Don't confuse mm for mil (which is a thousand of a mm), the poly they are referring to is 0.004 to 0.006mm.


Okay, thank you. I actually thought it was mm.


----------



## JMAX2016

Livin said:


> Originally Posted by *BIGmouthinDC*
> _Per both Toole and Erskine. Fiberglass insulation in front corners for the purposes of bass trapping is waste of money. At the front corners standing waves are at their highest pressure level but lowest velocity. Fiberglass is a velocity bass absorber. You want to make a dent on bass you need membrane absorbers. Of course you should know what frequencies you need to tame because membrane traps are effective over certain frequencies. So what to do? Put a layer of 3mil plastic between the two layers of linacoustic on the front wall and it will behave as a membrane trap of sorts.
> 
> http://www.homedepot.com/p/Husky-100...083C/202184059_


Okay, thanks. I'm going to go get some 3 mil today and put it up.


----------



## JMAX2016

Guys, can someone give me some advice on what to do on the theater side of the AT screen. I've read hundreds of pages and listened to 2 podcasts on acoustics. The problem is that they seem to conflict with each other. What Anthony Gramani says makes sense. But then I see these $300,000 theaters, and they are doing something slightly different. Mainly the percentage he says to cover. I know I want atleast 2" panels. I have all rock wool panels as of now. And I'll have what is left of my Linacoustic roll I could use.


----------



## JMAX2016

I could even make more panels. I just want to do it the RIGHT way!


----------



## drunkpenguin

FWIW, I went from floor to ceiling panels to no panels on the front wall after reading accoustics on realtraps.com and I improved my sound big time. I have some foam panels directly behind the speakers to tame the voice echos, but I love the way my theater sounds now.


----------



## thedrmike

I would like some advice. My local building supply store has Supress Sound Deadening Board, and I'm wondering if I can use it as a substitute for Linacoustic/Insul-shield etc.

http://www.supressproducts.com/soundproofing-articles/Sound-Deadening-Board.html

Thanks!


----------



## Mashie Saldana

Livin said:


> Originally Posted by *BIGmouthinDC*
> _Per both Toole and Erskine. Fiberglass insulation in front corners for the purposes of bass trapping is waste of money. At the front corners standing waves are at their highest pressure level but lowest velocity. Fiberglass is a velocity bass absorber. You want to make a dent on bass you need membrane absorbers. Of course you should know what frequencies you need to tame because membrane traps are effective over certain frequencies. So what to do? Put a layer of 3mil plastic between the two layers of linacoustic on the front wall and it will behave as a membrane trap of sorts.
> 
> http://www.homedepot.com/p/Husky-100...083C/202184059_


Considering limp mass absorbers target a very narrow frequency range, which frequency can you hope to target with this sandwich?

Now looking at the DIY limp mass absorbers they build over at Gearslutz I can't imagine 3mil of plastic will do anything at all considering they use a thousand times thicker steel plates as membranes.


----------



## JMAX2016

drunkpenguin said:


> FWIW, I went from floor to ceiling panels to no panels on the front wall after reading accoustics on realtraps.com and I improved my sound big time. I have some foam panels directly behind the speakers to tame the voice echos, but I love the way my theater sounds now.


That's similar to what Anthony Gramani says. So that's what makes it confusing. I just finished installing the 1" lin, 3 mil, 1" lin. About to calibrate then start listening. If BIG says this is the way to go though, I believe him. He seems to be knowledgable as can be with this.


----------



## dnoonie

JMAX2016 said:


> That's similar to what Anthony Gramani says. So that's what makes it confusing. I just finished installing the 1" lin, 3 mil, 1" lin. About to calibrate then start listening. If BIG says this is the way to go though, I believe him. He seems to be knowledgable as can be with this.


Check this article,http://realtraps.com/art_front-wall.htm

And this thread, https://www.gearslutz.com/board/bas...oam-etc/556520-treatment-behind-monitors.html

Cheers,


----------



## harrisu

Hey guys,
Hope I can get some help here. I have a 23Lx14Wx8H room. Been reading on acoustic treatment. As of now, I have 703 2" and 703 4" panels in the room. Room is specifically used for Home Theater and has a 7.2.4 system. I recently watched Anthony Grimani HT Geek video 



 which made me realize that my room is way off from what he was discussing. 

In short, he has a 20% absorption and 25% diffusion rule. He also mentinoed that the front wall shouldn't be completely covered. Well, in my case, all I have is absorption and absorption and absorption. I have the whole front wall covered with linacoustic and all room corners have 8" 703. Then back wall is also mostly treated with absorption of 2" 703". Side wall I left the first reflection and covered 2nd reflection. Also ceiling has 4 panels of 4" 703 around 1st and 2nd reflection. 

This all absorption is now making me think that the room might be absorbing way more than it needs to. I do use REW and very familiar with its usage. Now the questions

1 - Do you guys agree that a dedicated HT room with 11 channels should be 20% absorption and 25% diffusion?
2 - If yes then how much of a distance is required to use diffusion? Armani recommended to use 3D diffuser on back of MLP and 2D on Front are of MLP. My MLP is 5 feet away from back wall. Can I still use 3D diffuser. As for front, my projector screen is 10' away from MLP. Attaching the image he used in presentation. Image shows a good distance from back wall but not so much from side. So I'm guessing that 3D diffuser doesn't have to be too far.
3 - Front wall: should it not be covered with linacoustic to make it all dead?

I'm hoping that someone will jump on this post cause all this info and stuff is driving me crazy. I purchase good speakers (JBL 4722n) but now feeling that I'm not utilizing their power.


----------



## sdurani

harrisu said:


> In short, he has a 20% absorption and 25% diffusion rule.


That's his approach, based on his preference.


> Do you guys agree that a dedicated HT room with 11 channels should be 20% absorption and 25% diffusion?


Only if you like the resulting sound.


----------



## sludgeogre

harrisu said:


> 1 - Do you guys agree that a dedicated HT room with 11 channels should be 20% absorption and 25% diffusion?
> 2 - If yes then how much of a distance is required to use diffusion? Armani recommended to use 3D diffuser on back of MLP and 2D on Front are of MLP. My MLP is 5 feet away from back wall. Can I still use 3D diffuser. As for front, my projector screen is 10' away from MLP. Attaching the image he used in presentation. Image shows a good distance from back wall but not so much from side. So I'm guessing that 3D diffuser doesn't have to be too far.
> 3 - Front wall: should it not be covered with linacoustic to make it all dead?


1. 25% diffusion is waaaay too much to me, and 20% absorption is too low. From everything I've read lately and the small amount of testing I'm able to do, 40% absorption is a better rule of thumb. Diffusion is very hard to say, because the results you get vary drastically depending on the room and the MLP position. If you have 6 feet between the MLP and the diffusor, then I think you can go as high as 20% diffusion if you really want to, but if you don't have that much room to work with, you want to go with all absorption, but leave a little reflection in the room to keep the soundstage large. Diffusion in small rooms just smears everything together since the diffusor doesn't have enough space to diffuse sound into.

2. Like I said, 6 feet is bare minimum. A guy at metal-fi is playing with geofusors now and is having a weird time with them, he's finding that they work well below ear level in his room but he's still playing with them. https://www.metal-fi.com/forum/viewtopic.php?f=14&t=633&start=70

3. Don't cover the entire front wall. A lot of guys do it and say it sounds great but end up tearing most of it out after a while. A guy just did this in this thread a few pages back I think and reported that his sound opened back up substantially. It's fine to treat directly behind the speakers and in the corners behind the speakers, but any more than that is really unnecessary and costly. If you hunt around real traps you can find some articles by Ethan Winer that talk about this exact concept.


----------



## harrisu

sdurani said:


> That's his approach, based on his preference. Only if you like the resulting sound.


Yeah but this means that I have to buy all these and then install and then try and if I don't like it, I'm left with a lot of stuff. I'm sure there are some rules/theories that majority agrees upon to start with? Like, may be a way to use REW to know how dead my room is???? I don't know how to interpret RT60 but I think it is supposed to show how alive room is. Don't know if its applicable to room of my size because someone mentioned that the graph is useful only for large rooms.



sludgeogre said:


> 1. 25% diffusion is waaaay too much to me, and 20% absorption is too low. From everything I've read lately and the small amount of testing I'm able to do, 40% absorption is a better rule of thumb. Diffusion is very hard to say, because the results you get vary drastically depending on the room and the MLP position. If you have 6 feet between the MLP and the diffusor, then I think you can go as high as 20% diffusion if you really want to, but if you don't have that much room to work with, you want to go with all absorption, but leave a little reflection in the room to keep the soundstage large. Diffusion in small rooms just smears everything together since the diffusor doesn't have enough space to diffuse sound into.
> 
> 2. Like I said, 6 feet is bare minimum. A guy at metal-fi is playing with geofusors now and is having a weird time with them, he's finding that they work well below ear level in his room but he's still playing with them. https://www.metal-fi.com/forum/viewtopic.php?f=14&t=633&start=70
> 
> 3. Don't cover the entire front wall. A lot of guys do it and say it sounds great but end up tearing most of it out after a while. A guy just did this in this thread a few pages back I think and reported that his sound opened back up substantially. It's fine to treat directly behind the speakers and in the corners behind the speakers, but any more than that is really unnecessary and costly. If you hunt around real traps you can find some articles by Ethan Winer that talk about this exact concept.


Yeah I wouldn't want the smear the sound. Before I made all the changes, I removed everything from room and when I played some music, it did sound better when I didn't have anything (no absorbtion) on back wall corners. If I put the absorption panel there, it does feel like it was absorbing more than I needed to. 
I think first, I'll remove the Linacoustic from front wall cause its just absorbing everything and then try out. 
One of my concern is that I feel like I don't have absorption in balance. Front wall is completely dead, back wall is 100% starting from ear level and going 4 feet up, side wall has one one panel on each side on 2nd reflection and I have 4 panels on top. The reason I didn't install more panels on side wall is because many owners of my speaker (JBL 4722n) said that it sounds great when first reflection is not absorbed. So I left that open by just having one panel on 2nd reflection. But you can see that my room is unbalanced where at one place too much absorption and one place almost nothing.


----------



## JMAX2016

harrisu said:


> Yeah but this means that I have to buy all these and then install and then try and if I don't like it, I'm left with a lot of stuff. I'm sure there are some rules/theories that majority agrees upon to start with? Like, may be a way to use REW to know how dead my room is???? I don't know how to interpret RT60 but I think it is supposed to show how alive room is. Don't know if its applicable to room of my size because someone mentioned that the graph is useful only for large rooms.
> 
> 
> 
> Yeah I wouldn't want the smear the sound. Before I made all the changes, I removed everything from room and when I played some music, it did sound better when I didn't have anything (no absorbtion) on back wall corners. If I put the absorption panel there, it does feel like it was absorbing more than I needed to.
> I think first, I'll remove the Linacoustic from front wall cause its just absorbing everything and then try out.
> One of my concern is that I feel like I don't have absorption in balance. Front wall is completely dead, back wall is 100% starting from ear level and going 4 feet up, side wall has one one panel on each side on 2nd reflection and I have 4 panels on top. The reason I didn't install more panels on side wall is because many owners of my speaker (JBL 4722n) said that it sounds great when first reflection is not absorbed. So I left that open by just having one panel on 2nd reflection. But you can see that my room is unbalanced where at one place too much absorption and one place almost nothing.


Harrisu,
So I've really been playing around with acoustic treatment over the past two months, moving them, stacking them (for lower freq absorption), and a loooot of listening. I have a 7.2.4 setup, with a 120" AT screen. Here's what I've learned, and maybe this will help in some kind of way.

1. Only absorb the whole front wall if you have an AT screen. Otherwise, I don't like the sound. I use 1" lin, plastic membrane, 1" lin (Thanks BIG!). I love the sound of this, because less SBIR (speaker boundary effect), great speaker localization, and great bass trapping.

2. Make sure both side walls have equal amount of absorption, and at the same height and distance. In other words, symmetrical. Otherwise, I can hear the difference. My side walls are covered about 40%.

3. I like the back wall about 50% covered with absorption. I hear this difference in the dialogue.

4. I use 3" rock wool at first reflection points, and 2" almost everywhere else.

5. Ceiling clouds, I have not tried, but I want to try the at the first reflection point on ceiling.

6. With the amount of absorption I just mentioned, the amount of power you need to reach the same SPL is greater. Meaning that if you'd regularly play movies at 60% of the receiver/amp capability, you'll need to run it at 75%. But that sound will be way more clean and linear.

7. I have not used REW yet. I have the app, but no mic. I would love to measure my room. Decay times, etc. But to my ears, this is the best my room has sounded.

What do you guys think?


----------



## Mashie Saldana

JMAX2016 said:


> Harrisu,
> So I've really been playing around with acoustic treatment over the past two months, moving them, stacking them (for lower freq absorption), and a loooot of listening. I have a 7.2.4 setup, with a 120" AT screen. Here's what I've learned, and maybe this will help in some kind of way.
> 
> 1. Only absorb the whole front wall if you have an AT screen. Otherwise, I don't like the sound. I use 1" lin, plastic membrane, 1" lin (Thanks BIG!). I love the sound of this, because less SBIR (speaker boundary effect), great speaker localization, and great bass trapping.
> 
> 2. Make sure both side walls have equal amount of absorption, and at the same height and distance. In other words, symmetrical. Otherwise, I can hear the difference. My side walls are covered about 40%.
> 
> 3. I like the back wall about 50% covered with absorption. I hear this difference in the dialogue.
> 
> 4. I use 3" rock wool at first reflection points, and 2" almost everywhere else.
> 
> 5. Ceiling clouds, I have not tried, but I want to try the at the first reflection point on ceiling.
> 
> 6. With the amount of absorption I just mentioned, the amount of power you need to reach the same SPL is greater. Meaning that if you'd regularly play movies at 60% of the receiver/amp capability, you'll need to run it at 75%. But that sound will be way more clean and linear.
> 
> 7. I have not used REW yet. I have the app, but no mic. I would love to measure my room. Decay times, etc. But to my ears, this is the best my room has sounded.
> 
> What do you guys think?


What size is your room?


----------



## JMAX2016

Mashie Saldana said:


> What size is your room?


My room is 20x12x8.


----------



## harrisu

JMAX2016 said:


> Harrisu,
> So I've really been playing around with acoustic treatment over the past two months, moving them, stacking them (for lower freq absorption), and a loooot of listening. I have a 7.2.4 setup, with a 120" AT screen. Here's what I've learned, and maybe this will help in some kind of way.
> 
> 1. Only absorb the whole front wall if you have an AT screen. Otherwise, I don't like the sound. I use 1" lin, plastic membrane, 1" lin (Thanks BIG!). I love the sound of this, because less SBIR (speaker boundary effect), great speaker localization, and great bass trapping.
> 
> 2. Make sure both side walls have equal amount of absorption, and at the same height and distance. In other words, symmetrical. Otherwise, I can hear the difference. My side walls are covered about 40%.
> 
> 3. I like the back wall about 50% covered with absorption. I hear this difference in the dialogue.
> 
> 4. I use 3" rock wool at first reflection points, and 2" almost everywhere else.
> 
> 5. Ceiling clouds, I have not tried, but I want to try the at the first reflection point on ceiling.
> 
> 6. With the amount of absorption I just mentioned, the amount of power you need to reach the same SPL is greater. Meaning that if you'd regularly play movies at 60% of the receiver/amp capability, you'll need to run it at 75%. But that sound will be way more clean and linear.
> 
> 7. I have not used REW yet. I have the app, but no mic. I would love to measure my room. Decay times, etc. But to my ears, this is the best my room has sounded.
> 
> What do you guys think?


Thanks for sharing. My turn now 
1 - Managing base decay: I have had all this done that you are doing before. I have had Lin but I just went with 1". I don't think it really matters if you have 1" then plastic and then 1". Using just 1" will absorb High frequencies just fine. I don't think making it 2" with plastic will help will Low/Mid frequencies. I use REW. In fact, I used it by placing each panel and then took reading to see what it does and then added more or removed based on what I saw. So, if you want to make sure the room decays withing 300ms, you take reading and start observing. When I took all the panels out, the dacay was going beyond 450ms. Then I added 8" 703 on front wall corneres and also in one back wall corner. Then took reading and then installed the ceiling panels (3 4" 703) and 1 4" 703 on each side side wall on 2nd reflection. Took reading and all the mid-bass (150 onward) was well within 300ms. Now if you have anything under 150 going beyond 300-400ms, you'd have to add a lot more to tame them down. In my case, I didn't. For some reason, my room does resonate at 60Hz but I think its my mic (will post question on REW thread). Other than that, my whole waterfall graph (that shows decay) is within 300 ms. So that takes care of bass.

2 : Room Reflection. So after installing bass traps (or Mid-bass traps I should call), I moved my target to room reflection. At this point, I already have 1" lin on front wall and 50% back wall covered with 2" 703 and corner bass traps and panels on top and side wall. Checked the Impulse response. From top of my head, it should be below -20. When I checked, I hardly had any spike going above -20. Now, there has been discussion where some say to have Lin on front wall and some say that you are damping the room too much if your front wall is completely covered. So, it was time to find out. I took the whole 1" Lin off. Then put 1 2" 703 behind C starting from its tweeter height going up. Then took reading and guess what !!! I didn't see any noticeable change in reflection. So Lin really wasn't taming that much for me for early reflection and I think it was damping my room. 

Now all that is purely based on what REW is showing me. Listening is obviously the final answer to all the changes which I'll be doing over the weekend. As of now, I have 3 corners covered with 8" 703 with front ones from top to bottom and back only up to ear level (since I don't want it to absorb L/R reflection). Then I have only 1 2" 703 panel on each side wall parallel to each other and 3 4" panels on ceiling (1 for L, 1 for R and 1 for C). Then I have 1 4" 703 behind C on front wall starting from tweeter to all the way up. All this has gotten the low frequency under control within 300ms and also the reflection. 

BTW, I do have AT screen but its not weave. Its a Perf screen with 1.3 gain (amazing . With screen on, I do loose 8db on high frequency which Dirac (room correction system) fixes for me. I guess the point I'm driving to is that Lin on front wall might not be necessary and its definitely not for helping out with mid bass. With a setup above 5.1, we do have speakers firing towards the front wall and it might help absorb them. But I don't want to just put it there and go with it. Instead, I want to first listen to my room and if I find that its too reflective, only then I'll add more absorption. This will ensure that I'm not over absorbing. My speakers are 106dB sensitive so I can easily over damp my room and crank up the volume and they won't give up on me.


----------



## JMAX2016

harrisu said:


> Thanks for sharing. My turn now
> 1 - Managing base decay: I have had all this done that you are doing before. I have had Lin but I just went with 1". I don't think it really matters if you have 1" then plastic and then 1". Using just 1" will absorb High frequencies just fine. I don't think making it 2" with plastic will help will Low/Mid frequencies. I use REW. In fact, I used it by placing each panel and then took reading to see what it does and then added more or removed based on what I saw. So, if you want to make sure the room decays withing 300ms, you take reading and start observing. When I took all the panels out, the dacay was going beyond 450ms. Then I added 8" 703 on front wall corneres and also in one back wall corner. Then took reading and then installed the ceiling panels (3 4" 703) and 1 4" 703 on each side side wall on 2nd reflection. Took reading and all the mid-bass (150 onward) was well within 300ms. Now if you have anything under 150 going beyond 300-400ms, you'd have to add a lot more to tame them down. In my case, I didn't. For some reason, my room does resonate at 60Hz but I think its my mic (will post question on REW thread). Other than that, my whole waterfall graph (that shows decay) is within 300 ms. So that takes care of bass.
> 
> 2 : Room Reflection. So after installing bass traps (or Mid-bass traps I should call), I moved my target to room reflection. At this point, I already have 1" lin on front wall and 50% back wall covered with 2" 703 and corner bass traps and panels on top and side wall. Checked the Impulse response. From top of my head, it should be below -20. When I checked, I hardly had any spike going above -20. Now, there has been discussion where some say to have Lin on front wall and some say that you are damping the room too much if your front wall is completely covered. So, it was time to find out. I took the whole 1" Lin off. Then put 1 2" 703 behind C starting from its tweeter height going up. Then took reading and guess what !!! I didn't see any noticeable change in reflection. So Lin really wasn't taming that much for me for early reflection and I think it was damping my room.
> 
> Now all that is purely based on what REW is showing me. Listening is obviously the final answer to all the changes which I'll be doing over the weekend. As of now, I have 3 corners covered with 8" 703 with front ones from top to bottom and back only up to ear level (since I don't want it to absorb L/R reflection). Then I have only 1 2" 703 panel on each side wall parallel to each other and 3 4" panels on ceiling (1 for L, 1 for R and 1 for C). Then I have 1 4" 703 behind C on front wall starting from tweeter to all the way up. All this has gotten the low frequency under control within 300ms and also the reflection.
> 
> BTW, I do have AT screen but its not weave. Its a Perf screen with 1.3 gain (amazing . With screen on, I do loose 8db on high frequency which Dirac (room correction system) fixes for me. I guess the point I'm driving to is that Lin on front wall might not be necessary and its definitely not for helping out with mid bass. With a setup above 5.1, we do have speakers firing towards the front wall and it might help absorb them. But I don't want to just put it there and go with it. Instead, I want to first listen to my room and if I find that its too reflective, only then I'll add more absorption. This will ensure that I'm not over absorbing. My speakers are 106dB sensitive so I can easily over damp my room and crank up the volume and they won't give up on me.


Interesting... Especially the part where you said it measured the same taking the Lin out... Let us know how the listening goes! 
What are you using for a mic for REW? And don't you need a sound board to hook the mic and on the other end your computer into?


----------



## Livin

I just inherited 10 panels of Armstrong Ceilings Shasta White Textured 15/16-in Drop Acoustic Panel Ceiling Tiles (Common: 48-in x 24-in)

... ideas on useful or interesting things to do with them?

I have 2" OC703 I'm starting to make wall (maybe ceiling) panels with. Currently two 2" panels (2.5" frames) hang on side-wall first reflection (just in front of the row of seating) - on diagram, black with red border

I'm also thinking I'll put in a ceiling cloud : on diagram, has yellow border

Most of the ceiling is 9' and all speakers are hug at about 7.5' ... Atmos ceiling speakers (A) are at 9'
There is very little space behind the main speakers behind the AT screen - thought maybe using the Armstrong panels there - will they make a difference being only 1" thick?

interested in your thoughts on where treatments should go and what to do with the 1" Armstrong panels.


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## Mashie Saldana

JMAX2016 said:


> What are you using for a mic for REW? And don't you need a sound board to hook the mic and on the other end your computer into?


Most people use the MiniDSP UMIK-1 microphone that only requires a spare USB port on the computer. They are calibrated at factory so fairly accurate once you load in the calibration file in REW.


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## healthnut

Hi: I'd like to get some feedback concerning corner traps. I recently soundproofed my entire room. This involved tearing out the drop ceiling and installing double drywall, GG, safnsound, isolation clips and hat channel. However, this increased my ceiling height, so the ceiling is now about a foot taller than previously. My existing GIK corner bass traps are now too short to cover the increase in height. Is it worth investing in 4 one foot corner traps to correct this, or is it not worth addressing in your opinion? 


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## PretzelFisch

healthnut said:


> Hi: I'd like to get some feedback concerning corner traps. I recently soundproofed my entire room. This involved tearing out the drop ceiling and installing double drywall, GG, safnsound, isolation clips and hat channel. However, this increased my ceiling height, so the ceiling is now about a foot taller than previously. My existing GIK corner bass traps are now too short to cover the increase in height. Is it worth investing in 4 one foot corner traps to correct this, or is it not worth addressing in your opinion?
> 
> 
> Sent from my iPhone using Tapatalk


they do the most good where all three corners meet. you could have a gap in the middle between the two you have stacked.


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## healthnut

PretzelFisch said:


> they do the most good where all three corners meet. you could have a gap in the middle between the two you have stacked.




Thanks, but I don't think I understand the second part of your comment. Do you mean if I added a small one, there would be a gap between them and it would be better to order new ones at the correct height?


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## Mashie Saldana

healthnut said:


> Thanks, but I don't think I understand the second part of your comment. Do you mean if I added a small one, there would be a gap between them and it would be better to order new ones at the correct height?
> 
> 
> Sent from my iPhone using Tapatalk


We assume that you currently have two corner traps stacked on top of each other, if you lift the top one so it is against the ceiling you will get the most benefit without adding more traps.


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## healthnut

Mashie Saldana said:


> We assume that you currently have two corner traps stacked on top of each other, if you lift the top one so it is against the ceiling you will get the most benefit without adding more traps.




Thanks for the reply. I have one trap on each corner, but they're all too short to reach the ceiling, by about a foot. Looks like I need to add smaller ones to reach into the ceiling. 


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## Mashie Saldana

healthnut said:


> Thanks for the reply. I have one trap on each corner, but they're all too short to reach the ceiling, by about a foot. Looks like I need to add smaller ones to reach into the ceiling.
> 
> 
> Sent from my iPhone using Tapatalk


Cool, I didn't know the GIK corner traps were available in 8ft tall units, I thought they were around 4ft each.


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## ereed

Mashie Saldana said:


> Cool, I didn't know the GIK corner traps were available in 8ft tall units, I thought they were around 4ft each.


GIK bass traps are stackable and support 50 lbs weight. Didn't know they had 8 foot version, always known them to have 4 feet pieces. Many bass traps to choose from including the alpha series if you want traps with some diffusion. I don't have corner traps, just the 244 bass traps behind my rear wall and they do improve decay times in my room.


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## PretzelFisch

I have 2 4 footers bass traps stacked in each rear corner. Front wall I have a 4 foot and custom sized bass trap sitting on my sub. They did a great job helping to even out the bass and lower the decay time.


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## JMAX2016

Mashie Saldana said:


> Most people use the MiniDSP UMIK-1 microphone that only requires a spare USB port on the computer. They are calibrated at factory so fairly accurate once you load in the calibration file in REW.


Thanks Mashie. I'm going to look into getting one! Looks like Parts Express has it for $85. Their website has it for $75. I'm not sure if that includes shipping too or not.


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## Livin

Livin said:


> I just inherited 10 panels of Armstrong Ceilings Shasta White Textured 15/16-in Drop Acoustic Panel Ceiling Tiles (Common: 48-in x 24-in)
> 
> ... ideas on useful or interesting things to do with them?
> 
> I have 2" OC703 I'm starting to make wall (maybe ceiling) panels with. Currently two 2" panels (2.5" frames) hang on side-wall first reflection (just in front of the row of seating) - on diagram, black with red border
> 
> I'm also thinking I'll put in a ceiling cloud : on diagram, has yellow border
> 
> Most of the ceiling is 9' and all speakers are hug at about 7.5' ... Atmos ceiling speakers (A) are at 9'
> There is very little space behind the main speakers behind the AT screen - thought maybe using the Armstrong panels there - will they make a difference being only 1" thick?
> 
> interested in your thoughts on where treatments should go and what to do with the 1" Armstrong panels.
> 
> thx!
> 
> thx


No help? 

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## oneartist

Using Owens Corning 703 2" panels, I'm putting 4" thick panels in 1X6 pine frames behind Open Baffle Rythmik subs and 2" panels in 1X4 pine frames behind Maggie 3.6 speakers. I'm covering the frames and panels with Magnepan speaker cloth to match the speakers. I would like to seal the fiberglass surfaces so it does not migrate into the room. I'm thinking of mixing some powdered wall paper glue and brushing that on the fiberglass. I don't think it would turn the panels into reflective surfaces. Another possible solution would be to spray a light coat of 3M spray adhesive on all surfaces.


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## arcticbowman

My 24 OC703 panels arrived. Took them down to the theater and opened them up. When I got back from being out of town, this is how I found them on the porch.










Nobody warned me that the panels would smell like decaying salmon on the side of the road once the packages were opened up. A quick google search informed me this was common and the smell should go away in a couple days to a couple of weeks. I can still smell a hint of it on the panels, but I think it is mostly aired out now.

I have the bulk of the framing done behind the speakers to insert 9 of the panels. I used standard 2X4's with 2X2's placed above and below them to hold the panels 1.5" off the back wall for an air gap. They fit perfectly flush and I'll be placing a 100% black polyester fabric over the panels after they are installed.










If there are any comments or suggestions on the direction I'm headed with this, it would be greatly appreciated.


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## Mpoes12

*When Soundproofing is acoustic treatment*

I don't hear this discussed on the forums much, and in fact, when I brought it up with Ted from the Sound Proofing company he commented he is a sound proofing guy and not an acoustics guy. The common technique we use of creating decoupled damped walls is actually an acoustic treatment approach as well. The theory as to why is very rational and sound, but I've hardly ever heard mention of it. I know that Nyal Mellor of Acoustic Frontiers talks about this, as does Dr. Earl Geddes, and Dr. Peter D'Antonio. Why isn't this discussed more here? I think its a pretty important concept.


When using tuned bass traps we typically target problem frequencies, but with the walls of our theater we could not easily do that. I suppose with a BEM analysis of the wall structure itself we might be able to first predict the problem areas and then predict the tuned frequency of the walls, but I suspect hitting those tuned frequencies would be really hard. None the less, the Low Q of the resonant frequency of the walls is probably sufficient to provide fairly broad LF damping. 


This also makes me think that intentionally varying the walls depths, insulation density, rigidity, etc. might also help create a broader set of frequencies that we have optimal damping for. When I talked with Dr. Geddes about this he said that while the concept is known to be true, it hasn't been studied extensively. Mostly because its really hard to test this in a lab in a meaningful way. As a result it is not possible to know or even guess the amount of LF damping available using this technique. He mentioned that his own dissertation noted that it doesn't really matter if you have one or two wall pairs treated, the effect was the same. His point was that you don't need symmetric bass damping in a room, the room doesn't care, the bass will be damped just the same (that is, if one wall has twice the damping of two individual walls, it will damp the bass in the room the same as if you did two walls with half the damping. Obviously more damping means more damping).


In my theater I had a few fortuitous changes to my theater design that has created 4 walls and a ceiling that are all decoupled CLD walls with different cavity depths, insulation levels, and rigidity. I plan to do some testing of the room using my accelerometer on the wall surfaces at various locations to see if I can pinpoint a resonant frequency and Q for either the whole wall or section of the wall. I have a feeling the wall doesn't always act as one structure at all frequencies and will show more than one resonance. I suspect as frequencies become lower the wall/room boundaries begin to act as more and more of one structure, but I'm not sure my test would show that. I would have loved to test the room's LF damping caused by the construction but that is not possible. Even if I tested the room before the theater was built it would not have shown anything meaningful, since the room's boundaries and volume and changed drastically. 


If anyone has any other ideas of how to test this, that would be great. One thing I'm really curious about is where the damping effect stops and additional bass trapping becomes necessary. My assumption is that this only works at fairly low frequencies, but where does it stop? 30hz? 60hz? 100hz? Those all make a big difference. The amount of velocity absorption or additional tuned absorbers needed are drastically different for each of those scenarios. What if it actually is effective right on up to 200-300hz? Then you could get away with modest 4" or 6" velocity absorbers in some key locations and not need to waste much space with true bass trapping.


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## HTaddiction

Acoustic recommendations

Hello, I have a separate thread but thought I'd try here as well.

So I have a soon to be spare room in my home that I'll be transforming into a theater room. The layout is interesting, kinda square I guess with vaulted ceilings. Angles from 8ft up to 12ft. There's also a cove in the room with 3 large windows that take up alot of wall on the right side. Cant do panels there so thinking heavy curtains. Attached is a diagram of my plans. I kinda slapped it together but the important info is there.

Red triangles represent potential corner traps using roxul safe n sound wall to ceiling. I also may build a 12" x 16" soffit trap in the cove ceiling since I'll have plenty of roxul material laying around. I also currently have 7 2'x4' & 7 2'x2' of 2" owens 703 panels that's framed and wrapped already for use. Room has heavy thick carpet already. Installing a 7.2 system in there.


From hours of researching I'm thinking of using kraft paper or FRK on all bass traps and using my 2" 703 panels at first reflection areas?

Should I treat the ceiling at all or leave it as is? 

Any thoughts on this layout and plan would be appreciated. Thanks


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## Mpoes12

I can't seem to open your diagram. Can you share the room dimensions and the distances between the listening position and each wall? That would help.


My knee jerk reaction is that a square room is generally a bad room for acoustics but you make the best of what you got. I'm just completing my theater build, but had been using a converted bedroom that was 11' by 12' by 8'. This isn't square but the modes end up being very close together. My biggest cancelations were caused by the tangential length/width modes, causing a suckout between 100hz and 200hz. That was with 3 subwoofers optimally distributed and setup. My biggest problem was my seating position was against the rear wall.


What I find is that moving your listening position to roughly 1/3 of the way into the room from the rear wall (for very small square shaped rooms) and the front speaker 1/4 of the way into the room from the front wall you get more even bass. Doing that increases the early reflections off the front wall behind the speakers. This makes controlling of that important. In my case, I have CD speakers and the 90 degree dispersion of the speaker from 1000hz up meant a lot less energy was hitting the wall. My projector screen was on the wall, which left no room for acoustic treatment however. This isn't ideal, you want to treat that wall.


Most of your work is going to be broadband, even with the paper facing of the bass traps, and so you will be absorbing a lot of energy in that room. I normally don't like that approach, but I do find in small rooms its better. Diffusion is too hard if not impossible to get right in small spaces. 


What are your plans for bass? In small spaces you will find that the bass is hard to get right in some ways and easy to get right in others. For example, you get the benefit of room gain earlier if the small space is also well sealed, but you have a lot more modes higher up in the bass range, above where the subwoofers can aid in smoothing the response. On the other hand, their higher frequencies also make them easier to address with traps. None the less, most traps, even corner traps, aren't providing a ton of absorption where these modes are happening. You would have to cover every surface of the room with a foot or more of acoustic absorption material to really mitigate the problem. I find a better solution is some absorption selectively placed and most time focused on things like multiple subwoofers and critical placement of the listener.


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## HTaddiction

Mpoes12 said:


> I can't seem to open your diagram. Can you share the room dimensions and the distances between the listening position and each wall? That would help.


Hmmm, I'll try reposting the diagram and hopefully your able to open it. If not perhaps I could email it to you. The room is sorta 15 x 15 but has lots of angles. No two walls are the same length. I can play with the seating area a bit but for now let's just say i'll be 6ft from back speaker, 7ft from sides and 8ft from fronts.


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## Mpoes12

Your drawing seems to suggest it's a 11' by 12' room. Am I reading it wrong?


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## Mpoes12

Does the room have a door? If so is it solid or hollow core? How about the wall construction? Is it 5/8" or 1/2" drywall? If neither is it lathe and plaster? How sealed would you say the room is? This all impacts if the bass will see the walls as true boundaries or not at certain frequencies. 

The slant is not in the direction I expected it's not ideal for sound. Would you be open to treating the ceiling?

What kind of speakers will you use?

I'll be honest this is a challenging room. I think it might need some careful matching of equipment and reflection control for best sound. The ceiling reflections on the left side will be much different than the right. The wall reflections aren't symmetric. This all can negatively impact the sound, especially staging. 

Are you open to placing the second subwoofer somewhere else? Possibly behind the couch?


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## HTaddiction

Mpoes12 said:


> Does the room have a door? If so is it solid or hollow core? How about the wall construction? Is it 5/8" or 1/2" drywall? If neither is it lathe and plaster? How sealed would you say the room is? This all impacts if the bass will see the walls as true boundaries or not at certain frequencies.


Yes double doors behind the planned main sitting area. They're hollow. Walls are drywall not sure of thickness. The front wall is 12'10" but the is a cove on the right wall which takes the center of the room to 14'10". The left wall measures 11', then slants inward for 5' which creates that 9' wall in the back. It's just a weird shaped room.



Mpoes12 said:


> The slant is not in the direction I expected it's not ideal for sound. Would you be open to treating the ceiling?


I figured as much. What would your ceiling suggestions be?



Mpoes12 said:


> What kind of speakers will you use?


Energy Conn. series. The older ones. C-9 towers, C-C3 center, C-3 sides, bipole C-R1 backs. 2 12" SVS PB-2000



Mpoes12 said:


> I'll be honest this is a challenging room. I think it might need some careful matching of equipment and reflection control for best sound. The ceiling reflections on the left side will be much different than the right. The wall reflections aren't symmetric. This all can negatively impact the sound, especially staging.
> 
> Are you open to placing the second subwoofer somewhere else? Possibly behind the couch?


Yup, shouldn't be a problem if necessary. Would love to keep them where placed but I know it's best to place in optimal location.


Sent from my iPhone using Tapatalk[/QUOTE]


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## Mpoes12

Optimal placement of the subwoofers is often not having them all upfront if you want the flattest bass response. With out a BEM model of your room it's hard to predict the best location of the subwoofers. It might be worth trial and error. I'd suggest trying them with one in the front corner and one in the rear about a quarter in. 


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## Mpoes12

Sorry I'm responding piece meal here. Ok given your wall construction and room type I have a few suggestions. First I should say that without measurements or modeling of the room it is very possible that these suggestions are wrong. I'm giving you generalizations that might help improve the sound. 

I think a cloud type absorber spaced away from the ceiling will help with the ceiling reflections. How you hang it is up to you, but you might consider hanging it level so that the hanger length is longer on one side than the other. You could use four pieces of 2x4 oc 703 if you like for this. Make a frame to hold all of it into a 4x8 panel. 

Treat the sidewalls as you intend with OC on the walls at the first reflection points and a curtain where the windows are. Remember to choose a curtain that is likely to have good acoustic properties such as heavy velvet. You could also line the curtain with an insulating layer. It's surprising how good a curtain can insulate due to its airspace from the wall. I want to say that a heavy velour has an absorption coefficient above .5 at frequencies over 250hz. If you add a thick insulating layer like a quilted liner you can expect to see that low end drop to 125hz or so where it stays over .5 and likely exceeding .7 or so in the midrange. It's distance from the wall also impacts the low end absorption, use a rod that spaces it 6" from the wall or so to have good low end absorption. 

As I mentioned in small rooms I find you often sit too close to diffusers for them to be helpful, but I still like to have some scattering and diffusion. I like MLS panels and find they keep the room alive while not having audible artifacts up close. 

Don't forget to add an airspace for your OC panels if you can handle it looks wise. 2" panels behave like 4" panels if you give them a 2" air gap from the wall. When seeking broadband absorption a perfect absorber would absorb equally at all frequencies. However what happens in most rooms is that your wall surfaces are practically reflection free in the midrange and lower treble, but allow bass to largely pass through or reflect untouched. Very high frequencies actually start to scatter instead of absorb. You end up with uneven absorption where you really don't want it. The main reason people add so many bass traps is that you want anechoic response in the bass but you don't want that everywhere else. In a room like yours you want as much absorption as you can get below 150-200hz, but to get that you will end with too much absorption in the midrange. 


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## HTaddiction

Mpoes12 said:


> Sorry I'm responding piece meal here. Ok given your wall construction and room type I have a few suggestions. First I should say that without measurements or modeling of the room it is very possible that these suggestions are wrong. I'm giving you generalizations that might help improve the sound.
> 
> I think a cloud type absorber spaced away from the ceiling will help with the ceiling reflections. How you hang it is up to you, but you might consider hanging it level so that the hanger length is longer on one side than the other. You could use four pieces of 2x4 oc 703 if you like for this. Make a frame to hold all of it into a 4x8 panel.
> 
> Treat the sidewalls as you intend with OC on the walls at the first reflection points and a curtain where the windows are. Remember to choose a curtain that is likely to have good acoustic properties such as heavy velvet. You could also line the curtain with an insulating layer. It's surprising how good a curtain can insulate due to its airspace from the wall. I want to say that a heavy velour has an absorption coefficient above .5 at frequencies over 250hz. If you add a thick insulating layer like a quilted liner you can expect to see that low end drop to 125hz or so where it stays over .5 and likely exceeding .7 or so in the midrange. It's distance from the wall also impacts the low end absorption, use a rod that spaces it 6" from the wall or so to have good low end absorption.
> 
> As I mentioned in small rooms I find you often sit too close to diffusers for them to be helpful, but I still like to have some scattering and diffusion. I like MLS panels and find they keep the room alive while not having audible artifacts up close.
> 
> Don't forget to add an airspace for your OC panels if you can handle it looks wise. 2" panels behave like 4" panels if you give them a 2" air gap from the wall. When seeking broadband absorption a perfect absorber would absorb equally at all frequencies. However what happens in most rooms is that your wall surfaces are practically reflection free in the midrange and lower treble, but allow bass to largely pass through or reflect untouched. Very high frequencies actually start to scatter instead of absorb. You end up with uneven absorption where you really don't want it. The main reason people add so many bass traps is that you want anechoic response in the bass but you don't want that everywhere else. In a room like yours you want as much absorption as you can get below 150-200hz, but to get that you will end with too much absorption in the midrange.
> 
> 
> Sent from my iPhone using Tapatalk


Okay, very good suggestions. I will add the ceilings to my list of treatment as well as the curtains. 

Couple of questions if you don't mind.

1. I'm inexperienced to room acoustics, obviously, so what tools would I use for room measurements? (REW)? As long as it's DIY and not too costly, I have no problem spending time educating myself.

2. I'm a little confused regarding bass traps. I thought FRK faced traps would reflect the higher frequencies to avoid over damping mid & high range? Would you suggest I change something with the bass traps?

I appreciate your help. Room acoustics seem to be interesting but complicated since each room has it's own individual needs. Guess I have a lot more reading to do.


----------



## Livin

I just inherited 10 panels of Armstrong Ceilings Shasta White Textured 15/16-in Drop Acoustic Panel Ceiling Tiles (Common: 48-in x 24-in)

... ideas on useful or interesting things to do with them?

I have 2" OC703 I'm starting to make wall (maybe ceiling) panels with. Currently two 2" panels (2.5" frames) hang on side-wall first reflection (just in front of the row of seating) - on diagram, black with red border

I'm also thinking I'll put in a ceiling cloud : on diagram, has yellow border

Most of the ceiling is 9' and all speakers are hug at about 7.5' ... Atmos ceiling speakers (A) are at 9'
There is very little space behind the main speakers behind the AT screen - thought maybe using the Armstrong panels there - will they make a difference being only 1" thick?

interested in your thoughts on where treatments should go and what to do with the 1" Armstrong panels. 

Thx for the help


----------



## Mpoes12

HTaddiction said:


> Okay, very good suggestions. I will add the ceilings to my list of treatment as well as the curtains.
> 
> 
> 
> Couple of questions if you don't mind.
> 
> 
> 
> 1. I'm inexperienced to room acoustics, obviously, so what tools would I use for room measurements? (REW)? As long as it's DIY and not too costly, I have no problem spending time educating myself.
> 
> 
> 
> 2. I'm a little confused regarding bass traps. I thought FRK faced traps would reflect the higher frequencies to avoid over damping mid & high range? Would you suggest I change something with the bass traps?
> 
> 
> 
> I appreciate your help. Room acoustics seem to be interesting but complicated since each room has it's own individual needs. Guess I have a lot more reading to do.




REW is a good free software. Spend some time using it, its helpful. The USB measurement Mics from parts express and minidsp are the easiest to use and more than accurate enough to use for this purpose. I don't happen to use this so I can't give any first hand experience. 

I would suggest using your measurements for bass integration rather than taking full range measurements and trying to interpret what's going on in the stochastic region. A lot of people use waterfall plots to look at the effect of bass traps. 

As for FRK, it does reduce the high frequency absorption and increase low frequency, being highly reflective at high frequencies. However it's still paper and of low mass. It still lets a good deal of midrange pass through and only helps the bass so much. It certainly is the cheapest and safest way to increase bass absorption but it won't guarantee you don't dry out the rooms acoustics. This is why I suggest wood panel fronts to add some mid and high frequency scattering. Their mass helps increase bass absorption too. 

I still think the best approaches are bass traps using tuned membranes but they are harder to DIY and must be matched to measured modes in the room and precisely placed. Since you are new to this it's safer to stick with your plan. 

I've not mentioned this but in case it's an option, the best way to treat the room is to rebuild it. Tearing out your drywall and building a decoupled CLD wall provides significant of damping. It's the best and most significant way to add of damping to a room, turning the entire wall into a bass trap. 

Another option is to treat the ceiling in such a way as to provide a lot of the bass absorption and ceiling reflection control. You could potentially run channels across your ceiling and fill the spaces in the channels with fiberglass insulation. Then cover the surface with fabric. Better yet add wood strips to make it a scattering surface at high frequencies. If you precisely space the slats it also acts as a helmholtz resonator at very low frequencies while still providing more broad absorption into the lower midrange and scattering above that. Most people don't have the ceiling height for this but you could do this. 


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## Mpoes12

Livin said:


> I just inherited 10 panels of Armstrong Ceilings Shasta White Textured 15/16-in Drop Acoustic Panel Ceiling Tiles (Common: 48-in x 24-in)
> 
> ... ideas on useful or interesting things to do with them?
> 
> I have 2" OC703 I'm starting to make wall (maybe ceiling) panels with. Currently two 2" panels (2.5" frames) hang on side-wall first reflection (just in front of the row of seating) - on diagram, black with red border
> 
> I'm also thinking I'll put in a ceiling cloud : on diagram, has yellow border
> 
> Most of the ceiling is 9' and all speakers are hug at about 7.5' ... Atmos ceiling speakers (A) are at 9'
> There is very little space behind the main speakers behind the AT screen - thought maybe using the Armstrong panels there - will they make a difference being only 1" thick?
> 
> interested in your thoughts on where treatments should go and what to do with the 1" Armstrong panels.
> 
> Thx for the help




Of course they will make a difference. They are going to absorb higher frequencies well and lower midrange to bass poorly being so thin. Can you space them from the wall to give a 1" or 2" air gap?


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## Ricoflashback

HopefulFred said:


> Everything could be said to be absorptive, reflective, and diffusive at some frequencies and to some extent; however, for your purposes the answers to both your questions are "no." For most audible frequencies, both of those surfaces should be considered reflective.


As I am learning more about sound and acoustic treatments, I really appreciate your straight forward comments about everything being absorptive, reflective or diffusive. (This will be on the mid-term exam!)

These three concepts seem fundamental towards understanding the room you want to treat. And, if you can start with a blank canvas -- the better.

Can you recommend companies out there that can help you with this project at a reasonable cost?

I've seen GIK Acoustics website and was very impressed with their approach. Any others?

P.S. - can you also soundproof a home theater (walls - not ceiling as this is a ranch home) in addition to acoustically treating your home theater room? Any caveats to doing this?


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## HTaddiction

Mpoes12 said:


> As for FRK, it does reduce the high frequency absorption and increase low frequency, being highly reflective at high frequencies. However it's still paper and of low mass. It still lets a good deal of midrange pass through and only helps the bass so much. It certainly is the cheapest and safest way to increase bass absorption but it won't guarantee you don't dry out the rooms acoustics. This is why I suggest wood panel fronts to add some mid and high frequency scattering. Their mass helps increase bass absorption too.


Is there a particular type of wood to use? Should it be glued as FRK or kraft paper would?

Okay after doing some reading I believe you are referring to flat wall traps that use 1/8 plywood followed by slight air gap then a layer of fiberglass. Is this correct? 




Mpoes12 said:


> Another option is to treat the ceiling in such a way as to provide a lot of the bass absorption and ceiling reflection control. You could potentially run channels across your ceiling and fill the spaces in the channels with fiberglass insulation. Then cover the surface with fabric. Better yet add wood strips to make it a scattering surface at high frequencies. If you precisely space the slats it also acts as a helmholtz resonator at very low frequencies while still providing more broad absorption into the lower midrange and scattering above that. Most people don't have the ceiling height for this but you could do this.
> 
> 
> Sent from my iPhone using Tapatalk


This is an interesting idea. I know it would be difficult to answer without measurements, but would such a treatment potentially alleviate the need for corner traps? 

Kind of a side question here. I've read that the back wall should use treatment to cut down on reflection. Perhaps 2" 703 placed behind the front 3 speakers?


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## HopefulFred

Ricoflashback said:


> Can you recommend companies out there that can help you with this project at a reasonable cost?
> 
> I've seen GIK Acoustics website and was very impressed with their approach. Any others?
> 
> P.S. - can you also soundproof a home theater (walls - not ceiling as this is a ranch home) in addition to acoustically treating your home theater room? Any caveats to doing this?


I'm not familiar with the various consultants and services available. Glenn seems to be really good and has a reputation to be reasonably priced, I think; but I couldn't offer any comparison.

Soundproofing is a whole ball of wax that deserves careful consideration and should, IMO be used for any serious home theater. There is a sticky thread like this one devoted to it.


----------



## Ricoflashback

HopefulFred said:


> I'm not familiar with the various consultants and services available. Glenn seems to be really good and has a reputation to be reasonably priced, I think; but I couldn't offer any comparison.
> 
> Soundproofing is a whole ball of wax that deserves careful consideration and should, IMO be used for any serious home theater. There is a sticky thread like this one devoted to it.


Much thanks. I found that thread on AVS Forum. Learning about both seems the right approach.


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## Mpoes12

HTaddiction said:


> Is there a particular type of wood to use? Should it be glued as FRK or kraft paper would?
> 
> 
> 
> Okay after doing some reading I believe you are referring to flat wall traps that use 1/8 plywood followed by slight air gap then a layer of fiberglass. Is this correct?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This is an interesting idea. I know it would be difficult to answer without measurements, but would such a treatment potentially alleviate the need for corner traps?
> 
> 
> 
> Kind of a side question here. I've read that the back wall should use treatment to cut down on reflection. Perhaps 2" 703 placed behind the front 3 speakers?




Only treating the ceiling and nothing else for bass is not the best option. It's a boundary like any other wall, but the corners still reflect the best places for trapping. There are some rules of thumb out there that suggest rooms under 500 square foot should dedicate a good 50% of the wall areas to acoustic treatment. I would say this. If you can do a ceiling treatment as I suggested and do the wall behind the speakers to a depth of 8" to 12" deep (and the went corner to corner) then I think you could get away with less treatment else where for bass. This is still a gross generalization and the odd shape of your room may very well creat some hot spots where special trapping could help. It's hard to say. I know that a few studies found that heavily treating one wall was just as effective as treating two walls half as much. That means at bass frequencies you can treat half the room twice as much. By doing the ceiling and front wall you can go with less treatment on the floor and back wall (for bass damping). 

The wall behind the speakers should be treated as should the first reflection points. If you can manage covering the entire wall in acoustic insulation that is actually really a good thing to do. In my theater I have the entire area behind the screen covered in 2" fiberglass and will hang fiberglass wrapped wooden sheets floor to ceiling in the cavity where I have space. In addition the entire screen wall is covered in 2" insulation as well, which is spaced 30" from the wall behind he speakers. That gives significant bass absorption and gives me the option of minimizing damping on the rear wall. Mind you my entire room is also built as a giant bass trap due to its "floppy wall" construction. 

If you can't go all out, that's ok, do what you can. Everyone makes compromises. You will get benefits even if it's not perfect. It may not be an audible difference if it's too little treatment though. 



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## HTaddiction

Mpoes12 said:


> Only treating the ceiling and nothing else for bass is not the best option. It's a boundary like any other wall, but the corners still reflect the best places for trapping. There are some rules of thumb out there that suggest rooms under 500 square foot should dedicate a good 50% of the wall areas to acoustic treatment. I would say this. If you can do a ceiling treatment as I suggested and do the wall behind the speakers to a depth of 8" to 12" deep (and the went corner to corner) then I think you could get away with less treatment else where for bass. This is still a gross generalization and the odd shape of your room may very well creat some hot spots where special trapping could help. It's hard to say. I know that a few studies found that heavily treating one wall was just as effective as treating two walls half as much. That means at bass frequencies you can treat half the room twice as much. By doing the ceiling and front wall you can go with less treatment on the floor and back wall (for bass damping).
> 
> The wall behind the speakers should be treated as should the first reflection points. If you can manage covering the entire wall in acoustic insulation that is actually really a good thing to do. In my theater I have the entire area behind the screen covered in 2" fiberglass and will hang fiberglass wrapped wooden sheets floor to ceiling in the cavity where I have space. In addition the entire screen wall is covered in 2" insulation as well, which is spaced 30" from the wall behind he speakers. That gives significant bass absorption and gives me the option of minimizing damping on the rear wall. Mind you my entire room is also built as a giant bass trap due to its "floppy wall" construction.
> 
> If you can't go all out, that's ok, do what you can. Everyone makes compromises. You will get benefits even if it's not perfect. It may not be an audible difference if it's too little treatment though.
> 
> 
> 
> Sent from my iPhone using Tapatalk


Thank you! I appreciate your time and input.


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## Mpoes12

I've included an RT60 measurement I took using the T20 for extrapolation of the graph. I'm including it just to make a point about acoustic treatment. This was a very small room with completely inadequate LF treatment, but a good amount of mid/high frequency treatment from Vicoustic or DIY. I've cut the low end off because it was mostly garbage. The room had modal ringing and even some panel vibrations from a closet door causing the RT value to skyrocket below 100hz. 


What you can see here is that because I used a mix of treatments to reduce some of the high frequency absorption and maximize the midrange absorption I had a fairly flat RT60 curve from 400hz to 10khz. That's a good thing to have and what you want to shoot for. It was also a fairly perfect .25s RT60 value, which is the target in most theaters. I honestly believe that fixing the LF ringing problem would have required rebuilding the room, its wall construction was too light and rigid for this.


Now that my theater is constructed and I am assembling the equipment in the room, I plan to take some measurements at various stages to look at RT60 values and share those. I also plan to take or obtain measurements from a few friends theaters with different sizes and construction types, along with different levels of acoustic treatment. Hopefully it will make for an interesting set of findings.


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## fingersdlp

Side walls next to front L/R speakers. Absorb or not?

I have a narrow room so the L/R speakers are close to the side walls. I have added black drapes for first 6 feet or so of side wall. These are lined so thicker. I was thinking of removing the liner but I could leave it in for the area adjacent to the speakers. The liner makes it much less acoustically transparent. 

Generally is it better to absorb immediately adjacent to the speakers and then be transparent farther out? I do have acoustic panels farther out on the side walls just after the end of the drapes.

Thanks


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## Nick V

You'll want to treat the first reflection points based on your primary listening position.

If those points are on the wall directly beside the speakers, you're going to want to treat them.

Whether you use diffusion, absorption, or a combination of the two appears to be up for some debate, but you'll want to treat those first reflections. I use absorption.


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## fingersdlp

Nick V said:


> You'll want to treat the first reflection points based on your primary listening position.
> 
> If those points are on the wall directly beside the speakers, you're going to want to treat them.
> 
> Whether you use diffusion, absorption, or a combination of the two appears to be up for some debate, but you'll want to treat those first reflections. I use absorption.


Thanks, so probably leaving the liner in at the reflection points if they fall in the area of the curtain would be best. Even better to make sure my side panels are already positioned as needed.


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## Mpoes12

fingersdlp said:


> Thanks, so probably leaving the liner in at the reflection points if they fall in the area of the curtain would be best. Even better to make sure my side panels are already positioned as needed.


What kind of speakers do you have? Do they have controlled directivity? This matters. Speakers with constant directivity (lets call that a special case of controlled directivity) will have significantly less output to reflect off the wall and can impact where you place treatments. 


Can you give any more information like room width and length, listening position, speaker distance form side wall? 


I really don't think there is much debate about diffusion or absorption, two different tools for accomplishing the same end. I think the debate comes from folks on forums, I've never seen pros debate this much. It seems more people have trouble with diffusion and many people have rooms that are too small for diffusers to be useful. There are people who just prefer a really reverberant free room. They are casually shooting for RT60 values of like .01s instead of .25s. I've never seen a pro intentionally do this. 


For lots of reasons I think its a good idea to have a lot of absorption on and around the front of the room if the room is relatively small. If it is larger, then I like to mix it up myself. I like to have some diffusion. When I first started measuring the impact of my acoustic treatments I did notice that I frequently over treated the high frequencies and I had downward tilting RT60 graphs that shows much lower values at 5khz than at 500hz. I thought that was ok, to be expected. I've since learned you really need to shoot for a flat RT60 down to the Schroeder frequency and lower if possible.


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## fingersdlp

Mpoes12 said:


> What kind of speakers do you have? Do they have controlled directivity? This matters. Speakers with constant directivity (lets call that a special case of controlled directivity) will have significantly less output to reflect off the wall and can impact where you place treatments.
> 
> 
> Can you give any more information like room width and length, listening position, speaker distance form side wall?
> 
> 
> I really don't think there is much debate about diffusion or absorption, two different tools for accomplishing the same end. I think the debate comes from folks on forums, I've never seen pros debate this much. It seems more people have trouble with diffusion and many people have rooms that are too small for diffusers to be useful. There are people who just prefer a really reverberant free room. They are casually shooting for RT60 values of like .01s instead of .25s. I've never seen a pro intentionally do this.
> 
> 
> For lots of reasons I think its a good idea to have a lot of absorption on and around the front of the room if the room is relatively small. If it is larger, then I like to mix it up myself. I like to have some diffusion. When I first started measuring the impact of my acoustic treatments I did notice that I frequently over treated the high frequencies and I had downward tilting RT60 graphs that shows much lower values at 5khz than at 500hz. I thought that was ok, to be expected. I've since learned you really need to shoot for a flat RT60 down to the Schroeder frequency and lower if possible.


Thanks for the detailed info.

I have B&W DM603 S3 for L/R. Room is 12.5 feet wide 18 feet long. Main seating is 14 feet in. Speakers are about 1.5 feet from side walls with about 3-5 percent angle away from side wall. Installed black drapes with liner that come out 4 or 5 feet past speakers. This covers one acoustic panel (I have 4 on each side wall). I could remove the liner to make the drape more acoustically transparent in front of the panel but hence my question. Should I? I can somewhat easily blow air thru the drapes as they are but very easily without the liner. My original question was more about the untreated wall immediately to the outside of the speakers but maybe I should be more concerned with the area over the panel as that is where the first reflection is. 

The first reflection from the speaker on the same side is inside the first panel. I just wonder if the liner is helping or hurting. My guess is it helps over the untreated parts of the wall but is neutral or little effect good or bad over the panel. I am thinking I may leave the liner in unless I hear that is not a good idea.

Thanks


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## Mpoes12

fingersdlp said:


> Thanks for the detailed info.
> 
> I have B&W DM603 S3 for L/R. Room is 12.5 feet wide 18 feet long. Main seating is 14 feet in. Speakers are about 1.5 feet from side walls with about 3-5 percent angle away from side wall. Installed black drapes with liner that come out 4 or 5 feet past speakers. This covers one acoustic panel (I have 4 on each side wall). I could remove the liner to make the drape more acoustically transparent in front of the panel but hence my question. Should I? I can somewhat easily blow air thru the drapes as they are but very easily without the liner. My original question was more about the untreated wall immediately to the outside of the speakers but maybe I should be more concerned with the area over the panel as that is where the first reflection is.
> 
> The first reflection from the speaker on the same side is inside the first panel. I just wonder if the liner is helping or hurting. My guess is it helps over the untreated parts of the wall but is neutral or little effect good or bad over the panel. I am thinking I may leave the liner in unless I hear that is not a good idea.
> 
> Thanks




I don't know what the drapes or liner material are. Velour drapes with a quilted breathable liner typically have very good acoustic absorption. If they are over an acoustic panel, it would just enhance the acoustic absorption further. If it is a reflective material, then it could reflect high frequencies, but it still would likely enhance low frequency absorption. 


Your speakers are not a controlled or constant directivity design and actually would have quite a bit of sound radiating off to the sides. Still, the dome tweeters on speakers of this type ten to beam at high frequencies so they wouldn't have a lot of high frequency side radiation. The primary advantage of adding more treatment to the wall right next to the speakers is probably more about absorbing low midrange and bass. 


Can you take measurements? Can you show an impulse response? in my impulse response my first reflection is at 800u (.8ms) and is reduced 30% points of full scale. That corresponds to a distance of 9.6" which is how far that speaker was to the side wall. Like you, in my old theater, I had the L and R speakers very close to the wall. I did have acoustic treatment, but it obviously can't stop a reflection, only reduce its level, which it did.


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## fingersdlp

Mpoes12 said:


> *Velour drapes with a quilted breathable liner* typically have very good acoustic absorption. If they are over an acoustic panel, it would just enhance the acoustic absorption further. If it is a reflective material, then it could reflect high frequencies, but it still would likely enhance low frequency absorption.


Thanks, that describes them well. I don't have a way currently for measurements. From your feedback I think it is likely they will do some good or no harm so I will leave the liner. I can pull the drapes back and try to compare with/without by ear - probably will not reveal any difference I suspect and more reason to just leave them as is.

I might try to run the room EQ for my receiver with / without the drapes just to see if it has any impact at that level. In any event I should run the room EQ with them in place anyway.

Thanks again!


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## Livin

OC703 2" PANELS... easiest and cheapest way to wrap them. They will be hidden so visuals are not a concern. Would wrapping in a cheap plastic garbage bag be bad? I just want to ensure the fibers don't get everywhere and the acoustic properties still hold. Thx

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## Mpoes12

Livin said:


> OC703 2" PANELS... easiest and cheapest way to wrap them. They will be hidden so visuals are not a concern. Would wrapping in a cheap plastic garbage bag be bad? I just want to ensure the fibers don't get everywhere and the acoustic properties still hold. Thx
> 
> Sent from my SAMSUNG-SM-G935A using Tapatalk




Is this a serious question?

Garbage bags aren't acoustically transparent and would reflect high frequencies. 

If your trying to save money use mineral wool, it's cheaper. 

Burlap is usually the cheapest cover for acoustics. 


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## Mashie Saldana

Livin said:


> OC703 2" PANELS... easiest and cheapest way to wrap them. They will be hidden so visuals are not a concern. Would wrapping in a cheap plastic garbage bag be bad? I just want to ensure the fibers don't get everywhere and the acoustic properties still hold. Thx
> 
> Sent from my SAMSUNG-SM-G935A using Tapatalk


The cheapest option is to wrap them in 2-3 layers of garden fleece (the stuff you put on flower beds).


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## JonasHansen

I have a question which I would like to get your input to. When placing basstraps to mitigate front-wall SBIR then it is easy to know where to place them as the quarter wavelength frequency is the same no matter where you are sitting. But with the SBIR from the side walls, where should the treatments be placed? Now the quarter wavelength changes in relation to the listening position. 

How would you determine the placement and problematic frequency when dealing with the side-wall? Do you just look at the difference in direct and reflected path and calculate SBIR-frequency from that?

EDIT: 
When reading on GIK's webpage, they write this:
_If you still have issues,* you can treat the walls directly beside *and/or behind the speakers with appropriate materials to further reduce the intensity of the reflected wave to it’s impact when interacting with the direct wave is minimized. _

I.e. they do not mention listening position but merely the wall right beside the speaker. That is what confused me


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## Mashie Saldana

JonasHansen said:


> I have a question which I would like to get your input to. When placing basstraps to mitigate front-wall SBIR then it is easy to know where to place them as the quarter wavelength frequency is the same no matter where you are sitting. But with the SBIR from the side walls, where should the treatments be placed? Now the quarter wavelength changes in relation to the listening position.
> 
> How would you determine the placement and problematic frequency when dealing with the side-wall? Do you just look at the difference in direct and reflected path and calculate SBIR-frequency from that?
> 
> EDIT:
> When reading on GIK's webpage, they write this:
> _If you still have issues,* you can treat the walls directly beside *and/or behind the speakers with appropriate materials to further reduce the intensity of the reflected wave to it’s impact when interacting with the direct wave is minimized. _
> 
> I.e. they do not mention listening position but merely the wall right beside the speaker. That is what confused me


SBIR is not the same thing as first reflection point. So in this case it is the walls that will reflect the sound directly back to the speaker itself that needs treating.


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## JonasHansen

Mashie Saldana said:


> SBIR is not the same thing as first reflection point. So in this case it is the walls that will reflect the sound directly back to the speaker itself that needs treating.


So if I understand you correctly, side wall SBIR for a given speaker is not a function of seating position? It is only the speaker and the near surrounding boundaries which is affecting?


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## Mashie Saldana

JonasHansen said:


> So if I understand you correctly, side wall SBIR for a given speaker is not a function of seating position? It is only the speaker and the near surrounding boundaries which is affecting?


Correct, all boundaries in a small room. This is why baffle walls are very popular as they are the easiest SBIR fix.


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## JonasHansen

Mashie Saldana said:


> Correct, all boundaries in a small room. This is why baffle walls are very popular as they are the easiest SBIR fix.


So all boundaries or only near-surround boundaries? Let's say LCR speakers are crossed over at 80hz, are the important treatment areas for SBIR (no matter seating position) all boundaries ~4 feet from the speaker? (Longer distances push the frequency below the crossover).

Baffle wall is ideal for front wall - my questions are related to the side wall where the difference between direct and reflected signal is dependent on seating.

Sorry for my confusion, but you are saying correct when I write "Near surround boundaries" and then write "all boundaries" in your response. Just trying to get my head around it.


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## Mashie Saldana

JonasHansen said:


> So all boundaries or only near-surround boundaries? Let's say LCR speakers are crossed over at 80hz, are the important treatment areas for SBIR (no matter seating position) all boundaries ~4 feet from the speaker? (Longer distances push the frequency below the crossover).
> 
> Baffle wall is ideal for front wall - my questions are related to the side wall where the difference between direct and reflected signal is dependent on seating.
> 
> Sorry for my confusion, but you are saying correct when I write "Near surround boundaries" and then write "all boundaries" in your response. Just trying to get my head around it.


My reply was based on full range speakers. If the speaker in question isn't producing the troublesome frequency it is nothing to fix. So yes only treat the walls with in frequency range.


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## Mpoes12

Mashie Saldana said:


> Correct, all boundaries in a small room. This is why baffle walls are very popular as they are the easiest SBIR fix.




Mashie are you suggesting that SBIR is not a function of seating position, meaning where you are located as a listener in the room does not impact the appearance of an acoustic interference from a near boundary to a speaker? If so that is not totally correct, your seating position absolutely would change the appearance of this "SBIR" with some positions not showing it at all. SBIR is caused specifically by sound bouncing off a near by boundary (including the rear wall) and then hitting the listener at a different time from the direct sound. If it is out of phase then the sound causes a dip. If it is in phase it causes a peak. Your position can change the relative distance between the boundary, source, and you which can change the impact. I imagine you already know this (though others may not). Where I think the notion that SBIR is seat independent is because the boundaries and speaker position are fixed and the offending frequencies are low in the omni area of radiation. That means the difference in distance between the direct sound and reflected sound has a fixed difference in distance. That is true at the point of the speaker. That is not true as you move around the room. For example, if we consider the triangle made between the listener, speaker, and rear wall boundary, as we move left or right in the room, the length of the lines between speaker and listener and boundary and listener change such that their relative distance is different as well. In addition, you can intentionally choose a position where the distance is such that it does not create a negative impact (any destruction is beneficially for instance). 


Unlike sidewall reflections where you treat the sidewall at a different position based in your listening position (which is only due to the more "ray" like behavior of waves at higher frequencies), with SBIR you are treating the entire boundary regardless of your position. 


I've always taken issue with the notion that treating the first reflection point is as simply as putting a 2'x4' panel at a position where sound magically hits the sidewall and bounces off to hit the listener at a delayed time, as if this is just one point in space on the wall and that all speakers behave in the same way. In reality, I believe this first reflection point differs based on the speakers own radiation pattern, how its positioned, and the frequency of interest. In small rooms all speakers have spherical radiation at low frequencies, but then they also don't have a "first" reflection point on the side wall, you wouldn't treat that. At higher frequencies they are directional and how directional depends on the design. CD speakers "should" be aimed to cross in front of the listener and this would minimize sidewall reflections. In fact the point on the wall that would have the strongest first reflection would be in a very different place. The typical first reflection point position that is chosen for a typical direct radiating speaker would actually have very little sound radiation from a CD speaker with good CD behavior down to say 1khz or below. This is why I usually ask people what speakers they have and where they are positioned, it changes the advice I would give with regard to first reflection treatment. 


I'd actually go so far as to say that really good CD speakers that behave close to ideally positioned optimally would in fact not need sidewall treatment at all. There would be no meaningful first reflection to treat. One common exception is that these speakers would need ceiling first reflection treatment still since we typically would not aim speakers downward (nor are floors typically absorbent enough to count).


----------



## Mpoes12

JonasHansen said:


> So all boundaries or only near-surround boundaries? Let's say LCR speakers are crossed over at 80hz, are the important treatment areas for SBIR (no matter seating position) all boundaries ~4 feet from the speaker? (Longer distances push the frequency below the crossover).
> 
> Baffle wall is ideal for front wall - my questions are related to the side wall where the difference between direct and reflected signal is dependent on seating.
> 
> Sorry for my confusion, but you are saying correct when I write "Near surround boundaries" and then write "all boundaries" in your response. Just trying to get my head around it.




SBIR is caused by low frequencies which are best treated by bass trapping of the boundaries near to the speaker. In reality, this is an issue that is best addressed by having a significant amount of absorption in the room, especially in small rooms. Baffle walls only treat one cause of the so called SBIR. I'd also note, not all acousticians like or use this term. I've mentioned it to a few who just looked at me funny or have noted its just a special case of interference and doesn't need or deserve a special name. Baffle walls treat the boundary effect of a speaker placed close to a back wall. However, it will not treat interference caused by reflections off the ceiling, floor, or sidewalls. This is why I think you need to treat ALL boundaries around the speaker for bass. How you treat the midrange or high's is a different issue and wouldn't fall into SBIR anyway. I can't speak for the other author, but for myself, I'd agree with the notion that you treat all boundaries for low frequency absorption that are near the main speakers. That would include sidewalls still. 


There are sometimes notches in the response blamed on SBIR that are not SBIR in the way GIK defines it. At least I don't believe so. The reason I would make such an argument is that we see these notches blamed on SBIR and happen to roughly match something like the distance between the main speaker and rear wall. Then we note that in fact it also matches a width or length mode. Further we note that the main speakers have no significant output at that frequency in question and the subwoofers placement would not excite that mode due to its distance to a wall, but would due to the rooms length or width. I think this is what you are talking about when you say only treat above the crossover. That is kind of correct, but you still would want to fix that notch, right? The problem is that significant modal interference in a room is not easily treated by a few 6" deep bass traps on the wall or some corner traps. Even "superchunks" often do very little, especially when at very low frequencies. Fixing them ends up being a process of subwoofer quantity, location, tuning, room design, wall construction, and bass trapping in the traditional sense.


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## Mpoes12

I also wanted to make a point. I'm attaching a WinISD model of my midbass drivers in two enclosures as well as a same enclosure with 80hz 2nd order high pass filter (which matches most receivers).










What you see is a yellow line that is a B&C 12TBX100 in a box with a Q of .4 and a -3db of 65hz. The Red line reflects the same driver in a box with a Q of .7 and a -3db point of 120hz. Then we have the green line that reflects the Q.4 box with an 80hz highpass filter. A box by nature is a natural high pass filter and we can see that the slope changes slightly with higher Q boxes, but nothing is as steep as the electrical high pass filter model. Clearly that box is producing a lot less output than the others below 100hz. However, the important thing to note here is that all of these boxes still produce output below their F3 point or the point of the high pass filter. The green line is averaging 114db's above 200hz but is still 95db's at 50hz. 


Now lets look at the same graphs but with the impact of a mode at 50hz causing a peak of 10db's. 










Now notice that the mode has raised the output of the speaker so that at 50hz its 107db's for the green line, which is just 7db's below the speakers average output of 114db's. If we add the response of the subwoofer, which may not be impacted by this 50hz mode due to its location. we can now end up with a peak in the response at 50hz caused by the main speakers, even though they are crossed over at 80hz. Because these crossovers aren't brick walls (nor should they be) we still need to consider the potential contribution of the main speakers below their crossover point. The main speakers can still excite modes that cause problems, even if the subwoofer is optimally placed to avoid that. This is also why PEQ's of the sub sometimes don't have the desired effect, its not the offender. It can bring it down some, but if the PEQ is -10db's and you have two main speakers exciting the same mode causing a peak of 15db's, the PEQ on the sub may not be enough to fix it. .


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## nandkisham

*Ceiling Acoustics - Dead??*

I am planning for a Fiber Optics star Ceiling (8' x16') and intend to run the strands through 2" OC 703 panels covered in fabric with 1" ceiling air gap.
The actual ceiling area is 13 x 22 with vaulted ends at sides and front.

Questions, concerns and any tips?

1) Is that too much absorption leading to detrimental effects?
2) Can I use a 1/8" card backer boards for these panels and still have the 1" inch air gap. The backer board helps to get a glue the strands in place.

Regards,
NJ


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## Mpoes12

Using a lot of absorption on the ceiling is usually a good thing. It's one of the most neglected areas in need of treatment. If anything I'd say do more, go with 2" air gaps. Adding a hard backer board changes things. The air gap no longer will contribute significantly to the LF absorption because the card is in the way. However, that "card" material may not be rigid enough to reflect a lot and in fact may increase LF absorption. It's really hard to say without knowing what it is and doing some tests.

Some folks treat studio ceilings with cloud panels that are hard backed as a means to reflect sound away from the listener. They angle them such that the reflections hit behind the listener are are absorbed or diffused by treatments on the back walls. I've never seen this approach used in a theater before, but see no reason why it can't be. However then your ceiling would have to be angled if you wanted to take advantage of that. I guess my knee jerk reaction is that your proposal isn't a big deal, shouldn't cause any negatives. The only problem you might have is that the hard backer might have a negative effect on the acoustics, but it would be no worse than if you had no treatment. If anything it should be better. I also think it is possible that the hard backer might increase LF absorption, depending on how hard it really is.


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## nandkisham

Mpoes12 said:


> Using a lot of absorption on the ceiling is usually a good thing. It's one of the most neglected areas in need of treatment. If anything I'd say do more, go with 2" air gaps. Adding a hard backer board changes things. The air gap no longer will contribute significantly to the LF absorption because the card is in the way. However, that "card" material may not be rigid enough to reflect a lot and in fact may increase LF absorption. It's really hard to say without knowing what it is and doing some tests.
> 
> Some folks treat studio ceilings with cloud panels that are hard backed as a means to reflect sound away from the listener. They angle them such that the reflections hit behind the listener are are absorbed or diffused by treatments on the back walls. I've never seen this approach used in a theater before, but see no reason why it can't be. However then your ceiling would have to be angled if you wanted to take advantage of that. I guess my knee jerk reaction is that your proposal isn't a big deal, shouldn't cause any negatives. The only problem you might have is that the hard backer might have a negative effect on the acoustics, but it would be no worse than if you had no treatment. If anything it should be better. I also think it is possible that the hard backer might increase LF absorption, depending on how hard it really is.


Thanks for the response @Mpoes12.


This is the HardBoard I was referring to use the 
http://www.homedepot.com/p/Hardboar...0-115-in-x-47-7-in-x-95-7-in-832777/202046928

See attached images to view my concept..


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## Mpoes12

Yeah it will potentially reduce some of the midbass absorption and may even reflect some sound at a significantly reduced level. It may raise the low frequency absorption some. It's hard to say. 

I know of a studio designer that likes to back OC703 with hardboard to reflect attenuated sound waves and he angles them so that the sound is redirected behind the listener. It can't be all bad of he's doing it as a professional. 


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## JWL.GIK

Nice post. Boundary Interference is just one of the factors at play for most of us trying to get good sound in smaller rooms. Usually there are two ways to combat it: either move the speakers, or put a bass trap in the path the reflected low end takes to get back to the speaker. SBIR is often problematic with a big null between 100-200Hz, if the speakers are between 18-36" from a wall. These strategies can help, but should only be a part of the overall bass management strategy. 

Speaking of which, I don't agree that bass trapping (such as superchunks) do very little. If they are implemented correctly in a good bass trapping strategy, the improvement is not subtle. That said, yes you do need a lot of broadbass trapping to solve very low frequency issues (under, 60Hz, say). 





Mpoes12 said:


> SBIR is caused by low frequencies which are best treated by bass trapping of the boundaries near to the speaker. In reality, this is an issue that is best addressed by having a significant amount of absorption in the room, especially in small rooms. Baffle walls only treat one cause of the so called SBIR. I'd also note, not all acousticians like or use this term. I've mentioned it to a few who just looked at me funny or have noted its just a special case of interference and doesn't need or deserve a special name. Baffle walls treat the boundary effect of a speaker placed close to a back wall. However, it will not treat interference caused by reflections off the ceiling, floor, or sidewalls. This is why I think you need to treat ALL boundaries around the speaker for bass. How you treat the midrange or high's is a different issue and wouldn't fall into SBIR anyway. I can't speak for the other author, but for myself, I'd agree with the notion that you treat all boundaries for low frequency absorption that are near the main speakers. That would include sidewalls still.
> 
> 
> There are sometimes notches in the response blamed on SBIR that are not SBIR in the way GIK defines it. At least I don't believe so. The reason I would make such an argument is that we see these notches blamed on SBIR and happen to roughly match something like the distance between the main speaker and rear wall. Then we note that in fact it also matches a width or length mode. Further we note that the main speakers have no significant output at that frequency in question and the subwoofers placement would not excite that mode due to its distance to a wall, but would due to the rooms length or width. I think this is what you are talking about when you say only treat above the crossover. That is kind of correct, but you still would want to fix that notch, right? The problem is that significant modal interference in a room is not easily treated by a few 6" deep bass traps on the wall or some corner traps. Even "superchunks" often do very little, especially when at very low frequencies. Fixing them ends up being a process of subwoofer quantity, location, tuning, room design, wall construction, and bass trapping in the traditional sense.


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## Mpoes12

I think we are largely saying the same thing. Treating boundaries effects requires absorbing the reflection or moving the speaker to reduce its effect. My point was that absorbing it's reflection at even 200hz requires a lot of absorption across the entire boundary surface to be what I call highly effective. I also rarely find corner traps to be the solution to these problems. A super chunk is just a big corner trap. 

My biggest problem with this is that if we have a boundary effect causing a 60db dip in the response, which isn't unheard of, then adding damping might be highly effective at reducing the dip from 60db down to just 40db down, but it's still 40db down. And in some cases it also lowers the Q of the dip, which can be audibly worse. That isn't to suggest that adding inadequate low frequency damping is worse than nothing, but I think sometimes the effect is blown out of proportion. If I have a 40db dip or a 60db dip, I don't consider either to be better, I want to fix that until it's minimal. If we are talking about say 120hz, then we are talking about probably 12" of insulation across the entire front and front/side wall before that dip goes away. 


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## JMAX2016

Okay guys, what would it do to the sound absorption if I put velvet over top of a sound absorber? I know I want to use an AT fabric, and I know that velvet is not AT. But what would it actually do to the sound?


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## 12B4A

You'll just get a little more reflectance above 2-3khz.

Edit: I'd wager it would teeter on not noticeable to barely noticeable in this instance.


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## Mpoes12

12B4A said:


> You'll just get a little more reflectance above 2-3khz.
> 
> Edit: I'd wager it would teeter on not noticeable to barely noticeable in this instance.


I'd bet the opposite is true. It will absorb more, not less. 
http://www.rosebrand.com/product1210/32-oz-Magic-Velour-FR.aspx
Rosebrand tested their velour's as acoustic curtains and found them to be highly absorptive when give a good airgap. There is nothing surprising about that. 

Velvet or velour may or may not be acoustically transparent. It would depend on the material. At low frequencies most materials are acoustically transparent, the material lacks the necessary mass to be "seen" by the wave. At high frequencies it can do one of three things. It can be rigid and massive enough to reflect sound. It can be such that the particle's energy is dissipated within the woven fiber and thus the sound is absorbed. It be light and thin enough to essentially allow the particles to pass through unabated. Acoustic transparency means the latter. The question is what effect it will have on sound absorption, and in fact, it is absorptive itself to a point. 

The problem will be the density and openess of the backing material. If the acoustical impedance of the material relative to the fiberglass provides a drastic shift (low to high typically) it will reflect. Sometimes the backing material of these fabrics have a high acoustical impedance and it becomes reflective when sound hits it (even though its surface is absorptive). This seems to be the case with a lot of synthetic suede materials and I think why we see a drop in the absorption of high frequencies for these panels.

What you really want is a gradual shift from lower to higher acoustical impedance as you approach the wall in order to avoid the wave from reflecting before it has traveled through the material.


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## JonasHansen

I'm looking at doing some DIY broadband panels, and would like to have them as efficient as possible in the lower frequencies. I am thinking of a sandwich construction with something like:

2" fiberglass -> Vinyl barrier -> 2" fiberglass.

If I understand the theory correctly, the middle layer should improve the low frequency absorption.
Now my question is, how is it determined what density to choose for the vinyl barrier? The site I am looking at sells 6kg/m2, 7.5kg/,2 and 15kg/m2. I guess the higher weight the lower frequency, but the weight should ensure a "linear" absorbtion coefficient for the whole system.

I am also making the same construction but with a vinyl barrier placed on the face of the panel as well to be used when only LF-absorption is wanted.

Inputs are appreciated!


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## dgkula

*3" 2x4 panels or 1" linacoustic*

Hi,

I'm finally building my first small dedicated room as part of a post-pipe-burst basement remodel. The room is 12 x 14 with 7.5' ceilings. I need to orient the room with the projector/screen along the 12' length owing to requirements to have a door to a mechanical area. I will have 4 seats and a 92 inch screen (accommodating for another door on the front wall). Not ideal given the limited space and access requirements but I will be moving from a mixed use space with windows to a dedicated space with no windows and openings.

I have wired the room for 7.2.9 with in-walls for SL, SR, RL, RR and 4 Atmos speakers in the ceiling. My L/C/R/SW will be cabinets placed around the screen; I don't have room for a false wall and so am not doing an AT screen with false wall. I have a regular Elite fixed screen from my prior multi-use space. I plan to run dual subs to balance room modes. The walls are up and painted dark blue with a black solid ceiling (i.e. sheetrock not drop). The projector is ceiling mounted with 10.5' throw. 

My question is about acoustic treatments. I have tried to read as much as possible but this thread is really hard to get through. Here are my questions:

1. Since I don't have an AT screen, is there any point in treating the front wall? Presently I am not planning to treat the front wall. Most posters do 1" linacoustic but that seems to go with AT screens.

2. For side walls I am torn between 1" linacoustic to 48" height versus four 3" 2 x 4 acoustic panels on each side wall (for a total of 8 panels). Cost is close - with the raw materials from Fabricmate coming in at $200 more than eight completed GIK 3" panels. Other than the aesthetics, is there any reason to go one way over the other? The panels are thicker and would provide 70% of the surface area coverage of the Linacoustic so I'm not sure what would be "better." I need to determine is aesthetics is the only basis for making this decision or if there is another factor to consider.

3. Should I do anything with the rear wall? Many threads discuss diffusion, but my seats are 1" from rear wall which seems too close for diffusion. Some threads talk about not treating the rear wall to have reflections to minimize localization of surrounds. I haven't come to a conclusion yet and would appreciate some guidance.

4. Since I will be running dual subs, is it fair to assume that with DSP/Audyssey will minimize the need for bass trapping?

Thanks very much! Should be up and running in the next 90 days and I will post pics?

David


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## dgkula

Sorry just noticed typos after posting. Cant figure out how to edit my original post.

Wiring the room for 7.2.4.
SW will be in front right corner and rear left corner.
Seats will be 18" from rear wall.


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## ereed

dgkula said:


> Hi,
> 
> I'm finally building my first small dedicated room as part of a post-pipe-burst basement remodel. The room is 12 x 14 with 7.5' ceilings. I need to orient the room with the projector/screen along the 12' length owing to requirements to have a door to a mechanical area. I will have 4 seats and a 92 inch screen (accommodating for another door on the front wall). Not ideal given the limited space and access requirements but I will be moving from a mixed use space with windows to a dedicated space with no windows and openings.
> 
> I have wired the room for 7.2.9 with in-walls for SL, SR, RL, RR and 4 Atmos speakers in the ceiling. My L/C/R/SW will be cabinets placed around the screen; I don't have room for a false wall and so am not doing an AT screen with false wall. I have a regular Elite fixed screen from my prior multi-use space. I plan to run dual subs to balance room modes. The walls are up and painted dark blue with a black solid ceiling (i.e. sheetrock not drop). The projector is ceiling mounted with 10.5' throw.
> 
> My question is about acoustic treatments. I have tried to read as much as possible but this thread is really hard to get through. Here are my questions:
> 
> 1. Since I don't have an AT screen, is there any point in treating the front wall? Presently I am not planning to treat the front wall. Most posters do 1" linacoustic but that seems to go with AT screens.
> 
> 2. For side walls I am torn between 1" linacoustic to 48" height versus four 3" 2 x 4 acoustic panels on each side wall (for a total of 8 panels). Cost is close - with the raw materials from Fabricmate coming in at $200 more than eight completed GIK 3" panels. Other than the aesthetics, is there any reason to go one way over the other? The panels are thicker and would provide 70% of the surface area coverage of the Linacoustic so I'm not sure what would be "better." I need to determine is aesthetics is the only basis for making this decision or if there is another factor to consider.
> 
> 3. Should I do anything with the rear wall? Many threads discuss diffusion, but my seats are 1" from rear wall which seems too close for diffusion. Some threads talk about not treating the rear wall to have reflections to minimize localization of surrounds. I haven't come to a conclusion yet and would appreciate some guidance.
> 
> 4. Since I will be running dual subs, is it fair to assume that with DSP/Audyssey will minimize the need for bass trapping?
> 
> Thanks very much! Should be up and running in the next 90 days and I will post pics?
> 
> David


You want to put bass traps in corners of your room if you can, if not then you need acoustic panels that are 4 inches or more to absorb low frequencies.

You want to find where your first reflection points are and put panels there.

Since you sit close to rear wall you will get alot of reflected sound bounced back to you from your L, C, and R speakers. Pu broadband absorption panels on rear wall.

Dual subs have nothing to do with helping absorbing bass....dual subs are good for 2 things....increase spl, and evens out bass response in the room which in turns to reduce localization issues.

But ALWAYS treat the first reflection points at least and it would also help if you pull out your couch 1 or 2 feet from your rear wall. When I pulled mine out 3 feet from rear wall the bass became tighter and my decay times improved.


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## Mpoes12

JonasHansen said:


> I'm looking at doing some DIY broadband panels, and would like to have them as efficient as possible in the lower frequencies. I am thinking of a sandwich construction with something like:
> 
> 2" fiberglass -> Vinyl barrier -> 2" fiberglass.
> 
> If I understand the theory correctly, the middle layer should improve the low frequency absorption.
> Now my question is, how is it determined what density to choose for the vinyl barrier? The site I am looking at sells 6kg/m2, 7.5kg/,2 and 15kg/m2. I guess the higher weight the lower frequency, but the weight should ensure a "linear" absorbtion coefficient for the whole system.
> 
> I am also making the same construction but with a vinyl barrier placed on the face of the panel as well to be used when only LF-absorption is wanted.
> 
> Inputs are appreciated!


Here is a graph giving a comparison of the different approaches. Use it as instructive rather than definitive, as the Q is certainly wrong for the limp mass. I believe the formula doesn't properly account for damping of the limp mass or of how a compound panel behaves. It's absorption coefficient estimates are also a bit low below 500hz for a velocity absorber as compared to what we seem to see with actual tested panels. 









Low Dense is the panel with a 6kg/m2 vinly limp massed sandwiched between two OC703 panels (I used that panels low resistivity for the estimate). The green High Density is with the highest density vinyl, 15 kg.m2. Red is a straight 4" panel and Yellow is a straight tuned trap model (Limp mass membrane over 4" of OC703. Ignore the big peak and dip, that isn't what it would really look like. The center of the peak is probably close to right and the center of the dip is probably close to right, but the shape will be far flatter than what you see here. If someone from GIK or another acoustics company that does real testing of tuned traps is around they may be able to give better insight as to why the mathematical model gives these goofy results. I have testing gear to test things like the resonance of these traps, but I don't know how to measure absorption in situ to study this concept, so I've only been able to confirm that the resonance matches closely for the membrane. 

If you are planning to put a heavy vinyl membrane in your trap, I'd take some measurements first and be certain the center frequency is going to be targeted in a good place. If you aren't sure or there isn't a real issue like that, you may want to go with a less dense membrane like 10 mil PVC. I'm having trouble confirming this but I believe the density of 10 mil PVC sheating is around 1-1.5 kg/m2. Doing that improves the absorption around the 150-200hz range rather than down at 50hz.

I hope this helps (and is right, like I said, I can't test this).
http://www.acousticmodelling.com/multi.php


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## Mpoes12

dgkula said:


> Hi,
> 
> I'm finally building my first small dedicated room as part of a post-pipe-burst basement remodel. The room is 12 x 14 with 7.5' ceilings. I need to orient the room with the projector/screen along the 12' length owing to requirements to have a door to a mechanical area. I will have 4 seats and a 92 inch screen (accommodating for another door on the front wall). Not ideal given the limited space and access requirements but I will be moving from a mixed use space with windows to a dedicated space with no windows and openings.
> 
> I have wired the room for 7.2.9 with in-walls for SL, SR, RL, RR and 4 Atmos speakers in the ceiling. My L/C/R/SW will be cabinets placed around the screen; I don't have room for a false wall and so am not doing an AT screen with false wall. I have a regular Elite fixed screen from my prior multi-use space. I plan to run dual subs to balance room modes. The walls are up and painted dark blue with a black solid ceiling (i.e. sheetrock not drop). The projector is ceiling mounted with 10.5' throw.
> 
> My question is about acoustic treatments. I have tried to read as much as possible but this thread is really hard to get through. Here are my questions:
> 
> 1. Since I don't have an AT screen, is there any point in treating the front wall? Presently I am not planning to treat the front wall. Most posters do 1" linacoustic but that seems to go with AT screens.
> 
> 2. For side walls I am torn between 1" linacoustic to 48" height versus four 3" 2 x 4 acoustic panels on each side wall (for a total of 8 panels). Cost is close - with the raw materials from Fabricmate coming in at $200 more than eight completed GIK 3" panels. Other than the aesthetics, is there any reason to go one way over the other? The panels are thicker and would provide 70% of the surface area coverage of the Linacoustic so I'm not sure what would be "better." I need to determine is aesthetics is the only basis for making this decision or if there is another factor to consider.
> 
> 3. Should I do anything with the rear wall? Many threads discuss diffusion, but my seats are 1" from rear wall which seems too close for diffusion. Some threads talk about not treating the rear wall to have reflections to minimize localization of surrounds. I haven't come to a conclusion yet and would appreciate some guidance.
> 
> 4. Since I will be running dual subs, is it fair to assume that with DSP/Audyssey will minimize the need for bass trapping?
> 
> Thanks very much! Should be up and running in the next 90 days and I will post pics?
> 
> David


1) It is good to treat the front wall for SBIR. However 1" won't have any impact on that. The 1" is used because Dennis Erksine has been suggesting two layers of it with a plastic layer in-between. He does this because he finds 2" tends to over-absorb in the 200-500hz range (if I recall his old post on this). I've found he is right and have a measurement of my sparsely treated room that is consistent with his finding, too much absorption in that range. This recommendation is to absorb sound that radiates behind the speaker. as well as any sound that is reflecting off other surfaces onto that back wall and toward the listener. These are mostly later reflections but still bad. 
2)1" is going to only absorb down to around 500hz or so. It won't provide a lot of absorption below that. In a later point you make a false assumption that leads to this. You want 4" panels here, not 1". You also don't need to treat the entire wall necessary and that decision should be dictated by your rooms RT60 response. Most small rooms that are nearly completely untreated still have RT60 values of like .3-.4ms, which is low enough that if you start covering all the surfaces with 1" absorption, would be too much. It would likely drop below .2. I would 2x4 panels, but you may consider two of these for a 4x4 area at 4" thick. 
3) You should not use diffusion if you are sitting 1" from the rear wall. You want to make the wall disappear in this case, you want absorption and lots of it. you are so close to the rear wall you won't have room for thick, but I would still go with 2" on the entire area around your head, including the side walls there. It will make the room appear larger.
4) While it is true that multiple subs and Audyssey can reduce the problems, it is not true that you don't need bass traps. You can reduce the modal ringing somewhat by reducing the modal peaks, but you can't reduce the overall decay of the bass in the room. Most rooms have far too little LF absorption. You should think about bass traps on top of the rest of this. Also remember that 2 subs doesn't automatically equal improved LF response. You have to place them precisely. You can place them in the 1/4 points of the front wall, which is symmetric and possibly between your mains, but...while that might cancel the side to side modes, it might not and it very well may not do much good at your listening position. There is a power point floating around that talks about this, but my experience is the same, this isn't a great location. There really needs to be either two subs placed in very different parts of the room (front and back for example) or really, 3-4 at key points. I've also found that Geddes approach netted smoother bass than Welti's, that using non-symmetric locations seems to work better. 

You don't mention this, but consider treating the ceiling. It helps make the ceiling appear to disappear too.


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## amit916

Hi all...

My theatre room currently sits with columns/riser/stage/soffits built and ready to paint. I divided my project into parts and the last part, (since it's a very deep subject) is acoustical treatments.

I want to get my room setup, measure, then go forward with treatments. However, life doesn't always go as according to plan. We have a lot of parties coming in the next month or so and everyone is going to see the theatre if I want it to be seen or not (really not my choice)

So the question is, can I put frames covered with fabric between my columns on the walls so it looks finished. That way it looks presentable? When the time comes I could remove them, put up acoustical treatment behind them and then put the frame back up again?

I feel like there's nothing too outlandish about that. BUT, that's why I figured I'd ask in this thread. (PS, I found most people just ask about the screen then the subs)


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## HopefulFred

amit916 said:


> So the question is, can I put frames covered with fabric between my columns on the walls so it looks finished. That way it looks presentable? When the time comes I could remove them, put up acoustical treatment behind them and then put the frame back up again?


Yep. That's a fine idea.

When you build the frames, you have the age-old question of how big (deep) to make them. The deeper the better; I'd suggest 4 or 6 inches.


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## Mpoes12

Treating an entire wall with 4"-6" material would potentially be way too much absorption. Dennis erksine seems to like 2 layers of 1" linacoustic separated with plastic sheeting to minimize excessive absorption in the midbass region of 500hz. If you do cover an entire wall you want to restrict mid and high frequency absorption to avoid drying out the room. The goal isn't the least reflections possible or lowest RT60 but rather minimized interference and a flat RT60 at around .2 to .3ms. Most small spaces will be close to that if they have carpeted floors down to 200hz or so. Most rooms need mostly Lf absorption without adding mid/high absorption. That's why you want to use broadband selectively and range limited broadly. 

See my RT60 in a room with carpet, 2" on the wall and sides around the front speakers, and 20 2'by2' 2" thick panels laying on the floor. 











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## amit916

I've seen the Erskine group specify 2 inches or favor it at least in favor of 4 where as others have preferred 4. I think setting myself for 2 or 3, either way won't be wrong. I'm not going to be able to follow an acoustic plan since it's out of my budget but if 2" is fine for Erskine Group, than who am I to complain.

I'm going to make sure it doesn't feel took cramped losing 8 inches of width, because 4 inches is what I'm leaning towards right now. So 4 inch frames. (Well 3.5 since 2x4s....)


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## Mpoes12

4" will extend absorption lower but not absorb any more sound. I suggest taking measurements before treating and have a plan for how to limit the absorption more down low if needed. 

I believe Erksine likes two 1" layers with a layer of plastic sheeting. The argument is it extends Lf absorption while limiting midbass absorption. Look at my RT60 as evidence of that trend. In my case the excess absorption is 200hz. 

I think it makes sense to use 4" of absorption at key early reflections points on the sidewalls and ceiling. The rest of the walls don't benefit from that much absorption, it just dries the room out. You can certainly try it. Fixing it can be as simple as coverkng sections in the top and bottom third with FRK. You could also add wood slats or scatter plates to fix it. 


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## Mpoes12

Oops I should say that front and rear walls DO benefit from a lot of absorption. I see arguments for only Lf absorption on the rear wall and broadband on the entire front wall (as already discussed). 


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## amit916

Mpoes12 said:


> 4" will extend absorption lower but not absorb any more sound. I suggest taking measurements before treating and have a plan for how to limit the absorption more down low if needed.
> 
> I believe Erksine likes two 1" layers with a layer of plastic sheeting. The argument is it extends Lf absorption while limiting midbass absorption. Look at my RT60 as evidence of that trend. In my case the excess absorption is 200hz.
> 
> I think it makes sense to use 4" of absorption at key early reflections points on the sidewalls and ceiling. The rest of the walls don't benefit from that much absorption, it just dries the room out. You can certainly try it. Fixing it can be as simple as coverkng sections in the top and bottom third with FRK. You could also add wood slats or scatter plates to fix it.
> 
> 
> Sent from my iPhone using Tapatalk


Definitely, that's the plan right now. Will address the treatments and measure after putting the frames up. Getting a lot of outside pressure to make it look presentable so I'll be making the fabric frames and the putting treatment behind them after measurement. It's somewhat backwards but sometimes those are the cards your dealt.


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## Mpoes12

You can also consider looking for more attractive treatments If you don't want fabric walls everywhere. 

The Gik Alpha line for example. 


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## ftwilson

*Can I use Ultimate Acoustics products for my theater?*

Hello all,

Apologies if there are details on this in other threads; if so, please point me at those and I won't bother folks any more.

I've refinished half of my basement to serve principally as a theater. I've got a 7.x Athena speaker set with an Outlaw LFM-1 Plus sub, driven by a (new) Onkyo TX SR 757. The theater is 22ft x 13ft x 6.5ft. It's drywall on the sides and tops, with carpet on the bottom. A Panasonic AE4000U provides the video.

Right now, there are no additional acoustic treatments. I'd been looking at pages that described DIY methods, but then I came across some commercial treatments at a newly opened Guitar Center, that weren't as expensive as I'd thought they'd be. They're part of the "Ultimate Acoustics" line of products, at www-dot-ultimatesupport-dot-com/products/ultimate-acoustics.html

I know I need to identify the ideal reflection points based on my seating position and speaker locations. But, I can't tell: are these products appropriate for treating my home theater, and which among them would be best suited for attaching to my walls? There's "wedge style" and "bevel style"; I can't tell if there's a difference for my purposes and which would be best.

I welcome all insights and opinions, thanks!

Todd


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## Mpoes12

I wouldn't buy those myself. The products are made of foam, they lack solid test data, and would likely not perform well. There are some foam products made or high quality acoustic foam that perform very well but I don't feel confident those products meet that criteria. 

Is your concern that you don't want to diy? Do you have a budget?


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## ftwilson

Mpoes12 said:


> I wouldn't buy those myself. The products are made of foam, they lack solid test data, and would likely not perform well. There are some foam products made or high quality acoustic foam that perform very well but I don't feel confident those products meet that criteria.
> 
> Is your concern that you don't want to diy? Do you have a budget?
> 
> 
> Sent from my iPhone using Tapatalk


Hello,

Thanks for your reply. I'm not concerned about DIY (the theater itself was DIY!), but I'd mostly been staying away from retail products because they seemed so expensive. So, seeing these at (what seemed to be) an affordable price launched the question.

I've seen the threads on DIY at acousticsfreq-dot-com and could pull those off. Would welcome alternative suggestions, but I'm sure there are a ton in the preceding entries.

Thanks!

Todd


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## Mpoes12

There are lots of ways to do acoustics diy. The absolute cheapest method is inexpensive light weight burlap over rigid roxul mounted with impaling clips and adhesive. There is no frame. To do those right it is best to stiffen the edge with epoxy. 

A simple frame with roxul AFB tends to be the next best thing. Frame have been made of MDF, plywood, solid wood, drywall edging, you name it. An open frame has advantages because exposingnthr sides increases the surface area quite a bit. 

Measurements are important because typically the goal isn't tons of absorption. Most rooms have low RT60 times to begin with but with most of that concentrated up high. Carpet absorbs a lot of sound but only at higher frequencies. Adding 4" or 6" panels over a very large area can cause too much absorption in the lower midrange upper midbass range, which often isn't needed. As a result range limiting the panels and carefully placing them becomes critical. Thick absorption at key early reflections points make sense. Thick on the wall behind the speakers doesnt make sense unless it's range limited. 

I'll be taking more measurements and sharing the results of my room as I install Incrementally more treatments trying to achieve the RT60 curve I desire and address the various acoustic problems I have. 


Sent from my iPhone using Tapatalk


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## robc1976

I love my GIK acoustics panels.


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## ereed

robc1976 said:


> I love my GIK acoustics panels.


Me too!


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## Blackdevil77

Quick question regarding my "oh so annoying" bass suck out problem. During ARC calibration and measurements, I have a SEVERE dip around 100 hz or so (about 30 db) from my front left and right speakers. I can't play much with the positioning, the only thing I could do was move them closer to the back wall, I have no more room to pull them out further or in from the side walls or else they'll be in front of the screen. When I put them up against the wall, the dip moves up to about 200 hz, but is just as severe. I bought GIK bass traps and put them in the front corners of my room from floor to ceiling, and it made ZERO difference in this drop out. It's so bad, ARC sets the crossovers for the front left and right speakers at 250 Hz, and I have JBL M2's. What's gives? What else can I do?


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## HopefulFred

Blackdevil77 said:


> What's gives? What else can I do?


I'd say the reflection from the front wall is the culprit (as evidenced by the shift in frequency when you relocated the speakers). My first thought was that you try the traps directly behind the speakers. Using bass traps in corners is effective because it addresses most or all of the modal resonances. You're not dealing with a modal resonance; it's SBIR.

You might also consider adjusting your bass management manually. Sometimes, the software can't balance trade-offs very well; you can probably make better compromises (if there needs to be one) using your own good judgement.


----------



## Blackdevil77

HopefulFred said:


> I'd say the reflection from the front wall is the culprit (as evidenced by the shift in frequency when you relocated the speakers). My first thought was that you try the traps directly behind the speakers. Using bass traps in corners is effective because it addresses most or all of the modal resonances. You're not dealing with a modal resonance; it's SBIR.
> 
> You might also consider adjusting your bass management manually. Sometimes, the software can't balance trade-offs very well; you can probably make better compromises (if there needs to be one) using your own good judgement.


That's what I had to do (bass management manually) which is a temporary fix, I think. For one speaker, that may be a challenge, there isn't much room behind the right front speaker, it's pretty much right up against the side of the screen.


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## kgveteran

ereed said:


> Me too!


 There are some among us who feel first reflection panels are 100% wrong, i believe they are very benificial.


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## ereed

kgveteran said:


> There are some among us who feel first reflection panels are 100% wrong, i believe they are very benificial.


Those people just have no idea how room treatment works or the point of first reflection points.

There is a reason recording studios and best home theaters use them.....no wonder they sound much better than your "average joe's" room!


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## VideoGrabber

ereed said:


> Those people just have no idea how room treatment works or the point of first reflection points.


Yeah, you're totally right, of course. People like Floyd Toole haven't got a clue.


----------



## JonasHansen

kgveteran said:


> There are some among us who feel first reflection panels are 100% wrong, i believe they are very benificial.


Do you believe that the correct approach is to always treat first reflection points with thick absorbing panels? 

I don't think anyone is saying that it is 100% wrong to treat first reflections... But some people are saying, that it all depends on the speakers and the distances between speaker, wall and listener. And this is, in my mind, a 100% correct approach.

EDIT: And the question is not only "to treat it or not" but HOW to treat it. Absorbtion, reflection and diffusion are the tools (or a mixture).


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## FrankTR

*Confussed*

I have scanned most of the post regarding front wall acoustic and not sure what is the latest thoughts. My room is about 20 by 14. I plan to build a screen false wall about 2 feet from the front wall. The front wall is an outside wall sheet rock with R13 insulation between the outside wall. I am on a slab with carpet. What do I put on the front wall and the side walls behind the screen?


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## HopefulFred

FrankTR said:


> What do I put on the front wall and the side walls behind the screen?


Your room is very similar to mine, and I would suggest that you do the same thing that I did: line all those surfaces with two layers of duct liner, separated by a layer of heavy plastic (I used 6 mil). This seems to be the standard, when a baffle wall is not used.


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## FrankTR

HopefulFred said:


> Your room is very similar to mine, and I would suggest that you do the same thing that I did: line all those surfaces with two layers of duct liner, separated by a layer of heavy plastic (I used 6 mil). This seems to be the standard, when a baffle wall is not used.



is this acceptable rather than duct liner which i don't seam to be able to find.

Expanded Polystyrene Foam Board Insulation


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## HopefulFred

FrankTR said:


> is this acceptable rather than duct liner which i don't seam to be able to find.
> 
> Expanded Polystyrene Foam Board Insulation


I'm afraid not. Expanded polystyrene is a closed-cell foam. Open-cell foam gets you into the right realm of materials, but in most cases a fiber is better. The material must have open but convoluted pathways for air to move through. It's the partial restriction of air movement that diminishes the sound wave propagation and ultimately the pressure level.

Something simple like cotton batting would be somewhat effective, but you need to be careful about flammability. Somewhere near you is an insulation distributor who will sell to the public. A roll of duct liner is pretty pricey, but very useful. Sometimes leftovers come up for sale in the classified section here.


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## FrankTR

HopefulFred said:


> I'm afraid not. Expanded polystyrene is a closed-cell foam. Open-cell foam gets you into the right realm of materials, but in most cases a fiber is better. The material must have open but convoluted pathways for air to move through. It's the partial restriction of air movement that diminishes the sound wave propagation and ultimately the pressure level.
> 
> Something simple like cotton batting would be somewhat effective, but you need to be careful about flammability. Somewhere near you is an insulation distributor who will sell to the public. A roll of duct liner is pretty pricey, but very useful. Sometimes leftovers come up for sale in the classified section here.


Why not just fiberglass wall insulation covered by plastic


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## HopefulFred

FrankTR said:


> Why not just fiberglass wall insulation covered by plastic


Generally, people are concerned about glass fibers floating in the air. Duct liner has a bonded surface and is designed to be exposed to open circulating air. Also, I think duct liner has slightly better efficiency due to it's higher density. Check bobgolds


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## t.stone13

I am pretty sure this is the right place to post this. If not feel free to shame and delete my post. 

I have fallen into some ‘speaker fund money’ for some mid/high treatments of my extremely reflective room. It was my plan to DIY traps and I was hoping for some advice. My primary use of the system is music (HTPC/PS4/Blu-ray Player all don’t get used near as much as my Dragonfly). Rough sketch and photos of the room are attached. Please excuse the mess – we are still moving in. Also ignore the window coverings – it’s a rental.

FYI, the ceilings are 8 ft. If it’s important to wait, my dad has a good REW setup that he will be bringing over sometime late summer. The room needs to be treated as its highly reflective (right channel Audyssey pings echo like crazy off the wall behind and in front of the speaker). The room’s bass is a mess with many obvious modes and nulls from both the mains and sub no matter what placement I use for either. However, I don’t have the money for bass treatments currently. 

My Gear
---------------
Mains: Tannoy Revolution XT 6F
Center: Polk CSi3
Sides: ADS L400
Sub: SVS PC32-25 with plate amp in external configuration due to air leakage
AVR: Marantz SR5010
Main Amp: Adcom GFA-535


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## subacabra

Good afternoon and happy 4th of July everyone! 
Decided to post here because I am going to be adding some Ats acoustic panels in my living room setup. I've done some reading up on acoustic treatments and feel I have a decent grasp of placement techniques etc but just wanted to see if anyone could add any tips or suggestions. 
I did the mirror trick for first and second reflections, and also for a panel on my ceiling. I've attached some pictures because the one side of my living room opens to my little bar, and I'm not sure how to approach that. 
I have three 24x48x2 panels, two 24x36x2 and two 24x24.
I know I'm going to put two of the bigger ones on the left wall at first and second reflections. 
A medium one on the opposite rear side wall by right surround, and a small one on the left rear wall by left rear surround. These were decided on by the mirror trick.
Also, one medium panel on ceiling for center channel first reflection. 
It's definitely going to be a little trial and error. The room is somewhat oddly shaped.
Equipment list
Denon x6200w
Outlaw 5000
PSA Mt-110's and 110c
Volt 6 front heights/surrounds
Def Tech Pm1000's rear surrounds
PSA v1500 and 15v front left corner and opposite rear right corner.
Coffee table is against tv stand so my little guy can't fiddle with equipment. I move it for movies and room correction.


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## Roger Dressler

Your plan sounds good to me. If the room is exhibiting general liveness, the panels will help damp that down nicely without much precision in placement. The ceiling will be a good location as already planned. 



subacabra said:


> one side of my living room opens to my little bar, and I'm not sure how to approach that.


A large opening like that might not be a problem. The sound coming back from there will be delayed and reduced, so should be pretty benign, as compared with the reflections off the glass covered posters (I'm assuming they are under glass?) 



> A medium one on the opposite rear side wall by right surround, and a small one on the left rear wall by left rear surround. These were decided on by the mirror trick.


Your main seat is under the PJ, right? The left side wall is an easy place to test reflection vs. absorption. The Right Rear Surround speaker is aiming there, so it will have a strong reflection into your left ear.


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## subacabra

Roger Dressler said:


> Your plan sounds good to me. If the room is exhibiting general liveness, the panels will help damp that down nicely without much precision in placement. The ceiling will be a good location as already planned.
> 
> A large opening like that might not be a problem. The sound coming back from there will be delayed and reduced, so should be pretty benign, as compared with the reflections off the glass covered posters (I'm assuming they are under glass?)
> 
> Your main seat is under the PJ, right? The left side wall is an easy place to test reflection vs. absorption. The Right Rear Surround speaker is aiming there, so it will have a strong reflection into your left ear.


Thank you so much for your input, I really appreciate it! Would you also be concerned about the wall by left surround? The one with the little pictures on it. Sitting in my mlp(little couch under pj) I can't see any reflection points due to seating position, but I would assume the left surround and left front height are reflecting off there.
Going to mount panels tomorrow and report back with findings. 
Thanks again!


----------



## Roger Dressler

subacabra said:


> Would you also be concerned about the wall by left surround? The one with the little pictures on it. Sitting in my mlp(little couch under pj) I can't see any reflection points due to seating position, but I would assume the left surround and left front height are reflecting off there.


I was under the impression you had already planned to attach panels on that wall to capture first reflections. No? Maybe a plan diagram of the room would help if you want to delve deeper.

My biggest concern is that the Ls speaker appears to be somewhat blocked by the wall with the 4 small pictures on it. (Round the corner to the left of the MLP.) Might need to consider either moving the sofa or the Ls speaker forward. Or it might just be the camera playing tricks.


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## subacabra

Roger Dressler said:


> I was under the impression you had already planned to attach panels on that wall to capture first reflections. No? Maybe a plan diagram of the room would help if you want to delve deeper.
> 
> My biggest concern is that the Ls speaker appears to be somewhat blocked by the wall with the 4 small pictures on it. (Round the corner to the left of the MLP.) Might need to consider either moving the sofa or the Ls speaker forward. Or it might just be the camera playing tricks.


If I sit all the way back, my ears are definitely not getting much line of sight from the ls. I usually sit a little forward so it's better. I could scoot the couch forward a few inches, but where it is my bass is awesome. 
That corner is pesky and that was my only location really for the ls, because I didn't want them too far forward.
But yes, I do plan on a panel there as well, because in my secondary seating position(middle big couch) I can easily see reflection points from both ls and left front height.
Sorry for rambling on lol
Appreciate the help


----------



## ereed

subacabra said:


> Good afternoon and happy 4th of July everyone!
> Decided to post here because I am going to be adding some Ats acoustic panels in my living room setup. I've done some reading up on acoustic treatments and feel I have a decent grasp of placement techniques etc but just wanted to see if anyone could add any tips or suggestions.
> I did the mirror trick for first and second reflections, and also for a panel on my ceiling. I've attached some pictures because the one side of my living room opens to my little bar, and I'm not sure how to approach that.
> I have three 24x48x2 panels, two 24x36x2 and two 24x24.
> I know I'm going to put two of the bigger ones on the left wall at first and second reflections.
> A medium one on the opposite rear side wall by right surround, and a small one on the left rear wall by left rear surround. These were decided on by the mirror trick.
> Also, one medium panel on ceiling for center channel first reflection.
> It's definitely going to be a little trial and error. The room is somewhat oddly shaped.
> Equipment list
> Denon x6200w
> Outlaw 5000
> PSA Mt-110's and 110c
> Volt 6 front heights/surrounds
> Def Tech Pm1000's rear surrounds
> PSA v1500 and 15v front left corner and opposite rear right corner.
> Coffee table is against tv stand so my little guy can't fiddle with equipment. I move it for movies and room correction.


You need to slide the love seat forward where back of the love seat is where rear/side wall is. There is more content coming from side speakers vs rear speakers and you are not within sight of it. Bass traps in the corners will help as well if you have room for those.


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## subacabra

ereed said:


> You need to slide the love seat forward where back of the love seat is where rear/side wall is. There is more content coming from side speakers vs rear speakers and you are not within sight of it. Bass traps in the corners will help as well if you have room for those.


I really want to, but my living room is small as it is and it'll make it appear even smaller. Also the closer I get to middle of room, there is a decent bass null. I could probably swing a 4-6" move forward though.
I may move some things around though.
Definitely realize I'm missing a lot from that left surround unless I'm leaning forward lol
Can't wait to sell my condo and get a house with a dedicated room!


----------



## ereed

subacabra said:


> I really want to, but my living room is small as it is and it'll make it appear even smaller. Also the closer I get to middle of room, there is a decent bass null. I could probably swing a 4-6" move forward though.
> I may move some things around though.
> Definitely realize I'm missing a lot from that left surround unless I'm leaning forward lol
> Can't wait to sell my condo and get a house with a dedicated room!


Move that rear sub (where Dredd picture is) and use that as your end table instead.....no more nulls. LOL And not only you get more impact from bass, you get better overall sound from surround speakers.....AND you get little closer to tv for more immersive view. I find all 3 of those FREE upgrades.  Just try it and experiment.


----------



## subacabra

ereed said:


> Move that rear sub (where Dredd picture is) and use that as your end table instead.....no more nulls. LOL And not only you get more impact from bass, you get better overall sound from surround speakers.....AND you get little closer to tv for more immersive view. I find all 3 of those FREE upgrades.  Just try it and experiment.


I've considered this too! Just have to convince my 3 year old not to fiddle with the sub controls  
I may just do that!


----------



## subacabra

Got a few panels mounted last night after work. So far so good.
Took into account possibly moving mlp couch forward some. 
Will try to finish up the rest tonight, run room correction etc.
The ceiling one should be a hoot.


----------



## ereed

Looking good with the panels....should be less reflections and sound should be more clear or how audiophiles puts it, "better imaging".


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## kgveteran

Inregards to first reflection points, you wouldnt mount speakers there would you, there is little difference between a full range reflection or a speaker mounted there, with a nice 10ms delay......

If you dont think it has broad bandwidth, then why are Atmos modules so popular, they reflect off the ceiling, only difference is Atmos modules are not competing with itself, it reflects off the ceiling and gives you an illusion the speaker is up there on the ceiling. I think there are more modules than dedicated Atmos speakers out there, from what i read. I will be using Atmos speakers on my ceiling im sure

Regardless what anyone says, and who says it, absorbing that reflection sounds better. Better means there is no faux wide spacial smeared sound stage. Now if you like that, and you like it because you tryed absorbers, good broadband absorbers, then took them down, then so be it, at least you gave a try to an age old process.

I believe its really a matter of what you like, i hate having my center channel sound, bounce off of two side walls, one ceiling, possibly a rear wall with more than 6db or more of gain from the original sound some 5-12ms later. 

There are more than enough speakers to create a SoundStage that the original soundtrack was meant to sound like, like the room it originated in, a well controled sound environment, not a dead lifeless one, that makes no sense either. A dead room is no fun either.

I use LEDE. I have heard over treated rooms, and no treatment rooms, i would rate them in this order, LEDE, over treated, no treatment........try as many variables as you can, dont let anyone tell you one is better than the other, TRY IT ALL, and then decide for your self.


----------



## kgveteran

VideoGrabber said:


> Yeah, you're totally right, of course. People like Floyd Toole haven't got a clue.


 I doubt everyone, i question everything. All im saying is try it out and see what your ears tell you. I have never heard of anyone who took down their first reflection point absorbers in favor of a flat reflective surface, Never once.

I have heard HT owners and installers who do not use acoustic treatments Im not so shocked at the home owner due to lack of experience, but to have professional installers say that, is criminal, and they should remove Professional from their title, and just call them selves "installers", simply hooking up gear.

I've wanted to do treatments on ceilings for soundbars, and my customers say no way ! Thats different, than "acoustic treatments are not necessary", or "I dont use them"


JonasHansen said:


> Do you believe that the correct approach is to always treat first reflection points with thick absorbing panels?
> 
> I don't think anyone is saying that it is 100% wrong to treat first reflections... But some people are saying, that it all depends on the speakers and the distances between speaker, wall and listener. And this is, in my mind, a 100% correct approach.
> 
> EDIT: And the question is not only "to treat it or not" but HOW to treat it. Absorbtion, reflection and diffusion are the tools (or a mixture).


 You always have a choice, there are many options inregard to acoustically treating your room. As i stated to the other member, i have NEVER once heard of someone taking down their first reflection point absorbers in favor of a reflective flat surface.


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## nirvana_av

JonasHansen said:


> I don't think anyone is saying that it is 100% wrong to treat first reflections... But some people are saying, that it all depends on the speakers and the distances between speaker, wall and listener. And this is, in my mind, a 100% correct approach.


There are only two situations that I can think of that would not benefit from treatment at first reflections and they are well designed horns in the corners of your room or dipole/open baffle speakers. Both of these are predominantly two-channel arrangements.


----------



## kgveteran

nirvana_av said:


> There are only two situations that I can think of that would not benefit from treatment at first reflections and they are well designed horns in the corners of your room or dipole/open baffle speakers. Both of these are predominantly two-channel arrangements.


 Or......if they have installed them correctly and did not like them


----------



## ereed

t.stone13 said:


> I am pretty sure this is the right place to post this. If not feel free to shame and delete my post.
> 
> I have fallen into some ‘speaker fund money’ for some mid/high treatments of my extremely reflective room. It was my plan to DIY traps and I was hoping for some advice. My primary use of the system is music (HTPC/PS4/Blu-ray Player all don’t get used near as much as my Dragonfly). Rough sketch and photos of the room are attached. Please excuse the mess – we are still moving in. Also ignore the window coverings – it’s a rental.
> 
> FYI, the ceilings are 8 ft. If it’s important to wait, my dad has a good REW setup that he will be bringing over sometime late summer. The room needs to be treated as its highly reflective (right channel Audyssey pings echo like crazy off the wall behind and in front of the speaker). The room’s bass is a mess with many obvious modes and nulls from both the mains and sub no matter what placement I use for either. However, I don’t have the money for bass treatments currently.
> 
> My Gear
> ---------------
> Mains: Tannoy Revolution XT 6F
> Center: Polk CSi3
> Sides: ADS L400
> Sub: SVS PC32-25 with plate amp in external configuration due to air leakage
> AVR: Marantz SR5010
> Main Amp: Adcom GFA-535


Nice equipment. You definitely need treatments on your walls....its very reflective like you said cause bare walls will reflect sound back at you. Start with few panels to treat your first reflection points on side walls and also your rear wall. You can do just few panels and add more as you go.


----------



## t.stone13

ereed said:


> Nice equipment. You definitely need treatments on your walls....its very reflective like you said cause bare walls will reflect sound back at you. Start with few panels to treat your first reflection points on side walls and also your rear wall. You can do just few panels and add more as you go.


Appreciate the compliment.  Lots of upgrades to come in the next few years (treatments, amp, sub, center channel, etc) but I am finally feeling that I have a system I can begin to call 'high end' . How thick would you recommend I make those first reflection and rear wall treatments? For the rear wall - assume you mean the wall with the bookshelf - should I try to treat the whole wall or use a mirror to find the best location(s)?

Thanks!


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## subacabra

All panels mounted and room correction ran. Very happy with the results!


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## ereed

t.stone13 said:


> Appreciate the compliment.  Lots of upgrades to come in the next few years (treatments, amp, sub, center channel, etc) but I am finally feeling that I have a system I can begin to call 'high end' . How thick would you recommend I make those first reflection and rear wall treatments? For the rear wall - assume you mean the wall with the bookshelf - should I try to treat the whole wall or use a mirror to find the best location(s)?
> 
> Thanks!


You only want to do the mirror trick for first reflection points and then go from there. If you treat the whole wall you may end up making it dead sounding. Just do a few at first and see how you like it.


----------



## Augmont

I would like to get started on my materials list for DIY room treatments for a new HT room that is currently in the beginning stages of the build. Lots of good stuff on this thread but not sure what i need and materials to go with it. 

My plan is to line the front wall behind the false wall with _________ (help me fill in the blank) and build a false wall to hide the speakers. The false wall will be covered AT fabric of course. The room is square so I know I will need some bass traps in the corners and I know I will need to treat the first reflection point. on the back wall, how do you determine location and size of treatment. Same question for the ceiling.

I still haven't determined if I plan to cover in fabric the first 6ft of the room with velvet for the screen reflection.

I like building things so it's why I prefer to go the DIY route.....plus to lower my cost and customize to my desire.

Anyhow, I appreciate the opinions for all you experts cause I know my limitations and smart enough to ask more knowledge people than me. Help me learn in the process.


----------



## kgveteran

Augmont said:


> I would like to get started on my materials list for DIY room treatments for a new HT room that is currently in the beginning stages of the build. Lots of good stuff on this thread but not sure what i need and materials to go with it.
> 
> My plan is to line the front wall behind the false wall with _________ (help me fill in the blank) and build a false wall to hide the speakers. The false wall will be covered AT fabric of course. The room is square so I know I will need some bass traps in the corners and I know I will need to treat the first reflection point. on the back wall, how do you determine location and size of treatment. Same question for the ceiling.
> 
> I still haven't determined if I plan to cover in fabric the first 6ft of the room with velvet for the screen reflection.
> 
> I like building things so it's why I prefer to go the DIY route.....plus to lower my cost and customize to my desire.
> 
> Anyhow, I appreciate the opinions for all you experts cause I know my limitations and smart enough to ask more knowledge people than me. Help me learn in the process.


 The area behind your screen can use some OC703 board, wrapped in cheap burlap just to contain the dust, or what ever material fabric is cheap.

Prioritize all your flat surfaces and corners, each will require the right treatment to achieve the result you are looking for.

Example, i have two flat surface area's that have a slap echo/flutter echo. Its not i high priority, like a first reflecton point, its well out of the way, so some wood diffusers will break up the parallel surfaces and reduce any colour produced by erant sounds.

You will hear opinions also that first reflection absorbers create a blackhole effect that is very unatural. 100% true.......if you fail to complete proper treatment of the rest of the room. If you continue to address all these surfaces that ADD reflections, and their own signature sound, you have removed the room and now hear the music/movies.

But, dont be a follower, dont listen to me or anyone else and just DO. Get involved, add and subtract as you see fit, listen listen and listen some more. The worst advice is to do it cause i said so.


----------



## subacabra

So I got a chance yesterday to really crank the system and test out these panels. Played scenes from Need for Speed, Oblivion, MMFR, World War Z, Pulse, Life, Incredible Hulk and couple others.
It sounds awesome but.. I think I may have over treated the left wall. Maybe I'm just not used to it without all the reflections but it just seemed a little off to me. 
I may try removing the circled panel which was for the secondary reflection of front right and center and see if it sounds a little better. 
I also may try a smaller panel there. 
Guess we'll see!


----------



## Roger Dressler

Augmont said:


> The room is square so I know I will need some bass traps in the corners


Maybe not. But that can be decided later, after some measurements are done in the actual space. 

I'd suggest planning for 4 subwoofers, in the 4 corners if possible, but not required. Just getting a second pair in the rear will work wonders for taming bass issues. Being able to slide the row of seats fore/aft a bit will also allow some fine tuning (dodging of the room modes). No need to install 4 subs on day 1, but after you start using the room, you can decide on that step. It will be easier if you have power and audio lines run already.


----------



## kgveteran

subacabra said:


> So I got a chance yesterday to really crank the system and test out these panels. Played scenes from Need for Speed, Oblivion, MMFR, World War Z, Pulse, Life, Incredible Hulk and couple others.
> It sounds awesome but.. I think I may have over treated the left wall. Maybe I'm just not used to it without all the reflections but it just seemed a little off to me.
> I may try removing the circled panel which was for the secondary reflection of front right and center and see if it sounds a little better.
> I also may try a smaller panel there.
> Guess we'll see!


 Only an ETC graph could show you if the panels are absorbing the whole reflection, broadband absorbers are what you are looking for, two inch thick absorbers are good for the highs, but to absorb lower frequecies of the reflection it needs to be thicker.

What do you measure with ? The object is to reduce your reflections below 10ms..... It does take some time to get use to RFZ's


----------



## kgveteran

Roger Dressler said:


> Maybe not. But that can be decided later, after some measurements are done in the actual space.
> 
> I'd suggest planning for 4 subwoofers, in the 4 corners if possible, but not required. Just getting a second pair in the rear will work wonders for taming bass issues. Being able to slide the row of seats fore/aft a bit will also allow some fine tuning (dodging of the room modes). No need to install 4 subs on day 1, but after you start using the room, you can decide on that step. It will be easier if you have power and audio lines run already.



I run (4) 15" subs, i use to just spread them across the front of my room below the screen. Evenly spaced across the 13' width of the room. I was rearanging my room and slid the two in the center to either side, so two to the left and two to the right. Then pulled them away from the front wall a bit, and my nulls were gone !!!!!! I had two subs in the middle of the room which was disasterous, now with two to one side, two to the left, i no longer use my MiniDSP to EQ!!!!!


----------



## Augmont

kgveteran said:


> The area behind your screen can use some OC703 board, wrapped in cheap burlap just to contain the dust, or what ever material fabric is cheap.
> 
> Prioritize all your flat surfaces and corners, each will require the right treatment to achieve the result you are looking for.
> 
> Example, i have two flat surface area's that have a slap echo/flutter echo. Its not i high priority, like a first reflecton point, its well out of the way, so some wood diffusers will break up the parallel surfaces and reduce any colour produced by erant sounds.
> 
> You will hear opinions also that first reflection absorbers create a blackhole effect that is very unatural. 100% true.......if you fail to complete proper treatment of the rest of the room. If you continue to address all these surfaces that ADD reflections, and their own signature sound, you have removed the room and now hear the music/movies.
> 
> But, dont be a follower, dont listen to me or anyone else and just DO. Get involved, add and subtract as you see fit, listen listen and listen some more. The worst advice is to do it cause i said so.


Thanks.....


----------



## Augmont

Roger Dressler said:


> Maybe not. But that can be decided later, after some measurements are done in the actual space.
> 
> I'd suggest planning for 4 subwoofers, in the 4 corners if possible, but not required. Just getting a second pair in the rear will work wonders for taming bass issues. Being able to slide the row of seats fore/aft a bit will also allow some fine tuning (dodging of the room modes). No need to install 4 subs on day 1, but after you start using the room, you can decide on that step. It will be easier if you have power and audio lines run already.


I plan to start with 2 15" subs up front as a starting point, 5 ft from each corner. Preference is to keep the room at 2 subs. I may consider one towards the back. I will plan and cable the corners however so I don't have fish wire later.


----------



## kgveteran

Augmont said:


> I plan to start with 2 15" subs up front as a starting point, 5 ft from each corner. Preference is to keep the room at 2 subs. I may consider one towards the back. I will plan and cable the corners however so I don't have fish wire later.


 What do you use to measure with, i've been using OmniMic for a few years now, pretty handy tool.


----------



## Augmont

kgveteran said:


> What do you use to measure with, i've been using OmniMic for a few years now, pretty handy tool.


I have both OmniMic and REW with UMIK-1. Sadly, the REW was too complicated for my use and learning curve. I have played with OmniMic years ago but need refresher. I bought these toys years ago in anticipation for a HT room which will be a reality in the next few months. YEA FOR ME!!!!!!


----------



## HTMatrix

Just spent $1,300 today on treatments, seems insane, hope its worth it...


----------



## dnoonie

I ordered some dent and ding 2' x 4' by 4" bass traps from Acoustimac. I picked them up yesterday and the boxes seemed particularly heavy...so I weighed another same sized bass trap I got from them a few years back, non dent and ding...12 lbs, and the most recent is 21 lbs. I would guess the most recent must be filled with 8lb Rorxul. So I weighted another set of dent and ding bass traps I got from them last year at 17.5 lbs, I guessing it must be filled with 6 lb Rorxul. I'll be putting these in the back of the room which has the most bass build up right now. Some day I might get 2 more subs for the rear which should help the room response but for now this is great.

Cheers,


----------



## kgveteran

HTMatrix said:


> Just spent $1,300 today on treatments, seems insane, hope its worth it...


 DIY is a huge savings for the future, most all acoustic treatments can be duplicated ur self if you wanted to. Good luck


----------



## kgveteran

Augmont said:


> I have both OmniMic and REW with UMIK-1. Sadly, the REW was too complicated for my use and learning curve. I have played with OmniMic years ago but need refresher. I bought these toys years ago in anticipation for a HT room which will be a reality in the next few months. YEA FOR ME!!!!!!


 Yup REW is way over my head too, OmniMic works perfect for what i need.

I've used the ETC feature too, pretty comprehensive


----------



## HTMatrix

kgveteran said:


> DIY is a huge savings for the future, most all acoustic treatments can be duplicated ur self if you wanted to. Good luck


Thanks, I'll take that into consideration next time. The costs for the panels added up quicker than I thought and I just went for it. I dont think I even want to know how much it would have been if I had done it myself.


----------



## kgveteran

HTMatrix said:


> Thanks, I'll take that into consideration next time. The costs for the panels added up quicker than I thought and I just went for it. I dont think I even want to know how much it would have been if I had done it myself.


 I understand completely. If at a later date you need a hand doing some panels send out a PM


----------



## VideoGrabber

Sorry for catching up a week late, but:



kgveteran said:


> I run (4) 15" subs, i use to just spread them across the front of my room below the screen. Evenly spaced across the 13' width of the room. I was rearanging my room and slid the two in the center to either side, so two to the left and two to the right. Then pulled them away from the front wall a bit, and my nulls were gone !!!!!! *I had two subs in the middle of the room* which was disasterous [sic], now with two to one side, two to the left, i no longer use my MiniDSP to EQ!!!!!


By this, I have to assume you really meant in the middle of *the front wall*. Correct? Unless you had been sitting on them.


----------



## kgveteran

VideoGrabber said:


> Sorry for catching up a week late, but:
> 
> 
> 
> By this, I have to assume you really meant in the middle of *the front wall*. Correct? Unless you had been sitting on them.


 Correct, the two 15's were front center, two were against the side walls. I had read that bad things happen out in the middle of the room.... It got me thinking to measure them to the sides. It was amazing what that did to the response. My room is a rectangle, very simple setup, now even better, no EQ. When i do a final tweak of the bottom end i may add a little boost, but only if it really needs it. audyssey adds a nice curve with dynamic eq, probably no eq needed.


----------



## rawhit

*Corner Bass Trap Build - Add FSK paper for high freq reflection?*

My first post in this thread. Have a very specific question about bass traps.

I've taken care of the 1st, 2nd reflection points in my HT room with knauf ecose panels and now trying to correct the bass.
Built frames for corner mounted bass traps and plan to fill them up with Roxul Safe and Sound.

To avoid too much high frequency absorption, thinking of adding FSK tape to front facing side of the bass traps.

Wondering if I should I cover completely with FSK or only apply selectively in some pattern to get the best results?

Pics below

Any input appreciated!


----------



## kgveteran

rawhit said:


> My first post in this thread. Have a very specific question about bass traps.
> 
> I've taken care of the 1st, 2nd reflection points in my HT room with knauf ecose panels and now trying to correct the bass.
> Built frames for corner mounted bass traps and plan to fill them up with Roxul Safe and Sound.
> 
> To avoid too much high frequency absorption, thinking of adding FSK tape to front facing side of the bass traps.
> 
> Wondering if I should I cover completely with FSK or only apply selectively in some pattern to get the best results?
> 
> Pics below
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Any input appreciated!




Its cheap enough to cover them with a craft paper, see how that sounds, mite liven things up a bit.....


----------



## dunnar

I'm starting a basement remodel. The TV area isn't really a dedicated theater room, but I want to do whatever I can to increase sound quality as I build the walls because I'm not sure I will be able to hang acoustic panels on them after they are built (WAF). The TV area is 14' (D) x 12' (W) x 8' (H), but it's part of a large, open floor plan. The TV area is in the corner of the basement with a front wall and a left wall (no rear or right walls). What are your recommendations? Thanks in advance!


----------



## HopefulFred

dunnar said:


> The TV area is in the corner of the basement with a front wall and a left wall (no rear or right walls). What are your recommendations? Thanks in advance!


I'd say the most important thing is going to be symmetry. I'd seriously consider putting the display in the corner and setting up the seats on the diagonal. That's somewhat heretical, but to me the biggest things you can do for surround sound are: 1) put the speakers in the right place places around the seats 2) everything else...


The wall on one side and not the other throw everything off, and I bet your wife would like it a lot more.


----------



## kgveteran

Start with the ceiling, is it relecting the LCR, a mirror and a helping hand can locate that spot


----------



## jamesyates

*Help! Vaulted ceiling Atmos Theater Acoustics*

Hi Everyone,

I am buying a new house with the following room and will be using it as an Atmos theater (see picture). What acoustical issue will I most likely have to deal with in a room like this.

As A side note.

I plan on using a projector and will place a screen over the shuttered windows. As for Atmos speakers I have not figured that one out. In wall most likely will not work due to the Angle. I would like to match my KEFQ900 speakers with Atmos speaker, but it seems unlikely as I am not sure if I want to to mount the bulky bookshelf speakers to the ceiling. I do not know of any other KEF option that would work with a vaulted ceiling.


----------



## rawhit

kgveteran said:


> Its cheap enough to cover them with a craft paper, see how that sounds, mite liven things up a bit.....


Finished with the bass trap (used the FSK paper cover too).
Will take some REW measurements to see if it reduced some bass ringing.


----------



## emerson1

Moving into a house with hard wood flooring. Already have a 7x10 shag rug to use, but should I get a thick pad to go underneath it?

https://www.amazon.com/100-Felt-Rug-Pad-Protection/dp/B00H4HM3PM

Is what I am looking at. Would love to spend a lot less if possible.


----------



## kevin j

The pad can't hurt go for it.


----------



## grendelrt

Hey guys, been working on removing reflections in my room. I found I have a reflection from my FL and FR speakers (Maybe center too) on the ceiling (tried left, right, floor, and behind first haha). I have panels in the room, but I dont think I want to hang a 4" wood frame panel on the ceiling. What are my options for trying to defeat this reflection? Would diffusion work for something like this? Or maybe 2 inches rockwool 60 wrapped in fabric? Edit: More info , the room is 18x13x8, seating is about 10ft back from the front speakers. I am running atmos with 4 ceiling speakers as well. Currently there is no treatment on the ceiling, floor is carpet, left and right walls have 4" panels (will be adding more) and the rear center of the room has 3 panels side by side going up the wall toward ceiling (angled ceiling there from roof line). 

Reflection in question









Holding a panel above, in front of speaker


----------



## dnoonie

grendelrt said:


> Hey guys, been working on removing reflections in my room. I found I have a reflection from my FL and FR speakers (Maybe center too) on the ceiling (tried left, right, floor, and behind first haha). I have panels in the room,* but I dont think I want to hang a 4" wood frame panel on the ceiling.* What are my options for trying to defeat this reflection? Would diffusion work for something like this? Or maybe 2 inches rockwool 60 wrapped in fabric? Edit: More info , the room is 18x13x8, seating is about 10ft back from the front speakers. I am running atmos with 4 ceiling speakers as well. Currently there is no treatment on the ceiling, floor is carpet, left and right walls have 4" panels (will be adding more) and the rear center of the room has 3 panels side by side going up the wall toward ceiling (angled ceiling there from roof line).


What is the complication hanging a panel from the ceiling? I have an older house and have sagging ceiling drywall (it was put in with nails not screws) I've fixed some areas with screws...but for ceiling absorbers I put hooks into the truss and hung off of those since I didn't feel comfortable hanging off the ceiling drywall itself. Just a guess/idea. I use 4 hooks for a 21lb 2'x4'x4" 8lb Rorxul panel, I've had an entire panel hanging from one hook while installing no problem, trusses can handle a lot of weight as can (to a relative extent for room treatmenst) hooks, eyes and nylon ties.

Cheers,


----------



## grendelrt

dnoonie said:


> What is the complication hanging a panel from the ceiling? I have an older house and have sagging ceiling drywall (it was put in with nails not screws) I've fixed some areas with screws...but for ceiling absorbers I put hooks into the truss and hung off of those since I didn't feel comfortable hanging off the ceiling drywall itself. Just a guess/idea. I use 4 hooks for a 21lb 2'x4'x4" 8lb Rorxul panel, I've had an entire panel hanging from one hook while installing no problem, trusses can handle a lot of weight as can (to a relative extent for room treatmenst) hooks, eyes and nylon ties.
> 
> Cheers,


More of an aesthetic thing, I might be able to do a 2" panel or something, but I don't want anything really large hanging down if possible. With the ceiling speakers and projector could get complicated. Looking for other possibilities before I go down that road =) Didn't know if diffusion was one, I only have absorption right now and I know there is supposed to be a balance.


----------



## dnoonie

grendelrt said:


> More of an aesthetic thing, I might be able to do a 2" panel or something, but I don't want anything really large hanging down if possible. With the ceiling speakers and projector could get complicated. Looking for other possibilities before I go down that road =) Didn't know if diffusion was one, I only have absorption right now and I know there is supposed to be a balance.


2" absorbers with 703/705/Roxul works pretty well, I've switched to 4" for my front ceiling first reflection points but the 2" seemed to do a good job too. I have Roxul 4lb in the front and a mix of 4lb and 8lb in the back. I have 2" on the front sides with a 1" gap (first and second reflection points), because of space considerations I'm not going with 4".

The rule of thumb for diffusion positioning is a foot of distance for every inch of thickness for the diffusion otherwise you get image smearing (at least that's been my experience, someone with more knowledge might be able to fill in) so if you have the distance from the ceiling 1st reflection point to your seating position diffusion might work for you. Diffusion would tend to be thicker than absorption so I'm not sure it would be better for you or not.

Cheers,


----------



## grendelrt

dnoonie said:


> 2" absorbers with 703/705/Roxul works pretty well, I've switched to 4" for my front ceiling first reflection points but the 2" seemed to do a good job too. I have Roxul 4lb in the front and a mix of 4lb and 8lb in the back. I have 2" on the front sides with a 1" gap (first and second reflection points), because of space considerations I'm not going with 4".
> 
> The rule of thumb for diffusion positioning is a foot of distance for every inch of thickness for the diffusion otherwise you get image smearing (at least that's been my experience, someone with more knowledge might be able to fill in) so if you have the distance from the ceiling 1st reflection point to your seating position diffusion might work for you. Diffusion would tend to be thicker than absorption so I'm not sure it would be better for you or not.
> 
> Cheers,


Yeah etc graph says 4.65ft to the point on the ceiling, so that's 4.65inches at the hight point of the diffusion material? For a 2" roxul panel I wonder if I could get away without framing it, maybe use a back board and fabric, 2" seems doable at least.


----------



## dnoonie

grendelrt said:


> Yeah etc graph says 4.65ft to the point on the ceiling, so that's 4.65inches at the hight point of the diffusion material? For a 2" roxul panel I wonder if I could get away without framing it, maybe use a back board and fabric, 2" seems doable at least.


The GIK 2" panels are 3.625" thick since they have a built in plenum. The Acoustimac 2" panel is 2.25" thick with backing (I have the Acoustimac and I measured it). If you can spare slightly less than a 1/4" I'd go with a backing, it just seems like it would be easier to mount.

For flush mount to a ceiling I would choose the Acoustimac z-bar, http://www.acoustimac.com/acoustic-insulation-materials/installation-hardware, I've used these and like them, they give you a little wiggle room as apposed to the ATS z-bar, https://www.atsacoustics.com/acoustic-panel-zbars.html, which I have also used, they give you a supper snug fit, no wiggle room so it would scar any surface you use them on when you mount a panel, the advantage being that you're not going to have any rattles to deal with (I've cleaned up mounting hardware rattles by putting cloth around z-clips and z-bars). If you have a panel without a backing you could possibly use Rotofast anchors, https://www.atsacoustics.com/cat--Accessories--103.html, I've not tried them so I don't know how well they work. I'm just not sure how to do a supper clean look flush mount without a backing.

Cheers,


----------



## grendelrt

dnoonie said:


> The GIK 2" panels are 3.625" thick since they have a built in plenum. The Acoustimac 2" panel is 2.25" thick with backing (I have the Acoustimac and I measured it). If you can spare slightly less than a 1/4" I'd go with a backing, it just seems like it would be easier to mount.
> 
> For flush mount to a ceiling I would choose the Acoustimac z-bar, http://www.acoustimac.com/acoustic-insulation-materials/installation-hardware, I've used these and like them, they give you a little wiggle room as apposed to the ATS z-bar, https://www.atsacoustics.com/acoustic-panel-zbars.html, which I have also used, they give you a supper snug fit, no wiggle room so it would scar any surface you use them on when you mount a panel, the advantage being that you're not going to have any rattles to deal with (I've cleaned up mounting hardware rattles by putting cloth around z-clips and z-bars). If you have a panel without a backing you could possibly use Rotofast anchors, https://www.atsacoustics.com/cat--Accessories--103.html, I've not tried them so I don't know how well they work. I'm just not sure how to do a supper clean look flush mount without a backing.
> 
> Cheers,


 Doh I bought some 2" Roxul 60 from Acoustimac today already. Can you get those zbar equivalent locally at lowes or somewhere (if not I can order some later once I know how many panels)? I was thinking of just building a frame for the acoustic material to keep the edges looking nice. Might actually put a back board on the frame and use spray adhesive or something to help with the droop of the roxul laying on the fabric. Any ideas on that part, I know my wall panels the roxul moves around but its not much of an issue since they aren't upside down.


----------



## dnoonie

grendelrt said:


> Doh I bought some 2" Roxul 60 from Acoustimac today already. Can you get those zbar equivalent locally at lowes or somewhere (if not I can order some later once I know how many panels)? I was thinking of just building a frame for the acoustic material to keep the edges looking nice. Might actually put a back board on the frame and use spray adhesive or something to help with the droop of the roxul laying on the fabric. Any ideas on that part, I know my wall panels the roxul moves around but its not much of an issue since they aren't upside down.


If you call or email them you might be able to get them to add the z-bar to the order.

Most of my panels I've purchased from Acoustimac and they simply stretch the fabric tight enough that there's no sag and staple it in place. So when I made a set of panels (I needed a custom size) I simply stretched the fabric tight enough to eliminate sag, I used a staple gun to secure the fabric (just the standard Arrow T50, practically wore my hand out). I'm happy with the results and my projects have been spaced months apart to give my hand a rest...I still just use the T50. If you don't have a staple gun consider an electric or or air type if you have a compressor.

Attached you'll find pics of a black panel that I did myself and a red panel that Acoustimac did. Note that the fabric was cut with pinking sheers to eliminate unraveling of the fabric. The Fabric is Acoustimac DMD, in hind site I wish I'd have used Gilfords for ease of matching. 

Cheers,


----------



## grendelrt

Nice the fabric I have used in the past wasn't that strong, so maybe I'll switch that up. I was also thinking I could just put some clips on the side facing the floor to keep the material from laying on the fabric, as long as my chunks of roxul lay flat on them.


----------



## jamesyates

*Vaulted ceiling acoustics with ATMOS*

Hello All,

Just purchased a house and what is to be the media room has a very vaulted ceiling. What are the trouble spots here to deal with first? Any acoustical treatment suggestions? Will be adding ATMOS height speakers somehow and using a 7.2 surround with two subs. The screen will be about 9 feet wide and be a screen that raised from the floor like the following.

http://elitescreens.com/front/front/productdetail/product/161

Any suggestions welcome. Thank you all.


----------



## LydMekk

Exact dimensions of the space would help ^^.


----------



## jamesyates

LydMekk said:


> Exact dimensions of the space would help ^^.


I only have the floor size and do not have access to the home yet till closing. Thanks.
16x18


----------



## Witchboard

Does anybody know a local source in Oklahoma City for Roxul rockboard or Owens-Corning 703/705? None of the big box stores carry it and all the insulation guys I've looked into specialize in blown insulation rather than batting.


----------



## darrellh44

dnoonie said:


> The GIK 2" panels are 3.625" thick since they have a built in plenum. The Acoustimac 2" panel is 2.25" thick with backing (I have the Acoustimac and I measured it). If you can spare slightly less than a 1/4" I'd go with a backing, it just seems like it would be easier to mount.
> 
> *For flush mount to a ceiling I would choose the Acoustimac z-bar, http://www.acoustimac.com/acoustic-insulation-materials/installation-hardware, I've used these and like them, they give you a little wiggle room as apposed to the ATS z-bar*, https://www.atsacoustics.com/acoustic-panel-zbars.html, which I have also used, they give you a supper snug fit, no wiggle room so it would scar any surface you use them on when you mount a panel, the advantage being that you're not going to have any rattles to deal with (I've cleaned up mounting hardware rattles by putting cloth around z-clips and z-bars). If you have a panel without a backing you could possibly use Rotofast anchors, https://www.atsacoustics.com/cat--Accessories--103.html, I've not tried them so I don't know how well they work. I'm just not sure how to do a supper clean look flush mount without a backing.
> 
> Cheers,


+1 on the Z-bars. They worked great on my ceiling panels. They also worked great for hanging GIK PolyFusors on the walls (just used one Z-bar at the top). I went with the 16" version for both places.


----------



## dnoonie

darrellh44 said:


> +1 on the Z-bars. They worked great on my ceiling panels. They also worked great for hanging GIK PolyFusors on the walls (just used one Z-bar at the top). I went with the 16" version for both places.


Cool! Glad is worked out.

I've been meaning to get some GIK PolyFusors for my back wall and back ceiling corners, maybe this winter I'll be able to do that. 

Cheers,


----------



## Mpoes12

jamesyates said:


> Hello All,
> 
> 
> 
> Just purchased a house and what is to be the media room has a very vaulted ceiling. What are the trouble spots here to deal with first? Any acoustical treatment suggestions? Will be adding ATMOS height speakers somehow and using a 7.2 surround with two subs. The screen will be about 9 feet wide and be a screen that raised from the floor like the following.
> 
> 
> 
> http://elitescreens.com/front/front/productdetail/product/161
> 
> 
> 
> Any suggestions welcome. Thank you all.




I would suggest treating a ceiling like that. At a minimum you want 2" acoustic insulation but if you can go thicker in places that's better. You don't need to cover the entire ceiling. You can treat it in spots as long as you get fairly even coverage. I would suggest finding the first reflection points on the ceiling and treating those with a thicker material. 

In rooms like that I usually suggest mostly using absorption. You can use diffusion but often you end up sitting too close for good effect and they are a lot trickier to place. 

Rooms like that can be really hard to work with bass wise. The room isn't a cube so calculations of the modes are invariably wrong. I usually just stick a subwoofer in the middle of the room and run a few sweeps. That will tell you the problem frequencies pretty quick. If you use standard bass trapping based on velocity absorption then the only thing that matter with the measurements is how low the modes go. However if you have strong modes below 80hz then you may want pressure absorbers and so it becomes trickier to place them correctly. 

Having said all that, I've had really nice results in attic rooms like that. My dad built a music room in a space over his garage and the acoustics are surprisingly good for a space that is nearly 100% reflective and massive. You may find that the natural acoustics are good and it may let you get away with less treatment. Though I'd still treat that ceiling. 


Sent from my iPhone using Tapatalk


----------



## Mpoes12

grendelrt said:


> Doh I bought some 2" Roxul 60 from Acoustimac today already. Can you get those zbar equivalent locally at lowes or somewhere (if not I can order some later once I know how many panels)? I was thinking of just building a frame for the acoustic material to keep the edges looking nice. Might actually put a back board on the frame and use spray adhesive or something to help with the droop of the roxul laying on the fabric. Any ideas on that part, I know my wall panels the roxul moves around but its not much of an issue since they aren't upside down.



You can also make your own mounts. It's just a French cleat. I made some with a sliding miter saw, but a table saw or circular saw is much smarter. I took a 1x4 and cut it length wise with a 45 degree angle or so. Z clips are cheap and easy but making your works too. 


Sent from my iPhone using Tapatalk


----------



## Mpoes12

dnoonie said:


> 2" absorbers with 703/705/Roxul works pretty well, I've switched to 4" for my front ceiling first reflection points but the 2" seemed to do a good job too. I have Roxul 4lb in the front and a mix of 4lb and 8lb in the back. I have 2" on the front sides with a 1" gap (first and second reflection points), because of space considerations I'm not going with 4".
> 
> The rule of thumb for diffusion positioning is a foot of distance for every inch of thickness for the diffusion otherwise you get image smearing (at least that's been my experience, someone with more knowledge might be able to fill in) so if you have the distance from the ceiling 1st reflection point to your seating position diffusion might work for you. Diffusion would tend to be thicker than absorption so I'm not sure it would be better for you or not.
> 
> Cheers,



Distance to a diffuser would depend on the design type. What you have suggest is generally right for a 2d QRD. You can sit much closer to stepped diffusers and somewhat closer with 3D QRD's. you can also sit very close to MLS diffusers. the width of the wells really is what tends to matter just as much or more than their depth. 

There are also a lot of people who sit way too close to their diffusers and love it. It is possible they are deaf or don't know what to listen for to realize the problem, or its possible it's not a big deal. Most of my personal experience has been with QRD and MLS diffusers. I find it irritating to sit too close to a QRD myself. I also found in my own room that I really preferred the QRD's with some absorption around them. 


Sent from my iPhone using Tapatalk


----------



## Mpoes12

grendelrt said:


> More of an aesthetic thing, I might be able to do a 2" panel or something, but I don't want anything really large hanging down if possible. With the ceiling speakers and projector could get complicated. Looking for other possibilities before I go down that road =) Didn't know if diffusion was one, I only have absorption right now and I know there is supposed to be a balance.




If you prefer the look of diffusers those would probably help. I think absorption will be more foolproof. Try 2" panels and see. It will absorb a lot of the mid and high frequencies. It should be good down to 300hz or so and I think you may find it makes a. Provable difference. If you are going with 2" you may want to go on the denser side and you may also want to think about an airgap. 

I glued my panels to the ceiling. The edges are hardened with resin and the corners have cardboard corner stiffeners adhered with resin. Then wrapped in fabric and glued with construction adhesive. I used double stick tape to hold them until the glue dried. I don't know that I would do this with a really dense panel or one with a wood frame. I'm sure the adhesive would hold but I wouldn't want to chance it. 

You can also use rotofast cloud hangers. If you do that you will need to use an owens Corning or equivalent product. I've had these pull out of mineral wool even with added resin. 

As I mentioned in a previous post, I've also made my own French cleat. I usually do it for wall hanging but I recently tested it for a ceiling panel and it worked fine. You basically make it into rails for the panel to slide into. You can even secure it with a screw to be sure the panel doesn't move around or somehow dislodge from the rail. 


Sent from my iPhone using Tapatalk


----------



## dnoonie

Mpoes12 said:


> Distance to a diffuser would depend on the design type. What you have suggest is generally right for a 2d QRD. You can sit much closer to stepped diffusers and somewhat closer with 3D QRD's. you can also sit very close to MLS diffusers. the width of the wells really is what tends to matter just as much or more than their depth.
> 
> There are also a lot of people who sit way too close to their diffusers and love it. It is possible they are deaf or don't know what to listen for to realize the problem, or its possible it's not a big deal. Most of my personal experience has been with QRD and MLS diffusers. I find it irritating to sit too close to a QRD myself. I also found in my own room that I really preferred the QRD's with some absorption around them.
> 
> 
> Sent from my iPhone using Tapatalk


Thanks for the clarification. 

I have 6" QRDs, I tried them at front first reflection points and it smeared the imaging at 5' to the MLP so I moved them to the surround position where they work great. I also have QRDs beside the front speakers (about 2/3 above the speaker and 1/3 below the speaker) and oddly it seems to have done a wonderful job of blending the front and surrounds. 

Cheers,


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## jamesyates

Mpoes12 said:


> I would suggest treating a ceiling like that. At a minimum you want 2" acoustic insulation but if you can go thicker in places that's better. You don't need to cover the entire ceiling. You can treat it in spots as long as you get fairly even coverage. I would suggest finding the first reflection points on the ceiling and treating those with a thicker material.
> 
> In rooms like that I usually suggest mostly using absorption. You can use diffusion but often you end up sitting too close for good effect and they are a lot trickier to place.
> 
> Rooms like that can be really hard to work with bass wise. The room isn't a cube so calculations of the modes are invariably wrong. I usually just stick a subwoofer in the middle of the room and run a few sweeps. That will tell you the problem frequencies pretty quick. If you use standard bass trapping based on velocity absorption then the only thing that matter with the measurements is how low the modes go. However if you have strong modes below 80hz then you may want pressure absorbers and so it becomes trickier to place them correctly.
> 
> Having said all that, I've had really nice results in attic rooms like that. My dad built a music room in a space over his garage and the acoustics are surprisingly good for a space that is nearly 100% reflective and massive. You may find that the natural acoustics are good and it may let you get away with less treatment. Though I'd still treat that ceiling.
> 
> 
> Sent from my iPhone using Tapatalk


Thank you very much for your suggestions. I will be using two subwoorfers place off the center of the room. One in front and one in back. That should help with bass issues.


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## jamesyates

Mpoes12 said:


> I would suggest treating a ceiling like that. At a minimum you want 2" acoustic insulation but if you can go thicker in places that's better. You don't need to cover the entire ceiling. You can treat it in spots as long as you get fairly even coverage. I would suggest finding the first reflection points on the ceiling and treating those with a thicker material.
> 
> In rooms like that I usually suggest mostly using absorption. You can use diffusion but often you end up sitting too close for good effect and they are a lot trickier to place.
> 
> Rooms like that can be really hard to work with bass wise. The room isn't a cube so calculations of the modes are invariably wrong. I usually just stick a subwoofer in the middle of the room and run a few sweeps. That will tell you the problem frequencies pretty quick. If you use standard bass trapping based on velocity absorption then the only thing that matter with the measurements is how low the modes go. However if you have strong modes below 80hz then you may want pressure absorbers and so it becomes trickier to place them correctly.
> 
> Having said all that, I've had really nice results in attic rooms like that. My dad built a music room in a space over his garage and the acoustics are surprisingly good for a space that is nearly 100% reflective and massive. You may find that the natural acoustics are good and it may let you get away with less treatment. Though I'd still treat that ceiling.
> 
> 
> Sent from my iPhone using Tapatalk


Thank you for your suggestions. I will be using two subwoofers off center (one in front and back). That should help a bit with bass. I would like to have them in the center of the room, but that will not be possible.


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## Mpoes12

jamesyates said:


> Thank you for your suggestions. I will be using two subwoofers off center (one in front and back). That should help a bit with bass. I would like to have them in the center of the room, but that will not be possible.




Center of the room wouldn't be a good place for them anyway, unless you mean center line but still front and back. The multisub approach relies specifically on placing he subs in areas that maximally excite the modes. While Harman tested symmetric placement, Earl Geddes specifically tested both symmetric and pseudo-random non-symmetric placement. His work suggested that exciting the modes in this pseudo-random and non-symmetric manner was better at exciting the most modes and evening out bass. However both Geddes and Harman only tested rectangular sealed rooms with even ceiling heights. Your room isn't like that so things will be a bit more unpredictable. 

I still suggest treating bass with something of for no other reason as to help with the ringing. I don't recall mention of damping in the models that Harman did, but I know in his PhD dissertation Geddes did include damping in his modeling and found it beneficial. He aspouses the heavy use of bass trapping in the form of both CLD walls and thick treatments on the front wall. In fact one unfortunate part of his concept never being published (outside of his dissertation) is that it has created some confusion around what his research found and thus what he suggest. His approach is a system approach and he damping is a big part of it. I've found that in practice multi-subs helps but there is still no replacement for good room design and acoustic treatment. 

Certainly test it without treatment and see how it works out. You never know. Especially when the ceiling shape, sometimes you get lucky and magical things happen. 


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## ChadS13TDI

Please Help! I need some advice on Acoustical treatments for my space. I am having a really hard time understanding what I need. I would like to start with a basic setup and then look to maybe add to it. I am open to DIY but I really don't have time and would like to hear some cost effective options of buying premade stuff. It really needs to look nice too as the wife will get upset if it looks tacky, etc. Here is some pictures of the space to give you an idea. 


Here is what I am thinking so far and please correct, change or add as you see fit. It's a slippery slope so I'd like to start small. Which would be best walls to tackle first? 




1 2x4 panel on each side of screen on screen wall
2 2x4 panels hanging vertically on the right wall (when facing screen)
2 2x4 panels on rear wall behind bar seating.
1 wall art panel on right wall in rear kitchen area
2 2x4 panels on far left wall which will be an area where shuffle board and foosball table go.
1 wall art panel on rear wall of the shuffle board and foosball table area above small couch.
Any help would be much appreciated! 


DSC02025 by ChadS99SVT, on Flickr


DSC02043 by ChadS99SVT, on Flickr


IMG_0888 by ChadS99SVT, on Flickr


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## jamesyates

Mpoes12 said:


> Center of the room wouldn't be a good place for them anyway, unless you mean center line but still front and back. The multisub approach relies specifically on placing he subs in areas that maximally excite the modes. While Harman tested symmetric placement, Earl Geddes specifically tested both symmetric and pseudo-random non-symmetric placement. His work suggested that exciting the modes in this pseudo-random and non-symmetric manner was better at exciting the most modes and evening out bass. However both Geddes and Harman only tested rectangular sealed rooms with even ceiling heights. Your room isn't like that so things will be a bit more unpredictable.
> 
> I still suggest treating bass with something of for no other reason as to help with the ringing. I don't recall mention of damping in the models that Harman did, but I know in his PhD dissertation Geddes did include damping in his modeling and found it beneficial. He aspouses the heavy use of bass trapping in the form of both CLD walls and thick treatments on the front wall. In fact one unfortunate part of his concept never being published (outside of his dissertation) is that it has created some confusion around what his research found and thus what he suggest. His approach is a system approach and he damping is a big part of it. I've found that in practice multi-subs helps but there is still no replacement for good room design and acoustic treatment.
> 
> Certainly test it without treatment and see how it works out. You never know. Especially when the ceiling shape, sometimes you get lucky and magical things happen.
> 
> 
> Sent from my iPhone using Tapatalk


thanks for your help. I meant to write I would like to place each subwoofer at the center line of the front and back walls. However, I am unable due to the center speaker in front and french doors at the rear of the room. I found the following article very interesting. 

https://www.harman.com/sites/default/files/multsubs_0.pdf


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## Mpoes12

jamesyates said:


> thanks for your help. I meant to write I would like to place each subwoofer at the center line of the front and back walls. However, I am unable due to the center speaker in front and french doors at the rear of the room. I found the following article very interesting.
> 
> 
> 
> https://www.harman.com/sites/default/files/multsubs_0.pdf




That would be the Harman article I was mentioning. I personally use Geddes approach and prefer his findings. His actual dissertation is very math heavy and doesn't discuss subwoofer placement, just low frequency reproduction (conceptually the same thing). However there are some write ups on his approach floating around.


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## grendelrt

Just realized I put this in the wrong thread lol, pls ignore


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## grendelrt

I found all the reflection points on my ceiling for my front 3 speakers. An 8ft length looks like should cover all 3 points. I have some roxul 60 48x24x2 panels. Is there a recommended width I should follow? I figure 2ft minimum, wondering if I should go wider though. I am going to use 1x3 wood to make frames allowing a small air gap.


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## LydMekk

2 foot wide is standard, as is 4 foot high. But as long as you have enough on the spot for the reflections ( aka if it's bigger) you're good.


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## Mpoes12

grendelrt said:


> I found all the reflection points on my ceiling for my front 3 speakers. An 8ft length looks like should cover all 3 points. I have some roxul 60 48x24x2 panels. Is there a recommended width I should follow? I figure 2ft minimum, wondering if I should go wider though. I am going to use 1x3 wood to make frames allowing a small air gap.




Depends a lot on your speakers. A speakers radiation pattern depends heavily on the design and in some cases first reflections really become a non-issue. I would argue the 2x4 panel size is just a reflection of standard sizing of the insulation and standardization in the industry. It's not a reflection of the amount of surface area coverage needed to absorb first reflections. 

Some speakers have really smooth broad dispersion over a very wide set of angles. These speakers are going to be radiating a near omnidirectional Pattern over much of he ceiling, walls, and floor in front of the speaker. In this scenario you need a lot of coverage. A true CD speaker, especially one with 90 degrees or less radiation down to a low enough frequency (under 1khz) likely needs no coverage on the first reflection points. 

I have CD speakers with roughly 90 degree dispersion down to 700hz or so. I really don't need first reflection point absorption. However I did install hybrid panels on my ceiling and walls, but took efforts to increase there LF absorption. In my case the panels cover roughly 4' of depth and 8' of width on the ceiling and 4'x4' on the wall. The area behind my screen is fully 100% covered in 2" to 6" thick of absorption. In addition one corner has a bass trap (the other has a subwoofer currently). One reason I did this is that a surprisingly high degree of sound radiates from the back and side of enclosures. Some research has been done to measure this effect including how much of this sound reflects off walls and contributes to the early reflections. They found it sufficiently high to add problems. While I took steps to. Hold my speakers to be very good at isolating sound (CLD walls and high mass) I figured absorbing around and behind the speakers was also a good idea. 



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## GatorBlues

*Basics?*

I'm building a room in my new house. A rough sketch of the plan is attached. I've been reading up in this thread, but as it gets more and more detailed, I start questioning everything I thought I learned in the early parts of the thread. Are the basics from the beginning of this thread still the general consensus for an initial build? In other words, should I do the following: 

(1) add Linacoustic (or Roxul 60) all the way around the room up to 48" (and if so, what thickness? 1", 2", two layers of 1", or alternate between 1" and 2" around the room), 

(2) leave the drywall as is above that, and 

(3) treat the entire front wall (including behind the AT screen) with two layers of 1" Linacoustic separated by a 3 mil plastic sheet?


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## Mpoes12

GatorBlues said:


> I'm building a room in my new house. A rough sketch of the plan is attached. I've been reading up in this thread, but as it gets more and more detailed, I start questioning everything I thought I learned in the early parts of the thread. Are the basics from the beginning of this thread still the general consensus for an initial build? In other words, should I do the following:
> 
> 
> 
> (1) add Linacoustic (or Roxul 60) all the way around the room up to 48" (and if so, what thickness? 1", 2", two layers of 1", or alternate between 1" and 2" around the room),
> 
> 
> 
> (2) leave the drywall as is above that, and
> 
> 
> 
> (3) treat the entire front wall (including behind the AT screen) with two layers of 1" Linacoustic separated by a 3 mil plastic sheet?




That approach came from the style of one particular very well respected and knowledgeable home theater installer (Erskine). There are lots of good ways to solve the acoustics of a theater and few can be applied universally without accounting for the rooms size, shape, construction, etc. that approach has been one that has worked well for many. Having said that, it's not the approach I took or have used with others.

The above mentioned approach is designed to mitigate early reflections and tame the low frequencies around the front of the room and to evenly lower the RT60 value. I would call it somewhat consistent with the LEDE room as the front is made fairly dead. The plastic increases LF absorption slightly while reducing the lower midrange absorption somewhat. That is good because (for whatever reason) many home theaters have too much absorption in the 300-500hz range. You want to have the flatest RT60 value you can have. In a perfect world it would be around .21-.25 from 20hz to 20khz. That isn't realistic so we usually focus on the 100hz to 10,000hz range and accept a rising RT60 value below 200hz or so. In my room I had a dip in the RT60 value of the mostly untreated room at 500hz. My room averages about .32 with just carpet and one 2" layer of insulation on the front wall, but at 500hz it was .24. Had I lined the entire room with 2"-4" insulation including the front of the room, everything would drop above 300hz and the 500hz dip would be even worse. At the moment my RT60 is flat down to 300hz and then rises as the frequency lowers. I'm working on fixing that still but that's the hardest area to fix too. 

So how does this answer your question? That is a good generic approach but it's not a panacea and not doing that isn't automatically wrong. Understanding the physics is tricky and most don't have time or will to learn it, so a general suggestion makes life easy. It is totally possible that following that approach in some rooms could yield poor results. 


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## VideoGrabber

Mpoes12 said:


> I did install hybrid panels on my ceiling and walls, but took efforts to increase there[sic] LF absorption. In my case the panels cover *roughly 4' of depth* and 8' of width on the ceiling and 4'x4' on the wall.


Did you really mean 4-feet of depth? Perhaps you're using 'depth' in a different way than I might.



> The area behind my screen is fully 100% covered in 2" to 6" thick of absorption.


This is your spandex AT screen, correct?

In some small-room configurations, surround-sound speakers can also throw a fair amount of sound at the screen. If it is AT, then absorption behind it may help reduce unwanted first reflections from that source.


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## VideoGrabber

Mpoes12 said:


> A true CD speaker, especially one with 90 degrees or less radiation down to a low enough frequency (under 1khz) likely needs no coverage on the first reflection points.


Another factor beyond the dispersion characteristics of the speakers that can be a contributor is to what degree you have them toed in. Aimed at the MLP will result in less 1st-reflection influence than if they are aimed straight out (i.e., perpendicular). (And crossed in front, even less so.) So if your primary first-reflection from the right speaker is coming at you from the left, that will be a different situation than if it is coming from the right, and interfering/competing with the direct sound.


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## GatorBlues

Mpoes12 said:


> That approach came from the style of one particular very well respected and knowledgeable home theater installer (Erskine). There are lots of good ways to solve the acoustics of a theater and few can be applied universally without accounting for the rooms size, shape, construction, etc. that approach has been one that has worked well for many. Having said that, it's not the approach I took or have used with others.
> 
> The above mentioned approach is designed to mitigate early reflections and tame the low frequencies around the front of the room and to evenly lower the RT60 value. I would call it somewhat consistent with the LEDE room as the front is made fairly dead. The plastic increases LF absorption slightly while reducing the lower midrange absorption somewhat. That is good because (for whatever reason) many home theaters have too much absorption in the 300-500hz range. You want to have the flatest RT60 value you can have. In a perfect world it would be around .21-.25 from 20hz to 20khz. That isn't realistic so we usually focus on the 100hz to 10,000hz range and accept a rising RT60 value below 200hz or so. In my room I had a dip in the RT60 value of the mostly untreated room at 500hz. My room averages about .32 with just carpet and one 2" layer of insulation on the front wall, but at 500hz it was .24. Had I lined the entire room with 2"-4" insulation including the front of the room, everything would drop above 300hz and the 500hz dip would be even worse. At the moment my RT60 is flat down to 300hz and then rises as the frequency lowers. I'm working on fixing that still but that's the hardest area to fix too.
> 
> So how does this answer your question? That is a good generic approach but it's not a panacea and not doing that isn't automatically wrong. Understanding the physics is tricky and most don't have time or will to learn it, so a general suggestion makes life easy. It is totally possible that following that approach in some rooms could yield poor results.
> 
> 
> Sent from my iPhone using Tapatalk


I need to decide what to have the builder do for me during the initial construction. Obviously, anything I can have him do makes life easier. Would you recommend that I treat the front wall with 1" lin/3 mil plastic/1" lin and then evaluate how the room does from there after I move in and set it up?


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## Mpoes12

VideoGrabber said:


> Did you really mean 4-feet of depth? Perhaps you're using 'depth' in a different way than I might.
> 
> 
> 
> This is your spandex AT screen, correct?
> 
> In some small-room configurations, surround-sound speakers can also throw a fair amount of sound at the screen. If it is AT, then absorption behind it may help reduce unwanted first reflections from that source.




I did mean to say depth so I think I am using the term differently. I don't mean depth as in the height from the ceiling. I mean it extends 4' from the screen toward the listener along the length of the room and is 8' along the width of the room. I consider the front to back to be depth.


Yes I have a spandex screen and yes I mean the area behind it. My setup, like many on these forums, uses a portion of the front room to hide the speakers and some of the subwoofers. I have a false wall to cover them and the entire wall is acoustically transparent. I went with extra depth to allow for larger subwoofers (Because AVS is a bad influence) and so I have a 30" deep by 11' wide space that has every surface covered in insulation. 


I may not be understanding your comment about throwing sound at the screen. Do you mean the surround speakers (as in effect speakers) that are on the side and rear of the room? If yes, then I would imagine they always throw sound at the screen to some extent and certainly in smaller rooms they would throw more. I would question the need to absorb or diffuse that sound simply because it should be fairly late arrival. The room would need to be really small (and if it is, then I would agree, absorbing that off the rear and front wall would help give an illusion of a larger room). Even then, the temporal difference between the direct sound and the reflected sound from the front of the room would be so great (relative to the size of the room) that it shouldn't have a big effect on clarity. Our ears should actually filter that out largely. 


As to your comment about aiming the CD speakers, I would argue that CD speakers were designed specifically to be aimed in the way you mention. They SHOULD be aggressively toed in and using them straight on is the INCORRECT way to use CD speakers. Bill's paper, Dr. Geddes, Harman, Peavey, etc. have all referenced or pushed the concept (and I'm sure there are more I'm not aware of). In talking with some guys that design recording studio's, I was told that the aggressive toe of CD speakers has been the common practice and wisdom of the field for decades. I know there will be people who disagree and prefer something and of course you can do what you want with your own speakers. I just feel that the argument for aggressive toe is based on solid objective concepts that make too much sense to ignore.


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## Mpoes12

GatorBlues said:


> I need to decide what to have the builder do for me during the initial construction. Obviously, anything I can have him do makes life easier. Would you recommend that I treat the front wall with 1" lin/3 mil plastic/1" lin and then evaluate how the room does from there after I move in and set it up?



You can do that, I do think treating the wall is critical. I don't know where Erskine landed in his recommendation, I feel like the specifics of the suggestion have changed. I used and prefer to use 2" instead of 1". I know that when asked by another acoustic expert about why he used the plastic and why he preferred less depth, he noted that having a full 4" or more of insulation caused too much absorption at around 500hz. I had thought he was nuts as the common wisdom had been (at least amongst the studio guys) that thicker is better because it extends the LF absorption and most rooms have far too much midrange and HF absorption and not nearly enough LF. When I took measurements of my converted bedroom theater, I did not have this problem. There was no dip in the RT60 at 500hz. When I measured my new soundproof purpose built theater, I did have an unusual dip in the RT60 curve at 500hz. Where as most of the range was around .32s, it dipped to .24s at 500hz. One thing people sometimes forget is that even 1" insulation will absorb 100% of the incident sound (or darn near 100%) above a certain frequency. Going with 2" extends the lower frequency in which 100% of the incident sound is absorbed, but it doesn't absorb any more sound above that point since 100% of it was absorbed. If you go to 4" then again, the LF number is pushed down.


A 2" thick panel typically rolls off its absorption starting below 400hz. A 4" panel starts to move that down to 300hz and usually rolls off in a more shallow manner. If rooms tend to have too much absorption at 500hz then you can see that even a 2" panel is absorbing a bit too much. However, none of this changes the fact that pretty much every room in existence does not have nearly enough absorption below 300hz. The plastic helps reduce some of the midrange/midbass absorption and would increase the LF absorption a decent amount potentially. How much depends on the thickness of the fiberglass behind the plastic. That is why I prefer the thicker 2" absorption myself. I also found that once I installed the first 2" absorption material layer on my front wall, the dip at 500hz in the RT60 went away, it flattened out largely, and what remained was a fairly flat curve that rose dramatically below 200hz. In other words, even without the plastic, my room suddenly had a flat curve but without enough LF absorption. 


That means you really need to measure because every room could be different. While I added plastic to a portion of the wall, I also added a lot more insulation to sections of the wall to help. I still do not have nearly enough LF absorption and plan to add a bunch more bass traps in the future. I even have a large corner trap that goes floor to ceiling and is 24' across, but that actually did very little.


----------



## GatorBlues

Mpoes12 said:


> You can do that, I do think treating the wall is critical. I don't know where Erskine landed in his recommendation, I feel like the specifics of the suggestion have changed. I used and prefer to use 2" instead of 1". I know that when asked by another acoustic expert about why he used the plastic and why he preferred less depth, he noted that having a full 4" or more of insulation caused too much absorption at around 500hz. I had thought he was nuts as the common wisdom had been (at least amongst the studio guys) that thicker is better because it extends the LF absorption and most rooms have far too much midrange and HF absorption and not nearly enough LF. When I took measurements of my converted bedroom theater, I did not have this problem. There was no dip in the RT60 at 500hz. When I measured my new soundproof purpose built theater, I did have an unusual dip in the RT60 curve at 500hz. Where as most of the range was around .32s, it dipped to .24s at 500hz. One thing people sometimes forget is that even 1" insulation will absorb 100% of the incident sound (or darn near 100%) above a certain frequency. Going with 2" extends the lower frequency in which 100% of the incident sound is absorbed, but it doesn't absorb any more sound above that point since 100% of it was absorbed. If you go to 4" then again, the LF number is pushed down.
> 
> 
> A 2" thick panel typically rolls off its absorption starting below 400hz. A 4" panel starts to move that down to 300hz and usually rolls off in a more shallow manner. If rooms tend to have too much absorption at 500hz then you can see that even a 2" panel is absorbing a bit too much. However, none of this changes the fact that pretty much every room in existence does not have nearly enough absorption below 300hz. The plastic helps reduce some of the midrange/midbass absorption and would increase the LF absorption a decent amount potentially. How much depends on the thickness of the fiberglass behind the plastic. That is why I prefer the thicker 2" absorption myself. I also found that once I installed the first 2" absorption material layer on my front wall, the dip at 500hz in the RT60 went away, it flattened out largely, and what remained was a fairly flat curve that rose dramatically below 200hz. In other words, even without the plastic, my room suddenly had a flat curve but without enough LF absorption.
> 
> 
> That means you really need to measure because every room could be different. While I added plastic to a portion of the wall, I also added a lot more insulation to sections of the wall to help. I still do not have nearly enough LF absorption and plan to add a bunch more bass traps in the future. I even have a large corner trap that goes floor to ceiling and is 24' across, but that actually did very little.


Just to make sure I'm understanding, for the front wall, are you suggesting 2 layers of 2" with a plastic layer in the middle? Or just two layers of 2"? Again, the builder will be long gone and the room finished before I have a chance to install the sound system and even think about learning how to take measurements. So the idea is to do what can be done while still leaving the option to adjust later with as little additional building work as possible. 

Also, with respect to LF, I have been reading about putting A/C vents into the back of my 10 foot long, 16 foot wide, 16" high riser, which will be filled with insulation. I won't know how effective that turns out to be until the room is finished and I install a sound system, of course. 

Thanks for all of your help.


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## Mpoes12

GatorBlues said:


> Just to make sure I'm understanding, for the front wall, are you suggesting 2 layers of 2" with a plastic layer in the middle? Or just two layers of 2"? Again, the builder will be long gone and the room finished before I have a chance to install the sound system and even think about learning how to take measurements. So the idea is to do what can be done while still leaving the option to adjust later with as little additional building work as possible.
> 
> Also, with respect to LF, I have been reading about putting A/C vents into the back of my 10 foot long, 16 foot wide, 16" high riser, which will be filled with insulation. I won't know how effective that turns out to be until the room is finished and I install a sound system, of course.
> 
> Thanks for all of your help.



2" insulation/plastic/2" insulation is my suggestion. I was just making the point that this isn't guaranteed to be better. You are asking for generic acoustic advice which is akin to asking a tire salesman his opinion on the best tires for your car without telling him what car you have or how you will use it. Even in this analogy, telling a person what car you have tells them a lot about that car because of all the data that is available. Telling me about your room actually doesn't help because I don't have data. 


As for LF absorption, yes the riser should provide some LF absorption. For the most part nobody knows how this will work until they have it all setup and done. It is theoretically possible to model the behavior, but most of us don't have access to such software. I've tried to model the behavior but a poor match between my model and reality. Here is what I can say, it makes the most sense to place the vents near boundaries. This is because these are areas of high pressure and where Bass is building up. This would be along the walls, with the corners being the most important area. There is likely to be a Helmholtz resonance from these and I believe that is part of how these operate. The volume of the box is so great that you actually need quite a few vents just to get the resonance up into the 20-30hz range or higher. 


I'll just add that these riser bass traps are better than nothing, they help, but I do not consider them significant bass trapping and I have not experienced them contributing significantly. Basically, I don't have them to pull down the LF RT60 values nor do they seem to make huge differences in the LF decay or flatness. No reason not to do it, but you usually still need more.


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## grendelrt

Measuring out my ceiling panel, I have 2 ceiling speakers (HTR7000) that are angled drivers for Atmos duty. I am using 1 x 3s to do the framing (so 2.5 in depth actual dimension) and was wondering if there was a guideline of how close I can get to the side of that speaker without interfering with it?


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## Mpoes12

grendelrt said:


> Measuring out my ceiling panel, I have 2 ceiling speakers (HTR7000) that are angled drivers for Atmos duty. I am using 1 x 3s to do the framing (so 2.5 in depth actual dimension) and was wondering if there was a guideline of how close I can get to the side of that speaker without interfering with it?




Can you give more detail. What exactly are you referring to? What is an HTR7000 and what kind of ceiling panels. Do you mean acoustic panels on the ceiling? Is the HTR7000 a speaker and is it an in ceiling that is flush with the ceiling? If that is the case then you should reconsider. If it's anywhere near the speaker it will provide a hard reflective surface and will likely cause a lot of diffraction. Beside impacting the overall sound quality of the speaker it will also play into a mechanism the ear uses to locate sounds. It makes be speakers easier to locate and reduces the seamless pan you would otherwise get. 

What I would do if that is the case is build the panels differently. You will want a panel that is open on the sides so sound hitting the sides can be absorbed. You could cut a lot of holes in the frame but it will still cause some diffraction around the edges. You could build a frame using a more open material like metal drywall edging. You could also use thick acoustic foam (which is really just open cell PU foam and wrap that in fabric. If you go this route then don't buy the acoustic foam with patterns or egg crate cut into it. You want a 3-4" thick sheet. It will weigh quite a bit less which is nice and actually absorbs about the same as fiberglass. 

Another option could be to mount the speakers flush with the panels by building external boxes for them. That isn't a bad option either. As long as they are flush with the panels it won't cause problems. 


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## Mpoes12

grendelrt said:


> Measuring out my ceiling panel, I have 2 ceiling speakers (HTR7000) that are angled drivers for Atmos duty. I am using 1 x 3s to do the framing (so 2.5 in depth actual dimension) and was wondering if there was a guideline of how close I can get to the side of that speaker without interfering with it?




Can you give more detail. What exactly are you referring to? What is an HTR7000 and what kind of ceiling panels. Do you mean acoustic panels on the ceiling? Is the HTR7000 a speaker and is it an in ceiling that is flush with the ceiling? If that is the case then you should reconsider. If it's anywhere near the speaker it will provide a hard reflective surface and will likely cause a lot of diffraction. Beside impacting the overall sound quality of the speaker it will also play into a mechanism the ear uses to locate sounds. It makes be speakers easier to locate and reduces the seamless pan you would otherwise get. 

What I would do if that is the case is build the panels differently. You will want a panel that is open on the sides so sound hitting the sides can be absorbed. You could cut a lot of holes in the frame but it will still cause some diffraction around the edges. You could build a frame using a more open material like metal drywall edging. You could also use thick acoustic foam (which is really just open cell PU foam and wrap that in fabric. If you go this route then don't buy the acoustic foam with patterns or egg crate cut into it. You want a 3-4" thick sheet. It will weigh quite a bit less which is nice and actually absorbs about the same as fiberglass. 

Another option could be to mount the speakers flush with the panels by building external boxes for them. That isn't a bad option either. As long as they are flush with the panels it won't cause problems. 


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## grendelrt

Mpoes12 said:


> Can you give more detail. What exactly are you referring to? What is an HTR7000 and what kind of ceiling panels. Do you mean acoustic panels on the ceiling? Is the HTR7000 a speaker and is it an in ceiling that is flush with the ceiling? If that is the case then you should reconsider. If it's anywhere near the speaker it will provide a hard reflective surface and will likely cause a lot of diffraction. Beside impacting the overall sound quality of the speaker it will also play into a mechanism the ear uses to locate sounds. It makes be speakers easier to locate and reduces the seamless pan you would otherwise get.
> 
> What I would do if that is the case is build the panels differently. You will want a panel that is open on the sides so sound hitting the sides can be absorbed. You could cut a lot of holes in the frame but it will still cause some diffraction around the edges. You could build a frame using a more open material like metal drywall edging. You could also use thick acoustic foam (which is really just open cell PU foam and wrap that in fabric. If you go this route then don't buy the acoustic foam with patterns or egg crate cut into it. You want a 3-4" thick sheet. It will weigh quite a bit less which is nice and actually absorbs about the same as fiberglass.
> 
> Another option could be to mount the speakers flush with the panels by building external boxes for them. That isn't a bad option either. As long as they are flush with the panels it won't cause problems.
> 
> 
> Sent from my iPhone using Tapatalk


Yeah its a flush mount speaker with an angled driver instead of pointing straight down. I've already built the panels now, they are 3" deep. It's looking like the panel side will be about 12 " away from the side of the hole where the speaker is. I just looked up the install guidelines for the speakers and they say to stay 12" from a wall, so I am thinking I will be OK since my panel only extends down 3" vs a wall (fingers crossed).


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## OKGeek

*Absorption layout*

Hi, there. Planning HT as a part of living room, which is remodelled from scratch. Based on preliminary research ended up with the following absorption layout. Would appreciate any thoughts and feedback on suggested approach.

Speakers layout: 5.1.4 (with further upgrade to 7.1.4)
Bed layer: on-wall Totem Tribe II/III. Though on-walls (not in-walls), want to mount them flush to absorption surface.
Top layer: in-ceiling Totem Masks

Front wall
AT woven screen and AT fabric panels around
2'' 703 with 2'' gap (can be increased 2''-3'' more if necessary), floor to ceiling across the whole wall

Side wall 1
2'' 703 with 2'' gap, 1'x2' panel

Side wall 2
Nothing as it's far away to the right and will have bookshelves, which will act as absorbers anyway

Back wall
2'' 703 with 2'' gap, floor to ceiling

Corners (bass traps)
4'' 703 with 4'' average (0'' to 8'') air gap, floor to ceiling, 1' wide
Additional corner trap can be introduced between front wall and ceiling

Ceiling and floor
As it's part of the living room, not sure if it can be cured somehow, aside of the thick carpet on the floor in front of the couch.

Material
703 2'' or 4'' thick (depending on application). Shall I introduce FRK/plastic at some places (corners?) ?

Thanks!


----------



## Mpoes12

OKGeek said:


> Hi, there. Planning HT as a part of living room, which is remodelled from scratch. Based on preliminary research ended up with the following absorption layout. Would appreciate any thoughts and feedback on suggested approach.
> 
> 
> 
> Speakers layout: 5.1.4 (with further upgrade to 7.1.4)
> 
> Bed layer: on-wall Totem Tribe II/III. Though on-walls (not in-walls), want to mount them flush to absorption surface.
> 
> Top layer: in-ceiling Totem Masks
> 
> 
> 
> Front wall
> 
> AT woven screen and AT fabric panels around
> 
> 2'' 703 with 2'' gap (can be increased 2''-3'' more if necessary), floor to ceiling across the whole wall
> 
> 
> 
> Side wall 1
> 
> 2'' 703 with 2'' gap, 1'x2' panel
> 
> 
> 
> Side wall 2
> 
> Nothing as it's far away to the right and will have bookshelves, which will act as absorbers anyway
> 
> 
> 
> Back wall
> 
> 2'' 703 with 2'' gap, floor to ceiling
> 
> 
> 
> Corners (bass traps)
> 
> 4'' 703 with 4'' average (0'' to 8'') air gap, floor to ceiling, 1' wide
> 
> Additional corner trap can be introduced between front wall and ceiling
> 
> 
> 
> Ceiling and floor
> 
> As it's part of the living room, not sure if it can be cured somehow, aside of the thick carpet on the floor in front of the couch.
> 
> 
> 
> Material
> 
> 703 2'' or 4'' thick (depending on application). Shall I introduce FRK/plastic at some places (corners?) ?
> 
> 
> 
> Thanks!




I think your plan sounds good. Do you have an ability to take measurements. Without knowing the RT60 values or having real measurements of the effect of the room modes it's hard to give better advice. If the room is highly reflective you may need more panels. If it's got an uneven RT60 plot you may need to use it more strategically or even use 1" panels in places. Measurements would be the best first step before committing. Remember you don't need it fully setup. One relatively full range speaker (bass solid down to 50hz is more than fine) is adequate for this. 

Placing 4" 703 sheets across corners does give more bass absorption. Adding FRK will reduce the high frequency absorption and slightly increase LF absorption. This is often good but should be decided again by measurements. Also, when the traps go floor to ceiling it creates a cavity that can resonate. This can make for an uneven absorption with weird peaks and dips. It's causes by trapped standing waves basically. The fix is to break up the chamber with 703. You can either switch to a super chunk style (cut triangles stacked in the corner) or just add a few triangles every so many feet. The two would actually perform very similarly overall. 


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## OKGeek

Mpoes12 said:


> I think your plan sounds good. Do you have an ability to take measurements. Without knowing the RT60 values or having real measurements of the effect of the room modes it's hard to give better advice. If the room is highly reflective you may need more panels. If it's got an uneven RT60 plot you may need to use it more strategically or even use 1" panels in places. Measurements would be the best first step before committing. Remember you don't need it fully setup. One relatively full range speaker (bass solid down to 50hz is more than fine) is adequate for this.


Thanks, man! I didn't think about RT60 uniformity, so it's great you've mentioned that. Currently in design stage, so measurements will be available a bit further along the way. Will definitely post here.




Mpoes12 said:


> Also, when the traps go floor to ceiling it creates a cavity that can resonate. This can make for an uneven absorption with weird peaks and dips. It's causes by trapped standing waves basically. The fix is to break up the chamber with 703. You can either switch to a super chunk style (cut triangles stacked in the corner) or just add a few triangles every so many feet. The two would actually perform very similarly overall.


Awesome. That's for sure was not on my radar. Impression was that the more bass traps I have, the better, but I see, that not all basstraps are created equal


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## Mpoes12

OKGeek said:


> Thanks, man! I didn't think about RT60 uniformity, so it's great you've mentioned that. Currently in design stage, so measurements will be available a bit further along the way. Will definitely post here.
> 
> 
> 
> 
> Awesome. That's for sure was not on my radar. Impression was that the more bass traps I have, the better, but I see, that not all basstraps are created equal



RT60 Uniformity is important as a means of understanding the listenability of a room. In more tangible terms, when a room has really good decay in the mid and high frequencies, but poor decay in the bass, a room may have clear dialogue but sound boomy. Conversely, a room with good bass decay but poor mid/high decay may lack speech intelligibility, may have audible echo issues, etc. Notches in the decay can make it sound unnatural. The actual decay of the instruments or recording are already on the recording, so you don't want the room to contribute to that.


I really think that the main reason for keeping the RT60 values over .2 seconds is really more because a room that is too dead is uncomfortable, and the reason to move music rooms above .3 is just because a lot of recordings don't have good "room sound" unless they are a more natural or acoustic recording. It also wouldn't be possible to get bass decay that low and I do think having an even/flat RT60 value over the widest possible frequency range sounds more natural.


In terms of bass trapping, the more the better is mostly true, but certainly not all bass traps are created equally. Corners of rooms are very special places acoustically and need to be treated in very special ways. It's a lot more efficient of acoustic material to simply place 4"-6" panels across a corner instead of chunks, and they actually absorb, overall, very similarly to solid chunk absorbers, however if the material is too thin and doesn't break up all paths that the waves reflect in, you can get a less ideal absorption. Some commercial options have solved this simply by placing "shelves" of acoustic material up the length of the trap at periodic positions. 


My main concern with over-use of full range bass traps is the RT60 problem. As an example, the GIK tritrap is nearly flat from 80hz to 250hz in absorption. The Monster bass trap is similarly flat out to 500hz or so. With numerous 4" panels also in the room you can end up with too much absorption at 200hz to 500hz and so its not uncommon to see a notch in the RT60.


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## OKGeek

Mpoes12 said:


> RT60 Uniformity is important as a means of understanding the listenability of a room. In more tangible terms, when a room has really good decay in the mid and high frequencies, but poor decay in the bass, a room may have clear dialogue but sound boomy. Conversely, a room with good bass decay but poor mid/high decay may lack speech intelligibility, may have audible echo issues, etc. Notches in the decay can make it sound unnatural. The actual decay of the instruments or recording are already on the recording, so you don't want the room to contribute to that.
> 
> 
> I really think that the main reason for keeping the RT60 values over .2 seconds is really more because a room that is too dead is uncomfortable, and the reason to move music rooms above .3 is just because a lot of recordings don't have good "room sound" unless they are a more natural or acoustic recording. It also wouldn't be possible to get bass decay that low and I do think having an even/flat RT60 value over the widest possible frequency range sounds more natural.
> 
> 
> In terms of bass trapping, the more the better is mostly true, but certainly not all bass traps are created equally. Corners of rooms are very special places acoustically and need to be treated in very special ways. It's a lot more efficient of acoustic material to simply place 4"-6" panels across a corner instead of chunks, and they actually absorb, overall, very similarly to solid chunk absorbers, however if the material is too thin and doesn't break up all paths that the waves reflect in, you can get a less ideal absorption. Some commercial options have solved this simply by placing "shelves" of acoustic material up the length of the trap at periodic positions.
> 
> 
> My main concern with over-use of full range bass traps is the RT60 problem. As an example, the GIK tritrap is nearly flat from 80hz to 250hz in absorption. The Monster bass trap is similarly flat out to 500hz or so. With numerous 4" panels also in the room you can end up with too much absorption at 200hz to 500hz and so its not uncommon to see a notch in the RT60.


Amazing! Thank you very much for sharing all that!

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## grendelrt

For anyone who has made acoustic panels for their ceiling, I am looking for some examples of a good build. I ran into issues mounting mine with Z clips due to how close the tolerance is on them. I am probably going back to the drawing board and making a couple new panels, but looking for ideas on how to make them to facilitate easy mounting. Currently I am thinking a 1x2 + quater round frame, then adding a spacer below each z clip on the ceiling and panel to give a little extra tolerance. I think doing a fabric wrapped frameless panel with a drywall holder directly into the roxul would be the easiest, but I don't think it would hold up over time. So any one who has done ceiling panels, preferably flush against the ceiling or close to it, please share your build =) Thanks!!


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## Mpoes12

grendelrt said:


> For anyone who has made acoustic panels for their ceiling, I am looking for some examples of a good build. I ran into issues mounting mine with Z clips due to how close the tolerance is on them. I am probably going back to the drawing board and making a couple new panels, but looking for ideas on how to make them to facilitate easy mounting. Currently I am thinking a 1x2 + quater round frame, then adding a spacer below each z clip on the ceiling and panel to give a little extra tolerance. I think doing a fabric wrapped frameless panel with a drywall holder directly into the roxul would be the easiest, but I don't think it would hold up over time. So any one who has done ceiling panels, preferably flush against the ceiling or close to it, please share your build =) Thanks!!




Are you against gluing them to the ceiling?


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## grendelrt

Mpoes12 said:


> Are you against gluing them to the ceiling?
> 
> 
> Sent from my iPhone using Tapatalk


Hmmm I am guessing that would mean destroying the drywall to get them down.....so probably shouldnt do that, but out of curiosity, how would that work? Would they still be framed?


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## Mpoes12

grendelrt said:


> Hmmm I am guessing that would mean destroying the drywall to get them down.....so probably shouldnt do that, but out of curiosity, how would that work? Would they still be framed?




They certainly could be. There are strong adhesives these days, but no it is better to not frame them. Usually you harden the edges with resin. 

It's hard to do what you are asking. I made wooden French cleats for my last build that they slid into but it limited my options so I glued them this time. However I'm using a vicoustic melamine foam and wood panel so the weight is low enough for silicone adhesive which can be peeled off later. 

For what it's worth if we are talking 2"-4" panels. Acoustic foam that is solid rather than with a cut pattern has about the same absorption as fiberglass of the same size. The test data for vicoustic cinema panels with fabric cover is nearly identical to the Gik spot panels and both are the same thickness. Foam is known to absorb better for its weight/density than fiberglass which is why it's more widely used in things like aerospace industry where you need the most performance with the least weight. It's biggest problem is that it's significantly more expensive. A 4" thick sheet of PU acoustic foam in a 2x4 size is about $100 or so. 

If that opens up options and you don't need that much it may be worth considering. 


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## grendelrt

Mpoes12 said:


> They certainly could be. There are strong adhesives these days, but no it is better to not frame them. Usually you harden the edges with resin.
> 
> It's hard to do what you are asking. I made wooden French cleats for my last build that they slid into but it limited my options so I glued them this time. However I'm using a vicoustic melamine foam and wood panel so the weight is low enough for silicone adhesive which can be peeled off later.
> 
> For what it's worth if we are talking 2"-4" panels. Acoustic foam that is solid rather than with a cut pattern has about the same absorption as fiberglass of the same size. The test data for vicoustic cinema panels with fabric cover is nearly identical to the Gik spot panels and both are the same thickness. Foam is known to absorb better for its weight/density than fiberglass which is why it's more widely used in things like aerospace industry where you need the most performance with the least weight. It's biggest problem is that it's significantly more expensive. A 4" thick sheet of PU acoustic foam in a 2x4 size is about $100 or so.
> 
> If that opens up options and you don't need that much it may be worth considering.
> 
> 
> Sent from my iPhone using Tapatalk


Thanks for the reply, yeah I am doing a 2" panel of Roxul 60 since I already have sheets of it. Right now, I think my only option is wood frame, backer board, Z bars with spacers. I could also make a wood french cleat, did you find those easier than using a z bar type solution?


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## Mpoes12

grendelrt said:


> Thanks for the reply, yeah I am doing a 2" panel of Roxul 60 since I already have sheets of it. Right now, I think my only option is wood frame, backer board, Z bars with spacers. I could also make a wood french cleat, did you find those easier than using a z bar type solution?



Not easier. I was being lazy. I had wood and I didn't have zbar. You could give it a try, it's possible that the wood would work better, I've never bothered to experiment. 

I have always found this approach limiting. It's very difficult to mount something that covers most of an area of the ceiling because it needs room to slide into place. 

I will be mounting some corner bass trap soffits that I plan to build and was intending to use zbar or a similar cleat. It will run the length of the room so if that works out I'll be sure to take picture of how I did it. I'm looking at other mounting options as well though. 


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## dnoonie

grendelrt said:


> For anyone who has made acoustic panels for their ceiling, I am looking for some examples of a good build. I ran into issues mounting mine with Z clips due to how close the tolerance is on them. I am probably going back to the drawing board and making a couple new panels, but looking for ideas on how to make them to facilitate easy mounting. Currently I am thinking a 1x2 + quater round frame, then adding a spacer below each z clip on the ceiling and panel to give a little extra tolerance. I think doing a fabric wrapped frameless panel with a drywall holder directly into the roxul would be the easiest, but I don't think it would hold up over time. So any one who has done ceiling panels, preferably flush against the ceiling or close to it, please share your build =) Thanks!!


I've hung my ceiling panels with hooks and eyes connected with zip ties. My wall panels are all hung on a 1" plywood mounting strip, it gives me a good plenum, is more secure since the mounting strip is attached to studs and puts fewer holes in the wall.

Cheers,


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## roxiedog13

*acoutic treatment suggestions*

So, I'm just starting a new theater want to incorporate acoustic material into the build in-wall as apposed to on wall panels .

The room will be 16 X 28 ft but it's a loft room with low side walls starting at 4ft rising to 12 ft . What I was thinking about doing
is when I stud out the side walls , the screen wall and rear I would add rigid Roxul soundproofing insulation everywhere . This room
is going to be a virtual velvet black pit . Will cover everything with with Joanne Royalty Black velvet, essentially making a 100% structural
acoustic box.

Is this overkill ? I'm on the same floor as our main bedroom separated by a hallway, I'm trying to ensure the sound is also contained . The one internal 
wall towards the bedroom will be sound proofed including a full double wall , all other walls are exterior, less of a concern .

Opinions and suggestions please .


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## LydMekk

I am sure others will chime in but: no point in only soundproofing that one wall separating the theatre from the bedroom.
The sound and noise will travel via flanking, e.g. go into the roof trusses and transplant into the rest of the ceiling, bypassing your internal wall divider, also transport via the floor.
You need to make a box inside the cinema which will be soundproofed on all sides if this is supposed to work, floor, ceilings, walls.


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## OKGeek

roxiedog13 said:


> So, I'm just starting a new theater want to incorporate acoustic material into the build in-wall as apposed to on wall panels .
> 
> The room will be 16 X 28 ft but it's a loft room with low side walls starting at 4ft rising to 12 ft . What I was thinking about doing
> is when I stud out the side walls , the screen wall and rear I would add rigid Roxul soundproofing insulation everywhere . This room
> is going to be a virtual velvet black pit . Will cover everything with with Joanne Royalty Black velvet, essentially making a 100% structural
> acoustic box.
> 
> Is this overkill ? I'm on the same floor as our main bedroom separated by a hallway, I'm trying to ensure the sound is also contained . The one internal
> wall towards the bedroom will be sound proofed including a full double wall , all other walls are exterior, less of a concern .
> 
> Opinions and suggestions please .


With such amount of absorption, you may end up with quite an anechoic room, which is for sure not pleasant to be in. One simply shall not overttreat the room.

In addition to that, so much inwall absorption covered with fabric will absorb lots of high and mid range, while less LF (depends on the thickness of absorption of course). This, before putting velvet on top you're better to measure decay times and may be cover some of the treatment with plastic before velvet, so to capture more LF, than HF.

Please find my post and few following answers in that regard, which were posted in this thread recently

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## roxiedog13

LydMekk said:


> I am sure others will chime in but: no point in only soundproofing that one wall separating the theatre from the bedroom.
> The sound and noise will travel via flanking, e.g. go into the roof trusses and transplant into the rest of the ceiling, bypassing your internal wall divider, also transport via the floor.
> You need to make a box inside the cinema which will be soundproofed on all sides if this is supposed to work, floor, ceilings, walls.


My gut feeling was the same actually , was hoping not to have this confirmed . I'll just have to put as much mass as possible in the floor and ceiling, add all the soundproofing I can inside
and hop for the best. My wife is a sound sleeper too and has not complained thus far.  My current theater is in the basement, bedroom on the second floor however the air exchanger ducting is 
a horrible conduit for sound, forget the base. Memory foam bed and pillows will help my cause. Thanks!


----------



## Mpoes12

roxiedog13 said:


> My gut feeling was the same actually , was hoping not to have this confirmed . I'll just have to put as much mass as possible in the floor and ceiling, add all the soundproofing I can inside
> and hop for the best. My wife is a sound sleeper too and has not complained thus far.  My current theater is in the basement, bedroom on the second floor however the air exchanger ducting is
> a horrible conduit for sound, forget the base. Memory foam bed and pillows will help my cause. Thanks!




Soundproofing and acoustic absorption are not the same. This really is better for the other thread. If you don't fully soundproof the room properly you won't have the results you need. 

It's not all about the mass. A large solid surface can readily transfer sound. Yes more mass is harder to move but even a cement slab transmits sound, it's one of the major sound conduits in commercial spaces and basements. 

I would say that you will want to address the hvac. That can end up working just like two cups and a string. It will readily transmit sound as if nothing is stopping it. In my basement I can whisper into the duct and hear it clearly in an upstairs bathroom two floors above. My theater is on the exact same main branch, yet 100dbs in the theater is not heard much at either of those ducts. I'm finding certain frequencies still travel audibly, but at a very reduced level. 



Sent from my iPhone with a keyboard that predicts what I mean very poorly


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## Mpoes12

roxiedog13 said:


> So, I'm just starting a new theater want to incorporate acoustic material into the build in-wall as apposed to on wall panels .
> 
> The room will be 16 X 28 ft but it's a loft room with low side walls starting at 4ft rising to 12 ft . What I was thinking about doing
> is when I stud out the side walls , the screen wall and rear I would add rigid Roxul soundproofing insulation everywhere . This room
> is going to be a virtual velvet black pit . Will cover everything with with Joanne Royalty Black velvet, essentially making a 100% structural
> acoustic box.
> 
> Is this overkill ? I'm on the same floor as our main bedroom separated by a hallway, I'm trying to ensure the sound is also contained . The one internal
> wall towards the bedroom will be sound proofed including a full double wall , all other walls are exterior, less of a concern .
> 
> Opinions and suggestions please .



For acoustics you will want to add the treatment to the shell. You mention soundproofing which I mentioned earlier is a separate issue. If you need soundproofing then you must address that first. Your plan would make the room less sound isolated than a normal room as you would have less drywall. 

As for acoustics, you can actually frame the outer shell with 2x4's, line the spaces with roxul, and cover in velvet. It will likely provide too much absorption but you can actually address this. Studios are built this way frequently. You first build a soundproof shell. You then frame over the shell with material that ranges from 4" to 24" thick. You then layer in materials for acoustic purposes in different areas. For example the rear wall is typically framed out about 24" and a first layer of MLV is hung spaced about an inch from the wall. Then hanger traps or solid acoustic insulation is stuffed in front of the MLV out to the 24" end of the framing. That is then covered in fabric. To reduce HF absorption the outer side will be covered in wood diffusers or strips of wood. You could also cover the Fiberglass with plastic membranes to reflect some sound. 

In other words if you plan it you can make a great room that way, but I'm not sure that is what you had in mind. 


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## roxiedog13

Mpoes12 said:


> Soundproofing and acoustic absorption are not the same. This really is better for the other thread. If you don't fully soundproof the room properly you won't have the results you need.
> 
> It's not all about the mass. A large solid surface can readily transfer sound. Yes more mass is harder to move but even a cement slab transmits sound, it's one of the major sound conduits in commercial spaces and basements.
> 
> I would say that you will want to address the hvac. That can end up working just like two cups and a string. It will readily transmit sound as if nothing is stopping it. In my basement I can whisper into the duct and hear it clearly in an upstairs bathroom two floors above. My theater is on the exact same main branch, yet 100dbs in the theater is not heard much at either of those ducts. I'm finding certain frequencies still travel audibly, but at a very reduced level.
> 
> 
> 
> Sent from my iPhone with a keyboard that predicts what I mean very poorly



Ducting is in the current home, I'm building a new home, will not have connected ducting, that was my point . I was just saying my poor wife has been putting
up with my theater for years 2 floors away thanks to ducting. The new build will not have this guaranteed. Apparently using soft insulation ducting works like
a muffler in a car, unfortunately mine was all tin and not accessible to modify .


I know soundproofing and acoustic is not the same, I posted this in both threads actually to get some feedback on both .


----------



## roxiedog13

Mpoes12 said:


> For acoustics you will want to add the treatment to the shell. You mention soundproofing which I mentioned earlier is a separate issue. If you need soundproofing then you must address that first. Your plan would make the room less sound isolated than a normal room as you would have less drywall.
> 
> As for acoustics, you can actually frame the outer shell with 2x4's, line the spaces with roxul, and cover in velvet. It will likely provide too much absorption but you can actually address this. Studios are built this way frequently. You first build a soundproof shell. You then frame over the shell with material that ranges from 4" to 24" thick. You then layer in materials for acoustic purposes in different areas. For example the rear wall is typically framed out about 24" and a first layer of MLV is hung spaced about an inch from the wall. Then hanger traps or solid acoustic insulation is stuffed in front of the MLV out to the 24" end of the framing. That is then covered in fabric. To reduce HF absorption the outer side will be covered in wood diffusers or strips of wood. You could also cover the Fiberglass with plastic membranes to reflect some sound.
> 
> In other words if you plan it you can make a great room that way, but I'm not sure that is what you had in mind.
> 
> 
> Sent from my iPhone with a keyboard that predicts what I mean very poorly



Thanks for the input again actually, and yes this is exactly what I'm going for . As others mentioned I need to soundproof the room to prevent sound traveling through the 
roof rafters and joists that connect to the adjacent bedroom. The theater will be in a second floor loft above a garage. At the other end of this second floor will be a full 
master ensuite bedroom separated by a staircase hall . Actually the bedroom will be furthest away, before that a large walk-in closet one side, large ensuite bathroom the other.
If I do this right I should be able to keep the noise from travelling back to the bedroom area, at least to a minimum. 


Soundproof the room and then add second wall for acoustic, possibly even adding reflective surfaces to accentuate the correct frequencies as necessary .


----------



## Mpoes12

roxiedog13 said:


> Thanks for the input again actually, and yes this is exactly what I'm going for . As others mentioned I need to soundproof the room to prevent sound traveling through the
> roof rafters and joists that connect to the adjacent bedroom. The theater will be in a second floor loft above a garage. At the other end of this second floor will be a full
> master ensuite bedroom separated by a staircase hall . Actually the bedroom will be furthest away, before that a large walk-in closet one side, large ensuite bathroom the other.
> If I do this right I should be able to keep the noise from travelling back to the bedroom area, at least to a minimum.
> 
> 
> Soundproof the room and then add second wall for acoustic, possibly even adding reflective surfaces to accentuate the correct frequencies as necessary .



Do you feel comfortable that you know how to mix materials and surfaces. It's too hard to give general advice here but if you have more room details and specific questions I can try to answer. 

Again I'll mention that I suggest you post the soundproofing bit in the other thread to keep the topics separate. It sounds like you plan to just soundproof the floor and ceiling? If so I think you are missing a lot of important flanking paths. It certainly won't be for nothing but sound can travel through walls, up through the ceiling into the common attic space and into other places. It can travel into the floor. It can also travel through the walls. Being over a garage helps but just doing floor and ceiling probably isn't enough. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


----------



## roxiedog13

Mpoes12 said:


> Do you feel comfortable that you know how to mix materials and surfaces. It's too hard to give general advice here but if you have more room details and specific questions I can try to answer.
> 
> Again I'll mention that I suggest you post the soundproofing bit in the other thread to keep the topics separate. It sounds like you plan to just soundproof the floor and ceiling? If so I think you are missing a lot of important flanking paths. It certainly won't be for nothing but sound can travel through walls, up through the ceiling into the common attic space and into other places. It can travel into the floor. It can also travel through the walls. Being over a garage helps but just doing floor and ceiling probably isn't enough.
> 
> 
> Sent from my iPhone with a keyboard that predicts what I mean very poorly



My plan was to encapsulate the entire room with roxul rigid sound absorbing material , and soundproof additionally . 


To answer your first question I am not experienced in acoustic materials application nor am I completely up on sound proofing. That being said I do have a very 
good understanding of all the variables and materials, just want to ensure I will not over or under design the materials and application necessary . 


My first theater ended up reasonably well with the acoustic materials and panels I made, this theater is a new build .


Is this a hobby for you or do you design professionally ? I certainly appreciate all the help and advise , just want to ensure I'm not 
imposing if I do ask for suggestions .


----------



## VideoGrabber

roxiedog13 said:


> What I was thinking about doing is when I stud out the side walls , the screen wall and rear I would add rigid Roxul soundproofing insulation everywhere . This room
> is going to be a virtual velvet black pit . Will cover everything with with Joanne Royalty Black velvet, essentially making a 100% structural acoustic box.
> 
> Is this overkill?


In my opinion, yes, that would be far too much absorption. The room will be overly dead, with no high end, and no reverberant field.

While you certainly could then counteract some of that with reflective materials placed under your velvet (assuming that material was acoustically transparent, which it may not be), I think it makes sense to begin by asking how much of the surface area should be absorbent, vs. diffusive, vs. reflective. Then you know what to start with as your default surface material. The largest of those 3 would be reflective, so why start by eliminating that, then trying to add it back in again? Seems counterproductive to me. Unless you're planning to rely on the Roxul for it's thermal insulating properties as well?


----------



## Mpoes12

roxiedog13 said:


> My plan was to encapsulate the entire room with roxul rigid sound absorbing material , and soundproof additionally .
> 
> 
> To answer your first question I am not experienced in acoustic materials application nor am I completely up on sound proofing. That being said I do have a very
> good understanding of all the variables and materials, just want to ensure I will not over or under design the materials and application necessary .
> 
> 
> My first theater ended up reasonably well with the acoustic materials and panels I made, this theater is a new build .
> 
> 
> Is this a hobby for you or do you design professionally ? I certainly appreciate all the help and advise , just want to ensure I'm not
> imposing if I do ask for suggestions .



How do you plan to soundproof?

You don't need to use rigid roxul in the walls. That would be a waste of money. I suggest something much cheaper. In the walls you are just damping resonances so any insulation is equally effective. There is little if any advantage to roxul rigid insulation. Even Safe n' sound isn't really needed, but if it's in your budget it certainly won't hurt. 

I consult on acoustics on the side. It is not my main job. I wouldn't be here answering questions if I wasn't willing to. At least so far this side business has been sporadic and commercial. I don't give advice on the forums so that I can sell people services or products. There are others on the forums better equipped to do that. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


----------



## roxiedog13

VideoGrabber said:


> In my opinion, yes, that would be far too much absorption. The room will be overly dead, with no high end, and no reverberant field.
> 
> While you certainly could then counteract some of that with reflective materials placed under your velvet (assuming that material was acoustically transparent, which it may not be), I think it makes sense to begin by asking how much of the surface area should be absorbent, vs. diffusive, vs. reflective. Then you know what to start with as your default surface material. The largest of those 3 would be reflective, so why start by eliminating that, then trying to add it back in again? Seems counterproductive to me. Unless you're planning to rely on the Roxul for it's thermal insulating properties as well?



Thanks for the reply . Well, I do live in Canada, more insulation is always good.  


Actually, the exterior side walls , floor and the screen end wall will be insulated already with R40 . Only the center interior wall will not be insulated already, I plan to use
a double wall and plenty of insulation there as the other end of this second story is our main bedroom separated by a hallway . 


Within the theater loft ( sloped and vaulted ceiling) I have to build a knee wall on the sides . I'm going to frame out the sides and end, add Roxul between the studs in about
1/3rd of the spaces leave the rest. I will be able to add or remove easily because the covering will just be velvet panels attached with Velcro strips . Once I'm moved in and all furniture in place, the carpet, stage and speakers , fixtures and so on, THEN I'll fire up the REW ( room EQ wizard ) https://www.roomeqwizard.com/ see how it looks . 


I'm more concerned about sound travelling back the floor or through the roof at this point , that's what I have to concentrate on . Within the theater I will have the ability
to add or remove reflective or absorption panels to balance things out.


----------



## VideoGrabber

roxiedog13 said:


> I'm going to frame out the sides and end, add Roxul between the studs in about 1/3rd of the spaces leave the rest. I will be able to add or remove easily because the covering will just be velvet panels attached with Velcro strips.


That is a reasonable way to proceed. 1/3 absorption will be much closer to what you wind up needing than 100%. I would simply echo Mpoes when he said that you really don't need Roxul for that. Any inexpensive absorber would work as well, in those locations. Roxul is great because they are semi-rigid formed panels, in a convenient size, and you can easily cover and hang them, etc. But as you are planning, you could also easily move them around, w/o having to deal with nasties like fiberglass fibers. So their reconfigurability may still have some benefit for you, that would justify the additional cost.

My only possible caution would be to make sure that the velvet you plan to cover things with is actually acoustically transparent. Not all are. To the extent the velvet material either absorbs or reflects, it won't make any difference what you have behind it.



> Once I'm moved in and all furniture in place, the carpet, stage and speakers , fixtures and so on, THEN I'll fire up the REW ( room EQ wizard ) https://www.roomeqwizard.com/ see how it looks.


That sounds like a wise plan. Knowing is always better than guessing. 

There is one other opportunity that may be somewhat uniquely available to you, with your plan to essentially be skinning a completely open-framed set of studs. You may be able to mount/suspend some drywall pieces in sections/slices, in such a way that each panel can still move. I.e., is resilient, and not rigidly attached to the studs. This can be an effective way to help tame lower bass resonant frequencies, though it's not often employed outside custom-designed spaces. 

Unfortunately, I have no expertise in this area, but wanted to make you aware of it. I think Geddes was a proponent of that methodology (wall loading), so perhaps others here may be able to comment on this.


----------



## roxiedog13

VideoGrabber said:


> That is a reasonable way to proceed. 1/3 absorption will be much closer to what you wind up needing than 100%. I would simply echo Mpoes when he said that you really don't need Roxul for that. Any inexpensive absorber would work as well, in those locations. Roxul is great because they are semi-rigid formed panels, in a convenient size, and you can easily cover and hang them, etc. But as you are planning, you could also easily move them around, w/o having to deal with nasties like fiberglass fibers. So their reconfigurability may still have some benefit for you, that would justify the additional cost.
> 
> My only possible caution would be to make sure that the velvet you plan to cover things with is actually acoustically transparent. Not all are. To the extent the velvet material either absorbs or reflects, it won't make any difference what you have behind it.
> 
> 
> 
> That sounds like a wise plan. Knowing is always better than guessing.
> 
> There is one other opportunity that may be somewhat uniquely available to you, with your plan to essentially be skinning a completely open-framed set of studs. You may be able to mount/suspend some drywall pieces in sections/slices, in such a way that each panel can still move. I.e., is resilient, and not rigidly attached to the studs. This can be an effective way to help tame lower bass resonant frequencies, though it's not often employed outside custom-designed spaces.
> 
> Unfortunately, I have no expertise in this area, but wanted to make you aware of it. I think Geddes was a proponent of that methodology (wall loading), so perhaps others here may be able to comment on this.


Thank you for the reply 

I had to read a few times to understand . What you are saying is essentially, make a gyproc drum from the framing such that you leave a large section of the normal framing out . The attached gyproc will resonate/absorb the low frequencies. 
When you said suspend at first I envisioned free hanging pieces but I believe you meant what I said . I like this concept better, gives some rigidity to the walls behind the black velvet. On the sloped part of the ceiling I could use the 
gyproc on frame , roxul or a combo. Now I have to check the black velvet , see what the acoustic characteristics of that are . Next stop the black theater thread .


----------



## roxiedog13

Mpoes12 said:


> How do you plan to soundproof?
> 
> You don't need to use rigid roxul in the walls. That would be a waste of money. I suggest something much cheaper. In the walls you are just damping resonances so any insulation is equally effective. There is little if any advantage to roxul rigid insulation. Even Safe n' sound isn't really needed, but if it's in your budget it certainly won't hurt.
> 
> I consult on acoustics on the side. It is not my main job. I wouldn't be here answering questions if I wasn't willing to. At least so far this side business has been sporadic and commercial. I don't give advice on the forums so that I can sell people services or products. There are others on the forums better equipped to do that.
> 
> 
> Sent from my iPhone with a keyboard that predicts what I mean very poorly


Appreciate the feedback

I mentioned in a previous post , couple back what I will do to insulate the home, inside the theater . I will have to add some 4-5' knee walls ,can add acoustic or reflective material within those walls rather than wall mounting acoustic panels . I mentiioned
the trade name Roxul which is generic for insulation from acoustic to fireproofing and just plain old thermal material . Basically, I will use what ever is necessary to make the room acoustically correct , in the process will try to keep the materials within the new build walls instead of hanging panels afterwards . 

Maybe we could go to PM for discussion on consult , would rather compensate someone and get the right job done correct as long as you are confident you can do this properly .


----------



## [email protected]

Building a dedicated HT in the basement and need a little advice. Here's my general setup:

Room: 25' by 15'
Two rows at 13' and 19' from the screen. Back row up on a 16" riser.
Wired for Atmos 7.2.6 though I will probably only be able to afford an AVR that supports 7.2.4. TBD.
Three identical LCRs and two subs on a stage (10" high???) behind an AT screen within a false screen wall. (Layout of the room attached in an image.)
LCR - Klipsch RP-260F
Subs - TBD
Sides - Klipsch R 5650 S
Rear - Klipsch RP 160M
Atmos in-ceiling - Klipsch CDT-5650 C II


Done a lot of research and know I simply can't afford to do full scale sound proofing nor acoustical treatments. i.e, not doing 2-layer drywall, clips or rails.
But I do plan on doing base traps, floor to ceiling treatments on the front wall behind the speakers, and acoustic panels on the side walls as needed in the theater.

Question: Everyone seems to advocate using either 1"-2" rigid fiberglass boards or 1"-2" Linacoustic Duct Liner to completely cover the front wall behind the speakers. Duct Liner is very expensive. Rigid fiberglass is less but still expensive. Since I want that wall black and will have to cover the insulation with black AT fabric anyway, could I get the same results using Roxul Safe n Sound? I believe the biggest problem would be attaching the Safe n Sound to the wall but if I put it in frames and cover it in AT material (just like the panels I plan on making) wouldn't that work? I'm basing this off a chart I found showing Safe n Sound to be just as good but you all are the experts and I'm looking to you for advice.....

Floor to Ceiling Roxul Safe n Sound panels on the front wall or do I really need the Linacoustic or rigid fiberglass board solution?


----------



## Mpoes12

[email protected] said:


> Building a dedicated HT in the basement and need a little advice. Here's my general setup:
> 
> 
> 
> Room: 25' by 15'
> 
> Two rows at 13' and 19' from the screen. Back row up on a 16" riser.
> 
> Wired for Atmos 7.2.6 though I will probably only be able to afford an AVR that supports 7.2.4. TBD.
> 
> Three identical LCRs and two subs on a stage (10" high???) behind an AT screen within a false screen wall. (Layout of the room attached in an image.)
> 
> LCR - Klipsch RP-260F
> 
> Subs - TBD
> 
> Sides - Klipsch R 5650 S
> 
> Rear - Klipsch RP 160M
> 
> Atmos in-ceiling - Klipsch CDT-5650 C II
> 
> 
> 
> 
> 
> Done a lot of research and know I simply can't afford to do full scale sound proofing nor acoustical treatments. i.e, not doing 2-layer drywall, clips or rails.
> 
> But I do plan on doing base traps, floor to ceiling treatments on the front wall behind the speakers, and acoustic panels on the side walls as needed in the theater.
> 
> 
> 
> Question: Everyone seems to advocate using either 1"-2" rigid fiberglass boards or 1"-2" Linacoustic Duct Liner to completely cover the front wall behind the speakers. Duct Liner is very expensive. Rigid fiberglass is less but still expensive. Since I want that wall black and will have to cover the insulation with black AT fabric anyway, could I get the same results using Roxul Safe n Sound? I believe the biggest problem would be attaching the Safe n Sound to the wall but if I put it in frames and cover it in AT material (just like the panels I plan on making) wouldn't that work? I'm basing this off a chart I found showing Safe n Sound to be just as good but you all are the experts and I'm looking to you for advice.....
> 
> 
> 
> Floor to Ceiling Roxul Safe n Sound panels on the front wall or do I really need the Linacoustic or rigid fiberglass board solution?




There will be no difference between duct liner and using rigid fiberglass. Safe and sound might sacrifice a little LF absorption but for all practical purposes also no different. 

You might look into some black tyvek. It’s used for ground drains and as weed cloth so can be bought in large rolls. It helps keep the fibers in and is about as black as it gets. It also would act like a LF membrane. It is gas permeable but would be somewhat reflective at higher frequencies (which would be a good thing here). 

I recently bought some 4” 6lb density mineral wool at Menards for something like $40. 









It’s a great value. It’s equal to the roxul __60 products. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


----------



## Mpoes12

[email protected] said:


> Building a dedicated HT in the basement and need a little advice. Here's my general setup:
> 
> 
> 
> Room: 25' by 15'
> 
> Two rows at 13' and 19' from the screen. Back row up on a 16" riser.
> 
> Wired for Atmos 7.2.6 though I will probably only be able to afford an AVR that supports 7.2.4. TBD.
> 
> Three identical LCRs and two subs on a stage (10" high???) behind an AT screen within a false screen wall. (Layout of the room attached in an image.)
> 
> LCR - Klipsch RP-260F
> 
> Subs - TBD
> 
> Sides - Klipsch R 5650 S
> 
> Rear - Klipsch RP 160M
> 
> Atmos in-ceiling - Klipsch CDT-5650 C II
> 
> 
> 
> 
> 
> Done a lot of research and know I simply can't afford to do full scale sound proofing nor acoustical treatments. i.e, not doing 2-layer drywall, clips or rails.
> 
> But I do plan on doing base traps, floor to ceiling treatments on the front wall behind the speakers, and acoustic panels on the side walls as needed in the theater.
> 
> 
> 
> Question: Everyone seems to advocate using either 1"-2" rigid fiberglass boards or 1"-2" Linacoustic Duct Liner to completely cover the front wall behind the speakers. Duct Liner is very expensive. Rigid fiberglass is less but still expensive. Since I want that wall black and will have to cover the insulation with black AT fabric anyway, could I get the same results using Roxul Safe n Sound? I believe the biggest problem would be attaching the Safe n Sound to the wall but if I put it in frames and cover it in AT material (just like the panels I plan on making) wouldn't that work? I'm basing this off a chart I found showing Safe n Sound to be just as good but you all are the experts and I'm looking to you for advice.....
> 
> 
> 
> Floor to Ceiling Roxul Safe n Sound panels on the front wall or do I really need the Linacoustic or rigid fiberglass board solution?




There will be no difference between duct liner and using rigid fiberglass. Safe and sound might sacrifice a little LF absorption but for all practical purposes also no different. 

You might look into some black tyvek. It’s used for ground drains and as weed cloth so can be bought in large rolls. It helps keep the fibers in and is about as black as it gets. It also would act like a LF membrane. It is gas permeable but would be somewhat reflective at higher frequencies (which would be a good thing here). 

I recently bought some 4” 6lb density mineral wool at Menards for something like $40. 









It’s a great value. It’s equal to the roxul __60 products. 


Sent from my iPhone with a keyboard that predicts what I mean very poorly


----------



## Solarium

Deleted (created thread for this)


----------



## LydMekk

Will this be efficient mounted on the back of the ceiling for diffusion purposes?
EPS. The surface will be hard enough to scatter sound. This is not soft foam.
Wood will be very heavy for mounting on the drywall plates on my ceiling.
The front half of the ceiling "island" (4m width of a total of 7m ceiling width) will be absorbers, the back half this stuff.


----------



## erwinfrombelgium

Yeah right! So if the companies that sell this stuff tell you it's effective, it must be right? Mmm... The effect of EPS is still absorption, not diffusion.

What I have done is diffusion sidewalls and absorption ceiling. Sounds good with the outdoor speakers I used for testing.


----------



## [email protected]

I've been googleing Home Theaters Design and seen some really nice fabric for acoustic panels. I wan't to make my own since I figure I can make 3-4 myself for the price of buying one premade. 

When I go to where everyone tells me to go for fabric, (GOM, Acousticalsolutions, acousticsonic, etc) they don't have anything nearly this decorative. (See attached figures) Is it that the people who use this decorative material are oblivious and just using material that isn't acousticaly transparent? Or are they getting their fabric from somewhere I haven't found yet? Any ideas where I can get something like this in an acousticly transparent material so I can build my own panels?


----------



## nirvana_av

[email protected] said:


> I've been googleing Home Theaters Design and seen some really nice fabric for acoustic panels. I wan't to make my own since I figure I can make 3-4 myself for the price of buying one premade.
> 
> When I go to where everyone tells me to go for fabric, (GOM, Acousticalsolutions, acousticsonic, etc) they don't have anything nearly this decorative. (See attached figures) Is it that the people who use this decorative material are oblivious and just using material that isn't acousticaly transparent? Or are they getting their fabric from somewhere I haven't found yet? Any ideas where I can get something like this in an acousticly transparent material so I can build my own panels?


It isn't a matter of acoustically transparent. Practically all indoor fabrics are acoustically transparent. It's an issue of being fire retardant. You can use any fabric, but steps would need to be taken to apply some type of fire retardant.


----------



## [email protected]

nirvana_av said:


> It isn't a matter of acoustically transparent. Practically all indoor fabrics are acoustically transparent. It's an issue of being fire retardant. You can use any fabric, but steps would need to be taken to apply some type of fire retardant.


Any ideas where I can get some of this beautiful fabric like those shown in the post above?


----------



## Gearpro

I have a 27x20x8 room with cathedral ceilings that go up to 12'.
I was thinking of getting GIK 6" alpha absorbers/diffusers for my rooms 1st reflection locations and possible 2nd order reflection spots. I was still reading and trying to learn..
I see that they have their polyfusors on Black Friday sale for 15% off so was wondering if anyone has used them or has some advice about them vs the alpha series. 
Thanks


Sent from my iPhone using Tapatalk


----------



## alextr75

I have about 6 DIY 2 x 4 acoustic panels, from a wooden frame and 3" safe'n'sound.

I was wondering whether it is worth investing into upgrading / replacing these to get some more effect at lower frequencies, e.g. serve as bass traps too.

I can't find yet 703 here in Canada, tried to look for Roxul's Rockboard that was recommended somewhere, but can't yet find any near my location. What I found is something called CavityRock , also made by Roxul, or maybe I can just stack 2 of 3" Safe'n'Sound panels together and that would be enough ? Obviously I'd need to build a new frame either way.

I am hoping to have this as broadband, so help with higher frequencies too.

Assuming I am stacking two 3" panels together, would you think there would much difference between these 3 options ?

These are the specs for density and acoustical performance ASTM C423

3" Safe'n'Sound - 2.5 lb/ft³
125 Hz - 0.52
250 Hz - 0.96
500 Hz - 1.18
1000 Hz - 1.07
2000Hz - 1.05 
4000 Hz - 1.05
NRC - 1.05

3" Rockboard 40/60 - 4 lb/ft³ / 6 lb/ft³ 
125 Hz - 0.63
250 Hz - 0.95
500 Hz - 1.14
1000 Hz - 1.01
2000Hz - 1.03
4000 Hz - 1.04
NRC - 1.05

3" Cavity Rock - it is dual layer, outer 6.2 lbs/ft³ , inner 4.1 lbs/ft³
125 Hz - 0.72
250 Hz - 0.93
500 Hz - 0.88
1000 Hz - 0.84
2000Hz - 0.9
4000 Hz - 0.97
NRC - 0.9

I am planning on using two 3" panels stacked together.

Given I can only find Safe'n'Sound and Cavity Rock maybe safer to stick with just Safe'n'Sound ?

I am not really sure how to interpret the differences in performance and whether they are big, but seems like Safe'n'Sound generally is better here, where the Cavity Rock only has some advantage @ 125 Hz, and is also denser. Mind you, it is lower frequencies that I want to improve, so the 125Hz may be important, but not sure how much of a difference it is between 0.72 and 0.52, and whether it is worth losing performance over the rest of the frequency span.


----------



## OKGeek

Alex, hi



alextr75 said:


> I was wondering whether it is worth investing into upgrading / replacing these to get some more effect at lower frequencies, e.g. serve as bass traps too.
> 
> Assuming I am stacking two 3" panels together, would you think there would much difference between these 3 options ?


It depends on the placements, available to you. 6'' panels of broadband absorbers might not be the best strategy, as different frequencies shall be treated in different places of the room:

1) Corner bass traps will give you better results for LF, as bass builds up along the room boundaries and then congregate in the corners. At the same time flat panels on the wall behind the MLP (and other points of first reflections, if possible) are better for mid and high frequencies, so to avoid comb filtering.

2) Normally you don't need 6''+ thick panel for mid- and high- frequencies absorption and 3'' panels, which you already have, shall work just fine

3) LF though requires thicker absorber for sure, but you can "cheat" and use air gap instead of extra layer. You can try to mount existing panels with 2-3'' air gap behind and see if there is any improvement in LF ringing, before spending extra cash and time to redo the panels. I would also put them straddled across the corners to see what the impact on reverberation time in LF range is now.



alextr75 said:


> I am not really sure how to interpret the differences in performance and whether they are big, but seems like Safe'n'Sound generally is better here, where the Cavity Rock only has some advantage @ 125 Hz, and is also denser. Mind you, it is lower frequencies that I want to improve, so the 125Hz may be important, but not sure how much of a difference it is between 0.72 and 0.52, and whether it is worth losing performance over the rest of the frequency span.


1) numbers you have on materials don't tell you the whole story, as it's below-100hz range where significant LF frequency ringing occurs, which you want to decrease and materials may have different roll-offs in absorption below posted 125Hz

2) Assuming both materials have comparable roll of I would take Cavity Rock as it absorbs almost 50% more in LF being almost on par in the mid range (less than 15% diff)

I also found articles by @Ethan Winer are very informative in respect of acoustical treatments


----------



## alextr75

Thanks for the reply. I actually also have about 24 12x12x2" foam pyramid panels I just got from Amazon initially thinking to replace my DIY panels because was getting complaints from wife about the ugly looks, but when I got them and realized how thin and small they looked, I was on the verge of returning them and just putting back my DIY panels.

I wonder now if maybe I should use the foam ones for mid and high, replacing the big ones where they used to hang on the walls, and put my big DIY in the corners, maybe even stack two together if results are better.

Though honestly that foam just doesn't look like it can do much. I just watched a guy on YouTube putting some artistic patterns on the wall with foam panels, and at the end of the video while he was talking about results etc .., I could still hear tons of echo, so seriously makes me question their effectiveness, where I know my DIY panels were very effective in taming down the noise in the room.

Something else I am also wondering about is the big 72" wide opening I have towards the hallway (with laminated flooring) and rest of the house . I have read this openings tend to work like bass traps already so with that not sure if adding more bass traps in the room it self will help. On the other hand I was also hoping to put a double door there to somewhat soundproof the room and do not disturb the family as much when watching movies, and to hopefully also help with the bass pressurization in the room. But at this point I am not sure if putting in a door in there will actually be worse of better for the bass, since keeping it open acts as a bass trap, but keeping it close will help pressurization. I guess the only way to know is to put one in, and measure results in REW with one open and one close to see what works better .. only downside is by that time I would have already paid for and installed it


----------



## asarose247

Anyone read or have any experience with this issue

Comparison for light absorption between 

Royalty Velvet #3 black

and Duvetyne 12oz. black ( from Chicagocanvas.com) , known for light mitigation wrt to off angle "flaring"

price differences at this time are negligible 

I want to cut down on a "halo" effect that bugs me as it radiates from the TV (65" LG 4K, HDR) in a room that otherwise can be made about 99% blacked out. Viewing distance is just under 7'.

AT properties at this time not a consideration.

It's my understanding that the velvet is acceptably (YMMV) AT.

TY


----------



## asarose247

Anyone read or have any experience with this issue

Comparison for light absorption between 

Royalty Velvet #3 black

and Duvetyne 12oz. black ( from Chicagocanvas.com) , known for light mitigation wrt to off angle "flaring"

price differences at this time are negligible 

I want to cut down on a "halo" effect that bugs me as it radiates from the TV (65" LG 4K, HDR) in a room that otherwise can be made about 99% blacked out. Viewing distance is just under 7'.

AT properties at this time not a consideration.

It's my understanding that the velvet is acceptably (YMMV) AT.

TY


----------



## STAIN0

Could someone please advise me if these would be any good to use in diy sound absorption panels?
Also possibly stacking them in triangle corner bass traps?

https://insulation.com.au/product/fi48-rigid-glasswool-sheets-acoustic-blanket/
https://www.pricewiseinsulation.com.au/product/50mm-hd-acoustic-panels-plain-black/

Thanks in advance.


----------



## OKGeek

alextr75 said:


> I wonder now if maybe I should use the foam ones for mid and high, replacing the big ones where they used to hang on the walls, and put my big DIY in the corners, maybe even stack two together if results are better.


Without actual measurements, it looks like you're entering guessing zone without figuring out what really happens in your room and how hard you need to treat the walls. Maybe foam will work just fine or may be all panels you have are just not enough.

I would recommend to go measurements (REW + UMIK-1 is one of the safe option) before committing something on the wall or purchasing more absorption panels. You'll also be able to see if any of the panels you have really make in impact or just deliver placebo effect. It's RT60 and Impulse response which you after. 

On Impulse response for starter look through
Article from GIKAcoustic
and Manual part from REW

On RT60 
0.2 - 0.3 is good for mid- and -high
0.3 - 0.5 is OK for bass, while LFs are usually harder to treat 



alextr75 said:


> Something else I am also wondering about is the big 72" wide opening I have towards the hallway (with laminated flooring) and rest of the house . I have read this openings tend to work like bass traps already so with that not sure if adding more bass traps in the room it self will help. On the other hand I was also hoping to put a double door there to somewhat soundproof the room and do not disturb the family as much when watching movies, and to hopefully also help with the bass pressurization in the room. But at this point I am not sure if putting in a door in there will actually be worse of better for the bass, since keeping it open acts as a bass trap, but keeping it close will help pressurization. I guess the only way to know is to put one in, and measure results in REW with one open and one close to see what works better .. only downside is by that time I would have already paid for and installed it


1) Wide opening affects the highest frequency, where your room gain increase. If you notice it or not depends on the type (sealed/ported), FR of your subwoofer and the room dimensions. So introduction of the door might not give you desired pressurization, if for example your room is 5000+ ft3 and sub is ported.

2) Efficiency of the opening as the bass trap is questionable as it highly depends on how the LF sound waves are reflected after the opening and if they even come through that opening. Theoretically it may introduce some absorption effect, but I won't count on that. Anyway, start measuring and see what ringing time you have below 200Hz

3) There is a rule of thumb to determine if the sub "sees" other rooms through opening: if opening is less than 1/2 of wavelength of the highest frequency played by sub, then this opening is almost non-existent for LF.
In your case 72'' corresponds to 144'' wavelength, which is for 95Hz. So everything below that level shall act almost as if opening is not there

Hope it helps


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## FargateOne

message deleted


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## monty6400

My room is picture below, it is 8ft wide by 16ft deep by 7ft tall. I have a trio of HTM12's up front behind an AT Screen and will soon be adding dual subs that span the width of the front wall for the speakers to sit on. The whole front wall, 1ft of the sides and 1ft at the top is covered in 1.5" thick acoustic foam panels. The first and second reflection points are covered by 2x4 panels of 2.5" insulation covered in fabric. The room when clapped in still has a slight high pitched echoing sound. The back of the room is in a L shape and is fairly untreated. The MLP falls between where the L starts so from ear to ear the rear walls are about 2.5ft difference. Currently dialogue from the centre channel sounds more prominent/boomy in my left ear than right, and I assume this is because of the odd room shape. Can anyone advise what to do about this and also where to place extra treatment! Many thanks!


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## monty6400

monty6400 said:


> My room is picture below, it is 8ft wide by 16ft deep by 7ft tall. I have a trio of HTM12's up front behind an AT Screen and will soon be adding dual subs that span the width of the front wall for the speakers to sit on. The whole front wall, 1ft of the sides and 1ft at the top is covered in 1.5" thick acoustic foam panels. The first and second reflection points are covered by 2x4 panels of 2.5" insulation covered in fabric. The room when clapped in still has a slight high pitched echoing sound. The back of the room is in a L shape and is fairly untreated. The MLP falls between where the L starts so from ear to ear the rear walls are about 2.5ft difference. Currently dialogue from the centre channel sounds more prominent/boomy in my left ear than right, and I assume this is because of the odd room shape. Can anyone advise what to do about this and also where to place extra treatment! Many thanks!


Pictures:


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## LydMekk

"The back of the room is in a L shape and is fairly untreated. "
Yes, well 
Try some strategically placed absorbent panels back there, NOT foam.
Carpet?

More importantly, naked ceiling?


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## monty6400

LydMekk said:


> "The back of the room is in a L shape and is fairly untreated. "
> Yes, well
> Try some strategically placed absorbent panels back there, NOT foam.
> Carpet?
> 
> More importantly, naked ceiling?


Thanks for the reply, I'm not overly keen on the look of the fabric panels, how do you think 7.5cm thick (3" Acoustic foam would work compared to the 2" thick panels? I'm able to get the foam panels at a larger size for less money than 1 panel!


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## ereed

I don't know why people try to save money by purchasing foam panels when it doesn't even do that great of a job as other materials. No good sounding room has foam in their room!


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## monty6400

ereed said:


> I don't know why people try to save money by purchasing foam panels when it doesn't even do that great of a job as other materials. No good sounding room has foam in their room!


I'm not very clued up on acoustical treatments etc, but why wouldn't an extra inch of foam compared to fiberglass insulation for cheaper not work well? I've seen a few builds using thick foam acoustical panels? Cheers!


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## ereed

monty6400 said:


> I'm not very clued up on acoustical treatments etc, but why wouldn't an extra inch of foam compared to fiberglass insulation for cheaper not work well? I've seen a few builds using thick foam acoustical panels? Cheers!


Foam absorbs mostly high end (500hz and up) and do not do a good job absorbing down low. Also it would take twice as many foam panels to absorb as much as fewer fiberglass panels, not to mention the fiberglass absorbs below 500hz as well. 

Imagine this.....3 broadband panels on wall would absorb as much as 6+ foam panels of the same size also while absorbing much lower. If you used all foam panels, then you would need bass traps to even it out since foam absorbs mostly high frequencies. So while foam is cheaper per dollar in absorption you would spend more in long run getting your room sounding right with all foam vs good quality panels from places such as GIK, ATS, Real Traps, etc. It may cost more upfront, but you would save money in long run by doing it right. Not to mention you get free advice from GIK and others to help you decide what you need without over purchasing panels.


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## monty6400

ereed said:


> Foam absorbs mostly high end (500hz and up) and do not do a good job absorbing down low. Also it would take twice as many foam panels to absorb as much as fewer fiberglass panels, not to mention the fiberglass absorbs below 500hz as well.
> 
> Imagine this.....3 broadband panels on wall would absorb as much as 6+ foam panels of the same size also while absorbing much lower. If you used all foam panels, then you would need bass traps to even it out since foam absorbs mostly high frequencies. So while foam is cheaper per dollar in absorption you would spend more in long run getting your room sounding right with all foam vs good quality panels from places such as GIK, ATS, Real Traps, etc. It may cost more upfront, but you would save money in long run by doing it right. Not to mention you get free advice from GIK and others to help you decide what you need without over purchasing panels.


Thanks a bunch for that, I'll have a look into the GIK panels! The back wall is mostly 1.5" foam, should I replace this with something thicker ie a wall of 4" fiberglass? 

Sent from my SM-G920F using Tapatalk


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## ereed

monty6400 said:


> Thanks a bunch for that, I'll have a look into the GIK panels! The back wall is mostly 1.5" foam, should I replace this with something thicker ie a wall of 4" fiberglass?
> 
> Sent from my SM-G920F using Tapatalk


If you are close to the back wall (less than 8 feet) then you want full broadband panels that absorb low as well since bass buildup on the rear wall as well. Thicker the panel, the better!


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## monty6400

ereed said:


> If you are close to the back wall (less than 8 feet) then you want full broadband panels that absorb low as well since bass buildup on the rear wall as well. Thicker the panel, the better!


I think I will replace the foam with some panels, should I replace the foam on the front wall aswell? I'll post a picture to show what it's like.









Sent from my SM-G920F using Tapatalk


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## ereed

monty6400 said:


> I think I will replace the foam with some panels, should I replace the foam on the front wall aswell? I'll post a picture to show what it's like.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my SM-G920F using Tapatalk


You don't need to remove the foam on the front screen wall....you could add bass traps in the corners in addition to it. Just looking at your photo alone, looks like you will benefit from "first reflection point" panels to improve the sound. Not sure if you have any bass traps or any panels other than the foam but at least do first reflection points and add broadband bass traps in corners and rear wall if you can.


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## monty6400

ereed said:


> You don't need to remove the foam on the front screen wall....you could add bass traps in the corners in addition to it. Just looking at your photo alone, looks like you will benefit from "first reflection point" panels to improve the sound. Not sure if you have any bass traps or any panels other than the foam but at least do first reflection points and add broadband bass traps in corners and rear wall if you can.


If you can see in the picture the first reflection point for the l channel falls between the window and the wall, will a panel below the window still work? Also do I treat first reflection points on the ceiling also? 

Sent from my SM-G920F using Tapatalk


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## ereed

monty6400 said:


> If you can see in the picture the first reflection point for the l channel falls between the window and the wall, will a panel below the window still work? Also do I treat first reflection points on the ceiling also?
> 
> Sent from my SM-G920F using Tapatalk


Using the mirror trick, put the panels where the tweeter can be seen from your seating. Panels should be ear height. As far as the window is concerned they make panels that work on stands where you can stand them vertically upright without mounting it on walls. While window is in the way you would still get benefit putting a standing panel there as well as opposing wall and ceilings. GIk has free help where you can email them your questions and your room pics and they help you narrow what you need based on budget, etc.


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## monty6400

ereed said:


> Using the mirror trick, put the panels where the tweeter can be seen from your seating. Panels should be ear height. As far as the window is concerned they make panels that work on stands where you can stand them vertically upright without mounting it on walls. While window is in the way you would still get benefit putting a standing panel there as well as opposing wall and ceilings. GIk has free help where you can email them your questions and your room pics and they help you narrow what you need based on budget, etc.


Again thanks for that, I'll send them an email asap and see what they say!

Sent from my SM-G920F using Tapatalk


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## huse0054

OK go easy on me... I am getting my mixed use, basement, family room setup for video and sound. My question pertains to what I could do if anything to improve the acoustics of the room. Room is 12'x25' with a large brick fireplace on the left sidewall, TV on the 25' wall and the basement stairs coming down the right sidewall, I also have a large fish tank on part of the back wall dividing the other half of the basement (of about equal size) behind the "living room". I will have a remote operated shade that will drop down in front of the fish tank to provide light blocking and minimal sound blocking when TV is on. Any outside the box ideas to help minimize 1st reflections? I was thinking of some sort of acoustic panel treatment that could lay flat on the ceiling and be tilted down to help cover some of the brick fireplace. I am stuck between do something in hopes of helping, or do nothing and live with the way the room is.
Thoughts?


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## huse0054

Here is the right side of the room.


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## Ladeback

huse0054 said:


> OK go easy on me... I am getting my mixed use, basement, family room setup for video and sound. My question pertains to what I could do if anything to improve the acoustics of the room. Room is 12'x25' with a large brick fireplace on the left sidewall, TV on the 25' wall and the basement stairs coming down the right sidewall, I also have a large fish tank on part of the back wall dividing the other half of the basement (of about equal size) behind the "living room". I will have a remote operated shade that will drop down in front of the fish tank to provide light blocking and minimal sound blocking when TV is on. Any outside the box ideas to help minimize 1st reflections? I was thinking of some sort of acoustic panel treatment that could lay flat on the ceiling and be tilted down to help cover some of the brick fireplace. I am stuck between do something in hopes of helping, or do nothing and live with the way the room is.
> Thoughts?


So you are wanting to put the TV on the wall across from the fish tank? I put above the fireplace or mount a retractable Acoustic Screen that would come down from the ceiling and put your LCR in the openings in your fireplace. You could have a rowof three seats then aback bar behind it with bar stools. Is there wall space next to the fish tank to mount surrounds?


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## dnoonie

huse0054 said:


> Here is the right side of the room.


The first thing that came to mind was a wheeled movable "wall"/room divider with acoustic treatment on it. I'm not sure you have the space to store something like that when not in use but it could be used temporarily to convert the space into something more acoustically acceptable. Just an idea, not sure it will work for you.

I got rid of the "seat" in front of my fireplace and just put marble tile on the floor (shield, concrete board, then marble all to code), it creates more space without it. To brighten the room I covered the dark brick with marble as well.. My HT room doesn't have a fireplace, thank goodness, but I have hung treatment on the doors.

Cheers,


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## huse0054

dnoonie said:


> The first thing that came to mind was a wheeled movable "wall"/room divider with acoustic treatment on it. I'm not sure you have the space to store something like that when not in use but it could be used temporarily to convert the space into something more acoustically acceptable. Just an idea, not sure it will work for you.
> 
> I got rid of the "seat" in front of my fireplace and just put marble tile on the floor (shield, concrete board, then marble all to code), it creates more space without it. To brighten the room I covered the dark brick with marble as well.. My HT room doesn't have a fireplace, thank goodness, but I have hung treatment on the doors.
> 
> Cheers,


I was thinking about a movable "acoustic" wall to help with the brick as well, but I would not have the space to store when not in use, maybe something that drops down from the ceiling. I have not listened to sound in the room yet but am thinking ahead and assume the large brick wall will not lend itself to treatment. With the TV and sound on the long wall and the Fireplace to the left I am not sure how I am going to acoustically treat the first reflections or even if that would do much given how much brick there is. I wonder if 3 or 4 acoustic panels that would fold down when watching a movie would help at all. Unfortunately, or fortunately it is a mixed use space and my wife and I like the fireplace and plan on using it. I am white washing the brick to lighten the space. 



Ladeback said:


> So you are wanting to put the TV on the wall across from the fish tank? I put above the fireplace or mount a retractable Acoustic Screen that would come down from the ceiling and put your LCR in the openings in your fireplace. You could have a rowof three seats then aback bar behind it with bar stools. Is there wall space next to the fish tank to mount surrounds?


Interesting idea and I like the concept but my wife would not go for that


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## Ladeback

huse0054 said:


> I was thinking about a movable "acoustic" wall to help with the brick as well, but I would not have the space to store when not in use, maybe something that drops down from the ceiling. I have not listened to sound in the room yet but am thinking ahead and assume the large brick wall will not lend itself to treatment. With the TV and sound on the long wall and the Fireplace to the left I am not sure how I am going to acoustically treat the first reflections or even if that would do much given how much brick there is. I wonder if 3 or 4 acoustic panels that would fold down when watching a movie would help at all. Unfortunately, or fortunately it is a mixed use space and my wife and I like the fireplace and plan on using it. I am white washing the brick to lighten the space.
> 
> 
> 
> Interesting idea and I like the concept but my wife would not go for that


I totaly understand. I want to move my 120" screen and projector up to our living room so I can put in a bigger screen in my makeshift theater, but my wife won't go for it so I won't even ask. Our living room is wired for 5.2 surround and we have a 60' TV, but it is 10 years old and needs updated to 75" since the room is 18.5'x26'x12'.


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## dnoonie

huse0054 said:


> I was thinking about a movable "acoustic" wall to help with the brick as well, but I would not have the space to store when not in use, maybe something that drops down from the ceiling. I have not listened to sound in the room yet but am thinking ahead and assume the large brick wall will not lend itself to treatment. With the TV and sound on the long wall and the Fireplace to the left I am not sure how I am going to acoustically treat the first reflections or even if that would do much given how much brick there is. * I wonder if 3 or 4 acoustic panels that would fold down when watching a movie would help at all. *Unfortunately, or fortunately it is a mixed use space and my wife and I like the fireplace and plan on using it. I am white washing the brick to lighten the space.
> 
> 
> 
> Interesting idea and I like the concept but my wife would not go for that


Check these out,
http://www.gikacoustics.com/product-category/gobos-screen-panel-vocal-booth/
https://www.acoustimac.com/acoustic-panels/acoustic-booths-dividers. 

Cheers,


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## HarpNinja

I am about to embark on some DIY panels. I am prepared to put panels at first reflections on the side walls between the speakers and couch, behind my L and R channels, and will not be able to place them on my back wall.

My side surrounds are at 100 degrees and at ear height (5.1.4 set up). They are in walls, so I have the following options....

1. Panels between the side surround and couch
2. Panels behind the side surround and couch
3. Panels over the side surrounds with a space cut for the speaker
4. No panels for the side surrounds

If it helps in placement, my back Atmos speakers sit behind the side surrounds. Thoughts? Aesthetically, it might look best to have the in walls covered by panels. I would imagine doing that with cut outs for the speaker would be fairly straight forward.

THANKS!


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## IAH

Is it ok to use screening such as this: https://www.lowes.com/pd/Saint-Gobain-ADFORS-Fiberglass-Screen-Wire/3087645 to "contain" the insulation for a panel?

Much the way this guy made his panels:


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## Ladeback

IAH said:


> Is it ok to use screening such as this: https://www.lowes.com/pd/Saint-Gobain-ADFORS-Fiberglass-Screen-Wire/3087645 to "contain" the insulation for a panel?
> 
> Much the way this guy made his panels:
> https://youtu.be/GBHYiWIJhUA


I would think it would work to help keep the back in, but wonder if it is necessary for the front.


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## asarose247

@IAH

by my experience, the screening is ok for retention
but I prefer to go with something tighter weave and more AT and thinner for primary fiber control,

there are voile curtains on Amazon which are imo more AT, and by the ft^2, less expensive,
so I can spend more on 703
since you'll be attaching with staples, clamp an edge pull tight. clamp the opposite edge.
on a 3rd edge in the center, pull tight. then do it on the 4th edge. look it over. you'll get the hang of it

you do use a pneumatic stapler , right,. on my last project I emptied my 2nd box of 5,000 plus a few extra . .

unless decorative style dictates, I use similar fabric for a top cover and sometimes speaker grill cloth . .

the front cloud is 1 of 3 x 3'x4', 5" thick first reflection ceiling clouds, plus a smaller 1 for total 40 ft^2
.by using the drywall corners , I can secure a 2x4 2" 703 panel well enough to let the edges also be exposed for more surface area and when wrapping it, don't crush the corners for the tight right no sags or wrinkles "look".

HTH


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## IAH

^
Hey those are great tips asarose! Thanks.

I ended up using it and it seemed to work after I installed it re-ran REW, and looked at the ETC. The reflection from the rear wall was gone! Now to make another one for the side wall.

Thanks guys.


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## asarose247

@IAH

could you post a before and after REW capture of that?

I have a bare rear wall and 2 empty corners , (room is < 100 ft^2)

I don't know it for a fact,
BUT there must be _something_ to do back there,

I just know it's true . . 

and I have a full 6 pack of 2" 703 aging in its shipping carton . . 

Do you have any before/after bass trapping data

TIA


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## IAH

Yes I will post them tomorrow as they're on my other laptop.

It's my first acoustic panel. Prior to that, all I had done to treat my room was put 2'x2'x2' square stacks of denim insulation (which I had left over from a speaker build) in 2 corners of the room as sort of an experiment to see if I would notice a difference in bass response. And I did notice a difference! It may not be the best solution, but it sounds a hell of a lot "tighter" and "clearer". I can start to hear the different bass notes as apposed to the ol' "one note bass" curse. My waterfall graph improved quite a bit as well to confirm what I was hearing. Much less ringing. 

I have read several posts from the experts saying that if you sit close to your rear wall, or right up against it as I do, it's absolutely essential to treat it, and not necessarily with diffusion. So I tried the panel there. It's a 4'x4'x3" panel with safe and sound insulation, and I noticed an IMMEDIATE improvement in clarity and "warmth", in dialogue in particular. So today I built another one which is 4'x4'x*6"* which I think I'll put on the rear wall and put the other one on the side wall (the ceiling is, sadly, not an option at the moment).

But I have to say, my system sounds remarkably better since I've applied some basic treatment to it. Thanks to all who have contributed to this (yet another gold mine on avsforum) thread!


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## donktard

Does anyone have info how much does acoustic panel rock/mineral wool contaminate air in room when covered with fabric? I am not overly concerned given my previous experiences (I'd expect to see some fibers on fabric surface if it was coming out regularly) but I'm curious.
Also, did anyone here bother make panels with slotted/perforated panels in front instead of just typical fiber cover?


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## jln1980

*Leftover Duct Liner*

I have some leftover 1 inch duct liner could i take and cut it to fit in my acoustical panels? I would double up and use at least 2 inches, would even go more if recommended. ​


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## wingm8

I have an extra case of green glue (Qty: 12, 29 oz. tubes). You pay for shipping and they're yours. PM me.

Edit: Gone


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## IAH

*Fabric NOT acoustically transparent*

So, I built a 6" acoustic panel the other day and covered it in a fabric (upholstery) from Joann's which I thought was acoustically transparent (I could breath through it, though not with ease). After I hung it on the rear wall, I ran some sweeps to see if the reflection was still there, and it was! I couldn't believe it! So I flipped it around to the uncovered side and re-ran REW, and the reflection was gone!

Just sayin...

The first picture is with the panel covered. The second is uncovered. The red dot is where the reflection point was at ~1.9' (which is the rear wall. The spike just to the left of it is at 1.53'(that one must be SBIR or something). But notice how the spike is greatly reduced after the panel is flipped!


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## HopefulFred

That's interesting. Do you have nay techniques to tell you what the spectrum of that reflection is?


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## IAH

I do not, though I'm not very experienced with taking and analyzing measurements. One of the experts may know of a way.


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## killswitch1968

Looking for some advice on fabric walls.

Are the fabric walls I see in many of the pictures stuffed with anything? If so, and if it's uniform around the room, won't that deaden to many mids and highs? And if they are hollow inside, wouldn't it feel like a trampoline if you lean against a wall with no padding? Not sure how I can get that fabric look without mechanical or acoustical issues.


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## malba2366

*705 vs Linacoustic*

It seems that most people on here building fabric walls use 705 panels as the backer. I reviewed the data sheets on 705 and linacoustic and it seems like the performance is almost identical. Linacoustic is also about a third of the price as 705 and is readily available at HVAC suppliers. Is there any benefit to using the 705 panels? I am planing a 1 inch thick fabricmate wall on the side and backs of the theater (back of screen wall will be treated with linacoustic as well).


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## killswitch1968

malba2366 said:


> It seems that most people on here building fabric walls use 705 panels as the backer. I reviewed the data sheets on 705 and linacoustic and it seems like the performance is almost identical. Linacoustic is also about a third of the price as 705 and is readily available at HVAC suppliers. Is there any benefit to using the 705 panels? I am planing a 1 inch thick fabricmate wall on the side and backs of the theater (back of screen wall will be treated with linacoustic as well).


I thought most people used Linacoustic actually; The Home Theater Books is full of theaters that were using that.


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## malba2366

killswitch1968 said:


> I thought most people used Linacoustic actually; The Home Theater Books is full of theaters that were using that.


Cool...Linacoustic it is then. Its readily available locally and is a lot cheaper. Thanks!


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## Rengozu

Hello, my room size is about 14ft wide and 24 feet deep with 8ft ceilings.
For acoustic panels I currently have these from Acoustimac: 

On the back wall:
2 Corner bass traps (36"x24"x4")
2 Soundlock acoustic panels (56"x30"x1")

On the ceiling:
1 Super Size panel up front (8'x4'x2")
1 Extra Large panel in the back (6'x4'x2")

On the sides:
16 Sound Absorbing panels towards the sitting area (1'x1'x2")
4 Soundlock acoustic panels towards the front (56"x34"x2")

Kinda went into a lot of this build blind with a little trial and error along the way. Main thing is I just planned on putting the framed wall panels where they are because the frame is holding the piece that's covering the former window space. 
With the panels I have up now it sounds so much better than it did originally without them, and I actually think it sounds great, but still wanted to post here to see if anyone had any further advice for me to try. Diffusers for example. I currently don't have any of those and don't know if or where they're needed or how to tell. 

Know some will probably rip into me for not having anything on my main screen wall. Any advice or critique welcome. 

(room pictures for reference)


Spoiler


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## tjcinnamon

*Absorption Coeffient of Wall Rug*

So I am treating my back wall with sound absorption (to clean up reverb). Would a heavy wall rug have the same or similar impact as home made absorption panels (using 703 or denim)? I may be able to convince my wife to get more of the back-wall treated and then can use my "absorption capital" on some corner paneling for my 2nd order reflection points/corners. The space I am trying to fill is 6' x 3' and a printed picture may be too much for DIY (otherwise, I could do 3 3x2 panels). 

My seating is close to the back wall so that's why I'm focusing on that wall. 

Here's 2" 703 from Bob Golds
0.17 0.86 1.14 1.07 1.02 0.98

This has the absorption coefficient of Drapery (18 oz/yd2, 612 g/m2, flat against wall). I think the rug may be heavier: https://www.acoustic-supplies.com/absorption-coefficient-chart/ There's also the chance that this may be incorrect. There is a massive disparity between 703 and the rug and given that mass really effects bass, I'm surprised the mid-bass and bass regions are so not impacted. 

0.05 0.12 0.35 0.48 0.38 0.36


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## abinav555

Would a 100% absorption rooms make sense for a home theatre. i have a guy who builds music studios all over my city and is strongly against putting up diffusers and bass traps.
He is basically going for a full flat response just like he is doing with his studios. He however says diffusers can always be put up at a later stage if i want a more lively sound. Looking for some suggestions. Some people who I have discussed with have told me that such a room has too much dampening and is not recommended for a home theater as it not meant for critical listening.


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## sdurani

abinav555 said:


> Would a 100% absorption rooms make sense for a home theatre.


ONLY if you like the resulting sound (most people don't).


> i have a guy who builds music studios all over my city and is strongly against putting up diffusers and bass traps.


There is a difference between a work/production environment (where the mix is constantly under a magnifying glass) versus a recreational listening space (where you're listening for pleasure).


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## abinav555

sdurani said:


> ONLY if you like the resulting sound (most people don't). There is a difference between a work/production environment (where the mix is constantly under a magnifying glass) versus a recreational listening space (where you're listening for pleasure).


I have a strong feeling I might not like it. My question is, can I put diffuser/bass traps later to make it more lively ?


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## sdurani

abinav555 said:


> I have a strong feeling I might not like it. My question is, can I put diffuser/bass traps later to make it more lively ?


Sure you can add diffusers later. But why start off with acoustics that you have a strong feeling you might not like? If you're going to hire someone to do your room, shouldn't the acoustics be based on what you like rather than his preference? It's not like he's the one having to live with the room afterwards. Personally, I'd be wary of the my-way-or-highway types.


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## abinav555

sdurani said:


> Sure you can add diffusers later. But why start off with acoustics that you have a strong feeling you might not like? If you're going to hire someone to do your room, shouldn't the acoustics be based on what you like rather than his preference? It's not like he's the one having to live with the room afterwards. Personally, I'd be wary of the my-way-or-highway types.


True. I've had a discussion about this with him and he has agreed to induce reflections into the room.


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## erwinfrombelgium

The thing with diffusers is they need some distance to do their magic. Absorption doesn't. I have a wide room and used nothing but diffusion on the side walls. But I used plenty of thick absorption on the ceiling which is of standard 8 1/2ft height. I haven't measured yet, but I love the sound already using very old abused speakers.


----------



## artsci2

tjcinnamon said:


> ..... Would a heavy wall rug have the same or similar impact as home made absorption panels ....
> ....My seating is close to the back wall so that's why I'm focusing on that wall.


The rug or any other


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## mcallister

Any thoughts if this would be good to use to cut into triangles for floor to ceiling corner traps?

https://indianapolis.craigslist.org/mat/d/mineral-wool-insulation-board/6463902204.html


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## VideoGrabber

mcallister said:


> Any thoughts if this would be good to use to cut into triangles for floor to ceiling corner traps?
> 
> https://indianapolis.craigslist.org/mat/d/mineral-wool-insulation-board/6463902204.html


Yes. And $80/corner is also economical.


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## HoffBerry

*Acoustical Treatment for 17x21x9 room?*

Team, I am building out a dedicated media room and I know nothing about acoustical treatments, bass traps, etc. What I can tell you is that the room is 17' wide by 21' deep and 9' ceiling. 2 rows of 4 seats. The floor will be carpeted with a riser for the second row. Equipment is 2 Def Tech BP9060 towers, 1 CS9060 Center, 2 DI 6.5 LCR's, 4 DI 5.5BPS Surrounds, 4 Sonance Atmos speakers and 2 SVS SB16 Ultra Subs. Running on Yamaha 3070 receiver. Don't want to spend a ton hear but don't want to be cheap either. Any advise on what to use/install would be greatly appreciated. Thanks!


----------



## imureh

HoffBerry said:


> Team, I am building out a dedicated media room and I know nothing about acoustical treatments, bass traps, etc. What I can tell you is that the room is 17' wide by 21' deep and 9' ceiling. 2 rows of 4 seats. The floor will be carpeted with a riser for the second row. Equipment is 2 Def Tech BP9060 towers, 1 CS9060 Center, 2 DI 6.5 LCR's, 4 DI 5.5BPS Surrounds, 4 Sonance Atmos speakers and 2 SVS SB16 Ultra Subs. Running on Yamaha 3070 receiver. Don't want to spend a ton hear but don't want to be cheap either. Any advise on what to use/install would be greatly appreciated. Thanks!




One suggestion would be to reach out to GIK acoustics and they help with recommendations based on your room. Not the cheapest but are good quality and you don’t need to get everything at the same time either. 


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## ncabw

I’m looking at adding some DIY sound panels and have some questions. Basically this was suppose to be a sports room which has turned more into a home theater setup. Since this originally was a sports themed room I have lots of jersey I will need to hang on the walls along with the sound panels. 

I have a 7.1.4 setup. 

1)Can I do the mirror trick with just the front speakers
2)because I have speakers 4,5,6,7 on the side walls directly across each other would that mean I wouldn’t have to treat them?
3) back wall can I just do 3 panels directly across the 3 front speakers?
4)ceiling I don’t mind adding lots of panels between my lights if that helps. 
5) A’s you can see in pic. I made one panel using roxul safe and sound. Doubled the insulation so it’s 6”. I would rather do 3”. Can I.
6) if roxul has a better product. Let me know I can order anything in from a local supplier. 
7) bass traps in all 4 corners?




















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## Blue

I'm struggling to find Linacoustic in the Atlanta area. A supplier has Knauf Atmosphere Duct Liner in rolls. Will it work as well? It's listed as having a density of 1.5 PCF, 1" thick, with an R Value of 4.2. Here is the product: http://www.knaufinsulation.us/en/content/atmosphere-duct-liner-0 

What's the current best recommendation for treating the front wall? I've read (a) 1 inch duct liner on the entire front wall, (b) 1 inch duct liner, then a 3 mil plastic sheet, then another layer of 1" duct liner on the entire wall, (c) 1 inch duct liner only behind the screen, i.e., not the entire wall, or finally (d) 1" duct liner / 3 mil plastic / 1" duct liner, but only behind the screen, i.e., not the entire wall.

Thanks in advance for your help.


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## LydMekk

One layer of LA, thin layer of plastic, then another layer of LA.
That's the way to do it.
Or as I did, I got LA with one side covered by thin metal, placed the two metal layers towards one another in the center and skipped the plastic.


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## Blue

LydMekk said:


> One layer of LA, thin layer of plastic, then another layer of LA.
> That's the way to do it.
> Or as I did, I got LA with one side covered by thin metal, placed the two metal layers towards one another in the center and skipped the plastic.


Thanks. Would you treat the entire front wall or only the area behind the screen? 

Any thoughts on the Knauf duct liner I linked above? I can't find linacoustic so far in Atlanta.

Anyone now where I can buy linacoustic in Atlanta?


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## LydMekk

Whole front wall, corner to corner. I even treated the first 80cm out from the front corners on the side walls.
See my thread in my signature, pictures of the process.


----------



## ncabw

ncabw said:


> I’m looking at adding some DIY sound panels and have some questions. Basically this was suppose to be a sports room which has turned more into a home theater setup. Since this originally was a sports themed room I have lots of jersey I will need to hang on the walls along with the sound panels.
> 
> I have a 7.1.4 setup.
> 
> 1)Can I do the mirror trick with just the front speakers
> 2)because I have speakers 4,5,6,7 on the side walls directly across each other would that mean I wouldn’t have to treat them?
> 3) back wall can I just do 3 panels directly across the 3 front speakers?
> 4)ceiling I don’t mind adding lots of panels between my lights if that helps.
> 5) A’s you can see in pic. I made one panel using roxul safe and sound. Doubled the insulation so it’s 6”. I would rather do 3”. Can I.
> 6) if roxul has a better product. Let me know I can order anything in from a local supplier.
> 7) bass traps in all 4 corners?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPad using Tapatalk




Bump 


Sent from my iPhone using Tapatalk


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## erwinfrombelgium

_1)Can I do the mirror trick with just the front speakers_
That would be the most bang for buck, yes.

_2)because I have speakers 4,5,6,7 on the side walls directly across each other would that mean I wouldn’t have to treat them?_
No, the opposite wall will reflect in a different spot. I would line all ear level speakers at the same height and add absorption in between all of them so you have an array of absorption interrupted with speakers. It only needs to be 2' high. Diffusion can be added above if you want the very best.

_3) back wall can I just do 3 panels directly across the 3 front speakers?_
No, mirror trick applies here also. Back wall is a good wall for full absorption. 

_4)ceiling I don’t mind adding lots of panels between my lights if that helps._ 
Good! An island of absorption centered above listening area

_5) A’s you can see in pic. I made one panel using roxul safe and sound. Doubled the insulation so it’s 6”. I would rather do 3”. Can I._
3" is ok for the sidewalls but having a gap of no more than 3" between it and the wall will be almost as good as 6" against the surface without any gap. Gap should never be bigger than panel otherwise there will be some frequencies "escaping" treatment.

_7) bass traps in all 4 corners?_
Certainly if it's a brick or concrete construction behind it. IMO, wood framing lets pass through a lot of the lowest stuff. And you can tame bass with Dirac DRC.


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## ncabw

erwinfrombelgium said:


> _1)Can I do the mirror trick with just the front speakers_
> 
> That would be the most bang for buck, yes.
> 
> 
> 
> _2)because I have speakers 4,5,6,7 on the side walls directly across each other would that mean I wouldn’t have to treat them?_
> 
> No, the opposite wall will reflect in a different spot. I would line all ear level speakers at the same height and add absorption in between all of them so you have an array of absorption interrupted with speakers. It only needs to be 2' high. Diffusion can be added above if you want the very best.
> 
> 
> 
> _3) back wall can I just do 3 panels directly across the 3 front speakers?_
> 
> No, mirror trick applies here also. Back wall is a good wall for full absorption.
> 
> 
> 
> _4)ceiling I don’t mind adding lots of panels between my lights if that helps._
> 
> Good! An island of absorption centered above listening area
> 
> 
> 
> _5) A’s you can see in pic. I made one panel using roxul safe and sound. Doubled the insulation so it’s 6”. I would rather do 3”. Can I._
> 
> 3" is ok for the sidewalls but having a gap of no more than 3" between it and the wall will be almost as good as 6" against the surface without any gap. Gap should never be bigger than panel otherwise there will be some frequencies "escaping" treatment.
> 
> 
> 
> _7) bass traps in all 4 corners?_
> 
> Certainly if it's a brick or concrete construction behind it. IMO, wood framing lets pass through a lot of the lowest stuff. And you can tame bass with Dirac DRC.




For #5 can 1 do 1” or less with the 3” insulation?

And for number 3 mirror trick do I just turn around in my chair to see where the speakers will be located? I can’t find any videos of people doing a back wall. 

Thanks 


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## tcramer

I'm looking to finalize my wall fabric selection and am wondering if anyone has insight between a few GOM fabrics and the acoustical properties.

The designer typically uses GOM Anchorage. However, we like color options from Highbeams, Intuition or Galaxy better. From an acoustical perspective knowing these will be covering the treatments and ceiling/surround speakers, are they are fairly comparable or is one superior? I cannot really tell from the limited GOM site info and haven't been able to find info elsewhere.

We like these colors/patterns better, but certainly don't want to compromise performance.

Thanks!


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## erwinfrombelgium

ncabw said:


> For #5 can 1 do 1” or less with the 3” insulation?
> 
> And for number 3 mirror trick do I just turn around in my chair to see where the speakers will be located? I can’t find any videos of people doing a back wall.
> 
> Thanks
> 
> 
> Sent from my iPhone using Tapatalk


You certainly can use 3" material with 1" gap at the cost of a slightly higher treated frequency range. But still decent.

All surfaces are important. For the rear wall, you should at least try to treat 2/3 of the width of the LCR speakers, about 2' high. While some reflections on the sidewalls help retain the sound energy, you don't want that energy to reflect behind you and potentially cancel sound from the front.


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## Blue

I angled my side speakers and wound up with 30" by 7" spaces on each side of the room on the front wall to the sides of where the screen will go. I was thinking about stacking 30" wide by some depth (12" would look nice, but theoretically, I could make them deeper) insulation in those front corners and covering them with fabric to make floor to ceiling base traps. Is this worthwhile? I've read extensively, but I swear I see different answers every time I search and read threads. 

Here's a picture from my build thread of the space next to the angled speaker niche: http://www.avsforum.com/forum/attachment.php?attachmentid=2357604&d=1518046027


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## swestswest

I am in the process of finally finishing my build. I put up sound proof panels (DIY) made of Rockwool 60 at 1.5 inch thick. I put them on my reflection points using a mirror and it has killed the spaciousness of movies etc. I read a few items where you need this and some that say side wall reflections are your friend when it comes to movies. Have you seen this in your practices? I took them down and the fullness of the front stage came back. Maybe good for the back wall?


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## sdurani

swestswest said:


> I read a few items where you need this and some that say side wall reflections are your friend when it comes to movies. Have you seen this in your practices?


Sure. I tried absorbers & diffusers at sidewall first reflection points and kept coming back to bare walls. Personal preference.


> I took them down and the fullness of the front stage came back. Maybe good for the back wall?


I would still leave up the absorbers that are at the contralateral reflection points (left speaker's reflection off the right wall, and vice versa). This way, sounds intended for one end of the soundstage are not coming at you (however subtly) from the opposite side of the room. Would move absorbers from the ipsilateral reflection points to the middle of the back wall (directly opposite the centre speaker).


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## swestswest

sdurani said:


> Sure. I tried absorbers & diffusers at sidewall first reflection points and kept coming back to bare walls. Personal preference. I would still leave up the absorbers that are at the contralateral reflection points (left speaker's reflection off the right wall, and vice versa). This way, sounds intended for one end of the soundstage are not coming at you (however subtly) from the opposite side of the room. Would move absorbers from the ipsilateral reflection points to the middle of the back wall (directly opposite the centre speaker).


So treat my left and right speakers second reflection points with absorbers and the back wall reflection. Ill give it a try.
What a difference it made not absorbing the first reflection point. My guess is every room is different.


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## sdurani

swestswest said:


> So treat my left and right speakers second reflection points with absorbers and the back wall reflection.


Those aren't second reflection points, they're the first reflection points of the speakers on the opposite side of the room.


> What a difference it made not absorbing the first reflection point.


Gave my set-up a wider soundstage and greater spaciousness.


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## swestswest

sdurani said:


> Those aren't second reflection points, they're the first reflection points of the speakers on the opposite side of the room. Gave my set-up a wider soundstage and greater spaciousness.


Sorry for going back and forth, so treat the first reflection point of the opposite speaker? just didn't understand the contralateral and ipsi.... point. Im new to all this, new hobby or mid life crisis lol


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## sdurani

swestswest said:


> Sorry for going back and forth, so treat the first reflection point of the opposite speaker?


Yes, instead of getting rid of all your absorption panels on the side walls, try leaving the ones that absorb the opposite speakers' first reflections.


> just didn't understand the contralateral and ipsi.... point.


You could have just typed those words into Google.


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## Mahuzz13

I have a question regarding ceiling treatments. My room is 17 x 21 x 7’6”, I have a support beam running at the half way point of my theatre. So the front seating are in the first have and second row and sit up bar are in the other side of the beam. Not sure if you need the speakers I will be using for my set up just let me know if you do. I will be having hardwood through with an option of maybe a rollout area carpet. From screen to beam is about 9’, I have 4 pot lights going in and 2 atmos speakers as well, my ultimate goal would be able to hide all of that within the treatment. Would I need just absorption or both absorption/diffusion, how thick of absorption should I have. Thanks for your help.








I was thinking of having the treatments within the yellow tape area. 
Forgot to mention I will be having wall treatments behind fabric 

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## erwinfrombelgium

Diffusion needs distance to work hence on a lowish ceiling, IMO absorption is preferred. 

Do it as thick as possible, but 3" will work. Mo' is bettah.


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## corradizo

Hi Guys,

This is what is behind my screen. 










This is how I've treated it with r19 OC Batts.










Is this an acceptable approach? My screen is AT and their will be panels made of syfabrics triple black Velvet around it.




























Thanks,

Pete


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## Helheim

Since we don't have Tractor Supply stores around here does this stuff look similar to what people use on floors? What would be the best floor option on concrete that takes up the least amount of inches?

https://perfectsurfaces.ca/product/gator-rolled-pro-series/

Thanks


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## Garman

New house with unfinished basement, just curious on some suggestions.. Wife wants more of an open concept, and I need an office. We have a walk out basement, thinking of doing bar area their. Is there a way to make the room sound decent with more of an open concept? This is a walk out basement and I don't want the Theater to be the traffic and or pass through area. Need Space for storage and an office as well, hence the open concept seems more feasible. Also the best insulator for sound, I heard Denim material, but read it's horrible if it gets wet.


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## Craig Gordon

I would just like to add a quick idea I used for ceiling treatment. And yes, sometimes you want and should have some ceiling treatment. Anyway in a covered fabric situation to hold whatever insulation you decide on up to the ceiling without the insulation breaking apart, I used very inexpensive 1/32 of an inch thick, 2 inch diameter "washers" made of acrylic. Sold as "Plastic Disks" on the internet.


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## ack_bk

Honestly, this is all very confusing as there is so much conflicting information out there. I have already treated my front wall with Knauf 2" insulation board. Carpet is down with 10lb pad (so floor is treated). We have two rows of fabric theater chairs (I would think that is a form of absorption). I have four columns and lots of trim (wainscoating, picture frame moulding, baseboards, crown moulding) and I would think that would act as some diffusion?

After watching several videos from MSR Acoustics, my initial thought it to go with some combination absorption/diffusion panels (GIK has some nice looking ones that look like art) for the side walls. A few regualr absorption panels for the rear wall, and perhaps a few more absorption panels for the ceiling.

Per MSR you don't want to treat more than 20% of the room surface. My thought was to start with a handful and then listen and measure. Thoughts?


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## LydMekk

No. Per MSR you want 20-25% absorption, 20-25% diffusion calculated of all the rooms surfaces. So, in total cover 40-50% of the surfaces in total. That includes ceiling and floor.


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## ack_bk

LydMekk said:


> No. Per MSR you want 20-25% absorption, 20-25% diffusion calculated of all the rooms surfaces. So, in total cover 40-50% of the surfaces in total. That includes ceiling and floor.


Thanks tat makes sense. Any thoughts on the combo absorption/diffusion panels. I like the idea of using those for main reflection points and absorption on ceiling.


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## Craig Gordon

ack_bk said:


> Per MSR you don't want to treat more than 20% of the room surface. My thought was to start with a handful and then listen and measure. Thoughts?


All I know is that I have a marble fireplace, and a marble coffee table in the room. Also a porcelain tile floor, but with a nice thick carpeted inset for about 60% of the floor space. For me, the room sounded much better with about 45% total absorption on all surfaces, with good absorption at the first reflection points from all speakers. After that it started to sound a bit muffled, but less then 45% sounded noticeably incoherent. Who knows, I just have it the way I like it.


----------



## ereed

ack_bk said:


> Thanks tat makes sense. Any thoughts on the combo absorption/diffusion panels. I like the idea of using those for main reflection points and absorption on ceiling.


GIK acoustics make Alpha panels which are mix of absorption and diffusion all in one panel. I'm using those and I love them!


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## kgveteran

I treated FRP with 4” OC703, i treated parallel walls with stepped diffusers (flutter echo). I made super chunk corner traps (2’x2’x8’) fluffy pink OC to dampen the low end, not the sub low end. 
The room sounds dead as dead.....until the movie starts, RFZ at the LP is nothing less than amazing.
An untreated room is like adding random EQ curves to ur system, remove the room with appropriate absorption, diffusers, dampening and you will hear all the intended soundtrack. Remove the room, the 11 (!!!!!) speakers will be heard. They will create all the space, reverb ect.


I did a lot of reading over on the Gearslutz forum, recording studio build, and acoustic treatments. I did minimal absorbtion on the FRP, which led to a stepped diffuser for the DIY Audio site http://www.diyaudio.com/forums/cons...iy-depot-sound-diffuser-panels-step-step.html . I used them on opposing walls, they cover 400hz-8khz, flutter echo is non issue now. Theres a lot of info out there. My side absorbers are fluffy pink OC 10" thick 4'x2' . what ever spills over slightly is caught by the diffusers...... This has been a great project !!


----------



## ack_bk

ereed said:


> GIK acoustics make Alpha panels which are mix of absorption and diffusion all in one panel. I'm using those and I love them!


That's exactly what I am looking at. They look good too


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## ack_bk

kgveteran said:


> I treated FRP with 4” OC703, i treated parallel walls with stepped diffusers (flutter echo). I made super chunk corner traps (2’x2’x8’) fluffy pink OC to dampen the low end, not the sub low end.
> The room sounds dead as dead.....until the movie starts, RFZ at the LP is nothing less than amazing.
> An untreated room is like adding random EQ curves to ur system, remove the room with appropriate absorption, diffusers, dampening and you will hear all the intended soundtrack. Remove the room, the 11 (!!!!!) speakers will be heard. They will create all the space, reverb ect.
> 
> 
> I did a lot of reading over on the Gearslutz forum, recording studio build, and acoustic treatments. I did minimal absorbtion on the FRP, which led to a stepped diffuser for the DIY Audio site http://www.diyaudio.com/forums/cons...iy-depot-sound-diffuser-panels-step-step.html . I used them on opposing walls, they cover 400hz-8khz, flutter echo is non issue now. Theres a lot of info out there. My side absorbers are fluffy pink OC 10" thick 4'x2' . what ever spills over slightly is caught by the diffusers...... This has been a great project !!


That's is great info, thanks.


----------



## kgveteran

One side effect of reduced reflection was, i was able to turn the volume up without the shrill of multiple center, left and right sounds. I do listen a little louder now. I would usually listen at -15db MV, now my norm is around -10db MV.

Its not always the reflections of mains or surrounds, its the flutter echo of sounds “trapped” between parallel walls on either side of the screen area.

Pefect example are my side surrounds that face each other, diffusion maintained the energy without reflecting.

Another effect of the super chunk corner traps is the dampening of the low end, sound effects stop when they are suppose to, the lowend reverb would allow low freq effects to remain in the room and muddy the next effect.

RFZ are not normal environments we are in day to day, they take time to realize. Its like hearing quality sub bass for the first time, when you remove the aweful midbass hump of distorted bass, You’re like.... where is the bass ????
It takes awhile to appreciate it....

An un treated room adds alot of unwanted effects, rooms do two thing real well, they store energy and reflect sound, thus ADDING sounds and effects to an already effect loaded soundtrack.

Not everyone can acoustically treat their rooms for many reasons, but untreated room DO NOT add space, they simple Congest the space you have, if you choose to call it space thats fine, but please dont go on a campaign to convince people that this is right, it simply is wrong. If you cant treat the room as you wish, thats fine, but its far from correct, its simply a choice you have made.

One last thought, nowhere in ANY books on acoustics do the professionals recommend an un treated listening environment,


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## cloudbuster

Well I finally decided to start my HT room.
The media center TV is on the wall with the windows.


what would you guys think I should get.
My final setup would be 5.2.2 but no ceiling speaker just add ons on top of the front speaker aiming up to bounce from the ceiling. 














thanks.


----------



## kgveteran

My first thought is how to treat reflections when ur going to be using reflections for ur Atmos channels.
Are u looking for a RFZ @ LP ?


----------



## cloudbuster

kgveteran said:


> My first thought is how to treat reflections when ur going to be using reflections for ur Atmos channels.
> Are u looking for a RFZ @ LP ?


the ATMOS add on wont be something I do soon, maybe in a few months after I have the 5.1 or 5.2 setup dialed in.

im new to this stuff so not sure what RFZ LP means.

I just been reading that you have to add some type of room acoustic panel and there are way to many to choose from so not sure what I need and something that wont look to out of place.


----------



## ereed

cloudbuster said:


> the ATMOS add on wont be something I do soon, maybe in a few months after I have the 5.1 or 5.2 setup dialed in.
> 
> im new to this stuff so not sure what RFZ LP means.
> 
> I just been reading that you have to add some type of room acoustic panel and there are way to many to choose from so not sure what I need and something that wont look to out of place.


You need to get your speakers setup prior to using room treatments since you need the speakers to do the "mirror trick" to find first reflection points.  Just get the system setup and working and enjoy and see if you like the sound....if you find it bright/dull, etc then that's when you will know what kind of treatments you need such as absorption/diffusion. But you can always start with corner bass traps though since bass is usually the problem.


----------



## cloudbuster

ereed said:


> You need to get your speakers setup prior to using room treatments since you need the speakers to do the "mirror trick" to find first reflection points. Just get the system setup and working and enjoy and see if you like the sound....if you find it bright/dull, etc then that's when you will know what kind of treatments you need such as absorption/diffusion. But you can always start with corner bass traps though since bass is usually the problem.


Thanks, would you happen to have a link to one


----------



## ereed

cloudbuster said:


> Thanks, would you happen to have a link to one


Google is your friend....just type corner bass traps in google and it will show you many brands to choose from. GIK is a good brand and I use them. There are also others. But you need to get your system rolling first before you buy room treatments otherwise you will have no idea which room treatments you need to see how your system sounds.


----------



## cloudbuster

ereed said:


> Google is your friend....just type corner bass traps in google and it will show you many brands to choose from. GIK is a good brand and I use them. There are also others. But you need to get your system rolling first before you buy room treatments otherwise you will have no idea which room treatments you need to see how your system sounds.


thanks, I was not aware it was better to do that later.

would get the system in and then see, but completely clueless as to what I would need as far as diffusion or absorb material.


----------



## kgveteran

cloudbuster said:


> but completely clueless as to what I would need as far as diffusion or absorb material.


Because you dont have any issues, once you do a little reading, u will be fine.

Research first reflection points, super chunk corner traps, absorbers, diffusion..... It will get repetitive and soon you will be reading redunt info, you'll be fine.

I like the studio build thread at gear slutz, lot to be learned from controlroom design and acoustic treatments from those boy over there. https://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/

Wts lets hear about the room, the root of all problems Lol. What are ur plans, dimensions ect


----------



## cloudbuster

Thanks, 

I would start reading some more.


----------



## kgveteran

cloudbuster said:


> Thanks,
> 
> I would start reading some more.


Yes ! Keep reading !


----------



## 900HP

I started the acoustic absorber panel construction for both my room and a buddy's. My room will have all black absorbers with the exception of the side walls which are the red. His side walls are the tan. We have more to do of course and bass traps to build. Just thought I'd share.


----------



## killswitch1968

900HP said:


> I started the acoustic absorber panel construction for both my room and a buddy's. My room will have all black absorbers with the exception of the side walls which are the red. His side walls are the tan. We have more to do of course and bass traps to build. Just thought I'd share.


Is the fabric just stapled to the back of the frames? Are those MDF frames?

Sent from my Nexus 6P using Tapatalk


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## 900HP

killswitch1968 said:


> Is the fabric just stapled to the back of the frames? Are those MDF frames?
> 
> Sent from my Nexus 6P using Tapatalk


Yeah. I had a lightweight white linen type fabric that was stapled to the back and then once they were loaded with the Rockwool I wrapped them with Guilford 701 fabric from ATS acoustics. 

The frames are a combination of 1x4's and 1x2's and are screwed together. That gives 1.5" of airspace behind 2" of Roxul AFB. These are for side walls and ceiling. The bass traps will be 1x6's with 4" of Roxul 80 and a 1.5" air gap. 

The above seemed an easy solution with minimal cutting.


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## HopefulFred

Broadband waterfall plots of my home theater show ringing and a rise in response from about 500Hz to about 700Hz. While listening to normal content I don't notice a problem that I can specifically tie to that frequency response/ringing problem, but dialog isn't quite as clear as I would like.

Listening to test tones, I have determined that there seems to be a strong spatial component to the response in that frequency range; when moving my head left-right through the listening position, I hear fairly dramatic changes in intensity.

My room already has a tuned bass absorber 4' tall by 8' wide occupying much of the space behind my acoustically transparent screen. This trap also serves as a speaker stand for LCR. The remainder of the screen wall is covered by two layers of 1" duct liner separated by 6 mil plastic. The room is almost exactly 12' wide by approximately 22' long. My LCR are DIYSG SEOS designs called "Cheap Thrills" - 15" midwoofer and 12" SEOS waveguide and tweeter. L and R and toed in pretty heavily.

My initial hunch is that diffusion or combination absorption/diffusion either to the side of the listening position or at the first lateral reflection point(s) would probably clear it up, but I'm not confident in that conjecture.

Does anyone have any input? Recommendations for further diagnostic tests? I don't want to build and install something that doesn't work (obviously).


----------



## MackGuyver

I just wanted to put in a plug for acoustic treatments - I wish I had installed them many, many years ago. The bang for the buck is insane compared to pretty much every other HT component.

I bought 4 of GIK Acoustics tri-trap corner bass traps about 18 months ago and added more bass traps and acoustic panels from there. I picked up the UMIK-1 last week and after figuring out REW, it turns out my room is +/-5dB from 8-20,000Hz, with a near-perfect house curve. I knew it sounded great, but I wasn't expecting such a an excellent measurement! All for somewhere around $1,000!


----------



## Mahuzz13

I am finishing my back wall in my HT and I was hoping sound could help me out on this. 

In between my rear surrounds I have about 5’w x 6’6”h and I was going to use that space for a bass absorption. I can go as deep as 8” but I was unsure if that would be to much and should I use roxul safe and sound or just batt insulation. Should I go the whole width and height? 

I will have 8 x um18s 10cu each, 4 up front, 2 nearfield and 1 on each side of the rear surrounds built into the wall. 

Thanks in advance for your help. 


Sent from my iPhone using Tapatalk


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## HopefulFred

For bass absorption, there is no such thing as too much. At the depth you are willing to do, lower density batt insulation turns out more effective.


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## ncabw

I have made 4 panels so far with roxul safe and sound. I made them out of 1x6 and only used one layer at the front so I have an air gap in the back of about 3”. My question is I was at my dads shop and found this stuff is it better to use then safe and sound? It has like a aluminum liner on the front and back faces. 

Should I stick with the Air gap or add 2nd layer of insulation? I think from what I’ve read the Air gap is better. 

Thanks in advance 













Sent from my iPhone using Tapatalk


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## HarpNinja

I have a 5.1.4 set up in my basement family room. Using the picture attached as a reference, the 120" projector screen is on the right side of the picture (off set toward the top of the pic), which I will refer to as the front wall. The left side (top wall in pic) is a straightforward wall where I can put panels.

The right side (bottom of pic) is where I am unsure. There is the open stairwell, and I am not sure if I need panels along that wall. Any thoughts?

I have ceiling speakers for Atmos and in walls for surrounds. I know I could put a panel with cut outs over the side surrounds, but it isn't a priority. I also can't put panels on the back (left of pic) wall. I can put them behind the front L and R speakers.


----------



## HopefulFred

HarpNinja said:


> The right side (bottom of pic) is where I am unsure. There is the open stairwell, and I am not sure if I need panels along that wall. Any thoughts?


Normally I don't (personally) encourage the use of treatments at first lateral reflection points, but this is probably a case where they are important. The nearby wall on the left of the listening position is going to produce the perception of a sound source to the left of where it should be. Dialog will (likely) sound like it's coming from the left side of the screen. The left channel will probably experience a little extra mid-range/bass boost (SBIR). The right channel will probably appear to sound from the center, or there-abouts. Treating the left wall with broadband absorption, both near the L speaker (SBIR - to correct the frequency response problem the placement near the wall is probably causing), as well as at the reflection point for the center and right channels, to help correct the imaging. 

I would personally hold off on installing treatment on the right wall until the left wall is treated. Depending on the effectiveness of your left wall treatment, you may need to match left and right - if the left wall treatment is only partially effective, it might balance out nicely, or the effect may get reversed (shifting everything to the right).


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## bfb1963

*Door at First Reflection Point*

I have a door that has a jamb 9" wide. I was going to do a double door, but with the way it would open to the inside, I could never get any wall treatments where the door would swing against, nor could I place door mounted treatment. I am going to ditch the double door, and just use a massive outside door with acoustic sweeps. My First Reflection Point plan is to treat the ceiling and use acoustic absorbing carpet ( Acoustic Carpet ). If I place my LR speakers inside the frame of my 120" screen, then the door consumes my FRP, but if I place my speakers outside the screen frame, I could get some panels mounted... but the speakers would be very close to the side wall.

Any thoughts out there?

Thank you.


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## BIGmouthinDC

bfb1963 said:


> I was going to do a double door, but with the way it would open to the inside, I could never get any wall treatments where the door would swing against, nor could I place door mounted treatment. I am going to ditch the double door, and just use a massive outside door with acoustic sweeps.


For an in-swinging door you need to discover wide throw hinges that move the pivot point flush with the treatments.


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## bfb1963

BIGmouthinDC said:


> For an in-swinging door you need to discover wide throw hinges that move the pivot point flush with the treatments.


Thanks for your input. I know about these, but I was hoping to get thicker acoustic treatment than 2" for my first reflection point (which means 4" of extra wide throw clearance to account for door and wall ). I could also just extend the jamb more into the room.


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## vollans

Hi,

We've recently bought a house that we're wanting to turn into a home cinema. The previous owners who built the house had intended to do that as well, but never quite got round to it with everything else in the house. Along with everything else, we're working out what to do with the acoustic treatments, especially with a bit at the front of the room (left on the drawing), and it has us stumped! 

They built these weird full height walls that stick out from the main wall about 18" and are about 3' wide. So the left and right speakers will need to sit somewhere around where these little alcoves are - I assume in front of them, rather than inside them, but I'm open to input. I would also assume bass traps in the main corners would help, but what about where these weird little walls are? Should they have bass traps on them as well? And if so, both sides of them? 

And if the projector screen part of the wall is protected by these walls so really only the centre speaker is definitely there (haven't worked out exactly where to put the subwoofers yet) would that whole wall need treatment still?


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## drunkpenguin

Looks like a good candidate for a false wall and an AT screen to me. You could put the center behind the screen in the center and put the speakers behind acoustically transparent fabric on the sides.


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## Ladeback

I agree with @drunkpenguin and you might want to move the rear height speakers back a little more toward the back row to get a little more separation.


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## vollans

drunkpenguin said:


> Looks like a good candidate for a false wall and an AT screen to me.


I was worried about the screen being too big for the distance you're watching from. A 100" 16:9 would fit nicely on the pillars, I wasn't sure if going much bigger would result in too big an image to be comfortable. It would be a very easy job to make a false wall, I agree. I'll have a chat with my builder...


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## vollans

Ladeback said:


> I agree with @drunkpenguin and you might want to move the rear height speakers back a little more toward the back row to get a little more separation.


I'm starting to think I might need to create a separate thread to avoid hijacking this one. I'd spent some time time reading the various Atmos threads and surround threads, and done the calculations and those positions seemed to be where it suggested was ideal. I would have intuitively put them further back as well, but thought "what do I know?". Nothing has been installed yet, so it's definitely not too late!


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## vollans

Not sure if this helps with what I'm facing, but this is the basic room at the moment, as my Anthem sees it, with no real setup or tuning, and no acoustic treatments (unless you count it has a carpet and a thick curtain...)


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## Ladeback

vollans said:


> I'm starting to think I might need to create a separate thread to avoid hijacking this one. I'd spent some time time reading the various Atmos threads and surround threads, and done the calculations and those positions seemed to be where it suggested was ideal. I would have intuitively put them further back as well, but thought "what do I know?". Nothing has been installed yet, so it's definitely not too late!


This looks better then the other one IMO. I take it you want the front row to be where the MLP to be? I see you can't move the the side surrounds up because of the window on the right side and that is to bad but should be ok.

I take it you are going from this?

https://www.dolby.com/us/en/guide/dolby-atmos-speaker-setup/7-1-4-setups.html

You may want to post in the Dolby Atmos thread as well.


----------



## Blue

I have 30” wide by 7” deep corner spaces up front to the sides of my L & R speaker boxes, which are toed-in. See the attached picture. I’ve been thinking about putting pink fluffy insulation from floor to ceiling in those spots as bass traps. Is this a good or bad idea?


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## HopefulFred

Blue said:


> Is this a good or bad idea?


This is a good idea.


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## vollans

Ladeback said:


> This looks better then the other one IMO. I take it you want the front row to be where the MLP to be?


Yes, that's the idea. The rear row will rarely be used in reality. 



> I see you can't move the the side surrounds up because of the window on the right side and that is to bad but should be ok.


Yup, the window is a pain for placement, so having to make the best of a bad thing. It had two really thick close-weaved curtains already, so I'm hoping that that at least will stop the glass being too much of a problem. 



> I take it you are going from this?
> 
> https://www.dolby.com/us/en/guide/dolby-atmos-speaker-setup/7-1-4-setups.html


Yes, that was my starting point, and someone (I forget who) posted on the thread you mentioned a spreadsheet for calculating minimum and maximum distances for placements of the atmos speakers. I figure if I'm starting pretty much from scratch I may as well get it right, especially as I've been "allowed" this room as my plaything. Though it hasn't stopped him from sighing and tutting at the idea of acoustic treatments.


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## Blue

HopefulFred said:


> This is a good idea.


How do you recommend getting a clean face on the floor to ceiling insulation in the corners? I assume the insulation covered in black speaker cloth will look lumpy. 

I was thinking about maybe using black privacy lattice from Home Depot just to make it easy. Will the little diamond shaped openings in the lattice provide enough space for the best bass wave absorption, or is it better to have it more open? If the latter, I could build a frame with much larger openings (with the speaker cloth stretched across them, of course. That takes a little more effort, but I can certainly go that route if it's preferable. 

I also thought about not worrying about how smooth the face looks and hanging big movie style curtains in the corners to hide it. I hate to put red up by my screen though. The room is really dark right now, with flat deep navy walls and ceilings and flat black trim.


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## drunkpenguin

Curtains come in lots of colors. Not just red.


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## HopefulFred

You've got a few options for how to get batts of insulation into large spaces like that. You could stack them, but as you noted they will compress and fall over and generally be a mess. Some racking or shelves could be used to support them - the lattice you're talking about would be fine for this. You could also hang them vertically from the ceiling. This is what I did (in a much smaller space - only 4 feet high) - I used a paper-backed roll cut to length and used plumbers strap run through the batt near the top to hang it. It's not a neat solution, but effective.

Neatness for this type of thing is important, since you will be looking at it all the time, and you probably want to contain any loose fibers for the sake of your air quality. In your situation, I would get some finger-joined pine or rip some 2x4 down to half-size and build a frame to use like a floor-to-ceiling door - essentially a small wall. Wrap the frame in the fabric of your choice (acoustic transparency is a very low concern for bass traps) and either wedge, velcro, or brad nail the wrapped frame in place to conceal that whole area.


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## mikela

Blue said:


> How do you recommend getting a clean face on the floor to ceiling insulation in the corners? I assume the insulation covered in black speaker cloth will look lumpy.


Here's what I did. Worked perfectly. If you use this method make sure and secure the slats to the 1x4's on the wall with screws to prevent the horizontal slats from sliding off.


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## Blue

HopefulFred said:


> You've got a few options for how to get batts of insulation into large spaces like that. You could stack them, but as you noted they will compress and fall over and generally be a mess. Some racking or shelves could be used to support them - the lattice you're talking about would be fine for this. You could also hang them vertically from the ceiling. This is what I did (in a much smaller space - only 4 feet high) - I used a paper-backed roll cut to length and used plumbers strap run through the batt near the top to hang it. It's not a neat solution, but effective.
> 
> Neatness for this type of thing is important, since you will be looking at it all the time, and you probably want to contain any loose fibers for the sake of your air quality. In your situation, I would get some finger-joined pine or rip some 2x4 down to half-size and build a frame to use like a floor-to-ceiling door - essentially a small wall. Wrap the frame in the fabric of your choice (acoustic transparency is a very low concern for bass traps) and either wedge, velcro, or brad nail the wrapped frame in place to conceal that whole area.


It would be much easier to hang insulation than to stack it. Is there any downside to hanging long pieces in terms of its effectiveness as a bass trap?


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## Blue

drunkpenguin said:


> Curtains come in lots of colors. Not just red.


Good point. I had red stuck on the brain because that's how I remember the old style theaters from when I was a kid. Maybe I'll hang black curtains up front to hide the bass traps.


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## Blue

I have 1" Knauf duct liner to put on the front wall of my theater. What type of plastic sheet should I put between the two layers of duct liner? I had 3 mil in my head. I'm not sure why, although I assume I read it in one of the threads at some point. However, recently in my build thread, someone said that he thought @BIGmouthinDC had recommended 6 mil.


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## HopefulFred

Blue said:


> Is there any downside to hanging long pieces in terms of its effectiveness as a bass trap?


No, I would try to fill the area in general; it will be tougher to have the whole space "filled" if it's hanging. Keep in mind that the portions tightest into the corners are the least effective for bass absorption, so make sure the are is filled, but don't stress about the deep dark corners. The thing that's the most important, from a practical standpoint (IMO) is hanging them in a durable way - you won't want to mess with them once they're up, and if you futz with them you'll be likely to tear them loose.


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## mikela

Blue said:


> It would be much easier to hang insulation than to stack it.


Not really


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## ncabw

Can I make corner bass traps that are square? I only have 16” from edge of my screen to side wall. So I was thinking of just making a 12”x12” box 9’ high and stick in the 2 front corners. Or would it be better to make a small triangle? Or even an odd shape triangle. Maybe something like. 12x24 










Also I want to make ceiling panels. Does it matter which way I run them between the Lights? 
And again should I make the panel above the screen on a angle like a bass trap? 











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## ereed

ncabw said:


> Can I make corner bass traps that are square? I only have 16” from edge of my screen to side wall. So I was thinking of just making a 12”x12” box 9’ high and stick in the 2 front corners. Or would it be better to make a small triangle? Or even an odd shape triangle. Maybe something like. 12x24
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Also I want to make ceiling panels. Does it matter which way I run them between the Lights?
> And again should I make the panel above the screen on a angle like a bass trap?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk


If you do not want to go DIY just go to gik acoustics website. They have square/cube as well as triangle corner bass traps.


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## nonstopdoc1

Do acoustic absorption wall panels eg Roxul AFB pr Corning Fiber Glass need to be covered by acoustic fabric like GOM FR701 or can be any fabric?


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## Livin

nonstopdoc1 said:


> Do acoustic absorption wall panels eg Roxul AFB pr Corning Fiber Glass need to be covered by acoustic fabric like GOM FR701 or can be any fabric?


Anything you can see light through works fine. I used cheap black material from Walmart that had an interesting texture/weave.

Sent from my SM-G950U using Tapatalk


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## Blue

Blue said:


> I have 1" Knauf duct liner to put on the front wall of my theater. What type of plastic sheet should I put between the two layers of duct liner? I had 3 mil in my head. I'm not sure why, although I assume I read it in one of the threads at some point. However, recently in my build thread, someone said that he thought @BIGmouthinDC had recommended 6 mil.


I'm going to hang the duct liner on the front wall in a couple days. Does anyone have any thoughts on what plastic to use? I found an old post where Jeff said use anything from 3 to 5 mil. I couldn't find 5 mil at home depot, so right now I have a roll of 4 mil ready to go up. 

Also, what's the best way to attach two layers of duct liner sandwiching a layer of plastic onto a wall of double drywall? Right now, I have long relatively thick screws that I'm planning to use, which will sink a good distance into the double drywall without going all of the way through. I have been assuming that I don't need to use long drywall anchors that would puncture through my soundproofing.


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## mikela

Blue said:


> Also, what's the best way to attach two layers of duct liner sandwiching a layer of plastic onto a wall of double drywall?


This is what Jeff @BIGmouthinDC recommended awhile back.


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## Mahuzz13

Regarding 6mil poly for my front baffle wall do you put 1” linacoustic then poly then another 1” linacoustic? 

Please explain the benefits of this please. If it is good for the baffle wall do you use it around your room if you are fabric walls with 2” linacoustic behind the fabric. 

Thanks for your help 


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## Blue

Mahuzz13 said:


> Regarding 6mil poly for my front baffle wall do you put 1” linacoustic then poly then another 1” linacoustic?
> 
> Please explain the benefits of this please. If it is good for the baffle wall do you use it around your room if you are fabric walls with 2” linacoustic behind the fabric.
> 
> Thanks for your help
> 
> 
> Sent from my iPhone using Tapatalk


According to Jeff ( @BIGmouthinDC ) in other threads, including the one @mikela linked a couple posts above this one, the plastic goes in between the two layers of duct liner, and it increases low frequency absorption. 

I'm no expert, but I've read warnings about not overtreating a room to the point that it becomes too dead. I would be worried that putting 1"/plastic/1" all around the room would be too much. In my searches and reading, I don't recall seeing anyone do that. 

I'm still stumped on what thickness of plastic to use. I've seen anywhere from 3 mil to 6 mil discussed, but can't seem to find any posts to confirm what the current recommendation is with respect to which thickness yields the best results.


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## Mahuzz13

Thanks Blue
I’ve only seen 6mil and I think using either or you will get benefits rather than not using anything. 
I have never seen measurements done by anyone that shows the difference of having it and not having it. 


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## Blue

Is there a primer out there for treating a room with panels? I have 1" duct liner/plastic/1" duct liner on the front wall. I haven't done anything else yet. What are the core basics for treating the back wall, side walls and ceiling? It seems like the various threads involve so many different approaches. It makes it hard to know where to start.


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## sdurani

Blue said:


> What are the core basics for treating the back wall, side walls and ceiling?


Even in this day and age of surround sound, the front soundstage remains critical: that's where your attention will be focused, whether listening to music or watching a movie. With that in mind, I would start by covering most of the front wall (at least between the L/R speakers) with broadband absorption to keep reflections from muddying the front soundstage. I'd do the same with the middle half to third of the back wall (directly opposite centre speaker), for the same reason. Side wall treatment is up to your personal preference: those reflections are outside the soundstage and lateral (sideways moving) sounds tends to increase spaciousness. If you're doing height speakers, then broadband absorption on the ceiling can improve separation between sounds around you vs sounds above you. If you're not doing heights, then I would do little to no absorption on the ceiling (don't want to kill the bubble). That's my core basics for treatments. Beyond that, experiment and find out what sounds good to you.


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## Blue

sdurani said:


> Even in this day and age of surround sound, the front soundstage remains critical: that's where your attention will be focused, whether listening to music or watching a movie. With that in mind, I would start by covering most of the front wall (at least between the L/R speakers) with broadband absorption to keep reflections from muddying the front soundstage. I'd do the same with the middle half to third of the back wall (directly opposite centre speaker), for the same reason. Side wall treatment is up to your personal preference: those reflections are outside the soundstage and lateral (sideways moving) sounds tends to increase spaciousness. If you're doing height speakers, then broadband absorption on the ceiling can improve separation between sounds around you vs sounds above you. If you're not doing heights, then I would do little to no absorption on the ceiling (don't want to kill the bubble). That's my core basics for treatments. Beyond that, experiment and find out what sounds good to you.


Thanks. I have Atmos speakers. What qualifies as "broadband absorption"? How much of the ceiling should I treat?


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## sdurani

Blue said:


> What qualifies as "broadband absorption"?


Absorption down to 200Hz, even 100Hz if you can (4"-6" of rigid fiberglass). Panels that are too thin end up absorbing only the higher frequencies, acting like a tone control (like turning the treble knob down).


> How much of the ceiling should I treat?


First reflection points of the L/C/R speakers. Probably don't need much more than that.


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## Blue

sdurani said:


> Absorption down to 200Hz, even 100Hz if you can (4"-6" of rigid fiberglass). Panels that are too thin end up absorbing only the higher frequencies, acting like a tone control (like turning the treble knob down). First reflection points of the L/C/R speakers. Probably don't need much more than that.


I used 1" duct liner / plastic sheet / 1" duct liner on most of the front wall after reading through various threads. Is that broadband absorption?

Do the panels people make at home with 2" of rigid insulation and a 2" air gap qualify as broadband absorption? Or is it better to have 4" of insultation instead? Are there off the shelf products you recommend for broadband absorption if I decide not to take on yet another DIY project in my theater room?

Thanks again.


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## jcmccorm

Hey guys, quick question (I think). I've been running REW SPL sweeps in my room and I've got some uneven response. The frequencies from around 80Hz to 700Hz are almost 10db higher than everything above that (which is pretty flat up to 20KHz). It's particularly bad for the center channel. I'm thinking that I need better low frequency absorption and I'm wondering what the best way to achieve that is.


I have treated the first reflection points and the front wall behind the speakers. The ceiling as 4" 703 with a 6" gap. The sloped ceiling has 2" 703 with a 1/2" gap. The sides have 4" 703 with a 1/2" gap. Behind the speakers is 4" 703 with a 1/2" gap. Here's a picture of the room.












Here's a graph of the center channel.












The left and right speakers actually aren't that bad.
I'm thinking that either I can...
1) Increase the effectiveness of my absorption to include absorption of lower frequencies, or...
2) I'll have to resolve myself that the placement of the speakers near the floor and a wall is the culprit and I'll have to EQ it out. It may work to my disadvantage that the center speaker is equidistant from the ceiling and the center of the both sloped ceiling sides (may or not be an issue, not sure).


Anyway, if anyone has any advice on taking down some of this mid frequency stuff or maybe advice on more effective absorption, I'd be most appreciative. Thanks!


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## ereed

jcmccorm said:


> Hey guys, quick question (I think). I've been running REW SPL sweeps in my room and I've got some uneven response. The frequencies from around 80Hz to 700Hz are almost 10db higher than everything above that (which is pretty flat up to 20KHz). It's particularly bad for the center channel. I'm thinking that I need better low frequency absorption and I'm wondering what the best way to achieve that is.
> 
> 
> I have treated the first reflection points and the front wall behind the speakers. The ceiling as 4" 703 with a 6" gap. The sloped ceiling has 2" 703 with a 1/2" gap. The sides have 4" 703 with a 1/2" gap. Behind the speakers is 4" 703 with a 1/2" gap. Here's a picture of the room.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Here's a graph of the center channel.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The left and right speakers actually aren't that bad.
> I'm thinking that either I can...
> 1) Increase the effectiveness of my absorption to include absorption of lower frequencies, or...
> 2) I'll have to resolve myself that the placement of the speakers near the floor and a wall is the culprit and I'll have to EQ it out. It may work to my disadvantage that the center speaker is equidistant from the ceiling and the center of the both sloped ceiling sides (may or not be an issue, not sure).
> 
> 
> Anyway, if anyone has any advice on taking down some of this mid frequency stuff or maybe advice on more effective absorption, I'd be most appreciative. Thanks!


Good looking room! I'd check out GIK acoustics and put tri corner traps on the front corners. Also I can't tell in the pic but is the center speaker angled up at all? It could be floor bounce and angling it up will reduce some of it. Also maybe put a thick rug pad underneath your rug...the thicker the better!


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## jcmccorm

ereed said:


> Good looking room! I'd check out GIK acoustics and put tri corner traps on the front corners. Also I can't tell in the pic but is the center speaker angled up at all? It could be floor bounce and angling it up will reduce some of it. Also maybe put a thick rug pad underneath your rug...the thicker the better!


Thank you for responding! Yes, it's hard to tell since I used a wide angle on that photo but the center speaker is tilted up towards the MLP. I suspected floor bounce and layed a 4.5"x96" bat of Ultratouch on the floor between the center speaker and the MLP (where the mic is) and it barely altered the SPL graph. I do plan on getting a rug pad to put under the rug.

Thank you for the suggestion on the corner traps. I started thinking the same thing and was researching corner traps this morning. I was thinking of putting them in the side corners, then along each side of on the sloped ceiling against the front wall, and then at the top ceiling against the front wall. It can't hurt (and honestly, room treatments, I've found, are the cheapest audio upgrades for what you get out of them).

What do you think about the existing side treatments? The ceiling cloud is good I think - 4" 703 with 6" gap. I was thinking of putting a gap between the side walls and those 4" panels and then replacing the 2" panels on the sloped ceiling with 4" panels with a gap. Lots of work to do that and I don't have a feel for whether or not it would do anything (this is the first room I've ever treated).

Thanks again!


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## sdurani

Blue said:


> I used 1" duct liner / plastic sheet / 1" duct liner on most of the front wall after reading through various threads. Is that broadband absorption?


Haven't heard of that particular sandwich but I'm guessing not. Do the various threads you've read about it describe it as broadband?


> Do the panels people make at home with 2" of rigid insulation and a 2" air gap qualify as broadband absorption? Or is it better to have 4" of insultation instead?


4" with a 4" air gap or 6" on the wall. See absorption coefficients for various materials & thicknesses: http://www.bobgolds.com/AbsorptionCoefficients.htm


> Are there off the shelf products you recommend for broadband absorption if I decide not to take on yet another DIY project in my theater room?


Check out websites for GIK Acoustics, Auralex, Primacoustics, Next Generation Acoustics, etc.


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## ereed

jcmccorm said:


> Thank you for responding! Yes, it's hard to tell since I used a wide angle on that photo but the center speaker is tilted up towards the MLP. I suspected floor bounce and layed a 4.5"x96" bat of Ultratouch on the floor between the center speaker and the MLP (where the mic is) and it barely altered the SPL graph. I do plan on getting a rug pad to put under the rug.
> 
> Thank you for the suggestion on the corner traps. I started thinking the same thing and was researching corner traps this morning. I was thinking of putting them in the side corners, then along each side of on the sloped ceiling against the front wall, and then at the top ceiling against the front wall. It can't hurt (and honestly, room treatments, I've found, are the cheapest audio upgrades for what you get out of them).
> 
> What do you think about the existing side treatments? The ceiling cloud is good I think - 4" 703 with 6" gap. I was thinking of putting a gap between the side walls and those 4" panels and then replacing the 2" panels on the sloped ceiling with 4" panels with a gap. Lots of work to do that and I don't have a feel for whether or not it would do anything (this is the first room I've ever treated).
> 
> Thanks again!


I think your did well with the ceiling panels. I'm not aware of how well DIY products work or know much about them cause I haven't used it. I know GIK also sells those products and they will even answer your question about your DIY build even if you are not purchasing GIK. That's what I like about them....they give helpful free advice and I would ask them. But I do know that if you add air gap or mount the panels 2 inches off the wall it will increase lower absorption. How much? Not sure.

And yes, room treatments are the secret hidden gem and probably best bang for your buck in helping sound more than anything.


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## mhutchins

You might try replacing the 703 in your absorbers with pink fluffy fiberglass. It is supposed to do better in the lower frequencies than the rigid panels. It is discussed here.

Mike


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## jcmccorm

mhutchins said:


> You might try replacing the 703 in your absorbers with pink fluffy fiberglass. It is supposed to do better in the lower frequencies than the rigid panels. It is discussed here.
> 
> Mike


Thank you! I'll read it now. Complete replacement or mix of 703 and fluffy?

What about the 6" of 703 against the wall shown in this link (that I know we've all seen)?

https://www.bobgolds.com/AbsorptionCoefficients.htm

I guess I'll go read


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## Blue

sdurani said:


> Haven't heard of that particular sandwich but I'm guessing not. Do the various threads you've read about it describe it as broadband? 4" with a 4" air gap or 6" on the wall. See absorption coefficients for various materials & thicknesses: http://www.bobgolds.com/AbsorptionCoefficients.htm Check out websites for GIK Acoustics, Auralex, Primacoustics, Next Generation Acoustics, etc.


I guess it's just different advice from a different school of thought. The duct liner/plastic sheet/duct liner sandwich is frequently discussed on these boards, including in this thread. I hope it works because it's done now. 

6" is too deep for my back wall. We don't have the space to spare. I could do 4" at most. Hopefully GIK has something thinner that's still broadband for the back wall and ceiling. 

Thanks again for your help.

Update: These are less than 4" thick. Are they considered broadband? http://www.gikacoustics.com/product/gik-acoustics-242-acoustic-panel/


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## sdurani

Blue said:


> These are less than 4" thick. Are they considered broadband? http://www.gikacoustics.com/product/gik-acoustics-242-acoustic-panel/


What does the manufacturer say about their absorption range?


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## Blue

sdurani said:


> What does the manufacturer say about their absorption range?


The website calls it broadband in passing in the description. Here are the test results, which probably make more sense to you than me:

http://static.gikacoustics.com/wp-c...242-Acoustic-Panel-absorption-coefficient.jpg

http://static.gikacoustics.com/wp-c...242-Acoustic-Panel-additional-frequencies.jpg


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## sdurani

Blue said:


> The website calls it broadband in passing in the description.


Close enough (since you can't do 6" panels anyway).


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## bafflesteppe

Wow, there's some beautiful setups in this thread. Practical and proven, as well. I'm hoping to get close.

Can you guys help point me in the right direction? I've got a good start.

My build thread is here: https://www.avsforum.com/forum/15-g...me-rooms/2958434-bafflesteppe-sound-room.html

I have a 32' long, 12.5' wide basement theater/jam room I'm trying to treat. Unfortunately, I have 7' tall ceilings, and it's lower in places due to AC ducting. It's a cement floor with a thin carpet (big shag rug in listening area) and cinder block walls—so a bunch of hard surfaces all around.

I've started with ten 48x16x3" Roxul Safe'n'Sound acoustic panels all around the theater side. My plan is to space out 20 acoustic panels (with movie/music prints) on the side walls, and do a combination of acoustic panels and diffusers—skyline, parametric?—on the front and rear walls. Large acoustic cloud panel on the ceiling at the first reflection point. Corner bass traps all around.

That picture attached should say 5.2.2, not 7.2.2. I don't think I have that much room.

How's that looking?

My build thread also has measurements of the room. Thanks guys.


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## ScottieBoysName

LydMekk said:


> Whole front wall, corner to corner. I even treated the first 80cm out from the front corners on the side walls.
> See my thread in my signature, pictures of the process.


What did you cover the linacoustic with for a finished look?


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## ScottieBoysName

corradizo said:


> Hi Guys,
> 
> This is what is behind my screen.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This is how I've treated it with r19 OC Batts.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Is this an acceptable approach? My screen is AT and their will be panels made of syfabrics triple black Velvet around it.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Thanks,
> 
> Pete


I'm thinking of doing the same thing. Is this acceptable to everyone?


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## corradizo

I just need to put the curtains on the sides yet.


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## ScottieBoysName

corradizo said:


> I just need to put the curtains on the sides yet.


Can you give me some details on what you did there?


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## corradizo

ScottieBoysName said:


> Can you give me some details on what you did there?



Here are some pics. I sawed 2x4's down to make 1.5" x 1.5" stock. I used pocket screws and glue to make up the frames. Used whatever black paint I had to paint them. I engineered a little door to access equipment in the bottom panel. The panel s are just covered with joann fabrics velvet and stapled. The top panel just fits with friction and I may put Velcro up at the top if it moves. The bottom panel would not stand on its own so I made feet so it can wedge under the subs but also be removable.


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## ScottieBoysName

Got it! Thank you!!


----------



## cheyne2525

*Room Treatment / Acoustically friendly materials for cabinetry*

Hey everyone. I have intermittently frequented some of the other threads on AVS and i'm back once again for some more of the excellent advice that i usually get here, so feel free to pile on!
I'm sorry if this post is a little long winded (i have a slight touch of OCD, lol) but I am redoing the front wall of my semi-dedicated home theater area and i wanted to run this by all of the experienced peeps here, my plan is as follows: 

1. I want to treat the front room corners w/ 2 bass tri-traps each and then maybe also put 6-inch thick panel bass traps mounted up in the trihedral corners where the ceiling meets the room corners.

2. I'll be adding additional acoustic panels at other key points (mostly absorption but with some limited diffusion ability) to the setup's 2 existing DIY cotton-based broadband absorption panels that i placed for the 1st reflections. I want to keep the front sound-stage as neutral as i can but without going overboard and deadening the room's sound too much; it's already much less reverberant than it was when i first started the process.

3. Depending on which way i decide to place/mount them, the back wall will get treated with either 3 or 5 six-inch thick GiK acoustic panels of varying sizes w/ scatter plates inside them to keep the room lively.

4. I think that adding one tube trap (a 16-inch ASC full round, only 1 can be done due to them being a lil pricy for me) to the back left corner of the room would be beneficial since it is an obvious area of bass buildup. I would be open to using other traps if the tube trap isn't ideal for an area outside the main listening zone or if another trap would be better suited. 
The room's rear right side corner is a no-go for any bass traps due to the high volume of traffic going through the door located there, but it shouldn't be too bad considering how the room is laid out - it opens up quite a bit on the back right side of the room (GiK reps said that it may help to give bass freq.'s a place to go instead of pooling up in a room mode) whereas the entire left side has a wall running the whole length.

Now, the MAIN reason I'm posting here today is to get some direction on where to go with my upcoming cabinetry build for the front wall area of the HT. 
The house I moved into had a den that was great for what i wanted but the front wall was covered in some customer cabinetry the prev. owners had put in. It was nice and i was able to adapt it to my purposes for the first couple of yrs, but now, as my acoustic knowledge has grown and I've learned more, i knew that it would need to be seriously altered or replaced to meet my acoustic criteria. 

The time has come now to undertake the project (which will change the room and that just thrills my wife... ) and I'm almost ready to submit my ideas for the cabinetry re-design to the carpenter i'm working with. So...my big Q is, what kind of material could i work with that would have minimal disruption to my sound? 
KBarnes told me that having solid wood cabinetry (or any hard reflective surface for sound to bounce off of) w/ shelving bays will degrade the audio clarity and sound-stage imaging to some degree, so I've been trying to determine if there is a solid enough material i could use to construct an entertainment stand w/ additional shelving that would be acoustically camouflaged or at least somewhat non-reflective. 
I have researched various things i could add/attach to traditional wood as well as actual acoustic panel material that's strong enough to build things with and my best candidates are as follows:

A. Add-on items
1. https://www.acousticalsurfaces.com/sound_silencer/dBA_panel.htm
2. https://www.acousticalsurfaces.com/sound_silencer/sswall_panel.htm?d=2
3. https://www.acousticgeometry.com/products/aco-u-stick/
4. https://www.aixfoam.com/absorption-panel-sh001-plain

B. Possible construction materials
1. http://www.neatconcepts.com/neatsonic.htm
2. https://www.soundply.com/structure/
3. https://www.acousticalsurfaces.com/envirocoustic-woodwool/
4. https://kireiusa.com/products/kirei-board
5. https://www.alibaba.com/product-detail/bamboo-particle-board_1737469888.html? 
spm=a2700.7724857.normalList.41.6a0b6c2eB6e8y1
6. https://acousticalsolutions.com/product/polyphon-polyester-acoustic-panels/

In addition to the above links, i am including a PDF link w/ the absorption specs for perforated MDF since i had also considered MDF as a possible material and it was surprisingly informative. I'm also including a link that i came across for some designer that creates furniture from acoustic paneling, i though it was quite the novel idea and am trying to replicate it with my cabinetry, just with a different looking design.

- -http://www.elliotbastianon.com/six-fold

- https://decorsystems.com.au/app/uploads/2017/02/DecorTrend-by-Decor-Systems- 
Acoustic-Data.pdf


I had seen in some other threads where people would make frames and then use stiff acoustic panels for the walls, shelving, doors, etc. to turn it into a cabinet or entertainment center, which is what i think i want here but i don't want to over absorb the sound in the front half of the room.
As always, I'm looking forward to hearing what everyone has to say and I hope that someone thinks of something that i either missed or maybe didn't know. Since this cabinetry build hasn't started yet I am open to suggestions on what potential designs would be most beneficial. I included some older pics of the room for reference but it has changed some since they were taken.


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## Jim Kiler

Advice needed. If i have an L shaped room and i am getting bass that bounces between an end wall and fireplace wall, a 3 foot section, would a diffuser help move the bass out of this small area. This is occuring in the section that is away from the TV and i could leave it but if I could move the bass back into the rest of the room it would be louder. Would a bass trap work or would a bass trap reduce the amount of bass. I did some reading and am unsure still. I cannot get wife approval for a bass trap that sticks out so it has to be something hanging on the wall. Actually my wife is already against that because it would be so close to the bookcase but i will get her to come around. Any advice would be greatly appreciated. I have a SVS 2000 sub which i love but i can always use more bass where i sit so i don't want to take away bass from the room.


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## ereed

Jim Kiler said:


> Advice needed. If i have an L shaped room and i am getting bass that bounces between an end wall and fireplace wall, a 3 foot section, would a diffuser help move the bass out of this small area. This is occuring in the section that is away from the TV and i could leave it but if I could move the bass back into the rest of the room it would be louder. Would a bass trap work or would a bass trap reduce the amount of bass. I did some reading and am unsure still. I cannot get wife approval for a bass trap that sticks out so it has to be something hanging on the wall. Actually my wife is already against that because it would be so close to the bookcase but i will get her to come around. Any advice would be greatly appreciated. I have a SVS 2000 sub which i love but i can always use more bass where i sit so i don't want to take away bass from the room.


Bass waves travel on length based on frequency. So a low freq bass note will hit the front and back wall and other walls around it many times. You need bass traps on both ends of walls to keep it from bouncing. The more you have the better, but even a thick panel you put on wall is better than nothing. Look up GIK monster bass traps or 244 panels for wall mounting.


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## Jim Kiler

ereed said:


> Bass waves travel on length based on frequency. So a low freq bass note will hit the front and back wall and other walls around it many times. You need bass traps on both ends of walls to keep it from bouncing. The more you have the better, but even a thick panel you put on wall is better than nothing. Look up GIK monster bass traps or 244 panels for wall mounting.


thanks for the help. Will bass traps reduce the level of my bass? Or will is sound louder since I will be able to hear the other bass levels or is it a guessing game since i have no idea what frequencies are resonating?


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## Jim Kiler

ereed said:


> Bass waves travel on length based on frequency. So a low freq bass note will hit the front and back wall and other walls around it many times. You need bass traps on both ends of walls to keep it from bouncing. The more you have the better, but even a thick panel you put on wall is better than nothing. Look up GIK monster bass traps or 244 panels for wall mounting.


thanks for the help. Will bass traps reduce the level of my bass? Or will is sound louder since I will be able to hear the other bass levels or is it a guessing game since i have no idea what frequencies are resonating?

I will check both those options out.


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## ereed

Jim Kiler said:


> thanks for the help. Will bass traps reduce the level of my bass? Or will is sound louder since I will be able to hear the other bass levels or is it a guessing game since i have no idea what frequencies are resonating?
> 
> I will check both those options out.


No it will not reduce bass levels, it will just help smooth out bass peaks and nulls in the room and improve decay times and sound overall better. If you want to reduce bass from going to other rooms you need to sound proof the room, but that is not what bass traps are for.


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## Jim Kiler

ereed said:


> No it will not reduce bass levels, it will just help smooth out bass peaks and nulls in the room and improve decay times and sound overall better. If you want to reduce bass from going to other rooms you need to sound proof the room, but that is not what bass traps are for.


thanks again. I have roxul stone wool in the ceiling and lining my stairwell. The only other rooms are a bathroom and utility room so i am good from that standpoint. Thank you I will have to get a couple bass traps for this then.


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## tonybradley

Some advice needed.

I've had a very budget dedicated HT for about 14 years and just updated with a new PJ and bigger screen. I currently have 4" of Bass Traps (Knauf Rigid Fiberglass) in the front two corners and 2' x 4' Absorption Panels at the First Reflection Points using 2" of Knauf Rigid Fiberglass.

I recently ordered some Triple Velvet from Amazon to place on the side walls (about 6' out from the front wall) to help with the light reflection from the screen. My plan is to make Panels (similar to my absorption panels) at 2.25" deep and stack floor to ceiling (only 7'4" tall). I will place my Rigid Fiberglass behind the Velvet panel in the First Reflection spot. But the spot before that panel doesn't currently have absorption and just reflection on drywall. On another thread, when I was thinking of hanging Velvet Curtains on the side, I was told it would be better to attach the Velvet directly to the drywall to aid in reflection at that point. I don't want to adhere to the wall, which is why I'm making panels. I thought adding thin Plywood or luan to the front of frame prior to wrapping with velvet would help with reflection. I was told in that same thread that wouldn't be a good idea, and filling those panels with quilt batting would aid in passing the frequencies to the drywall for Absorption.

Would it be better have a 2.25" frame with Velvet and nothing behind it, plywood on the face of frame, or the batting in the frame to help with Reflection? I realize Velvet isn't the best thing to do here for Audio, but I have to compromise as right now, the light reflection in the room off the side walls, ceiling and floor are too much. My room sounds decent enough now with the Absorption at first reflection points and bass traps in front corners. I may make some for the back corners too, but they will partly cover my two Recessed Shelves on the back wall.

Thanks for any input on this.


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## ereed

tonybradley said:


> Some advice needed.
> 
> I've had a very budget dedicated HT for about 14 years and just updated with a new PJ and bigger screen. I currently have 4" of Bass Traps (Knauf Rigid Fiberglass) in the front two corners and 2' x 4' Absorption Panels at the First Reflection Points using 2" of Knauf Rigid Fiberglass.
> 
> I recently ordered some Triple Velvet from Amazon to place on the side walls (about 6' out from the front wall) to help with the light reflection from the screen. My plan is to make Panels (similar to my absorption panels) at 2.25" deep and stack floor to ceiling (only 7'4" tall). I will place my Rigid Fiberglass behind the Velvet panel in the First Reflection spot. But the spot before that panel doesn't currently have absorption and just reflection on drywall. On another thread, when I was thinking of hanging Velvet Curtains on the side, I was told it would be better to attach the Velvet directly to the drywall to aid in reflection at that point. I don't want to adhere to the wall, which is why I'm making panels. I thought adding thin Plywood or luan to the front of frame prior to wrapping with velvet would help with reflection. I was told in that same thread that wouldn't be a good idea, and filling those panels with quilt batting would aid in passing the frequencies to the drywall for Absorption.
> 
> Would it be better have a 2.25" frame with Velvet and nothing behind it, plywood on the face of frame, or the batting in the frame to help with Reflection? I realize Velvet isn't the best thing to do here for Audio, but I have to compromise as right now, the light reflection in the room off the side walls, ceiling and floor are too much. My room sounds decent enough now with the Absorption at first reflection points and bass traps in front corners. I may make some for the back corners too, but they will partly cover my two Recessed Shelves on the back wall.
> 
> Thanks for any input on this.


I would not cover your absorption panels with velvet, it will keep the panel from doing what its supposed to do. It would not affect low freq, but covering it with velvet will affect high/mid frequencies. Its best to put velvet around the panel and other places if you want a dark room, or choose a darker fabric for your panels, but they need to be acoustic pass thru fabric such as GOM fabric.


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## tonybradley

ereed said:


> I would not cover your absorption panels with velvet, it will keep the panel from doing what its supposed to do. It would not affect low freq, but covering it with velvet will affect high/mid frequencies. Its best to put velvet around the panel and other places if you want a dark room, or choose a darker fabric for your panels, but they need to be acoustic pass thru fabric such as GOM fabric.


Why would a broadband absorption panel need to be acoustically transparent? If it absorbs the highs prior to hitting the fiberglass, no big deal because the fiberglass will absorb it anyway. I see the only issue is if the Velvet is Reflective while covering a broadband absorption panel as it would reflect the highs, which I wouldn't want. But I've not been able to find any data if Triple Black Velvet will reflect the highs or absorb them prior to hitting my Rigid Fiberglass behind. If the latter, all good. If the former, not so good.


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## ereed

tonybradley said:


> Why would a broadband absorption panel need to be acoustically transparent? If it absorbs the highs prior to hitting the fiberglass, no big deal because the fiberglass will absorb it anyway. I see the only issue is if the Velvet is Reflective while covering a broadband absorption panel as it would reflect the highs, which I wouldn't want. But I've not been able to find any data if Triple Black Velvet will reflect the highs or absorb them prior to hitting my Rigid Fiberglass behind. If the latter, all good. If the former, not so good.


Not all velvet is acoustically transparent. There have been tests to prove it. I don't know which brand are or aren't, I just know that putting velvet over your panels may or may not change the sound of the room. Only way to know is to test it.


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## mtbdudex

Been a while since I cruised this thread ....

Did a search on HAA and Home Acoustics Alliance, nothing came up.

These 2 posts take acoutsic treatments into the late 2010's.
Lots of what I read here seems to be mid 2000's understanding.


*acoustical-treatment-primer-absorption
*
(read the article I linked above, snippet below)
Mirror Points

Sometime later, the benefits of absorbing the “mirror points” was discovered. This was a more complex concept as it required the use of a mirror and an assistant (or willing spouse) to move a mirror along the side walls until you could see each of the speakers. Each mirror point was then the target for placement of an absorptive panel. Most of the time the result was quite audible, producing a decided improvement in focus and detail. Diagram one shows the mirror (reflection) points as the sound travels like a billiard ball bouncing off the wall to your ear; these are called specular reflections. While audible, absorbing sound at all the mirror points or even just the side wall mirror points is not completely beneficial and causes other problems.












Today, we now know that simply absorbing all reflections is not the best choice. Some reflections should be absorbed yet others enhance envelopment and spaciousness. I like to call it reflection management. I’ll try to use our blog here to share some information about each treatments function but also on their best use in your room.

Treatment Types

The various enthusiast forums are replete with a variety of treatment strategies using any number of different designs. It can be confusing and costly if the result is not satisfactory. The most basic strategies can usually provide benefits, but it’s good to know a little about the science. First let’s look at the various types of treatment.

Absorption: Absorbing sound impacting the panel. It reduces or removes the energy of a reflection.
Diffusion: Diffusive panels scatter sound. While they are not generally designed to reduce the energy in sound they effectively reduce the energy in a reflection by dividing it into many reflections to various directions.
Reflection: Yes, reflection is an important element in room design. Many reflections are beneficial and should be preserved.
Bass traps: This category includes everything from very thick panels to diaphragmatic absorbers. The commonality is that they are most effective absorbing low frequencies.
Hybrid Treatments: These types combine the functions of the above types. They can be very useful when some frequencies should be absorbed while others reflected or scattered.
I’ll discuss each type in new blogs. Today, I’m writing about absorption.​

and this one next
*acoustical-treatment-primer-diffusion*

So, where do we place our diffusers? I’ll bow to the opinions of various acousticians out there by once again pointing out they seem to appear everywhere in some home theater designs. That’s not a bad thing. After all, we are seeking a more diffusive room. HAA recommends the best location for diffusors is in the rear half of the home theater, particularly between the surround and rear speakers. The audible effect is one of adding spaciousness to the sound. In addition, properly placed diffusors can reduce the localization of the surround and rear speakers; reduce the “exit door effect”. One location I do not like to used too much diffusion is on the side walls at the LCR reflections (mirror) points. While good diffusers do not reduce sonic energy (at least not much), they can reduce the energy of good reflections that we want. If I use diffusion on the LCR mirror points, I’ll still want plenty of the “good” reflections to be retained; just as I do when adding absorption there.







​


----------



## OJ Bartley

mtbdudex said:


>


This seems pretty similar to another post I saw that recommended a healthy mix of absorption and diffusion, with more absorption up front and more diffusion to the rear, including cloud treatments.

I know that the ideal way to proceed is to measure the untreated room and determine exactly what is needed, but that isn't always possible so I will likely dip my toe in and start with a strategy similar to the above, and see where that gets me.


----------



## Cscamp20

ScottieBoysName said:


> I'm thinking of doing the same thing. Is this acceptable to everyone?



Is this even safe? This is like asking for cancer with the insulation exposed. All for the sake of good sound.


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## ScottieBoysName

Cscamp20 said:


> Is this even safe? This is like asking for cancer with the insulation exposed? All for the sake of good sound.



I have no idea, I can't imagine it's THAT bad for you.


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## Skylinestar

What's the typical thickness of those insulation batts around the LCR speaker?
Photo for reference:


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## Soulburner

ereed said:


> No it will not reduce bass levels, it will just help smooth out bass peaks and nulls in the room and improve decay times and sound overall better. If you want to reduce bass from going to other rooms you need to sound proof the room, but that is not what bass traps are for.


And soundproofing can have negative effects on your quest to fight bass modes and decay.


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## Skylinestar

Soulburner said:


> And soundproofing can have negative effects on your quest to fight bass modes and decay.


How is that so? Kindly enlighten me.


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## ereed

Soulburner said:


> And soundproofing can have negative effects on your quest to fight bass modes and decay.


You still have bass modes and decay regardless if its soundproof room or not since the bass waves will bounce from one wall to another. Bass room modes are based on room dimensions. You would still need to treat the room regardless. The only thing beneficial to soundproof a room is 2 things....to keep sound going out and keep outside sound coming in the room. Soundproofing a room is different than sound absorbing a room alone....but the same logic applies to installing room treatments from both cases.


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## mikela

Double drywall with green glue on clips and channel (sound proofing) flexes and can provide a reduction in room modes.


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## Soulburner

Skylinestar said:


> How is that so? Kindly enlighten me.





ereed said:


> You still have bass modes and decay regardless if its soundproof room or not since the bass waves will bounce from one wall to another. Bass room modes are based on room dimensions. You would still need to treat the room regardless. The only thing beneficial to soundproof a room is 2 things....to keep sound going out and keep outside sound coming in the room. Soundproofing a room is different than sound absorbing a room alone....but the same logic applies to installing room treatments from both cases.


Of course, but not at all what I was talking about.

Start here, particularly the comments in paragraph 4:

https://www.avsforum.com/forum/19-dedicated-theater-design-construction/2734425-bass-traps-still-required-2017-home-theater.html#post50684857

And on the next page:

https://www.avsforum.com/forum/19-dedicated-theater-design-construction/2734425-bass-traps-still-required-2017-home-theater-2.html#post51003913

See what you think. I'm definitely not an expert on this stuff, but I don't doubt their findings.


----------



## ereed

Soulburner said:


> Of course, but not at all what I was talking about.
> 
> Start here, particularly the comments in paragraph 4:
> 
> https://www.avsforum.com/forum/19-dedicated-theater-design-construction/2734425-bass-traps-still-required-2017-home-theater.html#post50684857
> 
> And on the next page:
> 
> https://www.avsforum.com/forum/19-dedicated-theater-design-construction/2734425-bass-traps-still-required-2017-home-theater-2.html#post51003913
> 
> See what you think. I'm definitely not an expert on this stuff, but I don't doubt their findings.


I still don't get what you're trying to prove here. Care to explain in your own words?

Soundproofing the room the right way will have walls flexing and reduce room modes. Also people that properly soundproof their rooms also treat their rooms as well. So they get double the benefit!


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## Soulburner

Why would I bother to try to re-word everything in those posts? They clearly show that some construction methods to sound-proof a room have negative side-effects. So, use caution, that is all.


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## PrimeTime

ScottieBoysName said:


> I'm thinking of doing the same thing. Is this acceptable to everyone?



If you're going to use pink fluffy inside a room, a better approach would be to acquire it in shrinkwrapped rolls and stack them. First of all, the fiberglass will not be exposed to the air (or any handling). Second, as a shrinkwrapped roll the pink fluffy will perform better, as it will be in a compressed state that more closely matches the optimum density for absorbers (3-6 pounds per cubic foot).


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## ScottieBoysName

PrimeTime said:


> If you're going to use pink fluffy inside a room, a better approach would be to acquire it in shrinkwrapped rolls and stack them. First of all, the fiberglass will not be exposed to the air (or any handling). Second, as a shrinkwrapped roll the pink fluffy will perform better, as it will be in a compressed state that more closely matches the optimum density for absorbers (3-6 pounds per cubic foot).


Good point!


----------



## OJ Bartley

PrimeTime said:


> If you're going to use pink fluffy inside a room, a better approach would be to acquire it in shrinkwrapped rolls and stack them. First of all, the fiberglass will not be exposed to the air (or any handling). Second, as a shrinkwrapped roll the pink fluffy will perform better, as it will be in a compressed state that more closely matches the optimum density for absorbers (3-6 pounds per cubic foot).


I was wondering about that. Usually we see warnings not to compress the insulation, but maybe that's for more broadband traps. So would a compressed bag (no holes needed?) work better as a corner trap than the usual "stacked triangle" method?


----------



## PrimeTime

^^ Probably. For thermal insulation it's better to let them fluff out, but with sound absorption you're getting more insulation into a smaller space (better density). In any case, it's easy enough to test: just drive to the local Home Depot and load up as many rolls of R-13 ($13 a roll, last I checked) as you can. If you don't unwrap them, they can be returned as "excess material" later.


I'm a little leery about the whole concept of using insulation as "bass traps." I don't see much data on this application from the manufacturers, as their absorption coefficient data usually bottoms out at 125 Hz. However, improving the performance above, say, 100 Hz is still worthwhile. 

I'm an advocate of high absorption between you and your speakers, with little absorption everywhere else (a popular studio treatment approach). An excellent way to accomplish this in a dedicated A/V room is to remove the drywall near the speakers, fill the stud cavities with R-13 (R-19 with 2x6 studwalls in my case) and cover those surfaces with thin, dark indoor/outdoor carpeting. Drywall IMO is the single biggest obstacle to better sound in the home.


----------



## mikela

OJ Bartley said:


> I was wondering about that. Usually we see warnings not to compress the insulation, but maybe that's for more broadband traps. So would a compressed bag (no holes needed?) work better as a corner trap than the usual "stacked triangle" method?


Here is a Porous Absorption tool to give you a better idea about what compression of the insulation will do to absorption performance. My own experience with bagged insulation did not turn out well due to the amount it was compressed.


----------



## xpl0sive

Hi Guys,

My theater room has a window that I'm going to cover with a blind, but I want to shove some foam in the window cavity to reduce the negative affects of having a window in a theater. Can anyone recommend a product that would be suitable? is it best to just get the most dense foam available and put that in there?


----------



## asarose247

^ i built a frame, deep as the recess, flush out to the wall.
showing thru the windowside , to no one in particular, 3/16ths ply covered in a dark dray fabric.
since my frame was 3", I used 3.5" Roxul, some compaction, and closed up the frame with another piece of the the thin ply.

the frame was built to attain a good tight friction fit with the use of 3/8th foam weather stripping, primarily for total light blockage.

there were 2 windows so I just hung a big medium weight bedspread I got from BB&B, discounted.
fits my notion of decor and also helps with some room treatment aspects.

the packed frames can act somewhat as a bass and broadband absorber, tympanic membranes tech, if somewhat simplified.

my own research wrt foam, layman that I am, is that there really is no foam suitable for very much unless you're doing a studio . . 

and even then , in spite of so many youtube vids, 703 and Roxul are my go-tos

HTH


----------



## John M Miller

Hey everyone,

I'm finally getting around to treating my dedicated HT and I think I'm getting more confused the more I read about first reflection points. First the basics. My room is 12.5 x 18 with a cathedral ceiling. There's two rows of seats, the second on a 15" riser. I'm going to DIY my treatments with 48 x 24" absorbers and 24 x 24" skyline diffusers (if I do decide to diffuse).

Since I'm building this stuff in my very, very limited free time (I work 2 jobs and have 3 kids under 7) I'd like to formulate a 'good enough' plan and just do it. I want improvement, not perfection, so while it would be nice to measure, adjust, test, etc, that's just not going to happen.

So... I've read one view that there should be an anechoic path between the front speakers and the ear. But I've also read that it helps our brains locate the sound by having some ambient reflection. I don't (care to) understand the underlying science so to me it’s not clear. But is there some sort of consensus about a small-ish home theater environment like mine where the L/R channels are pretty close to the walls? To me it seems like mayyyybe the delay would be shorter so perhaps diffusion would be best there? Would a skyline diffuser even be appropriate in this use case? I chose that design because I can build it rather cheaply.

Any opinions greatly appreciated!


----------



## Soulburner

John M Miller said:


> Hey everyone,
> 
> I'm finally getting around to treating my dedicated HT and I think I'm getting more confused the more I read about first reflection points. First the basics. My room is 12.5 x 18 with a cathedral ceiling. There's two rows of seats, the second on a 15" riser. I'm going to DIY my treatments with 48 x 24" absorbers and 24 x 24" skyline diffusers (if I do decide to diffuse).
> 
> Since I'm building this stuff in my very, very limited free time (I work 2 jobs and have 3 kids under 7) I'd like to formulate a 'good enough' plan and just do it. I want improvement, not perfection, so while it would be nice to measure, adjust, test, etc, that's just not going to happen.
> 
> So... I've read one view that there should be an anechoic path between the front speakers and the ear. But I've also read that it helps our brains locate the sound by having some ambient reflection. I don't (care to) understand the underlying science so to me it’s not clear. But is there some sort of consensus about a small-ish home theater environment like mine where the L/R channels are pretty close to the walls? To me it seems like mayyyybe the delay would be shorter so perhaps diffusion would be best there? Would a skyline diffuser even be appropriate in this use case? I chose that design because I can build it rather cheaply.
> 
> Any opinions greatly appreciated!


It largely depends on what speakers you have. If you have speakers with an off-axis response that closely matches their on-axis response, keep most of the side reflections. If the off-axis performance is erratic, you don't want that sound reaching your ears and combining with the direct sound, because it has a different (and likely worse) character. So, absorb that sound. That may be oversimplifying, but it can be a general principle.


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## John M Miller

Soulburner said:


> It largely depends on what speakers you have. If you have speakers with an off-axis response that closely matches their on-axis response, keep most of the side reflections. If the off-axis performance is erratic, you don't want that sound reaching your ears and combining with the direct sound, because it has a different (and likely worse) character. So, absorb that sound. That may be oversimplifying, but it can be a general principle.


I have KEF LS50 speakers, which supposedly have great off-axis response. 
https://www.soundandvision.com/content/review-kef-ls50-speaker-page-2

So diffuse? Or do nothing at all at the first reflection points and worry more about bass trapping?


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## xpl0sive

asarose247 said:


> ^ i built a frame, deep as the recess, flush out to the wall.
> showing thru the windowside , to no one in particular, 3/16ths ply covered in a dark dray fabric.
> since my frame was 3", I used 3.5" Roxul, some compaction, and closed up the frame with another piece of the the thin ply.
> 
> the frame was built to attain a good tight friction fit with the use of 3/8th foam weather stripping, primarily for total light blockage.
> 
> there were 2 windows so I just hung a big medium weight bedspread I got from BB&B, discounted.
> fits my notion of decor and also helps with some room treatment aspects.
> 
> the packed frames can act somewhat as a bass and broadband absorber, tympanic membranes tech, if somewhat simplified.
> 
> my own research wrt foam, layman that I am, is that there really is no foam suitable for very much unless you're doing a studio . .
> 
> and even then , in spite of so many youtube vids, 703 and Roxul are my go-tos
> 
> HTH


Thanks. I was thinking of doing something similar as I have a spare bag of fibreglass insulation batts, but rather than frame out with ply I simply wanted to cover with fabric for health reasons, then shove it into the window frame. Would this work?


----------



## sdurani

John M Miller said:


> So diffuse? Or do nothing at all at the first reflection points and worry more about bass trapping?


With those Kef speakers, I wouldn't absorb (or diffuse) the near-wall first reflections. Instead, I would absorb the each speaker's first reflection on the far wall (contra-lateral reflections). This way, sounds intended for one side of the soundstage don't come at you (even subtly) from the opposite side of the room.


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## asarose247

@expl0sive

If not in plywood box, yes, fiber containment is important . .

i'm not sure about the batts and how much "rigidity' will make them stay put as you want to have them do all by themselves . .

a lightweight idea is a piece of plastic lattice from a 4 x 8 sheet (?), as from HD.

just afew small screws strateigically placed would be a quick anchoring idea. .

HTH


----------



## xpl0sive

asarose247 said:


> @expl0sive
> 
> If not in plywood box, yes, fiber containment is important . .
> 
> i'm not sure about the batts and how much "rigidity' will make them stay put as you want to have them do all by themselves . .
> 
> a lightweight idea is a piece of plastic lattice from a 4 x 8 sheet (?), as from HD.
> 
> just afew small screws strateigically placed would be a quick anchoring idea. .
> 
> HTH


Oh I figured if I made the plug slightly bigger than the window reveal, they should stay put once shoved into the cavity. I'm not against using ply, but I would need to make it slightly smaller then add something around the perimeter to create a seal within my window reveal.


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## artsci2

xpl0sive said:


> ...My theater room has a window that I'm going to cover with a blind, but I want to shove some foam in the window cavity to reduce the negative affects of having a window in a theater. Can anyone recommend a product that would be suitable? ..


Maybe polyfill, the material used for speaker stuffing, is your solution. The cheapest I have found is in bulk pillows. Lay the pillows in the window cavity and hold them in with narrow boards screwed to the window frame. If you have storm windows I would also shove pillows in the cavity between windows too.


----------



## fatallerror

OJ Bartley said:


> This seems pretty similar to another post I saw that recommended a healthy mix of absorption and diffusion, with more absorption up front and more diffusion to the rear, including cloud treatments.
> 
> I know that the ideal way to proceed is to measure the untreated room and determine exactly what is needed, but that isn't always possible so I will likely dip my toe in and start with a strategy similar to the above, and see where that gets me.


I'm also into the subject and found similar responses like this, front of the room is mainly absorption, back is diffusion. Like on this picture. So I guess that's the way to go to handle reflections.


----------



## xpl0sive

artsci2 said:


> Maybe polyfill, the material used for speaker stuffing, is your solution. The cheapest I have found is in bulk pillows. Lay the pillows in the window cavity and hold them in with narrow boards screwed to the window frame. If you have storm windows I would also shove pillows in the cavity between windows too.


I ended up buying some very dense foam and cutting it down to size. Works well, but it's quite rigid and I cut it a little too big, so it wants to bow out of the window frame. I might try cutting it a tad smaller so there isn't as much pressure on the top and bottom.


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## gigging

Hello,
I bought enough roxul safe and sound and 2x2x8’s to build (2) corner bass traps. I will be putting one in each of my front corners. I have a false wall with 24” of space in it. The false wall is covered with 1/4 plywood. Do I place the corner bass traps behind the screen wall or in front of the screen wall? My room is 28x20x8’s Thank you! 


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## Ladeback

gigging said:


> Hello,
> I bought enough roxul safe and sound and 2x2x8’s to build (2) corner bass traps. I will be putting one in each of my front corners. I have a false wall with 24” of space in it. The false wall is covered with 1/4 plywood. Do I place the corner bass traps behind the screen wall or in front of the screen wall? My room is 28x20x8’s Thank you!
> 
> 
> Sent from my iPhone using Tapatalk


I would place it behind the screen wall so you won't see it. Check this out. This may help.

http://www.acousticfrontiers.com/another-avs-forum-home-theater-of-the-month-for-acoustic-frontiers/


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## cheyne2525

I'll keep it short and sweet today guys, i just wanted to run my idea by some fellow AVS members to test out it's logic and veracity. 
I am about to build some custom cabinetry for the front of my non-dedicated home theater. Per it being my only option for placement in the home theater half of the room, this new cabinetry will be located on the front wall, between 8"-24" behind the front 3 L/C/R speakers. Among the research i have done on this, i read an article by Art Noxon at the ASC blog where he mentioned that having an entertainment center / cabinetry / etc. located on the front sound stage area is a bad idea in general as it distorts some of the sound imaging due to unwanted reflections bouncing off of the hard surfaces/bays and equip. located there.

My idea to help mediate this problem is to build some custom cabinetry that's made as acoustically transparent as possible. By this, i mean building a very minimal, but functional, cabinetry framework, which I would use in conjunction with some acoustically porous partitions - plastic square hole mesh covered by speaker grill cloth placed in thin frames, rather similar to a 12"x 18"square speaker grill cover - to separate each of the interior cabinetry bays. 

As for the shelving inside the cabinetry, i was going to build them using a very basic design - a frame with square hole grating/mesh attached to it as the main shelf surface (think a little smaller than chicken wire size mesh).

I've been trying to figure out if it the attempt to build such an unusual cabinetry design would be worthwhile, so any and all suggestions or alternatives are appreciated here.


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## gigging

Ladeback said:


> I would place it behind the screen wall so you won't see it. Check this out. This may help.
> 
> 
> 
> http://www.acousticfrontiers.com/another-avs-forum-home-theater-of-the-month-for-acoustic-frontiers/




Thank you! That’s what I was wanting to hear. Appreciate the link too!


Sent from my iPhone using Tapatalk


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## Ladeback

gigging said:


> Thank you! That’s what I was wanting to hear. Appreciate the link too!
> 
> 
> Sent from my iPhone using Tapatalk


I've been the Hodor Theater, very impressive.


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## Blue

sdurani said:


> With those Kef speakers, I wouldn't absorb (or diffuse) the near-wall first reflections. Instead, I would absorb the each speaker's first reflection on the far wall (contra-lateral reflections). This way, sounds intended for one side of the soundstage don't come at you (even subtly) from the opposite side of the room.


This is interesting. From my prior reading, I thought the first step is always to absorb the first reflection point. I have no expertise whatsoever, so perhaps I didn't fully understand the things I read in the past about room treatments. 

Does anyone know whether the DIYSG HTM-12s would fall in the category of (a) having good off-axis response, such that I should consider absorbing the far wall reflection point but not the near wall spot, or (b) having weaker off-axis response such that I should consider absorbing the near wall first reflection point? 

Also, is it one or the other, or is it advisable to absorb both the near and far wall first reflection points if your speakers don't have strong off-axis response?


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## fatallerror

Blue said:


> This is interesting. From my prior reading, I thought the first step is always to absorb the first reflection point. I have no expertise whatsoever, so perhaps I didn't fully understand the things I read in the past about room treatments.
> 
> Does anyone know whether the DIYSG HTM-12s would fall in the category of (a) having good off-axis response, such that I should consider absorbing the far wall reflection point but not the near wall spot, or (b) having weaker off-axis response such that I should consider absorbing the near wall first reflection point?
> 
> Also, is it one or the other, or is it advisable to absorb both the near and far wall first reflection points if your speakers don't have strong off-axis response?


Most basic treatments guides are for stereo sound, for home theatre treatment the opinions are vary. Some say that you don't need to treat first side wall reflections at all and just treat the corners and use diffusion behind you and near the surrounds to enhance soundstage. Lots of suggestions, depends on your room characteristics and speakers.


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## HopefulFred

Blue said:


> Does anyone know whether the DIYSG HTM-12s would fall in the category of (a) having good off-axis response, such that I should consider absorbing the far wall reflection point but not the near wall spot, or (b) having weaker off-axis response such that I should consider absorbing the near wall first reflection point?
> 
> Also, is it one or the other, or is it advisable to absorb both the near and far wall first reflection points if your speakers don't have strong off-axis response?


I don't want to speak for Sanjay, but a) generally all DIYSG speakers have good off-axis performance (that was the reason for the development of the SEOS waveguide in the first place) and b) it's not an either/or proposition, necessarily. I would generally not recommend you absorb same-side primary lateral reflection from an SEOS speaker, but I would strongly encourage you to toe them in strongly.

For folks with speakers that are ill-behaved off-axis, toe-in should be more moderate and same-side absortion should be considered. Opposite side treatment is less useful because off the diminished toe angle.


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## Blue

HopefulFred said:


> I don't want to speak for Sanjay, but a) generally all DIYSG speakers have good off-axis performance (that was the reason for the development of the SEOS waveguide in the first place) and b) it's not an either/or proposition, necessarily. I would generally not recommend you absorb same-side primary lateral reflection from an SEOS speaker, but I would strongly encourage you to toe them in strongly.
> 
> For folks with speakers that are ill-behaved off-axis, toe-in should be more moderate and same-side absortion should be considered. Opposite side treatment is less useful because off the diminished toe angle.


Thanks. I built my baffle wall with toe-in, so I'm in good shape there. Do you recommend absorption on the first reflection point of the side wall opposite each side speaker?


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## HopefulFred

Blue said:


> Do you recommend absorption on the first reflection point of the side wall opposite each side speaker?


I think it's a smart idea and worth pursuing. I'd suggest a trial before you spend a bunch of time and money (I'd suggest that for most treatment).


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## ncabw

I have some left over Forbo material from a project we did. The designer specs this product as a pin board but was suppose to have some sound dampening qualities. We installed it on the walls in a bunch of rooms. I have enough to do 3 full walls in my room. The only spec sheet I could find online so far is this one. I have no idea what the sound absorption coefficient means or if the number is any good. All I know is it’s expensive and have no other use for this material. LOL. 











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## UltimateUser

*All wall curtaining effect on sound*

I'm currently building a cinema and wish to create a 'black-hole' to minimise light reflections by using black fabric on all walls and even the ceiling. This is because I dislike reflections from painted surfaces, and it allow me to hide all the wiring and speakers neatly and cheaply. 

I think velvet will be too expensive, so anticipate using a cheap thin cotton fabric, with some sort of acoustically transparent material, such as spandex, over the surround wall speakers. For speakers, I'll have something similar to the HTM-12s for fronts, and Volt-8s for surrounds. 

1. Will the curtaining ruined the acoustics due to too much high frequency absorption? 

2. Can I mitigate absorption by painting the concrete floor black rather than carpeting? 

Cheers!


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## ereed

UltimateUser said:


> I'm currently building a cinema and wish to create a 'black-hole' to minimise light reflections by using black fabric on all walls and even the ceiling. This is because I dislike reflections from painted surfaces, and it allow me to hide all the wiring and speakers neatly and cheaply.
> 
> I think velvet will be too expensive, so anticipate using a cheap thin cotton fabric, with some sort of acoustically transparent material, such as spandex, over the surround wall speakers. For speakers, I'll have something similar to the HTM-12s for fronts, and Volt-8s for surrounds.
> 
> 1. Will the curtaining ruined the acoustics due to too much high frequency absorption?
> 
> 2. Can I mitigate absorption by painting the concrete floor black rather than carpeting?
> 
> Cheers!


While velvet will absorb some high frequency in the room you may want to add bass traps as well to balance the sound so it will not feel like highs are overly absorbed.


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## corradizo

UltimateUser said:


> I'm currently building a cinema and wish to create a 'black-hole' to minimise light reflections by using black fabric on all walls and even the ceiling. This is because I dislike reflections from painted surfaces, and it allow me to hide all the wiring and speakers neatly and cheaply.



How would you attach the fabric to the ceiling? I've been trying to figure this out myself.


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## UltimateUser

corradizo said:


> How would you attach the fabric to the ceiling? I've been trying to figure this out myself.



I dunno. Staple gun? Plasterboard screws painted black? It'll look classy.


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## UltimateUser

At the moment I have this: 



https://www.avsforum.com/forum/attachment.php?attachmentid=2443378&d=1534634045


It's light cotton fabric tied into a knot at each corner (like a knotted handkerchief), s-shaped hooks inserted into the knots and then those are hooked into eyes screwed into the plasterboard. In a diagonal I have black stretchy cord running between the hooks. It works great - completely black non reflective ceiling - and is very cheap. But sort of looks it too - it's a hippy vibe.


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## guptown

Forgive me if this question is completely off but I wanted to at least ask before I order my acoustical treatment supplies to finish my room.

My room is small. Less than 200 sf. I've built a stage per the frequently seen designs on this board to act as a bass trap. I've also built a (lightweight) soffit of 2x4s, metal track and will stuff with pink fluffy. The rest of the room is drywall. I plan on covering the walls (floor to ceiling) with DIY panels like those seen in Home Theater for Hobbits 2.0. Because the room is small I may not be able to utilize 2" OC 703 for all my panels. So here's my question...an often quoted number for total absorption in the room is to not exceed more than 25% of the SA of the room. What if I double that and cover 50% of the room with 1" OC 703. Will this give me a similar absorption result to going with 2" over 25% of the room? Or will I get same results with 1" but the room is "deader" bc of too much absorption? Are the absorption coefficients a function of the material on the surface and not the sum total of the absorption in the room? 

Hope this makes sense and I really appreciate any input.

Ray


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## OJ Bartley

I'm not an expert, but that sounds like you'll be overdamping the higher frequencies, and be lacking in the lower. With 1" of OC 703, it will only really be effective above a certain frequency (I'm not sure what that will be, but definitely on he higher end). You'll be sucking too much of that content out, and not having much impact at all below that frequency.


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## sdurani

guptown said:


> What if I double that and cover 50% of the room with 1" OC 703.


Will be like turning down the treble knob on your receiver. 1" OC703 absorbs well down to about 1,000 Hz, with the absorption dropping off below that. 2" OC703 is good down to the 300-500 Hz range and drops off below that. By absorbing high or mid-to-high frequencies, the panels will act like a form of tone control rather than broadband absorption; i.e., will change the tone of the sound (like an equalizer) rather than evenly absorb some of sound from your speakers. To absorb broadband (roughly down to where the speakers cross over to the sub) would require 6" OC703 on the wall or 4" OC703 spaced 4" from the wall. A few of those, strategically placed, will be more effective than covering 50% the room with 1" panels.


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## Harddrive2

*Bass Traps vs Angled Corners*

Hi,

I'm in the process of planning to finish my basement and have the opportunity to build a dedicated room. One half of the space is defined by foundation walls so the plan would be to build bass traps into those corners when the walls are finished. The opposite side of the room is part of the open space of the basement, so when I wall it off to make a dedicated room I have the opportunity to join the walls with a 45 degree angle instead of the traditional 90 degrees. Please see the attached simple drawing.

My thinking is that without a 90 degree corner there is no need for bass traps in that location. Why build a 90 degree corner only to then cut it off with a triangular bass trap?

Has anyone else done this or considered it? Pros and cons?

Thanks!
HDD


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## grendelrt

Has anyone used fabric track to make a 2" acoustic panel for the ceiling? Someone posted about it in the Black Theater thread, and it looks like it would make doing ceiling panels pretty easy. Was curious if anyone had used it , how it went, and where they sourced it.


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## sdurani

Harddrive2 said:


> My thinking is that without a 90 degree corner there is no need for bass traps in that location. Why build a 90 degree corner only to then cut it off with a triangular bass trap?


Lack of a 90-degree corner is not a bass trap. Bass traps are made of absorbent material. Walling off a 90-degree corner is not going to do the same thing.


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## Harddrive2

sdurani said:


> Lack of a 90-degree corner is not a bass trap. Bass traps are made of absorbent material. Walling off a 90-degree corner is not going to do the same thing.


Sorry, my bad on explaining myself poorly. The idea is not to wall off a 90 degree corner, but instead build the room so it does not have 90 degree corners at all, thus reducing and perhaps eliminating the need for bass traps that would be needed because of the 90 degree corners. Attached is a better drawing of the idea. Note the 45 degree wall element is not a false wall that covers over a 90 degree corner. There is no corner hiding behind the 45 degree wall. 

In a normal square or rectangular room the corners are subject to standing waves from both orthogonal directions, thus making traps in the corners very useful in smoothing out the room's standing waves. If the corners are replaced by 45's, new corner-to-corner standing waves will be introduced, but the lateral standing waves will be greatly reduced due to the lack of reinforcing corners. It seems to me this is worth consideration, and I'm curious if anyone has already looked into this concept and produced results or opinions.

Thanks,
HDD


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## HopefulFred

Harddrive2 said:


> If the corners are replaced by 45's, new corner-to-corner standing waves will be introduced, but the lateral standing waves will be greatly reduced due to the lack of reinforcing corners.


This statement hilights the misapprehension common in people new to small room accoustics. The corner has nothing to do with the reinforcement of standing waves. Removing the 90 degree corner may change the pattern of standing waves, but seldom for the better.

Standing waves will be present between any two opposing surfaces. It's easy to imagine that by effectively shortening those two surfaces, you might reduce the influence of the standing wave established between them, and to some extent that is probably true; however you've also increased the influence of the another set of standing waves formed between the new surfaces you introduced. I can't logically argue you out of thinking that there is some local optimum achieved with some magical size and shape room, except to say that computer models are quite effective at this and haven't found one.

The other misconception in your suggestion is that something relavent to bass is actually happening in the corner. Statements like "bass builds up in the corner" contribute to this misconception and almost everyone says that, so what's wrong with it? We almost always attempt to absorb and improve bass with porous or fibrous bass traps. These materials function by slowing the velocity of air molecules as they propagate sound waves. Their ability to do that is a function of their porosity (percent open space) and the shape of those open spaces. Open spaces within the material need to be irregular so that the pattern of molecular motion in the air is disrupted. Given that understanding, the next conceptual step is to fit that with standing waves.

Standing waves have areas of high velocity motion and areas of virtually no motion - the energy of the wave is, in a sense, traded back and forth between the kinetic energy of molecular motion and the energy of pressure as the wave reflects off surfaces back over itself. At reflecting surfaces, we have no velocity - high pressure instead.

Now we see that porous absorbers would be most effective absorbing a standing wave if they are positioned where the energy of the wave is expressed as motion. Where is that? It depends on the order of the standing wave - but it is never against the reflecting surface, always out in the room. (This is why thicker bass traps are more effective - they are simply farther from the walls, out in the room where the air is moving, not under pressure.)

So why put porous traps in corners? Two reasons, in no particular order. You won't be sitting there anyway; the high pressure of the reflecting sounds is bad sounding (this is what is really meant by "bass builds up in the corner"). When you are in the corner, you're in the high pressure region for the sets of standing waves established between both sets of walls, so you hear all the resonances as strongly as possible. And that's related to the second reason to put bass traps in corners: they can interact with all the standing waves. A trap in (near) a corner functions to mitigate the longitudinal and transverse waves simultaneously. So its effect is maximized in terms of overall usefulness, without taking up useful floor space.

(I'm sure this post needs editing and revision, but this is the best I can do from my cellphone at the moment.)


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## sdurani

^^^ Right said Fred. 

Changing room shape doesn't address the problem of standing waves, just makes them harder to predict. To minimize the largest standing waves, which occur in the subwoofer range, you would need really thick absorbers (feet, not inches). Much easier and more effective to minimize standing waves with subwoofer placement.


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## ereed

What above said! Bass bounces EVERYWHERE, not just corners. Yes corners the bass can "pool" there longer but its bouncing all over floor, ceiling, side walls, etc. So you need bass traps anyway.


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## asarose247

So very well stated . . .

The other misconception in your suggestion is that something relavent to bass is actually happening in the corner. Statements like "bass builds up in the corner" contribute to this misconception and almost everyone says that, so what's wrong with it? We almost always attempt to absorb and improve bass with porous or fibrous bass traps. These materials function by slowing the velocity of air molecules as they propogate sound waves. Their ability to do that is a function of their porosity (percent open space) and the shape of those open spaces. Open spaces within the material need to be irregular so that the pattern of molecular motion in the air is disrupted. Given that understanding, the next conceptual step is to fit that with standing waves.

Anybody using or tried activated charcoal panels?


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## ScottieBoysName

I'm thinking about picking up some acoustic panels from either GIK or ATS (any opinions there?) and starting to treat my room. I'm going to do the "mirror" test this afternoon, but I wanted to get a jump and see if any of you could spot some problem areas right away. I'm thinking I need to move the mains out into the room a bit more - and treat the side walls between the front and back of the room first. So - 9 panels. 

One on either side of the L/R surround. 4 panels
One on the side of each L/R main. 2 panels
One on either side of the subs at the rear. 2 panels
One on the back wall/ceiling on either side of the rear atmos speakers? 1 panel

Is it more important to treat the sides of the theater versus the front and the back? 

I was thinking of going with 4 inch thick panels versus 2. 

Pics are attached. 

I also need to do something about the cavity behind the screen.


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## ereed

ScottieBoysName said:


> I'm thinking about picking up some acoustic panels from either GIK or ATS (any opinions there?) and starting to treat my room. I'm going to do the "mirror" test this afternoon, but I wanted to get a jump and see if any of you could spot some problem areas right away. I'm thinking I need to move the mains out into the room a bit more - and treat the side walls between the front and back of the room first. So - 9 panels.
> 
> One on either side of the L/R surround. 4 panels
> One on the side of each L/R main. 2 panels
> One on either side of the subs at the rear. 2 panels
> One on the back wall/ceiling on either side of the rear atmos speakers? 1 panel
> 
> Is it more important to treat the sides of the theater versus the front and the back?
> 
> I was thinking of going with 4 inch thick panels versus 2.
> 
> Pics are attached.
> 
> I also need to do something about the cavity behind the screen.


I'd start with bass traps in the corners first and then go from there to first reflection points on side wall. Then its up to you if you feel like you want to go further after that.


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## ScottieBoysName

ereed said:


> I'd start with bass traps in the corners first and then go from there to first reflection points on side wall. Then its up to you if you feel like you want to go further after that.


Should I make them or buy them? The seem quite a bit more expensive pre-made than panels.


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## ereed

ScottieBoysName said:


> Should I make them or buy them? The seem quite a bit more expensive pre-made than panels.


If you know how to DIY and know what you are doing then DIY will save you money. But buying from someone that has put in the research and have their panels tested such as GIK guarantees that you have a high quality working product and just ready to order. Its up to you. Personally I have GIK and their products work and they have free advice where you talk to them and they give you recommendations where to start based on your budget and goals.


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## ScottieBoysName

ereed said:


> If you know how to DIY and know what you are doing then DIY will save you money. But buying from someone that has put in the research and have their panels tested such as GIK guarantees that you have a high quality working product and just ready to order. Its up to you. Personally I have GIK and their products work and they have free advice where you talk to them and they give you recommendations where to start based on your budget and goals.


I do value expertise. Bass traps can kinda be....anything though can't they? Something that's not dense...and then a lot of it. Right? I've seen people basically stack bags of pink fluffy or rockwool and use that.


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## ereed

ScottieBoysName said:


> I do value expertise. Bass traps can kinda be....anything though can't they? Something that's not dense...and then a lot of it. Right? I've seen people basically stack bags of pink fluffy or rockwool and use that.


I've never DIY acoustic panels so I wouldn't know the best materials for them. I know some have used pink fluffy, roxul safe and sound, Knauf insulation, etc. No clue which material is superior....this is why I bought mine instead.


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## Tom Riddle

Happy Thanksgiving, all! 

I'm putting together my dedicated HT, which was just built, and the acoustic panels are a daunting task. I already had 2) 24x4x48" GIK acoustic panels and purchased 6) 24x2x48, 4) 24x2x24" acoustic panels, and 4) 24x4x48" bass traps from Acoustimac. I have a build thread in my signature labeled "Routh Family Theater", if anyone would be able to go look at the pictures and offer advice. The room is 12x17', but has a slight L shape towards the back where it narrows to 10'. The room also has a pony wall to 4' walls on the left side. So, not the ideal shape for an HT room, but hey, I made the best use out of my attic on the 2nd floor that connected directly to my game room!

There are plenty of pictures there and any advice would be much appreciated!


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## sdurani

ScottieBoysName said:


> Is it more important to treat the sides of the theater versus the front and the back?


Other way 'round. Reflections off the side walls are outside the front L/R speakers, so they aid in spaciousness and broadening of the front soundstage. Whether you end up liking that effect is up to your personal preference. By comparison, reflections off the front wall (especially between the L/R speakers) can muddy articulation and clarity because they're coming from the same direction as the front soundstage. Reflections off the back wall have a similar effect.


> I was thinking of going with 4 inch thick panels versus 2.


Good idea. If you can space them a few inches off the wall, that will make their absorption even more broadband. The problem with absorbers that are too thin is that they mostly absorb higher frequencies and end up acting like a tone control (like turning the treble knob down).


> I also need to do something about the cavity behind the screen.


Hang or stack pink fluffy insulation for some bass trapping.


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## ScottieBoysName

sdurani said:


> Other way 'round. Reflections off the side walls are outside the front L/R speakers, so they aid in spaciousness and broadening of the front soundstage. Whether you end up liking that effect is up to your personal preference. By comparison, reflections off the front wall (especially between the L/R speakers) can muddy articulation and clarity because they're coming from the same direction as the front soundstage. Reflections off the back wall have a similar effect. Good idea. If you can space them a few inches off the wall, that will make their absorption even more broadband. The problem with absorbers that are too thin is that they mostly absorb higher frequencies and end up acting like a tone control (like turning the treble knob down). Hang or stack pink fluffy insulation for some bass trapping.



Ok that helps out a ton. Hmmm - I really like "spaciousness" and a "wide" type of sound. So possibly I'll not want to treat the sidewalls. As far as the back wall I think I can manage something there. 

On the front wall there's very little space between the sides of the screen - like 19 inches. I'm also going to put velvet there - so I'd rather not put a panel over that - defeats the purpose. Unless it was a panel covered in velvet! I think velvet covered acoustic panels don't work so well - correct?

So - the sidewalls NEXT to the L/R mains - that area just in front of the first column - would you consider that part of the sides since it's basically behind the mains or would it count as part of the front since the speakers are really in front of it? I don't mind treating that - as it will be covered in velvet as well but if I treat that will it reduce the "spaciousness" and "broadening" of the front stage?

In the front cavity - can I leave the pink fluffy still in the bags? I'd rather not have it open to the air in that room. What does leaving it in the bags do? I've heard the plastic actually helps reduce/trap bass.


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## ereed

ScottieBoysName said:


> Ok that helps out a ton. Hmmm - I really like "spaciousness" and a "wide" type of sound. So possibly I'll not want to treat the sidewalls. As far as the back wall I think I can manage something there.
> 
> On the front wall there's very little space between the sides of the screen - like 19 inches. I'm also going to put velvet there - so I'd rather not put a panel over that - defeats the purpose. Unless it was a panel covered in velvet! I think velvet covered acoustic panels don't work so well - correct?
> 
> So - the sidewalls NEXT to the L/R mains - that area just in front of the first column - would you consider that part of the sides since it's basically behind the mains or would it count as part of the front since the speakers are really in front of it? I don't mind treating that - as it will be covered in velvet as well but if I treat that will it reduce the "spaciousness" and "broadening" of the front stage?
> 
> In the front cavity - can I leave the pink fluffy still in the bags? I'd rather not have it open to the air in that room. What does leaving it in the bags do? I've heard the plastic actually helps reduce/trap bass.


If you want to treat side wall and still have spaciousness then you can use diffusion panels instead of broadband absorption panels. Something like Alpha panels from GIK.


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## ScottieBoysName

ereed said:


> If you want to treat side wall and still have spaciousness then you can use diffusion panels instead of broadband absorption panels. Something like Alpha panels from GIK.




I’ll check those out. I’m not sure how I’m going to be able to treat the front wall...but I’m working on it. 

The back wall should be fairly simple.


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## Tom Riddle

Tom Riddle said:


> Happy Thanksgiving, all!
> 
> I'm putting together my dedicated HT, which was just built, and the acoustic panels are a daunting task. I already had 2) 24x4x48" GIK acoustic panels and purchased 6) 24x2x48, 4) 24x2x24" acoustic panels, and 4) 24x4x48" bass traps from Acoustimac. I have a build thread in my signature labeled "Routh Family Theater", if anyone would be able to go look at the pictures and offer advice. The room is 12x17', but has a slight L shape towards the back where it narrows to 10'. The room also has a pony wall to 4' walls on the left side. So, not the ideal shape for an HT room, but hey, I made the best use out of my attic on the 2nd floor that connected directly to my game room!
> 
> There are plenty of pictures there and any advice would be much appreciated!


I hate to quote myself, but I wanted to add pictures to make it easier. Thanks for the help!


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## sdurani

ScottieBoysName said:


> So possibly I'll not want to treat the sidewalls.


Only place you might want to try absorption on the side walls is the contra-lateral first reflections (where the left speaker reflects off the right side wall and vice versa). That will prevent sounds on one side of the soundstage from coming at you (however subtly) from the opposite side of the room. Also consider toeing in your front L/R speakers so that they're aimed at the listener farthest away.


> As far as the back wall I think I can manage something there.


A 2' x 4' absorber on the back door should be fine.


> So - the sidewalls NEXT to the L/R mains - that area just in front of the first column - would you consider that part of the sides since it's basically behind the mains or would it count as part of the front since the speakers are really in front of it? I don't mind treating that - as it will be covered in velvet as well but if I treat that will it reduce the "spaciousness" and "broadening" of the front stage?


Stand up some absorption panels temporarily at those locations and see if the front soundstage sounds better or worse. Treating your room effectively means listening & deciding whether you like the results or not.


> In the front cavity - can I leave the pink fluffy still in the bags? What does leaving it in the bags do?


Bags will reflect the higher frequencies; but so will the screen in front of the absorption. When you buy the pink fluffy, save the receipt. IF you don't hear an improvement, return the insulation.


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## ScottieBoysName

sdurani said:


> Only place you might want to try absorption on the side walls is the contra-lateral first reflections (where the left speaker reflects off the right side wall and vice versa). That will prevent sounds on one side of the soundstage from coming at you (however subtly) from the opposite side of the room. Also consider toeing in your front L/R speakers so that they're aimed at the listener farthest away. A 2' x 4' absorber on the back door should be fine. Stand up some absorption panels temporarily at those locations and see if the front soundstage sounds better or worse. Treating your room effectively means listening & deciding whether you like the results or not. Bags will reflect the higher frequencies; but so will the screen in front of the absorption. When you buy the pink fluffy, save the receipt. IF you don't hear an improvement, return the insulation.




Got it. I’ve toed them in so far as the L faces the center L seat, and R faces the center R seat. So - more?

That makes sense on the contra lateral part. How do I see where that reflection is? Mirror test?

From what I’m getting this is a lot to try and see, eh?

Is the cavity possibly hurting sound in any way? Bass wise?


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## sdurani

ScottieBoysName said:


> I’ve toed them in so far as the L faces the center L seat, and R faces the center R seat. So - more?


Try playing a mono signal from your L/R speakers and see if you get a phantom centre image from the end seats. Then try aiming the L/R speakers to the listener at the opposite end of the row and try the mono test again from the end seats. Did the phantom imaging improve?


> How do I see where that reflection is? Mirror test?


Yup, the ol' mirror test.


> From what I’m getting this is a lot to try and see, eh?


Sure. It's not like your room is going anywhere. So keep experimenting. You'll hear for yourself which treatments make things better and which ones make things worse. That's more helpful that taking the word of some stranger on the internet.


> Is the cavity possibly hurting sound in any way? Bass wise?


Space behind the screen is an opportunity for bass trapping. Won't know whether it makes an improvement (or how much improvement) until you try it. Like I said, save the receipt. 

Also, any time you make changes (placing absorption panels, toeing in speakers, adding pink fluffy, etc), remember to re-run your receiver's auto calibration.


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## ScottieBoysName

sdurani said:


> Try playing a mono signal from your L/R speakers and see if you get a phantom centre image from the end seats. Then try aiming the L/R speakers to the listener at the opposite end of the row and try the mono test again from the end seats. Did the phantom imaging improve? Yup, the ol' mirror test. Sure. It's not like your room is going anywhere. So keep experimenting. You'll hear for yourself which treatments make things better and which ones make things worse. That's more helpful that taking the word of some stranger on the internet. Space behind the screen is an opportunity for bass trapping. Won't know whether it makes an improvement (or how much improvement) until you try it. Like I said, save the receipt.
> 
> Also, any time you make changes (placing absorption panels, toeing in speakers, adding pink fluffy, etc), remember to re-run your receiver's auto calibration.


Gotcha - alrighty - so...what's the easiest way to shoot a mono signal? 

Yuppers - I'll make sure and re-run Audyssey no matter what after any changes.


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## sdurani

ScottieBoysName said:


> Gotcha - alrighty - so...what's the easiest way to shoot a mono signal?


Old movie, test disc, REW, etc.


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## ScottieBoysName

sdurani said:


> Old movie, test disc, REW, etc.




Ahh sweet! I can use REW.


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## Player3

ScottieBoysName said:


> I’ll check those out. I’m not sure how I’m going to be able to treat the front wall...but I’m working on it.
> 
> The back wall should be fairly simple.


I've found that eliminating first reflections don't make the sound stage feel smaller, but larger! Btw, I have both ATS(4 inch thick and triangle bass traps) and GIK panels(244 and soffit bass traps), both are very effective and are nice products imo. GIK make open back panels though, which I like, as they don't just absorb from the front but also the sound as it hits the wall and travels back through them. For your first reflections, I would recommend full-range 244 panels. Both the ATS bass traps and the soffits are very effective, couldn't tell you which is better honestly. Also, the ceiling is crucial.. Ethan Winer(my favorite acoustic guru) recommends covering as much of the ceiling as you can actually, making the room sound "taller". Some will disagree, but I've found good results so far myself.


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## ScottieBoysName

Player3 said:


> I've found that eliminating first reflections don't make the sound stage feel smaller, but larger! Btw, I have both ATS(4 inch thick and triangle bass traps) and GIK panels(244 and soffit bass traps), both are very effective and are nice products imo. GIK make open back panels though, which I like, as they don't just absorb from the front but also the sound as it hits the wall and travels back through them. For your first reflections, I would recommend full-range 244 panels. Both the ATS bass traps and the soffits are very effective, couldn't tell you which is better honestly. Also, the ceiling is crucial.. Ethan Winer(my favorite acoustic guru) recommends covering as much of the ceiling as you can actually, making the room sound "taller". Some will disagree, but I've found good results so far myself.


Thanks!! Why do you suggest the 244s over the 242s for first reflections?


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## Player3

ScottieBoysName said:


> Thanks!! Why do you suggest the 244s over the 242s for first reflections?


Well the 242s are only 3.625 inches thick, while the 244 is 5.375 inches thick. It'll have *significantly* more absorption from 80-250hz, and to me that's a no-brainer as they're only $10 more per panel. 

EDIT: you can view the graphs measuring the 242/244 on their website. Looks like the measurements were done by two different places and one is in sabins and the other as absorption coefficient, but regardless you can see the effectiveness of the 244 down to 80hz at 13.88 sabins, where as the 242 has a mere .12 absorption coefficient at 80hz. (You can convert sabins to an equivalent absorption coefficient by simply dividing the sabins by the square feet of front surface area.)


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## ScottieBoysName

Player3 said:


> Well the 242s are only 3.625 inches thick, while the 244 is 5.375 inches thick. It'll have *significantly* more absorption from 80-250hz, and to me that's a no-brainer as they're only $10 more per panel.
> 
> EDIT: you can view the graphs measuring the 242/244 on their website. Looks like the measurements were done by two different places and one is in sabins and the other as absorption coefficient, but regardless you can see the effectiveness of the 244 down to 80hz at 13.88 sabins, where as the 242 has a mere .12 absorption coefficient at 80hz. (You can convert sabins to an equivalent absorption coefficient by simply dividing the sabins by the square feet of front surface area.)


Is that good, to technically have what one would consider bass traps at first reflection points? I honestly am curious. All this is new to me.


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## Player3

ScottieBoysName said:


> Is that good, to technically have what one would consider bass traps at first reflection points? I honestly am curious. All this is new to me.


No worries, that's a fair question! I had the same thought back in the day when I was learning some of this stuff, but although they are in name called "bass traps"(I guess in the sense that they do absorb some bass frequencies) the full-range 244 panels are just that--full range. As you can see from the tests, they absorb very well at 10khz. The 244s with the "flexrange technology" though are bass traps only, those you would *not* want to use for first reflections, as they would simply reflect the higher frequencies.

But anyhow, don't worry about having too much absorption for the low frequencies, you want as much of that as possible. 

This is my philosophy, as many bass-traps as possible, full-absorption of the first reflections, and scattered absorption/diffusion across the rest of the room. 

These are two videos I found very helpful when I was learning. I've put many things I learned into practice, and can't tell you enough how much better it's made my listening experience. They're long videos, but WORTH IT!


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## ScottieBoysName

Player3 said:


> No worries, that's a fair question! I had the same thought back in the day when I was learning some of this stuff, but although they are in name called "bass traps"(I guess in the sense that they do absorb some bass frequencies) the full-range 244 panels are just that--full range. As you can see from the tests, they absorb very well at 10khz. The 244s with the "flexrange technology" though are bass traps only, those you would *not* want to use for first reflections, as they would simply reflect the higher frequencies.
> 
> But anyhow, don't worry about having too much absorption for the low frequencies, you want as much of that as possible.
> 
> This is my philosophy, as many bass-traps as possible, full-absorption of the first reflections, and scattered absorption/diffusion across the rest of the room.
> 
> These are two videos I found very helpful when I was learning. I've put many things I learned into practice, and can't tell you enough how much better it's made my listening experience. They're long videos, but WORTH IT!
> 
> https://www.youtube.com/watch?v=XKZfZqRiZXY&t=89s
> 
> https://www.youtube.com/watch?v=raAyF5ksbkk



AWESOME. So..it's not possible then to OVER absorb bass? OR have too many bass traps? What I want to avoid though - is having a dead room. I'm all about openness/ambiance/wide/spaciousness/etc. The speaker locations in my room aren't ideal - so having that illusion of them being in places they aren't is a good thing in some instances in my mind. 

So - if I'm hearing you right - you can't have too many bass traps, but you can over absorb the higher frequencies?


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## Player3

ScottieBoysName said:


> AWESOME. So..it's not possible then to OVER absorb bass? OR have too many bass traps? What I want to avoid though - is having a dead room. I'm all about openness/ambiance/wide/spaciousness/etc. The speaker locations in my room aren't ideal - so having that illusion of them being in places they aren't is a good thing in some instances in my mind.
> 
> So - if I'm hearing you right - you can't have too many bass traps, but you can over absorb the higher frequencies?


Correct. And again, the soundstage at least in my experience became wider/more open/spacious etc. when I implemented my first reflection treatments, not the other way around. The way you deaden a room is by adding too many full-range absorption panels _throughout_ the room.. The goal is *total* absorption of the first reflection points, but in front of and behind the reflection points, I would have a *balanced* approach to absorption and diffusion. So on a back wall or sidewall behind the first reflections you could do like 50/50, some diffusion, some absorption.


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## ScottieBoysName

Player3 said:


> Correct. And again, the soundstage at least in my experience became wider/more open/spacious etc. when I implemented my first reflection treatments, not the other way around. The way you deaden a room is by adding too many full-range absorption panels _throughout_ the room.. The goal is *total* absorption of the first reflection points, but in front of and behind the reflection points, I would have a *balanced* approach to absorption and diffusion. So on a back wall or sidewall behind the first reflections you could do like 50/50, some diffusion, some absorption.


Got it. I need to figure out where the first and second points are in my room.


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## Player3

ScottieBoysName said:


> Got it. I need to figure out where the first and second points are in my room.


Oh don't forget about the ceiling! The ceiling is just as much a sound reflector as the walls. Also, not to discredit his opinion but not sure I would agree with sdurani about the side reflections. Based on what I've experienced the sidewalls/ceiling are the most consequential--I would *for sure* treat those. But as he suggested, try moving the panels around before you mount them and see what you think and what you like the sound of! After all, it's your room.


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## ScottieBoysName

Player3 said:


> Oh don't forget about the ceiling! The ceiling is just as much a sound reflector as the walls. Also, not to discredit his opinion but not sure I would agree with sdurani about the side reflections. Based on what I've experienced the sidewalls/ceiling are the most consequential--I would *for sure* treat those. But as he suggested, try moving the panels around before you mount them and see what you think and what you like the sound of! After all, it's your room.


I don't suppose anyone can let me know how to do the mirror trick with one person and a small mirror. LOL. 

I'll certainly lean the panels up against the walls and see what sounds best where. 

If you look at my pictures, my ceiling is reverse vaulted - so that sound directly reflects back at the MLP. Not sure if that's good or bad.


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## ereed

ScottieBoysName said:


> AWESOME. So..it's not possible then to OVER absorb bass? OR have too many bass traps? What I want to avoid though - is having a dead room. I'm all about openness/ambiance/wide/spaciousness/etc. The speaker locations in my room aren't ideal - so having that illusion of them being in places they aren't is a good thing in some instances in my mind.
> 
> So - if I'm hearing you right - you can't have too many bass traps, but you can over absorb the higher frequencies?


You can't have too many bass traps. You want to have as much as you can and as thick as you can. Low freq wave lengths are long so you want to keep them from bouncing around. Only time you would have dead room is if you absorb all high frequencies.


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## ereed

ScottieBoysName said:


> Got it. I need to figure out where the first and second points are in my room.


If you don't have someone to help you then you can do this alone by getting a cheap floor mirror from Walmart. Have it standing up against the wall and sit down and keep moving the mirror til you see the speaker from your MLP. If you're on the right wall and you see the right speaker that is your first reflection point. To get 2nd reflection point on same right wall, slide mirror til you see left speaker. Make sense? And put your panels there. Depending on your room you want to either absorb or diffuse. I'm using combo of absorption and diffusion on my first and 2nd reflection points using the GIK Alpha 4A panels. 

Rule of thumb....if you feel like your room is bright use absorption...if you like how it sounds and not bright sounding then use diffusion to cut energy without making it dead.


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## ScottieBoysName

ereed said:


> You can't have too many bass traps. You want to have as much as you can and as thick as you can. Low freq wave lengths are long so you want to keep them from bouncing around. Only time you would have dead room is if you absorb all high frequencies.



Good to know I can't over do it on those. I tend to lean towards "too much" rather than "too little".


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## ScottieBoysName

ereed said:


> If you don't have someone to help you then you can do this alone by getting a cheap floor mirror from Walmart. Have it standing up against the wall and sit down and keep moving the mirror til you see the speaker from your MLP. If you're on the right wall and you see the right speaker that is your first reflection point. To get 2nd reflection point on same right wall, slide mirror til you see left speaker. Make sense? And put your panels there. Depending on your room you want to either absorb or diffuse. I'm using combo of absorption and diffusion on my first and 2nd reflection points using the GIK Alpha 4A panels.
> 
> Rule of thumb....if you feel like your room is bright use absorption...if you like how it sounds and not bright sounding then use diffusion to cut energy without making it dead.


This is perfect! Thank you so much!


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## PretzelFisch

ScottieBoysName said:


> This is perfect! Thank you so much!


you can also calculate where it should go http://realtraps.com/art_room-setup3.gif


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## ScottieBoysName

PretzelFisch said:


> you can also calculate where it should go http://realtraps.com/art_room-setup3.gif


Little math there eh?


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## ScottieBoysName

Filled up the cavity this weekend. I’m going to cover it with something later. Prolly next week. 

There’s 19inches of pink fluffy there. Two rolls of R30


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## sassuki

Forget all this crazy insulation and diffusion panels... I just found the only thing I need for perfect acoustics in my room. 
http://shunmook.com/hifiproduct_4.html
Smh


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## corradizo

ScottieBoysName said:


> Little math there eh?




Can also draw it out if handy with SketchUp, no?


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## ScottieBoysName

corradizo said:


> Can also draw it out if handy with SketchUp, no?


It's cool. I used a mirror and stuck with that. No worries.


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## ncabw

I want to make 4 “superchunk” bass traps with roxul safe n sound. I’m in a bit of a rush and don’t have the time to get my fabric for the front face. I plan in doing that at another date. I’ve seen pictures of people using a peg board for the front face. Is that good for a temporary fix or maybe even permanent? I don’t want the insulation exposed because my kids will definitely pick at it. 










I plan I’m just painting it black or grey for now. 

Thanks 


Sent from my iPhone using Tapatalk


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## kgveteran

I have about 96 cubic feet of corner super chunk traps, diffusers to eliminate flutter echo, and absorbers for FRP. I would say at the LP its all about RFZ.
I watched FallOut the other nite, in 7.1.4 Atmos, it was amazing, never went much beyond -13dbMV. This is my fourth room since i started hometheatering :0) around 1988ish
I cant believe how this one sounds, the room is 13x19x vaulted ceiling.

ThankYou Acoustic Treatments, ur the unsung hero of all rooms (and they are all bad) !


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## midblue

*Height mode null around 70hz*

Hi all, hope this is the right place to ask. I have a pretty big null at 72.5hz in my room. Here is my subwoofer response graph pre-Audyssey:










I am running two Rythmik FV18, at 1/4 and 3/4 of the front wall. I am very happy with the performance overall, and Audyssey does help clear this up a bit, but this dip hurts the crossover range and it's slightly audible in music, so I'd like to address it if possible. 

I'm pretty sure this is caused by a height mode. The mode calculator spreadsheet tells me there should indeed be a null at 73hz because my room height is 7'9". I verified this with the REW SPL meter and tone generator at 72hz - there is a 20-30db difference if I raise the microphone to the ceiling or the floor, as compared to the middle of the room, around 3-4ft (listening height).

I have a good deal of bass trapping on the side walls and Tri-Traps in the front corners. I could add some 2'x4'x7.5" bass traps to the ceiling behind the listening position, with cloud mounts. I could also add a few more 1'x4'x7.5" bass traps to the ceiling between the subs and the MLP. I might be able to squeeze in a few more 2'x2's in other locations on the ceiling. I could also toss a soffit trap on the floor along one of the side walls, or 1-2 behind the couch.

The question: Would more trapping as described on the ceiling, or soffit trapping, help with this null? The bass traps I'm using (GIK) are rated down to 70hz, the soffits down to 40hz. If trapping would help, how much would I need and where is the best spot?

I can't move the subs, but if I added another one VNF behind the couch, would that help? It would also need to be floor-level like the FV18s, I couldn't raise it up to the null.


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## ereed

midblue said:


> Hi all, hope this is the right place to ask. I have a pretty big null at 72.5hz in my room. Here is my subwoofer response graph pre-Audyssey:
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> I am running two Rythmik FV18, at 1/4 and 3/4 of the front wall. I am very happy with the performance overall, and Audyssey does help clear this up a bit, but this dip hurts the crossover range and it's slightly audible in music, so I'd like to address it if possible.
> 
> I'm pretty sure this is caused by a height mode. The mode calculator spreadsheet tells me there should indeed be a null at 73hz because my room height is 7'9". I verified this with the REW SPL meter and tone generator at 72hz - there is a 20-30db difference if I raise the microphone to the ceiling or the floor, as compared to the middle of the room, around 3-4ft (listening height).
> 
> I have a good deal of bass trapping on the side walls and Tri-Traps in the front corners. I could add some 2'x4'x7.5" bass traps to the ceiling behind the listening position, with cloud mounts. I could also add a few more 1'x4'x7.5" bass traps to the ceiling between the subs and the MLP. I might be able to squeeze in a few more 2'x2's in other locations on the ceiling. I could also toss a soffit trap on the floor along one of the side walls, or 1-2 behind the couch.
> 
> The question: Would more trapping as described on the ceiling, or soffit trapping, help with this null? The bass traps I'm using (GIK) are rated down to 70hz, the soffits down to 40hz. If trapping would help, how much would I need and where is the best spot?
> 
> I can't move the subs, but if I added another one VNF behind the couch, would that help? It would also need to be floor-level like the FV18s, I couldn't raise it up to the null.


Adding a 3rd sub will help! Just curious...have you played with subwoofer distance setting in your AVR. Change the distance 1 foot at a time and remeasure in REW and see if the null goes away. I'm assuming your xover point is at 80hz?


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## midblue

ereed said:


> Adding a 3rd sub will help! Just curious...have you played with subwoofer distance setting in your AVR. Change the distance 1 foot at a time and remeasure in REW and see if the null goes away. I'm assuming your xover point is at 80hz?


That graph is _just_ the LFE channel, so no crossover in play. The dip is entirely caused by the room. 

Actually, when I measure the response of the center / mains blended with the subs (80hz crossover), it's not too bad through that range since the other speakers help out. Still a bit of a dip. However, any effects coming through the LFE channel alone are going to be subject to this null with nothing to help.

The third sub behind the couch would be a tough sell with the wife (that's where the dog sits and I don't want to break her ears). Also, I'd be worried about localization.

I still have my old HSUs though, I was going to sell them but I could try hooking one up and setting an aggressive cutoff at 90hz or so with miniDSP to help with localization. Worth a shot just to see what happens to the results.

Still interested in opinions on the potential effects of trapping on this null though!


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## ereed

midblue said:


> That graph is _just_ the LFE channel, so no crossover in play. The dip is entirely caused by the room.
> 
> Actually, when I measure the response of the center / mains blended with the subs (80hz crossover), it's not too bad through that range since the other speakers help out. Still a bit of a dip. However, any effects coming through the LFE channel alone are going to be subject to this null with nothing to help.
> 
> The third sub behind the couch would be a tough sell with the wife (that's where the dog sits and I don't want to break her ears). Also, I'd be worried about localization.
> 
> I still have my old HSUs though, I was going to sell them but I could try hooking one up and setting an aggressive cutoff at 90hz or so with miniDSP to help with localization. Worth a shot just to see what happens to the results.
> 
> Still interested in opinions on the potential effects of trapping on this null though!


That is good response just for subs. But if you want a flat graph you need to measure subs with center or mains. Center if mostly movies, mains if mostly music. 

3rd sub will help with that null....but you could always get lower profile chairs to get out of height null or put seat risers under your chair to get away from midpoint of height. As for the dog....the dog will move out of the way and find another place to sit if you add another sub. Nearfield really gives you that punch and tactile response farfield can't and I think you will like it. I have funk audio 18 inch right behind my seating and its not localizable and I'm using 100hz xover with addition to 2 svs pb13s (sealed mode) in front right and rear right corners to smooth things out. Adding thick treatment in ceiling could help as well.


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## sdurani

midblue said:


> I can't move the subs, but if I added another one VNF behind the couch, would that help?


Not for a height mode, since the sub would still be at one of the boundaries (floor, ceiling) responsible for the height mode. The easiest way to minimize that mode is to move the source of bass to the null of that mode at the midpoint of room height. Rather than raise your subs 4 feet off the floor, try setting the crossover below 70Hz (e.g., try a 60Hz crossover). Also, can you measure your centre speaker full range and post the measurement?


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## mtbdudex

ncabw said:


> I want to make 4 “superchunk” bass traps with roxul safe n sound. I’m in a bit of a rush and don’t have the time to get my fabric for the front face. I plan in doing that at another date. I’ve seen pictures of people using a peg board for the front face. Is that good for a temporary fix or maybe even permanent? I don’t want the insulation exposed because my kids will definitely pick at it.
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> I plan I’m just painting it black or grey for now.
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> Thanks
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> Sent from my iPhone using Tapatalk




That would work temporarily, what did you end up doing?
I used Kraft paper as a membrane for all my corner broadband bass traps .





























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## ncabw

mtbdudex said:


> That would work temporarily, what did you end up doing?
> I used Kraft paper as a membrane for all my corner broadband bass traps .
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I still have not made anything. Been real busy at work. I might do something like you posted. 


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## midblue

sdurani said:


> Not for a height mode, since the sub would still be at one of the boundaries (floor, ceiling) responsible for the height mode. The easiest way to minimize that mode is to move the source of bass to the null of that mode at the midpoint of room height. Rather than raise your subs 4 feet off the floor, try setting the crossover below 70Hz (e.g., try a 60Hz crossover). Also, can you measure your centre speaker full range and post the measurement?


I'll try some things over the weekend, including modifying the crossover. Here is my center channel response after Audyssey. Not too bad overall.










I also walked around with the REW SPL meter testing both 72hz tone and 10-100hz white noise and found some areas that have pretty high SPL. Couple areas along the ceiling and the ceiling/wall boundary. Probably good areas for trapping, although I'd have to buy more traps to test...


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## HopefulFred

midblue said:


> I'll try some things over the weekend, including modifying the crossover.
> I also walked around with the REW SPL meter testing both 72hz tone and 10-100hz white noise and found some areas that have pretty high SPL. Couple areas along the ceiling and the ceiling/wall boundary. Probably good areas for trapping, although I'd have to buy more traps to test...


High SP(ressure)L means low velocity - less performance from your porous absorbers. That's not to say that this won't ultimately be your most effective option - it might.

Have you tried phase? Perhaps adjusting the phase of one sub will result in a reasonable compromise. Certainly adjusting phase is going to have effects at other frequencies, but it might be worthwhile (as well as free and easy).


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## sdurani

midblue said:


> Here is my center channel response after Audyssey.


Your centre speaker goes down to 10Hz? The height mode dip is shallower because the source of bass (centre speaker) is closer to the midpoint of room height. The closer the source of bass gets to the null, the less the mode is excited. If you could temporarily place your centre speaker (at least its woofer) at the midpoint of room height, the dip might disappear.


> I also walked around with the REW SPL meter testing both 72hz tone and 10-100hz white noise and found some areas that have pretty high SPL. Couple areas along the ceiling and the ceiling/wall boundary.


Modes are always peaking at room boundaries, so SPL is highest there. This particular (72Hz) height mode peaks at the floor and ceiling, gradually working its way to a null at the midpoint of room height.


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## midblue

HopefulFred said:


> High SP(ressure)L means low velocity - less performance from your porous absorbers. That's not to say that this won't ultimately be your most effective option - it might.
> 
> Have you tried phase? Perhaps adjusting the phase of one sub will result in a reasonable compromise. Certainly adjusting phase is going to have effects at other frequencies, but it might be worthwhile (as well as free and easy).


Oh, interesting, I thought I had read that the areas of highest SPL indicated bass buildup where traps would be effective, but that makes sense about velocity. I wouldn't put the traps right up against the ceiling though, I would mount them with a 4-5" air gap to try to get the best performance.

I think my subs phase control is defeated when using the LFE input rather than line in. I can see what I could do through minidsp though. I tried a simple phase inversion on one just for kicks, but of course that killed everything across the board since they're equidistant.



sdurani said:


> Your centre speaker goes down to 10Hz? The height mode dip is shallower because the source of bass (centre speaker) is closer to the midpoint of room height.


Ah sorry, that was the center + subs, I read too quickly. The center is a bit higher than the subs, the center of the woofer cones is maybe 9" higher. That could indeed make a difference and would be interesting to see, I'll measure the center just by itself and get back to you.


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## ncabw

Can I build a bass trap right beside my rear speakers. I have 16” from back wall to where the edge is the speaker is. If it matter my tweeter is facing on an angle towards my main seating location. 

Or should I leave a gap? Maybe 1”














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## ncabw

ncabw said:


> Can I build a bass trap right beside my rear speakers. I have 16” from back wall to where the edge is the speaker is. If it matter my tweeter is facing on an angle towards my main seating location.
> 
> Or should I leave a gap? Maybe 1”
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They are in wall speakers 


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## HopefulFred

You're good to go.


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## ncabw

HopefulFred said:


> You're good to go.




Perfect


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## ncabw

ncabw said:


> They are in wall speakers
> 
> 
> Sent from my iPhone using Tapatalk




Could I also just do a 24”x14”+- square trap. Any benefits to one or the other? 













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## GibsonES300

Just wanted to share some treatments I've been working on. I had some BAD panels made (about 40, in fact). I'm going to be experimenting with them in my theater as I feel like it is over dampened. Here is the back wall I just finished, as well as the ceiling clouds. 

Next step is experimenting with the side walls. I am optimistic about what I'm hearing so far...


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## Mashie Saldana

GibsonES300 said:


> Just wanted to share some treatments I've been working on. I had some BAD panels made (about 40, in fact). I'm going to be experimenting with them in my theater as I feel like it is over dampened. Here is the back wall I just finished, as well as the ceiling clouds.
> 
> Next step is experimenting with the side walls. I am optimistic about what I'm hearing so far...


Nice, did you have someone drill them out with a CNC machine?


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## GibsonES300

Mashie Saldana said:


> Nice, did you have someone drill them out with a CNC machine?


Exactly


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## ncabw

Can I just add safe and sound in the 4 corners like the picture below? I don’t know if it’s better to cut them in triangles or just rectangle. Rectangle seem so much faster plus more material gets used. So that should be better?? 











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## ncabw

Can I just add safe and sound in the 4 corners like the picture below? I don’t know if it’s better to cut them in triangles or just rectangle. Rectangle seem so much faster plus more material gets used. So that should be better?? 











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## Seltzer33

ncabw said:


> Can I just add safe and sound in the 4 corners like the picture below? I don’t know if it’s better to cut them in triangles or just rectangle. Rectangle seem so much faster plus more material gets used. So that should be better??
> 
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> Sent from my iPhone using Tapatalk


Triangular would be much better


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## HopefulFred

Triangular is a more efficient use of materials, if you are limited by the amount of material you can use or if you are trying to minimize the footprint of the installation. Rectangles will provide better performance.


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## Drelldrell

I have search the forum and internet for this question, but have not found anything conclusive. So thought I would as the question here. I bought my wife a Moviesac from Lovesac as a Christmas gift (see link below). Essentially a beat bag, it is 4’ wide and about 3 1/2' tall, and weighs about 45 pounds. It will filled with shredded durafoam and is covered with at plush cloth type cover. *I am curious if the Moviesac will act as additional acoustic treatment for the room, especially as an additional bass trap. *

Located in a fully finished basement, my "home theater" room is rectangular (about 22'x11') and opens up on the right side to a kitchen and stairway going upstairs. There is also a bedroom behind the room that acts as a workout room. I have several acoustic panels already, including about five bags of dense pack insulation (from Home Depot) in very narrow closet to the left side of the room. Cheap idea that seemed to have tamed bass that seemingly would stand and echo in the closet. 

The Moviesac will be in the back left corner of the room where I currently have a chair. Pics are attached. 

(https://www.lovesac.com/product/item/sacs/moviesac/2108956)


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## ncabw

HopefulFred said:


> Triangular is a more efficient use of materials, if you are limited by the amount of material you can use or if you are trying to minimize the footprint of the installation. Rectangles will provide better performance.




Thanks. 

For now I did the back 2 corners as rectangle 16”x24”

I might do triangles in the front corners because they will look better. 


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## ScottieBoysName

GibsonES300 said:


> Exactly




I’d really like to hear the results of this. I keep hearing everyone rave about diffusion over absorption. Love to see what you think. 

There’s been a lot of talk of diffusion adding “spaciousness”.


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## GibsonES300

Drelldrell said:


> I have search the forum and internet for this question, but have not found anything conclusive. So thought I would as the question here. I bought my wife a Moviesac from Lovesac as a Christmas gift (see link below). Essentially a beat bag, it is 4’ wide and about 3 1/2' tall, and weighs about 45 pounds. It will filled with shredded durafoam and is covered with at plush cloth type cover. *I am curious if the Moviesac will act as additional acoustic treatment for the room, especially as an additional bass trap. *
> 
> Located in a fully finished basement, my "home theater" room is rectangular (about 22'x11') and opens up on the right side to a kitchen and stairway going upstairs. There is also a bedroom behind the room that acts as a workout room. I have several acoustic panels already, including about five bags of dense pack insulation (from Home Depot) in very narrow closet to the left side of the room. Cheap idea that seemed to have tamed bass that seemingly would stand and echo in the closet.
> 
> The Moviesac will be in the back left corner of the room where I currently have a chair. Pics are attached.
> 
> (https://www.lovesac.com/product/item/sacs/moviesac/2108956)


Everything acts as "acoustic treatment" in your room. Every piece of furniture, gear, or human. I wouldn't get too excited about it's effectiveness. Taming low bass with resistive traps takes a lot of volume...


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## GibsonES300

ScottieBoysName said:


> I’d really like to hear the results of this. I keep hearing everyone rave about diffusion over absorption. Love to see what you think.
> 
> There’s been a lot of talk of diffusion adding “spaciousness”.


To make a long story short, so far I like it. At the moment, I have the back wall treated with bad panels of offset depth, the ceiling clouds treated with BAD panels, and the side wall treated with various forms of BAD panels. When I say BAD panels, I mean that I have covered my current traps varying from 6-9" thick with the templates drilled from 1/4" plywood. 

The rear wall and ceilings were a no brainer for me. My room was overly trapped with broadband absorption. The rear wall was slatted with MLS slats and the ceiling clouds were bare. Adding the BAD panels in these areas has helped retain the high frequency energy in the room. Did it make it "spacious"? No, I don't think so. 

The fun part so far has been experimenting with the side walls. For kicks, I temporarily placed BAD templates covering the entire side walls and guess what happened? Magic. Magic happened. I guess it's safe to say that I am in the Toole camp and that I enjoy early lateral reflections. I don't want to use too much audiophile jargon, but if I had to describe it, it was like lifting a blanket off the high frequency details and they spread not only laterally, but also wrapped around, more in three dimensions. Some may call this imprecise, but I don't care. It is far more enjoyable to my ears than absorbing all the early reflections. And the stereo image is very much intact. I don't hear things smearing together. It is only an enhancement of the boundaries and details. 

At the moment, I am experimenting with various forms of arcing the templates into polycylindrical-like shapes. I'm not ready to make a judgement on that yet, although I have some early impressions...


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## ScottieBoysName

GibsonES300 said:


> To make a long story short, so far I like it. At the moment, I have the back wall treated with bad panels of offset depth, the ceiling clouds treated with BAD panels, and the side wall treated with various forms of BAD panels. When I say BAD panels, I mean that I have covered my current traps varying from 6-9" thick with the templates drilled from 1/4" plywood.
> 
> The rear wall and ceilings were a no brainer for me. My room was overly trapped with broadband absorption. The rear wall was slatted with MLS slats and the ceiling clouds were bare. Adding the BAD panels in these areas has helped retain the high frequency energy in the room. Did it make it "spacious"? No, I don't think so.
> 
> The fun part so far has been experimenting with the side walls. For kicks, I temporarily placed BAD templates covering the entire side walls and guess what happened? Magic. Magic happened. I guess it's safe to say that I am in the Toole camp and that I enjoy early lateral reflections. I don't want to use too much audiophile jargon, but if I had to describe it, it was like lifting a blanket off the high frequency details and they spread not only laterally, but also wrapped around, more in three dimensions. Some may call this imprecise, but I don't care. It is far more enjoyable to my ears than absorbing all the early reflections. And the stereo image is very much intact. I don't hear things smearing together. It is only an enhancement of the boundaries and details.
> 
> At the moment, I am experimenting with various forms of arcing the templates into polycylindrical-like shapes. I'm not ready to make a judgement on that yet, although I have some early impressions...


Cool - that's kinda what I was referring to with spacious - that wrapping around that you described. 

Where'd you get the templates done?


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## GibsonES300

ScottieBoysName said:


> Cool - that's kinda what I was referring to with spacious - that wrapping around that you described.
> 
> Where'd you get the templates done?


Friend with CNC access. Check your local craigslist for woodworkers advertising CNC services. A little looking around the web will provide the files they would need...


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## kagtha

900HP said:


> I started the acoustic absorber panel construction for both my room and a buddy's. My room will have all black absorbers with the exception of the side walls which are the red. His side walls are the tan. We have more to do of course and bass traps to build. Just thought I'd share.


Your panels look Amazing!

What are the dimensions and where did you purchase your overlay fabric?

Sent from my Pixel 3 using Tapatalk


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## Mark the Red

Hello All,
Been lurking through this thread and trying to keep my head from exploding with the information.
I am finishing up my home theater and I have a large cavity in the back of the room (vertical) that I am going to fill with insulation as a bass trap. 

It is 12" deep, and wall to ceiling tall (7' tall by 7' wide).

I "overordered" Linaccoustic because I got it for a prayer from a HVAC contractor buddy and have enough to fill it entirely with Linaccoustic via layering

MY question is, would filling this entire void with linaccoustic be better than filling it with Roxul? Or would Roxul / pink fluffy work better a bass trap?

I apologize if my question is noobish, but with this much linaccoustic sitting around I figured I'd get rid of it but was unsure if its properties would work well when layered 11 times thick?

Appreciate the informed answer.


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## sdurani

Mark the Red said:


> Or would Roxul / pink fluffy work better a bass trap?


For 12' thickness, I would do pink fluffy.


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## Mark the Red

sdurani said:


> For 12' thickness, I would do pink fluffy.


OK THanks. I have a bunch of Roxul Saf N Sound already in my basement, but if you recommend the fluffy then fluffy it is. Did you put any kind of plastic over it for particle / fiber control or is the fabric of the panel itself sufficient?


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## sdurani

Mark the Red said:


> I have a bunch of Roxul Saf N Sound already in my basement, but if you recommend the fluffy then fluffy it is.


The thicker the panel, the less dense (better gas flow) the material should be. Besides, pink fluffy is the cheapest insulation you can buy. Just make sure it is not compressed when installed (try to keep if fluffy).


> Did you put any kind of plastic over it for particle / fiber control or is the fabric of the panel itself sufficient?


Fabric panel is sufficient. Plastic membrane helps reflect higher frequencies when you don't want a bass trap to be a full range absorber. But at the middle of the back wall, I prefer all frequencies absorbed. YMMV.


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## 900HP

kagtha said:


> Your panels look Amazing!
> 
> What are the dimensions and where did you purchase your overlay fabric?
> 
> Sent from my Pixel 3 using Tapatalk


Thanks. They are 24"x48" inside. The frames are just 1x4's, 2" of absorber with 1.5" air gap. The absorber mats and the fabric (Guilford of Maine) was purchased from ATS acoustics. They have a nice comparison chart of the various absorption that is available as well. 

Edit: I should also mention that there are 6" thick w/ 4" absorber bass traps on the front wall as well as full-height corner bass traps with 4" absorbent too. There is also Auralex 4" corner fills around the entire ceiling and some Auralex placed in other strategic areas.


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## owl1

Drelldrell said:


> I have search the forum and internet for this question, but have not found anything conclusive. So thought I would as the question here. I bought my wife a Moviesac from Lovesac as a Christmas gift (see link below). Essentially a beat bag, it is 4’ wide and about 3 1/2' tall, and weighs about 45 pounds. It will filled with shredded durafoam and is covered with at plush cloth type cover. *I am curious if the Moviesac will act as additional acoustic treatment for the room, especially as an additional bass trap. *
> 
> Located in a fully finished basement, my "home theater" room is rectangular (about 22'x11') and opens up on the right side to a kitchen and stairway going upstairs. There is also a bedroom behind the room that acts as a workout room. I have several acoustic panels already, including about five bags of dense pack insulation (from Home Depot) in very narrow closet to the left side of the room. Cheap idea that seemed to have tamed bass that seemingly would stand and echo in the closet.
> 
> The Moviesac will be in the back left corner of the room where I currently have a chair. Pics are attached.
> 
> (https://www.lovesac.com/product/item/sacs/moviesac/2108956)


Been planning a wood backing behind our TV just like this. A little OT but do you mind sharing what you used for this? My wife loves it! TIA


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## Drelldrell

owl1 said:


> Been planning a wood backing behind our TV just like this. A little OT but do you mind sharing what you used for this? My wife loves it! TIA


Thanks. We love the wall too. See product below. It’s actualy vinyl plank flooring. Nice texture, not flat.Easy to install. 

https://www.lowes.com/pd/Style-Sele...Peel-and-Stick-Vinyl-Plank-Flooring/999957677


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## owl1

Drelldrell said:


> Thanks. We love the wall too. See product below. It’s actualy vinyl plank flooring. Nice texture, not flat.Easy to install.
> 
> 
> 
> https://www.lowes.com/pd/Style-Sele...Peel-and-Stick-Vinyl-Plank-Flooring/999957677




Thanks! Is the wall really the driftwood color? Yours looks more like mahogany in the picture. 


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## Drelldrell

owl1 said:


> Thanks! Is the wall really the driftwood color? Yours looks more like mahogany in the picture.
> 
> 
> Sent from my iPhone using Tapatalk


It's certainly darker than driftwood out of the box. Color is warmer and closer to mahogany in reality. I also have a darker ceiling that helps maintain the view.


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## mrevo2u

Quick newbie question about OC 703/705. Is the thickness pretty accurate (does 1" thick measure 1" or less like plywood, etc.?) Also, OC's website says 703 is semi-rigid and 705 is very rigid and more durable. For people who have used both; is the 705 more dent/abuse resistant?


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## seplant

I have a drop ceiling in my theater room but the tiles are not acoustic. Can anyone recommend an economical source for black 24x48x2 acoustic ceiling panels? I might end up going with 1" panels if I can't find a good deal on 2" panels.


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## Ladeback

seplant said:


> I have a drop ceiling in my theater room but the tiles are not acoustic. Can anyone recommend an economical source for black 24x48x2 acoustic ceiling panels? I might end up going with 1" panels if I can't find a good deal on 2" panels.


A AVS Member and friend in my area has the Theater Black f tile are this place.

https://www.certainteed.com/commercial-ceilings/products/theatre-black-f/

I priced the tile for my room which is is 14'x26' and it was $324.86 which is about $3.57 a tile. They are 1" in thickness. The track and wire was around $300 for my room. Check out where to buy in your area.

Edit: The price is for 2'x2' tiles, but they sell it in 2'x4' as well. Not sure on the price.


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## seplant

Ladeback said:


> A AVS Member and friend in my area has the Theater Black f tile are this place.
> 
> 
> 
> https://www.certainteed.com/commercial-ceilings/products/theatre-black-f/
> 
> 
> 
> I priced the tile for my room which is is 14'x26' and it was $324.86 which is about $3.57 a tile. They are 1" in thickness. The track and wire was around $300 for my room. Check out where to buy in your area.
> 
> 
> 
> Edit: The price is for 2'x2' tiles, but they sell it in 2'x4' as well. Not sure on the price.


Thanks! Do you know if he is happy with the acoustic properties of these panels?


----------



## Ladeback

seplant said:


> Thanks! Do you know if he is happy with the acoustic properties of these panels?


Yes, he is very happy. He is the one who put me in touch with a local company. That's how I got the prices. I thinking of using them as well if I can figure a way to support Atmos speakers. 

Sent from my SM-N960U using Tapatalk


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## seplant

Ladeback said:


> Yes, he is very happy. He is the one who put me in touch with a local company. That's how I got the prices. I thinking of using them as well if I can figure a way to support Atmos speakers.
> 
> Sent from my SM-N960U using Tapatalk


With my current drop ceiling, I used speakers made for ceiling mounting for my atmos speakers. Mine are Paradigm.


----------



## Ladeback

I asked about that, but they seem to think acoustic panels wouldn't hold.

Sent from my SM-N960U using Tapatalk


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## gupta_ash

I have just started planning the layout/acoustic treatment for the home theater area in the basement. As you see the layout, we have a daylight basement with pretty large space. On one side, we have wet bar/kitchenette and space for pingpong/pool table. The other is where I have projector screen. Right side of that is a passage area going to bedroom behind the projection wall and bathroom.

As I have a window on the left, I am planning to cover that with big panel (or panels). the window is 6' x6'. My plan is to have horizontal panel pretty much covering the entire wall but have sound absorption filling in the middle 4' of the wall. I am planning to use rockwool 3" safe n sound insulation for this. The upper/bottom section would not have any insulation.

Do you think this would be sufficient? Any additional thoughts on the layout? My screen width is going to be around 148" wide.


----------



## bfb1963

*Front Wall Fabric Options for Pink Fluffy? Bedsheets?*

I have 10” of pink fluffy insulation on my front wall for broadband absorption. It is faced on the wall side and stapled to the drywall. It is behind an AT screen. I want to cover it so I don’t get itchy.

Using expensive AT fabric is a waste of money. Black burlap hung vertically from the ceiling in an option, but how to join the sides easily? What about a black bedsheet, which can be a pretty large piece of material and is cheaper than burlap and easier to hang? Bedsheets are tightly woven, but very thin. I assume 100% cotton is probably less reflective than poly/cotton, but does that make any difference?


----------



## ScottieBoysName

bfb1963 said:


> I have 10” of pink fluffy insulation on my front wall for broadband absorption. It is faced on the wall side and stapled to the drywall. It is behind an AT screen. I want to cover it so I don’t get itchy.
> 
> 
> 
> Using expensive AT fabric is a waste of money. Black burlap hung vertically from the ceiling in an option, but how to join the sides easily? What about a black bedsheet, which can be a pretty large piece of material and is cheaper than burlap and easier to hang? Bedsheets are tightly woven, but very thin. I assume 100% cotton is probably less reflective than poly/cotton, but does that make any difference?




Use Milliskin spandex. It’s cheap, durable, and some of the most acoustically transparent material you can get. 

I have the same setup as you and that’s exactly what I did.


----------



## thegeek

What's the fire rating on milliskin spandex? It looks interesting, but if it's not IFR then it's unacceptable to me.

Sent from my VS996 using Tapatalk


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## Mahuzz13

I was hoping someone here has these types of diffusion panels and can help me out. They are 1’x1’ if you could tell in the picture. 









I am building them myself and I was wondering where they are to go in the besides the second row on the ceiling. Do they go beside each column you have speakers in, do they go on either side of the column or just one, if just one side could you explain why. Do you just put one beside the column or do you stack 2 so you would cover a 1’w x 2”h area. 

Thanks for your help in advance


Sent from my iPhone using Tapatalk


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## filmgeek47

mrevo2u said:


> Quick newbie question about OC 703/705. Is the thickness pretty accurate (does 1" thick measure 1" or less like plywood, etc.?) Also, OC's website says 703 is semi-rigid and 705 is very rigid and more durable. For people who have used both; is the 705 more dent/abuse resistant?


Can't speak to the 705, but having just built some 703 panels's I'd say the thickness is pretty much as stated. I built my panel with exactly 2" wide pieces of pine, and the material was pretty much completely flush. Hope that helps.


----------



## mcallister

Mahuzz13 said:


> I was hoping someone here has these types of diffusion panels and can help me out. They are 1’x1’ if you could tell in the picture.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I am building them myself and I was wondering where they are to go in the besides the second row on the ceiling. Do they go beside each column you have speakers in, do they go on either side of the column or just one, if just one side could you explain why. Do you just put one beside the column or do you stack 2 so you would cover a 1’w x 2”h area.
> 
> Thanks for your help in advance
> 
> 
> Sent from my iPhone using Tapatalk


Curious if you have a link to how you’re building these diffusers?


----------



## Mahuzz13

mcallister said:


> Curious if you have a link to how you’re building these diffusers?




I will it will be in my HT build thread, I will update with pictures and descriptions on how I’m doing it. 

When I update my thread I will attach you to the thread to make it easy for you to find it 


Sent from my iPhone using Tapatalk


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## bfb1963

ScottieBoysName said:


> Use Milliskin spandex. It’s cheap, durable, and some of the most acoustically transparent material you can get.
> 
> I have the same setup as you and that’s exactly what I did.


I am using that for my screen. However, its about $100 to cover my 8ft x 14ft wall.

What about furniture cambric dustcover bottom cloth? That stuff is really cheap. That is the stuff put under couches and chairs.


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## asarose247

This diffuser built on standard lattice dimensions- because I had left over lattice

it sits of the top edges of a 3" roxul filled solid backed box.

I went with the textured paper because I wanted some "diversity' of porosity and dispersion vectors

(sounds smart- ow YMMV)

this 2' sq, was for the space atop part of the Submaximus V2 cab as it was directly, NF, behind me
attached using a french cleat and some felt bumpers to avoid any rattling 

now covered in light AT black fabric wrt easier cleaning, etc. 

most of glued down onto the lattice except at the edges where the frame is


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## darrellh44

bfb1963 said:


> I have 10” of pink fluffy insulation on my front wall for broadband absorption. It is faced on the wall side and stapled to the drywall. It is behind an AT screen. I want to cover it so I don’t get itchy.
> 
> Using expensive AT fabric is a waste of money. Black burlap hung vertically from the ceiling in an option, but how to join the sides easily? What about a black bedsheet, which can be a pretty large piece of material and is cheaper than burlap and easier to hang? Bedsheets are tightly woven, but very thin. I assume 100% cotton is probably less reflective than poly/cotton, but does that make any difference?


ScottieBoysName's spandex recommendation sounds like a good idea for containing fiberglass dust, but could you share your reasoning for adding thick absorption behind the screen. I recently pulled my screen out about 14" to place my center channel behind it, and was wondering what I should do with the rest of the empty space. Was the goal to completely deaden your front wall? I've heard this is ok for multi-channel music and movies, but wasn't sure if it's recommended for 2-channel music.

Thanks,
Darrell


----------



## bfb1963

darrellh44 said:


> ScottieBoysName's spandex recommendation sounds like a good idea for containing fiberglass dust, but could you share your reasoning for adding thick absorption behind the screen. I recently pulled my screen out about 14" to place my center channel behind it, and was wondering what I should do with the rest of the empty space. Was the goal to completely deaden your front wall? I've heard this is ok for multi-channel music and movies, but wasn't sure if it's recommended for 2-channel music.
> 
> Thanks,
> Darrell


You are asking the wrong person. I am just parroting those that have gone before me. 

Thick pink fluffy is broad band and best bang for the buck. Others get more innovative, and a lot will use fiberglass board with plastic sheeting since it is narrower profile. I plan to have 6 cyclops 18" subs, so a lot of my wall will actually be obstructed, but not as much as a baffle wall design. I may even add insulation between the speakers/subs.


----------



## sassuki

darrellh44 said:


> ScottieBoysName's spandex recommendation sounds like a good idea for containing fiberglass dust, but could you share your reasoning for adding thick absorption behind the screen.[...]
> 
> 
> 
> Thanks,
> 
> Darrell



The front wall absorption is done to reduce SBIR. https://www.gikacoustics.com/speaker-boundary-interference-response-sbir/
A lot of people use the duct liner material (I forget the name), but if you have the space, pink fluffy or some other type of broadband absorber between the wall and speakers should offer similar benefits. The difference being that you then have to cover the pink fluffy with something, whereas the duct liner could be left exposed.


----------



## darrellh44

sassuki said:


> The front wall absorption is done to reduce SBIR. https://www.gikacoustics.com/speaker-boundary-interference-response-sbir/
> A lot of people use the duct liner material (I forget the name), but if you have the space, pink fluffy or some other type of broadband absorber between the wall and speakers should offer similar benefits. The difference being that you then have to cover the pink fluffy with something, whereas the duct liner could be left exposed.


Thanks for the response. I already have a layer of 2" OC703 covering the full area just behind the screen. I guess what I'm asking is it ok to fill the 1 foot space between the 703 panels and front wall with pink fluffy and/or Ultratouch cotton? Is it possible to over-deaden the front wall?

Thanks,
Darrell


----------



## ScottieBoysName

darrellh44 said:


> ScottieBoysName's spandex recommendation sounds like a good idea for containing fiberglass dust, but could you share your reasoning for adding thick absorption behind the screen. I recently pulled my screen out about 14" to place my center channel behind it, and was wondering what I should do with the rest of the empty space. Was the goal to completely deaden your front wall? I've heard this is ok for multi-channel music and movies, but wasn't sure if it's recommended for 2-channel music.
> 
> 
> 
> Thanks,
> 
> Darrell




Spandex worked awesome for me. I had a cavity to fill up. Otherwise I wouldn’t have done it. You can see the progression in the pics. Last one is with my velvet panels in place.


----------



## darrellh44

ScottieBoysName said:


> Spandex worked awesome for me. I had a cavity to fill up. Otherwise I wouldn’t have done it. You can see the progression in the pics. Last one is with my velvet panels in place.


Great looking room!!! Did the room sound better after you filled the cavity?


----------



## ScottieBoysName

darrellh44 said:


> Great looking room!!! Did the room sound better after you filled the cavity?




Thank you!!

Yeah. I need to re-run Audyssey for sure, but it got rid of some echo.


----------



## ereed

darrellh44 said:


> Thanks for the response. I already have a layer of 2" OC703 covering the full area just behind the screen. I guess what I'm asking is it ok to fill the 1 foot space between the 703 panels and front wall with pink fluffy and/or Ultratouch cotton? Is it possible to over-deaden the front wall?
> 
> Thanks,
> Darrell


If you overdead the wall make sure you are not just overdeading the mid/high freq but get it as thick and absorb low freq as much as possible as well. From home theater standpoint, I've heard its best to have dead front wall but opposite for 2 channel music playback. 

Currently I have just broadband panels behind the LCR only and not whole front wall treated....may try to stuff few cavities from fireplace and tv nook (which is behind screen) for additional bass trapping either using pink fluffy or roxul.


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## darrellh44

ereed said:


> If you overdead the wall make sure you are not just overdeading the mid/high freq but get it as thick and absorb low freq as much as possible as well. From home theater standpoint, I've heard its best to have dead front wall but opposite for 2 channel music playback.
> 
> Currently I have just broadband panels behind the LCR only and not whole front wall treated....may try to stuff few cavities from fireplace and tv nook (which is behind screen) for additional bass trapping either using pink fluffy or roxul.


Thanks for confirming about room treatments for 2-ch vs multi-channel playback. This is what I had gathered from the discussion in the first few pages of this thread by Dennis Erskine and others - I just wasn't sure if this was still the general consensus. 

My plan is to expand 2-ch sources to 5.1 (LCR+front-wides) with audio processing to create the reverberate field. Unless someone says it's a bad idea for my setup, I'm going to go ahead and add as much broadband absorption as I can to the front wall behind the screen (12" deep) and much thicker (20+") in the front corners floor to ceiling. For materials in addition to the 2" OC703 directly behind the screen, I plan to add a layer of 5" Ultratouch batting against the entire front wall (mainly because I've already purchased it), and then fill the remaining spaces behind the screen and in the corners with pink fluffy. And of course I'll include the spandex where needed to contain the pink fluffy stuff.

Thanks,
Darrell


----------



## Buzniak

Is having solid wood floors a bad idea or can it be dealt with?


----------



## HopefulFred

Buzniak said:


> Is having solid wood floors a bad idea or can it be dealt with?


Generally, it's a problem to be overcome. Parallel surfaces that are both hard and reflective (common ceilings and wooden floors) are a recipe for flutter echo.


----------



## AndreNewman

I have solid wood on concrete floors and I’d like to reduce the reflections. We have a big rug between the front speakers and our listening position but I’d like to put some underlay under the rug to absorb a little more. My partner wants to keep this rug but it’s a little thin, just a regular wool carpet thickness.

My first thoughts are a wool underlay I suspect the foam ones will be a little strange to walk on under a rug.

Does anyone have any data or experience as to what sorts of underlay works for this purpose? Or even if it makes any difference at all?


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## ncabw

Do any of these products have any use for helping with sound reflections? 

I have a 4x9 sheet of this 










And then a roll 4’x60’ of this product 












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## thegeek

My room is 16' w, 18.5' d, and 8.5 to 12' high depending on how you measure because it's false tray ceiling covering a vaulted ceiling under a hip roof.

I've come to the conclusion that I want diffusion for the first reflection points. I'm going to have it attached to bare walls and then covered with AT fabric done as drapes because reasons, and I've got about 2 inches to play with. I know, 2 inches of depth isn't much in the world of acoustic treatments, but just go with it.

So, my question is what is my best bet here? I'm going diy. Option 1 is a poly curve diffuser because they look effective and easy to build. Option 2 is one of these new-fangled abfusor thingamajigs where you put randomly spaced random width slats over an absorbtion panel. I'm not quite sold on the concept, but I'm willing to be convinced.

I'm also open to other options, like I could build QRD or skyline, but given the depth I'm unsure that's the best idea. Maybe skyline with random angle cut faces?

Sent from my VS996 using Tapatalk


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## asarose247

@thegeek

not sure how much homework you've done,
Ethan Winer has a good video about them
and

but this looked interesting

https://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/469065-d-i-y-polys.html


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## thegeek

My guess is that the shallow skylines are a no go. My thinking at this point is that at lower frequencies something that shape looks like a flat surface, angles or not.

I had seen that link before on the poly construction, but it's a good one. There's a lot of good ideas in there and it's a good one to follow. I'll go hunt down the vid from Ethan. Thanks!

Sent from my VS996 using Tapatalk


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## bpape

thegeek said:


> My room is 16' w, 18.5' d, and 8.5 to 12' high depending on how you measure because it's false tray ceiling covering a vaulted ceiling under a hip roof.
> 
> I've come to the conclusion that I want diffusion for the first reflection points. I'm going to have it attached to bare walls and then covered with AT fabric done as drapes because reasons, and I've got about 2 inches to play with. I know, 2 inches of depth isn't much in the world of acoustic treatments, but just go with it.
> 
> So, my question is what is my best bet here? I'm going diy. Option 1 is a poly curve diffuser because they look effective and easy to build. Option 2 is one of these new-fangled abfusor thingamajigs where you put randomly spaced random width slats over an absorbtion panel. I'm not quite sold on the concept, but I'm willing to be convinced.
> 
> I'm also open to other options, like I could build QRD or skyline, but given the depth I'm unsure that's the best idea. Maybe skyline with random angle cut faces?
> 
> Sent from my VS996 using Tapatalk


The AT fabric when pleated will no be AT any more. The 2" depth will only diffuse relatively high frequencies which the fabric will end up absorbing a lot of. If you want to use diffusion for reflections I would highly recommend QRD style but more like 6" thick to get down into the 300ish range.


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## thegeek

Standard drapery back and forth pleats, yeah I can see that being a problem since incidental waves are trying to punch though several layers. AT isn't so T raking through from the side of that.

Take a look at these pleats though: http://soundfold.com/product/fabric/

It's essentially flat for most of the run with just some ribs sticking up.

Sent from my VS996 using Tapatalk


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## asarose247

while not exactly an acoustical issue

the black out being achieved . . . looks great
anybody have any info / data / experience 
wrt 
the black out qualities of 
royalty velvet #3 compared to "regular" 16 oz. duventyne fabric?


----------



## bpape

In pro applications Duvetyne is used. Velvet pretty much always has some sort of 'sheen' to it.


----------



## asarose247

^
TY, in anticipation, I have a rather large piece of the D for future ceiling application.


----------



## asarose247

some "not quite scientific" but pics of some reflective(?) darkening(?) absorptive properties of

royalty velvet#3 on the hanging from top left
duventyne , standard, on the right, similarly

the bottom triangle piece showing thru is black speaker cloth on the face of this mobile and "tunable" 1st reflection pt. panel.

the object is to get the ceiling in the mancave blacked out even more
duventyne is an industrial go-to 

any comments appreciated, PM's good too

pics taken under obvious lighting differences


----------



## thegeek

Wow it's not even a contest here as the duvetyne looks like a medium gray next to the velvet. What was your source for this exact velvet?

Sent from my VS996 using Tapatalk


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## asarose247

^ that is Jo-anns royalty velvet #3 ,
now i'm wondering if I should return the d'tyne to amazon

if you sign up for coupons from Jo-anns, you can save a bundle , takes some timing and lurking

i intend to use a spray / fabric / elmers glue/ adhesive to get the material attached to my 3/16ths ply 

TY


----------



## DeruDog

*7.1.4 treatment design*

Hi all. I am just getting in to the design stage of a 7.1.4 surround room. It has issues (don't they all) such as windows that I will have to treat. Below are some renderings I have done of my plan and a photo of the current room.

The plan will be to treat the 1st reflection points to the greatest degree possible, or practical while maintaining something that looks fairly good. One question I have is what thickness/product to use for 1st reflections. Should I treat reflections for surround and atmos speakers differently than the front and center ones? My plan was to use 2" 703 at all points, though if that is overkill I would rethink.

I will be using Bass traps at the corners, though I have not settled on how thoroughly that will be done. Currently I think floor to ceiling traps with a 2 foot face, probably OC 703.

For the render below, the blue squares show the 1st reflection points for all speakers at the left, right, and center seating positions on the couch. Obviously, there are a lot of positions to cover. I would not just treat the little squares, instead, those would be my focus areas for 2x2 or larger panels.

Please let me know what your thoughts are.


----------



## sdurani

The problem with using thin absorbers is that they absorb mostly mid to high frequencies and not much in the lower frequencies, which turns them into elaborate tone controls rather than broadband absorption. 2" OC703 is good down to about 300-400 Hz. For broadband absorption, you'd need 6" on the wall or 4" spaced 4" from the wall (4" air gap). I would start with absorption on the front and back walls, since sounds from those directions can muddy the soundstage. Sounds reflecting off the side walls are outside the front soundstage and aid in spaciousness, so absorbing those reflections is optional.


----------



## asarose247

Hth


----------



## asarose247

@thegeek

grinding relentless ever onward . . .
suppose .. .

as of today, the Joanns is 13.99 yd, on line order, 44" wide

however, amazon :Ben Textiles Royal Velvet Black Fabric by The Yard 58" wide, 8.60 /yd- 30% mol wider , bout 30% cheaper

now there is stretchy velvet for lower prices but the concept of stretchy would require more secure mounting
and possible glue burn-thru and a ability for "unstretched / un stressed application, to a supporting backing, I would presume.

I have a Walmart near me, (but then again who doesn't?) so I may take one for the team and get a sample if they have something that looks feasible . . .
I am however returning the D'tyne to Amazon.

I probably need about 11 sq. yds for the room so looking to avoid really overthinking this . .

I'll take some more pics . .


----------



## thegeek

A long time ago I was reading an article about Experimental Aircraft, aka kit planes. There are very dedicated hobbiests who construct their own personal airplanes from kits and plans. The author of this article was interviewing one of them and asked how much it costs to build one and the builder stated pointing at different pieces of their aircraft while quoting hours to build, not dollars. For them the real cost was time.

Back then I thought this was odd, but now I have a truer understanding of that man's mindset.

My build thead was started in 2006 and I'm still not done. Life happened between then and now and any time on this project is time that's not spent elsewhere. Other hobbies have shown up old hobbies have reappeared, many other projects came before me and we're slain, three children were born and the youngest is now 6. We live in Central Florida and let's just say our kids are experts at theme parks. I sank months into their rooms. Two of their rooms are murals that I've hand painted, one has a room that's almost completely trimwork. Career just won't stay in its spot and keeps crossing the line into personal time...

Time is my true cost and the family wants this thing done. I'm at the point where I don't care anymore, but it's been no compromises so I'm not letting up. I've recently swapped over the speaker choice from the Martin Logans that have been waiting in the closet for ten freakin' years to DIY SG speakers behind an AT screen. I've seen the light on planars and ribbons, and the answer is "no". As a system they're just plain better for theater use being listened to by multiple people in an actual room. It's costing me a few months of my spare time but it will be better in the end as dipoles were a dumb choice on my part. I am customizing then to my exact use, something I'd be crazy to do with a Klipsch Ultra2 setup. It's still costing me a bundle of time though.

There are things I can build cheaper and I can squeeze costs out of, but hemming and hawing on the precise fabrics for a possible slight difference in cost with the Walmart choice versus the Joanne's probably isn't a big difference. Maybe one really is better? When evaluated in terms of time the Joanne's fabric looks like it's really good, and easily sourced by ordering online. You've done me a great service in evaluating velvet versus duvetyne, but spending a few hours at taking a swing at a chance of trimming $20 might not be a good trade-off. I get it as this sure isn't a cheap hobby, but money isn't the only price we pay for what we want to have.

Sent from my VS996 using Tapatalk


----------



## asarose247

your logic is unassailable -
the difference is about $0.50 / ft^2, and this is for about 100 ft^2 max.

and I already own a few yards . .of the velvet
the returned d'tyne will be about $40
$50 after what I've already spent-?
I've given away many times that in an effort to clear (just didn't cut it) things out

TIME is the most expensive factor.

I'll keep watching Joanns and once I get an MO for sizing the panels I'll attach to the stringers, then it's a go

Seems like a Cutsheet puzzle . .

mantra: You're not done yet

TY


----------



## jcmccorm

thegeek said:


> A long time ago I was reading an article about Experimental Aircraft, aka kit planes. There are very dedicated hobbiests who construct their own personal airplanes from kits and plans. The author of this article was interviewing one of them and asked how much it costs to build one and the builder stated pointing at different pieces of their aircraft while quoting hours to build, not dollars. For them the real cost was time.
> 
> Back then I thought this was odd, but now I have a truer understanding of that man's mindset.
> 
> My build thead was started in 2006 and I'm still not done. Life happened between then and now and any time on this project is time that's not spent elsewhere. Other hobbies have shown up old hobbies have reappeared, many other projects came before me and we're slain, three children were born and the youngest is now 6. We live in Central Florida and let's just say our kids are experts at theme parks. I sank months into their rooms. Two of their rooms are murals that I've hand painted, one has a room that's almost completely trimwork. Career just won't stay in its spot and keeps crossing the line into personal time...
> 
> Time is my true cost and the family wants this thing done. I'm at the point where I don't care anymore, but it's been no compromises so I'm not letting up. I've recently swapped over the speaker choice from the Martin Logans that have been waiting in the closet for ten freakin' years to DIY SG speakers behind an AT screen. I've seen the light on planars and ribbons, and the answer is "no". As a system they're just plain better for theater use being listened to by multiple people in an actual room. It's costing me a few months of my spare time but it will be better in the end as dipoles were a dumb choice on my part. I am customizing then to my exact use, something I'd be crazy to do with a Klipsch Ultra2 setup. It's still costing me a bundle of time though.
> 
> There are things I can build cheaper and I can squeeze costs out of, but hemming and hawing on the precise fabrics for a possible slight difference in cost with the Walmart choice versus the Joanne's probably isn't a big difference. Maybe one really is better? When evaluated in terms of time the Joanne's fabric looks like it's really good, and easily sourced by ordering online. You've done me a great service in evaluating velvet versus duvetyne, but spending a few hours at taking a swing at a chance of trimming $20 might not be a good trade-off. I get it as this sure isn't a cheap hobby, but money isn't the only price we pay for what we want to have.
> 
> Sent from my VS996 using Tapatalk


Off topic a bit, just chiming in to say that your post was well stated, start to finish. At 54 years old, and being a grandpa now, that stuff hits home (hobbies coming and going, kids, work, life, etc.)

I like to shave a buck where I can like the rest of us. Sometime it's ok to spend extra time though. I actually enjoyed putting speakers together and building my own room treatments. That's *my* time that I enjoy. Some things though I don't waste time with. And what a coincidence, one of those things was the fabric for treatments. I went with GoM. It wasn't cheap, but it looks good and works. 

I've got a good buddy who's one of those guys that built his own plane (he's taken me up in it a few times). You're right, it's time. Of course, he can't count the dollars or he'd make himself ill. 

I grew up in Central Florida too; Casselberry. Me and The Mouse are old friends 

What DIYSG speakers did you decide on? I did HTM-12's myself.


----------



## kgveteran

DeruDog said:


> Hi all. I am just getting in to the design stage of a 7.1.4 surround room. It has issues (don't they all) such as windows that I will have to treat. Below are some renderings I have done of my plan and a photo of the current room.
> 
> The plan will be to treat the 1st reflection points to the greatest degree possible, or practical while maintaining something that looks fairly good. One question I have is what thickness/product to use for 1st reflections. Should I treat reflections for surround and atmos speakers differently than the front and center ones? My plan was to use 2" 703 at all points, though if that is overkill I would rethink.
> 
> I will be using Bass traps at the corners, though I have not settled on how thoroughly that will be done. Currently I think floor to ceiling traps with a 2 foot face, probably OC 703.
> 
> For the render below, the blue squares show the 1st reflection points for all speakers at the left, right, and center seating positions on the couch. Obviously, there are a lot of positions to cover. I would not just treat the little squares, instead, those would be my focus areas for 2x2 or larger panels.
> 
> Please let me know what your thoughts are.


For my 7.1.4 room i did 4”OC703 on the ceiling for the FRP for LCR LS RS, I couldn’t get the RB LB done because of the projector placement.
The sidewalls are 10” fluffy OC. The corners are 2’x2’x8’ superchunk fluffy pink OC
The remaining parallel walls have Diffusers, they are wooden DIY along with acouple skyline (also diy). No flutter echo in my room
I left the Atmos alone, they are hanging svs prime satillites......

The room will sound very different which is why people will say it sounds “Dead”, NO it sounds treated LOL not an echo chamber :0)

My backwall is actually a 600lb acoustic door i designed and built, it has 4”OC in it, yup 600lbsPlus

And the BR and BL are on rollers so the door can be put into place :0) CrazyRoom
Good luck and have fun


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## ComradeBrehznev

DeruDog said:


> Hi all. I am just getting in to the design stage of a 7.1.4 surround room. It has issues (don't they all) such as windows that I will have to treat. Below are some renderings I have done of my plan and a photo of the current room.
> 
> The plan will be to treat the 1st reflection points to the greatest degree possible, or practical while maintaining something that looks fairly good. One question I have is what thickness/product to use for 1st reflections. Should I treat reflections for surround and atmos speakers differently than the front and center ones? My plan was to use 2" 703 at all points, though if that is overkill I would rethink.
> 
> I will be using Bass traps at the corners, though I have not settled on how thoroughly that will be done. Currently I think floor to ceiling traps with a 2 foot face, probably OC 703.
> 
> For the render below, the blue squares show the 1st reflection points for all speakers at the left, right, and center seating positions on the couch. Obviously, there are a lot of positions to cover. I would not just treat the little squares, instead, those would be my focus areas for 2x2 or larger panels.
> 
> Please let me know what your thoughts are.


I personally would not worry about treating the surround and Atmos speakers. You do want *some* liveliness in the room after all. For some ideas feel free to flip through my construction photos. I have GIC bass traps behind the main L/R and GIC panels on the side walls and ceiling. Cheers https://www.blu-ray.com/community/gallery.php?u=245268


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## asarose247

@thegeek, @Marc Alexander

The rabbit hole may much bigger than we dare allow ourselves to fear-
Here's hope - maybe not so much from me

The Chase for LESS light at the end of the tunnel . .

the bit of comparative , dare I say instead – darknessing (capability)

check back a few post to the 1st set of pics, slightly different lighting

these
on the right – Royalty velvet #3 same piece
left is relatively less expensive, black velvet sample I thought looked promising, from Amazon vendor. it's back is way much stiffer- 
not the slight give of the fabric- possible plus
and sitting here looking thru the backs at the TV, by holding it up in front of me the new stuff
So I just draped them over the TV. 1st is the #3 , then the other, 
#3 looks better but is that "lesser transparency a real factor for this ceiling blackout use 

the new stuff depending on light may not look as deep a black as the other but it does seem to be "less bright' or less reflective, less "glossy"
so is that a good thing, and so forth

So, campers - any feedback?


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## thegeek

That's the Royal Velvet #3 with the major sheen?

For my use on the walls and ceiling I'm going with black DMD fabric from Acoustimac. I need black without sheen, and acoustically transparent, which this stuff nails. While I'm 1000% certain I like it more than your standard GOM material I'm not so sure about using it in lieu of velvet because of the texture.

They DO make a "castielle suede" material that comes in black. There's a bit of sheen to it, but the question come in how it compares to the other stuff. Might be too much of a sheen though, but my observations aren't valid without context versus the other stuff. Also, for some reason I can't find the black, navy is the darkest I'm looking at in my sample pack.

Sent from my VS996 using Tapatalk


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## asarose247

^ TY
ordered the sample pack of castielle suede,

so may try another set of pics 

thanks for reminding me of the word "sheen'


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## ereed

Looking for some input here. My room is treated with GIK panels. But I have a specific question about the front wall behind the screen especially the fireplace and TV nook. Should I fill those in with pink fluffy, or other material? Not sure if it makes a difference having those 2 things exposed or closed? Here is picture of my actual room currently and here is what it looks like behind the screen to show what I'm talking about (old picture during beginning phase prior to black velvet).


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## thegeek

@asarose247

I was going through old bookmarks was was em reminded of the existence of "fidelio" velvet, as discussed here: https://www.avsforum.com/forum/19-dedicated-theater-design-construction/2821049-fidelio-velvet.html

Sent from my VS996 using Tapatalk


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## asarose247

never mind the left sample- way too much sheen, Walmart , like $4 /yd. nice but not for this

right is #3 

backdrop piece the other aforementioned piece from Amazon

any suggestions?


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## thegeek

It looks like the random stuff from Amazon is winning so far. It's almost as dark as last night's episode of Game of Thrones.

Sent from my VS996 using Tapatalk


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## GoZags13

Does anyone know if you can get the Owens Corning 703 from common hardware stores (lowes, home depot, ace, etc)? Or a similar insulation for building your own absorbers? I know GIK sells it on their site but I'd rather just pick stuff up in person and save on shipping if possible.


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## Gradenko

thegeek said:


> It's almost as dark as last night's episode of Game of Thrones.


Zing!


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## asarose247

short version, no pics
the amazon stuff shed way too many surface fibers with a adhesive lint removal roller while cleaning up for clinging dust, sawdust, ,
showed compression "artifacts" from the small clamps I used to hold for positioning and tensioning while stapling, 
and showed "bruising' when i used a hammer to set the tacks evenly, since they rest up against the ceiling stringers
trying to be as smooth and flat as I can
uneased edges / corners of the ply "challenged"the backings integrity , becoming transparent / tearing slightly
the 2 sided tape created a textural anomaly, but that was on the 1 strip where I tried using a wallpaper seam roller for better contact.
(of course i could paint the wood black on the edges and I may do so)

OTOH, the #3 does not shed anything, comparitively, but that's as far as I got with that for today.
It would probably vacuum clean also
all edges and corners will be eased

Question?> could the #3 hold well enough using 2" wide double sided carpet tape
the entire perimeter would be 1" with it wrapped around to the back for another 1" ,mol, of hold
the tape might also reduce and tendency for the backing to "reveal'
i couldn't paint the tape at the edges, maybe a fat shapie, just a line

there will be closely spaced strips / squares of the tape in the interior area of the panel, just so the whole of the fabric is not inclined to sag, owning to the fact of no interior area "support

OTOH, the one panel of the amazon stuff is black with the lights out and all the aforementioned problems become kina of a moot point. maybe not worth the headaches, tho.

but I will go with the #3 , I have 3 pieces cut for 3 of the larger panels but have to wait to put up the new ceiling fan .


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## Drelldrell

I have a question about what I will define as bass traps that I have installed in my family room/home theater. (in the fully finished basement). Installing bass traps in the corners is not ideal for a number of reasons. It would look out of place and wife will give me grief. And the room opens to a downstairs a summer kitchen and stairway leading upstairs. The family room area is approximately 25Lx11Wx7H, if I recall correctly. I have a two SVS PB-2000s. 

I have a rather good amount of acoustic panels. This weekend I made two 7’x15” panels that are 3” thick. I used Owens Corning Thermafiber Fire and Sound Guard Mineral Wool Insulation. I am calling these bass traps but they actual do a really good job of hiding wires at the base of the floor. I am curious if they act at all like a bass trap where the floor and wall intersect. I have similar, but slightly smaller, bass traps behind the seats at the floor to wall intersections. 

I have bass traps in the left two corners of the room, but they on are about 40” tall, although about 4” thick. 

Will re-run Denon calibration tomorrow to see what (if any impact) occurs. Curious to what you all may think on the board.


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## thegeek

It's a living room not a dedicated theater, there only so much to can do and aesthetically you've done a bang up job.

That said it appears like you're got the subs in the corners which are the worst places possible you can put a sub. Go ahead and run your tests, but next place each sub in the space between your mains and the equipment console and see how that changes things.

Sent from my VS996 using Tapatalk


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## AndreNewman

Drelldrell said:


> I have a question about what I will define as bass traps that I have installed in my family room/home theater. (in the fully finished basement). Installing bass traps in the corners is not ideal for a number of reasons. It would look out of place and wife will give me grief. And the room opens to a downstairs a summer kitchen and stairway leading upstairs. The family room area is approximately 25Lx11Wx7H, if I recall correctly. I have a two SVS PB-2000s.
> 
> I have a rather good amount of acoustic panels. This weekend I made two 7’x15” panels that are 3” thick. I used Owens Corning Thermafiber Fire and Sound Guard Mineral Wool Insulation. I am calling these bass traps but they actual do a really good job of hiding wires at the base of the floor. I am curious if they act at all like a bass trap where the floor and wall intersect. I have similar, but slightly smaller, bass traps behind the seats at the floor to wall intersections.
> 
> I have bass traps in the left two corners of the room, but they on are about 40” tall, although about 4” thick.
> 
> Will re-run Denon calibration tomorrow to see what (if any impact) occurs. Curious to what you all may think on the board.


I'm interested to hear how this goes, I'm considering something similar around my screen. I need to black out the ~half meter around my screen and would be good to get bass traps out of the project too. Mine would be like yours but 45 degrees, a big wider and above the screen to the ceiling too.

Can you hear the difference if you take them away temporarily?


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## sdurani

Drelldrell said:


> I am curious if they act at all like a bass trap where the floor and wall intersect.


The air gap in the corner behind the panel will help, but three inches of that material will absorb down to a couple hundred Hertz while four inches will get you closer to a hundred hertz. Which means that the bass being absorbed will be from your speakers, above the crossover point, not bass from your subs (the lowest frequencies would require absorption several feet thick). 

Also, you'll have to cover significant surface area to have any effect. There is 1,054 square feet of surface area in your room. Your two 7' x 15" panels have 17.5 square feet of surface area. Will covering 1.7% of the surface area of your room have noticeable effect on bass? If you add in your other "bass traps", will it amount to even 5% of the surface area of your room?


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## Drelldrell

thegeek said:


> It's a living room not a dedicated theater, there only so much to can do and aesthetically you've done a bang up job.
> 
> That said it appears like you're got the subs in the corners which are the worst places possible you can put a sub. Go ahead and run your tests, but next place each sub in the space between your mains and the equipment console and see how that changes things.
> 
> Sent from my VS996 using Tapatalk


Thanks for the reply. I have tried to work as much as possible given the room use. I have not ran bass test again. With the leftover OC, I made a 6'x2'x6" [massive] panel that I placed behind the seating (horizontally and angled backwards to wall). 

I watched a movie this weekend and bass seemed better, i.e. a bit more firm and tight. It was actually good before so improvements seems smaller as I have made tweaks. 

Will run test in next day to two and report back.


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## Drelldrell

sdurani said:


> The air gap in the corner behind the panel will help, but three inches of that material will absorb down to a couple hundred Hertz while four inches will get you closer to a hundred hertz. Which means that the bass being absorbed will be from your speakers, above the crossover point, not bass from your subs (the lowest frequencies would require absorption several feet thick).
> 
> Also, you'll have to cover significant surface area to have any effect. There is 1,054 square feet of surface area in your room. Your two 7' x 15" panels have 17.5 square feet of surface area. Will covering 1.7% of the surface area of your room have noticeable effect on bass? If you add in your other "bass traps", will it amount to even 5% of the surface area of your room?


Thanks for the reply. I actually have a total 19 panels disbursed across the room. This is about 102 square feet or closer to 10%. The panels range from 1" to 6" as I just added a 6'x2'x6" panel with left of OC rock wool. Most are in the 1-2" thickness and have helped significantly with high and midrange sound. 

I also have a large closest to the left of the room to which I have several bags of cellulose insulation in large canvas bags. Cheap experiment that I felt was very beneficial as that closet seemed to have bass that just resonated inside and affected the room. In my opinion, the biggest bang for my buck return on things I have done to perfect and imperfect space. 

Think I have done all that I can do short of literally stripping down walls and starting a turn home theater room build. That will not be happening anytime soon!


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## asarose247

Final Trial

Beginning to see , or not, the light

big panel, #3 , the other the aforementioned amazon velvet 

#3 cleans more easily, has enuf bulk, so no staple point show thru, no 'artifacts" from the double sided tape, less stretch , no edge show thru while tightening for final assembly

(more obvious in the 3rd pic), consistently blacker looking in 2 differently shaded outdoor lighting conditions

nowjust need to check how to use the self tapping panhead screws going thru the velvet and not create a problem- pre-drilling and a slight puncture to start thru

I also scored a 50% off coupon from Joann's , so " only' $10 / yd .


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## asarose247

some last thoughts /tips before entering production mode

the mounting holes for each panel laid out and drilled before covering
some panels will take 4, others 6, others 8
keep track of where the holes are-DUH!

I use an icepick to re-find those holes , after covering
poking thru the good side.
that spot i make with a silver sharpie dot that disappears under the panhead,

which have been spray painted- black , of course

i reverse the icepick to the good side try to enlarge the fabric hole

my tests of bare-ass trying to put a 5/32 hole straight thru the fabric- https://www.avsforum.com/forum/images/smilies/rolleyes.gif
you can do it- but you won't like it.
a few times the fabric twisted up so tight it loosened the keyless chick , pulled out the bit

it's important to be sure that the backside fabric at the hole gets a few extra stabilizing staples. the tape alone > won't

from the pic, in the back left corner- 2 slightly different angles blacker than the flat black paint
that's just f'n swell . . but a problem for the next run of the rabbit hole
I'll finish all panels first , 15 to go, and report back.
I'll be working from the center of the room ,from around the ceiling fan , out to the edges.
gives me wiggle room for adjustments


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## Shape of Grey

*Room help...*

Long time lurker, first time poster in this section.

I had recently finished my first attempt at a small theater (13x10 spare bedroom) and now that my honeymoon of a 120” screen is fading, I want to tackle some treatments.

I will attach the layout of the room at the bottom, as well as the current placement of screen.


*Quick description of the setup:*

Room is 9’11x13’ with a small closet (~3’x3’) in the back right of the room which houses the AV equipment; I have removed the door in order to have IR access as well as mitigate some vibrations. On the right wall, at approximate midpoint there is a 6’x6’ window. The door to the room is on left wall at the back of the room (grrrrr). The screen is a 120” 16:9 spandex hung on a frame in-front of the exterior wall (currently not dry-walled/open insulation, wrapped in velvet). Behind the screen are 3x DIYSG HTM10’s; there’s roughly 6” of air gap between the false wall and the back wall insulation. Subs are 2x sealed DA 18-22 Ultimax in 4cuf boxes at the ¼ and ¾ on the front wall. Ls/Rs, Rear L/R are RSL CG3’s hung roughly 1’6” above ear-level, canted towards the MLP.The front and right walls are exterior walls with insulation. Back and left walls are interior with no insulation. Ceiling goes to the attic and is insulated.

Basically, this room is an acoustical nightmare, sound and bass feel muddy; bass is missing that punch...especially for having 2 18” subs in a room that size.

*Now to the meat and potatoes of this mess. Here are some things I was thinking about tackling based on everything I’ve read on the forums over last couple of months.*
*1.* Add some absorption panels directly behind the MLP/couch on the back wall, maybe something like 4” or 6” frames of OC 703 (suggestions?). This may get messy as part of the wall behind the right side of the MLP is an open closet...but I’ll get to that later on.

*2.* BASS TRAPS! Ugh this is going to be tough. If you look at my masterpiece of a drawing below (being facetious, please don't stone me), the only place where I could do a proper wall to ceiling trap (2x4 sheets of material cut into 4 triangles) is the back right corner. The back left, due to the door placement I have about 4” of room to work with on the left wall….so unless I make movable traps, I don't think it’s going to happen. Now the front...while not as terrible as the back left, it’s not great. I only have about 8” of space between the edge of the AT screen and adjacent wall, a far cry from what a “standard” 24” that would be taken up by the triangle trap. 
* Possible workarounds:*
a.Make the traditional triangle corner trap, but carve the inside corner to accommodate the screen or cut the corner in an odd shaped triangle to fit...Both ways seems kind of wasteful but I will leave that for you guys to decide.
b.Fill the cavity behind the screen and the corners with absorption material, making a wall-sized trap...I can take out the pink R-13 OC insulation on the exterior wall and replace it with something more absorbent if needed/possible which would give me total of ~10” of material depth.

*3.* First reflections. Of all my problems, I think this would be the easiest to deal with. For LCR - 2’x4’x2”/4” OC 703 framed with an inch air-gap. Part of my solution for the window was to build a 6’x6’ frame filled with 4” OC 730 hung on cleats over the window to double as blackout material as well as an absorption panel. For ceiling, similar solution of 2’x4’x2”/4” OC703 frames on cloud-mounts.

*4.* Lastly...the dang closet. I haven’t measured, but that thing seems to collect bass like it is it’s job. Should I put the door back (replace with solid core) or is there another/better way to deal with it? Treat with panels? Fill it with material (could get expensive).

Ok, I think this is everything I can think of for now, hopefully this wall of text makes sense. Basically, I have no delusions that this is a great room for HT setup. Unfortunately, this is what I have to work with and I want to make the best of it in a way that makes the most cost/benefit sense.

What do you guys think? What would you suggest and how would you go about implementing it. What should I prioritize?

Attached is my finger-painted rough layout of the room.

~cheers


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## audiosq

Would it be better to do 2'x2'x6" traps in the top of the corners where it meets the ceiling or to use bigger 2'x4'x6" traps in the middle of the corners. I would say the top measures about 7 db louder than the middle at the corners. I can't fit the four foot traps in at the top due to speaker placement and a door. Thanks!


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## Craig Gordon

One main thing you can do is move your seating position (couch) about 2 to 2.5 feet forward. It is currently too close to the back wall. And where are those giant subwoofers currently located?


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## Shape of Grey

Craig Gordon said:


> One main thing you can do is move your seating position (couch) about 2 to 2.5 feet forward. It is currently too close to the back wall. And where are those giant subwoofers currently located?


If this is referring to me, moving the MLP forward 2-2.5ft isn't an option as I'm already ~8' from the screen and it would also put the surrounds out of whack. I'll add the speaker placement to the main pic.


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## thegeek

Page 33 of the Dolby Atmos Implementation Guidelines says that the side surrounds can be on the sides of the listener from 90 to 110 degrees back from the front of the room. Since you have to have those speakers at that exact position then if you want to hit those numbers then you actually need to move the couch forward anyway.

https://www.dolby.com/us/en/technol...tmos-home-theater-installation-guidelines.pdf

Do consider the screen width though. If it's too much for that close then consider going 2.39:1 instead, you can go wider with a wider aspect ratio since they tend to keep the focus on the middle portion when they shoot that wide.

Sent from my VS996 using Tapatalk


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## Shape of Grey

thegeek said:


> Page 33 of the Dolby Atmos Implementation Guidelines says that the side surrounds can be on the sides of the listener from 90 to 110 degrees back from the front of the room. Since you have to have those speakers at that exact position then if you want to hit those numbers then you actually need to move the couch forward anyway.
> 
> https://www.dolby.com/us/en/technol...tmos-home-theater-installation-guidelines.pdf
> 
> Do consider the screen width though. If it's too much for that close then consider going 2.39:1 instead, you can go wider with a wider aspect ratio since they tend to keep the focus on the middle portion when they shoot that wide.
> 
> Sent from my VS996 using Tapatalk


So I went back and moved the couch forward, it's now 24" off the back wall. In this position, the Ls and Rs are at almost dead on 90deg to the MLP. As for scope, was considering it, just because it would give me more room to do tri-traps in the front corners but my currently projector doesn't have lens memory so I'd have to fiddle with zoom any time aspect ratio changed.


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## thegeek

16:9 is what TV and video games are. All movies are wider than that, and action movies are almost all 2.39:1. It used to be panamorphic lens or bust for constant height screen setups but these days projectors have excellent contrast, more than enough lumens, and motorized lenses with memory isn't an overly rare feature.

If you're building the room for mostly movies, and especially if you'll be using a TV in another room for casual viewing then go scope, make it special.

Sent from my VS996 using Tapatalk


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## Shape of Grey

thegeek said:


> 16:9 is what TV and video games are. All movies are wider than that, and action movies are almost all 2.39:1. It used to be panamorphic lens or bust for constant height screen setups but these days projectors have excellent contrast, more than enough lumens, and motorized lenses with memory isn't an overly rare feature.
> 
> If you're building the room for mostly movies, and especially if you'll be using a TV in another room for casual viewing then go scope, make it special.
> 
> Sent from my VS996 using Tapatalk


The room has been done for few months now. And after watching movies for a few months, I sometimes wish I had gone scope. However, that is getting a bit off topic lol. Right now I wanted to see what treatments can/should be done to the room to improve audio in such a small space.


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## Craig Gordon

Shape of Grey said:


> So I went back and moved the couch forward, it's now 24" off the back wall. In this position, the Ls and Rs are at almost dead on 90deg to the MLP. As for scope, was considering it, just because it would give me more room to do tri-traps in the front corners but my currently projector doesn't have lens memory so I'd have to fiddle with zoom any time aspect ratio changed.


Looking at your drawing, the listeners ears are still behind the side speakers. The listeners ears can be in front of side speakers. I know that psychologically, you may think you want those side speakers further up front but 90 degrees to 110 degrees BEHIND you is proper, and I think it sounds better that way. I also think the surround tweeters should be at ear level or 1 to 2 feet higher. Most importantly, the listener position within the room should be at about 2/3 to 3/4 from the front of the room and away from the back wall to get the best sound. I realize this puts you closer to the screen.

Also, I would put one subwoofer dead center in front, and the other behind your couch, slightly to one side (and the door way makes it so that you have to that anyway), and pointed at the back of the couch.


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## Shape of Grey

What are my better/best options for bass trapping? About the only place I can put a wall to ceiling tri-trap would be back right corner. In the front, I could do a 24" tall only due to the screen being 8 off the walls. There is a 6" air gap between the false wall front and the front wall insulation.....could I stuff that air gap with Roxul and turn the front wall into one big bass trap?

The closet in the back I would guess isn't doing me much favors....should I put the door back on and close it off? or leave the door off (open closet) and put some absorption panels in there/line the walls with pink stuff/Roxul 60, leaving only enough room for the AV equipment?

Lastly as far as reflections go, from what I've read, on SEOS drivers (HTM10s) you don't want to treat first reflections. Is that accurate? How about the rear wall? 4" Roxul panels with 2" air gap (maybe 3 panels along the back wall)?


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## thegeek

The physics of first reflection don't particularly change based upon where speaker the sound is coming out of.

Curious... did you jumper the HTM-10's crossover to enable the HF padding? Your room description didn't mention anything about a baffle wall. The HTMs are designed to be installed in a baffle wall and they're crossover is not baffle corrected. The HF pad jumper is there because without a 1/4 wave wide baffle on the front face (3.5 feet in each direction) then the frequencies coming out of the CD will all be heading towards the listener while half of the lower frequencies will be radiating everywhere. Say something, then place your hands against the sides of your mouth extending straight out to the sides. It changes the frequency response. That's what the HTMs are designed for and without it they'll sound wrong.

Sent from my VS996 using Tapatalk


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## sdurani

Shape of Grey said:


> There is a 6" air gap between the false wall front and the front wall insulation.....could I stuff that air gap with Roxul and turn the front wall into one big bass trap?


Worth a try with either Roxul or pink fluffy. Probably won't attenuate low bass, since that requires a few feet of absorption, but will at least minimize mid-bass above the subwoofer range.


> The closet in the back I would guess isn't doing me much favors....should I put the door back on and close it off?


That will allow you to put an absorption panel on the door and next to it for symmetrical placement.


> Lastly as far as reflections go, from what I've read, on SEOS drivers (HTM10s) you don't want to treat first reflections. Is that accurate?


Side wall reflections are outside the soundstage and aid in spaciousness, so absorbing them comes down to preference. The only place I would absorb on the side walls is the contra-lateral reflections (the left speaker's first reflection on the right side wall and vice versa). This way, sounds from one side of the soundstage aren't heard (however subtly) from the opposite side of the room.


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## Shape of Grey

thegeek said:


> The physics of first reflection don't particularly change based upon where speaker the sound is coming out of.
> 
> Curious... did you jumper the HTM-10's crossover to enable the HF padding? Your room description didn't mention anything about a baffle wall. The HTMs are designed to be installed in a baffle wall and they're crossover is not baffle corrected. The HF pad jumper is there because without a 1/4 wave wide baffle on the front face (3.5 feet in each direction) then the frequencies coming out of the CD will all be heading towards the listener while half of the lower frequencies will be radiating everywhere. Say something, then place your hands against the sides of your mouth extending straight out to the sides. It changes the frequency response. That's what the HTMs are designed for and without it they'll sound wrong.
> 
> Sent from my VS996 using Tapatalk


I installed a single-post switch on each speaker to enable/disable HF padding. I did find an old thread where HF padding came up and mtg90 stated:



mtg90 said:


> The padding just reduces the level of the high frequencies a bit resulting in a more downward tilted HF response and makes the treble more laid back. Could be helpful if you have a highly reflective room or just prefer speakers with a more relaxed sound.


Based on his statement, I left the HF padding in off position as it was behind the AT screen. I may fiddle with it, see how it sounds with it on.


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## Dutch-boy

*Room Layout/Treatment Help Needed*

Good Morning,

This is the only forum I visit that uses "Master Threads". I am certain I have not found the most timely way of searching or navigating them so I generally end up reading pretty much all of it. There are a lot of helpful thoughts/tips/theories explained well here. It has been very useful for me.

I am in the process of upgrading my living room HT. I would like to add some treatment and begin planning for projection down the road (3D capable with fixed screen).
Some of the things I would like to accomplish along the way is replace my wall rack with something lower to get the tv lower for now and allow for larger/lower projection screen in future.
If I went with one of the options in the attached pics (SS2 or SS3)I could also treat the wall behind the unit (on which center channel will sit).
My couch and chairs look nice but are horribly uncomfortable and I also want to replace them with theater/reclining seating. I was thinking just 4/5 individual seats maybe or loveseat/individual combo.
Generally I watch movies alone, but would like to accommodate 4 or 5 viewers occasionally.

Room is 15.5x20.5x8ft or 186x246x96in
Wood flooring over basement.
equipment list is in sig.
FR speakers are 1/6 and 5/6 across front wall and subs are 1/4,3/4. Which I understand to be ideal given room dimensions. MLP on couch is 12ft from front wall (not ideal, I can go back a little further if I have to, but chose this for distance from the screen and the possibility of putting 3601 nearfield right behind)

My treatment thoughts were to start with broadband panels and corner traps in the front wall and a broadband panel on the back wall. 
I have fabric samples coming from GIK and Acoustimac, I have attached spec sheets for what I think may be the most effective products to help me.
I understand for broadband (bass in particular) more/thicker is always better. I am not sure if I can handle the aesthetics of a 7.5 inch panel just yet though. Although the 3601 seemed like a behemoth when it first arrived and after hearing/feeling it...I hardly notice it any more. Incidentally, it is for sale, but I figure I might as well use it until I find a buyer.

My drawings on the pics may be hard to understand so let me try to explain...
From the corners in I was thinking TriTrap and then panel 24x48 horizontal or vertical (because of mains location) then 24x48 horizontal (behind subs, if that makes any sense) and then something to fill in the center behind the rack (and center channel).
This may sound funny given my ideas, but I am not looking for every last single % of improvement...I do want to maintain a certain look. Fortunately for me I think panels used well look "technically cool" and "pro".

Some questions I have regarding the front soundstage are:

How much is gained by putting treatment in the ACTUAL corners of floor/wall as opposed to suspending them just above the 4.5in trim?
Does it do anything to have broadband (bass trap panels) in between the wall and subs?
Do panels allow you to move speakers (front soundstage) closer to the wall? Subs and R L are front port, center is rear.

Are the attached spec sheets apples/apples comparison? The weight and area weight seem to have been calculated differently. 
In the specs for the thickest panels I find weight as:23.5lbs for GIK MBT(7.25 thick) and 28lbs for the DMD BT (6.25 thick)
Has anybody tried both? or able to distinguish which would be best by the specs?

Some additional info.
obviously the front wall provides me with the most leeway treatment wise (amount and thickness). Including wall/ceiling corner.
I just don't know the best solution for equipment placement. I think front/center and down low is most practical given the wiring in place and lay out. All I really plan on having is AVR, Universal disk player and Apple TV.
The furniture along the back wall can be removed or replaced as soon as I can find adequate attractive alternatives. Basically I would just like some sort of cabinet or chest of drawers to store media (primarily 3D blu ray and my fav 2D movies) as well as 3D glasses and black out shades folded up and ARC laptop and mic... I am really having a hard time finding anything though.
Would it be a mistake (overpowering/cancelling front subs) to try to move the 3611 nearfield? I could just lay it on its side and place a cabinet or chest on top. It would practically disappear then lol.

When running ARC how can you tell what can effectively be eq'ed out or corrected vs having to move things (speakers/subs/MLP)?



Regards,


----------



## Mashie Saldana

Dutch-boy said:


> When running ARC how can you tell what can effectively be eq'ed out or corrected vs having to move things (speakers/subs/MLP)?


The general rule for EQ is that it can reduce peaks but it can't boost dips (nulls).


----------



## Dutch-boy

Mashie Saldana said:


> The general rule for EQ is that it can reduce peaks but it can't boost dips (nulls).


Thank you Mashie, I will remember that.


----------



## ereed

Dutch-boy said:


> Good Morning,
> 
> This is the only forum I visit that uses "Master Threads". I am certain I have not found the most timely way of searching or navigating them so I generally end up reading pretty much all of it. There are a lot of helpful thoughts/tips/theories explained well here. It has been very useful for me.
> 
> I am in the process of upgrading my living room HT. I would like to add some treatment and begin planning for projection down the road (3D capable with fixed screen).
> Some of the things I would like to accomplish along the way is replace my wall rack with something lower to get the tv lower for now and allow for larger/lower projection screen in future.
> If I went with one of the options in the attached pics (SS2 or SS3)I could also treat the wall behind the unit (on which center channel will sit).
> My couch and chairs look nice but are horribly uncomfortable and I also want to replace them with theater/reclining seating. I was thinking just 4/5 individual seats maybe or loveseat/individual combo.
> Generally I watch movies alone, but would like to accommodate 4 or 5 viewers occasionally.
> 
> Room is 15.5x20.5x8ft or 186x246x96in
> Wood flooring over basement.
> equipment list is in sig.
> FR speakers are 1/6 and 5/6 across front wall and subs are 1/4,3/4. Which I understand to be ideal given room dimensions. MLP on couch is 12ft from front wall (not ideal, I can go back a little further if I have to, but chose this for distance from the screen and the possibility of putting 3601 nearfield right behind)
> 
> My treatment thoughts were to start with broadband panels and corner traps in the front wall and a broadband panel on the back wall.
> I have fabric samples coming from GIK and Acoustimac, I have attached spec sheets for what I think may be the most effective products to help me.
> I understand for broadband (bass in particular) more/thicker is always better. I am not sure if I can handle the aesthetics of a 7.5 inch panel just yet though. Although the 3601 seemed like a behemoth when it first arrived and after hearing/feeling it...I hardly notice it any more. Incidentally, it is for sale, but I figure I might as well use it until I find a buyer.
> 
> My drawings on the pics may be hard to understand so let me try to explain...
> From the corners in I was thinking TriTrap and then panel 24x48 horizontal or vertical (because of mains location) then 24x48 horizontal (behind subs, if that makes any sense) and then something to fill in the center behind the rack (and center channel).
> This may sound funny given my ideas, but I am not looking for every last single % of improvement...I do want to maintain a certain look. Fortunately for me I think panels used well look "technically cool" and "pro".
> 
> Some questions I have regarding the front soundstage are:
> 
> How much is gained by putting treatment in the ACTUAL corners of floor/wall as opposed to suspending them just above the 4.5in trim?
> Does it do anything to have broadband (bass trap panels) in between the wall and subs?
> Do panels allow you to move speakers (front soundstage) closer to the wall? Subs and R L are front port, center is rear.
> 
> Are the attached spec sheets apples/apples comparison? The weight and area weight seem to have been calculated differently.
> In the specs for the thickest panels I find weight as:23.5lbs for GIK MBT(7.25 thick) and 28lbs for the DMD BT (6.25 thick)
> Has anybody tried both? or able to distinguish which would be best by the specs?
> 
> Some additional info.
> obviously the front wall provides me with the most leeway treatment wise (amount and thickness). Including wall/ceiling corner.
> I just don't know the best solution for equipment placement. I think front/center and down low is most practical given the wiring in place and lay out. All I really plan on having is AVR, Universal disk player and Apple TV.
> The furniture along the back wall can be removed or replaced as soon as I can find adequate attractive alternatives. Basically I would just like some sort of cabinet or chest of drawers to store media (primarily 3D blu ray and my fav 2D movies) as well as 3D glasses and black out shades folded up and ARC laptop and mic... I am really having a hard time finding anything though.
> Would it be a mistake (overpowering/cancelling front subs) to try to move the 3611 nearfield? I could just lay it on its side and place a cabinet or chest on top. It would practically disappear then lol.
> 
> When running ARC how can you tell what can effectively be eq'ed out or corrected vs having to move things (speakers/subs/MLP)?
> 
> 
> 
> Regards,


You seem to have done some research and are on the right track. As far as treatments you want to start with bass traps since bass is always a problem in every room. I would just start with front corners only with either the GIK tri trap or the soffit trap. Soffit traps reach lower frequencies but tri traps saves space and are nicer looking in living room....depends on how much absorption you want. If you do Tri traps you can do full broadband, or get them with diffusion plates on top depending on how reflective your room currently is. So I'd just start with corner bass traps for now and maybe 3rd corner on rear wall if you can move cd rack a little bit. 

About the floor moulding trim, don't worry...just slide the trap up against the trim. It will still work as good or slightly better since you will have about 1 inch more air gap behind and beside it anyway. 

Once you do that you can start working on first reflection points of the room such as side walls and ceilings. Your rear wall are so far behind you that you could do diffusion there or absorption/diffusion combo. Personally I'd do monster trap or Alpha 6A. Thicker is always better since it will absorb lower bass as well which is always welcomed.

So most bank for buck would be front corner bass traps and absorption/diffusion at first reflection points. Then if you want to spend more down the road and get extra improvement seasoned to taste you can work on rear wall and front wall. 

Do you have REW or take measurements? Those would help show how well arc is doing before and after, but you could go by ear as well. REW will really help you find best position for your subs and seating and show you what the mic (your ears) will pick up. Highly recommended!

As far as your seating....you say you can't move it....just follow the rule to never have seating in exact middle of room length (as well as 1/4th, 3/4th) and be between 35-40% of front or rear wall to be out of most room nulls.

I know I answered quick...if I left anything out let me know.


----------



## Dutch-boy

ereed said:


> You seem to have done some research and are on the right track. As far as treatments you want to start with bass traps since bass is always a problem in every room. I would just start with front corners only with either the GIK tri trap or the soffit trap. Soffit traps reach lower frequencies but tri traps saves space and are nicer looking in living room....depends on how much absorption you want. If you do Tri traps you can do full broadband, or get them with diffusion plates on top depending on how reflective your room currently is. So I'd just start with corner bass traps for now and maybe 3rd corner on rear wall if you can move cd rack a little bit.
> 
> About the floor moulding trim, don't worry...just slide the trap up against the trim. It will still work as good or slightly better since you will have about 1 inch more air gap behind and beside it anyway.
> 
> Once you do that you can start working on first reflection points of the room such as side walls and ceilings. Your rear wall are so far behind you that you could do diffusion there or absorption/diffusion combo. Personally I'd do monster trap or Alpha 6A. Thicker is always better since it will absorb lower bass as well which is always welcomed.
> 
> So most bank for buck would be front corner bass traps and absorption/diffusion at first reflection points. Then if you want to spend more down the road and get extra improvement seasoned to taste you can work on rear wall and front wall.
> 
> Do you have REW or take measurements? Those would help show how well arc is doing before and after, but you could go by ear as well. REW will really help you find best position for your subs and seating and show you what the mic (your ears) will pick up. Highly recommended!
> 
> As far as your seating....you say you can't move it....just follow the rule to never have seating in exact middle of room length (as well as 1/4th, 3/4th) and be between 35-40% of front or rear wall to be out of most room nulls.
> 
> I know I answered quick...if I left anything out let me know.


Thanks a bunch ereed,

I Don't have REW but do have ARC (anthem) which has a feature called "quick measure". I'll have to spend some time with it and see if I can get the info needed, if not I suppose I invest in REW.

For the rear wall, what would I use to decide the better option between monster trap or alpha 6a?

The clap test indicates I have echo, so I was figuring that meant I should absorb, but I understand now diffusion can also solve that.

Enjoy your holiday


----------



## ereed

Dutch-boy said:


> Thanks a bunch ereed,
> 
> I Don't have REW but do have ARC (anthem) which has a feature called "quick measure". I'll have to spend some time with it and see if I can get the info needed, if not I suppose I invest in REW.
> 
> For the rear wall, what would I use to decide the better option between monster trap or alpha 6a?
> 
> The clap test indicates I have echo, so I was figuring that meant I should absorb, but I understand now diffusion can also solve that.
> 
> Enjoy your holiday


Please don't confuse ARC with REW since they are 2 different things and do not do the same thing. ARC is just a eq software that actually eqs your peaks/dips. REW is just a measuring software that doesn't make any changes to your system....just shows you the freq response, timing, delay, etc and a bunch of other stuff. Its a software that helps you get most out of your system.

As for the rear wall, both the monster trap and Alpha 6A bass traps are pretty much equal. Alpha 6A is pretty much similar to Monster with scatter plates but Alpha is a better overall panel/diffuser between the two. But if you don't like seeing the plates on top then get the Monster with scatter plates built in. You could do Monster or even 244s on rear wall with Range limiter option (absorbs 400hz and below only and reflects above 400hz) but if you do scatter plate it will diffuse rather than reflect back to the room to make room feel larger.

Far as echo you can fix that by putting down throw rugs as well as panels such as 242s (or 244s which are better to also absorb low end) on the ceiling and side wall reflection points.

I'm also in living room and use GIK soffit traps in 2 corners, 244s with range limiters on rear wall, and a combination of 244 full range and alpha 4a on side walls. In my room the biggest difference was treating the corners and first reflection points. Later on I added more on side wall and ceilings when budget allowed. This is why I say start with corner traps first if you have tight budget since that is where bass "pools/builds up" the most.


----------



## NashvilleMark

I have a bad slap echo in my relatively untreated room (the screen wall is heavily treated, but the side walls aren't). There is not a full back wall, but the opening is covered by a heavy curtain, which I close when watching films. My room has side walls that are 5'8" tall, then a sloped wall up to a flat ceiling 9' high. I'm considering my options, and was thinking of adding columns along the side for decoration and to conceal my side surrounds. Between the columns, I'm thinking of these two options for acoustic treatment:


(1) doing 4x4 and 2x4 panels of OC703 covered in decorative fabric. I'm not a fan of solid colors, so I'm thinking of finding a nice damask or some print which is relatively acoustically transparent.


(2) doing full curtains between columns on the side walls. The draperies that cover the opening to the theater are made of this fabric:
https://www.rosebrand.com/downloads...IFR 20 oz. Crescent 100percent Full Panel.pdf


What would happen if I made curtains of this fabric, or alternatively, made flat panels of it, and put OC703 behind it?


Thanks for your sage advice!


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## Dutch-boy

When you guys look at specs from GIK and Acoustimac panels and corner treatments tested at the same facility and similar manner...Which one seems superior?
It looks to me like the DMD 6" is better over more frequencies.
Does anybody interpret these differently?
Seems as though Acoustimac uses the same panel for corners only bevels the edges.


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## Mocs123

What sort of treatment(s) should I do behind my minimalist screen wall? I'm on a budget but want to do what I can. I think I will need bass traps in the corners - they don't have to look great as you won't be able to see them from the room, does anyone know where to get some on a budget? I see the foam ones on Amazon, but I didn't think lightweight foam would do much for bass.


Any other acoustic treatments I should do behind the screen wall?


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## Mocs123

After doing some more google research (for some reason google finds stuff on AVS that I can't find with the in house search), I am looking to use BIG's method of two layers of 1" Linacoustic with a 3m layer of plastic in between. Now I just have to check with local HVAC shops and Supply Houses to see if I can find it reasonably. 



Can I add more layers in the corner to make bass traps with Linacoustic, or do I need something like OC 703?


Also, I was planning on making four 48"x 24" fabric covered acoustic panels (probably using 703) to go on each wall. If I get a 100' roll of 48" Linacoustic, I will have some left over, could I use it for this use instead of 703? It would save me some money and that's a good thing.


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## ncabw

It sure if this is the right thread to ask this question. 

I have made some panels that are 2’x4’. And in the last couple weeks I’ve moved my seating much closer to the screen. So I was just thinking of just making a cluster of 4 or 6 on each side wall for the first reflection points. Me question is would it be a waste putting them all in same spots. I have a bug you sports jersey that I have to keep in the room so trying to figure out the best layout. 

I have 110” to my first side speaker. If I did 6 in total plus a jersey that would make my over all length 98”. That leaves 10-12” from screen wall to first panel. Does that effect anything. Or I could start right in the corner and then leave 10-12” where the speaker is. 

Also option split the difference on each end. 

Adding pic to try and show what I have. The Mike Tyson is the panel 











Sent from my iPhone using Tapatalk


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## ncabw

So it kind of look like this. Now when I’m watching I can maybe see half of the first 2 panels in my peripheral. It doesn’t bother me at all. 










This is the pic looking straights a head. It didn’t even show up on my phone camera 











Sent from my iPhone using Tapatalk


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## harrisu

I experienced something very interesting yesterday with a change in my HT. I would like to share with you all and then get some ideas of what to do next. 
Room: 12Wx23Lx8H completed sealed dedicated.
treatment: 4" 703 at first reflection of Center on each side wall and also on Ceiling. Front wall, I have 2" 703 behind L/C/R. Don't have any bass traps in corners. Used to have it in corners but in REW didn't really see it much doing.
MLP: 65" away from back wall.


I also had 1 panel (2" 703) on back wall behind on each side behind side seats and also on side wall b/w back wall and MLP. Seems simple room treatment. But since I also wanted to maximize the contrast for my projector, I installed Black Velvet all around the area b/w MLP and the screen. Even the acoustic panels that are covering 1st reflection for center channel are covered with black velvet. 

The change I made yesterday was to replace the back wall acoustic panel with 3d diffuser. Then recalibrated and when I was watching movies, it was muchhhhh better experience. Surround/Surround back sound made me very much feel like I was right in the scene. It very much felt like a sound bubble I was in. So loved the change but at the same time, the front stage didn't produce the same effect. Front stage sounded more distant than back stage. I also read in one of the HT Of The Month thread that Niel suggested the owner not to use too much of Black Velet since it will absorb the High Frequencies anywhere they are installed. This made me thin that the difference I'm hearing b/w surround vs front stage is because of how front stage b/w MLP and screen is all covered with black velvet is absorbing high frequencies. I really like the open surround sound I'm hearing now but not so much how front stage is sounding. 

Do I have to remove this black velvet to get the open sound stage from front as well? I assume I'd also have to install some diffusers b/w MLP and screen?


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## harrisu

sdurani said:


> The only place I would absorb on the side walls is the contra-lateral reflections (the left speaker's first reflection on the right side wall and vice versa). This way, sounds from one side of the soundstage aren't heard (however subtly) from the opposite side of the room.


Very interesting approach. What about Center? We leave center reflection completely open on side wall and only cover contra-lateral reflections for side speakers? Also what would you recommend for ceiling treatment? Please see my post just above explaining what I have in my room. After I got very good sound stage from surround, I'm afraid I'd have to get rid of most of the black Velvet to open up sound stage from front speakers.


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## harrisu

thegeek said:


> The HTMs are designed to be installed in a baffle wall and they're crossover is not baffle corrected.


How do you determine if a speaker needs a baffle wall? I use JBL 4722N and wondering if baffle wall will make it better? In REW, I see that my room has issues in Mids (70-400Hz) and also around the cross-over area (800-1000). I have ~4 feet behind the screen but I use Perf screen so would need atleast 16" b/w speaker and screen. Currently, they are almost touching the back wall so they are like 3 feet away from the screen. The reason I did that was to allow more space b/w Speaker and MLP. These are BIG speakers and produce BIG sound stage but also need good distance to work properly.


----------



## sdurani

harrisu said:


> This made me thin that the difference I'm hearing b/w surround vs front stage is because of how front stage b/w MLP and screen is all covered with black velvet is absorbing high frequencies.


Have you tried turning the treble knob to boost the high frequencies to compensate for them being absorbed by the black velvet?


harrisu said:


> What about Center? We leave center reflection completely open on side wall and only cover contra-lateral reflections for side speakers?


ALL the research I have read concluded that early reflections aid in speech intelligibility, so I don't absorb the side wall first reflections of the Centre speaker. However, it is worth putting absorption on the front wall because those reflections come from the same direction as the L/C/R speakers and can muddy the critical front soundstage. The only other place I would put absorption is the middle of the back wall (directly opposite the Centre speaker).


> Also what would you recommend for ceiling treatment?


Absorption or diffusion, whatever sounds better to you (as long as it reduces the hard reflection).


----------



## harrisu

sdurani said:


> Have you tried turning the treble knob to boost the high frequencies to compensate for them being absorbed by the black velvet?


I use Dirac which uses a curve to determine how the FR needs to look like up to 20K Hz. When I take FR after Dirac is all set and done, I do get up to 18K like 3dB less than 100Hz. That's exactly how the the curve looks like in Dirac and FR in Rew confirms it. Does this mean that Dirac is taking care of high frequencies being absorbed by Black Velvet by boosting them? I can post pre/post FR if that helps? 



> ALL the research I have read concluded that early reflections aid in speech intelligibility, so I don't absorb the side wall first reflections of the Centre speaker. However, it is worth putting absorption on the front wall because those reflections come from the same direction as the L/C/R speakers and can muddy the critical front soundstage. The only other place I would put absorption is the middle of the back wall (directly opposite the Centre speaker).


Ok so you have nothing on side walls to absorb. May be to diffuse to create bigger sound stage? I see many HT of the month and many are designed by Nyel and he uses many diffusers on side/back/celing. He also uses some absorption panels but mostly diffusers.

Absorption or diffusion, whatever sounds better to you (as long as it reduces the hard reflection).[/QUOTE]
Sorry, What's hard reflection?


----------



## sdurani

harrisu said:


> Does this mean that Dirac is taking care of high frequencies being absorbed by Black Velvet by boosting them?


Dunno, I was simply suggesting you do it by ear (increase the treble until it sounds right to you). Nothing more complicated than that.


> What's hard reflection?


A reflection with nothing (diffusion, absorption, furniture, etc) to soften it.


----------



## harrisu

sdurani said:


> Dunno, I was simply suggesting you do it by ear (increase the treble until it sounds right to you). Nothing more complicated than that. A reflection with nothing (diffusion, absorption, furniture, etc) to soften it.


Thx. I don't know if it has to do with more Treble. It has more to do with spaciousness. I can hear the diff b/w surround/surround back VS front stage and that front stage sounds a bit further away from back. But as you and many here at the beginning of thread pointed out that for multi channel front wall should be fully treated. I don't have it fully treated so many be its a good idea to do that. Plus I think I'm going to remove the absorpion panels from side and ceiling walls and then put them on front fall to see how it sounds. 

As I was reading the beginning of this tread, there seemed to be conflicts about how far the diffuser can be placed. Someone said 10 feet and some said it doesn't matter. I placed mine 65" away and seemed to do a good job even though its only 1 24"x24" diffuser on each side of back wall.


----------



## sdurani

harrisu said:


> I don't know if it has to do with more Treble. It has more to do with spaciousness.


You said _"black velvet is absorbing high frequencies"_, so I was suggesting one way of restoring them. If the problem is not longer a lack of high frequencies, then ignore my earlier suggestion (no longer applies).


----------



## harrisu

sdurani said:


> You said _"black velvet is absorbing high frequencies"_, so I was suggesting one way of restoring them. If the problem is not longer a lack of high frequencies, then ignore my earlier suggestion (no longer applies).


Yeah it will be a bit of trial and error kind of approach. I LOVE LOVE LOVE what black velvet does to the image quality. Using JVC RS500 calibrated on a 130" 2.40 screen with 1.3 gain perf really pops the image with black velvet all around. Not as good as OLED but gets very close. Letting go of it will be a sad moment and I"ll have to see how much to compromise to get that sound I'm after.


----------



## HopefulFred

harrisu said:


> I LOVE LOVE LOVE what black velvet does to the image quality. Using JVC RS500 calibrated on a 130" 2.40 screen with 1.3 gain perf really pops the image with black velvet all around. Not as good as OLED but gets very close. Letting go of it will be a sad moment and I"ll have to see how much to compromise to get that sound I'm after.


You could also (temporarily?) Add something in front of the velvet at the reflection points (like a diffuser) and see if that creates the space you're after.


----------



## harrisu

HopefulFred said:


> You could also (temporarily?) Add something in front of the velvet at the reflection points (like a diffuser) and see if that creates the space you're after.


Thumbs up. Will try that. Has anyone here tried anything other than Black Velvet that's AT? The closest stuff I have found is Mellotone from Part Express https://www.parts-express.com/mellotone-premium-black-speaker-grill-cloth-yard-64-wide--260-332?utm_source=google&utm_medium=cpc&utm_campaign=pla&gclid=Cj0KCQjwitPnBRCQARIsAA5n84kmmG86kcG9yMydLWaZZCKmqHvL8hGpInYX9XusQrnw_AKvzgy2dOQaAugMEALw_wcB

I haven't tried it but I'm very sure its not as black as Black Velvet.


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## harrisu

@sdurani , @HopefulFred, I did an experiment yesterday based on what I read on 1st five pages of this thread. The general agreement seemed to be to have a dead front wall in a multi channel room. So I did that. I placed 4" thick 703 Rockwool covering the front wall from year to top. Then b/w MLP, I only had one 1 panel on each side wall and back wall with 1 diffuser on each side L/R. Did the calibration and when I did the listening, it felt dead. All the high frequencies were like gone and room had no spaciousness. Now it could be because I have all the walls b/w MLP and screen covered by black velvet. Then I removed most of the panels from front wall and left only 3 in place (1 in the middle and 1 behind Left and 1 behind Right speaker). This brought back the spaciousness.

But this brings an interesting question. Most likely, the deadness is because of black velvet. So I have 2 options. 

1 - Cover front wall completely and remove the black velvet to the point where it brings spaciousness.
2 - Don't cover the front wall completely and only do to the point where it doesn't take spaciousness away.

In both cases, I would end up with spaciousness but for some reason, option 1 is very much encouraged at least in first 5 pages that I read up to. My question is which one is better and why even when they both provide spaciousness?

Thx.


----------



## HopefulFred

harrisu said:


> ...I removed most of the panels from front wall and left only 3 in place (1 in the middle and 1 behind Left and 1 behind Right speaker). This brought back the spaciousness.
> 
> But this brings an interesting question. Most likely, the deadness is because of black velvet. So I have 2 options.
> 
> 1 - Cover front wall completely and remove the black velvet to the point where it brings spaciousness.
> 2 - Don't cover the front wall completely and only do to the point where it doesn't take spaciousness away.
> 
> In both cases, I would end up with spaciousness but for some reason, option 1 is very much encouraged at least in first 5 pages that I read up to. My question is which one is better and why even when they both provide spaciousness?
> 
> Thx.


We probably need to know what kind of speakers you are using; what's the toe-in status of them; and how far from the walls (front and side) are they. Stereo imaging and and spaciousness are pretty strongly influenced by those factors - because most of the "space" is supposed to be in the recording already. If you are preserving those details in playback, it should there, IMO.

Beyond that, I would say that there may be some ambiguity in what exactly you're hearing and maybe the extra high-frequency reverberance is detracting from other aspects of fidelity when it comes from the screen wall - when you remove most of the screen wall absorption. (obviously I don't know what you're hearing...) I think the best science suggests the it's lateral reflections (first reflection on the same side as the sound source) that are best for widening stereo images - and that's usually what people find most pleasing.


----------



## harrisu

HopefulFred said:


> We probably need to know what kind of speakers you are using; what's the toe-in status of them; and how far from the walls (front and side) are they. Stereo imaging and and spaciousness are pretty strongly influenced by those factors - because most of the "space" is supposed to be in the recording already. If you are preserving those details in playback, it should there, IMO.
> 
> Beyond that, I would say that there may be some ambiguity in what exactly you're hearing and maybe the extra high-frequency reverberance is detracting from other aspects of fidelity when it comes from the screen wall - when you remove most of the screen wall absorption. (obviously I don't know what you're hearing...) I think the best science suggests the it's lateral reflections (first reflection on the same side as the sound source) that are best for widening stereo images - and that's usually what people find most pleasing.


Sure. I am JBL 4722N as L/C/R and JBL SCS-8 as Surr/SurrBack/Atmos. All together its a 7.2.4 system in a completely sealed room. I had to place one sub on the front which moved Right speaker to very close to side wall. So had to toe it in aggressively. Matched Left speaker accordingly. L/C/R are only 4" off the back wall and I have 4" 703 from ear to ceiling. 

I did a little interesting experiment. I was always curious as to how much black velvet absorbs. So I took two of the panel that are covered with black velvet and took out the foam from inside it. Then placed them where I could hear echo when I clapped my hands. After I placed these panels (again no foam inside the panels), and clapped, the echo was gone. This clearly shows that just the black velvet itself was absorbing high frequencies. Clearly having black velvet all around the area B/w MLP and screen was absorbing all the high frequencies. Since I didn't have front wall completely covered, I was still getting some sense of spaciousness because of the sound wave that were moving back and forth (not from side walls). As soon as I covered the front wall, that spaciousness disappeared. So once I realized what black velvet is doing, I took out 2 panels from side walls (have 3 panels on from each side) and 1 from ceiling and tried it out and there it is again. I could hear much better spaciousness when they are removed. Very clear that Black Velvet is absorbing a lot of high frequencies.

So now I have 2 options and need to know the pros and cons
1 - Remove black velvet from side wall and ceiling. 
Pros: More options available like installing diffusers.
Cons: Impacts the video quality since light will reflect off the side/ceiling walls.
2 - Keep black velvet as is and remove the treatments from front wall.
Pros: Great video quality
Cons: I do get spaciousness but need to know if its good enough????? What are the drawbacks of having reflection coming from front wall. Also can't install diffusers on side/celing.


----------



## Mocs123

Crosspost from my build thread as I thought I may get some help here. 



OK. so I feel like I have called every HVAC supply house in the Tri-State area looking for Linacoustic RC and have come up short. It seems like everyone carries the Owens Corning Quieter duct liner and that's what was recommended as a equivalent. I was planning to follow BIG's method of two 1" layers with plastic sheeting in between them behind my screen wall. Has anyone used this product? Looking at the cut sheets, it seems to be very similar, and the OC may have slightly better performance. It comes in the same 1"x48"x100' roll that Linacoustic comes in and I can get a roll for just under $300 out the door. More information attached.


I did some searching and found one or two mentions of this OC duct liner, but nothing definitive on if it is really an alternative.


If I do get a roll I will have some left over. Could I build up the corners to ~6" thick and make effective bass traps? Could I use this instead of OC703 to make acoustic panels? 

What are your thoughts?

Thank you for your help!


----------



## NashvilleMark

Mocs123 said:


> Crosspost from my build thread as I thought I may get some help here.
> 
> 
> 
> OK. so I feel like I have called every HVAC supply house in the  Tri-State area looking for Linacoustic RC and have come up short. It seems like everyone carries the Owens Corning Quieter duct liner and that's what was recommended as a equivalent. I was planning to follow BIG's method of two 1" layers with plastic sheeting in between them behind my screen wall. Has anyone used this product? Looking at the cut sheets, it seems to be very similar, and the OC may have slightly better performance. It comes in the same 1"x48"x100' roll that Linacoustic comes in and I can get a roll for just under $300 out the door. More information attached.
> 
> 
> I did some searching and found one or two mentions of this OC duct liner, but nothing definitive on if it is really an alternative.
> 
> 
> If I do get a roll I will have some left over. Could I build up the corners to ~6" thick and make effective bass traps? Could I use this instead of OC703 to make acoustic panels?
> 
> What are your thoughts?
> 
> Thank you for your help!


Have you tried Insulation Supply Co. in Nashville? www.insulationsupplycompanynashville.com

I went there a couple days ago and bought some Thermafiber panels. They have OC 703 and Thermafiber in a lot of different thicknesses, including 1 1/2 inch, which I hadn't seen anywhere. They have other stuff, too, but I was excited to find these locally.


----------



## artsci2

sdurani said:


> ........ ALL the research I have read concluded that early reflections aid in speech intelligibility, .....


This conclusion is regarding enviornments that are noisy. In noisy enviornmenta, early reflections act like reinforcement to direct sound which improves signal to noise (voice SPL / ambient noise) ratio.

Home theaters are not noisy enviornments so this "early reflections aid in speech intelligibility" conclusion does not apply.

Ref page 8 of
https://www.jblpro.com/pub/technote/spch_intl_1.pdf


----------



## sdurani

artsci2 said:


> Home theaters are not noisy enviornments...


But movie soundtracks are. My comment regarding speech intelligibility was not about having a conversation in a home theatre but hearing dialogue in a movie. The soundtrack is the environment. 

_"Early reflections improve speech intelligibility"_ 
- Floyd Toole, Loudspeakers & Rooms: http://www.wghwoodworking.com/audio/loudspeakers_and_rooms_for_sound_reproduction.pdf 

_"There seems to be consensus in the field that some early reflections actually help make speech more intelligible."_ 
- Mathas Johansson, Dirac white paper: http://diracdocs.com/on_room_correction.pdf


----------



## harrisu

@sdurani+ others, I think I have finally found the solution of my problem with black velvet absorbing high frequencies. I wrote it down in Black out thread here https://www.avsforum.com/forum/24-digital-hi-end-projectors-3-000-usd-msrp/1465053-blacker-theater-better-image-207.html#post58153242

To summarize it: I realized that black velvet was absorbing too much of high frequencies. I still had spaciousness in my room but that was because I didn't have front/back walls treated and sound was bouncing back and forth b/w front and back and provided some spaciousness. After reading up, I realized that front wall should be absorbing everything. I made the change and room became dead . Only way I could make it sound spacious was to remove black velvet but that was taking image quality away. Had to come up with something. 

Solution: I took the panels from side walls and punched holes in it using meat thermometer. It as a sharp tip and gets thicker after that. It was thick enough to punch large enough hole that is not visible to eyes. Then I glued FRK paper with its reflective side facing the room. Did that to 2 panels on each side wall and to one panel on ceiling. Tried it out and it sounded much better. I had to remove one velvet piece completely from ceiling that was closed to MLP in center. After I removed it, the room sounded very spacious. I kinda made black velvet reflective . To some it might not be the perfect solution but based on my listening sessions of 1 hour, I found the sound spacious enough. Plus if I want some more, I can do the same to other panels that are just sitting there empty wrapped in black velvet. This basically allows me to control how much of 1st reflection I want. Please note that I have the front wall treated now with 4" 703 from ear up to ceiling. I can't cover below ear because my speakers are BIG. JBL 4722N with dimention of (49.9 x 30 x 17.75in) http://www.jblpro.com/www/products/cinema-market/screenarray-systems-2-way/4722_4722n#.XPqU8W66Obg. After having 1 Mini marty sitting b/w Center and Right channel, there really isn't much space left.

What do you guys think of my approach. Based on purely how it sounds, well it sounds good so far  Will do more testing later.


----------



## ereed

harrisu said:


> @sdurani+ others, I think I have finally found the solution of my problem with black velvet absorbing high frequencies. I wrote it down in Black out thread here https://www.avsforum.com/forum/24-digital-hi-end-projectors-3-000-usd-msrp/1465053-blacker-theater-better-image-207.html#post58153242
> 
> To summarize it: I realized that black velvet was absorbing too much of high frequencies. I still had spaciousness in my room but that was because I didn't have front/back walls treated and sound was bouncing back and forth b/w front and back and provided some spaciousness. After reading up, I realized that front wall should be absorbing everything. I made the change and room became dead . Only way I could make it sound spacious was to remove black velvet but that was taking image quality away. Had to come up with something.
> 
> Solution: I took the panels from side walls and punched holes in it using meat thermometer. It as a sharp tip and gets thicker after that. It was thick enough to punch large enough hole that is not visible to eyes. Then I glued FRK paper with its reflective side facing the room. Did that to 2 panels on each side wall and to one panel on ceiling. Tried it out and it sounded much better. I had to remove one velvet piece completely from ceiling that was closed to MLP in center. After I removed it, the room sounded very spacious. I kinda made black velvet reflective . To some it might not be the perfect solution but based on my listening sessions of 1 hour, I found the sound spacious enough. Plus if I want some more, I can do the same to other panels that are just sitting there empty wrapped in black velvet. This basically allows me to control how much of 1st reflection I want. Please note that I have the front wall treated now with 4" 703 from ear up to ceiling. I can't cover below ear because my speakers are BIG. JBL 4722N with dimention of (49.9 x 30 x 17.75in) http://www.jblpro.com/www/products/cinema-market/screenarray-systems-2-way/4722_4722n#.XPqU8W66Obg. After having 1 Mini marty sitting b/w Center and Right channel, there really isn't much space left.
> 
> What do you guys think of my approach. Based on purely how it sounds, well it sounds good so far  Will do more testing later.


I know you say you can't treat front wall below ear level. You should def treat it to combat sbir issues though. If room sounds dead just use diffusion so it only absorb low freq while retain high frequencies.


----------



## harrisu

ereed said:


> I know you say you can't treat front wall below ear level. You should def treat it to combat sbir issues though. If room sounds dead just use diffusion so it only absorb low freq while retain high frequencies.


sory how do I def treat? I don't even know what this means . The room was dead because of the usage of black velvet. If I use diffuser, black velvet has to go away which impacts the image quality. I was trying to find a solution that can allow me to leave black velvet in place. I'm sure Diffuser will make the room sound even better if they are placed b/w MLP and screen but that'd require that I remove the black velvets. I do have 2 diffuser on back back each 65" away from MLP on left and right sides of back wall.


----------



## ereed

harrisu said:


> sory how do I def treat? I don't even know what this means . The room was dead because of the usage of black velvet. If I use diffuser, black velvet has to go away which impacts the image quality. I was trying to find a solution that can allow me to leave black velvet in place. I'm sure Diffuser will make the room sound even better if they are placed b/w MLP and screen but that'd require that I remove the black velvets. I do have 2 diffuser on back back each 65" away from MLP on left and right sides of back wall.


Def = Definitely

I was talking about your front wall from ear level to floor behind speakers. While you won't see them due to AT screen and such, it will help bright/live up your room since high end freq will scatter rather than fully absorb. You can also do that on rear wall as well. I was recommending it since your side walls were absorbing all highs so if you bright up some other parts of the walls where you can't see then it will balance itself out. 

As far as diffusion on side walls, you can still use wood slats on top of absorption panels but cover it with GOM black fabric over the whole panel. That pretty much will live up your room. I believe its darker than speaker cloth and shouldn't be noticeable on side walls. 

Or you could add more bass traps with scatter plates or tune membrane to absorb more lows and it will balance it to where highs don't seem overdamped. Different ways to skin the cat.


----------



## artsci2

artsci2 said:


> This conclusion is regarding enviornments that are noisy. In noisy enviornmenta, early reflections act like reinforcement to direct sound which improves signal to noise (voice SPL / ambient noise) ratio.
> 
> Home theaters are not noisy enviornments so this "early reflections aid in speech intelligibility" conclusion does not apply.
> 
> Ref page 8 of
> https://www.jblpro.com/pub/technote/spch_intl_1.pdf





sdurani said:


> But movie soundtracks are. My comment regarding speech intelligibility was not about having a conversation in a home theatre but hearing dialogue in a movie. The soundtrack is the environment.


Early reflections of a noisy sountrack is not going to help because you get early reflections of the noise too. 
The whole point of the "early reflections improve intelligibility" claim is that the signal (speech) is made louder by early reflections which makes it easier to hear above the ambient noise.



sdurani said:


> _"Early reflections improve speech intelligibility"_
> - Floyd Toole, Loudspeakers & Rooms: http://www.wghwoodworking.com/audio/loudspeakers_and_rooms_for_sound_reproduction.pdf


From the same paragraph in your ref: "... the effects on intelligibility are negligible for the most likely lateral reflections (30–60°)..."




sdurani said:


> _"There seems to be consensus in the field that some early reflections actually help make speech more intelligible."_
> - Mathas Johansson, Dirac white paper: http://diracdocs.com/on_room_correction.pdf


Once again, this refers to early reflections of signal. If the noise is in the sound track and it gets reflected too, there's not going to be any improved intelligibility.


----------



## sdurani

artsci2 said:


> From the same paragraph in your ref: "... the effects on intelligibility are negligible for the most likely lateral reflections (30–60°)..."


I was quoting from a bullet point in the conclusions, not the paragraph you were quoting from. From the paragraph after the one you quoted: _"Looking at the overall evidence from these studies it seems clear that, in listening rooms, some individual reflections have a negligible effect on speech intelligibility, and others improve it, with the improvement increasing as the delay is reduced."_ 

These comments are not stated as absolutes. No one said that all reflections from every direction always aid in speech intelligibility all the time. But the research does show that the improvement ranges from negligible to noticeable, rather than detrimental (as most in this hobby believe).


> Once again, this refers to early reflections of signal. If the noise is in the sound track and it gets reflected too, there's not going to be any improved intelligibility.


In a noisy environment, noise gets reflected too, not just speech. Early reflections help the brain sort it out. Note that the quotes about speech intelligibility from 'Loudspeakers & Rooms' and the Dirac room correction paper are in the context of home theatre (or at least home audio playback), not a noisy factory floor or busy classroom.


----------



## ncabw

I'm in the process of making some ceiling sound panels. Can I place them wherever I have space between lights. I'm making a bunch of 2' x 4' panels. Some places I can place 1 and some places I can place 2. Would treating 40-60% of my ceiling make sense?


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## ereed

ncabw said:


> I'm in the process of making some ceiling sound panels. Can I place them wherever I have space between lights. I'm making a bunch of 2' x 4' panels. Some places I can place 1 and some places I can place 2. Would treating 40-60% of my ceiling make sense?


You still need to make sure the panels cover the first reflection points from your seating.


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## ncabw

ereed said:


> You still need to make sure the panels cover the first reflection points from your seating.




Thanks for the reply. I have the first reflection points on the side walls already taken care of. 


Sent from my iPhone using Tapatalk


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## ereed

ncabw said:


> Thanks for the reply. I have the first reflection points on the side walls already taken care of.
> 
> 
> Sent from my iPhone using Tapatalk


I was talking about first reflection points of your ceiling. Side walls are not the only first reflection points.


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## ncabw

ereed said:


> I was talking about first reflection points of your ceiling. Side walls are not the only first reflection points.


Sorry I should of clarified. My plan is to load up as much panels in front of my seating area. Behind the seating I will place them in open areas. I have 3 rows of lights, smoke detector, and 2 rows of Atmos speakers I have to work around. I also have a 30" bulkhead that runs the length of the room on the right side. I guess I could place panels all the way across it?


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## Lindros88

I have heard several recommendations for filling bags with insulation for use as corner bass traps, but I'm wondering what size bags to use. I have some 39 gallon bags. Will those be big enough?


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## asarose247

If you can't find a single bag big enuf for the whole bundle like Roxul, -SnS ,-
use 2 of them from the ends and seal it with duct-tape. . .

just how much real bass trapping - well- it depends


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## asarose247

Floor bounce , ( of bass, mid bass, mids, etc.) between speakers, LCR presumably, and MLP . . .

beyond the recommendation for a thick carpet with rug pad

- under an area carpet, 5 x 7, no rug pad- it's not wall to wall
maybe several , 4 or 5, anti-fatigue mats, in a single layer of course, held together with ducttape at the edges, what ever it takes

this: as today's deal Anti-Fatigue Kitchen Mat
$21.99 $69.99 69% off List , seems more cost effective wrt $/ft^2.

considering it's a good thickness, about 1 1/8th"

what are folks using or have used on the floor, other than thick carpet?

TY


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## asarose247

^ an initial search doens't reveal composition but
may one assume this is a high density foam,?

given the unprecedented thickness


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## sdurani

asarose247 said:


> Floor bounce , ( of bass, mid bass, mids, etc.) between speakers, LCR presumably, and MLP . . .
> 
> beyond the recommendation for a thick carpet with rug pad
> 
> what are folks using or have used on the floor, other than thick carpet?


The Fraunhofer Institute was researching acoustics for their new audio laboratory rooms, wondering whether carpeting was enough or whether additional absorption was needed at the first reflection points on the floor. 2" of absorption was enough to address the floor reflection. Measurements improved but listening tests told another story: 

_"3.1.4. Subjective room assessment: 

Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative – unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this."_ 

Indeed, the one early reflection our human hearing has always heard, even when we're not in a room (i.e., outdoors), is the floor bounce. No surprise things sound "unnatural" when it's not there. 

https://www.iis.fraunhofer.de/conte...indtheNewStudiosandListeningRooms_AES7672.pdf


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## brandon_k_w

I am able to hang an absorption panel on one of my reflection point walls as shown in the solid green arrow, but my other wall is open with a fireplace coming out halfway from the room. Here is a drawing and a photo of what I'm working with, the blue oval is my listening area.

The green dotted line shows how the reflection point for one of the speakers passes behind the fireplace and out of my listening area. Is it still recommended to place an acoustic panel sitting in that open area to absorb that left speakers' sounds, or does this type of design in my house help tone down reflections already by having the sound pass behind the fireplace?


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## HopefulFred

If you were to hang a mirror on the fireplace (or the far left wall) and not see the speaker, the reflection misses you and you don't need to absorb it. 

IMO, the thing to consider in this case is that the right wall reflection is the only one you do hear if you don't totally absorb it, and that will skew stereo imaging and unbalance the soundfield. You've taken the right step to absorb it, but I would encourage to you be as aggressive as possible with your efforts (thick absorption over a wide area).


----------



## brandon_k_w

HopefulFred said:


> I would encourage to you be as aggressive as possible with your efforts (thick absorption over a wide area).


I have six quantity of 2" thick 2'x4' OC703 panels. I might have to modify them into three quantity of 4" thick panels.  I then should be able to fit two panels on the side wall and one on the ceiling. Hoping that will make a big difference.


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## philipbtz

I thought I'd just chime on on some of my experiences with sound treating a room. In a previous house I build dedicated theater which a acoustical professional designed. I had a 7000 liter bass trap with rock wool, all first reflection treated and the whole nine yards..it sounded great but I was not too fond of the rockwool fibers which would get into the air through the fabrics and panels etc. 

In my current home I have another setup. I've treated all my first reflection with mattresses with opened celled foam and on top of that acoustic foam. The floor I have a thick black carpet. As you've probably already figured out I should have some bass problems at this point. But to fix this issue I have three subs in the front and then three subs in the back of the room. On top of this I run Dirac Live. The end results is a very linear bass response with quite even from seat to seat(sweet spot is amazing). So if you don't want to rebuild all the walls in your room and install a giant bass trap this approach does work imo.


----------



## puddy77

I just saw that IKEA now has some small acoustic panel packs: https://www.ikea.com/us/en/catalog/products/00427366/


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## Soulburner

puddy77 said:


> I just saw that IKEA now has some small acoustic panel packs: https://www.ikea.com/us/en/catalog/products/00427366/


Interesting. Someone care to buy a pack and measure absorption coefficients?


----------



## lax01

puddy77 said:


> I just saw that IKEA now has some small acoustic panel packs: https://www.ikea.com/us/en/catalog/products/00427366/


looks like you need A LOT of them to cover a decent size space - how many 15 packs you gonna buy?


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## sdurani

They're half an inch thick. What is that going to absorb?


----------



## Soulburner

sdurani said:


> They're half an inch thick. What is that going to absorb?


Hang one behind the other, about 0.5-1.0" apart.


----------



## flyers10

If my back wall is about almost 16 feet behind the MLP do I need absorption, diffusion or don't need anything? Currently on that back wall is some wavy metal art hanging.


----------



## cyriltra

Hello,

I plan to do some DIY acoustic panels and where I live (not in US), I can find some sound absorbing polyester panels (PET), similar to these ones.

I find them in 9mm (2 density: 1.86kg/m2 and 1.18kg/m2), so i plan to buy enough to stack them by 5 (45mm thick or 1.8in, which will be a density of 9.3kg /m2).
I plan to place them in my living room, so I can't do more than 2in thick (WAF).

Is there any issue if I stack them by layer ? I will probably use some hot glue between layer

(I don't want to use rockwool in my living room because of my young kids)

Thank you


----------



## wookiegr

Does anyone have any air quality concerns with mineral wool and sound insulation in general? I'm building a theater in my basement and have installed mineral wool between all the interior studs and that stuff just rains particles like crazy. I can only imagine what it will shed into the air as the subwoofers are pounding away. I doubt a simple cotton weave will truly save your lungs from inevitable breathing issues over time. Anyone experienced want to chime in on that?


----------



## AndreNewman

wookiegr said:


> Does anyone have any air quality concerns with mineral wool and sound insulation in general?



I bought the Knauf Ecose stuff for my panels, I got some for the loft to try it out and it’s really a good particle free environment now I’ve laid it over the old stuff. It still sheds a little when you cut it but nothing like the regular mineral wool.

I expect it’s what Gik Acoustic and Blue Frog use, well they sell it for diy so I’m pretty sure it’s what they use for their own panels.


----------



## AndreNewman

Hi, looking for some advice with home built panels.

I built one bass trap panel as a test and to work out what I need to install and where. It was 1200mmx600mmx100mm RW45 Knauf Earthwool building slab with a wooden frame, very simple. I decided to take some measurements and try some different locations before cutting the acoustically transparent black velvet I bought to cover them.

My problem is it doesn't seem to do much, I've tried it behind the L&R speakers, across the front corners of the room, rear corners and against the back wall with a bit of a gap. I wasn't expecting a transformation from just one panel but I was expecting a clearer effect than I've seen.

I can't really hear any difference and REW sweeps show only a little less wiggle around 100Hz and 200Hz. I tried propping all the sheets of RW45 I have across one rear corner and then there's a couple of dB difference but I was expecting more.

I am hoping to hear from someone with experience if I should hear & see some effect from one 100mm 4" panel or am I only going to really notice if I have floor to ceiling in all four corners! Am I expecting too much from a moderate amount of room treatment?

The room is ok for first reflection and >300Hz due to thick velvet curtains with heavy liners covering windows and doors on left and right sides of the room. Waterfall seems ok over 300Hz but there's some variations between 100Hz and 300Hz that I was hoping to fix with some home made bass traps.

Under 100Hz is ok, I think, due to three subs and minidsp timing and eq.

I've attached some photos of the panel, in case I'm doing something very wrong and some REW sweeps, these are completely unequalised so as not to affect measurements and a couple of plots showing the Right speaker (no sub) with no panel overlaid with 1 panel behind and with 4 sheets of RW45 across one other corner. I tried to attach the REW files but seems that format is not allowed, I can attach a zip if someone is willing to take a look.

Thanks

Andre


----------



## wookiegr

AndreNewman said:


> Hi, looking for some advice with home built panels.
> 
> I built one bass trap panel as a test and to work out what I need to install and where. It was 1200mmx600mmx100mm RW45 Knauf Earthwool building slab with a wooden frame, very simple. I decided to take some measurements and try some different locations before cutting the acoustically transparent black velvet I bought to cover them.
> 
> My problem is it doesn't seem to do much, I've tried it behind the L&R speakers, across the front corners of the room, rear corners and against the back wall with a bit of a gap. I wasn't expecting a transformation from just one panel but I was expecting a clearer effect than I've seen.
> 
> I can't really hear any difference and REW sweeps show only a little less wiggle around 100Hz and 200Hz. I tried propping all the sheets of RW45 I have across one rear corner and then there's a couple of dB difference but I was expecting more.
> 
> I am hoping to hear from someone with experience if I should hear & see some effect from one 100mm 4" panel or am I only going to really notice if I have floor to ceiling in all four corners! Am I expecting too much from a moderate amount of room treatment?
> 
> The room is ok for first reflection and >300Hz due to thick velvet curtains with heavy liners covering windows and doors on left and right sides of the room. Waterfall seems ok over 300Hz but there's some variations between 100Hz and 300Hz that I was hoping to fix with some home made bass traps.
> 
> Under 100Hz is ok, I think, due to three subs and minidsp timing and eq.
> 
> I've attached some photos of the panel, in case I'm doing something very wrong and some REW sweeps, these are completely unequalised so as not to affect measurements and a couple of plots showing the Right speaker (no sub) with no panel overlaid with 1 panel behind and with 4 sheets of RW45 across one other corner. I tried to attach the REW files but seems that format is not allowed, I can attach a zip if someone is willing to take a look.
> 
> Thanks
> 
> Andre


I think the bass trap has to be a wedge shape in a 45 deg angle to entirely fill the corners, what you have there is an absorption panel meant to be hung on a wall.


----------



## AndreNewman

wookiegr said:


> I think the bass trap has to be a wedge shape in a 45 deg angle to entirely fill the corners, what you have there is an absorption panel meant to be hung on a wall.


I am planning to build some corner traps as well but this was the easiest to try first.

Planning to build something like the Bluefrog BF4040 but 30x30 2.4m height, these initial results are a bit discouraging, I don't want to take over the room for little benefit.

Both Gik (244) and BlueFrog (BF125) sell something exactly the same size as what I built to use as a bass trap on the wall or across a corner so I was hoping for some sort of measurable, audible result. I will admit that their application pictures do have 8 or more panels or traps in them...


----------



## wookiegr

AndreNewman said:


> I am planning to build some corner traps as well but this was the easiest to try first.
> 
> Planning to build something like the Bluefrog BF4040 but 30x30 2.4m height, these initial results are a bit discouraging, I don't want to take over the room for little benefit.
> 
> Both Gik (244) and BlueFrog (BF125) sell something exactly the same size as what I built to use as a bass trap on the wall or across a corner so I was hoping for some sort of measurable, audible result. I will admit that their application pictures do have 8 or more panels or traps in them...


I've been researching bass traps and sound treatments for over a year now as I build my theater room. The traps always end up being wedges. There are tons of youtube videos on how to build bass traps as well as foam traps ready to buy off Amazon. As far are measurable results, someone with more experience will have to address that. The corner chunk from Blurfrog looks like what many have been making and using but at full height of the room and in many cases along the side walls where they meet the ceiling to eliminate as many corners as possible. ...based on my findings online anyways.


----------



## AndreNewman

I've been researching for some time too and finally got chance to start building after moving and getting the other urgent house jobs out of the way.

This is our living room too, so big soffit traps are not really an option, I considered it, mocked something up and we decided it was too much when the curtains are open and the room is used as a lounge. I need to do something around the screen to reduce light reflections so that's a convenient place to do some corner traps with whaley's devore as the ATish fabric.

There's a huge resonance at 32Hz, simulator says it's the front to back wall distance but I've minimised that with two 1/4 room length placed subs, thanks to Dr Floyd Toole's book. I'm experimenting with MSO as well but was hoping to mostly fix the 80 to 200Hz range with moderate room treatments, heavy curtains taking over from 200Hz up.

This weekend I'm going to finish building some smaller corner traps for the wall to floor corner underneath the screen. One of them will also support the center speaker, in all it will be 3.6m of 300mm corner wedge so hoping that is enough to measure and hear a difference...

When I get to the vertical 300x300 traps I understand it's better to cut the rockwool so it's edges are facing out, better absorption?

Am I going in the right direction and need to have patience or do I have unreasonable expectations?

Andre


----------



## Juan Jose Garcia

Hello people!!!
I leave interesting material for the construction of acoustic boxes and speakers.
It is in Spanish, but it is a very complete and interesting page.
Thank you!!
planosbafles.blogspot.com


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## wookiegr

Has anyone ever considered using foam panels and compression fitting them into the wood frame? I am considering a product similar to or exactly this: https://www.acousticalsurfaces.com/flat_faced_melamine_foam.html that I will trim to fit inside the framed art panels. Also, the typical 2" acoustic foam tiles would fit nicely inside my 12"x12" album cover acoustic panels with a little trimming, all without the need of using insulation. For a basic music and gaming room I think these should be decent enough too. The 3" thick piece would fit perfectly in a 3.5" deep wrapped acoustic art panel for a theater room too. Certainly saves on work and hazards of insulation.


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## ereed

Stay away from foam, they don't do anything on lowend.


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## Sittler27

My HT area is at one end of a very large open basement. I've provided pictures from some angles, and can provide more if required.
I'm running a 9.2.2 setup (Paradigm Studio series with in-wall/ceiling surrounds).
Note that my back wall is actually a fair bit back due to open-concept basement - what may look like a blue back wall behind the ping pong table is actually just a drawn curtain, which in another shot I've opened to show the area behind it to the back wall.

I've performed some measurements with an Umik mic + RoomEQ software to position my two SVS NSD-PB12 subs for the best bass response. I've even used same methods to adjust the PEQ slightly on those subs, as well as cross-over points for speakers, etc.

Regardless of all these adjustments, I'm still aware that I'm missing a lot in the sound (mid-tones, richness, sometimes hard to hear dialog on some scenes), and I know a lot of this is due to not really have any acoustic treatments. I haven't treated the room because of the WAF mainly, but I now have "some" agreement I can introduce some acoustic treatments but they are fairly specific:
-I can hang some acoustic absorption panels on the higher part of the ceiling in front of the screen - thinking 3 panels spaced out a big in front of the blue couch
-I can hang some form of acoustic absorption or diffuser panel on the big green wall to the right of the screen behind the other blue couch
-I can hang some form of acoustic absorption panel on the small wall with the LOTR poster opposite the left-most side of the screen
-I do not have agreement on using any bass traps

So, I'm not shooting for a fully treated room here, but want to add just a few acoustic panels that would provide max. benefit.

How would I calculate my acoustic treatments needs, positions, etc. more accurately? How can I tell where to place these panels? How can I tell how big they should be?

For example, I know almost every treated HT room I've seen a picture of has some absorption panels on the ceiling between the main seating and the speakers. Should I just start there and get 3 panels and place them up there knowing that they will undoubtedly improve my sound? What about the big wall - is that a given for a diffuser panel? How big?


----------



## Sittler27

If your back wall is really far behind your main listening position (45' behind), is there any point in trying to treat that wall?

(I also have a floor-to-ceiling room divider curtain hanging in front of that back-wall but still 28' behind the listening position)


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## niterida

Sittler27 said:


> I'm still aware that I'm missing a lot in the sound (mid-tones, richness, sometimes hard to hear dialog on some scenes),


Read this : https://routledgetextbooks.com/textbooks/9781138921368/home-theatre.php


Written by Dr Floyd Toole so you know its good info - goes into what sorts of things cause unintelligibility and how to fix it.


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## niterida

How wide do you need to make a 1st reflection point absorption panel ?


I have drawn up my 1st reflection points and for my 3 seats the points are 573mm (23") apart - so how much wider should I make a panel to cover all 3 points ?
If I made it 800mm wide it would have 3" of absorber material on each side of the outside reflection points - is that enough. 



I would think not, if most panels are made 12" wide for just one reflection means you need 6" either side ?


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## mtbdudex

Sittler27 said:


> If your back wall is really far behind your main listening position (45' behind), is there any point in trying to treat that wall?
> 
> 
> 
> (I also have a floor-to-ceiling room divider curtain hanging in front of that back-wall but still 28' behind the listening position)




Your talking 45 feet?? Not 45 inches?.... 
if so that’s not small room acoustics anymore 


Sent from my iPhone using Tapatalk


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## Sittler27

mtbdudex said:


> Sittler27 said:
> 
> 
> 
> If your back wall is really far behind your main listening position (45' behind), is there any point in trying to treat that wall?
> 
> 
> 
> (I also have a floor-to-ceiling room divider curtain hanging in front of that back-wall but still 28' behind the listening position)
> 
> 
> 
> 
> 
> Your talking 45 feet?? Not 45 inches?....
> if so thatâ€™️s not small room acoustics anymore
> 
> 
> Sent from my iPhone using Tapatalk
Click to expand...

Sure, ok not small room. So do I need to treat that back wall?


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## sdurani

Sittler27 said:


> So do I need to treat that back wall?


Probably not with those curtains in place.


----------



## no_cure

niterida said:


> How wide do you need to make a 1st reflection point absorption panel ?
> I have drawn up my 1st reflection points and for my 3 seats the points are 573mm (23") apart - so how much wider should I make a panel to cover all 3 points ?
> If I made it 800mm wide it would have 3" of absorber material on each side of the outside reflection points - is that enough.
> I would think not, if most panels are made 12" wide for just one reflection means you need 6" either side ?


So, presumably you used the mirror technique to mark where your reflection points are? Ideally, you’ll end up having 3 1st reflection points per seating position (L/C/R),which in your case would total to 9 reflection points on each L and R walls. 

Not sure if there is a formula, but in my case, I attempted to cover each reflection point to be at least as wide (and tall) as my actual speaker baffles (not the cabinet), but that didn’t always work out. So, it turned out in my case that 1 panel covered 2 reflection points with a couple of inche to spare to the sides...

Dimensions of my panels are 24.25” x 48.25”


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## niterida

no_cure said:


> So, presumably you used the mirror technique to mark where your reflection points are? Ideally, you’ll end up having 3 1st reflection points per seating position (L/C/R),which in your case would total to 9 reflection points on each L and R walls.
> 
> Not sure if there is a formula, but in my case, I attempted to cover each reflection point to be at least as wide (and tall) as my actual speaker baffles (not the cabinet), but that didn’t always work out. So, it turned out in my case that 1 panel covered 2 reflection points with a couple of inche to spare to the sides...
> 
> Dimensions of my panels are 24.25” x 48.25”



I have done further research and there is no formula - just "wider" seems to be the consensus


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## AndreNewman

They need to be wide enough such that if you move about, sit in a slightly different spot you are still covering the reflection spots.

Also sound waves are large, not small like the light bouncing off the mirror so wider the panels are the more effective they will be. I built some small panels recently and they didn’t seem to do much, it wasn’t until I built bigger and more panels that I started to hear a difference.


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## ncabw

I made some panels in the past with safe n sound insulation. I had some sports picture printed on what the printing shop called acoustical material. However I don’t think it’s the greatest. If blow on it I really don’t feel any air. I have pick up some burlap for ceiling panels I did. I have some left over and was thinking of making new side panels to go in between the ones I currently have. 

This should be my first reflection point? so I will have 2’ original panel. Then a new 4’ burlap followed be another 2’

My question is. Does material really matter. If I could do all sport theme I think i would rather that. Or should is it still best to just do the burlap? 

Also my back wall is about 12’ behind me. Do I need to add any panels their??












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## no_cure

ncabw said:


> My question is. Does material really matter. If I could do all sport theme I think i would rather that. Or should is it still best to just do the burlap?


The absorption material itself + the fabric covering the panel DO MAKE a significant difference, so choose wisely.



ncabw said:


> Also my back wall is about 12’ behind me. Do I need to add any panels their??


We need more information, primarily your room dimensions and layout. Absorption panels for back wall is always recommended and beneficial, especially if you’re closer to the back wall than the front wall (where your speakers are situated). Generally speaking, the smaller the listening room is, the more advisable it is to acoustically treat your room as, in such scenarios, room modes, flutter echo, reverberations, reflections, dips and peaks and serious bass issues are more ubiquitous. 

Regardless, for the biggest ROI and acoustical improvements, as starting point, I would advise to:

1.	to place your MLP (main listening position) at ~ 38% of the length of room from the front wall (if not feasible, back wall might work too). 
2.	use the mirror technique to identify the 1st (aka early) reflection points from the MLP & place absorption panels on both R and L walls plus the ceiling. If you DON’T have carpeted floor, always place a rug or similar (the thicker the better). 
3.	install bass traps in the corners 
4.	NEVER sit right in the middle of the room – worst possible scenario due to dips/peaks from room modes
5.	NEVER place the MLP right against the back wall

FYI, the best acoustically sounding rooms tend to employ BOTH absorption + diffusion panels. 

Hope this helps.


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## no_cure

ncabw said:


> This should be my first reflection point? so I will have 2’ original panel. Then a new 4’ burlap followed be another 2’


Probably you already know this, but just in case my previous post isn't clear enough...always place your absorption panels at 1st reflection points which are found by the mirror technique. Not sure about your room dimensions, but the panel with the Maple Leaf hockey player seems waay too close to the screen, so I wouldn't think it would do anything. 

Good reading material: https://www.gikacoustics.com/early-reflection-points/


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## flyers10

These are where 1st reflections are on my ceiling for L, C & R. I've seen many room pics of just 2 panels used on the ceiling 1st reflections and covering the L & R only. Do I need to put a panel in the middle for the center?


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## no_cure

flyers10 said:


> These are where 1st reflections are on my ceiling for L, C & R. I've seen many room pics of just 2 panels used on the ceiling 1st reflections and covering the L & R only. Do I need to put a panel in the middle for the center?


I wouldn't go by that as each HT/2ch listening room is unique. In some pictures that I've seen, 1 panel actually covered two 1st reflection points (L and C)...so it really depends on how wide/long your panels are vs. distance between the 1st RP.

In your particular case, looks like your setup is geared towards HT (could be wrong...) so yes, I WOULD ensure that the 1st reflection point for the center channel is covered; that will provide the best legibility for dialog since it makes up ~80% of most movies.


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## ncabw

no_cure said:


> Probably you already know this, but just in case my previous post isn't clear enough...always place your absorption panels at 1st reflection points which are found by the mirror technique. Not sure about your room dimensions, but the panel with the Maple Leaf hockey player seems waay too close to the screen, so I wouldn't think it would do anything.
> 
> 
> 
> Good reading material: https://www.gikacoustics.com/early-reflection-points/




Thanks for the reply’s. 

I had the hockey player panel originally at the 1st reflection point. I moved it forward and the Jordan picture further back. Leaving my 1st reflection point open. This is where I will build the new panel. Sounds like its best to use the burlap material then. Also I moved the first panel up because I didn’t want to throw it away since I like them and I made 4 of them. 

From your previous reply 

-I have 2 corner base traps on the back wall corners 
- I have 5 ceiling panels 
- my rooms 22’ long and I’m siting around the 9-6” form the front wall. 

As for diffusers I would like to make some but I haven’t found a good site in how to do it. 

Her are some pics form when I was building the ceiling panels and corner bass trap. 




















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## no_cure

flyers10 said:


> These are where 1st reflections are on my ceiling for L, C & R. I've seen many room pics of just 2 panels used on the ceiling 1st reflections and covering the L & R only. Do I need to put a panel in the middle for the center?


Looking at your setup again, I have a somewhat similar setup where my room isn't symmetric. Your L side seems to lead to an open area, so probably you're good there, but are you able to treat the R wall where the windows are? I would venture to say that leaving that wall untreated would be worse than installing absorption panels on the ceiling. Distance wise, since your speakers look to be floor monitors, the ceiling is farther away from the speakers than the R wall and floor are...so I would treat the surfaces that are closer first.


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## sdurani

FYI, 38% room length is the location of one of the nulls of the 4th order length mode. Modal nulls are always at even divisions (half, quarters, sixths) of room length, so it is better to place the listeners' ears at one of the odd divisions (thirds, fifths) of room length. For example, 1/3rd room length is close to 38% but avoids the null. For 2 rows, 3/5th and 4/5th room length are good starting points.


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## flyers10

no_cure said:


> flyers10 said:
> 
> 
> 
> These are where 1st reflections are on my ceiling for L, C & R. I've seen many room pics of just 2 panels used on the ceiling 1st reflections and covering the L & R only. Do I need to put a panel in the middle for the center?
> 
> 
> 
> Looking at your setup again, I have a somewhat similar setup where my room isn't symmetric. Your L side seems to lead to an open area, so probably you're good there, but are you able to treat the R wall where the windows are? I would venture to say that leaving that wall untreated would be worse than installing absorption panels on the ceiling. Distance wise, since your speakers look to be floor monitors, the ceiling is farther away from the speakers than the R wall and floor are...so I would treat the surfaces that are closer first.
Click to expand...

Thanks for responses. Yes the left side is wide open to the kitchen. I have two 24"x48" panels that I'll be putting horizontally on the right wall right under the windows. I can't have them be higher and block any of the shutters/windows due to WAF. 
I was also contemplating using a panel behind each tower and possibly the center. What's your thoughts on front wall treatment?


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## no_cure

flyers10 said:


> Thanks for responses. Yes the left side is wide open to the kitchen. I have two 24"x48" panels that I'll be putting horizontally on the right wall right under the windows. I can't have them be higher and block any of the shutters/windows due to WAF.
> I was also contemplating using a panel behind each tower and possibly the center. What's your thoughts on front wall treatment?


I find, all things considered, one of the most cost effective ways to acoustically treat windows present in HT setups is to install heavy curtains/window drapes over them. Following the 'form follows function' adagio, this is obviously not the preferred route, especially in a family room, but it's so much better than having glass or sheet-rock reflecting sound waves. If the 1st reflection points land somewhere in between the windows, you can have some art panels done and still have the WAF. 

Absorption panels behind front wall speakers address SBIR, aka Speaker Boundary Interference Response. That's a bit different than treating 1st reflection points. 

I recommend reading this article on taming SBIR issues: http://www.gikacoustics.com/speaker-boundary-interference-response-sbir/

With that said, my priority list as follows:

1. L and R walls: installed 2 x (24.25"x 48.25") on each wall absorption panels @ a thickness of 5.25" 
2. back wall: 2 x (24.25″ x 48.5″) with a thickness of 7.5"
3. All 4 corners (floor to wall): 4 x (24" x 48") triangle shaped

I never got around to installing 1 x (24.25"x 48.25") on the ceiling, but I will to primarily treat the C channel; maybe I get lucky and get all 3 L/C/R covered with 1 just panel (my ceiling is pointy given slope of roof). However, with just the above, both my 2-ch critical music listening and my HT movies have DRAMATICALLY improved. I'm talking like NIGHT vs. DAY here, I got myself asking..."what the heck, why did I wait this this long?"


----------



## no_cure

ncabw said:


> - I have 2 corner base traps on the back wall corners
> - I have 5 ceiling panels
> - my rooms 22’ long and I’m siting around the 9-6” form the front wall.


Some feedback:

a. Would it be feasible to install corner base traps along the front wall as well? Read this http://arqen.com/bass-traps-101/placement-guide/
b. 5 ceiling panels...why so many? How many ceiling 1st reflection points are you treating with 5 panels?
c. Can you move the MLP slightly forward (towards the screen), say by 1 foot or so? I would target to sit around 8.3' to 8.5' from front wall given your room's length


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## ncabw

no_cure said:


> Some feedback:
> 
> 
> 
> a. Would it be feasible to install corner base traps along the front wall as well? Read this http://arqen.com/bass-traps-101/placement-guide/
> 
> b. 5 ceiling panels...why so many? How many ceiling 1st reflection points are you treating with 5 panels?
> 
> c. Can you move the MLP slightly forward (towards the screen), say by 1 foot or so? I would target to sit around 8.3' to 8.5' from front wall given your room's length




A) I have about 14” from screen to side wall. My plan was to make a corner trap around 11-12 x 24” a rectangle shape

B)I added that many because my room has nothing in it for absorbing sound so I figured more is better. I will post a pic because behind my seating positions my walls are covered in Jerseys. So I thought the ceiling would be a good option. 

C) my screen is 160” and I tried to sit at the 9’ mark and it was a bit to close. 9’ 6” is the closet I can sit where I feel the best. 

Here are some Audyssey graphs if this means anything.

















Sent from my iPhone using Tapatalk


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## brettus

Have you measured the room with a microphone and REW (lots) before doing all this work or you've just gone ahead on advice from here? I ask as tbh majority of people are happy before diving in the rabbit hole but if you're going to do it then you might as well do it properly and measure accurately. Not taking anything away from Audyssey but it's like any auto system and prone to drift...

With those pictures you printed I'd be putting a couple of inches of your prefered insulation behind them and chuck them up on the walls as they are yours and you obviously love them...there's no point in being drab for the sake of half a dB!


----------



## ncabw

brettus said:


> Have you measured the room with a microphone and REW (lots) before doing all this work or you've just gone ahead on advice from here? I ask as tbh majority of people are happy before diving in the rabbit hole but if you're going to do it then you might as well do it properly and measure accurately. Not taking anything away from Audyssey but it's like any auto system and prone to drift...
> 
> With those pictures you printed I'd be putting a couple of inches of your prefered insulation behind them and chuck them up on the walls as they are yours and you obviously love them...there's no point in being drab for the sake of half a dB!




I bought a mic and downloaded rew software and a PDF book on how to use it. I just haven’t had the time to learn how to use it. 

Right now those pictures are framed with 1X6 and have 1 layer of safe n sound in them. So about 3inches thick With 2-1/2 air gap behind. Are you saying add more insulation and make them act like a corner bass trap??? Then maybe stack two pictures right on top of each other to give me my full 9’ to ceiling? 


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## pau

Im buying GIK panels with tri traps for room threatment. 

Closest surface of reflections to listening position is the rearwall. Would it be better to fill rearwall with those half circle shaped polyfusor panels or new impression panels? Or mayby mix both or just go full absorption?


----------



## no_cure

pau said:


> Im buying GIK panels with tri traps for room threatment.
> 
> Closest surface of reflections to listening position is the rearwall. Would it be better to fill rearwall with those half circle shaped polyfusor panels or new impression panels? Or mayby mix both or just go full absorption?


Are you saying that you don't have L and R walls anywhere nearby your front stage? If so, you're in an envious position my friend...

Anywho, I recently bought GIK acoustic panels myself - and I absolutely swear by them!! My recommendation, upon numerous emails and phone calls with the friendly technical folks @ GIK is:

- side walls + ceiling: GIK 244 panels 
- rear wall: GIK monster traps
- the bottom trihedral corners (floor-wall-wall): GIK tri-traps

That's what I've done and I am now a true believer that acoustical panels work magic! I could have saved myself the price of a new car by not upgrading my gear (amps, speakers, pre/pros) if I would have installed them much much sooner...

In the future, my upgrade path would be to place:

1. 242s behind L and R speakers to tame SBIR
2. diffusion panels immediately adjacent to L and R speakers and to MLP (to create 'spaciousness' and increase the imagery of my room)


----------



## pau

no_cure said:


> Are you saying that you don't have L and R walls anywhere nearby your front stage? If so, you're in an envious position my friend...
> 
> 
> 
> Anywho, I recently bought GIK acoustic panels myself - and I absolutely swear by them!! My recommendation, upon numerous emails and phone calls with the friendly technical folks @ GIK is:
> 
> 
> 
> - side walls + ceiling: GIK 244 panels
> 
> - rear wall: GIK monster traps
> 
> - the bottom trihedral corners (floor-wall-wall): GIK tri-traps
> 
> 
> 
> That's what I've done and I am now a true believer that acoustical panels work magic! I could have saved myself the price of a new car by not upgrading my gear (amps, speakers, pre/pros) if I would have installed them much much sooner...
> 
> 
> 
> In the future, my upgrade path would be to place:
> 
> 
> 
> 1. 242s behind L and R speakers to tame SBIR
> 
> 2. diffusion panels immediately adjacent to L and R speakers and to MLP (to create 'spaciousness' and increase the imagery of my room)


I read on theyr web page that those polyfusers are adviced if rear wall is close. But the impression could add nice touch to interior, so mayby i mix them. 
Could allso do 244's tought desision. 

2 stacked tri traps is what can be done with closets and doors on other corners. 


My L wall is like 20feet as the room opens to kitchen. R wall is 8 feet apart to balcony and windows.. 

Sofa is closer to backwall


----------



## sdurani

pau said:


> Closest surface of reflections to listening position is the rearwall. Would it be better to fill rearwall with those half circle shaped polyfusor panels or new impression panels? Or mayby mix both or just go full absorption?


I would go with broadband (4"-6" thick) absorption directly behind the listeners. Dialogue and other sounds from the front soundstage should not be heard (however subtly) coming from behind you.


pau said:


> My L wall is like 20feet as the room opens to kitchen. R wall is 8 feet apart to balcony and windows..


That's going to result in an asymmetrical soundstage. I would cover the right wall with thick pleated drapes to mimic the lack of wall on the left side and restore symmetry.


> That why i thought to focus behind the most.


Front wall is more important, since you want to minimize reflections from surround speakers that will muddy the critical front soundstage. Good places for broadband absorption would be between your front speakers, which will also tame boundary cancellation dips caused by your L/R speakers and front wall reflections.


----------



## brettus

ncabw said:


> Right now those pictures are framed with 1X6 and have 1 layer of safe n sound in them. So about 3inches thick With 2-1/2 air gap behind. Are you saying add more insulation and make them act like a corner bass trap??? Then maybe stack two pictures right on top of each other to give me my full 9’ to ceiling?
> 
> 
> Sent from my iPhone using Tapatalk


No I would leave them how they are, perfectly fine.
I'm not knocking the technique here as I did this myself in my cave but for a lot of people I would just say make some nice diy panels, stick them at critical reflection points and be happy to show them off to your friends or and be done with it...especially with some of the quality home theatre rooms and listening rooms that I've seen on here!


----------



## xpl0sive

Hi Guys,

Hoping someone can help. I'm wanting to add some acoustic treatment to my room, but it's a fairly small room and I want to maintain the aesthetics of the room. How would I go about adding some panels in this room while keeping it symmetrical and looking good?


----------



## PretzelFisch

pau said:


> Im buying GIK panels with tri traps for room threatment.
> 
> Closest surface of reflections to listening position is the rearwall. Would it be better to fill rearwall with those half circle shaped polyfusor panels or new impression panels? Or mayby mix both or just go full absorption?


You can email them and get a room consult for very cheap to free. Talking to them was a lot of help for my room.


----------



## pau

PretzelFisch said:


> You can email them and get a room consult for very cheap to free. Talking to them was a lot of help for my room.


I'll contact them and see suggestions, but it has to be mix of design/aesthetics and acoustics as the place is not dedicated to HT only.

Thanks for tips.


----------



## Sam Ash

Any decent room acoustics simulation software that is easy to use and provides a good basic idea of how sound behaves in a room across the full range based on sound sources in the room. something geared towards aiding treatment ?

Odeon seems to be comprehensive, has anyone here used it ?


----------



## woodboss83

Getting ready to build acoustic panels for the HT. Wondering if it is acceptable to use linacoustic in the panels or the pink fluffy stuff? I have some of both left over from my build. Thanks!

Nick


----------



## SierraMikeBravo

Sure you can use pink fluffy stuff, but it won't give you a lot of traction except in the high frequencies. Consider using 3 or 6 lb/cu^3 ductboard. That'll work a bit better on the frequencies you are likely trying to target.


----------



## Da1las

I was looking at this place and plan to use the home theater panels where it splits up an underwater coral reef picture into 3 panels on each side of the front of the room.

https://www.acoustimac.com/hometheater



xpl0sive said:


> Hi Guys,
> 
> Hoping someone can help. I'm wanting to add some acoustic treatment to my room, but it's a fairly small room and I want to maintain the aesthetics of the room. How would I go about adding some panels in this room while keeping it symmetrical and looking good?


----------



## wpbpete

Do you guys run room correction again _*after*_ treatment? I just did and it cleaned things up quite a bit.


----------



## AndreNewman

wpbpete said:


> Do you guys run room correction again _*after*_ treatment? I just did and it cleaned things up quite a bit.




Most definitely.

Hopefully after the treatments it has a lot less to correct. If you are still running with the correction from before you added the room treatment then it’s probably making things worse.

I’m part way through my room treatments but already I see a big difference in the auto correction my avr does. The difference is such that I expect I won’t use the auto correction again, some small manual adjustments (referring to rew sweeps) sound much better than the “magic” auto correction, ypao for reference so not the best system, dirac might still be worthwhile I don’t know.


----------



## wpbpete

AndreNewman said:


> Most definitely.
> 
> Hopefully after the treatments it has a lot less to correct. If you are still running with the correction from before you added the room treatment then it’s probably making things worse.
> 
> I’m part way through my room treatments but already I see a big difference in the auto correction my avr does. The difference is such that I expect I won’t use the auto correction again, some small manual adjustments (referring to rew sweeps) sound much better than the “magic” auto correction, ypao for reference so not the best system, dirac might still be worthwhile I don’t know.


Glad I asked, thx. I was thinking that adding treatments to the current room correction is a manual tweak to it and there would be no need to run it again afterward. My surrounds sounded convoluted and I couldn't distinguish where sound was coming from, so I decided to re-run it and Voila! I'm happy now


----------



## knappster007

I've seen a few posts in this thread over acoustical treatment placement. I'm linking another thread I started that describes a tool I developed to calculate treatment placement locations along with the acoustic impact of speaker placement.

Wanted to share if anyone was interested. Here is the link to the tool (it was developed in Excel but delivered through a web site so you don't need excel and it also works on cell phone web browsers). 

Link: Link Here

Previous thread: https://www.avsforum.com/forum/19-dedicated-theater-design-construction/3069262-room-layout-analysis-spreadsheet.html


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## AndreNewman

wpbpete said:


> Glad I asked, thx. I was thinking that adding treatments to the current room correction is a manual tweak to it and there would be no need to run it again afterward. My surrounds sounded convoluted and I couldn't distinguish where sound was coming from, so I decided to re-run it and Voila! I'm happy now




I had a similar experience, then realised I hadn’t redone the auto setup.

Tells a lot about the weird stuff that auto room correction does!


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## 3fingerbrown

Hey guys I’m looking for a cost effective way to treat echo noise in an indoor sport court. So far this seems like the most cost effective choice that I’ve seen:

https://www.acousticalsurfaces.com/echo_eliminator/wall_panel.htm

I would be treating an area on the ceiling first, it’s maybe 16’x22’ in size, but maybe some other places too. The beauty of this system is there are no frames to mess with, just glue and install, and it looks like you could cut it to fit pretty easily. One of my concerns is that it could sag over time if it is mounted on a ceiling, but the website shows it mounted in many ceiling applications.

What do you think?


----------



## AllexxisF1

Hey Everyone, 

I have been drowning myself into information on acoustical treatments in the last few weeks. From Youtube to scientific white papers to online forums. I even had the wonderful experience of speaking with Dennis Foley last Friday on his approach for my new home theater. The solution sounds solid enough, the cost, however, is well out-of-reach for me (4x 10-inch carbon bass traps (front), 6x acoustic foam panels (3x on each side wall). 

So, I'm tempted to tackle this with DIY panels and Owens Corning 703 or similar materials. The first stage will just be absorption on the front stage and side reflection points. I tossed in a photograph of the front stage with black boxes representing panels in black. Just curious if you seasoned folks find something wrong with this preliminary placement. Any advice would be appreciated.


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## wookiegr

Nice to see a screen larger than the speakers in a "home theater" environment. Kind of rare these days.


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## QuyZilla

I'm looking at adding some acoustic panels to the ceiling. Pretty hard to hold a mirror that high to find the FRP. Is it a rule that the FRP for the ceiling is half the distance between speaker to the MLP?


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## HopefulFred

QuyZilla said:


> Is it a rule that the FRP for the ceiling is half the distance between speaker to the MLP?


This is close to true. It is true IF the speaker and listener are the same height relative to the ceiling (which SHOULD be true) and if the ceiling is horizontal.


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## Tom J. Davis

Anybody treated a bonus room like this? Having a hard time finding info on how or if its even worthwhile to try and treat this room. The room is gutted and awaiting the spray foam insulation guy to do his thing so I can do whatever I want with it. 



24x14x8 with 55" knee walls. Ceiling is 7ft wide. 



Thanks for any and all responses!


----------



## Swoosh830

I'm trying to decide between GIK corner Tri Traps and the Soffit traps for the front corners of my room. I already have a Tri Trap in each of the rear corners of the room as denoted by the attached floor plan. The front of the room is somewhat of a nook, so only one corner is a 'true corner' of the room. My front sound stage extends beyond the width of this nook with the L speaker being placed partially in front of the COATS closet. The R speaker is against the wall in front of the window.

I do have the ability to take measurements with REW. Is there any way of using this to determine which type of bass trap would work best in the front of my room, whether it's moving the mic near the corners or somewhere else in the room? I've also attached two recent measurements taken with ONLY the subwoofers and no room treatments or EQ. The blue line is the most recent after tweaking the placement of each sub. Since I was able to get within 10 dB with no treatments or EQ, would Tri Traps suffice in the front corners of the room? It's hard for me to justify the cost of the Soffit traps. Some say to add as many bass traps as can fit, while others say it's not always necessary. I've even heard Gene from Audioholics claim that there can be too much trapping and too much can require the levels of the subs to be raised (I'm paraphrasing, but it's from a recent video he did with measuring multiple subs with REW).

Thanks in advance for any advice.


----------



## CAMovieBuff

Apologies if this has already been answered or if I'm asking in the wrong thread, but I have a question about music and movies that are good for testing the acoustics of a room. I have a hardwood floor that I plan to cover (with what I haven't figured out), and it would be great to have some kind of before and after experience. Do you have a favorite piece of music or scene from a movie that you use to check out a room? Thanks!


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## harrisu

knappster007 said:


> I've seen a few posts in this thread over acoustical treatment placement. I'm linking another thread I started that describes a tool I developed to calculate treatment placement locations along with the acoustic impact of speaker placement.
> 
> Wanted to share if anyone was interested. Here is the link to the tool (it was developed in Excel but delivered through a web site so you don't need excel and it also works on cell phone web browsers).
> 
> Link: Link Here
> 
> Previous thread: https://www.avsforum.com/forum/19-dedicated-theater-design-construction/3069262-room-layout-analysis-spreadsheet.html


Just looking into the link. Cool Stuff. One issue I found though is that it tells you where to put the speakers without asking the width of it. For example, in my case, its telling me that I should put Left speaker 3'2 from side walls (12' wide room). My L/C?r speakers are JBL 4722N and each is 30" wide. So them together is 90". Room is 12' which means 144" wide. With that, I have them 16" away from center speaker which ends up leaving 9" from side wall. There is no way I can have them 3'2" (38") away from side wall since its not even physically possible. What I'm trying to point out is that the calculation is missing speakers Width. 

Would be great if it could allow user to enter the speaker dimensions and then it can tell what's the optimum distance it should have.
Another great feature would be if we can input the location of speakers and it can highlight the issues with one would have.


----------



## Soulburner

knappster007 said:


> I've seen a few posts in this thread over acoustical treatment placement. I'm linking another thread I started that describes a tool I developed to calculate treatment placement locations along with the acoustic impact of speaker placement.
> 
> Wanted to share if anyone was interested. Here is the link to the tool (it was developed in Excel but delivered through a web site so you don't need excel and it also works on cell phone web browsers).
> 
> Link: Link Here
> 
> Previous thread: https://www.avsforum.com/forum/19-dedicated-theater-design-construction/3069262-room-layout-analysis-spreadsheet.html


There is research showing that lateral reflections are very important and often preferred over their absence, and how vertical and lateral reflections differ in their effects on our perception due to the shape of our ears. Does your spreadsheet take this into account?

Otherwise, very cool.


----------



## knappster007

harrisu said:


> Just looking into the link. Cool Stuff. One issue I found though is that it tells you where to put the speakers without asking the width of it. For example, in my case, its telling me that I should put Left speaker 3'2 from side walls (12' wide room). My L/C?r speakers are JBL 4722N and each is 30" wide. So them together is 90". Room is 12' which means 144" wide. With that, I have them 16" away from center speaker which ends up leaving 9" from side wall. There is no way I can have them 3'2" (38") away from side wall since its not even physically possible. What I'm trying to point out is that the calculation is missing speakers Width.
> 
> Would be great if it could allow user to enter the speaker dimensions and then it can tell what's the optimum distance it should have.
> Another great feature would be if we can input the location of speakers and it can highlight the issues with one would have.


I've made the assumption that wide speakers aren't a part of this and the calculations rely on the center line of the speakers. Most resources of this type seem to make the same assumption.


----------



## knappster007

Soulburner said:


> There is research showing that lateral reflections are very important and often preferred over their absence, and how vertical and lateral reflections differ in their effects on our perception due to the shape of our ears. Does your spreadsheet take this into account?
> 
> Otherwise, very cool.


I'm not aware of this research, but it does sound interesting. This spreadsheet only takes axial and tangential reflections and room modes in to account. Directionality is considered to be equal in the calculations.


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## sdurani

knappster007 said:


> I'm not aware of this research, but it does sound interesting.


Review of the historical research: 

http://www.wghwoodworking.com/audio/loudspeakers_and_rooms_for_sound_reproduction.pdf 

Start reading near the end, section 9.2, then go back to the beginning (if interested).


----------



## ereed

Swoosh830 said:


> I'm trying to decide between GIK corner Tri Traps and the Soffit traps for the front corners of my room. I already have a Tri Trap in each of the rear corners of the room as denoted by the attached floor plan. The front of the room is somewhat of a nook, so only one corner is a 'true corner' of the room. My front sound stage extends beyond the width of this nook with the L speaker being placed partially in front of the COATS closet. The R speaker is against the wall in front of the window.
> 
> I do have the ability to take measurements with REW. Is there any way of using this to determine which type of bass trap would work best in the front of my room, whether it's moving the mic near the corners or somewhere else in the room? I've also attached two recent measurements taken with ONLY the subwoofers and no room treatments or EQ. The blue line is the most recent after tweaking the placement of each sub. Since I was able to get within 10 dB with no treatments or EQ, would Tri Traps suffice in the front corners of the room? It's hard for me to justify the cost of the Soffit traps. Some say to add as many bass traps as can fit, while others say it's not always necessary. I've even heard Gene from Audioholics claim that there can be too much trapping and too much can require the levels of the subs to be raised (I'm paraphrasing, but it's from a recent video he did with measuring multiple subs with REW).
> 
> Thanks in advance for any advice.


First of all while I do respect Gene....there really is no such thing as too much bass trapping cause bass are hard to absorb and you won't absorb much below 40hz unless you have 3 feet thick of absorption. But you can over absorb mids/highs and its wise to add as many bass traps with some diffusion if you can to keep it lively while improving low bass decay.

The only diff between tri corner traps and soffit traps are that the latter absorb more low end. And if you want to absorb more low end without overabsorbing highs then add range limiter on it or scatter plates to keep from absorbing any highs. Performance wise, soffit traps are better for low end. But if you are tight on space tri corners are preferred. Gik has testing results graphs of absorption coef and sabins where you can compare the products to see how much each one compares to each other. 

Best way to do this is look at waterfall graph in REW and spectrogram to see how your low end is. Usually smaller rooms need more bass trapping than larger rooms due to bass waves bouncing back and forth depending on wavelength.


----------



## Swoosh830

ereed said:


> First of all while I do respect Gene....there really is no such thing as too much bass trapping cause bass are hard to absorb and you won't absorb much below 40hz unless you have 3 feet thick of absorption. But you can over absorb mids/highs and its wise to add as many bass traps with some diffusion if you can to keep it lively while improving low bass decay.
> 
> The only diff between tri corner traps and soffit traps are that the latter absorb more low end. And if you want to absorb more low end without overabsorbing highs then add range limiter on it or scatter plates to keep from absorbing any highs. Performance wise, soffit traps are better for low end. But if you are tight on space tri corners are preferred. Gik has testing results graphs of absorption coef and sabins where you can compare the products to see how much each one compares to each other.
> 
> Best way to do this is look at waterfall graph in REW and spectrogram to see how your low end is. Usually smaller rooms need more bass trapping than larger rooms due to bass waves bouncing back and forth depending on wavelength.


I appreciate the response. I attached frequency response and waterfall graphs I took this morning after finally connecting all speakers in my room and running Audyssey. During the measurements pictured below, I was in 2 channel stereo. All crossovers are at 80Hz.

In the frequency response graph, the brown line is the baseline. After tweaking the phase on Subwoofer 2, I was able to get the green line which I felt was a decent compromise. Other frequencies began to get ugly as I further adjusted the phase of Sub 2. I was unable to make any worthwhile changes when tweaking the distances of each sub in the Manual Setup section of Audyssey settings.

I'll admit, I'm not too well-versed in reading/comprehending waterfall graphs, but I'm guessing I've got lots of lingering activity around 20, 30, and ~42Hz. What that means in regards to bass traps, I'm not too sure. The corners that I'm able to fill are in the front of the room in the 'nook' area and I can stack them to the ceiling if need be. Due to a soffit and speakers on the rear wall, the one corner Tri Trap in each corner is all I can do for the rear of the room.

Thanks again for the input.


----------



## ereed

Swoosh830 said:


> I appreciate the response. I attached frequency response and waterfall graphs I took this morning after finally connecting all speakers in my room and running Audyssey. During the measurements pictured below, I was in 2 channel stereo. All crossovers are at 80Hz.
> 
> In the frequency response graph, the brown line is the baseline. After tweaking the phase on Subwoofer 2, I was able to get the green line which I felt was a decent compromise. Other frequencies began to get ugly as I further adjusted the phase of Sub 2. I was unable to make any worthwhile changes when tweaking the distances of each sub in the Manual Setup section of Audyssey settings.
> 
> I'll admit, I'm not too well-versed in reading/comprehending waterfall graphs, but I'm guessing I've got lots of lingering activity around 20, 30, and ~42Hz. What that means in regards to bass traps, I'm not too sure. The corners that I'm able to fill are in the front of the room in the 'nook' area and I can stack them to the ceiling if need be. Due to a soffit and speakers on the rear wall, the one corner Tri Trap in each corner is all I can do for the rear of the room.
> 
> Thanks again for the input.


Looks pretty good. 

For waterfall you want the lower spl limit to reach all the way down to noise floor of your room. Or go to your spectrogram and look at the peak which is 85db....you want to see how fast it decays 40db so the bottom of the graph should read 45, not 60 to show where the real resonances are. Don't worry about below 40hz too much. Those are hard to control. I have some ringing there as well but mine is mostly 22hz due to something electrical that is humming and won't stop. I don't hear it, but RTA picks it up. Adding more bass traps may not make waterfall look better or anything....but it certainly won't hurt either. Bass will be tighter all around.


----------



## Swoosh830

ereed said:


> Looks pretty good.
> 
> For waterfall you want the lower spl limit to reach all the way down to noise floor of your room. Or go to your spectrogram and look at the peak which is 85db....you want to see how fast it decays 40db so the bottom of the graph should read 45, not 60 to show where the real resonances are. Don't worry about below 40hz too much. Those are hard to control. I have some ringing there as well but mine is mostly 22hz due to something electrical that is humming and won't stop. I don't hear it, but RTA picks it up. Adding more bass traps may not make waterfall look better or anything....but it certainly won't hurt either. Bass will be tighter all around.


Thank you for that input. That makes sense regarding bass below 40Hz. It would take an awful lot to help with that.

I'm leaning towards additional Tri-Traps in the front corners as opposed to soffits. They're also more cost effective if I were to purchase an additional pair and stack them in each corner. One thought concerning that... perhaps go full range with the lower traps and range limit the ones on top? I may be overthinking it, but the traps on top would be above ear level and I could get a bit more bass absorbed with the range limited traps up there.


----------



## ereed

Swoosh830 said:


> Thank you for that input. That makes sense regarding bass below 40Hz. It would take an awful lot to help with that.
> 
> I'm leaning towards additional Tri-Traps in the front corners as opposed to soffits. They're also more cost effective if I were to purchase an additional pair and stack them in each corner. One thought concerning that... perhaps go full range with the lower traps and range limit the ones on top? I may be overthinking it, but the traps on top would be above ear level and I could get a bit more bass absorbed with the range limited traps up there.


Get them with range limiters built in. Front wall is bass pressure zone and you don't need full range there.


----------



## Swoosh830

ereed said:


> Get them with range limiters built in. Front wall is bass pressure zone and you don't need full range there.


It was actually recommended by one of the GIK consultants that the traps in the front of the room be full range (at least the stuff at ear-level). However, I never fully understood why since they would be behind the front speakers and TV/stand so far away from the MLP. My L speaker isn't even going to be entirely in front of the trap denoted by the bottom '?' in the attached image. I understand sound travels back there too, but it seemed like range limited traps would be a good opportunity to absorb more bass. The Tri-Traps in the rear corners are full range and that made sense when it was recommended to me given the direction that my speakers are firing.

After thinking about your suggestion to go with the range limiters, it may be a good compromise between the amount of bass absorption and not spending the extra for the Soffits. Given how good things sound right now, I can't imagine I will miss the extra high end absorption back there that full range traps would give me.


----------



## ereed

Swoosh830 said:


> It was actually recommended by one of the GIK consultants that the traps in the front of the room be full range (at least the stuff at ear-level). However, I never fully understood why since they would be behind the front speakers and TV/stand so far away from the MLP. My L speaker isn't even going to be entirely in front of the trap denoted by the bottom '?' in the attached image. I understand sound travels back there too, but it seemed like range limited traps would be a good opportunity to absorb more bass. The Tri-Traps in the rear corners are full range and that made sense when it was recommended to me given the direction that my speakers are firing.
> 
> After thinking about your suggestion to go with the range limiters, it may be a good compromise between the amount of bass absorption and not spending the extra for the Soffits. Given how good things sound right now, I can't imagine I will miss the extra high end absorption back there that full range traps would give me.


I'd put the full range tri traps in the rear corners and get range limiters tri traps in front corners. On rear wall it would be good to go with bass traps and diffusion such as Alpha 6A to keep room lively. Whats your RT60 from 250hz to 4000hz? Do you have any other panels other than just 2 tri traps currently?

If you don't have panels on ceiling or side walls, its possible GIK says full range so you can absorb some full range energy. It all depends on if you have or plan on doing other first reflection points, etc.


----------



## Swoosh830

ereed said:


> I'd put the full range tri traps in the rear corners and get range limiters tri traps in front corners. On rear wall it would be good to go with bass traps and diffusion such as Alpha 6A to keep room lively. Whats your RT60 from 250hz to 4000hz? Do you have any other panels other than just 2 tri traps currently?
> 
> If you don't have panels on ceiling or side walls, its possible GIK says full range so you can absorb some full range energy. It all depends on if you have or plan on doing other first reflection points, etc.


Yeah I do have other panels in the room. I have 12 sq. ft. of 4" thick panels on the rear wall, the center of the front wall has 20 sq. ft. of 6" thick panels, and then I have several 2" thick panels at various reflection points on the side walls (about 28 sq. ft. worth).

I don't have anything on the ceiling yet. I'm not sure I can get past the PITA it will be to install them and how obtrusive they may look in my room, but I had considered GIK 244s for that.

With the treatments I currently have, slap echo has been drastically reduced. I know that's not a true gauge of how it will help my theater, but I do have treatments that have tamed some of the high end.


----------



## PretzelFisch

Swoosh830 said:


> It was actually recommended by one of the GIK consultants that the traps in the front of the room be full range (at least the stuff at ear-level). However, I never fully understood why since they would be behind the front speakers and TV/stand so far away from the MLP. My L speaker isn't even going to be entirely in front of the trap denoted by the bottom '?' in the attached image. I understand sound travels back there too, but it seemed like range limited traps would be a good opportunity to absorb more bass. The Tri-Traps in the rear corners are full range and that made sense when it was recommended to me given the direction that my speakers are firing.
> 
> After thinking about your suggestion to go with the range limiters, it may be a good compromise between the amount of bass absorption and not spending the extra for the Soffits. Given how good things sound right now, I can't imagine I will miss the extra high end absorption back there that full range traps would give me.


sound is a wave it wraps around and behind the speaker to hit the back wall. High frequencies do this a little less.


----------



## Swoosh830

PretzelFisch said:


> sound is a wave it wraps around and behind the speaker to hit the back wall. High frequencies do this a little less.


When you say back wall, do you mean behind the seating or behind the TV and front sound stage?


----------



## Soulburner

I believe he meant front wall, behind the speakers. Frequencies up to around 350Hz will behave in that way.


----------



## ereed

Swoosh830 said:


> Yeah I do have other panels in the room. I have 12 sq. ft. of 4" thick panels on the rear wall, the center of the front wall has 20 sq. ft. of 6" thick panels, and then I have several 2" thick panels at various reflection points on the side walls (about 28 sq. ft. worth).
> 
> I don't have anything on the ceiling yet. I'm not sure I can get past the PITA it will be to install them and how obtrusive they may look in my room, but I had considered GIK 244s for that.
> 
> With the treatments I currently have, slap echo has been drastically reduced. I know that's not a true gauge of how it will help my theater, but I do have treatments that have tamed some of the high end.


Looks like you have enough absorption in the room. I would just do range limiters for other traps and add diffusion on the rear wall or side wall if you want. In REW go to your RT60 and look at 250 to 4000hz. That will tell you how lively your room is.


----------



## sdurani

Swoosh830 said:


> It was actually recommended by one of the GIK consultants that the traps in the front of the room be full range (*at least the stuff at ear-level*). However, I never fully understood why since they would be behind the front speakers and TV/stand so far away from the MLP.


Maybe they want those panels to absorb front wall reflections that can combine with the direct sound from the speakers to cause boundary cancellations.


----------



## Swoosh830

ereed said:


> Looks like you have enough absorption in the room. I would just do range limiters for other traps and add diffusion on the rear wall or side wall if you want. In REW go to your RT60 and look at 250 to 4000hz. That will tell you how lively your room is.


Thanks for the suggestions. I'll take a look at that graph the next time I take measurements.



sdurani said:


> Maybe they want those panels to absorb front wall reflections that can combine with the direct sound from the speakers to cause boundary cancellations.


That's a great point, and brings me back to the idea of full range traps on the bottom with range limited stacked on top.


I attached some pictures of the front 'nook' area that we've been discussing (apologies for the poor lighting), as well as the rear of the room. I really appreciate all the feedback.


----------



## nirvana_av

PretzelFisch said:


> sound is a wave it wraps around and behind the speaker to hit the back wall. High frequencies do this a little less.


High frequencies do this not at all, above the baffle step frequency.


----------



## Swoosh830

ereed said:


> Looks like you have enough absorption in the room. I would just do range limiters for other traps and add diffusion on the rear wall or side wall if you want. In REW go to your RT60 and look at 250 to 4000hz. That will tell you how lively your room is.


I'm even less familiar with RT60 graphs than I am with waterfall graphs, but I took some measurements yesterday and attached the results below. I couldn't even begin to determine whether they are good, bad, or somewhere in between.

For the heck of it, I included the SPL results as well.


----------



## ereed

Swoosh830 said:


> I'm even less familiar with RT60 graphs than I am with waterfall graphs, but I took some measurements yesterday and attached the results below. I couldn't even begin to determine whether they are good, bad, or somewhere in between.
> 
> For the heck of it, I included the SPL results as well.


You have enough absorption.....RT60 looks good. Do rest of bass traps with range limiters for front wall and bass traps with diffusion on rear wall. You do not need anymore full broadband absorption in my opinion.

You want it to fall between .2 and .5 seconds for decay. Here is mine along with showing the settings on screen how to get the bars. Normally for small rooms the .2 to .3 is the goal. For larger rooms .3 to .5 seconds is the goal.


----------



## Swoosh830

ereed said:


> You have enough absorption.....RT60 looks good. Do rest of bass traps with range limiters for front wall and bass traps with diffusion on rear wall. You do not need anymore full broadband absorption in my opinion.
> 
> You want it to fall between .2 and .5 seconds for decay. Here is mine along with showing the settings on screen how to get the bars. Normally for small rooms the .2 to .3 is the goal. For larger rooms .3 to .5 seconds is the goal.


Awesome, I really appreciate the feedback and for the basics of what to look for in the RT60 graph. I already have the 4" thick panels on the rear wall with full range Tri-Traps in the rear corners. I attached a few pictures of my room a few posts back for reference. It's right around 2,000 cu. ft. That's good news that I can put the idea of hanging treatments on the ceiling to rest based on the amount of absorption I already have in place.

Based on your advice for the front corners that have yet to be treated, I'll likely go with range limited Tri-Traps. After adjusting the physical location of the sub in the front of my room closer to the wall, the Soffits would just be too big. I then took more measurements after some changes (phase, distance settings, etc.) and came up with the graph attached. Getting there...

Thanks again for recommending the RT60 measurements. I'll open up that file and make the changes necessary to get the bars so it's easier to read. It's always fun to learn something new that will help improve my room.


----------



## ereed

Swoosh830 said:


> Awesome, I really appreciate the feedback and for the basics of what to look for in the RT60 graph. I already have the 4" thick panels on the rear wall with full range Tri-Traps in the rear corners. I attached a few pictures of my room a few posts back for reference. It's right around 2,000 cu. ft. That's good news that I can put the idea of hanging treatments on the ceiling to rest based on the amount of absorption I already have in place.
> 
> Based on your advice for the front corners that have yet to be treated, I'll likely go with range limited Tri-Traps. After adjusting the physical location of the sub in the front of my room closer to the wall, the Soffits would just be too big. I then took more measurements after some changes (phase, distance settings, etc.) and came up with the graph attached. Getting there...
> 
> Thanks again for recommending the RT60 measurements. I'll open up that file and make the changes necessary to get the bars so it's easier to read. It's always fun to learn something new that will help improve my room.


Not sure what your plan is but lets assume you wanted to add more bass trapping and make room livelier at the same time. You could repurpose your 4 inch thick panels to the ceiling and put something such as Alpha 6A on rear wall. Just another option.


----------



## Swoosh830

ereed said:


> Not sure what your plan is but lets assume you wanted to add more bass trapping and make room livelier at the same time. You could repurpose your 4 inch thick panels to the ceiling and put something such as Alpha 6A on rear wall. Just another option.


I appreciate the suggestion. I think for now I'm going to start with adding a pair of GIK Tri-Traps w/ range limiters for the front corners of the room and see how much that improves things. I'll make a decision later on whether or not I want to stack another pair on top of them.


----------



## Mocs123

I'm finishing my theater build and need to figure out my acoustical treatments. My room is 21'x16'x8' with about 25" of that behind my acoustically transparent screen. I have two layers of 1" Linacoustic behind my screen and have some left over so I would like to build panels with the remnants of that. I'm thinking two 2'x4' panels vertically on each wall with a single layer of Linacoutic under some AT fabric. On the back wall I was thinking of a horizontal 2'x4' panel above my two chairs - would a double layer rather than a single layer of 1" Linacoustic be better? Also I'm planning on building a "false" panel as a door to hide by equipment - basically a 2'x4' frame covered in AT fabric with no treatment material inside so air can still flow to the equipment. Opposite of that on the other long wall is a door that's steel going to an unfinished basement. Would it make since to cover it with a 2'x4' panel with a layer of Linacoustic inside? I'm not sure how I would attach it, but I could probably figure something out with magnets. 



Any thoughts or suggestions are appreciated. Pictures below.


----------



## Kal Rubinson

Mocs123 said:


> I'm finishing my theater build and need to figure out my acoustical treatments. My room is 21'x16'x8' with about 25" of that behind my acoustically transparent screen. I have two layers of 1" Linacoustic behind my screen and have some left over so I would like to build panels with the remnants of that. I'm thinking two 2'x4' panels vertically on each wall with a single layer of Linacoutic under some AT fabric. On the back wall I was thinking of a horizontal 2'x4' panel above my two chairs - would a double layer rather than a single layer of 1" Linacoustic be better? Also I'm planning on building a "false" panel as a door to hide by equipment - basically a 2'x4' frame covered in AT fabric with no treatment material inside so air can still flow to the equipment. Opposite of that on the other long wall is a door that's steel going to an unfinished basement. Would it make since to cover it with a 2'x4' panel with a layer of Linacoustic inside? I'm not sure how I would attach it, but I could probably figure something out with magnets. Any thoughts or suggestions are appreciated. Pictures below.


Using lots of 1" thick will deaden the high frequencies, have negligible effect on midrange frequencies and none at all in the bass where room modes need attention. Do some measurements and get some proper stuff for fixing what needs to be fixed.


----------



## Mocs123

Kal Rubinson said:


> Using lots of 1" thick will deaden the high frequencies, have negligible effect on midrange frequencies and none at all in the bass where room modes need attention. Do some measurements and get some proper stuff for fixing what needs to be fixed.



What do you recomend? When I checked OC 703's acoustical specs it didn't look that much different than Linacoustic.


----------



## HopefulFred

Mocs123 said:


> What do you recomend?


I don't know what Kal would recommend, but you might check out what I did. I built a Helmholtz style bass trap to take up most of the space behind my AT screen. My theater is similar dimensions to yours, and I think I got pretty good results from that.
https://www.avsforum.com/forum/19-d...2262-once-future-theater-57.html#post50093337
Sorry about the images, I have not relocated all my photos from photobucket, so I run out of bandwidth about 1 week into every month. Check back Sunday if you can't make out what I've done.


----------



## Mocs123

HopefulFred said:


> I don't know what Kal would recommend, but you might check out what I did. I built a Helmholtz style bass trap to take up most of the space behind my AT screen. My theater is similar dimensions to yours, and I think I got pretty good results from that.
> https://www.avsforum.com/forum/19-d...2262-once-future-theater-57.html#post50093337
> Sorry about the images, I have not relocated all my photos from photobucket, so I run out of bandwidth about 1 week into every month. Check back Sunday if you can't make out what I've done.



Perhaps the panel on the back wall with 4" think Acoustimac Eco Core insulation? It's supposed to be better with low frequencies than OC703 or Rockwool. Then I could use my leftover Linacoustic for 1" side wall panels.


----------



## Kal Rubinson

Mocs123 said:


> What do you recomend? When I checked OC 703's acoustical specs it didn't look that much different than Linacoustic.


It's not so much the material as it is the thickness (or lack thereof). I suggest you consult this forum or other sites with information about room modes and reflections and how to deal with them.


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## Mocs123

I can use two layers of 1" Linacustic on the sidewall panels and four layers on the back wall. I'm going to try and put panels on the first reflection points


----------



## flyers10

What's a good way to hang ceiling panels? I was thinking either use some French cleats or use some eye hooks connected by zip tie.


----------



## OJ Bartley

Mocs123 said:


> I can use two layers of 1" Linacustic on the sidewall panels and four layers on the back wall. I'm going to try and put panels on the first reflection points


I'm far from an expert, but doubling up would be a step in the right direction. Can you fit 3 layers at the sides? Maybe one panel with 2 layers and one with 3 layers to vary the effect. I'd also consider using diffusion in the rear, there are lots of tutorials for DIY "skyline" or "quadratic residue diffusers (QRD)" on these and other forums. It looks like you have a reasonable amount of space on those walls, experiment with combinations!


----------



## elitemikes

I was about to order all of my fabric from a GOM re-seller then I thought I should ask if anyone found any good alternatives at a place like Joanne fabrics. I may hide my surrounds, but for the most part, its' only for treatments.


----------



## grassy

Martini Absorb was what i went with HD100 with NRC rating of 1.00 which was great for my needs.Ceilings will be done next year some time with the option of framing them if need to. There is no hazards while working with this product at all. Its non itchy.The product is a polyester fibre. It also costs half the price of some other brands and at the same time it is used in commercial buildings here in Australia. And it works great as i have personally tested it with my ears.Results were fantastic.


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## Mashie Saldana

So what is the latest theory for ceiling treatment in combination with immersive sound?

If I were to move a mirror around I would probably see speakers in the reflection pretty much every location.

Anyone added absorption to the entire ceiling?


----------



## Jan3

Couldn't this work on the wall as a cheap diffuser? 15 euros, 70x200cm which is about 2.3 feet x 6.5 feet


https://www.ikea.com/be/nl/images/products/luroey-slatted-bed-base__0268301_PE406268_S5.JPG?f=s


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## Rovari

ncabw said:


> Thanks for the reply’s.
> 
> I had the hockey player panel originally at the 1st reflection point. I moved it forward and the Jordan picture further back. Leaving my 1st reflection point open. This is where I will build the new panel. Sounds like its best to use the burlap material then. Also I moved the first panel up because I didn’t want to throw it away since I like them and I made 4 of them.
> 
> From your previous reply
> 
> -I have 2 corner base traps on the back wall corners
> - I have 5 ceiling panels
> - my rooms 22’ long and I’m siting around the 9-6” form the front wall.
> 
> As for diffusers I would like to make some but I haven’t found a good site in how to do it.
> 
> Her are some pics form when I was building the ceiling panels and corner bass trap.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk


FYI... in doing research on the right materials for sound absorption I have read that using fiberglass / rock wool or owens corning 703 is not recommended due to the fiberglass fibers that are released. If it can breathe the fibers will be released into your space and breathed in...because it is not an organic material your lungs will be stuck with these and they can cause health problems. I had planned to make panels using roxul until I had read this article.


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## pkinneb

Rovari said:


> FYI... in doing research on the right materials for sound absorption I have read that using fiberglass / rock wool or owens corning 703 is not recommended due to the fiberglass fibers that are released. If it can breathe the fibers will be released into your space and breathed in...because it is not an organic material your lungs will be stuck with these and they can cause health problems. I had planned to make panels using roxul until I had read this article.


My question would be how exactly will those fibers be released? They are attached to the wall so during installation sure but once on the wall how will they be released?


----------



## Rovari

pkinneb said:


> My question would be how exactly will those fibers be released? They are attached to the wall so during installation sure but once on the wall how will they be released?


My understanding is that if the material will let air through (which it should) the fabric will have the potential to let fibers through as well.


----------



## pkinneb

Rovari said:


> My understanding is that if the material will let air through (which it should) the fabric will have the potential to let fibers through as well.



If the OC703 is attached to the wall where is the air that will move the fibers coming from?


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## dynfan

Rovari said:


> pkinneb said:
> 
> 
> 
> My question would be how exactly will those fibers be released? They are attached to the wall so during installation sure but once on the wall how will they be released?
> 
> 
> 
> My understanding is that if the material will let air through (which it should) the fabric will have the potential to let fibers through as well.
Click to expand...

OC703 was originally sold as duct liner board. If you are cutting the board and compressing it, it can release fiber. Once in place it will not based on its construction. Thus it is widely used in construction and acoustic applications on a wide scale.


----------



## Rovari

dynfan said:


> OC703 was originally sold as duct liner board. If you are cutting the board and compressing it, it can release fiber. Once in place it will not based on its construction. Thus it is widely used in construction and acoustic applications on a wide scale.


Thanks for the clarification. So to be clear, using rock wool would be an issue but not an issue the Owens Corning 703?


----------



## dynfan

Rovari said:


> dynfan said:
> 
> 
> 
> OC703 was originally sold as duct liner board. If you are cutting the board and compressing it, it can release fiber. Once in place it will not based on its construction. Thus it is widely used in construction and acoustic applications on a wide scale.
> 
> 
> 
> Thanks for the clarification. So to be clear, using rock wool would be an issue but not an issue the Owens Corning 703?
Click to expand...

I think either material will be fine once in place. It’s easy to be overly cautious but my concern is only during construction. 

Nearly every cubicle made for use in an office contains acoustic absorption material of some sort. In many cases fiberglass or wool.


----------



## Rovari

dynfan said:


> I think either material will be fine once in place. It’s easy to be overly cautious but my concern is only during construction.
> 
> Nearly every cubicle made for use in an office contains acoustic absorption material of some sort. In many cases fiberglass or wool.


Thanks again Dynfan. I was all ready to go on some DIY Roxul panels when I read about this. Now I will continue...cheers!


----------



## dynfan

Rovari said:


> dynfan said:
> 
> 
> 
> I think either material will be fine once in place. Itâ€™️s easy to be overly cautious but my concern is only during construction.
> 
> Nearly every cubicle made for use in an office contains acoustic absorption material of some sort. In many cases fiberglass or wool.
> 
> 
> 
> Thanks again Dynfan. I was all ready to go on some DIY Roxul panels when I read about this. Now I will continue...cheers!
Click to expand...

No problem. Your home is filled with fiberglass batting and many other things that are more likely to be disturbed and airborn. As long as you are smart/careful when building that’s the important part.

Not to mention that 703 has arguably some of the best absorption properties when compared to other materials.


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## Mocs123

Would these work well for some diffusion panels in my HT? They are inexpensive and lightweight so they should be easy to install.


----------



## dynfan

Mocs123 said:


> Would these work well for some diffusion panels in my HT? They are inexpensive and lightweight so they should be easy to install.


Am I reading it right that they are only 1” thick? If so The angle at which they reflect is narrow and could create some issues of their own. I would be inclined to choose something thicker . 

I previously used Auralex mini-fusors in an array on my back wall and filled them with 703. They worked very well and were 12” x 12” x about 7” deep.


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## Mocs123

dynfan said:


> Am I reading it right that they are only 1” thick? If so The angle at which they reflect is narrow and could create some issues of their own. I would be inclined to choose something thicker .
> 
> I previously used Auralex mini-fusors in an array on my back wall and filled them with 703. They worked very well and were 12” x 12” x about 7” deep.



I understand they aren't what I'm looking for since they are not thick enough. The Auralex mini-fusers look good, but are pricey. It seems like there would be a more affordable solution out there. I may try the DIY route but was looking for something inexpensive and lightweight. The DIY solutions out there look fairly time consuming and I have quite a few other projects on the table before I could start them.


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## Biggydeen

Need some help regarding difusers and absorber placement. I have a large room (8.8m width, 5.5m lenght) but got a slanted roof like this /\ all the way from the floor to top. From floor to cleiling is 3.3m

Basically meaning I have no direct reflection points on the side walls. The sound will bounce from the slanted ceiling to the floor and then back to the listening position. I do have reflection points higher up on the slanted ceiling. My floor is covered with a cheap carpet of 2mm at most. 

Because most rooms have reflection points on the side walls, what would acousticly be the best option for me? I doubt I need absorbsion on the side because sounds will not direclty reflect to the listening positions. On top of that, I have a black velvet curtain on the side with all kinds of stuff behind it (movingboxes full of old stuff). 

The slanted roof itself is made of wooden plates with a thick layer of rockwool behind it for isolation. I also treated 3/4 of the slanted roof and screen wall with black velvet. 

On the straight wall is my projector screen (~ 122 inch). On the opposite wall is my projector. 

See attachment for clarification (forgive my paint skills..). I've marked the spots I want to treat:

So I was thinking:

- 1 & 2: absorbtion panels directly behind the speakers. The speakers are ~ 40- 50cm from the wall. (got 2 towers and center speaker)
- 3 & 4: Absorbtion panels on the first reflection points on the slanted ceiling
- 5 & 6: Not sure if these surfaces need any treatment. I do have a center speaker placed at 5 and a big sub right next to it.
- 7 : My back wall only consists of the projector and 2 surround speakers. It's a non treated very thick reinforced (with steel) concrete wall. I'm not sure what to place here (absorbers or difusers. Difusers seem best to not kill the sound in the room).
- 8 : Directly beneath my projector is a big gap leading downstairs. Without any sealing doors. It's an open stair directly connected (without doors or anthing) to the second floor.
- 9: this is were I have a desk with pc/chair and location of my receiver's
- 10: piled up junk (old chair, movingboxes and other stuff)

My seating position is in the middle of the room about 2m from the back wall and 3m from the front wall. Direclty beside the couch are 2 surround speakers. (I'm using an 7.1.4 Dolby Atmos setup)

So in short:

- I want to place absorbers on spots 1,2,3,4. Are these good spots for absorbers? (Will use the mirror technique to identify the best spot)
- I'm not sure about placing absorbers on spot 5 & 6
- I'm not sure how I should treat the complete back wall 7. Most likely difusers to not kill the sound in the room?
- Am I missing something? I'm using an 7.1.4 Dolby Atmos setup.


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## Dirt9

Quick question on corner bass trapping.

Rolls of pink fluffy still in plastic floor to ceiling vs pre built corner traps.

I'm sure it's been documented but ....


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## Mashie Saldana

Dirt9 said:


> Quick question on corner bass trapping.
> 
> Rolls of pink fluffy still in plastic floor to ceiling vs pre built corner traps.
> 
> I'm sure it's been documented but ....


Pink fluffy that isn't compressed and at least a foot deep.


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## Dirt9

What would be recommended here.fill in around the screen with sound panels.. or hang sound panels on the wall behind the screen and fill in around screen with black fabric


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## Ladeback

Dirt9 said:


> What would be recommended here.fill in around the screen with sound panels.. or hang sound panels on the wall behind the screen and fill in around screen with black fabric


A lot of members use black velvet over panels they build. You can also use it around the screen to control light reflection. 

https://www.avsforum.com/forum/110-diy-screen-section/2038690-black-velvet-fabric.html


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## jeffreynmandy

Kal Rubinson said:


> Using lots of 1" thick will deaden the high frequencies, have negligible effect on midrange frequencies and none at all in the bass where room modes need attention. Do some measurements and get some proper stuff for fixing what needs to be fixed.



I have lots of 1.5" owens 703. Would one layer of 1.5" with a 1" air gap perform similar to 2 layers stacked to 3" and mounted directly to the wall? I don't really want to make my panels more than 3-4" thick.


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## sdurani

jeffreynmandy said:


> I have lots of 1.5" owens 703. Would one layer of 1.5" with a 1" air gap perform similar to 2 layers stacked to 3" and mounted directly to the wall?


1.5" w/ 1" air gap (blue) versus 3" on wall (green). 










http://www.acousticmodelling.com/porous.php


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## marto2009

Hi to you all, 

I have been reading this thread, and I am kind of lost regarding how "dead" my room should be. 

My room is quite small, (L)2,40m x (W)3,00m x (H)2,70m with carpet on the floor, rear wall solid concrete and front wall made of "hollow"/panel wall (I don't know how to say it).-

I have a ton of reverberation and people in these forum kindly recommend me to treat the front (behind the TV) and rear wall (behind the couch), so I purchased 2 panels of 2" Owens Corning SelectSound® Black Acoustic Board and started making some acoustic panels measuring 90cm x 60cm each, mounted at 1/4 inch from the wall. 

-.I plan on mounting 4 in the rear wall, right where the couch ends.
-. In the front wall i am planning on installing panels right behind the front speakers. 
-. Also, I will install stands for my surround speakers. These stands will have a "front" face of the same Owens Corning acoustic material. 
-. Side walls are un-treatable. One is a closet/wardrove and the other is the window with thick rubber curtains. 

My questions are:
a) Is it enough or is it to much? 
b) Should I also install an horizontal panel over the TV? 
c) The couch's back plus the 90cm of the panel is around 1,80mt high... what about the "almost" 80cm from there up to the ceiling? should I also install panels over there? 

This is a multichannel room, dedicated only to TV and movies. 

Looking forward to your help!

Cheers


----------



## Stephen Cagle

What do you guys think of these diffuser panels. Saw them on a browser ad.... seems too cheap. not sure how they would do free shipping if they are made out of wood they'd be pretty heavy. Thinking about buying a pair...



https://www.nynelife.com/products/acoustic-sound-panels?variant=31462732529715


----------



## BIC2

Stephen Cagle said:


> What do you guys think of these diffuser panels. Saw them on a browser ad.... seems too cheap. not sure how they would do free shipping if they are made out of wood they'd be pretty heavy. Thinking about buying a pair...
> 
> https://www.nynelife.com/products/acoustic-sound-panels?variant=31462732529715


Yes, does seem like too good a deal. Can't find any other info about the seller on the great world wide web. No manufacturer or country of origin. Seems a bit risky.


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## Stephen Cagle

Yeah, I agree. Think I'm going to pass on trying those out


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## jconjason

Dirt9 said:


> This was not expectedWhat do you guys think??
> I'm starting to treat my theater room so I made six 4" roxul-60 panels and framed up six 6" rock wool batts to get started.
> Thought i'd start behind my AT screen which has three PSA speakers behind it that are 2.5' from the from wall.
> I grabbed three of the roxul-60 panels and put them behind the LCR and measured the center channel and to my surprise the graphs look worse.
> Blue line is with no treatments in the room,red is with three panels behind the LCR


It can happen. Just throwing up panels without knowing where, can cause what you found.


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## Dirt9

Is not recommended to absorb behind a audio transparent screen to eliminate sound bouncing back or is it not always a problem?


----------



## OJ Bartley

It might also mean that the particular panels you've built are targeting the wrong frequencies. You might be able to change the frequency by putting kraft paper or poly sheeting on the face of the panel. I think that would raise the effective frequency, and with a little luck it might push you from that ~270Hz area up to the problem area around ~350Hz? I'm sure that there are ways to determine the target frequencies, but some trial and error since the panels are already built wouldn't be too hard.


----------



## Mashie Saldana

Dirt9 said:


> This was not expectedWhat do you guys think??
> I'm starting to treat my theater room so I made six 4" roxul-60 panels and framed up six 6" rock wool batts to get started.
> Thought i'd start behind my AT screen which has three PSA speakers behind it that are 2.5' from the from wall.
> I grabbed three of the roxul-60 panels and put them behind the LCR and measured the center channel and to my surprise the graphs look worse.
> Blue line is with no treatments in the room,red is with three panels behind the LCR


Did you have any room correction enabled during any of the measurements?

Also adding treatments can move nulls and peaks in a room.


----------



## Dirt9

Mashie Saldana said:


> Did you have any room correction enabled during any of the measurements?
> 
> Also adding treatments can move nulls and peaks in a room.


This was not expectedWhat do you guys think??
I'm starting to treat my theater room so I made six 4" roxul-60 panels and framed up six 6" rock wool batts to get started. 
Thought i'd start behind my AT screen which has three PSA speakers behind it that are 2.5' in from the front wall.
I grabbed three of the roxul-60 panels and put them behind the LCR and measured the center channel and to my surprise the graphs look worse.
Blue line is with no treatments in the room,red is with three panels behind the LCR,disregard the spf level,i did not calibrate the input level.

There is a antimode 8033-sii inline,cross over is at 110hz,any lower and I get a hole at 80hz.no other room correction in use.
Main listening position is at 7' from the back wall.Any help would be great,Thanks


----------



## jconjason

Dirt9 said:


> This was not expectedWhat do you guys think??


Have you tried putting them on the side walls between your MLP and the screen? Have you done the mirror test to find where the reflections would be?


----------



## Dirt9

Mashie Saldana said:


> Did you have any room correction enabled during any of the measurements?
> 
> Also adding treatments can move nulls and peaks in a room.





jconjason said:


> Have you tried putting them on the side walls between your MLP and the screen? Have you done the mirror test to find where the reflections would be?[/
> 
> I only have 15" on each side of the screen and have the first reflections marked but not treated.for some reason I thought it would be best to start with the screen wall,maybe it would be best to do the first reflections first and then evaluate?
> The LR speakers do fit in that 15" space between the screen edge and the wall but would be physically jammed in there with no room for toe in.
> I have the center channel sitting on top of the sub behind the screen.
> 
> center+subs measurement


----------



## HopefulFred

Am I the only one who sees these measurements as expected? 

To me, it looks like there was some bass/midbass boost coming from the screen wall reflection (SBIR) and the absorber took that away. What I don't know for sure is if this creates a problem. If you want a little more baffle step compensation, relocate the panels and try again.


----------



## Peter Norin

Hi! What kind of acoustic panel do you recommend me?


----------



## Mashie Saldana

Peter Norin said:


> Hi! What kind of acoustic panel do you recommend me?


In what type of system and for what goal?


----------



## Peter Norin

Mashie Saldana said:


> In what type of system and for what goal?


For my home cinema system.


----------



## Peter Norin

I found this. What are your opinions about this acoustic panel?

https://perfect-acoustic.com/termek/acoustic-panel-with-diffuser/


----------



## Blackdevil77

With this room layout, what sort of treatments would you use and where? I don't want the room to be overly dead. Maybe an absorption/diffusion at the first reflection points and diffusion in the back? Would that be enough?


----------



## harrisu

Hi guys,
Anyone knows how to build an absorptive panel that would reflect above ~5000Hz? I have heard that using FRK paper will reflect higher frequencies 
https://www.buyinsulationproductstore.com/frk-paper-pack-of-12-sheets/ but at what point does it start reflecting? I basically want to absorb below 5000 to make dialog/upper midbass clear and reflect the higher frequency to keep the timber alive.

Thx in advance.


----------



## LittleLarry

Trying to get an idea of the best stylish panels I could get to fill in areas for this impossible build. 

I've read that sometimes it's best to fill in cabinets with treatments but if I fill them in completely, it makes the room feel a lot smaller. Can I just add a couple inches of treatment in the backs and sides of each shelf slot and maybe some larger corner bass traps in the Pro-logic IIz height speaker stand area? The width of this room is only 12 feet across. The depth of the built in fireplace mantel shelves are almost 2 feet deep.

All the speakers are front ported except the center channel but it's almost 2 feet from the fireplace.

Current:










Future State (Planned Projector Screen Placement):










Current Known Broken Rules for this Build:

1. LCR mains configured as inversed arc of sound.
2. Subwoofer sort of blocks right main.
3. Mains and IIz Height LR speakers too close to walls.
4. Bass traps and other acoustic room treatments missing.
5. LR Surrounds installed too close to mains, far from optimal location.
6. Aesthetics are horrid. In need of emergency style infusion.


----------



## harrisu

ereed said:


> You have enough absorption.....RT60 looks good. Do rest of bass traps with range limiters for front wall and bass traps with diffusion on rear wall. You do not need anymore full broadband absorption in my opinion.
> 
> You want it to fall between .2 and .5 seconds for decay. Here is mine along with showing the settings on screen how to get the bars. Normally for small rooms the .2 to .3 is the goal. For larger rooms .3 to .5 seconds is the goal.


Hey ereed, I'm doing the acoustic treatment in my sealed 20x12x8 room. Here is the RT60. Can you please evaluate how this looks? I believe my room is more towards small?


----------



## ereed

harrisu said:


> Hey ereed, I'm doing the acoustic treatment in my sealed 20x12x8 room. Here is the RT60. Can you please evaluate how this looks? I believe my room is more towards small?


What you wanna look at is between 200hz to 4000hz area. The issues I see just from the graph alone is I think the reverberation time is too short between 450hz and all the way up 5000hz which can make room sound little dead. If you want to bright that up then you would add diffusion.

The other issue is the rt60 line varies across frequency bands where you can see 200hz to 450hz area is much higher reverb time compared to above 450hz. You ideally want all balanced throughout whole freq range. 

Check out this link for more explaination and examples. http://www.acousticfrontiers.com/understanding-small-room-reverberation-time-measurements/


----------



## harrisu

ereed said:


> What you wanna look at is between 200hz to 4000hz area. The issues I see just from the graph alone is I think the reverberation time is too short between 450hz and all the way up 5000hz which can make room sound little dead. If you want to bright that up then you would add diffusion.
> 
> The other issue is the rt60 line varies across frequency bands where you can see 200hz to 450hz area is much higher reverb time compared to above 450hz. You ideally want all balanced throughout whole freq range.
> 
> Check out this link for more explaination and examples. http://www.acousticfrontiers.com/understanding-small-room-reverberation-time-measurements/


Thx for the link. I read the article and very useful indeed. A few very interesting point based on the article from Nyal is the following


> Single figure T60 measurements cannot do much more in a small room than tell you whether a room is overly live or overly dead. More useful is to look at how sound decays across the critical midrange frequency bands above the transition frequency from 250Hz to 4kHz and to examine whether the speed of this decay is consistent over time


Then he again repeats the point as 


> Time taken for sound to decay 60dB (T60) should be between 0.2s and 0.5s from 250Hz to 4kH
> T20 and T30 should be within +/- 25% from 250Hz to 4kHz when using one third octave smoothed bands.


So clearly, we need to look starting from 250Hz up to 4000. Doing so revealed the following. 










First, you can see that I do have good consistency. Its well within 25% of threshold. So no inconsistency issue there. But here is a very interesting observation. I have two graphs in the image. First one GREEN that represents my room with all the absorbers/diffusers and 2nd is RED which I took after removing all the absorbers. The only absorbers left are following
1 - whole floor covered with carpet
2 - front whole wall covered with Linacoustic.

I even took off Linacoustic right behind the center channel and still it wouldn't move up. Am I doing something wrong here? Is my graph setting off?


----------



## JonnyVee

Looking for a little advice. I can only find Comfortboard 80 1.5” locally. I could special order 2”, but it’ll take awhile to come in. So I’m thinking just use 1.5” which means my options are:

1. 1.5” 80 in a 2” deep frame (Minimal air gap)
2. 1.5” 80 in a 3” deep frame (1.5” air gap)
3. Double up the 80 for 3” of insulation in a 3” deep frame (no air gap)

I really don’t want to go with 4” deep frames as the area is already quite small. 

I’ll be adding on the side wall, back wall and ceiling.


----------



## Dirt9

Hello everyone.im looking for advice on soffit bass traps.what I'm building are 17"square traps that are 48" tall filled with safe and sound,stacked floor to ceiling in the corners.i want them to not absorb the high frequency.what would be recommended?.i was thinking 1/8" fiber board on two sides and leaving the other two side open then wrapped in fabric that way they could be rotated if broadband was desirable.is this a good idea??


----------



## Dirt9

JonnyVee said:


> Looking for a little advice. I can only find Comfortboard 80 1.5â€Â locally. I could special order 2â€Â, but itâ€™️ll take awhile to come in. So Iâ€™️m thinking just use 1.5â€Â which means my options are:
> 
> 1. 1.5â€Â 80 in a 2â€Â deep frame (Minimal air gap)
> 2. 1.5â€Â 80 in a 3â€Â deep frame (1.5â€Â air gap)
> 3. Double up the 80 for 3â€Â of insulation in a 3â€Â deep frame (no air gap)
> 
> I really donâ€™️t want to go with 4â€Â deep frames as the area is already quite small.
> 
> Iâ€™️ll be adding on the side wall, back wall and ceiling.


Honestly I would make 3"panels.what I did was stack 2" to make 4"and hot glue then together.
then I went to home depot and got some 10' plastic edge protector for sheet rock and some hot glue.
you just go up the edge of the panel you made hot gluing as you go.make a 45 degree notch but don't cut all the way through to bend around the corners and continue on until you get back to where you started.do this on both sides so it holds the panels together then wrap in cloth and hang on a hook.


----------



## Dirt9

Dirt9 said:


> Hello everyone.im looking for advice on soffit bass traps.what I'm building are 17"square traps that are 48" tall filled with safe and sound,stacked floor to ceiling in the corners.i want them to not absorb the high frequency.what would be recommended?.i was thinking 1/8" fiber board on two sides and leaving the other two side open then wrapped in fabric that way they could be rotated if broadband was desirable.is this a good idea??


Also I had a idea of using faced R19 and hanging them instead of the safe and sound.i would use 4 batts and leave the paper on all of them.would leaveing the paper on all of the batts inside the soffit trap be beneficial or not?


----------



## audiomirage

I was wondering if someone would be willing to give me some advice on sound treatment using the material that I have listed below. 

A friend of mine gave me 13 left over Acoustic Panels from a job he did. ( https://acoufelt.com/product-category/panel/solid/ ) Here is a quick bit of info regarding the panels from thier website: _(Acoufelt wall and ceiling panels achieve a minimum NRC of 0.45 and are available in a variety of solid colourways. Panels come in a standard size of 2440 x 1220mm with a thickness of 12 or 24mm. Depending on the acoustic demands of the room, solid panels can be applied to cover the entire wall or ceiling, or as a standalone feature, adding colour and texture to the space.)_

I plan on cutting the 4x8 panels into Squares, and then stack two or three to make a diamond shape pattern with different colors and sizes. (I have Black, Navy Blue, and Grey).

Attached is a CAD pic of my room, 17x26 with 10ft walls, and 12" tray ceiling. Speaker placement with one wall removed is shown in the picture. Thanks in advance.


----------



## Dirt9

audiomirage said:


> I was wondering if someone would be willing to give me some advice on sound treatment using the material that I have listed below.
> 
> A friend of mine gave me 13 left over Acoustic Panels from a job he did. ( https://acoufelt.com/product-category/panel/solid/ ) Here is a quick bit of info regarding the panels from thier website:
> _(Acoufelt wall and ceiling panels achieve a minimum NRC of 0.45 and are available in a variety of solid colourways. Panels come in a standard size of 2440 x 1220mm with a thickness of 12 or 24mm. Depending on the acoustic demands of the room, solid panels can be applied to cover the entire wall or ceiling, or as a standalone feature, adding colour and texture to the space.)_
> 
> I plan on cutting the 4x8 panels into Squares, and then stack two or three to make a diamond shape pattern with different colors and sizes. (I have Black, Navy Blue, and Grey).
> 
> Attached is a CAD pic of my room, 17x26 with 10ft walls, and 12" tray ceiling. Speaker placement with one wall removed is shown in the picture. Thanks in advance.


That stuffs to thin to do much of anything by itself.im not a expert but I would useit to face a few 6 inch diy absorbers or incorporate it into a RFZ.I think your idea for wall accents sound really cool also.


----------



## Blackdevil77

I posted this on the previous page, but didn't get any responses. Demo has begun on the room and framing will begin soon. I wan't to incorporate as much of the treatment as possible into the framing, so I'm looking for some input as to where to place treatments in this room. I don't want the room to be overly dead sounding, front wall behind the A/T screen will be all absorption (obviously). For the side walls, I'm assuming treatment at the first reflection points on both sides. Not sure if just absorption or a combo of absorption and diffusion would be ideal for that. Back wall I'm assuming some diffusion. What else should/could I do? Ceiling height is low at 7 feet, but I COULD try and get some treatment in between the joists of the ceiling and use a fabric to cover up the ceiling instead of drywall.

What would you do to treat this room?


----------



## audiomirage

Dirt9 said:


> That stuffs to thin to do much of anything by itself.im not a expert but I would useit to face a few 6 inch diy absorbers or incorporate it into a RFZ.I think your idea for wall accents sound really cool also.


I appreciate the input, but specifications show it does something, depending on installation method, ie. air gap. At a cost of $300 per panel, and the fact that I got them at little to no cost, it is what I have to work with. 

https://acoufelt.com/wp-content/uploads/2018/11/acoufelt-ap12-panel-specifications.pdf


----------



## Dirt9

audiomirage said:


> Dirt9 said:
> 
> 
> 
> That stuffs to thin to do much of anything by itself.im not a expert but I would useit to face a few 6 inch diy absorbers or incorporate it into a RFZ.I think your idea for wall accents sound really cool also.
> 
> 
> 
> I appreciate the input, but specifications show it does something, depending on installation method, ie. air gap. At a cost of $300 per panel,
> and the fact that I got them at little to no cost, it is what I have to work with. 🙂
> 
> https://acoufelt.com/wp-content/uploads/2018/11/acoufelt-ap12-panel-specifications.pdf
Click to expand...

Look up bob gold acoustic website to compare the .25nrc with something similar.


----------



## Scurly

*Need additional acoustical treatment*

Help! See pic below. My builder thought it funny to create a media room with these kinds of 45d angled ceilings. Anyone have these in their dedicated or non-dedicated media room?

I used the mirror trick for the location to hang the panels you see in the pic, but the room still needs more to reduce/eliminate the echo. Here are my questions for experts

1. Can you install too much acoustical treatment in a media room? is there a % of sq ft not to exceed?
2. Where should I install more of these panels (I will be using foam panels due angle and cost) just bought the new pj
3. Can you have gaps between panels?
4. I know there is a science to this, but is it an exact science? Can I just cover most of the 45degree angles and some ceiling?
5. Should I relocate the one panel on back wall?
6. Do I need bass traps? If so, how many? 4 for each wall located high in corners?

Many thanks to anyone’s help here. 

The look of the room will not bother me too much which is why I’m okay with foam pyramids or Wedges. I just want a the echo gone and the best acoustical room possible.


----------



## JonnyVee

JonnyVee said:


> Looking for a little advice. I can only find Comfortboard 80 1.5” locally. I could special order 2”, but it’ll take awhile to come in. So I’m thinking just use 1.5” which means my options are:
> 
> 1. 1.5” 80 in a 2” deep frame (Minimal air gap)
> 2. 1.5” 80 in a 3” deep frame (1.5” air gap)
> 3. Double up the 80 for 3” of insulation in a 3” deep frame (no air gap)
> 
> I really don’t want to go with 4” deep frames as the area is already quite small.
> 
> I’ll be adding on the side wall, back wall and ceiling.


Update in case anyone is interested. 

I doubled up on the 1.5” to get 3” thick in a 3” deep frame and tested that behind the MLP two days ago. Performance-wise it worked too well ... It seemed to suck all the life out of the room. I’m thinking it’s because we’re only a foot from the back wall. 

I then trialed a single 1.5” layer behind the MLP and 3 panels on the side. Very nice results. Takes out the harsh brightness in the room without making it sound dead. I’ll be putting two panels on the ceiling this week as well. 

I know 1.5” is not ideal, but my room is small and 1.5” seems to suit it. I’ll take some measurements later this week or weekend.


----------



## Ccondo1

Full confession, I have not skimmed thru the entire 421 pages of this thread. I was wondering if someone had any suggestions for DIY acoustic treatments and schematics if I'm looking to level up from simple OC703 panels. I'm looking to create more dispersion and less of simply absorbing high frequencies. Any suggestions? Here is an example of a diffusion device. Maybe include something denser than 703 and mix and match to simulate what the pros do?


----------



## Dirt9

Ccondo1 said:


> Full confession, I have not skimmed thru the entire 421 pages of this thread. I was wondering if someone had any suggestions for DIY acoustic treatments and schematics if I'm looking to level up from simple OC703 panels. I'm looking to create more dispersion and less of simply absorbing high frequencies. Any suggestions? Here is an example of a diffusion device. Maybe include something denser than 703 and mix and match to simulate what the pros do?


The easiest thing is to take a 1x4 and cut in down the middle.then screw them on the out side of whatever absorber you make every 3/4" for a 70/30 ratio.


----------



## Scurly

Scurly said:


> Help! See pic below. My builder thought it funny to create a media room with these kinds of 45d angled ceilings. Anyone have these in their dedicated or non-dedicated media room?
> 
> I used the mirror trick for the location to hang the panels you see in the pic, but the room still needs more to reduce/eliminate the echo. Here are my questions for experts
> 
> 1. Can you install too much acoustical treatment in a media room? is there a % of sq ft not to exceed?
> 2. Where should I install more of these panels (I will be using foam panels due angle and cost) just bought the new pj
> 3. Can you have gaps between panels?
> 4. I know there is a science to this, but is it an exact science? Can I just cover most of the 45degree angles and some ceiling?
> 5. Should I relocate the one panel on back wall?
> 6. Do I need bass traps? If so, how many? 4 for each wall located high in corners?
> 
> Many thanks to anyone’s help here.
> 
> The look of the room will not bother me too much which is why I’m okay with foam pyramids or Wedges. I just want a the echo gone and the best acoustical room possible.


Sorry to quote my own post but really needing some advise here based on the pics. Any questions? Tried to provide everything I could but pics should say all. 

*Additional question:* any tricks to hanging panels on a 45 degree angled ceiling? Looking at adding Roxul 60 (7.4 pcf) 1” thick due to the complexity of the angle for weight and safety. Also, hanging same on ceiling 1“ thick for weight savings is


----------



## Dirt9

I would recommend learning rew(room eq wizard)to see how your room measures and research room acuastics heavily.A room your size could easily except 5k worth of acuastic treatment just to get started depending on how far your willing to get into it.
It can be very confusing and definitely challenging but unless you pay someone that's the only way.
Looking at you room and if it was mine I would absorb both side walls floor to ceiling from the first reflection area all the way to the screen wall.Put in a suspended cloud hanging from chaines,a very (large) cloud.
Bass trap all your vertical corners up to where the the wall makes a 45 to start.
Treat the back wall (thick)10" or more.
Then use the thin absorber material you already have to fine tune the eco to your liking.


----------



## Scurly

Dirt9 said:


> I would recommend learning rew(room eq wizard)to see how your room measures and research room acuastics heavily.A room your size could easily except 5k worth of acuastic treatment just to get started depending on how far your willing to get into it.
> It can be very confusing and definitely challenging but unless you pay someone that's the only way.
> Looking at you room and if it was mine I would absorb both side walls floor to ceiling from the first reflection area all the way to the screen wall.Put in a suspended cloud hanging from chaines,a very (large) cloud.
> Bass trap all your vertical corners up to where the the wall makes a 45 to start.
> Treat the back wall (thick)10" or more.
> Then use the thin absorber material you already have to fine tune the eco to your liking.


Dirt, in case this was meant for me....thx for the input and suggestions. I have (in deed) researched until I am blue in the face. I’m more confused than ever and down right sorry I ever got into this hobby...jk of course. 

I’m no sound engineer and most of this room acoustic jargon flies well over my head. the extent of my knowledge is Being able determine reflection points with a mirror, that’s it. I also just parted with a ridiculous amount for a new projector, so the idea of spending 5k just to get started (while probably the right thing to do) will never happen. 

I simply wanted to add to what I have and not screw it up. I primarily wanted to obtain some realistic suggestions on how to treat these ridiculous 45 degree walls/ceilings. I would also love to be able to pay for an acoustical engineer but that isn’t in the budget either. I am also going to have to make these panels myself, which appears to be relatively easy. I’m concerned about hanging panels on a 45 degree wall for safely reasons. Therefore, my first thought was foam...then that idea went away after I heard foam does nothing, so I’m back to thinking ”light” (like 1” thick) panels with zero framing. 

I’m confused and frustrated with no real direction and just do the best I can. That’s why I come to these forums. Thx for advise, although the cost is out of my league I’m afraid.


----------



## JonnyVee

JonnyVee said:


> Update in case anyone is interested.
> 
> I doubled up on the 1.5” to get 3” thick in a 3” deep frame and tested that behind the MLP two days ago. Performance-wise it worked too well ... It seemed to suck all the life out of the room. I’m thinking it’s because we’re only a foot from the back wall.
> 
> I then trialed a single 1.5” layer behind the MLP and 3 panels on the side. Very nice results. Takes out the harsh brightness in the room without making it sound dead. I’ll be putting two panels on the ceiling this week as well.
> 
> I know 1.5” is not ideal, but my room is small and 1.5” seems to suit it. I’ll take some measurements later this week or weekend.


Here’s a shot of the room.


----------



## Dirt9

JonnyVee said:


> JonnyVee said:
> 
> 
> 
> Update in case anyone is interested.
> 
> I doubled up on the 1.5â€ to get 3â€ thick in a 3â€ deep frame and tested that behind the MLP two days ago. Performance-wise it worked too well ... It seemed to suck all the life out of the room. Iâ€™️m thinking itâ€™️s because weâ€™️re only a foot from the back wall.
> 
> I then trialed a single 1.5â€ layer behind the MLP and 3 panels on the side. Very nice results. Takes out the harsh brightness in the room without making it sound dead. Iâ€™️ll be putting two panels on the ceiling this week as well.
> 
> I know 1.5â€ is not ideal, but my room is small and 1.5â€ seems to suit it. Iâ€™️ll take some measurements later this week or weekend.
> 
> 
> 
> Hereâ€™️s a shot of the room.
Click to expand...

Hey that looks like a nice space.how does it measure?


----------



## JonnyVee

Dirt9 said:


> Hey that looks like a nice space.how does it measure?


Before 










After ...


----------



## Darthprater

For those of you have used black velvet to cover your absorption panels, do you notice anything detrimental in particular maybe vs. using an acoustically transparent fabric? I am going to have quite a bit of leftover black velvet from covering the walls with it...and I’d like to use it if I can, to make use of it but mainly because I want to keep the room as black-hole black as possible in front of the seating area. Thanks. 


Sent from my iPhone using Tapatalk


----------



## uberbimmer

is no one here concerned about mineral wool or fiberglass fibers escaping through the covering material? 



im kind of paranoid about my family breathing in potentially toxic materials every time the bass shakes the walls


----------



## AndreNewman

uberbimmer said:


> is no one here concerned about mineral wool or fiberglass fibers escaping through the covering material?
> 
> 
> 
> im kind of paranoid about my family breathing in potentially toxic materials every time the bass shakes the walls




No sign of anything escaping here, we are both quite sensitive to anything in the air. There were a few particles around while I was assembling our bass traps even though all the cutting was done outside. Since they were installed, nothing, I think if anything escaped it would be obvious against the velvet which looks pristine still 6 months on.


----------



## uberbimmer

AndreNewman said:


> No sign of anything escaping here, we are both quite sensitive to anything in the air. There were a few particles around while I was assembling our bass traps even though all the cutting was done outside. Since they were installed, nothing, I think if anything escaped it would be obvious against the velvet which looks pristine still 6 months on.



im more concerned with the particles that may not be visible.


did you cover your panels in velvet or you just have velvet in the room?


----------



## wookiegr

I read somewhere that your lungs can safely absorb mineral wool fibers and they break down in your body as opposed to fiber glass which can damage your lungs. I assume anyone using a fiber glass based sound absorption system in their theater space would use an air filter or purifier in the room every so often. I use to have a honeywell air purifier on my apartment while waiting for my house to be built and that thing got dirty after only a couple weeks of running and we are not smokers or candle burners. I can only imagine what you don't see in the air when subwoofers are wreaking havoc on the space.


----------



## Hawks07

Hello, I'm looking for help on placing an absorption panel. One of my first reflection points on my side wall is a French door for the main entry. I don't want to drill holes in the door and was looking for a solution. I was looking at 4" foam panels from ATS that would be easy to install and was wondering if those would work well or if there were other solutions.
Thanks for any help.


----------



## AndreNewman

uberbimmer said:


> im more concerned with the particles that may not be visible.
> 
> 
> did you cover your panels in velvet or you just have velvet in the room?




I Used whaleys velvet to cover the visible front sides of four bass traps. The only other velvet in the room is the curtains.

I’m planning to get an air filter with some air quality sensing fairly soon so might be able to get some sort of measurements then. I’m more concerned with the chemical smell off the curtains than anything escaping from the bass traps.

I think it’s possible to add a thin layer of foam between the mineral wool and the velvet without affecting the audio response, maybe that could be a solution?

Pure bass traps (not broadband absorbers) often have a plastic layer on top of the mineral wool, that should prevent anything escaping. I don’t know exactly what material is suitable and I wanted broadband absorption so I didn’t do that.


----------



## Hawks07

Hello, I have a quick question. 
I will be installing GIK 242 panels on my rear wall for broadband absorption. My MLP is about 9' from the rear wall. Would I benefit by adding an additional air gap between the panel and wall? If so, how thick of an air gap? I know some people do 2" or 4". 
Thanks for any help.


----------



## uberbimmer

AndreNewman said:


> I Used whaleys velvet to cover the visible front sides of four bass traps. The only other velvet in the room is the curtains.
> 
> I’m planning to get an air filter with some air quality sensing fairly soon so might be able to get some sort of measurements then. I’m more concerned with the chemical smell off the curtains than anything escaping from the bass traps.
> 
> I think it’s possible to add a thin layer of foam between the mineral wool and the velvet without affecting the audio response, maybe that could be a solution?
> 
> Pure bass traps (not broadband absorbers) often have a plastic layer on top of the mineral wool, that should prevent anything escaping. I don’t know exactly what material is suitable and I wanted broadband absorption so I didn’t do that.



how are you using velvet to cover your panels when velvet isnt acoustically transparent?


----------



## AndreNewman

uberbimmer said:


> how are you using velvet to cover your panels when velvet isnt acoustically transparent?


I did some tests with the velvet I bought and it's acoustically transparent enough for me.
I did a REW sweep of my center speaker, then again with the velvet laid across the speaker, there's a visible and audible effect but it's not huge.

The velvet is just pulled tight and stapled to the wooden frame, I have some cheap black cotton sheets I bought on Amazon covering the back of the panels or traps and the velvet on the visible sides.

Here's the with and without sweep:


----------



## jeffreynmandy

I'm wanting absorption with a consideration on looks. I've come up with this design instead of a plain flat side box. It will have 2.5" of 703 with a 0.5" air gap. I was going to drill 2.5" holes or cut a wide slot into the sides but I found an article from gik that states the difference wouldn't be that great. Maybe the angled sides can act as a scatter/diffuser.

I'm going to cover them in speaker cloth since I'm going with black on the color. I removed the 703 from office panels. 


Would the extra work be worth it putting holes into the sides before I cover them? It will double the time involved and I have 14, 24x24" and 8, 24x48" to make.




















GIK article. - https://www.gikacoustics.com/diy-acoustic-panel-frames/


----------



## Blackdevil77

What is better to treat the front wall of a home theater with.

This stuff 

https://www.jm.com/en/hvac/duct-lin...uj5h6DLKrqSP02CIL-ry420zdxIhEx9fWlBKRJG8NS5z0

Or this stuff

https://www.buyinsulationproductstore.com/4-thick-4-mineral-wool-acoustical-board/


----------



## pkinneb

Blackdevil77 said:


> What is better to treat the front wall of a home theater with.
> 
> This stuff
> 
> https://www.jm.com/en/hvac/duct-lin...uj5h6DLKrqSP02CIL-ry420zdxIhEx9fWlBKRJG8NS5z0
> 
> Or this stuff
> 
> https://www.buyinsulationproductstore.com/4-thick-4-mineral-wool-acoustical-board/


2 layers of 1" Linacoustic RC with a layer of 3 mil plastic in between seems to be the go too


----------



## Blackdevil77

pkinneb said:


> 2 layers of 1" Linacoustic RC with a layer of 3 mil plastic in between seems to be the go to


Yes, the Linacoustic stuff was recommended to me, then I came across that mineral wool stuff. Seems to absorb more lower frequencies which should be more effective in combating stuff like SBIR, no? Why only 2 layers of 1"? Is 4" of the stuff too much?


----------



## Blackdevil77

Blackdevil77 said:


> What is better to treat the front wall of a home theater with.
> 
> This stuff
> 
> https://www.jm.com/en/hvac/duct-lin...uj5h6DLKrqSP02CIL-ry420zdxIhEx9fWlBKRJG8NS5z0
> 
> Or this stuff
> 
> https://www.buyinsulationproductstore.com/4-thick-4-mineral-wool-acoustical-board/


 @BIGmouthinDC What do you think? Which material would be better for front wall treatment? I appears as though the mineral wool absorbs more low frequency.


----------



## C J

I want to experiment with some treatment panels behind my couch that sits against the wall. My room is about 18x18 ft with 8ft ceilings. I am looking at placing four sound absorption panels behind them or four diffusion panels or two of each. My room also has concrete floors.


diffuser
https://ua-acoustics.com/sound-diffuser/Sirius


panel
https://www.amazon.com/Absorption-D...r&qid=1582653517&s=musical-instruments&sr=1-7


which would work better?
room pic below


----------



## ereed

C J said:


> I want to experiment with some treatment panels behind my couch that sits against the wall. My room is about 18x18 ft with 8ft ceilings. I am looking at placing four sound absorption panels behind them or four diffusion panels or two of each. My room also has concrete floors.
> 
> 
> diffuser
> https://ua-acoustics.com/sound-diffuser/Sirius
> 
> 
> panel
> https://www.amazon.com/Absorption-D...r&qid=1582653517&s=musical-instruments&sr=1-7
> 
> 
> which would work better?
> room pic below


With your couch up against the rear wall you want broadband absorption, not diffusion which requires you to be further way from the wall.


----------



## Harddrive2

jeffreynmandy said:


> I'm wanting absorption with a consideration on looks. I've come up with this design instead of a plain flat side box. It will have 2.5" of 703 with a 0.5" air gap. I was going to drill 2.5" holes or cut a wide slot into the sides but I found an article from gik that states the difference wouldn't be that great. Maybe the angled sides can act as a scatter/diffuser.
> 
> I'm going to cover them in speaker cloth since I'm going with black on the color. I removed the 703 from office panels.
> 
> 
> Would the extra work be worth it putting holes into the sides before I cover them? It will double the time involved and I have 14, 24x24" and 8, 24x48" to make.
> 
> 
> GIK article. - https://www.gikacoustics.com/diy-acoustic-panel-frames/


I read that same article and decided holes/slots in the side of the frame don't provide enough benefit to be worth the investment of the time it takes to make them. The angled frame looks great, but won't do a whole lot for diffusion. Since the angle is constant across the width of the frame, it will act as a reflector (waves hitting different locations on the frame are all scattered at more or less at the same angle). If you want it to be a diffuser you should round the side of the frame so that sound hitting different locations on the frame are scattered in different directions.

Regards,
Steve


----------



## Hawks07

I am just checking to see what panels if any are recommended on the rear side walls behind the MLP.
I have two rows of seating with the second row on a riser. I have placed panels on the contra lateral spots in front of the first row and more broadband absorption on the rear wall.
The second row isn't used much do I don't know if placing more panels on the side walls behind the first row would help.
I've read that you don't want want the area too dead behind you so just checking what might be recommended there.
Any help would be great. Thanks.


----------



## jeffreynmandy

Do these types of diffusers actually do anything or are they mostly for looks?










I came across these at a habitat for humanity store for $1 a pack. They could make great lightweight diffusers.


----------



## Hawks07

Hawks07 said:


> I am just checking to see what panels if any are recommended on the rear side walls behind the MLP.
> I have two rows of seating with the second row on a riser. I have placed panels on the contra lateral spots in front of the first row and more broadband absorption on the rear wall.
> The second row isn't used much do I don't know if placing more panels on the side walls behind the first row would help.
> I've read that you don't want want the area too dead behind you so just checking what might be recommended there.
> Any help would be great. Thanks.


So to add to my previous question. I was going to install 3 broadband 4" absorbers across my rear wall. I know a lot of people are adding diffusers to the back wall.
Should I maybe add diffusers to the back wall along with the 4" panels or even the back side walls?
I was also looking at the GIK Impression panels which are a combination absorber/diffuser/bass panels as opposed to just the normal 4" panels.
Here is a picture of the rear of my theater. Any suggestions would be great.


----------



## harrisu

Hi guys,
Does anyone know how to make a broad band panel reflect higher frequencies? I have heard that using FRK paper with its shiny side facing would reflect high frequency? https://www.buyinsulationproductstore.com/frk-paper-pack-of-12-sheets/


----------



## ereed

Hawks07 said:


> So to add to my previous question. I was going to install 3 broadband 4" absorbers across my rear wall. I know a lot of people are adding diffusers to the back wall.
> Should I maybe add diffusers to the back wall along with the 4" panels or even the back side walls?
> I was also looking at the GIK Impression panels which are a combination absorber/diffuser/bass panels as opposed to just the normal 4" panels.
> Here is a picture of the rear of my theater. Any suggestions would be great.


If you like the design or shapes of the Impression series then get it. If you want a better diffuser/absorber panel then get the Alpha series. If you can go 6 inches, that will give you more low end absorption. If you want something similar to the Alpha series but not a fan of the slats look and want all fabric look then look at the 244 or monster panels with scatter plates installed. Basically same thing depending on how you want your room to look.


----------



## Hawks07

ereed said:


> If you like the design or shapes of the Impression series then get it. If you want a better diffuser/absorber panel then get the Alpha series. If you can go 6 inches, that will give you more low end absorption. If you want something similar to the Alpha series but not a fan of the slats look and want all fabric look then look at the 244 or monster panels with scatter plates installed. Basically same thing depending on how you want your room to look.


Thanks for the input. Yeah looks are not that important so maybe the Alpha would be better. 
However I already have some 4" broadband panels I was looking to possibly re purpose. if I did just end up installing the 4" panels in the back would it be a good idea to add diffusers on either side of those? I know GIK also has just diffusers as well, so didn't know if that would be the same without the bass trapping.
Thanks again.


----------



## ereed

Hawks07 said:


> Thanks for the input. Yeah looks are not that important so maybe the Alpha would be better.
> However I already have some 4" broadband panels I was looking to possibly re purpose. if I did just end up installing the 4" panels in the back would it be a good idea to add diffusers on either side of those? I know GIK also has just diffusers as well, so didn't know if that would be the same without the bass trapping.
> Thanks again.


Depends on what the 4 inch panels are....not all 4 inch panels are created equal. If they are anything similar to GIK 244 full range you could put those on middle rear wall and do alpha 4a on the sides next to it. Or you can use the 4 inch on first reflection points. You have to test it and see what you like and see what your RT60 feels like. The most important is corner bass traps IMO. Then rear wall and of course side wall reflections if you decide to treat those.

Or you can use your 4 inch behind your mains to combat sbir issues.


----------



## Hawks07

ereed said:


> Depends on what the 4 inch panels are....not all 4 inch panels are created equal. If they are anything similar to GIK 244 full range you could put those on middle rear wall and do alpha 4a on the sides next to it. Or you can use the 4 inch on first reflection points. You have to test it and see what you like and see what your RT60 feels like. The most important is corner bass traps IMO. Then rear wall and of course side wall reflections if you decide to treat those.
> 
> Or you can use your 4 inch behind your mains to combat sbir issues.


Thanks again for your help. The 4" panels are ATS panels, I don't know how they compare to the 244s. I compared them to the 242s and these looked like they tested better.
I was going to buy two more of the ATS panels to replace my current 2" panels that I have on my contra lateral reflection points up front. I guess I could use 2 4" panels that I currently have and either sell or repurpose that other one somewhere, maybe rear ceiling. 
I guess it would come down to what is better, 3 4" panels with the 2 4as or 3 6as on the rear.
Thanks again for your time.


----------



## Hawks07

So I think I am going to go ahead and get three Gik Alpha 6s for my rear wall. I am going to repurpose one of my 4" panels for a side reflection spot which will leave me with 2 extra 4" panels.
Does anybody have any good suggestions on where to put the extra 4" panels?
Maybe rear side walls, on the back wall with the 3 Alphas or ceilings? Or would that make the rear too dead?


----------



## wookiegr

Doesn't seem there is a good solution for completely blacked out sound panels that compliment a black void theater. You go though all the effort to use Black Rosco TV paint to eliminate light reflections and use tons of triple black velvet everywhere then your DIY sound panels with burlap or some printed artwork goes and messes up the light control to a minor degree. Is there no best solution for creating a completely integrated blacked out sound dampening system since velvet is not acoustically transparent? Going back and forth between threads on sound control and blackened theater it seems there is either one camp or the other but none regarding a way to merge them both.


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## Darthprater

wookiegr said:


> Doesn't seem there is a good solution for completely blacked out sound panels that compliment a black void theater. You go though all the effort to use Black Rosco TV paint to eliminate light reflections and use tons of triple black velvet everywhere then your DIY sound panels with burlap or some printed artwork goes and messes up the light control to a minor degree. Is there no best solution for creating a completely integrated blacked out sound dampening system since velvet is not acoustically transparent? Going back and forth between threads on sound control and blackened theater it seems there is either one camp or the other but none regarding a way to merge them both.




Well said. I’m in the exact same spot as you; I’d like to have some kind of verification that the velvet would or wouldn’t work fine. I’m kind of wondering that if the wood framing is made just slightly less thick than the insulation on the panels (to where the insulation sticks out maybe 1/4” or less), and the velvet is press tightly against the insulation, if it would prevent any worry of resonance on the black velvet at higher frequencies and therefore eliminate any reflections off of the panels. Just a thought to throw into the mix. 


Sent from my iPhone using Tapatalk


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## OJ Bartley

I think the velvet will reflect more than a specifically acoustically transparent material like GOM or grille cloth, but I would think it still does a good job for room treatment panels. I wouldn't use velvet in front of speakers, because that will have a significant effect on the sound, but I don't think it would matter as much on a panel. I would guess that the panel would be a little more reflective in the high frequencies, but the only way to know for sure is to measure. If you have a very specifically calibrated and targeted treatment plan you would want to be sure. If your approach is more general or broadband I doubt you would notice much of a difference.

Edit - I'm not an expert, and every fabric will vary slightly with tightness of weave, thickness, etc. Always best to measure first or use a known product to be sure.


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## dead2sin

*Acoustic panel placement advice?*

Hey all! I'm looking at adding acoustic panels to my basement theater/multipurpose room. I believe I have an idea of where to place the speakers, but I wanted to post and see if anyone had suggestions for me. Attached are photos with the locations I was thinking of, happy to get feedback. 



The entire side of this is rather open, so I'm not sure how to account for that (There is a bar and open space for VR usage).


Thanks,


Nate


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## sdurani

dead2sin said:


> The entire side of this is rather open, so I'm not sure how to account for that (There is a bar and open space for VR usage).


Gotta pic of the "rather open" side? To restore symmetry, I would look at any open area on the left side wall and mimic it with absorbers on the right side wall.


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## dead2sin

sdurani said:


> Gotta pic of the "rather open" side? To restore symmetry, I would look at any open area on the left side wall and mimic it with absorbers on the right side wall.



I think that is impossible to do, but here is what I have: (Excuse the mess...3 kids mean my theater is never clean  )


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## sdurani

No pic.


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## dead2sin

sdurani said:


> No pic.



Upload didn't work. Lemme try again.


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## sdurani

OK, the other wall is just farther away. The earlier pic of the right side wall shows that you were willing to place 4 panels there. That would be a good start. Don't need as much on the back wall, maybe a couple panels directly opposite the centre speaker.


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## dead2sin

sdurani said:


> OK, the other wall is just farther away. The earlier pic of the right side wall shows that you were willing to place 4 panels there. That would be a good start. Don't need as much on the back wall, maybe a couple panels directly opposite the centre speaker.



Got it. So blocking as much sound as I can at the front, plus a few panels on the side and one in the back should cover it for now?


Thanks!


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## sdurani

Yes, the side wall panels will keep the front soundstage from appearing lopsided.


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## dead2sin

sdurani said:


> Yes, the side wall panels will keep the front soundstage from appearing lopsided.



Oh yea, should 2" corning 703 be sufficient? I assume 1" won't absorb enough.


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## sdurani

2" will absorb mostly mids and highs. Like using a tone control to turn down the treble. 

4" would be better. OR, place the 2" panel a couple inches off the wall (the air gap will help).


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## Scurly

*Panel hardware advice*

1. Need some advice on mounting several 2’x4’x2” framed panels on a 45 degree angled ceiling. 

2. Need some advice on hanging same size panels on the ceiling itself. The FRP is right above the ceiling fan. You can barely see from pic (blue small tape piece) but there is room to mount the panel flush against the ceiling with room to clear the ceiling fan. 

Could I use a set of long (30” or so) Z-clips for both above scenarios above? Any advice?


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## roxiedog13

*Need acoustic black velvet and acoustic fabric to make panelsfor*

I'm just getting to the acoustic finishing for my theater build, will need acoustic black velvet , various colors of grey acoustic material to make wall panels and I'll need some speaker grill material as well . Looking for a one stop shop if I can
to place a rather large order of fabrics.


I'm in Canada, would prefer to source locally if I can in light of what is going on, however, any source will be helpful at this point . 



Cheers


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## Mr_Hifi

What are your thoughts of this; No room treatments needed. Reflective walls and trusting in a good room correction system. Marketing or is there something behind these claims that i have missed as people often recommend some room treatments? Please read the first post and comment. Thanks!

https://www.avforums.com/threads/room-treatment-–-this-years-snake-oil.2280627/


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## roxiedog13

*Do I need acoustic panels if walls covered with velvet fabric*



Mr_Hifi said:


> What are your thoughts of this; No room treatments needed. Reflective walls and trusting in a good room correction system. Marketing or is there something behind these claims that i have missed as people often recommend some room treatments? Please read the first post and comment. Thanks!
> 
> https://www.avforums.com/threads/room-treatment-–-this-years-snake-oil.2280627/



Well, this is exactly where I was headed to be honest, the article certainly helpful and timely, thank you. My theater will have panels covering all walls and sloped ceilings , above the soffit I'm using a fabric star dome using acoustic fabric. At first I was sourcing acoustically transparent fabrics to wrap the panels, now I'm considering just using triple black velvet on these same panels which already possesses substantial sound attenuation. The columns and soffit only will be exposed, being made from MDF they will reflect sound efficiently however the total surface area of all columns and soffit only amount to 20% of surfaces, 80% would be covered with a plushy black velvet material . The room is built theater specific as a full floating room , all joists and beams decoupled. Walls are double sheetroc 5/8" , hung on hangers and rails with generous amounts of green glue . Double sealed door entrance, etc., etc..


Question is: Do I really need to add acoustic absorption to panels using acoustically transparent fabric, or will triple black velvet panels covering 80% of the walls suffice???? According to the thread link info you posted, I should be just fine, in fact ,more than just fine, I believe it will be great, or at the very least quite sufficient . Oh and to add, I have a Stormaudio 3D ISP.32 processor with Dirac room correction and Dirac bass management . Considering all this , I'm guessing I will do just fine. 


Hoping to hear some comments from the acoustic/soundproofing gurus . I would actually have the best of both worlds if I could source Devore black velvet which is acoustically transparent, but because of the Pandemic they are shut down. I have a crew working on my theater now, they will need the fabrics within a couple weeks to continue . 


All comments and suggestions welcome, thank you in advance.


Robert


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## Mashie Saldana

roxiedog13 said:


> Well, this is exactly where I was headed to be honest, the article certainly helpful and timely, thank you. My theater will have panels covering all walls and sloped ceilings , above the soffit I'm using a fabric star dome using acoustic fabric. At first I was sourcing acoustically transparent fabrics to wrap the panels, now I'm considering just using triple black velvet on these same panels which already possesses substantial sound attenuation. The columns and soffit only will be exposed, being made from MDF they will reflect sound efficiently however the total surface area of all columns and soffit only amount to 20% of surfaces, 80% would be covered with a plushy black velvet material . The room is built theater specific as a full floating room , all joists and beams decoupled. Walls are double sheetroc 5/8" , hung on hangers and rails with generous amounts of green glue . Double sealed door entrance, etc., etc..
> 
> 
> Question is: Do I really need to add acoustic absorption to panels using acoustically transparent fabric, or will triple black velvet panels covering 80% of the walls suffice???? According to the thread link info you posted, I should be just fine, in fact ,more than just fine, I believe it will be great, or at the very least quite sufficient . Oh and to add, I have a Stormaudio 3D ISP.32 processor with Dirac room correction and Dirac bass management . Considering all this , I'm guessing I will do just fine.
> 
> 
> Hoping to hear some comments from the acoustic/soundproofing gurus . I would actually have the best of both worlds if I could source Devore black velvet which is acoustically transparent, but because of the Pandemic they are shut down. I have a crew working on my theater now, they will need the fabrics within a couple weeks to continue .
> 
> 
> All comments and suggestions welcome, thank you in advance.
> 
> 
> Robert


That article is just a very nice sales pitch trying to justify extremely expensive audio gear.

I suggest you take a look at the Rob Hanh theatre if you think room treatment isn't needed. It is considered the best HT in existance and it has a foot worth of treament on every wall/ceiling an addition to room correction applied.


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## roxiedog13

Mashie Saldana said:


> That article is just a very nice sales pitch trying to justify extremely expensive audio gear.
> 
> I suggest you take a look at the Rob Hanh theatre if you think room treatment isn't needed. It is considered the best HT in existance and it has a foot worth of treament on every wall/ceiling an addition to room correction applied.



Thanks for the link . Unfortunately you misunderstood , I did not say room treatment is not needed , insufficient room treatments is just as much wrong as using too much treatment . Creating a dead room anechoic chamber is also not ideal for home theater. If you have a theater with carpet, soft furniture, 90% of the walls covered in thick plush velvet, a treated screen wall and fabric dome acoustic ceiling as I do, I'd hazard a guess it will be pretty neutral acoustically. That said I still intend to add acoustic absorption where necessary, combined with sound deadening products to correct is the desired approach. 


Black velvet has a NRC rating of .6, Rockwool 1" absorption panels rated exactly the same. I'd expect descent results covering all open walls with any material having a rating of .6 NRC , but I'll certainly improve on this without a doubt.


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## Mashie Saldana

roxiedog13 said:


> That said I still intend to add acoustic absorption where necessary, combined with sound deadening products to correct is the desired approach.


A layer of absorption everywhere is a legacy design. Modern ones are more 50/50 absorption/diffusion at the first reflection points and the absorption should really be 2" or preferably 4" thick and even thicker bass traps if possible.


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## Ignorant

*Advice*

A little advice please, I have 2" Lineacoustic on the front wall, planning 1" OC703 for the inserts in the wainscoting below ear level and poly batting above the wainscoting. Any issues with this plan?


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## roxiedog13

Mashie Saldana said:


> A layer of absorption everywhere is a legacy design. Modern ones are more 50/50 absorption/diffusion at the first reflection points and the absorption should really be 2" or preferably 4" thick and even thicker bass traps if possible.



Thanks for the clarification .I did not make provisions for 2" of absorption all around , that was never really considered . I will get a full 4" around the bottom up to the top of the knee wall five feet high. On the sloped wall up to the soffit I can get 1-1.5" of material. Above the soffit and up to the peek I can place 4" of material behind the star ceiling fabric dome. Combined with carpet and soft furniture, hoping the results will be acceptable. At least I know what I should aim for, will try to make the grade by choosing the best acoustic materials available. My room is far from an ideal shape acoustically, I'm trying to make the best of a sloped ceiling space I have to work with . I guess in my case, a legacy design with plenty of absorption would be the best approach. Bottom line, I'll place as much absorption as is possible, the 50/50 approach in my less than ideal room shape is likely the wrong approach . 


Now I have a question since you appear to be well versed with acoustics. I made a knee wall that runs the length of my theater both sides. I can do one of two things. I can just cover the face of the knee wall panels with acoustically transparent material and line the inside of the knee wall space with 4" acoustic material. Alternatively I can place 2" of absorption in the knee wall panels, I'll still place carpet and acoustic absorption inside. Is there any reason one would be a better approach? 


A couple of reference pictures attached, first a 3D render, second is where I am as of today.


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## Mashie Saldana

roxiedog13 said:


> Thanks for the clarification .I did not make provisions for 2" of absorption all around , that was never really considered . I will get a full 4" around the bottom up to the top of the knee wall five feet high. On the sloped wall up to the soffit I can get 1-1.5" of material. Above the soffit and up to the peek I can place 4" of material behind the star ceiling fabric dome. Combined with carpet and soft furniture, hoping the results will be acceptable. At least I know what I should aim for, will try to make the grade by choosing the best acoustic materials available. My room is far from an ideal shape acoustically, I'm trying to make the best of a sloped ceiling space I have to work with . I guess in my case, a legacy design with plenty of absorption would be the best approach. Bottom line, I'll place as much absorption as is possible, the 50/50 approach in my less than ideal room shape is likely the wrong approach .
> 
> 
> Now I have a question since you appear to be well versed with acoustics. I made a knee wall that runs the length of my theater both sides. I can do one of two things. I can just cover the face of the knee wall panels with acoustically transparent material and line the inside of the knee wall space with 4" acoustic material. Alternatively I can place 2" of absorption in the knee wall panels, I'll still place carpet and acoustic absorption inside. Is there any reason one would be a better approach?
> 
> 
> A couple of reference pictures attached, first a 3D render, second is where I am as of today.


Where are you planning on doing the bass trapping? The knee wall could be good for this if you can go thicker than 4".


This is the current status of my room. The soffit is a 12"x24" bass trap, the ceiling treatment is 2" absorption, as are the walls:











I'm still working on the diffusion for the walls but to give you an idea it will be pretty much like this on the wall in the picture above once done:


----------



## roxiedog13

Mashie Saldana said:


> Where are you planning on doing the bass trapping? The knee wall could be good for this if you can go thicker than 4".
> 
> 
> This is the current status of my room. The soffit is a 12"x24" bass trap, the ceiling treatment is 2" absorption, as are the walls:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I'm still working on the diffusion for the walls but to give you an idea it will be pretty much like this on the wall in the picture above once done:



I can put any thickness of material inside the knee wall, the panels that will cover the same can only hold 1" of insulation. What I could do is just use acoustically transparent material on the panels, place the insulation for the base trap inside the knee wall space. 
I can put one foot or more of material at the back of this space without issue, although I may have a few spots where this is limited to only 4". How about above my soffit at the peak of my roof ? It's about 3 ft wide there, I could easily place another foot or two of material at this high point. The star ceiling fabric will pass most frequencies, I'd expect this would help. My soffit and the columns are made from 3/4" MDF, which is a really dense composite wood as found in speakers. I cannot place anything on those surfaces
without messing with the aesthetics , although, if I have to I will . It only represents 10% or less of the total surface area, and it will be covered with a black velvet material with a .6 NCR rating. 


Once again, really appreciate your help here. 


Robert


----------



## Mashie Saldana

roxiedog13 said:


> I can put any thickness of material inside the knee wall, the panels that will cover the same can only hold 1" of insulation. What I could do is just use acoustically transparent material on the panels, place the insulation for the base trap inside the knee wall space.
> I can put one foot or more of material at the back of this space without issue, although I may have a few spots where this is limited to only 4". How about above my soffit at the peak of my roof ? It's about 3 ft wide there, I could easily place another foot or two of material at this high point. The star ceiling fabric will pass most frequencies, I'd expect this would help. My soffit and the columns are made from 3/4" MDF, which is a really dense composite wood as found in speakers. I cannot place anything on those surfaces
> without messing with the aesthetics , although, if I have to I will . It only represents 10% or less of the total surface area, and it will be covered with a black velvet material with a .6 NCR rating.
> 
> 
> Once again, really appreciate your help here.
> 
> 
> Robert


I would go with 1ft of low density fibreglass insulation at the ceiling and at the knee walls then. Don't cover your MDF features, it is plenty to do the space in between.

Check the link in my signature for how I installed the insulation so it doesn't sag over time.

Make your fabric panels at the sloping parts of the walls removable, that way you can easily add treatment there at a later stage if you think it is required. I wouldn't do that from the start though.


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## knappster007

Quick DIY superchunk bass trap question: 

I'm building corner bass traps, and have two triangular 'shelves at the 1/3 and 2/3 point up the wall to help stack the Sound n' Safe Rockwool. Do I need to drill large (2") holes or slots in these 'shelves' for sound waves to pass through or just leave them solid? I don't want to create some kind of resonant chamber by closing them off, but don't want to waste time if it doesn't matter that they are stuffed with insulation.

Thoughts and suggestions welcome.


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## lax01

I just picked up these acoustic tiles from Amazon to place behind the center channel in hopes I could kill some reflections (center has a back firing port as well) 

Any guidance on which way I should place them? Should the ridges be horizontal or vertical or does it not matter?

Thanks!


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## lax01

First attempt - open to feedback:


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## Mocs123

Does anyone have experience with using acoustic curtains on the wall for absorption instead of acoustic panels with OC703 (or similar)? I had never thought a curtain could absorb very much sound (especially lower frequencies) but the specs seem to do better than 2" OC703 especially at the lower frequencies. 

https://www.rosebrand.com/product1210/32-oz-Magic-Velour-FR.aspx?tid=2&info=acoustic%2bc


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## HopefulFred

Mocs123 said:


> Does anyone have experience with using acoustic curtains on the wall for absorption instead of acoustic panels with OC703 (or similar)? I had never thought a curtain could absorb very much sound (especially lower frequencies) but the specs seem to do better than 2" OC703 especially at the lower frequencies.


I don't have any experience with this, but I would caution anyone to read the fine print on these tests. First, the curtain was hung 4" from the wall. Second, the test method was the reverberation method (I have no idea if that's how all other materials are tested, but I know it's not the only possible test method). Third, the test uses 2 panels.


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## Mocs123

I saw that the curtain was 4" away from the wall, but I didn't see where it uses 2 panels. Does it state somewhere that this fabric was doubled up?

I also didn't know there were different test methods so I might not be comparing apples to apples.


If something is too good to be true it normally is.


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## rcsauvag

Mashie Saldana said:


> This is the current status of my room. The soffit is a 12"x24" bass trap, the ceiling treatment is 2" absorption, as are the walls:


 I have GIK panels I need to hang on my ceiling. They came with toggle bolts, but I'm reluctant to use those as I'd have to make big hole in the ceiling to push them through, which would put holes into my sound isolation plan.

What are you using on the ceiling here? I see the wire going into a silver thing, but not sure what that's called? If you get a bass heavy scene do they move around a bit?


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## HopefulFred

Mocs123 said:


> I saw that the curtain was 4" away from the wall, but I didn't see where it uses 2 panels.


The dimensions of the test material are given. IIRC, they say it's 108" wide and a single panel is 54".


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## Mashie Saldana

rcsauvag said:


> What are you using on the ceiling here? I see the wire going into a silver thing, but not sure what that's called? If you get a bass heavy scene do they move around a bit?


I use 36 of these: https://www.sign-holders.co.uk/hang...linder-ceiling-hanging-fitting-with-hook.html

Not cheap but totally worth it and dead easy to adjust.


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## Mocs123

After several years of being without a theater, I built version 3 of my theater last summer and got the theater functional, but time constraints and budget over-runs prevented me from putting the finishing touches on like acoustical treatments, and I believe it’s time to remedy that situation. I’m looking for advice on how many panels to purchase and where to hang them.

Let’s start by telling you about my room. The room is 16’x21’x8’ with luxury vinyl plank floor over concrete. Walls are double 5/8” heavyweight drywall with rockwool insulation and the ceiling is 5/8” drywall with pink fiberglass insulation above. 

The room has the screen mounted 27” away from the front wall and a “false wall” with the L/C/R and four subs behind the screen. The room has a two-row configuration with three seats in each row and the second row on a 12” riser. The surround and rear-surround speakers are in-wall speakers, and the four Atmos speakers are in-ceiling speakers. I have two layers of Linacoustic duct liner floor to ceiling behind the screen wall that wraps around the corners approximately 18”.

I have 21 Auralex Minifusers for diffusion that are currently unmounted (and unpainted!). I can use them in any configuration, but I was thinking of making a three foot tall and seven foot wide panel with them and mounting it above the rear seats on the back wall, but can use them in another configuration if it treats the room better. 

My initial thoughts are in addition to the Minifusers on the rear wall to put Acoustimac absorption panels on the walls – I was thinking four – 2’x4’x2” panels on each side wall as well as a couple of 2’x4’ panels on the ceiling. I have attached a sketch of my planned layout, does that look OK or are there things that I could do to differently to increase effectiveness? Should I make any of the panels 4” bass traps rather than 2” panels? If so which ones? My OCD for symmetry says maybe the ceiling mounted panels but that might not be best. 

Also, I am thinking of going with Acoustimac’s Eco-Core insulation as they say it outperforms Roxul or OC703 – Does anyone have any experience with it? Also, my room is a dark gray and I am thinking of going with black panels. Is there any advantage between any of their three fabric options (DMD, Executive, and Suede)?

I've attached some pictures of the room (I hadn't finished the black velvet side panels around the screen when I took these pictures - it's complete now).

Thank you so much for your help as I work through the last few touches of my Home Theater!


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## mtbdudex

Mocs123;
What speakers are you using behind the screen? Are they controlled waveguides by chance?

That will affect your side wall treatment strategy and placement.

Also, are you meeting the minimum spacing / degrees for the R and L?
If not, you’d be better off putting them outside the screen.

I’m sure you’ve studied this;









Sent from my iPhone 11Pro using Tapatalk


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## Mocs123

mtbdudex said:


> Mocs123;
> What speakers are you using behind the screen? Are they controlled waveguides by chance?
> 
> That will affect your side wall treatment strategy and placement.
> 
> Also, are you meeting the minimum spacing / degrees for the R and L?
> If not, you’d be better off putting them outside the screen.
> 
> Sent from my iPhone 11Pro using Tapatalk



Thank you for your response!



My L/C/R speakers do have waveguides being JBL Studio 530's (picture attached) Currently they're towed in a little as well. 



Looking at my calculations from when I built the theater I'm 110" between the left and right speakers (center to center) and have a 23.8% angle from the MLP.


----------



## mtbdudex

You need to subscribe to Steve’s channel, and go over this 4 part video.
Learn about ipsilateral and contralateral audio reflections , and other tools, stuff, before throwing around panels .

At one time I had strived to re-write this thread .. intro, tools, etc.
Even have draft posts in the test thread section. Young kids / life got in the way.
There’s a lot of ... “old advice” here ..






I’ve had lots of people over my home theater , quite a few have moved their R and L outside their AT screen to increase the angle closer to 30 degrees, and were blown away by simple as that. Free to try it, I suggest you do so. 

Your room at 16 feet wide seems possible to me.

Sent from my iPhone 11Pro using Tapatalk


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## Mocs123

mtbdudex said:


> You need to subscribe to Steve’s channel, and go over this 4 part video.
> Learn about ipsilateral and contralateral audio reflections , and other tools, stuff, before throwing around panels .
> 
> At one time I had strived to re-write this thread .. intro, tools, etc.
> Even have draft posts in the test thread section. Young kids / life got in the way.
> There’s a lot of ... “old advice” here ..
> 
> I’ve had lots of people over my home theater , quite a few have moved their R and L outside their AT screen to increase the angle closer to 30 degrees, and were blown away by simple as that. Free to try it, I suggest you do so.
> 
> Your room at 16 feet wide seems possible to me.
> 
> Sent from my iPhone 11Pro using Tapatalk


Thank you for your help. I’ll have to check out that video series on Sunday when I’m not at work (Youtube is blocked at work). 
I can certainly try my speakers further out to the edges of the room, but if I only have 2’ on each side of my screen to the wall so that would be getting them pretty close to the corners. If I were going to leave them there permanently, I would also need to take my velvet panels apart and use an acoustically transparent fabric in the side panels instead of the velvet, but that would be doable if it was a noticeable improvement.


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## mtbdudex

Definitely put them in the corners , aim them at your MLP... 
Like this room , pro designed .
Make them flush via baffle plate, mitigate SIBR.










Sent from my iPhone 11Pro using Tapatalk


----------



## mkiv808

Have a somewhat challenging room that I'm finishing up soon. Here is the layout:










Ignore the backwards seats.  

Some changes to that layout in the actual room:


My front Atmos speakers wound up being closer to walls and wider because of issues with ceiling joists. Also moved them forward a bit, and the first row of seating will be closer to riser. 
There's no foundation half wall, I just covered that completely with floor to ceiling framing and made a flat wall in drywall instead of doing a step.

It's a tricky layout because of the slider and the window. Both will have black velvet blackout curtains. Think I am going with these unless someone has a better suggestion: https://www.homedepot.com/p/Absolut...n-L-11718050X063BK/204812786?modalType=drawer

With those, I'll have 2 large areas on the left wall for absorption. I'm also lining the entire area behind the screen with 2 layers of 1" duct liner (Knauf Atmosphere). I will probably do bass traps in the front corners. I also have some vents in my platform riser in the corners and along wall (5 6x10" vents). Not sure it will be much of a bass trap, but will see. Floor is a pretty heavy, plush carpet and seating will be leather. 

Wondering where to take it from here as far as absorption panels, diffuser panels, or even hybrid absorption/diffuser panel placement. 

I would like to start small as this has not been a cheap exercise so far. 

Any suggestions would be welcomed.


----------



## mkiv808

Watched the video previously posted in the thread. Good info. 

Sounds like I will want to match the slider curtain and window curtain with absorbing panels on the opposite side of the room for symmetry?

And then next maybe 2 absorbing panels in rear. 

Later on, add a couple diffusers or combo panels in rear. 

Then add a couple diffuser panels or combo panels to sides of listening area.

Sound about right? 

I see he didn’t say much about bass traps. Are they worth doing in front corners with 2” of Linacoustic equivalent on entire front wall?


----------



## Ladeback

@mkiv808, how did you get the movie seats in magicplan? That's an interesting design program. I downloaded it on my phone and selected personal use, should I change it?


----------



## mkiv808

Ladeback said:


> @mkiv808, how did you get the movie seats in magicplan? That's an interesting design program. I downloaded it on my phone and selected personal use, should I change it?


Saved the photo and then added in Photoshop


----------



## shesaidsam

mtbdudex said:


> Definitely put them in the corners , aim them at your MLP...
> Like this room , pro designed .
> Make them flush via baffle plate, mitigate SIBR.
> 
> Sent from my iPhone 11Pro using Tapatalk





I'm running into a situation where my LR speaker are getting really close to my corners in a 13.3" wide room. If I move them closer to the edge of the 92" wide CIH screen inside or outside supports for the mask start to get in the way. I only have 24" of false wall to work with, and if I put the LR speakers equilateral from the listening position that puts them 20" from the side wall. Any reccomendations or up to date reading materials I should look into? I'm not too familiar with baffle walls or the corner placement you're showing.


----------



## moe80

*Absorption in rear theater wall*

Hi all,


Looking for some opinions/thoughts.
adding treatment to the back of my theater and my panels are just around 3.5" thick. I was going to put 2" of rockboard 40 with about 1.5" of air space.
Alternatively the supplier has ROckboard 60 which is 3"...leaving me with roughly .5" air space.


Thoughts on what is best? rock board 40 2" with 1.5" airspace or rockboard 60 3" with .5" air space.


Everything I read says the thicker the better...
Also, OC703 is not an option for me as I cannot get it locally, and I checked the coefficients on both products and they are close to identical really...


my room is 15.5 x 27'


rear seats are just over 3 feet from the back wall with the panels coming out 3.5"


thanks guys


----------



## mkiv808

I put my towers wide, almost to the corners. They’re also very close to the back wall. I have Linacoustic in corners and back wall. No bass traps. 

I find the soundstage good, but now my bass seems overpowering. Not as tight and clear as before. 

Is it wrong to have them very close to back wall? There’s no rearward firing driver. 

The only other thing I can think of is adding corner bass traps?


----------



## Mocs123

Has anyone used Rockwool Safe and Sound Batts for acoustic panels? I was going to use Rockwool Comfortboard 60 but I can't buy it locally and can only order it by the pallet. Shipping it doubles the price and makes it not very cost effective. Is there that much difference?


----------



## Ladeback

Mocs123 said:


> Has anyone used Rockwool Safe and Sound Batts for acoustic panels? I was going to use Rockwool Comfortboard 60 but I can't buy it locally and can only order it by the pallet. Shipping it doubles the price and makes it not very cost effective. Is there that much difference?


Didn't you see @genaccmiller's video on his build thread about using Rockwool Safe and sound for his acoustic panels that you commented on before this video? Looks like it can be used.


----------



## Mocs123

Ladeback said:


> Didn't you see @genaccmiller's video on his build thread about using Rockwool Safe and sound for his acoustic panels that you commented on before this video? Looks like it can be used.
> 
> https://youtu.be/CHz0ZrbbCaA



genaccmiller is the one who gave me the idea - and I know it can be used, but I was curious to how it compared to the Comfort Board 40/60/80 that Acoustimac and GIK Acoustic use. I was hoping someone had experience with both.


It looks like I can build 2'x4'x4" panels for $30.55 each and 2'x4'x8" bass trap panels for $49.80 each. Those same panels from GIK (which use Comfortboard 80) are $75 and $127.50 respectively plus shipping (which isn't cheap).


----------



## Ladeback

Mocs123 said:


> genaccmiller is the one who gave me the idea - and I know it can be used, but I was curious to how it compared to the Comfort Board 40/60/80 that Acoustimac and GIK Acoustic use. I was hoping someone had experience with both.
> 
> 
> It looks like I can build 2'x4'x4" panels for $30.55 each and 2'x4'x8" bass trap panels for $49.80 each. Those same panels from GIK (which use Comfortboard 80) are $75 and $127.50 respectively plus shipping (which isn't cheap).


Sound like a plan. I need to clean my basement and get my room done. What size is your room?


----------



## Mocs123

Ladeback said:


> Sound like a plan. I need to clean my basement and get my room done. What size is your room?



My room is 16x21x8 with a false wall and acoustically transparent screen making the room appear as 16x19x8. I'd love to have had another three feet of width, three or four feet of depth, and foot of height, but all four walls are load bearing so it is what is. I was (am) on a tight budget for my theater and there are some compromises but overall I think it turned out great.


----------



## Ladeback

Mocs123 said:


> My room is 16x21x8 with a false wall and acoustically transparent screen making the room appear as 16x19x8. I'd love to have had another three feet of width, three or four feet of depth, and foot of height, but all four walls are load bearing so it is what is. I was (am) on a tight budget for my theater and there are some compromises but overall I think it turned out great.


I am currently framed to 14'x25.75'x8.83'. Thinking of going to 16.83' wide.


----------



## Vikash sinha

JBS said:


> OK, this seems straightforward from searching AVS and studying theater wall treatment...
> 
> FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.
> CEILING: No acoustical treatment - none, nada.
> FLOOR: Thick, plush carpet is fine.
> 
> But here's where it gets confusing, and I need help...
> 
> SIDEWALLS
> A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.
> --or--
> B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.
> 
> These 2 theories seem to contradict each other. So which is it?
> 
> 
> BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:
> 
> Owens Corning Select Sound Black Acoustic Board
> Owens Corning Fiberglas 703 Series duct insulation.
> Johns Manville Insul-Shield
> Johns Manville Linacoustic Permacoate rolls.
> Certainteed Certpro Acoustaboard Black
> Knauf Duct board EI-475
> Knauf Duct liner EM
> 
> ...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.


Why no treatment for the celing?


----------



## Mocs123

Mocs123 said:


> genaccmiller is the one who gave me the idea - and I know it can be used, but I was curious to how it compared to the Comfort Board 40/60/80 that Acoustimac and GIK Acoustic use. I was hoping someone had experience with both.
> 
> 
> It looks like I can build 2'x4'x4" panels for $30.55 each and 2'x4'x8" bass trap panels for $49.80 each. Those same panels from GIK (which use Comfortboard 80) are $75 and $127.50 respectively plus shipping (which isn't cheap).





Well I ordered my Rockwool - It should be here the middle of June. None was in stock in my local store, so I ordered the 24x48 batts so I wouldn't have to cut them.


----------



## genaccmiller

Mocs123 said:


> Ladeback said:
> 
> 
> 
> Didn't you see @genaccmiller's video on his build thread about using Rockwool Safe and sound for his acoustic panels that you commented on before this video? Looks like it can be used.
> 
> https://youtu.be/CHz0ZrbbCaA
> 
> 
> 
> 
> genaccmiller is the one who gave me the idea - and I know it can be used, but I was curious to how it compared to the Comfort Board 40/60/80 that Acoustimac and GIK Acoustic use. I was hoping someone had experience with both.
> 
> 
> It looks like I can build 2'x4'x4" panels for $30.55 each and 2'x4'x8" bass trap panels for $49.80 each. Those same panels from GIK (which use Comfortboard 80) are $75 and $127.50 respectively plus shipping (which isn't cheap).
Click to expand...

You will definitely save money if you go the DIY route on this. Some people have a preference to only buy manufactured ones. It comes down to personal preference. Although I am surprised why your local home depot will not have the item I linked in my post above.

The additional advantage is you can also make movie posters on top of them. Check my video below on how I added movie posters on top of the panels.

https://youtu.be/-N9otVvLgbQ


----------



## mkiv808

mkiv808 said:


> I put my towers wide, almost to the corners. They’re also very close to the back wall. I have Linacoustic in corners and back wall. No bass traps.
> 
> I find the soundstage good, but now my bass seems overpowering. Not as tight and clear as before.
> 
> Is it wrong to have them very close to back wall? There’s no rearward firing driver.
> 
> The only other thing I can think of is adding corner bass traps?



Going back to this post. Wondering how close to have speakers to back wall. They’re very close and it sounds boomy. Linacoustic on wall.


----------



## genaccmiller

mkiv808 said:


> Going back to this post. Wondering how close to have speakers to back wall. They’re very close and it sounds boomy. Linacoustic on wall.


Mine is very close to wall and no boominess.

Sent from my GM1917 using Tapatalk


----------



## mkiv808

genaccmiller said:


> Mine is very close to wall and no boominess.
> 
> Sent from my GM1917 using Tapatalk



Hmm. I’m wondering if it could also be because I moved them closer to corners.


----------



## genaccmiller

mkiv808 said:


> Hmm. I’m wondering if it could also be because I moved them closer to corners.


Do you have treatments in your room?

Sent from my GM1917 using Tapatalk


----------



## moe80

Mocs123 said:


> Well I ordered my Rockwool - It should be here the middle of June. None was in stock in my local store, so I ordered the 24x48 batts so I wouldn't have to cut them.



I'm a bit late, only saw this now.


I just used rockboard 60 3" for my treatment in the rear wall and so far it has worked out well. The coefficients are real good.

And I'll be using Rockbaord40 2" to build my corner base traps shortly.


Very inexpensive and super effective


----------



## bcurtis53

Hi guys. I posted this in the DefTech thread but I feel that I should post it here as well. I'm building some absorption panels for my basement movie room (6: 27" x 45" x 3.5" panels) and I have a question. I know about locating and treating the first and second reflection points as is done with traditional speaker designs, but how do I adjust my thinking for bipolar towers? I have a pair of DefTech BP7001SC bipolar towers up front. I used the mirror trick to locate the 1st and 2nd reflection points on the side walls for the front-firing speakers. How do I locate them for the rear-firing drivers? Do I even need to? My thoughts so far are to get a second mirror and place it on the wall directly in front of the rear-firing speaker, and then moving a second mirror along the side walls to see where I can see the driver's reflection. I don't know why this is confusing me but it is. Ha! 



Has anyone attempted acoustic absorption (or diffusor) panels with their bipolar towers? I'd appreciate some guidance. Thanks! 



I have attached a sketch of the room to help with visualization.


----------



## bcurtis53

No one has dealt with room correction with bipolar speakers? I'll just experiment then. I'll start out by just treating the 1st and 2nd reflection points and back wall for the front firing drivers and the center channel. I'll see how the rear facing drivers sound with that and work from there. I'll share whatever I find.


----------



## Ladeback

bcurtis53 said:


> Hi guys. I posted this in the DefTech thread but I feel that I should post it here as well. I'm building some absorption panels for my basement movie room (6: 27" x 45" x 3.5" panels) and I have a question. I know about locating and treating the first and second reflection points as is done with traditional speaker designs, but how do I adjust my thinking for bipolar towers? I have a pair of DefTech BP7001SC bipolar towers up front. I used the mirror trick to locate the 1st and 2nd reflection points on the side walls for the front-firing speakers. How do I locate them for the rear-firing drivers? Do I even need to? My thoughts so far are to get a second mirror and place it on the wall directly in front of the rear-firing speaker, and then moving a second mirror along the side walls to see where I can see the driver's reflection. I don't know why this is confusing me but it is. Ha!
> 
> 
> 
> Has anyone attempted acoustic absorption (or diffusor) panels with their bipolar towers? I'd appreciate some guidance. Thanks!
> 
> 
> 
> I have attached a sketch of the room to help with visualization.


I have been watching YouTube. It may help to understand standing waves. They are long though.

The second one does talk about bipolar speakers.


----------



## bcurtis53

Ladeback said:


> I have been watching YouTube. It may help to understand standing waves. They are long though.
> 
> The second one does talk about bipolar speakers.
> 
> https://www.youtube.com/watch?v=_d3cLOO3urQ&t=1442s
> 
> https://www.youtube.com/watch?v=cUmb5fi7HLU&t=5174s


Thanks! I'll check it out.


----------



## cyan

Hi all,
I am wrapping up the final stages of my dedicated HT build and have come to an impasse with the question of acoustic treatments for my room, specifically the ceiling. Curious what the ideal approach would be given the following:
1) I want to avoid treating the back wall if possible
2) I prefer to avoid treating the side walls if possible
3) floor will be thick carpet, and front wall behind screen can be treated
4) Riser (14’x10’x15”) will be built as a bass absorber 
5) two rows of 3 leather recliners 

My room is 14’ wide and 22’ long, with a tray ceiling that is about 10’ wide and 17’ long. 

The entire ceiling will be a fiber star ceiling, with a 1” gap between. My initial plan was to use 2” foam board but I have given thought lately to using OC703 wrapped in AT velvet since the ceiling will be almost the only absorption I have for mid and high frequencies other than the carpet itself.

Is this a bad, good or medicore idea? Should I alternate panels with foam board and 703? I’ve seen a few comments to the effect of “treat the ceiling” but I think if I don’t the room will be way too reflective.

Thanks in advance for any suggestions from the experts!


----------



## NBPk402

cyan said:


> Hi all,
> I am wrapping up the final stages of my dedicated HT build and have come to an impasse with the question of acoustic treatments for my room, specifically the ceiling. Curious what the ideal approach would be given the following:
> 1) I want to avoid treating the back wall if possible
> 2) I prefer to avoid treating the side walls if possible
> 3) floor will be thick carpet, and front wall behind screen can be treated
> 4) Riser (14’x10’x15”) will be built as a bass absorber
> 5) two rows of 3 leather recliners
> 
> My room is 14’ wide and 22’ long, with a tray ceiling that is about 10’ wide and 17’ long.
> 
> The entire ceiling will be a fiber star ceiling, with a 1” gap between. My initial plan was to use 2” foam board but I have given though lately to using OC703 wrapped in AT velvet since the ceiling will be almost the only absorption I have more mid and high frequencies other than the carpet itself.
> 
> Is this a bad, good or medicore idea? Should I alternate panels with foam board and 703? I’ve seen a few comments to the effect of “treat the ceiling” but I think if I don’t the room will be way too reflective.
> 
> Thanks in advance for any suggestions from the experts!


I would build bass traps and do first reflection panels at a minimum. Front wall and floor should be ok.You can wrap the bass traps and first reflection panels in an acousically transparent cloth which can match your walls...then it is not noticable, or you can have artwork printed on the material.

Sent from my SM-T830 using Tapatalk


----------



## cyan

NBPk402 said:


> cyan said:
> 
> 
> 
> Hi all,
> I am wrapping up the final stages of my dedicated HT build and have come to an impasse with the question of acoustic treatments for my room, specifically the ceiling. Curious what the ideal approach would be given the following:
> 1) I want to avoid treating the back wall if possible
> 2) I prefer to avoid treating the side walls if possible
> 3) floor will be thick carpet, and front wall behind screen can be treated
> 4) Riser (14â€™️x10â€™️x15â€) will be built as a bass absorber
> 5) two rows of 3 leather recliners
> 
> My room is 14â€™️ wide and 22â€™️ long, with a tray ceiling that is about 10â€™️ wide and 17â€™️ long.
> 
> The entire ceiling will be a fiber star ceiling, with a 1â€ gap between. My initial plan was to use 2â€ foam board but I have given though lately to using OC703 wrapped in AT velvet since the ceiling will be almost the only absorption I have more mid and high frequencies other than the carpet itself.
> 
> Is this a bad, good or medicore idea? Should I alternate panels with foam board and 703? Iâ€™️ve seen a few comments to the effect of â€œtreat the ceilingâ€ but I think if I donâ€™️t the room will be way too reflective.
> 
> Thanks in advance for any suggestions from the experts!
> 
> 
> 
> I would build bass traps and do first reflection panels at a minimum. Front wall and floor should be ok.You can wrap the bass traps and first reflection panels in an acousically transparent cloth which can match your walls...then it is not noticable, or you can have artwork printed on the material.
> 
> Sent from my SM-T830 using Tapatalk
Click to expand...

Thanks. So then my question would be is using 703 across the entire ceiling going to make the room too dead, or would using foam board across the entire ceiling make it too live? Other than mixing foam and 703 those are my only two options.


----------



## NBPk402

cyan said:


> Thanks. So then my question would be is using 703 across the entire ceiling going to make the room too dead, or would using foam board across the entire ceiling make it too live? Other than mixing foam and 703 those are my only two options.


I would try the first reflection points on the ceiling before you try the whole ceiling. 

Sent from my SM-T830 using Tapatalk


----------



## cyan

NBPk402 said:


> cyan said:
> 
> 
> 
> Thanks. So then my question would be is using 703 across the entire ceiling going to make the room too dead, or would using foam board across the entire ceiling make it too live? Other than mixing foam and 703 those are my only two options.
> 
> 
> 
> I would try the first reflection points on the ceiling before you try the whole ceiling.
> 
> Sent from my SM-T830 using Tapatalk
Click to expand...

Unfortunately I don’t have that option. With a star ceiling the entire ceiling must be covered with something. Either all 703, all foam board, or a combo of both. That is what I’d like to know, which is best.


----------



## Snoochers

Let’s assume I’m starting with a basement foundation wall. How much wall thickness room is needed to create a finished and sound isolated Theatre room? Something that’s well sound isolated. I’m referring to the thickness of the 2x4s and drywall etc.


----------



## pkinneb

Snoochers said:


> Let’s assume I’m starting with a basement foundation wall. How much wall thickness room is needed to create a finished and sound isolated Theatre room? Something that’s well sound isolated. I’m referring to the thickness of the 2x4s and drywall etc.


In my case it was 6 3/4"
- 1" foam insulation glued to foundation
- 1" air gap
- 3 1/2" for 2x4 wall
- 1 1/4" - 5/8" double drywall

On top of that another 2 1/4" for the cloth covered OC703 wall panels if you go that route.


----------



## Snoochers

pkinneb said:


> Snoochers said:
> 
> 
> 
> Letâ€™️s assume Iâ€™️m starting with a basement foundation wall. How much wall thickness room is needed to create a finished and sound isolated Theatre room? Something thatâ€™️s well sound isolated. Iâ€™️m referring to the thickness of the 2x4s and drywall etc.
> 
> 
> 
> In my case it was 6 3/4"
> - 1" foam insulation glued to foundation
> - 1" air gap
> - 3 1/2" for 2x4 wall
> - 1 1/4" - 5/8" double drywall
> 
> On top of that another 2 1/4" for the cloth covered OC703 wall panels if you go that route.
Click to expand...

Thanks! So that’s 9” with the acoustic pannel, so 18” for walls on two sides.


----------



## pkinneb

Snoochers said:


> Thanks! So that’s 9” with the acoustic pannel, so 18” for walls on two sides.


In my case 17" as only two walls were block, the other two were interior walls and did not require the 1" foam.


----------



## Mocs123

I'm going to pickup my rockwool and 1x material on Friday after work and start building my acoustic absorption panels.


I'm planning on building seven 24"x48"x3.5" frames for acoustic panels in my room and one 48"x24"x9.5" bass trap for the back wall. 



I'd like to mount one of the panels on the ceiling as a cloud on the first reflection point - what is the best way to mount it to the ceiling? I know companies like GIK or Acoustimac sell mounting kits - is that the best way or is there something else to buy locally or from Amazon?


----------



## bcurtis53

Mocs123 said:


> I'd like to mount one of the panels on the ceiling as a cloud on the first reflection point - what is the best way to mount it to the ceiling? I know companies like GIK or Acoustimac sell mounting kits - is that the best way or is there something else to buy locally or from Amazon?



I would like to know this as well.


----------



## lax01

For the love of god, why doesn't ATS include a horizontal mounting template with their panels...I just found out they have a "special template" if you request it...which probably isn't possible if you buy on Amazon

I just beat my head against a wall for a couple of hours trying to install the stupid panel horizontally - I think I got it but I don't really know


----------



## Mashie Saldana

Mocs123 said:


> I'm going to pickup my rockwool and 1x material on Friday after work and start building my acoustic absorption panels.
> 
> 
> I'm planning on building seven 24"x48"x3.5" frames for acoustic panels in my room and one 48"x24"x9.5" bass trap for the back wall.
> 
> 
> 
> I'd like to mount one of the panels on the ceiling as a cloud on the first reflection point - what is the best way to mount it to the ceiling? I know companies like GIK or Acoustimac sell mounting kits - is that the best way or is there something else to buy locally or from Amazon?


I used these for my GIK ceiling panels, they are extremely easy to install and adjust:


----------



## PoorSignal

Hi guys I am waiting for some GOM fabric, I am using 1x3 wood for my panels
My question is when you wrap it did you recommend glue or is staple only good enough?

And also I notice speaker grills are usually glued as well?

If glue what kind of glue? I usually used 3M 77 for other stuff. 

Thanks


----------



## pkinneb

I only used staples on mine, glue was not necessary.


----------



## Mashie Saldana

PoorSignal said:


> Hi guys I am waiting for some GOM fabric, I am using 1x3 wood for my panels
> My question is when you wrap it did you recommend glue or is staple only good enough?
> 
> And also I notice speaker grills are usually glued as well?
> 
> If glue what kind of glue? I usually used 3M 77 for other stuff.
> 
> Thanks


I used spray glue and staples. Still going strong 3 years later.


----------



## AndreNewman

Just staples, plenty strong enough.


----------



## PoorSignal

How high do you usually mount 4' high panels? 8' ceiling, thanks


----------



## Pretorian

I am getting more and more interested in acoustical treatment for my home cinema. It is a jungle out there. Is there a "simple" beginners guide that I can start with?
How did you start and how was the result? Was it worth the effort and the money?


----------



## sdurani

PoorSignal said:


> How high do you usually mount 4' high panels?


Centre them at your seated ear height.


----------



## AndreNewman

Looking for some advice.

I built 300mm square floor to ceiling bass traps for the front of the room, largest I could fit alongside our screen.

Sometime soon I want to build some for the rear corners and unsure if I should build them as big as fits, 400x455 could fit. Or if I should build them the same as the front ones so they “balance” if that’s a thing?

The reason I ask is I recently got a second subwoofer and positioned the two at the classic 1/4 and 3/4 length positions. I’ve been reading Floyd Toole. I found to get them to balance out the room length mode at 31Hz I had to move one away from the 1/4 position closer to 1/3. I wonder if the bass traps at the front are causing this?

I understand that 300mm traps are not going to do anything much at 31Hz, probably 400mm won’t do much either.

Thanks


----------



## HopefulFred

Balancing bass traps is not a thing. If you have need for more bass trapping (virtually everyone does), devote as much space to it as you are comfortable. That said, I would prioritize subwoofer location over bass trap location - which is to say, if the ideal location for the sub is where you would otherwise place a trap, put the sub there and trap elsewhere.


----------



## Soulburner

AndreNewman said:


> Looking for some advice.
> 
> I built 300mm square floor to ceiling bass traps for the front of the room, largest I could fit alongside our screen.
> 
> Sometime soon I want to build some for the rear corners and unsure if I should build them as big as fits, 400x455 could fit. Or if I should build them the same as the front ones so they “balance” if that’s a thing?
> 
> The reason I ask is I recently got a second subwoofer and positioned the two at the classic 1/4 and 3/4 length positions. I’ve been reading Floyd Toole. I found to get them to balance out the room length mode at 31Hz I had to move one away from the 1/4 position closer to 1/3. I wonder if the bass traps at the front are causing this?
> 
> I understand that 300mm traps are not going to do anything much at 31Hz, probably 400mm won’t do much either.
> 
> Thanks


I've had corner traps change my bass enough that it caused me to move my speakers - but we're talking about changes in the 150-300 Hz range. There was zero effect below 80 Hz. The measurements perfectly overlaid each other with and without bass traps below 80 Hz and only differed by about 1% at 100 Hz.


----------



## AndreNewman

HopefulFred said:


> Balancing bass traps is not a thing. If you have need for more bass trapping (virtually everyone does), devote as much space to it as you are comfortable. That said, I would prioritize subwoofer location over bass trap location - which is to say, if the ideal location for the sub is where you would otherwise place a trap, put the sub there and trap elsewhere.


Thanks, that was what I thought, I just had a moment wondering if I’d misunderstood.


----------



## AndreNewman

Soulburner said:


> I've had corner traps change my bass enough that it caused me to move my speakers - but we're talking about changes in the 150-300 Hz range. There was zero effect below 80 Hz. The measurements perfectly overlaid each other with and without bass traps below 80 Hz and only differed by about 1% at 100 Hz.


That’s interesting, my room response for left and right is horrible between 120 and 200Hz. The traps I’ve built help significantly so hoping a few more will fix it.

The biggest problem was that Left and Right are too close to the corners, forced there by the largest screen we could fit, 300mm bass traps in those corners have helped but more is needed. I haven’t done anything on the back wall or rear corners yet.

I bought a second sub to reduce a 31Hz. peak and fill a 23Hz null. It seems to have mostly worked and also filled out some nulls up to 120hz, when eq’d by a minidsp. I don’t really want to crossover silver 8 floorstanders at 120Hz so I’ll build the biggest traps I can reasonably fit at the back and hope it helps 120 to 200Hz further.

It sounded a great deal better when I built the front corner traps. Better again when I got the second sub equalised. Better when the crossovers were improved yesterday. Messy response between 120 and 200 is main thing to improve, 400mm square full height corner traps ought to do something meaningful down at 120Hz?

I can hopefully put several 100mm panels on the back wall too.


----------



## catinthehat85

Has anyone here experimented with acoustic wood panels? Essentially it’s wood planks with gaps between the wood with acoustic foam underneath. I’m planning on doing this for my ceiling and still figuring the amount of gap I want/need and the type/thickness of foam underneath.


----------



## AndreNewman

Does anyone have an idea how a corner square bass trap compares to an equivalent sized edge absorber?
For example I'm considering a 400mm x 400mm x 2.4m bass trap compared to a 600mm x 100mm x 2.4m panel fitted across the same corner. On my plans they take up approximately the same space but of course the diagonal panel uses a lot less material and is easier to handle.

I'm mostly trying to reduce a ~200Hz null where length and width axial modes collide but any cleanup between 150Hz and 300Hz is welcome.


----------



## 230-SEAN

Prior to the site's design change, there used to be a "search this thread" at the top of thread. This either no longer exists or I'm not savvy enough to find it. Forgive me as I'm sure this has been asked but I can't find it. That being said:

Have treatment basics changed with Atmos? Is it still treat the front wall floor to ceiling and all other walls with 1" absorption from floor to just above ear height? If it has changed, I'd imagine some change due to height speakers, could someone point me to the most up to date info? 

Thanks!

-Sean


----------



## John M Miller

I'm wondering if I could get some opinions on how to frame out the boxes for my speakers. My dedicated theater will have an acoustically transparent screen with KEF LS50s serving LCR duties. I'm debating four questions:
1) Do I frame out each LCR speaker individually or just make one big box back there? If I frame out each individually I don't have to move the garage door opener, light switches and power switches. But sound quality is most important.
2) What material do I use? Two options would be bare 3/4" MDF (which I'm also using for the top of the subwoofer box) or 2x4s and drywall.
3) What do I put inside the box? No, not my junk-- I'm talking sound treatments. Pink fluffy stuff? 703? Roxul? Something else? What about directly underneath the speakers?
4) Reading other threads it appears as though the best thing for the subs underneath is to frame it out with 2x4s and drywall. But I'm open on that. I plan on making a large speaker grill out of AT fabric and 1x2s to hide the subs.

Any help appreciated!
Thanks!


----------



## harrisu

Hey guys,
A quick question regarding Linacoustic. Do either side absorb high frequencies equally or 1 side is more effective than the other?


----------



## pkinneb

My understanding is you want the hard side out but not sure it effects absorption I think its becuase it keeps the fibers from releasing into the room.


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## wookiegr

I asked this is another topic but may not have been the right place. I was wondering is anyone sealed and hardened the edges of the 2" owen's corning 703 with acrylic and simply wrapped the panel as-is without building wooded frames. I've seen several uses of this online where you just pop the wrapped panel onto impaling spikes on the wall and you're done. I know you need a gap and would use a spacer but still. Has this method been used and what's the opinion on it.


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## b_scott

do people find that treating the ceiling with acoustic panels for very small rooms (13x13) does much? Rug on the floor, 703 panels on the walls and 703 4" bass traps in the corners. I am covering the ceiling with velvet.


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## Kal Rubinson

I suspect that velvet will do little or nothing for/to audio. If it is dark in color, it may help with video.


----------



## b_scott

Kal Rubinson said:


> I suspect that velvet will do little or nothing for/to audio. If it is dark in color, it may help with video.


yeah I'm not doing velvet for audio. It's to block light reflection.


----------



## b_scott

does anyone have easy to follow instructions for building a quadratic resonance diffuser? i want a horizontal one for my wall behind my chairs. Maybe 4 feet wide by 2 feet tall with vertical slats.


----------



## MinHeadroom

b_scott said:


> does anyone have easy to follow instructions for building a quadratic resonance diffuser? i want a horizontal one for my wall behind my chairs. Maybe 4 feet wide by 2 feet tall with vertical slats.


Hope this helps: QRDude: Quadratic Residue Diffuser calculator


----------



## matt-sf

Hi Folks.

I'm building out my basement home theater. The build thread is here. We are using 2x6 studs for the framing, and have acoustic panels on the walls (floor to ceiling) that are designed to be hung in front of an absorptive material (Soundply AP).

Note that not all the panels are absorptive, my audio engineer recommended some to be reflective. I think this is to avoid the room being too dead.

The audio engineer recommended using Autex Quitespace in back of the panels. However it is an expensive product. From the data I've seen, 4" Mineral Wool, such as Rockboard 40 has incredible absorption properties, with NRC's ranging from 1.03 at 125 hz to 1.08 at 4000 hz.

Is there any reason not to go with a rockwool solution? Can you have too much absorption?


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## Dirt9

I dont know. my room is 13x22x8', I went full absorption and made 18 panels 24x48x6" and stacked all four corners floor to ceiling with eight 24x36x48" column absorbers.worked great.ended up with a pretty even decay time.rock wool and pink fluffy.DIY $300 for everything.
Some say rockwool is unhealthy.


----------



## MinHeadroom

b_scott said:


> do people find that treating the ceiling with acoustic panels for very small rooms (13x13) does much? Rug on the floor, 703 panels on the walls and 703 4" bass traps in the corners. I am covering the ceiling with velvet.


Did you ever decide on a ceiling panel and how to use it with velvet? I have GOM for transparency reasons and I won’t add black velvet to the mix- out of fear that my black GOM will turn gray!


----------



## b_scott

MinHeadroom said:


> Did you ever decide on a ceiling panel and how to use it with velvet? I have GOM for transparency reasons and I won’t add black velvet to the mix- out of fear that my black GOM will turn gray!


hey there - I didn't do any ceiling panels, and I think it's OK. Sorry what is GOM?


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## LexaPr0

Dirt9 said:


> I dont know. my room is 13x22x8', I went full absorption and made 18 panels 24x48x6" and stacked all four corners floor to ceiling with eight 24x36x48" column absorbers.worked great.ended up with a pretty even decay time.rock wool and pink fluffy.DIY $300 for everything.
> Some say rockwool is unhealthy.


I don’t want to ‘thread steal’ but do you have a build thread? I’d like to see the results. 


Sent from my iPhone using Tapatalk


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## MinHeadroom

b_scott said:


> hey there - I didn't do any ceiling panels, and I think it's OK. Sorry what is GOM?


Oh sorry, “Gibraltars of Maine” fabric- they have two kinds of fabric that are frequently used for acoustically transparent fabric over speakers, absorbers, diffusors, etc. 

It’s pretty black, but anything black near black velvet tends to look gray.


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## AndreNewman

LexaPr0 said:


> I don’t want to ‘thread steal’ but do you have a build thread? I’d like to see the results.


 Yeah, me too.

I converted the dimensions to metric and went "wow", that's some serious bass traps, my fridge is smaller.


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## sdurani

MinHeadroom said:


> “Gibraltars of Maine” fabric-


Guilford of Maine: High-Performance Textiles - Guilford of Maine


----------



## MinHeadroom

sdurani said:


> Guilford of Maine: High-Performance Textiles - Guilford of Maine


I’m the worst- must have been having a stroke while i typed that


----------



## Jan3

matt-sf said:


> Is there any reason not to go with a rockwool solution? Can you have too much absorption?


Yes you can have too much absorption. You can partly cover your rockwool absorption panels with BAD panels for example, so only part will be absorbed and the rest will be diffused. When I made my DIY rockwool panels, I put a 4mm MDF sheet in front and cut random holes. This way, high frequencies won't be all absorbed and the low (difficult) ones might.


----------



## Dirt9

LexaPr0 said:


> I don’t want to ‘thread steal’ but do you have a build thread? I’d like to see the results.
> 
> 
> Sent from my iPhone using Tapatalk





AndreNewman said:


> Yeah, me too.
> 
> I converted the dimensions to metric and went "wow", that's some serious bass traps, my fridge is smaller.


I dont have a build thread and my room isn't exactly pretty,still in the build phase and the treatments are not mounted yet just leaned up but preforms great.I can take some pictures for you guys and upload some measurements.


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## knowlesm

Cross posting this with a new build thread...

I have read the most recent 100+ pages of this thread (covering last 5 years) and may have more questions than answers at this point.

When covering the front wall (behind an AT screen), seems like there are a couple main approaches:

Two layers of 1" linacoustic, with some plastic sandwiched between
2-4" of either OC703 or Rockwool
I am leaning towards using 4" of OC703 / Rockwool given they have better broadband absorption (https://www.bobgolds.com/AbsorptionCoefficients.htm), but have not read anything that tells me this is definitively better. I know a lot of people use the linacoustic, but this thread / approach is now 17 years young and materials certainly could have changed since the initial recommendation. Thoughts?

Room is 13' wide, 7.5' tall, and 40' deep. Main seating position is 16' from the front wall...behind the seating, the room does open up a bit to the rest of the basement (tho doors can be closed)


----------



## Dirt9

treating behind the screen would be the last thing done and only if the measurements show it needs it
Making you ryour panels out of rock wool would be the least expensive and best performance at 6" thick or more.since they would be hidden it would be a good time to try your hand at DIY.


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## knowlesm

Dirt9 said:


> treating behind the screen would be the last thing done and only if the measurements show it needs it
> Making you ryour panels out of rock wool would be the least expensive and best performance at 6" thick or more.since they would be hidden it would be a good time to try your hand at DIY.


Thank you. I understand the thought behind measuring before treating...that's probably the best approach. However, if there are things that are always / very often done, I'd like to knock them out before the screen is built, furniture is placed, etc. Treatment behind the screen seems to be ubiquitous in the build threads, hence my desire to get it in place before everything else comes together.


----------



## MinHeadroom

knowlesm said:


> Thank you. I understand the thought behind measuring before treating...that's probably the best approach. However, if there are things that are always / very often done, I'd like to knock them out before the screen is built, furniture is placed, etc. Treatment behind the screen seems to be ubiquitous in the build threads, hence my desire to get it in place before everything else comes together.


I get this. It ain’t easy to add space behind a screen and support columns AFTRT they are up. This allows for tweaking as you build, which is kind of how I have been going about it.


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## iron4044

Acoustic Panels Back Only?

Assuming I wanted to have some type of wall decorations (posters, art, etc... ) acoustic panels seem to limit these choices because the material covering the panel needs to be a mesh or 'breathable', right?

I'm just wondering, as a work around, would there still be a noticeable improvement in sound if:

The front of the panel was covered by a poster/paper
But with the back of the panel 'open' or covered with mesh material
And the panel itself was set off 1" - 2" from the wall, with spacers
So the back side of the panel would be catching/absorbing the reflections, etc.?
TIA!


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## Dirt9

^^^^^ Spacing the absorbers out from the wall up to 6"will make them more effective in the lower frequency 1000 hz and down.

Covering the front side with posters ,1"x2" wood strips spaced every 3/4" or even plastic or craft paper under the fabric will reflect high frequencies while still absorbing low frequencies and can be desirable if the room gets to dead. 

panels designed to reflect high frequencies are marketed with range limiting technology if you where to go buy pre made panels.


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## iron4044

Dirt9 said:


> ^^^^^ Spacing the absorbers out from the wall up to 6"will make them more effective in the lower frequency 1000 hz and down.
> 
> Covering the front side with posters ,1"x2" wood strips spaced every 3/4" or even plastic or craft paper under the fabic will reflect high frequencies while still absorbing
> low frequencies and can be desirable if the room gets to dead and is marketed as range limiting technology if you where to go guy pre made panels.


Thanks but I didn't understand the 2nd part..


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## Dirt9

Dirt9 said:


> ^^^^^ Spacing the absorbers out from the wall up to 6"will make them more effective in the lower frequency 1000 hz and down.
> 
> Covering the front side with posters ,1"x2" wood strips spaced every 3/4" or even plastic or craft paper under the fabric will reflect high frequencies while still absorbing low frequencies and can be desirable if the room gets to dead.
> 
> panels designed to reflect high frequencies are marketed with range limiters if you where to go buy pre made.


----------



## wookiegr

Changing the subject to me for a second. I just bought 6 of the ATS Acoustics 2" thick 24"x48" panels with Guilford Pitch. I've been slaving away building my home theater for nearly 18 months now and decided to treat myself to something bought and not DIY to speed things up. I really want to get my movies going and spend less time building everything. I assume these will be good panels and if not, oh well.


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## Dirt9

Yeah there all pretty much the same inside.
Those will work great to make everything more focust in the front sound stage.
Thicker panels just absorb more bass frequencies.


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## Dirt9

^^^^^^ taking measurements and adjusting the absorbers, taking measurements and adjusting was the hardest part for me.
Lots of moving stuff around.my walls got scuffed up pretty good.
Im definitely getting the room dialed and painting last if there's a next time lol


----------



## steve0742003

I am beginning to take the plunge into room acoustics. I have added rockwool above my drop ceiling and I am going to make some DIY movie poster acoustic panels for the 1st and second reflection points next. I have used the mirror method to find the reflection points. As you can see from the pics the second reflection points are marked but my issue is the 1st reflection points. I have shelving for my movie collection on either side of the room and the reflection points fall roughly in the middle of each shelf. Should I make 2 basic cloth covered panels and put below the shelving? Should I just not bother with that area? I could move the shelves if I felt motivated enough but I do like where they are located. Any suggestion are appreciated! (Just ignore the clutter and dust in my pics


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## Dirt9

^^..maybe try puting panels up where the tape is just past the shelving then measure with rew and see whats happening.


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## sdurani

steve0742003 said:


> Should I just not bother with that area?


I wouldn't bother with ipsi-lateral (same side) first reflections. If anything, they'll widen the soundstage slightly, which can sound nice. However, I would absorb the contra-lateral (opposite side) first reflections. Maybe that's what you meant 2nd reflection points? In any case, look for where the left speaker reflects off the right side wall and vice versa. Those are good locations for broadband absorption. This way, sounds intended for one end of the soundstage aren't also heard (however subtly) from the opposite side of the room.


----------



## steve0742003

sdurani said:


> I wouldn't bother with ipsi-lateral (same side) first reflections. If anything, they'll widen the soundstage slightly, which can sound nice. However, I would absorb the contra-lateral (opposite side) first reflections. Maybe that's what you meant 2nd reflection points? In any case, look for where the left speaker reflects off the right side wall and vice versa. Those are good locations for broadband absorption. This way, sounds intended for one end of the soundstage aren't also heard (however subtly) from the opposite side of the room.



Yes. The opposite side first reflections is what I was referring to as the second reflection point. I am finally at a point where I am happy with the equipment that I have in my setup (For now . Acoustic treatments is a whole new world for me and I have a lot to learn yet!

I am going to order a pack of rockwool to use for panels so I will have enough to make 6 panels. I know I will definately be using two. I have read that the back wall is also a good location to place some panels so will probably place 2 back there. Would placing the remaining 2 under the shelving at the same side reflections have much of an effect? I am not sure how the shelving itself might affect reflections.

Thank you for the replies.


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## sdurani

With 6 panels I would do a couple at the side wall contra-laterals, a couple at the middle of the back wall, and the last two butted up against screen (to absorb boundary reflections from the L/R speakers that could result in a cancellation notch).


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## bommai

My 8th grade son is interested in doing a science project for school on acoustic treatment. I asked him to limit his research to taming the first reflection point. We already have REW, UMIK-1, a PC with HDMI, a Denon X4300H receiver, a variety of speakers even though I asked him to use the JBL Studio 530 (since it would be easier to move if needed). I also have the mineral wool board (2" x 2' x 4') as well as I can procure the fiberglass boards (if needed). I also have the fluffy insulation batting (roll). I would greatly appreciate it if some of you can share some links to scientific journals for background information that he can read up on. When I google this topic, it is mostly blogs and people selling stuff that comes up. I did give him an informative article from GIK acoustics, but if there are more articles, that will be great.

I suggested to him that he should get a baseline reading in REW using no acoustic treatment. May be he should do specific frequencies using REW. I am a novice when it comes to acoustic treatment. I know the concept of first reflection. I have not done the treatment so I am hoping his experiment may even shed some light in our room. BTW, our media room is 15'W x 21'L x 8'.

I was also hoping to limit his experiment to just one speaker since it is mostly repetition after that (with all the other speakers).

Thanks in advance.


----------



## tnaik4

Hello guys.

When doing measurements with rew, should i set my MLP in the place i get the best measurment ? My room is 4.6m x 3.2m x 2.9m and treated with acoustic panels.

The best place i get is 3.5m away from the screen, which 1.1m from the back wall.

I m trying to determine the best place before i start my full dirac live calibration. I do have bass traps on the back with 2 4"panels , i couldnt do anything on the front wall due to constraint. The side and ceiling is covered for reflection points. Also there is a thick rugg on the whole floor.

Anything i can do with placement to improve things? I cant add much more panels, i do have a double slope ceiling so not sure how much is that affecting things.

Sorry about the mess, i just finished building this theatre and still need to put the final touches on it and clean it.


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## 187crew003

would there be any benefit from doing a chunky corner bass trap in only one corner? using roxul as the insulation floor to ceiling?


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## harrisu

sdurani said:


> With 6 panels I would do a couple at the side wall contra-laterals, a couple at the middle of the back wall, and the last two butted up against screen (to absorb boundary reflections from the L/R speakers that could result in a cancellation notch).


What do you think about GikAcoustic combo panel? Here is the link GIK Acoustic 
Here is what I currently have









First panel is covered with Black velvet to absorb light. I punched a lot of holes on it and put reflective paper to reflect high frequencies as much as possible. The pattern you see is with 12x12 4" thick absorbers and 12"x12" diffuser. Not shown here but I'm absorbing on ceiling above MLP and also at 1st reflection point with checker patter but not diffusing. So you can see that I'm not over absorbing. 
What's getting me more interesting in GIK combo panel is that they will reflect all high frequencies and absorb low ones. So Dialogs will be as clear as they can get but I'll end up getting more dispersion. So all in all, more absorption in dialog areas and more desperation with higher frequencies. I use JBL 4722N as L/C/R

What do you think??? That will cost me 600.00 but wondering if its worth it???????


----------



## sdurani

harrisu said:


> What do you think??? That will cost me 600.00 but wondering if its worth it???????


No way for me to put a value on it since I can't hear the results using your ears in your room. Do they have a good return plan? If so, try them out and see if they improve the sound of your system.


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## harrisu

sdurani said:


> No way for me to put a value on it since I can't hear the results using your ears in your room. Do they have a good return plan? If so, try them out and see if they improve the sound of your system.


Yeah I think they have 30 days return policy. I was asking my theoretically that if 1st reflection for Center and 2nd for L/R are absorbed for vocals and diffused for higher frequencies, does it sound good??? I guess you haven't heard such setup?


----------



## sdurani

harrisu said:


> I was asking my theoretically that if 1st reflection for Center and 2nd for L/R are absorbed for vocals and diffused for higher frequencies, does it sound good???


Sound good to who? It's very subjective. I tried absorption & diffusion at the Centre speaker's first reflection points and kept coming back to bare wall. I don't expect others to have the same preference as me. When you say "2nd for L/R", do you mean their second reflection points or the contra-lateral first reflections? If the latter, I prefer to absorb those. YMMV.


----------



## ereed

Like Sanjay says....you have to go by what you prefer. Try it bare wall and then try it with diffusion and absorption and which sounds better to you. There is really no right or wrong way. The only wrong way IMO is not a treated room at all. Having some treatment here and there is a must....only you have to figure out where and what type.

For me personally I use absorption on the first and second reflection points on the side walls and diffusion/absorption combo in between those. For the ceiling I prefer absorption and for the rear wall I'm using both diffusion/absorption combo. My front wall behind my theater screen is mostly bass absorption since that is where biggest pressure point of bass is located as well as the corners.


----------



## harrisu

sdurani said:


> When you say "2nd for L/R", do you mean their second reflection points or the contra-lateral first reflections? If the latter, I prefer to absorb those. YMMV.


I was referring to contra-lateral first reflection (1st reflection on opposite side). I am treating it as well but with the mix. I think it all depends on how much of distance there is b/w that point and MLP. In my case its not a lot of space and if I only absorb it, it feels more dead in room. With diffusion/absorbtion gives a good balance.
I'm intrigued by your idea of Center being not treated. You don't want to diffuse it? I understand that absorbing it might take the spaciousness but using a combo panel will make the dialog cleaner and diffuse higher frequencies unless you don't like to diffuse Center 1st reflection and like them getting reflected more?


----------



## sdurani

harrisu said:


> I'm intrigued by your idea of Center being not treated. You don't want to diffuse it?


Tried it with skylines, which resulted in a sort of diffuse halo effect in the background. Came back to bare walls, which caused dialogue to float slightly forward of my Centre speaker. Maybe it's my hearing but I've noticed that some early reflections seem to detach sounds from speakers. I can still point to where those sounds are but they don't appear to be coming from a physical speaker.


harrisu said:


> I understand that absorbing it might take the spaciousness but using a combo panel *will make the dialog cleaner* and diffuse higher frequencies unless you don't like to diffuse Center 1st reflection and like them getting reflected more?


From Toole's _'Loudspeakers & Rooms'_ paper:


> Readers who have been keeping score will have noted a distinct absence of negative effects from reflections on any aspect of speech perception we have looked at. In fact, the effects range from neutral to positive. No single reflection has been shown to be a problem for speech reproduction in small rooms (see Table 1). Multiple early reflections contribute even more to intelligibility.


 http://www.wghwoodworking.com/audio/loudspeakers_and_rooms_for_sound_reproduction.pdf


----------



## lavakv

Planning on treating the entirety of a recently created 30" deep false wall which houses the LCR and one of the sub's behind a 140" 2.35 AT screen. I believe the rather significant depth affords me an opportunity to attempt some decent velocity targeted bass absorption. I happen to have some R38 (12" thick pink fluffy) on hand from another recent home project which, per modeling (Multi-layer Absorber Calculator) should do rather well, either with or without a gap.

2ft depth outperforms other setups <70Hz but would require twice the insulation (minor cost) and would leave no gap for getting back in there for future work (nuisance).
1ft thick on the exterior wall (0ft gap) would be simplest to install, but seems the worst in modeling.
1ft thick with 1ft air gap would allow me to support via the false wall and models well.
Thoughts? Better options back there given the depth? Bass trapping with pink fluffy seems a contentious topic in some parts, but I see it used (admittedly not alone) in some well designed setups like _The Beast Unleashed_.


----------



## denslayer

I'm going to be making DIY acoustic panels . What's the consensus on type of insulation or absorbing material to use?


----------



## lavakv

Well I answered my own question from a post back. I friction fit the 12" thick batts tightly around LCR (and sub) behind the false wall with about a 12" air gap to the wall and was quite impressed with the improvement. Particularly happy with the reduction in ringing <100Hz with significant improvement ~22Hz. I don't quite believe what I'm seeing at 22Hz but that does match a room mode (26ft depth) which the false wall would be appropriately positioned to intercept.

Waterfalls/spectrograms were a bit better with the gap than with the insulation directly on the wall. Almost as pleasing as the bass cleanup was the improvement to soundstage width/clarity/imaging (albeit compared to a nearly untreated front wall). If I didn't already have the insulation, this would have cost ~$75 with some batts left over for other traps; seems a no brainer for anyone hunting bang for buck.


----------



## Harkon

I'm not sure whether this is more appropriate here or the Sound Proofing thread. 

Most people suggest filling the soffit with fluffy insulation. I'm guessing it reduces vibrations and resonance at the very least, at best it might act as a large bass trap. 

I'm hoping to make my soffit with removable panels to allow future cabling, access to fans/duct, pelmet sockets etc if it is ever needed.

With that in mind I'm not massively keen on using loose insulation. I'm sure I saw someone on AVS use pillows instead! Similar material and can be pulled out and put back in if needed, without covering everything with fiberglass/mineral wool insulation. 

Has anyone done this or seen it done? Any reason to not do it?


----------



## Supraquick

I am new to the forum, but was hoping someone here might have seen a practical application of the Volf Sound Diffusor in a metropolitan movie theater as referenced in this short article.


----------



## howiee

Hey guys. I'm thinking of wrapping 20mm insulation board in velvet for panelling our room. Eventually walls and ceiling. I'm not at all clued up on accoustic treatment and was wondering if this will have an adverse effect?


----------



## Mashie Saldana

howiee said:


> Hey guys. I'm thinking of wrapping 20mm insulation board in velvet for panelling our room. Eventually walls and ceiling. I'm not at all clued up on accoustic treatment and was wondering if this will have an adverse effect?


Yes, it will only kill the very highest frequencies and do nothing at all with those that you want to get rid off. 

You want a nice mixture of diffusion and absorption, in this case absorption 50mm+, preferably 100mm+ if you have the space.


----------



## howiee

Mashie Saldana said:


> Yes, it will only kill the very highest frequencies and do nothing at all with those that you want to get rid off.
> 
> You want a nice mixture of diffusion and absorption, in this case absorption 50mm+, preferably 100mm+ if you have the space.


Cheers for that, Mashie. I'll have a look at an alternative, or a tweak to the exisiting plan. Adding various thicker panels in the right places would be an option - up to the widths you mentioned. The reason for 20mm panels is due to surface mounted spotlights on the ceiling that stick out that far and wanting to bring the panels flush. Other than the panels around the spotlights, any width is fine.


----------



## Eskimo1

lavakv said:


> Well I answered my own question from a post back. I friction fit the 12" thick batts tightly around LCR (and sub) behind the false wall with about a 12" air gap to the wall and was quite impressed with the improvement. Particularly happy with the reduction in ringing <100Hz with significant improvement ~22Hz. I don't quite believe what I'm seeing at 22Hz but that does match a room mode (26ft depth) which the false wall would be appropriately positioned to intercept.
> 
> Waterfalls/spectrograms were a bit better with the gap than with the insulation directly on the wall. Almost as pleasing as the bass cleanup was the improvement to soundstage width/clarity/imaging (albeit compared to a nearly untreated front wall). If I didn't already have the insulation, this would have cost ~$75 with some batts left over for other traps; seems a no brainer for anyone hunting bang for buck.


Do you have any photos of how you held all of that in place? I'd like to try the same thing, but am having a hard time with visualizing how to keep it put.


----------



## lavakv

Eskimo1 said:


> Do you have any photos of how you held all of that in place? I'd like to try the same thing, but am having a hard time with visualizing how to keep it put.


Didn't document that bit as I would have if there was something clever in play. I just cut the batts such that they fit (tightly) around the LCR and the Marty housed in the false wall. Thinner "pink" fluffy would probably fold/crumple under its own weight the way I have it freestanding, but the whole 48" tall, 12" thick can just about stand up on its own once expanded. That plus the support from the speakers, and the friction between neighboring batts keeps them nice and tight.

Scanning your Quinema build thread and you seem to be planning a setup near identical to mine. I'll have to get a few pictures of my current state to put in there so as not to clutter this thread, but below is a very crude sketch of how the batts fit (from memory).


----------



## ScottieBoysName

I’m debating on how I want to start blacking out the rather light colored carpet at the front of my room. In the attached pictures, you can see I’ve got the side walls, ceiling, and front wall done. 

I have a treated room currently. 

I was considering wrapping several 2 foot x 4 foot pieces of plywood with velvet, and fitting them together on the floor like a puzzle. Just basically laying them on the carpet. Prolly come out 3-4 feet with it from the front going back (match the sidewalls).
















It occurs to me that this might alter the sound a bit as I the board wrapped velvet might have different reflective properties than the carpet. 

Is that correct? If so - will it be noticeable?


----------



## pkinneb

I can't answer your sound question but I would use 1/2" MDF not plywood. Its a lot more stable and will stay flat plywood will have a tendency to warp and cheap plywood will be even worse. If you do go with plywood seal both sides with polyurethane before adding the velvet if you use MDF you can skip it.

Btw great theater!! I really like those panels!


----------



## ScottieBoysName

pkinneb said:


> I can't answer your sound question but I would use 1/2" MDF not plywood. Its a lot more stable and will stay flat plywood will have a tendency to warp and cheap plywood will be even worse. If you do go with plywood seal both sides with polyurethane before adding the velvet if you use MDF you can skip it.
> 
> Btw great theater!! I really like those panels!


Thanks! Good point. They won't be "attached" to the floor like the panels on the walls. Plywood would be a bad idea, you're right. The panels on the walls were made from 1/4 inch plywood that I covered in velvet, and then used an upholstery stapler to attach the velvet on the back. They were then screwed to the wall. So, no warping or problems there. But here - I can't "screw" the floor panels to anything - so using MDF is a better idea in regards to a "level" looking mass. 

Curious on the sound change. Otherwise, I might just be better getting a black rug.


----------



## carp

Scotty,

I used two long strips of trim moulding that I cut to fit the width of my room, one of them under the screen and the other around 6 feet away from the screen and then stapled the velvet to the strips and pulled it tight. The trim piece gives the edge a nice perfect straight line. Looks great even under bright light and when I have (or had before covid) gatherings I just roll up the moulding bringing it close to the screen to make room for beanbags and kids on the floor. Rolled up it still looks great and blends in, so basically I can cover as much carpet as I want from nothing up to 6 ish feet depending on how much I roll the wood trim piece.


----------



## carp




----------



## ScottieBoysName

carp said:


> View attachment 3070095
> 
> 
> Scotty,
> 
> I used two long strips of trim moulding that I cut to fit the width of my room, one of them under the screen and the other around 6 feet away from the screen and then stapled the velvet to the strips and pulled it tight. The trim piece gives the edge a nice perfect straight line. Looks great even under bright light and when I have (or had before covid) gatherings I just roll up the moulding bringing it close to the screen to make room for beanbags and kids on the floor. Rolled up it still looks great and blends in, so basically I can cover as much carpet as I want from nothing up to 6 ish feet depending on how much I roll the wood trim piece.


This is a GREAT idea! I’ll work on this. Did the rug thing first. Worked out alright.


----------



## carp

Looks really good as is, love the JTR's!


----------



## ScottieBoysName

carp said:


> Looks really good as is, love the JTR's!


Thanks! Your black hole scenario you have going on there is epic - hope I can get there someday.


----------



## jdlynch

I'm in the process of determining what approach to take for room treatments in my theater. Bass trapping in the corners will be my first step.

Right now, my entire front wall, and 6' back on the side walls and ceiling are covered in velvet. I love the feeling of the screen seeming to float in space and don't want to lose that effect.

My question is in regards to corner bass traps; can they be covered in black velvet fabric? I'm not sure how the standard black or GOM materials would look against the black velvet.

Shout out to @ereed for his advice and guidance in REW and room treatments in general.


----------



## anjunadeep

jdlynch said:


> I'm in the process of determining what approach to take for room treatments in my theater. Bass trapping in the corners will be my first step.
> 
> Right now, my entire front wall, and 6' back on the side walls and ceiling are covered in velvet. I love the feeling of the screen seeming to float in space and don't want to lose that effect.
> 
> My question is in regards to corner bass traps; can they be covered in black velvet fabric? I'm not sure how the standard black or GOM materials would look against the black velvet.
> 
> Shout out to @ereed for his advice and guidance in REW and room treatments in general.


Standard black velvet won't be, but there might be some acoustical velvet. If you can breath through it without much resistance, it's good.


----------



## lmidgitd

If they are only bass traps, wouldn't the waves pass straight through the velvet at those lower frequencies?


----------



## ereed

jdlynch said:


> I'm in the process of determining what approach to take for room treatments in my theater. Bass trapping in the corners will be my first step.
> 
> Right now, my entire front wall, and 6' back on the side walls and ceiling are covered in velvet. I love the feeling of the screen seeming to float in space and don't want to lose that effect.
> 
> My question is in regards to corner bass traps; can they be covered in black velvet fabric? I'm not sure how the standard black or GOM materials would look against the black velvet.
> 
> Shout out to @ereed for his advice and guidance in REW and room treatments in general.


While the GOM is acoustic transparent and are black enough, its not as black as velvet but being on the front wall in the dark you won't even notice it. You can cover the bass traps with velvet if you want, it won't affect the bass at all. I have the GIK soffits in GOM black and here it is with lights on and camera flash and without flash which you can't see it.


----------



## anjunadeep

lmidgitd said:


> If they are only bass traps, wouldn't the waves pass straight through the velvet at those lower frequencies?


Ah yeah. I wrongly assumed you still wanted to use them for broadband absorption as well. The tuned absorbers essentially have a membrane on them.


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## lmidgitd

Granted you are correct, they will reflect the higher frequencies. I haven't seen anyone wrap a bass absorber in a non acoustic fabric.


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## Harkon

I’m building soffits/tray ceiling in my room. The plan was to finish the soffits with two layers of MDF and Green Glue. This was to reduce noise transmission through the ducting to the next room, as well as reduce the noise from the inline fans that will be in the soffit. All soffits will be filled with pink fluffy. 

I’m having second thoughts about the two soffit sections on the back wall, either side of the projector. I could leave MDF on the bottom but make the side panels out of black acoustically transparent fabric. Wondered if this would act as a large absorber? It would be 1ft high x 2ft deep and about 4ft wide.

I could even cut out sections of the MDF underside and cover with cloth...


----------



## bommai

My son and I are new to REW. I have played around with it before but not in a serious way. My son is doing a science project on the whole room treatment issue (for his 8th grade science research class). I am attaching the data file to this post. His project scope is to see how treating first reflection points help with sound quality. We have a center channel speaker that we are trying to test with. We are using a 2014 Mac Mini running Big Sur OS and latest version of REW (5.20 beta 61) connected via HDMI to a Denon x4300h receiver. We are using a JBL 530 book shelf speaker as a center channel on a stand. We are using a Umik-1 as microphone with the calibration file loaded. We are using Measure and setting the signal level as 80dB (by adjusting the volume on the denon). Then start measurement. We are using Pure Direct on the Denon so it does not perform any bass management or any eq (I hope that is a correct assumption). We took 10 measurements back to back with a frequency sweep of 80-20kHz. We did an average after that. We saved off that result. Then we repeated that by adding a 2" compressed fiberglass panel treatment to the left and right wall where the first reflection point is for the center channel speaker. We also repeated with 4" compressed fiberglass panels instead of 2". Then we used 2" mineral wool (rockwool) panels, then 4" rockwool panels, Then the loose fiberglass batting as treatment. We are limiting our project to treating first reflection points. We did not treat the ceiling because it was too hard to do! We thought something would look better with the treatment but as you can see from the attached data files, nothing looks that great. He is having trouble writing his conclusion for his project. Yikes. Any ideas.

To make matters worse, I accidentally broke the UMik-1 by trying to reseat a loose tip and the wire came apart  Luckily we have already collected the data but we won't be able to collect anymore!

Thanks!

REW_Data


----------



## Mashie Saldana

Harkon said:


> I’m building soffits/tray ceiling in my room. The plan was to finish the soffits with two layers of MDF and Green Glue. This was to reduce noise transmission through the ducting to the next room, as well as reduce the noise from the inline fans that will be in the soffit. All soffits will be filled with pink fluffy.
> 
> I’m having second thoughts about the two soffit sections on the back wall, either side of the projector. I could leave MDF on the bottom but make the side panels out of black acoustically transparent fabric. Wondered if this would act as a large absorber? It would be 1ft high x 2ft deep and about 4ft wide.
> 
> I could even cut out sections of the MDF underside and cover with cloth...


Soffits are great for bass traps, I have them all around the perimiter of my room with with fabric on all surfaces.


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## harrisu

Hi guys. I want to build a panel that absorbs low frequency for dialog clarity and reflects high ones. I think if I install a thin plywood inside the panel followed by 703 corning material, it will reflect high frequency and absorb the lower ones. Is my understanding correct?


----------



## Mashie Saldana

harrisu said:


> Hi guys. I want to build a panel that absorbs low frequency for dialog clarity and reflects high ones. I think if I install a thin plywood inside the panel followed by 703 corning material, it will reflect high frequency and absorb the lower ones. Is my understanding correct?


It is even easier than that, just get the 703 FRK and have the FRK face the room, no need for plywood.


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## harrisu

Mashie Saldana said:


> It is even easier than that, just get the 703 FRK and have the FRK face the room, no need for plywood.


I have FRK but its very reflective and one can easily see thru the acoustic cloth. I also have this paper that is black and not visible at all. I tried paper but on my listening session, I felt like there was more absorption going on. May be I'm wrong and the paper should be enough to reflect high frequencies? In summary
1 - FRK very visible
2 - Paper didn't seem to reflect as much
3 - Plywood: I already have at home and won't take too much of time to cut to fit with my circular saw.

But I'd go with what's most effective. Are all three options equally effective? FRK is a very shiny paper though so not sure what to do with that shininess.


----------



## Mashie Saldana

harrisu said:


> I have FRK but its very reflective and one can easily see thru the acoustic cloth. I also have this paper that is black and not visible at all. I tried paper but on my listening session, I felt like there was more absorption going on. May be I'm wrong and the paper should be enough to reflect high frequencies? In summary
> 1 - FRK very visible
> 2 - Paper didn't seem to reflect as much
> 3 - Plywood: I already have at home and won't take too much of time to cut to fit with my circular saw.
> 
> But I'd go with what's most effective. Are all three options equally effective? FRK is a very shiny paper though so not sure what to do with that shininess.


If you want to try the plywood, take a look at the GIK designs for ideas with their scatter plates.

Personally I simply mixed absorption and diffusion in the first reflection points which pretty much end up being the entire walls when you have an immersive speaker layout.


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## harrisu

Mashie Saldana said:


> If you want to try the plywood, take a look at the GIK designs for ideas with their scatter plates.
> 
> Personally I simply mixed absorption and diffusion in the first reflection points which pretty much end up being the entire walls when you have an immersive speaker layout.


I also have a mix of absorption and diffusions on my walls. In fact, I am using 12"x12" patter. So 12"x12" absorber followed by 12"x12 diffuser. This allows me to create a Mirror patter on the opposite side. I also have same on my ceiling b/w MLP and on top of MLP. So I'm doing this already  and may I say very effectively. @carp and I have been exchanging ideas as well. The only issue I faced was that I felt like I was having just a little bit of difficulty in certain cases understanding dialog. I know what part of room is causing it. Its 2nd reflection contralateral point on side wall. If I leave it untreated, room sounds very open (which I like) but if I put absorber, it takes away this open sound a bit. If I put diffuser, it doesn't solve the issue with dialog clarity. So the solution is simple: Absorb low frequency and reflect (not diffuse) high frequency. Therefore, I wanted to use a thin plywood, paint it black and put inside the panel. Then put 2" or 4" 703 to absorb the 100Hz-600Hz frequencies. That's where dialog reside.


----------



## Mashie Saldana

harrisu said:


> I also have a mix of absorption and diffusions on my walls. In fact, I am using 12"x12" patter. So 12"x12" absorber followed by 12"x12 diffuser. This allows me to create a Mirror patter on the opposite side. I also have same on my ceiling b/w MLP and on top of MLP. So I'm doing this already  and may I say very effectively. @carp and I have been exchanging ideas as well. The only issue I faced was that I felt like I was having just a little bit of difficulty in certain cases understanding dialog. I know what part of room is causing it. Its 2nd reflection contralateral point on side wall. If I leave it untreated, room sounds very open (which I like) but if I put absorber, it takes away this open sound a bit. If I put diffuser, it doesn't solve the issue with dialog clarity. So the solution is simple: Absorb low frequency and reflect (not diffuse) high frequency. Therefore, I wanted to use a thin plywood, paint it black and put inside the panel. Then put 2" or 4" 703 to absorb the 100Hz-600Hz frequencies. That's where dialog reside.


Give it a try and let us know how it works.


----------



## Technology3456

I need to treat my room to make it dark, and was told to use velvet. Is there a material that will accomplish making it dark but also acoustic treatment all in one material?


----------



## Mashie Saldana

Technology3456 said:


> I need to treat my room to make it dark, and was told to use velvet. Is there a material that will accomplish making it dark but also acoustic treatment all in one material?


No, when you see rooms with just fabric walls then there are sound treatments behind the fabric.


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## AndreNewman

Currently my 3.5m screen is directly screwed to the wall behind, I recently moved my projector back into the room behind so I'm considering putting some treatment on the wall behind the screen now that the throw allows.

It would be fairly easy to do 100mm rockwool behind the screen 3.5m x 1.5m, 200mm would be much more difficult so I'm wondering if 100mm would still be beneficial. I already have 3x 300mm bass traps to left right and below the screen,500x300mm above. The whole front wall would be either 100mm behind the screen or 300mm deep bass trap.

I'm planning 300x450mm vertical bass traps for the back of the room but I really can't work out how to treat the back wall beyond the heavy velvet curtains we have already.

I'm hoping for some improvement to the messy 80Hz to 200Hz region.

Any thoughts, comments?


----------



## Technology3456

For USA what are some of the best websites to look for black velvet to put on ceiling, and velvet curtains about 10 feet by 8 feet? Accessoriesforless? I only know where to buy TVs and speakers, I've never bought room treatment stuff before.


----------



## knowlesm

Technology3456 said:


> For USA what are some of the best websites to look for black velvet to put on ceiling, and velvet curtains about 10 feet by 8 feet? Accessoriesforless? I only know where to buy TVs and speakers, I've never bought room treatment stuff before.


You probably have a local Joann's (link below) and can just pick it up. Never pay full price here, either. There is almost always a 25%+ off coupon you can find online.






Royalty 3 Velvet


44'' Wide. 36% Nylon 64% Acetat. Dry Clean Only.




www.joann.com


----------



## howiee

carp said:


> View attachment 3070095
> 
> 
> Scotty,
> 
> I used two long strips of trim moulding that I cut to fit the width of my room, one of them under the screen and the other around 6 feet away from the screen and then stapled the velvet to the strips and pulled it tight. The trim piece gives the edge a nice perfect straight line. Looks great even under bright light and when I have (or had before covid) gatherings I just roll up the moulding bringing it close to the screen to make room for beanbags and kids on the floor. Rolled up it still looks great and blends in, so basically I can cover as much carpet as I want from nothing up to 6 ish feet depending on how much I roll the wood trim piece.


That is genius! Is the trim moulding at the screen end fixed in anyway? If you don't mind me asking - what method did you use for the walls and ceiling too?


----------



## carp

howiee said:


> That is genius! Is the trim moulding at the screen end fixed in anyway? If you don't mind me asking - what method did you use for the walls and ceiling too?


Thanks howiee, 

I used 2 strips of molding. One of them on the screen end, and the other on the far end, both run the width of the room. The strip on the screen end is always in the same place and rests up against the velvet that was already on the screen wall so you can't tell that there is any separation, it looks like continuous black. 

As far as the walls and ceiling go I just stapled the JoAnn velvet. For the ceiling I found that it was easier to initially use tacks to get/hold it in place and then I held/stretched it tighter and stapled it into the ceiling. At first I tried using a sharpie on the staples but I found that using a flat black spray paint on the staples, letting them dry, and then loading them into the stapler worked better to hide the staples.


----------



## kalakasan

After diving into the acoustic treatment rabbit hole, I'm beginning to reconsider applying a chair rail on my theater walls, because of the requirement for panels to be placed at the listening level.

Has anyone come to this same decision point in their application of acoustic treatments? Mine is not a full-blown theater room (low ceilings and 85" tv), but audio is huge for me and if I had to choose between room aesthetics and great sound, well great sound will win every time. 

So if acoustic panels need to sit lower on the wall, it seems chair rail would get in the way - panels in front of chair rail would break up and ruin the look. Is there a possible compromise here I'm missing? Will panels just above the chair rail still be effective?









Thanks!


----------



## pkinneb

kalakasan said:


> After diving into the acoustic treatment rabbit hole, I'm beginning to reconsider applying a chair rail on my theater walls, because of the requirement for panels to be placed at the listening level.
> 
> Has anyone come to this same decision point in their application of acoustic treatments? Mine is not a full-blown theater room (low ceilings and 85" tv), but audio is huge for me and if I had to choose between room aesthetics and great sound, well great sound will win every time.
> 
> So if acoustic panels need to sit lower on the wall, it seems chair rail would get in the way - panels in front of chair rail would break up and ruin the look. Is there a possible compromise here I'm missing? Will panels just above the chair rail still be effective?
> 
> View attachment 3084304
> 
> Thanks!


Couldn't you either cut the chair rail out where needed so it comes up to panel or maybe easier just cut the panel to wrap around the chair rail?


----------



## AndreNewman

kalakasan said:


> After diving into the acoustic treatment rabbit hole, I'm beginning to reconsider applying a chair rail on my theater walls, because of the requirement for panels to be placed at the listening level.
> 
> Has anyone come to this same decision point in their application of acoustic treatments? Mine is not a full-blown theater room (low ceilings and 85" tv), but audio is huge for me and if I had to choose between room aesthetics and great sound, well great sound will win every time.
> 
> So if acoustic panels need to sit lower on the wall, it seems chair rail would get in the way - panels in front of chair rail would break up and ruin the look. Is there a possible compromise here I'm missing? Will panels just above the chair rail still be effective?
> 
> View attachment 3084304
> 
> Thanks!


Panels need to be put where they need to be... I'm discovering for myself that if they aren't big enough for the frequency you want to treat they don't do anything, if you put them in the wrong place, they don't do anything. Well they probably do something but not what you had planned.

You get better performance when there is a gap behind the panel anyway so just fit them in the correct places and have an air gap big enough to clear the rail behind the panel.


----------



## kgveteran

Use 4” ridged OC703, you’ll be fine, find the exact point ghey hit the wall and center a panel there. Air gaps are fine, but why air gap when 4” OC is possible :0)
You are on point, do t compromise acoustics for cosmetics. Parallel walls that are not part of your First reflection points should get some diffusers too.
Bottom line ALL rectangle rooms stink, no exeption to that rule. Oh, you can decide not to treat a room, we have many customers who decide not to.....thats their call


----------



## Everyone

Would sandwiching black velvet between two pieces of OC 703 have a negative effect on the acoustic panel? 

I want to wrap my walls and ceiling in black velvet, but since it's not an AT fabric, I plan to use a different fabric for the acoustic panels. I was going to use 1" thick furring strips to build frames for the black velvet wall panels. Want to make it as seamless as possible. I thought maybe I could put 1" thick OC 703 as a backer behind the black velvet where an AT panel will go, then add a 1" or 2" thick OC 703 wrapped in an AT material on top of it. 

Not sure if this would help, hurt, or just be a waste? 

Would I be better off just putting extra furring strips behind the black velvet in areas where an acoustic panel will be mounted?


----------



## kalakasan

kgveteran said:


> Use 4” ridged OC703, you’ll be fine, find the exact point ghey hit the wall and center a panel there. Air gaps are fine, but why air gap when 4” OC is possible :0)
> You are on point, do t compromise acoustics for cosmetics. Parallel walls that are not part of your First reflection points should get some diffusers too.
> Bottom line ALL rectangle rooms stink, no exeption to that rule. Oh, you can decide not to treat a room, we have many customers who decide not to.....thats their call


Thanks for the reply. The question that remains is can I get away with not placing panels below the chair rail? The rails are drawn to be about 30 inches above the floor. If that’s too much of a compromise on potential sound quality, I’ll forgo it.


----------



## sdurani

Everyone said:


> Would sandwiching black velvet between two pieces of OC 703 have a negative effect on the acoustic panel?


Try blowing air through the black velvet. If you can easily blow through it, then it won't impact how well the panel works. If you pass out trying to blow air through it, don't use the fabric.


----------



## PaulF757

Would placing an acoustic panel over my in wall rear surrounds impact the sound quality enough to notice it? My reasoning is to keep asymmetry in the back wall with my panels. The plan is to cut out the insulation where the speaker is.

Appreciate the feedback.


----------



## Pretorian

*BACKGROUND*
I have my own home cinema that I love. I constantly change things (small or big) and try to improve it. 
I have, for a long time, been thinking of beginning with acoustical treatments but I have a hard time finding out what do to as the first step?
I think I need some help.

*PROBLEM*
Another thing is that as of lately I have been feeling some "fatigue" when listening to both music AND watching movies. I dont even have to play that loud.
The bass sometimes feels as if I sit in a bubble and I can feel my ears vibrate (again, not any loud music) and I almost get sick.
I get almost the same feeling when playing music or movies with parts that dont have that much bass. It can be just a conversation in a movie.
This has happened lately without any special change in my room so I am not sure if it has to do with something else or that I am more sensitive (older?).



*Here is my room and equipment:*

Width: 14.4 feet (440 cm)
Depth: 12.1 feet (370 cm)

PROJECTOR
- Epson 9400 / Epson 6050 

SCREEN
- Euroscreen 104" 16:9 Grey High Contrast ReAct Fixed Screen

SOURCES
- Dune HD Pro 4K
- Panasonic Blu-Ray Player
- Xbox One X 

AMPLIFICATION
- Denon AVR-X4500 

POWER AMPS
- Rotel RB-970BX
- Rotel RB-970BX II
- Rotel RB-850 

SPEAKERS
- Front (x2): Bowers & Wilkins CDM7 SE
- Centre (x1): Bowers & Wilkins CDMC SE
- Surround (x2): Audio Pro Bipole
- Surround Back (x2): Bowers & Wilkins CDM1 SE
- Atmos (x4): Bowers & Wilkins M1
- Sub (x1): Paradigm PS-1200


----------



## AndreNewman

Pretorian said:


> *PROBLEM*
> Another thing is that as of lately I have been feeling some "fatigue" when listening to both music AND watching movies. I dont even have to play that loud.


If I remove the bass traps and panels from my room I find the sound extremely fatiguing and unpleasant. We moved a couple of bass traps out for a couple of hours to do something with the curtains and even talking in the room was far less pleasant than normal.

Acoustic treatment is the best value for money tweak you can do in my opinion.

I'm hardly an expert but those front corners in your photo are screaming out to me for a couple of floor to ceiling bass traps!  Bigger the better with your room size but 400mm x 400mm (16" x 16") is a common size and should be useful down to 40Hz according to Blue Frog Audio.


----------



## freedomgli

kalakasan said:


> After diving into the acoustic treatment rabbit hole, I'm beginning to reconsider applying a chair rail on my theater walls, because of the requirement for panels to be placed at the listening level.
> 
> Has anyone come to this same decision point in their application of acoustic treatments? Mine is not a full-blown theater room (low ceilings and 85" tv), but audio is huge for me and if I had to choose between room aesthetics and great sound, well great sound will win every time.
> 
> So if acoustic panels need to sit lower on the wall, it seems chair rail would get in the way - panels in front of chair rail would break up and ruin the look. Is there a possible compromise here I'm missing? Will panels just above the chair rail still be effective?
> 
> View attachment 3084304
> 
> Thanks!


I struggle with this also. My room has a very tall chair rail trim that practically bisects the side wall height wise. Underneath is beadboard wainscoting and above is sheetrock. It is the bane of my music room but I don’t have money to extensively remodel. So my decision was to use a mix of portable freestanding 244 bass traps and a mix of 242 panels and Monster traps hung on the walls. They go where they need to go, aesthetics be damned. The 244 bass traps at first reflections have an extra 1.5” air gap because of the chair rail trim. 

When I build a house from scratch I’ll build the ultimate room. Until then, I work with what I’ve got.


----------



## Pretorian

AndreNewman said:


> If I remove the bass traps and panels from my room I find the sound extremely fatiguing and unpleasant. We moved a couple of bass traps out for a couple of hours to do something with the curtains and even talking in the room was far less pleasant than normal.
> 
> Acoustic treatment is the best value for money tweak you can do in my opinion.
> 
> I'm hardly an expert but those front corners in your photo are screaming out to me for a couple of floor to ceiling bass traps!  Bigger the better with your room size but 400mm x 400mm (16" x 16") is a common size and should be useful down to 40Hz according to Blue Frog Audio.


Well thank you. So to kick things off and take it step by step, is this something I can start with and then move forward with some more DIY panels on the walls to reduce the reflections?


----------



## AndreNewman

I did this last weekend:


































I was considering panels across the corners as it's less intrusive but I was concerned that they wouldn't do enough and I'd be forever wondering. With this the curtains mostly disappear behind the traps, I have to do measurements this weekend to see how much difference it made but it sounds significantly better. 

We already have two similar in the front corners and I built what I call my soundbar for the front floor "corner" which is also a mount for the center speaker. This idea might work for your room too:

Mk1, angled panels with speaker integrated:










Mk II "Soundbar"


----------



## Everyone

If the same absorption materials were used (i.e. 4" thick Roxul), would there be any downside to building an L shaped bass trap instead of the usual triangle?


----------



## AndreNewman

Everyone said:


> If the same absorption materials were used (i.e. 4" thick Roxul), would there be any downside to building an L shaped bass trap instead of the usual triangle?


As I understand the important thing is the depth of material the sound has to pass through before it bounces off the wall. The panel across the corner or triangular trap is a way to make it look like more material to the sound wave than a panel flat on the wall. Having an air gap behind the panel helps a little, not as much as a thicker panel but some. I think a L shaped panel is the same as two flat panels on the wall so the performance would be the same.

When I built my first 4" thick panels I got told off in here for calling them bass traps, not thick enough to be worthy of the name apparently.

My latest traps are four layers of 4 inch thick and the smaller 3 layer ones I built last year definitely work. I'm about to go measure these new ones but they immediately, noticeably change the sound in the room so I think the measurements will show a benefit.

Blue Frog Audio are useful because they publish easy to follow specs for their panels, I'm assuming mine will work similarly if they are the same size, I hope... I use the same Knauf insulation that they do and the same wood, probably.

So their BF125 5" panel works down to 80Hz (It's 4" insulation and a 1" air gap).
The BF4040 that I based my traps on works down to 40Hz.
The BF612 is a BF4040 sliced diagonally and they say works down to 50Hz.

So I'm thinking that a 4" L panel will work down to 80Hz, they don't say if the BF125 works lower if it's across a corner.

Earlier you said Velvet isn't acoustically transparent, the Whaley's devore I'm using mostly is, I measured it before starting to build panels, It's more transparent than my speaker grilles anyway.


----------



## Everyone

AndreNewman said:


> When I built my first 4" thick panels I got told off in here for calling them bass traps, not thick enough to be worthy of the name apparently.


Interesting since that's the thickness most places selling pre-built ones sell them in.



AndreNewman said:


> Earlier you said Velvet isn't acoustically transparent, the Whaley's devore I'm using mostly is, I measured it before starting to build panels, It's more transparent than my speaker grilles anyway.


Well the cheaper Velvet I'm looking at doesn't seem to be very acoustically transparent anyway. At least not compared to the other fabric samples I have that are marketed as AT fabrics. I couldn't find a source for the Whaley's Devore in the US.


----------



## Technology3456

Guys for a 10 foot wide space with 8 foot ceilings, I dont exactly have an amphitheater room here, do you think I would be better off with blackout curtains on my walls and ceiling that totally dampen sound, so that I am not getting sound reflection in a small cube like space that probably would not give that good big theater sound, or does the fact it's already small and cube like mean I want to maintain as much reflectivity as possible, and get curtains that dont dampen things further?


----------



## T-Bone

Technology3456 said:


> Guys for a 10 foot wide space with 8 foot ceilings, I dont exactly have an amphitheater room here, do you think I would be better off with blackout curtains on my walls and ceiling that totally dampen sound, so that I am not getting sound reflection in a small cube like space that probably would not give that good big theater sound, or does the fact it's already small and cube like mean I want to maintain as much reflectivity as possible, and get curtains that dont dampen things further?


You did not get any of the valuable information from this thread. I suggest you go back and reread. 

Blackout curtains alone does not dampen sound to any significant degree. This thread is focused on treatments (in other words, usually it refers to the material _behind_ the fabric).

-T


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## Technology3456

T-Bone said:


> You did not get any of the valuable information from this thread. I suggest you go back and reread.
> 
> Blackout curtains alone does not dampen sound to any significant degree. This thread is focused on treatments (in other words, usually it refers to the material _behind_ the fabric).
> 
> -T


I have been reading the blackout thread, where a user mentioned he is going with Devore fabric, instead of Fidelio black velvet or SY triple black velvet, despite Devore not being quite as black and light resistant, because he didn't want to dampen the sound of his room as much as the thicker Fidelio and SY Triple black fabrics would do.

For his room, he feels less dampening fabric would be a good thing.

But his room is not my room. So I came here to ask whether my room would benefit from dampening fabrics, like Fidelio or SY Triple black, unlike his room, or if my room would also benefit from thinner fabrics like Devore, like his room does.

I have been following both threads. I wasn't sure with the last question about the shelves, what thread to post in, but for this question I am positive, this is the right thread. If you or anyone else knows the answer to the question for a room like mine, I'd appreciate any advice because I would like to get the order in ASAP but until I know whether to target less dampening, or more dampening, curtains for my room, I cannot choose. If it was just about which was blackest, I would pick Fidelio or SY, but the other poster's post about Devore and his explanation enlightened me that I also need to ask about this consideration before deciding.

Ty everyone for the help!


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## harrisu

Got an interesting question for you guys. My system is a 7.4.4. I'll show Left and Right walls of my HT. Not showing ceiling but 1st reflection on ceiling is covered with 4" for Center and diffusers for L/R. There is treatment on ceiling above MLP as well as a mixture of diffusers/absorbers in checker pattern. 

Question: In the images you can see that I have two abosorbers covered with a black paper. That's the 1st reflective point for Center speaker. All abosorbers are 4" thick 703 so they should go down to 100Hz and absorb 100% up to that frequency. Without papers on, I get very clear dialogs. I added paper to reflect the high frequencies. Without papers, room sounded good but with papers on, I get more dynamic effects. It also made room sound bigger.
So far so good. If I add paper to another absorber, it starts making the dialog a bit less clear (female vocal specifically). I get more dynamics which I like and I also like how there is a balance b/w the sound stage in front of me and behind me. What I'm confused about is that paper should only reflect high frequencies and lower frequencies should be absorbed by 12"x12". In other words, adding paper shouldn't cause vocals to get a bit blurrier since dialogs reside b/w 100Hz-1000Hz. Therefore, adding paper really shouldn't cause any issue with dialog clarity. So then Why is that happening? Did I misunderstand anything here? I can post all the pics of room if it helps to get to the bottom of this.
I remember @sdurani mentioned that he likes his center 1st reflection reflective and after this experiment I can also tell that having my center speaker reflect high frequencies gives my dynamic experience. 
FYI: to test dynamic effects, I play different movie trailers. Trailers have great dynamics generally and are good way to test. 
Note: if you pay close attention, you'll see that Left side doesn't mirror Right side. Where there is an absorber on left wall, right wall has diffuser and vice versa.


Right Side Wall










Left Side Wall


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## doozer12

Is there an acceptance way to paint burlap so it doesnt change the properties of the fabric? My thought is that spray pInt mY be ok as long as it doesnt close the holes in the fabric.. Would it make it too reflective?


Sent from my iPhone using Tapatalk


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## sdurani

doozer12 said:


> Is there an acceptance way to paint burlap so it doesnt change the properties of the fabric?


Dye the fabric instead of painting it.


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## AXLCMT

Any ideas how this company is able to seemingly "glue" the acoustical fabric to the back of the panel and onto the yellow OC703? It looks like they took a clothing iron and flattened it completely
onto the back of the panel. 




Also, how do they permanently attach the OC703 so snuggly and permanently? 
My OC703 filled fabric panels are designed so the OC703 is friction fitted but it still pops out if I remove my fabric panels.

How do you permanently install OC703 like they did in this link? Glue the sides to the fabric panel inside edges?


----------



## Everyone

AXLCMT said:


> Any ideas how this company is able to seemingly "glue" the acoustical fabric to the back of the panel and onto the yellow OC703? It looks like they took a clothing iron and flattened it completely


Might be using something like this? No-Frame Edge Coating (metroflexsound.com)


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## Pretorian

Can I use my Denon X4500 and the Audyssey app to measure my room? Is that called REW?
Will that help me on how where and what kind of treatment my room needs?
Or am I simplifying things a little?


----------



## wpbpete

Pretorian said:


> Can I use my Denon X4500 and the Audyssey app to measure my room? Is that called REW?
> Will that help me on how where and what kind of treatment my room needs?
> Or am I simplifying things a little?


Hey, REW is for measuring ie: shows you graphs etc... Audsy will apply the changes, that you can then see in REW. You need to download REW from avnirvana.com and purchase a Umik1. Hope that helps.


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## Pretorian

wpbpete said:


> Hey, REW is for measuring ie: shows you graphs etc... Audsy will apply the changes, that you can then see in REW. You need to download REW from avnirvana.com and purchase a Umik1. Hope that helps.


Got it! Is there a guide for the REW that is good for beginners?


----------



## rec head

REW Thread


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## nathan_h

Several searches have yielded mentions of DIY scatter plate designs (for placing in front on a DIY absorption panel made of OC703) but so far I haven't seen anyone with data about what kind of dimensions the openings should be. 

I'm trying to keep it simple. Was planning to use a router to cut out long slats from a 1/8th inch piece of plywood that will go in front of the fiberglass.

Any proven design principles I should follow? Like, 1/2” openings separated by 1/2” of solid material, or something like that? I would guess the math is pretty definitive about the size of the openings to allow absorption of (for example) the full vocal range, while reflecting stuff above that range? Or maybe there is a mathematical pattern that indicates the sizes should change?


----------



## Phytonic13

I have a massive boundary gain from the right tower. What could be done to tone down the bass response ?


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## nathan_h

Phytonic13 said:


> I have a massive boundary gain from the right tower. What could be done to tone down the bass response ?


The photos are dark. Is the construction different on each side of the room?


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## Phytonic13

nathan_h said:


> The photos are dark. Is the construction different on each side of the room?


Yeah. The room is completely blacked out. The right is next to walls. The left is more open and does not have the massive bass response. It really screws with the sound and ear pressure. Just want to tame the right.


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## nathan_h

Thats interesting.

Well the bass should be coming from the sub(s) and not the mains.

But if you are still getting boundary reinforcement on one speaker, even with proper bass management, I would use eq on the speaker.

IIRC trying to trap the problematic frequencies with tuned traps will impact all the speakers not just one.

Here more info about using EQ to counteract excess bass from placement near a boundary The #1 Speaker Placement Tip That Speaker Manuals Get Completely Wrong — SonicScoop











The other issue you may be hearing from the proximity of the wall is SBIR. This one is relatively easy to solve since if you keep the speaker within 3 feet of the wall, all the SBIR is above 100hz — the closer to the wall, the higher and the easier it is to absorb with acoustic absorption between speaker and wall.


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## Pretorian

I have been in contact with GIK Acoustics since I am not sure I have the time or skill to build basstraps and panels DIY.
Do you have any recommendations OR warnings when it comes to GIK? 

For my room I was recommended this kit:








GIK Acoustics Room Kit Package #4 - GIK Acoustics Europe


GIK Acoustics offers 4 economical and ideal room kits with bass traps and acoustic panels to address room acoustic issues that fit within your budget.




gikacoustics.eu





I also got detailed comments on how to place and where. 

Here is the room (I have posted this before)


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## nathan_h

That is good advice. You will be very happy with the impact!

--

Personally, if you need to save money, the corner bass traps are nice to have, but if you are able to position the sub and seats well, you can control bass peaks with EQ, so you could save money not getting the corner traps yet and still get decent results. (This assumes you are running your speakers as "small" and sending all bass to the sub(S)).

And I would want one or two more Monster Bass Traps on the wall behind my head. That is a great place to put several such thick panels. (I would prefer those additional on wall thick panels behind my seating area instead of corner traps, if I had to choose one or the other -- though getting both with be ideal.)

Oh, and the position of the front wall panels should be directly behind the speakers. These are not for early reflections but instead for controlling SBIR. (I mention this because their diagram doesn't make that clear.)


----------



## Pretorian

nathan_h said:


> That is good advice. You will be very happy with the impact!
> 
> --
> 
> Personally, if you need to save money, the corner bass traps are nice to have, but if you are able to position the sub and seats well, you can control bass peaks with EQ, so you could save money not getting the corner traps yet and still get decent results. (This assumes you are running your speakers as "small" and sending all bass to the sub(S)).
> 
> And I would want one or two more Monster Bass Traps on the wall behind my head. That is a great place to put several such thick panels. (I would prefer those additional on wall thick panels behind my seating area instead of corner traps, if I had to choose one or the other -- though getting both with be ideal.)
> 
> Oh, and the position of the front wall panels should be directly behind the speakers. These are not for early reflections but instead for controlling SBIR. (I mention this because their diagram doesn't make that clear.)


Thank you! That is good input.

GIK recommended me to put TWO wall panels on each side of the front speakers... he never mentioned anything behind my fronts. And I plan on upgrading to a wider screen that will runt behind each speaker so I will not have much room for a panel.


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## nathan_h

Yeah the front wall panels are nice to have but not nearly as important as the back and side walls.


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## Pretorian

nathan_h said:


> Yeah the front wall panels are nice to have but not nearly as important as the back and side walls.


Would you recommend that I add another TWO Monster Bass Traps 1200x600 for my back wall? If you look at my video you can see that there is a wide opening on the back wall. I can put a bass trap floor standing in front of the opening.


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## nathan_h

Hard to fit much more than one back there, I guess? Now that I see the space, and visually estimate the size of the wall, three wouldn't physically fit, I am guessing.

Side wall with the window will also make it challenging to place a panel there....did Gik have ideas about what to do with the side walls?


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## marjen

Looking for feedback and assistance with my room. A little background. Finished building the house about 18 months ago. My old house had a basement theater, I decided I wanted to move my media room to the first floor. This creates a couple new issues I did not have to deal with before, a large window and sound containment.

Right now I want to focus on the sound properties and work to dial in where and how to treat the room, and decid if I need to move the L and R fronts to the corners. The sound leak issue is mostly due to a barn door, I need to do something better with the door and I think it would reduce sound leak. The room has an extra 2x4 wall along the side with the door, this was needed to accommodate dCut work. It’s filled with Roxul safe and sound R30. I used 5/8 sheet rock in the theater. The room is 17x13 ft 4in. There is a false wall 22” from the front. So about 15’ of actual room length To play with.

Gear: JBL Studio 590 for L,C,R. JBL 530 for side and back surrounds. I currently have 2 atmos ceiling speakers and plan on getting 2 more eventually. Sub is currently a single SVS PB-12 NSD. I can on getting a second one someday.

So looking for feedback on where and what to treat in order of importance. I have created a couple panels out of 3” safe and sound roxul. I also just was able to find some Roxul comfortboard 80. I have enough for (12) 2x4 panels. Can buy more if needed. So.

1. Where to treat first? Front wall? Window? Back wall? Reflection points?
2. What should I do with L and R fronts. I thought they should be within the screen but I am seeing some things now that maybe they should be all the way in the corners? They are currently 100” center to center of L and R. My head is about 10’8” from center.
3. Currently have posters on back wall with glass, should those be moved?
4. Should the sub be moved? I can only fit between front speakers if its turned sideways.
5. I have thought about a rood diffuser wall in the back of the room using various depth wood pieces, would that be a good or bad idea?

I am including some pics of the room.


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## Pretorian

nathan_h said:


> Hard to fit much more than one back there, I guess? Now that I see the space, and visually estimate the size of the wall, three wouldn't physically fit, I am guessing.
> 
> Side wall with the window will also make it challenging to place a panel there....did Gik have ideas about what to do with the side walls?


My suggestion for sidewalls is that I put the side panels on stands on both the right and the left wall so it is the same. That way I can put the panels in front of the window. I am waiting for a response from GIK.
What would you say about that suggestion?
Imagine that I will change some things in the room. I will remove all the sideboards and things on the left side so it will just be a wall. And I will place the sofa center in front of the screen so it will get more symetrical.
I will install a dark/black full cover carpet all over the floor.
And, as I said, I will put two panels on each side of the front speakers on stands.


----------



## nathan_h

Pretorian said:


> My suggestion for sidewalls is that I put the side panels on stands on both the right and the left wall so it is the same. That way I can put the panels in front of the window. I am waiting for a response from GIK.
> What would you say about that suggestion?
> Imagine that I will change some things in the room. I will remove all the sideboards and things on the left side so it will just be a wall. And I will place the sofa center in front of the screen so it will get more symetrical.
> I will install a dark/black full cover carpet all over the floor.
> And, as I said, I will put two panels on each side of the front speakers on stands.


Yeah if you are okay with panels on stands blocking the window that is likely a very good choice.


----------



## Pretorian

nathan_h said:


> Yeah if you are okay with panels on stands blocking the window that is likely a very good choice.


I see now that the thinner panels that I will use for first reflection is 2,6 inches. Is that ”enough” thickness for the job?
The bass trap panel for the backwall is 6,5 inches.


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## nathan_h

Hopefully someone with more knowledge that me will weight in. I know that 6" is preferred in order to cover more frequencies more evenly (ie, it gets down lower, so you don't end up deadening the highs without controlling lower frequencies) but:

1) Many people use 4" panels on the side walls (which are often more like 3" of fiberglass and a little air gap) with success, especially with scatter plates on them.

2) Having an air gap behind the panel increases the frequencies that are impacted and since yours will be a couple inches off the side walls (at least on the window side, ideally mirrored on the other side) that may help with impacting some lower frequencies. 

But again, I am not an expert in the math. It would be worth asking GIK about that, for sure, and hopefully someone will weigh in here and educate both of us.


----------



## Pretorian

nathan_h said:


> Hopefully someone with more knowledge that me will weight in. I know that 6" is preferred in order to cover more frequencies more evenly (ie, it gets down lower, so you don't end up deadening the highs without controlling lower frequencies) but:
> 
> 1) Many people use 4" panels on the side walls (which are often more like 3" of fiberglass and a little air gap) with success, especially with scatter plates on them.
> 
> 2) Having an air gap behind the panel increases the frequencies that are impacted and since yours will be a couple inches off the side walls (at least on the window side, ideally mirrored on the other side) that may help with impacting some lower frequencies.
> 
> But again, I am not an expert in the math. It would be worth asking GIK about that, for sure, and hopefully someone will weigh in here and educate both of us.


Here is the answer from GIK. I think the panels will work:


””The thickness needed is more ore less defined by the room dimensions and the wall we are looking at.

For the purpose of covering early reflection points the 242 is absolutely fine in your room 
Thicker panels make sense above yourself or left and right since they would stop or minimise standing waves. 
Also our 242 comes down to 250Hz… that is low enough ””


----------



## nathan_h

Fair enough! Thanks for sharing their response.


----------



## TonyHT

I’m in the process of finishing my basement for a home theater room. I’ve read through some acoustics articles but haven’t come across the answer for my question. Should I completely line the wall behind my front speakers with something like OC705 or 703?

I’ll have three floor standing speakers for the LCR and two 18” subwoofers. I’m going to have floor to ceiling OC705FRK in the corners for bass traps, but I wasn’t sure about everything in between. I wanna say I read somewhere that the wall should be completely treated but I can’t seem to find that answer anymore.


----------



## sdurani

TonyHT said:


> Should I completely line the wall behind my front speakers with something like OC705 or 703?


The most important part of the wall to cover is the space between L/R speakers, to keep the front soundstage from being muddied by reflections AND to minimize boundary cancellation notches in the frequency response. If you want to cover the entire wall, it won't hurt. Make sure the absorption is broadband (6" thick OC703) so that the absorber panels don't end up acting like a tone control by only absorbing higher frequencies.


> I’ll have three floor standing speakers for the LCR and two 18” subwoofers.


If you can, centre the woofers of your L/R speakers 1/6 room width in from the side walls and centre your subs 1/4 room width in from the side walls. Will minimize peaks & nulls created by width modes (resonances), resulting in smoother bass response AND greater seat to seat consistency across the width of your room.


----------



## TonyHT

sdurani said:


> The most important part of the wall to cover is the space between L/R speakers, to keep the front soundstage from being muddied by reflections AND to minimize boundary cancellation notches in the frequency response. If you want to cover the entire wall, it won't hurt. Make sure the absorption is broadband (6" thick OC703) so that the absorber panels don't end up acting like a tone control by only absorbing higher frequencies. If you can, centre the woofers of your L/R speakers 1/6 room width in from the side walls and centre your subs 1/4 room width in from the side walls. Will minimize peaks & nulls created by width modes (resonances), resulting in smoother bass response AND greater seat to seat consistency across the width of your room.


Thanks for the great info! Do they make 6” OC703 or do you double up on 3”?


----------



## sdurani

TonyHT said:


> Do they make 6” OC703 or do you double up on 3”?


I've always bought them in 2" thicknesses and tripled up on them. I'm guessing they come in other thicknesses, but I haven't seen 6" specifically.


----------



## Sands_at_Pier147

4" max for OC703.

"Fiberglas® 700 Series Insulations are available in standard 24"x48" (610mm x 1219mm) boards in thicknesses from 1" (25mm) to 4" (102mm) in 1/2" (13mm) increments."


----------



## harrisu

I want to paint FRK paper with black spray paint. Would like to know if its going to effect its reflectiveness? Its a matte paint. Idea is to make sure the paper doesn't cause any light reflection.


----------



## OJ Bartley

sdurani said:


> The most important part of the wall to cover is the space between L/R speakers, to keep the front soundstage from being muddied by reflections AND to minimize boundary cancellation notches in the frequency response. If you want to cover the entire wall, it won't hurt. Make sure the absorption is broadband (6" thick OC703) so that the absorber panels don't end up acting like a tone control by only absorbing higher frequencies. *If you can, centre the woofers of your L/R speakers 1/6 room width in from the side walls and centre your subs 1/4 room width in from the side walls*. Will minimize peaks & nulls created by width modes (resonances), resulting in smoother bass response AND greater seat to seat consistency across the width of your room.


I'm quoting this so I don't lose it later when I'm setting up my speakers. Thanks Sanjay.


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## sdurani

OJ Bartley said:


> I'm quoting this so I don't lose it later when I'm setting up my speakers. Thanks Sanjay.


You're welcome. Visual representation of placement I was describing: 








Subs in the 2 nulls of the 2nd width mode (black trace). L/C/R speakers in the 3 nulls of the 3rd width mode (red trace). Should reduce/minimize peaks & nulls up to roughly 300Hz across the width of your room. 

Down the road, if you can add a couple of subs to the back wall of your room, you can do similar mode cancelling for your room's length modes.


----------



## pkinneb

harrisu said:


> I want to paint FRK paper with black spray paint. Would like to know if its going to effect its reflectiveness? Its a matte paint. Idea is to make sure the paper doesn't cause any light reflection.


Can't imagine it would but fwiw I have FSK and yellow 703 behind my cloth panels and neither have caused any issues.


----------



## Pretorian

Acoustical beginner here (I will always feel like a beginner). I am about to order my first kit of room treatment from GIK after a long mail correspondance.

I want to find out if I need bass traps (which I do believe i need) and I am trying with a SPL app on my phone to see if it goes up in the two front corners.

How much "should" it go up in terms of decibel? I try a pink noise from Spotify, The app says around 55-58 when I am behind the speaker or on the side and when moving my phone to the bottom corner it goes up to about 62 decibel.

Is this "proof" that Ahaaa! This is where the bass traps should go?


----------



## nathan_h

Bass traps is an interesting phrase. Here is what I have learned:

Room modes can be mitigated a bit with large broad ban absorbers, but not nearly enough. Good subwoofer placement, integration and EQ can do a lot to tame room modes. 

Above the transition frequency, where room modes are less dominant, broad band (ie, thick panel) traps can help but with good speakers (off axis response similar to on axis and on axis respond very linear) you don't need a lot of them to tame the room (perhaps 15% coverage).

This assumes one is using bass management and sending the sub 80hz frequencies to the subs and not the speakers.

Your mains will benefit from being closer to the wall (really as close as possible so that the frequencies are trappable) AND putting six inch thick traps directly behind them. This isn't traditionally calling bass trapping but the impact is that it mitigates SBIR which is bass sounds that wrap around the back of the speaker, bounce off the wall, and mingle in a back way with the direct sound from the speaker. This is the "bass" above 80 hz since the speakers shouldn't be playing much below that.









Speaker Placement 101: Is Speaker-Boundary Interference Killing Your Bass?


Not hearing enough bass through your monitors? The distance between your room boundaries and speakers has a huge impact on your bass performance. This tutorial will show you specific strategies for placing your speakers to get a balanced bass response.



arqen.com















Speaker Boundary Interference Response SBIR GIK Acoustics


SBIR is a term to describe how the proximity of a speaker to a hard boundary (wall/ceiling/floor) will change the response, especially in the low end




www.gikacoustics.com


----------



## Cacitems4sale

I have a 15 x 23 ft room that I’m trying to add acoustic panels to. As you can see in the pictures I have Installed three panels, two on the side walls next to the first row seats and one on the rear wall. I have one more that I need to hang up, but I am uncertain the best place it should go. Can someone provide a recommendation? Thanks


----------



## nathan_h

Tough call. How thick are they?

Without knowing your speakers, assuming the panels are fiberglass, etc, I’d say the best guess would be that in most situations you likely want at least two (possibly three) on each side wall and then two on the back wall.

If some are thicker than others I’d put the thickest on the back wall. 

Ideally they would all be six inches thick, four is okay, but anything is likely better than nothing.


----------



## Cacitems4sale

Speakers are Klipsch 5502 in Walls. Insulation is 4” rock wool for all panels. Where on the sidewall should I install the additional panel?


----------



## nathan_h

The mirror test is a good one. You sit in your main seat. Someone slides a mirror along the side wall. Make sure your panels are placed anywhere you see a speaker reflected in the mirror. Chance are good one panel will capture the speaker closest to the wall and a second panel will cover the reflection point for the center and the furthest away speaker.


----------



## Hawks07

Cacitems4sale said:


> Speakers are Klipsch 5502 in Walls. Insulation is 4” rock wool for all panels. Where on the sidewall should I install the additional panel?


I would try it on the back wall. I took the panels I had between my first two rows down and actually like the livelier sound from the surrounds especially since I really don’t use the second row.


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## nathan_h

I agree the back wall would also benefit from a second panel. If that means you need to buy two more panels for the room, please try to get six inch panels for the back wall. That will absorb sound more evenly instead of simply deadening the high frequencies.


----------



## Cacitems4sale

Thanks all I ended up hanging it on the side wall about 2 ft away from the other. I’ll likely build 2 more panels, one to match up on the opposite side wall and add one to the backwall.
Since I’m new to this I’m a bit concerned that I could over due the dampening. Is that true and should I stop where I’m at? My goal was to decrease the echo in the room.


----------



## BeeAVision

I'm in the same boat as well. I'm also planning on building several broadband absorber panels along with bass traps and perhaps even a couple of diffuser panels for my small theater room. Hopefully I don't end up over doing it.


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## nathan_h

Measure before and after, try about 15% absorption (six inches is ideal, minimum four inches) and 15% diffusion, as a starting point.


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## DarinS

BeeAVision said:


> I'm in the same boat as well. I'm also planning on building several broadband absorber panels along with bass traps and perhaps even a couple of diffuser panels for my small theater room. Hopefully I don't end up over doing it.


What program are you using for the arrangements? Would like to map my room out. 


Sent from my iPhone using Tapatalk


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## BeeAVision

DarinS said:


> What program are you using for the arrangements? Would like to map my room out.


I used 3D modeling & rendering software along with Adobe Photoshop to create those illustrations.


----------



## Pretorian

nathan_h said:


> Measure before and after, try about 15% absorption (six inches is ideal, minimum four inches) and 15% diffusion, as a starting point.


How can you best measure your room?
Can I use the mic and Audyssey that I got with my Denon X4500? Will that show me how much reverb my room has?


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## nathan_h

Pretorian said:


> How can you best measure your room?
> Can I use the mic and Audyssey that I got with my Denon X4500? Will that show me how much reverb my room has?


1. well, you can follow the 15%”rule“ and it will likely work out very well, and stop there. 

2. the next step up in the sophistication of treatment is then doing measurement, and for that you would want to use the free REW computer program. I don’t know if the mic that comes with the receiver can be used with REW. Most people buy a usb microphone called a umik1 or similar calibrated microphone.


----------



## Pretorian

nathan_h said:


> 1. well, you can follow the 15%”rule“ and it will likely work out very well, and stop there.
> 
> 2. the next step up in the sophistication of treatment is then doing measurement, and for that you would want to use the free REW computer program. I don’t know if the mic that comes with the receiver can be used with REW. Most people buy a usb microphone called a umik1 or similar calibrated microphone.


15% rule?


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## nathan_h

Pretorian said:


> 15% rule?


15% of the surface area of the listening room should be covered with acoustic absorption panels. This is a pretty safe target for good sound in most rooms.


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## BeeAVision

Nathan, thanks for those references. I'll make sure to apply those principles into my overall design.


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## Pretorian

nathan_h said:


> 15% of the surface area of the listening room should be covered with acoustic absorption panels. This is a pretty safe target for good sound in most rooms.


Thanks again. That was very good and I always see almost the same image with how to end those early reflections the bass traps in the corner and thicker panels behind the listening position. 
It is what I got when discussing my room with GIK. 
It would be fun to measure and see the results in numbers before and after I treat my room. 
But maybe I just ”go with it” and hope that I will hear a difference.


----------



## EdgarQ

Hello everyone. I'm upgrading an art deco mahogany home theater in the house I just bought, and am stuck on acoustics.

So far, I replaced the 2008 HD projector with a JVC DLA NX5, and the 100" 16:9 screen with a 127" 2.35:1 screen (both installed by local vendor). I replaced all the A/V equipment with my own recent Denon AVR and other equipment, but kept the older Paradigm Model 9 v6 speakers which beat my own newer smaller lower sensitivity apartment speakers. I also wrapped some ultralight foam boards in Joann Royalty Black velvet to limit light reflections on the white plaster ceiling, the speakers, and the mahogany stage (DIY). I bought a row of 4 black leather home theater reclining seats (Octane Dream, the tables are missing in action - long story). I got this far by just lurking AVSForum. I was originally going to just do one reveal standalone post, and I still might when this is "over," but am getting a little worn out and just need to ask for help on the subject of sound.

I would love your advice on acoustic treatment. The room is a long narrow space (30'Lx13'Wx7.5'H), where the front is a home theater space, the middle is a bar, and the back is a fireplace and library, but all still one continuous space. For the home theater end of the space, the whole front of the room is mostly the screen, and then the front speakers take up what little space is left, standing in front of existing curtains. There's no room for treatments on the front wall or corners as far as I can tell, other than maybe resting a couple on the stage. The back wall in the library area has a fireplace, and movie posters on it now, that I'd prefer not to move, since I think of that area as a kind of lobby. Physics of course may disagree with my assigned designations. Less of a preference and more of a balance of factors is the ceiling. I don't know if it works to acoustic panel it, since it's plaster. My ultralight velvet panels were a risk, but I doubt anything heavier will be a good idea.

What's left available for treatment panels is the side walls. While there's some echo and reverb doing the clap test, the carpet and black shag rug, as well as the seats, may be doing some of the work already. But since there is still some echo and reverb, I'm thinking of paneling those walls somewhat. 

If I should rethink how I've got things set up so far, I'm open to hearing that. I figure there's no one solution, everyone is sharing what works for them, and what works is itself a balance between light, sound, aesthetics, time, space, cost, mental energy, DIY skill, and WAF. WAF should really be at the front of that list. Also, my get up and go got up and left, so probably not doing any more DIY. Also I have very little DIY talent and high aesthetic fussiness, which makes me my own worst enemy when looking at a half black, half white ceiling. At least it's not white on the left side (classic Trekkers, you know what I'm sayin').

Where was I? Oh yes, acoustic panels. I'm leaning toward 48x24x4 bass trap panels on the side walls in the front corners, which are where my first reflection points are, and then 4 more 36x24x4 acoustic panels for the side walls where the second reflection points are for all the four seats. I was planning to just buy all of them, but then started reading about diffusers, noticed that there's not much selection in diffusers from GIK or ATS, and fell asleep with my phone on my chest. I woke up without a magical solution, and decided to just ask for directions already. 

Let me know what you think!


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## nathan_h

Nice space.

Ideally one would measure the room with a calibrated microphone and know something about the type and location and orientation of the front speakers.

But a wild ass guess would be to use a few (ideally) six inch fiberglass panels, probably two 2’x4’ panels on each side wall between seats and screen wall, effectively damping first reflections.

Places like GIK have pretty patterns that might not mess with the decor too much?

Its possible that behind the screen could benefit from attention.


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## filmgeek47

Hey guys,

Hoping the acoustic masters that be can give me some advice. Here's my room currently:









It's about 12x15x8ft that's a dedicated theater (not really a 2 channel music guy). I've got a thin carpet over wood floors, but a huge chunk of the room is just a massive lounging sofa (fabric, not leather).

I've got an 7.2.4 setup, but for simplicity's sake I'm focusing on the 7 ear level speakers for treatment.

I did some basic research at the time that I made my treatments, but I was mainly focused on taming some nasty slap echo at the time, rather than overall acoustic performance.

Now I'd like to make sure I've got my treatment in the best possible positions, and that I don't have too little or too much.

Current treatment is 5 2'x4'x2" Owens Corning Fiberglass panels, hung on the sides and back wall. I also have two corner bass traps, about 5ft high, 12" at their deepest point.

My main issue right now, is I feel like the surrounds are a bit muddled compared to the clear imaging I get in front. To combat that, my plan was to build four "mini" panels, 1'x4'x2" to squeeze in around the listening position at the back of the room. I may also build a bigger panel to go on the ceiling and absorb the early ceiling reflections from the center channel.

Based on the "15% rule," I've got 792 sq ft of surface area (including floor and ceiling). If I assume the 1/2" carpet isn't much good at absorption, my panels add up to roughly 55 sq ft of absorption, so in theory I could use some more?

Here's what I had in mind:










Question one is, do you think that's a good plan?

Question 2... I'm planning on replacing my current media center at the front of the room with a DIY alternative. My wife would be thrilled if I could stick the center channel inside the top of the cabinet. Given free rein to design a cabinet that's most accommodating to the speaker, what are the odds that I can make it work without significantly compromising the sound?

Some options I was considering was making a fairly oversized space for the speaker, letting it hang out of the cabinet by a half inch or so, and lining the inside of the cabinet with spare 2" acoustic foam. I'd also probably leave a gap between the open back of the cabinet and the front wall to allow sound to escape.

Thoughts?


----------



## EdgarQ

nathan_h said:


> Nice space.
> 
> Ideally one would measure the room with a calibrated microphone and know something about the type and location and orientation of the front speakers.
> 
> But a wild ass guess would be to use a few (ideally) six inch fiberglass panels, probably two 2’x4’ panels on each side wall between seats and screen wall, effectively damping first reflections.
> 
> Places like GIK have pretty patterns that might not mess with the decor too much?
> 
> Its possible that behind the screen could benefit from attention.


Thanks Nathan! I do have the mic that came with my Denon AVRX4500 for setting the levels, but I don’t have anything in hand to measure the sound. The front channels are 2.5-way 4 driver bass reflex midsize floor standing speakers, with 96dB sensitivity, and connected with their bi-wiring posts. They are standing right in the corners slightly angled into the room. I have them on short stands as well, to have them roughly pointed at the loveseat center of the one row of seats.

Your WAG works for me, having 4-6 panels along the walls for the early reflections is pretty much where I’m headed. I’ll keep it all GOM pitch black if I can help it, I do want to limit as much light reflection as possible bouncing back to the screen. I’ve got 80% of that under control, and it can mitigate the side walls a bit with black fabric, that gives me another 5%!


----------



## fattire

EdgarQ said:


> Thanks Nathan! I do have the mic that came with my Denon AVRX4500 for setting the levels, but I don’t have anything in hand to measure the sound. The front channels are 2.5-way 4 driver bass reflex midsize floor standing speakers, with 96dB sensitivity, and connected with their bi-wiring posts. They are standing right in the corners very slightly angled into the room. I have them on short stands as well, to have them directly pointed at the loveseat center of the one row of seats.
> 
> Your WAG works for me, having 4-6 panels along the walls for the early reflections is pretty much where I’m headed. I’ll keep it all GOM pitch black if I can help it, I do want to limit as much light reflection as possible bouncing back to the screen. I’ve got 80% of that under control, and it can mitigate the side walls a bit with black fabric, that gives me another 5%!


Be aware that you’re going to be in a wait if ordering from GIK. I placed an order last Friday for 4 x (2x4x6) and 4 x (2x12x6) panels. Estimated ship date is June 23rd . A friend ordered bass traps in early April and his ship date is last week of May. It’s all due to supply chain issues that many companies are experiencing right now.


Sent from my iPhone using Tapatalk


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## filmgeek47

Guys, is there anything approaching a consensus on whether you should diffuse the back wall and place spaced out absorption on the sides, vs the reverse? Trying to figure out what makes the most sense in my room, and I'm really not sure which way to go.


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## EdgarQ

fattire said:


> Be aware that you’re going to be in a wait if ordering from GIK. I placed an order last Friday for 4 x (2x4x6) and 4 x (2x12x6) panels. Estimated ship date is June 23rd . A friend ordered bass traps in early April and his ship date is last week of May. It’s all due to supply chain issues that many companies are experiencing right now.
> 
> 
> Sent from my iPhone using Tapatalk


Omigosh! I'm so glad you mentioned that! Does anyone know if ATS Acoustics backed up as well? I'll ask them directly too.


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## nathan_h

filmgeek47 said:


> Guys, is there anything approaching a consensus on whether you should diffuse the back wall and place spaced out absorption on the sides, vs the reverse? Trying to figure out what makes the most sense in my room, and I'm really not sure which way to go.


Grimani just did a series of seminars on the audiohilics youtube channel and discussed this. After designing the acoustics in more than a thousand rooms he has concluded that thick absorption behind the listener on the back wall is far superior to diffusion in domestic sized rooms.

He likes diffusion on the back wall on the sides, ie, not directly behind the listeners.


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## filmgeek47

nathan_h said:


> Grimani just did a series of seminars on the audiohilics youtube channel and discussed this. After designing the acoustics in more than a thousand rooms he has concluded that thick absorption behind the listener on the back wall is far superior to diffusion in domestic sized rooms.
> 
> He likes diffusion on the back wall on the sides, ie, not directly behind the listeners.


Thanks! I know people usually prefer 4”+ for absorbers. I’m stuck with 2” for asthetic reasons (I also have bass traps). is that still better than nothing?


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## nathan_h

filmgeek47 said:


> Thanks! I know people usually prefer 4”+ for absorbers. I’m stuck with 2” for asthetic reasons (I also have bass traps). is that still better than nothing?


yes probably still good to use on the back wall.

too many 2” traps become problematic before too many six inch traps since six inch ones dial down ”all” frequencies instead of just damping the top treble frequencies like 2“ ones.... which, when overdone, can take high end treble energy out of a room (starts to act like a tone control).


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## filmgeek47

nathan_h said:


> too many 2” traps become problematic before too many six inch traps since six inch ones dial down ”all” frequencies instead of just damping the top treble frequencies like 2“ ones.... which, when overdone, can take high end treble energy out of a room (starts to act like a tone control).


Gotcha. I have been able to measure my room with REW, and my frequency response seems pretty even so I don’t think I’ve overdone the absorption yet.

What do you think of this approach:


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## nathan_h

I would use a mirror on the side walls to figure out the first reflection points and make sure they have treatment there. From the diagram it seems like some might be bare.


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## filmgeek47

nathan_h said:


> I would use a mirror on the side walls to figure out the first reflection points and make sure they have treatment there. From the diagram it seems like some might be bare.


They are. Unfortunately it’s the ones that intersect with the door on the left, and I left the right wall bare for symmetry purposes.


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## nathan_h

filmgeek47 said:


> They are. Unfortunately it’s the ones that intersect with the door on the left, and I left the right wall bare for symmetry purposes.


I haven't seen photos of your room, but in my room, a normal 2' wide 4' tall panel fit on my door very nicely...


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## filmgeek47

nathan_h said:


> I haven't seen photos of your room, but in my room, a normal 2' wide 4' tall panel fit on my door very nicely...


Wife and I have been refinishing the house, and we put in a beautiful stained wood door before I knew what I was doing with acoustics. She's been a pretty good sport about the theater room stuff, but putting a panel on the door is a no go. 

I think I can get away with putting one panel on the ceiling to cover the first reflection from the center channel though.

Given my limitations, should I just not worry about diffusion, and put 2" panels in all the locations I marked? I'm also getting some advice in another thread, and I'm getting some people advocating exclusively using absorption because of the size of the room (and because it's pretty much exclusively HT use). Others are suggesting I put diffusion in the areas I've marked.

I'm building all the panels myself, so I'd like to get it right this time!


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## nathan_h

There is relatively little evidence that diffusion in a small room like this is worthwhile. Diffusion works best when someone deep and when you have more space between it and the listener.

That said, it is possible to put too much absorption in the room, especially if all the panels are two inches thick since they absorb higher end frequencies well, but leave midrange / upper bass untouched, so they can act like a tone control or kill the air without evenly attenuating lower frequencies.

So I agree with the general advice you are getting elsewhere, though anywhere you can do a 4 or six inch panel instead of 2" would be a good substitution.

The other way to avoid killing the treble too much are with what are called "scatter plates". You can see these on the GIK web site. It is a normal absorption panel, like we are talking about, with a design on the front made of wood. That wood reflects some high end energy back into the room without absorbing it all. This is something to keep in mind if you end up with a little too little "air" in the sound (too little treble).

Two other ideas to note:

1. While I haven't encountered it/tried it very much enough to have first hand experience, Anthony Grimani has started doing non-symmetrical room treatments -- like an absorber on one wall and a scattering treatment on the other wall, opposite it -- and he claims it works very well. So you might want to try putting an absorption panel across from the door, even if you cannot treat the door, at least as an experiment, at some point, and see what you think. 

2. Some speakers handle a reflective room better than others. If your speakers have wide, even, consistent dispersion (sometimes called "good directivity" which is confusing because they are LESS directional and more diffuse) then you can get away with less absorption. I don't know what your speakers are. So I am erring on the side of assuming they are "average" and not (for example) something like Revel which is known for having wide even dispersion.


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## EdgarQ

EdgarQ said:


> Omigosh! I'm so glad you mentioned that! Does anyone know if ATS Acoustics backed up as well? I'll ask them directly too.


ATS sales says: “Due to a worldwide insulation shortage, I would say 2-4 weeks would be a safe lead time to go by.”


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## filmgeek47

nathan_h said:


> There is relatively little evidence that diffusion in a small room like this is worthwhile. Diffusion works best when someone deep and when you have more space between it and the listener.
> 
> That said, it is possible to put too much absorption in the room, especially if all the panels are two inches thick since they absorb higher end frequencies well, but leave midrange / upper bass untouched, so they can act like a tone control or kill the air without evenly attenuating lower frequencies.
> 
> So I agree with the general advice you are getting elsewhere, though anywhere you can do a 4 or six inch panel instead of 2" would be a good substitution.
> 
> The other way to avoid killing the treble too much are with what are called "scatter plates". You can see these on the GIK web site. It is a normal absorption panel, like we are talking about, with a design on the front made of wood. That wood reflects some high end energy back into the room without absorbing it all. This is something to keep in mind if you end up with a little too little "air" in the sound (too little treble).
> 
> Two other ideas to note:
> 
> 1. While I haven't encountered it/tried it very much enough to have first hand experience, Anthony Grimani has started doing non-symmetrical room treatments -- like an absorber on one wall and a scattering treatment on the other wall, opposite it -- and he claims it works very well. So you might want to try putting an absorption panel across from the door, even if you cannot treat the door, at least as an experiment, at some point, and see what you think.
> 
> 2. Some speakers handle a reflective room better than others. If your speakers have wide, even, consistent dispersion (sometimes called "good directivity" which is confusing because they are LESS directional and more diffuse) then you can get away with less absorption. I don't know what your speakers are. So I am erring on the side of assuming they are "average" and not (for example) something like Revel which is known for having wide even dispersion.


Good to know, thanks. My speakers are Martin Logan Motion 40s, motion 30, and the smaller motion 4i and motion fx for the surrounds. They claim it’s 80 degree dispersion, so I’m not sure if that qualifies as wide/even or not.

in terms of throwing off the frequency response with inconsistent absorption, is that not something that my room correction (Audyssey XT32) can somewhat compensate for?

I have REW measurements of the space with my current panel layout. I assume I should be watching out for the 80-500hz range being louder than the 500-20000 range?

I assume I could imitate a scatter plate by throwing some thin properly spaced strips of plywood inside the panels in front of the fiberglass, right?


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## nathan_h

filmgeek47 said:


> Good to know, thanks. My speakers are Martin Logan Motion 40s, motion 30, and the smaller motion 4i and motion fx for the surrounds. They claim it’s 80 degree dispersion, so I’m not sure if that qualifies as wide/even or not.


Its not just dispersion but well behaved dispersion -- ie, the same kind of frequency response off axis as one axis. 

I can't find CEA2034 measurements of those ML speakers. So to be safe, treating sidewall reflections is what I would do (as you have done).



> in terms of throwing off the frequency response with inconsistent absorption, is that not something that my room correction (Audyssey XT32) can somewhat compensate for?


Audyssey is quite good. It isn't as good as simply not messing up the frequency response however, so rather than rely on it to counteract too much absorption, if you conclude you have too much absorption, reducing the amount of absorption would be a better approach.



> I have REW measurements of the space with my current panel layout. I assume I should be watching out for the 80-500hz range being louder than the 500-20000 range?


That is worth paying attention to, as well as decay time, and how it sounds to your ears.



> I assume I could imitate a scatter plate by throwing some thin properly spaced strips of plywood inside the panels in front of the fiberglass, right?


I think the answer is "yes" to the extent that it is worth trying but I am still learning about this approach.


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## filmgeek47

nathan_h said:


> Its not just dispersion but well behaved dispersion -- ie, the same kind of frequency response off axis as one axis.
> 
> I can't find CEA2034 measurements of those ML speakers. So to be safe, treating sidewall reflections is what I would do (as you have done).
> 
> 
> 
> Audyssey is quite good. It isn't as good as simply not messing up the frequency response however, so rather than rely on it to counteract too much absorption, if you conclude you have too much absorption, reducing the amount of absorption would be a better approach.
> 
> 
> 
> That is worth paying attention to, as well as decay time, and how it sounds to your ears.
> 
> 
> 
> I think the answer is "yes" to the extent that it is worth trying but I am still learning about this approach.


Nathan, thank you so much for your help! I've swayed the wife into letting me make the back wall absorbers 4" instead of 2". I was looking at my RT30 graphs, and there's a decent bump from about 200-400hz, so I figure that should at least shrink the upper part of that bump. Looking at REW, audyssey seems to be doing a decent job of leveling out the FR, so I'm not too worried about adding in a bit more absorption (the goal being to diminish the reflections from the surrounds, which I think is muddying my surround imaging and clarity).

Long term, I'm planning on building a long skinny table to sit behind the sofa. I'm thinking I may fill the space underneath it with one big squarish bass trap running along most of the back floor. If I make it something like 18"x18"x8' I figure that should be pretty helpful in taming the lows, right?


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## nathan_h

Position of such a substantial trap will impact how well it does for you, but it is worth trying.


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## harrisu

Hi guys. I recently replaced the stands my subs were standing on with Shelves. This gave me a lot of extra space (see pics below). I have room modes b/w 70-300Hz. I have moved speakers back and forth and also MLP but didn't get much luck. I have heard that pink stuff bags from Home Depot (R-30 I think) can help???? I understand that fixing 70-100Hz requires a lot more depth but I'm hoping to fix b/w 100-300Hz. Posting L/C/R full response and also the space available.


























Space available. Behind speakers b/w subs is ~6 feet length, 20" depth, 40" height.










Close up of the space available. I stappled 1" Linaccoustic before and all the while holes you see is the staples pins that left the marks


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## nathan_h

Those dips between 100 and 200 look big but are very narrow. I’d guess that you can’t hear them.

The issues below 100 he can largely be solved by running two (if you only have one row of seats) or four subs (multiple rows) correctly and crossing over the mains at 80 or 100 hz.


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## harrisu

nathan_h said:


> Those dips between 100 and 200 look big but are very narrow. I’d guess that you can’t hear them.
> 
> The issues below 100 he can largely be solved by running two (if you only have one row of seats) or four subs (multiple rows) correctly and crossing over the mains at 80 or 100 hz.


I have 4 subs  (described under my signature). I have no problem with subs response. I get pretty flat response across my 3 seats and if there is any deviation, I let MSO do the work for me. Here is my C+S response after running 9 points Dirac spread across 3 seats. I did 9 points because once I'm satisfied, I'll go with all 17 points.










But look how Left ends up coming










Dirac cuts the peaks but ends up with dips. Is that not audible? Even it its not, that's a lot of mid bass missing from Left. Right is pretty much the same. My L/C/R are JBL 4722N which contains 2 15" drivers each and are very capable to produce tons of midbass. Plus I use Dirac which gives me flexibility to define custom curve. So trying different curve with different boosts around 100-300 can be very effective but not when the speaker response has issues in that region like my Left/Right do. Center is doing well. 

Front subs are on shelf and are right behind the L/R spekers. I wonder if they are some how causing it. It might sound crazy but when I was finding the best locations for subs, I moved the all around and took readings and once I found the best spots, I moved my L/C/R speakers back in and guess what??? they changed subs output below 40Hz. I was shocked so I moved speakers back out just to make sure I'm not going crazy and yep, FR did go back to normal. So I had to place speakers and then move subs around again to get best FR. Clearly these boxes in place are changing FR in 70-300Hz range. So now I'm wondering if these subs right behind and above L/R are causing it. But subs do sound great there .


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## nathan_h

This is challenging and seeing graphs after running dirac makes understanding the room acoustic hard. Plus I like the response before Dirac. Measures better from what your graphs show. Fewer large wide dips. A narrow deep dip is much less audible than a wide one even if the wide one is less deep. Turn on “perceptual smoothing” in REW (it’s like choosing 1/12th octave smoothing etc, but it changes how much smoothing it does based on human hearing acuity) and those deep narrow dips may disappear......


Other thoughts:

1. Could be sbir? If you move the left speaker closer to the left wall, does that dip happen higher up in the frequency range?

I would suspect if it is sbir that the left and right speaker would have a similar problem because they are both the same distance from the front wall, side wall, floor and ceiling. But if the room and construction are not symmetrical (like one side has a door, or one side it an external wall, etc) that might explain the difference.


2. Long shot: I would experiment with changing the crossover a bit. Sometimes that impacts an octave above and below in a good way.

I would experiment with changing the single distance setting for the sub. (I know you have multiple but they are correctly running in mono so I call them one sub.). Sometimes that can help with the frequency response above and below the crossover point. 

*That said it’s not obvious this is a sub integration issue since you have the dips in each channel when running each channel without a sub too. *


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## Sands_at_Pier147

nathan_h said:


> Other thoughts:
> 
> 1. Could be sbir? If you move the left speaker closer to the left wall, does that dip happen higher up in the frequency range?


It does seem like SBIR to me. Is there any acoustical treatment on the wall for reflections from the speaker to the measurement point? Maybe absorption would reduce interference / comb filtering at the listening position. Or maybe another inch of linacoustic behind the speakers for the same reason? The L/R may be corner loading and creating interference you don't see with the Center?


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## DarinS

Quick question concerning SBIR. My theater walls go up in the next week or so. (Been waiting a month on getting enough mineral wool to fill the walls but that is now ready to go in before my double layer of 5/8" drywall/green glue/hat channel). Anyway, I will not have a baffle wall but will have a screen wall that is fully AT with at least one sub (maybe 2...depends on REW) and 3 JBL 4722n's behind it. From what I've read, everything behind the screen wall should be sound absorption since no baffle wall. If correct, what is the best product to put back there and how thick? I have the list from @BIGmouthinDC which shows numerous absorption coefficients for different materials but that is somewhat overwhelming. So, simple question as above. What product and how thick? Thanks!


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## fattire

DarinS said:


> Quick question concerning SBIR. My theater walls go up in the next week or so. (Been waiting a month on getting enough mineral wool to fill the walls but that is now ready to go in before my double layer of 5/8" drywall/green glue/hat channel). Anyway, I will not have a baffle wall but will have a screen wall that is fully AT with at least one sub (maybe 2...depends on REW) and 3 JBL 4722n's behind it. From what I've read, everything behind the screen wall should be sound absorption since no baffle wall. If correct, what is the best product to put back there and how thick? I have the list from @BIGmouthinDC which shows numerous absorption coefficients for different materials but that is somewhat overwhelming. So, simple question as above. What product and how thick? Thanks!


SBIR is a function of distance from the driver to the boundary. You can do math but here’s a quick reference chart: Moulton Laboratories :: Taming the Big Wave

A 4722n shows to be 17.75 in deep. If it were touching the wall that would be just under 200 Hz. That’s pretty easy to tame with 4” OC 703 or similar material. You’d need room for that insulation so add 4” (keep assuming everything is just touching to make it simple. Distance is now 21.75 in pushing closer to 150 Hz and you probably need 6” to be safe. So 2” more away from the wall … frequency goes lower again to the 140-ish range. But … you’re still good with 6” of material . 

That’s just an example though. As you can see, further from the wall the front of the driver is, the frequency gets lower. It doesn’t take much distance to put the frequency into a range that’s easier to treat with a crossover to (hopefully) well integrated and multiple subs. Be aware that subs can suffer from SBIR too! However, with an AT screen you can play games like turning the subs sideways (who cares if you can see the amp) to get the driver closer to the wall and eliminate the issue for them (closer = higher frequency and easy to get out of the sub’s responsibilities!). 

Figure out how far from the wall the front of the speaker will be. Use that to get an idea of the possible issue frequency (just an idea; there’s always wiggle room depending on construction type and such). You’ll probably just end up with 6” of 703 or Rockwool or whatever regardless, and then manage anything below with tuning and sub integration. If you have the space, you could always double up on the absorption, but again, wavelengths get big FAST so it probably won’t get you much for the expense vs a good crossover point. 

I learned this ^^ from @sdurani ; so I hope I got it all correct!


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## nathan_h

Sands_at_Pier147 said:


> It does seem like SBIR to me. Is there any acoustical treatment on the wall for reflections from the speaker to the measurement point? Maybe absorption would reduce interference / comb filtering at the listening position. Or maybe another inch of linacoustic behind the speakers for the same reason? The L/R may be corner loading and creating interference you don't see with the Center?


@fattire post above this covers it pretty well. Put the six inch thick panel behind the speaker and the speaker as close to the wall as possible.


----------



## SimpleTheater

Here's a doozy.


----------



## DarinS

nathan_h said:


> @fattire post above this covers it pretty well. Put the six inch thick panel behind the speaker and the speaker as close to the wall as possible.


Panel just behind the speakers or the entire wall? If just speaker, that includes sub too,right?


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## fattire

DarinS said:


> Panel just behind the speakers or the entire wall? If just speaker, that includes sub too,right?
> 
> 
> Sent from my iPhone using Tapatalk


For SBIR you just need to address the area directly behind each speaker (sub too). However, it would be best to treat the entire wall behind the screen if possible. 

Why?

To kill reflections from your rear surrounds and other non-front speakers. It’s the same reason most folks will recommend at least some absorption on the back wall to kill reflections from the non-surround speakers. 


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## DarinS

fattire said:


> For SBIR you just need to address the area directly behind each speaker (sub too). However, it would be best to treat the entire wall behind the screen if possible.
> 
> Why?
> 
> To kill reflections from your rear surrounds and other non-front speakers. It’s the same reason most folks will recommend at least some absorption on the back wall to kill reflections from the non-surround speakers.
> 
> 
> Sent from my iPhone using Tapatalk


That’s what I thought. I heard for screen wall to make it full AT and wall behind in full absorption. 


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## DarinS

I have also heard general recommendation is have about 15% of the room treated with absorption. My space is about 25'x15'x9'. By my calculations, treating my front wall complete with absorption will hit about 9.2% of my total wall space. My question about that calculation is this: I included the floor space which will be covered in carpet. I am assuming that counts in the total surface area of the room but not as absorption since it is just your basic carpet with pad. Is this correct? If so, it sounds like I would potentially need a little more absorption at the back of the room and then maybe the first reflections up front. That sound about right?

This equates to an additional 85 ft^2 of absorption panels to make or buy.


----------



## fattire

DarinS said:


> I have also heard general recommendation is have about 15% of the room treated with absorption. My space is about 25'x15'x9'. By my calculations, treating my front wall complete with absorption will hit about 9.2% of my total wall space. My question about that calculation is this: I included the floor space which will be covered in carpet. I am assuming that counts in the total surface area of the room but not as absorption since it is just your basic carpet with pad. Is this correct? If so, it sounds like I would potentially need a little more absorption at the back of the room and then maybe the first reflections up front. That sound about right?
> 
> This equates to an additional 85 ft^2 of absorption panels to make or buy.


That is correct. The floor counts as area, the carpet doesn't count as absorption. But ... furniture can if it's big fluffy stuff. We have a huge, overstuffed, upholstered couch (cloth, not leather) with 2 storage ottomans. It does a great job sucking up a lot of the reverb in our room. I'm just treating for SBIR and the contra-lateral first reflection points (i.e. using the mirror trick, when the mirror is on the right, you see the left speaker and vice-a-versa).

I tested using some left-over pink fluffy but am (im)patiently waiting for panels from GIK at the end of next month.


----------



## sdurani

DarinS said:


> My question about that calculation is this:


Instead of calculating surface area percentages, I would figure out which reflections I prefer and which I don't. To keep the soundstage clean and articulate, I wouldn't want any reflections muddying the sound coming from my L/C/R speakers. Same with reflections from the Centre speaker bouncing off the middle of the back wall. So those seem like natural spots for absorption. With side walls, I prefer ipsi-lateral (same side) reflections that widen the soundstage but not contra-lateral (opposite side) reflections that can mess with directionality. It never occurred to me to calculate what percentage of the surface area of the room those absorbers take up.


----------



## fattire

sdurani said:


> ipsi-lateral (same side) reflections that widen the soundstage but not contra-lateral (opposite side) reflections that can mess with directionality.


ipsi-lateral, not iso-lateral Fattire 🤦‍♂️. Thanks Sanjay 😉


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## squared80

DarinS said:


> I have also heard general recommendation is have about 15% of the room treated with absorption. My space is about 25'x15'x9'. By my calculations, treating my front wall complete with absorption will hit about 9.2% of my total wall space. My question about that calculation is this: I included the floor space which will be covered in carpet. I am assuming that counts in the total surface area of the room but not as absorption since it is just your basic carpet with pad. Is this correct? If so, it sounds like I would potentially need a little more absorption at the back of the room and then maybe the first reflections up front. That sound about right?
> 
> This equates to an additional 85 ft^2 of absorption panels to make or buy.


Carpet/padding would only matter if your padding was 6" think or more. Don't count it.


----------



## DarinS

fattire said:


> A 4722n shows to be 17.75 in deep. If it were touching the wall that would be just under 200 Hz. That’s pretty easy to tame with 4” OC 703 or similar material. You’d need room for that insulation so add 4” (keep assuming everything is just touching to make it simple. Distance is now 21.75 in pushing closer to 150 Hz and you probably need 6” to be safe. So 2” more away from the wall … frequency goes lower again to the 140-ish range. But … you’re still good with 6” of material


You mentioned 6" of insulation on front wall, but when I search about the thickest I can find is 4 inch Rockwool or 703 type of materials. Is there a 6in thick product generally recommended or would a 4" mineral wool be sufficient? Secondly, how do you even hang that stuff on drywall?


----------



## fattire

DarinS said:


> You mentioned 6" of insulation on front wall, but when I search about the thickest I can find is 4 inch Rockwool or 703 type of materials. Is there a 6in thick product generally recommended or would a 4" mineral wool be sufficient? Secondly, how do you even hang that stuff on drywall?


Double up the 3" or use 4" with a 2" air-gap behind it. The air-gap method works _almost_ as well as 6" of actual material so it could be a less expensive way to achieve the desired outcome.

Mounting depends on the material. OC fiberboard is pretty easy. You can just screw it in (just don't go crazy and drive the screw all the way through the material 😉). More bat-based stuff like Rockwool is more challenging. It would need some sort of simple framing to provide some support. You'd need something like this anyway with an air gap behind 4" material so again ... should be pretty trivial depending on the route you choose to take.

If it were me, I'd probably go the double-layer fiberboard route. It's easier to cut and mount and I can be a bit lazy like that. The disadvantage, of course, is the higher cost. I'm not sure if 3" material with a 3" air-gap would accomplish what you need. I just don't have enough experience in that area. I know smaller air-gaps work great, just not sure when the ratio of material to air-gap is as high as 1:1. Perhaps @nathan_h or @sdurani can chime in on that one.

EDIT: Found a good discussion here: Appropriate size of Air Gap for Acoustic Traps


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## squared80

DarinS said:


> You mentioned 6" of insulation on front wall, but when I search about the thickest I can find is 4 inch Rockwool or 703 type of materials. Is there a 6in thick product generally recommended or would a 4" mineral wool be sufficient? Secondly, how do you even hang that stuff on drywall?


Just stack it if you're going 6".


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## BeeAVision

So I made some further changes to my acoustical treatments in my small theater. After reviewing Anthony Grimani's videos and acquiring additional advice from fellow board members I came up with this new revision. I went with cylindrical over quadratic diffusers since the seating will be less than 4' away from the side walls. I haven't yet addressed the front wall nor the ceiling with the exception of the bass traps in the corners. The door at the entrance into the room opens in with very little room for adding treatments there. So the door and adjacent wall will have to remain untreated for the time being. The panels with no insulation in them are simply for cosmetic looks. However, these panels may provide for future treatment if it's needed later. All panels and bass traps will be fully removable. Panels will use Z Clips to mount to the walls. This will especially be helpful when needing to gain access to both the HVAC closet and attic. Feel free to point out any mistakes I may have overlooked. I'm expecting to make more changes as I continue to learn from this. With that said, I'm certainly not looking to obtain total perfection but a relatively nice balance between basic treatment and artistic design on a tight budget.


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## 04rex

Hey guys,

I recently contacted GIK about what kind of Acoustic panels I should do, and where to put them and all of that because I have absolutely ZERO idea about any of this stuff. Just wondering if their recommendations are usually solid? I sent them pics of my room as well as the dimensions and they recommended what and where I should put them. Am I good to take their advice and go for it?

Thanks for any help.


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## tidwelr1

04rex said:


> Hey guys,
> 
> I recently contacted GIK about what kind of Acoustic panels I should do, and where to put them and all of that because I have absolutely ZERO idea about any of this stuff. Just wondering if their recommendations are usually solid? I sent them pics of my room as well as the dimensions and they recommended what and where I should put them. Am I good to take their advice and go for it?
> 
> Thanks for any help.


Yes. They are very well respected. I just ordered some 4” and 2” acoustic art panels myself. 


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## 04rex

Thank you for that!


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## nathan_h

Yeah I didn’t believe some of their advice but eventually tried it. They were right.


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## Pretorian

04rex said:


> Hey guys,
> 
> I recently contacted GIK about what kind of Acoustic panels I should do, and where to put them and all of that because I have absolutely ZERO idea about any of this stuff. Just wondering if their recommendations are usually solid? I sent them pics of my room as well as the dimensions and they recommended what and where I should put them. Am I good to take their advice and go for it?
> 
> Thanks for any help.


I have been in contact with them for several months with the same question(s). I am about ot order my first kit probably today. I got a good impression from the person I talked to. Dont know how long delivery is but I guess a few weeks.


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## tcoble33

Pretorian said:


> I have been in contact with them for several months with the same question(s). I am about ot order my first kit probably today. I got a good impression from the person I talked to. Dont know how long delivery is but I guess a few weeks.


I ordered a set of bass traps from GIK a while back. At that time, they were quoting a seven-week lead time. That has since stretched by an additional two weeks due to issues with raw material availability. Time will tell whether that gets bumped out any further. Still, in the overall scope of things it's worth the wait - and the GIK team has been great to work with in regard to maintaining good communication/updates.


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## fattire

Pretorian said:


> I have been in contact with them for several months with the same question(s). I am about ot order my first kit probably today. I got a good impression from the person I talked to. Dont know how long delivery is but I guess a few weeks.


Could be a few months. I ordered 8 x 244s on 18 April. Estimated ship date provided to me on 19 April was 23 June. No updates from GIK since then. Just be prepared to wait and patient with the shipping/delivery issues everyone is dealing with.


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## tidwelr1

Pretorian said:


> I have been in contact with them for several months with the same question(s). I am about ot order my first kit probably today. I got a good impression from the person I talked to. Dont know how long delivery is but I guess a few weeks.


Try two months! That’s the lag they have right now. John that helped me said their biz has exploded during the pandemic. 


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## tidwelr1

I’m looking at possibly getting window curtains for my room that currently has blinds. I would guess the blinds scatter the sound some though. Anyways, any recommendations for curtains that would be good for theatre purposes? 


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## nathan_h

The impact will be minimal. Thicker and more pleats the better.


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## tidwelr1

nathan_h said:


> The impact will be minimal. Thicker and more pleats the better.


Ok. Thanks. 


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## ajax-jp

fattire said:


> Could be a few months. I ordered 8 x 244s on 18 April. Estimated ship date provided to me on 19 April was 23 June. No updates from GIK since then. Just be prepared to wait and patient with the shipping/delivery issues everyone is dealing with.


Same. I ordered 6x244's and 8xTri Traps on April 20th. Their estimated ship date was June 24th.
I thought maybe it was due to custom sizes on 4 of my Tri Traps, but apparently not.


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## Pretorian

tidwelr1 said:


> Try two months! That’s the lag they have right now. John that helped me said their biz has exploded during the pandemic.
> 
> 
> Sent from my iPhone using Tapatalk


Order is done. 10-20 work days. I ordered from the EU since I live in Sweden.


----------



## AndreNewman

tidwelr1 said:


> I’m looking at possibly getting window curtains for my room that currently has blinds. I would guess the blinds scatter the sound some though. Anyways, any recommendations for curtains that would be good for theatre purposes?
> 
> 
> Sent from my iPhone using Tapatalk


We have floor to ceiling thick black velvet curtains on all walls, a little over double width so >2:1 pleat, well except the screen of course. I'm amazed how much difference it does actually make, we have them for light control but they have a significant acoustic benefit too.

These were relatively cheap Amazon mixed fabric velvet, I'd send you a link but I bought out all their stock!

Here's a REW trace from my right channel, red is curtains closed, green is open. I expect the difference would be even more if the curtains were removed from the room completely.

I expected the effect from 600Hz up but the benefits at 60 to 100Hz were completely unexpected.










And impulse


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## rbolen

I have an acoustic treatment question, and I thought this was the most appropriate place to ask. 

I'm in the pre-planning stages of converting a finished room over my garage into a theater room. It is 23 x 11.5 x 6.25/9.25 (slanted side walls that follow roof lines). I have calculated out the surface area of my room, including floor (carpet), and it is 1072 sqft. I understand between 15-20% treatment is probably ideal. I plan to have a false wall with an AT screen, about 32in from the front wall, and plan to treat all surfaces behind the AT screen (probably 2in linacoustic + 3mm poly + 2in linacoustic). If I treat all this space, I have already treated 169 sqft, or, a little over 15% of my room. I fully planned on having 10 or 12 4ftx2ft panels at first reflection points on side walls, at the rear, and beside/near my surrounds. This would seem like a mathematical problem, and I will end up having my room over-treated. Does this suggest that I don't treat all the surface behind the AT screen?

Sorry if this is simple, I'm just having a hard time wrapping my head around it, as most recommendations I see suggest treating all area behind a false-wall/AT-screen. 

Thanks!


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## squared80

rbolen said:


> I have an acoustic treatment question, and I thought this was the most appropriate place to ask.
> 
> I'm in the pre-planning stages of converting a finished room over my garage into a theater room. It is 23 x 11.5 x 6.25/9.25 (slanted side walls that follow roof lines). I have calculated out the surface area of my room, including floor (carpet), and it is 1072 sqft. I understand between 15-20% treatment is probably ideal. I plan to have a false wall with an AT screen, about 32in from the front wall, and plan to treat all surfaces behind the AT screen (probably 2in linacoustic + 3mm poly + 2in linacoustic). If I treat all this space, I have already treated 169 sqft, or, a little over 15% of my room. I fully planned on having 10 or 12 4ftx2ft panels at first reflection points on side walls, at the rear, and beside/near my surrounds. This would seem like a mathematical problem, and I will end up having my room over-treated. Does this suggest that I don't treat all the surface behind the AT screen?
> 
> Sorry if this is simple, I'm just having a hard time wrapping my head around it, as most recommendations I see suggest treating all area behind a false-wall/AT-screen.
> 
> Thanks!


It's a guideline. Good idea to treat the front stage. Then treat first reflections off the ceiling and sides, then again at the rear. Sounds like you're on the right track.


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## rbolen

squared80 said:


> It's a guideline. Good idea to treat the front stage. Then treat first reflections off the ceiling and sides, then again at the rear. Sounds like you're on the right track.


Thanks. I think I was obsessing too much about the numbers (percent).


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## sdurani

rbolen said:


> I'm just having a hard time wrapping my head around it, as most recommendations I see suggest treating all area behind a false-wall/AT-screen.


The _'percentage of surface area'_ approach can break up reflections in an untreated room so that things don't sound so harsh. It is one approach to treating a room, but not the only approach. Another approach is to think about which reflections you want to keep and which ones you want to get rid of, based on direction.

Even in this day and age of surround sound, the front soundstage remains critical. That's where your attention will be focused, whether watching a movie or listening to music. As such, it's a good idea to absorb reflections bouncing off the front wall that would muddy the front soundstage. You want surround and height sounds to come from around/above you, not reflected off the front wall, coming from the same direction as the front soundstage. Same reason to cover the middle half of the back wall (directly opposite the Centre speaker).

Lateral (sidewall) reflections can aid in spaciousness. Absorbing them comes down to personal preference. Ipsi-lateral (same side) reflections tend to widen the soundstage, which is usually preferred by most listeners. The only absorption I would use on the side walls is at the contra-lateral (opposite side) reflections. I don't like sounds from the left speaker coming at me (however subtly) from the right side of the room. YMMV.

So rather than think in terms of a math problem, think about sculpting the sound in your room. Less arbitrary; more based on your personal taste.


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## rbolen

Sanjay, thank you for taking the time to respond. I will absolutely take this into consideration when I finally get to building and constructing my theater.


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## Pretorian

I am waiting for my first panels to arrive. I know where each panel will be placed in the room but not down to the exact placement. 
Should I sit in my MLP and take help doinf the mirror on wall trick to spot early reflections?

I will have two panels (floorstanding) on each side of my two mains. Two by the left wall and two by the right wall/window. 
I will have two panels for the ceiling somewhere between the fronts and the MLP. Can I do the mirror here too?
One bigger thicket monster bass trap just behind the MLP at the back wall. 
Floor to ceiling corner bass traps in the two front corners.


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## AndreNewman

Pretorian said:


> I am waiting for my first panels to arrive. I know where each panel will be placed in the room but not down to the exact placement.
> Should I sit in my MLP and take help doinf the mirror on wall trick to spot early reflections?
> 
> I will have two panels (floorstanding) on each side of my two mains. Two by the left wall and two by the right wall/window.
> I will have two panels for the ceiling somewhere between the fronts and the MLP. Can I do the mirror here too?
> One bigger thicket monster bass trap just behind the MLP at the back wall.
> Floor to ceiling corner bass traps in the two front corners.
> 
> View attachment 3138241
> 
> 
> View attachment 3138242
> 
> 
> View attachment 3138243


I like the couch, we've been looking for something like that, not in white though, what's it called, where did you get it?


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## squared80

Yes, you can just mirror everything.


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## Pretorian

AndreNewman said:


> I like the couch, we've been looking for something like that, not in white though, what's it called, where did you get it?


It is a Swedish company - Englesson. Model is Howard - a four seater.








Howard 4-Sits Svängd


Howard soffa 4-sits svängd - Hitta soffor och fåtöljer på nätet hos englesson.se




www.englesson.se


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## AndreNewman

Pretorian said:


> It is a Swedish company - Englesson. Model is Howard - a four seater.
> 
> 
> 
> 
> 
> 
> 
> 
> Howard 4-Sits Svängd
> 
> 
> Howard soffa 4-sits svängd - Hitta soffor och fåtöljer på nätet hos englesson.se
> 
> 
> 
> 
> www.englesson.se


Thanks, I can find some Englesson sofas available here in UK but not that one.

It's a design I had in my mind (slightly angled rather than right angles) but hadn't seen one like that until now, at least someone else had the same idea.


----------



## Pretorian

Just got my FIRST (yes there is more coming tomorrow) from GIK.





























I have not had time to test everything since the are more panels coming.

But wow. It is quiet when I sit in my sofa. Played a few songs and the bass... it is more and deeper and maybe too much. Not sure if this can ”happen” when installing treatment and bass traps?

I guess I need to run Audyssey again?

But the sound is tighter and more real in some way. Cant wait to try a movie.
You need to understand that I have had home theater since the 90s. This is my first time treating my room. It is an amazing feeling.
I will not mention the tears I got when playing the first tune.


----------



## nathan_h

Pretorian said:


> Just got my FIRST (yes there is more coming tomorrow) from GIK.
> 
> 
> View attachment 3140057
> 
> 
> View attachment 3140058
> 
> 
> View attachment 3140059
> 
> 
> I have not had time to test everything since the are more panels coming.
> 
> But wow. It is quiet when I sitin my sofa. Played a few songs and the bass... it is more and deeper and maybe too much. Not sure if the can ”happen” when installing treatment and bass traps.
> 
> I guess I need to run Audyssey again?
> 
> But the sound is tighter and more real in some way. Cant wait to try a movie.
> You need to understand that I have had home theater since the 90s. This is my first time treatung my room. It is an amazing feeling.
> I will not mention the tears I got when playing the first tune.



Yes will will definitely want to run Audyssey again after getting all the panels in place. 

It is possible that once you have 'clean up' the room/sound with the treatments that you will hear things (whether bass or otherwise) that was obscured before, and it might sound like "too much" or otherwise odd. Audyssey should automatically lower anything that is too high, now. After that, give your ears and brain a coupe weeks to adjust before deciding whether you like the new experience.


----------



## Pretorian

All panels are in place and I am really pleased. Just walking into my cinema creates this special feeling. It is funny that my Home Theater is now the most quiet room... until I press PLAY!

I need to do some tweaking since I redid the Audyssey setup after this install and the bass dissapeared and it sounds a little flat.


----------



## AndreNewman

Pretorian said:


> All panels are in place and I am really pleased. Just walking into my cinema creates this special feeling. It is funny that my Home Theater is now the most quiet room... until I press PLAY!


We find it makes the Cinema Room the nicest place in the house to sit and chat, my wife says it's a great place to be if you get a migraine headache.

I need to make some light coloured panels to put in our dining room, that gets very jangly (well it used to) when there are a lot people in there talking.



Pretorian said:


> I need to do some tweaking since I redid the Audyssey setup after this install and the bass dissapeared and it sounds a little flat.


This is a really common comment, usually it's because you had some big bass resonances before and now they are gone (or reduced anyway) give it a bit of time, you may realise there is now more detail in the sound than just BASS.




Pretorian said:


> View attachment 3141184


 I really like your room, it's not so often people post pictures of halfway rooms, not an all out Home Cinema but not a Living Room with some speakers and a TV either.

I wish I'd had these pictures when I was trying to explain my plans to my wife three years ago.

I call our room a convertible Cinema Room, we have a few more traps and curtains instead of blinds but the concept is similar.

So next I think you need some more corner traps on the floor either side of your center speaker, cover up those glaring skirting boards, maybe same on the ceiling corners above the screen? 

I would try toeing the left & right speakers in a bit, they may also benefit from being more in front of the corner traps. Now you have the traps, being closer in to the corners may put the corner reflection frequencies up into frequencies the traps can absorb better. Usually you want to be a bit away from the corners but having the traps there changes that.


----------



## Pretorian

AndreNewman said:


> We find it makes the Cinema Room the nicest place in the house to sit and chat, my wife says it's a great place to be if you get a migraine headache.
> 
> I need to make some light coloured panels to put in our dining room, that gets very jangly (well it used to) when there are a lot people in there talking.
> 
> 
> 
> This is a really common comment, usually it's because you had some big bass resonances before and now they are gone (or reduced anyway) give it a bit of time, you may realise there is now more detail in the sound than just BASS.
> 
> 
> 
> I really like your room, it's not so often people post pictures of halfway rooms, not an all out Home Cinema but not a Living Room with some speakers and a TV either.
> 
> I wish I'd had these pictures when I was trying to explain my plans to my wife three years ago.
> 
> I call our room a convertible Cinema Room, we have a few more traps and curtains instead of blinds but the concept is similar.
> 
> So next I think you need some more corner traps on the floor either side of your center speaker, cover up those glaring skirting boards, maybe same on the ceiling corners above the screen?
> 
> I would try toeing the left & right speakers in a bit, they may also benefit from being more in front of the corner traps. Now you have the traps, being closer in to the corners may put the corner reflection frequencies up into frequencies the traps can absorb better. Usually you want to be a bit away from the corners but having the traps there changes that.


Thanks for your comments! That helps me think about how to move forward. I will try both the toeing the fronts and move them closer to the corner. I will start with the panels I have now but remember what you are saying about corner traps on the floor beside the center.
This is just such a huge leap for me... getting these panels after all these years. And I am NOT regretting not getting them sooner. I just like it when you enhance/improve your room and not by "just" buying a new better more expensive speaker.


----------



## DarinS

DarinS said:


> Running some REW sims as I wait for my theater to be done.
> 
> I will be treating my front wall behind my AT screen with a 1" linacoustic - 3 mil - 1" linacoustic sandwich at the very least. On the surface absorption options, anyone have an idea of what my front wall correlates to?
> 
> I will also have an 11 feet deep, 15' wide riser that I am also building as a bass trap via @BIGmouthinDC suggestions. Any thoughts on how I can put that into the sim also?
> 
> As I play around with the absorption numbers the graph changes immensely!
> 
> Thanks,
> 
> Darin


I started a thread with the post quoted but have received no response. Any help or thoughts on what to put into the REW simulation is appreciated!


----------



## squared80

I've been looking around for good DIY diffuser designs. The Skyline diffuser should be easy enough. I also looked at modular and fractal diffusers. Some blueprints can be found at the link. I also attached a couple files.



Index of /wp-content/docs/diffusers


----------



## ajax-jp

My GIK acoustic treatments arrive tomorrow (FedEx willing).
I ordered:

8 Tri Traps w/scatter plates
6 244's (2 for each left and right wall, 2 for the back wall, not treating the ceiling yet)

I'm planning to take uncorrected (disabling Anthem ARC and my MiniDSP subwoofer config) room measurements before and after using REW and a u-mic 2.

I was planning to measure sweeps for the subs, 10-250, and then the speakers individually for the L/C/R, 250-20kHz from the main listening position.
Any other measurement recommendations or should I change my approach to something totally different?


----------



## nathan_h

I would measure the LCR full range even if you won’t end up using them that way.


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## ajax-jp

Turns out only 1 of the 7 packages arrived today.
Got 2 of these(244 impression, grey, black fabric)
The wood on these is pretty light reflective making them look more blonde than gray when on an angle (i just have it propped up against the wall for right now).
These 2 are for the back wall. The rest are the same pattern but black wood and grey fabric.

I included the SB16 for reference.


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## OJ Bartley

Pretorian said:


> I need to do some tweaking since I redid the Audyssey setup after this install and the bass dissapeared and it sounds a little flat.


I just wanted to drop a quick comment on this note. I had a similar experience when I was tweaking Audyssey, and I think it was when I turned on Sub2 that I was left with flat, and very light bass. It turned out the main speakers got set to "Large" somehow and when I set them back to "Small" it was better again.

Those new panels look awesome, by the way.


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## Pretorian

OJ Bartley said:


> I just wanted to drop a quick comment on this note. I had a similar experience when I was tweaking Audyssey, and I think it was when I turned on Sub2 that I was left with flat, and very light bass. It turned out the main speakers got set to "Large" somehow and when I set them back to "Small" it was better again.
> 
> Those new panels look awesome, by the way.


Thanks. I have my speakers set to Small but I increased the bass in level settings on my Denon and it sounds so much better. Sure, playing Tenet the bass is too much but playing a non Nolan movie it is great. Tenet is great too but it is a little too powerful.


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## hemiutut

Pretorian said:


> All panels are in place and I am really pleased. Just walking into my cinema creates this special feeling. It is funny that my Home Theater is now the most quiet room... until I press PLAY!
> 
> I need to do some tweaking since I redid the Audyssey setup after this install and the bass dissapeared and it sounds a little flat.
> View attachment 3141184
> 
> 
> View attachment 3141185


Hello Pretorian
First of all, congratulations for putting acoustic treatment in your room, in my opinion it is the parameter that needs to be taken care of the most + a powerful and customizable equalization.

Do you have measurements with Room EQ Wizar for example?
It is simply to see the acoustics of the room.

How far away is the listening point?
Can you explain what acoustic treatment you have in model and quantity?


Written with Google translator.

Greetings


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## Aliens

I'm moving to a new home, so yesterday I removed 12 acoustic panels in my entertainment room. WOW! The highs dramatically increased, and the bass decreased as well. There is a real sense of hollowness. I recall when I added these how much of a difference it made, but once removed, it's a stark reminder of what they do. Of course, if I re-calibrated the room it would help, but not to this extreme. If you are on the fence about adding them, don't hesitate, the difference is stunning. I made all 12 of mine for around $500.


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## Pretorian

hemiutut said:


> Hello Pretorian
> First of all, congratulations for putting acoustic treatment in your room, in my opinion it is the parameter that needs to be taken care of the most + a powerful and customizable equalization.
> 
> Do you have measurements with Room EQ Wizar for example?
> It is simply to see the acoustics of the room.
> 
> How far away is the listening point?
> Can you explain what acoustic treatment you have in model and quantity?
> 
> 
> Written with Google translator.
> 
> Greetings


I have not yet done any REW. I will do it in the future when I have the knowledge. 
I sit 3,5 meters from the screen. 
I have treatment from GIK. 
Bass traps in the front corners. (Four corner bass traps)
Panels for first reflections on each side of the front speakers x2 (four panels)
Two panels on the ceiling for first reflections 
One extra thick bass trap behing MLP.


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## niterida

I posted this as its own topic but haven't received any replies so I thought I might post it here as well :

I have seen a general rule of thumb to have 15% absorption and 25% diffusion in a listening room to prevent it being too lively or too dead.
But I was thinking about the new 3d Immersive audio formats and since they work on direct sound being placed all around in the entire 3d space of a room, surely absorption is more important to stop reflections affecting this 3d placement and conversely since direct sound is being played from all around you anyway then diffusion is not important at all ?
Maybe the 15/25% rule is a leftover from stereo or early 5.1 days when you wanted sound to be diffused to give a sense of a larger soundfield or more ambience ?
I have a 7.x.4 setup in a 6.2m x 4.3m x 2.7m brick room with carpeted floors and absorbers for all 3 front speakers on the left and right walls and ceiling, with no diffusion anywhere. The sound improved dramatically when I added the absorbers and the imaging, soundfield and ambience is exceptional (I haven't measured it but have compared it multi thousand dollar demo rooms) so I am thinking that immersive sound formats don't need as much diffusion if at all ?


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## nathan_h

Really depends on the size of the room, the dispersion of the speakers, and so on.

But yes if you can only do one thing, and you cannot do acoustic measurments, then some absorption is the most important first step in a domestic room. As you have noticed, it can really clean things up. 

That being said, if one is being very particular (ie measuring for a precise rt60 value, for example) then you would want all the tools available to achieve your goal and diffusion likely has a role to play to get the right decay times and other measurable attributes in line.

This of course is way beyond the rule of thumb targets like “15% absorption plus 15% diffusion” which are fine ballpark figures but not really the goal…..just likely to get one close, at which point measurement and positioning and fine tuning and eq and bass management and time alignment etc etc come in to play…..all of which benefit from skill with a hundred dollar measurement microphone and the free powerful REW software.


----------



## niterida

nathan_h said:


> Really depends on the size of the room, the dispersion of the speakers, and so on.
> 
> But yes if you can only do one thing, and you cannot do acoustic measurments, then some absorption is the most important first step in a domestic room. As you have noticed, it can really clean things up.
> 
> That being said, if one is being very particular (ie measuring for a precise rt60 value, for example) then you would want all the tools available to achieve your goal and diffusion likely has a role to play to get the right decay times and other measurable attributes in line.
> 
> This of course is way beyond the rule of thumb targets like “15% absorption plus 15% diffusion” which are fine ballpark figures but not really the goal…..just likely to get one close, at which point measurement and positioning and fine tuning and eq and bass management and time alignment etc etc come in to play…..all of which benefit from skill with a hundred dollar measurement microphone and the free powerful REW software.


I was thinking more along of the sound effects / soundfield etc of immersive audio - in other words recreating exactly what the mixer intended, rather than trying to get diffuse sounds to create ambience or illusion of bigger room etc. This was assuming that EQ, speaker placement and the absorption in the room already addressed the imaging, RT and reflection issues. 
So assuming everything else is optimal - do immersive audio formats require less, little or no diffusion to recreate what the mixer intended since we now have at least 9 and more likely 11 speakers all around that, I imagine would work best as direct radiators with absolutely no reflections AND no diffusion ?


----------



## nathan_h

Again, it is easy to check via measuring the room. Some rooms require very little diffusion. And in most rooms, some absorption gets you the most bang for the buck, and following the 15 or 20% target for absorption is not a bad starting place, especialy if you cannot measure the room.

Then we get into the whole debate of the depth of the absorption. The safe answer is six inches of fiberglass minimum to absorb in a consistent fashion down to where the subwoofers take over. But again, _measuring _what you have achieved and making corrections based on the measurement is the way to get it right.

The goal here is not necessarily spacious sound but the appropriate RT60 behavior. And even that is a little nebulous since the smaller the room, the shorter the RT60 target (in general) to sound "right".

Absorption, depth of absorption and its impact at different frequencies, placement of panels, the dispersion characteristics of the particular speakers in use, use of diffusion, the type and placement of diffusion, the placement of the listener, the placement of the speakers relative to room boundaries, the size of the room, correct bass management and control of room modes......these are all variables that it is useful to be able to manipulate to get the right in room response, including in room response in the time domain.

---

And, as you have found, the biggest step forward is to throw some absorption on the walls. But that's maybe a 50% solution. A huge step forward in most rooms, but not the ultimate solution. To get closer to ultimate, measurement is necessary, and being willing or able to adjust all the variables I listed is key.

There is a reason the professionals measure every room they work on. No one size fits all, and even rooms of similar dimensions can sound different based on construction techniques, the placement of stud bays in the walls, whether those are filled with air or other material, how thick the drywall is, whether the walls are drywall at all, what the furniture is like, where the furniture is located, whether they are optimizing for a single seat, a single row of seats, or multiple rows of seats -- in addition to the obvious stuff like the specific speakers in use, type of video screen, and so on.


----------



## sdurani

niterida said:


> I am thinking that immersive sound formats don't need as much diffusion if at all ?


Going from 5.1 to 11.1 (7.1.4) means you'll be hearing more direct sound vs reflections than previously, so you'd need less treatment in general. Rather than percentages, I would place treatment based on direction. For example, I prefer absorption across the front wall (at least between the L/C/R speakers) to minimize reflections that could mess up the critical front soundstage, since they will be coming from the same direction as my front speakers. I don't absorb side wall early reflections because they widen the soundstage and aid in spaciousness. YMMV. In the surround field, I prefer to take the sting out of annoying reflections by using diffusion rather than absorption, so that the energy is spread around rather than removed, resulting in a more blended and ambient surround field. Same with height speakers. Not sure what percentage of absorption vs diffusion that comes out to.


----------



## DougUSMC

Every time I think I'm finally starting to understand acoustic treatment fundamentals I come to this thread, read a bit, and have my mind blown all over again...


----------



## niterida

sdurani said:


> Going from 5.1 to 11.1 (7.1.4) means you'll be hearing more direct sound vs reflections than previously, so you'd need less treatment in general. Rather than percentages, I would place treatment based on direction. For example, I prefer absorption across the front wall (at least between the L/C/R speakers) to minimize reflections that could mess up the critical front soundstage, since they will be coming from the same direction as my front speakers. I don't absorb side wall early reflections because they widen the soundstage and aid in spaciousness. YMMV. In the surround field, I prefer to take the sting out of annoying reflections by using diffusion rather than absorption, so that the energy is spread around rather than removed, resulting in a more blended and ambient surround field. Same with height speakers. Not sure what percentage of absorption vs diffusion that comes out to.


I have my AT screen acting as an absrber do the front wall is covered. 
I absorbed the 1st reflections on the side walls and it cleaned up the sound greatly - solid brick walls made it ring and echo before - soundstage is very wide but my speakers are out at 60deg.
I am pretty happy with my setup up as is but need to do more in the rear and can't really fit much diffusion and was hoping to get away with none at all. Looks like I will need a little bit back there at least.


----------



## cheyneb25

DougUSMC said:


> Every time I think I'm finally starting to understand acoustic treatment fundamentals I come to this thread, read a bit, and have my mind blown all over again...


I feel you there man... I've been learning online in forums and respected websites/Youtube channels about room acoustics, speaker placement, EQ, multi-sub, etc. etc. for over 6 yrs now, and while I've made lots of good progress with everything, my knowledge has probably barely scratched the surface of what can be done. This rabbit hole that we all love is hella deep...lol.


----------



## cheyneb25

Speaking of the quest to further one's knowledge, I wanted to run my line of thinking by the knowledgeable peeps here on this thread to see if my acoustic reasoning on something was sound. My semi-dedicated theater room has a wall that running down the entire left side - the back half of it is brick, the front half is drywall, and all of it is below ground level; however, the right side of the room keeps expanding further out every so many feet (see attached pic of the den layout). 

The sound from movies and music has always sounded like it was just a wee bit stronger/more spacious coming from the left side of the room, I assume (at least in part) from speaker/wall interaction and the reflections that I'm getting from that wall, so my approach to combat this and even the sound out has been to put acoustic panels/bass traps spaced out on the left side wall, as well as experimenting with implementing a 'sliding wall' on the right back side of the room to create a good surface for higher frequency sound to reflect off of. 

Each of the 4 sliding sections that will make up the 'wall' would comprise of three 1/4" thick HDF panels from Lowes (think white markerboard) that are bonded together to form one 3/4" think panel. The markerboard side is facing in towards the listening area to provide a smooth flat barrier for the higher frequency sound to reflect off of, and I chose HDF panels because they had a high density (for maximum reflection) and the markerboard surface seems to do well with reflecting sound.

The 'wall' project is in its proof of concept stage right now so I only have some of the panels hanging from simple hooks in the ceiling at the moment, and in the included pics that I took only one set of the panels is full length like they all would be and go all the way down to the floor. If my idea is a sound one then my next step is to get the rest of the panels I need and then move forward with installing a simple track system on the ceiling to mount them from and make a telescoping 'wall' to match the other wall on the left side. The thought is to be able to extend it out for when movies/music are being enjoyed and just collapse it back down again to open the room up when its being used to entertain people in the back half area.

I'm still a relative newbie when it comes to effectively using REW, but at least to my ears, the sound has improved after the latest round of changes I made. Right now I just use REW with my Mindsp HD to get my 5 subs all talking nicely with each other and I haven't installed ASIO for it (I use a workaround from the Home Theater Gurus channel on Youtube to work on my bass), but eventually, my goal is to learn enough with REW to tackle the rest of my speaker setup, install ASIO, and then be able to use the measurements to help me with narrowing down and fixing the rest of my acoustical issues in the room.

Curious to hear people's thoughts on the 'wall' idea, cheers everyone!


----------



## niterida

cheyneb25 said:


> Speaking of the quest to further one's knowledge, I wanted to run my line of thinking by the knowledgeable peeps here on this thread to see if my acoustic reasoning on something was sound. My semi-dedicated theater room has a wall that running down the entire left side - the back half of it is brick, the front half is drywall, and all of it is below ground level; however, the right side of the room keeps expanding further out every so many feet (see attached pic of the den layout).
> 
> The sound from movies and music has always sounded like it was just a wee bit stronger/more spacious coming from the left side of the room, I assume (at least in part) from speaker/wall interaction and the reflections that I'm getting from that wall, so my approach to combat this and even the sound out has been to put acoustic panels/bass traps spaced out on the left side wall, as well as experimenting with implementing a 'sliding wall' on the right back side of the room to create a good surface for higher frequency sound to reflect off of.
> 
> Each of the 4 sliding sections that will make up the 'wall' would comprise of three 1/4" thick HDF panels from Lowes (think white markerboard) that are bonded together to form one 3/4" think panel. The markerboard side is facing in towards the listening area to provide a smooth flat barrier for the higher frequency sound to reflect off of, and I chose HDF panels because they had a high density (for maximum reflection) and the markerboard surface seems to do well with reflecting sound.
> 
> The 'wall' project is in its proof of concept stage right now so I only have some of the panels hanging from simple hooks in the ceiling at the moment, and in the included pics that I took only one set of the panels is full length like they all would be and go all the way down to the floor. If my idea is a sound one then my next step is to get the rest of the panels I need and then move forward with installing a simple track system on the ceiling to mount them from and make a telescoping 'wall' to match the other wall on the left side. The thought is to be able to extend it out for when movies/music are being enjoyed and just collapse it back down again to open the room up when its being used to entertain people in the back half area.
> 
> I'm still a relative newbie when it comes to effectively using REW, but at least to my ears, the sound has improved after the latest round of changes I made. Right now I just use REW with my Mindsp HD to get my 5 subs all talking nicely with each other and I haven't installed ASIO for it (I use a workaround from the Home Theater Gurus channel on Youtube to work on my bass), but eventually, my goal is to learn enough with REW to tackle the rest of my speaker setup, install ASIO, and then be able to use the measurements to help me with narrowing down and fixing the rest of my acoustical issues in the room.
> 
> Curious to hear people's thoughts on the 'wall' idea, cheers everyone!


I would make the RHS a pemanent wall as far back as your rear surrounds.


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## DougUSMC

cheyneb25 said:


> I feel you there man... I've been learning online in forums and respected websites/Youtube channels about room acoustics, speaker placement, EQ, multi-sub, etc. etc. for over 6 yrs now, and while I've made lots of good progress with everything, my knowledge has probably barely scratched the surface of what can be done. This rabbit hole that we all love is hella deep...lol.


I'm not even "kinda' kidding". If you've ever read my theater build threads, you can see that I learned and upgraded a LOT in the 1.0 and 1.5 versions of my room. I changed SO much in how I designed and approached the room.

I adjusted the entry and overall flow. I changed the rack location, PJ hang, seats. I added a BOSS riser and changed the height of the main. Lighting was redesigned, GOM panels, doors, DD + GG, etc.

One thing that I didn't change: Hired a pro for the acoustic treatments. Thanks @Nyal Mellor !!


----------



## Mashie Saldana

DougUSMC said:


> One thing that I didn't change: Hired a pro for the acoustic treatments. Thanks @Nyal Mellor !!


Did you end up with 50% absorption and 50% diffusion on the side/rear walls and ceiling?


----------



## tidwelr1

DougUSMC said:


> I'm not even "kinda' kidding". If you've ever read my theater build threads, you can see that I learned and upgraded a LOT in the 1.0 and 1.5 versions of my room. I changed SO much in how I designed and approached the room.
> 
> I adjusted the entry and overall flow. I changed the rack location, PJ hang, seats. I added a BOSS riser and changed the height of the main. Lighting was redesigned, GOM panels, doors, DD + GG, etc.
> 
> One thing that I didn't change: Hired a pro for the acoustic treatments. Thanks @Nyal Mellor !!


Pics?


Sent from my iPhone using Tapatalk


----------



## DougUSMC

tidwelr1 said:


> Pics?


You can see the pictures of his plan in my build thread HERE.


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## Mashie Saldana

DougUSMC said:


> You can see the pictures of his plan in my build thread HERE.


Nice, you posted this just as I had reached that page in your thread. That is a typical Nyal Mellor design, very nice.


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## cheyneb25

niterida said:


> I would make the RHS a pemanent wall as far back as your rear surrounds.


I did consider that approach strongly as well... Extending that existing right wall further back makes a whole lot of sense to me as well, and down the road I may eventually go that route.

However, I had to compromise with the wife on this and having a sliding wall appealed to her because it wouldn't be there all the time, so it was the next best solution I could think of. 

Because the laundry room/HVAC area and a bathroom are in the adjoining areas that are walled off, redoing the walls would be pretty in-depth and a little outside of what I'm willing to spend on it (at the moment). Redoing the walls would be ideal, but working around the existing plumbing/gas/HVAC infrastructure located on those walls would be difficult.


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## etherealsound

Hello, not sure if this is the right thread for this but I had a question regarding bass traps. So I have some roxul safe n sound and plan on making some corner bass traps from floor to ceiling. However, I've heard of concerns regarding the safety of the material and so to err on the side of caution, I have considered using a fabric to cover the bass trap that is NOT acoustically transparent. I figure that for something like low frequency energy, acoustically transparent material will not really matter that much and the bass trap will still retain most of it's intended purpose while not allowing mineral wool particles to go airborne. Can someone let me know if this would work or if my fears are unfounded? Thank you.


----------



## AndreNewman

etherealsound said:


> Hello, not sure if this is the right thread for this but I had a question regarding bass traps. So I have some roxul safe n sound and plan on making some corner bass traps from floor to ceiling. However, I've heard of concerns regarding the safety of the material and so to err on the side of caution, I have considered using a fabric to cover the bass trap that is NOT acoustically transparent. I figure that for something like low frequency energy, acoustically transparent material will not really matter that much and the bass trap will still retain most of it's intended purpose while not allowing mineral wool particles to go airborne. Can someone let me know if this would work or if my fears are unfounded? Thank you.


i've used Knauf Ecosse slabs for a couple of related reasons.

They claim that the surface of the mineral wool is sealed, a heat seal something like ironing I understand and that it doesn't shed particles like some of the competitors. I have certainly noticed that there is very little, almost no dust from the slabs, well until you cut them. For my second set of bass traps I changed the external sizes a little so I never needed to cut the slabs.

Knauf also claim there is no outgassing of formaldehyde or other volatiles when the material is new. I certainly have not noticed any smell from the panels, my wife is sensitive to anything like that and she didn't detect anything either.

An American friend who was building panels a few month before me decided to leave his slabs laid out in his garage for a few weeks until they stopped smelling before he started building panels.


----------



## Mondo Rock

As of 2021, what is the latest and greatest absorbent material for DIY bass traps and acoustic panels?


----------



## Soulburner

Mondo Rock said:


> As of 2021, what is the latest and greatest absorbent material for DIY bass traps and acoustic panels?


I assume you mean broadband. Knauf ECOSE seems to be a top pick.









Knauf Insulation - GIK Acoustics


24" x 48" x 2" sold at 6 sheets per pack. Tested and is certified to meet the EUCEB requirements. This Acoustical Board is made from inorganic glass mineral wool preformed into boards with ECOSE® Technology. Formaldehyde-Free, odorless, UL Environment GREENGUARD and GREENGUARD Gold standard...




www.gikacoustics.com







https://www.ecosetechnology.com/en


----------



## nathan_h

Mondo Rock said:


> As of 2021, what is the latest and greatest absorbent material for DIY bass traps and acoustic panels?


It’s still fiberglass. Details about small variations:



https://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## ajax-jp

Been a little busy, but I figured I'd post some pictures of the room after I got all of the treatments up.
I took a lot of measurements along the way and lost a few of them....
All in all, I installed 10 panels, 2 on the back wall, 2 tri-traps stacked in each corner and 2 on each side wall.

To sum up the difference, it was jarring.
Quiet vocals in movies completely cleared up. This was probably my biggest complaint going in, that vocals, especially at low volumes, were muddy and hard to understand.

Loud listening is no longer fatiguing. (I had always just thought I had it too loud). 

There is much less sound hanging in the room. This was immediately noticeable when I added the treatments at the early reflection points (treatments came in in multiple shipments and went on the walls in this order: back, left+right, lower corners, upper corners) Instruments now stop and start quickly and cleanly. You can hear the gaps instead of notes hanging in the room filling them. Imaging improved because of this providing much more 3 dimensional sound on stereo listening. Soundstage is noticeably wider and very open sounding.

LFE cleaned up quite a bit, and I was actually able to turn DOWN all of the amps and get the same level of output or better. I had a null down at 47hz that is completely gone. I still have a null at 66hz but it's ~6db, nowhere near as bad as the 15db loss I had at 47hz. It might be something I can work out w/the mini-dsp or just adjusting the positions of the subs (I only have 1 in the rear because I have nowhere to put a second one).

Overall, the room is noticeably quieter, and a ton cleaner. And best of all, my wife can tell the difference, so I'm not totally losing my mind.


----------



## anjunadeep

Hello acoustics gurus! I'm in the planning stage of building a small theater. This is the layout I currently have... my hope is to do an acoustically transparent screen and have the room be well treated.

One thing about the door placement is I really am only 5-6" off the back wall, is that going to be enough for bass trapping? The front I can line the entirety of behind the screen with insulation, but the back I can't go as thick in that corner by the door. How big of an issue will this be? I tried the door in the middle (where the AV rack is) and it just makes entering the theater from the rest of the space really weird.

Also can I use regular ol' pink insulation or would I need to buy that Owens Corning 703 stuff?

Edit: I also thought of shifting the door slightly forward (making that closet cabinet a bit smaller) and then shifting the chairs forward. They're currently like 10ft back... I could maybe go to 8' 6" or something with a 130" screen? I want to do 9.4.4 so lots of parts.


----------



## nathan_h

anjunadeep said:


> Hello acoustics gurus! I'm in the planning stage of building a small theater. This is the layout I currently have... my hope is to do an acoustically transparent screen and have the room be well treated.
> 
> One thing about the door placement is I really am only 5-6" off the back wall, is that going to be enough for bass trapping? The front I can line the entirety of behind the screen with insulation, but the back I can't go as thick in that corner by the door. How big of an issue will this be? I tried the door in the middle (where the AV rack is) and it just makes entering the theater from the rest of the space really weird.
> 
> Also can I use regular ol' pink insulation or would I need to buy that Owens Corning 703 stuff?
> 
> Edit: I also thought of shifting the door slightly forward (making that closet cabinet a bit smaller) and then shifting the chairs forward. They're currently like 10ft back... I could maybe go to 8' 6" or something with a 130" screen? I want to do 9.4.4 so lots of parts.
> 
> 
> View attachment 3164690


Looks like a great space.

I made the mistake of having the door in the back of the room on my last theater space. If I were you, I'd flip the front and back wall if possible.

That being said, in terms of treatment behind you, if you have space for six inch panels, that REALLY helps. But if you only have six or so inches you will not have nearly enough space for surround back speakers to sound good. You'll want a couple of feet minimum, and even then might need to use BIpole speakers for read surrounds to get adequate dispersion.


----------



## sdurani

anjunadeep said:


> One thing about the door placement is I really am only 5-6" off the back wall, is that going to be enough for bass trapping? The front I can line the entirety of behind the screen with insulation, but the back I can't go as thick in that corner by the door. How big of an issue will this be?


5-6 inches of absorption isn't going to do any effective bass trapping. If you look at AVS threads about single bass arrays, where the back wall is used as a bass absorber, you'll see that a few feet (not inches) of absorption is needed to absorb bass frequencies in the subwoofer range. According to absorption coefficient charts, 6 inches of rigid fiberglass (OC703) makes for broadband absorption that is effective down to around 100Hz or so. Your best bet for addressing bass in the subwoofer range is placement & EQ.

Rather than cover the back wall corner to corner, I would just do the middle half (i.e., area directly opposite the Centre speaker). Three 2'x4' pieces of 6" OC703 should do it (for a total area of 6'x4'). Mount your Rear speakers on both sides of the absorption and use diffusion or leave bare the rest of the back wall.


----------



## anjunadeep

nathan_h said:


> Looks like a great space.
> 
> I made the mistake of having the door in the back of the room on my last theater space. If I were you, I'd flip the front and back wall if possible.
> 
> That being said, in terms of treatment behind you, if you have space for six inch panels, that REALLY helps. But if you only have six or so inches you will not have nearly enough space for surround back speakers to sound good. You'll want a couple of feet minimum, and even then might need to use BIpole speakers for read surrounds to get adequate dispersion.


Thanks! Yeah, I'm excited. Actually running into projector throw issues though. Like with the screen wall and distance of the projector lens off the back wall, I don't have a whole lot of throw to make a big image with a JVC NX7 or something (even worse with a NX5). Some members told me there is a lens I can buy and put in front of it but I donno...

I actually looked at having the door in the front but it interfered with the screen wall and front wides ._. 
Is the door at the back bad for ergonomic reasons or just placement of acoustic panels?

I'll be off the back wall a good ways, at least in the row that matters. The screen in that sketch is 16" off the front wall, and then the center recliner is 9ft beyond that.



sdurani said:


> 5-6 inches of absorption isn't going to do any effective bass trapping. If you look at AVS threads about single bass arrays, where the back wall is used as a bass absorber, you'll see that a few feet (not inches) of absorption is needed to absorb bass frequencies in the subwoofer range. According to absorption coefficient charts, 6 inches of rigid fiberglass (OC703) makes for broadband absorption that is effective down to around 100Hz or so. Your best bet for addressing bass in the subwoofer range is placement & EQ.
> 
> Rather than cover the back wall corner to corner, I would just do the middle half (i.e., area directly opposite the Centre speaker). Three 2'x4' pieces of 6" OC703 should do it (for a total area of 6'x4'). Mount your Rear speakers on both sides of the absorption and use diffusion or leave bare the rest of the back wall.


Thanks. I actually wanted to go with four sealed subwoofers at 1/4 placement off either wall (front and back, the harman paper layout). Four subs also are the ticket in my living room, so i'm kinda never going back to less than 4 in a room. In my experience it just makes getting a good response much easier. 6" of absorption off the back wall should be no problem, and I like the center placement idea as it allows me to have subs on either side a bit tighter to the wall.


----------



## nathan_h

anjunadeep said:


> Thanks! Yeah, I'm excited. Actually running into projector throw issues though. Like with the screen wall and distance of the projector lens off the back wall, I don't have a whole lot of throw to make a big image with a JVC NX7 or something (even worse with a NX5). Some members told me there is a lens I can buy and put in front of it but I donno...


I feel your pain. I have run into the same issue in my current temporary room. I solve it be going with a slightly smaller screen than I wanted for now.

The one lens option I am familiar with is using a anamorphic lens (careful, some squeeze the top and bottom rather than spreading the sides) to stretch the image sideways, letting you use a 2.35:1 screen that is as tall as your throw range limits you to...but wider for a 2.35:1 image area. 

I chose not to do this because in my real room I won't need the lens and it was hard to justify a few grand for such a lens in a temporary room.

Maybe there are other lens options I dont know about. If you learn about them, please share what you learn.



> I actually looked at having the door in the front but it interfered with the screen wall and front wides ._.
> Is the door at the back bad for ergonomic reasons or just placement of acoustic panels?


Mostly aesthetics and but yes it might well put the door where front wides would go if you are using them. Often, the worst issue is that you need to put a diffusion or absorption or combo panel on the door. But if you are using wides, that's more complicated!


> I'll be off the back wall a good ways, at least in the row that matters. The screen in that sketch is 16" off the front wall, and then the center recliner is 9ft beyond that.
> 
> Thanks. I actually wanted to go with four sealed subwoofers at 1/4 placement off either wall (front and back, the harman paper layout). Four subs also are the ticket in my living room, so i'm kinda never going back to less than 4 in a room. In my experience it just makes getting a good response much easier. 6" of absorption off the back wall should be no problem, and I like the center placement idea as it allows me to have subs on either side a bit tighter to the wall.


Yeah, in the old days, people tried to build giant thick bass traps and sound you needed several feet to deal with bass waves...and then Harman (and others) showed that you don't need to trap bass if you use multiple subs.....that with four subs in a sealed rectangular room you can pretty much kill all the dips in response and knock down any peaks (which are consistent from seat to seat because of the multiple subs) and get flat response, all without bass traps.

By the way, if you have room for ported subs, you'll get lots of nice headroom in terms of output. The downside is just their size. But if you are in the "budget' category (1k and under per sub) then the tradeoff is worth it if you have space. (Above that budget, you can start to get sealed subs that can move tons of air, and eventually afford a sealed sub that can outperform a ported one in terms of output, by roughly doubling your subwoofer budget.)

The six inch panels on the back well is based on the idea of attenuating (trapping) the full frequency response ABOVE the region where the subs are working there magic. It effectively kills reflects on that back wall across the entire frequency band above 80/100hz, greatly cleaning up the sound in the room. 

Grimani likes to put the panels behind all the seating positions but then use diffusion on the edges (still talking about the back wall here) to retain indirect reflections in a constructive way. This is somewhat dependent on room size, seating positions, dispersion of the speakers (and their locations) etc.


----------



## anjunadeep

nathan_h said:


> I feel your pain. I have run into the same issue in my current temporary room. I solve it be going with a slightly smaller screen than I wanted for now.
> 
> The one lens option I am familiar with is using a anamorphic lens (careful, some squeeze the top and bottom rather than spreading the sides) to stretch the image sideways, letting you use a 2.35:1 screen that is as tall as your throw range limits you to...but wider for a 2.35:1 image area.
> 
> I chose not to do this because in my real room I won't need the lens and it was hard to justify a few grand for such a lens in a temporary room.
> 
> Maybe there are other lens options I dont know about. If you learn about them, please share what you learn.


I was directed to this: HD ScreenStar Lenses - ScreenStar® Conversion Lenses | Navitar

It says 1080p, but the members claimed it was okay for 4k as well... Not sure. 

2.35:1 helps the throw problem because you're zoomed in farther it seems, but man so many 2.35:1 movies now have scenes that are IMAX or, far more commonly, have subtitles in the letterboxing. I mean I was watching Jungle Cruise the other day and the subtitles in the Spanish scenes were in the letterboxes.




nathan_h said:


> Mostly aesthetics and but yes it might well put the door where front wides would go if you are using them. Often, the worst issue is that you need to put a diffusion or absorption or combo panel on the door. But if you are using wides, that's more complicated!


Yeah, I'd like to.. here is my "rough" speaker layout:









_edit_ door would also be nice at the front of the room since then don't have to walk by the recliners. Those recliners aren't too scale really, and worse comes to worse I get a couch instead. Just not sure how to work it really, as the front stage would stick out a lot. I mean I can cheat some space on that door... It will really depend how far my screen wall has to stick out



nathan_h said:


> Yeah, in the old days, people tried to build giant thick bass traps and sound you needed several feet to deal with bass waves...and then Harman (and others) showed that you don't need to trap bass if you use multiple subs.....that with four subs in a sealed rectangular room you can pretty much kill all the dips in response and knock down any peaks (which are consistent from seat to seat because of the multiple subs) and get flat response, all without bass traps.


Oh yeah, for sure. I'm going with quad subwoofers. It should also allow me to use less depth, and added bonus for aesthetics.



nathan_h said:


> By the way, if you have room for ported subs, you'll get lots of nice headroom in terms of output. The downside is just their size. But if you are in the "budget' category (1k and under per sub) then the tradeoff is worth it if you have space. (Above that budget, you can start to get sealed subs that can move tons of air, and eventually afford a sealed sub that can outperform a ported one in terms of output, by roughly doubling your subwoofer budget.)


I have JTR RS1 sealed subs currently. I really like high output sealed stuff as I never hear the port. It is hard on the budget but I think it is worth it. RS1s may be overkill for that room though, considering 2x have enough output to make my giant open living room sound like a theater (4x is just to even the response). But, if not I may just get four more for this theater as well. I haven't really thought too much about speakers yet though.. was going to browse CEDIA a bit in a few weeks and low profile subs was on my list.



nathan_h said:


> The six inch panels on the back well is based on the idea of attenuating (trapping) the full frequency response ABOVE the region where the subs are working there magic. It effectively kills reflects on that back wall across the entire frequency band above 80/100hz, greatly cleaning up the sound in the room.
> 
> Grimani likes to put the panels behind all the seating positions but then use diffusion on the edges (still talking about the back wall here) to retain indirect reflections in a constructive way. This is somewhat dependent on room size, seating positions, dispersion of the speakers (and their locations) etc.


Ah okay that makes sense. That's what I'll do!


----------



## anjunadeep

nathan_h said:


> Mostly aesthetics and but yes it might well put the door where front wides would go if you are using them. Often, the worst issue is that you need to put a diffusion or absorption or combo panel on the door. But if you are using wides, that's more complicated!


Thanks for this idea... playing with it now and by curving the "hidden subwoofer stage". This allows for better acoustic treatment in the rear if I want. That's the screen off the wall 16" and the subwoofer stage off 24". I mean I might not even need the sub stage if I can find low profile subs.. maybe a stage that is two feet off the floor will look weird I donno.


----------



## nathan_h

You know now that I look at it again I suspect either config works and maybe letting those awesome subs determine the orientation because of their size is totally understandable!


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## anjunadeep

nathan_h said:


> You know now that I look at it again I suspect either config works and maybe letting those awesome subs determine the orientation because of their size is totally understandable!


I do like walking into the seats more, since the room is fairly thin, and it makes acoustic treatments a bit easier. As long as I can keep front wides, which, it seems I can if I'm careful. The subs are TBD really.. I have the JTRs in my living room but they'll be staying there so I can either get 4x more of those or get something else that is thinner. The JTR RS1s aren't super big, 18" deep, pretty reasonable. I'm actually a bit afraid 4x of those would be so overkill in here I'd just be wasting money. 

If the back wall became like the flipped design, then should I build more thickness in the rear absorption? 

Another thing I'm debating is carpet or tile on the floor. My fear is if I put absorption on the front, rear, and sidewalls (partial), that I might overdeaden the room with carpet. Maybe hardwood floor and do some treatments on the ceiling? I was reading carpet absorption is a bit uneven too. Hardwood is sure easier if I spill lol...


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## niterida

@anjunadeep 2 questions for you :
1. Can you not enter via the AV Rack and put the rack where the door is ?
2. Why have you drawn your front heights so far forward from the seats ? They should be the same distance as your rear heights from your ears.


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## anjunadeep

niterida said:


> @anjunadeep 2 questions for you :
> 1. Can you not enter via the AV Rack and put the rack where the door is ?
> 2. Why have you drawn your front heights so far forward from the seats ? They should be the same distance as your rear heights from your ears.


Hi!

1. I originally had the door there but it didn't lay out well in the other room - like to cross into the entrance you'd have to take a weird path. It doesn't lay out well elsewhere, basically. It's how I originally had it though. Maybe there is a way to re-organize things in the other room to make that work but, it wasn't looking likely. 
2. I just sketched/eyeballed these to give an idea real quick as I was chatting in this thread today, it's not to scale or anything. I just kinda popped those up there to show I wanted four in the ceiling but didn't work on getting the placement close. Good catch though!


----------



## fattire

anjunadeep said:


> I do like walking into the seats more, since the room is fairly thin, and it makes acoustic treatments a bit easier. As long as I can keep front wides, which, it seems I can if I'm careful. The subs are TBD really.. I have the JTRs in my living room but they'll be staying there so I can either get 4x more of those or get something else that is thinner. The JTR RS1s aren't super big, 18" deep, pretty reasonable. I'm actually a bit afraid 4x of those would be so overkill in here I'd just be wasting money.
> 
> If the back wall became like the flipped design, then should I build more thickness in the rear absorption?
> 
> Another thing I'm debating is carpet or tile on the floor. My fear is if I put absorption on the front, rear, and sidewalls (partial), that I might overdeaden the room with carpet. Maybe hardwood floor and do some treatments on the ceiling? I was reading carpet absorption is a bit uneven too. Hardwood is sure easier if I spill lol...


If you’re DIY capable, GSG has a “behind the screen” kit available in several dimensions depending on what you need. It’s a nice design as the ports are to the sides rather than the front. So not only are they built to fit, the port air won’t move the screen around. 

IIRC they are 16” deep and vary in height and width. 

Just a thought. I don’t own any of their builds.


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## sdurani

anjunadeep said:


> If the back wall became like the flipped design, then should I build more thickness in the rear absorption?


Keep the same thickness for absorption no matter where you place it in the room. You want the panels to absorb broadband, not absorb high frequencies more than low frequencies (making them an unintended tone control). Only difference would be amount: middle half of back wall vs most or all of front wall.


> Another thing I'm debating is carpet or tile on the floor.


Carpet, with thick padding. Won't absorb enough to deaden the room.


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## anjunadeep

sdurani said:


> Keep the same thickness for absorption no matter where you place it in the room. You want the panels to absorb broadband, not absorb high frequencies more than low frequencies (making them an unintended tone control). Only difference would be amount: middle half of back wall vs most or all of front wall. Carpet, with thick padding. Won't absorb enough to deaden the room.


Okay so even if I have corners where I can put thicker bass traps, just stick with 6" everywhere? I mean I was thinking behind the screen I could go pretty thick... With this layout I could do 6" for anything exposed on the walls, but behind the screen go more like 10"+ and the rear wall corners could go thicker as well. I guess with the four subs I don't need to go thicker than 6" though since that covers down to the crossover region so I'd just be wasting insulation?

Can I over-deaden the room?


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## nathan_h

It won’t really hurt to go thicker.


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## sdurani

anjunadeep said:


> Okay so even if I have corners where I can put thicker bass traps, just stick with 6" everywhere?


Yes, for broadband absorption of reflections from your speakers. To absorb deep bass from your subs, you'll need 3'-4' feet of absorption. Those are real "bass traps".


> With this layout I could do 6" for anything exposed on the walls, but behind the screen go more like 10"+ and the rear wall corners could go thicker as well.


The thicker the absorber panel, the less dense the absorption material needs to be to remain effective. After a certain thickness, the denser material prevents sound from traveling through, so it ends up reflecting more than absorbing. IF you're going to do something like 8"-12" of absorption, better to switch to the lighter OC701. If you're going to go thicker (2'-4'), switch to something even less dense, like the cheap pink fluffy stuff.


> Can I over-deaden the room?


Of course you can. But that's not going to happen with most of the absorption on the front wall and half the back wall. Our human hearing gets its sense of spaciousness from lateral (sideways moving) sound. There should be no shortage of that in your room. That's the opposite of a dead room.


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## anjunadeep

sdurani said:


> Yes, for broadband absorption of reflections from your speakers. To absorb deep bass from your subs, you'll need 3'-4' feet of absorption. Those are real "bass traps". The thicker the absorber panel, the less dense the absorption material needs to be to remain effective. After a certain thickness, the denser material prevents sound from traveling through, so it ends up reflecting more than absorbing. IF you're going to do something like 8"-12" of absorption, better to switch to the lighter OC701. If you're going to go thicker (2'-4'), switch to something even less dense, like the cheap pink fluffy stuff. Of course you can. But that's not going to happen with most of the absorption on the front wall and half the back wall. Our human hearing gets its sense of spaciousness from lateral (sideways moving) sound. There should be no shortage of that in your room. That's the opposite of a dead room.


Thank you. For making the room sound bigger than it is, will the close sidewalls be a problem? That drawing of the recliners isn't really accurate, I just wanted to show a general idea where they are but I'll probably pick seating that keeps listeners on the spaced from the wall as much as possible. Someone also told me maybe I could put the surrounds a bit further back and aim them directly at the opposite side and vice versa so the side seats are a bit off axis from the surround close to them.


----------



## sdurani

anjunadeep said:


> For making the room sound bigger than it is, will the close sidewalls be a problem?


Nope. Think of your side walls as acoustic mirrors. If your L/R speakers are 2' in from the side walls, then their 1st reflections are going to create virtual L/R speakers 2' on the other side of the wall. The reflections won't be delayed enough and loud enough to be heard as a separate sound (echo). But they will cause the image to move outward, towards the virtual L/R speakers, creating a soundstage with phantom imaging that sometimes appears to be wider than the room. IF you end up not liking that effect, just absorb those reflections and your soundstage will shrink to the width of your L/R speakers.


> Someone also told me maybe I could put the surrounds a bit further back and aim them directly at the opposite side and vice versa so the side seats are a bit off axis from the surround close to them.


It's an old trick called time-energy trading. Speakers tend to sound louder on-axis (aimed at you). Speakers also sound louder when they are closer to you. You can use one of those to compensate for the other by aiming each speaker at the listener farthest away. This lowers the level of the speaker closest to you (cuz you're hearing it off-axis) and boosts the level of speaker farthest from you (cuz it's pointed at your ears). Really helps reduce the disparity between near and far speakers for any listener not sitting in the sweet spot. I would do that for every speaker group (Fronts, Wides, Sides, Rears and all 4 Heights). 

BTW, I would not put the Side speakers rearward of the listeners. You already have a pair of speakers (Rears) back there, so it would be a waste of resources to have ALL 4 surrounds behind the listeners. Placing the Sides slightly forward of the listeners will aid in spaciousness and give you greater side-vs-rear separation in the surround field.


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## fattire

What are folks doing for rattling cabinet doors? I've got a media console and some storage cabinets that can drive me nuts depending on the content we're watching or listening to.

I was thinking of just using some MLV on the insides of the doors. Thoughts on this approach? Better suggestions? If it's the right way to go, any specific MLV that y'all would recommend? I'd like to avoid fumes if possible (some of the old stuff I used in cars back in the day stunk like hell; not something I want in the house if I can avoid it).


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## nathan_h

If it's the doors rattling against the cabinet they are attached to, I have found that felt strips (sort of like weather stripping but more light weight) or small rubber knobs (like you use on the back of a picture frame to prevent it from scratching the wall) can work well.


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## fattire

nathan_h said:


> If it's the doors rattling against the cabinet they are attached to, I have found that felt strips (sort of like weather stripping but more light weight) or small rubber knobs (like you use on the back of a picture frame to prevent it from scratching the wall) can work well.


That might work for some of them; I'll need to double-check the mechanisms to be sure. The two most offensive use small magnetic latches that have a bit of play in them. They're similar to these JQK Magnetic Cabinet Door Catch, Stainless Steel Closet Catches with Strong Magnetic, 1.2mm Thickness Furniture Latch 20 lbs Oil Rubbed Bronze (Pack of 4), CC101-ORB-P4 - - Amazon.com. Felt would keep them from securing closed I think. The magnets aren't really very powerful.


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## anjunadeep

sdurani said:


> Nope. Think of your side walls as acoustic mirrors. If your L/R speakers are 2' in from the side walls, then their 1st reflections are going to create virtual L/R speakers 2' on the other side of the wall. The reflections won't be delayed enough and loud enough to be heard as a separate sound (echo). But they will cause the image to move outward, towards the virtual L/R speakers, creating a soundstage with phantom imaging that sometimes appears to be wider than the room. IF you end up not liking that effect, just absorb those reflections and your soundstage will shrink to the width of your L/R speakers. It's an old trick called time-energy trading. Speakers tend to sound louder on-axis (aimed at you). Speakers also sound louder when they are closer to you. You can use one of those to compensate for the other by aiming each speaker at the listener farthest away. This lowers the level of the speaker closest to you (cuz you're hearing it off-axis) and boosts the level of speaker farthest from you (cuz it's pointed at your ears). Really helps reduce the disparity between near and far speakers for any listener not sitting in the sweet spot. I would do that for every speaker group (Fronts, Wides, Sides, Rears and all 4 Heights).
> 
> BTW, I would not put the Side speakers rearward of the listeners. You already have a pair of speakers (Rears) back there, so it would be a waste of resources to have ALL 4 surrounds behind the listeners. Placing the Sides slightly forward of the listeners will aid in spaciousness and give you greater side-vs-rear separation in the surround field.


Love these ideas, thank you.

Yeah, I mean one thing I'd like to look into is paneling the walls in some way where I can adjust speakers and acoustic treatments without effecting the rooms decor much. I was curious about maybe using magnets or something to accomplish that. Maybe not possible in a thin room like this. I am in the planning stage and may be able to steal some inches here or there though.


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## Pretorian

ajax-jp said:


> Been a little busy, but I figured I'd post some pictures of the room after I got all of the treatments up.
> I took a lot of measurements along the way and lost a few of them....
> All in all, I installed 10 panels, 2 on the back wall, 2 tri-traps stacked in each corner and 2 on each side wall.
> 
> To sum up the difference, it was jarring.
> Quiet vocals in movies completely cleared up. This was probably my biggest complaint going in, that vocals, especially at low volumes, were muddy and hard to understand.
> 
> Loud listening is no longer fatiguing. (I had always just thought I had it too loud).
> 
> There is much less sound hanging in the room. This was immediately noticeable when I added the treatments at the early reflection points (treatments came in in multiple shipments and went on the walls in this order: back, left+right, lower corners, upper corners) Instruments now stop and start quickly and cleanly. You can hear the gaps instead of notes hanging in the room filling them. Imaging improved because of this providing much more 3 dimensional sound on stereo listening. Soundstage is noticeably wider and very open sounding.
> 
> LFE cleaned up quite a bit, and I was actually able to turn DOWN all of the amps and get the same level of output or better. I had a null down at 47hz that is completely gone. I still have a null at 66hz but it's ~6db, nowhere near as bad as the 15db loss I had at 47hz. It might be something I can work out w/the mini-dsp or just adjusting the positions of the subs (I only have 1 in the rear because I have nowhere to put a second one).
> 
> Overall, the room is noticeably quieter, and a ton cleaner. And best of all, my wife can tell the difference, so I'm not totally losing my mind.
> 
> View attachment 3164267
> 
> View attachment 3164266


Wow, that is a great story. Congrats. Sounds like my Acoustic install I did a few months ago. I ordered from GIK. I have what you have but only one BASS panel at the back wall and I have two panels in the ceiling.
I love how quiet the room is just stepping inside. It feels so much more "cinema".


----------



## ajax-jp

Pretorian said:


> Wow, that is a great story. Congrats. Sounds like my Acoustic install I did a few months ago. I ordered from GIK. I have what you have but only one BASS panel at the back wall and I have two panels in the ceiling.
> I love how quiet the room is just stepping inside. It feels so much more "cinema".


Totally worth it and agreed, the room is incredibly quiet. Only reason I haven't mounted any panels on the ceiling is that it's sloped and hanging panels didn't have acceptable levels of wife acceptance factor. I'm looking at just getting 6-8 vicoustic cinema rounds and glueing them up, but we'll see. She wants me to do a star ceiling.. and while I admit, they're awesome, I'd rather spend that money on gear... not that I need any more gear, lol.

The worst thing about acoustic treatments is it allows you to hear the other inconsistencies.. I've probably moved my front left / right speakers 5+ times since I put the panels up and recalibrated the room about double that.
I was able to fix the remaining issues I mentioned above with just speaker positions and a very minor delay to the rear sub with the mini-dsp (2ms).


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## niterida

ajax-jp said:


> She wants me to do a star ceiling.. and while I admit, they're awesome, I'd rather spend that money on gear... not that I need any more gear, lol.


I made up my own acoustic panels for the ceiling and wrapped them in galaxy print material. This one here from Kmart at $14AUD :










I used the dark side for 2 reasons
1. It looked better
2. I have a Star Wars themed room 

I haven't actually finished them yet but here is a pic of the panels with different print and one of my side wall panels with the new print just draped over it :


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## dengland

In my HT, I ended up with the side of an equipment rack approximately at a 1st reflection point. (Left Front speaker is 3' from left wall and Right Front speaker is about 5.5' off of the right wall.) The side of the 7' tall EQ rack ends up about 3' from the right speaker.

If I have a max of 4" to treat the side of the EQ rack due to walkway, would absorption or diffusion be better for the side of the rack?

Thanks


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## nathan_h

Probably absorption though maybe with slats to prevent too much high frequency energy from being attenuated


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## rec head

Sorry. This has probably been covered many times but I'm in information overload right now. 

In general is it better to use 6" thick absorbers or 3" thick absorbers spaced 3" off the ceiling?


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## nathan_h

Oversimplifying:

The 6" one will trap a bit more QUANTITY, but if it is a hardship, 3" spaced 3" off the ceiling does a fine job of trapping the same frequencies but with less quantity.


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## rec head

Quantity being less overall reduction?


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## nathan_h

Right. The gap makes the frequency range impacted similar to a thicker panel, but the amount of overall reduction is a little less.


----------



## Senimark

Can anyone help with Gik panels?
I have a few questions.
Are the black fabrics non reflective?
Or can I cover them with black velvet and still get the same result?


----------



## niterida

rec head said:


> Sorry. This has probably been covered many times but I'm in information overload right now.
> 
> In general is it better to use 6" thick absorbers or 3" thick absorbers spaced 3" off the ceiling?


Depends on what frequencies you are trying to absorb. Seethe following 3 graphs. Blue line in each is 3" with 3" air gap, compared to 3" no air gap, 6" no air gap and 6" with 6" air gap. Gnerally any given thickness will work better if it is mounted that same thickness away from the wall/ceiling.
You can find the calculator here : Porous Absorber Calculator


----------



## nathan_h

Senimark said:


> Can anyone help with Gik panels?
> I have a few questions.
> Are the black fabrics non reflective?
> Or can I cover them with black velvet and still get the same result?


They have different fabric options. I paid for them to upgrade me to GOF fabric and it is non reflective. I don't know if their standard fabric is non reflective, but they will send you a swatch for free so you can check it out for yourself.

I think covering the panel is something like velvet is likely to change the acoustic absorption properties. Notice I said CHANGE and not necessarily HARM. It would likely reduce the amount of high frequency absorption, but still do fine with longer wavelengths, which might be what some people want.


----------



## ajax-jp

Senimark said:


> Can anyone help with Gik panels?
> I have a few questions.
> Are the black fabrics non reflective?
> Or can I cover them with black velvet and still get the same result?





nathan_h said:


> They have different fabric options. I paid for them to upgrade me to GOF fabric and it is non reflective. I don't know if their standard fabric is non reflective, but they will send you a swatch for free so you can check it out for yourself.


The standard black fabric is also non-reflective.


----------



## rec head

niterida said:


> Depends on what frequencies you are trying to absorb. Seethe following 3 graphs. Blue line in each is 3" with 3" air gap, compared to 3" no air gap, 6" no air gap and 6" with 6" air gap. Gnerally any given thickness will work better if it is mounted that same thickness away from the wall/ceiling.
> You can find the calculator here : Porous Absorber Calculator
> View attachment 3170482
> View attachment 3170483
> View attachment 3170484


Thanks. I'm having a hard time determining the Flow resistivity rating for Roxul Safe and Sound. You used 2,000 the default in the calculator is 10,000.


----------



## niterida

rec head said:


> Thanks. I'm having a hard time determining the Flow resistivity rating for Roxul Safe and Sound. You used 2,000 the default in the calculator is 10,000.


Yeah I just used 2000 as most of the 3" thick fluffy will be at least that much - but I posted just to show the differences between the thickness and mounting options.
Look here : https://www.bobgolds.com/AbsorptionCoefficients.htm


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## Pretorian

Senimark said:


> Can anyone help with Gik panels?
> I have a few questions.
> Are the black fabrics non reflective?
> Or can I cover them with black velvet and still get the same result?


I have regular black GIK panels. For me they keep the reflections to a minimum.


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## rec head

niterida said:


> Yeah I just used 2000 as most of the 3" thick fluffy will be at least that much - but I posted just to show the differences between the thickness and mounting options.
> Look here : https://www.bobgolds.com/AbsorptionCoefficients.htm


I appreciate the help. I've done a lot of reading and watched many videos. Now that I'm actually planning out and building panels I feel like I forgot everything. More questions to follow for sure.


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## matt-sf

Does anyone have advice on how to color-match acoustic panels to painted drywall?

I'm going to be treating my home theater with 2-4" thick panels - likely some combination of Roxul Rockboard 40 and / or FabricMate ReCore.

I'm hoping to have the treatments match the wall, which are painted a soft black (Farrow & Ball Railings). The walls have a blue undertone so stock black fabrics don't match.

Any ideas of how to achieve this? 

The manufacturers of FabricMate suggest painting their panels with non-bridgable paint, aka acoustic paint. I've found a few products such as SonoKote and Kelly-Moore ceiling paint. Any experience or opinions with this solution?

I've also considering getting acoustic fabric with a custom color, but I haven't been able to find a vendor. GoM normally would do this but they are production limited right now. Any ideas for where I could source this?

Thanks in advance!


----------



## rec head

I'm going thought the color matching myself. GoM will send you swatches. Mine came really fast. That is the first I have heard of those paints and I would also like to know if anyone has used/tested it.


----------



## Anton Rönnkvist

I am building a cinema room in the basement and have a wc pipe leading up to the upper floor. I have filled with insulation and thought to put a plasterboard over but came to think that it might work as a bass trap. It is not that deep, only 25cm maybe. Is it a stupid idea or should I just put a plasterboard over. The room is 650x350x220cm


----------



## fattire

Anton Rönnkvist said:


> View attachment 3171397
> View attachment 3171397
> I am building a cinema room in the basement and have a wc pipe leading up to the upper floor. I have filled with insulation and thought to put a plasterboard over but came to think that it might work as a bass trap. It is not that deep, only 25cm maybe. Is it a stupid idea or should I just put a plasterboard over. The room is 650x350x220cm


25 cm is pretty good but the placement is tough. Closer to, or in, the corner would be best. If building it out to the corner is an option it could work quite well.


----------



## nathan_h

matt-sf said:


> Does anyone have advice on how to color-match acoustic panels to painted drywall?
> 
> I'm going to be treating my home theater with 2-4" thick panels - likely some combination of Roxul Rockboard 40 and / or FabricMate ReCore.
> 
> I'm hoping to have the treatments match the wall, which are painted a soft black (Farrow & Ball Railings). The walls have a blue undertone so stock black fabrics don't match.
> 
> Any ideas of how to achieve this?
> 
> The manufacturers of FabricMate suggest painting their panels with non-bridgable paint, aka acoustic paint. I've found a few products such as SonoKote and Kelly-Moore ceiling paint. Any experience or opinions with this solution?
> 
> I've also considering getting acoustic fabric with a custom color, but I haven't been able to find a vendor. GoM normally would do this but they are production limited right now. Any ideas for where I could source this?
> 
> Thanks in advance!


These may not be the panels you want but this vendor explicitly does color matching with Sherwin Williams.









AcoustiColor® Acoustic Panels


Orders of $2,500 or more may require longer lead times. Please contact us if there are any questions. Customizable




www.audimute.com


----------



## matt-sf

nathan_h said:


> These may not be the panels you want but this vendor explicitly does color matching with Sherwin Williams.


Thank you! That's perfect. I'm planning to do 3-4" of panel depth; I can easily add a standard 2" panel in back of the AccoustiColor.


----------



## RVD26

Pretorian said:


> I have regular black GIK panels. For me they keep the reflections to a minimum.
> View attachment 3170607


The only reflective part of the panels are the logo stickers they put on there.


----------



## Pretorian

RVD26 said:


> The only reflective part of the panels are the logo stickers they put on there.


And they fell off when I started Tenet on reference level.


----------



## fracchia23

Hi guys I'm from Italy, I have the rp-280fa and above the surrounds the upfiring atmos speaker, I would treat the roof but I don t find nothing about how to with upfiring.Do you all know if I should go with diffusers on the first reflection points or should I leave the 2,70mt high without treatment?


----------



## nathan_h

I would probably not treat the ceiling if I was using up firing Atmos speaker modules.


----------



## IMostlyPreferOLED

nathan_h said:


> I would probably not treat the ceiling if I was using up firing Atmos speaker modules.


GIK recommended against it treating ceiling, unless very carefully done. When my barber tells me I don’t need a haircut, I listen


----------



## fracchia23

IMostlyPreferOLED said:


> GIK recommended against it treating ceiling, unless very carefully done. When my barber tells me I don’t need a haircut, I listen


I'm so sorry but I don't understood what you said.Please can you answer me in an easy way.
Ty


----------



## fattire

fracchia23 said:


> Hi guys I'm from Italy, I have the rp-280fa and above the surrounds the upfiring atmos speaker, I would treat the roof but I don t find nothing about how to with upfiring.Do you all know if I should go with diffusers on the first reflection points or should I leave the 2,70mt high without treatment?


I agree with the other responses. Atmos Enabled speakers require reflection off the ceiling to function properly. It’s how they are designed.

If you were to treat the ceiling, then you would effectively eliminate their effect.

EDIT: you can still treat the front wall as usual (as much coverage with 4”-6” thick absorption as possible) which should improve things.


----------



## nathan_h

And often treating the rear wall a lot can help too.


----------



## nathan_h

fracchia23 said:


> I'm so sorry but I don't understood what you said.Please can you answer me in an easy way.
> Ty


He means: Do not put acoustic treatment on the ceiling when you are using ATMOS speakers that reflect sound off the ceiling.


----------



## IMostlyPreferOLED

nathan_h said:


> He means: Do not put acoustic treatment on the ceiling when you are using ATMOS speakers that reflect sound off the ceiling.


Yes, fracchia23, my apologies for not remembering that English sayings are not easy for you to understand. What Nathan said is correct. My joke was a play on the fact that a barber, who makes a living from cutting hair, should be believed if he says your hair does not need cutting. So, if a GIK salesman tells me to not put their panels on the ceiling, I should believe him because he sells panels for a living.


----------



## fracchia23

Ty so much guys.I hace small room,on the right has windows, on the left is open to the kitchen, my sofa is 10cm far from the rear wall.Im thinking to but heavy curtains to cover all the windows from the roof to the floor,build an acoustic panel for the rear wall and 3 acoustic panels for the front wall placing them behind the towers and the 65 inches tv.
What do you think about this?


----------



## nathan_h

That sounds like a good plan. The panels behind you will be the most important in that room. Can you share a photo?


----------



## fracchia23

nathan_h said:


> That sounds like a good plan. The panels behind you will be the most important in that room. Can you share a photo?


Hi everybody this is my living room, the front speakers are now behind the tv due to my little doughter that loves to go behind touching everything and is missing the left surround and atmos due to the same reason...My doughter


----------



## nathan_h

Yes I suspect panels in these locations will help, especially behind the couch.











And then the front wall as much as the family will tolerate, starting with the area behind the tv, will probably help too. But the most important thing is behind the couch.


----------



## fracchia23

nathan_h said:


> Yes I suspect panels in these locations will help, especially behind the couch.
> 
> View attachment 3173213
> 
> 
> 
> And then the front wall as much as the family will tolerate, starting with the area behind the tv, will probably help too. But the most important thing is behind the couch.
> 
> View attachment 3173215


You know whay? On the right side,the windows side especially on the big windows and exactly where is placed the right surround the sound is so so so Boomy but literally boomy ,I mean on the left side I have close to no bass instead on the right seams to be at the discotheque in the 90'


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## nathan_h

Hard to say. Do you have a subwoofer? 

And what kind of AVR do you use? For example, Denon? Yamaha? Etc. 

My guess would be that equalization or setup (of the subwoofer) may help.


----------



## fracchia23

nathan_h said:


> Hard to say. Do you have a subwoofer?
> 
> And what kind of AVR do you use? For example, Denon? Yamaha? Etc.
> 
> My guess would be that equalization or setup (of the subwoofer) may help.


Denon x6200w 
Subwoofer Klipsch r-115sw 
I used the phonometer to set all the speakers at 75db ..


----------



## nathan_h

Okay, that’s a good AVR.

If you use the automatic setup procedure (Audyssey) with the included microphone, you should get fine results. 

Note : when using the microphone, measure several times all just with the two main seat locations on the couch.

You do not need to manually adjust anything to be 75db.

Set your speakers to ”small”.

Therr may still be some ”boom” in the corner. That is normal when using a single subwoofer in a room. It cannot be avoided. The goal is to make your main seat sound good, and not worry about the corner.

There is a whole different topic about Audyssey that would be a good place to ask more questions.

And I can recommend you listen to this podcast if spoken English is comfortable: Podcast Archives | AV Rant

You can send them an email and they will answer questions you have as well.


----------



## fracchia23

Omg ty so much.However audissey makes me measure the main search and also the right and left spot too . I already did everything u said but the boomy sound still, for this reason I want to build the 10cm deep acoustic panels .


----------



## DMILANI

Hi all,

I am upgrading my home theater with a new AT scope screen (120" wide, most likely Dreamscreen V7 material). I am also putting in 3 Triad Bronze/4 In-wall LCRs directly behind the screen. From reading this thread and others, the consensus is to put Linacoustic material behind the screen itself to tame reflections from both the back of the screen material as well as from the surrounds.

If this is true, do I install the Linacoustic mat right up to the Triad speakers? My understanding is that in-walls are designed assuming a hard surface surround them, so not sure if I need to leave some gap around the speakers themselves, or simply go right up to their frames. Also, I found some 1/2" Linacoustic material online, can I simply put up multiple layers to get the preferred 2" thick? And can the Linacoustic be exposed directly to the backside of the screen, or do I need to add a layer of GoF fabric (or similar) to contain the fibers? I think the Linacoustic already has a "crusty" out layer to keep fibers at bay.

Finally, how much space do I need between the speaker drivers and the back of the V7 material? It's a woven material, so should be about to get close, but not sure if 2" is too close assuming I use 2" worth of furring strips to accommodate the Linacoustic material.

Thanks,
Dino


----------



## fracchia23

Another question: I want to build 4 inch thick acoustic panels and place them on the walls where we talking about but the question now is... what kind of rockwool?density? Etc...


----------



## squared80

fracchia23 said:


> Another question: I want to build 4 inch thick acoustic panels and place them on the walls where we talking about but the question now is... what kind of rockwool?density? Etc...


Rockwool 60.


----------



## corock

I just finished applying acoustical treatment to my HT. The diffusion acoustic panels, corner foam, and subwoofer top foam are from UA Acoustics, and the art panels are from GIK. It's not the most high end panels available, but this did allow me to apply treatment within my budget and I like the aesthetic.


----------



## rec head

We workout in our "theater" too so I call mine a TV room. Yours has much more of a theater vibe and looks great.


----------



## fracchia23

What do you think about *ROCKWOOL 225 ACOUSTIC PLUS*


----------



## squared80

fracchia23 said:


> What do you think about *ROCKWOOL 225 ACOUSTIC PLUS*


Don't know anything about it, but if you have unlimited finds, get whatever you want. Diminishing returns at some point, though. Rockwool 60 is cost effective and gets the job done.

If questions, try this...


http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## corock

rec head said:


> We workout in our "theater" too so I call mine a TV room. Yours has much more of a theater vibe and looks great.


You could say I have a theater that I happen to work out in, OR that I have a gym with one hell of a sound system!


----------



## DMILANI

DMILANI said:


> Hi all,
> 
> I am upgrading my home theater with a new AT scope screen (120" wide, most likely Dreamscreen V7 material). I am also putting in 3 Triad Bronze/4 In-wall LCRs directly behind the screen. From reading this thread and others, the consensus is to put Linacoustic material behind the screen itself to tame reflections from both the back of the screen material as well as from the surrounds.
> 
> If this is true, do I install the Linacoustic mat right up to the Triad speakers? My understanding is that in-walls are designed assuming a hard surface surround them, so not sure if I need to leave some gap around the speakers themselves, or simply go right up to their frames. Also, I found some 1/2" Linacoustic material online, can I simply put up multiple layers to get the preferred 2" thick? And can the Linacoustic be exposed directly to the backside of the screen, or do I need to add a layer of GoF fabric (or similar) to contain the fibers? I think the Linacoustic already has a "crusty" out layer to keep fibers at bay.
> 
> Finally, how much space do I need between the speaker drivers and the back of the V7 material? It's a woven material, so should be about to get close, but not sure if 2" is too close assuming I use 2" worth of furring strips to accommodate the Linacoustic material.
> 
> Thanks,
> Dino


Would really appreciate some feedback on my questions. Thanks in advance.


----------



## Sam Ash

DMILANI said:


> Hi all,
> 
> I am upgrading my home theater with a new AT scope screen (120" wide, most likely Dreamscreen V7 material). I am also putting in 3 Triad Bronze/4 In-wall LCRs directly behind the screen. From reading this thread and others, the consensus is to put Linacoustic material behind the screen itself to tame reflections from both the back of the screen material as well as from the surrounds.
> 
> If this is true, do I install the Linacoustic mat right up to the Triad speakers? My understanding is that in-walls are designed assuming a hard surface surround them, so not sure if I need to leave some gap around the speakers themselves, or simply go right up to their frames. Also, I found some 1/2" Linacoustic material online, can I simply put up multiple layers to get the preferred 2" thick? And can the Linacoustic be exposed directly to the backside of the screen, or do I need to add a layer of GoF fabric (or similar) to contain the fibers? I think the Linacoustic already has a "crusty" out layer to keep fibers at bay.
> 
> Finally, how much space do I need between the speaker drivers and the back of the V7 material? It's a woven material, so should be about to get close, but not sure if 2" is too close assuming I use 2" worth of furring strips to accommodate the Linacoustic material.
> 
> Thanks,
> Dino


Your acoustic material can come right up to the frame of the Triad speakers and yes, the speaker being 2" away from the screen is fine.


----------



## DMILANI

Thanks Sam!


----------



## hemiutut

corock said:


> I just finished applying acoustical treatment to my HT. The diffusion acoustic panels, corner foam, and subwoofer top foam are from UA Acoustics, and the art panels are from GIK. It's not the most high end panels available, but this did allow me to apply treatment within my budget and I like the aesthetic.
> 
> View attachment 3176566
> 
> 
> View attachment 3176567
> 
> 
> View attachment 3176568


Do you have measurements of the room with the acoustic treatment?
It's just curious to see what TR (T20, T30, Topt) has, Waterfall, etc, etc.

Written with translator.

Greetings


----------



## corock

hemiutut said:


> Do you have measurements of the room with the acoustic treatment?
> It's just curious to see what TR (T20, T30, Topt) has, Waterfall, etc, etc.
> 
> Written with translator.
> 
> Greetings
> [/QUOT


Not yet. I haven't had time to rerun Audyssey since I finished the treatment.


----------



## DarinS

So, I have some left over Roxul and Linacoustic following construction of my theater. Which is better to make some absorption panels with? I'm guessing the Roxul but wanted to make sure. The Roxul was used in my walls and the linacoustic 1" as a double layer with 6mil plastic between them and about 3/4" air gap at the front wall behind the AT screen. Thanks.


----------



## hemiutut

corock said:


> Not yet. I haven't had time to rerun Audyssey since I finished the treatment.


With Audyssey you won't be able to see the acoustics of the room, if you can make measurements with the Room EQ Wizard, with the Audyssey mic for starters there is plenty.
My recommendation is that I tried the low frequencies as much as possible.
Rest assured that it will not be overstated, although a priori it may seem that it puts a lot of treatment for these frequencies.

Having a dedicated room makes it very easy.

I hope you understand what I say.
Written with Google translate

Greetings


----------



## corock

hemiutut said:


> With Audyssey you won't be able to see the acoustics of the room, if you can make measurements with the Room EQ Wizard, with the Audyssey mic for starters there is plenty.
> My recommendation is that I tried the low frequencies as much as possible.
> Rest assured that it will not be overstated, although a priori it may seem that it puts a lot of treatment for these frequencies.
> 
> Having a dedicated room makes it very easy.
> 
> I hope you understand what I say.
> Written with Google translate
> 
> Greetings


Yes, I understand. I have all the equipment to take measurements with REW, but I won't do that until after I've run Audyssey room equalization.


----------



## dwander

I’m going to make some inelegant bass traps out of 703. On the rear wall the door is centered and to the left and right there are false walls open to 24x48 areas that house rear channels and big DIY subs. So I want to treat the two corners of each of those areas (4 corners total). I was just going to cut the 2” 703 boards in half length wise and attach a bunch together and run them up to the ceiling. From the top of subwoofer to the ceiling is just under 48”. 

With two 6 packs of 2” 703 I can put together 4 12”x12” traps. I’d like to effectively treat below 60 hz though, and I am not sure how to use the spec sheet to calculate the effectiveness of 12” 703 on the lower frequencies.


----------



## nathan_h

Assuming there is something to hold it in place, you don’t need to spend for 703. Just buy rolls of pink fluffy stuff and pile it until the whole cavity is filled. That will give you what, two to four feet of depth? That’s very broad band. 

If that impacts high frequencies too much you can put up some scatter plate type covering in front of it.


----------



## dwander

nathan_h said:


> Assuming there is something to hold it in place, you don’t need to spend for 703. Just buy rolls of pink fluffy stuff and pile it until the whole cavity is filled. That will give you what, two to four feet of depth? That’s very broad band.
> 
> If that impacts high frequencies too much you can put up some scatter plate type covering in front of it.


I considered that doing that. Just figured this would be easier. I would have to build boxes out of wood, and probably then wrap in a fabric. With the rigid boards, I figured I could just bundle together and throw them up.


----------



## hemiutut

Can you put the resistivity values to the passage of air in
kPa ∙ s / m2 or extrapolated to European measurements?

Written with translator.

Greetings


----------



## nathan_h

dwander said:


> I considered that doing that. Just figured this would be easier. I would have to build boxes out of wood, and probably then wrap in a fabric. With the rigid boards, I figured I could just bundle together and throw them up.


I can't quite picture the situation, so my opinion on relative ease versus cost versus effectiveness would be a wild guess and depend a bit on whether budget is a factor. 

I can relatively safely assert that more bulk is better and it sounds like you have a large space available so I would max it out, regardless of what materials you use, all other things being equal.

So yes piles of rigid boards would be great. Lots of it, very thick and deep and tall and wide is probably a good way to go.


----------



## dwander

nathan_h said:


> I can't quite picture the situation, so my opinion on relative ease versus cost versus effectiveness would be a wild guess and depend a bit on whether budget is a factor.
> 
> I can relatively safely assert that more bulk is better and it sounds like you have a large space available so I would max it out, regardless of what materials you use, all other things being equal.
> 
> So yes piles of rigid boards would be great. Lots of it, very thick and deep and tall and wide is probably a good way to go.


Ok, thanks. So I’ll beef it up then. I’ll go for 18” depth definitely and see if I can also get the width close to that.


----------



## IMostlyPreferOLED

While waiting for my GIK bass traps, I stuffed GIK’s product (Knauf Insulation Earthwool® Insulation Board with ECOSE® Technology 3lb) into a smaller space (roughly 4’x2’x2’). It made enough of a difference that I’m really looking forward to the bass traps.


----------



## AndreNewman

I'm considering covering my ceiling with some sort of acoustic treatment probably some Knauf Earthwool board in a frame with fabric stretched over, I've built lots of other panels. I'd like to use 25mm (1") so I don't lower the ceiling significantly, it's 2.54m but I'd like to keep some height. I have 100mm 4" panels elsewhere in the room also 300mm and 500mm square bass traps in the corners. The ceiling is the only remaining completely untreated surface.

I get that the thicker it is the lower frequencies get absorbed but I can't really work out if 25mm or 50mm would be sufficient. I have REW Impulse measurements where the ceiling spike is visible, does that help identify how much is enough?

It's a big area 5.4m x 4.4m so I don't want to do 25mm and then go "nah need to do it again"!

Any advice, any experience?


----------



## hemiutut

My group of friends here in Spain use Knauf of 5000 kPa ∙ s / m2, for absorbent porous panels 25 cm thick and up and for the most serious frequencies, Dacron (wadding is called in Spain) for panels from 40- 50-60 cms thick or more is the best that goes.



















Written with translator

Greetings


----------



## squared80

AndreNewman said:


> Any advice, any experience?


Anything less than 4" is pointless.


----------



## BIGmouthinDC

squared80 said:


> Anything less than 4" is pointless.


Utter internet urban legend nonsense.


----------



## squared80

BIGmouthinDC said:


> Utter internet urban legend nonsense.


That's what all these highly recommended websites and audio experts say. So that's all nonsense? 2" in my corners will be as effective as 4"?


----------



## nathan_h

Effective versus pointless is not equivalent. 2" will make an impact. It won't do as well for broadband absorption (ie, go as low as well) and often broadband absorption is preferable when possible so that you don't attenuate the high frequencies without impacting the lower ones. There are ways to mitigate the possible issues with thiner panels such as some scatter plates to reduce their high frequency attenuation.

In corners, if you straddle the corner, you get deeper frequency response control but not as substantial an amount of absorption as a thicker panel will provide in the corner.


----------



## BIGmouthinDC

The best room I ever heard was an old one designed by Dennis Erskine and it only had one inch of treatment on some portions of the wall, it was old school. Quest acoustical interiors run by Gerry Lamay sells various treatments that are all 2 inches except his 4 inch bass absorbers, He teaches the international room setup and design classes for room calibrators. Home Acoustics Alliance Portal | Home Theater Designers.

don't believe everything "experts" say on the internet.

Square80 Your statement that anything less than 4 inches is pointess was in resonse to a guy who wanted to cover his entire ceiling, this is basically bad advice.


----------



## squared80

BIGmouthinDC said:


> Square80 Your statement that anything less than 4 inches is pointess was in resonse to a guy who wanted to cover his entire ceiling, this is basically bad advice.


I was under the impression he was talking about bass in his corners, not covering his ceiling. Other than those places and behind my sound stage, I'll be using 2". But that's not for bass mgmt.


----------



## hemiutut

I recommend this engineer's channel.
Short videos and explained very well.











Greetings


----------



## AndreNewman

squared80 said:


> I was under the impression he was talking about bass in his corners, not covering his ceiling. Other than those places and behind my sound stage, I'll be using 2". But that's not for bass mgmt.


Nope, corners are done, bass is fine although a third and fourth subwoofer would be nice, I thought I explained in the original post.

I have 300mm and 500mm bass traps in all 4 vertical corners, also 2 horizontal corners around the screen. All that can be done due to doors and windows etc, works really well.
I have heavy velvet curtains with acoustic backing all around the room, can't really do panels due to doors windows and a desire to draw back the curtains and have a semi normal living room when the projector isn't on. The curtains work far better than I expected, happy there.

Dirac picks up the rest.

I am considering what to do with my untreated ceiling, it needs overboarding at the very least but I'd like to gain some acoustic benefit for the expense and hassle. I'm considering a fabric ceiling (over the whole 4.4m x 5.4m ceiling) such that I can put some acoustic material behind. 

Hence the is 1" going to be pointless question.

1" would be easy, 
2" might be ok, 
4" I need to have a serious think about that but it would be easier to hide some atmos speakers inside.

I'm assuming that whatever thickness is beneficial I probably want denser board rather than loose fluffy insulation to reduce the chance of sagging and make installation easier.

I've seen perforated plasterboard used as a diffuser in meeting rooms and corridors, that's another option but my wife doesn't like the look and I'd rather have absorption than diffusion.


----------



## AndreNewman

BIGmouthinDC said:


> The best room I ever heard was an old one designed by Dennis Erskine and it only had one inch of treatment on some portions of the wall, it was old school. Quest acoustical interiors run by Gerry Lamay sells various treatments that are all 2 inches except his 4 inch bass absorbers, He teaches the international room setup and design classes for room calibrators. Home Acoustics Alliance Portal | Home Theater Designers.
> 
> don't believe everything "experts" say on the internet.
> 
> Square80 Your statement that anything less than 4 inches is pointess was in resonse to a guy who wanted to cover his entire ceiling, this is basically bad advice.


So what's the good advice?

Thanks


----------



## BIGmouthinDC

AndreNewman said:


> I'm considering covering my ceiling with some sort of acoustic treatment probably some Knauf Earthwool board in a frame with fabric stretched over, I've built lots of other panels. I'd like to use 25mm (1") so I don't lower the ceiling significantly, it's 2.54m but I'd like to keep some height. I have 100mm 4" panels elsewhere in the room also 300mm and 500mm square bass traps in the corners. The ceiling is the only remaining completely untreated surface.
> 
> I get that the thicker it is the lower frequencies get absorbed but I can't really work out if 25mm or 50mm would be sufficient. I have REW Impulse measurements where the ceiling spike is visible, does that help identify how much is enough?
> 
> It's a big area 5.4m x 4.4m so I don't want to do 25mm and then go "nah need to do it again"!
> 
> Any advice, any experience?





AndreNewman said:


> So what's the good advice?
> 
> Thanks


if it is a spike probably better room calibration (EQ). Also need to know what frequency is the spike. We don't know if it is a floor ceiling resonance or a first reflection issue. knowing the timing delay of the spike would also be useful. We also know nothing of the design or the room, position of the measurement, single or an average of all listening positions. Maybe diffusion instead of absorption would work. Just too many unknowns. I don't know enough on the topic to fix your problem but I know enough to recognize when a shotgun solution may not be the overall best strategy. Treating the entire ceiling with 4 inches will suck a lot of energy out of your soundtrack.


----------



## Mihadis

I am making rough sketches for a second row riser which would double as a bass trap. Since there will be leftover space behind the 2nd row, I was thinking the riser/bass trap could be made even taller (see attached image) and become more effective. Does that make sense? Or would I make it worse somehow? I haven't seen anyone do this. And where would you put the vents in this case?

Thanks in advance!


----------



## AndreNewman

Thanks for the reply.



BIGmouthinDC said:


> if it is a spike probably better room calibration (EQ).


Dirac did reduce it's effect considerably, probably in terms of first reflection from LCR it's not a huge problem. We would be happy as is if I did nothing further. Probably I shouldn't have mentioned the spike, it's not really the main point.

I do have to do something with the ceiling, it's 70's Artex loaded with Asbestos, I'm just wondering if I can get some acoustic benefit along the way, rather than just plaster boarding over and painting.



BIGmouthinDC said:


> Also need to know what frequency is the spike. We don't know if it is a floor ceiling resonance or a first reflection issue.


Room is 5.4m long x 4.4m wide x 2.54m high
REW says that's 17'3" x 14'5" x 8'3"

Floor ceiling resonance would be 68Hz, I'm not going to try to fix that with the ceiling, I'd need way more than 4".



BIGmouthinDC said:


> knowing the timing delay of the spike would also be useful. We also know nothing of the design or the room, position of the measurement, single or an average of all listening positions. Maybe diffusion instead of absorption would work. Just too many unknowns. I don't know enough on the topic to fix your problem but I know enough to recognize when a shotgun solution may not be the overall best strategy. Treating the entire ceiling with 4 inches will suck a lot of energy out of your soundtrack.


The thing is I don't really have a problem, other than needing to make the ceiling prettier and wanting to get some extra value from the work.

I actually really like dead rooms so it wouldn't be a concern to deaden further.

Maybe I should find some material to cover the ceiling fairly easily and neatly and if it has some small acoustic high frequency deadening that's a bonus.


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## BIGmouthinDC

you can actually mount fabric directly to a hard surface, it will look like quality wallpaper.


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## consman

I have a snap frame poster that I'm thinking about building an acoustic panel behind. Since the front would be covered with the poster, I'm thinking I would have to cut out the sides of the panel to allow the sounds to get inside. Wouldn't really cost me much other than time and was thinking it would be worth a shot. Has anyone tried something like this? Would it be worth doing?


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## dwander

consman said:


> I have a snap frame poster that I'm thinking about building an acoustic panel behind. Since the front would be covered with the poster, I'm thinking I would have to cut out the sides of the panel to allow the sounds to get inside. Wouldn't really cost me much other than time and was thinking it would be worth a shot. Has anyone tried something like this? Would it be worth doing?


I’m no expert but I think wouldn’t be worth the effort. I’m thinking the majority if not all of the sound would still reflect off the face of the poster frame.


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## consman

dwander said:


> I’m no expert but I think wouldn’t be worth the effort. I’m thinking the majority if not all of the sound would still reflect off the face of the poster frame.


Thanks, that's what I thought might be the response. Oh well lol


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## AndreNewman

BIGmouthinDC said:


> you can actually mount fabric directly to a hard surface, it will look like quality wallpaper.


Thanks, that's the sort of direction I'm looking into now.

Didn't the Aristocracy have fabric walls in many of the palaces of the 18th Century? It's all just coming full circle.


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## DMILANI

I’m about to install the Linacoustic to my screen wall. I am using Triad inwalls behind a Dreamscreen V7 AT screen. What’s the best way to properly measure and cut the Linacoustic to fit around the speakers and between the furring strips. Is it best to take careful measurements and just transfer those to the Linacoustic rolled out on the floor? And should I use scissors or a utility knife to cut it? Do you mark the measurements with a Sharpie?

Sorry for all the questions. Thanks in advance.


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## DMILANI

So I will answer my own question. I put up the Linacoustic yesterday and also installed my 3 Triad LCR inwalls. Linacoustic cuts like butter with a sharp utility knife or heavy duty scissors. I transferred measurements to the material on the floor and marked it with a black sharpie and cut to length. I did cut the openings in the Linacoustic for the speakers after I put it up on the wall (having only attached at the top at first). I had to reuse some old Insulshield on the bottom right of my screen wall since I ran out of Linacoustic (I only bought a small roll).

Here are some pics:









Photo Oct 10, 3 35 41 PM.jpg


Shared with Dropbox




www.dropbox.com













Photo Oct 10, 4 24 01 PM.heic


Shared with Dropbox




www.dropbox.com













Photo Oct 10, 4 24 13 PM.jpg


Shared with Dropbox




www.dropbox.com


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## jonohio

My room is finally substantially built after 4 years and I need to work on acoustic treatments. It’s amazing now, I can’t wait to dial it in.

I’d like to get treatment thoughts in-person from anyone localish to northeast Ohio.

Is there anyone around me that has been down this path before and would be willing to listen, offer thoughts, and have a beer with me?


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## fredxr2d2

jonohio said:


> My room is finally substantially built after 4 years and I need to work on acoustic treatments. It’s amazing now, I can’t wait to dial it in.
> 
> I’d like to get treatment thoughts in-person from anyone localish to northeast Ohio.
> 
> Is there anyone around me that has been down this path before and would be willing to listen, offer thoughts, and have a beer with me?


I don't know if he does something like that, but you could always try contacting Chad B, who is local to Ohio. http://www.hdtvbychadb.com/home-1.html


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## jonohio

Thank you, I’m actually on the list to have him do a projector calibration on his next trip!


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## Kevin4730

Apologize in advance if this was answered somewhere else, been searching around the last couple days. I want to add FSK/scrim/Kraft paper in my rear corners, but it’s such a small amount I don’t want a massive roll. Are there any key properties that are needed for acoustics? 

Standard brown paper from Home Depot would be my go to if it workshttps://www.homedepot.com/p/TRIMACO-Easy-Mask-2-9-ft-x-140-ft-Builder-s-Paper-35140/202040749
, I’ve also found this but it’s about $50 after shipping costs FRK Paper (Pack of 12 Sheets)
I’ve even heard wrapping paper could do the trick since it is thin enough. Any thoughts? I’d just need a few 2x4’ sections


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## Kevin4730

I didn’t want to overthink it and saw a 2’ wide roll of Kraft paper at ace hardware for $3 so I think this will do the trick.


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## lsuguy

I have a dedicated home theater room / 2 channel listening space in the bonus room of my house. The Screen wall is covered in GOM material and the backwall behind the screen wall is in the process of being completely covered on OC703. I also have two GIK bass traps in the corners behind the screen wall. As you can see in the photos I do have a few GIK panels that treated the first reflection points when this was a 2 channel space only. My question is, what else do I need to add to the room to affectively treat it. I am not scared of going with fabricmate walls etc but open to suggestions as I don't want to over deaden the room. Thanks in advance for any advice on what to do to improve things!


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## IMostlyPreferOLED

lsuguy said:


> I have a dedicated home theater room / 2 channel listening space in the bonus room of my house. The Screen wall is covered in GOM material and the backwall behind the screen wall is in the process of being completely covered on OC703. I also have two GIK bass traps in the corners behind the screen wall. As you can see in the photos I do have a few GIK panels that treated the first reflection points when this was a 2 channel space only. My question is, what else do I need to add to the room to affectively treat it. I am not scared of going with fabricmate walls etc but open to suggestions as I don't want to over deaden the room. Thanks in advance for any advice on what to do to improve things!
> View attachment 3192600
> View attachment 3192601


Nice room. I found it frustrating when I tried to have a dual purpose room. Now I have a HT that is over damped for stereo music but sounds great for films (thank you GIK), and a barely treated other room for just music. I know not everyone has that much space.

Tbh, I think my favorite way to listen to music is in the HT using all 5.1.4 channels.


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## MKaram

I'm trying to add a little absorption to my right side wall but I'm trying not to add much depth.
Is that any product worth applying that's 1/2" just for treating echo?

Or am I better off using a curtain?


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## nathan_h

Are you looking for a diy project or a commercial product?

1” is about the minimum for most commercial products, since even at that depth you end up with an unintended tone control where the high frequencies are absorbed but everything else is not. But it may be better than nothing (and is almost certainly better than curtains).

2” is much better and still pretty in obtrusiv.

Got photos on the space?


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## tidwelr1

lsuguy said:


> I have a dedicated home theater room / 2 channel listening space in the bonus room of my house. The Screen wall is covered in GOM material and the backwall behind the screen wall is in the process of being completely covered on OC703. I also have two GIK bass traps in the corners behind the screen wall. As you can see in the photos I do have a few GIK panels that treated the first reflection points when this was a 2 channel space only. My question is, what else do I need to add to the room to affectively treat it. I am not scared of going with fabricmate walls etc but open to suggestions as I don't want to over deaden the room. Thanks in advance for any advice on what to do to improve things!
> View attachment 3192600
> View attachment 3192601


IMO, sending pics to your GIK rep, and asking that person what they think is needed. That’s what I did and was actually requested from my GIK rep. With that said, the bare side walls back where the seating is probably needs something. That cavity where the window is might need something. I’m sure your GIK contact would know. With that said, what kind of speakers and subs do you have? Asking bc it looks like you spent a good bit more on the equipment compared to the speakers and subs. I could be wrong. 

Edit: do you have room to move your surrounds back behind the seating some some and then angle them towards the seating? I think that would be better than what your doing. It looks like the surrounds are really close to the outside seats. 


Sent from my iPhone using Tapatalk


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## MKaram

nathan_h said:


> Are you looking for a diy project or a commercial product?
> 
> 1” is about the minimum for most commercial products, since even at that depth you end up with an unintended tone control where the high frequencies are absorbed but everything else is not. But it may be better than nothing (and is almost certainly better than curtains).
> 
> 2” is much better and still pretty in obtrusiv.
> 
> Got photos on the space?


I don't mind using either a commercial or DIY product.

For a commercial product I've found polymax panels


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## lsuguy

tidwelr1 said:


> IMO, sending pics to your GIK rep, and asking that person what they think is needed. That’s what I did and was actually requested from my GIK rep. With that said, the bare side walls back where the seating is probably needs something. That cavity where the window is might need something. I’m sure your GIK contact would know. With that said, what kind of speakers and subs do you have? Asking bc it looks like you spent a good bit more on the equipment compared to the speakers and subs. I could be wrong.
> 
> Edit: do you have room to move your surrounds back behind the seating some some and then angle them towards the seating? I think that would be better than what your doing. It looks like the surrounds are really close to the outside seats.
> 
> 
> Sent from my iPhone using Tapatalk


Thanks for the advice. I agree I need more treatment than what I have going on now. I will reach out to GIK and see what they recommend.

Speakers are Sonus Faber Olympica IIs for LCR. Subs for Music are SVS SB3000 and Subs for Home Theater are two Mini Marty with UM18s behind the screen wall. I have plans to purchase JTR LCRs and essentially have two speaker setups, one for 2 channel and one for Home theater. The Sonus Faber sound great for music, but I feel like there are better options for home theater use.


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## nathan_h

MKaram said:


> I don't mind using either a commercial or DIY product.
> 
> For a commercial product I've found polymax panels


I have not used Polymax but reading their specs I’d say the 1” version looks reasonable. I’d hesitate to go with anything thinner, and if you can fit something thicker that will likely be much nicer. I

Gik is a popular choice. Acoustimac is another with some nicer looking options. And Audimute, while a little more expensive, does some interesting stuff that looks like wood or stone but is actually an effective absorbing panel.


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## MKaram

nathan_h said:


> I have not used Polymax but reading their specs I’d say the 1” version looks reasonable. I’d hesitate to go with anything thinner, and if you can fit something thicker that will likely be much nicer. I
> 
> Gik is a popular choice. Acoustimac is another with some nicer looking options. And Audimute, while a little more expensive, does some interesting stuff that looks like wood or stone but is actually an effective absorbing panel.


I'm thinking of hiding it behind fabric on wall using wall-mate clips.


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## nathan_h

That will look nice. But it would be a shame to spend all the time and money on the fabric system, and mess up the sound by using half inch panels.

If you are really just trying to control general echo in the room, putting six inch panels (or similar) on the ceiling will help kill a lot of echo, without acting like a tone control and sucking the life out of the treble in the room.

Are you considering super thin treatment on the walls because you don't have space? 

If it is about looks, perhaps consider printed panels that look like art? They can be a bit thicker and not look bad.


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## tidwelr1

lsuguy said:


> Thanks for the advice. I agree I need more treatment than what I have going on now. I will reach out to GIK and see what they recommend.
> 
> Speakers are Sonus Faber Olympica IIs for LCR. Subs for Music are SVS SB3000 and Subs for Home Theater are two Mini Marty with UM18s behind the screen wall. I have plans to purchase JTR LCRs and essentially have two speaker setups, one for 2 channel and one for Home theater. The Sonus Faber sound great for music, but I feel like there are better options for home theater use.


Those are nice speakers, but I just read a review that said essentially what you’re feeling. That there are other speakers that provide a larger soundstage or are better for home theatre. You seem to have the sub part covered I would think. I would work with your GIK contact to figure out the best next steps for your space. John Dykstra was the one I worked with. 


Sent from my iPhone using Tapatalk


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## abirdie4me

I'm starting a redesign of my dedicated theater room (no music listening) and want to acoustically treat it, but I don't know where to start. I've read the last 20 pages or so of this thread and my head is spinning. I think the room sounds pretty good as it is, but I don't really know how much better it can sound since I've never experienced a treated room. I'm not the most savvy audio guy and all the REW measurements are way over my head. My one complaint so far is that I don't get much detail from the overhead speakers in Atmos movies. From what I've read, it seems that treating the room might help bring out those details.

Here are some stats and pictures of my current setup, thanks in advance for any advice:

13 feet wide X 22 feet long X 10 feet high
7.2.4 system; LCR and Surrounds are Polk Audio 705/706C/702 f/x; in ceiling are Polk Audio 700 ls; 2 X 12" Monoprice Monolith THX Ultra subs ordered
Denon x4300h receiver, 2 Emotiva amps powering all speakers (upgrade of Denon on the agenda soon)
120" screen mounted directly to back wall
Floor is carpeted, no treatments anywhere currently
I have a lot of triple black velvet ordered, plan to cover all walls; currently get pretty bad reflections on ceiling and side walls that is degrading picture quality
Questions:

When the subwoofers arrive, what placement is recommended? Those suckers are heavy, don't really want to spend a day hauling them around different locations if I can help it
With the 4 in-ceiling speakers, would ceiling treatments make sense? Seems like they would mess up the sound from the Atmos speakers since they would hang lower and sort of block the sound path
Bass traps - should i go floor to ceiling in each corner with something like GIK tri-corner bass traps?
I will probably build frames to stretch the velvet over the walls; would it be worth it to get some of those ugly and cheap 2" acoustic panels from Amazon and completely cover the walls, then cover them with the velvet so it looks nice? Or would that make the room too 'dead', or potentially just not provide enough absorption to matter?
Should I just cover the walls with velvet and then add GIK panels strategically later?
I realize most of you are going to say that I need to take measurements, but that whole process is frankly a bit intimidating. I'm not looking for perfection, just want to make improvements to sound quality and the biggest focus is really visual improvement of the image and aesthetically improving the looks of the room.


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## squared80

abirdie4me said:


> I'm starting a redesign of my dedicated theater room (no music listening) and want to acoustically treat it, but I don't know where to start. I've read the last 20 pages or so of this thread and my head is spinning. I think the room sounds pretty good as it is, but I don't really know how much better it can sound since I've never experienced a treated room. I'm not the most savvy audio guy and all the REW measurements are way over my head. My one complaint so far is that I don't get much detail from the overhead speakers in Atmos movies. From what I've read, it seems that treating the room might help bring out those details.
> 
> Here are some stats and pictures of my current setup, thanks in advance for any advice:
> 
> 13 feet wide X 22 feet long X 10 feet high
> 7.2.4 system; LCR and Surrounds are Polk Audio 705/706C/702 f/x; in ceiling are Polk Audio 700 ls; 2 X 12" Monoprice Monolith THX Ultra subs ordered
> Denon x4300h receiver, 2 Emotiva amps powering all speakers (upgrade of Denon on the agenda soon)
> 120" screen mounted directly to back wall
> Floor is carpeted, no treatments anywhere currently
> I have a lot of triple black velvet ordered, plan to cover all walls; currently get pretty bad reflections on ceiling and side walls that is degrading picture quality
> Questions:
> 
> When the subwoofers arrive, what placement is recommended? Those suckers are heavy, don't really want to spend a day hauling them around different locations if I can help it
> With the 4 in-ceiling speakers, would ceiling treatments make sense? Seems like they would mess up the sound from the Atmos speakers since they would hang lower and sort of block the sound path
> Bass traps - should i go floor to ceiling in each corner with something like GIK tri-corner bass traps?
> I will probably build frames to stretch the velvet over the walls; would it be worth it to get some of those ugly and cheap 2" acoustic panels from Amazon and completely cover the walls, then cover them with the velvet so it looks nice? Or would that make the room too 'dead', or potentially just not provide enough absorption to matter?
> Should I just cover the walls with velvet and then add GIK panels strategically later?
> I realize most of you are going to say that I need to take measurements, but that whole process is frankly a bit intimidating. I'm not looking for perfection, just want to make improvements to sound quality and the biggest focus is really visual improvement of the image and aesthetically improving the looks of the room.


You should make a dedicated build thread. I would start by getting a bigger screen when you can.


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## abirdie4me

squared80 said:


> You should make a dedicated build thread. I would start by getting a bigger screen when you can.


The screen, projector, and AV processor are all on the list to upgrade, but that is probably a year or so away due to budget...also, I'm waiting to see the feedback on the new Z line of projectors from JVC before I drop $10k on a projector. So just trying to get the walls and ceiling velveted for now, and would like to address acoustic properties at the same time.


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## nathan_h

_I have a lot of triple black velvet ordered, plan to cover all walls; currently get pretty bad reflections on ceiling and side walls that is degrading picture quality_
Velvet on the walls wont help with this. But it will be nice in terms of making the room darker.

Depending on the kind of velvet, covering acoustic panels with it may be a bad idea If it is too thick the higher frequency sound will just bounce off it and never reach the panels. But it is great for making walls and ceiling black.

_When the subwoofers arrive, what placement is recommended? Those suckers are heavy, don't really want to spend a day hauling them around different locations if I can help it_
Since you have a rectangular room, and can close the door, it is likely that diagonal corners may work well. So like, one in the front left corner and one in the right rear corner.

Since you have two rows of seats, I would avoid placing both subs on the front wall. That can work well for ONE ROW, but with two rows of seats, putting both subs on the front wall will mean the rows likely get very different amounts of bass.

Middle of the front and back wall, or middle of each side wall, could also work well. But from the photos, it doesn't look like that is an option due to space and layout.


_With the 4 in-ceiling speakers, would ceiling treatments make sense? Seems like they would mess up the sound from the Atmos speakers since they would hang lower and sort of block the sound path_
Yes, ceiling treatment still makes sense. Think of the sound coming from the ceiling speakers like a cone. As long as your panels are a few inches away from the speakers, you should be fine.


_Bass traps - should i go floor to ceiling in each corner with something like GIK tri-corner bass traps?_
You can, and it would not harm things (except you need to leave space in two opposing diagonal corners for the subs).

That being said, if budget is an issue, this is not the place where I would spend money, first. By having two subs, you are already cancelling many of the bass modes in the room, so corner bass trapping, while almost always useful, is less critical for you. (Still helps, of course, because the dual subs handle bass modes up to c. 120 hz, even when crossed over at 80hz, and you will have some room modes up to 300 hz, but we are getting into the area where I would say it's the realm of measurement before deciding a lot of bass trapping is necessary.) 

Simply straddling the corners with some 6 inch panels is likely to be a fine choice.


_I will probably build frames to stretch the velvet over the walls; would it be worth it to get some of those ugly and cheap 2" acoustic panels from Amazon and completely cover the walls, then cover them with the velvet so it looks nice? Or would that make the room too 'dead', or potentially just not provide enough absorption to matter?_
Absolutely avoid covering all the walls with panels -- whether foam or fiberglass. That will definitely make the room too dead. 

Depending on the audible opacity of the velvet you have, it might also not work well to cover panels with the velvet. The velvet might reflect a lot of the high frequency energy instead of letting it pass through.

Send GIK photos and the dimensions of your room and they will make useful recommendations. (Obviously audio measurement etc is a more precise way to go but your room is not too complicated, and your speakers are pretty well behaved, so their generic advice is going to be useful.)

Here is my guess about what they will say:

Three 2'x4'x4" panels on each side wall. (If you can fit six inch panels instead, that would be better, but the 4" ones will do well.)
Two 4'x2' x6" panels on the back wall -- one under each speaker -- and two 2'x2'x6" panels on the back wall, one above each speaker.
Four 2'x4'x6" panels on the ceiling. (4" ones would work too.) Likely with their special hanging brackets for a ceiling.

Total of 14 panels.

Seems like a lot? If you actually measure the space, it's probably less than 15% of the walls and ceilings that will have coverage. And as long as you are under 20ish percent, you are good. (Some people prefer even more in a small room, but I wouldn't go there without testing and measuring.)

Note too that there are other vendors if GIK is back logged with orders, like Acoustimac, Audimute, and so on. Stick with fiberglass or similar insulation type material, and avoid foam. (There are a small number of expensive foam panels that can work okay, but they cost more than insulation, to achieve the same results, so it's really for special use cases.)


_ Should I just cover the walls with velvet and then add GIK panels strategically later?_
Yes, that is a fine choice. This way, the panels are unfettered by the velvet. 

Just keep in mind that the velvet is not an acoustic treatment. It is 99% just a visual treatment.


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## abirdie4me

Thank you Nathan for the detailed reply. I think I may need to suck it up and hire a designer and do it right, otherwise I may end up with paralysis by analysis and never get anything accomplished.


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## nathan_h

An expert can help a lot. Ive been impressed by the work of Matthew Poes of late. Sound Proofing | Poes Acoustic | United States

I don't know if he does rooms remotely (ie, you measure based on his instructions and he provides advice based on the measurements) or if you are near him (I think he is based in Florida).


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## Stephan Mire

Not sure if there are any GIK dealers commenting in the thread, but do they offer shipping to South Africa? I ordered 6 x 244 panels from them about 7 years ago, but if I browse their website my country is not listed for some reason.


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## Genifer Teal

Been following along a bit. General question about bass traps in a living room. They are typically 6 inches thick and placed on a wall. I have a large coffee table. I can fit 8 or more inches insert the table. Only the sides would be exposed. Could this work? 

I suppose a design is possible where 6 inches are under the table top and there is 6 inches (or more) space where the bottom of insulation is open to the floor. Would that work? 

I get the sense that the large surface really needs to face the sound waves head on. Trying to get creative for concealment.


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## AndreNewman

nathan_h said:


> If you are really just trying to control general echo in the room, putting six inch panels (or similar) on the ceiling will help kill a lot of echo, without acting like a tone control and sucking the life out of the treble in the room.


Can I ask a question about this comment? Of you and anyone else knowledgeable on this subject.

I hear this a lot, don't over treat, room will sound dead, soundstage will be gone, room will sound horrible.

I also hear a lot, Harman curve, boost bass and cut treble, Dirac slopes, house curves, tilt control. Our hearing is supposed to pick up treble more and bass less at lower volumes, Harman, Toole, Olive etc.

My issue is, one voice is saying don't over treat because treble will be attenuated, other voice is saying cut treble because it's too much at normal listening levels. Is there some middle ground where some "over" treatment attenuates the Treble at about the right amount to create a natural Harman curve, top bit anyway? Or are we talking about attenuating Treble in different ways and the effect isn't equivalent?

I should say that I really like the effect of a "dead" over treated room, I work in TV and often spend time in sound mixing rooms or commentary booths that are almost completely treated. The clarity of any sound heard in those places is amazing, even just conversation is a joy to hear.

I also like the idea of the theoretical concept that any reverberation experienced in a movie should be from the sound track, not added by the room. I don't have a dead enough Cinema room to test this out for myself.


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## squared80

AndreNewman said:


> Can I ask a question about this comment? Of you and anyone else knowledgeable on this subject.
> 
> I hear this a lot, don't over treat, room will sound dead, soundstage will be gone, room will sound horrible.
> 
> I also hear a lot, Harman curve, boost bass and cut treble, Dirac slopes, house curves, tilt control. Our hearing is supposed to pick up treble more and bass less at lower volumes, Harman, Toole, Olive etc.
> 
> My issue is, one voice is saying don't over treat because treble will be attenuated, other voice is saying cut treble because it's too much at normal listening levels. Is there some middle ground where some "over" treatment attenuates the Treble at about the right amount to create a natural Harman curve, top bit anyway? Or are we talking about attenuating Treble in different ways and the effect isn't equivalent?
> 
> I should say that I really like the effect of a "dead" over treated room, I work in TV and often spend time in sound mixing rooms or commentary booths that are almost completely treated. The clarity of any sound heard in those places is amazing, even just conversation is a joy to hear.
> 
> I also like the idea of the theoretical concept that any reverberation experienced in a movie should be from the sound track, not added by the room. I don't have a dead enough Cinema room to test this out for myself.


Don't make it complicated. First, you don't need 6" panels are your ceiling, as the previous post said.

The front soundstage should be very well treated.
Put 2" panels at key first reflection points: ceiling, side walls.
Put a couple 2" panels on the rear wall.
Put 4-6" panels in the corners of your room (from top to bottom, if possible).

Then, go run Audyssey or whatever room software your AVR/processor has.

Then you're done. If you don't like the sound, add or remove panels and rerun the software. It's all based on what you like.


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## AndreNewman

squared80 said:


> Don't make it complicated. First, you don't need 6" panels are your ceiling, as the previous post said.
> 
> The front soundstage should be very well treated.
> Put 2" panels at key first reflection points: ceiling, side walls.
> Put a couple 2" panels on the rear wall.
> Put 4-6" panels in the corners of your room (from top to bottom, if possible).
> 
> Then, go run Audyssey or whatever room software your AVR/processor has.
> 
> Then you're done. If you don't like the sound, add or remove panels and rerun the software. It's all based on what you like.


My question was more on the theory.

Not on anything specific to my or anyone else's room.


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## sdurani

AndreNewman said:


> My issue is, one voice is saying don't over treat because treble will be attenuated, other voice is saying cut treble because it's too much at normal listening levels. Is there some middle ground where some "over" treatment attenuates the Treble at about the right amount to create a natural Harman curve, top bit anyway? Or are we talking about attenuating Treble in different ways and the effect isn't equivalent?


The thicker the absorber, the lower in frequency it absorbs. To avoid absorbers acting as tone control (attenuating treble), use broadband absorption to absorb all the frequencies of the reflection (down to about 100Hz). Since you really like the effect of a dead over-treated room, stick to that approach for your home theatre. In this day and age of surround sound, there is no longer a need to use the room as a surround processor (unless you like that effect).

With broadband absorption, treatments are no longer a form of tone control, but instead just controlling spaciousness and envelopment to your liking. Once you do that, you can use the target curve to achieve the tonal quality you prefer. Treatments and tone control (target curve) have separate functions that don't have to overlap.


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## AndreNewman

sdurani said:


> The thicker the absorber, the lower in frequency it absorbs.


Got that, understood.





sdurani said:


> To avoid absorbers acting as tone control (attenuating treble),


This is really the crux of my question.

Why is this such a terrible thing and therefore to be avoided, when so many are saying "attenuate treble" with a house curve or Harman curve?

Is the attenuation I'm going to get if I "overtreat" with too thin absorption 20dB more than a Harman curve? I don't think so, in my experience so far, physical absorption is far more subtle than a house curve or a deft tweak of a tone control.



sdurani said:


> use broadband absorption to absorb all the frequencies of the reflection (down to about 100Hz). Since you really like the effect of a dead over-treated room, stick to that approach for your home theatre. In this day and age of surround sound, there is no longer a need to use the room as a surround processor (unless you like that effect).
> 
> With broadband absorption, treatments are no longer a form of tone control, but instead just controlling spaciousness and envelopment to your liking. Once you do that, you can use the target curve to achieve the tonal quality you prefer. Treatments and tone control (target curve) have separate functions that don't have to overlap.


Yes, got all that, not quite the question I'm asking. I realise they don't _have_ to overlap but I wonder why it's "so bad" if they do?

Maybe if I find I don't have treatment that's broadband enough, because it didn't fit or whatever, I then don't need as steep a treble cut in my house curve?


----------



## anjunadeep

sdurani said:


> The thicker the absorber, the lower in frequency it absorbs. To avoid absorbers acting as tone control (attenuating treble), use broadband absorption to absorb all the frequencies of the reflection (down to about 100Hz). Since you really like the effect of a dead over-treated room, stick to that approach for your home theatre. In this day and age of surround sound, there is no longer a need to use the room as a surround processor (unless you like that effect).
> 
> With broadband absorption, treatments are no longer a form of tone control, but instead just controlling spaciousness and envelopment to your liking. Once you do that, you can use the target curve to achieve the tonal quality you prefer. Treatments and tone control (target curve) have separate functions that don't have to overlap.


Related question. I'm working on a dedicated space and I think I'd like to put carpet down just for the "feel", but I'd like to use those commercial carpet squares (synthetic fiber) because here in Florida regular carpet can get kinda gross and the industrial stuff you can spill on and it won't grow mold if it gets wet somehow. As far as I can tell, it's the same stuff I see in commercial theaters (only a couple people make this stuff anyways).






Mohawk Group - Page Not Found


Mohawk Group




www.mohawkgroup.com





Should I consider putting an area rug at the floors first reflection point? Maybe something thick and "shag" on top of it? Or just treat the ceiling with a broadband panel and forget about the floor?

_edit_ Example of what I mean attached. Then if I got nasty over time (probably wouldn't since it wouldn't be in way of the foot traffic) I could just replace it.


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## sdurani

AndreNewman said:


> Is the attenuation I'm going to get if I "overtreat" with too thin absorption 20dB more than a Harman curve? I don't think so, in my experience so far, physical absorption is far more subtle than a house curve or a deft tweak of a tone control.


If you're determined to use treatment as tone control, then that's your prerogative. Most people find it easier to use tone control to do tone control, since it is easier and allows for greater precision to shape the frequency response. Treatments are more useful for controlling things that tone controls cannot, like spaciousness and envelopment. But that doesn't mean you have to use treatments that way. If you take time to experiment with different thicknesses of material and number of panels (coverage), you should be able to find a combination that attenuates the right treble range and in the amount you want.


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## sdurani

anjunadeep said:


> Should I consider putting an area rug at the floors first reflection point? Maybe something thick and "shag" on top of it? Or just treat the ceiling with a broadband panel and forget about the floor?


An area rug (shag or otherwise) is fine. Not a good idea to go further than that.

Back in 2009, the Fraunhofer Institute was researching acoustics for their new audio laboratory rooms, wondering whether carpeting was enough or whether additional absorption was needed at the first reflection points on the floor. 2" of absorption was enough to avoid the floor bounce cancellation. Measurements improved but listening tests told another story:


> 3.1.4. Subjective room assessment:
> 
> Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative – unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this.


Indeed, the one early reflection our human hearing has always heard, even when we're not in a room (i.e., outdoors), is the floor bounce. No surprise things sound _"unnatural"_ when it's not there.

https://www.iis.fraunhofer.de/conte...indtheNewStudiosandListeningRooms_AES7672.pdf


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## AndreNewman

sdurani said:


> If you're determined to use treatment as tone control, then that's your prerogative. Most people find it easier to use tone control to do tone control, since it is easier and allows for greater precision to shape the frequency response. Treatments are more useful for controlling things that tone controls cannot, like spaciousness and envelopment. But that doesn't mean you have to use treatments that way. If you take time to experiment with different thicknesses of material and number of panels (coverage), you should be able to find a combination that attenuates the right treble range and in the amount you want.


I'm not determined to do anything.

I'm questioning why the received wisdom is to not over treat because "you will kill treble" then in the next pearl of received wisdom "reduce treble with a house curve" is recommended?

Seems contradictory, I'm trying to understand if there's something else I'm missing.


----------



## anjunadeep

sdurani said:


> An area rug (shag or otherwise) is fine. Not a good idea to go further than that.
> 
> Back in 2009, the Fraunhofer Institute was researching acoustics for their new audio laboratory rooms, wondering whether carpeting was enough or whether additional absorption was needed at the first reflection points on the floor. 2" of absorption was enough to avoid the floor bounce cancellation. Measurements improved but listening tests told another story: Indeed, the one early reflection our human hearing has always heard, even when we're not in a room (i.e., outdoors), is the floor bounce. No surprise things sound _"unnatural"_ when it's not there.
> 
> https://www.iis.fraunhofer.de/conte...indtheNewStudiosandListeningRooms_AES7672.pdf


Oh, well, then maybe I just leave it the industrial carpet and call it a day. Sometimes less is more, eh?


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## fattire

AndreNewman said:


> I'm questioning why the received wisdom is to not over treat because "you will kill treble" then in the next pearl of received wisdom "reduce treble with a house curve" is recommended?
> 
> Seems contradictory, I'm trying to understand if there's something else I'm missing.


This is the case of using the right tool for the job more than anything else. Acoustic treatments address issues in the room; mainly problematic reflections that result in a blurry sound stage that has a lack of focus and clarity. Tone control (EQ) addresses the sound coming out of the speakers; the smoothness of the response at the listening positions.

A practical consideration is if you over treat a room, then no amount of EQ can overcome that. Preference > Reference. However, one of the points of "Reference" is getting us to a point where our "Preference" can be successfully applied.


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## sdurani

AndreNewman said:


> Seems contradictory, I'm trying to understand if there's something else I'm missing.


It seems contradictory only if you think they're both having similar effect: i.e., enough thin absorption will result in high frequency attenuation that resembles the treble range of the Harman curve. But too-thin absorbers don't just reduce treble, they reduce naturally occurring spaciousness & envelopment, which sounds unnatural to most listeners. This is why the results are described as dead. It's not because of attenuated treble. Also, what you describe as treble reduction in the Harman curve is more of a bass boost. The treble portion of the curve matches typical in-room response of loudspeakers, which sounds natural to most listeners. IF you start from the premise that both are basically doing treble attenuation, then it does seem contradictory to warn against one while encouraging the other. But they're doing different things.


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## AndreNewman

fattire said:


> This is the case of using the right tool for the job more than anything else. Acoustic treatments address issues in the room; mainly problematic reflections that result in a blurry sound stage that has a lack of focus and clarity. Tone control (EQ) addresses the sound coming out of the speakers; the smoothness of the response at the listening positions.
> 
> A practical consideration is if you over treat a room, then no amount of EQ can overcome that. Preference > Reference. However, one of the points of "Reference" is getting us to a point where our "Preference" can be successfully applied.


Thank you.

That makes prefect sense.


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## AndreNewman

sdurani said:


> It seems contradictory only if you think they're both having similar effect: i.e., enough thin absorption will result in high frequency attenuation that resembles the treble range of the Harman curve. But too-thin absorbers don't just reduce treble, they reduce naturally occurring spaciousness & envelopment, which sounds unnatural to most listeners. This is why the results are described as dead. It's not because of attenuated treble. Also, what you describe as treble reduction in the Harman curve is more of a bass boost. The treble portion of the curve matches typical in-room response of loudspeakers, which sounds natural to most listeners. IF you start from the premise that both are basically doing treble attenuation, then it does seem contradictory to warn against one while encouraging the other. But they're doing different things.


Ok, thanks.

That's making more sense to me.


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## tidwelr1

abirdie4me said:


> The screen, projector, and AV processor are all on the list to upgrade, but that is probably a year or so away due to budget...also, I'm waiting to see the feedback on the new Z line of projectors from JVC before I drop $10k on a projector. So just trying to get the walls and ceiling velveted for now, and would like to address acoustic properties at the same time.


You will be really surprised at how much room treatment helps the sound you hear. There’s so much less “bad noise” after treatment. In my situation, vocals are much clearer and pronounced and the overall sound in the room is more focused. Like you, the sound was already pretty good but it’s much better now. Since I’ve added them and watched more content my appreciation for them has increased a good bit. Mine are the 4” acoustic art panels from Gik. I have a 2” art panel directly behind the recliners too. 



















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## nathan_h

AndreNewman said:


> I'm not determined to do anything.
> 
> I'm questioning why the received wisdom is to not over treat because "you will kill treble" then in the next pearl of received wisdom "reduce treble with a house curve" is recommended?
> 
> Seems contradictory, I'm trying to understand if there's something else I'm missing.


I think several members have described this well already. So I wont repeat their answers other than to say I largely agree with their explanations.

I will ADD that the natural slope of the Harman curve is actually modeled on a room with NO TREATMENTS. That is, there is a natural roll off towards the high end in a flat speaker with wide even dispersion when it is used in a "normal" domestic room. It's the nature of how sound propagates in a room.

So, even if you have no treatments, if you have "good speakers" according the the CEA2034 specification (sometimes call the Spinorama) made famous by Harman but based on decades of research done by people in many different companies, universities and other research facilities, then in an "average" domestic room, you will see a drop off in treble response (or a rise in bass response, depending on how you want to describe it) naturally occur.

Given that, if you ALSO add thin absorption, you will have EVEN more drop off -- that will sound unnatural and act like a crappy tone control. What you want from treatment is to attenuate the room in a neutral way, not in a way that impacts some frequencies more than others.

How much is right? Well, the smaller the room, the more attenuation is wanted. This is often measured via a concept called RT60. (Technically, RT60 is related to reverberation, which small rooms don't have, but the measurement also tracks closely with how "live" a room sounds, so it is still a useful measurement even if it wasn't designed for use in domestic sized rooms.)

The oft mentioned 20 ish percent target is a nice rule of thumb. But in smaller rooms, or with speakers with less consistent off axis response, or rooms with lots of speakers, or in mastering studio situations where clinical analysis is key, you likely want more than the rule of thumb suggests.

In terms of measurement, a starting point might be to have a 15x30 home theater have a RT60 of .4 or .5 seconds max. But in a bedroom sized listening room, with multichannel sound, you might find that closer to .1 seconds RT60 is more pleasing. (And yes, that would mean going above the 20 percent of surface coverage with broad band absorption.)


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## iStorm

Hey guys! I am in the process of getting all of the materials for my first acoustic panels and had a few questions I cannot find the answers to. 

I am looking to make 4" broadband panels which is what my speaker manufacturer recommends, Revel, to treat the room. I was advised that it may not be a great idea to treat the early reflection point due to my speakers having great off axis response. So I am going to start by using the 4" panels to treat 2nd reflection (contralateral i believe). 

I'm assuming that a 4" panel means that i would use 1x4" wood and line it with 4" of insulation glass-wool (Ecose is what I plan to use). Will the insulation fit or would I need to use a bit thicker wood like 4.5 or 5"? Also, will I still be able to get a good amount of air gap between the wall and panel? I read that you want to have a 4" air gap with a 4" acoustic panel. 

Thanks for any help! I'm excited to finally hear what a semi treated room sounds like!


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## AndreNewman

iStorm said:


> I'm assuming that a 4" panel means that i would use 1x4" wood and line it with 4" of insulation glass-wool (Ecose is what I plan to use). Will the insulation fit or would I need to use a bit thicker wood like 4.5 or 5"? Also, will I still be able to get a good amount of air gap between the wall and panel? I read that you want to have a 4" air gap with a 4" acoustic panel.


I used Ecose for all my panels and bass traps, no formaldehyde, so no nasty smells for the first few weeks!

If you make the panels to size for the batts 1200mm x 600mm x 100mm or 1200mm x 455mm x 100mm or mutliples of. Then you don't need to cut and then there seems to be no particles from the insulation, the Knauf sealing process seems really good for this.

I found there's a lot of variation in the thickness of the batts, even after they have fully expanded. My first panels were made over sized with 120mm wood and 15mm corner braces at the back, so 105mm. I found the batts were less than 100mm and I have a gap between the fabric and the front of the panel.

The next ones I made with the 455mm batts to make 455x400mm bass traps without cutting, I made them exact sizes and now I can see some bulges here and there.

So probably a little oversized is best but it doesn't need to be much.

If you can design the panels without cutting batts it's a whole lot nicer experience, the Ecose is a lot nicer than Rockwool for loose particles. I did my loft with it too and no mineral dust in the air in there.


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## Dirt9

@ Andrenewman^^^^^ I have the the same size room except with a 8' ceiling. As far as sub placement I think you room would perform similar to mine.

Two subs placed on the front wall 4' feet in from each sidewalls have even response for one row ONLY about 9 feet from the back wall.

One sub dead center of the front and back wall will give you even response for TWO rows, one row at 9 ' from the back wall and one row at 6' from the back wall, BUT with less output because the subs are not coupled any more.

I spent countless hours measuring with REW and ultimately went with one sub in the front and one in the back of the room, and found that firing the front sub to the right and the rear sub to the left worked well in my room.

I did have to turn the gain up on the subs to get back the tactile response, but I have head room to spare. I strongly recommend you learn REW...Good luck 😁


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## AndreNewman

Dirt9 said:


> @ Andrenewman^^^^^ I have the the same size room except with a 8' ceiling. As far as sub placement I think you room would perform similar to mine.
> 
> Two subs placed on the front wall 4' feet in from each sidewalls have even response for one row ONLY about 9 feet from the back wall.
> 
> One sub dead center of the front and back wall will give you even response for TWO rows, one row at 9 ' from the back wall and one row at 6' from the back wall, BUT with less output because the subs are not coupled any more.
> 
> I spent countless hours measuring with REW and ultimately went with one sub in the front and one in the back of the room, and found that firing the front sub to the right and the rear sub to the left worked well in my room.
> 
> I did have to turn the gain up on the subs to get back the tactile response, but I have head room to spare. I strongly recommend you learn REW...Good luck


I think you tagged the wrong person?

Mid sidewalls are useless in this room, what works well is rear sides 3/4 to 5/8 for everything except a 20Hz null. Front corner to 1/4 or anywhere along the front wall fills in from 0 to ~45Hz and some help from 80-160Hz.

We have only a big sofa at 3/4 from front wall and an armchair so effectively one row.

I have 3 subs two rear side 3/4 one front side 1/4, all positions determined with REW and peq from MSO.
If I can pick up another matching sub I may raise my screen a little and put front subs under at 1/4 and 3/4 on the front wall.


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## iStorm

AndreNewman said:


> I used Ecose for all my panels and bass traps, no formaldehyde, so no nasty smells for the first few weeks!
> 
> If you make the panels to size for the batts 1200mm x 600mm x 100mm or 1200mm x 455mm x 100mm or mutliples of. Then you don't need to cut and then there seems to be no particles from the insulation, the Knauf sealing process seems really good for this.
> 
> I found there's a lot of variation in the thickness of the batts, even after they have fully expanded. My first panels were made over sized with 120mm wood and 15mm corner braces at the back, so 105mm. I found the batts were less than 100mm and I have a gap between the fabric and the front of the panel.
> 
> The next ones I made with the 455mm batts to make 455x400mm bass traps without cutting, I made them exact sizes and now I can see some bulges here and there.
> 
> So probably a little oversized is best but it doesn't need to be much.
> 
> If you can design the panels without cutting batts it's a whole lot nicer experience, the Ecose is a lot nicer than Rockwool for loose particles. I did my loft with it too and no mineral dust in the air in there.


Thanks for the info! I ordered 12 pieces of the Ecose insulation and I'm going to make 4" panels with 1x6" wood so there is 2" of air gap. I trust the Ecose more just knowing it doesn't have any formaldehyde in it.


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## AndreNewman

iStorm said:


> Thanks for the info! I ordered 12 pieces of the Ecose insulation and I'm going to make 4" panels with 1x6" wood so there is 2" of air gap. I trust the Ecose more just knowing it doesn't have any formaldehyde in it.


They make a bit fuss about it in their docs and all the places that I know of that make commercial panels Gik, Mafia, Bluefrog use the Knauf Ecose, that's good enough recommendation for me.


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## iStorm

AndreNewman said:


> They make a bit fuss about it in their docs and all the places that I know of that make commercial panels Gik, Mafia, Bluefrog use the Knauf Ecose, that's good enough recommendation for me.


Absolutely! We just got the ecose delivered but no one notified us and it was just sitting out in the rain and snow all day. Going to ask about a replacement since this stuff is probably ruined.


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## DarinS

abirdie4me said:


> The screen, projector, and AV processor are all on the list to upgrade, but that is probably a year or so away due to budget...also, I'm waiting to see the feedback on the new Z line of projectors from JVC before I drop $10k on a projector. So just trying to get the walls and ceiling velveted for now, and would like to address acoustic properties at the same time.


You dont need to spend 10k. I’d hope over to the LG HU810/AU810 owners thread. Very good projector once dialed in for $3k. Love mine so far


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## Venue

Is there any point in putting thin absorption panels behind a non-AT fixed frame screen?


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## BufordTJustice

Venue said:


> Is there any point in putting thin absorption panels behind a non-AT fixed frame screen?


There can still be benefits seen.

Can you be more specific about your use case?


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## Venue

BufordTJustice said:


> There can still be benefits seen.
> 
> Can you be more specific about your use case?


Well, it's rather simple, home theater in a rectangular living room, four bass traps in all four corners (middle of the wall), 1st reflection point absorption on rear wall, side walls, ceiling and a rug in beneath the center speaker, hardwood floor, diffusion on rear side walls, L/R speakers are placed in front of the front bass traps, subwoofers at 1/4th and 3/4th, probably a feet and a half from each front tower to the screen, there is perhaps two inches of available room behind the screen fabric once mounted on the wall, the frame of the screen is otherwise in contact with the wall.

I'm thinking, high frequencies will just bounce off the fabric, but maybe mid-lower frequencies will go through it even if it's a non-AT material? I have no treatment on the front wall except the bass traps in the corners, hence my thought on adding some behind the screen, because it's a rather large portion of the wall, which basically, even if treated, isn't visible once the screen is hung up on the wall, could be a clever idea, but also quite useless, would you know?
*
Edit*: Is mounting the screen on some distance blocks helpful for the sound to access the treatment?


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## BufordTJustice

Venue said:


> Well, it's rather simple, home theater in a rectangular living room, four bass traps in all four corners (middle of the wall), 1st reflection point absorption on rear wall, side walls, ceiling and a rug in beneath the center speaker, hardwood floor, diffusion on rear side walls, L/R speakers are placed in front of the front bass traps, subwoofers at 1/4th and 3/4th, probably a feet and a half from each front tower to the screen, there is perhaps two inches of available room behind the screen fabric once mounted on the wall, the frame of the screen is otherwise in contact with the wall.
> 
> I'm thinking, high frequencies will just bounce off the fabric, but maybe mid-lower frequencies will go through it even if it's a non-AT material? I have no treatment on the front wall except the bass traps in the corners, hence my thought on adding some behind the screen, because it's a rather large portion of the wall, which basically, even if treated, isn't visible once the screen is hung up on the wall, could be a clever idea, but also quite useless, would you know?
> *
> Edit*: Is mounting the screen on some distance blocks helpful for the sound to access the treatment?


Yes, that could be of some observable benefit, and for the reasons you stated.

To answer your last question (in the edit), it depends. If you are going to simply cover the area fully with absorbent material (rockwool or fiberglass batte), you never want it touching the screen (obviously). But a large airgap won't net you much additional benefit. I would want some free space between the screen and the material, regardless. Maybe an inch if you can get that? Not sure if an inch is feasible with only 50mm of space.


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## Venue

BufordTJustice said:


> To answer your last question (in the edit), it depends. If you are going to simply cover the area fully with absorbent material (rockwool or fiberglass batte), you never want it touching the screen (obviously). But a large airgap won't net you much additional benefit. I would want some free space between the screen and the material, regardless. Maybe an inch if you can get that? Not sure if an inch is feasible with only 50mm of space.


I understand, would leaving half an inch of free space between the screen and the absorption panels be better or worse than your desired inch? I mean I could probably make an inch, just add thicker distance blocks, but I would appreciate if you could explain as to why you would want that inch, does the sound need some free air to move around and access the panels? I hardly doubt that, because if the sound can and will travel through from one way, it would do the same coming through the other way as well, is it perhaps because you're more worried about the screen material?

Thanks a bunch!


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## BufordTJustice

Venue said:


> I understand, would leaving half an inch of free space between the screen and the absorption panels be better or worse than your desired inch? I mean I could probably make an inch, just add thicker distance blocks, but I would appreciate if you could explain as to why you would want that inch, does the sound need some free air to move around and access the panels? I hardly doubt that, because if the sound can and will travel through from one way, it would do the same coming through the other way as well, is it perhaps because you're more worried about the screen material?
> 
> Thanks a bunch!


You nailed it; screen material. That's my concern.

If you feel confident in a half-inch, swing for that fastball sir. 


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## KAYCEE2000

Going to be working on basstraps soon. i wanted to ask, how important are they? do i need the ones that are build like triangles or the flat panels?


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## Dirt9

Build 24x30x48" frames out of 1×2.,stack r30 insulation inside and wrap the frames with the cloth of you choice. Then load the 4 corners with them floor to ceiling. Measure with rew as you go. Large absorbers like these with smooth out your bass resonance making your room sound tight.


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## damnsam77

Well sh***! I am back after an 11 yr hiatus!!! I am gonna need some help in a few weeks  Good to be back on AVS


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## iStorm

Hey guys. We just built our home theater acoustic panels and we are trying to figure out where to hang them. 

Currently, we are focusing on the first early reflection points on the sidewalls for the LCR speakers in our 2 main seats. Do you have to have a certain amount of inches of the acoustic panel out to each side of the reflection points ? With the mirror method, we found the reflection points on the wall. If we put the 2nd acoustic panel centered over the reflection point of the opposite main speaker, then the reflection point for the center channel would be on the edge. Could we instead hang the panel so that the panel is centered between the main speaker reflection and center channel reflection so that each are covered equally on the panel? 

On the first acoustic panel, we have it so the middle of the reflection is in the middle of the panel for the speaker on the same side. This puts 12" on each side of that center point but if we do the method described above it would only be about 1.5" on each side with the second panel. 

Please let me know your thoughts. Thank you much!


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## nathan_h

Given that you probably have multiple seats, and sometimes lean back or recline and sometimes don't, and different people sit with a different posture and are a different height......it's not quite as exact a placement science as you might think. 

As a general guideline, if you can see the tweeter in a reflection where the panel is going, that is ideal, but even if that means sometimes its hear an edge, and a few times it slightly misses the panel, from one of the nine places tweeters are reflected for a three person couch, it is probably okay.


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## iStorm

nathan_h said:


> Given that you probably have multiple seats, and sometimes lean back or recline and sometimes don't, and different people sit with a different posture and are a different height......it's not quite as exact a placement science as you might think.
> 
> As a general guideline, if you can see the tweeter in a reflection where the panel is going, that is ideal, but even if that means sometimes its hear an edge, and a few times it slightly misses the panel, from one of the nine places tweeters are reflected for a three person couch, it is probably okay.


Hey thanks for replying! So we have two options then. The first point on the sidewall is easy since it is just the one speaker. We put the panel in the middle where the speaker reflects at the MLP. The two options we have for the center channel/next speaker reflection is to either do a panel for the center speaker by itself OR we can use the panel we have already and strategically place it so it hits the main speaker a bit AND the center channel. I just didn't know if the sound wave needed more space or if it's just fine that it hits the panel period. Hopefully that makes sense.


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## nathan_h

My bet is that you wouldn't be able to hear a difference between those two options, but it is free to try each.


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## iStorm

nathan_h said:


> My bet is that you wouldn't be able to hear a difference between those two options, but it is free to try each.


True. I have just read a lot of articles and barely ever hear about other enthusiasts, who are also installing acoustic panels, talk about doing a dedicated acoustic panel for the center channel. I just read that you mark the middle of the reflection at your seats and then that's where the middle of the acoustic panel should be. Also, I still don't know how high up on the wall the panel should go. I read 24" but my center channel is 21" up on the ground but angled towards the listening position.


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## nathan_h

It’s useful to trap the center channel as well. The wall reflection will tell you where that reflection happens.

Inwould tend to ignore ideas like a predetermined height and rely on the mirror trick to position the panels.


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## iStorm

nathan_h said:


> It’s useful to trap the center channel as well. The wall reflection will tell you where that reflection happens.


That's true! The reflection was at 30" up on the wall so it sounds like if i put the panels 24" up from the ground i will be fully covered. Do all of the woofers of the mains need to be covered as well though since they sometimes produce vocals? My lowest woofer on my Revel speakers is around 21" at the center of its cone.


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## nathan_h

If you can cover it, why not? That being said if the panels are not at least six inches thick they won’t do much to tame woofer reflections.


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## iStorm

nathan_h said:


> If you can cover it, why not? That being said if the panels are not at least six inches thick they won’t do much to tame woofer reflections.


Would i place the panels up about as high as where the bottom woofer starts or just in the middle of its cone woofer at the 21"? Thanks man


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## squared80

nathan_h said:


> If you can cover it, why not? That being said if the panels are not at least six inches thick they won’t do much to tame woofer reflections.


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## nathan_h

iStorm said:


> Would i place the panels up about as high as where the bottom woofer starts or just in the middle of its cone woofer at the 21"? Thanks man


I would cover as much of the reflections as possible and not worry about a little gap here or there.

Of course, luckily you have the panels, the speakers and the room, so you can try any variant and see what sounds best.

Even the experts don’t get it 100% right in the planning stage but have to test and adjust in room.


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## nathan_h

squared80 said:


> View attachment 3203363


Yep a great illustration that even the popular four inch panel isn’t really enough.

Here is even more detail showing to evenly tame from the bottom of a bass managed main‘s range, six inches is needed:


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## iStorm

nathan_h said:


> I would cover as much of the reflections as possible and not worry about a little gap here or there.
> 
> Of course, luckily you have the panels, the speakers and the room, so you can try any variant and see what sounds best.
> 
> Even the experts don’t get it 100% right in the planning stage but have to test and adjust in room.


Thanks man! I just didn't want to have to put a ton of holes in the wall and I was hoping to find placements that it would be good enough for now until we can build a dedicated home theater later on.


----------



## iStorm

Hopefully someone can please help. Here is a better explanation of the situation we are currently in.

We’re looking to hang up our acoustic panels, but we’re trying to decide if we need to add another panel to cover the center channel reflection or not.

We have a two-seat couch with a console. We used the mirror-method to determine where the reflections are for each main speaker and center channel for each of our seats. The center channel reflection is close to the contralateral main speaker reflection, but would not be fully covered if we center an acoustic panel over the contralateral reflection.

What we were thinking about doing is putting up one panel, and centering it between the reflections for the center channel and the contralateral speaker, that way each will be covered by the panel. However, the reflection points for one of our seats will land on the edge of the panel (for instance: on the right wall, the reflection of the center channel for our right-side seat will lay on the left edge of the panel, while the reflection of the contralateral speaker for our left-hand seat will lay on the right edge of the panel, with about half an inch of the panel leftover on each side of the reflection points).

My question is, is this sufficient to absorb those reflections? I’m debating putting a second panel right next to that one, so it’s one panel for the center channel reflection and one panel for the contralateral reflection. But my ipsilateral reflection is close enough that if I do two panels for the center channel and contralateral reflections, the ipsilateral reflection panel will have to be right next to those panels. Therefore, I’ll have three panels right next to each other along the side walls. My issue with doing this is that I might end up over absorbing the side walls. Also, in order to do this and still treat my back wall as planned, I would have to build one more panel.

So just to get people’s opinions, would I be sufficiently absorbing the contralateral and center channel reflections with one panel centered across those reflections, or do I need to have the two panels there?

Thank you in advance !


----------



## nathan_h

One panel should be fine.


----------



## iStorm

nathan_h said:


> One panel should be fine.


Thanks! I am probably going to just go with the one panel that goes edge to edge for the center channel reflection and the contralateral first reflection of the main speaker and see how we like it. I'm new to acoustic panels so I'm sure it will be a big improvement.


----------



## iStorm

I decided to place 2 panels to fully cover the center channel and contralateral opposite side main speaker first reflection. I am going to leave the ipsilateral first reflection off the main speaker bare for now since we have good Revel speakers. I may end up doing a combo panel there but want to try this first since I think full absorption there might kill the soundstage on my awesome Revel speakers.


----------



## jerrolds

My home theater is about 19.5 x 13.5 x 8.5' - battle wall is about 2.5' and listening position is about 10' after that (so at about 12.5', 64% of the room length) 

I'm planning on putting 5 2x4'x3" roxul panels behind the screen, panels on Left and Right walls (at first reflection points for both LR speakers) - which adds up to 13 panels. And 2 corner traps on the front wall

I also want to either put 4 panels on the ceiling or the back wall, or get 6x 2x2' Vicoustic DC2 diffuser panels and put them on the ceiling or back wall

Not sure if its worth getting diffuser panels for this space

Thoughts?


----------



## nathan_h

3" panels behind the screen don't do a lot. Too shallow to combat SBIR in most cases. Will take a little comb filtering from what the screen bounces back to the wall. But if you are trying to manage outlay, I'd worry about the back wall before the screen wall, since that is what messes with clarity even more. Even for people that like to leave first reflections untamed, they still tend to tame the wall behind the listening position.

And ideally those back wall absorbers would be six inches. (Minimum of 4".)

And if you want to get more fancy, this is a great resource. He has done many webinars based on the training classes he does at CEDIA. And while this one has some glitches due to a poor internet connection (mostly at the start) it is the deepest and most thorough version of his training I have seen. He has designed more than 1000 rooms.


----------



## jerrolds

I can potentially ask my builder to make 6" panels

Would diffusers 4x6' be worth it on the back or ceiling?


----------



## nathan_h

Depends on size, location, and type. But personally until I have say 15 or 20% coverage with absorbers, I wouldn't worry too much about it. I'm assuming this is a closed room and that mostly what you need to do is tame the overall amount of live-ness of the room, since your LS50 have nice off axis response and don't need a lot of treatment to help mitigate poor dispersion.

But the video I linked to explains the tradeoffs, type and location of diffusion versus absorption, so in the absence of measurements in your room, I would definitely follow the advice in the video as a starting point.


----------



## R B

So I have read through this forum a lot and going with the following approaches listed below to begin to finish my theater. Looking for some input and guidance on the below items. It is important to note that I have not taken any acoustic measurements in my theater yet as I am waiting for some final speakers to come in but this is the general approach I am taking. For a better understanding of my theater setup check out my Dedicated Thread. I am not planning on going wall to ceiling panels but just putting a few in places and to make the panels 2'x4' @ 2" thick except for the window where the dimensions are much larger. I soundproofed the room with Clips/GG etc. but decided to keep the window in for various reasons so now I need to put a panel in it. I will eventually also put in panels on the ceiling or just a fiber optic star ceiling.

I am debating the following items:

Whether to use Black Velvet next to the screen or GOM FR701 Black (Black - Guilford of Maine) for the Acoustic Material from floor to ceiling. I will also be putting black velvet panels around the screen wall. Not sure if I need the acoustic panels right next to the screen? My speakers will not be pointed in that general direction and I was wanting to black out near the screen.
Whether to use GOM FR701 Medium Grey Acoustic(Medium Grey - Guilford of Maine) Panels around the walls or a mixture of these and GOM Broadcast Graphite (Graphite - Guilford of Maine) or GOM Drift Storm (Storm - Guilford of Maine)? This is just an aesthetics question where I am maintaining darker colors but wanted some contrast in the room.
Whether I need to put any on the back wall or at least above the back bar wall? Above meaning within line of sight of the screen since behind the bar would not be hit directly with sound.
Also whether to use either of the four options I am looking at right now for the custom acoustic panel I will be putting in the window. This Acoustic Panel is coming from Acoustic ART panels, Decorative Acoustic Art sound Panels - The Perfect Harmony of Sight and Sound
*Dark Woods 1*


















*Dark Woods 2*


















*Matrix*


















*Space*


















Back Wall

Not sure if I need Acoustic Panels here or not or to rotate horizontally above the bar wall.


----------



## squared80

You need to order some samples so you can review sheen, etc.


----------



## Sitron_NO

I have a room with poor bass between 60-90Hz and I am thinking of building my own bass traps.
As you can see, my room is 347cm deep, and 381cm wide. And while I tried moving my MLP backwards toward the wall, in addition to move the sub towards the middle of the room, turning 90 degrees, and switch places with the front right speaker, the results where almost the same. (I played sweeps from the sub/LFE-channel only)
1920×1085 
















Before I start building my bass trap(s), I have some newbie questions:

If I build one with the dimensions 120x70x40cm (HxWxD), using Rockwool Soundslab will it make any noticeable difference? I would install it in the right back corner.
Do I need to put the bass trap right in the corner, or could I have a 6-7cm gap between the two walls on the bass trap?
Some say the more the merrier regarding bass traps, so would making a 2nd or 3rd be "required" before it would help my problem?
How important are placement of the bass traps? Could a make one and place it behind the couch? Could I make one with the dimensions 70x70x40cm (WxDxH), place it in the middle of the room and use it as a foot-rest?
The textile used on absorbents need to be acoustical transparent? Why? What are the negative effects of using a non-transparent textile?


----------



## R B

squared80 said:


> You need to order some samples so you can review sheen, etc.


Yeah did that. Ended up picking the material already and is on order.


----------



## R B

Sitron_NO said:


> I have a room with poor bass between 60-90Hz and I am thinking of building my own bass traps.
> As you can see, my room is 347cm deep, and 381cm wide. And while I tried moving my MLP backwards toward the wall, in addition to move the sub towards the middle of the room, turning 90 degrees, and switch places with the front right speaker, the results where almost the same. (I played sweeps from the sub/LFE-channel only)
> 1920×1085
> View attachment 3212411
> View attachment 3212412
> 
> 
> Before I start building my bass trap(s), I have some newbie questions:
> 
> If I build one with the dimensions 120x70x40cm (HxWxD), using Rockwool Soundslab will it make any noticeable difference? I would install it in the right back corner.
> Do I need to put the bass trap right in the corner, or could I have a 6-7cm gap between the two walls on the bass trap?
> Some say the more the merrier regarding bass traps, so would making a 2nd or 3rd be "required" before it would help my problem?
> How important are placement of the bass traps? Could a make one and place it behind the couch? Could I make one with the dimensions 70x70x40cm (WxDxH), place it in the middle of the room and use it as a foot-rest?
> The textile used on absorbents need to be acoustical transparent? Why? What are the negative effects of using a non-transparent textile?


I'm interested in the answers you get. I have not started this yet so I cannot be much help to you.


----------



## nathan_h

Sitron_NO said:


> I have a room with poor bass between 60-90Hz and I am thinking of building my own bass traps.
> As you can see, my room is 347cm deep, and 381cm wide. And while I tried moving my MLP backwards toward the wall, in addition to move the sub towards the middle of the room, turning 90 degrees, and switch places with the front right speaker, the results where almost the same. (I played sweeps from the sub/LFE-channel only)
> 1920×1085
> View attachment 3212411
> View attachment 3212412
> 
> 
> Before I start building my bass trap(s), I have some newbie questions:
> 
> If I build one with the dimensions 120x70x40cm (HxWxD), using Rockwool Soundslab will it make any noticeable difference? I would install it in the right back corner.
> Do I need to put the bass trap right in the corner, or could I have a 6-7cm gap between the two walls on the bass trap?
> Some say the more the merrier regarding bass traps, so would making a 2nd or 3rd be "required" before it would help my problem?
> How important are placement of the bass traps? Could a make one and place it behind the couch? Could I make one with the dimensions 70x70x40cm (WxDxH), place it in the middle of the room and use it as a foot-rest?
> The textile used on absorbents need to be acoustical transparent? Why? What are the negative effects of using a non-transparent textile?


Have you tried changing the smoothing option on that graph? In REW, using "psychoacoustic smoothing" often shows a very different picture.

(There is also something strange about those measurements which I'll address at the end of the post.)

If however, we take those measurements as they are, and you want to adjust the bass response in the room:

A). I'm not an expert at the math, but it seems like you would need very deep bass traps and lots of them if you are trying to tame in the 80hz range via traditional fiberglass methods. For example, creating a false wall where the TV is -- to fill this whole space with fiberglass (and then move the TV and stand and speakers forward by a meter of course). This assumes that you have fiberglass that is at least one meter thick.












B). My impression is that tuned bass traps with membrane that targets a general frequency range is more common solution for such a low frequency (but is not really a DIY project). The words to look for at things like "Pistonic Diaphragmatic Absorber"
They cost more than a subwoofer and deal with a much smaller range.








Vicoustic Super Bass Extreme Bass Traps (Set of 2)


Visually stunning, Vicoustic Super Bass Extreme bass traps provide low frequency absorption from 60-125 Hz. A premium bass trap based on the Wavewood™ panel



arqen.com












GIK Acoustics Scopus Tuned Membrane Bass Trap (T70)


The Scopus Tuned Membrane Bass Trap (T70) covers a tuned frequency range around 55 Hz to 100 Hz leaving mid- and high-end intact instead of deadening a room.




www.gikacoustics.com








C). All that being said, the *most common effective* solution these days is a second subwoofer:

When placed well and time aligned, can often help. But I wonder whether you moved the subwoofer enough to know whether this would help?

For example, did you measure the subwoofer when on the opposite wall next to the couch?

On both sides of the couch?

The other side of the TV?

Or "outside" the room through that large open doorway?

Near the middle of the right wall?

Behind the couch?

-----

I'm guessing you didn't move it very much since the variations are so small. 

I'm not saying that the 80hz dip would go away in other locations. (It might.) I'm saying that the other frequencies would change a lot more in most rooms, when moving the sub around the room.

To see what I mean, instead of moving the sub around, you can move the microphone around. If you don't see wild swings in the response between say the middle of the room, and along a wall, and in the corner, etc. something is amiss.


----------



## PixelPusher15

Figure I'd try here before making a new thread. 

I am looking to improve my acoustic treatment in my room and especially my bass response now that I have a working and capable sub. I'm getting a pretty big peak in the 30-40hz region and a null around 75-80hz (I'm not looking at my REW measurements right now so this is from memory). My room is 10.5x15x7'. Here is the mostly current state:


























I am in the middle of moving the L/R to outside the screen which will allow me to move that sub just a little bit to the right away from the center. I am planning on then stuffing the space with something like Rockwool or Safe and Sound that is wrapped in something to prevent loose fibers from floating around. Here's what the raw opening will be like when I'm done here:










My big question is what to do with the back wall with regard to bass traps and then as a secondary question of should I plan for adding a rear diffuser? I'm concerned that if I add a lot more treatment in the back for bass that I will overly deaden the room. Maybe I add something thin on top of the bass treatments to reflect some of the higher frequencies?

Here are 3 options I came up with ranging from less to more.

*A)*
The simplest option but I'm concerned it isn't enough.









*B)*
This option is a beefed-up version of A and uses the whole space I have between all the speakers back here. I actually really like the dimension this adds to the room but I am a bit concerned about the surrounds becoming a bit muffled with the traps so close. Maybe some panels with holes on them underneath the fabric at those reflection points?









*C)*
This one would be 16" of Rockwool or S&S for most of the wall but I would need to account for the speakers and create a sorta wide raceway for them to reach the MLP fully. Most expensive and complex build but possibly the best at treating the low frequencies.










Thanks for any tips, ideas or feedback y'all have.


----------



## sdurani

PixelPusher15 said:


> I am looking to improve my acoustic treatment in my room and especially my bass response now that I have a working and capable sub. I'm getting a pretty big peak in the 30-40hz region and a null around 75-80hz (I'm not looking at my REW measurements right now so this is from memory). My room is 10.5x15x7'.


Speed of sound divided by one of problem frequencies could be a clue to which room dimension is causing the problem. 1126 ÷ 75Hz = 15' (your room length). 75Hz is your room's second length mode, which nulls at the ¼ and ¾ points of room length.








IF your seating is near either of these locations (e.g., ¾ room length from the front wall), then you'll get a null around 75Hz. One way to confirm this is to measure a couple feet on both sides of the MLP to see if the null remains consistent (both those locations are the same distance from the front wall). If confirmed, the simplest solution is to move away from the null (slide the seating forward).


----------



## PixelPusher15

sdurani said:


> Speed of sound divided by one of problem frequencies could be a clue to which room dimension is causing the problem. 1126 ÷ 75Hz = 15' (your room length). 75Hz is your room's second length mode, which nulls at the ¼ and ¾ points of room length.
> View attachment 3214235
> 
> IF your seating is near either of these locations (e.g., ¾ room length from the front wall), then you'll get a null around 75Hz. One way to confirm this is to measure a couple feet on both sides of the MLP to see if the null remains consistent (both those locations are the same distance from the front wall). If confirmed, the simplest solution is to move away from the null (slide the seating forward).


Ah, yeah. I've looked at that before. My seating position is at 10.5' so I'm pretty much right there at the 3/4 length. No measurement I've done around the MLP has ever not shown this dip. Moving my couch is kinda not an option right now. I moved it forward to "increase" the screen size that I wanted but also to increase the angle of the front L/R speaker for better soundstaging. I really like it's position right now. I also don't think moving it back a foot would do much either. I saw the null there as well. 

Would treating the back wall with any of my options help?


----------



## sdurani

PixelPusher15 said:


> Would treating the back wall with any of my options help?


Wouldn't hurt to try thick (at least 6") absorbers on the back wall, between your two Rear speakers. They should have some effect in the 75-80 Hz range. Won't make the null disappear but could turn it into a dip that the room correction in your AVR can fix.


----------



## PixelPusher15

sdurani said:


> Wouldn't hurt to try thick (at least 6") absorbers on the back wall, between your two Rear speakers. They should have some effect in the 75-80 Hz range. Won't make the null disappear but could turn it into a dip that the room correction in your AVR can fix.


Can you you or someone educate me a bit more on this then. I thought that lower frequencies were worse in the corners and that's where I should try to absorb them. That was the thinking for the corner bass traps. I also have peaks around 30-40hz. Is it really best just to treat those peaks with EQ? I have so far but I thought room treatment is better than EQ....although I'm not sure why.


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## nathan_h

Nice room!

To impact those troublesome frequencies with passive trapping alone is tough. It needs to be very thick (more than a foot) and there needs to be lots of it. You are right that the corners give you the most bang for the buck. And yes if it ends up making the room too dead (I doubt it would) you can face them with some thick paper, cardboard, even thin wood with slots in it. But it will be an uphill battle.

There are tuned traps from places like GIK that do much better than piles of insulation for things below 100hz. You could ask them for their input given the data you have about your room. If traps are your main tool, I’d go with tuned traps.

But I suspect the biggest improvement may be a second matched subwoofer. Though a tuned trap may help, the second sub is going to be the biggest benefit. So once you’ve got more space behind the screen, putting one at 1/4 and one at 3/4 the room width will work some magic.

And while I know you said you can’t move your couch, that might be necessary no matter what trapping, multiple subs, and eq you do. Sitting at 67% or (not quite as good) 55% of the room length, and height, is often very beneficial. And even the dual sub setup may necessitate it since it wont kill front/back waves, just side to side ones.

(If you can’t move the couch then four smaller subs, one in each corner might be the solution.)

That said, can you share your measurments?


----------



## sdurani

PixelPusher15 said:


> I also have peaks around 30-40hz. Is it really best just to treat those peaks with EQ?


Yes, bringing down peaks is trivial for EQ.


> I thought room treatment is better than EQ....although I'm not sure why.


Using EQ to fix a problem at one location can create problems at other locations. Hypothetical example: suppose you have a 6dB peak at 35Hz, but only at the main listening position. 35Hz is flat at the seats on either side of the MLP. If you use EQ to cut that frequency down by 6dB, you will get rid of the peak BUT will create 6dB dips at that same frequency in the seats on either side. Almost never happens when you fix acoustical problems with treatment or placement.

While fixing acoustical problems physically is better than fixing them electronically, it isn't always practical. To tame a 35Hz peak you'd need a few feet of absorption. More practical to use a single band of EQ to pull down that peak.


----------



## BufordTJustice

PixelPusher15 said:


> Can you you or someone educate me a bit more on this then. I thought that lower frequencies were worse in the corners and that's where I should try to absorb them. That was the thinking for the corner bass traps. I also have peaks around 30-40hz. Is it really best just to treat those peaks with EQ? I have so far but I thought room treatment is better than EQ....although I'm not sure why.


EQ won't address any time domain issues (ringing/stored energy), but EQ can still be very effective for bass that low. Room treatments that would provide significant attenuation in that range would be.... cough.... quite large, in volumetric terms.


Sent from my iPad using Tapatalk


----------



## PixelPusher15

nathan_h said:


> Nice room!
> 
> To impact those troublesome frequencies with passive trapping alone is tough. It needs to be very thick (more than a foot) and there needs to be lots of it. You are right that the corners give you the most bang for the buck. And yes if it ends up making the room too dead (I doubt it would) you can face them with some thick paper, cardboard, even thin wood with slots in it. But it will be an uphill battle.
> 
> There are tuned traps from places like GIK that do much better than piles of insulation for things below 100hz. You could ask them for their input given the data you have about your room. If traps are your main tool, I’d go with tuned traps.
> 
> But I suspect the biggest improvement may be a second matched subwoofer. Though a tuned trap may help, the second sub is going to be the biggest benefit. So once you’ve got more space behind the screen, putting one at 1/4 and one at 3/4 the room width will work some magic.
> 
> And while I know you said you can’t move your couch, that might be necessary no matter what trapping, multiple subs, and eq you do. Sitting at 67% or (not quite as good) 55% of the room length, and height, is often very beneficial. And even the dual sub setup may necessitate it since it wont kill front/back waves, just side to side ones.
> 
> (If you can’t move the couch then four smaller subs, one in each corner might be the solution.)
> 
> That said, can you share your measurments?


Thanks for the explanation and tips. I have been wondering about a second subwoofer behind me after watching an old Dennis Erskine interview by Scott Wilkinson. Erskine said that a good way to perfectly place a subwoofer is by having two subwoofers opposed each other and then essentially changing the gain on the subs to move the phantom sub in the room. So my understanding was to have a sub in the back of the room at 25% and my current one at 75%. 

Anyway, here are my measurements. The full range one is supposed to just be my center since my Denon was on Pure Direct but I can't believe it is playing down to 20hz so something goofy is going on there. It also shouldn't have any EQ on it. The other is clearly my sub. These are dB averaged across my couch, 3 measurements. You can see my sub has that massive dip at 80hz but it also steadily trends down from 20 hz which isn't fun. My crossover is set at 60hz but I can't recall if Denon removes that or not in Pure Direct.










Previously, with lots of EQ'ing on my amp andin the Audyssey app I was able to acheive this at the MLP for my sub:


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## nathan_h

PixelPusher15 said:


> So my understanding was to have a sub in the back of the room at 25% and my current one at 75%.


This is a great starting point and in a lab environment, this would hold true. In a real room where dimensions are not an exact rectangle, where walls are not all equally constructed (like, one has a door), things will be a little different. But often the difference is such that some time alignment and EQ can work magic.

I dont know how far down the rabbit hole you want to go on the learning side BUT I think you are geek like me. So here is some more stuff to digest.


AVRANT (interview -- 



 -- with the godfather of bass who literally wrote the book and got a PHD in subwoofers; this link is to their summary of the interview but also has a link to the video interview AND to all the technical details including the key harman docs like https://www.harman.com/documents/multsubs_0.pdf; note that the AVRANT guys try to over simplify the science a bit and settle for Good Enough, assuming one isn't going to measure with REW and do alignment and EQ)








AV Rant #737: Interview with Todd Welti on Subwoofers - AV Rant


We are proud to present our interview with Todd Welti, Distinguished Engineer at Harman International Inc. Enjoy!



www.avrant.com






AV PRO EDGE (the best collection of Grimani presentations)








































AUDIOHOLICS (great that they let Grimani go into such detail, but due to the host, you get less science and info than with the AV PRO EDGE seminars)








Get the Best Bass for Your Home Theater P3: Wrapping it Up










-----
And then HTUGURUS and a couple of other folks ahve GREAT step by step guides to using a MINIDSP to align two subs, which really helps. I'm not sure the HTGURUS video is the easiest to follow since it assumes you need to learn how to use REW, and is unscripted, but I haven't seen a succinct video and this one is pretty accurate, even if long, so I'll post it here:

 Ep. 7 - REW Tutorial Multiple Sub setup with Minidsp for Great BASS! | Home Theater Gurus|


----------



## fattire

nathan_h said:


> This is a great starting point and in a lab environment, this would hold true. In a real room where dimensions are not an exact rectangle, where walls are not all equally constructed (like, one has a door), things will be a little different. But often the difference is such that some time alignment and EQ can work magic.
> 
> I dont know how far down the rabbit hole you want to go on the learning side BUT I think you are geek like me. So here is some more stuff to digest.
> 
> 
> AVRANT (interview --
> 
> 
> 
> -- with the godfather of bass who literally wrote the book and got a PHD in subwoofers; this link is to their summary of the interview but also has a link to the video interview AND to all the technical details including the key harman docs like https://www.harman.com/documents/multsubs_0.pdf; note that the AVRANT guys try to over simplify the science a bit and settle for Good Enough, assuming one isn't going to measure with REW and do alignment and EQ)
> 
> 
> 
> 
> 
> 
> 
> 
> AV Rant #737: Interview with Todd Welti on Subwoofers - AV Rant
> 
> 
> We are proud to present our interview with Todd Welti, Distinguished Engineer at Harman International Inc. Enjoy!
> 
> 
> 
> www.avrant.com
> 
> 
> 
> 
> 
> 
> AV PRO EDGE (the best collection of Grimani presentations)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> AUDIOHOLICS (great that they let Grimani go into such detail, but due to the host, you get less science and info than with the AV PRO EDGE seminars)
> 
> 
> 
> 
> 
> 
> 
> 
> Get the Best Bass for Your Home Theater P3: Wrapping it Up
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> -----
> And then HTUGURUS and a couple of other folks ahve GREAT step by step guides to using a MINIDSP to align two subs, which really helps. I can post those links a little later.


Holy crap dude. What a playlist of videos! A few of those are new to me so I’ll be diving in this afternoon.

@PixelPusher15 ; there is also multi-sub optimizer (MSO). Depending on your goals, the technologies you own, and technical abilities it can be a game changer.


----------



## nathan_h

fattire said:


> Holy crap dude. What a playlist of videos! A few of those are new to me so I’ll be diving in this afternoon.
> 
> @PixelPusher15 ; there is also multi-sub optimizer (MSO). Depending on your goals, the technologies you own, and technical abilities it can be a game changer.


I kind of think that when the pandemic first hit, Grimani had extra time and decided to do these extended video presentations as a way of upleveling the conversations and practices in the community AND a way to market his firm's expertise during what was probably a slow period for new projects. In any event, it's a gold mine of information if one takes the time to digest it all, imo. 

@fattire If you have some videos you like, please share. I recall a more succinct video on sub alignment that I think you posted, but cannot find the URL right now.

@PixelPusher15 can you share the URL of the Erskine video you mentioned?


----------



## PixelPusher15

nathan_h said:


> I kind of think that when the pandemic first hit, Grimani had extra time and decided to do these extended video presentations as a way of upleveling the conversations and practices in the community AND a way to market his firm's expertise during what was probably a slow period for new projects. In any event, it's a gold mine of information if one takes the time to digest it all, imo.
> 
> @fattire If you have some videos you like, please share. I recall a more succinct video on sub alignment that I think you posted, but cannot find the URL right now.
> 
> @PixelPusher15 can you share the URL of the Erskine video you mentioned?


Thanks for that playlist! I've got some watching to do. Here's the interview I watched. It's back from 2014 when 4K was super fresh and Atmos was just making it into residential theaters. The whole interview is pretty interesting but I have it queued up to the relevant part. Erskine explains it better than I did but I think my takeaway was accurate to my newb brain.


----------



## nathan_h

Yeah that’s an interesting interview. I suspect you’ll get a lot out of those subwoofer seminars in particular among the ones I posted. There is a lot of nuance and execution practice that he glosses over in his short answer since he is compressing a lot of important details that one needs to be aware of to actually succeed. In other words what he says is reasonable as far as he goes but is insufficient to guide a design and implementation.


----------



## fattire

nathan_h said:


> I kind of think that when the pandemic first hit, Grimani had extra time and decided to do these extended video presentations as a way of upleveling the conversations and practices in the community AND a way to market his firm's expertise during what was probably a slow period for new projects. In any event, it's a gold mine of information if one takes the time to digest it all, imo.
> 
> @fattire If you have some videos you like, please share. I recall a more succinct video on sub alignment that I think you posted, but cannot find the URL right now.
> 
> @PixelPusher15 can you share the URL of the Erskine video you mentioned?


It was probably the one linked below. Admittedly (disclaimer?), it's my video.


----------



## mtbdudex

fattire said:


> It was probably the one linked below. Admittedly (disclaimer?), it's my video.


Total sidebar.. seeing your name is “fattire” … this is my 3rd year on fattie’s … during winter it’s my ride, other 3 seasons swap a 29’er in there 
Ride studded tires in winter.
What’s your steed?



















Sent from my iPhone 11Pro using Tapatalk


----------



## nathan_h

fattire said:


> It was probably the one linked below. Admittedly (disclaimer?), it's my video.


Bingo. Yep. Thanks.


----------



## PixelPusher15

I’m building a short (4”) little platform in front of my screen that will span the whole front wall. I’m assuming I should fill this with insulation so I don’t get any resonances but is there any thing else I should keep in mind? It will be 4.5”x10.5’x2’

Related, I’m building a large ottoman for my couch and I have the option to either make it a place for blankets (empty during movies) or I can fill it with insulation as well. I could make the walls of it only 1/4” thick so maybe it could absorb some lower frequencies. The open cavity part will be about 10”x58”x26”. Thoughts on if it’s a good idea to fill it?


----------



## nathan_h

Yes loose insulation in the platform to reduce the drum like nature, and lots of glue in additional to screws to hold it together silently.

If the ottoman could have thin sides or even grills on a few sides, filling it with insulation is not a bad idea. But if you need the space for storage it might not be worth the sacrifice. Either way be sure it doesn’t block the center speaker etc.


----------



## rec head

My far from expert opinion is that you should go with storage in the ottoman. Unless it is part of a well calculated plan then it will just be a crap shoot if you get any real benefit. That is my experience with building things with the same intention as that. The storage has a definite benefit so take it.


----------



## Sitron_NO

nathan_h said:


> C). All that being said, the *most common effective* solution these days is a second subwoofer:
> 
> When placed well and time aligned, can often help. But I wonder whether you moved the subwoofer enough to know whether this would help?
> 
> For example, did you measure the subwoofer when on the opposite wall next to the couch?
> 
> On both sides of the couch?
> 
> The other side of the TV?
> 
> Or "outside" the room through that large open doorway?
> 
> Near the middle of the right wall?
> 
> Behind the couch?


Thanks for your reply, and sorry for my late reply. Having a bad back and moving a sub that weighs half my own body weight is not ideal  But after I bought a trolley, I have now taken measurements with the sub on different locations.

If you like, you can look at the REW measurements: Sub locations - 20220101.mdat. Firstly I moved the sub from front to back, on the right side of the room. Then placed in the middle of the room, top left corner, then back left corner and lastly behind the couch.

While moving down the right hand side, the dip moved downwards to 40Hz for each movement (and it flattened somewhat on the way)
Moving the sub to the front left side was almost identical to have it on the top right side.
Moving the sub to the back left resulted in a massive dip around 43Hz.
Moving the sub behind the couch resulted in a dip at 25-40Hz and a massive at 77Hz

While none was ideal, the best position is on the right hand side of the couch. A dip at 30-40Hz, but I'll mange. The range between 50-90Hz is now OK.

However, since the measurements differs so much while moving the sub, getting a second sub would be an improvement (and the best solution?)


----------



## nathan_h

Sitron_NO said:


> Thanks for your reply, and sorry for my late reply. Having a bad back and moving a sub that weighs half my own body weight is not ideal  But after I bought a trolley, I have now taken measurements with the sub on different locations.
> 
> If you like, you can look at the REW measurements: Sub locations - 20220101.mdat. Firstly I moved the sub from front to back, on the right side of the room. Then placed in the middle of the room, top left corner, then back left corner and lastly behind the couch.
> 
> While moving down the right hand side, the dip moved downwards to 40Hz for each movement (and it flattened somewhat on the way)
> Moving the sub to the front left side was almost identical to have it on the top right side.
> Moving the sub to the back left resulted in a massive dip around 43Hz.
> Moving the sub behind the couch resulted in a dip at 25-40Hz and a massive at 77Hz
> 
> While none was ideal, the best position is on the right hand side of the couch. A dip at 30-40Hz, but I'll mange. The range between 50-90Hz is now OK.
> 
> However, since the measurements differs so much while moving the sub, getting a second sub would be an improvement (and the best solution?)


Good progress! I’m on a mobile device for a few days so I can’t open the mdat file but what you describe sounds normal and usually a second Matched sub (easiest if it is exactly the same) can be placed in a way to mitigate that extreme variation.

You would still want to use eq but it would have less work and more success. Watch those videos above to get a sense of what it takes. The hardest part is learning to use REW and you have already learned that piece.

You will probably want to use a miniDSP 2x4 HD (double check that model number since I am going from memory) to time align the subs for best results though some people achieve the alignment using the phase knob on the subs.

There are several good threads on this. One is REW subwoofer alignment Video using MiniDSP complete...


----------



## squared80

ViciousDelicious said:


> It depends on the speakers dispersion pattern - ie how good is the sound that it's firing off-axis compared to on axis to decide how to best deal with early reflections and the reverberant field.
> 
> In my experience, and my experience only and what I've learned in theory and heard in practice is - you want minimum absorption in the high frequencies. The smaller the room the less of that you want. Bigger rooms might need some absorption to treat the RT times but smaller ones really lose of life by added absorption.
> 
> This is my room in 2016: Absorptive ceiling, and half of the wall panels were absorbing, the other half somewhat reflective in higher frequencies / absorbing in mid (the wooden panels).
> 
> View attachment 3219497
> 
> 
> 
> Ideally you should hire someone that has a good track record (and by that I mean rooms they can demo that sound good to YOU) in acoustics to find the exact proper treatment for your room.
> 
> 
> Alternatively if you don't have access to those kind of folks, you should just experiment by using a few diffusers/absorptive panels and placing them in various configurations and simply auditioning / measuring. Acoustics is art, measurements really do not tell you all the story, you need to both listen and measure every step of the way.
> 
> 
> View attachment 3219505
> 
> 
> Case in point - here's my office right now - it looks like a complete mess but I'm trying to find the absolute best arrangement for diffusion absorption in this living space to make my office setup sound the best I can before digital correction. I think I'm getting somewhere - here as well, I found that less high-mid absorption near the listening area and especially in the front wall next to the speakers works best. 1d/2d diffusion for the early reflection points.
> 
> I did fit basotect panels under the table, under the sofa, behind some furniture, behind the TV and in the corners of my side glass sliding door - that way I am able to treat the bad reflections that are dancing under the table/furniture (flutter echoing) and dampening the glass reflections for the reverberant space. So far this has been the best compromise of aesthetics and sound for me in this office living area. The entire front wall will be covered by the thinnest white fabric possible again avoid any loss of energy there. I will be measuring/listening to that also, and possible changing the acoustics again to find the best balance.
> 
> After working on this space for 5 years and having made all of the mistakes possible, I now realize that the only way to do this is to approach this acoustics first, prove it out with both listening and measurements and then making it pretty and tidy and beautiful. Maybe I should do a thread about the office as well.


So some of this post by @ViciousDelicious flies in the face of what I've read on these forums in regard to smaller rooms, so I'm just looking for clarification. I have a smallish, narrow room (25L x 10W x 8.5H). I plan on covering the entire front stage wall/ceiling behind my ATS with 2" Roxul 60, along with four 2" absorbers on the sides and two 2" absorbers on the ceiling for first reflections, and then a few on the rear wall, as well (to go along with 4-6" corner bass 'traps').

Other than the front stage, that's around the 15-20% absorption that I've read about. In a small room, is that too much absorption?


----------



## PixelPusher15

squared80 said:


> So some of this post by @ViciousDelicious flies in the face of what I've read on these forums in regard to smaller rooms, so I'm just looking for clarification. I have a smallish, narrow room (25L x 10W x 8.5H). I plan on covering the entire front stage wall/ceiling behind my ATS with 2" Roxul 60, along with four 2" absorbers on the sides and two 2" absorbers on the ceiling for first reflections, and then a few on the rear wall, as well (to go along with 4-6" corner bass 'traps').
> 
> Other than the front stage, that's around the 15-20% absorption that I've read about. In a small room, is that too much absorption?


I had the same questions and I'm still not entirely sure what to do in my space. I watched a bunch of stuff on YouTube and I encourage you to do the same since there is some varied approaches. Full absorption at the first reflections seems to be the most prevalent sentiment that is repeated around the forums but that's not what the professionals seem to advise. This video was a good one that @nathan_h shared above:
Expert Audio Series - Acoustics 101

It's long and there's a bunch that's not about what you are asking about but its still a good watch at 1.25x speed. Here's a screen grab of a proposed room that is really a mix along the whole wall:








Here's a long one with Grimani that is specifically about diffusion





Edit: this one that Nathan_h also linked is probably better to watch. Seems to go more in depth on this topic specifically:


----------



## ViciousDelicious

squared80 said:


> So some of this post by @ViciousDelicious flies in the face of what I've read on these forums in regard to smaller rooms, so I'm just looking for clarification. I have a smallish, narrow room (25L x 10W x 8.5H). I plan on covering the entire front stage wall/ceiling behind my ATS with 2" Roxul 60, along with four 2" absorbers on the sides and two 2" absorbers on the ceiling for first reflections, and then a few on the rear wall, as well (to go along with 4-6" corner bass 'traps').





PixelPusher15 said:


> I had the same questions and I'm still not entirely sure what to do in my space. I watched a bunch of stuff on YouTube and I encourage you to do the same since there is some varied approaches. Full absorption at the first reflections seems to be the most prevalent sentiment that is repeated around the forums but that's not what the professionals seem to advise. This video was a good one that @nathan_h shared above:


I think it depends on what frequencies we are discussing - bass is something you most likely need to treat, depending on the shape of the room and how much bass is leaking outside (ie if the construction is a bunker or not) - best to measure and see. Having more subs helps to linearize the response.

As for mid-high frequencies I personally really can't stand it. Maybe it's just Alcons (since they have a great 90 degree dispersion) but my brain just feels discomfort whenever there is absorption. I always, always preferred diffusion in the tests we did here. People recommend 1d diffusion for the early reflection points, 2d diffusion for the rest.

I think this discomfort comes from the lack of balance between the direct sound and the reflected reverberant field, and the best I can describe it is that my brain feels pressure, like I can't relax and just be lost in the movie/music. Something is wrong, you try to compensate for it with volume, EQ, response curve but none of it works and only makes it sound worse. Acoustics is the most fundamental aspect of any room and in my opinion it's more important than gear, speakers, cables, room correction. 

I've heard the same speaker before and after treatement in multiple stages here and I can tell you it's like listening to a new speaker all together. I'm not exaggerating, the difference is profound. If you do not have good acoustics, you're not hearing your speakers and what they can really sound like.

What I can whole-heartedly recommend is getting the material in the room (diffusers, absorption) and just playing with it. Doing a temp install, measuring/listening. That is really the only way to be certain that you're getting the best sound in your room. None of this stuff works on paper, every room is different and every speaker works differently in every room. You just have to experiment a bit to get the best result. Of course I'm not saying that there should be no planning / proper acoustical design and foresight here, but to really get the best you need to take the extra step and audition and try things on top of the basic plan.


----------



## nathan_h

squared80 said:


> So some of this post by @ViciousDelicious flies in the face of what I've read on these forums in regard to smaller rooms, so I'm just looking for clarification. I have a smallish, narrow room (25L x 10W x 8.5H). I plan on covering the entire front stage wall/ceiling behind my ATS with 2" Roxul 60, along with four 2" absorbers on the sides and two 2" absorbers on the ceiling for first reflections, and then a few on the rear wall, as well (to go along with 4-6" corner bass 'traps').
> 
> Other than the front stage, that's around the 15-20% absorption that I've read about. In a small room, is that too much absorption?


The videos @PixelPusher15 mentions are good. If you have the time/interest to watch ten hours on these topics, you can learn a lot by watching those and their companion videos on the same channels featuring Grimani -- some of which will be directly applicable to your room and some of which will just be the principles behind it all.

To be specific about your proposal:

2" panels are not ideal, since they will trap treble more than midrange and bass. Ideally, you use BROADBAND absorption, which traps "all" frequencies similarly. Realistically, you can't get down to 100hz very easily, but by using six inch panels, you do a lot better than 2" panels, if you can make the space for them. Front and rear wall are good places for this since it seems like you have lots of depth.

--

Regarding bass traps: These can be useful but I have found the biggest benefit is simply to use two matched subs, and set them up correctly, to manage room modes. This tends to achieve results that would otherwise take SIX FEET of bass trapping.


----------



## Snoochers

I have a home theatre about 16x22x9. My understanding is I need to treat about 30% of the surface area with diffusion and absorption. Questions:

1. I think surface area includes the four walls and ceiling but not the floor, correct? So if I have a 10x10x10 cube the surface area would be 500sqft (100+100+100+100+100) and I should have about 150sqft of treatment?

2. I loaded up my front wall with insulation behind the acoustically transparent screen. I mean the whole thing. This seems to be common practice to prevent unwanted reflections in the front. My front wall accounts for 16% of my surface area, so I'm already basically tapped out in terms of absorption. This leaves me with a few options:

(a) I leave my front fully insulated and barely add any absorption to the rest of the room (seems like a bad idea).
(b) I ignore the front wall and add treatments to 30% of the remaining four surfaces, which would bring my total to about 40%.
(c) Remove half of the front insulation and add it elsewhere (a real hassle but doable). This would leave me open potentially to unwanted reflections. My front also acts as a huge bass trap (it is actually 20" deep).

Any guidance would be much appreciated!


----------



## squared80

Here ya go...


----------



## nathan_h

Snoochers said:


> Any guidance would be much appreciated!


The video @squared80 links to above is an excellent place to start. The good thing about that video is it explains WHY people talk about these recipes and rules of thumb like what you are quoting, so you understand the recipe and can adapt it to your specific room, and not just blindly adopt a goal.

----

A few things I would consider in your shoes: If absorption isn't at least four inches thick, it's worth doing less coverage but thicker, so that instead of it acting like a tone control, it acts in a more consistent way across the frequency range. (Six inches is notably better, but sometimes impractical.)

I would definitely want to have the absorption in multiple places around the room and not all on one wall. I realize you feel like you have maxed out just by what you have in the front, but remember, the floor is needed for the calculation, so you don't have quite as much as you think. 

And if you did the two inch linacoustic behind the screen kind of treatment I don't know that that counts much for these purposes. That helps with the comb filtering an acoustic screen can engender, but doesn't do much more.

Finally, you can try adding a few panels around the room without touching the front wall and see what it sounds like. No law says you have to keep them all. And if you want to get more scientific, you can use REW to measure the RT60 in the room. What you want is to see something like .2-.4 (small room - larger room) RT60 across the frequency range down to the room transition frequency (say, 250hz depending on room size) and similar at all the frequencies from there, up. If you start to hit .1 seconds for RT60 across the frequencies, you have gone too far. .2 might sound too dead in your room, given it's size. 

Anyway, check out that video and you'll get a sense of what is possible and, more importantly, WHY people have come up with these seemingly arbitrary guidelines. Once you know the WHYs you can choose how you want to solve the issues.


----------



## Snoochers

nathan_h said:


> The video @squared80 links to above is an excellent place to start. The good thing about that video is it explains WHY people talk about these recipes and rules of thumb like what you are quoting, so you understand the recipe and can adapt it to your specific room, and not just blindly adopt a goal.
> 
> ----
> 
> A few things I would consider in your shoes: If absorption isn't at least four inches thick, it's worth doing less coverage but thicker, so that instead of it acting like a tone control, it acts in a more consistent way across the frequency range. (Six inches is notably better, but sometimes impractical.)
> 
> I would definitely want to have the absorption in multiple places around the room and not all on one wall. I realize you feel like you have maxed out just by what you have in the front, but remember, the floor is needed for the calculation, so you don't have quite as much as you think.
> 
> And if you did the two inch linacoustic behind the screen kind of treatment I don't know that that counts much for these purposes. That helps with the comb filtering an acoustic screen can engender, but doesn't do much more.
> 
> Finally, you can try adding a few panels around the room without touching the front wall and see what it sounds like. No law says you have to keep them all. And if you want to get more scientific, you can use REW to measure the RT60 in the room. What you want is to see something like .2-.4 (small room - larger room) RT60 across the frequency range down to the room transition frequency (say, 250hz depending on room size) and similar at all the frequencies from there, up. If you start to hit .1 seconds for RT60 across the frequencies, you have gone too far. .2 might sound too dead in your room, given it's size.
> 
> Anyway, check out that video and you'll get a sense of what is possible and, more importantly, WHY people have come up with these seemingly arbitrary guidelines. Once you know the WHYs you can choose how you want to solve the issues.


Thanks. I'll watch the video. I've seen three videos from him so I wasn't sure what else would be added but it is worth a look. FYI all my treatments will be 4" or more and as I mentioned behind the screen is about 20". 

You mentioned floor is needed for the calculation. Are you saying when they say 30% of area should be treated they're counting the floor? So if I have a 10x10x10 cube that means 600 square feet of area which means 600x30% optimal coverage? I know we're getting into the dirty details here but that would change my calculations significantly. My floor is 25% of the room's surface so it counts for a lot.

I have REW and my RT60 looks around .25 down to about 200hz and 300-400 down to about 50hz. This is with chairs and blankets and the front and rear walls done, but not either side walls or ceilings.


----------



## nathan_h

Snoochers said:


> RT60 looks around .25 down to about 200hz


If that is consistent from 200 to 20k hertz, that should be great.



Snoochers said:


> So if I have a 10x10x10 cube that means 600 square feet of area which means 600x30% optimal coverage?


Right, though the RT60 measurement is better than a percentage of wall space for figuring out how much is enough.

You might want to experiment with moving some stuff around but it sounds like you probably have enough absorption in the room. From here the effort would be to dial in the sound such as does the soundstage place instruments clearly? Is dialog easy to understand? Etc. That could be influence by changing the plac,ent of some absorption or adding diffusion etc.


----------



## Snoochers

nathan_h said:


> If that is consistent from 200 to 20k hertz, that should be great.
> 
> 
> 
> Right, though the RT60 measurement is better than a percentage of wall space for figuring out how much is enough.
> 
> You might want to experiment with moving some stuff around but it sounds like you probably have enough absorption in the room. From here the effort would be to dial in the sound such as does the soundstage place instruments clearly? Is dialog easy to understand? Etc. That could be influence by changing the plac,ent of some absorption or adding diffusion etc.


This is exactly the problem though. My belly is full but I've only had an appetizer. The RT60 suggests I have enough absorption and diffusion but I haven't treated 3 out of my 5 surfaces so I'm likely not achieving the delicious sound croissant Mr. Grimani talks about. It seems like a good idea to add treatments to ceiling and two side walls but I reckon my RT60 might drop too low. I'm going to custom make my panels based on the number and size requirements so it's not like I have them laying around and can play around. I'll be building them based on what I think I need.

I also have a pretty significant dip from 60-160hz which I think may be related to reflection interference.


----------



## nathan_h

It could be. I would plug your room dimensions and speaker locations into an SBIR calculator and see.

Or, you can move the speakers, remeasure, and see if the dip changes.

Or, if you are convinced it is SBIR, you can move the speakers CLOSER to the wall boundaries, raising the frequency at which SBIR happens, making it trappable with a six inch thick trap.

HOWEVER: Usually a dip is not that wide. That's more than an OCTAVE being lost! You should probably post your REW results. It's unlikely SBIR is causing that.


----------



## Snoochers

nathan_h said:


> It could be. I would plug your room dimensions and speaker locations into an SBIR calculator and see.
> 
> Or, you can move the speakers, remeasure, and see if the dip changes.
> 
> Or, if you are convinced it is SBIR, you can move the speakers CLOSER to the wall boundaries, raising the frequency at which SBIR happens, making it trappable with a six inch thick trap.
> 
> HOWEVER: Usually a dip is not that wide. That's more than an OCTAVE being lost! You should probably post your REW results. It's unlikely SBIR is causing that.


Thanks for this. Here is my SPL response from REW followed by my RT60. I had not zoomed in much before on the RT60 but I brought it closer. I do seem to have more absorption around 160hz so perhaps that explains the drop?


----------



## nathan_h

I would guess the frequency response dip around 100 might be solvable via adjusting the crossover point between the mains and the subs.


----------



## sdurani

Snoochers said:


> The RT60 suggests I have enough absorption and diffusion but I haven't treated 3 out of my 5 surfaces so I'm likely not achieving the delicious sound croissant Mr. Grimani talks about.


Unless you've heard Grimani's rooms, you don't know whether his approach would result in something that sounds good to you or not. So don't worry about what he thinks is delicious, concentrate on your own preference. Rather than go by percentage of coverage across all surfaces, think about which directions you want to tame reflections. 

For example: reflections off the front wall will come from the same direction as the L/C/R speakers and will muddy the front soundstage. Absorption there will help with soundstage articulation and clearer imaging. The L/C/R speakers are pointing at the back wall, so absorption will help behind the listeners. Reflections off the side walls come from outside the soundstage, so they won't muddy the sound but will widen the soundstage. Most people prefer that, so side wall absorption is optional (no right or wrong, just what you prefer). 

By the time you're done, will you have achieved the percentage of treatment vs surface area in your room that Grimani recommends? Does it matter?


----------



## Snoochers

nathan_h said:


> I would guess the frequency response dip around 100 might be solvable via adjusting the crossover point between the mains and the subs.


This makes sense to me, but I would’ve thought my anthem arc correction would’ve solved that easily enough. I think something else is going on. EDIT: I recall moving my crossover frequency lower and higher to address this but crossover never fixed it.


----------



## Snoochers

sdurani said:


> Unless you've heard Grimani's rooms, you don't know whether his approach would result in something that sounds good to you or not. So don't worry about what he thinks is delicious, concentrate on your own preference. Rather than go by percentage of coverage across all surfaces, think about which directions you want to tame reflections.
> 
> For example: reflections off the front wall will come from the same direction as the L/C/R speakers and will muddy the front soundstage. Absorption there will help with soundstage articulation and clearer imaging. The L/C/R speakers are pointing at the back wall, so absorption will help behind the listeners. Reflections off the side walls come from outside the soundstage, so they won't muddy the sound but will widen the soundstage. Most people prefer that, so side wall absorption is optional (no right or wrong, just what you prefer).
> 
> By the time you're done, will you have achieved the percentage of treatment vs surface area in your room that Grimani recommends? Does it matter?


Thanks for this. I do believe Grimani knows what he’s talking about especially since it’s mostly the same thing Floyd Toole and others are saying. I certainly trust their opinions more than my own judgment !


----------



## nathan_h

Snoochers said:


> This makes sense to me, but I would’ve thought my anthem arc correction would’ve solved that easily enough. I think something else is going on. EDIT: I recall moving my crossover frequency lower and higher to address this but crossover never fixed it.


The other thing to try is adjusting the distance setting for the sub. This can sometimes significantly impact the crossover region and how things sum.

I will measure at two foot increments over the full range of adjustment to find the best integration when I’m really trying to dial it in.


----------



## Snoochers

nathan_h said:


> The other thing to try is adjusting the distance setting for the sub. This can sometimes significantly impact the crossover region and how things sum.
> 
> I will measure at two foot increments over the full range of adjustment to find the best integration when I’m really trying to dial it in.


The problem is that I still need to add treatments to the room so it doesn't really make sense to me to get too deeply into this. It is sort of a chicken or egg situation. There is a problem so I think perhaps treatments can help, but then again my treatments will change things and perhaps the problem will just go away or be different altogether! I will put up some treatments and see where it gets me. I just don't know quite how much yet.


----------



## fattire

Snoochers said:


> The problem is that I still need to add treatments to the room so it doesn't really make sense to me to get too deeply into this. It is sort of a chicken or egg situation. There is a problem so I think perhaps treatments can help, but then again my treatments will change things and perhaps the problem will just go away or be different altogether! I will put up some treatments and see where it gets me. I just don't know quite how much yet.


Treatments will have zero impact on the sub-mains integration at the crossover. A dip there is caused by phase cancellation. Phase isn’t impacted by treatments.


----------



## Snoochers

fattire said:


> Treatments will have zero impact on the sub-mains integration at the crossover. A dip there is caused by phase cancellation. Phase isn’t impacted by treatments.


Thanks. How is this fixed then? I’ve never addressed phase cancelation. EDIT: I have two subs on opposite walls near midpoints based on best practices. Can’t really move them.


----------



## nathan_h

Snoochers said:


> Thanks. How is this fixed then? I’ve never addressed phase cancelation. EDIT: I have two subs on opposite walls near midpoints based on best practices. Can’t really move them.


Before I insult you by dumping a lot of references, procedures, videos, etc, on you, I am doing to ask a couple questions to understand what might be most useful. NO DISRESPECT INTENDED. (And, FYI, I am not among the top tier experts in this area so this is just a baseline.)

First, it is GREAT you have two subs. Are they the same model? If not, are they at least similar in output and extension?

Have you level matched or gain matched your two subs? Have you "time aligned" the two subs to one another? This is most often done using a miniDSP unit. However, if your subs have their own volume knobs (most do) and variable phase knobs (many do) then it is possible you did both of these steps without a miniDSP.

Neither of the two steps above can be done with ARC on most Anthem units.

Then, figuring out the best crossover settings, and the distance setting for the summed subs, would be the next step. (Note that "distance setting" has nothing to do with physical distance. It's really more of a way to phase align the subs -- summed in a group already -- with the mains.) I'm inferring that you haven't done these two steps based on the discussion.

---

In short, @fattire is right, and even more right since issues around 100 hz aren't going to be significantly impacted by more room treatment unless it is tuned bass traps....and that wouldn't be the first place to start, but, rather, something to consider is subwoofer setup and integration doesn't solve things.

---

The good news is you have two subs and you know how to use REW. Those pieces are actually the biggest stumbling blocks for most people!



(PS chances are good that the placement of your subs is going to be workable.)


----------



## Snoochers

nathan_h said:


> Before I insult you by dumping a lot of references, procedures, videos, etc, on you, I am doing to ask a couple questions to understand what might be most useful. NO DISRESPECT INTENDED. (And, FYI, I am not among the top tier experts in this area so this is just a baseline.)
> 
> First, it is GREAT you have two subs. Are they the same model? If not, are they at least similar in output and extension?
> 
> Have you level matched or gain matched your two subs? Have you "time aligned" the two subs to one another? This is most often done using a miniDSP unit. However, if your subs have their own volume knobs (most do) and variable phase knobs (many do) then it is possible you did both of these steps without a miniDSP.
> 
> Neither of the two steps above can be done with ARC on most Anthem units.
> 
> Then, figuring out the best crossover settings, and the distance setting for the summed subs, would be the next step. (Note that "distance setting" has nothing to do with physical distance. It's really more of a way to phase align the subs -- summed in a group already -- with the mains.) I'm inferring that you haven't done these two steps based on the discussion.
> 
> ---
> 
> In short, @fattire is right, and even more right since issues around 100 hz aren't going to be significantly impacted by more room treatment unless it is tuned bass traps....and that wouldn't be the first place to start, but, rather, something to consider is subwoofer setup and integration doesn't solve things.
> 
> ---
> 
> The good news is you have two subs and you know how to use REW. Those pieces are actually the biggest stumbling blocks for most people!
> 
> 
> 
> (PS chances are good that the placement of your subs is going to be workable.)


Thanks for this. I am not offended in the least and am grateful for your assistance, thank you! FYI I have an anthem MRX 1140 which is their newest big AVR.

Both subs are DIY without built-in crossovers or filters and are identical.
I am using a inuke-6000 no DSP model to power them. 

I have matched the gain knobs. *However ARC wants one to be louder than the other (+7 vs +4.5) and I let it do this. *One subwoofer has a ton of insulation around it perhaps that explains some.

*I have NOT time aligned the subs. *I don't think I have phase knobs on the inuke.

In terms of settings I can change the crossover frequency, low frequency extension, minimum correction frequency, speaker levels, *distance of each sub separately* (is this what you're getting at? if so, what do I put?), *phase frequency* (seems relevant?), *phase in degrees between 1 and 180, and polarity (inversed vs normal).*


----------



## nathan_h

Interesting. I think you MIGHT have all the controls you need in order to gain match (or level match) the subs and "time align" them (typically done by adjust the individual delay/distance/phase of each sub until their summed behavior is ideal).

HTGurus has a slightly rambling, very detailed video about how to do this. He uses the miniDSP to adjust things, but you can mentally translate his instructions (like he is adjusting individual distance settings for each sub in the miniDSP but you could do this with the other controls you have; I don't know how the 1140 works but it claims to be able to set the distance for each sub independently which is a way to time align/phase align the subs).

Athough his thread is not very active, it contains the video and some discussion and this might be a good place to start.

REW subwoofer alignment Video using MiniDSP complete walk through!

NOTE that he spends a lot of time explaining things you already understand (like how to use REW) so if it gets tedious you can probably fast forward through much of that.


----------



## rec head

@Snoochers I would try a crossover around 120Hz just to see what it looks like. I have tried moving my L/R all over my room to get their response smoother down to 80Hz and they just won't do it anywhere remotely acceptable. I run high crossovers and it works pretty well. My subs are in the front corners and there is no localization.


----------



## Snoochers

rec head said:


> @Snoochers I would try a crossover around 120Hz just to see what it looks like. I have tried moving my L/R all over my room to get their response smoother down to 80Hz and they just won't do it anywhere remotely acceptable. I run high crossovers and it works pretty well. My subs are in the front corners and there is no localization.


thanks for this. I have tried moving the crossover around without much luck. I think ARC also tries to set it up to its own liking but it hasn't worked. I'm not sure how phase works into this but I'll investigate!


----------



## nathan_h

Moving the crossover around can help BUT in my experience only after getting the two subs gain (or level) matched, and time aligned with one another, and after getting the distance setting (acoustic measurement, not really distance) dialed in for the subs playing as a single unit.


----------



## Snoochers

I went into the theatre to calibrate my subs after doing some research and I ran a baseline measurement (below). This looks pretty good and I don't see the issue I had before... very odd. This is with 1/6 smoothing. Maybe I didn't have my mic calibrated properly last time or something? Comments on this curve?


----------



## nathan_h

That looks very nice. If you want to see how they sound to your ears, REW has a choice for "psychoacoustic smoothing" that takes into account the differences in our perception of sound at different frequencies. I find that matches the real world better than the traditional kinds of smoothing like "1/6th octave" etc.


----------



## nathan_h

Another useful overview of room acoustics that touches on how treatments play into making a room sound good. The first half is about some of the key ways to understand how speakers behave in rooms. The second half is about how, once you get a speaker that behaves well, how to get them to sound as good as they can in the room (where acoustic treatments play a key role).

Fun quote (paraphrased): setup and room treatment can double the quality of the sound, for a fraction of the price of upgrading speakers and other gear.

Note this is not as in depth as the discussions Tony did with AVProEdge which are available on YouTube, or even the ones he did with Audiohilcs. 

I wish they did just ten minutes on sound power and the rest on measuring and treating a room -- but it’s good info, none the less.

Hopefully they will do the promised follow up ..... but this took place more than six months ago, so I'm guessing there is no part two forthcoming.


----------



## Sitron_NO

*A bit of background: *I am about to make myself some absorption panels and bass traps, and have everything ready, except for what fabric/textile to use. Reading about fabrics, there are some recommendations, but they are all US based. So I have not the option to buy those (not without a lot of hassle), so I want to buy locally (here in Norway).
Looking the the companies making fabric, none lists "Acoustic transparent" as a feature. But for some fabrics, they list "Sound absorbent" as a feature, as in "Sound absorption ISO 354:2003 - Class C".
This sent me to this YT video explaining about this test/standard, and what is means to get a "Class C". By digging a bit deeper, I found a fabric from Ludvig Svensson which features _"top-class sound absorption" _according to their webpage. Lucky, they provide the document from the lab-test, so we can see what they have done - and why this fabric got a "Class A" in regards to ISO 354.

*My question:* Can I use this ISO 354 and it's classification when I am buying fabric for my absorption panels and bass traps? Or is it like comparing apples and oranges?
If I can use it, I assume a "Class A" is the best option, since it will absorb sound, and that is exactly what the point of the absorption panel in the first place?
And am I correct in assuming that a "Class E" can be both 100% reflective *or* 100% transparent according to the test preformed?


----------



## nathan_h

Sitron_NO said:


> *A bit of background: *I am about to make myself some absorption panels and bass traps, and have everything ready, except for what fabric/textile to use. Reading about fabrics, there are some recommendations, but they are all US based. So I have not the option to buy those (not without a lot of hassle), so I want to buy locally (here in Norway).
> Looking the the companies making fabric, none lists "Acoustic transparent" as a feature. But for some fabrics, they list "Sound absorbent" as a feature, as in "Sound absorption ISO 354:2003 - Class C".
> This sent me to this YT video explaining about this test/standard, and what is means to get a "Class C". By digging a bit deeper, I found a fabric from Ludvig Svensson which features _"top-class sound absorption" _according to their webpage. Lucky, they provide the document from the lab-test, so we can see what they have done - and why this fabric got a "Class A" in regards to ISO 354.
> 
> *My question:* Can I use this ISO 354 and it's classification when I am buying fabric for my absorption panels and bass traps? Or is it like comparing apples and oranges?
> If I can use it, I assume a "Class A" is the best option, since it will absorb sound, and that is exactly what the point of the absorption panel in the first place?
> And am I correct in assuming that a "Class E" can be both 100% reflective *or* 100% transparent according to the test preformed?


I don’t know the specific answer to your question.

This is a European blog that talks about panels from time to time and might have useful local info.




__





Acoustics Insider


Acoustic treatment techniques for audio professionals, but without all the voodoo.




www.acousticsinsider.com





Also I think the ”blow test” (testing whether you can easily breathe through it) is not a bad starting point for trying out random fabrics for panels.


----------



## DarinS

PixelPusher15 said:


> Ah, yeah. I've looked at that before. My seating position is at 10.5' so I'm pretty much right there at the 3/4 length. No measurement I've done around the MLP has ever not shown this dip. Moving my couch is kinda not an option right now. I moved it forward to "increase" the screen size that I wanted but also to increase the angle of the front L/R speaker for better soundstaging. I really like it's position right now. I also don't think moving it back a foot would do much either. I saw the null there as well.
> 
> Would treating the back wall with any of my options help?


Take this with grain of salt as certainly not a pro, but if you sit in a null you’ll be hosed no matter what you do with traps. Buy a second sub to smooth that out. Play around with REW and get them aligned with positive summation. Lots of great videos but I like Home Theater Gurus on YouTube. Easy to understand and not super in depth. I bet a second sub is your answer. In my room it took one sub up front and one on back wall but worked like a charm.

also, agree with post above…may need to move your couch to get best response. When I designed my room, I chose my seat position based on REW sims. 

anyhow, hope you figure it out
Darin


----------



## PixelPusher15

DarinS said:


> Take this with grain of salt as certainly not a pro, but if you sit in a null you’ll be hosed no matter what you do with traps. Buy a second sub to smooth that out. Play around with REW and get them aligned with positive summation. Lots of great videos but I like Home Theater Gurus on YouTube. Easy to understand and not super in depth. I bet a second sub is your answer. In my room it took one sub up front and one on back wall but worked like a charm.
> 
> also, agree with post above…may need to move your couch to get best response. When I designed my room, I chose my seat position based on REW sims.
> 
> anyhow, hope you figure it out
> Darin


Thanks. That is pretty much my plan at this point...add a second sub. Since I have a 2ch pro amp and will go the DIY route for the second sub it seems like the most economical route too.


----------



## IMostlyPreferOLED

PixelPusher15 said:


> Thanks. That is pretty much my plan at this point...add a second sub. Since I have a 2ch pro amp and will go the DIY route for the second sub it seems like the most economical route too.


I have a very small HT and am not bass obsessed (ie, I don’t watch effects laden videos). I had sufficient bass and it was relatively well balanced in the room, but I added a second sub that closely matched my existing sub (discontinued and I don’t like to buy used). Much smoother and I recommend it.


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## dwander

I’m thinking of adding a few things to my room: corner bass traps, and ceiling panels between the center channel and the seats. I have a couple questions. My front stage is surrounded by velvet wrapped panels, and I’d place corner traps behind them. I’m just not sure if the sound travels through the velvet or not to make it worthwhile. 

For the ceiling panels, I have to see what thickness I can get away with. My screen is pretty high to the ceiling and it could interfere. If I can fit 4” panels is there a recommended way to flush mount to the ceiling without seeing any brackets?


----------



## carp

dwander said:


> I’m thinking of adding a few things to my room: corner bass traps, and ceiling panels between the center channel and the seats. I have a couple questions. My front stage is surrounded by velvet wrapped panels, and I’d place corner traps behind them. I’m just not sure if the sound travels through the velvet or not to make it worthwhile.
> 
> For the ceiling panels, I have to see what thickness I can get away with. My screen is pretty high to the ceiling and it could interfere. If I can fit 4” panels is there a recommended way to flush mount to the ceiling without seeing any brackets?


You could use french cleats. Use 2 of them and slide the panel in place. It's not cheap since you would need 2 per panel and you would have to be very exact in your placement of them but it's doable and it's the only thing I can think of. 









OOK 60 lb. French Cleat Picture Hanger with Wall Dog Mounting Screws Kit (7-Piece) 55310 - The Home Depot






www.homedepot.com


----------



## dwander

carp said:


> You could use french cleats. Use 2 of them and slide the panel in place. It's not cheap since you would need 2 per panel and you would have to be very exact in your placement of them but it's doable and it's the only thing I can think of.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> OOK 60 lb. French Cleat Picture Hanger with Wall Dog Mounting Screws Kit (7-Piece) 55310 - The Home Depot
> 
> 
> 
> 
> 
> 
> www.homedepot.com


I wasn’t sure if that would work for ceiling mount since it kind of relies on gravity to hold in place. But if it works I can do that.


----------



## nathan_h

carp said:


> You could use french cleats. Use 2 of them and slide the panel in place. It's not cheap since you would need 2 per panel and you would have to be very exact in your placement of them but it's doable and it's the only thing I can think of.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> OOK 60 lb. French Cleat Picture Hanger with Wall Dog Mounting Screws Kit (7-Piece) 55310 - The Home Depot
> 
> 
> 
> 
> 
> 
> www.homedepot.com





dwander said:


> I wasn’t sure if that would work for ceiling mount since it kind of relies on gravity to hold in place. But if it works I can do that.


This is how my ceiling panels are connected. In the past I used eye hooks and they hung down six inches and that was great for capturing deeper frequencies but in my current room (and apparently in yours) there isn't space for that air gap, so French cleats was my answer.

There are some diagrams of them in action on the Acoustimac web site (which is there I got my ceiling panels).


----------



## nathan_h

dwander said:


> I’m just not sure if the sound travels through the velvet or not to make it worthwhile.


For bass traps, velvet should not be a problem. Some kinds of velvet are too non transparent for high frequencies to travel through them easily but it is possible to cover a bass trap in something as non porous as cardboard and still have an effective bass trap.


----------



## dwander

nathan_h said:


> For bass traps, velvet should not be a problem. Some kinds of velvet are too non transparent for high frequencies to travel through them easily but it is possible to cover a bass trap in something as non porous as cardboard and still have an effective bass trap.


Thanks for the answers. Going move forward on both.


----------



## chych7

Sitron_NO said:


> *A bit of background: *I am about to make myself some absorption panels and bass traps, and have everything ready, except for what fabric/textile to use. Reading about fabrics, there are some recommendations, but they are all US based. So I have not the option to buy those (not without a lot of hassle), so I want to buy locally (here in Norway).
> Looking the the companies making fabric, none lists "Acoustic transparent" as a feature. But for some fabrics, they list "Sound absorbent" as a feature, as in "Sound absorption ISO 354:2003 - Class C".
> This sent me to this YT video explaining about this test/standard, and what is means to get a "Class C". By digging a bit deeper, I found a fabric from Ludvig Svensson which features _"top-class sound absorption" _according to their webpage. Lucky, they provide the document from the lab-test, so we can see what they have done - and why this fabric got a "Class A" in regards to ISO 354.
> 
> *My question:* Can I use this ISO 354 and it's classification when I am buying fabric for my absorption panels and bass traps? Or is it like comparing apples and oranges?
> If I can use it, I assume a "Class A" is the best option, since it will absorb sound, and that is exactly what the point of the absorption panel in the first place?
> And am I correct in assuming that a "Class E" can be both 100% reflective *or* 100% transparent according to the test preformed?



Any knit fabric will be fine (that you can breathe through), you don't need to overspend or overthink it. I went with some cheaper knit fabric from the fabric store, instead of acoustic cloth. I took some measurements against some speaker grille cloth. There was only a 1-2 dB attenuation at >5 kHz, which is negligible. The higher frequencies don't really need much absorption anyway, and bass frequencies go through solid walls so they won't care either way.


----------



## Frohlich

squared80 said:


> Here ya go...


Wanted to say thank you to the intel on this thread. I had seen this video before and it resonated with me...I also like how Grimani shows the visual of how you could lay out a room. Helped it sink in for me. So I ordered some more Vicoustic diffusion and absorption treatments and layered them in this week at the first reflection point and the rear of the room. Room sounds better than ever


----------



## carp

Nice Frolich!

I did something similar recently. I did kind a combo between what's on that video and this room: Home Theater of the Month: The Event Horizon
also taking a lot of advice from @harrisu .

First reflection points on both side walls, same with first reflection point on the ceiling:









I covered all the checkerboard diffusion/absorption panels with AT velvet from hobby lobby. You can see in this pic I have a few diffusion panels directly above my front row, I plan on adding more.









Since these pictures were taken I have swapped out the 2 2'x2' absorption panels on the rear wall with the diffusion panels that are in front of the side surrounds, and I like it better that way.








Frolich - I see you didn't take the advice in the video that talked about not having matched treatments, for example if you have a diffusion panel on the left wall then there should be absorption directly across from it.

I just couldn't do that either... my MLP seat is dead center and it would drive me nuts not to have the treatments the same on each side of me. I suppose I'll try it but I'm really liking the results as is. I do think I'll get more of the skyline diffusor treatments for the rear part of the room on the ceiling and maybe some more absorption for that area of the ceiling too, but I'm going to live with this for awhile since I'm liking it.


----------



## kiddbios

Good morning, all. I am on my home theater room treatment journey, and am looking for some advice. I have 9 bed layer speakers, 6 top speakers, 4 height speakers (2 front, 2 back), and 4 subs. Speakers are all Revel, 426BE, 328BE, M105s for surrounds, C763L for tops and MX55 for heights. Subs are JL Audio E-112. The CC and 2 subs are mounted on a cabinet behind the screen at ear height. The other 2 subs are in each of the back corners.

My room is 26'L x 15'W x 9' H. I currently have 2" panels made from OC-703 that are suspended 2" and cover the entire drywall ceiling. The back wall is covered in panels with 1.5" rockwool. There are 2" OC-703 panels on each sidewall behind the side surrounds that measure 6' x 4'. There are 2 5'W x 7'H windows on one side of the room with corresponding arched openings on the opposite side of the room. These have fabric shutters that close to block out any ambient light (no doors). The windows have heavy curtains.

I'm using a Storm Audio ISP-MK2 for my pre-pro and a combination of Monolith and Emotiva amplifiers. Each channel has at least 200 dedicated watts of amplification. I have a 126" Dreamscreen v7 acoustically transparent weaved screen. 

The screen is mounted to custom cabinets above and below (pictured below). This creates space to store all of the electronics, but it also creates a cavity behind the speakers. I was getting some fairly large dips in REW and Dirac in the 70-80Hz range and again in 300-400Hz range. Right now I feel there is too much bass in the room, so it sounds slightly slow and imprecise, and also lacks impact. 

My goal is to tighten up the bass, improve the "punch" of the front soundstage, and improve imaging, especially that of the surround sound field. 

My belief is that currently there is reflectivity and standing waves due to the cavity behind the screen and the hard surfaces therein. There is the top of the bottom cabinet, the bottom of the upper cabinet and the 4' wide double doors that are about 3 feet behind the CC. If I open those doors, the measurements (especially that of the CC) improve substantially. I do have 1.5" rockwool panels on the doors and along the back and side walls within the cavity.

My thinking is to stack OC-703 in both of the front corners from the floor to the bottom of the cabinet. I was then going to build an 8" thick box of OC703 around the CC and 2 front subs, which would enclose the top, bottom and side areas behind the screen. So basically imagine if you had a rectangular cube made of insulation with the front side removed, and pushed up against the back of the screen. I'll make it all pretty with some panels made with Guilford of Maine fabric. I'll then add some bass traps to the back corners to hopefully tame any excess bass that is building up there and possibly (probably) some additional 2" panels on the side walls to further reduce any high frequency reflections.

Any feedback is greatly appreciated.


----------



## nathan_h

kiddbios said:


> Good morning, all. I am on my home theater room treatment journey, and am looking for some advice. I have 9 bed layer speakers, 6 top speakers, 4 height speakers (2 front, 2 back), and 4 subs. Speakers are all Revel, 426BE, 328BE, M105s for surrounds, C763L for tops and MX55 for heights. Subs are JL Audio E-112. The CC and 2 subs are mounted on a cabinet behind the screen at ear height. The other 2 subs are in each of the back corners.
> 
> My room is 26'L x 15'W x 9' H. I currently have 2" panels made from OC-703 that are suspended 2" and cover the entire drywall ceiling. The back wall is covered in panels with 1.5" rockwool. There are 2" OC-703 panels on each sidewall behind the side surrounds that measure 6' x 4'. There are 2 5'W x 7'H windows on one side of the room with corresponding arched openings on the opposite side of the room. These have fabric shutters that close to block out any ambient light (no doors). The windows have heavy curtains.
> 
> I'm using a Storm Audio ISP-MK2 for my pre-pro and a combination of Monolith and Emotiva amplifiers. Each channel has at least 200 dedicated watts of amplification. I have a 126" Dreamscreen v7 acoustically transparent weaved screen.
> 
> The screen is mounted to custom cabinets above and below (pictured below). This creates space to store all of the electronics, but it also creates a cavity behind the speakers. I was getting some fairly large dips in REW and Dirac in the 70-80Hz range and again in 300-400Hz range. Right now I feel there is too much bass in the room, so it sounds slightly slow and imprecise, and also lacks impact.
> 
> My goal is to tighten up the bass, improve the "punch" of the front soundstage, and improve imaging, especially that of the surround sound field.
> 
> My belief is that currently there is reflectivity and standing waves due to the cavity behind the screen and the hard surfaces therein. There is the top of the bottom cabinet, the bottom of the upper cabinet and the 4' wide double doors that are about 3 feet behind the CC. If I open those doors, the measurements (especially that of the CC) improve substantially. I do have 1.5" rockwool panels on the doors and along the back and side walls within the cavity.
> 
> My thinking is to stack OC-703 in both of the front corners from the floor to the bottom of the cabinet. I was then going to build an 8" thick box of OC703 around the CC and 2 front subs, which would enclose the top, bottom and side areas behind the screen. So basically imagine if you had a rectangular cube made of insulation with the front side removed, and pushed up against the back of the screen. I'll make it all pretty with some panels made with Guilford of Maine fabric. I'll then add some bass traps to the back corners to hopefully tame any excess bass that is building up there and possibly (probably) some additional 2" panels on the side walls to further reduce any high frequency reflections.
> 
> Any feedback is greatly appreciated.
> 
> View attachment 3236829
> View attachment 3236835


Can you post your REW graphs? The frequency sweeps (ALL SPL) and the RT60 (not RT60 DECAY but just RT60) graphs in particular might provide some objective clues.

From your description, I would hypothesize:

1. You feel like you have too much bass because you have too much high frequency absorption & because the bass is not even and consistent.
2. You don't have room to trap bass with passive means (ie, you cannot fit a six foot bass trap in there) so if analysis indicated bass trapping is needed, you may need membrane/tuned/tympanic or similar devices. BUT I DOUBT IT, because:
3. Two of your subs are in the wrong locations. The rear subs are great but the front subs should ALSO be directly in the front corners. Years of research has found that this is almost the best layout in a rectangular sealed room. (The best is mid point of each wall, but that is awkward and requires more output for the same impact.)
4. Bass management. I'm not intimately familiar with the bass management features of your processor. I think it can do independent distance, phase, and levels for each sub. But I don't know whether those have been dialed in (and they will change, anyway, once the front subs are moved to the better locations).
(5. I'm assuming all speakers are set to SMALL and crossed over at 80 h or higher to the subs. If not, that's another contributing issue.)


----------



## kiddbios

nathan_h said:


> Can you post your REW graphs? The frequency sweeps (ALL SPL) and the RT60 (not RT60 DECAY but just RT60) graphs in particular might provide some objective clues.
> 
> From your description, I would hypothesize:
> 
> 1. You feel like you have too much bass because you have too much high frequency absorption & because the bass is not even and consistent.
> 2. You don't have room to trap bass with passive means (ie, you cannot fit a six foot bass trap in there) so if analysis indicated bass trapping is needed, you may need membrane/tuned/tympanic or similar devices. BUT I DOUBT IT, because:
> 3. Two of your subs are in the wrong locations. The rear subs are great but the front subs should ALSO be directly in the front corners. Years of research has found that this is almost the best layout in a rectangular sealed room. (The best is mid point of each wall, but that is awkward and requires more output for the same impact.)
> 4. Bass management. I'm not intimately familiar with the bass management features of your processor. I think it can do independent distance, phase, and levels for each sub. But I don't know whether those have been dialed in (and they will change, anyway, once the front subs are moved to the better locations).
> (5. I'm assuming all speakers are set to SMALL and crossed over at 80 h or higher to the subs. If not, that's another contributing issue.)


Thank you!

I'll get you the REW graphs. What smoothing would you like me to use? Would you like me to measure every speaker or just the LCR and subs? Just the MLP, or should I measure at different spots around the room?

I use Dirac Live Bass Management. Each sub is on its own individual input, measured independently, and then integrated with the whole. Crossover is set at 80Hz on the LCR, 90Hz on the surrounds and 110Hz for the tops and heights.

I don't have enough width between the screen and the side wall to put the subs on the floor in the corners, unless they're behind the left and right mains.


----------



## nathan_h

kiddbios said:


> Thank you!
> 
> I'll get you the REW graphs. What smoothing would you like me to use? Would you like me to measure every speaker or just the LCR and subs? Just the MLP, or should I measure at different spots around the room?
> 
> I use Dirac Live Bass Management. Each sub is on its own individual input, measured independently, and then integrated with the whole. Crossover is set at 80Hz on the LCR, 90Hz on the surrounds and 110Hz for the tops and heights.
> 
> I don't have enough width between the screen and the side wall to put the subs on the floor in the corners, unless they're behind the left and right mains.


I'm a fan of REW's psychoacoustic smoothing. Since what you are chasing is better bass, I would guess that seeing a full range sweep (sub plus speaker) from you MLP for you subs plus one speaker (left right or center) maybe show enough information to get feedback from folks here.

I've been told Dirac bass management can "do it all" (level match and time align all the subs, and then EQ them as one mono source) which should be enough.

I don't quite know what being behind the mains means for the front subs. Does that really put them in the corners? That should be fine for them to be behind the mains, in that case. Maybe a photo of the space showing the corner and where you could put the subs (ie, don't move them yet if that's a hassle) would help illustrate it.

In theory (and usually in practice) four corner subs should give you an excellent acoustic environment for getting great bass once they are configured well and then eq-ed.....without a bunch of bass trapping. (I'm not saying bass trapping is useless, but in many ways, four subs interact in ways to mitigate room problems more effectively than trapping in many cases.)


----------



## anjunadeep

nathan_h said:


> In theory (and usually in practice) four corner subs should give you an excellent acoustic environment for getting great bass once they are configured well and then eq-ed.....without a bunch of bass trapping. (I'm not saying bass trapping is useless, but in many ways, four subs interact in ways to mitigate room problems more effectively than trapping in many cases.)


Didn't the Todd Welti Harman Papers end up basically recommending 1/4 wall placements (front and rear walls) for four subs for the best response? Or was it just four corners?


----------



## kiddbios

nathan_h said:


> I'm a fan of REW's psychoacoustic smoothing. Since what you are chasing is better bass, I would guess that seeing a full range sweep (sub plus speaker) from you MLP for you subs plus one speaker (left right or center) maybe show enough information to get feedback from folks here.
> 
> I've been told Dirac bass management can "do it all" (level match and time align all the subs, and then EQ them as one mono source) which should be enough.
> 
> I don't quite know what being behind the mains means for the front subs. Does that really put them in the corners? That should be fine for them to be behind the mains, in that case. Maybe a photo of the space showing the corner and where you could put the subs (ie, don't move them yet if that's a hassle) would help illustrate it.
> 
> In theory (and usually in practice) four corner subs should give you an excellent acoustic environment for getting great bass once they are configured well and then eq-ed.....without a bunch of bass trapping. (I'm not saying bass trapping is useless, but in many ways, four subs interact in ways to mitigate room problems more effectively than trapping in many cases.)


Please take a look at my post #13,260 on the previous page. On the "Front of room.jpg" picture at the bottom, you can see the corner area behind the speakers.


----------



## nathan_h

anjunadeep said:


> Didn't the Todd Welti Harman Papers end up basically recommending 1/4 wall placements (front and rear walls) for four subs for the best response? Or was it just four corners?


1. midpoint of the four walls was best for response EXCEPT not best for output
2. four corners was slightly less good for consistent response but much better for output

two subs was almost as good when placed well



https://www.harman.com/documents/multsubs_0.pdf












--

Those are not the only ways to make things work, of course. Of note is that if one has only a single row of seating, you can get away with both subs on the front or rear wall, at the 1/4 and 3/4 width points, but may have to move the row of seating forward or back because you have let the modes run wild length wise. But for a larger seating area or more freedom of seating placement, the four sub solution is the easy one.


----------



## nathan_h

kiddbios said:


> Please take a look at my post #13,260 on the previous page. On the "Front of room.jpg" picture at the bottom, you can see the corner area behind the speakers.


Yeah I don't see why you can't put the subs directly in the corners.

(I do also now see that the left wall is not contiguous but there is a bump out of some sort. If that is a large or open space, then you don't really have a rectangular room. It's still all doable. but make take more experimenting.)


----------



## kiddbios

nathan_h said:


> Yeah I don't see why you can't put the subs directly in the corners.
> 
> (I do also now see that the left wall is not contiguous but there is a bump out of some sort. If that is a large or open space, then you don't really have a rectangular room. It's still all doable. but make take more experimenting.)


The room is rectangular. That opening is an archway. I have a motorized cover that closes and seals the room. 

Would you put the subs in the corners and face them straight forward?


----------



## nathan_h

Ah okay as long as there is a door there and not just a curtain it should be easier ie more predictable.

Sort of doesn’t matter whether they face into the room or towards each other, though ideally you’d mimic and mirror their direction (whatever you choose) in the rear as well.


----------



## anjunadeep

nathan_h said:


> 1. midpoint of the four walls was best for response EXCEPT not best for output
> 2. four corners was slightly less good for consistent response but much better for output
> 
> two subs was almost as good when placed well
> 
> 
> 
> https://www.harman.com/documents/multsubs_0.pdf
> 
> 
> 
> View attachment 3237170
> 
> 
> --
> 
> Those are not the only ways to make things work, of course. Of note is that if one has only a single row of seating, you can get away with both subs on the front or rear wall, at the 1/4 and 3/4 width points, but may have to move the row of seating forward or back because you have let the modes run wild length wise. But for a larger seating area or more freedom of seating placement, the four sub solution is the easy one.


Ah okay, yeah I was getting the quarter placement with four subs from this interview:










I imagine the 1/4 placement is less efficient output wise still.. I'll have to go back and listen to this interview again.


----------



## nathan_h

That was a fun interview, especially how he had to break it to the AVRant guys (who I quite enjoy and have listened to for years, since well before Rob's time, back when Tom had the first of two female co hosts) that the diagonal corner recommendation they rely on was actually not in the top tier of recommendations. 

But the thing that stuck with me was how much Welti found the REW room modeling feature to be a great way to predict real world results with a high degree of confidence.

I forget what those labels mean but yes it appears there is a benefit to that 1/4 placement of four, as well.


----------



## sdurani

anjunadeep said:


> I imagine the 1/4 placement is less efficient output wise still.. I'll have to go back and listen to this interview again.


Quarter point placement gets rid of the first 3 modes while corner placement gets rid of the odd numbered modes (1st, 3rd). From Welti's paper, you can see that room modes have polarity.








Placing subs in the corners will cancel odd numbered modes (e.g., 1st axial mode) because they will be driven by opposing polarities. But that doesn't happen with even numbered modes (e.g., 2nd axial mode) because the subs are driving the mode with the same polarity so it just exaggerates everything (louder peaks, quieter dips). In small residential-sized rooms, a couple of the listeners could end up at or near the nulls while the listener in the main listening position is sitting at a peak location. So much for seat-to-seat consistency. CEDIA best practices recommend staying at least 1.5' from nulls.

How does Welti reconcile this problem with his corner placement recommendation? He uses a 20' x 24' test room and imagines 16 listeners in a 6' x 6' listening area (no joke). The quarter points of his test room fall on a 10' x 12' rectangle, so his 6' x 6' listening area is well clear of the nulls that result from corner placement.









IF the size of his test room *vs* the listening area doesn't come close to your room *vs* listening area, you might want to think carefully about blindly accepting the corner placement recommendation. With quarter point placement, you're cancelling the first 3 modes (above which you're typically out of the subwoofer range), so you no longer have to deal with the nulls from the 2nd axial mode.


----------



## nathan_h

sdurani said:


> Quarter point placement gets rid of the first 3 modes while corner placement gets rid of the odd numbered modes (1st, 3rd). From Welti's paper, you can see that room modes have polarity.
> View attachment 3237294
> 
> Placing subs in the corners will cancel odd numbered modes (e.g., 1st axial mode) because they will be driven by opposing polarities. But that doesn't happen with even numbered modes (e.g., 2nd axial mode) because the subs are driving the mode with the same polarity so it just exaggerates everything (louder peaks, quieter dips). In small residential-sized rooms, a couple of the listeners could end up at or near the nulls while the listener in the main listening position is sitting at a peak location. So much for seat-to-seat consistency. CEDIA best practices recommend staying at least 1.5' from nulls.
> 
> How does Welti reconcile this problem with his corner placement recommendation? He uses a 20' x 24' test room and imagines 16 listeners in a 6' x 6' listening area (no joke). The quarter points of his test room fall on a 10' x 12' rectangle, so his 6' x 6' listening area is well clear of the nulls that result from corner placement.
> View attachment 3237300
> 
> 
> IF the size of his test room *vs* the listening area doesn't come close to your room *vs* listening area, you might want to think carefully about blindly accepting the corner placement recommendation. With quarter point placement, you're cancelling the first 3 modes (above which you're typically out of the subwoofer range), so you no longer have to deal with the nulls from the 2nd axial mode.


Agree. That is why he didn't stop at one physical room and one set of assumptions.

For example, he created these maps (this is not the complete list) for many other sized rooms. 



















Once he confirmed in real rooms that his math was working, it was "easy" to model many other configurations and room sizes.

And of course one isn't limited to the handful of optimal positions and sizes in his paper. This is particularly important in terms of seating location, as you point out. What to do? Welti recommends REW.

Based on this science, the REW room tool (the modeling part not the measurement part) becomes the ultimate way to get a handle on particular situations in the sense that any possible set of dimensions, subwoofer locations, etc can be modeled, based on this science. 

Nothing replaces actually measuring and adjusting in the real world of course, but these tools can help to narrow the range of things to try from thousands of combinations to just a handful. And REW is what he uses when trying out new ideas before going to the expense of more complicated and time consuming steps.


----------



## anjunadeep

sdurani said:


> Quarter point placement gets rid of the first 3 modes while corner placement gets rid of the odd numbered modes (1st, 3rd). From Welti's paper, you can see that room modes have polarity.
> View attachment 3237294
> 
> Placing subs in the corners will cancel odd numbered modes (e.g., 1st axial mode) because they will be driven by opposing polarities. But that doesn't happen with even numbered modes (e.g., 2nd axial mode) because the subs are driving the mode with the same polarity so it just exaggerates everything (louder peaks, quieter dips). In small residential-sized rooms, a couple of the listeners could end up at or near the nulls while the listener in the main listening position is sitting at a peak location. So much for seat-to-seat consistency. CEDIA best practices recommend staying at least 1.5' from nulls.
> 
> How does Welti reconcile this problem with his corner placement recommendation? He uses a 20' x 24' test room and imagines 16 listeners in a 6' x 6' listening area (no joke). The quarter points of his test room fall on a 10' x 12' rectangle, so his 6' x 6' listening area is well clear of the nulls that result from corner placement.
> View attachment 3237300
> 
> 
> IF the size of his test room *vs* the listening area doesn't come close to your room *vs* listening area, you might want to think carefully about blindly accepting the corner placement recommendation. With quarter point placement, you're cancelling the first 3 modes (above which you're typically out of the subwoofer range), so you no longer have to deal with the nulls from the 2nd axial mode.


Yeah, I did a bit of a deep dive a while back and came up with that in most smaller rooms having four subwoofers about 1/4 away from each wall seems to work well. Now I'm getting toward the point where I need to install some wires and when I model my room in REW the result isn't great... It could be I'm not setting the delays correctly, but I figure the rear subs should be about 4ms off from the front based on the distances and fiddling around haven't found some combo that fixes things.

1/4 placement:










Corners:










So I donno...


----------



## nathan_h

anjunadeep said:


> Yeah, I did a bit of a deep dive a while back and came up with that in most smaller rooms having four subwoofers about 1/4 away from each wall seems to work well. Now I'm getting toward the point where I need to install some wires and when I model my room in REW the result isn't great... It could be I'm not setting the delays correctly, but I figure the rear subs should be about 4ms off from the front based on the distances and fiddling around haven't found some combo that fixes things.
> 
> 1/4 placement:
> 
> View attachment 3237332
> 
> 
> Corners:
> View attachment 3237337
> 
> 
> 
> So I donno...


Remember you won’t see a flat curve.

What you want is a curve that looks the same across your seats* so when you eq it you get the same corrections to “flat” (probably really a house curve if you are like most of us) across the seats.

(*ideally with peaks and no wide dips in the subwoofer region since peaks are easier to tame)


----------



## anjunadeep

nathan_h said:


> Remember you won’t see a flat curve.
> 
> What you want is a curve that looks the same across your seats* so when you eq it you get the same corrections to “flat” (probably really a house curve if you are like most of us) across the seats.
> 
> (*ideally with peaks and no wide dips in the subwoofer region since peaks are easier to tame)


I know, and I'm only dealing with one row which makes things easier, but sure seems like I need a lot of boost around 50Hz. Moving things around a bit doesn't help much, which I think actually my 9' 8" ceiling is contributing... I was all happy to have a reasonably high ceiling for Atmos lol. I still think I'm setting the room simulator wrong somehow... (hoping?)


----------



## sdurani

nathan_h said:


> For example, he created these maps (this is not the complete list) for many other sized rooms.


The smallest room is 4m x 4m but he still uses a 2m x 2m seating area to stay inside the quarter point nulls ("quatrals" as he calls them). Does anyone else think that 6' x 6' is unrealistic for 16 seats? 

Anyway, my only point is that quarter point placement offers mode cancelling advantages that 4 corner (or 4 midpoint) placement does not. You lose some overall level (MOL) without the corner placement boost in exchange for better spatial variance (MSV) by avoiding quarter point nulls.


----------



## sdurani

anjunadeep said:


> 1/4 placement:


Does that simulation include the bass from the 2 speakers near the corners of the room?


----------



## nathan_h

sdurani said:


> The smallest room is 4m x 4m but he still uses a 2m x 2m seating area to stay inside the quarter point nulls ("quatrals" as he calls them). Does anyone else think that 6' x 6' is unrealistic for 16 seats?
> 
> Anyway, my only point is that quarter point placement offers mode cancelling advantages that 4 corner (or 4 midpoint) placement does not. You lose some overall level (MOL) without the corner placement boost in exchange for better spatial variance (MSV) by avoiding quarter point nulls.


I'm agreeing with you. His rooms used in the original models, and the physical testing, may not reflect real rooms that many of us have. But based on real rooms confirming his math, one can THEN use his math for many different sized rooms and many different seating locations that more accurately reflect real rooms.

To get back to the OP's post, the path of least resistance was to move his front subs to the front corners, since he has room and since his read subs are in the rear corners already.

It may not be the ultimate placement, but seeing how the listening position measures once he does that would be a useful step, imo, before making even more changes to subwoofer layout in this room.


----------



## nathan_h

anjunadeep said:


> I know, and I'm only dealing with one row which makes things easier, but sure seems like I need a lot of boost around 50Hz. Moving things around a bit doesn't help much, which I think actually my 9' 8" ceiling is contributing... I was all happy to have a reasonably high ceiling for Atmos lol. I still think I'm setting the room simulator wrong somehow... (hoping?)



First, get rid of the delay. For this step, it confuses things. Leave the subs in the corners for now.

Second, move the listening head position up and down. Does that change the 50hz dip?

Move the listener head forward a few feet and backward a few feet and sideways a few feet. Does that change it?

If you are dealing with a room height mode, then changing the listener head position up and down can help..or at least should change that dip.

If, on the other hand, horizontal movement changes the dip, then you are dealing with a mode in a different direction.

(If you are dealing with a height mode, and you cannot realistically move the listening head to a better spot in terms of height, that a small riser might help OR you can consider moving the subs off the floor, which will have the same kind of impact to where vertical modes fall as moving the listener head position did.)


----------



## anjunadeep

sdurani said:


> Does that simulation include the bass from the 2 speakers near the corners of the room?
> View attachment 3237356


It has the L and R in there with a -3 of 80Hz. If I remove the L and R, the response doesn't improve anyways. It seems to be something height related. Adjusting my ceiling height moves it. Not very practical :/ Then again as I play around with different room sizes I see lots of rooms that aren't too great on here, so maybe I'm just reading the graph wrong?


----------



## sdurani

anjunadeep said:


> I still think I'm setting the room simulator wrong somehow... (hoping?)


Simulators can only take you so far. Even though I brought up the quarter point nulls, it's always possible that they won't be much of a real-world problem. What if the room walls are flexible enough to make the nulls less distinct and noticeable? What if program material has enough satisfying bass that you don't notice the lack of it at one particular frequency? What if the null is really narrow, so it is audible when you're leaning on the left armrest of the seat but not noticeable when you're sitting up straight? So what looks like a potential problem in theory (and in the simulator) might not be worth expending resources on IF it's not so noticeable in real life.


----------



## anjunadeep

nathan_h said:


> First, get rid of the delay. For this step, it confuses things. Leave the subs in the corners for now.
> 
> Second, move the listening head position up and down. Does that change the 50hz dip?
> 
> Move the listener head forward a few feet and backward a few feet and sideways a few feet. Does that change it?
> 
> If you are dealing with a room height mode, then changing the listener head position up and down can help..or at least should change that dip.
> 
> If, on the other hand, horizontal movement changes the dip, then you are dealing with a mode in a different direction.
> 
> (If you are dealing with a height mode, and you cannot realistically move the listening head to a better spot in terms of height, that a small riser might help OR you can consider moving the subs off the floor, which will have the same kind of impact to where vertical modes fall as moving the listener head position did.)


Thanks. Going to try this. I'm looking at Triad Silver Sub Onwalls, which are long and thin. I can raise the subwoofer a bit just by orientation since they're 33" high (8" deep). These fit behind my screen wall easier...

Here is 1ft above (purple live) which makes it worse, the bit darker gray line is below 1ft (not much difference).











Flipping the screen wall subwoofers. They're 33" tall, so I guess I'll say the driver center would be maybe 25" high... hmmm that didn't do much either...


----------



## anjunadeep

sdurani said:


> Simulators can only take you so far. Even though I brought up the quarter point nulls, it's always possible that they won't be much of a real-world problem. What if the room walls are flexible enough to make the nulls less distinct and noticeable? What if program material has enough satisfying bass that you don't notice the lack of it at one particular frequency? What if the null is really narrow, so it is audible when you're leaning on the left armrest of the seat but not noticeable when you're sitting up straight? So what looks like a potential problem in theory (and in the simulator) might not be worth expending resources on IF it's not so noticeable in real life.


I mean I will be able to move the subwoofers anywhere along my front and rear walls when the theater is complete. So, I have that advantage.. behind the screen wall they're hidden, don't even have to worry about visual wire hiding. The rear wall I may actually build ANOTHER screen wall (with no screen lol) so the surround backs and rear subs are hidden and acoustic treatments back there would be hidden if I did that, so that's another place I can really do whatever when things are done. Maybe I'm overthinking?


----------



## sdurani

nathan_h said:


> I'm agreeing with you. His rooms used in the original models, and the physical testing, may not reflect real rooms that many of us have. But based on real rooms confirming his math, one can THEN use his math for many different sized rooms and many different seating locations that more accurately reflect real rooms.


The issue isn't the math but that his real room confirmation placed 16 microphones in a space that can only fit 2 home theatre recliners. If you were to lay out 16 seats (4 rows deep, 4 seats across) in a home theatre and measure the seat to seat consistency with subs placed in 4 corners, you might be in for a surprise compared to what you expected from reading the Welti research.


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## kiddbios

Forgive my ignorance, when you're saying 1/4 placement, is that the midpoint placement or something different?


----------



## sdurani

kiddbios said:


> Forgive my ignorance, when you're saying 1/4 placement, is that the midpoint placement or something different?


Subs centered at the ¼ and ¾ points of a room dimension.


----------



## anjunadeep

kiddbios said:


> Forgive my ignorance, when you're saying 1/4 placement, is that the midpoint placement or something different?


No worries. It's the boxes that are 3' 3" from my walls. So 1/4 of the length from each sidewall on the front and rear walls. I put a box around them (red) for ya. Rear subs are directly below the rear speakers so it's a bit confusing in the drawing.


----------



## nathan_h

sdurani said:


> Simulators can only take you so far. Even though I brought up the quarter point nulls, it's always possible that they won't be much of a real-world problem. What if the room walls are flexible enough to make the nulls less distinct and noticeable? What if program material has enough satisfying bass that you don't notice the lack of it at one particular frequency? What if the null is really narrow, so it is audible when you're leaning on the left armrest of the seat but not noticeable when you're sitting up straight? So what looks like a potential problem in theory (and in the simulator) might not be worth expending resources on IF it's not so noticeable in real life.


Agree 100%. None of the modeling will be 100% accurate. And in fact, room construction techniques are such that *every modeling exercise will be inaccurate*. It is just likely to be *less inaccurate* than any other rule of thumb or predictive exercise. And until a room is built, all one can do is model/predict, measure *other* rooms and see how those perform versus prediction, etc.



sdurani said:


> The issue isn't the math but that his real room confirmation placed 16 microphones in a space that can only fit 2 home theatre recliners. If you were to lay out 16 seats (4 rows deep, 4 seats across) in a home theatre and measure the seat to seat consistency with subs placed in 4 corners, you might be in for a surprise compared to what you expected from reading the Welti research.


Okay, I'll admit I haven't had the need for a theater that large. I've just assumed that since REW and the modeling software accurately predicted my smaller rooms (eg, two rows of three or four seats each) that they would also be a good guidepost for larger rooms. 

I see people like Erskine and Grimani default to four corner subs because (in their words) that tends to create a workable baseline for calibration and optimization. 

But I would love to see measurement data for those larger rooms, if you are willing to share.



anjunadeep said:


> I mean I will be able to move the subwoofers anywhere along my front and rear walls when the theater is complete. So, I have that advantage.. behind the screen wall they're hidden, don't even have to worry about visual wire hiding. The rear wall I may actually build ANOTHER screen wall (with no screen lol) so the surround backs and rear subs are hidden and acoustic treatments back there would be hidden if I did that, so that's another place I can really do whatever when things are done. Maybe I'm overthinking?


No, I think if you can do it the way you describe, you are in for a world of awesome sound. Having that much freedom of movement for the subs after the room is built means you can measure and move them. That way you don't have to just settle for what the modeling predicted (using electronics to address the shortfall between model and reality.)

Having that much flexibility should be a big advantage when it comes to finalizing things. 

I sure wish other manufacturers would make slim subs for such situations. I was moderately excited by SVS announcing some in wall subs that would have that kind of profile, but they have done the smart thing and made the enclosure small, targeting DIY retrofits instead of major installs like Triad or JL Audio do with their slim subs.


----------



## kiddbios

Here are my REW measurements. I took 1 set of measurements with Dirac filters and Dirac Live Bass Management on. Please note I only have Dirac correcting below 500Hz. The 2nd set of measurements is with a barebones manual tuning. Only levels and delay has been set. There is no EQ applied. Psychoacoustic smoothing is applied.


All Measurements



LF Dirac Harman +6 All SPL:






LF Manual All SPL:






LF Dirac Harman +6 RT60:









LF Manual RT60:






RF Dirac Harman +6 All SPL:






RF Manual All SPL:









RF Dirac Harman +6 RT60:






RF Manual RT60:






CC Dirac Harman +6 All SPL:









CC Manual All SPL:






CC Dirac Harman +6 RT60:






CC Manual RT60:









Combined All SPL Measurements:


----------



## kiddbios

anjunadeep said:


> No worries. It's the boxes that are 3' 3" from my walls. So 1/4 of the length from each sidewall on the front and rear walls. I put a box around them (red) for ya. Rear subs are directly below the rear speakers so it's a bit confusing in the drawing.


What if 1/4 point on the rear wall puts the subs directly behind a row of theater chair seating? That would be the case in my setup. Currently I have each of the front subs at ~1/4 and the rear subs in the corners. I could easily move them to 1/4, but then they'd be right between the wall and the backs of my theater seats.


----------



## nathan_h

kiddbios said:


> What if 1/4 point on the rear wall puts the subs directly behind a row of theater chair seating? That would be the case in my setup. Currently I have each of the front subs at ~1/4 and the rear subs in the corners. I could easily move them to 1/4, but then they'd be right between the wall and the backs of my theater seats.


Bass waves are long. Typically unless there is some overtone way above the crossover region, or an intentional effort to have them couple to the room like a bass shaker, you don't hear them until they have bounced off a wall (sometimes multiple walls) in your room.


----------



## nathan_h

kiddbios said:


> Here are my REW measurements. I took 1 set of measurements with Dirac filters and Dirac Live Bass Management on. Please note I only have Dirac correcting below 500Hz. The 2nd set of measurements is with a barebones manual tuning. Only levels and delay has been set. There is no EQ applied. Psychoacoustic smoothing is applied.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 3237448
> View attachment 3237449
> View attachment 3237450
> View attachment 3237453
> View attachment 3237454
> View attachment 3237452
> View attachment 3237452
> View attachment 3237456
> View attachment 3237455
> View attachment 3237457
> View attachment 3237458
> View attachment 3237459
> View attachment 3237460


The forum software is acting weird and won't show me any of those right now.


----------



## kiddbios

nathan_h said:


> Bass waves are long. Typically unless there is some overtone way above the crossover region, or an intentional effort to have them couple to the room like a bass shaker, you don't hear them until they have bounced off a wall (sometimes multiple walls) in your room.


So it is OK to put them between the back wall and furniture?



nathan_h said:


> The forum software is acting weird and won't show me any of those right now.


Probably because I was editing the post. None of the names came through on the images, so there was no way to tell what was what.


----------



## nathan_h

kiddbios said:


> So it is OK to put them between the back wall and furniture?


Usually no problem.


----------



## nathan_h

kiddbios said:


> Here are my REW measurements. I took 1 set of measurements with Dirac filters and Dirac Live Bass Management on. Please note I only have Dirac correcting below 500Hz. The 2nd set of measurements is with a barebones manual tuning. Only levels and delay has been set. There is no EQ applied. Psychoacoustic smoothing is applied.
> 
> 
> All Measurements
> 
> 
> 
> LF Dirac Harman +6 All SPL:
> View attachment 3237480
> LF Manual All SPL:
> View attachment 3237481
> LF Dirac Harman +6 RT60:
> View attachment 3237486
> 
> 
> 
> LF Manual RT60:
> View attachment 3237488
> RF Dirac Harman +6 All SPL:
> View attachment 3237490
> RF Manual All SPL:
> View attachment 3237483
> 
> 
> 
> RF Dirac Harman +6 RT60:
> View attachment 3237492
> RF Manual RT60:
> View attachment 3237491
> CC Dirac Harman +6 All SPL:
> View attachment 3237484
> 
> 
> 
> CC Manual All SPL:
> View attachment 3237487
> CC Dirac Harman +6 RT60:
> View attachment 3237482
> CC Manual RT60:
> View attachment 3237485
> 
> 
> 
> Combined All SPL Measurements:
> View attachment 3237489


Those measurements are not bad! Especially with DIRAC in place thats a very nice frequency response.

The decay times above the room transition are about as short as one would want (some people prefer a more live sound) at about .2 seconds. So you might want to double up some panels that are currently spread about a bit. That will allow a little more liveliness and absorb a little lower. But that would be a preference thing.

The decay time does get a little crazy below the room transition frequency. How large is this room? I'm guessing maybe 300 or 400 sq ft? But that's sort of normal.

Anyway, I suppose that repositioning the subs might engender more beneficial interactions between them. Its free to try and I think worth it.

I am scared by the amount of 1.5" treatment you have. If you have step those off the wall a few inches, double them up, etc, that will start to get into the sub 400 hz region where things are little hot in your room. 

And then, yes, I think the other thing you mentioned which is essentially piling stacks of insulation in the area behind the screen, and speakers (filling as much of that cavity as you can, even garbage bags full of fluffy stuff from the hardware store will do the trick) could get you closer to the sound you seek. You idea of making stacks of panels out of OC703 is prettier of course, and effective.

I wouldn't add more high frequency absorption in this room at all. In fact, some people would call it a little on the dead side. The thing I might do is making the existing panels deeper either by doubling them up or standing them off the wall a couple inches with spacers. (This assumes they don't have a rigid back and that sound can pass through them.)


----------



## sdurani

nathan_h said:


> Okay, I'll admit I haven't had the need for a theater that large.


Not sure what this has to do with you needing a large theatre. I was simply pointing out that Welti's research into seat to seat consistency across 16 seats is based on the unrealistic premise that all 16 seats can fit in a 6' x 6' area. Like being told that you can get seat to seat consistency across 4 seats in a small room only to find out that it requires all 4 seats to fit into a 3' x 3' square. Ain't gonna happen. But that's the logistical gymnastics needed for the approach to work.


----------



## nathan_h

sdurani said:


> Not sure what this has to do with you needing a large theatre. I was simply pointing out that Welti's research into seat to seat consistency across 16 seats is based on the unrealistic premise that all 16 seats can fit in a 6' x 6' area. Like being told that you can get seat to seat consistency across 4 seats in a small room only to find out that it requires all 4 seats to fit into a 3' x 3' square. Ain't gonna happen. But that's the logistical gymnastics needed for the approach to work.


I’m just saying his modeling worked great in a smaller room with two rows of seats. While his original measurments used a seating area that might not match other rooms, the method and math extrapolate well into other sized rooms and other seating arrangements.


----------



## sdurani

nathan_h said:


> I’m just saying his modeling worked great in a smaller room with two rows of seats. While his original measurments used a seating area that might not match other rooms, the method and math extrapolate well into other sized rooms and other seating arrangements.


How does he avoid the nulls at the quarter points?


----------



## nathan_h

Here are three different configurations.

My goal is the least seat to seat variation.

Secondary goal is avoiding wide nulls since peaks are easier to tame and wide nulls are both audible and the hardest to tame....especially if they change from seat to seat.

No configuration is perfect, so one pickes one's poison (or, at least, what creates the most manageable problem) and proceeds.



http://imgur.com/a/hXthrCR


----------



## kiddbios

nathan_h said:


> Those measurements are not bad! Especially with DIRAC in place thats a very nice frequency response.
> 
> The decay times above the room transition are about as short as one would want (some people prefer a more live sound) at about .2 seconds. So you might want to double up some panels that are currently spread about a bit. That will allow a little more liveliness and absorb a little lower. But that would be a preference thing.
> 
> The decay time does get a little crazy below the room transition frequency. How large is this room? I'm guessing maybe 300 or 400 sq ft? But that's sort of normal.
> 
> Anyway, I suppose that repositioning the subs might engender more beneficial interactions between them. Its free to try and I think worth it.
> 
> I am scared by the amount of 1.5" treatment you have. If you have step those off the wall a few inches, double them up, etc, that will start to get into the sub 400 hz region where things are little hot in your room.
> 
> And then, yes, I think the other thing you mentioned which is essentially piling stacks of insulation in the area behind the screen, and speakers (filling as much of that cavity as you can, even garbage bags full of fluffy stuff from the hardware store will do the trick) could get you closer to the sound you seek. You idea of making stacks of panels out of OC703 is prettier of course, and effective.
> 
> I wouldn't add more high frequency absorption in this room at all. In fact, some people would call it a little on the dead side. The thing I might do is making the existing panels deeper either by doubling them up or standing them off the wall a couple inches with spacers. (This assumes they don't have a rigid back and that sound can pass through them.)


Thank you for all the evaluation and feedback. The REW room calculator is saying that putting a bunch of absorption at the front of the room will improve the bass, and it sounds like you're saying the same thing. 

What does a "good" RT60 graph look like? I know that what I'm ultimately trying to achieve is something that sounds good to my ears, but until I very recently started using REW and actually spending the time to understand graphs, I felt like it was blind trial and error, with a high probability for losing my bearings around what changed and what I was actually hearing (or not hearing). It is helpful to have something somewhat objective to look at to help understand what the sound is actually doing in your room.


----------



## nathan_h

A good RT60 graph looks like a flat line — above the room transition frequency (which changes based on room size but typically starts in the 250 to 400 hz range). And that flat line is ideally sitting at under .3 seconds in a smaller room up to .5 seconds in a larger domestic room. Yours is on the dry end of the ideal range, mostly flat (good) and about the .2 seconds range. Some people might find that there isn’t enough airiness in such a room but I think in a critical listening room for multichannel sound that’s not a bad number. If this was a two channel room that might impact your sense of spaciousness.

Yes I think if you can put lots of thick absorption in the front of the room behind that furniture, it will likely do nice things for your bass response and won’t over absorb your treble, since it is behind a reflective surface: the bass will get back there and get absorbed but the treble won’t much.

And part of the reason I’m saying that is it seems like reducing the amount of time bass bounces around your room may give you a tighter sense of bass response. But RT60 even though it looks horrible in your bass region is not a valid way to measure those frequencies so you can’t really judge that region by RT60. That region is judged by frequency response and yours is good without DIRAC and then excellent with DIRAC.


----------



## nathan_h

anjunadeep said:


> No worries. It's the boxes that are 3' 3" from my walls. So 1/4 of the length from each sidewall on the front and rear walls. I put a box around them (red) for ya. Rear subs are directly below the rear speakers so it's a bit confusing in the drawing.
> 
> View attachment 3237437


This is a nice design. Do you have a build thread. So few people do these rooms with smaller numbers of seats but it is the way I’m leaning for my next build.


----------



## sdurani

nathan_h said:


> Secondary goal is avoiding wide nulls since peaks are easier to tame and wide nulls are both audible and the hardest to tame....especially if they change from seat to seat.


They appear to be a wash moving front to back but the second one is a little better when moving side to side.


----------



## anjunadeep

nathan_h said:


> This is a nice design. Do you have a build thread. So few people do these rooms with smaller numbers of seats but it is the way I’m leaning for my next build.


Yeah, 99% of the time it's me or me and one other person, and my room is small so it seemed like a big compromise to add a second row. I don't have a build thread, I go back and forth about making one. I've got the room framed so far but doing the rest of the project (other rooms, theater will be last). I take tons of photos, so I may make one a bit later on when starting to work on it more heavily. I'm subscribed to your thread!


----------



## nathan_h

anjunadeep said:


> Yeah, 99% of the time it's me or me and one other person, and my room is small so it seemed like a big compromise to add a second row. I don't have a build thread, I go back and forth about making one. I've got the room framed so far but doing the rest of the project (other rooms, theater will be last). I take tons of photos, so I may make one a bit later on when starting to work on it more heavily. I'm subscribed to your thread!


I commend you for making the decision to do a single row. 

I swore I would do that this time and.......I keep hesitating!

Anyway if you already have a lot of photos, I would encourage you to create a build thread. 

Not that it would apply to you, but in my case, my last build thread, with photos, helped me catch a few mistakes -- ie, some folks pointed out suboptimal choices I had made, that were easy to fix during the build.

But more to the point, I am curious to learn form what you are doing.


----------



## jdlynch

Question about super-chunk style corner bass traps:

I’ve got my plans and material list to begin building my super-chunk corner bass traps. They will be made in 4ft sections and I will be placing them in three of my four room corners. When complete they will be 30 1/2” across the front face.

My question is: should I fill the complete triangle with insulation (Roxul safe and sound) or should I leave an air space in the rear corner? I’ve seen varying opinions and wondering what the consensus is for the maximum absorption. If an air space is recommended, then how much air space?


----------



## nathan_h

Max absorboption: fill the space. But that is a technicality. It's not a ton more absoprtion. 

More important is DEEP (low frequency) absorption -- and the air gap is the cheap way to achieve that versus solid insulation.

So if you have budget constraints or it's smply easier to leave a gap, do so. If you have a specific amount of insulation and the choice is to have a gap or place it against the wall, DEFINITELY leave a gap. That will help you absorb lower frequencies.


----------



## jdlynch

nathan_h said:


> Max absorboption: fill the space. But that is a technicality. It's not a ton more absoprtion.
> 
> More important is DEEP (low frequency) absorption -- and the air gap is the cheap way to achieve that versus solid insulation.
> 
> So if you have budget constraints or it's smply easier to leave a gap, do so. If you have a specific amount of insulation and the choice is to have a gap or place it against the wall, DEFINITELY leave a gap. That will help you absorb lower frequencies.


How many inches of air gap would you recommend?


----------



## nathan_h

Its not about how much of an air gap. Its about the distance from the surface of the insulation to the surface of the wall. If you have make that distance six feet, great! But I'll bet in most rooms, 20 to 30" is about all the space one can spare.

If you can fill all 30" with insulation, that's great. But many people are on a budget. So using 15" of insulation, and then 15" of air, if you can't afford 30" of insulation, is a good idea. WAAAAY better than just shrinking the size of the trap to 15".


----------



## carp

nathan_h said:


> A good RT60 graph looks like a flat line — above the room transition frequency (which changes based on room size but typically starts in the 250 to 400 hz range). And that flat line is ideally sitting at under .3 seconds in a smaller room up to .5 seconds in a larger domestic room. Yours is on the dry end of the ideal range, mostly flat (good) and about the .2 seconds range. Some people might find that there isn’t enough airiness in such a room but I think in a critical listening room for multichannel sound that’s not a bad number. If this was a two channel room that might impact your sense of spaciousness.
> 
> Yes I think if you can put lots of thick absorption in the front of the room behind that furniture, it will likely do nice things for your bass response and won’t over absorb your treble, since it is behind a reflective surface: the bass will get back there and get absorbed but the treble won’t much.
> 
> And part of the reason I’m saying that is it seems like reducing the amount of time bass bounces around your room may give you a tighter sense of bass response. But RT60 even though it looks horrible in your bass region is not a valid way to measure those frequencies so you can’t really judge that region by RT60. That region is judged by frequency response and yours is good without DIRAC and then excellent with DIRAC.



Hey Nathan and Sanjay, I don't know how to read/interpret the decay from looking at this. I have read many times that you want to be between .2 and .4 depending on personal taste so I'm curious where I'm at now. Can you tell from looking at this graph or is it somewhere else on REW? I assume it's not good that the purple and blue line are so low! 

thanks!!

Thanks!!


----------



## nathan_h

carp said:


> Hey Nathan and Sanjay, I don't know how to read/interpret the decay from looking at this. I have read many times that you want to be between .2 and .4 depending on personal taste so I'm curious where I'm at now. Can you tell from looking at this graph or is it somewhere else on REW? I assume it's not good that the purple and blue line are so low!
> 
> thanks!!
> 
> Thanks!!
> View attachment 3237863


You ahve cut off the left hand scale so I can't say for sure. But the red and yellow lines are the important ones. They are pretty flat/linear down to below 200 hz which is likely your room transition frequency, which is what you want to see.

But I cannot tell from the screen shot what level they are at since the scale on the left is missing.


----------



## jdlynch

nathan_h said:


> Its not about how much of an air gap. Its about the distance from the surface of the insulation to the surface of the wall. If you have make that distance six feet, great! But I'll bet in most rooms, 20 to 30" is about all the space one can spare.
> 
> If you can fill all 30" with insulation, that's great. But many people are on a budget. So using 15" of insulation, and then 15" of air, if you can't afford 30" of insulation, is a good idea. WAAAAY better than just shrinking the size of the trap to 15".


Thanks. One more question:

I've decided to cover my traps with black GOM as that appears to be the standard. Does anyone know how black that fabric will look when it's up against a black velvet wall fabric?


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## nathan_h

I saw a photo comparing GOM and Velvet several years ago. Nothing looks as black as velvet. 

But since it is a bass trap, you don't really need GOM fabric. Bass waves can easily pass through other fabrics. I have seen people have success covering bass traps in Royalty 3 velvet from Joann's, or Plush Triple Velvet BLACK from Sy Fabrics.


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## jdlynch

Velvet would be awesome and a perfect match. However, wouldn't the velvet fabric act as a "range limiter" ? I realize bass waves would go right through velvet, but would it not reflect the higher frequencies?


----------



## carp

nathan_h said:


> You ahve cut off the left hand scale so I can't say for sure. But the red and yellow lines are the important ones. They are pretty flat/linear down to below 200 hz which is likely your room transition frequency, which is what you want to see.
> 
> But I cannot tell from the screen shot what level they are at since the scale on the left is missing.


Whoops...

Here you go:


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## nathan_h

That’s a little on the dry side. .2 to .3 is sometimes what people like versus .15 like what you have. But it’s not crazy versus some mastering rooms. No more absorption! But if you like the sound I would not change anything.




carp said:


> Whoops...
> 
> Here you go:
> 
> View attachment 3238084


----------



## nathan_h

jdlynch said:


> Velvet would be awesome and a perfect match. However, wouldn't the velvet fabric act as a "range limiter" ? I realize bass waves would go right through velvet, but would it not reflect the higher frequencies?


Yes but unless you need more high frequency absorption that is okay. Those velvets I mentioned are pretty sheer versus others you might be familiar with So they won’t be a problem imo.


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## carp

nathan_h said:


> That’s a little on the dry side. .2 to .3 is sometimes what people like versus .15 like what you have. But it’s not crazy versus some mastering rooms. No more absorption! But if you like the sound I would not change anything.


Thanks!  I see now how you are reading the graph. 

Other than the front wall I don't have a ton of absorption. The other walls/ceiling are well below 15%. My front wall is all 15" of pink fluffy other than where the 2 stacks of subs are and the LRC speakers. 
I haven't seen much info on front walls in any of the recent videos posted. Is it good to do what I have done or is the front wall like any other wall and I should use a combo of absorption, diffusion, and bare wall? 

I do plan on putting in some shelves so that the insulation isn't so packed, but not sure how far apart I should have the shelving.


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## nathan_h

carp said:


> Thanks! I see now how you are reading the graph.
> 
> Other than the front wall I don't have a ton of absorption. The other walls/ceiling are well below 15%. My front wall is all 15" of pink fluffy other than where the 2 stacks of subs are and the LRC speakers.
> I haven't seen much info on front walls in any of the recent videos posted. Is it good to do what I have done or is the front wall like any other wall and I should use a combo of absorption, diffusion, and bare wall?
> 
> I do plan on putting in some shelves so that the insulation isn't so packed, but not sure how far apart I should have the shelving.
> 
> View attachment 3238097


The measurements aren't bad. IIRC, the ITU specification for dubbing rooms is .15 seconds decay time. So unless you dislike the sound, I don't see any reason to change it.

(I might be tempted to cover those rolls with fabric, both to lesson the possibility of airborne particles and because light going through your screen might light it up a bit.)


----------



## carp

nathan_h said:


> The measurements aren't bad. IIRC, the ITU specification for dubbing rooms is .15 seconds decay time. So unless you dislike the sound, I don't see any reason to change it.
> 
> (I might be tempted to cover those rolls with fabric, both to lesson the possibility of airborne particles and because light going through your screen might light it up a bit.)


I do have it covered, I took that picture right as I finished stacking the insulation and before I covered it - good call though.


----------



## anjunadeep

carp said:


> Thanks! I see now how you are reading the graph.
> 
> Other than the front wall I don't have a ton of absorption. The other walls/ceiling are well below 15%. My front wall is all 15" of pink fluffy other than where the 2 stacks of subs are and the LRC speakers.
> I haven't seen much info on front walls in any of the recent videos posted. Is it good to do what I have done or is the front wall like any other wall and I should use a combo of absorption, diffusion, and bare wall?
> 
> I do plan on putting in some shelves so that the insulation isn't so packed, but not sure how far apart I should have the shelving.
> 
> View attachment 3238097


I itch just looking at that! 

I want to have some insulation behind my screen like that when I do my screen wall and have been reading about Roxul ...which is now rebranded to Rockwool. Apparently it holds together better and keeps shape easier. It's also a darker color. I was thinking of essentially building wall framing out a bit to make easy forms to stuff it into. I'm only interested in going 6" deep though, you seem to be wanting more of a baffle wall?


----------



## carp

anjunadeep said:


> I itch just looking at that!
> 
> I want to have some insulation behind my screen like that when I do my screen wall and have been reading about Roxul ...which is now rebranded to Rockwool. Apparently it holds together better and keeps shape easier. It's also a darker color. I was thinking of essentially building wall framing out a bit to make easy forms to stuff it into. I'm only interested in going 6" deep though, you seem to be wanting more of a baffle wall?


Haha, yeah it's not fun to work with for sure. 

I did this around 5 years ago and like the results but always wonder if it can be improved. I know it can be improved by putting in shelves so it's not so compressed but what I don't know is if I'd be better off taking some of it out so that there are pockets of bare wall, spots for diffusion panels, and then the rest pink fluffy. I have never seen any expert address that question. 

Mine is like a baffle wall because I don't have much space behind my screen and I wanted to go as thick as possible to affect the lowest frequencies that I possibly could. I have less than 2 feet from my screen to my wall, so barely enough room to toe my L and R speakers like I want and then I filled in almost all of it with the insulation. The reason it is like a baffle wall (but not a true baffle wall the way I understand it) is that I wanted to have the insulation as far from the wall as possible so that I would have an air gap.


----------



## anjunadeep

carp said:


> Haha, yeah it's not fun to work with for sure.
> 
> I did this around 5 years ago and like the results but always wonder if it can be improved. I know it can be improved by putting in shelves so it's not so compressed but what I don't know is if I'd be better off taking some of it out so that there are pockets of bare wall, spots for diffusion panels, and then the rest pink fluffy. I have never seen any expert address that question.
> 
> Mine is like a baffle wall because I don't have much space behind my screen and I wanted to go as thick as possible to affect the lowest frequencies that I possibly could. I have less than 2 feet from my screen to my wall, so barely enough room to toe my L and R speakers like I want and then I filled in almost all of it with the insulation. The reason it is like a baffle wall (but not a true baffle wall the way I understand it) is that I wanted to have the insulation as far from the wall as possible so that I would have an air gap.


There is surely someone here who can give you a better answer, but I've seen suggestions for the front wall to be covered by some percentage (15-20%), I've seen suggestions to do a hard baffle wall with some fairly thin layers of absorption material on top of it, I've seen suggestions to put mixtures of diffusion and absorption. I have read and seen confirmed here fairly regularly that you don't need the super deep bass traps if you're doing modal manipulation using multiple subs, so if you have subs in the front and back of your room, you probably don't need a total cavern of absorption at the front of the room. If you don't need that total cavern, well that might allow you to TRY some different things and see what you like the best. Like maybe you could make some 6" deep panels and get some diffusers and try different combinations back there. Different amounts of absorption (maybe try starting at 15%, then try 30%, etc.) Take measurements. There are probably a few correct answers. I'm convinced some of this comes down to preference too. 

I will say I was in a small room once that was too dead for my tastes. It made the speakers pretty easy to locate. So there is for sure something to finding the right balance. 

When you do handle that pink stuff, get yourself a Tyvek suit and a respirator with an exhale valve.


----------



## carp

anjunadeep said:


> There is surely someone here who can give you a better answer, but I've seen suggestions for the front wall to be covered by some percentage (15-20%), I've seen suggestions to do a hard baffle wall with some fairly thin layers of absorption material on top of it, I've seen suggestions to put mixtures of diffusion and absorption. I have read and seen confirmed here fairly regularly that you don't need the super deep bass traps if you're doing modal manipulation using multiple subs, so if you have subs in the front and back of your room, you probably don't need a total cavern of absorption at the front of the room. If you don't need that total cavern, well that might allow you to TRY some different things and see what you like the best. Like maybe you could make some 6" deep panels and get some diffusers and try different combinations back there. Different amounts of absorption (maybe try starting at 15%, then try 30%, etc.) Take measurements. There are probably a few correct answers. I'm convinced some of this comes down to preference too.
> 
> I will say I was in a small room once that was too dead for my tastes. It made the speakers pretty easy to locate. So there is for sure something to finding the right balance.
> 
> When you do handle that pink stuff, get yourself a Tyvek suit and a respirator with an exhale valve.


I really do like to experiment, so I think when I get some free time I'll just try out the different options for the front wall and see what I like. 

I really am surprised at how "dead" my room looks according to measurements on REW. I've been in dead rooms and it feels oppressive and the sound of a conversation just doesn't sound right. That's not the case in my room. So, who knows, in the end I may circle all the way around to exactly where I am now with the whole front wall covered in insulation - but I'll never know that if I don't try other things. 
So far all I have tried on the front wall is all or nothing (100 percent bare wall vs. 100 percent pink fluffy - other than where the subs and speakers are). 

It really wasn't that awful working with the pink fluffy. I just used gloves and a mask and didn't notice any issues with itching or coughing. I think it helped that I opened it on our screened porch and left it there for a few days before moving it into the basement.

Thanks for your advice!


----------



## jdlynch

I am getting ready to build some corner chunk style bass traps. I can buy Roxul safe and sound at my local Home Depot. The other option is Owens corning 703 which I need to order. Which one would be preferred for broadband absorption? The Roxul is only 2 1/2 lb/ft3 density.


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## nathan_h

If I am reading the data right the OC absorbs a bit more sound but costs more as well. If space is plentiful is go with rock wool imo. Easier to get, cheaper and depth matters just as much if not more than density since depths what gets you impact at lower frequencies. 

If space is more limited than funds, and you need every inch to count, maybe paying more for OC makes sense.


----------



## wickflair

Still doing some reading on this thread, but hoping for some good advice. 

I am starting to frame and insulate my walls this weekend. Before too long I will be focusing my time on improving the sound quality of the room. My room will be a multil- purpose room. It will be both used for 5.2.2 video as well as listening to 2.1 audio. This is not a dedicated room, so it will also have things such as tables and a bar for hanging out. 

The room will also have a projector screen 120-150" which will take up most of the front wall. 
Room will be ~ 400-450sqr feet. 

Where should I get started? What areas should I prioritize? I am open to any suggestions you guys have. 

Thank you!


----------



## nathan_h

wickflair said:


> Still doing some reading on this thread, but hoping for some good advice.
> 
> I am starting to frame and insulate my walls this weekend. Before too long I will be focusing my time on improving the sound quality of the room. My room will be a multil- purpose room. It will be both used for 5.2.2 video as well as listening to 2.1 audio. This is not a dedicated room, so it will also have things such as tables and a bar for hanging out.
> 
> The room will also have a projector screen 120-150" which will take up most of the front wall.
> Room will be ~ 400-450sqr feet.
> 
> Where should I get started? What areas should I prioritize? I am open to any suggestions you guys have.
> 
> Thank you!


Post a diagram of the planned room and it may be obvious what opportunities there are. To be particularly thorough you can share what speakers you will be using.


----------



## squared80

wickflair said:


> Still doing some reading on this thread, but hoping for some good advice.
> 
> I am starting to frame and insulate my walls this weekend. Before too long I will be focusing my time on improving the sound quality of the room. My room will be a multil- purpose room. It will be both used for 5.2.2 video as well as listening to 2.1 audio. This is not a dedicated room, so it will also have things such as tables and a bar for hanging out.
> 
> The room will also have a projector screen 120-150" which will take up most of the front wall.
> Room will be ~ 400-450sqr feet.
> 
> Where should I get started? What areas should I prioritize? I am open to any suggestions you guys have.
> 
> Thank you!


Start your own build thread in the applicable forum.


----------



## wickflair

squared80 said:


> Start your own build thread in the applicable forum.


 This is the right thread I thought?


----------



## nathan_h

wickflair said:


> This is the right thread I thought?


I see people use both methods. If you are still at the building stage, you might find it useful to start a thread that covers more than just acoustic treatment but your theater space as a whole. This could give you the opportunity to discuss many topics which are interrelated.

(Example, but not what you are asking about: When making a decision on a screen one has to consider the projector, and room, etc, and vice versa, so asking about one without the context of the others becomes a chicken and egg problem.)

On the other hand, this thread is full of people asking a question like yours, and that works too, though usually they are in a finished room where almost the only variable left is acoustic treatment (and some setup).


----------



## wickflair

nathan_h said:


> I see people use both methods. If you are still at the building stage, you might find it useful to start a thread that covers more than just acoustic treatment but your theater space as a whole. This could give you the opportunity to discuss many topics which are interrelated.
> 
> (Example, but not what you are asking about: When making a decision on a screen one has to consider the projector, and room, etc, and vice versa, so asking about one without the context of the others becomes a chicken and egg problem.)
> 
> On the other hand, this thread is full of people asking a question like yours, and that works too, though usually they are in a finished room where almost the only variable left is acoustic treatment (and some setup).


I already have the screen, paint, projector and all that pretty much figured out. Right now my main focus in on improving sound quality within the room. I will draft up the layout and make a seperate post with all the details.


----------



## wickflair

squared80 said:


> Start your own build thread in the applicable forum.


Here is my own post with more specifics. Hopefully this helps!









Improving Acoustic suggestions


Hello All! I was told to make my own post for this so here I go. I am looking for direction on making the most out out of this area and have the best possible sound. This room will be multi-use. 5.2.2, 2.1 music, and just hanging out. Attached is a rough draft of how I expect it to look once...




www.avsforum.com


----------



## nathan_h

I responded in your new thread.


----------



## filmgeek47

So I got some great advice in this thread a couple of years ago RE DIY treatment for my room. The concensus at the time was that I needed to swap some of my 2” panels for thicker absorption as I was over-treating the high end and throwing the FR out of balance. It also sounded Like putting some scatter plates on my diffusion panels would be helpful. Naturally life happened and I never got around to it.

Looking at this again now, and I was wondering if there’s any more detailed info on making a good DIY scatter plate. I’ve seen some people point to calculators but to be honest I’m not sure how to take what that’s giving me and turn it into a practical thing I can cut/build. Any thoughts?


----------



## nathan_h

I’d build the thicker panels and measure the decay time in the room before deciding on scatter plates.

A lot will depend on your room, your speakers, and where you place the panels.


----------



## void.pointer

Is there a service that will build acoustic treatments for you if you tell them your room size and speaker layout? Something that has a high amount of WAF (Wife Approval Factor) would be ideal (e.g. pick the texture, color). They'd ship it to me and I just hang them on the wall.


----------



## nathan_h

GIK


----------



## MoMann

Anyone order from GIK recently? Are they still super behind on their shipping?


----------



## jdlynch

Anyone compared the effectiveness of acoustimac bass traps, especially their corner Bass traps, to those of GIK? I prefer GIK, but delivery times are longer than I want to wait. Acoustimac appears to have good quality construction, and their delivery times seem reasonable.


----------



## nathan_h

When comparing apples to apples (eg, 24*48*4”) they perform about the same, since they are made from pretty much the same stuff.

GIK has some step up options for tuned traps etc that cost more but do more for specific use cases. Acoustimac has more fit and finish options for a classier look if that matters.


----------



## srslee

I'm looking to purchase a few acoustic panels for a bedroom setup. I placed an order for the GIK 242 panels, but considering cancelling the order and going with ATS based on lead times. One question, I see that the 242 is 3.625" thick while the ATS is 4" thick. Will the extra thickness make any difference such that ATS would provide more value if the costs are the same? One reason I ask is because the absorption coefficients listed on both sites for the two products are quite different, particularly in the lower frequencies (0.68 at 100hz for the Guilford of Maine ATS panel vs. 0.14 at 100hz for the GIK 242).


----------



## nathan_h

srslee said:


> I'm looking to purchase a few acoustic panels for a bedroom setup. I placed an order for the GIK 242 panels, but considering cancelling the order and going with ATS based on lead times. One question, I see that the 242 is 3.625" thick while the ATS is 4" thick. Will the extra thickness make any difference such that ATS would provide more value if the costs are the same? One reason I ask is because the absorption coefficients listed on both sites for the two products are quite different, particularly in the lower frequencies (0.68 at 100hz for the Guilford of Maine ATS panel vs. 0.14 at 100hz for the GIK 242).


The GIK 244 panel is the better comparison. It has a similar amount of acoustic material. Both have similar performance (as one would expect based on their materials). And it is about the same price. I guess it sits a little further off the wall due to the build in air gap. The GOM looks nicer in my opinion.

It’s not clear the testing was done in the same manner by the same lab so the tests may not be 100% comparable.

The ATS should be fine.


----------



## tuskenraider

So I am going to change the wall art in my living room, and maybe adjoining dining room area, and thought I might as well replace it with some acoustical treatments that can substitute as art. With the combined dining area, I've done the best that I can concerning the very limited placement options for my speakers. I'm trying to kill the echo and tame harshness that can be present depending on source, and smooth overall response as best as possible. Wood flooring in the whole area, with one rug as noted in the floorplan. I assume it doesn't make much difference, but I prioritize stereo performance over 5.1 home theater. I've included two REW graphs that shows 2 and 2.1 channel performance in the space. 180° phase with YPAO room correction is the current configuration used. Without the sub at 40 Hz XO, there is a deep hole 50-80 Hz. I've moved speakers around in a 1-1.5ft radius, with no help. Sub has been tried behind/inside the left speaker as well, but performs best in the right corner. Basically, it doesn't look like I can really get good 2 channel performance in this room. Lots of peaks and dips 60-700 Hz. Without further rambling and understanding these panels will not have effect the lowest frequencies, I'm looking at 24"x24"x2" and 24"x36"x2" panels at various websites. In the floor plan drawing are options to hang them. I could get something for every spot, or ignore the dining area, etc. One thing I feel certain about is, since I'm running bi-polar side speakers, I clearly need something on the 3 ft. wall right behind it to stop reflections. Any additional advice or recommendations would be appreciated.


----------



## kalakasan

I've completed REW measurements of my 4 VBSS subs (2 logical) and have some nulls that I'm hoping can be reduced through room treatments first, and then continue with adjustments using a miniDSP HD and possibly MSO. I did an initial subs + center channel 'practice' MSO optimization (3 seat positions) using my REW measurements and the resulting seat-to-seat variance was higher than my liking above 60hz (even with 8 PEQ selected). Moreover, the result after importing the filters into the MiniDSP was disappointing. However, I strongly suspect this it due to user error at some point, so I'm willing to try again.

Here's the MSO response graph:










So while I'm working to get the hang of speaker integration using dsp (if ever!), I've decided to work on applying appropriate room treatments, including bass traps, absorbers/diffusers applied in an aesthetic manner (waf).

My room:


20x15x7'4"
'Home theater' double wall construction (except next to concrete basement walls)
2 layers of 5/8" drywall with Green Glue - walls and ceiling
Decoupled walls and ceiling (clips and hat channel)
7.4.4 (atmos)

Speaker Placement is set in stone. My work is to tame the room given those constraints.

Room Front: MLP is about 8.5' from TV screen.


























A tall bass trap would fit in the left corner
Would a bass trap under the TV and between the front subs be of any benefit?
what about a small bass trap in the space on the right (only sub height)?

Room Rear:


























Room Rear:


Bass trap would fit in left corner
A diffuser would fit on the back wall
Bottom of speaker columns are hollow - fill with roxel?

Room Walls:

- 2" Absorbers at first reflection points (2" offset from wall)

REW Front sub(s) plot:













REW Rear sub(s) plot:












REW Combined plot (Front and Rear):











My guess is the nulls are room modes, and perhaps some front sub sbir?

Am I on the right track here?


----------



## nathan_h

tuskenraider said:


> So I am going to change the wall art in my living room, and maybe adjoining dining room area, and thought I might as well replace it with some acoustical treatments that can substitute as art. With the combined dining area, I've done the best that I can concerning the very limited placement options for my speakers. I'm trying to kill the echo and tame harshness that can be present depending on source, and smooth overall response as best as possible. Wood flooring in the whole area, with one rug as noted in the floorplan. I assume it doesn't make much difference, but I prioritize stereo performance over 5.1 home theater. I've included two REW graphs that shows 2 and 2.1 channel performance in the space. 180° phase with YPAO room correction is the current configuration used. Without the sub at 40 Hz XO, there is a deep hole 50-80 Hz. I've moved speakers around in a 1-1.5ft radius, with no help. Sub has been tried behind/inside the left speaker as well, but performs best in the right corner. Basically, it doesn't look like I can really get good 2 channel performance in this room. Lots of peaks and dips 60-700 Hz. Without further rambling and understanding these panels will not have effect the lowest frequencies, I'm looking at 24"x24"x2" and 24"x36"x2" panels at various websites. In the floor plan drawing are options to hang them. I could get something for every spot, or ignore the dining area, etc. One thing I feel certain about is, since I'm running bi-polar side speakers, I clearly need something on the 3 ft. wall right behind it to stop reflections. Any additional advice or recommendations would be appreciated.
> 
> View attachment 3254977
> 
> 
> View attachment 3254974
> 
> 
> View attachment 3254979
> View attachment 3254982


This is a good plan.

Two things occur to me.

1) Anywhere those panels can be four inches thick, that would be preferable. That gets you wider band absorption. Otherwise you are treating the highest frequencies but leaving the mids to go wild.

2) If you can place a couple panels on the ceiling between you and the front speakers that would likely be worthwhile.


----------



## nathan_h

kalakasan said:


> I've completed REW measurements of my 4 VBSS subs (2 logical) and have some nulls that I'm hoping can be reduced through room treatments first, and then continue with adjustments using a miniDSP HD and possibly MSO. I did an initial subs + center channel 'practice' MSO optimization (3 seat positions) using my REW measurements and the resulting seat-to-seat variance was higher than my liking above 60hz (even with 8 PEQ selected). Moreover, the result after importing the filters into the MiniDSP was disappointing. However, I strongly suspect this it due to user error at some point, so I'm willing to try again.
> 
> Here's the MSO response graph:
> 
> View attachment 3255104
> 
> 
> So while I'm working to get the hang of speaker integration using dsp (if ever!), I've decided to work on applying appropriate room treatments, including bass traps, absorbers/diffusers applied in an aesthetic manner (waf).
> 
> My room:
> 
> 
> 20x15x7'4"
> 'Home theater' double wall construction (except next to concrete basement walls)
> 2 layers of 5/8" drywall with Green Glue - walls and ceiling
> Decoupled walls and ceiling (clips and hat channel)
> 7.4.4 (atmos)
> 
> Speaker Placement is set in stone. My work is to tame the room given those constraints.
> 
> Room Front: MLP is about 8.5' from TV screen.
> 
> View attachment 3255107
> View attachment 3255108
> 
> View attachment 3255109
> 
> 
> 
> A tall bass trap would fit in the left corner
> Would a bass trap under the TV and between the front subs be of any benefit?
> what about a small bass trap in the space on the right (only sub height)?
> 
> Room Rear:
> 
> View attachment 3255110
> View attachment 3255111
> 
> 
> View attachment 3255112
> 
> 
> Room Rear:
> 
> 
> Bass trap would fit in left corner
> A diffuser would fit on the back wall
> Bottom of speaker columns are hollow - fill with roxel?
> 
> Room Walls:
> 
> - 2" Absorbers at first reflection points (2" offset from wall)
> 
> REW Front sub(s) plot:
> 
> View attachment 3255125
> 
> 
> 
> 
> 
> REW Rear sub(s) plot:
> 
> 
> View attachment 3255126
> 
> 
> 
> REW Combined plot (Front and Rear):
> 
> View attachment 3255127
> 
> 
> 
> My guess is the nulls are room modes, and perhaps some front sub sbir?
> 
> Am I on the right track here?


I suspect you don’t want six foot deep bass traps, so trapping won’t solve your room modes.

Subwoofer placement looks far from ideal. I may be misreading the photos. Got a diagram?

Assuming you won’t or can’t move the subs, then yes, MSO is going to be your best best.

—-

Separate from bass response, the idea of adding 4” panels (2” plus 2” of air is okay) to tame overall decay times is probably useful (thought at RT60 graph would help confirm how much). 

I would toss a couple on each side wall and a couple on the back wall, and a couple on the ceiling.

Sure Roxul in the speaker columns is helpful, but lower priority. 

—

To tackle sbir you’d need to move the speakers closer to the wall to place the impacted frequency at a range that a four inch panel can manage. There are online calculators that help with the math.


----------



## kalakasan

nathan_h said:


> I suspect you don’t want six foot deep bass traps, so trapping won’t solve your room modes.
> 
> Subwoofer placement looks far from ideal. I may be misreading the photos. Got a diagram?
> 
> Assuming you won’t or can’t move the subs, then yes, MSO is going to be your best best.
> 
> —-
> 
> Separate from bass response, the idea of adding 4” panels (2” plus 2” of air is okay) to tame overall decay times is probably useful (thought at RT60 graph would help confirm how much).
> 
> I would toss a couple on each side wall and a couple on the back wall, and a couple on the ceiling.
> 
> Sure Roxul in the speaker columns is helpful, but lower priority.
> 
> —
> 
> To tackle sbir you’d need to move the speakers closer to the wall to place the impacted frequency at a range that a four inch panel can manage. There are online calculators that help with the math.


Thanks, I’ll get an rt60 graph and room diagram posted soon.
Can you elaborate on your recommendation of absorption over diffusion on the back wall? Also, since my ceilings are low, I’m wondering if 2” panels without a gap would still have a useful effect?


----------



## nathan_h

kalakasan said:


> Can you elaborate on your recommendation of absorption over diffusion on the back wall?


Your back wall is close enough to your seating position that directly behind the seats there is going to be much more benefit to absorption to make the reflections off the back wall less likely to smear the image in my experience. If you want to use diffusion too, that's fine, but I would not place it behind the seats directly but to the sides of the back wall.



kalakasan said:


> Also, since my ceilings are low, I’m wondering if 2” panels without a gap would still have a useful effect?


The short answer is yes, but I would leave 2" air gap if at all possible. It just helps to act less like a tone control and more like a broadband control. That said, sometimes I know it is not possible to place a thicket panel, and I would still rather use a 2" panel than no panel up there.


----------



## kalakasan

nathan_h said:


> Your back wall is close enough to your seating position that directly behind the seats there is going to be much more benefit to absorption to make the reflections off the back wall less likely to smear the image in my experience. If you want to use diffusion too, that's fine, but I would not place it behind the seats directly but to the sides of the back wall.
> 
> 
> 
> The short answer is yes, but I would leave 2" air gap if at all possible. It just helps to act less like a tone control and more like a broadband control. That said, sometimes I know it is not possible to place a thicket panel, and I would still rather use a 2" panel than no panel up there.


Thanks for the explanation. Here's my room layout from REW room sim:










I'm not clear on how to correctly place the subs in REW - I've used the distance from the sub bottom to speaker cone center to derive the speaker elevation, and used the measured depth of the sub (plus spacing from wall) to derive total distance from the wall. Is that correct?


----------



## nathan_h

kalakasan said:


> Thanks for the explanation. Here's my room layout from REW room sim:
> 
> View attachment 3255286
> 
> 
> I'm not clear on how to correctly place the subs in REW - I've used the distance from the sub bottom to speaker cone center to derive the speaker elevation, and used the measured depth of the sub (plus spacing from wall) to derive total distance from the wall. Is that correct?


For the purposes of modeling, using the center of the cone (like the dust cap) is fine. Then doing actual measurements is the key.

But maybe I missed the reason you haven't selected four corners as the placement, or four mid wall positions, or four 1/4 length positions, all of which tend to offer a better starting point.


----------



## kalakasan

The reason for limited sub placement options are the 4 surround speaker columns that project 6” into the room, as well as 2 doors that swing into the room. For reference, see the pics in my first post. I’m also hesitant to ruin the symmetry of the front of the room; however, I could move the right sub towards the corner and place the right speaker on a stand instead - would still look funky though…


----------



## nathan_h

kalakasan said:


> The reason for limited sub placement options are the 4 surround speaker columns that project 6” into the room, as well as 2 doors that swing into the room. For reference, see the pics in my first post. I’m also hesitant to ruin the symmetry of the front of the room; however, I could move the right sub towards the corner and place the right speaker on a stand instead - would still look funky though…


Well, there are some laws of physics that are tough to beat.

Subwoofers: Optimum Number and Locations: https://www.harman.com/documents/multsubs_0.pdf

Audio Engineering Society (AES) Convention Paper 8748: Optimal Configurations for Subwoofers in Rooms Considering Seat to Seat Variation and Low Frequency Efficiency: AES E-Library » Optimal Configurations for Subwoofers in Rooms Considering Seat to Seat Variation and Low Frequency Efficiency

But if you have the stomach, running the multi sub optimizer software which measures each sub and then does hours and hours of math on your computer to figure out the best MiniDSP settings can work wonders.

You won’t be able to run them as two logical subs. To do it’s thing, mso needs to be able to address each sub with unique phase, delay, and eq via a miniDSP. There’s a great thread on it here. And the main web site: Multi-Sub Optimizer Software: Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software

In any event, conventional acoustic treatment and traps won’t solve this situation. Possibly a place like GIK that can do custom tuned membrane traps may be able to do something. It may be worth asking them.

Fun video:


----------



## jdlynch

nathan_h said:


> But maybe I missed the reason you haven't selected four corners as the placement, or four mid wall positions, or four 1/4 length positions, all of which tend to offer a better starting point.


Just so I understand, Wouldn't the positions you mentioned generally apply only to rectangular and sealed rooms?


----------



## nathan_h

That is true and that is what the OP has


----------



## alangsk

*Need Advice on Acoustic Treatments for my Dedicated Theater Room*
So I am at the point where I want to add acoustic treatments to my room. I have a decent amount of absorption already, which I detail out below. My question is if my proposed plan will end up adding too much additional absorption, or if it would be okay.

*Existing Treatment:*
Front Screen Wall:
The front screen wall is a baffle wall with roughly 20 inches of fluffy behind it. There are opening along the top, sides, and bottom to allow bass to be absorbed. In addition there is 1 inch Linacoustic over the baffle wall. See pics below for better understanding.

























Rear of Room:
Rear corners of the room house two of my VBSS subs with fluffy below and above. The sub enclosures are covered with 6 mil plastics to not absorb full frequency. Intent was for it to be more of a bass trap. There are also cutouts in the riser along the rear and rear side walls as well as cutouts below the subs. The riser is stuffed with fluffy. See pics for better understanding.

























Pillars and Proposed Acoustic Plan:
The pillars are filled with cotton fluffy except for the surround speaker locations. See pics of proposed plan below showing the pillars.
Below is my proposed plan for acoustic treatments. I am looking for input on if this is a good plan or if there is too much absorption.
Let me know what additional information may be needed.
_NOTE: The areas shown are general areas and the actual treatments will not cover the entire area._
I will be using 2 inch thick OC703 2x4 foot panels.
*GREEN*: BAD Panels using 1/8th inch hardboard with binary pattern over 2 inch OC703
*RED*: 2 inch thick OC703


----------



## nathan_h

What you have mapped out is probably close to what you want. But don’t forget the ceiling.

Persoanlly I prefer something more like 4” deep panels to impact a broader range of frequencies but measurement will tell you whether you have issues. 

I’d start by measuring the decay time in the room, and add panels in a dispersed manner, in the general locations you describe, and see how they impact that decay time…..and stop adding stuff when you get to something like a consistent .3 ish seconds for the frequencies from the room transition frequency to above 15kHz.


----------



## KyleZY

alangsk said:


> *Need Advice on Acoustic Treatments for my Dedicated Theater Room*
> So I am at the point where I want to add acoustic treatments to my room. I have a decent amount of absorption already, which I detail out below. My question is if my proposed plan will end up adding too much additional absorption, or if it would be okay.
> 
> 
> _NOTE: The areas shown are general areas and the actual treatments will not cover the entire area._
> I will be using 2 inch thick OC703 2x4 foot panels.
> *GREEN*: BAD Panels using 1/8th inch hardboard with binary pattern over 2 inch OC703
> *RED*: 2 inch thick OC703
> View attachment 3259115
> 
> View attachment 3259116
> 
> View attachment 3259117


suggest for the backwall, put some absortion in the center (to absorb the reflection of Center Chanel), others can be BAD panels over OC703. 

by the way, dont't forget the ceiling..


----------



## pigpen33

I am looking to install my first acoustic panels in our basement viewing area. I ordered two for mock up purposes. I"m planning on putting two behind the couch, and two to the left of the main tower speaker and two to the right of the main tower speaker. Are four panels overkill behind the front speakers or is that pretty common? Also, I will have about a four foot gap between the top two panels that will be behind the tower speakers. Would it be too much to put one more panel across the top, basically right above the TV screen?


----------



## nathan_h

pigpen33 said:


> I am looking to install my first acoustic panels in our basement viewing area. I ordered two for mock up purposes. I"m planning on putting two behind the couch, and two to the left of the main tower speaker and two to the right of the main tower speaker. Are four panels overkill behind the front speakers or is that pretty common? Also, I will have about a four foot gap between the top two panels that will be behind the tower speakers. Would it be too much to put one more panel across the top, basically right above the TV screen?
> View attachment 3261980
> View attachment 3261981



The two (or three if you can fit that many) behind the couch are the most important in this room.

Remember to put them low enough that they are below ear height (ie they should be low enough that there is no exposed wall directly behind your head). The one you have hung in the photo looks too high up on the wall.

————

These panels aren’t really thick enough to help with SBIR which is the usual reason people place panels behind the speakers. But they aren’t hurting anything there And they are helping with the overall sound of the room. But that would be the last place I would add more than a couple of panels.

A couple on each side wall is a good call. 

And if you can stomach 4” panels that would be better, especially behind your head. 

I would say adding a couple to the ceiling is useful but I see you have up firing Atmos speakers so maybe not.


----------



## pigpen33

nathan_h said:


> The two (or three if you can fit that many) behind the couch are the most important in this room.
> 
> Remember to put them low enough that they are below ear height (ie they should be low enough that there is no exposed wall directly behind your head). The one you have hung in the photo looks too high up on the wall.
> 
> ————
> 
> These panels aren’t really thick enough to help with SBIR which is the usual reason people place panels behind the speakers. But they aren’t hurting anything there And they are helping with the overall sound of the room. But that would be the last place I would add more than a couple of panels.
> 
> A couple on each side wall is a good call.
> 
> And if you can stomach 4” panels that would be better, especially behind your head.
> 
> I would say adding a couple to the ceiling is useful but I see you have up firing Atmos speakers so maybe not.


Thanks for the response. Everything you said makes sense and I get the feeling you know what your are talking about hehe. I am going to do 3 panels behind the couch now instead of 2 and lower them. In regards to the front speakers, I'm leaning towards dropping down from 2 panels behind each tower to just one. If I were to drop to just one, would you recommend the placement based on my new photos? I did a lower, medium, and higher placement.


----------



## nathan_h

pigpen33 said:


> Thanks for the response. Everything you said makes sense and I get the feeling you know what your are talking about hehe. I am going to do 3 panels behind the couch now instead of 2 and lower them. In regards to the front speakers, I'm leaning towards dropping down from 2 panels behind each tower to just one. If I were to drop to just one, would you recommend the placement based on my new photos? I did a lower, medium, and higher placement.


Low or middle would be my preference. I can't tell how close those speakers are to the wall. Nor how thick the panels are for sure.

But I would surmise that the distance from the FRONT of the speaker to the wall is maybe 20 inches and the panels are probably 2" thick, so we are outside the realm of dealing specifically with boundary re-enforcment (SBIR) issues in this situation. So the specific panel location matters less. 

(If the speakers were closer to the wall, and the panels were at least 4", then they begin to act to kill SBIR issues, and then having hem in the lower position -- maybe just a few inches higher -- would be my choice.)


----------



## rebith75

Hello! I have a mixed use theater room and I am thinking of using panels that I can move in and out as needed. I would like to avoid fiberglass particles being a problem when doing so. Are there any sort of best practices for wrapping? I have looked at the fabrics on ATS acoustics, maybe plastic backing? I have Safe and Sound, or could order OC 703. Thank you.


----------



## nathan_h

rebith75 said:


> Hello! I have a mixed use theater room and I am thinking of using panels that I can move in and out as needed. I would like to avoid fiberglass particles being a problem when doing so. Are there any sort of best practices for wrapping? I have looked at the fabrics on ATS acoustics, maybe plastic backing? I have Safe and Sound, or could order OC 703. Thank you.


I haven't had trouble with the materials from GIK (house brand) though it is kind of sheer and cheaper looking. I have used Guilford of Main and had not trouble. Same with the materials from AcoustiMac.

(Comment: Moving panels gets old real quick. If you can afford to buy material with artwork printed on it, and can leave the panels hung in the room, with pretty pictures on them, that is a much nicer life to live.)

Pre-built: Acoustic Art Panels - GIK Acoustics - Canvas Art that Reduces Noise

DIY: 'DIY Custom-Printed Movie Poster Acoustic Panels - cheap!' Version 2.0 Discussion


----------



## tuskenraider

What is the opinion about using something like the 2 of GIK FreeStand Acoustical panels to create a small wall/reflection point for my left main speaker that has no side boundary? It sits in an open space to my dining room. Will this help even out frequency response? Would doing a 4" panel, be better in this situation? In floorplan pic current panels in red, with "acoustic" curtains red wavy on windows. Included real pic of space as well.


----------



## nathan_h

tuskenraider said:


> What is the opinion about using something like the 2 of GIK FreeStand Acoustical panels to create a small wall/reflection point for my left main speaker that has no side boundary? It sits in an open space to my dining room. Will this help even out frequency response? Would doing a 4" panel, be better in this situation? In floorplan pic current panels in red, with "acoustic" curtains red wavy on windows. Included real pic of space as well.
> View attachment 3269502
> View attachment 3269503


Usually in this situation you would use a panel for the first reflection point of the RIGHT speaker.

The left speaker doesn’t reflect back into the room much. There is no wall on the left.

By absorbing the RIGHT speaker with a panel, it will sound more like the left speaker and give you some acoustic symmetry. (That is, both the left and the right speaker would then have little "reflection" from a side wall. The left speaker because there is no wall. The right speaker, because you have a panel that stops the sound from bouncing off the wall.)

And yes a minimum of 4” of depth is the goal.


----------



## tidwelr1

kalakasan said:


> I've completed REW measurements of my 4 VBSS subs (2 logical) and have some nulls that I'm hoping can be reduced through room treatments first, and then continue with adjustments using a miniDSP HD and possibly MSO. I did an initial subs + center channel 'practice' MSO optimization (3 seat positions) using my REW measurements and the resulting seat-to-seat variance was higher than my liking above 60hz (even with 8 PEQ selected). Moreover, the result after importing the filters into the MiniDSP was disappointing. However, I strongly suspect this it due to user error at some point, so I'm willing to try again.
> 
> Here's the MSO response graph:
> 
> View attachment 3255104
> 
> 
> So while I'm working to get the hang of speaker integration using dsp (if ever!), I've decided to work on applying appropriate room treatments, including bass traps, absorbers/diffusers applied in an aesthetic manner (waf).
> 
> My room:
> 
> 
> 20x15x7'4"
> 'Home theater' double wall construction (except next to concrete basement walls)
> 2 layers of 5/8" drywall with Green Glue - walls and ceiling
> Decoupled walls and ceiling (clips and hat channel)
> 7.4.4 (atmos)
> 
> Speaker Placement is set in stone. My work is to tame the room given those constraints.
> 
> Room Front: MLP is about 8.5' from TV screen.
> 
> View attachment 3255107
> View attachment 3255108
> 
> View attachment 3255109
> 
> 
> 
> A tall bass trap would fit in the left corner
> Would a bass trap under the TV and between the front subs be of any benefit?
> what about a small bass trap in the space on the right (only sub height)?
> 
> Room Rear:
> 
> View attachment 3255110
> View attachment 3255111
> 
> 
> View attachment 3255112
> 
> 
> Room Rear:
> 
> 
> Bass trap would fit in left corner
> A diffuser would fit on the back wall
> Bottom of speaker columns are hollow - fill with roxel?
> 
> Room Walls:
> 
> - 2" Absorbers at first reflection points (2" offset from wall)
> 
> REW Front sub(s) plot:
> 
> View attachment 3255125
> 
> 
> 
> 
> 
> REW Rear sub(s) plot:
> 
> 
> View attachment 3255126
> 
> 
> 
> REW Combined plot (Front and Rear):
> 
> View attachment 3255127
> 
> 
> 
> My guess is the nulls are room modes, and perhaps some front sub sbir?
> 
> Am I on the right track here?


Your room is screaming for a projector setup with the speakers behind the screen. You have everything else in place aside from room treatment. 


Sent from my iPhone using Tapatalk


----------



## tuskenraider

nathan_h said:


> Usually in this situation you would use a panel for the first reflection point of the RIGHT speaker.
> 
> The left speaker doesn’t reflect back into the room much. There is no wall on the left.
> 
> By absorbing the RIGHT speaker with a panel, it will sound more like the left speaker and give you some acoustic symmetry. (That is, both the left and the right speaker would then have little "reflection" from a side wall. The left speaker because there is no wall. The right speaker, because you have a panel that stops the sound from bouncing off the wall.)
> 
> And yes a minimum of 4” of depth is the goal.


Hmm, clearly I haven't a clue. Do these measurements give any insight on how any further treatment may help? This is without the Yamaha YPAO room correction, which helps smooth things out a little. The huge dip of the left speaker seems to be the biggest flaw. My placement of 4" panels clearly have helped audibly with echo, but measurement-wise, is still a mess. I also included a pic of the back wall panels if that helps anything. Thanks again.


----------



## nathan_h

tuskenraider said:


> Hmm, clearly I haven't a clue. Do these measurements give any insight on how any further treatment may help? This is without the Yamaha YPAO room correction, which helps smooth things out a little. The huge dip of the left speaker seems to be the biggest flaw. My placement of 4" panels clearly have helped audibly with echo, but measurement-wise, is still a mess. I also included a pic of the back wall panels if that helps anything. Thanks again.
> View attachment 3269982
> View attachment 3269975



Glad to see you have panels behind you. That helps a lot to clean up the sound in the room, in general. You won't see much in the frequency response graphs to represent this. The benefit of those panels is far more likely to show up in the decay time graphs, and reverberation time graphs. Based on what I see in the room, I'll bet those decay time graphs look great -- and that is why the room sounds better to you. Kudos. In fact, unless you are eager to dive down a rabbit hole, I wouldn't worry about measuring decay time in this room any more. I would bet you a six pack of premium beer you have achieved a reverberation time of half a second or less, which is the goal.

--

That dip at 60 hertz in the left looks ugly. It may not sound ugly. But: Here is what I would do, regardless: 

Configure both L and R speaker as "small" in your AVR. Cross over both the L and R speaker to the subwoofer at 80 hz. The response at 60hz basically won't matter any longer. 

I don't know which version of YPAO you have, but hopefully its a version that includes equalization of the subwoofer. Assuming you are using a single subwoofer, you'll only be able to get great response at one seat, but often that's enough since the rest of the household doesn't really care.


----------



## tuskenraider

nathan_h said:


> That dip at 60 hertz in the left looks ugly. It may not sound ugly. But: Here is what I would do, regardless:
> 
> Configure both L and R speaker as "small" in your AVR. Cross over both the L and R speaker to the subwoofer at 80 hz. The response at 60hz basically won't matter any longer.
> 
> I don't know which version of YPAO you have, but hopefully its a version that includes equalization of the subwoofer. Assuming you are using a single subwoofer, you'll only be able to get great response at one seat, but often that's enough since the rest of the household doesn't really care.


I won't post more graphs, but yes, my decay times look great. I may have tried 80hz crossover on my mains, but maybe not. Hard to stomach doing that with a nice set of towers. Nonetheless, they are currently crossed over at 40hz, I believe 60hz measure worse, and I maaay not have tried 80hz. Guess I'll measure. I have the RX-A3080, so Yamaha's best YPAO. Dual subs may be in the future, but this SVS PB2+ has been going strong for 18 years, kinda want to ride it out to its death. Shame all the used ones have been far away, cause they're fairly cheap now and a pair would be nice. Likely move on to a pair of Rythmik 15's. Really appreciate the feedback.


----------



## nathan_h

tuskenraider said:


> I won't post more graphs, but yes, my decay times look great. I may have tried 80hz crossover on my mains, but maybe not. Hard to stomach doing that with a nice set of towers. Nonetheless, they are currently crossed over at 40hz, I believe 60hz measure worse, and I maaay not have tried 80hz. Guess I'll measure. I have the RX-A3080, so Yamaha's best YPAO. Dual subs may be in the future, but this SVS PB2+ has been going strong for 18 years, kinda want to ride it out to its death. Shame all the used ones have been far away, cause they're fairly cheap now and a pair would be nice. Likely move on to a pair of Rythmik 15's. Really appreciate the feedback.


Sounds good. We're getting pretty far off topic, so I'll just say that the best place for bass response in a room is seldom the best place for treble response. And bass response is much easier to manage in a single subwoofer (or dual mono subwoofers when set up correctly), anyway.

I know it seems crazy to cross over towers at 80 hz. But it really does work better most of the time. Or even higher! Sometimes, even though the L and R can play fine at 80 hz, the in room response is better when crossing over to the sub at 90 or 100 hz. REW measurements can be very useful in this regard.

HT Gurus videos on YouTube can be very helpful in this regard. (He gets fancy with dual subs and using a miniDSP and those are all fine approaches, and you may go down that path at some point, but I would direct you do his videos about measuring response at the crossover to find the best crossover point, setting subwoofer distance for the best acoustic response, and similar.)


----------



## KitemanDan

i'm sure these have been asked, but having tough time finding the answer:

(1) It appears that FRK/FSK and kraft paper and maybe even thick plastic film (3-6mil) are acceptable facings for OC703 to reflect high frequencies. If thin plastic is preferable to the other two, why is it that FRK/FSK appears to be the industry standard? I can face my panels with plain old kraft paper for 1/4 the cost of using FRK/FSK. With that said, are there any advantages to using FRK/FSK proper? I'm just curious as to why FRK/FSK is the standard when several cheaper alternatives can be readily had. 

(2) I've seen the FRK applied in 3" strips spaced 3" apart. why 3" on, 3" off? I've seen a number of theaters do that, like there is something special about 3"... why not just cover 100%, or every 2", or 50% on 50% off... Is there magic in 3"?


----------



## Rambler75

Hello! I have a local who has Vicoustic products available for a really good price, I am trying to figure out if they would make sense for my space. 

My room is 14' X 18' with vaulted ceiling 8' high on left side up to 11' high on right side. Room opens up to hallway and kitchen on back right of room. Use is primarily movies.

Current treatment (panels are all absorption):
Ceiling: Two 2'X4' panels between MLP and speakers
High wall: One 2'X4' panel high up and one 2'x4' panel to treat first reflection from opposite main speaker
Low wall: One 2'X4' panel to treat first reflection from opposite main speaker
Back wall: Two 2'X4' panels

The Vicoustic products available are the A75 and Vari panel





Vicoustic - Pol A75 - Home Cinema at Vision Hifi


Acoustic Panels | Buy Flexi Pol A75 Acoustic panels from Vision Hifi. Australia's Number 1. Audio Visual Specialists.




www.visionhifi.com.au









Vari Panel Kit Light Brown


Innovative soundproofing company specializing in acoustic treatments. Explore our acoustic solutions: acoustic panels, studio foam, bass traps & more!




vicousticna.com





I am thinking my next step would be some form of diffusion. Neither of these Vicoustic products are diffusion primarily, but both seem to have some reflection to maintain "ambiance." I was thinking I could put them high up on back wall, on ceiling behind MLP, or next to absorption closer to screen wall. I know a lot of this stuff is subjective, but just trying to figure out if I should just pass on this stuff, or grab it and make it work (limited budget). 

Thank you!


----------



## nathan_h

Rambler75 said:


> Hello! I have a local who has Vicoustic products available for a really good price, I am trying to figure out if they would make sense for my space.
> 
> My room is 14' X 18' with vaulted ceiling 8' high on left side up to 11' high on right side. Room opens up to hallway and kitchen on back right of room. Use is primarily movies.
> 
> Current treatment (panels are all absorption):
> Ceiling: Two 2'X4' panels between MLP and speakers
> High wall: One 2'X4' panel high up and one 2'x4' panel to treat first reflection from opposite main speaker
> Low wall: One 2'X4' panel to treat first reflection from opposite main speaker
> Back wall: Two 2'X4' panels
> 
> The Vicoustic products available are the A75 and Vari panel
> 
> 
> 
> 
> 
> Vicoustic - Pol A75 - Home Cinema at Vision Hifi
> 
> 
> Acoustic Panels | Buy Flexi Pol A75 Acoustic panels from Vision Hifi. Australia's Number 1. Audio Visual Specialists.
> 
> 
> 
> 
> www.visionhifi.com.au
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Vari Panel Kit Light Brown
> 
> 
> Innovative soundproofing company specializing in acoustic treatments. Explore our acoustic solutions: acoustic panels, studio foam, bass traps & more!
> 
> 
> 
> 
> vicousticna.com
> 
> 
> 
> 
> 
> I am thinking my next step would be some form of diffusion. Neither of these Vicoustic products are diffusion primarily, but both seem to have some reflection to maintain "ambiance." I was thinking I could put them high up on back wall, on ceiling behind MLP, or next to absorption closer to screen wall. I know a lot of this stuff is subjective, but just trying to figure out if I should just pass on this stuff, or grab it and make it work (limited budget).
> 
> Thank you!


Hard to know whether diffusion is useful for you, based on this info.

Do you have photos of the room?

I would, in general, suspect that you don't need diffusion unless the room has no furniture.... (other than your seating of course). But maybe there is something you can hear that makes you think diffusion is needed?

---

Sounds like you have some good placement of absorption panels. Assuming they are four inches in depth, they should be doing some good stuff. If they are more shallow than that, i would look into using spacers to give them more of an air gap, to increase the range of frequencies they impact. That would be the upgrade I would look at.

---

And of course if you want to get into the nuances, measuring your room with REW (free) using a calibrated mic (c $100) is a useful tool to help decide what to do, if anything.


----------



## Rambler75

The room is a mixed use room, with 4 different chairs, end tables, in the rear is a closet that is open (for the projector to shoot out of). Yes, the absorption panels are 4" and I am I have REW and mic. 

I don't have a good picture right now because I tore down my front wall recently to redo some things. I honestly don't know if I need diffusion necessarily, just that the Vicoustic products seemed to be a good deal and I was on the fence to grab it.


----------



## nathan_h

Rambler75 said:


> The room is a mixed use room, with 4 different chairs, end tables, in the rear is a closet that is open (for the projector to shoot out of). Yes, the absorption panels are 4" and I am I have REW and mic.
> 
> I don't have a good picture right now because I tore down my front wall recently to redo some things. I honestly don't know if I need diffusion necessarily, just that the Vicoustic products seemed to be a good deal and I was on the fence to grab it.


While I can't confirm with my own ears, nor guess with a photo of the room, from what you describe, the bargain here is that you don't need to spend any money on diffusion based on all the available information.


----------



## Rambler75

Here are some older pictures, befire adding absorption panels, but can give you an idea of the room. Also, that sub is no longer in the closet.


----------



## nathan_h

Rambler75 said:


> Here are some older pictures, befire adding absorption panels, but can give you an idea of the room. Also, that sub is no longer in the closet.


Yeah, if you didn't already have absorption, I'd be saying you should get some!

I find it somewhat unlikely you will benefit much from diffusion. If you have money to spend on improving things, we can talk about how dual subs might really do something nice for consistent bass in there. (I mean, that's a different thread, probably, but that is what I would explore.)


----------



## Rambler75

I've got four 18" behind the false wall. You think I could be on this forum and not have too much bass?


----------



## bwr827

Here’s my plan - critiques welcome. I’ve picked Rockwool comfort board because it’s available nearby and has some rigidity for ease of installation. 

*Room details:*

10.5’ wide by 18’ long in basement 
136” 16:9 spandex screen
Carpeted floor
21” deep cavity behind screen, with LCR and subwoofer
Finished drywall on all walls including behind screen
Unfinished ceiling (for next 1-2 years)
*Sound absorption:*

Behind screen: 1.5” Rockwool comfort board (full coverage)
Side walls: 1.5” Rockwool comfort board panels wrapped in spandex at first reflection points
Ceiling: 1.5” Rockwool comfort board horizontally at first reflection point
*Next steps: *see how things sound and try more ideas…

So, good plan? Terrible plan? A place to start?


----------



## sdurani

bwr827 said:


> Here’s my plan - critiques welcome. I’ve picked Rockwool comfort board because it’s available nearby and has some rigidity for ease of installation.


Comfortboard 80 needs at least 3" of thickness to get close to broadband absorption down to the subwoofer range. 









The problem with using absorption panels that are too thin is that they end up becoming unintended tone controls, like turning down the treble knob because you're absorbing mostly mids and highs.


----------



## lavakv

bwr827 said:


> Here’s my plan - critiques welcome. I’ve picked Rockwool comfort board because it’s available nearby and has some rigidity for ease of installation.
> 
> *Room details:*
> 
> 10.5’ wide by 18’ long in basement
> 136” 16:9 spandex screen
> Carpeted floor
> 21” deep cavity behind screen, with LCR and subwoofer
> Finished drywall on all walls including behind screen
> Unfinished ceiling (for next 1-2 years)
> *Sound absorption:*
> 
> Behind screen: 1.5” Rockwool comfort board (full coverage)
> Side walls: 1.5” Rockwool comfort board panels wrapped in spandex at first reflection points
> Ceiling: 1.5” Rockwool comfort board horizontally at first reflection point
> *Next steps: *see how things sound and try more ideas…
> 
> So, good plan? Terrible plan? A place to start?


The hidden 21" depth behind your screen offers the opportunity to create significant, and relatively cheap (because it can be ugly) bass trapping. I would stuff the entirety of that volume with R38 and for your "next steps" face it as desired if you'd prefer less high end absorption across the front soundstage (look around for some screenshots of professional plans which create partial baffle walls around LCR for example). 

I did the same and would say it was easily the most impactful change to audio quality I've experienced from a single treatment change. Obviously significant low end ringing improvement but also vastly improved front stage coherence/panning/dialog intelligibility/etc.

See below for approximations of absorption coefficients for the theoretical 21" thick R38 (blue line, absorber 1) and the 1.5" rockwool on the wall (green line, absorber 2, educated guess at resistivity). No contest.


----------



## bwr827

lavakv said:


> The hidden 21" depth behind your screen offers the opportunity to create significant, and relatively cheap (because it can be ugly) bass trapping. I would stuff the entirety of that volume with R38 and for your "next steps" face it as desired if you'd prefer less high end absorption across the front soundstage (look around for some screenshots of professional plans which create partial baffle walls around LCR for example).
> 
> I did the same and would say it was easily the most impactful change to audio quality I've experienced from a single treatment change. Obviously significant low end ringing improvement but also vastly improved front stage coherence/panning/dialog intelligibility/etc.


Appreciate your thoughts! When you say you "did the same" do you mean filling your cavity entirely with fiberglass, or the combo of filling the cavity as well as building a partial baffle wall?

Correct me, but don't my LCR and sub need some breathing room around them? If I stuff the entire cavity with fiberglass, I won't have room for the equipment.

Locally I can buy R40 "next gen" fiberglass by Owens Corning, which is 11" thick. If I lined the cavity with that, with one batt on each side/end, and one layer of batting across the front wall, would that be sufficient?

Here's an image of the wall cavity and framing (ignore the ceiling light, it's gone now):


----------



## lavakv

bwr827 said:


> Appreciate your thoughts! When you say you "did the same" do you mean filling your cavity entirely with fiberglass, or the combo of filling the cavity as well as building a partial baffle wall?


I packed fiberglass around/behind/below/above my old LCR towers and the sub which sits behind the screen and measured (primarily low end) and observed (primarily high end) vast improvement over the modest foam and insulation I had on the wall behind them previously. I had some plans for partial baffles but wound up upgrading to speakers large enough that the cabinets themselves form a baffle with very little gap or fiberglass facing the screen.


bwr827 said:


> Correct me, but don't my LCR and sub need some breathing room around them? If I stuff the entire cavity with fiberglass, I won't have room for the equipment.


Ports on the LCR and sub would certainly need free space in front of them, but space around cabinets just invite unwanted SBIR, etc. I had set up the equipment then "cut and pasted" the batts to pack the volume.


bwr827 said:


> Locally I can buy R40 "next gen" fiberglass by Owens Corning, which is 11" thick. If I lined the cavity with that, with one batt on each side/end, and one layer of batting across the front wall, would that be sufficient?


Mounting the 11" R40 on the wall does (obviously) decrease the low end effectiveness compared to a 21" thick layer. See green below.









However, you've unlocked a cost saving secret! The single layer of 11" thick R40 with a 10" air gap (modeled in green below) offers very similar performance with lower volume ($) of material compared to the full 21" thickness (blue below). That said, suspending the batts to form a wall while maintaining the air gap takes a bit of patience and once you start getting itchy just packing the volume may become attractive! I'm seeing 24" wide x 48" tall x 11" thick batts of that R40 available in Canada, so you could alternatively pack such that the 24" dimension (squashed a bit) orients from wall to screen face with your 21" false wall depth.









My other amateur opinions stem from the screen width almost matching room width:

the left and right being (I assume) just about corner loaded will make this bass trapping more important, along with fine tuning toe-in critical
you may also benefit from diffusion (look up BAD panels for diffusion on the cheap) as I think I would want some more (good) energy from the walls to increase perceived width (assuming decent off-axis performance of LCR)


----------



## nathan_h

bwr827 said:


> Here’s my plan - critiques welcome. I’ve picked Rockwool comfort board because it’s available nearby and has some rigidity for ease of installation.
> 
> *Room details:*
> 
> 10.5’ wide by 18’ long in basement
> 136” 16:9 spandex screen
> Carpeted floor
> 21” deep cavity behind screen, with LCR and subwoofer
> Finished drywall on all walls including behind screen
> Unfinished ceiling (for next 1-2 years)
> *Sound absorption:*
> 
> Behind screen: 1.5” Rockwool comfort board (full coverage)
> Side walls: 1.5” Rockwool comfort board panels wrapped in spandex at first reflection points
> Ceiling: 1.5” Rockwool comfort board horizontally at first reflection point
> *Next steps: *see how things sound and try more ideas…
> 
> So, good plan? Terrible plan? A place to start?





sdurani said:


> Comfortboard 80 needs at least 3" of thickness to get close to broadband absorption down to the subwoofer range.
> View attachment 3284390
> 
> 
> The problem with using absorption panels that are too thin is that they end up becoming unintended tone controls, like turning down the treble knob because you're absorbing mostly mids and highs.





lavakv said:


> The hidden 21" depth behind your screen offers the opportunity to create significant, and relatively cheap (because it can be ugly) bass trapping. I would stuff the entirety of that volume with R38 and for your "next steps" face it as desired if you'd prefer less high end absorption across the front soundstage (look around for some screenshots of professional plans which create partial baffle walls around LCR for example).
> 
> I did the same and would say it was easily the most impactful change to audio quality I've experienced from a single treatment change. Obviously significant low end ringing improvement but also vastly improved front stage coherence/panning/dialog intelligibility/etc.
> 
> See below for approximations of absorption coefficients for the theoretical 21" thick R38 (blue line, absorber 1) and the 1.5" rockwool on the wall (green line, absorber 2, educated guess at resistivity). No contest.
> View attachment 3284394


@bwr827 listen to these two posts. They are 100% right. 

I would go so far as to say that if you have space for a 3" panel in the room, try to make it 1" off the wall, which will help get into the lower frequencies even better.


----------



## squared80

I had initially planned on using all my Rockwool 60 panels to cover my front stage and center of my back wall (all 4" thick with 2" gap), and then as corner bass traps.

I was also going to use them as 2" think panels for first reflection points on my walls and ceilings, too, but I have a bunch of pink fluffy leftover. Should I use pink fluffy for my first reflection points instead? Or should I go ahead and just use the Rockwool 60 panels?


----------



## nathan_h

squared80 said:


> I had initially planned on using all my Rockwool 60 panels to cover my front stage and center of my back wall (all 4" thick with 2" gap), and then as corner bass traps.
> 
> I was also going to use them as 2" think panels for first reflection points on my walls and ceilings, too, but I have a bunch of pink fluffy leftover. Should I use pink fluffy for my first reflection points instead? Or should I go ahead and just use the Rockwool 60 panels?


You are doing a false wall for the screen, right? If so, piling pink fluffy back there is a great approach, more cost effective than rockwool panels and does much better at trapping bass. Basically, just fill the whole area behind the screen. 

I wouldn't try to use fluffy stuff for panels on the wall in the room. Too flimsy. Use the Rockwool for panels in the room. If you can do 4" panels instead of 2" panels, you'll likely be much happier. 2" panels trap the treble but leave the rest untouched. But for consistent sound, you want to trap everything in the frequency range if possible. A thicker panel does that much better.


----------



## squared80

nathan_h said:


> You are doing a false wall for the screen, right? If so, piling pink fluffy back there is a great approach, more cost effective than rockwool panels and does much better at trapping bass. Basically, just fill the whole area behind the screen.
> 
> I wouldn't try to use fluffy stuff for panels on the wall in the room. Too flimsy. Use the Rockwool for panels in the room. If you can do 4" panels instead of 2" panels, you'll likely be much happier. 2" panels trap the treble but leave the rest untouched. But for consistent sound, you want to trap everything in the frequency range if possible. A thicker panel does that much better.


Yes, false wall. About 48" of space back there. All my plans have, from the beginning, been based on Rockwool 60 for the front stage. But as I've gotten closer to that point in my build, I've been looking into it more and although using it for corner bass traps in the front might still be the way to go, I've read in a few places now that pink fluffy > Rockwool 60 for the front treatments, due to it's higher frequency absorption coefficient, I assume.

But how much pink fluffy would I need? I can cover all the walls and ceiling behind the screen with 3.5", but are you saying I should basically be filling it as full as I can with the stuff?


----------



## nathan_h

Yes basically stack batts and fill all four feet other than the speakers and subs of course! It will be an awesome bass trap. Use the cheapest batts you can find. They are all extremely similar.


----------



## bwr827

When you stack a bunch of fibreglass behind the screen, are you then covering it with fabric to contain fibers?

I have a partial back wall behind 2/3 of the seating. Are similar 4” deep panels recommended back there, or is that a spot where a more treble-focused application is suitable?


----------



## nathan_h

Yes, personally, I cover it with jute or similar fabric, but many people have enough of a fabric "wall" (the false wall for the screen) that they don't feel the need. 

Personally, I always use a 4" or deeper panel anywhere that I use a panel. There is no place where I want to have an imbalance in frequency response.


----------



## flyers10

nathan_h said:


> Yes basically stack batts and fill all four feet other than the speakers and subs of course! It will be an awesome bass trap. Use the cheapest batts you can find. They are all extremely similar.


Where does the use of Linacoustic come into play here?


----------



## nathan_h

That would be for a baffle wall construction like this:










But I presume the OP is talking about something like this:










based on the description of having four feet of space behind the screen.

People used to leave the space open, adding thin treatment like linacoustic behind the freestanding speakers, but it didn’t kill sbir and missed out on easy cheap and effective bass trapping.


----------



## squared80

But if we're talking about _bass trapping_, Rockwool 60 would be somewhat more effective than pink fluffy. *Isn't treating the front stage more about dealing with higher frequency reflections than it is about bass trapping?*

I have the two options. Cover the entire front stage with 4" of Rockwool 60 with a 2" gap, or cover the entire front stage with 3.5" of pink fluffy and put a bunch of Rockwool 60 in the corners. Which would be more effective and a better use of materials?


----------



## fattire

squared80 said:


> *Isn't treating the front stage more about dealing with higher frequency reflections than it is about bass trapping?*


It's both if you have the option. Most people don't due to the depth of material required.

Have a look at the results on this thread: mikela's SBA/Trinnov Theater Build. That's an SBA but the physics on the front wall are the same as the physics on the back wall.


----------



## nathan_h

squared80 said:


> But if we're talking about _bass trapping_, Rockwool 60 would be somewhat more effective than pink fluffy. *Isn't treating the front stage more about dealing with higher frequency reflections than it is about bass trapping?*
> 
> I have the two options. Cover the entire front stage with 4" of Rockwool 60 with a 2" gap, or cover the entire front stage with 3.5" of pink fluffy and put a bunch of Rockwool 60 in the corners. Which would be more effective and a better use of materials?


Sorry I thought you have FOUR FEET behind your screen. I apologize. 

As @fattire noted, bass trapping can happen anywhere in a room. If there is a large space behind the screen, filling that with insulation (cheapest fiberglass or rockwool you find is fine) to a depth of a few feet is super helpful for trapping bass. 

But if sounds like you have just a few INCHES between screen and the wall of the room. In that case, the thickest panels you can fit are going to be helpful. And if you have more space in the corners, put more stuff there.


----------



## squared80

nathan_h said:


> Sorry I thought you have FOUR FEET behind your screen. I apologize.
> 
> As @fattire noted, bass trapping can happen anywhere in a room. If there is a large space behind the screen, filling that with insulation (cheapest fiberglass or rockwool you find is fine) to a depth of a few feet is super helpful for trapping bass.
> 
> But if sounds like you have just a few INCHES between screen and the wall of the room. In that case, the thickest panels you can fit are going to be helpful. And if you have more space in the corners, put more stuff there.


No, it's 4 feet. I don't have enough pink fluffy to fill a 10x8x4 cavity, which is why I was either going to just maintain my plan to use all Rockwool, OR I could line the walls and ceiling with 3.5" of pink fluffy and throw the Rockwool in the corners. If the latter gets me the same effect on my front stage as covering all of it with the Rockwool panels, I'd prefer to do that and utilize my Rockwool panels elsewhere in the room, like for thicker bass traps in other corners.


----------



## flyers10

squared80 said:


> No, it's 4 feet. I don't have enough pink fluffy to fill a 10x8x4 cavity, which is why I was either going to just maintain my plan to use all Rockwool, OR I could line the walls and ceiling with 3.5" of pink fluffy and throw the Rockwool in the corners. If the latter gets me the same effect on my front stage as covering all of it with the Rockwool panels, I'd prefer to do that and utilize my Rockwool panels elsewhere in the room, like for thicker bass traps in other corners.


I'd get more pink fluffy and let that 4' depth work for you. It's not super expensive.


----------



## nathan_h

Well 3.5" of fluffy stuff is okay, not quite as good as four inches of rockwool, but same general vicinity. 

But it's a wasted opportunity. 

Go spend a hundred bucks at home depot and pile that space full of pink fluffy batts! 

EDIT: I see that @flyers10 had the same thought. Yep, agree 100%.


----------



## squared80

Got it. But man, surrounding my RF-7 III's with fiberglass insulation... I think that's illegal in like 30 states (at least it should be).


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## newoski

I’m not handy. 
Any tool recommendations for straight cuts on 4x10ft duct board? I’m thinking a T-Square and razor, but would love something like a double sided T-Square that can hold onto both sides to ensure a straight cut… just not sure if such a thing exists


----------



## obico

Does insulation behind a standard 12.5mm plasterboard make a difference in acoustics of the room?
I’m asking because:
1. I have an attic where everything is drywall with insulation stuffed behind it. The room is very “dead”, with zero slap echo (did not measure though).
2. I have a small false ceiling “island” on the concrete ceiling of my media room, and I’m looking for options to use it as acoustic treatment for the room. It has a good 15cm cavity inside, and I could also attack some of the first reflection point.
Any hint is highly appreciated!


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## nathan_h

Insulation:

Behind drywall (ie, outside the room) there is very very little impact on the sound in the room. 

On the other hand, when inside the room, behind fabric, can help reduce reflections and decay time.


----------



## squared80

Been spending a lot of time figuring out how I want to build my acoustic panels. For some, I think I'll get some decorative movie prints (what a great thread, by the way). But I was also looking at a couple panels that I could DIY that look like those GIK panels. I don't have the tools to make my own, but I found some panels at Home Depot for like $40 each. Quite a few options; not sure if anyone had used these in their own build or not. They are 2'x4'.


























'DIY Custom-Printed Movie Poster Acoustic Panels -...


Hi all. I'm very interested in making acoustic treatments with these types of prints, but I am concerned about potential acoustic issues. I don't want to compromise on acoustics and for this reason I've been leaning towards using speaker fabrics, but these are ugly. Data shows that many fabrics...




www.avsforum.com


----------



## NotShorty

squared80 said:


> Been spending a lot of time figuring out how I want to build my acoustic panels. For some, I think I'll get some decorative movie prints (what a great thread, by the way). But I was also looking at a couple panels that I could DIY that look like those GIK panels. I don't have the tools to make my own, but I found some panels at Home Depot for like $40 each. Quite a few options; not sure if anyone had used these in their own build or not. They are 2'x4'.
> 
> View attachment 3289504
> 
> View attachment 3289505
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 'DIY Custom-Printed Movie Poster Acoustic Panels -...
> 
> 
> Hi all. I'm very interested in making acoustic treatments with these types of prints, but I am concerned about potential acoustic issues. I don't want to compromise on acoustics and for this reason I've been leaning towards using speaker fabrics, but these are ugly. Data shows that many fabrics...
> 
> 
> 
> 
> www.avsforum.com


Are you looking for diffusion panels or plates to put over your absorbers that make them into diff-sorbers?

I stumbled across this page after following a different link (Jeff Parkinson was explaining why you want your front wall treated - to reduce SBIR) and began contemplating whether DIY diffusion panels were something I could tackle. Unfortunately the link to the free blueprints is broken and the author hasn't responded to my email yet. A few people on the forums have made these panels, but they're not talked about a lot.

Anyway, sorry to hijack your thread, especially if it's totally irrelevant to your needs. I just bought a few boxes of rigid fiberglass panels and hope to start tackling my acoustic treatments (including diffusers) over the summer.


----------



## BBB_63

Hey, gang..anyone able to advise on whether having an angled rear wall (45 degrees or so, roughly to the L-R midpoint of the connecting wall) would give us issues with acoustics?

Pic below..the inside edges of the boxes indicate how the rear walls would potentially be built. Reason I'd angle the rightmost (as you're facing the rear of the room) half or so is because we want to keep the window shown on the right side of the pic outside of the Theater. The only other way we could do that involves moving the wall toward the front of the room 5' or so and building straight across, and that just really limits the length of the room to the point it no longer feels like a theater but just a tiny room with a big screen on the wall. 





  








Angled Wall




__
BBB_63


__
7 mo ago




Potential rear wall






Room length with the angled wall is about 23'. Room length with a straight wall is about 17 and a half ft. I plan to have a false wall and AT screen again, so that takes another 2'4 out. Then, if I bring the chairs roughly 2' from the back wall (which as I understand it is recommended for better acoustics), the back of our chairs wind up at around 12' - which is really sub-optimal. And we can only fit 1 row. On the other hand, if I use the angled wall approach, 2 rows fit comfortably. I'd most likely make the back row 2 seats (on riser) and the front 3 seats, so that I can keep the back row as far from that wonky angled wall as possible..and the more width to the back row, the closer to the angled wall (and possibly crazy acoustic issues) I'd get..

Doorway would be on the far left rear corner, where the one silver chair currently is. The 2 brown chairs in the center of the pic are to show where the rear row of seats would (roughly) go. I haven't yet checked width of seats we'd likely use, so not sure how close to the angled wall I'd get. Or is that even an issue if we DO get too close to it - say, if I used 3 seats instead of 2 in that row?

Would appreciate any and all input on this as I'm not sure what issues we'd run into with an angled vs. straight wall - though the angled sure gives us more seating options.

Thanks..


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## nathan_h

I’ve heard of people using those decorative sheets from Home Depot on top of a traditional absorption panel. Basically it reduces the amount of absorption (esp high frequency) and looks cool. Regardless of what people call them I think it’s not conventional diffusion as that term is used in acoustics. But that’s okay. Getting decay time right is mostly about absorption. 


squared80 said:


> Been spending a lot of time figuring out how I want to build my acoustic panels. For some, I think I'll get some decorative movie prints (what a great thread, by the way). But I was also looking at a couple panels that I could DIY that look like those GIK panels. I don't have the tools to make my own, but I found some panels at Home Depot for like $40 each. Quite a few options; not sure if anyone had used these in their own build or not. They are 2'x4'.
> 
> View attachment 3289504
> 
> View attachment 3289505
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 'DIY Custom-Printed Movie Poster Acoustic Panels -...
> 
> 
> Hi all. I'm very interested in making acoustic treatments with these types of prints, but I am concerned about potential acoustic issues. I don't want to compromise on acoustics and for this reason I've been leaning towards using speaker fabrics, but these are ugly. Data shows that many fabrics...
> 
> 
> 
> 
> www.avsforum.com


----------



## nathan_h

BBB_63 said:


> Hey, gang..anyone able to advise on whether having an angled rear wall (45 degrees or so, roughly to the L-R midpoint of the connecting wall) would give us issues with acoustics?
> 
> Pic below..the inside edges of the boxes indicate how the rear walls would potentially be built. Reason I'd angle the rightmost (as you're facing the rear of the room) half or so is because we want to keep the window shown on the right side of the pic outside of the Theater. The only other way we could do that involves moving the wall toward the front of the room 5' or so and building straight across, and that just really limits the length of the room to the point it no longer feels like a theater but just a tiny room with a big screen on the wall.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Angled Wall
> 
> 
> 
> 
> __
> BBB_63
> 
> 
> __
> 7 mo ago
> 
> 
> 
> 
> Potential rear wall
> 
> 
> 
> 
> 
> 
> Room length with the angled wall is about 23'. Room length with a straight wall is about 17 and a half ft. I plan to have a false wall and AT screen again, so that takes another 2'4 out. Then, if I bring the chairs roughly 2' from the back wall (which as I understand it is recommended for better acoustics), the back of our chairs wind up at around 12' - which is really sub-optimal. And we can only fit 1 row. On the other hand, if I use the angled wall approach, 2 rows fit comfortably. I'd most likely make the back row 2 seats (on riser) and the front 3 seats, so that I can keep the back row as far from that wonky angled wall as possible..and the more width to the back row, the closer to the angled wall (and possibly crazy acoustic issues) I'd get..
> 
> Doorway would be on the far left rear corner, where the one silver chair currently is. The 2 brown chairs in the center of the pic are to show where the rear row of seats would (roughly) go. I haven't yet checked width of seats we'd likely use, so not sure how close to the angled wall I'd get. Or is that even an issue if we DO get too close to it - say, if I used 3 seats instead of 2 in that row?
> 
> Would appreciate any and all input on this as I'm not sure what issues we'd run into with an angled vs. straight wall - though the angled sure gives us more seating options.
> 
> Thanks..


That window won’t be of much use outside the theater room like that. It will just be a lighted up cavity in the exterior room. The angle is such you probably won’t be able to see out of it. I can’t see the point. It’s ad for the theater and ba for the room outside the theater. 

So, what are you trying to achieve by preserving it?

tldr, a rectangular room is easier to manage. 

If you need two rows of seats, you would be well advised to cover the window to build a rectangular room. It doesn’t have to be a big construction project. 

If you need one row of seats, just make the theater smaller If you really need a window nook in the room outside the theater. 

The angled wall won’t be the end of the world but it will make acoustics more challenging. If that is your only choice, go for it.


----------



## fattire

@BBB_63 You also don't necessarily need to do a major construction project and fully remove the window. I have the same issue in my theater room and plan to address one or two of the windows using removable window plugs. Roger Dressler here on the forum has a great example in his build thread.

I like his solution because there aren't any holes or permanent modifications, and they are quickly removable in the event of an emergency. As he mentions, light is easy to address, but his solution also helps mitigate sound as well. My windows appear to be wider than his, so I may build two plugs per window so they are easier to handle (thinking more in an emergency situation). His design, though, is dead simple which makes it easy to tweak/modify.


----------



## BBB_63

fattire said:


> @BBB_63 You also don't necessarily need to do a major construction project and fully remove the window. I have the same issue in my theater room and plan to address one or two of the windows using removable window plugs. Roger Dressler here on the forum has a great example in his build thread.
> 
> I like his solution because there aren't any holes or permanent modifications, and they are quickly removable in the event of an emergency. As he mentions, light is easy to address, but his solution also helps mitigate sound as well. My windows appear to be wider than his, so I may build two plugs per window so they are easier to handle (thinking more in an emergency situation). His design, though, is dead simple which makes it easy to tweak/modify.


Thanks..I was aware of window plugs and if we built the back wall so that the window is inside (vs outside) the theater am confident that I could solve the issue of sound going through the window via plugs.

The bigger issue, however, is that we ideally want the window to be OUTSIDE of the Theater. That's because it's one of 2 large windows on either side of our doorwall that let light into the basement. That, and we have a nice view out of it.

We really, really do not want to put the window inside the Theater. But that limits how "long" the theater can be (to around 17'). And if I then do an AT wall again, I can only do one row of seats - that is, unless I can figure out something like the angled wall. The whole motivation for the angled wall is to keep the window outside the HT (for view and light, not because of sound leakage)..

The $64M question then becomes..what happens to acoustics if we do have a roughly 7-8', 45 degree angle wall for our left rear corner with the rest of the wall normal left-to-right straight..

We're also considering doing the room without a back wall and leaving the HT open to the rest of the basement. I'd "think" acoustics would become really simple at that point as we wouldn't have any bouncing of sound waves off the rear wall. Is that right? Or would we still have acoustic challenges even without a back wall?


----------



## nathan_h

BBB_63 said:


> We're also considering doing the room without a back wall and leaving the HT open to the rest of the basement. I'd "think" acoustics would become really simple at that point as we wouldn't have any bouncing of sound waves off the rear wall. Is that right? Or would we still have acoustic challenges even without a back wall?


This helps with reflections off the back wall (ie, fewer of them!). 

But it makes bass management a challenge, and you'll need significantly larger subwoofers, and of course light control then becomes an issue. 

And rear speakers become challenging.

But it's probably better than an angled wall.

--

If you absolutely need two rows, then you need two rows, and you can go with the angled wall. I think it will look weird outside the theater room and there might be some building code about how much clearance you need around a window, meaning you'll need to eat up more of the theater space.

But if you don't need two rows (and most AVSers learn that their theater needs that second row a couple times a year, it seems, at most) then a one row theater is more elegant, easier to manage, easier to fill with sound, easier to optimize for the main seats, etc. (Pay attention to screen size and throw distance in a one row theater. You might want to place the projector in a shelf OUTSIDE the theater, projecting into the theater, to get the right throw distance. This also has the benefit of keeping the noise and the heat from the projector outside the theater.)


----------



## BBB_63

Thanks..the reason for 2 rows is that wife liked sitting in our front row (about 12') and I liked sitting in back row (about 18', on a 1' riser) in our last HT (which was 23' long overall). That, and to a lesser degree, being able to have more than 4 seats which is all we can fit with a 14' room width. (We had 5 in our last HT - 3 Berkline 088s in the back and 2 Berkline 45003s in the front. Worked great).

I still have an old PJ laying around and just put up a 110'' image on the wall downstairs and tried sitting 12' back and at 'ground' level. Hated it, just like I remembered not loving sitting in the front row of our old HT. I just really prefer sitting further back and up on a riser. Gives me much more of a "theater" feeling than sitting 12' away from the image on the floor..


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## fattire

BBB_63 said:


> the reason for 2 rows is that wife liked sitting in our front row (about 12') and I liked sitting in back row (about 18', on a 1' riser) in our last HT (which was 23' long overall).


Different field of view preferences are tough to solve for sure.



BBB_63 said:


> We're also considering doing the room without a back wall and leaving the HT open to the rest of the basement. I'd "think" acoustics would become really simple at that point as we wouldn't have any bouncing of sound waves off the rear wall. Is that right? Or would we still have acoustic challenges even without a back wall?


If no back wall doesn't create a light issue for you, then it's a good option. You would still have sound bouncing off the back wall, but the increased distance means increased attenuation. Without the wall, that room looks _really_ deep. You'll loose 6 dB for every doubling of distance, plus the back walls aren't perfectly reflective. I bet any issues from those reflections would be easy to address with a bit of absorption; perhaps some DIY art-panel absorbers to help them blend in. Heck, at the distance I'm perceiving in the picture, you might even be able to use diffusion. Probably more of a decor call than anything else at that point.


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## 3fingerbrown

Hey guys I'm trying to acoustically treat a home sport court/gymnasium. Because it is such a big and hard room, I need a lot of treatments to have any effect (about 576 square feet, or eighteen 4x8 panels!) so the price gets out of control quickly when looking at pre-made panels. And the amount of labor required to build that many panels myself with the traditional wood frames is also pretty significant.

Aesthetically, I'm willing to make a lot of compromises since these panels will go on a ceiling that is 20 feet in the air. They really won't be visible. The ceiling is white and with white panels, I think they will blend into the ceiling, hiding any imperfections. In other words, this is a very different application than the nice theaters featured on this forum.

My budget plan is to buy a bunch of OC 703 panels and use this edge hardener stuff:









NO-FRAME Fiberglass Edge Coating for Frameless Acoustical Panels


Learn how to use NO-FRAME fiberglass edge coating for frameless acoustical panels. Our fiberglass edge coating is designed for sound-proofing projects.




www.buyinsulationproductstore.com





Then I will wrap the panels with some fairly inexpensive white cotton fabric.

Here is a video from someone that did this exact thing:






My questions:

Is this a good idea for cheap acoustic panels? Is there a better idea?
What size panels? Should I do 2x4, 4x4, or 4x8 size panels? Bigger panels cover more area, but are 4x8 panels too big to work with? Wrapping with fabric and hanging a 4x8 panel could be tricky.
Should I use spray glue to hold the fabric to the back of the OC703?
What about using OC705 panels that are stiffer, but without any edge hardener?
What is the best method to affix the panels to a ceiling?

Thanks!!!


----------



## nathan_h

What is your goal? What is your budget? What prices are you getting on the panels?

I suspect these data points will help with getting you better answers.


----------



## 3fingerbrown

nathan_h said:


> What is your goal? What is your budget? What prices are you getting on the panels?
> 
> I suspect these data points will help with getting you better answers.


Well If I buy a ready made 4'x8' panel with a 2 inch thickness, I'm looking at a quote of $270 per 4x8 panel. This is for a polyester panel from Acoustical Solutions. For 18 of these panels, I'm looking at over $4800 and over $5k by the time you add shipping in.

If I buy OC703 panels and wrap them myself in fabric, I think I could get the cost down to about $100 per panel, or $1,800 total. It is $64 for each 4x8 of Oc703, plus about $45 in fabric if I go with something inexpensive at $15 a yard.

So it is a pretty big savings if I go the DIY route. And the labor involved doesn't seem too difficult. I haven't wrapped a 4x8 panel in fabric, that won't be easy but should be doable. On the youtube video they used spray glue to affix the fabric to the panel, would that work? And should I go with larger 4x8 panels for speed and scale or 2x4 panels for ease of working with smaller panels?


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## nathan_h

If you are one person, I would go with 2'x4' panels. They get heavy and awkward if any larger. Hekc even 2x4' panels are heavy and awkward on a ladder, overhead.

I suspect you will need the rigidity of a real frame, especially if you want to hang them a few inches off the ceiling (which is a useful because it increases the effective frequencies they work at).

These kits put a 2x4 foot panel at $50 each: Acoustimac DIY422 Acoustic Panel Kit which might be something to consider. You may need additional hardware to hang them as you intend, but this is nice looking fabric, good insulation and a solid frame.

---


But I am not sure what you are trying to achieve. Or how it has to look. You could staple batts of insulation to the ceiling, in a loose looping pattern, covered in jute or similar cheap woven material, and save a lot of money, and achieve good results, too.


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## bwhitmore

Does anyone sell acoustic panels (adhesive backed?…1-2” thick?) that could attach to a wood panel and come anywhere close to the acoustic properties of the traditional DIY panels we all build here (OC703 in fabric wrapped wood frame)…?

I have a theater build that’s giving me fits…going the traditional 703/fabric/frame route seems tricky. Trying to get “close” for this unique situation.

Thanks!


----------



## nathan_h

If it’s light enough for adhesive to hold it up then it is usually less effective at absorbing sound but these kinds of panels work sort of like you want. You’d need to add your own adhesive. And removing them later would damage the panels and the wall, of course!

It’s half as effective or twice as expensive as fiberglass but way better than nothing. 









AcoustiColor® Acoustic Shapes


Orders of $2,500 or more may require longer lead times. Please contact us if there are any questions. Customizable




www.audimute.com


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## nathan_h

Hiccup


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## bwhitmore

nathan_h said:


> If it’s light enough for adhesive to hold it up then it is usually less effective at absorbing sound but these kinds of panels work sort of like you want. You’d need to add your own adhesive. And removing them later would damage the panels and the wall, of course!
> 
> It’s half as effective or twice as expensive as fiberglass but way better than nothing.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> AcoustiColor® Acoustic Shapes
> 
> 
> Orders of $2,500 or more may require longer lead times. Please contact us if there are any questions. Customizable
> 
> 
> 
> 
> www.audimute.com


this is great…thanks very much

I’d be attaching them to wood panels in the room, that are hung on the wall…so not worried about damage to the drywall

the room sounds really great to my ear as is…I had planned on a bunch of DIY panels but now I think I can get by with a few aesthetically pleasing panels that at least have SOME functionality


----------



## 314carpenter

Finally received those decorative lattice panels from Home Depot. Very impressed with the quality. Much thicker and heavier than I expected them to be. I already like how matte they are. Let's see how they perform for this application.

The idea here is to add diffusion/scattering properties to existing 2'X4'X2" acoustic panels, inside of an otherwise well treated room, which may tend to sound a bit over damped.

Anyone here know REW enough to know what I should be measuring for, what graphs to look at, what checks to click on?

I have some suggestions, I would appreciate your feedback:
1)Turn off Audyssey
2)Measure one speaker
3)UMIK-1 placed 1 Meter away on axis
4)Take a baseline measurement without panels
5)Second measurement after placing two standard acoustic panels adjacent to the speaker, at exactly 45 degrees angled out from the speaker, following the same procedures above. 
6)Third measurement with the new scatter plates installed onto the acoustic panels, same procedure.









Barrette Outdoor Living 2 ft. x 4 ft. Sprig Black Polypropylene Decorative Screen Panel 73004791 - The Home Depot


With a variety of rich and elegant designs, Barrette Outdoor Living Decorative Screen Panels can enhance either an indoor or an outdoor space. Thicker than standard lattice panels, the 2 ft. x 4 ft. screens



www.homedepot.com


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## Snoochers

Hi all. I'm finally getting around to placing acoustic treatments in my 21x16x9' dedicated home theatre. I will handle absorption easily enough but diffusers are more complicated. I want to make/source them myself and I don't know where to start. FYI I am limited to 4" and 6" thickness for diffusers. Questions:


What are some easy/economical DIY 3D and 2D diffuser designs? I see the "skyline" type frequently which seems achievable but is also a decent amount of work. I imagine there is some kind of pre-existing material out there that I can just throw on a wall and hide with fabric? A dense salad bowl? Lol.
How can I make diffusers lightweight? A solid wood skyline diffuser would be too heavy for me to hang on the ceiling. I'm using three layers of drywall on clips and channels. Everything should be good to go but I'd like to avoid excessive weight up there to be safe.
FYI I'm having a look through the thread but with almost 700 pages I reckon I won't be able to get it all.


----------



## Snoochers

carp said:


> Nice Frolich!
> 
> I did something similar recently. I did kind a combo between what's on that video and this room: Home Theater of the Month: The Event Horizon
> also taking a lot of advice from @harrisu .
> 
> First reflection points on both side walls, same with first reflection point on the ceiling:
> View attachment 3235184
> 
> 
> I covered all the checkerboard diffusion/absorption panels with AT velvet from hobby lobby. You can see in this pic I have a few diffusion panels directly above my front row, I plan on adding more.
> View attachment 3235187
> 
> 
> Since these pictures were taken I have swapped out the 2 2'x2' absorption panels on the rear wall with the diffusion panels that are in front of the side surrounds, and I like it better that way.
> View attachment 3235190
> 
> Frolich - I see you didn't take the advice in the video that talked about not having matched treatments, for example if you have a diffusion panel on the left wall then there should be absorption directly across from it.
> 
> I just couldn't do that either... my MLP seat is dead center and it would drive me nuts not to have the treatments the same on each side of me. I suppose I'll try it but I'm really liking the results as is. I do think I'll get more of the skyline diffusor treatments for the rear part of the room on the ceiling and maybe some more absorption for that area of the ceiling too, but I'm going to live with this for awhile since I'm liking it.
> View attachment 3235194
> 
> View attachment 3235196
> 
> View attachment 3235197
> 
> View attachment 3235199


What are all the semi-rounded diffusers here? DIY or purchased product?


----------



## squared80

Snoochers said:


> I want to make/source them myself and I don't know where to start.


I did a ton of research on here and online. Just be careful who you listen to in places like YouTube. Lot of amateurs not doing them properly.

*That said, you can build some decent ones on a budget.* I'd highly recommend downloading QRDude first. Fast and simple.






QRDude: Quadratic Residue Diffuser calculator


Free calculator for designing standard and advanced QRD diffusers



www.subwoofer-builder.com





Skyline Diffuser
Buy a bunch of 2x2 and cut them into the lengths for however large or small you want them, per QR Dude.








2 in. x 2 in. x 8 ft. Furring Strip Board Lumber 75800593 - The Home Depot


Every piece of 2 in. x 2 in. x 8 ft. Furring Strip Board is perfect for a wide range of uses including carpentry, hobbies, shelving and general finish work. Create a level surface for attaching wallboard



www.homedepot.com





Quadratic Diffuser
LOTS of ways to do this. Use the QRDude to see well depth and width, but you can buy 1" foamboard and build it that way, or use hardboard (I'm doing the latter).








R-Tech 1 in. x 4 ft. x 8 ft. R-3.85 Insulating Sheathing 320821 - The Home Depot


R-Tech 1 in. x 4 ft. x 8 ft. Insulation Sheathing cuts easily to size. Facilitating its installation as wall sheathing, basement and foundation insulation or siding underlayment. This product meets federal



www.homedepot.com












Hardboard Tempered Panel (Common: 1/8 in. 4 ft. x 8 ft.; Actual: 0.115 in. x 47.7 in. x 95.7 in.) 832777 - The Home Depot


This is a premium hardboard with high internal bond, exceptional stability and smoothness that's ideal for paneling, furniture, fixtures, toys, general manufacturing and applications where painting or



www.homedepot.com


----------



## Snoochers

squared80 said:


> I did a ton of research on here and online. Just be careful who you listen to in places like YouTube. Lot of amateurs not doing them properly.
> 
> *That said, you can build some decent ones on a budget.* I'd highly recommend downloading QRDude first. Fast and simple.
> 
> 
> 
> 
> 
> 
> QRDude: Quadratic Residue Diffuser calculator
> 
> 
> Free calculator for designing standard and advanced QRD diffusers
> 
> 
> 
> www.subwoofer-builder.com
> 
> 
> 
> 
> 
> Skyline Diffuser
> Buy a bunch of 2x2 and cut them into the lengths for however large or small you want them, per QR Dude.
> 
> 
> 
> 
> 
> 
> 
> 
> 2 in. x 2 in. x 8 ft. Furring Strip Board Lumber 75800593 - The Home Depot
> 
> 
> Every piece of 2 in. x 2 in. x 8 ft. Furring Strip Board is perfect for a wide range of uses including carpentry, hobbies, shelving and general finish work. Create a level surface for attaching wallboard
> 
> 
> 
> www.homedepot.com
> 
> 
> 
> 
> 
> Quadratic Diffuser
> LOTS of ways to do this. Use the QRDude to see well depth and width, but you can buy 1" foamboard and build it that way, or use hardboard (I'm doing the latter).
> 
> 
> 
> 
> 
> 
> 
> 
> R-Tech 1 in. x 4 ft. x 8 ft. R-3.85 Insulating Sheathing 320821 - The Home Depot
> 
> 
> R-Tech 1 in. x 4 ft. x 8 ft. Insulation Sheathing cuts easily to size. Facilitating its installation as wall sheathing, basement and foundation insulation or siding underlayment. This product meets federal
> 
> 
> 
> www.homedepot.com
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hardboard Tempered Panel (Common: 1/8 in. 4 ft. x 8 ft.; Actual: 0.115 in. x 47.7 in. x 95.7 in.) 832777 - The Home Depot
> 
> 
> This is a premium hardboard with high internal bond, exceptional stability and smoothness that's ideal for paneling, furniture, fixtures, toys, general manufacturing and applications where painting or
> 
> 
> 
> www.homedepot.com


Thanks. This seems reasonable to do. Could I do a skyline with hard insulating sheathing? I'm surprised it is considered dense enough to act as a diffuser? I'd love to hear your thoughts on it.


----------



## fattire

Snoochers said:


> Thanks. This seems reasonable to do. Could I do a skyline with hard insulating sheathing? I'm surprised it is considered dense enough to act as a diffuser? I'd love to hear your thoughts on it.


A lot of the quadratic-style diffusers sold online are polystyrene. Anthony Grimmani even specs and sells them from his Sonitus USA business. Diffusion is about higher frequencies and they don't go through things like the lower frequencies do. The one I just linked is show effect from 600 Hz - 4 kHz.

EDIT: He sells wood and polystyrene versions of the same diffusers.


----------



## squared80

Snoochers said:


> Thanks. This seems reasonable to do. Could I do a skyline with hard insulating sheathing? I'm surprised it is considered dense enough to act as a diffuser? I'd love to hear your thoughts on it.


Anything with a harder surface is fine, including XPS, wood, plastic, etc., etc. Doesn't matter what it is for the higher frequencies. I thought balsa wood would be an option but it's amazingly expensive.


----------



## Snoochers

fattire said:


> A lot of the quadratic-style diffusers sold online are polystyrene. Anthony Grimmani even specs and sells them from his Sonitus USA business. Diffusion is about higher frequencies and they don't go through things like the lower frequencies do. The one I just linked is show effect from 600 Hz - 4 kHz.
> 
> EDIT: He sells wood and polystyrene versions of the same diffusers.


Thanks for the info! I see these aren't quite as broad spectrum as lets say thick absorption. I think with 4" depth I'm limited to a range around 500-5000hz or so. Should I try to throw in a few really deep ones elsewhere to hit some lower parts of the spectrum? I have a 18" radius hemicylinder already but nothing quadratic or the like.


----------



## Snoochers

squared80 said:


> Anything with a harder surface is fine, including XPS, wood, plastic, etc., etc. Doesn't matter what it is for the higher frequencies. I thought balsa wood would be an option but it's amazingly expensive.


So to make a skyline diffuser I can just buy some owens corning dense insulation 2" thick, run it through the table saw to make 2" pieces and go nuts chopping it into the correct lengths?


----------



## fattire

Snoochers said:


> Thanks for the info! I see these aren't quite as broad spectrum as lets say thick absorption. I think with 4" depth I'm limited to a range around 500-5000hz or so. Should I try to throw in a few really deep ones elsewhere to hit some lower parts of the spectrum? I have a 18" radius hemicylinder already but nothing quadratic or the like.


It's really the room that decides what kind of diffusion & absorption we need. I'm going from memory here so please excuse any inaccuracies ...

We're shooting for an RT60 between 300 - 600 ms. Small rooms don't really have an RT60, but I have found the T30 measurement in REW to be a good proxy. The other thing we want is for the reverb time to be consistent. Using the 1/3 octave view (bars are easier than the lines to see this), we don't want more than a 25% difference between one bar (a given 1/3 octave) and the next (the neighbor 1/3 octaves).

Using the T30 plot, you'll be able to see what problematic frequencies you might need to address. Don't forget that diffusion makes any existing absorption more effective by reducing the energy of the reflections. You could add diffusion and then find you're over absorbed.


----------



## squared80

Snoochers said:


> So to make a skyline diffuser I can just buy some owens corning dense insulation 2" thick, run it through the table saw to make 2" pieces and go nuts chopping it into the correct lengths?


It will make an absolute mess, but yes.


----------



## nathan_h

fattire said:


> It's really the room that decides what kind of diffusion & absorption we need. I'm going from memory here so please excuse any inaccuracies ...
> 
> We're shooting for an RT60 between 300 - 600 ms. Small rooms don't really have an RT60, but I have found the T30 measurement in REW to be a good proxy. The other thing we want is for the reverb time to be consistent. Using the 1/3 octave view (bars are easier than the lines to see this), we don't want more than a 25% difference between one bar (a given 1/3 octave) and the next (the neighbor 1/3 octaves).
> 
> Using the T30 plot, you'll be able to see what problematic frequencies you might need to address. Don't forget that diffusion makes any existing absorption more effective by reducing the energy of the reflections. You could add diffusion and then find you're over absorbed.


I think that following your steps here will get one a very good result.

---

For pedantic completeness, I'll quote some instructions you shared with me a while back for viewing RT60 in REW:



> Here's the process:
> 
> Open up an mdat with full range measurements of your L+R
> Select a measurement on the left, then go to "RT60 Decay" window
> The graphs will (probably) be empty
> Hit the "Generate" button in the bottom left of the bottom graph
> Hit the "Controls" gear
> Hit "Calculate RT60 Model"
> Now, go to the regular RT60 window. The measurement you used above will now have an RT60 . This is also supported in the "Overlays" graphs making it super easy to compare before/after.


----

And I'll share the Dolby specification for what they want to see in a mastering suite:


----------



## fattire

nathan_h said:


> I think that following your steps here will get one a very good result.
> 
> ---
> 
> For pedantic completeness, I'll quote some instructions you shared with me a while back for viewing RT60 in REW:
> 
> 
> 
> ----
> 
> And I'll share the Dolby specification for what they want to see in a mastering suite:
> 
> View attachment 3293993


Nice! I hadn’t seen those from Dolby before. It’s my understanding that the recommended home range of 300-600ms is to allow for some “preference” to be layered on top of the “reference”. I’ve personally landed on about the middle range. Too low and the soundstage is too narrow for my liking. Too high and the room sounds a bit chaotic.


----------



## Snoochers

fattire said:


> It's really the room that decides what kind of diffusion & absorption we need. I'm going from memory here so please excuse any inaccuracies ...
> 
> We're shooting for an RT60 between 300 - 600 ms. Small rooms don't really have an RT60, but I have found the T30 measurement in REW to be a good proxy. The other thing we want is for the reverb time to be consistent. Using the 1/3 octave view (bars are easier than the lines to see this), we don't want more than a 25% difference between one bar (a given 1/3 octave) and the next (the neighbor 1/3 octaves).
> 
> Using the T30 plot, you'll be able to see what problematic frequencies you might need to address. Don't forget that diffusion makes any existing absorption more effective by reducing the energy of the reflections. You could add diffusion and then find you're over absorbed.


well my issue is that I have too much absorption so I’m going to add diffusion and then remove absorption. I think it’s less a question of RT60 for me and more about treating the surfaces for acoustic preference.


----------



## fattire

Snoochers said:


> well my issue is that I have too much absorption so I’m going to add diffusion and then remove absorption. I think it’s less a question of RT60 for me and more about treating the surfaces for acoustic preference.


RT time and "too much absorption" are the same thing. The former is used to quantify the latter.

If you area able to take measurements, they'll give a benchmark of sorts on your preferences and what you consider "too much absorption". Then you can gauge the effectiveness of changes as you make them to really dial things in to your liking.


----------



## nathan_h

fattire said:


> Nice! I hadn’t seen those from Dolby before. It’s my understanding that the recommended home range of 300-600ms is to allow for some “preference” to be layered on top of the “reference”. I’ve personally landed on about the middle range. Too low and the soundstage is too narrow for my liking. Too high and the room sounds a bit chaotic.


I'm finding that within the accepted range of RT60 values, room size is a factor. That is, in my bedroomsized temporary theater, I ended up needing a shorter decay time than in my old garage-sized theater.....say .2 or even a touch below, in the tiny room, and more like .3 in the larger room.


----------



## mikela

Snoochers said:


> What are all the semi-rounded diffusers here? DIY or purchased product?


Auralex Geofusor


----------



## fattire

nathan_h said:


> I'm finding that within the accepted range of RT60 values, room size is a factor. That is, in my bedroomsized temporary theater, I ended up needing a shorter decay time than in my old garage-sized theater.....say .2 or even a touch below, in the tiny room, and more like .3 in the larger room.


It should also be easier to get smaller RT in a smaller room - There's less distance between boundaries so sound takes less time to hit "something" that will diffuse/absorb it (assuming a room with the "stuff of life" in it and not a bare walled room). That's fundamentally why acoustically small rooms don't have a real RT60 in the first place.


----------



## nathan_h

mikela said:


> Auralex Geofusor


Those are good, in the "22" version. The "11" strikes me as too shallow. It's a shame the fire rated ones are almost double the price.

Personally I like their Hemisphere model best.


----------



## mikela

nathan_h said:


> Those are good, in the "22" version. *The "11" strikes me as too shallow.* It's a shame the fire rated ones are almost double the price.
> 
> Personally I like their Hemisphere model best.


The 11.75" has a 4.25" depth while the 23.75" has a 4.5" depth. The checker board pattern of 1' (4" depth) absorbers and 1' diffusors is used to create a seamless sound field for the surround speakers in my system.


----------



## nathan_h

Good good to know. I was under the impression the 11 model was shallower.

Thats half the battle with diffusion: A shallow depth defeats the efficacy of many designs, which would ideally get down to the room transition frequency.

The other half the battle is that unlike absorption, there is a required distance between ears and diffuser in order to have the results work correctly.


----------



## Heath7

Snoochers said:


> What are some easy/economical DIY 3D and 2D diffuser designs? I see the "skyline" type frequently which seems achievable but is also a decent amount of work. I imagine there is some kind of pre-existing material out there that I can just throw on a wall and hide with fabric? A dense salad bowl? Lol.


Mine are easy, though maybe not the most economical. Plus side is "The Force" increases sound quality by 50%. 😆


----------



## mikela

nathan_h said:


> The other half the battle is that unlike absorption, there is a required distance between ears and diffuser in order to have the results work correctly.


True and it should be noted that gentle geometric diffusors like the Geofusor can operate much closer to the ear than a more complex diffusor like the citiscape types.


----------



## Snoochers

fattire said:


> RT time and "too much absorption" are the same thing. The former is used to quantify the latter.
> 
> If you area able to take measurements, they'll give a benchmark of sorts on your preferences and what you consider "too much absorption". Then you can gauge the effectiveness of changes as you make them to really dial things in to your liking.


I certainly have too much absorption because my RT60 is already between 200-300 for the most part and I haven't treated the ceiling or two of the walls and have 0 diffusion! So I need to add all that stuff and selectively remove. I loaded my front wall with insulation like a lot of folks do but it will lead to deadening if I left it as is.


----------



## carp

Snoochers said:


> I certainly have too much absorption because my RT60 is already between 200-300 for the most part and I haven't treated the ceiling or two of the walls and have 0 diffusion! So I need to add all that stuff and selectively remove. I loaded my front wall with insulation like a lot of folks do but it will lead to deadening if I left it as is.


I don't know about the recommendations on RT60... at least for my own ears that is. 

My room is currently at 150 which supposedly means it's very dead. It sure doesn't seem that way to me, I've been in plenty of HT's that were too dead and it made it uncomfortable to be in them for very long. I don't get that same effect in my room and both music and movies sound great. 

Like you my front wall is all insulation, and I've tried it without it and I prefer the insulation in for sure. I don't have a ton of absorption in the rest of the room, I have 20 square feet on each side wall, 8 square feet on the rear wall, and 8 square feet on the ceiling (all 6 inches thick). That isn't much in a 23' long 17' wide room. 

For diffusion I have 16 square feet on each side wall, 14 square feet on the ceiling, and 16 square feet on the back wall.

I admit it bugs me to look at the RT60 results... it would feel nice to have the numbers say I'm where I'm supposed to be but I don't think it's possible for the graph to say that and have me liking the sound at the same time. I'm sure there is a decent chance I'm doing something wrong with my measurements.


----------



## Snoochers

carp said:


> I don't know about the recommendations on RT60... at least for my own ears that is.
> 
> My room is currently at 150 which supposedly means it's very dead. It sure doesn't seem that way to me, I've been in plenty of HT's that were too dead and it made it uncomfortable to be in them for very long. I don't get that same effect in my room and both music and movies sound great.
> 
> Like you my front wall is all insulation, and I've tried it without it and I prefer the insulation in for sure. I don't have a ton of absorption in the rest of the room, I have 20 square feet on each side wall, 8 square feet on the rear wall, and 8 square feet on the ceiling (all 6 inches thick). That isn't much in a 23' long 17' wide room.
> 
> For diffusion I have 16 square feet on each side wall, 14 square feet on the ceiling, and 16 square feet on the back wall.
> 
> I admit it bugs me to look at the RT60 results... it would feel nice to have the numbers say I'm where I'm supposed to be but I don't think it's possible for the graph to say that and have me liking the sound at the same time. I'm sure there is a decent chance I'm doing something wrong with my measurements.


This was interesting, thank you! I will keep most of the insulation upfront but I’m going to play around and see where things land


----------



## Snoochers

I got a couple cardboard forms for concrete (sonostube style) that I cut in half to act as diffusing hemicylinders. They’re 1/2” dense cardboard or so, which I imagine let’s a fair bit of noise pass through them directly. Should I try to line them with mass to make them more acoustically opaque or are they likely doing the job as diffusers already?


----------



## nathan_h

I'd guess those are plenty thick.


----------



## Snoochers

nathan_h said:


> I'd guess those are plenty thick.


Oh yeah? I'm just thinking if I was standing in that tube I would hear a hell of a lot which tells me obviously sound is getting through, which means that sound isn't being diffused?


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## nathan_h

I suspect it’s mostly bass you would hear, and that’s not going to get diffused anyway


----------



## BBB_63

What are you guys doing for back wall OC703 thickness nowadays? 

We built our first HT in 2007-2008 and had 2'' OC703 w/FSK, and the room sounded awesome. But it seems like the norm nowadays is more 6''?

Can anyone explain the benefits of the thicker material? Based on our previous experience, 2'' with FSK was awesome (to our untrained ears).

If we use Fabricmate tracks on the wall, how in the heck do you do 6'' of treatment materials? I may have missed it, but the max track depth I saw on their site was 4''.

TIA..


----------



## nathan_h

6" of depth gives you broadband absorption quite a bit lower than 2".

2" helps you down to about 400 hz before they roll off.

6" down to about 150 hz before they roll off, effectively treating down close to where your bass management and multiple subwoofers tend to start working.

All things being equal, the latter is a good bet for the best results. 

But in the end, measuring the room is very helpful, and seeing the decay times at various frequencies is a great way to assess success objectively.

This is NOT to say that if you can only do 2" or 4" panels that those are worthless or bad. They can still make a huge improvement over an untreated room. In fact, I'd venture to guess that most people building DIY panels, myself included, often make them 4" (or 3.5") deep because in many rooms it is hard to accommodate anything thicker.

I cannot answer the fabricmate question. I've been mostly looking at designs where there is a wood frame for the fabric wall, and that frame can be made any depth.


----------



## BBB_63

nathan_h said:


> 6" of depth gives you broadband absorption quite a bit lower than 2".
> 
> 2" helps you down to about 400 hz before they roll off.
> 
> 6" down to about 150 hz before they roll off, effectively treating down close to where your bass management and multiple subwoofers tend to start working.
> 
> All things being equal, the latter is a good bet for the best results.
> 
> But in the end, measuring the room is very helpful, and seeing the decay times at various frequencies is a great way to assess success objectively.
> 
> This is NOT to say that if you can only do 2" or 4" panels that those are worthless or bad. They can still make a huge improvement over an untreated room. In fact, I'd venture to guess that most people building DIY panels, myself included, often make them 4" (or 3.5") deep because in many rooms it is hard to accommodate anything thicker.
> 
> I cannot answer the fabricmate question. I've been mostly looking at designs where there is a wood frame for the fabric wall, and that frame can be made any depth.


Thanks! Makes sense..


----------



## BBB_63

Would a fabric with a NRC rating of .90 (vs GOM's FR701 of .95) be OK to use for wall fabric?

We found a newer GOM fabric (Synopsis) that we prefer style-wise to 701 and may want to use that instead. Here's the absorption chart, followed by FR701s (from the Guilford of Maine website)..I do see a minor drop-off after 250 Hz compared to the FR701, but assume this is probably no big deal?










FR701:


----------



## nathan_h

Maybe I haven't had enough coffee today but those charts are confusing me.

But to generalize, a small variation isn't likely to make a significant difference when using them for absorption panels. 

The most extreme cases I have seen were comparing things like the DMD and the Suede fabric from Acoustimac -- and in fact they say that if you are using their Seude fabric you should use more panels in the room because it doesn't allow as much sound through.... 

---

Presumably all this makes more difference when covering speakers with these 'acoustic fabrics' so (for example) using the Acoustimac suede in front of speakers is probably a bad idea (versus their DMD or Executive fabric).

---

But I don't see anything that would push you away from using the GOM fabric you want to use. 

(Note that there is at least one GOM fabric that is surprisingly un neutral. The measurements have been posted in this thread at some time. I don't think it's the one you are talking about but I cannot find the graphic right now. And even if it is the same one, for panels I don't think I would worry. In front of speakers, I would.)


----------



## Snoochers

BBB_63 said:


> Would a fabric with a NRC rating of .90 (vs GOM's FR701 of .95) be OK to use for wall fabric?
> 
> We found a newer GOM fabric (Synopsis) that we prefer style-wise to 701 and may want to use that instead. Here's the absorption chart, followed by FR701s (from the Guilford of Maine website)..I do see a minor drop-off after 250 Hz compared to the FR701, but assume this is probably no big deal?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> FR701:


I'd be careful putting much GOM fabric. It is not sufficiently transparent and ends up blocking a lot more on the high end than expected.


----------



## Snoochers

I need to put up some diffusers and I have 4" of depth available to me. A typical skyline diffuser that is 4" deep scatters and diffuses from about 500hz to 3500hz according to QRDude. A 2" depth does the same for about 1000hz to 7000hz. Should I be building all 4" diffusers or should I be making 2", 3" and 4" diffusers to catch different frequencies? With absorption I know I need to max out depth but with diffusion I don't know.


----------



## nathan_h

What I see pros like Nyal and Grimani do is use hemispherical or semi tubular diffusion which apparently works much better in domestic sized rooms than the skyline style.


----------



## BBB_63

Snoochers said:


> I'd be careful putting much GOM fabric. It is not sufficiently transparent and ends up blocking a lot more on the high end than expected.


Not clear on why that would be? AFAIK, GOM (especially FR701) has pretty much been "the" standard fabric used in HT design for decades now.

Most GOM fabrics also have a NRC rating (measured through lab tests performed to exacting scientific standards) of either 95 or 90 percent. How is that not acoustically transparent?

What other fabrics are people using nowadays?


----------



## Snoochers

BBB_63 said:


> Not clear on why that would be? AFAIK, GOM (especially FR701) has pretty much been "the" standard fabric used in HT design for decades now.
> 
> Most GOM fabrics also have a NRC rating (measured through lab tests performed to exacting scientific standards) of either 95 or 90 percent. How is that not acoustically transparent?
> 
> What other fabrics are people using nowadays?


I don’t have everything in front of me but Floyd Toile’s book covers it in detail. These fabrics are not that transparent and if you hold it up to your mouth and breath in it that’s quite clear. Sound that comes in on an angle gets affected considerably by fabric in front of absorbers if it isn’t very transparent.


----------



## Snoochers

nathan_h said:


> What I see pros like Nyal and Grimani do is use hemispherical or semi tubular diffusion which apparently works much better in domestic sized rooms than the skyline style.


I have two huge hemycilonders already but I need some more coverage !


----------



## BBB_63

Snoochers said:


> I don’t have everything in front of me but Floyd Toile’s book covers it in detail. These fabrics are not that transparent and if you hold it up to your mouth and breath in it that’s quite clear. Sound that comes in on an angle gets affected considerably by fabric in front of absorbers if it isn’t very transparent.


Thanks, but I'm still confused. People have used materials from Guilford of Maine for literally decades now in HT design with AT fabric walls. There are also standards-based scientific tests that measure transparency, and the net is that it's 90 - 95% transparent depending on the fabric chosen, per those scientific lab tests. 

Why would GOM be the defacto standard for HT design if it's supposedly NOT transparent? I've read literally hundreds (if not more) of posts over the past 15-20 years saying it IS very transparent, and the scientific lab tests seem to back that up.

ETA - we did not use GOM in our last HT, but we did use fabric a designer picked out that was "supposedly" transparent..no ratings..no scientific tests..just "supposedly" transparent..and it worked great!


----------



## Snoochers

BBB_63 said:


> Thanks, but I'm still confused. People have used materials from Guilford of Maine for literally decades now in HT design with AT fabric walls. There are also standards-based scientific tests that measure transparency, and the net is that it's 90 - 95% transparent depending on the fabric chosen, per those scientific lab tests.
> 
> Why would GOM be the defacto standard for HT design if it's supposedly NOT transparent? I've read literally hundreds (if not more) of posts over the past 15-20 years saying it IS very transparent, and the scientific lab tests seem to back that up.
> 
> ETA - we did not use GOM in our last HT, but we did use fabric a designer picked out that was "supposedly" transparent..no ratings..no scientific tests..just "supposedly" transparent..and it worked great!


Haha Funny you say that I was just as surprised as you were. I was going to buy hundreds of feet of GOM until I saw the data. Also I don’t think the NRC value necessarily reflects transparency though I’m a bit rusty on that. On top of all that is 95% transparent enough? I’ve trying to attach a excerpt from the book but I’m having trouble.


----------



## BBB_63

Snoochers said:


> Haha Funny you say that I was just as surprised as you were. I was going to buy hundreds of feet of GOM until I saw the data. Also I don’t think the NRC value necessarily reflects transparency though I’m a bit rusty on that. On top of all that is 95% transparent enough? I’ve trying to attach a excerpt from the book but I’m having trouble.


It sounds like you're taking the word of one book author over the direct experience of dozens if not hundreds of AVS Forum members who have all successfully used FR701 and other GOM fabrics in their theaters for decades now..

Just sayin that you might want to consider that this one book author may not know what he/she is talking about, regardless of how credible they may sound.


----------



## Snoochers

BBB_63 said:


> It sounds like you're taking the word of one book author over the direct experience of dozens if not hundreds of AVS Forum members who have all successfully used FR701 and other GOM fabrics in their theaters for decades now..
> 
> Just sayin that you might want to consider that this one book author may not know what he/she is talking about, regardless of how credible they may sound.


Well first off we're talking about Floyd Toole here. If you're not aware of who he is then that is fine obviously but there is no greater authority in the world on this kind of stuff. Second, this is not his opinion, this is hard data from objective measurements. See photo.


----------



## nathan_h

The data Toole shares is not wrong. The conclusion that this means fabric is inherently bad is wrong. What it means is you can get close and estimate how many and what kinds of panels and fabric are useful. Then you put them up and you measure the results. In particular you measure the decay times.....not a single RT60 for the room, but an RT60 for each octave of human hearing, and you see whether you have achieved your goal. If you have, great. If not, adjust things. 


Honestly in the Toole graphic I would prefer the "fabric" line because it is more consistent across the audible spectrum than the plain fiberglass line, which looks likely to kill the top two octaves 5k to 20k more thoroughly that I would want. I actually want very similar impact across the whole audio spectrum, which this graphic shows is easier with fabric on the panels......


----------



## fattire

Additionally, at 10kHz the wavelengths are _tiny_; ~0.113 inches, and they only get smaller going up. You only need to absorb absorb 1/4 - 1/2 of a wavelength (0.02825 - 0.0565 inches) to start to see absorption. I'm eyeballing some GOM FR701 right now and it's at least that thick. Any fabric used will likely have a very similar impact. Any fabric that doesn't have that impact will likely be both acoustically and visually transparent/sheer defeating the purpose for which it's being used. Unfortunately you can't have your cake and eat it too.


----------



## Snoochers

fattire said:


> Additionally, at 10kHz the wavelengths are _tiny_; ~0.113 inches, and they only get smaller going up. You only need to absorb absorb 1/4 - 1/2 of a wavelength (0.02825 - 0.0565 inches) to start to see absorption. I'm eyeballing some GOM FR701 right now and it's at least that thick. Any fabric used will likely have a very similar impact. Any fabric that doesn't have that impact will likely be both acoustically and visually transparent/sheer defeating the purpose for which it's being used. Unfortunately you can't have your cake and eat it too.


I do think you can somewhat have your cake and eat it too. I have a hundred yards of speaker fabric in my theatre and it is not see through at all and very transparent. I think having some GOM panels isn't an issue, but having entire walls draped in the stuff I reckon would lead to undesirable consequences. I think if a person's goal is to have maximal acoustic performance then it is worth considering the fabric carefully. That being said the average person won't be able to tell and I reckon even a trained ear might struggle sometimes.


----------



## Snoochers

nathan_h said:


> The data Toole shares is not wrong. The conclusion that this means fabric is inherently bad is wrong. What it means is you can get close and estimate how many and what kinds of panels and fabric are useful. Then you put them up and you measure the results. In particular you measure the decay times.....not a single RT60 for the room, but an RT60 for each octave of human hearing, and you see whether you have achieved your goal. If you have, great. If not, adjust things.
> 
> 
> Honestly in the Toole graphic I would prefer the "fabric" line because it is more consistent across the audible spectrum than the plain fiberglass line, which looks likely to kill the top two octaves 5k to 20k more thoroughly that I would want. I actually want very similar impact across the whole audio spectrum, which this graphic shows is easier with fabric on the panels......


Every fabric is different and the angles of measurement also lead to differences in measurement so I'd be careful saying one line is better than the other. The only thing we know is that having fabric does affect performance in unexpected ways so folks should be cautious perhaps. I don't think anyone said fabric is inherently bad


----------



## fattire

Snoochers said:


> I do think you can somewhat have your cake and eat it too. I have a hundred yards of speaker fabric in my theatre and it is not see through at all and very transparent. I think having some GOM panels isn't an issue, but having entire walls draped in the stuff I reckon would lead to undesirable consequences. I think if a person's goal is to have maximal acoustic performance then it is worth considering the fabric carefully. That being said the average person won't be able to tell and I reckon even a trained ear might struggle sometimes.


Maybe? Speaker fabric is transparent from a 90° angle, but what about 45°? That's a different use-case. I've never had the interest/need to dig for that kind of info. It might be interesting to find.


----------



## audiowarrior

Would you guys agree that an acoustically treated room is the *most important *variable? More important than speakers, amps, subs, etc.

I’m still new to all of this, but I feel like the most expensive speakers will still sound like crap in an untreated room.


----------



## sdurani

audiowarrior said:


> Would you guys agree that an acoustically treated room is the *most important *variable? More important than speakers, amps, subs, etc.
> 
> I’m still new to all of this, but I feel like the most expensive speakers will still sound like crap in an untreated room.


Typical furnishings (couches, drapes, bookshelves, etc) can be helpful in breaking up and/or absorbing reflections in a room. If you place subwoofers and good speakers (with smooth on-axis and consistent off-axis response) at locations that minimize room modes, then acoustical treatments are not a requirement (let alone the most important variable). You can always use them to sculpt the sound to your personal preference, but the set-up will sound fine without them.


----------



## fattire

audiowarrior said:


> Would you guys agree that an acoustically treated room is the *most important *variable? More important than speakers, amps, subs, etc.
> 
> I’m still new to all of this, but I feel like the most expensive speakers will still sound like crap in an untreated room.


Just to add to what Sanjay said ....

The quality of the speakers and their placement is probably the single most important thing to get right. The speakers are reproducing the sound and if they're not well designed as described by Sanjay, no amount of room treatment or electronic wizardry will fix them. Note I said "quality" not "price" as those two things aren't necessarily correlated (or perhaps only correlated to a certain point). And yes, they will likely sound fine without specific treatments and just the "stuff of life" in most rooms.

However, I personally think that acoustic treatments can provide the biggest bang-for-the-buck improvement. This is especially true for DIY acoustic treatments that can be built very inexpensively. Just picking a number ... $1,000 in room treatments will probably help more than spending another $1,000 in electronics or speakers.


----------



## Snoochers

I'm looking to build some 4" diffusers. 1D diffusers seem fairly simple and I can build vertical channels with QRDude dimensions easily enough with plywood. My concern is the 2D diffusers, and I'll probably need 8-10 of them for my room. What would be the most effective design for a 4" deep 2D (some say 3D) diffuser? I see these skyline diffusers and they seem cool but by my math I'd need to cut and glue 1100 pieces of wood approximately, which seems like an insane amount of work!


----------



## nathan_h

audiowarrior said:


> Would you guys agree that an acoustically treated room is the *most important *variable? More important than speakers, amps, subs, etc.
> 
> I’m still new to all of this, but I feel like the most expensive speakers will still sound like crap in an untreated room.


“Most“ important is a tough qualifier.

A focus on “treatment” misses the point.

I prefer the statement “the room is half the sound.” 

“The room” refers not just to appropriate decay time (eg, use of room treatment to some degree in most rooms), but also to speaker placement, listening position, bass management, probably some eq (especially below the room transition frequency), etc.

To answer your implied second question: yes I’d rather listen to good speakers setup well in a great room than great speakers set up poorly in a bad room.


----------



## Snoochers

A lot of folks are suggesting and selling 2-4" acoustic diffusers and these are perhaps effective in the 800-5000hz range and many have even narrower ranges. Dr. Toole's book mentions how diffusers generally need to be quite deep (like 8") to get down to the transition frequency of about 300hz and that the use of shallower diffusers can be problematic as they basically act as frequency filters. In other words you're diffusing some frequencies and not others and this is a problem. This makes sense in the same way that you don't want to absorb only high frequencies.

I'm confused here because 4" diffusers are popular and have been suggested to me by experts in the field (who happen to sell them I guess). Why would I want something that can diffuse only a portion of the sound spectrum? Wouldn't I be better just reflecting the full broadband or absorbing it rather than diffusing a portion of it?


----------



## nathan_h

Snoochers said:


> A lot of folks are suggesting and selling 2-4" acoustic diffusers and these are perhaps effective in the 800-5000hz range and many have even narrower ranges. Dr. Toole's book mentions how diffusers generally need to be quite deep (like 8") to get down to the transition frequency of about 300hz and that the use of shallower diffusers can be problematic as they basically act as frequency filters. In other words you're diffusing some frequencies and not others and this is a problem. This makes sense in the same way that you don't want to absorb only high frequencies.
> 
> I'm confused here because 4" diffusers are popular and have been suggested to me by experts in the field (who happen to sell them I guess). Why would I want something that can diffuse only a portion of the sound spectrum? Wouldn't I be better just reflecting the full broadband or absorbing it rather than diffusing a portion of it?


It’s a fair question and I’d love to see references to measurable room goals, akin to how Dolby publishes a guide to what the ideal content mastering room exhibits in terms of rt60 for each octave of human hearing.


----------



## fattire

Snoochers said:


> A lot of folks are suggesting and selling 2-4" acoustic diffusers and these are perhaps effective in the 800-5000hz range and many have even narrower ranges. Dr. Toole's book mentions how diffusers generally need to be quite deep (like 8") to get down to the transition frequency of about 300hz and that the use of shallower diffusers can be problematic as they basically act as frequency filters. In other words you're diffusing some frequencies and not others and this is a problem. This makes sense in the same way that you don't want to absorb only high frequencies.
> 
> I'm confused here because 4" diffusers are popular and have been suggested to me by experts in the field (who happen to sell them I guess). Why would I want something that can diffuse only a portion of the sound spectrum? Wouldn't I be better just reflecting the full broadband or absorbing it rather than diffusing a portion of it?


Most diffusors I see are 5.5" - 6.5" deep; usually Vicoustic, but sometimes Sonitus. A quick spec check shows them effective down to 600 Hz for diffusion.

One thing to keep in mind is that these may diffuse down to 600 Hz, but they will scatter lower than that. Sonitus states scattering for their diffusors starts at 350 Hz. GIK states 650 Hz for theirs (shallower design). Scattering isn't typically considered as "good" as diffusion, but scattering should still be "better" than a direct reflection from a hard, flat surface.

_(Side note - In looking at the future plans for my room, depth of room treatments has to be a consideration as well. That can be taken into account in a purpose-built room, but for folks like me converting rooms, 16" of diffusion (8" on opposing walls) could be a really hard pill to swallow. There's got to be a measure of this practicality when considering diffusion at lower frequencies as well.)_


----------



## Snoochers

fattire said:


> Most diffusors I see are 5.5" - 6.5" deep; usually Vicoustic, but sometimes Sonitus. A quick spec check shows them effective down to 600 Hz for diffusion.
> 
> One thing to keep in mind is that these may diffuse down to 600 Hz, but they will scatter lower than that. Sonitus states scattering for their diffusors starts at 350 Hz. GIK states 650 Hz for theirs (shallower design). Scattering isn't typically considered as "good" as diffusion, but scattering should still be "better" than a direct reflection from a hard, flat surface.
> 
> _(Side note - In looking at the future plans for my room, depth of room treatments has to be a consideration as well. That can be taken into account in a purpose-built room, but for folks like me converting rooms, 16" of diffusion (8" on opposing walls) could be a really hard pill to swallow. There's got to be a measure of this practicality when considering diffusion at lower frequencies as well.)_


Honestly I have doubts about some of those numbers. QRDude shows diffusing down to 1000hz for something that deep and I have doubts they've found some kind of secret sauce to dig that much deeper than a quadratic diffuser. That being said my question remains. Let's say they reach down to 500 or whatever and up to 5000, is this a good thing to be having so much of? What happens to the rest of the frequencies and how is this much better than reflecting all of it? All this does is diffuse some of it. Is it OK to not diffuse under 500 and over 5000? Are these qualitatively different frequencies that don't require diffusion?

I'm wondering if I should leave things bare, go with 4" diffusion, or go with 4" absorption. I will have plenty of absorption already and some deep diffusion but still lots of bare wall left.


----------



## fattire

Snoochers said:


> Honestly I have doubts about some of those numbers. QRDude shows diffusing down to 1000hz for something that deep and I have doubts they've found some kind of secret sauce to dig that much deeper than a quadratic diffuser. That being said my question remains. Let's say they reach down to 500 or whatever and up to 5000, is this a good thing to be having so much of? What happens to the rest of the frequencies and how is this much better than reflecting all of it? All this does is diffuse some of it. Is it OK to not diffuse under 500 and over 5000? Are these qualitatively different frequencies that don't require diffusion?
> 
> I'm wondering if I should leave things bare, go with 4" diffusion, or go with 4" absorption. I will have plenty of absorption already and some deep diffusion but still lots of bare wall left.


I'd like to see a study showing a distribution of RT in 1/3 octave bands for like 1,000 rooms. Is there a common "shape" that they follow indicating some frequencies are more problematic from an RT time than others? I haven't measured very many rooms, but for the 10 or so I have, there is definitely a common shape. Specific RT values vary by room size, but the shape is pretty consistent.

I think that type of study/data might have the information to help us understand better.


EDIT:


Snoochers said:


> I'm wondering if I should leave things bare, go with 4" diffusion, or go with 4" absorption. I will have plenty of absorption already and some deep diffusion but still lots of bare wall left.


I'll be in the same boat as you here in a month or so. It will be time to get serious about my room treatments vs just some direct treatment of known problem reflections via absorption. I'll be interested in seeing what you learn.


----------



## Snoochers

fattire said:


> I'd like to see a study showing a distribution of RT in 1/3 octave bands for like 1,000 rooms. Is there a common "shape" that they follow indicating some frequencies are more problematic from an RT time than others? I haven't measured very many rooms, but for the 10 or so I have, there is definitely a common shape. Specific RT values vary by room size, but the shape is pretty consistent.
> 
> I think that type of study/data might have the information to help us understand better.
> 
> 
> EDIT:
> 
> I'll be in the same boat as you here in a month or so. It will be time to get serious about my room treatments vs just some direct treatment of known problem reflections via absorption. I'll be interested in seeing what you learn.


I want some answers man! Lol


----------



## nathan_h

fattire said:


> I'd like to see a study showing a distribution of RT in 1/3 octave bands for like 1,000 rooms. Is there a common "shape" that they follow indicating some frequencies are more problematic from an RT time than others? I haven't measured very many rooms, but for the 10 or so I have, there is definitely a common shape. Specific RT values vary by room size, but the shape is pretty consistent.
> 
> I think that type of study/data might have the information to help us understand better.
> 
> 
> EDIT:
> 
> I'll be in the same boat as you here in a month or so. It will be time to get serious about my room treatments vs just some direct treatment of known problem reflections via absorption. I'll be interested in seeing what you learn.


There were standards rolled out for mastering suites but it’s not clear whether anyone has measured a lot of rooms and would share that data.…..or that it would represent a target or just a historical record that shouldn’t be a target because they were trying to reach a target and just had to compromise to greater or lesser degreees?

Someone like Grimani or Erskine ostensibly has measurements for hundreds (or thousands) of rooms over the last two decades. I can’t imagine them sharing that data.


----------



## sdurani

nathan_h said:


> There were standards rolled out for mastering suites but it’s not clear whether anyone has measured a lot of rooms and would share that data.…..


From an old (pre-Atmos) paper by Newell:









They do try to hug the target curve, but there is plenty of inconsistency considering these are professional work spaces.


----------



## nathan_h

sdurani said:


> From an old (pre-Atmos) paper by Newell:
> View attachment 3303105
> 
> 
> They do try to hug the target curve, but there is plenty of inconsistency considering these are professional work spaces.



Very cool. Do you know the link or name of the paper?

Did they measure decay times, which is what we are trying to get at (I think)?

Of course, given that they are "Dolby Certified Dubbing Theaters" we can sort of surmise they cluster around the Dolby targets, I suppose.


----------



## sdurani

nathan_h said:


> Do you know the link or name of the paper?


Going off memory, but I think it was _'Cinema Sound: A New Look At Old Concepts'_. Here's the abstract:


> The use of third-octave-band equalisation for 'room' correction and other compensations in cinema studios and public cinemas is virtually de rigueur. Nevertheless, the understanding of psycho-acoustics and audio signal processing has advanced enormously in the almost 40 years since the current concepts of cinema equalisation were introduced, yet some perhaps out-dated procedures still prevail. To some degree, this has been necessary to maintain the standardisation and continuity in the industry, but it has also limited the ability to make significant advances in soundtrack quality. Given what we now know, along with the imminent introduction of Digital Cinema, an opportunity seems to be presenting itself for taking a new look at the strengths and weaknesses of cinema set-up procedures. The responses of 30 Dolby certified cinema rooms, both mixing studios and public theatres, were measured at the recommended reference distance and close to the central loudspeakers. From comparisons of the near and far responses it has been possible to assess how much the direct sound in typical theatres is being compromised in order to meet the notional standardisation of responses. The ramifications of these compromises are discussed.


I don't remember if they measured decay time. I was simply pointing out that mix rooms (dubbing stages) and commercial movie theatres can have a hard time sticking to industry standards.


----------



## fastninja76

Any of you guys have experience with acoustically treating a square room?? I know the square shape is definitely not ideal, but a 13x13x8 room is what I have to work with. 

I figured I’d be buying a LOT of acoustic panels, but I’d like to know the most effective places to install them.


Sent from my iPhone using Tapatalk


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## sdurani

Before buying panels, I would use placement to address the peaks & nulls in your room that will occur at certain problem frequencies (43Hz, 87Hz, 130Hz, etc). A pair of subs centered at 1/4 and 3/4 points of room width. L/C/R speakers centered at 1/6, 3/6 and 5/6 points of room width. Listeners' ears (not seat backs) at 2/3 room length from the front wall. This will help get better bass response (fewer/smaller peaks & dips, with good consistency from seat to seat). Aside from that, your square room can be treated like any rectangular room.


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## nathan_h

fastninja76 said:


> Any of you guys have experience with acoustically treating a square room?? I know the square shape is definitely not ideal, but a 13x13x8 room is what I have to work with.
> 
> I figured I’d be buying a LOT of acoustic panels, but I’d like to know the most effective places to install them.
> 
> 
> Sent from my iPhone using Tapatalk


@sdurani has good advice for you, but I will make it even more simple:

A square room is not the horror we all once thought. 

In fact, if you look at the harman research on subwoofers, and listen to Todd Welti talk about square rooms, there is a simple solution: Four subs, placed intentionally to deal with room modes. He recommends the corners, for a square room. (You might be able to get away with two subs. But it is a little more tricky since it limits your options with seat placement.)

You can listen to Todd Welti talk about this and related audio topics here: AV Rant #737: Interview with Todd Welti on Subwoofers - AV Rant

Or watch it as a video, here: AVRant Podcast #737 - Interview with Todd Welti on Subwoofers

Now, all that is basically about the sub woofer range. But that is where most of the room modes are, so that gets you a long way towards good management of room modes. (And it takes a ton of very thick room treatments to impact room modes since the wavelengths are so long, so be thankful you can do it with active treatment in the form of multiple subs.)

Which is to say: yes you will still benefit from room treatments, and not sitting against a wall. But you can get away with 4" thick (I'd try for six inch thick) panels, once you have "solved" room modes via multiple subs (and EQ).


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## Snoochers

Finally finished with sound absorption in my home theater. Can some of you comment on these reverberation measurements? I forget which lines are most important so I included them all.


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## fattire

Snoochers said:


> Finally finished with sound absorption in my home theater. Can some of you comment on these reverberation measurements? I forget which lines are most important so I included them all.


I think those look great. The specific value of things like T20/T30 is less important than how smooth the shape of the curve is. Bigger rooms naturally have higher times than smaller rooms, as an example. Yours certainly looks very good. I have a similar hump in that 100-200 Hz range. I honestly don't know if it's detrimental to the overall sound, but I don't have any issues with it (or just don't know any better! LOL!). In my room that hump is caused by the same thing - the dip at 250 Hz.

Your low-end in the waterfall is VERY well controlled. I wish mine looked like that for sure!

I'd love to see @nathan_h weigh in on this too.


----------



## Snoochers

fattire said:


> I think those look great. The specific value of things like T20/T30 is less important than how smooth the shape of the curve is. Bigger rooms naturally have higher times than smaller rooms, as an example. Yours certainly looks very good. I have a similar hump in that 100-200 Hz range. I honestly don't know if it's detrimental to the overall sound, but I don't have any issues with it (or just don't know any better! LOL!). In my room that hump is caused by the same thing - the dip at 250 Hz.
> 
> Your low-end in the waterfall is VERY well controlled. I wish mine looked like that for sure!
> 
> I'd love to see @nathan_h weigh in on this too.


Oh that means a lot. I don't know much about this stuff so just kind of did what I thought made sense based on what I've seen online. 200ms seems a bit on the dead side of things but hopefully it is ok. I wouldn't trust my ears to decide what is good vs what isn't.


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## fattire

Snoochers said:


> Oh that means a lot. I don't know much about this stuff so just kind of did what I thought made sense based on what I've seen online. 200ms seems a bit on the dead side of things but hopefully it is ok. I wouldn't trust my ears to decide what is good vs what isn't.


Same here - I just haven't been in enough rooms. It also helps me personally to see measurements to help quantify what I'm hearing. So many variables. My curve is as low as 200 ms and as high as 350 ms.

I need to find the doc/reference, but one of the better known acoustic consultants (Acoustic Frontiers maybe?) has a good doc on the goal for these measurements. They're something like 200 - 500 ms with no more than a 25% difference between adjacent 1/3 octave bands. I think it's easier to see if you use the "bars on plot" options under the graph controls. They also have a recommended frequency range for those values. Like 500 Hz - 4 or 8 kHz or similar. 250 kHz - 4 kHz. Found the paper see below! I'll see if I can find the doc again and post a link here. It's a good read.

_(EDIT: My memory served me correctly for a change. __Here's the doc__.)_


----------



## nathan_h

Yes I would be pleased with those results.

There is a way to generate actual RT60 graphs in REW but in domestic rooms it likely looks very much like your T30.



> Here's the process:
> 
> Open up an mdat with full range measurements of your L+R
> Select a measurement on the left, then go to "RT60 Decay" window
> The graphs will (probably) be empty
> Hit the "Generate" button in the bottom left of the bottom graph
> Hit the "Controls" gear
> Hit "Calculate RT60 Model"
> Now, go to the regular RT60 window. The measurement you used above will now have an RT60 . This is also supported in the "Overlays" graphs making it super easy to compare before/after. In my room, the T30 and calculated RT60 are extremely close to one another.


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## nathan_h

Here is the Dolby standard for mastering rooms:


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## Snoochers

nathan_h said:


> Here is the Dolby standard for mastering rooms:
> 
> View attachment 3310045


Oh thanks, that is what I was looking for! I seem to be around there so I'm happy. A bit dead maybe but not terribly slow.


----------



## Snoochers

This is my SPL chart for L and R from REW with my KEF R7s with 1/3 smoothing. Seems a bit rough? Or not? With ARC EQ


----------



## nathan_h

Snoochers said:


> This is my SPL chart for L and R from REW with my KEF R7s with 1/3 smoothing. Seems a bit rough? Or not? With ARC EQ
> View attachment 3311470


Try psychoacoustic smoothing in REW.

Also maybe post the non ARC measurement too?


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## fattire

Snoochers said:


> This is my SPL chart for L and R from REW with my KEF R7s with 1/3 smoothing. Seems a bit rough? Or not? With ARC EQ
> View attachment 3311470


Your scale on the left is super narrow. We typically use a 5 dB scale. If I imagine a target curve running through there, I think it looks pretty good. Probably +/- 3 dB which is excellent.

Only real concern I'd look at is the big dip around 65 Hz. That's about 8 dB peak-to-peak. If this is mains only, without subs, it's probably irrelevant depending on the crossover frequency. If there are no subs, I'd figure out how to address that; likely by moving the listening position to get out of that null.


----------



## Snoochers

fattire said:


> Your scale on the left is super narrow. We typically use a 5 dB scale. If I imagine a target curve running through there, I think it looks pretty good. Probably +/- 3 dB which is excellent.
> 
> Only real concern I'd look at is the big dip around 65 Hz. That's about 8 dB peak-to-peak. If this is mains only, without subs, it's probably irrelevant depending on the crossover frequency. If there are no subs, I'd figure out how to address that; likely by moving the listening position to get out of that null.


There are two subs on opposing walls so I don't know what is going on exactly. I will take another measurement mic with slightly different position.


----------



## nathan_h

Snoochers said:


> There are two subs on opposing walls so I don't know what is going on exactly. I will take another measurement mic with slightly different position.


It can also be helpful to measure the subs separately from the mains, to really see if the subs are setup as well as possible.


----------



## Snoochers

nathan_h said:


> It can also be helpful to measure the subs separately from the mains, to really see if the subs are setup as well as possible.


Unfortunately I don’t know how to do that. I have a simple stereo analogue cable going from my laptop to the receiver and I don’t think I have a way to get another type of cable to my listening position. I can use anthem arc wirelessly to do the subwoofer but it wouldn’t be with REW. I’ll see if I can post something.


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## nathan_h

Interesting. What kind of receiver/integrated amp/pre-pro are you using?


----------



## fattire

Snoochers said:


> Unfortunately I don’t know how to do that. I have a simple stereo analogue cable going from my laptop to the receiver and I don’t think I have a way to get another type of cable to my listening position. I can use anthem arc wirelessly to do the subwoofer but it wouldn’t be with REW. I’ll see if I can post something.


If your subs are fed from the LFE channel, you can temporarily connect them to the R channel pre-out and disconnect the speaker. Then sweep the subs using the R channel. Be sure to use a timing reference played on the L channel so the measurements are actionable in REW if needed. To sweep subs individually, just mute one somehow (power off, disconnect, etc), measure the other and repeat the process with the other sub.

We'd need to know the answer to nathan_h's question above as well - the actual signal chain could impact this ^^ recommendation.


----------



## Snoochers

nathan_h said:


> Interesting. What kind of receiver/integrated amp/pre-pro are you using?


I’m using an MRX1140 with an inuke6000 for the subs. I have a simple 3.5 mm stereo cable going from the receiver to my main listening position. But otherwise I don’t have a cable going back-and-forth. Anthem Arc works wirelessly which is nice.


----------



## Snoochers

nathan_h said:


> It can also be helpful to measure the subs separately from the mains, to really see if the subs are setup as well as possible.


Here are the sub measurements from Anthem ARC. The last two are my L and R.


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## nathan_h

I'd recommend using the HDMI output from the laptop, which will let you use REW for specific speakers much more easily. You also remove the possibility that the analog output of your laptop and the analog input of your AVR are introducing errors.


----------



## Snoochers

nathan_h said:


> I'd recommend using the HDMI output from the laptop, which will let you use REW for specific speakers much more easily. You also remove the possibility that the analog output of your laptop and the analog input of your AVR are introducing errors.


I could probably find a way if my laptop had HDMI LOL. Stupid MacBook.


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## nathan_h

Yeah, I had to get a USBC-HDMI dongle for one machine.


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## fattire

Snoochers said:


> I could probably find a way if my laptop had HDMI LOL. Stupid MacBook.


I rage purchased an M1 MacBook Pro because of this. LOL. I feel your pain!


----------



## Snoochers

nathan_h said:


> Yeah, I had to get a USBC-HDMI dongle for one machine.


Do you think the anthem ARC readings are sufficiently accurate? Those can be done wirelessly so easy enough. I included measurements above.


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## nathan_h

I don’t know a way to use ARC to measure ARC. I’ve only seen it show pre-ARC measurements and estimates of the post ARC response. So what you’ve got are some basic graphs of the in room response. But I thought you were asking bout your ARC results? Sorry, I am not sure what you are trying to do.


----------



## DJ_Stix

I asked over on the DIY side, but thought this group might be able to provide advice. 

I have Vortex 12's (DIYSG 12" coaxials) that I am using for surrounds and will use them as an in-wall installation. I already have DIY absorbers with 2" thick OC703 (covered in GOM fabric) at reflection points along the side walls. For best appearance, and protection, I want to use an additional "dummy" panel to hang over top where the V12 is mounted to hide it. 

My question is, should I:

make another absorber (2' x 4' OC703) and then just cut like a 13" hole in it where the V12 is? there are first reflection points right in this area, so getting more absorption would be good, but I don't know if having the speaker surrounded by this would effect directivity and sound?
Create a mounting ring that brings the face of the speaker out 2" from the wall so that the speaker mounts flush with the OC703, and then do above?
make a 2' x 4' panel but empty (with no OC703). I am worried about appearance and the GOM fabric not looking the same since it wouldn't have any support behind it.

Any input is greatly appreciated.


----------



## nathan_h

DJ_Stix said:


> I asked over on the DIY side, but thought this group might be able to provide advice.
> 
> I have Vortex 12's (DIYSG 12" coaxials) that I am using for surrounds and will use them as an in-wall installation. I already have DIY absorbers with 2" thick OC703 (covered in GOM fabric) at reflection points along the side walls. For best appearance, and protection, I want to use an additional "dummy" panel to hang over top where the V12 is mounted to hide it.
> 
> My question is, should I:
> 
> make another absorber (2' x 4' OC703) and then just cut like a 13" hole in it where the V12 is? there are first reflection points right in this area, so getting more absorption would be good, but I don't know if having the speaker surrounded by this would effect directivity and sound?
> Create a mounting ring that brings the face of the speaker out 2" from the wall so that the speaker mounts flush with the OC703, and then do above?
> make a 2' x 4' panel but empty (with no OC703). I am worried about appearance and the GOM fabric not looking the same since it wouldn't have any support behind it.
> 
> Any input is greatly appreciated.


1. might be problematic. I would prefer option 2.
2. this should work fine. I cannot speak to whether you need more absorption for high frequencies in this room. You would need to post your REW RT60 measurements to get an idea of whether that is the case.
3. this should work. I cannot speak to whether it will look the same but it is easy to test.

By the way, not all GOM is really acoustically transparent enough for a speaker to be behind it. IIRC the Anchorage one in particular attenuates the high frequencies.


----------



## DJ_Stix

nathan_h said:


> 1. might be problematic. I would prefer option 2.
> 2. this should work fine. I cannot speak to whether you need more absorption for high frequencies in this room. You would need to post your REW RT60 measurements to get an idea of whether that is the case.
> 3. this should work. I cannot speak to whether it will look the same but it is easy to test.
> 
> By the way, not all GOM is really acoustically transparent enough for a speaker to be behind it. IIRC the Anchorage one in particular attenuates the high frequencies.


I appreciate your input and agree. Will probably do 2 with a bevel on the insulation if necessary. Thank you! 

I looked up my old order and this is actually the material I have:









FR Executive Fire Rated Acoustic Fabric by The Yard 58" Wide


Fire Rated Acoustically transparent acoustic fabric with a microsuede texture.3 Yard Minimum per order🔥 CLASS-A FIRE RATED FABRIC💾 CLICK TO DOWNLOAD TEST RESULTS




www.acoustimac.com


----------



## nathan_h

DJ_Stix said:


> I appreciate your input and agree. Will probably do 2 with a bevel on the insulation if necessary. Thank you!
> 
> I looked up my old order and this is actually the material I have:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> FR Executive Fire Rated Acoustic Fabric by The Yard 58" Wide
> 
> 
> Fire Rated Acoustically transparent acoustic fabric with a microsuede texture.3 Yard Minimum per order🔥 CLASS-A FIRE RATED FABRIC💾 CLICK TO DOWNLOAD TEST RESULTS
> 
> 
> 
> 
> www.acoustimac.com


IIRC that fabric measures fine for putting in front of a speaker. 

The only fabric I recall being a problem at Acoustimac is their suede fabric, which is okay for panels but not transparent enough for putting in front of a speaker based on the REW measurements that have been posted on AVS in the past. (They even acknowledge this a bit in a round about way by noting that if you use in on panels you will need MORE panels in the room since the suede is more reflective and doesn't let as much sound get through to the insulation underneath.)


----------



## Snoochers

How do I get REW to send signals to my two subs separately? I see only an LFE option with my HDMI which seems to hit both. I'm on OSX for what it's worth.


----------



## fattire

Snoochers said:


> How do I get REW to send signals to my two subs separately? I see only an LFE option with my HDMI which seems to hit both. I'm on OSX for what it's worth.


You can't unless the AVR/Processor allows you to mute the outputs independently. I'd recommend just turning one off, measuring, then do that with the other.


----------



## Snoochers

fattire said:


> You can't unless the AVR/Processor allows you to mute the outputs independently. I'd recommend just turning one off, measuring, then do that with the other.


Thanks I did this. This is what I got. Huge null around 65hz that I can't get rid of. I don't understand that since the subts seem fine? LCRs and subs shown in the photo. I move crossover and LFE all over the place and the null is still there. My LCR shouldn't be playing much around 65hz and my subs seem fine so I don't understand the cause of it.


----------



## fattire

Snoochers said:


> Thanks I did this. This is what I got. Huge null around 65hz that I can't get rid of. I don't understand that since the subts seem fine? LCRs and subs shown in the photo. I move crossover and LFE all over the place and the null is still there. My LCR shouldn't be playing much around 65hz and my subs seem fine so I don't understand the cause of it.
> View attachment 3313220


Probably not the right thread to troubleshoot this, and we don't want to get too far off topic.

There's a great thread here with folks that are super helpful and very responsive: Guide to Subwoofer Calibration and Bass Preferences


----------



## nathan_h

True that almost certainly not caused by room treatments nor solvable by conventional treatments.


----------



## Nick V

Finally got the rear wall in my small JBL Synthesis Media Room system treated with Vicoustic Multifuser DC3 diffusers.

There are also 2" GIK Acoustics Art Panels taking care of the early first reflections off the rear wall from the SCL-7 in-wall surround speakers. There are also Monster Bass traps in each of the rear corners horizontally, along the floor/wall junction.


----------



## dwander

I have to build a new grill for the compartment that houses two of my subs. The current one has cheap parts express speaker grill clothe which I’m fine with but just don’t have any on hand. I do have a bunch of DMD AT fabric though. So, I’m considering three options: using the DMD, buying some more of the cheap stuff, or spending a little extra on some premium speaker grill clothe. Look wise the DMD would probably be best since it will match my walls, but I want to give first consideration to whichever option will be best for letting the sound through.


----------



## fattire

dwander said:


> I have to build a new grill for the compartment that houses two of my subs. The current one has cheap parts express speaker grill clothe which I’m fine with but just don’t have any on hand. I do have a bunch of DMD AT fabric though. So, I’m considering three options: using the DMD, buying some more of the cheap stuff, or spending a little extra on some premium speaker grill clothe. Look wise the DMD would probably be best since it will match my walls, but I want to give first consideration to whichever option will be best for letting the sound through.


For subs, it won't matter. You could use that super heavy blackout velvet and there would be no impact on the bass from the other side. The wavelengths are too long.


----------



## anjunadeep

I'm building a false forward and rear wall in my theater, and I have some old acoustic panels on hand. 

Question: Is it okay to have wrapped (Guilford of Maine) acoustic panels BEHIND a false (acoustic clothe, also guilford) wall? So basically the sound would pass through the false wall (Guilford of Maine acoustic clothe) and then hit a Guilford of Maine wrapped standing panel?










I have a few panels "in inventory" that would be great to use up, but if the sound passing through two fabric layers is an issue then I'd probably just put Roxel back there instead. One thought was that there might be some benefit to this being freestanding though, since maybe it can absorb a bit deeper into the lower midrange. (it's 4" thick and open in the back)


----------



## dwander

anjunadeep said:


> I'm building a false forward and rear wall in my theater, and I have some old acoustic panels on hand.
> 
> Question: Is it okay to have wrapped (Guilford of Maine) acoustic panels BEHIND a false (acoustic clothe, also guilford) wall? So basically the sound would pass through the false wall (Guilford of Maine acoustic clothe) and then hit a Guilford of Maine wrapped standing panel?
> 
> View attachment 3322737
> 
> 
> I have a few panels "in inventory" that would be great to use up, but if the sound passing through two fabric layers is an issue then I'd probably just put Roxel back there instead. One thought was that there might be some benefit to this being freestanding though, since maybe it can absorb a bit deeper into the lower midrange. (it's 4" thick and open in the back)


Ive got some DIY bass traps added after the fact behind a false fabric wall and they made a significant difference. The bass traps arent wrapped in fabric but I cant see why that would matter.


----------



## anjunadeep

dwander said:


> Ive got some DIY bass traps added after the fact behind a false fabric wall and they made a significant difference. The bass traps arent wrapped in fabric but I cant see why that would matter.


Thanks. Yeah I was more concerned if the sound waves passing through two layers of acoustic clothe might cause it to not work as well in a meaningful manner. Worst comes to worst I just removed the upholstery from the existing panels, but, it's always nicer to leave them wrapped - plus since it's free standing I don't have to drill into the rear wall.


----------



## dwander

anjunadeep said:


> Thanks. Yeah I was more concerned if the sound waves passing through two layers of acoustic clothe might cause it to not work as well in a meaningful manner. Worst comes to worst I just removed the upholstery from the existing panels, but, it's always nicer to leave them wrapped - plus since it's free standing I don't have to drill into the rear wall.


I only have it not wrapped out of laziness. Its probably the laziest bass traps ever made. Then I just threw some plastic drops over the top of my rear speakers so they didnt get fiberglass on them. But I would have definitely wrapped them had I wanted to do it right.


----------



## anjunadeep

dwander said:


> I only have it not wrapped out of laziness. Its probably the laziest bass traps ever made. Then I just threw some plastic drops over the top of my rear speakers so they didnt get fiberglass on them. But I would have definitely wrapped them had I wanted to do it right.


Thanks. For bass I would imagine it would be no issue having two layers to pass through, I'm more worried about the high frequencies... If I do corner bass traps it's unlikely I'd wrap them just because roxel keeps together pretty well and is already dark.


----------



## dwander

anjunadeep said:


> Thanks. For bass I would imagine it would be no issue having two layers to pass through, I'm more worried about the high frequencies... If I do corner bass traps it's unlikely I'd wrap them just because roxel keeps together pretty well and is already dark.


I’d still think it would be fine. If the sound goes through then it’s gonna through until it’s absorbed. Don’t think it would cause a reflection or anything like that. Even the highs.


----------



## nathan_h

anjunadeep said:


> I'm building a false forward and rear wall in my theater, and I have some old acoustic panels on hand.
> 
> Question: Is it okay to have wrapped (Guilford of Maine) acoustic panels BEHIND a false (acoustic clothe, also guilford) wall? So basically the sound would pass through the false wall (Guilford of Maine acoustic clothe) and then hit a Guilford of Maine wrapped standing panel?
> 
> View attachment 3322737
> 
> 
> I have a few panels "in inventory" that would be great to use up, but if the sound passing through two fabric layers is an issue then I'd probably just put Roxel back there instead. One thought was that there might be some benefit to this being freestanding though, since maybe it can absorb a bit deeper into the lower midrange. (it's 4" thick and open in the back)


Use them all back there. No problem with two layers of fabric.

If you can space them off the solid wall do so as much as possible. This helps them impact a wider range of frequencies on the low end and you lose nothing on the high end.


----------



## i3ossman

Anyone using Dennis Foley (Acoustic Fields) acoustic foam? Supposedly it absorbs much better from 100hz-500hz than the traditional treatments. 









Acoustic Foam StudioPro | Premium Foam by Acoustic Fields


Get the most out of your vocals and music with the acoustic foam StudioPro by Acoustic Fields. Smoother absorption curve from 125 – 500 Hz.




www.acousticfields.com





$1500 for 180sq/ft at 2" thick


----------



## anjunadeep

i3ossman said:


> Anyone using Dennis Foley (Acoustic Fields) acoustic foam? Supposedly it absorbs much better from 100hz-500hz than the traditional treatments.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Acoustic Foam StudioPro | Premium Foam by Acoustic Fields
> 
> 
> Get the most out of your vocals and music with the acoustic foam StudioPro by Acoustic Fields. Smoother absorption curve from 125 – 500 Hz.
> 
> 
> 
> 
> www.acousticfields.com
> 
> 
> 
> 
> 
> $1500 for 180sq/ft at 2" thick


lmao at those prices there. Could have a master cabinet maker make build a bass trap cheaper than they want. My favorite is over 1000 bucks for plans for a DIY bass trap.... that's an expensive google search! 

Just use some rockwool or something man.


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## anjunadeep

If I want to convert a normal bass trap into a foil/membrane bass trap, what do I cover the trap with? plastic or maybe vinyl?


----------



## nathan_h

i3ossman said:


> Anyone using Dennis Foley (Acoustic Fields) acoustic foam? Supposedly it absorbs much better from 100hz-500hz than the traditional treatments.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Acoustic Foam StudioPro | Premium Foam by Acoustic Fields
> 
> 
> Get the most out of your vocals and music with the acoustic foam StudioPro by Acoustic Fields. Smoother absorption curve from 125 – 500 Hz.
> 
> 
> 
> 
> www.acousticfields.com
> 
> 
> 
> 
> 
> $1500 for 180sq/ft at 2" thick


Just to be clear, their claim is it is better than some of the foam that others sell for less money. Emphasis on the word "claim" since the graphs don't actually have all the measurement data one would need to compare fairly. Emphasis on the "foam". Emphasis on the word "money." And on "fairly." I would ask them for the detailed third party measurements before ordering. If they check out (ie, real certified lab, not doing something funky like testing when straddling a corner or sitting off the wall) then they wouldn't be a bad choice for treble treatment. I wouldn't choose something measuring that way for bass.

They claim "It absorbs 30% at 125 Hz., 63% at 250 Hz. and 100% at 500 Hz."

Compare that with (random easy example) GIK's flex range bass trap panels which are at 89% at 125hz (or at 100% if straddling a corner, which may be how AF measured their stuff, who knows since they don't share the technical details of their testing that I can see). If bass is what you want to work on, the GIK would be a better choice.

Okay so maybe that's not a great comparison since those GIK panels are c. $1900 for the same coverage, and they are 5.35" thick. But here's the thing, *you only need 1/3 as many of the GIK panels to trap the same amount of bass* (and maybe even less if the AF testing criteria were not as strict as GIK's third party testing). So GIK does the job for under $650 while AF does the job for $1500 in the bass regions.

But what about comparing foam? Turns out, GIK foam hits 27% at 125 hz, 63% at 250hz and 98% at 500hz (100% slightly thereafter) which is arguably just as good as what AF claims (actually better in some instances). I'm not sure why AF quotes something completely different that GIK doesn't sell.










Of course, GIK only offers their foam with a scattering plate on it (looks nice AND makes sure you don't have too much treble absorption) which makes it more expensive than AF so if you must have foam and must have it cheap, GIK might not be the best choice.

But if price for performance is what matters, something like the GIK 424 panel (or the same technology at other places like Acoustimac) does WAY better than the foam at AF (and GIK) in a similar form factor, for a similar price....


----------



## i3ossman

nathan_h said:


> Just to be clear, their claim is it is better than some of the foam that others sell for less money. Emphasis on the word "claim" since the graphs don't actually have all the measurement data one would need to compare fairly. Emphasis on the "foam". Emphasis on the word "money." And on "fairly." I would ask them for the detailed third party measurements before ordering. If they check out (ie, real certified lab, not doing something funky like testing when straddling a corner or sitting off the wall) then they wouldn't be a bad choice for treble treatment. I wouldn't choose something measuring that way for bass.
> 
> They claim "It absorbs 30% at 125 Hz., 63% at 250 Hz. and 100% at 500 Hz."
> 
> Compare that with (random easy example) GIK's flex range bass trap panels which are at 89% at 125hz (or at 100% if straddling a corner, which may be how AF measured their stuff, who knows since they don't share the technical details of their testing that I can see). If bass is what you want to work on, the GIK would be a better choice.
> 
> Okay so maybe that's not a great comparison since those GIK panels are c. $1900 for the same coverage, and they are 5.35" thick. But here's the thing, *you only need 1/3 as many of the GIK panels to trap the same amount of bass* (and maybe even less if the AF testing criteria were not as strict as GIK's third party testing). So GIK does the job for under $650 while AF does the job for $1500 in the bass regions.
> 
> But what about comparing foam? Turns out, GIK foam hits 27% at 125 hz, 63% at 250hz and 98% at 500hz (100% slightly thereafter) which is arguably just as good as what AF claims (actually better in some instances). I'm not sure why AF quotes something completely different that GIK doesn't sell.
> 
> View attachment 3324812
> 
> 
> Of course, GIK only offers their foam with a scattering plate on it (looks nice AND makes sure you don't have too much treble absorption) which makes it more expensive than AF so if you must have foam and must have it cheap, GIK might not be the best choice.
> 
> But if price for performance is what matters, something like the GIK 424 panel (or the same technology at other places like Acoustimac) does WAY better than the foam at AF (and GIK) in a similar form factor, for a similar price....



Awesome analysis, thank you. I am looking for foam/insulation panels I can attach to my walls at reflection points and then completely cover the entire wall with fabric. I have adequate bass trapping throughout the room so I don't plan on using anything super thick on the walls anywhere if I can help it. I am going with a mix of 1-2" of absorption and diffusion under the fabric walls on the sides/rear wall/ceiling. Based on the numbers and my application, I think AF's panels are probably the best option no? I was originally going to use OC703.


----------



## nathan_h

The AF stuff is 2.5 times as expensive as normal fiberglass or rock wool panels and less broadband so you will be paying more for panels that are less likely to give you an optimum result especially since their panels are too thin. If you double them up that might help.

The standard 3.5” fiberglass will work better and cost less in my experience especially for a first reflection point where you want consistent absorption from 20k down to as close to 100hz as possible.

Both the foam and fiberglass are 100% effective at treble. 

The foam however is less than half as effective in the bass. So it will be like you turned up the bass or turned down the treble with a tone control.

The fiberglass is more effective in the bass, especially in the 3.5” size, meaning it doesn’t act like a tone control nearly as much but impacts all the frequencies more evenly and consistently.


----------



## i3ossman

nathan_h said:


> The AF stuff is 2.5 times as expensive as normal fiberglass or rock wool panels and less broadband so you will be paying more for panels that are less likely to give you an optimum result especially since their panels are too thin. If you double them up that might help.
> 
> The standard 3.5” fiberglass will work better and cost less in my experience especially for a first reflection point where you want consistent absorption from 20k down to as close to 100hz as possible.
> 
> Both the foam and fiberglass are 100% effective at treble.
> 
> The foam however is less than half as effective in the bass. So it will be like you turned up the bass or turned down the treble with a tone control.
> 
> The fiberglass is more effective in the bass, especially in the 3.5” size, meaning it doesn’t act like a tone control nearly as much but impacts all the frequencies more evenly and consistently.


When you say standard fiberglass are you referring to pink fluffy R13? I could just use that on the first reflection points I suppose


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## nathan_h

More like Owens Corning 703 and similar "rigid" insulation. The floppy batts are tough to tame.


----------



## Fatawan

Please critique my riser/treatment idea if you would. I can't come up with the fancy drawings, so bear with my verbal description. My room is 13'W x 23.5'L. I will have a ~12" riser in the back, attaching to both the side walls and the back wall. I have read all the threads on risers as bass absorbers with vents and such, but what about this idea. If I do stacked triangular bass traps in each corner, I could leave out the top of the riser and run the triangles right onto the framing of the riser which would be filled with insulation as well. I would also leave out 4" of plywood from the strip along the back wall. I would then have my back wall treatment(Roxul?) hang over the riser framing and bump into the insulation below. I could then use fabric and trim to make it all look pretty. Above would be a soffit that would also be Roxul filled. The riser would have oak flooring as the top layer, so it would be simple to go around these spots. Opinions?


----------



## Dsauce281

dwander said:


> I have to build a new grill for the compartment that houses two of my subs. The current one has cheap parts express speaker grill clothe which I’m fine with but just don’t have any on hand. I do have a bunch of DMD AT fabric though. So, I’m considering three options: using the DMD, buying some more of the cheap stuff, or spending a little extra on some premium speaker grill clothe. Look wise the DMD would probably be best since it will match my walls, but I want to give first consideration to whichever option will be best for letting the sound through.


I just built some covers for my inwall subs. I used a piece of 3/4" MDF cut the inside out to make a 3" frame. Wrapped it in black Guilford and stapled to the back. Added heavy duty sticky back Velcro. Looks great and super sturdy.


----------



## FreMo

Dsauce281 said:


> I just built some covers for my inwall subs. I used a piece of 3/4" MDF cut the inside out to make a 3" frame. Wrapped it in black Guilford and stapled to the back. Added heavy duty sticky back Velcro. Looks great and super sturdy.


Do you have pictures of these?


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## Dsauce281

FreMo said:


> Do you have pictures of these?


I didn't take any pictures while I was working on them unfortunately but here is the final look and the before. It's hard to see the difference but I guess that's the point. The black GoM is really great at blending into the front stage.


----------



## cricket9998

Does anyone have a tear down of the Gik range limiter plate? I am curious to see what it looks like under the fabric and what it actually "is".

Edit: ah great, they actually filed a patent so its public knowledge. You just can't copy it of course.... US9091060B2 - Sound panel and method for assembly of a sound panel - Google Patents

I can see why they patented it and also how they make it easy to absorb from the front AND side while still having a frame.


----------



## nathan_h

So basically a membrane between two layers of insulation?


----------



## cricket9998

nathan_h said:


> So basically a membrane between two layers of insulation?


Just from what’s written on the patent (public info don’t sue me)

It’s 0.5 pounds of MLV which sits on top of 2-4” of fiberglass and a wooden frame behind it for an air gap, and the another frame around the entire thing covered by fabric? They call it a membrane but it’s not the same as a limp membrane resonator. It just blocks high frequencies.


----------



## nathan_h

That’s disappointing. I was under the impression they tuned them to be more effective at lower frequencies. It this is basically like adding cardboard to the front of a panel to reflect back higher frequencies. Useful but not too innovative.


----------



## cricket9998

nathan_h said:


> That’s disappointing. I was under the impression they tuned them to be more effective at lower frequencies. It this is basically like adding cardboard to the front of a panel to reflect back higher frequencies. Useful but not too innovative.


They have tuned membranes called scopus. It is insanely overpriced since they are small and you need a ton so I might build my own once I finish other treatments and measure again.


----------



## Dsauce281

Anyone know where to buy .5lbs mlv?


----------



## kfh227

So, I was wondering going to do some in ceiling acoustical treatment. I need removable panels to so why not make some sound absorption. 

Room is 14 feet wide and 18 feet deep. I was going to put two 32" wide panels about 6 feet and 12 feet from the front wall. The second at 12 feet will have atmos overheads. So that one is going to be installed. 

Thoughts?


----------



## nathan_h

kfh227 said:


> So, I was wondering going to do some in ceiling acoustical treatment. I need removable panels to so why not make some sound absorption.
> 
> Room is 14 feet wide and 18 feet deep. I was going to put two 32" wide panels about 6 feet and 12 feet from the front wall. The second at 12 feet will have atmos overheads. So that one is going to be installed.
> 
> Thoughts?


What is an "in ceiling" treatment? What kind of ceiling is it? Drop tile?

What other treatments are in the room?

What will the panels be made of? How thick? When you say "32 inches wide" are they square?


----------



## anjunadeep

Is there a chart on how deep you need to go to influence bass frequencies with bass trapping? I've only found things up to 6", but is there a formula or chart that shows if you want to attack lower frequencies like 50Hz or even 40Hz?


----------



## cricket9998

anjunadeep said:


> Is there a chart on how deep you need to go to influence bass frequencies with bass trapping? I've only found things up to 6", but is there a formula or chart that shows if you want to attack lower frequencies like 50Hz or even 40Hz?


You cant reasonably kill frequencies that low with velocity absorbers. You will need tuned membrane absorbers for anything under 100hz or so


----------



## nathan_h

I haven't seen lab data. (And its just not about thickness, but also mass (density).). 

But in the real world, the next step is often 16" batts stacked floor to ceiling (like behind a false wall and or above a false ceiling). And then measuring the impact and adjusting as needed. 

The other popular solution: active absorbers (ie, multiple subs) for the under 100 hz region. In fact, people like Grimani stopped making their fancy sub 100 hz traps because they cost as much to make as buying an additional subwoofer, which usually worked just as well.

-----

If there is ONLY a specific frequency that is a problem then a tuned trap for that frequency is often used. But I infer you are asking about something else.


----------



## cricket9998

nathan_h said:


> I haven't seen lab data. (And its just not about thickness, but also mass (density).).
> 
> But in the real world, the next step is often 16" batts stacked floor to ceiling (like behind a false wall and or above a false ceiling). And then measuring the impact and adjusting as needed.
> 
> The other popular solution: active absorbers (ie, multiple subs) for the under 100 hz region. In fact, people like Grimani stopped making their fancy sub 100 hz traps because they cost as much to make as buying an additional subwoofer, which usually worked just as well.
> 
> -----
> 
> If there is ONLY a specific frequency that is a problem then a tuned trap for that frequency is often used. But I infer you are asking about something else.


Yeah more subs is the better and easier way. The rule of thumb for absorption is you need something equal to a quarter wavelength. 40hz would be about 7’ so you need that much velocity absorption lol. That’s about 3000$ in safe n sound alone and probably wouldn’t even fix the problem.


----------



## anjunadeep

cricket9998 said:


> You cant reasonably kill frequencies that low with velocity absorbers. You will need tuned membrane absorbers for anything under 100hz or so


It looks like 17" thick is fairly effective down to 70Hz or so, at least based on the GIK soffit trap data.


----------



## mikela

anjunadeep said:


> Is there a chart on how deep you need to go to influence bass frequencies with bass trapping? I've only found things up to 6", but is there a formula or chart that shows if you want to attack lower frequencies like 50Hz or even 40Hz?


You can use this porous absorption tool to model the response for any depth you choose.


----------



## cricket9998

I want to make corner bass traps but I don’t want it to absorb frequencies over let’s say 300hz. What material can I put in front of the absorber to block those? Really thin plywood? Something I can get at Home Depot would be great.


----------



## CincyNick

Has anyone tried the HL Velvet for acoustic panels that @PixelPusher15 tested in a thread a while back? I'm trying to get a good mix of "as black as possible" while also making sure I'm treating the room. Most of the stuff I've seen from GOM and other places looks dark gray in comparison.


----------



## cricket9998

CincyNick said:


> Has anyone tried the HL Velvet for acoustic panels that @PixelPusher15 tested in a thread a while back? I'm trying to get a good mix of "as black as possible" while also making sure I'm treating the room. Most of the stuff I've seen from GOM and other places looks dark gray in comparison.


Acoustic DMD black is very non reflective. I have it on most of my wall. Not as black as velvet but it’s acoustically transparent. Velvet will reflect high frequencies unless you perf it yourself.


----------



## PixelPusher15

CincyNick said:


> Has anyone tried the HL Velvet for acoustic panels that @PixelPusher15 tested in a thread a while back? I'm trying to get a good mix of "as black as possible" while also making sure I'm treating the room. Most of the stuff I've seen from GOM and other places looks dark gray in comparison.


I’m using it on all my acoustic panels. If anything, I’d bet it’s better than GOM when sound hits it at an angle which some fabrics actually deflect in that case.


----------



## nathan_h

CincyNick said:


> Has anyone tried the HL Velvet for acoustic panels that @PixelPusher15 tested in a thread a while back? I'm trying to get a good mix of "as black as possible" while also making sure I'm treating the room. Most of the stuff I've seen from GOM and other places looks dark gray in comparison.


Acoustically for panels I wouldn’t worry about the difference. It will be within the margin of error for most estimates on the number of panels to put in your room.

With either as panel covering, to get more precise results in the room, you will need to measure the room with REW and then decide on whether to add or subtract panels or modify some to favor some frequencies.

In front of speakers I would choose DMD or GOM (and note not all GOM is neutral acoustically so avoid some) like with fabric walls….especially for the fire retardant nature of DMD and GOM.


----------



## PixelPusher15

nathan_h said:


> Acoustically for panels I wouldn’t worry about the difference. It will be within the margin of error for most estimates on the number of panels to put in your room.
> 
> With either as panel covering, to get more precise results in the room, you will need to measure the room with REW and then decide on whether to add or subtract panels or modify some to favor some frequencies.
> 
> In front of speakers I would choose DMD or GOM (and note not all GOM is neutral acoustically so avoid some) like with fabric walls….especially for the fire retardant nature of DMD and GOM.


Did you see the testing for the HL Stretch Velvet? I’d have no issue putting it in front of a speaker. Maybe I need to get some GOM and compare


----------



## nathan_h

PixelPusher15 said:


> Did you see the testing for the HL Stretch Velvet? I’d have no issue putting it in front of a speaker. Maybe I need to get some GOM and compare


I would love to see the data. I may have seen it and forgotten. If it compares with the good choices from GOM and Acoustimac that would be great to know Since it could be very useful around a screen and into the room at least as far as the front wides.

Here is what I have in my notes about various GOM and Acoustimac fabrics. I don’t know what the Mel is. This is not my data. I know it was someone on AVS that measured them.

As you can see both GOM and Acoustimac make some fabric that one would not want to put in front of speakers, though for panels it would be manageable.


----------



## PixelPusher15

nathan_h said:


> I would love to see the data. I may have seen it and forgotten. If it compares with the good choices from GOM and Acoustimac that would be great to know Since it could be very useful around a screen and into the room at least as far as the front wides.
> 
> Here is what I have in my notes about various GOM and Acoustimac fabrics. I don’t know what the Mel is. This is not my data. I know it was someone on AVS that measured them.
> 
> As you can see both GOM and Acoustimac make some fabric that one would not want to put in front of speakers, though for panels it would be manageable.
> 
> View attachment 3337731


@CincyNick sneakily linked it above Acoustic Transparency of Royalty 3 Velvet, Stretch...


----------



## cricket9998

I got samples of dmd and gom. The dmd looked way nicer, felt softer, and seemed more transparent too. I made giant 8 foot tall panels with dmd black and they are almost invisible.


----------



## nathan_h

PixelPusher15 said:


> @CincyNick sneakily linked it above Acoustic Transparency of Royalty 3 Velvet, Stretch...
> 
> View attachment 3337769


Impressive. That stretch velvet looks good.


----------



## taylor101

CincyNick said:


> Has anyone tried the HL Velvet for acoustic panels that @PixelPusher15 tested in a thread a while back? I'm trying to get a good mix of "as black as possible" while also making sure I'm treating the room. Most of the stuff I've seen from GOM and other places looks dark gray in comparison.












Yep, much darker than spandex, like any velvet make sure you put in in the right angle. One side has sheen and one is flat









Spandex panels behind, on a black wall


----------



## woolfman

Does anyone have input if you can use R-8 Insulated Duct Wrap (roll form) to acoustically treat a screen wall?









Amazon.com: Master Flow 60 sq. ft. R-8 Insulated Duct Wrap : Industrial & Scientific


Buy Master Flow 60 sq. ft. R-8 Insulated Duct Wrap: Duct Tape - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



www.amazon.com


----------



## quattroman

Hi All, I decided to get serious about treating my media room.

I reached out to GIK for advice and they basically told me my $1,000 budget would not even cover the bass traps.

Feeling a bit deflated I started thinking about the situation and came up with this as a solution on the cheap
and I must say it works extremely well and has made me a true believer in room treatments.

It instantly tightened up and extended the bass, and what really surprised me was the increased clarity and soundstage on both my HT and the music system.

I did end up ordering some GIK panels within my budget and will post pix once I receive everything.


----------



## nathan_h

woolfman said:


> Does anyone have input if you can use R-8 Insulated Duct Wrap (roll form) to acoustically treat a screen wall?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Amazon.com: Master Flow 60 sq. ft. R-8 Insulated Duct Wrap : Industrial & Scientific
> 
> 
> Buy Master Flow 60 sq. ft. R-8 Insulated Duct Wrap: Duct Tape - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
> 
> 
> 
> www.amazon.com


Well, sort of. The issues I foresee are two fold: 

1. I can’t tell but the facing on the material may reflect high frequencies which is not ideal. You want to absorb high frequencies behind the screen. 
2. Hanging it may be tough and you’ll need to hangblack fabric over it.



quattroman said:


> Hi All, I decided to get serious about treating my media room.
> 
> I reached out to GIK for advice and they basically told me my $1,000 budget would not even cover the bass traps.
> 
> Feeling a bit deflated I started thinking about the situation and came up with this as a solution on the cheap
> and I must say it works extremely well and has made me a true believer in room treatments.
> 
> It instantly tightened up and extended the bass, and what really surprised me was the increased clarity and soundstage on both my HT and the music system.
> 
> I did end up ordering some GIK panels within my budget and will post pix once I receive everything.
> View attachment 3345221
> View attachment 3345222


That is an awesome solution. And it looks like it’s behind your head which is doubly useful.


----------



## anjunadeep

quattroman said:


> Hi All, I decided to get serious about treating my media room.
> 
> I reached out to GIK for advice and they basically told me my $1,000 budget would not even cover the bass traps.
> 
> Feeling a bit deflated I started thinking about the situation and came up with this as a solution on the cheap
> and I must say it works extremely well and has made me a true believer in room treatments.
> 
> It instantly tightened up and extended the bass, and what really surprised me was the increased clarity and soundstage on both my HT and the music system.
> 
> I did end up ordering some GIK panels within my budget and will post pix once I receive everything.
> View attachment 3345221
> View attachment 3345222


Looks fantastic. Nicely done. You built a frame or are using fabric track?


----------



## quattroman

anjunadeep said:


> Looks fantastic. Nicely done. You built a frame or are using fabric track?


It is Rockwool with an air gap behind which increases its effectiveness, and yes, I built a frame of 1x4 and wrapped it with acoustically transparent fabric from GIK.


----------



## Tom J. Davis

woolfman said:


> Does anyone have input if you can use R-8 Insulated Duct Wrap (roll form) to acoustically treat a screen wall?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Amazon.com: Master Flow 60 sq. ft. R-8 Insulated Duct Wrap : Industrial & Scientific
> 
> 
> Buy Master Flow 60 sq. ft. R-8 Insulated Duct Wrap: Duct Tape - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
> 
> 
> 
> www.amazon.com


I'm also trying to figure out how to treat my front wall without being able to find any of the JM products. My situation is also unique in that I can't do anything permanent, as the room needs to be able to go back to being a bedroom when we decide to sell in the next few years.


----------



## harrisu

Hi guys. I have used Rosco TV Black Paint all around my HT. I think its the next best thing after Black Velvet that comes closest to Black Velvet. Its a very think paint. Wanted to know if by any chance this paint absorbs high frequencies? 
Also, came here after a while. I see that there is a new Black Velvet that seems to be performing very well as an AT material. I have my panels covered with Stratch-Black Velvet but it seems like the from from Hobby Lobby has the best AT performance so far. Apologies but is this the correct one from HL ? 
Hobby Lobby Stretch Black Velvet


----------



## squared80

harrisu said:


> Hi guys. I have used Rosco TV Black Paint all around my HT. I think its the next best thing after Black Velvet that comes closest to Black Velvet. Its a very think paint. Wanted to know if by any chance this paint absorbs high frequencies?
> Also, came here after a while. I see that there is a new Black Velvet that seems to be performing very well as an AT material. I have my panels covered with Stratch-Black Velvet but it seems like the from from Hobby Lobby has the best AT performance so far. Apologies but is this the correct one from HL ?
> Hobby Lobby Stretch Black Velvet


Yes, that's it. Just wait for a coupon - they come out regularly in their print ads or if you subscribe to their emails. 40% off comes around every so often. When I got my coupon, not a single HL in all of Chicagoland had more than 6 yards of it. I called them all. But they will put in a special order for as many bolts as you want and they'll honor the coupon when you place the order.









Black Velvet Fabric | Hobby Lobby | 1427764


Get Black Velvet Fabric online or find other Black products from HobbyLobby.com




www.hobbylobby.com


----------



## anjunadeep

harrisu said:


> Hi guys. I have used Rosco TV Black Paint all around my HT. I think its the next best thing after Black Velvet that comes closest to Black Velvet. Its a very think paint. Wanted to know if by any chance this paint absorbs high frequencies?


I know what you mean, that stuff is more of a goop than a paint lol. I imagine the text does maybe have some very slight diffusion of ultra ultra ultra high frequencies, maybe, but I don't think it's anything we'd be able to hear or even really measure. 

Just FYI: Trouble with Rosco tv plaint is that's really designed for quickie roll ons for studio cycloramas and stuff and it's not very durable long term, so be careful around it if you care. Functionally it won't matter though. Great for behind screens and stuff.


----------



## mtbdudex

harrisu said:


> Hi guys. I have used Rosco TV Black Paint all around my HT. I think its the next best thing after Black Velvet that comes closest to Black Velvet. Its a very think paint. Wanted to know if by any chance this paint absorbs high frequencies?
> Also, came here after a while. I see that there is a new Black Velvet that seems to be performing very well as an AT material. I have my panels covered with Stratch-Black Velvet but it seems like the from from Hobby Lobby has the best AT performance so far. Apologies but is this the correct one from HL ?
> Hobby Lobby Stretch Black Velvet


Sound absorption per say is related to gas flow resistivity .. so no, paint does not absorb high frequencies 



Porous Absorber Calculator





















Sent from my iPhone 11Pro using Tapatalk


----------



## cricket9998

quattroman said:


> Hi All, I decided to get serious about treating my media room.
> 
> I reached out to GIK for advice and they basically told me my $1,000 budget would not even cover the bass traps.
> 
> Feeling a bit deflated I started thinking about the situation and came up with this as a solution on the cheap
> and I must say it works extremely well and has made me a true believer in room treatments.
> 
> It instantly tightened up and extended the bass, and what really surprised me was the increased clarity and soundstage on both my HT and the music system.
> 
> I did end up ordering some GIK panels within my budget and will post pix once I receive everything.
> View attachment 3345221
> View attachment 3345222


Nice. I like gik but they are really overpriced. I could build the same panel for 4x less if not more. I built 8x4 (that’s in feet) panels for the same price as one of their small monsters. And with better properties too. It’s 2” of oc703 and 3” of safe n sound with FSK tape for diffusion. I did get their alpha diffusers and larger monsters for the rear corners, but I saved literally thousands by doing 90% of the panels myself.


----------



## hokeyplyr48

Exactly my plans as well. Did you source the OC703 locally or have it shipped?


----------



## cricket9998

hokeyplyr48 said:


> Exactly my plans as well. Did you source the OC703 locally or have it shipped?


I got it from gik lmao. Cheapest I found for shipping. I called around a bunch of supply companies and no one has heard of it. Not sure why it’s so difficult to source. Safe n sound is easy to get but it’s not rigid which is why I used both. Rockwool rock board is equally difficult to source and not as good anyway.


----------



## nathan_h

I didn't realize GIK was so non competitive these days in terms of prices. Ten years ago, it was only slightly more expsnive to buy the completed panels versus paying to ship OC703 and buy the other pieces and do it oneself.

What I have learned since then is that the rigid fiberglass and rockwool insulation is always available from HVAC supply houses, because it is a critical part of just about every good HVAC installation -- but sometimes not the OC brand. But all the brands perform pretty much the same. So going with the OC is just a convenience thing, not a requirement.



The other "cheat" appears to be if you have a HOME DEPOT PRO (not regular) store in your area. They are not very common. For example, I think there is one in all of SF Bay Area. But if you have one, they carry this stuff, which works well in my experience (at about $60 a package).


*ROCKWOOL *R-6.3 Comfortboard 80 1-1/2 in. x 24 in. x 48 in. Stone Wool Insulated Sheathing Board (48 sqft)

I suppose if I could not find it locally because the supply houses wouldn't sell to someone without a contrctor license, I'd probably get the raw material kits from Acoustimac. They provide a kit which is kind of like an IKEA purchase (just bring your screw driver, or other basic tool, and assemble).


----------



## Dsauce281

FreMo said:


> Do you have pictures of these?


I made some panels for my friends home theater I'm building for him. I took pictures this time around.


----------



## squared80

Dsauce281 said:


> I made some panels for my friends home theater I'm building for him. I took pictures this time around.
> View attachment 3350603
> 
> View attachment 3350601
> 
> View attachment 3350604
> 
> 
> View attachment 3350602
> 
> View attachment 3350599
> 
> View attachment 3350598
> 
> View attachment 3350600


Those look very thin in the pictures. How deep are they going to be?


----------



## Dsauce281

squared80 said:


> Those look very thin in the pictures. How deep are they going to be?


3/4" mdf with a 2" border. The panels are small. Approx 22"x25"


----------



## squared80

Dsauce281 said:


> 3/4" mdf with a 2" border. The panels are small. Approx 22"x25"


Seems like a lot of work for minimal results. What material are you using for the interior?


----------



## Dsauce281

squared80 said:


> Seems like a lot of work for minimal results. What material are you using for the interior?


Not alot of work at all. The results are for aesthetic purposes. This is a very easy project requiring basic wood working skills. I finished them in under 2 hours. The only function they serve is to hide the two inwall subwoofers i built into the front stage. The black GOM material dissappears into the front stage against a matte black painted wall. The real work was building the subwoofer enclosures and installing them into the front wall. I had to move studs and build two platforms to support them behind the wall in the attic.


----------



## squared80

Dsauce281 said:


> The only function they serve is to hide the two inwall subwoofers i built into the front stage.


Ok. So they're not acoustic panels at all then. That makes more sense.


----------



## Dsauce281

squared80 said:


> Ok. So they're not acoustic panels at all then. That makes more sense.


No, they are not acoustic panels. Just simple panels to hide the front of the subs.

I will be building a full set of acoustic panels in the near future. I was quoted by GIK although they were high in price for my budget I think they are reasonable in price compared to other options. i want to save some $ so since I have the tools and skill I will be building my room's panels based on what they recommended. I will post pics when I start that project.


----------



## harrisu

mtbdudex said:


> Sound absorption per say is related to gas flow resistivity .. so no, paint does not absorb high frequencies
> 
> 
> 
> Porous Absorber Calculator
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone 11Pro using Tapatalk


ty ty. Very nice and informative post. Much appreciated.


----------



## Duc Vu

Hi. First time DIY acoustic panel builder here. I'm super inexperienced, so kindly help check if my plan below makes sense (Please note that I'm not from the US or any European countries so some recommendations in terms of brands/material on this forum may not apply to where I live)

**THE FRAME*: Instead of using wood, I use pvc boards. For me, those are easier to work with as I don't own any specialized tool to cut wood and I don't have to worry about wood dust. The boards are 1cm thick. They are a bit flimsy at longer length but I hope super glue and nails will hold them together just fine. The absorbing material won't be too heavy either so that helps.










This is the one frame I built so far:









**THE ABSORBING MATERIAL*: I looked for rockwool online and this was what I found. 5cm thick, 120cmx60cm per piece, 4 pieces per pack. I plan to use just 1 piece for each acoustic panel to save cost, meaning each panel will only be 5cm (~2") thick. Per my estimation, there will be 12 acoustic panels in my room in total, 9 on the walls and 3 on the ceiling. I hope those will suffice to reduce the current echo and absorb most of the problematic mid-high frequency reflections. As for the low end, the panel needs to be a lot thicker, but I don't have space in my room nor budget for that, so no bass trap at the moment.
*Question:* What density should I go for? Options are 40, 50, 60, and 80.









**THE FABRIC: *After doing some research, it seems to come down to 3 options: speaker cloth, burlap, and muslin. These are the ones I found in my area for each type:
-Speaker cloth:
This is the thinner, smoother and softer type that is used in old speakers' grills. It is harder to see through.








This is the thicker, more rigid with bigger air holes type that is used in modern speakers' grills. It is easier to see through, so could be problematic in pitch dark room when lights shine though the fabric and the rockwool inside is visible.








-Burlap: looks pretty rough and rigid, not sure if it is easy to wrap around the frame








-Muslin: looks soft enough









So which to choose?

Thanks in advance.


----------



## squared80

Duc Vu said:


> Hi. First time DIY acoustic panel builder here. I'm super inexperienced, so kindly help check if my plan below makes sense (Please note that I'm not from the US or any European countries so some recommendations in terms of brands/material on this forum may not apply to where I live)
> 
> **THE FRAME*: Instead of using wood, I use pvc boards. For me, those are easier to work with as I don't own any specialized tool to cut wood and I don't have to worry about wood dust. The boards are 1cm thick. They are a bit flimsy at longer length but I hope super glue and nails will hold them together just fine. The absorbing material won't be too heavy either so that helps.
> 
> View attachment 3353007
> 
> 
> This is the one frame I built so far:
> View attachment 3353008
> 
> 
> **THE ABSORBING MATERIAL*: I looked for rockwool online and this was what I found. 5cm thick, 120cmx60cm per piece, 4 pieces per pack. I plan to use just 1 piece for each acoustic panel to save cost, meaning each panel will only be 5cm (~2") thick. Per my estimation, there will be 12 acoustic panels in my room in total, 9 on the walls and 3 on the ceiling. I hope those will suffice to reduce the current echo and absorb most of the problematic mid-high frequency reflections. As for the low end, the panel needs to be a lot thicker, but I don't have space in my room nor budget for that, so no bass trap at the moment.
> *Question:* What density should I go for? Options are 40, 50, 60, and 80.
> View attachment 3353009
> 
> 
> **THE FABRIC: *After doing some research, it seems to come down to 3 options: speaker cloth, burlap, and muslin. These are the ones I found in my area for each type:
> -Speaker cloth:
> This is the thinner, smoother and softer type that is used in old speakers' grills. It is harder to see through.
> View attachment 3353011
> 
> This is the thicker, more rigid with bigger air holes type that is used in modern speakers' grills. It is easier to see through, so could be problematic in pitch dark room when lights shine though the fabric and the rockwool inside is visible.
> View attachment 3353017
> 
> -Burlap: looks pretty rough and rigid, not sure if it is easy to wrap around the frame
> View attachment 3353021
> 
> -Muslin: looks soft enough
> View attachment 3353030
> 
> 
> So which to choose?
> 
> Thanks in advance.


The answers lie within this very thread. Spend some time reading it. My personal suggestion is Hobby Lobby Black Velvet Fabric #1427764.








Black Velvet Fabric | Hobby Lobby | 1427764


Get Black Velvet Fabric online or find other Black products from HobbyLobby.com




www.hobbylobby.com


----------



## Rojolo

You should brace the center of the panel, PVC of those dimensions will flex when you fasten the fabric.


----------



## nathan_h

squared80 said:


> The answers lie within this very thread. Spend some time reading it. My personal suggestion is Hobby Lobby Black Velvet Fabric #1427764.
> 
> 
> 
> 
> 
> 
> 
> 
> Black Velvet Fabric | Hobby Lobby | 1427764
> 
> 
> Get Black Velvet Fabric online or find other Black products from HobbyLobby.com
> 
> 
> 
> 
> www.hobbylobby.com


Except they don't have Hobby Lobby in his country


----------



## nathan_h

Duc Vu said:


> *THE FRAME*: Instead of using wood, I use pvc boards. For me, those are easier to work with as I don't own any specialized tool to cut wood and I don't have to worry about wood dust. The boards are 1cm thick. They are a bit flimsy at longer length but I hope super glue and nails will hold them together just fine. The absorbing material won't be too heavy either so that helps.


You may find it necessary to make smaller panels so that the rigidity of the PVC is retained. I would try to make panels that can accommodate a half sheet of the Rockwool. So, approx 60cm x 60cm.



Duc Vu said:


> *THE ABSORBING MATERIAL*: I looked for rockwool online and this was what I found. 5cm thick, 120cmx60cm per piece, 4 pieces per pack. I plan to use just 1 piece for each acoustic panel to save cost, meaning each panel will only be 5cm (~2") thick. Per my estimation, there will be 12 acoustic panels in my room in total, 9 on the walls and 3 on the ceiling. I hope those will suffice to reduce the current echo and absorb most of the problematic mid-high frequency reflections. As for the low end, the panel needs to be a lot thicker, but I don't have space in my room nor budget for that, so no bass trap at the moment.
> *Question:* What density should I go for? Options are 40, 50, 60, and 80.


Frankly, all those densities are fine. I would get whichever is easiest and cheapest. If they are all the same, I would get the more dense one. 

Note that you don't have to use Rockwool. You might find some alternatives locally that are easier to source. Feel free to post questions about alternatives here and hopefully someone will have good answers. Take a look here: https://www.bobgolds.com/AbsorptionCoefficients.htm and you will see many alternatives. Just make sure it is BOTH good at absorbing AND rigid enough for you.

Regarding thickness. 5cm is okay. If you can use a "spacer" to make them sit off the wall with a 5cm air gap, THAT WOULD BE GREAT. That added depth without added material and weigh still helps you impact lower frequencies which is very useful for keeping the room from sounding imbalanced/too dry.



Duc Vu said:


> *THE FABRIC: *After doing some research, it seems to come down to 3 options: speaker cloth, burlap, and muslin. These are the ones I found in my area for each type:


All of these will work in terms of their audio performance. I would choose the one that you like the look of, that feels easiest to work with, maybe what fits the budget best, and perhaps which reflects the least amount of light. Not all black fabric is the same in this regard. You may also want to consider whether any are treated to resist fire. Personally, I greatly prefer such fabrics whenever possible.

And remember you can use super cheap fabric (probably the muslin?) on the back and then something that looks nicer (if you don't like the muslin look, for example) on the front, if that saves money or is easier to work with.


----------



## Duc Vu

nathan_h said:


> You may find it necessary to make smaller panels so that the rigidity of the PVC is retained. I would try to make panels that can accommodate a half sheet of the Rockwool. So, approx 60cm x 60cm.
> 
> 
> 
> Frankly, all those densities are fine. I would get whichever is easiest and cheapest. If they are all the same, I would get the more dense one.
> 
> Note that you don't have to use Rockwool. You might find some alternatives locally that are easier to source. Feel free to post questions about alternatives here and hopefully someone will have good answers. Take a look here: https://www.bobgolds.com/AbsorptionCoefficients.htm and you will see many alternatives. Just make sure it is BOTH good at absorbing AND rigid enough for you.
> 
> Regarding thickness. 5cm is okay. If you can use a "spacer" to make them sit off the wall with a 5cm air gap, THAT WOULD BE GREAT. That added depth without added material and weigh still helps you impact lower frequencies which is very useful for keeping the room from sounding imbalanced/too dry.
> 
> 
> 
> All of these will work in terms of their audio performance. I would choose the one that you like the look of, that feels easiest to work with, maybe what fits the budget best, and perhaps which reflects the least amount of light. Not all black fabric is the same in this regard. You may also want to consider whether any are treated to resist fire. Personally, I greatly prefer such fabrics whenever possible.
> 
> And remember you can use super cheap fabric (probably the muslin?) on the back and then something that looks nicer (if you don't like the muslin look, for example) on the front, if that saves money or is easier to work with.


Thanks for the reply.

I haven't properly tightened the pvc boards with screws yet so that may explain the flimsy feel. Hopefully the 120x60 frames will be rigid enough at the end as I don't want to divide them into 60x60 size - the workload will be more with smaller size.

As for density of the rockwool, 40 is around 25% cheaper than 80 here, so maybe I should opt for 40? But I thought denser means better absorbtion...

Yes there will be some air gap between the panel and the walls. You mention there's a chance the room may sound imbalanced/too dry with the panels installed? Currently in my room, there's almost nothing on the walls, and the ceiling is concrete. Most of the things in the room are hard surfaces. But although the clapping test shows that there's quite an amount of echo, the sound I get from the home theater system is still pretty good to my ears. I really don't want to risk after all this effort of building the panel, things sound worse than before.

Finally, I have the same thought of using muslin for the back, as it is the cheapest. For the front, I will probably go with speaker cloth - the non-seen-through type. Sacrifice a bit of breathability for less light reflection.


----------



## nathan_h

Duc Vu said:


> Thanks for the reply.
> 
> I haven't properly tightened the pvc boards with screws yet so that may explain the flimsy feel. Hopefully the 120x60 frames will be rigid enough at the end as I don't want to divide them into 60x60 size - the workload will be more with smaller size.


Thats your choice. Even with wood frames, I found 60x60 to work much better. Easier to handle. Easier to hang.



> As for density of the rockwool, 40 is around 25% cheaper than 80 here, so maybe I should opt for 40? But I thought denser means better absorbtion...


You are correct. More dense absorbs more. But the difference is tiny. Look at the numbers from the URL I posted in my last reply. Here is one section. You can see that the difference for a similar thickness but more dense rock wool product is frankly not worth paying more for.












> Yes there will be some air gap between the panel and the walls. You mention there's a chance the room may sound imbalanced/too dry with the panels installed? Currently in my room, there's almost nothing on the walls, and the ceiling is concrete. Most of the things in the room are hard surfaces. But although the clapping test shows that there's quite an amount of echo, the sound I get from the home theater system is still pretty good to my ears. I really don't want to risk after all this effort of building the panel, things sound worse than before.


It is unlikely to sound worse than having NO panels. But there are limits to what thin panels can do, and you can work around those limits by placing them off the wall with an air gap, where possible. 

If you know how to use the free REW software and have a measurement microphone, that is a great way to avoid creating problems and to understand what the room needs. It is not required. Based on what you describe, just getting some panels in there is a logical first step and likely to help things (especially when placed behind your head if there is a wall there).



> Finally, I have the same thought of using muslin for the back, as it is the cheapest. For the front, I will probably go with speaker cloth - the non-seen-through type. Sacrifice a bit of breathability for less light reflection.


No sacrifice. Other than cost


----------



## Duc Vu

nathan_h said:


> Thats your choice. Even with wood frames, I found 60x60 to work much better. Easier to handle. Easier to hang.
> 
> 
> 
> You are correct. More dense absorbs more. But the difference is tiny. Look at the numbers from the URL I posted in my last reply. Here is one section. You can see that the difference for a similar thickness but more dense rock wool product is frankly not worth paying more for.
> 
> View attachment 3353175
> 
> 
> 
> 
> It is unlikely to sound worse than having NO panels. But there are limits to what thin panels can do, and you can work around those limits by placing them off the wall with an air gap, where possible.
> 
> If you know how to use the free REW software and have a measurement microphone, that is a great way to avoid creating problems and to understand what the room needs. It is not required. Based on what you describe, just getting some panels in there is a logical first step and likely to help things (especially when placed behind your head if there is a wall there).
> 
> 
> 
> No sacrifice. Other than cost


I know how to use REW, but mainly to check the bass response and find the better placement for the subwoofer. What should I look at in REW to identify which problems I'm having with the mid and high frequency in my room and build/place the acoustic panels accordingly without creating more problems than solving the existing ones?

Behind me is a very big heavy wardrobe (left by previous house owner), so hanging the acoustic panels there is difficult unfortunately. I have been trying to get rid of it, but it is expensive so I will probably resell it. Just throwing it away seems like a big waste.

By sacrifice I mean comparing to the other type of speaker cloth, which has 2 layers and bigger air holes. The seller told me that type is more breathable, but more rigid and more expensive. I'm thinking of going for the 1 layer one, which is softer and smoother, smaller air holes so less see through, but also means less acoustically transparent.


----------



## nathan_h

Duc Vu said:


> I know how to use REW, but mainly to check the bass response and find the better placement for the subwoofer. What should I look at in REW to identify which problems I'm having with the mid and high frequency in my room and build/place the acoustic panels accordingly without creating more problems than solving the existing ones?


Unless you are covering 20% of the walls or more, I would not worry about the REW aspect any time soon. Just proceed.



> Behind me is a very big heavy wardrobe (left by previous house owner), so hanging the acoustic panels there is difficult unfortunately. I have been trying to get rid of it, but it is expensive so I will probably resell it. Just throwing it away seems like a big waste.


I agree. Best to find it a new home if possible. Then consider panels behind you.



> By sacrifice I mean comparing to the other type of speaker cloth, which has 2 layers and bigger air holes. The seller told me that type is more breathable, but more rigid and more expensive. I'm thinking of going for the 1 layer one, which is softer and smoother, smaller air holes so less see through, but also means less acoustically transparent.


Acoustic panels are not too picky. Any kind of speaker grill cloth is going to be fine in terms of the level of transparency.


----------



## Duc Vu

nathan_h said:


> Unless you are covering 20% of the walls or more, I would not worry about the REW aspect any time soon. Just proceed.
> 
> 
> 
> I agree. Best to find it a new home if possible. Then consider panels behind you.
> 
> 
> 
> Acoustic panels are not too picky. Any kind of speaker grill cloth is going to be fine in terms of the level of transparency.


All the panels combined definitely wont cover more than 20% of the walls. I can only build absorbers, not diffusers, so I think I need to strategically place those panels to avoid the room sounding too imbalanced like you said.

After doing some more research on reflection points and speaker boundary interference and reading the rockwool table you linked, my plan is now 2-inch panels on the side walls, ceilings and on the wardrobe behind me (I'll find a way to hang the panels on the wardrobe) to treat 1st & 2nd reflection points, and 4 inch panels behind each speakers to treat SBIR.


----------



## nathan_h

Duc Vu said:


> 4 inch panels behind each speakers to treat SBIR


Not a bad plan and I am sure you realize this from your reading but the speaker needs to be directly against the panel for this to work, otherwise the waves will be too long to be effectively trapped by a 4” panel. (That’s not a criticism, just a nuance that I personally didn’t understand for a while.)

—

About your broader plan: I anticipate you will get good results. If you can make them thicker or spaced off the wall in more of the planned locations, that will be an advantage, but is not required.

I should mention, for the sake of completeness, that SOME speakers don’t need the panels at the first reflection points. But this is very specific to certain rooms, certain layouts, and certain speakers. TLDR: The plan you have is the smart way to start and the most likely to work well.


----------



## Duc Vu

nathan_h said:


> Not a bad plan and I am sure you realize this from your reading but the speaker needs to be directly against the panel for this to work, otherwise the waves will be too long to be effectively trapped by a 4” panel. (That’s not a criticism, just a nuance that I personally didn’t understand for a while.)
> 
> —
> 
> About your broader plan: I anticipate you will get good results. If you can make them thicker or spaced off the wall in more of the planned locations, that will be an advantage, but is not required.
> 
> I should mention, for the sake of completeness, that SOME speakers don’t need the panels at the first reflection points. But this is very specific to certain rooms, certain layouts, and certain speakers. TLDR: The plan you have is the smart way to start and the most likely to work well.


Oh well I didn't know for sbir the speaker has to be up against the panel. In my case that won't work, at least for the fronts and center. I watched a few videos and they only said the thickness of the panel to treat sbir depends on how far the front baffle is from the wall behind. Anyway the thickest I can afford is 4inch panel, both space wise and budget wise. 

From research I also knew some speakers don't need first reflection treatment due to their good off axis performance. That said, my listening area is asymmetrical; the left side wall is closer to the MLP compared to the right side wall by quite an amount, so I figure having some absorbers on the left side wall will balance things out.


----------



## fattire

Duc Vu said:


> Oh well I didn't know for sbir the speaker has to be up against the panel. In my case that won't work, at least for the fronts and center. I watched a few videos and they only said the thickness of the panel to treat sbir depends on how far the front baffle is from the wall behind. Anyway the thickest I can afford is 4inch panel, both space wise and budget wise.


That is correct. The thickness of the panel depends on how far the front baffle is from the wall. The reason is that the distance from the wall dictates the frequency of the interference. A panel of a given thickness has a lower limit where it ceases to be effective. Below that limit, the panel isn't going to do anything but look pretty.

We can _raise_ the SBIR frequency by _reducing_ the distance of the speaker baffle and the wall causing the interference. Often times, we can get the speaker close enough for the panel to be 100% effective at fixing SBIR.


----------



## nathan_h

That is true. IIRC for a 4" panel to be effective, the baffle of a speaker must be pretty darn close to the wall, hence with most traditional speakers, the speaker would need to be against the panel for the baffle of the speaker to be close enough to a 4" panel for the 4" panel to be effective. 

So.....if @Duc Vu has small speakers and is a matter of inches from the the panel, it could work. If they are substantial speakers and say 30cm or 50cm from the wall, then it won't work.

I bet @fattire knows the math better than me, so it might be interesting to plug in the numbers for this case.

The other thing I didn't think about: a four inch panel that is spaced off the wall by four inches performs down as low as an 8" panel, it just doesn't attenuate as much (decibels) as a 8" panel would. So that might be an option here....

----

That being said, controlling SBIR, while useful, is two or three steps down the path, imo. The first step is to simply get six or ten panels up in the room. And that first step is going to be more impressive than all and any steps that follow, imo. That's not to say its not worth pursuing more acoustic treatment in the future. But this first batch are likely to be the biggest single improvement @Duc Vu will see in this room.


----------



## sdurani

Distance to the wall x 4 = wavelength of cancelled frequency. Very common to see a cancellation notch around 280Hz because people place bookshelf speakers against the front wall, putting the baffle about one foot away (x 4 = wavelength of 280Hz). If you have a big room, placing the speakers more than 3.5 from the front wall will drive the cancellation notch below an 80Hz crossover so that it is no longer a problem.


----------



## Duc Vu

nathan_h said:


> That is true. IIRC for a 4" panel to be effective, the baffle of a speaker must be pretty darn close to the wall, hence with most traditional speakers, the speaker would need to be against the panel for the baffle of the speaker to be close enough to a 4" panel for the 4" panel to be effective.
> 
> So.....if @Duc Vu has small speakers and is a matter of inches from the the panel, it could work. If they are substantial speakers and say 30cm or 50cm from the wall, then it won't work.
> 
> I bet @fattire knows the math better than me, so it might be interesting to plug in the numbers for this case.
> 
> The other thing I didn't think about: a four inch panel that is spaced off the wall by four inches performs down as low as an 8" panel, it just doesn't attenuate as much (decibels) as a 8" panel would. So that might be an option here....
> 
> ----
> 
> That being said, controlling SBIR, while useful, is two or three steps down the path, imo. The first step is to simply get six or ten panels up in the room. And that first step is going to be more impressive than all and any steps that follow, imo. That's not to say its not worth pursuing more acoustic treatment in the future. But this first batch are likely to be the biggest single improvement @Duc Vu will see in this room.


My front speakers are jbl stage a130. Bookshelf type. Please see the pic below for how far it is from the front wall. I thought they need to be some distance from the wall because the port is in the back. The center is jbl stage a125c so no port there.










The surround speakers are also jbl stage a130. They are quite close to the back wall.









If SBIR is not the focus at the moment, I should go for only 2 inch panels at the moment, and just put them at reflection points instead of behind speakers? Not sure where to put them on the front wall though if not behind speakers...

Pictures of my listening area/bedroom btw (sorry for the current mess):


----------



## Duc Vu

sdurani said:


> Distance to the wall x 4 = wavelength of cancelled frequency. Very common to see a cancellation notch around 280Hz because people place bookshelf speakers against the front wall, putting the baffle about one foot away (x 4 = wavelength of 280Hz). If you have a big room, placing the speakers more than 3.5 from the front wall will drive the cancellation notch below an 80Hz crossover so that it is no longer a problem.


My room is 15m2 and 3.5m high. My front speakers are jbl stage a130 (which has port in the back) and my center is jbl stage a125c (no port), around 45cm from the front wall. The surround speakers are also jbl stage a130. They are very close to the back wall, however.

Please check the post above for the fronts and surrounds' distance from the wall behind them, and pictures of my room. Thanks for the help.


----------



## nathan_h

Cool to see pictures. 

Yes, #1 thing is to sell that wardrobe/larger piece of furniture. You need all the space you can get behind your seating position for some distance and some 4" panels. (Or 2" panels spaced 2" off the wall.)* Personally, that would be my #1 concern in this room.

#2 It looks like side walls have windows and doors, making it tough to place panels on those walls. But if you can do so, that will likely be a good thing.

#3 Even though you might not solve SBIR with panels on the front wall, putting panels there (behind the speakers is okay but not required to place them there) will help with the overall sound in the room.

#4 But here is the big opportunity I didn't understand from your description but now I see in the photos. You have a very tall room! That's a HUGE opportunity. If this were my room, I would HANG panels from the ceiling on rope, wire, chain, thread that are 30cm below the ceiling. Even if they are just 2" panels. Persoanlly, I would cover 30 or 40% of the ceiling that way. It will help with overall "decay" time in the room. AND it will help with bass trapping by hanging them off the ceiling like that. This will be way more useful that worrying about SBIR.



























































-----



(*Again, on the back wall, six inches would be the perfect size, or 2" with a 4" air gap between panel and wall. But I realize that is not possible in your room).


----------



## fattire

_EDITED: Since nathan_h beat me to it ..._

I agree with nathan_h. I'd look to put panels in three areas to start. My priorities would be directly behind the MLP, then on the front wall behind the speakers (but likely favoring the inside to find that first reflection point), then the ceiling.


----------



## sdurani

Duc Vu said:


> Please check the post above for the fronts and surrounds' distance from the wall behind them, and pictures of my room.


Thanx for the pics; very helpful. Don't worry about the surrounds for the moment. Even in this day and age of surround sound, the front soundstage remains critical. That's where your attention will be focused, whether watching a movie or listening to music. As such, it helps to have clean & articulate sound up front, minimizing unwanted reflections that could muddy the soundstage and imaging.

To start, I would place a couple of small 200mm thick broadband absorbers on the front wall, just inward of the L & R speakers. While sitting in your main listening position, have someone move a hand mirror across the front wall to see if you can spot the reflections of your surround speakers. A couple of absorbers at those locations will help keep surround information in the surround field rather than coming at you from the same direction as the front soundstage.


----------



## NotShorty

Duc Vu said:


> My front speakers are jbl stage a130. Bookshelf type. Please see the pic below for how far it is from the front wall. I thought they need to be some distance from the wall because the port is in the back. The center is jbl stage a125c so no port there.
> View attachment 3353826
> 
> 
> 
> The surround speakers are also jbl stage a130. They are quite close to the back wall.
> View attachment 3353827
> 
> 
> If SBIR is not the focus at the moment, I should go for only 2 inch panels at the moment, and just put them at reflection points instead of behind speakers? Not sure where to put them on the front wall though if not behind speakers...
> 
> Pictures of my listening area/bedroom btw (sorry for the current mess):
> View attachment 3353828
> 
> View attachment 3353829


I hope you can preserve some of the aesthetic of the room. The dark brown wood plus black is a really nice combo.


----------



## Duc Vu

nathan_h said:


> Cool to see pictures.
> 
> Yes, #1 thing is to sell that wardrobe/larger piece of furniture. You need all the space you can get behind your seating position for some distance and some 4" panels. (Or 2" panels spaced 2" off the wall.)* Personally, that would be my #1 concern in this room.
> 
> #2 It looks like side walls have windows and doors, making it tough to place panels on those walls. But if you can do so, that will likely be a good thing.
> 
> #3 Even though you might not solve SBIR with panels on the front wall, putting panels there (behind the speakers is okay but not required to place them there) will help with the overall sound in the room.
> 
> #4 But here is the big opportunity I didn't understand from your description but now I see in the photos. You have a very tall room! That's a HUGE opportunity. If this were my room, I would HANG panels from the ceiling on rope, wire, chain, thread that are 30cm below the ceiling. Even if they are just 2" panels. Persoanlly, I would cover 30 or 40% of the ceiling that way. It will help with overall "decay" time in the room. AND it will help with bass trapping by hanging them off the ceiling like that. This will be way more useful that worrying about SBIR.
> 
> View attachment 3353857
> 
> 
> View attachment 3353858
> 
> 
> View attachment 3353859
> 
> 
> View attachment 3353860
> 
> 
> View attachment 3353861
> 
> 
> 
> View attachment 3353862
> 
> 
> 
> 
> 
> -----
> 
> 
> 
> (*Again, on the back wall, six inches would be the perfect size, or 2" with a 4" air gap between panel and wall. But I realize that is not possible in your room).


#1 Unfortunately it’s quite hard to sell such a huge thing. If there's any silver lining, maybe the wardrobe can act as a diffuser of some sort. Currently the MLP is 85cm away from that wardrobe, so there’s still some space behind me. I plan to hang two 2” panels onto the wardrobe, one on the left and one on the right of me. As for how to hang them, not sure yet.










#2 For the left-side wall, the doors to the balcony will be closed when the home theater is used. I will just find a way to hang the panels onto the doors. For the right-side wall, as mentioned, it is quite further away from MLP compared to the left-side wall, so maybe I won’t put any panels there. If anything, stuffs near the right wall may act as diffusers also.

#3 So should the panels behind the speakers still be 4” thick, or I can settle with just 2”?

#4 Previously there was a drop ceiling, so it didn't look that tall. But the bass in the room caused the drop ceiling to sometimes vibrate violently and created very annoying rattling sounds, so I had to remove it. Now it is just bare concrete ceiling, and that worsens the echo (but somehow the bass response becomes better than before, confirmed via REW). Yes, I will hang two 2” panels on the ceiling, most likely in between the top front in-ceiling atmos speakers (which also need to be hung now so I created DIY boxes for them)


----------



## Duc Vu

fattire said:


> _EDITED: Since nathan_h beat me to it ..._
> 
> I agree with nathan_h. I'd look to put panels in three areas to start. My priorities would be directly behind the MLP, then on the front wall behind the speakers (but likely favoring the inside to find that first reflection point), then the ceiling.


Sorry what do you mean by "favoring the inside to find that first reflection point"?


----------



## Duc Vu

sdurani said:


> Thanx for the pics; very helpful. Don't worry about the surrounds for the moment. Even in this day and age of surround sound, the front soundstage remains critical. That's where your attention will be focused, whether watching a movie or listening to music. As such, it helps to have clean & articulate sound up front, minimizing unwanted reflections that could muddy the soundstage and imaging.
> 
> To start, I would place a couple of small 200mm thick broadband absorbers on the front wall, just inward of the L & R speakers. While sitting in your main listening position, have someone move a hand mirror across the front wall to see if you can spot the reflections of your surround speakers. A couple of absorbers at those locations will help keep surround information in the surround field rather than coming at you from the same direction as the front soundstage.


200mm thick? 20cm? I don't think I can build such thick panels...

I use Fomex sheets instead of wood to build the panels' frame and these things are not very rigid from what I see. 20cm thick rockwool inside may break things apart. Maybe. And there's cost problem also.


----------



## Duc Vu

NotShorty said:


> I hope you can preserve some of the aesthetic of the room. The dark brown wood plus black is a really nice combo.


I actually want everything to be black


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## sdurani

Duc Vu said:


> 200mm thick?


Sorry, meant 100mm thick (4 inches).


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## Duc Vu

sdurani said:


> Sorry, meant 100mm thick (4 inches).


Nice. That I think I can manage.

Btw, what do you mean when you say "inward of L & R speakers"?


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## fattire

Duc Vu said:


> Sorry what do you mean by "favoring the inside to find that first reflection point"?





Duc Vu said:


> Btw, what do you mean when you say "inward of L & R speakers"?


Sit where you're going to watch / listen
Have a friend hold a mirror on the wall between the C and L speaker
Have the friend move the mirror until you can see the L speaker in it
Mark that spot with tape
That is where the center of the panel should go

Repeat this process ^^ on the other side for the R speaker


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## nathan_h

If you are not using that large wardrobe for storage, I would remove some of the doors on it, fill that with insulation, and then cover the opening (where the door used to be) with fabric. If you lived in a cold country I would say fill the wardrobe with coats and jackets, which will act as a bit of a bass trap. But you probably don't have a lot of jackets and coats!


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## Duc Vu

fattire said:


> Sit where you're going to watch / listen
> Have a friend hold a mirror on the wall between the C and L speaker
> Have the friend move the mirror until you can see the L speaker in it
> Mark that spot with tape
> That is where the center of the panel should go
> 
> Repeat this process ^^ on the other side for the R speaker


Maybe I misunderstood something but my setup is like this. The center is above the tv and the tv covers most of the space between the center and the right speaker. Where should the mirror go then?


----------



## fattire

Duc Vu said:


> Maybe I misunderstood something but my setup is like this. The center is above the tv and the tv covers most of the space between the center and the right speaker. Where should the mirror go then?
> View attachment 3353972


Pictures help. Thanks! If that's where you're sitting, then it appears (just eyeballing from the photo) that the first reflection point is either the TV or blocked by the TV. Treating that would likely not be possible. I have a large TV and they do present challenges like this.

Given the arrangement above, I think you are going to need to experiment a bit. I strongly suggest using 2-channel music with no upmixing. Play music you know well. Listen for a bit to create a baseline. Then put one panel behind the L&R speakers as close to the TV as you can get. Go back and listen to the _exact same passages of the exact same music_ and see what you hear. Is it better? Worse? Just different? You might need to do this a few times to see what's best.

I would also do the same experiment with the panels directly behind the MLP. Listen with no panels anywhere. Then put them directly behind the MLP and listen again for differences.


----------



## Duc Vu

fattire said:


> Pictures help. Thanks! If that's where you're sitting, then it appears (just eyeballing from the photo) that the first reflection point is either the TV or blocked by the TV. Treating that would likely not be possible. I have a large TV and they do present challenges like this.
> 
> Given the arrangement above, I think you are going to need to experiment a bit. I strongly suggest using 2-channel music with no upmixing. Play music you know well. Listen for a bit to create a baseline. Then put one panel behind the L&R speakers as close to the TV as you can get. Go back and listen to the _exact same passages of the exact same music_ and see what you hear. Is it better? Worse? Just different? You might need to do this a few times to see what's best.
> 
> I would also do the same experiment with the panels directly behind the MLP. Listen with no panels anywhere. Then put them directly behind the MLP and listen again for differences.


May I ask what first reflection point we are treating here? Reflection from the fronts or from the surrounds?


----------



## fattire

Duc Vu said:


> May I ask what first reflection point we are treating here? Reflection from the fronts or from the surrounds?


The fronts primarily, but it will also absorb reflections off the front wall from the surrounds.


----------



## Duc Vu

fattire said:


> The fronts primarily, but it will also absorb reflections off the front wall from the surrounds.


If it's for the fronts: I toed the fronts in a way that minimizes first reflection from the tv. But I wonder why absorbers on the front wall are for primarily treating the fronts' reflection. The fronts must be toed in very heavily for them to start causing first reflections off the front wall, no? It won't be a problem for most setup.

















If it's for the surrounds: yeah when I sit at MLP, I can see the surrounds inside the tv, which acts as a huge mirror. Meaning there's some sound bouncing off of the tv from the surrounds. You can see in the pic below; I put a small flash light on top of the right surround.


----------



## fattire

Because speakers are omni-directional up to 300 Hz or so. That sound is going out in a sphere from the speaker, hitting the wall and coming forward. SBIR doesn't occur just behind a speaker. It occurs _anywhere_ the reflection is 1/4 the wavelength of the frequency. That means that you can have SBIR off several boundary walls (depending on the room). This is especially true with speakers in/near corners.

Toe-in will potentially help the higher frequencies depending on the design of the speaker, but they aren't usually a problem because they are highly directional. Toe in might also completely screw up focus and envelopment. You should be positioning the speakers to create their best sound, then treating the problems that need attention from that positioning in the room. Everything is a compromise.

Testing as I outlined above i free, too. Build your panels and try them out. You'll surprise yourself.


----------



## anjunadeep

fattire said:


> Because speakers are omni-directional up to 300 Hz or so. That sound is going out in a sphere from the speaker, hitting the wall and coming forward. SBIR doesn't occur just behind a speaker. It occurs _anywhere_ the reflection is 1/4 the wavelength of the frequency. That means that you can have SBIR off several boundary walls (depending on the room). This is especially true with speakers in/near corners.
> 
> Toe-in will potentially help the higher frequencies depending on the design of the speaker, but they aren't usually a problem because they are highly directional. Toe in might also completely screw up focus and envelopment. You should be positioning the speakers to create their best sound, then treating the problems that need attention from that positioning in the room. Everything is a compromise.
> 
> Testing as I outlined above i free, too. Build your panels and try them out. You'll surprise yourself.


Would being IN the corner rather than near it actually help? Or rather, would the closer to the surface of the wall the driver is, the less thick the treatment would be needed to combat SBIR?


----------



## fattire

anjunadeep said:


> Would being IN the corner rather than near it actually help? Or rather, would the closer to the surface of the wall the driver is, the less thick the treatment would be needed to combat SBIR?


SBIR is all about distance to boundaries. The shorter the distance to the boundary causing the cancellation, the thinner the treatment we can get away with. The closer the boundary is to the speaker, the _stronger_ the SBIR effect can be (less distance attenuation), but again, still easier to treat.

SBIR can be cumulative as well. If I have a speaker equidistant from multiple boundaries, I can have _compound_ SBIR effects from multiple reflections causing cancellations at the same frequency. This is why this type of positioning is so heavily discouraged.


----------



## Duc Vu

fattire said:


> SBIR is all about distance to boundaries. The shorter the distance to the boundary causing the cancellation, the thinner the treatment we can get away with. The closer the boundary is to the speaker, the _stronger_ the SBIR effect can be (less distance attenuation), but again, still easier to treat.
> 
> SBIR can be cumulative as well. If I have a speaker equidistant from multiple boundaries, I can have _compound_ SBIR effects from multiple reflections causing cancellations at the same frequency. This is why this type of positioning is so heavily discouraged.


Can I ask you about something else? About the rockwool product.

In my country only ROCKWOOL brand is available. And within the ROCKWOOL brand only Cool n Comfort (used for roof) and Safe n Silent Pro (used for drywall/partition) are available.
















Below are the data sheets for each type. At 40kg/m3 (the density I go for), Cool n Comfort seems to have NRC of 1.0 and a detailed Sound absorption coefficient table, while Safe n Silent Pro has NRC of 0.9 and no such table, but mentions more about acoustic insulation performance. Which one should I choose?

Cool n Comfort data sheet

Safe n Silent data sheet


----------



## fattire

Duc Vu said:


> Can I ask you about something else? About the rockwool product.
> 
> In my country only ROCKWOOL brand is available. And within the ROCKWOOL brand only Cool n Comfort (used for roof) and Safe n Silent Pro (used for drywall/partition) are available.
> View attachment 3355900
> View attachment 3355895
> 
> 
> Below are the data sheets for each type. At 40kg/m3 (the density I go for), Cool n Comfort seems to have NRC of 1.0 and a detailed Sound absorption coefficient table, while Safe n Silent Pro has NRC of 0.9 and no such table, but mentions more about acoustic insulation performance. Which one should I choose?
> 
> Cool n Comfort data sheet
> 
> Safe n Silent data sheet


I don’t know enough in this specific area to make a recommendation. I’d defer to @nathan_h on this one for sure.


----------



## nathan_h

Duc Vu said:


> Can I ask you about something else? About the rockwool product.
> 
> In my country only ROCKWOOL brand is available. And within the ROCKWOOL brand only Cool n Comfort (used for roof) and Safe n Silent Pro (used for drywall/partition) are available.
> View attachment 3355900
> View attachment 3355895
> 
> 
> Below are the data sheets for each type. At 40kg/m3 (the density I go for), Cool n Comfort seems to have NRC of 1.0 and a detailed Sound absorption coefficient table, while Safe n Silent Pro has NRC of 0.9 and no such table, but mentions more about acoustic insulation performance. Which one should I choose?
> 
> Cool n Comfort data sheet
> 
> Safe n Silent data sheet


Technically it looks like cool and comfort is a little better, but if there is a big price difference I would choose whichever is cheapest (as long as the rigidity is the same). The difference is going to be very hard to measure and impossible to hear, in my experience.


----------



## Duc Vu

nathan_h said:


> Technically it looks like cool and comfort is a little better, but if there is a big price difference I would choose whichever is cheapest (as long as the rigidity is the same). The difference is going to be very hard to measure and impossible to hear, in my experience.


The price is roughly the same here so yeah...

Btw, do you think I should make holes on the sides of the frame that holds the rockwool, so more sound can pass through and be absorbed by the rockwool instead of being reflected by the hard surface of the frame?


----------



## nathan_h

Duc Vu said:


> The price is roughly the same here so yeah...
> 
> Btw, do you think I should make holes on the sides of the frame that holds the rockwool, so more sound can pass through and be absorbed by the rockwool instead of being reflected by the hard surface of the frame?


I suspect that due to the material you are using that you will want to retain the material without holes to be more rigid.

But I haven't used that material, so I am just guessing. 

There is a small benefit to open sides. 

In terms of the overall impact on the room, just adding one more panel to your room is likely to make more of a difference than cutting holes in the sides of the ones you are making. And be easier!


----------



## fattire

nathan_h said:


> I suspect that due to the material you are using that you will want to retain the material without holes to be more rigid.
> 
> But I haven't used that material, so I am just guessing.
> 
> There is a small benefit to open sides.
> 
> In terms of the overall impact on the room, just adding one more panel to your room is likely to make more of a difference than cutting holes in the sides of the ones you are making. And be easier!


Good points. Also, if it’s sold there like it is here, there will be way too much material for just 2 panels. I think there were 8 total bats in what I recently used on an interior wall. That was the smallest package of it I could purchase from my local hardware store.


----------



## Duc Vu

nathan_h said:


> I suspect that due to the material you are using that you will want to retain the material without holes to be more rigid.
> 
> But I haven't used that material, so I am just guessing.
> 
> There is a small benefit to open sides.
> 
> In terms of the overall impact on the room, just adding one more panel to your room is likely to make more of a difference than cutting holes in the sides of the ones you are making. And be easier!


I have decided to use wood instead of the pvc foam board I mentioned. I tried the pvc foam board to make one frame and it's honestly hard to work with due to its flimsy nature at longer length.


----------



## nathan_h

Yep. That makes sense. 

Personally I wouldn't both to cut openings in the sides. But that's because I'd rather just add an extra panel in the room. (I'm lazy.)


----------



## Duc Vu

nathan_h said:


> Yep. That makes sense.
> 
> Personally I wouldn't both to cut openings in the sides. But that's because I'd rather just add an extra panel in the room. (I'm lazy.)


If I want to make openings on the sides, I will probably won't cut big holes either. I will just drill multiple small holes.


----------



## Duc Vu

nathan_h said:


> Yep. That makes sense.
> 
> Personally I wouldn't both to cut openings in the sides. But that's because I'd rather just add an extra panel in the room. (I'm lazy.)


Which type of wood should I use for the panel? Pine wood or MDF?

I plan to build a thin frame using either pine wood or MDF, and then use a staple gun to attach plywood sheets to four sides of the frame to make a box for the rockwool to sit in, following this tutorial video:


----------



## fattire

Duc Vu said:


> Which type of wood should I use for the panel? Pine wood or MDF?
> 
> I plan to build a thin frame using either pine wood or MDF, and then use a staple gun to attach plywood sheets to four sides of the frame to make a box for the rockwool to sit in, following this tutorial video:


I’d use pine. Weighs less and doesn’t create a ton of dust when working with it like MDF does. Probably a concern for you given what you previously mentioned.


----------



## nathan_h

Agree. Pine is typically better in my opinion (for the reasons @fattire states) and involves less cutting.

I'm going to experiment with using plywood, but haven't yet so I cannot comment on that. The advantage of MDF or plywood and other manufactured materials is that is it very flat/square and less likely to to expand and contract, in my experience. (I also have a theory that I might be able to use less bulky material, eg, 1/2" or 12mm plywood, instead of 3/4" [called 1"] pine boards, but I have NOT tested that idea yet.)


----------



## NotShorty

Duc Vu said:


> Which type of wood should I use for the panel? Pine wood or MDF?
> 
> I plan to build a thin frame using either pine wood or MDF, and then use a staple gun to attach plywood sheets to four sides of the frame to make a box for the rockwool to sit in, following this tutorial video:


Pretty good video, but I would consider french cleats rather than picture wire because IMO it'd be easier to ensure that all your panels are the exact same height.


----------



## fattire

nathan_h said:


> Agree. Pine is typically better in my opinion (for the reasons @fattire states) and involves less cutting.
> 
> I'm going to experiment with using plywood, but haven't yet so I cannot comment on that. The advantage of MDF or plywood and other manufactured materials is that is it very flat/square and less likely to to expand and contract, in my experience. (I also have a theory that I might be able to use less bulky material, eg, 1/2" or 12mm plywood, instead of 3/4" [called 1"] pine boards, but I have NOT tested that idea yet.)


I'll be using 3/4" BB ply to build my DIY screen frame when the time comes for the reasons you mention. There's certainly more cutting involved, but worth it when long-term stability is a primary requirement.


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## hokeyplyr48

fattire said:


> I'll be using 3/4" BB ply to build my DIY screen frame when the time comes for the reasons you mention. There's certainly more cutting involved, but worth it when long-term stability is a primary requirement.


I did 1/2” for mine and it was more than sturdy enough. I would not do 3/4” otherwise it’ll be stupid heavy and cost more. The strength comes from the vertical braces and the boards running perpendicular on the back.


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## fattire

hokeyplyr48 said:


> I did 1/2” for mine and it was more than sturdy enough. I would not do 3/4” otherwise it’ll be stupid heavy and cost more. The strength comes from the vertical braces and the boards running perpendicular on the back.


I'll be doing what you tell me to do ;-)


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## 3fingerbrown

Hey guys I'm going to do fabricmate wall covering system on my theater walls. It will cover all the areas between the columns, but I also have areas where it won't cover because of a kitchen area, screen, big sliding doors, etc. My current plan would be to treat 50% of the walls. About 2/3 of the floor of the room is carpet but the back 1/3 is hard surface. No treatments on the ceiling. You can see some pictures in this link:









The Big Daddy Theater


This is looking killer.




www.avsforum.com





My question is do you think 50% wall coverage is good?

Should I do one inch treatments or half-inch treatments?

I really don't have the expertise or interest in doing an acoustic analysis of the room, and I'm really just looking to soften things up. The room is too harsh right now to my uneducated ears.

Thanks


----------



## Duc Vu

fattire said:


> I’d use pine. Weighs less and doesn’t create a ton of dust when working with it like MDF does. Probably a concern for you given what you previously mentioned.


I actually will ask the seller to cut the wood to my desired sizes and assemble the main frame for me so yeah no need to worry about dust. I will just use a staple gun to attach the sides to the frame. So should I use MDF for both the frame and the sides? Or pinewood for the frame and MDF for the sides?


----------



## fattire

Duc Vu said:


> I actually will ask the seller to cut the wood to my desired sizes and assemble the main frame for me so yeah no need to worry about dust. I will just use a staple gun to attach the sides to the frame. So should I use MDF for both the frame and the sides? Or pinewood for the frame and MDF for the sides?


I'd still use pine as staples are a pain in the rear with MDF due to the density. Pine will still be lighter in weight as well.


----------



## 3fingerbrown

Can anyone help me out my questions above?

Is 50% wall coverage a good percentage or too much?

Should I do one inch treatments or half-inch treatments?

Is treating the screen wall a must? I can't do behind the screen but I could do right and left side of the screen. 

I don't have time to read 683 pages of acoustic treatment discussion, so any input is appreciated!


----------



## Duc Vu

fattire said:


> I'd still use pine as staples are a pain in the rear with MDF due to the density. Pine will still be lighter in weight as well.


So pine for the frame and mdf for the sides?


----------



## hokeyplyr48

No, he’s saying pine all around. It’s a pain to cut, makes a ton of dust, and is super heavy. Use pine and it’ll be fine


----------



## fattire

Duc Vu said:


> So pine for the frame and mdf for the sides?


What @hokeyplyr48 said. Pine for everything.


----------



## Duc Vu

hokeyplyr48 said:


> No, he’s saying pine all around. It’s a pain to cut, makes a ton of dust, and is super heavy. Use pine and it’ll be fine


@fattire In the video I link, the mdf used for the sides were just 2-3mm thick and the guy used a staple gun to attach them to the main pine frame. That will be ok in term of weight I guess?


----------



## fattire

Duc Vu said:


> @fattire In the video I link, the mdf used for the sides were just 2-3mm thick and the guy used a staple gun to attach them to the main pine frame. That will be ok in term of weight I guess?
> 
> View attachment 3357587


Probably fine. Your panels. Your call 😊


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## Duc Vu

fattire said:


> Probably fine. Your panels. Your call 😊


Well I'm a novice so I have no idea. That's why I'm asking for opinions from experts here


----------



## flyers10

I'd just use 1x4 pine.


----------



## Duc Vu

So I got a sample of 1-layer speaker cloth (right) and 2-layer muslin (left). Using the breath test, it seems speaker cloth is a bit more breathable. Neither allows as much air pass through as I expected though. Speaker cloth has a more shiny texture to it (kinda like velvet) so that may be a problem when watching in a pitch dark room that requires non-reflective surfaces, but it is less prone to creases than muslin.


----------



## squared80

Duc Vu said:


> Well I'm a novice so I have no idea. That's why I'm asking for opinions from experts here


You keep asking the same question and we keep telling you the same thing. Use pine. It's easier, especially for a novice. But in the end, do what you want. It's your build.


----------



## hokeyplyr48

This. MDF provides no value here. Wrapping pine with MDF accomplishes nothing. Just use pine, it is all you need.


----------



## nathan_h

3fingerbrown said:


> Hey guys I'm going to do fabricmate wall covering system on my theater walls. It will cover all the areas between the columns, but I also have areas where it won't cover because of a kitchen area, screen, big sliding doors, etc. My current plan would be to treat 50% of the walls. About 2/3 of the floor of the room is carpet but the back 1/3 is hard surface. No treatments on the ceiling. You can see some pictures in this link:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The Big Daddy Theater
> 
> 
> This is looking killer.
> 
> 
> 
> 
> www.avsforum.com
> 
> 
> 
> 
> 
> My question is do you think 50% wall coverage is good?
> 
> Should I do one inch treatments or half-inch treatments?
> 
> I really don't have the expertise or interest in doing an acoustic analysis of the room, and I'm really just looking to soften things up. The room is too harsh right now to my uneducated ears.
> 
> Thanks


That's a real nice room. Bravo.

You are conflating fabric covering the wall (neutral sound impact) with acoustic treatment BEHIND the fabric (substantial impact to the sound).

So, two parts to the answer:

1) Cover as much of the room as you like with acoustically transparent fabric. It is about the LOOK.

2) For acoustic panels, I would stick with a minimum of 3" thick and ideally go for 4". If you make them less thick they will act like a tone control, reducing the treble and not giving you consistent sound. If you must go with a smaller profile, two inch thick panels with an air gap behind them can work, as well.

This room looks pretty live. I would put at least one 2'x4' panel between each column, including the front and back wall in addition to the side walls.

(Actually, I would probably put a bit more than that, and I would definitely use thicker panels, esepcally on the back wall. And I would put some panels on the ceiling. And I might throw in some diffusion. But from your post I think you want to keep it simple, hence my answer.)

--

UPDATE: I see you have an interesting rear wall. Not sure how to treat that if you are able to close it. If not, don't worry about it.

Otherwise, here are the places I would place panels in this room. By my quick back of the napkin calculation, this would be about 10% coverage. I know it looks like a lot of panels but you compare that with all the other untreated spaces (most of the floor and carpet only halfway counts, all of the rear wall, most of the front wall, much of the ceiling) and it is very modest in terms of coverage.


----------



## Duc Vu

hokeyplyr48 said:


> This. MDF provides no value here. Wrapping pine with MDF accomplishes nothing. Just use pine, it is all you need.





squared80 said:


> You keep asking the same question and we keep telling you the same thing. Use pine. It's easier, especially for a novice. But in the end, do what you want. It's your build.


How do you deal with the pine wood being not completely straight when you have to staple the sides onto each side of the frame like in the video? I asked a local seller to cut pinewood to my desire sizes and they said there would be +/- 2 to 3mm error and each piece of wood might not be 100% straight (curves at some places) due to it being natural wood.


----------



## squared80

Duc Vu said:


> How do you deal with the pine wood being not completely straight when you have to staple the sides onto each side of the frame like in the video? I asked a local seller to cut pinewood to my desire sizes and they said there would be +/- 2 to 3mm error and each piece of wood might not be 100% straight (curves at some places) due to it being natural wood.


They don't need to be perfect, and you won't even be able to tell if you're talking about 2-3mm. You can also use cross-braces in the middle to avoid some warping, and just sand down any connection points that aren't perfectly aligned.


----------



## 3fingerbrown

nathan_h said:


> That's a real nice room. Bravo.
> 
> You are conflating fabric covering the wall (neutral sound impact) with acoustic treatment BEHIND the fabric (substantial impact to the sound).
> 
> So, two parts to the answer:
> 
> 1) Cover as much of the room as you like with acoustically transparent fabric. It is about the LOOK.
> 
> 2) For acoustic panels, I would stick with a minimum of 3" thick and ideally go for 4". If you make them less thick they will act like a tone control, reducing the treble and not giving you consistent sound. If you must go with a smaller profile, two inch thick panels with an air gap behind them can work, as well.
> 
> This room looks pretty live. I would put at least one 2'x4' panel between each column, including the front and back wall in addition to the side walls.
> 
> (Actually, I would probably put a bit more than that, and I would definitely use thicker panels, esepcally on the back wall. And I would put some panels on the ceiling. And I might throw in some diffusion. But from your post I think you want to keep it simple, hence my answer.)
> 
> --
> 
> UPDATE: I see you have an interesting rear wall. Not sure how to treat that if you are able to close it. If not, don't worry about it.
> 
> Otherwise, here are the places I would place panels in this room. By my quick back of the napkin calculation, this would be about 10% coverage. I know it looks like a lot of panels but you compare that with all the other untreated spaces (most of the floor and carpet only halfway counts, all of the rear wall, most of the front wall, much of the ceiling) and it is very modest in terms of coverage.
> 
> 
> 
> View attachment 3357730



Thanks for the advice! The fabricmate system is designed to be custom installed using track in whatever design you want. My baseboard below was cut to protrude out 1 inch below, so I was planning on covering the entire wall from column to column with one inch thick treatments. That would mean about 40%-45% of the vertical walls, but nothing on the ceiling and also quite a few hard surfaces like the wood floor in the rear (about 1/3 of the room) etc. If it is too much absorption, I could subtract before I put up the fabric, but I like the wall-to-wall look that the fabricmate system provides, versus doing framed panels. I don't have a picture of the rear sliding door, it is a hard wood door. 

If I went with a thicker 2 or 3 inch panel, I probably wouldn't go with the column-to-column look, but do framed panels. But I don't know how much the extra inch of absorption gets me in terms of sound quality.


----------



## nathan_h

3fingerbrown said:


> But I don't know how much the extra inch of absorption gets me in terms of sound quality.


A three inch panel does twice as much work in the crossover region versus the one inch panel, and is more consistent throughout the audio range. That means it is neutral rather than acting like someone turned down the treble control.



http://www.bobgolds.com/AbsorptionCoefficients.htm


----------



## Dan Hitchman

3fingerbrown said:


> Can anyone help me out my questions above?
> 
> Is 50% wall coverage a good percentage or too much?
> 
> Should I do one inch treatments or half-inch treatments?
> 
> Is treating the screen wall a must? I can't do behind the screen but I could do right and left side of the screen.
> 
> I don't have time to read 683 pages of acoustic treatment discussion, so any input is appreciated!


On average, you want about 15% total absorption coverage throughout the room (that includes absorption cloud panels on the ceiling at the first reflection points for the front three speakers) with 15-20% diffusion coverage. It depends on the room. If you go over that, you can actually start making the room sound worse, not better. That's based on the total footage of the room (Length, Width, and Height). About the first half of the room use 2D diffusion panels, back half of the room, use 3D diffusion.

Anthony Grimani recommends not mirroring panels. Instead of an absorption panel on each side of the wall mirroring each other, alternate your diffusion and absorption.

Two inch absorption treatments is the minimum thickness. If the panel is open in the back (no solid wood panel, but just transparent fabric) you can use stand off's to create an air gap, which can add extra benefits without paying more for thicker panels. Half or one inch treatments won't do much good at all.

In a false screen wall with acoustic screen scenario, you normally would use a sandwich of 1" thick Linacoustic (or similar treated, semi-ridged sound duct fabric), 3-6 ply poly sheeting, and 1" thick Linacoustic on the walls and ceiling.


----------



## squared80

Dan Hitchman said:


> On average, you want about 15% total absorption coverage throughout the room (that includes absorption cloud panels on the ceiling at the first reflection points for the front three speakers) with 15-20% diffusion coverage. It depends on the room. If you go over that, you can actually start making the room sound worse, not better. That's based on the total footage of the room (Length, Width, and Height). About the first half of the room use 2D diffusion panels, back half of the room, use 3D diffusion.
> 
> Anthony Grimani recommends not mirroring panels. Instead of an absorption panel on each side of the wall mirroring each other, alternate your diffusion and absorption.
> 
> Two inch absorption treatments is the minimum thickness. If the panel is open in the back (no solid wood panel, but just transparent fabric) you can use stand off's to create an air gap, which can add extra benefits without paying more for thicker panels. Half or one inch treatments won't do much good at all.
> 
> In a false screen wall with acoustic screen scenario, you normally would use a sandwich of 1" thick Linacoustic (or similar treated, semi-ridged sound duct fabric), 3-6 ply poly sheeting, and 1" thick Linacoustic on the walls and ceiling.


Good advice here. +1 all around. Because I had extra material, my front stage is a little different. Behind the screen, my walls and ceiling have a 2" air gap, 2" of Rockwool 60, then 3.5" of pink fluffy.


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## 3fingerbrown

Okay so for the percentage of room coverage for acoustic panels, which is recommended at 15-20%, this includes the ceilings, walls, floor, etc. My room is 29 feet length, 24 feet width, 8.3 feet height. So if I go back to my math and calculate the surface area of a cuboid, my formula produces 2,272 square feet for my theater. This is the total square feet of the floor, walls, and ceiling. 

Now 450 square feet of acoustic panels as the numerator would be about 19% of coverage for this theater with 2,272 as the denominator. But that includes the floor, which is mostly carpet, so that is 282 square feet of carpet already there. Do I subtract that carpet out of the equation? 450-282= 168. Which means I need only about 168 square feet of panels? That seems very low. Am I off track? 168 square feet would mean about 5.25 panels of a 4x8 foot size. Is that right?


----------



## Dan Hitchman

3fingerbrown said:


> Okay so for the percentage of room coverage for acoustic panels, which is recommended at 15-20%, this includes the ceilings, walls, floor, etc. My room is 29 feet length, 24 feet width, 8.3 feet height. So if I go back to my math and calculate the surface area of a cuboid, my formula produces 2,272 square feet for my theater. This is the total square feet of the floor, walls, and ceiling.
> 
> Now 450 square feet of acoustic panels as the numerator would be about 19% of coverage for this theater with 2,272 as the denominator. But that includes the floor, which is mostly carpet, so that is 282 square feet of carpet already there. Do I subtract that carpet out of the equation? 450-282= 168. Which means I need only about 168 square feet of panels? That seems very low. Am I off track? 168 square feet would mean about 5.25 panels of a 4x8 foot size. Is that right?


Remember, it's 15% for absorption panels and 15-20% for diffusion panels (a mix of 2D and 3D). so 30-35% of the surface area (walls and ceiling) would be acoustic panels.


----------



## nathan_h

3fingerbrown said:


> Okay so for the percentage of room coverage for acoustic panels, which is recommended at 15-20%, this includes the ceilings, walls, floor, etc. My room is 29 feet length, 24 feet width, 8.3 feet height. So if I go back to my math and calculate the surface area of a cuboid, my formula produces 2,272 square feet for my theater. This is the total square feet of the floor, walls, and ceiling.
> 
> Now 450 square feet of acoustic panels as the numerator would be about 19% of coverage for this theater with 2,272 as the denominator. But that includes the floor, which is mostly carpet, so that is 282 square feet of carpet already there. Do I subtract that carpet out of the equation? 450-282= 168. Which means I need only about 168 square feet of panels? That seems very low. Am I off track? 168 square feet would mean about 5.25 panels of a 4x8 foot size. Is that right?


Contrary to popular mythology, carpet is a poor absorber, attacking just the high treble. So it mostly doesn't count when you get to this level of scientific analysis.

Heck, even the 15 to 20 % absorption is a ballpark. Professionals will measure the actual decay times (RT60) and add or subtract based on the actual results in the room.

In your room, 400 sq feet of panels would be fifty of the standard 2'x4' panels. I'll bet you can't get close to that many in there in a way that you find acceptable? 

Note, too, that you do NOT want the panels all together. You want them roughly evenly distributed round the room. But since your room has areas that cannot accommodate panels at all, you will probably be limited by placement options and maybe only have room for 20 or 30 panels.... which, Ill bet once you measure it, will probably be doing you a world of good.

---

Another way to think of it, I would not want to fill more than half the space between any of those columns with panels/fiberglass, and the other half of the space would ideally be some kinds of diffusion like Dan alludes to. So your effective upper limit on how much coverage may be lower than the traditional target. But that's probably okay. The size of your room is helping you, too.


----------



## sukumar

I am putting a screen over the windows. Unfortunately, 150-inch screen will not cover 7 inches on each side of the screen as windows are exposed. I am wondering what acoustics can be placed partly on wall and window to cover not to have a distraction and helps acoustics. .Appreciate to share


----------



## nathan_h

sukumar said:


> I am putting a screen over the windows. Unfortunately, 150-inch screen will not cover 7 inches on each side of the screen as windows are exposed. I am wondering what acoustics can be placed partly on wall and window to cover not to have a distraction and helps acoustics. .Appreciate to share


7 inches wide won't really make a difference for acoustics. Just hang some black velvet that is thick enough to block the light.

Now, if you could fill the window well (the whole thing) with acoustic panels made from fiberglass or rock wool insulation of six or more inches in DEPTH, that would act like a nice bass trap behind the screen.....


----------



## erics3000

So I wanted to start treating my room with a diy wood diffuser first on the back wall. Next year I will be finished and ready to do some upgrades but figure diy acoustic are easy and cheap. I have all the tools so this will keep busy while waiting for parts on my other project.

DIY Sound Diffusers: Great Method to Make Skyline Diffusers! - Mixing Tips
I would like it some where around 6x2 feet between my to rear surrounds. I found this calculator and was wondering what frequencies is should use for my theater back wall? Later I will work on some absorption in my front room but nor sure if I am going to change things around yet, so I figure this will be a nice project this winter and a good start. Good thing is I like the look of them so I am going to give it a shot. I also plan on some diy absorption panels too.






Calculate Skyline Diffusor with given frequencies







www.mh-audio.nl





My room is currently 7.2.2 Room is 13x18 9 ft ceilings. Was an existing media room when I moved in. Some of my issues are a door on each side in from of room. Three 38in wide windows on the right side with about 3 in gap between the windows. One of my side speakers barely fits between the windows. 115 screen and I sit about 9 feet from screen. 11ft in the room depth starts a one foot riser for the back row. So I have been trying to figure where I should put some absorption panels maybe over windows. Curious with any ideas? I wanted to go with a transparent screen, but want to hold off before I do any big construction. I really do want get a mini DSP but need to do a lot of research first. I like how with mini DSP let you tune multiple subs. Subs will definitely be done the road. Thinking to start with two Marty 18s and then grow to 4 or just suck it. I am Still trying to learn a good way to tune. I have a Onkyo TXRZ 830 and used the default software but want to do learn how to level up. So I figure I will try to improve room acoustics while figuring which way I am goin on speakers down the road. Any advice is appreciated.


----------



## erics3000

I am planning on removing the movie shelf and hopefully paint all the white trim black and maybe the front wall, this winter.


----------



## Dan Hitchman

erics3000 said:


> I am planning on removing the movie shelf and hopefully paint all the white trim black and maybe the front wall, this winter.
> 
> 
> View attachment 3369012
> 
> View attachment 3369011


I would paint the frontal sidewalls up to your door flat black. You want to kill the side reflections off the screen as well. Even better? Black velvet instead of black paint. A floating screen looks fantastic.


----------



## squared80

I'm amazed how much pre-made skyline diffusors cost, even made from EPS. Maybe I should create my own online store for affordable versions. What a racket. I'm making my own, anyway, but for future reference, does anyone know of any cheap EPS options out there?


----------



## nathan_h

erics3000 said:


> I am planning on removing the movie shelf and hopefully paint all the white trim black and maybe the front wall, this winter.
> 
> 
> View attachment 3369012
> 
> View attachment 3369011





erics3000 said:


> So I wanted to start treating my room with a diy wood diffuser first on the back wall. Next year I will be finished and ready to do some upgrades but figure diy acoustic are easy and cheap. I have all the tools so this will keep busy while waiting for parts on my other project.
> 
> DIY Sound Diffusers: Great Method to Make Skyline Diffusers! - Mixing Tips
> I would like it some where around 6x2 feet between my to rear surrounds. I found this calculator and was wondering what frequencies is should use for my theater back wall? Later I will work on some absorption in my front room but nor sure if I am going to change things around yet, so I figure this will be a nice project this winter and a good start. Good thing is I like the look of them so I am going to give it a shot. I also plan on some diy absorption panels too.
> 
> 
> 
> 
> 
> 
> Calculate Skyline Diffusor with given frequencies
> 
> 
> 
> 
> 
> 
> 
> www.mh-audio.nl
> 
> 
> 
> 
> 
> My room is currently 7.2.2 Room is 13x18 9 ft ceilings. Was an existing media room when I moved in. Some of my issues are a door on each side in from of room. Three 38in wide windows on the right side with about 3 in gap between the windows. One of my side speakers barely fits between the windows. 115 screen and I sit about 9 feet from screen. 11ft in the room depth starts a one foot riser for the back row. So I have been trying to figure where I should put some absorption panels maybe over windows. Curious with any ideas? I wanted to go with a transparent screen, but want to hold off before I do any big construction. I really do want get a mini DSP but need to do a lot of research first. I like how with mini DSP let you tune multiple subs. Subs will definitely be done the road. Thinking to start with two Marty 18s and then grow to 4 or just suck it. I am Still trying to learn a good way to tune. I have a Onkyo TXRZ 830 and used the default software but want to do learn how to level up. So I figure I will try to improve room acoustics while figuring which way I am goin on speakers down the road. Any advice is appreciated.


This is going to be a great room.

Two subs positioned well and set up properly will likely be more than enough to wake the neighbors in this size room. And yes, it is possible a minidsp will be useful in setting them up. But before assuming you need one, learning to measure with REW will be important to indicate whether you do and what settings to use.

This thread however is about acoustic treatment. 

In a room this size with a row so close to the back wall, using primarily thick (at least four inches and six is better) absorption in the back wall behind the seats will likely be more more useful than diffusion there. 

The most likely effective approach to side wall treatment will be some four inch thick panels like the 2x4x4 panels from GIK, probably two or three on each side wall. This is a middle of the road approach since you don’t know what speakers you will have in the future and you don’t have a way to measure audio in the room yet.

If you still have budget after picking up six or ten acoustic absorption panels, then some diffusion between those may be useful but I’d focus on other more important aspects like the speakers, subs, paint, and learning REW first.


----------



## erics3000

Thanks for the info researching REW now and will start on some diy absorption and diffusion panels. I am starting lie the jar clones, thanks


----------



## WTS

nathan_h said:


> 7 inches wide won't really make a difference for acoustics. Just hang some black velvet that is thick enough to block the light.
> 
> Now, if you could fill the window well (the whole thing) with acoustic panels made from fiberglass or rock wool insulation of six or more inches in DEPTH, that would act like a nice bass trap behind the screen.....


Hi Nathan,
So you're saying it's okay to fill the wall behind the screen with absorption-rockwool, like you just told sukumar (is this good for 2 chan systems as well), but the side walls and back should have the panels spaced apart? My area behind my screen and between my speakers is about 8'x8'. I was thinking of doing it anyway with 3" or 5.5" safe n sound roxul, but someone mentioned even the front wall should be spaced. So which is it fill it all or space it on the front wall? Thanks

Also are people saying that carpet between you and the speakers does nothing for the sound, or any reflections from the screen. I have hardwood floors(satin finish) and I would have thought putting "some" carpet would help out even if a little.


----------



## nathan_h

Opinions differ. But the theory about insulation filling the whole area behind the screen is to do three things:

1. Prevent comb filtering from high frequencies bouncing back off the screen. Even two inches of material can solve this.

2. Prevent SBIR. This can take six or more inches of depth depending on how far the speaker front is from the wall.

3. Trap bass. This benefits from a foot or two feet of depth.

It is possible to run into trouble with too much insulation absorption panels around the room making it too dead. Hence the recommendation to space them around the room. I’m less worried about the front wall in this regard but to be safe you can measure the room with REW to see how love or dead it is.

—-

Some carpet is okay. It’s too thin to do much more than tame some high frequencies so it’s not a great solution overall. But I too would put a thick area rug with padding on the hard floor between me and my front speakers.


----------



## sukumar

I am considering cotton for acoustic panels. How do you compare it with polyester or foam? Is 2 inches enough or better to double it? Appreciate it. Please share any link if somebody did use this to make panels.


----------



## nathan_h

sukumar said:


> I am considering cotton for acoustic panels. How do you compare it with polyester or foam? Is 2 inches enough or better to double it? Appreciate it. Please share any link if somebody did use this to make panels.


 http://www.bobgolds.com/AbsorptionCoefficients.htm 

Most foam is not great. There is some specialist foam that costs twice what insulation (rockwool or fiberglass) costs that can work okay. 

I don't know what kind of cotton panels you are thinking of. The ones I have seen also cost more than insulation, for less peformance.

You can see from that link that the best materials in the 4" to 6" thickness are ideal. 

2" is often better than nothing.

Most people "compromise" and consider 3.5 to 4" to be "Good Enough" and get good results.


----------



## squared80

sukumar said:


> I am considering cotton for acoustic panels.


If you're going to do acoustic panels, then use something more effective. And ignore that YouTube video with the guy that uses towels.


----------



## sukumar

nathan_h said:


> http://www.bobgolds.com/AbsorptionCoefficients.htm
> 
> Most foam is not great. There is some specialist foam that costs twice what insulation (rockwool or fiberglass) costs that can work okay.
> 
> I don't know what kind of cotton panels you are thinking of. The ones I have seen also cost more than insulation, for less peformance.
> 
> You can see from that link that the best materials in the 4" to 6" thickness are ideal.
> 
> 2" is often better than nothing.
> 
> Most people "compromise" and consider 3.5 to 4" to be "Good Enough" and get good results.


Thanks. That link bobgolds is pointing to this link cotton which shows cotton is better or equal to fiber glass






Acousticotton - a recycled cotton acoustic wall panel for reflections, reverberation & noise control. This acoustic treatment material is an excellent acoustic product. This sound insulation product has superior sound absorption NRC to fiberglass.


Acousticotton - a recycled cotton acoustic wall panel for reflections, reverberation & noise control. This acoustic treatment material is an excellent acoustic product. This sound insulation product has superior sound absorption NRC to fiberglass.



www.acousticotton.com


----------



## nathan_h

sukumar said:


> Thanks. That link bobgolds is pointing to this link cotton which shows cotton is better or equal to fiber glass
> 
> 
> 
> 
> 
> 
> Acousticotton - a recycled cotton acoustic wall panel for reflections, reverberation & noise control. This acoustic treatment material is an excellent acoustic product. This sound insulation product has superior sound absorption NRC to fiberglass.
> 
> 
> Acousticotton - a recycled cotton acoustic wall panel for reflections, reverberation & noise control. This acoustic treatment material is an excellent acoustic product. This sound insulation product has superior sound absorption NRC to fiberglass.
> 
> 
> 
> www.acousticotton.com
> 
> 
> 
> 
> 
> View attachment 3372107


Yes it certainly is possible for some specialized panels made from cotton fibers to work as good as fiberglass.
Note that it costs at least twice as much as fiberglass for equivalent impact when I looked into it.

Be careful: Just going and getting cotton material is not nearly as effective. And may present a fire hazard.

And, finally, personally I would not trust any place that doesn’t have actual third party test results.


----------



## Loonster

I'm planning on making panels out of ROCKWOOL SAFE 'n' SOUND (3" x 15.25" x 47"). I plan on cutting them in half, so (3" x 15.25" x 23.5"). I would prefer 2'x4' panels, but those are unavailable in my area unless I order a large order.

What should the inside dimensions be of box they should fit in? 

They are designed to go in 2x4 construction 16" OC. So the normal width of the space would be 14.5". I assume I will want somewhat of a snug fit to keep them in place, but maybe not as snug of a fit as is used in construction. Maybe 15" x 23"?

For thickness, I'm thinking I may want it a little deeper to avoid a bulge in the image. Maybe 3.25?

Is it worthwhile to drill holes in the side panels? If so, how big of holes and spacing?



I am planning on using a construction technique similar to : 






My frame in the back will be made of 1"x3", and I will probably use 1/4" underlayment plywood for the sides


----------



## nathan_h

Strongly recommend you get something more rigid, like the rockwool safe and sound COMFORTBOARD, Owens Corning 703, or similar. You won’t find this at Home Depot etc but every HVAC supply house will have some version for sale.


----------



## squared80

Loonster said:


> I'm planning on making panels out of ROCKWOOL SAFE 'n' SOUND (3" x 15.25" x 47"). I plan on cutting them in half, so (3" x 15.25" x 23.5"). I would prefer 2'x4' panels, but those are unavailable in my area unless I order a large order.
> 
> What should the inside dimensions be of box they should fit in?
> 
> They are designed to go in 2x4 construction 16" OC. So the normal width of the space would be 14.5". I assume I will want somewhat of a snug fit to keep them in place, but maybe not as snug of a fit as is used in construction. Maybe 15" x 23"?
> 
> For thickness, I'm thinking I may want it a little deeper to avoid a bulge in the image. Maybe 3.25?
> 
> Is it worthwhile to drill holes in the side panels? If so, how big of holes and spacing?
> 
> 
> 
> I am planning on using a construction technique similar to :
> 
> 
> My frame in the back will be made of 1"x3", and I will probably use 1/4" underlayment plywood for the sides


I used plain old pink fluffy for a couple of mine, because I had extra. But using Rockwool 60 boards for the rest, and those are much easier. Friction fit and stay rigid. I suggest that or OC 703.


----------



## Loonster

squared80 said:


> I used plain old pink fluffy for a couple of mine, because I had extra. But using Rockwool 60 boards for the rest, and those are much easier. Friction fit and stay rigid. I suggest that or OC 703.


How much of a friction fit?

The cheapest source for OC 703 panels I found is online. Around $125 for 6 sheets. Rockwool 60 would be around $95.

If I use this insulation, I think I would either need to double up, or put a cheaper piece of insulation behind the panel to get my desired thickness.


----------



## mikela

Loonster said:


> How much of a friction fit?
> 
> The cheapest source for OC 703 panels I found is online. Around $125 for 6 sheets. Rockwool 60 would be around $95.
> 
> If I use this insulation, I think I would either need to double up, or put a cheaper piece of insulation behind the panel to get my desired thickness.


I used Knauf Ecose panels from ATS Acoustics at $94 for 6. I just doubled them up and wrapped them in black burlap. I used Roto fasteners on the back to attach to the wall. No frame.


----------



## shivaji

...


----------



## confinoj

Not sure if I've seen any definitive answers to this question. I worked with GIK for an acoustic panel plan for my room. I have an AT screen and behind the screen wall is an additional 3ft of space although ceiling height and width is less than the rest of the room. I have my LCR (Revel F36) and one of my SVS PC-4000 subs behind screen. Before talking with GIK I had purchased 6 4"x48"x24" bare OC703 panels and have them against the back wall. GIK advised leaving those panels but also filling much of the rest of the space with pink insulation loosely stuffed in large plastic garbage bags for a large cheap bass trap. I have done some of this (using unfaced rolls of R30) but still working on it. I'm assuming bass frequencies will pass through the plastic and direct air to insulation contact is not necessary? I also wondered if the plastic is going to _increase _the reflections of higher frequencies behind the screen? I have been trusting that GIK knows what they are talking about and was appreciative of them not trying to sell me bass traps for behind the screen. It's a very easy solution so hoping it is reasonable advice. Any thoughts on this?


----------



## nathan_h

That is reasonable advice. However, you are right: The plastic will reflect some of the highest frequencies. Sometimes that is a good thing but in general right behind a screen I like to kill those high frequencies too that can be bouncing off the screen back towards the speakers/front wall and creating comb filter. 

So what I would do is put those nice OC073 panels IN FRONT of the batts of insulation. Might need some modest framing, and might want to cover with simple cheap wide weave fabric like black muslin.

And it will probably be no different from what GIK has recommended.


----------



## confinoj

nathan_h said:


> That is reasonable advice. However, you are right: The plastic will reflect some of the highest frequencies. Sometimes that is a good thing but in general right behind a screen I like to kill those high frequencies too that can be bouncing off the screen back towards the speakers/front wall and creating comb filter.
> 
> So what I would do is put those nice OC073 panels IN FRONT of the batts of insulation. Might need some modest framing, and might want to cover with simple cheap wide weave fabric like black muslin.
> 
> And it will probably be no different from what GIK has recommended.


Thanks. That makes sense although a little harder to have panels just free floating in the middle of that space. Since otherwise the advise is reasonable I'll finish with the current plan and just see where I wind up subjectively, what I see on Audyssey multeq-X data, and at some point REW and adjust from there if problematic.


----------



## sukumar

Looks like Denim untratouch insultion is discontinued. I am planning only eco friendly no itch stuff. I found the following *Frost King CF1 No itch natural cotton*


https://www.amazon.com/Frost-King-CF1-Multi-Purpose-Insulation/dp/B004Y6SX1Y

Appreciate any thoughts on this for acoustic treatement.


----------



## squared80

sukumar said:


> Looks like Denim untratouch insultion is discontinued. I am planning only eco friendly no itch stuff. I found the following *Frost King CF1 No itch natural cotton*
> 
> 
> https://www.amazon.com/Frost-King-CF1-Multi-Purpose-Insulation/dp/B004Y6SX1Y
> 
> Appreciate any thoughts on this for acoustic treatement.


Well, it's only 1" thick, and I don't know how dense it is. Would need good support so it doesn't sag or fall down. I would lean towards tried and true, but interested to see how you work with this material if you get it.


----------



## sukumar

squared80 said:


> Well, it's only 1" thick, and I don't know how dense it is. Would need good support so it doesn't sag or fall down. I would lean towards tried and true, but interested to see how you work with this material if you get it.


Glad you got a good point. I can do 2 inches or 3inch. First, we will put in the windows and see how it works. Need to figure out how dense. Maybe will call the company today.


----------



## jaysoffian

@Loonster I made my panels on the cheap. MDF frames, Safe N Sound, landscaping cloth and burlap on the back, some breathable stretch fabric I found at Joann.

I cut down 16" x 4' x 3/4" MDF shelving to 3" x 47" x 3/4" to build my frames. Believe it or not I did this with a rotary saw and a jig I made from fiber board. I built six panels. Five are 47" x 32" x 3" (outside dimensions) and hold two batts each. One had to hang on a door and is 47" x 28" x 3" so I cut one of the batts for width. It’s easy to cut with an insulation knife. Hung with Z clips. The front of the frame has a bar across the width that's about 3/4" by 3/4" to hold the insulation in place. The back is held by the burlap/landscaping cloth. (I started with landscaping cloth but decided it wasn't durable enough so I put burlap over it.) I also used a hand stapler but that was a huge mistake. Invest is a compressor and a pneumatic stapler if you value your sanity.

The frames are held together using pocket screws and glue. You'll need to buy a Kreg jig for that.


----------



## nathan_h

jaysoffian said:


> @Loonster I made my panels on the cheap. MDF frames, Safe N Sound, landscaping cloth and burlap on the back, some breathable stretch fabric I found at Joann.
> 
> I cut down 16" x 4' x 3/4" MDF shelving to 3" x 47" x 3/4" to build my frames. Believe it or not I did this with a rotary saw and a jig I made from fiber board. I built six panels. Five are 47" x 32" x 3" (outside dimensions) and hold two batts each. One had to hang on a door and is 47" x 28" x 3" so I cut one of the batts for width. It’s easy to cut with an insulation knife. Hung with Z clips. The front of the frame has a bar across the width that's about 3/4" by 3/4" to hold the insulation in place. The back is held by the burlap/landscaping cloth. (I started with landscaping cloth but decided it wasn't durable enough so I put burlap over it.) I also used a hand stapler but that was a huge mistake. Invest is a compressor and a pneumatic stapler if you value your sanity.
> 
> The frames are held together using pocket screws and glue. You'll need to buy a Kreg jig for that.
> 
> View attachment 3376836
> View attachment 3376835
> View attachment 3376837
> View attachment 3376838
> View attachment 3376834
> View attachment 3376847
> View attachment 3376848
> View attachment 3376863


And that's how it's done on a budget but with great results. Very nice!

(Although I bet that cutting that MDF wasn't fun.)


----------



## confinoj

nathan_h said:


> That is reasonable advice. However, you are right: The plastic will reflect some of the highest frequencies. Sometimes that is a good thing but in general right behind a screen I like to kill those high frequencies too that can be bouncing off the screen back towards the speakers/front wall and creating comb filter.
> 
> So what I would do is put those nice OC073 panels IN FRONT of the batts of insulation. Might need some modest framing, and might want to cover with simple cheap wide weave fabric like black muslin.
> 
> And it will probably be no different from what GIK has recommended.


Just thinking about the easiest way to modify this plan to still use the garbage bags of pink insulation for bass trapping yet not negatively effect high frequency reflections from the plastic. As noted I have the bare 4" thick 703 panels against the wall currently. I still have 8 more bags to put in this area but those will block the 703 panels. I don't think it would be straight forward to have those panels, even if covered, in front of the bags as they will have no support. Would putting small perforations in the plastic bags help? Finding large cotton bags to put plastic bags in? Also of note when I last ran Aydyssey I had some significant dips in the 400-600hz region from the center speaker. I moved that bag right behind the center speaker in pic and it did improve on another run of Audyssey. Don't know if it was related or just variance in mic position but interesting. Thanks all.


----------



## nathan_h

Fabric bags instead of plastic might do the trick if it is a wide weave fabirc like muslin. Or a simple wood frame for the OC703 panels that holds them in front of the bagged insulation. Or possibly unbag the insulation and just hang a fabric wall (again something like black muslin or something fire rated, even better) between the insulation and the speakers.

Also those bags look pretty tightly packed? You want it nice and loose if possible. I think that is why people often just stack the batts and net them in place. Or stack them on cheap shelving and net them, if the stack is tall, for more air and stability.

See an interesting discussion: Safety of Filling Behind-Screen False Wall Cavity with...

But yes as you are already seeing, the insulation increase in that space will help the whole room sound better so I suspect the effort will be worth it.


----------



## Thalguy

Is there a good resource that explains the difference between a combo absorber with scatter plate and a diffuser? I've listened to a lot of Audioholics series with Anthony Grimani but I haven't gotten a good clear answer yet. I do have two more episodes to listen to so perhaps I just haven't gotten there yet.


----------



## nathan_h

I don't think you'll find your answer there (which tells you something: Grimani designs world class rooms for large sums of money that measure well and win awards.....and got into a huge amount of detail in this video series, and doesn't think it made the cut in terms what to discuss or include here....)

TLDR,

1) they each work in differing amounts on differing frequencies,

2) a scatter plate works less thoroughly but with much less space and expense, and

3) if your room is so good that the difference between them matters, you've exceeded the quality of most rooms discussed in this forum by a wide margin including many rooms that were designed by acoustics experts costing hundreds of thousands of dollars.

If for academic purposes you want to learn more, *and it is an interesting topic*, I think that Alton Everest's book on acoustics might be the ideal resource: Master Handbook of Acoustics, Seventh Edition: Everest, F. Alton, Pohlmann, Ken: 9781260473599: Amazon.com: Books


----------



## confinoj

nathan_h said:


> Fabric bags instead of plastic might do the trick if it is a wide weave fabirc like muslin. Or a simple wood frame for the OC703 panels that holds them in front of the bagged insulation. Or possibly unbag the insulation and just hang a fabric wall (again something like black muslin or something fire rated, even better) between the insulation and the speakers.
> 
> Also those bags look pretty tightly packed? You want it nice and loose if possible. I think that is why people often just stack the batts and net them in place. Or stack them on cheap shelving and net them, if the stack is tall, for more air and stability.
> 
> See an interesting discussion: Safety of Filling Behind-Screen False Wall Cavity with...
> 
> But yes as you are already seeing, the insulation increase in that space will help the whole room sound better so I suspect the effort will be worth it.


I was just thinking that GIK said use “lawn and leaf bags”. They also said used unfaced insulation which I did. I bought plastic leaf bags but they may have been envisioning the paper type initially. They know I wound up using plastic bags (as I had asked about reflections off the plastic) and didn’t say anything but wondering if paper bags would have been worked better in regard to minimizing high frequency reflections.


----------



## sdurani

confinoj said:


> They know I wound up using plastic bags (as I had asked about reflections off the plastic) and didn’t say anything but wondering if paper bags would have been worked better in regard to minimizing high frequency reflections.


The point of using plastic is to reflect mid to high frequencies, assuming your goal is to make bass traps and not broadband absorbers (too many of which can result in a dull sounding room).


----------



## confinoj

sdurani said:


> The point of using plastic is to reflect mid to high frequencies, assuming your goal is to make bass traps and not broadband absorbers (too many of which can result in a dull sounding room).


Yes the goal per GIK was just bass traps. What nathan_h was concerned about was if high frequency reflections behind the screen would be adversely affected by the plastic. I have 6 4” 48x24” OC703 panels on the wall (see pic) but as I fill up the space with more bags (per GIKs advice) the bags will block the panels potentially limiting their impact. Those panels definitely helped with behind the screen reflections subjectively when I put them up. Do you feel similarly that they will negatively affect the highs if I keep filling the space?


----------



## confinoj

nathan_h said:


> Also those bags look pretty tightly packed? You want it nice and loose if possible. I think that is why people often just stack the batts and net them in place. Or stack them on cheap shelving and net them, if the stack is tall, for more air and stability.


They are fairly loosely packed actually. One roll filled 2 bags. I just folded it like an accordion trying not to compress it.


----------



## sdurani

confinoj said:


> Do you feel similarly that they will negatively affect the highs if I keep filling the space?


Yes. I would stick with broadband absorption on the front wall (at least between the L/C/R speakers) to minimize muddying the front soundstage.


----------



## confinoj

sdurani said:


> Yes. I would stick with broadband absorption on the front wall (at least between the L/C/R speakers) to minimize muddying the front soundstage.


Got it thanks. What I did for now was re-arrange bags so they are mostly well below tweeter level leaving a good portion of the OC703 panels unobstructed. I didn't use all of them but still have 13 bags overall mostly in the lower 1/3 (height wise) of that space. So still quite a bit of bass trapping with hopefully not too much impact on highs. I'll see how this sounds and what kind of measurements I see in Multeq-X and eventually will get some REW data. I'll alter the plan if it sounds or looks poor. Subjectively watching a movie tonight (without re-calibrating) everything was sounding quite good.


----------



## nathan_h

That's the right result. An easy way to assess the setup:

As long as what your eyes from your seat can see is not the bags, but the exposed 703, you should be good. If the bags obscure the 703, that's an indication that the treble can't get there, either.


----------



## Loonster

nathan_h said:


> I don't think you'll find your answer there (which tells you something: Grimani designs world class rooms for large sums of money that measure well and win awards.....and got into a huge amount of detail in this video series, and doesn't think it made the cut in terms what to discuss or include here....)
> 
> TLDR,
> 
> 1) they each work in differing amounts on differing frequencies,
> 
> 2) a scatter plate works less thoroughly but with much less space and expense, and
> 
> 3) if your room is so good that the difference between them matters, you've exceeded the quality of most rooms discussed in this forum by a wide margin including many rooms that were designed by acoustics experts costing hundreds of thousands of dollars.
> 
> If for academic purposes you want to learn more, *and it is an interesting topic*, I think that Alton Everest's book on acoustics might be the ideal resource: Master Handbook of Acoustics, Seventh Edition: Everest, F. Alton, Pohlmann, Ken: 9781260473599: Amazon.com: Books


Thank you for the book recommendation. I have ordered it and will browse through it before I actually build any panels.

I've watched nearly every video I could find with Anthony Grimani. I learned quite a bit from the videos. It drove an interest strong enough that I bought Floyd Toole's book. And now that I have read a good portion of Toole's book, I realized that Grimani most just restates what is in Toole's book in a more accessible manner.


----------



## nathan_h

Loonster said:


> Thank you for the book recommendation. I have ordered it and will browse through it before I actually build any panels.
> 
> I've watched nearly every video I could find with Anthony Grimani. I learned quite a bit from the videos. It drove an interest strong enough that I bought Floyd Toole's book. And now that I have read a good portion of Toole's book, I realized that Grimani most just restates what is in Toole's book in a more accessible manner.


And to be fair Toole mostly just summarizes other people’s studies and pulls together the implications of their research. But he does it well!


----------



## hokeyplyr48

loosely related to acoustic treatments, has anyone ordered from these folks: TW-100 Half-Inch Fabric Mounting Track / Price per foot $1.75 - Price per five foot segment $8.75

Looking to use this instead of “fabric mate” track to hide my panels on the wall.


----------



## Duc Vu

So I'm back. 2 months after posting questions here about acoustic treatment for my room. Since then, I have made several absorption panels and put them up on the wall.

Three 60x120cm panels (4" thick wockwool, 4" spaced off wall) behind front and center speakers to treat SBIR. The back of the speakers are very close to the surface of the panels.










Two 30x120cm panels (4" thick rockwool, 4" spaced off wall) on the left side wall/doors to treat 1st reflection points from center, front right and surround right speaker.









Two 30x120cm panels (2" thick rockwool, 2" spaced off wall) on the back closet to the side of the surround speakers to treat 1st reflection points from those. Two 30x120cm panels (4" thick rockwool, 4" spaced off wall) behind main listening position to treat 1st reflection points from front speakers. And also two 4" thick 30x120cm panels behind the surround speakers to treat SBIR.










For the right side wall, since it's further from the main listening position compared to the left wall/doors by quite an amount, I don't place any absorption panels there.









As for bass traps, I ran out of rockwool so I can only put up two 30x120cm panels (6" thick rockwool) on the two opposite corners where I plan to place the dual subs.
















There will be two more 2" thick 60x120cm panels on the ceiling. Currently they aren't hanged yet. The ceiling is around 3.5m high and those will be hanged at 20cm from the ceiling.

I did some quick movie test and found it disappointing. I don't know why but the bass now seems sloppy and not as impactful as before. I then removed all the panels from the room to compare. Only then I realize how terribly echoey the room is without treatment. But when it comes to movie test, the powerful bass is back. And the sound is big and exciting. Moving the panels back to the room and the sound is a lot more focused and intimate, and maybe there is more clarity and details to the sound (need more testing), but the bass doesn't have that punch to it.

Here are some graphs for comparison. Note that Audyssey is turned off here and all the settings are reverted back to defaults:
*RT60 Decay (center speaker):
-without treatment:








-with treatment:









So it seems overall decay time is reduced from around 600-700 ms to 300-400ms for 100Hz and up. Pretty good. I ignore the graph below 100Hz because Audioholics say it is not very accurate.

*Frequency response (center speaker):
RED is without treatment, WHITE is with treatment








Doesn't seem much is changed in the bass department. I thought putting the panel behind the center speaker to treat SBIR would fix some of the nulls near and above the crossover frequency, but those nulls are still there.

So yeah... Will need to do more tests but so far I like that the sound is more focused, dialogue is probably clearer, and imaging is probably better, but dislike the reduced soundstage, and that bass problem. I don't think I have overdone with the absorption, and the panels are reasonably thick/spaced off wall and strategically placed to not throw off the low-mid-high balance of the room. I wish I had some diffusers, but those are complicated to DIY. More bass traps to cover all corners from floor to ceiling would be more ideal, but that would cost more time and money, and I'm not sure if 6" is even enough thickness for bass trap. I don't have space for thicker than 6" panels.

Maybe after hanging the ceiling panels and put everything properly back in place, I will run Audyssey and see if things improve.

Any comments/suggestions?


----------



## nathan_h

Duc Vu said:


> So I'm back. 2 months after posting questions here about acoustic treatment for my room. Since then, I have made several absorption panels and put them up on the wall.
> 
> Three 60x120cm panels (4" thick wockwool, 4" spaced off wall) behind front and center speakers to treat SBIR. The back of the speakers are very close to the surface of the panels.
> View attachment 3379821
> 
> 
> 
> Two 30x120cm panels (4" thick rockwool, 4" spaced off wall) on the left side wall/doors to treat 1st reflection points from center, front right and surround right speaker.
> View attachment 3379822
> 
> 
> Two 30x120cm panels (2" thick rockwool,2" spaced off wall) on the back closet to the side of the surround speakers to treat 1st reflection points from those. Two 30x120cm panels (4" thick rockwool,4" spaced off wall) behind main listening position to treat 1st reflection points from front speakers. And also two 4" thick 30x120cm panels behind the surround speakers to treat SBIR.
> 
> View attachment 3379825
> 
> 
> For the right side wall, since it's further from the main listening position compared to the left wall/doors by quite an amount, I don't place any absorption panels there.
> View attachment 3379827
> 
> 
> As for bass traps, I ran out of rockwool so I can only put up two 30x120cm panels (6" thick rockwool) on the two opposite corners where I plan to place the dual subs.
> View attachment 3379829
> View attachment 3379830
> 
> 
> There will be two more 2" thick 60x120cm panels on the ceiling. Currently they aren't hanged yet. The ceiling is around 3.5m high and those will be hanged at 20cm from the ceiling.
> 
> I did some quick movie test and found it disappointing. I don't know why but the bass now seems slopy and not as impactful as before. I then removed all the panels from the room to compare. Only then I realize how terribly echoey the room is without treatment. But when it comes to movie test, the powerful bass is back. And the sound is big and exciting. Moving the panels back to the room and the sound is a lot more focused and intimate, and maybe there is more clarity and details to the sound (need more testing), but the bass doesn't have that punch to it.
> 
> Here are some graphs for comparison. Note that Audyssey is turned off here and all the settings are reverted back to defaults:
> *RT60 Decay (center speaker):
> -without treatment:
> View attachment 3379841
> 
> -with treatment:
> View attachment 3379843
> 
> 
> So it seems overall decay time is reduced from around 600-700 ms to 300-400ms for 100Hz and up. Pretty good. I ignore the graph below 100Hz because Audioholics say it is not very accurate.
> 
> *Frequency response (center speaker):
> RED is without treatment, WHITE is with treatment
> View attachment 3379846
> 
> Doesn't seem much is changed in the bass department. I thought putting the panel behind the center speaker to treat SBIR would fix some of the nulls near and above the crossover frequency, but those nulls are still there.
> 
> So yeah... Will need to do more tests but so far I like that the sound is more focused, dialogue is probably clearer, and imaging is probably better, but dislike the reduced soundstage, and that bass problem.
> 
> Any comments/suggestions?



Okay, this is great info, and it is excellent that you have found two specific areas that you care about.

SOUND STAGE WIDTH

Yes, this is not surprising that the sound stage is less wide. I looked closely at your graphs and you are at or below 0.2 seconds on that waterfall, which is very dry. Even commercial recording studios are not quite that dry. 0.3 would make more sense in your room. And this is easy to achieve:

Try placing strips of cardboard across the front of the panels that are on the *side* walls. This will re-introduce some of the open sound by increasing the reflection of some high frequencies. Here is a concept photo, but really, just doing strips that are 5cm wide then 5cm gap of cardboard will let you test this idea.











BASS

I hate to be simple and there may be various things going on here. But before we get complicated (sometimes cleaning up the distortion -- excessive reflections -- in the room like you have done can make the bass sound different; sometimes sitting in a null can remove the punch; etc) let's try something simple:

Turn up the sub 6db on the AVR trim after running Audessey.

If that doesn't help, the using the Audessey editor app to create a custom curve at 100hz and below, that rises 6 or 8 db from 100hz down to 20hz will probably help.


----------



## nathan_h

Duc Vu said:


> *Frequency response (center speaker):
> RED is without treatment, WHITE is with treatment
> 
> 
> 
> 
> 
> 
> 
> 
> Doesn't seem much is changed in the bass department. I thought putting the panel behind the center speaker to treat SBIR would fix some of the nulls near and above the crossover frequency, but those nulls are still there.



This is not your center speaker. This is your center speaker PLUS your subwoofer.

Turn off the subwoofer output and run the center full range, then measure.

(Also, please use psychoacoustic smoothing option in REW, which will more accurately report what human ears hear.)

---

If you want a quick and easy experiment, I would try changing your crossover to 100 or 120hz. That might work a whole lot better.


----------



## Duc Vu

nathan_h said:


> Okay, this is great info, and it is excellent that you have found two specific areas that you care about.
> 
> SOUND STAGE WIDTH
> 
> Yes, this is not surprising that the sound stage is less wide. I looked closely at your RT60 times and you are at or below 0.2 seconds, which is very dry. Even commercial recording studios are not quite that dry. 0.3 would make more sense in your room.
> 
> Try placing strips of cardboard across the front of the panels that are on the *side* walls. This will re-introduce some of the open sound by increasing the reflection of some high frequencies. Here is a concept photo, but really, just doing strips that are 5cm wide then 5cm gap of cardboard will let you test this idea.
> 
> View attachment 3379861
> 
> 
> 
> BASS
> 
> I hate to be simple and there may be various things going on here. But before we get complicated (sometimes cleaning up the distortion -- excessive reflections -- in the room like you have done can make the bass sound different; sometimes sitting in a null can remove the punch; etc) let's try something simple:
> 
> Turn up the sub 6db on the AVR trim after running Audessey.
> 
> If that doesn't help, the using the Audessey editor app to create a custom curve at 100hz and below, that rises 6 or 8 db from 100hz down to 20hz will probably help.


Hmm my RT60 Decay graph shows that most are above 0.3 and averaged at 0.4.

The cardboard trick seems interesting. I will look into it. But isn't the point of treating 1st reflection is to absorb those high frequencies?

The sitting position doesn't change when I compare the bass without treatment and with treatment. So it is definitely caused by the panels. Maybe like you said, removing distortion makes the bass sound different, but I thought different here should mean better. Never thought absorption panels would worsen the bass.


----------



## nathan_h

Duc Vu said:


> Hmm my RT60 Decay graph shows that most are above 0.3 and averaged at 0.4.
> 
> The cardboard trick seems interesting. I will look into it.
> 
> The sitting position doesn't change when I compare the bass without treatment and with treatment. So it is definitely caused by the panels. Maybe like you said, removing distortion makes the bass sound different, but I thought different here should mean better. Never thought absorption panels would worsen the bass.


Sorry, I only see the waterfall graph and the sound seems to drop below the level of the graph at .2 seconds.

"Never thought absorption panels would worsen the bass."

Hmmm, well, I don't know what "worse" means. 

But I know what "accurate" means and you can measure that. You can determine whether the subwoofer is accurately producing the bass signal. That's an easy, yes or no or how close to accurate it is.

*Then, if you want "more" bass, you can use the EQ to get that. If you want more slam in the chest (gunshots) then raising 50hz is a great option. If you want more rumble, then raising 30hz or even 20hz is good. If you want more "full" sound, then raising 80 to 120hz is good. Etc.*


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## Duc Vu

nathan_h said:


> .
> "Never thought absorption panels would worsen the bass."
> 
> Hmmm, well, I don't know what "worse" means.
> 
> But I know what "accurate" means and you can measure that. You can determine whether the subwoofer is accurately producing the bass signal. That's an easy, yes or no or how close to accurate it is.


That's what I want to know for a long time. How do I know if I'm getting accurate bass? 

Besides, I want to figure out why adding absorption panels change the perception of bass that much without altering the low frequency response...


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## sdurani

Duc Vu said:


> How do I know if I'm getting accurate bass?


One way is to compare input to output. If you're sending a swept signal to your subwoofer(s) that is a straight line (same level at all frequencies), then the closer the output is to a smooth/straight line, the more accurate it is. Once you do the best you can to get the bass accurate (fewest/smallest peaks & dips), you can shape the bass to your personal preference (using either tone controls or adjusting the target curve).


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## Duc Vu

sdurani said:


> One way is to compare input to output. If you're sending a swept signal to your subwoofer(s) that is a straight line (same level at all frequencies), then the closer the output is to a smooth/straight line, the more accurate it is. Once you do the best you can to get the bass accurate (fewest/smallest peaks & dips), you can shape the bass to your personal preference (using either tone controls or adjusting the target curve).


How loud should the input/swept signal be, and at what level of db should the output/straight line be at to correspond?

For example, if I run a -15dbfs sweep in REW with the master volume set at -15 in the avr, should I expect to get a straight line at 75db on the graph to call it accurate?

If you look at the graphs I posted above, you can see the output is far from a straight line, both before and after treatment. I'm also surprised that while the bass frequency response doesn't seem to change much, my perception of bass changes, and not in a positive way...


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## nathan_h

That is correct. An accurate response would be a line rather than hump’s and troughs. 

(Note that many of the small squiggles are inaudible hence my recommendation you smooth the response graph using the Psychoacoustic smoothing option in REW. That will ignore the inaudible humps and troughs ….. and any that remain are the ones that are worth knowing about. )

To get more detailed in the analysis, seeing a graph of the subwoofer alone would be useful. But from the graphs you posted, it doesn’t look like the subwoofer frequency response changed at all from the before and after graph.…and the rt60 time got worse.


----------



## Duc Vu

nathan_h said:


> But from the graphs you posted, it doesn’t look like the subwoofer frequency response changed at all from the before and after graph.…and the rt60 time got worse.


That rt60 decay graph behaves weirdly for below 100hz. It looks different each time I rerun the measurement and regenerate the graph, although the mic position stays the same. Audioholics in their video also say that it's not very accurate below 100Hz.


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## fattire

nathan_h said:


> That is correct. An accurate response would be a line rather than hump’s and troughs.
> 
> (Note that many of the small squiggles are inaudible hence my recommendation you smooth the response graph using the Psychoacoustic smoothing option in REW. That will ignore the inaudible humps and troughs ….. and any that remain are the ones that are worth knowing about. )
> 
> To get more detailed in the analysis, seeing a graph of the subwoofer alone would be useful. But from the graphs you posted, it doesn’t look like the subwoofer frequency response changed at all from the before and after graph.…and the rt60 time got worse.


... and ideally a look at the before / after waterfall or spectrogram.


----------



## nathan_h

Duc Vu said:


> That rt60 decay graph behaves weirdly for below 100hz. It looks different each time I rerun the measurement and regenerate the graph, although the mic position stays the same. Audioholics in their video also say that it's not very accurate below 100Hz.


Yes, not very useful. 

The frequency response of the crossover will be useful to see AFTER working on the individual elements separately.


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## Matt37

Santa came a bit late this year. Mix of GIK 4" Alpha and Impression series.


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## Duc Vu

nathan_h said:


> Yes, not very useful.
> 
> The frequency response of the crossover will be useful to see AFTER working on the individual elements separately.


After watching a few more Audioholics video with Anthony Grimani in it about bass traps, I have come to the conclusion that those 6" thick panels I put at the corners are not considered as bass traps and won't do much below 125Hz. To be able to truly manipulate subwoofer frequency of below 80Hz, I need panels of 16" thickness or more, which are just simply not practical in my room. It's probably easier to just do multi sub at this point, which will act as active bass traps to control standing waves.


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## squared80

I have a 3' wide x 4' high absorber that is 8" thick that I am putting on the center of the rear wall.

I was brainstorming ways to install it securely since it's so thick, and then I figured I'd install a few strong hooks and hang it from the ceiling with some chain (kind of like I did with my front ceiling absorbers). Plus, I can put a few inches of space between the absorber and the rear wall. The space on the rear wall in not accessible by foot traffic so nobody will be walking past it or running into it.

Anybody done something like this instead of installing it directly on the wall?


----------



## carp

Matt37 said:


> Santa came a bit late this year. Mix of GIK 4" Alpha and Impression series.
> View attachment 3380505
> 
> View attachment 3380506
> 
> View attachment 3380504


Hey @nathan_h would it be a good experiment to try placing (probably hang them from the ceiling using wires) some similar scatter plates over some of the pink fluffy insulation that is covering my front wall? It bugs me that my room measures 2.0 instead of the recommended 3.0 (I think that's what is recommended if memory serves). I like the sound now a lot and I swear it's not too dead but I'm a never ending tinker-er and always curious if things can be better. 

I have some in a closet that I'm not using, I think I have 4 2'x2' and a 12" x 48" if I remember right so that would be 20 square feet so not sure if that would do much or not.


----------



## nathan_h

Duc Vu said:


> After watching a few more Audioholics video with Anthony Grimani in it about bass traps, I have come to the conclusion that those 6" thick panels I put at the corners are not considered as bass traps and won't do much below 125Hz. To be able to truly manipulate subwoofer frequency of below 80Hz, I need panels of 16" thickness or more, which are just simply not practical in my room. It's probably easier to just do multi sub at this point, which will act as active bass traps to control standing waves.


Bingo. Multiple subs is the way to get great bass response up to a little above the crossover frequency, at which point trapping/panels become effective. Since you already know how to use REW, you have the skills needed to set up multiple subs right. 




carp said:


> Hey @nathan_h would it be a good experiment to try placing (probably hang them from the ceiling using wires) some similar scatter plates over some of the pink fluffy insulation that is covering my front wall? It bugs me that my room measures 2.0 instead of the recommended 3.0 (I think that's what is recommended if memory serves). I like the sound now a lot and I swear it's not too dead but I'm a never ending tinker-er and always curious if things can be better.
> 
> I have some in a closet that I'm not using, I think I have 4 2'x2' and a 12" x 48" if I remember right so that would be 20 square feet so not sure if that would do much or not.


.36 in the bass, .25 in the mids and treble, is about what Dolby says a mastering suite should measure. I wouldn’t adjust your room unless you are not close to that, but I understand experimentation is fun.

More info: RT60 REW and "How live / reverberant should my room...


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## carp

Oops, decimals in the wrong place. 😄
From around 200hz and above I'm right around .2


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## nathan_h

If you want to liven it up a bit I would add some slats over the side wall reflections.


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## Duc Vu

@nathan_h 
This is the post-treatment measurement of each of my speakers (full band with the sub turned off) and the sub channel separately. All of these were taken with XT32 disabled and all avr settings (distances, levels, etc.) reverted back to default. Do you mind taking a quick look and let me know your thoughts?

From the look of the RT60, I don't think the room is dead or overdamped. But someone pointed out that the mid seems to have lower decay time than the highs. Not sure if that contributes to the main problem I'm having which is congested soundscape: the overall sound field doesn't seem as wide as before and the bass also sounds less big, impactful and tactile. I will install the ceiling panels soon and rerun Audyssey with everything in place and report back next week.


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## nathan_h

Yeah, it really doesn't look bad at all.

For example, here is your left and right and sub in separate colors, with psychoacoustic smoothing enabled. You have no giant problematic dips, and your room EQ will take care of those peaks very nicely, I suspect, once you run it.











And then with your RT60, here is the front left speaker on it's own.

The area under 200 hz is the room modes building up. Using dual subwoofers set up correctly will be a great bonus in this room for the under 100hz area. And then the 100 to 200hz range should be something that thick panels hanging off the ceiling (ie, with an air gap, so they are effective at lower frequencies) or straddling corners (again to increas the air gap) will help with.

Above that range, things are looking pretty good, and not dead at all in my opinion. While Dolby would drive you to 250 miliseconds territorty, really anything under 500 that doesn't jump around wildly is in the realm of acceptable for a good room. Personally I would NOT cover panels with slotted cardboard at this point. You can return to that as an experiment later.










TLDR: Run the room correction process and THEN judge the sound. You have done a good job of creating a excellent foundation for the room correction to do it's stuff. 

(The only thing I would do in my room, is what you already plan: 

1. Hanging thick panels on the ceiling. This will help reduce the RT60 a little more but, more important, it will help control the bass a bit more in the 100 to c300hz region.
2. Second matching subwoofer, which will help you manage the bass in the under 100hz region.)

But both of those improvements are going to be incremental, ie, you will likely enjoy how the room sounds now, even before that, if you complete the process for the moment by running room correction.


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## Duc Vu

nathan_h said:


> Yeah, it really doesn't look bad at all.
> 
> For example, here is your left and right and sub in separate colors, with psychoacoustic smoothing enabled. You have no giant problematic dips, and your room EQ will take care of those peaks very nicely, I suspect, once you run it.
> 
> View attachment 3380814
> 
> 
> 
> And then with your RT60, here is the front left speaker on it's own.
> 
> The area under 200 hz is the room modes building up. Using dual subwoofers set up correctly will be a great bonus in this room for the under 100hz area. And then the 100 to 200hz range should be something that thick panels hanging off the ceiling (ie, with an air gap, so they are effective at lower frequencies) or straddling corners (again to increas the air gap) will help with.
> 
> Above that range, things are looking pretty good, and not dead at all in my opinion. While Dolby would drive you to 250 miliseconds territorty, really anything under 500 that doesn't jump around wildly is in the realm of acceptable for a good room. Personally I would NOT cover panels with slotted cardboard at this point. You can return to that as an experiment later.
> 
> View attachment 3380813
> 
> 
> TLDR: Run the room correction process and THEN judge the sound. You have done a good job of creating a excellent foundation for the room correction to do it's stuff.
> 
> (The only thing I would do in my room, is what you already plan:
> 
> 1. Hanging thick panels on the ceiling. This will help reduce the RT60 a little more but, more important, it will help control the bass a bit more in the 100 to c300hz region.
> 2. Second matching subwoofer, which will help you manage the bass in the under 100hz region.)
> 
> But both of those improvements are going to be incremental, ie, you will likely enjoy how the room sounds now, even before that, if you complete the process for the moment by running room correction.


The panels for the ceiling are 60cmx120cm, but only 2" thick unfortunately. They will be hanged 20cm from the ceiling. One will be placed to the front to treat reflections from fronts and center, and one to the back to treat reflections from surrounds. I have no hope that they will affect the bass region, but we will see.

You're the first person I see enable psychoacoustic smoothing. I have watched quite a handful videos and measurements and most of them don't apply any smoothing at all, yet they still manage to have their graph looked very smooth, either due to multi sub, or black magic, I don't know. My graphs without smoothing look horrible compared to theirs. Enable psychoacoustic smoothing seems to hide a lot of problematic dips, which are audible during slow frequency sweeps or even real contents, so I'm not sure this is the way to go.

I thought I did a good job by building reasonably thick panels and put them in places that are supposed to make sense, but at the moment, I don't like the sound coming out of my system. Although the overall room acoustics seems pretty good - it's quiet and accurate without feeling uncomfortable like some overdamped recording studios, but once I turn on the speakers, I miss that enveloping thunderous soundscape and bass from the previously terribly echoey room.

I will run room correction and let you know later, but I doubt it can expand the soundstage or bring the chest slamming bass back. I hope I'm wrong.


----------



## nathan_h

Duc Vu said:


> The panels for the ceiling are 60cmx120cm, but only 2" thick unfortunately. They will be hanged 20cm from the ceiling. One will be placed to the front to treat reflections from fronts and center, and one to the back to treat reflections from surrounds. I have no hope that they will affect the bass region, but we will see.


Well, hanging them like that is great. It works like a 9" bass trap in terms of the frequencies it works on. That is awesome. 

The 2" thickness means it only kills half as much of those frequencies as a 4 or 5" thick trap. But you can add more up there later, or make them thicker and get good benefit in the bass region due to how much you are hanging them (space between panel and ceiling). And if it starts to kill the high end, you can do the strips of wood or cardboard trick on the face of some of them.



Duc Vu said:


> I miss that enveloping thunderous soundscape and bass from the previously terribly echoey room.


There is no law that you need an accurate reproduction in your room! If you feel like you like it the old way, give this new way some time and then, after a month of listening to the new system (with all the pieces in place, and with room EQ enabled) you can confidently go back to the old way, knowing that you gave this approach a fair try.

No harm in liking what you like!



Duc Vu said:


> I will run room correction and let you know later, but I doubt it can expand the soundstage or bring the chest slamming bass back.


Room correction seldom extends the soundstage overall, but it can help reveal when there is a large sound stage in a recording and when there is a small soundstage in a recording. 

That is the usual reason for doing room treatments and room EQ: Hearing accurately what is in the recording. 

But some people don't love it, especially people that seek that traditional two channel big soundscape from a stereo recording feeling. This is why, for example, Revel and other folks build speakers that have accurate off axis response the mirror the on axis response. This allows you to use a little or a lot or no sound treatment on the side walls since the first reflections have the same tonal characteristic as the on axis sound. This can make the sound BIGGER due to all those reflections. It's not necessarily ACCURATE to sound that way, but many people enjoy it, especially for stereo music.

--

Chest slamming bass is easy: In your EQ program, increase the 50 hz region by 6 db. If you don't want to use the Audssey editor app, then you can just increase your subwoofer gain in the AVR trim settings (AFTER running room correction) by 6db. Not quite as surgically focused on chest slam, but it can often to the trick. 

Audyssey also has a Dynamic EQ function. So if you are not listening at level zero, that feature can help bring back the bass at lower listening levels. 

-----------


Duc Vu said:


> I hope I'm wrong.


Well, luckily you are covered:

1. If you are still not happy, after doing the treatment and running room EQ, and setting up a custom curve (often called a House Curve) to bring the elements you want into more prominence, THEN
2. You can go back to the way you had it before knowing that you have tried it both ways and found the one that you prefer. 

I'm deliberately not getting into the traditional forum game of "upgrade your speakers" or "add a sub" or "you need an amp" because it doesn't seem like that stuff it was is going on (though I would say that a second matching sub, set up well, is a good idea).

---



Duc Vu said:


> You're the first person I see enable psychoacoustic smoothing.


I'd be very wary of people that don't use this feature. I learned it from a training that Grimani did, and it really helps show the real problems versus those which are seldom worth chasing down.


----------



## Duc Vu

nathan_h said:


> But some people don't love it, especially people that seek that traditional two channel big soundscape from a stereo recording feeling. This is why, for example, Revel and other folks build speakers that have accurate off axis response the mirror the on axis response. This allows you to use a little or a lot or no sound treatment on the side walls since the first reflections have the same tonal characteristic as the on axis sound. This can make the sound BIGGER due to all those reflections. It's not necessarily ACCURATE to sound that way, but many people enjoy it, especially for stereo music.


I can understand when people use less or no absorbing panels for 1st reflections for 2 channel stereo because 2 channel stereo relies on reflections to reproduce the soundscape. For multi channel home theater system using multiple speakers, however, I figure reflections are more destructive than constructive so there should be more absorption panels and decay time should be smaller.

By the way, my front speakers are toed in by quite a large angle (I sit near the tv, facing the long side of the room) so there is no 1st reflection point of the left front on the left side wall for example. Those panels I put up on the side and the back are to treat mainly the reflection points from speakers at the _*opposite *_side, i.e. panels on the _*left *_side wall are for eliminating reflections from the _*right *_side speakers, and panels on the wardrobe in the _*back*_ are for eliminating reflections from the _*front *_speakers. So it is supposed to improve the imaging without worsening the soundstage too much. Doesn't seem to be the case in reality though.



nathan_h said:


> Chest slamming bass is easy: In your EQ program, increase the 50 hz region by 6 db. If you don't want to use the Audssey editor app, then you can just increase your subwoofer gain in the AVR trim settings (AFTER running room correction) by 6db. Not quite as surgically focused on chest slam, but it can often to the trick.


Since the loss of chess slamming bass is caused by the newly installed panels, I'd like to find a way to fix it using also panels instead of EQing, if possible.
Today I will remove all the panels from the room again and reconduct the same measurements I sent you in the last file for better comparison. I hope you then can help take a look and see which panels responsible for that change in perceptual of bass.



nathan_h said:


> Audyssey also has a Dynamic EQ function. So if you are not listening at level zero, that feature can help bring back the bass at lower listening levels.


Yeah I did turn on Dynamic EQ for most of the films I watch. Except recent Christopher Nolan movies like Tenet. There must be some issue with the IMAX version. The bass is boosted like crazy, and not in a good way. It overwhelms everything else. Disabling Dynamic EQ makes it more listenable.



nathan_h said:


> 1. If you are still not happy, after doing the treatment and running room EQ, and setting up a custom curve (often called a House Curve) to bring the elements you want into more prominence, THEN
> 2. You can go back to the way you had it before knowing that you have tried it both ways and found the one that you prefer.


All the panels cost around $250 to make in total, so not a very big amount of money. But I do regret all the time and effort I spent doing research, learning woodworking, ordering the materials, building these panels and hanging them (which is not exactly an easy feat for a DIY newbie like myself). Such as waste if I throw them all away now. But it'd be a lie to say I didn't expect that I might not like the sound post-treatment. I was mentally prepared for that possibility. Still, very disappointed. This audio hobby is frustrating.



nathan_h said:


> I'd be very wary of people that don't use this feature. I learned it from a training that Grimani did, and it really helps show the real problems versus those which are seldom worth chasing down.


I watched this video with Grimani in it and it seems he doesn't use psychoacoustic smoothing either. Basically there is a large variance of 38db in the bass frequency response graph he shows and it is indicated by him as very bad. Same if you look at mine without smoothing. There is 35db difference between the highest peak and the lowest dip. My only hope is a 2nd sub. If the 2nd sub makes it worse then I give up lol.


----------



## nathan_h

Duc Vu said:


> Since the loss of chess slamming bass is caused by the newly installed panels


I don't doubt this is what you are hearing or missing.

But I don't think I can see it in your measurements.


Duc Vu said:


> So it is supposed to improve the imaging without worsening the soundstage too much.


Improving imaging usually means more precise and specific sources of sounds. The panels should help with that.

I infer that by "worsening" you mean making it less wide/big? That makes sense. Yep, fewer reflections will let you hear only the size of the recording, which in some cases is going to be less large.



Duc Vu said:


> My only hope is a 2nd sub.


For response below 100 hz, a second sub will help. 

Note that what it will do is make the sound *consistent* from seat to seat. It will be a little more flat by having them act against one another. But that is only half the challenge.

To get the response flat, _you will* also* need to use EQ to reduce the peaks_. (In your case by EQ I mean Audyssey.) 

It is a two step process. You'll see that in the next Grimani video in that series, if you haven't already watched it:


----------



## Duc Vu

nathan_h said:


> I don't doubt this is what you are hearing or missing.
> 
> But I don't think I can see it in your measurements.


Yeah it's frustrating to not see it on graphs. As mentioned, I will remove the panels today and redo the measurements. Hopefully a comparison between pre- and post-treatment will tell us something.



nathan_h said:


> Improving imaging usually means more precise and specific sources of sounds. The panels should help with that.
> 
> I infer that by "worsening" you mean making it less wide/big? That makes sense. Yep, fewer reflections will let you hear only the size of the recording, which in some cases is going to be less large.


The panels do help with pinpointing sound sources and making dialogue clearer, from the limited listening tests I did. But in exchange, the soundstage is now reduced to a point where it feels like it's limited within a small room instead of big landscape in movies. 



nathan_h said:


> Note that what it will do is make the sound *consistent* from seat to seat. It will be a little more flat by having them act against one another. But that is only half the challenge.


Since I'm the only listener, I only care about the main seat. I plan to put the subs at opposite corners where measurements look opposite to another - peaks of one are dips of the other and vice versa. Hopefully most problematic dips will be gone without introducing new dips. Or I'm screwed.



nathan_h said:


> It is a two step process. You'll see that in the next Grimani video in that series, if you haven't already watched it:


I watched that yesterday. think I watched all Audioholics videos about bass with Grimani.


----------



## nathan_h

Duc Vu said:


> Yeah it's frustrating to not see it on graphs. As mentioned, I will remove the panels today and redo the measurements. Hopefully a comparison between pre- and post-treatment will tell us something.


Cool, be sure to leave the microphone in exactly the same spot for both the before and after measurements. Even moving a few cm can make comparisons hard.



Duc Vu said:


> Since I'm the only listener, I only care about the main seat. I plan to put the subs at opposite corners where measurements look opposite to another - peaks of one are dips of the other and vice versa. Hopefully most problematic dips will be gone without introducing new dips. Or I'm screwed.





Duc Vu said:


> I watched that yesterday. think I watched all Audioholics videos about bass with Grimani.


Awesome so you saw that using multiple subwoofers changed his graph from 38db dips to 20db dips….and the rest he did with electronic manipulation. First, time alignment of the subs, and then integration with his mains (that are set to small) using measurement with REW to set the delay, phase & crossover & EQ.

But since you are just one listener, you may not need a second sub. Rather, moving the sub and especially the seating location — and then EQ — may be enough.


----------



## fattire

Duc Vu said:


> can understand when people use less or no absorbing panels for 1st reflections for 2 channel stereo because 2 channel stereo relies on reflections to reproduce the soundscape. For multi channel home theater system using multiple speakers, however, I figure reflections are more destructive than constructive so there should be more absorption panels and decay time should be smaller.


Just FYI that your assumption could not be further from the truth. Reflections are critical to envelopment. They give us the wide sound stage and spaciousness that we typically crave in HT.

However, we have to balance envelopment and focus and there’s personal preference here. When it comes to ipsilateral first reflections, particularly of the L/R, you should experiment.

Listen to 2 channel music with no panels. Then listen to the same with the absorbers you just built. You’ll have a clear personal preference for one over the other. That’s what you should use in your HT setup.


----------



## Duc Vu

nathan_h said:


> But since you are just one listener, you may not need a second sub. Rather, moving the sub and especially the seating location — and then EQ — may be enough.


The seating location can't be changed, and I tried moving the sub around to all possible locations in the room. Below are the best ones. These measurements were taken a while ago, even before the drop ceiling was removed (due to bass rattling). I don't think they look much different now. All of them look bad.









GREEN: Sub at front left corner
YELLOW: Sub at rear right corner
BLUE: Sub at middle front wall
RED: Sub near the bed, to the right of the listening position

IF I go dual, I plan to put one sub at GREEN and one sub at YELLOW, hoping the dips will be cancelled out.


----------



## nathan_h

Good info. Those aren’t bad. Those are normal. Any room will have response like those graphs from a single sub.

I’d place the one sub in the green location and then use EQ to flatten it. Other than the dip at 25hz, EQ should be able to make that green line perfect. A second sub at the yellow location might help that 25hz dip but you won’t know until you measure them together.


----------



## Duc Vu

fattire said:


> Just FYI that your assumption could not be further from the truth. Reflections are critical to envelopment. They give us the wide sound stage and spaciousness that we typically crave in HT.
> 
> However, we have to balance envelopment and focus and there’s personal preference here. When it comes to ipsilateral first reflections, particularly of the L/R, you should experiment.
> 
> Listen to 2 channel music with no panels. Then listen to the same with the absorbers you just built. You’ll have a clear personal preference for one over the other. That’s what you should use in your HT setup.


I am actually not knowledgeable enough to make those assumptions. I get them from watching one of Audioholics videos. The main guy there (Gene, is it his name?) was the one who said that, and I believe Grimani also agrees. My only assumption is those guys know what they're talking about.

It's true that we should not eliminate all reflections like in an anechoic chamber because most of our listening rooms are small and we want the room to sound larger than it is to fit the contents we are watching, and humans are used to hearing reflections in real life. But how to balance between envelopment and focus/imaging? If you look at my room and the panels I hang, do you think that's too much absorption? Most of them are not even for treating ipsilateral first reflections, but for treating contralateral first reflections and SBIR. There are plenty of hard surfaces left in my room on the hardwood floor, brick walls, concrete ceilings, wooden doors, wardrobe, tv, etc that are supposed to scatter reflections like crazy. My decay time in my room now hovers around 300-400ms, so it's not dead. So what is wrong here?

Lastly, I don't know why I should test 2 channel music when most of what I watch are dolby atmos/multi-channel movies.


----------



## Duc Vu

fattire said:


> Just FYI that your assumption could not be further from the truth. Reflections are critical to envelopment. They give us the wide sound stage and spaciousness that we typically crave in HT.
> 
> However, we have to balance envelopment and focus and there’s personal preference here. When it comes to ipsilateral first reflections, particularly of the L/R, you should experiment.
> 
> Listen to 2 channel music with no panels. Then listen to the same with the absorbers you just built. You’ll have a clear personal preference for one over the other. That’s what you should use in your HT setup.


I am actually not knowledgeable enough to make those assumptions. I get them from watching one of Audioholics videos. The main guy there (Gene, is it his name?) was the one who said that, and I believe Grimani also agrees. My only assumption is those guys know what they're talking about.

It's true that we should not eliminate all reflections like in an anechoic chamber because most of our listening rooms are small and we want the room to sound larger than it is to fit the content we are watching, and humans are used to hearing reflections in real life. But how to balance between envelopment and focus/imaging? If you look at my room and the panels I hang, do you think that's too much absorption? Most of them are not even for treating ipsilateral first reflections, but for treating contralateral first reflections and SBIR. My decay time in my room now hovers around 300-400ms, so it's not dead. So what is wrong here?

Lastly, I don't know why I should test 2 channel music when most of what I watch is dolby atmos/multi-channel movies.


----------



## Duc Vu

nathan_h said:


> Good info. Those aren’t bad. Those are normal. Any room will have response like those graphs from a single sub.
> 
> I’d place the one sub in the green location and then use EQ to flatten it. Other than the dip at 25hz, EQ should be able to make that green line perfect. A second sub at the yellow location might help that 25hz dip but you won’t know until you measure them together.


Well I asked Ed from SVS and he told me none of them were good. But he also told me a 2nd sub may not solve that as the suck-out will always be there for the sub at that location, which is confusing.

The problem with the GREEN location is, due to the dip at around 25hz, which is near the port tuning frequency, I can hear port chuffing noise during certain movie scenes. Moving it to YELLOW for example and the chuffing noise is gone.


----------



## fattire

Duc Vu said:


> Lastly, I don't know why I should test 2 channel music when most of what I watch is dolby atmos/multi-channel movies.


Because it’s _much_ easier to hear changes and differences in sound with just 2 speakers playing vs 7 or 9 or 15. If it sounds good with 2 speakers it will sound good with many. Simplify and it will make your decisions easier.

also, reflections are not “more destructive”. I believe you may have misinterpreted what they’ve said. At least 50% of what we hear in a room are reflections and not direct sound. We need to make sure these reflections enhance what we hear. Treating contralaterals as you have done is good!

im just saying experiment with the ipsilateral. Simplify when you do and it will make hearing differences easier.Absorption will greatly increase focus. Reflection will greatly increase spaciousness.


----------



## sdurani

Duc Vu said:


> For multi channel home theater system using multiple speakers, however, I figure reflections are more destructive than constructive so there should be more absorption panels and decay time should be smaller.


Read section 9.2.1: 


https://audioroundtable.com/misc/Loudspeakers_and_Rooms.pdf


----------



## Duc Vu

One thing positive I have to say about those absorption panels on the wall is they seem to make the audio now very detailed. I test a few movie scenes that bothered me in the past with fogginess in dialogue and sound effects, but now it sounds clear and well separated.

I will remove the panels later today, redo measurements and test the same movies scenes again, and let you guys know the result. Quite a handful of panels that are hung in difficult places so it will take some time.

Until then, happy new year. And thanks @nathan_h and @fattire for helping so far.


----------



## Duc Vu

sdurani said:


> Read section 9.2.1:
> 
> 
> https://audioroundtable.com/misc/Loudspeakers_and_Rooms.pdf


oh well... I'll be damned.


----------



## sdurani

Duc Vu said:


> oh well... I'll be damned.


Some of that seems counterintuitive, but the historical research points in the same direction. Even the Dirac room correction white paper says something similar about early reflections: 

_"There seems to be consensus in the field that some early reflections actually help make speech more intelligible. However, it is also well documented that reflections within 5-10 ms of the main pulse in typical listening rooms are above the level where the primary source shifts or spreads (even when just listening to a single primary source). Reflections from the front and the rear (within ±40º) are perceived as detrimental to sound quality, whereas side reflections (within reasonable levels) often improve the perceived sound quality."_ 



https://www.dirac.com/wp-content/uploads/2021/09/On-equalization-filters.pdf


----------



## Duc Vu

sdurani said:


> Some of that seems counterintuitive, but the historical research points in the same direction. Even the Dirac room correction white paper says something similar about early reflections:
> 
> _"There seems to be consensus in the field that some early reflections actually help make speech more intelligible. However, it is also well documented that reflections within 5-10 ms of the main pulse in typical listening rooms are above the level where the primary source shifts or spreads (even when just listening to a single primary source). Reflections from the front and the rear (within ±40º) are perceived as detrimental to sound quality, whereas side reflections (within reasonable levels) often improve the perceived sound quality."_
> 
> 
> 
> https://www.dirac.com/wp-content/uploads/2021/09/On-equalization-filters.pdf


In my case, there are no 1st reflections on the side wall for the fronts because they are greatly toed in (I sit near tv, facing the long side of the room). There may be 1st reflections on the side for the center, though. Those are supposed to be absorbed by that panel on the door nearer to the front wall.











The panels you see on the left side wall (or more precisely doors) are for treating reflections from speakers on the right side (front right and surround right), which is detrimental because it skews the soundstage. As for the right side wall/doors, they are further from the MLP compared to the left side wall and there are plenty of stuff/furniture there so I don't hang any absorption panels.









The panels in the back and in the front are for SBIR and also to treat reflections from speaker on the opposite side, which is, again, detrimental.

So I don't think I have done anything too wrong here. As for the statement in that paper about early reflections helping speech more intelligible, I don't know... I haven't heard anyone mention that. I guess it makes sense if the reflections are very similar in characteristics as the primary source (as in the reflection point must be close to both the speaker and the listener, maybe?), hence they say _side reflections (within reasonable levels)_. Speech seems more intelligible with the absorption panels inside my room, though.


----------



## nathan_h

I think this wall is about right. I know the speaker is toed in so much that if doesn't feel like there are first reflections. But there are. And the amount of absorption coverage here looks about right in terms of some panels and some reflective surfaces. 

Yes, less or more might sound better or worse to you, and using your ears to decide on the right compromise makes sense for the side walls. 

But if you started by just sharing this picture, I'd say "Yep, that looks like it would be in the ballpark for a side wall."










I drew lines. The actual mirror image of the speaker/sound might not hit the wall right there. It might just be hitting next to the panel. Hard to say without being there and hanging a mirror where the panel is and seeing if you can see the speaker in the mirror while sitting in your seat.

--

The other side wall is even further away, but it will also have reflections. But treating them will be, as you have intuited, less critical. 

-----------

And then, instead of removing the panel, if you want more reflected energy, putting cardboard over some or all of the panel would give you that reflected high end energy (but still help trap some of the random acoustic energy because some sound travels through the covering, just not all of it.

I'd compromise that way first, rather than removing the panel completely, and see what you think. 

This is a popular and effective way of treating a room well without making it too dead (especially for the side walls) which is why you see professional theaters with panels like this hidden in the wall:










or panels like this on the wall:


----------



## Duc Vu

nathan_h said:


> I think this wall is about right. I know the speaker is toed in so much that if doesn't feel like there are first reflections. But there are.
> I drew lines. The actual mirror image of the speaker/sound might not hit the wall right there. It might just be hitting next to the panel. Hard to say without being there and hanging a mirror where the panel is and seeing if you can see the speaker in the mirror while sitting in your seat.


I did the mirror trick. I started seeing the front left speaker at the BLUE position, but because it is toed in a lot, I could only see its side, not its tweeter/woofer, so I assume that is not considered 1st reflection point. The tweeter/woofer of the center and the front right speaker, however, can be seen in the mirror at the RED position, so that's why I put the panel there.











nathan_h said:


> The other side wall is even further away, but it will also have reflections. But treating them will be, as you have intuited, less critical.


Yeah, there will still be some reflections there, but the energy is weaker. That right side is further away so absorption panels on only the left side will balance up the soundstage, I assume. Hanging panels in that area is also difficult due to uneven windows/door/wall surface and stuff/furniture there that can't be moved and may block the panels. If it is truly critical then I will try to manage, but it seems like my main problem lies somewhere else. I'm working on the measurements and will share with you guys soon.


----------



## sdurani

Duc Vu said:


> As for the statement in that paper about early reflections helping speech more intelligible, I don't know...


Quick and easy way to find out is to google _effects of early reflections on speech intelligibility_ and skim the results. Will take 30 seconds. 

I think you have absorption placed as well as can be in your situation. Probably the best way to get the chest slam back is to use some sort of manual EQ, whether it is tone controls or shaping the target curve, to boost certain frequencies in the bass or mid-bass range until you get the results you want. You'll also find out which range of frequencies is responsible for the chest-slam effect.


----------



## Duc Vu

@nathan_h @fattire @sdurani

So over the last 2 days, I moved the panels in and out and did measurements as well as tested familiar movie scenes. Attached are the files for five scenarios:

Without any panels
With only panels at 1st reflections
With only panels behind speakers (SBIR)
With only panels behind speakers (SBIR) and 2 panels at corner ("bass trap")
With all the panels

All these measurements were taken with Audyssey/XT32 disabled, all settings (levels, distances, etc.) reverted back to default, front and surround speakers set to Large (i.e. full band so no cross-over with the sub). Master Volume = -15, REW level = -15dBFS, sub gain = -15 (50%). Ceiling panels haven't been installed yet, and so are the atmos speakers.

Some observations:

The change in bass I noticed before between without panels vs with all panels may be due to a mistake: I enabled Dynamic EQ when I tested without panels and disabled Dynamic EQ when I tested with panels, hence the lack of chest slam bass I felt. Now I disabled Dynamic EQ for both scenarios and the bass sounds somewhat similar in terms of intensity (in terms of openness then the without panels still wins).
I don't see a lot of changes in the frequency response graph of each speaker. As for the panels that are hung behind speakers for treating SBIR, I thought they are gonna eliminate the dips in the frequency response, but no. Largely unchanged. Quite disappointing. The RT60 decay time, on the other hand, is substantially reduced, mainly for mid and high frequencies. For low frequency, those two 6" bass traps don't seem to have much effects. Should I put them somewhere else? One of the two bass traps is very near the sub, is it a bad thing? Basically, low frequency still has high RT60 decay. Only hope is multi sub.
Testing movies scenes shows that without the panels, the soundstage was very wide due to all those crazy reflections in the room. I'm aware that was not an accurate reproduction of the audio, but damn it was immersive. Imaging was also still very good. Dialogue and sound effects sometimes sounded hazy, unrealistic and echoey though. I think with all the panels installed what I have now is a much more controlled environment and what I'm hearing is closer to creators' intents probably, but that cavernous soundstage will be missed. Hopefully the atmos speakers, once installed, will bring some of the ambience back.
Next step is to finish hanging the ceiling panels as well as the atmos speakers. Run Audyssey. Watch a few movies in the next few days to get the brain used to the new listening environment. Hopefully I will like the sound then.


----------



## sdurani

Duc Vu said:


> For low frequency, those two 6" bass traps don't seem to have much effects. Should I put them somewhere else? One of the two bass traps is very near the sub, is it a bad thing?


If it doesn't have much effect, it can't be a bad thing (or a good thing).


> Testing movies scenes shows that without the panels, the soundstage was very wide due to all those crazy reflections in the room. I'm aware that was not an accurate reproduction of the audio, but damn it was immersive. Imaging was also still very good. Dialogue and sound effects sometimes sounded hazy, unrealistic and echoey though.


In that case, use a more targeted approach to placing absorption. Keep the bare walls for the ipsilateral (same side) side wall reflections so that the soundstage remains wide. Absorb the contralateral (opposite side) side wall reflections and maybe the centre speaker's first reflections. Listen to the results (don't worry so much about the measurements).


----------



## Duc Vu

sdurani said:


> If it doesn't have much effect, it can't be a bad thing (or a good thing).


So the question is: how do i make it more of a good thing?



sdurani said:


> In that case, use a more targeted approach to placing absorption. Keep the bare walls for the ipsilateral (same side) side wall reflections so that the soundstage remains wide. Absorb the contralateral (opposite side) side wall reflections and maybe the centre speaker's first reflections. Listen to the results (don't worry so much about the measurements).


Most of the panels hung on the side and rear area are for contralateral reflections and center speaker's first reflections. There are only two thinner panels on the rear area right next to the surround speakers for treating ipsilateral reflections from those speakers.


----------



## sdurani

Duc Vu said:


> So the question is: how do i make it more of a good thing?


Absorber panels aren't going to help much in the subwoofer range of bass frequencies. More effective solution is additional sub(s) and EQ.


----------



## nathan_h

Good tests!



Duc Vu said:


> I don't see a lot of changes in the frequency response graph of each speaker. As for the panels that are hung behind speakers for treating SBIR, I thought they are gonna eliminate the dips in the frequency response, but no. Largely unchanged. Quite disappointing.


I'm not seeing a lot of dips. In fact, I suspect that EQ (ie Audsyssey in your case) will flatten the peaks of a speaker like this to be within a range of 3db which is very very good.












Duc Vu said:


> The RT60 decay time, on the other hand, is substantially reduced, mainly for mid and high frequencies.


Yep, this is the main reason for panels.

Yes, thick panels behind a speaker can help tame SBIR (comb filtering) off that wall. You don't seem to have a problem with that at this point. That's great.

And yes, very thick panels can help with bass frequencies, but we are not in that realm in this room (other than potentially your ceiling panels, which will be very thick because they are hanging off the ceiling, and therefor will impact sound down below 100hz). All the panels you have so far, even the so called "bass traps" only get down to about 100hz, ie, not into the subwoofer range.



Duc Vu said:


> For low frequency, those two 6" bass traps don't seem to have much effects. Should I put them somewhere else? One of the two bass traps is very near the sub, is it a bad thing? Basically, low frequency still has high RT60 decay. Only hope is multi sub.


Multi sub may help that a bit. And EQ will be very important (seeing my comments below about Audssey).

Placement straddling a corner is useful. Remember for that there are 12 corners in a room. Floor/wall intersections and wall/ceiling intersections are just as good as a traditional corner where two walls meet. 

*But, really, your most effective bass trap will be those panels hanging from the ceiling. * The air gap between the panel and the ceiling effectively makes a 3" panel into a 12" panel (or whatever amount they are hanging down) in terms of what frequencies they act upon. At that drop, they are working in the subwoofer range. They won't solve the subwoofer response but they will lay a foundation that EQ can then complete.

(Multi subs are useful too though I'm guessing you may find that you can EQ the sub for your single seat just fine.)



Duc Vu said:


> Hopefully the atmos speakers, once installed, will bring some of the ambience back.


They probably will, especially if you use the Dolby Surround upmixer on all content.



Duc Vu said:


> Next step is to finish hanging the ceiling panels as well as the atmos speakers. Run Audyssey. Watch a few movies in the next few days to get the brain used to the new listening environment. Hopefully I will like the sound then.


Sounds like a good plan. Heck, run Audsyssey now, and then enjoy for a while before doing the ceiling. 

I guess it should go without saying but I will say it anyway:

Treating the room but not running audssey is like making a cake and eating the batter without cooking it. Yep, it can taste good. But it will be so much better after the cake goes in the oven. You have prepared a recipe and are ready to put it in the oven to finish it. Audyssey is that final step to complete the recipe.


----------



## Duc Vu

nathan_h said:


> Yes, thick panels behind a speaker can help tame SBIR (comb filtering) off that wall. You don't seem to have a problem with that at this point. That's great.


I thought there would be a substantial change in frequency response if SBIR was truly tamed, but comparing before and after graphs and I see very few positive changes, if not slightly worse. 


nathan_h said:


> Placement straddling a corner is useful. Remember for that there are 12 corners in a room. Floor/wall intersections and wall/ceiling intersections are just as good as a traditional corner where two walls meet.


Yeah but I don't have enough panels for all of those, and also hanging them at high places in the room is difficult for me. Maybe if those SBIR panels behind speakers are useless from the look of the frequency response, I may consider putting those in corners instead. 


nathan_h said:


> Multi sub may help that a bit


Honestly I'll probably just buy another sub at this point just for the sake of a complete setup, as my x3700h can independently output to 2 subs. I'm not even sure anymore if it's gonna improve the bass or not.


----------



## nathan_h

Duc Vu said:


> I thought there would be a substantial change in frequency response if SBIR was truly tamed, but comparing before and after graphs and I see very few positive changes, if not slightly worse.


How far is the front of the speaker from the wall behind it (pretend the panel isn't there)?


----------



## Duc Vu

nathan_h said:


> How far is the front of the speaker from the wall behind it (pretend the panel isn't there)?


Around 50cm for the front and center speakers. By the way the front speakers are toed in so which distance should I measure? Should I place the tape measure perpendicular to the wall behind or along the sides of the speakers? 50cm is perpendicular (photo below)


----------



## nathan_h

Acoustic center looks like about 53cm based on the photo.

You can do all the math here (SBIR calculator) but I would expect a null off the front wall about 160 hz if you have an SBIR issue. Of course there are interactions with floor, ceiling, and side wall that could change things up. 

Anyway, it still seems like SBIR is not an issue for you (at least in the post treatment measurements).


----------



## Duc Vu

nathan_h said:


> Acoustic center looks like about 53cm based on the photo.
> 
> You can do all the math here (SBIR calculator) but I would expect a null off the front wall about 160 hz if you have an SBIR issue. Of course there are interactions with floor, ceiling, and side wall that could change things up.
> 
> Anyway, it still seems like SBIR is not an issue for you (at least in the post treatment measurements).


Around 160Hz pre- and post-treatment look roughly the same. This is baffling.


----------



## nathan_h

I don't recall what material you used in the panels and how thick it is but to act well in that range would require something close to six inches thick, and with a density similar to 3.0 pcf (48 kg/m3). But I don't see a big reason to try that size out based on your measurements.


----------



## Duc Vu

nathan_h said:


> I don't recall what material you used in the panels and how thick it is but to act well in that range would require something close to six inches thick, and with a density similar to 3.0 pcf (48 kg/m3). But I don't see a big reason to try that size out based on your measurements.


ROCKWOOL Safe n Silent Pro. 40kg/m3. 4" thick, 4" away from wall.


----------



## nathan_h

Good stuff. And using a 4" thick panel with an additional 4" gap off the wall means it will get down to 100hz in effectiveness. Excellent.


----------



## Duc Vu

nathan_h said:


> Good stuff. And using a 4" thick panel with an additional 4" gap off the wall means it will get down to 100hz in effectiveness. Excellent.


It should. But I just don't see that effectiveness shown in the frequency response. Seems like there are too many other factors at play here.


----------



## *grelvis*

Greetings! I've been reading through this thread and will continue to do so. I'd also like to ask for some opinions. I've been living over in the REW thread for a while, learning to use that program and doing what I can as far as tweaking speaker placement and things like that. Unfortunately at the moment (never say never), laying the room out differently isn't an option. I'm a bit stuck with what I have.

I think I could supply anything anyone would like to see. I've learned a ton regarding the effects of speaker placement and such and what I've found is, basically, for everything I fix I just create a new issue. I've simply got a strange space to contend with. I've also evaluated my nulls and peaks vs. the calculators. For one of them (tripp) very little jives with my reality, aside from the effects of the ceiling. Another, a spreadsheet, (Barefoot) seems to pretty much nail it. I do have a strange room shape to live with. I've analyzed the major reflections and their effect but I think I see that most of them affect a range around 1k and above, and underneath that appears to be determined more by the room shape itself.

So, after a lot of investigation, I fully realize I have a big mess. I'd like to make some improvements, but I don't expect perfection. It's 95% home theater use so no worries about music quality. I don't have much if any wiggle room for layout, so it's probably diffusers or absorbers to lend some assistance here? I'm hoping so, and not too many if possible.

I have a Yamaha TSR-700 Receiver with a rather useless YPAO and limited frequencies I can EQ (63, 160, 400, 1k, 2.5k...). I have some very old (25 years?) Boston Acoustics 3-way towers (T830's), I've replaced the surrounds a while back and they actually seem to be performing well - I tried some measurements of the various drivers and before the reflections come in they are reasonably linear and I think still sound good. I don't think new speakers would help me much. Subwoofer is an SVS PB-1000.

Here's an idea of the room layout









Full Range SPL Measurements With Sub OFF









And Sub ON (Note that phase change of sub helps tame the 100Hz peaks above)









Waterfall of Left Speaker, No Sub (Right is similar, I can supply if needed)









And with Sub









Impulse Plot of Left Speaker (nothing worth noting later than this, but I can certainly supply if helpful, also Right speaker is similar). For this, I've determined that the 1st 3 spikes are due to 1) Rear wall behind couch, 2) Ceiling, 3) It's a combo ceiling then rear wall). The next around 18ms I couldn't pinpoint but it corresponds to a distance that's almost exactly double the room depth. Mid 30ms's is 4x the room depth.









Again, I'd like to make some improvements, but I don't expect perfection. I'm a bit stuck with my layout. I could really use some improvement in the 100 - 1000 Hz range, especially on the right side. Note I swapped speakers, physically, just to ensure they were "working" and I got the same results, so it's the layout and the room. I know there are 100 things I could fix, but if I can get this region figured out I truly think I'll be happy as I truly believe it's the range that I've always thought was "off".

If I haven't lost anyone yet, I'd love some ideas. That spreadsheet (Barefoot) seems to imply that some OC703 or mineral wool type panels would do a ton for me, at my front wall, even at just 2 or 4 inches. I have no idea if that's the whole wall, or if say a 4' x 4' panel would help get that initial SBIR bounce. I haven't consulted any of the panel companies yet, I thought I'd start here before I got them to spend time.


----------



## nathan_h

Duc Vu said:


> It should. But I just don't see that effectiveness shown in the frequency response. Seems like there are too many other factors at play here.


That’s why we use the models and math to predict what is most likely to make the desired impact….and then we measure and adjust from there if needed.

Someone smarter than me could likely conjecture why those measurements are showing what they do with various amounts of treatment. All I can say is that the results appear to make sense from a RT60 sense and are what I would consider good.


----------



## nathan_h

*grelvis* said:


> Greetings! I've been reading through this thread and will continue to do so. I'd also like to ask for some opinions. I've been living over in the REW thread for a while, learning to use that program and doing what I can as far as tweaking speaker placement and things like that. Unfortunately at the moment (never say never), laying the room out differently isn't an option. I'm a bit stuck with what I have.
> 
> I think I could supply anything anyone would like to see. I've learned a ton regarding the effects of speaker placement and such and what I've found is, basically, for everything I fix I just create a new issue. I've simply got a strange space to contend with. I've also evaluated my nulls and peaks vs. the calculators. For one of them (tripp) very little jives with my reality, aside from the effects of the ceiling. Another, a spreadsheet, (Barefoot) seems to pretty much nail it. I do have a strange room shape to live with. I've analyzed the major reflections and their effect but I think I see that most of them affect a range around 1k and above, and underneath that appears to be determined more by the room shape itself.
> 
> So, after a lot of investigation, I fully realize I have a big mess. I'd like to make some improvements, but I don't expect perfection. It's 95% home theater use so no worries about music quality. I don't have much if any wiggle room for layout, so it's probably diffusers or absorbers to lend some assistance here? I'm hoping so, and not too many if possible.
> 
> I have a Yamaha TSR-700 Receiver with a rather useless YPAO and limited frequencies I can EQ (63, 160, 400, 1k, 2.5k...). I have some very old (25 years?) Boston Acoustics 3-way towers (T830's), I've replaced the surrounds a while back and they actually seem to be performing well - I tried some measurements of the various drivers and before the reflections come in they are reasonably linear and I think still sound good. I don't think new speakers would help me much. Subwoofer is an SVS PB-1000.
> 
> Here's an idea of the room layout
> View attachment 3382829
> 
> 
> Full Range SPL Measurements With Sub OFF
> View attachment 3382830
> 
> 
> And Sub ON (Note that phase change of sub helps tame the 100Hz peaks above)
> View attachment 3382831
> 
> 
> Waterfall of Left Speaker, No Sub (Right is similar, I can supply if needed)
> View attachment 3382832
> 
> 
> And with Sub
> View attachment 3382833
> 
> 
> Impulse Plot of Left Speaker (nothing worth noting later than this, but I can certainly supply if helpful, also Right speaker is similar). For this, I've determined that the 1st 3 spikes are due to 1) Rear wall behind couch, 2) Ceiling, 3) It's a combo ceiling then rear wall). The next around 18ms I couldn't pinpoint but it corresponds to a distance that's almost exactly double the room depth. Mid 30ms's is 4x the room depth.
> View attachment 3382835
> 
> 
> Again, I'd like to make some improvements, but I don't expect perfection. I'm a bit stuck with my layout. I could really use some improvement in the 100 - 1000 Hz range, especially on the right side. Note I swapped speakers, physically, just to ensure they were "working" and I got the same results, so it's the layout and the room. I know there are 100 things I could fix, but if I can get this region figured out I truly think I'll be happy as I truly believe it's the range that I've always thought was "off".
> 
> If I haven't lost anyone yet, I'd love some ideas. That spreadsheet (Barefoot) seems to imply that some OC703 or mineral wool type panels would do a ton for me, at my front wall, even at just 2 or 4 inches. I have no idea if that's the whole wall, or if say a 4' x 4' panel would help get that initial SBIR bounce. I haven't consulted any of the panel companies yet, I thought I'd start here before I got them to spend time.


In that room I would start with three 2x4 foot panels of at least four inches of depth, six inches much better, where the green line is, behind the couch….be sure to have panels coverings from should height to above head height.

Then I would put some on the front wall 3 or 4 of similar size. Using one behind each speaker is fine 

Then depending on how the room sounds and measured at that point I would consider two panels for the ceiling between the tv and seats.

If you want to try to deal with bass modes then a second identical sub that is set up well with something like a mini dsp would be useful.

I might use YPAO or the parametric QE to dial down the 700hz peak you are seeing.


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## *grelvis*

Thanks for the reply. So, suggesting basically lots of panels, rear wall, front wall, ceiling. I figured as much. Any experience to say where to start first? I could easily do behind the speakers, probably do behind the couch, and not likely do the ceiling but it's possible (WAF).

I'm fairly OK with the sub response, and can keep tweaking on that one. My receiver doesn't have the right pre-amp inputs (AFAIK) for a mini DSP. The YPAO was fairly useless per the REW measurements but I could consider it again. EQ frequency options jump from 400 to 1k, and lowering each does get that peak in the middle of them but also nukes those frequencies too of course, which I don't want.


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## nathan_h

*grelvis* said:


> Thanks for the reply. So, suggesting basically lots of panels, rear wall, front wall, ceiling. I figured as much. Any experience to say where to start first? I could easily do behind the speakers, probably do behind the couch, and not likely do the ceiling but it's possible (WAF).
> 
> I'm fairly OK with the sub response, and can keep tweaking on that one. My receiver doesn't have the right pre-amp inputs (AFAIK) for a mini DSP. The YPAO was fairly useless per the REW measurements but I could consider it again. EQ frequency options jump from 400 to 1k, and lowering each does get that peak in the middle of them but also nukes those frequencies too of course, which I don't want.


Here then is what I would do:

Most useful is some thick panels behind your head on the couch. Three of the 2x4' panels that are at least 4" thick. Six inch thick panels would be better.

Then, if you can tolerate more, putting some on the front wall, behind the speakers is great but not strictly required. But that is second, after the wall behind your head.

Ceiling is optional. Something to consider in the future but not nearly as important as the wall behind your head.

----

Mini DSP would go between the SUBWOOFER OUTPUT on the AVR, and the input on the subwoofer.

Its just something to consider if you want to do the best you can with the sub you have. I fear that your version of YPAO may not do anything for the subwoofer response, if I recall correctly.

Regarding YPAO in general: Don't bother with the individual manual options. They don't offer enough choice to make it worthwhile without a lot of finessing. BUT you could try running the automated YPAO system with the Yamaha microphone. That MIGHT do some nice things AFTER you have put up the panels. It is worth a try.


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## Duc Vu

Finally put the panels up on the ceiling. In case you're wondering what the boxes near the panels are, they contain the in-ceiling atmos speakers. I bought them before the drop ceiling was removed, so now I had to make boxes to hang them down from the ceiling. Quite a weird sight.



















Anyway, the panels on the ceiling seem to bring some arguably positive changes to upper low frequencies, as @nathan_h predicted. The RT60 decay is lowered across a broad range of frequencies all the way down to 100Hz - so now what I have is actually a pretty flat line below 400ms, indicating a very controlled listening environment. However, again, not many changes in the frequency response as well as below-100Hz subwoofer-territory frequencies, as expected. Measurement file is attached below.

Next step is running Audyssey. And then, maybe, a 2nd sub. But I honestly don't feel spending more money or time on this. I want to start using the system instead of measuring it 🤪


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## *grelvis*

Duc Vu said:


> But I honestly don't feel spending more money or time on this. I want to start using the system instead of measuring it


I know this feeling!


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## nathan_h

Duc Vu said:


> Finally put the panels up on the ceiling. In case you're wondering what the boxes near the panels are, they contain the in-ceiling atmos speakers. I bought them before the drop ceiling was removed, so now I had to make boxes to hang them down from the ceiling. Quite a weird sight.
> 
> View attachment 3383631
> 
> 
> View attachment 3383632
> 
> 
> Anyway, the panels on the ceiling seem to bring some arguably positive changes to upper low frequencies, as @nathan_h predicted. The RT60 decay is lowered across a broad range of frequencies all the way down to 100Hz - so now what I have is actually a pretty flat line below 400ms, indicating a very controlled listening environment. However, again, not many changes in the frequency response as well as below-100Hz subwoofer-territory frequencies, as expected. Measurement file is attached below.
> 
> Next step is running Audyssey. And then, maybe, a 2nd sub. But I honestly don't feel spending more money or time on this. I want to start using the system instead of measuring it 🤪


I don’t blame you. I would run Audyssey and live with it for at least a few months before considering whether to fiddle more. I think you have done a great job.


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## sukumar

Did anyone use or explored the db3 max insulation product for acoustics? I called the company and they said it absorbs sound very well including low frequency. Here is the link that I am talking about. If I want to test myself, is there any way? Appreciate it.













https://trimaco.com/cms/wp-content/uploads/2020/07/db3-MAX-data-sheet_0720_email.pdf


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## *grelvis*

nathan_h said:


> Here then is what I would do:
> 
> Most useful is some thick panels behind your head on the couch. Three of the 2x4' panels that are at least 4" thick. Six inch thick panels would be better.
> 
> Then, if you can tolerate more, putting some on the front wall, behind the speakers is great but not strictly required. But that is second, after the wall behind your head.
> 
> Ceiling is optional. Something to consider in the future but not nearly as important as the wall behind your head.


Bought a package of Owens Corning mineral wool, grabbed some gloves, spread out some old sheets we use when we paint, and did a little work.

I don't have the plots handy, but I'll say that:

1) Batts surrounding the speakers, even doubled up and placed on each side, was a measureable difference but didn't really fix much. For me, this would not be worth it.

2) Batts behind the couch, in fact simply sitting on the back of the couch, made a huge difference. I've still got some wonky stuff going on but it tamed it dramatically. And the center channel is, I think, impressively flat with just a panel resting on the back of the couch (the MLP and mic are middle of the couch with head just above the cushions).

So, it was worth asking here and worth a small test. Next I'll decide between DIY and a purchase. But it looks like even just a 4" panel behind the couch makes a world of difference. WAF won't be tough if I promise her I'm done after that. I may even get her interested in helping choose a color or going with one that has a picture.


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## nathan_h

*grelvis* said:


> Bought a package of Owens Corning mineral wool, grabbed some gloves, spread out some old sheets we use when we paint, and did a little work.
> 
> I don't have the plots handy, but I'll say that:
> 
> 1) Batts surrounding the speakers, even doubled up and placed on each side, was a measureable difference but didn't really fix much. For me, this would not be worth it.
> 
> 2) Batts behind the couch, in fact simply sitting on the back of the couch, made a huge difference. I've still got some wonky stuff going on but it tamed it dramatically. And the center channel is, I think, impressively flat with just a panel resting on the back of the couch (the MLP and mic are middle of the couch with head just above the cushions).
> 
> So, it was worth asking here and worth a small test. Next I'll decide between DIY and a purchase. But it looks like even just a 4" panel behind the couch makes a world of difference. WAF won't be tough if I promise her I'm done after that. I may even get her interested in helping choose a color or going with one that has a picture.


Cool. Thanks for sharing your results. Yep, killing the reflections off a wall behind your head is often transformative. Glad it helped.


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## nathan_h

sukumar said:


> Did anyone use or explored the db3 max insulation product for acoustics? I called the company and they said it absorbs sound very well including low frequency. Here is the link that I am talking about. If I want to test myself, is there any way? Appreciate it.
> 
> View attachment 3385360
> 
> 
> 
> 
> https://trimaco.com/cms/wp-content/uploads/2020/07/db3-MAX-data-sheet_0720_email.pdf


Could be useful for some situations.

See if they will share the details of their "Test # RAL TL 17-453". Seeing what lab did the testing and by what methodology would be useful.

But in general if one takes their figures at face value (labs can vary quite a bit unfortunately so there could be a five to ten STC difference for the same materials tested in two different labs) then it would appear to be similar to a single layer of drywall with clips/channels.

In other words, their own measurements put it near the bottom of the list of effective sound isolation approaches, so it better be cheap and one's goals for the room should be modest.












_EDIT: I forgot that we are in the room treatment thread, NOT the "soundproofing" thread. This whole post is about whether that DBX stuff is good for "soundproofing" (and the answer is: a little, though it is at the bottom of the list of effectiveness, even if we trust the manufacturer 100%).

However, this thread (and now I think your question) is whether this DBX stuff can be used for in room treatment (sound absorption) to control reflections and so on....and the answer is NO. That is not what it is for. _


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## sukumar

nathan_h said:


> Could be useful for some situations.
> 
> See if they will share the details of their "Test # RAL TL 17-453". Seeing what lab did the testing and by what methodology would be useful.
> 
> But in general if one takes their figures at face value (labs can vary quite a bit unfortunately so there could be a five to ten STC difference for the same materials tested in two different labs) then it would appear to be similar to a single layer of drywall with clips/channels.
> 
> In other words, their own measurements put it near the bottom of the list of effective sound isolation approaches, so it better be cheap and one's goals for the room should be modest.
> 
> View attachment 3385386


Thanks for taking time to reply. STC for dbmax is given 56. I am assuming higher the number, it is good. it is close to all these given in above graph right (57, 58)? Curious to know STC for OC fiber glass as it is viewed as top acoustic material.

Trying to find safe eco friendly material. Unfortunately, denim insulation is not avilable. Will look for alternatives as well. I am still not familiar with the numbers and will try to understand to take bttter decision.


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## sukumar

This cotton material seems very good for acoustic. I wonder if I can use it wherever I wanted and it seems absorption close to 2 inch OC fiber glass with just draperies alone.


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## *grelvis*

nathan_h said:


> Cool. Thanks for sharing your results. Yep, killing the reflections off a wall behind your head is often transformative. Glad it helped.


Of course, after thinking about it some more, I wonder what it'd have looked like if I pulled the couch out and stuck ALL the panels back there  Sigh, just when you think you've exited REW and put away the mic, there's another idea to try. I'll grab a few screenshots to show some of the effects.


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## *grelvis*

Grabbed a few images to share, Hopefully others find them interesting.

First image below is the center channel. Green is my room as-is (front - rear wall separation only about 12', and the couch is bumped up to the rear wall with the mic in the MLP). Blue is the addition of a single 3.5" thick batt of mineral wool insulation resting on the back of the couch (with a sheet underneath that is normally a drop cloth). You can see the overall reduction on the upper frequencies, that some peaks and nulls haven't moved, and that some have clearly shifted.










Next image is similar but for my left speaker. In this case it's not a before / after the batt on the wall, sorry, but it is showing the difference between 1 batt shown in orange and 4 batts (2 deep and 2 high) shown in green. It would seem the additional batts aren't doing a lot, but then again they are concentrated in a single location. Still I hoped that 7" would have had a little more effect on the lower frequencies. Then again, maybe there wasn't a ton to fix there to begin with and the wrong approach, or I just needed a whole lot more.









One more, this one showing the single batt behind the couch in orange, and almost all of the remaining batts surrounding the speaker itself (3 on each side, pressed up to the speaker itself) in pink. Some peaks raised and some nulls lowered. I'd actually say this made things worse.










FYI, yes, it's a wonky room and I have issues! I'm trying to tackle a few things at once, especially that area around 100Hz. Luckily I primarily use it for home theater, not music, and my center channel which does most of the work is pretty decent. When I listen to music I am pretty familiar with, it's sort of awful, and you might tell that by the plots.


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## nathan_h

sukumar said:


> Thanks for taking time to reply. STC for dbmax is given 56. I am assuming higher the number, it is good. it is close to all these given in above graph right (57, 58)? Curious to know STC for OC fiber glass as it is viewed as top acoustic material.
> 
> Trying to find safe eco friendly material. Unfortunately, denim insulation is not avilable. Will look for alternatives as well. I am still not familiar with the numbers and will try to understand to take bttter decision.


Well, the dbmax is NOT for treatment INSIDE a room to tame room reflections. (That is the topic of this thread, and I apologize. I was approaching it for its intended use: Acoustic isolation OF the room.)

Insulation is for treatment INSIDE the room to tame echoes (and somewhat to help with frequency response in some cases).

People do put fiberglass inside walls and it does help with transmission a little but that's NOT the subject of this thread.



*grelvis* said:


> Of course, after thinking about it some more, I wonder what it'd have looked like if I pulled the couch out and stuck ALL the panels back there  Sigh, just when you think you've exited REW and put away the mic, there's another idea to try. I'll grab a few screenshots to show some of the effects.


Don't worry too much. Your graphs look normal. I bet they look even better once you run room correction.

And yes, if you want to completely "go there" then putting six inch thick panels that basically cover the whole wall behind the couch from couch back to close to the ceiling is a useful approach.....especialy in this room where there aren't going to be a lot of other places for panels.


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## sukumar

nathan_h said:


> Well, the dbmax is NOT for treatment INSIDE a room to tame room reflections. (That is the topic of this thread, and I apologize. I was approaching it for its intended use: Acoustic isolation OF the room.)
> 
> Insulation is for treatment INSIDE the room to tame echoes (and somewhat to help with frequency response in some cases).
> 
> People do put fiberglass inside walls and it does help with transmission a little but that's NOT the subject of this thread.
> 
> 
> 
> Don't worry too much. Your graphs look normal. I bet they look even better once you run room correction.
> 
> And yes, if you want to completely "go there" then putting six inch thick panels that basically cover the whole wall behind the couch from couch back to close to the ceiling is a useful approach.....especialy in this room where there aren't going to be a lot of other places for panels.


Thanks for the clarification. My understanding from your reply is I should not consider dbmax for acoustic treatment. I will try to find alternatives.


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## *grelvis*

nathan_h said:


> Don't worry too much. Your graphs look normal. I bet they look even better once you run room correction.
> 
> And yes, if you want to completely "go there" then putting six inch thick panels that basically cover the whole wall behind the couch from couch back to close to the ceiling is a useful approach.....especialy in this room where there aren't going to be a lot of other places for panels.


I have a Yamaha TSR-700 receiver that has YPAO, and I'm not sure it does much. It did a good job figuring out the speaker distances and delays, I'll give it that. But as far as EQ I'm not sure it actually did anything. The manual EQ has limited options (63Hz, then 160, 400, 1k, 2.5k, and then I think 6.3 and 16k). I would suppose YPAO can only adjust those and I'm not sure it can do it better than I can with REW running. I think I'm stopping short of replacing the receiver with something with better correction abilities and just living with the fact the room is what it is. Luckily for me, though I can tell music sounds bad, movies actually sound quite alright. Ignorance is bliss in a way.

I may end up trying all the panels behind the couch, we'll see. I had in mind the couch was the ultimate absorber but... it probably actually isn't. Panels behind the whole thing might make a difference after all.

Still surprised so many at the speakers did so little. The various spreadsheets to calculate SBIR never seemed to match reality either. Probably due to the L shape of the room as opposed to a normal rectangle.


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## nathan_h

*grelvis* said:


> I have a Yamaha TSR-700 receiver that has YPAO, and I'm not sure it does much. It did a good job figuring out the speaker distances and delays, I'll give it that. But as far as EQ I'm not sure it actually did anything. The manual EQ has limited options (63Hz, then 160, 400, 1k, 2.5k, and then I think 6.3 and 16k). I would suppose YPAO can only adjust those and I'm not sure it can do it better than I can with REW running. I think I'm stopping short of replacing the receiver with something with better correction abilities and just living with the fact the room is what it is. Luckily for me, though I can tell music sounds bad, movies actually sound quite alright. Ignorance is bliss in a way.
> 
> I may end up trying all the panels behind the couch, we'll see. I had in mind the couch was the ultimate absorber but... it probably actually isn't. Panels behind the whole thing might make a difference after all.
> 
> Still surprised so many at the speakers did so little. The various spreadsheets to calculate SBIR never seemed to match reality either. Probably due to the L shape of the room as opposed to a normal rectangle.


Note that the version of ypao in that receiver is quite good.

It is NOT limited to those frequencies. You are limited to those frequencies when manually adjusting EQ. 

But ypao on your unit can adjust any frequency it wants. 

The version of ypao you have is VERY SIMILAR to the best version of Audyssey and is very effective. I highly encourage you to use it, after you have placed those panels behind your head.


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## *grelvis*

nathan_h said:


> Note that the version of ypao in that receiver is quite good.
> 
> It is NOT limited to those frequencies. You are limited to those frequencies when manually adjusting EQ.
> 
> But ypao on your unit can adjust any frequency it wants.
> 
> The version of ypao you have is VERY SIMILAR to the best version of Audyssey and is very effective. I highly encourage you to use it, after you have placed those panels behind your head.


Well, OK! I'm sold. Last I tried it I wasn't impressed, it seems like it didn't do anything. Then again I had very little REW experience and there's also a chance that not much can be done! LOL.

I may take pictures of the current settings across the board, and then let it do its thing again (after I add a panel). If nothing else I can at least compare YPAO flat, front, and natural vs. my own EQ work again and be certain about using it or not.

Need to get to work on getting a panel behind the couch. I also want to try again looking at the peaks and dips I have and see if anything can be done short of covering the whole basement with panels or a complete rearrangement of everything. Tame those 100Hz and 300Hz areas, maybe bring up around 200Hz a bit. Try to ID which dimension(s) out of them all might be causing it...


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## nathan_h

Treating 100 hz with treatment is......very hard. You would need to have some corner bass traps that are perhaps 12" thick or more, and even then, it wouldn't do as much as you might want.

On the other hand, room EQ (YPAO in your case) can tame those peaks relatively well.

Note, however, that a good room EQ system will typically have the 20hz region about 10db higher than the 20khz region. This is a very normal room curve or response profile. So YPAO probably won't flatten it completely (and you likely wouldn't like it if it did).


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